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Biomedical subjects

D E Krueger

Publications and source records attributed to D E Krueger.

At least 19 recordsLinked to original sources
PubMed1993

Adhesion to and invasion of cultured tick (Acarina: Ixodidae) cells by Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) and maintenance of infectivity.

Lyme disease spirochetes, Borrelia burgdorferi, interact with cultured tick cells in ways similar to those reported to occur in the vector Ixodes dammini Spielman, Clifford, Piesman & Corwin. Spirochete adhesion and penetration were examined using a cell line from embryos of Rhipicephalus appendiculatus Neumann that morphologically resembles tick gut cells, RAE25. Cocultivation of B. burgdorferi with these cells permitted prolonged maintenance of infectivity for hamsters. Borrelial adherence to RAE25 cells was time- and density-dependent and increased by 10-15% per h during the first 5.5 h of cocultivation when we used a concentration of 4 x 10(7) spirochetes/ml. After 6 h, > 90% of the cells bound an average of 3-5 spirochetes per cell. Low passage, hamster-infective strains of B. burgdorferi (JMNT and CD16) showed a 2-3-fold higher rate of adhesion to RAE25 cells than the highly passaged, noninfectious strain B31. Inactivation of CD16 or JMNT by heat, starvation, or treatment with puromycin reduced adherence by 40-60%, whereas pretreatment with monoclonal antibodies to the outer surface proteins had no effect. Spirochetes adhered to young I. dammini cell lines to a similar degree as they did to RAE25, whereas lines from the ticks Dermacentor variabilis (Say) (RML15) and Boophilus microplus (Canestrini) (BME26) bound 30-60% fewer spirochetes. Electron microscopy revealed epicellular borreliae associated with coated pits and vesicles before endocytosis, and intracellular spirochetes were surrounded by a host cell-derived membrane.

Animals↗
PubMed1986

Lessons from the Visual Acuity Impairment Survey pilot study.

The Visual Acuity Impairment Survey (VAIS) pilot study was carried out in three large metropolitan areas of the United States to determine whether it would be feasible to conduct a large two-stage survey of the prevalence of visual acuity impairment and its causes. The study was conducted in conjunction with the Health Interview Survey (HIS), performed by the National Center for Health Statistics and the Census Bureau. In the first stage, a simple vision screening test was administered to 1,868 adults in their homes by specially trained Census Bureau interviewers. All those who failed the test, and a sample of those who passed it, were invited to a local clinic for a check on the accuracy of the screen and a detailed eye examination to establish the cause of the impairment. About 89 per cent of the HIS interviewees took the vision screening test in the home and agreed to have the results released, making it possible for the clinic to invite them for an examination. The principal obstacle to the success of the feasibility study was a low rate (less than 50 per cent) of participation in the clinic examination by the target population. Such low participation would leave the survey open to a serious question about its representativeness. The methods and findings of the pilot study are presented because the lessons may be of value to those attempting similar studies in the future. Suggestions are made for methodological modifications that may enhance the chances for success.

Adult↗
PubMed1983

Validity of a survey question as a measure of visual acuity impairment.

Survey questions are frequently used to collect data on the prevalence of vision difficulties. The 1971-1972 Health and Nutrition Examination Survey included both a question about "trouble with your vision even when wearing glasses or contact lenses," and clinical measurement of central distance visual acuity with usual corrective lenses. The question had low sensitivity for impairment of visual acuity, with variation by age and severity of impairment. Sensitivity analyses from other studies are reviewed. (Am J Public Health 1983; 72:93-96.)

Adult↗
PubMed1982

Pseudoexfoliation, intraocular pressure, and senile lens changes in a population-based survey.

The prevalence rate of pseudoexfoliation among persons in the Framingham Eye Study, a population-based survey, increased from 0.6% for ages 52 to 64 years to 2.6% for ages 65 to 74 years to 5.0% for ages 75 to 85 years. Age-adjusted rates showed a statistically significant 2.3 to 1.0 female to male ratio. Pseudoexfoliation was associated with higher intraocular pressure levels and more frequent senile lens changes, but the latter relationship was not statistically significant. The age-specific prevalence rates for the Framingham population are similar to those reported from a mass screening of subjects in Norway, where the condition is thought to be especially common. Some of the previously reported geographic variations in prevalence rates may be due to differences in disease definitions, subject selection, and examination conditions.

