[Sciences/BBB/Drug Delivery] Red blood cell-hitchhiking boosts delivery of nanocarriers to chosen organs by orders of magnitude (Brenner et al., Nat Comm 2018)

I know, I know I have been fairly quiet. I have to tell that between attending a scientific meeting, teaching a summer course, taking care of two grants proposals and finally handling three manuscripts. However, sometimes I also like to share some papers published in the field that are interesting or bringing novel ideas or concepts. This one has been suggested by one of the author and this is his quick summary:
We bind nanoparticles to the surface of red blood cells. These nanoparticles are going to be released from the red cells once they pass the first capillary bed. Therefore we can concentrate the nanoparticles in the target tissue. In addition, these nanoparticles potentially can carry one or multiple selected drug(s). So if we inject intravenously the particles are going to be release in the lungs but if we inject through the brain arteries the nanoparticles will be release into the brain vasculature.
It is a very nice of work here published in Nature Communication (I consider this is one of the top OA journal to get published in) and you can download the full-text here.
You can also appreciate this paper likely went into at least one round of review, with a time period of about 7 months between it got accepted for review and accepted for publications.

In this paper, the authors have been working on trying to develop alternative drug delivery carrier, in that case use red blood cells as “piggyback” cells to enhance drug delivery. They tried different formulations on isolated RBCs and identified some suitable for carrying antibodies or proteins.  They called these piggybacking RBCs as RBC-Hitchiking (RH) (I wonder if it is some Easter egg towards the “Hitchiking Guide to Galaxy”).

Upon identification of the right nanoparticle materials, the authors investigated the distribution and the delivery of the conjugates in different organs, as liver and lungs. What is interesting is the amount of injected dose recovered is much higher in the RH than the free-circulating one, in particular in lungs, whether they are bare-naked or bound with a protein. These nano-carriers can be delivered to endothelial cells.

But the interesting snack-bite from this paper is the intra-arterial injection in the carotid artery, in which there was a significant increase in nano carriers delivery in the brain.  Nano-carriers alone show a %ID lesser than 1% (that is about what you expect from delivering antibodies from an IV route towards the brain)  to over 10%.   The delivery was also maintaining the ipsilateral injection site, which is good considering you are likely to treat one brain hemisphere.

Now, time for me to be picky and kind of wish we had information on the PK profile, especially if this approach increased the stability of the nanocarriers. It would be also interesting to see how this technique fare in a experimental disease model (for instance a xenograft brain tumor and see if you can deliver targeted chemotherapy in mice).

Nevertheless it is a good paper that take us out from the classical nanoparticles formulation and try here an innovative and novel approach in drug delivery.

 

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[Sciences/Junk Sciences/Vaccines] HPV vaccine safety – a tale of two studies

“It was the best of times, it was the worst of times” Charles Dickens – A Tale Of Two Cities

If you are following a bit the current news about immunization and vaccines, you likely heard about two studies in regards of the effect of HPV vaccines on population safety, in particular in terms of risk of developing complications or chronic conditions.
Interestingly two studies (to be honest one study and one comment) weighing the pros and cons of HPV public immunization were published within weeks.
One of them was claiming that HPV vaccines increased the risk of cervical cancer in the Swedish population, the other the incidence of autoimmune diseases in the Canadian population, in particular in the population of Ontario province.
One of them was published in a society journal with an reasonably impact factor (IF~8 and Scimago score of 1.7), the other in a journal with inexistent impact factor (Scimago score of 0.2) showing behavior similar to “predatory journals”.
One of them was published “in a peer-reviewed general medical journal that publishes original clinical research, commentaries, analyses, and reviews of clinical topics, health news, clinical practice updates and thought-provoking editorials.”; the other “is a multi-disciplinary academic journal providing a platform for publication of original material and discussion on all aspects of healthcare ethics and the humanities, relevant to and/or from the perspective of India and other developing countries.
One of them was a full-length study with several authors, the other one a rapid communication labelled as “comment” and purposely falsified the author’s name and affiliation (hiding behind an outlook email address), claiming the fear of retaliation by the opposing group.
One of them was a controlled population study, investigating two groups (vaccinated versus unvaccinated) with a sample size of 100’000+ each; the other one tossed epidemiological data together without further stratification and cherry-picked the information.
One of them was concluding the safety of HPV vaccine and absence of increased risk of autoimmunity, the other questioned the safety of HPV vaccine straight from the abstract as “I discuss the possibility that HPV vaccination could play a role in the increase in the incidence of cervical cancer by causing instead of preventing cervical cancer disease in women previously exposed to HPV. A time relationship exists between the start of vaccination and the increase in the incidence of cervical cancer. The HPV vaccines were approved in 2006 and 2007, respectively and most young girls started to be vaccinated during 2012–2013.
After a media firestorm and the strange support of the editorial board towards the author (and still consider the data as legitimate), it got finally retracted. The corresponding author has also been informed he will have four other retractions upcoming.
Guess which one was the flawed study published with a falsified author information and in a journal with a scope outside the content of the article published?
You can these publications here and here.

[BBB/Autism/Junk Sciences] Autism, bleach and the blood-brain barrier: how the CD/MMS cult is promoting child abuse on bogus scientific claims.

I have been blogging about quack medicine, charlatanisms and debunking claims about the blood-brain barrier for few years now. But nothing reach the level of indignation and anger than the treatment reserved for children diagnosed as “on the spectrum” (for autism spectrum disorder or ASD), especially those treated with the “CD/MMS protocol” aka “the bleach protocol”, as recently discussed in various blogs and in news outlet here and there.

Introduction:

“Autism spectrum disorders” that is an umbrella medical definition that is defining children presenting deficiencies in social skills, a particular focus on patterns or objects including certain rituals or organization (e.g. sorting toys by their colors, lining cars in a perfect order, bed linen to be perfectly folded), hyper-sensibility to environmental cues (sounds, light, colors….) and in some cases neurodevelopment or communication delays. Not all autistic children are equals, with very different types of syndromes or conditions (e.g. Asperger’s Syndrome, Rett’s Syndrome……).

Although the etiology of ASD is deeply anchored into genetics as a major risk factor (followed by neuroinflamamation during gestation due to infectious diseases), the diagnostic still remains flexible and have been standardized only recently through the “Diagnostic and Statistical Manual for Mental Disorders”, currently in the fifth edition. Such standardization is as recent that a notable number of adults often get diagnosed “on the spectrum” late in their life, often during their adulthood.

Until now, there is no therapies to address such condition and mostly involves medication for treating other conditions associated with the disease (epilepsy is often diagnosed in children on the spectrum) or behavioral therapy (also known as applied behavioral analysis).

