Evolution, Nephrology, hemodynamics, ED. etc.
. Author has
the wrong there for CVD, blaming it on salt, fat, and meat, which the other
primates don’t get, and uses the Maori and Aborigines of Australia as examples
of those with gout, while missing fructose.
http://europepmc.org/abstract/med/15660328
Uric acid,
evolution
and primitive cultures
Hypertension is epidemic and currently affects 25% of
the
world’s population and is a major cause of stroke, congestive heart failure,
and end-stage renal disease. Interestingly, there is evidence that the
increased frequency of hypertension is a recent event in human history and
correlates with dietary changes associated with Westernization.[1]
In this article, we review the evidence that links uric acid to the cause and
epidemiology of hypertension. Specifically, we review the evidence that the
mutation of uricase that
occurred in the Miocene that resulted in a higher serum uric acid in humans
compared with most other mammals may have occurred as a means to increase blood
pressure in early hominoids in response to a low-sodium and low-purine diet. [Suspect because higher blood pressure
doesn’t have a survival value, though increased antioxidant function of uric
acid dose. Secondly there is a balance
act between harm caused by uric acid and benefit. The atherogenic role of the
high fructose
western diet is what has raised BP.] We
then review the evidence that the epidemic of hypertension that evolved with
Westernization was associated with an increase in the intake of red meat with a
marked increase in serum uric acid levels. Indeed, gout and hyperuricemia
should be considered a part of the obesity, type 2 diabetes, and hypertension
epidemic that is occurring worldwide. Although other mechanisms certainly
contribute to the pathogenesis of hypertension, the possibility that serum uric
acid level may have a major role is suggested by these studies.
FROM FULL PDF https://s3.amazonaws.com/academia.edu.documents/46082733/Uric_acid_evolution_and_primitive_cultur20160530-19206-vh4w49.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1515438682&Signature=ozw8c2iZMzlYdKHQ0SACGy89ehY%3D&response-content-disposition=inline%3B%20filename%3DUric_acid_evolution_and_primitive_cultur.pdf
Serum uric acid levels are
therefore low (0.5– 2.0 mg/dL) in most mammals. However, during the Miocene
epoch (8 –20 million years ago) parallel mutations occurred in our hominoid
ancestors that first affected the promoter region and later the whole gene,
eventually resulting in complete loss of uricase.6 As a consequence, humans and
the Great Apes have higher uric acid levels than most other mammals. In
addition, some species of New World monkeys also lost uricase, and many Old
World monkeys have lower uricase activity than other mammals,7 suggesting
similar processes in these species. The stepwise loss of uricase may have
allowed adaptation to the loss of this important gene because the sudden
knockout of uricase in mice is lethal owing to dramatic increases in serum uric
acid levels that cause acute urate nephropathy and renal failure.8 One likely
adaptation was a decrease in xanthine oxidase activity because humans have only
1% activity of this enzyme compared with other mammals.9 It also is possible
that alterations in transport mechanisms involved in renal urate excretion may
have occurred.
2 A similar antioxidant hypothesis
suggests that the uricase mutation occurred as a consequence of the loss of our
ability to synthesize vitamin C.13 Our ability to synthesize vitamin C was lost
approximately 40 to 50 million years ago owing to a mutation in
L-gulono-lactone oxidase.14 This mutation may have occurred because the
primates of that period were largely fruit eating and hence were ingesting
large quantities of vitamin C, making the mutation harmless.15 However, later
there was a selection advantage for those species that could increase their
antioxidants, and this was provided by the uricase mutation….
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Uric acid and chronic renal disease: Possible implication of
hyperuricemia on progression of renal disease
Abstract
Although
hyperuricemia has long
been associated with renal disease, uric acid has not been considered as a true
mediator of progression of renal disease. The observation that hyperuricemia
commonly is associated with other risk factors of cardiovascular and renal
disease, especially hypertension, has made it difficult to dissect the effect
of uric acid itself. However, recent epidemiologic evidence suggests a
significant and independent association between the level of serum uric acid
and renal disease progression with beneficial effect of decreasing uric acid
levels. Furthermore, our experimental data using hyperuricemic animals and
cultured cells have provided robust evidence regarding the role of uric acid on
progression of renal disease. Hyperuricemia increased systemic blood pressure, proteinuria,
renal dysfunction, vascular disease, and progressive renal scarring in rats. Recent data also suggest hyperuricemia may be one of the key and
previously unknown mechanisms for the activation of the renin-angiotensin and
cyclooxygenase-2 (COX-2) systems in progressive renal disease. Although we must
be cautious in the interpretation of animal models to human disease, these
studies provide a mechanism to explain epidemiologic data that show uric acid
is an independent risk factor for renal progression. Although there is no
concrete evidence yet that uric acid bears a causal or reversible relationship
to progressive renal disease in humans, it is time to reevaluate the
implication of hyperuricemia as an important player for progression of renal
disease and to try to find safe and reasonable therapeutic modalities in
individual patients based on their clinical data, medication history, and the
presence of cardiovascular complications.
