bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of segment 32–47 of cholecystokinin receptor type A in CCK8 binding: synthesis, nuclear magnetic resonance, circular dichroism and fluorescence studies
Authors: De Luca Stefania , Ragone Raffaele , Bracco Chiara , Digilio Giuseppe , Tesauro Diego , Saviano Michele , Pedone Carlo , Morelli Giancarlo 
Published: March 2003

AbstractThe segment 32–47 of the N‐terminal extracellular domain of the type A cholecystokinin receptor, CCKA‐R(32–47), was synthesized and structurally characterized in a membrane mimicking environment by CD, NMR and molecular dynamics calculations. The region of CCKA‐R(32–47) encompassing residues 39–46 adopted a well‐defined secondary structure in the presence of DPC micelles, whereas the conformation of the N‐terminal region (segment 32–37) could not be uniquely defined by the NOE derived distance constraints because of local flexibility. The conformation of the binding domain of CCKA‐R(32–47) was different from that found for the intact N‐terminal receptor tail, CCKA‐R(1–47). To assess whether CCKA‐R(32–47) was still able to bind the nonsulfated cholecystokinin C‐terminal octapeptide, CCK8, a series of titrations was carried out in SDS and DPC micelles, and the binding interaction was followed by fluorescence spectroscopy. These titrations gave no evidence for complex formation, whereas a high binding affinity was found between CCKA‐R(1–47) and CCK8. The different affinities for the ligand shown by CCKA‐R(32–47) and CCKA‐R(1–47) were paralleled by different interaction modes between the receptor segments and the micelles. The interaction of CCKA‐R(32–47) with DPC micelles was much weaker than that of CCKA‐R(1–47), because the former receptor segment lacks proper stabilizing contacts with the micelle surface. In the case of SDS micelles CCKA‐R(32–47) was found to form non‐micellar adducts with the detergent that prevented the onset of a functionally significant interaction between the receptor segment and the micelle. It is concluded that tertiary structure interactions brought about by the 1–31 segment play a key role in the stabilization of the membrane bound, biologically active conformation of the N‐terminal extracellular tail of the CCKA receptor. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis and conformational investigation of cyclic dipeptides: 7‐membered rings containing α‐ and β‐amino acids
Authors: Müller‐Hartwieg J. Constanze D. , Akyel Kayhan G. , Zimmermann Jürg 
Published: March 2003

AbstractThe synthesis of heterocyclic compounds containing the 7‐membered ring system [1,4]diazepane‐2,5‐dione is described. The aim of this study was to elaborate the solid phase and solution synthesis of eight representatives of the cyclic scaffold and to investigate their chemical stability and their conformational properties. The solid phase synthesis was performed on aminomethyl polystyrene resin using 5‐(4‐formyl‐3,5‐dimethoxyphenoxy)valeric acid as a backbone linker system (BAL‐linker). After attachment of the α‐ and β‐amino acid and deprotection of the amino function, the dipeptide ester was obtained. The molecule was cyclized on the solid support by treatment with NaOMe in MeOH/NMP. The product was cleaved from the resin by TFA. For the solution pathway the linear dipeptides were synthesized by coupling of the BOC‐protected L‐α‐amino acid with the β2‐amino acid ester (EDC/HOBT). After N‐ and C‐terminal deprotection of the dipeptide, the linear species was cyclized with EDC/HOBT at a concentration of 3 mM in DMF. The products showed high chemical stability after storage in DMSO at room temperature for weeks. The x‐ray and two dimensional NMR investigations were performed to investigate the conformation of the molecules. Three types of configuration could be distinguished by NMR, depending on the substitution pattern of the cyclic compounds. The x‐ray results confirmed the NMR observations. In general the 7‐membered rings showed rigidity, thus they could represent optimal scaffolds for new receptor ligands. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Inhibition of ascorbic acid‐induced modifications in lens proteins by peptides
Authors: Argirova Mariana , Argirov Ognyan 
Published: March 2003

