Biomedical subjects
A McCullagh
Publications and source records attributed to A McCullagh.
Community care. Local heroes.
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A dose-finding, placebo-controlled study on extended-release felodipine once daily in treatment of hypertension.
Hypertensive patients received a beta-blocker plus placebo once daily for 4 weeks. If their diastolic blood pressure (DBP) was then 95-115 mm Hg, they were randomized to receive, in addition to the beta-blocker, placebo (n = 36), felodipine-extended release (ER) 10 mg (n = 36), or felodipine-ER 20 mg (n = 37) in a 4-week double-blind parallel-group trial. All medication was administered once daily and, when BP was measured 24 h after the last dose, felodipine-ER 10 mg reduced DBP by 14 +/- 9 mm Hg (mean +/- SD) from a mean of 103 mm Hg and felodipine-ER 20 mg reduced DBP by 18 +/- 9 mm Gg from 101 mm Hg. The reductions in DBP with both doses of felodipine were greater than reductions with placebo (5 +/- 8 mm Hg, from 102 mm Hg--both p less than 0.001). At the end of the study, 21% of patients receiving placebo had a DBP less than or equal to 90 mm Hg. In contrast, 69% of patients receiving felodipine-ER 10 mg and 82% receiving 20 mg attained this level. More than 90% of patients receiving 10 mg felodipine-ER once daily had a reduction in DBP greater than 5 mm Hg 24 h postdose. Felodipine-ER was well tolerated. Felodipine-ER once daily is an effective antihypertensive drug for patients who require therapy in addition to a beta-blocker; the tolerability in this study was good, and a starting dose greater than 10 mg once daily is not indicated.
A mathematical model for the rural amplification of Murray Valley encephalitis virus in southern Australia.
The exacerbation of epidemics of Murray Valley encephalitis in southern Australia during 1951 and 1974 was studied retrospectively to determine when viral introduction may have occurred. Data from studies spanning over 30 years were utilized 1) to determine the number of infective Culex annulirostris necessary to cause one clinical case, based on known host-feeding patterns and the subclinical infection rate in man, and 2), using mathematical modeling, to calculate the likely duration of the rural amplification phase. Generalized tables were generated which demonstrated that mosquito longevity, extrinsic incubation period, and duration of the feeding cycle were the most important variables predisposing rapid amplification. Although Murray Valley encephalitis transmission may still occur during adverse conditions when the reproduction rate Z less than 1.0, subtraction of the durations of incubation in man prior to clinical onset and the most likely rural amplification period from the dates of onset of clinical infections during January 1951 and 1974 suggested that amplification commenced around October 9-30 and that any Murray Valley encephalitis introduction had occurred by then. Examination of bird and mosquito dispersal prior to this time suggests that long-range dissemination of the virus from endemic northern Australia was unlikely.