Wednesday, May 20, 2015

Polyprenyl derivatives at the origin of life

I just wanted to put something down about the possible early membranes used by LUCA. There is a good case to be made for leaky membranes (certainly to protons) composed of polyprenyl phosphates. Here's the logic:

Start with the modern mevalonate pathway, from wiki.
















Now, let's butcher it down to its utter basics:



Isopentenyl pyrophosphate is the central cornerstone of polyprenyl phosphate generation by this reaction:


















You can make the polyprenyl phosphate lipid as long as you like, just add more isopentenyl derived units. This gives us the entry point, top centre, for this diagram:

















Down the left hand side we have the simple pathway to the archeal plasma membranes, as you might expect. Down the centre is the route to cholesterol, essential to animal cell membranes. The hopanoids, essential to bacteria but absent from archea, are left of centre.

Archea stayed with polyprenyls for their membrane, bacteria went for the fatty acids while retaining polyprenyl derived components. Derivatives of polyprenyls are ubiquitous. Metabolic cornerstones common to both archea and bacteria may well have been present in LUCA. Seems a reasonable argument to me.

There are a set of core enzymes present in both archea and bacteria which appear to have evolved before their divergence from LUCA. Perhaps the most significant is the rotator/stator ATP synthase, a piece of molecular nanotechnology of breathtaking complexity, considering that it appears to have evolved as one of the core early molecular machines of life. It's association with membranes suggest that membranes were there quite early on in evolution.

The presence of membranes allows us to think about some interesting questions. Such as why are cells powered by ATP? Because that is what ATP synthase produces. There is nothing intrinsically special about ATP. Reduced ferredoxin is a common power source in bacteria and archaea. Acetyl phosphate can be used too. But ATP is what is made by the ATP synthase machine and it can be produced in bulk, given a membrane potential. The hows and whys are interesting.

Peter

The Wall is coming down

Well, I guess it's going to become officially OK (as if I could care less) for me to fry my egg yolks in salted butter and add a little extra salt at serving time. And to skip any sugar in my tea. At the risk of glucose deficiency I suppose but, what the hell, live dangerously...

Malcolm Kendrick and Steve Cooksey have two nice accounts (amongst many) out there so there's not much for me to add. It just reminds me of listening to the news as the Berlin Wall came down, even if it's not headlining at the BBC yet. Amazing. Happy.

You still have to feel sorry for the people so badly injured by the consequences of the lipid hypothesis but at least the possibility of using real food to produce normoglycaemia is no longer specifically decried by official dietary advice. The floodgates are open. The information is out there.

Excellent.

Peter

BTW, the Japanese appear to be about to start the destruction of statination too, certainly for the elderly... Thanks to Liz for the full text link.

Tuesday, May 19, 2015

Prokaryotic Microbes with Eukaryote-like Genes Found

Jack Kruse sent me this link:

Archaea with eukaryotic genes

For those working through Nick Lanes latest book will realise (if you hadn't already!) that there is an energetic cost to everything. The ability to change shape at will, with a view to phagocytosis, is both an essential to the development of the eukaryotes and is energetically very costly.

In the absence of mitochondria the only place this appears to have been discovered is the deep sea alkaline hydrothermal vents, in this case at Loki's Castle. This is the environment where geothermal sources generate the electrochemical disequilibrium which probably got life started using the "free lunch" of CO2/CO plus R-SH giving acetyl-S-R, gateway to metabolism. It is still an energy rich environment.

Phagocytosis is costly.

The alpha proteobacterial precursor of our mitochondria had to get inside the archaeal host. This is an interesting discovery relating to how that might have happened. The phenomenon of archea performing ingestion may well have remained confined to the vents if it was too energetically costly in the open ocean. Unless that archaea was carrying little mitochondrial powerhouses, in which case it was pretty well already eukaryotic. Far from equilibrium environments make for interesting developments.

Looks like you can develop eating only if you already have a free lunch!

