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Biomedical subjects

R H Lawrence

Publications and source records attributed to R H Lawrence.

14 recordsLinked to original sources
PubMed1997

Subject-caregiver response comparability on global health and functional status measures for African American, Puerto Rican, and Caucasian elders and their primary caregivers.

Ethnic differences in response comparability and bias were evaluated for elderly African American, Puerto Rican, and non-Hispanic Caucasian elderly subjects with some degree of disability and their caregivers. Responses were compared for items assessing basic and instrumental activities of daily living, memory problems, confusion, and global health status. In general, for all ethnic groups, response comparability, based on kappa, was only poor to fair, with the lowest agreement found for items assessing memory problems and confusion. When disagreements occurred, caregivers tended to overestimate impairment relative to the elderly subjects, regardless of ethnicity. However, there were very few significant differences between the response patterns of the caregivers of these different ethnic groups. Thus, although three may be bias in the responses of caregivers relative to elderly persons, in general further bias is not introduced by ethnic differences in comparability of caregiver responses for elders with some degree of disability.

Activities of Daily Living↗
PubMed1996

Disentangling the disablement process.

A model was proposed to assess the premise that functional limitations are an intermediary stage between risk factors (e.g., sex and frequency of walking a mile), pathology/impairments (e.g., musculoskeletal problems), and the onset and course of Instrumental Activities of Daily Living (IADL) disability. Analyses were based on two random subsamples (each with n = 524) of Longitudinal Study of Aging respondents who were nondisabled at baseline (1984) and reinterviewed in 1988 and 1990. The model's central premise was supported in two ways. The main influence of age, frequency of walking, and musculoskeletal problems was on the onset of functional limitations, rather than the onset of IADL disability. And, onset of lower body functional limitations influenced future disability (1990) through its relationship with disability in 1988 and functional limitations in 1990. The results underscore the value of clinical trials which focus on minimizing functional limitations as a strategy for preventing disability.

Activities of Daily Living↗
PubMed1994

Eicosapentaenoic acid modulates neutrophil leukotriene B4 receptor expression in cystic fibrosis.

In patients with cystic fibrosis (CF), high intrapulmonary concentrations of the neutrophil chemotaxin leukotriene B4 (LTB4) are associated with specific reduction of LTB4-induced chemotaxis of circulating neutrophils. The chemotactic abnormality is partially corrected by dietary supplementation with eicosapentaenoic acid (EPA). LTB4-induced neutrophil chemotaxis is mediated by specific, high-affinity, cell surface LTB4 receptors. The hypotheses that neutrophil LTB4 receptors are down-regulated in CF, and that EPA normalizes receptor expression, were tested by measuring the number (Rmax) and affinity (Kd) of LTB4 receptors on neutrophils from eight CF patients before and after EPA (6 weeks of 2.7 g/day), and from nine normal individuals. High-affinity receptor Rmax was depressed in CF patients (0.6 +/- 0.2 x 10(4)/cell (mean +/- s.d.) versus 1.8 +/- 0.7 x 10(4)/cell in normals), but corrected to normal (2.0 +/- 1.9 x 10(4)/cell) after EPA. High-affinity receptor Kd was depressed in CF patients (0.4 +/- 0.3 nM versus 1.4 +/- 0.5 nM in normals), and also corrected to normal with EPA (1.4 +/- 1.2 nM). Low-affinity receptors were depressed, but did not change significantly with EPA. These results indicate that neutrophil responses in chronic inflammatory lung disease can be influenced directly by LTB4 receptor modulation, and that this effect of EPA predominates over alterations in neutrophil signal transduction in situations of chronic exposure to LTB4.

Adolescent↗
PubMed1993

Pseudomonas aeruginosa bacteraemia. Is pancreatobiliary disease a risk factor?

