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BACKGROUND Nutritional rickets is believed to result from the interaction of inadequate serum 25-hydroxyvitamin D [25(OH)D] concentration and dietary calcium intake, but this interaction has not been confirmed in children with rickets. Determining the vitamin D requirements to prevent nutritional rickets has been thwarted by inconsistent case definition, inadequate adjustment for calcium intake and other confounders, and 25(OH)D assay variability. OBJECTIVES To model the 25(OH)D concentration associated with nutritional rickets in calcium-deprived Nigerian children, adjusted for confounding factors, and develop a general approach to define vitamin D status while accounting for calcium intake. METHODS Logistic regression was used to model the association of serum 25(OH)D with having rickets adjusted for calcium intake in a reanalysis of a case-control study in Nigerian children. The matching variables age, sex, weight-for-age z score, and 4 additional significant variables were selected [religion, age began walking, phosphorus intake, and the 25(OH)D × calcium intake interaction] using a rigorous 7-step algorithm. RESULTS Cases had significantly (P

Two experiments were carried out in order to evaluate the efficacy of a partially decreased dietary cation-anion difference (pDCAD) of dry period rations of dairy cattle ((DCAD ~ 0 mEq/Kg DM) in prevention of postpartum subclinical hypocalcemia (SCH). The primary goal of the Experiment I was to compare the efficacy of a pDCAD strategy in minimizing SCH against a full DCAD (fDCAD ~ − 50 mEq/Kg DM) and a low calcium diet (LCD) in late (21 days (d)) pregnancy in Farm 1, using 66 multiparous cows (parity ≥ 3). The primary goal of Experiment II was to evaluate the effect of extension of a pDCAD to whole dry period (expDCAD-60 days), enrolling 40 cows (parity ≥ 3) to compare a pDCAD vs. expDCAD strategy. In both experiments, a primiparous heifers group was included as well. Serum Ca, Pi, Mg, and energy status indicators β-hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA) were monitored pre- and post-partum, serially. Experiment I showed a significantly lower Ca, a numerically higher prevalence of SCH, and significantly lower NEFA and BHB in pDCAD vs. fDCAD. The prevalence of subclinical ketosis (SCK) was significantly higher in fDCAD peripartally. In Experiment II, a significantly higher Ca and lower prevalence of SCH were observed in expDCAD vs. pDCAD postpartum, while BHB, NEFA, and the prevalence of SCK were not significantly different. The prevalence of SCH in primiparous heifers in both experiments was about 30%. Overall, compared to common ordinary fDCAD strategy, pDCAD could be potentially regarded as a practical intervention, when the adverse effects of fDCAD are unavoidable.

Objective This systematic review aimed to address whether the alveolar socket repair after a tooth extraction is impacted by an osteoporotic phenotype and propose methodological observations. Design A search strategy in MEDLINE/PubMed, EMBASE, Web of Science, and Scopus databases was performed. Quality assessment was carried out through the SYRCLE Risk of Bias tool. Results Out of the 1147 potentially relevant records, 25 met the inclusion criteria. Most of the studies were performed in rats, and ovariectomy (OVX) was the most frequent osteoporosis induction method. Histomorphometry, micro-computed tomography (microCT), and immunohistochemistry were the main bone repair evaluation methods. Most of the included studies (88 %) presented negative impacts of osteoporosis on the alveolar socket repair. Only three studies (12 %) showed no statistical differences among groups. Overall, most of the quality assessment categories presented a high percentage of unclear risk of bias due to insufficient information in the studies. Conclusions The results indicated that an osteoporotic phenotype seems to impair alveolar socket repair after tooth extraction. However, there is still a lack of information and standardization. Therefore, further studies should consider the proposed methodological aspects regarding animal characteristics, OVX associated with a low calcium diet, waiting 8 weeks to osteoporosis induction, maxillary molars as the best option for tooth extraction, confirming and reporting OVX and osteoporosis success, and an appropriate method of repair analysis.

Caseinomacropeptide (CMP) is the 64 C-terminal amino acid residue of κ-casein, formed by chymosin cleavage during cheese manufacture. This study examined the effects of oral administration of a CMP-enriched extract (CMPEE), obtained from a local dairy plant, on the Ca content of mouse femurs. Animals received low (0.1%, w/v), normal (0.5%, w/v) or high (1.2%, w/v) Ca diet for 3 or 8 weeks and CMPEE diluted (1:10) in their drinking water. No significant differences in Ca content were observed in faeces, kidney, urine or blood serum compared with control animals. The oral administration of CMP to mice significantly enhanced the Ca content in femur under a low-Ca diet model, especially during the period of full body development (3 weeks), in which case a significant 12% Ca increase was observed. These findings pave the way for further studies aimed at supplementing infant food with industrially-obtained CMP-enriched extract for enhanced bone health.