Peter


Monday, May 18, 2015

Ketogenic Diet: Eat Food

From page 148 of the third edition (2000) of Freeman, Freeman and Kelly’s “The Ketogenic Diet”.

Daily intake for a 13 month old child:

Commercial formula providing 28.3 grams of fat composed of equal parts high oleic safflower oil, soy oil and coconut oil, plus an extra 38.1 grams of almost pure omega six from from a standard safflower oil emulsion, a little soy protein 'n' glucose polymer. Vitamins and minerals. A maximum of 980ml of water in total.

This paediatric ketogenic diet is a child of its time, steeped in the benefits of massive PUFA ingestion and often combined with phenobarbitone. The child in the case study above could barely swallow as a result of the high dose of phenobarbitone she was taking. If you were to suggest hepatopathy, dyslipdaemia and potentially fatal pancreatitis as sequelae of the diet, I would not be surprised.

Please do not feed this to your child, we are no longer in the 1970s.

On the other hand, if you order a steak in a restaurant and it comes to you with salad and chips on the side, you do not HAVE to eat the chips to stop yourself developing fulminating pancreatitis.

If you are post-obese, via low carb eating, there is every likelihood that repeatedly consuming the chips (to avoid the pancreatitis, don’tchano) will cure you of the post-ness of your obesity. Enjoy the chips by all means.

Peter

Sunday, March 29, 2015

HbA1c and Familial Hypercholesterolaemia

Ivor, over at thefatemperor, recently mentioned the lovely observational study, the Norfolk section of EPIC. That's where I live and it's HbA1c which correlates with CVD here. Cholesterol does not. At all. Tha' be 'ere in Norf'k, b'o'r. With apologies for the lapse in to the vernacular. My children are becoming experts. Computer is com-poo-er...

That nudged me to put this very brief observational post up on glucose dysregulation and CVD in the land where cholesterol is king, for people with heterozygous familial hypercholesterolaemia. There are many, many problems you could point out in this study, but those are intrinsic to a retrospective observational study. Take a group of hFH people who have survived a premature heart attack. Match a similar group of hFH people who haven't had a heart attack. How do you tell the difference between the groups? As a lipidologist perhaps you might suspect the LDL cholesterol level? That is exactly the problem in hFH after all... But:

"There was no difference in total and LDL cholesterol between the two groups. Patients with previous myocardial infarction had significantly higher levels of insulin, insulin resistance [and several other things I'm not interested in, which they would like to treat]..."

Insulin resistance is the problem, on a mixed diet. Do you think this might show in the HbA1c, just as it does here in Norfolk for us non hFH folks?

It probably does. In a similar observational study on hFH, using HbA1c itself rather than insulin/resistance parameters:

"Of special note is that HbA1c showed a significant correlation with average ATT [Achilles Tendon Thickness], independent of other parameters..."

Achilles Tendon Thickness is a marker of Badness in hFH. As your tendon thickens, so too does your carotid intima thicken.

In general, patients with hFH tend to have rather good glucose control compared to the general population. That might just be why they live as long as they do under the correct circumstances. But with hFH I suspect that, should you manage it, developing metabolic syndrome may be a very unforgiving problem. You have to wonder what side stepping the syndrome by low carb eating might do, giving chronic normoglycaemia without elevated post prandial insulin. Not holding my breath waiting for that one.

BTW, as statins worsen glycaemic control, could they actually make the CVD problems worse for hFH patients? Surely not. Surely we have stopped making booboos of this type. Of course we have. Of course.

Peter

Wednesday, March 25, 2015

Ketogenic vs moderate carbohydrate diets

I thought I might put up this graph:























It's from

Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women: The A TO Z Weight Loss Study: A Randomized Trial

The lead author does not appear to be a LCer. In general his publications are rather pro plants and quite mainstream. To his credit he has published some negative studies amongst the pro plant stuff. Harvard, ultimately, is no hotbed of pro Atkins zealotry.

