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Biomedical subjects

S Kinlay

Publications and source records attributed to S Kinlay.

At least 37 records · Page 2Linked to original sources

Pathophysiology of atherosclerosis: development, regression, restenosis.

There is now a very large number of patients with coronary artery disease who have also undergone percutaneous interventions such as coronary angioplasty. Atherosclerosis and restenosis are two distinct pathologic processes with different underlying pathophysiologic mechanisms, different natural histories, different clinical presentations, and treatment strategies. Management strategies to target both processes are currently poorly applied in clinical practice. The development of integrated management strategies to target atherosclerosis, as well as restenosis in the postprocedural period remains a priority.

Arteriosclerosis↗

Treating ambulatory ischemia in coronary disease by manipulating the cell biology of atherosclerosis.

Obstructive coronary artery disease is the most common cause of morbidity and mortality in the developed world. Our understanding of the pathobiology of coronary atherosclerosis provides us with new opportunities to reduce myocardial ischemia by interventions that address these mechanisms directly. These interventions include lipid-lowering therapies that improve local coronary vasomotion, inflammation, and the procoagulant state. These interventions have also been shown to result in important reductions in clinical events, including angina pectoris, myocardial ischemia and infarction, and death. Ambulatory electrocardiography provides a versatile and quantifiable measure of regional myocardial ischemia. Reductions in ischemia, as quantified by this diagnostic modality, are associated with improved clinical outcomes that may reflect improvements in the cellular pathophysiology of coronary atherosclerosis. This review discusses new information regarding the interactions between low-density lipoprotein cholesterol, the cell biology of atherosclerosis, and the activity of ischemia in patients with coronary artery disease.

Anticholesteremic Agents↗

Where do developing World clinicians obtain evidence for practice: a case study on pneumonia.

There are few data on the practice of evidence based medicine in the developing world, nor on the actual sources of evidence that clinicians use in practice. To test the hypothesis that there was variation between and within developing countries in the proposed management of a patient with hospital acquired pneumonia, and that part of the variation can be explained by the sources of evidence used. Questionnaire responses to hypothetical case history. Investigators from 6 centres within the International Clinical Epidemiology Network (INCLEN) in China, Thailand, India, Egypt, and Kenya. Doctors chosen to represent primary and secondary hospital practice in the regions of the study centres. Investigations and initial treatments which would be ordered for a hypothetical 60-year-old woman who develops pneumonia 5 days after hospital admission, whether local data on antibiotic sensitivities are available and where information would be obtained to guide management. Chest x-ray and sputum gram stain/culture were consistently the most commonly ordered investigations, there being much greater variation in the initial treatment choices with either penicillin, a third-generation cephalosporin or aminoglycoside being the most popular choice. Textbooks were the commonest form of information source, and access to a library, textbooks and journals were statistically significantly associated with appropriate choice of investigations, but not treatment. Access to local antibiotic sensitivities was associated with appropriate initial treatment choice. Improving access to information in the literature and to local data may increase the practice of evidence-based medicine in the developing world.

Cross Infection↗

Atherogenic lipids and endothelial dysfunction: mechanisms in the genesis of ischemic syndromes.

Atherogenic lipids, particularly oxidized low-density lipoprotein, are responsible for a wide range of cellular dysfunctions within the vessel wall. The effects on endothelial cells disrupt normal control of vasomotion, with a reduction of effective nitric oxide activity, the development of a procoagulant surface, chronic low-grade inflammation, and abnormal cell growth. These changes are central not only in the development of atherosclerosis but also in the evolution of both stable and unstable ischemic syndromes. There is growing evidence that these abnormal changes in cell function respond rapidly to changes in the atherogenic lipids. Certain cell functions can improve within hours or days of cholesterol lowering.

Arteriosclerosis↗

Plasma alpha-tocopherol and coronary endothelium-dependent vasodilator function.

