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Biomedical subjects

D G Anderson

Publications and source records attributed to D G Anderson.

At least 19 recordsLinked to original sources
PubMed1990

Changes in renal morphology and renin secretion in the golden-mantled ground squirrel (Spermophilus lateralis) during activity and hibernation.

Chronological changes in renal glomerular morphology and plasma renin activity were investigated during active and hibernating periods in the golden-mantled ground squirrel Spermophilus lateralis. The objective of this study was to determine whether the glomerular endothelium, visceral epithelium (podocytes), basement membrane, mesangial cells, proximal convoluted tubule cells and plasma renin activity exhibit measurable sequential differences between as well as within active and hibernating states at various time points. Limitations in the size of the experimental population prevented an evaluation of changes in these parameters during other important periods such as periodic arousal between hibernation bouts. In this study, glomerular endothelial pore number and epithelial filtration slit number significantly decreased by early hibernation when compared to those during summer activity, and then they increased back toward summer levels by late hibernation. In contrast, podocytic pedicel width along the glomerular basement membrane increased from summer activity to early hibernation, before significantly decreasing again by late hibernation. Mesangial cell and proximal convoluted tubule cell activity appeared increased during hibernation as compared to summer activity, whereas the width of the glomerular basement membrane showed no significant alterations throughout. Plasma renin activity significantly increased during early hibernation and mid-hibernation when compared to summer levels but had decreased by late hibernation toward summer values. The glomerular and plasma renin activity changes observed in this study clearly illustrate the drastic structural and functional adjustments which hibernating species make during torpor and also correlate well with the reported decrease in renal perfusion pressure and urine formation during hibernation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Physiological de novo thyroid hormone formation in primary culture of porcine thyroid follicles: adenosine 3',5'-monophosphate alone is sufficient for thyroid hormone formation.

We describe a method of culturing intact porcine thyroid follicles for physiological de novo thyroid hormone formation; the roles of cAMP and protein kinase-C in thyroid hormone formation were also studied. Thyroid follicles were obtained by digesting minced porcine thyroid tissue with 0.04% collagenase and cultured in Coon's Modified Ham's F-12 medium supplemented with 0.5% calf serum, 0.5 mU/ml TSH, other standard hormones, and 3 antibiotics (6H medium). On the fourth day of culture, 6000-8000 follicles/well were plated in 12-well culture dishes. On the sixth day, thyroid hormone formation was carried out by incubating thyroid follicles with 0.5 microM KI in the presence of 6H medium for 2 days in a 5% CO2-95% air incubator at 37 C. To examine the effects of cAMP and protein kinase-C on de novo thyroid hormone formation, follicles were incubated with KI in the presence of 1-2.5 mM (Bu)2cAMP, 10 microM forskolin, 2 microM prostaglandin E2 (PGE2), or 0.5-1 microM 12-O-tetradecanoylphorbol-13-acetate in TSH-free medium for 2 days. The amount of newly formed thyroid hormone was measured by RIA of T3 content in the Pronase digest of thyroid follicular cells. Thyroid follicles cultured in 6H medium had normal polarity of the membrane, determined by electron microscope, and thyroid cAMP was responsive to the alteration of TSH. In this culture system cAMP alone was sufficient to form thyroid hormone. 12-O-Tetradecanoylphorbol-13-acetate, a protein kinase-C stimulator, disrupted thyroid follicles and inhibited cAMP-mediated thyroid hormone formation. The integrity of follicular structure was also required for thyroid hormone formation in this culture system. This study introduces perhaps the most physiological culture system for de novo thyroid hormone formation. Our data provide direct evidence that thyroid hormone formation is linked to cAMP and that the protein kinase-C system acts as an inhibitor of thyroid hormone formation.

Animals↗
PubMed1988

Electron microscope study of the association between hypothalamic blood vessels and oxytocin-like immunoreactive neurons.

