Biomedical subjects

S Madhavan

Publications and source records attributed to S Madhavan.

At least 73 records · Page 4Linked to original sources

PubMed1994

Ethnicity and the relationship of sodium intake to blood pressure.

OBJECTIVE: To examine the impact of race on the relationship between sodium intake and blood pressure. METHODS: We examined the blood pressure levels and 24-h urinary sodium excretion of 808 (355 Black, 453 Caucasian) union members who participated in a workplace hypertension control program. The 808 study subjects, who met the criterion for accuracy of urine collection, included 627 untreated hypertensives (systolic blood pressure > or = 160 mmHg or diastolic blood pressure > or = 95 mmHg, or both) and 181 normotensives (blood pressure < 160/95 mmHg). RESULTS: In univariate analysis, the age-adjusted mean diastolic blood pressure levels of the Black subjects exceeded those of the Caucasian subjects at a significance level that was marginal for the male and very high for the female subjects. No differences were observed in mean systolic blood pressure between the Black and Caucasian subjects. Within each racial grouping, the subjects were grouped by sex-specific tertile of urinary sodium excretion in order to compare baseline characteristics and blood pressure levels. Small differences between the Black and Caucasian males in age-adjusted blood pressure within each urinary sodium excretion category were further diminished after adjusting for confounding factors. Significant differences between the Black and Caucasian females in age-adjusted diastolic blood pressure within each urinary sodium excretion group became non-significant when further adjusted for weight or body mass index, or both. These findings are in agreement with those observed in multiple linear regression models. CONCLUSION: In this socio-economically homogeneous group, when confounding factors are considered, Black and Caucasian subjects have similar blood pressure levels at the same level of 24-h urinary sodium excretion. Ethnicity itself was not found to influence the relationship between sodium intake and blood pressure.

Adult↗

PubMed1994

Consumers' preference and willingness to pay for pharmacist counselling for non-prescription medicines.

Pharmacist counselling for non-prescription medicine purchases is one way of ensuring that these medicines are used in a safe and effective manner. Data collected as part of a larger study of information sources on non-prescription medicines were used to determine consumers' preference for pharmacist counselling for non-prescription medicine purchases, their willingness to pay for the service, and the amount they were willing to pay. A total of 458 (15.2%) consumers from six contiguous states in the U.S.A. responded to the mailed questionnaire. Of the consumers who responded, 63.4% indicated a preference for such a counselling service and, of these consumers, 20.4% indicated a willingness to pay for the service. Of the consumers who indicated a willingness to pay for pharmacist counselling for non-prescription medicines, 56.5% were willing to pay between 50 cents and $1.50, 28.2% between $1.51 and $3, and about 15.3% were willing to pay more than $3. Significant differences were noted in consumers' preference for pharmacist counselling when compared on the basis of certain consumer characteristics. Consumers who indicated a preference for pharmacist counselling for non-prescription medicines showed a significantly higher involvement in non-prescription medicine purchase decision, perceived pharmacists to be more credible, and indicated more favourable previous encounters with pharmacists than consumers who did not prefer pharmacist counselling. Consumers who consulted pharmacists and usually accepted their recommendations were also more likely to prefer pharmacist counselling for non-prescription medicines.

Adult↗

PubMed1994

Relation of pulse pressure and blood pressure reduction to the incidence of myocardial infarction.

The prognostic value of pretreatment pulse pressure as a predictor of myocardial infarction and the relation of pulse pressure and in-treatment diastolic blood pressure reduction to myocardial infarction were investigated in a union-sponsored systematic hypertension control program. In a prospective study, 2207 hypertensive patients with a pretreatment systolic blood pressure greater than or equal to 160 mm Hg and/or diastolic pressure greater than or equal to 95 mm Hg grouped according to tertile of pulse pressure (PP1, < or = 46; PP2, 47 to 62; PP3, > or = 63 mm Hg) were further stratified by the degree of diastolic fall: large (L), > or = 18; moderate (M), 7 to 17; small (S), < or = 6 mm Hg. During an average follow-up of 5 years, 132 cardiovascular events (50 myocardial infarctions, 23 strokes) were observed. Myocardial infarction rates per 1000 person-years were positively related to pulse pressure (PP1, 3.5; PP2, 2.9; PP3, 7.5; PP3 versus PP1, P = .02). Wide pulse pressure was identified as a predictor of myocardial infarction (PP3 versus [PP1 + PP2]: relative risk [RR] = 2.2, 95% confidence interval [CI] = 1.2-4.1), controlling for other known risk factors by Cox regression. A curvilinear relation (resembling a J shape) between diastolic fall and myocardial infarction was observed in patients with the widest pulse pressure, PP3 (L, 9.5; M, 3.9; S, 11.2; L versus M: RR = 2.5, 95% CI = 1.0-6.2; S versus M: RR = 2.9, 95% CI = 1.1-8.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

