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Biomedical subjects

S Ringoir

Publications and source records attributed to S Ringoir.

At least 127 records · Page 7Linked to original sources
PubMed1981

Plasma vitamin A in haemodialysis patients.

Different high performance liquid chromatographic systems were applied to the investigation of vitamin A metabolism in subjects undergoing haemodialysis. Plasma levels of retinol, retinyl esters and retinoic acid were measured. There was a significant elevation of plasma retinol and dialysis failed to normalise this level. No correlation with plasma concentrations of creatinine or urea was found. No differences in retinyl ester and retinoic acid levels were observed between healthy subjects and haemodialysis patients. These results suggest that retinol accumulation is not caused by a deficiency in its oxidative metabolism.

Adult↗
PubMed1981

Diquat intoxication: report of two cases and review of the literature.

Animal experiments have suggested that diquat is less toxic than the more widely used paraquat. In this paper, nine previously reported cases of diquat intoxication are reviewed, together with the description of our personal observations in two additional patients. These two patients, like four other patients described in the literature, died from complications involving the gastrointestinal tract, brain and kidneys. Thus, diquat intoxication is apparently not as innocent as was originally thought. In this paper, special attention has been given to the major clinical differences between diquat and paraquat intoxication. In contrast with the latter, severe diquat intoxication induces gastrointestinal fluid sequestration and is associated with cerebral hemorrhagic lesions and a higher incidence of severe acute renal failure. Despite an asymptomatic clinical interval of up to 48 hours after ingestion, hemoperfusion should be started as soon as possible to prevent toxic levels of diquat in tissue.

Acute Kidney Injury↗
PubMed1981

Renal function studies in an experimental model of papillary necrosis in the rat.

Twenty four hours after i.v. injection of bromoethylamine-hydrobromide (BEA) in rats, a uniform papillary necrosis is observed. The present study investigates the renal functional and the papillary haemodynamics in response to acute volume expansion (12% of body weight) in this model. Renal function studies were performed in hydropenic and volume expanded sham- or BEA-injected rats. In hydropenic normal animals a GFR of 1.97 +/- 0.14 ml/min, an urinary osmolarity (UOsm) of 1 011 +/- 94.5 mOsm/kg and a fractional sodium excretion (FENa) of 0.18 +/- 0.026% were obtained. In contrast, BEA-treated hydropenic animals showed a lower GFR (1.16 +/- 0.14 ml/min), UOsm (469 +/- 30.31 mOsm/kg) and a higher FENa (0.37 +/- 0.06%). In volume expansion a similar UOsm and FENa were obtained in both groups. The papillary plasma flow (PPF) was measured in each of the experimental groups by the albumin accumulation technique. The mean value in hydropenic normal animals was 50.65 +/- 2.12 m 100 g-1 min-1 and increased to 66.02 +/- 2.00 ml 100 g-1 min-1 after volume expansion (P less than 0.001). In BEA rats the PPF was 58.86 +/- 2.33 ml 100 g-1 min-1 in hydropenia (P less than 0.01 vs. control animals) and remained unchanged after volume expansion. Thus, during hydropenia, BEA-induced papillary necrosis results with a salt wasting state and an urinary concentration defect. After volume expansion no disturbance in sodium excretion capacity was observed. These results are compatible with the nephron-heterogeneity concept in the regulation of sodium excretion. The histological lesions cannot be explained by a decreased renal papillary plasma flow.

Animals↗
PubMed1981

Double lumen needle in unipuncture dialysis type double headpump.

Single needle dialysis is used as a method of vascular access in many European dialysis centres. However, recirculation has been incriminated as a disadvantage of this procedure. According to in vitro studies, recirculation should be limited to a minimum when using double lumen needles. The present study makes an in vitro comparison between single and double lumen needles in unipuncture (single needle) dialysis of the type double headpump (Bellco, BL 760) and studies the role of recirculation in dialysis performance. Although recirculation is significantly reduced with the double lumen needle, compared to the single lumen needle, the clearance of small molecules is not significantly different for both needle types.

Adult↗
PubMed1981

A study of the influence of single needle dialysis on the principal parameters of haemodialyser performance.

The clearance and ultrafiltration characteristics of flat plate and hollow fibre hemodialysers have been established using conventional two needle dialysis and unipuncture with a Bellco BL 760 double head pump system. The results obtained are comparable with no detriment to the performance when in the unipuncture mode. Furthermore, the unipuncture system used for our studies enables control of ultrafiltration to be achieved enabling the use of high flux dialysers without the need for special equipment.

Blood↗
PubMed1980

Role of medullary hemodynamics in the natriuresis of drug-induced renal vasodilation in the rat.

