Intramolecular locking and coumarin insertion: a stepwise approach for TADF design.

Three novel TADF (thermally activated delayed fluorescence) emitters based on the well-studied Qx-Ph-DMAC fluorophore are designed and synthesized. The photophysical properties of these materials are studied from a theoretical and experimental point of view, demonstrating the cumulative effects of multiple small modifications that combine to afford significantly improved TADF performance. First, an extra phenyl ring is added to the acceptor part of Qx-Ph-DMAC to increase the conjugation length, resulting in BQx-Ph-DMAC, which acts as an intermediate molecular structure. Next, an electron-deficient coumarin unit is incorporated to fortify the electron accepting ability, affording ChromPy-Ph-DMAC with red-shifted emission. Finally, the conjugated system is further enlarged by 'locking' the molecular structure, generating DBChromQx-DMAC with further red-shifted emission. The addition of the coumarin unit significantly impacts the charge-transfer excited state energy levels with little effect on the locally excited states, resulting in a decrease of the singlet-triplet energy gap. As a result, the two coumarin-based emitters show considerably improved TADF performance in 1 w/w% zeonex films when compared to the initial Qx-Ph-DMAC structure. 'Locking' the molecular structure further lowers the singlet-triplet energy gap, resulting in more efficient reverse intersystem crossing and increasing the contribution of TADF to the total emission.

A nationwide assessment comparing nonelective open with minimally invasive complex colorectal procedures.

AIM: The use of minimally invasive colorectal surgery has increased greatly for both benign and malignant disease. Studies evaluating complex procedures have been largely limited to elective indications. We aimed to compare the outcome of a laparoscopic with an open transverse (TC) and total abdominal colectomy (TAC) in the nonelective setting. METHOD: Comparative analysis was made using the Nationwide Inpatient Sample (2008-11) of patients undergoing a nonelective TC or TAC identified by ICD-9-CM procedure codes. The risk-adjusted 30-day outcome was assessed using regression modelling accounting for patient characteristics, comorbidity and surgical procedure. RESULTS: We identified 7261 admissions including 818 laparoscopic and 6443 open procedures. The mean age of the population was 65 ± 17 years and patients in the laparoscopic group were younger (56 ± 20 vs. 66 ± 17 years; P < 0.05). The rate of a single complication was lower in the laparoscopic group (26% vs. 38%; P < 0.01), but this did not remain significant following a logistic regression analysis. Mortality was significantly lower in the laparoscopic group (3.1% vs. 17%; P < 0.01) and this remained true after adjusting for covariates (OR = 0.62; P < 0.05). Laparoscopic cases were associated with a shorter median length of stay (10 vs. 13 days; P < 0.01) and hospital charge ($75,758 vs. $98,833; P < 0.01). CONCLUSION: A nonelective laparoscopic TC or TAC is associated with an equivalent complication rate and lower mortality compared with an open operation. The results should encourage surgeons with the appropriate skills to consider a laparoscopic approach for nonelective pathology requiring a complex colectomy.

System-based factors influencing intraoperative decision-making in rectal cancer by surgeons: an international assessment.

AIM: Sound surgical judgement is the goal of training and experience; however, system-based factors may also colour selection of options by a surgeon. We analysed potential organizational characteristics that might influence rectal cancer decision-making by an experienced surgeon. METHOD: One hundred and seventy-three international centres treating rectal cancer were invited to participate in a survey assessment of key treatment options for patients undergoing curative rectal-cancer surgery. The key organizational characteristics were analysed using multivariate methods for association with intra-operative surgical decision-making. RESULTS: The response rate was 71% (123 centres). Sphincter-saving surgery was more likely to be performed at university hospitals (OR=3.63, P=0.01) and by high-caseload surgeons (OR=2.77 P=0.05). A diverting stoma was performed more frequently in departments with clinical audits (OR=3.06, P=0.02), and a diverting stoma with coloanal anastomosis was more likely in European centres (OR=4.14, P=0.004). One-stage surgery was less likely where there was assessment by a multidisciplinary team (OR=0.24, P=0.02). Multivariate analysis showed that university hospital, clinical audit, European centre, multidisciplinary team and high caseload significantly impacted on surgical decision-making. CONCLUSION: Treatment variance of rectal cancer surgeons appears to be significantly influenced by organizational characteristics and complex team-based decision-making. System-based factors may need to be considered as a source of outcome variation that may impact on quality metrics.

