Search PubMed⌕ Search

Biomedical subjects

C Wang

Publications and source records attributed to C Wang.

At least 343 records · Page 19Linked to original sources
PubMed2000

In vitro activity of meropenem and four other antibiotics against 554 clinical strains obtained from Beijing in 1999.

In 1999, a surveillance study was initiated in a hospital in Beijing to monitor the potency and spectrum of five extended-spectrum beta-lactam antimicrobial agents (meropenem, imipenem, cefepime, ceftazidime, and cefoperazone/sulbactam) tested against 554 strains of bacteria. Five groups of organisms were tested by the E-test method, with results validated by concurrent quality control strain analysis. Results were tabulated, and 100% of quality assurance tests (16/16 tests) were within ranges recommended by the National Committee for Clinical Laboratory Standards. Of the five beta-lactam drugs tested, meropenem and imipenem were the most active against all isolates tested. Overall, the rank order of activity of the five agents was: meropenem (94.6% susceptible) > imipenem (90.1%) > cefepime (77.6%), cefoperazone/sulbactam (77.5%), ceftazidime (76.6%). Ninety-five percent of Enterobacter were to meropenem, while 82% were susceptible to imipenem. Meropenem was more active than imipenem against Pseudomonas aeruginosa. The minimum inhibitory concentration (MIC) of meropenem was eightfold lower than that of imipenem. Meropenem had excellent activity against Haemophilus influenzae, Streptococcus pneumoniae, and oxacillin-susceptible staphylococci.

Anti-Bacterial Agents↗
PubMed2000

Explaining two-lane highway crash rates using land use and hourly exposure.

This paper describes the estimation of Poisson regression models for predicting both single and multi-vehicle highway crash rates as a function of traffic density and land use, as well as ambient light conditions and time of day. The study focuses on seventeen rural, two-lane highway segments, each one-half mile in length with varying land use patterns and where actual hourly exposure values are available in the form of observed traffic counts. Land-use effects are represented by the number of driveways of various types on each segment. Hourly exposure is represented for single-vehicle crashes as the total vehicle miles traveled and volume/capacity ratio; for multi-vehicle crashes it is the product of the hourly volumes on the main highway and the roads intersecting it along the study segment. For single-vehicle crashes, the following variables were found to be significant, with a positive or negative effect as noted: daytime (06:00-19:00 h, negative effect), the natural log of the segment volume/capacity ratio (negative), percent of the segment with no passing zones (positive), shoulder width (positive), number of intersections (negative), and driveways (mixed effects by type). Good multi-vehicle crash prediction models had quite different variables: daylight conditions from 10:00-15:00 and 15:00-19:00 h (positive), number of intersections (negative), and driveways (positive for all types). The results show that traffic intensity explains differences in crash rates even when controlling for time of day and light conditions, and that these effects are quite different for single and multi-vehicle crashes. Suggestions for future research are also given.

Accidents, Traffic↗
PubMed2000

Surgical treatment of primary midbrain gliomas.

BACKGROUND: The treatment of brainstem gliomas remains controversial. This article focuses on surgical results. METHODS: The authors retrospectively analyzed 35 patients with primary midbrain gliomas who were treated at Beijing Neurosurgical Institute from 1986 to 1997. The diagnosis was verified by histological examination. RESULT: The incidence of midbrain glioma was 10.3% (35/340) in our patients with brain stem tumors. The 35 gliomas were classified into three therapeutic groups by their locations: 7 were located in the tectal region, 8 in the aqueductal region, and 20 in the tegmental region. All of the patients underwent microsurgical treatment based on a minimally invasive approach. The operation took the form of total resection in 19 cases, subtotal resection in 12, and partial resection in 4. The operative mortality was 0. With a mean follow-up of 28 months (range, 6-48 months), 65.7% (23/35) of patients could live independently. CONCLUSION: The volume and location of midbrain tumors were highly correlated with outcome. The resection of as much tumor as possible was optimal for the treatment of midbrain gliomas and radiotherapy after operation was beneficial to patients.

