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Showing posts with label BH4. Show all posts
Showing posts with label BH4. Show all posts

Sunday 24 September 2017

Hypoperfusion in Autism Revisited


One old post from this blog has been going viral recently (3,000 views in one day, via Facebook) and it is quite relevant to a debate that has been going on in the comments about the potential merits and mechanisms of Hyperbaric Oxygen Therapy (HBOT). Two commenters are big fans of HBOT.
Hypoperfusion is reduced blood flow, which is found in some people with autism and also in people with some types of dementia  
Having reread my old post I would recommend it to those who are looking into the treatment of brain damage caused by ischemia. 


While much in neuroscience is extremely complicated, there are some pretty basic things to consider that are not. Adequate blood supply is one of the basic issues and is something that can be improved.
You can increase blood flow by reducing vascular resistance, which means reducing the work the heart has to do to circulate blood around the body. As you reduce this resistance, blood pressure will fall, but that does not mean the flow rate of blood has reduced, it just means it is circulating more freely.
You can measure cerebral blood flow and this is how researchers know that it can be abnormal in autism.
As I noted in the old post above, HBOT is one therapy proposed by some. Using an MRI you could establish with certainty if HBOT was effective in any particular individual, in regard to increasing cerebral blood flow.
I think there will be many ways to improve perfusion in an affected individual. Without a particular type of MRI you cannot really know for sure if your case of autism is one of these.
The dementia research pointed me towards cocoa flavanols, which seem to affect nitric oxide (NO), but do not directly produce it.
Nitric oxide (NO) is very important in the body and one of its roles is vasodilation (widening of blood vessels).
Some people believe that nootropic drugs work by vasodilation, i.e. more blood flow increases cognitive function.  I think that this is one of many possible ways to improve cognition, which will work in some people, but not others. 
To understand Nitric oxide (NO) you have to go a little deeper and look at eNOS (endothelial nitric oxide synthase), iNOS (inducible NO synthase) and nNOS (neuronal NO synthase). Nitric oxide can be very good for you, but it can also be very bad for you.  The short version is that Nitric oxide (NO) production by endothelial nitric oxide synthase (eNOS) plays a protective role in maintaining vascular permeability, whereas NO derived from neuronal and inducible NOS is neurotoxic and can participate in neuronal damage occurring in ischemia.,
For a thorough explanation here is a highly cited paper:-


Endothelial NOS (eNOS, NOS III) is mostly expressed in endothelial cells. It keeps blood vessels dilated, controls blood pressure, and has numerous other vasoprotective and anti-atherosclerotic effects. Many cardiovascular risk factors lead to oxidative stress, eNOS uncoupling, and endothelial dysfunction in the vasculature. Pharmacologically, vascular oxidative stress can be reduced and eNOS functionality restored with renin- and angiotensin-converting enzyme-inhibitors, with angiotensin receptor blockers, and with statins. 


Statins are already in my Polypill. Telmisartan seemed to be the most likely ACE inhibitor or ARB (angiotensin receptor blocker) to help some autism, when I reviewed them in a previous post. Telmisartan produced more singing, as does Agmatine (see below).

Now look at how NO is produced by eNOS:-

           https://en.wikipedia.org/wiki/Endothelial_NOS 

“In the vascular endothelium, NO is synthesized by eNOS from L-arginine and molecular oxygen, which binds to the heme group of eNOS, is reduced and finally incorporated into L- arginine to form NO and L-citrulline. The binding of the cofactor BH4 is essential for eNOS to efficiently generate NO. In the absence of this cofactor, eNOS shifts from a dimeric to a monomeric form, thus becoming uncoupled. In this conformation, instead of synthesizing NO, eNOS produces superoxide anion, a highly reactive free radical with deleterious consequences to the cardiovascular system.

BH4 (Tetrahydrobiopterin/Kuvan) is one of substances that comes up in autism research from time to time.  You would not want to be deficient in BH4 and if you have autism and BH4 deficiency you have a very obvious therapy.   


A good article, surprisingly from the UK Financial Times, which they ask not to be cut and paste, so I have not. Take a look.

If Kuvan lights up the brain, as Dr Frye suggested in the above FT article, I wonder what else can, in those people.  L-arginine might help, or perhaps its metabolite Agmatine, as used by our reader Tyler.
If you read the quite complicated paper below you will see that, in rats at least, Agmatine increases eNOS, while reducing  iNOS. 
You compare EC6 (experimental control after 6 hours) with Agm6 (Agmatine after 6 hours) and then EC24 with Agm24. 




