An environmentally sensitive zinc-selective two-photon NIR fluorescent turn-on probe and zinc sensing in stroke

A two-photon near infrared (NIR) fluorescence turn-on sensor with high selectivity and sensitivity for Zn2+ detection has been developed. This sensor exhibits a large Stokes' shift (∼300 nm) and can be excited from 900 to 1000 nm, with an emission wavelength of ∼785 nm, making it ideal for imaging in biological tissues. The sensor's high selectivity for Zn2+ over other structurally similar cations, such as Cd2+, makes it a promising tool for monitoring zinc ion levels in biological systems. Given the high concentration of zinc in thrombi, this sensor could provide a useful tool for in vivo thrombus imaging.

Zinc regulates reactive oxygen species generation in platelets

Vascular complications resulting from atherosclerosis development are a major cause of death. Reactive oxygen species (ROS) are produced by platelets during activation, and have been demonstrated to positively regulate platelet activatory responses. Zn2+ is also an important hemostatic cofactor in platelets, acting both as a platelet agonist and second messenger. Whilst the effect of Zn2+-dependent signaling mechanisms on ROS production in nucleated cells has been demonstrated, comparable roles in platelets have yet to be investigated. In this study we investigated the relationship between fluctuations in cytosolic Zn2 [Zn2+]i and platelet ROS production. Agonist-evoked ROS production, GSH levels and GPx activity are abrogated in platelets treated with the Zn2+-chelator, TPEN. Conversely, increasing platelet [Zn2+]i using Zn2+ ionophores potentiated ROS generation and decreased GSH levels and GPx activity. Zn2+-dependent ROS production was sensitive to pretreatment with DPI or mitoTEMPO, NADPH oxidase and mitochondria inhibitors respectively. Increasing [Zn2+]i resulted in increases of Erk1/2 and JNK phosphorylation. Our data are consistent with a functional association between [Zn2+]i and ROS production in platelets that could influence thrombus formation in a clinical context.

The contribution of zinc to platelet behaviour during haemostasis and thrombosis

Platelets are the primary cellular determinants of haemostasis and pathological thrombus formation leading to myocardial infarction and stroke. Following vascular injury or atherosclerotic plaque rupture, platelets are recruited to sites of damage and undergo activation induced by a variety of soluble and/or insoluble agonists. Platelet activation is a multi-step process culminating in the formation of thrombi, which contribute to the haemostatic process. Zinc (Zn(2+)) is acknowledged as an important signalling molecule in a diverse range of cellular systems, however there is limited understanding of the influence of Zn(2+) on platelet behaviour during thrombus formation. This review evaluates the contributions of exogenous and intracellular Zn(2+) to platelet function and assesses the potential pathophysiological implications of Zn(2+) signalling. We also provide a speculative assessment of the mechanisms by which platelets could respond to changes in extracellular and intracellular Zn(2+) concentration.

Zinc is a transmembrane agonist that induces platelet activation in a tyrosine phosphorylation-dependent manner

Following platelet adhesion and primary activation at sites of vascular injury, secondary platelet activation is induced by soluble platelet agonists, such as ADP, ATP, thrombin and thromboxane. Zinc ions are also released from platelets and damaged cells and have been shown to act as a platelet agonist. However, the mechanism of zinc-induced platelet activation is not well understood. Here we show that exogenous zinc gains access to the platelet cytosol and induces full platelet aggregation that is dependent on platelet protein tyrosine phosphorylation, PKC and integrin αIIbβ3 activity and is mediated by granule release and secondary signalling. ZnSO4 increased the binding affinity of GpVI, but not integrin α2β1. Low concentrations of ZnSO4 potentiated platelet aggregation by collagen-related peptide (CRP-XL), thrombin and adrenaline. Chelation of intracellular zinc reduced platelet aggregation induced by a number of different agonists, inhibited zinc-induced tyrosine phosphorylation and inhibited platelet activation in whole blood under physiologically relevant flow conditions. Our data are consistent with a transmembrane signalling role for zinc in platelet activation during thrombus formation.

Influence of DNA-methylation on zinc homeostasis in myeloid cells: Regulation of zinc transporters and zinc binding proteins

The distribution of intracellular zinc, predominantly regulated through zinc transporters and zinc binding proteins, is required to support an efficient immune response. Epigenetic mechanisms such as DNA methylation are involved in the expression of these genes. In demethylation experiments using 5-Aza-2'-deoxycytidine (AZA) increased intracellular (after 24 and 48h) and total cellular zinc levels (after 48h) were observed in the myeloid cell line HL-60. To uncover the mechanisms that cause the disturbed zinc homeostasis after DNA demethylation, the expression of human zinc transporters and zinc binding proteins were investigated. Real time PCR analyses of 14 ZIP (solute-linked carrier (SLC) SLC39A; Zrt/IRT-like protein), and 9 ZnT (SLC30A) zinc transporters revealed significantly enhanced mRNA expression of the zinc importer ZIP1 after AZA treatment. Because ZIP1 protein was also enhanced after AZA treatment, ZIP1 up-regulation might be the mediator of enhanced intracellular zinc levels. The mRNA expression of ZIP14 was decreased, whereas zinc exporter ZnT3 mRNA was also significantly increased; which might be a cellular reaction to compensate elevated zinc levels. An enhanced but not significant chromatin accessibility of ZIP1 promoter region I was detected by chromatin accessibility by real-time PCR (CHART) assays after demethylation. Additionally, DNA demethylation resulted in increased mRNA accumulation of zinc binding proteins metallothionein (MT) and S100A8/S100A9 after 48h. MT mRNA was significantly enhanced after 24h of AZA treatment also suggesting a reaction of the cell to restore zinc homeostasis. These data indicate that DNA methylation is an important epigenetic mechanism affecting zinc binding proteins and transporters, and, therefore, regulating zinc homeostasis in myeloid cells.

