Effects of metal ions on cyprinid fish immune response: in vitro effects of Zn2+ and Mn2+ on the mitogenic response of carp pronephros lymphocytes

Lymphocytes from the pronephros of carp (Cyprinus carpio L) have been subjected to transformation by mitogens, concanavalin A (Con A), phytohemagglutinin (PHA), and lipopolysaccharides (LPS), with Zn or Mn at varying concentrations. Addition of Zn2+ (10(-7) to 10(-3) M) to mitogen-stimulated T and B cells enhanced [3H]thymidine incorporation. Addition of 10(-5) M Zn2+ inhibited the response to Con A, PHA, and LPS. At this concentration, Zn was toxic. Addition of Mn2+ (10(-7) to 10(-3) M) to mitogen-stimulated lymphocytes enhanced [3H]thymidine incorporation. This effect was observed with Con A- and PHA-stimulated lymphocytes, but not with LPS-stimulated lymphocytes. In contrast, addition of 10(-1) M Mn2+ to lymphocyte cultures exerted an inhibitor on the response to Con A or to PHA, while the response to LPS was unaffected. Addition of 10(-1) M Mn2+ to Con A- or PHA-stimulated cultures at different times after initiation of stimulation indicated that Mn2+ was inhibitory only when it was added before the first 16 hr of cultures. The inhibition induced by 10(-1) M Mn2+ could be reversed by adding 2 mM CaCl2 to the culture.     

Depressed transformation response by splenic lymphocytes from vitamin A-deficient rats

Concanaval in A (Con A)-stimulated lymphocytes isolated from the spleen of vitamin A-deficient rats showed decreased [³H]thymidine incorporation compared to pair-fed and ad libitum-fed controls. This decrease was evident over a range of Con A concentrations (1–7 μg/ml), and the mitogen concentration which elicited maximum response was the same (2 μg/ml) for all three dietary groups. A three-day in vivo repletion with retinyl acetate led to recovery of normal or greater than normal [³H]thymidine incorporation at all concentrations of Con A. At time intervals when DNA synthesis was significantly increased by Con A (48, 72 and 96 hours after stimulation) the [³H]thymidine incorporation by vitamin A-deficient lymphocytes was always lower than that of pair-fed and ad libitum-fed controls. Decreased splenocyte blastogenesis was also demonstrated for the B-cell mitogen E. coli lipopolysaccharide, which was not completely accounted for by reduced numbers of B-cells in the spleen of vitamin A-deficient rats.     

Effect of protein malnutrition and interleukin 1 on in vitro rabbit lymphocyte mitogenesis

Chronic protein calorie malnutrition has been shown to depress T lymphocyte proliferation responses to mitogen and to attenuate interleukin 1 (IL-1) production by activated monocytes. We investigated the ability of rabbit monocyte-derived IL-1 to promote in vitro transformation of T lymphocytes obtained from protein and from calorie malnourished donors to mitogen. Protein deprivation produced a small, but statistically significant, decrease in [³H] thymidine incorporation to suboptimal (1.5 μg/mL) and optimal (2.5 μg/mL) concentrations of concanavalin A (Con A) in unfractionated produced a significant increase in proliferative responses to Con A in unfractionated cultures compared with controls. Addition of IL-1 partially purified supernatant, in a dose of 1% (final volume in culture), produced significantly greater enhancement of proliferation to Con A in lymphocyte cultures obtained from protein malnourished donors compared with controls, at both suboptimal (p<0.01) and optimal (p<0.01) concentrations of Con A. These results indicate that in control cultures with IL-1 already present in the system (presumably derived from monocytes in the culture), further supplementation with exogenous IL-1 has only a modest enhancing effect on lymphocyte proliferation to Con A. In cultures without IL-1 present (i.e., protein malnourished donors), supplementation with exogenous IL-1 markedly enhances lymphocyte proliferation to mitogen and reverses the T cell unresponsiveness to mitogen secondary to malnutrition.     

