Geometric criteria of hydrogen bonds in proteins and identification of `bifurcated' hydrogen bonds

Empirical criteria for identification of hydrogen bonds wereanalyzed to produce a set of geometrically consistent criteria.For a data set of 30 structures, application of a set of purelygeometrical criteria, along with exclusion of abnormal backboneconformations, also excluded a common interaction of Ser/Thrside chains with Asp/Glu side chains ([ST]/[DE] pairs). Theseinteractions were termed `bifurcated hydrogen bonds/', whichimplies delocalization of a positively charged hydrogen of hydroxylbetween the two acceptor atoms of the carboxylic group. These`bifurcated/' interactions are among the most common packingpatterns for [ST]/[DE] pairs of side chains. Therefore, theidentification of hydrogen bonds cannot be based on geometricalcriteria only and requires introduction of some physico-chemicalcriteria.     

Expression, exon-intron organization, and chromosome mapping of the human sodium iodide symporter

The active iodide uptake of the thyroid gland in humans is mediated by the human sodium iodide symporter (hNIS). In this report, we show that hNIS expression was detected primarily in thyroid tissue, but also in breast, colon, and ovary tissues. Expression of hNIS is greatly reduced in thyroid tumors compared to normal thyroid tissue. Among tumor tissues, hNIS expression appears to be variable, consistent with the variable response to radioiodide treatment observed for thyroid carcinomas. The coding region of hNIS is interrupted by 14 introns, and the nucleotide sequence of each exon-intron junction is reported. Using this information, an alternatively spliced form of hNIS was identified. Finally, the chromosome location of the hNIS gene was mapped to chromosome 19p.     

Distal dorsal forearm flap

Reinstatement and spontaneous recovery of previously extinguished nicotine-taking behavior were examined in rats. Male subjects were trained to self-administer nicotine (30 microg/kg per infusion, IV; one 60-min session per day for 3 weeks). Extinction sessions were then given for 5-10 days during which saline was substituted for nicotine. Subsequently, in the first set of tests for nicotine seeking, the reinstatement of lever presses that previously delivered nicotine was examined after priming injections of saline and nicotine (75, 150 and 300 microg/kg, SC; and 30 and 60 microg/kg, IV). In the second set of tests for nicotine-seeking, rats were tested after an additional 21-day drug-free period during which they were not exposed to the self-administration chambers (a test for the spontaneous recovery of drug seeking), and after priming injections of nicotine (150 and 300 microg/kg, SC). Reinstatement of extinguished food-reinforced behavior after exposure to nicotine was also determined. Priming injections of nicotine reinstated nicotine seeking regardless of the route of administration. In addition, previously extinguished nicotine seeking recovered spontaneously after a 21-day period during which rats were not exposed to the drug-taking environment. Nicotine also reinstated extinguished food-reinforced behavior in rats with a history of nicotine self-administration, but not in drug-naive rats. The present results extend previous work with opioid and stimulant drugs on reinstatement of drug seeking by the self-administered drug. It also appears that, as with other positive reinforcers, the mere passage of time is a sufficient condition for the spontaneous recovery of extinguished nicotine seeking.     

Speeding up protein folding: mutations that increase the rate at which Rop folds and unfolds by over four orders of magnitude

The proteasome is a multi-subunit protease responsible for the production of peptides presented by major histocompatibility complex class I molecules. Accumulated evidence indicates that, upon stimulation with interferon-gamma (IFN-gamma), three beta-type subunits, designated LMP2, LMP7, and PSMB10, are incorporated into the 20S proteasome by displacing the housekeeping beta-type subunits designated PSMB6, PSMB5, and PSMB7, respectively. These changes in the subunit composition appear to facilitate class I-mediated antigen presentation, presumably by altering the cleavage specificities of the proteasome. In the present study, we determined the organization of the mouse gene Psmb5, coding for the PSMB5 subunit. Psmb5 is made up of three exons, spanning approximately 5 kilobases. Its exon-intron organization differs radically from those of the other IFN-gamma-regulated, beta-type subunit genes including Lmp7 with which Psmb5 is believed to share an immediate common ancestor. The structure of the mouse Psmb5 gene is identical to that of its recently characterized human counterpart. Thus, the unique organization of the gene coding for the PSMB5 subunit appears to have been established before mammalian radiation. As well as the Psmb5 gene, the mouse genome contains a processed pseudogene designated Psmb5-ps. Interspecific backcross mapping showed that Psmb5 maps close to the Gtrgal2 locus on chromosome 14 and that Psmb5-ps is located in the vicinity of the Psme3 locus on chromosome 11. These results were confirmed by fluorescent in situ hybridization analysis that localized Psmb5 to band C2 to proximal D1 of chromosome 14 and Psmb5-ps to band D of chromosome 11.     

A standardized method for CMOS unit process development

The multipurpose mask set described, which consists of three stepper reticles, contains 95% of all test structures required for CMOS process development and random defect detection, thereby dramatically reducing the stepper reticle inventory and the frequency of reticle changes. Realizing the mask set by two dozen standard unit processes minimizes the feedback loop for defect density data, parametric data and unit process data     

Ochratoxin A in pork kidneys--description of a method

A rapid procedure for the isolation and clean-up on a silica gel column is described for the determination of Ochratoxin A from pork kidneys. The detection limit is 0.3 microgram/kg.     

Hearing loss after spinal anesthesia. An audiological controlled trial

Audiological tests were conducted on 34 patients before and after undergoing an operation in spinal anaesthesia. One of these patients developed a considerable unilateral hearing loss in the low-frequency range, which persisted until an epidural blood-patch was given. Unexpectedly, we also found a general small but significant threshold shift at 500 Hz, which has never before been described in the literature. The biological mechanism is discussed, and the results suggest that the explanation of the hearing loss could be a condition similar to endolymphatic hydrops, resulting from perilymphatic hypotension due to loss of liquor during and after the spinal anaesthesia.