PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 3 2007
Michael Kaszuba
Abstract Dynamic light scattering (DLS) is a technique used for measuring the size of molecules and particles undergoing Brownian motion by observing time-dependent fluctuations in the intensity of scattered light. The measurement of samples using conventional DLS instrumentation is limited to low concentrations due to the onset of a phenomenon called multiple scattering. The problems of multiple scattering have been addressed in a light scattering instrument incorporating non- invasive backscatter optics (NIBS). This novel optic arrangement maximizes the detection of scattered light while maintaining signal quality and allows for measurements of turbid samples. This paper discusses the ability of backscatter detection to accurately determine particle sizes at 1,%w/v sample concentrations and demonstrates the correct resolution of different size populations using a series of latex standard mixtures with known volume ratios. The concentration of 1,%w/v is much higher than can be measured on conventional dynamic light scattering instruments. [source]

Mechanisms determining cell membrane expression of different ,, TCR chain pairings

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2009
Laurent Boucontet
Abstract We investigated the ability of the most common TCR-, and , chains to express on the cell surface. V,1C,4 and V,7C,1 chains paired with all TCR-, chains tested, whereas V,4C,1 chains were found with V,4 and V,5, but not with V,2 or V,6 chains, and V,2C,2 chains were expressed only with V,5. Mapping studies showed that up to four polymorphic residues influence the different co-expressions of V,1 and V,2 chains with V, chains. Unexpectedly, these residues are not located in the canonical ,/, interface, but in the outer part of the ,, TCR complex exposed to the solvent. Expression of functional V,4 or V,6 chains in V,2/V,5+ cells or of functional V,2C,2 in V,1+ cells reduced cell-surface expression of the ,, TCR. Taken together, these data show that (i) the V,/V, repertoire of mouse ,, T cells is reduced by physical constraints in their associations. (ii) Lack of V,2/V, expression is due to the formation of aberrant TCR complexes, rather than to an intrinsic inability of the chains to pair and (iii) despite not being expressed at the cell surface, the presence of a functionally rearranged V,2 chain in ,, T cells results in reduced TCR levels. [source]

Some local and systemic immunological features of prepubertal periodontitis

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2001
T. Berglundh
Abstract Objectives: The aim of the present investigation was to study local (gingival) and systemic host defense characteristics in a sample of children exhibiting local prepubertal periodontitis (LPP). Material and methods: 2 groups of subjects were included in the present study. One group consisted of 11 children (9.5±2.0 years) with signs of periodontal disease (LPP group). A 2nd group comprised 21 adults (48.1±5.8 years) with advanced periodontal disease: adult periodontitis (AP) group. Gingival biopsies and a sample of peripheral blood were obtained in each individual of the AP group and in 7 out of the 11 subjects in the LPP group. The biopsies were prepared for morphometrical and immunohistochemical analysis and the blood samples prepared for immunohistochemical analysis. Results: The cellular infiltrates in the biopsies of the LPP group contained a larger proportion of lymphocytes and, in particular B cells, than was the case in the AP group. The TCR V,/V, gene expression in the lesions in the AP group was dominated by V, 17 and in the LPP group by V, 2. The content in peripheral blood of various lymphocyte sub-populations and TCR V,/V, gene expression in the 2 groups was almost similar. Conclusion: It is suggested that (i) the systemic host response in children with prepubertal periodontitis has many features in common with that seen in adult patients but that (ii) local defense mechanisms in the periodontitis lesion of LPP differ from those in adult periodontitis. [source]

Upregulation of Serotonin Transporter by Alcohol in Human Dendritic Cells: Possible Implication in Neuroimmune Deregulation

ALCOHOLISM, Issue 10 2009
Dakshayani Kadiyala Babu
Background:, Alcohol is the most widely abused substance and its chronic consumption causes neurobehavioral disorders. It has been shown that alcohol affects the function of immune cells. Dendritic cells (DC) serve as the first line of defense against infections and are known to accumulate neurotransmitters such as 5-hydroxytryptamine (5-HT). The enzyme monoamine oxidase-A (MAO-A) degrades 5-HT that is associated with clinical depression and other neurological disorders. 5-HT is selectively transported into neurons through the serotonin transporter (SERT), which is a member of the sodium- and chloride-dependent neurotransmitter transporter (SLC6) family. SERT also serves as a receptor for psychostimulant recreational drugs. It has been demonstrated that several drugs of abuse such as amphetamine and cocaine inhibit the SERT expression; however, the role of alcohol is yet to be elucidated. We hypothesize that alcohol can modulate SERT and MAO-A expression in DC, leading to reciprocal downregulation of 5-HT in extracellular medium. Methods:, Dendritic cells were treated with different concentrations (0.05% to 0.2%v/v) of alcohol for 24,72 hours and processed for SERT and MAO-A expression using Q-PCR and Western blots analysis. In addition, SERT function in DC treated with alcohol both in the presence and absence of imipramine, a SERT inhibitor was measured using 4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide uptake assay. 5-HT levels in culture supernatant and intracellular 5-hydroxy indole acetic acid (5-HIAA) and cyclic AMP were also quantitated using ELISA. Results:, Dendritic cells treated with 0.1% alcohol for 24 hours showed significant upregulation of SERT and MAO-A expression compared with untreated DC. We also observed that 0.1% alcohol enhanced the function of SERT and decreased extracellular 5-HT levels compared with untreated DC cultures, and this was associated with the elevation of intracellular 5-HIAA and cyclic AMP levels. Conclusions:, Our study suggests that alcohol upregulates SERT and MAO-A by elevating cyclic AMP, which may lead to decreased concentration of 5-HT in the extracellular medium. As 5-HT is a major neurotransmitter and an inflammatory mediator, its alcohol-mediated depletion may cause both neurological and immunological deregulation. [source]

