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Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 433 records · Page 24Linked to original sources
PubMed1999

In vitro and in vivo studies of 1H NMR visibility to detect deoxyhemoglobin and deoxymyoglobin signals in myocardium.

1H nuclear magnetic resonance (NMR) spectroscopy can be used noninvasively to detect the proximal histidyl N delta proton signals of deoxymyoglobin in the myocardium. However, the quantification of deoxymyoglobin is based on the assumption that the deoxymyoglobin signal detected is not contaminated by the deoxyhemoglobin signals contributed from the blood. The purpose of this study was to conduct in vitro and in vivo 1H NMR studies to examine the in vivo NMR visibility of deoxyhemoglobin in the myocardium. The results demonstrate that the NMR visibility of alpha and beta subunits of deoxyhemoglobin is sensitive to the pulse width for spin excitation because of short T2 relaxation times, and they are not NMR visible in the canine myocardium in vivo at 4.7 T when a 0.5-1.0 msec long Gaussian excitation pulse is used. Therefore, the resonance peak detected at approximately 72 ppm (relative to the water resonance) in the ischemic canine myocardium in vivo is dominated by deoxymyoglobin.

Animals↗
PubMed1999

Role of intercellular adhesion molecule-1 and lymphocyte function-associated antigen-1 during nonsuppurative destructive cholangitis in a mouse graft-versus-host disease model.

Intercellular adhesion molecule-1 (ICAM-1) is expressed abnormally on the bile duct epithelium during the course of primary biliary cirrhosis (PBC), but the importance of ICAM-1 and its lymphocyte function-associated antigen-1 (LFA-1) receptor during the course of nonsuppurative destructive cholangitis (NSDC) has not been defined. To address this question, we defined the relationship between ICAM-1 on the intrahepatic bile duct epithelium and the evolution of NSDC lesions in a mouse graft-versus-host disease (GVHD) model. We also determined the effects of anti-ICAM-1 and anti-LFA-1 treatments on NSDC, intrahepatic lymphokine production, and the homing of lymphocytes to the livers of GVHD mice. ICAM-1 was initially detected on the bile duct epithelium and portal vein endothelium on day 7 of GVHD. There was a significant positive correlation between the intensity of ICAM-1 staining and histological bile duct damage (r =.58, P <.05) between day 3 and 28. Treatment with anti-ICAM-1 (but not anti-LFA-1) decreased both the mean grades of portal inflammation (P =.003) and NSDC (P =.002) lesions compared with control immunoglobulin G (IgG) treatments. Combined treatment with anti-ICAM-1 and anti-LFA-1 caused a further decrease in the amount of portal inflammation and bile duct damage compared with anti-ICAM-1, alone (P =.02). Anti-ICAM-1 treatment also decreased both the percentage of T cells and the production of interleukin-2 (IL-2) and IL-12 in the liver (P <.01), but had no effect on IL-4, IL-10, and interferon gamma. Neither anti-ICAM-1 nor anti-LFA-1 prevented lymphocytes from homing to the liver. These results indicate that both ICAM-1 and LFA-1 are important to the pathogenesis of NSDC.

Animals↗
PubMed1999

Mapping brain metabolites using a double echo-filter metabolite imaging (DEFMI) technique.

A double echo-filter metabolite imaging (DEFMI) technique was developed for spatial mapping of low-concentration metabolites in the human brain. This imaging technique simultaneously acquires two images from two individual metabolites, respectively, using conventional imaging acquisition. It provides (i) efficient water and lipid suppressions, (ii) the capability of collecting high-resolution metabolite images within a short time and creating a ratio image from two interesting metabolites within a single experiment, and (iii) flexibility and simplicity for experimental setup and data processing. The technique was examined by both phantom and human brain experiments at 4 Tesla. The results reveal that the DEFMI technique is promising for applications in metabolism studies aimed at investigating physiological and pathological questions.

Aspartic Acid↗
PubMed1999

Microwave Spectra of the Methylpolyynes CH(3)(C&tbond;C)(6)H and CH(3)(C&tbond;C)(7)H.