Effect of dietary ascorbic acid intake on tissue vitamin C in mice

The effect of graded levels of dietary ascorbic acid on blood and tissue ascorbic acid levels in mice has been studied. Six levels of dietary ascorbic acid (0, 0.076, 0.5, 1, 5 and 8%) were used. Plasma ascorbic acid rose as dietary ascorbic acid intake increased from 1 to 8%. Mice fed a diet with 5 or 8% added ascorbic acid had significantly higher levels of ascorbic acid in the heart, kidney, lung, muscle and spleen than did control mice fed an ascorbic acid-free diet. Mice fed a diet with 1% added ascorbic acid had elevated ascorbic acid levels in the heart, kidney, lung and spleen. No significant change was observed in ascorbic acid level in the brain, adrenal gland or leukocytes in any of the experimental groups. Ascorbic acid level in the eyes was only slightly higher in mice fed a diet containing 8% added ascorbic acid than in control mice. The observation that the kidney had the greatest increase in ascorbic acid content suggests that the kidney may be a very important organ not only in elimination but also in catabolism of this vitamin. A diet containing 0.5 or 0.076% added ascorbic acid did not significantly increase ascorbic acid content in any of the organs studied. Mice fed a diet with 0.076% added ascorbic acid had slightly, but statistically significantly, lower levels of ascorbic acid in the liver, lung, muscle and spleen that control mice. Mice fed a diet with 0.5% added ascorbic acid had a lower ascorbic acid content in the liver and muscle than the controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary leucine, alpha-ketoisocaproate and isovalerate on antibody production and lymphocyte blastogenesis in growing lambs

The chronic effects of oral leucine and leucine metabolites on sheep immune function were determined in two experiments. In replicate experiments, 30 mixed-breed ram lambs were individually fed diets supplemented with approximately 0.05% ruminally protected limestone (control), alpha-ketoisocaproate (KIC), isovalerate (IVA) or leucine (Leu). Serum titers of antibodies produced in response to Brucella abortus antigen and porcine red blood cells were determined. Mitogen-stimulated lymphocyte blastogenesis was determined in experiment 2 by adding phytohemagglutinin (PHA), concanavalin A (Con A) or pokeweed mitogen (PWM) to isolated lymphocytes and measuring [3H]thymidine incorporation. In both experiments, in lambs fed Leu, antibody production to porcine red blood cells was approximately 80% (P less than 0.05) of that in control animals. When KIC was fed, antibody titers to porcine red blood cells were approximately 120% (P less than 0.05) of that of controls. Compared to controls background lymphocyte blastogenesis was higher when KIC was fed, whereas background blastogenesis was lower when Leu was fed (KIC vs. Leu; P less than 0.05). IVA did not significantly affect either measurement. These data indicate that feeding Leu may adversely affect immune function by suppressing lymphocyte activity, whereas oral administration of KIC has a positive influence on immune function in sheep by increasing lymphocyte activity.     

Stopped flow ESR study of the action of carbohydrates on ascorbic acid oxidation in aqueous solution

The influence of added carbohydrate on the decay kinetics of the ascorbic acid free radical generated in deaerated aqueous solutions by the action of potassium ferricyanide on ascorbic acid has been studied. Addition of carbohydrate (less than or equal to 0.5M) generally leads to a small decrease in radical decay rate. In our system this probably arises from reduced reactant diffusion in solutions of increased viscosity rather than the preferential chelation previously suggested to explain inhibition in the copper (II) catalyzed oxidation. The ascorbic acid free radical shows negligible tendency to react with glucose, sorbitol or maltose. The decrease in its decay rate observed on addition of carbohydrate is probably caused by the increase in solvent viscosity.     