OBJECTIVE: To review changes in the epidemiology, course, and outcome of bacteraemia caused by Pseudomonas aeruginosa. DESIGN AND SETTING: A retrospective, descriptive study of consecutive cases of P. aeruginosa bacteraemia occurring at a university teaching hospital. PATIENTS AND METHODS: Between January 1980 and December 1989, 164 patients were admitted to Westmead Hospital with P. aeruginosa bacteraemia. Patients in whom there was no clinical evidence of sepsis were excluded from analysis leaving a cohort of 152 patients. Hospital records were reviewed and details of demography, clinical features, therapy, and outcome were recorded. RESULTS: One hundred and fifty-five episodes of P. aeruginosa bacteraemia were recorded at an average rate of 0.39 per 1000 admissions per year. The respiratory and pancreatobiliary tracts were the most common sources of the bacteraemia. Pancreatobiliary disease, independent of an underlying malignancy or immunosuppression, emerged as a previously undescribed risk factor for pseudomonal bacteraemia (incidence of 3.0 episodes per 1000 hospital admissions for patients with this disease). The crude mortality rate was 52%; 35% was attributable to pseudomonal bacteraemia. Factors identified as being independently associated with an increased mortality included hypotension, age of 60 years or older, and the presence of an underlying malignancy. Combination therapy with an antipseudomonal penicillin and an aminoglycoside confers a significant survival advantage independent of underlying neutropenia. CONCLUSIONS: Bacteraemia caused by P. aeruginosa remains an important cause of morbidity and mortality. Pancreatobiliary disease represents a new risk factor for P. aeruginosa bacteraemia, independent of an underlying malignancy or immunosuppression. It may be prudent to consider P. aeruginosa as a cause of sepsis in these circumstances, especially if there has been instrumentation of the biliary tree. Hypotension, age of 60 years or older, and the presence of an underlying malignancy were independently associated with significantly increased mortality. Appropriate antibiotic therapy consisting of an antipseudomonal beta-lactam in addition to an aminoglycoside resulted in a significant decrease in mortality compared with the use of an aminoglycoside alone, not only in the study population as a whole, but also in patients without neutropenia.

Adolescent↗
PubMed1992

Perceived intergenerational solidarity and psychological distress among older Mexican Americans.

A model separating and relating dimensions of intergenerational solidarity with measures of psychological distress was investigated for older Mexican Americans. Solidarity consisted of measures of similarity, affection, and association. Measures of psychological distress were somatic/retarded symptoms, depressed affect, and positive affect. To evaluate whether emotional closeness with a particular child modified the linkages, the model was analyzed separately based on whether or not the elderly participant reported that the child included in the intergenerational study was her or his closest child. The findings indicated that the impact of affection and association was a function of the particular dimension of distress and the emotional closeness of the child. Although the proposed model needs expanding, it provides some support for the expectation that family solidarity has important consequences for elderly Mexican Americans.

Aged↗
PubMed1992

Decreased polymorphonuclear leucocyte chemotactic response to leukotriene B4 in cystic fibrosis.

Evidence that leukotriene B4 (LTB4) is a significant inflammatory mediator in chronic pseudomonal respiratory disease was sought in adolescents and young adults with cystic fibrosis. Specific chemotaxis of peripheral blood polymorphonuclear leucocytes (PMN) was used as an indirect measure of remote in vivo exposure to LTB4. PMN from 17 patients showed a significant decrease in chemotaxis to 10(-7)-10(-9) M LTB4, but normal responses to 10(-8) M n-formyl-methionyl-leucyl-phenylalanine and 4 mg/ml casein, when compared with 17 healthy age- and sex-matched controls. This result is consistent with chronic production of LTB4, and specific deactivation of circulating PMN receptors for LTB4 in patients with cystic fibrosis. Pharmacologic inhibition of LTB4 production in vivo may help elucidate its role in the pathogenesis of lung damage in cystic fibrosis.

Adolescent↗
PubMed1990

Appropriateness of composites in structural equation models.

The appropriateness of using composites instead of multiple indicators in a structural model of physical health was evaluated. Liang's (1986) specification of self-reported physical health is a relatively complex multiple indicators model which may not be practical in actual application. To simplify this formulation, a two-stage strategy was used. First, reliability was estimated for each composite to fix the measurement error variance and the regression of the composite on the latent variable. Second, the model was reestimated by constraining these parameters. Regression analyses were undertaken to assess the impact of using composites instead of multiple indicators. Parameter estimates for causal linkages and residual error variances based on multiple indicators approach were closely reproduced by using composites, thus providing justification for the proposed strategy.

