Thermochemistry and kinetics for 2-butanone-1-yl radical (CH2·C(═O)CH2CH3) reactions with O2.

Thermochemistry of reactants, intermediates, transition state structures, and products along with kinetics on the association of CH2·C(═O)CH2CH3 (2-butanone-1-yl) with O2 and dissociation of the peroxy adduct isomers are studied. Thermochemical properties are determined using ab initio (G3MP2B3 and G3) composite methods along with density functional theory (B3LYP/6-311g(d,p)). Entropy and heat capacity contributions versus temperature are determined from structures, vibration frequencies, and internal rotor potentials. The CH2·C(═O)CH2CH3 radical + O2 association results in a chemically activated peroxy radical with 27 kcal mol(-1) excess of energy. The chemically activated adduct can react to stabilized peroxy or hydroperoxide alkyl radical adducts, further react to lactones plus hydroxyl radical, or form olefinic ketones and a hydroperoxy radical. Kinetic parameters are determined from the G3 composite methods derived thermochemical parameters, and quantum Rice-Ramsperger-Kassel (QRRK) analysis to calculate k(E) with master equation analysis to evaluate falloff in the chemically activated and dissociation reactions. One new, not previously reported, peroxy chemistry reaction is presented. It has a low barrier path and involves a concerted reaction resulting in olefin formation, H2O elimination, and an alkoxy radical.

Screening of different metal oxide nanoparticles reveals selective toxicity and inflammatory potential of silica nanoparticles in lung epithelial cells and macrophages.

In cell culture studies, foetal calf serum (FCS) comprising numerous different proteins is added, which might coat the surface of engineered nanomaterials (ENMs) and thus could profoundly alter their biological activities. In this study, a panel of industrially most relevant metal oxide nanoparticles (NPs) was screened for toxic effects in A549 lung epithelial cells and RAW264.7 macrophages in the presence and absence of FCS. In medium without FCS amorphous SiO2-NPs were the most cytotoxic NPs and induced a significant pro-inflammatory response in both cell types. An increased anti-oxidative response after exposure to SiO2-NPs was, however, only observed in RAW264.7 macrophages. Furthermore, pre-coating of SiO2-NPs with FCS proteins or simply bovine serum albumin abrogated responses in A549 lung epithelial cells. Thus, the protein corona bound to the surface of SiO2-NPs suppresses their biological effects, an issue which needs to be more carefully considered for in vitro-in vivo extrapolations.

[Microsurgical reconstruction of the pelvic floor after pelvic exenteration. Reduced morbidity and improved quality of life by an interdisciplinary concept]. / Mikrochirurgische Beckenbodenrekonstruktion nach Exenteratio pelvis. Verminderte Morbidität und verbesserte Lebensqualität durch ein interdisziplinäres Konzept.

BACKGROUND: Pelvic exenteration for advanced or recurrent rectal cancer often results in complex defects associated with high complication rates and morbidity for the patients. The goal of therapy is therefore restoration of functional stability and adequate soft tissue coverage, thus enhancing the quality of life with limited life expectancy by an interdisciplinary approach. PATIENTS AND METHODS: We report on eight patients treated by combined interdisciplinary pelvic exenteration with resection of the sacrum and subsequent coverage of the pelvic floor defect with free latissimus dorsi muscle flaps. All patients were treated in two stages according to a pre-established therapeutic algorithm. First, an abdominal and transsacral pelvic exenenteration was performed with an ileostomy and ileum conduit system and the pelvic floor was closed with vicryl meshes. The open wound was optimized by vacuum-assisted closure (VAC) therapy before reconstruction of the pelvic floor was undertaken 10-12 days later with free latissimus dorsi musculocutaneous flaps either anastomosed to the lower or upper gluteal vessels or to an AV-loop using the saphenous vein as connection to the groin vessels. RESULTS: In all cases a sufficient and stable reconstruction of the pelvic floor could be achieved and no flap loss occurred. In three patients a minor wound dehiscence occurred, which could be closed by secondary suture. The time span between the free flap transfer and stable wound closure was 19-28 days. Later complications such as fistula formation and chronic wound infections were not observed. The survival of the patients ranged from 10-36 months. CONCLUSION: The present two-stage concept of pelvic floor reconstruction with free latissimus dorsi muscle flaps for wound closure after pelvic exenteration improves postoperative morbidity and mortality and increases the quality of life of the affected patients. A shortened period of open wound therapy brings additional economic benefits. Because of its anatomical features the free latissimus dorsi flap can be regarded as the method of choice of microsurgical reconstruction within an interdisciplinary concept after pelvic exenteration.