Measurement of electrophoretic mobility of cardiomyocytes

ELECTROPHORESIS, Issue 21 2009
Ying Zhou
Abstract The electrophoretic mobility (EPM) of rat cardiomyocytes with or without the treatment of neuraminidase was studied by cell electrophoresis. The EPM was found to change over a range from 0 to 8.67,,m,s,1/V,cm,1, depending on ionic strength, transmembrane potential, pH value, and/or surface charges. It is interesting that zero EPM was observed but reverse of the mobility was not. These results suggested that the negative charges carried on the cardiomyocyte surface might comprehensively consist of surface sialic acid, plasmalemma proteins, phospholipids, and transmembrane potential. The aberrant electrical double layer formed between the carried negative charges and adions had a big adsorption layer and a diffusion layer whose sizes changed circularly, making only negative charges be carried on the surface of living cardiomyocytes. The special structures on the surface of cardiomyocytes probably play a considerable role in the process of cardiac electrical activity. [source]

A multifaceted imbalance of T cells with regulatory function characterizes type 1 autoimmune hepatitis,,

HEPATOLOGY, Issue 3 2010
Silvia Ferri
Immunotolerance is maintained by regulatory T cells (Tregs), including CD4+CD25hi, CD8+CD28,, ,,, and CD3+CD56+ [natural killer T (NKT)] cells. CD4+CD25hi cells are impaired in children with autoimmune hepatitis (AIH). Little is known about Tregs in adults with AIH. The aim of this study was to investigate the frequency and function of Treg subsets in adult patients with AIH during periods of active disease and remission. Forty-seven AIH patients (16 with active disease and 31 in remission) and 28 healthy controls were studied. Flow cytometry was used to evaluate surface markers and function-related intracellular molecules in ,,, CD8+CD28,, NKT, and CD4+CD25hi cells. CD4+CD25hi T cell function was determined by the ability to suppress proliferation and interferon gamma (IFN-,) production by CD4+CD25, target cells. Liver forkhead box P3,positive (FOXP3+) cells were sought by immunohistochemistry. In AIH patients, particularly during active disease, CD4+CD25hi T cells were fewer, expressed lower levels of FOXP3, and were less effective at inhibiting target cell proliferation versus healthy controls. Moreover, although the numbers of CD8+CD28, T cells were similar in AIH patients and healthy controls, NKT cells were numerically reduced, especially during active disease, and produced lower quantities of the immunoregulatory cytokine interleukin-4 versus controls. In contrast, ,, T cells in AIH patients were more numerous versus healthy controls and had an inverted V,1/V,2 ratio and higher IFN-, and granzyme B production; the latter was correlated to biochemical indices of liver damage. There were few FOXP3+ cells within the portal tract inflammatory infiltrate. Conclusion: Our data show that the defect in immunoregulation in adult AIH is complex, and ,, T cells are likely to be effectors of liver damage. (HEPATOLOGY 2010) [source]

Relationship of glutathione S-transferase genotypes with side-effects of pulsed cyclophosphamide therapy in patients with systemic lupus erythematosus

