bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization and Activation of Glucagon-Like Peptide-2 Receptors on Vagal Afferents in the Rat
Authors: Nelson David W. , Sharp James W. , Brownfield Mark S. , Raybould Helen E. , Ney Denise M.
Published: January 2007

Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent proglucagon-derived hormone that stimulates intestinal growth through poorly understood paracrine and/or neural pathways. The relationship between GLP-2 action and a vagal pathway is unclear. Our aims were to determine whether 1) the GLP-2 receptor (GLP-2R) is expressed on vagal afferents by localizing it to the nodose ganglia; 2) exogenous GLP-2 stimulates the vagal afferent pathway by determining immunoreactivity for c-fos protein in the nucleus of the solitary tract (NTS); and 3) functional ablation of vagal afferents attenuates GLP-2-mediated intestinal growth in rats maintained with total parenteral nutrition (TPN). A polyclonal antibody against the N terminus of the rat GLP-2R was raised and characterized. The GLP-2R was localized to vagal afferents in the nodose ganglia and confirmed in enteroendocrine cells, enteric neurons, and nerve fibers in the myenteric plexus using immunohistochemistry. Activation of the vagal afferent pathway, as indicated by c-fos protein immunoreactivity in the NTS, was determined by immunohistochemistry after ip injection of 200 μg human GLP-2. GLP-2 induced a significant 5-fold increase in the number of c-fos protein immunoreactive neurons in the NTS compared with saline. Ablation of vagal afferent function by perivagal application of capsaicin, a specific afferent neurotoxin, abolished c-fos protein immunoreactivity, suggesting that activation of the NTS due to GLP-2 is dependent on vagal afferents. Exogenous GLP-2 prevented TPN-induced mucosal atrophy, but ablation of vagal afferent function with capsaicin did not attenuate this effect. This suggests that vagal-independent pathways are responsible for GLP-2 action in the absence of luminal nutrients during TPN, possibly involving enteric neurons or endocrine cells. This study shows for the first time that the GLP-2R is expressed by vagal afferents, and ip GLP-2 activates the vagal afferent pathway.
Generation of Transgenic Rats Expressing Green Fluorescent Protein in S-100β-Producing Pituitary Folliculo-Stellate Cells and Brain Astrocytes
Authors: Itakura Eisuke , Odaira Kousuke , Yokoyama Kotaro , Osuna Marumi , Hara Takahiko , Inoue Kinji
Published: January 2007

Folliculo-stellate (FS) cells are known to act as sustentacular cells or scavenger cells in the anterior lobe. However, the precise function and origin of FS cells are still under discussion. Like brain astrocytes, FS cells contain S-100β protein, and FS cells can be detected immunocytochemically using antibodies for S-100β protein after fixation; however, living FS cells can not be detected. The generation of transgenic rats expressing green fluorescent protein (GFP) under the control of S-100β protein gene promoter may allow the detection of living FS cells, which may be an excellent tool for the study of FS cells. With the aim of generation of transgenic rats, we analyzed the promoter activity of the S-100β gene and found that intron 1 is important for cell-specific expression of the S-100β gene. Therefore, we obtained a DNA construct containing GFP gene under a part of the S-100 promoter with intron 1. We transfected the construct into rat embryos and succeeded in generating transgenic rats. The transgenic rats expressed GFP in FS cells specifically in the anterior lobe. GFP is also expressed in other known S-100β-expressing cells, i.e. brain astrocytes, adipocytes, and chondrocytes. We believe that the newly generated transgenic rats will provide a new approach for the study of FS cells and other S-100β protein-producing cells.
Cell-Free mRNA Concentrations of Plasminogen Activator Inhibitor-1 and Tissue-Type Plasminogen Activator Are Increased in the Plasma of Pregnant Women with Preeclampsia
Authors: Purwosunu Yuditiya , Sekizawa Akihiko , Koide Keiko , Farina Antonio , Wibowo Noroyono , Wiknjosastro Gulardi Hanifa , Okazaki Shiho , Chiba Hiroshi , Okai Takashi
Published: January 2007

Background: Detection of placental mRNA in maternal plasma has been reported in high-risk pregnancies. We attempted to investigate the concentrations of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (tPA) mRNA in maternal plasma in preeclampsia.

Methods: Peripheral blood samples were obtained from healthy pregnant women before and after delivery and also from women with or without preeclampsia. Plasma was isolated from these samples, and RNA was extracted. Plasma PAI-1 and tPA mRNA concentrations were then measured by use of reverse transcription PCR assays. The concentrations were converted into multiples of the median (MoM) of the controls adjusted for gestational age. Data were stratified and analyzed according to the clinical severity of preeclampsia and quantitative distribution of blood pressure and proteinuria.

Results: The median (minimum–maximum) PAI-1 mRNA MoM values for women with preeclampsia and controls were 2.48 (0.82–8.53) and 1.00 (0.41–2.33), respectively, whereas the median (minimum–maximum) tPA mRNA MoM values were 3.33 (1.01–10.58) and 1.00 (0.95–1.20), respectively. The concentrations of both PAI-1 and tPA mRNA were significantly increased in cases of preeclampsia, compared with controls (P <0.0001). The MoM values of both mRNA species were directly correlated with the severity of preeclampsia and were greatest among a subgroup of hemolysis, increased liver enzymes, and low platelets pregnancies.