The determinants of hypertension awareness, treatment, and control in an insured population.

OBJECTIVES: The purpose of the study was to identify the determinants of awareness, treatment, and control of hypertension in a population with full access to medical care. METHODS: Unionized New York City health care workers (n = 1394) with comprehensive medical insurance were screened for hypertension. Union records documenting all physician visits and prescription medications for the year before screening provided the opportunity to relate patterns of treatment to blood pressure outcomes. RESULTS: Of the 409 employees found to have hypertension, 289 (71%) were aware of their condition and 201 (49%) had been treated, but only 51 (12%) had their blood pressure controlled at the recommended level (< 140/90 mm Hg). In a logistic regression model, the only variable of treatment associated with control was days of antihypertensive medication. The total number of physician visits was not associated with control. CONCLUSIONS: These findings demonstrate that in conventional community settings, even in the absence of financial barriers, treatment for hypertension continues to be characterized by poor outcomes. Improving access to primary care, without changes in the nature of that care, may not substantially improve blood pressure control.

Aged↗

PubMed1994

Consumer involvement in nonprescription medicine purchase decisions.

As self-medication with nonprescription drugs becomes increasingly popular and important in this era of escalating health care costs and growing consumer sophistication, the degree of consumer involvement in the purchase decision becomes an important factor. High involvement suggests active information-seeking behavior and, therefore, a greater likelihood of appropriate nonprescription drug use. The authors assess consumer involvement in nonprescription medicine purchase decisions and the use of expert sources of information.

Community Participation↗

PubMed1993

A prospective study of HIV-seropositive asymptomatic women of childbearing age in a developing country.

An observational study of 140 HIV-seropositive asymptomatic women of childbearing age was conducted in Haiti from 1984 to 1992 as part of a larger natural history study. Forty-four women were pregnant or became pregnant during the study period. The progression to HIV-related disease, AIDS, and mortality from AIDS was compared in the pregnant and nonpregnant cohorts. The mean follow-up time was 44 months. Overall, 32 of the 140 women (38%) developed AIDS, and 26 (19%) died from AIDS during the study period, with a cumulative AIDS incidence rate of 16% at 3 years after study entry. There was a trend toward earlier manifestation of HIV-related symptoms among the pregnant cohort, but no significant difference was observed in the rate of progression to AIDS or death between the pregnant and nonpregnant women.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Association of the renin-sodium profile with the risk of myocardial infarction in patients with hypertension.