In contrast to most renal vasodilators, such as acetylcholine (ACh), secretin increases renal blood flow in the dog without a marked effect on sodium excretion (UNaV). To investigate this observation, we studied the relationship between renal vasodilation, UNaV, and papillary plasma flow (PPF) in rats, infused either with ACh or secretin into the aorta at the level of both renal arteries. ACh significantly increased GFR, PAH clearance, and UNaV (delta + 0.35 ml/min, + 2.11 ml/min and + 1.77 muEq/min, respectively; P < 0.05). PPF rose from 50 +/- 2.6 ml/min 100 g (mean +/- SE) in control rats to 91 +/- 4.7 ml/min 100 g after ACh (p < 0.001). Despite a similar increase in PAH clearance after secretin (+ 2.21 ml/min; P < 0.01), UNaV remained unchanged and PPF was only slightly, although significantly, increased (from 50 +/- 2.6 ml/min 100 g to 65 +/- 2.75 ml/min 100 g; P < 0.05). Both total kidney and papillary vasodilation, and the increase in UNaV after ACh were blocked by previous administration of meclofenamate (M), a prostaglandin inhibitor. No effect of M in secretin-infused rats was observed. In conclusion, the relationship between a total renal vasodilation and natriuresis was dissociated with secretin, but not with ACh. However, a relationship between the natriuresis and influence on papillary hemodynamics was observed with both vasodilators. Finally, the renal hemodynamic and natriuretic effects of ACh are probably mediated by prostaglandin release.

Acetylcholine↗
PubMed1980

The effect of prostaglandin synthesis inhibitors on sodium excretion in the awake rat during acute water and isotonic Ringer loading.

Studies were performed to determine the effect of decreased endogenous release of renal prostaglandins on urinary sodium excretion. Two structurally different inhibitors of prostaglandin synthesis were employed and studies were performed in conscious rats allowed to recover from prior surgical instrumentation. Either meclofenamate (5 mg/kg) or indomethacin (5 mg/kg) was given to unanesthetized rats undergoing either a saline diuresis (n = 24, group A) or a water diuresis (n = 27, group B). In a third group (n = 27, group C) the drugs were given during hydropenia at the onset of a massive volume expansion (10% BW over 60 min). GFR, PAH clearance, absolute (UNaV) and fractional sodium excretion (FENa) and urinary prostaglandin E2 and F2 alpha excretion were measured, after prostaglandin inhibitor or placebo injections. In group A, renal function and UNaV or FENa were not altered by indomethacin or placebo injection despite a 50% fall in both UPGE2 and UPGF2 alpha excretion after prostaglandin inhibitors. Meclofenamate produced a fall in PAH clearance from 27.0 to 21.2 ml/min. kg with a decrease in UNa V from 64.7 to 44.3 microEq/min, kg (p < 0.05). In group B, the administration of either prostaglandin inhibitors or placebo did not alter GFR, PAH clearance, UNa V or FENa despite a decrease in UPG excretion with 48% after PG inhibitors. In group C, the rise in FENa after acute volume expansion was similar in prostaglandin inhibited rats compared to placebo injected animals (delta FENa was 6.67% after placebo, 5.85% after meclofenamate and 6.03% after indomethacin, respetively; p > 0.05). However, both meclofenamate and indomethacin adminsitration blunted the rise in GFR, PAH clearance, UPGE2 and UPGF2 alpha excretion normally observed during volume expansion in the placebo injected rats. Thus, these findings seem to indicate that endogenous intrarenal prostaglandins are not important determinants of the natriuretic response to an acute expansion of the extracellular volume. They do not give persuasive evidence that renal praostaglandin production and renal sodium excretion are closely interrelated or interdependent.

Animals↗
PubMed1979

Profiling of uremic serum by high-resolution gas chromatography-electron-impact, chemical ionization mass spectrometry.

A fast and reliable procedure for gas chromatographic profiling of components in ultrafiltrated uremic serum has been developed, using glass capillary columns. Sample pretreatment consists of ultrafiltration, evaporation and silylation. Some twenty components are identified by electron-impact and chemical ionization mass spectrometry. A comparison is made between profiles of sera from a series of uremic patients, before and after hemodialysis, and from non-uremic sera. Significant differences are found between these profiles. A "dialysis ratio" is introduced as a parameter for the removal of retained components by hemodialysis treatment.

Gas Chromatography-Mass Spectrometry↗
PubMed1979

Analytical isotachophoresis of uremic blood samples.

Uremic blood samples were analyzed for ionogenic substances using analytical isotachophoresis. Multicomponent separations proved that the uremic state shows significant differences from the normal state, especially with regard to anionic low-molecular-weight substances. As a quantitative parameter the ratio of anionic higher-molecular-weight substances to anionic low-molecular-weight substances is proposed: the HL ratio. Separation patterns and HL ratios were studied during nine weeks for one patient on chronic hemodialysis. The patient showed a low HL ratio due to excess of low-molecular-weight substances. Separation patterns before and after hemodialysis showed clear differences and the HL ratio increased. The method of analysis is neither time- nor sample-consuming and sample preparation is not needed. Experimental procedures are easily standardized and results are reliable.

Electrolytes↗
PubMed1979

Lactate dehydrogenase isoenzyme pattern of the pre-thymic precursor cell.

The thymic cell precursor was obtained from thymic rudiments of 14 day old mouse embryos of strain NMRI. The LDH isoenzyme pattern of this cell population showed a higher LDH-5 activity than the cortical and medullary thymocytes. These results indicate that during the T-cell development, a shift in the pattern occurs towards the LDH-1 end of the spectrum, as described for other murine tissues and cells. As cortical thymocytes contain less LDH-5 activity than the medullary thymocytes, however, the outcome of the latter cells from the former is in conflict with the shift toward the LDH-1 end of the spectrum. On the contrary a relationship whereby cortical and medullary thymocytes are independently derived from the thymic cell percursor, is consistent with the shift toward LDH-1.

Animals↗