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Biomedical subjects

R J Gray

Publications and source records attributed to R J Gray.

At least 19 recordsLinked to original sources
PubMed1992

Directional atherectomy treatment for hemodialysis access: early results.

The Simpson atherectomy device was used to treat 12 intragraft stenoses, six complete subclavian vein occlusions, and 14 venous outflow stenoses in 24 patients undergoing hemodialysis. Patients were followed up clinically and by means of venography at approximately 1, 3, 6, 9, and 12 months after treatment. Twenty-eight atherectomy specimens were examined histologically. Twenty-six (81%) of 32 lesions were treated with initial technical success. Including technical failures, seven (58%) of 12 intragraft stenoses are angiographically patent at a mean of 5.0 months and five (50%) of 10 are clinically patent at 6 months. Three (50%) of six subclavian veins are angiographically patent at a mean of 5.6 months, and four (67%) of six are clinically patent at 6 months. Three (21%) of 14 venous outflow stenoses are angiographically patent at a mean of 5.0 months and five (38%) of 13 are clinically patent at 6 months. Histologic examination showed neointimal fibromuscular hyperplasia in 26 of 28 lesions. When 30% or less angiographic residual stenosis is used as the criterion for initial technical success, directional atherectomy appears to be effective therapy for intragraft stenoses and, with balloon angioplasty, for some catheter insertion-related subclavian occlusions. Directional atherectomy appears to have a recurrence rate for venous outflow stenoses similar to that for balloon angioplasty when the same criterion is used.

Arteriovenous Shunt, Surgical↗
PubMed1992

Combined retrograde-antegrade ureteral stent passage: salvage procedure for a ureteral leak.

The authors describe a stent placement procedure for treatment of an infected ureteral leak after failure of traditional antegrade and retrograde approaches. In this procedure, a guide wire was placed across the distal ureteral segment into a urinoma with use of cystoscopic guidance. Thereafter, an antegrade approach was used to pass a wire loop snare, capture the guide wire, and withdraw it through the proximal ureter for subsequent stent passage. This approach allowed percutaneous stabilization of a ureteral leak in a patient who would have otherwise required immediate surgical repair.

Aged↗
PubMed1991

Acyclic analogues of pyrazofurin: syntheses and antiviral evaluation.

Acyclic analogues of pyrazofurin, including 4-hydroxy-3(5)-[( 2-hydroxy-1-(hydroxymethyl)-ethoxy]methyl)-1H-pyrazole-5 (3)-carboxamide (36) and 4-hydroxy-3(5)-[(2-hydroxyethoxy)methyl]-1H-pyrazole-5(3)-carboxamide (27), that possess the side chains of ganciclovir and acyclovir, respectively, were prepared by heating methyl 4-acetoxy-1-acetyl-3-bromomethyl-1H-pyrazole-5-carboxylate (15) and sodium acetate in the requisite alcohols or, for 36, with the sodium alkoxide in dry tetrahydrofuran. These analogues have no antiviral activity, except 4-hydroxy-3(5)-[(3-hydroxypropoxy)methyl]-1H-pyrazole-5(3)-carboxamide (28), which exhibited slight activity against human cytomegalovirus.

Amides↗
PubMed1991

A comparison of two splints in the treatment of TMJ pain dysfunction syndrome. Can occlusal analysis be used to predict success of splint therapy?

Controversy surrounds the diagnosis and treatment of TMJ pain dysfunction syndrome (TMJPDS). This is also reflected in the widely divergent recommendations in splint design. A study was undertaken to examine the comparative success rates of treatment by two occlusal splints with apparently diametrically opposed modes of action and to determine whether there were any factors which could be utilised to predict the success of splint therapy. Sixty-eight TMJPDS patients were randomly distributed into one of two comparable groups and were treated solely with an occlusal splint for night time wear. One group was treated with a stabilisation splint (SS) and the other with a localised occlusal interference splint (LOIS). The success rate at review with the SS was 67.6% and with the LOIS was 80.9%. This difference was not statistically significant. Pretreatment occlusal analysis demonstrated three indicators of successful splint therapy which appeared to be independent of design. These were the absence of centric relation occlusion, the existence of non-working side interferences and an absence of ideal anterior guidance.

