The effect of electron correlation on the conformational space of melatonin.

The pineal gland hormone melatonin regulates several physiological processes including circadian rhythm and also alleviates oxidative stress-induced degenerative diseases. In spite of its important biological roles, no high level ab initio conformational study has been conducted to reveal its structural features. In this work, the conformational flexibility of melatonin was investigated using correlated ab initio calculations. Conformers, obtained previously at the Hartree-Fock level (HF/6-31G*), were fully optimized using second order Møller-Plesset perturbation theory applying the frozen core approximation (MP2(FC)/6-31G*). Furthermore, single-point MP4(SDQ,FC)/6-31G*//MP2(FC)/6-31G* computations were performed to investigate the effect of higher order perturbation terms. The HF and MP2 conformational spaces are considerably different: the initial 128 structures converged into 102 different local minima as confirmed by frequency calculations; 28 new minima appeared and 26 previous HF local minima disappeared; no "all-trans" C3 side chain conformations are seen at the MP2(FC) level. The MP2 global minimum conformation is stabilized by an aromatic-side chain interaction.

Free-floating thrombus of the carotid artery: literature review and case reports.

BACKGROUND: Free-floating thrombus (FFT) of the carotid artery is an uncommon entity that usually presents as an acute emergency. Management is based on case reports and series because the natural history and optimal treatment are unknown. This study was conducted to systematically review the world literature in an attempt to better understand FFT, its presentation, distribution, management, and outcome. METHOD: A literature search in all languages was performed of the PubMed database (> or =1950s) and Medline database (1966-November 2004). All relevant articles were reviewed and their references analyzed in a similar manner for further literature. Cases from the authors' institutions were reviewed as well. All cases within the reports were individually assessed for inclusion or exclusion. Inclusion required that the FFT originate or anchor within the carotid artery (ie, excluding emboli, arch thrombi with extensions into the carotid artery), be partially occluding (ie, excluding occlusions, "string-sign," microscopic thrombus), and ideally have an elongated or protrusive morphology, circumferential flow around the distal portion, and cyclical motion with the cardiac cycles. RESULTS: There were 61 reports reviewed, of which 43 contained FFT cases. These reports had 342 cases (including the current series) that were reviewed, of which 145 met our inclusion criteria. A database was created for qualitative and quantitative assessment of all cases. When data were pooled, appropriate statistical analysis was performed. A limitation of the study is that FFT is under-reported and ill defined, which limited the analysis in quantity and quality. In addition, reporting is not uniform, and therefore, significant data were not always present. In attempting to define FFT and include or exclude cases, subjectivity is inherent. CONCLUSIONS: FFT is more frequently reported in men than women, with a ratio of nearly 2:1 (P < .0001), and at a younger age than in most patients with carotid disease (P < .0001 when compared with North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and Asymptomatic Carotid Surgery Trial). Symptoms are present in 92% of patients. There was a trend for patients with FFT to be hypercoagulable (47% of those serologically tested). The internal carotid artery was the most commonly affected (75%), with atherosclerosis being the most common associated pathology. Medical and surgical management have both been used, with neither clearly superior to the other. Medical management for stabilizing neurologic deficits has less risk and less benefit than surgical intervention.

Infrainguinal endovascular procedures should be reserved for patients who do not have good open surgical options.

This article is the result of a debate. The motion proposed was "Infrainguinal endovascular procedures should be reserved for patients who do not have good open surgical options.'' Arguments in favor of the motion were offered by Daniel J. Reddy of Henry Ford Hospital in Detroit, MI, and arguments against the motion were offered by Peter Kalman of Loyola University Medical Center in Maywood, IL.

Neovascularization in acute venous thrombosis.

OBJECTIVE: The aim of this study was to describe the phenomenon of arteriovenous fistula (AVF) formation in venous thrombus. METHODS: Patients referred to the vascular laboratory for evaluation for deep venous thrombosis were included. Duplex ultrasound scanning was used to detect flow within the thrombus. The flow patterns and the resistivity index were obtained in the veins above/proximal and below/distal to the thrombus, in the adjacent arteries, and within the perivenous vessels. Patients with trauma, hemodialysis access, endovenous ablation, known AVF, or inflammatory conditions were excluded. RESULTS: There were 22 patients with AVF flow in thrombosed veins. Deep veins were involved in 15 cases and superficial veins in the remainder. Perivenous vessels feeding the AVF in the thrombus could be clearly identified in 16 patients (19 vein segments). In 21 of 22 patients, multiple flow channels were present throughout the involved thrombosed vein segment. These flow channels were isolated to a single vein segment. They measured <4 cm in length in 19 cases and were more extensive in the remaining three. Reflux within the vein segment was identified in 13 cases. Local symptoms that could be attributed to the arterialization of thrombosed veins occurred in four cases, and none of the patients manifested systemic symptoms. The flow within the thrombus had high end-diastolic velocities with a mean resistivity index of 0.48 (SD, 0.08), which is typical of a fistula flow pattern. The flow in the main arteries was unaffected. CONCLUSION: Neovessels were found with AVF flow in thrombi of superficial and deep veins. They had variable length and multiple flow channels, with inflow from perivenous arteries. The flow in the adjacent main arteries was not affected, and no systemic symptoms were detected. The exact etiology and natural history of this phenomenon are not known, and its clinical significance is unclear.

The vascular surgeon's role in risk factor modification: results of a survey.

