Influence of maternal dietary calcium levels on milk zinc, calcium and phosphorus contents and milk production in rats

The aim of this study was to analyze zinc (Zn), calcium (Ca) and phosphorus (P) contents in milk and the lactational performance in rats fed different Ca levels. Female Wistar rats were fed during pregnancy and lactation with experimental diets containing 20% protein and high (0.90%, HCa), normal (0.60%, NCa) or low (0.20%, LCa) Ca levels. Milk samples were collected after 15 days to determine the milk mineral composition. Pup weight was recorded from birth to weaning (litter size: 6-8 pups) to determine weight gain and calculate milk production. At delivery there were no significant differences in the body weight of the pups between the groups, but at day 15, the LCa group showed lower values than both NCa and HCa groups (p<0.05). The weight gain of the LCa group was significantly lower than of the HCa and NCa groups, between delivery and day 5 (p<0.05). This reduced rate of weight gain led to the LCa group reaching weaning weight later than the other groups. Milk production (g/pup/day) was significantly lower when dams were fed the LCa than the NCa and HCa diets (p<0.05). There were no significant differences among the groups in milk Ca, P and Zn levels and Ca/P ratio. The body mineral composition of the pups at birth did not differ between the groups; at weaning, however, both LCa and HCa groups had lower element contents than the NCa group (p<0.05). In conclusion, dams fed with a diet containing low Ca levels produced smaller volumes of milk and their pups reached weaning weights later than the other groups. As the milk mineral composition was not affected, it can be hypothesized that in dams fed low dietary Ca, the smaller milk yield might have been a way of maintaining milk quality. High Ca levels affected neither pregnancy outcome nor lactational performance.     

Effect of dietary protein level and source on bone mineralization in rats

Bone mineralization was studied in rats. Animals were divided into three feeding groups: LCP - diet with 13.5% crude protein in DM (5% of gluten, 10% of casein), HCP - diet with 21.2% CP in DM (8% of gluten, 10% of casein), and LSM - diet based on grain meals and meat-bone meal (21% CP in DM). After 28 days feeding, animals were euthanased by cervical dislocation and femur bones were collected, weighed and kept frozen until analyses. Diets with 21% protein (HCP, LSM) significantly increased weight of femur bones. Despite of the substantially higher ash level (7.1%) in the LSM diet than in the LCP diet (3.4%), rats of both groups had the similar bone concentration of Ca (15.7 +/- 1.1 vs. 17.4 +/- 1.1 g/kg) and Zn (178.7 +/- 7.9 vs. 173.0 +/- 8.5 mg/kg). However bone density in LSM rats was significantly higher than in LCP ones. Although rats fed HCP diet had intermediate bone density, the bone concentration of Ca (11.4 +/- 0.5 g/kg) and Zn (145.1 +/- 2.9 mg/kg) was significantly lower, than in animals fed LCP and LSM diets. This was related to the very wide protein/calcium (37:1 g/g) and protein/zinc (5.3:1 g/mg) ratios in HCP diet. Those ratios were narrowest in the LSM diet: 16.2:1 (CP/Ca) and 2.6:1 (CP/Zn). It can be conluded that protein/mineral ratio in a diet is a very important factor in bone development, besides dietary protein and ash contents itselves.     

Evaluation of five elements in lenses and aqueous humour of experimental rabbits after induced opacity

We evaluated the presence of Ca, Na, K, Cu and Zn in the lenses and aqueous humour of rabbits treated with an Nd:YAG laser to induce opacity of the crystalline. The mean concentrations of the elements found in control lenses were: Ca: 15.8+/-5.2 mg/kg; Na: 1.2+/-0.6 g/kg; K: 10.3+/-3.3 g/kg; Cu: 0.19+/-0.06 mg/kg; Zn: 20.6+/-3.0 mg/kg. With the exception of K and Zn, the values found in the lenses of treated eyes (Ca: 135+/-24 mg/kg; Na: 4.3+/-1.5 g/kg; K: 10.1 +/- 3.2 g/kg; Cu: 0.47+/-0.17 mg/kg; Zn: 21.8+/-4.2 mg/kg) were significantly higher than in the controls. On the other hand, the concentrations found in the aqueous humour of treated eyes (Ca: 21.7+/-4.5 mg/l; Na: 0.66+/-0.21 g/l; K: 0.29+/-0.10 g/l; Cu: 0.035+/-0.009 mg/l; Zn: 0.079+/-0.01 mg/l) were significantly lower than those of the controls. The greatest difference was observed for Na (-68.6%) and Cu (-52.7%), followed by Ca and Zn (-35.0% and -35.2%, respectively). A positive correlation was found between Ca and Na in treated lenses (r2 = 0.9226, p < 0.0001) whereas inverse correlations were found for both Ca (r2 = 0.9788, p<0.0001) and Na (r2 = 0.9491, p<0.0001) between the concentrations found in the lenses and in the aqueous humour of treated eyes.     

