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Biomedical subjects

A L Taylor

Publications and source records attributed to A L Taylor.

At least 37 records · Page 2Linked to original sources
PubMed1999

Epithelial P2X purinergic receptor channel expression and function.

P2X purinergic receptor (P2XR) channels bind ATP and mediate Ca(2+) influx--2 signals that stimulate secretory Cl(-) transport across epithelia. We tested the hypotheses that P2XR channels are expressed by epithelia and that P2XRs transduce extracellular ATP signals into stimulation of Cl(-) transport across epithelia. Electrophysiological data and mRNA analysis of human and mouse pulmonary epithelia and other epithelial cells indicate that multiple P2XRs are broadly expressed in these tissues and that they are active on both apical and basolateral surfaces. Because P2X-selective agonists bind multiple P2XR subtypes, and because P2X agonists stimulate Cl(-) transport across nasal mucosa of cystic fibrosis (CF) patients as well as across non-CF nasal mucosa, P2XRs may provide novel targets for extracellular nucleotide therapy of CF.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Reference centile charts for measures of disease activity, functional impairment, and metrology in ankylosing spondylitis.

OBJECTIVE: To construct reference centile charts for validated measures of disease activity, functional impairment, and metrology (the Bath Ankylosing Spondylitis Disease Activity Index [BASDAI], Bath Ankylosing Spondylitis Functional Index [BASFI], and Bath Ankylosing Spondylitis Metrology Index [BASMI]) in a population of patients with AS, and to explore the potential application of these charts in patient care and clinical research. METHODS: We collected BASDAI and BASFI data on 2,979 patients with AS from the Royal National Hospital for Rheumatic Diseases (RNHRD) database and BASMI data on 393 patients at RNHRD. Data on age, sex, and duration of AS were also obtained. Centile charts were constructed for the BASDAI, BASFI, and BASMI in both males and females, with duration of AS as the time-dependant variable. Where necessary, BASDAI, BASFI, and BASMI raw scores were transformed to ensure that the indices were normally distributed over the range of disease duration, and allowance was made for change in variability of the indices. RESULTS: Linear models were fitted to the mean and standard deviations of BASDAI, BASFI, and BASMI scores in males and females as a function of disease duration. A standard deviation score plot confirmed goodness of fit of the models, and fitted centiles were derived. Charts showing the 5th, 10th, 25th, 50th, 75th, 90th, and 95th centiles were constructed. The charts confirmed that AS remains active after 40 years' duration (mean BASDAI score 2.22 and 2.99 in males and females, respectively). The charts also demonstrated that females have greater disease activity and more functional impairment than males, despite better metrology. CONCLUSION: The use of centile reference charts for disease activity, functional impairment, and metrology in AS will allow physicians and patients to interpret index scores relative to a reference population and will provide the opportunity to assess change over time and response to therapeutic interventions, to improve definition of disease status, and to enhance patients' involvement in their care.

Aging↗
PubMed1998

Bioluminescence detection of ATP release mechanisms in epithelia.

Autocrine and paracrine release of and extracellular signaling by ATP is a ubiquitous cell biological and physiological process. Despite this knowledge, the mechanisms and physiological roles of cellular ATP release are unknown. We tested the hypothesis that epithelia release ATP under basal and stimulated conditions by using a newly designed and highly sensitive assay for bioluminescence detection of ATP released from polarized epithelial monolayers. This bioluminescence assay measures ATP released from cystic fibrosis (CF) and non-CF human epithelial monolayers in a reduced serum medium through catalysis of the luciferase-luciferin reaction, yielding a photon of light collected by a luminometer. This novel assay measures ATP released into the apical or basolateral medium surrounding epithelia. Of relevance to CF, CF epithelia fail to release ATP across the apical membrane under basal conditions. Moreover, hypotonicity is an extracellular signal that stimulates ATP release into both compartments of non-CF epithelia in a reversible manner; the response to hypotonicity is also lost in CF epithelia. The bioluminescence detection assay for ATP released from epithelia and other cells will be useful in the study of extracellular nucleotide signaling in physiological and pathophysiological paradigms. Taken together, these results suggest that extracellular ATP may be a constant regulator of epithelial cell function under basal conditions and an autocrine regulator of cell volume under hypotonic conditions, two functions that may be lost in CF and contribute to CF pathophysiology.

Adenosine Triphosphate↗
PubMed1998

Operative management of Haglund's deformity in the nonathlete: a retrospective study.

