Clinical implications of trace elements in endocrinology

Paediatric HIV: Correlation between Serum Zinc Levels and CD4 Percentage on Asymptomatic Nigerian Children Living with HIV

OBJECTIVE

This study was conducted to determine the relationship between their serum zinc levels and the CD4% in a cohort children living with HIV.

METHODS

One hundred asymptomatic, anti-retroviral Therapy (ART) naïve children living with HIV (participants) aged 5-60 months who were enrolled into the Paediatric HIV clinic of The University of Nigeria Teaching Hospital were recruited in the study over a 10-month period. Blood samples were collected in the morning from non-fasting participants and serum zinc levels were analysed using Atomic Absorption Spectrophotometer. The CD4% was ascertained using the CD4% easy count kit on the Partec® Cyflow Counter machine. Data were analysed using Statistical Package for the Social Sciences version 19.

RESULT

The median (IQR) serum zinc level for the participants was 55.5 µg/dl (49.75) while their median (IQR) CD4% was 27.79% (18.67). Males had a median (IQR) CD4% of 24.29% (19.10) which was significantly lower than those of females [32% (20.59) (p = 0.047)]. No significant relationship was found between CD4% and zinc levels among the subjects (r = -0.061, p = 0.557).

CONCLUSION

Serum zinc levels of asymptomatic ART naïve children living with HIV have no relationship with their CD4%.

The first insight into the trace element status of human adrenal gland accompanied by elemental alterations in adrenal adenomas

BACKGROUND

The baseline status of trace metals in adrenal tissue is unresolved, while the elemental profile for any adrenal pathology has not been examined so far. This study aimed to determine the baseline status of important toxic (Ni, As, Cd, Pb, Th, U) and essential trace elements (Mn, Co, Cu, Zn, Se) in healthy adrenal tissues (HATs) as well as to examine whether there are alterations in the elemental composition of adenomatous adrenal tissues (AATs). Furthermore, this study aimed to find potential trace metals that could play a role in the pathogenesis of adrenal adenoma (AA).

METHODS

The study included 45 patients diagnosed with AA. Impacts of relevant parameters such as gender, age, smoking habits and nodular sizes were considered. All samples were subjected to microwave digestion and the trace elements were determined by inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

This is the first study that provided an insight into the elemental status of HATs. It was also shown that AATs had altered trace metal contents. Compared to HATs, the most significant findings were related to the high content of essential (Cu, Mn, Se, Zn) and Pb as a non-essential metal. Although gender, age and smoking habits had a modest effect on metal profiles, the most significant alterations were related to the nodular diameter above 4 cm, indicating that the growth of benign tumor could influence changes in elemental composition.

CONCLUSION

For the first time the baseline contents of essential and toxic trace metals in HATs were determined. The results of this study may highlight the role of toxic and essential trace metals in AAs and could provide new insights into the molecular basis of pathophysiological changes caused by the hazardous effects of trace metals on adrenal structure and function.

Serum Zinc Levels in Apparently Healthy Children in Nigeria: Are They Acceptable

Introduction:

Despite the importance of zinc in the human body, there is paucity of data on the zinc status of Nigerian children. The aim of this study was to determine the serum zinc levels of children attending the pediatric outpatient clinic of a tertiary hospital in South East Nigeria and to assess their need for routine zinc supplementation.

Materials and Methods:

One hundred children aged 5–60 months were recruited consecutively from the pediatric outpatient clinic. Their socioeconomic class (SEC) was assessed using the tool developed by Oyedeji. Physical examination was carried out to exclude malnutrition and/or liver disease. Samples were collected in the morning from nonfasting subjects and were analyzed using atomic absorption spectrophotometer. Serum zinc deficiency was defined as zinc level <80 μg/dl.

Results:

The overall median (range) serum zinc level was 83.3ug/dl (60–105 μg/dl) while the median (mean rank) serum zinc levels among male and female subjects were 83.4 μg/dl and 84.2ug/dl, respectively (U = 1071.00; P = 0.228). A total of 26 (26%) apparently healthy children had low serum zinc levels. There was no association between gender and serum zinc levels (χ² = 2.163; P = 0.141). A significant positive but weak relationship was found between SEC and zinc levels (r = 0.208, P = 0.038) but not between serum zinc levels and age of the children (r = 0.185, P = 0.065).

