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Biomedical subjects

L S Cronholm

Publications and source records attributed to L S Cronholm.

11 recordsLinked to original sources
PubMed1984

Bacteria associated with crabs from cold waters with emphasis on the occurrence of potential human pathogens.

A diverse array of bacterial species, including several potential human pathogens, was isolated from edible crabs collected in cold waters. Crabs collected near Kodiak Island, Alaska, contained higher levels of bacteria than crabs collected away from regions of human habitation. The bacteria associated with the crabs collected near Kodiak included Yersinia enterocolitica, Klebsiella pneumoniae, and coagulase-negative Staphylococcus species; the pathogenicity of these isolates was demonstrated in mice. Although coliforms were not found, the bacterial species associated with the tissues of crabs collected near Kodiak indicate possible fecal contamination that may have occurred through contact with sewage. Compared with surrounding waters and sediments, the crab tissues contained much higher proportions of gram-positive cocci. As revealed by indirect plate counts and direct scanning electron microscopic observations, muscle and hemolymph tissues contained much lower levels of bacteria than shell and gill tissues. After the death of a crab, however, the numbers of bacteria associated with hemolymph and muscle tissues increased significantly. Microcosm studies showed that certain bacterial populations, e.g., Vibrio cholerae, can be bioaccumulated in crab gill tissues. The results of this study indicate the need for careful review of waste disposal practices where edible crabs may be contaminated with microorganisms that are potential human pathogens and the need for surveillance of shellfish for pathogenic microorganisms that naturally occur in marine ecosystems.

Alaska↗
PubMed1984

Bacterial transmigration as an indicator of time of death.

Time of death is difficult to evaluate in many forensic science situations. We have developed an animal model for assessing the time of death by evaluating the transmigration of normal microbiota through the wall of the small intestine. A segment of small intestine was removed from decapitated CF-1 mice ( Carnsworth Farms) and suspended in vitro in a beaker containing sterile phosphate-buffered saline. Bacterial transmigration was evaluated in this model over a three-day period at select temperatures (4, 25, and 37 degrees C) by microbiological cultures and scanning electron microscopy (SEM). Evidence of bacterial transmigration by SEM occurred within 2 to 3 h at 37 degrees C, 5 to 6 h at 25 degrees C, and 72 h at 4 degrees C. Analysis of the microbiological data indicated a differential flux of select bacterial and mycotic organisms. Staphylococcal species were the first organisms to be cultured from the suspending saline. These organisms are known to elaborate powerful protease enzymes that may play an important role in the degeneration of gut tissues. Coliform-type organisms and candida species were found at later times after death. The last major groups of bacteria to be identified were a variety of anaerobic species. This model may be adaptable to certain situations in human forensic pathology.

Animals↗
PubMed1981

A simplified in vitro assay of delayed hypersensitivity in diagnosis of dermatomycoses.

A tissue culture technique for detection of cellular hypersensitivity in an animal model of dermatomycoses is presented. It is based on specific inhibition of migration of leukocytes sensitized to dermatophytic antigens. The application and specificity of this new immunological technique were studied in guinea pigs infected with Trichophyton rubrum, Microsporum vanbreuseghemii, and Epidermophyton floccosum. In all the infected animals, sensitivity to trichophytin was demonstrated to be independent of the clinical disease phase. The in vivo skin-test reactions were common to those of the group of dermatophytes and did not distinguish between the different species. A statistical difference was observed in the leukocyte migration indices of sensitized cells to the homologous and the heterologous antigens of these pathogens (p less than 0.05, Student's test). It is concluded that the leukocyte migration inhibition assay provides a specific expression of cellular hypersensitivity and may be considered suitable for investigation of cellular immunity in vitro in clinical diagnosis or research. This is a simple, rapid, and inexpensive technique that requires small volumes of peripheral blood.

Animals↗
PubMed1980

Potential health hazards from microbial aerosols in densely populated urban regions.

Aerosolized bacteria were recovered up to 930 m downwind of three sewage treatment plants in Jefferson County, Ky. This distance includes homes in the proximity of several hundred such plants in that county. Bacterial counts were elevated on foliage near activated sludge tanks; although these counts decreased rapidly, at 48 h after exposure they were significantly higher than the counts on unexposed leaves. The 50% lethal dose of aerosolized Klebsiella pneumoniae was comparable to the 50% lethal dose of a virulent clinical isolate, and enteric bacteria were recovered from the respiratory organs of mice after forced inhalation adjacent to an aerated sludge tank. The coliform density in the effluents of the plants tested was inversely related to the airborne bacterial load at those plants. This relationship was attributed to the correlation between effluent quality and extent of aeration of activated sludge. Wind direction and distance influenced the airborne counts, but the extreme variation in counts indicates that it is not possible to predict emission rates accurately in an open ecosystem. Airborne enteric bacteria also were isolated near a decorative fountain used by humans for wading. The discovery of these sources of aerosolized microorganisms from polluted waters in densely populated areas suggests that a potential health hazard may be created by the increased probability of inhaling and ingesting microorganisms of fecal origin.

Aerosols↗
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↗
PubMed1968

Bordetella pertussis-induced alteration of the normal hyperglycemic response of mice to 3',5'-adenosine phosphate.

Blockade of the adrenergic receptors or the injection of Bordetella pertussis vaccine prevented the normal hyperglycemic response of CFW mice to exogenous cyclic 3',5'-adenosine phosphate (3',5'-AMP). The cyclic nucleotide was also ineffective in offsetting the histamine hypersensitivity of the beta-adrenergically blocked and the pertussis-sensitized groups. These observations suggest that the autonomic malfunction occurs at a point(s) subsequent to release of 3',5'-AMP. Neither the hyperglycemic effect of epinephrine or 3',5'-AMP, or both, nor the histamine sensitivity of pertussis-pretreated animals was influenced by the subcutaneous administration of theophylline.

Adenine Nucleotides↗