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Small anionic nickel clusters with ethanol are investigated with a combination of mass-selective infrared photodissociation spectroscopy in a molecular beam and density functional theory simulations at the BLYP/6-311g(d,p) and TPSSh/def2-TZVPP level. In this context, the O-H stretching vibration of the ethanol is analyzed to obtain information about the structural motif, the geometry of the metal core, and the spin state of the clusters. For the [Ni2(EtOH)]- and [Ni3(EtOH)]- clusters, we assign quartet states of motifs with a hydrogen bond from the ethanol to the linear nickel core. The aggregation of a further ethanol molecule, yielding the [Ni3(EtOH)2]- cluster, results in the formation of a cooperative hydrogen bond network between the nickel core and the two ethanol molecules.
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In order to evaluate the impact of various intervention strategies on Plasmodium vivax dynamics in low endemicity settings without significant seasonal pattern, we introduce a simple mathematical model that can be easily adapted to reported case numbers similar to that collected by surveillance systems in various countries. The model includes case management, vector control, mass drug administration and reactive case detection interventions and is implemented in both deterministic and stochastic frameworks. It is available as an R package to enable users to calibrate and simulate it with their own data. Although we only illustrate its use on fictitious data, by simulating and comparing the impact of various intervention combinations on malaria risk and burden, this model could be a useful tool for strategic planning, implementation and resource mobilization.
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Malária , Plasmodium vivax , Humanos , Malária/tratamento farmacológico , Malária/epidemiologia , Administração Massiva de MedicamentosRESUMO
BACKGROUND: Based on excellent outcomes from high-volume centres, laparoscopic liver resection is increasingly being adopted into nationwide practice which typically includes low-medium volume centres. It is unknown how the use and outcome of laparoscopic liver resection compare between high-volume centres and low-medium volume centres. This study aimed to compare use and outcome of laparoscopic liver resection in three leading European high-volume centres and nationwide practice in the Netherlands. METHOD: An international, retrospective multicentre cohort study including data from three European high-volume centres (Oslo, Southampton and Milan) and all 20 centres in the Netherlands performing laparoscopic liver resection (low-medium volume practice) from January 2011 to December 2016. A high-volume centre is defined as a centre performing >50 laparoscopic liver resections per year. Patients were retrospectively stratified into low, moderate- and high-risk Southampton difficulty score groups. RESULTS: A total of 2425 patients were included (1540 high-volume; 885 low-medium volume). The median annual proportion of laparoscopic liver resection was 42.9 per cent in high-volume centres and 7.2 per cent in low-medium volume centres. Patients in the high-volume centres had a lower conversion rate (7.4 versus 13.1 per cent; P < 0.001) with less intraoperative incidents (9.3 versus 14.6 per cent; P = 0.002) as compared to low-medium volume centres. Whereas postoperative morbidity and mortality rates were similar in the two groups, a lower reintervention rate (5.1 versus 7.2 per cent; P = 0.034) and a shorter postoperative hospital stay (3 versus 5 days; P < 0.001) were observed in the high-volume centres as compared to the low-medium volume centres. In each Southampton difficulty score group, the conversion rate was lower and hospital stay shorter in high-volume centres. The rate of intraoperative incidents did not differ in the low-risk group, whilst in the moderate-risk and high-risk groups this rate was lower in high-volume centres (absolute difference 6.7 and 14.2 per cent; all P < 0.004). CONCLUSION: High-volume expert centres had a sixfold higher use of laparoscopic liver resection, less conversions, and shorter hospital stay, as compared to a nationwide low-medium volume practice. Stratification into Southampton difficulty score risk groups identified some differences but largely outcomes appeared better for high-volume centres in each risk group.
