bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant lipases: Biocatalyst aqueous environment in relation to optimal catalytic activity in lipase‐catalyzed synthesis reactions
Authors: Caro Yanis , Pina Michel , Turon Fabrice , Guilbert Stephane , Mougeot Estelle , Fetsch David V. , Attwool Philip , Graille Jean 
Published: August 2002

AbstractAdsorption and desorption isotherms of two commercial enzyme preparations of papain and bromelain were determined with a Dynamic Vapor System. The Guggenheim‐Anderson‐deBoer (GAB) modeling of the obtained sorption isotherms allowed the definition of different levels of hydration of those samples. Afterward, these enzyme preparations were used as biocatalysts in water and solvent‐free esterification and alcoholysis reactions. The evolution of the obtained fatty acid ester level as a function of the initial hydration level of the biocatalyst, i.e., thermodynamic water activity (aw) and water content, was studied. The results show an important correlation between the initial hydration level of the biocatalyst and its catalytic activity during the lipase‐catalyzed synthesis reactions. Thus, the Carica papaya lipase (crude papain preparation) catalytic activity is highly dependent on the biocatalyst hydration state. The optimized synthesis reaction yield is obtained when the aw value of the enzyme preparation is stabilized at 0.22, which corresponds to 2% water content. This optimal level of hydration occurs on the linear part of the biocatalyst's sorption isotherm, where the water molecules can form a mono‐ or multiple layer with the protein network. The synthesis reaction yield decreases when the aw of the preparation is higher than 0.22, because the excess water molecules modify the system equilibrium leading to the reverse and competitive reaction, i.e., hydrolysis. These results show also that an optimal storage condition for the highly hydrophilic crude papain preparation is a relative humidity strictly lower than 70% to avoid an irreversible structural transition leading to a useless biocatalyst. Concerning the bromelain preparation, no effect of the hydration level on the catalytic activity during esterification reactions was observed. This biocatalyst has too weak a catalytic activity which makes it difficult to observe any differences. Furthermore, the bromelain preparation is far more hydrophobic as it adsorbs only 18 g of water per 100 g of dry material at aw around 0.90. No deliquescence of this enzymatic preparation is oserved at this aw value. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 693–703, 2002; DOI 10.1002/bit.10155
Estimation of hyphal tensile strength in production‐scale Aspergillus oryzae fungal fermentations
Authors: Li Zheng Jian , Shukla Vivek , Wenger Kevin , Fordyce Andrew , Pedersen Annemarie Gade , Marten Mark 
Published: August 2002

AbstractFragmentation of filamentous fungal hyphae depends on two phenomena: hydrodynamic stresses, which lead to hyphal breakage, and hyphal tensile strength, which resists breakage. The goal of this study was to use turbulent hydrodynamic theory to develop a correlation that allows experimental data of morphology and hydrodynamics to be used to estimate relative (pseudo) tensile strength (σpseudo) of filamentous fungi. Fed‐batch fermentations were conducted with a recombinant strain of Aspergillus oryzae in 80 m3 fermentors, and measurements were made of both morphological (equivalent hyphal length, L) and hydrodynamic variables (specific power input, $\bar \varepsilon$; kinematic viscosity, v). We found that v increased over 100‐fold during these fermentations and, hence, Kolmogorov microscale (λ) also changed significantly with time. In the impeller discharge zone, where hyphal fragmentation is thought to actually take place, λ was calculated to be 700–3500 μm, which is large compared to the size of typical fungal hyphae (100–300 μm). This result implies that eddies in the viscous subrange are responsible for fragmentation. Applying turbulent theory for this subrange, it was possible to calculate σpseudo from morphological and hydrodynamic measurements. Pseudo tensile strength was not constant but increased to a maximum during the first half and then decreased during the second half of each fermentation, presumably due to differences in physiological state. When a literature correlation for hyphal fragmentation rate (kfrag) was modified by adding a term to account for viscosity and tensile strength, the result was better qualitative agreement with morphological data. Taken together, these results imply hyphal tensile strength can change significantly over the course of large‐scale, fed‐batch fungal fermentations and that existing fragmentation and morphology models may be improved if they accounted for variations in hyphal tensile strength with time. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 601–613, 2002; DOI 10.1002/bit.10209
Modeling of the enzymatic kinetic synthesis of cephalexin—Influence of substrate concentration and temperature
Authors: Schroën C. G. P. H. , Nierstrasz V. A. , Moody H. M. , Hoogschagen M. J. , Kroon P. J. , Bosma R. , Beeftink H. H. , Janssen A. E. M. , Tramper J. 
Published: August 2002

