Search PubMed⌕ Search

Biomedical subjects

M R Fox

Publications and source records attributed to M R Fox.

At least 37 records · Page 2Linked to original sources
PubMed1979

Effects of nutritional factors on metabolism of dietary cadmium at levels similar to those of man.

Several nutrients are known to affect cadmium toxicity, but little is known about the effect of dietary nutrient levels on absorption and tissue retention of cadmium at low dietary levels, similar to those of man. Feeding gradedlevels of zinc in a casein-gelatin diet to young Japanese quail with 109Cd (as the chloride) and 0.062 ppm added cadmium decreased the cadmium concentrations in the proventriculus-ventriculus, duodenum, jejunum-ileum, and the liver, but not in the kidney. Zinc also affected some zinc, iron, manganese, and copper tissue levels. Different tissue concentration patterns of cadmium and essential minerals were obtained with two purified control diets, one based on casein-gelatin and the other on soy isolate as the principal protein sources. The data show that relatively small dietary changes can markedly affect tissue levels of cadmium and that a low intake of zinc may increase the risk to dietary cadmium exposure. The complexity of the nutrient interrelationships and their effects on cadmium require further study to define mechanisms, which may be similar to those produced by low cadmium intakes in man.

Animal Nutritional Physiological Phenomena↗
PubMed1979

Nutritional influences on metal toxicity: cadmium as a model toxic element.

The nutrient quality of the diet has been shown repeatedly to be a significant factor in modifying the response of man and animals to toxic element exposure. Deficiencies of several essential nutrients have been shown to exacerbate the effects of cadmium and supplements of such nutrients have been shown to ameliorate the toxicity. Thus the effects of exposure to a toxic element, such as cadmium, may vary, depending on interactions with other elements which are present in the diet in different concentrations.

Adolescent↗
PubMed1978

Nutritional considerations in designing animal models of metal toxicity in man.

In recent years, exposure of man to increasing amounts of metals has occurred rather generally from industrial contamination and variably from intake of dietary mineral supplements. Adverse effects of individual metals can be markedly altered by dietary levels of other essential and nonessential inorganic elements, essential organic nutrients and other nonessential dietary components. Experimental diets for establishing baseline responses to excess elements should be formulated to meet the animal's requirements only. These reference diets can then be modified to mimic man's average dietary intake as well as meal patterns. Improved animal models should provide better data for assessing hazards of excess metal intake by man.

Aging↗
PubMed1978

Experimental zinc deficiency in humans.

The effects of a mild zinc-deficient state in humans were studied. Four male volunteers received restricted zinc intake for several weeks under strict metabolic conditions. As a result of dietary zinc restriction, a decrease in zinc concentration of plasma, erythrocytes, leukocytes, and urine was observed. Changes in the activities of zinc-dependent enzymes in the plasma such as alkaline phosphatase and ribonuclease were also related to the dietary zinc status. An adverse effect of zinc restriction on total protein, total collagen, ribonucleic acid, and the activity of deoxythymidine kinase (a zinc-dependent enzyme) in the sponge connective tissue of the two volunteers in whom this test was done was noted. During the zinc restriction period, the ammonia level in the plasma was elevated. Weight loss occurred in all subjects as a result of dietary zinc restriction. Inasmuch as the zinc-deficient state was mild, this study provides a basis for developing diagnostic criteria for zinc deficiency in humans.

Aged↗
PubMed1977

Delta-aminolevulinic acid dehydratase--a sensitive indicator of lead exposure in Japanese quail.

