Selection of methods of detecting lactose-fermenting Salmonella strains and evaluating their usefulness for diagnostic studies

Salmonella rods of subspecies I, lactose-fermenting were first isolated in Poland in 1980. They were isolated from a plus sample taken from a brain abscess of a child. Next strains were isolated from faeces of newborn and hospitalized children. Growth characteristic of colonies of lactose-fermenting Salmonella strains on selective-differentiating media (Mac Conkey's Levine, SS, So?tys) recommended for inoculation of clinical material resembled Escherichia coli. So far these type of colonies were omitted in diagnostic examinations. Lactose-fermenting variants showed on Bismuth sulfate agar "Difco" (WB) typical for Salmonella growth pattern. They grew on this medium after 48 hr of incubation in a form of black, medium sized colonies, with some metallic brilliance and characteristic blackening of the medium undercolonies. Precise knowledge of biochemical properties of lactose-fermenting Salmonella allows to supplement so far used diagnostic scheme with additional tests permitting differentiation of lactose-fermenting variants of Salmonella from the other members of Enterobacteriaceae family. Taking into consideration biochemical variants in diagnostic procedure i.e. lactose-fermenting Salmonella, allowedns to isolate in the years 1983-1985 lactose-positive strains in 1305 out of 2773 (47%) individuals positive for S. agona. In 1987, 246 persons (28.3%) out of 869 with lactose-fermenting Salmonella of various serotypes were simultaneously infected with lactose-negative variant. Lactose-fermenting strains of Salmonella belonged most frequently to the following genera: S. agona, S. enteritidis, S. oranienburg, S. typhimurium, and S. goldcoast. It was found that the modified diagnostic procedure makes possible the isolation and the identification of lactose-positive varians of Salmonella.     

Distribution and frequency of neuro-epithelial bodies in post-natal rabbit lung: Quantitative study with monoclonal antibody against serotonin

Summary The distribution, frequency and size of neuroepithelial bodies (NEB) were studied in lungs of rabbits during different stages of development (27-day fetus, newborn, 6, 11, 21, 28 and 56 days postnatally). NEB were visualized by immunostaining with monoclonal antibody against serotonin. Detailed quantitiation of NEB was performed by use of camera lucida drawings of immunostained serial sections from the same anatomical region, i.e. the lower lobe of the left lung. The total number of NEB was counted and expressed per epithelial length of airway, surface area and volume. The size of NEB defined as surface area as well as the position of NEB in relation to the airway bifurcations was assessed in airways of different sizes. The overall number and size of NEB were found to increase during the immediate perinatal period followed by a sharp decline at 56 days of age. The number of NEB peaked at 6 days postnatally (mean 175.5 NEB/mm³ of airway epithelium) and declined significantly (3.0 NEB/mm³) at 56 days of postnatal age. The size of NEB reached its maximum at 11 days (mean surface area 659.54 m², with the largest NEB measuring 1839.98 m²). By 56 days of age, NEB became significantly smaller (mean surface area 177.29 m²) consisting of small clusters of cells situated deep within the airway epithelium. At all ages, about half of all NEB (mean 47.6%) were localized within the small peripheral airways with up to 63.9% located at airway bifurcations. These findings indicate that the functional activity of NEB may be confined predominantly to the perinatal period. The postulated functions of NEB include those of intrapulmonary hypoxia-sensitive chemoreceptors and/or endocrine-paracrine activity in the lung. Such function(s) may be important during adaptation to extrauterine life as well as for growth and development of the lung.     

Metabolism of d-xylose in Schizosaccharomyces pombe cloned with a xylose isomerase gene

Summary The Escherichia coli xylose isomerase gene was transformed into Schizosaccharomyces pombe for direct d-xylose utilization. In order to understand d-xylose metabolism and determine the limiting factors on d-xylose utilization by the transformed yeast, d-xylose transport, xylose isomerization, and xylulose phosphorylation were investigated. The results indicated that low activity of xylose isomerization in the cloned yeast was the limiting step for d-xylose fermentation. An in vitro study showed that yeast proteases decreased xylose isomerase activity. Xylitol, a by-product of d-xylose fermentation, had no effect on the activity of xylose isomerase.     

The primary structure of rat ribosomal protein L18a

The amino acid sequence of rat ribosomal protein L18a was deduced from the sequence of nucleotides in a recombinant cDNA. Ribosomal protein L18a contains 175 amino acids and has a molecular mass of 20,047 Da. Hybridization of the cDNA to digests of rat nuclear DNA and to a preparation of poly(A)+ mRNA suggests that there are 8-11 copies of the L18a gene and that the mRNA for the protein is about 700 nucleotides in length. Rat L18a is related to Schizosaccharomyces pombe L17 and perhaps to Halobacterium marismortui L19.     

