Strong linkage disequilibrium between the XY274 polymorphism and the pseudoautosomal boundary

The pseudoautosomal boundary is defined by an Alu repeat element on the Y chromosome. The Alu element is found on all Y chromosomes and on no X chromosomes, establishing it as part of Y-specific sequences. Distal to the Alu element, sequences from the X and Y are strictly homologous, suggesting that the boundary is formed by an abrupt break in sequence homology. Further investigation of the function of the boundary has been undertaken by examining the population structure of an MspI restriction-site polymorphism (XY274), which is located 274 bp distal to the Alu insertion site. Southern blot and polymerase chain reaction analysis demonstrate fixation of the high allele (noncutting or AT base pair) of XY274 on the Y chromosome in most populations, while a full range of high allele frequencies is found on the X chromosomes of different populations. Two exceptions to fixation on the Y chromosome were found in African populations. The level of linkage disequilibrium suggests that the first few hundred base pairs of the pseudoautosomal region on the Y chromosome share a single common origin more recent than the origin of the species.

Outbreak of multiply resistant Staphylococcus aureus in a pediatric intensive care unit after consolidation with a surgical intensive care unit

Patients in a pediatric intensive care unit were placed with patients in an adult surgical intensive care unit (SICU) in a large, 12-bed room previously occupied exclusively by the adult patients. The occurrence of multiply resistant Staphylococcus aureus (MRSA) in pediatric patients increased from zero cases during the preceding 12 months to seven cases (p less than 0.001) for the 95 days that the units were combined. The rate of acquisition of MRSA by the patients in the SICU remained unchanged. Pediatric patients who acquired MRSA had longer lengths of stay (p less than 0.001) and underwent more surgical (p less than 0.01) and invasive procedures than did pediatric patients who did not acquire MRSA. Removal of the pediatric patients to their own unit returned their rate of MRSA acquisition to the previous low level.

Computer systems to support census geography

The development of computer systems that support the geography of the census in Canada is described. The authors "present proposals for the 1991 Census that increase the level of automation, whether the geography changes or not. In addition, opportunities for change and improvement, should the geography change, are outlined. To minimize the risks involved, it is important to give these different proposals serious consideration early in the planning of a census."

Behavioral toxicity of acute and subacute exposure to triethyltin in the rat

The behavioral effects of both acute and subacute triethyltin (TET) exposure were examined in the rat. Animals acutely exposed to TET at doses of 0, 1.5 and 3.0 mg/kg showed a dose-related decrease in motor activity when tested between 2 and 4 hr following exposure. Subacute (3 week) exposure to TET in the drinking water (5 or 10 ppm) resulted in performance decrements in the following: maze activity, open field behavior, acoustic startle response and landing foot-spread. Early signs of behavioral deficits were observed 2 weeks after 10 ppm TET. These effects were reversible within one month after termination of exposure.