Because the diagnosis of autism is perceived and feared amongst parents and the lack of therapies are obvious, such environment creates a fertile ground for charlatans and snake oil seller preying on fear to make profit, selling parents a “cure-it all” potion or interventions, using these children as “guinea-pigs” by pushing protocols or treatment that are best have poorly fared in the scientific literature (most of the time published in low-impact factor journals) if not completely bogus.

A few example of such doubtful or quack remedies are dietary restrictions (gluten-free/casein-free diets), injection of biologics (GcMAF), if not dangerous interventions such as the use of hyperbaric oxygen treatment or use of chelation therapy. But amongst them reside one of the worst treatment: the CD/MMS protocol, or as we should call it the “bleach protocol”.

The CD/MMS protocol: a fancy name for a bleach protocol targeting autistic children

CD stands for chlorine dioxide (O=Cl=O) a bleaching agent used mostly for industrial purposes. CD shares similarities with the household bleach (O=Cl-) and both as referred as chlorinated bleaching agents.

Until recently, Kerri Rivera has been actively promoting the CD/MMS protocol as a “cure for autism” through her book co-authored with other charlatans named “Healing The Symptoms Known As Autism”. in this book, they promote the use of CD via ingestion of droplets or via enema administration. Such aggressive chemical is enough to damage the mucosal layer lining the luminal wall of the gastrointestinal (GI) tract and its detachment. Such detached mucosal layer is often labelled as “parasites” which indeed any respected parasitologist will quickly debunk such fallacious claims.  Kerri Rivera promotes the use of this protocol to cure “autistic children” and up until recently was promoting such treatment in the Autism One conference. She discussed in details about this protocol on the Chapter 8 of her book and makes disturbing claims about the blood-brain barrier.

Fallacious things Kerri Rivera said about the blood-brain barrier in her book:

The first fallacious claim from Kerri Rivera appears on Chapter 3, pages 48 and 49. In this chapter, she promotes the gluten-free/casein-free/soy-free diet as a treatment for autism with the excuse of the “leaky gut syndrome” as the following: “This results in poor digestion, which facilitates the entry of these harmful proteins [gluten and casein] directly into the bloodstream, where they can cross the blood-brain barrier.“. I never heard about gluten and casein crossing the BBB, especially considering that these are large peptides and therefore have to use transporters and receptors. Of course, her claims is not backed by a reference to a study.
Then she refers to this ” Improperly digested gluten and casein fragments can both enter the bloodstream and cross the blood-brain barrier. Because of their opioid properties, these peptides can react with opiate receptors in the brain to cause effects similar to those of an opiate drug such as heroin or morphine.7 These opiates are called gluteomorphin (or gliadorphin) and casomorphin, and can react with some parts of the brain, for example, the temporal lobes, which are actively involved in the process of the integration of language and hearing. Interestingly, these are two of the areas most affected by autism.

She cites this page for her claims. Interestingly, if you look at the page this claim is based on making a parallel between celiac disease and a speculation and hypothesis as cited: “Now in terms of autism, the situation is somewhat different because children with autism generally do not have celiac disease and do not have the DQ2 genotype problem. Whereas the problem of celiac disease is well proven in scientific studies, the problem with gluten sensitivity in autism is less well studied. The autism hypothesis involves, like celiac disease, the toxic effects of small peptides, generally in the range of five to seven amino acids in length (termed casomorphin and gliadorphin, as noted below). It is believed that these peptides from gluten, as well as certain peptides from cow milk protein (casein), can somehow cross the intestinal microvillus barrier and reach the blood stream.”

In a previous edition, Rivera went further and cited two papers to back her claims (now this claims has been watered down and put in the FAQ section of this chapter):  a study from Reichelt1 and colleagues and a  review from Shattock and colleagues2. Firstly, the citation of Shattock review is outdated and only provide an exhaustive overview of published studies supporting or dismissing the theory of opioid-excess. It has no scientific value as it does not provide a direct evidence of such claim. More troublesome is the following study led by Hunter and colleagues published by Hunter and colleagues in 2003 investigating the presence of opioids mimetics in patients urine and published in Developmental Medicine & Child Neurology3, a journal with an acceptable impact factor (IF=3.29). Using liquid chromatography coupled with mass-spectrometry (a common analytical technique used for measuring metabolites in biological fluids), the authors have investigated the presence of opioids in a cohort of 10 children with ASD and used siblings as controls. Interestingly, the authors failed to notice notable differences (as defined by presence of unique peaks) in the urine chromatogram of ASD children compared to controls. The authors further investigated the presence of opoid peptides previously cited by Shattock, in particular beta-casomorphin (a peptide byproduct obtained from casein degradation) and alpha-gliadin (a peptide byproduct obtained from gluten degradation). The authors failed to identify the presence of both peptides, based on retention time compared to standard or based on the m/z index.  This publication irated enough Shattock to be followed  by a comment to Editor and a scientific joust between Shattock and Hunter4, however an  editorial published by John F Mantovani resumes well the context in which the initial statement of Shattock was published5. At this time, ASD etiology was completely unknown and remained highly speculative. The publication (and subsequent retraction) of the so-called “Wakefied study” 6 linking MMR vaccines to ASD cases, but also documenting the presence of inflammatory bowel disorder in ASD patients, such condition is known to triggered by gluten and casein in patients suffering from celiac diseases. As Mantovani mentioned, the adoption of the theory of gluten and casein was correlating with the same approach than the vaccine without any scientific rationale. The study from Hunter indeed showed the lack of evidence about the claim made by Shattock. The amount of studies linking autism and exorphin remains very low. A query on Pubmed (the database of the National Library of Medicine) using the keywords “autism” and “exorphin” results in only 7 publications with 3 publications from Reichelt, KL and two publications from Brudnak, MA.
This brings the concern of data reproducibility. In order to have a scientific claim that have strong significancy you need two factors: a significant number of publications that investigated such statement and the publications of findings from different research groups. Having the monopoly of such investigation solely on a single research laboratory raises the issue of data reproducibility and reliability.
In this case, the study of Reichelt is very interesting, as its publication quality appears dubious at different levels. The journal of Microbial Ecology and Health Disease has recently adopted the “open-access” policy. Prior its publication as open-access, the journal has an 2013 unofficial impact factor of 0.933. The “open access” and the low IF raise red flags: such journal may be a potential “predatory journal” (a term coined by Retractionwatch.org, a website tracking scientific articles retraction). In this model, the cost of open-access is levied by the payment of hefty publication fees ($3000-5000) usually higher than subscription-based journals. Because of such financial gain, the peer-review process may be altered and even may be completely omitted, removing the quality control accomplished by peer-review. This lack of peer-review process is particularly blatant by the absence of clearly structured “methods” sections, odd wordings for a scientific (“ELISA typed as Elisa, thaw over night, eight-hundred microliters”), the source of samples (Association Planet Autism (Italy), samples from Slovenia, Serbia and Australia) and the overall format of the paper figures with some appearing as a screenshoot of a Powerpoint presentation or from printed copies. It raises some skepticism about why the author (based in Norway) failed to collect samples from Norwegian ASD patients.