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Carcinoma Hepatocelular/cirurgia , Hepatectomia/métodos , Hospitais com Alto Volume de Atendimentos/estatística & dados numéricos , Laparoscopia/métodos , Neoplasias Hepáticas/cirurgia , Complicações Pós-Operatórias/epidemiologia , Pontuação de Propensão , Idoso , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Estudos Retrospectivos , Fatores de RiscoRESUMO
We report on a detailed multi-spectroscopic analysis of the structures and internal dynamics of diphenylether and its aggregates with up to three water molecules by employing molecular beam experiments. The application of stimulated Raman/UV and IR/UV double resonance methods as well as chirped-pulse Fourier transform microwave spectroscopy in combination with quantum-chemical computations yield the energetically preferred monomer and cluster geometries. Furthermore, the complex internal dynamics of the diphenylether monomer and the one-water clusters are analysed. In the cluster with three water molecules, water forms a cyclic structure similar to the isolated water trimer. The interactions ruling the structures of the higher-order water clusters are a combination of the ones identified for the two monohydrate isomers, with dispersion being a decisive contribution for systems that have a delicate energetic balance between different hydrogen-bonded arrangements of similar energy.
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BACKGROUND: Dutch guidelines indicate that treatment of pancreatic head and periampullary malignancies should be started within 3 weeks of the multidisciplinary team (MDT) meeting. This study aimed to assess the impact of time to surgery on oncological outcomes. METHODS: This was a retrospective population-based cohort study of patients with pancreatic head and periampullary malignancies included in the Netherlands Cancer Registry. Patients scheduled for pancreatoduodenectomy and who were discussed in an MDT meeting from May 2012 to December 2016 were eligible. Time to surgery was defined as days between the final preoperative MDT meeting and surgery, categorized in tertiles (short interval, 18 days or less; intermediate, 19-32 days; long, 33 days or more). Oncological outcomes included overall survival, resection rate and R0 resection rate. RESULTS: A total of 2027 patients were included, of whom 677, 665 and 685 had a short, intermediate and long time interval to surgery respectively. Median time to surgery was 25 (i.q.r. 14-36) days. Longer time to surgery was not associated with overall survival (hazard ratio 0·99, 95 per cent c.i. 0·87 to 1·13; P = 0·929), resection rate (relative risk (RR) 0·96, 95 per cent c.i. 0·91 to 1·01; P = 0·091) or R0 resection rate (RR 1·01, 0·94 to 1·09; P = 0·733). Patients with pancreatic ductal adenocarcinoma and a long time interval had a lower resection rate (RR 0·92, 0·85 to 0·99; P = 0·029). DISCUSSION: A longer time interval between the last MDT meeting and pancreatoduodenectomy did not decrease overall survival.
ANTECEDENTES: Las guías holandesas señalan que el inicio del tratamiento de los cánceres de cabeza de páncreas o periampulares se realice durante las tres semanas posteriores a la reunión del equipo multidisciplinar. Este estudio tuvo como objetivo evaluar la repercusión del tiempo transcurrido hasta la cirugía en los resultados oncológicos. MÉTODOS: Se trataba de un estudio de cohortes retrospectivo de base poblacional de pacientes con tumores pancreáticos de cabeza y periampulares a partir del registro de cáncer holandés. Se incluyeron los pacientes programados para duodenopancreatectomía cefálica discutidos en una reunión de equipo multidisciplinario entre mayo de 2012 y diciembre de 2016. El tiempo hasta la cirugía se definió como los días transcurridos entre la reunión final del equipo multidisciplinar y la cirugía, clasificándose en terciles (corto ≤ 18 días; intermedio 19-32 días; largo ≥ 33 días). Los resultados oncológicos analizados fueron la supervivencia global, la tasa de resección y la tasa de resección R0. RESULTADOS: Se incluyeron 2.027 pacientes, de los que 677, 665 y 685 correspondieron a los terciles de intervalo corto, intermedio y largo, respectivamente. La mediana del tiempo hasta la cirugía fue de 25 días (rango intercuartílico 14-36). La existencia de un intervalo de tiempo largo hasta la cirugía no se asociaba con la supervivencia global (cociente de riesgos instantáneos, hazard ratio, HR 0,99; i.c. del 95% 0,87-1,13; P = 0,93), la tasa de resección (riesgo relativo, RR 0,96; i.c. del 95% 0,91-1,01; P = 0,09) o la tasa de resección R0 (RR 1,01; i.c. del 95% 0,94-1,09; P = 0,73). Los pacientes con adenocarcinoma ductal pancreático y mayor intervalo tuvieron una tasa de resección más baja (RR 0,92; i.c. del 95%: 0,85-0,99; P = 0,03). CONCLUSIÓN: Un mayor intervalo de tiempo entre la última reunión del equipo multidisciplinar y la duodenopancreatectomía cefálica no disminuyó la supervivencia global.