AbstractThe effects of three dipeptides L‐phenylalanyl‐glycine, glycyl‐L‐phenylalanine, and aspartame (L‐aspartyl‐L‐phenylalanine, methyl ester) as inhibitors of the ascorbic acid‐induced modifications in lens proteins were studied. Their efficiency was compared to that of two known inhibitors—aminoguanidine and carnosine. The tested dipeptides diminished protein carbonyl content by 32–58% and most moderated the formation of chromophores, as measured by the absorbency at 325 nm of the glycated proteins. The appearance of non‐tryptophan fluorescence (excitation 340 nm/emission 410 nm) was observed for proteins glycated with ascorbic acid. All of the dipeptides examined, as well as aminoguanidine, decreased this glycation‐related fluorescence. The potential inhibitors prevented the intensive formation of very high molecular weight aggregates. A competitive mechanism of their inhibitory effect was proposed, based on the reactivity of individual substances toward ascorbic acid. These findings indicate that they have a potential for use as alternatives for aminoguanidine as an anti‐glycation agent. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
On the Dispersion and Small‐Amplitude Oscillation Measurements of High Amylopectin Potato Starch
Authors: Ortega‐Ojeda Fernando E. , Larsson Helena , Eliasson Ann‐Charlotte 
Published: March 2003

AbstractDifferential scanning calorimetry (DSC), optical microscopy and turbidity measurements were used to define experimental conditions (time, temperature and shearing) for dissolving high amylopectin potato starch (HAPP) granules. A simple, less time consuming and non‐chemical method for preparing starch samples was established. Small‐amplitude oscillation measurements were used to characterise the behaviour of the resulting solutions. The DSC, microscopy and turbidity experiments showed that preparing the samples at 140 °C was necessary to dissolve HAPP, with no further detectable granule structures. Rheological measurements showed that the storage (G') and loss (G'') moduli increased with concentration. At a HAPP concentration of 2 % G'' > G' and the system behaved like a diluted solution. The frequency dependence also decreased with increasing concentration. At 14 % HAPP, the system showed more gel‐like properties with G' more or less independent of frequency.
Kinetics of Starch Gelatinisation and Mass Transfer During Cooking of Taro (Colocasia esculenta L. Schott) Slices
Authors: Njintang Yanou Nicolas , Mbofung Carl M. F. 
Published: March 2003

AbstractTaro slices of different thickness (5, 10 and 15 mm) were cooked for varying periods of time (5, 10, 20 and 40 min) and dried at different temperatures (70, 80 and 90 °C). Flours obtained from the slices were evaluated for their degree of gelatinisation, their content of sugars and phenolic compounds. The results showed that starch gelatinisation as well as the diffusion of sugars and phenolic compounds during cooking each followed a first‐order reaction of the general form ln(1‐α) = ‐k·t. The gelatinisation rate constant, kG , and the rate constants for the diffusion of sugars and phenolic compounds, kL, increased with temperature and decreased with slice thickness.
Parametric analysis of analytical solutions to one‐ and two‐dimensional problems in couple‐stress theory of elasticity
Authors: Kulesh M.A. , Matveenko V.P. , Shardakov I.N. 
Published: March 2003

AbstractIn this paper the fundamentals of the asymmetric elasticity theory are used to consider one‐ and two‐dimensional boundary‐value problems: shear deformation of elastic infinite plane layer(plate); torsion of a ring rigidly fixed at the external contour due to rotation of the inner one; deformation of a plane washer caused by a rigid displacement of the internal contour relative to the external one; the Kirsch problem on unilateral extension of a plate loosened by a circular hole. The solution of each problem is compared with the corresponding solution obtained in the framework of the classical theory of elasticity. The comparison is made in terms of macro‐parameters introduced to characterize the degree of difference between these solutions. The analysis of the obtained results show that for each problem under consideration this difference is not essential. It is worthy of note that the macro‐parameters used for comparison can be constructively measured by experiment. The obtained results can be used to outline a key diagram of experiments enabling one to detect the effects of “couple” response of the examined medium.
Comparison of Surgical Treatments of Gallstone Ileus: Preliminary Report
Authors: Doko Marko , Zovak Mario , Kopljar Mario , Glavan Elizabet , Ljubicic Neven , Hochstädter Hrvoje 
Published: March 2003