Age Factors↗
PubMed1982

Race, iris pigmentation, and intraocular pressure.

The association of intraocular pressure with age, sex, race, iris pigmentation, systemic blood pressure, and family income was evaluated using data from the Health and Nutrition Examination Survey of 1971-1972. In general, mean intraocular pressure was highest for blacks with brown irides and progressively lower for whites with brown irides, whites with neither brown nor blue irides, and whites with blue irides. Multilinear regression analysis showed positive associations of intraocular pressure with systolic blood pressure (p less than 0.0001), age (p less than 0.0001) and amount of iris pigmentation (p less than 0.0001). The association with iris pigmentation held for both a combined race/iris color variable and for iris color among white persons. When race rather than iris pigmentation was used in the regression equation, it was a weaker (p less than 0.03) but still significant risk factor for higher levels of intraocular pressure. Intraocular pressure was negatively associated with family income (p less than 0.004). Despite the significant associations, the proportion of variance in intraocular pressure that was explained by these variables was small (R2 = 0.06).

Adult↗
PubMed1981

Risk factors for fatal heart attack in young women.

Deaths of 338 women at ages 15-44 years attributed to myocardial infarction (MI) on death certificates during an 18-month period in five metropolitan areas were investigated. Evidence of recent MI or evidence that death occurred suddenly was obtained for about half (163) from records of hospitals or medical examiners or from relatives. A case-control study (involving one deceased control, and one hospitalized living control) of risk factors for heart attack was then conducted using interviews with relatives and abstracts of records of hospitals and physicians identified by the relatives as sources of medical care. Information was obtained on history of prior MI, other heart disease, diabetes, thromboembolism, stroke, hypertension, high cholesterol, obesity, oophorectomy, oral contraception and cigarette smoking. Data are presented on the prevalence of these potential risk factors for the case group and each control group, and for subsets of cases consisting of those without prior heart disease, definite MI only, sudden death only, and white women only. Multivariate analyses identify somewhat different sets of risk factors and different levels of risk for the various subgroups. In general, the risk factors are those that have been reported for men, despite the major difference in level of mortality.

Adolescent↗
PubMed1980

Biostatistical analysis of the collaborative glaucoma study. I. Summary report of the risk factors for glaucomatous visual-field defects.

A prospective collaborative study was conducted in five centers during a 13-year period to identify factors that influence the development of visual-field defects (GVFDs) of open angle glaucoma. In 5,000 subjects, GVFDs developed in only 1.7% of eyes. Statistical analysis of 26 factors at first examination identified five that were significantly related to the development of GVFDs--outflow facility, age, applanation pressure, cup-disc ratio, and pressure change after water drinking. Their absolute initial value, and not its change with time, was the important predictor. Multivariate analysis showed their collective predictive power to be undesirably poor, indicating that other factors must play an important role in the development of GVFDs. Mortality-table analysis indicated that during a period of five years, 98.54% of eyes with initial pressure less than 20 mm Hg continued to be free from GVFDs as compared with 93.34% of those with pressure of 20 mm Hg or greater.

Aged↗
PubMed1980

Fatal myocardial infarction and the role of oral contraceptives.

The association between use of oral contraceptives (OC) and death from myocardial infarction (MI) in young women was investigated in a collaborative case-control study conducted in the five largest metropolitan areas in the US. Potential cases were identified from computer tapes of the National Center for Health Statistics. Controls were selected from among women who died from, or were hospitalized for, acute conditions other than heart disease or from accidents, and were matched to cases on age, geographic area, and year of death. Information on cause of death, personal characteristics, OC use, and the presence of conditions predisposing to MI was obtained from interviews with relatives and abstracts of hospital, clinic and physician records. Odds ratios as approximations to relative risks for fatal MI in relation to OC use, and the associated 95% confidence limits, were calculated overall and for subgroups determined by demographic and health history characteristics. Odds ratios in the total study population were not significantly different from one. However, odds ratios significantly different from one were found when attention was restricted to white subjects without contraindications to OC use, andincluding only those cases whose deaths were attributed to MI with the greatest degree of certainty. Smoking was found to be a significant risk factor for fatal MI.

Adolescent↗