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Biomedical subjects

R J Doyle

Publications and source records attributed to R J Doyle.

18 recordsLinked to original sources
PubMed1979

Protection of sodium dodecyl sulfate-induced aggregation of concanalvalin A by saccharide ligands.

Concanavalin A is visibly aggregated by low concentrations of sodium dodecyl sulfate, maximum aggregation being obtained at pH 4.6. Other denaturants, such as urea, guanidine hydrochloride, Triton X-100, cetyltrimethylammonium bromide, Tween 80, and Brij 35 are ineffective in promoting visible aggregation. The sodium dodecyl sulfate-induced aggregation of concanavalin A requires the presence of an intact, saccharide-ligand binding-site. Rapid and complete reversal of the detergent effect was achieved by use of saccharides which bind to the lectin. Such compounds as tryptophan and o-nitrophenyl beta-D-galactopyranoside did not inhibit the aggregation of concanavalin A by sodium dodecyl sulfate, suggesting that the detergent does not bind the hydrophobic pocket on the surface of the protein. The results suggest that concanavalin A may have an additional, ligand-binding site which is metal-dependent and which can be modified by the addition of a saccharide ligand.

Chemical Phenomena↗
PubMed1979

Selective association of the chromosome with membrane in a stable L-form of Bacillus subtilis.

A stalbe L-form (Sal-1) of Bacillus subtilis was found to have retained a markedly modified chromosome-membrane association when compared to intact cells. The membrane-deoxyribonucleic acid complex of the L-form was similar to that of its parental strain in quantity and stability. Genetic analysis of the L-form membrane-deoxyribonucleic acid complex revealed enrichment for markers close to the replication origin, but not for internal markers, indicating preferential attachment of the origin of chromosomal replication to the membrane. These results are in close agreement with those found for the parental bacterial form. In contrast, the replication termius region was not preferentially attached to the membrane of the L-form, even though it is enriched in the bacterial form. The association of the chromosome with the membrane at the replication terminus does not appear to be necessary for cell growth and separation, but because the L-form divides aberrantly, it may be one of the factors required for normal deoxyribonucleic acid segregation and septation.

Bacillus subtilis↗
PubMed1979

Lectins in diagnostic microbiology: use of wheat germ agglutinin for laboratory identification of Neisseria gonorrhoeae.

A lectin slide agglutination test has been developed for the confirmatory identification of Neisseria gonorrhoeae. With wheat germ lectin as an agglutinin, 164 of 165 clinical isolates of N. gonorrhoeae gave a 3 to 4+ reaction within 6 to 8 min. Four gonococcal isolates, even though negative by the fluoresecent-antibody method, gave strong positive reactions with the wheat germ lectin. Among 23 isolates of Neisseria meningitidis tested, which included representatives of sero-groups A, B, C,D, X, Y, and Z, only one strain in group X gave a false-positive reaction. The nonpathogenic species of Neisseria, as well as Branhamella catarrhalis, all showed negative reactions with the wheat germ agglutinin. The novel method provides a simple, rapid, and inexpensive means for the laboratory diagnosis of gonorrhea and obviates the need for performing second-stage sugar fermentation studies or utilizing the more expensive fluorescent-antibody techniques.

Acetylglucosamine↗
PubMed1978

Histamine hypersensitivity in mice induced by concanavalin A.

This study compared the responses of CFW and CFI mice to concanavalin A (con A) and the histamine-sensitizing factor (HSF) of Bordetella pertussis. There were marked similarities between these two agents with regard to systems implicated in induced histamine sensitivity. Con A, like HSF, induces the sensitivity in CFW but not in CFI mice. The sensitizing agents both require the same time for optimum sensitization, both induce cutaneous sensitivities to histamine, and the mice are protected from the induced susceptibility of both agents by epinephrine and by desensitization with serotonin. They differed in that con A did not induce the systemic susceptibility to serotonin or to combined histamine and serotonin which is produced by HSF. The major difference related to mechanisms of action was the failure of con A to induce a systemic beta-adrenergic blockade, the block of which is manifested in HSF-treated CFW and CFI mice by the inhibition of an epinephrine-induced hyperglycemia. The resistance of beta-blocked CFI mice to histamine, and the susceptibility to histamine of the unblocked CFW mice sensitized with con A, is inconsistent with the theory that susceptibility results from a systemic adrenergic imbalance, but does not preclude a local adrenergic effect as the common element in histamine-sensitizing agents.

Animals↗
PubMed1977

Selective enrichment for genetic markers in DNA released by competent cultures of Bacillus subtilis.

Deoxyribonucleic acid is released into the growth medium by Bacillus subtilis at the time of competence. This DNA is enriched for the genetic markers which have previously been demonstrated to be elevated in membrane-DNA preparations and more recently in cell wall-DNA complexes. Furthermore, the purA16/leu-8 relative marker enrichment varies with time, reaching its highest point at the time of maximal competence. Enrichment remains elevated for at least 60 min further in the competence regimen. Thr results suggest that certain genetic markers of the B. subtilis chromosome are preferentially more available to the external medium as the development of competence proceeds.

Bacillus subtilis↗
PubMed1976

A mechanism for tobacco smoke-induced allergy.

