Partial rescue of the Dazl knockout mouse by the human DAZL gene

Y-chromosomal DAZ (deleted in azoospermia) and autosomal DAZ-like (DAZL) comprise a gene family involved in gametogenesis. Y-chromosomal and autosomal genes only co-exist in humans and old world monkeys, indicating that DAZ genes are a recent acquisition of the Y chromosome. In most mammals, the ancestral Dazl alone is sufficient to complete gametogenesis. It is not yet understood why humans and old world monkeys have a second set of genes that are apparently necessary for spermatogenesis, since deletions removing the Y-chromosomal DAZ are often associated with azoo- or oligospermia. We used transgenic mice carrying either human DAZL or human DAZ on a mouse Dazl null background to investigate the functions of the human homologues. Both transgenes enabled prophase spermatocytes to be produced, mainly of the leptonema/zygonema stage, but failed to promote differentiation into mid- to late pachytenes. The presence of human DAZL resulted in a larger amount of early germ cells compared with that observed in DAZ. The degree of rescue was independent of copy number, integration site or presence of the DAZ repeat region for the DAZ transgenes. These findings confirm that DAZL and DAZ can only substitute for early functions of the murine homologue resulting in the establishment of the germ cell population and partial progression into meiosis.     

Frequency of cytokine polymorphisms in populations from western Europe,Africa, Asia,the Middle East and South America

PCR-SSOP identification procedures for IL-2, IL-6, IL-10, TNF-alpha and TNF-beta cytokine polymorphisms have been developed. Application of the procedures to a range of diverse geographically distributed populations has identified ethnic differences within the groups studied. Five populations were investigated, Northern Ireland, South African Zulu, Omani, Singapore Chinese and Mexican Mestizos.     

Myeloperoxidase deficiency. Increased sensitivity for immunocytochemical compared to cytochemical detection of enzyme

The discovery of hereditary deficiency of myeloperoxidase (MPO) in neutrophils and monocytes of affected individuals has been based on the absence of cytochemical staining in these peripheral blood cells. We report that an immunocytochemical method shows more sensitivity than either the benzidine or 4-chloro-1-naphthol cytochemical methods. In MPO-deficient subjects, immunocytochemistry detects a marked decrease, but not absence, of MPO.     

Evaluation of bacteriological swabs and transport media in the recovery of group B streptococci on laboratory media.

The survival of group B streptococci on a variety of swabs, held either in their containers or in transport media for periods of up to 48 hours, at room temperature and at 4 degrees C, has been assessed. Results indicated that holding swabs in transport media did not favour prolonged survival of the streptococci and that the yield of organisms was much greater from swabs held in their ordinary plastic tubes. A holding temperature of 4 degrees C rather than room temperature is recommended if any delay in plating out swabs is anticipated.     

Population-based laboratory surveillance for tribe Proteeae isolates in a large Canadian health region

The tribe Proteeae comprises the genera Proteus, Morganella and Providencia. Few studies have specifically investigated the epidemiology of infections caused by the Proteeae, and none has been conducted in a large non-selected population. The present study was a population-based laboratory surveillance in the Calgary Health Region (population 1.2 million), Canada during 2000-2005 that aimed to define the incidence, demographical risk-factors for acquisition and antimicrobial susceptibilities of Proteeae isolates. In total, 5047 patients were identified from whom Proteeae isolates were obtained (an annual incidence of 75.9/100 000), with females and the elderly being at highest risk. Incidence rates were 64.8, 7.7 and 3.4/100,000/year for the genera Proteus, Morganella and Providencia, respectively. Overall, 85% of infections were community-onset, and the overall rate of bacteraemic disease was 2.0/100,000. Compared with other species, Proteus mirabilis occurred at a much higher frequency, especially among females, and was less likely to be isolated from hospital-onset infections or to be part of a polymicrobial infection. Among isolates from community-onset infections, Providencia spp. were less likely to be from outpatients and more likely to be from nursing home residents. There were low overall rates of resistance to ciprofloxacin (4%) and gentamicin (5%), with Prot. mirabilis generally being the most susceptible. Members of the Proteeae were isolated frequently in both the community and hospital settings, but were infrequent causes of invasive disease. The occurrence, demographical risk-factors and microbiology of Proteeae isolates varied according to the individual species.