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Biomedical subjects

C L Chen

Publications and source records attributed to C L Chen.

At least 289 records · Page 16Linked to original sources
PubMed1994

Partial liver transplantation from a living donor: experimental research and clinical experience.

Partial liver transplantation (PLTR) was studied experimentally, using 60 monkeys (20 recipients, 20 donors, 20 blood donors). The left lobe of the donors was transplanted orthotopically, using a veno-venous bypass catheter that was inserted in the portal vein and the other side passed through the hepatic portion of the inferior vena cava. The donor survival rate at 1 week was 70%. Seven recipients survived for more than 58 hours (58, 60, 64, 68, 72, 110, and 252 hours), and 13 died within 48 hours of surgery because of postoperative complications. Clinical living related liver transplantation (LRLT) was performed between June 1990 and March 1992 on six patients with biliary atresia and on one with liver cirrhosis and hepatocellular carcinoma. In all, the father's left lobe was transplanted orthotopically. Cyclosporine, azathioprine, and methyl prednisolone were administered. In addition, FK-506 was given to two patients in whom rejection was observed; one died 37 days after surgery because of acute rejection followed by systemic cytomegalovirus infection. The other six patients have survived for 8 to 29 months since transplantation. All six have been discharged from the hospital and are enjoying normal daily life. The postoperative course of all donors was uneventful. They were discharged 2 weeks after the operation and returned to their jobs in 2 months. The authors conclude that PLTR from a living donor is a promising therapeutic alternative to liver transplantation from a cadaver.

Adult↗
PubMed1994

Interaction of selenium and arsenic with metallothionein: effect of vitamin B12.

The effects of selenium and arsenic on metallothionein (MT) levels were determined in vitamin B12-supplemented and depleted rats. The binding of selenium and arsenic to MT in vitro and in vivo was also investigated. Rats fed a vitamin B12-deficient diet had significant (p < 0.05), higher levels of liver MT as compared to vitamin B12-supplemented rats. Rats fed 5-9 micrograms/g selenium as selenite or 50-150 micrograms/g arsenic as arsenite showed no significant increase of MT content in the liver. However, significant increases in MT levels in liver (p < 0.01) and kidney (p < 0.05) were seen when rats were injected with 1.5 mg selenium as selenite, and increase of liver MT levels (p < 0.05) was shown when injected with 5 mg arsenic as arsenite/kg body weight. In comparison to zinc, injection of selenium or arsenic caused only a slight elevation of liver MT levels. Liver cytosolic Sephadex G-75 patterns of rats injected with both zinc and arsenic gave separate peaks for arsenic and zinc which suggest that in vivo arsenic binding to MT may be insignificant. Spectrophotometric absorption changes at 255 nm with various levels of selenium or arsenic additions to an MT solution were used to show that selenite gave a maximum absorption increase at a 1:1 molar ratio, but maximum absorption change occurred with arsenite at a molar ratio of 7:1.

Animals↗
PubMed1994

Effects of heat stress on Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activities of broiler chickens vital organs.

Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activities of brain, heart, kidney, and small and large intestinal mucosa of broiler chickens exposed to heat stress (41 degrees C, 65% relative humidity for 6 h) and thermoneutral (25 degrees C, 65% relative humidity) conditions were determined. Brain and kidneys were found to have significantly higher Na+,K(+)-ATPase activities than those of heart and intestinal mucosa. Mg(2+)-activated ATPase and Na(+)-ATPase activities in the intestinal mucosa were higher than those of brain, kidneys, and heart under thermoneutral conditions. While there was a significant inhibition of total ATPase, Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activity of small and large intestinal mucosa of broiler chickens exposed to heat stress, the inhibitory effect was limited to total ATPase and Na+,K(+)-ATPase enzymes in kidneys. Heat stress produced a significant increase only in Mg(2+)-activated ATPase activity of the heart, without a remarkable change in all forms of ATPase activity in the brain. Heat stress significantly decreased the ratio of Na+,K(+)-ATPase to Mg(2+)-ATPase in the heart, kidneys, and small and large intestinal mucosa. The percentage of Na(+)-ATPase in Na+,K(+)-ATPase of brain, heart, and kidneys did not significantly change during heat stress, but the ratio in small and large intestinal mucosa increased significantly during heat stress. The severe disturbances in both serum electrolytes and acid-base balance observed in previous heat stress studies could partly be mediated by direct or indirect effects of heat stress on Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activities of kidneys, and small and large intestinal mucosa of broiler chickens.