Combined experimental-theoretical NMR study on 2,5-bis(5-aryl-3-hexylthiophen-2-yl)-thiazolo[5,4-d]thiazole derivatives for printable electronics.

Four 2,5-bis(5-aryl-3-hexylthiophen-2-yl)thiazolo[5,4-d]thiazole derivatives have been synthesized and thoroughly characterized. The extended aromatic core of the molecules was designed to enhance the charge transport characteristics, and solubilizing hexyl side chains were introduced on the thiophene subunits to enable possible integration of these semiconducting small molecules in printable electronics. Complete elucidation of the chemical structures by detailed one-dimensional/two-dimensional NMR spectroscopy is described, providing interesting input for chemical shift prediction software as well, because limited experimental data on these types of compounds are currently available. Furthermore, theoretical calculations have assisted experimental observations--giving support for the chemical shift assignment and providing a springboard for future screening and predictions--demonstrating the benefits of a coordinated theoretical-experimental approach.

Density functional theory-based simulations of sum frequency generation spectra involving methyl stretching vibrations: effect of the molecular model on the deduced molecular orientation and comparison with an analytical approach.

The knowledge of the first hyperpolarizability tensor elements of molecular groups is crucial for a quantitative interpretation of the sum frequency generation (SFG) activity of thin organic films at interfaces. Here, the SFG response of the terminal methyl group of a dodecanethiol (DDT) monolayer has been interpreted on the basis of calculations performed at the density functional theory (DFT) level of approximation. In particular, DFT calculations have been carried out on three classes of models for the aliphatic chains. The first class of models consists of aliphatic chains, containing from 3 to 12 carbon atoms, in which only one methyl group can freely vibrate, while the rest of the chain is frozen by a strong overweight of its C and H atoms. This enables us to localize the probed vibrational modes on the methyl group. In the second class, only one methyl group is frozen, while the entire remaining chain is allowed to vibrate. This enables us to analyse the influence of the aliphatic chain on the methyl stretching vibrations. Finally, the dodecanethiol (DDT) molecule is considered, for which the effects of two dielectrics, i.e. n-hexane and n-dodecane, are investigated. Moreover, DDT calculations are also carried out by using different exchange-correlation (XC) functionals in order to assess the DFT approximations. Using the DFT IR vectors and Raman tensors, the SFG spectrum of DDT has been simulated and the orientation of the methyl group has then been deduced and compared with that obtained using an analytical approach based on a bond additivity model. This analysis shows that when using DFT molecular properties, the predicted orientation of the terminal methyl group tends to converge as a function of the alkyl chain length and that the effects of the chain as well as of the dielectric environment are small. Instead, a more significant difference is observed when comparing the DFT-based results with those obtained from the analytical approach, thus indicating the importance of a quantum chemical description of the hyperpolarizability tensor elements of the methyl group.

Randomized clinical trial comparing the cost and effectiveness of bipolar vessel sealers versus clips and vascular staplers for laparoscopic colorectal resection.

BACKGROUND: The widespread use of laparoscopy has resulted in a variety of instruments being used routinely for vascular control. This randomized controlled trial evaluated the cost-effectiveness of bipolar vessel sealer (BVS) compared with clips and vascular stapler (CVS) in straight laparoscopic colorectal resection. METHODS: Patients scheduled for elective colorectal resection, including benign and malignant diseases, were randomized to either BVS or CVS for vascular control. Patients whose operation was converted to an open approach before pedicle ligation were excluded. The primary endpoints were duration of operation, including time taken to control vascular pedicles, and cost of disposable instruments for vascular control. RESULTS: Of 114 patients randomized to BVS (60 patients) or CVS (54), 14 did not receive the allocated vascular control device, leaving 55 and 45 respectively for analysis. The BVS reduced the time spent for vascular control by a mean of 6·9 min (P = 0·031) and reduced the cost of disposable instruments for vascular control by US $ 80·7 per patient (P = 0·043). For total colectomy, the BVS reduced the operating time by 103·6 min (P = 0·023) and the time taken for vascular control by 16·8 min (P = 0·022). For left colectomy, it decreased the time to vascular control by 9·3 min (P = 0·021). In multivariable analysis, the cost of disposable instruments for vascular control was independently reduced by randomization to BVS, type of procedure, female sex and estimated blood loss. The mean cost reduction was $ 88·2 for left colectomy (P = 0·037), $ 377·7 (P = 0·005) for total colectomy and $ 366·9 (P = 0·012) for proctectomy. Conversely, use of the BVS increased the cost of instruments used for vascular control in right colectomy by $ 92·6 (P = 0·012). CONCLUSION: BVS devices are expedient and cost-efficient in proctectomy, left and total colectomy procedures.