Effects of eNOS and iNOS expression by agmatine treatment following transient global ischemia in rat hippocampus. Representative expressional levels of eNOS (A) and iNOS (C) at 6 h after agmatine treatment (100 mg/kg, i.p), and densitometric data (B, D). Data represent means±SD for n=5/NC, n=3/EC and Agm group per each time point. *


Cost

BH4/Kuvan/Sapropterin is rather expensive, but people do use it off-label in autism.  It is the only FDA-approved medication for Phenylketonuria (PKU) to reduce blood Phe levels in patients with hyperphenylalaninemia (HPA) due to tetrahydrobiopterin (BH4-) responsive PKU.

http://www.biomarin.com/products/kuvan

PKU is one of those rare inborn errors of metabolism that lead to intellectual disability/MR and, not surprisingly, also autism. It is included in my Treatable ID tab at the top of every page.  The link will take you here  http://www.treatable-id.org/page36/Phenylketonuria.html

Agmatine is cheap and does have an almost immediate positive effect in some people with autism.

Do people who respond to BH4 respond to Agmatine and vice versa?
Agmatine does have many other modes of action, other than increasing eNOS and reducing iNOS.
I have been experimenting with Agmatine, and while Dr Frye suggests Kuvan can “light up the brain”, my impression of Agmatine brings the Energizer(US)/Duracell (Europe) Bunny to mind.


A daily dose of Agmatine is like having better battery in your toy bunny, at least in my house.  It is also associated with more singing.
Judging from Tyler’s comments perhaps he is seeing the same magnitude of effects that Dr Frye attributes to Kuvan.   





Thursday 8 December 2016

Nitrosative Stress, Nitric Oxide and Peroxynitrite










In this example of Brain Injury, developing oligodendrocytes are injured and killed by substances released from activated microglia, including nitric oxide and superoxide, which form peroxynitrite. Peroxynitrite has been found to kill these cells through the activation of the 12-lipoxygenase pathway for metabolizing arachidonic acid. Mitochondria may be involved in this pathway as a source of reactive oxygen species.


Much has been written in this blog about oxidative stress, which has now been extremely well researched in autism and more generally. Let’s recap oxidative stress.

The most knowledgeable researcher in this area is Abha Chauhan.  Based on her research and that of others we now know a great deal.  Recall that the body’s key antioxidant is called glutathione (GSH) and when it neutralizes a free radical GSH is converted to its oxidized form, glutathione disulfide (GSSG).  A good measure of oxidative stress is the ratio of  GSH/GSSG.


·        Autism is associated with deficits in glutathione antioxidant defence in selective regions of the brain.

·        In the cerebellum and temporal cortex from subjects with autism, GSH levels are significantly decreased by 34.2 and 44.6 %, with a concomitant increase in the levels of GSSG

·        There is also a significant decrease in the levels of total GSH (tGSH) by 32.9 % in the cerebellum, and by 43.1 % in the temporal cortex of subjects with autism.

·        In contrast, there was no significant change in GSH, GSSG and tGSH levels in the frontal, parietal and occipital cortices in autism

·        The redox ratio of GSH to GSSG was also significantly decreased by 52.8 % in the cerebellum and by 60.8 % in the temporal cortex of subjects with autism, suggesting glutathione redox imbalance in the brain of individuals with autism.

·        Disturbances in brain glutathione homeostasis may contribute to oxidative stress, immune dysfunction and apoptosis, particularly in the cerebellum and temporal lobe, and may lead to neurodevelopmental abnormalities in autism.


·        The activity of glutathione cysteine ligase (GCL), an enzyme for glutathione synthesis is impaired in autism.

·        The protein expression of its modulatory subunit GCLM was decreased in autism.

·        The activities of glutathione peroxidase (GPx) and glutathione S-transferase were decreased in autism.



For those interested, GPx is a family of enzymes that catalyze the reaction that converts GSH to GCCG.  So in order to soak up those free radicals you need both GSH and GPx.

Glutathione cysteine ligase (GCL) is a key enzyme needed to make the antioxidant GSH.  Dysregulation of GCL enzymatic function and activity is known to be involved in many human diseases, such as diabetes, Parkinson's disease, Alzheimer’s disease, COPD, HIV/AIDS, cancer and autism.  Without sufficient GCL your body cannot make enough glutathione (GSH).