Adenosine Triphosphatases↗
PubMed1994

Prediction of probability of pneumonectomy for lung cancer using Tc-99m MAA perfusion lung imaging.

Pulmonary perfusion scintigraphy with Tc-99m MAA was performed on 182 patients, on whom either pneumonectomy or lobectomy was performed, because of primary nonsmall-cell lung carcinoma. Among them, 76 underwent pneumonectomy, and 106 underwent lobectomy. The mean value of the perfusion fraction (PF) of the affected lung of the patients undergoing pneumonectomy was 32.3 +/- 13.6% (range, 4%-50%) and was less than that of the patients undergoing lobectomy, 43.5 +/- 4.5% (range, 27%-50%). The difference was statistically significant (t-test, t = 6.82; P < 0.001). Among the 28 patients whose PF of the affected lung was equal to or less than 30%, 26 underwent pneumonectomy and only 2 had a lobectomy. Among the 154 patients whose PF of the affected lung was more than 30%, 50 underwent pneumonectomy and 104 had a lobectomy. These result suggest that "30%" can be a cutoff value (Yates correction X(2) test, X2 = 33.09; P < 0.001).

Adult↗
PubMed1994

Gastric emptying of the intrathoracic stomach as oesophageal replacement for oesophageal carcinomas.

Thirty-eight patients who underwent oesophagogastrostomy for oesophageal carcinomas were included in this study. Nineteen cases had pyloroplasty or pyloromyotomy (group A) and the other 19 cases did not have drainage procedures of the intrathoracic stomach (group B). Radionuclide labelled solid meals were used to calculate the gastric emptying times (GET) of the intrathoracic stomachs. The GET of the patients was compared with the normal GET (88.7 +/- 14.2 min) from 25 normal volunteers. In the 38 patients, 18 (47%) demonstrated prolonged GET, 10 (26%) shortened GET, and the remaining 10 (26%) cases GET was within the normal range. Based on Fisher's tests, there was no significant difference (P > 0.05) in the incidence of prolonged and normal GET but significantly shorter (P < 0.05) GET between groups A and B. Our data suggest that the intrathoracic stomach appears to be of variable motility, different from the stomach located in the normal position. To preserve the better gastric emptying, a drainage procedure should be recommended for intrathoracic stomachs.

Adult↗
PubMed1994

Analysis of the gene cluster encoding carotenoid biosynthesis in Erwinia herbicola Eho13.

Erwinia herbicola is known to synthesize carotenoids and gives an orange-coloured phenotype. These carotenoids play a role in the protection of the cells from the damage caused by near-UV irradiation in nature. The genes encoding these carotenoids in E. herbicola Eho13 are clustered in a 7 kb DNA fragment. The complete sequence of this fragment has been determined. DNA sequence analysis revealed that the entire sequence contains at least five genes, which are transcribed in the same direction. These five genes are organized in the order crtE-crtX-crtY-crtI-crtB. A gene fusion study showed that two different regions in this 7 kb gene cluster contain promoter activity. Primer-extension analysis identified two transcription start sites, located 147 bp upstream from the first gene of the cluster, crtE, and within the last gene of the cluster, crtB. An RNA-PCR study suggested that the five crt genes were organized in an operon and were transcribed from the promoter upstream from crtE.

Alkyl and Aryl Transferases↗
PubMed1994

Skin elicitation threshold of ethylbutyl thiourea and mercaptobenzothiazole with relative leaching from sensitizing products.