Chi-Square Distribution↗
PubMed1991

Morbidity and mortality after coronary artery bypass in octogenarians.

One hundred fifty seven consecutive octogenarians (mean age +/- standard deviation, 82.4 +/- 1.9 years) underwent coronary artery bypass grafting with hypothermia (mean temperature, 21.8 degrees +/- 1.8 degrees C), hyperkalemic cardioplegia, and cardiopulmonary bypass in a 9-year period. Sixty-six percent were male. Preoperatively, 115 patients (73%) were in New York Heart Association functional class IV, with the remainder being in either class III (23%) or class II (4%). Twenty percent of the patients had major complications including postoperative hemorrhage (15), sepsis (9), cerebrovascular accident (6), third-degree heart block (5), renal failure requiring dialysis (1), and pulmonary embolism (1). The 30-day or in-hospital mortality rate was 7.0%. Mean total hospital stay was 26.1 +/- 17.9 days. One-year and 5-year actuarial survival rates were 85% and 62%, respectively. Higher mortality was seen to be associated with New York Heart Association class IV, left ventricular ejection fraction less than 0.40, and lesser values for cardiac output and cardiac index. At the 6-month postoperative follow-up, 73% of the survivors reported that their general health had improved as compared with before operation. This experience demonstrates that for select octogenarians with unmanageable angina pectoris, coronary artery bypass grafting is an effective therapeutic option.

Aged↗
PubMed1991

The effects of positioning variations in transcranial radiographs of the temporomandibular joint: a laboratory study.

The relationship of the mandibular condyle to the articular fossa and eminence as seen on transcranial oblique lateral (TOL) radiographs of the temporomandibular joint is used by some clinicians as an important diagnostic sign and indicator of treatment. The literature is divided on the validity of this. The aim of this study was to consider the effects of variations in both the position of the joint and the X-ray beam orientation on the image seen on TOL radiographs. TOL radiography of a mounted block specimen of a human temporomandibular joint and associated tissues was carried out using a range of specimen rotations (+20 degrees to -20 degrees with respect to the sagittal plane) and X-ray beam angulations (20 degrees, 25 degrees, 30 degrees). Analysis of tracings of the joint images showed that most of the parameters measured varied by statistically significant amounts with changes in either specimen rotation or beam angulation. It is concluded that any convention which purports to evaluate the position of the mandibular condyle in relation to the articular fossa from TOL radiographs is invalid when the orientation of the condyle to coronal and horizontal planes is unknown.

Adult↗
PubMed1991

Valvular emergencies.

Valvular emergencies result from a wide variety of causes, including infectious, inflammatory, ischemic, traumatic, degenerative, and recently iatrogenic processes. In addition, prosthetic valves have brought new valvular emergencies that present unique challenges in diagnosis and therapy. The advent of color Doppler and TEE have provided significant enhancements to our diagnostic armamentarium. Similarly, thrombolytic therapy has also found a place in the treatment of a common prosthetic valve emergency--thrombosed mechanical valves. Because of the likelihood of serious consequences, rapid diagnosis and aggressive management of valvular emergencies are needed, but the results can be very gratifying and lead to excellent short- and long-term outcomes.

Aortic Dissection↗
PubMed1990

Soft occlusal splint therapy in the treatment of migraine and other headaches.

Fifty-seven patients suffering from migraine, tension headache or tension vascular headache were prescribed a soft occlusal splint for night-time wear. Dental, psychosocial/psychiatric and neurological data were recorded prior to commencement of therapy and at the conclusion of a 3 month treatment period. A statistically significant number of patients presenting with migraine or tension vascular headache experienced marked improvement or complete relief of headache symptoms, but most patients suffering from tension headache failed to benefit from splint therapy. A majority of patients displaying intercurrent features of craniomandibular dysfunction experienced reduction in these symptoms also. There was a statistically significant association between TMJ improvement and headache type. Prior to treatment, patients who subsequently benefited from splint therapy in terms of headache improvement had experienced significantly fewer headaches than patients who failed to respond, although headache intensity and duration were similar in both groups. It is suggested that headache type and frequency may be prognostic indicators of the likely success of dental splint therapy in treatment of headache. Nevertheless, the use of occlusal splints in the treatment of patients complaining of headache in the absence of evidence of craniomandibular dysfunction should not be embarked upon until medical examination has excluded the possibility of organic neurological disorder.

