Time Course of Recruitment, Pit Formation and Apoptosis of Osteoclast Populations on Dentin In Vitro

The resorptive capacity of osteoclasts in vitro has been used as an indicator of bone resorption. However, the kinetics of osteoclast development and senescence is not well understood. It has been noted that mononuclear precursors migrate to calcified substrate and after multi-nucleation become competent bone resorbing cells. Osteoclasts, once finished a wave of resorption, become senescent. In order to determine the survival characteristics of osteoclast populations involved in calcified tissue destruction, we have investigated the time course of the recruitment to dentin and apoptosis of osteoclasts. We have established the linkage between these measurements and the time course of the appearance of pits using both chick and rat osteoclasts in vitro. Osteoclasts from both species caused increases in pit number associated with decreases in cell number on dentin. In the rat model, we have used a fluorescent linker to mark cells before they migrate to dentin and have shown that cells can be followed from the culture dish onto the dentin disc. In the chick model, we have used time lapse cinematography and fluorescent nuclear staining to observe death of osteoclasts on dentin and have established an osteoclast half live in vitro

Postpartum maternal morbidity requiring hospital admission in Lusaka, Zambia – a descriptive study

BACKGROUND: Information on the extent of postpartum maternal morbidity in developing countries is extremely limited. In many settings, data from hospital-based studies is hard to interpret because of the small proportion of women that have access to medical care. However, in those areas with good uptake of health care, the measurement of the type and incidence of complications severe enough to require hospitalisation may provide useful baseline information on the acute and severe morbidity that women experience in the early weeks following childbirth. An analysis of health services data from Lusaka, Zambia, is presented. METHODS: Six-month retrospective review of hospital registers and 4-week cross-sectional study with prospective identification of postpartum admissions. RESULTS: Both parts of the study identified puerperal sepsis and malaria as, respectively, the leading direct and indirect causes of postpartum morbidity requiring hospital admission. Puerperal sepsis accounted for 34.8% of 365 postpartum admissions in the 6-month period. Malaria and pneumonia together accounted for one-fifth of all postpartum admissions (14.5% & 6% respectively). At least 1.7% of the postpartum population in Lusaka will require hospital-level care for a maternal morbidity. CONCLUSIONS: In developing country urban settings with high public health care usage, meticulous review of hospital registers can provide baseline information on the burden of moderate-to-severe postpartum morbidity

Quantitation of acid phosphatase in individual bone cells

Note:Analysis of physiological and biochemical responses of bone tissue has been hampered by the inherent inaccessibilityof the cells within. The problem is compounded by the heterogeneity of bone cell types as well as the largenumber of marrow cells present but presumably unconnected with the basic bone metabolism.This work presents the development of a method of measuring enzyme activity, in particular acid phosphataseactivity, in individual bone cells in a smear preparation, with the aid of microdensitometry via computer-linked imageprocessor. In rat models of Vitamin D deficiency and repletion including the use of the Vitamin D active metabolite1,25-dihydroxycholecalciferol, as well as several models of altered calcium and parathyroid hormone, thetechnique has shown increased activity of acid phosphatase in osteoclasts and osteoblasts to increased levels ofVitamin D. Neither alterations in ingestion of calcium nor injection of parathyroid hormone were shown to change enzyme activity.L'analyse des réponses physiologiques et biochimiques des os se fait difficilement à cause de leur dureté et a cause de l'hétérogénéité de leur cellules. Un autre problème se pose dans l'étude des os: il y a au même endroit d'autres cellules qui ne participent pas au métabolisme des os. Une méthode d'évaluation quantitative de l'activité des enzymes, en particulier la phosphatase acide, dans des cellules osseuses individuelles sur frottis a été développée à l'aide d'un ordinateur programme pour l'analyse micro-densitometrique des images microscopiques. Dans plusieurs modèles chez le rat prive de vitamine D et/ou traits avec la vitamine D ou le métabolite active, 1,25-dihydroxycholecalciferol, on a pu montrer une augmentation de l'activité de l'enzyme phosphatase acide dans les ostéoclastes et les ostéoblastes. Ni la quantité de calcium n’ingère ni l'injection d'hormone parathyroïdienne n'ont affects l'activité enzymatique