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C Wang

Publications and source records attributed to C Wang.

At least 91 records · Page 5Linked to original sources
PubMed2003

Application of high-performance liquid chromatography-mass spectrometry to detection of diuretics in human urine.

A rapid, sensitive and reliable high-performance liquid chromatographic-mass spectrometric method for the detection of 25 diuretics in human urine has been developed. Atmosphere pressure chemical ionization (APCI) and electrospray ionization (ESI) modes were evaluated. A 2-ml volume of urine was extracted under basic conditions and separated on an Agilent Zorbax SB-C(18) column (150 x 2.1 mm, 5 microm). The mobile phase consisted of formic ammonium-formic acid buffer (pH 3.5) and acetonitrile. The effects of capillary temperature, sheath gas pressure and compositions of mobile phase on the sensitivity were studied. The recoveries of most of the diuretics were 75-95%. In the full scan mode, the limits of detection of the 25 diuretics were 0.25-25 ng/ml for APCI and 0.6-250 ng/ml for ESI. Under the optimal conditions, 14 diuretics from authentic urine samples were detected successfully by LC-APCI-MS. To obtain more fragmentation information on the chemical structure for positive confirmation, tandem mass analysis was also investigated.

Chromatography, High Pressure Liquid↗
PubMed2003

Liquid chromatography-tandem mass spectrometry assay for human serum testosterone and trideuterated testosterone.

A liquid chromatography tandem mass spectrometry assay for serum testosterone (T) and trideuterated testosterone (d(3)T) was developed in order to support clinical research studies that determine the pharmacokinetics, production rate, and clearance of testosterone by administration of trideuterated testosterone. After adding 19-nortestosterone as the internal standard (I.S.), sodium acetate buffer, and ether, to a serum aliquot, the mixture was shaken and centrifuged, and the ether was dried. The extract was reconstituted in methanol and 15 microl was injected into a liquid chromatograph equipped with an autosampler and Applied Biosystems-Sciex API 300 triple quadrupole mass spectrometer operated in the positive ion mode. T, d(3)T, and I.S. were monitored with transitions m/z 289 to m/z 97, m/z 292 to m/z 97, and m/z 275 to m/z 109, respectively. The two calibration curves were linear over the entire measurement range of 0-20 ng/ml for T and 0-2.0 ng/ml for d(3)T. The LOQs for T and d(3)T were 0.5 ng/ml and 0.05 ng/ml. The recoveries for T and d(3)T were 91.5 and 96.4%. For T at 1.25 ng/ml and 4.0 ng/ml, the intra-day precision (RSD, %) was 3.9 and 4.3% and intra-day accuracy 0.01 and 4.5%, respectively. The inter-day precision at these levels was 5.3 and 5.4% and inter-day accuracy was 1.9 and 0.3%. For d(3)T at 0.125 ng/ml and 0.4 ng/ml, the intra-day precision (RSD, %) was 2.8 and 8.3% and intra-day accuracy was 1.8 and 5.6%. The inter-day precision at these levels was 10.0 and 7.6% and inter-day accuracy was 5.7 and 3.4%. The concentrations of T in the 38 healthy subjects ranged from 2.5 to 14.0 ng/ml (mean 6.2 ng/ml).

Calibration↗
PubMed2003

Oligodendrocyte progenitor migration in response to injury of glial monolayers requires the polysialic neural cell-adhesion molecule.

Injury to the nervous system results in reactive astrogliosis that is a critical determinant of neuronal regeneration. To analyze glial responses to mechanical injury and the role of the polysialic neural cell adhesion molecule (PSA-NCAM) in this process, we established primary glia cultures from newborn rat cerebral cortex. Scratching a confluent monolayer of primary glial cells resulted in two major events: rapid migration of oligodendrocyte progenitor-like (O-2A) cells into the wounded area and development of polarized morphology of type 1 astrocytes at the wound edge. Migrating O-2A progenitors had a bipolar morphology and exhibited A2B5 and O4 immunolabeling. Once these cells were established inside the wounded area, they lost A2B5 immunoreactivity and differentiated into glial fibrillary acidic protein-positive astrocytes. Migrating O-2A cells expressed PSA-NCAM, but type 1 astrocytes at the wound edge did not. Treatment of wounded cultures with Endo-N, which specifically removes PSA from the surface of cells, resulted in a significant decrease in O-2A cell migration into the wounded area and completely blocked the wound closure. Video time-lapse analysis showed that, in the presence of Endo-N, O-2A cells remained motile and migrated short distances but did not move away from the monolayer. These results demonstrate that O-2A progenitors contribute to reactive astrogliosis in culture and that PSA-NCAM is involved in this process by regulating cell migration.

Animals↗
PubMed2003

Area 21a of cat visual cortex strongly modulates neuronal activities in the superior colliculus.

