Biomedical subjects

L L White

Publications and source records attributed to L L White.

14 recordsLinked to original sources

PubMed2000

A systematic review of troponin T and I values as a prognostic tool for patients with chest pain.

OBJECTIVE: The accuracy of the troponin T and I test as a prognostic tool for patients with chest pain varies considerably depending on the patient population, the cutoff for an abnormal test result, and other factors. The goal of our systematic review was to synthesize the best available evidence on this topic. SEARCH STRATEGY: We searched the MEDLINE database, bibliographies of identified articles, and articles identified from a previous meta-analysis of diagnosis. SELECTION CRITERIA: We included cohort studies that had at least 80% follow-up and reported useful data. DATA COLLECTION AND ANALYSIS: Data from each study were abstracted by 2 investigators. We calculated sensitivity and specificity for the prediction of death, fatal or nonfatal myocardial infarction (MI), or any cardiac event for each combination of patient population, troponin test, interval from admission to blood draw, and cutoff for an abnormal test result. MAIN RESULTS: For patients with chest pain and a normal electrocardiogram, the peak troponin I level drawn 6 or more hours after the onset of chest pain is useful for identifying patients at low risk of death or nonfatal MI at 30 days (negative likelihood ratio=0.07; probability of outcome=0.3% with a negative test, given a pretest probability of 4.4%). For patients with unstable angina, the sensitivity of troponin I for the identification of patients who die or have a nonfatal MI in the next 30 days is only 59%, and the specificity is only 79%. The sensitivity and specificity varied widely for patients with unstable angina or non-Q-wave MI depending on the inclusion criteria, cutoff used, timing of the blood draw, duration of follow-up, aim other factors. CONCLUSIONS: If the peak troponin T or I level measured at least 6 hours after the onset of chest pain symptoms is in the normal range in a patient with a normal electrocardiogram, it is very unlikely that the patient will die or have a nonfatal MI in the next 30 days (< or =1%). The initial troponin value is not as helpful as the peak value at least 6 hours after the onset of chest pain. An abnormal troponin test result for patients with unstable angina or non-Q-wave MI identifies a subset at greater risk of death.

Angina, Unstable↗

PubMed1997

Rationale, design and methodology for the Navajo Health and Nutrition Survey.

As recently as 1990, there was no reservation-wide, population-based health status information about Navajo Indians. To remedy this shortcoming, the Navajo Health and Nutrition Survey was conducted from 1991 to 1992 to assess the health and nutritional status of Navajo Reservation residents using a population-based sample. Using a three-stage design, a representative sample of reservation households was selected for inclusion. All members of selected households 12 y of age and older were invited to participate. A total of 985 people in 459 households participated in the study. Survey protocols were modeled on those of previous national surveys and included a standard blood chemistry profile, complete blood count, oral glucose tolerance test, blood pressure, anthropometric measurements, a single 24-h dietary recall and a questionnaire on health behaviors. The findings from this survey, reported in the accompanying papers, inform efforts to prevent and control chronic disease among the Navajo. Lessons learned from this survey may be of interest to those conducting similar surveys in other American Indian and Alaska Native populations.

Adolescent↗

PubMed1997

Intake of nutrients and food sources of nutrients among the Navajo: findings from the Navajo Health and Nutrition Survey.

Diet has been implicated in the etiology of chronic diseases in many populations, including the Navajo and other American Indian tribes. This report describes the current nutrient intake of the Navajo and identifies the primary food sources of key nutrients. In the Navajo Health and Nutrition Survey, interviewers obtained single 24-h diet recalls from 946 nonpregnant participants age 12-91 between October 1991 and December 1992. Among various sex and age groups, total fat contributed 33-35% of energy and saturated fat contributed 10-11% of energy in the diets. Median fiber intake was 11-14 g/d. Median intakes of vitamin A, vitamin E, vitamin B-6, folate, calcium and magnesium were below sex- and age-specific recommended dietary allowances (RDA) for men and women of all age groups. Intake of vitamin C was below the RDA for men and women age 20 and older. Median iron intake was below the RDA for women under age 60. Fruits and vegetables were each consumed less than once per day per person, as were dairy products. Fry bread and Navajo tortillas, home-fried potatoes, mutton, bacon and sausage, soft drinks, coffee and tea provided 41% of the energy and 15-46% of the macronutrients consumed. Recommendations to increase the intake of essential micronutrients in the Navajo diet are presented.

