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Biomedical subjects

M Johnson

Publications and source records attributed to M Johnson.

At least 19 recordsLinked to original sources
PubMed1995

Assessment of hibernating myocardium by dobutamine stimulation in a canine model.

OBJECTIVES: The purpose of this study was to 1) develop an animal model of hibernating myocardium, and 2) evaluate the ability of dobutamine stimulation to detect hibernating myocardium using both qualitative and quantitative assessment of regional myocardial function. BACKGROUND: Left ventricular dysfunction may be due to chronic ischemia with or without myocardial infarction and may improve after coronary blood flow is enhanced by revascularization procedures. This condition has been coined "hibernating myocardium" and variably defined in recent years. The results of recent clinical studies suggest that dobutamine echocardiography may be useful for detecting viable myocardium in patients with left ventricular dysfunction. METHODS: Twenty-one dogs underwent initial operation. Sonomicrometer crystals were implanted, and baseline measurements of segment shortening and wall thickening (by echocardiography) were made. A coronary artery was ligated; the chest was closed; and measurements were repeated. Dobutamine was incrementally infused with determination of wall thickening and segment shortening at baseline and on days 3 and 7 and weeks 2 and 4 after coronary artery occlusion. Finally, the chest was reopened; the ligated vessel was bypassed; and measurements were repeated. RESULTS: Of the 10 dogs that completed the entire protocol, 7 had varying degrees of nontransmural myocardial infarction (group 1), and 3 had complete transmural myocardial infarction (group 2). In group 1, baseline function was significantly impaired compared with preligation function but increased during dobutamine infusion. When reperfused after 4 weeks, both wall thickening and segment shortening increased significantly. In group 2, significant changes were not seen during the dobutamine studies or after reperfusion. Myocardial perfusion during dobutamine infusion increased in group 1 but did not change in group 2. CONCLUSIONS: We demonstrated improvement in chronically dysfunctional myocardium after restoration of previously interrupted myocardial blood flow in dogs after nontransmural myocardial infarction, thus validating a canine model of hibernating myocardium. As assessed by two independent methods, dobutamine infusion identified hibernating myocardium in an animal model.

Animals↗
PubMed1995

Selective tumorigenesis in non-parenchymal liver epithelial cell lines by hepatocyte growth factor transfection.

Hepatocyte growth factor (HGF) has been recently suggested to contribute to tumorigenesis by an autocrine mechanism in fibroblast cells overexpressing its receptor, the MET/HGFR protein. Since epithelial cells represent the primary physiologic target of HGF, we investigated whether inappropriate expression of HGF by epithelial cells which normally express MET/HGFR may also contribute to tumorigenesis. We have transfected a full length rat HGF gene into three mouse epithelial cell lines, one derived from breast (MM55) and two (BNL CL.2 and NMuLi) representing liver non-parenchymal epithelial cells (NPEC). We confirmed the presence of the transfected gene by Southern blot analysis, the production of HGF protein by immunofluorescence, and the preservation of HGF biologic activity by bio-assay. In comparison to untransfected cells, all three HGF-transfected cell lines displayed high level MET/HGFR autophosphorylation and increased ability to proliferate in media containing low serum. The two HGF-transfected liver NPEC lines, but not the HGF-transfected mammary cell line, displayed loss of cell contact growth-inhibition and acquired a markedly increased ability to form colonies in soft agar. Furthermore, the NPEC HGF-transfected cell lines formed much larger tumors in nude mice than the untransfected counterparts, with extensive invasion and sporadic lung metastases. These results demonstrate that overexpression of HGF in at least some epithelial cells contribute to tumorigenesis, and furthermore suggest a possible role for the HGF-MET/HGFR system in the progression of certain epithelial tumors.

Animals↗
PubMed1995

"Abnormal" illness behaviour in chronic fatigue syndrome and multiple sclerosis.

