Biomedical subjects
Publications and source records attributed to K A Anderson.
Nitrate preparations are useful in the treatment of acute and chronic angina, acute and chronic congestive heart failure, and acute myocardial infarction. Development of tolerance is best managed by providing a nitrate-free interval, thus avoiding continuous drug levels. This interval probably should be 10 to 12 hours with use of a transdermal patch. Nitrate treatment of the elderly may require lower doses to avoid hypotension.
We evaluated DNA flow cytometry of urine histogram profiles as a screening procedure for bladder cancer. To establish the false-positive rate, we first studied a low-risk group of 90 patients with no history of bladder cancer: 24 with benign prostatic hyperplasia and 66 with upper tract stones, and found 4.4% unsatisfactory and 15.1% abnormal histograms. Urine samples were then obtained for 54 additional patients (most being evaluated for benign prostatic hyperplasia) whose selection was based on their smoking habits. These included 20 nonsmokers, 10 who had not smoked for at least 20 years (mean: 18 packs/year) and 24 current smokers (mean: 71 packs/year). Abnormal histograms were obtained for 14% of nonsmokers and for 36% of smokers, a group known to be at risk for developing bladder cancer. Although abnormal histograms are more frequent for smokers, the background false-positive rate remains unacceptably high for general screening purposes.
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A case of diffuse, epithelioid mesothelioma of the right pleura in a 16-year-old boy is presented. Though a history of previous exposure to asbestos could not be elicited, the patient did receive pulmonary irradiation for metastatic Wilms' tumor at the age of 2 years. The authors believe that the development of his mesothelioma was causally related to his prior radiotherapy.
Possible interactions between three calcium entry blocking agents (nifedipine, verapamil and bepridil) and the non-depolarizing neuromuscular blocking agent, vecuronium bromide, were investigated in chloralose-anaesthetized cats. In i.v. doses which caused decreases in arterial pressure, the calcium entry blockers did not affect indirectly-elicited twitches of tibialis muscle, but did potentiate the effects of vecuronium. No such potentiation of vecuronium was observed with the vasodilator drug, sodium nitroprusside. Experiments using close-arterial injections of acetylcholine suggested that the probable site of interaction is on the postsynaptic muscle membrane and probably involves blockade of calcium channels in skeletal muscle.
Rapid mixing-vesicle ion flux and planar lipid bilayer-single channel measurements have shown that a high-conductance, ligand-gated Ca2+ release channel is present in 'heavy', junctional-derived membrane fractions of skeletal and cardiac muscle sarcoplasmic reticulum. Using the release channel-specific probe, ryanodine, a 30S protein complex composed of polypeptides of Mr approximately 400,000 has been isolated from cardiac and skeletal muscle. Reconstitution of the complex into planar lipid bilayers has revealed a Ca2+ conductance with properties characteristic of the native Ca2+ release channel.