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Biomedical subjects

J Mathews

Publications and source records attributed to J Mathews.

At least 91 records · Page 5Linked to original sources
PubMed1983

Antibiotic-induced modification of Bacteroides fragilis and its susceptibility to phagocytosis by human polymorphonuclear leukocytes.

Bacteroides fragilis grown in the presence of sub-inhibitory concentrations of clindamycin was shown to be altered its degree of encapsulation and susceptibility to phagocytosis by human polymorphonuclear leukocytes. Little polysaccharide capsule could be demonstrated either by light or transmission electron microscopy when the bacteria were grown anaerobically for four hours in the presence of 1/2 MIC of clindamycin. Such clindamycin-grown cells could be opsonized by normal human serum, and although less complement was consumed in the process, were more effectively taken up by the leukocytes than bacteria grown in the absence of the drug (45% versus 24%). It was also shown that drug treatment caused significant cellular leakage in the presence of serum, the 3H-label appearing extracellularly. In addition there was greater loss of viability of the bacterial cells grown in the presence of the drug and subsequently exposed to the leukocytes for 60 min.

Bacteroides fragilis↗
PubMed1981

Potentiation of opsonization and phagocytosis of Streptococcus pyogenes following growth in the presence of clindamycin.

Streptococcus pyogenes, bearing M-protein on its surface, resists opsonization by normal human serum and subsequent phagocytosis by human polymorphonuclear leukocytes. Previous studies have shown that M-protein positive organisms are poorly opsonized by the alternate pathway of complement. In an attempt to define further the role of the surface components of S. pyogenes in this process, we examined the ability of clindamycin, an antibiotic that inhibits protein biosynthesis, to alter bacterial opsonization. An M-protein positive strain of S. pyogenes was grown in varying concentrations of clindamycin at levels lower than those which inhibited growth, i.e., at levels less than the minimal inhibitory concentration. These bacteria were incubated with purified human polymorphonuclear leukocytes and peripheral blood monocytes. Significant enhancement of bacterial opsonization, phagocytosis, and killing resulted. Measurement of complement consumption and binding of the third component of complement (C3) onto the bacterial surface demonstrated that organisms grown in the presence of clindamycin activated complement more readily and fixed more C3 on their surface. Electron microscopy revealed the probable basis for these findings. Streptococci exposed to clindamycin during growth were largely denuded of surface "fuzz," the hairlike structures bearing M-protein. We conclude that the incorporation of clindamycin at concentrations that fail to inhibit growth of S. pyogenes nevertheless causes significant changes in the capacity of these bacteria to resist opsonization by serum complement. These findings support the hypothesis that M-protein inhibits bacterial opsonization by interfering with effective complement activation on the bacterial surface.

Antigens, Bacterial↗
PubMed1978

Effect of 1-(2,4-dichlorobenzyl)-indazole-3-carboxylic acid on sperm tails in rhesus monkeys.

Large numbers of spermatozoa with bent or coiled tails were found in the ejaculates of rhesus monkeys treated with 1-(2,4-dichlorobenzyl-indazole-3-carboxylic acid (DICA) (50 or 500 mg/kg for various periods). The defect appeared only in spermatozoa in the cauda epididymidis and consisted of axoneme disarrangement and loss of the fibre doublets. The coil was completely enclosed in a membrane.

Animals↗
PubMed1976

Pathogenesis of herpes simplex virus types 1 and 2 in mice after various routes of inoculation.

The pathogenesis of herpes simplex virus (HSV) types 1 and 2 was compared after inoculation of mice by different routes. Intravaginal inoculation of HSV-1 and HSV-2 produced a local infection, with virus recovery from the vagina through 5 days. Virus was recovered from the spinal cords 4 to 5 days after inoculation but not from liver, kidney, lung, spleen, or blood. Intravenous or intraperitoneal inoculation of HSV-2 produced a focal necrotic hepatitis similar to that described previously (S. C. Mogenson, B. Teisner, and H.K. Andersen, 1974). The viral etiology of the liver lesions was confirmed by virus isolation (through 4 days) and electron microscopy. No evidence of infection of the kidney, lung, blood, or spleen was observed, although virus was isolated from spinal cord homogenates 7 days after inoculation. HSV-1 inoculation by the intraperitoneal or intravenous route resulted in virus isolation from the kidney during the 7-day harvest period, without producing overt pathological changes. Virus was isolated from spinal cord homogenates 2 to 3 days after HSV-1 inoculation but not from homogenates prepared from spleen, lung, or blood. Increases in serum transaminase activity were observed after systemic (intravenous) inoculation of HSV-2 but not after HSV-1 inoculation.

Alanine Transaminase↗
PubMed1971

Classification of Streptomyces spore surfaces into five groups.

Streptomyces spores surfaces have been classified into five groups, smooth, warty, spiny, hairy, and rugose, by examination of carbon replicas of spores with the transmission electron microscope and by direct examination of spores with the scanning electron microscope.

Carbon↗
PubMed1970

Centrifugal sedimentation of virus particles for electron microscopic counting.

Centrifuge cells with conical chambers were provided by using special inserts for the stainless-steel tubes that fit the Spinco SW-39 rotor. Particulate material, centrifuged in these cells, was collected on carbon-coated glass discs. These discs were exposed to OsO(4) vapor, dehydrated in graded alcohols, air-dried, and metal-shadowed. The metal-shadowed carbon film was floated from the glass, mounted on a grid, and examined. A knowledge of cell geometry and microscope magnification allowed correlation of the number of particles observed to a volume of the original suspension. A precision of +/-6% at the 95% confidence level was attained when counting approximately 100 particles per 10,000 x field. Applications and advantages of the method are discussed.

Centrifugation↗
PubMed1968

Thallium poisoning.

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Diagnosis, Differential↗
PubMed1968

Microtiter indirect hemagglutination procedure for identification of streptococcal M-protein antibodies.

A number of investigators have attempted to utilize the hemagglutination system for detection of streptococcal type-specific antibody in human sera. Cross-reactions have made the procedure unreliable without cumbersome and time-consuming manipulation of the test sera. A method is described in which a microtiter indirect hemagglutination technique, using sensitized sheep erythrocytes, is sensitive, specific, and reliable for titration of type-specific antibody after naturally acquired or induced streptococcal infection.

Animals↗
PubMed1968

Taxonomy by carbon replication. II. Examination of eight additional cultures of Streptomyces hygroscopicus.

Carbon repligraphic comparison of eight cultures described as Streptomyces hygroscopicus showed four distinct types. Five of the cultures could be considered S. hygroscopicus by spore type (a relatively nonsegmented spore structure with an extremely wrinkled surface); three of the cultures had spore types that differed from one another and from the hygroscopicus holotype. Differentiation was confirmed by Ektacolor pattern.

Histological Techniques↗