Organ sequestration of 65Zn during experimental sepsis

Alteration in the metabolism of zinc during infections has been reported. We have studied the redistribution of endogenous zinc by making the animals physiologically stable by daily intra-gastric administration of 65Zn prior to the induction of sepsis. Organ uptake of exogenous zinc was studied by investigating the organ uptake of 65Zn after an intravenous injection during sepsis. Male Sprague-Dawley rats, were kept in metabolic cages to monitor the excretion of the radioisotope. They were made septic using a gelatine capsule containing E. coli, Bacteroides fragilis in a standardised mixture with sterile rat faeces and barium sulphate, implanted into the abdomen. The plasma radioactivity in the septic state was significantly lower when compared to control rats. In the septic state, there was an increased uptake of endogenous zinc after oral administration of radioactive zinc in the liver, pancreas, large intestine and testes. When administered intravenously in septic animals we found a decreased uptake of exogenous zinc in the pancreas, large intestine, small intestine, bone and testes. Thus the distribution of endogenous and exogenous zinc seems to differ during the septic state.

Dietary intake and bioavailability of trace elements

In order to assess the nutritional importance of trace elements, it is relevant to consider the factors regulating their metabolism. One of the most important factors is the true intake level. Conventional techniques such as diet history and interview studies in conjunction with standard food tables do not provide the true intake levels from prepared meals. Employing the duplicate portion technique, we have investigated the dietary intake of trace elements in prepared meals consumed by children, adults, and elderly in Sweden. The results indicate that the intake of potassium, magnesium, zinc, copper, and selenium is low when compared with the present recommended dietary allowance (RDA) values. It appears that a marginal deficiency of a number of trace elements may exist in the general population of affluent countries. When the dietary intakes are known, it is necessary to consider the bioavailability. This depends on the chemical form as well as the concentration of other dietary constituents such as fiber, phytate, carbohydrates, macrominerals, and vitamins in the diet. Knowledge of these interactions are important to improve the overall nutritional status of the population in general and patients in particular.

New aspects on the distribution and metabolism of essential trace elements after dietary exposure to toxic metals

Under present environmental conditions, an increase in pollution owing to metals such as cadmium (Cd), lead (Pb), and methylmercury (MeHg) must be expected. The resulting effects would be seen particularly in the food chain. The daily intake of toxic metals in various parts of the world is different and depends on both the dietary habits and the concentration in foodstuffs. Oral ingestion of these toxic metals perturbs the metabolism of essential elements, especially zinc (Zn), copper (Cu), iron (Fe), and selenium (Se). The elemental composition of body tissues and fluids is an indicator of the nutritional and pathological status of humans. This review will describe the dietary intake and gut absorption of essential and toxic elements. Furthermore, it will discuss threshold values, toxic effects in relation to body burden of toxic metals, the biological indices of exposure, and the interaction between toxic and essential elements. The overall ratio of Cu, Zn, Fe, and Se concentration to Cd in the human kidney is the lowest in comparison to Hg and Pb. Increased kidney copper and urinary losses may be common denominators in the manifestation of renal toxicity induced by heavy metals. Factors affecting availability and loss of copper should be identified and measured. The critical kidney concentration for Cd, Pb, and MeHg should be revised in relation to essential elements.

Thioacetamide- and carbon tetrachloride-induced liver cirrhosis

Two methods of inducing liver cirrhosis in the rat were studied. Intragastric administration of CCl4 for 16 weeks according to Proctor and Chatamra was compared to the administration of thioacetamide in the drinking water (0.3 g/l) for the same period. CCl4 administration induced micronodular cirrhosis in 6/8 animals with a 27% mortality. Thioacetamide induced cirrhosis in 6/8 animals without mortality. The histologic pictures differed somewhat in that the CCl4 group exhibited more necrosis and cellular swelling while the thioacetamide group had more nuclear atypias and proliferation. Biochemically both groups had elevated plasma levels of aspartate aminotransferase. The lysosomal enzyme beta-hexosaminidase (beta-NAG) showed a transient increase in the thioacetamide animals, while beta-glucuronidase decreased. CCl4-induced cirrhosis led to an increase in beta-NAG. Plasma zinc decreased in both groups as well as liver zinc content in the CCl4 group, while there was a continuous elevation of liver zinc in the thioacetamide group. We conclude that oral administration of thioacetamide is a simple and reliable method of inducing experimental liver cirrhosis. The differences in histological appearances and some biochemical parameters may be caused by the different mechanisms of action of thioacetamide and CCl4.