In the previous edition, Rivera linked these studies to a “leaky bowel syndrome”. A major flaw in this claim is the absence of citing the original publication for Hsaio and colleagues7 that have demonstrated the presence of a “leaky gut syndrome” in mice showing an ASD phenotype. Instead Rivera cites the Gluten Free Society webpage as a source of information (http://www.glutenfreesociety.org/gluten-free-society-blog/dr-fasano-on-leaky-gut-syndrome-and-gluten-sensitivity/).

Dr. Alessio Fasano is certainly a respected researcher in celiac diseases but as noted with pseudoscience and activists groups lacking the scientific knowledge, cherry-picking and extraordinary extrapolation. In particularly in this case by the Gluten Free Society, those as their Facebook webpage mentions, identify themselves as alternative and holistic health society. This is again a red flag on the mission and purpose of this society that have little or no scientific evidence to support their claims except deviating, cherry-picking and reformulating genuine studies to push for their agenda.

Under normal conditions, the intestinal and the blood-brain barrier (BBB) (Figure 1) provides a tight cell monolayer creating a gut-blood and a blood-brain barriers respectively. Under normal conditions, such barrier is achieved by the presence of tight junctions complexes stopping the diffusion of electrolytes and water between the two compartments. Only digestion byproducts such as amino-acids or glucose are transported through dedicated nutrient transporters or solute carriers, whereas bigger entities such as peptides, proteins and pathogens have virtually no diffusion). Only lipids (fatty acids, cholesterol…) and drugs (designed as lipid-soluble chemicals) can passively diffuse across the barrier by mixing themselves with the phospholipid bilayers making the cell membranes.

Picture1

In the study from Hsiao, the authors demonstrated indeed the presence of a “leaky gut” as measured by an increase in FITC-dextran permeability with an estimated size of 4kDa (that’s about the size of a peptide of 36 amino acids). Even is such peptides can cross a “leaky gut”, they still have to cross the BBB. Some scientific studies have demonstrated the biological activity of opioids analogs obtained from digestion byproducts, including gluten and casein. Yet, a review from Lister and colleagues 8 denoted that a majority of these studies were based on intracerebroventricular (ICV) injections (or intracranial). This drug delivery approach allows to bypass the BBB but also is a very invasive approach that is used in clinical settings only for emergency and severe cases.

If such peptides were to cross the BBB and exert the biological activity discussed by Rivera, they have to have a dedicated peptide transporter that can deliver such peptides from the blood to the brain side. The number of peptides capable to cross the BBB has been recently reviewed by Banks 9, a well-established BBB scientist in the transport and delivery of peptides and inflammatory cytokines across the BBB. There is no mention about any of the opioids mentioned by Reichelt or Shattock publications. Furthermore, the increase in gut permeability appears unlikely or indirectly related to gluten or casein-sensitivity, as the authors demonstrated a change in the gut microbioma, in particular changes in Bacteorides fragilis as well as changes in metabolites discovered in serum plasma. However this study has to be taken with a lot of precaution due to the differences related to interspecies variation, the behavioral representation of mice to model ASD and more importantly, similar studies in human patients investigating samples from stools and plasma levels to observe if similar trends or biomarkers are noted in humans.

The next chapter that talks about the BBB is the Chapter 5, in which she discussed about the use of CD/MMS protocol, claiming to hunt their imaginary parasite inside the brain as mentioned by the following: ” In early 2011, we added enemas to the protocol to kill the pathogens causing dysbiosis in the large intestine (we didn’t know about parasites yet). We wanted to get the chlorine dioxide into the blood stream so it could kill the biofilm that exists in the blood. In this way, the blood can carry the CD past the blood-brain barrier to kill pathogens in the brain
When we are detoxing, it is absolutely critical to keep the colon moving and avoid the reabsorption of toxins through the intestinal walls. Enemas allow us to do just this. Some toxins can exit the intestine through the intestinal wall (more so if leaky-gut syndrome is present), and cross the blood-brain barrier, therefore affecting cognition and behavior. When we cleanse the colon, we get those out before they can cross into the brain, and we detoxify the lymphatic system, liver, and gallbladder.
The following argumentation of Rivera is very interesting as she is referring to Dr. Andreas Kalcker and the parasites at the base of her bleaching-based therapy. Let’s first identify Dr. Kalcker. According to his official biography (http://www.andreaskalcker.com/en/biography.html), he studied economics in Barcelona and has earned a Ph.D. in biophysics and alternative health without mentioning his alma matter. This is very puzzling, as any genuine Ph.D. holder will mention the institution that granted his/her degree. Furthermore, the deliverance of a Ph.D. in biological and biomedical sciences (and I believe in any scientific domains) requires the publication of at least one publication in a peer-reviewed journal. Notably, the search of Dr. Kalcker publication in either Pubmed (NLM) or in Sciencedirect (Elsevier) database leads to inconclusive results. At this stage, his Ph.D. degree claim is highly doubtful and raises concern about the credentials of Andreas Kalcker to hold such title.
The main question that can arise is on which expertise Dr. Kalcker discusses about autism, parasites, blood-brain barrier and nutrition? The author of this critique has 11 years of scientific research experience in the blood-brain barrier, 15 peer-reviewed publications.
The gut-brain axis is still a fairly new concept in the BBB field. Up to now, there is only one study that have demonstrated the beneficial effects of gut microbioma on the BBB development during gestation 10 and requires more studies to further confirm this single report. Furthermore, ASD diagnosis and mechanisms of disease have highly progressed since the original retracted publication of Wakefield and colleagues. It is now a consensus that ASD is triggered by two major factors: a genetic and an environmental factor11-14.
The current consensus is the predominance of the genetic factor that set the risk of ASD development and different factors in particular exposure to environmental toxins may trigger the onset of the condition. This second aspect is very interesting, as the penetration of such toxins across the BBB is poorly understood and believed that the presence of efflux drug transporters and phase II metabolism enzymes would void the penetration of such compounds across the BBB and target neurons. Such statement is supported by the ability of the BBB to act as a very strong barrier towards xenobiotic (drugs and toxins), we estimate than less than 5% of current drugs are capable to cross the BBB. The presence of such BBB is a main challenge for drug delivery 15, 16. However, scientific literature yet has to demonstrate how such environmental polluants mar the BBB and how they may affect brain development during gestation that leads to the ASD onset.
Therefore, we can reasonably ask the following question:

  1. On which scientific basis Kelly Rivera supports the claim of parasitic infection? There is no published scientific literature supporting her claim.
  2. Furthermore, under which expertise and scientific literature Dr. Kalcker built his theory on the improper digestion?

