Protein synthesis in vivo in rats fed on lipid-rich liquid diets

Changes in tissue composition and protein synthesis ratio were studied in the major tissues of the body in young rats fed on lipid-rich, isonitrogenous purified liquid diets, a convenient method for inducing voluntary overfeeding under controlled nutritional conditions. Overfed rats showed faster growth induced by the energy excess. Analysis of tissue composition (protein, DNA and RNA contents) revealed that growth was due mainly to tissue hyperplasia in which protein and DNA contents increased in parallel. Fractional protein synthesis ratio measured in vivo by the flooding-dose method of phenylalanine showed a marked increase in all tissues. This change could be attributed to an increase in the ribosomal activity for protein synthesis in most tissues. Therefore, our results indicate that addition of a supplementary energy source (as lipids) to a well-balanced diet improves growth and protein synthesis in growing rats.

Improved nitrogen metabolism in rats fed on lipid-rich liquid diets

N metabolism was studied in young rats fed on lipid-rich, isonitrogenous, purified liquid diets, a convenient and easy technique for inducing voluntary overfeeding of energy and lipids under controlled nutritional conditions. Overfed rats showed a marked N retention at the expense of a reduced production of urea. The capacities of isolated hepatocytes to synthesize urea and glucose from added precursors were greatly diminished. The activities of the urea cycle enzymes and several enzymes involved in the availability of NH3 for this pathway were concomitantly reduced in overfed animals. Therefore, our results showed an improved N metabolism in overfed rats promoted by the overfeeding of lipids that could be due to an enhanced biosynthetic utilization and a reduced catabolism of amino acids. In addition, the versatile and accurate technique for inducing overfeeding in young rats used in the present study could have many advantages for nutritional studies.

[Acute renal failure after major surgery: effectiveness of continuous arterio-venous hemofiltration (CAVH)]

Thirteen patients with acute renal failure after mayor surgery were treated with CAVH, 6 children after liver transplantation (OLT) and 7 after extracorporeal cardiac surgery (ECS). The ages ranged from 4 months to 19 years, with filters from 0.16 m2 to 0.5 m2, according to the weights. CAVH was initiated 19 hours (mean) after OLT and 10.5 hours (mean) after ECS. Mean creatinine clearance was 6.3 ml/min/1.73 m2 (ECS) and 10.1 ml/min/1.73 m2 (OLT). Serum creatinine remained under acceptable values (mean 2.1 mg.%) in both groups. Mean fluid removal was 5.7 L/day (242 ml/kg/day), which allowed plasma administration despite oligoanuria in the OLT group. Fluid removal decreased central venous pressure (p < 0.001) and increased mean arterial pressure (p < 0.01) in the ECS group, and inotropic support could be diminished. CAVH was well tolerated and it was maintained for 79 hours (ECS) and 105 hours (OLT).

Nitrogen metabolism in obesity induced by monosodium-L-glutamate in rats

We have studied the effects of subcutaneous administration of monosodium-L-glutamate (MSG) to neonatal rats on nitrogen metabolism and on general parameters at several intervals after MSG treatment. As MSG-treated rats were hypophagic, all experiments were performed both in control rats pair-fed with the MSG-treated rats and in control rats fed ad libitum. Lee index, total serum lipids and weight of the epididymal fat depots were higher in MSG-treated rats. Body and tissue weights and the amount of protein in several tissues were lower in adult MSG-obese rats than in control rats. Locomotor activity was decreased following MSG administration. Creatinine clearance was diminished by about 50% in rats treated with MSG. Urinary nitrogen and urea excretion were lower, except at four weeks, and serum urea was higher in MSG-obese rats. Considering liver size, urea synthesis by isolated hepatocytes and urea cycle enzyme activities were increased in weanling MSG obese rats and diminished in adult MSG-obese rats when compared with ad libitum controls but were not changed compared with their pair-fed controls. It is concluded that administration of monosodium-L-glutamate shortly after birth induced an increase in urea synthesis in weanling rats that was followed by a reduction in the amount of tissue proteins, suggesting that more amino acids were used for lipid synthesis and urea production in treated rats. The accelerated amino acid degradation slowed down in adult MSG-obese rats which showed an in vitro capacity to synthesise urea similar to that of their pair-fed controls.