Conclusion: Maternal plasma PAI-1 and tPA mRNAs are significantly increased in patients with preeclampsia and are positively correlated with the severity of preeclampsia.
Assymetric information in the financial market: Sequential move games
Authors: Trifunovic Dejan
Published: January 2007

This paper analyses equilibrium in financial market when investors are aymmetrically informed, by using the methodology of game theory. We will show that bid-ask spread is increasing in probability of insider trading. Dynamic trading models suggest that insider?s informational advantage over market-maker is diminishing in time. By using sequential trading models we can explain various types of market manipulations and stock market crashes.
Understanding the supply chain
Authors: Acimovic Slobodan
Published: January 2007

Supply chain management represents new business philosophy and includes strategically positioned and much wider scope of activity in comparison with its "older brother" - management of logistics. Philosophy of the concept of supply chain is directed to more coordination of key business functions of every link in distribution chain in the process of organization of the flow of both goods and information, while logistic managing instruments are focused on internal optimum of flows of goods and information within one company. Applying the concept of integrated supply chain among several companies makes the importance of operative logistics activity even greater on the level of one company, thus advancing processes of optimum and coordination within and between different companies and confirms the importance of logistics performances for the company?s profitability. Besides the fact that the borders between companies are being deleted, this concept of supply chain in one distribution channel influences increasing of importance of functional, i.e. traditional business managing approaches but instead it points out the importance of process managing approaches. Although the author is aware that "there is nothing harder, more dangerous and with uncertain success, but to find a way for introducing some novelties (Machiavelli), it would be even his additional stimulation for trying to bring closer the concept and goals of supply chain implementation that are identified in key, relevant, modern, theoretical and consulting approaches in order to achieve better understanding of the subject and faster implementation of the concept of supply chain management by domestic companies.
Efficacy and safety of peginterferon alfa-2a and ribavirin in patients with chronic hepatitis C virus infection
Authors: Delic Dragan
Published: January 2007

Introduction. Chronic hepatitis C remains a formidable threat to world health. Progression of chronic hepatitis C is associated with significant morbidity: cirrhosis, hepatic failure and hepatocellular carcinoma. The introduction of combined therapy with pegylated interferons and ribavirin has increased the sustained virologic response (SVR) in the much higher percentage than with previous treatment options, while the level of adverse effects has not changed significantely. The aim of this study was to assess the efficacy and safety of combined therapy (peginterferon alfa-2a + ribavirin) in Serbian population. Material and methods. Patients with genotypes 1 and 4 received a 48-week course of therapy of peginterferon alfa-2a (180 mg/week) and ribavirin (1000-1200 mg/day). Patients with genotypes 2 and 3 received the same doses of both drugs, but during 24 weeks. All patients were scheduled for follow-up visit 24 weeks after the end of treatment. Physicians were instructed to adjust the dose of both drugs if adverse events occurred. Standard PCR tests were used for qualitative and quantitative detection of viral RNA, as well as for determination of patients' genotypes. Results and discussion. A total of 95 patients were enrolled in the sutdy. The majority of patients were male (65.26%), aged 40 or under (52.63%), with genotype 1 (63.15%). The average duration of infection was 2.81+4.89 years, but still, the majority of patients (51.58%) had HCV infection for less than 2 years. Fibrosis was present in 69.47 % of patients, and cirrhosis in 21.06%. The most common mode of infection was through i.v. drug use (29.48%), but it was unknown in 32.63% of patients. The mean ALT value was 100.44+70.26, with the total of 93.68% of patients having elevated ALT level. At the end of treatment (EoT) time point, data were collected from 66 patients (69.47%), while at the end of follow-up (EoFU), data were collected from 68 patients (71.58%). This unusual drop-out rate of 28.42% was mainly caused by losing contact with patients (14.74%) and premature termination of therapy (13.68%). The primary parameter of efficacy SVR at the EoFU was achieved in 59 out of 68 patients (86.76%), while the secondary efficacy parameter (SVR at the EoT) was achieved in 77.27% of patients. Multiple regression analysis has established the initial level of ALT, patient's age and fibrosis level as main parameters statistically significantly impacting the outcome of treatment. Although without statistical significance, the trend of better outcomes was associated with early therapy (within 2 years from infection), and while the disease has not progressed (patients with fibrosis achieved SVR at the EoFU in 89.19% vs. 75.00% in patients with cirrhosis). The safety record was good, the most common adverse effects including cytopenia, rash and local reactions at the site of administration. Conclusion. Combination therapy with peginterferon alfa-2a and ribavirin is safe and well tolerated, with SVR achieved in 86.76% of patients. .
Effects of alendronate on bone mass in women with osteoporosis
Authors: Pilipovic Nada , Brankovic Slobodan , Vujasinovic-Stupar Nada
Published: January 2007

This paper presents the results of a two-year study of the effects of alendronate (Fosamax?) on bone mass in 187 women with osteoporosis, mean age 57.68 years. Bone mass, i.e. bone mineral density (BMD) was measured at the lumbar spine. Measurements were performed prior to treatment, one year and two years after treatment using the DEXA method. The BMD was examined in 65 women, mean age 54.02, taking calcium and vitamin D, and in 75 women mean age 57.16, without any therapy. The baseline BMD (T score) in the alendronate group was -2.87 SD, whereas in the two control groups it measured -1.86 SD and -2.02 SD, respectively. A significant improvement of bone mass, by 5.8%, was registered after a year of treatment with alendronate, and by 8.3% after two years. In patients receiving calcium and vitamin D, a significant increase of bone mass was established as well: by 2.9% after a year, but the values declined back to the baseline after the second year. In patients without any treatment the bone mass decreased by 0.6% after a year, and by 0.9% after the second year. .
Effects of new nitric oxide synthase inhibitors on spontaneous locomotor activity
Authors: Dzoljic Eleonora , Nesic Zorica , Stojanovic Radan , Vuckovic Sonja , Todorovic Zoran , Prostran Milica
Published: January 2007

