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Biomedical subjects

D B Cheek

Publications and source records attributed to D B Cheek.

At least 37 records · Page 2Linked to original sources
PubMed1981

Evidence for zinc deficiency in aboriginal settlements in Northwestern Australia.

Four coastal Aboriginal settlements in the northwest area of Australia have been investigated for plasma trace metal status--Zinc (Zn), Copper (Cu), and Iron (Fe). The 350 Aboriginals were considered in two groups; five to 20 years of age and 20 to 70 years of age. Forty per cent to 50% had plasma Zn levels below two standard deviations from the normal and 60% to 70% had plasma Cu levels greater than two standard deviations above the normal (almost 100% at Kalumburu). Hypoferraemia was common. These results are more significant than those of a previous study of 350 individuals living at two inland settlements. The coastal missions have access to fresh meat and fish, and at Kalumburu food is prepared for the people. While the climate, soil, and the Aboriginal predilection for white flour may play a role, it is speculated that the Zn deficiency is related to parasitic infestation in the intestine, loss of blood, and failure of zinc absorption.

Adolescent↗
PubMed1981

Sulfate uptake and somatomedin levels in the "little' (lit/lit) mouse.

The mutant "little' (lit/lit) mouse is deficient in growth hormone and has correspondingly low levels of serum somatomedin. Injection of these mice with human or bovine growth hormone significantly raises serum somatomedin levels within 6 h. In vivo uptake of radioactive sulfate by costal cartilage in lit/lit mice is similar to that of normal mice, which is unexpected in view of the low levels of circulating somatomedin. If costal cartilage from normal and lit/lit mice are preincubated in medium 199 in vitro before transfer to fresh medium containing radioactive sulfate and serum, there is not consistent difference in uptake of sulfate, demonstrating similar endogenous cartilage activity. In contrast, omission of the preincubation step reveals a lower uptake of sulfate in vitro by cartilage from lit/lit mice as compared with normal mice. Cartilage removed from lit/lit mice 24 h after injection with growth hormone, however, takes up greater amounts of sulfate than cartilage from untreated normal mice. Taken together, these data suggest that the level of circulating somatomedin is not a dominant factor in controlling the uptake of radioactive sulfate into costal cartilage of mice in vivo. This cells into question the relationship between somatomedin levels, in vivo rates of sulfate incorporation and rates of growth.

Animals↗
PubMed1981

Urinary steroid metabolites and the overgrowth of lean and fat tissues in obese girls.

Studies were made of steroid metabolites excreted in the urine of 17 obese girls 11.4 to 16.8 yr and 17 normal girls 11 to 17 yr. Creatinine excretion (muscle mass), total body water (or deuterium space), lean body mass and body fat were determined in the obese girls. Extracellular volume (corrected bromide space) was also measured and by difference with body water, intracellular water or soft tissue cell mass was calculated. In normal girls 24-h creatinine excretion was determined, but body water was predicted from height and weight. It was found, as in previous studies, that the obese girls had excess muscle mass and soft tissue cell mass for height. The excess growth of muscle, lean tissue, and body length in obese girls correlated with increments in oxosteroid (17 ketosteroid) excretion. The overall weight increase correlated with increased excretion of corticosteroid metabolites--a finding of interest since a physiological Cushing's syndrome was postulated for fat girls many years ago. When the normal and obese girls were divided by age at 14 yr and the subgroups compared (normal obese) the younger girls showed differences with respect to height, weight, total body water, fat and percentage fat. Differences in steroid metabolites were not found. In older girls the same findings were made again, but here it was clear that the increments in body size, particularly muscle mass, correlated with augmented oxosteroid excretion. Evidence is cited that these findings are not just related to a larger steroid pool in obese girls.

17-Ketosteroids↗
PubMed1981

Zinc, copper and environmental factors in the aboriginal peoples of the North West.

