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J Roberts

Publications and source records attributed to J Roberts.

At least 271 records · Page 15Linked to original sources
PubMed1995

Information-seeking strategies and data utilisation: theory and practice.

This paper explores the twin processes of information-seeking and data utilisation, two key components of the problem-solving process. The assessment and management of pain are examined as important exemplars of where varying degrees of skill and efficiency in these key processes emerge from the research conducted to date. It is suggested that if performance is to be enhanced, then a review of the current use of the nursing process, the main vehicle for the operationalisation of problem-solving in practice is required, coupled with further empirical study directed towards exploring how and when the development of advanced cognitive skills is best facilitated.

Clinical Competence↗
PubMed1995

Prenatal cocaine exposure alters norepinephrine release from cardiac adrenergic nerve terminals.

The effect of prenatal cocaine exposure on the development of the cardiac adrenergic nervous system was assessed in neonatal rabbits. Pregnant does received cocaine (4 mg/kg, i.v., bid) or saline during gestational days 8 to 29. Hearts were obtained on postnatal days 10, 20, 30, and 50. Adrenergic nerve function was assessed by measuring 3H-norepinephrine (NE) uptake and 3H-NE release from cardiac synaptosomes. NE uptake increased with postnatal age and was not affected by cocaine exposure. K(+)-induced NE release increased with age, was significantly less in cocaine exposed rabbits compared to saline exposed rabbits at days 10, and 20, but was similar at days 30 and 50. NE release induced by ionomycin, a Ca2+ ionophore, did not change with age, was significantly greater in cocaine exposed rabbits compared to saline exposed rabbits at days 10, 20, and 30, but was similar at day 50. Wet heart weight, heart weight per body weight, and NE content of the hearts were not affected by cocaine exposure. These results suggest that prenatal cocaine exposure delays the development of the mechanisms responsible for Ca2+ influx during K(+)-induced depolarization and increases the neurosecretory response to intracellular Ca2+.

Adrenergic Fibers↗
PubMed1995

More effective and less expensive: lessons from five studies examining community approaches to care.

Does the nature of community health services used by chronically ill clients and their caregivers have an impact on utilization of services, expenditure and well-being outcomes? A series of five studies, (four historic cohort and one randomized trial) examined clients suffering from a variety of chronic conditions in a number of community settings in different regions of Southern Ontario. Study sample composition and size varied. Each study was designed to quantify the well-being outcomes, and expenditure associated with different community approaches is covered under a nation-wide system of health insurance plans. As a collective, these studies represent increasing methodological rigor. Multiple-perspective client well-being outcome measures were used. Caregiver burden was also analyzed. A common approach to quantification and evaluation of expenditure for service consumption was applied across all five studies. The nature of community health services (proactive versus reactive approaches to care) was found to have direct and measurable impact on total expenditure for health service utilization and client well-being outcomes. A recurring pattern of lower expenditure for community health service utilization and equal or better client outcomes was associated with well-integrated proactive services when compared with individual fragmented, reactive approaches to care. The main lesson emerging from examining the five studies on approaches to community care is that it is as, or more, effective and less expensive to offer complete proactive health care services to chronically ill people in the early stages of their illness than to provide services on demand in a piecemeal manner.

Caregivers↗
PubMed1995

Localization of serotonin-4 receptors in the striatonigral pathway in rat brain.

Rats were injected unilaterally with 6-hydroxydopamine either in the medial forebrain bundle or in the dorsolateral substantia nigra. Another group was injected unilaterally with kainate in the striatum. The loss of neurons was assessed by a reduction in tyrosine hydroxylase-like immunoreactivity for dopaminergic neurons, and choline acetyltransferase-like and glutamate decarboxylase-like immunoreactivities for cholinergic and GABAergic neurons, respectively. Brain sections also were analysed by autoradiography on 20 micron sections with the radio-iodinated serotonin-4 receptor antagonist [125I]SB 207710 [Brown A. M. et al. (1993) Br. J. Pharmac. 110, 10P]. Kainate injections in the striatum resulted in loss of choline acetyltransferase- and glutamate decarboxylase-like immunoreactive cell bodies in this area. There was also a decrease in glutamate decarboxylase-like immunoreactivity on the ipsilateral side in the substantia nigra and entopeduncular nucleus. These changes were accompanied by substantial (> 50%) decreases in [125I]SB 207710 binding in both the ipsilateral striatum (confined to the lesioned area) and substantia nigra, with no change in either the nucleus accumbens or the globus pallidus. There was also significant loss of [125I]SB 207710 binding in the ipsilateral entopeduncular nucleus. 6-Hydroxydopamine lesions placed either in the medial forebrain bundle or in the substantia nigra failed to decrease [125I]SB 207710 binding in any of these areas, although there was total loss of tyrosine hydroxylase-like immunoreactive terminals in the striatum and cell bodies in the nigra. We conclude that serotonin-4 receptors are present on projection neurons, both on their perikarya in the striatum and terminals in the nigra and entopeduncular nucleus. It is likely that these receptors are located on the GABAergic projection neurons and possibly on cholinergic and GABAergic interneurons. However, serotonin-4 receptors are not located on dopaminergic neurons, either on their cell bodies in the substantia nigra or terminals in the striatum.