Two new methylpolyynes, CH(3)(C&tbond;C)(6)H (tridecahexayne) and CH(3)(C&tbond;C)(7)H (pentadecaheptayne), have been detected in a supersonic molecular beam by Fourier transform microwave spectroscopy. A total of 20 transitions of CH(3)(C&tbond;C)(6)H in the K = 0 and 1 rotational ladders and 8 transitions of CH(3)(C&tbond;C)(7)H in the K = 0 ladder were observed between 5 and 11 GHz, allowing for both molecules precise determination of rotational and centrifugal distortion constants. Like other long carbon chains of similar length, the rotational constants of the two new methylpolyynes are well predicted by extrapolation from the shorter members of the sequence; the addition of successive C(2) units evidently little perturbs the structure of the rest of the molecule. Centrifugal distortion is well described by the same semiclassical model that works well for the cyanopolyynes, one which treats a carbon chain as a thin elastic rod with a Young's modulus independent of length. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Quantitative study on expression of p16 multiple tumor suppressor gene in salivary gland neoplasm.

The expression of p16 gene in normal salivary acini, benign tumors and carcinomas were microscopically and quantitatively observed by using immunohistochemical method LSAB and CMIASWIN methods. The expression of p16 gene were found in all 3 groups. The positive unit (PU) was higher in tumor group and cancer group than that in normal group (P < 0.01). Furthermore, the PU of p16 was stronger in cytoplasm than in nucleus. Malignant tumors and acini surrounding the tumor revealed strong positives and weak positives respectively. The PU of p16 gene was higher in deep lobe of recurrent parotid neoplasm with incomplete capsule than that in shallow lobe of primary parotid neoplasm with complete capsule. The findings suggests that p16 gene plays an equally important role in the salivary gland tumors and tumors in other part of the body.

Adenoma, Pleomorphic↗
PubMed1999

Effects of concurrent use of rh-IFN-gamma and curcumin on the anti-proliferative capacity of HL-60 cells.

To understand the effect of rh-IFN-gamma on the ability of curcumin to kill HL-60 cells in vitro, the myeloid leukemic cell line HL-60 was studied by using cell culture. BrdU incorporation rate was examined by SABC, DNA content was determined by flow cytometry and apoptotic cell percentage was determined by TUNEL method. The results showed that curcumin inhibited proliferation of leukemic cells in a dose-dependent manner. When HL-60 cells were treated with 25 mumol curcumin for 24 h, the proliferative inhibitory rate was 43.75 +/- 2.00%. This effect could be enhanced obviously by IFN-gamma, the combined proliferative inhibitory rate increased to over 80%. The 5-BrdU incorporation rate and the distribution of DNA content indicated that curcumin could arrest cells in the G1/G0 and G2/M phase of cell cycle. At the same time, the sub-G1 peak (apoptotic peak) appeared. After IFN-gamma combined with curcumin, DNA synthesis rate decreased further. It showed a significant difference when compared with single drug group (P < 0.05). Meanwhile, sub-G1 peak also increased. The percentage of TUNEL positive cells was aslo increased. It is concluded that IFN-gamma can enhance the antiproliferative ability of curcumin against HL-60 cells.

Antineoplastic Agents↗
PubMed1999

The clinical application of computerized three-dimensional mimic operation for maxillofacial bone tumor.

Facial bone, as the frame to support maxillofacial region and with several sinuses and cavities, is structurally complicated and the maxillofacial tumors, benign or malignant, in this region usually grows into the deep tissues, sinus-cavities and orbit and destroys the bone. In this study, the maxillofacial tumors were subjected to a mimic operation on a computer following CT scanning and 3-dimensional reconstruction. The data similar to those of real operation were obtained, which could be used for developing operative plans. As compared with data on the basis of conditions in the real operation, computerized mimic operation reflected the real conditions during operation. Computerized mimic operation is valuable for the preoperative planning and the prediction of probable intraoperative events.

Bone Neoplasms↗
PubMed1999

Liver and peripheral blood mononuclear cells are not major sites for GB virus-C/hepatitis G virus replication.

