Selective isolation of cosmid clones by homologous recombination in Escherichia coli.

A procedure for selection of specific cosmid clones by homologous recombination between cosmid clones from a library and sequences cloned into a plasmid has been developed. Cosmid libraries constructed in a rec- host strain are packaged in vivo into lambda particles. Appropriate aliquots are then introduced into a rec+ host containing the sequence used for selection cloned into a plasmid vector without sequence homology to the cosmid vector. After a short time for recombination, the cosmids are packaged in vivo. Cosmids that have taken up the plasmid by homologous recombination are isolated by plating under conditions selecting for the antibiotic resistance markers carried by both vectors. The recombined cosmids can lose the inserted sequence by another homologous recombination event and, after packaging in vivo, these revertants can be identified on appropriate indicator plates.     

Insulin stimulation of Na+-K+ pump in clonal rat osteosarcoma cells

Clonal osteoblast-like cells derived from a rat osteogenic sarcoma (UMR 106-06) were shown to possess specific, high-affinity binding sites for insulin, with a receptor density of 22,000/cell. The hormone, at physiologic concentrations (1-10 ng/ml), was found to stimulate active K+ transport into these cells, the effect being mediated via the Na+-K+ pump. Alterations in insulin-receptor status by treatment of cells with glucocorticoids or exposure to subphysiologic pH was reflected in parallel changes in the sensitivity of the K+-uptake process to the hormone. We conclude that insulin can directly affect the metabolism of bone cells and that the hormone's action on transmembrane ion transport may be linked to interaction with its cell surface receptors.     

The Tuskegee Legacy Project: willingness of minorities to participate in biomedical research

The broad goal of the Tuskegee Legacy Project (TLP) study was to address, and understand, a range of issues related to the recruitment and retention of Blacks and other minorities in biomedical research studies. The specific aim of this analysis was to compare the self-reported willingness of Blacks, Hispanics, and Whites to participate as research subjects in biomedical studies, as measured by the Likelihood of Participation (LOP) Scale and the Guinea Pig Fear Factor (GPFF) Scale. The Tuskegee Legacy Project Questionnaire, a 60 item instrument, was administered to 1,133 adult Blacks, Hispanics, and non-Hispanic Whites in 4 U.S. cities. The findings revealed no difference in self-reported willingness to participate in biomedical research, as measured by the LOP Scale, between Blacks, Hispanics, and Whites, despite Blacks being 1.8 times as likely as Whites to have a higher fear of participation in biomedical research on the GPFF Scale.     

Chronic obstructive pulmonary disease severity and cardiovascular outcomes

Objective: To identify predictors of chronic obstructive pulmonary disease (COPD) severity and assess the relation between COPD severity and risk of cardiovascular outcomes. Study design and setting: A␣cohort of patients with diagnosed and treated COPD was compiled from the Saskatchewan Health longitudinal databases. We used multivariate modeling to identify predictors of hospitalization for COPD as an indicator of COPD severity, and we used the model to characterize patients according to quintiles of COPD severity. These severity levels were used as independent variables in multivariate models of cardiovascular outcomes. Results: Determinants of COPD severity included emphysema, recent nebulizer use, home oxygen services, corticosteroid use, frequent bronchodilator use, pneumonia and prior COPD exacerbation. The 20% of patients with the highest COPD severity were 1.27 (CI: 1.07–1.50) times more likely to have arrhythmia, 1.25 (CI: 1.07–1.46) times more likely to have ischemic heart disease, 1.38 (CI: 1.11–1.71) times more likely to have angina, 2.28 (CI: 1.95–2.66) times more likely to have congestive heart failure, and 1.63 (CI: 1.22–2.16) times more likely to die of cardiovascular causes than the least severe 20% of patients. Conclusions: Patients with more severe COPD, as defined by our model, had higher cardiovascular morbidity and mortality than patients with less severe COPD.     

Untersuchungen über die Hefeflora auf gesunder Haut*

Zusammenfassung: Das Hefevorkommen auf intakter Haut verlangt Beachtung, da die fakulta-tiv pathogenen Hefepilze unter besonderen Bedingungen klinische Bedeutung als Krankheits-erreger erlangen. Durch die genaue mykologische Differenzierung der isolierten Hefestämme, die Ermittlung ihrer Häufigkeit und ihrer speziellen iokalen Verteilung konnten wir die notwen-dige Vergleichsbasis schaffen, die im Fall tatsSchlich entstandener Hefemykosen Aussagen über die pathogene Rolle dieser Pilze ermöglicht. Summary: The occurence of yeasts on healthy skin is of practical importance as some yeasts may become pathogens under special clinical conditions. 651 yeast strains were isolated from 135 persons without skin lesions by taking swabs from 24 different skin regions. 126 strains of the genus Candida and among these only 18 strains of C. albicans were found. The data obtained may serve as a basis for comparison with isolates from yeast mycoses of the skin and thus contribute to our knowledge of the pathogenic role of yeasts.     

Veränderungen im Chromosomensatz heterolog wachsender Tumoren

Zusammenfassung Der Chromosomensatz einer Walker-Carcinom-Linie, welche auf Ratten, Mäusen und Goldhamstern wächst, wurde untersucht. Die Morphologie der Chromosomen und ihre Zahl ist auf allen drei Tierarten in dieser Tumorlinie gleich. Ein auftretendes submetazentrisches Marker-Chromosom mit heterochromatischem Abschnitt findet sich in gleich hohem Prozentsatz in Tumor-zellen aller drei Tierarten.

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Summary The chromosome-sets of a Walker carcinoma line were studied while growing in rats, mice, and gold hamsters. The morphology of the chromosomes and their number for this tumor-line were the same in all three types of animals. A submetacentric marker-chromosome appearing with heterochromatic segments was found in the same high percentage in the tumor cells of all three types of animal.

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Der Deutschen Forschungsgemeinschaft danken wir für die Unterstützung bei Durchführung der Arbeit.     

The where, what and why of the developing renal stroma

In recent years, a great deal has been learnt about the molecular regulation of kidney development. While most research has focused on the molecular regulation of ureteric branching morphogenesis and nephron formation, significant insights into the definition and functions of the renal stroma have emerged. Many molecules expressed in the developing renal stroma are now known to play significant regulatory roles in kidney development. However, the term 'renal stroma' continues to have different meanings to different researchers. This review clarifies this situation and defines the derivation, location and functions of the stroma in the developing metanephros.