BACKGROUND: In the presence of atherosclerosis, the coronary endothelial vasomotor response to acetylcholine is frequently abnormal but is variable between patients. We tested the hypothesis that the plasma concentration of alpha-tocopherol is associated with the preservation of nitric oxide-mediated endothelium-dependent vasomotion. METHODS AND RESULTS: We studied 15 men and 6 women (mean age 61+/-10 years) at coronary angiography who were not taking vitamin supplements. Coronary endothelium-dependent and -independent vasomotion was assessed by intracoronary infusions of acetylcholine and nitroglycerin. The vasomotor responses were compared with the plasma concentration of alpha-tocopherol and the plasma alpha-tocopherol concentration relative to total lipid (total cholesterol plus triglycerides). The mean plasma alpha-tocopherol was 25.6+/-6.1 micromol/L, total cholesterol 193+/-27 mg/dL, triglycerides 115+/-66 mg/dL, and alpha-tocopherol to total lipid 4. 2+/-0.9 micromol. L(-1). (mmol/L)(-1). The mean vasomotor response to acetylcholine was -1% (range -33% to 28%) and to nitroglycerin 22% (range 0% to 54%). Plasma alpha-tocopherol was significantly correlated with the acetylcholine response (r=0.49, P<0.05) but not the nitroglycerin response (r=0.13, P>0.05). The acetylcholine response remained significant after adjustment for other potential sources of oxidant stress (total cholesterol, diabetes mellitus, smoking, angina class) (P<0.01). The relative concentration of alpha-tocopherol to total lipid was not related to endothelial function (r=0.24, P=0.3, n=20). CONCLUSIONS: alpha-Tocopherol may preserve endothelial vasomotor function in patients with coronary atherosclerosis. This effect may be related primarily to the action of alpha-tocopherol in the vascular wall. Further studies that assess the impact of alpha-tocopherol supplementation as therapy of endothelial dysfunction are justified.

Acetylcholine↗

Effect of lipid-lowering therapy on vasomotion and endothelial function.

The recent clinical trials of lipid lowering have established the benefit of this therapy in men and women with, or at high risk for, cardiovascular disease. It is now thought that most of the reduction in the risk of clinical events is due to functional rather than anatomic changes in atherosclerotic arteries. Cholesterol-lowering drugs improve endothelial vasomotor function and vascular nitric oxide in patients with coronary artery disease over several months. These changes in vasomotor function may reflect other beneficial changes that are regulated by nitric oxide such as the reduced recruitment and activation of inflammatory cells and a shift in the coagulation balance to favor thrombolysis. These mechanisms may contribute to the reduction in myocardial ischemia and clinical events observed with lipid lowering in patients with vascular disease. Lipid-lowering therapy decreases cardiovascular events and is an important adjunct to coronary revascularization most likely because an improvement in endothelial function prevents the development and destabilization of new atherosclerotic lesions and subsequent ischemic events.

Anticholesteremic Agents↗

Effect of transient abrupt vessel closure during otherwise successful angioplasty for unstable angina on clinical outcome at six months. Hirulog Angioplasty Study Investigators.

OBJECTIVES: The objective of this study was to identify predictors of major adverse cardiac events after successful coronary angioplasty. BACKGROUND: The acute complications of angioplasty are related to baseline clinical and angiographic variables, and early complications adversely affect long-term outcome. However, the predictors of enduring success after uncomplicated angioplasty are less well defined. METHODS: Of 4,098 patients undergoing angioplasty in the Hirulog Angioplasty Study, 3,899 (95%) had a successful procedure without in-hospital death, emergent bypass surgery or clinical evidence of myocardial infarction. Baseline and procedural variables for these 3,899 patients were examined. RESULTS: Major adverse cardiac events occurred in 22% of the patients with initially successful procedures at 6 months: death in 1%, myocardial infarction in 2% and repeat revascularization in 21%. Univariable predictors of increased events included successful salvage from abrupt vessel closure (p < 0.001), emergency stenting (p < 0.001), multilesion angioplasty (p < 0.001), diabetes (p=0.02), target lesion in the left anterior descending artery (p=0.02), unstable angina (p=0.03) and smaller final luminal diameter (p=0.04). There was a trend toward increased events among patients with prior angioplasty (p=0.08), but asymptomatic elevation of the creatine kinase was not predictive (p=0.5). In a multivariable model, abrupt vessel closure was the strongest independent predictor of major adverse cardiac events at 6 months (p < 0.001; odds ratio [95% confidence interval]=3.6 [2.5 to 5.1]), while multivessel angioplasty, target lesion in the left anterior descending artery and diabetes also remained independent predictors (all p < or = 0.02). CONCLUSIONS: This analysis suggests that "uncomplicated" abrupt vessel closure is a powerful predictor of adverse clinical outcome following successful angioplasty. Improved techniques to reduce abrupt closure during angioplasty are thus urgently needed, and patients who experience "uncomplicated" closure require closer surveillance during follow-up.