I did have some conversation with Abha Chauhan a few years ago when I found that NAC (N-acetyl cysteine), a known precursor to GSH, really does have a positive behavioral impact in autism.  She is clearly very nice, but not the type to make the leap to translating her science into therapy.

As I have shown there are many other treatable aspects of oxidative stress.

The chart below is my annotated version of the original by Professor Helmut Sies, the German “Redox Pioneer”.  He has published 500 scientific papers.




Nitrosative Stress


Finally to nitrogen.

Nitrogen is the most common pure element in the earth, making up 78.1% of the entire volume of the atmosphere.  Although nitrogen is non-toxic, when released into an enclosed space it can displace oxygen, and therefore presents an asphyxiation hazard. 

Nitrogen is an anesthetic agent. Nitrous oxide (N2O) is commonly known as laughing gas.  It is used in medicine for its unaesthetic and analgesic effects

It is also used as an oxidizer in rocket propellants, and in motor racing to increase the power output of engines, like Mad Max.

In humans we are dealing with Nitric Oxide (NO) and when things go wrong with peroxynitrite and then other Reactive nitrogen species (RNS).  In simple terms Reactive nitrogen species (RNS), like Reactive oxygen species (ROS) are bad news.

Nitric Oxide (NO) itself does lots of good things in your body.  Too much may not be good, but a little more can actually do you good.  NO is a potent vasodilator.

For over 130 years, nitroglycerin has been used to treat heart conditions, such as angina and chronic heart failure.  Nitroglycerin produces nitric oxide (NO). In hospital most patients will receive nitroglycerin during and after a heart attack, people at risk of a heart attack often carry nitroglycerin with them.

If you want to lower your blood pressure or an athlete wanting to legally improve exercise endurance you can increase Nitric Oxide (NO) via diet.  One easy way is to drink beetroot juice, as is common in endurance cycling.  In people with peroxynitrite-derived radicals this may be unwise, because they may have too much NO.



Peroxynitrite

The starting point for the production of those unhelpful Reactive Nitrogen Species (RNS) is this chemical reaction



NO (nitric oxide) + O2· (superoxide) → ONOO (peroxynitrite)



NO production is affected by the enzyme nitric oxide synthase 2 (NOS2).

Superoxide production is catalyzed by NADPH oxidase.

Superoxide also produces Reactive Oxygen Species (ROS).

NADPH oxidase is implicated in many diseases including schizophrenia and autism.

NADPH oxidase 4 (Nox4) activity decreases mitochondrial function (chain complex I).

Activated microglia (as found in autism) produce both nitric oxide and superoxide and are therefore a source of peroxynitrite.




This has started to get rather complicated. So those interested in NADPH should refer to the literature.


Peroxynitrite can directly react with various biological targets and components of the cell including lipids, thiols, amino acid residues, DNA bases, and low-molecular weight antioxidants.


Additionally peroxynitrite can react with other molecules to form additional types of RNS including nitrogen dioxide (·NO2) and dinitrogen trioxide (N2O3) as well as other types of chemically reactive free radicals.



Nitric Oxide and Peroxynitrite in Health and Disease

I have referred on this blog to Abha Chauhan’s mammoth book on oxidative stress in autism on several occasions.  A work of similar quality but this time on Nitric Oxide and Peroxynitrite, is the paper below, by Hungarian Pal Pacher, who works at the US National Institute of Health’s Section on Oxidative Stress Tissue Injury.  He looks like a citation generating machine.

You could spend a long time reading this paper, but in summary peroxynitrite and its derived products have a negative effect on a very wide range of conditions including all the common neurological conditions, inflammatory diseases and again diabetes.  The answer would be peroxynitrite scavengers.



The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.


Some excerpts:-


·        The different events set in motion by the initial generation of peroxynitrite indicate that potent peroxynitrite decomposition catalysts and PARP inhibitors might represent useful therapeutic agents for debilitating chronic inflammatory diseases

·        In summary, available evidence indicates that NO plays dichotomous roles (promotion vs. suppression) in tumor initiation and progression. The activation of angiogenesis and the induction of DNA mutations represent key aspects of the procarcinogenic effects of NO. Peroxynitrite is emerging as a major NO-derived species responsible for DNA damage, mainly through guanine modifications and the inhibition of DNA repair enzymes. In chronic inflammatory states, the identification of 8-nitroguanine in tissues indicates that nitrative DNA damage consecutive to overproduction of NO and peroxynitrite may represent an essential link between inflammation and carcinogenesis.

