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Biomedical subjects

R M Andrews

Publications and source records attributed to R M Andrews.

36 records · Page 2Linked to original sources
PubMed1999

Histochemical localisation of mitochondrial enzyme activity in human optic nerve and retina.

AIMS: To demonstrate the quantitative distribution of mitochondrial enzymes within the human optic nerve and retina in relation to the pathogenesis of ophthalmic disease. METHODS: Enucleations were performed at the time of multiple organ donation and the optic nerve and peripapillary retina immediately excised en bloc and frozen. Reactivities of the mitochondrial enzymes cytochrome c oxidase and succinate dehydrogenase were demonstrated in serial cryostat sections using specific histochemical assays. RESULTS: In the optic nerve the unmyelinated prelaminar and laminar regions were rich in both cytochrome c oxidase and succinate dehydrogenase. Myelination of fibres as they exited the lamina cribrosa was associated with an abrupt reduction in enzyme activity. Within the retina, high levels of enzyme activity were found localised within the retinal ganglion cells and nerve fibre layer, the outer plexiform layer, inner segments of photoreceptors, and the retinal pigment epithelium. CONCLUSIONS: Mitochondrial enzyme activity is preserved in human optic nerve and retina retrieved at the time of multiple organ donation. The distribution of enzyme activity within the eye has implications for the understanding of the pattern of ophthalmic involvement seen in mitochondrial diseases and the site of ganglion cell dysfunction in those patients with optic nerve involvement.

DNA, Mitochondrial↗
PubMed1999

Mitochondrial DNA analysis: polymorphisms and pathogenicity.

The investigation of mtDNA disease can be relatively straightforward if a person has a recognisable phenotype and if it is possible to identify a known pathogenic mtDNA mutation. The difficulties arise when no known mtDNA defect can be found, or when the clinical abnormalities are complex and not easily matched to those of the more common mitochondrial disorders. We will describe here the difficulties that can be encountered during the identification of pathogenic mtDNA mutations and the approaches that can be used to confirm, or eliminate, a likely pathogenic role, in either single gene diseases or in multifactorial disorders.

Animals↗
PubMed1998

Vaccinating children with a history of serious reactions after vaccination or of egg allergy.

OBJECTIVE: To describe the results of vaccinating children with a history of serious adverse reactions after vaccination or of egg allergy at a special clinic established for that purpose. DESIGN: Retrospective case series. PATIENTS: Children who attended the clinic between 1 August 1994 and 31 July 1996 after being referred by vaccine providers. SETTING: A clinic conducted in the Emergency Department of The Canberra Hospital, Australian Capital Territory. MAIN OUTCOME MEASURES: Reasons for referral; vaccinations given; and subsequent adverse vaccination events. RESULTS: 91 children received 155 vaccinations at the clinic, and only one serious event--a hypotonic/hyporesponsive episode (HHE) after diphtheria-tetanus-whole-cell pertussis (DTPw), oral polio and Haemophilus influenzae type b vaccination--was subsequently reported; this child recovered spontaneously. Fifty-three children referred because of a previous serious adverse vaccination event were revaccinated at the clinic with whole-cell pertussis vaccine (47), combined diphtheria and tetanus vaccine (4), tetanus toxoid (1), and typhoid vaccine (1). Three children (referred because of previous meningitis, subdural haemorrhage or parental suspicion of allergy to DTPw) received their first dose of pertussis vaccine at the clinic. The remaining 35 children had a history of egg allergy and were given measles-mumps-rubella vaccine. CONCLUSIONS: We successfully vaccinated children with histories of serious reactions to vaccination, including HHEs, convulsions, apnoea, high temperatures and persistent screaming, as well as those with egg allergy. We believe special clinics can improve vaccination coverage.

Adolescent↗
PubMed1998

A novel mitochondrial DNA point mutation in the tRNA(Ile) gene: studies in a patient presenting with chronic progressive external ophthalmoplegia and multiple sclerosis.

