Anergy, zinc deficiency, and decreased nucleoside phosphorylase activity in patients with sickle cell anemia

Cell-mediated immunity was evaluated in 26 patients with sickle cell anemia using skin tests for delayed hypersensitivity reactions. Patients with impaired delayed hypersensitivity reactions had lower zinc levels in plasma, erythrocytes, and neutrophils than patients with normal delayed hypersensitivity reactions or controls. The activity of nucleoside phosphorylase, an enzyme essential for T-lymphocyte function, was significantly lower in zinc-deficient patients with anergic sickle cell anemia. We conclude that zinc deficiency in patients with sickle cell anemia is associated with impaired delayed hypersensitivity. Decreased activity of nucleoside phosphorylase may be partially responsible for lymphocyte dysfunction in these patients.

Zinc deficiency: a reversible complication of uremia

Subnormal plasma zinc levels and decreased zinc concentration in hair and leucocytes as well as increased plasma ammonia and ribonuclease activity in dialyzed and nondialyzed uremic patients indicate that zinc metabolism is abnormal in uremia and is not corrected by dialysis. The effect of oral supplementation with zinc acetate (12 patients) or placebo (12 patients) on the above biochemical parameters in hemodialysis patients was determined as a part of a double-blind study. The zinc-supplemented, but not the placebo, group demonstrated significant increases in mean (+/- SD), plasma zinc (80 +/- 9 to 110 +/- 14, micrograms/dl), leucocyte zinc (56 +/- 13 to 1098 +/- 18, micrograms/10(10) cells), hair zinc (140 +/- 12 to 190 +/- 16 micrograms/g), and decreases in plasma ammonia (76 +/- 10 to 40 +/- 6 micrograms/dl) and plasma ribonuclease activity (1.49 +/- 0.08 to 0.78 +/- 0.10, OD/min/ml). Abnormalities of taste and sexual function improved significantly in patients receiving zinc but not in those on placebo therapy. These improvements in biochemical as well as clinical parameters confirm and extend our earlier observations of improvement in taste and sexual function after zinc supplementation. Together, they suggest that zinc deficiency is a complicating feature of uremia and can be corrected by oral zinc supplementation.

Effect of oral zinc therapy on gonadal function in hemodialysis patients. A double-blind study

Zinc deficiency may account for the persistence of gonadal dysfunction in a majority of uremic men despite adequate dialysis. Twenty stable patients having hemodialysis three times a week completed a double-blind trial using either 50 mg of elemental zinc as zinc acetate (10 patients) or placebo (10 patients), orally. At the end of the 6-month study period, a significant increase in the mean (+/- SE) plasma zinc (75 +/- 2 micrograms/dL to 100 +/- 2 micrograms/dL, p less than 0.001), serum testosterone (2.8 +/- 0.3 ng/dL to 5.2 +/- 0.5 ng/mL, p less than 0.001), and sperm count (30 +/- 3 million/mL to 63 +/- 5 million/mL, p less than 0.001) occurred in the zinc-treated group, but not in those receiving the placebo. The zinc-treated group also had a significant fall in serum luteinizing hormone (92 +2- 10 mIU/mL to 49 +/- 26 mIU/mL, p less than 0.005) and follicle stimulating hormone (45 +/- 9 mIU/mL to 25 +/- 7 mIU/mL, p less than 0.05), not seen in the placebo group. Patients receiving zinc had an improvement in potency, libido, and frequency of intercourse not found in the placebo group. These results suggest that zinc deficiency is a reversible cause of gonadal dysfunction in patients having regular hemodialysis.

Lymphocyte and granulocyte function in zinc-treated and zinc-deficient hemodialysis patients

Lymphocyte blast transformation and granulocyte motility were studied in 20 clinically stable hemodialysis patients, 10 of whom were receiving 50 mg of zinc (as zinc acetate) per day and 10 of whom were not. Plasma zinc concentration was significantly higher in zinc-treated than in untreated patients (108 +/- 5 vs. 82 +/- 2 micrograms/dl). Mononuclear cell subpopulation analysis showed equivalent proportions of T lymphocytes and monocytes in both groups, but B lymphocytes were reduced in untreated patients (10 +/- 0.7 vs 14 +/- 0.5%). Lymphocyte blast transformations in response to nonspecific mitogens, soluble antigen and mixed lymphocyte culture were not significantly different in the two groups, nor was lymphocyte zinc concentration. Zinc-treated patients showed significantly greater granulocyte responsiveness to zymosan-activated serum (21 +/- 1 vs. 14 +/- 2 mean), greater chemokinetic activity (50 +/- 4 vs. 27 +/- 3 mean) and higher granulocyte zinc concentration (114 +/- 6 vs. 47 +/- 2 micrograms/10(6) cells) than untreated patients. Granulocyte zinc correlated significantly with plasma zinc (r = 0.81, P less than 0.001) and with granulocyte motility (r = 0.63, P = 0.001). Moderate zinc deficiency in hemodialysis patients does not result in abnormal lymphocyte blast transformation in vitro, but it does result in granulocyte zinc depletion and impaired granulocyte motility.

