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Biomedical subjects

F W Bell

Publications and source records attributed to F W Bell.

At least 19 recordsLinked to original sources
PubMed1998

Randomized controlled trial of doxorubicin versus dactinomycin in a multiagent protocol for treatment of dogs with malignant lymphoma.

OBJECTIVE: To compare efficacy and toxicity of 2 multiagent chemotherapeutic protocols similar in all respects except that 1 incorporated dactinomycin and the other incorporated doxorubicin for treatment of dogs with malignant lymphoma. DESIGN: Randomized controlled trial. ANIMALS: 45 dogs with malignant lymphoma. PROCEDURE: Dogs were randomly assigned to a doxorubicin or dactinomycin treatment group. Time to first remission, duration of first remission, survival time, and prevalence of toxicoses, particularly number of episodes of dose-limiting neutropenia and gastrointestinal toxicoses, were compared between groups. RESULTS: 37 dogs received at least 1 dose of doxorubicin (21 dogs) or dactinomycin (16). Median time to first remission was not significantly different between groups, but median duration of first remission and median survival time were significantly longer for dogs in the doxorubicin treatment group than for dogs in the dactinomycin treatment group. Number of dogs that died, number of episodes of dose-limiting neutropenia, and number of episodes of gastrointestinal toxicoses were not significantly different between groups. CLINICAL IMPLICATIONS: A multiagent chemotherapeutic protocol incorporating doxorubicin was significantly more effective in dogs with malignant lymphoma than a similar protocol incorporating dactinomycin. Despite the lower cost and lack of cardiotoxicity, dactinomycin is not an equivalent substitute for doxorubicin in the initial treatment of dogs with malignant lymphoma.

Animals↗
PubMed1997

Prostatic intraepithelial neoplasia in dogs with spontaneous prostate cancer.

Prostatic intraepithelial neoplasia (PIN) is the most likely precursor of human prostate cancer. The prevalence and immunophenotype of PIN in dogs with spontaneous prostate cancer has not been previously described. To investigate the association between PIN and prostate cancer, we evaluated the prostates of dogs with spontaneous prostate carcinoma. The prevalence of PIN was determined in formalin-fixed prostates from 29 dogs with spontaneous prostate cancer. Using immunoperoxidase techniques, we compared basal cell layer integrity (high molecular weight keratin 34 beta-E12), proliferative index (MIB-1), and microvessel density (Factor VIII-related antigen) in 14 prostates which contained benign epithelium, PIN, and carcinoma. PIN was present in 19 of 29 (66%) prostates from dogs with spontaneous prostate cancer. The basal cell layer was intact in benign epithelium, disrupted in 72% of acini with PIN, and absent in carcinoma. The mean proliferative index was 17%, 25%, and 40% for benign epithelium, PIN, and carcinoma, respectively, and these differences were significant. The mean microvessel density in foci of PIN and carcinoma (32 and 39 vessels per mm2, respectively) was greater than in benign epithelium (23 vessels per mm2). High-grade PIN is common in the prostates of dogs with spontaneous carcinoma. The basal cell layer is partially disrupted in PIN, whereas it is absent in prostate cancer. The proliferative index and microvessel density of PIN are intermediate between benign epithelium and cancer. These results are similar to those reported for human PIN and prostate cancer, and indicate that PIN is part of a morphologic continuum in the progression of prostate cancer. To our knowledge, this is the first description of high-grade PIN spontaneously occurring in animals. The canine prostate may serve as a useful model for examining factors that modulate PIN and prostate cancer progression.

Animals↗
PubMed1995

Phenethylthiazolethiourea (PETT) compounds, a new class of HIV-1 reverse transcriptase inhibitors. 1. Synthesis and basic structure-activity relationship studies of PETT analogs.

A novel series of potent specific HIV-1 inhibitory compounds is described. The lead compound in the series, N-(2-phenethyl)-N'-(2-thiazolyl)thiourea (1), inhibits HIV-1 RT using rCdG as the template with an IC50 of 0.9 microM. In MT-4 cells, compound 1 inhibits HIV-1 with an ED50 of 1.3 microM. The 50% cytotoxic dose in cell culture is > 380 microM. The chemical structure-activity relationship (SAR) was developed by notionally dividing the lead compound in four quadrants. The SAR strategy had two phases. The first phase involved optimization of antiviral activity through independent variation of quadrants 1-4. The second phase involved the preparation of hybrid structures combining the best of these substituents. Further SAR studies and pharmacokinetic considerations led to the identification of N-(2-pyridyl)-N'-(5-bromo-2-pyridyl)-thiourea (62; LY300046.HCl) as a candidate for clinical evaluation. LY300046.HCl inhibits HIV-1 RT with an IC50 of 15 nM and in cell culture has an ED50 of 20 nM.

