Molecular genetics of met 17 and met 25 mutants of Saccharomyces cerevisiae: intragenic complementation between mutations of a single structural gene

Summary A method for transposon mutagenesis in Azospirillum lipoferum 29708 is reported with transposon Tn5. The suicide plasmid pSUP2021 was used to deliver Tn5 in A. lipoferum using Escherichia coli SM10 as the donor. Neomycin-resistant transconjugants were detected at a frequency of 6x10^-6 per recipient. Different types of mutants were isolated, e.g. auxotrophic, coloured, IAA-negative, and IAA-overproducers. Among the auxotrophic mutants, cysteine and methionine requirers prevailed. Random Tn5-insertion with only one copy per mutant was demonstrated by Southern blotting and hybridization. Tn5-induced mutants are relatively stable, with reversion rates of 2–20×10^-8. A gene which is a part of the carotenoid pathway is closely linked to the histidine genes. The existence of two pathways for IAA production in A. lipoferum is discussed.     

A new case of neonatal progeroid syndrome with agenesis of corpus callosum

We report on a female infant with a history of severe intrauterine and postnatal growth retardation, pseudohydrocephaloid cranium, frontal bossing, widened fontanelles, prominent scalp veins, progeroid face, entropion, beaked nose, small mouth, generalized lipodystrophy, camptodactyly and hypoplasia of lower limb muscles, suggesting the diagnosis of neonatal progeroid syndrome (NPS). In addition, she had congenital hip dysplasia and agenesis of corpus callosum. It is the first Hungarian case with neonatal progeroid syndrome.     

Tablet formulation containing meloxicam and β-cyclodextrin: Mechanical characterization and bioavailability evaluation

The purpose of this research was to evaluate β-cyclodextrin (β-CD) as a vehicle, either singly or in blends with lactose (spray-dried or monohydrate), for preparing a meloxicam tablet. Aqueous solubility of meloxicam in presence of β-CD was investigated. The tablets were prepared by direct compression and wet granulation techniques. The powder blends and the granules were evaluated for angle of repose, bulk density, compressibility index, total porosity, and drug content. The tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, disintegration time, and in vitro dissolution studies. The effect of β-CD on the bioavailability of meloxicam was also investigated in human volunteers using a balanced 2-way crossover study. Phase-solubility studies indicated an A_L-type diagram with inclusion complex of 1∶1 molar ratio. The powder blends and granules of all formulations showed satisfactory flow properties, compressibility, and drug content. All tablet formations prepared by direct compression or wet granulation showed acceptable mechanical properties. The dissolution rate of meloxicam was significantly enhanced by inclusion of β-CD in the formulations up to 30%. The mean pharmacokinetic parameters (C_max, K_e, and area under the curve [AUC]_0−∞) were significantly increased in presence of β-CD. These results suggest that β-CD would facilitate the preparation of meloxicam tablets with acceptable mechanical properties using the direct compression technique as there is no important difference between tablets prepared by direct compression and those prepared by wet granulation. Also, β-CD is particularly useful for improving the oral bioavailablity of meloxicam.     

Tablet formulation containing meloxicam and beta-cyclodextrin: mechanical characterization and bioavailability evaluation

The purpose of this research was to evaluate beta-cyclodextrin (beta-CD) as a vehicle, either singly or in blends with lactose (spray-dried or monohydrate), for preparing a meloxicam tablet. Aqueous solubility of meloxicam in presence of beta-CD was investigated. The tablets were prepared by direct compression and wet granulation techniques. The powder blends and the granules were evaluated for angle of repose, bulk density, compressibility index, total porosity, and drug content. The tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, disintegration time, and in vitro dissolution studies. The effect of beta-CD on the bioavailability of meloxicam was also investigated in human volunteers using a balanced 2-way crossover study. Phase-solubility studies indicated an A(L)-type diagram with inclusion complex of 1:1 molar ratio. The powder blends and granules of all formulations showed satisfactory flow properties, compressibility, and drug content. All tablet formulations prepared by direct compression or wet granulation showed acceptable mechanical properties. The dissolution rate of meloxicam was significantly enhanced by inclusion of beta-CD in the formulations up to 30%. The mean pharmacokinetic parameters (C(max), K(e), and area under the curve [AUC](0-infinity)) were significantly increased in presence of beta-CD. These results suggest that beta-CD would facilitate the preparation of meloxicam tablets with acceptable mechanical properties using the direct compression technique as there is no important difference between tablets prepared by direct compression and those prepared by wet granulation. Also, beta-CD is particularly useful for improving the oral bioavailablity of meloxicam.     

Characterization of<Emphasis Type="Italic">Cryptococcus neoformans</Emphasis> var.<Emphasis Type="Italic">neoformans</Emphasis> serotype A and A/D in samples from Egypt

The cryptococcal polysaccharide antigen was detected in 10 cerebrospinal fluid (CSF) and 23 serum samples from cryptococcal meningitis and intestinal cryptococcosis by the cryptococcal antigen latex agglutination system (CALAS). CALAS titers in CSF and serum samples of cryptococcal meningitis ranged over 8-2048 and 32-2048, respectively, while in cases of intestinal cryptococcosis, serum titers ranged over 8-2048. The isolates of yeast Cryptococcus neoformans were determined to be of serotype A or of the A/D pair. The total leukocyte count and biochemical parameters in CSF were significantly increased as indicators of microbial infection. Furthermore, the in vitro change of the teleomorph (sexual state) to the anamorph (asexual state) was also detected and the teleomorph state changed in vivo to the encapsulated anamoph state which is more virulent during infection in vivo than the yeast-like noncapsulated form. Two primers for internal transcribed spacer (ITS) regions of ribosomal DNA were used for molecular detection of C. neoformans. After PCR amplification, a DNA band of 415 bp, visualized on agarose gel, indicated the presence of C. neoformans cells in the tested CSF and serum samples. The primer sensitivity was also characterized using purified yeast chromosomal DNA as template; it was about 20 pg or more chromosomal DNA which represents about 10 cells of C. neoformans. The primers were also specific for ITS regions of C. neoformans and gave negative results with Candida albicans and E. coli chromosomal DNA templates.     