The pathogenesis and replication sites of GB virus-C/hepatitis G virus (GBV-C/HGV) in humans remain unclear. The presence of GBV-C/HGV and hepatitis C virus (HCV) RNA sequences in matched serum, peripheral blood mononuclear cells (PBMC) and liver samples in 10 patients with GBV-C/HGV infection, 8 of whom were coinfected with HCV was explored. Positive- and negative-strand GBV-C/HGV and HCV RNA were detected by strand-specific reverse-transcription polymerase chain reaction (RT-PCR), and virus titers were quantified by competitive PCRs. Positive-strand GBV-C/HGV RNA was detected in 7 of 10 PBMC samples of the patients with serum GBV-C/HGV RNA, but negative-strand GBV-C/HGV RNA was not found in these cells. Positive-strand GBV-C/HGV RNA was found in 9 liver samples, and 2 (22%) of them also had negative strand. In contrast, negative-strand HCV RNA was frequently found in PBMC and liver samples. A positive correlation between the titer of viral RNA in liver tissue and that in serum sample was demonstrated in HCV infection, but not in GBV-C/HGV infection. These findings suggest that liver and PBMC are not the major replication sites for GBV-C/HGV and that GBV-C/HGV is not a primary hepatotropic virus.

Adult↗
PubMed1999

When is fasting really fasting? The influence of time of day, interval after a meal, and maternal body mass on maternal glycemia in gestational diabetes.

OBJECTIVE: The object of the study was to determine whether time of day, interval after a standard meal, and maternal body mass influence plasma glucose concentrations in women with gestational diabetes mellitus. STUDY DESIGN: Identical mixed meals were administered on 2 separate occasions 1 week apart to 30 women with dietarily treated gestational diabetes and pregnancies between 28 and 38 weeks' gestation. One meal was administered at 7 AM (morning meal) and the other was administered at 9 PM (evening meal), each after a fast of >/=5 hours. The order of the meals (morning first versus evening first) was assigned randomly. Sixteen of the women had a body mass index >/=27 kg/m(2) (overweight) and 14 women had a body mass index <27 kg/m(2) (lean). Venous plasma concentrations of glucose, insulin, free fatty acids, beta-hydroxybutyrate, and bound and free cortisol were measured hourly for 9 hours after each of the test meals. RESULTS: When all women were considered together glucose concentrations after the morning meal were significantly greater at 1 hour, were not different at 2 hours, and were significantly lower from 3 through 9 hours postprandially than those at corresponding times after the evening meal. Plasma beta-hydroxybutyrate and free fatty acid concentrations were higher between 5 and 9 hours after the morning meal than at the same times after the evening meal. Total and free cortisol levels were higher for the first 7 hours after the morning feeding, reflecting known diurnal variation in cortisol concentrations. Overweight patients' glucose values were significantly greater than those of lean subjects during the last 4 hours of the overnight fast. CONCLUSIONS: Among women with dietarily treated gestational diabetes the glucose concentrations were significantly higher from 3 to 9 hours after an evening meal, whereas suppression of free fatty acids and beta-hydroxybutyrate was less sustained after a morning feeding. The mechanisms underlying these differences remain to be determined but may involve diurnal influences of counterregulatory hormones. The relationships between measurements of maternal glycemia and maternal and perinatal outcomes in pregnancies complicated by gestational diabetes may be clarified by establishing a uniform duration of a fast and by developing meal-specific preprandial and postprandial maternal glucose targets for these patients.

3-Hydroxybutyric Acid↗
PubMed1999

The association of cardiovascular risk factor clustering related to insulin resistance syndrome (Syndrome X) between young parents and their offspring: the Bogalusa Heart Study.