Soluble derivatives of the beta amyloid protein precursor of Alzheimer's disease are labeled by antisera to the beta amyloid protein

The amyloid deposited in Alzheimer's disease (AD) is composed primarily of a 39-42 residue polypeptide (beta AP) that is derived from a larger beta amyloid protein precursor (beta APP). In previous studies, we and others identified full-length, membrane-associated forms of the beta APP and showed that these forms are processed into soluble derivatives that lack the carboxyl-terminus of the full-length forms. In this report, we demonstrate that the soluble approximately 125 and approximately 105 kDa forms of the beta APP found in human cerebrospinal fluid are specifically labeled by several different antisera to the beta AP. This finding indicates that both soluble derivatives contain all or part of the beta AP sequence, and it suggests that one or both of these forms may be the immediate precursor of the amyloid deposited in AD.     

Actin assembly in electropermeabilized neutrophils: role of G-proteins

Polymerization of microfilaments, one of the responses triggered in neutrophils by stimuli such as the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP), involves the conversion of actin from the monomeric to the filamentous form. The exact sequence of events responsible for this conversion remains to be defined, but its susceptibility to inhibition by pertussis toxin provides indirect evidence that GTP-binding proteins (G-proteins) are involved. In this report, electropermeabilized cells were used to obtain more direct evidence of a role for G-proteins in actin assembly. Staining with 7-nitrobenz-2-oxa-1,3-diazole (NBD)-phallacidin and flow cytometry were used to monitor the formation of filamentous actin. GTP-gamma-S, a nonhydrolyzable analogue of GTP and aluminum fluoride, which in combination with GDP can activate G-proteins, stimulated actin assembly in electropermeabilized cells but had only marginal effects on intact cells. fMLP-induced actin polymerization in permeabilized cells was inhibited by pretreatment with GDP-beta-S, an analogue of GDP that stabilizes the inactive form of G-proteins. In contrast, stimulation by phorbol 12-myristate 13-acetate (PMA) was largely unaffected by GDP-3-S. These observations indicate that activation of G-proteins is essential for actin assembly induced by receptor-dependent stimuli such as fMLP. Moreover, GTP-binding proteins do not seem to be required in the late stages of the signalling cascade, i.e. after stimulation of protein kinase C.     

Cloning, analysis, and bacterial expression of human farnesyl pyrophosphate synthetase and its regulation in Hep G2 cells

A partial length cDNA encoding farnesyl pyrophosphate synthetase (hpt807) has been isolated from a human fetal liver cDNA library in lambda gt11. DNA sequence analysis reveals hpt807 is 1115 bp in length and contains an open reading frame coding for 346 amino acids before reaching a stop codon, a polyadenylation addition sequence, and the first 14 residues of a poly(A+) tail. Considerable nucleotide and deduced amino acid sequence homology is observed between hpt807 and previously isolated rat liver cDNAs for farnesyl pyrophosphate synthetase. Comparison with rat cDNAs suggests that hpt807 is about 20 bp short of encoding the initiator methionine of farnesyl pyrophosphate synthetase. The human cDNA was cloned into a prokaryotic expression vector and Escherichia coli strain DH5 alpha F'IQ was transformed. Clones were isolated that express an active fusion protein which can be readily observed on protein gels and specifically stained on immunoblots with an antibody raised against purified chicken farnesyl pyrophosphate phosphate synthetase. These data confirm the identity of hpt807 as encoding farnesyl pyrophosphate synthetase. Slot blot analyses of RNA isolated from Hep G2 cells show that the expression of farnesyl pyrophosphate synthetase mRNA is regulated. Lovastatin increases mRNA levels for farnesyl pyrophosphate synthetase 2.5-fold while mevalonic acid, low-density lipoprotein, and 25-hydroxycholesterol decrease mRNA levels to 40-50% of control values.     

The primary structure of human apolipoprotein A-IV

Human apolipoprotein (apo) A-IV was purified from chylous ascites fluid. Proteolytic peptides produced by trypsin and Staphylococcus aureus V8 proteinase digestions were purified by high-performance liquid chromatography and sequenced. Human apoA-IV contains 376 amino acid residues. The peptide-derived sequence generally matches two previously reported DNA-derived amino acid sequences except for discrepancies in five positions. In order to examine these discrepancies further, one complete apoA-IV cDNA clone and another partial clone were sequenced. Comparison of all the available information indicates that the peptide-derived sequence reported here is accurate. Sequencing errors probably account for some of the discrepancies between the two primary sequences predicted by earlier nucleotide analyses. In certain positions, however, bona fide sequence heterogeneity or cloning artifact cannot be excluded.