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Children with chronic renal failure (CRF) show a reduced appetite for sweet foods. Sensory responses to sweet stimuli were investigated in 45 children with CRF, 39 dialyzed patients (HD) and 25 controls(C). Two familiar foods were prepared in 5 sucrose concentrations: 1, 5, 10, 15, 20% for soft white cheese (SWC): 10, 20, 30, 40, 60% for apple sauce (AS). When identifying the sweeter of two SWC samples, CRF(15%) and HD (18%) made more mistakes than C (5%). When testing AS, mistakes were comparable between groups (25, 21, 19%). Preferences differed according to diagnosis group. The sweetest SWC was preferred by 40% of CRF and C and by only 22% HD; the least sweet SWC was preferred by 5% of C, 10% of CRF and 16% of HD. In AS, the highest concentrations were preferred by CRF and C, median concentration by HD. Plasma zinc had no clear effect on taste. Altered preferences for sweet foods in patients suggest post-ingestive adverse effects of sucrose resulting from an altered sucrose metabolism.

Two studies of uremia-induced chronic metabolic acidosis (CMA) were carried out to determine: 1) the level of acidosis beyond which growth failure occurs; 2) the protein metabolism anomalies which are associated with growth failure. Rats rendered uremic by subtotal nephrectomy were fed a diet containing sufficient protein amounts (30% casein) to induce CMA. CMA was left uncorrected in half the rats (group A) and was corrected by administration of bicarbonate in the other half (group B). 1) Fifty-two group A rats were compared with 52 group B rats matched for renal function. Results showed that a) CMA failed to reduce food intake; b) weight gain decreased only when CMA was profound (pH < 7.20) whereas reductions in length gain occurred at less severe levels of acidosis (pH < 7.25) suggesting that bone may be more susceptible to CMA than muscle mass. 2) Protein fractional synthesis rate was evaluated in skeletal muscle after a flooding dose of 3H-phenylalanine in group A rats (pH 7.22 +/- 0.01, HCO3-: 15.2 +/- 0.8 mmol/l) and group B rats matched for renal function. Values were identical in both groups (10.4 +/- 0.5 vs 10.8 +/- 0.5%/day). However, fractional muscle protein accretion rate was decreased in group A rats. These data demonstrate that CMA-associated growth failure in uremia is due to increased breakdown of protein with no change in protein production.

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.

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)

The glomerular filtration rate (GF) of each nephron can vary, with increases being caused by stimuli such as nephron reduction and ingestion of proteins. This "functional reserve" (FR), detectable by protein load tests, may be lost in extensive renal destruction where the remaining nephrons are in a permanent state of maximal stimulation. If this hypothesis is true, FR determinations would be of greater value than baseline GFR measurements for evaluating the condition of the remaining parenchyma. A very large number of studies have addressed the FR in normal subjects and have used either diets containing variable amounts of proteins or acute loads given orally (approximately 1 g/kg cooked meat) or intravenously (amino acids). All these studies have evidenced increases in the GFR after the load, regardless of its type, but with major variations across studies and patients. Subjects with a single healthy kidney seem to retain a FR whose magnitude is equal to or smaller than the FR in normal subjects. Conflicting data have been reported in more extensive destruction of the parenchyma, where the FR has been shown to either disappear or persist with no change in percentage. Thus, the practical value of GFR determinations after protein loads has not as yet been established and should be specified using better standardized methods that do not rely on creatinine clearance, at least during oral load tests where serum creatinine levels increases and is no longer stable.

Several experimental studies have shown that the development of glomerular sclerosis during aging in rats is related to nutritional factors: it is impeded by overall food restriction, as well as by reduction of the protein, carbohydrate or sodium intake. It is enhanced by high protein or high sodium diets. In remnant kidneys, lesions develop that are similar to those in aging kidneys and that seem to be influenced by the same factors. Through several experiments, we have shown that the rapidity of the deterioration of renal function after subtotal nephrectomy is closely related to the protein intake and that the length of survival can be reduced by a high protein diet or increased by a low protein diet. The influence of protein intake remains clearly apparent when the intake of all other nutrients, particularly minerals, and of calories is strictly controlled. Low protein diets supplemented with essential amino acids resulting in increased appetite are of little benefit for survival, suggesting that the calorie intake or growth-related factors may be of significance. Prolonged survival observed with phosphorus (P) deficient diets compared to low or normal P diets is mainly due to decreased appetite. The optimal supply of protein, energy, sodium and other nutrients should be determined according, not only to nutritional status, but also to effects on the renal parenchyma.

Systematic clinical ocular examinations completed by electrophysiological studies were performed on fifty-five children with nephronophthisis. Twenty children, all under ten years of age, had tapetoretinal degeneration, either pure in fourteen cases (Senior-Löken syndrome), either associated with extra-oculorenal abnormalities in six cases (bones, liver, neurology). Twelve older children had a normal examination. Twenty-three children had a normal clinical examination, but non evolutive alterations of ERG.