If we want to look at the macros we can check here:

















A little arithmetic allows us to look at the carbohydrate intake on the first graph at differing time points for Atkins and Zone diets:

















Of course the Atkins diet was an unrestricted calories diet, Zone has a caloric restriction applied.

I have the impression from the data of the A-Z study that low carb is good, slightly higher carb is acceptable, adding more carbs back in is a booboo and that the Zone is crap. Just an impression. From the graph.

As an aside, of course the unanswered question is what, exactly, would a sustained 54g carb intake have produced in terms of weight loss over 12 months? Or 20g/d over 12m?

It is very clear that carbohydrate restriction only works WHEN YOU RESTRICT CARBOHYDRATE. A low carb diet does not appear to be as effective as a low carb diet when it has morphed in to an ex low carb diet through added carbs. A similar pattern might apply to ultra low fat diets if anyone wants to go down that dark alley. They don't work when you add fat. Assuming you don't mind the biochemistry while you eliminate fat.

It is also very clear that when comparing an almost-ketogenic diet to a modestly restricted carbohydrate diet of around 133g/d carbs, something like the Zone diet, the modest carbohydrate diet is just as good, if not a little better, than a ketogenic diet. You know the graph:























My problem is trying to square the circle between these two studies. Obviously, no study is free of bias. I struggle somewhat with Dr Sears, of the Zone diet, being the group leader of the study which shows a diet with 133g/d of carbohydrate out performs a ketogenic diet. That is very strange and doesn't happen in Stanford.

People must make up their own minds.

Peter

Sunday, March 15, 2015

Insulin detemir (3)

I think it is quite clear how I view insulin detemir. Kindke was unable to resist finding the link to the abstract with the diametrically opposing view. I'll just stick both links in here to keep them together, so people can look at both research findings and draw their own conclusions.

Insulin detemir is not transported across the blood-brain barrier.

versus

Insulin detemir is transported from blood to cerebrospinal fluid and has prolonged central anorectic action relative to NPH insulin.

I think it is reasonable to assume that at least one of these two papers is factually incorrect.

If you search on Begg and Woods as co-authors you will find papers redolent with words like "reward", "hedonic" and "dopamine".  That's Begg and Woods, if anyone can stomach it.

I was, in my normal confirmation biased way, much more interested in the sort of work produced by Banks, Morley and/or Mooradian. These folks appear to be scientists rather than psychiatrists and they have some great publications. They include major work on the blood brain barrier, leptin transport, insulin transport, leptin resistance, gerontology, diabetes, antioxidants, the list goes on and on.

Here are a few little gems I particularly enjoyed in abstract form which might be worth a mention.

I dislike antioxidants. This is quite interesting from Banks and Morley:

Effect of alpha-lipoic acid on memory, oxidation, and lifespan in SAMP8 mice.

Alpha lipoic acid is a mitochondrial component present in normal cells and is available in mega doses as a supplement. It's a serious and deeply mitochondrial penetrative antioxidant. It helps a lot with diabetic neuropathic pain. SAMP8 mice are oddities which have been bred for early onset senility and memory loss. They are used (probably totally inappropriately) for Alzheimers Disease research. Treating them with antioxidants improves their memory performance. You might think this is a good idea. The cost is measured by a shortening of their life as elderly SAMP8 mice from 34 weeks to 20 weeks after start of treatment (started at 11 months of age). This may or may not be a good thing if you are an SAMP8 mouse (death might be a release). How it applies to a person managing their diabetic neuropathy or trying to delay the progression of their Alzheimers Disease is fascinating and slightly worrisome. I'll stick to a life based around beta oxidation, normglycaemia and a little superoxide signalling, stuff the antioxidants. Last sentence of the abstract "These findings are similar to studies using other types of antioxidants". Sweet, provided you avoid sugar. And antioxidants.

The next snippet includes Morley and Mooradian as authors and relates to making your blood sweet,  literally this time, using intravenous glucose:

Mechanism of pain in diabetic peripheral neuropathy. Effect of glucose on pain perception in humans.

