Search PubMed⌕ Search

Biomedical subjects

H H Sandstead

Publications and source records attributed to H H Sandstead.

At least 73 records · Page 4Linked to original sources
PubMed1984

Maternal zinc, iron, folic acid, and protein nutriture and outcome of human pregnancy.

Four hundred fifty women were observed during pregnancy and postpartum. Forty-three variables including 12 laboratory indices of maternal nutrient status were assessed. Of the variance in fetal weight and head circumference 9.9 and 8.1%, respectively, were predictable by polynomial stepwise regression of laboratory indices of maternal nutriture. Maternal plasma zinc levels were inversely correlated with fetal weight. The occurrence of pregnancy complications in the highest and lowest quartiles of maternal plasma zinc, albumin, iron, and folic acid were compared. Using data only from the initial blood samples for which the trimester was identified precisely (n = 394), a significant association was found between the total occurrence of fetomaternal complications and zinc and albumin levels in the lowest quartile (zinc, p less than 0.02; albumin, p less than 0.02). Low zinc or low albumin were also associated with the specific complications of fetal distress (zinc, p less than 0.002; albumin p less than 0.002). High plasma folate was also associated with the total occurrence of complications (p less than 0.008) and with fetal distress (p less than 0.002). When all data (n = 713) including repeat blood samples and data from 56 mothers in whom the trimester could not be verified precisely were evaluated, associations between other complications and lowest quartile zinc and albumin and highest quartile folate were identified. Discriminant analysis of data from the initial blood samples revealed that plasma zinc was a discriminator for fetomaternal complications only in women in the lowest quartile for plasma zinc.

Adult↗
PubMed1984

Changes in plasma zinc content after exercise in men fed a low-zinc diet.

For 30 days five healthy men aged 23-57 yr consumed a diet adequate in zinc (8.6 mg/day); they ate a low-zinc diet (3.6 mg/day) for the next 120 days and then received a zinc-supplemented (33.6 mg/day) diet for 30 days. Copper intake was constant at 1.8 mg/day. Aerobic capacity was determined periodically during each diet period. Relative zinc balance (% of control) declined during depletion (r = -0.28, P less than 0.009). Pre- and postexercise zinc concentrations decreased when dietary zinc was restricted (r = -0.61, P less than 0.0001 and r = -0.78, P less than 0.0001) and increased with supplementation (r = 0.61, P less than 0.008 and r = 0.76, P less than 0.0003, respectively). Both plasma zinc and hematocrit increased (P less than 0.01) after maximal exercise. To minimize the effect of hemoconcentration during exercise, the van Beaumont quotient (J. Appl. Physiol. 34: 102-106, 1973) was calculated using pre- and postexercise hematocrit and plasma zinc. The initial quotient of 1.8 +/- 1.8% (mean +/- SE) declined (P less than 0.05) to -7.4 +/- 2.3% during depletion. With zinc repletion, the quotient increased to 6.9 +/- 3.6%, which was greater (P less than 0.05) than the quotient in depletion but similar to the initial quotient. The quotient was a strong predictor (r = 0.71, P less than 0.0005) of the change in relative zinc balance during zinc depletion. In contrast, no changes were found in plasma copper content. These data suggest that zinc mobilization from tissues is impaired during zinc depletion, and they validate the use of the van Beaumont quotient as an index of change in body zinc stores.

Adult↗
PubMed1984

The effects of zinc deficiency on developing photoreceptors in the rat retina: a scanning microscopic study.

A study was undertaken to observe the effects of dietary zinc deficiency on the topographical morphology of developing photoreceptor (rod) cells in the sensory retina of the rat. Observations were made by means of scanning electron microscopy (SEM). Pups were utilized from three groups including (1) zinc deficient (2) pair-fed controls and (3) ad libitum controls. Animals ranged in age from birth to twenty days. Femur zinc levels were measured by flame atomic absorption spectrophotometry. A statistically significant increase in the number of photoreceptor cells continued through the 6th day, however, no morphological differences were noted among cells during the first 13 days. By day 14, outer segments appeared more elongated in ad libitum control tissues. No differences in outer segment length were apparent by day 20.

Age Factors↗
PubMed1983

Alterations in the postnatal development of the cerebellar cortex due to zinc deficiency. I. Impaired acquisition of granule cells.

