73 resultados para Calcium
Resumo:
Development of new biodegradable implants and devices is necessary to meet the increasing needs of regenerative orthopedic procedures. An important consideration while formulating new implant materials is that they should physicochemically and biologically mimic bone-like properties. In earlier studies, we have developed and characterized magnesium based biodegradable alloys, in particular magnesium-zirconium (Mg-Zr) alloys. Here we have reported the biological properties of four Mg-Zr alloys containing different quantities of strontium or calcium. The alloys were implanted in small cavities made in femur bones of New Zealand White rabbits, and the quantitative and qualitative assessments of newly induced bone tissue were carried out. A total of 30 experimental animals, three for each implant type, were studied, and bone induction was assessed by histological, immunohistochemical and radiological methods; cavities in the femurs with no implants and observed for the same period of time were kept as controls. Our results showed that Mg-Zr alloys containing appropriate quantities of strontium were more efficient in inducing good quality mineralized bone than other alloys. Our results have been discussed in the context of physicochemical and biological properties of the alloys, and they could be very useful in determining the nature of future generations of biodegradable orthopedic implants.
Resumo:
Aim
In a sample of older women, we assessed the proportion who met the estimated average requirement (1100 mg/day) for calcium and the dietary food choices that achieved calcium adequacy. We also assessed if the diets adequate in dietary calcium were consistent with the other dietary recommendations for health.
Methods
Baseline data from women aged 50+ years who were recruited for dietary intervention studies were included as a proxy for usual intake. Analyses of usual food and nutrient intake were derived from two 24-hour recalls.
Results
Women (n = 145) aged 50+ years (mean age 59.3 (SD 5.5) years, mean calcium intake of 815 (323) mg calcium/day) participated. Approximately one-fifth met the estimated average requirement for calcium (21%, n = 31); among this group, dairy products contributed to 61% of calcium intake (mean 2.8 (SD 1.0) servings/day). Milk contributed 33% (425 mg) of total dietary calcium. Three per cent consumed skim milk only. Both groups (calcium adequate/inadequate) exceeded the suggested dietary target (≤10%) recommended for percent energy from saturated fat, 13.4% (3.7%) and 11.7% (3.5%), respectively. In the adequate group, if skim milk replaced full-fat and reduced-fat milk, then percent energy from saturated fat would fall by 3% (from 13.4% of energy to 10.4% of energy).
Conclusions
Consumption of at least 2.8 servings/day of dairy products is likely to ensure an adequate calcium intake (>1100 mg) in women over 50 years. However, to ensure saturated fat remains at recommended levels, usual consumption of full-fat and reduced-fat milk should be replaced with skim milk.
Resumo:
Aim:
Materials & methods:
Chondrocytes exposed to IL-1beta and osteoarthritis chondrocytes grown in an ex vivo inflammation-based coculture were incubated with different concentrations of herbals, and cell modulatory activities were determined. For in vivo studies, herbals and their encapsulated nanoformulations were administered orally to DBA/1 mice with collagen-induce arthritis.
Results:
C. quadrangularis and LG showed enhanced chondroprotective and proliferative activity in IL-1beta-exposed primary chondrocytes, with LG showing the highest therapeutic potency. LG increased viability, proliferative and mitogenic activity, and inhibited cell apoptosis and mitochondrial depolarization. In vivo studies with LG and alginate-enclosed chitosan-calcium phosphate LG NCs revealed cartilage regenerative activity in those administered with the nanoformulation. The NCs were nontoxic to mice, reduced joint swelling and paw volume, and inhibited gene expression of MMPs and cytokines.
Conclusion:
The promising results from this study reveal, for the first time, the novel polymeric NC encapsulating LG as a potential therapeutic for rheumatic diseases. Original submitted 10 October 2013; Revised submitted 13 December 2013.
Resumo:
Objective : Supplementing pregnant women at high risk of developing pre-eclampsia with calcium may reduce the incidence of the disease. This study examines differences in serum and hair concentrations of calcium and magnesium between women with pre-eclamptic and normotensive pregnancies.Design : Observational case–control study.Setting : Two teaching hospitals in Cape Town, South Africa.PopulationWomen with pre-eclamptic (N = 96) or normotensive (N = 96) pregnancies, who delivered a single, live infant.MethodsDemographic and current pregnancy details were retrieved from clinical notes. Each participant completed a dietary questionnaire. Venous blood samples were taken from each participant to assess serum calcium and magnesium concentrations. Hair samples were obtained from all participants and calcium and magnesium levels were measured by inductively coupled plasma optical emission spectrometry (ICPOES).Main outcome measureHair and serum calcium and magnesium concentrations were compared between women with pre-eclamptic and normotensive pregnancies.ResultsDiet and socio-economic status in the two groups were similar. There was no significant difference in the hair calcium level between women with pre-eclamptic [1241 parts per million (ppm); range, 331–4654 ppm] and normotensive (1146 ppm; range, 480–4136 ppm) pregnancies (P = 0.5). Hair calcium levels in both groups were not affected by HIV infection.ConclusionWoman with pre-eclampsia showed no difference in chronic calcium status relative to normotensive women. This finding does not support the current belief that the mechanism by which calcium supplementation reduces the risk of developing pre-eclampsia is by correcting a nutritional deficiency.
Resumo:
This paper describes a method using attenuated total reflectance infra-red spectroscopy to determine the surface concentration of calcium carbonate in paper samples, by applying the linear relationship between the relative infra-red absorption integrals and the concentration. The method was able to detect micro-variations in the surface concentration and could also distinguish between different sheets as well as between the top and bottom side of one sheet. The samples were also split and the calcium carbonate concentration was determined within and compared to bulk calcium carbonate concentration determined from ash testing. The surface results were also compared with analysed scanning electron microscopy images generated from back-scattering electrons. The comparison shows that both sets of results are in excellent agreement. Depending on the sample, large errors (95% confidence) were observed. These, however, are caused by micro-variations of the surface concentration, rather than by inaccuracies of the technique, which is estimated to be less than 1%. Furthermore, measurements of various sample orientations suggest that anisotropic polarisation effects can be neglected. The method can be applied to paper and cellulose matrices having calcium carbonate filler contents of less than 50%. Due to spectral overlaps it is not suitable to determine kaolin filler contents.