Impact of Ficoll density gradient centrifugation on major and trace element concentrations in erythrocytes and blood plasma

PROJECT

Ficoll density gradient centrifugation is widely used to separate cellular components of human blood. We evaluated the suitability to use erythrocytes and blood plasma obtained from Ficoll centrifugation for assessment of elemental concentrations.

PROCEDURE

We determined 22 elements (from Li to U) in erythrocytes and blood plasma separated by direct or Ficoll density gradient centrifugation, using inductively coupled plasma mass spectrometry.

RESULTS

Compared with erythrocytes and blood plasma separated by direct centrifugation, those separated by Ficoll had highly elevated iodine and Ba concentration, due to the contamination from the Ficoll-Paque medium, and about twice as high concentrations of Sr and Mo in erythrocytes. On the other hand, the concentrations of Ca in erythrocytes and plasma were markedly reduced by the Ficoll separation, to some extent also Li, Co, Cu, and U. The reduced concentrations were probably due to EDTA, a chelator present in the Ficoll medium. Arsenic concentrations seemed to be lowered by Ficoll, probably in a species-specific manner. The concentrations of Mg, P, S, K, Fe, Zn, Se, Rb, and Cs were not affected in the erythrocytes, but decreased in plasma. Concentrations of Mn, Cd, and Pb were not affected in erythrocytes, but in plasma affected by EDTA and/or pre-analytical contamination.

CONCLUSIONS

Ficoll separation changed the concentrations of Li, Ca, Co, Cu, As, Mo, I, Ba, and U in erythrocytes and blood plasma, Sr in erythrocytes, and Mg, P, S, K, Fe, Zn, Se, Rb and Cs in blood plasma, to an extent that will invalidate evaluation of deficiencies or excess intakes.

Stenotrophomonas maltophilia virulence and specific variations in trace elements during acute lung infection: implications in cystic fibrosis

Metal ions are necessary for the proper functioning of the immune system, and, therefore, they might have a significant influence on the interaction between bacteria and host. Ionic dyshomeostasis has been recently observed also in cystic fibrosis (CF) patients, whose respiratory tract is frequently colonized by Stenotrophomonas maltophilia. For the first time, here we used an inductively mass spectrometry method to perform a spatial and temporal analysis of the pattern of changes in a broad range of major trace elements in response to pulmonary infection by S. maltophilia. To this, DBA/2 mouse lungs were comparatively infected by a CF strain and by an environmental one. Our results showed that pulmonary ionomic profile was significantly affected during infection. Infected mice showed increased lung levels of Mg, P, S, K, Zn, Se, and Rb. To the contrary, Mn, Fe, Co, and Cu levels resulted significantly decreased. Changes of element concentrations were correlated with pulmonary bacterial load and markers of inflammation, and occurred mostly on day 3 post-exposure, when severity of infection culminated. Interestingly, CF strain – significantly more virulent than the environmental one in our murine model - provoked a more significant impact in perturbing pulmonary metal homeostasis. Particularly, exposure to CF strain exclusively increased P and K levels, while decreased Fe and Mn ones. Overall, our data clearly indicate that S. maltophilia modulates pulmonary metal balance in a concerted and virulence-dependent manner highlighting the potential role of the element dyshomeostasis during the progression of S. maltophilia infection, probably exacerbating the harmful effects of the loss of CF transmembrane conductance regulator function. Further investigations are required to understand the biological significance of these alterations and to confirm they are specifically caused by S. maltophilia.

Sputum trace metals are biomarkers of inflammatory and suppurative lung disease

BACKGROUND

Induced sputum cytology and protein biomarkers can be used to assess airways inflammation. Increases in sputum iron have been described in inflammatory lung disease. We hypothesized that other sputum metals may be affected by airways inflammation and investigated their potential value as biomarkers.

METHODS

Sputum was obtained from 20 healthy control subjects and from patients with inflammatory pulmonary diseases (23 with cystic fibrosis [CF], 16 with bronchiectasis, 17 with asthma, and 23 with COPD), and iron, zinc, manganese, and copper were measured. Fourteen patients with CF were also studied through an exacerbation cycle.

RESULTS

Sputum zinc and iron were elevated in CF and non-CF bronchiectasis vs controls (P < .001, zinc; P < .01 iron). Manganese was elevated in asthma (P < .01) and bronchiectasis (P < .05) vs controls. Copper was elevated in CF vs controls (P < .05). Zinc decreased (P < .01) following treatment of CF exacerbation. In subjects with CF zinc levels correlated with other biomarkers.

CONCLUSIONS

These results suggest a relationship of high concentrations of total zinc and iron with airways inflammation in CF and non-CF bronchiectasis, with longitudinal changes being observed in CF. Further work is required to elucidate potential inflammatory mechanisms related to these observations.

