Lower and Upper Critical Zinc Levels in Relation to Cotton Growth and Development

Solution culture experiments in the greenhouse were conducted to determine the lower and upper critical Zn levels relative to early cotton (Gossypium hirsutum L.) growth and development. Upland cotton ‘Coker 310’ was grown in nutrient solution with fourteen Zn levels ranging from 0 to 10,000 μg/liter. The plants were grown for 31 days, harvested and analyzed for Zn. At Zn levels of less than 20 μg/I, top dry weight, root dry weight, plant height, node number and squares produced were reduced as compared to plants supplied with adequate Zn. Toxicities were induced at 2000 μg/I and higher. Root dry weight was not influenced by Zn levels to 10,000 μg/I. The lower critical Zn levels where Zn is required at a minimum concentration for maximum growth were from 8 to 11 μg/I in blades 1 through 5, respectively. The upper critical Zn levels where maximum Zn concentration in blade tissue can be tolerated for maximum growth were from 130 to 300 μg/g for blades 1 to 5, respectively. Blade 3, the recently matured leaf, was selected as the representative tissue for analysis. The lower and upper critical Zn levels in blade 3 were 11 and 200 μg/g, respectively.     

Plasma Melatonin Levels in Relation to the Light-Dark Cycle and Parental Background in Domestic Pigs

To study porcine melatonin secretion in a stable environment 3 daytime (10.00 – 15.00) and 3 nighttime (22.00 – 03.00) plasma samples were collected by jugular venipuncture from 15 gilts, 16 sows, 3 boars and 48 piglets (24 females and 24 males from 8 litters) and analysed for melatonin content. Nighttime melatonin concentrations were higher than daytime melatonin concentrations (p < 0.001), whereas no effect of sampling order could be discerned. The 3 adult Hampshire boars had higher melatonin concentrations during the day and the night, than the 31 adult Yorkshire females (p < 0.05). There was no clear difference between gilts and sows in plasma melatonin. The gilts from one of the litters had higher plasma melatonin concentrations than the gilts in 3 other litters (p < 0.05). Among the 48 piglets, the increase of nocturnal melatonin secretion differed between litters (p < 0.01), whereas the influence of father was not quite significant (p = 0.12). No difference in daytime melatonin concentrations between litters could be found, and there was no difference in melatonin levels between the male and female piglets. In conclusion, this study demonstrates that domestic pigs express a nocturnal increase of melatonin secretion in a standard stable environment. For some animals the amplitude of nighttime melatonin secretion was very low, although always higher than the daytime base levels. Furthermore, the levels of nighttime melatonin secretion differed between litters, which suggests a genetic background.     

甲亢甲低患者肝纤维化指标检测的临床意义分析

目的：探讨甲状腺功能亢进（甲亢）、甲状腺功能减低（甲低）与肝纤维化指标的关系及其可能的机制。方法：采用放射免疫分析法（R1A）检测57例甲亢患者、43例甲低患者、39例甲亢治疗后甲状腺激素正常者和50例健康成人的血清Ⅳ型胶原（1V-C）、Ⅲ型前胶原（PCⅢ）、透明质酸（HA）、层粘连蛋白（LN）、T3、T4、FT3、FT4、TSH、TGA、TMA含量。结果：甲亢患者组血清中1V-C、PCⅢ含量比正常对照组及甲低患者组显著性增高（P〈0.05）;治疗后甲状腺激素下降,1V-C、PCⅢ含量也随之下降（与治疗前比较P〈0.01）;HA、LN在四组中无显著性差异（P〉0.05）,在甲亢治疗前后无显著性差异（P〉0.05）。各项肝纤维化指标与TGA、TMA的阳性率无关。结论：甲亢患者可有不同程度的肝功能损害,血清中甲状腺激素水平增高时,1V-C、PCⅢ水平也增高,在用1V-C、PCⅢ判断肝纤维化时应注意有无甲状腺疾病特别是甲亢。未发现HA、LN含量与甲状腺激素水平的关系。     

