Evaluation of genome similarities using the non-decimated wavelet transform.

The wavelets have become increasingly popular in the field of bioinformatics due to their capacity in multiresolution analysis and space-frequency localization; the latter particularity is acquired due to a moving window that runs through the analyzed space. As a feature, they have a better ability to capture hidden components of biological data and an efficient link between biological systems and the mathematical objects used to describe them. The decomposition of signals/sequences at different levels of resolution allows obtaining distinct characteristics in each level. The energy (variance) obtained at each level provides a new set of information that can be used to search similarities between sequences. We show that the behavior of GC-content sequence can be succinctly described regarding the non-decimated wavelet transform, and we indicate how this characterization can be used to improve clustering of the similar strains of the genome of the Mycobacterium tuberculosis, having a very efficient level of detail. The clustering analysis using the energy obtained at each level of the analyzed sequences was essential to verify the dissimilarity of the sequences.

Bayesian forecasting of temporal gene expression by using an autoregressive panel data approach.

We propose and evaluate a novel approach for forecasting gene expression over non-observed times in longitudinal trials under a Bayesian viewpoint. One of the aims is to cluster genes that share similar expression patterns over time and then use this similarity to predict relative expression at time points of interest. Expression values of 106 genes expressed during the cell cycle of Saccharomyces cerevisiae were used and genes were partitioned into five distinct clusters of sizes 33, 32, 21, 16, and 4. After removing the last observed time point, the agreements of signals (upregulated or downregulated) considering the predicted expression level were 72.7, 81.3, 76.2, 68.8, and 50.0%, respectively, for each cluster. The percentage of credibility intervals that contained the true values of gene expression for a future time was ~90%. The methodology performed well, providing a valid forecast of gene expression values by fitting an autoregressive panel data model. This approach is easily implemented with other time-series models and when Poisson and negative binomial probability distributions are assumed for the gene expression data.

Previsão Bayesiana de valores genéticos de touros por meio do modelo auto-regressivo para dados em painel / Bayesian forecasting of sires breeding values using autoregressive panel data model

Inferência Bayesiana do modelo auto-regressivo foi aplicado para dados em painel a dados reais de DEPïs de touros da raça Nelore publicadas entre 2000 e 2005. Na análise foram consideradas a função de verossimilhança exata e a obtenção de distribuições preditivas de dados futuros. Verificou-se ser recomendável o agrupamento dos animais em grupos homogêneos de acordo com a acurácia. Constatou-se também, que em média, a eficiência de previsão dos valores de DEPïs para um ano futuro é próxima de 80 por cento.

A Bayesian inference of autoregressive panel data model was applied to real data of Nelore sires Expected Progenie Difference (EPD) during a five-year period (2000-2005). The exact likelihood function and predictive distributions of future observations were considered. The results indicated the importance of sires grouping in homogeneous groups according to accuracy and showed forecast efficiency for EPD values in a future year around 80 percent.

Using a video conference to teach clinical clerks in a one-week cardiothoracic clerkship.

BACKGROUND: Students report that their operating room experience during specialty clerkships has been less than satisfactory. To deal with this and other problems in a 1-week cardiothoracic clerkship, a video conference system was introduced. METHODS: Three teaching strategies were used: a seminar dealing with the disease process and a description of the operative procedure; bedside pre-operative assessment of the patient, with a tutor; and a live video conference of the operation. The tutor observed the live video presentation with the students, initiating interaction with the operating surgeon and facilitating questions and discussion. Video quality was maintained by one camera connected to the headlight of the surgeon and another placed above the operative field. RESULTS: Both students and staff expressed a high degree of satisfaction in debriefing sessions and on a standard faculty evaluation form. CONCLUSIONS: This innovation in surgery specialty teaching contributes to the acquisition of educational objectives in the operating room and in a cardiothoracic clerkship.

Oral disease burden in patients undergoing prosthetic heart valve implantation.

