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Biomedical subjects

C L Chen

Publications and source records attributed to C L Chen.

At least 235 records · Page 13Linked to original sources

Case report: paucity of interlobular bile ducts in Chinese children.

Sixteen Chinese children with cholestasis since early infancy were diagnosed to have paucity of interlobular bile ducts (PILBD) or its equivalent. Twelve children belonged to the syndromic group of PILBD and four children belonged to the non-syndromic group. A definite histological diagnosis of bile duct paucity was established in only two children (aged 4 and 9 months) during the first percutaneous needle biopsy. In the remaining 14 children a varying degree of bile duct destruction was evident in the follow up percutaneous or wedge liver biopsies. The evolving changes were characterized by inflammatory infiltration near or at the ductal wall, the presence of dysmorphic ductules, the degeneration of ductal epithelia and a progressive decrease of interlobular bile ducts. Of 10 children who underwent laparotomy for definite diagnosis, kasai operation was performed in two of them. In the syndromic PILBD group, all children, including two paired siblings, had at least three of five major clinical features. Hypoplasia of the extrahepatic biliary tree was found in five children and atresia of the extrahepatic bile duct was found in one. Three of six children studied were shown, by polymerase chain reaction, to have cytomegalovirus infection in the liver. This study demonstrates that bile duct paucity is a result of progressive bile duct destruction. A definitive diagnosis is difficult to make in early infancy. Thus, the careful evaluation of extrahepatic features in cholestatic children and follow-up liver biopsies are indicated. Although the pathogenetic mechanism of PILBD is unknown, bile duct destruction is the common pathway leading to paucity of bile ducts irrespective of syndromic or non-syndromic types.

Bile Ducts↗

Differential expression of EBER1 in nontumor nasopharyngeal biopsies and nontumor component of nasopharyngeal carcinoma.

The close association of Epstein-Barr virus (EBV) and nasopharyngeal carcinoma (NPC) is well documented and the expression of EBV-related latent genes has been shown in NPC. Nevertheless, the status of EBV infection in the nontumor epithelial and lymphoid cells is not known. In this study, we detected EBV in the nontumor component of NPC and nontumor nasopharyngeal biopsies by in situ hybridization using digoxigenin-labeled antisense EBER1 oligoprobe in 346 nasopharyngeal biopsies. Latent membrane protein (LMP) and ZEBRA were detected by immunohistochemistry in cases containing EBER1-positive cells. The EBV-positive epithelial and lymphoid cells were identified by immunostains for cytokeratin and lymphoid phenotypes. In the nontumor nasopharyngeal biopsies, 21 (11.7%) of 179 cases had EBV-harboring lymphocytes in the lymphoid tissue, while the overlying mucosa was all negative. LMP was demonstrated in lymphoid cells of 14 (66.7%) of these 21 samples. These EBV-positive lymphocytes were B lymphocytes by combined phenotype study. EBER1-containing metaplastic squamous cells were demonstrated in the overlying mucosa close to the tumor tissue in 14 (8.4%) of 167 NPC samples. In contrast, the respiratory epithelial cells in these cases were all negative. Two (1.2%) of these cases had EBV-positive lymphocytes in the lymphoid stroma. Four of the 346 cases had ZEBRA-positive cells. This study demonstrated that latent infection and, occasionally, active replication of EBV were present in stromal B lymphocytes in nasopharyngeal tissue with and without NPC. EBER1 was found only in the metaplastic squamous cells in the mucosa of nasopharyngeal tissues with NPC, but not in those without NPC.

Adolescent↗

Analysis of the rat clusterin gene promoter and cyclic AMP-regulated mRNA stability in testicular cells.

Clusterin, also known as SGP-2 or TRPM-2, is expressed in the male reproductive tissues at different levels. The genomic structure of the rat clusterin gene was recently reported by our laboratory and others. In this study, we have determined the promoter responsible for the basal expression of the rat clusterin gene in testicular cells by analyzing the transient expression of the bacterial chloramphenicol acetyl transferase (CAT) reporter gene in MA-10 cells driven by different segments of the 5'-flanking region and the first intron of the clusterin gene. The region required for maximal basal expression was identified at -266 to +54. Addition of DNA fragments of the rat clusterin gene from -1298 to -266 bp, or from +54 to +1153 to (-266/+54)CAT resulted in a 87% decrease in CAT activity, suggesting the presence of inhibitory DNA elements in both the 5'-flanking region and the first intron. When DNA fragment in the first intron, +1153 to +2874, was included, CAT activity in the (-266/+2874)CAT construct increased to 70% of the clusterin promoter (-266/+54)CAT, indicating that stimulatory DNA elements may be present in this region of the first intron. Treatment of MA-10 cells with cyclic AMP (cAMP) neither decreased CAT activity driven by any of the clusterin/CAT chimeric plasmids examined in transient transfection studies, nor reduced the synthesis of nuclear clusterin RNA in nuclear run-on assays, indicating that the reduction of clusterin mRNA levels by cAMP previously reported in our laboratory is not exerted at the transcriptional level. Furthermore, addition of transcriptional or translational inhibitors (actinomycin D and cycloheximide respectively) abolished the cAMP effect observed in MA-10 cells. In summary, we have demonstrated that the basal transcription of the rat clusterin gene in testicular cells is under the control of both positive and negative regulatory sequences at the 5'-flanking region as well as in the first intron. The reduction of clusterin mRNA after exposure of MA-10 cells to cAMP is not due to a decrease in its transcriptional activity, but rather to an increase in the degradation of this mRNA through synthesis of a destabilizing protein(s) and its mRNA.

Animals↗

Use of enzyme-linked immunosorbent assay and radioimmunoassay to determine serum and urine dexamethasone concentrations in thoroughbreds after intravenous administration of the steroid.

OBJECTIVE: To develop a simple and sensitive ELISA for detection of dexamethasone in horse serum and urine. SAMPLE POPULATION: Blood and urine samples from 3 thoroughbred mares. PROCEDURE: A dexamethasone oxime was prepared and conjugated to hemocyanin, bovine serum albumin and to horseradish peroxidase. One- and two-step double-antibody ELISA methods, as well as a radioimmunoassay method, were performed. The one-step ELISA was used to test urine from 3 Thoroughbred mares injected with 5 mg of dexamethasone, IV. RESULTS: The ELISA could detect dexamethasone in the range of 0.01 to 50 ng/ml, with intra- and interassay variations of 8.92 and 9.42%, respectively. Serum dexamethasone concentration reached a peak of 20 to 35 ng/ml 15 minutes after steroid administration and decreased to 1 ng/ml in 2.5 hours. Urine dexamethasone concentration 18 to 50 ng/ml 1 to 2 hours after drug administration and decreased to 1 ng/ml at 10 hours. CONCLUSION: The developed assay is sensitive as well as simple for detecting dexamethasone in horse serum and urine, and is comparable to radioimmunoassay. CLINICAL RELEVANCE: This method can be useful for screening samples from racehorses, because it is sensitive and does not require sample preparation or sophisticated equipment.

Animals↗