Biomedical subjects

Robert J Rubin

Publications and source records attributed to Robert J Rubin.

17 recordsLinked to original sources

PubMed2004

Bone density-related predictors of blood lead level among peri- and postmenopausal women in the United States: The Third National Health and Nutrition Examination Survey, 1988-1994.

Because of the long half-life of lead stored in bone (years), skeletal lead stores may be a source of endogenous lead exposure during periods of increased bone demineralization, such as menopause. To test the hypothesis that postmenopausal bone resorption increases blood lead levels, the authors examined cross-sectional associations of bone density-related factors with blood lead levels among women aged 40-59 years from the Third National Health and Nutrition Examination Survey (1988-1994). Factors related to bone turnover were significant predictors of blood lead level. Bone mineral density was significantly inversely related to blood lead levels in log-linear multivariate models that adjusted for age, race/ethnicity, smoking, education, household income, alcohol use, and residence (urban/rural). With menopausal status added to the model, naturally and surgically menopausal women had adjusted median blood lead levels that were 25% and 30% higher, respectively, than those of premenopausal women (2.0 microg/dl). Current use of hormone replacement therapy was associated with significantly lower adjusted median blood lead levels (1.8 microg/dl) than past use (2.6 microg/dl) and never use (2.2 microg/dl). Lead stored in bone may significantly increase blood lead levels in perimenopausal women because of postmenopausal bone mineral resorption. Attention to factors that prevent bone loss may lessen or prevent this endogenous lead exposure.

Absorptiometry, Photon↗

PubMed2003

Blood lead, blood pressure, and hypertension in perimenopausal and postmenopausal women.

CONTEXT: Lead exposures have been shown to be associated with increased blood pressure and risk of hypertension in older men. In perimenopausal women, skeletal lead stores are an important source of endogenous lead exposure due to increased bone demineralization. OBJECTIVE: To examine the relationship of blood lead level with blood pressure and hypertension prevalence in a population-based sample of perimenopausal and postmenopausal women in the United States. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional sample of 2165 women aged 40 to 59 years, who participated in a household interview and physical examination, from the Third National Health and Nutrition Examination Survey conducted from 1988 to 1994. MAIN OUTCOME MEASURES: Associations of blood lead with blood pressure and hypertension, with age, race and ethnicity, cigarette smoking status, body mass index, alcohol use, and kidney function as covariates. RESULTS: A change in blood lead levels from the lowest (quartile 1: range, 0.5-1.6 micro g/dL) to the highest (quartile 4: range, 4.0-31.1 microg/dL) was associated with small statistically significant adjusted changes in systolic and diastolic blood pressures. Women in quartile 4 had increased risks of diastolic (>90 mm Hg) hypertension (adjusted odds ratio [OR], 3.4; 95% confidence interval [CI], 1.3-8.7), as well as moderately increased risks for general hypertension (adjusted OR, 1.4; 95% CI, 0.92-2.0) and systolic (>140 mm Hg) hypertension (adjusted OR, 1.5; 95% CI, 0.72-3.2). This association was strongest in postmenopausal women, in whom adjusted ORs for diastolic hypertension increased with increasing quartile of blood lead level compared with quartile 1 (adjusted OR, 4.6; 95% CI, 1.1-19.2 for quartile 2; adjusted OR, 5.9; 95% CI, 1.5-23.1 for quartile 3; adjusted OR, 8.1; 95% CI, 2.6-24.7 for quartile 4). CONCLUSIONS: At levels well below the current US occupational exposure limit guidelines (40 microg/dL), blood lead level is positively associated with both systolic and diastolic blood pressure and risks of both systolic and diastolic hypertension among women aged 40 to 59 years. The relationship between blood lead level and systolic and diastolic hypertension is most pronounced in postmenopausal women. These results provide support for continued efforts to reduce lead levels in the general population, especially women.

Adult↗

PubMed2003

Evaluation of the ESRD managed care demonstration operations.

Individuals with end stage renal disease (ESRD), most of whom are insured by Medicare, are generally prohibited from enrolling in Medicare managed care plans (MCPs). CMS offered ESRD patients the opportunity to participate in an ESRD managed care demonstration mandated by Congress. The demonstration tested whether managed care systems would be of interest to ESRD patients and whether these approaches would be operationally feasible and efficient for treating ESRD patients. This article examines the structure, implementation, and operational outcomes of the three demonstration sites, focusing on: the structure of these managed care programs for ESRD patients, requirements needed to attract and enroll patients, and the challenges of introducing managed care programs in the ESRD arena.

California↗

PubMed2003

Patient selection in the ESRD managed care demonstration.