·        In summary, the different studies listed above indicate that small amounts of NO produced by eNOS in the vasculature during the early phase of brain ischemia are essential to limit the extent of cerebral damage, whereas higher concentrations of NO, generated initially by nNOS and later by iNOS, exert essentially neurotoxic effects in the ischemic brain. Evidence that such toxicity depends, in large part, on the rapid reaction of NO with locally produced superoxide to generate peroxynitrite will be now exposed
  

·        NO is produced by all brain cells including neurons, endothelial cells, and glial cells (astrocytes, oligodendrocytes, and microglia) by Ca2+/calmodulin-dependent NOS isoforms. Physiologically NOS in neurons (nNOS, type I NOS) and endothelial cells (eNOS, type III NOS) produce nanomolar amounts of NO for short periods in response to transient increases in intracellular Ca2+, which is essential for the control of cerebral blood flow and neurotransmission and is involved in synaptic plasticity, modulation of neuroendocrine functions, memory formation, and behavioral activity (491, 890, 1229). The brain produces more NO for signal transduction than the rest of the body combined, and its synthesis is induced by excitatory stimuli. Consequently, NO plays an important role in amplifying toxicity in the CNS. Indeed, under various pathological conditions associated with inflammation (e.g., neurodegenerative disorders and cerebral ischemia), large amounts of NO are produced in the brain as a result of the induced expression of iNOS (type II NOS) in glial cells, phagocytes, and vascular cells, which can exert various deleterious roles (39, 491, 890). Thus NO may be a double-edged sword, exerting protective effects by modulating numerous physiological processes and complex immunological functions in the CNS on one hand and on the other hand mediating tissue damage (446, 491, 890). The detailed discussion of the role of NO in the pathophysiology of various neurodegenerative disorders including Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS), just mentioning a few, is the subject of numerous excellent recent overviews (77, 145, 194, 219, 491, 890, 1003, 1205, 1433) and beyond the scope of this paper. Here we cover only the role of peroxynitrite and protein nitration, which are likely responsible for most deleterious effects of NO in neurodegenerative disorders.


·        Peroxynitrite formation has been implicated in Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, MS, ALS, and traumatic brain injury (reviewed in Refs. 194, 608, 1119, 1284). Nitrotyrosine immunoreactivity has been found in early stages of all of these diseases in human autopsy samples as well as in experimental animal models. Increased nitrite, nitrate, and free nitrotyrosine has been found to be present in the cerebral spinal fluid (CSF) and proposed to be useful marker of neurodegeneration (168; reviewed in Refs. 608, 1119, 1284). Once formed in the diseased brain, peroxynitrite may exert its toxic effects through multiple mechanisms, including lipid peroxidation, mitochondrial damage, protein nitration and oxidation, depletion of antioxidant reserves (especially glutathione), activation or inhibition of various signaling pathways, and DNA damage followed by the activation of the nuclear enzyme PARP (608, 1119, 1284).


·        Uric acid has proven to be a useful inhibitor of tyrosine nitration (although it is not a direct peroxynitrite scavenger) (1271) and has been shown to protect the blood-brain barrier and largely prevent the entry of inflammatory cells into the CNS (566, 567). Additionaly, it also prevented CNS injury after inflammatory cells have already migrated into the CNS (1141). Urate has also proven beneficial in reducing the morbidity associated with viral infections (710, 1141). Interestingly, in humans there is an inverse correlation between affliction with gout and MS (710, 1195). Numerous studies have reported lower levels of uric acid in MS patients favoring the view that reduced uric acid in MS is secondary to its “peroxynitrite scavenging” activity during inflammatory disease, rather than a primary deficiency (reviewed in Ref. 694). These studies have also suggested that serum uric acid levels could be used as biomarkers for monitoring disease activity in MS

  

·        Recent evidence suggests that mitochondrial complex I inhibition may be the central cause of sporadic PD and that derangements in complex I lead to α-synuclein aggregation, which contributes to the demise of dopamine neurons (293). Accumulation and aggregation of α-synuclein may further facilitate the death of dopamine neurons through impairments in protein handling and detoxification (293). As already mentioned above, both mitochondrial complex I and synuclein can be targets for peroxynitrite-induced protein nitration


