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Biomedical subjects

D Godwin

Publications and source records attributed to D Godwin.

11 recordsLinked to original sources
PubMed1999

Encoding of visual information by LGN bursts.

Encoding of visual information by LGN bursts. Thalamic relay cells respond to visual stimuli either in burst mode, as a result of activation of a low-threshold Ca2+ conductance, or in tonic mode, when this conductance is inactive. We investigated the role of these two response modes for the encoding of the time course of dynamic visual stimuli, based on extracellular recordings of 35 relay cells from the lateral geniculate nucleus of anesthetized cats. We presented a spatially optimized visual stimulus whose contrast fluctuated randomly in time with frequencies of up to 32 Hz. We estimated the visual information in the neural responses using a linear stimulus reconstruction method. Both burst and tonic spikes carried information about stimulus contrast, exceeding one bit per action potential for the highest variance stimuli. The "meaning" of an action potential, i.e., the optimal estimate of the stimulus at times preceding a spike, was similar for burst and tonic spikes. In within-trial comparisons, tonic spikes carried about twice as much information per action potential as bursts, but bursts as unitary events encoded about three times more information per event than tonic spikes. The coding efficiency of a neuron for a particular stimulus is defined as the fraction of the neural coding capacity that carries stimulus information. Based on a lower bound estimate of coding efficiency, bursts had approximately 1.5-fold higher efficiency than tonic spikes, or 3-fold if bursts were considered unitary events. Our main conclusion is that both bursts and tonic spikes encode stimulus information efficiently, which rules out the hypothesis that bursts are nonvisual responses.

Action Potentials↗
PubMed1998

Oral trovafloxacin compared with intravenous cefoxitin in the prevention of bacterial infection after elective vaginal or abdominal hysterectomy for nonmalignant disease. Trovafloxacin Surgical Group.

BACKGROUND: Trovafloxacin is a new fourth-generation fluoroquinolone whose pharmacokinetics and in vitro activity suggest that it is well suited for antibiotic prophylaxis in elective hysterectomy. METHODS: In a randomized, double-blind, multicenter study, parallel groups of women 18 years of age or older received either 200 mg trovafloxacin by mouth and intravenous (i.v.) placebo or 2 g cefoxitin by i.v. infusion and placebo by mouth before elective vaginal or abdominal hysterectomy for nonmalignant disease. RESULTS: In the 103 and 97 patients in the trovafloxacin and cefoxitin groups, respectively, who were evaluable for efficacy, the prophylactic success rates at hospital discharge (96% in both groups) and 30 +/- 6 days after hysterectomy (88% and 91% in the trovafloxacin and cefoxitin groups, respectively) were statistically equivalent. Both antibiotics were well tolerated. CONCLUSION: A single oral 200 mg dose of trovafloxacin is as effective and safe as a standard cefoxitin parenteral regimen in the prevention of primary bacterial infection after elective vaginal or abdominal hysterectomy for nonmalignant disease.

Administration, Oral↗
PubMed1991

Intrapleural cisplatin and cytarabine in the management of malignant pleural effusions: a Lung Cancer Study Group trial.

Malignant pleural effusions are a common and significant problem in patients with advanced malignancies. Pleurodesis with tetracycline or other sclerosing agents is the usual treatment for malignant pleural effusions. In contrast to this approach, intrapleural chemotherapy has the potential advantage of treating the underlying malignancy in addition to controlling the effusion. Intracavitary cisplatin-based chemotherapy, which is cytotoxic rather than sclerosing, has proven safe and effective via the intraperitoneal route in ovarian cancer and malignant mesothelioma. There has been little previous experience, however, with intrapleural cisplatin-based chemotherapy. As part of a planned series of trials in malignant mesothelioma, the Lung Cancer Study Group first evaluated intrapleural cisplatin and cytarabine in patients with malignant pleural effusions from a variety of solid tumors. From April 1986 to November 1987, 46 patients with cytologically proven, symptomatic, and previously untreated malignant pleural effusions were entered on study. A single dose of cisplatin 100 mg/m2 plus cytarabine 1,200 mg was instilled into the pleural space via a chest tube, which was then immediately removed. Patients were evaluated for toxicity and response at 24 hours; 1, 2, and 3 weeks; and then monthly. No recurrence of the effusion was considered a complete response (CR). Partial response (PR) was defined as a 75% or greater decrease in the amount of the effusion on serial chest radiographs. One patient experienced reversible grade 4 renal toxicity, four patients had grade 3 hematologic toxicity, and five patients had grade 3 cardiopulmonary toxicity. The overall response rate (CR plus PR) at 3 weeks was 49% (18 of 37 patients). The median length of response was 9 months for a CR and 5.1 months for a PR. The outcome of this trial was sufficiently encouraging that this regimen has been incorporated into subsequent trials for malignant pleural mesothelioma.

