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Biomedical subjects

J Boone

Publications and source records attributed to J Boone.

At least 19 recordsLinked to original sources
PubMed2006

First experience with robot-assisted thoracoscopic esophagolymphadenectomy for esophageal cancer.

BACKGROUND: Transthoracic esophagectomy with extended lymph node dissection is associated with higher morbidity rates than transhiatal esophagectomy. This morbidity rate could be reduced by the use of minimally invasive techniques. The feasibility of robot-assisted thoracoscopic esophagectomy (RTE) with mediastinal lymphadenectomy was assessed prospectively. METHODS: This study investigated 21 consecutive patients with esophageal cancer who underwent RTE using the Da Vinci robotic system. Continuity was restored with a gastric conduit and a cervical anastomosis. RESULTS: A total of 18 (86%) procedures were completed thoracoscopically. The operating time for the thoracoscopic phase was 180 min (range, 120-240 min), and the median blood loss was 400 ml (range, 150-700 ml). A median of 20 (range, 9-30) lymph nodes were retrieved. The median intensive care unit stay was 4 days (range, 1-129 days), and the hospital stay was 18 days (range, 11-182 days). Pulmonary complications occurred in 10 patients (48%), and one patient (5%) died of a tracheoneoesophageal fistula. CONCLUSIONS: In this initial experience, robot-assisted thoracoscopic esophagectomy was found to be feasible, providing an effective lymphadenectomy with low blood loss. Standardization of the technique and increased experience should reduce the complication rate, which is in the range of the rate for open transthoracic dissection.

Adenocarcinoma↗
PubMed2000

Cloned pigs produced by nuclear transfer from adult somatic cells.

Since the first report of live mammals produced by nuclear transfer from a cultured differentiated cell population in 1995 (ref. 1), successful development has been obtained in sheep, cattle, mice and goats using a variety of somatic cell types as nuclear donors. The methodology used for embryo reconstruction in each of these species is essentially similar: diploid donor nuclei have been transplanted into enucleated MII oocytes that are activated on, or after transfer. In sheep and goat pre-activated oocytes have also proved successful as cytoplast recipients. The reconstructed embryos are then cultured and selected embryos transferred to surrogate recipients for development to term. In pigs, nuclear transfer has been significantly less successful; a single piglet was reported after transfer of a blastomere nucleus from a four-cell embryo to an enucleated oocyte; however, no live offspring were obtained in studies using somatic cells such as diploid or mitotic fetal fibroblasts as nuclear donors. The development of embryos reconstructed by nuclear transfer is dependent upon a range of factors. Here we investigate some of these factors and report the successful production of cloned piglets from a cultured adult somatic cell population using a new nuclear transfer procedure.

Animals↗
PubMed1998

The Canadian Registry of Atrial Fibrillation: a noninterventional follow-up of patients after the first diagnosis of atrial fibrillation.

The Canadian Registry of Atrial Fibrillation (CARAF) is a nondirected, follow-up study of 1,086 patients who are enrolled at 6 centers across Canada at the time of initial electrocardiographically documented diagnosis of atrial fibrillation (AF). Enrollment commenced in 1991 with an intended 10-year follow-up. Comprehensive baseline data, including clinical history, laboratory, and echocardiographic variables were collected. The patients were treated by their own referring physicians and CARAF did not direct their care. Detailed follow-up was performed at 3 months, 1 year, then yearly, with echocardiograms repeated every 2 years. Several studies, which evaluated patient populations, predictors of events, and cardiac structure and functioning, have been performed and are ongoing. Thyroid function was evaluated at baseline, and, of 707 patients evaluated, only 6 patients were found to be hyperthyroid. Symptoms during AF were evaluated and a profile of the types of symptoms and the predictors of symptoms was compiled. Antiarrhythmic drug use is being followed. Sotalol and propafenone were the most commonly used medications, with the use of antiarrhythmic drugs increasing with recurrence of AF. The use of anticoagulants was assessed. The overall use of warfarin was relatively low, but its use increased dramatically with the presence of various risk factors including congestive heart failure, hypertension, and previous stroke. The one risk factor that did not result in increased use of warfarin was hypertension. Therefore, CARAF was able to identify that hypertension appears to be under-recognized and undertreated in its risk for thromboembolic events. CARAF is just now reaching maturity, with the majority of patients having > or=4 years of follow-up. Therefore, extensive investigations are currently under way that will evaluate the baseline characteristics and utilize these as predictors of recurrence of AF, progression to chronicity, and the occurrence of major events such as stroke and death. A very large cohort of patients with serial echocardiograms over 4 years will permit an understanding of the progression of structural and valvular disease. Therefore, CARAF offers a unique opportunity for comprehensive, nondirected follow-up of patients from their initial diagnosis of AF.

