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Biomedical subjects

G Riley

Publications and source records attributed to G Riley.

16 recordsLinked to original sources
PubMed1992

Localization of the immunologic activity in the superantigen Staphylococcal enterotoxin B using truncated recombinant fusion proteins.

The exotoxins of certain strains of Staphylococcus aureus strains are able both to stimulate potent proliferation and induce anergy in T lymphocytes expressing the appropriate T cell Ag receptor V beta gene elements. Although T cell activation by the S. aureus enterotoxins requires the presence of accessory cells bearing class II Ag of the MHC, unlike the peptide fragments of nominal Ag, they contact the external surfaces of both the class II MHC and TCR molecules. This paper investigates the immunologically active domains of S. aureus enterotoxin B (SEB) using truncated fragments of rSEB expressed as a fusion protein with protein A. The results of the experiments reported here indicate that the minimal fragment of SEB able to stimulate and induce anergy in hemagglutinin-reactive human T cells expressing V beta 3.1 gene elements is located in the amino-terminal portion of the molecule within residues 1-138. Deletion of the first 30 amino acid residues renders rSEB unable to stimulate T cells expressing V beta 3.1, whereas polyclonal T cells still respond to this molecule. This implies that the stimulation of several TCR-V beta families may be caused by the interaction with different regions of the toxin. The localization of immunologically active sites in the bacterial enterotoxins is needed to investigate both their biology and potential application as immunomodulatory agents.

Antigens, Bacterial↗
PubMed1992

Prostatic abscess: diagnosis and treatment.

We present a series of 25 men with prostatic abscesses studied during an 11-year interval in whom prostatic fluctuation upon digital rectal examination was the most characteristic sign. Transrectal ultrasound was the most reliable method for diagnosis and transurethral drainage under antibiotic coverage was the ideal treatment for this disease.

Abscess↗
PubMed1991

Enrollee health status under Medicare risk contracts: an analysis of mortality rates.

Previous studies comparing the health status of Medicare beneficiaries enrolled under HMO risk contracts to that of Medicare beneficiaries in fee-for-service (FFS) have generally focused on demonstration projects conducted before 1985. This study examines mortality rates in 1987 for approximately 1 million aged Medicare beneficiaries enrolled in 108 HMOs. We estimated adjusted mortality ratios (AMR) for each HMO and across all HMOs, by dividing the actual number of deaths among HMO enrollees by the "expected" number of deaths. The expected number of deaths was based on death rates among local FFS populations, adjusting for age, sex, Medicaid buy-in status, and institutional status. The AMR for all HMO enrollees pooled together was 0.80. For persons newly enrolled in 1987, the AMR was 0.69; in general, AMRs were higher for beneficiaries who had been enrolled for longer periods of time. Among individual HMOs, none exhibited an AMR substantially above 1.00. Regression analysis indicated lower AMRs for staff model HMOs than for either IPA or group models. Low mortality among Medicare HMO enrollees is consistent with favorable selection or with improvements in the health status of enrollees due to better access or quality of care in HMOs. In either case, health status differences between HMO enrollees and FFS beneficiaries have implications for the appropriateness of Medicare's Adjusted Average Per Capita Cost (AAPCC) payment formula for HMOs.

Aged↗
PubMed1989

Biased selection and regression toward the mean in three Medicare HMO demonstrations: a survival analysis of enrollees and disenrollees.

Mortality of aged Medicare enrollees in three demonstration health maintenance organizations (HMOs) was compared with that of three cohorts of local fee-for-service (FFS) beneficiaries as a measure of group differences in health status. Mortality of the HMO and FFS cohorts was tracked via life-table analysis for 6 years after enrollment to measure the persistence of health status differences existing at enrollment. After adjustment for age, sex, Medicaid-eligibility, and institutional status, HMO enrollee mortality was lower than FFS at all three plans in the first year after enrollment. Enrollee mortality at two plans increased to near FFS levels in year 2 and remained relatively stable thereafter. Enrollee mortality at the third plan increased toward FFS levels more gradually and was significantly below FFS levels for the first 5 years of follow-up. Mortality of disenrollees in the 2 years after disenrollment was significantly higher than that of the continuously enrolled in one plan and marginally significantly higher in a second. These findings suggest a pattern of favorable selection at enrollment, followed by different rates of decay in the favorable health status of enrollees. Other health status measures may exhibit different patterns, however. Selection effects may cause payments based on Medicare's AAPCC to be too high or low, in some cases for several years after enrollment.

