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Biomedical subjects

R C Klein

Publications and source records attributed to R C Klein.

16 recordsLinked to original sources
PubMed1992

Detecting removable surface contamination.

Although surveying for radioactive contamination by wiping surfaces is the norm, this practice can be highly variable and may be inefficient for detecting low-energy beta emitters. Relying on wipe testing may likewise be an inefficient use of personnel and may seriously underrepresent the amount of contamination present. In general practice, it is better to clean and, where applicable, renew surfaces regularly as part of standard operating protocols and work practices.

Equipment Contamination↗
PubMed1991

Salt restriction lowers resting blood pressure but not 24-h ambulatory blood pressure.

Dietary salt restriction is the most common therapeutic recommendation given to hypertensives, but past studies have assessed the effect of salt restriction using resting blood pressure (BP) measurements not with the newer technique of 24-h ambulatory BP monitoring. We compared the effect of high (250 mEq Na/day) and low (10 mEq Na/day) salt diets on resting versus ambulatory BP in 12 normal and 15 hypertensive subjects. Each diet was given for 7 days. Ambulatory BP was monitored from day 6 to day 7 of each diet; resting supine BP was measured on the morning of day 8. In normal subjects, neither resting nor ambulatory BP changed with sodium restriction. In hypertensives, resting BP fell 14 +/- 3/6 +/- 2 mm Hg (systolic/diastolic; P less than .01 for both) with sodium restriction while ambulatory BP fell only 4 +/- 2/2 +/- 2 (P = NS). The resting BP fall was significantly greater than the ambulatory BP fall (P less than .05) for both systolic and diastolic pressure. Ambulatory heart rates were also significantly greater during sodium restriction, suggesting that the low salt diet activated the sympathetic nervous system. This may, in turn, have partially offset the hypotensive effect of sodium restriction. We conclude that using resting BP to assess the effect of sodium restriction may overestimate the efficacy of this therapy. Ambulatory BP monitoring should be employed in future studies of sodium restriction.

Ambulatory Care↗
PubMed1991

Management of mixed wastes from biomedical research.

Mixed radioactive and chemical wastes generated by biomedical research were characterized, and various treatment methods for reducing their volume were evaluated. These wastes consist primarily of organic solvents used in the extraction and purification of radiolabeled biomolecules that are contaminated with low levels of the long-lived radionuclides, 3H and 14C. The Rockefeller University's mixed wastes fall into three broad chemical categories: phenol/chloroform, acetonitrile/water, and mixtures of miscellaneous solvents such as carbon tetrachloride, benzene, and other hazardous chemicals. Currently, with the exception of liquid scintillation cocktails (deregulated in 1981), there are no commercial disposal outlets for mixed wastes nor may they be stored legally for more than 90-180 d. Most of these mixed wastes can be effectively rendered into nonradioactive chemical and aqueous radioactive waste, both of which can be disposed of in accordance with existing regulations. However, to do so requires a Resource Conservation and Recovery Act (RCRA) Part B permit for licensure as a treatment, storage, and disposal facility. For many university research facilities, this may require financial and personnel resources disproportionate to the small amounts of waste produced. Also, such treatment, if not done properly, presents potential occupational hazards from the direct handling of waste materials. Deregulation of certain mixed wastes would be the safest, most cost-effective, and practical method for dealing with many mixed wastes of biomedical origin. In any event, a national regulatory solution must be found.

Hazardous Substances↗
PubMed1990

Virus penetration of examination gloves.

Examination gloves worn for protection from biohazards were sampled and evaluated for their ability to exclude virus particles. We found that thin gloves manufactured from polyethylene or polyvinyl chloride are ineffective barriers while gloves of thin latex are superior but not without failure. Polyethylene and polyvinyl chloride gloves had failure rates of 40% and 22%, respectively. Following exposure to the common disinfectant, 70% ethanol, these failure rates increased to 94% and 56% for polyethylene and polyvinyl chloride gloves, respectively. Latex, although permeable to ethanol, was penetrated by virus less than 1% of the time regardless of whether the latex had been pre-exposed to disinfectant or not. This study highlights the need for caution on the part of those who rely upon examination gloves for protection from infectious agents as well as the need for establishing more adequate standards and testing procedures for their manufacture.

Ethanol↗
PubMed1989

Use of electrophysiologic testing in patients with nonsustained ventricular tachycardia: prognostic and therapeutic implications.