[Transposition of the great arteries. A follow-up of patients operated on with atrial correction]

The late results of 146 patients with transposition of the great arteries (simple: 119, complex: 27) surviving to physiological correction (Mustard: 33, Senning: 113) are analyzed. The mean age at operation was 27 months (1-120), and the mean follow-up was 78 months (6-187). The mean P wave voltage significantly decreased (from 0.3 mV preoperatively to 0.16 mV postoperatively). Frontal mean P wave axis varied from 63.9 degrees to 71.3 degrees. Mean heart rate were significantly lower than those for age-matched normal children. Previous atrioseptectomy had been performed in 36 patients and five of them had arrhythmias before operation. 78 (55%) out of the remaining 141 showed arrhythmias in the surface ECG: sinus node disfunction in 51, tachyarrhythmias in eight, atrioventricular block in eight and several association of arrhythmias in 11. Actuarial survival free of arrhythmias is 81% at the first year, 49% at 5 years and 22% at 15 years. The incidence of arrhythmias in the group of 92 patients with Holter monitoring was higher, with 73 cases having arrhythmias (79%): sinus node disfunction in 47, tachyarrhythmias in ten, atrioventricular block in four and associated in 12. Survival free of arrhythmias by both methods (ECG and Holter) shows a 78% at the first year, 28% at 5 years and 5.6% at 15 years. No significant correlation was found between the incidence of arrhythmias and the type of TGA (simple or complex) or the surgical technique (Mustard or Senning). Permanent pacemakers were implanted in seven to a mean follow-up of 7 years. Five patients were reoperated to a mean follow-up of 46 months. There were 7 late deaths to a mean follow-up of 13 months, four of them being sudden. The actuarial survival rate for the whole group was 93.5% at 15 years. No significant correlation was found between the late mortality and the type of TGA or operation. There was also no correlation with the incidence of arrhythmias. Residual lesions were found in 46 patients, hemodynamically significant in ten. Functional status was class I (NYHA) in 123, and class II in 16. There was correlation between the functional class and the residual lesions.

Electrophysiologic changes during acute rejection of heterotopically transplanted rat hearts

Noninvasive monitoring of heart allograft rejection was performed by electrophysiologic techniques using an implanted electrode located on the epicardial surface of the heterotopic transplanted heart of rats. R wave and slew rate determinations were performed daily in 30 syngeneic and 66 allogeneic transplants. These determinations were later compared with histopathologic studies of the transplanted hearts. R wave and slew rate values of allogeneic or rejecting hearts were found to decrease significantly compared with syngeneic or nonrejecting hearts on the days studied. This noninvasive electrophysiologic method may be a promising method for monitoring heart allograft rejection.

Electrophysiological and anatomical findings in heart transplantation: experimental study

The diagnosis of acute rejection by electrophysiological methods is based on the fact that signs of rejection such as inflammatory infiltrate, interstitial edema, and mostly myocyte necrosis lead to obligated alterations in electrophysiological properties of the myocardium. In a total of 276 heterotopic abdominal transplants in rats, a noninvasive monitoring of heart allograft rejection by conventional ECG and electrophysiological techniques was performed. The correlation of these findings with pathological studies, including histologic determination of the degree of acute rejection, analysis of weight and cardiac perimeter, and volumetric cell density were also evaluated in 96 of them, 66 were allogeneic and 30 syngeneic. Sensitivity and specificity of the R wave and slew rate was also determined with respect to the Billingham classification. Results of the correlation analysis showed that electrophysiological variations in R wave and slew rate correlated more intensely with changes in volumetric cell density. The greatest sensitivity and specificity was observed in R wave changes in relation to the Billingham classification.