Aged↗
PubMed1988

The selective dopamine antagonist properties of BRL 34778: a novel substituted benzamide.

BRL 34778, exo-4-amino-5-chloro-2-methoxy-N-[9-(4-fluorophenylmethyl)-9-azabi cyclo(3.3.1) non-3-yl]-benzamide, is a very potent and specific dopamine D2-receptor antagonist. It exhibits a Ki value of 2.14 nM for dopamine D2-receptors but much lower affinity for D1-(Ki 5700 nM) and for many other receptor types. Its action is potent and of long duration in models for antipsychotic activity (4 h ED50s PO are 0.017 mg/kg for antagonism of apomorphine-induced climbing in mice and 0.028 mg/kg for antagonism of amphetamine-induced locomotion in rats). In contrast to its high potency in models for antipsychotic activity, BRL 34778 is much weaker in models for extrapyramidal effects and sedation (4 h ED50s PO are 2.4 mg/kg for inducing catalepsy in rats and 1.14 mg/kg for inhibition of rearing behaviour in rats). These data indicate potent activity of BRL 34778 in models for antipsychotic activity but low activity in models for extrapyramidal effects and sedation.

Adenylyl Cyclase Inhibitors↗
PubMed1987

The use and costs of Medicare services by cause of death.

The high costs and difficult ethical and medical issues often associated with care of the dying are of special interest to the Medicare program, because enrollees in their last year of life account for over one-fourth of total Medicare expenditures. In this study, we look at those costs by cause of death for aged Medicare beneficiaries who died in 1979. We found that expenditures varied markedly by cause of death. Cancer was the most expensive leading cause of death, with per capita expenses of $8,021, compared with $4,012 for heart disease. Because of the greater number of deaths from heart disease, expenses for heart disease decedents accounted for 8.2% of the total Medicare budget in 1979 compared with 7.2% for cancer. These data provide a baseline with which to evaluate the effects of major changes in Medicare on care for the dying.

Aged↗
PubMed1987

Medicare utilization by disabled-worker beneficiaries: a longitudinal analysis.

Medicare eligibility for Social Security disabled-worker beneficiaries begins after 2 years of cash benefit receipt. Extension of the current coverage is often proposed as a way to encourage beneficiaries to return to work. Little is known, however, about the long-run Medicare costs for the disabled and how costs vary by demographic and health characteristics. This article describes Medicare utilization and reimbursement amounts for 1974-81 for a cohort of disabled-worker beneficiaries under age 62 and first entitled to cash benefits in 1972. The data come from a first-time linkage of Disability Insurance program data with data on Medicare utilization. The tables provide a detailed look at several factors that are associated with variation in Medicare costs among beneficiaries and over time.

Persons with Disabilities↗
PubMed1978

A radioimmunoassay for the determination of combined amitriptyline and nortriptyline concentrations in microliter samples of plasma.

A sensitive radioimmunoassay for amitriptyline and nortriptyline in blood has been developed. The antibodies used in the radioimmunoassay were raised in a sheep against a conjugate of nortriptyline and bovine serum albumin. Using tritiated amitriptyline as the label, the assay is capable of detecting concentrations as low as 2.0 ng/ml in a 50 microliter sample of plasma. Cross-reactivity studies have demonstrated the specificity of the radioimmunoassay for both amitriptyline and nortriptyline, and comparison with gas-liquid chromatography assay has indicated the applicability of the assay to a routine situation. The radioimmunoassay has been used to study the plasma drug levels after single oral administration of amitriptyline to four volunteers. A wide variation in maximum drug concentrations, ranging from 18 to 62 ng/ml, was seen, with the time taken to reach the maxima ranging between 1.5 and 3 hours. A second concentration peak was seen in three of the volunteers, at 4 to 5 hours after ingestion of the drug.

Amitriptyline↗