Normal human skin fibroblast cells were used to study the effect of zinc supplementation of the media on cell growth and the competitive binding activity of low density lipoprotein (LDL). Cells were grown in the media containing Dulbecco's Modified-Eagle Medium (DMEM), 5% (v/v) fetal calf serum (FCS), and various levels of zinc. Cell counts and protein determination revealed that there was no stimulatory effect of zinc on the growth of cells, showing a flat growth curve with up to 6 μg/ml zinc supplementation. However, zinc supplementation of greater than 6 μg/ml to the medium appeared to be toxic to the cell and thereby prevented growth. When zinc was removed from the medium using Epoxy-activated Sepharose 6B coupled with iminodiacetate, zinc concentration in the medium was markedly reduced to 0.045 μg/ml from 0.210 μg/ml. The cell growth study using this zinc depleted medium exhibited a growth curve similar to that obtained from the earlier study, suggesting that 0.045 μg/ml of zinc in the control medium was still sufficient to support normal cell growth. For the LDL binding study, cells were grown in the media with various levels of zinc supplementation for 7 days and the competitive binding activity of LDL was determined. When cells were grown in the zinc removed medium with 1.5 μg/ml zinc supplementation, the maximum amounts of ¹²⁵I-LDL bound and internalized in the cells were observed; however, higher levels of zinc supplementation to the growth medium caused decreased ¹²⁵I-LDL binding to the cell receptors. These results suggest that zinc may be involved in the binding of LDL to the receptors. / Graduation date: 1983

Graduation date: 1969

published_or_final_version / Pharmacology / Doctoral / Doctor of Philosophy

The present study was carried out to determine the effects and possible mechanism of action of zinc supplementation on the in vitro growth of malignant murine melanoma (B16) and non-malignant monkey kidney (LLCMK) cells. Cell culture studies showed that zinc supplementation significantly inhibited B16 growth at all the concentrations studied (1, 3, 5 and lOμg/ml). Zinc was also found to inhibit the growth of the LLCMK cells, although to a lesser extent than the B16 cells. Possible evidence of mobilisation of the essential fatty acids from the membrane phospholipid stores was noted in both cell types. This effect was, however, greater in the B16 cells. Δ⁶-desaturase activity was found to be significantly lower in the B16 cells than in the LLCMK cells (p ≥ 0.05). Zinc supplementation resulted in an increase in the enzymes activity in the LLCMK cells and, at high concentrations, in the B16 cells. An estimation of elongase and Δ⁶-desaturase activity with zinc supplementation indicated that zinc had little or no effect on the activity of these enzymes. B16 cells were found to have higher levels of free radicals than the LLCMK cells. Zinc supplementation resulted in increased free radical formation in the B16 cells, while no effect was observed in the LLCMK cells. Lipid peroxidation increased in both cell types with increased zinc concentrations. The observed effect of zinc supplementation on cell growth may involve these elevated levels of lipid peroxides. CycIo-oxygenase activity was found to be greater in the B16 cells than the LLCMK cells. The activity of the enzyme increased with higher concentrations of zinc (lOμg/ml) in both cell types. Prostaglandin E, levels were found to be lower in the B16 cells compared to the LLCMK cells. The levels of prostaglandin E, in both cell types appeared to be dependent on the levels of the polyunsaturated fatty acid precursors to the prostaglandins. Zinc was found to inhibit the activity of the enzyme adenylate cyclase in both cell types. The cAMP levels in the LLCMK cells were also found to decrease with zinc supplementation. In the case of the B16 cells, cAMP levels increased at low concentrations of zinc despite a decrease in adenyl ate cyclase activity, suggesting a possible inhibition of cAMP phosphodiesterase activity at these concentrations of zinc. It is concluded that although zinc supplementation does have an effect on cell growth, this effect is not mediated through the activation of adenylate cyclase by the prostaglandins resulting in elevated levels of cAMP. A possible mechanism involving lipid peroxidation is proposed.

The effects of 18 milligrams elemental zinc as zinc sulfate were investigated in 24 hemodialysis patients during a double blind study. The study was conducted at two different dialysis centers in Utah. Each patient was evaluated for a 12 week period. The effects of zinc supplementation were evaluated using the parameters of serum zinc, hair zinc, dialysate zinc, and objective and subjective taste evaluation procedures. To possibly clearify the above determination in zinc status, copper determination were made of the same parameters. In addition, determinations of serum ferritin, transferrin and iron levels were made. A three day diet record was used to document the dietary intakes of calories, protein, and zinc as well as indicate the balance of food groups in the diets. Patients were evaluated biweekly throughout the study period. There were a total of six evaluations made on each participant during the investigation. Complete data were collected on six patients in the treatment group, and on ten patients in the control group. Even though the sample size was small, results were very steady and values fell within narrow ranges for most parameters examined. The mean baseline serum zinc value (n = 24) was 56 micrograms per deciliter. Patients, by this value would be classified as zinc deficient. However, the hair zinc levels were within the normal range, and no other signs or symptoms of zinc deficiency were evident in any patient, other than altered taste. There were no differences between pre and post dialysis serum zinc levels, nor were there any consistent increases in zinc levels cleared from the plasma during dialysis. There were no increases seen in the serum zinc or hair levels in response to zinc supplementation. Furthermore, there was no significant improvement in the taste acuities of the treatment group patients compared to the controls. The low serum levels maintained were probably due to the redistribution of body zinc known to occur in uremia. Most patients improved their taste test scores. This displayed the learning phenomena that was inherent in the taste testing technique. Furthermore, hemodialysis patients and the failure of many subjects to identify all four tastants (sweet, sour, bitter, and salt) correctly. Daily dietary intakes of high bioglogical value protein and zinc by the patients were less than the amounts recommended by the National Dietary Counsil and the physicians. However, the daily intakes of protein (55 grams) and zinc (7.9 milligrams) were not limited to the level where deficiency signs or symptoms of either nutrient were seen. Copper serum levels were all within the normal range. The mean baseline level for all patients was 113 micrograms per deciliter. Copper status appeared unaffected by uremia or hemodialysis. Body stores of iron, determined by serum ferritin levels, ranged from possibly indicating iron deficiency to iron overload. The body iron stores did not correlate with patients’ responses to the oral zinc supplementation.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

No description available.

