Studies on zinc deficiency: changes in trace elements and enzyme activities in tissues of zinc-deficient rats.

Zinc content of testes, bones, esophagus, kidneys, and muscles was decreased, whereas iron content was increased in the testes of zinc-deficient rats compared to restrictedly fed control rats. Histochemical enzyme determinations revealed reduced activities of certain enzymes in the testes, bones, esophagus, and kidneys. In the testes, lactic dehydrogenase (LDH), malic dehydrogenase (MDH), alcohol dehydrogenase (ADH), and NADH diaphorase; in the bones, LDH, MDH, ADH, and alkaline phosphatase; in the esophagus, MDH, ADH, and NADH diaphorase; and in the kidneys, MDH and alkaline phosphatase were decreased in zinc-deficient rats compared to restrictedly fed controls. Succinic dehydrogenase (SDH) revealed no significant changes under the conditions of our experiments in various groups of rats that were investigated. In a "repleted" group of rats, content of zinc in testes and bones increased significantly, compared to the deficient group. The iron content of the testes decreased after repletion with zinc. In the testes, bones, esophagus, and kidneys, the activities of various enzymes increased after repletion with zinc. Inasmuch as the major manifestations of zinc deficiency syndrome in the rat include growth retardation, testicular atrophy, and esophageal parakeratosis, our results suggest that the content of zinc in the above tissues most likely controls the physiological processes through the formation of zinc-dependent enzymes.

Effect of oral contraceptive agents on nutrients: I. Minerals.

The epidemiological aspects of oral contraceptive agents on nutrient metabolism were studied in a large population of women. Incidence of clinical abnormalities, related to malnutrition, were more frequently observed in the lower (B) as compared to the higher (A) socioeconomic groups. In the A groups some clinical signs were more common in the nonsupplemented groups of subjects. In general, the intake of oral contraceptive agent subjects for calories, protein, calcium, magnesium, iron, copper and zinc did not differ from the controls. The intake of the above nutrients in group A subjects were higher than those of group B except for calories. The subjects who took supplements had higher intakes of calcium, iron, magnesium and copper. No effect of oral contraceptive agents was seen on hemoglobin, hematocrit and erythrocyte count. Serum iron was increased due to "Norinyl." Total iron binding capacity was increased as a result of oral contraceptive agent administration. Total iron binding capacity values were higher in group B as compared to group A and in the nonsupplemented as compared to the supplemented groups. Plasma copper was increased and plasma zinc was decreased as a result of oral contraceptive agent administration. An increase in erythrocyte zinc was observed due to "Norinyl." No effect of oral contraceptive agents on plasma calcium, magnesium and erythrocyte magnesium was observed. Although no effect of oral contraceptive agents on plasma total protein was found, serum albumin was decreased.

Effect of oral contraceptive agents on nutrients: II. Vitamins.

Clinical, biochemical and nutritional data were collected from a large population of women using oral contraceptive agents. Higher incidence of abnormal clinical signs related to malnutrition were observed in the lower (B) as compared to the higher (A) socioeconomic groups, and also in the nonsupplemented groups as compared to the supplemented groups in the B subjects. As a rule the intake of oral contraceptive agent subjects of vitamin A, C, B6 and folic acid did not differ from that of the controls As expected, subjects from the supplemented groups had higher intake of vitamin A, C, B6, thiamin, riboflavin and folic acid, and A groups had higher intake of vitamin C, B6, riboflavin and folic acid. Increased plasma vitamin A and decreased carotene levels were observed in oral contraceptive agent users. In general oral contraceptive agents had little or no effect on plasma ascorbic acid. Urinary excretion of both thiamin and riboflavin in subjects using oral contraceptive agents were lower in A groups. Erythrocyte folate and plasma pyridoxal phosphate was decreased in A groups due to oral contraceptive agents. Subjects who took supplements had higher levels of plasma vitamin A, ascorbic acid and folate. But urinary thiamin and riboflavin were higher only in group A subjects who took supplements.

PIP: 18-45 year old women were tested to determine if the use of oral contraceptive agents (OCAs) affects the metabolism of vitamins. 4 different hormonal conditions and 2 socioeconomic levels in 8 groups were considered. Some of each socioeconomic level had taken Norinyl (1 mg norethisterone and 50 mcg mestranol) for 3 months or more. Others had used Ovral (.5 mg norgestrel and 5 mcg ethinyl estradiol) for equal periods. There were some in each group who had resumed use of OCAs during lactation within 5 weeks after pregnancy. Vitamins and mineral supplements were given to groups in each socioeconomic classification. They had a higher intake of Vitamins-A, C, thiamin, riboflavin, and folic acid. Incidence of clinical sings of malnutrition, such as dry skin, easily pluckable hair, angular lesions of the mouth, dental caries, bleeding gums, glossitis, and scaling of the skin, were significantly more frequently observed in the lower socioeconomic groups, and especially in nonsupplemented groups of women taking OCAs than in others. OCA administration increased plasma Vitamin-A levels but no socioeconomic effect was found. Plasma carotene levels were decreased by OCA therapy, but less so in the higher socioeconomic subjects. Plasma ascorbate was not affected by OCA use. Urinary excretion of thiamin annd riboflavin was decreased in subjects using OCAs. Erythrocyte folate and plasma pyridoxal phosphate (PLP) were also decreased. Results show a definite lowering effect of OCAs on red cell folate in subjects in the upper socioeconomic levels. There may also be a depletion of body stores of folic acid. It has been suggested that women who become pregnant soon after discontinuing OCA therapy have a high chance of developing folic acid deficiency during pregnancy. The lower socioeconomic group may be marginally deficient in folic acid. Similar results were obtained with thiamin and riboflavin. Changes due to OCA use with respect to thiamin, riboflavin, folate, and PLP were seen mainly in subjects in the upper lower socioeconomic groups may have prevented detection of smaller similar alterations due to OCA use.