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 4 2006
Shilong Zhong
Aims Cyclophosphamide (CTX) is an established treatment of severe systemic lupus erythematosus (SLE). Cytotoxic CTX metabolites are mainly detoxified by multiple glutathione S-transferases (GSTs). However, data are lacking on the relationship between the short-term side-effects of CTX therapy and GST genotypes. In the present study, the effects of common GSTM1, GSTT1, and GSTP1 genetic mutations on the severity of myelosuppression, gastrointestinal (GI) toxicity, and infection incidences induced by pulsed CTX therapy were evaluated in patients SLE. Methods DNA was extracted from peripheral leucocytes in patients with confirmed SLE diagnosis (n = 102). GSTM1 and GSTT1 null mutations were analyzed by a polymerase chain reaction (PCR)-multiplex procedure, whereas the GSTP1 codon 105 polymorphism (Ile,Val) was analyzed by a PCR-restriction fragment length polymorphism (RFLP) assay. Results Our study demonstrated that SLE patients carrying the genotypes with GSTP1 codon 105 mutation [GSTP1*-105I/V (heterozygote) and GSTP1*-105 V/V (homozygote)] had an increased risk of myelotoxicity when treated with pulsed high-dose CTX therapy (Odds ratio (OR) 5.00, 95% confidence interval (CI) 1.96, 12.76); especially in patients younger than 30 years (OR 7.50, 95% CI 2.14, 26.24), or in patients treated with a total CTX dose greater than 1.0 g (OR 12.88, 95% CI 3.16, 52.57). Similarly, patients with these genotypes (GSTP1*I/V and GSTP1*V/V) also had an increased risk of GI toxicity when treated with an initial pulsed high-dose CTX regimen (OR 3.33, 95% CI 1.03, 10.79). However, GSTM1 and GSTT1 null mutations did not significantly alter the risks of these short-term side-effects of pulsed high-dose CTX therapy in SLE patients. Conclusions The GSTP1 codon 105 polymorphism, but not GSTM1 or GSTT1 null mutations, significantly increased the risks of short-term side-effects of pulsed high-dose CTX therapy in SLE patients. Because of the lack of selective substrates for a GST enzyme phenotyping study, timely detection of this mutation on codon 105 may assist in optimizing pulsed high-dose CTX therapy in SLE patients. [source]

Influence of pH, NaCl and pre-incubation on utilisation of surimi wash water in generation of antioxidative material by using the Maillard reaction

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2010
Chakree Thongraung
Summary Maillard reaction products (MRPs) were generated from reaction mixtures of surimi wash water (SWW) with glucose or fructose (5%w/v) heated at 95 °C for 2,12 h. The effects of pH, NaCl and pre-incubation of SWW on the Maillard reaction and antioxidant capacity of MRPs were investigated. The antioxidative capacity of MRPs was determined by measuring free DPPH° radical scavenging activity and reducing power. The highest colour intensity (OD420) as well as antioxidative capacity was noted in the reaction mixture containing fructose at pH 9.0. The addition of NaCl (0.5,2.5%w/v) caused reduction in browning intensity but enhanced antioxidative capacity of the MRPs. Pre-incubation of SWW at 45 °C for 4 h decreased soluble protein but increased the Maillard reaction and antioxidative capacity of MRPs. A positive effect of salt or pre-incubation of SWW on the antioxidative capacity of MRPs was not associated with the soluble protein content in the reaction mixture. [source]

Mechanisms determining cell membrane expression of different ,, TCR chain pairings

,, T-cell anergy in human immunodeficiency virus-infected persons with opportunistic infections and recovery after highly active antiretroviral therapy

IMMUNOLOGY, Issue 4 2000
F. Martini
Summary ,, T lymphocytes recognize non-peptidic microbial antigens without antigen processing and major histocompatibility complex (MHC) restriction, representing an early defence mechanism against invading pathogens. As a defective response to non-peptidic antigens was observed in human immunodeficiency virus-positive (HIV+) persons, the aims of this study were twofold: to analyse the incidence of ,, T-cell anergy in HIV+ patients with opportunistic infections/co-infections (HIV-OIC), and to investigate the role of highly active antiretroviral therapy (HAART) on ,, T-cell functions. Peripheral ,, T-cell distribution and in vitro reactivity to a non-peptidic mycobacterial antigen, isopentenyl pyrophosphate (IPP), were analysed. ,, T-cell subset distribution was altered more in HIV-OIC patients than in asymptomatic HIV+ subjects (HIV-ASY). Specifically, the V,2/V,1 ratio was inverted as a consequence of a decrease in V,2 T-cell number. Moreover, IPP-stimulated V,2 T cells from the HIV-OIC group displayed a major defect in interferon-, (IFN-,) production. Interestingly, HAART induced a sustained recovery of naive CD45RA+ and CD62L+ T cells and restored ,, T-cell function. Accordingly, in vitro CD45RA depletion resulted in ,, T-cell hyporesponsiveness. Altogether, the incidence of ,, T-cell anergy was increased in HIV-OIC patients and dependent on CD45RA helper function. Moreover, HAART was able to restore ,, T-cell reactivity, extending the immune recovery to non-peptidic microbial antigens. [source]

4336: Acute mechanical effect of riboflavin corneal cross-linking

ACTA OPHTHALMOLOGICA, Issue 2010
A PENNOS
Purpose To study the acute mechanical effect of corneal cross-linking in vitro. Methods Twenty porcine eyes were harvested from a local abattoire. The epithelium was removed using a rotating brush and corneal buttons having diameter of 8 mm were excised using a Barron's PKP trephine. The buttons were left immersed for four hours in Dextran solution (20%W/V) in order to regulate their hydration. The buttons were immersed in riboflafin 0.1% in dextran 20% and separated in two groups (10 buttons each) where one group was irradiated for 30 minutes with UV light while the other group was not irradiated and served as control. After treatment mechanical measurements were performed by means of a purposely-developed device featuring a stepping motor and a load cell. The motor shaft has a spherical tip that compresses the corneal button against a flat surface mounted on the load cell. The slope of force versus normalized deformation was recorded for each specimen. Results The control group had an average slope of 3.55 (± 1.81) while the irradiated group had 4.47 (±1.80). This difference was not statistically significant. (p=0.27) Conclusion This compressibility test did not reveal statistically significant changes between the two groups immediately after UV corneal cross-linking. It remains to be elucidated whether different tests (e.g. elongation) may yield different results. [source]