Zinc, Copper, and Selenium Tissue Levels and Their Relation to Subcutaneous Abscess, Minor Surgery, and Wound Healing in Humans

Trace element involvement in wounds left to heal by secondary intention needs clarification. We have previously reported faster healing of wounds following acute surgery compared with elective excision of pilonidal sinus disease. The effect of topical zinc on the closure of the excisional wounds was mediocre compared with placebo. In contrast, parenteral zinc, copper, and selenium combined appear effective for wound healing in humans. We have investigated zinc, copper, and selenium with respect to (a) impact of acute versus chronic pilonidal sinus and (b) regional concentrations within granulating wounds treated topically with placebo or zinc in 42 (33 males) pilonidal disease patients. Baseline serum and skin concentrations of copper correlated (r _S?=?0.351, p?=?0.033, n?=?37), but not of zinc or selenium. Patients with abscesses had elevated serum C-reactive protein (CRP) and copper levels (+29 %; p?<?0.001) compared with the elective patients consistent with the strong correlation between serum copper and CRP (r _S?=?0.715, p?<?0.0005, n?=?41). Seven days after elective surgery, serum CRP and copper levels were elevated (p?=?0.010) versus preoperative values. The copper concentration in wound edges was higher than in periwound skin (p?<?0.0005) and wound base (p?=?0.010). Selenium levels were increased in wound edge compared to wound base (p?=?0.003). Topical zinc oxide treatment doubled (p?<?0.050) zinc concentrations in the three tissue localizations without concomitant significant changes of copper or selenium levels. In conclusion, copper and selenium are mobilized to injured sites possibly to enhance host defense and early wound healing mechanisms that are complementary to the necessity of zinc for matrix metalloproteinase activity.     

Plasma Selenium, Zinc, Copper and Lipid Levels in Postmenopausal Turkish Women and Their Relation with Osteoporosis

It has been shown that the trace elements and lipids play role in the growth, development and maintenance of bones. We aimed to investigate serum selenium (Se), zinc (Zn), copper (Cu) and lipid (total cholesterol, triglyceride (TG), high density lipoprotein-cholesterol, low-density lipoprotein-cholesterol) levels in postmenopausal women with osteoporosis, osteopenia and in healthy controls, and to determine the relationship between Se, Zn, Cu and lipid parameters and bone mineral density (BMD). The study included 107 postmenopausal women; 35 healthy (group 1), 37 osteopenic (group 2) and 35 osteoporotic (group 3). The women in all three groups were carefully matched for body mass index (BMI). Serum concentrations of Se, Zn and Cu were measured by atomic absorption spectrophotometry. Plasma Se, Cu, Zn and lipid levels were similar in all groups (p?>?0.05). When we combined the women in each of the three groups, and considered them as one group (n?=?107) we found a positive correlation between BMI and lumbar vertebra BMD, femur neck BMD, femur total BMD; a positive correlation between TG and femur neck BMD, femur total BMD; a positive correlation between Zn and lumbar vertebra BMD (total T score) (p??0.05). Although BMI has a positive effect on BMD, trace elements and lipids, except Zn and TG, did not directly and correlatively influence BMD. Further studies are needed to clarify the role and relationship of trace elements and lipid parameters in postmenopausal osteoporosis.     

Leptin receptors,NPY, and tyrosine hydroxylase in autonomic neurons supplying fat depots in a pig

The goal of this study was to determine the immunohistochemical characteristics of peripheral adrenergic OBR-immunoreactive (OBR-IR) neurons innervating adipose tissue in a pig. The retrograde tracer, Fast Blue (FB), was injected into either the subcutaneous, perirenal, or mesentery fat tissue depots of three male and three female pigs each with approximately 50 kg body weight. Sections containing FB(+) neurons were stained for OBR, tyrosine hydroxylase (TH) or neuropeptide Y (NPY) using a double labeling immunofluorescence method. OBR, TH, and NPY immunoreactivities were present in the thoracic (T) and lumbar (L) ganglia of the sympathetic chain, as well as in the coeliac superior mesenteric ganglion (CSMG), inferior mesenteric ganglion (IMG), intermesenteric ganglia (adrenal-ADG, aorticorenal-ARG, and ovarian-OG or testicular-TG ganglion). These results indicate that, in addition to neuroendocrine functions, leptin may affect peripheral tissues by acting on receptors located in sympathetic ganglion neurons.     

