Persistence of punished escape responses.
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Biomedical subjects
Publications and source records attributed to T Chow.
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Hypoxia, an important mechanism of radioresistance, is a strong stimulus for erythropoietin (EPO) production. The stimulatory effects of EPO are mediated through the activation of its receptors, EPO receptors (EPORs). The objective of this study is to determine whether EPORs are expressed in biopsy specimens of patients with squamous cell carcinoma of the cervix. Eighteen biopsy specimens were studied after obtaining Institutional Review Board-approved consent. Standard immunohistochemistry techniques were utilized. Expression of EPORs was present in 16 out of 18 (88.9%) specimens. The intensity (qualitative) and the frequency (semiquantitative) of EPORs expression showed a statistically significant correlation (P= 0.00379). Statistical analysis was performed to determine whether EPORs expression is related to other parameters such as age, FIGO stage, histologic grade, and hemoglobin levels. Only age showed a statistically significant correlation with EPORs frequency of expression (P= 0.00878). Currently, work is in progress in our laboratory to study the radiobiologic effects of EPO on the radiation response of cultured cancer cell lines in vitro.
Commonly prescribed antiarrhythmic agents--and several recently developed agents--are reviewed with respect to their use in patients with renal failure, hepatic failure, and congestive heart failure. Because removal of electrophysiologically active agents from the systemic circulation in most cases depends on either renal elimination, hepatic metabolism, or both, patients with preexisting kidney or liver disease may be at increased risk of treatment-related drug toxicity, including proarrhythmia. These susceptibilities should be anticipated, with drug selection and/or dosage modified accordingly. Patients with left ventricular dysfunction and heart failure also are at increased risk of treatment-related complications, including proarrhythmia and hemodynamic intolerance. In addition, the metabolism of antiarrhythmic drugs may be impaired in these patients. Preference should be given to drugs with a proven safety profile, such as amiodarone, in patients with heart failure.