Introduction. New nitric oxide synthase (NOS) inhibitors: 3-bromo-7-nitro- indazole (3-Br-7-NI), 1-(2-trifluoromethylphenyl) imidazole (TRIM), S-methyl-L-thiocitrulline (S-Me-TC) and 7-nitroindazole (7-NI) reduce spontaneous locomotor activity in mice. Material and methods. In order to elucidate central effects of NOS inhibitors on locomotor activity, the influence of 7-NI on electroencephalographic (EEG) power spectrum in rats was investigated. Results. 7-NI reduced the EEG power density in all frequency bands in rats, suggesting a depression of the central neuronal activity. The electrophysiologic power was most reduced in the range of 7-9 Hz of the rhythmic slow activity (theta rhythm), which is in accordance with decreased locomotor activity observed following administration of NOS inhibitors. Conclusion. The present results indicate that nitric oxide exerts an excitatory effect on central neuronal structures involved in regulation of locomotion. .
Epistaxis in patients with hereditary hemorrhagic teleangiectasia
Authors: Jovancevic Ljiljana , Mitrovic Slobodan
Published: January 2007

Introduction. Spontaneous recurrent epistaxis is the most common clinical manifestation of hereditary hemorrhagic teleangiectasia (HHT). It occurs in more than 90% of HHT patients and is the most distressing symptom. Nasal teleangiectasias tend to increase with age both in size and number, so epistaxis is heavier and more frequent. For patients with mild to moderate disease, there are many adequate treatment options. For those with severe disease, most treatments offer just a hemorrhage-free interval. Experienced otorhinolaryngologists who treat epistaxis in these patients often use the adage "to do as little as possible for as long as possible". Management of acute epistaxis. The recommendations for the management of acute epistaxis include: compression, use of topical antifibrinolytics, laser therapy, argon plasma coagulation therapy, fibrin sealant spray or gelatin sponge soaked in adrenaline. In cases of heavy acute epistaxis, an epistaxis balloon combined with artery ligation and/or embolization is the most effective treatment. Nasal packing and electrocauterisation should be avoided to prevent further trauma to the blood vessels. Treatment of recurrent epistaxis. Management of recurrent epistaxis includes topical application of laser energy (argon, Nd: YAG, KTP/532 and diode, not CO2), argon plasma coagulation in combination with 0.1% estriol ointment, caustics, antifibrinolytics, bleomycin and sclerosing substances. Systemic estrogen-progesterone at doses used for oral contraception may eliminate bleeding in women with heavy epistaxis. Systemic antifibrinolitics (used with extreme precaution) and septal dermoplasty give good results. The only method which successfully and permanently solves the problem of severe refractory epistaxis in hereditary hemorrhagic teleangiectasia is closure of the nasal cavities. .
Neurosurgical treatment of pain
Authors: Slavik Eugen
Published: January 2007

Introduction. Surgical treatment of chronic pain includes destructive procedures (neurectomy, rhizotomy, sympathectomy), often referred to as ablative, and accompanied by high morbidity and mortality rates. Surgical treatment of pain. During the past three decades, thanks to current knowledge on chronic pain mechanisms and technological developments, such as improved microsurgical and stereotactic techniques, guided by computerized tomography, magnetic resonance imaging and neural tissue impedance monitoring, the majority of ablative procedures have been replaced by new methods. Among them, a few can be considered as selectively and minimally ablative (microsurgical spinothalamic cordotomy, dorsal root entry zone lesions, limited midline myelotomy) and others as neuroaugumentative procedures for neuromodulatory processes (deep brain structures and spinal cord stimulation, drug-delivery systems). Neurosurgical procedures. Cordotomy is very effective in pain treatment and it may produce complete abolishment of pain, especially in patients suffering from neoplastic invasion of the brachial plexus (Pancoast?s syndrome) or lumbosacral plexus. Dorsal root entry zone operation is generally the only treatment option for pain due to root avulsion and segmental pain in spinal cord injury. Spinal cord stimulation is useful in management of pain following peripheral nerve injury. Deep brain stimulation is a promising treatment of central pain. Conclusion. The purpose of this review is to draw attention to neurosurgical approaches to treatment of chronic and opioid-resistant pain. .
Learning curve in performing radiofrequency ablation of accessory pathways in patients with Wolf-Parkinson-White syndrome
Authors: Vukajlovic Dejan , Neskovic Aleksandar
Published: January 2007

