Equivalent uptake of organic and inorganic zinc by monkey kidney fibroblasts, human intestinal epithelial cells, or perfused mouse intestine

Zinc (Zn) is recognized as an essential nutrient, and is added as a supplement to animal and human diets. There are claims that zinc methionine (ZnMet) forms a stable complex that is preferentially transported into tissues, and this has contributed to uncertainty about conflicting reports on the bioavailability of various Zn compounds. This study evaluated the cellular and intestinal uptake of inorganic and organic forms of Zn. Steady-state uptake of⁶⁵Zn by human intestine epithelial cells, and monkey kidney fibroblasts was not significantly different with zinc chloride (ZnCl₂), ZnMet, or zinc propionate (ZnProp) (P > 0.05). Uptake of⁶⁵Zn from zinc chelated with EDTA was significantly lower (P < 0.01). In live mice,⁶⁵Zn uptake by perfused intestine and deposition in intestine and liver showed no significant difference between ZnCl₂ and ZnMet. Equimolar [⁶⁵Zn]methionine and zinc[³⁵S]methionine were prepared according to a patented method that yields “ complexed” Zn. Cellular uptake of the radiolabeled methionine was <0.1% of the radiolabeled Zn from these complexes, indicating separate uptake of the Zn and methionine. Gel filtration did not distinguish between⁶⁵Zn in ZnCl₂, ZnProp, or reagent ZnMet, though feed-grade ZnMet containing >10% protein did give a higher-mol-wt form of⁶⁵Zn. Results of this study show equivalent uptake of Zn from inorganic and organic compounds, and support recent feed trials on Zn bioavailability.     

Effect of organic zinc supplementation on growth, nutrient utilization and mineral profile in lambs

To study the efficacy of organic zinc (Zn) supplementation on growth, nutrient utilization and mineral profile as compared to inorganic source [zinc sulphate (ZnSO₄)], 18 Muzaffarnagari male lambs of 11.30 ± 0.45 kg mean body weight (4–5 months of age) were divided into three groups of six animals in each in a randomized block design. Lambs in the control group were fed a standard total mixed ration (TMR) consisted of 60 kg/100 kg of concentrate mixture (CM) and 40 kg/100 kg of wheat straw. CM was consisted of 300 g/kg crushed maize grain, 270 g/kg soybean meal, 400 g/kg wheat bran, 20 g/kg mineral mixture (without Zn) and 10 g/kg common salt. Animals in the experimental groups were additionally supplemented with 20 mg Zn/kg of diet either through inorganic (ZnSO₄) or organic [Zn-methionine AA complex (Zn-meth)] sources. Experimental feeding was done for a period of 150 days including a 6 days metabolism trial. The intake of dry matter (DM), organic matter (OM), crude protein (CP), digestible CP and total digestible nutrients and digestibility of DM, OM, CP, ether extract, neutral detergent fibre and hemicellulose were comparable (P>0.05) among the three groups. However, digestibility of cellulose and acid detergent fibre was significantly (P<0.05) higher in Zn-meth group as compared to control group. Though the balance of calcium was adversely affected (P<0.01) in both the Zn supplemented groups, but it was significantly higher in Zn-meth group compared to ZnSO₄ group. While apparent absorption and retention of nitrogen, phosphorus, copper, iron and manganese were similar (P>0.05) among different groups, retention of Zn (P<0.05) as well as its concentration in the serum (P<0.01) were highest in Zn-meth group, followed by ZnSO₄ group and lowest in the control group, suggesting higher bioavailability of Zn from Zn-meth as compared to ZnSO₄. Average daily gain of the lambs and feed conversion efficiency were also significantly (P<0.05) higher in Zn-meth group as compared to control and ZnSO₄ groups, suggesting a positive role of organic zinc supplementation on the performance of lambs.     

