Mapping of within-species segregation distortion in Drosophila persimilis and hybrid sterility between D. persimilis and D. pseudoobscura.

In contrast to the prevailing dogma in the 1990s, recent studies have suggested that an evolutionary history of segregation distortion within species may contribute to sterility in species hybrids. However, this recent work identified segregation distortion exclusively in species hybrids that may never have had an evolutionary history of segregation distortion in either parent species. We expand on previous work using a strain of Drosophila persimilis exhibiting segregation distortion within species to generate QTL maps for segregation distortion and hybrid sterility in crosses between D. persimilis and D. pseudoobscura. The maps localize regions along the XR contributing to both phenotypes, and they indicate one region of overlap between the two maps. This overlap could provide preliminary evidence for an association between segregation distortion within species and hybrid sterility, but the localizations are currently too broad to have confidence in this conclusion. This work is a first step towards possibly supporting a genetic conflict model of speciation in this system.

Imaging of primary non-Hodgkin's lymphoma of the liver.

AIM: To describe the radiological findings in primary liver lymphoma, which is a rare entity, presenting usually as a localized liver mass. MATERIALS AND METHODS: We reviewed retrospectively the imaging findings at presentation, of patients in whom a diagnosis of primary liver lymphoma was finally made histologically. The study period covered a 10-year period between January 1990 and December 1999. There were seven patients, all men, with a mean age of 49.6 years. Each patient presented with hepatobiliary disease without peripheral adenopathy. Imaging prior to diagnosis included ultrasonography (seven patients), computed tomography (seven patients) and magnetic resonance imaging (MRI) (two patients). Appearances during and after aggressive chemotherapy were reviewed. RESULTS: Imaging appearances were of either single or multiple liver lesions simulating liver metastases. On ultrasound all foci of primary hepatic lymphoma (PHL) were hypoechoic relative to normal liver. Computed tomography (CT) showed hypoattenuating lesions in all cases, and two cases showed rim enhancement following contrast administration. The MRI appearances were variable, and no pathognomonic feature of PHL was identified, so that histology was required in all patients to establish the diagnosis. CONCLUSIONS: This paper demonstrates the spectrum of findings encountered on various imaging modalities in PHL. We conclude that although PHL is a rare condition, it should always be considered in the differential diagnosis of liver metastases when no primary tumour is apparent.

Accessibility of cigarettes to minors in suburban Cook County, Illinois.

This study assessed the problem of under age sale of cigarettes, educated vendors about the law restricting the sale of tobacco to minors, and determined the effectiveness of a vendor education intervention. Twenty-one teen volunteers, 14 to 17 years in age, attempted to purchase cigarettes in suburban Cook County from over-the-counter merchants and vending machines. Of the 347 vendors that were checked, the minors were successful in 37.2% of their attempts to purchase cigarettes. After information was sent to each vendor about the State of Illinois law, follow up visits were made to all the vendors who were willing to sell cigarettes to the minors during the first visits. Approximately 50% of the vendors were again willing to sell cigarettes to minors. This study's findings suggest that minors can easily purchase cigarettes in suburban Cook County. The education intervention component of the study had a limited but promising effect on compliance rates of the vendors.