Cardiovascular risk factor clustering related to insulin resistance syndrome (Syndrome X) was examined in a community-based sample of 599 genetically unrelated school-aged children (5-17 years) and their parents. Risk factors used as components of Syndrome X included hyperinsulinemia, obesity, dyslipidemia and high blood pressure defined by values above the age-, sex- and race-specific 75th percentiles of fasting insulin, body mass index, triglycerides/high-density lipoprotein cholesterol ratio and mean arterial pressure, respectively. Based on observed to expected ratio there was an excess of parents (father and/or mother) and their offspring with clusters of three or four disorders (P < 0.05-0.001). In contrast, the number of parents and offspring with two disorders was significantly lower than expected by chance alone (P < 0.05-0.01). Based on paternal, maternal, and parental Syndrome X, the odds ratios (95% confidence interval) for offspring having the same cluster were 7.2 (1.9-27.2), 8.6 (3.1-23.6) and 7.9 (3.5-18.1), respectively. In terms of individual risk factors of parents used as predictors, adverse levels of their insulin and BMI significantly increased the risk of offspring having Syndrome X (P < 0.01-0.001), whereas the effect of parental insulin was considerably reduced after parental BMI was adjusted for. In contrast, parental dyslipidemia and high blood pressure were not associated with the occurrence of Syndrome X in their offspring. These results confirm the familial nature of Syndrome X and suggest that conditions of obesity and the attendant hyperinsulinemia in parents may underlie this familial association.

Adolescent↗
PubMed1999

Force spectroscopy between acetylcholinesterase molecule and its natural substrate to study the effects of inhibitors and reactivators on enzyme activity.

The force spectrum (FS) between acetylcholinesterase (AChE) molecule and its natural substrates acetylcholine (ACh) and the influences of AChE inhibitors and reactivators have been investigated with atomic force microscopy (AFM) at single molecule level in real-time. AChE and ACh were covalently immobilized onto the surfaces of gold-plated mica and Si3N4 tip of the atomic force microscope respectively. First, AChE was imaged in image mode of AFM and one of AChE molecules was selected as the center of the scanning. Then scanning mode was changed into force scanning mode and FS was recorded in a frequency of 5 x s(-1). Solutions of drugs or toxicants can be injected from the fluid-in tube of the fluid cell at any desired time. The FS between ideally immobilized normal AChE, Inhibited AChE or aged AChE and ACh each had their own shape features. The influences of drugs or toxicants on these features could be observed in real-time on the screen of the computer. These results demonstrated that AFM force spectroscopy could be used as a new method to study the effects of drugs and toxicants on the activity of the enzyme in pharmacology and toxicology.

Acetylcholine↗
PubMed1999

Behavioral analysis of PTZ-kindled rats after acute and chronic ethanol treatments.

The present study was designed to examine the response of PTZ-kindled and saline-injected animals to both acute and chronic ethanol treatment. Acute injection of ethanol (3.0 g/kg; IP) resulted in a rapid onset of loss of righting reflex (LORR) in both PTZ-kindled and saline-injected animals. However, the PTZ-kindled animals recovered from LORR significantly more quickly than control animals. Using a tilt-plane test as a measure of motor incoordination, the PTZ-kindled animals had significantly less motor incoordination compared to controls. Blood alcohol levels (BAL) were not significantly different between the groups. We also compared the degree of tolerance and dependence in chronic ethanol-treated, PTZ-kindled, and control animals. PTZ-kindled, saline-injected and naive control animals were chronically treated with ethanol vapor. The PTZ-kindled group tolerated high vapor concentrations (in terms of food consumed/rat) and, at the end of the treatment, displayed intoxication characteristics different from those of the control groups despite having similar blood alcohol levels. The PTZ-kindled group also displayed withdrawal behavior that was similar to a group of ethanol-treated animals that had experienced a prior cycle of dependency and withdrawal. These data show many intriguing similarities between animals that are PTZ-kindled and chronically treated with ethanol and suggest the use of PTZ-kindled animals as a model for alcohol withdrawal kindling.

Animals↗
PubMed1999

Critical care transport: outcome evaluation after interfacility transfer and hospitalization.

