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Biomedical subjects

W A Gray

Publications and source records attributed to W A Gray.

At least 19 recordsLinked to original sources
PubMed2005

Endovascular treatment of extra-cranial carotid artery bifurcation disease.

Over the past decade, carotid stenting with embolic protection has emerged as a viable alternative to carotid endarterectomy in patients with severe extra-cranial bifurcation atherosclerotic disease. Several patient subsets -- high surgical risk, symptomatic, asymptomatic, etc.,-- have and are being studied in multi-center trials throughout Europe and the United States. Results of trials to date suggest that, in the high surgical risk cohorts, carotid stenting is statistically on par with endarterectomy with strong trends toward superiority in at least 2 trials SAPPHIRE and ARCHeR. In addition to these important ongoing clinical studies, physician training, reimbursement, and registry development still are in the early stages of evolution in the US.

Carotid Stenosis↗
PubMed2000

Safety, efficacy, and durability of carotid artery stenting for restenosis following carotid endarterectomy: a multicenter study.

PURPOSE: To present the results of a multicenter registry established to collect data on carotid stent procedures in patients with restenosis following carotid endarterectomy. METHODS: The procedural details, outcomes, and late follow-up results were collected from 14 centers in the United States. Thirty-day and late stroke and death rates were analyzed. RESULTS: Three hundred and thirty-eight patients (201 men; 71 +/- 8 years) underwent carotid stenting in 358 arteries. The average duration from carotid endarterectomy was 5.5 +/- 7.3 years. Sixty-one percent of the patients were asymptomatic. The overall 30-day stroke and death rate was 3.7%. The minor stroke rate was 1.7% (6/358), and the major nonfatal stroke rate was 0.8% (3/358). The fatal stroke rate was 0.3% (1/358), and the nonstroke-related death rate was 0.9% (3/338). There was 1 (0.3%) fatal and 1 (0.3%) nonfatal stroke during the follow-up period. The overall 3-year rate of freedom from all fatal and nonfatal strokes was 96% +/- 1% (+/- SE). CONCLUSIONS: Carotid artery stenting can be performed in patients with restenosis following carotid endarterectomy with 30-day complication rates comparable to those of most published studies on repeat carotid endarterectomy. Results of late follow-up suggest that this technique is durable and efficacious.

Aged↗
PubMed1999

Ultra-fast track hospital discharge using conventional cardiac surgical techniques.

BACKGROUND: Recent introduction of minimally invasive adult cardiac surgical techniques has emphasized the advantage of early hospital discharge. However, we chose an alternative approach to determine the safety, efficacy, and feasibility of ultra-fast track protocols while retaining both standard surgical exposure (median sternotomy) and conventional cardiac surgical techniques (hypothermia, cardiopulmonary bypass with cardiac arrest, and optimal myocardial protection). METHODS: From September 1995 to January 1998, a total of 258 consecutive patients underwent cardiac procedures by a single surgeon. Acceleration of clinical pathways was used to initiate earlier discharges. Stringent postdischarge follow-up was implemented. Prospectively entered data were then analyzed retrospectively. RESULTS: A variety of isolated as well as combined coronary and valve procedures were performed. Of the 258 patients operated on during this entire study period, a total of 144 patients (56%) were discharged within postoperative days 1 to 4 (ultra-fast track discharge). Over the past 12 months, this incidence increased to 70% (76 of 108 patients). Approximately 50% of these patients were operated on urgently or emergently. To date, there have been no deaths in this ultra-fast track group. There were eight brief readmissions, of which one was for rewiring of a noninfected sternal dehiscence, and the remaining were for cardiac diagnostic studies or a noncardiac problem altogether. CONCLUSIONS: Conventional cardiac operation can allow ultrafast hospital discharges while retaining the advantage of time-tested techniques and providing wider application without requiring new or additional training or equipment.

Adult↗
PubMed1991

Unsuccessful emergency medical resuscitation--are continued efforts in the emergency department justified?

