Regulation and regulatory role of gamma-carboxyglutamic acid containing clotting factors

Several investigators have recently reported that significant numbers of appropriately adapted mutants can be induced in bacterial and yeast strains by exposing stationary phase cells to specific environmental challenges. The resulting mutants are said to be both selection-induced and demonstrably non-random in origin; if this interpretation is correct, it is in direct conflict with the conventional neo-Darwinian view, which is that spontaneous mutants are truly random in origin and arise without the intervention of any overtly adaptive forces. We believe that there are alternative ways of accounting for the appearance of many (and probably all) of the additional mutants which proponents of the adaptive mutation theory claim are observed only after they applied the appropriate selective pressure. Having reviewed the available evidence, we consider that most (if not all) of the sorts of mutants which are said to have been induced following exposure of stationary-phase cells to intense selective pressure are equally likely to have been generated during the operation of certain well-known, conventional (and essentially random) cellular DNA repair processes. Evidence in support of our view can be found in the mainstream literature on the origins of spontaneous mutations. We also note that some of the molecular models which have recently been proposed to explain the production of selection-induced mutations preferentially (or even only) in genes of adaptive significance may turn out to be of considerable interest in their own right, even although the mutants whose origins they were intended to explain may turn out to have arisen in a manner which is totally independent of the conditions used for their selection.     

Individual differences in arousal and accessibility to information in memory

The authors conducted 9 experiments to test the hypothesis (S. Schwartz, 1975) that arousal influences the accessibility of information stored in memory. They investigated the relationship between arousal levels (as indexed by personality types) and the type of stimuli or cues presented during study or test. They predicted that low-arousal individuals (stable extraverted individuals in Experiments 1-3 and 5-9 and high-impulsive individuals in Experiment 4) would be influenced by semantic stimuli, whereas high-arousal individuals (neurotic introverted individuals in Experiments 1-3 and 5-9 and low-impulsive individuals in Experiment 4) would be influenced by physical (i.e., graphic, phonetic, or both) stimuli. They tested the arousal-accessibility hypothesis by using a variety of tasks including verbal discrimination, false recognition, cued recall, and paired associates. With the exception of the finding that stable extraverted participants performed better than neurotic introverted participants on an incidental associative-matching task (Experiment 3), the results from the verbal discrimination studies (1-5) did not support the hypothesis. In Experiment 6, the authors tested the hypothesis by using a false-recognition task. False alarms varied as a function of phonetic and semantic stimuli, but personality types were not differentially sensitive to the manipulation. The same was true for the cued-recall studies (Experiments 7 and 8); personality types were not differentially sensitive to the semantic and phonetic stimuli. Experiment 9 (paired-associate learning) was a replication of Schwartz's study. The authors found some support for the Schwartz hypothesis: Extraverted participants were adversely affected by semantic similarity. Overall, the findings did not provide much support for the arousal-accessibility hypothesis.     

Renal resistive index in experimental partial and complete ureteral obstruction

RATIONALE AND OBJECTIVES: Recent clinical work suggests that the Doppler resistive index (RI) may be useful in distinguishing obstructive from nonobstructive hydronephrosis. We evaluated the usefulness of the RI in a rabbit model of hydronephrosis. METHODS: Unilateral partial ureteral obstruction was produced in nine rabbits and complete obstruction in another nine. Three sham operations were performed, and these animals served as control subjects. The RI was measured in all kidneys before and 6 hr after surgery and on days 1, 4, and 7 postoperatively. The RI and the difference in RI (delta RI) between the obstructed and normal kidney were evaluated over time using a two-way analysis of variance. The intravenous urography and Whitaker tests served as gold standards. RESULTS: Hydronephrosis was observed on sonograms in all obstructed kidneys. Comparing groups, there was no significant difference in mean RI or delta RI between the three groups at any time point. Looking at individual groups over time, there was no significant change in mean delta RI, whereas the change in mean RI was significantly elevated above baseline only in the complete obstruction group at 6 hr (p = .002) and on days 4 (p = .008) and 7 (p = .006). In evaluating varying thresholds of RI and delta RI, we could not consistently discriminate between normal and obstructed kidneys. CONCLUSION: Although complete obstruction caused a significant increase in RI, partial obstruction failed to do so. RI and delta RI values proved to be insensitive predictors of obstruction in this rabbit model.     

Admission to an intensive care unit after transvenous implantable cardioverter defibrillator implantation: analysis of risk factors

The endocrine abnormality that causes slipped capital femoral epiphysis (SCFE) has not been revealed. Recent studies have shown that parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH)2D] are involved in growth-plate chondrogenesis and matrix mineralization. Thus we examined in 13 patients with SCFE the serum levels of three immunoreactive forms of PTH (iPTH): the whole peptide [(1-84)PTH], the fragment containing the COOH-terminal portion (C-PTH), and the midportion (M-PTH). Additionally, serum levels of 25-hydroxyvitamin D [25-(OH)D] and 1,25-(OH)2D were measured. We found that the levels of M-PTH were significantly lower than those of controls, whereas levels of C-PTH and (1-84)PTH were not significantly different from those of controls. Similarly, levels of 1,25-(OH)2D were also significantly lower than control levels. In patients with initially low levels of M-PTH and 1,25-(OH)2D in whom the levels were monitored over a period, all levels returned to normal within a year after the onset of disease. The deficiency of M-PTH or 1,25-(OH)2D during the growth spurt could result in SCFE, although in this study, we cannot deny the possibility that the slippage may cause the deficiency.     