An association between oxytocin-like immunoreactive neurons and hypothalamic blood vessels has been observed with the light microscope. Recently, it has been demonstrated that oxytocin stimulates vascular smooth muscle contraction in vitro. A hypothesis has thus been proposed that oxytocin may play a role in modulating blood flow in certain brain regions. In a study on the golden-mantled ground squirrel (Spermophilus lateralis) we noted the association at the light microscope level between oxytocin-like immunoreactive neurons and blood vessels in preoptic and paraventricular nuclei of the hypothalamus. To determine if these neurons were associated with hypothalamic capillaries, transverse 30 micron immunostained hypothalamic sections were prepared for thin sectioning and observation by transmission electron microscopy. Oxytocin-like immunoreactive neurons were observed to lie within 77 nm of the edge of the lumen of capillary blood vessels. One neuronal cell body was observed approximately 380 nm from the edge of a capillary lumen and what appears to be an output region of a neuron was observed to terminate on the basement membrane of a capillary blood vessel.

Animals↗
PubMed1988

Escherichia coli F41 adhesin: genetic organization, nucleotide sequence, and homology with the K88 determinant.

The genetic organization of the polypeptides required for the biosynthesis of the F41 adhesin of enterotoxigenic Escherichia coli strains was investigated. Maxicell analysis demonstrated that a recombinant plasmid which mediated mannose-resistant hemagglutination and F41 antigen production encoded four polypeptides of 29, 30, 32, and 86 kilodaltons. The 29-kilodalton protein was identified as the F41 antigen, and the nucleotide sequence of the gene was determined. Extensive homology was observed between the region encoding the putative signal sequences of the F41 and K88 antigens and in the region immediately upstream of the antigen genes. The nucleotide sequence homology between F41 and K88 determinants was further investigated by Southern blot hybridization. A K88 probe hybridized at high stringency to all fragments shown to be essential for F41 production except for fragments internal to the F41 antigen gene.

Adhesins, Escherichia coli↗
PubMed1986

Validation of an in vivo developmental toxicity screen in the mouse.

A test system for identifying toxicity, including potential teratogenicity has been developed that is based on growth and viability of embryonic, fetal, and postnatal mice (J Toxicol Environ Health 10:541-550, 1982). To test the utility of this assay, a series of 55 compounds was administered to timed-pregnant ICR/SIM mice during organogenesis. The test compounds included known teratogens, known nonteratogens, and equivocal teratogens. They represented a wide variety of classes including pesticides, organic solvents, metals, steroids, nutrients, food additives, antimetabolites, alkylating agents, and pharmaceutical agents. A single dose level, at or near the level producing overt maternal toxicity in preliminary range-finding studies, was administered by gavage on gestation days 8 through 12. Females were allowed to deliver; litter size and weight on the day of birth and 2 days postpartum were recorded, and stillborns were examined. Dams that had not given birth by gestation days 21 or 22 were killed and their uteri were examined. The results confirmed a strong correlation between reported teratogenic activity and embryo/fetal viability, and/or postnatal growth and viability. The results indicate that this test system is an effective, cost-efficient means of prioritizing compounds for more detailed teratogenicity testing.

Animals↗
PubMed1986

Blood glucose monitoring by children at home: a comparison of methods.

The accuracy of measurements of blood glucose performed at home by the index children and/or parents was compared using the Boehringer Mannheim reagent strips, Ames Visidex-2 strips, an Ames Glucometer and a Boehringer Mannheim Reflolux reflectance meter. Capillary plasma samples, collected simultaneously, were later analysed by a Beckman glucose oxidase analyser. The coefficient of correlation between the self-monitored results (SMR) and the laboratory-analysed results (LAR) ranged from 0.59 to 0.92, the composite being 0.74. The mean difference between the SMR and the LAR was 1.0 mmol/l. The occurrence of potential errors of management due to incorrect SMR results was determined. On four occasions, the SMR was greater than 6 mmol/l when the LAR was less than 3 mmol/l, and on 36 occasions a discrepancy greater than 50% occurred between the two values, without resulting hypoglycaemia.

Adolescent↗
PubMed1985

Comparison of the radiosensitivity of interleukin-2 production between species, between tissues, and between young and old individuals.