Effect of a chronic tryptophan dietary deficiency on the rat's sleep-wake cycle.

The sleep-wake cycle of 12 tryptophan dietary deficient rats and their non-deficient paired controls were observed for a 8:00 a.m. to 8:00 p.m. period. EEG, EMG and body activity were continuously monitored on polygraphic recordings throughout the 12 hr observation period. The results indicate no significant difference between the tryptophan deficient and sufficient animals in time spent awake, slow-wave or parodoxical sleep. There was a non-significant trend among the tryptophan deficient animals to be less active and spend more time in both slow-wave and paradoxical sleep, which is in contrast to an expected insomnia effect. The results do not support the suggested relationship between reduced serotonin levels and the occurrence of insomnia, questioning the serotonergic theory of sleep.

Mechanism of zinc homeostasis.

Homeostatic equilibrium of a nutrient is characteristic of a healthy body. For zinc, phytate has been shown to alter that equilibrium in several monogastric species including man. The pancreas is an important organ in the maintenance of zinc homeostasis. Elevated calcium has been shown to be a synergistic agent in affecting the rate of onset and rate of homeostatic change. In the studies described, rats were depleted of zinc to differing extents, zinc was injected intraperitoneally to label the endogenous zinc pool. Phytate- and nonphytate-containing protein diets were fed and feces were collected. Feces were counted for radioactivity. The ratios of radioactivity (phytate:nonphytate) indicated that the major effect of phytate was on the endogenous secreted pool. Evidence is included to indicate that two, pancreatic labile pools of zinc are secreted, one is stable complexes not affected by phytate and two, a labile pool of zinc readily available for complexation. A mathematical model is included that fits all nutritional models for zinc homeostasis.

Phytate content of foods: effect on dietary zinc bioavailability.

The phytate content of several foods is presented. Published zinc values were used to calculate phytate:zinc molar ratios. These ratios can be used to estimate the relative risk of having an inadequate intake of zinc. They may be used in planning menus to select the combination of foods that will supply the most available zinc to the daily diet. On the basis of animal experiments to date, a daily phytate:zinc molar ratio of 10 or less is thought to be acceptable in providing adequate dietary zinc, and daily ratios consistently above 20 may jeopardize zinc status. Many factors other than the daily dietary phytate:zinc molar ratio influence zinc nutriture, but the ratio concept is a tool which may contribute to a more accurate assessment of zinc status.

Proposed phytic acid standard including a method for its analysis.

A method is described that accurately and rapidly quantifies the free and total phosphorous content of a commercially available, purified, phytic acid preparation. This allows its use as a standard for phytic acid determinations in foods. The method involves a wet ashing step followed by phosphorous measurement with a 1-amino-2-naphthol-4-sulfonic acid-molybdate reagent in a microplate reader at 660 nm. The procedure can be performed in 3 h with as little as 50 mg sample.

Anion-exchange method for determination of phytate in foods: collaborative study.

Phytate, a naturally occurring organic compound found in plant seeds, roots, and tubers, was determined in a collaborative study using a modified anion-exchange method. Seven samples (peanut flour, oats, rice, isolated soybean protein, a vegetarian diet composite, wheat bran, and whole wheat bread), supplied as blind duplicate samples, were analyzed in triplicate by 7 collaborators. Phytate concentrations in the samples ranged from 2.38 to 46.70 mg/g. Relative standard deviations (RSD = CV) for repeatability ranged from 2.5 to 10.1%, and for reproducibility, from 4.5 to 11.0%. The method has been adopted official first action.

Nutritional agents which affect metabolic zinc status.

As the number of factors which affect zinc absorption and homeostasis increase, it becomes more apparent that the relative zinc status of the population cannot be estimated from the analyzed zinc content of foods. The environment of the small intestine at the time of absorption can only be estimated from the diet fed. Even then since both endogenous and exogenous factors determine the zinc absorbed, the precision of these estimations should allow for large individual variation.

Effect of washing procedures on trace-element content of hair.

A pooled sample of hair was divided and portions prepared for analysis by three washing procedures, to evaluate the effect of washing procedure on the subsequent trace-element (Zn, Cu, Mg) content. The methods selected were a detergent wash, a hexane-ethanol wash, and an acetone-ether-detergent wash. For all elements, there was a significant difference among the results after these wash procedures. Magnesium content of hair was most affected by washing, containing less than half of the magnesium of the unwashed hair. The detergent wash removed the most zinc and magnesium; the acetone-ether-detergent wash removed the most copper. Our results indicate that the trace-element analysis of hair is sensitive to the preparation technique and therefore is an unreliable source of information about trace-element status.

Gonadal function abnormalities in sickle cell anemia. Studies in adult male patients.

Thirty-two adult patients with sickle cell anemia were evaluated endocrinologically. Secondary sex characteristics were abnormal in 29, and eunuchoidal skeletal proportions were present in all except one. The age at which different stages of pubic hair growth were attained in these patients was delayed in comparison to normals (P less than 0.005). Hormonal assays were carried out in 14 patients. Basal serum testosterone, dihydrotestosterone, and androstenedione values were lower (P less than 0.02) in patients than controls. Serum LH and FSH levels before and after stimulation with gonadotropin-releasing hormone were consistent with primary testicular failure. Erythrocyte and hair zinc concentrations were significantly decreased, and there was positive correlation between erythrocyte zinc and serum testosterone (r = 0.61, P less than 0.01) in sickle cell anemia. Our study shows that androgen deficiency in this disease is a result of primary rather than secondary hypogondadism. Further studies are required to establish the role of zinc in the pathogenesis of testicular failure in sickle cell anemia.