Background Kidney stone disease is common in industrialized countries. Recently, it has attracted growing attention, because of its significant association with adverse renal outcomes, including end stage renal disease. Calcium-containing kidney stones are frequent with high recurrence rates. While hypercalciuria is a well-known risk factor, restricted intake of animal protein and sodium, combined with normal dietary calcium, has been shown to be more effective in stone prevention compared with a low-calcium diet. Notably, the average sodium intake in Switzerland is twice as high as the WHO recommendation, while the intake of milk and dairy products is low. Methods We retrospectively analyzed Swiss recurrent kidney stone formers (rKSF) to test the impact of a low-sodium in combination with a low-calcium diet on the urinary risk profile. In patients with recurrent calcium oxalate containing stones, we investigated both, the consequence of a low-sodium diet on urinary volume and calcium excretion, and the influence of a low-sodium low-calcium diet on urinary oxalate excretion. Results Of the 169 patients with CaOx stones, 49 presented with hypercalciuria at baseline. The diet resulted in a highly significant reduction in 24-h urinary sodium and calcium excretion: from 201 ± 89 at baseline to 128 ± 88 mmol/d for sodium (p

Clinical evidence suggests that, compared with alendronate, risedronate reduces fracture risk faster and more potently, with less bone mass gain. We tested the hypothesis that risedronate improves bone quality faster than alendronate using calcium-deficient, ovariectomized (OVX) rats. Female Sprague–Dawley rats at 24 weeks of age were divided into sham-operated and OVX groups and fed a low-calcium (0.05 %) diet under paired feeding. After 12 weeks, OVX rats were divided into five groups and treated with vehicle, risedronate (3.5 and 17.5 μg/kg/week, s.c.) or alendronate (7 and 35 μg/kg/week, s.c.). Rats were killed 6–8 weeks later and the bone architecture and strength of the left femur were evaluated by micro-computed tomography and a three-point bending test. Trabecular bone mineral density (BMD), number and thickness were significantly lower in OVX rats than in the sham-operated group. Cortical BMD, bone area (Ct.Ar), and thickness (Ct.Th) were similarly decreased. Risedronate significantly improved Ct.Ar (+8 %) and Ct.Th (+9 %) at 6 weeks, while alendronate only caused a significant improvement in Ct.Ar (+8 % at 6 weeks) and only at the higher dose. At 8 weeks, both risedronate and alendronate significantly increased trabecular BMD compared with the vehicle. Bone strength parameters showed a significant correlation between Ct.Ar and Ct.Th. Risedronate significantly improved maximum load at 6 weeks, while alendronate failed to produce any significant changes. Our results suggest that risedronate is superior to alendronate at improving cortical bone architecture and strength, and that enhanced bone quality partly accounts for risedronate’s efficacy.

The inbred genetic hypercalciuric stone-forming (GHS) rats exhibit many features of human idiopathic hypercalciuria and have elevated levels of vitamin D receptors (VDR) in calcium (Ca)-transporting organs. On a normal-Ca diet, 1,25(OH)2D3 (1,25D) increases urine (U) Ca to a greater extent in GHS than in controls [Sprague-Dawley (SD)]. The additional UCa may result from an increase in intestinal Ca absorption and/or bone resorption. To determine the source, we asked whether 1,25D would increase UCa in GHS fed a low-Ca (0.02%) diet (LCD). With 1,25D, UCa in SD increased from 1.2 ± 0.1 to 9.3 ± 0.9 mg/day and increased more in GHS from 4.7 ± 0.3 to 21.5 ± 0.9 mg/day ( P < 0.001). In GHS rats on LCD with or without 1,25D, UCa far exceeded daily Ca intake (2.6 mg/day). While the greater excess in UCa in GHS rats must be derived from bone mineral, there may also be a 1,25D-mediated decrease in renal tubular Ca reabsorption. RNA expression of the components of renal Ca transport indicated that 1,25D administration results in a suppression of klotho, an activator of the renal Ca reabsorption channel TRPV5, in both SD and GHS rats. This fall in klotho would decrease tubular reabsorption of the 1,25D-induced bone Ca release. Thus, the greater increase in UCa with 1,25D in GHS fed LCD strongly suggests that the additional UCa results from an increase in bone resorption, likely due to the increased number of VDR in the GHS rat bone cells, with a possible component of decreased renal tubular calcium reabsorption.

