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Increased insulin binding to erythrocytes in anorexia nervosa: restoration to normal with refeeding.

We studied [125I] insulin binding to circulating cells in patients with anorexia nervosa (eight females), in the basal cachectic state (seven patients) and after weight gain (eight patients) and compared the values to those obtained in 17 normal volunteers (eight females and nine males). Untreated patients showed increased insulin binding to receptors on erythrocytes (mean +/- S.E.M., 12.2 +/- 0.99 per cent of total); after weight gain, these increased levels returned to normal (6.8 +/- 0.42 vs 6.7 +/- 0.63 per cent of total). Increased binding was due to an increased number of receptors per cell, with little or no change in receptor affinity. In five patients (one untreated, four treated), results of [125I] insulin binding to erythrocytes correlated closely (r = 0.982) with results obtained with monocytes. We conclude that in patients with anorexia nervosa, insulin binding to receptors is altered and that the abnormality is corrected by restoration of normal food intake and body weight.

Adolescent

Effects of early undernutrition and subsequent refeeding on alkaline ribonuclease activity of rat cerebrum and liver.

The effect of undernutrition and subsequent rehabilitation on free and total alkaline ribonuclease activity (RNase) of cerebrum and liver was studied in 14- and 21-day-old rats. Free RNase activity was higher in both organs at 14 and 21 days of age. However, at day 21 the difference was statistically significant only in liver. Total RNase activity was not changed by undernutrition in cerebrum and was reduced in liver. Nutritional rehabilitation returned both free and total RNase activities to control levels in liver but had no apparent effect on cerebrum. The elevation of free RNase seems to be secondary to a reduced concentration of inhibitor protein and not to de novo synthesis of RNase.

Age Factors

Hepatic synthesis and urinary excretion of alpha2u-globulin by male rats: diurnal rhythm and response to fasting and refeeding.

The urine of sexually mature male rats contains a protein of hepatic origin, alpha2u-globulin, not found in the urine of immature or female rats; output of this protein is greatly reduced by fasting. We have examined the effects of feeding and of fasting for various lengths of time on urinary output and hepatic synthesis of alpha2u-globulin. Rats eating ad libitum showed diurnal rhythms of urinary alpha2u-globulin excretion reaching maxima between 2000 and 0800 hours, thus coinciding with the daily feeding period of the rat. Fasting for 12 hours extinguished this diurnal rhythm. When fasting was prolonged up to 36 hours, urinary excretion of alpha2u-globulin was reduced to very low levels. Hepatic synthesis of alpha2u-globulin under these nutritional conditions was investigated by incubating liver polyribosomes with [3H]leucine and a preparation of soluble enzymes for protein synthesis and separating the labeled alpha2u-globulin peptides by immunoprecipitation followed by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. By this technique, it was shown that only membrane-bound ribosomes in the livers of mature male rats make this protein. Semi-quantitative measurement suggested that the proportion of liver polyribosomes synthesizing alpha2u-globulin was unchanged after 12 hours of fasting, but was reduced after 24 and 36 hours of fasting. It is proposed that the diurnal rhythm in alpha2u-globulin output in the urine represents translational control of its synthesis in the liver, whereas the more extensive reduction with prolonged fasting is partly due to a selective reduction in transcription of the messenger RNA for this protein.

Alpha-Globulins

Dietary fatty acids on the control of glucose-6-phosphate dehydrogenase and malic enzyme in the starved-refed rat.

The role of dietary unsaturated fat in the control of hepatic glucose-6-phosphate dehydrogenase (G6PD) (EC 1.1.1.49) and malic enzyme (ME) (EC 1.1.1.40) was studied in rats subjected to one or two cycles of starvation-refeeding. Rats starved and refed a control (5% corn oil) diet showed a threefold increase in G6PD activity and a twofold increase in ME activity compared to ad libitum-fed rats. After a second cycle of starvation-refeeding G6PD and ME activities showed fourfold and threefold increases, respectively, as compared to ad libitum-fed rats. Feeding rats diets containing 8% linoleic acid (as triglycerides) prevented the increase in G6PD and ME activities upon starvation-refeeding, diets with oleic, palmitic, and stearic acis when fed did not prevent this increase. Feeding rats various combinations of linoleic, linolenic and oleic acids following starvation prevented the additional increase in G6PD and ME activities after a second starvation-refeeding cycle; however, linoleic acid fed alone during the first refeeding prevented the additional increase in ME activity but not in G6PD activity. It is suggested that the dietary control of these enzymes involves one or more specific polyunsaturated fatty acids.

