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Biomedical subjects

H W Larsh

Publications and source records attributed to H W Larsh.

At least 37 records · Page 2Linked to original sources
PubMed1977

In vivo and in vitro cell-mediated immune responses to a cell wall antigen of Blastomyces dermatitidis.

An alkali-soluble, water-soluble cell wall fraction of Blastomyces dermatitidis, designated B-ASWS, was evaluated as an antigen for detecting in vivo (skin tests) and in vitro migration inhibition factor (MIF) production and lymphocyte transformation (LT) responses in Blastomyces-infected guinea pigs. The biological activity of B-ASWS was compared with that of blastomycin KCB-26. The superiority of B-ASWS, in terms of its sensitivity and specificity, was evident in in vivo and in vitro assays. Skin tests responses were obtained in 21 of the 24 Blastomyces-infected guinea pigs, whereas only one of the 14 Histoplasma-infected guinea pigs were significantly greater than those obtained using cell populations from Histoplasma-infected or noninfected guinea pigs. The con-MIF and LT in peritoneal exudate cells and lymph node cells of homologuosly infected animals. In each biological system, the response of the Blastomyces-infected guinea pigs were significantly greater than those obtained using cell populations from Histoplasma-infected or non-infected guinea pigs. The contrasting efficacy of B-ASWS as compared with blastomycin KCB-26, suggests that the cell wall antigen will be a useful tool for detecting cell-mediated immune responses in blastomycosis.

Animals↗
PubMed1977

Enumerative fluorescent vital staining of live and dead pathogenic yeast cells.

A quantitative technique is presented for differentiating live and dead yeast cells grown in culture through the use of the fluorescent dye acridine orange. The method gives results that correlate well with those of other commonly used vital staining techniques and is free of certain interpretative errors inherent in them. Vital staining of yeasts with acridine orange also allows for more precise assessment of the physiological state of individual cells and the culture as a whole. The progressive senescence of yeast cells in culture can be monitored by the changing staining characteristics of several subcellular organelles. The method is simple and reliable.

Acridines↗
PubMed1977

Accidental inoculation blastomycosis.

The pathogenesis of blastomycosis as a primary pulmonary infection has been well established and widely accepted. The rate cases of primary cutaneous inoculation are in all documented instances related to "laboratory" accidents. A case of inoculation with a culture suspension of Blastomyces Dermatitidis is herein reported. A slow healing chancre remained active for about eight months.

Accidents, Occupational↗
PubMed1976

In vitro and in vivo activity of 2,4-diamino-6-(2-(3,4-dichlorophenyl)acetamido) quinazoline against Cryptococcus neoformans.

The minimum inhibitory concentration of quinazoline derivative was determined by the tube dilution method for Cryptococcus neoformans, strain 184. The effect of this chemical agent on macromolecular metabolism indicated an inhibition of incorporations of labeled precursors into RNA and protein of C. neoformans. A mouse model infection with C. neoformans was established. Following this, the animals were given ip or oral doses of different concentrations of the experimental drug. Infected mice responded to ip administration of the drug in that the percentage of surviving mice increased progressively with increasing drug dosage. The curing dose 50 (CD50) was determined, based on the isolation of C. neoformans from organs of animals during or at the termination of the experiments.

Antifungal Agents↗
PubMed1976

A study on transformation in a mutant of Candida pseudotropicalis.

This paper reports on the possible influence of various factors on the frequency of transformation in Candida pseudtropicalis. The concentration of DNA used varied between 25 mug and 100 mug/ml. The maximum percentage transformation 0-16% occured at 75 mug/ml.

Candida↗
PubMed1975

Qualitative and quantitative assay of trichothecin: a mycotoxin produced by Trichothecium roseum.

A method for quantitative determination of trichothecin in crude culture filtrates was presented. The method utilized an agar diffusion bioassay against Candida albicans, a colorimetric test involving a halochromatic reaction with sulfuric acid, and subsequent formation of blue color with methanol, and thin-layer chromatography of trichothecin and its dinitrophenylhydrazine derivative. A positive result in all three systems confirmed the presence of trichothecin. Quantitative results were generally in close agreement.

Analysis of Variance↗
PubMed1975

Chromatographic separation of pigments produced by Arthroderma benhamiae.