Conclusion:

A significant proportion of Under-5s could have low serum zinc levels. Routine zinc supplementation may be necessary among this age group in Nigeria.

Correlations between Basal Trace Minerals and Hormones in Middle and Long-Distance High-Level Male Runners

Several essential trace minerals play an important role in the endocrine system; however, toxic trace minerals have a disruptive effect. The aim of this research was to determine basal concentrations and the possible correlations between trace minerals in plasma and several plasma hormones in runners. Sixty high-level male endurance runners (21 ± 3 years; 1.77 ± 0.05 m; 64.97 ± 7.36 kg) participated in the present study. Plasma hormones were analyzed using an enzyme-linked immunosorbent assay (ELISA) and plasma trace minerals were analyzed with inductively coupled plasma mass spectrometry (ICP-MS). Correlations and simple linear regression were used to assess the association between trace minerals and hormones. Plasma testosterone concentrations were inversely correlated with manganese (r = -0.543; β = -0.410; p < 0.01), selenium (r = -0.292; β = -0.024; p < 0.05), vanadium (r = -0.406; β = -1.278; p < 0.01), arsenic (r = -0.336; β = -0.142; p < 0.05), and lead (r = -0.385; β = -0.418; p < 0.01). Plasma luteinizing hormone (LH) levels were positively correlated with arsenic (r = 0.298; β = 0.327; p < 0.05) and cesium (r = 0.305; β = 2.272; p < 0.05), and negatively correlated with vanadium (r = -0.303; β = -2.467; p < 0.05). Moreover, cortisol concentrations showed significant positive correlations with cadmium (r = 0.291; β = 209.01; p < 0.05). Finally, insulin concentrations were inversely related to vanadium (r = -0.359; β = -3.982; p < 0.05). In conclusion, endurance runners living in areas with high environmental levels of toxic minerals should check their concentrations of anabolic hormones.

Serum trace elements are interrelated with hormonal imbalance in men with acute ischemic stroke

The objective of the present study was to assess hormonal and trace element status in men suffering from acute ischemic stroke.

METHODS

21 acute ischemic stroke patients and 21 age- and body mass index-matched healthy volunteers were enrolled in the study. Serum trace elements were assessed using inductively coupled plasma mass spectrometry. Serum hormones and brain damage markers were estimated using enzyme-linked immunosorbent assay.

RESULTS

Ischemic stroke patients are characterized by significantly higher levels of total and free triiodothyronine (T₃), anti-thyroid peroxidase antibodies (Anti-TPO-Ab), prolactin, and cortisol, whereas the level of thyroid stimulating hormone (TSH) was decreased. Serum B, Cu, Li, Mn, Ni, Pb, Se, V, and Zn in stroke significantly exceeded the control values, whereas the level of Co and Fe was decreased. Correlation analysis revealed a significant association between serum B and T₃, Anti-TPO-Ab, and iodine concentration; serum Li and Sr levels - with circulating TSH, free T3, and Anti-TPO-Ab; and V concentration - with total T₃ and I levels. The following positive relationships were also revealed: Co - TSH, Mn - free T₃, Zn - free T₃. Multiple linear regression demonstrated that Co, I, and Li were directly related to circulating TSH levels, whereas V concentration was negatively interrelated. In turn, only serum Li levels were characterized by a significant direct relationship with free T3 values.

CONCLUSION

Generally, the obtained data demonstrate that altered serum trace elements are associated with thyroid dysfunction in acute ischemic stroke patients. However, the causal relationship should be estimated.