Alterations in immune function in rats caused by dietary lipotrope deficiency: effect of age

Weanling male Sprague-Dawley rats were maintained on a control (C), folacin-deficient (F) or marginal methionine-choline diet (M/C) for 3 weeks, 3 months or 12 months. The immunocompetence of the animals was determined by in vivo (response to infection with salmonella typhimurium) and in vitro (lymphocyte transformation assay) methods. It was found that young animals were most sensitive to dietary lipotrope deficiency, and the in vivo response to bacterial infection did not always correlate with in vitro assessment of immune function. Histopathologic examination of spleens from S. typhimurium-infected rats maintained for 3 weeks on the experimental diets showed an overall decreased cellularity especially in the follicular areas, compared to controls. No differences were seen in the spleens of infected animals at later time points. A short-term (3-week) lipotrope deficiency resulted in a depressed lymphocyte transformation response to concanavalin A (Con A) in the spleen, thymus and lymph nodes; to phytohemagglutinin A (PHA) in the spleen and lymph nodes only. After 3 months on the F or M/C diets, a depressed Con A-induced transformation response was still seen in the spleen, but the normal aging-induced immunosuppression resulted in a low response in all animals, with few significant differences existing among groups.     

Effect of ascorbic acid intake on tissue dehydroascorbic acid in mice

The effect of ascorbic acid intake on tissue levels of ascorbic acid, dehydroascorbic acid and the ratio of dehydroascorbic acid to ascorbic acid in mice was studied. In general, the trend of changes in tissue concentrations was: ascorbic acid > dehydroascorbic acid ratio of dehydroascorbic acid to ascorbic acid. Mice fed a diet with 1% ascorbic acid had significantly higher concentration of dehydroascorbic acid in the kidney, lung and spleen than did control mice fed an ascorbic acid-free diet. Mice fed a diet with 5% ascorbic acid had elevated levels of dehydroascorbic acid in the brain, kidney, liver, lung and spleen. The kidney and lung had the greatest increase in dehydroascorbic acid concentration, suggesting that these two organs may be important sites for catabolism and elimination of ascorbic acid. In comparison with the corresponding control values, the ratio of dehydroascorbic acid to ascorbic acid was higher in the lung, not different in the liver and spleen, and lower in the kidney of mice fed a diet with 1 or 5% added ascorbic acid. These ratios were higher in the brain of mice fed a diet with 5% added ascorbic acid than in mice fed the ascorbic-acid-free diet. No apparent physiological abnormality in these animals was observed. These effects were stereospecific. Exogenous erythorbic acid, D-isoascorbic acid, a stereoisomer of ascorbic acid, increased dehydroascorbic acid equivalents (the sum of dehydroascorbic and dehydroerythorbic acid) in the kidney, lung, and spleen but the ratios of dehydroascorbic acid plus dehydroerythorbic acid to ascorbic acid plus erythorbic acid were essentially unaffected. A large glucose intake (1 or 5% in the diet) did not have an effect on levels of tissue ascorbic acid or dehydroascorbic acid.     

Studies of immunomodulating actions of carotenoids. I. Effects of beta-carotene and astaxanthin on murine lymphocyte functions and cell surface marker expression in in vitro culture system.

The immunomodulating effects of carotenoids (beta-carotene and astaxanthin) on mouse lymphocytes were studied in in vitro culture system by use of assay for mitogen responses of spleen cells, thymocyte proliferation, interleukin 2 production, and antibody (Ab) production in vitro in response to sheep red blood cells. Changes of cell surface markers on spleen lymphocytes including Ia antigen (Ag), surface immunoglobulin, B220, and Thy-1 Ag were also examined. At a concentration of 10(-8) M, carotenoids did not show any significant effect on mitogen responses (phytohemagglutinin P and concanavalin A) on murine spleen cells, irrespective of the concentrations of mitogens used. Interleukin 2 production by murine spleen cells was not significantly altered by carotenoids in the culture media (10(-7) to 10(-9) M). [3H]thymidine incorporation by B6 thymocytes was somewhat enhanced in the presence of astaxanthin or beta-carotene when cultured in the concentration of 10(6)/ml. At higher concentrations of cells (5 x 10(6)/ml), such an effect was not observed. In assays of in vitro Ab production in response to sheep red blood cells, B6 spleen cells produced significantly more Ab-forming cells (plaque-forming cells, immunoglobulins M and G) in the presence of astaxanthin (greater than 10(-8) M) but not beta-carotene. Expression of Ia Ag seemed to be moderately enhanced on both Thy-1+ and Thy-1- spleen cells in the presence of astaxanthin (greater than 10(-9) M) but not beta-carotene. The expression of Thy-1 and surface immunoglobulin seemed unchanged with the treatment of these carotenoids. These results indicate that immunomodulating actions of carotenoids are not necessarily related to provitamin A activity, because astaxanthin, which does not have provitamin A activity, showed more significant effects in these bioassays and also indicate that such actions of carotenoid demonstrated in this study may be difficult to explain only by its oxygen-quenching capacity.     