Aged↗

Chlamydia pneumoniae infection is frequent but not associated with coronary arteriosclerosis in cardiac transplant recipients.

We sought to explore the relation between Chlamydia pneumoniae, cytomegalovirus (CMV), and cardiac transplant-associated arteriosclerosis. Serologic evidence of past Chlamydia pneumoniae infection was investigated in 3 patient groups at the time of cardiac catheterization: cardiac transplant recipients (n=49), patients having coronary artery bypass grafting (CABG) (n=39), and a control group free of angiographic coronary artery disease (n=21). High Chlamydia pneumoniae immunoglobulin G titers (> or =1:160) were more frequently observed in cardiac transplant recipients (odds ratio[OR] 13.7; 95% confidence intervals [CI] 1.6 to 117.4, p <0.05) and CABG patients (OR 21.7; 95% CI 1.6 to 287.0, p <0.05) than in controls. However, high Chlamydia pneumoniae titers did not distinguish between cardiac transplant recipients with or without angiographic transplant-associated arteriosclerosis or CABG patients with or without bypass vein graft disease. Furthermore, there was no significant relation between elevated Chlamydia pneumoniae titers and the presence or progression of transplant-associated arteriosclerosis in the subgroup of patients who were also CMV positive. Yet, analysis of the same angiograms demonstrated an association between CMV infection and the recent progression of transplant-associated arteriosclerosis. Thus, patients with cardiac transplantation have evidence of past Chlamydia pneumoniae and CMV infection but Chlamydia pneumoniae does not appear to have an independent role or synergistic relation to CMV in the development of transplant-associated arteriosclerosis.

Adult↗

Incidence of mastitis in breastfeeding women during the six months after delivery: a prospective cohort study.

OBJECTIVES: To estimate the incidence of mastitis in breastfeeding women during the first six months after delivery, and to identify the healthcare services used and treatments received by women with mastitis. DESIGN: A prospective cohort study with questionnaire and telephone follow-up. SETTING: A teaching hospital and the only private hospital offering obstetrics at the time of the study in the Lower Hunter Region, New South Wales. PARTICIPANTS: 1075 women in postnatal wards following delivery of a single infant who were breastfeeding at the time of recruitment. RESULTS: 233 women returned a questionnaire indicating they believed that they had developed mastitis during follow-up. Of these, 219 had mastitis by the study criteria, giving an estimated crude incidence of 20% (95% CI, 18%-22%) in the six months after delivery. Most cases of mastitis (75%) occurred within seven weeks after delivery. Multiple episodes of mastitis were reported by 63 women: 27 reported three or more episodes during six months. 160 women (73%) reported consulting a general practitioner about their mastitis. Despite National Health and Medical Research Council guidelines that antibiotics be continued for 10 days, 148 (87%) of the 170 women who were prescribed antibiotics for the first episode of mastitis took them for less than 10 days. CONCLUSIONS: A large proportion (20%) of women who were breastfeeding developed mastitis in the six months after delivery. As general practitioners are commonly consulted about mastitis, it is important that they know how to diagnose and treat this condition.

Anti-Bacterial Agents↗

Inflammation, the endothelium, and the acute coronary syndromes.

Disruption of atherosclerotic plaques with associated thrombus is responsible for the majority of the acute coronary syndromes. Plaque instability is related closely to the degree of inflammation. Inflammatory cells within the plaque produce cytokines that inhibit collagen production by vascular smooth muscle cells and increase the production of metalloproteinases, which degrade the extracellular matrix in the fibrous cap. The recruitment of inflammatory cells into the vessel wall occurs in a coordinated sequence of events involving the expression of cellular adhesion molecules on the surface of activated endothelial cells and the production of chemoattractants, and occurs in part in response to oxidation of low-density lipoprotein within the vessel wall. The cellular adhesion molecules are shed into the circulating blood in several disease states, including clinically evident atherosclerosis. The acute-phase reactants C-reactive protein and interleukin-6, and markers of the fibrinolytic state (plasminogen activator inhibitor-1 and tissue plasminogen activator), are also elevated in the acute coronary syndromes and in healthy individuals at increased risk for developing coronary artery disease. These markers may reflect vascular inflammation and thereby the stability of atherosclerotic plaques. Their measurement may pinpoint the mechanisms of benefit of cholesterol-lowering therapy and other interventions designed to reduce coronary risk, and potentially could offer a new method for monitoring coronary risk factor reduction in patients.

