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B Marescau

Publications and source records attributed to B Marescau.

At least 19 recordsLinked to original sources
PubMed2006

Biochemical validation of a rat model for polycystic kidney disease: comparison of guanidino compound profile with the human condition.

Polycystic kidney disease (PKD) accounts for 7-10% of all dialyzed renal insufficient patients. Accumulation of specific guanidino compounds (GCs) has been related to neurological, cardiovascular, hematological, and immunological complications of renal failure. In this study, we investigate whether the PKD/Mhm rat model can be used as a biochemical model for human PKD. For the validation of the rat model, we performed the first detailed evaluation of the concentrations of GCs in serum and urine of patients with PKD in addition to the GC patterns in the plasma, urine, and tissues of the PKD/Mhm rat model. The GCs were determined after separation on a cation exchange resin and fluorescence detection. The GC levels and changes observed in blood and urine of patients with PKD are comparable with those found in patients with renal insufficiency due to different etiologies. The PKD/Mhm rat model can be used as a biochemical model for human PKD as the obvious increases of urea, guanidinosuccinic acid, creatinine, guanidine, methylguanidine, and N(G)N(G)-dimethylarginine (symmetrical dimethylarginine) seen in blood of oldest heterozygous and younger homozygous PKD rats were largely within the same range as those found in the studied human PKD population, especially in patients with a glomerular filtration rate below 60 ml/min/1.73 m(2). The decreased levels of plasma guanidinoacetic acid seen at end-stage renal disease in homozygous and oldest heterozygous rats were also observed in serum of patients with a glomerular filtration rate below 20 ml/min/1.73 m(2). The PKD/Mhm rat model has, besides similar disease characteristics with human PKD, comparable GC alterations.

Animals↗
PubMed2005

Regional distribution of biogenic amines, amino acids and cholinergic markers in the CNS of the C57BL/6 strain.

A reliable extrapolation of neurochemical alterations from a mouse model to human metabolic brain disease requires knowledge of neurotransmitter levels and related compounds in control mouse brain. C57BL/6 is a widely used background strain for knockout and transgenic mouse models. A prerequisite for reliable extrapolation from mouse brain to the human condition is the existence of analogous distribution patterns of neurotransmitters and related compounds in control mouse and human brain. We analysed regional distribution patterns of biogenic amines, neurotransmitter and non-neurotransmitter amino acids, and cholinergic markers. Distribution patterns were compared with known neurotransmitter pathways in human brain. The present study provides a reference work for future analyses of neurotransmitters and related compounds in mouse models bred in a C57BL/6 background strain.

Amino Acids↗
PubMed2004

Effect of NaCN on currents evoked by uremic retention solutes in dissociated mouse neurons.

Uremic retention solutes possibly contribute to neuronal hypoxia/ischemia and its consequences in patients with renal failure. We examined the in vitro effects of several uremic retention solutes on murine central neurons under chemically induced metabolic hypoxia by application of sodium cyanide (NaCN). Whole cell currents were recorded using the tight-seal whole-cell voltage clamp technique. Application of NaCN caused an inward whole-cell current. From all tested toxins, which included several indoles, guanidino compounds, polyamines, purines, phenols, DL-homocysteine, orotate and myoinositol, only creatinine (CTN), guanidine (G) and guanidinosuccinic acid (GSA) produced a significant current in control and hypoxic neurons. Current evoked by GSA was significantly increased in the chemical hypoxic condition, and a synergistic effect of GSA and spermine was observed in hypoxic neurons.

Animals↗
PubMed2003

The low nanomolar levels of N G-monomethylarginine in serum and urine of patients with chronic renal insufficiency are not significantly different from control levels.

There are no reliable mean values of N(G)-monomethylarginine (NMMA) in blood and urine of patients with renal insufficiency available in the literature. Therefore we investigate whether the NMMA levels are changed in blood and urinary excretion of nondialysed and dialysed patients with chronic renal insufficiency to evaluate whether NMMA may reach sufficiently increased concentrations in blood of the patients to exert toxic biological activity. In nondialysed as well as in dialysed patients we find no significant difference in serum concentration of NMMA between patients and controls. In nondialysed patients (all with a residual creatinine clearance lower than 15 ml/min), we find 94.5 +/- 26.1 nM (mean +/- SD) versus 94.6 +/- 19.5 nM in controls. Similar levels are found in serum of haemodialysed patients (each with serum creatinine levels >700 micro M): 83.0 +/- 20.2 nM. The urinary excretion of NMMA in nondialysed patients is also not significantly different from the excretion of controls: 123 +/- 110 in patients versus 157 +/- 117 nmol/24 hrs in controls. Furthermore, the clearance of NMMA is much lower compared to the clearance of the dimethylarginine derivatives. Based on the literature, the low nanomolar levels of NMMA found in blood of patients with renal insufficiency do not support the statement that NMMA proper may act as a uremic toxin.

