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41.
The purpose of this work was to measure viscosity of fluids at low microliter volumes by means of quartz crystal impedance
analysis. To achieve this, a novel setup was designed that allowed for measurement of viscosity at volumes of 8 to 10 μL.
The technique was based on the principle of electromechanical coupling of piezoelectric quartz crystals. The arrangement was
simple with measurement times ranging from 2 to 3 minutes. The crystal setup assembly did not impose any unwanted initial
stress on the unloaded quartz crystal. Quartz crystals of 5- and 10-MHz fundamental frequency were calibrated with glycerol-water
mixtures of known density and viscosity prior to viscosity measurements. True frequency shifts, for the purpose of this work,
were determined followed by viscosity measurement of aqueous solutions of sucrose, urea, PEG-400, glucose, and ethylene glycol
at 25°C±0.5°C. The measured viscosities were found to be reproducible and consistent with the values reported in the literature.
Minor inconsistencies in the measured resistance and frequency shifts did not affect the results significantly, and were found
to be experimental in origin rather than due to electrode surface roughness. Besides, as expected for a viscoelastic fluid,
PEG 8000 solutions, the calculated viscosities were found to be less than the reported values due to frequency dependence
of storage and loss modulus components of complex viscosity. From the results, it can be concluded that the present setup
can provide accurate assessment of viscosity of Newtonian fluids and also shows potential for analyzing non-Newtonian fluids
at low microliter volumes. 相似文献
42.
Su X Lawrence H Ganeshapillai D Cruttenden A Purohit A Reed MJ Vicker N Potter BV 《Bioorganic & medicinal chemistry》2004,12(16):4439-4457
Extensive structural modifications to the 18beta-glycyrrhetinic acid template are described and their effects on the SAR of the 11beta-hydroxysteroid dehydrogenase isozymes type 1 and 2 from the rat are investigated. Isoform selective inhibitors have been discovered and compound 7 N-(2-hydroxyethyl)-3beta-hydroxy-11-oxo-18beta-olean-12-en-30-oic acid amide is highlighted as a very potent selective inhibitor of 11beta-hydroxysteroid dehydrogenase 2 with an IC(50) = 4pM. 相似文献
43.
Srivastava N Sangita Ray S Singh MM Dwivedi A Kumar A 《Bioorganic & medicinal chemistry》2004,12(5):1011-1021
Diaryl naphthyl methanes and the corresponding 1, 2, 3, 4- and 5, 6, 7, 8-tetrahydro naphthyl methane derivatives have been synthesized as novel estrogen receptor binding ligands. The secondary and tertiary amino alkoxy derivatives of diaryl naphthyl and tetrahydro naphthyl methane interact with the estrogen receptor to elicit promising estrogenic, antiestrogenic and implantation inhibition activities in rats. The most active compounds in this series are 7, 9 and 20, cent percent active in preventing implantation in rats at 2.5 mgkg(-1) dose. 相似文献
44.
Regulation of estrogen synthesis in postmenopausal women 总被引:12,自引:0,他引:12
The decrease in ovarian estrogen production that occurs at the menopause may lead to an increase in peripheral aromatase activity. While estrogens can have beneficial effects on some body tissues, such as bone and the cardiovascular system, they also have a crucial role in supporting the growth and development of breast tumors. A number of factors, including interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), and prostaglandin E(2) (PGE(2)), which can stimulate aromatase activity, have now been identified. As plasma concentrations of some cytokines increase at the menopause, this may account for the increased peripheral aromatase activity that is detected in older women. Macrophages and lymphocytes which infiltrate breast tissue are now thought to be an important source of cytokines that can stimulate aromatase activity in this tissue. Studies, we have recently carried out, have suggested that the endogenous estrogen metabolite, 2-methoxy-estradiol, may be able to modulate the ability of cytokines and PGE(2) to stimulate aromatase activity. Understanding the role of endogenous estrogen metabolites in regulating estrogen synthesis may give rise to new strategies for the prevention or treatment of breast cancer. 相似文献
45.