According to the Merriam-Webster Dictionary (http://www.merriam-webster.com/dictionary/theory), the definition of theory is “the analysis of a set of facts in their relation to one another”. Neither Kerri Rivera nor Dr. Kalcker have the credential to set a theory because there is no scientific facts to support their theory.

Therefore their tentative to explain their rationale is deeply flawed and should be considered as wrong until a significant number of studies with the adequate scientific quality and neither Rivera or Dr. Kalcker have demonstrated the credentials to exercise a diagnosis or establish a treatment regimen and are legally unlicensed to practice medicine (diagnosis) or pharmacy (treatment) and may face severe legal issues to do so.

The most compelling fact of Rivera and Dr. Kalcker are their active participation in the sell of MMS and CD as a treatment from autism. Such behavior is a clear sign of conflict of interest, a modern form of snake oil sell and a deliberate act of poisoning. Such misuse of public trust and poisoning has lead to the arrest of Dr. Kalcker in Spain in 2014 as reported by the bancdmms website (http://www.bancdmms.com/#!about1/c157n) as well as pro-MMS groups.

In conclusion, until now there is not direct evidence of a gut-brain axis interaction triggering ASD is until now a fallacious statement. There is no clear evidence of such statement, only a series of meticulous cherry picking studies from predatory journals and retracted articles. The direct evidence of gluten and casein peptides in ASD patients is weak and doubtful and would requires a substantial re-evaluation of such claims until other independents research groups demonstrates similar outcomes under controlled conditions.

Furthermore, the etiology of ASD as presented by Rivera and Dr. Kalcker is pure fallacy as none of them have the expertise, credentials and the scientific evidence to make such claims but also have deliberately ignored a sustained and solid publication records concerning the diffusion of peptides across the BBB and the etiology of ASD as a neurological disorder with a high genetic background (supplemented by an environmental factors).

Because the etiology of ASD at this time remains elusive, the treatment of ASD by medication remains until now undocumented, even using pre-clinical models. Only an early diagnosis and intervention by behavioral therapy have been proven successful to improve behavioral and social outcome in ASD patients.

Using common tactics of pseudoscience to distract a non-scientific literate audience, Rivera shows her ability to build an argument on fallacious statements with a an obvious conflict of interest (the endpoint is to sell her MMS/CD cure), as well as a documented harmful outcome of such treatment.

References:

  1. Reichelt KL, Tveiten D, Knivsberg AM, Bronstad G. Peptides’ role in autism with emphasis on exorphins. Microb Ecol Health Dis 2012; 23.
  2. Shattock P, Whiteley P. Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention. Expert Opin Ther Targets 2002; 6(2): 175-83.
  3. Hunter LC, O’Hare A, Herron WJ, Fisher LA, Jones GE. Opioid peptides and dipeptidyl peptidase in autism. Dev Med Child Neurol 2003; 45(2): 121-8.
  4. Shattock P, Hooper M, Waring R. Opioid peptides and dipeptidyl peptidase in autism. Developmental Medicine & Child Neurology 2004; 46(05).
  5. Mantovani JF. Not knowing. Developmental Medicine & Child Neurology 2003; 45(02).
  6. Wakefield AJ, Murch SH, Anthony A, Linnell J, Casson DM, Malik M et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 1998; 351(9103): 637-41.
  7. Hsiao EY, McBride SW, Hsien S, Sharon G, Hyde ER, McCue T et al. Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders. Cell 2013; 155(7): 1451-63.
  8. Lister J, Fletcher PJ, Nobrega JN, Remington G. Behavioral effects of food-derived opioid-like peptides in rodents: Implications for schizophrenia? Pharmacol Biochem Behav 2015.
  9. Banks WA. Peptides and the blood-brain barrier. Peptides 2015.
  10. Braniste V, Al-Asmakh M, Kowal C, Anuar F, Abbaspour A, Toth M et al. The gut microbiota influences blood-brain barrier permeability in mice. Sci Transl Med 2014; 6(263): 263ra158.
  11. Fakhoury M. Autistic spectrum disorders: A review of clinical features, theories and diagnosis. Int J Dev Neurosci 2015.
  12. Correia C, Oliveira G, Vicente AM. Protein interaction networks reveal novel autism risk genes within GWAS statistical noise. PloS one 2014; 9(11): e112399.
  13. Pinto D, Delaby E, Merico D, Barbosa M, Merikangas A, Klei L et al. Convergence of genes and cellular pathways dysregulated in autism spectrum disorders. American journal of human genetics 2014; 94(5): 677-94.
  14. Rossignol DA, Genuis SJ, Frye RE. Environmental toxicants and autism spectrum disorders: a systematic review. Transl Psychiatry 2014; 4: e360.
  15. Cucullo L, Aumayr B, Rapp E, Janigro D. Drug delivery and in vitro models of the blood-brain barrier. Curr Opin Drug Discov Devel 2005; 8(1): 89-99.
  16. Abbott NJ. Blood-brain barrier structure and function and the challenges for CNS drug delivery. Journal of inherited metabolic disease 2013; 36(3): 437-49.

 

[Sciences/BBB] Why the vitamin K shot in newborn matters

I have seen the topic of vitamin K (VitK) shot coming over and over in various discussion groups, with some parents weighing the need of the VitK in newborns. One of the main argument in favor for the injection of VitK in newborn is its ability to reduce the risk of cerebral bleeding (cerebral hemorrhage).
I thought a post on this topic would provide a great help in understanding the physiological role of VitK, the consequence of brain hemorrhage and conclude on the importance of the VitK shot.

1.What is the vitamin K?

Vitamin K is a fat-soluble vitamin that is mostly obtained by our gut microbiota and accessory from our food intake (in particular leafy greens and liver).

220px-Phylloquinone_structure.svg

During gestation, the fetus obtains it from the mother, as such vitamin passes through the placenta barrier. Vitamin K plays an important role through its biochemical cycle called “the Vitamin K cycle”. Vitamin K can convert glutamyl residues present in proteins into gamma-carboxylglutamyl residues as depicted in the picture below:

F1.large

Such modified glutamyl residues are present in particular set of proteins called “coagulation factors”. These coagulation factors are important pieces of what we refer as the “coagulation cascade”.
400px-coagulation_full-svg

I know this graph is complicated but what we care here is the final part of the cascade. The presence of intrinsic damage or trauma, we have the activation of several coagulation factors. Amongst those that are VitK-dependent, we have factor VII (seven), IX (nine) and X (ten). Prothrombin, upon activation by factor X  is converted into thrombin, which in turn cleaves the soluble fibrinogen into the insoluble fibrin. Fibrin acts as a mesh and forms a fibrin clot that will patch the bleeding area. This is an important physiological response when you rupture a blood vessel. The coagulation cascade will create a clot that will stop the bleeding process, saving you from a risk of loosing too much blood and entering an hypovolemic shock. One organ is particularly sensible to brain bleed, this organ is the brain.

