The Use of Carbon Substrate Utilization Patterns in Environmental and Ecological Microbiology
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Journal Article↗
Biomedical subjects
L Oliver
Publications and source records attributed to L Oliver.
Analysis of nuclear degradation during lens cell differentiation.
Lens cells demonstrate a terminal differentiation process with loss of their organelles including nuclei. Chromatin disappearance is characterised by the same changes as most apoptotic cells, i.e. condensation of chromatin and cleavage into high molecular weight fragments and oligonucleosomes. The endo-deoxyribonucleases (bicationic (Ca2+, Mg2+), mono-cationic (Ca2+ or Mg2+) and acidic non-cationic dependent nucleases) are present in lens fibre cells. Our results suggest that the acidic non-cationic nuclease (DNase II) plays a major role in chromatin cleavage. This nuclease, known to be lysosomal, is found in lens fibre nuclei and only an antibody directed against DNase II inhibits the acidic DNA cleavage of lens fibre nuclei. In addition, there must be another DNase implicated in the process which is not DNase I but appears to be a Ca2+, Mg2+ dependent molecule. Regulation of these DNase activities may be accomplished by the effect of post-translational modifications, acidic pH, mitochondrial release molecules, growth factors or oncogenes. Finally, fibre cells lose organelles without cytoplasmic elimination. The survival of these differentiated cells might be due to the action of survival factors such as FGF 1.
Animals↗
Helicobacter pylori in vivo causes structural changes in the adherent gastric mucus layer but barrier thickness is not compromised.
BACKGROUND: It has been proposed that a pathogenic effect of Helicobacter pylori is a weakening of the protective mucus barrier; however, this remains controversial. AIMS: To clarify the effects of H pylori infection on the mucus gel barrier in vivo. METHODS: Mucus gel polymeric structure and the thickness of the adherent mucus barrier were measured in endoscopic biopsy samples in subjects with and without H pylori infection. RESULTS: There was a significant 18% reduction in the proportion of polymeric gel forming mucin in the adherent mucus layer in H pylori positive compared with negative subjects. There was no change in the adherent mucus thickness between H pylori positive and negative subjects without gastric atrophy (mean (SD): 104 (26) micron, 106 (30) micron, respectively). There was however a significant reduction in mucus thickness in those H pylori positive subjects with underlying gastric atrophy (84 (13) micron, p=0.03) compared with those without atrophy. CONCLUSIONS: A partial breakdown in gel forming structure of the gastric mucus barrier does occur in H pylori infection per se but this is insufficient to cause a collapse of the mucus barrier.
Aged↗
Murine in vivo total body nitrogen by photoactivation.
A facility to measure total body nitrogen (TBN) by photoactivation analysis in rats, using the 14N(gamma, n)13N reaction, was designed, calibrated and evaluated. TBN provides a quantitative estimate of nutritional status. TBN in humans can be measured by neutron activation, however the small absolute amount of nitrogen in rats causes difficulties with this technique. Photoactivation analysis involved irradiating the specimen with high energy photons from an 18 MV Medical Linear Accelerator to a dose of approximately 2 Gy. The technique was calibrated using urea solution rat phantoms with 2.0-3.0% nitrogen content. By analysing the measured decay curve, the initial nitrogen count rate of 0.51 MeV photons was determined and the initial oxygen count rate, being an interfering source of 0.51 MeV photons, was shown to be constant. Within the range of nitrogen concentrations studied, the response is linear (r2 = 0.9) with a CV of 3.5%. Thus, photoactivation provides a relatively simple, in vivo technique for determining total body nitrogen in rats.
Animals↗
5-Fluorouracil-resistant colonic tumors are highly responsive to sodium butyrate/interleukin-2 bitherapy in rats.