RESUMEN El objetivo del estudio es determinar la asociacion entre los factores de riesgo: indice de masa corporal bajo, alimentacion con bajo contenido de calcio, menarquia tardia, menopausia precoz, sedentarismo y condicion socioeconomica de pobreza en pacientes con osteoporosis posmenopausica (OP) de los Hospitales Vicente Corral y Jose Carrasco. Estudio de casos y controles, participaron 112 mujeres posmenopausicas con osteoporosis con densitometria osea T-score

Fracture risk among patients with urolithiasis is underestimated. Indeed, vertebral fracture prevalence was reported to be increased fourfold compared to general population. Dual-energy X-ray absorptiometry scan is a reliable test to evaluate bone mineral density. To date, this test is not refunded by health public insurance for stone-forming patients with idiopathic hypercalciuria. We suggest that bone mineral density should be evaluated in this population especially when additional potential bone loss risk factors are present such as pathological fractures, menopause, heavy smoking, long term steroid treatment or endocrinopathy. Thus, it is mandatory to stress the point that a low calcium diet should be avoided in this population with a potential low bone mineral density.

High fluoride levels in drinking water sources are a problem throughout the East African Rift Valley and can lead to dental fluorosis (DF) and skeletal fluorosis (SF) in exposed local populations. Two villages in the Hai District of northern Tanzania in which fluoride has been identified as a problem were investigated in a pilot study. Fluoride levels in drinking water sources were measured and the prevalence of DF and deformities due to SF were assessed in children attending school in the two villages. The assessment also recorded the source of drinking water as well as children's height, weight and 3-day food diaries. Over one-quarter of the children in both villages had skeletal deformities, despite one village having much higher levels of fluoride in its drinking water sources. More than 90% of children in both villages had DF. SF and DF are major problems in this area. Deformities relating to SF are common, but the reasons for individual susceptibility remain unclear and may include a low calcium diet, ingestion of magadi (local salt) with high fluoride, or genetic factors.

It is clinically important to check whether sufficient supporting bone mass is maintained in subjects with a low calcium diet. In this study, alveolar and femoral bone mass were measured after tooth movement in calcium-sufficient and -deficient rats, and the correlation between mechanical stress and bone mass was examined using the serum level and histological observation. Seventy rats were divided into 2 groups : normal (NDG) and low calcium diet (LCG) groups. After feeding for 28 days, the distance of tooth movement and the alveolar and femoral bone mass were observed on days 1, 3, 5 and 7 after fitting the appliance. Tooth movement distance was large in LCG. Alveolar bone mass in NDG and LCG showed a different tendency than tooth movement ; the former was increased and the latter was decreased. Body weight decreased from the start of the experiment until day 3 in both groups, and increased gradually thereafter. Femoral bone mass in NDG slightly decreased and then recovered at day 7, but such a result was not observed in LCG. These results suggest that the tooth was able to move when an orthodontic force was applied in rats, even in cases of low alveolar bone mass, although various physical influences were present.

Objective: The purpose of this study was to examine the effects of vitamin K2 administration on calcium balance and bone mass in young rats fed a normal or low calcium di

The effects of grape seed proanthocyanidins extract (GSPE, 3mg in 100g of high-calcium diet with a calcium content of 1697mg/100g) on rat metaphysis tibia formation following feeding of a low-calcium diet (30% of calcium in the standard diet) were investigated by examining bone density, mineral content, geometric and bone strength. Five-week old male Wistar rats (n=40) were randomly divided into a control (Co) group, a low-calcium diet (LC) group, a low-calcium diet • high-calcium diet (LCH) group, and a lowcalcium diet • high-calcium diet with supplementary GSPE (LCHG) group. The metaphysis tibia bones were analyzed using three-dimensional peripheral quantitative computed tomography (pQCT), while whole tibia bones were tested for mechanical resistance using a material testing machine. We found no significant differences in body weight among the 4 groups. All bone parameters in the LC group were significantly lower than these in the Co group ( P P P P P P

