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Biomedical subjects

R L Bernstein

Publications and source records attributed to R L Bernstein.

27 records · Page 2Linked to original sources
PubMed1981

Extracellular folate deaminase of Dictyostelium discoideum.

Folate deaminase released from cells of Dictyostelium discoideum is heterogeneous with respect to molecular weight and stability at 60 degrees C. The most heat-stable component isoelectrofocuses in a broad band at approx. pH 6. The Km value of this component for folate is approx. 7 x 10(-7)M and Mr approx. 40 000. The major portion if not all of the deaminase binds to immobilized concanavalin A and lentil lectin. Extracellular folate deaminase has a pH-optimum of approx. pH 6.0. This is higher than that of lysosomal enzymes, which are also glycoproteins released into the extracellular medium.

Aminohydrolases↗
PubMed1981

Folate deaminase and cyclic AMP phosphodiesterase in Dictyostelium discoideum: their regulation by extracellular cyclic AMP and folic acid.

Cyclic AMP and folic acid act as chemotactic factors in Dictyostelium discoideum. Both agents, when applied extracellularly, also control cell development from the growth stage to the acquisition of aggregation competence. Cyclic AMP phosphodiesterase and folate deaminase are extracellular enzymes whose activity is regulated during early differentiation of D. discoideum cells. The two enzymes help control the extracellular levels of cyclic AMP and folic acid. The substrates cyclic AMP and folic acid each increase the extracellular activity of folate deaminase as well as phosphodiesterase. The specificity of extracellular phosphodiesterase regulation by cyclic AMP indicates that the effect is mediated by specific cyclic AMP receptors rather than the catalytic site of cell surface phosphodiesterase. To some extent cyclic AMP and folic acid are interchangeable with respect to regulating differentiation and enhancing enzymatic inactivation of intercellular signals. Thus the two extracellular signals may share a common cellular pathway of signal transduction. The regulation of folate deaminase and phosphodiesterase by folic acid does not always parallel the folic acid effects on development. Pulses of folic acid stimulate development of aggregation competence, whereas a continuous flux inhibits. In contrast, either continuous flux or pulses of folic acid increase the deaminase and phosphodiesterase activities.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

Accidental needlesticks: do anesthesiologists practice proper infection control precautions?

Anesthesiologists as well as patients are at risk for acquiring blood-borne infections such as hepatitis and AIDS. We surveyed 2,530 anesthesiologists, a 10% random sample of the members of the American Society of Anesthesiologists, with a response rate of 57.1%, to determine the incidence of accidental needlestick exposure among anesthesia personnel and whether anesthesiologists are adhering to infection control guidelines to protect themselves and their patients from exposure to infectious diseases. Eighty-eight percent of respondents reported at least 1 accidental needlestick in the past 10 years; 21% received a needlestick from a high-risk patient and 4.5% a needlestick from a known HIV-positive patients. Residents reported significantly more accidental needlesticks from known HIV-positive patients (8.5%). Mucous membrane, open cut, eye, or other significant exposure to HIV-contaminated blood or body fluids was sustained by 8.34% of respondents in the past 10 years. Sixty percent of respondents reported they almost never reuse common syringes now compared with a 40.8% non-reuse rate (P < 0.001) in a similar survey on infection control practices conducted in 1990. Sixty-three percent reported they almost never reuse a vasopressor syringe compared with the 1990 non-reuse rate of 52.5% (P < 0.001). In the current survey, 39% of anesthesiologists reported reusing syringes from one patient to another and 36% reported reusing the same vasopressor syringes for different patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesiology↗