Three-hundred Aboriginal people five to 70 yr have been studied at three missions in the north west of Australia-Beagle Bay, Lombadina and One Arm Point. The prevalence of hypozincaemia and hypercupraemia (a departure of more than 2 S.D. from the expected normal) has been assessed. Plasma iron concentration was determined. Half of the individuals had hypozincaemia and for some age groups the prevalence was greater (almost 100% for 15 to 20-year-old females at Lombadina). Hypercupraemia was prevalent and ranged from 70 to 100% for most age groups. Hypoferraemia was detected frequently. By the use of anthropometric methods the children were found to be growth retarded and to have reduced weight for height. These people are known to be infected with intestinal parasites which cause bleeding into the bowel or malabsorption which can cause losses of zinc or failure of adsorption. They prefer unleavened bread which contains phytic acid which inhibits zinc absorption. The soil is zinc deficient and the climate conducive to large losses of zinc in sweat. Geophagia is practiced and pica is found to occur in children. Preliminary evidence of elevated copper status is available. We speculate that growth failure may be related to zinc deficiency or copper toxicity.

Adolescent↗
PubMed1981

Compensatory renal growth in the mouse. I. Allometric approach to the effect of age.

Allometry, defined as the relationship between the growth rates of organs to the weight of the whole body (38), was used to study the effect of age on the degree of compensatory renal growth (CRG) in the mouse. The normal growth of the kidneys relative to body weight (BW) was determined in animals between 5 to 50 days of age. In one group, nephrectomy and sham operations were performed at 5, 15, and 35 days of age. The remaining ("renoprival") kidney was removed 15 days postnephrectomy. In a second group, nephrectomy was performed on 5-day-old animals, the renoprival kidney being removed after 30 or 45 days. Regression equations were calculated by least-squares after logarithmic transformation and different groups were compared by analysis of covariance. The regression equation for the control kidney was kidney weight (KW) = 0.0093 BW0.86 (r = 0.96). The regression for renoprival kidneys in females was KW = 0.0142 BW0.83 (R = 0.96) after 15 days and, in comparison, was not significantly different from 30 to 45 days. The interval between control and renoprival regressions was equivalent to a difference of congruent to 43% KW. In male mice, the regression for renoprival kidneys after 15 days was KW = 0.0103 BM0.96 (r = 0.98) and was not significantly different from 30 to 45 days. This study suggests that in young mice the time required for complete CRG may be a maximum of 15 days and that the amount of CRG does not depend on the age at operation. After CRG, a new equilibrium is reached which is thereafter maintained up to a minimum of 50 days of age.

Adaptation, Physiological↗
PubMed1981

Compensatory renal growth in the mouse. II. The effect of growth hormone deficiency.

Allometry was used to study the effect of growth hormones (GH) deficiency on compensatory renal growth (CRG) in a dwarf mouse strain (Little). Nucleic acid and protein estimations were used to assess changes in cellular hyperplasia and hypertrophy. Nephrectomy was performed at 5, 15, or 35 days of age with removal of the renoprival kidney 15 days later. Controls underwent sham nephrectomies at 35 days of age. The allometric growth of the normal kidney in the homozygote dwarf (lit/lit) between 8 and 50 days of age was closely related to that of the normal heterozygote (lit/+). A regression line for the renoprival kidneys in lit/lit animals was parallel to that of the control right kidney (P less than 0.001). The interval between the regression lines was equivalent to a constant difference of approximately 40% between renoprival and control right kidneys and was similar to that found in the normal heterozygote (43%). Increases in DNA, RNA, and protein in control animals during CRG indicate that cell division and hypertrophy were occurring in similar proportions. In the GH-deficient mouse, the total amount of DNA in renoprival kidneys was 0.451 mg compared with 0.439 mg in controls (NS). This suggests that cell replication was suppressed. The protein:DNA ratio increased from 20.91 to 24.27 (P less than 0.001) and the RNA:DNA ratio increased from 0.732 to 0.912 (P less than 0.001), suggesting that cell size was markedly increased. These findings suggest that reduced amounts of GH may produce a dissociation between hyperplasia an hypertrophy, with CRG occurring predominantly by cellular hypertrophy.