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Carcinoma Ductal Pancreático/cirurgia , Neoplasias Pancreáticas/cirurgia , Pancreaticoduodenectomia/mortalidade , Equipe de Assistência ao Paciente , Tempo para o Tratamento , Idoso , Carcinoma Ductal Pancreático/patologia , Feminino , Fidelidade a Diretrizes , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Neoplasias Pancreáticas/patologia , Estudos Retrospectivos , Resultado do TratamentoRESUMO
The structural preferences within a series of dibenzofuran-solvent complexes have been investigated by electronic, vibrational, and rotational spectroscopic methods probing supersonic jet expansions. The experimental study is accompanied by a detailed theoretical analysis including dispersion-corrected density functional theory, symmetry adapted perturbation theory, as well as coupled cluster approaches. The complementary, multi-spectroscopic results reveal a preferred OHO structure for the smallest complex of dibenzofuran-water, whereas for the methanol complex an OHπ isomer is simultaneously observed. For the largest complex, dibenzofuran-tert-butyl alcohol, only a π-bound structure is found. These comprehensive investigations show that a completely inverse trend regarding the docking preference is observed by comparing the present results with the ones for analogous diphenyl ether complexes. This can be rationalized on the basis of the planarity/non-planarity and rigidity/flexibility of the different systems, providing valuable insight into the interplay between different non-covalent interactions. This analysis is a further step towards a quantitative description of very delicate energetic balances with the overall goal of yielding reliable structural predictions for non-covalently bound systems.
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This multicentre retrospective cohort study included 447 patients with Hinchey Ib and II diverticular abscesses, who were treated with antibiotics, with or without percutaneous drainage. Abscesses of 3 and 5 cm in size were at higher risk of short-term treatment failure and emergency surgery respectively. Initial non-surgical treatment of Hinchey Ib and II diverticular abscesses was comparable between patients treated with antibiotics only and those who underwent percutaneous drainage in combination with antibiotics, with regard to short- and long-term outcomes. Most do not need drainage.
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Abscesso Abdominal/tratamento farmacológico , Abscesso Abdominal/cirurgia , Colectomia/métodos , Doença Diverticular do Colo/tratamento farmacológico , Doença Diverticular do Colo/cirurgia , Abscesso Abdominal/diagnóstico , Adulto , Antibacterianos/uso terapêutico , Estudos de Coortes , Doença Diverticular do Colo/diagnóstico , Drenagem/métodos , Feminino , Seguimentos , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Países Baixos , Modelos de Riscos Proporcionais , Recidiva , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Falha de Tratamento , Resultado do TratamentoRESUMO
AIM: Laparoscopic peritoneal lavage has increasingly been investigated as a promising alternative to sigmoidectomy for perforated diverticulitis with purulent peritonitis. Most studies only reported outcomes up to 12 months. Therefore, the objective of this study was to evaluate long-term outcomes of patients treated with laparoscopic lavage. METHODS: Between 2008 and 2010, 38 patients treated with laparoscopic lavage for perforated diverticulitis in 10 Dutch teaching hospitals were included. Long-term follow-up data on patient outcomes, e.g. diverticulitis recurrence, reoperations and readmissions, were collected retrospectively. The characteristics of patients with recurrent diverticulitis or complications requiring surgery or leading to death, categorized as 'overall complicated outcome', were compared with patients who developed no complications or complications not requiring surgery. RESULTS: The median follow-up was 46 months (interquartile range 7-77), during which 17 episodes of recurrent diverticulitis (seven complicated) in 12 patients (32%) occurred. Twelve patients (32%) required additional surgery with a total of 29 procedures. Fifteen patients (39%) had a total of 50 readmissions. Of initially successfully treated patients (n = 31), 12 (31%) had recurrent diverticulitis or other complications. At 90 days, 32 (84%) patients were alive without undergoing a sigmoidectomy. However, seven (22%) of these patients eventually had a sigmoidectomy after 90 days. Diverticulitis-related events occurred up to 6 years after the index procedure. CONCLUSION: Long-term diverticulitis recurrence, re-intervention and readmission rates after laparoscopic lavage were high. A complicated outcome was also seen in patients who had initially been treated successfully with laparoscopic lavage with relevant events occurring up to 6 years after initial surgery.