Effects of Zinc Glycine Chelate on Oxidative Stress,Contents of Trace Elements,and Intestinal Morphology in Broilers

Three hundred and sixty healthy Ross × Ross 1-day-old broilers were used to study the effects of zinc glycine chelate (Zn-Gly) on oxidative stress, contents of trace elements, and intestinal morphology. All broilers were randomly assigned to six treatment groups, which replicates three times. Diets were as follows: (1) control (containing 29.3 mg zinc (Zn)/kg basic diet (0–21 days) and 27.8 mg Zn/kg (22–42 days)); (2) basic diet plus 30 mg Zn/kg from Zn-Gly; (3) basic diet plus 60 mg Zn/kg from Zn-Gly; (4) basic diet plus 90 mg Zn/kg from Zn-Gly; (5) basic diet plus 120 mg Zn/kg from Zn-Gly; and (6) positive control, basic diet plus 120 mg Zn/kg from zinc sulfate (ZnSO₄). The results showed that the addition of 90 or 120 mg/kg Zn-Gly led to an improvement of activity of Cu/Zn superoxide dismutase and glutathione peroxidase and a reduction of malondialdehyde content in livers at 21 and 42 days. With 90 mg/kg Zn-Gly, the content of sera zinc increased by 17.55% (P < 0.05) in 21-day broilers and 10.77% (P > 0.05) in 42-day broilers compared with that of the control. Adding 120 mg/kg Zn-Gly or ZnSO₄ to broilers' diets greatly enhanced the content of zinc in feces at 21 days (P < 0.05) and at 42 days (P < 0.05). For 42-day chickens, increased villus height and decreased crypt depth of the jejunum could be observed in the second growth stage of broilers fed with 90 mg/kg Zn-Gly. Also, intestinal wall thickness decreased (P < 0.05). In addition, adding 90 mg/kg Zn-Gly to the diet markedly elevated villus length of duodenum and decreased crypt depth of ileum (P < 0.05) in 42-day broilers.     

A Pilot Study on Zinc Levels in Patients with Rheumatoid Arthritis

The aim of the study was to evaluate zinc levels in three biological compartments (serum, erythrocytes and hair) in patients with rheumatoid arthritis (RA) as compared to healthy individuals. Zinc levels in serum, erythrocytes and hair (in 74 patients with RA and 30 healthy individuals) were assessed by atomic absorption spectroscopy. The mean hair zinc content was significantly lower in RA patients as compared to healthy individuals (p < 0.001). Moreover, a positive correlation was observed in the RA patient group between the erythrocyte zinc levels and the prednisone dose (r _s = 0.48, p < 0.05), and a negative correlation was found in this population between the serum zinc levels and disease duration (r _s = −0.42, p < 0.0006). In conclusion, it seems that hair may be a useful complementary study material for evaluating “zinc status” in rheumatoid arthritis patients.     

Zinc sources for rice in soil at different moisture regimes and organic matter levels

Summary Laboratory incubation experiment was conducted with a clay loam alluvial lowland rice soil to study the relative effectiveness of two sources of Zn (ZnEDTA and ZnSO₄) in maintaining Zn availability in soil under two moisture regimes (saturated and waterlogged) both in presence as well as absence of added organic matter. The results showed that ZnEDTA was always more effective than ZnSO₄ in maintaining higher amount of zinc in available form in soil for a longer perid. Results of greenhouse experiment conducted with rice showed that concentration and uptake of Zn by roots were generally higher with ZnEDTA than with ZnSO₄ both in presence and absence of added organic matter, whereas in respect of shoot this was true only in absence of added organic matter.     

Influence of zinc on soluble carbohydrate and free amino acid levels in rapeseed plants regenerated in vitro in the presence of zinc

To gain more insight into the impact of zinc on the primary metabolites in rapeseed, plants were regenerated in vitro in the presence of zinc (0.1–1 mM), acclimatized, transferred to a greenhouse, and treated with 2 mM ZnSO₄. The main metabolites, including soluble carbohydrates and free amino acids, were analyzed by nuclear magnetic resonance spectroscopy, and further confirmed by spectrophotometry and enzymatic analyses. Exposure of these greenhouse-grown plants to ZnSO₄ led to both a significant rise of the total amino acid level and an increase of proline accumulation in the different tissues. Moreover, the control plants, regenerated without zinc stress, exhibited a significant reduction of soluble carbohydrate levels, whereas the plants derived from Zn-treated regenerants exhibited significantly higher levels of both glucose and sucrose. These levels increased proportionally with the Zn concentration in the regeneration step.     

