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Biomedical subjects

J E Moore

Publications and source records attributed to J E Moore.

At least 163 records · Page 9Linked to original sources
PubMed1997

Thoracotomy versus video-assisted thoracoscopic pleurectomy for spontaneous pneumothorax.

We reviewed our experience with thoracotomy (TH) and video-assisted thoracoscopic pleurectomy (VAT) for the treatment of recurrent spontaneous pneumothorax. Nine patients underwent 10 VATs. One patient had bilateral procedures 1 week apart. Nine patients underwent 10 THs. One patient had bilateral TH at the same session. The mean duration of postoperative hospital stay for VAT and TH was 5.7 days and 6.4, respectively. VAT operative time was longer (128 vs 93.6 min in the TH group); however, the estimated blood loss was larger in the TH group (136 vs 108.3 ml in the VAT group). There were no deaths in either group. In the VAT group, one patient had recurrence of pneumothorax 1 month after surgery. In the TH group, there was no recurrence of pneumothorax, but one patient had chronic pain at the site of the thoracotomy incision. One patient was lost to follow-up in each group. We conclude that VAT is a safe and reasonably effective treatment of spontaneous pneumothorax. However, large series with long-term follow-up are needed to place this procedure in its proper perspective.

Adult↗
PubMed1996

The effects of time-varying curvature on velocity profiles in a model of the coronary arteries.

Blood flow patterns in the coronary arteries are of interest due to their possible involvement in atherosclerosis localization. Spatial variations in hemodynamic flow patterns are predominantly determined by the vessel geometry. The coronary arteries represent a unique situation in the cardiovascular system because their geometry undergoes large dynamic variations during each cardiac cycle due to the contraction of the heart. This study was initiated to analyze the effects of time-varying curvature on flow velocity profiles in a curved tube model of the coronary arteries. An in vitro flow model was constructed, which consisted of a flexible curved tube through which fluid flowed under a steady imposed pressure gradient. The radius of curvature of the tube was varied in time using a stepper motor and carriage. Two different deformation configurations were used to determine if variations in center of curvature displacement affected the velocity profiles. It was found in both cases that the skewing of the axial velocity profile depended on the instantaneous dynamic vessel movement, with maximal skewing occurring when the radius of curvature was in transition from the minimum to the maximum value. The change in skewing was greater for the case where carriage moved obliquely to the main direction of flow than when the carriage moved perpendicularly. Although this study was limited to relatively low values of the radius of curvature and change in curvature, an initial understanding of this flow situation was obtained which may lead to the development of more physiologic models.

Animals↗
PubMed1996

Transvaginal versus transabdominal Doppler auscultation of fetal heart activity: a comparative study.

OBJECTIVE: Our purpose was to determine whether transvaginal Doppler auscultation is more sensitive than transabdominal auscultation for the detection of fetal heart rate in the first trimester of pregnancy. STUDY DESIGN: In a prospective study 141 patients between 6 weeks and 11 weeks 6 days of gestation underwent both transvaginal and transabdominal Doppler evaluation by use of continuous-wave Doppler instruments for detection of fetal heart rate. Transvaginal ultrasonography was used as the gold standard to establish fetal cardiac activity and to help assign gestational age. The two methods of auscultation were compared for accuracy in different gestational age ranges. Sensitivities and specificities were calculated, and associations were investigated with chi 2 analysis. The direction of disagreement between modalities was tested with the McNemar chi 2 test. RESULTS: Transvaginal auscultation outperformed transabdominal auscultation in every gestational age range. Transvaginal Doppler auscultation performed significantly better than transabdominal Doppler auscultation at 8 weeks to 8 weeks 6 days (p < or = 0.004) and 9 weeks to 9 weeks 6 days (p < or = 0.006). In pregnancies with cardiac activity, fetal heart rate can be successfully detected transvaginally in 60.5% of pregnancies at 8 weeks to 8 weeks 6 days and in 87.5% of pregnancies at 9 weeks to 9 weeks 6 days of gestation. This compares with successful transabdominal detection rates of 22.9% and 56% at 8 and 9 weeks, respectively. As gestational age advances both methods became increasingly sensitive for the detection of fetal heart rate. The earliest fetal heart rate detected transvaginally was at 6 weeks 0 days of gestation compared with 7 weeks 0 days transabdominally. The transvaginal Doppler method was also more successful in detecting the fetal heart rate in women with a retroverted uterus (p < or = 0.01). CONCLUSION: By use of continuous-wave Doppler instrumentation, transvaginal auscultation is significantly better than transabdominal auscultation in detecting fetal heart rate between 8 weeks to 8 weeks 6 days and 9 weeks to 9 weeks 6 days of gestation. Use of transvaginal auscultation has potential in the evaluation of first-trimester fetal cardiac activity.

