Definition of the limits of the Wilms tumor locus on human chromosome 11p13

In a previous report, we described a contiguous restriction map of chromosome band 11p13 that localized the Wilms tumor locus to a small group of NotI fragments. In an effort to identify and isolate the 11p13-associated sporadic Wilms tumor locus, we developed a panel of NotI fragment-specific DNA probes. These probes were selected from genomic libraries constructed using the Chinese hamster ovary-human somatic cell hybrid carrying only human 11p. The libraries were prepared from NotI-digested DNA after size selection by pulsed-field gel electrophoresis. The selected NotI fragments had been previously targeted on the basis of deletion mapping as having a high probability of containing the Wilms tumor locus. We used these newly identified 11p13-specific probes to improve the resolution of the restriction map spanning the Wilms tumor locus. The locus has been defined by a homozygous deletion in a sporadic Wilms tumor. Using these probes, the region of homozygous deletion in this tumor and presumably all or part of the Wilms tumor gene have been confined to two small SfiI fragments spanning less than 350 kb.     

Outcome of breech delivery at term.

OBJECTIVE--To compare neonatal mortality and morbidity in term infants presenting by the breech and delivered vaginally or by caesarean section. DESIGN--Population based comparison of outcomes. Data derived from the St Mary''s maternity information system. SETTING--North West Thames Regional Health Authority, 1988-90. SUBJECTS--3447 singleton fetuses presenting by the breech at term. MAIN OUTCOME MEASURES--Intrapartum and neonatal mortality, low Apgar scores, intubation at birth, and admission to special care baby units. RESULTS--After the exclusion of babies with congenital anomalies the incidence of intrapartum and neonatal death associated with vaginal birth was 8/961 (0.83%) compared with 1/2486 (0.03%) in babies born by caesarean section (relative risk 20, 95% confidence interval 2.5 to 163). The numbers of low Apgar scores and neonatal intubation were doubled in babies born vaginally or by emergency caesarean section compared with those delivered by elective operation. CONCLUSIONS--The good neonatal outcome associated with elective caesarean delivery of the term breech fetus may influence the decision of women and their obstetricians about mode of delivery.     

Studies of the induction of dominant lethals and translocations in male mice after chronic exposure to microwave radiation

Male C3H mice were exposed to 100 W m-2 of 2.45 GHz continuous-wave microwave radiation for 6 h per day for a total of 120 h over an 8-week period. The exposure level was chosen so that the specific energy absorption rate (SAR) would be approximately equal to the level of 4 W kg-1 which is considered by a number of organizations to be a threshold for adverse biological effects. At the end of the treatment period the mice were mated with a different group of (C3H x 101) F1 hybrid females each week for the following 8 weeks. There was no significant reduction in pregnancy rate, preimplantation survival or postimplantation survival in the exposed group compared to sham-exposed controls. At the end of the mating period a cytogenetic analysis was carried out of meiotic chromosome preparations of testicular tissue, thus sampling cells that were stem cell spermatogonia during the treatment regime. The results showed no difference in the frequency of reciprocal translocations between the sham and treated groups, or in the frequency of cells with autosome or sex chromosome univalents. Low levels of fragments and exchanges were found in both groups. It is concluded that there is no evidence in this experiment to show that chronic exposure of male mice to 2.45 GHz microwave radiation induces a mutagenic response in male germ cells. This conclusion is in agreement with the observations of Berman et al. (1980), who reported a lack of male germ cell mutagenesis after repetitive or chronic exposure of rats to 2.45 GHz.     

Chromosomal localization of the human alpha 1-antitrypsin gene (PI) to 14q31-32.

In situ hybridization of a recombinant cDNA probe containing the human alpha 1-antitrypsin gene to metaphase chromosomes demonstrated significant hybridization to chromosomal segment 14q31-32. A high percentage of cells analyzed (31%) displayed labeling on chromosome 14. Of all labeled sites on chromosome 14, 60% were found on segment 14q31-32. These results refine the previous assignment of the human alpha 1-antitrypsin gene to segment 14q24.1-32.1.     

Human 2-5A synthetase: characterization of a novel cDNA and corresponding gene structure.