Long survival in sickle cell anemia

Ten patients with sickle cell anemia surviving beyond the age of 40 were compared to 11 subjects with sickle cell anemia who died before that age. Hematologic and biochemical data as well as clinical and physical parameters of the two groups were compared. There was no statistically significant difference between the two groups with respect to the degree of anemia, severity of hemolysis, or hemoglobin A2 levels. A statistically significant difference was found between the two groups with respect to fetal hemoglobin, red cell zinc, and secondary sexual characteristics. Although the long survivors had fewer crises per year than the short survivors, the long-term complications such as leg ulcer, congestive heart failure, and aseptic necrosis of the hip were more common in the older patients. Cerebrovascular accidents were the cause of death in 9/11 short survivors and are absent in the long survivors. The alpha/beta chain synthesis ratio was normal in the long-survivor group and alpha gene mapping in five subject in that group revealed the genotype alpha alpha/alpha alpha in four and -alpha/alpha alpha in one. The older patients as a group had higher red cell zinc values. The secondary sexual characteristics were also better developed in the older subjects. The overall significance of zinc status and of a higher HbF on longevity of sickle cell anemia patients remains unknown.

Zinc in plasma, neutrophils, lymphocytes, and erythrocytes as determined by flameless atomic absorption spectrophotometry

Zinc is determined in neutrophils and lymphocytes (isolated from whole blood on discontinuous gradients of Ficoll-Hypaque) and in microliter quantities of plasma and erythrocytes by flameless atomic absorption spectrophotometry with greater sensitivity than with conventional flame atomic absorption spectrophotometry. Before analysis, neutrophils and lymphocytes are digested with nitric acid and diluted with de-ionized water. Plasma and erythrocytes required no digestion, only dilution. Overall CVs were 4.0, 3.0, 5.0, and 4.6% for neutrophils, lymphocytes, erythrocytes, and plasma, respectively. Matrix effects were fully compensated for by use of standard solutions that simulated the sample matrix. Results for plasma and erythrocytes agreed with those obtained by the conventional technique.

Zinc in plasma, neutrophils, lymphocytes, and erythrocytes as determined by flameless atomic absorption spectrophotometry

Zinc is determined in neutrophils and lymphocytes (isolated from whole blood on discontinuous gradients of Ficoll-Hypaque) and in microliter quantities of plasma and erythrocytes by flameless atomic absorption spectrophotometry with greater sensitivity than with conventional flame atomic absorption spectrophotometry. Before analysis, neutrophils and lymphocytes are digested with nitric acid and diluted with de-ionized water. Plasma and erythrocytes required no digestion, only dilution. Overall CVs were 4.0, 3.0, 5.0, and 4.6% for neutrophils, lymphocytes, erythrocytes, and plasma, respectively. Matrix effects were fully compensated for by use of standard solutions that simulated the sample matrix. Results for plasma and erythrocytes agreed with those obtained by the conventional technique.

Renal handling of zinc: effect of cysteine infusion

Zinc clearance studies in anesthetized dogs were performed during hydropenia, mannitol infusion, and infusion of mannitol plus ZnSO4, ZnCL2, or cysteine. Mannitol expansion caused no significant change in Zn clearance. ZnSO4 infusion increased filtered Zn 13-fold without changing clearance. Zn excretion increased only sixfold, indicating increased net Zn reabsorption. Cysteine infusion increased urinary Zn excretion 86-fold, indicating net tubular Zn secretion, some of which derived from nonplasma sources. Stop-flow studies localized Zn reabsorption to the distal nephron during infusion of mannitol and mannitol plus ZnSO4 or ZnCl2. Net Zn secretion was shown to occur in the proximal tubule during cysteine infusion with reversal of the distal reabsorption pattern seen during ZnSO4 and ZnCl2 infusion. Despite increased urinary Zn excretion during ZnSO4 infusion, calcium excretion was unaltered. During cysteine infusion dissociation of tubular handling of CA2+ and Zn occurred in both the proximal and distal tubule. These experiments demonstrate that the nephron under these experimental conditions is capable of both proximal secretion and distal reabsorption of Zn.

