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Biomedical subjects

S Margen

Publications and source records attributed to S Margen.

At least 37 records · Page 2Linked to original sources
PubMed1980

Sulphate, acid-base, and mineral balances of obese women during weight loss.

Four obese women, each at least 50% above their expected weight for height were maintained in the metabolic unit for 63 days on liquid formula diets of differing protein and calorie content. We made the following findings: 1) When 12 g protein nitrogen was consumed, 1 mEq of acid was excreted in the urine for every 2 mEq of urinary sulphate. 2) On a protein-free diet more acid was excreted in the urine than could be accounted for by oxidation of sulphur to the sulphate which was excreted in the urine. 3) Both increased consumption of protein and a restriction of dietary calories was associated with an increase of urinary acid. 4) Urinary sulphur excretion was closely correlated with nitrogen intake and urinary urea nitrogen excretion. However, on a protein-free diet the ratio of total nitrogen to sulphur in the urine was greater than when 12 g protein nitrogen was consumed. 5) There is some evidence that when total calorie intake was reduced at a level of 12 g protein nitrogen intake, the ratio of urinary urea nitrogen to urinary sulfur decreased. This suggests selective retention of some nonsulphur containing amino acids and/or selective oxidation of sulphur-containing amino acids. 6) In general, urinary calcium and magnesium excretions were depressed both with a decrease in protein consumption and a decrease in caloric intake. 7) The urinary excretions of calcium and magnesium showed a tendency to fall during the 63 days of the experiment. 8) The urinary and fecal phosphorus excretion remained constant during the various metabolic periods of the experiment.

Acid-Base Equilibrium↗
PubMed1980

Wine versus ethanol in human nutrition. IV. Zinc balance.

Six healthy young men participated in a metabolic balance study to assess the effects of wine versus ethanol on absorption of various elements. Zinc data are reported here. During each of four 18-day experimental periods, the subjects were fed a controlled diet plus 1 liter/day of one of the following test beverages, administered in random order: Zinfandel wine, dealcoholized Zinfandel wine, an aqueous ethanol solution, or deionized water. Urinary zinc was significantly greater during wine and ethanol administration than during administration of the nonalcoholic beverages, suggesting that alcohol may affect the metabolism or renal conservation mechanism for zinc. The possibility of muscle catabolism due to alcohol ingestion is discussed. There was increased absorption and, perhaps, also, decreased endogenous secretion of zinc during the wine and dealcoholized wine periods, as compared with ethanol and deionized water. That presumably was due to the nonalcoholic constiuents of wine. Analysis of zinc in whole sweat after strenous exercise revealed that a considerable amount of this ion can be lost under conditions of excessive sweating.

Absorption↗
PubMed1979

Use of a spectrophotometer for radiographic photodensitometry of bone.

A conventional spectrophotometer was used to do radiographic photodensitometry of bone mass. An experiment to produce osteoporosis in guinea pigs required quantification of changes in bone mass. Lack of a densitometer necessitated finding another method for quantification. The method developed involved using industrial film in a closed X-ray system. Optical density of X-rays was then read in a spectrophotometer at nine femur locations. Highly significant correlations between optical density and femur calcium content and femur dry weight per millimeter were obtained. Histological sections from an animal with low optical density measurements confirmed bone loss by showing decreased cortical width and loss of trabecular bone. In addition to using readily available equipment, this method offers the advantage of being able to detect bone loss in specific areas of the bones. In addition, bones are left intact and can be used for other purposes.

Absorptiometry, Photon↗
PubMed1979

Polyethylene glycol as a quantitative fecal marker in human nutrition experiments.

Data are summarized from five experiments in which polyethylene glycol (PEG) was fed to 51 subjects as a quantitative fecal marker. In three experiments PEG was fed continuously for 35 to 106 days. Preexperimental diet was assumed to have been completely excreted when the ratio of fecal PEG to fecal dry solids became constant. This took more than 7 days to occur in 50% of the subjects. Fecal recovery of PEG averaged only 93% of that consumed. PEG was a valid fecal marker for nitrogen, calcium, magnesium, iron, and zinc, but was less valid for sodium. In one experiment where PEG and chromic oxide (Cr2O3) were fed simultaneously, PEG was excreted faster on average than Cr2O3. In most subjects, small amounts of Cr2O3 were excreted sporadically for 42 days after Cr2O3 feeding had ceased. Inclusion of quantitative fecal markers permitted identification of the time when preexperimental diet had been completely eliminated, subjects who showed marked pooling of intestinal contents, and changes in the amount of fecal dry solids. However, an average fecal recovery of only 93% of the PEG or Cr2O3 consumed suggests that further work is needed before the recovery of either of these markers can be used with confidence for the correction of nutrient balance data.

