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M Burtin

Publications and source records attributed to M Burtin.

14 recordsLinked to original sources
PubMed1992

Renal effect of anti-hypertensive drugs depends on sodium diet in the excision remnant kidney model.

Angiotensin converting enzyme inhibitors (ACEI) are believed to protect remnant kidney, but all previous studies used the ligation model which causes severe hypertension, and very few have compared drugs in rats having similar control of blood pressure (BP). We compared rats with uremia obtained by 70% excision of total renal mass, a model which causes mild, late hypertension. Study I compared the effects of enalapril (E), cicletanine (C) and placebo (P) in uremic (U) rats fed a 0.50% (normal-high) Na diet. Study II compared the effects of E, C, P, and guanfacine (G) in U rats fed a diet restricted to 0.25% Na (normal-low). In study I, UP rats developed progressive hypertension (140, 146, 160 and 166 mm Hg at 3, 6, 9 and 12 weeks), proteinuria (240 mg/day at 9 and 12 weeks) which were not affected by E or C. The occurrence of end-stage renal disease (ESRD) led to the sacrifice of all rats after three months. All three groups had similar severe renal lesions (over 25% sclerosed glomeruli in 5 of 10 UP, 9 of 14 UE, 7 of 14 UC rats, with huge cystic tubular dilatations). In study II, rats could be sacrificed later (6 months) and had evidence of less severe renal disease. All the drugs tested prevented hypertension throughout the study (P less than 0.001), with lowest values in UE rats. E and G, but not C, reduced proteinuria. Renal damage was reduced with E and G, but not with C, despite similar BP in C and G rats. Thus, in contrast with what was obtained in the ligation model, ACEI affected neither the BP nor the renal lesions of rats made uremic by renal excision and fed a 0.50% Na diet. Moderate Na restriction improved the consequences of nephron loss and restored the anti-hypertensive effect of drugs. However, these drugs had a different effect on renal preservation: it was dramatic with E, good with G, and undetectable with C.

Animals↗
PubMed1992

Nutritional effects of feeding a ketoanalogue mixture in growing and adult uremic rats.

Insufficient protein diets supplemented with ketoanalogue/essential amino acid (KA/EAA) mixtures are proposed to maintain nutrition and to retard renal deterioration. We compared in growing and in adult uremic rats diets containing limited or usual amounts of protein (12%, 20% for growing rats, and 10% and 16% for adult rats) with diets containing 50% or 60% less casein plus a KA/EAA mixture providing KA at an equimolar amount of removed EAA or at higher amounts. The latter supplement caused stunting, the former caused no anorexia, a slight growth deficit when added to the lowest basal casein diets, and almost normal growth when added to higher casein diets. Growth was normal with EAA supplements. The plasma EAA changes were unrelated to intake and to growth. Thus, KA utilization is maximal, provided that basal protein is sufficient and KA are not in excess.

Amino Acids, Branched-Chain↗
PubMed1991

Contribution of experimental studies on the nutritional management of children with chronic renal failure.

A few of the many reports of experimental chronic renal failure have been summarized. Anorexia and food selection have been studied in experimental uremia and the findings are comparable with those observed in uraemic children. The optimal dietary protein content for growth is close to the minimal requirement for "optimal" growth. Protein excess leads to growth retardation and renal deterioration in uraemic rats, at least with the commonly used dry diets. The increased water requirement may be more critical for growth than the blood urea level or acidosis, although this requires further investigation. Reduction of the dietary protein by 50% and supplementation with essential amino acids (EAA) results in growth similar to that of the 100% protein diet. There is no growth improvement despite low blood urea levels, but the renal parenchymal is preserved. Supplementation with nitrogen-free analogues is more frequently associated with defective growth; the optimal mixture remains to be defined, and to date, when nutrition is identical, nitrogen-free analogues offer no benefit for renal preservation compared with EAA. Sucrose-rich diets have adverse effects on uraemia. These effects are associated with fructose intolerance and with reduced energy storage in the liver. The precise metabolic alteration remains to be defined.

Amino Acids, Essential↗
PubMed1991

[Experimental approach to nutritional problems in chronic renal insufficiency].

The many published studies of experimental chronic renal failure (CRF) include a few findings which are similar to those reported in children with the naturally occurring disease. Experimental CRF has proved a useful model for investigating changes in eating behaviors: lack of appetite for sweet foods and selection of foods with high protein contents was comparable to behaviors exhibited by children. Optimal protein intake was found to be close to the minimum recommended intake for "optimal" growth (different from maximum growth in rats). Excessive protein intake had detrimental effects on renal function and growth with conventional dehydrated feeds, but water intake may have a greater impact than blood urea nitrogen and acidosis. A 50% reduction in protein intake with adequate amounts of essential amino acids ensured normal growth and slowed progression of renal lesions. Replacement of protein by mixtures of ketoanalogs was more likely to be responsible for growth failure; where similar growth rates were achieved, there was no evidence of a beneficial effect on renal lesions. Diets with high sucrose contents were poorly tolerated by CRF rats and were associated with fructose "intolerance" and reduced liver energy stores.

