bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties and biocompatibility of polypropylene graft copolymer films
Authors: El‐Rehim H. A. Abd , El‐Arnaouty M. B. 
Published: January 2004

AbstractModifying the surfaces of polymers has received a great deal of attention, because it could bring about specific surface characteristics such as antithrombogenic property. Therefore, N‐vinyl pyrrolidone/sodium acrylate (NVP/Na‐AAc) binary monomers were introduced onto polypropylene (PP) films by a radiation grafting method. The effect of solvent and comonomer composition on the degree of grafting was determined. Studies of the mechanical properties and water content of such graft copolymers showed that as the grafting yield increases the elongation percent decreases. However, the water content increases with increasing grafting yield. The blood compatibility of the original PP and PP‐g–NVP/Na‐AAc films was evaluated by determination of the extent of platelet adsorption and thrombus formation. The blood compatibility of PP‐g–NVP/Na‐AAc seems to be better than that of original PP. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 209–215, 2004
Electric‐current‐induced detachment of Staphylococcus epidermidis strains from surgical stainless steel
Authors: van der Borden A. J. , van der Mei H. C. , Busscher H. J. 
Published: January 2004

AbstractInfection of percutaneous biomaterials implants, such as fixation frames used for the repair of complicated fractures in orthopedics, is a major complication that almost inevitably leads to replacement of the implant. As antibiotic therapy usually has little impact on biomaterial‐associated infections, it is the aim of this article to examine whether implant‐associated Staphylococcus epidermidis and Staphylococcus aureus strains could be stimulated to detach from a surgical stainless steel anode during application of an electric current. First, bacteria were allowed to adhere from a flowing suspension of physiological ionic strength in a parallel plate flow chamber to a stainless‐steel surface, after which the suspension was replaced by a bacterium‐free solution with a specified ionic strength (0.5–150‐mM potassium phosphate). DC currents ranging from 15 to 125 μA were applied to induce bacterial detachment. Initial detachment decreased with increasing ionic strength at 100 μA. The percentage detachment achieved by application of an electric current after 2.5 h was highest (95%) in 1‐mM potassium phosphate and decreased to 15% when the ionic strength exceeded 40 mM. The electric current did not significantly affect the percentage detachment, but initial detachment rates increased with increasing current from 1000 cm−2 s−1 at 15 μA to 7000 cm−2 s−1 at 125 μA. Although different isolates of S. epidermidis and S. aureus showed different patterns of current‐induced detachment, all strains could be stimulated to detach. The results of this study define ionic‐strength conditions and electric currents yielding staphylococcal detachment from surgical stainless steel and therewith point to a pathway for the treatment and prevention of percutaneous metal‐implant infection. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 160–164, 2004
The effect of tranexamic acid in fibrin sealant on adhesion formation in the rat
Authors: Wiseman David , Lyachovetsky Yacov , Keidan Ilan , Trout J. Richard , Nur Israel 
Published: January 2004

AbstractThe objective of the research was to determine the effect of the type, dose, and volume of anti‐fibrinolytic agents (tranexamic acid, aprotinin) added to fibrin formulations, on adhesion development. Adhesions were induced in 228 male rats by creating apposing parietal and visceral peritoneal defects. Animals were randomized to receive no treatment or a fibrin formulation containing aprotinin or tranexamic acid. Seven days later the incidence of adhesions, and the force and energy required to detach them, were determined. Adhesions developed in 13/13 rats in the control and aprotinin groups. Treatment with fibrin (100 mg/ml tranexamic acid) resulted in adhesions in 4/14 rats (as strips, p ≤ 0.0005), 4/10 rats (as spray, p ≤ 0.0036), and 12/15 rats (by drip). The reduction of adhesions was dependent on the concentration of tranexamic acid with strip and spray application. Using commercial formulations, tranexamic‐acid–containing fibrin (10/15, p = 0.042), but not aprotinin‐containing fibrin (13/15), reduced the incidence of side‐wall adhesions from 15/15 in controls. Fibrin containing either tranexamic or aprotinin reduced the incidence and severity of adhesions. This effect was greater when tranexamic acid was used and was dependent on the mode of administration, the volume, and to a degree, the concentration of tranexamic acid. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 222–230, 2004
The development of theoretical relationships between some handling parameters (setting time and setting temperature), composition (relative amounts of initiator and activator) and ambient temperature for acrylic bone cement
Authors: Milner Richard 
Published: January 2004

