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Biomedical subjects

B Mitchell

Publications and source records attributed to B Mitchell.

At least 37 records · Page 2Linked to original sources
PubMed1982

Pneumonia in sheep associated with dipping in carbolic dips.

Fourteen outbreaks of pneumonia in sheep following dipping in carbolic dips were investigated at seven laboratories. Deaths commonly occurred between one and three days after dipping and fat young sheep of the Suffolk and Border Leicester breeds were most usually involved in outbreaks. The pneumonia was characterised by hyperaemic, oedematous and cyanotic lungs, and the main histological features were hyperaemia, fluid and cellular exudation into alveolar spaces, and widespread epithelialisation of alveolar walls. The microscopic changes differed from pneumonic pasteurellosis and no significant organisms were recovered from any of the lungs. One of 27 Dorset Horn lambs dipped in a batch of dip which had been incriminated in some episodes developed an epithelialising interstitial pneumonia, while two out of three Suffolk lambs dipped in twice the recommended strength of the same batch of dip became ill with severe pneumonia, apparently following skin absorption.

Animals↗
PubMed1982

Local modulation of progesterone production in human fetal membranes.

We have studied the ability of human fetal membranes (amnion, chorion, and decidua) to produce progesterone. Membranes were obtained from women at 38-41 weeks pregnancy following spontaneous onset of labor. The tissues were dispersed into single cell preparations using 0.05% collagenase in a Krebs-Ringer buffer system. Progesterone was measured by specific RIA. All 3 tissues produced progesterone in a significant dose-response relationship with added pregnenolone but chorion was significantly more active than the other membranes. Equimolar concentrations of dehydroepiandrosterone, estrone or estradiol cause significant inhibition (to 50%) of this activity but dehydroepiandrosterone sulfate and estriol did not. We conclude that human fetal membranes at term can produce progesterone and this production may be modulated by other steroids of fetal or maternal origin. Local regulation of progesterone production, without significant changes in circulating levels of progesterone, may have an important influence on local prostaglandin generation and hence on myometrial contractility.

Dehydroepiandrosterone↗
PubMed1982

Use of nonblood priming for open-heart surgery in dogs.

Three electrolyte solutions were used as priming perfusates for 1 hour of cardiopulmonary bypass in 9 dogs. Arterial blood pressure was maintained at a satisfactory level during perfusion and returned to the original ranges shortly after bypass. Measurement of various blood constituents indicated that they were constantly maintained in the normal range during the procedure. The PVC decreased sharply until the 3rd postperfusion day, then returned to the base-line values. Similar patterns were obtained for each solution, with no additional infusion being administered after bypass. All dogs recovered without complications and evidence of cerebral abnormalities was not seen. The dogs were euthanatized and necropsied 14 days after surgery and all major organs appeared normal on gross examination.

Animals↗
PubMed1980

Mesangiocapillary glomerulonephritis in lambs: the ultrastructure and immunopathology of diffuse glomerulonephritis in newly born Finnish Landrace lambs.

Renal biopsies were obtained by laparotomy from eight newborn C3 deficient Finnish Landrace lambs, and examined by light, electron and immunofluorescence microscopy. The capillaries of all glomeruli contained numerous neutrophils and peripheral capillary walls were thickened and refractile at high magnifications. Almost continuous subendothelial electron-dense deposits were seen in peripheral capillary walls. Large amounts of C'3, and small amounts of IgM and IgA were also seen in these sits. No IgG was seen in these glomeruli. Four lambs died within 96 hr of birth. The remaining four lambs all had severe clinical mesangiocapillary glomerulonephritis (MCGN) by 21 to 42 days after birth. Amounts of C'3, IgM and IgA in glomeruli had increased by comparison with amounts at birth, and IgG was present in the deposits. It was concluded that the processes ultimately expressed as MCGN in these lambs were initiated before birth.

Animals↗
PubMed1979

Calcium, magnesium, and growth control in the WI-38 human fibroblast cell.

