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Biomedical subjects

J S McCarthy

Publications and source records attributed to J S McCarthy.

15 recordsLinked to original sources
PubMed1978

Age-dependent closure of the patent ductus arteriosus by indomethacin.

Indomethacin has been shown to be effective in closing a patient ductus arteriosus (PDA) in small premature infants. However, the age range over which this therapy is effective remains undetermined. Eighteen infants ranging in age from 4 to 45 days were studied. All had auscultatory and clinical findings indicative of PDA. Seventeen had roentgenographic evidence of cardiomegaly and/or increased pulmonary vascular markings, and eight had ECG evidence of ventricular hypertrophy. Indomethacin was administered to most patients in two doses of 0.1 to 0.3 mg/kg 24 hours apart. In eight of 12 patients, 3 week of age or younger, the PDA closed after indomethacin therapy. Two patients had a decrease in the intensity of murmur and improvement of congestive heart failure after treatment, but the PDA did not close completely. Only patients 33 weeks of age (actual age) or younger responded to indomethacin therapy with complete ductal closure. The condition of patients 34 to 36 weeks of age improved but there was not complete closure; in patients older than 36 weeks there was no response. The data suggest an age-related mechanism for PDA closure and that treatment with indomethacin before 33 weeks of age is probably required. A role for prostaglandin in ductal patency is postulated.

Age Factors↗
PubMed1972

The effect of sulfonylurea drugs on rabbit myocardial contractility, canine purkinje fiber automaticity, and adenyl cyclase activity from rabbit and human hearts.

Long-term clinical studies have associated tolbutamide therapy with an increased incidence of cardiovascular deaths. The effects of this and other sulfonylurea drugs on contractility and rate of isolated rabbit atria, automaticity of isolated dog Purkinje fibers, and adenyl cyclase activity in particulate preparations of rabbit and human hearts were studied. At concentrations that are attained clinically, tolbutamide (10 mg/100 ml) increased contractility of driven rabbit atria to 124+/-5% of control, acetohexamide (3.9 mg/100 ml) to 140+/-5%, chlorpropamide (8.3 mg/100 ml) to 139+/-6%, and tolazamide (3.1 mg/100 ml) to 119+/-6%. These effects were accentuated in the presence of 2.5 x 10(-4) M theophylline and were not blocked by 1 x 10(-5) M propranolol. Adenyl cyclase was activated by each of these drugs at concentrations below those which increase contractility. The drugs also increased the rate and slope of phase 4 depolarization in spontaneously beating Purkinje fibers, but did not alter the spontaneous rate of isolated rabbit atria. Since inotropic and chronotropic stimulation can be deleterious in some clinical settings, these findings may be of significance in interpretation of cardiovascular mortality data.

Acetohexamide↗
PubMed1968

A damp squib?

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