Introduction. This study examines the effect of operator experience on radiofrequency ablation (RFA) of accessory pathways success rate in patients with Wolff-Parkinson-White (WPW) syndrome. Material and methods. The first 100 consecutive patients with WPW syndrome treated by radiofrequency ablation at our Clinic, were divided into group A (first 50 patients) and group B (the following 50 patients). Various parameters were compared between these 2 groups. Results. The success rate in group A was 69% and in group B 92%, p<0,01. There were 6 patients with recurrent WPW syndrome, after 3 months of follow-up, 5 were from group A and 1 from group B, p<0,05. Significantly more applications of radiofrequency energy were delivered in group A (10,0?4,8 in group A and 6,2 ?3,1 in group B, p<0,05). Two patients from group A presented with complications: one had intermittent complete AV-block, and the other pericardial effusion. Conclusion. This study shows a clear learning curve in performing RFA of accessory pathways in patients with WPW syndrome. .
The use of low molecular weight heparins in patients with acute ST-elevated myocardial infarction
Authors: Petrovic Milovan , Panic Gordana , Canji Tibor , Srdanovic Ilija , Ivanovic Vladimir , Benc Dragan
Published: January 2007

Introduction. According to the published guidelines for the management of acute coronary syndromes (ACS), treatment of acute ST-elevated myocardial infarction is based on rapid revascularization, either mechanical or pharmacological. Pharmacological revascularization consists of fibrinolytic therapy with antiplatelet and anticoagulant therapy. In regard to the anticoagulant therapy, low molecular weight heparins (LMWHs) are of special importance. LMWHs cause less complications (bleeding, thrombocytopenia, better bioviability) in comparison with unfractionated heparin (UFH). Some studies on use of LMWHs in ACS, show that LMWHs are equally efficient and safe as UFH, causing less complications (different types of hemorrhagic complications) (ESSENCE, TIMI 11B (enoxaparin), FRAXIS - fraxiparin), whereas some studies show better efficacy and safety of enoxaparin in therapy of acute ST-elevated myocardial infarction (ASSENT 3, ASSENT 3 PLUS, HART II, AMI-SK). Material and methods. Inclusion criteria: acute anterior myocardial infarction with ST-elevation, first myocardial infarction, no other structural heart defects, no signs of cardiogenic shock. Our study included 30 patients receiving fibrinolytic therapy with streptokinase, antiplatelet therapy and LMWH during 6 days, and 30 patients receiving UFH instead of LMWH. The follow-up period lasted for 6 months. Results. Significantly more patients receiving unfractionated heparin presented with major adverse cardiac events (73.3%) in regard to patients in the study group (44,2% nadroparin, 39.8% enoxaparin) (p=0.025). In the group receiving UFH, 6.7% patients had hemorrhagic complications, while none of patients receiving LMWHs. An equal number of patients died. Conclusion. Patients who were treated with LMWHs experienced less major adverse cardiac events and lower mortality. None suffered from hemorrhagic complications. .
The broad line region of AGN: Kinematics and physics
Authors: Popovic L.C.
Published: January 2007

In this paper a discussion of kinematics and physics of the Broad Line Region (BLR) is given. The possible physical conditions in the BLR and problems in determination of the physical parameters (electron temperature and density) are considered. Moreover, one analyses the geometry of the BLR and the probability that (at least) a fraction of the radiation in the Broad Emission Lines (BELs) originates from a relativistic accretion disk.
Why there are no elliptical galaxies more flattened than E7: Thirty years later
Authors: Caimmi R.
Published: January 2007

Elliptical galaxies are modeled as homeoidally striated Jacobi ellipsoids (Caimmi and Marmo 2005) where the peculiar velocity distribution is anisotropic, or equivalently as their adjoint configurations i.e. classical Jacobi ellipsoids of equal mass and axes, in real or imaginary rotation (Caimmi 2006). Reasons for the coincidence of bifurcation points from axisymmetric to triaxial configurations in both the sequences (Caimmi 2006) contrary to earlier findings (Wiegandt 1982a,b, Caimmi and Marmo 2005) are presented and discussed. The effect of centrifugal support at the ends of the major equatorial axis is briefly outlined. The existence of a lower limit to the attening of elliptical galaxies is investigated in dealing with a number of limiting situations. More specifically, (I) elliptical galaxies are considered as isolated systems, and an allowed region within Ellipsoidland (Hunter and de Zeeuw 1997), related to the occurrence of bifurcation points from ellipsoidal to pear-shaped configurations, is shown to be consistent with observations; (II) elliptical galaxies are considered as embedded within dark matter haloes and, under reasonable assumptions, it is shown that tidal effects from hosting haloes have little inuence on the above mentioned results; (III) dark matter haloes and embedded elliptical galaxies, idealized as a single homeoidally striated Jacobi ellipsoid, are considered in connection with the cosmological transition from expansion to relaxation, by generalizing an earlier model (Thuan and Gott 1975), and the existence of a lower limit to the attening of relaxed (oblate-like) configurations, is established. On the other hand, no lower limit is found to the elongation of relaxed (prolate-like) configurations, and the existence of some sort of instability is predicted, owing to the observed lack of elliptical galaxies more attened or elongated than E7.
The expectation maximization algorithm as a powerful tool to solve the stellar membership in open clusters: An application to M67
Authors: Uribe A. , Barrera R. , Brieva E.
Published: January 2007

The EM algorithm is a powerful tool to solve the membership problem in open clusters when a mixture density model overlaping two heteroscedastic bivariate normal components is built to fit the cloud of relative proper motions of the stars in a region of the sky where a cluster is supposed to be. A membership study of 1866 stars located in the region of the very old open cluster M67 is carried out via the Expectation Maximization algorithm using the McLachlan, Peel, Basford and Adams EMMIX software.
On the convective cores of MS rotating stars
Authors: Kuzmanovska O.
Published: January 2007