Influence of pH, NaCl and pre-incubation on utilisation of surimi wash water in generation of antioxidative material by using the Maillard reaction

Importance of murine V,1+,, T cells expressing interferon-, and interleukin-17A in innate protection against Listeria monocytogenes infection

IMMUNOLOGY, Issue 2 2008
Satoru Hamada
Summary Murine ,, T cells participate in the innate immune response against infection by an intracellular pathogen Listeria monocytogenes. V,1+,, T cells coexpressing V,6 are a major ,, T-cell subpopulation induced at an early stage of L. monocytogenes infection in the livers of infected mice. To investigate the protective role of the V,6/V,1+,, T cells against L. monocytogenes infection, V,1 gene-deficient (V,1,/,) mice were analysed because these mice selectively lacked a V,6/V,1+,, T-cell subpopulation in the L. monocytogenes -infected liver. The V,1,/, mice showed increased bacterial burden in the liver and spleen, and decreased survival rate at an early stage of L. monocytogenes infection when compared to wild-type mice. Histological examination showed abscess-like lesions and unorganized distribution of macrophages in the liver of the V,1,/, mice but not in the wild-type mice after L. monocytogenes infection. The V,6/V,1+,, T cells produced interferon-, and interleukin-17A. All the results suggest that murine V,6/V,1+,, T cells control the innate protective response against L. monocytogenes infection through production of the proinflammatory cytokines interferon-, and interleukin-17A in the infected liver. [source]

A Rodent Model of Alcoholic Heart Muscle Disease and Its Evaluation by Echocardiography

ALCOHOLISM, Issue 3 2001
Shann D. Kim
Background: Transthoracic echocardiography was used in a rodent animal model to determine whether long-term alcohol consumption (8 and 12 months) was associated with the development of a dilated cardiomyopathy. We also investigated whether alcohol-induced changes in cardiac structure corresponded to activation of the renin-angiotensin system and the natriuretic peptide (NP) system. Methods: Male rats received either the Lieber-DeCarli liquid alcohol diet (EtOH) (9%v/v) (n= 8) or control diet (CON) (n= 8). Echocardiography (echo) was used to determine left-ventricular (LV) dimensions, and isolated heart studies (Langendorff and atrium) were used to assess ex vivo contractility. Plasma and tissue angiotensin-I converting enzyme (ACE) activity was measured. Gene expression, plasma, and tissue levels of the NPs were determined by northern blot analysis and radioimmunoassay, respectively. Results: After 8 months of alcohol consumption, there was a trend for the end diastolic dimension, end systolic dimension, and LV mass to be greater in the 8 month EtOH group compared with the CON group. However, after 12 months of alcohol consumption, significant increases were found between the groups in several echo parameters. Tissue ACE activity (nmoles/min/mg protein) was greater in the 12 month EtOH group compared with the 12 month CON and 8 month EtOH group (p < 0.05). We found no differences between groups in gene expression (messenger RNA), plasma, and tissue levels of the NPs. Conclusions: Echocardiography revealed that 8 to 12 months of alcohol consumption was associated with the development of a dilated cardiomyopathy. However, this was not preceded by an increase in tissue ACE activity, and these changes occurred in the absence of increased plasma and LV tissue levels of the NPs. [source]

OASIS® wound matrix versus Hyaloskin® in the treatment of difficult-to-heal wounds of mixed arterial/venous aetiology

INTERNATIONAL WOUND JOURNAL, Issue 1 2007
Marco Romanelli
Abstract Mixed arterial/venous (A/V) ulcers are difficult to treat and slow to heal likely as a result of deficiencies in molecular and cellular elements in the wound bed. Recently, biomaterials have been developed that replace extracellular matrix (ECM) molecules and growth factors critical to the normal healing process. In this study, the effects of OASIS® and Hyaloskin® were evaluated to compare the effectiveness of these two ECM-based products in their ability to achieve complete wound healing of mixed A/V ulcers. After 16 weeks of treatment, patients in each group were evaluated on four criteria: complete wound healing, time to dressing change, pain and comfort. Complete wound closure was achieved in 82·6% of OASIS® -treated ulcers compared with 46·2% of Hyaloskin® -treated ulcers (P < 0·001). Statistically significant differences favouring the OASIS® treatment group were also reported for time to dressing change (P < 0·05), pain (P < 0·05) and patient comfort (P < 0·01). Overall, OASIS® was superior to Hyaloskin® for the treatment of patients with mixed A/V ulcers, a population in which standard treatment options largely consist of moist wound dressings and compression therapy is typically not an option. OASIS® is a useful and well-tolerated treatment for mixed A/V ulcers that has the potential to improve quality of life and reduce costs associated with standard of care. [source]

