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Biomedical subjects

A R Smith

Publications and source records attributed to A R Smith.

At least 127 records · Page 7Linked to original sources
PubMed1986

A nystatin-resistant mutant of Saccharomyces cerevisiae: isolation and characterization by electron microscopy and chemical analysis of whole cells, cell-walls and protoplasts.

A mutant of Saccharomyces cerevisiae NCYC 239 with a high minimum inhibitory concentration (35 micrograms ml-1) for nystatin, compared to that of the parent strain (2 micrograms ml-1), was derived by a series of subcultures in media containing increasing antibiotic concentrations. In the absence of nystatin, the growth rate of the mutant was significantly lower than the parent strain, although mean cell-size and size-distribution were similar. No differences between strains were detectable by electron microscopy. Analysis of whole cells showed the total sterol present and the ratio of ergosterol:24(28)dehydroergosterol was similar. However, there were marked differences in amino acid content and chain-length of fatty acids in the cell wall, and protoplasts from resistant cells had decreased amounts of unsaturated fatty acids. It is suggested that alterations in cell wall components in the mutant may be directly linked to the mechanism of nystatin resistance.

Amino Acids↗
PubMed1986

Uptake of nystatin by sensitive and resistant cells of Saccharomyces cerevisiae.

The uptake of nystatin by sensitive and by resistant cells of Saccharomyces cerevisiae was studied as a function of nystatin concentration, temperature and pH. The presence or absence of glucose in nystatin uptake experiments was also studied. The rate data, effects of glucose and the derived activation energies for nystatin uptake revealed significant differences in response between sensitive and resistant cells. The role of the cell wall in the uptake process is discussed.

Drug Resistance, Microbial↗
PubMed1986

Endotoxin-induced bovine mastitis: immunoglobulins, phagocytosis, and effect of flunixin meglumine.

Milk whey immunoglobulins (Ig) and phagocytosis of staphylococci by milk polymorphonuclear neutrophilic leukocytes (PMN) were measured in 12 cows (allotted to 6 pairs) during acute bovine mastitis induced by intramammary inoculation of endotoxin. Six of these cows (or 1 in each pair) were treated with flunixin meglumine and were compared with the others (given only saline solution). The endotoxin inoculation comprised 10 micrograms of Escherichia coli O26:B6 lipopolysaccharide injected into one of the rear quarters (mammae). Flunixin meglumine was administered parenterally at a dosage of 1.1 mg/kg every 8 hours (total of 7 doses) beginning at 2 hours after endotoxin was injected. Milk samples were obtained, and whey samples were prepared from each quarter of each cow 3 times before inoculation and at 2, 4, 8, 12, 24, 48, 72, 96, 120, 144, 168, and 336 hours after endotoxin was inoculated. Significant increases (P less than 0.05) in milk whey IgG1, IgG2, IgM, and IgA concentrations were observed in whey samples from endotoxin-inoculated quarters. Greatest relative increase was seen for IgG2. Increased whey Ig concentrations were not observed in quarters which were not inoculated with endotoxin. Concentrations of whey IgG1 and IgM in endotoxin-inoculated quarters were significantly (P less than 0.05) decreased in flunixin meglumine-treated cows, compared with those in saline solution-treated cows. Significant increases in phagocytosis of staphylococci by milk PMN were observed in whey samples from endotoxin-inoculated quarters. Significant differences in PMN phagocytosis were not found in whey samples from cows given flunixin meglumine when compared with whey samples from cows given saline solution.

Analysis of Variance↗
PubMed1986

Uptake of nystatin by protoplasts of sensitive and resistant cells of Saccharomyces cerevisiae.

The uptake of nystatin by protoplasts derived from sensitive and resistant cells of Saccharomyces cerevisiae has been studied as a function of nystatin concentration, temperature and pH. The presence or absence of glucose in the uptake experiments was also studied. Activation energies (Ea) for nystatin uptake revealed profound differences between protoplasts derived from sensitive and resistant cells. Those for the latter closely resembled their whole cell counterparts. The values of Ea for the uptake of nystatin under all the conditions studied indicate the importance of the cell wall in the uptake process.

Biological Transport↗
PubMed1985

Structure of the sidechain of lipopolysaccharide from Pseudomonas syringae pv. morsprunorum C28.

The sidechain of the lipopolysaccharide from the phytopathogen Pseudomonas syringae pv. morsprunorum C28 was shown to be composed of D-rhamnose. Using 1H and 13C-NMR spectroscopy, methylation analysis, Smith degradation and optical rotation data, the repeat unit was found to have the structure: ----3)-D-Rhap-(alpha 1----3)-D-Rhap-(alpha 1----2)-D-Rhap-(alpha 1---- and a degree of polymerization of approximately 70. Attention is drawn to the possible prevalence of D-6-deoxyhexoses in the lipopolysaccharides of plant pathogenic bacteria.

