Journal de la Societe de biologie最新文献

Although biological testing has nothing to do with the diagnosis of osteoporosis, it can help the physician to: 1) identify secondary causes of low bone mass and/or fracture. There is however currently no consensus to define the biochemical parameters to be measured in this case. The cost-effectiveness of the biological evaluation, that is, measuring a minimum of parameters to detect a maximum of anomalies needs to be considered. Most experts agree that malignancy and especially a myeloma should be ruled out, and that an evaluation of calcium/phosphorus metabolism including the measurement of serum calcium, phosphate, PTH and 25 hydroxy-vitamin D should be performed. This allows to detect many anomalies including two very frequent conditions, primary hyperparathyroidism and vitamin D deficiency. Note however that complementary testing is generally needed to identify other diseases; 2) evaluate efficacy and observance of some osteoporosis treatments especially oral bisphosphonates. In this case, the evolution of the blood or urine level of some markers of bone turnover over a 3-6 month period after the initiation of therapy will be considered. For example, a decrease of more than 30% in the serum concentration of CTX (C-terminal telopeptide of type I collagen) will be regarded as a significant change indicating that treatment has reduced bone resorption.

Osteoporosis is a bone disorder that leads to increased fracture risk. It was defined by the World Health Organisation as a decrease of bone mass and a deterioration of bone quality. In clinical practice, the diagnosis of osteoporosis is based on bone mineral density (BMD) measurements assessed by dual energy X-ray absorptiometry. However, BMD assessment is not the only factor that influences bone strength. The main objective is that clinicians can use a combination of risk factors that are easily assessable, for a better prediction of osteoporosis risk fracture. Bone strength reflects both bone density and bone quality. One of the most important determinants of bone quality is the trabecular bone micro-architecture as suggested by the definition of osteoporosis. Moreover, various studies have concluded to the potential clinical interest of the bone micro-architecture. The aim of this article was to review the challenges of bone micro-architecture, characterization tools (morphological analysis, topology, texture) and imaging techniques (X-ray imaging, scanning and MRI) to assess trabecular bone micro-architecture.

The human Y chromosome contains a number of genes and gene families that are essential for germ cell development and maintenance. Many of these genes are located in highly repetitive elements that are subject to rearrangements. Deletion of azoospermia factor (AZF) regions AZFa, AZFb, and AZFc are found in approximately 10-15% of men with severe forms of spermatogenic failure. Several partial AZFc deletions have been described. One of these, which removes around half of all the genes within the AZFc region, appears to be present as an inconsequential polymorphism in populations of northern Eurasia. A second deletion, termed gr/gr, also results in the absence of several AZFc genes and it may be a genetic risk factor for spermatogenic failure. However, the link between these partial deletions and fertility is unclear. The gr/gr deletion is not a single deletion but a combination of deletions that vary in size and complexity and result in the absence of different genes. There are also regional or ethnic differences in the frequency of gr/gr deletions. In some Y-chromosome lineages, these deletions appear to be fixed and may have little influence on spermatogenesis. Most of these data (gene content and Y chromosome structure) have been deduced from the reference Y chromosome sequence deposited in NCBI. However, recently there have been attempts to define these types of structural rearrangements in the general population. These have highlighted the considerable degree of structural diversity that exist. Trying to correlate these changes with the phenotypic variability is a major challenge and it is likely that there will not be a single reference (or normal) Y chromosome sequence but many.

It is well known that in Mammals, spermatogenesis requires a temperature lower than that of the body. In Ectotherms, for example in Insects, male sterility/ fertility according to environmental conditions also remains a neglected field. In Drosophila melanogaster, a complete male sterility after development at 30 degrees C was described in 1971. A similar phenomenon, observed at low temperature, was described two years later. Recent comparative investigations have shown that what was found in D. melanogaster was also valid in other species. In each case, it is possible to define a range of temperatures compatible with a complete development. According to the investigated species, however, this range is very variable, for example 6-26 degrees C or 16-32 degrees C. In each case, the occurrence of sterile males is observed before the lethality threshold is reached. Such a phenomenon is probably important for understanding the geographic distributions of species. The cosmopolitan D. melanogaster lives under very different climates and exhibits corresponding adaptations. In countries with a very hot summer, such as India or the African Sahel, male sterility appears only at 31 degrees C. Crosses between a temperate population from France and a heat-resistant Indian population revealed that a large part of the genetic difference was carried by the Y chromosome. Such a result is surprising since the Y chromosome harbors only a very small number of genes. In conclusion, drosophilid species, during their evolution, were able to adapt to very different climates and the thermal sterility thresholds have changed, following these adaptations. But we still lack an evolutionary hypothesis for explaining why sterile males are, in all cases, produced at extreme, low or high temperatures.

Sperm acrosome is known to play a role in the fertilization of the majority of animal species studied. As a general rule, the acrosome appeared as soon as the fertilization occurred out of aquaeous phase. The biochemical content of acrosome as well as its release mode could suggest it is a simple lysosome. But this would by pass its important morphogenic role in spermiogenesis. Its development is strongly linked to the development of the microtubules manchette system. Molecular data of animal mutagenesis contribute to the understanding of acrosome biogenesis mechanisms. Globozoospermia is a rare but severe human teratozoospermia, characterized by ejaculates entirely consisting of round-headed spermatozoa that lack an acrosome. It originates from a disturbed acrosome biogenesis. Recently, the genetic study of a familial globozoospermia led to highlight a homozygote mutation of the gene SPATA16, linked to the globozoospermic phenotype. This study contributes to the understanding of the mechanisms implied in human acrosome formation.

Ex vivo cutaneous gene therapy is an alternative treatment for recessively inherited diseases with cutaneous traits. It relies on the transfer in cultured epidermal keratinocytes of the wild-type allele of the gene whose mutation is responsible for the disease. As for severely burnt patients, epithelial sheets developed from genetically corrected cells may then be grafted back to the patients. Long term correction and graft take depend on the genetic correction of stem cells. Success of such an approach has recently been reported in the case of one patient suffering from a severe case of junctional epidermolysis bullosae. Here we report a method for safely selecting keratinocytes populations after genetic manipulation. The method is non invasive and non immunogenic and allows high enrichment of genetically manipulated stem keratinocytes. This could perhaps contribute to ex vivo gene therapy approaches of cancer prone genodermatoses such as xeroderma pigmentosum.

Osteoporosis leads to fragility fractures. Fracture incidence increases after the menopause among women and with age in both genders. More than 40 % of women will sustain at least one fragility fracture after the age of 50. Many risk factors have been described, including age, familial history of fracture, low bone mineral density, personal history of fracture, smoking and low body mass index. Fracture incidence is increasing worldwide, owing to population aging. Hip and vertebral fractures are associated with increased mortality and morbidity. Costs related to fragility fractures represent a significant burden for health care systems.