Abnormal dark adaptation in sickle cell anemia

Patients with sickle cell anemia may be zinc-deficient. Zinc deficiency has been reported to cause delayed dark adaptation. We have studied dark adaptation in 13 patients with homozygous sickle cell anemia. Six patients had delayed dark adaptation. Their mean plasma and neutrophil zinc levels were 93.83 +/- 8.26 micrograms/100 microliters and 37.33 +/- 11.88 micrograms/10(10) cells, respectively, compared to the corresponding mean values for seven patients with normal dark adaptation of 105.86 +/- 13.31 and 86.71 +/- 19.53. For the six patients with delayed dark adaptation, the lower neutrophil zinc value, but not the plasma value, was significant (p less than 0.01). Three of the six were treated with oral zinc, with improvement in their dark adaptation. Neutrophil zinc levels correlated inversely (r = -0.77, p less than 0.01) with log relative threshold at 30 min. We conclude that patients with sickle cell anemia may show decreased ability to dark-adapt that is related to zinc deficiency.

Effect of zinc supplementation on serum testosterone level in adult male sickle cell anemia subjects

Previously, we have documented primary testicular failure in adult male subjects with sickle cell anemia. We have also reported the occurrence of zinc deficiency and suggested that androgen deficiency may be related to zinc deficiency in such patients. In this study, we present data with respect to the efferent of oral zinc supplementation on serum testosterone levels in adult male patients with sickle cell anemia. An increase in serum testosterone, neutrophil zinc, and neutrophil alkaline phosphatase activity ws observed in the zinc-supplemented group in comparison with the group on placebo. Additionally, body weight increased and serum lactic dehydrogenase activity decrease in response to zinc supplementation. We conclude that androgen deficiency in adult male subjects with sickle cell anemia is correctable with zinc supplementation and that the determination of neutrophil zinc and alkaline phosphatase activity in the neutrophils may be utilized as good indicators of body zinc status in such subjects.

Experimental zinc deficiency in man. Effect on testicular function

Dietary zinc intake was restricted (2.7 to 5.0 mg daily) for 24 to 40 weeks in five male volunteers. Their mean age was 57 years. Oligospermia (total sperm count less than 40 million per ejaculate) was induced in four out of five subjects. A decrease in the sperm count occurred during zinc restricion and the early phase of zinc repletion before body stores of zinc were restored to normal. The duration of oligospermia in the four subjects ranged from 6 to 14 months. Oligospermia was reversed after zinc supplementation in physiologic amounts. The baseline sperm concentration and total sperm count per ejaculate in all five subjects dropped significantly (p < 0.05) after zinc restriction and returned to normal 6 to 12 months after zinc supplementation. The decrease in sperm count coincided with decline in Leydig cell function and was reversed after zinc supplementation in low doses. Our study has demonstrated that dietary restriction of zinc can affect testicular function adversely. This effect of zinc deficiency, however, is a reversible process and can be corrected by proper supplementation with zinc.

Improvement of uremic hypogeusia by zinc: a double-blind study

Diminished taste acuity may account for the persistence of protein and caloric malnutrition observed in a majority of hemodialysis patients inspite of liberalization of the prescribed amount of dietary protein. Twenty-two patients undergoing thrice weekly hemodialysis for more than 6 months were tested for taste acuity and plasma zinc concentration, after which a double-blind study was instituted using a zinc supplement (50 mg of elemental zinc as zinc acetate per day) or a placebo. The threshold of taste detection and recognition for salt (NaCl), sweet (sucrose), and bitter (urea) but not for sour (HCl) improved significantly in all patients on zinc supplementation. None of these parameters improved in those taking placebo. During the study period, the mean plasma zinc level increased from 75 +/- 8 to 97 +/- 10 microgram/dl (P less than 0.001) in patients receiving zinc acetate. There was not significant change in plasma zinc level in the placebo group (75 +/- 15 to 80 +/- 15). The results of this study show that uremic hypogeusia improved in association with zinc supplementation and elevation of plasma zinc concentration.

Effect of zinc on hyperammonemia in sickle cell anemia subjects

An increase in plasma ammonia level in human volunteers on restricted zinc intake, and in zinc-deficient rats, has recently been reported. Inasmuch as zinc deficiency has been observed in sickle cell anemia patients, we measured plasma ammonia levels in such subjects. In this report we document hyperammonemia in sickle cell anemia patients that was corrected with zinc therapy.