OBJECTIVE: To investigate the presence of abnormal illness behaviour in patients with a diagnosis of chronic fatigue syndrome. DESIGN: A cross sectional descriptive study using the illness behaviour questionnaire to compare illness behaviour scores and illness behaviour profiles of patients with chronic fatigue syndrome and patients with multiple sclerosis. SETTING: A multidisciplinary fatigue clinic and a teaching hospital neurology outpatient clinic. SUBJECTS: 98 patients satisfying the Oxford criteria for chronic fatigue syndrome and 78 patients with a diagnosis of multiple sclerosis. MAIN OUTCOME MEASURE: Responses to the 62 item illness behaviour questionnaire. RESULTS: 90 (92%) patients in the chronic fatigue syndrome group and 70 (90%) in the multiple sclerosis group completed the illness behaviour questionnaire. Both groups had significantly high scores on the general hypochondriasis and disease conviction subscales and significantly low scores on the psychological versus somatic concern subscale, as measured in relation to normative data. There were, however, no significant differences in the subscale scores between the two groups and the two groups had identical illness behaviour profiles. CONCLUSION: Scores on the illness behaviour questionnaire cannot be taken as evidence that chronic fatigue syndrome is a variety of abnormal illness behaviour, because the same profile occurs in multiple sclerosis. Neither can they be taken as evidence that chronic fatigue and multiple sclerosis share an aetiology. More needs to be known about the origins of illness beliefs in chronic fatigue syndrome, especially as they are important in determining outcome.

Adult↗
PubMed1995

Salmeterol.

Explore the source record for details and available documents.

Adrenergic beta-Agonists↗
PubMed1995

Healing determinants in older people with leg ulcers.

A descriptive correlational design was used to identify the physiologic, therapeutic, and psychosocial determinants of leg ulcer healing in community-residing older people with venous and venous-arterial disease (N = 156). A regression model with healing rate as the dependent variable explained 49% of the variance. Increased pain when mobilizing, increased hours with limbs horizontal to the torso, and moderate and severe liposclerosis (hardening and induration of the skin) were associated with poorer healing rates. Higher wound status scores were associated with more rapid healing rates. Self-efficacy beliefs and social support were not significant factors. The findings suggest the need for early detection and management of limb pain that interferes with normal mobility. Limb position and edema assessment prior to the application of compression bandages is recommended, with bandages that provide clients with high compression when ambulant and low compression when resting being potentially beneficial.

Aged↗
PubMed1995

The role of NMDA receptor systems in neuropeptide responses to stimulants of abuse.

High doses of stimulants of abuse, such as methamphetamine and cocaine, cause significant increases in the content of neurotension- and dynorphin-like immunoreactivity in the striatum and nucleus accumbens (approximately 200-600% of control) in the rat. These changes in neuropeptide content are caused by stimulation of dopamine D1 receptors and prevented by the glutamate NMDA receptor antagonist, MK 801. Stimulation of the NMDA receptor with N-methyl-D-aspartate results in increases in the neuropeptide levels like that caused by methamphetamine and cocaine. These findings demonstrate that stimulants of abuse profoundly influence neurotensin and dynorphin pathways associated with extrapyramidal and limbic structures by an interaction of activated dopamine D1 and glutamate NMDA receptors.

Animals↗
PubMed1995

Osteogenic protein-1 induces dendritic growth in rat sympathetic neurons.

Sympathetic neurons from perinatal rat pups extend only a single axon when maintained in culture in the absence of glia and serum. Exposure to recombinant osteogenic protein-1 (OP-1) selectively induces the formation of dendrites that correctly segregate and modify cytoskeletal and membrane proteins and form synaptic contacts of appropriate polarity. OP-1 requires nerve growth factor (NGF) as a cofactor, and, in the presence of optimal concentrations of NGF, OP-1-induced dendritic growth from cultured perinatal neurons is comparable to that observed in situ. Sympathetic neuroblasts that had not formed dendrites in situ also responded to OP-1 in culture, indicating that OP-1 can cause de novo formation as well as regeneration of dendrites. These data imply that specific signals can regulate the development of neuronal shape and polarity.

Animals↗
PubMed1995

Fluticasone propionate--an update on preclinical and clinical experience.

Fluticasone propionate (FP) is a novel androstane glucocorticoid with potent anti-inflammatory activity which has been effectively used, intranasally, as therapy for seasonal and allergic perennial rhinitis. When taken by the inhaled route, FP has shown significant therapeutic efficacy in the management of asthma. Fluticasone propionate is a highly lipophilic molecule with good uptake, binding and retention characteristics in human lung tissue. Fluticasone propionate has high glucocorticoid receptor selectivity and affinity, demonstrating rapid receptor association and slow receptor dissociation. In vitro, FP has been shown to potently inhibit T lymphocyte proliferation, cytokine generation, tumour necrosis factor alpha (TNF-alpha)-induced adhesion molecule expression, interleukin-5-induced eosinophilia, mucosal oedema and toluene 2,4-diisocyanate-induced mast cell proliferation, while promoting secretory leucocyte protease inhibitor production and eosinophil apoptosis. In human studies, FP has demonstrated marked vasoconstrictor potency in normal subjects and inhibited antigen-induced mucosal platelet activating factor/eicosanoid production, T lymphocytes and CD25+ cells in patients with rhinitis. Biopsy data from mild asthmatics demonstrate FP-associated reduction in CD3, CD4, CD8 and CD25 cells, with an accompanying reduction in eosinophil and mast cell markers. Clinical studies have evaluated lung function, bronchial reactivity, exacerbation rates and oral corticosteroid-sparing effect. Results show that FP has at least twice the clinical potency of beclomethasone dipropionate and budesonide. This appears to be achieved without an accompanying increase in systemic effects, suggesting a therapeutic index which may be higher than other currently available inhaled corticosteroids.