An analysis of the influence of the uniform stellar rotation on masses and radii of convective cores of zero age stars is presented. The study also shows the dependence of the relative mass of the convective core on the parameters in the center (temperature, pressure) and on the surface (effective temperature, luminosity) of the star.
Corrections of proper motions in declination by using ILS data
Authors: Damljanovic G. , Pejovic N.
Published: January 2007

There are nowadays numerous astrometric ground{based observations of some stars referred to Hipparcos Catalogue, made at many observatories during the last century. We used the data on latitude variations, covering the period 1899.7 - 1979.0, of visual Zenith Telescopes (ZT) of International Latitude Service (ILS), to improve the Hipparcos proper motions in declination for stars observed at seven ILS stations: Carloforte, Cincinnati, Gaithersburg Kitab, Mizusawa, Tschardjui and Ukiah. About 15 years elapsed since the HIPPARCOS ESA mission (ESA 1997) observations (1991.25 is the epoch of this catalogue), and with the errors of the Hipparcos proper motions close to 1 mas/yr, the error of apparent places of stars is now more than 15 mas; so that it exceeds the error of the Hipparcos positions by one order of magnitude (which is about 1 mas). Also, for some Hipparcos stars, the errors of proper motions are much larger than the averaged value itself, even not realistic at all (Vondr?k et al. 1998); the Hipparcos astronomical satellite mission lasted less than four years, not enough to get a sufficient accuracy of the proper motions. To improve the accuracy of the proper motions for some Hipparcos stars, the ground-based data were used and some new catalogues were published (such as ARIHIP, EOC-2, etc) during the last decade. Our investigations are in accordance with the Earth Orientation Catalogue - EOC (Vondr?k and Ron 2003) one, based on the Earth rotation programmes ground{based data, but we used different method here. Our results yield better proper motions in declination for stars common to ILS and HIPPARCOS and a good agreement with those from EOC-2.
DepAstroCCD an original astrometric tool
Authors: Stojanovic I. , Segan S. , Glisovic P. , Pavlovic R.
Published: January 2007

A complex software for preparation and treatment of astro photographic plates and double-star observations recorded with CCD cameras is developed. The preparation interface contains a catalogue base for the choice of observation objects and an interface for bringing into accordance the telescope and CCD camera performance with the assumptions of the postprocessor interface. The processing is based on the original development of image gradient removing software and classical FFT method and autocorrelation. The software has been tested on several theoretical and real images of double stars.
Changes in the biochemical composition of saliva in diabetic patients
Authors: Andjelski-Radicevic Biljana , Mirkovic Silvija , Todorovic Tatjana , Zelic Obrad
Published: January 2007

Introduction: Diabetic patients, beside numerous acute and chronic complications, often have oral manifestations of the disease. Aim: The aim of the study was to establish changes in saliva of diabetic patients in relation to healthy population in order to use saliva in the disease monitoring, as well as the changes depending on the type of diabetes. Materials and methods: The study comprised 52 adult patients of both sexes and at the age between 18 and 79 with Diabetes mellitus type 1 and 2 who were treated at the Institute for endocrinology, diabetes and metabolic disorders of the Clinical center of Serbia. The control group consisted of 67 volunteers from Belgrade, students at the School of Dentistry, aged between 19 and 24. The whole of unstimulated and stimulated saliva was collected and biochemical parameters (glucose, total proteins, albumin, sodium and potassium) were determined by methods commonly used for serum. Results: The results showed that salivary potassium level was increased in saliva of diabetic patients, that of sodium and total proteins was decreased, and glucose and albumin did not show changes compared to the control group. Concentrations of total proteins and potassium were higher in patients with DM type 2, and sodium was higher in DM type 1 (p = 0.05). Conclusion: Diabetic patients often have changes in biochemical composition of saliva.
New gold dental alloy for metal-ceramic restorations
Authors: Rudolf Rebeka , Kramberger Janez , Zupancic-Hartner Tjasa , Maric-Dragas Aleksandra , Lazic Vojkan
Published: January 2007

Introduction: Porcelain to metal fused alloys with Au content are most frequently used in dentistry. Their characteristic is high biocompatibility and well fusion to ceramics. Aim of the study: The aim of this study was to present the procedure of production and technology of developing the new dental alloy with high gold content (Au). Materials and Methods: The dental alloy was melted and cast in a vacuum-induction melting furnace. Casting was followed by subsequent thermo-mechanical treatments (the procedures of profile and polish milling, and thermal treatment) and the cutting strips into regular shapes. Testing of the new Au dental alloy included an examination of alloy?s final condition. The measurement of hardness was carried out according to standard 6507-1:1998, and static tensile testing was performed for determination of the mechanical properties. Microscopic analysis of the dental alloy and the finished metal-ceramic bridge included an observation of the polished surface, and by performing qualitative and quantitative micro-chemical analyses. Results: The mechanical properties and hardness of new dental gold alloy was: Rp0.=630 [N/mm2], Rm =710 [N/mm2], A= 9%, 170 HV and CTE (25-600?C) about 14,55?10-6K-1. Macro-inspection of the finished metalceramic bridge showed that there was no porosity. However, during scanning electron microscopic examination, one of the tested sample shows porosity in one alloy region and in the ceramic layer. Detailed examination of the ceramic layer?s surface showed that there were two types of air or gas bubbles - larger with distinct bubbles (type I) and smaller with clearly porous microstructure (type II). Conclusions: According to the results of this study, it can be concluded that this new dental alloy from Zlatarna Celje satisfied all the required standards regarding mechanical properties and hardness. The application of new dental alloy with high gold content depends on the adequate technology when firing ceramics. It is necessary to obtain accurate oxidation temperature and cooling rates of metal-ceramic restorations because, otherwise, different defects may appear.
Properties of sintered Al2O3-Cr composites depending on the method of preparation of the powder mixture
Authors: Chmielewski M. , Pietrzak K. , Włosiński W.
Published: January 2007