Fingerprints for structural defects in poly(thienylene vinylene) (PTV): a joint theoretical-experimental NMR study on model molecules.

In the field of plastic electronics, low band gap conjugated polymers like poly(thienylene vinylene) (PTV) and its derivatives are a promising class of materials that can be obtained with high molecular weight via the so-called dithiocarbamate precursor route. We have performed a joint experimental-theoretical study of the full NMR chemical shift assignment in a series of thiophene-based model compounds, which aims at (i) benchmarking the quantum-chemical calculations against experiments, (ii) identifying the signature of possible structural defects that can appear during the polymerization of PTV's, namely head-to-head and tail-to-tail defects, and (iii) defining a criterion regarding regioregularity.

Single-incision vs straight laparoscopic segmental colectomy: a case-controlled study.

PURPOSE: Single-incision laparoscopic surgery is gaining momentum in general surgery but it is essentially unstudied for laparoscopic colectomy. The aim of our study was to compare outcomes for single-incision laparoscopic colectomy with laparoscopic-assisted colectomy. METHODS: Patients undergoing laparoscopic colectomy were prospectively entered into an institutional review board-approved database. Those that underwent single-incision laparoscopic colectomy were case matched for sex, age, disease, surgery, body mass index, previous surgeries, and surgeon with patients undergoing LAC. RESULTS: Twenty-nine single-incision laparoscopic segmental colectomies were performed for polyps (4), adenocarcinoma (12), diverticulitis (6), and Crohn's disease (7) and were case matched to laparoscopic-assisted colectomy for the same indications. Mean body mass index was 28.8 ± 3 kg/m². Operative time was longer for single-incision laparoscopic colectomy (134.4 ± 40 vs 103.8 ± 54 min; P = .0002). Four single-incision laparoscopic colectomies were converted to LAC requiring either one extra port (2) or 2 extra ports (2), and there was one conversion to laparotomy. Extraction scar length (millimeters) was similar (38 ± 6.0 vs 45 ± 6.2; P = .746). Postoperative morbidity (5/29 vs 7/29; P = .284) and length of stay (day) (3.7 ± 1.1 vs 3.9 ± 1.1; P = .445) were similar between groups. CONCLUSIONS: Single-incision laparoscopic colectomy is feasible and safe but takes more time than laparoscopic-assisted colectomy. Although results approximate those for laparoscopic-assisted colectomy, an additional learning curve is involved, and extra incisions are sometimes required. Single-incision laparoscopic colectomy requires further prospective validation so that the cost of the device can be justified by an improved clinical outcome.

Single incision laparoscopic total colectomy and proctocolectomy for benign disease: initial experience.

AIM: This paper presents our initial experience of single incision laparoscopic total colectomy and proctocolectomy. METHOD: Four female patients (mean age 35.5 years; mean body mass index 24.7 kg/m(2) ) underwent total colectomy with end ileostomy (n = 2) and proctocolectomy with stapled ileum pouch-anal (n = 1) and rectal (n = 1) anastomosis with loop ileostomy, for benign disease, using a single-incision laparoscopic approach. The single port was placed at the umbilicus or the ileostomy site. Specimen extraction was through the port site. RESULTS: Operative procedures were performed with a mean operative time of 212 min, mean blood loss of 30 ml and no intraoperative complication. No additional abdominal ports were required. A postoperative ileus (n = 1) on day three resolved spontaneously and the. mean hospital stay was 4.5 days. CONCLUSION: Single-incision laparoscopic total colectomy or proctocolectomy is feasible for benign disease in selected patients.