Adolescent↗
PubMed2000

Psychological adjustment to familial genetic risk assessment: differences in two longitudinal samples.

Heritable cancer risk assessment is an increasingly common method of deriving valuable information relevant to deciding on appropriate screening regimens and preventive treatments. Assessments of heritable risk typically include familial-genetic evaluation, where analyses relate family pedigree to cancer risk, and DNA testing, where analyses indicate genetic mutations associated with cancer risk (e.g., BRCA1/BRCA2 mutations) or their absence. In this paper we report on the psychological responses of women given familial-genetic evaluations for ovarian cancer risk. The baseline and 6 to 12 follow-up assessments of an initial clinic-attending cohort of 65 women are compared with the baseline and 9 to 12 follow-up assessments of a second clinic-attending cohort of 60 women. Sizeable differences were found in the prevalence of clinically significant depression in these two physician or self-referred populations, as assessed by the Center for Epidemiological Studies Depression scale and in the mean scores. Hypotheses accounting for these differences are discussed.

Adaptation, Psychological↗
PubMed2000

Inhibition of natural killer cell-mediated cytotoxicity by Kaposi's sarcoma-associated herpesvirus K5 protein.

Kaposi's sarcoma-associated herpesvirus (KSHV) K3 and K5 proteins dramatically downregulate MHC class I molecules. However, although MHC class I downregulation may protect KSHV-infected cells from cytotoxic T lymphocyte recognition, these cells become potential targets for natural killer (NK) cell-mediated lysis. We now show that K5 also downregulates ICAM-1 and B7-2, which are ligands for NK cell-mediated cytotoxicity receptors. As a consequence, K5 expression drastically inhibits NK cell-mediated cytotoxicity. Conversely, de novo expression of B7-2 and ICAM-1 resensitizes the K5-expressing cells to NK cell-mediated cytotoxicity. This is a novel viral immune evasion strategy where KSHV K5 achieves immune avoidance by downregulation of cellular ligands for NK cell-mediated cytotoxicity receptors.

Antigens, CD↗
PubMed2000

A computer-aided design mammography screening system for detection and classification of microcalcifications.

This paper presents a prototype of a computer-aided design (CAD) diagnostic system for mammography screening to automatically detect and classify microcalcifications (MCCs) in mammograms. It comprises four modules. The first module, called the Mammogram Preprocessing Module, inputs and digitizes mammograms into 8-bit images of size 2048x2048, extracts the breast region from the background, enhances the extracted breast and stores the processed mammograms in a data base. Since only clustered MCCs are of interest in providing a sign of breast cancer, the second module, called the MCCs Finder Module, finds and locates suspicious areas of clustered MCCs, called regions of interest (ROIs). The third module, called the MCCs Detection Module, is a real time computer automated MCCs detection system that takes as inputs the ROIs provided by the MCCs Finder Module. It uses two different window sizes to automatically extract the microcalcifications from the ROIs. It begins with a large window of size 64x64 to quickly screen mammograms to find large calcified areas, this is followed by a smaller window of size 8x8 to extract tiny, isolated microcalcifications. Finally, the fourth module, called the MCCs Classification Module, classifies the detected clustered microcalcifications into five categories according to BI-RADS (Breast Imaging Reporting and Data System) format recommended by the American College of Radiology. One advantage of the designed system is that each module is a separate component that can be individually upgraded to improve the whole system. Despite that it is still is a prototype system a preliminary clinical evaluation at TaiChung Veterans General Hospital (TCVGH) has shown that the system is very flexible and can be integrated with the existing Picture Archiving and Communications System (PACS) currently implemented in the Department of Radiology at TCVGH.

Algorithms↗
PubMed2000

Endogenous parathyroid hormone-related peptide enhances proliferation and inhibits differentiation in the osteoblast-like cell line ROS 17/2.8.