Zinc transporters ZnT1 (Slc30a1), Zip8 (Slc39a8), and Zip10 (Slc39a10) in mouse red blood cells are differentially regulated during erythroid development and by dietary zinc deficiency

Zinc is essential for normal erythroid cell functions and therefore intracellular zinc homeostasis during erythroid differentiation is tightly regulated. However, a characterization of zinc transporters in erythrocytes has not been conducted. The membrane fraction of mature mouse RBC was screened for zinc transporter expression using western analysis as a first step in the characterization process. ZnT1, Zip8, and Zip10 were detected among the 12 transporter proteins tested. We examined expression of these zinc transporters during erythropoietin (EPO)-induced differentiation of splenic erythroid progenitor cells into reticulocytes. Both Zip8 and Zip10 mRNA increased by 2-6 h after addition of EPO to the cells. In contrast, maximal RNA levels for the zinc transporter ZnT1 and erythroid delta-aminolevulinic acid synthase were only produced by 24 h after EPO. We confirmed these changes in transcript abundance by western analysis. Dietary zinc status influences zinc-dependent functions of RBC. To determine whether the identified zinc transporters respond to dietary zinc status, mice were fed a zinc-deficient or control diet. Incorporation of (65)Zn into erythrocytes in vitro was significantly increased in cells from the zinc-deficient mice. Western analysis and densitometry revealed that erythrocyte Zip10 was upregulated and ZnT1 was downregulated in the zinc-depleted mice. Zip8 was not affected by restricted zinc intake. Collectively, these data suggest that the zinc transporters ZnT1, Zip8, and Zip10 are important for zinc homeostasis in erythrocytes and that ZnT1 and Zip10 respond to the dietary zinc supply.

Relation between pyridoxal and pyridoxal phosphate concentrations in plasma, red cells, and white cells in patients with critical illness

BACKGROUND

Evidence suggests that the relation between plasma and red cell vitamin B-6 concentrations is perturbed as part of the systemic inflammatory response in critically ill patients.

OBJECTIVE

The aim was to examine the cross-sectional and longitudinal interrelations between pyridoxal (PL) and pyridoxal phosphate (PLP) concentrations in plasma and red and white cells in patients with critical illness.

DESIGN

PLP and PL concentrations were measured by HPLC in plasma and red and white cells in normal subjects (n = 126) and critically ill patients (n = 96) on admission and on follow-up.

RESULTS

On admission, compared with the controls, median plasma PLP and PL (P < 0.001 and < 0.01, respectively) and red cell PLP and PL (P < 0.001 and < 0.05, respectively) and their ratio (PLP:PL) in plasma and red cells (P < 0.001 and < 0.01, respectively) were significantly lower in the critically ill. In critically ill patients, plasma PLP:PL was significantly lower than red cell PLP:PL (P = 0.001) and white cell PLP:PL (P = 0.008). Plasma PL concentration was directly associated with both red cell PL (r(s) = 0.73, P < 0.001) and white cell PL (r(s) = 0.68, P < 0.001). Red cell PL and white cell PL were directly associated with red cell PLP (r(s) = 0.82, P < 0.001) and white cell PLP (r(s) = 0.68, P < 0.001), respectively. Longitudinal measurements (n = 48) were similar.

CONCLUSIONS

The relation between plasma PLP and PL was significantly perturbed in critical illness. This effect was less pronounced in red and white cells. Therefore, these results confirm the hypothesis that intracellular PLP concentrations are more likely to be a reliable measure of status than are plasma measurements in the critically ill patient.

Some magnesium status indicators and oxidative metabolism responses to low-dietary magnesium are affected by dietary copper in postmenopausal women

OBJECTIVE

A study with human volunteers was conducted to ascertain whether a low intake of copper (Cu) would exacerbate the response to a deficient intake of magnesium (Mg).

METHODS

Nineteen postmenopausal women, age 47 to 78 y, completed a metabolic unit study as designed. For 162 d, nine women were fed a diet containing 1.0 mg of Cu/2000 kcal and 10 women were fed 3.0 mg of Cu/2000 kcal. Diets contained 99 or 399 mg of Mg/2000 kcal for 81 d in a randomized, double-blind, crossover design. Differences were considered significant when statistical analysis yielded P </= 0.05.

RESULTS

Magnesium balance was highly positive when the dietary magnesium was high but non-positive when dietary magnesium was low. Copper balance was more positive when dietary copper was high than when it was low. Plasma ionized magnesium was decreased by magnesium deprivation. Several variables measured indicated that low dietary copper affected the response to magnesium deprivation or vice-versa. Red blood cell magnesium was lower when dietary copper was low than when it was high. When dietary magnesium was low, serum copper was lower in the women fed marginal copper than in those fed luxuriant copper. When dietary magnesium was high, low dietary copper did not affect serum copper. Magnesium deprivation decreased red blood cell superoxide dismutase when dietary copper was luxuriant; when dietary copper was low, magnesium deprivation did not have much of an effect. Apolipoprotein A1 was lowest when dietary magnesium and copper were low. The order in which the magnesium restriction occurred affected the response of a number of variables to this treatment including concentrations of serum magnesium and total and low-density lipoprotein cholesterol.

CONCLUSIONS

The findings indicated that, in short-term magnesium depletion experiments, the response to depletion can be influenced by other dietary factors including copper intake and a high magnesium intake before depletion, and that 100 mg of Mg/d is inadequate for postmenopausal women.

Biomarkers of trace mineral intake and status

The emerging public health importance of zinc and selenium and the continuing public health challenges of iron and iodine draw attention to the unmet need for improved biomarkers of trace element status. Currently available biomarkers of these four trace elements are critiqued including the outstanding lack of satisfactory biomarkers for the assessment of zinc intake and status. Other trace elements are reviewed briefly including copper, for which human dietary deficiencies and excesses have been documented, and chromium, which is of possible but unconfirmed public health significance. Evolving strategies of considerable potential include molecular techniques such as the measurement of metallothionein mRNA in lymphocytes as a biomarker of zinc status, an assay that can now be performed with a dried blood spot. The judicious application of tracer techniques also has a role in advancing the quality of zinc biomarkers. Also of special current interest is full definition of the potential of plasma-soluble transferrin receptor concentrations as the biomarker of choice for the detection of early functional iron deficiency.

