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Biomedical subjects

C L Chen

Publications and source records attributed to C L Chen.

At least 73 records · Page 4Linked to original sources
PubMed2001

Successful liver transplantation in a child with biliary atresia and hepatopulmonary syndrome.

Hepatopulmonary syndrome (HPS) is characterized by hypoxemia in patients with severe chronic liver disease and pulmonary vasodilatation in the absence of primary cardiac or pulmonary disease. Severe hypoxemia resulting from HPS is generally considered a contraindication to liver transplantation. We describe the case of a 6-year-old girl with biliary atresia complicated with HPS who was successfully treated with liver transplantation. Cyanosis and dyspnea had initially developed at the age of 5 years. Arterial blood gas showed a PaO2 of 46.6 mm Hg on room air. The diagnosis of HPS was confirmed by contrast echocardiography, lung perfusion scan with 99mTc macroaggregate albumin, and pulmonary angiography. The lung scan revealed an intrapulmonary shunt of 24%. She underwent living donor liver transplantation and received a left lateral segment graft from her mother. One year after successful liver transplantation, she had normal arterial oxygen saturation and a normal lung scan without intrapulmonary shunting. This case demonstrates that HPS associated with end-stage liver disease is potentially curable by liver transplantation.

Biliary Atresia↗
PubMed2000

Roles of glucitol in the GutR-mediated transcription activation process in Bacillus subtilis: tight binding of GutR to tis binding site.

Glucitol induction in Bacillus subtilis requires a transcription activator, GutR, and a sequence located upstream of the gut promoter. To understand the initial steps involved in the GutR-mediated transcription activation process and the physiological roles of glucitol, GutR was overproduced and purified. In the absence of glucitol, GutR exists as a monomer and binds directly to its binding site in the gut regulatory region. This binding site was mapped to a 29-base pair imperfect inverted repeat located between -78 and -50, and there is only one GutR binding site within the regulatory region. The kinetic parameters of the interaction between GutR and its binding site were monitored in real time using surface plasmon resonance. The half-life of the GutR-DNA complex in the absence of glucitol was estimated to be 6.8 min. In contrast, in the presence of glucitol, the half-life of the complex was extended to longer than 19 h by affecting only the off-rate but not the on-rate. This effect is glucitol-specific. These data indicate that glucitol binds to GutR and induces GutR to have an extremely tight binding at its binding site. The physiological relevance of this process in transcription activation is discussed.

Bacillus subtilis↗
PubMed2000

Outflow tract reconstruction in living donor liver transplantation.

BACKGROUND: Hepatic venous reconstruction is critical in living donor liver transplantation because outflow obstruction may lead to graft dysfunction or loss. We describe our experience and analyze outcomes with a technique of creating a single outflow tract using venoplasties of the graft and recipient hepatic veins. PATIENTS AND METHODS: A retrospective study was done on 38 consecutive living donor liver transplants performed from June 1994 to March 2000. The grafts included 36 left-side grafts and 2 right-side grafts. Nine grafts had multiple hepatic veins and required a venoplasty of two or three hepatic veins to create a single outflow orifice. Triple recipient hepatic venoplasty was performed in 32 patients, double venoplasty in 5 and none in 1. RESULTS: There were four cases of outflow obstruction, three occurring in patients with a double recipient venoplasty. Two of the problems were remedied intraoperatively by adjusting the position of the graft although two were structural in nature and required the insertion of expandable metallic vascular stents. All donors and recipients with their original grafts are alive at a mean follow-up period of 27 months. CONCLUSION: A triple recipient venoplasty with a matching venoplasty of multiple graft hepatic veins to create a single wide outflow orifice is recommended in living donor liver transplantation using left side grafts.

Adolescent↗
PubMed2000

Lymphocytes lacking I kappa B-alpha develop normally, but have selective defects in proliferation and function.

