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Biomedical subjects

K Robinson

Publications and source records attributed to K Robinson.

At least 181 records · Page 10Linked to original sources
PubMed1991

Hyperhomocysteinaemia and multiple aneurysms.

Homozygous homocystinuria, the most common genetic disorder of transulphuration, is associated with elevated plasma concentrations of homocystine, homocysteine, multiple clinical abnormalities and life-threatening thromboembolism. Several instances of vascular aneurysms have also been documented. More recently, an association between premature occlusive vascular disease and the heterozygous state has been proposed. We now report an unusual case in whom multiple aneurysms were associated with heterozygous homocystinuria.

Amino Acid Metabolism, Inborn Errors↗
PubMed1991

In-hospital prognosis of patients with fasting hyperglycemia after first myocardial infarction.

OBJECTIVE: To investigate the incidence and prognostic significance of fasting hyperglycemia in a large group of patients with a first myocardial infarction. RESEARCH DESIGN AND METHODS: Blood glucose was measured after an 8-h overnight fast in 752 patients with a first myocardial infarction. Three groups of patients were identified: patients with normal fasting blood glucose (92.5%), patients with fasting hyperglycemia but no prior history of glucose intolerance (3%), and patients previously known to have diabetes mellitus (4.5%). RESULTS: The fasting hyperglycemic patients were significantly older and had significantly more in-hospital complications than the normal blood glucose group. Previously known diabetic subjects tended to be older and had more mechanical complications postinfarction than the group with normal blood glucose but the difference did not reach statistical significance. There was no significant difference between the diabetic subjects and patients with fasting hyperglycemia in mean age and in-hospital prognosis. CONCLUSIONS: Fasting hyperglycemia detected after a first myocardial infarction is associated with a poor in-hospital prognosis that was not due to larger infarct size, as reflected in peak levels of cardiac enzymes. The measurement of a fasting blood glucose level provides additional information in identifying high-risk groups of patients postinfarction.

Blood Glucose↗
PubMed1990

A teratological assessment of coal liquefaction products in the rat.

Teratogenicity of coal liquefaction products (CLP) was assessed in the pregnant rat. Three product streams of CLP (medium, hydrotreated medium and heavy fractions) were each administered dermally on Sprague-Dawley rats at doses of 125, 250 or 500 mg kg-1 day-1 from Day 6 through to Day 15 of gestation. Depressed maternal weight gain and reduced number of fetuses resulting from an increased resorption rate, decreased fetal weight and retarded ossification were observed in the group treated with the heavy fraction at a dose of 500 mg kg-1 day-1. The heavy fraction at 500 mg kg-1 day-1 also caused anaemia and increased liver and spleen weights in dams. The dams exposed to the highest dose of three CLP fractions had mild and adaptative hepatic changes consisting of increased cytoplasmic eosinophilia and nuclear anisokaryosis. No treatment-related histological changes were observed in fetuses. None of the fractions demonstrated any teratological effects.

Abnormalities, Drug-Induced↗
PubMed1990

Stability of plasma amiodarone levels during chronic oral therapy.

The variability of plasma amiodarone levels in 51 patients receiving chronic oral therapy over 4-53 (median 19) months was examined; 3-14 (median 5) plasma samples were obtained. After a loading dose, most patients received either 200 mg or 400 mg a day. Mean plasma amiodarone concentration was 1.2 +/- 0.6 mg/l and mean plasma desethylamiodarone concentration was 1.2 +/- 0.5 mg/l. No relationship was seen between height and weight and plasma concentrations. Dose was a significant predictor of plasma level (p less than 0.01) although it was a poor predictor of steady state amiodarone concentration.

Administration, Oral↗
PubMed1990

Atrial fibrillation in hypertrophic cardiomyopathy: a longitudinal study.

The clinical outcome of 52 consecutive patients with hypertrophic cardiomyopathy who developed paroxysmal (less than 1 week) or established (greater than or equal to 1 week) atrial fibrillation between 1960 and 1985 was examined retrospectively and compared with that of a matched group of patients with hypertrophic cardiomyopathy and sinus rhythm. Follow-up study until death or the present ranged from 6 months to 24 years (median 11 years) from diagnosis and from 6 months to 22 years (median 7 years) from the onset of atrial fibrillation. Atrial fibrillation was present in 6 patients at the time of diagnosis, whereas it developed subsequently in 46. The acute onset of arrhythmia was associated with a change in symptoms in 41 (89%) of the 46. After initial treatment of acute atrial fibrillation, sinus rhythm was restored in 29 (63%) of the 46 patients; 43 (93%) of the 46 returned to their original symptom class. Stepwise logistic regression revealed that shorter duration of arrhythmia and amiodarone therapy were the most powerful predictors of return to sinus rhythm. Sinus rhythm was maintained during a median follow-up period of 5.5 years in 22 of the 29 patients in whom it was restored after initial therapy. During follow-up study, 25 of the 52 patients were treated with conventional therapy alone and 7 with amiodarone alone. Amiodarone therapy was associated with maintenance of sinus rhythm, fewer alterations in drug therapy, fewer embolic episodes and fewer attempted direct current cardioversions (during a shorter follow-up period).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