Haglund's deformity, or "pump bump," is a common cause of posterior heel pain. Management of the condition usually consists of nonoperative therapy. This study presents a retrospective study of 65 cases (53 patients), with symptomatic Haglund's deformity in nonathletes (13 male and 40 female), who presented during a 4-year period (1989-1994). Sixty-five percent (39 heels) of these patients failed to respond to nonoperative therapy for an average of 62 weeks, (range, 4-260 weeks). This group of patients went on to operative treatment. Surgical management consisted of excision of the posterior calcaneal tuberosity through a medial longitudinal incision with debridement, reattachment of the Achilles tendon using bone anchors, and 4 weeks of postoperative immobilization. Thirty-nine patients (74%) were contacted for follow-up. The average follow-up period for these patients was 155 weeks, (range, 92-335 weeks). There were 50% excellent results, 47% good results, 3% fair results (1 patient), and no poor results. The Maryland Foot Score for operated heels was an average of 67/100 preoperative and an average of 92/100 postoperative. On unoperated heels the score was an average of 81/100 at first evaluation and an average of 86/100 at final evaluation. Complications included one recurrence of painful prominence, one wound infection, and one incisional neuroma. The outcome of these cases demonstrated that in those patients who fail nonoperative treatment, surgical treatment of Haglund's deformity produces a predictably good surgical result when performed using the technique described.

Achilles Tendon↗
PubMed1994

Developing guidelines for local use: algorithms for cost-efficient outpatient management of cardiovascular disorders in a VA Medical Center.

Local use of practice guidelines requires paying close attention to the concerns of the patient within the framework of society, to the professional and educational needs of the provider, and to the realities of cost. One Veterans Affairs facility took the challenge of balancing these factors and developed their own algorithms for three cardiovascular disorders.

Algorithms↗
PubMed1994

Scleromyxoedema associated with synovitis and myopathy.

Scleromyxoedema is a rare skin disease characterized by the deposition of hyaluronic acid in the papillary dermis and often associated with the presence of a monoclonal para protein. Patients with this disorder may also have systemic manifestations. A case of a patient with biopsy proven scleromyxoedema who, in addition to the skin changes had a steroid responsive myopathy and polysynovitis is presented.

Carpal Tunnel Syndrome↗
PubMed1992

Interventricular septal rupture complicating acute myocardial infarction: from pathophysiologic features to the role of invasive and noninvasive diagnostic modalities in current management.

Rupture of the interventricular septum is a serious complication of acute myocardial infarction, accounting for 5% of deaths due to acute infarction. The septal perforation most frequently occurs during the first week after the infarction. The majority of these patients present with at least two-vessel coronary artery disease, and most cases have a total occlusion of the infarct-related artery. The degree of associated right ventricular damage is clinically important. Unpredictable hemodynamic deterioration can rapidly develop in 80% of the patients, and mortality with medical therapy alone exceeds 90%. Because the preoperative hemodynamic status of these patients appears to be a major determinant for survival, accurate diagnosis, urgent management, and early operative correction are necessary to avoid a catastrophic clinical outcome. Traditionally, diagnostic procedures included first, the insertion of a pulmonary artery catheter for recording of pressures, sequential oximetry, and calculation of the shunt's magnitude and the cardiac output followed by left ventriculography and coronary arteriography for angiographic demonstration of the shunt and the coronary anatomy. Currently, optimal utilization of color flow Doppler and two-dimensional and transesophageal echocardiography offers a significant clinical advantage and can be used to shorten the time spent on diagnosis, evaluation, and management prior to the urgent surgical repair. The elimination of time-consuming diagnostic tests can contribute to further improvement in the survival rate.

Cardiac Catheterization↗
PubMed1992

Segmental systolic responses to brief ischemia and reperfusion in the hypertrophied canine left ventricle.

OBJECTIVES AND BACKGROUND: Left ventricular hypertrophy is associated with increased mortality, increased myocardial infarct size and an increased incidence of sudden death. Although reperfusion after ischemia has been shown to result in decreased infarct size and recovery of systolic thickening, it is unknown how left ventricular hypertrophy might influence recovery of regional systolic thickening after ischemia and reperfusion. We hypothesized that left ventricular hypertrophy might attenuate or abolish the functional response to reperfusion. METHODS: Three groups of chronically instrumented, conscious dogs (dogs with left ventricular hypertrophy and hypertension; dogs with left ventricular hypertrophy and reduced blood pressure and a control group without hypertrophy and with normal blood pressure) underwent 15 min of ischemia and 24 h of reperfusion. Segmental systolic thickening was measured by sonomicrometers and myocardial segments were grouped by percent of control segmental systolic thickening retained at 15 min of ischemia (class 1 greater than or equal to 67%, class 2 from 0% to 66%, class 3 less than 0% control systolic thickening). The recovery of each class of segment was measured serially during reperfusion. Hemodynamic variables and regional myocardial blood flow were also measured. RESULTS: There were no differences among groups in recovery of segmental systolic thickening for class 1 segments. Systolic thickening in class 2 (hypokinetic) segments was significantly depressed (p less than 0.05 compared with control value) in the group with left ventricular hypertrophy and reduced blood pressure (but not in the group with hypertrophy and hypertension) during early reperfusion; systolic thickening in class 3 (dyskinetic) segments showed a similar trend in the group with hypertrophy and reduced pressure. CONCLUSIONS: Although left ventricular hypertrophy with hypertension did not attenuate the contractile response to reperfusion, hypertrophy with reduced blood pressure was associated with significantly greater depression of segmental systolic thickening early during reperfusion.