We report a new mutation, a G to A transition at nucleotide position 4298 within the mitochondrial tRNA(Ile) gene in a patient with chronic progressive external ophthalmoplegia and multiple sclerosis. The mutation, which alters an evolutionary conserved nucleotide within the anticodon stem, was heteroplasmic in skeletal muscle but was not present in the patient's blood. Single fibre PCR analysis revealed significantly higher levels of the G4298A mutation in cytochrome c oxidase (COX) negative fibres than in COX-positive fibres. This mutation represents the seventh pathogenic nucleotide substitution to be found in this gene and as such confirms the tRNA(Ile) gene as a susceptible "hot spot" for mitochondrial DNA point mutations. Of particular interest is that this patient has the clinical features of both multiple sclerosis and a mitochondrial DNA disorder.

Animals↗
PubMed1997

The effectiveness of topical diclofenac in relieving discomfort following traumatic corneal abrasions.

Diclofenac is a non-steroidal anti-inflammatory drug available in an ophthalmic preparation. We present a prospective randomised double-masked placebo-controlled trial involving 40 patients that assessed the effectiveness of topical diclofenac in relieving pain from traumatic corneal abrasions. Statistical analysis of visual analogue and categorical pain scores revealed a significant reduction in pain experienced by subjects in the diclofenac group (p < 0.02).

Administration, Topical↗
PubMed1996

Flashes and floaters as predictors of vitreoretinal pathology: is follow-up necessary for posterior vitreous detachment?

PURPOSE: The aim of the study was to determine whether patients presenting with an isolated posterior vitreous detachment require follow-up to identify retinal breaks not apparent at presentation and whether some histories are more predictive of associated serious posterior segment pathology. METHODS: The notes of 295 patients presenting to eye casualty with flashes and/or floaters were reviewed. RESULTS: One hundred and eighty-nine patients (64%) had isolated posterior vitreous detachments, 49 (16.6%) had retinal detachments and 31 (10.5%) had flat retinal tears. Three new breaks (3.3% of all tears found, 1.9% of review appointments) were identified only at follow-up. Although a subjective reduction in vision and a history of less than 6 weeks' duration were strongly predictive of retinal breaks, the large group of patients presenting with floaters alone (124/295, 42%) still harboured a significant proportion (26.7%) of the retinal breaks. CONCLUSIONS: A follow-up visit for patients with an isolated posterior vitreous detachment can be justified to detect the small percentage of asymptomatic retinal breaks. Although a subjective reduction of vision is the symptom most predictive of serious posterior segment pathology, it would be unsafe to identify particular subgroups of patients alone for careful examination.

Emergencies↗
PubMed1991

Lifetime Medicaid service utilization and expenditures for AIDS in New York and California.

Several important gaps exists in information on the health care resources used by people with AIDS, including patterns of outpatient care, differences between populations at risk of the disease, and services paid for by Medicaid. To address the shortage of information in these areas, this study examined average Medicaid expenditures and service use for the time period a person has AIDS. The study population was Medicaid enrollees with AIDS in New York and California who died between October 1985 and September 1986. The study focused on the differences between the two states and between four groups that were proxies for at-risk populations: children, women, drug-using men, and non-drug-using men. Mean lifetime Medicaid expenditures were about $30,000 in New York and $20,000 in California. Inpatient use was higher and outpatient service use was lower in New York than in California after controlling for risk group, diagnosis, and Medicaid eligibility group (a proxy for income level). In California, women had higher expenditures and inpatient use than men. In New York, women and drug-using men had higher expenditures and use of inpatient and outpatient services (except home health care) than the non-drug-using men. Children in New York had higher expenditures and hospital use than adults but similar outpatient service use. Multivariate analyses suggest that differences between risk groups were largely attributable to differences in diagnosis and income level (as measured by Medicaid eligibility group).

Acquired Immunodeficiency Syndrome↗
PubMed1989

The effects of method of presenting health plan information on HMO enrollment by Medicaid beneficiaries.

Marketing strategies are critical for enhancing HMO enrollments among Medicaid beneficiaries when they are provided a choice of health plans. This study examined one component of marketing HMOs--the method of communicating the HMO's attributes. The purpose of the analysis was to determine if characteristics of Medicaid beneficiaries who enroll in HMOs vary by method of communicating information about health plan options. Data were analyzed from the marketing component of California's Prepaid Health Research, Evaluation, and Demonstration (PHRED) project. Five communication methods are examined in the article: brochure, film, county eligibility worker presentation, state representative presentation, and HMO representative presentation. The analysis reveals that each communication method is most effective with a different type of beneficiary. No single consumer characteristic is related to HMO enrollment across all five methods, although lack of a private physician and dissatisfaction with a current provider are associated with choice in four methods. Film is the best method for attracting persons who have an ongoing relationship with a provider.

