Hepes may stimulate cultured endothelial cells to make growth-retarding oxygen metabolites

Summary Zwitterion buffers are often used to modulate the pH of cell culture medium but their effect on cultured cells is controversial. We found that addition of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) caused superoxide dismutase (SOD) inhibitable increases in nitroblue tetrazolium dye reduction and SOD and catalase inhibitable decreases in the growth of cultured bovine pulmonary artery endothelial cells. The findings suggest that HEPES stimulates endothelial cells to make toxic oxygen metabolites that contribute to decreased cell growth. This work was supported in part by the National Institutes of Health, Colorado and American Lung Associations, Colorado and American Heart Associations, the Council for Tobacco Research, and the Kroc, Hill, Swan and Kleberg Foundations. Dr. Bowman is a Clinician Scientist Awardee of the American Heart Association.     

Turbine flowmeter vs. Fleisch pneumotachometer: a comparative study for exercise testing

The purpose of this study was to investigate the characteristics of a newly developed turbine flowmeter (Alpha Technologies, model VMM-2) for use in an exercise testing system by comparing its measurement of expiratory flow (VE), O2 uptake (VO2), and CO2 output (VCO2) with the Fleisch pneumotachometer. An IBM PC/AT-based breath-by-breath system was developed, with turbine flowmeter and dual-Fleisch pneumotachometers connected in series. A normal subject was tested twice at rest, 100-W, and 175-W of exercise. Expired gas of 24-32 breaths was collected in a Douglas bag. VE was within 4% accuracy for both flowmeter systems. The Fleisch pneumotachometer system had 5% accuracy for VO2 and VCO2 at rest and exercise. The turbine flowmeter system had up to 20% error for VO2 and VCO2 at rest. Errors decreased as work load increased. Visual observations of the flow curves revealed the turbine signal always lagged the Fleisch signal at the beginning of inspiration or expiration. At the end of inspiration or expiration, the turbine signal continued after the Fleisch signal had returned to zero. The "lag-before-start" and "spin-after-stop" effects of the turbine flowmeter resulted in larger than acceptable error for the VO2 and VCO2 measurements at low flow rates.     

Optical polarization properties of the diffraction spectra from single fibers of skeletal muscle.

The diffraction spectra of laser light from single fibers of skeletal muscle exhibit a large degree of optical depolarization. When the linearly polarized incident laser source is oriented at polarization angles between 0 less than theta less than pi/2 rad with respect to the fiber axis, the diffracted light is elliptically polarized. These results show that the phase angle of the ellipse rotates by as much as 20 degrees when the fiber is stretched from 2.4 to 3.8 microns. To further ascertain that the observed phenomenon is diffraction related, an experiment monitoring the spectra of scattered light in between diffraction orders showed this signal to be significantly more linearly polarized. These results suggest that the degree of elliptical polarization of the diffraction spectra is a sensitive probe of A-band dynamics, including changes of the anisotropic S-2 elements.     

The Effect of an Individualized Practice-Based CME Program on Physician Performance and Patient Outcomes

The Professional Competence Assurance Program (PROCAP) is an individualized educational program that examines physicians'' performance in ambulatory practice. It uses medical record review to identify deficiencies in the care process that guides development of the educational intervention. Medical care is reassessed one year later. This program was used with 51 private practitioners to assess the care of 1,229 hypertensive patients. The educational program included a computer printout comparing one physician''s performance with that of peers, readings targeted to management problems, and a conference call or group seminar with an expert stressing issues relevant to each physician''s performance. Postintervention assessment showed that physicians prescribed beta-blockers (P<.01) and vasodilators (P<.01) more often. Improvement (P<.05) occurred in the control of diastolic blood pressure (≤90 mm of mercury) and in several other criteria. These results show that well-designed, individualized continuing medical education addressing specific deficiencies can change physicians'' performance and patients'' intermediate outcome.     

Terminal Disinfection in Hospitals with Quaternary Ammonium Compounds by Use of a Spray-Fog Technique

Spray-fogging of hospital rooms with a quarternary ammonium disinfectant was found to be an effective means of reducing the number of detectable airborne and surface bacteria. The level of bacterial contamination in hospital rooms was determined before and after fogging by means of the gravitational fallout method, the petri dish swab technique, and volumetric air-sampling procedures. Rooms vacated by patients infected with staphylococci, streptococci, pseudomonads, and salmonellae were tested and found to be effectively decontaminated of most of the detectable organisms by the fogging procedure.     

A convenient pH-gradient method for the determination of the maximum and minimum pH for microbial growth

Previously existing methods for determining the pH limits for the growth of microorganisms have involved (1), the setting up of individual cultures, each having a specific pH; (2), the pH gradient plate technique devised by Sacks (1956) in which a continuous pH gradient is established in a Petri dish by means of a buffer system; and (3), the pH gradient plate technique of Zak (unpublished), in which a continuous pH gradient is established by means of an electric current. The discontinuous pH gradient technique described here provides a convenient method of determining the maximum and minimum pH at which a microorganism can grow. The technique can be used aerobically or anaerobically, and has a precision of about ± 0.1 pH unit. Data are given for several yeasts and forSerratia marcescens. In all cases, the organisms tested continued to metabolize at pH values beyond those representing the limits for growth, sometimes by as much as 0.5 pH unit. The results suggest that pH limits are unsuitable criteria in microbial classification.     

Evidence of a Monoaminergic-Cholinergic Imbalance Related to Visual Hallucinations in Lewy Body Dementia

Senile dementia of Lewy body type is characterized clinically by a relatively acute onset of fluctuating memory loss and confusion, frequently accompanied by visual hallucinations. Neurochemical analyses of temporal cortex has revealed a distinction between hallucinating and nonhallucinating patients in both cholinergic and monaminergic transmitter activities. In contrast with the cholinergic enzyme choline acetyltransferase, which was more extensively reduced in hallucinating individuals, serotonergic S2 receptor binding and both dopamine and serotonin metabolites were significantly decreased in nonhallucinating cases. These results suggest that an imbalance between monaminergic and cholinergic transmitters is involved in hallucinogenesis in the human brain.     

Homologues of catalytic domains of Cellulomonas glucanases found in fungal and Bacillus glycosidases

We demonstrate homology between the catalytic domains of exoglucanase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) from Cellulomonas fimi and those of endoxylanases (1,4-beta-D-xylan xylanohydrolases, EC 3.2.1.8) from Bacillus sp. strain C-125 and the fungus Cryptococcus albidus; and between the catalytic domains of endoglucanase (1,4-(1,3:1,4)-beta-D-glucan 4-glucanohydrolase, EC 3.2.1.4) from Cellulomonas fimi and exoglucanase II from Trichoderma reesei. These five enzymes apparently evolved by reshuffling of two catalytic domains and several substrate-binding domains.