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Biomedical subjects

S L Wheeler

Publications and source records attributed to S L Wheeler.

34 records · Page 2Linked to original sources
PubMed1985

Efficacy and toxicity of estrogens commonly used to terminate canine pregnancy.

Three groups of bitches were treated with diethylstilbestrol (75 micrograms/kg) orally for 7 days (n = 12), estradiol cypionate intramuscularly once (22 micrograms/kg; n = 12), or estradiol cypionate intramuscularly once (44 micrograms/kg; n = 12). Treatments commenced during late proestrus (n = 4/group), the fourth day of behavioral estrus (n = 4/group), or the second day of diestrus (n = 4/group). All bitches were bred on alternate days throughout estrus to stud dogs of known fertility. Ovariohysterectomies were performed on day 25 of diestrus to diagnose pregnancy and to assess any pathologic changes in the uterus. Eleven bitches treated with diethylstilbestrol, 6 bitches treated with the low dosage of estradiol cypionate, and 4 bitches receiving the high dosage of estradiol cypionate were pregnant at the time of surgery. Ten of the bitches treated with estrogens during proestrus, 6 treated during estrus, and 4 treated during diestrus were pregnant. The serum concentration of progesterone in 2 bitches treated with the high dosage of estradiol cypionate decreased to less than 2 ng/ml by day 25 of diestrus, suggesting premature luteal regression. Diethylstilbestrol appeared to have little efficacy in terminating pregnancy. Estradiol cypionate appeared to have greater efficacy when administered during estrus or early diestrus; however, pyometra developed in 2 bitches treated with this estrogen during diestrus.

Abortion, Induced↗
PubMed1985

Serum concentrations of thyroxine, 3,5,3'-triiodothyronine, thyrotropin, and prolactin in dogs before and after thyrotropin-releasing hormone administration.

Serum concentrations of thyrotropin (TSH), prolactin, thyroxine, and 3,5,3'-triiodothyronine in 15 euthyroid dogs and 5 thyroidectomized and propylthiouracil-treated dogs after thyrotropin-releasing hormone (TRH) administration were measured. Although thyroidectomized and propylthiouracil-treated dogs had higher (P less than 0.01) base-line concentrations of TSH in serum than did euthyroid dogs, concentrations of TSH after TRH administration varied at 7.5, 15, and 30 minutes with 14 of 45 samples obtained from healthy dogs having lower TSH concentrations than before TRH challenge. Similarly, concentrations of 3,5,3'-triiodothyronine in the serum of euthyroid dogs 4 hours after TRH administration were similar (P less than 0.05) to concentrations before TRH challenge. Although the mean concentration of thyroxine in serum was elevated (P less than 0.05) 4 hours after administration of TRH to euthyroid animals, as compared with base-line levels, the individual response was variable with concentrations not changing or decreasing in 4 dogs. Therefore, the TRH challenge test as performed in the current investigation was of limited value in evaluating canine pituitary gland function. Although mean concentrations of TSH in serum were higher (P less than 0.05) in euthyroid dogs after TRH administration, the response was too variable among individual animals for accurate evaluation of pituitary gland function. Concentrations of prolactin in the sera of dogs after TRH administration, confirmed previous reports that exogenously administered TRH results in prolactin release from the canine pituitary and indicated that the TRH used was biologically potent.

Animals↗
PubMed1985

Serum concentrations of thyroxine and 3,5,3'-triiodothyronine before and after intravenous or intramuscular thyrotropin administration in dogs.

