Biomedical subjects
C Babcock
Publications and source records attributed to C Babcock.
Vascular interactions of serotonin and norepinephrine in renal hypertensive rabbits.
Vascular responses to norepinephrine (NE) are potentiated in the presence of serotonin (5-HT) and are attenuated by previous exposure to 5-HT. This study was designed to determine whether alterations in the interactions of these agonists occur in renal hypertension. Helical strips of femoral artery from two-kidney, one clip (2K1C) hypertensive and control rabbits were mounted in muscle baths for isometric force recording. Arterial strips from 2K1C rabbits were more sensitive to 5-HT than were those of control rabbits. The sensitivities of these two groups of vessels to NE were not significantly different. The 5-HT potentiation of NE was present at lower 5-HT concentrations in vessels from 2K1C rabbits than in those from control rabbits. Previous exposure to 5-HT attenuated NE responses of arteries from 2K1C less than it did those of control rabbits. Although 5-HT had little effect on loading of cellular stores of calcium in the resting muscle, previous 5-HT exposure attenuated calcium influx during an NE response, and this attenuation was not as great in vascular smooth muscle from the hypertensive animal as it was in that from the normotensive control. These results indicate that in vascular smooth muscle cells from 2K1C rabbits the potentiating action of 5-HT is increased, due to the increased sensitivity to this agonist, and the attenuating action is decreased due to a greater calcium influx during NE stimulation.
Dietary therapy slows the return of hypertension after stopping prolonged medication.
This study asks whether prolonged antihypertensive therapy will "cure" a substantial percent of rigorously treated hypertensive patients and whether nutritional change will add an antihypertensive effect and reduce the relapse rate. Of 584 eligible patients normotensive while receiving therapy, 496 were randomized into control and discontinued-medication groups with and without dietary intervention. At 56 weeks, 50% of those who were no longer receiving medication remained normotensive by study criteria. Randomization either to weight-loss group (mean loss of 4.5 kg [10 lb]) or to sodium-restriction group (mean reduction of 40 mEq/day) increased the likelihood of remaining without drug therapy, with an adjusted odds ratio of 2.17 for the sodium group and 3.43 for the weight group. Highest success rates were in the nonoverweight mild hypertensives with sodium restriction (78%) and the overweight mild hypertensives who were reducing their weight (72%). These data demonstrate that weight loss or sodium restriction, in hypertensives controlled for five years, more than doubles success in withdrawal of drug therapy.
Ascertainment of vital status through the National Death Index and the Social Security Administration.
Ascertainment of the vital status of individuals is of central importance to epidemiologic studies which monitor mortality as an end point. Utilizing identifying information collected in 1973-1974, the Hypertension Detection and Follow-up Program, a prospective, multicenter study, followed 25,362 individuals to determine eight-year mortality. In the most recent follow-up, there were 617 individuals whose vital status was not known. Available identifying information on these and on all 1,322 participants known to have died in 1979-1981 was submitted to the National Death Index (NDI) for possible confirmation of vital status. A subset of individuals who had Social Security numbers (490 lost to follow-up and 1,154 known deaths) was also submitted to the Social Security Administration (SSA). The NDI correctly identified 87.0% of the known deaths. Of the 1,154 known deaths (those with known Social Security numbers) submitted to both agencies, the NDI identified 93.1% and the SSA 83.6%. Significant variations by race and sex were noted in the identification rates, in part because of Social Security number discrepancies. False matches through the NDI matching process occurred for 10.4% of the known deaths. In the more restrictive SSA search, only 0.5% false matches resulted. For those lost to follow-up, vital status was ascertained in 57.1%. This paper describes the relative efficacy and attributes of the use of these systems to ascertain vital status.
Effective dietary intervention in hypertensives: sodium restriction and weight reduction.
A Dietary Intervention Study of Hypertension (DISH) was undertaken to determine whether patients whose high blood pressure had been controlled pharmacologically for a period of more than 5 years could maintain that control with sodium restriction or weight reduction instead of drugs. Four hundred ninety-six patients, classified by degree of overweight, were randomly assigned into one of seven groups. Included were those who would be withdrawn from antihypertensive medication and receive intervention for either sodium restriction or weight reduction. After 8 weeks of intervention, an average reduction of 24-hour urinary sodium output from a baseline of 158 mEq to 106 mEq (p less than .001) and from 130 mEq to 96 mEq (p less than .01) was achieved for the overweight and nonoverweight groups, respectively. That decline was still maintained at 56 weeks. Dietary estimates, obtained by analysis of 3-day food records, underestimated urinary output by an average of 12%, with blacks more likely to underestimate than whites, and the overweight more likely to underestimate than the nonoverweight. An average 10-lb weight loss was achieved, with no difference between men and women. Weight declined for 32 weeks, then leveled off and was maintained up to 56 weeks, indicating that sodium intake modification can be accomplished faster than weight reduction. Modest sodium restriction and weight reduction are feasible and achievable in a free-living population and have a positive effect on control of hypertension.
Acute pressure changes and possible secondary tissue changes due to laser or xenon photocoagulation.
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