Correlation Between Dietary Zinc Intakes and Its Serum Levels with Depression Scales in Young Female Students

It has been suggested that mood disorders and depressive status may be accompanied by lowered zinc status in the body, and adequate consumption of zinc increases a general perceived well-being. The main objective of this study was to assess the correlation between serum zinc concentrations and dietary zinc intakes with depression scores in university female students. In the first phase, Beck's depression questionnaire was applied in a random sampling of 308 selected 20–25-year-old female students (one third of total students in Ahvaz Jondi-Shapour University of Medical Sciences Golestan dormitories) to assess the major depressive disorder (MDD) scales. Then, in the second phase, 23 students who identified as having moderate and severe depression were selected as the case group, and 23 healthy age matched were chosen as the controls. Each of them completed a 12-item semiquantitative food frequency questionnaire containing the main food sources of zinc in the usual dietary patterns and also a 24-h food recall questionnaire to assure the daily zinc intakes. Daily zinc intakes were obtained by multiplying each portion size by its zinc content using food tables. A 5-ml blood sample was taken for further serum zinc status using flame atomic absorption spectrophotometry technique. Pearson's r was used to show the correlation between quantitative variables. Both daily zinc intake and serum zinc concentrations of MDD group were about two thirds of healthy index (p < 0.01). Depressed individuals used to eat lower servings of red meats and chicken as the main food sources of zinc in students' usual diets (p < 0.001). Consumption of other foods as the sources of zinc was not significantly different in two groups. A linear significant correlation between dietary zinc intakes and its serum levels was seen in samples (r = 0.62; p < 0.001) and MDD students (r = 0.55; p < 0.001). There was a linear inverse correlation between Beck questionnaire scores and serum zinc concentrations in all of the investigated students(r = -0.65; p < 0.001) and MDD girls (r = −0.71; p < 0.001). Beck questionnaire scores and diatary zinc intakes were also inversly correlated (r = −0.58; p < 0.001). However, no statistical correlation was seen between these two variables in MDD cases. In depressed female students, dietary zinc intake is correlated to its serum concentrations; however, the serum zinc levels are inversely correlated to depression scales. Consumption of the main dietary sources of zinc such as red meats and chicken should be encouraged in young depressed girls.     

Metabolism and Tissue Distribution of Trace Elements in Broiler Chickens' Fed Diets Containing Deficient and Plethoric Levels of Copper,Manganese, and Zinc

Supplementation of broiler diets with copper, manganese, and zinc at levels higher than that stipulated by the National Research Council 1994 reportedly improved live weight, feed conversion, and cured leg abnormality supposedly caused by inadequate intake of Mn and Zn. The objective of the study was to ascertain the effects of plethoric supplementation of copper (Cu), manganese (Mn), and zinc (Zn) on performance and metabolic responses in broiler chickens. The study also aimed to discriminate the responses of the birds when the mineral elements were supplemented either in an inorganic or in an organic form. Cobb 400 broiler chickens (1-day old, n = 300) were assigned to three dietary treatments each containing nine replicates with ten birds for 39 days. The treatments included a control in which the diet was devoid of supplemental trace elements and treatments supplemented with an inorganic trace element premix (ITM) and supplemented with a combination of the inorganic and an organic trace element premix (OTM). The ITM contained (per kilogram) copper, 15 g; iron, 90 g; manganese, 90 g; zinc, 80 g (all as sulfated salts); iodine (as potassium iodide), 2 g; and selenium (as sodium selenite), 0.3 g. The OTM on the other hand, contained copper, 2.5 g; iron, 15 g; manganese, 15 g; zinc, 13.33 g; and chromium, 0.226 g (all as protein chelates). Plethoric supplementation of trace elements improved live weight gain and feed/gain ratio (p < 0.05). Leg abnormality developed in the 16% of the control group of birds but not in the supplemented group. Metabolizability of dry matter, organic matter, and protein was higher (p < 0.01) in the ITM and OTM groups. Excretion of Cu, Fe, and Zn decreased (p < 0.1) due to supplementation of the trace elements leading to increased apparent absorption of the said mineral elements (p < 0.01). Concentration of the concerned trace elements in serum, liver, and composite muscle samples was higher (p < 0.05) in the ITM and OTM dietary groups indicating an increased deposition of the said mineral elements due to supplementation. Although the study revealed subtle difference between the inorganic and organic mineral premixes with regards to the parameters mentioned above, it became apparent that it is possible to reduce excretion of these trace elements by a judicious escalation in the level of supplementation. The results of the present investigation further revealed that the trace mineral requirement of broiler chickens suggested by the National Research Council may not be optimum to support the maximum growth potential of the high yielding strains, and it is reasonable to consider a review of the current NRC recommendations to meet the needs of the modern birds.     