Response to thyrotropin (TSH) was evaluated in 2 groups of mixed-breed dogs. Thyrotropin (5 IU) was administered IV to dogs in group 1 (n = 15) and IM to dogs in group 2 (n = 15). Venous blood samples were collected immediately before administration of TSH and at 2-hour intervals for 12 hours thereafter. In group 1, the maximum mean concentration (+/- SD) of thyroxine (T4; 7.76 +/- 2.60 micrograms/dl) and 3,5,3'-triiodothyroxine (T3; 1.56 +/- 0.51 ng/ml) was attained at postinjection hours (PIH) 8 and 6, respectively. However, the mean concentration of T4 at PIH 6 (7.21 +/- 2.39 micrograms/dl) was not different (P greater than 0.05) from the mean concentration at PIH 8. The maximum mean concentration of T4 (10.10 +/- 3.50 micrograms/dl) and T3 (2.22 +/- 1.24 ng/ml) in group 2 was attained at PIH 12 and 10, respectively. Because dogs given TSH by the IM route manifested pain during injection, had variable serum concentrations of T3 after TSH administration, and may require 5 IU to achieve maximal increases in serum T4 concentrations, IV administration of TSH is recommended. The optimal sampling time to observe maximal increases in T3 and T4 after IV administration of TSH was 6 hours. Repeat IV administration of TSH may cause anaphylaxis and, therefore, is not recommended.

Animals↗
PubMed1984

Rat eustachian tube synthesizes disaturated phosphatidylcholine.

Otitis media results when the eustachian tube fails to adequately ventilate the middle ear. A surface tension-lowering substance may be required for normal tube opening, especially in young children with poorly developed naso-pharyngeal musculature. We report here that rat eustachian tube epithelium synthesizes disaturated phosphatidylcholine, which is recognized as the surface tension-lowering substance of pulmonary surfactant.

Animals↗
PubMedDate not supplied

Ureterocolonic anastomosis in ten dogs with transitional cell carcinoma.

Ureterocolonic anastomosis (UCA) was performed in 10 dogs with transitional cell carcinoma of the urinary bladder trigone or the urethra, or both. All grossly visible tumor was excised. All of the dogs recovered from anesthesia and surgery and had anal continence with no urine leakage. One dog died of undetermined causes 7 days after surgery. Nine dogs survived 1 to 5 months. The owners of eight of the dogs considered their dog's quality of life to be acceptable. Four dogs were euthanatized because of neurologic disease, three of which also had nausea and vomiting. The neurologic and gastrointestinal signs may have been caused by hyperammonemia, metabolic acidosis, and uremia. Blood ammonia levels were elevated in two dogs with neurologic signs. Hyperchloremic metabolic acidosis that was reversible with bicarbonate therapy was diagnosed in five dogs. All of the dogs were azotemic because of intestinal recycling of urea. Serum creatinine concentrations increased in four dogs after surgery. Drug-induced renal disease may have developed in two dogs. Pyelonephritis developed in five kidneys, two of which had outflow obstruction and two had bilateral hydroureteronephrosis before the UCA. In this small number of dogs, surgical excision of transitional cell carcinoma was not curative with six dogs having confirmed metastatic lesions at the time of death.

Anastomosis, Surgical↗
PubMedDate not supplied

A syndrome resembling lymphomatoid granulomatosis in the dog.

Lymphomatoid granulomatosis (LYG) was diagnosed in seven dogs. Most of the affected dogs were young to middle-aged, and there was no breed or sex predilection. Basophilia was detected in six of the seven dogs. Radiographic abnormalities included lung lobe consolidation or pulmonary mass lesions, as well as abnormally large tracheobronchial lymph nodes. Histologic changes included angiocentric and angiodestructive pulmonary infiltrates characterized by large lymphoreticular and plasmacytoid cells as well as normal lymphocytes, eosinophils, and plasma cells. Five dogs were treated with combination chemotherapy, and three had a complete response to treatment.

Animals↗
PubMedDate not supplied

Alterations in carbohydrate metabolism in canine lymphoma.