Abdomen↗
PubMed1996

Presence of Salmonella spp. and Campylobacter spp. in shellfish.

Bivalve molluscs, (cockles, mussels, scallops and oysters) were examined according to EC shellfish bed classification regulations for faecal coliforms, Escherichia coli and salmonella, and for coliforms and campylobacter which are not specified by these regulations. Salmonella serotypes were detected in 8% of 433 molluscs. Seven salmonella isolations (2%) were made from category A beds, nominally suitable for immediate consumption according to E. coli counts. A higher percentage of salmonella isolates (6%) was detected in shellfish which require relaying or depuration prior to eating. In another survey, thermophilic Campylobacter spp. were found in 42% of 380 shellfish. These findings show bed classification on the basis of indicator organisms alone is not sufficient to assure the absence of bacterial, and no doubt viral, pathogens. Depuration and end product specifications which require the absence of salmonellae are an essential part of these regulations. Microbiologists may wish to consider whether tests for pathogens such as salmonella and campylobacter should be included when determining the suitability of shellfish for human consumption.

Campylobacter↗
PubMed1996

Calcium chelators enhance 45Ca accumulation in permeablized synaptosomes and in microsomes.

The study of intracellular Ca2+ regulation usually requires using calcium chelators to adjust [Ca2+]. We examined the effects of these chelators on calcium accumulation in microsomes and saponin-permeabilized synaptosomes to assess their influence on apparent transport properties. At a fixed free Ca2+ of 0.6 microM, increasing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N', N'-tetraacetic acid (EGTA) and total Ca2+ enhanced ATP-dependent 45Ca sequestration in synaptosomes and microsomes. The EGTA-Ca complex did not change the maximal initial calcium uptake rate or maximal steady-state accumulation. Rather, EGTA/Ca increased the apparent affinity of the microsomal transporter for Ca2+. The presence of the organic anion transport inhibitor probenicid (2.5 mM) had no effect on 45Ca accumulation in the presence of EGTA. Replacing part of the Ca2+ with Ni2+ but maintaining [Ca2+] approximately constant reduced 45Ca uptake, suggesting that the Ni-EGTA complex did not stimulate 45Ca transport. Our results imply that EGTA is not actively transported across the endoplasmic reticulum membrane, nor does the divalent ion-bound form of EGTA change the properties of the transporter. EGTA, and other mobile calcium chelators with similar structures, e.g., 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, indo 1, and fluo 3, may increase calcium uptake by delivering more Ca2+ to its transport site.

Allosteric Regulation↗
PubMed1995

Computer simulation of the propagation of contrast medium in a coronary artery during one cardiac cycle.

In some angiographic methods for measurement of mean coronary flow in ml/min, a threshold is applied to 'concentration-distance' curves obtained from a constant rate injection by computing the intravascular contrast medium concentration along the main coronary branches. If the shape of the velocity profile would remain parabolic throughout the cardiac cycle, the correct threshold value would be '50% of the concentration at the injection site'. But, coronary flow being strongly pulsatile, the shape of the velocity profile must be expected to vary appreciably within the cardiac phase. In order to investigate if a single, appropriate threshold value nevertheless exists for a great variety of coronary flow pulses and velocity profiles, the spreading of contrast medium injected continuously in a tube perfused by a time varying flow Q(t) was studied by computer simulation. While the particular time courses of flow and velocity profile appear to be of secondary importance, the ratio 'injection rate to peak coronary flow' has a major impact. If it is equal to or greater than 1, a threshold value of 47% is the best choice. If the ratio is markedly less than 1, no appropriate threshold exists and use of the 47% threshold will result in considerable flow underestimations. This was fully confirmed by measurements of absolute coronary flow performed in patients.

