Search PubMed⌕ Search

Biomedical subjects

P Cartier

Publications and source records attributed to P Cartier.

At least 91 records · Page 5Linked to original sources
PubMed1976

[Adenosine deaminase activity in human erythrocytes and lymphocytes].

A radiochromatographic method is described for measuring enzymatic activity of adenosine deaminase in human erythrocytes and lymphocytes. [8-14C]-adenosine is converted into inosine and hypoxanthine; after chromatographic separation of the products, the radioactivity is determined. The kinetic properties of the enzyme have been studied. The Km values for the erythrocyte and lymphocyte enzymes are higher as compared with purified deaminase. Optimum conditions for substrate concentration for assay were established. The mean normal activity (+/- S.E. of mean) is: for erythrocytes, 494 +/- 61; nmol min-1 ml-1; for lymphocytes- 147 +/- 0.18 nmol min-1 10(6) cellules. The mean values are higher than that given by other methods working at a lower (non-staurating) substrate concentration.

Adenosine Deaminase↗
PubMed1976

Effect of fatty acids on renal ammoniagenesis in in vivo and in vitro studies.

Intravenous or renal intra-arterial infusion of sodium octanoate results in a 60% decrease in renal ammoniagenesis in the acidotic dog. Mobilization of endogenous fatty acids by levarterenol infusion is accompanied by a 30% fall in renal ammoniagenesis which coincides with considerable increase in renal extraction of fatty acids. In both types of experiments, the renal extraction of glutamine falls in proportion with decreased ammoniagenesis. The effect of octanoate and levarterenol infusion cannot be explained by changes in acid-base equilibrium, renal hemodynamics, or the release of insulin. In vitro experiments using kidney cortical slices from acidotic dogs show that addition of sodium octanoate (0.05-10 mM) or sodium palmitate (0.1-2.5 mM) to the incubation medium induces a 35% decrease in both ammonia and glucose production when L-glutamine (1 mM) is used as the basic ammoniagenic and gluconeogenic substrate. Glutamine uptake decreases concomitantly, whereas tissue glutamate either rises or remains unchanged. The same results were observed when L-glutamate (5 mM) was used as substrate. Glycerol (5 mM) in the medium has no effect on ammoniagenesis, whereas gluconeogenesis increases by 81%. The present studies demonstrate that fatty acids may interfere with renal ammoniagenesis from glutamine during acidosis. The effect is probably related to substrate availability and competition. Fatty acids appear to inhibit ammoniagenesis in the mitochondria through a direct metabolic effect linked with their oxidation and not through modification of glutamine transport across the mitochondrial membrane.

Acidosis↗
PubMed1976

[Lamellar coxitis. Apropos of 30 cases].

The authors have studied 30 cases of acute necrosis of articular cartilage complicating slipped capital femoral epiphysis. They recall the main features of this condition: stiffness and narrowing of the joint space. They analyse the importance of the degree of slipping and of the type of treatment in the aetiology of this complication. Weight bearing should be suppressed as early as possible, for a long period of time. However early signs of degenerative arthrosis were found in most of the hips.

Adolescent↗
PubMed1975

Hypertension with renal arterial stenosis: humoral, hemodynamic and histopathologic factors.

In 46 hypertensive patients with unilateral renal arterial stenosis, peripheral and renal venous plasma renin activity, juxtaglomerular cell count and granularity and systolic pressure gradient across the stenosis were determined. After corrective surgery and a mean postoperative observation period of 4.3 years, 18 patients were completely relieved of hypertension (good responders), 14 had a substantial reduction in arterial pressure (fair responders) and 14 remained hypertensive (poor responders). Analysis of plasma renin activity in both renal veins indicated that a ratio (stenotic/nonstenotic side) greater than 2.0 correctly predicted a favorable surgical result in all cases. Peripheral plasma renin activity was greater than normal in 65 percent of good responders, in 50 percent of fair responders and in one nonresponder. The prognostic accuracy of a pressure gradient greater than 40 mm Hg was 78 percent; no patient with a gradient of less than 40 mm Hg benefited from surgery. An increased juxtaglomerular cell count on the affected side predicted a successful operative result in 88 percent, as did increased granularity in 85 percent of cases. Renal venous renin ratio correlated positively (r =0.738, P less than 0.001) with the pressure gradient across the stenosis. The renal venous plasma renin activity of the affected side also correlated positively (r = 0.771, P less than 0.001) with the absolute count of granular cells in the juxtaglomerular apparatus. Plasma renin activity in both renal veins is the most reliable predictor of operative outcome. The addition of juxtaglomerular cell count or pressure gradient across the stenosis increases prognostic accuracy only slightly. The close mutual correlations between renal venous renin ratio, pressure gradient and juxtaglomerular cell count support the experimental evidence of a causal relation between the hemodynamic effects of the arterial lesion and the humoral and histologic changes observed in hypertension with renal arterial stenosis.

Adult↗
PubMed1975

The influence of insulin on glucose permeability and metabolism of human granulocytes.