The variation of macro- and micro-minerals of tissues in diabetic and non-diabetic rats

This study determined the levels of Ca, Mg, Fe, Zn, Cu, and Na in various tissues samples (liver, brain, kidney, intestines, muscle and hair) of diabetic and non-diabetic rats by flame atomic absorption spectroscopy, in order to assess the role of element levels during T2DM. The ratios of Ca/Mg, Zn/Cu, Ca/Zn, and Mg/Zn in diabetic and non-diabetic rat tissues were also calculated. The determined element levels were further subjected to a student-t test statistical analysis and multiple-linear-regression in order to evaluate similarities, differences, and an inter-element association in tissues of diabetic and non-diabetic rats. The results of the study showed high variability in element levels and Ca/Mg Zn/Cu Mg/Zn Ca/Zn ratios in the tissues of diabetic and non-diabetic rats, but are tissue- and element-dependent, suggesting differences in the accumulation of the elements in tissues of diabetics and non-diabetics. The obtained significant differences in the levels of elements and Ca/Mg Zn/Cu Mg/Zn Ca/Zn ratios in several tissues of diabetic and non-diabetic rats in this study suggest that the investigated elements play considerable roles in the T2DM disease process. Strong inter-element associations (R²≥0.9) were observed for some elements in tissues of diabetic and non-diabetics rats. However, poor inter-elemental associations were obtained for some elements in the tissues of diabetic and non-diabetic rats.

Serum Trace Element Profiles, Prolactin, and Cortisol in Transient Ischemic Attack Patients

The primary aim of the present study was to assess the association between trace element status, brain damage biomarkers, cortisol, and prolactin levels in transient ischemic attack (TIA) patients. Ten male and 10 female TIA patients were involved in this study. Age, gender, and BMI-matched volunteers served as the respective control group. Serum samples were examined for complement components C4 and C3a, vascular endothelial growth factor (VEGF), S100B, NR2 antibodies (NR2Ab), total antioxidant status (TAS), cortisol, and prolactin. Trace element concentration in serum samples was assessed using inductively coupled plasma mass spectrometry at NexION 300D. The obtained data indicate that both male and female TIA patients were characterized by the increased C4 and prolactin concentrations. At the same time, serum VEGF levels were elevated in only men, whereas TAS values were decreased in women with TIA. Serum cortisol concentrations were significantly increased only in female TIA patients. Men and women with TIA were characterized by a 32 and 44 % decrease in serum Fe content. A two- and threefold increase in serum V content was observed in TIA females and males, respectively. Women with TIA had 60 % higher values of serum B, whereas male patients were characterized by a sevonfold increase in boron content in comparison to the control values. TIA also resulted in decreased serum Cu content in women and elevation of I, Li, Mn, Se, Zn, As, Pb, Ni, and Sr levels in men. Correlation analysis revealed a significant association between trace elements concentration and the studied parameters.

Trace elements profile is associated with insulin resistance syndrome and oxidative damage in thyroid disorders: Manganese and selenium interest in Algerian participants with dysthyroidism

The relationship between dysthyroidism and antioxidant trace elements (ATE) status is very subtle during oxidative stress (OS). This relationship is mediated by thyroid hormone (TH) disorder, insulin resistance syndrome (IRS) and inflammation. The aim of this study was to investigate ATE such as selenium (Se), manganese (Mn), zinc (Zn) and copper (Cu) status on thyroid dysfunction, and their interaction with antioxidant enzyme activities, mainly, superoxide dismutase (SOD) and glutathione peroxidase (GPx), TH profile (TSH, T(3), T(4)) and IRS clusters. The study was undertaken on 220 Algerian adults (30-50 years), including 157 women and 63 men who were divided to 4 groups: subclinical hypothyroidism (n = 50), overt hypothyroidism (n = 60), Graves's disease hyperthyroidism (n = 60) and euthyroid controls (n = 50). The IRS was confirmed according to NCEP (National Cholesterol Education Program). Insulin resistance was evaluated by HOMA-IR model. Trace elements were determined by the Flame Atomic Absorption Spectrometry (Flame-AAS) technique. The antioxidant enzymes activity and metabolic parameters were determined by biochemical methods. The TH profile and anti-Thyroperoxidase Antibodies (anti-TPO-Ab) were evaluated by radioimmunoassay. Results showed that the plasma manganese levels were significantly increased in all dysthyroidism groups (p ≤ 0.01). However, the plasma copper and zinc concentrations were maintained normal or not very disturbed vs control group. In contrast, the plasma selenium levels were highly decreased (p ≤ 0.001) and positively correlated with depletion of glutathione peroxidase activity; and associated both with anti-TPO-Ab overexpression and fulminant HS-CRP levels. This study confirms the oxidative stress-inflammation relationship in the dysthyroidism. The thyroid follicles antioxidant protection appears preserved in the cytosol (Cu/Zn-SOD), while it is altered in the mitochondria (Mn-SOD), which gives this cell organelle, a status of real target therapy in thyroid dysfunction. The publisher would like to apologise for any inconvenience caused. [corrected].