BACKGROUND: To test the prognostic value of plasma renin activity prospectively, we determined the pretreatment renin-sodium profile of 1717 subjects with mild-to-moderate hypertension (mean age, 53 years; 36 percent white; 67 percent men) in a systematic work-site treatment program. METHODS: Renin profiles, obtained by plotting plasma renin activity against the urinary excretion of sodium, were classified as high (12 percent of the subjects), normal (56 percent), and low (32 percent), and there were expected variations according to age, sex, and race. Modified stepped-care treatment for hypertension, prescribed without reference to the renin profile, was similar in the three renin groups. RESULTS: Mean (+/- SD) blood pressure at entry was 151 +/- 19/100 +/- 10 mm Hg in the subjects with a high renin profile, 151 +/- 19/97 +/- 10 mm Hg in those with a normal profile, and 151 +/- 20/96 +/- 11 mm Hg in those with a low profile. During 8.3 years of follow-up, there were 27 myocardial infarctions. As adjusted for age, sex, and race, the incidence of myocardial infarction per 1000 person-years was 14.7 among the subjects with a high renin profile, 5.6 among those with a normal profile, and 2.8 among those with a low profile (rate ratio for high vs. low, 5.3; 95 percent confidence interval, 3.4 to 8.3). The rate of mortality from all causes was 9.3 in the high-profile group, 5.3 in the normal-profile group, and 3.9 in the low-profile group. The independent association of a high renin profile with myocardial infarction (but not with stroke or noncardiovascular events) was affirmed by Cox analyses (rate ratio for high vs. normal plus low, 3.2; 95 percent confidence interval, 1.2 to 8.4) after adjustment for race, sex, age at entry, serum cholesterol level, smoking status, electrocardiographic evidence of left ventricular hypertrophy, blood glucose level, body-mass index, history of cardiovascular disease or treatment, blood pressure, and use of beta-blockers. CONCLUSIONS: In the study population, whose blood pressure before and during treatment was in a narrow range, and after other cardiovascular risk factors had been considered, the renin profile before treatment remained independently associated with the subsequent risk of myocardial infarction.

Blood Pressure↗

PubMed1990

Blood pressure reactivity predicts myocardial infarction among treated hypertensive patients.

High blood pressure (BP) defines a prognostically heterogeneous group. Because BP varies according to time, setting and means of observation, it has been postulated that BP reactivity might better predict cardiovascular disease (CVD) than does unidimensional measurements. To assess BP reactivity, the difference between pretreatment nurse (RN) and physician (MD) diastolic BP (DBP)--systematically recorded in that order--or MD-RN DBP, was obtained in 1737 previously untreated patients with sustained, RN BP greater than or equal to 160 and/or 95 mmHg. Patients stratified by tertiles of MD-RN DBP [(I) less than or equal to - 3, (II) -2 to 3 and (III) greater than or equal to 4 mmHg] were similar by sex, race, age, body mass index, cholesterol, electrocardiography, prior CVD, smoking and pretreatment or attained in-treatment BPs. During 14 years of followup, myocardial infarction (MI) incidence per 1000/year were, tertile I (3.2), II (3.7), III (7.6) (relative risk = 2.4, III vs I + II, p less than 0.05), whereas stroke incidence and non-CVD mortality were evenly distributed. By Cox survival analysis, controlling for other entry characteristics only age, sex and DBP reactivity remained predictive (p less than or equal to 0.03) of MI or total CVD. Thus, BP reactivity, probably a centrally-mediated phenomenon, identifies a subgroup of hypertensives with an increased propensity for MI despite successful BP control.

Adult↗

PubMed1990

The Enzymatic Synthesis of Rubber Polymer in Parthenium argentatum Gray.

Washed rubber particles isolated from stem homogenates of Parthenium argentatum Gray by ultracentrifugation and gel filtration on columns of LKB Ultrogel AcA34 contain rubber transferase which catalyzes the polymerization of isopentenyl pyrophosphate into rubber polymer. The polymerization reaction requires Mg(2+) isopentenyl pyrophosphate, and an allylic pyrophosphate. The K(m) values for Mg(2+), isopentenyl pyrophosphate, and dimethylallyl pyrophosphate were 5.2 x 10(-4) molar, 8.3 x 10(-5) molar, and 9.6 x 10(-5) molar, respectively. The molecular characteristics of the rubber polymer synthesized from [(14)C]isopentenyl pyrophosphate were examined by gel permeation chromatography on three linear columns of 1 x 10(6) to 500 Angstroms Ultrastyragel in a Waters 150C Gel Permeation Chromatograph. The peak molecular weight of the radioactive polymer increased from 70,000 in 15 minutes to 750,000 in 3 hours. The weight average molecular weight of the polymer synthesized over a 3 hour period was 1.17 x 10(6) compared to 1.49 x 10(6) for the natural rubber polymer extracted from the rubber particles. Over 90% of the in vitro formation of the rubber polymer was de novo from dimethylallyl pyrophosphate and isopentenyl pyrophosphate. Treatment of the washed rubber particles with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate solubilized the rubber transferase. The solubilized enzyme(s) catalyzed the polymerization of isopentenyl pyrophosphate into rubber polymer with a peak molecular weight of 1 x 10(5) after 3 hours of incubation with Mg(2+) and dimethylallyl pyrophosphate. The data support the conclusion that the soluble preparation of rubber transferase is capable of catalyzing the formation of a high molecular weight rubber polymer from an allylic pyrophosphate initiator and isopentenyl pyrophosphate monomer.