Acute Disease↗

Role of endothelial dysfunction in coronary artery disease and implications for therapy.

Atherosclerosis is a complex process that is characterized by the accumulation of modified low-density lipoprotein (LDL), local inflammatory and immune responses, and reduced nitric oxide bioavailability within the arterial wall. These cellular changes lead to endothelial vasomotor dysfunction, plaque instability, and the development of clinical events such as stable angina and the acute coronary syndromes. The vascular endothelium plays a critical role in modulating both the inflammatory response and vasomotor abnormalities that occur in those with coronary artery disease or risk factors for disease. In these conditions, endothelial cells are activated by cytokines to express cellular adhesion molecules that facilitate the adhesion of leukocytes to the endothelium, and their migration into the subintimal space. Cytokines stimulate inflammatory and smooth muscle cells in the intima to produce degradative enzymes, including metalloproteinases that can weaken the fibrous cap of atherosclerotic lesions and make them vulnerable to rupture. Endothelial cells also regulate vascular tone by the synthesis of nitric oxide. Atherosclerosis and other conventional risk factors for coronary artery disease are associated with endothelial vasodilator dysfunction in the coronary epicardial and resistance vessels, which likely contributes to myocardial ischemia. Several studies have demonstrated that lowering serum total and LDL cholesterol reverses endothelial vasomotor dysfunction, reduces myocardial ischemia, and lowers the risk of the acute coronary syndromes or need for revascularization. Improving endothelial function, for example, by lowering blood cholesterol should now be regarded as a goal of therapy in the treatment of coronary artery disease.

Anticholesteremic Agents↗

Cell dysfunction in atherosclerosis and the ischemic manifestations of coronary artery disease.

Many of the cellular mechanisms and dysfunctions that underlie atherosclerotic plaque formation have been identified, including adverse interactions between atherogenic lipids and the arterial endothelium, loss of endothelium-dependent dilation, accumulation of inflammatory cells and mediators of inflammation in the intima of the arteries, and a decline in anticoagulant defenses. Several studies have shown that these mechanisms, which appear to be active throughout the pathogenesis and progression of atherosclerosis, are reversible within days, weeks, or months with effective lipid-lowering therapy. In addition, the findings of large-scale trials of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors suggest that the rapid improvement observed in trial participants is attributable to a reversal of endothelial and vascular wall dysfunctions rather than to a reduction in plaque size. The accumulated evidence indicates that improved endothelial function can benefit patients who have angina pectoris and/or are at risk for myocardial infarction. Current understanding of the cellular mechanisms of atherogenesis also suggests avenues of future research to refine treatment approaches and further improve outcomes for patients with coronary artery disease.

Animals↗

Atherogenic lipids, vascular dysfunction, and clinical signs of ischemic heart disease.