2. Brain hemorrhage: small numbers, big damage

In this section, I will mostly discuss about brain bleeds in regards of hemorrhagic stroke but you can apply the same pathophysiology to brain bleeds induced by brain trauma. Brain bleeds are the second type of stroke. They account for about 15% of total stroke events, but account for 40% of stroke-related deaths.

subarachnoid-800x416

We have different types of brain bleeds. In stroke, we usually have a type of brain bleed called “intracerebral hemorrhage” (ICH) that happens deep inside the brain. There are other types of hemorrhage called “sub-arachnoid hemorrhage”. In that case, the brain bleeds occurs in the sub-arachnoid space, a space between the brain and the skull. This type of bleed results into an ischemic stroke (due to a lack of blood perfusion in blood vessels beyond the bleed site) and a brain swelling (resulting in the crushing of the brain tissue due to increase intracranial pressure).

During the injury heme (from damaged astrocytes, neurons and red blood cells) is released in the extracellular space. Heme is a very strong pro-oxidant molecule resulting in the formation of radical oxygen species (ROS) such as anion superoxide (O2*-) and hydrogen peroxide (H2O2), which in turn further induce oxidative stress and cellular damage.

The major type of cells that suffers of such damage at the greatest extent are neurons. Neurons are highly sensible to such injury and unlike other cell types neurons do not divide anymore (post-mitotic cells). A dead neuron is a dead neuron. There are some studies suggesting a possible regeneration of neurons in certain brain regions in rodents (mice, rats), yet the presence of an evidence pointing out at similar mechanism in humans are yet to be demonstrated. Furthermore, there is still no evidence that stem cells (including cord blood stem cells from umbilical cord) can provide a repair of such brain region following injury.

As of today, a dead neuron is a dead neuron. The ability of a damaged brain region to recover is very limited.

3. Why Vitamin K shots?

As we just have explained here, we know that VitK is essential in coagulation and we also understood the impact of brain bleed on the brain. Thus, reducing such brain bleed can be done in the short-term by the induction of the coagulation cascade.
As we mentioned, babies get their VitK from the placenta, but by the time they are born, they are already coming with a low VitK. We also mentioned that the VitK is primarily produced by the gut microbiota. It will take weeks if not months for babies to get a gut microbiota that is functional enough to produce the VitK (I speculate that such microbiota is not present until the age of 12 months when baby eat a diet similar to adults). We can speculate that food (breast milk or baby formula) should provide a source of VitK but providing a steady and standardized intake from dietary is near impossible to achieve.
Furthermore, there is no lab tests or techniques that can predict the onset of a brain bleed. Furthermore, brain bleed has a very high mortality rate and very high morbidity rate including cerebral palsy and other brain damage.
Therefore, ensuring a source of VitK right at birth is the best approach to ensure the baby has enough VitK to have a functional coagulation cascade. In case of a brain bleed, we can expect to have a rapid response of the body to ensure a emergency clotting process ongoing until the doctors can intervene and stop such bleeding to happen and clean any possible brain bleed.
This is why it is important to opt-in for a VitK shot. Once a brain tissue is damaged, there is no evidence yet that there is regeneration of such area. Neurons do not divide anymore by birth and there is no evidence yet of stem cells (including stem cells from cord blood) able to repair such damage.

 

[Neurosciences/Aluminum] Does the latest paper from Exley show a link between ASD and aluminum?

Someone brought my attention today about the most recent Exley paper out in the press titled “Aluminium in brain tissue in autism” (the title could have been better but well….) and published in the journal “Journal of Trace Elements in Medicine and Biology“.
Let me put this straight, this is not a paper that has evidence of scientific fraud or data manipulation. There is no duplicated images, no suspicious blots. The problem I have with this paper is its deep experimental flaws and data analysis that nonetheless should not have passed through the peer-review filter.

  1. Before we dive into the paper, lets put the paper into context
    Lets just put the paper in the context. It was received on October 26th (Thursday). Came back in its revised form on November 21st on Tuesday and accepted for publication on November 23rd (Thanksgivings for the US, but since the editor-in-chief (EIC) is in Europe no Thanksgiving here). Let that sink it a bit: in a bit more than three weeks, it got send to review, came back from review and got revised in 26 days. In my standard of reviewing for journals and publishing my papers, thats some faster-than-light peer-reviews. I usually wait 4-5 weeks by the time I submit mine and get the editor reply to my submission with the infamous reviewers comments. Does a fast-reviewed manuscript means a bad manuscript? Not necessarily, but it can mean that maybe the peer-reviewed was not optimal, rushed or even worse just botched. Based on the quality of the data presented, I am leaning towards a botched review. Thats quite disappointing because the journal holds a decent impact factor (~3 for 5-year impact factor) and you expect an okay review.
    Then comes another problem. Exley published this paper (as well as few others) in the journal…..in which he holds a seat in the editorial board. Nobody can exclude the possible conflict of interest. Consider that: if you were an EIC, would you provide the same rigor and objective decision on a paper submitted by a colleague sitting in your editorial board than a paper submitted by Doe and colleagues?
    Not forbidden, but if you can avoid it, avoid it. Transparency is key and publishing in diversified journals (unless it is society-official journals) is an indicator of an healthy research.
    Finally, the last thing to keep in mind before I deconstruct the paper is the funding source. According to the acknowledgment section “The research is supported by a grant from the Children’s Medical Safety Research Institute (CMSRI), a not-for-profit research foundation based in Washington DC, USA.”  Behind the fancy name is just another anti-vaccine foundation that will play “the vaccine safety” card to peddle their pseudosciences. So we can claim that Exley is a shill for CMSRI, since he received monetary support for his research. Does that mean the research is completely bogus? No, but it means it will require further scrutiny, especially when the claim of the study goes against the consensus in the field (aluminum in vaccines is safe).
    Same goes if a study funded by Big Tobacco claimed the absence of correlation between lung cancer and smoking or if Big Sugar claimed the absence of correlation between type 2 diabetes mellitus and consumption of sweetened beverages.
  2. So what is wrong with this paper?
    For those who wants to read the paper with me, you can download it here (I assume it is open-access, so you should not have an issue with the paywall). Exley has a publication record on aluminum, especially when it comes to its possible ecotoxicity and the impact of aluminum on certain biological processes.
    The introduction is damn short, half a page of a double-spaced document but set the tone, this study will investigate the relationship between autism and aluminum in the brain.
    Samples are obtained from the Oxford Brain Bank, but felt short to indicate the source of the tissue (like a catalog number) and how this source of materials was complying with the institutional review boards (IRB). Basically, for any research involving human subjects or human tissues, you have to comply with the IRB that such specimens are used for a certain and defined use and foremost been anonymized.
    We have 5 patients that were diagnosed as on the autism spectrum and immediately we can pinpoint an important issue: there are no controls and that’s one of the big and unforgiving flaw of this paper.
    The authors then used two techniques to localize and quantify the Al in different cortical regions (and sometimes hippocampal regions). They have used three technical replicates (random sampling from the same cortical lobe) for measuring the Al content using an atomic absorption spectrometry and used lumogallion (aka4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulphonic acid, a fluorescent dye initially described to localize Al in plant roots). This dye have an excitation/emission spectra close from FITC/Alexa Fluor 488. It has been also used for live cell imaging , in particular to study how macrophages process Al present in vaccines adjuvants (http://www.sciencedirect.com/science/article/pii/S0022175915001222).
    Considering the equipment mentioned in the method, the microscope used provides the right excitation bandwidth filter and provide a long pass emission filter for anything over 510nm.Then things get weird, in the result sections, the authors mention the following:”We examined serial brain sections from 10 individuals (3 females and 7 males) who died with a diagnosis of ASD and recorded the presence of aluminium in these tissues (Table S1).“Where is the number coming from? Why don’t we have the same numbers in the Materials and methods?The other problem is the over interpretation of the data. To be brief, the lumogallion will show some punctuated pictures. The authors show some brightfield pictures overlapping to show the tissue structure but does not really help the reader. A DAPI stain (to stain cell nuclei) as counterstain would have been much more informative, it would helped to distinguish background noise from possible Al inclusion. Again, keep in mind we have no controls. The other issues with immunostaining is the high risk to cherry pick the data. You will be naturally inclined to show the presence of a positive risk but this cannot be used for quantitation. Thus, the use of the second method is welcomed as a complementary technique.
    For those not familiar with fluorescence, there is an important notion to keep in mind when analyzing the data: ensuring you keep the same exposure time, the same brightness or contrast and foremost have a negative control to set your exposure time. You can see a sketch explaining here on one of my fluorescence staining (based on my data, I concluded the expression was weak if not negative).

