Electro and acoustic myography for noninvasive assessment of lumbar paraspinal muscle function

In 31 normal subjects (17 male), aged 19-48 years, and 8 patients with chronic low back pain (4 male), aged 37-55 years, the repeatability of surface recordings of acoustic myography (AMG) and electromyography (EMG) were examined in the lumbar paraspinal muscles. Five isometric test positions were examined. In 21 of the normal subjects, four positions tested were: quiet standing, half extension from prone lying, full extension from prone with and without resistance. In 10 of the normal subjects and the 8 back pain patients, a standardised, unsupported horizontal position with the upper body over the end of a couch was tested. The AMG and EMG signals were full-wave rectified and integrated (iAMG and iEMG). The variability of recordings during repeated 5-s isometric contractions was assessed by analysis of variance (ANOVA) and the coefficient of variation (CV) was calculated from the ANOVA. Both recording techniques produced the most repeatable results during the unsupported, horizontal hold position. In the normal subjects, CV were, iAMG 5.6%, iEMG 4.9%; and in the patients, iAMG 4.4%, iEMG 2.6%. The CV for the other four isometric test positions ranged from 15.3% to 29.4% for iAMG, and 8% to 15.7% for iEMG. These results demonstrated that a controlled test manoeuvre for examining AMG and EMG of the paraspinal muscles was vital for repeatable recordings. The CV for the standardised, horizontal position were lower than for previously published results.(ABSTRACT TRUNCATED AT 250 WORDS)     

The yeast UME6 gene product is required for transcriptional repression mediated by the CAR1 URS1 repressor binding site.

URS1 is known to be a repressor binding site in Saccharomyces cerevisiae that negatively regulates expression of many genes including CAR1 (arginase), several required for sporulation, mating type switching, inositol metabolism, and oxidative carbon metabolism. In addition to the proteins previously shown to directly bind to the URS1 site, we show here that the UME6 gene product is required for URS1 to mediate repression of gene expression in the absence of inducer. We also show that mutations in the CAR80 (CARGRI) gene are allelic to those in UME6.     

Differentially regulated malate synthase genes participate in carbon and nitrogen metabolism of S. cerevisiae.

We have isolated a second gene (MLS1), which in addition to DAL7, encodes malate synthase from S. cerevisiae. Expression of the two genes is specific for their physiological roles in carbon and nitrogen metabolism. Expression of MLS1, which participates in the utilization of non-fermentable carbon sources, is sensitive to carbon catabolite repression, but nearly insensitive to nitrogen catabolite repression. DAL7, which participates in catabolism of the nitrogenous compound allantoin, is insensitive to carbon catabolite repression, but highly sensitive to nitrogen catabolite repression. Results obtained with null mutations in these genes suggest that S. cerevisiae contains at least one and perhaps two additional malate synthase genes.     

Single-strand conformation polymorphism (SSCP) analysis of exon 11 of the CFTR gene reliably detects more than one third of non-ΔF508 mutations in German cystic fibrosis patients

Summary In Central Europe, the F508 deletion accounts for approximately 75% of mutations in the cystic fibrosis transmembrane conductance regulator gene causing cystic fibrosis. The remainder comprise a large number of individually infrequent mutations whose detection requires a disproportionately large effort. However, a sizeable proportion of non-F508 mutations have been found to cluster within exon 11. We have taken advantage of this clustering to detect a total of five previously described point mutations present on 26/72 (36%) non-F508 chromosomes by polymerase chain reaction/direct sequencing of exon 11. These exon 11 mutations were then subjected to single-strand conformation polymorphism (SSCP) analysis, which was shown (i) to discriminate reliably between mutant and wildtype alleles and (ii) to generate reproducible mutation-specific band patterns. This analysis thus represents the first attempt to assess SSCP analysis retrospectively, and serves to illustrate the potential of this screening technique in diagnostic medicine.     