Adult↗
PubMed2003

Amino acids and biogenic amines in cerebrospinal fluid of patients with Parkinson's disease.

To study changes in amino acid metabolism and biogenic amines in Parkinson's disease, we set up a prospective study and measured biogenic amines, their main metabolites, and 22 different amino acids, in cerebrospinal fluid of Parkinson's disease patients (n = 24) and age-matched controls (n = 30). A trend toward higher dopamine levels in Parkinson's disease patients was interpreted as an effect of treatment with levodopa and/or selegiline. Significantly lower concentrations of the dopamine metabolite 3,4-dihydroxyphenylacetic acid in the Parkinson's disease group might reflect dopaminergic cell loss. Our results revealed decreased serotonin catabolism that was interpreted as an effect of treatment with selegiline. Whereas all amino acid levels were unchanged, taurine was significantly lower in Parkinson's disease patients. Studies showed that taurine exerts a trophic action on the central nervous system. In this view, decreased taurine in a neurodegenerative disorder as Parkinson's disease deserves attention.

Aged↗
PubMed2001

Influence of 72% injury in one kidney on several organs involved in guanidino compound metabolism: a time course study.

Arginine (Arg) produced from citrulline originates mostly from kidneys. Arg is involved in guanidino compound biosynthesis, which requires interorgan co-operation. In renal insufficiency, citrulline accumulates in the plasma in proportion to renal damage. Thus, disturbances in Arg and guanidino compound metabolism are expected in several tissues. An original use of the model of nephrectomy based on ligating branches of the renal artery allowed us to investigate Arg and guanidino compound metabolism simultaneously in injured (left) and healthy (right) kidneys. The left kidney of adult rats was subjected to 72% nephrectomy. Non-operated, sham-operated and nephrectomized rats were studied for a period of 21 days. Constant renal growth was observed only in the healthy kidneys. Guanidino compound levels were modified transiently during the first 48 h. The metabolism and/or tissue content of several guanidino compounds were disturbed throughout the experimental period. Arg synthesis was greatly reduced in the injured kidney, while it increased in the healthy kidney. The renal production of guanidinoacetic acid decreased in the injured kidney and its urinary excretion was reduced. The experimentally proven toxins alpha-keto-delta-guanidinovaleric acid and guanidinosuccinic acid (GSA) accumulated only in the injured kidney. The urinary excretion of GSA and methylguanidine increased in nephrectomized rats. When the injured kidney grew again, the level of some guanidino compounds tended to normalize. Nephrectomy affected the guanidino compound levels and metabolism in muscles and liver. In conclusion, the specific accumulation of toxic guanidino compounds in the injured kidney reflects disturbances in renal metabolism and function. The healthy kidney compensates for the injured kidney's loss of metabolic functions (e.g. Arg: production). This model is excellent for investigating renal metabolism when a disease destroys a limited area in one kidney, as is observed in patients.

Acute Kidney Injury↗
PubMed2001

The effect of high protein diet on urea and guanidino compound levels in renal insufficient mice.

Nephrectomy in mice provokes a decrease in creatinine clearance (CTN(Cl)) and an increase in urea and specific guanidino compound (GC) concentrations in blood and other tissues. Our purpose was to investigate the influence of high protein diet (HPD) on CTN(Cl), urea and GC levels in NX mice. Mice were nephrectomized or sham-operated and subdivided in groups to study five diet conditions. At the end of each experiment, 10 days and 30 days postsurgery, urine and blood were collected for determination of urea and GCs, including creatinine. HPD resulted in significantly higher CTN(Cl) values in sham-operated mice than those observed in mice under normal protein diet, 10 days as well as 30 days postnephrectomy. HPD induced significant increases in plasma urea, guanidinosuccinic acid, argininic acid and a-keto-delta-guanidinovaleric acid concentration 10 days postsurgery but not 30 days postsurgery. HPD coincided with significantly higher excretion of urea, guanidinosuccinic acid, alpha-keto-delta-guanidinovaleric acid, creatine, argininic acid and gamma-guanidinobutyric acid in sham-operated and nephrectomized mice 10 days postsurgery. Our results show that HPD induces supplementary (to nephrectomy) increases of urea and GCs in the early postsurgery period but not in the later phase.