We have examined the influence of cortico-tectal projections from one of the pattern-processing extrastriate visual cortical areas, area 21a, on the responses to visual stimuli of single neurones in the superior colliculi of adult cats. For this purpose area 21a was briefly inactivated by cooling to 10 degrees C using a Peltier device. Responses to visual stimuli before and during cooling as well as after rewarming ipsilateral area 21a were compared. In addition, in a subpopulation of collicular neurones we have studied the effects of reversible inactivation of ipsilateral striate cortex (area 17, area V1). When area 21a was cooled, the temperature of area 17 was kept at 36 degrees C and vice versa. In the majority of cases (41/65; 63%), irrespective of the velocity response profiles of collicular neurones, inactivation of area 21a resulted in a significant decrease in magnitude of responses of neurones in the ipsilateral colliculus and only in a small proportion of cells (2/65; 3.1%) was there a significant increase in the magnitude of responses. Inactivation of area 21a resulted in significant changes in the magnitude of responses of collicular cells located not only in the retino-recipient layers but also in the stratum griseum intermediale. In most cases, reversible inactivation of area 17 resulted in a greater reduction in the magnitude of responses of collicular cells than inactivation of area 21a. Reversible inactivation of area 21a also affected the direction selectivity indices and length tuning of most collicular cells tested.

Action Potentials↗
PubMed2003

Electrophoretic deposition of porous hydroxyapatite scaffold.

Bioactive porous hydroxyapatite (HA) scaffold was fabricated using electrophoretic deposition (EPD) technique in the present work. Bulk HA scaffold was achieved by repeated deposition. The green scaffold was sintered at 1200 degrees C to 82% of the theoretical density. Scanning electron microscopy examination and mercury porosimetry measurement have shown that the porosity remains interconnected and a range of pore size from several microns to hundreds of microns was obtained. X-ray diffraction analysis was performed and confirmed that there is no HA decomposition during the sintering process. Mechanical characterization has also shown that the EPD scaffold possesses excellent properties. Cell culturing experiment was carried out and the result shows that the scaffold bioactivity is not only dependent on the interconnectivity of the pores, but also the pore size.

Biocompatible Materials↗
PubMed2003

Colloidal characterization and electrophoretic deposition of hydroxyapatite on titanium substrate.

Hydroxyapatite (HA) powders were prepared by a modified chemical co-precipitation method and electrophoretically deposited onto a titanium tubular substrate. The zeta potential, electromobility and the particle size of the HA suspension was characterized at various pH values and the most stable and dispersed suspension condition was identified. Electrophoretic deposition of the HA particles on the titanium substrate was then carried out at this optimum suspension condition. Studies on deposition rate and examination on the microstructure of the sintered deposit were performed. The stoichiometry of the HA before and after sintering were also confirmed. The deposition experimental data obtained in the present work was also compared with theoretical model proposed in the literature. Lastly, the adhesion strength of the coating was also quantified using shear strength tests.

Journal Article↗
PubMed2003

Recombinant AAV serotype 1 transduction efficiency and tropism in the murine brain.

Recombinant adeno-associated virus serotype 2 (rAAV2) vectors have shown promise as therapeutic agents for neurologic disorders. However, intracerebral administration of this vector leads to preferential transduction of neurons and a restricted region of transgene expression. The recently developed rAAV vectors based upon nonserotype 2 viruses have the potential to overcome these limitations. Therefore, we directly compared a rAAV type 1 to a type 2 vector in the murine brain. The vectors were engineered to carry identical genomes (AAV2 terminal repeat elements flanking an enhanced green fluorescent protein expression cassette) and were administered by stereotaxic-guided intracerebral injection. We found that the rAAV1 vector (rAAV1-GFP) had a 13- to 35-fold greater transduction efficiency than that of the rAAV2 vector (rAAV2-GFP). Also, rAAV1-transduced cells were observed at a greater distance from the injection site than rAAV2-transduced cells. Neurons were the predominant cell type transduced by both vector types. However, in contrast to rAAV2-GFP, rAAV1-GFP was capable of transducing glial and ependymal cells. Thus, rAAV1-based vectors have biologic properties within the brain distinct from that of rAAV2. These differences might be capitalized upon to develop novel gene transfer strategies for neurologic disorders.

Animals↗
PubMed2003

The steady-state pharmacokinetics and bioequivalence of carprofen administered orally and subcutaneously in dogs.