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Diverticulite/terapia , Perfuração Intestinal/terapia , Laparoscopia/métodos , Lavagem Peritoneal/métodos , Peritonite/terapia , Idoso , Diverticulite/complicações , Feminino , Seguimentos , Humanos , Perfuração Intestinal/complicações , Masculino , Pessoa de Meia-Idade , Readmissão do Paciente/estatística & dados numéricos , Peritonite/etiologia , Recidiva , Estudos Retrospectivos , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: Combined laparoscopic resection of liver metastases and colorectal cancer (LLCR) may hold benefits for selected patients but could increase complication rates. Previous studies have compared LLCR with liver resection alone. Propensity score-matched studies comparing LLCR with laparoscopic colorectal cancer resection (LCR) alone have not been performed. METHODS: A multicenter, case-matched study was performed comparing LLCR (2009-2016, 4 centers) with LCR alone (2009-2016, 2 centers). Patients were matched based on propensity scores in a 1:1 ratio. Propensity scores were calculated with the following preoperative variables: age, sex, ASA grade, neoadjuvant radiotherapy, type of colorectal resection and T and N stage of the primary tumor. Outcomes were compared using paired tests. RESULTS: Out of 1020 LCR and 64 LLCR procedures, 122 (2 × 61) patients could be matched. All 61 laparoscopic liver resections were minor hepatectomies, mostly because of a solitary liver metastasis (n = 44, 69%) of small size (≤ 3 cm) (n = 50, 78%). LLCR was associated with a modest increase in operative time [206 (166-308) vs. 197 (148-231) min, p = 0.057] and blood loss [200 (100-700) vs. 75 (5-200) ml, p = 0.011]. The rate of Clavien-Dindo grade 3 or higher complications [9 (15%) vs. 13 (21%), p = 0.418], anastomotic leakage [5 (8%) vs. 4 (7%), p = 1.0], conversion rate [3 (5%) vs. 5 (8%), p = 0.687] and 30-day mortality [0 vs. 1 (2%), p = 1.0] did not differ between LLCR and LCR. CONCLUSION: In selected patients requiring minor hepatectomy, LLCR can be safely performed without increasing the risk of postoperative morbidity compared to LCR alone.
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Neoplasias Colorretais/cirurgia , Hepatectomia/métodos , Laparoscopia/métodos , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/cirurgia , Idoso , Neoplasias Colorretais/patologia , Conversão para Cirurgia Aberta , Feminino , Hepatectomia/efeitos adversos , Mortalidade Hospitalar , Humanos , Laparoscopia/efeitos adversos , Masculino , Análise por Pareamento , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Duração da Cirurgia , Complicações Pós-Operatórias , Pontuação de PropensãoRESUMO
By reacting 1,2-diketones and ortho- diphenylphosphinoyl aniline in the presence of zinc(ii) as a templating agent, cationic zinc(ii) complexes of novel phosphine oxide functionalized 1,4-diaza-1,3-butadiene ligands are acessible. Herein the zinc(ii) site is bound to all four donor atoms of the ligand. Depending on the flexibility of the 1,4-diaza-1,3-butadiene backbone, the bonds to zinc(ii) from the 1,4-diaza-1,3-butadiene donors can be broken. Reaction with oxalate cleaves the zinc(ii) coordination completely and makes accessible the free ligands possessing orthogonal (N,N: soft; O,O: hard) sets of donor sites. This allows for the specific coordination of soft and hard Lewis acids and thus for the generation of heterobimetallic complexes, here exemplarily shown for the combination of palladium(ii) (soft) and zinc(ii) (hard) centres.