Assessment of comparative skills between hand-assisted and straight laparoscopic colorectal training on an augmented reality simulator.

PURPOSE: The aim of this study was to compare skills sets during a hand-assisted and straight laparoscopic colectomy on an augmented reality simulator. METHODS: Twenty-nine surgeons, assigned randomly in 2 groups, performed laparoscopic sigmoid colectomies on a simulator: group A (n = 15) performed hand-assisted then straight procedures; group B (n = 14) performed straight then hand-assisted procedures. Groups were compared according to prior laparoscopic colorectal experience, performance (time, instrument path length, and instrument velocity changes), technical skills, and operative error. RESULTS: Prior laparoscopic colorectal experience was similar in both groups. Both groups had better performances with the hand-assisted approach, although technical skill scores were similar between approaches. The error rate was higher with the hand-assisted approach in group A, but similar between both approaches in group B. CONCLUSIONS: These data define the metrics of performance for hand-assisted and straight laparoscopic colectomy on an augmented reality simulator. The improved scores with the hand-assisted approach suggest that with this simulator a hand-assisted model may be technically easier to perform, although it is associated with increased intraoperative errors.

Tobacco smoking in seven Latin American cities: the CARMELA study.

OBJECTIVE: This study aimed to explore tobacco smoking in seven major cities of Latin America. METHODS: The Cardiovascular Risk Factor Multiple Evaluation in Latin America (CARMELA) study is a cross-sectional epidemiological study of 11 550 adults between 25 and 64 years old in Barquisimeto, Venezuela; Bogota, Colombia; Buenos Aires, Argentina; Lima, Peru; Mexico City, Mexico; Quito, Ecuador; and Santiago, Chile. Tobacco smoking, including cigarettes, cigars and pipes, was surveyed among other cardiovascular risk factors. RESULTS: Santiago and Buenos Aires had the highest smoking prevalence (45.4% and 38.6%, respectively); male and female rates were similar. In other cities, men smoked more than women, most markedly in Quito (49.4% of men vs 10.5% of women). Peak male smoking prevalence occurred among the youngest two age groups (25-34 and 35-44 years old). Men and women of Buenos Aires smoked the highest number of cigarettes per day on average (15.7 and 12.4, respectively). Men initiated regular smoking earlier than women in each city (ranges 13.7-20.0 years vs 14.2-21.1 years, respectively). Exposure to secondhand tobacco smoke at workplace for more than 5 h per day was higher in Barquisimeto (28.7%), Buenos Aires (26.8%) and Santiago (21.5%). The highest prevalence of former smokers was found among men in Buenos Aires, Santiago and Lima (30.0%, 26.8% and 26.0% respectively). CONCLUSIONS: Smoking prevalence was high in the seven CARMELA cities, although patterns of smoking varied among cities. A major health and economic burden is inevitable in urban Latin America unless effective comprehensive tobacco control measures recommended by the World Health Organisation Framework Convention on Tobacco Control are implemented.

Single incision laparoscopic colectomy: technical aspects, feasibility, and expected benefits.

Background. This paper studied technical aspects and feasibility of single incision laparoscopic colectomy (SILC). Methods. Bibliographic search was carried out up to October 2009 including original articles, case reports, and technical notes. Assessed criteria were techniques, operative time, scar length, conversion, complications, and hospitalization duration. Results. The review analyzed seventeen SILCs by seven surgical teams. A single port system was used by four teams. No team used the same laparoscope. Two teams used two laparoscopes. All teams used curved instruments. SILC time was 116 +/- 34 minutes. Final scar was longer than port incision (31 +/- 7 versus 24 +/- 8 mm; P = .036). No conversion was reported. The only complication was a bacteremia. Hospitalization was 5 +/- 2 days. Conclusion. SILC is feasible. A single incision around the umbilical scar represents cosmetic progress. Comparative studies are needed to assess potential abdominal wall and recovery benefits to justify the increased cost of SILC.