Eighteen male Beagle dogs were randomized to oral (p.o.) or subcutaneous (s.c.) carprofen administration in a two-sequence, two-period crossover design with a 10-day washout between periods. Twenty-five milligrams of carprofen was administered p.o. or s.c. every 12 h for 7 days. Plasma concentrations of carprofen collected after the first and last treatments were determined by high-performance liquid chromatography. Carprofen concentration data were natural log transformed and geometric means were calculated for maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC0--12) following the first dose and Cmax and AUC0--12 following administration of the last dose. Formulations were considered bioequivalent if the 90% confidence interval (CI) of the mean difference for each variable between formulations were within -20% and 25% of the oral formulation. The mean Cmax and AUC0--12 were 16.9 microg/mL and 73.1 microg. h/mL, respectively, following a single oral dose and 8.0 microg/mL and 64.3 microg x h/mL, respectively, following a single s.c. injection. The 90% CI for Cmax (-56.8 to -48.7%) was outside of the bioequivalence criteria whereas the 90% CI for AUC0--12 (-16.3 to -7.5%) was within the bioequivalence criteria. At steady-state, the mean Cmax and AUC0--12 were 18.7 microg/mL and 101.9 microg x h/mL, respectively, following p.o. administration and 14.7 microg/mL and 111.0 microg x h/mL, respectively, following s.c. injection. The 90% CI was outside the bioequivalence criteria for Cmax (-30.8 to -10.8) but within the bioequivalence criteria for AUC0--12 (2.3-15.9%). The results of this study indicate that peak plasma concentrations of carprofen differ when administered p.o. and s.c., but that total drug exposure following a single dose and at steady-state are bioequivalent.

Administration, Oral↗
PubMed2003

Laminar differences in plasticity in area 17 following retinal lesions in kittens or adult cats.

Circumscribed retinal lesions in adult cats result in a reorganization of circuitry in area 17 such that neurons in the lesion projection zone (LPZ) can now be activated, not from their original receptive fields (RFs) but from regions of normal retina adjacent to the lesion ('ectopic' RFs). We have studied this phenomenon further by making circumscribed monocular retinal lesions in 8-week-old kittens and recording responses to visual stimuli of neurons in the LPZ of area 17 when these cats reached adulthood. These responses have been compared with those in adult-lesioned cats either of relatively short postlesion survival (2-24 weeks) or long postlesion survival (3.5-4.5 years). In both kitten-lesioned and adult-lesioned animals most LPZ neurons recorded from the supragranular layers (II and III) not only exhibited new ectopic RFs when stimuli were presented via the lesioned eye but the RF properties (e.g. the sizes of excitatory RFs, orientation and direction selectivities, velocity preferences and upper cut-off velocities) were often indistinguishable from those seen when stimuli were presented via the nonlesioned eye. Similarly, in both kitten-lesioned and adult-lesioned animals, most LPZ neurons recorded from the granular and infragranular layers (IV, V, VI), like those recorded from the supragranular layers, were binocular. However, in adult-lesioned but not in kitten-lesioned animals, the responses and the upper cut-off velocities of LPZ cells recorded from the granular and infragranular layers to stimuli presented via ectopic RFs tended to be, respectively, substantially weaker and lower than those for stimuli presented via the nonlesioned eye. The age-related laminar differences in reorganizational plasticity of cat striate cortex correlate with the lamino-temporal pattern of distribution of N-methyl-d-aspartate glutamate receptors in striate cortex.

Action Potentials↗
PubMed2003

Weight loss causes increased mortality: cons.

Short-term studies indicate that intentional weight loss (IWL) among obese persons significantly improves health variables that are often precursors or markers of chronic diseases (e.g. heart diseases, type-2 diabetes). Hence, it is logical to assume that IWL among obese persons would lead to increased longevity. On the whole, epidemiological studies, including recent ones that use conservative analytic approaches such as distinguishing between apparently IWL and unintentional weight loss (UWL), adjusting for potential confounders and excluding apparently unhealthy subjects, indicate that apparently IWL appears to neither increase nor decrease mortality rate. However, it is important to note that none of the existing studies were designed specifically to test the hypothesis that IWL reduces mortality rate, and given methodological problems, these studies do not provide a satisfactory way to address the body mass index (BMI)-mortality question. Several controlled clinical trials suggest that IWL may reduce mortality rate. However, even in these studies, it is important to acknowledge that subjects are randomized to conditions that produce more or less weight loss and not to distinct levels of weight loss per se. Nevertheless, while we await additional data from better designed studies, given our incomplete knowledge, we conclude that it seems more likely than not that IWL achieved by medically recommended methods does not increase and probably decreases mortality rate.

Animals↗
PubMed2003

Three-year follow-up of androgen treatment in hypogonadal men: preliminary report with testosterone gel.

