Control of in vitro lymphocyte proliferation by copper, magnesium and zinc deficiency

Plant lectin-induced proliferation of lymphocytes in vitro in both whole-spleen cell and T cell-enriched cultures was markedly effected by depletion of media copper, magnesium or zinc. The T lymphocyte-oriented mitogens concanavalin A and phytohemagglutinin and the B lymphocyte-oriented mitogen lipopolysaccharide were used to study variations in [3H]thymidine incorporation in lymphocytes cultured in media deficient in one mineral element. Since the stimulatory action of these mitogens also relates to the interaction of lymphocytes with accessory cells, we looked at the phagocytic ability of accessory cells cultured in the depleted media. In addition, we determined the variations in cell surface markers for B lymphocytes (Ia), T lymphocytes (Thy 1.2, Lyt 1 and Lyt 2) and accessory cells (Ia). Media depleted of copper, magnesium or zinc did not support normal T-lymphocyte proliferation but did support normal B-lymphocyte proliferation. The phagocytic ability of magnesium-deficient and zinc-deficient accessory cells was also depressed. This was related to depressed Ia expressions in the magnesium-deficient and zinc-deficient whole-spleen cell cultures. Total T-lymphocyte numbers, as well as Lyt 1+ cell percentages, were unchanged by media depletion, whereas Lyt 2+ cell percentages were depressed in both copper-deficient and magnesium-deficient splenocyte cultures.     

乙体氯氰菊酯对雄性大鼠脾脏T淋巴细胞增殖功能的影响

应用NTT法检测乙体氯氰菊酯对雄性大鼠脾脏T淋巴细胞增殖功能的影响,并测定大鼠体重和主要脏器系数。结果表明,该药致大鼠脾脏T淋巴细胞增殖功能明显降低,肾上腺系数明显增大。     

Release of zinc from maternal tissues during zinc deficiency or simultaneous zinc and calcium deficiency in the pregnant rat

Earlier studies have shown that diets that increase tissue catabolism reduce the teratogenic effects of zinc deficiency. The hypothesis that zinc may be released from body tissues when the metabolic state is altered was further tested. Nonpregnant Sprague-Dawley females were injected with 65Zn; after equilibration, the two major pools of zinc, bone and muscle had different specific activities, muscle being much higher. Females were mated and fed diets adequate in zinc and calcium, deficient in zinc alone or deficient in both zinc and calcium. Calculations using weight loss, zinc content of maternal bone and muscle and total zinc content of the fetus at term indicated that most of the zinc in the fetus at term in both the zinc-deficient and zinc-calcium-deficient groups came from breakdown of maternal muscle in the last 3 d of pregnancy. The relatively small amount of additional zinc released from bone in the zinc-calcium-deficient rats early in pregnancy was sufficient to prevent abnormal organogenesis. Specific activity of zinc in the zinc-deficient and zinc-calcium-deficient fetuses was equal and high, indicating that most zinc in these fetuses came from maternal tissues and from the same maternal sources in both groups. In contrast, specific activity of zinc in the fetuses from rats fed adequate zinc and calcium was less than 30% of that in either of the deficient groups; this is consistent with the hypothesis that most zinc accrued by these fetuses came directly from the diet.     

The effect of zinc deficiency on prostaglandin synthesis in rat testes

The effect of zinc deficiency on prostaglandin synthesis in rat testes was determined by feeding three groups of rats egg white-based semipurified diets. One group (ZD) was fed a zinc-deficient diet and two control groups were pair-fed (PF) or fed ad libitum (AL) a zinc-sufficient diet. The concentration (nanograms/gram) of the prostacyclin metabolite, 6-keto-prostaglandin-F1 alpha (6-keto-PGF1 alpha), in the tunica homogenate was significantly lower in ZD than in PF and AL groups. However, there was no difference when 6-keto-PGF1 alpha concentration was expressed as nanograms/milligrams of tunica protein. Tunica PGE2 concentrations (nanograms/gram) were not significantly altered by zinc deficiency. Concentrations of prostaglandins (PGs) in testis parenchyma were slightly higher in ZD probably as a result of increased levels of the precursor, arachidonic acid (AA). There was a highly significant correlation between PGE2 and AA in parenchyma phospholipids. PG synthesis was much greater in the tunica than in the parenchyma and prostacyclin appeared to be the major PG synthesized in both the tunica and parenchyma. It was concluded that PG synthesis is altered in the testes of zinc-deficient rats probably due to changes in concentrations of protein in the tunica and AA levels in parenchyma lipids.     