We examined the effect of vitamin D supplementation on bone growth in young rats fed a normal or low calcium diet.Fifty female Sprague-Dawley rats, 6 weeks of age, were randomized by stratified weight method into five groups with 10 rats in each group: baseline control, 0.5% (normal) or 0.1% (low) calcium diet, and 0.5 or 0.1% calcium diet + vitamin D (25 microg/100 g, food intake). Duration of the experiment was 10 weeks.Vitamin D supplementation stimulated intestinal calcium absorption and increased urinary calcium excretion in rats fed a low or normal calcium diet. Vitamin D supplementation prevented the reduction in periosteal bone gain but enhanced enlargement of the marrow cavity and reduced the maturation-related cancellous bone gain in rats fed a low calcium diet, and increased the maturation-related cancellous and cortical bone gains in rats fed a normal calcium diet.This study shows the differential effects of vitamin D supplementation on born growth in young rats fed a normal or low calcium diet.

Animal models are widely used to explore the pathogenesis and management of osteoporosis. Mice are increasingly being used in animal models. We have evaluated the precision, accuracy, and ability to monitor changes in bone mineral measurements of mice with the Piximus and Hologic QDR 2000 devices. One hundred and twenty-two C57/BL6 mice were used in this study; 70 of them were put on a low calcium diet and followed prospectively for 14 wk. They were measured using both devices at baseline and at wk 14. Using the Piximus, we measured the whole body, the tibia, and two caudal vertebrae. Using the Hologic, we measured the tibia, which we divided into three equal parts. The remaining mice were used to evaluate the precision and accuracy of the measurement. The accuracy, which was determined only for the Hologic device, revealed a mean difference between the in vivo bone mineral content (BMC) and the ash weight of 0.1 mg. The precision, evaluated from the coefficient of variation (%) and the Smallest Detectable Difference (SDD, in absolute values) was good for both devices, confirming their ability to detect small differences in longitudinal studies: as little as 0.004 g for the BMC of the total tibia on both devices, and 0.003 g/cm 2 for whole body bone mineral density (BMD) on the Piximus. The BMC found using the two devices was comparable, whereas the BMD obtained on the Hologic device was nearly double that found using the Piximus. The comparison of the results by Bland and Altman's method showed that the difference between the results was not dependent on the magnitude of the measurement. We concluded that bone density and bone-density changes in mice can be measured precisely in vivo using the Hologic and Piximus devices; the latter being able to measure the whole body BMD with good precision.

In this study, the experimental denture base on the hard palate of the molar region of osteoporotic rats was designed to cover without any mechanical pressure or to load continuous pressure (0.5, 1.5 or 3.4 kPa). Experimental osteoporosis was induced by ovariectomy and feeding on a low calcium diet. Histopathological changes induced by non-pressure covering or continuous pressure in the tissues under the experimental denture bases were examined. Regarding the histological changes induced by continuous pressure, this was evaluated in relation to the time course of the intensity of the continuous pressure. In the tissues under the denture base in osteoporotic condition with non-pressure covering, no histopathological changes caused by non-pressure covering were observed except for a transient slight proliferative reaction in the epithelial ridge. The following histopathological changes were observed in the tissues under the denture base in the osteoporotic condition bearing continuous pressure; (i) bone resorption was induced on the periosteal surface (Ps) in the osteoporotic-3.4 kPa group, and on the pressure side of the endocortical surface (p-Ec) in the osteoporotic-1.5 and -3.4 kPa group, (ii) the appearance of osteoclasts on the p-Ec in the osteoporotic-3.4 kPa group was earlier than that on the Ps in a same group, (iii) bone resorption on the pressure side of the Ec in the osteoporotic-3.4 kPa group manifested at the earlier stage than that in the osteoporotic-1.5 kPa group, (iv) bone formation following bone resorption on the p-Ec was observed more markedly than that on the Ps and (v) histopathological changes in the tissues under the denture base in experimental osteoporosis bearing continuous pressure had an intimate relationship with the initial intensity and the time course of continuous pressure.