Atrial Fibrillation↗
PubMed1997

Exercise-induced left bundle branch block: a case report of false positive MIBI imaging and review of the literature.

Exercise-induced left bundle branch block is a relatively rare finding during exercise tolerance testing. A 36-year-old female with intermittent exercise-induced left bundle branch block, a MIBI study suggesting anterior ischemia and normal coronary arteries is reported. A review of the English and French language literature published from January 1985 to January 1996 is presented. Exercise-induced left bundle branch block has been reported in association with and without structural heart disease. Pooled mortality in the group with structural heart disease was 2.7% per year, and mortality was 0.17% per year when no structural heart disease was identified. Exercise-induced left bundle branch block has been reported to resolve with therapy. Noninvasive testing appears to have limited ability to detect or exclude coronary artery disease in this group. If a definitive cardiac diagnosis is required, strong consideration should be given to coronary angiography.

Adult↗
PubMed1996

How useful is thyroid function testing in patients with recent-onset atrial fibrillation? The Canadian Registry of Atrial Fibrillation Investigators.

BACKGROUND: Patients with recent-onset atrial fibrillation often undergo routine thyroid function screening to rule out thyroid disease as a cause of atrial fibrillation. METHODS: Patients with recent (< 3 months) onset of documented atrial fibrillation or flutter were enrolled in the Canadian Registry of Atrial Fibrillation from outpatient clinics, emergency departments, and hospital wards across Canada. Seven hundred twenty-six patients underwent baseline thyroid function screening and were assessed for presence of clinical thyroid disease. Serum thyrotropin level (TSH) was measured in 707 patients (97%), and thyroxine level (T4) in 407 patients (56%). RESULTS: A TSH level less than 0.1 mU/L was present in 5 patients (0.7%). A TSH level less than normal but more than 0.1 mU/L was present in 34 patients (4.7%). No patient had definite hypothyroidism (TSH > 20 mU/L), but 56 patients (7.7%) had an elevated TSH level that was less than 20 mU/L. During 1.7 years of follow-up, only 7 patients were found to have clinical hyperthyroidism, and 11 patients (1.5%) had hypothyroidism. Logistic regression analysis showed that palpitations (odds ratio, 4.9; 95% confidence interval, 1.7-14.0) and asymptomatic presentation (odds ratio, 5.5; 95% confidence interval, 1.9-16.2) were risk factors for low TSH level, and increasing age (odds ratio, 1.32 every 10 years; 95% confidence interval, 1.01-1.66) was a risk factor for high TSH level. The positive predictive value of palpitations and asymptomatic presentation for low TSH level were 9% and 8%, respectively. CONCLUSIONS: An abnormal TSH level is common in patients with recent-onset atrial fibrillation. However, clinical thyroid disease is uncommon. Routine TSH screening of patients who have atrial fibrillation has a low yield and may be better applied to those patients at higher risk of having undiagnosed clinical thyroid disease.

Atrial Fibrillation↗
PubMed1996

Spontaneous coronary artery dissection in young women.