Animals↗
PubMed1995

Detection of hepatitis C after liver transplantation. Four serologic tests compared.

To determine the best method for detecting HCV infection in immunosuppressed patients, stored frozen serum from 101 liver transplant recipients was tested for hepatitis C virus. Each sample was tested by four assays. HCV RNA was detected by both polymerase chain reaction (PCR) and branched DNA signal amplification. Antibody to HCV was determined using second-generation enzyme-linked immunoassay (EIA) and recombinant immunoblot assay. Forty one transplant recipients met the working definition for true positives of HCV infection. Of these "true positives," 98% were positive by HCV RNA PCR assay, 88% by b-DNA signal amplification assay, 88% by anti-HCV EIA, and 63% demonstrated two or more reactive bands on recombinant immunoblot. Five of 57 (9%) HCV-antibody negative recipients had HCV RNA detected by both methods. Of 44 HCV enzyme-linked immunoassay (EIA) repeatedly reactive samples, the recombinant immunoblot was negative in 2 and indeterminate in 13. HCV RNA was present in 9 of 13 recombinant immunoblot indeterminate sera. Nine EIA repeatedly reactive sera were negative by both tests for HCV RNA. In liver transplant recipients, HCV infection is best determined by measurement of HCV RNA. Antibody formation may be delayed or suppressed in a minority of patients despite > 10(9) equivalents/L (> 10(6)/mL) of HCV RNA in serum. Recombinant immunoblots with a single reactive band pattern often indicate HCV infection in immunosuppressed patients.

Hepacivirus↗
PubMed1995

Expression of G protein alpha subunits in the aging cardiovascular system.

Alterations in responsiveness to stimulation of G protein-coupled receptors in the cardiovascular system have been noted during aging and may be due to changes in the G proteins. The levels of G protein alpha subunits and their mRNAs were examined in the aorta and heart of adult (6-month-old) and senescent (24-month-old) Fischer 344 rats. Western blot analysis using anti-Gs alpha antiserum revealed 4 bands in the aorta (38, 42, 45, and 52 kD). The 42 kD band decreased significantly in 24-month-old rats, whereas the other bands did not change. Western blots using anti-Go alpha and anti-Gi alpha revealed single bands of 39 kD and 41 kD respectively, which decreased significantly in the aortas from 24-month-old rats. There were no significant changes in the levels of G alpha mRNAs in the aorta during aging. In the heart, anti-Gs alpha antiserum detected 3 bands (42, 45, and 52 kD) which did not change with age. Levels of Gi alpha (41 kD) and Go alpha (39 kD) also did not change with age in the heart. The mRNAs for Gi2 alpha and Gi3 alpha were significantly increased in the heart, but there was no change in Go alpha or Gs alpha mRNAs. Reduced expression of Gi alpha may provide the molecular basis for alterations in receptor responsiveness in the aging vasculature. Altered expression of G protein alpha subunits does not appear to account for age-related alterations in cardiac function.

Aging↗
PubMed1995

Age-related changes in cardiac norepinephrine release: role of calcium movement.

The purpose of this study was to determine if the age-related decrease in norepinephrine (NE) release from cardiac adrenergic nerve terminals is due to a defect in Ca2+ movement into the nerve terminal or to an alteration in Ca2+ activation of intracellular events leading to NE release. NE release was assessed in cardiac synaptosomes prepared from 6- and 24-month-old male F344 rats. K(+)-induced NE release was significantly greater in young vs old rats. Raising extracellular [Ca2+] increased NE release, but NE release always remained higher in the younger animals. Ionomycin, a Ca2+ ionophore, induced NE release from cardiac synaptosomes, and there was no age difference in the response. The age-related reduction in NE release induced by K+ and the capacity of ionomycin to induce similar NE release in young and old cardiac synaptosomes points to a reduction in Ca2+ movement during depolarization.

Aging↗
PubMed1995

The effectiveness and efficiency of health promotion in specialty clinic care.