Adolescent↗

PubMed1997

Weight, body image, and weight control practices of Navajo Indians: findings from the Navajo Health and Nutrition Survey.

Historically, the Navajo exhibited a low prevalence of overweight, but a number of small studies over the past few decades indicate that the prevalence is increasing. In the population-based Navajo Health and Nutrition Survey conducted in 1991-92, overweight was defined as a body mass index (BMI, kg/m2) at or above the 85th percentile (BMI > 27.8 for men, > 27.3 for women) of the Second National Health and Nutrition Examination Survey. One third of men age 20 and 39 and one half of men age 40 and 59, but fewer than 10% of men age 60 and older were overweight. Two thirds or more of women in all age groups were overweight. Nineteen percent of the participants underestimated their weight status (underweight, appropriate, overweight) relative to their BMI category and 17% overestimated their weight status. Women overestimated their weight status more often than men (P < 0.05), and participants age 20-39 overestimated their weight status more often than older participants (P < 0.001). Men and women age 60 and older preferred heavier body shape models as ideals of health more often than younger participants (P < 0.001). Nearly half of the participants, regardless of their weight status, reported that they were trying to lose weight; most reported using diet and exercise. Because overweight is an important risk factor for many chronic diseases, including diabetes mellitus, cardiovascular disease and cancer, primary prevention of overweight and weight management for adults are recommended to prevent an increase in the burden of chronic disease among the Navajo.

Adult↗

PubMed1997

Risk factors for coronary heart disease among Navajo Indians: findings from the Navajo Health and Nutrition Survey.

Coronary heart disease was uncommon among the Navajo in the past, but appears to have increased substantially over the last few decades. The 1991-1992 Navajo Health and Nutrition Survey, which included interviews and examinations of 303 men and 485 women between the ages of 20 and 91 y, is the first population-based examination of coronary heart disease risk factors in this tribe. Coronary heart disease risk characteristics were common, particularly overweight (men, 35%; women, 62%), hypertension (men, 23%; women, 14%) and diabetes mellitus (men, 17%; women, 25%). Among 20- to 39-y-olds, a large proportion of men reported that they currently smoked cigarettes (23%); use of chewing tobacco or snuff was also prevalent among these 20- to 39-y-old men (37%) and women (31%). Although serum concentrations of total cholesterol were fairly comparable to those seen in the general U.S. population, fasting serum triglyceride concentrations were high (median: men, 132 mg/dL; women, 137 mg/dL), and concentrations of HDL cholesterol were low, particularly among women (median: men, 42 mg/dL; women, 44 mg/dL). Body mass index was associated with levels of most risk factors, and, independently of the level of overweight, a truncal pattern of body fat was related to adverse lipid levels among men. A large proportion of men (20%) and women (30%) reported not having participated in physical activity during the preceding month. Lessons learned from past intervention activities among the Navajo, particularly those for diabetes, may be useful in managing these risk factors to reduce the future burden of coronary heart disease.

Adolescent↗

PubMed1997

Diabetes mellitus among Navajo Indians: findings from the Navajo Health and Nutrition Survey.

Noninsulin-dependent diabetes mellitus is a major health problem among most American Indian tribes. This is the first population-based reservation-wide study of the Navajo that has used oral glucose tolerance testing to determine diabetes status. Employing WHO criteria, we found an age-standardized prevalence of diabetes mellitus (DM) of 22.9% among persons aged 20 y and older. This prevalence is 40% higher than any previous age-standardized estimate for the Navajo and four times higher than the age-standardized U.S. estimate. More than 40% of Navajo aged 45 y and older had DM. About one third of those with DM were unaware of it, with men more likely to be unaware than women. Among persons with a medical history of DM, almost 40% had fasting plasma glucose values > or = 200 mg/dL. Persons with DM were heavier, more sedentary and more likely to have a family history of DM than were persons without DM. Persons with DM had more hypertension, lower HDL levels and higher triglyceride levels than their counterparts without DM. Insulin usage was infrequent among persons with a history of DM, and about one third of women with such a history used no medical therapy to control their diabetes. Although important measures to combat diabetes have already been undertaken by the Navajo, additional efforts are required to slow the progression of this disease and prevent its sequelae.

