Differential effects of (S)- and (R)-enantiomers of albuterol in a mouse asthma model

BACKGROUND: (R)- and (S)-Enantiomers of albuterol likely exert differential effects in patients with asthma. The (R)-enantiomer binds to the beta2-adrenergic receptor with greater affinity than the (S)-enantiomer and is responsible for albuterol's bronchodilating activity. (S)-Albuterol augments bronchospasm and has proinflammatory actions. OBJECTIVE: The study aim was to determine whether the (S)-enantiomer, in contrast to the (R)-enantiomer, has adverse effects on allergic airway inflammation and hyperresponsiveness in a mouse asthma model. METHODS: Mice sensitized to ovalbumin (OVA) intraperitoneally on days 0 and 14 were challenged with OVA intranasally on days 14, 25, and 35. On day 36, 24 hours after the final allergen challenge, the effect of the (R)- and (S)-enantiomers of albuterol (1 mg x kg(-1) x d(-1) administered by means of a miniosmotic pump from days 13-36) on airway inflammation and hyperreactivity was determined. RESULTS: In OVA-sensitized/OVA-challenged mice, (R)-albuterol significantly reduced the influx of eosinophils into the bronchoalveolar lavage fluid and airway tissue. (R)-Albuterol also significantly decreased airway goblet cell hyperplasia and mucus occlusion and levels of IL-4 in bronchoalveolar lavage fluid and OVA-specific IgE in plasma. Although (S)-albuterol significantly reduced airway eosinophil infiltration, goblet cell hyperplasia, and mucus occlusion, it increased airway edema and responsiveness to methacholine in OVA-sensitized/OVA-challenged mice. Allergen-induced airway edema and pulmonary mechanics were unaffected by (R)-albuterol. CONCLUSION: Both (R)- and (S)-enantiomers of albuterol reduce airway eosinophil trafficking and mucus hypersecretion in a mouse model of asthma. However, (S)-albuterol increases allergen-induced airway edema and hyperresponsiveness. These adverse effects of the (S)-enantiomer on lung function might limit the clinical efficacy of racemic albuterol.     

Actions of phencyclidine on rat locus coeruleus neurones in vitro

Intracellular recordings were made from neurones in the rat locus coeruleus in a brain slice maintained in vitro. Phencyclidine and related psychotomimetic drugs, applied in known concentrations in the fluid bathing the slice, depressed responses to N-methyl-D-aspartic acid noradrenaline (in the presence of the uptake inhibitor desmethylimipramine) and [D-Ala2,MePhe4,Gly-ol5]enkephalin and also prolonged the action potential. The sensitivities of these responses to depression by phencyclidine was N-methyl-D-aspartic acid (IC50 0.4 microM) greater than noradrenaline (IC50 3.9 microM) greater than [D-Ala2,MePhe4,Gly-ol5]enkephalin (IC50 8.5 microM) greater than prolongation of the action potential (41% increase by 30 microM). Stereoselectivity was observed only in the depression of responses to N-methyl-D-aspartic acid where (+)-1-(1-phenylcyclohexyl)-3-methyl piperidine was 3.3-fold more potent in suppressing N-methyl-D-aspartic acid depolarizations than its (-) isomer. The responses to N-methyl-D-aspartic acid were also depressed by the structurally unrelated psychotomimetic (+/-)-N-allyl-N-normetazocine (IC50 0.9 microM). All of the effects of the psychotomimetic drugs examined were slow in onset and difficult to reverse following washout. No effect of phencyclidine (0.03-100 microM) or related drugs was observed on membrane potential, input resistance or spontaneous action potential firing rate of locus coeruleus neurones. The depression of responses to N-methyl-D-aspartic acid by phencyclidine was the most potent and the only stereoselective effect of those studied. The importance of this effect and of those not showing stereoselectivity in relation to the phencyclidine behavioural syndrome is discussed.     

Characterization of an inversion duplication of the short arm of chromosome 8 by fluorescent in situ hybridization

A de novo chromosome aberration in a woman with severe mental retardation and minor anomalies has been characterized cytogenetically. The patient's karyotype was described as 46, XX, inv dup (8)(p12 → p23.1). Previous Southern blot dosage studies with the marker locus D8S7 demonstrated that the patient was monosomic for this locus, suggesting that the rearrangement generated a duplication-deficiency chromosome. We have reinvestigated this patient using fluorescent in situ hybridization with chromosome 8 cosmids and an Alu-PCR product specific for 8p. These studies have confirmed directly that the duplicated chromosome also has undergone deletion. © 1992 Wiley-Liss, Inc.     

In vitro genotoxicity of dyes present in colored smoke munitions

Genetic toxicology studies were conducted on organic dyes and mixtures used in colored smoke munitions. The dyes studied included Solvent Red 1; two different batches (Lot 1 and Lot 2) of Disperse Red 11; terephthalic acid; and a mixture of 25 parts Solvent Red 1, 5 parts Disperse Red 11, and 16 parts terephthalic acid. The dyes were evaluated for their ability to produce mutations in Salmonella bacterial strains and in Chinese hamster ovary (CHO) cells. The dyes were also tested in CHO cells to determine cytotoxicity and the induction of sister chromatid exchanges and chromosome aberration. None of the dyes were genotoxic in the standard Ames assay using bacterial strain TA1535 or TA100 with or without the addition of S-9 or in TA98 and TA1538 without S-9. With S-9, Disperse Red 11 (Lot 2) showed significant mutagenic activity in TA98 and TA1538 which increased as a function of S-9 concentration. However, the maximum level of mutagenic activity detected was low (3.8 revertants/micrograms). The azo dye Solvent Red 1 was also negative in a pre-incubation assay designed to reduce azo compounds to free amines. Solvent Red 1 was cytotoxic to mammalian cells, caused a significant increase in SCE, but was not mutagenic or clastogenic. Disperse Red 11 (Lot 1 and Lot 2) were not cytotoxic or clastogenic but produced an increase in cell cycle time and SCE frequency. Only Disperse Red 11 (Lot 2) increased mutations in the CHO/hypoxanthine-guanine phosphoribosyltransferase (HGPRT) assay. The mutagenic activity of the dye mixture was not significant, suggesting no synergistic interaction between the dyes. These studies demonstrated that none of the dyes was clastogenic and that a contaminant in Disperse Red 11 (Lot 2) may be responsible for the weak mutagenic activity in both mammalian and bacterial cell systems.     