The effects of zinc deficiency on turnover of cadmium-metallothionein in rat liver

The object of this experiment was to determine the effects of Zn deficiency on the turnover of Cd-induced metallothionein (MT) in rat liver. Male rats were fed a purified Zn-deficient or Zn-adequate diet. After 13 days, the rats were given three daily injections of Cd2+ totaling 1.5 or 3.0 (Zn-deficient) and 3.0 or 6.0 (Zn-adequate) mg Cd/kg body weight. The MT was labeled by injecting the rats with [35S]cystine 2 hours after the final Cd injection. One, 3 or 5 days after labeling, the rats were killed, and their livers were assayed for MT 35S and metal content. The metal composition of MT (mole %) was 41-42% Cd, 51-54% Zn and 4-7% Cu in the Zn-adequate groups and 64% Cd, 27-31% Zn and 6-9% Cu in the Zn-deficient groups. The half-lives of Cd-induced MT in the Zn-deficient rats were 2.6 days (1.5 mg Cd/kg) and 2.8 days (3.0 mg Cd/kg). In the Zn-adequate rats, the half-lives were 3.6 days (3.0 mg Cd/kg) and 3.1 days (6.0 mg Cd/kg). The half-lives of general, soluble hepatic proteins were 4.1 to 4.3 days in all groups. Despite the stabilizing effect of the higher Cd content, the half-life of hepatic MT in the Zn-deficient rats was significantly shorter than in the Zn-adequate rats. These results indicate that hepatic MT degradation is faster in Zn-deficient animals.     

Effect of zinc deficiency on intestinal transport triglyceride in the rat.

Ultrastructural and biochemical changes in the intestinal epithelium during the process of active triglyceride absorption were studied in rats fed a zinc-deficient diet as compared with those of pair-fed and ad libitum-fed zinc-supplemented controls. The rate of triglyceride absorption markedly decreased in zinc-deficient rats. Despite a significant reduction in pancreatic lipase activity, the digestion of triglycerides proceeded normally in the zinc deficient rats, as evidenced by no apparent signs of diarrhea (or steatorrhea) and by the appearance of the hydrolytic products such as free-fatty acids and monoglycerides in the intestinal mucosa. The mucosa uptake of digested lipids and resynthesis of triglycerides in the mucosa from deficient rats were normal. Ultrastructural and chromatographic analysis of the mucosal lipids indicated a massive accumulation of lipid droplets, predominantly in the form of triglycerides. The primary defect in lipid absorptive processes in zinc-deficient rats occurred in the formation of chylomicrons. The lipid droplets in the mucosa of deficient rats were physically unstable. This instability was shown by coalescence of droplets which did not appear to be membrane-bound. Coalescing lipid droplets ranged from 2.0 to 4.0 micron in diameter. The absorptive cells were not able to discharge lipid droplets of this size into the intercellular spaces and hence into the lamina propria, resulting in the accumulation of the large droplets within the mucosa. This exit block to the movement of lipid droplets out of the mucosal cell appeared to be due to the failure, in zinc-deficiency, of the mucosal synthesis of proteins required for the formation of chylomicrons. Ultrastructural observations demonstrated changes in the subcellular organelles related to protein synthesis, including a marked reduction in granular endoplasmic reticulum and a quiescent appearance of the Golgi-complex.     