Linking Zinc and Leptin in Chronic Kidney Disease: Future Directions

Anorexia is a common complication in patients with chronic kidney disease (CKD) and is associated with the development of malnutrition and an increased risk of mortality. Several compounds are linked to anorexia in these patients; however, the mechanisms are unknown. Zinc (Zn) deficiency is associated with decreased food intake and has been observed in CKD patients. In addition, leptin is an anorexigenic peptide, and patients with CKD present generally high levels of this hormone. Studies have suggested an association between Zn and leptin status in human and rats; however, the results are inconsistent. Some claimed that Zn supplementation does not change leptin release or that there is no significant relationship between Zn and leptin. Others have reported that Zn might be a mediator of leptin production. CKD patients have hyperleptinemia and hypozincemia, but the relationship between Zn deficiency and leptin levels in CKD patients has been poorly understood until now. The aim of this review is to integrate knowledge on leptin and Zn actions to provide a cohesive clinical perspective regarding their interactions in CKD patients.     

Leptin differentially regulates NPY and POMC neurons projecting to the lateral hypothalamic area.

Recent studies have reinforced the view that the lateral hypothalamic area (LHA) regulates food intake and body weight. We identified leptin-sensitive neurons in the arcuate nucleus of the hypothalamus (Arc) that innervate the LHA using retrograde tracing with leptin administration. We found that retrogradely labeled cells in the Arc contained neuropeptide Y (NPY) mRNA or proopiomelanocortin (POMC) mRNA. Following leptin administration, NPY cells in the Arc did not express Fos but expressed suppressor of cytokine signaling-3 (SOCS-3) mRNA. In contrast, leptin induced both Fos and SOCS-3 expression in POMC neurons, many of which also innervated the LHA. These findings suggest that leptin directly and differentially engages NPY and POMC neurons that project to the LHA, linking circulating leptin and neurons that regulate feeding behavior and body weight homeostasis.     

Salivary Melatonin in Relation to Depressive Symptom Severity in Young Adults

Reduced levels of melatonin have been associated with severe depression. The aim was to investigate the correlation between salivary melatonin and dimensional measures of depressive symptom severity in young adult psychiatric patients. Levels of melatonin were analyzed in six saliva samples during waking hours from 119 young adult patients under outpatient psychiatric care. Melatonin levels were tested for association with the severity of depressive symptoms using the self-rating version of the Montgomery Åsberg Depression Rating Scale (MADRS-S). Where possible, depressive symptoms were assessed again after 6±2 months of treatment. Response was defined as decrease in MADRS-S by ≥50% between baseline and follow-up. Patients with levels of melatonin in the lowest quartile at bedtime had an increased probability of a high MADRS-S score compared to those with the highest levels of melatonin (odds ratio 1.39, 95% CI 1.15–1.69, p<0.01). A post hoc regression analysis found that bedtime melatonin levels predicted response (odds ratio 4.4, 95% CI 1.06–18.43, p<0.05). A negative relationship between salivary melatonin and dimensional measures of depressive symptom severity was found in young patients under outpatient psychiatric care. Bedtime salivary melatonin levels may have prognostic implications.     

