Biomedical subjects

C M Chen

Publications and source records attributed to C M Chen.

At least 199 records · Page 11Linked to original sources

PubMed1994

Analysis of deletion of the integrated human papillomavirus 16 sequence in cervical cancer: a rapid multiplex polymerase chain reaction approach.

A protocol for a rapid physical mapping of the integrated type 16 human papillomavirus (HPV16) sequences in biopsied and paraffin-embedded archival cervical cancer samples is described. The procedure involves the use of an anchor primer and a mixture of indicator primers in a multiplex polymerase chain reaction (PCR). A minimal conserved region of viral integration of 2,745 bp in length has been mapped between nucleotide (nt) 6102-941, containing the entire regulatory region and the E6 and E7 open reading frames (ORFs). A general deletion domain of 1,465 bp in the integrated viral genome has been defined between nt 1417-2881, covering most of the E1 ORF at the 3'-half and 60 bp at the 5' terminus of the E2 ORF. This common deleted sequence contains an ATPase active domain speculated to be associated with a DNA helicase function essential for the viral replication, and it also falls within the actively spliced E1-E2 segment of the primary RNA transcripts. Detection of the loss of the 3'-half of the E1 ORF would be an ideal marker for PCR-based rapid determination of HPV integration in cervical cancer cells.

Chromosome Mapping↗

PubMed1994

Response to supplementary vaccination with recombinant or plasma hepatitis B vaccine in healthy non-responding children.

Fifty-three children who failed to respond to four doses of plasma hepatitis B (HB) vaccine (anti-HBs titre < 10 IU l-1) were divided into two groups and received revaccination with either three doses of recombinant HB vaccine (10 micrograms/dose, by 0, 1, 6 month schedule; group A) or two additional doses of plasma HB vaccine (5 micrograms/dose, by 0, 1 month schedule; group B) respectively. Thirty-two vaccinees in group A had a response rate (with anti-HBs > 10 IU l-1) of 53.1% (17/32), 87.5% (28/32), and 100% (32/32) after first, second and third doses of the vaccine respectively. Twenty-one vaccinees in group B had a response rate of 61.9% (13/21) after two additional doses of plasma vaccine. High anti-HBs titres (> 1000 IU l-1) were noted in 50% of the vaccinees in group A after three doses of vaccine. Comparing anti-HBs response between group A and group B after two additional doses of HB vaccine, group A had a higher anti-HBs titre (geometric mean titre 104.7 IU l-1 versus 75.9 IU l-1) along with a better seroconversion rate (87.5 versus 61.9%). However, the differences in vaccine dose between the two groups may also be a contributory factor. Our findings indicate that three doses of recombinant HB vaccine were invariably effective in eliciting a good immune response in previous non-responders to the four doses of plasma HB vaccine. Therefore, it is speculated that these young vaccinees who did not respond to four doses of plasma HB vaccine may not be real non-responders, but hyporesponders.

Child↗

PubMed1994

Characterization of human immunodeficiency virus type 1 variants with increased resistance to a C2-symmetric protease inhibitor.

Inhibitors of the human immunodeficiency virus type 1 protease represent a promising class of antiviral drugs for the treatment of AIDS, and several are now in clinical trials. Here, we report the in vitro selection of viral variants with decreased sensitivity to a C2-symmetric protease inhibitor (A-77003). We show that a single amino acid substitution (Arg to Gln or Lys) at position 8 of the protease results in a substantial decrease in the inhibitory activity of the drug on the enzyme and a comparable increase in viral resistance. These findings, when analyzed by using the three-dimensional structure of the protease-drug complex, provide a strategic guide for the future development of inhibitors of the human immunodeficiency virus type 1 protease.

Amino Acid Sequence↗

PubMed1994

MELAS syndrome with mitochondrial tRNA(Leu(UUR)) gene mutation in a Chinese family.

The clinical features of a patient in a Chinese family with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS syndrome) are reported. The study revealed that hearing and visual impairments and miscarriages may be early clinical presentations in MELAS. A heteroplasmic A to G transition in the tRNA(Leu(UUR)) gene was noted at the nucleotide pair 3243 in the mitochondrial DNA of muscle, blood, and hair follicles of the proband and his maternal relatives. Quantitative analysis of the mutated mitochondrial DNA revealed variable proportions in different tissues and subjects of maternal lineage in the family. Muscle tissue contained a higher proportion of the mutant mitochondria than other tissues examined. The function of the reproductive system of the proband seems to be impaired. In one clinically healthy sibling, the 3243rd point mutation was found in sperm mitochondrial DNA, although sperm motility was not affected. It seems that biochemical defects in mitochondrial respiration and oxidative phosphorylation are tissue specific expressions of the 3243rd point mutation in the mitochondrial DNA of the affected target tissues.