Trace element alterations in infectious diseases

Trace elements like copper, zinc, iron and selenium have a significant influence on the function of the immune system. We studied plasma levels of trace elements in 53 patients with acute bacterial and viral infections. In bacterial infections (septicaemia, pneumonia, erysipelas and meningitis) the plasma concentrations of selenium, iron and zinc were decreased. Plasma copper was unchanged in patients with erysipelas, but increased in other types of bacterial infections. Although the patients with viral infections showed similar shifts of the trace elements as were observed in patients with bacterial infections, the changes were not as pronounced. A plasma selenium value below 0.8 mumol/l was found in only 6% of the patients with viral infections in contrast to 63% of the patients with septicaemia or 57% of the patients with pneumonia. Furthermore, in viral infections 60% of the zinc values were below the mean level of 12.8 mumol/l observed in healthy controls as compared with 90% of the values in patients with sepsis or 92% of the values in patients with pneumonia. The onset of change in trace elements occurred within a few days and persisted for several weeks. These changes seem to be non-specific and are independent of the agent causing infection. The different types of infections were followed by changes in most of the plasma proteins which are known to be associated with an inflammatory reaction. The changes in plasma proteins were most pronounced in patients with sepsis and pneumonia. Patients with sepsis having a high degree of inflammation did not show a positive correlation between the severity of the disease--as judged by plasma proteins--and the alterations of trace elements.

Antagonistic effect of selenite on tumor promoter induced cell proliferation in cultures of rat tongue epithelium

In cultures of rat tongue epithelial cells, cell proliferation following incubation with different doses of the potent tumor promoter TPA has been studied by using a stathmokinetic method counting colchicine arrested metaphases. It was demonstrated that 24 h incubation with concentrations higher than 5 ng TPA/mL medium caused inhibition, whereas below 5 ng TPA/mL medium caused stimulation of the mitotic activity reaching a maximum around 30 h from the start of the incubation period. Based on the evidence of the anticarcinogenic effect of selenium in several animal models, experiments have been performed elucidating the influence of an atoxic dose (1/1.000.000M) of selenite on the observed TPA-induced cell proliferation. Our results indicate that addition to the culture medium of an atoxic dose of selenite, not affecting the mitotic activity of control cultures, inhibits the TPA-induced stimulation of cell proliferation.

Early biochemical and histological changes in rats exposed to a single injection of thioacetamide

Liver injury was induced by one subcutaneous administration of thioacetamide (200 mg/kg b.wt.) and studied 24 and 48 hrs later. Levels of aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) increased after 24 and 48 hrs. The lysosomal enzymes beta-hexosaminidase (beta-NAG) and beta-glucuronidase (beta-GLU) increased significantly after 24 hrs, while the level of beta-GLU returned to normal after 48 hrs, but the activity of beta-NAG remained significantly high even after 48 hrs. Histopathological examination showed necrotic hepatocytes around the central vein with infiltration of macrophages, neutrophils and eosinophils. The plasma zinc level decreased after 24 hrs and returned to normal after 48 hrs. Liver zinc content increased simultaneously at 24 hrs, returning to normal after 48 hrs. No alterations of plasma copper were observed after 24 and 48 hrs. Copper content of the liver increased significantly after 24 and 48 hrs. The present study thus shows that one dose of thioacetamide results in profound liver injury and supplementation of zinc prior to and simultaneously with thioacetamide normalized plasma zinc, increased liver zinc content and reduced the increase of beta-NAG, but did not influence the histological changes.

Iron, zinc and folate status during pregnancy and two months after delivery

Iron, zinc and folate statuses of 45 women were determined during pregnancy around 12, 20, 28, 32 and 36 weeks, and again 2 months after delivery. Analyses of plasma ferritin, Hb, MCV, folate and zinc in plasma and whole blood were performed. Iron supplementation was recommended from mid-pregnancy but 13 of the participants did not use the iron supplements. This group had significantly decreased levels of plasma ferritin and MCV at the end of pregnancy, but none developed anemia. Two months post partum the plasma ferritin of the unsupplemented group had normalized and was in the same range as in the supplemented group. The concentrations of zinc in plasma and whole blood and the calculated levels of red cells were low even at the first examination around 12 weeks of gestation, compared with non-pregnant women. Throughout the course of pregnancy the plasma zinc levels continued to decrease, while the whole blood and red cell levels showed a significant rise. At term of gestation almost half the women had subnormal plasma folate levels (L. casei), which persisted during the post partum follow-up. The corresponding value for red cell folate was 10% below normal values at term and 30% subnormal 2 months after parturition. These findings stress the importance of extending the observation period to include also the lactating period, in order to judge the need for folate supplementation.