Calcium↗
PubMed1979

Protein-induced hypercalciuria: a longer term study.

Urine calcium excretion is known to be directly correlated with the level of dietary protein intake. In this experiment we examined the persistence of the hypercalciuria induced by the consumption of high protein diets, and the mechanism of the calciuric response. In a 95-day metabolic study, each of six adult male subjects received formula diets supplying 12 g nitrogen or 36 g nitrogen, and approximately 1400 mg calcium per day. Urine calcium increased rapidly and significantly from an average of 191 mg/day on the 12 g nitrogen diet to 277 mg/day on the 36 g nitrogen diet. There was no significant difference in the apparent absorption of calcium, so that overall calcium balance was -37 mg/day on the 12 g nitrogen diet, and significantly lower at -137 mg/day in subjects consuming the high protein diet. Levels of urinary hydroxyproline, serum insulin, and parathyroid hormone were not significantly increased by high intakes of protein. A decrease in the fractional reabsorption of calcium by the kidney seems to be the most likely cause of the protein-induced hypercalciuria. The consumption of high calcium diets is unlikely to prevent the negative calcium balance and probable bone loss induced by the consumption of high protein diets.

Adult↗
PubMed1979

Wine versus ethanol in human nutrition. II. Fluid, sodium, and potassium balance.

Six healthy males were studied under metabolic unit conditions to determine the effects of wine vs ethanol on the absorption of various elements. Fluid, sodium, and potassium data are reported here. The following test beverages in the amount of 1 liter/day were administered in random order to each of the subjects during four 18-day experimental periods: Zinfandel wine (9.3% w/v alcohol); dealcoholized Zinfandel wine; pure ethanol (9.3% w/v aqueous alcohol solution); and deionized water. A strictly controlled isocaloric formula diet was given with the test beverage in four equal feedings over a 12-hr period. No diuretic effect of alcohol was detected in any of the subjects. Urinary sodium was significantly less during the dealcoholized wine period than during the ethanol and water periods. Urinary potassium was significantly greater during ethanol administration as compared with the other test beverages. Fecal and serum sodium and potassium were essentially unchanged throughout the study.

Adult↗
PubMed1979

Wine versus ethanol in human nutrition. III. Calcium, phosphorous, and magnesium balance.

A metabolic balance study was performed to determine the effects of wine vs ethanol on absorption of various elements. Calcium, phosphorus, and magnesium data are reported here. The study was divided into four 18-day experimental periods during which six healthy males were given, in random order, 1 liter/day of one of the following test beverages: Zinfandel wine (9.3% w/v alcohol); delacholized Zinfandel wine; pure ethanol (9.3% w/v aqueous solution); or deionized water. The test beverages were administered along with a controlled isocaloric diet in four equal feedings over a 12-hr period. Each man served as his own control. Urinary calcium and magnesium did not change appreciably during the course of the study. Urinary phosphorous, however, was significantly greater during wine and ethanol administration, suggesting that alcohol may affect the metabolism or renal tubular reabsorption of this element. Despite considerable individual variation, the data showed that wine and dealcoholized wine enhanced absorption of calcium, phosphorus, and magnesium. This apparently was due to an effect of one or more of the many congeners present in wine and absent in a calorically equivalent amount of pure ethanol. The natural acidity of wine also may have played a role in creating a more favorable intraluminal environment for absorption. There was no significant difference between experimental periods in serum calcium, phosphorus, and magnesium.

Adult↗
PubMed1979

Lactation and pregnancy in Iran. III. Hormonal factors.