Normal CFW mice, when exposed to tobacco smoke, showed a significantly increased susceptibility to the lethal effects of histamine. The LD50 for mice subjected to smoke was 45 mg/kg of histamine, whereas in normal CFW mice the LD50 was 1,100 mg/kg. The histamine susceptibility of smoked mice was markedly diminished by injecting the animals with isoproterenol. Normal CFW mice, as well as sham control mice, exhibited an epinephrine-induced hyperglycemia, whereas the blood glucose values for smoked mice given epinephrine were essentially the same as those for sham mice given only saline. This observation indicates that tobacco smoke may contain a component which causes an autonomic imbalance, hence rendering the mice more susceptible to histamine. This tobacco smoke-induced allergy is probably related to a blockade of adrenergic receptors and not to an immunologic phenomenon.

Adrenergic beta-Antagonists↗
PubMed1976

Inactivation of membrane transport in Escherichia coli by near-ultraviolet light.

Evidence is presented that near-ultraviolet (near-UV) light can alter galactoside transport in Escherichia coli in several independent ways. It can inactivate the permease system per se, it can interfere with metabolic energy production or transfer, and it can cause an increase in the generalized permeability of the membrane. Earlier publications suggested that near-UV destroys cofactors needed for electron transport and thus places a limitation on energy reserves. In agreement, we found that the active accumulation of [14C]thiomethyl-beta-D-galactopyranoside is decreased after irradiation by a larger factor than that due to action directly on the permease system. The effect on the latter was measured by the decrease in the rate of o-nitrophenyl-beta-D-galactopyranoside (ONPG) transport. As evidence that energy supplies for this "downhill" process did not become rate limiting after irradiation, we found that carbonylcyanide-m-chlorophenyl-hydrazone did not stimulate ONPG transport of irradiated cells. Cells genetically deficient in functional permease or cells treated with formaldehyde still transport ONPG passively, although at much lower rates. With the use of such cells, it was found that high fluences (doses) made the cells leaky. Further evidence that the permease system and the metabolic energy system can be inactivated independently is also presented. It is shown that a photoproduct from the irradiation of chloramphenicol inactivates the permease system much more efficiently than the energy system. In addition, it is shown that thio-beta-D-digalactopyranoside protects the permease system, but not the energy system, both against direct inactivation by near-UV and against photosensitized inactivation in the presence of chloramphenicol.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
PubMed1976

A circular test pattern for evaluating x-ray tube focal spots.

The design and use of a circular x-ray resolution test pattern is presented. This pattern is shown to yield equivalent focal spot dimensions equal to those obtained with the more commonly used star pattern. The advantage of using the circular pattern is that it obviates the necessity of positioning the pattern strictly along the x-ray beam central axis. A major source of experimental error in making focal spot measurements is therefore circumvented, especially in the case of x-ray tubes with a small target angle.

Mathematics↗
PubMed1975

Organization of teichoic acid in the cell wall of Bacillus subtilis.

The phytohemagglutinin, concanavalin A (Con A), interacts specifically and reversibly with the polyglucosyl glycerol phosphate teichoic acid of Bacillus subtilis 168 cell walls. Advantage has been taken of this interaction to examine the organization of the surface teichoic acid at the ultrastructural level. Con A-treated whole cells and cell walls contain an irregular, fluffy layer 25 to 60 nm thick which is absent in untreated or alpha-methyl glucoside-treated preparations. This discontinuous layer is present only on the outer profile of Con-A-treated cell walls. The surface teichoic acid is proposed to be oriented perpendicular to the long axis of the cell. Fixation and embedment for electron microscopy result in condensation of this layer which then contributes to the stainable portion of the wall. Con A treatment binds adjacent teichoic acid molecules in their native configuration producing the irregular, fluffy layer visualized.

Bacillus subtilis↗
PubMed1975

Distribution of teichoic acid in the cell wall of Bacillus subtilis.

Hydrolysis of the cell wall of Bacillus subtilis 168 by autolysins or lysozyme resulted in the exposure of glucosylated teichoic acid molecules as evidenced by increased precipitation of [14C] concanavalin A. The number of concanavalin A-reactive sites increased significantly after only limited enzymatic digestion of the walls. Quantitative analyses of [14C] concanavalin A-treated wall or wall hydrolysate complexes indicate that approximately one-half of the teichoic acid molecules are surface-exposed, whereas the remainder are probably embedded within the peptidoglycan matrix. Treatment of the cell walls with sodium dodecyl sulfate or Triton X-100 did not result in new concanavalin A-reactive sites. Partial autolysis diminished the ability of the cell walls to adsorb bacteriophage phi25. Fluorescein-labeled concanavalin A bound intensely over the entire surface of growing B. subtilis 168 cells, suggesting that teichoic acid molecules are located on the total solvent-exposed surface area of the bacteria.

Adsorption↗
PubMed1975

Soluble macromolecular complexes involving bacterial teichoic acids.

Cell wall and membrane teichoic acids from several bacteria formed soluble complexes with polysaccharides and bovine plasma in alkyl alcohol solutions. Polysaccharides which contain different monomeric units and anomeric configurations complexed with the teichoic acids, suggesting that the interaction is relatively nonspecific. Teichoic acids complexed glycogen or bovine plasma albumin in 50 to 97% ethanol solutions. The macromolecular association between teichoic acids and polysaccharides or proteins was independent of teichoic acid size over a threefold molecular weight range. Glycerol phosphates or an acid hydrolysate of teichoic acid would not complex to either glycogen or bovine plasma albumin in ethanol. The optimal interaction between glycogen and the Bacillus subtilis lipoteichoic acid occurred between pH 4.5 and 8.2. The ability of teichoic acids to bind polysaccharides and proteins in moderate dielectric constant solvents suggests that these polymers may serve as complexing agents for hydrophilic molecules found in membranes.

Bacillus subtilis↗