Alterations in trace element and plasma amino-acid profile in experimental gram-negative septicaemia

Infection can produce changes in the levels of trace metals such as copper, iron and zinc and several amino acids. These trace metals are involved in many metabolic reactions as well as in the host defence response. In the present study we have induced septicaemia in male Sprague-Dawley rats. The rats were made septic by surgical insertion of a gelatine capsule containing known amounts of E. coli (1.25 x 10(7) bact/ml) and Bacteroides fragiles (2.5 x 10(7) bact/ml) along with sterile rat faeces as an adjuvant (50% vol/vol), and barium sulphate (10% weight/weight) as an irritant into the abdomen. Blood samples were collected at 36, 60 and 72 h to study alterations in the pattern of copper, zinc, calcium and magnesium and plasma amino acids. Liver samples were taken after sacrifice at 72 h for inorganic element analysis. Sepsis produced a significant increase in copper and magnesium and a significant decrease in zinc and calcium levels of plasma. Trace element content of the livers the septic rats did not differ appreciably from control rats. Septic rats also had a lowered concentration of branched chain amino acids. These changes especially those of copper and zinc could be expected to have a role in the progress of the disease. The changes observed in the present study might be caused through the release of Interleukin-I or related substances from the phagocytic cells.

Nutrient intake and health status of lactovegetarians: chemical analyses of diets using the duplicate portion sampling technique

Six middle-aged lactovegetarians (three men and three women) collected copies of four 24-h diets using the duplicate portion sampling technique. By chemical analyses, the nutrient composition of the lactovegetarian diet was determined in detail and compared with that of a mixed Swedish diet (normal) and a vegan diet (vegan) studied previously. The nutrient composition of the lactovegetarian diet expressed per 1000 kcal represented an average between normal and vegan diets. It was in closer agreement with Swedish recommended dietary allowances than the normal Swedish diet. Thus, the lactovegetarian diet contained 35% of the energy as fat and was rich in polyunsaturated fatty acids, especially linoleic acid, which resulted in a polyunsaturated/saturated fat ratio of 0.6. The lactovegetarian diet had a cholesterol concentration only half of that of a normal diet. Protein content and amino acid composition were well above recommendations. The lactovegetarian diets contained less sucrose than normal and vegan diets, but the sum of the intake of low molecular weight carbohydrates was comparable to normal and vegan diets. Dietary fiber was three times higher than in a normal diet. Essential minerals and trace elements, ie, Ca, Mg, Na, K, Fe, Zn, Cu, Se, satisfied current requirements. The intake of vitamin B12 by the lactovegetarians was around 1.4 micrograms daily, which is below the recommendations. The intake of folates was high, 300 to 400 micrograms daily. The clinical and biochemical investigation of the subjects revealed no signs of nutritional deficiency. Their plasma lipoproteins and the blood pressures were low for their age, in agreement with observations made earlier in a group of vegans.

Zinc, copper, magnesium, and calcium in blood and plasma after phlebotomy

Zinc levels in plasma and whole blood were investigated in 2 groups of blood donors. The first group consisted of 19 men and 11 women who donated blood for the first time and were followed during 3 phlebotomies. The second group comprised 44 men with 9 or more previous blood donations, their blood being analysed on a single occasion. Plasma concentrations of copper, magnesium, calcium and ferritin were also analysed. The zinc levels in whole blood and plasma in the second group were significantly lower as compared to the first group (P less than 0.001). Furthermore, the second group had significantly higher levels of copper and copper:zinc quotient in plasma as compared to those of the new blood donors (P less than 0.001). Our results indicate that besides the earlier known effect of blood donation on iron stores, there are also signs of zinc depletion when judged from the zinc levels in plasma and in erythrocytes. No significant changes in calcium and magnesium concentrations were seen during phlebotomy.