Simple hyperglycaemia in a normal person reduces the threshold for feeling pain. It reduces the severity of pain you can tolerate. This applies to a normal human being on a glucose infusion or a diabetic person on a diet designed by a diabetologist, no glucose infusion needed. If hyperglycaemia makes a tolerable stimulus in to a painful experience and makes just bearable pain become unbearable, how many chronic pain syndromes would go in to remission with sustained normoglycaemia? Fat phobia makes this question currently un-answerable. The paper was published in 1984. Does anyone fancy having a gangrenous foot amputated for diabetic complications and waking up on a dextrose saline infusion in recovery? And then being offered the "diabetes diet" on the post op ward?

Banks and Morley were also instrumental in the generation of data for the concept that trigycerides in plasma induce leptin resistance at the blood brain barrier, a few years old now but still quite a useful concept:

Triglycerides induce leptin resistance at the blood-brain barrier.

I find the cream bashing in this last paper a little distasteful and I have to admit that Banks appears to be unaware that high saturated fat low carbohydrate diets are THE way to reduce fasting trigycerides in real people. Can't have everything I suppose. But even if the cream effect applies to people, who cares if I am leptin resistant with a full stomach provided leptin will work perfectly well in the post absorptive (low triglyceride) period? I am a human, not a mouse. I ate a high fat meal without sugar last night, ergo I'm not hungry today. Low trigs equal leptin sensitivity...

I'll call a halt there. Life is full of interesting snippets which make sense. They usually come from the sort of people who say insulin detemir does not cross the blood brain barrier.

Peter

Wednesday, March 04, 2015

Insulin detemir (2)

Morphine is a rather odd opioid analgesic. It has a complex multi-ring structure with two rather prominent hydroxyl groups which render it rather more hydrophilic and significantly less lipid soluble than many of its relatives. If you bolus a patient with IV morphine there is a delay in its passage across the blood-brain barrier due to this relatively poor lipid solubility. Time to peak effect is significantly delayed to somewhere around 15 minutes because the brain concentration lags way behind the rapidly changing plasma concentration. The brain never "sees" the peak plasma concentration due to this delay.

Now, if you boil some morphine up with acetic acid you can form ester linkages joining acetate on to those two hydroxyl radicals to give you di-acetyl morphine, better known as diamorphine or heroin. Masking the hydroxyl radicals markedly increases the lipid solubility of the drug and so the brain concentration rapidly follows the plasma concentration. In general lipid soluble agents cross the blood brain barrier rather faster than more water soluble agents. Peak plasma concentration will give a rapid onset peak brain concentration, which appears to be associated with effects rarely seen with morphine itself. Giving the enhanced recreational potential. This is all basic anaesthesia pharmacology with excerpts from Trainspotting thrown in.

Insulin detemir was developed to give an insulin with a very flat glycaemia controlling effect for use as a basal or background insulin. The clever people at Novo Nordisk deleted the terminal threonine from the B chain and attached a medium chain fatty acid to the now terminal lysine at position B29. The rather nice 14 carbon saturated fat, myristic acid, sticks out from the insulin molecule and neatly binds to the fatty acid binding site of albumin. It does this very rapidly and keeps the insulin bound and ineffective. Over the hours which follow there is a slow dissociation of the insulin from albumin which allows a very shallow dose response rate for glucose control. Ideal for a basal insulin.

There is a suggestion that this tagging of insulin might facilitate its transport in to the brain, a sort of heroin-insulin tweak. The idea is that myristic acid might facilitate the transport of insulin in to the brain and lead to a massive suppression of eating and subsequent weight loss. Assuming you are a true believer in the central anorectic effect of insulin. Which, sadly, I'm not.