Lactation failure is common in urban areas of industrially developing countries, but little is known about its epidemiology and causality. The study reported here was undertaken to investigate the serum levels of some hormones other than prolactin that have been shown in animal studies to play a role in lactation, and to examine their relationship to adequacy of lactation and to nutritional and socioeconomic status in urban Iranian women. Serum levels of placental lactogen, growth hormone, cortisol, and thyroid hormones were measured under standard conditions in two groups of pregnant women from low and low middle socioeconomic areas of Teheran, 1 or 2 weeks before parturition and the latter three hormones again in the 3rd month postpartum. Significant differences were found in the biochemical parameters between socioeconomic groups. Hemoglobin and serum albumin values were lower and all the globulin fractions (except alpha 2 globulin during pregnancy), growth hormone and cortisol were higher in the low than the middle socioeconomic subjects, both during pregnancy and postpartum. The discrepancies between the socioeconomic groups were greater postpartum. Growth hormone level was significantly lower in subjects with adequate lactation than inadequate or ceased, and cortisol values show the same trend. No correlations were found between the measured parameters of nutritional status nor free thyroxine values and lactation adequacy. In view of the role of growth hormone and cortisol in stress and malnutrition and some evidence of a reciprocal relationship between growth hormone and prolactin, these hormones may be a link in the chain between the urban environment, malnutrition and lactation failure.

Blood Proteins↗
PubMed1979

Integumentary loss of calcium.

Integumentary calcium loss was studied in 16 healthy young men. The daily loss by the 16 ambulatory but relatively sedentary young men in 52 determinations of 6-day periods each was 8.7 +/- 1.9 mg/m2 per day (average 15.8 mg/man per day). The amount lost was not influenced by calcium intake (0.1 to 2.3 g/day). In contrast to urinary calcium excretion, which is directly related to protein intake, there was no significant change in integumentary calcium loss with varying protein intakes (1 to 96 g nitrogen per day). No compensatory relationship between urinary and integumentary calcium excretion was noted. During strenuous exercise calcium loss increased to an average of 25 mg in 40 min. There was no compensatory decrease in urinary excretion on the day of strenuous exercise. It was also noted that integumentary calcium loss was not affected by general calcium balance.

Adult↗
PubMed1979

Nitrogen balance studies in humans: long-term effect of high nitrogen intake on nitrogen accretion.

Six healthy young adult male participants were confined to a metabolic ward for 105 days. Two nutritionally adequate purified diets providing 12 and 36 g of nitrogen per day were randomized in two metabolic periods of approximately 50 days each. The objective of this study was to verify whether or not positive nitrogen balance is a concomitant of increased nitrogen intake under the most rigorously controlled conditions, and if so, whether adaptation could occur if the experiment was conducted for sufficiently long periods of time. The mean nitrogen balance was slightly negative for most participants when fed the 12 g N diet. However, individual variability was so large that statistically all the participants can be considered in balance. In view of this, we agree with other investigators who have suggested that balance should be considered as an area which takes into account variabilities such as intake, output and biological factors. On the 36 g N diet, all the participants exhibited strong positive balances, about 1.6 g/day, which were not as high as reported by other investigators but which persisted for as long as they were fed this diet. This positive balance could not seem to be explained on the basis of methodological errors or to any unmeasured nitrogen losses. There was no significant trend towards adaptation as claimed.

Adaptation, Physiological↗
PubMed1979

Effect of glucocorticoids and zinc deficiency on femur and liver zinc in rats.

Male weanling rats were fed diets containing less than 1, 3, 6 oor 13 ppm zinc or stock rat diet for 3 weeks. Each dietary group was subdivided into a control group and a prednisolone-treated group (5 mg pred/kg body weight). Femur and liver zinc contents were determined by flame atomic absorption spectrophotometry. Prednisolone caused growth retardation at all levels of dietary zinc. A marked increase was seen in femur zinc content of prednisolone-treated rats fed zinc-deficient diets. No such increase was seen in rats fed diets adequate in zinc. No significant change was seen in liver zinc content of zinc-deficient rats due to prednisolone. By comparing femur zinc in rats fed zinc-deficient diets with femur zinc in weanling rats, it appears that prednisolone causes an increase in femur zinc in rats fed deficient diets by (a) preventing bone resorption, and (b) increasing femur uptake of dietary zinc. Because the effects of glucocorticoids in rats appear to differ from effects in man, similar studies in other species are recommended.