DNA Sequence analysis of the PorB protein of nonserotypeable serogroup C ET-15 meningococci suggests a potential mutational hot spot on their serotype antigens

The nucleotide sequences of the PorB proteins from 28 nonserotypeable serogroup C ET-15 meningococci recovered from invasive meningococcal disease cases were determined. PCR amplification of the porB genes responsible for encoding the serotype antigen was used for DNA sequence determination and identification of the nature of the serotype antigen. DNA sequencing revealed that three strains were of serotype 2a, and of the remaining 25 strains, 20 were found to have an identical single point mutation in the region of the VR3 gene, which encodes surface-exposed loop VI, where the serotype 2a epitope resides. This nonsynonymous mutation was confirmed by synthetic peptide immunochemical analysis to confer new serospecificity to these serotype 2a mutants. This finding of a potential novel mutational hot spot on the PorB proteins of meningococci may have implications for pathogenesis and vaccine development.     

Electrophysiological characteristics of non-bursting, glutamate decarboxylase messenger RNA-positive neurons of the medial septum/diagonal band nuclei of guinea-pig and rat

Nuclei of the medial septum/diagonal band region of the mammalian forebrain contain neurons that give rise to the septohippocampal pathway, which has separate cholinergic and GABAergic components. This pathway is known to influence hippocampal-dependent memory and learning processes, but the precise role of each component is unclear. In this study, we tested the hypothesis that fast-firing, non-bursting medial septum/diagonal band neurons are GABAergic. We used brain slice preparations from young adult guinea-pigs and rats, or from weanling rats, to perform current-clamp recordings from medial septum/diagonal band neurons. Recorded neurons were injected with biocytin for subsequent visualization with fluorescent avidin, and then hybridized with a 35S-labeled riboprobe for glutamate decarboxylase-67 messenger RNA. As a positive control, guinea-pig cerebellar Purkinje cells were labeled and hybridized with the riboprobe. As expected, labeled Purkinje cells were glutamate decarboxylase-67 messenger RNA positive. Slow-firing, cholinergic (choline acetyltransferase-positive) guinea-pig medial septum/diagonal band neurons were glutamate decarboxylase-67 messenger RNA negative. Contrary to our hypothesis, of the guinea-pig neurons, only three of 11 fast-firing neurons were glutamate decarboxylase-67 positive. Of the rat medial septum/diagonal band neurons, three of four were positive for glutamate decarboxylase-67 messenger RNA.These data suggest that fast-firing, non-bursting neurons of the medial septum/diagonal band, as sampled by sharp-electrode intracellular recordings in brain slices, may be a heterogeneous group of neurons, some of which are GABAergic. Together with recent data demonstrating the presence of another GABAergic marker, parvalbumin, in fast-firing septal neurons, we conclude that GABAergic septohippocampal neurons include a population of fast-firing, non-bursting neurons. The influence of these neurons on the hippocampus is likely to occur on a shorter time-scale and over a wider range of firing frequencies as compared to slowly firing cholinergic septohippocampal neurons.     

Immunological recovery after measles

Twenty-two children with measles were studied at the stage of the rash and 6 weeks later, and results compared with matched controls. The total lymphocyte count and lymphocyte subpopulations with T- and B-cell markers and those with absence of both markers (null cells) were significantly below control levels in the acute phase. At 6 weeks the B-cell and null-cell counts were still significantly diminished. The function of T cells assessed by 14C uptake of phytohaemagglutinin-stimulated lymphocytes and the delayed skin hypersensitivity reaction to dinitrochlorobenzene was impaired during the acute stage, and this persisted for 6 weeks. Over the 6 weeks of study there was a small but significant rise in serum IgG, IgM and complement factors.     

A clinical evaluation of the Cobas Fara clinical chemistry analyzer for some routine serum enzymes and glucose

The authors evaluated the Cobas FARA centrifugal analyzer with respect to pipetting precision and accuracy, instrument temperature, spectrophotometric response, and analytic performance for the assay of five serum enzymes and glucose. Spectrophotometric response, temperature response, pipetting precision, and accuracy were satisfactory. However, sufficient time must be allowed for cuvet contents to reach a stable temperature before measurements are made. Total day-to-day imprecision (within plus between run) was less than 5% (coefficient of variation) for aspartate and alanine aminotransferases (AST; Enzyme Commission classification number [EC] EC 2.6.1.1; and ALT; EC 2.6.1.2); alkaline phosphatase (AP; EC 3.1.3.1); gamma-glutamyltransferase (GGT; EC 2.3.1.2); lactate dehydrogenase (LD; EC 1.1.1.17); creatine kinase (CK; EC 2.7.3.1); and glucose assays. Results compare well with those obtained with other current clinical chemistry analyzers; correlation coefficients were greater than 0.993. Sample-to-sample carryover was negligible, and method linearity was satisfactory for all tests.