Spontaneous dissection of the coronary arteries is quite rare. It is usually a catastrophic event with fatal outcome. We report two interesting cases of spontaneous dissection whose presentations exemplify the variable course the disorder may take. The first is the only report to our knowledge associated with aerobic exercise; the second is the only reported attempt at treatment with intracoronary thrombolysis.

Adolescent↗
PubMed1996

Follow-up of atrial fibrillation: The initial experience of the Canadian Registry of Atrial Fibrillation.

Previous reports of the follow-up of patients with atrial fibrillation have been confusing because of the variety of clinical presentations, heterogeneity of underlying pathology, and the initiation of follow-up at various stages of the patient's disease. The Canadian Registry of Atrial Fibrillation (CARAF) is a non-interventional, follow-up study of patients enrolled at the time of their initial diagnosis with atrial fibrillation at seven Canadian centres. At baseline, a comprehensive database recorded clinical, laboratory, and echocardiographic variables. No specific intervention was initiated and care was left to the attending physicians. Follow-up was performed at 3 months, 1 year, then annually. Echocardiograms were repeated every 2 years. Recurrence of atrial fibrillation, medical intervention, stroke, death, and other significant events have been specifically recorded. To date, 967 patients have been enrolled. Seven hundred and sixty-seven patients have been followed for 1 year, 468 for 2 years, and 217 for 3 years. Several studies have been undertaken on these patients. One study compared the variables of patients who were symptomatic with those who were asymptomatic. This study demonstrated that symptoms were more likely to occur if the patient were younger, had high blood pressure and high ventricular response during atrial fibrillation, and were female. These all achieve statistical significance and a formula was developed to predict the probability of symptoms in different subgroups of patients. Antiarrhythmic drug use was evaluated. Sotalol and propafenone were the most commonly used drugs and their use increased when atrial fibrillation was recurrent. Many patients initially received no antiarrhythmic drugs. Trends suggest that therapy is more aggressive with recurrence of the arrhythmia. The prevalence of thyroid abnormalities was investigated utilizing sensitive TSH measurements. This showed that overt hyperthyroidism is rare (1%) but laboratory abnormalities and history of thyroid dysfunction occurred more frequently, in 19% of patients. Another study evaluated antithrombotic therapy. Factors known to increase stroke risk, including congestive heart failure, previous stroke, and large left atrium all increased the use of anticoagulants. Anticoagulants were used more frequently in patients over the age of 65 and in patients with recurrent or chronic atrial fibrillation. There was concern that hypertension, shown to be a high predictor of stroke, did not result in a significant use of warfarin. Aspirin use was common in patients not placed on anticoagulants. Further studies are being undertaken with the ultimate goal to utilize baseline data to predict clinical outcomes.

Anti-Arrhythmia Agents↗
PubMed1996

Initial experience with 1.5-mm2 high impedance, steroid-eluting pacing electrodes.

UNLABELLED: In this human study, 21 atrial and 62 ventricular 1.5-mm2 unipolar steroid-eluting pacing electrodes were implanted in 64 patients. Pacing thresholds, lead impedance, and sensing measurements were measured via pacemaker telemetry within 24 hours postimplant, and at 1, 2, 3, 4, 6, 12, 24, and 52 weeks. Acute pacing impedances measured via a pacing systems analyzer were 1,039 +/- 292 (atrial) and 1,268 +/- 313 ohms (ventricular). A 10%-15% decline in the mean telemetered atrial and ventricular pacing impedances was observed at 1 week, but thereafter remained stable. Acute pacing thresholds at 0.5 ms were 0.5 +/- 0.3 V (atrial) and 0.4 +/- 0.1 V (ventricular). Filtered P and R wave amplitudes were 3.7 +/- 2.3 mV and 14.9 +/- 5.9 mV, respectively. In 21 patients, no complications related to the atrial electrode were observed. Of 62 patients with ventricular electrodes, 4 patients (6%) experienced complications and required surgical intervention. On these, causative factors included micro-dislodgment (1 patient), and perforation (1 patient). Sudden unexplained exit block occurred late (> 6 weeks) in two patients. In the remainder of patients, pacing thresholds and sensed electrogram amplitudes remained stable throughout the 52-week follow-up period. CONCLUSIONS: The present study validates that smaller surface (i.e., 1.5 mm2) steroid-eluting electrode designs offer excellent pacing and sensing performance with significantly higher pacing impedances. Although questions remain as to the cause of late exit block in two patients in this series, this relatively small surface electrode design offers promise toward achieving greater pacing efficiency and a theoretical 13%-16% (minimum) enhancement in permanent pacemaker longevity.

