bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of power supply in the feasibility of Phaeodactylum tricornutum cultures
Authors: Brindley Alías C. , García‐Malea López M.C. , Acién Fernández F.G. , Ferníndez Sevilla J.M. , García Sánchez J.L. , Molina Grima E. 
Published: August 2004

AbstractThe influence of fluid‐dynamic conditions on the yield of Phaeodactylum tricornutum microalgal cultures was analyzed in two stages: first, the influence of air flow rate; second, the influence of using fluid‐moving pumps for recirculating the culture. With respect to the air flow rate, the yield of the cultures increased with the aeration rate up to values of 2.0 v/v/min, then stress was observed and the yield of the cultures decreased. With respect to the influence of mechanical power supply for liquid impulsion, three different types of pumps—centrifugal, pulse, and peristaltic—were essayed at different power supplies. The cultures were stressed for the three types of pumps essayed. For each pump, the higher the power supply the lower was the Fv/Fm value and the higher was the stress at which cells were exposed. The highest measured stress was when the culture was moved with the centrifugal pump. Despite measured stress, for all the experiments stable steady states were reached, thus indicating that cells reduced their yield but did not die, as was verified by cell viability measurements. It was observed that the increase of the power supply improved the frequency of light exposition thus enhancing the yield of the cultures. However, the higher the power supply, the lower the microeddy length scale; therefore, stress could appear. Data demonstrated that the microeddy length scale was always much higher than cell size and therefore the turbulence was not responsible for stress. Also, the mass transfer was discarded as responsible for yield reduction. It was concluded that the shear rate was the factor determining the existence of stress phenomena. The evaluation of these shear rates demonstrated that values above 30–80 s−1 damaged the cells strongly. These data were verified in an outdoor pilot‐scale tubular photobioreactor that was implemented with the same type of pumps, thus demonstrating the necessity to take into account this factor in the design and scale‐up of microalgal photobioreactors. © 2004 Wiley Periodicals, Inc.
Preparation, optimization, and structures of cross‐linked enzyme aggregates (CLEAs)
Authors: Schoevaart R. , Wolbers M.W. , Golubovic M. , Ottens M. , Kieboom A.P.G. , van Rantwijk F. , van der Wielen L.A.M. , Sheldon R.A. 
Published: August 2004

AbstractThe broad applicability of the cross‐linking of enzyme aggregates to the effective immobilisation of enzymes is demonstrated and the influence of many parameters on the properties of the resulting CLEAs is determined. The relative simplicity of the operation ideally lends itself to high‐throughput methodologies. The aggregation method was improved up to 100% activity yield for any enzyme. For the first time, the physical structures of CLEAs are elucidated. © 2004 Wiley Periodicals, Inc.
Generation of an α‐L‐rhamnosidase library and its application for the selective derhamnosylation of natural products
Authors: Monti Daniela , Pišvejcová Andrea , Křen Vladimír , Lama Marco , Riva Sergio 
Published: August 2004

AbstractA screening of 16 different fungal strains was performed under different cultivation conditions, using L‐rhamnose or L‐rhamnose‐containing flavonoid glycosides (rutin, hesperidin, and naringin) as specific inducers. No significant constitutive production of α‐L‐rhamnosidases was detected in noninduced cultures, while high levels of these glycosidase activities were obtained using different inducers. New species, so far unknown for the production of α‐L‐rhamnosidases, were identified.More than 30 different α‐L‐rhamnosidase samples were prepared by ammonium sulfate precipitation. Substrate specificity of this α‐L‐rhamnosidase library was tested with various L‐rhamnose‐containing natural compounds (flavonoids, terpenoids, and saponins). Most of the enzymatic preparations showed broad substrate specificity, and some of them were also acting on sterically hindered substrates (e.g., quercitrin). The screening of the library under different reaction conditions showed the coexistence, in the same preparation, of more than one α‐L‐rhamnosidase activities with different substrate specificity and different stability towards organic cosolvents.To exploit this enzymatic library for synthetic applications, the presence of contaminating α‐L‐arabinosidases and β‐D‐glucosidases was investigated. The latter enzymes were observed in several preparations, while α‐L‐arabinosidase content was generally quite low.The selective derhamnosylation of the saponin desglucoruscin was performed on a preparative scale. The enzyme obtained by rhamnose induction of the Aspergillus niger K2 CCIM strain showed high activity towards this substrate and negligible α‐L‐arabinosidase contamination. Therefore, it was chosen as a catalyst for the selective derhamnosylation reaction, which provided the desired product in 70% yield. © 2004 Wiley Periodicals, Inc.
Meta-analysis of randomized clinical trials of colorectal surgery with or without mechanical bowel preparation
Authors: Slim K , Vicaut E , Panis Y , Chipponi J 
Published: August 2004