Adult↗
PubMed1988

Longitudinal patterns of enrollment and expenditures for a Medicaid cohort.

This article is based on 4 years of data for a cohort of Medicaid enrollees in California and Georgia to determine patterns of enrollment and expenditures. The analyses were developed from the statistical system known as Tape-to-Tape, which is based on Medicaid enrollment and claims files from these and other States. The composition of the cohort changed over times as a result of the differential rates of turnover for subgroups of the Medicaid population. Longitudinal expenditure patterns also varied by health service and eligibility group. These Medicaid expenditure patterns differed from those observed previously in Medicare studies, undoubtedly reflecting differences in service coverage under Medicare and Medicaid.

Adult↗
PubMed1988

Acquired immunodeficiency syndrome in California's Medicaid program, 1981-84.

In this article, Medicaid enrollment, use, and expenditures for persons with acquired immunodeficiency syndrome in California from 1981-84 are examined. The data are from Tape-to-Tape, a person-level Medicaid enrollment and claims data base. It was found that expenditures per month of enrollment decreased as length of enrollment during the year increased. Average annual expenditures increased from 1982 to 1983 and then decreased in 1984. This decrease was most pronounced in hospital services with no indication of a substitution of ambulatory services. This decline is primarily a result of a decrease in hospital reimbursement per day as opposed to changes in use, because discharge rates decreased and length of stay increased.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Medicaid expenditures for the disabled under a work incentive program.

Congress enacted Section 1619 of the Social Security Act to enable the disabled receiving Supplemental Security Income (SSI) to obtain jobs and still retain Medicaid health benefits. Congress intended this work incentive to remove the fear of the severely disabled that by obtaining employment they would lose Medicaid benefits. Based on data from 11 States, our analysis found that Medicaid expenditures for Section 1619 enrollees were relatively small and only one-half the average Medicaid expenditure for the disabled. Retaining Medicaid appears to provide a significant work incentive because Medicaid expenditures represent 13 percent of Section 1619 enrollees' earnings.

Data Collection↗
PubMed1975

On nature of Y chromosome fragments induced in Drosophila melanogaster females. III. C(1)RA vs C(1)RM females.

The distribution of breakpoints in the Y chromosome has been determined for samples of Y chromosome fragments recovered from irradiated immature and mature oocytes of females carrying a reversed acrocentric compound X chromosome. Both distributions differ from the distributions determined from Y chromosome fragments recovered from irradiated females carrying a reversed metacentric compound X chromosome. Differential spatial associations of chromosomes in the oocyte nuclei of the two types of females is discussed as a possible cause of the observed differences.

Animals↗
PubMedDate not supplied

Effects of reproductive condition, season, and site on selected temperatures of a viviparous gecko.

The relationship between thermal and reproductive biology is complex and poorly understood. We measured selected body temperatures (T(sel)) for the viviparous gecko Hoplodactylus maculatus. T(sel) was compared among pregnant females, nonpregnant females, and males from two sites: a cool site with biennially reproducing geckos and a warm site with annually reproducing geckos. T(sel) was measured at five times of day during three seasons and compared with microhabitat temperature (T(top)) and field body temperature (T(b)). T(sel) varied with time of day in all comparisons, and the effect of reproductive condition on T(sel) differed between sites and seasons. At both sites, when T(sel) differed between reproductive conditions, pregnant females had higher T(sel) than nonpregnant females and males. Stage of pregnancy affected the degree of elevation of T(sel). Measurements of microhabitat temperature and field T(b) showed that, even in the warmest season, geckos rarely had the opportunity to achieve T(sel) at the cool site but were able to do so at the warm site. The elevation of T(sel) with pregnancy is extreme in this species (up to 8 degrees C), which suggests that an increase in T(b) is critical to successful reproduction. Interactions between the effects of time of day, season, and reproductive condition on T(sel) must be considered in the assessment of thermoregulation in reptiles.

Animals↗