Interaction between pesticides and essential metal copper increases the accumulation of copper in the kidneys of rats

Male Sprague-Dawley rats, weighing 175-200 g, six per group were fed AIN 93M diet (CON) or diets containing 500 mg Ca (LCa), 7 mg Zn (LZn), 2 mg Cu (LCu), 60 mg Zn (HZn), or 12 mg Cu (HCu) per kilogram of diet in the following combinations: control (CON), LCa+LZn (LC+Z), LCa+LZn+LCu (LC+Z+C), or HZn+HCu (HZ+C) without or with a pesticides mixture (PM); Endosulfan, Thiram, and Acephate were added to the diets at 25% of LD50/kg. Rats were fed for 2 wk (small intestinal changes) or 4 wk (tissues changes). Plasma Zn was 47% lower than CON in the experimental groups. Plasma Cu and ceruloplasmin concomitantly decreased in the LC+Z+C group and increased with the addition of PM. Kidney Cu was 40% lower in LC+Z+C group, than CON and increased by 31% with PM; in the HZ+C+PM group, kidney Cu was 38% higher than the HZ+C group. Mucosal and small intestines Ca declined by 47% in all experimental groups; PM increased Zn in the LC+Z+C and HZ+C groups; PM further decreased intestinal and mucosal Cu retention in the LC+Z+C and HZ+C groups. Data suggest that low levels of PM in the diet can induce Cu accumulation in the kidney when dietary Zn and Cu are low or high.     

Effects of Astragalus membranaceus with Supplemental Calcium on Bone Mineral Density and Bone Metabolism in Calcium-Deficient Ovariectomized Rats

It has been reported that Astragalus membranaceus, an Asian traditional herb, has an estrogenic effect in vitro. To examine the possible role of A. membranaceus extract with supplemental calcium (Ca) on bone status in calcium-deficient (LCa) ovariectomized (OVX) rats, a total of 48 female rats were divided into six groups: (1) normal control, (2) sham operation with LCa (sham-LCa), (3) OVX with LCa (OVX-LCa), (4) A. membranaceus supplementation with OVX-LCa (OVX-MLCa), (5) Ca supplementation with OVX (OVX-Ca), and (6) A. membranaceus and Ca supplementation with OVX (OVX-MCa). A. membranaceus ethanol extract (500 mg/kg BW) and/or Ca (800 mg/kg BW) were administered orally for 8 weeks along with a Ca-deficient diet. Results revealed that Ca supplementation with or without A. membranaceus extract significantly improved bone mineral density, biomechanical strength, and ash weight of the femur and tibia in OVX rats. High Ca with A. membranaceus combination supplementation significantly increased the ash weight of the femur and tibia and decreased urinary Ca excretion compared with supplementation of Ca alone. Uterine weight was not changed by A. membranaceus administration in OVX rats. These results suggest that A. membranaceus extract combined with supplemental Ca may be more protective against the Ca loss of bone than A. membranaceus or supplementation of Ca alone in calcium-insufficient postmenopausal women.     

Influence of calcium on proliferation and phenotype alteration of cardiomyocyte in vitro