Forty patients with coronary artery disease and nonsustained ventricular tachycardia on ambulatory electrocardiographic monitoring underwent programmed electrical stimulation. In 22 patients, monomorphic ventricular tachycardia was induced at baseline drug-free electrophysiologic testing; 9 of these patients subsequently developed a clinical sustained ventricular tachyarrhythmia. In 18 patients, no tachycardia could be induced, and none of these 18 had subsequent tachycardia. In 25 of the 40 patients, arrhythmia management was guided by the results of electrophysiologic testing; this group included 11 patients who received antiarrhythmic therapy for induced ventricular tachycardia and 14 patients without inducible ventricular tachycardia who did not receive antiarrhythmic therapy. In the remaining 15 patients, arrhythmia management was not based on the results of electrophysiologic testing. Only two episodes of clinical sustained tachyarrhythmia occurred in the group receiving electrophysiologically guided therapy compared with seven episodes in the group treated without electrophysiologic guidance (p less than 0.01). Thus, in patients with coronary artery disease with nonsustained ventricular tachycardia on ambulatory electrocardiography, electrophysiologic testing can identify those at high and low risk for subsequent clinical tachycardia events. Furthermore, results of such testing can be used to optimize arrhythmia management in these patients.

Adult↗
PubMed1989

Comparison of antihypertensive therapies by noninvasive techniques.

We compared the antihypertensive effects of the beta-blocker atenolol and the converting enzyme inhibitor lisinopril during 12 weeks of treatment in patients with mild to moderate essential hypertension. Atenolol (n = 10) significantly decreased conventionally measured blood pressure from 144/103 to 135/93 mm Hg and lisinopril (n = 9) from 150/104 to 130/92 mm Hg. Based on data derived from automated 24-h ambulatory blood pressure monitoring, atenolol decreased the average whole-day systolic pressure by 18 +/- 6 mm Hg (p less than 0.02) and the diastolic pressure by 11 +/- 2 mm Hg (p less than 0.01). Lisinopril produced decreases of 27 +/- 5 mm Hg (p less than 0.01) and 13 +/- 2 mm Hg (p less than 0.001). Examination of the 24-h blood pressure patterns showed that the efficacies of the two drugs were similar. Each appeared to be effective throughout the whole-day monitoring period, although only lisinopril significantly decreased blood pressure during the final four-h period (4 AM to 8 AM) preceding the next day's dose. Neither drug produced significant echocardiographic changes in left ventricular wall thickness or muscle mass during the short-term treatment. Lisinopril and atenolol effectively decrease blood pressure during a 24-h period. Moreover, we found that automated whole-day blood pressure monitoring is a useful tool for comparing the efficacy and duration of action of differing antihypertensive agents.

Adult↗
PubMed1979

Recent advances in programmable pacemakers. Consideration of advantages, longevity and future expectations.

The important electrical characteristics of conventional ventricular demand pacemakers currently widely employed are unable to be altered by noninvasive means after their implantation. However, a number of domestic pacemaker manufacturers have started to introduce a new modality for atraumatic modulation of these devices, the fully programmable pacemaker system, whereby the several variables regulating pacemaker operation may be optimized on an individual basis according to need. Such programmable pacemaker functions which can be varied include rate, energy output, refractory period and sensing threshold. The indications, significance and mechanisms for control of the various function programming are delineated for physician understanding at the present time.

Arrhythmias, Cardiac↗
PubMed1978

Papillomatosis of the respiratory tract. Upper airway obstruction and carcinoma.

Metastasizing squamous cell carcinoma of the lung developed in a patient who had juvenile papillomatosis but had had no previous radiation therapy. At the same time, a significant upper airway obstruction was present. All endobronchial lesions rapidly resolved with radiation therapy, and the carcinoma was resected.

Adolescent↗
PubMed1978

Influenza, respiratory distress and clear chest films: report of four cases.

Four patients developed severe wheezing and dyspnea with clear chest films during the course of an influenza epidemic. A variety of factors appeared to play a role in the pathogenesis of the respiratory distress. Standard bronchodilator therapy produced no appreciable response. All patients did well with supportive care.

Adult↗
PubMed1978

Incremental intravenous nitroglycerin for control of afterload during anesthesia in patients undergoing myocardial revascularization.

In 25 patients undergoing coronary artery bypass grafting hemodynamic measurements (including values obtained with Swan-Ganz catheterization in 21 of the patients) were made before and after administering a bolus injection of 64 or 96 mcg of nitroglycerin to relieve intraoperative hypertension. This pharmacological agent reduced afterload and preload without raising heart rate. The effect was apparent within 1-3 min and lasted 5-10 min. Untoward hypotension was not encountered in any instance. This intervention appears to be a safe approach to the treatment of intraoperative hypertension in patients with coronary artery disease.

Adult↗