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Biomedical subjects

J M Moran

Publications and source records attributed to J M Moran.

At least 19 recordsLinked to original sources
PubMed2001

Developmental regulation of GABA(B) receptor function in rat spinal cord.

GABA(B) receptors are heterodimers coupled to G-proteins. The present study was undertaken to investigate activation of GABA(B) receptors in cerebral cortex and spinal cord using [35S]GTPgammaS binding assays, a direct measure of G-protein activity. The results revealed that the GABA(B) agonist baclofen stimulates GTPgammaS binding in cerebral cortex, with an ED50 of 50microM. This response is blocked by the GABA(B) receptor antagonist CGP 55845A (100nM). In contrast, baclofen-stimulated GTPgammaS binding was not observed in adult spinal cord tissue under similar incubation conditions, or after varying magnesium, calcium, GDP, [35S]GTPgammaS, or membrane concentrations in the assay medium. Stimulation of adult rat spinal cord muscarinic receptors did result in a concentration-related increase in [35S]GTPgammaS binding. Baclofen-stimulated GTPgammaS binding in adult spinal cord did not appear after peripheral inflammation, despite significant increases in GABA(B) subunit mRNA levels. As opposed to adult, appreciable GTPgammaS binding was observed in membranes prepared from spinal cords of rats within the first 14 days of postnatal development, suggesting that GABA(B) receptor function in the rat spinal cord is developmentally regulated. The results indicate that GABA(B) receptors may not be coupled to G-proteins in the adult rat spinal cord, or couple in a way that differs from that in newborns or adult cerebral cortex.

Age Factors↗
PubMed2001

An apparatus for applying strong longitudinal magnetic fields to clinical photon and electron beams.

Monte Carlo studies have recently renewed interest in the use of the effect of strong transverse and longitudinal magnetic fields to manipulate the dose characteristics of clinical photon and electron beams. A 3.5 T superconducting solenoidal magnet was used to evaluate the effect of a longitudinal field on both photon and electron beams. This note describes the apparatus and demonstrates some of the effects on the beam trajectory and dose distributions for measurements in a homogeneous phantom. The effects were studied using film in air and in phantoms which fit in the magnet bore. The magnetic field focused and collimated the electron beams. The converging, non-uniform field confined the beam and caused it to converge with increasing depth in the phantom. Due to the field's collecting and focusing effect, the beam flux density increased, leading to increased dose deposition near the magnetic axis, especially near the surface of the phantom. This study illustrates some benefits and challenges associated with the use of non-uniform longitudinal magnetic fields in conjunction with clinical electron and photon beams.

Electrons↗
PubMed1999

Left ventricular fibroma masquerading as postinfarction myocardial rupture.

A large left ventricular fibroma was encountered perioperatively for what was presumed to be a sealed ventricular rupture after thrombolytic therapy for an acute myocardial infarction. We review the pertinent literature concerning the diagnosis of ventricular rupture and this rare benign tumor of the heart.

Adult↗
PubMed1999

Chronic pulmonary artery balloon counterpulsation in sheep via percutaneous route.

BACKGROUND: In clinical practice pulmonary artery balloon counterpulsation (PABC) has been utilized only in the operative setting with the balloon housed in a graft attached to the pulmonary artery. Clearly, percutaneous insertion of a dedicated pulmonary artery balloon is a desirable goal for patients requiring temporary assist for right ventricular failure. METHODS: To address the question of right sided cardiopulmonary tolerance for a chronic indwelling pulmonary artery balloon, six adult ewes underwent percutaneous placement of an 11 ml pulmonary artery balloon, via the femoral vein. Effective pumping and timing were monitored for 48 hours at which time the animals were sacrificed. At autopsy gross and microscopic study of all right heart structures, the pulmonary arteries and the lungs were studied for adverse effects. RESULTS: There were inconsequential minor abrasions to right heart structures in most animals. The pulmonary artery in five of six animals revealed ecchymoses and some transmural hemorrhage, but no necrosis or perforation. There was no pulmonary injury that could not be ascribed to postoperative atelectasis. CONCLUSIONS: This study demonstrates that chronic pulmonary artery balloon counterpulsation can be carried out for a period of 48 hours without significant injury to right heart and pulmonary structures in the ovine model

Adult↗
PubMed1998

Coexisting conical bipolar and equatorial outflows from a high-mass protostar.