Animals↗
PubMed2001

Endogenous guanidino compounds as uremic neurotoxins.

Epileptic and cognitive symptomatologies are among the most typical manifestations of uremic encephalopathy. Several guanidino compounds (GCs) may play an important role in the etiology of uremic encephalopathy. Four GCs appeared to be highly increased as well in serum, cerebrospinal fluid, and brain of uremic patients, whereas the levels of other metabolically relevant GCs were not or only moderately increased and others were even decreased. These highly increased compounds or "uremic" GCs are creatinine (CTN), guanidine (G), guanidinosuccinic acid (GSA), and methylguanidine (MG). All four compounds were shown to be experimental convulsants in brain concentrations similar to those found in uremic brain. We have described a possible mechanism for the contribution of GCs to uremic hyperexcitability, referring to the in vitro effects of uremic GCs on inhibitory and excitatory amino acid receptors. The excitatory effects of uremic GCs on the central nervous system may be explained by the activation of N-methyl-D-aspartate (NMDA) receptors by GSA, concomitant inhibition of GABA(A) receptors by uremic GCs, and other depolarizing effects. These effects might also indicate the putative contribution of uremic GCs to the etiology of uremic encephalopathy.

Animals↗
PubMed2001

Long-term effect of partial nephrectomy on biological parameters, kidney histology, and guanidino compound levels in mice.

The long-term adverse consequences of early renal mass reduction in mice have not yet been investigated. The effects of partial surgical nephrectomy (NX) in 2-month-old mice on some biological parameters, on histopathologic and morphometric features of the kidney, and on urea and guanidino compound (GC) levels in plasma, urine, and brain were examined at 10 days, and 1, 2, 4, and 12 months postsurgery. Body weight, urinary volume, and plasma urea were most affected at 10 days and 12 months post-NX. NX-induced changes in the remaining renal tissue (including hypertrophy, glomerular mesangial expansion, and presence of protein casts) increased with age. As in human renal insufficiency, NX mice showed significantly higher plasma guanidinosuccinic acid (GSA) and creatinine (CTN) levels at all studied periods. The same tendency could be seen for most other plasma GCs examined, except for arginine (Arg), guanidinoacetic acid (GAA), and homoarginine (HA). As seen in human pathobiochemistry, the latter 2 compounds tended to be lower in NX mice in our follow-up study. Remarkably, and also similar to humans, NX mice excreted less GAA and more GSA than controls during the entire follow-up study. During the follow-up, excretion levels of GAA were unchanged in NX and sham-operated mice. In brain, GAA and gamma-guanidinobutyric acid (GBA) levels were always higher in NX mice with a tendency to respectively increase or decrease over time in NX as well as sham-operated mice. Although urea and GC metabolism were influenced by time post-NX and aging, the model was confirmed to display a mild stable chronic impairment of renal function. Histopathologic and morphometric changes of the kidney increased with age.

Aging↗
PubMed2001

Overexpression of arginase alters circulating and tissue amino acids and guanidino compounds and affects neuromotor behavior in mice.

Arginine is an intermediate of the ornithine cycle and serves as a precursor for the synthesis of nitric oxide, creatine, agmatine and proteins. It is considered to be a conditionally essential amino acid because endogenous synthesis only barely meets daily requirements. In rapidly growing suckling neonates, endogenous arginine biosynthesis is crucial to compensate for the insufficient supply of arginine via the milk. Evidence is accumulating that the intestine rather than the kidney plays a major role in arginine synthesis in this period. Accordingly, ectopic expression of hepatic arginase in murine enterocytes by genetic modification induces a selective arginine deficiency. The ensuing phenotype, whose severity correlates with the level of transgene expression in the enterocytes, could be reversed with arginine supplementation. We analyzed the effect of arginine deficiency on guanidine metabolism and neuromotor behavior. Arginine-deficient transgenic mice continued to suffer from an arginine deficiency after the arginine biosynthetic enzymes had disappeared from the enterocytes. Postweaning catch-up growth in arginine-deficient mice was characterized by increased levels of all measured amino acids except arginine. Furthermore, plasma total amino acid concentration, including arginine, was significantly lower in adult male than in adult female transgenic mice. Decreases in the concentration of plasma and tissue arginine led to significant decreases in most metabolites of arginine. However, the accumulation of the toxic guanidino compounds, guanidinosuccinic acid and methylguanidine, corresponded inversely with circulating arginine concentration, possibly reflecting a higher oxidative stress under hypoargininemic conditions. In addition, hypoargininemia was associated with disturbed neuromotor behavior, although brain levels of toxic guanidino compounds and ammonia were normal.

