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Biomedical subjects

S J Withrow

Publications and source records attributed to S J Withrow.

At least 91 records · Page 5Linked to original sources
PubMed1988

Efficacy and toxicity of tamoxifen citrate for prevention and termination of pregnancy in bitches.

Five groups of bitches were given tamoxifen citrate (1 mg/kg of body weight) orally twice daily for 10 days. Drug administration commenced during late proestrus, day 4 of estrus, day 2 of diestrus, day 15 of diestrus, or day 30 of diestrus (n = 4/group). Nineteen of the bitches accepted natural mating by 1 or more of 3 stud dogs of known fertility (1 bitch did not). Twenty days after cessation of drug administration, ovarian, uterine, and hepatic specimens were obtained from each bitch in 4 of the groups. Pregnancy proceeded to natural termination in bitches of the remaining group (diestrous day 30). Pregnancy was not detected in any bitch of the proestrus, estrous, or early diestrous groups. Of 4 bitches of each of the remaining groups (diestrous day 15 and diestrous day 30), 2 aborted fetuses and/or resorbed placental remnants; the other 2 bitches in each of these groups had normal-appearing fetuses (diestrous day-15 group) or clinically normal pups (diestrous day-30 group). Of the 20 bitches given tamoxifen citrate, 5 developed endometritis with or without pyometra, and 4 of these had ovarian cysts. Although tamoxifen citrate is effective for preventing or terminating pregnancy in the bitch, the regimen used in the study reported here was associated with high frequency of pathologic changes in the reproductive tract.

Abortion, Induced↗
PubMed1987

Radiotherapy of malignant nasal tumors in 67 dogs.

The nasal cavity of 67 dogs with malignant nasal neoplasia was treated with radiation. Preirradiation surgical cytoreduction of the tumor was done in 41 dogs. Fifty dogs were irradiated by use of 10 fractions over 22 days, and 17 dogs were given a similar total dose in 5 fractions over 35 days. The range of survival times (0.5 to 42 months), median survival time (8.5 months), and 1- and 2-year survival rates (38% and 30%, respectively) were better than those expected for other methods of treatment. Serious complications were few (4%). Survival times for dogs were determined on the basis of histologic tumor type and on the basis of megavoltage (cobalt or linear accelerator) vs softer deep radiation (cesium or orthovoltage) treatment, with or without cytoreductive surgery. Survival times of 10 dogs given softer radiation without surgery were shorter than those of 14 dogs that were given softer radiation and had cytoreductive surgery. Survival times of dogs that were given softer radiation and had surgery were similar to those of dogs that were given megavoltage radiation only. Cytoreductive surgery did not improve survival times for dogs that were given megavoltage radiation. Median survival time for 38 dogs with adenocarcinoma was 12 months, compared with 6 months for 14 dogs with squamous cell or undifferentiated carcinoma. Median survival time for 16 dogs with a variety of sarcomas was 11.2 months. Survival times of dogs with adenocarcinoma or sarcoma were significantly better (P less than 0.02 or 0.03) than for dogs with squamous cell or undifferentiated carcinoma. Necropsies were performed on 27 of 58 dogs that died or were euthanatized.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1987

Ophthalmic complications following megavoltage irradiation of the nasal and paranasal cavities in dogs.

Megavoltage x-radiation was used to treat orbital nasal, and paranasal cavity malignant neoplasia in 29 dogs. In each instance, the globe and adnexal tissues were within the treatment portals (entry and/or exit). Doses administered to tumors ranged from 3,680 to 5,000 cGy. Ocular reactions after irradiation were classified as mild in 5 of 29 cases (17.2%) and severe in 17 of 29 cases (58.6%). No ocular complications were noticed in 7 of 29 cases (24.1%). Complications frequently noticed included severe keratitis (41%), mild conjunctivitis (34%), severe conjunctivitis (28%), cataract (28%), and keratoconjunctivitis sicca (24%). Ocular complications that developed were not life threatening, but posed a threat to visual function and patient quality of life. Treatment for the complications included control of bacterial infection, reduction of tissue inflammation, and ocular surface protection when tear film deficiencies were noticed. Mild complications represented acute effects of irradiation, and typically resolved. Severe complications developed both acutely and as late irradiation effects. Those attributed to late irradiation effects were more vision threatening and altered the quality of life more than did the early effects.

Animals↗
PubMed1987

Intraoperative irradiation of the canine abdominal aorta and vena cava.

