Prevalence of renal stones in a population-based study with dietary calcium, oxalate, and medication exposures

Little is known about the epidemiology of renal stones, in spite of the relative frequency of this painful condition. This population-based study examined reported renal stone diagnosis in 1,309 women aged 20-92 years to determine whether renal stones are associated with 1) food or water exposures or 2) lower bone mineral density and an increased likelihood of fractures. Results indicated a renal stone prevalence of 3.4%. The average age at diagnosis was 42 years. Renal stone formation was not associated with community of residence, hypertension, bone mineral density, fractures, high-oxalate food consumption, or ascorbic acid from food supplements. Women with renal stones consumed almost 250 mg/day less dietary calcium (p < 0.01) than did women without stones and had a lower energy intake (p < 0.04). The authors' findings do not support the hypothesis that increased dietary calcium is associated with a greater prevalence of renal stones, nor do they identify renal stones as a risk factor for low bone mineral density. Furthermore, lack of other identifiable environmental correlates and the relatively young age at initial diagnosis suggest that genetic components of renal stone formation need further study.     

Activation of large-conductance potassium channels in pregnant human myometrium by pinacidil

OBJECTIVE: The aim was to investigate the effects of the potassium-channel opener pinacidil on single uterine potassium channels and the contribution of the latter to pinacidil-induced myometrial relaxation. STUDY DESIGN: Myometrial strips and freshly dispersed uterine myocytes were prepared from the myometrial biopsy samples of women undergoing elective, nonlabor caesarean section at term gestation. RESULTS: In isometric tension experiments pinacidil potently relaxed pregnant nonlabor human myometrial strips, with an agonist concentration yielding the half maximal response of 0.4 +/- 0.1 micromol/L. This effect was antagonized by 500 nmol/L charybdotoxin. Application of 10 micromol/L glibenclamide also inhibited the pinacidil-induced relaxation. Coapplication of charybdotoxin (500 nmol/L) and glibenclamide (10 micromol/L) produced a biphasic curve, which was fitted to a two-site model with values for agonist concentration yielding the half maximal response of 0.6 +/- 0.2 micromol/L and 189.7 +/- 0.8 micromol/L. Large-conductance calcium-dependent potassium channel activity was dramatically increased after application of pinacidil (between 10 and 100 micromol/L) to both inside-out and outside-out patches. The activation required the presence of calcium ions at the intracellular aspect of the membrane. Charybdotoxin but not glibenclamide blocked pinacidil-induced unitary large-conductance calcium-dependent potassium channel activity. CONCLUSION: Pinacidil-mediated relaxation of human pregnant myometrial strips may be partially attributable to the opening of uterine large-conductance calcium-dependent potassium channels in addition to adenosine triphosphate potassium channel activation. Drugs with specific potassium channel-activating properties may have important clinical application as novel tocolytics in the treatment of preterm labor.     

Increased incidence of spina bifida occulta in fluorosis prone areas

Spina bifida, a congenital deformity of the posterior wall of vertebrae of the spine, is a midline defect of skin, vertebral arches and neural tube, usually in the lumbosacral region. Its incidence is reported to be 0.2 to 0.4 per 1000 live births. Various hypotheses have been put forward as etiological factors for spina bifida including consumption of potato affected by blight and hardness of drinking water but these have not been proven. Two groups of 50 randomly chosen children were established. The study group consisted of children aged 5 to 12 years, weighing 15 to 30 kg, consuming fluoride rich drinking water (4.5 and 8.5 ppm fluoride; WHO permissible limit is 1.5 ppm fluoride), and manifesting either clinical, dental and/or skeletal fluorosis. The control group consisted of age and weight-matched children, consuming less than or equal to 1.5 ppm fluoride in drinking water and not showing any evidence of fluoride toxicity. These children were evaluated for antenatal history, general clinical examination (especially for dimples, tufts of hair, haemangioma on skin throughout the length of spine), other congenital abnormalities, evidence of fluoride toxicity, biochemical estimation for fluoride levels in blood and serum and by skiagrams of the spine to examine for the presence of spina bifida occulta. A total of 22 (44%) of the 50 children in group A, the study group, and 6 (12%) of the 50 children in group B, the control group, revealed spina bifida occulta in the lumbosacral region.(ABSTRACT TRUNCATED AT 250 WORDS)     

一种接入信息高速公路的新技术ADSL

新近出现的非对称数字用户线（ＡＤＳＬ）技术利用用户网中现有的铜双绞线提供１．５～６Ｍｂ／ｓ的下行数字信道，为接入信息高速公路提供了一条新途径，本文首次论述ＡＤＳＬ的基本概念，技术，发展现状和应用，最后论述我们对发展我国ＡＤＳＬ接入设备的几点建议。