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Biomedical subjects

J B Walsh

Publications and source records attributed to J B Walsh.

At least 19 recordsLinked to original sources
PubMed1992

Lattice degeneration of the retina and the pigment dispersion syndrome.

Retinal detachment occurs more frequently in patients with pigment dispersion syndrome. We evaluated the incidence of peripheral retinal abnormalities known to predispose to rhegmatogenous retinal detachment in a consecutive series of 60 patients with pigment dispersion syndrome with or without glaucoma. Lattice degeneration was present in at least one eye of 12 patients (20%). Seven patients had bilateral lesions. Full-thickness retinal breaks were found in seven patients (11.7%) and two patients (3.3%) had asymptomatic rhegmatogenous retinal detachments that required scleral buckle procedures. The incidence of lattice degeneration and full-thickness retinal breaks appears to be increased in this group of patients, and may be responsible for the increased risk of rhegmatogenous detachment.

Adult↗
PubMed1992

Biased gene conversion, copy number, and apparent mutation rate differences within chloroplast and bacterial genomes.

We investigate the possibility that differences between synonymous substitution rates of organelle and bacterial genes differing only in copy number may be due to conversion bias. We find that the rather large observed difference in the synonymous rates between genes in the single copy and inverted-repeat regions of chloroplasts can be accounted for by a very small bias against new mutants. More generally, differences in the within-organelle fixation probability result in different apparent mutation rates as measured by the expected rate of appearance of cells homoplasmic for new mutants. Thus, differences in intracellular population parameters rather than molecular mechanisms can account for some variation in the apparent mutation rates of organelle genes, and possibly in other systems with variable numbers of gene copies. On the other hand, our analysis suggests that conversion bias is not a likely explanation for relatively low mutation rates observed near the replication origin of bacterial chromosomes.

Chloroplasts↗
PubMed1992

Intracellular selection, conversion bias, and the expected substitution rate of organelle genes.

A key step in the substitution of a new organelle mutant throughout a population is the generation of germ-line cells homoplasmic for that mutant. Given that each cell typically contains multiple copies of organelles, each of which in turn contains multiple copies of the organelle genome, processes akin to drift and selection in a population are responsible for producing homoplasmic cells. This paper examines the expected substitution rate of new mutants by obtaining the probability that a new mutant is fixed throughout a cell, allowing for arbitrary rates of genome turnover within an organelle and organelle turnover within the cell, as well as (possibly biased) gene conversion and genetic differences in genome and/or organelle replication rates. Analysis is based on a variation of Moran's model for drift in a haploid population. One interesting result is that if the rate of unbiased conversion is sufficiently strong, it creates enough intracellular drift to overcome even strong differences in the replication rates of wild-type and mutant genomes. Thus, organelles with very high conversion rates are more resistant to intracellular selection based on differences in genome replication and/or degradation rates. It is found that the amount of genetic exchange between organelles within the cell greatly influences the probability of fixation. In the absence of exchange, biased gene conversion and/or differences in genome replication rates do not influence the probability of fixation beyond the initial fixation within a single organelle. With exchange, both these processes influence the probability of fixation throughout the entire cell. Generally speaking, exchange between organelles accentuates the effects of directional intracellular forces.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA Replication↗
PubMed1992

Ocular hazards of nebulized bronchodilators.

Three cases of pupillary dilatation associated with the development of acute glaucoma, precipitated by the use of nebulized bronchodilators are described. We suggest measures to reduce the risk of this complication.

Adult↗
PubMed1992

'Pseudo-Alzheimer's' and primary brain tumour.

Primary brain tumour may present in the elderly purely as a dementing illness before the onset or detection of sensorimotor neurological symptoms or signs. Although neurological examination may indicate no definite signs, close attention to accepted DSM-IIIR and NINCDS-ADRDA diagnostic criteria for primary degenerative dementia and 'probable' Alzheimer's disease respectively will suggest a process other than a degenerative one. This was the case in two patients with primary brain tumour presenting clinically with dementing illness similar to but distinct from Alzheimer's disease.