Genetic hypercalciuric stone-forming (GHS) rats demonstrate increased intestinal Ca absorption, increased bone resorption, and reduced renal tubular Ca reabsorption leading to hypercalciuria and all form kidney stones. GHS have increased vitamin D receptors (VDR) at these sites of Ca transport. Injection of 1,25(OH)2D3 (1,25D) leads to a greater increase in urine (u)Ca in GHS than in control Sprague-Dawley (SD), possibly due to the additional VDR. In GHS the increased uCa persists on a low-Ca diet (LCD) suggesting enhanced bone resorption. We tested the hypothesis that LCD, coupled to inhibition of bone resorption by alendronate (alen), would eliminate the enhanced 1,25D-induced hypercalciuria in GHS. SD and GHS were fed LCD and half were injected daily with 1,25D. After 8 days all were also given alen until euthanasia at day 16. At 8 days, 1,25D increased uCa in SD and to a greater extent in GHS. At 16 days, alen eliminated the 1,25D-induced increase in uCa in SD. However, in GHS alen decreased, but did not eliminate, the 1,25D-induced hypercalciuria, suggesting maximal alen cannot completely prevent the 1,25D-induced bone resorption in GHS, perhaps due to increased VDR. There was no consistent effect on mRNA expression of renal transcellular or paracellular Ca transporters. Urine CaP and CaOx supersaturation (SS) increased with 1,25D alone in both SD and GHS. Alen eliminated the increase in CaP SS in SD but not in GHS. If these results are confirmed in humans with IH, the use of bisphosphonates, such as alen, may not prevent the decreased bone density observed in these patients.

This study investigates the effects of Ca on bone in the ovariectomized mice. Twenty-six female ICR mice aged 5 weeks were used. They were ovariectomized (OVX) or sham-operated (SHAM) and fed standard mouse diet (SF) or special low calcium diet (L.Ca), respectively. All animals were sacrificed at day 100 after operation. Mechanical strength of the left femur and tibia was measured by the three-point bending strength test. The bones were dried, weighed and burned to ash. Correlation between mechanical strength and ash content was found. A specimen of the right tibia was prepared. Mechanical strength, ash content and ratio of dry bone weight to body weight of the femur and tibia in OVX and L.Ca mice were significantly less than in SHAM and SF mice. SHAM/SF mice and OVX/L.Ca group showed highest and lowest values in all cases. The values for the femur and tibia in OVX/SF mice were lower than in SHAM/SF group and in OVX/L.Ca group were less than in OVX/SF mice. Correlation coefficients for mechanical strength and ash content were 0.704 and 0.776 for the femur and tibia. Ca is thus related to inhibition of bone loss and maintenance of bone mass and effective prevention of osteoporosis.

The purpose of this study was to investigate the effects of Ca intake on bone for limited periods, 50 and 100 days, in ovariectomized and sham-operated mice. Fifty-six female 5-weeks-old ICR mice were used. Six mice were sacrificed at start of this study for the baseline. The remaining fifty mice were either ovariectomized (OVX) or sham-operated (SHAM), and mice of both groups were fed either standard mouse diet (SF) or special low calcium diet (L.Ca). Half of the animals were sacrificed at day 50 after operation and the rest at day 100. Maximum load of the femur and tibia were measured by the three-point bending strength test. The bones were dried and burnt to ash. Maximum load, ash content of the femur and tibia in OVX or L.Ca mice were significantly less than in SHAM or SF mice. SHAM/SF and OVX/L.Ca mice showed the highest and lowest values in maximum load and ash content, respectively. The effect of the term was shown in all parameters except for maximum load. Correlation coefficients between maximum load and ash content were 0.704 and 0.776 for the femur and tibia. Ca intake is thus related to inhibition of bone loss and maintenance of bone mass. This influence appeared slowly and had an additive effect with other factors, OVX and term.

We investigated the effects of short-term feeding low calcium diet on egg shell quality (specific gravity, relative weight of egg shell, egg shell thickness) and mRNA levels of calbindin-D28K (CaBP-D28K) in the shell gland and intestine. After feeding low calcium diet (0.5%), hens laid fragile eggs with low shell quality. Plasma calcium concentration also decreased significantly after feeding of low calcium diet. When the hens received a moderate calcium diet (3.5%) after low calcium diet for 5 days, shell quality was improved and plasma calcium concentrations increased. Levels of CaBP-D28K mRNA in the shell gland did not change after feeding low calcium diet for 5 days. Levels of CaBP-D28K mRNA in the intestine of the low calcium diet group significantly increased 2 fold when compared to those of the control group. We infer that low calcium concentration in plasma may stimulate parathyroid and 1, 25(OH)2D3 production in the kidney and induce CaBP-D28K mRNA expression in the intestine. It is supposed that a low calcium diet influences egg shell quality, plasma calcium concentration and intesti-nal CaBP-D28K gene expression by calcium homeostasis. In the shell gland, however, the levels of CaBP-D28K mRNA may not be influenced by low plasma calcium.