NASBA technology: isothermal RNA amplification in qualitative and quantitative diagnostics

The phosphorylation state of neurofilaments plays an important role in the control of cytoskeletal integrity, axonal transport, and axon diameter. Immunocytochemical analyses of spinal cord revealed axonal localization of all protein phosphatase subunits. To determine whether protein phosphatases associate with axonal neurofilaments, neurofilament proteins were isolated from bovine spinal cord white matter by gel filtration. approximately 15% of the total phosphorylase a phosphatase activity was present in the neurofilament fraction. The catalytic subunits of PP1 and PP2A, as well as the A and B alpha regulatory subunits of PP2A, were detected in the neurofilament fraction by immunoblotting, whereas PP2B and PP2C were found exclusively in the low molecular weight soluble fractions. PP1 and PP2A subunits could be partially dissociated from neurofilaments by high salt but not by phosphatase inhibitors, indicating that the interaction does not involve the catalytic site. In both neurofilament and soluble fractions, 75% of the phosphatase activity towards exogenous phosphorylase a could be attributed to PP2A, and the remainder to PP1 as shown with specific inhibitors. Neurofilament proteins were phosphorylated in vitro by associated protein kinases which appeared to include protein kinase A, calcium/calmodulin-dependent protein kinase, and heparin-sensitive and -insensitive cofactor-independent kinases. Dephosphorylation of phosphorylated neurofilament subunits was mainly (60%) catalyzed by associated PP2A, with PP1 contributing minor activity (10-20%). These studies suggest that neurofilament-associated PP1 and PP2A play an important role in the regulation of neurofilament phosphorylation.     

Evaluation of the AnaeroPack system for growth of anaerobic bacteria

Growth of anaerobic bacteria in the AnaeroPack (Mitsubishi Gas Chemical America, Inc., New York, N.Y.) anaerobic atmosphere generation systems, both the AnaeroPack jar and pouch and the AnaeroPack in a GasPak jar were considered equivalent to or better than growth obtained in the corresponding GasPak jar or pouch system (Becton Dickinson Microbiology Systems, Cockeysville, Md.) for 89 (86%) of the 103 anaerobes tested. There were a total of 26 discrepancies after 48 h of incubation, with 16 discrepancies unresolved after 96 h of incubation. The AnaeroPack jar and pouch never failed to reduce the anaerobic indicator. The AnaeroPack systems are easy to use and performed at least as well as or better than the BBL GasPak systems for growth of anaerobic bacteria.     

Response of coronary microvascular collaterals to activation of ATP-sensitive K+ channels

The feasibility of intragenerically characterizing bifidobacteria by a comparison of a short region within the recA gene was tested. An approximately 300 bp fragment of the recA gene was PCR-amplified from six species from the genus Bifidobacterium using primers directed to two universally conserved regions of the recA gene. A phylogenetic analysis of the sequenced recA products compared favorably to classification based on the 16S rRNA sequences of the species tested. To apply this rapid methodology to unknown human intestinal bifidobacteria, 46 isolates were randomly chosen from the feces of four subjects and initially characterized by RFLP analysis of a PCR-amplified region of their 16S RNA genes. From a representative of the dominant RFLP family in each of the subjects, the recA segment was PCR-amplified, sequenced and phylogenetically analyzed. All four isolates were found to be related to one another and to B. longum and B. infantis. These results illustrate that the recA gene may be useful for intrageneric phylogenetic analysis as well as for the identification of unknown fecal bifidobacteria.     

Racial differences in Helicobacter pylori seroprevalence in Singapore: correlation with differences in peptic ulcer frequency

The aim of this study was to determine, first, whether racial differences exist in the seroprevalence of Helicobacter pylori infection in Singapore, and second, whether these differences correlate with racial differences in peptic ulcer frequency. A commercial serological test for immunoglobulin (Ig)G antibody to H. pylori which was 90% sensitive and 83% specific in our population was used to screen 403 adult blood donors of Chinese, Malay and Indian origin, aged between 15-60 years. Serum specimens from 84 paediatric patients admitted to the Paediatrics Department, National University of Singapore, with non-gastroenterological illnesses were also tested. In all three races, seroprevalence of H. pylori increased with age. Indians have the highest prevalence of infection followed by Chinese and Malays. Peptic ulcer prevalences are known to be highest in Chinese, followed by Indians and Malays. The Malays have the lowest prevalence of H. pylori and peptic ulcer among the three races in Singapore. Indians have a higher prevalence of H. pylori antibodies but a lower frequency of peptic ulcer than the Chinese. Racial differences in peptic ulcer frequency between Chinese and Indians are not explained by the prevalence of H. pylori infection; other environmental or genetic factors may be involved.