Detection of enterotoxigenic Staphylococcus aureus in dried skimmed milk: use of the polymerase chain reaction for amplification and detection of staphylococcal enterotoxin genes entB and entC1 and the thermonuclease gene nuc

The polymerase chain reaction was used to amplify the staphylococcal enterotoxin B and C genes (entB and entC1) and the staphylococcal nuclease gene (nuc). Two sets of primers ("nested primers") were found to be necessary for the detection of low copy numbers of purified DNA in diluent. These allowed detection of ca. 1 fg of purified target DNA, while 100 pg was required before detection of entB, entC1, and nuc with single primer pairs was possible. With nested primers, enterotoxigenic Staphylococcus aureus cells could be detected in artificially contaminated dried skimmed milk samples at levels of ca. 10(5) CFU ml-1 within 8 h. No cross-reaction was observed between the highly homologous entB and entC1 genes. The method showed total specificity for entC1 when tested against a wide variety of other bacteria.     

Direct observation by X-ray analysis of the tetrahedral "intermediate" of aspartic proteinases.

We report the X-ray analysis at 2.0 A resolution for crystals of the aspartic proteinase endothiapepsin (EC 3.4.23.6) complexed with a potent difluorostatone-containing tripeptide renin inhibitor (CP-81,282). The scissile bond surrogate, an electrophilic ketone, is hydrated in the complex. The pro-(R) (statine-like) hydroxyl of the tetrahedral carbonyl hydrate is hydrogen-bonded to both active-site aspartates 32 and 215 in the position occupied by a water in the native enzyme. The second hydroxyl oxygen of the hydrate is hydrogen-bonded only to the outer oxygen of Asp 32. These experimental data provide a basis for a model of the tetrahedral intermediate in aspartic proteinase-mediated cleavage of the amide bond. This indicates a mechanism in which Asp 32 is the proton donor and Asp 215 carboxylate polarizes a bound water for nucleophilic attack. The mechanism involves a carboxylate (Asp 32) that is stabilized by extensive hydrogen bonding, rather than an oxyanion derivative of the peptide as in serine proteinase catalysis.     

C3 allotypes in pregnancy hypertension and eclampsia

C3 allotyping has been performed on 424 Australian women, 203 with normotensive pregnancies, 161 with hypertensive noneclamptic pregnancies and 60 eclamptic women. The frequency of women heterozygous for 'rare' C3 alleles was 1% in the normotensive women and 3.7% in the hypertensive group. Three out of 25 (12%) of the women with proteinuric hypertension in pregnancy carried 'rare' C3 alleles. This suggested the hypothesis that pre-eclampsia/eclampsia is associated with a higher frequency of rare alleles. The sample of 60 eclamptic women collected to test the hypothesis had no rare alleles, refuting the hypothesis. The frequency of the common (C3F, C3S) alleles did not differ significantly between the three groups. We conclude that there is no evidence for any association between susceptibility to eclampsia and allotypes of the C3 complement component.     

Evaluation of methods for the isolation of plasma membranes displaying guanosine 5'-triphosphate-dependence for the regulation of adenylate cyclase activity: potential application to the study of other guanosine 5'-triphosphate-dependent transduction systems

The GTP-dependence for stimulatory and inhibitory regulation of plasma membrane adenylate cyclase activity was measured in plasma membrane fractions isolated from a variety of cell types (platelets, lymphocytes, PC12 cells, GH3 cells, NBP2 cells, and hepatocytes). This report shows that the isolation of plasma membranes for the study of GTP-dependent adenylate cyclase activity was, for some cells, enhanced by the exposure of the cells to glycerol prior to cell lysis. The isolation of plasma membranes from other cells, which did not appear to be sensitive to glycerol pretreatment, was enhanced by the removal of heavy particulate matter prior to fractionation of the cell lysate. The regulation of enzyme activity by various agents was found to be dependent upon the presence of (exogenous) GTP to varying degrees, indicating variable contamination of membrane preparations with GTP. It is concluded that (i) exposure of platelets and lymphocytes to glycerol prior to cell lysis decreases subsequent contamination of the plasma membrane preparation with GTP, and (ii) although glycerol pretreatment of other cells does not ensure the subsequent isolation of plasma membrane adenylate cyclase activity displaying high requirements for (exogenous) GTP, it is a reasonable first approach to be used during the development of procedures for the isolation of plasma membranes.