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Biomedical subjects

R S Morrison

Publications and source records attributed to R S Morrison.

108 records · Page 6Linked to original sources
PubMed1982

Developmental expression of rat brain mitogens for cultured astrocytes.

Extracts prepared from prenatal, neonatal, and adult rat brain were examined for the presence of astrocyte mitogens. Extracts were characterized by molecular weight separation on Sephadex G-100. Two major peaks of mitogenic activity, at 80K and 23K daltons, were identified in the adult brain extract. Extract prepared from adult tissue also possessed the lowest specific activity. Extract prepared from neonatal rat brain exhibited four general peaks of activity at approximately 80K, 45K, 23K, and 17K daltons. This extract possessed the highest specific activity. Extract prepared from prenatal rat brain contained six general peaks of activity with unique peaks at 67K, 14K, and less than 10K daltons. In addition, this extract possessed a specific activity intermediate between the adult and postnatal extracts. Differences were also noted among the extracts in their requirement for "permissive" factors found in serum necessary for mitogenic activity. The data have implications for the normal development of astrocytes, as well as for the pathological process of gliosis.

Animals↗
PubMed1981

Growth of purified astrocytes in a chemically defined medium.

Astrocytes purified from primary cultures of neonatal rat cerebrum can now be grown in a synthetic medium supplemented with putrescine, prostaglandin F2 alpha, insulin, fibroblast growth factor, and hydrocortisone. These five supplements have a marked synergistic effect on growth when used in combination but have little effect when used individually. Astrocytes grown in the defined medium exhibit dramatic changes in morphological characteristics in comparison to cells grown in serum-free or serum-supplemented medium. In addition, these cells express the astrocyte-specific marker glial fibrillary acidic protein and are estimated by several criteria to be greater than 95% astrocytes.

Animals↗
PubMed1979

Hyperaccumulation of nickel by Alyssum Linnaeus (Cruciferae).

Herbarium specimens of all except one of the 168 recognized species of Alyssum Linnaeus have been analysed for their nickel content in order to identify hyperaccumulators (greater than 1000 microgram per g dry mass) of nickel. A further 31 hyperaccumulators (all in section Odontarrhena) were discovered in addition to the 14 European species reported earlier. Pot trials on the non-accumulator A. serpyllifolium Desfontaines and the hyperaccumulator A. pintodasilvae Dudley in ed. involving addition of nickel to the medium in which the plants were growing, showed that not all species of of section Odontarrhena were able to act as hyperaccumulators of nickel. Hyperaccumulation occurred almost exclusively in the eastern Mediterranean area and Turkey. There appeared to be a definite correlation between species diversity, proliferation and endemism on the one hand, and extremely high nickel concentrations (greater than 1%) on the other. The data have been used to assess the evidence for promoting section Odontarrhena to generic rank.

Biological Transport↗
PubMed1976

Hormone-fuel concentrations in anephric subjects. Effect of hemodialysis (with special reference to amino acids).

Arterial blood concentrations of insulin, glucagon, and various substrates were determined in six anephric subjects in the postabsorptive state and immediately after hemodialysis. Plasma glucose and serum insulin concentrations were normal, and declined during dialysis. Plasma glucagon was elevated and remained unchanged. There was moderate hypertriglyceridemia before dialysis, but this decreased significantly after administration of heparin just before the start of dialysis, and at the end of dialysis was lowered further into the normal range. Comparison of postabsorptive whole blood concentrations of amino acids with those in normal, healthy adults revealed striking differences. Glutamine, proline, citrulline, glycine and both 1- and 3-methyl-histidines were increased, while serine, glutamate, tyrosine, lysine, and branched-chain amino acids were decreased. The glycine/serine ratio was elevated to 300% and tyrosine/phenylalanine ratio was lowered to 60% of normal. To investigate the potential role of blood cells in amino acid transport, the distribution of individual amino acids in plasma and blood cell compartments was studied. Despite a markedly diminished blood cell mass (mean hematocrit, 20.6 +/- 1.4%), there was no significant decrease in the fraction of most amino acids present in the cell compartment, and this was explained by increases of several amino acids in cellular water. None were decreased. Furthermore, during dialysis, whole blood and plasma amino acids declined by approximately 30% and 40%, respectively, whereas no significant change was observed in the cell compartment. Alanine was the only amino acid whose concentration declined in the cells as well as in plasma. The results indicate (a) significant alterations in the concentrations of hormones and substrates in patients on chronic, intermittent hemodialysis; (b) removal of amino acids during hemodialysis, predominantly from the plasma compartment, with no significant change in cell content; and (c) a redistribution of amino acids in plasma and blood cell compartments with increased gradients of most of the amino acids per unit cell water, by mechanism(s) as yet undetermined.