Journal Article↗

PubMed1989

Treatment-induced blood pressure reduction and the risk of myocardial infarction.

To examine the relationship between degree of treatment-induced blood pressure (BP) reduction and myocardial infarction, the experience of 1765 previously untreated, mild to moderate hypertensives (initial BP greater than or equal to 160 and/or greater than or equal to 95 mm Hg) in a systematic treatment program was reviewed. Over an average of 4.2 years, there were 39 morbid or fatal myocardial infarctions. Three types of fall in diastolic BP (final minus pretreatment) were defined: small (less than or equal to 6 mm Hg), moderate (7 to 17 mm Hg), and large (greater than or equal to 18 mm Hg). By Cox regression, an association was observed between myocardial infarctions and both a large and a small fall, relative to a moderate decline. Age and sex were independent risk factors. Body mass index, cholesterol level, electrocardiogram, race, prior cardiovascular disease, smoking status, initial and final revisit BP, total intreatment BP, and systolic BP were not. Since both a large and small reduction in diastolic BP were associated with a higher incidence of myocardial infarction (relative to a moderate fall), perhaps a moderate reduction in diastolic BP should be the goal of treatment for mild and moderate hypertensives.

Blood Pressure↗

PubMed1989

Lead in soil: recommended maximum permissible levels.

Lead in soil has been recognized as a public health problem, particularly among children. In recent years, attention has been directed to cumulative adverse effects of lead at low levels of intake. Lead-contaminated soil and dust have been identified as important contributors to blood lead levels. Based on available data on blood lead and lead in soil, an approach has been developed to suggest a permissible level of lead in soil, below which there will be reasonable certainty that adverse health effects will not occur. An acceptable level of 600 ppm of lead in soil suggested as a "safe" level would contribute no more than 5 micrograms/dl to total blood lead of children under 12 years of age. Maximum permissible levels of lead in soil have been recommended based on the dose-response relationship of lead in soil and blood lead in children.

Administration, Oral↗

PubMed1989

Stimulation of Isopentenyl Pyrophosphate Incorporation into Polyisoprene in Extracts from Guayule Plants (Parthenium argentatum Gray) by Low Temperature and 2-(3,4-Dichlorophenoxy) Triethylamine.

Rubber particles isolated from guayule (Parthenium argentatum Gray) stem homogenates contain a polyprenyl transferase which catalyzes the polymerization of isopentenyl pyrophosphate into polyisoprene. The polymerization reaction is stimulated with the addition of an allylic pyrophosphate initiator and forms a polymer of polyisoprene with a molecular weight distribution from 10(3) to 10(7). The polymerization reaction in crude stem homogenates is not affected by the addition of an initiator probably due to the high activity of isopentenyl pyrophosphate isomerase furnishing saturating levels of dimethylallyl pyrophosphate. Polyisoprene formation in stems of guayule plants exposed to cold winter temperatures increased from 15.4 milligrams per gram dry weight in October to 24.5 milligrams per gram dry weight in January and increased from 16.2 to 38.1 milligrams per gram dry weight in the same period by additionally treating the plants with 5000 ppm of 2-(3,4-dichlorophenoxy)triethylamine. The rate of polymerization of isopentenyl pyrophosphate into polyisoprene in stem homogenates of the cold treated plants increased from 12.1 nanomoles per hour per gram fresh weight in October to 144.3 nanomoles per hour per gram fresh weight in January and increased from 17.7 to 446.8 nanomoles per hour per gram fresh weight in the same period by additionally treating the plants with 5000 ppm of 2-(3,4-dichlorophenoxy)triethylamine. These results show that the increase in polyprenyl transferase activity partially accounts for the increase in polyisoprene synthesis in guayule plants exposed to low temperature and treated with 2-(3,4-dichlorophenoxy)triethylamine.