AbstractGallstone ileus is an uncommon cause of small bowel obstruction, accounting for only 1% to 4% of all intestinal obstructions. In the group of patients over 65 years of age, gallstones cause about 25% of all non‐strangulated obstructions of the small bowel. Gallstone ileus is burdened with high mortality rate, ranging from 12% to 18%, and most patients are of advanced age, with many other concomitant diseases that may increase the operative risk. The purpose of this study was to compare the two investigated surgical procedures: treatment of intestinal obstruction alone or combined with urgent cholecystectomy and fistula repair. Analysis of 30 patients undergoing operation for gallstone ileus at the Clinical Hospital “Sestre milosrdnice” between 1985 and 2001 is presented. Patients were treated either for ileus alone (group 1, 11 patients) or as one‐stage procedure with urgent fistula closure (group 2, 19 patients). Operating time was significantly longer for the one‐stage procedure. Complications occurred in 3 of 11 patients (27.3%) from group 1 and in 11 of 18 patients (61.1%) from group 2 (one tailed, p = 0.043). One patient in group 1 died and two patients in group 2 died. Urgent fistula repair was significantly associated with the occurrence of complications (odds ratio [OR] 12.1, 95% confidence internal [95% CI] 1.2–121.5). Simple enterotomy should be the procedure of choice for patients with gallstone ileus. The one‐stage procedure including urgent fistula repair should be reserved only for highly selected patients with absolute indications.
Mechanical factors influence the expression of endostatin—an inhibitor of angiogenesis—in tendons
Authors: Pufe Thomas , Petersen Wolf , Kurz Bodo , Tsokos Michael , Tillmann Bernhard , Mentlein Rolf 
Published: March 2003

AbstractAvascular zones of tendons are predisposed for degenerative changes and spontaneous rupture. Therefore, we analyzed the expression of the endogenous angiogenesis inhibiting factor endostatin in human fetal and adult tendons by immunohistochemical and biochemical methods. Moreover, to elucidate factors involved in the regulation of vascularity, we exposed primary cultures of rat tendon cells to intermittent hydrostatic pressure (0.2 MPa, 0.1 Hz for 24 h), and measured the endostatin content by ELISA and the effect of the conditioned medium to the proliferation of human umbilical vein endothelial cells (HUVEC).In fetal tendons high endostatin levels could be quantified by ELISA whereas low levels were found in adult tissue. In fetal tendons endostatin could also be immunostained in endothelial cells but mainly in fibroblasts. In adult Achilles tendons endostatin immunostaining was restricted to endothelial cells. In the tibialis posterior tendon—as an example for “wrap around”—endostatin immunostaining remained positive in the fibrocartilage adjacent to the medial malleolus. Fibrochondrocytes of the type II collagen positive fibrocartilage were intensively stained with the endostatin antibody. Factor VIII immunostaining showed that this region was largely avascular. Monolayer cultures of tendon cells released measurable amounts of endostatin into their culture supernatants. Application of intermittent hydrostatic pressure increased endostatin expression significantly. The conditioned media of tendon fibroblasts cultivated under intermittent hydrostatic pressure inhibited the proliferation of HUVEC in a dose dependent way.The spatial expression of endostatin in adult gliding tendons suggests that mechanical factors are involved in the regulation of this anti‐angiogenic factor. In accordance, tendon cells exposed to intermittent hydrostatic pressure inhibit endothelial cell proliferation via humoral factors and produce endostatin. These findings support the view that the development and maintenance of avascular zones in tendons might be caused by a mechanically induced upregulation of anti‐angiogenic factors. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Glucose‐mediated in vitro glycation modulates biomechanical integrity of the soft tissues but not hard tissues
Authors: Reddy G. Kesava 
Published: March 2003

AbstractGlycation induced crosslinking of connective tissue collagen is thought to be involved in the pathogenesis of various disorders associated with diabetes and aging. Although the formation of the glycation related collagen crosslinks appears to be universal for all tissues, currently it is unknown whether differences exist between soft and hard tissue biomechanics in response to glucose‐mediated in vitro glycation. In this study, the impact of non‐enzymatic glycation was investigated on tendons and bones, using them as models for soft and hard tissue respectively. Achilles tendons from rabbits, and femur and tibia from rats, were subjected to in vitro glycation with glucose. Sixty days following glycation, the matrix integrity of the tendons and bones was evaluated and compared with the respective non‐glycated tissue (n = 10 in each group). The results revealed that the impact of glycation was significant on the tendon but not on the bone. Measurements of the biomechanical stability of glycated tendons indicated a significant increase in maximum load (21%), Young's modulus of elasticity (72%), energy to yield (35%) and toughness (68%) compared to the non‐glycated tendons. No significant differences were found in breaking strength, bending stiffness, energy to yield and toughness between glycated and non‐glycated femurs or tibias. The deformation of both soft and hard tissue was unaffected by the glycation. Measurements at ultimate tissue failure (break point) revealed that glycated tendons bore significantly higher load and energy absorption than non‐glycated tendons. In contrast, the deformation of the glycated tendons at break point was considerably reduced as compared to control tendons. However, glycation had no significant effects on the hard tissue biomechanical properties at break point. The results of this study demonstrate that in vitro glycation influences the biomechanical properties of soft tissue but not hard tissue. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Long‐term intermittent shear deformation improves the quality of cartilaginous tissue formed in vitro
Authors: Waldman Stephen D. , Spiteri Caroline G. , Grynpas Marc D. , Pilliar Robert M. , Kandel Rita A. 
Published: March 2003