Adult↗

PubMed1997

Liposomes containing alpha-tocopherol and ascorbate are protected from an external oxidant stress.

The interaction between alpha-tocopherol and ascorbate in protecting membrane lipids from peroxidation was studied in unilamellar liposomes in which alpha-tocopherol was incorporated into the liposomal membrane, and ascorbate was trapped within the vesicles. Extravesicular ferricyanide was reduced by ascorbate-derived electrons, and this was enhanced by the presence of alpha-tocopherol in the lipid bilayer. When a water-soluble free radical initiator was added to the outside of liposomes, intravesicular ascorbate prevented oxidation of alpha-tocopherol, and this effect was associated with complete protection against peroxidation of membrane lipids. These results suggest that ascorbate-dependent recycling of alpha-tocopherol can protect biological membranes from peroxidation by oxidants originating across the membrane bilayer from ascorbate.

Antioxidants↗

PubMed1996

Antimicrobials prescribed for otitis media in a pediatric Medicaid population.

Antimicrobial prescribing patterns for Tennessee Medicaid children having their first case of otitis media (OM) in at least nine months were studied. Tennessee Medicaid claims data for patients under 11 years whose first documented OM diagnosis in 1993 occurred in the fourth quarter and who had had an antimicrobial claim filed within two days of diagnosis were studied to determine antimicrobial prescribing patterns. Of 7357 children meeting the study criteria, 70% were less than three years of age, 65% were Caucasian, and 60% had a rural address. Twenty antimicrobials were prescribed. Amoxicillin was prescribed most frequently (53% of the time), followed by cefaclor; all first-line therapies (amoxicillin, ampicillin, erythromycin-sulfisoxazole, and trimethoprim-sulfamethoxazole) accounted for 64% of the prescriptions, but only one fourth of the costs. The highest use of first-line therapy was associated with children under three years of age; children without prior antimicrobial therapy, recent upper respiratory infection (URI), or recent sinusitis; children seen by emergency department physicians; and children seen by urban physicians. Tennessee Medicaid would have saved +68,250 if first-line therapy had been used for all children having their first occurrence of OM in the fourth quarter alone. The savings to the state were estimated at +300,000 or more in 1993 had first-line therapy been used for most first occurrences of OM in all four quarters plus even a small percentage of the estimated 30,000 remaining repeat OM cases. Amoxicillin was prescribed 53% of the time, and all first-line therapies 64% of the time, for children with their first case of OM in at least nine months. In children without recent antimicrobial therapy, URI, or sinusitis, first-line therapy was still used only 72% of the time.

Age Distribution↗

PubMed1996

Blood pressure and body measurements among Navajo adolescents.

WE ASSESSED THE PREVALENCE of obesity, high normal blood pressure (BP), and the relationship between BP and anthropometric measurements in a sample of Navajo adolescents. The prevalence of obesity in boys and girls was 3 times that expected in U.S. white adolescents of the same age (17.1% for boys, 15.9% for girls) using body mass index as a criterion. The prevalence of high normal BP (between the 90th and 95th percentiles) was nearly twice that expected by definition (8.7% for boys and 9.1% for girls). Although systolic blood pressure (SBP) and diastolic blood pressure (DBP) increased significantly with age for boys and not for girls, SBP and DBP increased significantly with increasing body mass for both boys and girls. Given the high prevalence of obesity and the observed association with BP, primary prevention of hypertension among the Navajo should emphasize maintaining a healthy body weight at early ages.

Adolescent↗

PubMed1994

Weight perceptions and weight control practices in American Indian and Alaska Native adolescents. A national survey.

