Scatter Search and Path Relinking

Scatter search (SS) and path relinking (PR) are evolutionary methods that have been successfully applied to a wide range of hard optimization problems. The fundamental concepts and principles of the methods were first proposed in the 1970s and 1980s, and were based on formulations, dating back to the 1960s, for combining decision rules and problem constraints. The methods use strategies for search diversification and intensification that have proved effective in a variety of optimization problems and that have sometimes been embedded in other evolutionary methods to yield improved performance. This paper examines the scatter search and path relinking methodologies from both conceptual and practical points of view, and identifies certain connections between their strategies and those adopted more recently by particle swarm optimization. The authors describe key elements of the SS & PR approaches and apply them to a hard combinatorial optimization problem: the minimum linear arrangement problem, which has been used in applications of structural engineering, VLSI and software testing.

Mitral valve repair for ischemic mitral regurgitation using the Carpentier-McCarthy-Adams IMR ETlogix® ring: medium-term echocardiographic findings

The aims of this study were to review the principles underlying use of the Carpentier-McCarthy-Adams IMR ETlogix® asymmetric annuloplasty ring for the treatment of chronic ischemic mitral regurgitation and to report medium-term clinical outcomes observed at our center. The in-hospital mortality rate was 2.8%. Echocardiography at hospital discharge confirmed the absence of mitral regurgitation in 88.8% of patients. Patients underwent clinical and echocardiographic follow-up (median duration, 23 months; range, 12-44 months). Late follow-up echocardiography demonstrated the recurrence of moderate mitral regurgitation in 5.7% of patients and of moderate-to-severe mitral regurgitation in 2.9%. The rate of survival free from recurrence of ≥grade-2 mitral regurgitation was 95.2% at 15 months and 88.9% at 25 months. Mitral valve repair using the asymmetric Carpentier-McCarthy-Adams IMR ETlogix® ring in patients with chronic ischemic mitral regurgitation enabled regurgitation to be effectively corrected by producing asymmetric changes in the morphology of the mitral ring. Medium-term outcomes, with regard to the degree of mitral valve competence, were excellent.

[Neuroprotection in Parkinson's disease: analysis though group of experts' methodology]

INTRODUCTION

Currently used antiparkinsonian drugs neither stop nor slow-down the progressive nature of the disease. The final phase of PD is characterized by the presence of symptoms and signs resistant to dopaminergic agents, such as depression, dementia, freezing and falls. Therefore, it is urgent to develop therapies able to positively modify this outcome. Despite neuroprotection is a research priority in PD, no effective strategies have been found so far.

METHOD

A key informants study was conducted. A group of experts in PD fulfilled a questionnaire of 10 questions to explore the most important topics related to neuroprotection. Afterwards a consensus about the current situation of neuroprotection in PD was established and future directions of development were suggested.

RESULTS

Most of the answers emphasized the need of new concepts, the limitations of animal models and the difficulties in the difficulties in demonstrating a neuroprotective effects in humans owing to a lack of biomarkers. Some of the experts believe that we are already exerting a disease modifying effect.

CONCLUSIONS

The concept of neuroprotection should be widened. Animal models should be improved. A reliable biomarker to start neuroprotective therapies long before the appearance of motor symptoms and to evaluate the neuroprotective effect of any therapy should be urgently developed.

A case of lipoatrophy with insulin detemir

Lipoatrophy is a rare cutaneous side-effect that can develop at the site of insulin injection. Since the introduction of human recombinant insulin the number of cases has decreased although cases have been reported in association with the use of rapid acting insulin analogues and continuous subcutaneous insulin infusion (CSII), recently one case has been reported with the use of insulin glargine. Insulin-induced lipoatrophy is a subcutaneous fat atrophy at the sites of injection which is relevant not only because of the cosmetic problem, but also because of the variability of absorption it causes in the site of injection. This report describes a patient with a type 1 diabetes mellitus who develops a lipoatrophy induced by insulin detemir. To our understanding this is one of the first reported cases of lipoatrophy induced by insulin detemir.

Trace elements removal from water using modified activated carbon

This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion-sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $23 and compatibility with the traditional household filtration system.

[Aortic valve replacement with a Cryolife O'Brien stentless bioprosthesis]

INTRODUCTION AND OBJECTIVES

The Cryolife O'Brien xenograft is a stentless bioprosthesis constructed from noncoronary leaflets from three porcine aortic valves. The aim of this study was to investigate short-term results after aortic valve replacement with this composite xenograft.

METHODS

Since October 1993, Cryolife O'Brien bioprostheses have been implanted in 210 patients. The patients' mean age was 70.9 (7.5) years (range 23-83 years). The indication was aortic stenosis in 132 cases, aortic insufficiency in 25 cases, and both lesions in 53 cases. Valve function was studied by echocardiography preoperatively, at discharge, and 6 and 12 months postoperatively.

RESULTS

The 30-day mortality rate was 5.2% (11/210). Over time, the mean gradients decreased and the effective area index increased. In addition, the left ventricular mass index, wall thickness, and septum thickness also decreased shortly after surgery.