    Slide2

    The background subtraction is also a bit weird. I acknowledge the assessment of autofluorescence is a good control, but you expect to see a low staining. But foremost, you cannot overlap two distinct slices, as proximal as it can be. For instance, in Figure 1, you see some lumogallion staining and below the fluorescence  from the “control” using the adjacent slice. The lumogallion also seems to have a very high background.
    Picture1
    It seems lipid-rich environment increase dramatically the fluorescence of lumogallion (if you look at the spectra, the dissolution of the dye in Triton-X100 solution (b, a detergent) dramatically increase the excitation and emission spectra compared to water (a)).
    What I found troubling is this sentence in the results section: “We examined serial brain sections from 10 individuals (3 females and 7 males) who died with a diagnosis of ASD and recorded the presence of aluminium in these tissues (Table S1). Excitation of the complex of aluminium and lumogallion emits characteristic orange fluorescence that appears increasingly bright yellow at higher fluorescence intensities. Aluminium, identified as lumogallion-reactive deposits, was recorded in at least one tissue in all 10 individuals. Autofluorescence of immediately adjacent serial sections confirmed“.
    If you are a bit a fluorescence microscopy savvy, you know that the “emission color” we see in the objective is never caught by the CCD camera. These camera have in the most majority a B&W output for the simple reason that they have a much higher sensitivity than color cameras. You can always re-create colors in the micrograph pictures using various “lookup tables” (LUTs) that will give a pseudo color based on the level of grays. This is very useful when you samples different excitation/emission channels (for instance, samples stained with DAPI and two antibodies, one conjugated with Alexa Fluor 488 and the other with Alexa Fluor 546 or further down).
    The problem inherent with fluorescence is you can make thing fluoresce or end up with a false-positive signal if you increase the light beam (usually never happens because it is set) or if you increase the exposure time of your camera (this is the most common issue). As you increase exposure, you increase the risk to capture non-specific signal like autofluorescence signals.
    The other problem here is how to explain this sudden shift from orange to yellow?  This seems more like a subjective observation than something caught on camera.  That can be due to different things. You can have some bleed-through of the dye that is normally emitting in a certain wavelength but if it is strong enough can appears in neighboring emission channels. This thing rarely happens with a good fluorescence microscope that have defined filter cubes that allows the diffusion of certain emission wavelengths (for instance, my microscope have a DAPI, Alexa Fluor 488 and Alexa Fluor 555 cubes that only let the respective emission wavelengths  with 20nm-margin error to cross through the objective and reach the camera and binocular).
    Usually, we have to deal with bleed-through when you use flow cytometry and usually is solved using fluorescent dyes latex beads and by following a protocol called “compensation” (this has the result of removing any noise and keeping only the signals).
    We cannot also exclude that such fluorescence is just an autofluorescence from lipofuscine inclusion bodies. Lipofuscin is a lipid-based compound naturally produced by our cells. It has an important concentration in the central nervous system, however it is normally cleared out by cells. Failure in the clearance of lipofuscin is associated with different diseases called “lipofucsinosis” such as Batten’s disease. Even the author admit the possible presence of lipofuscin inclusions “Intracellular aluminium was identified in likely neurones and glia-like cells and often in the vicinity of or colocalised with lipofuscin (Fig. 5).” Lipofuscin is also capable of autofluorescence, although it is more in the wavelengths matching DAPI. Lipofuscin has an excitation/emission peaks at 360 and 435nm respectively but has been reported to also show fluorescence at 510nm when excited at 488nm (https://www.sciencedirect.com/topics/neuroscience/lipofuscin).
    Compared to the lumogallion excitation/emission spectra (507/567), we cannot exclude the presence of a phenomenon called “FRET” (Fosterman Resonance Energy Transfer) in which the excitation of lipofuscin (as the microscope excitation bandwidth is 470-495nm) provide enough energy to the photons emitted by the lipofucsin to excite nearby lumogallion dyes. Because the microscope setting used in this paper has no restricted bandwidth (it let pass any photons harboring a wavelength of 510nm and more), it may explain this orange-to-yellow transition noted by the author. The presence of a DAPI nuclear stain would greatly helped to identify this region as grey matter (rich in cells) or white matter (rich in lipid-rich myelin sheets). Thus, we can legitimately questions the nature of these as it these punctae labelled as “Al inclusion” are simply lipid inclusion or some artificial noise due to the tissue processing. This is where controls come as critical, it can help you sort the signal from the noise.