The relationships between social skills, social support, self-esteem and burden in adult caregivers.

The purpose of this study was to explore the relationships between social skills, self-esteem, social support and burden in a sample of adult caregivers. The Gambrill and Richey Assertion Inventory, Rosenberg's Self-Esteem Scale, Montgomery's Objective and Subjective Burden Scale, Norbeck's Social Support Questionnaire and Sarason's Social Support Questionnaire were administered to a convenience sample of 31 caregivers. Unassertive caregivers had less available social support. Those caregivers who felt more discomfort in situations also had less available social support. Caregivers who had significantly more affection, affirmation and aid from within their social network were found to have higher self-esteem. Those with lower self-esteem reported losing a greater number of important relationships in the past year. Nonassertive caregivers were more likely to experience lower subjective burden.

Adult↗
PubMed1990

A mathematical model of electrophysiological activity in a bullfrog atrial cell.

We have developed a model of cardiac atrial electrical activity based on voltage-clamp measurements obtained from single cells isolated from the bullfrog atrium. These measurements have allowed us to simulate a number of processes thought to be important in action potential initiation, repolarization, and the excitation-contraction (EC) coupling process. In this atrial model, the cell membrane contains both channel-mediated (Na+, Ca2+, inward rectifier K+, delayed rectifier K+, linear background leak) and transporter-mediated (Na(+)-K+ pump, Na(+)-Ca2+ exchanger, Ca2+ pump) currents. The cell is surrounded extracellularly by a diffusion-limited space. The intracellular volume contains Ca2(+)-binding proteins (calmodulin, troponin). The model makes several important predictions. 1) Incomplete inactivation of the Ca2+ current provides an inward current the maintains the plateau of the action potential. 2) Activation of the delayed rectifier K+ current initiates repolarization. 3) Due to Ca2+ buffering by myoplasmic proteins the Na(+)-Ca2+ exchanger current is relatively small and has little influence on repolarization. 4) The Na(+)-K+ pump current does not play a major role in repolarization. 5) K+ accumulation and Ca2+ depletion may occur in the extracellular spaces. 6) Modulation of EC coupling is governed by interactions between the myoplasmic Ca2(+)-binding proteins; specifically, the inotropic "positive staircase effect" may be explained by interactions between Ca2+ and Mg2+ at a competitive binding site on troponin. When considered in conjunction with the results of our model of primary pacemaking in the sinus venosus [Rasmusson et al., Am. J. Physiol. 259 (Heart Circ. Physiol. 28): H352-H369, 1990], this atrial model shows how the presence or absence of certain transmembrane currents can change action potential characteristics and consequently alter the relative influence of the various transporter-mediated and channel-mediated currents.

Action Potentials↗
PubMed1990

Adjuvant therapy for intracoronary stents. Investigations in atherosclerotic swine.

Early thrombosis has complicated human stent implantation in several trials. To determine the best anticoagulation/antiplatelet therapy to maintain stent patency after percutaneous transluminal coronary angioplasty, we implanted the flexible balloon-expandable coil stent into the left anterior descending coronary artery of 28 atherosclerotic 8-month-old Hanford miniature swine. Animals were randomly assigned to one of three treatment groups: group A, aspirin (1 mg/kg/day) and dipyridamole (1 mg/kg three times a day); group B, aspirin and dipyridamole (same doses) plus Coumadin (dose required to prolong prothrombin time 1.3-1.5-fold that of normal); and group C, control. Adjuvant therapy was begun 3 days before stenting. Two pigs (one from group A and one from group B) died during implantation, both without thrombosis. Twenty-six animals survived until follow-up angiography and sacrifice at 1 month. No occlusive thrombosis of the stent occurred in survivors. Reduction of the stent lumen diameter was observed in every case at follow-up. Percent lumen reduction was 19% in group A, 26% in group B, and 24% in group C. Marked smooth muscle cell hyperplasia was seen by light and transmission electron microscopy at stent struts. Scanning electron microscopy of the luminal surface showed a variable morphology consisting of normal endothelium, adherent leukocytes, stellate periluminal cells, and occasional fibrin strands and red blood cells. Luminal narrowing was not affected by anticoagulation therapy, antiplatelet drugs, cholesterol level, or stent sizing. We conclude that occlusive thrombosis does not complicate stent implantation in this model but that substantial luminal narrowing due in part to smooth muscle hyperplasia does occur. The significance of luminal narrowing at the stent site requires further study.