Effect of zinc-amended poultry manure and zinc sulphate on the growth and uptake of zinc by corn (Zea mays L.)

Summary A greenhouse experiment conducted to study the effect of different levels of Zn supplied through Zn-amended poultry manure and ZnSO₄ on corn (Zea mays L.) indicated that both the sources significantly increased the dry matter yield and uptake of zinc. The zinc amended poultry manure at all levels of zinc application was more effective than ZnSO₄ in this respect. The percent zinc in corn derived from the fertilizer and percent utilization of applied zinc from the Zn-amended poultry manure was higher than that from ZnSO₄ when applied at equivalent levels.     

Effect of different zinc sources and levels on inhibition of the apoptosis induced by glucocorticoid of thymocytes in vitro

This experiment was conducted to investigate the effects of zinc sulfate and zinc methionine (Zn-Met) and their levels on apoptosis induced by glucocorticoid of thymocytes and the possible mechanism. Dexamethasone was used to make the apoptosis model of thymocytes; zinc sulfate and zinc methionine were supplemented to the medium at levels of 0,50, 100, 500, and 1000 μM. The activity of cells,Cu,Zn superoxide dismutase (Cu,Zn-SOD), DNA ladder pattern, intracellular calcium concentration, and the percentage of apoptosis nuclei were determined. Both ZnSO₄ and Zn-Met could modulate apoptosis; they inhibited apoptosis and decreased DNA fragmentation. The regulation was concentration dependent. At levels of 50 and 100 μM, the effect of Zn-Met on inhibiting apoptosis was less efficient than that of ZnSO₄ (p<0.05), but the activity of the cells cultured with Zn-Met was higher than those cultured with ZnSO₄; they showed no difference in modulating apoptosis when added at levels of 500 and 1000 μM to the medium (p>0.05). Intracellular calcium concentrations of cells cultured with Zn-Met were higher than those cultured with ZnSO₄ at the same levels. Zinc supplementation decreased the concentration of intracellular calcium significantly (p<0.05) and increased the activity of Cu,Zn-SOD in the extract of the cells (p<0.05). Both zinc sulfate and Zn-Met could modulate apoptosis of thymocytes induced by glucocorticoid; the mechanism might involve the exchange of intracellular calcium, the redox of cells, and the two forms of zinc might go different ways in the regulations.     