The BN/KL region in the Orion molecular cloud is an archetype for the study of the formation of stars much more massive than the Sun. This region contains luminous young stars and protostars but, like most star-forming regions, is difficult to study in detail because of the obscuring effects of dust and gas. Our basic expectations are shaped to some extent by the present theoretical picture of star formation, the cornerstone of which is that protostars accrete gas from rotating equatorial disks and shed angular momentum by ejecting gas in bipolar outflows. The main source of the outflow in the BN/KL region may be an object known as radio source I, which is commonly believed to be surrounded by a rotating disk of molecular material. Here we report high-resolution observations of silicon monoxide (SiO) and water maser emission from the gas surrounding source I. We show that within 60 AU of the source (about the size of the Solar System), the region is dominated by a conical bipolar outflow, rather than the expected disk. A slower outflow, close to the equatorial plane of the protostellar system, extends to radii of 1,000 AU.

Astronomical Phenomena↗
PubMed1997

Evaluation of oral hygiene products: science is true; don't be misled by the facts.

Most people in industrialized countries use oral hygiene products. When an oral health benefit is expected, it is important that sufficient scientific evidence exist to support such claims. Ideally, data should be cumulative derived from studies in vitro and in vivo. The data should be available to the profession for evaluation by publication in refereed scientific journals. Terms and phrases require clarification, and claims made by implication or derived by inference must be avoided. Similarity in products is not necessarily proof per se of efficacy. Studies in vitro and in vivo should follow the basic principles of scientific research. Studies must be ethical, avoid bias and be suitably controlled. A choice of controls will vary depending on whether an agent or a whole product is evaluated and the development stage of a formulation. Where appropriate, new products should be compared with products already available and used by the general public. Conformity with the guidelines for good clinical practice appears to be a useful way of validating studies and a valuable guide to the profession. Studies should be designed with sufficient power to detect statistically significant differences if these exist. However, consideration must be given to the clinical significance of statistically significant differences between formulations since these are not necessarily the same. Studies in vitro provide supportive data but extrapolation to clinical effect is difficult and even misleading, and such data should not stand alone as proof of efficacy of a product. Short-term studies in vivo provide useful information, particularly at the development stage. Ideally, however, products should be proved effective when used in the circumstances for which they are developed. Nevertheless, a variety of variable influence the outcome of home-use studies, and the influence of the variable cannot usually be calculated. Although rarely considered, the cost-benefit ratio of some oral hygiene products needs to be considered.

Dental Plaque↗
PubMed1997

Characteristics of scattered electron beams shaped with a multileaf collimator.

Characteristics of dual-foil scattered electron beams shaped with a multileaf collimator (MLC) (instead of an applicator system) were studied. The electron beams, with energies between 10 and 25 MeV, were produced by a racetrack microtron using a dual-foil scattering system. For a range of field sizes, depth dose curves, profiles, penumbra width, angular spread in air, and effective and virtual source positions were compared. Measurements were made when the MLC alone provided collimation and when an applicator provided collimation. Identical penumbra widths were obtained at a source-to-surface distance of 85 cm for the MLC and 110 cm for the applicator. The MLC-shaped beams had characteristics similar to other machines which use trimmers or applicators to collimate scanned or scattered electron beams. Values of the effective source position and the angular spread parameter for the MLC beams were similar to those of the dual-foil scattered beams of the Varian Clinac 2100 CD and the scanned beams of the Sagittaire linear accelerators. A model, based on Fermi-Eyges multiple scattering theory, was adapted and applied successfully to predict penumbra width as a function of collimator-surface distance.

Biophysical Phenomena↗
PubMed1996

Aortic stenosis in the elderly: result of aortic valve replacement.

Forty-six patients, 24 male and 22 females, with a mean age of 78.4 years (range 75 to 88) underwent aortic valve replacement (AVR) for severe calcific aortic stenosis during a five year period. Twenty-six patients (56.5%) had combined aortic valve replacement/coronary artery bypass (AVR/CABG) procedures. Bovine pericardial or porcine bioprostheses were used in 47.8% of cases. The mean length of stay in the intensive care unit was 2.9 days (range 2-13) with a mean hospital stay of 12.6 days (range 6-41). Operative mortality rate was 6.5% (3 patients), all in the AVR/CABG group. Complications included pneumonia (8.7%), stroke (6.5%), and complete heart block requiring pacemaker insertion (6.5%). Follow-up of survivors from 11-69 months (mean 34.6) shows 92.9% survival, with 87.2% in New York Heart Association (NYHA) Class I and II. Aortic valve replacement in the elderly population has an acceptable mortality rate and is associated with significantly improved quality of life over the intermediate term.

Aged↗
PubMed1995

Retrograde abdominal visceral perfusion: is it beneficial?