Androstadienes↗
PubMed1995

A simple technique for fabrication of transmission block for concomitant treatment of bilateral anterior inguinal lymphatics and pelvic/perineal structures.

The efficacy of transmission block technique with contiguous photon irradiation of inguinal as well as pelvic and perineal structures has been reported in literature. In this paper, a simple and accurate method for the proper fabrication of transmission block has been described and also demonstrated to be effective and useful. The procedures for a precise geometrical alignment and dose verification are also detailed.

Anus Neoplasms↗
PubMed1995

Effect of germanium-132 on galactose cataracts and glycation in rats.

Germanium compounds have been shown to be effective in preventing the formation of advanced glycation end-products and for reversible solubilization of glycated proteins. As protein glycation has been proposed to play a role in lens opacification, we initiated studies to evaluate the effects of 2-carboxyethyl germanium sesquioxide (germanium compound 132 or Ge-132) on galactose-induced cataractogenesis. For this study young Sprague-Dawley rats were fed a 50% galactose diet. One group of rats received topical saline and another group was administered Ge-132 in saline four times a day. The lenses were periodically examined with an ophthalmoscope and at desired intervals processed for light and scanning electron microscopy. Our observations, beginning at 3 days and continuing to 21 days of galactose feeding, exhibited the characteristic galactose-induced morphological alterations, which include the formation of vacuoles, cysts, membrane disruption and swelling of fibers and epithelial cells as well as disorganization of the bow in lenses of rats in both groups. However, in the majority of rats administered Ge-132 these alterations were delayed as compared to the lenses of rats administered saline. Our findings show that, although the initiation, progression and pattern of lens opacification in rats receiving saline and Ge-132 were similar, in the majority of lenses the progression and establishment of mature cataracts in the Ge-132 group of rats were delayed. Analysis of the water-soluble and water-insoluble lens-protein fractions for glycated proteins showed increased levels of the Amadori products and advanced glycation related fluorescent products in galactosemic rats treated with saline eye drops. In rats receiving the topical Ge-132 treatment the levels of these glycation products were substantially reduced to levels lower than control values. Prevention of glycation seems to be a mechanism by which cataract progression is delayed.

Animals↗
PubMed1995

The power of social judgement: struggle and negotiation in the nursing process.

In this paper we discuss an alternative view of the nursing process as it is experienced by both patients and nurses. The current conception of the nursing process is that it is a benevolent activity which aims to render care more individualized or person-centred. Its rhetoric usually includes notions of mutuality in goal setting, openness and collaboration between patients and nurses. We will suggest that such a view is idealized and has little basis in empirical reality as it is experienced by both nurses and patients. Rather, nurse-patient relations are beset by conflict and struggle, frequently resulting in the acquiescence of patients to the nursing and the medical goals of care. On the basis of an ethnography of a hospital medical ward, we will describe a process of social judgement and set it into a discussion of the social context where an unequal balance of power is integral to provider-recipient relations. Our account will focus upon four categories through which judgemental labelling may be analysed. These are assessing, negotiation, struggling and acquiescing. Of special interest to us are strategies which nurses used to maintain excellent care in the context of negative social judgements, and the place social judgement may play in moral decision-making. We emphasize the strengths which rich qualitative data have in relation to previous survey approaches of this phenomenon, whilst recognising the limitations of so focused a study.

Humans↗
PubMed1995

Essential thrombocytosis: underemphasized cause of large-vessel thrombosis.