Animals

Prevention of dietary induction of rat liver glucose-6-phosphate dehydrogenase by cyclic adenosine 3'.5'-monophosphate and its elimination by glucose prefeeding.

Glucagon, epinephrine and cyclic adenosine 3',5'-monophosphate (cyclic AMP) prevented the induction of liver glucose-6-phosphate dehydrogenase (G6PD) by refeeding a glucose-casein mixture to starved rats. The prevention by these agents occurred without any change in the amount of diet consumed. When the injection of cyclic AMP and the refeeding of glucose-casein diet were initiated simultaneously, there was an inhibiton of G6PD induction depending upon the dose and frequency of cyclic AMP administration during the period of refeeding, while when cyclic AMP was given later than 12 h of the refeeding, the lag period for induction of this enzyme, there was no preventive effect. A glucose prefeeding was also found to counteract the inhibitory effect of cyclic AMP on G6PD induction by the subsequent glucose-casein refeeding. The present data together with the elimination of actinomycin D effect by the glucose prefeeding suggest that the inhibitory effect of cyclic AMP on the induction of G6PD dehydrogenase is exerted at the level of transcription.

Animals

Changes in fatty acid synthesis and lipogenic enzymes in adipose tissue from fasted and fasted-refed steers.

Controls of fatty acid synthesis in bovine adipose tissue were investigated. Six Brown Swiss steers were fasted for 8 days and then refed for 56 days. Biopsy samples of backfat adipose tissue were taken during the fasting and refeeding periods. Rates of acetate incorporation into fatty acids (FAS), activities of acetyl CoA carboxylase (CBX), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP:isocitrate dehydrogenase, and plasma free fatty acids (FFA) and plasma acetate were determined. FAS decreased 60% after 1 day of fasting and 99% after 8 days. FAS did not increase until day 3 of refeeding when energy intake was above maintenance, then returned to normal by 14 days. CBX followed a pattern similar to FAS, except its activity did rise above the control rate during refeeding. Plasma FFA increased 350% and acetate decreased 67% during fasting. After 4 days of refeeding, FFA returned to normal, and acetate increased to 156% of initial concentration, then returned to normal by 21 days. These data suggest that CBX limits FAS in adipose tissue of cattle.

Acetates

Stoppage of glycogenesis and "over-shoot" of induction of lipogenesis and its related enzyme activities in the liver of fasted-refed rats.

To elucidate the causes of changes of carbohydrate metabolic pathways, the time course of utilization of dietary [U-14C]sucrose and induction of enzyme activities in the livers of rats were investigated. Adult male rats of BHE strain were refed after a fast of 2 days. The nutritionally complete refeeding diet contained 60% sucrose as the only source of carbohydrate. [U-14C]Sucrose was included in the diet on either day 1 or day 2, or both of refeeding. During the first day of refeeding, the radioactivity was incorporated mainly into liver glycogen which rose to over 100 mg/g. During the second day, little 14C appeared in the liver glycogen, which decreased sharply while glucose-6-phosphatase activity increased. The glycogenic pathway thus appeared to be blocked. On the other hand, 14C incorporation in the liver fat was minimal during the first day, but was quite extensive during the second day of refeeding. The enhanced lipogenesis was accompanied by large increases of activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP-malic dehydrogenase. Results clearly indicate that the carbohydrate load in the liver of intact animals was initially metabolized by the glycogenic pathway. When glycogenesis stopped, carbohydrate was metabolized differently. The enhanced incorporation of [U-14C]sucrose into liver lipids indicates an increased formation of acetyl CoA and an accelerated formation and use of NADPH, probably from increasing dehydrogenase activities. Our data suggest that the blockage of synthesis of glycogen with the continuation of carbohydrate load was a primary cause in over-shooting induction of hepatic dehydrogenase activities and lipogenesis.

Adipose Tissue

Dietary fat-dependent changes in hepatic cholesterogenesis and the activity of 3-hydroxy-3-methylglutaryl-CoA reductase in fasted-refed rats.