Red blood cell delta-aminolevulinic acid dehydratase (RBC-ALAD) activity has proven to be a sensitive indicator of lead exposure in humans. The depressed enzyme activity and its negative correlation to blood lead concentrations are well-known effects of lead exposure in man. The sensitivity of RBC-ALAD activity in young Japanese quail exposed to low levels of lead as lead acetate was investigated. Two groups of nine birds each were fed purified diets containing either no added lead or 25 micrograms of lead per g. of diet. After 2 weeks, blood samples for hematocrit, hemoglobin, and enzyme determinations and renal, hepatic, duodenal, and tibial tissues were collected. There were no significant differences between controls and lead-fed birds in body, kidney, duodenal, and tibial weights, or in hematocrit and hemoglobin concentrations. However, the renal, hepatic, duodenal, and tibial lead concentrations were significantly (P less than 0.001) greater in the lead-treated birds. The activity of RBC-ALAD in the group fed lead was 45% of that in the control group; these values were significantly different (P less than 0.001). RBC-ALAD activity expressed as the log. base 10 showed significant (P less than 0.02) negative correlation with both hepatic and tibial lead. The study demonstrates that the activity of RBC-ALAD in the Japanese quail is a very sensitive indicator of lead exposure.

Animals↗
PubMed1976

Magnesium deficiency, requirement and toxicity in the young Japanese quail.

Studies of magnesium deficiency, requirement and toxicity in the young Japanese quail (Coturnix coturnix japonica) were conducted. Day-old birds were fed an adequate purified diet containing 35% soy protein to 2 weeks of age. Residual magnesium in the diet without any added magnesium salts was 21 p.p.m. magnesium was supplied by graded amounts of MgSO4 to a total of 11 levels ranging from 125 to 2,000 p.p.m. Deficiency signs included poor growth, and occasionally excitability, gasping and convulsions. Most mortality occurred during the first 7 days. The maximum dietary magnesium concentrations that produced the minimal significant deviation from normal values for mortality, body weight, hemoglobin and tibia ash was 225, 200, 250 and 250 p.p.m., respectively. Based on these measurements, 300 p.p.m. magnesium is considered adequate to meet the young quail's requirement under the conditions of these experiments. With 2,000 p.p.m. magnesium, the only adverse effect was an increase in mortality. Between 200 and 1,000 p.p.m. magnesium there was a linear relationship between concentration of magnesium in the tibia and the log of the concentration of dietary magnesium. This suggests that tibia magnesium concentration might be useful for bioassay of magnesium in foodstuffs.

Animals↗
PubMed1975

Protective effects of ascorbic acid against toxicity of heavy metals.

Toxicity of cadmium in the young Japanese quail rapidly produced moderate growth depression, hypogonadism in the male, decreased bone ash, severe anemia, alterations of "indicator" tissue levels of several essential inorganic elements, and marked histological abnormalities of the duodenum, bone marrow, adrenal medulla, and esophageal mucus glands. Cadmium appeared to have direct effects on zinc and iron, particularly iron (III), by decreasing intestinal absorption of these elements. Small amounts of dietary ascorbic acid were protective against many of the adverse effects of cadmium. The young quail proved to be a useful species for these studies. The experience with cadmium may have some facets that would prove useful in further studies of the effects of ascorbic acid on the toxicity of other metals.

Anemia, Hypochromic↗
PubMed1975

Combined zinc and iron compared with iron supplementation of diets of 6- to 12-year old village schoolchildren in southern Iran.

The effects of supplementation of the diets of 6- to 12-year-old children in a village near Shiraz in Iran with zinc plus iron or iron alone, together with the indispensable amino acids in the form of egg white protein, vitamins, minerals, and corn oil have been evaluated. Initially 48 of 59 children had zinc concentrations below the minimum found in well-nourished persons. Eight months of supplementation with zinc plus iron (20 mg daily of elemental zinc as carbonate and 20 mg ferrous iron as fumarate) failed to stimulate growth or bone development or to bring about an increase in plasma zinc concentrations. However, supplementation with iron in the above amount was associated with an acceleration of growth in height and weight. The persistence of low concentrations of zinc in plasma and the failure of supplemental zinc to stimulate growth are attributed to the poor availability of both dietary and supplemental zinc resulting from sequestering action of fiber and phytate present in large amounts in the unleavened whole meal bread consumed by villagers. In addition, the results suggest that simultaneous administration of iron and zinc supplements may impair utilization of the metals.

Alkaline Phosphatase↗