Chronic illnesses make up the majority of health problems in North America. Many chronically ill persons adjust over time to their illnesses; however, there remains a small but important group of those less adjusted, who are concentrated in specialty clinics and are high users of health care resources. This randomized clinical trial investigated the impact of health promotion interventions in the form of problem-solving counseling or phone support that augmented conventional clinic medical care. Chronically ill, poorly adjusted outpatients (n = 293) attending clinics were randomly assigned to receive additional problem-solving counseling, phone call support, or neither. Psychosocial adjustment to illness, utilization, and expenditures of health services were the main outcomes measured. There were no overall significant differences between groups in their change in psychosocial adjustment and expenditures for health and social care. However, interaction analyses (P < 0.05) gave an indication of who might benefit from these interventions. Those who lived alone and infrequently used problem-solving behaviors to cope with their illness significantly improved their adjustment to illness and had fewer health service expenditures if they received problem-solving counseling. Supportive telephone calls were most effective for those who lived with someone and frequently used problem-solving coping behaviors. These findings suggest that health promotion services should be targeted to outpatients described by specific social support and coping characteristics.

Adaptation, Psychological↗
PubMed1995

The effect of selegiline on the peripheral pharmacokinetics of levodopa in young volunteers.

The plasma pharmacokinetics of levodopa were studied in eight healthy young subjects following an i.v. infusion of 50 mg over 5 min. Subjects were studied on two occasions in random order following treatment with carbidopa; on one occasion they were pretreated with selegiline (four doses of 10 mg over the preceding 3 days) and on the other with a placebo. The mean plasma concentration-time curves on each occasion were essentially superimposable and there were no significant differences in any calculated pharmacokinetic parameter. Selegiline does not significantly alter the distribution or elimination of levodopa from plasma.

Adult↗
PubMed1995

The transition to air breathing in fishes. V. Comparative aspects of cardiorespiratory regulation in Synbranchus marmoratus and Monopterus albus (Synbranchidae)

Extreme heart-rate lability accompanies the air-breathing cycles of Synbranchus marmoratus and Monopterus albus. When air is taken into the buccopharyngeal air-breathing organ of these fishes, heart rate increases sharply above pre-inspiration rates of 3&shy;25 beats min-1 to as high as 40&shy;45 beats min-1. With time, and as O2 is depleted from the air-breathing organ, heart rate gradually declines and drops to its lowest level with, or following, exhalation. Relationships between air breathing and sinus arrhythmia in M. albus were investigated by injecting variable gas volumes and O2 mixtures into the cannulated air-breathing organ. Tests were also carried out on undisturbed fish breathing volitionally in atmospheres containing different O2 levels. Both the volume and O2 content of the inspired gas affect the level and duration of inspiration tachycardia. Additional factors affecting tachycardia are the heart rate prior to inspiration and the time since air was last held. S. marmoratus is a non-obligatory air breather and uses rhythmic branchial aquatic respiration to a greater extent than M. albus, an obligate air breather. While the heart rates of both species are increased during aquatic ventilation, the higher heart rate to ventilation ratio in S. marmoratus (2&shy;3 versus approximately 1 in M. albus) seems attributable to its more proficient aquatic respiratory system. The available cardiorespiratory data for air-breathing fishes indicate that the scope of air-inspiration tachycardia is smaller in lungfishes and other primitive species than in most teleosts. This difference is mainly attributable to the greater chronotropic effect of sympathetic cardiac innervation in teleosts.

Journal Article↗
PubMed1995

Hydrogen peroxide induces 21-aminosteroid-inhibitable F2-isoprostane production and cytolysis in renal tubular epithelial cells.

F2-isoprostanes are the newly identified reactive oxygen species-catalyzed peroxidation products of arachidonate. The infusion of these prostaglandin F2-like prostanaoids into the rat kidney induces profound parallel reductions in RBF and GFR, suggesting that these metabolites may be partly responsible for the hemodynamic alterations seen in free radical-linked acute renal injury models. The present study examined directly in renal proximal tubular (LLC-PK1) cells whether hydrogen peroxide, a reactive oxygen species implicated in many models of acute renal injury, induces F2-isoprostane production and whether its production can be inhibited by the recently synthesized lipid peroxidation inhibitor 21-aminosteroid (lazaroid U-74389G). The incubation of LLC-PK1 cell layers with hydrogen peroxide for 3 h resulted in a dose-related six-fold increase in F2-isoprostane production, measured by the gas chromatographic-mass spectroscopic method. The preincubation of cells with 21-aminosteroid prevented hydrogen peroxide-induced F2-isoprostane production, a finding also demonstrable with other lipid peroxidation inhibitors, e.g., 2-methyl aminochroman (U-83836E) and diphenyl-p-phenylenediamine. Besides inhibiting isoprostane production, 21-aminosteroid reduced hydrogen peroxide-induced lipid degradation and peroxidation, and protected the cells against hydrogen peroxide-induced cytolysis. The novel finding that hydrogen peroxide induces 21-aminosteroid-inhibitable F2-isoprostane production in renal epithelial cells supports the in vivo report that its levels are elevated in reactive oxygen species-linked renal injury models such as ischemia-reperfusion. Besides direct cell injury, lipid peroxidation by generating F2-isoprostanes may further contribute to renal dysfunction through a vasoconstrictive mechanism. Thus, the inhibition of excess F2-isoprostane production may be one of the additional mechanisms, besides cytoprotection, by which antioxidants ameliorate renal dysfunction in experimental models of acute renal injury.