Continuous progress in modern science and industry depends on the availability of new effective devices and materials. New generation materials should be characterized by a specified combination of properties which sometimes exclude one another. Al2O3-Cr composites belong to this group of materials. This study is concerned with the effect of the method of preparation of the starting powders upon the properties of sintered Al2O3-Cr composites. The composites were produced using powder mixtures with various volumetric shares of the starting powders (from 25 to 75vol.%). The mixtures were prepared by conventional mechanical mixing in a ball-mill or by mechanical alloying in a high-energy mill of the attritor type. It has been found that with mechanically alloyed powders the Al2O3-Cr composites have better bending strength, hardness and frictional wear resistance.
The effect of secondary abnormal grain growth on the dielectric properties of La/Mn co-doped BaTiO3 ceramics
Authors: Zivkovic Lj.M. , Paunovic V.V. , Stamenkov N.Lj. , Miljkovic M.M.
Published: January 2007

La/Mn-codoped BaTiO3 systems, obtained by solid state reactions, were investigated regarding their microstructure characteristics and ferroelectric properties. Different concentrations of La2O3 were used for doping, ranging from 0.1 to 5.0 at% La, while a content of Mn was constant at 0.05 at%. For all samples sintered below the eutectic temperature (1332?C), a uniform microstructure was formed with average grain size from 1-3 ?m. The appearance of secondary abnormal grains with (111) double twins grains with curved or faceted grain boundaries were observed in La/Mn BaTiO3 ceramics after sintering at temperatures above the eutectic temperature. All sintered samples exhibited a high electrical resistivity. Better dielectric performances were obtained for low doped samples (0.1 at% La) sintered at 1350?C. For samples with La content above 1.0 at% a lower value in dielectric permittivity at higher sintering temperature is due to secondary abnormal grain growth, and to the presence of a non-ferroelectric phase rich in La. The Curie constant together with other dielectric parameters were also calculated.
Sintering kinetics of MgCO3-TiO2 systems
Authors: Petrovic V.
Published: January 2007

Ceramic materials have been in use in many different areas of human well-being for a very long time. The most common way of obtaining this material is using the process of sintering. During mechanical activation inorganic materials are ground when the grain size reduced. The crystal structure distorts and also changes, leading some systems to a chemical reaction and formation of a new compound. In this work we explain the influence of mechanical activation on sintering kinetics in MgCO3-TiO2 systems. We noticed a temperature drop and time reduction needed for MgTiO3 sintering when the duration of mechanical activation was longer.
Respiratory impairment in Brazilian foundry workers exposed to sand
Authors: Mendonça E.M.C. , Silva R.C.C. , Bussacos M.A. , Algranti E.
Published: January 2007

Objective

Foundries date back to the 16th century in Brazil and still constitute a strong economic activity today. Workers are at risk of respiratory diseases due to various exposures such as polycyclic aromatic hydrocarbons, pyrolysis degradation products, mineral dust, organic dust, resin, and isocyanates. We evaluate respiratory morbidity among workers in foundries using sand.

Methods

Six foundries with sand molding operations were selected. Length of exposure in years was utilized as a surrogate for exposure. The medical evaluation consisted of a respiratory symptoms questionnaire, occupational history, spirometry, and chest X‐rays. Additionally, workers exposed to resins and a control group underwent bronchial provocation tests.

Results

A sample of 598 male workers with a mean age of 36.5 years (SD = 10.0) was analyzed. The mean length of exposure was 10.1 years (SD = 7.4). The overall prevalence of pneumoconiosis was 4.5%. Chronic bronchitis (CB) and X‐ray profusion were significantly related to the quartiles of length of exposure (trend tests: P = 0.0055 and P < 0.001, respectively). There was a significant risk of having an abnormal FVC and FEV1 with the presence of pneumoconiosis (OR = 4.63 CI 1.40‐13‐23, OR 3.34 CI 1.03–9.26, respectively). Workers exposed to resins compared with controls showed no differences in relation to spirometry, respiratory symptoms and bronchial reactivity.

Conclusions

There were significant associations between length of exposure CB and prevalence of profusion 1/0 or above. There was also a significant association for pneumoconiosis versus and abnormal FVC and FEV1. Foundry workers currently exposed to resins did not show an excess of respiratory symptoms, abnormal spirometry or increased bronchial reactivity. Am. J. Ind. Med. 50:83–91, 2007. © 2006 Wiley‐Liss, Inc.
A multi‐faceted approach to risk assessment of laboratory animal allergens at two facilities
Authors: Korpi A. , Lappalainen S. , Kaliste E. , Kalliokoski P. , Reijula K. , Pasanen A.‐L.
Published: January 2007

Background

Risk assessment of exposure to allergens is difficult because the relationship between exposure, sensitization, and symptoms has not been fully established. Laboratory animal allergens (LAA) are an important occupational health risk factor; 10–32% of workers exposed to these allergens develop allergic diseases. This article introduces a versatile approach to assessing the risks posed by LAA at two laboratory animal facilities.