MRI and S-MRCP findings in patients with suspected chronic pancreatitis: Correlation with endoscopic pancreatic function testing (ePFT)

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010
N. Cem Balci MD
Abstract Purpose: To review magnetic resonance imaging (MRI) and secretin stimulated magnetic resonance cholangiopancreatography (S-MRCP) findings of patients with suspected chronic pancreatitis and compare them with endoscopic pancreatic function testing (ePFT). Materials and Methods: MRI and S-MRCP findings of 36 patients with clinically suspected chronic pancreatitis were reviewed. Baseline ductal changes, duodenal filling grades, and pancreatic duct caliber change (PDC) on S-MRCP, mean values of pancreatic anteroposterior (AP) diameter, signal intensity ratio (SIR) between pancreas and the spleen on T1-weighted fat saturated images, and arterial to venous (A/V) enhancement ratios were compared between groups of normal and abnormal pancreatic exocrine function determined by ePFT. Results: All patients (n = 24) with normal ePFT (HCO3 >80 mEq/L) had grade 3 normal duodenal filling. Patients with abnormal ePFT (HCO3 <80 mEq/L) (n = 12) had grade 1 (n = 1) and grade 2 (n = 11) diminished duodenal filling (P < 0.0001). PDC was 1.51 in the normal ePFT group versus 1.27 in the abnormal ePFT group (P = 0.01). No significant differences were found in terms of mean pancreatic AP diameter (21.8 vs. 19.8 cm), SIR (1.59 vs. 1.44), and A/V (1.08 vs. 1.01) between groups of normal/abnormal pancreatic exocrine function. Conclusion: Despite discrepancies between pancreatic exocrine function and the findings on standard MRI/MRCP, the S-MRCP findings are comparable to ePFT in the evaluation of chronic pancreatitis. J. Magn. Reson. Imaging 2010;31:601,606. © 2010 Wiley-Liss, Inc. [source]

Characterization of hepatitis B virus reverse transcriptase sequences in Chinese treatment naive patients

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8 2009
Yue Han
Abstract Background and Aims:, The hepatitis B virus (HBV) reverse transcriptase (RT) plays an important role in viral replication. The aim of the present study was to characterize profiles of the RT region and to construct a database for further studies. Methods:, Serum samples were obtained from 328 treatment naive patients chronically infected with HBV in five Chinese cities. Mutation status, genotypes and deep sequence analysis were carried out by amplifying and sequencing the RT region. Results:, The base usage in the RT region differed at the mono- and dinucleotide level and thymidine dominated. The higher the variability of the strain was, the more it replicated. No significant clustering was found between our HBV RT sequences and those isolated 10 years ago (achieved from genebank). Nucleotide analogue resistance related mutants exist. The M204V/I mutation was found in 1.8% of the strains, 1.2% had L180M+ M204V/I, 0.6% had A181T/V, and only one had all three mutations. Minor strain mutants were found in 9.3% of the samples studied. The genotype B patients made up 36.6% (88.7% B2) and were mostly found in southern China, 63.4% (92.2% C2) were genotype C, and only one was genotype D. The average age of HBeAg positive genotype B patients was 29.5 ± 10.4 years, for genotype C it was 36.1 ± 10.9 (P < 0.001). Conclusion:, Primarily antiviral resistance related mutant strains do exist in treatment naïve patients. Without antiviral pressure, HBV strains evolved at a normal speed. In depth sequence analysis implied that viral replication might be correlated with its variability, which needs to be further investigated. [source]

Influence of supported vanadium catalyst on ethylene polymerization reactions

POLYMER INTERNATIONAL, Issue 2 2008
Sutapa Ghosh
Abstract BACKGROUND: In the research area of homogeneous Ziegler,Natta olefin polymerization, classic vanadium catalyst systems have shown a number of favourable performances. These catalysts are useful for (i) the preparation of high molecular weight polymers with narrow molecular weight distributions, (ii) the preparation of ethylene/R -olefin copolymers with high R -olefin incorporation and (iii) the preparation of syndiotactic polypropylenes. In view of the above merits of vanadium-based catalysts for polymerization reactions, the development of well-defined single-site vanadium catalysts for polymerization reactions is presently an extremely important industrial goal. The main aim of this work was the synthesis and characterization of a heterogeneous low-coordinate non-metallocene (phenyl)imido vanadium catalyst, V(NAr)Cl3, and its utility for ethylene polymerization. RESULTS: Imido vanadium complex V(NAr)Cl3 was synthesized and immobilized onto a series of inorganic supports: SiO2, methylaluminoxane (MAO)-modified SiO2 (4.5 and 23 wt% Al/SiO2), SiO2 Al2O3, MgCl2, MCM-41 and MgO. Metal contents on the supported catalysts determined by X-ray fluorescence spectroscopy remained between 0.050 and 0.100 mmol V g,1 support. Thermal stability of the catalysts was determined by differential scanning calorimetry (DSC). Characterization of polyethylene was done by gel permeation chromatography and DSC. All catalyst systems were found to be active in ethylene polymerization in the presence of MAO or triisobutylaluminium/MAO mixture (Al/V = 1000). Catalyst activity was found to depend on the support nature, being between 7.5 and 80.0 kg PE (mol V),1 h,1. Finally, all catalyst systems were found to be reusable for up to three cycles. CONCLUSION: Best results were observed in the case of silica as support. Acid or basic supports afforded less active systems. In situ immobilization led to higher catalyst activity. The resulting polyethylenes in all experiments had ultrahigh molecular weight. Finally, this work explains the synthesis and characterization of reusable supported novel vanadium catalysts, which are useful in the synthesis of very high molecular weight ethylene polymers. Copyright © 2007 Society of Chemical Industry [source]