Carbohydrate Conformation↗
PubMed1985

Limb preservation in replantation surgery.

Five patients are presented in whom a traumatically amputated extremity or digit was perfused with oxygenated Fluosol DA-20%. Perfusion lasted between 16 and 46 hours. Microcirculatory oxygenation was monitored using pO2 measurements. Moreover, K¿lactate, glucose, and ATP levels were measured and electron microscopic sections of the vessels were investigated at the end of the experiment. All above-mentioned parameters suggest that the tissue was sufficiently provided with oxygen and viable after many hours of perfusion. Conclusive evidence of the viability of a perfused digit was given by its successful replantation after 17 hours of Fluosol perfusion (at approximately 15 degrees C).

Adenosine Triphosphate↗
PubMed1985

Experimental porcine eperythrozoonosis: T-lymphocyte suppression and misdirected immune responses.

Immune responses and hematologic alterations were investigated in splenectomized pigs after IM inoculation with Eperythrozoon suis. Early hematologic alterations were massive parasitism of RBC, severe hypoglycemia, moderate bilirubinemia, and mild anemia; later findings included severe anemia, minimal parasitism of RBC, spontaneous agglutination of RBC at 25 C and 4 C which was reversible at 37 C, transient thrombocytopenia, and mild bilirubinemia. The humoral immune responses consisting of a transitory hyperglobulinemia and increase of indirect hemagglutination (IHA) titers against E suis were attributed to immunoglobulin M cold agglutinins. Cell-mediated immune responses, measured by phytohemagglutinin- and pokeweed mitogen-induced lymphocyte blastogenesis, were reduced after massive parasitemia. Blastogenesis induced by Escherichia coli lipopolysaccharide mitogen was increased before the hyperglobulinemia and an increase in IHA titer. There was an increase in the uptake of [3H]thymidine by lymphocytes cultured without mitogens after the decline in total globulin concentration and IHA titer.

Anaplasmataceae Infections↗
PubMed1985

Arachidonic acid metabolites in milk of cows during acute coliform mastitis.

Concentrations of prostaglandin F2 alpha (PGF2 alpha) and thromboxane B2 (TXB2) were evaluated in the milk of cows with naturally occurring (n = 3) and experimentally induced (n = 5) acute coliform mastitis. These arachidonic acid metabolites were measured by radioimmunoassay in unextracted milk. Experimental infections were induced by inoculating 600 to 1,200 colony-forming units of Escherichia coli into 1 mammary quarter per experimental cow. In the experimental cows, milk was collected before inoculation and at 12, 24, 36, 48, 60, and 72 hours after inoculation. Somatic cell concentrations, bovine serum albumin, and concentrations of PGF2 alpha and TXB2 were determined in milk collected at each sampling. Mild-to-moderate increases in milk PGF2 alpha and TXB2 concentrations were observed in cows with naturally occurring mastitis. the increases corresponded to the clinical severity and course of mastitis. In the experimental cows, increases in milk PGF2 alpha and TXB2 concentrations were observed, but the increases were not significant, using a statistical model that included factors of treatment, cows, hours after inoculation, cows-by-treatment and hours-by-treatment interactions, and random error (residual). Results of the present study indicated a large biological variability in milk arachidonic acid metabolite concentrations in cows with acute coliform mastitis, and that arachidonic acid metabolites may be important in the pathophysiologic process of acute coliform mastitis.

Acute Disease↗
PubMed1985

The free latissimus dorsi flap in reconstructive microsurgery.

The results are described of coverage of skin defects of the leg, foot and hand by use of a free vascularized musculocutaneous latissimus dorsi flap in 32 patients with previously incurable defects. Also presented are the case reports of three representative patients. The results show a success rate of 90%, with thrombosis of either the arterial or venous anastomoses as the only complications. Adequate postoperative screening (t.c. pO2, temperature, etc.) leads to early discovery of this thrombosis, after which revision can save the flap.

Adult↗
PubMed1984

The origin of the oxygen incorporated during the dehalogenation/hydroxylation of 4-chlorobenzoate by an Arthrobacter sp.

An Arthrobacter sp. has been shown to dehalogenate 4-chlorobenzoate yielding 4-hydroxybenzoate. Experiments with 18O indicate that, in the presence of cell-free extracts, the hydroxyl group which is substituted onto the aromatic nucleus during dehalogenation is derived from water and not from molecular oxygen. Dehalogenation therefore is not catalysed by a mixed-function oxidase; instead a novel aromatic hydroxylase is implicated in the reaction.