We studied 3 contact sensitizers present in rubber products, ethylbutyl thiourea (EBT), 2-mercaptobenzothiazole (MBT) and 2,2-dithio-bis-benzothiazole (MBTS), to relate the amount of sensitizer eliciting allergic contact dermatitis to the quantity leaching from a product into various biological fluids: normal saline, human plasma and 3 synthetic sweat solutions of pH 5.5 to 7.5. To determine the amount of sensitizer remaining after leaching, Soxhlet extraction with acetonitrile was subsequently performed. High-performance liquid chromatography was used for chemical analysis. 12 MBT-sensitive patients were patch tested with serial dilutions of MBT and MBTS in petrolatum. A Latin Square design was used in statistical analysis of variance of the patch test results. Large amounts of thioureas leached from 2 rubber articles eliciting thiourea dermatitis, the literature suggesting that these would have been well above the elicitation threshold. Leaching of MBTS was relatively greater than MBT into most media, whereas MBT was a more potent elicitor than MBTS at equivalent concentrations. The lowest eliciting concentration of MBT in 1 subject was 0.01%. Such information should prove helpful to manufacturers in designed products that do not release allergens sufficiently to cause reactions in consumers.

Adolescent↗
PubMed1994

Regulation of RAG-2 protein expression in avian thymocytes.

The recombinase-activating genes, RAG-1 and RAG-2, have been shown to be necessary to initiate the process of V(D)J recombination during the ontogeny of lymphocytes. While much is known about the end products of this rearrangement process, little is known about the function or regulation of the components of the recombinase system. To this end, we have generated a monoclonal antibody to the chicken RAG-2 protein. Chicken thymocytes were found to express high levels of RAG-2, part of which is phosphorylated. Within thymocytes, RAG-2 is expressed primarily within the nucleus. RAG-2 protein levels are high in the CD4- CD8- and CD4+ CD8+ immature thymocytes but absent at the single-positive CD4+ CD8- or CD4- CD8+ stage of thymocyte development. Mitogenic stimulation of thymocytes with phorbol myristate acetate and ionomycin results in down-regulation of RAG-2 expression. Consistent with these data, in vivo levels of RAG-2 are markedly lower in proliferating thymocytes than in smaller, G0/G1 cells. Down-regulation of RAG-2 expression appears to occur before cells enter S phase, suggesting that RAG-2 function may be limited to noncycling cells.

Animals↗
PubMed1994

Negative control of the rat inhibin alpha subunit promoter in MA-10 Leydig tumour cells.

The promoter/regulatory sequences responsible for the transcription of the rat inhibin alpha subunit gene in the testis were identified by the transient expression in an MA-10 Leydig tumour cell line of a bacterial reporter gene, chloramphenicol acetyltransferase (CAT), which was driven by different regions of the 5' flanking sequence of the inhibin alpha subunit gene. The CAT activity was elevated when the 2.0 kb 5' flanking alpha subunit gene fragment was progressively shortened from its 5' end, and a maximal increase was reached when the CAT gene was driven by an alpha subunit gene promoter extending to -163 bp. This construct was termed A alpha BstCAT. Furthermore, when either the -2.0 to -1.6 kb or the -2.0 to -1.0 kb alpha subunit DNA fragment was fused to A alpha BstCAT, and CAT activity was markedly suppressed, indicating the presence of negative regulatory DNA elements (NREs) in the upstream region of the gene. The cyclic AMP (cAMP) responsiveness of the alpha subunit gene, which was dependent upon the putative cAMP response element within the 67 bp alpha subunit promoter, was not affected by the upstream NREs. The inhibitory effect was also demonstrated when the -2.0 to -1.0 kb fragment was placed in either orientation with respect to the alpha subunit promoter or to a thymidine kinase promoter, suggesting that the NRE(s) can act as a silencer. Based on our observations we conclude that the basal expression of the rat inhibin alpha subunit gene in testicular MA-10 cells may, at least in part, be controlled by the upstream silencer(s) and NRE(s).

Animals↗
PubMed1994

Regulators for the rat clusterin gene: DNA methylation and cis-acting regulatory elements.