Transdermal testosterone gels represent an effective alternative to injectable testosterone preparations. Short-term (6 months) data demonstrated positive effects on muscle, bone, fat, libido and mood. This report provides a preliminary analysis of longer-term treatment with a testosterone gel (AndroGel or Testogel) in a group of men aged 19-67 years of age. The positive effects of testosterone treatment on all of the above parameters persisted in this 3-year follow-up. The benefits occurred independent of age (equally in the older and younger subjects). The positive effects of transdermal testosterone gel on bone mineral density previously identified at 6 months of treatment, continued with time. The positive effects on bone mineral density were greater in the spine than the hip. There were minimal effects on lipid levels. Levels of prostate-specific antigen (PSA) increased with testosterone treatment but, in general, remained in the normal range. Three subjects (1.8%) were shown to have elevated PSA and biopsy-proven prostate cancer. It was not possible to determine if this incidence is above the background rate. Monitoring for prostate disease through PSA measurements and digital rectal examination is recommended for hypogonadal men in the older age groups when treated with testosterone.

Adult↗
PubMed2002

Potent neutralization of botulinum neurotoxin by recombinant oligoclonal antibody.

The botulinum neurotoxins (BoNTs) cause the paralytic human disease botulism and are one of the highest-risk threat agents for bioterrorism. To generate a pharmaceutical to prevent or treat botulism, monoclonal antibodies (mAbs) were generated by phage display and evaluated for neutralization of BoNT serotype A (BoNT/A) in vivo. Although no single mAb significantly neutralized toxin, a combination of three mAbs (oligoclonal Ab) neutralized 450,000 50% lethal doses of BoNT/A, a potency 90 times greater than human hyperimmune globulin. The potency of oligoclonal Ab was primarily due to a large increase in functional Ab binding affinity. The results indicate that the potency of the polyclonal humoral immune response can be deconvoluted to a few mAbs binding nonoverlapping epitopes, providing a route to drugs for preventing and treating botulism and diseases caused by other pathogens and biologic threat agents.

Animals↗
PubMed2002

Wnt-1 promotes neuronal differentiation and inhibits gliogenesis in P19 cells.

Wnt-1, the vertebrate counterpart of the Drosophila wingless gene, plays an important role in the early morphogenesis of neural tissues. In this report, we have shown that overexpression of Wnt-1 can direct embryonic carcinoma P19 cells to differentiate into neuron-like cells in the absence of retinoic acid. Immunocytochemistry showed that these cells expressed neuronal markers, such as the neurofilament (NF) and microtubule-associated protein 2 (MAP2), but failed to express the glial cell marker, glial fibrillary acidic protein (GFAP). RT-PCR revealed that two basic helix-loop-helix (bHLH) genes, Mash-1 and Ngn-1, were up-regulated during the differentiation stage of Wnt-1-overexpressing P19 cells. These results suggest that the Wnt-1 gene promotes neuronal differentiation and inhibits gliogenesis during the neural differentiation of P19 cells, and that neural bHLH genes might be involved in this process.

Animals↗
PubMed2002

The role of feline aminopeptidase N as a receptor for infectious bronchitis virus. Brief review.

Feline aminopeptidase N (fAPN) has been shown to serve as a receptor for feline, canine, porcine and human coronaviruses. Our objective was to determine if fAPN can serve as a receptor for infectious bronchitis virus (IBV). Feline kidney cells that express fAPN and hamster kidney fibroblasts that do not express fAPN were inoculated with IBV and monitored for replication by indirect fluorescent assay and confocal microscopy and in chicken embryonated eggs. The results showed that the feline cells were permissive to IBV but the hamster cells were not. The hamster cells became permissive to IBV after transfection with a fAPN cDNA suggesting that the feline APN molecule plays a role in IBV entry.

Animals↗
PubMed2002

Short-term responses of Oryzias latipes (Pisces: Adrianichthyidae) and Macrobrachium nipponense (Crustacea: Palaemonidae) to municipal and pharmaceutical waste water in Beijing, China: survival, behaviour, biochemical biomarkers.

Whole effluent toxicity was assessed for the fish Oryzias latipes and the prawn Macrobrachium nipponense for 18 h in a dilution series (0-66%) of the inflow and effluent of a municipal waste water treatment plant as well as waste water from a teramycin producing pharmaceutical industry, before, during and after a pilot laboratory purification process. The waste waters caused acute toxicity as measured by inhibition of light emission in the luminiscent bacterium Vibrio qingaiensis sp. nov. (Q67). EROD and aryl hydrocarbon hydroxylase activity in in vitro carp liver-cells showed a dose-dependent toxic response to the municipal waste water. Behavioural responses and time-to-death of fish and prawn, recorded online with the "Multispecies Freshwater Biomonitor" proved to be concentration- and time-dependent sensitive toxicity indicators in both types of waste water. Behaviour changed stepwise from normal activity to (increased or decreased) activity to more time spent on ventilation and finally to increased morbidity at higher concentration and time of exposure. The municipal waste water treatment plant managed to reduce toxicity to bacteria (Q67), prawn and fish. The pharmaceutical waste water treatment process still has to be improved, in order to reduce toxicity for fish and prawn.

Animals↗