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Biomedical subjects

K Crocker

Publications and source records attributed to K Crocker.

7 recordsLinked to original sources
PubMed1996

Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?

Models of biogenic carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.

Journal Article↗
PubMed1987

The antiarrhythmic effects of d-sotalol.

The antiarrhythmic properties of d-sotalol were studied in 38 patients undergoing electrophysiologic studies. Programmed electrical stimulation studies were performed in 28 men and in 10 women with a mean age of 67 years and a mean ejection fraction of 37 +/- 3%. All patients had inducible ventricular tachycardia while they were off all antiarrhythmic therapy. D-sotalol was given as a 2 mg/kg infusion over 15 minutes and did not significantly change the PR, QRS, or QTc intervals from baseline values in the group as a whole. In the group protected by d-sotalol, the percent change in the QTc interval as well as the percent change in refractoriness was significantly increased as compared to the group not protected. D-sotalol also significantly decreased heart rate. D-sotalol prevented the induction of ventricular tachycardia in 18 of the 38 patients, while significantly slowing the rate of the ventricular tachycardia in the group that could still have tachycardia provoked. Seventeen patients were tested on procainamide and only four were protected, while d-sotalol prevented the induction of ventricular tachycardia in 7 of these 17. Eleven patients were discharged on oral d-sotalol doses ranging from 100 to 400 mg twice daily. One patient died 1 month post discharge due to an acute myocardial infarction, and one patient had a cardiac arrest while on d-sotalol and survived and was switched to amiodarone therapy. The remaining nine patients are alive and well at 14 +/- 3 months. D-sotalol appears to be an effective antiarrhythmic drugs and appears to be well tolerated.

Administration, Oral↗
PubMed1976

Post--paracervical block bradycardia: its prediction and preventability.

The fetal heart rate recordings of 100 parturients given PCB with less than 200 mg. of lidocaine were reviewed. No PCB bradycardia occurred if there were no pre-PCB FHR decelerations (92 per cent accuracy). In an effort to prevent post-PCB bradycardia, atropine was given in the maternal paracervical area and also intravenously. The most effective dose was 1.0 mg. intravenously, but the prophylactic efficiency of atropine was uncertain in preventing the post-PCB bradycardia.

Anesthesia, Local↗
PubMed1975

Fetal cardiac interval recorder.

A recorder is described which is capable of continuously measuring intervals between two events of the fetal cardiac cycle, as well as functioning as a routine intrapartum monitor. We have primarily measured the interval between the R wave of the fetal ECG and the second fetal heart sound (R-S2), but the recorder is also capable of measuring R-R, R-A0 (opening of aortic valve), R-Pl (placenta), and R-Sc (scalp) intervals. In the discussion, we endeavor to show that these intervals reflect fetal cardiac performance, which is altered by drugs and acidemia.

Electrocardiography↗