Characteristics of Helicobacter pylori attachment to human primary antral epithelial cells.

Conventional cell lines are commonly used to study infection characteristics of the human gastric pathogen Helicobacter pylori. We sought to investigate bacterial attachment to human antral primary epithelial cells, a cell model that more closely resembles the human stomach than transformed cell lines. Primary cells were infected for 24 and 48 h with H.

Structure of the bovine antimicrobial peptide indolicidin bound to dodecylphosphocholine and sodium dodecyl sulfate micelles.

Indolicidin is a cationic, 13-residue antimicrobial peptide (ILPWKWPWWPWRR-NH(2)) which is unusually rich in tryptophan and proline. Its antimicrobial action involves the bacterial cytoplasmic membrane. Fluorescence and circular dichroism spectra demonstrated the structural similarity of indolicidin in complexes with large unilamellar phospolipid vesicles and with detergent micelles.

Signalling molecules involved in cellular differentiation during Dictyostelium morphogenesis.

GSK-3, Dd-STATa, PKA, rZIP and Ras all play important roles in cell type determination of Dictyostelium discoideum. The fact that homologs of these proteins also function in metazoan development emphasizes the importance of Dictyostelium as a model microbial organism for studying the molecular mechanisms that regulate development. The recent elaboration of the central role for GSK-3 in cell type determination has been of particular importance.

Interaction of polyphemusin I and structural analogs with bacterial membranes, lipopolysaccharide, and lipid monolayers.

Three structural variants (PV5, PV7, and PV8) of the horseshoe crab cationic antimicrobial peptide polyphemusin I were designed with improved amphipathic profiles. Circular dichroism spectroscopy analysis indicated that in phosphate buffer polyphemusin I, PV7, and PV8 displayed the spectrum of a type II beta-turn-rich structure, but, like polyphemusin I, all three variants adopted a typical beta-sheet structure in an anionic lipid environment. Both polyphemusin I and variants were potent broad spectrum antimicrobials that were clearly bactericidal at their minimal inhibitory concentrations.

Cationic antimicrobial peptides: towards clinical applications.

Cationic antimicrobial peptides are important components of the innate immune defences of all species of life. Variants of these natural molecules have a broad range of antibiotic, antifungal, antiviral and anti-endotoxic activity. Two of these cationic peptides have shown signs of efficacy in early clinical trials of oral mucositis and the sterilisation of central venous catheters, respectively and are currently proceeding through Phase III clinical trials.

Identification of Glu-519 as the catalytic nucleophile in beta-mannosidase 2A from Cellulomonas fimi.

Incubation of the beta-mannosidase Man2A from Cellulomonas fimi with 2-deoxy-2-fluoro-beta-D-mannosyl fluoride (2FMan beta F) resulted in time-dependent inactivation of the enzyme (inactivation rate constant k(i)=0.57 min(-1), dissociation constant for the inactivator K(i)=0.41 mM) through the accumulation of a covalent 2-deoxy-2-fluoro-alpha-D-mannosyl-beta-mannosidase 2A (2FMan-Man2A) enzyme intermediate, as observed by electrospray ionization mass spectrometry.

Increased t-PA yields using ultrafiltration of an inhibitory product from CHO fed-batch culture.

Fed-batch operation for the production of t-PA using Chinese Hamster Ovary (CHO) cells was optimized using serial and parallel experimentation. The feed, an isotonic concentrate, was improved to obtain 2- to 2.5-fold increases in integrated viable cell days versus batch.

Role of Pseudomonas aeruginosa PhoP-phoQ in resistance to antimicrobial cationic peptides and aminoglycosides.

Resistance to the polycationic antibiotic polymyxin B and expression of the outer-membrane protein OprH in the opportunistic pathogen Pseudomonas aeruginosa both involve the PhoP-PhoQ two-component regulatory system. The genes for this system form an operon with oprH, oprH-phoP-phoQ, that responds to Mg(2+) starvation and PhoP levels. In this study, the Mg(2+)-regulated promoter for this operon was mapped upstream of oprH by primer-extension experiments.

Limitations to the amplification and stability of human tissue-type plasminogen activator expression by Chinese hamster ovary cells.

Chinese hamster ovary cell production of recombinant tissue-type plasminogen activator (t-PA) was increased by amplification of cotransfected dihydrofolate reductase cDNA using stepwise adaptation to increasing methotrexate (MTX) concentrations. The highest producing clones were isolated at 5 microM MTX and yielded 26,000 U/10(6) cells/day t-PA (43 microgram/10(6) cells/day). Above 25 microM MTX, cell specific t-PA production rates became increasingly variable and the cDNA copynumbers decreased.

Gaping lids, gp, a mutation on centromeric chromosome 11 that causes defective eyelid development in mice.

In mammals, during fetal development, the eyelids grow and flatten over the eyes and temporarily fuse closed. Failure of this normal developmental process in mice leads to the defect, open-eyelids-at-birth. Nearly all newborns of the GP/Bc strain, homozygous for the spontaneous recessive mutation, gaping lids (gp), have bilateral open eyelids at birth, with essentially no fusion between the upper and lower eyelids.

Mouse models for neural tube closure defects.

Neural tube closure defects (NTDs), in particular anencephaly and spina bifida, are common human birth defects (1 in 1000), their genetics is complex and their risk is reduced by periconceptional maternal folic acid supplementation. There are > 60 mouse mutants and strains with NTDs, many reported within the past 2 years. Not only are NTD mutations at loci widely heterogeneous in function, but also most of the mutants demonstrate variable low penetrance and some show complex inheritance patterns (e.

Quantitation of the Population Size and Metabolic Activity of a Resin Acid Degrading Bacterium in Activated Sludge Using Slot-Blot Hybridization to Measure the rRNA:rDNA Ratio.