PURPOSE: The purpose of this study was to describe the clinical course of patients seen with large-vessel thrombosis in association with essential thrombocytosis (ET). METHODS: This study was a retrospective review of all patients treated for large-vessel thrombosis caused by ET during a 2-year period at University of Washington teaching hospitals. RESULTS: Five patients presented with arterial (femoral-popliteal-tibial: aortic), portal (two cases), or systemic venous (inferior vena cava) thrombosis and required operation. Two were known to have ET; in three others ET was diagnosed after operation when platelet counts persistently in excess of 500,000/mm3 were noted. The diagnosis of ET was established in each case by ruling out causes of reactive thrombocytosis and (in the three new cases) by evidence for megakaryocyte hyperplasia on bone marrow biopsy. Platelet counts in all five patients were reduced to normal levels by cytoreductive therapy, and no further thrombotic episodes have occurred during 18 months (mean) of follow-up. During this 2-year period ET accounted for more large-vessel thrombotic complications in our institutions than all other more frequently described hypercoagulable states combined. CONCLUSIONS: ET is an underemphasized cause of large-vessel thrombosis.

Adult↗
PubMed1995

Face processing impairments after amygdalotomy.

We report an investigation of face processing impairments in D.R., a 51-year-old woman with a partial bilateral amygdalotomy. D.R. was able to recognize pre-operatively familiar faces, but she showed generalized problems of name retrieval and a more circumscribed deficit affecting the recognition of faces learnt post-operatively. In contrast to her poor memory for new faces, D.R.'s ability to match simultaneously presented photographs of unfamiliar faces was unimpaired. However, D.R. also experienced deficits in expression processing which compromised the recognition of emotion from people's faces: she was poor both at matching and at identifying photographs of emotional facial expressions. In addition, her interpretation of eye gaze direction was defective, showing a more general problem in reading social signals from the face. The presence of impairments affecting the learning of new faces and the comprehension of gaze direction and facial expressions of emotion is consistent with the hypothesis of a role for the amygdala in learning and social behaviour.

Amygdala↗
PubMed1995

Maternal plasma concentrations of insulin-like growth factor binding protein-1 and placental protein 14 in multifetal pregnancies before and after fetal reduction.

The aim of this study was to investigate the changes in maternal plasma insulin-like growth factor binding protein-1 (IGFBP-1) and placental protein 14 (PP14) in multifetal pregnancies before and after embryo reduction. Maternal plasma IGFBP-1 and PP14 were measured serially in three groups of pregnant women at 8-21 weeks gestation. Groups 1 and 2 were 12 singleton and 12 twin pregnancies achieved after in-vitro fertilization (IVF). Group 3 comprised 26 women with multifetal pregnancies undergoing embryo reduction to twins. In the IVF pregnancies maternal plasma IGFBP-1 and PP14 increased with gestation to reach a peak at 20 and 10 weeks respectively; the mean concentrations in twin pregnancies were significantly higher than in singletons. In multifetal pregnancies the mean plasma concentration of both proteins was similar to that of IVF twin pregnancies before reduction; after reduction, the values fell to less than those of twins. These findings suggest that the maximum secretory capacity of the endometrium is achieved with twin pregnancies. In multifetal pregnancies undergoing iatrogenic reduction to twins, total residual endometrial function was less than in twin conceptions.

Carrier Proteins↗
PubMed1995

First-line nurse managers in rural hospitals: perceptions of career success.

First-line nurse managers in small rural hospitals are essential to organizational survival, yet little is known about such individuals. A pilot study comparing demographic characteristics and career success perceptions of first-line nurse managers from rural settings with doctorally prepared nurses found that despite age and educational differences, personal characteristics identified as contributing to career success were remarkably similar in both groups. First-line nurse managers generally credited family members with greater degrees of career influence than did their more educated colleagues. However, both groups saw themselves as primarily responsible for their own career success. This information may assist rural hospitals and nursing personnel to enhance their strategic position in the unstable environment of health care reform.

Adult↗
PubMed1995

Rediscovering unpopular patients: the concept of social judgement.

Nurses have known about unpopular patients for over two decades. Influential studies such as Stockwell's in the UK have had considerable impact upon students of nursing. Stockwell's book, The Unpopular Patient, is widely cited and was reprinted in 1984. Further, a critical review of the wider literature by Kelly & May threw down a challenge to researchers to investigate the phenomenon using an interactionist perspective and ethnographic methods. This paper reports a study which should begin to reinforce doubt that evaluative labels, unpopular or otherwise, are in any way 'predictable', as Stockwell and a host of others have hoped and assumed. The process through which evaluative labels of people are socially constructed is explored and the context, explanations and some consequences of what we call social judgement are discussed.

Adult↗