Adenocarcinoma↗
PubMed1985

Sequence of the OXA2 beta-lactamase: comparison with other penicillin-reactive enzymes.

The nucleotide sequence of the unusual plasmid-mediated OXA2 beta-lactamase is presented, and compared with other beta-lactamases. The OXA2 enzyme has similar features at the presumed active site, but no other significant regions of homology with other penicillin-reactive enzymes. The active site homology may therefore represent convergent evolution of otherwise dissimilar genes.

Amino Acids↗
PubMed1985

Prognostic features of pediatric soft-tissue sarcomas.

Eight hundred ninety-two patients under 20 years of age with soft-tissue sarcomas histologically diagnosed between 1955 and 1971 (before the era of combined modality therapy) were reviewed to delineate important prognostic variables. Differing histologic findings, extent of disease at initial presentation, and site of the primary tumor correlated with prognosis; age, sex, and race did not affect survival significantly. Patients with fibrosarcomas, liposarcomas, and leiomyosarcomas had improved survival rates when compared with adults with the same histologic findings; patients with localized tumors and extremity primary sites had the best prognosis. Patients with rhabdomyosarcomas, disseminated disease, or retroperitoneal primary sites had the worst prognosis. These data suggest that some childhood sarcomas are not as aggressive as adult sarcomas or childhood rhabdomyosarcomas. Therefore they may not require the adjuvant therapy shown to be beneficial in childhood rhabdomyosarcomas.

Adolescent↗
PubMed1979

The influence of the growth environment on the stability of a drug resistance plasmid in Escherichia coli K12.

Populations of Escherichi coli K12 containing the plasmid TP120 which coded for resistance to ampicillin, streptomycin, sulphonamide and tetracycline were grown in a chemostat under carbon-limited and phosphorus-limited conditions. With time resistance to one or more of the drugs was lost, resulting in the production of mutant populations which were more competitive than the parent population. The resistance to tetracycline was always lost under both carbon and phosphorus limitations, but resistance to the other three drugs was lost only during phosphate-limited growth. Strains of E. coli which had lost resistance to one or more of the drugs were capable of higher maximum specific growth rates than the parent strain.

Anti-Bacterial Agents↗
PubMed1979

Simplified plain film screening examination for erosive otitis media.

A simplified plain film examination for erosive otitis media was evaluated in 202 ears. In most of the operated cases (86.5%), a perorbital anteroposterior and an oblique lateral were sufficiency for diagnosis. Considerable attention should be paid to the configuration of the attic-antrum area, and in particular the presence or absence of Körner's septum (the petrosquamous suture).

Adult↗
PubMed1978

A retrospective epidemiologic study of pediatric fibrosarcomas.

One hundred eighty-two patients with histologically diagnosed fibrosarcoma below the age of 19 yr reported to the End Results Section of the National Cancer Institute before 1971 were analyzed. Race, sex, and age did not significantly affect prognosis. Site of the primary lesion and extent of disease at diagnosis did significantly affect prognosis. Overall 3-yr survival was 80%, and this remained constant over the next 5 yr. Survival of patients with upper extremity lesions exceeded 90%, whereas those with retroperitoneal primary sites had 17% survival. Patients with localized disease at diagnosis had 5-yr survival of 90%, but those with disseminated disease had a median survival of 6 mo, and 22% 1-yr and 5-yr survival.

Adolescent↗