AbstractDuring enzymatic kinetic synthesis of cephalexin, an activated phenylglycine derivative (phenylglycine amide or phenylglycine methyl ester) is coupled to the nucleus 7‐aminodeacetoxycephalosporanic acid (7‐ADCA). Simultaneously, hydrolysis of phenylglycine amide and hydrolysis of cephalexin take place. This results in a temporary high‐product concentration that is subsequently consumed by the enzyme. To optimize productivity, it is necessary to develop models that predict the course of the reaction. Such models are known from literature but these are only applicable for a limited range of experimental conditions.In this article a model is presented that is valid for a wide range of substrate concentrations (0–490 mM for phenylglycine amide and 0–300 mM for 7‐ADCA) and temperatures (273–298 K). The model was built in a systematic way with parameters that were, for an important part, calculated from independent experiments. With the constants used in the model not only the synthesis reaction but also phenylglycine amide hydrolysis and cephalexin hydrolysis could be described accurately. In contrast to the models described in literature, only a limited number (five) of constants was required to describe the reaction at a certain temperature. For the temperature dependency of the constants, the Årrhenius equation was applied, with the constants at 293 K as references. Again, independent experiments were used, which resulted in a model with high statistic reliability for the entire temperature range. Low temperatures were found beneficial for the process because more cephalexin and less phenylglycine is formed.The model was used to optimize the reaction conditions using criteria such as the yield on 7‐ADCA or on activated phenylglycine. Depending on the weight of the criteria, either a high initial phenylglycine amide concentration (yield on 7‐ADCA) or a high initial 7‐ADCA concentration (yield on phenylglycine amide) is beneficial. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 171–178, 2001.
Wet extrusion of fibronectin–fibrinogen cables for application in tissue engineering
Authors: Underwood S. , Afoke A. , Brown R. A. , MacLeod A. J. , Shamlou P. Ayazi , Dunnill P. 
Published: August 2002

AbstractA method for the wet extrusion of human plasma‐derived fibronectin–fibrinogen cables is described. Solutions of fibronectin and fibrinogen with and without sodium alginate and carboxymethylcellulose (CMC) are tested. The rheological properties of the protein solutions changed from Newtonian to shear thinning non‐Newtonian in the presence of small quantities of these additives, the apparent viscosity increased, and the extrusion properties of the protein solutions improved. Cables were prepared using a capillary with a diameter of 1 mm and overall length of 18 mm. Cable diameter was reduced to about 0.5 mm by drawing using a series of rollers. Cables prepared with sodium alginate were found to have suitable properties, and those made with CMC were sticky and difficult to handle. Solutions containing no sodium alginate required a minimum total protein concentration of about 70 mg/mL for extrusion. Extruded cables were prepared with solutions containing 140 mg/mL total protein with 12.9 mg/mL alginate (high protein), and 46 mg/mL total protein with 47.6 mg/mL of sodium alginate (high alginate). The mechanical strength of the extruded cables was within the range suitable for application in tissue engineering. Extrusion of the protein solutions into cables was achieved in a coagulation bath. Cables with a mechanical strength of approximately 30 N/mm2, suitable for wound repair and nerve regeneration applications, were prepared with a coagulation bath containing 0.25 M HCl, 2% CaCl2 at a pH of <0.9. These cables also had a large average elongation at break of 52%, and showed an increase in cable length after breakage (permanent set) of 20%, demonstrating the potential for drawing the cables down to a fine diameter. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 295–305, 2001.
Substrate controlled development of anaerobic acidifying aggregates at different shear rates in a gas lift reactor
Authors: Verschuren Peter G. , van den Heuvel Johannes C. 
Published: August 2002