Blood Flow Velocity↗
PubMed1995

Genetic diversity in the non-structural gene of parvovirus B19 detected by single-stranded conformational polymorphism assay (SSCP) and partial nucleotide sequencing.

A homologous region in the parvovirus B19 non-structural gene (B19 nt 1399-1682) was examined in 50 samples from patients with a wide variety of B19-related disease from various countries by PCR amplification, single-stranded conformational polymorphism (SSCP) assay and nucleotide sequencing. Five SSCP types were confirmed by nucleotide sequence analysis. Of a total of 6 mutations, all were silent. Types 3 and 4 accounted for 92% of strains. There was no correlation between genome type and either clinical illness or patient age. However, there was a correlation between SSCP type and country of origin. Type 3 strains predominated in Japan (18/26) and the UK (6/8), whereas type 4 predominated in the USA (9/12). Notably, type 3 strains also predominated among females (14/18), whereas there were approximately equal numbers of strain types 3 (7/17) and 4 (8/17) among males; an observation which remains unexplained. Within the Japanese group, although type 3 strains predominated overall, strains isolated from 1981 to 1987 consisted of types 1 (2/15), 2 (1/15), 3 (8/15), and 4 (4/15), whereas strains isolated from 1990 to 1994 consisted almost entirely of type 3 (10/11).

Adolescent↗
PubMed1995

Investigation of a nosocomial outbreak of Pseudomonas aeruginosa pneumonia in an intensive care unit by random amplification of polymorphic DNA assay.

From July to September 1993 in the intensive care unit of the Royal Victoria Hospital there were 10 cases of pneumonia associated with sputum culture of Pseudomonas aeruginosa. The isolates had an identical biotype and pyocine typing profile. The same strain of P. aeruginosa was recovered from the sink plug-hole in two rooms, and the tap handles and ventilator tubing in a third room. All strains were retrospectively typed by the random amplification of polymorphic DNA (RAPD) method using a 26-mer oligonucleotide primer, and were identical in profile. Recommendations to medical and nursing staff included secretion isolation precautions, terminal disinfection after patient discharge, use of disposable vinyl gloves by hospital staff for all body substance contacts, thorough handwashing with 4% chlorhexidine gluconate before and after dealing with all patient contacts, and prompt, appropriate antibiotic treatment for P. aeruginosa pneumonia. RAPD is a simple and effective method to determine the relatedness of P. aeruginosa isolates, and typing results are available within a single working day; thus dramatically increasing its clinical relevance over existing molecular methods.

Bacterial Typing Techniques↗
PubMed1995

A study of the role of parvovirus B19 in rheumatoid arthritis.

