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Biomedical subjects

A W Fetter

Publications and source records attributed to A W Fetter.

At least 19 recordsLinked to original sources
PubMed1992

Glycoprotein hormone alpha-subunit-producing pituitary adenomas in rats treated for one year with calcitonin.

Calcitonin, a calcium-lowering hormone, has been associated with an increased incidence of nonfunctioning pituitary tumors in rats. In this study, rats were treated with calcitonin (80 IU/kg/d) for 52 weeks. After treatment with calcitonin, immunohistochemistry and in situ hybridization analyses demonstrated that most pituitary tumors expressed the glycoprotein hormone alpha-subunit. Expression of the alpha-subunit was identified rarely in hyperplastic lesions of control animals. Serum levels of GH, PRL, ACTH, LH, and FSH were unchanged in calcitonin-treated rats relative to controls. However, TSH levels were increased 2.1 fold after chronic treatment with calcitonin in both male and female rats (P less than 0.001). The level of glycoprotein hormone alpha-subunit was markedly increased (20-fold) in male rats with smaller elevations in female rats. Time course studies demonstrated that increases in serum alpha-subunit levels could be detected by 24 weeks of treatment and that elevations in alpha-subunit were present in the majority of animals by 40 weeks of treatment with calcitonin. The authors conclude that high doses of calcitonin, administered to rats for 6 months or longer, increases the incidence of alpha-subunit-producing pituitary tumors.

Adenoma↗
PubMed1988

Equine juvenile mandibular ossifying fibroma.

Benign proliferative fibro-osseous lesions of the rostral mandible in six young horses are classified as equine juvenile mandibular ossifying fibroma. Histologically there is a characteristic abrupt transition from subgingival fibroblastic stroma to a zone of proliferating osteoblasts that form irregular spicules of osteoid. The layer of proliferating osteoblasts blends with a deeper zone of bony trabeculae rimmed by osteoblasts and separated by intertrabecular spaces of moderate cellular density. Incomplete surgical excision resulted in local recurrence, while rostral mandibulectomies resulted in no recurrence. The predilection for the rostral mandible of young horses coupled with the similar clinical, radiographic, and histological characteristics supports the classification of this lesion as a distinct entity.

Animals↗
PubMed1982

Fracture-associated sarcoma in the dog.

Seven fracture-associated sarcomas developed in large-breed dogs after stabilization of comminuted long bone fractures with stainless steel plates and screws. In most cases, the healing pattern of the fractures was disturbed. The mean interval between fracture occurrence and tumor diagnosis was 5.5 years. Radiographically, the sarcomas were typified by smooth-bordered subperiosteal proliferation and soft tissue mineralization. Cortical destruction was variable. Several histologic subtypes of osteosarcoma were seen. Four sarcomas had a marked inflammatory cell component and 5 of the dogs had clinical evidence of chronic infection. These findings were similar to those in 35 previously reported fracture-associated sarcomas, even though many types of fixation devices in addition to plates, as well as no fixation at all, were represented in these cases. Fracture-associated sarcomas most frequently were found to be diaphyseal, and the femur accounted for almost half of the sarcomas reported.

Animals↗
PubMed1982

Dietary Calcium and phosphorus levels for reproducing sows.

Thirty-six gilts were used to evaluate three dietary Ca/P levels over a three parity period on reproductive performance. Diets formulated to contain 14% protein with total Ca/P levels of .65/.50, .80/.60 or .90/.70%, respectively, were provided during both gestation and lactation. In each group, 10 gilts were bred and two remained unbred with diets fed at 1.8 kg/d during gestation and ad libitum during lactation. Nongravid gilts were fed 1.8 kg daily during the trial. Blood samples were collected at 60 and 100 d postcoitum and both blood and milk samples at 14 and 28 d postpartum. From each lactation and each sow group, three pigs were killed at birth and six pigs at 14 and 28 d postpartum. The rib was collected for bone ash analyses with the rib, humerus and femur collected from the progeny and examined for histopathologic lesions during the second parity. After three reproductive cycles, four sows and two unbred females/group were sacrificed and bone ash determined on femur, humerus, rib and vertebrae. The results indicated no significant difference in any sow reproductive of litter performance measurement during gestation or lactation or in milk Ca and P concentration. No histopathologic bone lesions were presented in the progeny. Sow bone ash values at the end of three reproductive cycles suggested that bone demineralization from lactating animals occurred, but not uniformly for all bones. The rib, vertebrae and humerus demineralized at a greater rate than the femur. Bone ash values for reproducing sows fed the .90/.70% Ca/p treatment for three parities were similar to those of nongravid females, which were similar for all treatment groups. The results suggested an average daily intake of 50 to 55 g Ca and 40 g P to maintain bone homeostasis in lactating sows.

Animals↗
PubMed1981

Decalcified bone grafts in the horse.

The need for early postoperative weight bearing following fracture repair in the horse has led to investigation of various means of expediting the healing process. Bone grafting represents one means of accomplishing this, and the transplantation of autologous tissues has proven to be most useful in equine orthopedics. Acid-decalcified, frozen, allogeneic bone for grafting is easy to prepare, readily contoured, osteogenic, and elicits no obvious immune or rejection response. The most compelling reason for the use of the substance is the elimination of the need of a harvesting operation on a patient already undergoing extensive surgery for the restitution of skeletal integrity.

Animals↗
PubMed1980

Effect of hyaluronic acid in naturally occurring and experimentally induced osteoarthritis.

Effect of intraarticular injections of hyaluronic acid was evaluated in two groups of horses, using force plates to assess quantitatively the degree of lameness observed. In six horses, chip fractures were created surgically on the dorsomedial aspects of both radial carpal bones. After the horses were trained for 30 days, 40 mg of hyaluronic acid was injected intraarticularly into the limb showing the greater degree of lameness. Horses were worked for 2 more weeks and then were evaluated. A highly significant (P less than 0.01) increase in weight bearing on the treated limb was observed. Ten horses with clinical unilateral front limb lameness, involving a single joint, also were treated with 40 mg of hyaluronic acid. The day after the injection, the horses resumed training and were examined 2 weeks later. At that time, the horses were free from observable lameness, and this observation was corroborated by force plate data. According to their trainers, the horses' performance improved markedly after the injection and remained improved. Seemingly hyaluronic acid was beneficial when injected into the arthritic joints of these two groups of horses.

Animals↗
PubMed1975

Electron microscopic evaluation of bone cells in pigs with experimentally induced Bordetella rhinitis (turbinate osteoporosis).

The development of osseous lesions in the nasal turbinates of pigs with experimentally induced Bordetella rhinitis, occurring 2 to 6 weeks after inoculation with Bordetella bronchiseptica strain B, was evaluated ultrastructurally, and comparisons were made with controls. Progressive degenerative changes were seen in osteoblasts and osteocytes of diseased pigs. These changes included swollen mitochondria, distention of cisternae of endoplasmic reticulum, and lysis of some cells. Bacterial organisms, believed to be B bronchiseptica, were observed in the cytoplasm of osteoblasts and inclose proximity to bone surfaces in diseased pigs. Although osteoclasts occasionally had degenerative changes in the brush border, most osteoclasts wer similar to those of control pigs. Resorption of bone adjacent to degenerative osteoblasts and osteocytes may have contributed to the development of turbinate osteoporosis when combined with the normal cellular resorptive processes. Thes ultrastructural changes were similar to those previously reported in bone cells of the nasal turbinates of pigs with experimentally induced and naturally occurring atrophic rhinitis.

Animals↗