Administration, Topical↗
PubMed1996

Congenitally corrected transposition of the great arteries and exercise-induced ventricular tachycardia.

Congenitally corrected transposition of the great arteries (CCTGA) is an uncommon condition. Few patients survive past 50 years of age, because of associated congenital defects, systemic (morphological right) ventricular dysfunction, atrioventricular valvular insufficiency or complete heart block. A unique case is presented of exercise-induced ventricular tachycardia, which led to the diagnosis of CCTGA, without atrioventricular block or other cardiac anomalies.

Age Factors↗
PubMed1994

Efficacy of sotalol guided by programmed electrical stimulation for sustained ventricular arrhythmias secondary to coronary artery disease.

Sotalol is a class III antiarrhythmic drug with additional beta-blocker activity that has been shown to be effective in supraventricular and ventricular arrhythmias. Its long-term efficacy for ventricular arrhythmias is not as well described. Patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) who had their clinical arrhythmia inducible at baseline electrophysiologic study received sotalol 320 to 640 mg/day. Repeat programmed stimulation was performed after a minimum of 72 hours while receiving the final dose. Of 28 patients (25 men and 3 women) whose arrhythmias were inducible at baseline, 15 had their arrhythmias suppressed with sotalol. Sotalol had greater success in suppressing arrhythmias in those with VF (8 of 9, 89%) than in those with VT (7 of 19, 37%, p < 0.01). In patients with a history of coronary artery disease but no history of myocardial infarction the arrhythmia was suppressed in 7 of 8 (88%) compared with 8 of 20 (40%, p < 0.05) patients with a history of myocardial infarction. All 15 patients in whom ventricular arrhythmias were suppressed continued to take long-term sotalol, and at a follow-up of 10.3 +/- 6.4 months none has had arrhythmia recurrence. Thus, sotalol is an effective drug for the suppression of ventricular arrhythmias as judged by programmed electrical stimulation. It appears to be more effective in patients in whom the clinical arrhythmia is VF rather than VT.

Aged↗
PubMed1993

Kinetics and mechanism of DNA repair: an automated programmable apparatus for fast time-resolved studies of the repair of mammalian DNA after u.v. irradiation.

An automated apparatus, designed and constructed for use in fast time-resolved studies of mammalian DNA repair after u.v. irradiation, is described. The methodology makes use of caged DNA-break-trapping reagents, e.g. [alpha-32P]dideoxyadenosine triphosphate [see Meldrum, Shall, Trentham and Wharton (1990) Biochem J. 266, 885-890] and the apparatus incorporates excimer lasers both for the delivery of u.v. damage and for the photoactivation of the caged reagents. The design is based on a sample-changing turntable which permits the sequential irradiation and quenching of samples. A maximum of eight samples can be processed in a single experiment, the sequence of events being programmed on a microcomputer, which permits a very generalized experimental sequence. Pipettes for addition of cells, nucleotides and quenching agent are driven pneumatically. A pair of pneumatically operated platinum electrodes allows electroporation of cells for loading of negatively charged reagents prior to irradiation. The time resolution of the apparatus is dependent upon the experimental scheme used and can be very short (e.g. 1 ms) when caged reagents are used; a more usual period is 1 s for the shortest incubation.