     

    The second big issue with this paper is the over-interpretation of what the experimenter see. The experimenter wants to see Al inclusion in monocytes? So be it: “Aluminium-loaded mononuclear white blood cells, probably lymphocytes, were identified in the meninges and possibly in the process of entering brain tissue from the lymphatic system“. Or maybe these are astrocytes, or neurons, or microglial cells, or blood vessels….or whatever the author wants to believe in: “Aluminium could be clearly seen inside cells as either discrete punctate deposits or as bright yellow fluorescence. Aluminium was located in inflammatory cells associated with the vasculature (Fig. 2). In one case what looks like an aluminium-loaded lymphocyte or monocyte was noted within a blood vessel lumen surrounded by red blood cells while another probable lymphocyte showing intense yellow fluorescence was noted in the adventitia (Fig. 2b). Glial cells including microglia-like cells that showed positive aluminium fluorescence were often observed in brain tissue in the vicinity of aluminium-stained extracellular deposits (Figs. 3&4). Discrete deposits of aluminium approximately 1m in diameter were clearly visible in both round and amoeboid glial cell bodies (e.g. Fig. 3b). Intracellular aluminium was identified in likely neurones and glia-like cells and often in the vicinity of or colocalised with lipofuscin (Fig. 5). Aluminium-selective fluorescence microscopy was successful in identifying aluminium in extracellular and intracellular locations in neurones and non-neuronal cells and across all brain tissues studied (Figs.1-5). The method only identifies aluminium as evidenced by large areas of brain tissue without any characteristic aluminium-positive fluorescence (Fig. S1).
    This is the second big mistake of this paper. If the author wants to make the claim he proposed here, then he has the obligation to show a counterstain using selective markers for neurons (e.g. MAP2, bIII-tubulin, NeuN….), astrocytes (e.g. GFAP), microglial cells (CD11b), leukocytes (CD3), macrophages (CD45), blood vessels (e.g. PECAM-1, claudin-5). This could have been easily performed (using a secondary antibody conjugated with Alexa Fluor 555 or better Alexa Fluor 647)  and would have give support to this claim.
    If the author can identify cells by the naked eye, he is either equipped with  Superman X-ray eyes or he is just imagining things.

    The discussion quickly gets into an anti-vaxxer diatribe and throws the minimal amount of scientific data under the bus.
    For example, the author throws this sentence as is: “We recorded some of the highest values for brain aluminium content ever measured in healthy or diseased tissues in these male ASD donors including values of 17.10, 18.57 and 22.11 g/g dry wt. (Table 1).” Firstly, where does it get this data? You cannot sum technical replicates, you have to average them (even with considering the huge variability between technical replicates). Secondly, how can the author make a claim like this without providing values from controls (well there are no controls) or from the literature. It is like “we have recorded the highest amount of leukocytes in ASD patients blood samples with values of 11.3, 12.0 and 11.5 x10e3 cells/mm3.” I cannot make an interpretation or conclusion without knowing the reference from the normal population (normal range 4.5-11x 10e3 cells/mm3) or from control groups. The average Al level was 2.38-4.79 microg/g tissues in male ASD and 1.15 in the female ASD patient. Such levels were very similar to those reported in samples from patients suffering from familial form of Alzheimer’s disease.
    Slide3

    The data is interesting but we are lacking additional female samples to make a claim as he did: “All 4 male donors had significantly higher concentrations of brain aluminium than the single female donor.” He lacks the proper conditions to run the statistics (you need same number of patients in male and female to make such claims) and even the important inter-individual variability makes it unlikely that he could achieve the statistical significance. This is a statement that would put a graduate student in shame for overconfidence in the data.
    Then goes the tirade “What discriminates these data from other analyses of brain aluminium in other diseases is the age of the ASD donors. Why, for example would a 15 year old boy have such a high content of aluminium in their brain tissues? There are no comparative data in the scientific literature, the closest being similarly high data for a 42 year old male with familial Alzheimer’s disease (fAD) [19].” (another Exley paper published…..in the same journal). We are dealing with the same issues (lack of controls, huge variability in the technical replicates…..).
    Now if you plot the average patient Al levels agains the age, regardless of the condition, you end up with an homogenous cloud. Now, two things have to be noted here: seems there is no impact of Al levels based on the disease (only age seems to matter between ASD and AD) and there is no correlation between increase in brain Al and age, at least in the very small sample size.
    Data 2

    No pun intended, but the data scatter looks vaguely like the United States map. Again, it shows the need of data from asymptomatic patients to estimate the burden of Al in the brain.
    Since we have not access to Al content in the brain, we have to see some values in the literature. A study by Andrasi and colleagues (https://content.iospress.com/articles/journal-of-alzheimers-disease/jad00432) provide some Al levels in control samples. According to their study, the average Al content in control samples were between 1.4 to 2.5µg/g dry tissue. We are indeed not far from the value reported by this study, especially when you consider the important standard deviation in these samples.

    Maybe it is also to consider the other study by Exler on Al level in brain samples from patients associated with familial form of Alzheimers disease (fAD) and familial dementia. In that study, all reported with Alzheimers (some with early onset, some with late onset based on age), the Al values reported were ranging from 0.34microg/g tissue (male) to 6.55microg/g (female, presenting a mutation in the PSEN1 gene, a known gene in FAD). So are we just measuring noise and try to extrapolate data from noise? Thats some bold statement that should have been smashed already by a decent reviewer in the field of neurosciences.
    But seeing these two papers went through in a apparent free ride is not looking good for the journal integrity.

  3. Conclusive Remarks
    To make a claim is one thing, to back it up with robust data is another thing. I think Exley jumped the shark a while ago and started to aluminum as the big bad wolf in every little things. But a wolf can be tamed, kept out from showing danger to the community and somehow co-exist. But for Exley, like Shaw, like Gherardi, aluminum is the devil incarnate. God forbid it has been used for 70 years and showed barely more than simple coincidence in its association with some disease, aluminum is their dead horse that worth being beaten again and again. If your funding sponsor will give you money for showing a link between aluminum and autism, lets give them what they want. Ethically it is insane, but when you need to keep your lab and your faculty position afloat, sometimes making the pact with the devil and throwing the scientific integrity and the philosophism that is given to you  following your thesis defense can be tempting. Sometimes, it feels that anti-vaccines researchers are like Faust and succumbed to the offer made by Mephistopheles offer. But this come with a price and a hefty price to pay: the loss of your integrity as a scientist.
    So my question is what is coming next to patients on the spectrum: does this study will be used to support the anti-vaccine agenda (another reason to yell “Aluminum is a chemikillz” in parenting groups?) and breakdown the herd immunity? Bogus remedies by bleach enemas and drops (the infamous CD/MMS)? or give a support to chelation therapy? gluten-free/casein-free diet? Or like Exley once claimed have these people drink ad nauseam silicon-rich water like Fiji water or Volvic water with the magic claims that the silicon with drain your brain from the Al contained inside it?
    This kind of deeply-flawed studies, lacking proper controls and driven by an ideology over the facts are dangerous because they prey on the meek and enrich modern snake oil sellers.