CONCLUSIONS

Use of the Cryolife O'Brien stentless bioprosthesis demonstrated satisfactory results at 1-year follow-up. Additional follow-up is required to assess the performance of this bioprosthesis over the long term.

[Preoperative risk evaluation in beating-heart coronary artery bypass surgery]

INTRODUCTION AND OBJECTIVES

Operative risk stratification scales for use in cardiac surgery have been developed for patients who undergo procedures using extracorporeal circulation. The aims of the present study were to investigate the use of six preoperative risk stratification scales in patients undergoing beating-heart surgery and to identify risk factors for major complications and mortality in our group of patients who underwent revascularization using this approach.

PATIENTS AND METHOD

Between January 1997 and December 2002, we performed 762 coronary artery bypass operations on the beating heart; 61 patients suffered major complications (8%) and 25 died (3.3%). Risk factors for major complications and death were identified using logistic regression analysis of prospectively collected data. The following risk scores were calculated for each patient: Parsonnet 95, Parsonnet 97, Euroscore, Cleveland, Ontario, and French. Receiver operating characteristic curves were used to compare the ability of each scale to predict mortality and major complications.

RESULTS

In our patient group, the preoperative variables associated with increased risk were: need for cardiopulmonary resuscitation, renal dysfunction, peripheral vasculopathy, and the presence of severe left main coronary artery disease, three-vessel disease, or an impaired ejection fraction.

CONCLUSIONS

Mortality and major complications were best predicted by the Parsonnet 95 and Euroscore scales.

Off-pump total arterial revascularization: our experience

BACKGROUND AND AIM

Off-pump coronary artery bypass grafting with both the internal thoracic arteries, such as the Tector technique, can reduce the morbidity associated with extracorporeal circulation and aortic cross-clamp. The aim of the present study is to describe our experience and the results obtained.

METHODS

From April 1998 to December 2003, the off-pump Tector technique was performed on 743 patients, of whom 621 were male (83.5%), with a mean age of 65.3 +/- 9.5 years (23-90). Preoperative risk factors were diabetes mellitus in 29.5% and peripheral vasculopathy in 14.7% of the patients. Angiography showed left main disease in 25.6% and triple-vessel disease in 50.3% of the patients, with a mean ejection fraction of 60%+/- 13% (23-88). Both the internal thoracic arteries were harvested using the skeletonization technique and were anastomosed as "Y" or "T" grafts. Intraoperative graft patency was checked using a Doppler flowmeter.

RESULTS

A total of 2028 distal anastomoses were performed, the average being 2.7 (1 to 5) per patient. At least three distal anastomoses were undertaken in 62% of the patients. Postoperative complications included atrial fibrillation in 40 patients (5.4%), myocardial infarction in 24 (3.2%), mediastinitis and reoperation for bleeding in 7 (0.9%) and stroke in 3 (0.4%). Twenty-four patients (3.2%) died in the first month postoperatively.

CONCLUSIONS

The off-pump Tector technique appears to be safe, showing a low surgical morbidity.

[Early alterations of adrenergic cardiac function in Parkinson's disease]

INTRODUCTION

Myocardial sympathetic (adrenergic) function is significantly affected in patients with idiopathic Parkinson's disease (PD) as is deduced from the cardiac scintigraphy evaluation with 123I-metaiodobenzylguanidine (123I-MIBG).

PATIENTS AND METHODS

In the present study, 60 patients with PD were studied compared to 17 normal subject without neurological disease. The clinical parameters evaluated were severity of the condition (measured by Hoehn and Yahr Scale), vegetative manifestations, development time and use and type of medication taken. Myocardial adrenergic function was analyzed by imaging with 123I-MIBG. Early (15 min) and delayed (4 h) images of the anterior view were obtained after injection of 123I-MIBG. Qualitative and semiquantitative 123I-MIBG uptake was quantified by calculating a heart-to-mediastinum (H/M) ratio.

RESULTS

We found a significant decrease of H/M ratio in patients with PD as compared with controls (p < 0.01) independently of development time, severity of the condition, use of medication or vegetative manifestations.

CONCLUSIONS

There is an important noradrenergic alteration in PD, that can be detected from early stages and does not exist in other parkinsonisms caused by a different pathogenic mechanism.

[123 I-MIBG myocardial sympathetic innervation scintigraphy and Parkinson's disease. Preliminary results]

OBJECTIVES

Cardiac sympathetic function in patients with Parkinson's disease (PD) is significantly impaired. Cardiac scintigraphy with 123I-metaiodobenzylguanidine (123I-MIBG) is used to assess cardiac sympathetic function.

METHODS

A total of 29 consecutive patients with PD and 10 control subjects without neurological disease were studied. Myocardial imaging with 123I-MIBG was performed to evaluate cardiac sympathetic function. Early and delayed images of the anterior view were obtained at 15 min. and 4 h. after injection of 123I-MIBG, respectively. 123I-MIBG uptake was quantified qualitatively and semiquantitatively by calculating a heart-to-mediastinum (H/M) ratio.