LDL is oxidized in vascular endothelial cells to a highly injurious product that results in characteristic cell dysfunction(s) in large arteries and resistance vessels. The characteristic dysfunctions (ie, loss of dilation, constriction, thrombosis, and inflammation) operate before and throughout the development of atherosclerosis and particularly during plaque rupture. Although oxidized LDL appears to induce these cell/vessel wall dysfunctions in a time- and concentration-dependent manner, Tamai and colleagues have shown that this interaction can be dynamic in that a reduction in lipids restores endothelium-dependent vasomotor function almost immediately. The same intervention (ie, lipid lowering) also appears to stabilize atheroma in the long term, improves endothelium-dependent vasomotion over months, and results in a reduction in clinical signs of risk in coronary heart disease (ie, ischemia and the need for revascularization). The above leads us to some important but unanswered questions. Can we rely on clinical measures of arterial vasomotor dysfunction to represent the other important cell dysfunctions (eg, inflammation, abnormal growth) while monitoring the response to therapeutic interventions? How can we effectively inhibit oxidation of LDL in the arterial wall, and is this useful in reversing the many cell dysfunctions and clinical sequelae of coronary atherosclerosis? What is the time course for restoration of endothelial dysfunction in the atherosclerotic epicardial coronary arteries in patients with effective lipid-lowering therapy? The intracellular responses to oxidized LDL are so numerous (loss of vasodilation, loss of anticoagulant mechanisms, abnormal inflammation, and growth) that targeting therapies to specific pathways may prove difficult. Parallel efforts in basic physiological and clinical research have resulted in remarkable progress that has improved outcomes in patients with coronary heart disease. We expect that many of the characteristic cell/vessel wall dysfunctions that result from adverse interactions with risk factors are dynamic and can be manipulated in a relatively short time frame. Treatment of atherogenic lipids with other risk factors must be further refined and may well become the cornerstone for effective management of angina, unstable syndromes, and ischemia in addition to the control of important outcomes such as myocardial infarction and coronary death.

Cholesterol, LDL↗

Identifying individuals with high fat levels and low P:S ratios, in their diets, for intensive dietary intervention.

OBJECTIVES: To assess whether simple scores from a dietary questionnaire could identify those with high dietary fat or low P:S ratio intakes, for intensive dietary intervention. DESIGN: Cross-sectional and longitudinal studies. SETTING: Community setting in the Hunter Region of New South Wales, Australia. SUBJECTS: Two random samples of adults 35-69 years from the electoral roll. In the cross-sectional study 287/322 (86%) subjects completed the diet questionnaire and a reference standard questionnaire. In the longitudinal study 546/653 (84%) of subjects completed the diet questionnaire, and had blood cholesterol measured on two occasions, 3 months apart. MAIN OUTCOME MEASURES: In the cross-sectional study, the simple scores of total fat intake (Fat Intake Score) and P:S ratio (Unsaturated Score) were compared with the daily intakes of total fat and P:S ratio obtained from the standard questionnaire. In the longitudinal study, changes in the scores were compared with changes in blood total cholesterol. RESULTS: A Fat Intake Score of greater than 125 had the best receiver operator characteristics for identifying high total fat intake (> 100 g/day: sensitivity = 67%, specificity = 70%). An Unsaturated Score of less than 0.3 had the best characteristics for identifying a low P:S ratio (< 0.5: sensitivity = 63%, specificity = 60%). Subjects who decreased Fat Intake Score by one category, had a fall in blood cholesterol of 0.14 mmol L-1 (95% confidence interval (CI) = 0.01-0.26 mmol L-1), while those decreasing by two categories decreased their blood cholesterol by 0.56 mmol L-1 (95% CI = 0.30-0.86 mmol L-1). Subjects increasing their Unsaturated Score category had a fall in blood cholesterol of 0.17 mmol L-1 (95% CI = 0.02-0.32 mmol L-1). CONCLUSION: Simple dietary scores can identify those with high fat intakes, and monitor changes related to changes in blood cholesterol levels.

Adult↗

Reproducibility of brachial ultrasonography and flow-mediated dilatation (FMD) for assessing endothelial function.

BACKGROUND: High-resolution brachial artery ultrasonography is used to study vasodilator response induced by physiologic reactive hyperaemia. We examined the reproducibility of measuring flow-mediated dilatation (FMD) on two occasions. AIMS: To determine the degree of variability of this technique in our vascular laboratory for the design of clinical research studies. METHODS: Nineteen subjects were studied on two separate occasions using an Acuson 128 ultrasound device and a 7.0 MHz linear array transducer. Reactive hyperaemia was induced in the brachial artery by inflation and release of a blood pressure cuff. Nitrate-induced dilatation was assessed in 11 of the 19 subjects. Measurements were made by two observers blinded to subject details. RESULTS: The 11 subjects given sublingual GTN during the first ultrasound study had a mean nitrate-induced dilatation of 20.7% (sd 9.6). The mean vessel diameter of 3.78 mm (sd 0.7) at rest and 3.89 mm (sd 0.7) during reactive hyperaemia yielded a mean FMD of only 3.0% (sd 2.7). The mean difference in FMD within-observers was 0.13% (sd 2.07), between-observers 0.06% (sd 2.17) and between-studies was 0.57% (sd 6.83). CONCLUSIONS: The reproducibility of FMD measured by brachial artery ultrasound was poor and likely to render the measurements inaccurate for clinical research in our hands. Between-study variation contributed the largest proportion of total study variability. We suggest that investigators using this technique conduct their own careful reproducibility studies in order to avoid the misinterpretation of 'negative' studies.