·        The significance of this intricate interplay may have important ramifications not only for ALS but also for PD and AD (6, 58, 1102). Reactive astrocytes are common hallmark of neurodegeneration, and these results suggest that peroxynitrite may play an important role in promoting this phenotype as well as causing the degeneration of neurons. In ALS, the transformation of astrocytes into a reactive phenotype may explain why ALS is progressive, causing the relentless death of neighboring motor neurons. Interfering in such a cascade to stop the progressive death of motor neurons would not necessarily cure ALS but may keep it from being a death sentence.


·        There is accumulating evidence suggesting that increased oxidative stress and excessive production of NO might contribute to the development of HD by damaging neighboring neurons (reviewed in Refs. 63, 163). Accordingly, increased iNOS expression was observed in neuronal, glial, and vascular cells from brains of HD patients and mouse models of disease (206, 491). Similarly, numerous studies have demonstrated increased 3-NT formation in brain tissues (neurons, glia, and/or vasculature) of mice transgenic for the HD mutation, rats injected into the striatum with quinolinic acid (rat model of HD), and HD patients (300302, 427, 1022, 1023, 1096, 1117). Importantly, both NOS inhibitors and peroxynitrite scavengers decreased neuronal damage, improved disease progression, and also decreased brain 3-NT content in experimental models (301, 1022, 1117). These results suggest that peroxynitrite might be an important mediator of oxidative damage associated with HD.


·        The pathogenetic role of peroxynitrite in TBI is supported by evidence demonstrating increased brain 3-NT levels following TBI in experimental mouse and rat models (9294, 423, 507, 508, 898, 1171, 1360), and by the beneficial effects of NOS inhibitor and peroxynitrite scavengers in reducing neuronal injury and improving neurological recovery following injury (423, 508, 898).Collectively, multiple lines of evidence discussed above provide strong support for the important role of peroxynitrite formation and/or protein nitration in neurodegenerative disorders and suggest that the neutralization of this reactive species may offer significant therapeutic benefits in patients suffering from these devastating diseases.


·        Collectively, the evidence reviewed above support the view that peroxyntrite-induced damage plays an important role in numerous interconnected aspects of the pathogenesis of diabetes and diabetic complications. Neutralization of RNS or inhibition of downstream effector pathways including PARP activation may represent a promising strategy for the prevention or reversal of diabetic complications.

·        In conclusion, multiple lines of evidence discussed above and listed in Table 4 suggest that peroxynitrite plays an important role in various forms of cardiovascular dysfunction and injury; pharmacological neutralization of this reactive oxidant or targeting the downstream effector pathways may represent a promising strategy to treat various cardiovascular disorders.


·        In summary, circulatory shock is a leading cause of death in intensive care units. Considerable improvement in our understanding of the molecular and cellular mechanisms of shock over the past 20 years makes it now a reasonable expectation that novel, efficient mechanism-based therapies will emerge in the near future. Considerable evidence now exists that overproduction of NO and superoxide, triggering the generation of large amounts of peroxynitrite, is a central aspect of shock pathophysiology. In addition to direct cytotoxic effects such as the peroxidation of lipids, proteins, and DNA, peroxynitrite also occupies a critical position in a positive feedback loop of inflammatory injury, by (directly or indirectly, via PARP activation) activating proinflammatory signaling and by triggering the recruitment of phagocytes within injured tissues, leading to further NO, superoxide, and peroxynitrite production, which will progressively amplify the initial inflammatory reactions (see sect. VID, Fig. 14). These various observations support the view that future strategies reducing peroxynitrite or its precursors might have a considerable therapeutic impact in clinical circulatory shock.


Peroxynitrite Scavengers


We have already covered two substances in this blog that are potential Peroxynitrite Scavengers:-


Calcium Folinate

This is Roger’s magic pill to treat his Cerebral Folate Deficiency, but it may have application far beyond this, likely rare, condition, for those that tolerate it.

Tetrahydrofolic acid, or tetrahydrofolate, is a folic acid derivative. It has the potential to quench those peroxynitrite-derived radicals.




