PubMed Health⌕ Search

Biomedical subjects

K Fox

Publications and source records attributed to K Fox.

At least 19 recordsLinked to original sources
PubMed1995

From antianginal drugs to myocardial cytoprotective agents.

The existing major classes of antianginal drugs improve quality of life in patients with coronary artery disease, but mortality in these patients remains unacceptably high. In order to limit the complications of the disease, it is vital to limit myocyte loss. Potentially, this can be achieved not only by prophylaxis, but also by protection, against ischemia. Any therapy that increases myocardial resistance to ischemia will protect against cell death and prolong the life of the myocyte, and possibly the patient. The mechanisms of cell damage during ischemia, and possible therapeutic interventions, are discussed.

Heart↗
PubMed1995

Effect of vibrissae deprivation on follicle innervation, neuropeptide synthesis in the trigeminal ganglion, and S1 barrel cortex plasticity.

Deprivation of vibrissae from an early age causes plasticity in S1 barrel cortex. This method of deprivation is most likely to induce plasticity by altering the balance of primary afferent activity from the deprived and spared vibrissae. To study whether or not induction or expression of this type of plasticity might be affected by follicle nerve injury caused by the deprivation technique, three different methods of detecting nerve injury were used: counting axon numbers in the distal follicle nerve, quantifying morphological changes in axons, and measuring neuropeptide expression in the trigeminal ganglion cells. First, nerves innervating follicles chronically deprived of vibrissae from birth had the same number of myelinated and unmyelinated axons as nerves from normally reared animals. Second, axons innervating deprived follicles showed no morphological changes in myelination or mitochondria characteristic of damaged nerves. Third, the corresponding nerve cell bodies in the trigeminal ganglion did not show upregulation of galanin or neuropeptide Y expression. In contrast, animals receiving mild injury of the follicle nerve endings (by cauterization of the follicle) showed profound changes in axonal myelination and mitochondria and increases in neuropeptide expression. These results imply that vibrissae deprivation does not act by inducing injury of the follicular nerve, suggesting that changes in the balance of follicle nerve activity are the cause of cortical plasticity. Consistent with this notion, a fourth experiment demonstrated that trimming the vibrissae induces cortical plasticity comparable to that induced by complete vibrissae removal.

Afferent Pathways↗
PubMed1995

The vicious circle of ischemic left ventricular dysfunction.

Myocardial ischemia tends to be self-propagating, and minor events such as plaque rupture can lead to the catastrophic sequelae of myocardial infarction and death. The biology of the endothelium and the cardiac myocyte is crucial to the development of these vicious circles. The abnormal responses of the endothelial cell in atherosclerosis tend to provoke and propagate ischemia, and because of the limited metabolic reserve of the myocyte, even short periods of ischemia can lead to left ventricular dysfunction and arrhythmias. This article examines the clinical implications of the disordered biology of the endothelial cell and the myocyte that is the basis for ischemic left ventricular dysfunction.

Coronary Vessels↗
PubMed1995

Potassium channel openers: clinical applications in ischemic heart disease--overview of clinical efficacy of nicorandil.

Nicorandil is a balanced arterial and venodilator that may also possess cardioprotective properties via its activation of ATP-sensitive potassium channels. It has a number of beneficial hemodynamic effects and has been shown to be effective in treating angina with similar efficacy as the currently available antianginal agents. In addition, it may have useful effects in unstable and variant angina. In this review we examine the hemodynamic effects of nicorandil and discuss the currently available data on its clinical efficacy, both in isolation and in comparison with other agents.

Angina Pectoris↗
PubMed1995

Detection of ambulatory ischaemia is not of practical clinical value in the routine management of patients with stable angina. A long-term follow-up study.