AbstractCommercially available acrylic bone cements are two‐component systems based on the polymerization of methyl methacrylate around poly(methyl methacrylate) particles. When benzoyl peroxide (BPO), which is the initiator, in the powder component meets accelerator (N,N‐dimethyl‐p‐toluidine (DMpT)) in the liquid component, radicals are produced, initiating the polymerization. This solidifies the cement. In this work, kinetic expressions have been developed that describe the relationship between bone cement setting time on the one hand, and BPO and DMpT concentrations on the other. Changes in setting time with ambient temperature follow a complex relationship, because both the polymerization process (initiation, propagation, and termination) and the swelling and dissolution of the polymer particles contribute to setting. The contribution of polymer swelling and dissolution to the setting process was determined by developing a relationship between the doughing time, which is substantially independent of DMpT or BPO concentrations, and ambient temperature. A value of 64 kJ mol−1 was found for the activation energy for this process. An activation energy for the overall setting process of 68 kJ mol−1 was determined from setting‐time measurements over several ambient temperatures. This indicates that the sensitivity of setting time to temperature depends more on swelling and dissolution than on the polymerization process. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 180–185, 2004
Maternal and cord blood serum levels of zinc, copper, and iron in healthy pregnant Jordanian women
Authors: Awadallah S.M. , Abu‐Elteen K.H. , Elkarmi A.Z. , Qaraein S.H. , Salem N.M. , Mubarak M.S. 
Published: January 2004

AbstractAltered plasma levels of zinc, copper, and iron during pregnancy are known to have profound effects on pregnant women and their neonates. The status of these elements is not known in pregnant women in Jordan. During the three trimesters of pregnancy, blood specimens were collected from 186 healthy pregnant women aged 17–45 years and from cord blood of 92 of their neonates. The mean neonatal birth weight was 3.34 ± 0.44 kg. Maternal and cord blood serum levels of zinc, copper, and iron were determined by atomic absorption spectrophotometry, and hemoglobin concentration was determined by hematology cell counter. The results indicate significantly lower serum zinc levels and higher copper and iron levels in cord blood than in maternal blood. During the three trimesters of pregnancy, the serum levels of zinc and copper significantly decreased and increased, respectively, whereas the levels of serum iron were unchanged. Significant positive correlation was observed only between zinc levels of cord blood and birth weight. During third trimester, the mean serum levels of zinc and iron were significantly lower in anemic pregnant women (group I: Hb less than 11.0 g/dL, n = 36) than that in nonanemic pregnant women (group II: Hb > or = 11.0 g/dL, n = 56). There was no noticeable difference between group I and group II regarding cord blood parameters on one hand and neonatal birth weight on the other hand. Similar significant positive correlation was observed between serum zinc levels of cord blood and birth weight in both groups. These results indicate that Jordanian women during pregnancy follow a well‐balanced and adequate diet regime. J. Trace Elem. Exp. Med. 17:1–8, 2004. © 2004 Wiley‐Liss, Inc.
Possible role of trace elements in the hypoglycemic effect of plants extract in diabetic rats
Authors: Al‐Awadi F.M. , Anim J.T. , Srikumar T.S. , Al‐Rustom Mona 
Published: January 2004

AbstractThe present study is designed to investigate the possible role of zinc, copper, manganese, and selenium on the hypoglycemic action of a plants mixture and alfalfa using a diabetic rat model. Diabetes was induced in male Wister rats using streptozotocin and confirmed by estimation of glucose levels in blood and urine and further by histologic examination of the pancreas. The animals were treated with the plants mixture and alfalfa extracts orally by gastric intubation for 7 days. Untreated normal and diabetic rats were included as controls. After evaluating glucose tolerance, animals were sacrificed and organs harvested for trace element analysis and histopathological study. The concentration of zinc, copper, manganese, and selenium in plasma, liver, and pancreas of diabetic rats was significantly lower than those of nondiabetic controls. Treatment of diabetic rats with plants mixture and alfalfa significantly decreased the blood glucose concentration but increased the levels of zinc, copper, manganese, and selenium in plasma, liver, and pancreas. Similar changes occurred in the nondiabetic normal control animals treated with the same products. Histological and immunohistochemical examination also confirmed the presence of more β‐cells in the islets of treated diabetic animals compared with untreated diabetic controls. There was no histological evidence of damage to the liver of either diabetic or normal control animals treated with the plants extract. The present study indicated that treatment of diabetes with naturally available plants mixture appears to be effective and the hypoglycemic effect could be through a multimechanism action including that exerted by the trace element content in the different tissues including the pancreas. J. Trace Elem. Exp. Med. 17:31–44, 2004. © 2004 Wiley‐Liss, Inc.
Inhibitory effect of tannic acid on iron–dextran‐augmented and 7,12‐dimethyl benz(a)anthracene‐initiated skin carcinogenesis
Authors: Babaei Hossein , Nayebi Ali Reza Mohajjel , Rezazadeh Hassan , Abdulla Mohamed 
Published: January 2004