BACKGROUND: Valvular heart disease predisposing to endocarditis and requiring prosthetic valve implantation is common among the elderly. Spontaneous bacteremias associated with acute or chronic oral/odontogenic infections may represent a far greater cumulative risk for the development of endocarditis than do occasional health care procedures administered in a professional setting. METHODS: To determine the oral disease burden in patients undergoing mechanical or bioprosthetic heart valve implantation, we performed a comprehensive clinical and radiographic regional examination on 156 consecutive patients, with emphasis on identifying acute and chronic oral/odontogenic infections and conditions. RESULTS: The mean number of remaining teeth in the cohort was 19.32; of these, 1.07 were carious, involving a mean number of 2.51 tooth surfaces. In addition, 15.38% of the patients had evidence of acute or chronic periapical abscesses, and 43.6% of the patients had moderate to advanced periodontitis. CONCLUSIONS: In view of the substantial morbidity and mortality associated with prosthetic valve endocarditis and based upon the high incidence of dental disease identified in patients undergoing valvular operations, routine preoperative dental assessment should be deemed a "medical necessity" by third-party payors. Appropriate therapeutic intervention should be initiated whenever possible before valve implantation.

Latex hypersensitivity: its prevalence among dental professionals.

Reports of hypersensitivity to latex are growing among oral health care workers, who have a high degree of exposure to latex products. The authors undertook a study to determine the prevalence of latex hypersensitivity among oral health care workers in a hospital dental practice. Among the 34 people who participated in the study, 12 percent had positive results in a skin prick test for latex. This suggests that the true prevalence rate of immediate hypersensitivity to latex in this group of oral health care workers is similar to that in other health care workers who use latex gloves frequently.

Effects of magnesium on myocardial function after coronary artery bypass grafting.

The effects of perioperative administration of magnesium sulfate on myocardial function was studied in patients with unstable angina (grade IV) undergoing coronary artery bypass grafting. Myocardial protection consisted of antegrade and retrograde continuous warm blood cardioplegia. Patients were randomly divided into two groups. Group A (50 patients) received intravenous magnesium sulfate (16 mmol) continuously from the time of anesthetic induction to aortic cross-clamping and a second dose (32 mmol) starting after the release of aortic cross-clamp until 24 hours later. Group B (48 patients) did not receive magnesium sulfate and served as control. Left ventricular stroke work index increased in group A from 34 +/- 3 g.m/m2 before operation to 42 +/- 3 g.m/m2, 45 +/- 2 g.m/m2, and 47 +/- 2 g.m/m2, 1, 6, and 12 hours after operation, respectively (p < 0.05 versus preoperative), and in group B from 33 +/- 3 g.m/m2 before operation to 38 +/- 3 g.m/m2, 40 +/- 2 g.m/m2, and 41 +/- 2 g.m/m2, 1, 6, and 12 hours after operation, respectively (p < 0.05). Left ventricular stroke work index was higher in group A 6 (p = 0.06), 12, and 24 hours (p < 0.05) after operation compared with group B. The incidence of ventricular arrhythmias requiring treatment was significantly higher (p < 0.05) in group B: 14 patients versus 1 patient in group A. Postoperative hypertension was more frequent in group B: 16 patients versus 2 patients in group A (p < 0.05). These results indicate that perioperative administration of magnesium sulfate may contribute to better myocardial recovery and fewer ventricular tachyarrhythmias after operation.

Frequency and significance of complete atrioventricular block after coronary artery bypass grafting.

Three hundred forty-eight consecutive patients were evaluated during 1985 and 1986 for the development of complete atrioventricular (AV) block after coronary artery bypass grafting. Cold (4 degrees) asanguineous potassium cardioplegia with temperature monitoring was used uniformly. AV block developed in 56 instances (16%). In 32 patients (group 1) the block was transient (less than 6 hours) and in 24 it was persistent (group 2). Left main coronary artery stenosis in conjunction with total obstruction of a dominant right coronary artery occurred more commonly in patients manifesting AV block (18 of 56, 32%) than in those without it (35 of 292, 12%) (p less than 0.05). Complete occlusion of a dominant right coronary artery was observed with equal frequency in patients with and without AV block. The presence of an ungraftable right coronary artery, however, was significantly more frequent in the AV block group: 16 of 37 (47%) vs 6 of 194 (3%) (p less than 0.01). Endarterectomy of the right coronary artery was performed in 8 of 24 patients (33%) with persistent AV block versus none in the patients with transient AV block (n = 32) or normal sinus rhythm postoperatively (n = 292) (p less than 0.0001). Persistent AV block (greater than 6 hours) was associated with myocardial infarction in 6 patients (25%) (p less than 0.05) and with low cardiac output in 18 patients (75%) (p less than 0.0001). In conclusion, AV block after myocardial revascularization was frequently associated with the presence of multivessel coronary disease and an ungraftable dominant right coronary artery. Persistent (greater than 6 hours) AV block was correlated with both perioperative myocardial infarction and low cardiac output.