An accelerated weight gain is noted in the heart of Ca-deficient, hypertensive chick embryos maintained in a shell-less culture in vitro. We previously observed that the Ca handling property of cardiomyocytes isolated from the shell-less embryo is altered, i.e., faster Ca uptake, suggesting a requirement for adequate Ca supply and/or proper Ca handling in embryonic cardiac development. In this study, we have examined the function of Ca on cardiomyocytes by analyzing the effects of (1) various Ca concentration in the culture medium (NCa, 1.8 mmol/L; HCa, 2.8 mmol/L; LCa, 0.9 mmol/L), and (2) various modulators of Ca handling on cell proliferation and phenotype regulation in chick embryonic cardiomyocytes. The analytical parameters included cell number, DNA content, expression of cell cycle–specific and cardiomyocyte-specific proteins, and creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) enzyme activities. Cell number and total DNA were significantly larger (P < 0.01) in LCa cultures compared with those in NCa. The level of LDH was elevated (P < 0.01), but that of CPK was lowered in LCa. Expression of the G1-S–specific protein PCNA was raised, but that of the contractile proteins myosin and tropomyosin was substantially suppressed in LCa; in HCa, the cells did not proliferate as well, whereas the level of contractile proteins was higher. Thapsigargin, a sarcoplasmic reticulum (SR)-specific, Ca-ATPase inhibitor, simulated the effects of LCa by enhancing cell proliferation and lowering the expression of tropomyosin. These results suggest that culturing in low Ca concentration and inhibition of SR Ca pumping enhance myocardial cell proliferation and suppress sarcomeric protein expression, perhaps by inducing cellular de-differentiation. The in vitro effects of medium Ca concentration and Ca handling modulators on cardiomyocytes also suggest that the in vivo cardiomegaly of the SL embryos is a direct result of Ca-deficiency, and that Ca is important in the phenotype regulation of cardiomyocytes. J. Cell. Physiol. 177:289–298, 1998. © 1998 Wiley-Liss, Inc.     

The effect of restriction of dietary calcium on trabecular and cortical bone mineral density in the rats

This study aimed to investigate effects of restricted calcium intake on cortical and trabecular bone density in white rats. Low Ca diet was fed for six weeks, and bone density and bone metabolism parameters were assessed in blood. This study was carried out on 12 male white rats aged 12 weeks (Sprague-Dawley; SD). These rats were bred for 1 week and randomly assigned to the standard calcium diet group (SCa group, n = 6) and the low calcium diet group (LCa group; n = 6). The SCa group was given a modified AIN-93M mineral mix (with 0.5% Ca), which was made by adding calcium to a standard AIN93 diet, and the LCa Group was fed a modified AIN-93 Mineral mix (with 0.1% Ca). Femoral BMD and BMC were measured by DEXA in each rat. After trabecular bone was separated from cortical bone, volumetric bone mineral density (vBMD) was measured using pQCT. Serum Ca and P levels were measured as parameters of bone metabolism, and S-ALP, S-TrACP and-Dpd levels were also measured. The results revealed no significant differences in weight, growth rate, feed consumption and feed efficiency between the two groups before and after calcium-restricted diet (p > .05). No significant differences were also observed in bone length and bone mass between the two groups (p > .05). Although bilateral femoral BMDs were not significantly different between the two groups, bilateral femoral BMCs significantly decreased in the LCa group, compared with the SCa group (p = .023, p = .047). Bilateral cortical MDs were not significantly different between the two groups, either. However, trabecular BMD significantly decreased in the LCa group, compared with the SCa group (p = .041). U-Dpd and S-TrACP levels significantly declined in the LCa group, compared to the SCa group (p = .039, p = .010). There were no significant differences in serum Ca and P levels between the two groups (p > .05). However, a significant decrease in urinary Ca level (p = .001) and a significant increase in urinary P (p = .001) were observed in the LCa group, compared to the Sca group. These findings described that six-week low calcium diet led to decreased trabecular bone density, reduced urinary excretion of Ca and increased urinary excretion of P. As a result, Ca hemeostasis can be maintained.     

Zinc bone loss in chronic renal failure and chronic metabolic acidosis

The effects of chronic metabolic acidosis (CMA) on zinc (Zn) bone content and urinary excretion were examined in the presence of normal or reduced renal function together with some aspects of calcium (Ca) metabolism. Four groups of rats were compared. All were fed a 30% protein and 9 mg Zn/100 g diet. Two were uremic (U): The first developed acidosis (UA), which was suppressed in the other (UNA) by NaHCO₃ supplement. Two other groups had normal renal function: One was normal (CNA), and the other had NH₄Cl in the drinking water and acidosis (CA). Femur total Zn and Ca content was markedly reduced by CMA and was not affected by uremia. Zn urinary excretion was increased by CMA and unaltered by uremia. Ca urinary excretion was markedly reduced in uremic rats, but was enhanced in both acidotic conditions. Urinary Ca and Zn showed a strong correlation in uremic and in control rats. Plasma parathormone and 1,25(OH)₂D₃ were unchanged by CMA. These data are in agreement with a direct primary effect of CMA on bone in releasing buffers. CMA induces bone resorption and a parallel decrease of mineral bone components, such as Ca and Zn, with little or no role of PTH, 1,25(OH)₂D₃ and of uremia itself.     