This experiment examined skeletal effects of moderate zinc (Zn) supplementation of a low-calcium diet. Male weanling rats were fed experimental diets for about 4 wk. One diet was adequate (control), whereas two others were calcium-deficient, but otherwise adequate. One of the low-calcium (Ca) diets was supplemented with Zn. Dimensions, weight, mineral content, and mechanical properties of femurs were measured. Ca deficiency reduced bone mineral content and strength markedly. Adding Zn to the low-Ca diet further reduced bone strength and elasticity, compared with the unsupplemented low-Ca diet. When the Ca intake is low, possible benefits of Zn supplements should be weighted against risk of deterioration of mechanical properties of bone.

This study investigates whether bisphosphonate-treated rats are still able to adapt to low calcium supply through an increase in bone resorption assessed by measuring the urinary excretion of [3H]-tetracycline from chronically prelabeled rats. First it was shown that in this model, parathyroid hormone was responsible for the increase in bone resorption on the low calcium diet. In the second part, animals were treated with the three bisphosphonates-clodronate, alendronate, and ibandronate-given in two doses. Animals receiving a dose that already strongly inhibits bone resorption were still able to respond to a low calcium diet by increasing bone resorption, showing the potency of the latter as a stimulator of bone resorption. Higher doses were, however, able to blunt this response. As soon as the treatment was discontinued, this increase in bone resorption resumed with clodronate but not with alendronate or ibandronate.

The interdependent influence of the protein and the calcium intake on bone health has been conclusively studied. For obtaining a positive bone effect from nutritional protein, an adequate calcium intake is required, and vice versa. A high-protein intake was first considered as potentially negative for bone, but this fear was not defendable anymore when it became evident that a high-protein intake increases urinary calcium excretion because it stimulates calcium absorption. Protein deficiency was shown to be detrimental to bone, not a high-protein intake. However, some large follow-up studies demonstrated that the combination of a high-protein intake with a low-calcium diet increases fracture risk. This particular nutritional profile seems to be rare, but some cross-sectional studies seem to confirm that.

Ten-month-old lactating breeders were ovariectomized and kept on a low calcium diet. One month after ovariectomy, the rats were dosed once daily for 6 months with either a low dose of growth hormone (GH) (0.05 mg), a high dose of GH (1 mg), estrogen plus gestagen (E-G) [17 beta-estradiol (0.1 mg); norethisterone-acetate (0.05 mg)], or a combination of GH and E-G. Mechanical competence, apparent dry density, apparent ash density and ash concentration were measured in the fourth lumbar vertebral body. The reduced mechanical strength, ash density and ash concentration found in the vertebral body of ovariectomized animals were prevented by the high dose of GH alone, or in combination with E-G. E-G alone partly prevented the decline in ash density and ash concentration, but did not affect the reduced mechanical strength seen after ovariectomy. Only minor effects were observed after treatment with the low dose of GH, alone or in combination with E-G. In conclusion this study shows that GH administration prevents the decline in mechanical strength and bone mineral density seen in rats after ovariectomy.

Made available in DSpace on 2013-08-12T19:12:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-01 Made available in DSpace on 2013-09-30T18:34:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:04:37Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T14:04:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Objective: The variety of methodologies used to investigate ovariectomized female rats shows different results, which makes a clinical application of these results difficult. The purpose of this work was to evaluate the effect of masticatory effort reduction and of low-calcium diet on maxillary bone turnover of ovariectomized female rats.Study Design: Eighty-four female rats were divided into four groups of 21 animals each as follows: SHAM - sham-operated; OVZ - ovariectomized and fed a standard commercial diet; LCD - fed a low calcium diet, and GCD - fed a grind commercial diet. The inferior first molars were extracted bilaterally 15 days after the ovariectomy, and the animals were euthanized 3, 5 and 8 weeks after ovaries removal. The maxillae were embedded in methylmetacrilate. The results were submitted to analysis of variance.Results: The daily mineral apposition rate lowered with time and was not different between SHAM and OVZ groups. The trabecular bone volume of SHAM and OVZ animals was similar and decreased with time. The GCD animals presented the lowest means and the LCD the highest in comparison to the OVZ group.Conclusion: It was concluded that ovariectomy and a low calcium diet did not cause significant maxillary bone loss in the first molar region, and even in the absence of the antagonist tooth, they did not cause maxillary bone turnover. The grind commercial diet is a good alternative for the study of maxillary bone loss in ovariectomized female rats. São Paulo State Univ UNESP, Sao Jose dos Campos Sch Dent, Dept Biosci & Oral Diag, São Paulo, Brazil Cruzeiro Super Sch ESC, Dept Phisioterapy, São Paulo, Brazil Fac Pindamonhangaba FAPI, Dept Anat, São Paulo, Brazil São Paulo State Univ UNESP, Sao Jose dos Campos Sch Dent, Dept Biosci & Oral Diag, São Paulo, Brazil FAPESP: 07/53807-8 FAPESP: 07/53806-1