The Centers for Medicare & Medicaid Service's (CMS') end stage renal disease (ESRD) managed care demonstration offered an opportunity to assess patient selection among a chronically ill and inherently costly population. Patient selection refers to the phenomenon whereby those Medicare beneficiaries who choose to enroll or stay in health maintenance organizations (HMOs) are, on average, younger, healthier, and less costly to treat than beneficiaries who remain in the traditional Medicare fee-for-service (FFS) sector. The results presented in this article show that enrollees into the demonstration were generally younger and healthier than a representative group of comparison patients from the same geographic areas.

Adult↗

PubMed2003

Quality of life and patient satisfaction: ESRD managed care demonstration.

To study the effects of managed care on dialysis patients, we compared the quality of life and patient satisfaction of patients in a managed care demonstration with three comparison samples: fee-for-service (FFS) patients, managed care patients outside the demonstration, and patients in a separate national study. Managed care patients were less satisfied than FFS patients about access to health care providers, but more satisfied with the financial benefits (copayment coverage, prescription drugs, and nutritional supplements) provided under the demonstration managed care plan (MCP). After 1 year in the demonstration, patients exhibited statistically and clinically significant increases in quality of life scores.

California↗

PubMed2003

ESRD managed care demonstration: financial implications.

In 1996, CMS launched the end stage renal disease (ESRD) managed care demonstration to study the experience of offering managed care to ESRD patients. This article analyzes the financial impact of the demonstration, which sought to assess its economic impact on the Federal Government, the sites, and the ESRD Medicare beneficiaries. Medicare's costs for demonstration enrollees were greater than they would have been if these enrollees had remained in the fee-for-service (FFS) system. This loss was driven by the lower than average predicted Medicare spending given the demonstration patients' conditions. The sites experienced losses or only modest gains, primarily because they provided a larger benefit package than traditional Medicare coverage, including no patient obligations and other benefits, especially prescription drugs. Patient financial benefits were approximately $9,000 annually.

Adolescent↗

PubMed2002

Fluctuations and randomness of movement of the bead powered by a single kinesin molecule in a force-clamped motility assay: Monte Carlo simulations.

The motility assay of K. Visscher, M. J. Schnitzer, and S. M. Block (Nature, 400:184-189, 1999) in which the movement of a bead powered by a single kinesin motor can be measured is a very useful tool in characterizing the force-dependent steps of the mechanochemical cycle of kinesin motors, because in this assay the external force applied to the bead can be controlled (clamped) arbitrarily. However, because the bead is elastically attached to the motor and the response of the clamp is not fast enough to compensate the Brownian motion of the bead, interpretation or analysis of the data obtained from the assay is not trivial. In a recent paper (Y. Chen and B. Yan, Biophys. Chem. 91:79-91, 2001), we showed how to evaluate the mean velocity of the bead and the motor in the motility assay for a given mechanochemical cycle. In this paper we extend the study to the evaluation of the fluctuation or the randomness of the velocity using a Monte Carlo simulation method. Similar to the mean, we found that the randomness of the velocity of the motor is also influenced by the parameters that affect the dynamic behavior of the bead, such as the viscosity of the medium, the size of the bead, the stiffness of the elastic element connecting the bead and the motor, etc. The method presented in this paper should be useful in modeling the kinetic mechanism of any processive motor (such as conventional kinesin and myosin V) based on measured force-clamp motility data.

Binding Sites↗

PubMedDate not supplied

The burden of Staphylococcus aureus infections on hospitals in the United States: an analysis of the 2000 and 2001 Nationwide Inpatient Sample Database.

BACKGROUND: Previous studies have investigated the impact of Staphylococcus aureus infections on individual hospitals, but to date, no study using nationally representative data has estimated this burden. METHODS: This is a retrospective analysis of the 2000 and 2001 editions of the Agency for Healthcare Research and Quality's Nationwide Inpatient Sample database, which represents a stratified 20% sample of hospitals in the United States. All inpatient discharge data from 994 hospitals in 28 states during 2000 and from 986 hospitals in 33 states during 2001, representing approximately 14 million inpatient stays, were analyzed to determine the association of S aureus infections with length of stay, total charges, and in-hospital mortality. RESULTS: Staphylococcus aureus infection was reported as a discharge diagnosis for 0.8% of all hospital inpatients, or 292 045 stays per year. Inpatients with S aureus infection had, on average, 3 times the length of hospital stay (14.3 vs 4.5 days; P<.001), 3 times the total charges (48,824 US dollars vs 14,141 US dollars; P<.001), and 5 times the risk of in-hospital death (11.2% vs 2.3%; P<.001) than inpatients without this infection. Even when controlling for hospital fixed effects and for patient differences in diagnosis-related groups, age, sex, race, and comorbidities, the differences in mean length of stay, total charges, and mortality were significantly higher for hospitalizations associated with S aureus. CONCLUSIONS: Staphylococcus aureus infections represent a considerable burden to US hospitals, particularly among high-risk patient populations. The potential benefits to hospitals in terms of reduced use of resources and costs as well as improved outcomes from preventing S aureus infections are significant.

Age Factors↗

PubMedDate not supplied