Elevated white blood cell count, CRP and fibrinogen levels are not associated with increased anti-endothelial and anti-ox-LDL antibody, MCP-1, and RANTES levels in early onset occlusive carotid artery disease

BACKGROUND: Inflammatory processes have importance in atherosclerosis. We evaluated if subjects below 55 years of age with occlusive carotid artery disease have higher serum levels of antibodies against oxidized LDL and endothelial cells and the chemokines MCP-1 and RANTES than age matched subjects without atherosclerosis. METHODS AND RESULTS: Sixty patients with occlusive carotid artery disease (stenosis or occlusion) and 30 age-matched controls participated in the study. We measured the degree of carotid artery stenosis and intima-media thickness (IMT) by duplex ultrasound. White blood cell count (WBC), C-reactive protein (CRP), and fibrinogen levels were significantly higher in patients (means+/-SD: 7.5+/-1.8 vs. 6.1+/-1.1 G/L, p<0.001; 7.7+/-20.7 vs. 2.5+/-1.9 mg/L, p=0.015; and 3.7+/-0.9 vs. 3.1+/-0.5 g/L, p<0.001, respectively). Antibody levels against oxidized LDL and endothelial cells (21.1+/-22.9 and 19.9+/-15.3 EU/mL, p=0.6; and 19+/-15 vs. 20+/-9 U/mL, p=0.07) and RANTES and MCP-1 levels (72.4+/-32.3 vs. 73.8+/-27.3 ng/mL, p=0.7; and 468+/-1041 vs. 318+/-131 pg/mL, p=0.7) did not differ significantly between patients and controls and did not correlate with IMT. CONCLUSIONS: Higher levels of WBC, CRP, and fibrinogen suggest an ongoing inflammation in early-onset carotid atherosclerosis, but increased IMT is not associated by the elevation of serum levels of chemokines and antibodies evaluated in this study.     

Plasma tumor necrosis factor-alpha levels and insulin resistance in nondiabetic hypertensive subjects

OBJECTIVES: Tumor necrosis factor-alpha (TNF-alpha) is associated with insulin resistance in certain conditions. However, whether TNF-alpha is related to insulin resistance in hypertensive subjects is still controversial. The aim of this study was to determine the status of TNF-alpha and insulin resistance in hypertension. METHODS: Newly diagnosed nondiabetic 17 essentially hypertensive (6 men, 11 women) patients, and 11 control healthy subjects (5 men, 6 women) are involved in the study. Body mass index (BMI), insulin, fasting blood glucose, cholesterol, triglyceride, and TNF-alpha levels were measured. Insulin resistance is assessed according to homeostasis model of assessment (HOMA-IR). RESULTS: Serum insulin (8.4 +/- 2.7 vs. 6.1 +/- 1.4 mIU/ml; p < 0.01), triglyceride (245.0 +/- 39.9 vs. 193.0 +/- 22.8 mg/dl; p < 0.01), and TNF-alpha (4.2 +/- 0.7 vs. 3.0 +/- 0.6 pg/ml; p < 0.001) levels, and HOMA-IR (2.0 +/- 0.8 vs. 1.3 +/- 0.3; p < 0.001) were significantly higher in the hypertensive patients compared to the normotensive control group. There were positive correlations between TNF-alpha levels and body mass index (r = 0.64, p < 0.01), and triglyceride (r = 0.55 p = 0.02) levels in the whole study group. However, there was no correlation of either TNF-alpha or HOMA-IR. CONCLUSIONS: Our data revealed that hypertensive patients have insulin resistance and higher TNF-alpha levels, but there is no relation between TNF-alpha levels and insulin resistance.     

Calcium exacerbates the inhibitory effects of phytic acid on zinc bioavailability in rats