Tissue apposition system: new technology to minimize surgery for endoscopically unresectable colonic polyps.

OBJECTIVE: This is the first clinical series using the Tissue Apposition System (TAS) device in a feasibility study of polypectomy as an alternative to laparoscopic colectomy (LC) for endoscopically unresectable polyps. TAS is a novel T-tag system for endoscopic placement of sutures, facilitating closure of larger defects from advanced endoluminal or transluminal endoscopic procedures. Such novel instrumentation may reduce risk and accelerate recovery. METHODS: After institutional review board approval, patients with endoscopically unresectable polyps who would otherwise require LC were enrolled. The polyp site was visualized by colonoscopy and resected with laparoscopic assistance, using endoscopic mucosal resection (EMR) or submucosal dissection. After confirming benign disease by frozen section, the polypectomy site was closed by TAS under laparoscopic observation to avoid injury to surrounding structures. Follow-up colonoscopy was performed at 3 months. RESULTS: Seven patients were recruited (5 men; mean age, 66 years). Polyps were from 20 to 50 (mean, 30) mm in diameter; six were in the right colon, and three were on the mesenteric border of the bowel. All final pathology was benign. Mean EMR time was 29 min, mean time taken for TAS was 37 min, and mean total operative time was 199 min. Two TAS procedures required conversion to LC (one unresectable polyp and one device failure). Five TAS procedures were completed, with a mean hospital stay of 1.2 days, and no complications. Follow-up colonoscopy revealed healing without polyp recurrence in any case. One patient (initial 5-cm sigmoid polyp) developed a very mild clinically asymptomatic stricture in the sigmoid colon. CONCLUSIONS: This initial human experience demonstrates that TAS can be used safely in the colon under laparoscopic control. TAS permits safe closure of defects after endoscopic polypectomy of selected and otherwise unresectable polyps. Such technology may potentially avoid the need for LC and permit rapid recovery with short hospital stay.

High prevalence of diabetes and impaired fasting glucose in urban Latin America: the CARMELA Study.

AIMS: Cardiovascular risk is increased with glucose metabolism abnormalities. Prevalence data can support public health initiatives required to address this risk. The Cardiovascular Risk Factor Multiple Evaluation in Latin America (CARMELA) study was designed to estimate the prevalence of Type 2 diabetes, impaired fasting glucose and related risk factors in seven urban Latin American populations. METHODS: CARMELA was a cross-sectional, population-based study of 11 550 adults 25-64 years of age. With a multi-stage sample design of a probabilistic nature, approximately 1600 subjects were randomly selected in each city. RESULTS: Overall, the prevalence of diabetes was 7.0% (95% confidence intervals 6.5-7.6%). The prevalence of individuals with diabetes or impaired fasting glucose increased with increasing age. In the oldest age category, 55-64 years of age, prevalence of diabetes ranged from 9 to 22% and prevalence of impaired fasting glucose ranged from 3 to 6%. Only 16.3% of people with prior diagnosis of diabetes and who were receiving pharmacologic treatment, were in good glycaemic control (fasting glucose < 6.1 mmol/l). The prevalence of diabetes in individuals with abdominal obesity was approximately twofold higher. Participants with hypertension, elevated serum triglycerides and increased common carotid artery intima-media thickness were also more likely to have diabetes. CONCLUSIONS: The prevalence of diabetes and impaired fasting glucose is high in seven major Latin American cities; intervention is needed to avoid substantial medical and socio-economic consequences. CARMELA supports the associations of abdominal obesity, hypertension, elevated serum triglycerides and carotid intima-media thickness with diabetes.

Standardized algorithms for management of anastomotic leaks and related abdominal and pelvic abscesses after colorectal surgery.

BACKGROUND: The risk factors and incidence of anastomotic leak following colorectal surgery are well reported in the literature. However, the management of the multiple clinical scenarios that may be encountered has not been standardized. METHODS: The medical literature from 1973 to 2007 was reviewed using PubMed for papers relating to anastomotic leaks and abdominal abscess, with a specific emphasis on predisposing factors, prevention strategies, and treatment approaches. A six-round modified Delphi research method was utilized to find consensus among a group of expert colorectal surgeons and interventional radiologists regarding standardized management algorithms for anastomotic leaks. RESULTS: Management scenarios were divided into those for intraperitoneal anastomoses, extraperitoneal (low pelvic) anastomoses, and anastomoses with proximal diverting stomas. Management options were then based on the clinical presentation and radiographic findings and organized into three interconnected algorithms. CONCLUSIONS: This process was a useful first step toward establishing guidelines for the management of anastomotic leak.