Clusterin, also known as sulphated glycoprotein-2 or testosterone-repressed prostate message-2, is a ubiquitous protein found in a variety of tissues and species. In the reproductive tract of the male rat, clusterin is regulated in a complex age-dependent and cell-specific manner. It is expressed at high levels in the epididymis and testis and at very low levels in the prostate under basal conditions. The expression of this gene in the prostate and seminal vesicles is associated with androgen withdrawal, while in the testis clusterin mRNA is repressed by cyclic AMP (cAMP). To understand the mechanisms that control the expression of the clusterin gene better, we isolated and characterized the gene encoding rat clusterin, and analysed its cytosine methylation pattern in various tissues. Several putative regulatory DNA elements were identified, including a consensus AP-1 site in the 5' flanking region. Two AP-1 sites and two transforming growth factor-beta inhibitory elements, one AP-2 site and eight half-sites for glucocorticoid/androgen response elements were found within the first intron, and one cAMP response element was found in the first exon. The cytosine methylation pattern indicated that testicular or epididymal DNA in the rat is hypomethylated in the region between positions -534 and -99 of the clusterin gene, when compared with tissues with lower levels of expression such as prostate as well as liver, lung, kidney and spleen.

Animals↗
PubMed1994

Prognostic factors after hepatectomy for hepatocellular carcinoma.

During a seven and a half year period from 1985 through June 1992, hepatic resection was carried out on 84 patients with hepatocellular carcinoma. Their ages ranged from 10 to 79, with an average of 55 years. Hepatitis B surface antigen (HbsAg) was positive in 83%, an alfafetoprotein level of more than 20 ng/dl was found in 71%, and cirrhosis was noted in 64%. Surgical mortality was 3.6% and hospital mortality 1.2%. The 1-, 3- and 5-year actuarial survival rates, excluding in-hospital deaths, were 74%, 56% and 49%, respectively. The large number of patients operated on in the early stage (52%), and Child's class A (61%) might account for the low surgical mortality and high survival rate. The favorable conditions were identified as follows; no cirrhosis, surgery in the early stage, tumor size less than 5 cm, negative HbsAg and freedom from vascular involvement. Multivariate analysis showed that only negative HbsAg had better survival.

Adolescent↗
PubMed1994

Successful resection of a minute icteric hepatocellular carcinoma--case report.

A 38-year-old male was admitted to our department with jaundice. Imaging studies including ultrasonography, ERCP, PTC and computed tomography (CT) revealed a hilar lesion. Right hepatic lobectomy, caudate lobectomy, excision of CBD and restoration of biloenteric continuity was performed. Pathological examination showed an icteric hepatoma (1.2 x 0.8 x 0.8 cm in size) originating in the caudate lobe. The tumor thrombus occupied the common hepatic duct and the right intrahepatic duct. The postoperative course was fairly unremarkable, and the patient has remained in good health for four years after surgery without any sign of recurrence.

Adult↗
PubMed1994

Multiple mediastinal ganglioneuromas: report of a case.

A 23-year-old male known to have an asymptomatic mediastinal mass for four years was admitted due to progressive pitting edema of his arms and legs lasting for one week. The edema subsided prior to surgical extirpation of the left paraspinal mass. Initially recognized radiologically as a well-defined soft tissue mass with mottled calcification, on operation the mass was seen to be two well-encapsulated ganglioneuromas. Another small, round, nodular lesion abutted the contralateral side of the vertebral body on a computed tomographic scan of the chest. The postoperative course was unremarkable except for subsequently developed but well-tolerated regional anhidrosis involving the left side of the chest wall and the left upper limb.

Adult↗
PubMed1994

Epstein-Barr virus harboring in the parotid gland without tumor association.