BackgroundComplementary feeding of breastfed infants with foods high in bioavailable zinc (Zn) can help meet physiological requirements for Zn. Some infant cereals contain high concentrations of phytic acid (PA) and calcium (Ca) that may reduce absorbable Zn.ObjectivesThis study measured PA, Zn and Ca concentrations in selected infant cereals sold in Canada and investigated the effects of dietary PA and Ca at concentrations present in infant cereals on Zn bioavailability in rats.Methods and resultsMale Sprague-Dawley rats (36-day old) were fed a control diet containing normal Zn (29.1 mg/kg) and Ca (4.95 g/kg) or six test diets (n = 12/diet group). Test diets were low in Zn (8.91–9.74 mg/kg) and contained low (2.16–2.17 g/kg), normal (5.00–5.11 g/kg) or high (14.6–14.9 g/kg) Ca without or with added PA (8 g/kg). After 2 weeks, rats were killed and Zn status of the rats was assessed. PA, Zn and Ca concentrations in infant cereals (n = 20) differed widely. PA concentrations ranged from undetectable to 16.0 g/kg. Zn and Ca concentrations ranged from 7.0–29.1 mg/kg and 0.8–13.4 g/kg, respectively. The [PA]/[Zn] and [PA × Ca]/[Zn] molar ratios in infants cereals with detectable PA (16 of 20 cereals) ranged from 22–75 and 0.9–14.9 mol/kg, respectively, predicting low Zn bioavailability. Body weight, body composition (lean and fat mass), right femur weight and length measurements and Zn concentrations in serum and femur indicated that diets higher in Ca had a more pronounced negative effect on Zn status of rats fed a PA-supplemented diet. Addition of PA to the diet had a greater negative effect on Zn status when Ca concentration in the diet was higher.ConclusionThese results show that, in rats, higher concentrations of dietary Ca and PA interact to potentiate a decrease in bioavailable Zn and may suggest lower Zn bioavailability in infant cereals with higher PA and Ca concentrations.     

Effects of vitamin E on microsomal Ca(2+) -ATPase activity and calcium levels in streptozotocin-induced diabetic rat kidney

Vitamin E treatment has been found to be beneficial in preventing or reducing diabetic nephropathy. Increased tissue calcium and abnormal microsomal Ca(2+)-ATPase activity have been suggested as contributing factors in the development of diabetic nephropathy. This study was undertaken to test the hypothesis that vitamin E reduces lipid peroxidation and can prevent the abnormalities in microsomal Ca(2+)-ATPase activity and calcium levels in kidney of streptozotocin (STZ)-induced diabetic rats. Male rats were rendered diabetic by a single STZ injection (55 mg x kg(-1) i.p.). After diabetes was verified, diabetic and age-matched control rats were untreated or treated with vitamin E (400-500 IU kg(-1) x day(-1), orally) for 10 weeks. Ca(2+)-ATPase activity and lipid peroxidation (MDA) were determined spectrophotometrically. Blood glucose levels increased approximately five-fold (> 500 mg x dl(-1)) in untreated-diabetic rats but decreased to 340+/-27 mg x dl(-1) in the vitamin E treated-diabetic group. Kidney MDA levels did not significantly change in the diabetic state. However, vitamin E treatment markedly inhibited MDA levels in both control and diabetic animals. Ca(2+)-ATPase activity was 0.483+/-0.008 U l(-1) in the control group and significantly increased to 0.754+/-0.010 U l(-1) in the STZ-diabetic group (p < 0.001). Vitamin E treatment completely prevented the diabetes-induced increase in Ca(2+)-ATPase activity (0.307+/-0.025 U l(-1), p < 0.001) and also reduced the enzyme activity in normal control rats. STZ-diabetes resulted in approximately two-fold increase in total calcium content of kidney. Vitamin E treatment led to a significant reduction in kidney calcium levels of both control and diabetic animals (p < 0.001). Thus, vitamin E treatment can lower blood glucose and lipid peroxidation, which in turn prevents the abnormalities in kidney calcium metabolism of diabetic rats. This study describes a potential biochemical mechanism by which vitamin E supplementation may delay or inhibit the development of cellular damage and nephropathy in diabetes.     

Diabetes-induced decrease in rat brain microsomal Ca2+-ATPase activity

The Ca(2+)-ATPase activity of rat brain microsomes was studied in streptozotocin (STZ)-induced diabetes. Male rats, 200-250 g, were rendered diabetic by injection of STZ (45 mg kg(-1) body weight) via the teil vein. Brain tissues were collected at 1, 4 and 10 weeks after diabetes was induced for determination of Ca(2+)-ATPase activity, lipid peroxidation and tissue calcium levels. Diabetic rats had significantly elevated blood glucose levels compared to controls. Blood glucose levels were 92.92 +/- 1.22 mg dl(-1) (mean +/- SEM) for the control group, 362.50 +/- 9.61 mg dl(-1) at 1 week and >500 mg dl(-1) at 4, 8 and 10 weeks for the diabetics. Enzyme activities were significantly decreased at 1, 4, 8 and 10 weeks of diabetes relative to the control group (p < 0.001). Ca(2+)-ATPase activity was 0.084 +/- 0.008 U l(-1), 0.029 +/- 0.005 U l(-1), 0.029 +/- 0.006 U l(-1), 0.033 +/- 0.003 U l(-1) and 0.058 +/- 0.006 U l(-1) (mean +/- SEM) at control, 1, 4, 8 and 10 week of diabetes respectively. The change in calcium levels in diabetic rat brain at 8 and 10 weeks of diabetes was significantly higher than that of the control group (p < 0.05). On the other hand lipid peroxidation measured as TBARS (thiobarbituric acid reactive substances) was significantly higher at 8 and 10 weeks of diabetes (p < 0.05). The increase in lipid peroxidation observed in diabetic rat brain may be partly responsible for the decrease in calcium ATPase activity.     