NF-kappaB has been implicated in the development, activation, and function of B and T lymphocytes. We have evaluated the in vivo effects of deletion of IkappaB-alpha, a major inhibitor of NF-kappaB, on lymphocyte development, proliferation, and function. To elucidate the long term role of IkappaB-alpha in lymphocytes, fetal liver cells of 14.5-day-old IkappaB-alpha(-/-) or wild-type embryos were transplanted into irradiated recombinase-activating gene-2-deficient mice. Within 4 wk, the IkappaB-alpha(-/-) fetal liver cells reconstitute mature B and T cell populations in the recipients comparable to those produced by wild-type fetal liver cells. However, the proliferative responses of IkappaB-alpha(-/-) B cells are enhanced, whereas those of IkappaB-alpha(-/-) T cells are reduced. The levels of IgG1, IgG2a, IgA, and IgE produced by IkappaB-alpha(-/-) B cells are elevated relative to those produced by IkappaB-alpha(+/+) or IkappaB-alpha(+/-). Moreover, the specific immune responses to OVA and the generation of germinal centers are impaired in recipients of IkappaB-alpha(-/-) fetal liver cells. These results indicate that IkappaB-alpha plays a vital role in signal transduction pathways regulating lymphocyte proliferation and also in the production of specific Ig isotypes.

Animals↗
PubMed2000

Highly sensitive liquid chromatography-electrospray mass spectrometry (LC-MS) method for the determination of etoposide levels in human serum and plasma.

Etoposide is one of the most commonly used antineoplastic agents. A highly sensitive liquid chromatography-electrospray mass spectrometry (LC-MS) method was developed for the determination of etoposide in human serum and plasma. Etoposide was extracted with chloroform and extracts were reconstituted in acetonitrile followed by the evaporation of chloroform with nitrogen gas. Etoposide was separated using Lichospher 100 RP-18 (5 microm) column (250 mmx4 mm) with the mobile phase of acetonitrile-water containing 0.1% acetic acid (45/55, v/v) at flow-rate of 0.5 ml/min. Selected-ion monitoring (SIM) mode was performed on m/z 589 (positive ion mode) using a fragmentor of 75 V. Good linearity (r>0.9965) was observed between concentrations of 0.0125-5 microM in 200 microl serum and 0.01-10 microM in 100 microl plasma. Intra- and inter-assay variabilities were less than 7% and the lowest detection limit of etoposide was 0.005 microM in both serum and plasma at a signal-to-noise ratio of approximately 4. The etoposide concentrations in four cancer patients treated with etoposide are also presented to demonstrate the clinical utility of this new method, which should aid the pharmacokinetically guided use of etoposide in clinical settings.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Enhanced hydroxychavicol-induced cytotoxic effects in glutathione-depleted HepG2 cells.

Hydroxychavicol (HC) is the major safrole urinary metabolite in rats and humans. The cytotoxic potential of HC in metabolically competent cells has yet to be studied. HC alone was slightly toxic to HepG2 cells. However, the cytotoxicity increased significantly (P<0.05) when HepG2 cells were pretreated with buthionine sulfoximine (BSO), suggesting that endogenous glutathione participates in HC-induced cytotoxicity. Addition of catalase or N-acetylcysteine prevented the BSO plus HC-mediated cytotoxicity. HC also increased 8-hydroxy-2'-deoxyguanosine formation and apoptosis in BSO-pretreated HepG2 cells and this increase could also be suppressed by catalase. These data suggest that BSO pretreatment enhanced HC-induced cytotoxic effects in HepG2 cells, which are related to oxidative DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Minimal blood loss living donor hepatectomy.

BACKGROUND: Donor hepatectomy with maximal safety while preserving graft viability is of principal concern in living donor liver transplantation. There are compelling reasons for avoiding blood transfusion, even with autologous blood, to avoid the potential risks it imposes on healthy donors. This study aims to describe the surgical technique and clinical outcomes of living donor hepatectomy with minimal blood loss requiring no blood transfusion. METHODS: Donor hepatectomy was performed in 30 living donors according to a detailed preoperative imaging study of the vascular and biliary anatomy. Liver parenchymal transection was carried out with strict adherence to a meticulous surgical technique without vascular inflow occlusion to either side of the liver. Pre-, intra-, and postoperative data were gathered, and factors related to blood loss were analyzed retrospectively. RESULTS: The intraoperative blood loss ranged from 20 to 300 ml with a mean of 72.0+/-58.9 ml (median, 55 ml), and neither homologous nor autologous blood transfusion was required in any of the donors intra- and postoperatively. All 30 donors were discharged with minimal complications, and remain well at a mean follow-up of 24 months after donation. Excellent graft viability was verified by the fact that all 30 recipients are alive and well with a few manageable complications. The actual graft and patient survival are both 100% at the time of writing. CONCLUSIONS: Regardless of the extent of donor hepatectomy, blood loss can and should be kept to a minimum, and living donor hepatectomy without blood transfusion is a realistic objective.

Adolescent↗
PubMed2000

Humic acid-induced echinocyte transformation in human erythrocytes: characterization of morphological changes and determination of the mechanism underlying damage.