In vitro studies on active calcium absorption from ovine rumen

From various in vivo and in vitro studies it has been shown that the rumen represents a significant site of Ca²⁺ absorption in sheep and goats. It was the aim of the present study to further characterize the underlying mechanisms. Unidirectional flux rates of Ca²⁺ across rumen wall epithelia of sheep were measured in vitro by applying the Ussing-chamber technique in the absence of electrochemical gradients. Under these conditions, significant Ca²⁺ net flux rates (J_net) clearly indicate the presence of active mechanisms for Ca²⁺ transport. Short chain fatty acids (SCFAs) caused highest stimulation of Ca²⁺ J_net (6.3 ± 1.9 nmol · cm⁻² · h⁻¹) when used as a mixture of acetate, proprionate and butyrate in physiological proportions (36, 15, 9 mmol · l⁻¹, respectively). The effect of 30 mmol · l⁻¹ butyrate (3.2 ± 0.6 nmol · cm⁻² · h⁻¹) was higher than respective amounts of propionate and acetate (0.6 ± 0.8 nmol · cm⁻² · h⁻¹ and 0.9 ± 0.8 nmol · cm⁻² · h⁻¹, respectively). Eliminating SCFAs resulted in Ca²⁺ J_net of 0.4 ± 1.1 nmol ^. cm^−2 .h⁻¹. Addition of Ca channel blocker verapamil (mucosal 1 mmol · l⁻¹) had no significant effect on SCFA-stimulated J_net of Ca²⁺, whereas application of Na⁺/H⁺ inhibitor amiloride (mucosal 1 mmol · l⁻¹) further enhanced the Ca²⁺ J_net by >65%. The Ca²⁺-pump inhibitor vanadate had no significant effect on J_net of Ca²⁺. Dietary Ca depletion enhanced calcitriol plasma concentrations but had no effect on active Ca²⁺ absorption across the rumen wall of sheep. In addition, no effect on active Ca²⁺ absorption could be observed during early lactation. In conclusion, there is clear evidence for the rumen as a main site for active Ca²⁺ absorption in sheep. Our results suggest the presence of a Ca²⁺/H⁺ exchange mechanism in the apical membrane of rumen epithelial cells which depends on SCFA absorption and which does not seem to be under the control of calcitriol. Basolateral Ca²⁺ extrusion occurs independently from Ca²⁺-pump activity and may be accomplished via Na⁺/Ca²⁺ exchange. Accepted: 29 June 1999     

In vitro studies on calcium absorption from the gastrointestinal tract in␣small ruminants

Unidirectional flux rates of Ca²⁺ across gastrointestinal tissues from sheep and goats were measured in vitro by applying the Ussing-chamber technique. Except for the sheep duodenum, mucosal to serosal Ca²⁺ flux rates (J _ms) exceeded respective flux rates in the opposite direction (J _sm) in both species and in all segments of the intestinal tract. This resulted in net Ca²⁺ flux rates␣(J _net = J _ms − J _sm) ranging between −2 and 9 nmol · cm⁻² · h⁻¹ in sheep and between 10 and 15 nmol cm⁻² · h⁻¹ in goats. In sheep, only J _net in jejunum, and in goats, J _netin duodenum and jejunum were significantly different from zero. Using sheep rumen wall epithelia, significant J _net of Ca²⁺ of around 5 nmol · cm⁻² · h⁻¹ could be detected. Since the experiments were carried out in the absence of an electrochemical gradient, significant net Ca²⁺ absorption clearly indicates the presence of active mechanisms for Ca²⁺ transport. Dietary Ca depletion caused increased calcitriol plasma concentrations and induced significant stimulations of net Ca²⁺ absorption in goat rumen. J _net of Ca²⁺ across goat rumen epithelia was significantly reduced by 1 mmol · l ⁻¹ verapamil in the mucosal buffer solution. In conclusion, there is clear evidence for the rumen as a main site for active Ca²⁺ absorption in small ruminants. Stimulation of active Ca²⁺ absorption by increased plasma calcitriol levels and inhibition by mucosal verapamil suggest mechanistic and regulatory similarities to active Ca²⁺ transport as described for the upper small intestines of monogastric species. Accepted: 31 July 1996     

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.     

Inorganic nutrient manipulation for highly improved <Emphasis Type="Italic">in vitro</Emphasis> plant regeneration in finger millet—<Emphasis Type="Italic">Eleusine coracana</Emphasis> (L.) Gaertn.