Adolescent↗

PubMed1994

Signal transduction by the growth hormone receptor.

It has been proposed that dimerization of identical receptor subunits by growth hormone (GH) is the mechanism of signal transduction across the cell membrane. We present here data with analogs of porcine GH (pGH), with GH receptors (GHR) mutated in the dimerization domain and with monoclonal antibodies to the GHR which indicate that dimerization is necessary but not sufficient for transduction. We also report nuclear uptake of GH both in vivo and in vitro, along with nuclear localization of the receptor and GH-binding protein (GHBP). This suggests that GH acts directly at the nucleus, and one possible target for this action is a rapid increase in transcription of C/EBP delta seen in 3T3-F442A cells in response to GH. This tyrosine kinase-dependent event may be an archetype for induction of other immediate early gene transcription factors which then interact to determine the programming of the subsequent transcriptional response to GH.

Animals↗

PubMed1994

An experimental model of osteoarthritis in rabbit.

BACKGROUND: From both a microscopic and a metabolic view, experimental animal models are very important for study of the pathogenesis of osteoarthritis. A new, different operative procedure was used in rabbit models, and the pathologic findings were evaluated. METHODS: Twelve New Zealand white rabbits were divided into six groups; eight were used as animal models and four, for drug efficacy study. Transection of the anterior cruciate and medial collateral ligaments on the left knee joint, and sham-operation were performed on the right knee joint. Rabbits were sacrificed post surgery from 4, 6, 8 and 12 weeks. Eight parameters from gross to microscopic findings were used in order to evaluate osteoarthritic changes. Indomethacin and aspirin were chosen for the drug efficacy experiment; the two rabbits of each group were sacrificed at the end of the sixth week post-surgery. RESULTS: According to pathological findings, this operative procedure can produce osteoarthritic changes, visible both microscopically and macroscopically. There were osteoarthritic changes in the fourth week post-surgery group and, obviously, in the eighth week; these persisted until 12th weeks post-surgery. Neither indomethacin nor aspirin showed any effect in preventing osteoarthritis progression. CONCLUSIONS: Transection of the anterior cruciate and medial collateral ligament rabbit model can produce osteoarthritic lesions in the knee joint. This model can be used for further biochemical and metabolic studies.

Animals↗

PubMed1994

Induction of aggregation and augmentation of protein kinase-mediated phosphorylation of purified vimentin intermediate filaments by withangulatin A.

Purified assembly-competent vimentin, an intermediate filament protein, was obtained from bovine lens in this study. The effects of withangulatin A on vimentin assembly with or without phosphorylation were examined by negative-stain electron microscopy. Soluble tetrameric vimentin was assembled into irregular fibrils with lateral associations or short filaments after pretreatment with 50 or 100 microM withangulatin A, respectively. Incubation of assembled vimentin filaments with withangulatin A at 50 or 100 microM resulted in the formation of aggregates, and the degree of aggregation was concentration dependent. The appearance of vimentin filaments was slightly altered after treatment with cAMP-dependent protein kinase or protein kinase C; however, phosphorylation of filamentous vimentin by the protein kinases in the presence of withangulatin A resulted in higher degrees of aggregation of the filaments, compared with those treated only with the drug. Moreover, the level of phosphorylation of filamentous vimentin by the protein kinases was augmented in the presence of withangulatin A. Experimental results indicated that withangulatin A directly and specifically affects the conformation of the vimentin molecules, thereby resulting in alterations in assembly behavior and reactivity toward cAMP-dependent protein kinase and protein kinase C. The data observed further imply that withangulatin A, which directly causes aggregation of vimentin filaments, is a vimentin intermediate filament-targeting drug.

Animals↗

PubMed1994

Intermittent intravenous treatment of lupus nephritis with cyclophosphamide: a four-year experience with twenty-four patients.