Immunological evaluation of four arc welders exposed to fumes from ignited polyurethane (isocyanate) foam: antibodies and immune profiles

Four arc welders having a flu-like illness with multiple health complaints following an exposure to high concentrations of isocyanate fumes from ignited polyurethane foam underwent immunological tests as follows: ELISA antibody assays, activated lymphocyte profiles, and lymphocyte blastogenesis. ELISA procedures revealed the presence of antibodies to hexamethylene diisocyanate (HDI) and formaldehyde (F) conjugated to human serum albumin (HDI-SA and F-SA). The results from the activated lymphocyte profiles showed deviations from the norm as follows: three welders had elevated helper/suppressor (H/S) ratios; all four had elevated percentages of Tal positive cells; two had decreases in B cells; and one had low total white cell and lymphocyte counts. In contrast, the percentage and absolute numbers of ILS receptor cells were normal in the four subjects. T cell blastogenesis to PHA, Con A and PWM resulted in the following: T-cells from one subject responded normally; in another, a high response (212% of controls) to PHA occurred with normal mitogenesis to Con A and PWM. In the remaining two welders, the T cells responded abnormally low (50 to 75% of controls) to the three mitogens. In conclusion, the existence of IgG antibodies to HDI-SA and F-SA, the altered activated immune profiles, the elevated Tal cells, and the abnormal blastogenesis are interpreted as being linked with the episode of HDI and F exposure and the subsequent flu-like illness of the four welders.     

Mitogen stimulation of lymphocytes in CBA mice exposed to lead and cadmium.

CBA mice were exposed to lead acetate or cadmium chloride in drinking water for 10 weeks. Selected groups of these animals were also injected with Bacillus Calmette-Guerin (BCG) during exposure to the metals. The ability of mitogens concanavalin A (Con A) and lipopolysaccharide (LPS) as well as purified protein derivative (PPD) to induce proliferation of splenic lymphocytes was assessed. In general, lead tended to inhibit lymphocyte proliferation by LPS and PPD while cadmium potentiated blastogenesis by these mitogens. The two larger doses of cadmium, 30 and 300 ppm, resulted in intense proliferation which was significant (P < 0.05) for the non-BCG, 300-ppm cadmium group. However, 3 ppm cadmium reduced the lymphocyte response to LPS and PPD which was significant (P < 0.05) for the non-BCG-injected mice. Lead and cadmium did not significantly affect the response of lymphocyte proliferation by Con A. Group variation and interpretation of data are discussed.     

褪黑素对鞘内泵入吗啡致免疫功能抑制大鼠免疫功能的影响

目的本实验采用ALZET泵建立鞘内持续泵入吗啡所致的免疫功能抑制大鼠模型,腹腔注射褪黑素观察其对鞘内泵入吗啡大鼠免疫功能的影响。方法 32只SD大鼠随机分为4组：生理盐水组（NS组,n=8）、吗啡组（M组,10μg/h,n=8）,吗啡组＋褪黑素组（M＋MLT组,n=8）,吗啡组＋生理盐水组（M＋NS组,n=8）。用microspinal导管根据改良Yaksh法进行鞘内置管,连接ALZET泵,持续泵入吗啡、生理盐水,MLT组连续7 d腹腔注射褪黑素,每次时间点为7：00-9：00 am,5 mg/kg。M＋NS组连续7 d腹腔注射生理盐水。7 d后原代分离脾脏单个核细胞进行培养,采用3H-TDR（甲基3H胸腺嘧啶核苷）掺入法检测脾T淋巴细胞对刀豆蛋白（ConA）刺激诱导的增殖水平;乳酸脱氢酶（LDH）释放法检测脾NK细胞活性;流式细胞仪检测脾T淋巴细胞亚群（CD3＋、CD3＋CD4＋、CD3＋CD8＋、CD4＋/CD8＋）和NK细胞（CD161＋）表型变化。结果与NS组相比较,泵入吗啡7 d后M组T淋巴细胞增殖水平、NK细胞活性降低（P〈0.05）,M组CD3＋、CD3＋CD4＋、CD3＋CD8＋细胞数量及百分率降低,CD4＋/CD8＋降低,CD161＋降低（P〈0.05）;同M＋NS组比较,M＋MLT组T淋巴细胞增殖水平、NK细胞活性升高（P〈0.05）,M＋MLT组CD3＋、CD3＋CD4＋、CD3＋CD8＋数量及百分率升高,CD4＋/CD8＋升高,CD161＋升高（P〈0.05）。结论鞘内泵入吗啡（10μg/h）可明显抑制大鼠细胞免疫功能;褪黑素可改善鞘内泵入吗啡所致的免疫功能抑制大鼠细胞免疫功能。     