Public health/clinical significance of inorganic chemical elements

Food tables documenting the concentration of various nutrients in individual foods do not provide satisfactory information on the contribution of essential inorganic trace elements by prepared meals. Only direct analysis of the actual food consumed during a 24-hour period can give an accurate estimate of the dietary intake. Employing the duplicate portion technique, we have analysed the concentration of a number of inorganic chemical elements in 882 dietary samples from various population groups in Sweden. The intake of several elements including potassium, magnesium, zinc, copper and selenium, in the normal mixed diets is low when compared with recommended dietary allowances (RDA). Vegetarian diets are richer in these elements than ordinary non-vegetarian diets. Plasma levels of trace elements are often poor indicators of body status. A clinical follow-up of a group of pensioners in Dalby, Sweden, for a period of 10-12 years has not indicated any specific signs or symptoms of trace element deficiencies. Vulnerable groups, namely, children, pregnant women, alcoholics and the elderly, may, however, be more susceptible than the population in general to marginal deficiencies resulting from normal everyday consumption of Western diets.

Nutrient intake and health status of vegans. Chemical analyses of diets using the duplicate portion sampling technique

A strict vegetarian diet [vegan diet (VD)] was investigated. Six middle-aged vegans (three men and three women) collected copies of 24-h diets using the duplicate portion sampling technique. By chemical analyses, the nutrient composition was determined in detail and compared with corresponding figures of a normal mixed Swedish diet. In the VD 30% of the energy originated from fat compared with 40% in normal Swedish mixed diet (MD). Linoleic acid was the dominant fatty acid (60% of total fat in VD versus 8% in MD). The VD contained 24 g protein/1000 kcal compared to 30 g/1000 kcal in MD, but the intake of essential amino acids by the vegans exceeded the recommendations. Dietary fiber was about 5 times higher in the vegan diet (29 versus 6 g/1000 kcal) and sucrose similar to MD (18 versus 21 g/1000 kcal). Among the inorganic nutrients the concentration of calcium (351 versus 391 mg/1000 kcal) and sodium (53 versus 49 mmol/1000 kcal) were similar in both types of diets but the amount of potassium (56 versus 30 mmol/1000 kcal, magnesium (300 versus 110 mg/1000 kcal), iron (9 versus 6.5 mg/1000 kcal), zinc (6.5 versus 4.7 mg/1000 kcal), and copper (2 versus 0.7 mg/1000 kcal) were nearly doubled. Iodine (39 versus 156 micrograms/1000 kcal and selenium (5 versus 17 micrograms/1000 kcal) were much lower in the VD, selenium even being undetectable in several 24-h diets. The VD was rich in folic acid (301 versus 90 micrograms/1000 kcal in MD) but the intake of vitamin B12 was only 0.3 to 0.4 microgram/day (MD: 3 to 4 micrograms/day). No clinical signs of nutritional deficiency were observed in the vegans. Serum protein levels of the vegans as well as their serum lipoproteins were near the lower range of the reference group. In addition, none of the vegans was overweight and their blood pressures were low for their age.

Antagonistic effects of zinc and aluminum on lead inhibition of delta-aminolevulinic acid dehydratase

In vitro and in vivo studies regarding the influence of metals on delta-aminolevulinic acid dehydratase activity in erythrocytes indicate that a lead concentration of 4 micrometer/l completely inhibits the enzyme. Zinc activates the enzyme both in vitro and in vivo at concentrations greater than 76 micrometer/l. Aluminum has an inhibitory effect at all concentrations in vitro whereas it activates the enzyme in vivo. Zinc and aluminum together activate the enzyme in vivo. The in vitro activation of zinc is inhibited by increasing concentrations of aluminum. Aluminum and lead together depress the enzyme activity in an additive way that can be reactivated by the addition of zinc.

Effect of different levels of dietary zinc on development of chemically induced oral cancer in rats

Four-week-old female rats distributed among three experimental groups were fed a 0.23 (zinc-deficient), 0.77 (zinc-adequate) or 3.06 (zinc-supplemented) mmol zinc/kg diet and oral cancer was induced by repeated application of the water-soluble carcinogen 4-nitroquinoline N-oxide (4NQO) to the palatal mucosa. The clinical development of oral cancer differed significantly among the three groups (P less than 0.05). In rats fed the zinc-supplemented diet, the macroscopic oral cancer appeared early and the survival time was shorter than in either of the other groups. It was concluded that a zinc-supplemented diet accelerates, and a zinc-deficient diet retards the development of chemically induced oral cancer in rats.

