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Biomedical subjects

G Bjotvedt

Publications and source records attributed to G Bjotvedt.

18 recordsLinked to original sources
PubMed1993

Tumorigenic, invasive, karyotypic, and immunocytochemical characteristics of clonal cell lines derived from a spontaneous canine anaplastic astrocytoma.

Tumor cells from a spontaneously arising canine astrocytoma were isolated and cloned. Three clonally derived cell lines (DL3580 clone 1, DL3580 clone 2, and DL3580 clone 3) were developed and found to express glial fibrillary acidic protein (GFAP) as well as epidermal growth factor receptor (EGFR/c-erbB1). The cell lines were tumorigenic as subcutaneous xenografts or as intracranial implants in athymic mice, or both. Both the monolayer astrocytoma cells and the xenograft tumor cells from clone 2 were aneuploid, with a modal number of 84 chromosomes per metaphase; clones 1 and 3 were also aneuploid with modal numbers of 82 and 75/79, respectively. The histology of both the initial spontaneously occurring tumor in the dog and the intracranial astrocytoma in athymic mice demonstrated features of diffuse infiltration into normal brain. These newly developed canine glioma cell lines are karyotypically stable for 1 yr in culture and carry the same marker chromosomes as the parental lines. These glioma cell lines may serve as models for investigating mechanisms of glioma invasion into brain. Additionally, clonal cell lines with divergent properties isolated from the same tumor may assist in studies of the molecular basis of astrocytoma progression and heterogeneity.

Animals↗
PubMed1992

Environmental profile and critical temperature effects on milk production of Holstein cows in desert climate.

The environmental profile of central Arizona is quantitatively described using meteorological data between 1971 and 1986. Utilizing ambient temperature criteria of hours per day less than 21 degrees C, between 21 and 27 degrees C, and more than 27 degrees C, the environmental profile of central Arizona consists of varying levels of thermoneutral and heat stress periods. Milk production data from two commercial dairy farms from March 1990 to February 1991 were used to evaluate the seasonal effects identified in the environmental profile. Overall, milk production is lower during heat stress compared to thermoneutral periods. During heat stress, the cool period of hours per day with temperature less than 21 degrees C provides a margin of safety to reduce the effects of heat stress on decreased milk production. Using minimum, mean and maximum ambient temperatures, the upper critical temperatures for milk production are 21, 27 and 32 degrees C, respectively. Using the temperature-humidity index as the thermal environment indicator, the critical values for minimum, mean and maximum THI are 64, 72 and 76, respectively.

Animals↗
PubMed1988

Hemodynamic basis of renal arteriosclerosis in young greyhounds.

Renal arteriosclerosis occurs with unusually high frequency in young race-trained greyhounds. Light and electron microscopic studies were used to examine the arterial walls of renal vessels in six greyhounds. Lesions characteristic of mechanical forces, namely pressure and shear stresses, were found consistently on the endothelial surfaces of damaged vessels. Such damage was found in both the main renal vessel and its branches. Although the patterns of endothelial damage showed quantitative differences among individuals, the qualitative features were remarkably similar in the group. Quantitatively, fibrous plaques were greatest in narrow and curved portions of renal vessels. The plaques were found on the outer luminal surface of the bend and the bifurcation segments, but were absent on the flow dividers. Hemodynamic forces appear to play an important role in the pathogenesis of renal fibrous plaques. Renal arteriosclerosis in greyhounds provides an excellent model for the study of pressure pulse velocity and shear stress damage under various physiological conditions.

Animals↗
PubMed1986

Experimentally induced Histoplasma capsulatum infection in coyotes and a dog.

Captive coyotes (Canis latrans) were inoculated intragastrically (1 coyote), and intratracheally (6 coyotes) with Histoplasma capsulatum to simulate natural routes of exposure. In addition, the infectious organism was inoculated IV into another coyote and into a dog (C familiaris) to simulate hematogenous dissemination of H capsulatum. Isolation of the pathogen from various tissue specimens, using direct plating and mouse inoculation methods, provided mycologic evidence of infection. The presence of anti-Histoplasma serum antibodies also was monitored. Of the 6 coyotes challenged intratracheally, one developed a benign pulmonary form of histoplasmosis. This coyote developed a transient cough, and intracellular yeasts typical of H capsulatum were observed microscopically in pulmonary tissue specimens. The pathogen was isolated from specimens of pulmonary tissue and associated lymph nodes. The coyote that was fed Histoplasma-infected mice (intragastric challenge) did not develop clinical disease. The coyote and the dog inoculated IV developed a multifocal, nonsuppurative infection, without clinical evidence of histoplasmosis. Pathologic findings in the coyote and dog were similar; both animals had splenitis, lymphadenitis, and petechiation of the lungs. The liver and spleen were considered the primary extrapulmonary target organs on the basis of mycologic and histologic findings.

Animals↗
PubMed1966

Unilateral renal dysgenesis in a mongrel dog.

A case of unilateral (left) renal dysgenesis was discovered in a mongrel female dog. Retrograde pyelograms revealed both ureters to be normal in calibre and patent throughout their course. Microscopically, the kidney rudiment consisted of a cystic cavity lined by transitional epithelium and surrounded by fibrous tissue which contained both atrophic tubules and heterotopic bone. Gross inspection showed no obvious anomalies of the adrenals, urinary bladder, or genital organs.

Animals↗
PubMed1965

Phage patterns of coagulase-positive Staphylococci isolated from dogs.

One hundred and thirty-seven coagulase-positive strains of Staphylococcus aureus, isolated from dogs, were tested against three synthetic penicillins (cloxacillin, dicloxacillin, and ampicillin) and also phage typed using bacteriophages which are employed in typing staphylococci isolated from man.

Animals↗
PubMedDate not supplied

In vivo results of hydrogel composite pericardial substitutes.

In this study, two improved pericardial patches were developed and evaluated for their efficacy as pericardial substitutes. The patches are composites consisting of a hydrogel (PHEMA) that coats an underlying mesh (either ETFE or PET). Studies were conducted using subcutaneous implants in rats and pericardial patch implants in greyhound dogs. Adhesions between the substitute and pericardium and the epicardium were minimal. The ETFE composite patch caused an unacceptable epicardial reaction. The PET patch results were encouraging; the epicardium was largely unaffected by the patch.

Animals↗