Surgical treatment of post-infarction ventricular septal defect without concomitant myocardial revascularization.

Twenty one patients suffering from rupture of the ventricular septum (RVS) following acute myocardial infarction were operated upon between 1982-1985. Eighteen patients were operated upon urgently within 9.3 +/- 2.1 hours following diagnosis of RVS. In all, RVS occurred during the first infarction. None had concomitant myocardial revascularization. There were twelve operative survivors for an operative mortality of 42.5%. Two patients died 6 and 9 months postoperatively. All survivors are in functional class I, during a follow-up period of 14 to 56 months. The need for urgent repair of RVS is stressed and the value of concomitant coronary artery bypass is discussed.

Delayed respiratory depression following fentanyl anesthesia for cardiac surgery.

High-dose fentanyl anesthesia is widely used in cardiac surgery. Its immediate side-effects are well known. However, its late adverse effect manifested by extreme truncal rigidity, decreased chest wall compliance, hypoventilation, respiratory acidosis and hemodynamic instability is not sufficiently appreciated. Of 380 patients who underwent aortocoronary artery bypass under high-dose (100 micrograms/kg) fentanyl anesthesia, 29 (7.6%) developed the sudden onset of extreme thoracic and abdominal rigidity, leading to respiratory depression 2 to 6 h postoperative, after an apparently normal recovery from the anesthesia. In 15 patients, a high plasma level of fentanyl (5.2 to 7.8 ng/ml) correlated with the clinical events. Administration of naloxone or a muscle relaxant rapidly reversed this late complication of fentanyl, thought to be due to re-entry of fentanyl into plasma from deposits in adipose tissue, muscle and the GI tract, leading to a secondary peak in plasma fentanyl. It is more likely to be encountered when hypothermia, rewarming, and acidosis occur in the postoperative period. Awareness of this life-threatening complication is critical in patients undergoing surgery with fentanyl anesthesia.

The significance of bundle branch block in the immediate postoperative electrocardiograms of patients undergoing coronary artery bypass.

Three hundred sixteen consecutive patients undergoing coronary artery bypass were studied for postoperative electrocardiographic conduction disturbances. Fifty-five of these 316 patients had postoperative bundle branch block (Group 1). This group had a higher incidence of left main coronary stenosis, together with previous inferior myocardial infarction, than patients without postoperative conduction disturbances (Group 2). Perioperative myocardial infarction, low cardiac output, and death were significantly more common in Group 1 than in Group 2: 7.3% versus 1.9% for perioperative myocardial infarction, 16.4% versus 2.7% for low cardiac output, and 5.5% versus 0.8% for death. Analysis of the type of conduction disturbances indicates that the presence of a new complete left bundle branch block postoperatively in a patient undergoing coronary artery bypass is a sign of intraoperative myocardial damage. This damage is potentially lethal, especially in a patient with left main coronary stenosis and previous inferior myocardial infarction.

Successful repair of concomitant tear of the interventricular septum and right ventricular free wall after acute myocardial infarction.

Early repair of acute rupture of the ventricular septum after myocardial infarction is now the procedure of choice accepted by most centers. Rupture of the right ventricular free wall is rare and usually is accompanied by tamponade. The finding of coincidental right ventricular free wall rupture and acute ventricular septal defect following myocardial infarction and their successful repair are discussed in the following report.

Rupture of splenic abscess through the diaphragm.

Splenic abscess is an uncommon disease that has a high mortality rate if not treated surgically. With the aid of new diagnostic tools, such as ultrasonography, scanning and computerized axial tomography, it is possible to diagnose the entity antemortem. Even though it often has a nontypical clinical course, it may overlap other systemic diseases. We describe an unusual case of splenic abscess with rare complications, the operation and the outcome.