Adult↗

Low-risk febrile neutropenia in a medical oncology unit.

BACKGROUND: Febrile neutropenia occurring in patients receiving chemotherapy for solid tumours or lymphoma is usually of short duration, and therefore may have a better outcome compared to patients with acute leukaemia or patients receiving myeloablative chemotherapy. AIMS: To review retrospectively the outcomes for febrile neutropenia occurring in patients of the Medical Oncology Unit at our institution, and to identify factors associated with worse outcome, particularly prolonged admission or death. METHODS: We reviewed 102 episodes of febrile neutropenia occurring in 85 patients treated between 1992 and 1994. Demographic factors, tumour-related factors and clinical aspects of the episodes were correlated with outcome. RESULTS: The median age was 60 years (range, 18-87), with 56 (55%) episodes occurring in females. Twenty-eight (27%) episodes occurred in patients with lymphoma, with the remaining 74 (73%) occurring in patients with solid tumours. At presentation, the median absolute neutrophil count (ANC) was 0.14 x 10(9)/L with a median duration of significant neutropenia (ANC < 0.5 x 10(9)/L) of three days. The median duration of fever was two days. Twenty-nine (28%) episodes had positive cultures; of these 11 had bacteraemia. Forty-four (43%) episodes were classified as unexplained fevers. The remaining 29 episodes were associated with clinically documented infection but negative cultures. There was a high treatment success rate (81%) with first-line empirical antibiotics. Of 19 treatment failures, 13 were due to the necessity for antibiotic modification; the other six patients died from infection. Factors associated with a worse outcome (including prolonged admission and death) include: diagnosis of lymphoma; increasing number of chemotherapy courses; early onset of neutropenia; pneumonia; severe hypotension; and multiple co-morbidities. CONCLUSIONS: Febrile neutropenia in adult patients with solid tumours or lymphoma is associated with a relatively good outcome, possibly due to the short duration of neutropenia. A future prospective study to validate the risk factors identified in this study would be useful for defining patients at low risk for the adverse outcomes examined, in whom less intensive management for this condition may be possible.

Adolescent↗

Effect of wetting the mouth on aortic blood pressure just before taking sublingual nitrates.

The absorption of sublingual nitrate tablets is sometimes variable. We performed a randomized controlled trial to determine whether wetting the mouth improved the decrease in aortic systolic blood pressure (BP) from sublingual nitrate tablet or spray. The 100 patients undergoing routine diagnostic cardiac catheterization were allocated to control (no nitrate), 0.3 mg sublingual nitrate tablet, 0.4 mg sublingual nitrate spray, water + 0.3 mg sublingual nitrate tablet, or water + 0.4 mg sublingual nitrate spray. Aortic systolic and diastolic BP were recorded using a fluid-filled catheter and measured off-line blind to the treatment group. Compared with control subjects, there were significant decreases in aortic systolic BP with both nitrate preparations (tablet = -7.1 mm Hg, 95% confidence interval [CI] = -12.5 to -1.6 mm Hg; spray = -8.0 mm Hg, 95% CI = -13.4 to -2.5 mm Hg). On average, water significantly increased the fall in aortic systolic BP with nitrate tablets (-5.5 mm Hg, 95% CI = -10.9 to -0.1 mm Hg, p = 0.044) but did not significantly enhance the effect of nitrate spray (-2.8 mm Hg, 95% CI = -8.3 to 2.6 mm Hg). Water significantly increased the fall in aortic diastolic BP with tablets only (-2.9 mm Hg, 95% CI = -5.5 to -0.2), and had no significant effect on heart rate. Water had a consistently larger influence on the hemodynamic effects of nitrate tablets than on the effects of nitrate spray. Patients with a dry mouth will have an increased effect from sublingual nitrate tablets if they wet their mouth before using sublingual nitrate tablets. Water does not appear to assist in the action of sublingual spray.

Absorption↗