Biomedical subjects
Publications and source records attributed to D Harris.
The present study was designed to investigate possible residual effects of delayed auditory feedback on paragraph readings performed by normal speaking college students. No residual effect was shown under any of the experimental conditions employed.
A programmable microprocessor has been developed to control a nerve stimulator, to accept electromyographic potentials and to process them to produce derivatives related to neuromuscular function which can then be stored and displayed. Examples are given of its use to assess the physiological state of the neuromuscular junction and to quantify the degree of blockade in clinical situations.
To construct acid-base curves and alignment nomograms for swine blood, we added known amounts of acid or base to aliquots of swine blood with three different concentrations of hemoglobin. Pairs of blood samples were equilibrated at two different CO2 partial pressures, and blood pH was measured. Data were analyzed by computer, and mean values were created for complete data of four swine. Curve and alignment nomograms were constructed by computer. The resultant nomograms for swine blood differ from those constructed by Siggaard-Andersen for human blood, most importantly at base-excess values of +10 to +25 mmol/l. The possible reasons for the observed differences are discussed and, although not completely resolved, may be related in large measure to the accuracy of pH determination and the methodology of nomogram construction.
The stability of lingual vibrotactile magnitude scales produced by the method of magnitude production was investigated for 10 adult subjects. These subjects produced highly stable magnitude scales across two test sessions separated by 1 wk. The subjects appeared to use absolute rather than ratio scales in the magnitude-production task. A discussion of the stability of the scales is conducted with reference to the likelihood of an internal, absolute mechanism for magnitude scaling.
Intramodal range has been studied by R. Teghtsoonian (1973), who found that for magnitude-estimation procedures an increase in the scaling range will cause a decrease in the exponent of the power function. For magnitude production procedures, an increase in the scaling range will decrease the magnitude of the exponent of the power function (Teghtsoonian, 1973). The purpose of this pilot study was to investigate the influence of scaling range on the psychophysical functions obtained by the method of magnitude production for vibrotaction. Twenty subjects were randomly selected and divided into two groups of 10 subjects each. Subjects' ages ranged from 17 to 23 yr. A detailed description of the vibrotactile equipment can be found elsewhere (1). The psychophysical method of magnitude production was used to establish suprathreshold magnitude functions from the anterior midline section of the tongue dorsum and the thenar eminence of the right hand. Each subject in Group 1 received a random order of six numbers (5, 10, 15, 20, 25, 30) and was asked to adjust the magnitude of the stimulus that he was feeling to the number being presented. Each subject in Group 2 received the same random series of six numbers as Group 1, but other numbers were also randomly interspersed above, between, or below the series of six to present an expanded range of numbers for scaling. For both groups the randomized series of numbers was presented three times at each test site.(ABSTRACT TRUNCATED AT 250 WORDS)
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Experiments were performed on nine dogs instrumented with pulmonary artery Swan-Ganz catheters and catheters placed into the distal aorta and posterior caval vein. Electromagnetic flowmeter probes were placed around the portal vein and hepatic artery, and the portal vein was cannulated. A week later, systemic and splanchnic circulatory variables were studied before and after 10 mg/kg of midazolam given intravenously. Three minutes after injection, heart rate increased 26% (P less than 0.006), cardiac index decreased 15% (P less than 0.001), portal flow increased 19% (P greater than 0.05), and hepatic arterial flow decreased slightly (P less than 0.002). Later, portal blood flow decreased 17% below baseline values (P less than 0.006). The biphasic response of portal blood flow to midazolam is probably related to redistribution of blood within the splanchnic system (blood mobilization from spleen and intestine). It is suggested that because maintenance of cardiac output during midazolam anesthesia depends on compensatory mechanisms, failure to increase cardiac output with compensatory increases in heart rate, contractility, and blood volume mobilization from the splanchnic circulation could result in decreased cardiac output.
Fifty-one patients with advanced metastatic carcinoma of the prostate were treated with the antiestrogen tamoxifen. Thirty-eight of these patients were refractory to prior hormonal manipulation with estrogens and/or orchiectomy, and five (13%) achieved an objective response (partial regression or stable disease using the National Prostate Cancer Project criteria). Median survival of the responders was significantly longer than that of the nonresponders (P less than 0.05). An additional 13 patients who had not previously received hormonal manipulation were treated with tamoxifen; one partial response and three disease stabilizations were noted. Response was separately evaluated for 15 patients with objectively measurable lesions using standard Phase II response criteria. Only 1/15 (7%) partial response and 3/15 (20%) disease stabilizations were documented. Subjective benefit in terms of significant pain relief was noted in 17/50 (34%) of patients. Toxicity was mild, but two possible "tumor flares" were noted. These results do not support the continued investigation of tamoxifen in advanced carcinoma of the prostate.
Myocardial imaging was performed at rest and after dipyridamole infusion using 201Tl and 99Tcm - gated blood pool studies (MUGA). Of 38 patients studied, 21 had coronary artery disease (CAD) and 17 were normal. With 201Tl imaging, 19 of 21 patients with CAD (sensitivity 88%) showed perfusion defects during dipyridamole. Of 17 normals 6 (specificity 65%) showed clear perfusion defects during dipyridamole. With MUGA, 2 of 15 patients with CAD (sensitivity 13%) developed abnormal wall motion during dipyridamole; both patients developed ST depression greater than 1 mm. Of 10 normals none developed abnormal wall motion. Twenty six of 38 patients developed angina during dipyridamole, which was reversed by aminophylline in 24 of 26. We suggest that dipyridamole infusion is effective for 201Tl-perfusion imaging, and easily performed, but is not suitable for MUGA studies where ischaemia is the required endpoint.
This study investigates the effects of ultrasound on fresh tendon repairs in rabbits. It is our conclusion that ultrasound adversely affects the early healing process.
Aldicarb, a carbamate pesticide, was detected for the first time in groundwater in Suffolk County, New York, in August 1979. Although all laboratory and field studies indicated that the pesticide could not reach groundwater, a combination of circumstances allowed its residues not only to reach groundwater but also to be ingested by humans. Inquiries in hospitals and poison control centers did not reveal any cases of carbamate poisoning. The extensive monitoring program, conducted by the County in cooperation with the federal and state agencies and the Union Carbide Corporation, showed that 1,121 (13.5 per cent) of the 8,404 wells examined exceeded the state recommended guidelines of 7 ppb. Of the contaminated wells 52 per cent contained adicarb between 8 and 30 ppb, 32 per cent between 31 and 75 ppb, and 16 per cent more that 75 ppb. Residents whose wells exceeded the guideline were advised not to use the water for drinking or cooking purposes and to obtain an alternate source of potable water. The Union Carbide Corporation provided those residents with activated carbon filtration units. The incident raises several serious issues, such as the testing of pesticides under field conditions prior to registration and during their use, the validity of the recommended actionable levels, and the paucity of long-term epidemiologic studies of the health effects resulting from consumption of pesticides in trace concentrations.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Four methods of calculating left ventricular ejection fraction from equilibrium radionuclide angiography have been assessed for inter-observer variability and compared to single-plane contrast cineangiography. The superiority of data-processing methods which use a left ventricular region of interest which follows the changing size of the left ventricle into systole is demonstrated. A simple method of correcting for background is suggested as an alternative for those centres not possessing the necessary software for methods involving a changing region of interest.