No description available.

Sandra J. Chapman. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 95-103). / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- History of zinc --- p.1 / Chapter 1.2 --- The biological role of zinc --- p.2 / Chapter 1.3 --- Zinc toxicosis --- p.6 / Chapter 1.4 --- Mechanisms of zinc uptake and transport in fungi --- p.7 / Chapter 1.5 --- Bioremediation --- p.11 / Chapter 1.6 --- Uptake of heavy metals by fruit bodies of edible mushrooms --- p.13 / Chapter 1.7 --- Mushroom fungi selected for study --- p.15 / Chapter 1.8 --- Purpose of study --- p.17 / Chapter 2. --- Materials and Methods --- p.18 / Chapter 2.1 --- Organisms --- p.18 / Chapter 2.2 --- Media --- p.18 / Chapter 2.3 --- Media chelation --- p.20 / Chapter 2.4 --- Chemicals --- p.20 / Chapter 2.5 --- Zinc content of fruit bodies grown on substrates containing different concentrations of zinc --- p.21 / Chapter 2.5.1 --- Substrate preparation for V. volvacea inoculum --- p.21 / Chapter 2.5.2 --- Cultivation of V. volvacea fruit bodies --- p.21 / Chapter 2.5.3 --- Cultivation of P.sajor-caju fruit bodies --- p.22 / Chapter 2.5.4 --- Cultivation of L. edodes fruit bodies --- p.23 / Chapter 2.5.5 --- Preparation of biological material for atomic absorption spectrophotometry --- p.24 / Chapter 2.6 --- Effect of different concentrations of zinc on the growth of six mushroom fungi --- p.25 / Chapter 2.6.1 --- Radial growth study --- p.25 / Chapter 2.6.2 --- Biomass study --- p.26 / Chapter 2.7 --- Microscopic studies of V. volvacea --- p.27 / Chapter 2.7.1 --- "Coomassie Blue preparation, staining of V.volvacea hyphae" --- p.27 / Chapter 2.7.2 --- Dithizone staining of V. volvacea hyphae --- p.27 / Chapter 2.7.3 --- Fluorescence microscopy --- p.28 / Chapter 2.7.4 --- Scanning electron microscopy --- p.28 / Chapter 2.8 --- Preparation and analysis of V. volvacea proteins using gel electrophoresis --- p.29 / Chapter 3. --- Results --- p.33 / Chapter 3.1 --- Zinc Uptake by Fruit Bodies --- p.33 / Chapter 3.1.1 --- Uptake of zinc by V. volvacea --- p.33 / Chapter 3.1.2 --- Uptake of zinc by P. sajor-caju --- p.33 / Chapter 3.1.3 --- Uptake of zinc by L. edodes --- p.34 / Chapter 3.1.4 --- Symptoms of zinc toxicity in L. edodes --- p.44 / Chapter 3.2 --- Growth studies --- p.49 / Chapter 3.2.1 --- Radial growth measurements --- p.49 / Chapter 3.2.2 --- Biomass measurements --- p.56 / Chapter 3.2.3 --- Morphological alterations due to zinc observed with light and electron microscopy --- p.63 / Chapter 3.3 --- V. volvacea staining studies --- p.73 / Chapter 3.3.1 --- Protein staining using Coomassie Blue --- p.73 / Chapter 3.3.2 --- Zinc staining by dithizone and fluorescence staining by DAPI --- p.75 / Chapter 3.4 --- V. volvacea protein profile comparisons after gel electrophoresis --- p.81 / Chapter 4. --- Discussion --- p.83 / Chapter 4.1 --- Zinc uptake by fruit bodies / Chapter 4.1.1 --- Uptake of zinc by V. volvacea and P. sajor-caju fruit bodies --- p.83 / Chapter 4.1.2 --- Accumulation of zinc by L. edodes fruit bodies and mechanism of toxicity --- p.84 / Chapter 4.2 --- Effects of zinc on growth --- p.88 / Chapter 4.3 --- V. volvacea mechanisms of tolerance --- p.89 / Chapter 4.4 --- Differences in protein profiles of V. volvacea grown on different concentrations of zinc --- p.93 / Chapter 5. --- References

The effects of single and combined dietary protein and zinc restrictions on the outcome of primary and challenge infections with the intestinal nematode Heligmosomoides polygyrus in mice were examined using a 3 x 2 factorial design that combined three levels of dietary protein (24% - control; 7% - marginal; 3% - low) with 2 levels of dietary zinc (60 mg/kg - control; 3 mg/kg - marginal). Protein and zinc restrictions, at these levels, produced independent effects on final worm burdens. While mice fed both marginal and low protein diets, and marginal zinc diets had significantly higher worm burdens in a primary infection, the response to a challenge infection was only impaired in animals fed the low protein diet. Eosinophilia was significantly reduced by zinc restriction in the primary infection and by the lowest level of protein restriction in the challenge infection. The magnitude of the serum IgG1 concentration was significantly lowered by protein restriction in both the primary and challenge infections. The impaired response to a challenge immunizing protocol in the animals fed the 3% protein diet, along with the reduced eosinophilia and IgG1 response, indicates a negative effect of protein deficiency on the host immune response to an intestinal nematode infection.