It has been reported that medically treated patients with stable angina and positive exercise test for ischaemia have an adverse 1-2 year outlook if they are shown also to have transient, and predominantly silent, ischaemic episodes detected by ambulatory ST segment monitoring during their daily activities: it has been suggested that this investigation could be used to identify patients more likely to benefit from early investigation and treatment. We assessed the long-term (up to 65 months) prognostic significance of transient ischaemic episodes during daily activities in 172 patients routinely attending cardiac outpatients with medically treated stable angina who had undergone exercise testing and 48 h of ambulatory ST segment monitoring between February 1988 and August 1989 for this purpose. A positive exercise test for ischaemia was not a prerequisite for inclusion. One hundred and four patients (60.5%) had a positive exercise test for ischaemia and 72 (42%) had transient ischaemia during daily activities (63 had both tests positive). Over a median 50-month follow-up period 54 patients suffered at least one cardiac event (primary event: cardiac death n = 7; non-fatal myocardial infarction n = 11; unstable angina n = 18; elective CABG/PTCA n = 18). Two further patients suffered non-cardiac death. Cardiac events, either objective (cardiac death or non-fatal myocardial infarction) or subjective (unstable angina or revascularisation) were no more likely to occur in those with transient ischaemia during daily life when compared with those without, at follow-up times up to 65 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

A comparison of the efficacy and tolerability of moclobemide given as a single daily dose or in three divided doses per day for the treatment of patients with a major depressive episode (DSM-III-R)

This was a prospective, double-blind, randomized, multicenter trial comparing moclobemide once daily (OD) with three times daily (TDS) dosing. The duration of the study was 6 weeks with the initial dose of moclobemide being 450 mg/day (either 450 mg in the morning or 150 mg three times daily). Placebo tablets were used to ensure that the study was double blind. After 2 weeks, the dose could be increased to 600 mg/day if tolerability was acceptable and efficacy was judged insufficient by the investigator. Patients were assessed at baseline and at days 3, 7, 14, 21, 28, and 42. Efficacy was primarily judged on the Hamilton Rating Scale for Depression (HAM-D) (17item). Patients had to score at least 17 to enter the study. Safety and tolerability were judged on reported adverse events, safety parameters, premature withdrawals, and a physicians' global tolerability rating. There were also three secondary efficacy parameters--the Hamilton Rating Scale for Anxiety, Visual Analogue Scales for pain and irritability, and physicians' Clinical Global Impression (CGI). A total of 130 evaluable patients were required to detect a difference of more than 20% (alpha = 0.05 and beta = 0.8) between groups. A total of 189 patients entered the study, and the standard analysis comprised 145 patients. The efficacies between the two dosing regimens as determined by the HAM-D score and from the CGI were found not to differ significantly. For the standard analysis population, there was a reduction in mean HAM-D of 73.8 and 72.9% for the OD and TDS groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Estimating the costs of substance abuse to the Medicaid hospital care program.

OBJECTIVES: The purpose of this study was to develop a model, using the epidemiologic tool of attributable risk, for estimating the cost of substance abuse to Medicaid. METHODS: Based on prior substance-use and morbidity research, population attributable risks for substance abuse-related diseases were calculated. (These risks measure the proportion of total disease cases attributable to smoking, drinking, and drug use.) The risks for each disease were applied to Medicaid hospital discharges and days on the 1991 National Hospital Discharge Survey that had these diseases as primary diagnoses. The cost of these substance abuse-related days were added to Medicaid hospital costs for direct treatment of substance abuse. RESULTS: More than 60 medical conditions involving 1100 diagnoses were identified, at least in part, as attributable to substance abuse. Factoring these substance abuse-related conditions into hospital costs, 1 out of 5 Medicaid hospital days, or 4 million days, were spent on substance abuse-related care in 1991. In 1994, this would account for almost $8 billion in Medicaid expenditures. CONCLUSIONS: The use of tobacco, alcohol, and drugs contributes significantly to hospital costs. To address rising costs, substance abuse treatment and prevention should be an integral part of any health care reform effort.

Alcoholism↗
PubMed1994

Electrospray tandem mass spectrometry for analysis of native muramic acid in whole bacterial cell hydrolysates.