An evidence-based systematic review of vanadium by the Natural Standard Research Collaboration

An evidence-based systematic review of vanadium by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated, reproducible grading rationale. This article includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Thyroid disorders-assessments of trace elements, clinical, and laboratory parameters

The trace elements studied in this work (Se, Cu, Zn) are the essential constituents or cofactors required to activate numerous enzymes and proteins, playing crucial role in various physiological processes. The disturbed levels of abovementioned elements may adversely affect the endocrine system, resulting in various thyroid disorders among other upsets. The aim of this study was to investigate possible associations between them and parameters of redox balance, thyroid function indices as well as clinical records (duration of disease and therapy, lag time between thyroid surgery and this study examination, LT4 dosage) in patients with different thyroid disorders, including malignant diseases of the gland. In the group of patients with papillary carcinoma, we found a statistically significant higher Cu concentration compared with controls and patients with Hashimoto disease. In the same groups, the parameter of Zn/Cu ratio demonstrated reciprocally arranged statistically significant differences. For the group of papillary cancer patients, there was a negative correlation between lag time since thyroid operation and GPX3 activity. Our data support hypothesis of indirect involvement of Zn and Cu in thyroid regulation. For selenium, lack of simple correlation between its serum level and thyroid indices implies the need for further research on other selenium status parameters more adequately depicting changes in endocrine system.

Speciation of iodine in high iodine groundwater in china associated with goitre and hypothyroidism

Iodine intake affects the occurrence of disease in a population. Excessive iodine intake may be caused by a high iodine content of drinking water. Tap water in few locations in Europe contains up to 139 microg/L mostly bound to humic substances, probably leaching from marine sediments in the aquifers. Even higher iodine contents have been found in Chinese waters, previously shown to associate with goitre and hypothyroidism. The aims were to elucidate speciation of high iodine groundwater from deep wells in China and to compare with high iodine waters from Europe. Water was sampled from eight wells in five villages along Bohai Bay, China. Macro-molecules and low molecular weight (MW) substances were separated by size exclusion chromatography (high performance liquid chromatography, Superose 12 HR 10/30, buffer 0.1 M Tris, pH 7.0). Organic material was evaluated by A280 and iodine in fractions measured by the Ce/As method after alkaline incineration. Iodine content of well water varied from 135 to 880 microg/L (median 287 microg/L). The amount of organic material in water was low with A280, <1-5 mAU. The chromatographic traces were similar between samples: One peak of iodine eluted around K (AV) 0.65 corresponding to MW 5 kDa (humic substances) and one peak at V (total) (iodide/low MW substances). The fraction of iodine in macro-molecules, suggested to be humic substances, varied from 8% to 70% (median 27%). Iodine and peak absorbance were associated (p = 0.006). In conclusion, iodine in iodine-rich deep well water in northern China may have marine origin and may associate with humic substances, comparable to shallow well iodine-rich water in Europe. High iodine intake from iodine-rich water suggests the cause of endemic goitre and hypothyroidism in some areas in China being iodine.