The presumed protective effect of folic acid on the pathogenesis of cardiovascular, hematological and neurological diseases and cancer has been associated with the antioxidant activity of folic acid. Peroxynitrite (PON) scavenging activity and inhibition of lipid peroxidation (LPO) of the physiological forms of folate and of structurally related compounds were tested. It was found that the fully reduced forms of folate, i.e. tetrahydrofolate (THF) and 5-methyltetrahydrofolate (5-MTHF), had the most prominent antioxidant activity. It appeared that their protection against LPO is less pronounced than their PON scavenging activity. The antioxidant activity of these forms of folic acid resides in the pterin core, the antioxidant pharmacophore is 4-hydroxy-2,5,6-triaminopyrimidine. It is suggested that an electron donating effect of the 5-amino group is of major importance for the antioxidant activity of 4-hydroxy-2,5,6-triaminopyrimidine. A similar electron donating effect is probably important for the antioxidant activity of THF and 5-MTHF.


Uric Acid

Uric acid has proven to be a useful inhibitor of tyrosine nitration.  It was thought to be a scavenger of peroxynitrite, but our clever Pal from Hungary tells thatit is not a direct peroxynitrite scavenger ….Numerous studies have reported lower levels of uric acid in MS patients favoring the view that reduced uric acid in MS is secondary to its “peroxynitrite scavenging” activity during inflammatory disease, rather than a primary deficiency”.

An old paper:-



Uric acid, the naturally occurring product of purine metabolism, is a strong peroxynitrite scavenger, as demonstrated by the capacity to bind peroxynitrite but not nitric oxide (NO) produced by lipopolysaccharide-stimulated cells of a mouse monocyte line. In this study, we used uric acid to treat experimental allergic encephalomyelitis (EAE) in the PLSJL strain of mice, which develop a chronic form of the disease with remissions and exacerbations. Uric acid administration was found to have strong therapeutic effects in a dose-dependent fashion. A regimen of four daily doses of 500 mg/kg uric acid was required to promote long-term survival regardless of whether treatment was initiated before or after the clinical symptoms of EAE had appeared. The requirement for multiple doses is likely to be caused by the rapid clearance of uric acid in mice which, unlike humans, metabolize uric acid a step further to allantoin. Uric acid treatment also was found to diminish clinical signs of a disease resembling EAE in interferon-γ receptor knockout mice. A possible association between multiple sclerosis (MS), the disease on which EAE is modeled, and uric acid is supported by the finding that patients with MS have significantly lower levels of serum uric acid than controls. In addition, statistical evaluation of more than 20 million patient records for the incidence of MS and gout (hyperuricemic) revealed that the two diseases are almost mutually exclusive, raising the possibility that hyperuricemia may protect against MS.



Here we have a paper with the link to Tetrahydrobiopterin (BH4,), also known as sapropterin, covered in an old post:-




Interactions of peroxynitrite with uric acid in the presence of ascorbate and thiols: Implications for uncoupling endothelial nitric oxide synthase

It has been suggested that uric acid acts as a peroxynitrite scavenger although it may also stimulate lipid peroxidation. To gain insight into how uric acid may act as an antioxidant, we used electron spin resonance to study the reaction of uric acid and plasma antioxidants with ONOO-. Peroxynitrite reacted with typical plasma concentrations of urate 16-fold faster than with ascorbate and 3-fold faster than cysteine. Xanthine but not other purine-analogs also reacted with peroxynitrite. The reaction between ONOO- and urate produced a carbon-centered free radical, which was inhibited by either ascorbate or cysteine. Moreover, scavenging of ONOO- by urate was significantly increased in the presence of ascorbate and cysteine. An important effect of ONOO- is oxidation of tetrahydrobiopterin, leading to uncoupling of nitric oxide synthase. The protection of eNOS function by urate, ascorbate and thiols in ONOO(-)-treated bovine aortic endothelial cells (BAECs) was, therefore, investigated by measuring superoxide and NO using the spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine (CMH) and the NO-spin trap Fe[DETC]2. Peroxynitrite increased superoxide and decreased NO production by eNOS indicating eNOS uncoupling. Urate partially prevented this effect of ONOO- while treatment of BAECs with the combination of either urate with ascorbate or urate with cysteine completely prevented eNOS uncoupling caused by ONOO-. We conclude that the reducing and acidic properties of urate are important in effective scavenging of peroxynitrite and that cysteine and ascorbate markedly augment urate's antioxidant effect by reducing urate-derived radicals.


