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A C Borges

Publications and source records attributed to A C Borges.

At least 19 recordsLinked to original sources
PubMed2006

Temporal and spatial dynamics of blocking and ripening effects on bacterial transport through a porous system: a possible explanation for CFT deviation.

The studies on transport of particles across porous systems are based on the Colloid Filtration Theory (CFT). According to CFT, the collision efficiency is constant along the system length [J.N. Ryan, M. Elimelech, Colloids Surf. A: Physicochem. Eng. Aspects 107 (1996) 1-56]. Decreasing values of collision efficiency have been reported, a phenomenon that has been interpreted as a deviation from the CFT [X. Li, T.D. Scheibe, W.P. Johnson, Environ. Sci. Technol. 38 (2004) 5616-5625; N. Tufenkji, J.A. Redman, M. Elimelech, Environ. Sci. Technol. 37 (2003) 616-623; N. Tufenkji, M. Elimelech, Langmuir 20 (2004) 10818-10828; N. Tufenkji, M. Elimelech, Langmuir 21 (2005) 841-852]. This paper presents data on transport of Bacillus megaterium spores through quartz sand columns. The occurrence of consecutive phases of increase and decrease of the values of C/C(0), the effluent spore concentration expressed as a fraction of the influent spore concentration, is reported. These patterns of change in C/C(0) were interpreted as the result of the concomitant occurrence of blocking and ripening, the prevalence of these phenomena in different moments of the experiment, and the spatial distribution of the prevalence of blocking and ripening effects along the porous system. It is argued that this spatial distribution in the predominance of blocking and ripening, what leads to the intensification of ripening at the entrance of the porous system, might be a possible explanation for the reported deviation from the CFT for experimental conditions where ripening and blocking take place.

Bacillus megaterium↗
PubMed2006

[Echocardiographic evaluation to select patients for cardiac resynchronization therapy].

Wide QRS complex and asynchronous myocardial contraction in heart failure are associated with poor prognosis. Resynchronization can be achieved by biventricular pacing (BVP), which leads to hemodynamic and clinical improvement and reverse remodeling, and may improve survival. However, there is a substantial subset of patients with wide QRS complexes in the electrocardiogram who does not improve despite BVP, and there are findings which suggest that resynchronization therapy may be also beneficial for heart failure patients with normal QRS duration. QRS width predicts the benefit of BVP only with limitation and only correlates weakly with echocardiographically determined myocardial asynchrony. Determination of asynchrony by tissue Doppler echocardiography seems to be the best predictor for improvement after BVP, although no consensus on the optimal method to assess asynchrony has yet been achieved. To date, most studies evaluating tissue Doppler echo in BVP were performed retrospectively and only one prospective study with patient selection for BVP according to echocardiography and electrocardiography criteria of asynchrony has been published. These new echocardiographic tools will help to prospectively select patients for BVP, help to guide implantation and to optimize device programming.

Arrhythmias, Cardiac↗
PubMed2005

[Adenocarcinoma-associated nonbacterial thrombotic endocarditis as the cause of recurrent strokes].

We describe a 60-year-old female patient without vascular risk factors diagnosed with cardioembolic ischemic stroke due to an atrial septal aneurysm with a right-to-left shunt. However, further investigation after recurrent strokes revealed a nonbacterial thrombotic endocarditis (NBTE) caused by a metastatic adenocarcinoma. The presented case illustrates the difficulties in establishing the diagnosis of NBTE premortally and points out the importance of repeated echocardiographic evaluations of cardiac valves and serological examination of tumor markers in patients with recurrent strokes of unknown origin.

Adenocarcinoma↗
PubMed2005

[Left atrial myxoma: second recurrence 20 years after the first operation].

We report about a 52-year old woman, who underwent a resection of a left atrial myxoma 20 years ago. Twelve years later she suffered from exertional dyspnea. Echocardiography revealed a recurrent myxoma. This was resected. Eight years later the woman suffered from disturbances of heart rhythm and from angina pectoris. The coronary arteries were normal, but a recurrent left atrial myxoma was found and operated. We conclude a long-term follow-up is inevitable in patients after the resection of a myxoma.

Adult↗
PubMed2004

Echocardiographic AV-interval optimization in patients with reduced left ventricular function.