Blackfoot disease (BFD) is a peripheral arterial occlusive disease found among human inhabitants along the southwest coast of Taiwan. Well water used for drinking and cooking contains humic acid (HA), which may be a possible etiological factor. In this study, HA toxicity was investigated in human erythrocytes and was found to induce echinocytic formation. Morphological changes occurred in both a concentration- and time-dependent fashion. The presence of HA was also observed to facilitate the loading of erythrocytes with excess Ca(2+) (1 mM), which may have occurred following permeability changes in cell membranes, leading to echinocytic transformations. Sodium dodecyl sulfate (SDS) gel electrophoresis indicated that echinocyte formation was due to the oxidation of normal membrane proteins that were replaced by high-molecular-weight proteins. Humic acid also induced hemoglobin oxidation in erythrocytes. Data show that oxidative stress generated by HA as well as direct effects were exerted on the cytoskeleton of erythrocytes, and these may be significant factors in the etiology of BFD.

Anemia↗
PubMed2000

Arecoline excites rat locus coeruleus neurons by activating the M2-muscarinic receptor.

The action of arecoline on rat locus coeruleus neurons was studied by intracellular recording from the in vitro brain slice preparation. Superfusion of arecoline (0.1-100 microM) caused two dose-related effects, an increased firing rate and, in neurons previously hyperpolarized to a constant potential by passing a steady hyperpolarizing current across the membrane, depolarization. Both effects were associated with a reduction in membrane input resistance. Moreover, the arecoline-induced excitatory effects were antagonized by the muscarinic receptor antagonist, atropine, but not by the nicotinic receptor antagonist, hexamethonium. Methoctramine, a selective M2-muscarinic receptor antagonist, was also effective in reversing the arecoline-induced effects, with a dissociation equilibrium constant of 14.2+/-1.2 nM (n=6). These results therefore suggest that arecoline exerts its excitatory actions by binding to M2-muscarinic receptors on the cell membrane of neurons of the locus coeruleus.

Alzheimer Disease↗
PubMed2000

Telomerase activity in rat liver allografts.

BACKGROUND: Telomerase activity in grafts may be involved in the alteration of cellular senescence after transplantation or its relevant immunological events. METHODS: At the age of 20 weeks, donor livers harvested from DA (RT1a) were orthotopically transplanted into PVG (RT1c) or LEW (RT1(1)) rats. Rats having undergone orthotopic liver transplantation (OLT; DA-PVG) naturally overcome rejection, whereas all OLT (DA-LEW) rats die from acute rejection within 14 days. Telomerase activity in liver allografts was measured at various intervals post OLT. RESULTS: At day 7 when the most severe rejection episode was observed in OLT (DA-LEW) and OLT (DA-PVG), the telomerase activity was significantly higher than in syngeneic OLT (DA-DA) rats, in which no rejection occurred. Telomerase activity in tolerogenic OLT (DA-PVG) livers remained elevated for at least 2 months. CONCLUSION: These results suggest that telomerase activity in allogeneic OLT livers may reflect regenerating hepatocytes or activation of lymphocytes and/or hematopoietic stem cells associated with rejection or tolerance.

Animals↗
PubMed2000

Nuclear factor-kappaB/Rel is apoptogenic in cytokine withdrawal-induced programmed cell death.

In the complex microenvironment where they evolve, developing cells undergo rapid programmed cell death (PCD) when cytokines that support them become limiting. The transcriptional mechanisms of cytokine-withdrawal apoptosis are poorly understood. In this report, we used early B-lymphocyte tissue culture and transgenic cells to demonstrate that nuclear factor-kappaB (NF-kappaB) promotes apoptosis during cytokine withdrawal-induced PCD. In the progenitor B lymphocyte model FL5.12, whereas NF-kappaB has an antiapoptotic function in response to tumor necrosis factor-alpha, cytokine withdrawal causes nuclear translocation of NF-kappaB/cRel, where it is apoptogenic. Inhibition of NF-kappaB activation delays cytokine withdrawal-induced PCD in both FL5.12 and transgenic early B cells. Additionally, reconstituting a bone marrow microenvironment ex vivo abrogates the differential apoptotic pattern between control and transgenic early B cells.

Apoptosis↗
PubMed2000

Expression of the Epstein-Barr virus BHRF1 gene, a homologue of Bcl-2, in nasopharyngeal carcinoma tissue.