AbstractTannic acid (TA) is naturally occurring polyphenol present in fruits and vegetables. In this study we report that TA inhibits the carcinogenic effect of 7,12‐dimethylbenz(a)anthracene (DMBA) in normal and iron‐overloaded mice skin. Albino Swiss mice were given iron–dextran and pretreated with a single topical application of tannic acid; after 1 h, tumors were initiated by multiple topically application of DMBA. Appearance, number, and percent tumor incidence were recorded. When compared with the control group, the pretreated groups showed a significantly higher inhibition of tumor incidence. The induction of [3H]thymidine incorporation in cutaneous DNA and lipid peroxidation was inhibited in TA‐pertreated animals as compared with the normal control group. Based on this study, we propose that TA significantly inhibits the augmentation potential of iron–dextran. A depletion in lipid peroxidation levels in TA‐pretreated groups indicates that excessive generated oxidants in the mice skin tissues may be quenched by TA and because of the chelation of redox active iron and its faster elimination from the body. In conclusion, our data suggest that TA may be an effective chemopreventive agent and may offer protection against iron mediated skin cancer. J. Trace Elem. Exp. Med. 17:21–29, 2004. © 2004 Wiley‐Liss, Inc.
Lead intoxication: Histological and oxidative damage in rat cerebrum and cerebellum
Authors: Sidhu Pardeep , Nehru Bimla 
Published: January 2004

AbstractThe present experiment was designed to study the neurotoxic consequences of lead exposure on antioxidant enzymes like glutathione, glutathione peroxidase, super oxide dismustase, and catalase along with structural changes both in cerebrum as well as cerebellum. Lead was administrated orally in the doses of 50 mg/kg for a period of 8 weeks and study was performed at the end of exposure. Decrease in the concentration of all the antioxidant enzymes was observed, and after lead treatment, transverse sections of cerebrum showed degeneration of neurons. Disruption of normal arrangement of cell layers was seen. Cells were bigger in size with large vascular spaces around them. Lead treatment for 8 weeks also was enough to disrupt the normal arrangement of cellular layer of cerebellum. Large spaces in between purkinje cell layer and granular layer were seen. J. Trace Elem. Exp. Med. 17:45–53, 2004. © 2004 Wiley‐Liss, Inc.
Can long‐term exposure to chromium improve insulin sensitivity in chromium mine workers?
Authors: Tuzcu A. , Bahcecı M. , Dursun M. , Parmaksız Y. , Ertem M. , Dalgıc A. , Turgut C. , Kale E. 
Published: January 2004

AbstractThe purpose of this work was to evaluate insulin sensitivity in chromium mine workers exposed to chromium chronically. Body mass index, waist circumference, fat mass and percent, lipid levels, serum glucose, insulin, leptin and chromium levels, HOMA (%S), and HOMA (%B) values were measured in 93 male workers and 94 age‐ and body mass index‐matched healthy controls. Fat mass and fat percent of workers were higher than control subjects (P < 0.01 and P < 0.0001, respectively). Mean insulin level of the workers was lower than control subjects (6.2 ± 4.9 μU/mL and 9.38 ± 5, respectively, P < 0.0001). Mean serum leptin levels was also lower than the control group (8.47 ± 6.5 ng/mL and 19.0 ± 10.8, respectively, P < 0.0001). Serum chromium was higher than the control subjects (407.7 ± 224.2 nmol/L and 4.45 ± 3.9, respectively, P < 0.00001). Mean HOMA (%S) index of workers was higher than control subjects (114.4 ± 55.6 and 55.7 ± 40.6, P < 0.001). Serum high‐density lipoprotein cholesterol levels of the workers were significantly higher than the control group (P < 0.02). In conclusion, long‐term exposure to chromium may improve insulin sensitivity and β‐cell function. This improvement appears to be a result of low body fat mass and fat percent in body composition. In addition, chromium usage may have useful effects in the insulin sensitivity and therefore in development of type 2 diabetes mellitus. J. Trace Elem. Exp. Med. 17:55–63, 2004. © 2004 Wiley‐Liss, Inc.
Compound load of copper and iron in the livers of pretreatment patients with Wilson's disease
Authors: Harashima Ai , Hattori Ai , Hayashi Hisao , Wakusawa Shinya , Kusakabe Atsuhiko , Fujita Yoshikazu , Tanaka Minoru , Yano Motoyoshi , Yoshioka Kentaro 
Published: January 2004