Aged↗
PubMed1992

Vitamin-D-fortified liquid milk--a highly effective method of vitamin D administration for house-bound and institutionalised elderly.

The aim of the study was to assess the efficacy and acceptability of vitamin-D-fortified liquid milk in the management of hypovitaminosis D in an elderly institutionalised population. The design was a single-blind randomised controlled study. In phase I, patients were encouraged to drink an increased quantity of either fortified or unsupplemented milk for 3 months. In phase II, patients were continued on either fortified or on unsupplemented milk which was given as part of the everyday diet for a further 6 months with no extra encouragement of any patient to take additional amounts. Ninety-eight patients (mean age 84 years) from extended care wards at the Department of Medicine for the Elderly, St. James's Hospital, Dublin, Ireland, participated in the study. Seventy-eight patients completed phase I, and 62 completed phase II. A general biochemical screen and 25-hydroxy vitamin D measurements were performed at entry and repeated 3 and 9 months later. The average milk intake per patient in phase I was 454 ml/day in the unsupplemented group and 359 ml/day in the fortified milk group. In phase II, the average daily milk intake per patient was 235 ml in the unsupplemented milk group and 140 ml in the fortified milk group. Seventy-four patients (94%) of the total who completed phase I had serum vitamin D baseline levels below the normal range. In the fortified milk group, mean vitamin D levels rose from 2.4 to 14.80 ng/ml (p < 0.001) at the end of phase I and remained significantly elevated at 10.2 ng/ml (p < 0.001) at the end of phase II.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Role of diabetes mellitus on the natural history of central retinal vein occlusion.

In order to elucidate the role of diabetes mellitus on the natural history of central retinal vein occlusion, we compared two groups of central retinal vein occlusion, one with diabetes mellitus (32 patients) and one without diabetes mellitus (113 patients). The two groups were quite similar with respect to age, sex, systemic hypertension and glaucoma. No fellow eye had proliferative diabetic retinopathy. The diabetic group had angiographically a more ischemic type of central retinal vein occlusion (72%) than the nondiabetic group (39%; p less than 0.002). Diabetics with central retinal vein occlusion should be closely monitored.

Adolescent↗
PubMed1992

Mortality and morbidity in patients with central retinal vein occlusion.

We investigated the risk of mortality and morbidity in 78 patients with central retinal vein occlusion (CRVO) followed for more than 2 years (mean follow-up 7.2 years). Thirteen subjects died at an average of 7.0 years after CRVO. Five subjects developed myocardial infarction at an average of 2.8 years after CRVO, and 1 developed a cerebrovascular accident 3 years after CRVO. Patients with CRVO do not carry a higher risk of mortality and morbidity than matched controls derived from national surveys.

Adult↗
PubMed1992

Idiopathic preretinal macular gliosis: a retrospective study of 200 patients.

The charts of the last 200 patients with idiopathic preretinal macular gliosis (IPRMG) seen in the Retina Service of Montefiore Medical Center, Albert Einstein College of Medicine, were reviewed. We found that IPRMG is a disease of older people, tends to have a nonprogressive course, and rarely causes severe visual loss. In our series, 91.5% of the patients were older than 50 years of age, 80% of eyes lost less than two lines of vision, and only 4% of eyes had a visual acuity 20/200.

Adult↗
PubMed1991

Prospective hospital study of community acquired lower respiratory tract infection in the elderly.

A prospective study of community acquired lower respiratory tract infection in the elderly was carried out over a 15-month period. During this time 127 consecutive admissions to two acute geriatric medical wards were studied. An aetiology was established in 77 (61%) of cases. Streptococcus pneumoniae was identified in 37% of patients. Haemophilus influenzae in 18% and Branhamella catarrhalis in 10%. Infection with Mycoplasma pneumoniae was found in only one episode and no cases of Legionella pneumophilia were diagnosed. A significant number of patients had multiple bacterial pathogens isolated: 18% of all bacterial pathogens isolated were ampicillin resistant. Fourteen patients died (11%). Lower respiratory tract infection is a frequent cause of hospital admission for those aged over 65 and is often regarded as a preterminal event. Adequately treated however, mortality is no higher than in the general population. Knowledge of the likely pathogens allows early and appropriate antibiotic therapy for these patients whether at home or on admission to hospital.