Effects of marginal zinc deficiency on subclinical lead toxicity in the rat neonate

Influence of maternal dietary zinc intake on tissue distribution of lead and zinc in neonatal rats administered lead acetate by gavage during lactation was examined. Milk from dams fed a marginally deficient diet (6 micrograms Zn/g diet) contained a lower zinc concentration at the beginning of lactation than did that from control dams (30 micrograms Zn/g diet); no differences were seen by d 11 of lactation. Dams fed the deficient diet had lower plasma zinc values in comparison with pair-fed or ad libitum-fed dams and lower femur zinc concentration in comparison with pair-fed dams. Pups suckling marginally deficient dams had lower concentrations of zinc in plasma, femurs and kidneys although hippocampal and cerebellar zinc were unaltered. Body weights of pups from marginally zinc-deficient dams were lower than those from ad libitum-fed dams, but similar to those from pair-fed dams. Lead ingestion had no effect on body weight. Marginally zinc-deficient pups had greater lead accumulation in blood, femurs, hippocampi and cerebella, but not kidney, than did zinc-adequate pups. Marginal zinc deficiency during lactation increases the body lead burden of suckling rats, an effect not attributable to increased transfer of lead into milk in response to suboptimal maternal zinc status.     

Effect of zinc deficiency on muscle fibre type frequencies in the post-weanling rat

Male weanling rats were maintained on diets either deficient or adequate in zinc for a period of 4 weeks. The rats on the deficient diet showed a reduction in food intakes and growth. After 4 weeks both soleus muscles and the lateral portion of the diaphragm were studied histochemically to examine the relative frequencies of the fibre types. The soleus muscles of the deficient animals showed a significant change in the proportion of slow and fast fibres. The diaphragm muscles of the deficient animals had a significant increase in the proportion of fast-twitch oxidative glycolytic fibres and a significant decrease in fast-twitch glycolytic fibres compared with the controls. Stainable lipid increased in the diaphragm muscle of the deficient animals with respect to their pair-fed controls.     

Plasma whole blood and urine zinc in the assessment of zinc deficiency in the rat

Serial measurements of plasma, whole blood, and urine zinc have been made in young adult rats fed zinc deficient and zinc supplemented diets for a total period of 65 days. After commencing a zinc deficient diet plasma zinc fell within 48 hours to 25% of control values and remained at this level throughout the period of study. A substantial diurnal variation was observed in plasma zinc, and the level was significantly lower in the fasting state. Whole blood zinc was unaffected by fasting, showed no diurnal variation, and remained at control values even after 65 days of zinc deficient diet. Urine zinc fell to very low values, 10 days after commencing a zinc deficient diet, but after 30 days rose to control values. Under controlled conditions plasma zinc can be used as an indication of zinc deficiency. Whole blood zinc is of no value in the detection of zinc deficiency. Urine zinc concentration varies with time following a zinc deficient diet.     

不同水平锌缺乏对大鼠胚胎心脏发育的影响

目的 探讨缺锌对大鼠胚胎心脏的发育毒性及其作用阈剂量和荆量-效应关系.方法 50只健康清洁级SD雌性大鼠,随机分成5组:1极低锌组,2低锌组,3中等低锌组,4边缘低锌组,5常锌组,分别饲以不同含锌量的饲料.锌耗竭性饲养25天后交配,孕第19天时活杀取胚鼠,通过切片观察胚胎心脏畸形情况.结果 各低锌组血锌值和血清碱性磷酸酶活性显著低于常锌组(血锌比较,t值分别为49.44、27.92、21.10、8.14,均P<0.05;血清碱性磷酸酶比较,t值分别为86.79、52.37、38.32、13.35,均P<0.05).同等条件下血清碱性磷酸酶活性变化更为明显.极低锌组、低锌组和中等低锌组与常锌组相比,胚心畸形率均明显增高(X2分别为35.62、16.93、5.91,均P<0.05);边缘低锌组与常锌组间比较则无显著性差异X2=0.00,P>0.05).胚心畸形主要表现为发育延迟、心房缺如、室间隔缺损、心室缺损等.结论 血清碱性磷酸酶活性是反映体内锌水平的敏感指标,与血锌值结合能较准确地反映体内的锌水平.母体中等以上低锌能增加胚心畸形的发生,孕鼠低锌对胚胎的毒性作用存在较明显的剂量-效应关系.     

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.     