HERG1 gene expression as a specific tumor marker in colorectal tissues.

INTRODUCTION: Colorectal carcinomas exhibit a frequent recurrence after curative surgery, which may partially be due to histopathologically inconspicuous minimal residual disease. Reliable markers for tumor cells in colorectal tissue are still missing. Therefore, in this study we compared the predictive value of the putative tumor markers carcinoembryonic antigen (CEA), cytokeratin-19 (CK19) and cytokeratin-20 (CK20) to that of a novel marker, the human ether-a-go-go-related gene (HERG1) K(+) channel, a suggested regulator of tumor cell proliferation. MATERIALS AND METHODS: Using RT-PCR we studied HERG, CEA, CK19 and CK20 expression in colorectal carcinomas and non-carcinoma controls. HERG1 immunhistochemistry was performed in a total of 66 specimens, in colorectal carcinoma (n = 23), in matched histopathologically negative samples (n = 23) taken near the excision site from the same tumor patients and in healthy control biopsies (n = 20). In order to verify the relevance of HERG1 for tumor proliferation we studied the effect of HERG1 inhibition in the Colo-205 colon cancer carcinoma cell line using the MTT-assay. RESULTS: HERG1 was expressed in all tumor samples regardless of their stage and in adenomas larger than 0.4 cm, but absent in small adenomas, sigmadiverticulitis specimen and healthy histopathologically negative samples, except for one which developed a tumor recurrence. In contrast, CEA, CK19 and CK20 were absent in some tumors. The selective HERG1 inhibitor E-4031 dose-dependently impaired tumor growth in the proliferation assays. DISCUSSION: Our data indicate that HERG1, but not CEA, CK19 or CK20, is a highly sensitive and reliable tumor biomarker that may constitute a novel molecular target for tumor treatment.

Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures.

Point measurements of time-resolved LII signals have been performed in sooting premixed low pressure flames. Soot particle size distribution and gas temperature in these flames are known from independent measurements. This data is used to validate parameters of an improved LII model, where special emphasis is taken on the accurate modelling of mass and heat transfer rates. Using this model particle size distributions and gas temperatures can be estimated from time-resolved LII signals using non-linear regression. Standard numerical methods are applied. An experimental setup is presented, which allows measuring one-dimensional maps of particle size distribution and gas temperature. The technique is based on the one-dimensional and time-resolved detection of LII signals using a Streak camera.

Frequency of the Amsterdam criteria in a regional German cohort of patients with colorectal cancer.

Estimates of the colon cancer burden associated with hereditary nonpolyposis colorectal cancer (HNPCC) vary from less than 1 % to more than 5 %. Amsterdam criteria fulfilled within a kindred (classic Amsterdam and Amsterdam II criteria) are widely used to identify patients prone to HNPCC. The present study was initiated to assess the frequency of the Amsterdam criteria within a regional German cohort of 207 patients with a history of colorectal cancer (CRC). Data on individual and family cancer histories were available in 154 patients (73 women, 81 men; mean age at diagnosis 62.4 +/- 13.3 years). A total of 843 first degree relatives have been identified within the kindreds of whom 121 had verified cancers. In 28 of 154 families (18 %), at least one first degree relative of the index patient had CRC. With respect to a typical family history, five kindreds (3.2 %) were likely to suffer from HNPCC on a clinical basis (4 kindreds met the classic Amsterdam criteria and one kindred the Amsterdam II criteria). Testing for microsatellite instability could additionally be performed in 4 of 5 patients who met the Amsterdam criteria and revealed DNA instability in 3 cases. Moreover, a missense mutation of MSH2 (Gly965Asp) was detected in one patient with microsatellite instability. Based on the classic Amsterdam and Amsterdam II criteria approximately 3 % of a regional German cohort of patients with CRC are likely to suffer from HNPCC. However, the final diagnosis of HNPCC can only be established by detection of pathogenic germline mutations within the DNA mismatch repair genes.