Cd8+/v,5.1+ large granular lymphocyte leukemia associated with autoimmune cytopenias, rheumatoid arthritis and vascular mammary skin lesions: successful response to 2-deoxycoformycin.

HEMATOLOGICAL ONCOLOGY, Issue 2 2002
E. Granjo
Abstract We report a case of CD8+/V,5.1+ T-cell large granular lymphocyte leukemia (T-LGL leukemia) presenting with mild lymphocytosis, severe autoimmune neutropenia, thrombocytopenia, polyarthritis and recurrent infections with a chronic disease course. Immunophenotyping showed an expansion of CD3+/TCR,,+/CD8+bright/CD11c+/CD57,/CD56, large granular lymphocytes with expression of the TCR-V,5.1 family. Southern blot analysis revealed a clonal rearrangement of the TCR ,-chain gene. Hematopoietic growth factors, high dose intravenous immunoglobulin and corticosteroids were of limited therapeutic benefit to correct the cytopenias. During the disease course, the patient developed a severe cutaneous leg ulcer and bilateral vascular mammary skin lesions. Treatment with 2-deoxycoformycin resulted in both clinical and hematological complete responses, including the resolution of vascular skin lesions. Combined immuno-staining with relevant T-cell associated and anti-TCR-V, monoclonal antibodies proved to be a sensitive method to assess the therapeutic effect of 2-deoxycoformicin and to evaluate the residual disease. Copyright © 2002 John Wiley & Sons, Ltd. [source]

A refined technique for determining the respiratory gas exchange responses to anaerobic metabolism during progressive exercise , repeatability in a group of healthy men

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2004
Anita G. M. Wisén
Summary The respiratory gas exchange and ventilation during an incremental cycle exercise test were analysed in a group of 19 healthy, moderately fit men. Different computer algorithms were used to estimate the V,O2 values where: (i) the rate of V,CO2 increase just exceeds the rate of V,O2 increase (DX, derivative crossing), (ii) V,CO2/V,O2 = 1·00 (PX, point of crossing) and (iii) ventilation (V,E) increases disproportionately in relation to V,CO2 (PQ, point of V,CO2 equivalent rise). The DX and PQ measurements were analysed using a new approach employing polynomial regression and the value of PX was determined following low-pass filtration of raw data. The repeatability of the measurements was evaluated with a 5,6 week interval between the tests. The correlations between tests were 0·75 at DX, 0·85 at PX and 0·62 at PQ. The mean differences between the repeated tests were not statistically significant. The repeatability of V,O2, in absolute values expressed as ±2 SD of the differences between the tests, had values of 5·0, 6·1 and 9·5 ml min,1 kg,1 for DX, PX and PQ, respectively. The mean value of V,O2 for each measurement point expressed as a percentage of V,O2max was 54% at DX, 68% at PX and 70% at PQ. The most common sequence of the measured values was DX < PX < PQ, but the sequence DX < PQ < PX was also observed. It is concluded that the gas exchange responses to developing anaerobic metabolism during progressive exercise can be characterized by a series of thresholds. However, the considerable variation in absolute values in the two testing occasions requires further attention. [source]

Cd8+/v,5.1+ large granular lymphocyte leukemia associated with autoimmune cytopenias, rheumatoid arthritis and vascular mammary skin lesions: successful response to 2-deoxycoformycin.