To investigate potential effects of endogenous parathyroid hormone-related peptide (PTHrP) on osteoblast function, ROS 17/2.8 cells were transfected with full-length PTHrP cDNA in a sense or antisense orientation to alter PTHrP production. Compared with vector-transfected control cells, PTHrP-overproducing (sense-transfected) cells showed increased DNA synthesis ([(3)H]-thymidine incorporation) and increased growth (cell number). The extent of apoptosis was compared for the different clones using the terminal deoxynucleotide-mediated dUTP nick-end-labeling assay (TUNEL) and Hoechst staining. No differences in percentages of apoptotic cells were found under basal culture conditions or after 3 days of serum deprivation, which, itself, markedly increased numbers of apoptotic cells. The effect of PTHrP on osteoblast differentiation was assessed by examining two protein markers of differentiation, alkaline phosphatase, and bone morphogenetic protein (BMP)-2. Alkaline phosphatase activity was decreased in sense-transfected cells and increased in antisense-transfected cells, compared with cells transfected with empty vector. PTHrP-overproducing cells also showed decreased numbers of BMP-2-positive cells, whereas antisense-transfected cells showed no difference compared with vector control. The results indicate that: (a) endogenously produced PTHrP can increase growth of these osteoblastic cells by stimulating proliferation while not affecting apoptosis; and (b) the increased cell proliferation produced by PTHrP was accompanied by a reduction in activity or amount of two proteins normally expressed by differentiated osteoblasts.

Alkaline Phosphatase↗
PubMed2000

Lung compartmentalization of inflammatory cells in sepsis.

Lung injury commonly occurs in the setting of systemic inflammatory response syndrome occurring during bacterial sepsis. There has been little work quantifying different leukocytes within the different compartments of the lung and their association with overt lung injury in sepsis. We examined the pathogenesis of lung injury after cecal ligation and puncture (CLP), a clinically relevant model of sepsis. To assess the sequestration and migration of leukocytes, leukocyte differentials were obtained for the lung vascular compartment and the bronchoalveolar airspace. At 24 h post CLP, there were signs of edema in the lung, while at 48 h after CLP, there were clear indications of alveolar wall thickening with increased cellularity and diffuse alveolar hemorrhage. The number of lymphocytes in the pulmonary vascular compartment dropped by 50% and doubled in the (bronchoalveolar lavage) BAL, 24 h after CLP compared to sham controls suggesting that there was transendothelial migration of lymphocytes. At 48 h after CLP, lymphocyte numbers in the vasculature was similar to controls but BAL lymphocyte numbers were still raised. The number of pulmonary intravascular neutrophils were similar to controls at 24 h post CLP but were greatly elevated 48 h after CLP. The increase in neutrophils was partly due to a substantial increase in the percentage of immature band cells, indicating recruitment of neutrophils from the bone marrow. There were very few neutrophils in the BAL of sham controls and CLP rats. Perfusate monocyte/macrophages were significantly increased 48 h after CLP and a similar increase in macrophages was observed in the BAL. These results strongly suggest a role for lymphocytes and macrophages in the development of overt lung injury as the migration of these cells corresponds to that of the appearance of lung injury 48 h after CLP. Importantly our data also demonstrates the compartmentalization and migration of different inflammatory cell-types during the development of sepsis.

Animals↗
PubMed2000

GroEL and protein disulfide isomerase each binds with folding intermediates of D-glyceraldehyde-3-phosphate dehydrogenase released from complexes formed with the other.

Simultaneous presence of two chaperones, GroEL and protein disulfide isomerase (PDI), assists the reactivation of denatured D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in an additive way. Delayed addition of chaperones to the refolding solution after dilution of denatured GAPDH indicates an interaction with intermediates formed mainly in the first 5 min for PDI and formed within a longer time period for GroEL-ATP. The above indicate that the two chaperones interact with different folding intermediates of GAPDH. After delayed addition of one chaperone to the refolding mixture containing the other at 4 degrees C, GroEL binds with all GAPDH intermediates dissociated from PDI, and PDI interacts with the intermediates released from GroEL during the first 10-20 min. It is suggested that the GAPDH folding intermediates released from the chaperone-bound complex are still partially folded so as to be rebound by the other chaperone. The above results clearly support the network model of GroEL and PDI.