Low dietary copper increases fecal free radical production, fecal water alkaline phosphatase activity and cytotoxicity in healthy men

One possible dietary factor that may increase susceptibility to colon cancer is inadequate copper intake. The objective of this study was to investigate the effects of low and adequate copper intakes on copper nutriture and putative risk factors for colon cancer susceptibility in healthy men. Seventeen healthy free-living nonsmoking men aged 21-52 y completed a 13-wk controlled feeding study in a randomized crossover design. The basal diet contained 0.59 mg Cu/13.65 MJ. After a 1-wk equilibration period in which the men consumed the basal diet supplemented with 1.0 mg Cu/d, they were randomly assigned to receive either the basal diet or the basal diet supplemented with 2 mg Cu/d for 6 wk. After the first dietary period, the men immediately began to consume the other level of Cu for the last 6 wk. They collected their feces during the equilibration period and during the last 2 wk of the two dietary periods for free radical and fecal water analysis. Low dietary copper significantly (P < 0.01) increased fecal free radical production and fecal water alkaline phosphatase activity. Low dietary copper significantly (P < 0.0001) decreased fecal water copper concentrations but did not affect fecal water volume, pH, iron or zinc concentrations. In contrast to the fecal analysis, hematological indicators of copper status were not significantly affected by the dietary treatments. These results suggest that low dietary copper adversely affects fecal free radical production and fecal water alkaline phosphatase activity, which are putative risk factors for colon cancer.

Low dietary zinc alters indices of copper function and status in postmenopausal women

OBJECTIVES

To better define the relationship between dietary zinc and copper for humans so that sound recommendations for intakes of these elements can be made.

METHODS

A study was conducted to ascertain the effect of moderately excessive and deficient intakes of zinc on copper metabolism and use in humans fed low and luxuriant amounts of copper. Twenty-one postmenopausal women housed in a metabolic unit completed the study as designed. After a 10-d equilibration period in which they were fed a diet providing 31.5 micromol (2 mg) Cu and 91.8 micromol (9 mg) Zn/8.4 MJ (2000 kcal), the women were divided into two groups. One group was fed a diet containing 15.7 micromol (1 mg) Cu/8.4 MJ (2000 kcal), and the other group was fed a diet containing 47.2 micromol (3 mg) Cu/8.4 MJ (2000 kcal). After equilibration, both groups were fed the basal diet providing 45.9 micromol (3 mg) Zn/8.4 MJ (2000 kcal) for 90 d; this was followed by another 10-d equilibration period before dietary zinc was increased to 811 micromol (53 mg)/8.4 MJ (2000 kcal) for 90 d.

RESULTS

The women were in positive copper balance only when the diet provided 47.2 micromol (3 mg) Cu and 811 micromol (53 mg) Zn/d. Immunoreactive ceruloplasmin concentrations and platelet cytochrome-c oxidase activity on a platelet number basis were significantly lower and the ratio between enzymatic and immunoreactive ceruloplasmin was significantly higher during low dietary than during high dietary zinc intake. Serum cholesterol was higher in subjects fed 15.7 micromol (1 mg) Cu/d than in those fed 47.2 micromol (3 mg) Cu/d. Total and low-density lipoprotein cholesterol concentrations decreased with zinc supplementation. Whole-blood glutathione concentration and erythrocyte glutathione peroxidase activity were lower during high than during low dietary zinc intake.

CONCLUSIONS

The findings indicate that an inadequate intake of zinc (45.9 micromol/d; 3 mg/d) was more effective than a moderately high intake of zinc (811 micromol/d; 53 mg/d) in inducing changes associated with a decreased copper status in postmenopausal women. Furthermore, the findings indicate that copper status indicators might be useful in evaluating changes in zinc status in humans, and an intake of 15.7 micromol (1 mg)/d of copper may be inadequate for postmenopausal women.

Changes in dietary zinc and copper affect zinc-status indicators of postmenopausal women, notably, extracellular superoxide dismutase and amyloid precursor proteins

BACKGROUND

Zinc is an essential trace element for human health and well-being; however, methods currently available for the assessment of zinc status in humans are unsatisfactory.

OBJECTIVE

The objective was to critically evaluate the use of various indicators of zinc status in humans in a controlled metabolic ward study.

DESIGN

Indicators of zinc status were measured in 25 healthy postmenopausal women aged 64.9 +/- 6.7 y. After a 10-d equilibration period, volunteers consumed a diet with either a low (1 mg/d; n = 12) or a high (3 mg/d; n = 13) copper content based on a total energy content of 8.4 MJ. They received the same amount of copper throughout the study. Both groups were fed the basal diet (3 mg Zn/d) with no zinc supplement for one 90-d period, and the diet supplemented with 50 mg Zn/d for another 90-d period.

RESULTS

Zinc supplementation significantly increased (P < 0.0001) extracellular but not erythrocyte superoxide dismutase activity. This increase was more apparent when subjects were fed the low-copper diet. Zinc supplementation in combination with the low-copper diet significantly decreased (P < 0.01) amyloid precursor protein expression in platelets. Other indicators of zinc status that were significantly elevated after zinc supplementation were as follows: plasma zinc and free thyroxine concentrations and mononuclear 5'-nucleotidase activity.

CONCLUSION

The measurement of serum extracellular superoxide dismutase activity may be useful as a marker for the functional assessment of zinc status in humans.

Are copper, zinc and selenium in erythrocytes valuable biological indexes of nutrition and pathology?

The real significance of the level of trace elements copper, zinc and selenium in erythrocytes is still a matter of debate. This review is an evaluation of the potential value of copper, zinc and selenium in red blood cells in physiology, nutrition and pathology, taking into account the other commonly used indices and the analytical difficulty encountered for erythrocyte determinations. The main analytical methods and reference values in erythrocytes are also presented. The literature of the last 3 decades was analyzed. On the basis of these papers, the role of erythrocyte copper in various pathologies should be re-investigated, especially when they include inflammatory processes or hormonal changes. The main interest of zinc determination in red blood cells concerns thyroid pathology. In general, the value of selenium in erythrocytes agrees with selenium in serum and its determination is often unnecessary.