STUDY OBJECTIVE: To test the hypothesis that interfacility transfer is not associated with increased mortality, duration of stay, or readmission within 7 days. METHODS: We matched 3,298 patients who were hospitalized for chest pain or related complaints in Kaiser Permanente medical centers after transfer from the emergency department of a nonplan hospital (transported patients) with 3,298 patients of the same gender and age (+/-5 years) and with the same principal diagnosis who were hospitalized within 6 months without transfer in the same Kaiser Permanente medical center (directly admitted patients). Patients were compared in terms of outcome measures: in-hospital deaths, continued care in another facility, readmission within 7 days, in-patient length of stay (LOS), and LOS in special care units. RESULTS: The adjusted odds ratios for in-hospital mortality and readmission within 7 days were 1.0 (95% confidence interval,.8 to 1.4) and.9 (95% confidence interval,.7 to 1.2), respectively. The adjusted mean difference in LOS was -.1 days (95% confidence interval, -.2 to.1). Transported and directly admitted cardiac patients were also compared for all examined outcome measures at each of 10 medical centers. At a few medical centers, we observed significant difference in LOS, special care LOS, and continued care in another facility. However, all these differences were small, and most were probably random errors. CONCLUSION: Conservative patient selection criteria, pretransfer stabilization, and the use of appropriate equipment and medical personnel have resulted in the interfacility transfer program's achieving its goal of transferring high-risk patients without adverse impact on clinical outcomes or resource use.

Aged↗
PubMed1999

Engineering of improved microbes and enzymes for bioremediation.

Bioremediation with microorganisms is an attractive alternative to conventional techniques, such as incineration and chemical treatment, for disposing of pollutants. Recent progress in molecular biology, microbiology, and genetics is providing the driving force towards engineering improved microbes and enzymes for bioremediation. A number of genetic engineering approaches have been developed in the past several years that have proven useful in introducing/evolving the desired properties for different biodegradative pathways or enzymes. The initial excitement generated in this area should continue to pave the way for rational or irrational design of microbes or enzymes with novel remedial properties.

Amino Acid Sequence↗
PubMed1999

Manipulation of TGF-beta to control autoimmune and chronic inflammatory diseases.

Defining the mechanisms whereby transforming growth factor-beta (TGF-beta) controls physiologic inflammation and the immune response and how it contributes to pathology when it is dysregulated is critical to our ability to manipulate the levels and activity of this potent cytokine for therapeutic benefit. In keeping with its dichotomous nature, recent evidence suggests that overproduction and/or activation contribute to persistent inflammation and that antagonists of TGF-beta delivered locally can break the cycle of leukocyte recruitment and fibrotic sequelae. On the other hand, systemic routing of TGF-beta can also inhibit inflammatory pathogenesis by multiple mechanisms as exemplified by systemic injections of the protein and by recent gene transfer studies. In addition, enhanced levels of circulating endogenous TGF-beta appear to be an instrument of suppression during the development of oral tolerance, cyclosporin treatment, and following administration of retinoic acid. Although treatment of autoimmune and chronic inflammatory diseases is an important goal, the multiplicity of actions of TGF-beta and the nearly ubiquitous expression of TGF-beta and its receptors dictate a cautious approach to the use of this powerful cytokine as a therapeutic agent.

Animals↗
PubMed1999

Organophosphorus hydrolase-based assay for organophosphate pesticides

We report a rapid and versatile organophosphorus hydrolase (OPH)-based method for measurement of organophosphates. This assay is based on a substrate-dependent change in pH at the local vicinity of the enzyme. The pH change is monitored using fluorescein isothiocyanate (FITC), which is covalently immobilized to the enzyme. This method employs the use of poly(methyl methacrylate) beads to which the FITC-labeled enzyme is adsorbed. Analytes were then measured using a microbead fluorescence analyzer. The dynamic concentration range for the assay extends from 25 to 400 &mgr;M for paraoxon with a detection limit of 8 &mgr;M. Organophosphorus insecticides measured using this technique included ethylparathion, methylparathion, dursban, fensulfothion, crotoxyphos, diazinon, mevinphos, dichlorvos, and coumaphos. This technique was used to measure coumaphos in biodegradation samples of cattle dip wastes and showed a high correlation (r2 = 0.998) to an HPLC method.

Journal Article↗