 

[Sciences/BBB] About the Thanksgiving tryptophan comatose and the BBB

Happy Thanksgiving everyone, I hope you are enjoying your family gathering. I know many of you are dreading to meet the family and extended family to discuss about controversial topics and differences in opinion.
But the other big menace coming in, that is particularly feared by the Black Friday shoppers: “The Thanksgiving turkey comatose” myth. This myth is perpetuating the idea that the Thanksgiving feast will induce a lethargic state attributed to the tryptophan present in turkey. Lets use this time to talk about tryptophan, turkey and of course the BBB in all that.

1. What is tryptophan?

Tryptophan is one of the 22 amino acids forming the building bricks of each of our proteins. It belongs to one of the few amino acids that our body cannot produce and therefore has to get it from our food supply.
In addition to its role in proteins, tryptophan is also an interesting molecule for the central nervous system, because it serves as a precursor for serotonin (a neurotransmitter also known as 5-hydroxytryptamine) and melatonin (commonly known as the “clock hormone”). You can see the similarities in structure of these molecules below:
Picture1

Tryptophan is particularly enriched in meat. According to the USDA, turkey meat contains the highest level of tryptophan from all foods, followed by white eggs, soybean and seaweeds. This partly support the claim of turkey being rich in tryptophan.

2. How does the tryptophan enters the central nervous system?

Like you expect, the blood-brain barrier is impermeable to any charged molecule. This is the case of many amino acids circulating in the blood (pH=7.4). Thus amino acids can enter the brain only by using special “revolving door” called solute carriers (SLCs). Tryptophan is transported by a particular amino acid transporter called large amino acid transporter 1 (LAT1). LAT1 is a particular transporter because it is formed by two subunits named SLC3A2 (also named CD98) and SLC7A5.
LAT1 is not specific to tryptophan, it also allows the transport of other aromatic amino acids like phenylalanine and tyrosine, but also chained amino acids such as leucine or arginine.

The impact of dysfunction in LAT1 remains poorly understood, however a study by Mykkaenen and colleagues noted several point mutations in SLC7A7 with a rare disease named lysinuric protein intolerance, a rare autosomal disease primarily described in patients from Finnish and Japanese origin marked by the impaired transport and elimination of basic amino acids following a protein-rich diet.

3. What is the function of tryptophan in the brain?

As I have previously mentioned, tryptophan is the precursor of two major neuromediators: serotonin and melatonin.
Serotonin is produced by a certain type of neurons named “serotoninergic neurons”. Like other neurons expressing a particular neurotransmitter other than glutamate or gamma-aminobutyrate (GABA), these neurons are restricted to a certain localization usually referred as “nucleus” (kernel, core). These neurons can project their axons all through the brain via a process called projections, allowing these neurons to interact with far-fetched neurons localized in a remote location.

In the case of serotoninergic (5-HT) neurons, these neurons are located in a structure called “raphe nucleus” and project to areas in which such neurotransmitter interact with 5-HT receptors. Through the interactions with the receptor, serotonin plays an important role in the modulation of several behavior including appetite, emotional (depression, anxiety), cognitive (schizophrenia) motor and autonomous (for instance emesis, the scientific term of “puking“).

In addition to the biological effects on the brain, the serotonin system is also linked to the circadian rhythm system (what we can call the “biological clock”) as depicted in the picture below:

sadserotoninfigure

We are diurnal animals as our main activity occurs during daylight and concludes with our sleep cycle during the dark period. In opposite, some animals like rodents are nychthemeral animals (active during dark phase and sleeping during daylight).

The light/dark cycle phase is determined by our eyes and retina. Such retina will transmit the presence of light to a particular nucleus named “suprachiasmatic nucleus” (SCN) . This nucleus is consisted by cells and nuclei functioning as oscillators. You can think about a pendulum in perpetual movement or a ticking clock. When darkness settles, the retina start to slowdown the information coming to the SCN.
In turn, the SCN becomes less active and relieve the blockade of the activity of the pineal gland. The pineal gland in turn start to secrete melatonin (aka the sleep hormone) that act as a “negative feedback loop” further shutting down the SCN and stimulate the production of serotonin via the raphe nucleus. All these events ultimately giving us the feeling of being sleepy and the process of sleeping.

4. So why we claim the “turkey comatose” is real?

As you can see in this myth, we are facing a post-hoc ergo fallacy. “I feel sleepy after Thanksgiving dinner. I ate large amount of turkey meat at Thanksgiving dinner. Turkey contains tryptophan and sleep is controlled by melatonin (a tryptophan derivative). Thus the tryptophan contained in the turkey meat is responsible of the food comatose”.

As you have seen, this does not make sense as the sleep/wake cycle is driven by the light exposure. This is also explaining partly why some people feel more tired and less motivated during winter times.

One explanation we can discuss is the particular food intake we all face during Thanksgiving that exceed our usual amount of food. We rarely experience such a feast and copious meal during the year. The table is furnished with so different plates, rich in proteins and carbohydrates.
This create a spike in food intake and food digestion that will likely create a urge of blood flow towards the gastrointestinal tract. This physiological phenomenon is named “postpandrial torpor”, making you feel sleepy and tired after a large meal, even if the meal was completely turkey-free.

So in conclusion, if you want to avoid “the turkey comatose”, don’t blame it on the turkey. Blame it on your eyes having a bigger appetite that your stomach can sustain. Keep it in moderation and now you know about the tryptophan transport at the BBB.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Sciences/Stem Cells] Case report of a successful treatment of a junctional epidermolysis bullosa (Hirsch et al., Nature 2017)

This is a very groundbreaking case report here on a patient suffering from junctional epidermolysis bullosa (JEB). This is a genetic condition marked by mutation in the LAMB2 gene, a gene encoding for laminin beta-2 chain of the laminin complex. Laminins are part of the extracellular matrix and play an important role in cell adhesion such as skin cells. Imagine a concrete slab by which your house sits firmly.
In patients suffering from JEB, this slab is wobbly and crackle under the pressure due to some issues in the concrete composition. These patients end up having a very fragile skin that rapidly detach and have a low life expectancy due to high risk of infection and important handicap. Until now, no treatment has been successful, including skin grafts.
In this case report, the authors have taken skin stem cells from this patient and have corrected the mutation by inserting a correct gene copy of LAMB2 via retrovirus. Such stem cells were maintained and expanded into Petri dishes to form skin graft islands. Such islands where then implanted to the patients and successfully grafted in. Apparently the patient has been able to recover and live an almost normal life.
Another “Yes!” moment for science! If you are interested to read more about it, you can find it here:
https://www.nature.com/articles/nature24487