Adaptation, Physiological↗
PubMed1980

Serum and plasma zinc, copper and iron concentrations in Aboriginal communities of North Western Australia.

Two aboriginal communities situated in the tropical north-west of the Australian continent have been investigated in regard to trace metal status (zinc, copper, and iron) and other laboratory and epidemiological information. A total of 364 persons, ranging in age from 5 to 77 years were studied. The incidence of hypozincemia (serum or plasma zinc concentration less than 0.71 micrograms/ml) of the two communities when combined was 24.4%, while hypercupremia (defined as serum or plasma copper levels greater than 1.38 micrograms/ml) was 47.9%. Depressed serum iron levels were demonstrated in more than 50% of the Aborigines studied. Hypozincemia was most prevalent (incidence 31 to 67%) in children at the time of the important pre- and postadolescent growth period (10 to 15 years) and in women beyond 60 years of age (incidence 33 to 64%). Serum total protein and vitamin B12 levels tended to be increased. Mild anemia was seen in approximately one in five persons aged less than 20 years. Intestinal parasites and pathogenic enterobacteria were frequently isolated in fecal specimens. In one community, half of the persons examined had positive isolates of enteric pathogens. Intestinal parasites predominated and were more frequently isolated from persons aged less than 20 years. Ancylostoma duodenale accounted for 32% of the pathogens isolated. Evidence is presented that suggests that both communities are exposed to numerous bacterial, viral, and parasitic infections. The diet consumed in these communities is predominately white flour and refined sugar. Geophagia is practiced in this area of Australia. It is emphasied that all the etiological prerequisites and many of the laboratory findings ascribed to the zinc deficiency syndrome appear to be operating in the two Aboriginal communities studied.

Adolescent↗
PubMed1978

Assessment of protein reserves (cellular mass) in Aboriginal children.

The body protein reserves, assessed indirectly by the measurement of intracellular water, was determined in free-living Aboriginal children and adolescents located in Central and Northwestern Australia. Fifty one individuals were studied--31 males and 20 females. Significant reductions were observed in intracellular water or cell mass relative to the cube of body length for Aboriginal females when compared to a control female group. Only marginal or borderline differences for the same parameters were observed when Aboriginal males were compared with controls. Comparison of Aboriginal females with Aboriginal males demonstrated significant reductions in cell mass (intracellular water) relative to body length cubed in the female. This finding in the Aboriginal female is of concern because many become pregnant in the early teenage years. Evidence was found during the course of this study that plasma zinc concentrations were frequently low. This led to a concomitant study on serum and plasma trace metals in two Aboriginal settlements (364 individuals) to be published in a subsequent paper.

Adolescent↗
PubMed1976

Nutritional studies in the pregnant rhesus monkey--the effect of protein-calorie or protein deprivation on growth of the fetal brain.

Twenty four pregnant nulliparous rhesus monkeys were distributed in three groups. While pregnant, the mothers were fed a diet, adequate in mineral and vitamins, that afforded 4.2 g protein and 100 cal; 1.2 g protein and 100 cal; or 1.2 g protein and 50 cal per kg per day. The fetuses were taken by cesarian section at 156 days gestation (term = 165 days) and the cerebrum and cerebellum were subsequently analysed chemically to assess composition and growth. Analyses revealed no statistically significant changes in protein, DNA, RNA, cholesterol, phospholipid, water, or chloride space of either tissue. The zinc concentration per gram of cerebral tissue or protein was significantly elevated in the low protein low calorie group. These results indicate that the brain of the fetus of this primate is protected during frank protein-calorie restriction of the mother. Moreover it is during this time that the major part of brain development takes place. It is argued that the differences observed after maternal restriction of protein and/or calories in subprimate mammals are not necessarily applicable to the human situation.

Animals↗