Advanced colorectal cancer is generally refractory to 5-fluorouracil (5-FU) chemotherapy. This is linked to the emergence of resistant cell populations, probably due to a selection process. The identification of molecular markers and the improvement of alternative therapies thus remain important. We have used as an experimental model a rat colon cancer cell line (PROb), which exhibits features similar to those of the human situation. 5-FU treatment of rats bearing PROb tumors enhanced their survival but did not lead to cure. A PROb 5-FU-resistant subline (PRObR1) was obtained by continuous in vitro exposure to 5-FU. Resistance to 5-FU was accompanied by a 2-fold increase in thymidylate synthase activity and a substantially higher incorporation of thymidine in the presence of 5-FU, compared with parental PROb cells. Unexpectedly, in syngeneic rats, PRObR1 tumors exhibited delayed growth when compared with parental PROb tumors. This was ascribed to an increased sensitivity of PRObR1 cells to host immune response since no growth delay was observed in immunocompromised nude mice and since there was no detectable difference in proliferation rates between PROb and PRObR1 cells. 5-FU treatment was inefficient in prolonging the survival of rats bearing PRObR1 tumors. In contrast, an immunotherapeutic protocol combining sodium butyrate and recombinant interleukin-2 (NaBut/rIL-2) cured 80% of the rats bearing established PRObR1 tumors. Our results suggest that NaBut/rIL-2 treatment is efficient against 5-FU-chemoresistant rat colon cancer.
Animals↗
Wound cleansing...(continuing education credit).
This article aims to develop the nurse's understanding of wound cleansing, infection and colonisation, and includes a look at the use of topical and systemic antibiotics and topical antiseptics. It relates to UKCC professional development category: Care enhancement and Practice development.
Anti-Infective Agents, Local↗
Microbial biodegradation of organic wastes containing surfactants in a continuous-flow reactor.
In a continuous flow bioreactor seeded with microbes from municipal activated sludge, complete organic carbon oxidation of simulated graywater (wastewater produced in human residences, excluding toilet wastes) was achieved at dilution rates up to 0.36 h-1 in the presence of 64.1 microM linear alkylbenzenesulfonate (LAS) L-1. At LAS concentrations of 187 microM, the system functioned only at dilution rates up to 0.23 h-1, and the biomass yield was two-fold lower. There were physiological changes in the microbial communities under different operating conditions, as measured by specific contents of ATP and extracellular hydrolases as well as the respiratory potential of the biomass. LAS inhibited the activity of LAS-degrading microbes at >150 microM LAS, and the activity of other microbes at >75 microM LAS. Chemical analysis of graywater indicated that samples consisted primarily of biological polymers (proteins and polysaccharides) and lower concentrations of surfactants. Biological remediation of graywater is possible, although treatment efficiency is influenced by the operating conditions and wastestream composition.
Alkanesulfonates↗
Effects of Helicobacter pylori colonisation on the adherent gastric mucus barrier.
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Animals↗
Mucus and H. pylori.
A continuous, adherent mucus gel layer with mucosal bicarbonate secretion is the initial protective barrier in the stomach and duodenum against erosion by the gastric juice. H. pylori resides within the adherent mucus gel layer close to the epithelial surface. The barrier function of the mucus layer in vivo depends on (i) its thickness, and (ii) its gel structure, a property which is linearly dependent on the polymeric mucin content. We have shown in vivo that H. pylori colonisation alone did not decrease the thickness of the adherent gastric mucus barrier, although there was a mean 20% decrease in mucus thickness in those H. pylori positive subjects with underlying gastric atrophy. There was, however, a significant mean 18% reduction in the gel-forming polymeric mucin content of mucus from H. pylori subjects, independent of underlying atrophy. Studies in vitro suggest this loss of gel structure might arise from a H. pylori mediated, high local pH generated by urease activity rather than by proteolysis. This study shows that H. pylori infection alone does not compromise the overall integrity of the mucus barrier in vivo. However, in the immediate environment of the organism there appears to be a localised loss of mucus gel structure. The mucus barrier is compromised if H. pylori associated gastric atrophy or peptic ulceration follows.
Animals↗
Accumulation of NO synthase (type-I) at the neuromuscular junctions in adult mice.
Recent data have shown that NOS-I is localized almost exclusively to the sarcolemma of fast-twitch fibers, where it probably interacts with the dystrophin-glycoprotein complex. The concentration of dystrophin-related protein at the neuromuscular junctions and the possible involvement of NO in synaptic suppression led us to investigate the presence of NOS-I at the adult motor endplates. Our data clearly show that NOS-I protein, detected by immunohistochemistry accumulates at the adult endplates. Furthermore, the absence of NOS-I protein at the denervated neuromuscular junctions suggest a neural origin of this enzyme. The putative roles of NO at the endplate are discussed.