Adenosine Triphosphate↗
PubMed2000

Evidence that specific T lymphocytes may participate in the elimination of chronic myelogenous leukemia.

Although the immune system has long been implicated in the control of cancer, evidence for specific and efficacious immune responses in human cancer has been lacking. In the case of chronic myelogenous leukemia (CML), either allogeneic bone marrow transplant (BMT) or interferon-alpha2b (IFN-alpha2b) therapy can result in complete remission, but the mechanism for prolonged disease control is unknown and may involve immune anti-leukemic responses. We previously demonstrated that PR1, a peptide derived from proteinase 3, is a potential target for CML-specific T cells. Here we studied 38 CML patients treated with allogeneic BMT, IFN- alpha2b or chemotherapy to look for PR1-specific T cells using PR1/HLA-A*0201 tetrameric complexes. There was a strong correlation between the presence of PR1-specific T cells and clinical responses after IFN-alpha and allogeneic BMT. This provides for the first time direct evidence of a role for T-cell immunity in clearing malignant cells.

Blood Circulation↗
PubMed2000

Inhibition of cell proliferation in HCC-9204 hepatoma cells by a c-myc specific ribozyme.

A ribozyme (RZ) gene targeting c-myc mRNA was synthesized and cloned. Cleavage reaction showed that cleavage of the RZ was efficient and specific. The RZ gene-containing retrovirus vector pDOR-RZ was transfected into HCC-9204 hepatoma cells, which constitutively express high levels of c-myc using Lipofectamine. Positively transfected cells were selected using G418. In situ hybridization showed that both pDOR-RZ and pDOR vectors had been integrated into the chromosome of HCC-9204 cells. Dot blot hybridization indicated that expression of the RZ was only evident in pDOR-RZ-transfected HCC-9204 cells. Avidin-biotin complex enzyme-linked immunosorbent assay showed that c-myc expression was down-regulated. Chromatin aggregation into compact masses, cytoplasmic vacuole degeneration, and blurring of cytoplasm structure were observed by transmission electron microscopy in HCC-9204-RZ cells. These results suggest that the use of a c-myc mRNA cleaving enzyme could be most effective in tumor cells that are highly proliferative and constitutively express high levels of c-myc.

Carcinoma, Hepatocellular↗
PubMed2000

Carbon disulfide at a Chinese viscose factory external and internal exposure assessment.

This article presents the results of carbon disulfide exposure measurements in a Chinese viscose rayon factory. The objectives of the study were to identify the external exposure levels at a large factory and to investigate the 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations in the urine of the subjects who were exposed to carbon disulfide in the working place atmosphere. The metabolism of carbon disulfide in the exposed subjects was also studied in order to demonstrate the best points in time for the internal exposure sampling. The measurement of the amount of personal exposure to carbon disulfide in the air of the workplace was performed by GC-FPD; the presence of TTCA in the workers urine was analyzed by use of a modified HPLC method. The kinetics of TTCA excretion was studied by analyses at different time-points both during and after exposure to carbon disulfide in the subjects. A total of 155 personal samples were obtained. The carbon disulfide concentration in the staple viscose hall was 13.72 +/- 1.12 mg m-3 in terms of the geometric mean +/- geometric standard deviation, and was 20.05 +/- 1.33 mg m-3 in the filament spinning hall. The TTCA values in the subjects who worked in the staple spinning hall were 1.18 +/- 0.43 mg g-1 creatinine and 1.07 +/- 0.38 mg g-1 creatinine for subjects working in the filament spinning hall. The best time for TTCA sampling is at the end of the working shift, the TTCA excretion was stable for a period of 4-12 h after exposure of the subjects to the carbon disulfide. It might be that the Chinese have different anthropometric characteristics; a sampling bias may therefore appear among different races.

Adult↗
PubMed2000

Comparison of the effects of inhalational anaesthetic agents on sympathetic activity in rabbits.