Selective loss of innate CD4(+) V alpha 24 natural killer T cells in human immunodeficiency virus infection 总被引:1,自引:0,他引:1
Sandberg JK Fast NM Palacios EH Fennelly G Dobroszycki J Palumbo P Wiznia A Grant RM Bhardwaj N Rosenberg MG Nixon DF 《Journal of virology》2002,76(15):7528-7534
V alpha 24 natural killer T (NKT) cells are innate immune cells involved in regulation of immune tolerance, autoimmunity, and tumor immunity. However, the effect of human immunodeficiency virus type 1 (HIV-1) infection on these cells is unknown. Here, we report that the V alpha 24 NKT cells can be subdivided into CD4(+) or CD4(-) subsets that differ in their expression of the homing receptors CD62L and CD11a. Furthermore, both CD4(+) and CD4(-) NKT cells frequently express both CXCR4 and CCR5 HIV coreceptors. We find that the numbers of NKT cells are reduced in HIV-infected subjects with uncontrolled viremia and marked CD4(+) T-cell depletion. The number of CD4(+) NKT cells is inversely correlated with HIV load, indicating depletion of this subset. In contrast, CD4(-) NKT-cell numbers are unaffected in subjects with high viral loads. HIV infection experiments in vitro show preferential depletion of CD4(+) NKT cells relative to regular CD4(+) T cells, in particular with virus that uses the CCR5 coreceptor. Thus, HIV infection causes a selective loss of CD4(+) lymph node homing (CD62L(+)) NKT cells, with consequent skewing of the NKT-cell compartment to a predominantly CD4(-) CD62L(-) phenotype. These data indicate that the key immunoregulatory NKT-cell compartment is compromised in HIV-1-infected patients. 相似文献
46.
Bhardwaj D Hora B Singh N Puri SK Lalitha P Rupa P Chauhan VS 《FEMS immunology and medical microbiology》2002,34(1):33-43
Although several malaria vaccine candidate antigens have been identified, the most suitable methods for their delivery are still being investigated. In this regard, direct immunization with DNA encoding these vaccine target antigens is an attractive alternative. Here, we have investigated the immune responses to DNA immunization with three major vaccine target antigens: the apical membrane antigen-1 and the 19-kDa C-terminal fragment of merozoite surface protein-1 from the erythrocytic stage, and the thrombospondin-related adhesive protein from the pre-erythrocytic stage of Plasmodium cynomolgi in rhesus monkeys. Antigen-specific antibodies were developed in all the immunized monkeys and peripheral blood mononuclear cells from all immunized monkeys proliferated to different extents upon in vitro stimulation with the corresponding recombinant proteins. The immunized monkeys were challenged with P. cynomolgi sporozoites. All of the immunized animals developed infection but although there was no significant difference between the control and vaccinated animals in terms of pre-patent period, total duration of patency and primary peak parasitemia, the vaccinated animals had significantly lower secondary peak parasitemia than the control animals. 相似文献
47.
Pomper MG Musachio JL Zhang J Scheffel U Zhou Y Hilton J Maini A Dannals RF Wong DF Kozikowski AP 《Molecular imaging》2002,1(2):96-101
Imaging of glutamate carboxypeptidase II (GCP II), also known as N-acetylated alpha-linked L-amino dipeptidase (NAALADase), may enable study of glutamatergic transmission, prostate cancer, and tumor neovasculature in vivo. Our goal was to develop a probe for GCP II for use with positron emission tomography (PET). Radiosynthesis of 11C-MeCys-C(O)-Glu or 11C-(S)-2-[3-((R)-1-carboxy-2-methylsulfanyl-ethyl)-ureido]-pentanedioic acid (11C-MCG), an asymmetric urea and potent (Ki = 1.9 nM) inhibitor of GCP II, was performed by C-11 methylation of the free thiol. Biodistribution of 11C-MCG was assayed in mice, and quantitative PET was performed in a baboon. 11C-MCG was obtained in 16% radiochemical yield at the end of synthesis with specific radioactivities over 167 GBq/mmol (4000 Ci/mmol) within 30 min after the end of bombardment. At 30 min postinjection, 11C-MCG showed 33.0 +/- 5.1%, 0.4 +/- 0.1%, and 1.1 +/- 0.2% ID/g in mouse kidney (target tissue), muscle, and blood, respectively. Little radioactivity gained access to the brain. Blockade with unlabeled MCG or 2-(phosphonomethyl)pentanedioic acid (PMPA), another potent inhibitor of GCP II, provided sevenfold and threefold reductions, respectively, in binding to target tissue. For PET, distribution volumes (DVs) were 1.38 then 0.87 pre- and postblocker (PMPA). Little metabolism of 11C-MCG occurred in the mouse or baboon. These results suggest that 11C-MCG may be useful for imaging GCP II in the periphery. 相似文献
48.