Dietary zinc effects on zinc, calcium, and magnesium content in bones of growing rats

The aim of the present study was to assess dietary zinc effects on femur weight and mineral content in growing rats. For this purpose, 70 weanling Sprague-Dawley rats were divided into four groups. Each group was subject to a diet containing 2 (BZ), 5 (DZ), 10 (MZ), and 30 (CZ) ppm zinc. The calcium and magnesium content in all diets was 5 g/kg and 507 mg/kg, respectively. The animals were kept on this regime for 28 d and then sacrificed and their femurs were removed for analysis using atomic absorption spectrophotometry. The weights of the BZ and DZ groups were significantly different from the MZ and CZ groups (38.5±10.5, 89.9±13.7, 118.6±13.6 and 134±19.9 g, p<0.01) respectively. There were no differences between the MZ and CZ groups. Femur weight also varied with dietary zinc, as it was significantly different among all groups (BZ, 265±49 mg; DZ, 380±40 mg; MZ, 452±54 mg; CZ, 735±66 mg; p<0.01). The femur zinc content varied with diets, following a different pattern than the above parameters. Femur zinc from the BZ group (51.5±5.4 ppm) was significantly different from the MZ and CZ groups (115.9±14.2 and 175.0±13.5 ppm, respectively), whereas the DZ group (62.5±11.3 ppm) did not differ from the other three groups. The femur content of calcium (BZ, 83.2±9.8 mg/g; DZ, 88.0±9.2 mg/g; MZ, 90.2±13.6 mg/g; CZ, 83.1±14.7 mg/g) and magnesium (BZ, 1.82±0.13 mg/g; DZ, 1.98±0.09 mg/g; MZ, 1.93±14 mg/g; CZ, 1.83±0.19 mg/g) were not significantly different among the groups, nor was the calcium-magnesium ratio. These results suggest that although dietary zinc deficiency retards growth and causes bone fragility, bone deposition of calcium and magnesium and its ratio are not affected.     

Removal of the uropygial gland does not affect serum lipids, cholesterol and calcium levels in the rock pigeon Columba livia

The uropygial gland is an organ typical of birds, over which no agreement regarding its function has been attained yet. Authors attribute to the gland an hydrophobic action. The function of the gland is herein explored in rock pigeon, Columba livia, was used as experimental model for trials. The study was focused on the physiological role of the gland in relation to biochemical parameters. Pigeons were separated in groups of six birds each: a) intact control, b) surgical control, c) ablationed. Comparing control specimens with gland-removed specimens, recorded serum levels after 32 days were the following (mean+/-SD): cholesterol (g/l), 3.7+/-0.6 vs. 4.1+/-0.6; total lipids (g/l), 15.7+/-2.0 vs. 13.7+/-2.7; calcium (mg/l), 100.5 +/- 24.3 vs. 99.1 +/- 9.2. None of the differences were statistically significant. Thus, no alterations of basic biochemical parameters associated with metabolism of lipids were registered. In one group of birds the calcium and cholesterol levels were determined 122 days after surgery; in this case values remained unchanged related to the beginning of the trials. Results suggest that the uropygial gland is not physiologically related to either the homeostasis of total lipids, cholesterol or the regulation of calcium metabolism.     