Amino Acids↗
PubMed2001

Biochemical, histological and behavioral consequences of nephrectomy in young and aged mice.

BACKGROUND: This study investigates the effect of nephrectomy in young and aged mice on some biochemical, histological and behavioural aspects. METHODS: Each age group, 2- and 12-months-old, comprised a sham-operated group, a unilaterally nephrectomized group and a subtotally nephrectomized group. Consequences of nephrectomy were examined 10 days postsurgery on urea and guanidino compound levels in body fluids and brain; the remaining kidney by light-microscopic examination; and learning and memory abilities using the Morris water maze task. RESULTS: Effect of nephrectomy on urea and guanidino compound levels in plasma, urine and brain was significantly more pronounced in the young age group. Some guanidino compounds show a tendency to decrease with aging in the sham-operated group and the two nephrectomized groups. Higher compensatory kidney hypertrophy was found in younger nephrectomized mice whereas in older mice glomerular mesangial expansion was a common feature. Finally, young mice with subtotal nephrectomy displayed a slight but significant impairment in memory and learning; whilst old nephrectomized mice manifested no impairment. CONCLUSIONS: Nephrectomy induces more changes in younger mice than in older mice as observed in higher variation of urea and guanidino compound levels, glomerular volume and kidney hypertrophy and decline in spatial learning and memory.

Age Factors↗
PubMed2000

Impaired cognitive performance in ornithine transcarbamylase-deficient mice on arginine-free diet.

Sparse-fur (spf) mice are a model for the congenital deficiency of ornithine transcarbamylase (OTC), the most common inborn error of urea synthesis in man. In this study, performance of clinically stable spf and control mice (8-10-weeks-old) on two learning tests was assessed under normal Arg(+) or arginine-free Arg(-) diet conditions. Used as an indicator of the metabolic status of the animals, plasma ammonia concentrations were significantly higher in spf than in controls on normal diet, and increased even more during the Arg(-) diet episode. Behaviourally, we found no difference in passive avoidance learning between control and spf mice on Arg(+) diet, whereas in spf mice receiving Arg(-) diet during training, retention performance was significantly reduced. In the hidden-platform water maze, spf mice on Arg(+) diet only showed decreased swimming velocity compared to controls. In mice on Arg(-) diet during the first week of acquisition training, performance on acquisition and retention (probe) trials showed that spf mice experienced more difficulties in actually locating the platform. Visible-platform control experiments only showed a reduction in swimming velocity in spf mice on either diet. We conclude that cognitive performance is impaired in spf mice as a consequence of Arg(-) diet-induced neurochemical alterations.

Ammonia↗
PubMed2000

NG, NG-dimethylarginine and NG, NG-dimethylarginine in renal insufficiency.

Asymmetric NG,NG-dimethylarginine (ADMA) and symmetric NG,NG-dimethylarginine (SDMA) are basic endogenous amino acids with a guanidino group. Our renal distribution study of dimethylarginines clearly indicates that, in mouse and rat, ADMA and SDMA levels are most abundant as protein-incorporated compounds (95%). ADMA represents almost 90% of this protein-incorporated dimethylarginine amount. The four zones studied (cortex, outer and inner stripe of outer medulla, inner medulla) contain more or less the same amount of protein-incorporated dimethylarginine; the concentrations of both free dimethylarginines vary more in the different zones. Plasma and urinary excretion levels in Man, rat and mouse were determined, their changes in renal insufficiency were examined and compared between species. Highly significant negative correlations between both plasma dimethylarginine levels and creatinine clearances were found in Man and rat. The correlation between urinary ADMA excretion levels and creatinine clearances was highly significant and positive in Man and mouse; however, in rat the correlation was negative. In patients with severe renal insufficiency, ADMA clearance was only 9.5% of controls, and that of SDMA only 7.8%. Clearance of ADMA and SDMA in nephrectomized mice was 60.5% and 53.8% of controls, respectively, whereas in nephrectomized rat, ADMA clearance actually increased 5.4 times and that of SDMA did not change significantly. Man, rat and mouse show similarities as well as differences in metabolism.