[Video-laparoscopic placement of adjustable gastric banding (lap-band) in the treatment of morbid obesity. Preliminary results after 407 interventions]. / Aplicación de la bandeleta gástrica ajustable (lap-band) por videolaparoscopia en el tratamiento de la obesidad mórbida. Resultados preliminares tras 407 intervenciones.

INTRODUCTION: Morbid obesity is the most frequent nutritional disorder in developed countries. Bariatric surgery is one option for the definitive treatment of this disorder. We present 407 patients who underwent implantation of adjustable silicone gastric banding. Ninety-four percent of the patients were satisfied with the procedure and its results. MATERIAL AND METHOD: We performed a retrospective study in the Surgery Department of the Nordwestkrankenhaus teaching hospital of the University of Frankfurt. From April 1996 to January 2000 we performed laparoscopic placement of adjustable silicone gastric banding in 407 patients, using Kuzmak's technique. Mean body mass index was 49.1 and mean weight was 139.2 kg. We describe the patient selection method and provide a detailed description of the technique and its possible problems. RESULTS: There was no operative or postoperative mortality. None of the patients required conventional surgery. Mean operating time was 62 minutes (including operating times during the learning period). Mean hospital stay was 5 days. We performed 24 (5,89%) reinterventions: 11 for displacement, 2 for erosion, 4 for infection of the reservoir, 2 due to review of the reservoir to prevent penetration and 4 due to dilatations of the pouch (changing the banding from a retrogastric to a retroesophageal position); one patient requested removal of the banding. Follow-up was performed at months 1, 6, 9 and 12. Mean weight loss was 28 kg at 6 months and 54 kg at 1 year. Mean weight loss in patients followed-up for 2 years was 58 kg. A total of 94.9% of the patients were satisfied with the procedure. CONCLUSIONS: Laparoscopic implantation of adjustable gastric banding (Lap-Band) combines the aims of conventional gastroplasty with the advantages of laparoscopic surgery in terms of postoperative morbidity and minimal invasiveness.

A prospective randomized trial of different laparoscopic gastric banding techniques for morbid obesity.

BACKGROUND: Slippage of the stomach is the most common postoperative complication after laparoscopic adjustable silicone gastric banding (LASGB) for morbid obesity. Retrogastric placement (RGP) of the band through the lesser sac can cause posterior slippage Incomplete suturing often is responsible for anterior slippage. A randomized prospective study was constructed to determine whether laparoscopic esophagogastric placement (EGP) is associated with a lower incidence of postoperative slippage and pouch dilation than RGP. METHODS: Morbid obese patients presenting for LASGB were randomized to undergo either an EGP (n = 50) or an RGP (n = 51). Patients were blinded to which procedure they underwent, and follow-up date were obtained by a blinded independent investigator. Standardized clinical and radiologic controls were used to assess pouch enlargement and slippage. RESULTS: Operating time was similar for the two procedures (54.5 min for EGP vs 58 min for RGP). There was no significant difference in postoperative weight loss (34 kg after EGP vs 37 kg after RGP within 12 months), esophagus dilation, or postoperative quality of life. There were two postoperative slippages and one pouch dilation in the RGP group and no postoperative complication in the EGP group. CONCLUSIONS: The placement of a LAP-BAND adjustable gastric banding system by the EGP technique is safe and results in a lower frequency of postoperative complications than its placement by the RGP technique. Clear anatomic landmarks are a benefit to education and to the learning curve for LASGB.

Flamelet modeling of NO formation in laminar and turbulent diffusion flames.