The effects of zinc deficiency on cerebellar development were investigated in suckling rats. In 21-day-old zinc-deficient rats the cerebellum as well as the whole brain was reduced in size. The cerebellar cortex was underdeveloped and showed a persistence of the external granule cell layer, a reduction in the thickness of molecular layer and a decrease in the area of the internal granule cell layer. Lobular variations were present. Along the posterior superior fissure there was approximately a 60% reduction in the number of granule cells and in the number of granule cells per Purkinje cell. It was suggested that the reduction in the number of granule cells was predominantly the result of impaired cell proliferation in the external granule cell layer. Comparisons with undernourished, pair-fed pups indicated that the effects of zinc deficiency could not be mediated totally through the reduced food consumption experienced by zinc deficient dams.

Animals↗
PubMed1983

Learning and memory impairment in adult rats due to severe zinc deficiency during lactation.

In a series of three experiments, adult rats who suffered severe zinc deficiency and/or undernutrition during lactation were tested in a 17-arm radial maze for working memory, reference memory, forgetting and learning. In Experiment 1, eight out of 17 arms were baited. The zinc deficient (ZD) and undernourished (PF) rats revealed a learning deficit when compared to adequately nourished rats (AL). ZD rats also appeared to display a loss of working memory. No evidence of loss of reference memory was observed among any of the groups. A reverse learning procedure was used in Experiment 2 to test the same rats used in Experiment 1. ZD rats were significantly inferior in performance of the reverse learning task compared to the AL and PF rats. No significant differences in performance were noted between the AL and PF rats. Although all groups displayed forgetfulness from Experiment 1 to Experiment 2, no significant differences in forgetfulness were evidenced among the groups. In Experiment 3, all 17 arms were baited. The ZD rats displayed a significant working memory deficit as compared to the AL and PF rats. No significant differences in working memory between the AL and PF rats occurred. The possibility that the differences in performance were due to differences in food motivation or attention was considered and rejected. It was concluded that ZD rats experienced a severe learning deficit and some working memory deficit while the PF rats experienced a mild learning deficit as compared to the AL rats.

Animals↗
PubMed1983

Effect of a moderate increase in dietary protein on the retention and excretion of Ca, Cu, Fe, Mg, P, and Zn by adult males.

Mineral utilization was studied by metabolic balance techniques in 10 healthy male volunteers fed diets containing 65 and 94 g protein. Both diets contained approximately 650 mg calcium, 1 mg copper, 16 mg iron, 250 mg magnesium 1000 mg phosphorus, and 7 mg zinc. The diet consisted of conventional foods; the additional 29 g protein was egg white protein mixed into a beverage and fed twice per day. Plasma mineral levels were not affected by the increase in dietary protein. When the diet provided 94 g of protein, urinary calcium and zinc were slightly, but significantly, increased by an average of 35 mg (p less than 0.05) and 0.15 mg (p less than 0.001), respectively. Apparent mineral absorption and balance were unchanged by this modest increase in dietary protein.

Absorption↗
PubMed1983

Maximal oxygen consumption as related to magnesium, copper, and zinc nutriture.

Forty-four healthy male university athletes and 20 untrained men underwent maximal treadmill exercise testing to determine the relationship between maximal oxygen consumption and various measurements of elemental nutriture. Hb and mean plasma and erythrocyte concentrations of magnesium, copper, and zinc were within established norms for both groups after a 12-h fast. Mean plasma copper concentration was significantly (p less than 0.01) higher in the athletes (90 +/- 14.3 versus 81 +/- 8.0 micrograms/dl). Average maximal oxygen consumption also was significantly (p less than 0.001) higher in the athletes [4.5 +/- 0.5 versus 3.3 +/- 0.6 L/min and 55.5 +/- 7.1 versus 47.0 +/- 6.0 ml/(kg x min)]. Plasma magnesium was significantly correlated (r = 0.46; p less than 0.002) with maximal oxygen consumption, ml/(kg x min), among the athletes. This relationship persisted when the effect of Hb concentration was removed by covariance analysis (p less than 0.005). Only a weak association (r = -0.32; p = 0.17) was found between oxygen consumption and plasma magnesium in the untrained men. We hypothesize that ionic magnesium may facilitate oxygen delivery to working muscle tissue in trained subjects.

Adult↗
PubMed1983

Folate status of adult males living in a metabolic unit: possible relationships with iron nutriture.

Folate and iron status was monitored at monthly intervals in 40 adult males who were living in a metabolic unit for 2 to 8 months and consuming diets containing 150 to 250 micrograms of folate per day. There were significant (p less than 0.02) declines in hematocrit, serum folate, and serum ferritin. Men who participated in studies for 6 months or more or those with initial serum folate levels more than 10.5 ng/ml and erythrocyte folate levels more than 481 ng/ml also exhibited a highly significant (p less than 0.001) decline in red blood cell folate. Men with erythrocyte folate below 480 ng/ml or serum folate below 10 ng/ml and who participated in the studies for less than 5 months showed little or no change in folate status. The findings may reflect adjustments in body folate to reflect dietary intakes. Also a folate intake of 200 +/- 68 micrograms/day appeared to be adequate for maintenance of folate stores in adult males. A correlation between iron stores and folate status was also observed. However, this relationship may be coincidental.