From full PDF Seminar in Nephrology 2005, Supra.
43-49
Increased production of uric acid is the result of interference,
by a
product of fructose metabolism, in purine metabolism.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
http://www.sciencedirect.com/science/article/pii/S0270929504001470
Pages 19-24, supra.
Seminars in Nephrology, Jan. 2005
Hemodynamics
of hyperuricemia
Prolonged hyperuricemia is
associated with the development of hypertension, renal arteriolosclerosis,
glomerulosclerosis, and tubulointerstitial injury. It confers a greater risk than proteinuria for developing
chronic renal disease and is associated with the development of hypertension.
Mild chronic hyperuricemia without intrarenal crystal deposition was induced in
rats by inhibiting uricase with oxonic acid. Hyperuricemic rats developed
hypertension, afferent arteriolar thickening, and mild renal interstitial
fibrosis. Additionally, hyperuricemia accelerated renal damage and vascular
disease in rats undergoing renal ablation. To better understand the role of
hyperuricemia in the kidney, micropuncture studies were performed.
Hyperuricemia resulted in renal cortical vasoconstriction (single nephron
glomerular filtration rate (SNGFR) ↓ 35%, P <
.05) and glomerular hypertension
(P <
.05). The possibility that hyperuricemia could modify renal hemodynamic
disturbances during progression of renal disease was tested in rats with 5/6
nephrectomy. Hyperuricemia accentuated the renal vascular damage and caused
cortical vasoconstriction (SNGFR ↓ 40%, P <
.05) and persistent glomerular hypertension. In conclusion, hyperuricemia
impairs the autoregulatory response of preglomerular vessels, resulting in
glomerular hypertension. Lumen obliteration induced by vascular wall thickening
results in severe vasoconstriction. The
resulting ischemia is a potent stimulus that induces tubulointerstitial
inflammation and fibrosis as well as arterial hypertension.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
http://www.sciencedirect.com/science/article/pii/S0270929504001500 Supra. 39-42
Uric
acid as a mediator of endothelial dysfunction, inflammation, and vascular
disease
Recent experimental findings have led to renewed interest in the
possible role of uric acid in the pathogenesis of both hypertension and
vascular disease. Often considered an antioxidant,
biochemical and in vitro data indicate that noncrystalline, soluble uric acid
also can react to form radicals, increase lipid oxidation, and induce various
pro-oxidant effects in vascular cells. In vitro and in vivo findings suggest
that uric acid may contribute to endothelial dysfunction by inducing antiproliferative
effects on endothelium and impairing nitric oxide production. Proinflammatory
and proliferative effects of soluble uric acid have been described on vascular
smooth muscle cells (VSMCs), and
in animal models of mild hyperuricemia, hypertension develops in association with intrarenal
vascular disease. Possible
adverse effects of uric acid on the vasculature have
been linked to increased chemokine and cytokine expression, induction of the
renin-angiotensin system, and to increased vascular C-reactive protein (CRP)
expression. Experimental evidence suggests a complex but potentially direct
causal role for uric acid in the pathogenesis of hypertension and
atherosclerosis.
[1] The 1956 Merck Manual places the US rate at
5%. A large part of the difference
is that of the defining blood pressure
has been significantly lowered to 140
distolic; however, the world figures include those not on a western diet, for
whom hypertension is virtually unknown; thus more than offsetting the increase
by defining pressure.
The next article argues that too much attention has been
given
to hyperuricemia while ignoring the role of uric acid. “Although
hyperuricemia has long been associated with renal disease, uric acid has not
been considered as a true mediator of progression of renal disease…. data that
show uric acid is an independent risk factor for renal progression.” An
issue exists in that “hyperuricemia” is
measured as urate, rather than uric acid crystals.
Labeled as an organic acid, Uric acid: “On the structure shown at the upper-right, the NH at the
upper-right on
the six-membered ring is "1…. while
most organic acids are deprotonated by the ionization of a polar
hydrogen–oxygen bond, usually accompanied by some form of resonance
stabilization (resulting in a carboxylate ion), uric acid is deprotonated at a nitrogen atom… The
five-membered ring also possesses a keto group (in the 8 position), flanked by
two secondary amino groups (in the 7 and 9 positions)… lacks a hydrogen either
on nitrogen 9 or on nitrogen 3,” https://en.wikipedia.org/wiki/Uric_acid Its Ph
is 5.4, and its PK is 10.3, at
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Wiki articles ignores fructose and blames IR, HBP, hypothyroidism,
hyperthyroidism, renal insufficiency, obesity, diet, use of diuretics
(thiazides & loop diuretics), and most important excess alcohol
consumption. “A purine-rich diet is a common but minor cause
of hyperuricemia. Diet alone generally is not sufficient to cause
hyperuricemia.” https://en.wikipedia.org/wiki/Hyperuricemia
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