Serum and synovial tissue from 26 patients with rheumatoid arthritis (RA) (according to the diagnostic criteria of the American Rheumatism Association) and 26 patients with osteoarthritis (OA) were examined. Among the RA group, the female to male ratio was 4.2:1, and the age range was 44-82 yr with a mean of 64.0 yr; joints from which synovium was sampled were hip (n = 12), knee (n = 9), ankle (n = 3) and shoulder (n = 2). The duration of rheumatoid disease ranged from 6 to 24 yr with a mean of 13.9 yr. Among the OA group, the female to male ratio was 2.25:1, and the age range was 51-88 yr with a mean of 68.2 yr; joints from which synovium was sampled were hip (n = 18) and knee (n = 8). Twenty-one patients from the RA group and 20 patients from the OA group had evidence of previous parvovirus B19 infection (serum anti-B19 IgG), and all patients from both groups were serum anti-B19 IgM negative. Synovial sections from all 52 patients were stained with mouse monoclonal antibodies, 3H8 (to B19 capsid proteins) and alpha-P (to blood group P antigen). All tissue sections examined were found to be negative for both B19 capsid proteins and blood group P antigen. Using a nested polymerase chain reaction (PCR) assay, all patients were negative for serum B19 DNA. However, B19 DNA was demonstrated in the synovium of 10 of 26 RA patients and 9 of 26 OA patients; uncorrected chi 2 value = 0.08; degrees of freedom = 1; P = 0.77. All 19 patients testing positive for synovial B19 DNA had evidence of prior exposure to B19 infection (serum anti-B19 IgG). In conclusion, although there is published evidence of chronic rheumatoid-like arthropathy following acute parvovirus B19 infection, our findings do not support the involvement of B19 in the aetiopathogenesis of RA.

Adult↗
PubMed1995

Synergistic effects of fluid shear stress and cyclic circumferential stretch on vascular endothelial cell morphology and cytoskeleton.

The development of atherosclerosis is thought to be initiated by a dysfunctional state of the vascular endothelium. The proposal that mechanical forces play a role in the localization of this disease has led researchers to develop in vitro models to assess their effects on cultured endothelial cells. The arterial endothelium is exposed simultaneously to circumferential hoop stretch and wall shear stress, yet previous investigations have focused on the isolated effects of either cyclic stretch or shear stress. The influence of physiological levels of combined shear stress and hoop stretch on the morphology and F-actin organization of bovine aortic endothelial cells was investigated. Cells subjected for 24 hours to shear stresses higher than 2 dyne/cm2 or to hoop stretch greater than 2% elongated significantly compared with unstressed controls and oriented along the direction of flow and perpendicular to the direction of stretch. Exposure to more than 4% stretch significantly enhanced the responses to shear stress. Both shear stress and hoop stretch induced formation of stress fibers that were aligned with the cells' long axes. Simultaneous exposure to both stimuli appeared to enhance stress fiber size and alignment. These results indicate that shear stress and hoop stretch synergistically induce morphological changes in endothelial cells, which suggests that circumferential strain might modulate sensitivity of endothelial cells towards shear stress.

Animals↗
PubMed1995

Parvovirus B19 infection--persistence and genetic variation.

53 patients with acute B19 infection were studied; symptoms at acute infection were rash and arthralgia (n = 26), rash (n = 7), arthralgia (n = 16), aplastic crisis (n = 3), and intrauterine fetal death (n = 1). These patients were followed for 26-85 months (mean 57 months) and re-assessed for persistent symptoms, anti-B19 antibodies, and B19 DNA. At follow-up, 7 individuals were positive for serum B19 DNA, compared with none of the controls (2-tailed p value = 0.016). All 7 of those persistently infected were women, 3 of whom had symptoms; 1 had a chronic haemolytic anaemia (initial presentation was aplastic crisis); 1 had persistent arthralgia in both knees (initial presentation was bilateral knee arthralgia); and 1 had arthralgia in one knee and chronic fatigue syndrome (initial presentation was bilateral arthralgia in knees and shoulders). For the 7 persistently infected patients, serum from the time of diagnosis of acute B19 infection was available for 4, all of which contained B19 DNA. With single-stranded conformational polymorphism (SSCP) assay of these 11 PCR products, identical SSCP types were demonstrated in 5 of 7 follow-up isolates. In 2 of the 4 cases for which both acute and follow-up PCR product was available, the SSCP type of the follow-up product was different from that of the acute product. Two B19 virus types were demonstrated in one patient (with persistent arthralgia and chronic fatigue syndrome) at follow-up assessment.

Adolescent↗
PubMed1994

Fluid wall shear stress measurements in a model of the human abdominal aorta: oscillatory behavior and relationship to atherosclerosis.