AbstractBackgroundMechanical bowel preparation is used routinely before colorectal surgery, but some randomized clinical trials have suggested that it is of no benefit. This study assesses whether such bowel preparation may safely be omitted before elective colorectal surgery.MethodsA search of the literature was performed; the inclusion criteria were randomized clinical trials comparing bowel preparation with no preparation in colorectal surgery. The methodological quality of included trials was assessed. The primary outcome was anastomotic leakage; secondary outcomes were other septic complications. The meta-analysis was conducted using the Peto one-step method.ResultsEleven trials were retrieved, of which seven, containing 1454 patients, were included in the meta-analysis. There was no heterogeneity between the trials. Significantly more anastomotic leakage was found after mechanical bowel preparation (5·6 versus 3·2 per cent; odds ratio 1·75 (95 per cent confidence interval 1·05 to 2·90); P = 0·032). All other endpoints (wound infection, other septic complications and non-septic complications) also favoured the no-preparation regimen, but the differences were not statistically significant. Sensitivity analysis showed that these results were similar when trials of poor quality were excluded. Subgroup analysis showed that anastomotic leakage was significantly greater after bowel preparation with polyethylene glycol (PEG) compared with no preparation, but not after other types of preparation.ConclusionThere is good evidence to suggest that mechanical bowel preparation using PEG should be omitted before elective colorectal surgery. Other bowel preparations should be evaluated by further large randomized trials.
Prospective analysis of convalescence and early pain after uncomplicated laparoscopic fundoplication
Authors: Bisgaard T , Støckel M , Klarskov B , Kehlet H , Rosenberg J 
Published: August 2004

AbstractBackgroundThe aim of this study was to define factors that limit a short period of convalescence and to characterize the pain experienced after laparoscopic fundoplication.MethodsThis prospective study included 60 consecutive patients who underwent uncomplicated laparoscopic Nissen fundoplication for gastro-oesophageal reflux disease. Patients were recommended to convalesce for 2 days after operation. Duration of convalescence, dysphagia, fatigue, nausea, vomiting and different pain components were registered daily during the first week and on days 10 and 30 after fundoplication.ResultsThirty-nine patients took a median of 13 (range 3–41) days off work and 60 stayed away from recreational activity for a median of 4 (range 1–22) days. Pain, fatigue and plans made before operation were the main contributors to prolonged convalescence. Some 30–40 per cent of the patients reported moderate or severe dysphagia during the study period. Fatigue scores were significantly increased for 6 days after surgery (P &lt; 0 · 001). Visceral pain dominated over incisional and shoulder pain throughout the study. At day 30, 17 per cent of the patients reported moderate or severe visceral pain.ConclusionPain and dysphagia are significant problems after uncomplicated total laparoscopic fundoplication. The time taken off work and away from recreational activity exceeded the recommended 2 days of convalescence, justifying further efforts to optimize early clinical outcome after total laparoscopic fundoplication.
Surgical validation of unenhanced helical computed tomography in acute appendicitis
Authors: in't Hof K H , van Lankeren W , Krestin G P , Bonjer H J , Lange J F , Becking W B , Kazemier G 
Published: August 2004

Abstract

Background
Surgery for pain in the right lower quadrant of the abdomen remains a clinical dilemma. This prospective study assessed the accuracy of preoperative unenhanced helical computed tomography (CT) in the evaluation of patients with suspected acute appendicitis.

Methods
One hundred and three adult patients with suspected acute appendicitis underwent unenhanced helical CT of the abdomen. Subsequently, all patients underwent laparoscopic inspection of the abdominal cavity by a surgeon who was blinded to the diagnosis suggested by CT. Patients underwent appropriate surgical therapy accordingly. Follow-up was at least 6 weeks.

Results
Appendicitis was diagnosed by CT in 83 patients (80·6 per cent). Acute appendicitis was identified during laparoscopy in 87 patients (84·5 per cent). Prospective interpretation of CT images yielded a sensitivity of 95·4 per cent and a specificity of 100 per cent for the diagnosis of acute appendicitis. There were four false-negative scans. In 12 of 20 patients without signs of appendicitis on CT, the scan established the presence of other pathology. At operation no additional pathology was observed in this group and all other diagnoses proved to be correct.