Animals↗
The neurotrophic activity of fibroblast growth factor 1 (FGF1) depends on endogenous FGF1 expression and is independent of the mitogen-activated protein kinase cascade pathway.
The expression of fibroblast growth factor (FGF) 1, a potent neurotrophic factor, increases during differentiation and remains high in adult neuronal tissues. To examine the importance of this expression on the neuronal phenotype, we have used PC12 cells, a model to study FGF-induced neuronal differentiation. After demonstrating that FGF1 and FGF2 are synthesized by PC12 cells, we investigated if FGF1 expression could be a key element in differentiation. Using the cell signaling pathway to determine the effects of FGF1 alone, FGF1 plus heparin, or a mutated FGF1, we showed an activation to the same extent of mitogen-activated protein (MAP) kinase kinase and MAP kinase (extracellular regulated kinase 1). However, only FGF1 plus heparin could promote PC12 cell differentiation. Thus, the MAP kinase pathway is insufficient to promote differentiation. Analysis of the PC12 cells after the addition of FGF1 plus heparin or FGF2 demonstrated a significant increase in the level of FGF1 expression with the same time course as the appearance of the neuritic extensions. Transfection experiments were performed to enhance constitutivly or after dexamethasone induction the level of FGF1 expression. The degree of differentiation achieved by the cells correlated directly with the amount of FGF1 expressed. The MAP kinase pathway did not appear to be involved. Interestingly, a 5-fold increase in FGF1 in constitutive transfected cells extended dramatically their survival in serum-free medium, suggesting that the rise of FGF1 synthesis during neuronal differentiation is probably linked to their ability to survive in the adult. All of these data demonstrate that, in contrast to the MAP kinase cascade. FGF1 expression is sufficient to induce in PC12 cells both differentiation and survival. It also shows that auto- and trans-activation of FGF1 expression is involved in the differentiation process stimulated by exogenous FGFs through a new pathway which remains to be characterized.
Adult↗
Biodegradation of organic wastes containing surfactants in a biomass recycle reactor.
The microbial biodegradation of simulated graywater, containing 21.5 mg of linear alkylbenzene sulfonate liter-1, was investigated with a continuous-flow bioreactor with 100% biomass recycle. Low concentrations of organic matter in the ultrafiltration eluate were achieved by hydraulic residence times as short as 1.6 h and for periods of up to 74 days at a hydraulic residence time of 6 h. Upon a shift from the chemostat to the biomass recycle mode, the increase in biomass with time approximated a linear rather than an exponential function. Biomass densities as high as 6.8 g of cell protein liter-1 were reached; this was 50-fold higher than the steady-state biomass level in chemostats fed the same medium. We assessed physiological changes in the microbial community after a switch from the chemostat to the biomass recycle mode. Over 150 h, there was a two- to fourfold decrease in the respiratory potential of the microbes. After this decrease, respiratory potentials were relatively constant up to 74 days of operation. A decline in reactivity was also indicated by increasing lag periods before growth in response to organic nutrient inputs and by a decrease in the proportion of cells able to reduce tetrazolium dye. However, the bioreactor system was still capable of rapidly metabolizing inputs of organic matter, because of the very high biomass concentrations. It appears that < 10% of the organic carbon inputs accumulate as biomass.
Bacteria↗
Paclitaxel sensitizes multidrug resistant cells to radiation.
The unique action of paclitaxel, to stabilize microtubules and block cells at the radiosensitive G2M phase of the cell cycle, suggests, it may sensitize tumors to radiotherapy. We have investigated the potential of this interaction to overcome multidrug resistance in vitro using the HL60 cell line and its P-glycoprotein expressing, multidrug resistant H/E8 subline. HL60 cells showed a modest 1.4-fold (p < 0.01) increase in sensitivity to 2 Gy radiation given 24 h after a 1 h treatment with paclitaxel. The H/E8 subline, which has increased radiation resistance and expresses an extended multidrug resistance phenotype, showed significant sensitization to radiation (up to 2.3-fold sensitization; p < 0.01) even with doses of paclitaxel which had no effect on cell viability or were associated with any G2/M block in the cell cycle. In the presence of verapamil, an inhibitor of P-glycoprotein mediated efflux, drug resistant cells could be sensitized to 2 Gy radiation by similar paclitaxel doses as the parental cell (> or = 30 nM; p < 0.01). These results indicate a therapeutic advantage may be possible in the treatment of resistant tumors by the combined use of paclitaxel with radiation.