Years ago, when insulin determir was first paraded as the living proof of the central anorectic effect of insulin, I looked up its structure and thought, as you do, that FFAs in general have very limited access to the brain. Insulin is not morphine and the myristic acid is not acetic acid. That big, long side chain of detemir is directly related to the sorts of free fatty acids which are specifically excluded from the brain. My own prediction would be that insulin detemir would have a significantly REDUCED effect within the brain.

It turns out that, at least in some labs, that my idea was slightly correct. But my idea was limited compared to the actual effect. Insulin detemir not only fails to cross the blood brain barrier itself but it also blocks the ability of ordinary human insulin to pass from plasma in to the brain. There is probably a specific insulin transporter which is nicely blockaded by an insulin molecule with the fatty acid tail of detemir sticking out. This paper says it all:

Insulin Detemir is Not Transported Across the Blood-Brain Barrier

Not a lot of mincing of words there.

If we go to labs with an outlook on life which I find comprehensible we can clearly see that physiological doses of insulin, within the brain, augment lipid uptake in to adipocytes, enhance adipocyte sensitivity to insulin, increase lipogenesis and augment fat gain. Largely through the sympathetic nervous system. I can't see how anyone would be surprised by this. Quite why anyone would expect central insulin to do the opposite of what peripheral insulin does at a comparable concentration is beyond me. I enjoyed this paper:

Central insulin action regulates peripheral glucose and fat metabolism in mice

"Moreover, chronic intracerebroventricular insulin treatment of control mice increased fat mass, fat cell size, and adipose tissue lipoprotein lipase expression, indicating that CNS insulin action promotes lipogenesis. These studies demonstrate that central insulin action plays an important role in regulating WAT mass and glucose metabolism via hepatic Stat3 activation".

How clearly does it need to be spelled out? This one is fun too:

Brain insulin controls adipose tissue lipolysis and lipogenesis.

"Here, we show that insulin infused into the mediobasal hypothalamus (MBH) of Sprague-Dawley rats increases WAT lipogenic protein expression, inactivates hormone-sensitive lipase (Hsl), and suppresses lipolysis. Conversely, mice that lack the neuronal insulin receptor exhibit unrestrained lipolysis and decreased de novo lipogenesis in WAT".


If you go looking you can find papers from Oz and Cincinatti which show that insulin detemir DOES cross the blood brain barrier and DOES suppress food intake, far better than neutral insulin does. In their own labs of course.

But I cannot forget that if you transport a researcher out of a Cincinatti psychiatry department and put her in to an industrial insulin lab she cannot get any effect of centrally infused insulin detemir or neutral insulin for that matter. Novo Nordisk cannot demonstrate this marvellous effect of insulin, even their own special insulin, in their own lab. We all know that much of the mindset of obesity research is not particularly effective at producing results which work. How they get the results derived from their ideas in their labs is what fascinates me! You couldn't make stuff up this counter intuitive. Maybe in another post.

Back in the real world we have this:

Insulin detemir results in less weight gain than NPH insulin when used in basal-bolus therapy for type 2 diabetes mellitus, and this advantage increases with baseline body mass index

Insulin detemir causes a small weight loss in morbidly obese patients, those with BMI >35kg/m2. Why? Because it blocks the brain entry of the chronically (and markedly) elevated levels of insulin so common in the morbidly obese. It has limited or zero effect within the brain in its own right. The brain simply loses awareness of the systemic pathologically elevated insulin. If plasma insulin is high enough this sudden loss of insulin's access to the brain can result in a decrease in brain driven, neurologically mediated, forced lipid storage in adipocytes, i.e. a little weight loss.

In the absence of marked hyperinsulinamia, i.e. in less obese type 2 diabetics, insulin detemir causes weight gain because there is less tonically elevated plasma insulin for the central uptake blockade to neutralise. There is no weight loss effect, although gain is undoubtedly blunted.

Insulin detemir is the best indicator I have seen that the central role of physiological concentrations of insulin within the brain is to augment fat storage. This makes sense to me.

I wouldn't ask a psychiatrist to develop an anaesthetic protocol. Or a weight loss protocol!

Peter