Effect of antioxidant vitamin supplementation on DNA damage and repair in human lymphoblastoid cells

In this study the possible protective effects of ascorbic acid and α‐tocopherol (singly and in combination) on Raji lymphoblastoid cells exposed to various doses of X‐rays or hydrogen peroxide (H₂O₂) are investigated. DNA strand breaks and alkali‐labile sites were measured using the alkaline comet assay. Survival and hypoxanthine gua‐nine phosphoribosyl transferase mutant frequency were measured using the colony‐forming assay. Ascorbic acid (60 μM) and α‐tocopherol (30 μM) were added singly or together to cell culture medium 24 hours before treatment and were present during treatment. After the 24‐hour supplementation period with ascorbic acid alone, α‐tocopherol alone, and ascorbic acid + α‐tocopherol, the level of endogenous DNA damage was significantly lower (p < 0.05) than in the nonsupplemented culture, as assessed by the comet assay. By use of the comet assay, it was observed that ascorbic acid exhibited an overall protective effect against DNA damage induced after X‐ray treatment, whereas α‐tocopherol exhibited an overall protective effect against DNA damage induced after H₂O₂ treatment. Significant increases were observed in the percent survival after 1‐Gy X‐rays and 5 and 20 μM H₂O₂ in those cultures supplemented with ascorbic acid alone and α‐tocopherol alone relative to the nonsupplemented cultures. The endogenous level of mutant frequency was also significantly decreased in the presence of ascorbic acid relative to the nonsupplemented culture. These findings are consistent with the concept that ascorbic acid and α‐tocopherol can, under certain conditions, protect against oxidatively induced DNA damage.     

Protective effect of ascorbic acid on the breakdown of proteins exposed to hydrogen peroxide in chicken skeletal muscle.

Ascorbic acid is believed to protect cells from oxidative damage by reacting with oxygen-derived free radicals. We investigated whether ascorbic acid would affect the rate of breakdown of skeletal muscle proteins in extracts exposed to hydrogen peroxide. Ascorbic acid (20 mmol/L) alone had little or no effect on the rate of ATP-independent or ATP-dependent breakdown of proteins in chicken skeletal muscle. Pretreatment of chicken skeletal muscle extracts with 10 mmol/L H2O2 resulted in a complete loss of ATP-dependent proteolysis and a significant increase (14- to 15-fold) in the rate of ATP-independent protein breakdown. Ascorbic acid (20 mmol/L) did not prevent H2O2 (10 mmol/L) from inactivating the ATP-dependent proteolytic pathway in skeletal muscle. However, ascorbic acid (20 mmol/L) prevented the H2O2-induced increase in the ATP-independent proteolysis of endogenous muscle proteins. Ascorbic acid also slowed the rate of hydrolysis of exogenously added [3H]superoxide dismutase exposed to H2O2 and inhibited the enhanced degradation of [3H]lysozyme and H2O2-treated [3H]superoxide dismutase by the proteolytic systems exposed to H2O2. Thus ascorbic acid seems to inhibit the H2O2-induced increase in ATP-independent proteolysis 1) by preventing damage to proteins by H2O2 resulting in a decreased supply of substrates for the ATP-independent degradative system and 2) by preventing activation of the proteolytic enzymes that participate in the energy-independent degradation of H2O2-treated proteins.     