AbstractCeruloplasmin is a major ferroxidase in sera, and people with hypoceruloplasminemia might have iron load complications. We used histochemical and X‐ray microanalysis techniques on pretreatment liver specimens from five patients with Wilson's disease. Serum levels of ceruloplasmin and ferritin were determined before chelation therapy. All the patients showed hypoceruloplasminemia ranging from 15 to 160 mg/L. Histo‐chemical copper was positively stained in four of the five patients. Copper deposits were clearly observed in the hepatocyte lysosomes of one patient. High serum ferritin levels ranging from 188 to 400 ng/mL were found. Histochemical iron was positive in the livers of two patients. Iron‐specific X‐rays were positive in the hepatocyte lysosomes of all the patients. These findings suggest that compound load of copper and iron is a fundamental finding in the liver of Wilson's disease with hypoceruloplasminemia. Copper cytotoxicity is a primary target for chelation therapy, and iron load, if hepatotoxic, should be treated by phlebotomy. J. Trace Elem. Exp. 17:65–73, 2004. © 2004 Wiley‐Liss, Inc.
Effect of melatonin treatment on liver and thymus zinc levels in young and middle‐aged rats
Authors: Öztürk Güler , Akbulut K. Gonca , Afrasyap Lale , Sevinç Deniz 
Published: January 2004

AbstractMelatonin (MEL) is the main neurohormone of the pineal gland. Zinc (Zn) is an essential trace element that is required as a catalytic component for more than 200 enzymes. Both MEL and Zn are considered beneficial for anti‐immunosenescence. Recent findings have shown that MEL can modulate Zn turnover. The aim of this study was to investigate the effect of MEL treatment on the tissue Zn levels in young (4 months) and middle‐aged (14 months) rats. Male wistar rats received during 3 weeks subcutaneous injection of MEL (10 mg/kg). After 3 weeks, rats were decapitated and tissue samples were collected. Zn levels were measured by spectrophotometric assay. In conclusion, MEL decreased liver Zn levels both in young and middle‐aged rats. In addition, Zn levels in young control group were significantly higher than middle‐aged control group. However, MEL treatment increased thymus Zn levels in middle‐aged group compared with the control. These findings indicate that tissue Zn levels are significantly affected by MEL treatment. J. Trace Elem. Exp. Med. 17:75–80, 2004. © 2004 Wiley‐Liss, Inc.
Structure determination of aligned samples of membrane proteins by NMR spectroscopy
Authors: Nevzorov Alexander A. , Mesleh Michael F. , Opella Stanley J. 
Published: January 2004

AbstractThe paper briefly reviews the process of determining the structures of membrane proteins by NMR spectroscopy of aligned samples, describes the integration of recent developments in the interpretation of spectra of aligned proteins and illustrates the application of these methods to the trans‐membrane helical domain of a protein. The emerging methods of interpreting the spectral parameters from aligned samples of isotopically labeled proteins provide opportunities for simultaneously assigning the spectra and determining the structures of the proteins, and also for comparing the results from solid‐state NMR experiments on completely aligned samples with those of solution NMR experiments on weakly aligned samples. Copyright © 2004 John Wiley & Sons, Ltd.
Structural studies of apoptosis and ion transport regulatory proteins in membranes
Authors: Franzin Carla M. , Choi Jungyuen , Zhai Dayong , Reed John C. , Marassi Francesca M. 
Published: January 2004