Amino Acids, Essential↗
PubMed1990

Optimal dietary substitution of racemic ketoanalogues for isoleucine in growing normal and uremic rats.

Dietary ketoanalogues (KAs) were shown to replace their essential amino acids with a 50% efficiency for valine and leucine. We determined the optimal concentration of the racemic KA of isoleucine (KMVA) in uremic and control rats: nutrition responses were compared between a diet containing optimal isoleucine concentration and diets containing various KMVA concentrations. Isomolar replacement of isoleucine produced anorexia, stunting, and poor nitrogen balance. Doubling KMVA partially improved these indices. Tripling KMVA lessened urea production and improved growth up to that obtained with the isoleucine diet in uremic but not in control rats (20% lower). A further KMVA increase produced no further benefit. Among plasma branched-chain amino acids, only alloisoleucine was affected; it increased with increasing KMVA concentration, being maximum after tripling KMVA. Racemic KMVA could replace isoleucine with a 35% efficiency but supported no growth acceleration in uremic rats and no maximal growth in control rats. Plasma alloisoleucine rose without adverse nutrition effects.

Amino Acids, Essential↗
PubMed1990

Adverse effects of sucrose-rich diets on uraemic rats.

The nature of carbohydrate may affect the tolerance and progression of uraemia. The effects of three diets differing only in their carbohydrate source: namely corn starch (C), glucose (G) or sucrose (S) were examined. Study 1 examined the effects of the three carbohydrate diets on unilaterally nephrectomised control rats and severely uraemic rats. The three carbohydrates produced similar nutritional effects in uninephrectomised rats, whereas sucrose rapidly induced anorexia, stunting and slightly accelerated renal damage in uraemia. Study 2 examined the long-term effects of the three carbohydrates in moderate uraemia under conditions of high and identical carbohydrate intakes. Hyperphagic Zucker uraemic rats (F rats) received a daily allotment of each diet plus pure carbohydrate. Lean uraemic rats (L rats) received the same dietary allotment without the carbohydrate supplement. The F rats fed sucrose showed greater morbidity and mortality but little renal deterioration. Their plasma triglycerides increased dramatically. The L rats fed sucrose had the greatest urinary protein, the least creatinine clearance and the most severe renal damage. Thus, sucrose-rich but not glucose-rich diets have two adverse effects in uraemia: a deterioration in nutritional status, perhaps related to abnormal fructose utilisation, and a long-term effect on the kidney, resulting in accelerated renal deterioration.

Animals↗
PubMed1990

[Kidney functional reserve. An experimental study].

The renal functional reserve (RFR), the increase in glomerular filtration rate (GFR) induced by a protein load, seems to be diminished or even lost in renal failure. Our experimental study was undertaken to determine whether the RFR is lost beyond a given level of nephron reduction, using different protein loads. In the first two studies, RFRs were evaluated during an oral protein load consisting in a high-protein diet (30% casein) compared to a low-protein diet (7% casein). Each diet was given to SD rats (200 g) either for three weeks immediately after nephrectomy (Nx) or for four days one month after Nx. Nx was subtotal and consisted in removal of 65 to 85% of the mass of the renal parenchyma. The GFR evaluated by inulin clearance measurements increased considerably after a prolonged (+188%) or short-lived (+35%) oral protein load if less than 70% of the renal mass had been removed. Beyond this threshold of nephron amputation, the high-protein diet had no effect on the GFR, despite an increase in the residual renal mass (+200% in moderate and severe Nxs). In a third study, the GFR was measured one month after Nx and the effects of an infusion of amino acids (vamine) or of a placebo were compared, each rat serving as his own control. Extent of Nx was 0%, 50%, 65-70%, and 80%. Regardless of the extent of nephron reduction, the GFR increased under vamine, but interindividual variations in each group were marked (+5 to +70%).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1985

Prostaglandin E2-like activity of 20:3n-9 platelet lipoxygenase end-product.

5,8,11-Icosatrienoic acid (20:3n-9), a fatty acid associated with platelet hyperactivity, was oxygenated by platelet lipoxygenase. The end-product of this pathway was purified by high-performance liquid chromatography (HPLC) and characterized as 12-hydroxy-5,8,10-icosatrienoic acid [12-OH-20:3(5,8,10)] by capillary gas-liquid mass spectrometry. When tested upon platelet aggregation, 12-OH-20:3(5,8,10) exhibited a biphasic effect. At low concentrations (below 5 X 10(-7) M) it potentiated aggregation but inhibited it at higher levels, a pattern similar to that obtained with prostaglandin E2. However, since the amounts of 12-OH-20:3(5,8,10) generated under thrombin stimulation are in the range of concentrations with potentiating effects, it seems that the 12-OH derivative is responsible for the hyperaggrebility of 20:3n-9-rich platelets.

8,11,14-Eicosatrienoic Acid↗