[Diagnosis of zinc deficiency]

Though far more common, particularly in elderly people, than was previously assumed, marginal zinc deficiency does not lead to the classical manifestations of zinc deficiency and is therefore difficult to diagnose. There is therefore a need for sensitive parameters that can reliably demonstrate even marginal zinc deficiency, as suboptimal zinc status can seriously impair human health, performance, reproductive functions, and mental and physical development. The most important criteria for the diagnosis of zinc deficiency are critically discussed. The laboratory parameters currently considered to be the most useful indicators of marginal zinc deficiency are zinc-binding capacity and serum/plasma alkaline phosphatase activity before and after zinc supplementation (zinc tolerance test!). In order to obtain a reliable assessment of a patients zinc status, a number of different diagnostic parameters should always be measured.

Zinc status in patients with alveolar echinococcosis is related to disease progression

Zinc is an essential trace element for immune function that plays a role in immune response against parasites. To determine a possible relationship between zinc level and disease status in alveolar echinococcosis (AE), we investigated serum concentrations of zinc, immunoglobulin (Ig)E, IgG, and C-reactive protein (CRP) in 40 AE patients and 20 controls. Patients were classified into three groups: group A: patients after curative surgery, group B: patients with stabilized disease, group C: patients with progressive disease. Patients showed significantly higher levels of IgE and IgG than controls. Amounts of IgE and IgG were related to disease severity, achieving highest levels in group C and lowest in group A. Zinc levels were comparable in patients and controls. However, there was an obvious association between zinc concentration and disease severity. Zinc was far below the normal range in group C (median 9.2 micromol/l) and significantly diminished compared to group B and controls. An inverse pattern was seen for CRP. In conclusion, lowered zinc concentration in progressive cases may be caused by enhanced immune activation but consumption of zinc by the growing parasite may also play a role. Furthermore, decreased zinc levels may contribute to the observed immunosuppression in AE.

The value of methods to determine zinc deficiency in patients with Crohn's disease

BACKGROUND

The serum zinc concentration is frequently applied for the assessment of zinc deficiency, but this concentration is also influenced by other factors. The aim of this study was to compare various methods of assessing the zinc status in patients with Crohn' s disease.

METHODS

Serum levels of zinc, serum alkaline phosphatase activity, and zinc in various types of cells were related to factors potentially inducing zinc deficiency: the number of liquid stools, weight loss, bowel resection, and the extent and severity of inflammation.

RESULTS

Thirty-one patients with more or less active Crohn's disease were included. In 68% of these patients the serum zinc concentration was less than the reference level, and it was correlated with the extent of bowel resection and the van Hees Index but not with the Crohn's Disease Activity Index. Serum alkaline phosphatase activity was correlated with bowel resection. Zinc in blood cells was poorly correlated with factors inducing zinc deficiency.

CONCLUSION

A decrease of serum zinc concentration is frequently seen in active Crohn's disease. This study suggests that the determination of zinc in blood cells is not superior to the determination of the serum zinc concentration and serum alkaline phosphatase activity.

A bereavement support group intervention is longitudinally associated with salutary effects on the CD4 cell count and number of physician visits

A randomized, controlled, clinical trial was conducted to examine the impact of a semistructured, 10-week, once weekly, 90-min/session bereavement support group intervention on immunological, neuroendocrine, and clinical health status in human immunodeficiency virus type 1-seropositive (HIV-1+) and HIV-1-seronegative (HIV-1-) homosexual men, compared to a standard of care control condition. A total of 119 homosexual men (74 HIV-1+ and 45 HIV-1-) were assessed at baseline, 10 weeks, and 6 months follow-up. At the 6-month follow-up assessment, the intervention groups exhibited significant beneficial effects compared to controls on changes in CD4 cell, total T-lymphocyte, and total lymphocyte counts, when baseline levels, antiretroviral medication use, CDC stage of disease, and other potentially confounding factors were accounted for. There was no statistically significant effect on the CD4/CD8 ratio or on the CD8 cell count. The effect on CD4 cell count was associated with group attendance and with changes in plasma cortisol level. Plasma cortisol levels decreased significantly among intervention subjects, compared to controls. A significantly reduced number of health care visits over the 6-month follow-up period among the intervention subjects supported the clinical relevance of the immunological changes observed for both HIV-1+ and HIV-1- individuals. These results indicate that behavioral interventions may have salutary immunological and clinical health effects following bereavement among HIV-1-infected individuals. The effect in HIV-1- individuals suggests that this bereavement support group intervention might have similar salutary effects in the general population. Potential effects of such interventions on clinical HIV disease progression are of interest and should be studied.

Effects of captopril and enalapril on zinc metabolism in hypertensive patients

OBJECTIVE

To investigate the effect of chronic captopril and enalapril treatment on zinc metabolism in hypertensive patients by assessing zinc levels in serum, urine and monocytes.

METHODS

Patients with newly diagnosed essential hypertension were randomly divided into two treatment groups: those treated with captopril only (n = 16) and those treated with enalapril only (n = 18). Ten healthy subjects served as controls. Prior to the start of treatment and again 6 months later, zinc was assessed in the serum, in urine collected over 24 hours, and in peripheral blood monocytes.

RESULTS

Significant enhancement of 24-hour urinary zinc excretion (micrograms/24 hour) after 6 months of treatment was observed only in the captopril-treated group (p < 0.01). However, intramonocytic zinc levels decreased significantly in both of the treated groups over the same period (p < 0.01 and P < 0.04 in the captopril- and enalapril-treated groups, respectively).