AbstractSolid‐state NMR spectroscopy is being used to determine the structures of membrane proteins involved in the regulation of apoptosis and ion transport. The Bcl‐2 family includes pro‐ and anti‐apoptotic proteins that play a major regulatory role in mitochondrion‐dependent apoptosis or programmed cell death. The NMR data obtained for 15N‐labeled anti‐apoptotic Bcl‐xL in lipid bilayers are consistent with membrane association through insertion of the two central hydrophobic α‐helices that are also required for channel formation and cytoprotective activity. The FXYD family proteins regulate ion flux across membranes, through interaction with the Na+, K+‐ATPase, in tissues that perform fluid and solute transport or that are electrically excitable. We have expressed and purified three FXYD family members, Mat8 (mammary tumor protein), CHIF (channel‐inducing factor) and PLM (phospholemman), for structure determination by NMR in lipids. The solid‐state NMR spectra of Bcl‐2 and FXYD proteins, in uniaxially oriented lipid bilayers, give the first view of their membrane‐associated architectures. Copyright © 2004 John Wiley & Sons, Ltd.
Structural diversity of amyloid fibril formed in human calcitonin as revealed by site‐directed 13C solid‐state NMR spectroscopy
Authors: Naito Akira , Kamihira Miya , Inoue Ryozo , Saitô Hazime 
Published: January 2004

AbstractFibril formation in human calcitonin (hCT) from aqueous solution at pH 4.1 was examined and compared with those at pH 3.3 and 7.5 corresponding to three different net charges by means of site‐directed 13C solid‐state NMR spectroscopy. Notably, the observed 13C chemical shifts and lineshapes of the 13C CP/MAS spectra differed substantially among fibrils prepared at different pHs. It was found that antiparallel β‐sheet structures were formed at pH 7.5 and 4.1 in the central core regions. In the C‐terminal region, random coils were formed at both pH 7.5 and 4.1, although the random coil region at pH 4.1 was larger than that at pH 7.5. Fibrillation kinetics analyzed by a two‐step autocatalytic reaction mechanism showed that the rate constants k1 and k2 for nucleation and maturation reactions of the fibril formation, respectively, were separately determined and the values correlated well with the net positive charges of Lys18 and His20 rather than the existence of a negative charge of Asp15. Further, an attempt was made to assess interatomic distances between amide nitrogen and carbonyl carbon of neighboring chains of 13C, 15N‐labeled hCT and a model pentapeptide by 13C REDOR measurements by taking into account its dipolar interaction analyzed by the 3 spin system proposed previously. A unique chain packing of the antiparallel β‐sheets was proposed as a dominant fibril structure, although the possibility of a contribution of chain packing consisting of sliding one or two residues perpendicular to the fibril direction cannot be ruled out. In addition, it appears that the phenyl rings of Phe16 are aligned on the same side of the β‐sheet and make the β‐sheet stable by forming π–π interactions between the β‐strands. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation of the dynamics of an elastin‐mimetic polypeptide using solid‐state NMR
Authors: Yao Xiao L. , Conticello Vincent P. , Hong Mei 
Published: January 2004

AbstractElastin is the main structural protein that provides elasticity to various tissues and organs in vertebrates. Molecular motions are believed to play a significant role in its elasticity. We have used solid‐state NMR spectroscopy to characterize the dynamics of an elastin‐mimetic protein as a function of hydration to better understand the origin of elastin elasticity. Poly(Lys‐25), [(VPGVG)4(VPGKG)]39, has a repeat sequence common to natural elastin. 13C cross‐polarization and direct polarization spectra at various hydration levels indicate that water enhances the protein motion in a non‐uniform manner. Below 20% hydration, the backbone motion increases only slightly whereas above 30% hydration, both the backbone and the side‐chains undergo large‐amplitude motions. The motional amplitudes are extracted from 13C–1H and 1H–1H dipolar couplings using 2D isotropic–anisotropic correlation experiments. The root mean square fluctuation angles are found to be 11–18° in the dry protein and 16–21° in the 20% hydrated protein. Dramatically, the amplitudes increase to near isotropic at 30% hydration. Field‐dependent 1H rotating‐frame spin–lattice relaxation times (T1ρ) indicate that significant motions occur on the microsecond time‐scale (1.2–2.3 µs). The large‐amplitude and low‐frequency motion of poly(Lys‐25) at relatively mild hydration indicates that the conformational entropy of the protein in the relaxed state contributes significantly to the elasticity. Copyright © 2004 John Wiley & Sons, Ltd.