Summary Growth and morphogenesis of plant tissues under in vitro conditions are largely influenced by the composition of the culture media. In this study, effects of different inorganic nutrients (ZnSO₄ and CuSO₄) on callus induction and plant regeneration of Eleusine coracana in vitro were examined. Primary callus induction without ZnSO₄ resulted in improved shoot formation upon transfer of calluses to normal regeneration medium. CuSO₄ increased to 5x the normal concentration in the media for primary seed callus induction and plant regeneration resulted in a 4-fold increase in number of regnnerated shoots. For long-term callus cultures, 2x KNO₃ or 4x Fe-EDTA could replace the requirement for α-naphthaleneacetic acid in the regeneration medium, while 60 μM ZnSO₄ or 0.5 μM CuSO₄ was optimal for plant regeneration from callus cultures.     

The relative efficiency of zinc carriers on growth and zinc nutrition of corn

Summary A comparison of different zinc carriers showed that application of Zn-DTPA, Zn-EDTA, Zn-fulvate and ZnSO₄ significantly increased the dry matter yield and zinc uptake by corn over the control treatment where no zinc was applied. The chelates in particular enhanced to a greater extent the uptake of both native and applied sources than that observed with ZnSO₄ as the zinc carrier. Both the dry matter yield and zinc uptake by corn showed a positive and significant relationship with self-diffusion coefficient of zinc showing thereby that diffusion contributed mainly the supply of Zn from the ambient soil matrix to plant roots. The effectiveness of the chelates varied depending on their capacity to retain Zn in a soluble form in the soil solution.It is evident that zinc nutrition of plants in alkaline and calcareous soils can be more effectively regulated by both synthetic and natural chelates or organic manures which contain substantial amount of complexed zinc.Journal Paper No. 1 from the Department of Soil Science and Agric. Chemistry, Tirhut College of Agriculture, Dholi, Muzaffarpur, Bihar, India.     

Effects of Different Levels of Organic and Inorganic Chromium on Growth Performance and Immunocompetence of Broilers under Heat Stress

This experiment was carried out to investigate the effects of different levels of organic and inorganic chromium on the performance, immune function and some serum mineral concentrations of broilers under heat stress condition (23.9–37°C cycling). A total of 150 one-day-old broiler chicks according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Chicks were fed on corn–soybean meal basal diets with added different concentrations of chromium (0, 600 and 1,200 μg kg⁻¹ chromium chloride or 600 and 1,200 μg/kg chromium l-methionine) from 1 to 49 days of age. Humoral immunity was assessed by intravenous injection of 7% sheep red blood cell (SRBC) followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed by the cutaneous basophil hypersensitivity (CBH) test to phytohemagglutinin (PHA)-P at day 32 and PHA-M at day 48. Heterophil/lymphocyte (H/L) ratio was also measured as a reliable indicator of stress. The body mass, feed intake and conversion ratio were not influenced by dietary chromium (P > 0.05). Dietary supplementation of both organic and inorganic chromium significantly increased primary and secondary antibody responses (P < 0.01), and also improved H/L ratio (P < 0.05), CBH response (P < 0.01) as well as relative weights of thymus (P < 0.05) and spleen (P < 0.01). Both dietary organic and inorganic chromium caused an increase in serum concentrations of Cr and Zn (P < 0.01), but decreased the serum concentration of Cu (P < 0.01). These results suggest that supplemental chromium especially in organic form offers a good management practice to reduce heat stress-related depression in immunocompetence of broiler chicks.     