The radiosensitivity of interleukin-2 (IL-2) production was assessed of (a) peripheral blood mononuclear cells (PBMC) of young humans, dogs, and mice (C57BL/6); (b) PBMC and splenic cells of young mice; and (c) PBMC of young and old humans and the splenic cells of young and old mice. The results indicate that (a) large differences in radiosensitivity exist between the PBMC of humans, dogs, and mice (e.g., the radiation doses which resulted in 37% remaining IL-2 activity (D37) of human, dog, and mouse PBMC were 3771, greater than 10,000, and 1398 rads, respectively); (b) only a small difference exists between the PBMC and splenic cells of mice; and (c) no difference exists between the PBMC of young and old humans and between splenic cells of young and old mice. Topological abnormalities, as judged by scanning electron microscopic analysis, could not be detected in dog PBMC after their exposure to 1800 rads, but could be detected in mouse PBMC after their exposure to 400 rads.

Adult↗
PubMed1985

Gorgosterol biosynthesis: localization of squalene formation in the zooxanthellar component of various gorgonians.

Four species of gorgonians: three related pseudoplexaurids Pseudoplexaura porosa, P. flagellosa and P. wagenaari; and the unrelated Pseudopterogorgia americana, are sources of zooxanthellae capable, in purified broken cell preparations, of converting [14C]labeled farnesyl pyrophosphate into squalene. More extensive studies with P. porosa and P. americana zooxanthellae preparations characterize the conversion as enzymatic and demonstrate farnesyl pyrophosphate and reduced pyridine nucleotide as substrates. NADPH and NADH are essentially equivalent. Anaerobic conditions are not required. Despite numerous attempts zooxanthellae formation of sterols, including gorgosterol, from radioactive substrates was unsuccessful. By enzyme studies, we can show only the conversion of mevalonate into squalene as a zooxanthellae capability.

Animals↗
PubMed1979

Endometrial carcinoma: causes of death and sites of treatment failure.

A retrospective analysis of causes of death in 398 patients with endometrial carcinoma and sites of treatment failure in 105 cases, all seen at the University of Michigan Medical Center between 1930 and 1971, is the subject of this report. Of 398 patients (337 with Stage I, 61 with Stage II disease), 183 (46%) died with endometrial carcinoma, and 122 (31%) died free of cancer. The cause of death in 35 cases (9%) was a known or unknown maligancy, and remained undetermined in 58 patients (14%). The exact site of treatment failure was identified in 105 cases. Forty-one (40%) failures were considered local, 32 (30%) geographic, and 32 (30%) both local and distant. The uterus and lungs were the most common sites of local failure and distant metastasis, respectively. Of patients who died free of cancer, 88% survived 5 or more years, and 32% survived 20 years or longer. It is concluded that 1) Hematogenous dissemination of endometrial carcinoma may occur early and with appreciable frequency. Thorough pretreatment investigative workup, preferably including chest laminograms and liver scans and consideration of adjuvant systemic therapy in advanced cases (i.e. those with positive nodes) is recommended. 2) The uterus, a common site of local failure, must be removed whenever feasible. 3) A realistically aggressive approach to the treatment of patients with endometrial cancer is justifiable despite their older age and coexistent medical problems.

Adolescent↗
PubMed1979

Benign gestational trophoblastic disease metastatic to pleura: unusual cause of hemothorax.

A unique case of hemothorax caused by proven pleural involvement with benign gestational trophoblastic disease and anticoagulation is presented. The pulmonary manifestations of gestational trophoblastic disease are reviewed. It is stressed that these may be associated with histologically benign as well as frankly malignant disease, and that the clinician must be alert for them in managing all patients with known or suspected gestational trophoblastic disease.

Adolescent↗
PubMed1977

Plasmids, loss of lactose metabolism, and appearance of partial and full lactose-fermenting revertants in Streptococcus cremoris B1.