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Understanding subtle aspects of photophysical behavior is the key to design and synthesize new and improved luminescent materials. We contribute to this with an in-depth photophysical characterization of the binuclear copper complex Cu(i)-NHetPHOS-tris-m-tolylphosphine (1), a member of a recently established emitter class for ultra-efficient, printed organic light-emitting diodes (OLEDs). To this end we studied 1 in solution and in solid form, i.e. neat film and KBr-pellet, by means of femtosecond time-resolved transient absorption/reflectivity, time-correlated single photon counting (TCSPC), and nanosecond time-resolved step-scan FTIR spectroscopy. Using these methods, we explore the photoinduced dynamics from ultrafast Franck-Condon state deactivation until the decay of the luminescent states. Upon photoexcitation, we observed multiexponential dynamics in both solution (e.g. acetonitrile 0.8 ps, 59 ps, 3 ns, 11-13 ns) and in solid state (e.g. neat film 0.3 ps, 35 ps, 670 ps, 0.5-1 µs, 3.5-4.5 µs) with four to five time-constants that significantly depend on the type of sample. Quantum chemical calculations at the DFT level in combination with step-scan vibrational spectroscopy provided structural information about the electronic ground state S0 and the lowest lying excited state T1, and show that the latter is populated within 1 µs after photoexcitation. We found thermally activated delayed fluorescence (TADF) for this complex, which has been suggested to be the cause for its high efficiency in printed OLED devices. The results suggest that non-radiative processes, lowering the luminescence quantum yield in solution, are active on the ns to µs timescale.
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Cyclic peptides represent a large class of substances that occur in nature with important biological and medical functions. Synthetic cyclic peptides are used as artificial receptors due to a series of advantages over conventional receptors. In order to optimize their binding abilities, investigations of their intrinsic structural properties especially with regard to the influence of different amino acid residues are fundamental. Here we report the structural analysis of two synthetic cyclic tetrapeptides cyclo[l-Tyr(Me)-d-Pro-l-Ala-d-Pro] (CPAla) and cyclo[l-Tyr(Me)-d-Pro-l-Glu(Me)-d-Pro] (CPGlu) in a molecular beam by means of combined IR/UV spectroscopic techniques. Structural assignments were achieved by comparing experimentally obtained vibrations and harmonically calculated frequencies including dispersion corrections (B3LYP-D3/TZVP). The investigated cyclic peptides contain an arrangement of an amino acid sequence which is no longer symmetric compared to the former investigations of the cyclo[l-Tyr(Me)-d-Pro]2 peptide. It turns out that all investigated compounds prefer conformations stabilized by two internal hydrogen bonds. In the case of CPGlu containing a flexible side chain with a terminal hydrogen bond acceptor an additional structure was observed in which a hydrogen bond between the terminal carboxylate group and a ring NH group is formed.
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Aminoácidos/química , Peptídeos Cíclicos/química , Sequência de Aminoácidos , Ligação de Hidrogênio , Ligação Proteica , Estrutura Secundária de Proteína , Análise EspectralRESUMO
BACKGROUND: Rectal cancer surgery is accompanied with high morbidity and poor long term functional outcome. Screening programs have shown a shift towards more early staged cancers. Patients with early rectal cancer can potentially benefit significantly from rectal preserving therapy. For the earliest stage cancers, local excision is sufficient when the risk of lymph node disease and subsequent recurrence is below 5 %. However, the majority of early cancers are associated with an intermediate risk of lymph node involvement (5-20 %) suggesting that local excision alone is not sufficient, while completion radical surgery, which is currently standard of care, could be a substantial overtreatment for this group of patients. METHODS/STUDY DESIGN: In this multicentre randomised trial, patients with an intermediate risk T1-2 rectal cancer, that has been locally excised using an endoluminal technique, will be randomized between adjuvant chemo-radiotherapylimited to the mesorectum and standard completion total mesorectal excision (TME). To strictly monitor the risk of locoregional recurrence in the experimental arm and enable early salvage surgery, there will be additional follow up with frequent MRI and endoscopy. The primary outcome of the study is three-year local recurrence rate. Secondary outcomes are morbidity, disease free and overall survival, stoma rate, functional outcomes, health related quality of life and costs. The design is a non inferiority study with a total sample size of 302 patients. DISCUSSION: The results of the TESAR trial will potentially demonstrate that adjuvant chemoradiotherapy is an oncological safe treatment option in patients who are confronted with the difficult clinical dilemma of a radically removed intermediate risk early rectal cancer by polypectomy or transanal surgery that is conventionally treated with subsequent radical surgery. Preserving the rectum using adjuvant radiotherapy is expected to significantly improve morbidity, function and quality of life if compared to completion TME surgery. TRIAL REGISTRATION: NCT02371304 , registration date: February 2015.