Adult↗
PubMed1983

Effect of dietary zinc on whole body surface loss of zinc: impact on estimation of zinc retention by balance method.

Whole-body sweat losses of zinc were studied in men during three separate studies on the effects of marginal intake of zinc. Zinc lost via the sweat appeared to be directly related to dietary zinc intake. Whole body zinc losses of an average of 0.49 mg/day were observed in the men during the control period when zinc intakes averaged 8.3 mg/day. On the other hand, when zinc intakes were 3.6 mg/day, whole body surface zinc losses were substantially lower, averaging 0.24 mg/day in two of the studies and slightly lower than control values in the third study. A loss of 0.62 mg of zinc/day was observed when 33.7 mg of zinc was fed. These losses reduced apparent balances by 12 to 84% and need to be considered when evaluating zinc retention. When men were eating the diets with marginal levels of zinc (3.6 mg/day), zinc losses in sweat gradually declined with time. This suggested a homeostatic mechanism to conserve zinc during periods of depletion.

Adult↗
PubMed1983

Effect of zinc deficiency on appetite and free amino acid concentrations in rat brain.

Brain amino acids were measured in 30-day-old male Long-Evans rats subsequent to feeding a 20% egg white biotin-enriched zinc-deficient diet for 9 days. The zinc-deficient (ZD) group was given distilled deionized water. Zinc-supplemented control groups included pair-fed (PF), ad libitum-fed (AL) and ad libitum-fed, overnight fasted (OF) animals. Brain tyrosine concentrations and related amino acid ratios tended to be higher when food was consumed in all groups. Brain tryptophan concentrations and a brain amino acid ratio (glycine + serine + glutamine + taurine:leucine + isoleucine + valine + methionine) were not related to food intake in ZD rats in contrast to zinc-adequate controls. Also the brain ratio of tryptophan to the sum of large neutral amino acids minus tryptophan was not related to food intake in the ZD and AL-OF groups in contrast to the PF group. There were some differences in brain amino acid concentrations between ZD rats and the control groups; however, the pattern of the brain amino acids in ZD rats did not suggest that food intake was directly influenced by them.

Amino Acids↗
PubMed1983

Severe zinc deficiency: effects on the distribution of nine elements (potassium, phosphorus, sodium, magnesium, calcium, iron, zinc, copper and manganese) in regions of the rat brain.

The effect of severe zinc deficiency on the distribution of nine elements (potassium, phosphorus, sodium, magnesium, calcium, iron, zinc, copper and manganese) in brain regions (olfactory lobes, right and left hippocampi, cerebellum and the rest of the brain) has been studied. After male rats (30 days old) were fed a zinc-deficient diet for 28 days, the zinc concentration of most brain parts was similar to zinc-adequate control values. Olfactory lobe zinc, on the other hand, was slightly depressed. However, the levels of other metals were dependent on zinc nutriture. Zinc deficiency caused an elevation in copper concentrations in most brain parts. Restriction of food intake caused a similar increase in brain copper but generally the effect was less than with zinc deficiency. Levels of calcium, manganese, sodium and potassium, in certain brain regions, also appeared to be altered by the zinc status of an animal. Of the minerals examined, only zinc and copper displayed asymmetrical distribution between the right and left hippocampus, and severe zinc deficiency did not affect lateral distribution of these trace metals in the hippocampus. The data suggest the hypothesis that changes in brain metal content, associated with zinc deficiency, contribute to the behavioral abnormalities that occur.

Animals↗
PubMed1983

Studies on the bioavailability of zinc in humans: mechanism of the intestinal interaction of nonheme iron and zinc.

The mechanisms of the previously described competitive zinc:iron interaction were explored in healthy human volunteers, using the increment in plasma zinc concentration after an oral dose of 25 mg of zinc as zinc sulfate as the index of zinc absorption. Ferric iron in a 2:1 Fe/Zn ratio reduced the plasma uptake of zinc, but to a significantly lesser degree than ferrous iron; addition of 1 g of ascorbic acid increased the magnitude of the inhibitory effect of ferric iron to that seen with ferrous iron. An inverse relationship between some indices of iron status in adult women, or of parenteral iron administration in a child, and the magnitude of zinc:iron interaction was observed. Saturation of the intestinal mucosa with consecutive-day doses of therapeutic iron did not influence the uptake of zinc administered alone or in the context of a 2:1 ferrous iron:zinc ratio in solution. The results are most consistent with a combination of an intraluminal competition of the two minerals and an intracellular competition at a site "distal" to the regulatory step by which iron nutriture modulates the entry of iron into the body, but "proximal" to the site at which the daily administration of therapeutic doses of iron blocked the passage of dietary iron.