Effects of dietary methionine, cystine and potassium sulfate on serum cholesterol and urinary ascorbic acid in rats fed PCB

Liver weight, liver and urinary ascorbic acid levels and serum cholesterol concentration were higher in rats fed polychlorinated biphenyls (PCB) than in controls. The influences of methionine, cystine and potassium sulfate on these metabolic responses were studied. Methionine or equivalent moles of cystine or potassium sulfate were added to a basal diet containing 10% soy protein isolate. The basal diet contained 0.3% of total sulfur-containing amino acids (S-AAs). When methionine was added to the basal diet, maximum gain in body weight was obtained with 0.5% of dietary S-AAs, while the highest values in serum cholesterol and urinary ascorbic acid were obtained with 0.8% of dietary S-AAs in rats fed PCB. Dietary addition of cystine had little effect on body weight gain. Nevertheless, in rat fed PCB, urinary ascorbic acid and serum cholesterol were significantly higher in rats fed the cystine-supplemented diet than in those fed the unsupplemented diet. Addition of potassium sulfate had no effect on body weight gain, urinary ascorbic acid or serum cholesterol. These results suggest that more S-AAs are required for the highest metabolic response to PCB than for maximum growth, and the higher requirement for S-AAs cannot be replaced by inorganic sulfate.     

硫芥诱导淋巴细胞凋亡与细胞周期的关系

目的 探讨硫芥诱导体外培养大鼠脾脏淋巴细胞凋亡及与细胞周期的关系。方法 体外分离培养大鼠脾脏淋巴细胞。以流式细胞仪、琼脂糖凝胶电泳分别检测细胞凋亡，细胞周期，和DNA片段改变。结果 硫芥可诱导淋巴细胞凋亡(P＜0．05)，对细胞周期有明显影响，主要是S期和G2／M期明显降低，引起淋巴细胞生长阻滞在Gl期；流式细胞仪PI染色出现亚二倍体峰(凋亡峰)，其Gl期DNA含量明显增加，S期含量减少；琼脂糖凝胶电泳呈典型的“梯状”带(DNA ladder)。结论 硫芥可抑制体外培养的淋巴细胞由Gl期进入S期，抑制体外培养的淋巴细胞增殖，通过诱导淋巴细胞凋亡实现作用机制。     

Effect of ascorbic acid on the absorption of zinc and calcium in man

The effect of ascorbic acid on the absorption of zinc and calcium, was studied in healthy subjects by a radionuclide technique with 65Zn and 47Ca and whole body retention measurements. Addition of 100 mg of ascorbic acid to a water solution of 40 or 200 mumol zinc and 1 g of ascorbic acid to a high phytate meal with wholemeal bread had no effect on zinc absorption. Neither did 1 g of ascorbic acid added to 6.4 mmol of calcium influence the retention and calculated absorption of calcium. The results suggest that ascorbic acid does not affect the absorption of normal dietary levels of zinc and calcium.     

Alpha-tocopherol and ascorbic acid decrease the production of beta-apo-carotenals and increase the formation of retinoids from beta-carotene in the lung tissues of cigarette smoke-exposed ferrets in vitro