Activities of Daily Living↗
PubMed1988

Structural integration of the Affect Balance Scale and the Life Satisfaction Index A: race, sex, and age differences.

In this research we examined race, sex, and age differences in the factorial structure of Liang's (1985) model of subjective well-being that integrates the Affect Balance Scale and the Life Satisfaction Index A. In particular, we viewed the covariance structure of the items as a function of several parameter matrices. We analyzed the factorial invariance by testing hypotheses involving the equivalence constraints of one or more parameter matrices with regard to the following: White and Black subsamples, men and women, and the young-old and the old-old. Data for the research came from the 1974 Harris National Council on Aging Survey, Myths and Reality of Aging in America. Analysis of covariance structures, or LISREL, was used to assess the factorial invariance. Replicated race differences were found in the factorial structure, but sex and age differences were not found. Consistent race differences were found for the second-order factor loadings for negative affect.

Adult↗
PubMed1987

Race differences in factorial structures of two measures of subjective well-being.

This research examines race differences in the factorial structure of two popular measures of psychological well-being: the Philadelphia Geriatric Center (PGC) Morale Scale and the Life Satisfaction Index A (LSIA). In particular, we view the covariance structure of the items of each scale as a function of several parameter matrices. We analyzed the factorial invariance by testing hypotheses involving the equivalence constraints of one or more parameter matrices in the White and the Black samples. Data for the research came from the 1968 National Senior Citizens Survey and the 1974 Harris National Council on Aging Survey, Myths and Reality of Aging in America. Analysis of covariance structures, or LISREL, was used to assess the factorial invariance of both the PGC Morale Scale and the LSIA. Race differences were found in the factorial structure of the PGC Morale Scale, but not in the structure of LSIA. In particular, consistent race differences in measurement error variances were found for two items of the PGC Morale Scale.

Black or African American↗
PubMed1986

Age differences in the structure of the Philadelphia Geriatric Center Morale Scale.

In this research we examined age differences in the factorial structure of the Philadelphia Geriatric Center (PGC) Morale Scale. In particular, we viewed the covariance structure of the PGC Morale Scale items as a function of several parameter matrices. We analyzed the factorial invariance by testing hypotheses involving the equivalence constraints of one or more parameter matrices in the young-old (65-74) and the old-old (75 and over) populations. Data for this research came from the 1968 National Senior Citizens Survey. Analysis of covariance structures, or LISREL, was used to assess the factorial invariance of the PGC Morale Scale. Although there are some statistically significant age differences in the factorial structure, substantively they are less important.

Aged↗
PubMed1978

Effect of isometric hand-grip exercise on the carotid sinus baroreceptor reflex in man.

1. The changes in R--R heart interval that result from step-increase and step-decrease in carotid sinus transmural pressure induced by a variable pressure neck chamber were measured in seven normal men. Observations were made at rest, and during isometric hand-grip exercise at 24%, 44% and 64% of maximal voluntary contraction. 2. The response of heart interval to increase in carotid sinus transmural pressure was progressively and markedly diminished according to the strength of hand-grip. This effect was fully developed from the moment of onset of the exertion. 3. The response of heart interval to decrease in carotid sinus transmural pressure was much less consistently affected by hand-grip exercise.

Adult↗
PubMedDate not supplied

Cellulitis due to Pseudomonas putrefaciens: possible production of exotoxins.

Pseudomonas putrefaciens has been described as a rare cause of both lower-limb cellulitis and septicemic illness with significant morbidity. We report a case of P. putrefaciens infection in a patient with refractory lower-limb cellulitis and ulceration complicated by thrombocytopenia, hypotension, and mental obtundation in the apparent absence of bacteremia. This scenario raises the possibility of significant production of exotoxins by P. putrefaciens in vivo.

Aged↗