The applicability of the laminar flamelet concept for the formation and destruction of nitric oxides in laminar and turbulent diffusion flames has been studied. In a first step, temperatures and species concentrations in an axisymmetric laminar diffusion flame have been calculated (i) by solving the detailed conservation equations and (ii) by applying the laminar flamelet concept. The main purpose of this step was the identification of differences between results from both approaches. It turned out that for highly temperature sensitive or relatively slow chemical processes, the inclusion of the full range of the prevailing scalar dissipation rates plays a major role for the calculated species concentrations. This behavior is obvious from the concept of the laminar flamelet model, where the scalar dissipation rate can be discussed in terms of the reciprocal of a residence time for attaining chemical equilibrium. In a second step, flamelet modeling of NOx formation was extended to a turbulent hydrogen diffusion flame. In both the steps, the flow fields of the flames were calculated by solving the Navier-Stokes equations in axisymmetric formulation using the SIMPLER algorithm. For the turbulent flow, Favre-averaged equations have been used and turbulence was modeled with the standard k-epsilon model including a correction term for axisymmetric systems. The averaging of the species concentrations was accomplished with presumed shape probability density functions (pdfs). The pdf of the mixture fraction was described with a beta-function whereas that of the scalar dissipation rate was assumed to be log-normal. Buoyancy effects have been taken into account. The calculated temperatures and concentrations were compared with data from different experiments.

A detailed numerical study of the evolution of soot particle size distributions in laminar premixed flames.

In this work, two numerical techniques, viz. the method of moments and a discrete h-p-Galerkin method, have been applied for numerical simulation of soot formation in a laminar premixed acetylene/oxygen/argon flame. From the evolution of the PAH and the soot particle size distributions, new insight into the different processes of soot formation is provided. For this, the single submodels have been examined with respect to their influence on the PAH and the soot particle size distributions. The particle inception step was studied in detail by comparing the simulated PAH size distributions with experimental results. Additionally, an estimation of the interaction energy of layered PAH dimers was performed by quantum chemical calculations. From these results, some evidence for the particle inception model employing coalescence of PAH molecules has been found. The numerical results for the gas phase chemical species, the particle number densities and volume fractions of soot as well as for the soot particle size distributions are compared with experimental data. Thereby, the consistency of the entire model is demonstrated.

[A new technique for laparoscopic placement of the adjustable gastric band (LAP-band) for preventing slippage]. / Eine neue Technik zur laparoskopischen Plazierung des steuerbaren Magenbandes (LAP-Band) zur Vermeidung eines Slippage.

BACKGROUND: Slippage (SP) of the stomach is the most common postoperative complication after laparoscopic adjustable silicone gastric banding (LAS-GB) for morbid obesity. METHODS AND PATIENTS: A randomized prospective study was constructed in order to determine whether laparoscopic placement behind the cardia (RKP) is associated with a lower incidence of postoperative SP and pouch dilation than after a retrogastric placement (RGP) of the LAP band using a common technique. Morbidly obese patients presenting for LASGB were randomized to undergo either an RKP (n = 50) or an RGP (n = 51). RESULTS: There were three postoperative SP and three pouch dilations in the RGP group versus no postoperative complication in the RKP group. CONCLUSIONS: The placement of LAP band by the RKP technique is safe and followed by a lower frequency of postoperative complications than with the RGP technique. Clear anatomical landmarks are a benefit to the education and learning curve of LASGB.

Resistance modulation in CHO cells by R-verapamil and bile salts is associated with physical and chemical changes in the cell membrane.

OBJECTIVES: Changes in multidrug resistance by resistance modifiers such as R-verapamil cause changes in fluidity of the cell membrane. The extent to which these changes involve structural alterations in membrane lipids has been investigated in CHO cells. METHODS: Sensitive (AUXB1) and resistant (CH(R)C5) chinese hamster ovary cells (CHO) were grown in culture. Incubations were carried out with R-verapamil (0-10 microM) or the membrane perturbing agents tauro-cheno-deoxycholate (0-1.6 mM, TCDC) and tauro-urso-deoxycholate (0-3.5mM, TUDC). Cell membrane fluidity was determined by electron-paramagnetic resonance spectroscopy and membrane lipids by HPLC and TLC. RESULTS: The resistant CH(R)C5 subline had a higher cell membrane order (lower fluidity, S = 0.7234) in the interface region of the cell membrane than sensitive AUXB1 cells (S = 0.6984) determined using EPR. The MDR-modulator R-verapamil and TCDC, but not TUDC, lowered cell membrane order in a concentration-dependent manner and increased membrane fluidity of the resistant CH(R)C5 subline. TCDC and R-verapamil were without effect on the cell membrane fluidity of AUXB1 cells. These changes were accompanied by alterations in the fatty acid composition of the plasma membrane. Untreated sensitive AUXB1 cells had higher levels of unsaturated fatty acids than resistant CH(R)C5 cells. In CH(R)C5 cells, R-verapamil increased the content of poly-unsaturated fatty acids and TCDC, but not TUDC, increased the content of mono-unsaturated fatty acids. CONCLUSIONS: The results demonstrate that resistance modifiers such as verapamil may influence cytostatic drug action by producing structural changes to lipid domains in the plasma membrane.