BACKGROUND: Ritter's method is a tool used to optimize AV delay in DDD pacemaker patients with normal left ventricular function only. The goal of our study was to evaluate Ritter's method in AV delay-interval optimization in patients with reduced left ventricular function. METHODS: Patients with implanted DDD pacemakers and AVB III degrees were assigned to one of two groups according to ejection fraction (EF): Group 1 (EF > 35%) and Group 2 (EF < 35%). AV delay optimization was performed by means of radionuclide ventriculography (RNV) and application of Ritter's method. RESULTS: For each of the patients examined, we succeeded in defining an optimal AV interval by means of both RNV and Ritter's method. The optimal AV delay determined by RNV correlated well with the delay found by Ritter's method, especially among those patients with reduced EF. The intra-class correlation coefficient was 0.8965 in Group 1 and 0.9228 in Group 2. The optimal AV interval in Group 1 was 190 +/- 28.5 ms, and 180 +/- 35 ms in Group 2. CONCLUSION: Ritter's method is also effective for optimization of AV intervals among patients with reduced left ventricular function (EF < 35%). The results obtained by RNV correlate well with those from Ritter's method. Individual programming of the AV interval is fundamentally essential in all cases.

Aged↗
PubMed2004

[Neurological complications of infective endocarditis].

Infective endocarditis involves the brain in 20-40% of cases. The neurologic syndrome often is the presenting feature. The most frequent neurologic complication is cerebral ischemia. In these patients and those with intracranial hemorrhage, a heart murmur as well as systemic signs of inflammation point to endocarditis. The encephalopathy in endocarditis is mostly due to cerebral infarction. In bacterial meningitis and brain abscess an uncommon isolate arouses suspicion. The most important therapy is antibiotic treatment. Valve replacement improves outcome; in the acute phase of endocarditis, however, it is only necessary in a third of the patients. Neurologic complications interfere with the timing of the valve replacement. If it is urgently required, its risk is reasonable within 3 days after cerebral ischemia; if possible 2-4 weeks should be waited. Cases of successful valve replacement within 4 weeks after intracranial hemorrhage have been reported, but it is recommended to postpone it for 4-6 weeks. There are no data available for the other neurologic complications. Even today patients with endocarditis challenge the diagnostic and therapeutic capacity of various disciplines.

Brain Diseases↗
PubMed2004

Multislice CT coronary angiography: evaluation of an automatic vessel detection tool.

PURPOSE: To investigate the potential of a new detection tool for multislice CT (MSCT) coronary angiography with automatic display of curved multiplanar reformations and orthogonal cross-sections. MATERIALS AND METHODS: Thirty-five patients were consecutively enrolled in a prospective intention-to-diagnose study and examined using a MSCT scanner with 16 x 0.5 mm detector collimation and 400 ms gantry rotation time (Aquilion, Toshiba). A multisegment algorithm using up to four segments was applied for ECG-gated reconstruction. Automatic and manual detection of coronary arteries was conducted using the coronary artery CT protocol of a workstation (Vitrea 2, Version 3.3, Vital Images) to detect significant stenoses (> or = 50 %) in all segments of > or = 1.5 mm in diameter. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of conventional coronary angiography. RESULTS: The overall sensitivity, specificity, nondiagnostic rate, and accuracy of the automatic and manual approach were 90 vs. 94 %, 89 vs. 84 %, 6 vs. 6 %, and 89 vs. 88 %, respectively (p = n. s.). The vessel length detected with the automatic and manual approach were highly correlated for the left main/left anterior descending (143 +/- 30 vs. 146 +/- 24 mm, r = 0.923, p < 0.001), left circumflex (94 +/- 35 vs. 93 +/- 33 mm, r = 0.945, p < 0.001), and right coronary artery (145 +/- 36 vs. 144 +/- 37 mm, r = 0.925, p < 0.001). The time required to create reformations along the coronary arteries was significantly shorter with the automatic tool compared to the manual approach (203 +/- 77 vs. 391 +/- 104 sec, p < 0.005). In 90 % of the coronary branches automatic detection required less time than the manual approach. CONCLUSION: Automatic coronary vessel detection is feasible and reduces the time required to create reformations by a factor of approximately two without deteriorating the diagnostic accuracy.

Aged↗
PubMed2004

[Evaluation of regional wall motion abnormalities of the heart--comparison with doppler tissue echocardiography, MR-tagging and levocardiography].