Following an overnight fast, blood samples were obtained from 14 dogs with previously untreated lymphoma before and 5, 15, 30, 45, 60, and 90 minutes following an intravenous challenge with 500 mg/kg dextrose. Samples were assayed for glucose, lactate, and insulin concentrations and compared statistically with ten control dogs of similar weight and age undergoing an identical dextrose challenge. Dogs with lymphoma had similar glucose tolerance curves when compared with controls. Lactate concentrations were significantly higher (P less than 0.001) at baseline and all time periods of the glucose tolerance test in dogs with lymphoma when compared with controls. Rise in lactate concentrations over baseline levels in the first 30 minutes of the glucose tolerance test were significantly higher in dogs with lymphoma (P = 0.011). Insulin concentrations were significantly higher (P less than 0.001) at baseline and at the 5-, 45-, 60-, and 90-minute time periods of the glucose tolerance test in dogs with lymphoma. Rise in insulin concentrations over baseline in the first 5 minutes of the glucose tolerance test were also significantly greater in dogs with lymphoma (P = 0.021). These results indicate carbohydrate metabolism is altered in dogs with lymphoma. Many of these alterations parallel those observed in human patients suffering from cancer cachexia making canine lymphoma a potential model for further study of the pathogenesis and therapy of cancer cachexia.

Animals↗
PubMedDate not supplied

Exacerbation of hyperlactatemia by infusion of lactated Ringer's solution in dogs with lymphoma.

Blood lactate concentrations and acid-base status of six dogs with lymphoma were compared statistically with those from six healthy control dogs before, during, and after a 6-hour infusion of lactated Ringer's solution (LRS). Blood lactate concentrations in dogs with lymphoma were significantly (P less than 0.05) higher immediately before, and at the 1-, 2-, 4-, and 6-hour time periods after infusion when compared with controls. Blood lactate concentrations increased significantly (P = 0.016) after the first hour of infusion in dogs with lymphoma but did not increase in the control dogs. The increase in blood lactate concentrations over baseline values after 1 hour of LRS infusion was significantly (P = 0.008) greater in dogs with lymphoma when compared with controls. Blood lactate concentrations returned to baseline levels after 2 hours of infusion in dogs with lymphoma, suggesting that dogs with lymphoma have a transient inability to handle increased lactate loads when compared with controls. However, the potential to augment lactate use, clearance, or both is present and does occur over time. Blood gas values were not significantly altered within the lymphoma or control dog groups after 6 hours of LRS infusion. Blood bicarbonate concentrations in dogs with lymphoma were significantly decreased before and after LRS infusion when compared with controls.

Acid-Base Equilibrium↗
PubMedDate not supplied

Pheochromocytoma in 50 dogs.

Fifty dogs with pheochromocytoma were identified in a retrospective study of a 9-year period. For 24 of 50 dogs (48%), the tumor was an incidental finding during necropsy or surgery. Presenting signs were referrable to the nervous system in 7 of the 26 symptomatic dogs (27%); were referrable to the cardiopulmonary system in 7 of 26 dogs (27%); or were nonspecific, reflecting general systemic disease, in 17 of 26 dogs (65%). Abnormal clinical findings were highly varied but were also generally referrable to the cardiopulmonary and nervous systems. Six of 7 dogs (86%) evaluated were hypertensive (systolic range, 164 to 325 mm Hg; diastolic range, 110 to 198 mm Hg). Serum biochemical findings were nonspecific, although 11 of 39 dogs (28%) were hypercholesterolemic. Abdominal fluid samples were analyzed in 6 dogs; 3 were nondiagnostic, and 3 were interpreted as lymphosarcoma. The imaging studies that were of most value included abdominal radiographs (mass identified in 9 of 16 dogs [56%]), caudal vena caval angiography (tumor thrombus correctly diagnosed in 4 of 7 dogs [57%]), and abdominal ultrasonography (mass seen in 5 of 6 dogs [83%] and tumor thrombus seen in 3 of 5 dogs [60%]). Local tumor invasion was present in 26 of 50 dogs (52%), regional lymph node metastases in 6 of 50 dogs (12%), and distant metastases in 12 of 50 dogs (24%). Cause of death was tumor-related in 19 of 50 dogs (38%) and non-tumor related in 28 of 50 dogs (54%).