AbstractThe formation of cartilaginous tissue in vitro is a promising alternative to repair damaged articular cartilage. However, recent attempts to tissue‐engineer articular cartilage that has similar properties to the native tissue have proven to be difficult. The in vitro‐formed cartilaginous tissue typically has a similar proteoglycan content to native cartilage, but has a reduced collagen content and only a fraction of the mechanical properties. In this study, we investigated whether the intermittent application of cyclic shearing forces during tissue formation would improve the tissue quality. Chondrocyte cultures were stimulated at a 2% shear strain amplitude at a frequency of 1 Hz for 400 cycles every 2nd day. At one week, both collagen and proteoglycan synthesis increased (23 ± 6% and 20 ± 6%, respectively) over the unstimulated, static controls. At four weeks, an increased amount of tissue formed (stimulated: 1.85 ± 0.08, unstimulated: 1.58 ± 0.07 mg dry wt.). This tissue contained approximately 40% more collagen (stimulated: 511 ± 23, unstimulated: 367 ± 24 μg/construct) and 35% more proteoglycans (stimulated: 376 ± 21, unstimulated: 279 ± 26 μg/construct). Tissues that formed in the presence of shearing forces also displayed a 3‐fold increase in compressive load‐bearing capacity (stimulated: 16 ± 5, unstimulated: 5 ± 1 kPa max. equilibrium stress) and a 6‐fold increase in stiffness (stimulated: 112 ± 36, unstimulated: 20 ± 6 kPa max. equilibrium modulus) compared to the static controls. These results demonstrate that intermittent application of dynamic shearing forces over a four‐week period improves the quality of cartilaginous tissue formed in vitro. Interestingly, low amplitudes of shear stimulation for short periods of time (6 min of stimulation applied every 2nd day) produced these changes. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Spermine prevents cytochrome c release in glucocorticoid‐induced apoptosis in mouse thymocytes
Authors: Hegardt Cecilia , Andersson Gunnar , Oredsson Stina M 
Published: March 2003

AbstractApoptosis can be induced in primary cultures of mouse thymocytes using the glucocorticoid dexamethasone. Addition of the polyamine spermine simultaneously with dexamethasone reduces the induction of apoptosis compared to treatment with dexamethasone alone. We investigated the signal transduction pathway at the mitochondrial level in order to elucidate spermine's protective effect. Mitochondrial involvement is evident due to the loss of mitochondrial transmembrane potential, release of cytochrome c into the cytosol and activation of caspase‐9 in dexamethasone‐treated thymocytes. The addition of spermine inhibited the release of cytochrome c from the mitochondria into the cytosol, and also the activation of caspase‐9. When the mitogen concanavalin A (Con A) was added to dexamethasone‐ plus spermine‐treated thymocytes, the number of apoptotic cells in the pre‐G1peak was reduced compared to thymocytes treated with only dexamethasone plus spermine. Comparing concanavalin A added to dexamethasone‐treated or to dexamethasone plus spermine‐treated thymocytes, showed a markedly reduced pre‐G1peak in the latter. Thus, the spermine‐induced inhibition of cytochrome c release confers a survival advantage on thymocytes.
Anti‐oxidative properties of beta‐blockers and angiotensin‐converting enzyme inhibitors in congestive heart failure
Authors: Chin Bernard S.P. , Langford Nigel J. , Nuttall Sarah L. , Gibbs Christopher R. , Blann Andrew D. , Lip Gregory Y.H. 
Published: March 2003