WI-38 and SV40WI-38 cells have been synchronized using centrifugal elutriation. This technique allows for the rapid harvesting of early G1 phase cells from exponentially growing populations of both the normal and transformed cell. Using these cells, as well as WI-38 cells synchronized by serum deprivation, we have examined the effects of extracellular Ca and Mg levels on the progression of cells through G1 phase. A differential sensitivity to both Ca and Mg deprivation is observed between normal and transformed cells. The WI-38 cell requires higher levels of both ions for traversal of G1 phase and for continued proliferation as compared to the transformed cell. The temporal nature of the Ca and Mg requirements for the WI-38 cell has been examined during G1 phase. Ca is strictly required during early and late G1 phase, but not necessarily throughout mid-G1. An early as well as a late G1 Ca requirement is also found in serum-stimulated WI-38 cells. In contrast, the Mg requirement of WI-38 cells does not appear to be temporally well-defined. Mg appears to be a permissive factor, required throughout G1 phase rather than at certain prescribed intervals. On the basis of these data, it seems unlikely that these two cations exert their effects on cell growth entirely through a common competitive mechanism. Ca would appear to be involved in early serum or growth factor-mediated G1 events and later pre-S-phase events, as suggested in previous studies on other cell lines.

Calcium↗
PubMed1979

Small intestinal morphology and epithelial cell kinetics in lamb rotavirus infections.

Morphologic changes in the small intestine of rotavirus-infected gnotobiotic lambs were investigated by measurement of villi and crypts in histologic sections of jejunum, midgut, and posterior ileum. In midgut, villus atrophy developed within 12 hr of infection and was apparent until 72 hr after infection. Crypt hypertrophy was evident from 42 hr after infection until the end of the observation period (6 days after infection). Changes in posterior ileum were similar in extent, but jejunal changes were much less marked. The relatively mild effect in the jejunum is in accord with reports from other species, and provides a basis for questioning the assumption that human rotavirus affects mainly the foregut. Studies of epithelial cell kinetics were made on midgut using a microdissection and metaphase accumulation technique on sequential samples from anesthetized lambs. An increase in the cell production rate per crypt per hour from the overall control level of 5.8 was detected by 48 hr after infection. The maximum level of 21.2 was reached 8 days after infection, and this had returned to near normal by 15 days after infection. This large and sustained increase in crypt cell production probably underlies other previously described functional abnormalities.

Animals↗
PubMed1978

Surgical techniques for the serial sampling of cerebrospinal fluid and for electrocorticography in cattle.

During the investigation of a familial neurological disease of cattle with some similarities to human epilepsy serial sampling of lateral ventricular and cisternal cerebrospinal fluid and of electrocortical activity was undertaken. In this paper the surgical approach, the technical problems encountered and some solutions are discussed. Further possibilities for the development and application of the technique are indicated.

Animals↗
PubMed1977

Uridine diphosphate galactose 4'-epimerase deficiency. IV. Report of eight cases in three families.

Eight persons who had no activity of uridine diphosphate galactose 4'-epimerase in their circulating blood cells are known today. They were healthy members of three different families. Propositi were newborns discovered in a mass screening test for blood galactose which registered high levels of erythrocyte galactose-1-phosphate. Epimerase deficiency was restricted to circulating blood cells, but in liver biopsy specimens, in cultured skin fibroblasts and in activated lymphocytes epimerase was found to be normally active. Heterozygotes had intermediate red cell epimerase activity. There were no symptoms of galactose intolerance and no pathology related to the enzyme defect. All 8 epimerase deficient persons had a ccdee Rhesus genotype. Attempts at demonstrating genetic linkage between the epimerase and Rhesus loci were unsuccessful because of the difficulty encountered in ascertaining epimerase heterozygosity. Individuals with hereditary UDP-galactose 4'-epimerase deficiency appear to produce an unstable mutant enzyme requiring higher NAD concentration for maximum activity.

Aged↗