Aged↗
PubMed1991

Caring for dementia sufferers in the community: the caregivers problems.

Twenty-four carers of dementia sufferers were screened for psychological well being and compared with 19 carers of non-demented elderly. Carers of demented relatives showed significantly raised levels of stress on the Relatives' Stress Scale (RSS), and also increased psychiatric morbidity on the 30 item General Health Questionnaire (GHQ-30), when compared with the carers on non-demented relatives. Scores in the behaviour and mood disturbance scale (BMD) were significantly raised in the dementia group of patients, when compared with the non-demented group. However, high scores on the behaviour and mood disturbance Scale for the dementia sufferer were not correlated with increased stress and psychiatric morbidity scores found in the relatives of the patients with dementia. The implications of these findings are discussed.

Aged↗
PubMed1990

Inconsistencies in standard approximations for selection coefficients at loci affecting a polygenic character.

Inconsistencies exist in the standard expansions used to approximate selection coefficients for alleles at a locus underlying a quantitative character. Allelic (marginal) fitnesses obtained from expansions based on average excesses differ from allelic fitnesses obtained from expansions based on genotypic values. Similarly, W, the mean population fitness based on summing over either allelic or genotypic fitnesses usually differs mean population fitness obtained by averaging over the unrestricted phenotypic distribution. A consistent value of W requires no variation in genotypic values. If, as suggested by Nagylaki (1984), expansions are corrected for the decrease in phenotypic variance resulting from conditioning on the presence of a particular allele or genotype, inconsistencies still exist. Unless integral of W(z)[Vzp"(z) + zp'(z) + p(z)] dz = 0, where p(z) is the phenotypic probability density function, Vz the phenotypic variance, W(z) the fitness of phenotypic value z, the primes denote differentiation with respect to z, allelic fitnesses based on average effects differ from allelic fitnesses based on genotypic values. This condition must also be satisfied in order for either expansion to give a consistent W, as first shown by Nagylaki. For arbitrary W(z), this is satisfied if and only if phenotypes are normally distributed.

Alleles↗
PubMed1990

Elder abuse.

Elder abuse is an under-recognised cause of morbidity in the elderly. The frail elderly with multiple physical and psychiatric problems living with a relative who may also have a physical or psychiatric problem are particularly at risk. Although increased awareness of the problem and a high index of suspicion are necessary factors to diagnose the condition, clinical pointers towards diagnosis are available. Treatment for both victim and "carer" should be on the basis of multi-disciplinary assessment, and may result in admission of the elderly patient to an extended-care facility.

Aged↗
PubMed1990

Optic disc size in central retinal vein occlusion.

Predisposing factors in central retinal vein occlusion (CRVO) have included various systemic disorders and glaucoma. Recent reports have suggested a possible relation between specific anatomic configurations of the optic nerve head and the development of anterior ischemic optic neuropathy. The authors analyzed several optic disc parameters in 57 ocular normotensive patients with unilateral CRVO and in 27 control subjects. There was no significant difference in the horizontal disc diameter and cup-to-disc ratio between eyes with unilateral CRVO, fellow eyes with CRVO, and control eyes. The current data suggest that there is no relation between optic disc size and CRVO.

Fundus Oculi↗
PubMed1990

The effect of mild to moderate dementia on the Geriatric Depression Scale and on the General Health Questionnaire.

The Geriatric Depression Scale (GDS) and two versions of the General Health Questionnaire (GHQ 28 and corrected GHQ 28) were administered to 111 patients admitted to an acute geriatric medical unit. Depression and dementia were diagnosed by semi-structured interview using DSM III criteria. There was no statistically significant difference in the three scales between cognitively normal depressed patients and demented depressed patients. The three scales were sensitive indicators of depressive illness (greater than 90%), but the GHQ 28 and CGHQ 28 needed adjustment of their community-based threshold values.

Aged↗