BACKGROUND: The majority of attempts to resuscitate victims of prehospital cardiopulmonary arrest are unsuccessful, and patients are frequently transported to the emergency department for further resuscitation efforts. We evaluated the efficacy and costs of continued hospital resuscitation for patients in whom resuscitation efforts outside the hospital have failed. METHODS: We reviewed the records of 185 patients presenting to our emergency department after an initially unsuccessful, but ongoing, resuscitation for a prehospital arrest (cardiac, respiratory, or both) by an emergency medical team. Prehospital and hospital characteristics of treatment for the arrest were identified, and the patients' outcomes in the emergency room were ascertained. The hospital course and the hospital costs for the patients who were revived were determined. RESULTS: Over a 19-month period, only 16 of the 185 patients (9 percent) were successfully resuscitated in the emergency department and admitted to the hospital. A shorter duration of prehospital resuscitation was the only characteristic of the resuscitation associated with an improved outcome in the emergency department. No patient survived until hospital discharge, and all but one were comatose throughout hospitalization. The mean stay in the hospital was 12.6 days (range, 1 to 132), with an average of 2.3 days (range, 1 to 11) in an intensive care unit. The total hospital cost for the 16 patients admitted was $180,908 (range per patient, $1,984 to $95,144). CONCLUSIONS: In general, continued resuscitation efforts in the emergency department for victims of cardiopulmonary arrest in whom prehospital resuscitation has failed are not worthwhile, and they consume precious institutional and economic resources without gain.

Cardiopulmonary Resuscitation↗
PubMed1991

Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis.

BACKGROUND: This study tested the hypotheses in the setting of a coronary artery stenosis that 1) planar 99mTc-teboroxime myocardial scans are capable of providing a good estimate of relative coronary flow reserve, and 2) delayed washout of the tracer from the myocardium is a marker of reduced myocardial blood flow and, in certain cases, myocardial ischemia. METHODS AND RESULTS: Experiments were conducted in eight closed-chest domestic swine prepared with an artificial stenosis that reduced diameter of the left anterior descending coronary artery by 80%. Measurements of hemodynamics, regional myocardial blood flow, oxygen, and lactate metabolism were made 1) at baseline, 2) after 5 minutes of intravenous infusion of adenosine and neosynephrine ("stress"), and 3) at recovery 2 hours after discontinuing the adenosine/neosynephrine infusion. Simultaneous intravenous injection of teboroxime (approximately 9 mCi) and thallium (approximately 3.5 mCi) was made at peak stress, and serial planar teboroxime imaging began 1-2 minutes later. Scans were made in dynamic mode for 30 seconds each for 7 minutes after which a stress thallium scan (7 minutes acquisition) was obtained. A redistribution thallium scan was made 2 hours later after which a repeat teboroxime injection followed by serial imaging for 7 minutes was performed. The animal was then killed, and the heart removed for determination of microsphere activity. Under baseline conditions, transmural myocardial blood flow (ml/min/g) distal to the stenosis (1.06 +/- 0.17) was reduced (p less than 0.01) compared with the normally perfused circumflex zone (1.50 +/- 0.31). In response to intravenous infusion of adenosine/neosynephrine, flow increased (p less than 0.01) compared with baseline in both distal (2.00 +/- 0.84) and circumflex (4.67 +/- 1.55) zones. However, the distal : circumflex flow declined (0.45 +/- 0.17) compared with baseline (0.73 +/- 0.17; p less than 0.01). Two hours later flow had returned to baseline levels in both zones, and lactate production during stress (-41.7 +/- 37.5 mumol/min/100 g) had reverted to consumption (13.6 +/- 7.7; p less than 0.05). Analysis of stress teboroxime scans demonstrated 1) an increase (p less than 0.01) in the ischemic : normal zone (IZ:NZ) count between 30-second (0.50 +/- 0.14) and 7-minute scans (0.61 +/- 0.11); 2) a good correlation between the 30-second scan IZ:NZ count and the stress distal : circumflex flow (0.45 +/- 0.17; r = 0.74; p less than 0.05; slope = 0.90; intercept = 0); and 3) a close correlation between the IZ:NZ count of the 7-minute scan (0.61 +/- 0.11) and the recovery distal : circumflex flow (0.69 +/- 0.21; r = 0.89; p less than 0.01). The IZ:NZ count also increased (p less than 0.01) between 30-second (0.65 +/- 0.15) and 7-minute (0.72 +/- 0.14) scans following rest injection of teboroxime. As anticipated, serial thallium scans demonstrated evidence of redistribution between stress (IZ:NZ count = 0.62 +/- 0.08) and recovery (IZ:NZ count = 0.75 +/- 0.06; p less than 0.01) time points. The stress thallium scan IZ:NZ, however, was greater than that of the 30-second teboroxime scan as well as that of the stress distal : circumflex flow. CONCLUSIONS: Accordingly, the data indicate that 1) myocardial imaging with 99mTc-teboroxime is valuable in the noninvasive assessment of relative coronary flow reserve and that 2) delayed washout of the tracer from the myocardium reflects reduced myocardial blood flow and, under conditions comparable to those of the present study, may be a marker of myocardial ischemia.