Zinc Nutritional Status in Adolescents with Down Syndrome

Studies have evidenced that zinc metabolism is altered in presence of Down syndrome, and zinc seems to have a relationship with the metabolic alterations usually present in this syndrome. In this work, the Zn-related nutritional status of adolescents with Down syndrome was evaluated by means of biochemical parameters and diet. A case–control study was performed in a group of adolescents with Down syndrome (n = 30) and a control group (n = 32), of both sexes, aged 10 to 19 years. Diet evaluation was accomplished by using a 3-day dietary record, and the analysis was performed by the NutWin program, version 1.5. Antropometric measurements were performed for evaluation of body composition. The Zn-related nutritional status of the groups was evaluated by means of zinc concentration determinations in plasma and erythrocytes, and 24-h urinary zinc excretion, by using the method of atomic absorption spectroscopy. The diet of both groups presented adequate concentrations of lipids, proteins, carbohydrates, and zinc. The mean values found for zinc concentration in erythrocytes were 49.2 ± 8.5 μg Zn/g Hb for the Down syndrome group and 35.9 ± 6.1 μg Zn/g Hb for the control group (p = 0.001). The average values found for zinc concentration in plasma were 67.6 ± 25.6 μg/dL for the Down syndrome group and 68.9 ± 22.3 μg/dL for the control group. The mean values found for zinc concentration in urine were 244.3 ± 194.9 μg Zn/24 h for the Down syndrome group and 200.3 ± 236.4 μg Zn/24 h for the control group. Assessment of body composition revealed overweight (26.7%) and obesity (6.6%) in the Down syndrome group. In this study, patients with Down syndrome presented altered zinc levels for some cellular compartments, and the average zinc concentrations were low in plasma and urine and elevated in erythrocytes.     

Effects of Progesterone, β-Estradiol,and Androsterone on the Changes of Inorganic Element Content in Barley Leaves

The present study was performed to determine the changes in inorganic element content in barley leaves of mammalian sex hormones (MSH). Barley leaves were sprayed with 10⁻⁴, 10⁻⁶, 10⁻⁹, 10⁻¹², 10⁻¹⁵ M concentrations of progesterone, β-estradiol, and androsterone at 7th day after sowing. The plants were harvested at the end of 18 days after treatment with MSH solutions. The inorganic element concentrations were determined using wavelength dispersive X-ray fluorescence spectroscopy technique. Although the all MSH concentrations significantly (p < 0.05) increased the concentrations of calcium, magnesium, phosphorus, sulfur, copper, manganese, aluminum, zinc, iron, potassium, and chlorine, it decreased those of sodium concentration in barley leaves. The maximum changes in the element concentrations were obtained at 10⁻⁹ M for plant leaves treated with progesterone, 10⁻⁶ M for plant leaves treated with β-estradiol and androsterone. The present study elucidated that MSH significantly (p < 0.05) affected the inorganic element concentrations in barley leaves.     

Reef framework diagenesis across wave-flushed oxic-suboxic-anoxic transition zones

 The temporal and spatial variability of inorganic nutrient concentrations in overlying- and interstitial-seawater in Checker Reef, Oahu was examined for response to incident wave magnitude and direction. Well-point samplers were used to profile interstitial nutrient concentrations across oxic-suboxic-anoxic transition zones in the upper meter of the reef framework at four sites aligned across the patch reef. Samples were acquired over February, 1992, during which time dominant E-NE trade winds directed waves across the reef from the fore-reef to back-reef. However, W-SW “Kona” winds periodically interrupted this pattern and directed waves in the reverse direction. The interstitial microbial habitats of fore- and back-reef framework were distinct from those within the mid-reef framework. Maximum concentrations of PO₄, Si, and NH₄ in interstitial waters occurred at framework depths of 1–2 m, with the highest concentrations occuring within the mid-reef framework. Maximum concentrations of NO₃ and NO₂, which were used to delineate the core of the suboxic zone, occurred at framework depths of 5–10 cm at all stations and attained 2–4 fold higher peak concentrations within the mid-reef and back-reef than within the fore-reef. Variability in interstitial nutrient concentrations was greatest within the back-reef and is consistent with reversals of wave-direction, with the resultant increases in mixing between interstitial and overlying seawater due to flushing caused by the S-SW Kona wind events. The ratio of molar concentrations of total inorganic nitrogen to phosphate (TIN : PO₄) for the fore-reef was 5 : 1; while ratios for the mid- and back-reef were 13–15 : 1, reflecting that the dominant source of particulate organic matter to the fore-reef framework is plankton, while that of the mid- and back-reef is benthic reef plants. Accepted: 4 May 1999