Tracking oligodendrocytes during development and regeneration.

Over the past decade, advances in strategies to tag cells have opened new avenues for examining the development of myelin-forming glial cells and for monitoring transplanted cells in animal models of myelin insufficiency. The strategies for labelling glial cells have encompassed a range of genetic modifications as well as methods for directly attaching labels to cells. Genetically modified oligodendrocytes have been engineered to express enzymatic (e.g., beta-galactosidase, alkaline phosphatase), naturally fluorescent (e.g., green fluorescent protein), and antibiotic resistance (e.g., neomycin, zeomycin) reporters. Genes have been introduced in vivo and in vitro with viral or plasmid vectors to somatically label glial cells. To generate germ-line transmission of tagged oligodendrocytes, transgenic mice have been created both by direct injection into mouse fertilized eggs and by "knock-in" of reporters targetted to myelin gene loci in embryonic stem cells. Each experimental approach has advantages and limitations that need to be considered for individual applications. The availability of tagged glial cells has expanded our basic understanding of how oligodendrocytes are specified from stem cells and should continue to fill in the gaps in our understanding of how oligodendrocytes differentiate, myelinate, and maintain their myelin sheaths. Moreover, the ability to select oligodendrocytes by virtue of their acquired antibiotic resistance has provided an important new tool for isolating and purifying oligodendrocytes. Tagged glial cells have also been invaluable in evaluating cell transplant therapies in the nervous system. The tracking technologies that have driven these advances in glial cell biology are continuing to evolve and present new opportunities for examining oligodendrocytes in living systems. Microsc. Res. Tech. 52:766-777, 2001. Published 2001 Wiley-Liss, Inc.

Three-wave mixing in chiral liquids

Second-order nonlinear optical frequency conversion in isotropic systems is only dipole allowed for sum- and difference-frequency generation in chiral media. We develop a single-center chiral model of the three-wave mixing (sum-frequency generation) nonlinearity and estimate its magnitude. We also report results from ab initio calculations and from three- and four-wave mixing experiments in support of the theoretical estimates. We show that the second-order susceptibility in chiral liquids is much smaller than previously thought.

Proteolytic cleavage of ICAM-1 by human neutrophil elastase.

Human leukocyte elastase (HLE) participates in tissue destruction in a number of inflammatory disorders, including rheumatoid arthritis and cystic fibrosis. Since HLE has been shown to bind to Mac-1, and ICAM-1 plays a key role during the recruitment and the activation of leukocytes at inflamed sites, we investigated the capacity of HLE to cleave ICAM-1. Flow-cytometric analyses showed a dose-dependent cleavage of ICAM-1 by HLE on different human cell lines. The cleavage was completely inhibited by alpha1-antitrypsin, a natural HLE protease inhibitor. The ability of HLE to degrade ICAM-1 was further confirmed by electrophoretic analysis using a soluble form of ICAM-1 (D1-D5). Enzymatic removal of N-linked glycosylation did not significantly modulate ICAM-1 cleavage by HLE, while removal of sialic acid residues partially reduced the sensitivity of ICAM-1 to HLE. We further showed that sputum of cystic fibrosis patients contains high levels of HLE activity capable of cleavage of cell surface ICAM-1. The cleavage induced by incubation of cells with the sputum sample was totally inhibited by alpha1-antitrypsin and the specific peptidic HLE inhibitor N-methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone. Moreover, the cleavage of ICAM-1 was concomitant to that of CD4 at the surface of the same cell, at the same amplitude, and at all HLE concentrations. The capacity of HLE to modulate the expression of ICAM-1 on the surface of leukocytes by proteolytic cleavage brings support to the hypothesis that overproduction of HLE can cause severe immunologic lung disorders by affecting intercellular adhesion.