Clinically significant atherosclerosis in the human aorta is most common in the infrarenal segment. This study was initiated to test the hypothesis that flowfield properties are closely related to the localization of plaques in this segment of the arterial system. Wall shear stress was calculated from magnetic resonance velocity measurements of pulsatile flow in an anatomically accurate model of the human abdominal aorta. The wall shear stress values were compared with intimal thickening from 15 post-mortem aortas measured by quantitative morphometry of histological cross sections obtained at standard locations. Wall shear stress oscillated in direction throughout most of the infrarenal aorta, most prominently in the distal region. The time-averaged mean wall shear stress (-1.7 to 1.4 dyn/cm2) was lowest near the posterior wall in this region. These hemodynamic parameters coincided with the locations of maximal intimal thickening. Statistical correlation between oscillatory shear and intimal thickness yielded r = 0.79, P < 0.00001. Low mean shear stresses correlated nearly as well (r = -0.75, P < 0.00005). Comparison of our data with surface maps of Sudan Red staining and early lesions as reported by others revealed similar conclusions. In contrast, pulse and maximum shear stresses did not correlate with plaque localization as has been shown for other sites of selective involvement by atherosclerosis (r < 0.345). Simulated exercise conditions markedly changed the magnitude and pattern of wall shear stress in the distal abdominal aorta. These results demonstrate that in the infrarenal aorta, regions of low mean and oscillating wall shear stresses are predisposed to the development of plaque while regions of relatively high wall shear stress tend to be spared.

Adult↗
PubMed1994

Pulsatile velocity measurements in a model of the human abdominal aorta under simulated exercise and postprandial conditions.

This study examines the hemodynamics of the abdominal aorta during physiological changes in flow rates and pulse rate that occur under exercise and postprandial conditions. Hemodynamic measurements were performed using an in vitro model which took into account seven major branches, the curvature, and the pulsatile nature of blood flow of the abdominal aorta. Magnetic Resonance Imaging velocimetry employing phase-velocity encoding was used to measure the pulsatile axial velocity profiles for the entire cross-section at three axial locations. Under simulated exercise conditions, the forward velocities were approximately double those seen during rest, and the flow reversal seen for resting conditions was greatly reduced. Near the posterior wall of the infrarenal aorta, the velocities were negative for only 21 percent of the cardiac cycle as compared with 82 percent for resting conditions. Postprandial conditions produced a 25 percent reduction in peak velocity and a 33 percent reduction in mean velocity near the left anterior wall of the aorta just distal to the superior mesenteric artery (in comparison with resting conditions). The changes that can occur in abdominal aorta hemodynamics under different physiologic conditions may affect the rate of progression of atherosclerosis at this site.

Aorta, Abdominal↗
PubMed1994

Preliminary analysis of the effects of blood vessel movement on blood flow patterns in the coronary arteries.

Blood flow patterns are believed to be involved in the formation and progression of arterial diseases. It is possible that the normal physiologic movement of blood vessels during the cardiac cycle affects blood flow patterns significantly. For example, the contraction of the heart in systole and subsequent relaxation in diastole create movements of the coronary arteries, as evidenced in real-time angiography. The effects of this movement on coronary artery flow patterns have never been previously analyzed. This work was undertaken to provide a preliminary estimate of the importance of the effects of such physiologic movements on blood flow patterns in the coronary arteries. A Womersley-type solution was used to determine the effect of axial movement on the wall shear rate in a simplified model of the coronary arteries. The pulsatile pressure gradient was derived from previously published coronary artery flow waveforms. The axial movement function was obtained from a three-dimensional reconstruction of a biplanar coronary angiogram. Significant changes in wall shear rate were noted when the movement was taken into account. The maximum and minimum wall shear rates were 10 percent smaller and 107 percent larger in magnitude respectively, and the Oscillatory Shear Index (OSI) was doubled. Most of the changes in wall shear rate were observed in systole, when the pressure gradient is minimal and the movement is strongest. The results indicate that blood vessel movement during the cardiac cycle has a significant effect on hemodynamic phenomena which have been associated with the development of atherosclerosis.

Arteriosclerosis↗