Adult↗
PubMedDate not supplied

Barriers to completion of health care proxies: an examination of ethnic differences.

BACKGROUND: Advance directives have not been uniformly used by different segments of the US population and studies have consistently shown a lower prevalence of advance directives among African Americans and Hispanics compared with non-Hispanic whites. OBJECTIVE: To examine barriers to completion of health care proxies for different ethnic groups. METHODS: One hundred ninety-seven subjects aged 65 years or older self-identified as African American (n = 65), Hispanic (n = 65), or non-Hispanic white (n = 67) attending a geriatrics and internal medicine outpatient clinic of a large New York City teaching hospital were administered a questionnaire. Questionnaires were developed to examine potential barriers to completion of health care proxies. Barriers were drawn from the literature and from focus groups. RESULTS: Significant predictors of proxy completion using logistic regression analysis included knowledge of health care proxies, availability of a health care agent, exposure to mechanical ventilation, age, and self-reported health status as fair to poor. Subjects who believed that a health care agent was irrelevant in the setting of involved family were significantly less likely to have completed a health care proxy. Although there were significant differences in the baseline completion rates of health care proxies for the 3 ethnic groups, ethnicity did not predict prior appointment of a health care agent in multivariate analysis. CONCLUSIONS: Differences in health care proxy completion rates across white, African American, and Hispanic elderly individuals in this New York City population seem to be related to potentially reversible barriers such as lack of knowledge and the perceived irrelevance of advance directives in the setting of involved family. Enhanced educational efforts of both health care personnel and patients could increase the rate of formal health care proxy appointment.

Advance Care Planning↗
PubMedDate not supplied

Cardiac effects of hemodialysis: noninvasive monitoring by systolic time intervals.

The effects of hemodialysis on cardiac performance were evaluated by systolic time intervals measured blindly in 15 chronic renal failure patients maintained free of circulatory congestion. After a mean dialysis of 8.7 hours, levels of blood urea nitrogen, serum creatinin, and potassium and body weight showed statistically significant decreases and serum calcium and hematocrit values increased; heart rate and both diastolic and systolic blood pressure did not change significantly. Left ventricular ejection time (LVET) and ejection time index (ETI) were significantly shorter, falling from within normal limits to below normal. Pre-ejection period (PEP) rose significantly. These changes are consistent with a two-fold immediate effect of hemodialysis: (1) reduction of stroke volume as reflected by decreased ETI; and (2) reduced Starling effect, with or without decreased contractility, as reflected by increased PEP.

Adolescent↗
PubMedDate not supplied

Anti-telomerase therapy suppressed glioma proliferation.

In order to determine if telomerase activity contributes to the growth of glioma cells, we constructed an anti-telomerase vector to suppress telomerase expression in glioma cells. The human telomerase (hTR)-antisense vector showed a significant suppression effect. However it did not appear to induce cell death as a stable population of cells survived more than two months following transfection. These results provide evidence that reagents aimed at inhibiting telomerase may represent a useful strategy for suppressing the growth of glioma cells. In addition to telomerase, another mechanism would also maintain telomere length, thus supporting continuous cell proliferation.

Cell Division↗
PubMedDate not supplied

Using focus group methodology in nursing.

BACKGROUND: The need to obtain quality data in a cost-efficient manner spawned an exploration of research methods. The value of focus group methodology for multiple roles in nursing became evident. METHOD: This article describes the purpose, process, and application of focus group methodology for nursing continuing education. RESULTS: Ideas for use of focus group methodology in nursing continuing education are suggested. CONCLUSION: Focus group methodology can enhance the work of nurses in continuing education roles.

Cost-Benefit Analysis↗
PubMedDate not supplied

Outcomes for patients with congestive heart failure in a nursing case management model.

Congestive heart failure is a leading cause of hospital admissions, costing an estimated $7 billion in 1990. Hospital-based nursing case management has been used to reduce costs of care while maintaining quality of care. This study describes the outcomes for 50 patients with congestive heart failure in a hospital-based nursing care management model, providing general outcomes, physiologic status, physical functioning, health knowledge, and family caregiver status. The number of medications was the only predictor of length of stay using regression analysis.

Activities of Daily Living↗