Conclusion
Plain helical CT in patients with suspected acute appendicitis provides an accurate diagnosis without the disadvantages of contrast enhancement.
Polarity Effects on the Photophysics of Dendrimers with an Oligophenylenevinylene Core and Peripheral Fullerene Units
Authors: Gutierrez‐Nava Manuel , Accorsi Gianluca , Masson Patrick , Armaroli Nicola , Nierengarten Jean‐François 
Published: August 2004

AbstractHighly soluble dendritic branches with fullerene subunits at the periphery and a carboxylic acid function at the focal point have been prepared by a convergent approach. They have been attached to an oligophenylenevinylene (OPV) core bearing two alcohol functions to yield dendrimers with two, four or eight peripheral C60 groups. Their photophysical properties have been systematically investigated in solvents of increasing polarity; that is, toluene, dichloromethane, and benzonitrile. Ultrafast OPV→C60 singlet energy transfer takes place for the whole series of dendrimers, whatever the solvent. Electron transfer from the fullerene singlet is thermodynamically allowed in CH2Cl2 and benzonitrile, but not in apolar toluene. For a given solvent, the extent of electron transfer, signaled by the quenching of the fullerene fluorescence, is not the same along the series, despite the fact that identical electron transfer partners are present. By increasing the dendrimer size, electron transfer is progressively more difficult due to isolation of the central OPV core by the dendritic branches, which hampers solvent induced stabilization of charge separated couples. Compact structures of the hydrophobic dendrimers are favored in solvents of higher polarity. These structural effects are also able to rationalize the unexpected trends in singlet oxygen sensitization yields.
Influence of DNA Structure on the Reactivity of the Guanine Radical Cation
Authors: Gervasio Francesco Luigi , Laio Alessandro , Iannuzzi Marcella , Parrinello Michele 
Published: August 2004

AbstractOxidative damage of DNA via radical cation formation is a common cause of mutagenesis, cancer and of the physiological changes associated with aging. By using state‐of‐the‐art ab initio molecular dynamics simulations, we study the mechanism that guides the first steps of this process. In the mechanism proposed here, guanine, which among the bases has the lowest oxidation potential, and the phosphate backbone play a crucial role. We found that the rate limiting step is the water protolysis. We illuminate the role of the local environment in considerably lowering the barrier. Of particular relevance in this respect is the role of the phosphate backbone.
Retention of Configuration in the Nucleophilic Substitution Reactions of Some Nine‐Membered Ansa Derivatives of Cyclotriphosphazatriene
Authors: Beşli Serap , Coles Simon J. , Davies David B. , Hursthouse Michael B. , İbişoǧlu Hanife , Kılıç Adem , Shaw Robert A. 
Published: August 2004

AbstractX‐ray crystallographic evidence shows that nucleophilic substitution reactions of two different types of cyclophosphazene derivatives with relatively rigid nine‐membered ansa rings leads to the first demonstration of retention of configuration in these molecular systems.
Nanoscopic Fibrous Assemblies Made of Metallophthalocyanine‐Terminated Amphiphilic Polymers
Authors: Kimura Mutsumi , Ueki Hiroyuki , Ohta Kazuchika , Hanabusa Kenji , Shirai Hirofusa , Kobayashi Nagao 
Published: August 2004

AbstractAtom‐transfer radical polymerization (ATRP) of acrylates from the initiator‐modified zinc phthalocyanine yielded amphiphilic, phthalocyanine‐terminated polymers with a narrow molecular‐weight distribution. The disklike phthalocyanine moiety was incorporated into one end of the polymer chain. We investigated the aggregation behavior of phthalocyanine‐terminated polymers in solution and in the solid state by using UV‐visible, FT‐IR, differential scanning calorimetry (DSC), and temperature‐controlled powder X‐ray diffraction (XRD) measurements. Amphiphilic phthalocaynine‐terminated polymers that possess a poly[tri(ethylene glycol)methyl ether acrylate] chain aggregate in methanol to form a physical gel. Images from atomic force microscopy (AFM) and transmission electron microscopy (TEM) indicate that the physical gel contains a dense fibrous network structure, in which the zinc phthalocyanine groups were stacked into one‐dimensional columnar aggregates through intermolecular π–π interactions between the π‐conjugated phthalocyanines and through van der Waals interaction of alkyl chains.
The Efficient Synthesis of Morphinandienone Alkaloids by Using a Combination of Hypervalent Iodine(III) Reagent and Heteropoly Acid
Authors: Hamamoto Hiromi , Shiozaki Yukiko , Nambu Hisanori , Hata Kayoko , Tohma Hirofumi , Kita Yasuyuki 
Published: August 2004