Journal Article↗

PubMed1989

Impact of race on treatment response and cardiovascular disease among hypertensives.

To determine the effect of race on cardiovascular disease occurrence among treated hypertensive patients, the experience of 1,807 black and 2,962 white hypertensive patients who entered a union/management--sponsored, worksite-based treatment program (1973-1985), was evaluated. Participants had similar socioeconomic profiles, equal access to health benefits, and received standard treatment. Median duration of observation was 42 months. Blacks had 48, and whites 129, of the 177 morbid (strokes and heart attacks) or mortal cardiovascular disease outcomes. At baseline, blacks had more electrocardiographic abnormalities (32% vs. 19%, p less than 0.0001), lower mean cholesterol (218 vs. 230 mg%, p less than 0.001), smoked more (35% vs. 30%, p less than 0.001), and were less likely to be treated for hypertension before entering the program (53% vs. 58%, p less than 0.01) than whites. They were also more likely than whites to belong to unions employing less skilled workers (p less than 0.0001). Overall, all-cause mortality rates between the races were similar. However, total cardiovascular disease morbidity and mortality rates were 10.5 (whites) and 6.4 (blacks) per 1,000 person years (p less than 0.005); the difference was largely explained by higher myocardial infarction rates among older (55 years or older) white men (15.6 vs. 7.5, p less than 0.05). That advantage was not present amongst younger black persons. In fact, blacks lost more years of life before age 65 (102 vs. 64 years/1,000 persons, p less than 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

PubMed1989

Estrogen replacement therapy: a pilot survey of primary care physicians in West Virginia.

Controversy surrounds the optimal use of estrogen replacement therapy (ERT) for the management of vasomotor instability and other perimenopausal symptoms. This fact and the obvious lack of published literature regarding physician prescribing behavior led the investigators to explore these issues with primary care physicians in West Virginia. Data were collected using a mailed, self-administered questionnaire. Issues addressed included reasons for using/not using ERT, patient symptoms, type of therapy prescribed, treatment duration, and symptom resolution or rebound. Approximately 25 percent of the 420 physicians contacted responded to the questionnaire. The overwhelming majority prescribes ERT for their patients. Most physicians prescribe an estrogen/progesterone combination for some or all patients, depending on the clinical situation. Conjugated estrogens in physiologic doses and synthetic progestins are most frequently prescribed and administered on a cyclic basis. Most women prescribed ERT experienced symptom resolution. Treatment outcome was not correlated with treatment duration.

Adult↗

PubMed1989

Pharmacists' evaluations of the nonprescription availability of metaproterenol, cimetidine, ibuprofen, and nystatin.

The relative importance of six switch evaluation criteria in pharmacists' evaluations of the appropriateness of switching four drugs from prescription to nonprescription status was assessed. A questionnaire was constructed for three potential switch candidates (metaproterenol, cimetidine, and nystatin) and one already switched drug (ibuprofen 200 mg). Pharmacists were asked to judge (1) the overall appropriateness of switching these four drugs and (2) the appropriateness of switching these drugs based on the FDA switch criteria of safety, effectiveness, and labeling and two other proposed criteria: the need for oral counseling about the product and perceived market need for the product. Additionally, pharmacists were asked to rate whether they believed the study drugs would be profitable to their pharmacies if the drugs were switched to nonprescription status. A total of 1161 pharmacists were reached by the mailings, of whom 417 (34.8%) responded. Only ibuprofen 200 mg received a positive overall switch approval rating from the pharmacists; cimetidine received the lowest rating. The six evaluation criteria were tested for significant association with pharmacists' overall judgment of the appropriateness of switching each drug. The three most influential criteria were safety, labeling, and market need for the product, respectively. Profitability to the pharmacy was not significantly associated with pharmacists' overall judgment of switch appropriateness. Regression analysis identified safety, labeling, and market need as important in the evaluation of all four drugs, and pharmacists' evaluation of the relative importance of these criteria was a predictor of their overall judgment of the appropriateness of a switch. Consumer safety, not personal economic interests, most influenced pharmacists' judgment of the appropriateness of a switch from prescription to nonprescription status for four drugs.

