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Biomedical subjects

J P Davidson

Publications and source records attributed to J P Davidson.

28 records · Page 2Linked to original sources
PubMed1980

Metastatic, papillary cystadenocarcinoma of the mammary gland in a black-footed ferret.

A simple, papillary cystic adenocarcinoma of the mammary gland with metastases to the internal iliac and mesenteric lymph nodes, liver, and spleen was observed in a 12 to 13 year old female black-footed ferret (Mustela nigripes). Histologically, the tumor was aggressive, and lymphatic invasion was found. Attempts at virus isolation were negative. Other findings were bilateral infarcts in the kidneys, apparently resulting in acute renal shutdown and death, multiple thrombi in the right atrium, aortic arteriosclerosis, and focal interstitial pneumonia.

Animals↗
PubMed1979

Heart failure associated with unusual hepatic inclusions in a Deckert's rat snake.

A juvenile Deckert's rat snake, Elaphe obsoleta deckerti, was presented with a circumferential enlargement of the body in the region of the heart. The heart was enlarged approximately twice normal size. Focal mineralized lesions were present in the tunica media of the right aorta and the right atrioventricular valve. The normal sinusoid architecture of the liver was disrupted with deeply eosinophilic to lightly basophilic granules of variable size in the cytoplasm and light eosinophilic intranuclear inclusions. Similar appearing intracytoplasmic granules were seen in the glomeruli and kidney tubules.

Animals↗
PubMed1979

Endometrial histology and post-partum mares treated with progesterone and synthetic GnRH (AY-24,031).

Foal heat was significantly delayed in 15 Thoroughbred and Quarter-horse mares by 200 mg progesterone in oil from Days 5--14 post partum. Nine of these mares subsequently received daily i.v. injections of 2 mg of a synthetic GnRH preparation (AY-24,031) from Day 2 of the progesterone-delayed oestrus but this treatment did not significantly shorten oestrus or hasten ovulation. Uterine biopsies taken on Day 15 post partum from all the mares showed a mixed endometrial morphology having both oestrous and dioestrous characteristics. There was an increased proliferation of endometrial glands in these animals at the time of ovulation compared to control mares having a normal foal heat.

Animals↗
PubMed1976

Fly's eye: a counting camera for thermal neutrons-some applications, problems, and prospects.

An area detector for thermal neutrons based on image intensification techniques has been described. Some capabilities and limitations of the detection system have been discussed. Among the former are high spatial resolution, high instantaneous counting rate, electronic zoom, time-gating, and integration. The detector is limited in that the maximum counting rate for a resolution element is 60 regularly spaced counts per second. Also, the nonuniformity of response over the detector puts a limit on the useful size and necessitates point-by-point calibration. In addition, a higher efficiency for neutron detection would be desirable. Some typical applications of the system are crystal inspection, neutron magnetic diffraction topography, and searches for temperature-induced changes in diffraction patterns. The future application of solid-state television sensors and microchannel-plate intensifiers to improve the system were briefly mentioned.

Computers↗
PubMed1975

Enteric colibacillosis: evaluation of strains of Escherichia coli utilizing the ligated loop technique in gnotobiotic swine.

The enteropathogenicity of 6 strains of Escherichia coli was evaluated via the ligated loop technique in 15 gnotobiotic swine 3 to 4 weeks old. Strain enteropathogenicity in gnotobiotic swine, as determined on the basis of visual loop distention and light microscopic evaluation of intestinal sections, compared favorably with that reported in conventional swine, except that jejunal loops of gnotobiotic swine may be somewhat less sensitive to certain strains. In addition, postoperative mortality rate among gnotobiotic pigs was greater than that reported in conventional pigs. Two types of aberrant loop reactions were observed during the experiment. The 1st, and the more commonly encountered type, was due to the leakage of enteropathogenic organisms or enterotoxin from one loop to another; this was considered to be a true false-positive reaction. The 2nd type of unexpected positive reaction occurred in 2 sacs inoculated with the nonenteropathogenic strain 115. This latter reaction may have represented either a reversion of the organism to its previous enteropathogenic state or a unique reaction of the gnotobiotic intestine to this strain. False-positive loops were not identified in any other sacs, whether inoculated or not. Results of these experiments support the hypothesis that false-positive loops originate from naturally occurring infection.

Animals↗
PubMedDate not supplied

"Platinum-pyrimidine blues" and related complexes: a new class of potent antitumor agents.

The diaquo species of cis-dichlorodiammineplatinum (II) reacts with pyrimidines and substituted pyrimidines to form very soluble, deep blue complexes. These are believed to consist of mainly monomeric species containing one pyrimidine moiety liganded to each platinum. The structures of the complexes are largely uncertain at this time. We describe the methods of synthesis and characterization of approximately 70 such complexes, with a suggested classification scheme, incluse complexes show superior activity against the ascites Sarcoma 180 tumor in Swiss mice when compared to cis-dichlorodiammineplatinum (II). Initial screening test results and dose schedule-dependency results indicate we can achieve 100% cures in this tumor-host system. Activity is also shown against the Rauscher leukemia, Ehrlich ascites, and ADJ/PC6A tumors. Microscopic histopathologic studies of resulting kidney lesions show that the "platinum-uracil blue" complex causes only minor focal damage to the proximal convoluted tubules at a therapeutic dose level, rather than the generalized degenerative changes so prominent and dose limiting noted with cis-dichlorodiammineplatinum (II).

Animals↗
PubMedDate not supplied

Epizootiology, pathology, and microbiology of an outbreak of urolithiasis in chickens.

An outbreak of urolithiasis that doubled the annual mortality rate of chickens in a large flock of table-egg-layers is described. Despite the presence of a large unilateral urolith and/or severe renal atrophy, the layers often maintained active egg production and apparent homeostasis until a small urolith blocked the ureteral flow from the contralateral kidney. This terminal episode appeared to produce acute obstructive renal failure, rapidly developing visceral gout (visceral urate deposition), uremia, and death. The atrophy observed appeared to be acquired and progressive. Histologic features in the kidneys were acute to chronic glomerulonephritis, interstitial nephritis, and pyelonephritis. Epizootiologic and microbiologic studies indicated that a combination of infectious and noninfectious mechanisms may have been involved. Causative roles for calcium-phosphate imbalance, infectious bronchitis (IB), Newcastle disease (ND), and adenovirus or reovirus infections could be neither excluded nor confirmed. Contributory factors may have been spray ND-IB and other vaccinations of 15-week-old ND-IB-susceptible pullets, water deprivation, shipping stress, Mycoplasma synoviae infection, immune complex disease, and mycotoxins.

Animals↗