BACKGROUND: It is proposed that retrograde abdominal perfusion be used in combination with retrograde cerebral perfusion to provide total body visceral protection during aortic reconstruction; however, its physiologic effects remain unknown. METHODS: We compared the effect of superior vena caval perfusion alone with that of combined superior and inferior vena caval perfusion on the liver and kidney in 6 mongrel dogs. Organ blood flow was measured using ultrasonic flow probes on the hepatic artery, the portal vein, and the renal artery. Regional tissue blood flow to the liver and the kidney was assessed using colored microspheres and pH probes. Anesthetized dogs were placed on total cardiopulmonary bypass. After cooling to 20 degrees C, retrograde perfusion was begun with 30 minutes of superior vena caval perfusion followed by another 30 minutes of bicaval perfusion, or vice versa. RESULTS: Very little renal blood flow was measured with either method of retrograde perfusion. Although the liver received more blood flow in comparison to the kidney, there was no significant difference between superior vena caval perfusion alone and bicaval perfusion. The addition of inferior vena caval perfusion results in portal hypertension, hepatic congestion, ascites, and bowel edema. CONCLUSIONS: In the canine model, bicaval perfusion does not provide superior protection to the liver and kidneys when compared with superior vena caval perfusion alone.

Animals↗
PubMed1995

Coronary artery bypass grafting in an achondroplastic dwarf.

To our knowledge, coronary bypass for complications of coronary artery disease in achondroplasia has not previously been described. Achondroplasia, in and of itself, is not a contraindication to coronary bypass. Although the anatomic reserve of saphenous vein is less in achondroplastic dwarfs than in people of normal stature, that vessel and the internal mammary artery can be harvested in routine fashion. A 60-year-old woman with several risk factors for coronary artery disease underwent successful bypass surgery, which included the use of both a saphenous vein and the left internal mammary artery.

Achondroplasia↗
PubMed1995

A comparative study of stain removal with two electric toothbrushes and a manual brush.

Recent studies have suggested that a sonic electric toothbrush is more effective than a manual brush at removing extrinsic dental stain. There have been few studies of the comparative stain removal properties of different electric brushes. The study reported here was conducted to compare the efficacy of the sonic toothbrush (Sonicare) with an oscillating/rotating brush (Braun Oral-B Plaque Remover) and a conventional manual brush (Crest Complete). The study was a single-blind, randomized, cross-over design, balanced for residual effects and employing 24 subjects. Stain was enhanced over a 21-day period by twice-daily rinses with chlorhexidine and frequent intakes of tea and/or coffee. At the end of each period, tooth stain intensity and area, tongue stain intensity and area, lower lingual calculus and subjective tooth sensitivity were recorded together with preference for the brushes determined at the study's completion. Similar levels of tongue staining were recorded for the three periods, with no significant differences between the three groups. Tooth stain intensity, for most sites, was not significantly different between the three groups. For mean total stain area and for lingual and lingual interproximal sites, a significant reduction in stain was seen following use of the oscillating/rotating brush compared to the manual brush. The reductions in stain with the sonic brush were not significantly different from the manual brush. With the exception of maximum stain intensity, there were no significant differences between the oscillating/rotating and sonic brushes. Significantly less tooth sensitivity was found following use of the oscillating/rotating brush compared to both the manual and sonic brushes. All three brushes were found to be safe, but volunteer preference significantly and predominantly favored the oscillating/rotating brush. The results suggest that the oscillating/rotating brush is superior to a manual brush for stain removal.

Adult↗
PubMed1994

Postoperative intramyocardial abscess caused by mucormycosis.

We report the case of an intramyocardial abscess caused by mucormycosis that arose after cardiac operation. Several causes of immunosuppression in a 71-year-old woman were exacerbated after she underwent coronary revascularization. Before she died of multiple organ system dysfunction, a variety of supraventricular and ventricular arrhythmias, as well as complete heart block, developed, but the cause was not clear until autopsy revealed a large septal myocardial abscess due to mucormycosis.

Abscess↗
PubMed1992

Predictors of surgical mortality and long-term results of endocardial resection for drug-refractory ventricular tachycardia.

The results of surgical therapy performed in 51 consecutive patients with ventricular tachycardia were reviewed to determine short- and long-term predictors of success of such therapy in preventing recurrences of life-threatening ventricular arrhythmias. Of 41 patients (80%) who survived surgery, 40 had postoperative programmed stimulation and, of these patients, 78% (n = 31) had no inducible ventricular tachycardia on no antiarrhythmic therapy. This group had a very low incidence of arrhythmia recurrence, with only one nonfatal episode of ventricular tachycardia after a mean follow-up of 41 +/- 30 months. In contrast, two of the nine patients (22%) who had inducible arrhythmias postoperatively had cardiac arrest (p = 0.12). Multivariate analysis identified two significant predictors of perioperative mortality in our patients: increased duration of cardiopulmonary bypass time and increased baseline pulmonary capillary wedge pressure. It is concluded that (1) patients who do not have inducible ventricular tachycardia after arrhythmia surgery have a very low incidence of recurrent arrhythmia and (2) prolonged time of cardiopulmonary bypass and increased pulmonary capillary wedge pressure are predictive of perioperative mortality.

Adult↗