Attitude of Health Personnel↗

PubMed1986

Renin relationship to sex, race and age in a normotensive population.

The relationship of renin activity to sex, race (black or white) and age (less than 50 or greater than or equal to 50 years of age) was examined in 236 normal subjects measure yearly for up to 9 years. There were 58 white women (34 less than 50 years, 24 greater than or equal 50 years), 66 white men (30 less than 50 years, 36 greater than or equal to 50 years), 57 black women (34 less than 50 years, 23 greater than or equal to 50 years) and 55 black men (34 less than 50 years, 21 greater than or equal to 50 years). The results showed men had higher mean renin activities than women, whites had higher activities than blacks and those of under 50 years had higher activities than those of over 50 years. However, the sex and race differences primarily occurred as a consequence of a lack of decline in renin activity with age among white men. The relationship with age as a continuous variable was weak (r = -0.21) and no relationship with age was found in 22 subjects with a least 7 years of data. No significant differences in urinary sodium excretion were observed between the groups. These results suggest that renin activity tends to be lower in older subjects and that differences in renin activity related to sex and race, while statistically significant, may not be physiologically important.

Age Factors↗

PubMed1985

Work-site as locus for hypertension care.

The widespread failure to control high blood pressure (BP) reflects a mismatch between therapist, treatment and patient. Occupationally based programmes which have transformed the method of care, as well as its relationship to the patient, have achieved signal success. Examination of the specific impact of locus of treatment reveals a small but measurable benefit of on-site therapy. Closer inspection reveals that it is the context in which the care is rendered rather than its physical location that is responsible for the satisfactory outcomes achieved. The locus of care, however, cannot be separated from its environment. Occupationally based programmes that are patient-centred, supportive and provide appropriate intervention succeed 'on' or 'off' site. The lesson for conventional sources of care, wherever they exist, is to reorient the process of care and its relation to the patient to over come the disincentives to persistence in successful care.

Female↗

PubMed1984

Isopentenyl Pyrophosphate cis-1,4-Polyisoprenyl Transferase from Guayule (Parthenium argentatum Gray).

Electron micrographs of the mesophyll cells of guayule Parthenium argentatum Gray leaves show deposits of cis-polyisoprene (rubber) in the cytoplasm in the vicinity of mitochondria and chloroplasts and demonstrate that the rubber-synthesizing enzymes are present in guayule leaves. The terminal step in the synthesis of cis-polyisoprene from isopentenyl pyrophosphate (IPP) catalyzed by isopentenyl pyrophosphate cis-1,4-polyisoprenyl transferase has been demonstrated in crude leaf extracts by the enzymic incorporation of [(14)C]isopentenyl pyrophosphate into the polymer and the recovery of [(14)C]levulinic acid following ozonolysis. The rubber transferase activity in the crude extracts of guayule leaves was 5.8 nanomoles isopentenyl pyrophosphate incorporated per milligram protein per hour. This is the first description of the rubber transferase from a nonlaticiferous plant.The specific activity (in units of nanomoles IPP converted per milligram protein per hour) of the partially purified enzyme following chromatography on diethylaminoethyl-cellulose columns was 41.7 units and contained 0.29 units of IPP isomerase activity and 0.08 units of farnesyl pyrophosphate synthetase activity. The rubber transferase requires reduced glutathione and Mg(2+) for maximal activity. There was no incorporation of IPP into cis-1,4-polyisoprene in the absence of rubber particles as primer, and Langmuir isotherm plots showed that the specific activity of the enzyme was proportional to the concentration of the enzyme on the surface of the rubber particles. For a given rubber particle distribution, enzyme activity was proportional to time, IPP concentration, and rubber concentration. The addition of 0.4 millimolar dimethylallyl pyrophosphate to the rubber transferase reaction resulted in a 2-fold increase in the incorporation of IPP into rubber. A comparison was made of the relative activities of rubber transferase in different species of Parthenium, Ficus, and Euphorbia.

Journal Article↗