CONCLUSION

Treatment of hypertensive patients with captopril or enalapril may result in zinc deficiency.

Bereavement is associated with time-dependent decrements in cellular immune function in asymptomatic human immunodeficiency virus type 1-seropositive homosexual men

Seventy-nine human immunodeficiency virus type 1 (HIV-1)-seropositive homosexual men participating in a longitudinal study of HIV-1 infection were assessed twice, 6 months apart, to investigate associations between bereavement and cellular immune function. Subjects were assessed by using a theory-driven model comprising life stressors, social support and coping style, and control variables. Natural killer cell cytotoxicity was decreased among the bereaved at both times. Lymphocyte proliferative response to phytohemagglutinin was decreased among the bereaved at the second time point but not at the first. These functional immune decrements are associated with increased neuroendocrine responses of the sympathetic adrenomeduallary system as well as the limbic-hypothalamic-pituitary-adrenal axis. Implications for differential neuroendocrine responses over time are discussed. Active coping style was independently and positively related to both immune measures. The results imply that a bereavement support group intervention merits investigation for an effect on immunological measures and clinical progression of HIV-1 infection as well as grief resolution.

Zinc exchange by blood cells in nearly physiologic standard conditions

Determination of zinc concentrations in white blood cells has been used to establish zinc deficiency. During pathological conditions changes in zinc concentrations in these blood cells were observed. However, these investigations were hampered by the low amount of zinc in this form per mL blood. Earlier we demonstrated that, in the case of zinc deficiency, the uptake of zinc was increased, using the in vitro exchange of zinc by the various blood cells with extracellular zinc labeled with 65Zn in fairly physiologic conditions. In case of inflammation, no increase in zinc uptake by erythrocytes was seen, indicating that this method probably can be used to differentiate real from apparent zinc deficiency. Only during the first days of the inflammatory process, probably representing the redistribution phase during which zinc moves from the serum to the liver, a small increase in in vitro zinc uptake was seen in mononuclear cells (MNC) and polymorphonuclear cells (PMNC). Earlier papers raised some questions; e.g., is the uptake part of an exchange process and can the efflux of zinc by the cells be measured by the same method; what is the influence of time on the process of zinc uptake; what is the magnitude of the uptake of zinc by the cells compared to the zinc concentration in the cells; and, what is the influence of temperature on the uptake of zinc? In the present study, the influence of incubation time and temperature on the uptake of zinc by human and rat blood cells and on the release of zinc by rat blood cells was studied. At least three phases of uptake of zinc in the various cells were found by varying the incubation time--a fast phase during the first half hour, probably caused by an aspecific binding of zinc on or in the cell membrane; a second fast uptake between 60-330 min, probably caused by an influx of zinc in the cell as part of the exchange process of zinc; and a slow third phase after 5.5 h, in which probably the in- and efflux of the rapidly exchangeable intracellular pool is more or less equilibrated. For mononuclear cells, polymorphonuclear cells, and erythrocytes of rats, the rapidly exchangeable intracellular pool is 40%, 53%, and 10%, respectively, of the total zinc content of the cells. This study is also performed in human cells; in human cells the exchangeable pool of mononuclear cells and erythrocytes is 17 and 3.5% of the total zinc content of the cells, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Refrigeration of blood samples prior to separation is essential for the accurate determination of plasma or serum zinc concentrations

An evaluation of refrigeration (7 degrees C) to prevent falsely high plasma or serum zinc concentrations owing to elapsed time between blood collection and centrifugation was performed. At room temperature (23 degrees C), both plasma and serum zinc concentrations increased significantly, if blood samples were stored uncentrifuged. Plasma zinc concentrations increased 6.3% at 1 h and 40.7% at 24 h, whereas serum zinc concentrations increased only 0.9% at 1 h and 12.5% at 24 h at room temperature. When blood samples were stored uncentrifuged in the refrigerator for up to 24 h, there were no significant increases in zinc concentrations in either plasma or serum. These findings suggest that plasma or serum separation should be performed immediately after blood drawing to obtain accurate zinc concentrations, and if this is not feasible, the samples should be immediately refrigerated and separation performed within eight hours.

Zinc uptake by blood cells of rats in zinc deficiency and inflammation

In zinc deficiency, the function of leukocytes is impaired. However, the results of studies on the zinc concentration of blood cells in zinc deficiency are conflicting, probably in part because of technical and analytical problems. The aim of this study was to investigate, under standard conditions, the uptake of 65Zn-labeled zinc by blood cells, taken from zinc-deficient rats and from rats in which an inflammation is induced. In both conditions, the serum zinc concentration is reduced. In clinical practice, this makes it difficult to determine whether the decrease in serum zinc is the result of a real or an apparent zinc deficiency. In stress, like an inflammatory disease, the decrease of zinc reflects an apparent zinc deficiency because of redistribution of serum zinc into the liver and because of decrease in serum albumin concentration. Over 70% of the serum zinc is bound to albumin. Blood cells from zinc-deficient and control rats were isolated using a discontinuous Percoll gradient and incubated under nearly physiological conditions in a 65Zn-containing medium. A significant increase in the in vitro uptake of 65Zn-labeled zinc by the blood cells of zinc-deficient rats was seen: erythrocytes 1.3, mononuclear cells 2.0, and polymorphonuclear cells 2.6 times the control values. During inflammation, no change in 65Zn-labeled zinc uptake by erythrocytes and mononuclear cells was demonstrated after 2 d, although the serum zinc and albumin concentrations were decreased, but a small but significant increase in zinc uptake by polymorphonuclear cells was observed. This study of 65Zn uptake in vitro under standard conditions may prove of value for distinguishing in patients real zinc deficiency from apparent zinc deficiency owing to, e.g., stress, although additional experiments should be performed.