The canine abdominal aorta and vena cava were examined 6 months after single doses of intraoperatively delivered electrons (IORT), fractionated external beam X rays, or a combination. The predominant pathologic change in aortas given fractionated doses was a segmental thickening of the subendothelial region of the tunica intima which was due to fibroelastic proliferation. In severe cases, the intimal proliferation caused significant narrowing of the aortic lumen. The greatest proliferation and lumen narrowing resulted from 80 Gy given in 30 fractions, whereas 60 Gy produced little response. In contrast, IORT alone or combined with fractionated doses resulted in mild subendothelial intimal proliferation at all doses. In some aortas there was focal aortic wall thinning after IORT alone or combined with fractionated doses. This response may be explained by increased intimal cell death and lost or delayed proliferative capability caused by large single doses. These studies suggest that large single doses produce structural alterations in the walls of large blood vessels that are clinically undetectable at early post-irradiation times. If these changes progress in severity they could lead to late effects such as rupture, fissure, or aneurysm that are clinically more significant than the marked intimal proliferation and lumen narrowing changes seen after fractionated doses. The aortic cell responsible for intimal fibroelastic proliferation appears to be a pluripotential stem cell capable of producing fibrous, elastic, and possibly smooth muscle tissue. There were no significant alterations in any of the irradiated vena cavas.

Abdominal Neoplasms↗
PubMed1987

Effect of RA233 on metastasis in dogs with osteosarcomas.

The influence of RA233, an inhibitor of platelet function, on the occurrence of metastasis in 18 dogs with osteosarcomas was evaluated. At least 24 hours before surgical removal of the primary tumor, dogs were given RA233 orally (20 mg/kg of body weight divided into 3 equal doses). Original sites of the osteosarcoma included humerus, 6 dogs; radius, 5 dogs; tibia, 3 dogs; femur, 2 dogs; maxilla, 1 dog; and mandible, 1 dog. Survival time for 13 dogs euthanatized for progression of neoplastic disease ranged from 3 months to 10 months, with a mean survival time of 5.5 months. Medication was discontinued in 1 dog because of possible adverse reaction. One dog died of disease unrelated to the tumor, and one dog was euthanatized after the surgery. Two dogs were tumor free 9 and 17 months after surgery. Seemingly, the metastasis potential was not diminished in dogs given 20 mg of RA233/kg/day.

Animals↗
PubMed1986

Use of radiotherapy for the treatment of intranasal tumors in cats: six cases (1980-1985).

Six cats with intranasal neoplasia treated with radiotherapy were evaluated. The mean survival time from the initiation of radiotherapy was 19 months, with 2 cats still known to be alive. Two cats died for reasons unrelated to the primary tumor. One cat had no clinical evidence of nasal tumor 41 months after treatment, but was lost to further follow-up evaluation.

Adenocarcinoma↗
PubMed1986

Radiographic bone surveys in the evaluation of primary bone tumors in dogs.

Forty-two dogs with primary bone tumors underwent radiographic bone surveys. The use of radiographic bone surveys led to a higher yield in finding other nonclinically detectable neoplastic sites (7.1%) than did thoracic radiographs (4.7%). Multicentric bone tumors accounted for 9.5% of total cases. Bone infarcts were identified in 3 dogs (7.1%).

Animals↗
PubMed1986

Influence of WR 2721 on radiation response of canine soft tissue sarcomas.

Seventy-three dogs with soft tissue sarcomas were randomized to 2 dose response assays to receive irradiation alone or with the radioprotector WR-2721. Nausea and vomiting were the major side effects of WR-2721 administration although one death occurred because of cardiac and respiratory failure which may have been caused by the WR-2721. There was no change in blood counts or serum chemistry values. The TCD50/lyr was 52 Gy delivered in 10 fractions for both groups. However, there was an indication of tumor protection at lower doses because at all comparable dose levels the percentage tumor control was lower in dogs given WR-2721. There was no decrease in acute skin reactions of dogs treated with WR-2721 and little, if any, protection against fibrosis, soft tissue necrosis or bone necrosis. The lack of protection of normal tissues may have been caused by fractionation. The agent may be more useful combined with large single doses such as given in intraoperative radiotherapy.

Amifostine↗
PubMed1985

Hepatic neoplasia.

The clinicopathologic features of hepatic neoplasms such as hepatocellular adenomas, hepatocellular carcinomas, bile duct carcinomas, and hepatic carcinoids are presented. The authors also discuss the diagnostic and therapeutic approaches to hepatic neoplasia.

Adenoma, Bile Duct↗