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Bone marrow cytological findings in 4 dogs and a cat with hemophagocytic syndrome.

Hemophagocytic syndrome or hemophagic histiocytosis was diagnosed in 4 dogs and 1 cat by evaluation of bone marrow aspirate smears. One of the dogs had a suspected infection with canine parvovirus and a confirmed infection with Salmonella spp, 2 dogs had presumptive diagnoses of myeloproliferative and lymphoproliferative disease, respectively, and 1 dog died without a diagnosis. The cat had hepatic lipidosis and lesions compatible with feline calicivirus infection. All animals had cytopenias involving 2 or more cell lines, and fragmented erythrocytes in the blood, along with mild to moderate increases in the number of macrophages in the bone marrow. Numerous marrow macrophages contained phagocytized hematopoietic cells. Other cytological features of the bone marrow were variable in each patient, but the degree of response in the blood was inadequate, even in those with bone marrow hyperplasia. The phagocytosis of hematopoietic elements did not appear to be caused by a primary immune disorder, but rather by the inappropriate activation of normal macrophages secondary to infectious, neoplastic, or metabolic diseases. These findings suggest that hemophagocytic syndrome may be an important factor in the development of cytopenias; the data also support the cytological evaluation of bone marrow aspirates as an aid in the diagnosis of hemophagocytic syndrome.

Animals↗
PubMedDate not supplied

Tissue preservation and maintenance of optimum esthetics: a clinical report.

Today, most tooth replacement in the esthetic zone is done using implants placed in a delayed surgical protocol. Unfortunately, this delay can result in loss of both hard and soft tissue during the healing period, necessitating guided tissue regeneration techniques at the time of implant placement. Recent developments with tapered implants have facilitated predictable immediate implant placement, preserving the osseous structure surrounding the socket. Further developments with custom healing abutments can preserve the crestal soft tissues, including the papillae. This article reviews techniques that provide for the preservation of both bone and soft tissue while enhancing the esthetic results around implants.

Bicuspid↗
PubMedDate not supplied

Eight-year clinical retrospective study of titanium plasma-sprayed and hydroxyapatite-coated cylinder implants.

A total of 1,202 press-fit cylinder implants were placed in 479 patients from March 1986 to March 1994. The patients' ages ranged from 14 to 88 years. The implants included 889 titanium plasma-sprayed implants and 313 hydroxyapatite-coated implants. There were no statistically significant differences in the distribution of hydroxyapatite-coated and titanium plasma-sprayed implants based on implant location, type of restoration, age, and sex. Although differences in long-term success rates based on simple percentages were also not statistically significant, cumulative survival rates based on life table analysis up to 96 months were 92.7% for titanium plasma-sprayed systems and 77.8% for hydroxyapatite-coated systems. Graphical interpretations of these data revealed interesting contrasts, including the timing and results of implant failure, which are discussed in detail.

Adolescent↗
PubMedDate not supplied

Six-year clinical and histologic study of sinus-lift grafts.

This study retrospectively evaluated the results of 36 sinus-lift graft augmentations performed to place 66 implant cylinders in the posterior maxilla where vertical bone height was less than ideal. Grafts were accomplished with porous hydroxyapatite (HA) alone, porous HA mixed with autogenous bone removed from the iliac crest, and HA combined with autogenous bone removed from within the mouth. Nineteen core biopsy specimens were taken from different grafts at time intervals ranging from 4 to 36 months from the time of grafting. These cores were evaluated using histomorphometric analysis to yield data comparing volume fractions of bone formation, allowing comparison of different graft materials and healing times. Grafts using porous HA alone on mean produced 16.38% bone by volume after 6 months. After the same healing time, grafts using HA and hip bone on mean produced 19.30% bone by volume compared with an 11.30% bone volume when using HA and bone harvested intraorally. Evaluation of cores taken at 19 and 36 months revealed greater volumes of bone formation. Recommendations based on clinical and histologic results are discussed in detail.

Adolescent↗