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Quimiorradioterapia Adjuvante , Colectomia , Neoplasias Retais/terapia , Projetos de Pesquisa , HumanosRESUMO
In this paper we present the first investigations on an isolated linear depsipetide CyCO-Gly-Lac-NH-PhOMe (cyclohexylcarbonyl-glycine-lactate-2-anisidine abbreviated as MOC) in a molecular beam experiment. Depsipeptides are a special subclass of peptides which contain at least one ester bond replacing a peptide bond. This leads to a different folding behavior and a different biological activity compared to a "normal" peptide. In order to analyze the folding of an isolated depsipeptide on a molecular level a variety of combined IR/UV methods including IR/IR/UV experiments are applied to MOC. Three different isomers are identified in combination with DFT calculations using the hybrid functional B3LYP-D3 with a TZVP basis set. The most stable structure shows a tweezer-like arrangement between the aromatic chromophore and the aliphatic cyclohexyl ring. A characteristic feature of this structure is that it is stabilized by dispersion interactions resulting from CH/π interactions. If dispersion is not taken into account this structural arrangement is no longer a minimum on the potential energy surface indicating the importance of dispersion interactions.
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BACKGROUND: At least a third of patients with a colorectal carcinoma who are candidate for surgery, are anaemic preoperatively. Preoperative anaemia is associated with increased morbidity and mortality. In general practice, little attention is paid to these anaemic patients. Some will have oral iron prescribed others not. The waiting period prior to elective colorectal surgery could be used to optimize a patients' physiological status. The aim of this study is to determine the efficacy of preoperative intravenous iron supplementation in comparison with the standard preoperative oral supplementation in anaemic patients with colorectal cancer. METHODS/DESIGN: In this multicentre randomized controlled trial, patients with an M0-staged colorectal carcinoma who are scheduled for curative resection and with a proven iron deficiency anaemia are eligible for inclusion. Main exclusion criteria are palliative surgery, metastatic disease, neoadjuvant chemoradiotherapy (5 × 5 Gy = no exclusion) and the use of Recombinant Human Erythropoietin within three months before inclusion or a blood transfusion within a month before inclusion. Primary endpoint is the percentage of patients that achieve normalisation of the haemoglobin level between the start of the treatment and the day of admission for surgery. This study is a superiority trial, hypothesizing a greater proportion of patients achieving the primary endpoint in favour of iron infusion compared to oral supplementation. A total of 198 patients will be randomized to either ferric(III)carboxymaltose infusion in the intervention arm or ferrofumarate in the control arm. This study will be performed in ten centres nationwide and one centre in Ireland. DISCUSSION: This is the first randomized controlled trial to determine the efficacy of preoperative iron supplementation in exclusively anaemic patients with a colorectal carcinoma. Our trial hypotheses a more profound haemoglobin increase with intravenous iron which may contribute to a superior optimisation of the patient's condition and possibly a decrease in postoperative morbidity. TRIAL REGISTRATION: ClincalTrials.gov: NCT02243735 .
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Anemia Ferropriva/tratamento farmacológico , Neoplasias Colorretais/cirurgia , Compostos Férricos/administração & dosagem , Compostos Ferrosos/administração & dosagem , Fumaratos/administração & dosagem , Hematínicos/administração & dosagem , Maltose/análogos & derivados , Cuidados Pré-Operatórios/métodos , Administração Oral , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anemia Ferropriva/etiologia , Protocolos Clínicos , Neoplasias Colorretais/complicações , Suplementos Nutricionais , Feminino , Compostos Férricos/uso terapêutico , Compostos Ferrosos/uso terapêutico , Fumaratos/uso terapêutico , Hematínicos/uso terapêutico , Humanos , Infusões Intravenosas , Masculino , Maltose/administração & dosagem , Maltose/uso terapêutico , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto JovemRESUMO
This paper presents a combined spectroscopic and theoretical analysis of a trinuclear [Pd3{Si(mt(Me))3}2] complex (mt(Me) = methimazole) which has been demonstrated to be a potential catalyst for coupling reactions. It is a highly symmetric model system (D3 in the electronic ground state) for the investigation of electronic states and the structure of polynuclear transition metal complexes. Different time-resolved IR spectroscopic methods covering the femtosecond up to the microsecond range as well as density functional computations are performed to unravel the structure and character of this complex in the electronically excited state. These are the first time-resolved IR studies on a trinuclear Pd complex. Based on the interplay between the computational results and those from the IR studies a (3)A state is identified as the lowest lying triplet state which has C2 symmetry.