Vitamin B-6 deficiency impairs interleukin 2 production and lymphocyte proliferation in elderly adults

The effect of vitamin B-6 deficiency on immune response was studied in eight healthy elderly adults. The protocol consisted of a 5-d baseline (BL) period; a vitamin B-6-depletion period of less than or equal to 20 d; three stages of vitamin B-6-repletion, each lasting 21 d; and a 4-d final phase. The amounts of vitamin B-6 ingested during the different phases of the study were 3.00, 15.00, 22.50, and 33.75 micrograms.kg body wt-1.d-1, respectively. During the final phase the subjects ingested 50 mg vitamin B-6/d. Fasting blood was collected at the end of each period. Vitamin B-6 depletion significantly decreased percentage and total number of lymphocytes, mitogenic responses of peripheral blood lymphocytes to T- and B-cell mitogens, and interleukin 2 production. These indices returned to BL values after the third vitamin B-6-repletion period, when the total vitamin B-6 intakes were 1.90 +/- 0.18 mg/d for women and 2.88 +/- 0.17 mg/d for men. Vitamin B-6 deficiency impairs in vitro indices of cell-mediated immunity in healthy elderly adults. This impairment is reversible by vitamin B-6 repletion.     

Effect of chloroquine on human lymphocyte proliferation

The effect of chloroquine on human blood mononuclear cells was studied. High concentrations of chloroquine in vitro profoundly suppressed the proliferation of mitogen- and antigen-stimulated cells, as indicated by decreased 14C-thymidine incorporation. Lower concentrations of chloroquine increased the response to pokeweed mitogen. The response to concanavalin A and to various antigens was suppressed, especially the response to large particulate antigens. Oral intake of 300 mg of chloroquine base/week did not affect the lymphocyte proliferative responses. 600 mg of base/week decreased the response to large particulate antigens; the response to small antigens was not affected. The mode of action of chloroquine and the possible consequences of the findings for dosage of chloroquine when used for malaria prophylaxis is discussed.     

Response of submandibular gland of the rat to nutritional zinc deficiency.

Studies in several laboratories have shown that nutritional Zn deficiency in the rat causes a reduction in the activity of certain Zn-dependent enzymes in kidney, intestine, pancreas, etc. The present report deals with the effects of Zn-deficiency on submandibular gland of the rat. For the sake of comparison with previous studies, some assays on pancreas were included. Protein content, DNA, acid phosphatase, and acid protease activities were not affected in submandibular gland. Lactate dehydrogenase was unaffected in submandibular gland and showed increased activity in pancreas. Malate dehydrogenase was significantly decreased in both organs, the decrease being more marked in submandibular gland. Alkaline phosphatase activity in submandibular glands of control rats was about 10-fold higher than in pancreas. In the zinc-deficient rats, alkaline phosphatase was reduced to 59% of controls in the submandibular glands and to about 75% in pancreas. It is known from histochemical studies that in the submandibular gland this enzyme is confined to the myoepithelial cells. Recent studies attribute to salivary glands a role in the etiology of taste disturbances seen in clinical states of zinc deficiency. It is proposed that functional impairment of the myoepithelial cells might contribute to the disturbance of taste.     

Use of EDTA to produce zinc deficiency in the pregnant rat.

The effectiveness of EDTA in reducing the endogenous zinc supply in pregnant rats was determined by two experiments. In experiment 1, a high level of zinc (100 ppm) was given to rats days 15 through 17 of gestation. In experiment 2, a low level of zinc (3 ppm) was given from days 1 through 17. On day 18, half the rats were given EDTA in two intraperitoneal injections 6 hours apart with or without zinc supplementation. The -Zn + EDTA group lost weight continuously after the injections, had increased hematocrit levels prior to parturition,and showed greater stress at parturition than did the -Zn group. Weight gains, hematocrit level, and parturition in the +Zn + EDTA group did not differ significantly from those of the +Zn controls. Spleen weights were decreased in the -Zn + EDTA and -Zn groups and zinc concentration in the spleen increased in the -Zn + EDTA group. Iron concentration decreased in the spleen and increased in the liver of EDTA-treated rats. Use of EDTA to remove endogenous zinc appears to offer a mechanism for study of the effects of short-term zinc supplementation at critical periods in the pregnant zinc-deficient rat.