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Biomedical subjects

C S Black

Publications and source records attributed to C S Black.

7 recordsLinked to original sources
PubMed1997

Renal dose dopamine does not alter the response to beta-adrenergic stimulation by isoproterenol in healthy human volunteers.

OBJECTIVES: To determine if renal dose dopamine (3 microg/kg/min) alters the heart rate (HR) by itself, or if a dopamine infusion alters the HR response to bolus doses of the beta-adrenergic agonist isoproterenol in healthy human subjects. DESIGN: Prospective study. SETTING: Clinical laboratory of a university-affiliated academic medical center. SUBJECTS: A total of 15 healthy nonpregnant women and men aged 21 to 44 years. INTERVENTIONS: Subjects were monitored continuously with bedside ECG, pulse oximetry, and ambulatory ECG recording to measure the maximal HR response to separate injections of 10, 20, and 30 ng/kg of isoproterenol, given before, during, and after the infusion of 3 microg/kg/min of dopamine. MEASUREMENTS AND MAIN RESULTS: Dopamine in the absence of isoproterenol did not alter baseline HR significantly (62.7+/-2.2 beats/min without dopamine; 65.4+/-2.2 with dopamine; p=0.15). All three doses of isoproterenol increased HR significantly above baseline, both in the presence and absence of dopamine (p<0.001). Dopamine infusion resulted in a higher HR following isoproterenol only for the 20-ng/kg dose. The incremental increases in HR, defined as the difference between peak HR following isoproterenol and baseline HR, were not increased during dopamine infusion for any of the doses of isoproterenol. Nausea was reported by 5 of the 15 subjects during the dopamine infusion. CONCLUSIONS: In healthy human subjects, infusion of 3 microg/kg/min of dopamine does not significantly increase the HR when combined with beta-adrenergic stimulation using isoproterenol, suggesting neither an additive nor antagonistic interaction between the two drugs. While our study did not demonstrate an increase in HR in healthy subjects, the risk of increasing the chronotropic response to beta-adrenergic inotropic medications with "renal dose" dopamine in critically ill patients needs to be investigated. The frequency of nausea during dopamine infusion also may influence consideration of using dopamine to augment splanchnic blood flow and renal function in conscious patients.

Adrenergic beta-Agonists↗
PubMed1996

Volumetric assessment of preload in trauma patients: addressing the problem of mathematical coupling.

The availability of the volumetric thermodilution pulmonary artery catheter allows preload assessment based on ventricular volume rather than pressure. This technique has been shown clinically to be a better measure of preload than the pulmonary artery occlusion pressure (PAOP). Critics of the technique argue that the use of thermodilution to measure cardiac output (CO) accounts for the better correlation between right ventricular end-diastolic volume (RVEDV) and CO than PAOP and CO, since stroke volume derived from the CO is a common term to both RVEDV and CO. Previous studies have attempted mathematical corrections for this coupling effect, but direct comparisons using a nonthermodilution measure of CO have not been reported. Our objective was to evaluate the importance of mathematical coupling between RVEDV and CO by assessing the ability of RVEDV to predict CO measured by thermodilution (COTH) compared with CO simultaneously determined by the Fick principle (COFICK). We performed a prospective study of 53 consecutive trauma patients admitted to a Level I trauma center between 10/1/94 and 6/1/95 who received a volumetric pulmonary artery catheter. Using linear regression analysis, RVEDV and PAOP were correlated with simultaneous measurements of both COFICK determined via indirect calorimetry and COTH. Fisher's z-transformation was used to evaluate the correlation coefficients for significant differences (p < .05). The correlation coefficients for RVEDV vs. COTH and RVEDV vs. COFICK were similar (.48 vs. 0.45, p = .76). There was a significant correlation between COTH and COFICK (r = .74, p < .001). RVEDV was significantly better than PAOP at predicting both COTH (p < .001) and COFICK (p = .04). Multivariate regression analysis confirmed that RVEDV was the only estimate of preload which was significantly related to CO. We conclude that mathematical coupling does not have a significant clinical effect on the relationship between RVEDV and CO.

Blood Pressure↗
PubMed1984

Effect of antisperm antibodies in serum and cervical mucus on the capacity of human sperm to penetrate zona-free hamster ova.

Human sera with elevated titers of antisperm antibodies reduced the capacity of human sperm to penetrate zona-free hamster ova. Of 111 sera examined, 33 (30%) reduced the mean percentage of ova penetrated to less than 52%, which was significantly different from the overall control mean (75%). Three sera reduced the penetration of ova to 7% or less. The inhibitory effect of these three sera was still present in their respective Fab preparations. An analysis of antibody effects revealed that the presence of sperm-immobilizing antibodies had a significantly greater influence on sperm penetration capacity than agglutinating antibodies. Sperm motility per se appeared to be unaffected by the different sera. Sperm treated with cervical mucus (CM) samples generally exhibited a lesser degree of ova penetration than did sperm treated with serum or medium alone. Among CM groups, however, samples containing detectable sperm-immobilizing antibody activity or samples from women with circulating antisperm antibody caused significant reductions in sperm penetration capacity.

Animals↗
PubMed1979

Effects of antisera on human sperm penetration of zona-free hamster ova.

Human sperm, after treatment with a 10% concentration of rabbit or rhesus monkey normal sera and antisera, were evaluated for fertilizing potential by incidence of zona-free hamster ova penetrated by the sperm as evidenced by the presence of swollen sperm heads and male pronuclei. Compared with the basic medium alone, treating sperm with normal sera tended to increase the percentage of ova penetrated whereas antisera against sperm, sperm extract, and testis caused significant decreases in ova penetrated. A Fab preparation of these antisera exhibited similar inhibitory effects. Antisera Fab treatment of the zona-free ova prior to exposure to sperm had no effect on penetration rate.

Animals↗