Previously, we found that exposing ferrets to cigarette smoke enhanced oxidative excentric cleavage of beta-carotene. In the present study, we examined whether alpha-tocopherol, ascorbic acid, or the two combined can prevent smoke-altered beta-carotene metabolism. In vitro incubation of beta-carotene (10 micro mol/L) with lung postnuclear fractions from ferrets exposed to cigarette smoke was carried out in the absence or presence of alpha-tocopherol (50 micro mol/L), ascorbic acid (10 or 50 micro mol/L), or both vitamins to evaluate their effects on the production of beta-apo-carotenals and retinoids from beta-carotene. The oxidative cleavage metabolites of beta-carotene, beta-apo-carotenals (beta-apo-14', beta-apo-12', beta-apo-10', and beta-apo-8'), retinoic acid (RA), and retinal were analyzed by HPLC. We found that the smoke-enhanced production of individual beta-apo-carotenals was significantly decreased by 36-77% when alpha-tocopherol (50 micro mol/L) and ascorbic acid (50 micro mol/L) were added together to the incubation mixture. alpha-Tocopherol alone had a modest effect. Ascorbic acid in the presence of alpha-tocopherol inhibited the production of beta-apo-carotenals in a dose-dependent manner, although ascorbic acid alone had no effect. In contrast, the production of RA and retinal among smoke-exposed ferrets was substantially increased ( approximately 3-fold, P < 0.05) when both alpha-tocopherol and ascorbic acid were added to the incubation mixtures. However, when ascorbic acid or alpha-tocopherol alone was added, the production of RA among smoke-exposed ferrets increased only modestly (80%, P < 0.05) and did not differ from the RA levels in control ferrets. In conclusion, these data indicate that alpha-tocopherol and ascorbic acid may act synergistically in preventing the enhanced oxidative excentric cleavage of beta-carotene induced by smoking exposure, thereby facilitating the conversion of beta-carotene into RA and retinal.     

Long-term effectiveness of dietary iron and ascorbic acid in the prevention and cure of cadmium toxicity in rats.

The protective and curative effects of dietary iron and ascorbic acid on chronic (180 days) cadmium toxicity in rats were examined. Growth retardation and anemia were observed in rats fed a diet containing 50 ppm of cadmium for 180 days; during this period the contents of iron in the liver, kidney, spleen, testis, intestine, and tibia decreased and the zinc contents of the liver and kidney increased, but the calcium content of bone did not change. Addition of 400 ppm of iron and 1% of ascorbic acid to the cadmium-containing diet overcame the growth retardation and anemia due to cadmium toxicity and reduced the tissue levels of cadmium; however, it did not restore the zinc contents in the liver, kidney, and bone to normal. Similar effects were observed when these compounds were added to cadmium containing diet for 90 days after feeding the cadmium diet alone for 90 days. The glutamic-pyruvic transminase and glutamic-oxaloacetic transminase activities in the plasma of rats fed the cadmium diet increased significantly and these increases were prevented by supplementing the diet with iron and ascorbic acid. Glucose, urea, and alkaline phosphatase in the plasma and glycogen in the liver were not changed by feeding the cadmium diet for 180 days. These results indicate the long-term effectiveness of supplementing the diet with iron and ascorbic-acid for preventing and curing dietary cadmium toxicity in rats.     

Effects of nucleosides and a nucleotide on DNA and RNA syntheses by the salvage and de novo pathway in primary monolayer cultures of hepatocytes and hepatoma cells

Studies were made on the effects of inosine, guanosine 5'-monophosphate (GMP), cytidine, uridine, thymidine, and their mixture (4:4:4:3:1, OG-VI) on DNA and RNA syntheses in primary monolayer cultures of normal hepatocytes and cultures of hepatoma cells, AH130, to use these compounds for total parenteral nutrition. Addition of an appropriate amount of inosine, GMP, uridine, or thymidine to primary cultures of hepatocytes enhanced both DNA and RNA syntheses by the salvage and de novo pathways. Cytidine appeared to have lower optimal concentration for enhancing these pathways. The OG-VI mixture also enhanced the syntheses of DNA and RNA, but the composition of the mixture was not optimal. Additions of inosine, GMP, uridine, and thymidine to cultured hepatoma cells also enhanced their DNA and RNA syntheses, but the cells consumed more of the added nucleic acid compounds than hepatocytes did. Addition of cytidine had no effect on proliferation of the cells. The OG-VI mixture at relatively higher concentration inhibited the syntheses of DNA and RNA by hepatoma cells. Addition of high concentrations of nucleic acid compounds was found to suppress the proliferation of both hepatocytes and hepatoma cells. These results suggest that addition of optimal amounts of nucleic acid compounds such as nucleosides and nucleotides would enhance growth of hepatocytes, particularly during liver regeneration, but that they may also enhance proliferation of tumor cells in the liver.