RESULTS

The heart/mediastinum ratio was markedly reduced in patients with PD (I to IV on the Hoehn and Yahr scale) when compared to the control subjects (p < 0.05). This finding was independent of the length and severity of the disease or the pharmacological treatment of the patients. None of the control subjects showed decrease in myocardial 123I-MIBG uptake.

CONCLUSIONS

Our findings indicate that a decrease in myocardial accumulation of 123I-MIBG was observed in the early stages of PD. This suggests that the measurement of 123I-MIBG may help the early diagnosis of PD, and can be used to detect cardiac autonomic dysfunction, especially in patients without typical signs and symptoms.

Triflusal versus oral anticoagulation for primary prevention of thromboembolism after bioprosthetic valve replacement (TRAC): rationale and design for a prospective, randomized, co-operative trial

Antiplatelet agents are used for prevention of thromboembolism in surgical patients and in patients with chronic atrial fibrillation. However, up-to-date results of randomized studies comparing antiplatelet agents and oral anticoagulation have not been reported. The aim of this study is to compare the efficacy and safety profile of triflusal versus acenocoumarol for primary prevention of thromboembolism in the early postoperative period after implantation of a bioprosthesis. This is a prospective, multicentric, randomized, open, pilot trial in which four acute-care teaching hospitals participate. Patients will be randomly assigned to treatment with triflusal or acenocoumarol the day before valve replacement with a bioprosthesis. Primary outcome will be the combined endpoint of the rate of either thromboembolism or hemorrhage and valve-related mortality in each treatment group. Secondary outcomes will include the analysis of each of these rates separately together with permanent valve-related impairment according to the guidelines for reporting morbidity and mortality after cardiac valvular operations. A total of 200 patients will be recruited in a competitive manner (100 patients per arm) over an 18-month period. The study will be completed in 2 years. Treatment assigned will be open to investigators and patients because of the need of blood monitoring and dosage adjustment in oral anticoagulant therapy. In order to minimize the bias, randomization is centrally performed. The study medication will be given for 3 months being discontinued afterwards. Follow-up visits are scheduled at the time of patient's inclusion in the study and at 1, 3, and 6 months thereafter. Homogeneity of groups will be analyzed using the Student's t test, the Mann-Whitney U test, and the chi-square test, when appropriate. Rates of thromboembolism and hemorrhage will be calculated with the hazard function. In conclusion, antiplatelet treatment for patients undergoing valve replacement with a bioprosthesis is clinically relevant because of avoidance of inconveniences of oral anticoagulation (monthly blood testing, dosage adjustment) and decreased risk of bleeding. In case the results favor the use of antiplatelet drugs in these patients, this study will contribute to future development of strategies in the prevention of thromboembolism.

Chromate reduction in Serratia marcescens isolated from tannery effluent and potential application for bioremediation of chromate pollution

Pollution of aquatic systems by heavy metals has resulted in increasing environmental concern because they cannot be biodegraded. One metal that gives reason for concern due to its toxicity is chromium. Cr(VI) and Cr(III) are the principal forms of chromium found in natural waters. A chromate-resistant strain of the bacterium S. marcescens was isolated from tannery effluent. The strain was able to reduce Cr(VI) to Cr(III), and about 80% of chromate was removed from the medium. The reduction seems to occur on the cell surface. Transmission electron microscopic examination of cells revealed that particles were deposited on the outside of bacterial cells. A stable biofilm was formed in less than 10 h, reaching around 1010 cfu attached per milligram of activated carbon. These findings demonstrate that immobilized S. marcescens might be used in industrial waste treatment processes.

Taxonomic study of extreme halophilic archaea isolated from the "Salar de Atacama", Chile

A large number of halophilic bacteria were isolated in 1984-1992 from the Atacama Saltern (North of Chile). For this study 82 strains of extreme halophilic archaea were selected. The characterization was performed by using the phenotypic characters including morphological, physiological, biochemical, nutritional and antimicrobial susceptibility test. The results, together with those from reference strains, were subjected to numerical analysis, using the Simple Matching (S(SM)) coefficient and clustered by the unweighted pair group method of association (UPGMA). Fifteen phena were obtained at an 70% similarity level. The results obtained reveal a high diversity among the halophilic archaea isolated. Representative strains from the phena were chosen to determine their DNA base composition and the percentage of DNA-DNA similarity compared to reference strains. The 16S rRNA studies showed that some of these strains constitutes a new taxa of extreme halophilic archaea.

Compound odontoma--diagnosis and treatment: three case reports

Odontomas are the most common type of odontogenic tumors and generally they are asymptomatic. This paper describes three cases of compound odontomas diagnosed in children due to dislodgement or over-retention of primary anterior teeth and/or swelling of the cortical bone. In all cases, the surgical excision of the lesions was performed and, in one case, orthodontic treatment was adopted in order to move an impacted permanent tooth to its normal position. The results achieved indicate that the early diagnosis of odontomas allows the adoption of a less complex and expensive treatment and ensures better prognosis.