Animals↗
PubMed1985

Specificity of monoclonal antibodies reactive with Fusobacterium nucleatum: effect of formalin fixation.

Monoclonal antibody specific for Fusobacterium nucleatum was reacted with untreated and formalin fixed F. nucleatum cells by an enzyme-linked immunosorbent assay (ELISA) and by indirect immunofluorescence. Treatment of bacterial cells with formalin destroyed the antigenic determinant responsible for reactivity with this monoclonal antibody in both assays. Formalin fixation had no effect on hemagglutination activity (HA) of F. nucleatum cells or reactivity with polyvalent rabbit antiserum in double diffusion in agar. Scanning electron microscopy demonstrated that formalin fixation did not affect binding of F. nucleatum cells to microtiter plates. When developing monoclonal antibodies to be used as diagnostic reagents, the antigenic form utilized for immunization should be identical to the antigenic form which will eventually be used in the diagnostic assay.

Animals↗
PubMed1977

The electron microscopy of bacteriophage-like particles in dental plaque.

The morphology of bacteriophage-like particles contained in samples of dental plaque is described. The phage-like particles were observed within fusiform-shaped bacteria and in clumps between bacteria. The particles were hexagonal in cross section, approximately 1,100 nm in diameter and contained an electron-dense core. In areas of cell lysis tail forms were observed both free and in association with the particles. Occasional particles were attached to bacterial cell walls by means of shortened tailpieces.

Bacteria↗
PubMed1975

Effect of water and mouthwashes on pH of oral monkey mucosa.

Among the many factors involved in homeostasis, maintenance of hydrogen-ion concentration is one of the most important functions of the body. Surface pH measurements of oral tissues after rinsing with water or mouthwashes are meager. This report presents results of the effect of tap water and 9 commercial mouthwashes on intraoral pH under controlled conditions. Nine rhesus monkeys, 5 females and 4 males between 3 and 8 years of age, were used in this study. During measurements they were sedated with phencyclidine hydrochloride and anesthetized with pentobarbital sodium. A Beckman pH meter with potassium chloride and silver chloride combination electrode was utilized. The pH was measured on the lingual gingva opposite the right lower first molar. Control readings were obtained, then a 30-sec pulsed-water-jet lavage with tap water with a force of 5 psi was given, and the pH was observed for 5 min. The 1 ml of mouthwash was administered on a thoroughly soaked gauze for 30 sec. This procedure was repeated 3 times on different days for each of the 9 mouthwashes used. All of the measurements showed a decrease in pH after tap-water lavage. In general, acid mouthwashes decreased the pH, while mouthwashes with alkaline pH's increased the pH of the oral tissues. The effects on pH was, however, transitory since the major change appeared within 8 min and approached equilibrium by 12 to 16 min.

Animals↗