Angiography↗
PubMed1990

Time dependent inhibition of xanthine oxidase in irradiated solutions of folic acid, aminopterin and methotrexate.

The xanthine oxidase catalyzed oxidation of hypoxanthine was followed by monitoring the formation of uric acid at 290 nm. Inhibition of xanthine oxidase occurs in aqueous solutions of folic acid methotrexate and aminopterin. These compounds are known to dissociate upon exposure to ultraviolet light resulting in the formation of their respective 6-formylpteridine derivatives. The relative rates of dissociation were monitored spectrophotometrically by determining the absorbance of their 2,4-dinitrophenylhydrazine derivatives at 500 nm. When aqueous solutions of folic acid, aminopterin and methotrexate were exposed to uv light, a direct correlation was observed between the concentrations of the 6-formylpteridine derivatives existing in solution and the ability of these solutions to inhibit xanthine oxidase. The relative potency of the respective photolysis products were estimated.

Aminopterin↗
PubMed1990

An evaluation of an anticoagulant clinic.

Patient comprehension of the risks of anticoagulation, tablet recognition skills and knowledge of complications of warfarin therapy were evaluated in 160 patients attending the anticoagulant clinic in a central Dublin teaching hospital group. Potential complications from over- and under- dosage with warfarin were unknown to 119 (74%) and 97 (60%) patients respectively. 1, 3 and 5 mg tablets could not be identified by 40 (25%), 55 (34%) and 60 (37%) patients respectively. The current prescribed dose could not be recollected by 31 (19%) patients. Haemorrhagic complications occurred in 23 (14%) subjects over one year, four of whom required hospital admission and two blood transfusions. No thromboembolic episodes were noted. This study reveals a widespread lack of understanding of anticoagulation and its potential complications in patients receiving warfarin therapy and has led to a critical reappraisal of patient education, patterns of referral and supervision of such individuals in our clinic.

Female↗
PubMed1990

Spice of life: a strategy to enhance dietary compliance.

A creative teaching strategy was implemented to stimulate patients' motivation to incorporate learned dietary concepts into their daily life-style. Thirty-five hemodialysis patients were given a pamphlet that described herbs and spices to enhance the flavor of specific foods and 25 sample seasoning packets for their experimentation. Most stated that the pamphlet was helpful (82.9%) and use of the spices made the diet palatable 75% or more of the time (93.4%).

Condiments↗
PubMed1990

Psychosocial aspects of Alzheimer's disease.

November is national Alzheimer's disease month. This disorder involves not only cognitive dysfunction but also psychiatric symptoms. Alzheimer's disease places a tremendous burden on caregivers. These psychosocial factors are often the causes of institutionalization.

Aged↗
PubMed1990

Heart block as a predictor of in-hospital death in both acute inferior and acute anterior myocardial infarction.

We investigated the relationship between atrioventricular block and in-hospital mortality in 705 successive patients admitted with a first Q-wave myocardial infarction of the anterior or inferior wall. Second- or third-degree atrioventricular block developed in 61 (8.6 per cent) patients and was more frequent in inferior (12.4 per cent) than anterior infarctions (4.9 per cent). A multiple logistic regression identified three factors which were independently correlated with block: inferior infarction, older age and larger infarct size as determined by cardiac enzymes. Mortality was 27.9 per cent in patients with block and 9.3 per cent in those without; it was significantly higher in both anterior (47.0 per cent vs 11.8 per cent) and inferior (20.4 per cent vs 6.7 per cent) infarction groups. When age, infarct size, infarct site and block were analysed simultaneously as predictors of death, block was a significant independent prognostic factor. The relative risk of death, corrected for age and infarct size, in patients showing block was similar for anterior and inferior infarction. Analysis of deaths revealed a higher incidence of unheralded death in inferior infarcts associated with high-degree block.

Age Factors↗