AbstractThe non‐phenolic coupling reaction of benzyltetrahydroisoquinolines (laudanosine derivatives) by using a hypervalent iodine(III) reagent is described. In general, chemical oxidation of laudanosine gives glaucine. In contrast to general chemical oxidizing reagent systems, the novel use of reagent combination of phenyliodine bis(trifluoroacetate) (PIFA), and heteropoly acid (HPA) afforded morphinandienone alkaloids in excellent yields. In order to achieve the coupling reaction with simple reaction procedure, the use of HPA supported on silica gel instead of HPA was demonstrated and sufficient yield was exerted again. The present reagent system, PIFA/HPA, was also applied to the oxidation of other non‐phenolic benzyltetrahydroisoquinolines and the high yield conversion to morphinandienones was accomplished.
Final Elucidation of the Absolute Configuration of the Signal Metabolite Hormaomycin
Authors: Zlatopolskiy Boris D. , Loscha Karin , Alvermann Petra , Kozhushkov Sergei I. , Nikolaev Sergej V. , Zeeck Axel , de Meijere Armin 
Published: August 2004

AbstractThe complete absolute configuration of hormaomycin 1 a has been established by HPLC and HPLC/MS experiments with appropriately derivatized 4‐propylprolines, (2S,4S)‐6 and (2R,4R)‐6, as well as 4‐(Z)‐propenylprolines, cis‐5 and trans‐5, and also feeding experiments with enantiomerically pure samples of the deuterium‐labeled 3‐(2′‐nitrocyclopropyl)alanine, (2S)‐3,3‐[D2]15 and (2S)‐2,2′‐[D2]15, and 4‐(Z)‐propenylproline 2′,4‐[D2]‐(2S,4R)‐5. The latter five amino acids were prepared for the first time and allowed one to unequivocally assign the hitherto unknown absolute configurations of the last four stereocenters in hormaomycin 1 a. As a bonus, some new information about the biosynthesis of this molecule has also been gathered.
Nucleophilic De‐coordination and Electrophilic Regeneration of “Hemilabile” Pincer‐Type Complexes: Formation of Anionic Dialkyl, Diaryl, and Dihydride PtII Complexes Bearing No Stabilizing π‐Acceptors
Authors: Poverenov Elena , Gandelman Mark , Shimon Linda J. W. , Rozenberg Haim , Ben‐David Yehoshoa , Milstein David 
Published: August 2004

AbstractNovel anionic dialkyl, diaryl, and dihydride platinum(II) complexes based on the new “long‐arm” hemilabile PCN‐type ligand C6H4[CH2P(tBu)2](CH2)2N(CH3)2 with the general formula Li+[Pt(PCN)(R)2]− (R=Me (4), Ph (6) and H (9)) were prepared by reaction of [Pt(PCN)(R)] complexes (obtained from the corresponding chlorides) with an equivalent of RLi, as a result of the opening of the chelate ring. Alkylating agents based on other metals produce less stable products. These anionic d8 complexes are thermally stable although they bear no stabilizing π acceptors. They were characterized by 1H, 31P{1H}, 13C, and 7Li NMR spectroscopy; complex 9 was also characterized by single crystal X‐ray crystallography, showing that the Li + ion is coordinated to the nitrogen atom of the open amine arm and to the hydride ligand (trans to the P atom) of a neighboring molecule (HLi=2.15 Å), resulting in a dimeric structure. Complexes 4 and 9 exhibit high nucleophilic reactivity, upon which the pincer complex is regenerated. Reaction of 4 with water, methyl iodide, and iodobenzene resulted in the neutral complex [Pt(PCN)(CH3)] (3) and methane, ethane, or toluene, respectively. Labeling studies indicate that the reaction proceeds by direct electrophilic attack on the metal center, rather than attack on the alkyl ligand. The anionic dihydride complex 9 reacted with water and methyl iodide to yield [Pt(PCN)(H)] (8) and H2 or methane, respectively.
Enhancing Electrophilic Alkene Activation by Increasing the Positive Net Charge in Transition‐Metal Complexes and Application in Homogeneous Catalysis
Authors: Hahn Christine 
Published: August 2004

AbstractAmong a large variety of fine‐tuning parameters for homogeneous catalysts the net charge of transition‐metal complexes appear to be an interesting factor that considerably affects activation of substrates and catalytic activity in general. The electrophilicity of coordinated alkenes in transition‐metal complexes can be strongly enhanced by increasing the positive net charge, resulting in strong carbocationic properties. Theoretical and experimental studies have shown that the alkene in cationic complexes is kinetically and thermodynamically more activated towards nucleophilic addition than in neutral complexes. The concept of increasing the positive complex charge is thought to be useful for the development of new catalysts for reactions in which alkenes or other unsaturated substrates are involved.
Colitis in patients with breast carcinoma treated with taxane‐based chemotherapy
Authors: Li Zhiyong , Ibrahim Nuhad K. , Wathen Jay K. , Wang Michael , Mante Menchu Rosario P. , Valero Vicente , Theriault Richard , Buzdar Aman U. , Hortobagyi Gabriel N. 
Published: August 2004