Active coping style is associated with natural killer cell cytotoxicity in asymptomatic HIV-1 seropositive homosexual men

The aim of this study was to examine the hypothesis that a psychosocial model was associated with natural killer cell cytotoxicity (NKCC) in HIV-1 infection. A sample of 62 HIV-1 seropositive homosexual men at CDC stages II and III were given a psychosocial battery assessing life stressors, social support, and coping style. A regression model quantifying these variables along with control variables for alcohol use, substance use and nutritional status was estimated. Active coping style was directly and positively associated with NKCC, and trends toward a negative relationship of life stressors and a buffering effect of social support on lives stressors were also observed. The results suggest that (1) control variables should be included with psychosocial models and that (2) psychosocial factors, especially active coping, may have a deterrent effect on loss of NK cell function. Active coping style may merit a specific focus in future research of life stressors and the immune system.

Erythrocytes, erythrocyte membranes, neutrophils and platelets as biopsy materials for the assessment of zinc status in humans

During a controlled zinc depletion-repletion study, fifteen men aged 25.3 (SD 3.3) years were fed on a low-Zn diet with high phytate:Zn and phytate x calcium:Zn molar ratios for 7 weeks, followed by a 2 week repletion period when 30 mg supplemental Zn/d was given. Changes in plasma, urine, and hair Zn concentrations, taste acuity, and cellular immune response confirmed the development of mild Zn deficiency. Zn concentrations in neutrophils, platelets, erythrocytes and erythrocyte membranes, mean platelet volume, and activities of alkaline phosphatase (EC 3.1.3.1) and alpha-D-mannosidase (EC 3.2.1.24) in neutrophils did not respond to changes in Zn status. In contrast, alkaline phosphatase activity in erythrocyte membranes showed a significant decline which was consistent in all subjects (nmol product formed/min per mg protein; baseline v. 7-week Zn depletion, 0.656 (SD 0.279) v. 0.506 (SD 0.230), at 7 weeks; P < 0.05); neutral phosphatase activity remained unchanged. Alkaline phosphatase activity in erythrocyte membranes may be a potential index of Zn status in humans.

Blood zinc status and zinc treatment in human immunodeficiency virus-infected patients

We investigated the zinc concentration in blood and the effect of zinc supplementation in 11 male outpatients seropositive for human immunodeficiency virus at stage 5 according to the Walter Reed classification. Zinc concentration was measured in serum, platelets, mononuclear and polymorphonuclear cells, and erythrocytes. There was a significant increase in serum zinc concentration after zinc administration, but the zinc level in blood cells remained unchanged. All patients showed a progressive gain in body weight and a slight elevation in levels of CD4+ cells. No adverse side-effects were noticed.

Interest of zinc determination in leucocyte fractions for the assessment of marginal zinc status

In order to test the sensitivity of leucocyte zinc determination in the assessment of zinc status, an isolation procedure of mononuclear (MNC) and polymorphonuclear (PMNC) cell fractions was developed. Zinc concentrations in cells from healthy subjects were (mean +/- SD, in mumol/10(10) cells): 0.81 +/- 0.24 in MNC and 0.55 +/- 0.06 in PMNC. In patients suffering from several diseases known to be associated with a marginal impairment in zinc status (cirrhosis, cancer, obesity, endocrine and rheumatic diseases), these concentrations did not differ from those in controls except in rheumatic patients in whom MNC zinc was increased (1.05 +/- 0.42 mumol/10(10) cells) and correlated with erythrocyte sedimentation rate (r = 0.41, P less than 0.01). This relation was also significant in the whole study population (r = 0.39, P less than 0.01). Leucocyte zinc therefore appears to have a limited value in the assessment of marginally impaired zinc status, except in inflammatory states.

Effects of one year of supplementation with zinc and other micronutrients on cellular immunity in the elderly

The objective of this study was to determine the effects of a year of Zn supplementation on Zn concentrations in circulating cells and on cellular immune functions in the elderly. Subjects, aged 60-89, were given a placebo, 15 mg Zn, or 100 mg Zn daily for 12 months. All subjects also received a multivitamin/mineral supplement that contained no additional Zn. Blood samples were drawn and immune functions assessed prior to and at 3, 6, 12, and 16 months after beginning Zn supplementation. Subject diets were also assessed at each visit. Dietary folate, pyridoxine, alpha-tocopherol, copper, zinc, and magnesium were consistently below recommended intakes. Although plasma Zn increased significantly in the 100 mg Zn treatment group, concentrations of Zn in erythrocytes, mononuclear cells, polymorphonuclear leukocytes, and platelets were not significantly increased by zinc supplementation. Natural killer cell activity was transiently enhanced by the 100 mg/day dose of Zn. There was a progressive improvement in delayed dermal hypersensitivity (DDH) and in lymphocyte proliferative responses to two mitogens; this may have been due to one or more components of the multivitamin/mineral supplement administered to all study subjects. The enhancement of DDH was significantly greater in the placebo group than in either zinc treatment group. Thus, zinc had a beneficial effect on one measure of cellular immune function while simultaneously having an adverse effect on another measure of cellular immunity.