Animals↗
PubMed1979

Amino acids in human blood plasma after single meals of meat, oil, sucrose and whiskey.

Six healthy men (21 to 38 years; 58 to 80 kg) consumed an adequate diet in a metabolism unit. At 4-day intervals they ingested test meals and venous blood was drawn before and after ingestion at intervals for 8 hours. Test meals were 100, 200, and 300 g of cooked lean meat and quantities of corn oil, sucrose, and whiskey isoenergetic with 200 g of meat. Plasma was analyzed for 20 amino acids. Mean totals of amino acids (micromoles per liter) were maximally elevated at 1 or 2 hours post cibum for all meals and remained above fasting values at 4 hours, with one exception (glucose meal). At 8 hours they were all below fasting values with one exception (whiskey meal). Individual responses varied so much that mean values are misleading. One subject responded well to ingestion of 100 or 200 g of meat but failed to respond to 300 g of meat, oil, or sucrose. Another subject responded well to oil and sucrose, but failed to respond to 100 or 200 g of meat. Mean total fasting amino acid values for all subjects were relatively constant but values for individual subjects ranged from 16% above to 18% below their own fasting means. Ingestion of whiskey invariably resulted in a significant decline in molar ratios for histidine and a significant increase for threonine.

Adult↗
PubMed1979

Effect of glucocorticoids and calcium intake on bone density and bone, liver and plasma minerals in guinea pigs.

The purpose of this study was to see what effect glucocorticoids would have on bone density and mineral distribution in guinea pigs. Adult female guinea pigs were given prednisolone, a synthetic analogue of cortisol, for up to 24 weeks. Bone density and bone, liver and plasma levels of zinc, copper, iron, manganese, chromium, magnesium and calcium were studied in these animals. In one study, the effect of menopause was simulated by using ovariectomy. In another study, dietary calcium was varied to investigate its effect with glucocorticoids. Animals treated with 1 mg prednisolone/kg body weight showed increased femur density compared with controls, but no changes in tissue mineral concentrations. Animals fed 100 mg prednisolone/kg body weight experienced decreased femur density. Differences in effects were not observed between ovariectomized and intact animals. Bone loss was greatest in animals fed the cereal-based closed-formula diet and least in animals fed the low-calcium diet. Changes in mineral content of femurs observed in animals which lost bone mass were increased iron concentration and decreased magnesium concentration. Total liver stores of zinc and magnesium increased. Liver copper increased in concentration per gram as well as in total content. Liver concentration of manganese decreased. Plasma changes in animals fed the high level of drug were decreased iron and calcium, and increased copper. Hemoglobin and hematocrit increased with increasing drug levels. It is suggested that glucocorticoids have marked effects on mineral metabolism which may be related to the bone loss and that these effects may be modified by dietary changes.

Animals↗
PubMed1979

Behavioral epidemiology of food additives.

Behavioral toxicology in the natural environment can be considered a special branch of epidemiology. Behavioral epidemiology, because it typically relies on complex functional criteria, faces all of the problems of behavior measurement posed by uncontrollable variation, and amplified even further by chemical exposure. Many such issues arose in a study of behavioral responses to artificial food colors in children. Difficulties in employing Applied Behavioral Analysis in such a context run the gamut from selection of retrospective criteria to appropriate statistical models.

Child↗
PubMed1978

Lactation and pregnancy in Iran. I. Social and economic aspects.

Adequacy of lactation was assessed in Teheran women of low (LSE) and lower-middle (MSE) socioeconomic status in the third month postpartum, as part of a study linking nutrition, hormonal status, and lactation. Methods of assessment of nutritional adequacy are discussed. Characteristics of the socioeconomic groups, infant mortality, food beliefs related to lactation, and supplemental feeding practices are described. Of the LSE mothers 15 to 30% and of the MSE mothers 40 to 55% had a fully adequate milk supply in the third month. Substitutes used and affordable by the LSE were nutritionally inadequate. LSE mothers were traditional in their food beliefs. MSE mothers demonstrate the influence of scientific nutrition knowledge. The low percentage of lactation adequacy even in the MSE indicates that other social or health factors associated with urban living conditions may be just as important as economic and nutritional factors in lactation failure.

Energy Intake↗