Arthrobacter↗
PubMed1984

Pion treatment procedures and verification techniques.

Procedures and techniques developed for the negative pi-meson (pion) radiotherapy program at the Los Alamos Meson Physics Facility, Los Alamos, NM, are reviewed and described. A particular pion patient is followed through the entire planning and treatment sequence to describe CT scanning procedures, bolus and collimator and treatment techniques developed to minimize positioning errors (less than 5 mm). Comparison of 2-D and 3-D isodose calculations developed at Los Alamos showed differences of less than 10% attributable to multiple scattering effects and the computational models used. Treatment verification methods using in vivo ion chamber dosimetry generally confirmed the prescribed dose delivery within 10% and using TLD within 18%.

Elementary Particles↗
PubMed1984

A structural investigation of the Epstein-Barr (EB) virus membrane antigen glycoprotein, gp340.

Epstein-Barr (EB) virus membrane antigen (MA) glycoprotein (gp340) purified by a molecular weight-based technique has been subjected to biochemical analysis. Following treatment with glycosidases or tunicamycin during synthesis, the carbohydrate moiety was found to be made up of both O-linked and N-linked types and to constitute about 50% of the molecular mass. Digestion studies with neuraminidase and oligosaccharidase have indicated that the molecule is heavily sialated with most of the sialic acid located on the O-linked sugars. The high carbohydrate content of gp340 appears to confer resistance to proteolysis; thus, V8 protease was only effective at concentrations above 1 mg/ml when three large fragments of mol. wt. 330K, 190K and 160K were generated. Removal of sialic acid before V8 protease digestion did not alter this pattern nor affect the antigenicity of the digestion fragments. Antigenicity of the intact molecule was likewise unaffected by removal of sialic acid nor were the O-linked and N-linked carbohydrate moieties essential for this property. The binding of virus-neutralizing human sera and monoclonal antibody by gp340 from which either O-linked or N-linked sugars had been removed seems to indicate that the sites on the molecule that generate the neutralizing antibodies are present in the protein component. The significance of these results is discussed in relation to the development of a subunit vaccine against EB virus.

Animals↗
PubMed1984

Degradation of 4-Chlorobenzoic Acid by Arthrobacter sp.

A mixed population, enriched and established in a defined medium, from a sewage sludge inoculum was capable of complete mineralization of 4-chlorobenzoate. An organism, identified as Arthrobacter sp., was isolated from the consortium and shown to be capable of utilizing 4-chlorobenzoate as the sole carbon and energy source in pure culture. This organism (strain TM-1), dehalogenated 4-chlorobenzoate as the initial step in the degradative pathway. The product, 4-hydroxybenzoate, was further metabolized via protocatechuate. The ability of strain TM-1 to degrade 4-chlorobenzoate in liquid medium at 25 degrees C was improved by the use of continuous culture and repeated sequential subculturing. Other chlorinated benzoates and the parent compound benzoate did not support growth of strain TM-1. An active cell extract was prepared and shown to dehalogenate 4-chloro-, 4-fluoro-, and 4-bromobenzoate. Dehalogenase activity had an optimum pH of 6.8 and an optimum temperature of 20 degrees C and was inhibited by dissolved oxygen and stimulated by manganese (Mn). Strain improvement resulted in an increase in the specific activity of the cell extract from 0.09 to 0.85 nmol of 4-hydroxybenzoate per min per mg of protein and a decrease in the doubling time of the organism from 50 to 1.6 h.

Journal Article↗
PubMed1984

Evaluation of a surfactant mixture C31G as a teat dip by a modified excised teat model.

A mixture of amphoteric surfactants with antimicrobial properties, C31G, was evaluated as a teat dip by a modified excised teat model. The model was modified to avoid misinterpretation of results from indigenous bacterial microflora on teats. In three experiments, bacterial numbers recovered from teats dipped in .75, 1.5, and 3.0% solutions of C31G were compared with bacteria recovered from undipped teats (negative controls) and teats dipped with 1.0% iodophor (an effective teat dip). Mean log reductions of teat end concentrations of Staphylococcus, aureus, Streptococcus fecalis, and Escherichia coli were determined in each experiment. Efficacy was greatest for the 3.0% solution of C31G with mean log reductions (Log reduction = Log 10 of controls - Log 10 of dipped teats) 3.53 for Staphylococcus aureus, 2.89 for Streptococcus fecalis, and 3.16 for Escherichia coli. Iodophor (1%) yielded mean log reductions of 3.26 for Staphylococcus aureus, 2.16 for Streptococcus fecalis, and 2.83 for Escherichia coli. For all three organisms, number of viable organisms decreased with increasing concentrations of C31G. The efficacy of C31G should be evaluated in vivo.

Animals↗