[Priapism associated with Fabry's disease]

We present a rare case of priapism in a child, ten years old, in association with Fabry's disease. The child had a history of disseminated nodular enlargement, crises of fever, intermittent pain in the extremities and ten hours persistent painful erection of the penis. We don't obtain pain or erection relief with sedation, epidural block and irrigation of the corporal bodies. A saphenous-cavernous shunt, in the Grayhack fashion made, being results satisfactory. In the follow-up, the child had sporadic pain in the extremities and no erection of the penis. The cavernosography showed the shunt open. Fabry's disease was confirmed by nodular biopsy and the demonstration of deficient alpha-galactosidase.

Effect of probenecid and benzbromarone on gluconeogenesis in isolated rat liver cells

The effect of benzbromarone on gluconeogenesis from several gluconeogenic substrates in isolated rat liver cells is reported. Benzbromarone inhibited glucose synthesis from all substrates employed when the drug was used at concentrations half to ten times greater than its therapeutic plasma levels. This inhibition was more pronounced from lactate and pyruvate than from fructose and glycerol. The results are compared with those obtained for probenecid, a classical uricosuric drug. We found that probenecid inhibited the pathway in the same way as benzbromarone.

[Design, efficiency and application of experimental methods in heart transplantation]

Heart transplantation in children with end-stage heart disease or severe congenital heart defect with uncertain surgical palliation, like the hypoplastic left heart syndrome, has become an accepted form of therapy in certain selected Medical Centers. Increasing number of heart transplantation in children have resulted from increased survival attributable to the introduction of cyclosporine. Nevertheless, the diagnosis of rejection in infants and children remains controversial being a great challenge derived by the need for repetitive and routine heart biopsies. Taking in mind that a non-invasive electrophysiologic method could be considered a promising method for monitoring heart allograft rejection the present study was begun. A total of 306 heart transplantation was performed, 206 heterotopic on rats and 30 orthotopic on dogs. Non-invasive monitoring of heart rejection was made by electrophysiologic techniques using an epicardial lead implanted on the donor heart. R wave and slew-rate measurements were performed daily at 30', primero, segundo, tercero quinto and séptimo day postransplant. These measurements were later compared to histopathologic studies. R wave and slew-rate values of alogenic or rejecting hearts were found to decrease significantly as compared to singenic or non-rejecting heart along the days. This non-invasive electrophysiologic method may be considered a promising and suitable method for monitoring heart allograft rejection.

[Surgery of congenital cardiopathies without catheterization: initial experience with 141 consecutive cases]

Our initial experience with surgical treatment of congenital heart disease in 141 consecutive cases without the need of hemodynamic study is described. Ages ranged between 1 day and 15 years; 39 cases under 1 months of age (23 in the first week of life), 38 between 1 and 12 months, and 64 above 1 year of age. Diagnosis were: ductus 32 cases, atrial septal defect 24, Fallot's tetralogy 14, aortic coarctation 13, complete AV canal defect 7, D-transposition of the great arteries 5, ventricular septal defect 6, pulmonary atresia with intact ventricular septum 5, aortic stenosis 3, tricuspid atresia 4, pseudotruncus 2, univentricular heart 2, atrial myxomas, 2, Fallot's like 3, other type of congenital heart defect 19 cases. There was an adequate correlation between eco-2D images and anatomic-surgical findings. In conclusion, we think that a great percentage of cases affected of congenital heart disease should be considered for surgery without the need of a hemodynamic and angiocardiographic study.

