Nitric oxide (NO) plays an important role as a cell-signalling molecule, anti-infective agent and, as most recently recognised, an antioxidant. The metabolic fate of NO gives rise to a further series of compounds, collectively known as the reactive nitrogen species (RNS), which possess their own unique characteristics. In this review we discuss this emerging aspect of the NO field in the context of the formation of the RNS and what is known about their effects on biological systems. While much of the insight into the RNS has been gained from the extensive chemical characterisation of these species, to reveal biological consequences this approach must be complemented by direct measures of physiological function. Although we do not know the consequences of many of the dominant chemical reactions of RNS an intriguing aspect is now emerging. This review will illustrate how, when specificity and amplification through cell signalling mechanisms are taken into account, the less significant reactions, in terms of yield or rates, can explain many of the biological responses of exposure of cells or physiological systems to RNS.

All tissues contain the enzymes that modify and remove O-GlcNAc dynamically from nucleocytoplasmic proteins. These enzymes have been shown to play a role in the control of transcription, vesicular trafficking and, more recently, proteasome function. Modification by O-GlcNAc of the 19S cap of the proteasome inhibits proteasomal function. Transcripts of both O-GlcNAc transferase and O-GlcNAcase are very abundant in the brain, with the highest concentrations in hippocampal neurons and Purkinje cells. When the on-rate of modification is favored over the off-rate by intraventricular administration of a drug, streptozocin, these areas of the brain display the most rapid accumulation of O-GlcNAc. Cerebral proteasome function is reduced and ubiquitin and p53 accumulate in these brain regions, with the subsequent activation of a p53-dependent transgene and the endogenous Mdm2 gene. Later, some hippocampal cells, but not Purkinje cells, undergo apoptosis. These observations suggest that the OGlcNAc system may participate in neurodegeneration, particularly in the hippocampus.

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As part of an effort to develop detectors for selected species of bacterial spores, we screened phage display peptide libraries for 7-and 12-mer peptides that bind tightly to spores of Bacillus subtilis. All of the peptides isolated contained the sequence Asn-His-Phe-Leu at the amino terminus and exhibited clear preferences for other amino acids, especially Pro, at positions 5 to 7. We demonstrated that the sequence Asn-His-Phe-Leu-Pro (but not Asn-His-Phe-Leu) was sufficient for tight spore binding. We observed equal 7-mer peptide binding to spores of B. subtilis and its most closely related species, Bacillus amyloliquefaciens, and slightly weaker binding to spores of the closely related species Bacillus globigii. These three species comprise one branch on the Bacillus phylogenetic tree. We did not detect peptide binding to spores of several Bacillus species located on adjacent and nearby branches of the phylogenetic tree nor to vegetative cells of B. subtilis. The sequence Asn-His-PheLeu-Pro was used to identify B. subtilis proteins that may employ this peptide for docking to the outer surface of the forespore during spore coat assembly and/or maturation. One such protein, SpsC, appears to be involved in the synthesis of polysaccharide on the spore coat. SpsC contains the Asn-His-Phe-Leu-Pro sequence at positions 6 to 10, and the first five residues of SpsC apparently must be removed to allow spore binding. Finally, we discuss the use of peptide ligands for bacterial detection and the use of short peptide sequences for targeting proteins during spore formation.A limited number of bacteria produce endospores (or spores) upon nutrient deprivation of vegetatively growing cells. The spore is dormant and highly resistant to extreme temperatures, radiation, desiccation, harsh chemicals, and physical damage. These properties allow spores to survive adverse environments-for many years in some cases-until encountering conditions that trigger germination and vegetative cell outgrowth (17). The genus Bacillus includes a diverse collection of gram-positive, rod-shaped, aerobic, spore-forming soil bacteria (20). In these bacteria, the sporulation process begins with a final round of DNA replication followed by an asymmetric septation that produces large and small genome-containing compartments: the mother cell and prespore, respectively (7). The mother cell septal membrane migrates around the prespore, surrounding it with two opposing membranes. Between these membranes, the prespore, now called the forespore, is encircled first by a thin germ cell wall and then by a thick layer of modified peptidoglycan, the cortex (8). Multiple layers of a proteinaceous spore coat are then deposited onto the cortex. In the well-studied case of Bacillus subtilis, the coat layers (i.e., under, inner, and outer coats) are composed of over two dozen different proteins (6, 12). For B. subtilis, the outer coat may be tightly covered by a thin and presently poorly characterized surface-exposed layer (25,26). For other Bacillus species (e.g., B. ...

The PRL-secreting cells of the pituitary gland normally express transforming growth factor-alpha (TGF alpha). To determine the effect of increasing TGF alpha expression in the pituitary, a transgenic mouse model was created in which overexpression of human TGF alpha was directed to the pituitary lactotrophs using the rat PRL promoter. Of the four gene-positive mouse lines, two expressed the messenger RNA corresponding to the transgenic in the pituitary glands. However, in both these lines, expression could only be detected in the female animals. Expression of the transgenic could be detected as early as 1 month of age, but no pathology or developmental abnormalities were detected until the animals reached 6 months, at which time, hyperplasia of the lactotrophs. By the age of 12 months, all of the homozygous transgenic females had developed pituitary adenomas that were immunopositive for PRL. The other hormone-producing cells of the pituitary showed no obvious pathology. The male transgenics developed neither hyperplasia nor adenomas, nor did the gene-positive transgenic lines that did not express the transgene. In no case was an aggressive pituitary tumor seen. This transgenic mouse model indicates that TGF alpha overexpression by lactotrophs stimulates the growth of these pituitary cells. Furthermore, TGF alpha has a highly localized action in the pituitary gland, resulting only in lactotroph hyperplasia and prolactinomas. These observations suggest that TGF alpha might play a role in the development of prolactinomas.

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The effects of alpha-chloralose on the micturition reflex were evaluated using an efficiently voiding decerebrate cat model. At laparotomy cannulas were introduced into the urethra and/or bladder for measurement of urethral perfusion pressure and/or bladder pressure during bladder filling and voiding. After establishment of efficient voiding in the anesthetic-free decerebrate cat, chloralose, 50 mg/kg iv, was administered. Parameters assessed before and after anesthetic included bladder pressure at peak of contraction (voiding pressure), intravesical pressure at onset of bladder contraction (threshold pressure), contraction amplitude, duration of bladder contraction, bladder volume at onset of bladder contraction (volume threshold), and residual bladder volume after voiding (postvoid residual). In addition to these parameters, preparations with intact bladder-urethra and with divided bladder-urethra were used to assess effects of chloralose on voiding efficiency and coordination between bladder and urethra, respectively. Chloralose significantly reduced voiding pressure, contraction amplitude, and voiding efficiency. Neither vehicle for the chloralose nor sympathetic denervation of the lower urinary tract affected these reductions. Chloralose had no effect on direct contraction of the bladder and urethra produced by intra-arterial acetylcholine (25-100 micrograms). Chloralose converted the synergic bladder and urethral responses during voiding to dyssynergic responses. Neuromuscular blockade with gallamine, 10 mg/kg iv, improved voiding efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

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