D10S20, a previously unmapped RFLP (OS-3), is located on 10q near D10S4

The locus recognized by the probe OS-3 is assigned to chromosome 10 both by Southern blot analysis of a panel of somatic cell hybrid DNAs and by genetic linkage to markers already assigned to chromosome 10. In Caucasians this probe recognizes a three-allele TaqI RFLP as well as two-allele BanII and RsaI RFLPs which are both in strong linkage disequilibrium with each other and with the TaqI RFLP. The D10S20 locus defined by this probe maps 5.5 cM distal to D10S4 on the long arm of chromosome 10. Because this human clone hybridizes with mouse genomic DNA, it will be useful in comparative mapping studies.

Suppression of delayed-type hypersensitivity in mice pretreated with diethylstilbesterol: involvement of sex hormones in immunomodulation

Delayed-type hypersensitivity (DTH) responses were suppressed in female mice treated with diethylstilbesterol (DES), a synthetic nonsteroidal compound possessing estrogenic activity, but not in male mice. Upon analysis of this DTH-suppression in DES-treated female mice by use of the macrophage migration inhibition (MI) assay, an in vitro correlate of DTH, suppressor adherent cells (i.e., macrophages) in the peritoneal cavity were found to play an important role in this DTH suppression. On the other hand, DES-induced suppression was observed in surgically castrated male mice with depressed plasma testosterone (TS) levels, but not in TS-treated female mice or in castrated male mice, which suggests that TS inhibited the DES suppression. These results provide evidence that DTH response may be modulated by sex hormones.

Chang-Ning epidemiological study of children's health: I: Passive smoking and children's respiratory diseases

The effects of household exposure to cigarette smoke on hospitalization and incidence of respiratory illness were examined among 2227 children at Chang-Ning District, Shanghai Municipality, People's Republic of China. The passive smoking quantity was estimated by total daily cigarette consumption of family members and number of cigarettes smoked in the home. No mothers who smoked were found. A significant dose-response relationship of passive smoking to hospitalization for respiratory illness during the children's first 18 months of life was found, for which no confounding factors were discovered. The incidence density ratio of hospitalization for respiratory illness was 2.1 for children living in families including people who smoked 20 or more cigarettes a day compared with those living in non-smoking families. The children appeared to be more vulnerable in the first six months of life than in the 7-18 month period, and those with lower birth weight and the artificially fed were more susceptible. The cumulative incidence of bronchitis or pneumonia increased significantly with increasing cigarette smoking of family members, which persisted when sex, birthweight, nursery care, father's education, coal for cooking, and adult cases with chronic respiratory disease were taken into account. Family smoking status was not found to be significantly associated with the incidence of asthma, whooping cough, sinusitis and measles.

Metabolic products of microorganisms. 243. Pyridazomycin, a new antifungal antibiotic produced by Streptomyces violaceoniger

Pyridazomycin, a new antifungal antibiotic produced by Streptomyces violaceoniger sp. griseofuscus (strain Tü 2557), was detected in a selective screening against Mucor hiemalis (Tü 179/180). The amino acid side chain of 1 can be seen as L-ornithine, whose gamma-nitrogen atom is part of a pyridazine ring building a quaternary ammonium system. The structure of 1 was established by spectroscopic analysis of the parent compound and degradation products. The occurrence of a pyridazine ring in microbial secondary metabolites is unique.

Induction of barley leaf urease

Foliar urea application on barley plants increased leaf urease activity for 5 hours with a peak of 20-fold at 2 hours. To discern the mode of urease induction, urea with or without inhibitors and [(35)S]methionine were incubated with leaf sections for different lengths of time. Urease was extracted, partially purified, electrophoresed, and then quantified by fluorogram. Five urease (U) isozymes were separated by PAGE. U(a) and U(b) might be polymers or complexes that occurred only at the peak of induced activity. U(1) and U(2) appeared at 0.5 and 0.75 hour, respectively, after urea induction, peaked at 2 hours, and persisted only in treated leaves for several additional hours indicating that they are transient inducible forms. U(3) was the constitutive form present in control and treated leaves. Induction with cordycepin or cycloheximide completely prevented urea stimulated activity and nullified the existence of isozymes U(a), U(b), U(1), and U(2). (35)S-U(1), which was labeled in the last hour of induction, appeared on fluorogram 1 hour after induction, peaked at 2 hours, and declined at 3 hours. Results indicated that de novo synthesis of urease is activated by the influx of urea.