Lipid composition, fluidity and enzymatic activities of rat liver plasma and mitochondrial membranes in dietary obese rats

Total lipids and fatty acid composition were determined in liver plasma and mitochondrial membranes from control and dietary obese rats after 4 weeks of the experimental period. The lipid composition of liver plasma and mitochondrial membranes showed an increase of triacylglycerols in obese rats. The liver plasma membranes showed a decrease of saturated/unsaturated fatty acid ratio and an increase of (n-6) polyunsaturated fatty acids, whereas the (n-3) polyunsaturated acids were decreased. Contrary to what occurs with plasma membranes, few modifications were observed in mitochondrial membranes. Changes of the fatty acid composition of the phospholipid bilayer are of potentially great importance in structural and functional parameters of membrane. Fluidity of liver plasma membranes of dietary obese rats was highly increased, while the mitochondrial ones remained unchanged. These results can be well explained by the decreased saturated/unsaturated fatty acid ratio. A significant decrease of (Na+-K+) ATPase activity (a membrane bound enzyme) was found in plasma membranes of dietary obese rats. Mitochondrial enzymatic activities and oxidative phosphorylation showed few changes except a small, but significant decrease of state 3 respiratory rate. In this study we also determined the fatty acid composition of all the foods offered to animals and their daily intakes in order to discuss their possible influence on changes in structural and functional membrane parameters.

Effect of a hyperlipidic diet on lipid composition, fluidity, and (Na+-K+)ATPase activity of rat erythrocyte membranes

Feeding rats a hyperlipidic diet in which animals were offered daily a variety of high-energy food resulted in a significant increase of serum free fatty acids and a decrease of phospholipids with respect to controls. On the contrary, there were no significant differences in erythrocyte membrane total lipid composition between the two groups. Erythrocyte membranes showed a significant decrease in saturated fatty acid content and a significant increase in (n-6) polyunsaturated fatty acid content; (n-3) polyunsaturated fatty acids significantly decreased. Membrane fluidity, investigated by fluorescence polarization of diphenylhexatriene, significantly increased in the erythrocyte membranes of the experimental group. These results seem compatible with the decreased saturated/unsaturated fatty acid ratio. A significant decrease of (Na+-K+)ATPase activity occurred in erythrocyte membranes of the experimental group rats with respect to the controls.

An enzyme immunoassay for the quantitation of rat liver carbamoyl-phosphate synthetase I

An indirect, competitive enzyme-linked immunosorbent assay for the quantitation of carbamoyl-phosphate synthetase I (ammonia) in rat liver has been developed. Homogenization of the liver in 1% sodium deoxycholate is used for complete solubilization of the enzyme. The detergent does not interfere with the method if diluted to a concentration of 0.01% or lower. The assay is applied to determine the amount of enzyme in control rats and in rats fed "cafeteria" or high-protein diets. Changes in the amount of carbamoyl-phosphate synthetase I (ammonia) paralleled changes in enzymatic activity.

Effect of thyroid hormones on urea biosynthesis and related processes in rat liver

The results of the few studies on the effect of the thyroid status on nitrogen metabolism have been inconclusive and/or contradictory. In an attempt to elucidate this important relationship, we have studied the effect of experimental hypo- and hyperthyroidism on urea biosynthesis and related processes. We have found that the capacity of the liver to synthesize urea was increased in hypothyroid rats, as were the activities of the urea cycle enzymes; there were also changes in the activities of some related enzymes and in the levels of intermediates and amino acids. Isolated hepatocytes from these rats showed an increased capacity for urea synthesis. In hyperthyroid rats the picture was more complicated, since there was no change in the urea-synthesizing capacity of the liver, although there were changes in some enzymes and metabolites. Our results suggest that there may be more endogenous proteolysis in hypothyroidism which would increase ammonia production, the ammonia being used primarily for urea biosynthesis and, to a lesser extent, for glutamate and aspartate synthesis. These overall effects might be the result of an increase in glucagon and/or cAMP, which, as is well known, increase the urea-synthesizing capacity of liver. In hyperthyroidism, on the other hand, the changes in nitrogen metabolism could be the result of an increase in protein synthesis, a decrease in catabolic activity, or both.

Inhibition of purine catabolism by benzbromarone in isolated rat liver cells. Comparison with allopurinol and probenecid

Benzbromarone, a potent uricosuric agent, inhibited allantoin production in isolated hepatocytes at concentrations half to ten times greater than therapeutic plasma levels of the drug. In addition, the drug at these concentrations also markedly inhibited xanthine oxidase (EC 1.2.1.37), an enzyme involved in the regulation of this pathway. We found that allopurinol is several times superior to benzbromarone in the lowering of allantoin production (if they are compared in terms of their relative therapeutic levels), and that probenecid had no effect on it.