Epstein-Barr virus (EBV) infection is associated closely with the pathogenesis of nasopharyngeal carcinoma (NPC). The EBV gene product, BHRF1, has been demonstrated in vitro and is structurally and functionally similar to the oncogene bcl-2, that is able to protect cells from programmed cell death. To determine whether the BHRF1 gene is expressed in vivo, BHRF1 mRNA or protein were sought in tissues from NPC and non-NPC patients. BHRF1 transcripts were specifically detected in the NPC tumours (32 out of 44, 72.7%) rather than the non-NPC tissues (0 out of 25) by reverse transcription, polymerase chain reaction and Southern hybridization. Other EBV genes, such as the lytic gene BZLF1 and latent genes EBNA1 and LMP2A, were also investigated. BZLF1 transcripts also were found specifically in NPC tumours (33 out of 44, 75%). EBNA1 was expressed in 79.5% of NPC, and 28% of non- NPC, tissues and LMP2A was expressed in 70.5% of NPC, and 88% of non-NPC, tissues. BHRF1 protein was detected by immunohistochemistry in 4 metastatic NPC, of 36 NPC tissue sections available. The BHRF1 protein was distributed in both the nucleus and cytoplasm of the neoplastic epithelial cells. IgG antibody against the BHRF1 protein was detected in 6 of 17 (35. 3%) NPC plasma, but the protein and IgG were both absent from the non-NPC controls. BHRF1 DNA sequences were determined for 11 NPC and 3 non-NPC samples. No sequence was specific for the EBV isolates from NPC tissue. Amino acids 79 and 88 always appeared in the same form, however, for every tested isolate and both were valine or leucine. This particular characteristic was not present in the B95-8 strain or in the corresponding regions of homologues, Bcl-2 and Bcl-XL, and was regarded as unique to Oriental EBV strains.

Amino Acids↗
PubMed2000

Chemotherapy alone versus surgery followed by chemotherapy for stage I/IIE large-cell lymphoma of the stomach.

The optimal treatment of localized large-cell lymphoma of the stomach remains controversial. In particular, the role of surgical resection of the primary tumor needs to be clearly defined. We have reviewed all patients with a diagnosis of gastric lymphoma and treated in our institutions between 1988 and 1998. Patients fulfilling the following criteria were included in this study: (1) histologically proven large-cell lymphoma of the stomach; (2) adequate pathological materials and complete clinical information for analysis; (3) clinical stage I/II disease according to the Musshoff modification of Ann Arbor system; and (4) received primary chemotherapy alone with anthracycline- or anthracenedione-containing regimens (group A) or curative surgery followed by adjuvant chemotherapy (group B). There were 38 and 21 patients in group A and group B, respectively. All pertinent clinicopathologic features were similar between the two groups of patients, except that patients of group A had significantly more stage II-2 disease (P = 0.004). Of group A, among 36 patients who could be evaluated for response to chemotherapy, there were 29 complete and 1 partial responses, with an overall response rate of 83.3% (95% CI, 71.1-95.5%). The projected 5-year relapse-free survival (RFS) and overall survival (OS) were 86.0% (95% CI, 73.3-98.7%) and 72.6% (95% CI, 57.0-88.2%), respectively. On the other hand, the projected 5-year RFS and OS of group B were 77.9% (95% CI, 58.0-97.8%) and 77.8% (95% CI, 57.9-97. 7%), respectively, not significantly different from that of group A. Our data suggest that systemic chemotherapy alone may be a reasonable alternative treatment for stage I/II large-cell lymphoma of the stomach. Resection of the primary tumor before systemic chemotherapy does not appear to improve the cure rate of this group of patients.

Adult↗
PubMed2000

Isolation and characterisation of a serum lectin from blue gourami, Trichogaster trichopterus (Pallus).