Inhibition by Selenium Compounds of Catecholamine Secretion Due to Inhibition of Ca2+ Influx in Cultured Bovine Adrenal Chromaffin Cells

Selenium is an essential trace metal element, whereas large doses of selenium exert adverse effects to the human body. We examined the effects of selenium compounds, sodium selenite (Na2SeO3) and sodium selenate (Na2SeO4), on catecholamine secretion from cultured bovine adrenal chromaffin cells. Treatment of chromaffin cells with sodium selenite for 72, 48, and 24 h caused decreases in protein and catecholamine contents, in association with cell damage, at concentrations over 30, 300, and 300 microM, respectively. The cells treated with subtoxic conditions (<100 microM, 48 h) of sodium selenite were used for further experiments. Sodium selenite treatment for 48 h inhibited carbachol (CCh)-induced catecholamine secretion in a concentration-dependent and non-competitive manner, while it did not affect high K+- and veratridine-induced catecholamine secretion. Sodium selenite (100 microM) did not affect CCh- and veratridine-induced 22Na+ influx, while the compound inhibited 45Ca2+ influx induced only by CCh, but not high K+ and veratridine. Sodium selenate even at higher concentrations (1000 microM) did not affect any stimulus-induced catecholamine secretion and 45Ca2+ influx. Thus, sodium selenite may specifically exert adverse effects, such as inhibition of physiological stimulus-induced catecholamine secretion from adrenal chromaffin cells due to inhibition of Ca2+ influx.

Trace elements in human physiology and pathology: zinc and metallothioneins

Zinc is one of the most abundant nutritionally essential elements in the human body. It is found in all body tissues with 85% of the whole body zinc in muscle and bone, 11% in the skin and the liver and the remaining in all the other tissues. In multicellular organisms, virtually all zinc is intracellular, 30-40% is located in the nucleus, 50% in the cytoplasm, organelles and specialized vesicles (for digestive enzymes or hormone storage) and the remainder in the cell membrane. Zinc intake ranges from 107 to 231 micromol/d depending on the source, and human zinc requirement is estimated at 15 mg/d. Zinc has been shown to be essential to the structure and function of a large number of macromolecules and for over 300 enzymic reactions. It has both catalytic and structural roles in enzymes, while in zinc finger motifs, it provides a scaffold that organizes protein sub-domains for the interaction with either DNA or other proteins. It is critical for the function of a number of metalloproteins, inducing members of oxido-reductase, hydrolase ligase, lyase family and has co-activating functions with copper in superoxide dismutase or phospholipase C. The zinc ion (Zn(++)) does not participate in redox reactions, which makes it a stable ion in a biological medium whose potential is in constant flux. Zinc ions are hydrophilic and do not cross cell membranes by passive diffusion. In general, transport has been described as having both saturable and non-saturable components, depending on the Zn(II) concentrations involved. Zinc ions exist primarily in the form of complexes with proteins and nucleic acids and participate in all aspects of intermediary metabolism, transmission and regulation of the expression of genetic information, storage, synthesis and action of peptide hormones and structural maintenance of chromatin and biomembranes.

Zinc supplementation decreases total thyroid hormone concentration in small ruminants

The effect of dietary zinc (Zn) supplementation on plasma Zn and serum thyroid hormones was evaluated in healthy male Merino lambs and Angora goats. A total of 12 lambs and 12 goats were divided into two equal groups as control and Zn groups in separate experiments. The lambs and goats of the control groups were fed basal rations alone. The Zn contents of these rations prepared for lambs and goats were 40 mg/kg and 35 mg/kg in dry matter (DM), respectively. Both species of animals in the Zn groups were fed a basal ration supplemented with zinc sulphate adjusted to 250 mg Zn/kg diet in DM. The feeding trial lasted for 12 weeks in lambs and 8 weeks in goats. Blood samples were taken from the jugular vein at 4-week intervals. Both animal species in the Zn groups had higher plasma Zn values than the controls throughout the experimental period, except in the 4th week in goats. However, the levels of serum total thyroxine (T4) and triiodothyronine (T3) were lower in the lambs and goats of the Zn groups, except in the 4th week, as compared to those in the controls. Moreover, serum total thyroid hormone levels of the goats were higher at the 4th week than at the 8th week. Although there was a decrease in the levels of free thyroxine and triiodothyronine of both small ruminant species in the Zn groups when compared to the controls, these alterations were not statistically significant. These results may show that zinc supplementation to the diet at this dose reduces total thyroid hormone levels in small ruminants but does not yet impair the euthyroid status of the organism.