Methods

The risk assessment approach that was used at the laboratory animal facilities included questionnaires for management and employees, a hazard identification visit and measurements in the workplaces, as well as the creation of a list of generally recommended procedures to reduce allergen exposure.

Results

The prevalence of work‐related allergic symptoms was 17%. Suggested countermeasures at the sites included changes in ventilation and work practices, reduction of unnecessary exposure, recommendations for more comprehensive use of personal protective equipment, and wider communication about LAA risks.

Conclusions

The approach managed to identify critical points and potential means for controlling LAA exposure. Am. J. Ind. Med. 50:127–135, 2007. © 2006 Wiley‐Liss, Inc.
Chemical depolymerization of dextran sulfate sodium—the application of size‐exclusion or ion‐pair liquid chromatography
Authors: Araki Yoshio , Sugihara Hiroyuki , Hattori Takanori
Published: January 2007

We reported previously a method for the separation and quantification of sulfated polysaccharides, dextran sulfate sodium (DSS), using fluorometric labeling and size‐exclusion chromatography (SEC). In the present study, we evaluated chemical depolymerization of DSS. In fluorometric analyses using SEC, pyridylamino‐DSS (PA‐DSS) was depolymerized under acidic conditions, but not under alkaline conditions. In addition, we used ion‐pair liquid chromatography (IPLC) and UV analyses for the separation and quantification of sulfate. Sulfate was considerably depleted from DSS under alkaline conditions, but little depleted under acidic conditions. Spectrophotometric studies using toluidine blue revealed that molecular mass is an important factor and a minimum molecular mass of 2500 is needed to induce metachromasia. Fluorometric analyses using SEC and UV analyses using IPLC allow for the detection of DSS, reactants and sulfate. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of plasma free 3‐nitrotyrosine and tyrosine by reversed‐phase liquid chromatography with 4‐fluoro‐7‐nitrobenzofurazan derivatization
Authors: Zhang Wei‐Zheng , Lang Charles , Kaye David M.
Published: January 2007

Oxidative stress plays an important role in pathogenesis of many diseases. Measurement of 3‐nitrotyrosine (NO2Tyr), as a potential biomarker for nitric oxide‐mediated damage, has recently been the focus of particular attention. We have developed an HPLC method with NBD‐F pre‐column derivatization followed by C18 cartridge cleaning. Using this method we achieved limits of detection of 0.5 and 1.1 nm for NO2Tyr and tyrosine (Tyr), respectively, close to that achieved by LS‐MS/MS. NO2Tyr and tyrosine concentrations were linear over the calibration ranges 0.5–100 nm and 1–320 µm, respectively, with correlation coefficients greater than 0.95. To evaluate the utility of this assay in plasma we analysed samples obtained from smokers and non‐smoking subjects. Consistent with the presence of elevated oxidative stress, the plasma NO2Tyr concentration and NO2Tyr:Tyr ratio of smokers were 17.42 ± 11.6 nm and 0.263 ± 0.192 nm/µm with 3.8 and 3.9 times higher (both p < 0.05), respectively, than that of non‐smoker controls (4.54 ± 2.75 nm and 0.067 ± 0.050 nm/µm, respectively). In conclusion, we have developed a novel HPLC assay for NO2Tyr without MS detection that is applicable to clinical studies addressing the pathophysiology and importance of oxidative stress. Copyright © 2007 John Wiley & Sons, Ltd.
Development and validation of a reversed‐phase HPLC method for determination of nitrendipine in rat plasma: application to pharmacokinetic studies
Authors: Venishetty Vinay Kumar , Durairaj Chandrasekar , Sistla Ramakrishna , Yamsani Madhusudhan Rao , Diwan Prakash V.
Published: January 2007

A simple and sensitive method for the determination of nitrendipine in rat plasma was developed using high‐performance liquid chromatography (HPLC). The procedure involves extraction of nitrendipine in dichloromethane/sodium hydroxide, followed by reversed phase HPLC using a Waters, Spherisorb ODS2 (250 × 4.6 mm, 5 µm) column and UV detection at 238 nm. The retention times of nitrendipine and internal standard (felodipine) were 5.0 min and 7.5 min, respectively. The calibration curves were linear over the range of 5 ng/mL (lower limit of quantification, LOQ) to 200 ng/mL for nitrendipine. The intra‐ and inter‐day coefficients of variation for all criteria of validation were less than 15% over the linearity range. The sensitivity and precision of the method were within the accepted limits (< 15%) throughout the validation period. The present method was also successfully applied for the study of plasma pharmacokinetics of nitrendipine loaded solid lipid nanoparticles (SLN) in rats. Copyright © 2007 John Wiley & Sons, Ltd.
Simultaneous determination of ZLR‐8 and its active metabolite diclofenac in dog plasma by high‐performance liquid chromatography
Authors: Jiao Haoyan , Xu Fengguo , Zhang Zunjian , Tian Yuan , Jiang Zhenzhou , Zhang Luyong
Published: January 2007