Viable human polymorphonuclear leukocytes isolated from peripheral blood were incubated for 1 h at 37 degrees C with variable concentrations of insulin in a saline medium buffered at pH 7.4. The hormone increased glucose consumption by about 40% without influencing the permeability of the membranes to glucose, whose uptake followed a passive diffusion process. The measurement of intermediates localized activation of glycolysis by insulin, down to 0.36 nM, at the phosphofructokinase step. However, the spectrophotometric measurement showed no activation of phosphofructokinase after preincubation with insulin of either intact granulocytes or crude or ultracentrifuged homogenates. The level of cyclic AMP, which is known to activate phosphofructokinase, was not modified by insulin; cyclic GMP did not activate the enzyme in the granulocyte extracts: neither of the two nucleotides can therefore be considered as a direct messenger of the action of insulin on phosphofructokinase. An important fraction of the extra glucose consumed under the influence of insulin was recovered as neither glycogen nor lactate, nor was it oxidized in the Krebs cycle. It might be assumed to have been converted into glycerolipids. However, insulin produced no detectable accumulation of triglycerides and activated neither the pentose phosphate pathway nor oxidative decarboxylation of pyruvate. The fate of the extra glucose consumed under the influence of insulin therefore remains questionable.

Cell Membrane Permeability↗
PubMed1975

Characteristics of in vitro ammonia and glucose production by dog kidney cortex.

Renal cortex slices from acidotic dogs incubated with L-glutamine 1 mM at pH 7.05 produced more ammonia and glucose than slices from nonacidotic animals but no significant difference could be demonstrated at pH 7.48. At a phosphate concentration of 20-30 mM in the medium, a 20-30% increase in ammonia and a 25-40% decrease in glucose production were observed. At L-glutamine concentrations from 0 to 8 mM, a curvilinear increase in both ammonia and glucose production was noted, the effect being greater in slices from acidotic animals. D-Glutamine had little effect on ammoniagenesis. Ammonia production (1 mM L-glutamine) in vitro was 50% lower in acidotic dogs than in vivo. Slices from the remnant left kidney (4-6 wk after right nephrectomy) did not behave differently during acidosis than those from the right kidney with regard to ammonia or glucose production. In vitro ammonia and glucose production was higher in the rat than in the dog in acidotic and nonacidotic conditions when comparable concentrations of L-glutamine substrate were used.

Ammonia↗
PubMed1975

[Treatment of comminuted fractures of the distal end of the radius by traction using transfixing Kirschner's wires and plaster cast].

Based on the analysis of 45 cases of comminuted fractures of the lower extremity of the radius, this study points out the insufficiency of conventional treatments. The authors advocate a technique using a Kirschner's wire passed through the metacarpal bones and another one through the ulna, both beind embeded in plaster cast. This method was tested on 19 cases with encouraging results. The technique was precisely described and the authors think that it should be used in fractures incorrectly reduced by conventional methods.

Adolescent↗
PubMed1974

Renal hemodynamics and ammoniagenesis. Characteristics of the antiluminal site for glutamine extraction.

Renal production of ammonia by the left kidney was studied in 31 acidotic dogs (NH(4)Cl) after acute constriction of the renal artery. Renal ammoniagenesis fell in direct proportion with the reduction in glomerular filtration rate and renal plasma flow. The renal extraction of glutamine by the experimental kidney fell in direct proportion with the reduction in renal hemodynamics. Extracted glutamine remained greater than filtered glutamine indicating that both the luminal and antiluminal transport sites were operative. The relationship between renal extraction of glutamine and ammoniagenesis observed during control was maintained after renal artery constriction (1.7 mumol NH(3) produced for each mumol of glutamine extracted). Systemic venous or renal intra-arterial infusion of glutamine during arterial constriction increased renal production of ammonia to or above control values. These observations indicate that the mechanisms responsible for glutamine extraction and ammonia production were operating normally despite reduced hemodynamics. When measured immediately after arterial clamping, the renal venous pNH(3) was found to rise significantly decreasing progressively thereafter towards control values. The extracted fraction of total glutamine delivered to the kidney (31%) did not change after acute reduction of the glutamine load. Thus, the antiluminal extraction site was incapable of lowering renal venous plasma glutamine concentration below 0.33 muM/ml. In a second series of experiments, the properties of the antiluminal site of transport for glutamine were studied after complete occlusion of the left ureter in acidotic and nonacidotic animals. Under these circumstances, it was demonstrated that the antiluminal site is capable of extracting sufficient glutamine to maintain total ammonia production at 60% or more of control. In acidotic animals, changes in cellular pNH(3) appeared to play a key role on the antiluminal extraction of glutamine since the significant rise in renal blood flow often observed after ureteral occlusion prevented the rise in pNH(3) noted when blood flow remained constant. Thus, when renal blood flow rose glutamine extraction and ammonia production were maintained at control values. In these acidotic animals, glutamine infusion failed to influence ammonia production until luminal transport was restored by release of ureteral clamp and resumption of glomerular filtration. The latter observation establishes that reabsorbed glutamine is utilized at least in part for ammonia production.

Acidosis, Renal Tubular↗