The enzyme 2-5A synthetase is induced in cultured cells in response to interferon (IFN) treatment. A lambda gt10 cDNA library of mRNA from IFN-induced Daudi lymphoblastoid cells was screened with oligonucleotide probes. Several overlapping cDNAs were isolated and shown to be derived from the human synthetase gene using filter selection and oocyte microinjection assays. The nucleotide sequence of one of these, cDNA 8-2, extended the 2-5A synthetase sequence already described 72 bp in the 5' direction but was found to differ significantly in coding sequence at the 3' end. The longest cDNA isolated (6-2) was approximately 1.4 kb. By Northern hybridization analysis single mRNAs of 1.7 kb were detected in Daudi and T98G (glioblastoma) cells. However, in HeLa cells, four mRNAs ranging in size from 1.5 to 3.5 kb were found, one of which differed at the 3' end. Analysis of both phage and cosmid genomic clones and comparison with genomic DNA indicate that there is a single gene for 2-5A synthetase, comprising at least six exons and five introns, which can undergo a novel form of alternative RNA processing depending on cell type.     

Ozone inhibits prostacyclin synthesis in pulmonary endothelium

The effects of ozone on lung arachidonate metabolism in-vitro were studied in cultured bovine pulmonary endothelial cells exposed for 2 hours to ozone in concentrations up to 1.0 ppm. A concentration-dependent decrease in prostacyclin synthesis was found (90% decrease at the highest ozone level of 1.0 ppm). The inhibition of prostacyclin synthesis was not due to a decreased release of arachidonic acid from membrane lipids. We also examined the hypoxic pulmonary vasoconstrictive response to 10% oxygen inhalation in anesthetized dogs in-vivo after exposure to 1.0 ppm ozone for 1 hour. Pulmonary vascular resistance was significantly increased after ozone exposure, similar to the findings in dogs given indomethacin (15 mg/kg). The percentage change in the hypoxic pulmonary pressor response was similar between the ozone exposure and indomethacin-treated groups, although due to the variance of the pulmonary vascular resistance values during hypoxia the results did not reach statistical significance. These results suggest that ozone inhalation affects pulmonary endothelial arachidonate metabolism in-vivo as well as in-vitro.     

Regulated expression of a Drosophila melanogaster heat shock locus after stable integration in a Drosophila hydei cell line.

DNA-mediated cotransformation has been used to transfer a Drosophila melanogaster heat shock locus into cultured Drosophila hydei cells by use of the copia-based selectable vector pCV2gpt and of pMH10A, a cloned 87A7 heat shock locus encoding a mutant heat shock protein (hsp). Transformed lines contain between 50 and 200 copies of both plasmids, each separately organized as a head-to-tail concatemer which is stably maintained in the transformed lines. Exposure of the cotransformants to heat shock temperatures induces the regulated expression of the hsp RNA and the mutant hsp in all the lines analyzed.     

Use of chromosomal integration in the establishment and expression of blaZ, a Staphylococcus aureus beta-lactamase gene, in Bacillus subtilis

With several different vectors, attempts were made to establish blaZ, a Staphylococcus aureus beta-lactamase gene, in Bacillus subtilis. Stable establishment of blaZ in B. subtilis was achieved by use of a vector that allowed the integration of a single copy of the gene into the chromosome of that host. blaZ was expressed in the heterologous host since B. subtilis strains carrying integrated blaZ produced beta-lactamase and were more resistant to ampicillin than was wild-type B. subtilis. blaZ was stably inherited in such strains, as no loss of the ability to produce beta-lactamase was observed after growth in nonselective liquid medium or on solid medium. In contrast, a blaZ-containing restriction fragment could not be established in B. subtilis with either pUB110- or pC194-based vectors. Similarly, a pC194-based shuttle vector (pGX318) containing the 5' end of blaZ (including the promoter and the coding region for the signal sequence and the first few amino acids of the mature protein) was unable to transform B. subtilis. Two derivatives of pGX318 that could be stably established in B. subtilis were isolated. The structures of these derivatives suggested that inactivation of the blaZ promoter was associated with the acquisition of the ability to be established.