Serum trace elements in animal models and human depression: Part III. Magnesium. Relationship with copper

In the present study we report the results of investigations into the serum magnesium levels in a clinical study of 19 patients with unipolar depression; 16 normal controls and in three animal models of depression: chronic severe stress (CSS), chronic mild stress (CMS) and olfactory bulbectomy (OB) in rats. There was no alteration in the values found in the rat models of depression. Unipolar depressed patients exhibit significantly lower serum magnesium levels than the appropriate controls (depression 19.1+/-2.2 mg/l; control 21.0 mg/l). There is no correlation between serum magnesium levels and the severity of depression. A significant positive correlation between serum magnesium/copper ratio and the severity of depression indicates a clear relationship between alterations of the homeostasis of these two ions in human depression. Copyright 2000 John Wiley & Sons, Ltd.

Zinc sulfate supplementation improves thyroid function in hypozincemic Down children

In subjects affected by trisomy 21 (Down syndrome), hypothyroidism is the most common endocrinological deficit. Plasma zinc levels, which are commonly detected below the normal range in Down patients, are related to some endocrinological and immunological functions; in fact, zinc deficiency has been shown to impair immune response and growth rate. Aims of this study were to evaluate (1) the role of zinc deficiency in subclinical hypothyroidism and (2) thyroid function changes in Down children cyclically supplemented with zinc sulfate. Inverse correlations have been observed between age and triiodotironine (T3) and between zinc and thyroid-stimulating hormone (TSH); higher TSH levels have been found in hypozincemic patients at the beginning of the study. After 6 mo of supplementation, an improvement of thyroid function (TSH levels: 3.96 +/- 1.84 vs 2.64 +/- 1.33 mUI/mL basally and after 6 mo, respectively) was observed in hypozincemic patients. In the second cycle of supplementation, a similar trend of TSH was observed. At the end of the study, TSH significantly decreased in treated hypozincemic subjects (4.48 +/- 1.93 vs 2.96 +/- 1.20 mUI/mL) and it was no longer different in comparison to normozincemic patients. We suggest zinc supplementation to the diet in hypozincemic Down children as a simple and useful therapeutic tool.

The effect of manganese supply on thyroid hormone metabolism in the offspring of manganese-depleted dams

The present study was performed to investigate the effect of manganese (Mn) supply on metabolism of thyroid hormones in the rat. A study with rats was carried out over two generations. Female rats were raised with a Mn-deficient diet (0.1 mg Mn/kg), and mated to produce a second generation. The male rats of the second generation were used as subjects for the investigation. They were divided into five groups and fed diets with Mn concentrations of 0.1, 0.5, 2.2, 10, and 46 mg/kg for 40 d. For assessment of thyroid hormone metabolism, concentrations of thyroid hormones in serum and activity of hepatic type I 5'deiodinase (5'D-1) were measured. Feeding diets with 0.1 mg Mn/kg impaired growth and food conversion, influenced parameters of thyroid hormone metabolism, and changed some clinical-chemical parameters, such as concentrations of total protein, albumin, calcium (Ca) and magnesium (Mg) as well as activity of alkaline phosphatase in serum. Regarding the thyroid hormone metabolism, rats fed the diet with a Mn level of 0.1 mg/kg had a higher 5'D-I activity in liver, and consequently a higher concentration of triiodothyronine in serum than the rats fed the other diets. In contrast, the concentrations of total and free thyroxine were not influenced by the Mn intake. Growth, clinical-chemical parameters, concentrations of thyroid hormones in serum, and activity of hepatic 5'D-I were similar in the rats fed diets with Mn concentrations between 0.5 and 64 mg/kg. The present study shows that feeding a diet with a very low Mn concentration affects growth and thyroid hormone metabolism and that a dietary level of 0.5 mg Mn/kg is adequate for growth and thyroid hormone metabolism in the offspring of Mn-depleted dams.