Aged↗
PubMed2000

Consequences of renal mass reduction on amino acid and biogenic amine levels in nephrectomized mice.

Amino acid and biogenic amine changes were investigated in nephrectomized mice ten days postsurgery. Uremic mice exhibited changes in amino acid concentrations in plasma, urine and brain. Particularly plasma methionine, citrulline and arginine levels were significantly enhanced in nephrectomized mice compared to controls whereas serine was decreased. Urinary excretion of methionine, citrulline and alanine was higher in nephrectomized mice compared to controls whereas many amino acids were increased in brain of nephrectomized mice. Brain and urinary amino acid changes were more pronounced in the 75% than in the 50% nephrectomized mice. Brain norepinephrine and dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid were significantly increased whereas serotonin was decreased comparing the 75% nephrectomized mice to the sham-operated mice. This study demonstrates that at very early stages of renal insufficiency, specific amino acid and biogenic amine changes occur in plasma, urine and brain. These alterations might depend qualitatively and quantitatively on the degree of functional renal mass reduction.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Behavioural deficits during the acute phase of mild renal failure in mice.

Partially nephrectomized (NX) and sham-operated mice were biochemically and behaviourally compared, 10 days, 1 month and 1 year post-surgery. Plasma urea and creatinine concentrations were mildly increased in all NX groups, but creatinine clearance was significantly decreased, 10 days post-surgery only. NX mice showed lower body weights and reduced growth. Wire suspension and rotarod indicated unaffected motor functions, but NX mice did show reduced ambulation and swimming velocity, 10 days post-surgery. Hidden-platform water maze indicated a spatial learning impairment in NX mice, 10 days post-surgery, which could not be entirely reduced to motor incapacity. The acute behavioural deficits in these mildly uremic mice may relate to analogous symptoms in uraemic encephalopathy, a poorly understood brain syndrome occurring in uraemic patients.

Acute Kidney Injury↗
PubMed1998

Biochemical and histopathological changes in nephrectomized mice.

Renal failure is characterized by the retention of nitrogenous metabolites such as urea, creatinine (CTN) and other guanidino compounds (GCs), uric acid, and hippuric acid, which could be related to the clinical syndrome associated with renal insufficiency. A model of renal failure has been developed in male C57BL x Swiss-Webster mice using nephrectomy (NX) and/or arterial ligation. A sham group (group A) and two nephrectomized groups, group B (one kidney removed) and group C (one kidney removed and ligation of the contralateral anterior artery branch), were studied. Ten days postsurgery, morphological and functional indices of renal failure were investigated. Nephrectomized mice manifested features of renal failure like polyuria and wasting. CTN clearance (CTN[Cl]) decreased by +/-26% in group B and +/-33% in group C as compared with the control values. Marked increases in the plasma concentration of guanidinosuccinic acid ([GSA] fourfold) and guanidine ([G] twofold) were observed in the experimental animals. CTN and alpha-keto-delta-guanidinovaleric acid (alpha-keto-delta-GVA) reached levels of, respectively, 1.5-fold and twofold those of controls. Urinary GSA excretion increased and guanidinoacetic acid (GAA) excretion decreased about twofold in group C. GSA increases (2.6-fold) were also observed in the brain in group C, in addition to a significant increase of G (2.5-fold) and gamma-guanidinobutyric acid ([GBA] 1.5-fold). Finally, the extent of NX was found to be 45.2% in group B and 71.4% in group C. Light microscopy revealed an expansion and increase in cellularity of the mesangium of the glomeruli, particularly in group C. A significant correlation (r = .574, P < .0001) was found between CTN(Cl) and the degree of NX as calculated from the remaining functional area. These data suggest that the model can be used as a tool for further pathophysiological and/or behavioral investigations of renal failure.

Animals↗