Adolescent↗
PubMed1990

Histopathological and scintigraphic features of condylar hyperplasia.

This investigation was undertaken to correlate the scintigraphic and histological features of condylar hyperplasia to identify consistent diagnostic findings. A series of 34 surgically excised condyles were examined from a 5 year period. Of these, 20 were diagnosed clinically and histologically as condylar hyperplasia. In 18 of these the presentation was one of increasing facial asymmetry. In all 20 cases there was an increased uptake of Technetium 99 as determined by gamma scintigraphy. The thickness of the fibrous articular layer, undifferentiated germinal mesenchyme layer and the hyperplastic cartilage layer were measured using an eyepiece graticule and the presence and frequency of islands of cartilage in the subchondral bone were noted. 7 patients received tetracycline hydrochloride 14 and 4 days pre-operatively in an attempt to quantify the calcification rate. An uninterrupted layer of undifferentiated germinal mesenchyme is a consistent feature of condylar hyperplasia. An increased uptake on scintigraphy is proportionally related to the thickness of the hypertrophic cartilage and not only to the presence but also the frequency of cartilage islands in the subchondral bone.

Adolescent↗
PubMed1990

Some diagnostic methods for Cox regression models through hazard smoothing.

In this paper some graphical methods are proposed for evaluating the fit of Cox regression models in survival analysis. The simplest procedure proposed is to estimate the baseline hazard separately within subgroups by applying kernel-based smoothing to standard cumulative hazard estimates. The different estimates should be the same, to within sampling variability, when the model is correct. A modification of this procedure gives a direct way of calculating smooth estimates of hazard ratios over time. A further modification gives estimates of ratios as a function of a continuous covariate and time. The methods are applied to data taken from a clinical trial of adjuvant therapy for breast cancer.

Analysis of Variance↗
PubMed1989

Tricuspid valve repair. Operative and follow-up evaluation by Doppler color flow mapping.

Severe tricuspid regurgitation may produce significant morbidity and mortality if not corrected, but commonly used methods of intraoperative assessment may be unreliable. Tricuspid regurgitation was evaluated by a new intraoperative technique, Doppler color flow mapping, in 85 patients before and after cardiopulmonary bypass. Regurgitation grade by intraoperative color Doppler mapping correlated well with right ventricular angiography (kappa value = 0.92, p less than 0.01; n = 8) and with preoperative color Doppler studies (kappa = 0.71, p less than 0.05; n = 51). The right atrial V wave correlated poorly with the severity of tricuspid regurgitation intraoperatively, both before (r = 0.30) and after (r = -0.05, p = no significant difference) cardiopulmonary bypass. Advanced (3+ or 4+) tricuspid regurgitation was found in 40% (21) of 52 patients requiring mitral valve repair or replacement. Tricuspid annuloplasty with a prosthetic ring provided a significant (greater than or equal to 2 grade) reduction in regurgitation severity in 94% (17/18; p less than 0.05). Without repair, tricuspid regurgitation decreased to a similar degree after mitral valve operations in 14% (5/36); only one of the five patients had advanced tricuspid regurgitation prepump. Fluid filling of the arrested right ventricle after the surgical procedure did not predict regurgitation severity (false negative rate 50%, 2/4; false positive rate 22%, 2/9). Regurgitation grade remained unchanged after the initial postpump study, up to 60 weeks postoperatively. In conclusion, color Doppler flow mapping provides more accurate intraoperative assessment of tricuspid regurgitation than the right atrial V wave or fluid filling of the right ventricle. This semiquantitative technique aids in the selection of patients appropriate for surgical repair of the tricuspid valve and is useful in judging the adequacy of tricuspid valve repair before chest closure. Advanced (3+ or 4+) tricuspid regurgitation is a common occurrence in patients undergoing mitral valve repair or replacement and rarely responds to conservative (nonoperative) management. Ring annuloplasty provides a highly effective and durable reduction in tricuspid regurgitation.

Adult↗
PubMed1989

A linear rank test for use when the main interest is in differences in cure rates.