PURPOSE: To compare the visual analysis of magnetic resonance imaging (MRI) with the tagging technique and Doppler tissue echocardiography with invasive ventriculography in detecting and quantifying regional left ventricular wall motion abnormalities. MATERIALS AND METHODS: Sixteen patients with coronary artery disease and a history of prior myocardial infarction underwent invasive ventriculography, Doppler tissue echocardiography and MR-tagging within one week. Regional wall motion abnormalities (WMA) were detected in all patients. WMA were graded as normal = 1; hypokinetic = 2; akinetic = 3; or dyskinetic = 4. For agreement between MRI, echocardiography, and ventriculography the kappa coefficient (kappa) according to Cohen was calculated. RESULTS: The kappa coefficient (kappa) was 0.962 for agreement between MRI and echocardiography and 0.602 for agreement between MRI and ventriculography as well as between echocardiography and ventriculography. CONCLUSION: Reliable analysis of regional left ventricular wall motion abnormalities is feasible using visual analysis of MR-tagging. MRI and Doppler tissue echocardiography detect more WMA than invasive ventriculography and grade them as more severe.

Aged↗
PubMed2004

Stirred anaerobic sequencing batch reactor containing immobilized biomass: a behavior study when submitted to different fill times.

The effect of the filling stage on the behavior of a mechanically stirred anaerobic sequencing batch reactor containing biomass immobilized on 1 cm polyurethane foam cubes was investigated. The reactor was made of acrylic with a capacity of 6.3 L, treating per cycle 2.5 L synthetic low-strength wastewater with a concentration of 500 mgCOD/L, at 30+/-1 degrees C. Eight-hour cycles (tC) and agitation of 500 rpm were utilized. At the beginning of each cycle 60% of the wastewater volume was treated, sufficient to completely cover the bed. The remaining volume was added at different fill times (tF) of 10, 120, 240, 260 and 480 min. The results obtained showed that ratios of tF/tC < or = 0.5 enabled organic matter removal higher than 75% and 70% for filtered and non-filtered samples, respectively. Ratios of tF/tC > 0.5, despite operation stability, resulted in loss of efficiency and formation of viscous material, similar to extra-cellular polymeric substances.

Bacteria, Anaerobic↗
PubMed2003

[Left ventricular pseudoaneurysm after mitral valve replacement].

We report about a woman with a rare complication after mitral valve replacement 24 years ago. The patient had a massive hemorrhage some hours after operation. We performed invasive diagnostics because of an increasing pressure gradient across the prosthesis and revealed a left ventricular pseudoaneurysm. Before the planned reoperation the patient died suddenly. As the cause of death, we assumed a rupture of the pseudoaneurysm.

Adult↗
PubMed2001

Endotracheal balloon dilatation and stent implantation in benign stenoses.

BACKGROUND: Tracheal reconstruction is the treatment of choice in nontumorous tracheal stenoses, but recurrences and concomitant medical conditions limit this approach. We investigated the outcome after balloon dilatation and silicone stent implantation. METHODS: Forty-two patients with inoperable tracheal stenoses underwent balloon dilatation and afterward silicone stent implantation. Patients were divided into two groups, in group A 24 patients received tracheal stents as a temporary treatment. In group B, definitive stenting was done in 18 patients with severe concomitant medical conditions that did not allow for stent removal. RESULTS: Immediate results were satisfactory in all patients. In group A, stents could be removed in 12 patients after a mean interval of 20 months. Restenting was not required during the following 18.9 months. Twelve patients are still waiting for stent removal after a mean follow-up of 20 months. In group B, mean follow-up is now 48.4 months. Complications included retained secretions, dislocation, and granuloma formation. CONCLUSIONS: Stenting after balloon dilatation is safe and effective in benign tracheal stenoses. After temporary use, stents can be removed when local and general conditions permit. In all other patients, stenting proved beneficial for 5 years as more definitive treatment.

Adult↗
PubMed2001

Right atrial thrombus treated successfully with abciximab and heparin.

We report here a case of right atrial thrombus diagnosed by echocardiography in a 25-year-old female patient with Hodgkin's disease receiving chemotherapy and heparin. After 24 hours therapy with the glycoprotein IIb/IIIa receptor antagonist (abciximab) with concomitant heparin the complete dissolution of the thrombus could be demonstrated by transesophageal echocardiography. To our knowledge this case represents the first use of abciximab in right atrial thrombosis.