Cimetidine and the immuno-response in healthy volunteers

We compared the immunologic measurements from treatment of 12 healthy volunteers (six male, six female) with 800 and 1,600 mg cimetidine. In the first trial 800 mg cimetidine was administered daily to the volunteers over a period of 7 d; after an interruption of 2 months, 1,600 mg of cimetidine was applied daily for 21 d. The most striking result of our study was an increased mitogen-induced lymphocyte proliferation. This conclusion can be drawn from the fact that phytohaemagglutinin (PHA) (0.4 microgram/well) and pokeweed mitogen (PWM) (0.4 microgram/well) induced lymphocyte proliferation were found to be significantly increased in comparison to pretreatment values on day 7 in both cimetidine regimens (800 mg; PHA: mean proliferation 66,500 before treatment to 166,00 cpm, PWM: mean proliferation 8,800 before treatment to 34,000 cpm; 1,600 mg; PHA; mean proliferation 48,700 before treatment to 81,600 cpm; PWM: mean proliferation 6,300 before treatment to 16,200 cpm). Increased mitogen-induced proliferation following cimetidine intake is of special interest because the mechanisms of this activation process are incompletely known. Lymphocyte proliferation response is dependent on the availability of extracellular calcium. The function of the other bivalent cations is unknown. We found that the extent of mitogen-induced lymphocyte proliferation correlates with cellular intralymphocytic zinc and magnesium amounts (coefficients of correlation [r]) (800 mg: PHA/Mg r = 0.84; PHA/Zn r = 0.86; PWM/Mg r = 0.88; PWM/Zn r = 0.87). Though the application of both cimetidine doses causes enhanced mitogen-induced lymphocyte proliferation on day 7, T lymphocytes with different phenotypic properties appear to be influenced by cimetidine. In the first dose regimen (800 mg) the number of the CD8 lymphocytes decreased significantly from 16.1% (365 cell/microliters blood) to 12.7% (264 cells/microliters blood) after 7 d of cimetidine intake. After the period of high-dose (1,600 mg) cimetidine administration (at day 21) numbers of CD4 lymphocytes were significantly increased from 41.5% (860 cells/microliters blood) to 56.3% (1,210 cells/microliters blood). Our results show that although different cimetidine doses obviously influence different cell types of healthy volunteers, the cellular mechanisms are the same, namely, a proliferation and an increased incorporation of magnesium and zinc in lymphocytes.

Zinc concentrations in pure populations of peripheral blood neutrophils, lymphocytes and monocytes

It is doubtful if the measurement of plasma or serum zinc is of value in assessing zinc status. Leucocyte zinc has been suggested as an alternative since it may be representative of tissue zinc stores; but in many studies poorly defined cell populations make interpretation difficult. This paper describes detailed techniques for the isolation and analysis of pure populations of neutrophils, lymphocytes and monocytes. Zinc concentrations (+/- 1SD) in normal subjects were 1.26 +/- 0.27 nmol/mg protein, 1.85 +/- 0.32 nmol/mg protein and 2.58 +/- 0.65 nmol/mg protein in neutrophils, lymphocytes and monocytes respectively. Fasting caused a significant decrease in neutrophil and lymphocyte zinc, and an increase in monocyte zinc. Supplementation of zinc-replete subjects with 135 mg zinc/day for 3 weeks had no significant effect on cellular zinc concentrations.

[Trace elements in artificial nutrition. Art and practice]

The trace elements known to be necessary for man are iron, zinc, copper, selenium, chromium, manganese, molybdenum, cobalt and iodine. This review article, which excludes iron, deals with the need for supplemental trace elements during artificial feeding, and the way they should be administered. The biological importance of these trace elements is argued on the basis of their biochemical involvement and the clinical pictures seen in accidental or experimental deficiency states. Assessing a patient's trace element status is rather difficult. The relative merits of different laboratory investigations is discussed: plasma, erythrocyte, capillary and urinary levels, specific enzyme activities, loading tests. The different situations when trace elements are required, assessing the amount needed and the possible toxic risks, are presented from a literature survey.

Appraisal of the methodology and applications for measurement of the zinc content of blood components as indicators of zinc status

Methods for the measurement of the zinc content of blood components (plasma, erythrocytes, platelets, mononuclear leukocytes, and polymorphonuclear neutrophils) as indicators of the zinc status of animals have been reviewed and evaluated. The values of plasma or serum zinc concentrations as indicators of zinc status in experimental animals or humans is questionable. Consequently, the zinc content of blood cellular components has been suggested as better indicators of zinc status. Methodological problems, such as incomplete cellular separation or zinc contamination, occur in some of the procedures applied to the quantitation of blood cellular component zinc. Specialized microprobe procedures involving, for example, proton-induced X-ray fluorescence, scanning ion technology, mass spectrometery, or laser microprobe mass analysis might be used to measure the absolute zinc level in individual cells subjected to minimal handling. Then, more conventional methods can be tested against the true standard. Nevertheless, there appears to be species differences in regard to the response of blood cellular zinc concentrations to dietary zinc deficiency. Blood cellular component zinc is conserved during severe zinc deficiency in the rat. In contrast, the zinc content of blood cellular components in humans may reflect the whole body zinc status.

Analysis and evaluation of zinc and copper in human plasma and serum

Recommendations for daily dietary intakes of copper and zinc have been made by the National Academy of Sciences during the last decade. As a result there is increasing interest in analytic techniques for accurate and precise assessment of these trace elements in human tissues, including blood. In addition, the importance of standardizing techniques for the collection, preparation, and analysis of biologic samples is now recognized. The necessity for preventing contamination or losses requires careful monitoring at each step, from collection to analysis. Likewise, precision and accuracy must be established for techniques and certified reference standards employed. The selection of an ideal anticoagulant for preparing plasma for copper and zinc analyses is receiving increased attention. The discrepancy observed regarding higher concentrations (10-15%) of zinc and copper in serum than citrated plasma remains to be resolved. Following analysis and summary of the data, interpretation of the results is of paramount importance. It must be remembered that abnormal plasma or serum zinc or copper concentrations do not necessarily reflect true aberrations in metabolism, since several conditions (disease and nondisease) can also influence these indices of trace element nutriture. Immediate attention must be given to advancing the concept that trace element analysis of biological materials requires special collection, storage, and analysis precautions.