A novel lectin, designated BGL, has been purified from the serum of blue gourami, Trichogaster trichopterus, with the use of (NH4)2SO4 fractionation, affinity chromatography and gel filtration chromatography. Electrophoretic analyses and mass spectrometric study of purified BGL showed that the lectin is composed of two isoforms with native molecular masses estimated to be 65 and 66 kDa, and two subunits of 32 and 34 kDa on SDS-PAGE under non-reducing conditions. Upon reduction with 20 mM dithiothreitol (DTT), BGL showed two close bands of 27 and 29 kDa. After isoelectric focusing, the lectin focused as close double bands at pH 5.6. The N-termini of both isoforms share the same sequence (HGEENRXGPR) and show no significant homology with any known proteins. The BGL agglutinating activity is specifically inhibited by N-acetyl-D-galactosamine and N-acetyl-D-glucosamine, and to a lesser degree by D-(+)-mannose, but not by D-(+)-galactose, D-(+)-glucose, maltose or N-acetyl-D-mannosamine. Haemagglutination assay showed that BGL is more specific for rabbit than mouse, chicken, rat or guinea pig erythrocytes, and haemagglutination was Ca2+-dependent. In addition, BGL could agglutinate a range of micro-organisms and yeast cells, with the exception of some fish pathogens, such as Aeromonas hydrophila (strains: PPD 134/91 and PPD 11/90) and Vibrio harveyi (strain: W618). Localisation of BGL by fluorescein isothiocyanate (FITC)-labelled antibodies revealed that the lectin is associated with the cell surface of fish leukocytes.

Agglutination↗
PubMed2000

Cloning and expression of the chicken immunoglobulin joining (J)-chain cDNA.

The J chain is a component of polymeric immunoglobulin (Ig) molecules and may play an important role in their polymerization and the transport of polymeric Ig across epithelial cells. In this study, the primary structure of the chicken J chain was determined by sequencing cDNA clones. The cDNA had an open reading frame of 476 nucleotides encoding a putative protein of 158 amino acid residues including the signal sequence. The 3' untranslated region consisted of 1216 nucleotides and a poly(A) tail. The deduced amino acid sequence of the chicken J chain had a high degree of homology to that of human, cow, rabbit, mouse, frog, and earthworm, with eight conserved Cys residues identical to the mammalian J chains. Northern blot hybridization performed with total RNA from various chicken tissues revealed high levels of J-chain mRNA expression in spleen, intestine, Harderian gland, and bursa of Fabricius, and low levels in the thymus. The J chain was expressed in the bursa as early as day 15 of embryogenesis. These data indicated that the chicken J-chain gene displays a high degree of homology with that of other species, and is expressed at an early stage of development of the chicken immune system.

Amino Acid Sequence↗
PubMed2000

Cerebral vasculitis in Henoch-Schönlein purpura: a case report with sequential magnetic resonance imaging changes and treated with plasmapheresis alone.

Neurological complications are rare during the course of Henoch-Schönlein purpura (HSP). We report a 7-year-old girl with HSP who presented with seizures, loss of vision and disturbance of consciousness. Magnetic resonance imaging (MRI) showed high signal intensity in the gray and white matter over the left parietal and both occipital lobes, compatible with MRI findings of cerebral vasculitis. The eye fundi revealed multiple branches of retinal artery occlusion. Intravenous pulse methylprednisolone (MTP) followed by oral steroid therapy was initially administered for HSP nephritis. Cerebral vasculitis developed 10 days post-MTP treatment, with progressive worsening of consciousness. Oral steroid was discontinued and plasmapheresis was performed alone. Her level of consciousness dramatically improved after plasmapheresis. The brain MRI and eye fundi findings were consistent with her clinical improvement. To the best of our knowledge, this is the first description of MRI abnormalities and multiple retinal artery branch occlusion of cerebral vasculitis in a patient with HSP that was successfully treated by plasmapheresis alone. In conclusion, we propose that plasmapheresis may be used as a first-line therapy or rescue therapy for cerebral vasculitis in HSP.

Anti-Inflammatory Agents↗
PubMed2000

A new approach to applying feedforward neural networks to the prediction of musculoskeletal disorder risk.

A new and improved method to feedforward neural network (FNN) development for application to data classification problems, such as the prediction of levels of low-back disorder (LBD) risk associated with industrial jobs, is presented. Background on FNN development for data classification is provided along with discussions of previous research and neighborhood (local) solution search methods for hard combinatorial problems. An analytical study is presented which compared prediction accuracy of a FNN based on an error-back propagation (EBP) algorithm with the accuracy of a FNN developed by considering results of local solution search (simulated annealing) for classifying industrial jobs as posing low or high risk for LBDs. The comparison demonstrated superior performance of the FNN generated using the new method. The architecture of this FNN included fewer input (predictor) variables and hidden neurons than the FNN developed based on the EBP algorithm. Independent variable selection methods and the phenomenon of 'overfitting' in FNN (and statistical model) generation for data classification are discussed. The results are supportive of the use of the new approach to FNN development for applications to musculoskeletal disorders and risk forecasting in other domains.

Back Injuries↗