Zinc,Copper, Iron,and Selenium Levels in Brain and Liver of Mice Exposed to Acrylonitrile

The mechanism of toxicity of acrylonitrile (AN) has not been fully defined. The research described herein was undertaken to investigate the possible effects of AN on the levels of metallic elements in liver and brain of mice. Thirty-two mice were randomly assigned to four separate groups and treated intraperitoneal (i.p.) once daily for 1 week. Mice in the control group received normal saline, and mice in the three exposure groups received 5, 10, or 20 mg AN/kg b.w. Samples of brain and liver were collected immediately after decapitation. Tissue levels of trace elements (zinc, copper, iron) were determined with flame atomic absorption spectrophotometer or double channel atomic fluorescence absorption spectrophotometer (selenium). Mean brain weights of AN-treated mice were increased as a function of dose compared to controls, but there was no significant change in the ratio of liver/body weight in the four groups. While mean brain zinc decreased as a function of AN dosage, mean liver zinc of the low-dose group significantly increased (p < 0.05); mean liver copper in the medium-dose AN group was significantly higher compared to controls (p < 0.05); however, mean brain copper was increased, but the difference did not attain statistical significance in the three AN groups when compared with the controls (p > 0.05). Mean brain iron levels were significantly decreased in the middle-dose AN group (p < 0.05), but there were no consistent changes in liver iron. Tissue levels of selenium in brain and liver were similar for the control and AN treatment groups. AN induces significant and differential changes in the levels of zinc, copper, and iron in brain and liver. These changes likely play a pivotal role in mediating AN toxicity, most likely via changes in cellular redox status.     

Melatonin Ameliorates Cerebral Vasospasm After Experimental Subarachnoidal Haemorrhage Correcting Imbalance of Nitric Oxide Levels in Rats

In the present study, we investigated the in vivo effects of melatonin on SAH-induced cerebral vasospasm and oxidative stress, resulting from SAH in an experimental rat model. Twenty-eight rats (225–250 g) were divided into four groups equally: group 1; control, group 2; SAH, group 3; SAH plus placebo, and group 4; SAH plus melatonin. We used double haemorrhage method for SAH groups. Beginning 6 h after SAH, 20 mg/kg melatonin or equal volume of 0.9% saline was administered intraperitoneally twice daily for 5 days to groups 3 and 4, respectively. Melatonin or 0.9% saline injections were continued up to fifth day after SAH and rats were sacrificed at the end of this period. Brain sections at the level of the pons were examined by light microscopy. The lumen diameter and the vessel wall thickness of basilar artery were measured using a micrometer. The serum levels of cerebral vasodilator nitric oxide (NO), the brain levels of an intrinsic antioxidant superoxide dismutase (SOD) and a NO regulator arginase activities were measured. The brain levels of inducible nitric oxide (iNOS) and nitrotyrosine, a nitrosative stress parameter immunohistochemiacally determined. In conclusion, melatonin administration ameliorated cerebral vasospasm by increasing serum NO level and decreasing the brain the levels of arginase and oxidative stress. It is therefore possible that increased brain arginase activity after SAH may also have a significant role in the pathogenesis of vasospasm by limiting the availability of arginine for NO production.     

Serum Copper,Zinc, and Magnesium Levels in Patients with Chronic Fluorosis

Although there are many studies on effect of fluoride on trace elements in experimental animals, few studies exist on serum trace elements levels in patients with endemic fluorosis. We aimed to determine the serum levels of trace elements including serum copper (Cu), zinc (Zn), and serum levels of minerals including calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K) in patients with endemic fluorosis. The study group consisted of 30 patients with endemic fluorosis (17 females, 13 males, mean age 33.53 ± 9.85 years). An age, gender, and body mass index matched 30 healthy volunteers comprised control group (21 females, ten males with a mean age 33.93 ± 7.39 years). Urine fluoride levels of chronic fluorosis patients were significantly higher than that of control subjects as expected (1.92 ± 0.10 mg/l vs. 0.41 ± 0.09 mg/l, respectively; P < 0.001). Serum Cu levels (89.14 ± 16.77 μg/dL vs. 102.69 ± 25.04 μg/dL, respectively, P = 0.017), serum Zn levels (77.98 ± 20.58 μg/dL vs. 94.57 ± 35.87μg/dL, respectively, P = 0.032), and serum Mg levels (1.92 ± 0.18 mg/dL vs. 2.07 ± 0.31 mg/dL, respectively, p = 0.022) was significantly lower in chronic fluorosis patients than in controls. There were no statistically significant differences between the fluorosis group and control group with respect to serum levels of Na, K, Ca, and P. We concluded that chronic fluorosis is associated with reduced serum levels of Cu, Zn, and Mg.     