Microcephaly, microphthalmia, congenital cataract, with calcification of the basal ganglia: MCA/MR syndrome

We present a Hungarian girl with microcephaly, microphthalmia, congenital cataract, prominent nasal root, peaked nose, micrognathia with high arched palate, mild mental retardation, calcification of the basal ganglia and serology for the connatal infections. We suggest that our proband may be an allelic variant of COFS syndrome.     

Gastric mucosal integrity: gastric mucosal blood flow and microcirculation. An overview

The stomach is in a state of continuous exposure to potentially hazardous agents. Hydrochloric acid together with pepsin constitutes a major and serious threat to the gastric mucosa. Reflux of alkaline duodenal contents containing bile and pancreatic enzymes are additional important injurious factors of endogenous origin. Alcohol, cigarette smoking, drugs and particularly aspirin and aspirin-like drugs, and steroids are among exogenous mucosal irritants that can inflict mucosal injury. The ability of the stomach to defend itself against these noxious agents has been ascribed to a number of factors constituting the gastric mucosal defense. These include mucus and bicarbonate secreted by surface epithelial cells, prostaglandins, sulfhydryl compounds and gastric mucosal blood flow. The latter is considered by several researchers to be of paramount importance in maintaining gastric mucosal integrity. The aim of this paper is to review the experimental and clinical data dealing with the role of mucosal blood flow and in particular the microcirculation in both damage and protection of the gastric mucosa.     

A mosquito predator survey in Townsville, Australia, and an assessment of Diplonychus sp. and Anisops sp. predatorial capacity against Culex annulirostris mosquito immatures.

A twelve-month survey for mosquito predators was conducted in Townsville, Queensland, Australia, which is located in the arid tropics. The survey revealed the presence of five predaceous insects but only Anisops sp. (backswimmers) and Diplonychus sp. were common. Predatorial capacity and factors influencing this capacity were then assessed for adult Anisops sp. and adult and nymph stages of Diplonychus sp. against Culex annulirostris mosquito immatures under laboratory conditions. Predatorial capacity bioassays showed that adult Diplonychus sp. preyed upon both larval and pupal stages of Cx. annulirostris quite successfully. Nymphs of Diplonychus sp. proved to be more successful with smaller prey immatures, and Anisops sp adults did not prey successfully on any prey pupae. Increasing the foraging area and introducing aquatic vegetation significantly reduced the predatorial capacity of Diplonychus sp. nymphs, while only vegetation and not foraging area had a significant effect on adult Diplonychus sp. predation capacity. Overall, adult Diplonychus sp. proved to be a more efficient predator than Anisops sp., and field trials are now recommended to further assess the potential of Diplonychus sp. as a biocontrol agent.     

Capsaicin-sensitive afferent sensory nerves in modulating gastric mucosal defense against noxious agents.

In the rat stomach, evidence has been provided that capsaicin-sensitive sensory nerves (CSSN) are involved in a local defense mechanism against gastric ulcer. In the present study capsaicin or resiniferatoxin (RTX), a more potent capsaicin analogue, was used to elucidate the role of these sensory nerves in gastric mucosal protection, mucosal permeability, gastric acid secretion and gastrointestinal blood flow in the rat. In the rat stomach and jejunum, intravenous RTX or topical capsaicin or RTX effected a pronounced and long-lasting enhancement of the microcirculation at these sites, measured by laser Doppler flowmetry technique. Introduction of capsaicin into the rat stomach in very low concentrations of ng-microg x mL(-1) range protected the gastric mucosa against damage produced by topical acidified aspirin, indomethacin, ethanol or 0.6 N HCl. Resiniferatoxin exhibited acute gastroprotective effect similar to that of capsaicin and exerted marked protective action on the exogenous HCl, or the secretagogue-induced enhancement of the indomethacin injury. The ulcer preventive effect of both agents was not prevented by atropine or cimetidine treatment. Capsaicin given into the stomach in higher desensitizing concentrations of 6.5 mM markedly enhanced the susceptibility of the gastric mucosa and invariably aggravated gastric mucosal damage evoked by later noxious challenge. Such high desensitizing concentrations of capsaicin, however, did not reduce the cytoprotective effect of prostacyclin (PGI2) or beta-carotene. Capsaicin or RTX had an additive protective effect to that of atropine or cimetidine. In rats pretreated with cysteamine to deplete tissue somatostatin, capsaicin protected against the indomethacin-induced mucosal injury. Gastric acid secretion of the pylorus-ligated rats was inhibited with capsaicin or RTX given in low non-desensitizing concentrations, with the inhibition being most marked in the first hour following pylorus-ligation. Low intragastric concentrations of RTX reduced gastric hydrogen ion back-diffusion evoked by topical acidified salicylates. It is concluded that the gastropotective effect of capsaicin-type agents involves primarily an enhancement of the microcirculation effected through local release of mediator peptides from the sensory nerve terminals. A reduction in gastric acidity may contribute to some degree in the gastric protective action of capsaicin-type agents. The vasodilator and gastroprotective effects of capsaicin-type agents do not depend on vagal efferents or sympathetic neurons, involve prostanoids, histaminergic or cholinergic pathways.