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The first molecular beam investigations on a coumarin dimer and clusters of a coumarin dimer with water both in the neutral (S0) and cationic (D0) electronic ground state are performed. The structure and structural changes due to ionization of the isolated 7-hydroxy-4-methylcoumarin dimer (7H4MC)2 as well as its mono- and dihydrate (7H4MC)2(H2O)1-2 are analyzed by applying combined IR/UV spectroscopy compared with density functional theory calculations. In case of the neutral dimer of 7H4MC a doubly hydrogen-bonded structure is formed. This doubly hydrogen-bonded arrangement opens to a singly hydrogen-bonded structure in the ion presenting a rearrangement reaction within an isolated dimer. By attaching one or two water molecules to the neutral 7H4MC dimer water is inserted into the hydrogen bonds. In contrast to the non-hydrated species this general binding motif with water in a bridging function does not change via ionization but especially for the dihydrate the spatial arrangement of the two 7H4MC units changes strengthening the interaction between the aromatic chromophores. The presented analyses illustrate the strong dependence of binding motifs as a function of successive hydration and charge including a rearrangement reaction.
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Cumarínicos/química , Raios Infravermelhos , Análise Espectral , Raios Ultravioleta , Água/química , Dimerização , Temperatura Alta , Ligação de Hidrogênio , HidroxilaçãoRESUMO
In this paper the excited state proton transfer (ESPT) of isolated 3-hydroxychromone (3-HC), the prototype of the flavonols, is investigated for the first time by combined IR/UV spectroscopy in molecular beam experiments. The IR/UV investigations are performed both for the electronically excited and electronic ground state indicating a spectral overlap of transitions of the 3-HC monomer and clusters with water in the electronic ground state, whereas in the excited state only the IR frequencies of the proton-transferred monomer structure are observed. Due to the loss of isomer and species selectivity with respect to the UV excitations IR/IR techniques are applied in order to figure out the assignment of the vibrational transitions in the S0 state. In this context the quadruple resonance IR/UV/IR/UV technique (originally developed to distinguish different isomers in the electronically excited state) could be applied to identify the OH stretching vibration of the monomer in the electronic ground state. In agreement with calculations the OH stretching frequency differs significantly from the corresponding values of substituted hydroxychromones.
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Cromonas/química , Prótons , Teoria Quântica , Estrutura Molecular , Espectrofotometria Infravermelho , Espectrofotometria UltravioletaRESUMO
BACKGROUND: Short-term advantages to laparoscopic surgery are well described. This study compared medium- to long-term outcomes of a randomized clinical trial comparing laparoscopic and open colonic resection for cancer. METHODS: The case notes of patients included in the LAFA study (perioperative strategy in colonic surgery; LAparoscopy and/or FAst track multimodal management versus standard care) were reviewed 2-5 years after randomization for incisional hernia, adhesional small bowel obstruction (SBO), overall survival, cancer recurrence and quality of life (QoL). The laparoscopic and open groups were compared irrespective of fast-track or standard perioperative care. RESULTS: Data on incisional hernias, SBO, survival and recurrence were available for 399 of 400 patients: 208 laparoscopic and 191 open resections. These outcomes were corrected for duration of follow-up. Median follow-up was 3·4 (i.q.r. 2·6-4·4) years. Multivariable regression analysis showed that open resection was a risk factor for incisional hernia (odds ratio (OR) 2·44, 95 per cent confidence interval (c.i.) 1·12 to 5·26; P = 0·022) and SBO (OR 3·70, 1·07 to 12·50; P = 0·039). There were no differences in overall survival (hazard ratio 1·10, 95 per cent c.i. 0·67 to 1·80; P = 0·730) or in cumulative incidence of recurrence (P = 0·514) between the laparoscopic and open groups. There were no measured differences in QoL in 281 respondents (P > 0·350 for all scales). CONCLUSION: Laparoscopic colonic surgery led to fewer incisional hernia and adhesional SBO events. REGISTRATION NUMBER: NTR222 (http://www.trialregister.nl).