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Neuronal nitric oxide (NO) synthase, localized to human chromosome 12, uniquely participates in diverse biologic processes; neurotransmission, the regulation of body fluid homeostasis, neuroendocrine physiology, control of smooth muscle motility, sexual function, and myocyte/myoblast biology, among others. Restriction enzyme mapping, subcloning, and DNA sequence analysis of bacteriophage- and yeast artificial chromosome-derived human genomic DNA indicated that the mRNA for neuronal NO synthase is dispersed over a minimum of 160 kilobases of human genomic DNA. Analysis of intron-exon splice junctions predicted that the open reading frame is encoded by 28 exons, with translation initiation and termination in exon 2 and exon 29, respectively. Determination of transcription initiation sites in brain poly(A) RNA with primer extension analysis and RNase protection revealed a major start site 28 nucleotides downstream from a TATA box. Sequence inspection of 5'-flanking regions revealed potential cis-acting DNA elements: AP-2, TEF-1/MCBF, CREB/ATF/c-Fos, NRF-1, Ets, NF-1, and NF-kappa B-like sequences. Diversity appears to represent a major theme apparent upon analysis of human neuronal NO synthase mRNA transcripts. A microsatellite of the dinucleotide variety was detected within the 3'-untranslated region of exon 29. Multiple alleles were evident in normal individuals indicating the existence of allelic mRNA sequence variation. Characterization of variant human neuronal NO synthase cDNAs indicated the existence of casette exon 9/10 and exon 10 deletions as examples of structural mRNA diversity due to alternative splicing. The latter deletion of a 175-nucleotide exon introduces a frame-shift and premature stop codon indicating the potential existence of a novel NH2 terminus protein. In summary, analysis of the human neuronal NO synthase locus reveals a complex genomic organization and mRNA diversity that is both allelic and structural.

Susceptibility testing of 1,688 Haemophilus influenzae isolates found 484 ampicillin-resistant strains; 474 strains (28.4%) were beta-lactamase positive, and 5 strains (0.4%) were non-beta-lactamase producers. Restriction enzyme digestion of the beta-lactamase amplicon determined that, of 157 strains, 11 (7.0%) contained ROB-1 beta-lactamase and 146 (93.0%) contained a TEM-type beta-lactamase.

Fifty-five patients with cytomegalovirus (CMV)-associated neonatal hepatitis (NH) were followed for 12 to 90 months. Six patients (10.9%) died from either a fulminant course or a chronic liver disease. Among the remaining 49 patients, whose liver function was completely recovered, there were eight with retardation of developmental or growth status, and two with hearing impairment. Overall, 20.4% of the survivors suffered from a long-term impact. The unfavorable outcome was related to several clinical and pathological parameters. These included persistence of clay-colored stool, presence of splenomegaly, ascites or anemia, high peak total and direct bilirubin, low nadir albumin levels, diffuse giant cell transformation and cirrhosis of the liver. The seropositivity of CMV infection did not significantly correlate with the outcome.

Recurrent chromosomal abnormalities in retinoblastomas involve numbers 13, 1, and 6, as well as homogeneously staining regions (HSR) and double minutes (DMS). Evidence suggesting that chromosome 13 contains a gene responsible for tumorigenesis has already been presented. We postulate that the genetic changes resulting from abnormalities of chromosomes 1 and 6 and the HSR/DMS provide a selective growth advantage to cells in which they occur. Support for this hypothesis, as it relates to the HSR/DMS and oncogene amplification, is discussed.

The early embryonic development of hemopoietic cells in Xenopus laevis was examined. Either dorsal lateral plate (DLP) or ventral blood island (VBI) mesoderm was reciprocally transplanted between cytogenetically distinct (2N or 3N) stage 14 to 19 (neural fold) embryos. F-DNA content of circulating erythrocytes was assayed at stages 40, 41, 43, 45, and 49. The F-DNA content of cells in the thymus and mesonephros was assayed at stage 49. F-DNA values were used to distinguish between donor or host origin of hemopoietic cells in individual animals. The results demonstrated that DLP mesoderm gave rise to a population of stem cells that colonized the thymus and mesonephros, but not the blood. VBI mesoderm gave rise to a population of stem cells that colonized the blood and thymus, but not the mesonephros. These experiments show that there are two stem cell compartments in the amphibian embryo, separated in both space and time.

Intraperitoneal administration of prostaglandin E1 (PGE1) produced a hypothermia in rats at room temperature (22°C). The hypothermia in response to PGE1 was due to cutaneous vasodilatation and decreased metabolic heat production. Depletion of brain 5-hydroxytryptamine (with 5,6-dihydroxytryptamine and p-chlorophenylalanine) did not alter the PGE1-induced hypothermia. However, depletion of brain catecholamines (with 6-hydroxydopamine) and blockade of central catecholaminergic receptors (with phentolamine and propranolol) both greatly reduced the PGE1-induced hypothermia. The data indicate that PGE1 lowers body temperature in rats by acting on the central catecholaminergic systems.

The early embryonic development of hemopoietic cells in Xenopus laevis was examined. Either dorsal lateral plate (DLP) or ventral blood island (VBI) mesoderm was reciprocally transplanted between cytogenetically distinct (2N or 3N) stage 14 to 19 (neural fold) embryos. F-DNA content of circulating erythrocytes was assayed at stages 40, 41, 43, 45, and 49. The F-DNA content of cells in the thymus and mesonephros was assayed at stage 49. F-DNA values were used to distinguish between donor or host origin of hemopoietic cells in individual animals. The results demonstrated that DLP mesoderm gave rise to a population of stem cells that colonized the thymus and mesonephros, but not the blood. VBI mesoderm gave rise to a population of stem cells that colonized the blood and thymus, but not the mesonephros. These experiments show that there are two stem cell compartments in the amphibian embryo, separated in both space and time.