For diseases with a positive probability of being cured, a family of alternatives to the null hypothesis of equality of survival distributions is introduced, which is designed to focus power against alternatives with differences in cure rates. The optimal linear rank test for this alternative is derived, and found to be substantially more efficient than the log-rank test for this alternative when cure rates are less than 50%, while there is little difference between the tests if the cure rates are 50% or greater. The simple test based on the difference of Kaplan-Meier estimates of the proportion cured is also examined, and found to be fully efficient for this alternative with no censoring, while its efficiency rapidly drops as censoring is increased. The new test is not a pure test of equality of cure rates when the data are censored, but rather is a test of equality of survival distributions that focuses power against late differences in the survival curves.

Clinical Trials as Topic↗
PubMed1988

Determinants of wound infection incidence after isolated coronary artery bypass surgery in patients randomized to receive prophylactic cefuroxime or cefazolin.

In this open-label, randomized drug study, we compared two cephalosporin prophylactic regimens, one using cefazolin and one using cefuroxime, in 100 patients having coronary bypass surgery. Additional epidemiological data were collected to identify the patient at higher risk for acquiring an infection. Patients were categorized into four groups: (1) no infection; (2) clinically determined infection without a culture or prescription of additional antibiotics; (3) clinical infection with no or negative wound culture and prescription of additional antibiotics; and (4) clinical infection with positive culture and need for additional antibiotics. Seven cefuroxime patients (13.5%) and 9 cefazolin patients (18.8%; p = 0.471) had a wound that became clinically infected (Groups 2-4). In a univariate analysis, 11 variables were statistically associated with the development of a wound infection. A logistic regression model defined 3 variables at an alpha level of 0.05 and 3 at an alpha level of 0.10 that predicted a wound infection. Patients were identified at high risk of wound infection if they had postoperative weight gain, long operative hospitalization, prolonged use of a Foley catheter, postoperative use of blood products, and operation performed by two specific surgeons. Our results indicated that closer observation of the high-risk patients and a definition of the mechanism of the infections are needed.

Cefazolin↗
PubMed1988

Use of the valvular resistance in the separation of normal and stenotic Hancock mitral valves.

Recent data suggests that the pressure-flow relationship for normal bioprosthetic mitral valves is linear. If this is correct, the valve resistance may provide a better indicator of normal mitral function than the Gorlin valve area. We compared the Gorlin valve area to the valve resistance (calculated as flow/pressure) in order to determine which better separated normal and stenotic Hancock mitral valves. Measurements were made using left atrial and left ventricular catheters in 42 patients undergoing Hancock mitral valve replacement. Patients were studied during pacing and isoproterenol infusion for a total of 141 measurements. Stenotic Hancock mitral valve hemodynamics were obtained at cardiac catheterization from eight patients who were studied at rest and during atrial pacing and from an additional eight patients culled from the literature (a total of 23 stenotic measurements). The Gorlin valve area ranged from 1.1 to 4.4 cm2 for the normally functioning Hancock valves and from 0.4 to 1.54 cm2 for the stenotic valves. Six measurements in patients with confirmed stenotic valves yielded Gorlin areas larger than the lowest area found in the normal valves and no value of the Gorlin valve area correctly classified all of the normal and the stenotic valves.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1988

Managing critically ill patients with esmolol. An ultra short-acting beta-adrenergic blocker.

Esmolol is a new intravenous beta-adrenergic blocker with an ultrashort (nine-minute) elimination half-life, which has been studied predominantly for control of supraventricular tachycardia and management of certain types of hypertension. Clinical studies indicate that the efficacy of esmolol is equivalent to that of propranolol and verapamil for control of supraventricular tachycardia and to sodium nitroferricyanide (sodium nitroprusside) for control of postoperative hypertension. Esmolol also has been shown to control heart rate and blood pressure during episodes of acute myocardial ischemia. Cardioselectivity is similar to that of metoprolol, and the ability to titrate the effect of esmolol may provide additional assurance that beta-adrenergic blockade will remain within the cardioselective range. The most commonly observed adverse effect seen in clinical trials was asymptomatic hypotension. Hypotension may be minimized by titrating to the minimum effective dose and is readily reversed within 10 to 30 minutes of discontinuing the infusion of esmolol. These unique features represent advantages of great potential merit in critical care medicine.

Adrenergic beta-Antagonists↗