Animals↗
PubMed1993

The impact of student goal orientation in physical education classes.

The theory of achievement motivation suggests that students whose goals are related to the mastery of a task are more likely to engage in adaptive patterns of behavior such as choosing challenging tasks and focusing on effort. Students whose goal orientations are ego-involved are more apt to avoid challenge and be unwilling to expend effort. The purpose of this study was to explore the impact that goal perspective has in physical education classes. Subjects (N = 90) were college students in beginning tennis classes. They completed a skill pretest and the Task and Ego Orientation in Sport Questionnaire (Duda, 1992). A system of contract grading was employed to yield an indication of students' selection of challenging tasks. The points earned toward the contracts were used as an indicant of in-class behavior. At the end of the semester, students completed a skill posttest and a cognitive processes questionnaire. A task-involved goal perspective was associated with the selection of more challenging tasks and positive scores on the questionnaire. Those two variables, in turn, were significant predictors of student achievement. The results suggest that goal perspective could be an important influence on students' thought and action in physical education classes.

Achievement↗
PubMed1992

Propafenone-mexiletine combination for the treatment of sustained ventricular tachycardia.

OBJECTIVES: The purpose of this study was to explore the efficacy of combined therapy with propafenone and mexiletine for control of sustained ventricular tachycardia. BACKGROUND: Combination antiarrhythmic drug therapy may enhance efficacy and lead to control of ventricular arrhythmias in some patients. Few reports have studied the combination of class IB and class IC drugs. Thus, this study was designed to investigate a combination of mexiletine and propafenone in patients with refractory ventricular tachycardia. METHODS: Sixteen patients with sustained ventricular tachycardia had their clinical arrhythmia induced by programmed stimulation. Procainamide and propafenone alone failed to prevent reinduction of tachycardia in all. Mexiletine was subsequently added to propafenone and programmed stimulation was repeated. RESULTS: With combination therapy ventricular tachycardia was noninducible in three patients (19%). A fourth who had presented with polymorphic ventricular tachycardia had slow bundle branch reentry (cycle length 500 ms) induced. In the other 12, tachycardia cycle length increased from 262 +/- 60 ms at baseline to 350 +/- 82 ms with propafenone and to 390 +/- 80 ms with propafenone plus mexiletine (p less than 0.0001 compared with baseline). Hemodynamic deterioration requiring defibrillation occurred in six patients at baseline study, in five taking propafenone and in two taking both drugs. CONCLUSIONS: The combination of propafenone and mexiletine is effective in suppressing the induction of ventricular tachycardia in some patients refractory to procainamide and propafenone alone. In those in whom ventricular tachycardia could still be induced, the rate was slower and hemodynamically tolerated.

Adult↗
PubMed1979

Comparison of interlaboratory results for blood lead with results from a definitive method.

Results reported by 113 participants in the Blood Lead Proficiency Testing Program conducted by the Center for Disease Control were compared with those obtained by the National Bureau of Standards (NBS) with a definitive methods (mass spectroscopy-isotopic dilution) for blood lead analyses. Data were compiled from the results obtained for 12 whole-blood samples containing 1.5 g of disodium EDTA per liter. Twelve separate blood samples were obtained from cattle which had been given lead nitrate orally. Lead concentrations in the samples ranged from 0.628 to 4.93 mumol/L (130-1020 micrograms/L) as determined by NBS. The methods used by laboratories were classified according to six basic groups: anodic stripping voltametry; and atomic absorption spectroscopy in which either extraction, carbon rod, graphite furnace, tantalum strip, or Delves cup was used. For results obtained in each group a linear regression analyses of laboratory values was made on the basis of NBS values. In comparison to the definitive method, most field methods for blood lead tended to overestimate the lead concentration when the actual lead concentration was less than 1.96 mumol/L (400 micrograms/L) and to underestimate the lead concentration when the actual lead concentration was greater than 2.45 mumol/L (500 micrograms/L).

Humans↗