AbstractThe influence of liquid shear rates on the development of acidifying mixed‐culture aggregates was studied in a gas‐lift reactor. The glucose concentration was kept at a constant and relatively high level by operating the reactor in pH‐auxostat mode. Size, strength, and wet density of aggregates cultivated at different superficial gas velocities (Ug) were investigated. Image analysis showed that the Sauter mean diameter (Ds) decreased with increasing Ug. A stirred tank was used to characterize the surface detachment rate (Rd) under non‐growth conditions. An exponential decrease was observed in Rd with the applied Ug during cultivation, i.e., aggregates became stronger. The increased strength coincided with an increase in aggregate wet density. Size classified aggregates showed an increase in Rd with the square of the aggregate diameter (Dp), however, this contribution was much smaller than the effect of adaptation. Experiments in a similar gas‐lift reactor under dynamic conditions without adaptation, showed that Rd increased exponentially with increasing Ug. So, two important contributions to Rd can be distinguished: adaptation, which induces stronger aggregates, and aggregate size, which makes them less susceptible to hydrodynamic shear. A general expression for Rd was derived, which depends on Dp and Ug. Combining this equation with the surface biomass growth rate (Rg) allowed for the estimation of the maximal diameter (Dmax) aggregates can reach at any Ug, and it was found that the estimated and measured Dmax were in good agreement. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 306–315, 2002.
Separation of cephalosporins on thin silica gel layers impregnated with transition metal ions and by reversed‐phase TLC
Authors: Bhushan Ravi , Thiong'o G. Thuku 
Published: August 2002

AbstractCephalosporin antibiotics were separated on thin layer plates impregnated with transition metal ions, Mn2+, Fe2+, Co2+, Ni2+ and Cu2+, using different concentrations. Various solvent systems were developed for the study and were used for separation of these analytes. Impregnation was observed to have an effect on hRF values, removed tailing of analytes and improved the resolution. The results have been discussed for each metal ion and compared, and the best conditions of separation have been identified. Activation time of thin layer plates impregnated with 0.1% FeSO4 was found to affect both hRF values and resolution of cephalosporins. New solvent systems are reported for both normal phase and reversed‐phase TLC. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of captopril in biological samples by high‐performance liquid chromatography with ThioGlo™3 derivatization
Authors: Aykin Nukhet , Neal Rachel , Yusof Mozow , Ercal Nuran 
Published: August 2002

AbstractCaptopril, a well‐known angiotensin converting enzyme (ACE) inhibitor, is widely used for treatment of arterial hypertension. Recent studies suggest that it may also act as a scavenger of free radicals because of its thiol group. Therefore, the present study describes a rapid, sensitive and relatively simple method for the detection of captopril in biological tissues with reverse‐phase HPLC. Captopril was first derivatized with ThioGlo™3 [3H‐Naphto[2,1‐b]pyran,9‐acetoxy‐2‐(4‐(2,5‐dihydro‐2,5‐dioxo‐1H‐pyrrol‐1‐yl)phenyl‐3‐oxo‐)]. It was then detected by fluorescence‐HPLC using an Astec C18 column as the stationary phase and a water:acetonitrile:acetic acid:phosphoric acid mixture (50:50; 1 mL/L acids) as the mobile phase (excitation wavelength, 365 nm; emission wavelength, 445 nm). The calibration curve for captopril was linear over a range of 10–2500 nM and the coefficient of variation acquired for the within‐ and between‐run precision for captopril was 0.5 and 3.8%, respectively. The detection limit of captopril with this method was found to be 200 fmol/20 µL injection volume. Its relative recovery from biological samples was determined to the range from 93.3 to 105.3%. Based on these results, we believe that our method is advantageous for captopril determination. Copyright © 2001 John Wiley & Sons, Ltd.
Abbreviations used:

ACE

angiotensin converting enzyme

PBPB

P‐bromophenylbromide

ROS

reactive oxygen species
Influence of oxidation and crosslinking on oxygen binding properties of mouse erythrocytes
Authors: Lotero L. A. , Jordán J. A. , López R. M. , García‐Pérez A. I. , Diez J. C. 
Published: August 2002

