Response to Rimiterol and Salbutamol Aerosols Administered by Intermittent Positive-pressure Ventilation

The bronchodilator and cardiac effects produced by aerosols of 0·5% salbutamol and 0·5% and 1% rimiterol administered for three minutes in 40% oxygen by intermittent positive-pressure ventilation (I.P.P.V.) were compared in 15 asthmatic patients. Salbutamol and both the concentrations of rimiterol were equipotent in peak bronchodilator effect, but salbutamol had a significantly longer duration of bronchodilator action. There was significantly less increase in heart rate after rimiterol than after salbutamol. Aerosols of 0·5% rimiterol, 0·5% salbutamol, and saline were administered by I.P.P.V. to 10 normal volunteers. There was no difference between the mean heart rates after 0·5% rimiterol and saline but a highly significant increase in mean heart rate was observed after 0·5% salbutamol. It was concluded that 0·5% rimiterol was an effective short-acting bronchodilator drug with little or no cardiac beta₁-adrenergic activity when administered for three minutes by I.P.P.V. in 40% oxygen.     

On the inhibition of muscle membrane chloride conductance by aromatic carboxylic acids

25 aromatic carboxylic acids which are analogs of benzoic acid were tested in the rat diaphragm preparation for effects on chloride conductance (G(Cl)). Of the 25, 19 were shown to reduce membrane G(Cl) with little effect on other membrane parameters, although their apparent K(i) varied widely. This inhibition was reversible if exposure times were not prolonged. The most effective analog studied was anthracene-9-COOH (9-AC; K(i) = 1.1 x 10(-5) M). Active analogs produced concentration-dependent inhibition of a type consistent with interaction at a single site or group of sites having similar binding affinities, although a correlation could also be shown between lipophilicity and K(i). Structure-activity analysis indicated that hydrophobic ring substitution usually increased inhibitory activity while para polar substitutions reduced effectiveness.

These compounds do not appear to inhibit G(Cl) by altering membrane surface charge and the inhibition produced is not voltage dependent. Qualitative characteristics of the I-V relationship for Cl(-) current are not altered. Conductance to all anions is not uniformly altered by these acids as would be expected from steric occlusion of a common channel. Concentrations of 9-AC reducing G(Cl) by more than 90 percent resulted in slight augmentation of G(I). The complete conductance sequence obtained at high levels of 9-AC was the reverse of that obtained under control conditions. Permeability sequences underwent progressive changes with increasing 9-AC concentration and ultimately inverted at high levels of the analog. Aromatic carboxylic acids appear to inhibit G(Cl) by binding to a specific intramembrane site and altering the selectivity sequence of the membrane anion channel.

     

Discrimination of pathogenic clinical isolates and laboratory strains of Bacillus cereus by NMR-based metabolomic profiling

Six different Bacillus cereus strains were selected from two different ecotypes: (1) three commonly used laboratory strains that are considered avirulent, and (2) three clinical isolates from meningitis patients. Screening of genomic DNA for the presence of genes encoding known toxins gave no candidate genes that were unambiguously able to distinguish between the two groups. However, the application of multivariate pattern-recognition methods to metabolite profiles derived from the different strains using 1H nuclear magnetic resonance spectroscopy (metabolomics) was able to classify the different profiles. The two different ecotypes were clearly separated on the basis of their metabolite profiles, showing that it is possible to use metabolomic methods to classify pathogens on the basis of their expressed physiology, even when it is not possible to infer a direct mechanistic link to specific virulence factors. This metabolomic approach could also have a wide range of possible applications in both general microbiology and microbial ecology for distinguishing and identifying different functional/physiological ecotypes of bacterial strains or species.     

Supercritical fluid CO2 extraction accelerates isolation of humic acid from livePilayella littoralis (Phaeophyta)

Supercritical fluid CO₂ extraction of the live, dried algaPilayella littoralis efficiently removes non-humic substances in hours instead of the days required for sequential extraction with ether, acetone, ethanol and dioxane. Completion of extraction (including aqueous removal of alginic acids) with either preliminary in a standard procedure gives humic acid samples with closely comparable properties.Authors for correspondence     

Barley aleurone cells contain two types of vacuoles. Characterization Of lytic organelles by use of fluorescent probes

Light microscopy was used to study the structure and function of vacuoles in living protoplasts of barley (Hordeum vulgare cv Himalaya) aleurone. Light microscopy showed that aleurone protoplasts contain two distinct types of vacuole: the protein storage vacuole and a lysosome-like organelle, which we have called the secondary vacuole. Fluorescence microscopy using pH-sensitive fluorescent probes and a fluorogenic substrate for cysteine proteases showed that both protein storage vacuoles and secondary vacuoles are acidic, lytic organelles. Ratio imaging showed that the pH of secondary vacuoles was lower in aleurone protoplasts incubated in gibberellic acid than in those incubated in abscisic acid. Uptake of fluorescent probes into intact, isolated protein storage vacuoles and secondary vacuoles required ATP and occurred via at least two types of vanadate-sensitive, ATP-dependent tonoplast transporters. One transporter catalyzed the accumulation of glutathione-conjugated probes, and another transported probes not conjugated to glutathione.     

Morphogenetic surfactants and their role in the formation of aerial hyphae in Streptomyces coelicolor

Withstanding environmental adversity and seeking optimal conditions for reproduction are basic requirements for the survival of all organisms. Filamentous bacteria of the genus Streptomyces produce a remarkable cell type called the aerial hyphae that is central to its ability to meet both of these challenges. Recent advances have brought about a major shift in our understanding of the cell surface proteins that play important roles in the generation of these cells. Here we review our current understanding of one of these groups of proteins, the morphogenetic surfactants, with emphasis on the SapB protein of Streptomyces coelicolor.     

Distributions of five common point mutants in the human tracheal-bronchial epithelium

The mutations C742T, G746T, G747T in the TP53 gene and G35T in the KRAS gene have been repeatedly found in sectors of human tumors by direct DNA sequencing. The mutation G508A in the HPRT1 gene has been repeatedly found among peripheral T lymphocytes by clonal expansion under selective conditions. To discover if these mutations also occur frequently in normal tissues from which tumors arise, we have developed and validated allele-specific mismatch amplification mutation assays (MAMA) for each mutation. Reconstruction experiments demonstrated linearity in the range of 9-3000 mutant alleles among 3 x 10(6) wild-type alleles. The cumulative distributions of all negative controls established robust detection limits (P<0.05) of 34-125 mutants per 10(6) copies assayed depending on the mutation. One hundred and seventy-seven micro-anatomical samples of approximately (0.5-6)x10(6) tracheal-bronchial epithelial cells from nine non-smokers were assayed representing en toto the equivalent of approximately 1.6 human bronchial trees to the fifth bifurcation. Statistically significant mutant copy numbers were found in 257 of 463 assays. Clusters of mutant copies ranged from 10 to 1000 in 239/257 positive samples. As all five point mutations were detected at mutant fractions of >10(-5) in two or more lungs, we infer that they are mutational hotspots generated in lung epithelial stem cells. As the cancer-associated mutations did not differ in cluster size distribution from the HPRT1 mutation, we infer that none of the mutations conferred a growth advantage to somatic heterozygous clusters or maintenance turnover units. Specific mutants appeared in very large copy numbers, 1000-35,000, in 18/257 positive assays. Various hypotheses to account for the observed cluster size distributions are offered.