Dietary phytate × calcium/zinc millimolar ratios and zinc nutriture in some Ontario preschool children

Millimolar ratios of phytate/Zn, Ca x phytate/Zn, and Ca x phytate/Zn per 4.2 MJ were calculated from 3-d weighed-food records collected from 62 male (M) (mean age: 58 +/- 7 mo [mean +/- SD]) and 44 female (F) (mean age: 58 +/- 6 mo) preschool children from Southern Ontario. Food-composition values for phytate were based on laboratory analysis and the literature. No gender differences existed for median millimolar ratios of phytate/Zn (median: M, 5.3; F, 5.3), and Ca x phytate/Zn per 4.2 MJ (M, 68.1; F, 59.5), but median intakes of phytate (M, 399; F, 333 mg/d) and median millimolar ratios of Ca x phytate/Zn (median: M, 102.1; F, 72.3; p less than 0.01) were higher for boys than for girls. Of the children, only two (1M, 1F) and 22 (17 M, 5F) had millimolar ratios of phytate/Zn and Ca x phytate/Zn per 4.2 MJ, respectively, that were above critical values. Millimolar ratios of Ca x phytate/Zn (p = 0.06) and Ca x phytate/Zn per 4.2 MJ (p = 0.05) were higher in boys with hair zinc less than 1.07 mumol/g v greater than or equal to 1.07 mumol/g. Analysis of variance showed that height was influenced by an interaction between millimolar ratios of Ca x phytate/Zn per 4.2 MJ and sex (p = 0.0007), when age and midparent height were treated as covariates. Results suggest that dietary Ca x phytate/Zn millimolar ratios, when expressed per 4.2 MJ, influenced the zinc nutriture of these Southern Ontario boys.     

Effect of sucrose diet on insulin secretion in vivo and in vitro and on triglyceride storage and mobilisation of the heart of rats

Basal heart triacylglycerol (TG) (mumole triacylglycerol/g of dry weight) (- before "in vitro" Langendorff perfusion -) was significantly higher in animals rendered chronically hypertriglyceridaemic (H) by a 63% sucrose-rich diet than in controls (C, standard diet); 28 +/- 2.6 means + SEM vs. 19.3 +/- 1.2; respectively (p less than 0.01). After 40' perfusion with Krebs-Henseleit buffer + 5.5 mM glucose, 2.5 mM Ca++, TG content fell to 14.2 +/- 0.6 in C and 14.9 +/- 1.9 in H (n.S.). Administration of 1 n mol x min-1 of glucagon (Gn) from min 20 to 40 reduced TG to 9.0 +/- 0.5 in C (p less than 0.05). In contrast no effect of Gn was observed in H (TG at min 40: 16.7 +/- 2.5). Glycogen (Gly) content (mumol/g of dry weight) after Gn perfusion fell from 30 +/- 1.9 to 17 +/- 2.1 (p less than 0.01) in C, while again no effect was recorded in H. "In vivo" plasma glucose fractional coefficient disappearance rate was lower (p less than 0.001) in H: 1.01 x 10(-2) +/- 0.09 x 10(-2) vs 2.61 x 10(-2) +/- 0.14 x 10(-2) in C, in spite of H showing hyperinsulin secretion. Hyperinsulinism was further documented by "in vitro" Iri release studies from incubated pancreas pieces. In the absence of glucose (G) from the incubation medium H produced 541 +/- 19.8 mU/mg weight Tissue/20', while C produced 91.2 +/- 12.7 (p less than 0.001). With 100 mg% G, H released 1058 +/- 259 and C 377 +/- 82.5 (p less than 0.001). It is suggested that hyperinsulin secretion plus insulin resistance may account for the above findings.     

Effects of a calcium/vitamin D/Zinc combination on anti-osteoporosis in ovariectomized rats