The effects of inhalational anaesthetic agents on renal sympathetic nerve activity (RSNA) were compared in anaesthetized rabbits. Concentrations of 6% desflurane, 1.2% isoflurane, and 2.4% enflurane increased mean RSNA up to 32, 36 and 44% while higher concentrations, of 12, 2.4 and 3.2% depressed it by 42, 83 and 5%, respectively. For halothane RSNA was unchanged up to 0.8% and decreased by 36% at 1.6% concentration. Nitrous oxide increased RSNA up to 28% at 50% concentration. Maximum reductions in mean arterial pressure (MAP) were 60% for both 2.4% isoflurane and 3.2% enflurane, 50% for 12% desflurane and 1.6% halothane, while 70% nitrous oxide increased MAP by 22%. In conclusion, unlike the entirely depressive effects of halothane, the effects of desflurane, isoflurane and enflurane were biphasic involving excitation at lower concentrations and depression of RSNA and a reduction in MAP at higher concentrations. Nitrous oxide caused increases in both RSNA and MAP.

Anesthetics, Inhalation↗
PubMed2000

A biodialysis system for liver support tested in a porcine hepatic failure model.

BACKGROUND: A practical liver support system for patients in fulminant hepatic failure (FHF) remains a needed therapeutic modality. A new method of bioartificial liver support, the liver biodialysis system (LBDS), is described. METHODS: Porcine hepatocytes, removed from direct contact with the treated subject's circulation, are in culture in a bioreactor which is combined in a dialysis circuit for patient treatment. The LBDS was tested in a porcine ischaemic hepatic failure model. RESULTS: The viable hepatocyte content of the bioreactor was 2.49 +/- 0.72 x 10(10). Cells remained viable in culture throughout the experiments (30 +/- 3 h) without evidence of immunological damage. A decrease in the degree of accumulation in the blood of ammonia (P < 0.02) and of 14 amino acids (P < 0.001) was achieved by the LBDS. Cerebral perfusion pressure was maintained at significantly higher levels in LBDS-treated animals (P < 0.05). CONCLUSIONS: In the LBDS, hepatocytes in large numbers and satisfactory culture conditions in a bioreactor have sustained viability and function. When combined in a dialysis circuit for the treatment of FHF pigs, immune reactions between the blood and hepatocytes were prevented and beneficial metabolic effects were observed.

Amino Acids↗
PubMed2000

Neurotensin stimulates Cl(-) secretion in human colonic mucosa In vitro: role of adenosine.

BACKGROUND & AIMS: Previous studies indicated that the peptide neurotensin (NT) stimulates Cl(-) secretion in animal small intestinal mucosa in vitro. In this study, we investigated whether NT causes Cl(-) secretion in human colonic mucosa and examined the mechanism of this response. METHODS: Human mucosal preparations mounted in Ussing chambers were exposed to NT. Drugs for pharmacologic characterization of NT-induced responses were applied 30 minutes before NT. RESULTS: Serosal, but not luminal, administration of NT (10(-8) to 10(-6) mol/L) induced a rapid, monophasic, concentration- and chloride-dependent, bumetanide-sensitive short-circuit current (Isc) increase that was inhibited by the specific nonpeptide NT receptor antagonists SR 48692 and SR 142948A, the neuronal blocker tetrodotoxin, and the prostaglandin synthesis inhibitor indomethacin. The mast cell stabilizer lodoxamide and the histamine 1 and 2 receptor antagonists pyrilamine and ranitidine, respectively, did not significantly alter NT-induced Isc increase. In contrast, the adenosine receptor 1 and 2 antagonists inhibited this secretory response, whereas the adenosine uptake inhibitors S-(4-nitrobenzyl)-6-thioguanosine and S-(4-nitrobenzyl)-6-thioinosine and the adenosine deaminase inhibitor deoxycoformycin potentiated NT-induced Isc increase. Serosal adenosine induced a rapid, monophasic, concentration- and chloride-dependent, bumetanide-sensitive Isc increase. CONCLUSIONS: NT stimulates chloride secretion in human colon by a pathway(s) involving mucosal nerves, adenosine, and prostaglandins.

Adamantane↗