Muramic acid is an amino sugar found in eubacterial cell walls and not elsewhere in nature. This study explored the use of electrospray tandem mass spectrometry (ESI MS/MS) in analysis of underivatized muramic acid in bacterial hydrolysates. Fungal hydrolysates were used as negative controls. The only processing used was hydrolysis in sulfuric acid followed by extraction with an organic base (N,N-dioctylmethylamine) to remove the acid prior to ESI MS/MS analysis. Compared with pure muramic acid, bacterial hydrolysates produced more complex ESI mass spectra, such that the protonated molecular ion at m/z 252 was barely detectable. In contrast, product ion spectra of m/z 252 were identical among pure muramic acid, Gram positive bacteria, and Gram negative bacteria. However, no characteristic product ion spectrum was manifested from m/z 252 in fungal samples. This allowed ready, visual differentiation of bacteria and fungi. Multiple reaction monitoring (MRM) following muramic acid fragmentations (m/z 252-->144 and m/z 252-->126) increased sensitivity and allowed quantitative differentiation when compared with the MRM of the internal standard N-methyl-D-glucamine (m/z 196-->44). ESI MS/MS required minimal sample preparation and allowed rapid sample throughput for analysis of muramic acid in whole bacterial cell hydrolysates.

Cell Wall↗
PubMed1994

Kinetics of bioconcentration and clearance of 28 polychlorinated biphenyl congeners in zebrafish (Brachydanio rerio).

Bioconcentration experiments were performed on 28 polychlorinated biphenyl (PCB) congeners with NCl = 2 to NCl = 10, evaluating them simultaneously. Bioconcentration factors (BCFs) were calculated from the uptake rate constant (k1) and the clearance rate constant (k2) as BCF = k1/k2. BCFs on a wet weight basis ranged from 7710 to 940,000. They were correlated with octanol-water partition coefficients (P). The curvilinear relationship between log BCF and log P based upon data covering the log P range 5.06 to 8.18. About a log P of 7.38, a range of "optimal lipophilicity," results in highest BCFs for PCBs, above which the degree of bioconcentration decreases.

Animals↗
PubMed1994

Nitrates in silent ischemia.

In recent years it has become clear that episodes of transient myocardial ischemia commonly occur in patients with coronary artery disease in the absence of chest pain or angina equivalent. These episodes of "silent myocardial ischemia" are particularly well documented during continuous ambulatory electrocardiographic monitoring in daily life. Evidence suggests that these episodes represent true ischemia, and appear to be a marker of unfavorable outcome. While the pathophysiology is not completely understood, it appears as though the mechanisms of angina and silent ischemia are the same. Both forms of ischemia respond to conventional antianginal medication. While long-acting nitrates are effective in reducing or preventing myocardial ischemia, because of their propensity to cause tolerance they should be used intermittently and in association with either beta-blockers or calcium antagonists. Nitrates are safe and comparatively inexpensive, and will continue to play an important role in the treatment and prevention of angina. However, in the light of current knowledge, there is no specific indication for the treatment of silent ischemia by nitrates.

Administration, Cutaneous↗
PubMed1994

Gender differences in adult health: an international comparison.

This article uses data from the United States, Jamaica, Malaysia, and Bangladesh to explore gender differences in adult health. The results show that women fare worse than men across a variety of self-reported health measures in all four countries studies. These health status disparities between men and women persist even after appropriate corrections are made for the impact of (a) differential mortality selection by gender and (b) sociodemographic factors. Data from Jamaica indicate that gender disparities in adult health arise early and persist throughout the life cycle, with different age profiles for different measures.

Adolescent↗
PubMed1994

The effects of intracoronary substance P and acetylcholine on coronary blood flow in patients with idiopathic dilated cardiomyopathy.

Attenuation of the increase in blood flow caused by acetylcholine in the peripheral vasculature and coronary circulation of patients with heart failure has been interpreted as an impairment of endothelium-dependent vasodilation. The aim of this study was to compare in man the effects of acetylcholine, which also has endothelium-independent actions, with substance P, which appears to be a pure endothelium-dependent vasodilator, on epicardial and resistance coronary arteries in patients with idiopathic dilated cardiomyopathy. The effects of intracoronary acetylcholine (10(-7) M and 10(-6) M) and substance P (5, 10 and 25 pmol.min-1) on epicardial coronary artery diameter and coronary blood flow velocity were measured with an intracoronary Doppler flow probe and quantitative coronary angiography in 11 patients with idiopathic dilated cardiomyopathy and 10 control subjects. Epicardial coronary artery diameter did not change with acetylcholine but increased significantly with substance P in both groups (cardiomyopathy patients: 3.3 +/- 0.2 mm (mean +/- SEM) at baseline vs 3.9 +/- 0.2 mm with substance P25 pmol.min-1, P < 0.01; controls: 3.1 +/- 0.2 mm at baseline vs 3.9 +/- 0.3 mm with substance P25 pmol.min-1, P < 0.05). Coronary flow ratios with acetylcholine were lower in cardiomyopathy patients (10(-7) M: 1.4 +/- 0.1 vs 2.3 +/- 0.4, P = 0.05; 10(-6) M: 1.8 +/- 0.2 vs 3.2 +/- 0.5, P = 0.05 vs controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Serum lactogens possessed normal bioactivity in patients with lactation insufficiency.