AbstractDifferent chemical treatments for mouse erythrocyte modification has been used. Oxidation treatments with Ascorbate/Fe3+, a system able to react with intracellular proteins, produced a displacement of the O2 binding equilibrium curve to a higher affinity behaviour with loss of the haemoglobin cooperativity for oxygen binding. Incubation of mouse erythrocytes with diamide showed that at low reagent concentration (0.8 mM) no modification on oxygen binding equilibrium curves was observed. At higher reagent concentration (2.0 mM), an increased affinity and a disappearance of the cooperative behaviour can be observed. Additionally, crosslinking reactions on mouse erythrocytes with band 3 crosslinkers seemed to affect oxygen binding properties when used at a crosslinker concentration of 5 mM. Oxyhaemoglobin levels in crosslinked and diamide‐treated erythrocytes are similar to those found in control cells. In contrast, ascorbate/Fe3+ treatments produced an increment in the proportion of methaemoglobin, decreasing the oxyhaemoglobin levels in these oxidized erythrocytes. Copyright © 2001 John Wiley & Sons, Ltd.
Postoperative coronary revascularization on LVAD support for surgically inaccessible myocardial ischemia
Authors: Kollar Andras , Misra Vijay , Pierson Richard N. 
Published: August 2002

AbstractThe authors have used the concept of hybrid revascularization to salvage a patient in persistent cardiogenic shock after incomplete emergent surgical revascularization. While the patient was on left ventricular assist device support, a complex angioplasty was done on a surgically inaccessible right coronary artery, with subsequent cardiac recovery. Cathet Cardiovasc Intervent 2002;55:381–384. © 2002 Wiley‐Liss, Inc.
Claeys MJ, Bosmans JM, Hendrix J, Vrints CJ. Reliability of fractional flow reserve measurements in patients with associated microvascular dysfunction: Importance of flow on translesional pressure gradient. Cathet Cardiovasc Intervent 2001;54:427–434
Authors: Claey MJ , Bosmans JM , Hendrix J , Vrints CJ 
Published: August 2002

AbstractThe original article to which this Erratum refers was published in Catheterization and Cardiovascular Interventions; 2002; 54(4) 427–434
Transcatheter recanalization of the left main pulmonary artery after four years of complete occlusion
Authors: Fink Christoph , Peuster Matthias , Bertram Harald , Hausdorf Gerd 
Published: August 2002

AbstractA technique for transcatheter “reconstruction” of a completely occluded left pulmonary artery using radiofrequency perforation with subsequent balloon dilation and stent implantation is reported in a 7‐year‐old child. It is shown that transcatheter radiofrequency perforation can still be effective years after the occlusion of a vessel. Cathet Cardiovasc Intervent 2001;53:81–84. © 2001 Wiley‐Liss, Inc.
Standalone cutting balloon angioplasty for the treatment of stent‐related restenosis: Acute results and 3‐ to 6‐month angiographic recurrent restenosis rates
Authors: Miyamoto Takamichi , Araki Takao , Hiroe Michiaki , Marumo Fumiaki , Niwa Akihiro , Yokoyama Koichi 
Published: August 2002