AbstractBackground:Chronic elevation of plasma catecholamines and sympathetic stimulation in chronic heart failure (CHF) leads to increased production of free radicals, and so possibly to endothelial damage/dysfunction and atheroma formation. Abnormal oxidative stress may therefore be related to some of the high mortality and morbidity in CHF. The objective of the present prospective open study was to compare the effects of β‐blockers and ACE inhibitors in relation to oxidative stress and endothelial damage in CHF.Methods:We studied 66 outpatients with CHF: 46 patients were established on an ACE inhibitor and were then started on a β‐blocker, and 20 patients not previously on ACE‐inhibitors were started on lisinopril. Baseline levels of the measured parameters were compared to 22 healthy control subjects. Serum lipid hydroperoxides (LHP) and total antioxidant capacity (TAC) were determined as indices of oxidative damage and antioxidant defence, and plasma von Willebrand factor (vWf) as an index of endothelial damage/dysfunction.Results:Baseline indices for the measures of oxidative damage and endothelial function in the 66 CHF patients were significantly higher than healthy control subjects [median LHP 7.5 (5.9–12.6) vs. 4.8 μmol/l, P=0.0022; TAC 428 (365–567) vs. 336 Trollox Eq. Units, P=0.0005; mean vWf 134±27 vs. 89±23 IU/dl, P<0.0001]. Following 3 months of maintenance therapy with β‐blockers, there was significant reduction in LHP levels, but not TAC or vWf. ACE inhibitor therapy also significantly reduced vWf levels, but failed to have any statistically significant effects on LHP or TAC.Conclusion:This pilot study suggests that oxidative stress in CHF may be due to increased free radical production or inefficient free radical clearance by scavengers. β‐Blockers, but not ACE inhibitors, reduced lipid peroxidation in patients with CHF. No relation was demonstrated between a reduction in oxidative damage and endothelial damage/dysfunction.
Christian Love and Biological Altruism
Authors: Meisinger Hubert 
Published: March 2003

The first part of my investigation of the Christian love command and biological research on altruism is organized around three key themes whose different forms both in the theological and in the sociobiological context are investigated: The awareness of expanding inclusiveness concerns the issue of extending love or altruistic behavior beyond the most immediate neighbor, even to enemies. The awareness of excessive demand concerns the question of the ability of the human being, to fulfill an excessive demand placed by the command of love or by altruistic admonitions. Threshold awareness finally concerns the question whether love or altruism constitutes a step on the way to a “new human” and a “new world.”In the second part I introduce two models for the relationship between Christian religion or theology and sociobiology. The model by Ralph Wendell Burhoe is characterized by a functional approach toward religion, which is the crucial factor within culture for motivating human beings to act altruistically toward nonrelated individuals. This functional analysis of religion is a constructive contribution to a scientific description of the world. The other model, by Philip Hefner, is theologically oriented and emphasizes the intrinsic character of altruistic love, which has its origin in God and whose anthropological preconditions are elucidated in sociobiological research.The goal of this investigation is to show that a better mutual understanding is preferable to a total incorporation of the investigated domains into each other.
How Science Is a Resource and a Challenge for Religion: Perspective of a Theologian
Authors: Hefner Philip 
Published: March 2003

Religion is characterized by the attempt to create a worldview, which is in effect the effort of worldbuilding. By this I mean that religion aims to focus on all of the elements that make up a person's world or a community's world and put those elements together in a manner that actually constructs a total picture that gives meaning and coherence to life. In this activity of worldbuilding, science and religion meet each other at the deepest level. Science makes a fundamental contribution to this worldbuilding effort and also poses a challenge. There are good grounds for this twofold role of science: (1) scientific knowledge is basic to any worldview in our time, and (2) science and its related technology engender new and often confusing experiences that require inclusion in any worldbuilding.The challenge of science is that its contribution does not easily accommodate worldbuilding because of the factors of chance, indeterminacy, blind evolution, and heat death that are ascertained through scientific knowledge. Science is a resource for us in that the features of its knowledge can lend actuality and credibility to worldbuilding.Religion needs science for its worldbuilding if its interpretations are to be credible and possess vivid actuality. Science needs religion because, unless its knowledge is incorporated into meaningful worldbuilding, science forfeits its standing as a humanistic enterprise and instead may count as an antihuman methodology and body of knowledge.