Zinc metabolism in uremia

Subnormal plasma zinc levels have been reported in uremic patients. However, detailed studies regarding zinc status in uremia are not available. Twenty-five patients with chronic renal failure (10 undergoing maintenance hemodialysis, five receiving chronic peritoneal dialysis, and 10 nondialyzed azotemic patients) had lower concentration of zinc in plasma, leukocytes, and hair as well as increased plasma ammonia and ribonuclease activity compared to age- and sex-matched controls (p less than 0.001). Similar biochemical changes have been reported in experimentally induced zinc deficiency in both animals and man, except that erythrocyte zinc concentration was elevated in these patients. High erythrocyte zinc concentration may be related to ineffective erythropoiesis in uremia. The results of this study suggest that abnormality in zinc metabolism occurs commonly in patients with chronic renal failure and that it develops prior to initiation of dialysis treatment.

Deoxythymidine kinase activity of human implanted sponge connective tissue in zinc deficiency

The activity of deoxythymidine kinase was assayed in implanted sponge connective tissue in three groups of subjects: 1) five normal controls (having normal levels of plasma and red cell zinc); 2) four patients with sickle cell anemia who had low zinc in red cells and hair; and 3) two volunteers (under strict dietary controls), after 6 mo of zinc restriction (2.7 mg/day) and repeated after 3 mo of zinc repletion (30 mg/day). Total protein, total collagen, RNA/DNA, and deoxythymidine kinase activity were measured by techniques reported previously. In sickle cell anemia patients, deoxythymidine kinase activity was not detected, and RNA/DNA, total collagen, and total protein contents were decreased compared to normal controls (statistically significant). In human volunteers deoxythymidine kinase activity was not detected during the zinc restriction phase. After supplementation with zinc, deoxythymidine kinase activity became 70% of normal control levels, and RNA/DNA, total collagen, and total protein contents of sponge connective tissue increased. In conclusion, an adverse effect of zinc deficiency on deoxythymidine kinase activity of implanted sponge connective tissue of man has been demonstrated for the first time.

Hypocupremia induced by zinc therapy in adults

Hypocupremia occurred in an adult with sickle cell anemia who received zinc as an antisickling agent for two years. The hypocupremia was associated with microcytosis and relative neutropenia. Administration of copper resulted in an increase in RBC size and leukocyte counts. We have since observed hypoceruloplasminemia of varying degrees in several other sickle cell anemia patients who were receiving oral zinc therapy. This complication was easily corrected by copper supplementation.

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.

Plasma ammonia and liver ornithine transcarbamoylase activity in zinc-deficient rats

The effects of zinc deficiency on the activity of hepatic ornithine carbamoyltransferase (OCT) and plasma ammonia were studied in rats. One group received (ad libitum) zinc-deficient diet containing 2 ppm zinc and the other group received a diet containing 110 ppm zinc (group pair-fed control) equal to the amount consumed by zinc-deficient rats during the previous 24 h. Rats were killed at weekly intervals. Blood urea nitrogen (BUN), plasma ammonia, and hepatic OCT activity were determined. By end of the 1st wk on zinc-deficient diet, the plasma ammonia levels became significantly higher than those of the controls and remained elevated thoughout the study period. BUN increased initially for 2 wk in the deficient rats, but by the end of 4 wk the levels were lower than in the controls. The hepatic OCT activity in deficient animals was significantly lowered as compared to the controls by the 3rd wk. It is concluded that an increase in plasma ammonia may occur as a result of deficiency of zinc.

Suppression of irreversibly sickled erythrocytes by zinc therapy in sickle cell anemia

Zinc administered orally to 12 patients with SCA decreased the mean number of circulating ISC's from 28.0% before treatment to 18.6% during treatment. Seven of the 12 patients had statistically significant individual decreases in ISC counts, and two others had moderate reduction in ISC's of borderline significance. Patients who did not have a significant decrease in ISC count while on zinc therapy had low counts initially. The decrease in ISC's may mean improved oxygenation. The decrease in ISC's provides objective evidence of an in vivo effect of oral zinc treatment in SCA. The role of ISC's in the pathology and symptomatology of SCA is unknown, but some evidence suggests that ISC's may be related to vascular and organ damage. If so, therapies which decrease ISC counts, such as zinc, have the potential of reducing organ damage.