Treatment of morbid obesity using an adjustable gastric banding system.

Morbid obesity is a serious disease that is responsible for several co-morbid conditions. Patients with a body mass index of over 40 kg/m2 will require surgical intervention if a dietary program fails. In the US, patients who are morbidly obese number approximately 8 million. At present, three conventional operations, with acceptable early and late complication rates, are performed most frequently worldwide: vertical gastroplasty (VRG), vertical banded gastroplasty (VBG), and gastric bypass (GB). In this article, we describe our experience with the LAP-BAND technique, and in particular with the new LAP-BAND adjustable gastric banding system (LAGB), which further reduces postoperative complications and reoperations.

Preparation of extremely obese patients for laparoscopic gastric banding by gastric-balloon therapy.

BACKGROUND: In super, super obese patients (body mass index [BMI] >60), especially those with extreme intra-abdominal fat deposition, the technical difficulties in laparoscopic procedures increase. The purpose of this study was to evaluate whether gastric balloon therapy (GBT) can improve the operative conditions for laparoscopic adjustable gastric banding (LAGB) in extremely obese patients. MATERIALS AND METHODS: From April 1995 to August 1998, 196 LAGBs were performed. In 15 patients (7 female and 8 male), median age 38.8 years (range 17-54), who had been selected as suitable candidates for bariatric surgery, preoperative GBT was studied. Fourteen patients were extremely obese (BMI 60.2 kg/m2 [range 58-72]). One 17-year-old boy with BMI 46.6 kg/m2 was also treated. The Bioenterics Intragastric Balloon (BIB) was used. The placement, the volume modification, and the removal of the BIB were performed endoscopically. Close follow-up was possible in 14 patients. After balloon removal, 13 patients underwent LAGB. RESULTS: In 14 of 15 cases, GBT was successful. There was only one ballon dysfunction. The mean weight loss was 18.1 kg, and the median duration of balloon therapy was 16.8 weeks. After balloon removal, body weight started to increase. CONCLUSIONS: In our experience, the gastric balloon can improve the conditions for laparoscopic surgery in super and in super, super obese patients. There was no conversion to open surgery. The effect of weight loss is much less than immediately after LAGB. However, after failure of all conservative treatments to reduce the preoperative body weight, the GBT seems to be the last possibility.

Laparoscopic gastric banding for morbid obesity.

Morbid obesity is a serious disease that is responsible for several comorbid conditions. Body mass indices > 40 require surgical procedures if diet programs fail. Laparoscopic adjustable gastric banding (LAGB), a more recently introduced gastric restrictive procedure, was designed to be a minimally invasive and reversible operation. 184 patients (164 women, 20 men) with a mean body mass index of 47.8 kg/m2 (range 36-79) were operated on. All patients had been excessively overweight for > 5 years. Each patient was given general anesthesia, and an adjustable LAP-BAND was implanted laparoscopically. The pouch size was 15 ml in all cases; and 3-4 sutures were placed to prevent dislocation. The conversion rate was 0%. The median operating time was 65 min (range 45-190). The mortality was 0%. The mean hospital stay was 5 days (range 4-6). The mean excess weight loss was 16% in 4 weeks, 23% in 3 months, 31% in 6 months, 58% in 1 year, and 87% in 2 years. The patient satisfaction index was 97.6%. Once a surgeon has acquired the necessary laparoscopic surgical experience, LAGB is a feasible, safe, and simple procedure with excellent postoperative results. LAGB does not permanently modify the anatomy of the stomach and maintains the natural continuity of the alimentary tract, while at the same time ensuring a steady weight reduction in morbidly obese patients. The fact that the gastric band can be applied laparoscopically is a significant advantage in this group of high-risk patients, who have less pain, faster postoperative recovery, more rapid return to normal activities, fewer wound infections, fewer hernia problems, and better cosmetic results. The rate of postoperative complications is approximately 9%. In 1.1% of patients, erosion occurred, and in 2.2%, slippage of the band. The rate of port-related complications was 3.2%. Reoperations were necessary in 6.4% of the patients.