The unstable ability to metabolize lactose (lac) via the phosphoenolpyruvate-phosphotransferase system (PTS) was examined in Streptococcus cremoris B1. The presence of functional lactose-specific PTS enzymes was correlated with the presence of a distinct plasmid species. Characterization of deoxyribonucleic acid extracted from lactose-positive (Lac+) S. cremoris B1 revealed two plasmids having molecular weights of 9 X 10(6) and 36 X 10(6). An acriflavine (BC1)-induced, lactose-negative (Lac-) mutant possessed no plasmids and was devoid of all three lac-specific PTS enzymes. A Lac- mutant (DA2) isolated by growing at elevated temperatures only possessed the 9 X 10(6)-dalton plasmid and also lacked the lac PTS enzymes. A spontaneous Lac- mutant possessed both the 9 X 10(6)-and 36 X 10(6)-dalton plasmids. This mutant displayed FIII-lac and phospho-beta-D-galactosidase (P-beta-gal) activity but was deficient in EII-lac activity. The spontaneous Lac- strain reverted to both full and partial lactose-fermenting phenotypes having FIII-lac, EII-lac, and P-beta-gal activities. BC1 and DA2 Lac- mutants reverted only to the partial lactose-fermenting phenotype having P-beta-gal activity; EII-lac and FIII-lac activities were absent. The results indicate that the genetic determinants for EII-lac, FIII-lac, and P-beta-gal are located on the 36 X 10(6)-dalton plasmid in S. cremoris B1. Evidence for a second chromosomally associated P-beta-gal gene operating in the partial lactose-fermenting revertants is also presented.

DNA, Bacterial↗
PubMed1976

The cytologic diagnosis of endometrial adenocarcinoma.

An outpatient diagnositc technique comparable to the Papanicolaou smear for carcinoma of the cervix is needed to permit early recognition of adenocarcinoma of the endometrium. Five different techniques of sampling the endometrial cavity were carried out on 1, 742 patients at the University of Michigan Medical Center. A total of 2,553 specimens were correlated with operating room curettings to assess the accuracy of each sampling technique. The methods of saline irrigation with an antrum cannula, endometrial brush sampling, high-vacuum aspiration, and the Gravlee jet washer proved not to be accurate enough to be used as a routine screeening test. There was excellent correlation (96 per cent) between endometrial biopsies and curettings. In our experience, endometrial biopsy with a suction or basket curette was the diagnostic technique short of curettage which permitted accurate diagnosis.

Adenocarcinoma↗
PubMed1975

The effect of immunizing female rats with modified rat pituitary extract.

Immune reactions to a number of hormones have been induced, but information is lacking on the feasibility of inducing immune reactions to homologous gonadotropins. Female rats immunized with diazotized and tyrosylated rat pituitary extract containing gonadotropic activity and emulsified in complete Freund's adjuvant expressed various reproductive disturbances such as increased cycle length (7.0 days), increased number of sterile matings, reduced implantation in animals becoming pregnant, and reduced ability to carry fetuses to term. These effects were not exhibited by rats immunized similarly with diazotized or tyrosylated rat pituitary extract containing no detectable gonadotropic activity. Rats not becoming pregnant had a significantly higher antibody level to rat luteinizing hormone than did rats becoming pregnant. No significant elevation of rat follicle-stimulating hormone antibodies was noted. It is concluded that auto-immune reactions to gonadotropins can be induced and that very low levels of antibodies have a significant effect on reproduction.

Animals↗
PubMed1975

Implanted amniotic membrane as an autograft and as an allograft.

Detailed studies on autograft and allograft amniotic membranes implanted in the subcutaneous tissues to form tunnels are described. Autograft amniotic membranes appear to become permanent structures whereas allografts of this material, though accepted by the host for a longer time than most allografts, were eventually rejected. Serial histological studies were performed.

Amnion↗
PubMed1975

Amnion autografts, permanent structure.

Autografts of amniotic membrane were used to form tubes or conduits in lambs. These conduits survived for periods up to 9 months. The possibility of a clinical application has been explored.

Amnion↗
PubMed1975

Wound healing and the amniotic membrane.

The successful clinical application of the amniotic membrane as a surgical dressing is discussed as to the mode of healing. The amniotic membrane does not appear to be a permanent structure when used as an allograft.

Amnion↗