BackgroundOsteoporosis is a major health problem in postmenopausal women, and characterized by deteriorated bone mass and micro-architecture. There have been some clinical trials demonstrating the beneficial effects of vitamin-D and some trace elements on calcium absorption and attenuation of osteoporosis development. However, effects of the combination of vitamin-D and zinc on calcium absorption and osteoporosis have not been adequately investigated.MethodsNetwork pharmacology was first performed to explore possible correlations between calcium/vitamin D/zinc and osteoporosis. Forty-nine female Sprague-Dawley rats (6 months old, 250 ± 20 g) were randomized into 7 experimental groups with 7 animals per group for the in vivo study, including one sham surgery control group, one ovariectomizing (OVX) group, and 5 OVX plus treatment groups. At the end of animal experiment, animal tibia and femur leg bones and blood were collected for H&E staining, bone microstructure analysis by a micro-CT, measurement of bone and serum Ca, P and Zn concentrations, and immunohistochemical detection of macrophage-colony stimulating factor receptor (M-CSFR) and receptor activator of nuclear factor-kappa B ligand (RANKL).ResultsThe network pharmacology analysis identified 57 candidate targets that were related to the osteoporosis-Ca/VitD/Zn interconnections. Further pathway analysis suggested that the combined treatment of Ca, VitD and Zn attenuated osteoporosis via modulation of metabolic pathways. We found that a therapy with Ca/VitD-M/Zn-M (73 mg/kg/day Ca, 0.6 g/kg/day VitD3 and 0.6 mg/kg/day zinc citrate) could significantly suppress the progression of osteoporosis in rats. After the Ca/VitD-M/Zn-M treatment, the ratio of bone volume/tissue volume, trabecular number and the trabecular thickness were all significantly elevated while the extent of trabecular separation was significantly reduced. Additionally, both serum calcium and bone calcium levels were significantly upregulated by the Ca/VitD/Zn treatment in a dose-dependent manner. The combination of Ca/VitD-M/Zn-M was superiou to either Ca/VitD-L/Zn-L or Ca/VitD-H/Zn-H treatment for such an effect. Moreover, the osteoporosis-associated M-CSFR and RANKL factors were both significantly downregulated by the Ca/VitD-M/Zn-M treatment in bone tissues of OVX rats.ConclusionsThe combined supplement of VitD and Zn facilitates the Ca(2 +) absorption and attenuates the development of osteoporosis via down-regulation of osteoporosis-associated factors M-CSFR and RANKL, thus potentially constitutes an alternative therapy for the postmenopausal osteoporosis.     

Differential effects of hGH and IGF-I on body proportions

The differential growth effects of hGH and IGF-I on the upper/lower (U/L) body segment in relation to height (Ht) were analyzed in 15 patients with isolated Growth hormone deficiency (IGHD,:7M, 8F) mean age 5.0 +/- 3.2 (SD) years treated with hGH; 21 patients with multiple pituitary hormone deficiency including growth hormone (MPHD: 14M, 7F) aged 10.0 +/- 3.8, treated with hGH; 9 patients with Laron Syndrome (LS) (4M,5F) aged 6.9 +/- 5.6 years treated with IGF-I; 9 boys with intrauterine growth retardation (IUGR) aged 6.3 +/- 1.25 years treated by hGH; and 22 boys with idiopathic short stature (ISS) aged 8.0 +/- 1.55 years treated by hGH. The dose of hGH was 33 microg/kg/day, that of IGF-I 180-200 microg/kg/day. RESULTS: the U/L body segment ratio in IGHD patients decreased from 2.3 +/- 0.7 to 1.1 +/- 0.7 (p <0.001), and the Ht SDS increased from -4.9 +/- 1.3 to 2.3 +/- 1 (p < 0.001) following treatment. In MPHD patients the U/L body segment decreased from 1.1 +/- 1.1 to -0.6 +/- 1.0 (p < 0.001), and the Ht SDS increased from -3.3 +/- 1.4 to -2.5 +/- 1.0 (p < 0.009). In the LS group the U/L body segment ratio did not change with IGF-I treatment but Ht improved from -6.1 +/- 1.3 to -4.6 +/- 1.2 (p < 0.001), The differential growth response of the children with IUGR and with ISS resembled that of the children with LS. CONCLUSIONS: hGH and IGF-I act differentially on the spine and limbs.     

Intestinal permeability to lactulose and mannitol in growing rats with iron-deficiency anemia

Iron deficiency can have nonhematological manifestations, some of which may affect the gastrointestinal tract. The aim of this study was to determine if iron-deficiency anemia in growing rats affected small-bowel permeability as assessed by the urinary ratio of lactulose and mannitol. Thirty-seven male Harlan Sprague-Dawley rats (21 d of age) were randomly divided into two groups and fed either an iron-deficient (n=19) or an iron-sufficient diet (n=18) that contained either 13.5 or 43.8 mg of iron/kg diet, respectively. Animals were evaluated between 25 and 38 d of dietary treatment. Intestinal permeability was assessed by measuring the lactulose/mannitol urinary ratio following administration of a solution that contained the two sugars. At the end of the study, the mean body weight of rats fed the low-iron diet was approx 95% that of the controls. The mean hemoglobin (g/dL) was significantly lower in the low-iron diet group (11.2±1.4) than in the control group (16.9±0.8) (p=0.001). The liver iron concentration (μg/g) of the anemic group (41.4±4.7) was also statistically (p=0.001) lower than in the control group (116.6±18.2). The lactulose/mannitol ratio was lower in the anemic rats (2.0±0.7) than in the control group (2.6±0.7) (p=0.008), a finding that is not suggestive of intestinal mucosal atrophy, previously described in anemic children.