Ionic dialysance: Principle and review of its clinical relevance for quantification of hemodialysis efficiency

HEMODIALYSIS INTERNATIONAL, Issue 2 2005
Lucile Mercadal
Ionic dialysance (D) is an online measured variable now available on several dialysis monitors to evaluate small-solute clearance. Based on conductivity measurements in the inlet and outlet dialysate, the principle of the measurement and the different measurement methods are described. Studies that have evaluated the reliability of ionic dialysance to assess dialysis efficiency are discussed. These studies are divided into two groups: the first comparing ionic dialysance to urea clearance and the second comparing Dt/V to Kt/Vurea, in which the uncertainties of the measurement of Vurea could have misrepresented the relationship between Dt/V and Kt/Vurea. When Kt/Vurea via the Daugirdas second-generation equation taking the rebound into account is considered, slight,even nonsignificant,differences are evidenced between Kt/Vurea and Dt/V. Therefore, ionic dialysance should be considered as a valid measure in future guidelines for dialysis efficiency. [source]

Exercise test mode dependency for ventilatory efficiency in women but not men

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 2 2006
James A. Davis
Summary Ventilatory efficiency is commonly defined as the level of ventilation V,E at a given carbon dioxide output (V,CO2). The slope of the V,E versus V,CO2 relationship and the lowest V,E/V,CO2 are two ventilatory efficiency indices that can be measured during cardiopulmonary exercise testing (CPET). A possible CPET mode dependency for these indices was evaluated in healthy men and women. Also evaluated was the relationship between these two indices as, in theory, V,E/V,CO2 falls hyperbolically towards an asymptote that numerically equals the V,E versus V,CO2 slope at exercise levels below the ones that cause respiratory compensation for metabolic acidosis. Twenty-eight healthy subjects (14 men) underwent treadmill and cycle ergometer CPET on different days. Ventilation and the gas fractions for oxygen and CO2 were measured with a vacumed metabolic cart. In men, paired t -test analysis failed to find a mode difference for either ventilatory efficiency index but the opposite was true in the women as each woman had higher values for both indices on the treadmill. For men, the lowest V,E/V,CO2 was larger than the V,E versus V,CO2 slope by 1·3 on the treadmill and 0·8 on the cycle ergometer. The corresponding values for women were 1·7 and 1·4. We conclude that in healthy subjects, women, but not men, demonstrate a mode dependency for the two ventilatory efficiency indices investigated in this study. Furthermore, our results are consistent with the theoretical expectation that the lowest V,E/V,CO2 has a numerical value just above the asymptote of the V,E/V,CO2 versus V,CO2 relationship. [source]

GH responsiveness in a large multinational cohort of SGA children with short stature (NESTEGG) is related to the exon 3 GHR polymorphism

CLINICAL ENDOCRINOLOGY, Issue 3 2007
M. Tauber
Summary Objective, The polymorphic deletion of exon 3 of the GH receptor (d3-GHR) has recently been linked to the magnitude of growth response to recombinant human GH (rhGH) therapy in short children with or without GH deficiency. We investigated this association in a large multinational cohort from the Network of European Studies of Genes in Growth (NESTEGG), comprising short children born small for gestational age (SGA). Design, The study included short prepubertal SGA children treated with rhGH for 1 or 2 years. Population, Two hundred and forty white Caucasian SGA children (138 male, 102 female) aged 6·6 ± 2·3 years with a height at ,3·0 ± 0·7 SDS at start of rhGH treatment; 193 ethnically matched controls. Methods, The GHR polymorphism (fl/fl, fl/d3 or d3/d3) was genotyped by polymerase chain reaction (PCR) multiplex assay. Growth velocity (G/V) in cm/year and changes in GV during the first and second year of rhGH treatment were evaluated. Results, The change in GV was significantly greater in SGA children carrying one or two copies of the d3-GHR allele (P = 0·038 for the first year and P = 0·041 for the second year of GH treatment), but the change in height was not significantly different. Birthweight was significantly lower in SGA children with the d3/d3 genotype than in SGA children with the fl/fl genotype (P = 0·034) and in those with the fl/d3 genotype (P = 0·016). Conclusion, Our data, based on a large cohort, showed that the exon 3 GHR polymorphism is associated with responsiveness to rhGH treatment in SGA children with short stature. [source]

Three-dimensional VS profiling using microtremors in Kushiro, Japan

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2008
Hiroshi Arai
Abstract A practical method is presented for determining three-dimensional S-wave velocity (VS) profile from microtremor measurements. Frequency,wave number (f,k) spectral analyses of microtremor array records are combined, for this purpose, with microtremor horizontal-to-vertical (H/V) spectral ratio techniques. To demonstrate the effectiveness of the proposed method, microtremor measurements using arrays of sensors were conducted at six sites in the city of Kushiro, Japan. The spectral analyses of the array records yield dispersion characteristics of Rayleigh waves and H/V spectra of surface waves, and joint inversion of these data results in VS profiles down to bedrock at the sites. Conventional microtremor measurements were performed at 230 stations within Kushiro city, resulting in the H/V spectra within the city. Three-dimensional VS structure is then estimated from inversion of the H/V spectra with the VS values determined from the microtremor array data. This reveals three-dimensional VS profile of Kushiro city, together with an unknown hidden valley that crosses the central part of the city. The estimated VS profile is consistent with available velocity logs and results of subsequent borings, indicating the effectiveness of the proposed method. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Seismic microzonation of the greater Bangkok area using microtremor observations