OBJECTIVE: Insufficient breast milk is the most common reason for premature termination of breast-feeding. The causes of lactation insufficiency are usually multifactorial; in a small percentage of cases it is due to primary lactation failure of unknown origin. The aim of this study was to investigate whether lactation insufficiency of unknown origin could be caused by serum lactogens that had reduced biological activity. DESIGN: Women with lactation insufficiency of unknown origin and normal lactating controls were subjected to a standardized breast-feeding test for assessment of milk production. Thirty minutes later, serum samples were obtained for determination of total lactogen bioactivity, using an in-vitro bioassay, and levels of prolactin (PRL) and growth hormone (GH) using radioimmunoassay (RIA). PATIENTS: Twelve lactating mothers with a clinical diagnosis of lactation insufficiency of unknown origin were compared with 12 matched mothers with normal lactation. MEASUREMENTS: The Nb2 lymphoma cell bioassay was used to measure total lactogen bioactivity in sera. Conventional RIA kits were used to estimate serum PRL and GH concentrations. RESULTS: Mean milk yield on standardized test feed was 21.6 ml for patients and 146.5 ml for controls. In both patient and control groups the total serum lactogen bioactivity ranged from about 150 to 5000 mIU/l, while the serum RIA (PRL+GH) levels ranged from about 350 to over 7000 mIU/l. There was no evidence of lactogens with reduced bioactivity in the patients' sera. CONCLUSION: Lactation insufficiency in the women studied cannot be explained by serum lactogens that possess unusually low bioactivity.

Biological Assay↗
PubMed1994

Perceived locus of causality, goal orientations, and perceived competence in school physical education classes.

Ryan & Connell (1989) have demonstrated that different types of behavioural regulation can be located on a continuum of perceived autonomy or perceived locus of causality. The present study applied their formulation in the context of school physical education (PE) and examined the relationships of perceived autonomy, perceived competence and goal orientations with intrinsic interest across two PE activities. School students aged 12-14 years (N = 85) completed an adapted version of the Self-Regulation Questionnaire (Ryan & Connell, 1989) and measures of perceived competence and intrinsic interest separately for two PE activities. They also completed the British version of the Task and Ego Orientation in Sport Questionnaire (Duda, Fox, Biddle & Armstrong, 1992). Students appeared to be differentially motivated for the two activities due to different perceptions of autonomy. Structural equation modelling analysis showed that perceived autonomy and task orientation had direct effects on intrinsic interest for both the activities. Perceived competence, however, was positively associated with intrinsic interest only for one of the activities. The implications of the results for the practice of physical education are discussed.

Achievement↗
PubMed1993

Do NMDA receptors have a critical function in visual cortical plasticity?

The theoretical framework, by which we understand the function of NMDA receptors, is derived, in large part, from work conducted on the hippocampal slice preparation, where NMDA receptors are crucial for a form of synaptic plasticity known as long-term potentiation (LTP). Establishing their role in plasticity mechanisms in the neocortex is proving to be far more difficult than originally envisaged, in part due to the fact that the operation of NMDA receptors is different in the intact animal than in vitro. For example, NMDA receptors are activated at low levels of sensory input in intact animals but only by high levels of input in slice preparations. Recent results suggest that a re-evaluation of the role of NMDA receptors in neocortical plasticity is required. Here we discuss some of the issues and introduce four criteria by which any factor supposedly involved in plasticity can be judged. NMDA receptors fulfill more of these criteria than any of the other factors so far investigated in the visual cortex, but maybe this is because they have been studied more intensively.

Animals↗