The purpose of this study is to clarify the relationship between Epstein-Barr virus (EBV) and tumors of the major salivary gland. EBV DNA was detected by polymerase chain reaction (PCR) in parotid secretions in 56% of patients (n = 32) regardless of the presence of tumors in the parotid gland and in tumor tissues in 19% of surgical specimens (n = 21). By Southern blot-hybridization analysis, we found type A EBV in three patients and type B EBV in one patient. In situ hybridization for EBV genome was positive in surgical specimens of salivary glands in 33% of patients (n = 21). Our results suggest that this virus may not play a role in the pathogenesis of most tumors of the major salivary gland. However, two patients with lymphoepithelial carcinoma were found to have a close relationship to EBV as shown by high titers of antibodies in the sera against EBV related antigens by standard immunofluorescent technique and by the presence of many copies of EBV genome in tumor cells using in situ hybridization.

Adult↗
PubMed1994

Effects of novel antiarrhythmic agents, BRB-I-28 and its derivatives, on the heart mitochondrial respiratory chain and sarcoplasmic reticulum Ca(2+)-ATPase.

The effects of BRB-I-28 and its derivatives (GLG-V-13, SAZ-VII-22 and SAZ-VII-23), a novel group of antiarrhythmic agents, were investigated on the rat heart mitochondrial respiratory chain. The results indicate that BRB-I-28 and its derivatives have concentration-dependent inhibitory effects on NADH oxidase and NADH-CoQ reductase (complex I), but they have no significant effects on succinate oxidase, succinate dehydrogenase (complex II), CoQ-cytochrome c reductase (complex III), cytochrome c oxidase (complex IV), and NADH-K3Fe(CN)6 reductase. The site of inhibition of BRB-I-28 and its derivatives on the respiratory chain was localized between flavoprotein n (FPn) and CoQ, which is similar to the effect of rotenone and several other antiarrhythmic drugs such as amiodarone, propranolol, etc. BRB-I-28 and its derivatives also have significant inhibitory effects on mitochondrial ATPase activity as reported for other antiarrhythmic drugs such as amiodarone, propranolol, quinidine, and lidocaine. However, BRB-I-28 and its derivatives have no direct effects on sarcoplasmic reticulum Ca(2+)-ATPase activity. The inhibitory effects of BRB-I-28 and its derivatives on mitochondrial oxidative phosphorylation may result in the depletion of ATP. This effect, in combination with their effects on Na+,K(+)-ATPase, could possibly produce an increase in Ca2+ concentration in cytosol. This may be another mechanism by which these DHBCN derivatives produce an increase in systemic arterial blood pressure and contractile force of isolated cardiac muscle. On the other hand, inhibition on mitochondrial respiration may account for some of the potential toxic effects of these diheterabicyclo[3.3.1]nonane derivatives.

Adenosine Triphosphatases↗
PubMed1994

Video-assisted thoracoscopic T2 sympathectomy for hyperhidrosis palmaris.

BACKGROUND: Hyperhidrosis palmaris is a functionally and socially disabling problem. Thoracic sympathectomy of the T2 ganglion has proved to be the time-honored treatment modality. STUDY DESIGN: The results of this study demonstrate the effectiveness of video-assisted thoracoscope for treatment of hyperhidrosis palmaris. The possibility to apply different anesthetic techniques and to measure surface temperature change of the hand were documented as well. RESULTS: Eighty consecutive cases (159 procedures) of essential hyperhidrosis palmaris were treated by video-assisted thoracoscopic T2 sympathectomy between January 1991 and December 1992. The surgical results were classified as excellent (much improved, very dry) in 88.1 percent, good (improved, minimal wet) in 9.4 percent, and fair (slightly improved, still wet) in 2.5 percent of the patients. The postoperative complications included one prolonged air leakage, one hemothorax, two wound infections, and 15 cases of facial anhidrosis. There were no recurrent cases (mean follow-up, 14.5 months). Fifty-six patients had concomitant hyperhidrosis pedum. Interestingly enough, through unknown mechanism, 64.3 percent of the patients with concomitant hyperhidrosis pedum were cured after this procedure. CONCLUSIONS: Video-assisted thoracoscopy provides magnified surgical fields, which make thoracoscopic sympathectomy for hyperhidrosis palmaris an effective, safe, easy to use, and time-saving procedure. This technique is also excellent for teaching purposes and allows the assistant to participate in the operation.

Adolescent↗