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Biomedical subjects

G Lumb

Publications and source records attributed to G Lumb.

At least 19 recordsLinked to original sources
PubMed1992

Serum parathyroid hormone and calcitonin levels following ovariectomy in the adult rat.

The ovariectomized rat is a reasonably good and often utilized model of human post-menopausal osteoporosis (Devlin and Ferguson, 1989). Mature rats were either ovariectomized or underwent a sham operation, killed at intervals following operation and the serum concentration of parathyroid hormone and calcitonin at death related to the histomorphometry of the cancellous bone of the proximal ilium. The mean serum calcitonin concentration for all ovariectomized rats was 66.4 pg/ml (SD = 18) and for the control rats was 76.42 pg/ml (SD = 20). The serum calcitonin concentration in the ovariectomized rats was significantly negatively correlated with the extent of erosion cavities of the cancellous bone (r = -0.598, t = -2.36, p = 0.039). No significant correlation was observed for the control rats (r = -0.107, t = -0.357, p = 0.727). The mean extent of erosion cavities in the ovariectomized group was 6.81% (SD = 1.94) and in the control group was 6.47% (SD = 2.21), with no significant differences between the two groups (t = 0.41, p = 0.69). No significant correlations were observed in serum parathyroid hormone (PTH) concentration with the bone resorption parameters. From this study it was concluded that calcitonin may be of aetiological importance in bone loss in the ovariectomized rat.

Animals↗
PubMed1992

The problems of water pollution: an overview.

Most potentially toxic chemicals eventually find their way into waterways. The most common source of this pollution is from the air. More than 50 percent of the chemical pollution of the Great Lakes is believed to come from airborne pollutants, and the main sources of this pollution are smokestacks (energy plants, nuclear or conventional; trash-to-steam incinerators; industrial factories, chemical and wood pulp) and road traffic exhaust. Chemicals may reach waterways directly through partially filtered or untreated sewage and waterway traffic, both industrial and pleasure; or they may be deposited into the soil and reach rivers and estuaries through leakage (PCBs on cables, landfills, and regular or low-level nuclear waste) or locally from fields (fertilizers, herbicides, phosphates, and other chemicals.

Animals↗
PubMed1989

A modified Brown and Hopps stain for identification of gram-positive and gram-negative microorganisms in glycol methacrylate-embedded tissues.

Plastic embedding is a recently developed technique that has been shown to be superior to conventional paraffin embedding in the histopathologic identification of microorganisms in tissue specimens. This report describes a modification of the Brown and Hopps stain for the differentiation of gram-positive and gram-negative microorganisms in 3-micron-thick plastic sections. This technique is easily performed and has a rapid turnaround time. This staining method permits a more precise histopathologic diagnosis of infectious agents than is possible in paraffin-embedded tissues.

Acrylates↗
PubMed1988

Antigen localization in immunoperoxidase-stained plastic-embedded soft tissues.

Immunoperoxidase stains were performed on normal and neoplastic tissue from prostate, colon, thyroid, lung, nerve, uterus, and placenta embedded in both plastic (glycolmethacrylate [GMA]) and paraffin. Positive results in plastic section were obtained for carcinoembryonic antigen (CEA), keratin, epithelial membrane antigen (EMA), thyroglobulins, S-100, prostate-specific antigen, human chorionic gonadotrophin (HCG), and beta-HCG. More delicate staining with more precise localization of antigens is noted. Superior (paraformaldehyde) fixation and cold processing followed by GMA polymerization (4 degrees C) allow for optimum antigen survival. After fixation, tissue processing involves a series of 0.1 mol/L phosphate buffer rinses with sucrose and ammonium chloride in a conventional dip-and-dunk processor placed in a 4 degrees C cold room. Acetone dehydrations are used before GMA infiltration, cold polymerization, and sectioning. Before immunoperoxidase staining, the plastic section is digested in .25% bovine trypsin for ten minutes. The immunoperoxidase methods described can be useful when small biopsies are routinely embedded in plastic to obtain improved histologic (hematoxylin-eosin) sections. There may also be research applications in quantifying antigen expression in benign, dysplastic, and neoplastic tissues by examining the stains under high power.

Adenocarcinoma↗
PubMed1985

Regression of pathologic changes induced by the long-term administration of contraceptive steroids to rodents.

The induction of pathologic changes with hormone steroids has been studied in rodents, although comprehensive studies are lacking on the potential reversibility of these lesions. For these purposes, groups of rats were treated with quingestanol acetate and quinestrol, a progestogen-estrogen combination, for 50 weeks and observed for a subsequent 30-week period. Treatment resulted in a significant body weight gain suppression and reduction of food consumption which recovered after withdrawal. Other significant treatment-related effects were hair loss, ataxia due to pituitary enlargement, mammary chain masses with histologic adenocarcinoma, lens opacities, ovarian atrophy with follicular arrest, and uterine atrophic changes with suppurative inflammation throughout 50 weeks. Cessation of treatment did not effect hair loss or lens opacities, while mammary chain masses decreased in size and in incidence; mammary gland tumors showed regressive changes including the disappearance of adenocarcinoma, and the incidence of ataxia diminished together with reduced pituitary weights. Chromophobe cell hyperplasia with decreased eosinophils and acidophils and hemorrhage into the pituitary was observed up to 50 weeks and the tinctorial affinity of basophils and acidophils returned after withdrawal. Ovaries and uteri, which become atrophic and sustained chronic suppurative inflammation in the treatment phase, showed reduction of inflammatory reaction and disappearance of suppuration after withdrawal, and endometrial regeneration occurred with luteal cells seen in the ovaries. These results revealed the regressive characteristics of some of the mammary gland carcinomas as well as steroid-induced endocrine and pathologic lesions other than tegumentary and ocular changes in rats receiving high levels of steroids for prolonged periods of time.

Adenocarcinoma↗