Plasma Levels of Zinc,Copper, Copper/Zinc Ratio,and Activity of Carbonic Anhydrase in Equine Piroplasmosis

We have determined the plasma concentrations of copper, zinc, copper/zinc ratio, and carbonic anhydrase activity in horses infected with Babesia equi. The study was conducted in 14 horses with the disease and 10 healthy animals that served as controls. The infection was confirmed by the clinical manifestations of the disease and by Giemsa staining of thin blood smears showing the parasites inside red blood cells. The horses with piroplasmosis had lower plasma levels of zinc, elevated copper, and increased activity of carbonic anhydrase. Consequently, the copper/zinc ratio was also higher than in the healthy controls.     

Serum Zinc and Copper Levels in Ischemic Cardiomyopathy

Changes in the copper (Cu) and zinc (Zn) concentrations have been reported previously in ischemic cardiomyopathy (ISCMP). Due to controversial results, the aims of this study were to compare levels of Cu, Zn, and Zn/Cu ratio of ISCMP patients with healthy volunteers and also to investigate the possible relationship between trace elements status in ISCMP patients with the severity of clinical disease based on the New York Heart Association (NYHA) classification. The subjects of this study consisted of 30 ISCMP and 27 healthy volunteers. ISCMP was diagnosed with a history of previous myocardial infarction and also coronary artery disease was confirmed by coronary angiography. Exclusion criteria were renal or hepatic insufficiency, alcohol usage, and intake of supplements containing Cu or Zn within 1 week. Cu and Zn levels have been assayed with atomic absorption spectrophotometry. Statistical analysis was performed with the SPSS 10 software using independent sample t test for comparing the levels of Cu and Zn between ISCMP and normal subjects. The mean Cu level of the ISCMP group (1.54 ± 0.52 mg/L) was significantly more than the Cu levels of the healthy volunteers (1.31 ± 0.24 mg/L; p = 0.048). The mean Zn levels of the ISCMP and healthy volunteers were 1.05 ± 0.28 and 1.12 ± 0.42, respectively, without any significant difference between groups. There was a trend for higher Cu level, lower Zn level, and lower Zn/Cu ratio in NYHA III patients in comparison with NYHA II group. Considering the results of this study, Cu may have a role in the development of ISCMP. Interventions such as administration of Cu chelators to relieve the symptoms or to decrease the progression of ISCMP is needed to be examined in large clinical trials. In this study, the Zn level of ISCMP patients was not significantly different in comparison with the healthy volunteers.     

The Effect of Low Dose Zinc Supplementation to Serum Estrogen and Progesterone Levels in Post-menopausal Women

The objective of the present study is to investigate how low-dose zinc supplementation for 2 weeks in the post-menopausal period influences levels of estrogen and progesterone in the serum. The study registered 32 natural menopause patients, who were allocated to four groups with equal number of patients. Group 1, control group, which was not subjected to any procedure. Group 2, the group that was supplemented with 15 mg/day zinc sulfate for 2 weeks. Group 3, the group that was given hormone replacement therapy (0.625 mg estrogen?+?5 mg medroxyprogesterone acetate/day) for 2 weeks. Group 4, the group that received hormone replacement therapy (0.625 mg estrogen?+?5 mg medroxyprogesterone acetate/day) and zinc sulfate (15 mg/day) for 2 weeks. Blood samples were collected twice from each subject, once at the beginning of the study, and once at the end of the 4-week procedure to determine estrogen (E2) and progesterone levels. Variance analysis was employed in the statistical evaluation of data. Level of significance was set at p?<?0.05. No significant difference was found between the estrogen and progesterone levels of groups 1 and 2. Groups 3 and 4 had higher estrogen and progesterone levels than groups 1 and 2 (p?<?0.05). Estrogen and progesterone levels in groups 3 and 4 were not different. Results of the study show that low-dose zinc supplementation to post-menopausal women for 2 weeks does not have a significant effect on the concerned parameters.     