Sharma RN Bhardwaj A Behera D Khanduja KL 《Indian journal of biochemistry & biophysics》2002,39(2):124-129
Superoxide anion (O2.-) and hydrogen peroxide (H2O2) production was significantly higher in blood neutrophils (PMNs) of patients with lung cancer and non-malignant lung diseases when compared to the controls (p<0.001). Superoxide dismutase (SOD) activity was significantly decreased in PMNs of patients with lung cancer (p<0.001). Similarly, catalase and glutathione peroxidase (GPx) activities were lower in PMNs of lung cancer patients as compared to non-malignant lung diseases and controls. There was an increase in HMP shunt activity as measured by rate of formation of 14CO2 from [1-14C]-glucose in PMNs of lung cancer patients. Modifications in the antioxidant defense system in PMNs of malignant and nonmalignant lung diseases, the changes being more in the malignancy are indicated. 相似文献
49.
Summary: PGAGENE is a web-based gene-specific genomic data search engine, which allows users to search over 5.9 million pieces of collective genetic and genomic data from the NHLBI supported Programs for Genomic Applications. This data includes microarray measurements, SNPs, and mutations, and data may be found using symbols, parts of gene names or products, Affymetrix probe IDs, GenBank accession numbers, UniGene IDs, dbSNP IDs, and others. The PGAGENE indexing agent periodically maps all publicly available gene-specific PGA data onto LocusLink using dynamically generated cross-referencing tables. 相似文献
50.
Binz PA Abdi F Affolter M Allard L Barblan J Bhardwaj S Bienvenut WV Bulet P Burgess J Carrette O Corthals G Delalande F Diemer H Favreau P Giuliano E Gueguen Y Guillaume E Hahner S Man P Michalet S Neri D Noukakis D Palagi P Paroutaud P Pimenta DC Quadroni M Resemann A Richert S Rybak J Sanchez JC Scherl A Scheurer S Schweiger Hufnagel U Siethoff C Suckau D van Dorsselaer A Wagner Redeker W Walter N Stöcklin R 《Proteomics》2003,3(8):1562-1566
After the success of the mass spectrometry (MS) round table that was held at the first Swiss Proteomics Society congress (SPS'01) in Geneva, the SPS has organized a proteomics application exercise and allocated a full session at the SPS'02 congress. The main objective was to encourage the exchange of expertise in protein identification, with a focus on the use of mass spectrometry, and to create a bridge between the users' questions and the instrument providers' solutions. Two samples were sent to fifteen interested labs, including academic groups and MS hardware providers. Participants were asked to identify and partially characterize the samples. They consisted of a complex mixture of peptide/proteins (sample A) and an almost pure recombinant peptide carrying post-translational modifications (sample B). Sample A was an extract of snake venom from the species Bothrops jararaca. Sample B was a recombinant and modified peptide derived from the shrimp Penaeus vannamei penaeidin 3a. The eight labs that returned results reported the use of a wide range of MS instrumentation and techniques. They mentioned a variety of time and manpower allocations. The origin of sample A was generally identified together with a number of database protein entries. The difficulty of the sample identification lay in the incomplete knowledge of the Bothrops species genome sequence and is discussed. Sample B was generally and correctly identified as penaeidin. However, only one group reported the full primary structure. Interestingly, the approaches were again varied and are discussed in the text. 相似文献