The duodenal loop was excised from hens that had been induced to molt by a low-calcium diet containing 2,800 ppm zinc in the form of zinc sulfate heptahydrate. This was compared to that of hens pair-fed a layer diet. In Experiment 1, hens exhibited an increased duodenum weight after receiving the zinc diet for 14 days but no differences remained 14 days later. In Experiment 2, increased duodenum weight was noted after 4 days on the zinc diet and this persisted through 10 days. This greater tissue weight was observed whether expressed on a wet or dry weight basis. Thus, there was a persistency of tissue mass. The duodenum does not regress during a zinc-induced molt as it does during a fast-induced molt.

Three experiments were designed to test the hypothesis that zinc has a specific effect independent of anorexia during induction of molt. In Experiment 1, hens were fed a low-calcium (.08%) basal molt diet to which was added 0, 110, 620, or 1,120 mg/kg (ppm) zinc as zinc sulfate heptahydrate (ZnSO4·7H2 O) for 7 days and 0, 1,400, 2,800, or 4,200 ppm zinc, respectively, for the following 14 days. In Experiment 2, hens were provided ad libitum access to the low-calcium basal molt diet with 2,800 ppm added zinc for 14 days during which a paired control hen received a similar amount of the low-calcium basal molt diet. In Experiment 3, hens were fed the low-calcium basal molt diet on a restricted basis amended with either 0 or 2,800 ppm zinc on a restricted basis for 10 days. In Experiment 1, all hens that consumed zinc had significantly fewer days to last oviposition as compared with control hens, and this occurred without significant differences in body weight or feed consumption for the lowest zinc group. When compared with the control group, higher levels of zinc did decrease body weight and feed consumption. In Experiment 2, the hens consuming the diet with 2,800 ppm zinc (Zn2800) reached last oviposition significantly sooner than control hens, although the Zn2800 hens actually consumed more feed. In Experiment 3, the Zn2800 hens lost more body weight than control hens due partially to earlier reproductive tract regression. Serum luteinizing hormone was increased in the Zn2800 hens. In the absence of supplemental dietary calcium, dietary zinc in moderate concentrations (≤2,800 ppm) has a specific suppressing effect on reproduction independent of anorexia.

Vascular reactivity and systolic blood pressure (SBP) were studied in tail artery rings isolated from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive, Wistar-Kyoto rats (WKY). After a control week on a diet with 1% of calcium, the animals were randomly assigned to three groups, which were fed with 1% (control), 0.4% (low) or 2.5% (high) dietary calcium. Both vascular reactivity and SBP were studied in the same animal during 9 weeks after changing diets. In the SHRSP rats on high Ca diet, maximal contractile responses to norepinephrine and serotonin (10(-10) to 10(-4) M) and to KCl (5 to 105 mM) were markedly decreased at the end of the study with respect to the control diet. These vascular changes were accompanied by a decrease of SBP in the same animals. Low calcium diet prevented the age-related increase of SBP in SHRSP rats and produced vascular changes of a lesser magnitude. WKY rats showed no significant modifications of SBP or vascular reactivity. Since plasmatic Ca2+ levels were not altered, the changes detected could not be attributed to a direct depressant effect of high calcium on the vascular smooth muscle cell (i.e. a "stabilizing action" of calcium). It is speculated that high dietary calcium could modulate the synthesis of calcium binding proteins of the plasma membrane, decreasing vascular reactivity and the elevated vascular resistance which is usually present in hypertension.

Chiari malformation is commonly considered a congenital condition. To our knowledge, reports of progressively symptomatic Chiari Iota malformation with craniometaphyseal dysplasia are rare. The authors present a case of progressively symptomatic Chiari Iota malformation occurring in an 11-month-old infant with craniometaphyseal dysplasia. The patient presented with a typical facial appearance and radiological skeletal survey. Posterior fossa decompression was performed. In the meantime, the patient was given Rocaltrol (calcitriol) and adopted a low calcium diet. His neurological symptoms were markedly improved after surgery. The clinical presentations, radiographical features and prognosis of the patient are discussed with reference to the literature.