Abciximab↗
PubMed2001

Characterization of pectin lyase produced by an endophytic strain isolated from coffee cherries.

AIMS: The effect of endophytic bacterial activity on the quality of coffee beverage was studied. METHODS AND RESULTS: A survey of the micro-organisms in coffee cherries was performed before harvesting, and their growth on the main nutrients available in coffee cherries was determined in vitro. CONCLUSION: Many endophytic bacteria were isolated from surface-sterilized coffee cherries. One of the pectinolytic strains was physiologically and phenotypically characterized, and was tentatively identified by partial 16S rDNA sequencing as Paenibacillus amylolyticus. This endophytic strain produced an extracellular pectinase with maximal activity at 40 degrees C and pH 7.9, and was thermostable up to 45 degrees C. EDTA and metal ions had little effect on pectin lyase activity. Km and Vmax values were 4.6 mg ml(-1) and 94.0 10(-8) mol min(-1) ml(-1), respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Pectin lyases have been found in fungi but rarely in bacteria, and this isolate is a promising tool for regulation studies of these enzymes.

Bacillaceae↗
PubMed2001

The prognostic value of myocardial viability recognized by low dose dipyridamole echocardiography in patients with chronic ischaemic left ventricular dysfunction.

AIMS: The aim of this study was to assess the prognostic value of myocardial viability recognized as a contractile response to vasodilator stimulation in patients with left ventricular dysfunction in a large scale, prospective, multicentre, observational study. METHODS AND RESULTS: Three hundred and seven patients (mean age 60 +/- 10 years) with angiographically proven coronary artery disease, previous (>3 months) myocardial infarction and severe left ventricular dysfunction (ejection fraction <35%; mean ejection fraction: 28 +/- 7%) were enrolled in the study. Each patient underwent low dose dipyridamole echo (0.28 mg x kg(-1) in 4 min). Myocardial viability was identified as an improvement of >0.20 in the wall motion score index. By selection, all patients were followed up for a median of 36 months. One-hundred and twenty-four were revascularized either by coronary artery bypass grafting (n=83) or coronary angioplasty (n=41). The only end-point analysed was cardiac death. In the revascularized group, cardiac death occurred in one of the 41 patients with and in 16 of the 83 patients without a viable myocardium (2.4% vs 19.3%, P<0.01). Outcome, as estimated by Kaplan-Meier survival, was better for patients with, compared to patients without, a viable myocardium, who underwent coronary revascularization (97.6 vs 77.4%, P=0.01). Using a Cox proportional hazards model, the presence of myocardial viability was shown to exert a protective effect on survival (chi-square 4.6, hazard ratio 0.1, 95% CI 0.01-0.8, P<0.03). The survival rate in medically treated patients was lower than in revascularized patients irrespective of the presence of a viable myocardium (79.7% vs 86.2, P=ns). CONCLUSION: In severe left ventricular ischaemic dysfunction, myocardial viability, as assessed by low dose dipyridamole echo, is associated with improved survival in revascularized patients.

Aged↗
PubMed2001

[Left ventricular reduction surgery: pre- and postoperative evaluation by cine MRI].

AIM: To evaluate the role of cine magnetic resonance imaging (MRI) in the preoperative assessment and postoperative follow-up of patients undergoing left ventricular (LV) reduction surgery. PATIENTS AND METHODS: 6 patients with cardiomegaly were examined on a 1.5 T MR imager before and after LV reduction surgery. The heart was imaged along the short and long axes using a breath-hold ECG-triggered cine gradient-echo sequence for assessing ventricular and valvular morphology and function and performing volumetry (end-diastolic and end-systolic volumes, ejection fraction). RESULTS: Postoperatively, the mean ejection fraction increased from 21.7% to 33.4% and the end-diastolic and end-systolic left ventricular volumes decreased in all patients (304.0 and 252.5 ml before to 205.0 and 141.9 ml after surgery). Mean myocardial mass decreased slightly from 283.8 g to 242.7 g. Differences were significant for all parameters (p < 0.05). MRI allowed for the reliable assessment of post-operative valve morphology and yielded additional findings such as the presence of mitral valve insufficiency or ventricular thrombus. CONCLUSIONS: Cine MRI provides relevant information prior to left ventricular reduction surgery and reliably depicts functional and morphological changes in the early post-operative follow-up.

Aged↗