Quality-of-life outcome after laparoscopic adjustable gastric banding for morbid obesity.

BACKGROUND: The definition of success and failure of a bariatric procedure should include weight loss as well as improvement of comorbidity and quality-of-life (QoL) assessment. QoL measures changes in physical, functional, mental, and social health in order to evaluate benefits of new programs and interventions. MATERIAL AND METHODS: From April 1995 until March 1999, 287 patients underwent laparoscopic adjustable silicone gastric banding (LASGB) at Northwest Hospital Frankfurt a.M. (Germany). In this study, 100 of 287 patients (preoperative mean BMI 48.3 kg/m2; mean age 35.2 years) with a follow-up >18 month were evaluated. All patients underwent anonymous questionnaire (26 questions with a maximum score of 60) about different aspects of QoL outcome after LSAGB. RESULTS: In this study, 4 of 100 patients refused to give an answer to the QoL questions. Therefore 96 patients were evaluated. The QoL auto-evaluation of the patients shows that QoL generally improved after surgery in 92%. Using the scoring system, 44% of patients have excellent, 52% good, and only 4% bad results. The 4 patients who refused had to be classified as failure. General acceptance of LSAGB is wide, but gastrointestinal side effects are recognizable in more than 78% of operated patients. Successful weight loss is followed by an improvement of comorbidities. CONCLUSIONS: Safe, effective bariatric procedures increase the quality of life in morbidly obese patients markedly. Bariatric surgeons are committed to support and help their patients until they reach a new quality of life after obesity surgery.

[Management and therapy of postoperative complications after "gastric banding" for morbid obesity]. / Management und Therapie von postoperativen Komplikationen nach "gastric banding" wegen morbider Adipositas.

Laparoscopic gastric banding has become a common procedure in bariatric surgery. Early as well as late complications are, in comparison to conventional techniques, rare. Complications arising from the operative technique are: perforation, early pouch dilatation, gastric slippage, infections of the port and the band, erosion and defects of the band tube. Insufficient weight loss and late pouch dilatation arise from unsatisfactory compliance on the part of the patient. In 7.5% of 146 cases, reoperations were necessary. Obstruction of the pouch stoma and a slippage resulted in total food intolerance. After radiologic diagnosis the band system should be deflated first and a naso-gastric tube applied. If this does not result in the pouch collapsing, a revision operation is needed.

[Laparoscopic gastric banding for treatment of morbid obesity]. / Laparoskopisches Gastric Banding zur Behandlung morbiditärer Adipositas.

The laparoscopic implantation of the LAP-BAND is a minimal invasive technique in obese patients. The effectiveness is comparable to that of gastroplasty. In all 186 patients were treated laparoscopically. The conversion rate was 0%. There were no death. In 0.5% there were intraoperative complications; 3% complications were caused by the port system; and 4% of the late postoperative complications were related to the LAP-BAND (pouch dilatation, slippage).

[Trocar complications and technical aspects for prevention in laparoscopic hernia operation (TAPP and TPP)]. / Trokarkomplikationen und technische Aspekte ihrer Vermeidung bei der laparoskopischen Hernienoperation (TAPP und TPP).

By comparing trocar-related complications in laparoscopic hernia repair in two series, we can demonstrate a lower rate of complications if blunt trocars were used. In 238 procedures using cutting trocars, we registered 2 major complications and 9% of local hematoma.

[Laparoscopic staging of gastrointestinal tumors]. / Laparoskopisches Staging bei gastrointestinalen Tumoren.

Laparoscopic staging was carried out in 28 cases with carcinomas of the distal esophagus, cardia, stomach or pancreas. The intention was first to rule out peritoneal carcinomatosis and secondly to see, whether RO-resection would be possible, mainly for the reason of therapeutic splitting. The diagnostic accuracy can be raised to 95% using laparoscopic ultrasound, exploration of the lesser sac of the peritoneum and tissue sampling in combination with preoperative endoscopy and radiography. In 39.3% of the investigated patients the staging must be corrected after laparoscopic staging compared with the preoperative findings. 35.7% of the patients did not need explorative laparotomy.