Animals↗
PubMed1992

Making the World Health Organization work: a legal framework for universal access to the conditions for health.

Improving global health conditions has been one of the most important and difficult challenges for the world community. Despite concerted efforts by international organizations, like the World Health Organization, great disparities in health conditions remain between developed and developing countries, as well as within those countries. The World Health Organization has achieved some successes through its Health for All strategy; however, it can and should encourage member nations to enact national and international laws to protect and promote the health status of their populations. A comparison to the lawmaking efforts in other areas by international organizations indicates that WHO may have the authority and the means to institutionalize efforts to improve global health conditions.

Forecasting↗
PubMed1991

Genetic control of flocculation in Escherichia coli.

Escherichia coli cells form flocs or aggregates by overproducing type 1 pili. When the pil operon is placed under the control of a tac or lac promoter-operator sequence, the bacterial cells can be induced to form flocs by adding isopropyl-beta-D-thiogalactopyranoside to the culture medium. This phenomenon of genetically induced flocculation can aid in the downstream of biological products. This paper describes the construction of two artificially controlled plasmids which cause cell flocculation. Cell aggregates 50 microns in mean diameter were obtained 1 h after the cells were induced.

Cloning, Molecular↗
PubMed1991

Aortic valve morphology influences regurgitant volume in aortic regurgitation: in vitro evaluation.

STUDY OBJECTIVE: According to the Gorlin hydraulic orifice equation, aortic regurgitation volume can be determined by the regurgitant orifice cross sectional area, diastolic filling period, mean pressure gradient between the aorta and left ventricle, and a constant relating the coefficients of contraction (Cc) and velocity (Cv). This study was performed to determine whether variation in aortic valve morphology affects regurgitant flow volume, Cc and Cv. DESIGN: Four aortic valve templates, modelled after circular, rheumatic, degenerative, and bicuspid lesions, were constructed with equal orifice cross sectional areas in two sizes, 0.2 and 0.7 cm2. These valves were studied in vitro in a flow model of aortic regurgitation, wherein aortic pressure was regulated by varying the height of a column of fluid. Flow, pressure, and velocity were measured, and the coefficient Cc and Cv were calculated from standard equations. MEASUREMENTS AND MAIN RESULTS: Regurgitant volume was assessed at diastolic filling periods of 0.5 and 1.0 s and averaged 15% greater for bicuspid and degenerative as compared to circular or rheumatic valve shapes (p = 0.0001). This difference was accentuated at the shorter diastolic filling time and higher pressure gradient, such that bicuspid lesions allowed 29% more regurgitant flow across the 0.2 cm2 orifice at fluid height of 120 cm over 0.5 s. This difference in regurgitant volume between valve shapes was due to an increased Cc for the bicuspid and degenerative valve shapes, suggesting that they are more efficient orifices than rheumatic or circular valve shapes. CONCLUSIONS: Aortic valve morphology influences regurgitant volume in aortic regurgitation. Specifically, degenerative and bicuspid orifice shapes have a higher contraction coefficient and allow more regurgitant flow than rheumatic or circular orifices at a given driving pressure and diastolic filling time.

Aortic Valve↗
PubMed1991

Left ventricular hypertrophy resulting from systemic hypertension: adaptive advantage and adverse consequences.

Left ventricular hypertrophy is the most important cardiovascular consequence of chronic systemic hypertension. While ventricular hypertrophy is an adaptive response to increased work load that preserves cardiac output, it nonetheless has adverse consequences. These include gradual systolic and diastolic dysfunction leading to congestive heart failure, an increased incidence of ventricular arrhythmias, accelerated atherosclerosis of the coronary arteries, and alterations (anatomic and physiologic) in the coronary microvasculature. Additionally, the presence of hypertension and hypertrophy increases the likelihood of poor outcome when ischemic heart disease occurs. Chronic systemic hypertension is prevalent among African Americans, who are therefore at risk for the development of left ventricular hypertrophy and the increase in mortality that accompanies the hypertrophic response.

Adaptation, Physiological↗