The 16S rRNA:rDNA ratio is a useful parameter for measuring metabolic activity of a selected member of a complex microbial community, as in pulp effluent activated sludge systems. The RNA:DNA ratio of Sphingomonas sp. DhA-33, previously isolated from a sequencing batch reactor treating pulp mill effluent, is positively correlated with its growth rate (µ) under steady-state conditions.

Salmonella pathogenicity islands: big virulence in small packages.

Reflecting a complex set of interactions with its host, Salmonella spp. require multiple genes for full virulence. Many of these genes are found in 'pathogenicity islands' in the chromosome.

Genetic analysis of a bacterial genetic exchange element: the gene transfer agent of Rhodobacter capsulatus.

An unusual system of genetic exchange exists in the purple nonsulfur bacterium Rhodobacter capsulatus. DNA transmission is mediated by a small bacteriophage-like particle called the gene transfer agent (GTA) that transfers random 4.5-kb segments of the producing cell's genome to recipient cells, where allelic replacement occurs.

Growth in North American white children with neurofibromatosis 1 (NF1).

Objective: To analyse the distributions of and generate growth charts for stature and occipitofrontal circumference (OFC) in neurofibromatosis 1 (NF1) patients.

Design: Cross sectional database survey.

Setting: The National Neurofibromatosis Foundation International Database (NFDB) includes clinical information on NF1 patients from 14 participating centres in North America.

Components of the spindle-assembly checkpoint are essential in Caenorhabditis elegans.

The spindle-assembly checkpoint ensures that, during mitosis and meiosis, chromosomes do not segregate until they are properly attached to the microtubules of the spindle. Here we show that mdf-1 and mdf-2 are components of the spindle-assembly checkpoint in Caenorhabditis elegans, and are essential for the long-term survival and fertility of this organism. Loss of function of either of these genes leads to the accumulation of a variety of defects, including chromosome abnormalities, X-chromosome non-disjunction or loss, problems in gonad development, and embryonic lethality.

PhoP-PhoQ homologues in Pseudomonas aeruginosa regulate expression of the outer-membrane protein OprH and polymyxin B resistance.

Rapid adaptation to environmental challenge is essential for the survival of many bacterial species, and is often effectively mediated by two-component regulatory systems. Part of the adaptive response of Pseudomonas aeruginosa to Mg2+ starvation is overexpression of the outer-membrane protein OprH and increased resistance to the polycationic antibiotic polymyxin B. Two overlapping open reading frames that encoded proteins with high similarities to the PhoP-PhoQ two-component regulatory system of Salmonella typhimurium were identified downstream of the oprH gene.

Characterization of a vanillic acid non-oxidative decarboxylation gene cluster from Streptomyces sp. D7.

The genetics of non-oxidative decarboxylation of aromatic acids are poorly understood in both prokaryotes and eukaryotes. Although such reactions have been observed in numerous micro-organisms acting on a variety of substrates, the genes encoding enzymes responsible for these processes have not, to our knowledge, been reported in the literature. Here, the isolation of a streptomycete from soil (Streptomyces sp.

Efficient infection of mature skeletal muscle with herpes simplex virus vectors by using dextran sulfate as a co-receptor.

The use of herpes simplex virus (HSV) vectors for gene delivery to skeletal muscle is hampered by a maturation-dependent loss of muscle fiber infectivity. Previous studies of HSV type 1 (HSV-1) infection in the rodent show that the loss of infectivity may be due, at least in part, to the development of the basal lamina throughout the course of maturation, which may block the initial events in HSV infection. To initiate infection, HSV normally attaches to cell surface heparan sulfate, which stabilizes the virus such that it can interact with secondary protein receptors required for entry into host cells.

Recent advances in understanding resin acid biodegradation: microbial diversity and metabolism.

Resin acids are tricyclic diterpenoids that are found in the oleoresin of coniferous trees. Resin-acid-degrading microorganisms are ubiquitous in the environment. The bacterial isolates that grow on resin acids as sole organic substrates are physiologically and phylogenetically diverse, and include psychrotolerant, mesophilic, and thermophilic bacteria.

Cellulose as an inert matrix for presenting cytokines to target cells: production and properties of a stem cell factor-cellulose-binding domain fusion protein.

A chimaera of stem cell factor (SCF) and a cellulose-binding domain from the xylanase Cex (CBDCex) effectively immobilizes SCF on a cellulose surface. The fusion protein retains both the cytokine properties of SCF and the cellulose-binding characteristics of CBDCex. When adsorbed on cellulose, SCF-CBDCex is up to 7-fold more potent than soluble SCF-CBDCex and than native SCF at stimulating the proliferation of factor-dependent cell lines.

Concentration-dependent internalization of a cytokine/cytokine receptor complex in human hematopoietic cells.

Soluble steel factor (SF) is a potent stimulator of hematopoietic progenitor cell proliferation in vitro, and cytokine combinations that include SF can support extensive expansions of hematopoietic cells. Recently, we showed that very primitive progenitor cells from normal human bone marrow require exposure to very high concentrations of cytokines to maintain their primitive status while proliferating. These cells also display higher cell-specific cytokine uptake rates than more differentiated types of hematopoietic cells.

Predictive control of hollow-fiber bioreactors for the production of monoclonal antibodies.

The selection of medium feed rates for perfusion bioreactors represents a challenge for process optimization, particularly in bioreactors that are sampled infrequently. When the present and immediate future of a bioprocess can be adequately described, predictive control can minimize deviations from set points in a manner that can maximize process consistency. Predictive control of perfusion hollow-fiber bioreactors was investigated in a series of hybridoma cell cultures that compared operator control to computer estimation of feed rates.