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2004
Rabin Tuladhar
Abstract Bangkok, the capital city of Thailand, is located at a remote distance from seismic sources. However, it has a substantial risk from these distant earthquakes due to the ability of the underlying soft clay to amplify ground motions. It is therefore imperative to conduct a detailed seismic hazard assessment of the area. Seismic microzonation of big cities, like Bangkok, provides a basis for site-specific hazard analysis, which can assist in systematic earthquake mitigation programs. In this study, a seismic microzonation map for the greater Bangkok area is constructed using microtremor observations. Microtremor observations were carried out at more than 150 sites in the greater Bangkok area. The predominant periods of the ground were determined from the horizontal-to-vertical (H/V) spectral ratio technique. A microzonation map was then developed for the greater Bangkok area based on the observations. Moreover, the transfer functions were calculated for the soil profile at eight sites, using the computer program SHAKE91, to validate the results from the microtremor analysis. The areas near the Gulf of Thailand, underlaid by a thick soft clay layer, were found to have long natural periods ranging from 0.8s to 1.2s. However, the areas outside the lower central plain have shorter predominant periods of less than 0.4s. The study shows that there is a great possibility of long-period ground vibration in Bangkok, especially in the areas near the Gulf of Thailand. This may have severe effects on long-period structures, such as high-rise buildings and long-span bridges. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Shear wave velocity model of the Santiago de Chile basin derived from ambient noise measurements: a comparison of proxies for seismic site conditions and amplification

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2010
Marco Pilz
SUMMARY We determined a high-resolution 3-D S -wave velocity model for a 26 km × 12 km area in the northern part of the basin of Santiago de Chile. To reach this goal, we used microtremor recordings at 125 sites for deriving the horizontal-to-vertical (H/V) spectral ratios that we inverted to retrieve local S -wave velocity profiles. In the inversion procedure, we used additional geological and geophysical constraints and values of the thickness of the sedimentary cover already determined by gravimetric measurements, which were found to vary substantially over short distances in the investigated area. The resulting model was derived by interpolation with a kriging technique between the single S -wave velocity profiles and shows locally good agreement with the few existing velocity profile data, but allows the entire area, as well as deeper parts of the basin, to be represented in greater detail. The wealth of available data allowed us to check if any correlation between the S -wave velocity in the uppermost 30 m (v30S) and the slope of topography, a new technique recently proposed by Wald and Allen, exists on a local scale. We observed that while one lithology might provide a greater scatter in the velocity values for the investigated area, almost no correlation between topographic gradient and calculated v30S exists, whereas a better link is found between v30S and the local geology. Finally, we compared the v30S distribution with the MSK intensities for the 1985 Valparaiso event, pointing out that high intensities are found where the expected v30S values are low and over a thick sedimentary cover. Although this evidence cannot be generalized for all possible earthquakes, it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the Santiago basin. [source]

Resonant Tunneling Processes along Conjugated Molecular Wires: A Quantum-Chemical Description

ADVANCED FUNCTIONAL MATERIALS, Issue 11-12 2002
Y. Karzazi
Abstract Molecular electronics research is a very active area in the field of nanotechnology. It is now well established that individual or self-assembled molecules can behave as nanoscopic switches in transistor and diode configurations. Molecular wires inserted into nanopores and contacted by two metallic electrodes can also be used as active elements for the fabrication of resonant tunneling diodes (RTDs). The RTD current/voltage (I/V) characteristics can display a negative differential resistance (NDR) behavior (i.e., a negative slope in the I/V curve) for reasons that are not yet fully understood. Here we describe a possible mechanism at the quantum-chemical level that is based on conformational effects and accounts for the experimental observation of strong NDR signatures in substituted phenylene ethynylene oligomers. The occurrence of a peak current in the I/V curves is rationalized by analyzing the evolution of the one-electron structure of the molecular wires upon application of a static electric field aligned along the molecular axis (the field simulates the driving voltage applied between the two electrodes in the RTD devices). The results of our calculations provide a general basis to develop strategies for the design of molecular wires displaying an NDR behavior. [source]

Relationship of glutathione S-transferase genotypes with side-effects of pulsed cyclophosphamide therapy in patients with systemic lupus erythematosus

Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OVIV(,-Ooxo)(,-Ophen)VVO]2+ Core: Synthesis, EPR Spectra, Molecular and Electronic Structure

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006
Amrita Mondal
Abstract Binuclear mixed valence oxovanadium(IV/v) complexes of general formula [V2O3L] containing a [OVIV(,-Ooxo)(,-Ophen)VVO]2+ core have been synthesised using conformationally labile N4O3 -coordinating heptadentate ligands (H3L). The X-ray structure of one complex has been examined. Solution EPR spectra revealed that the unpaired electron of the complexes is delocalised between the two vanadium centres. The simulated EPR spectrum of one complex confirms this experimental observation. DFT studies have been performed using crystallographic coordinates in order to obtain further insight into the electronic structure of this type of molecule. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]