Effects of various dietary fats on the activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and sterol and fatty acid synthesis from [1-14C]acetate and [2-14C]mevalonate were examined in the liver from fasted-refed rats. Rats fasted for 2 days were refed a fat-free diet or diets containing various fats (tricaprylin, trilaurin, trimyristin, tristearin, camellia oil, or safflower oil) at the 10% level for 1, 3, or 7 days. The activity of HMG-CoA reductase was restored to about one-half of the pre-fasting levels in all groups after refeeding for 1 day and increased to above the pre-fasting levels after 3 days, with the exception of safflower oil, the rise was especially noticeable when fat-free, tricaprylin, and tristearin diets were fed. After 7 days, the activity of HMG-CoA reductase, except for rats refed tristearin, was decreased to levels that were far below those observed after 1 day-refeeding. This was particularly marked with tricaprylin, trilaurin, and camellia oil. The response of sterogenesis resembled that of the reductase. Dietary fat-dependent modification of fatty acid synthesis from [1-14C]acetate was first demonstrated after 7 days. Hepatic esterified cholesterol tended to accumulate and the deposition was marked after 3 days of refeeding. However, fat-dependent alterations of this parameter were remarkable on day 7. The concentration of plasma cholesterol also showed dietary fat-dependent changes after refeeding. Dietary fats appear to play an important role not only in the regulation of hepatic HMG-CoA reductase and sterol synthesis, but also in the overall processes of cholesterol dynamics.

Animals

The regulation of erythropoiesis in protein-energy-malnutrition.

The erythropoietin (ESF) content of plasma and urine has been studied in children with protein-energy-malnutrition (PEM) living in the Kivu province at an altitude of 1467--2000 m. On admission, packed cell volume (PCV) was moderately reduced; after 2 months of refeeding PCV had increased but was still lower than in the controls. Plasma ESF was increased on admission and in patients refed for 2 months. The expected positive correlation between serum and urine ESF levels was found after refeeding but not on admission; the last finding could not be explained by the presence of erythropoiesis inhibiting factor(s) in the urine. In spite of the normal 2,3-DPG and P50 previously described in PEM in Kivu, the anaemia associated with this disease is not merely an adaptation to lowered oxygen consumption and there must be some disturbances in the responsiveness of bone marrow to ESF. The high ESF values observed after 2 months of refeeding confirm that the restoration of the red cell volume proceeds slowly.

Adolescent

Failure of short-term nutritional convalescence to reverse the adverse hemodynamic effects of protein-calorie malnutrition in dogs.

We previously reported that protein-calorie malnutrition (PCM) exerts adverse hemodynamic effects on left ventricular (LV) structure and function. In the present experiments, we tried to determine the duration of these adverse effects by inducing significant weight loss in matched beagle dogs followed by a short-term course of nutritional repletion. Following restitution of initial body weight, the animals were placed on total cardiopulmonary bypass and an isovolumetric LV preparation was established to determine baseline LV function compared with matched animals that remained normally-nourished, and with a third group in which the effects of PCM were not reversed. Decreases in LV compliance persisted following refeeding as did the decreases in the first derivative of LV pressure (LV dp/dt). Although animals re-fed ordinary diets following acute weight loss restored normal concentrations of myocardial glycogen, cardiac abnormalities persited for more than one month following refeeding. These results suggest that the adverse effects of semistarvation on LV functions cannot be completely reversed by short-term refeeding.

Animals

Effect of cholesterol-rich diet on the content of nicotinamide nucleotides, adenine nucleotides and acetyl-CoA in the liver, the vascular wall and the kidney of spontaneously hypertensive rats (SHR).

The liver content of NAD and of adenylic nucleotides of normally fed spontaneously hypertensive rats (SHR) is lower than in normotensive rats. The cholesterol-rich diet does not change the liver NAD level. However it decreases adenine nucleotides and increases the level of acetyl-CoA and of NADP. Normal refeeding after a long-term cholesterol-rich diet induces an increase in the low levels of the coenzymes (moth NAD and adenine nucleotides). The liver coenzyme changes caused by the cholesterol-rich diet and by the normal refeeding of SHR are opposite to those established in normotensive rats. Vascular wall nicotinamide coenzymes in SHR are lower than in ulistar rats. The vascular wall of SHR reacts to the cholesterol-rich diet by a rise in NAD, i.e. conversely to the reaction observed in the liver of SHR and vascular wall of normotensive rats. Normal refeeding induces a further increase in the content of coenzymes. These results show that the effect of cholesterol-rich diet on the coenzyme content in the SHR is opposite to that in normotensive rats. The renal redox-system NAD+-NAD-H is more sensitive to the cholesterol-rich diet than the liver one, and its coenzyme changes indicate a greater reduction state, a reaction pattern which is typical for renal hypoxia. The results suggest that the cholesterol-rich diet influences the metabolism of the liver, the kidney and the vascular wall in a different way and to a different degree. SHR have a specific type of reaction to this cholesterol-rich diet.

Acetyl Coenzyme A