Effect of oral zinc intake on delta-aminolaevulinic acid dehydratase in red blood cells

Earlier results regarding the in vitro and in vivo effects of zinc on delta-aminolaevulinic acid dehydratase (ALAD) activity in red blood cells were confirmed in healthy human subjects after oral intake of zinc for 12 weeks. In one group of seven healthy adults, oral intake of zinc for 12 weeks. In one group of seven healthy adults, oral intake of zinc, as the sulphate salt (2.07 mmol zinc/day) for 6 weeks, resulted in a 44% increase in the activity of ALAD in erythrocytes. Plasma zinc levels also increased during the experimental period and reached a maximum of 29 mumol after 6 weeks and remained constant thereafter. In another group, the intake of zinc in a lower dose, (0.69 mmol zinc/day) for 12 weeks, showed a similar tendency, although the increase in the enzyme activity, as well as the plasma zinc levels, was relatively much less. The plasma copper levels decreased significantly in the second group after the zinc intake and reached a low value of 11 mumol at the end of the experimental period. The Cu:Zn ratio also decreased considerably towore valuable indicator of zinc status than plasma zinc levels alone.

Zinc and copper levels in whole blood and plasma from patients with squamous cell carcinomas of head and neck

Zinc in plasma and whole blood from 13 patients with squamous cell carcinoma of the head and neck was significantly decreased, and the copper:zinc ratio in the plasma was significantly higher than in healthy controls. The plasma zinc was significantly lower in patients who did not respond to therapy and who died within 12 months than in those who responded to therapy and had a remission within 12--15 months. In patients responding to therapy and alive after 12--15 months, zinc in the plasma and whole blood and the copper:zinc ratio became normal. These results suggest a potential screening and predicting value of zinc in the plasma and whole blood and the copper:zinc ratio in squamous cell carcinoma of the head and neck.

Oral carotenoids for photohypersensitivity in patients with erythrohepatic protoporphyria, polymorphous light eruptions and lupus erythematodes discoides

beta-Carotene and canthaxanthin in a dose of 75--250 mg a day by mouth reduced the symptons of exposure to the sun in all 7 treated patients with erythrohepatic protoporphyria (EPP), in 15 of 18 with polymorphous light eruptions (PMLE) and in 3 of 4 with lupus erythematodes discoides. In the EPP group the protoporphyrin level tended to vary inversely with that of the serum carotenoids. The level of retinol-binding protein in plasma remained unchanged despite a substantial rise in the concentration of the serum carotenoids. Estimation of the minimal erythema dose for unfiltered light from a Xenon lamp in 7 patients with PMLE showed an increase in only 1 patient. Neither clinical examination nor repeated laboratory studies revealed any serious side effects of the treatment.

Influence of zinc on onset and progression of oral carcinogenesis in rats

Three-week-old female rats were fed 0.09 (zinc-deficient), 0.77 (zinc-adequate) or 3.98 (zinc-supplemented) mmol zinc/kg diet in three experimental groups and the palatal mucosa was painted with the water-soluble carcinogen 4-nitroquinoline N-oxide (4NQO) three times a week for 20 weeks. The zinc-supplemented diet seemed to retard the induction of carcinogenesis, whereas a low-zinc diet had the opposite effect. Once initial cellular changes had been induced the supplementary zinc seemed to accelerate their further advancement. Zinc-deficiency in animals fed a copper/zinc low-zinc diet was reflected in the plasma and liver zinc levels as well as in the copper/zinc ratio. The development of cancer was accompanied by a decrease in plasma zinc and an increase in the plasma copper/zinc ratio as well as in the liver zinc. These changes were most remarkable in the zinc-supplemented group.

Zinc and copper concentrations in serum, blood and liver in moderate experimental pancreatic insufficiency

Serum and liver concentrations of zinc and copper were studied in the rat after ligation of the pancreatic duct. Ligation of the bile duct was done close to the duodenum and high up in the hilum of the liver. The bile flow was by-passed into the intestine via a plastic catheter. The surgical method used was found suitable for a study of moderate exocrine pancreatic insufficiency since significant--although markedly reduced--concentrations of amylase and trypsin were estimated in intestinal contents at sacrifice 19 weeks after the operation. The serum zinc level was unaffected by duct ligation except for a slight decrease after 2 weeks. Similarly zinc in whole blood was unaffected. The copper concentration in serum was, however, significantly enhanced during in first 10 weeks. The copper zinc ration was markedly increased in duct ligated rats during the whole period. Zinc and copper concentrations in liver tissue were significantly decreased after 19 weeks. The findings suggest that a decrease function of exocrine pancreas might induce a disturbed balance of zinc and copper in the rat.