AbstractBACKGROUNDColitis is a rare but serious gastrointestinal complication associated with taxane‐based chemotherapy in patients with cancer. The incidence, clinical presentation, and outcome of colitis in patients with breast carcinoma treated with taxane‐based chemotherapy is not known.METHODSThe authors searched their electronic database and identified patients with breast carcinoma who were treated with taxane‐based chemotherapy between January 1997 and December 1999. Patients diagnosed with colitis were identified and their presentation and clinical outcomes were analyzed.RESULTSDuring the study period, 1350 patients received taxane‐based chemotherapy. Sixty‐four patients were admitted to The University of Texas M. D. Anderson Cancer Center (Houston, TX) (73 admissions) for gastrointestinal complications. Neutropenia and/or fever accounted for 56 of these admissions. Fourteen patients (16 admissions) were diagnosed with colitis. All had abdominal pain at median Day 6 of their chemotherapy cycle (range, 3–8 days), with or without other symptoms. Computed tomography scans of the abdomen and pelvis were abnormal for the 10 patients tested, whereas only 3 of the 9 patients who underwent radiographic abdominal series had abnormal findings. Two patients had a colonoscopy that confirmed the diagnosis of colitis. Blood cultures were positive in only 3 (20%) of 15 colitis events. All eight patients tested for Clostridium difficile toxin were negative. One patient died of sepsis. An autopsy subsequently revealed cecal ulceration. Two patients had bowel perforations requiring hemicolectomy. Colitis recurred in two patients after they resumed taxane‐based chemotherapy without dose reduction. Dose reductions prevented the recurrence of colitis in seven patients. Treatment discontinuation of taxane‐based chemotherapy also prevented disease recurrence.CONCLUSIONSAcute abdominal pain in patients with breast carcinoma treated with taxane‐based chemotherapy signaled a potentially fatal colitis, and warrants aggressive supportive care. Dose reduction or discontinuation of taxane‐based chemotherapy may prevent the recurrence of colitis. Cancer 2004. © 2004 American Cancer Society.
Intensity‐modulated radiotherapy for early‐stage nasopharyngeal carcinoma
Authors: Kwong Dora L. W. , Pow Edmond H. N. , Sham Jonathan S. T. , McMillan Anne S. , Leung Lucullus H. T. , Leung W. Keung , Chua Daniel T. T. , Cheng Ashley C. K. , Wu Po M. , Au Gordon K. H. 
Published: August 2004

AbstractBACKGROUNDXerostomia is a uniform complication after radiotherapy (RT) for nasopharyngeal carcinoma (NPC). Dosimetric studies suggested that intensity‐modulated RT (IMRT) can spare part of the parotid glands from high‐dose radiation. Disease control and salivary function after IMRT for early‐stage NPC was studied prospectively.METHODSThirty‐three patients with T1,N0–N1,M0 NPC were treated with IMRT from 2000 to 2002. The prescribed dose was 68–70 grays (Gy) in 34 fractions to gross tumor volume, 64–68 Gy to the planning target volume, and 70 Gy to enlarged cervical lymph nodes. Nineteen patients had stimulated whole salivary (SWS) flow assessment and stimulated parotid salivary (SPS) flow assessment at baseline and at 2 months, 6 months, 12 months, 18 months, and 24 months after the completion of IMRT.RESULTSAt a median follow‐up of 2 years, only 1 neck failure was observed. The 2‐year and 3‐year local control, distant metastases‐free, and overall survival rates all were 100%. The lymph node control and progression‐free survival rates were 100% at 2 years and 92.3% at 3 years, respectively. The average mean dose to the parotid gland was 38.8 Gy. The SWS and SPS flow showed continuous recovery: 60% and 47.1% of patients recovered at least 25% of their baseline SPS flow and SWS flow, respectively, at 1 year after completion of IMRT, and the proportions rose to 85.7% and 71.4%, respectively, by 2 years. The pH and buffering capacity of saliva also improved with time.CONCLUSIONSParotid‐sparing IMRT achieved good locoregional control, and there was continuous recovery of salivary flow, pH, and buffering capacity in the first 2 years after IMRT in patients with NPC. Cancer 2004. © 2004 American Cancer Society.