Xanthine oxidase (XO, sometimes 'XAO') is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species.[2] These enzymes catalyze the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid. These enzymes play an important role in the catabolism of purines in some species, including humans.





Because xanthine oxidase is a metabolic pathway for uric acid formation, the xanthine oxidase inhibitor allopurinol is used in the treatment of gout.


Inhibition of xanthine oxidase has been proposed as a mechanism for improving cardiovascular health.  A study found that patients with chronic obstructive pulmonary disease (COPD) had a decrease in oxidative stress, including glutathione oxidation and lipid peroxidation, when xanthine oxidase was inhibited using allopurinol.


Reactive nitrogen species, such as peroxynitrite that xanthine oxidase can form, have been found to react with DNA, proteins, and cells, causing cellular damage or even toxicity. Reactive nitrogen signaling, coupled with reactive oxygen species, have been found to be a central part of myocardial and vascular function, explaining why xanthine oxidase is being researched for links to cardiovascular health.


We also should recall that abnormalities are common in autism.





So perhaps allopurinol for those with too much uric acid?  Perhaps this is a good marker for peroxynitrites ?





Conclusion

As is often the case there some contradiction in the science.  Is NO good for you or not?  Are both high and low uric acid actually indicating the same biological problem.

It looks like the research into very expensive BH4 therapy might be better directed into peroxynitrite scavengers.

I think we have found the reason why so many people with autism respond to Leucovorin (calcium folinate) and, unlike in our friend Roger, it may not be because of cerebral folate deficiency.

It looks like many other chronic conditions from diabetes to COPD to schizophrenia might also benefit from  calcium folinate.

Before I forget, in the Helmut Sies oxidative stress graphic I did highlight selenium.  The GPx enzymes contain selenium and if there is selenium deficiency the body's key antioxidant mechanism will be compromised. According to Abha Chauhan's book,  "Likewise, levels of exogenous antioxidants were also found to be reduced in autism, including vitamin C, vitamin E, and vitamin A in plasma, and zinc and selenium in erythrocytes (James et al., 2004)".  This might suggest adding a little extra selenium.

I think Allopurinol is worth a look for some autism.  Allopurinol does indeed reduce reactive nitrogen species in COPD (severe asthma), as suggested above.



“These results suggest that oral administration of the xanthine oxidase inhibitor allopurinol reduces airway reactive nitrogen species production in chronic obstructive pulmonary disease subjects. This intervention may be useful in the future management of chronic "









Saturday 13 July 2013

Endothelial Dysfunction - Oxidative Stress, Inflammation and BH4

This post is rather out of sequence, but it draws together several different topics that I have been investigating and introduces another chemical often mentioned in autism research, BH4.  The factor that links them all together is something called Endothelial Dysfunction.

This blog has already established that oxidative stress and neuroinflammation are the key drivers behind autism.  It has not been clear whether the oxidative stress causes the inflammation, vice versa, or perhaps they are self perpetuating.

In my ongoing investigation into the autism comorbidities of asthma and high cholesterol (proxy for cardiovascular disease), I have come across some tantalising fact, such as:-
  • Asthma research shows that cigarette smoking gives you oxidative stress and this continues even after stopping smoking.  The oxidative stress reduces the effectiveness of asthma drugs.
  • Oxidative stress is a key factor in cardiovascular disease.
  • BH4 also known as Tetrahydrobiopterin, THB, trade name Kuvan or sapropterin is an enzymatic cofactor that is the subject of lots of research in cardiovascular disease and even in autism research.  As a drug, BH4 is so expensive that many national health services and insurers will not pay for it.  A pack of 30 pills of 100 mg cost $900.  The typical dose is 10-20mg per kg per day.  The cost per patient was reported to be over $100,000 per year.

The BH4 drug, Kuvan, is used to treat an extremely rare, but debilitating condition called Phenylketonuria, when the body cannot produce its own BH4.  In the UK, the National Health Service will not pay for Kuvan for the very small number of people who suffer Phenylketonuria.


A very interesting chart from the American Heart Association

The following chart was meant for cardiologists, but is extremely relevant if you want to understand autism.  I highlighted the parts in yellow.

