PURPOSE: Comprehensive care of vascular patients includes attention to atherosclerotic risk factor management. We surveyed members of the Midwestern Vascular Surgical Society (MVSS) with the following objectives: (1) to determine the usual practice pattern with respect to risk factor inquiry, screening, and intervention, (2) to determine which risk factors vascular surgeons believe are important for patients with peripheral arterial disease, and (3) to determine the vascular surgeon's confidence for management of each risk factor. METHODS: A survey was mailed to all MVSS members and two additional notifications were sent for initial nonresponders. Data regarding practice environment and local resources available to each surgeon were recorded. Questions were designed to determine the prevalence of risk factor inquiry and screening, grading of the importance of each risk factor, and the vascular surgeon's confidence in the management of each risk factor. RESULTS: The survey was completed by 219 (56%) of 391 of MVSS members. The average age of the responders was 53.1 +/- 9.3 years, and 94.1% were men. Seventy-four percent of the surgeons dedicate 90% to 100% of their time to vascular surgery, and 89% dedicate more than 50%. Seventy-seven percent of responders work in a private institution and 23% in a public hospital. The surgeon's practice had a full- or part-time affiliation with a medical school in 62% and was entirely community-based in 38%. A high proportion of surgeons inquire about each risk factor, but only a minority performs the actual screening of the risk factors, with the exception of hypertension. Diabetes mellitus and smoking were believed to be very important risk factors, hypertension and lipids of moderate importance, and exercise and activity, nutrition, and homocysteine level of low importance. The surgeons' confidence in risk factor management was low to moderate for most risk factors, but high for smoking and exercise. Despite these responses, only 10% of vascular surgeons thought that they should be primarily responsible for risk factor management. CONCLUSIONS: Vascular surgeons must provide a comprehensive approach to risk factor management for their patients. This can be conducted through the establishment of multidisciplinary risk factor programs or by the surgeon in certain cases when outside resources are not available. Risk factor management must be emphasized in vascular continuing medical education programs to enable surgeons to be confident with management.

Arteriovenous access: managing common problems.

The creation and maintenance of hemoaccess occupies a significant portion of most vascular and general surgery practices. In this article, the methods used to detect hemoaccess at risk for failure and the endovascular and surgical techniques used to prolong or restore their patency are reviewed. Also, the management of hemoaccess infection, aneurysmal degeneration, false aneurysm formation, and symptomatic arterial steal syndrome are described.

To what extent has endovascular aneurysm repair influenced abdominal aortic aneurysm management in the state of Illinois?

PURPOSE: This study was performed using population-based data to determine the changing trends in the techniques for abdominal aortic aneurysm (AAA) repair in the state of Illinois during the past 9 years and to examine the extent to which endovascular aneurysm repair (EVAR) has influenced overall AAA management. METHODS: All records of patients who underwent AAA repair (1995 to 2003 inclusive) were retrieved from the Illinois Hospital Association COMPdata database. The outcome as determined by in-hospital mortality was analyzed according to intervention type (open vs EVAR) and indication (elective repair vs ruptured AAA). Data were stratified by age, gender, and hospital type (university vs community setting) and then analyzed using both univariate (chi 2 , t tests) and multivariate (stepwise logistic regression) techniques. RESULTS: Between 1995 and 2003, 14,517 patients underwent AAA repair (85% for elective and 15% for ruptured AAA). The average age was 71.4 +/- 7.9 years, and 76% were men. For elective cases, open repair was performed in 86% and EVAR in 14%; and for ruptured cases, open repair in 97% and EVAR in 3%. Elective EVAR was associated with lower in-hospital mortality compared with open repair regardless of age. No differences were observed with age after either type of repair for a ruptured aneurysm. Men had a lower in-hospital mortality compared with women for open repair of both elective and ruptured aneurysms. For EVAR, the mortality of an elective repair was lower in men, but there was no difference after a ruptured AAA. In men, the difference in mortality between elective open repair and EVAR was significant; the type of institution did not influence outcome. Patients >80 years of age had a higher mortality after open repair for both elective and ruptured AAA and after EVAR of a ruptured AAA. The average length of stay was 9.9 days for open elective repair, 13.1 days after open repair of a ruptured AAA, and 3.6 days for EVAR. The independent predictors of higher in-hospital mortality were female gender, age >80 years, diagnosis (ruptured vs open), and procedure (open vs EVAR). The year of the procedure and type of hospital (university vs community) were not predictive of outcome. CONCLUSIONS: EVAR has had a significant impact on AAA management in Illinois over a relatively short time period. In this population-based review, EVAR was associated with a significantly decreased in-hospital mortality and length of stay. Octogenarians had higher mortality after both types of repair, with the exception of elective EVAR.

Inferior vena cava endograft to control surgically inaccessible hemorrhage.

Open surgical repair of retrohepatic inferior vena cava (IVC) injuries can be technically difficult, usually requiring extensive hepatic mobilization and associated with significant morbidity. We report a case of uncontrolled hemorrhage from the retrohepatic inferior vena cava (IVC), which occurred during attempted resection of a large retroperitoneal leiomyosarcoma, and was successfully managed using an endoluminal stent-graft. This case demonstrates that endoluminal grafts can be successfully applied to control life-threatening hemorrhage arising from lesions in the retrohepatic IVC that are otherwise extremely difficult or inaccessible to direct surgical repair.