Concentrations of thyroid hormones in serum and activity of hepatic 5' monodeiodinase in copper-deficient rats

The aim of the present study was to investigate the effect of copper deficiency on thyroid hormone metabolism in rats. Therefore, an experiment with growing male Sprague-Dawley rats was carried out, consisting of two groups of rats fed either a copper-deficient (0.06 mg Cu/kg) or a copper-adequate diet (16 mg Cu/kg). Both groups of rats were fed identical quantities of diet by pair-feeding. Copper deficiency decreased the final body weight of the rats by 5% compared to copper-adequate control rats. A severe copper-deficient state in the rats fed the copper-deficient diet was proved by a large decrease of ceruloplasmin activity in serum (by 97%) and hematological changes. For estimation of thyroid hormone metabolism, the concentrations of total and free thyroxine (T4) and triiodothyronine (T3) in serum and the activity of hepatic 5'monodeiodinase (5'D) were determined. Copper-deficient rats had an increased concentration of T3 in serum, whereas the concentrations of total and free T4 as well as the activity of hepatic 5'D were not different compared with copper-adequate control rats. Therefore, the study shows that copper deficiency has only slight effects on thyroid hormone metabolism in growing rats.

Total body zinc depletion and its relationship to the development of hyperprolactinemia in chronic renal insufficiency

Modulation of free plasma zinc levels has been implicated in the increase in plasma prolactin levels seen in patients with chronic renal insufficiency (CRI). The relative importance of this mechanism in comparison to others, however, has not been elucidated. Zinc equilibrium between plasma and red blood cells is partly dependent upon red blood cell carbonic anhydrase (CA). In the present paper, we have investigated the interrelationships among total plasma zinc, leukocyte zinc, prolactin, and erythrocyte CA in patients with CRI. Uremic patients were shown to have significantly increased levels of plasma prolactin and erythrocyte CA activity when compared to normal controls. Moreover, red blood cell CA total concentration and isoenzyme-I and-II levels, as well as plasma zinc were found to be significantly decreased in uremic patients in comparison to normal controls. In patients with CRI, a negative correlation was demonstrated between erythrocyte CA catalytic activity and plasma zinc, as well as between plasma zinc and plasma prolactin levels. Moreover, leukocyte zinc content, which is a reliable indicator of total body zinc stores, was found to be significantly decreased in uremic patients when compared to normal controls. A strong negative correlation between leukocyte zinc content and plasma prolactin levels was documented in CRI patients. Our results suggest that alterations in erythrocyte CA levels, enzymatic activity or isoenzyme profile are most probably mechanistically and etiologically unrelated to the high plasma prolactin levels in CRI patients. Contrariwise, depletion of total body zinc stores, rather than redistribution of this trace metal among extracellular compartments, may represent one of the major contributing mechanisms leading to uremic hyperprolactinemia.

The relationship between insulin and vanadium metabolism in insulin target tissues

Vanadium (V) is an orally effective treatment for diabetes, but relatively little is known about the mechanisms controlling its normal metabolism nor the long term pharmacokinetics of oral administration. We have examined the accumulation of V in various organs from rats fed liquid diet for up to 18 days, containing no additional V, 1.6, 80, or 160 mumole/kg/day as either sodium orthovanadate (SOV) or vanadyl sulfate (VS). V content was assayed using a sensitive neutron activation analysis method. The organs of the nonsupplemented animals contained widely varying concentrations (ng of V/g dry tissue weight) with brain < fat < blood < heart < muscle < lung < liver < testes < spleen < kidney. All organs accumulated V in a dose dependent manner. Not all organs showed steady state amount of V at 18 days, so additional rats were fed SOV or VS, switched to control diet, and assayed at 0, 4 and 8 days. From this data we calculated organ half lives of V. Insulin sensitive tissue tissues, such as liver and fat, had shorter half-lives than tissues that are relatively less insulin sensitive, such as spleen, brain and testes. SOV and VS fed rats showed similar patterns, but VS had somewhat shorter t1/2's. Additional studies of old and young rats fed control diet for 45 days show accumulation of V in spleen and testes. These results indicate that vanadium metabolism varies widely among different organs, and that insulin, either directly or indirectly has effects on the retention of vanadium. This may have impact on the therapeutic use of vanadium in Type I diabetics with no insulin, or Type II patients who may be relatively hyperinsulinemic.