Adult↗
PubMed1983

The effect of interactions between dietary egg white protein and zinc on body weight, bone growth and tissue trace metals in the 30-day-old rat.

Nine groups of 30-day-old rats were fed different diets, which contained 8, 15 or 20% egg white (equivalent to 6.0, 11.3 and 15.0% protein, respectively) each at 3 levels of zinc (6, 12 and 18 ppm zinc) for 30 days. The rats consuming the 6.0% protein, regardless of zinc intake, gained less weight than the groups fed 11.3 or 15.0% protein. Plasma zinc was not influenced by dietary egg white protein content, whereas, plasma zinc levels were lower in the rats fed 6 ppm dietary zinc compared to those fed 12 or 18 ppm zinc. Of the liver trace metals measured, only iron appeared to be influenced by an egg white protein-zinc interaction. Increasing dietary egg white protein led to increased concentrations of liver zinc and magnesium. Dietary zinc levels had no effect on the concentration of these metals in the liver. Liver calcium and copper concentrations were not significantly influenced by either dietary zinc or egg white protein. Femur weights and lengths were lower in the rats fed 6.0% than in those fed 11.3 or 15.0% protein diet but were unaffected by dietary zinc. Femur width was related to dietary protein and zinc. Dietary protein and zinc were interrelated in their affect on femur zinc levels. Femur zinc concentrations increased with increasing dietary zinc levels. Also femur zinc levels decreased with increasing dietary protein content. Other femur metal (copper, iron and calcium) concentrations were higher in rats fed the low level versus the higher levels of protein, but were not influenced by dietary zinc. These results show that dietary zinc and egg white protein are interrelated with regard to their effect on body and femur growth and tissue trace metal content.

Animals↗
PubMed1983

Oxidation of alanine and beta-hydroxybutyrate in late gestation by zinc-restricted rats.

The day 21 response of the Long-Evans pregnant rat to marginal dietary zinc intake was investigated in this experiment. Day 20 and 21 food intakes of zinc-restricted dams were below the control group amounts and indicated that dietary nitrogen and energy did not meet gestation requirements. Intravenous injections of tracer doses of [14C]alanine provided evidence for decreased oxidation of the carbon chain of alanine when zinc-restricted were compared to control dams. The plasma pool size of beta-hydroxybutyrate and the rate of 14CO2 production following injection of the radioactively labeled ketone body indicated that substantial increases in the oxidation of beta-hydroxybutyrate were induced by restricted zinc feeding. Maternal plasma concentrations of alanine were marginally reduced, beta-hydroxybutyrate increased, and glucose unchanged by the suboptimal zinc diet. Litter weights at day 21 were moderately depressed (-11%) by maternal zinc-restriction, suggesting that the chronic effects of mild dietary zinc deficiency are most apparent near term in this animal model.

3-Hydroxybutyric Acid↗
PubMed1983

Potential errors in body composition as estimated by whole body scintillation counting.

Vigorous exercise has been reported to increase the apparent potassium content of athletes measured by whole body gamma ray scintillation counting of 40K. The possibility that this phenomenon is an artifact was evaluated in three cyclists and one nonathlete after exercise on the road (cyclists) or in a room with a source of radon and radon progeny (nonathlete). The apparent 40K content of the thighs of the athletes and whole body of the nonathlete increased after exercise. Counts were also increased in both windows detecting 214Bi, a progeny of radon. 40K and 214Bi counts were highly correlated (r = 0.87, p less than 0.001). The apparent increase in 40K was accounted for by an increase in counts associated with the 1.764 MeV gamma ray emissions from 214Bi. Thus a failure to correct for radon progeny would cause a significant error in the estimate of lean body mass by 40K counting.

Adolescent↗
PubMed1982

Longitudinal study of brain function and depletion of iron stores in individual subjects.

Seven men living in a controlled research unit showed decrements in iron stores due to repeated phlebotomy. For each subject, weekly measures of cognitive task performance, electroencephalographic (EEG) power and Event-Related Potentials (ERPs) were examined in relation to serum ferritin level. No reliable relationships of ferritin level to cognitive performance ability were observed. Some EEG findings appeared similar to previous observations on EEG data and iron status in cross-sectional research. For four of the seven subjects, asymmetries of EEG power in the occipital electrodes appeared related to the decline in iron status over time.

Adult↗