A high calcium intake has been shown to attenuate the degree of hypertension in spontaneously hypertensive rats (SHR) and some human hypertensives. Conversely, a low calcium intake has been associated with an increase in blood pressure in both groups. In the present study, the effects of a high (2%), medium (0.6%) and low (0.02%) calcium diet on mean arterial pressure (MAP) and on the expression of a novel circulating hypertensive factor--parathyroid hypertensive factor (PHF)--were examined in SHR. In rats on the low calcium diet, MAP and PHF activity were significantly higher at 8 weeks than in the other two groups. In the high calcium group, MAP was significantly lower than in the other two groups, although it was elevated compared to week 0 values. PHF activity was not detected in the plasma of this high calcium group. Overall, MAP was highly correlated with PHF activity (r = 0.78, P = .0001). These results suggest that the effects of dietary calcium on blood pressure in SHR may be mediated by a novel circulating hypertensive factor, PHF, such that a high calcium diet inhibits, and a low calcium diet stimulates, the expression of this factor.

The possibility that low-calcium intake in renal stone formers could lead to reduced bone mineral content was investigated in 123 male patients with idiopathic urolithiasis. Radius bone mineral content (BMC) was measured by single photon absorptiometry. Two groups of patients were analyzed: group 1 (n = 63) maintained on a free diet; group 2 (n = 60) maintained on a low-calcium diet (350 mg/day +/- 20 SEM) for 3.9 years +/- 0.6 SEM. The two groups of patients were investigated after a standard reduction of calcium intake for at least 1 week. The urinary excretion of calcium and of hydroxyproline, and the serum alkaline phosphatase activity were higher in both groups than in normal subjects submitted to the same low-calcium diet. Both groups of stone formers showed lowered radius BMC values at 3 cm (distal) and 8 cm (proximal) above the styloid process, but distal BMC was significantly lower in group 2 than in group 1. The results suggest that low-calcium intake could worsen the already decreased BMC of idiopathic renal stone formers., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

Objective: To investigate the effects of a low calcium diet on maxillofacial development by evaluating Bone Mineral Content (BMC) in the lower alveolar bones, femurs, and tibias and by performing cephalometry on growing rats. Materials and Methods: Thirty 5-week-old male Wistar rats were randomly divided into 3 groups; the control group (n = 10) was given standard diet for 6 weeks, the low calcium/standard diet group (n = 10) was given a calcium-restricted diet for the first 4 weeks, and then a standard diet for the following 2 weeks, and the low calcium diet group (n = 10) was given the calcium-restricted diet for 6 weeks. After the rats were euthanized, heads and legs were fixed and cephalometry was performed. Next, mandibles, femurs and tibias were digitally photographed and the BMC was evaluated using our newly developed software. Results: The BMC was decreased in all of the bone samples from the two groups that received restricted calcium. In the low calcium/standard diet group, the BMC recovered the most in the tibias and least in the lower alveolar bones. Development of the mandibles in the anterior-posterior direction was accelerated, while that in the superior-inferior direction was inhibited in those rats. Conclusion: The BMC reduction following calcium deficiency in the lower alveolar bone hardly recovers, so prevention is important. Development of the mandible in a superior-inferior direction is inhibited while that in an anterior-posterior direction is accelerated due to a calcium-restricted diet.

Increased calcium intake may reduce body weight and fat in non-growing individuals. This study explored the long-term effects of high versus low calcium intake on body weight, body fat, BMC, BMD and bone size in growing male and female rats. Ninety male and 90 female Sprague-Dawley rats were randomly assigned either to a high calcium (1%) or low calcium (0.25%) diet from age 3 weeks until 40 weeks. Half of the animals were fed ad libitum, and half of the animals were on an adjusted feeding schedule (the food intake of the low calcium animals was reduced to maintain equal body weight with high calcium animals of the same gender). DXA and radiographic measurements (femur and skull length and width) were collected at the age of 4, 13 and 34 weeks. Growing male rats fed the low calcium diet ad libitum gained more weight and more fat than rats on a high calcium diet. When food intake was controlled, male rats on the low calcium diet still had a greater fat mass (despite their similar body weight) and smaller skeletal measurements than the high calcium animals. Growing female rats initially responded like the males: when fed ad libitum low calcium animals had an increased body weight and fat mass; when food intake was controlled the low calcium animals had a greater fat mass and smaller skeletal measurements. However, these differences were found at 13 weeks and not at 34 weeks, suggesting a transient effect with no long-term differences between high and low calcium intake in the growing female rats.