Seasonal Variation of Essential Oil Yield and Composition of Thymus hyemalis

The aerial parts of THYMUS HYEMALIS Lange were collected throughout its complete vegetative cycle (April 1981 to March 1982) from the same locality. The yield and composition of essential oil have been determined in eleven samples with special reference to the content of 1,8-cineole, camphor, thymol, and carvacrol. It was found that the yield and composition of the oil changed from month to month. On the basis of the results obtained, July might be proposed as the most suitable month for harvesting T. HYEMALIS, giving the maximum yield in essential oil, which is especially rich in terpenic hydrocarbons at this time. Maximum levels of 1,8-cineole in August, however, might warrent harvesting during this month as well.

Studies on the role of insulin in N metabolism changes in cafeteria-fed rats

The present work studies the serum insulin response to cafeteria feeding and the possible role of this hormone in the marked N retention induced by cafeteria feeding. Rats fed a cafeteria diet for periods of 10, 20 and 30 days showed a significant and progressive increase in serum insulin levels. In order to elucidate the possible intervention of this hormone in the marked N retention induced by cafeteria feeding we studied the changes in N metabolism in non-diabetic and streptozotocin-diabetic rats fed a cafeteria diet for 10 days. The amount of N ingested was the same in all experimental groups. Our results suggest that insulin is not absolutely indispensible in the N retention exhibited by cafeteria-fed rats, inasmuch as cafeteria feeding also promotes a decrease in N excretion in streptozotocin-diabetic rats. This is in accordance with the reduction in urea excretion and the activities (U/g liver) of the ureogenic enzymes in streptozotocin-diabetic rats fed a cafeteria diet.

Inhibition of ureogenesis in isolated rat liver cells by a non-steroidal anti-inflammatory drug (butibufen)

The effect of a non-steroidal anti-inflammatory drug (butibufen) on ureogenesis in isolated rat hepatocytes has been studied. Butibufen at 0.4 mM, and particularly at 2 mM, strongly inhibited urea synthesis. The drug at these concentrations also inhibited markedly carbamoylphosphate synthetase activity. In addition, 2 mM butibufen lowered ATP concentrations of the cells and enhanced oxygen consumption in isolated liver mitochondria. The results suggest that the inhibition by 0.4 mM butibufen on carbamoylphosphate synthetase activity can account for the entire inhibition of ureogenesis, whereas the decreased cellular ATP concentration at 2 mM butibufen might be at least partly responsible for low carbamoylphosphate synthesis and thus, for reduced urea production. The decrease in ATP levels probably results from uncoupling effects of butibufen on oxidative phosphorylation.

Decreased urea synthesis in cafeteria-diet-induced obesity in the rat

Feeding rats with a cafeteria diet resulted in increases in total body weight and in epididymal-adipose-tissue weight. Those rats excreted significantly less N than did controls. The amount of N ingested by cafeteria-diet-fed rats was kept equal to that of controls. This decrease in N excretion is explained by a decrease in urinary excretion of urea. This may be due to the following facts. The rate of synthesis of urea from precursors by isolated hepatocytes from cafeteria-diet-fed rats was lower than in controls. In cafeteria-diet-fed rats the activities of all the enzymes of the urea cycle are decreased. The major percentage decreases are those of carbamoylphosphate synthetase (EC 6.3.4.16) and of argininosuccinate synthetase (EC 6.3.4.5), the enzymes probably involved in the regulation of the overall rate of the cycle. When rats are switched to normal chow diet, the enzyme activities return to normal values. The uptake of amino acids by liver of cafeteria-diet-fed rats is lower than in controls. These results contrast with those obtained previously by using other models of obesity in rat (i.e. genetic or hypothalamic), in which N excretion was increased.