[Role of trace elements and vitamins in peri-operative nutrition]

The micronutriment requirements, whether trace elements (inorganic) or vitamins (organic), are tightly linked to the carbohydrate, lipid and protein metabolism, since they are involved in all metabolic pathways as cofactors. The micronutriments also have major immunological, endocrinological and antioxydant functions. Especially in the surgical patient, individual requirements may vary considerably and will be particularly increased in case of prior deficiency, anabolic states, or increased losses (burns, diarrhoea, gastric aspiration, intestinal fistulae, alcoholism, use of renal replacement techniques). In some of these settings, the micronutriment requirements will be independent from the macronutriments: this has been demonstrated for burns and intestinal fistulae. In the case of depletion prior to surgery, an isolated supplementation may be required without starting a proper nutrition. In general, micronutriment supplements will have to be started upon initiation of any artificial nutrition. After elective surgery and in absence of specific losses, the micronutriment requirements will be linked to the metabolic state of the patient and to the energy-protein intakes. This is most striking for the vitamin B group, where the requirements are indicated in mg per 1000 kcal. Vitamins A and E are also at risk in the surgical patient. Recommended micronutriment supplements have been revised in 1994. Some trace element deficiencies (Se, Cr, Mo) can initiate very serious complications and will require special caution in the perioperative period. Other deficiencies (Cu, Zn) result in more slowly evolving clinical pictures, with lesser life-threatening potential, resulting in infections and prolonged wound healing. In such cases, multi-elementary supplements are inadequate, and single element solutions supplements are required. All the micronutriments are characterized by a dose-response curve. The quantity avoiding biochemical dysfunctioning in human pathological situations has not yet been established, and it is unsatisfactory to merely compensate for the losses. This notion of biochemical dysfunctioning phase preceeding the clinical deficiency syndrome is in investigation for many nutriments, especially as the importance of some micronutriments, such as Se and vitamin E, in maintaining antioxidant defences is clearly established. The potential for preventing free radical induced overproduction of cytokines by means of nutritional strategy and enhanced antioxidant defences clearly exists, and is only at an early phase of investigation in patients. The future will be marked by the development of nutritional pharmacology based on pathology-specific micronutriment supplements.

Interval from calving to conception in high producing dairy cows treated with recombinant bovine somatotropin

Intervals from calving to conception in cows treated for two lactations with recombinant bST were ascertained using survival analysis methods. Daily intramuscular administration of placebo, 17.2, 51.6, or 86 mg of bST per cow started at d 70 postpartum and ended at culling or drying off. Breeding began at d 70 postpartum. Multiparous cows treated during the first lactation had significantly longer intervals from calving to conception. Cows treated during the previous lactation, but not during the second lactation, had significantly shorter intervals from calving to conception. Cox proportional hazards regression analysis was used with adjustment for the confounding effect of serum metabolites, milk production, energy balance, and body condition.

Plasma zinc and copper in Paris area preschool children with growth impairment

Plasma zinc, copper, and parameters of growth were measured in a group of 116 French preschool children, 2-5 yr-old from low-income households. Participants were selected on the basis of Z-scores of weight for height (WHZ) and height for age (HAZ). Zinc and copper concentrations of children with growth impairment (GI), defined by a WHZ and/or HAZ < -1 Z-score, were compared to those of age, sex, and ethnic origin matched controls (WHZ and HAZ > -1 Z-score). Mean (+/- SD) plasma zinc concentration was 12.58 +/- 1.84 mumol/L in the GI group, and 13.27 +/- 1.98 mumol/L in the controls. The difference of the means of paired samples was 0.69 +/- 2.34, and by paired t-test the significance reached p = 0.028. This effect was primarily a result of the weight retarded group (WHZ < -1 Z-score, p < 0.009) and to the girls (p < 0.05). There were no significant differences in plasma copper concentrations between groups. These results suggest the presence of marginal zinc deficiency in French preschool children with low weight for height Z-scores.