Antineoplastic Agents, Phytogenic↗
Factorization versus duality in nonleptonic decays: A quark model approach.
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Journal Article↗
Gauge invariance and dimensional regularization with gamma 5 in flavor-changing neutral processes.
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Journal Article↗
Critical analysis of theoretical estimates for B-to-light-meson form factors and B--> psi K(K*) data using factorization.
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Journal Article↗
Seroprevalence of herpes simplex virus infections in a family medicine clinic.
OBJECTIVES: To determine the prevalence of herpes simplex virus (HSV) antibody in a general medical practice setting and to assess the frequency of subclinical infection. DESIGN: Prevalence study. SETTING: A family practice clinic at the University of Washington Medical Center, Seattle. PARTICIPANTS: Five hundred randomly selected patients between the ages of 18 and 45 years. MAIN OUTCOME MEASURES: Serum samples were tested by Western blot assay to detect the presence of antibody to HSV type 1 (HSV-1) and HSV-2. Demographic information and clinical history of oral and genital herpes were obtained. RESULTS: One hundred fourteen patients (23%) were seropositive for HSV-2 antibody, 277 patients (56%) were seropositive for HSV-1 antibody, 59 patients (12%) were seropositive for both HSV-2 and HSV-1 antibodies, and 163 patients (33%) were seronegative for both. Women were almost twice as likely as men to be seropositive for HSV-2 antibody (28% vs 15%, P < .001). Blacks had the highest rates of HSV-2 antibody seropositivity (60%) compared with whites (20%) and Asians (6%) (P < .001). Other demographic correlates of seropositivity included being older, having fewer years of education, and having public insurance. The specificity of a clinical history of genital herpes or sores for HSV-2 infection was high (99%), but the sensitivity was low (27%). CONCLUSIONS: Herpes simplex virus infection is common among patients seeking primary care. Women, blacks, and patients of lower socioeconomic status are most likely to be seropositive for HSV-2 antibody. The high frequency of unrecognized HSV infection has implications for primary care physicians in counseling patients regarding HSV infection and transmission.
Adult↗
The role of exogenous/endogenous basic fibroblast growth factor (FGF2) and transforming growth factor beta (TGF beta-1) on human corneal endothelial cells proliferation in vitro.
Adult human corneal endothelial cells (HCEC) have extremely low turnover rates but undergo rapid division in vitro when stimulated with soluble growth factors. We have investigated the role played by FGF2 and TGF beta-1 in the regulation of HCEC growth stimulation. HCEC from donors who were over 30 years old were cultured and experiments performed on cultures between the 2nd and the 6th passage in the presence of 5% NCS. Cell counts revealed a maximal stimulation of 2.1x for FGF2 and 1.9x for TGF beta-1 compared to control cultures. When both factors were added, a synergistic effect was noticed with a maximal stimulation of the proliferation rate of 4.5x over controls. In addition, endogenous FGF2 produced by HCEC was quantitated in a sensitive EIA assay. After 5 days in culture, 10(6) cells contained 150 ng FGF2 and 35 ng was extracted from trypsin-digested ECM. Two molar NaCl washes of ECM released 15.6 ng FGF2, which induced a slight mitogenic activity (1.5x over control) in HCEC cultures, which was partially inhibited by an anti-FGF2 antibody. Northern blot analysis of HCEC extracts revealed the presence of FGF receptors R1 and R2 mRNA. The bioactive FGFRs were demonstrated by the toxic effect of a mitotoxin FGF2-SAP. These results suggest that FGF2 could participate in the autocrine regulation of HCEC proliferation and survival. The synergy between exogenously added FGF2 and TGF beta demonstrates that a combination of different growth factors may be important to stimulate proliferation of these cells in vivo.
Adult↗