Animals↗
PubMed1995

The PETT series, a new class of potent nonnucleoside inhibitors of human immunodeficiency virus type 1 reverse transcriptase.

To identify the minimal structural elements necessary for biological activity, the rigid tricyclic nucleus of the known human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitor tetrahydroimidazobenzodiazepinthione was subjected to systematic bond disconnection to obtain simpler structures. A rational selection and testing of modeled analogs containing these potential pharmacophoric moieties led to the discovery of a new series of nonnucleoside inhibitors of RT. The lead compound of this new PETT series of nonnucleoside RT inhibitors, N-(2-phenylethyl)-N'-(2-thiazolyl)thiourea (LY73497), was found to inhibit HIV-1 but not HIV-2 or simian immunodeficiency virus in cell culture at micromolar concentrations. This derivative was also found to inhibit HIV-1 RT. Through an integrated effort involving synthesis and molecular modeling, compounds with nanomolar potency against HIV-1 in cell culture were developed. In these studies, LY300046-HCl was identified as a potent nonnucleoside inhibitor of HIV-1 RT possessing favorable pharmacokinetic properties.

Animals↗
PubMed1993

Discovery and structure-activity relationship of a series of 1-carba-1-dethiacephems exhibiting activity against methicillin-resistant Staphylococcus aureus.

The synthesis and antimicrobial activity of several new 1-carba-1-dethiacephalosporins is described. The discovery of unique activity of some of the analogues against methicillin-resistant Staphylococcus aureus led to the development of a structure-activity relationship designed to optimize this activity. The results of this investigation along with the pharmacokinetic characteristics of select compounds are described.

Animals↗
PubMed1991

Clinical and pathologic features of prostatic adenocarcinoma in sexually intact and castrated dogs: 31 cases (1970-1987).

The medical records of 31 dogs diagnosed with prostatic carcinoma at the teaching hospital between January 1970 and October 1987 were reviewed to determine whether gender status had an effect on the clinical features or biologic behavior of the disease. The only significant difference between sexually intact and castrated dogs was increased prevalence of pulmonary metastasis in castrated dogs.

Adenocarcinoma↗
PubMed1990

Hypercalcemia in two cats with squamous cell carcinomas.

Hypercalcemia was identified in 2 cats with squamous cell carcinomas. One cat was referred because of multiple cutaneous tumors; the second cat had metastatic disease from an oral squamous cell carcinoma. In both cats, serum immunoreactive midmolecule parathyroid hormone concentration was within the range determined for clinically normal cats. The high serum calcium concentration in these cats may have resulted from the neoplastic disease, as evidenced by the reduction in serum calcium concentration after decrease in tumor size in response to treatment, and by failure to identify other known causes of hypercalcemia.

Animals↗
PubMed1987

Neoplastic diseases of the thorax.

Thoracic neoplasia comprises a heterogeneous group of diseases, many of which are distinctly uncommon in veterinary medicine. These diseases often present the clinician with diagnostic and therapeutic challenges. Careful diagnostic work-up and staging are essential for consideration of therapeutic options and formulation of prognosis. Neoplastic diseases of the thorax are classified here as tracheal tumors, primary lung tumors, nonrespiratory intrathoracic tumors, and thoracic wall tumors.

Animals↗
PubMed1986

Canine distal renal tubular acidosis and urolithiasis.

Distal RTA is characterized by decreased distal renal tubular hydrogen ion secretion, decreased ability to acidify urine, hypercalciuria, hyperphosphaturia, hypocitraturia, and metabolic acidosis. Because of the resulting alterations in urine composition and pH, patients with distal RTA are predisposed to urolithiasis and renal calcification. Diagnosis of distal RTA is important because it is a potentially reversible disorder that, left untreated, may cause nephrocalcinosis, recurrent urolith formation, moderate to severe metabolic acidosis, and renal failure.

Acidosis, Renal Tubular↗