Animals↗
PubMed1995

Scintigraphic imaging with 123I-metaiodobenzylguanidine as a marker of cardiac adrenergic neurotransmission in the rat.

This study was performed to determine if 123I-metaiodobenzylguanidine (123I-MIBG) could be used to create scintigraphic images of the rat heart and to determine if this method could be used to estimate cardiac norepinephrine turnover in the intact animal. Male F344 rats were injected i.v. with 200-350 muCi of 123I-MIBG. Beginning at 5 min after the injection, scintigraphic images were made every 30 min for 5 h. The half-life of 123I-MIBG retention within the heart during the 5 h of the experiment was determined by plotting the log of the counts for each image vs. time. The half-life of cardiac 123I-MIBG was 3.44 +/- 0.17 h with a rate constant of 0.21 +/- 0.01 (hr-1). In a separate experiment, methacholine, a parasympathomimetic agonist, was given after the injection of 123I-MIBG and increased 123I-MIBG efflux. Cardiac 123I-MIBG uptake was reduced by 65% in rats sympathetically denervated with 6 hydroxy dopamine indicating that 123I-MIBG is accumulating for the most part in adrenergic nerve terminals. We conclude that scintigraphic imaging with 123I-MIBG may be a useful procedure for estimating cardiac adrenergic nervous system activity in the intact animal.

3-Iodobenzylguanidine↗
PubMed1995

The feasibility and accuracy of anonymized record linkage to estimate shared clientele among three health and social service agencies.

This study was designed to test the effectiveness of three computerized methods of record linkage, using minimal identifiers. The goal of the linkage was to determine the proportion of persons receiving Public Health Nursing Services (n = 5,749) who also receive income assistance from the region (n = 38,800) or the province (n = 16,741). The first linkage method was based on full agreement of a number of variables (deterministic matching) and the second was based on the likelihood of the match (probabilistic matching). The third method combined information from methods 1 and 2. Method 3 proved to be the most effective linkage technique, with a specificity of 0.98 and sensitivity of 0.94. The linkage showed that only 17% of the Public Health clientele received income assistance from the region or province, much lower than expected. Factors which have probably led to an underestimate are discussed.

Confidentiality↗
PubMed1995

Developmental changes in static admittance and tympanometric width in infants and toddlers.

Longitudinal measures of peak-compensated static acoustic admittance and tympanometric width are reported for infants and toddlers from 6 months to 30 months of age, based on over 1600 assessments of 88 children during a 24-month period. The subjects were all African-American children in full-time day care. Significant age effects were observed, with younger children displaying lower static admittance values and wider tympanograms. The results of this investigation underscore the importance of age- and population-specific norms when using acoustic admittance measures to evaluate middle ear status in children.

Acoustic Impedance Tests↗
PubMed1995

Helicobacter pylori infection does not increase gastric antrum mucosal cell proliferation.

OBJECTIVES: Gastric carcinoma is the world's second most common cancer. Recent studies suggest an association between Helicobacter pylori and gastric carcinoma. The aim of this study was to address the effects of H. pylori infection on gastric antrum mucosal cell proliferation. METHODS: Forty patients undergoing upper endoscopy for standard indications were included in the study. A rapid urease test was used to determine the presence of H. pylori. Epithelial cell proliferation was determined by immunohistochemical techniques utilizing monoclonal antibody to bromodeoxyuridine. RESULTS: There were no significant differences in the number of labeled cells and in the proliferation fraction (p > 0.1) when patients with H. pylori were compared with those without, and when those over the age of 50 were compared to those under 50. The presence of ulcers similarly had no effect (p > 0.1). CONCLUSION: Helicobacter pylori infection does not increase gastric antrum mucosal cell proliferation.

Age Factors↗