In autism, people suffer from oxidative stress and typically exhibit hypercholesterolemia (high cholesterol).  They also suffer from neuroinflammation in the brain.  In my therapy, I use NAC to reduce oxidative stress and the behavioral impact is very marked.  In some autism trials they have given BH4 and the result have been visible, but not dramatic.  From the graphic above it would seem that BH4 is an extremely expensive way to reduce oxidative stress.

The latest BH4 autism trial was funded by the drug producer with 20 mg/kg/day.
 

More interesting for me is to now look into Endothelial Dysfunction and see if that is occurring in autism.











Monday 25 March 2013

Nela and the Magic Flute

Nela is Monty’s excellent assistant at school, but today, because he is a bit sick, she came to Monty’s house instead.  Nela also has her own theatre school, which she runs in the afternoons.  Monty loves the theatre, and the curtains in particular.

Shortly after Nela arrived at our house, she said “Monty is going to see the Magic Flute”.

So how did Nela know that Monty is going to the opera (albeit the children’s version)?  Well, Monty told her, of course.  Now this might not sound much to you, but for me that is worthy of a big WOW.  Autistic kids are not big conversationalists at the best of times.   Even stranger, said Nela, was that he was really talkative all morning.

Now when his brother Ted is sick, it is about the only time he ever stops talking.

Then I said to Nela, actually it’s not strange at all; it is a proven fact that when autistic kids have a temperature they behave more “normal”.  I said that I would write about in my blog, so now I have to. I was actually saving this for a later post, when I set out the “Peter hypothesis of TRH induced homeostasis in autism”.
 

The post I originally intended to write

But, first a quick detour.  For those serious scientists among you, there is an excellent blog that you should take a look at.  It is written by a professional autism researcher, Paul Whitely.  The blog is called Questioning-Answers.

Now, late last night I was looking at Paul’s blog and reading all about something called tetrahydrobiopterin (also known as BH4 ,THB, trade name Kuvan, or even sapropterin) and how it might be a useful drug to treat autism.  Then I looked at his links to the research papers and then I looked at the citations listed in those papers; it looked like another long session on Google might lie ahead.  Then, I concluded that since people have been talking about BH4 and autism for 24 years; somebody should have done a serious controlled study by now.  So I will wait until they do, before getting out my textbooks.  Actually, by reading the label (the citations at the bottom of the study) I saw the following at number 53:-
 
53.  Klaiman C, Huffman L, Elliott GR. Sapropterin as a treatment for Autism Spectrum Disorders: a double-blind, placebo-controlled trial. J Child Adol Psychop 2013 (in press).

So after 24 years, it looks like someone has finally done a serious study.  I expect in a month or so it will appear on Paul’s blog, then I will take a good look.


Back to the Opera

So as not to disappoint Nela, let’s get back to business.  When I started this blog I was going to match my observations of Monty’s quirky behaviours to some solid science.  One observation was that whenever he stayed home sick, he was always great at his piano lesson, and with me on Whizz.com, the maths program, or doing literacy/numeracy with his assistant.

So applying some ANA, I found that the American Academy of Pediatrics (Americans spell it like that) had published a study called:-


They concluded that it is indeed true; a fever makes you less autistic; but why ?

They put forward five possible reasons:- 

(1)  neurobiological effects of selected pro-inflammatory and/or anti-inflammatory cytokines, which have been found to be increased in cerebrospinal fluid (in the absence of fever) and postmortem brain tissue of individuals with autism and may be generated during different phases of responses to fever,  

(2)  modification of neuronal and synaptic function secondary to variations in body temperature that influence neural conduction velocities or synaptic transmission,  

(3)  modification of dynamic neural networks as a result of changes in cellular signal transduction and gene transcription that regulate synapse formation and function, 

(4)  increased production of other stress-related proteins, such as heat-shock proteins, during fever that might modify energy consumption and mitochondrial activity  

(5)  stimulation of the hypothalamic-pituitary-adrenal axis leading to modifications of neurotransmitter production and interaction.
 
And noted:- 

Should any of these mechanisms be proved to effect behavior changes in individuals with ASDs, this would stimulate research on potential treatments focused on these pathways.

Well this was another of my Eureka moments, since reason (5) fits very neatly with my TRH hypothesis, which was again based on other observations of Monty’s behavior.

For now, at least Paul and Nela will be intrigued; the rest of you may be bemused.  All will be revealed shortly, when my I finish my TRH project.

Now, as Monty would say,  “curtains close”.