Zinc Signaling in the Hippocampus and Its Relation to Pathogenesis of Depression

Zinc is released from glutamatergic (zincergic) neuron terminals in the brain, followed by the increase in Zn²⁺ concentration in the intracellular (cytosol) compartment as well as that in the extracellular compartment. Intracellular Zn²⁺ concentration mainly increases through calcium-permeable channels and serves as Zn²⁺ signal as well as extracellular Zn²⁺ concentration. Hippocampal Zn²⁺ signaling may participate in synaptic plasticity such as long-term potentiation and cognitive function. On the other hand, subclinical zinc deficiency is common in the old who might be more susceptible to depression. Zinc deficiency causes abnormal glucocorticoid secretion and increases depression-like behavior in animals. Neuropsychological symptoms are observed prior to the decrease in Zn²⁺ signal in the hippocampus under zinc deficiency. This paper summarizes that hippocampal Zn²⁺ signaling serves to maintain healthy brain and that glucocorticoid signaling, which is responsive to zinc homeostasis in the living body, is linked to the pathophysiology of depression.     

Plasma Zinc,Copper, and Serum Thyroid Hormones and Insulin Levels After Zinc Supplementation Followed by Placebo in Competitive Athletes

Intense physical activity is associated with biological adaptations involving hormones and trace elements. Zinc supplementation may affect plasma copper concentration, thyroid-stimulating hormone (TSH), thyroid hormones, insulin, and glucose homeostasis, but data in athletes are scarce. The aim of this study was to evaluate in competitive athletes (cyclists, n = 7, 32 ± 8 years) the effect of zinc supplementation (22 mg/day as zinc gluconate) during 30 days, and discontinuation using placebo (maltodextrin) during the following 30 days, on plasma zinc and copper concentrations, serum thyroid hormones, insulin and glucose levels, and HOMA2-IR. Compared to baseline, plasma zinc and Zn:Cu plasma ratio increased, but plasma copper decreased after zinc supplementation (day 30) and discontinuation (day 60) (p < 0.05). Zn supplementation and discontinuation had no effect on TSH, T3, and T4. Fasting serum insulin and HOMA2-IR increased (27% and 47%, respectively) on day 60 compared to baseline (p = 0.03), suggesting a delayed effect of zinc supplementation. Moreover, plasma zinc was positively associated with serum insulin (r = 0.87, p = 0.009) and HOMA2-IR (r = 0.81, p = 0.03) after zinc supplementation (day 30), indicating that supplemental zinc may impair glucose utilization in cyclists.     

Changes in Serum Zinc Levels Associated with Giardiasis and Dietary Zinc Intake in Mice

The association of giardiasis with the malabsorption of zinc remains controversial. This study investigated changes in serum zinc levels in Giardia-infected mice subjected to different dietary zinc regimens. Thirty-five mice (strain C₃H/H_eJ) were randomly categorized into two groups. The first group was inoculated with 5 × 10⁶ Giardia trophozoites (n = 18), and the second group remained Giardia free (n = 17). Each group (Giardia infected and Giardia free) was randomly classified into three subgroups and given low (9 mg Zn/kg), normal (33 mg Zn/kg), and high levels (288 mg Zn/kg) of dietary zinc over a 2-week period for acclimation. Fourteen days post-Giardia infection, all of the mice were euthanized and blood samples were collected. The number of trophozoites was quantified (hematocytometer), and serum zinc levels were determined via atomic absorption spectrophotometry. Significant increases in the median weights were only found in the Giardia-free mice (p < 0.05). A higher final median weight was found in the Giardia-free group when compared with that of the Giardia-infected group given low dietary zinc (p = 0.013). In the Giardia-infected group with low dietary zinc, the geometric mean of trophozoites was 3,498 ± 101 (SE) per milliliter. The Giardia-infected group had lower serum zinc levels than did the Giardia-free group with the high dietary zinc regimens (p < 0.05). Our results are consistent with studies among human populations, but further studies are required to elucidate the actual mechanism governing the zinc–giardiasis interaction.