ZLR‐8 is a nitric oxide releasing derivative of diclofenac for the treatment of inflammation. In this paper, a sensitive and reliable high‐performance liquid chromatography method for simultaneous determination of ZLR‐8 and its active metabolite diclofenac in the plasma of beagle dogs has been developed and validated. After the addition of ketoprofen as the internal standard (IS), plasma samples were extracted with n‐hexane–isopropanol (95:5, v/v) mixture solution and separated by HPLC on a reversed‐phase C18 column with a mobile phase of gradient procedure. Analytes were determined by the UV detector which was set at 280 nm. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of ZLR‐8 and diclofenac were linear over the range 0.05–4.0 µg/mL. The within‐ and between‐batch precisions (RSD%) were lower than 10% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.05 µg/mL. The proposed method has been readily implemented in preclinical pharmacokinetics studies of ZLR‐8 and its active metabolite diclofeance. Representative plasma concentration vs time profiles resulting from administration of ZLR‐8 to beagle dogs are presented in this communication. Copyright © 2007 John Wiley & Sons, Ltd.
An automated method for peak detection and matching in large gas chromatography‐mass spectrometry data sets
Authors: Dixon Sarah J. , Brereton Richard G. , Soini Helena A. , Novotny Milos V. , Penn Dustin J.
Published: January 2007

A new approach for peak detection and matching has been developed and applied to two data sets. The first consisted of the Gas Chromatography‐Mass Spectrometry (GC‐MS) samples of 965 human sweat samples obtained from a population of 197 individuals. The second data set contained 500 synthetic chromatograms, and was generated to validate the peak detection and matching methods. The size of both of the data sets (around 500 000 detectable peaks over all chromatograms in data set 1, and around 100 000 in data set 2) would make it unfeasible to check manually whether peaks are matched. In the method described, the first procedure involves pre‐processing the data before carrying out the second procedure of peak detection. The final procedure of peak matching consists of three stages: (a) finding potential target peaks in the full data set over all chromatograms; (b) matching peaks in the chromatograms to these targets to form clusters of spectra associated with each target; (c) merging targets where appropriate. Peak detection and matching were applied to both data sets, and the importance of stage (c) of peak matching described. In addition to the analysis of the synthetic chromatograms, the method was also validated by shuffling the original order of the sweat chromatograms and performing the methods independently on the newly shuffled data. Copyright © 2007 John Wiley & Sons, Ltd.
Proton Walk in the Aqueous Platinum Complex [TpPtMeCO] via a Sticky σ‐Methane Ligand
Authors: Lo H. Christine , Iron Mark A. , Martin Jan M. L. , Keinan Ehud
Published: January 2007

Both experimental and theoretical evidence suggest that the proton exchange between water and the methyl group in [TpPt(CO)CH3] (1, Tp=hydridotripyrazolylborate) involves the formation and deprotonation of a “sticky” σ‐methane ligand. The efficiency of this nontrivial process has been attributed to the spatial orientation of functional groups that operate in concert to activate a water molecule and then achieve a multistep proton walk from water to an uncoordinated pyrazolyl nitrogen atom, to the methyl ligand, and then back to the nitrogen atom and water. The overall proton‐exchange process has been proposed to involve an initial attack of water at the CO ligand in 1 with concerted deprotonation by the uncoordinated pyrazolyl nitrogen atom. The pyrazolium proton is then transferred to the PtCH3 bond, leading to a σ‐methane intermediate. Subsequent rotation and deprotonation of the σ‐methane ligand, followed by reformation of 1 and water, result in scrambling of the methyl protons with the hydrogen atoms of water. An alternative two‐step process that involves oxidative addition and reductive elimination has also been considered. The two competing mechanistic routes from 1 into [D3]‐1, as well as the conversion of 1 into [TpPt(CH3)H2] (2), have been examined by density functional theory (DFT) using a variety of exchange‐correlation methods, primarily PW6B95, which was recently shown to be highly accurate for evaluating reactions of late‐transition‐metal complexes. The key role played by the free pyrazolyl nitrogen atom, acting as a proton carrier that abstracts a proton from water and transfers the proton to the PtCH3 bond, is reminiscent of the dual functionality of histidine in the catalytic triad of natural serine proteases.
Changes in cholesterol levels in the plasma membrane modulate cell signaling and regulate cell adhesion and migration on fibronectin
Authors: Ramprasad O. G. , Srinivas G. , Rao K. Sridhar , Joshi Powrnima , Thiery Jean Paul , Dufour Sylvie , Pande Gopal
Published: January 2007

The number and distribution of lipid molecules, including cholesterol in particular, in the plasma membrane, may play a key role in regulating several physiological processes in cells. We investigated the role of membrane cholesterol in regulating cell shape, adhesion and motility. The acute depletion of cholesterol from the plasma membrane of cells that were well spread and motile on fibronectin caused the rounding of these cells and decreased their adhesion to and motility on fibronectin. These modifications were less pronounced in cells plated on laminin, vitronectin or plastic, indicating that cholesterol‐mediated changes in adhesion and motility are more specific for adhesion mediated by fibronectin‐specific integrins, such as α5β1. These changes were accompanied by remodeling of the actin cytoskeleton, the spatial reorganization of paxillin in the membrane, and changes to the dynamics of α5 integrin and paxillin‐rich focal adhesions. Levels of tyrosine phosphorylation at position 576/577 of FAK and Erk1/Erk2 MAP‐kinase activity levels were both lower in cholesterol‐depleted than in control cells. These levels normalized only on fibronectin when cholesterol was reincorporated into the cell membrane. Thus, membrane cholesterol content has a specific effect on certain signaling pathways specifically involved in regulating cell motility on fibronectin and organization of the actin cytoskeleton. Cell Motil. Cytoskeleton © 2007 Wiley‐Liss, Inc.