OBJECTIVE: To assess weight perceptions and weight control practices among American Indian-Alaska Native adolescents. DESIGN: Survey. SETTING: Nonurban schools from eight Indian Health Service areas. PARTICIPANTS: A total of 13,454 seventh- through 12th-grade American Indian-Alaska Native youths. MAIN OUTCOME MEASURES: A revised version of the Adolescent Health Survey, a comprehensive, anonymous self-report questionnaire with eating- and body image-related questions. RESULTS: Forty-one percent of the adolescent girls reported feeling overweight, 50% were dissatisfied with their weight, and 44% worried about being overweight. Almost half (48%) had been on a weight-loss diet in the past year, with 27% reporting that they had self-induced vomiting at some time to try to lose weight. Eleven percent reported using diet pills. Girls who reported feeling overweight were more likely to engage in unhealthy weight control practices than were those who felt they were of normal weight or underweight. A larger proportion of boys were satisfied with their weight (68%), with 22% worrying about being overweight. However, compared with rural Minnesota youth, both American Indian girls and boys had greater dissatisfaction with body weight. CONCLUSIONS: Our study shows that American Indian youth, particularly girls, are dissatisfied with their weight and are worried about being overweight, and that unhealthy weight control practices are common. More attention needs to be placed on developing culturally appropriate weight management programs for Indian youths.

Adolescent↗

PubMed1990

D variant of encephalomyocarditis virus (EMCV-D)-induced diabetes following natural killer cell depletion in diabetes-resistant male C57BL/6J mice.

The involvement of natural killer (NK) cells in the development of diabetes in the normally resistant 9-10 week old C57BL/6J male mice by the D variant of encephalomyocarditis virus (EMCV-D) was examined. Inoculation of purified EMCV-D induced maximum NK cell activity in splenic cell populations on day 4 post-inoculation as determined by lysis of YAC-1 target cells in a standard 51chromium release microcytotoxicity assay. Selective depletion of NK cells by the administration of rabbit anti-asialo GM1 sera prior to challenging the C57BL/6J mice with EMCV-D, resulted in diminished splenic NK cell activity, increased EMCV-D viral titers in the pancreas, spleen, heart and brain, and the induction of diabetes in 60-80% of the mice. The data suggest that NK cells play a role in host protection against the diabetogenic EMCV-D.

Animals↗

PubMed1990

Evidence for a secular change in obesity, height, and weight among Navajo Indian schoolchildren.

A survey measuring heights and weights of 1969 schoolchildren residing on the Navajo Indian Reservation was conducted in 1989. The findings were compared with National Center for Health Statistics (NCHS) reference data and with surveys of Navajo children from 1955, 1968, and 1981. Approximately twice as many children exceeded the 95th percentile of weight-for-age (11.2% of girls, 12.5% of boys) than would be expected for the NCHS reference population. The mean weight-for-height z scores exceeded those for the NCHS reference population for all ages in both sexes. Compared with data from 1955, mean heights increased 6.1% among boys and 4.4% among girls whereas mean weights increased 28.8% among boys and 18.7% among girls across all age groups. The data suggest that there has been a secular change in height, weight, and obesity in Navajo Indian children over the past 35 y.

Adolescent↗

PubMed1987

In vitro sensitization using thymocyte conditioned medium prepared from fetal calf, horse and rabbit sera.

Thymocyte conditioned medium (TCM) was prepared using 2 lots of fetal calf, and 1 lot each of horse and rabbit sera. The 4 TCM and the respective sera alone were compared in their ability to support primary in vitro sensitization to sheep red blood cells (SRBC) as assayed by direct plaque formation. As would be expected, only the fetal calf sera (FCS) supported the primary in vitro sensitization to SRBC, while the use of the TCM prepared from the FCS resulted in a doubling of direct plaque formation. TCM prepared from either the rabbit or horse sera did not provide adequate support for this primary antibody response to SRBC. These data indicate that only sera able to support primary in vitro sensitization is useful for the preparation of active TCM ultimately used in B cell sensitization for hybridoma formation.

Animals↗

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Physician board members.

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Delivery of Health Care↗