AbstractDespite excellent acute reperfusion results, 20%–30% of patients who undergo coronary stent implantation will develop angiographic restenosis and may require same additional treatments. Cutting Balloon angioplasty (CBA) causes less histological damage outside of the incised area than a regular balloon. However, regular plain old balloon angioplasty is sometimes required before CBA, as is adjunctive stenting and adjunctive angioplasty. These adjunctive strategies may negate the advantages of CBA. There is little data available on CBA as a standalone therapy for stent‐related restenosis (SRS). The aim of this study was to evaluate the acute and 3‐ to 6‐month angiographic recurrent restenosis rates following standalone CBA in a patient population treated for SRS and in whom optimal acute results were obtained. In this study, 40 patients with SRS (54 lesions) underwent standalone CBA with optimal acute results. For all lesions, coronary angiography was conducted before and after a standalone CBA procedure for SRS and systematically during 3–6 months to assess recurrent angiographic restenosis rates in the study population. In the study lesions, SRS was either diffuse disease (> 15 mm; 52%) or focal type (48%). Cutting Balloon diameter was 3.20 ± 0.44 mm and maximal inflation pressure 8.7 ± 1.2 atm. Ratio of Cutting Balloon diameter to restenotic stent diameter was 0.996 ± 0.487. Multiple inflations (6 ± 3 times) were performed. Number of used Cutting Balloon was 1.02 ± 0.14. Complications were as follows; one non–Q‐wave MI (1.9%); 0 death (0%), and 17 repeat target lesion revascularizations (TLRs; 32%). Follow‐up coronary angiography (CAG) was not attained for one patient. The angiographic recurrent restenosis rate was 34%, with a higher rate observed when the SRS was diffuse type, 50% vs. 16% for focal‐type SRS (P < 0.01). The recurrent restenosis rate for smaller vessels (vessel diameter ≤ 3.0 mm) was the same as for larger ones. At follow‐up CAG, diffuse‐type recurrent restenosis (56%) presented nearly as frequently as that presenting in the original SRS lesions (52%). But four diffuse‐type SRS (29%) changed into focal‐type recurrent stenosis. In this study, standalone CBA for SRS with optimal acute results was associated with an angiographic restenosis rate of 34%. Diffuse‐type disease had a higher recurrent restenosis rate. When CBA achieves acute optimal results, adjunctive stenting or adjunctive PTCA are not always necessary, particularly when the SRS is focal. As a result of CBA, some diffuse‐type SRS may change into focal‐type recurrent stenosis by the time of the next intervention. Cathet Cardiovasc Intervent 2001;54:301–308. © 2001 Wiley‐Liss, Inc.
Determination of the absolute configuration of a key tricyclic component of a novel vasopressin receptor antagonist by use of vibrational circular dichroism
Authors: Dyatkin Alexey B. , Freedman Teresa B. , Cao Xiaolin , Dukor Rina K. , Maryanoff Bruce E. , Maryanoff Cynthia A. , Matthews Jay M. , Shah Rekha D. , Nafie Laurence A. 
Published: August 2002

AbstractWe present the results of a study using vibrational circular dichroism (VCD) for (+)‐1, which furnished an unambiguous determination of its absolute configuration as S. The most abundant conformation of (+)‐1 in CDCl3 solution was also established. Chirality 14:215–219, 2002. © 2002 Wiley‐Liss, Inc.
The challenge of completely ethical CI and the CHIP model
Authors: Charters Darren 
Published: August 2002

AbstractThis article examines difficulties that are present for competitive intelligence practitioners endeavoring to conduct ethical CI. It explores the basic schools of ethical thought and combines them to create a model for evaluating the ethics of potential competitive intelligence activities. It concludes by suggesting that using rigorous ethical evaluation in assessing CI activities does not have to sacrifice the competitive position of an organization. © 2001 John Wiley & Sons, Inc.
Contraction‐mediated pinocytosis of RGD‐peptide by dermal fibroblasts: Inhibition of matrix attachment blocks contraction and disrupts microfilament organisation
Authors: Sethi K. K. , Mudera V. , Sutterlin R. , Baschong W. , Brown R. A. 
Published: August 2002

AbstractForce generation in collagen and matrix contraction are basic functions of fibroblasts and important elements of tissue repair. Cell‐matrix attachment is critical to this contraction, involving RGD‐binding integrins. We have investigated how this process operates, in terms of force generation (in the Culture Force Monitor) and cytoskeletal structure, using a synthetic RGD‐decapeptide. The RGD‐peptide blocked force generation over the first 6 h, followed by near complete recovery by 20 h. However, dose response was complex indicating multiple processes were operating. Analysis of cytoskeletal structure after treatment with RGD‐peptide indicated major disruption with condensed aggregates of actin and microtubular fragmentation. Fluorescent labeling and tracking of the RGD‐peptide demonstrated intracellular uptake into discrete cytoplasmic aggregates. Critically, these RGD‐peptide pools co‐localised with the condensed actin microfilament aggregates. It is concluded that RGD‐peptide uptake was by a form of contraction‐mediated pinocytosis, resulting from mechanical tension applied to the untethered RGD‐peptide‐integrin, as contractile microfilament were assembled. These findings emphasize the importance of sound mechanical attachment of ligand‐occupied integrins (e.g., to extracellular matrix) for normal cytoskeletal function. Conversely, this aspect of unrestrained cytoskeletal contraction may have important pathogenic and therapeutic applications. Cell Motil. Cytoskeleton 52:231–241, 2002. © 2002 Wiley‐Liss, Inc.