Variations in pigment production under different cultural conditions have limited the usefulness of pigmentation for identifying strains of Arthroderma benhamiae. If culture conditions are constant, pigmentation by individual strains is reproducible, and may be extracted and separated by thin layer chromatography. This allows recognition of pigment similarities which may be masked in whole colonies, thereby greatly enhancing the value of pigmentation in strain identification.

Acetone↗
PubMed1974

Immunocytoadherence during experimental histoplasmosis.

Immunocytoadherence was investigated as a method of detecting active histoplasmosis in two groups of infected New Zealand white rabbits. Yeast-phase Histoplasma capsulatum was given intravenously to one group and intratracheally to the other. There was a striking correlation between the clinical condition of the animals and the number of rosettes seen. This number increased as the infection progressed and decreased as it regressed. The immunocytoadherence technique might be of value in detecting active histoplasmosis, and investigation in humans is warranted.

Animals↗
PubMed1974

Isolation of skin test-active preparations from yeast-phase cells of Blastomyces dermatitidis.

Cell wall and cytoplasmic fractions were isolated from mechanically disrupted yeast-phase cells of Blastomyces dermatitidis in an effort to obtain a reliable skin-test antigen. The biological activities of these fractions were compared with those of two blastomycin preparations. The cytoplasmic antigens exhibited a low index of specificity yet exceeded the specificities of the blastomycins. The skin test-active component(s) of the cytoplasmic material had a molecular weight between 10,000 and 30,000 and could easily be concentrated by ultrafiltration on a PM-10 membrane. Unlike the cytoplasmic antigens and blastomycins, an alkali-soluble, water-soluble cell wall antigen effectively distinguished guinea pigs that were sensitized to B. dermatitidis from those sensitized to Histoplasma capsulatum. The biological activity of the yeast-phase antigen could be quantitated, on a weight basis, after purification by ultrafiltration (PM-10 membrane).

Animals↗
PubMed1974

Yeast- and mycelial-phase antigens of Blastomyces dermatitidis: comparison using disc gel electrophoresis.

The disc gel electrophoretic patterns obtained with skin test-active (mycelial and yeast) antigens of Blastomyces dermatitidis were compared. As would be expected, the blastomycins (mycelial-phase) and the cytoplasmic ultrafiltrates (yeast-phase) were heterogeneous mixtures containing proteins, glycoproteins, lipoproteins, and carbohydrates. The skin test-active cytoplasmic ultrafiltrates and the blastomycins contained glycoproteins that had similar R(f) values which allows the possibility that one or more of these components is responsible for the skin-test reactivity of these antigens. The electrophoretic migration of the alkali-soluble, water-soluble cell wall antigen differed from those of the cytoplasmic antigens and the two blastomycins. Electrophoresis, Sephadex chromatography, and ultrafiltration studies showed that the alkali-soluble, water-soluble cell wall antigen is comprised of lipid, polysaccharide, and protein and has a molecular weight range of 30,000 to 50,000. The increased number and mobility of both the protein and carbohydrate bands after denaturation and electrophoresis of this antigen in sodium dodecyl sulfate indicate that there are several cross-linkages between the polysaccharide and/or protein moieties, possibly via lipid or disulfide bridges.

Antigens, Fungal↗
PubMed1974

Skin testing of guinea pigs and footpad testing of mice with a new antigen for detecting delayed hypersensitivity to Cryptococcus neoformans.

This study was undertaken to evaluate the potential of a cryptococcal culture filtrate antigen, cryptococcin C184, for detecting delayed hypersensitivity in Cryptococcus neoformans-injected animals. The antigen was tested on guinea pigs which had received saline or C. neoformans and on animals sensitized to Histoplasma capsulatum, Blastomyces dermatitidis, Candida albicans, or Sporothrix schenckii. A delayed-type hypersensitivity response was elicited by cryptococcin C184 in C. neoformans-injected guinea pigs, whereas no indurations or erythemas were seen at 48 h after skin testing of saline controls or heterologously sensitized guinea pigs. Besides being specific for Cryptococcus, the antigen showed a high degree of sensitivity and was reproducible. Footpad tests were conducted with the antigen on mice which had previously received either 10(5) viable C. neoformans cells or saline. Delayed hypersensitivity was indicated in the C. neoformans-injected mice by the increase in thickness of antigen-injected footpads when compared with the saline-injected footpads. In control mice, antigen- and saline-injected footpads were comparable in thickness 24 h after injection. Mice sensitized to B. dermatitidis were footpad tested with C184, and no cross-reactivity was demonstrated.

Agglutination Tests↗