BACKGROUND: Renal involvement in systemic lupus erythematosus commonly leads to renal failure and death. We conducted a study to evaluate the efficacy and side effects of intermittent intravenous treatment with cyclophosphamide of patients with lupus nephritis. METHODS: Twenty-four patients with lupus nephritis were recruited at Tri-Service General Hospital from 1988 to 1992. Cyclophosphamide was administered intravenously monthly for three months, and then every three months. 24-hour urinary protein, creatinine clearance, serum creatinine, blood urea nitrogen, C3 and C4 levels, serum albumin, hemoglobin, and dosage of prednisolone were recorded before each treatment. During treatment, the side effects were monitored. RESULTS: Two patients progressed to renal failure within one year and one patient after three years. Fifteen patients completed therapy for one year. Among these 15 patients, the levels of hemoglobin, serum albumin, and C3 significantly increased at six months, then became stable; the level of C4 increased at 12 months. In contrast, the dosage of prednisolone decreased significantly at six months. There was no significant difference of creatinine clearance, 24-hour urinary protein, serum creatinine, and blood urea nitrogen before and after treatment. The most common side effects were nausea and vomiting. No severe side effect necessitated discontinuing therapy with cyclophosphamide. CONCLUSIONS: Intermittent intravenous therapy in lupus nephritis with cyclophosphamide can significantly increase levels of hemoglobin, serum albumin, C3 and C4, and keep renal function stable. Poor response was found in a subset of patients. The side effects were mild in the present study.

Adult↗

PubMed1994

Bateman bipolar hemiarthroplasty for displaced intracapsular femoral neck fractures. Uncemented versus cemented.

Four hundred forty-seven patients with 451 displaced fractures of the femoral neck were treated with Bateman bipolar hemiarthroplasty (190 cemented and 261 uncemented) between 1985 and 1990 in the authors' institution. During a follow-up period of at least two years, the authors found less thigh pain (13% versus 46.2%) and higher Harris hip scores (86 versus 79) in the cemented group in comparison with the uncemented group. Radiographic examination showed less radiolucent zones and subsidence in the cemented group. Heterotopic ossification was more common in the cemented group. Despite the fact that the cemented group had longer operative times (average, 20 minutes) and more blood loss (average, 160 ml) during the operation, there was no significant difference in the early mortality rate observed between these two groups. The cemented prostheses provided better functional and radiographic results and fewer failures in the early stage. In addition, the cemented prostheses did not lead to more complications and higher mortality rates. Thus, for elderly patients who need early ambulation and functional recovery, the cemented Bateman bipolar prosthesis appears to be a better choice than the uncemented Bateman prosthesis.

Aged↗

PubMed1994

[Experience of anesthesia during transthoracic endoscopic sympathectomy for palmar hyperhidrosis: comparison between double-lumen endobronchial tube ventilation and laryngeal mask ventilation].

In the past year we had 36 patients operated for transthoracic endoscopic sympathectomy to treat palmar hyperhidrosis. The first group composed of 17 patients receiving anesthesia with double-lumen endobronchial-tube ventilation from July-92 to April-93, and the second group composed of 19 patients receiving anesthesia with laryngeal mask ventilation from April-93 to August-93. During right lung collapse for sympathectomy, the first group patients' SaO2 (oxygen saturation) decreased from 99.65 +/- 0.62 mmHg (pre-operation) to 95.12 +/- 5.48 mmHg (at cauterization), 95.24 +/- 5.41 mmHg (5 minutes after cauterization) and resumed 99.53 +/- 0.62 mmHg after the procedure completed. During left lung collapse for left side sympathectomy, the same group patients' SaO2 decreased from 99.59 +/- 0.62 mmHg to 97.35 +/- 3.06 mmHg, 97.82 +/- 2.53 mmHg and resumed 99.65 +/- 0.49 mmHg respectively. The second group using laryngeal mask ventilation had SaO2 changes during right side sympathectomy from 99.68 +/- 0.58 mmHg (pre-cauterization) to 99.74 +/- 0.45 mmHg (when cauterization), 99.79 +/- 0.42 mmHg (5 minutes after cauterization) and resumed 99.84 +/- 0.37 mmHg after the procedure completed. During left side sympathectomy the second group patients' SaO2 changed from 99.84 +/- 0.39 mmHg to 99.42 +/- 1.50 mmHg, 99.47 +/- 1.46 mmHg and resumed 99.74 +/- 0.59 mmHg respectively. After 2-Way ANOVA with repeated measures of the SaO2 value, we could see that no matter what side operation, there were differences existed between these two groups (< 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Induction of vimentin modification and vimentin-HSP72 association by withangulatin A in 9L rat brain tumor cells.

Withangulatin A induced cell rounding up and the morphological alteration resulted from the reorganization of all of the major cytoskeletal components, i.e., vimentin, tubulin, and actin, as revealed by immunofluorescence techniques. When the withangulatin A-treated cells changed to a round-up morphology, vimentin intermediate filaments were found to be collapsed and clustered around the nucleus. The alteration was accompanied by characteristic changes of vimentin molecules, including augmentation of phosphorylation, retardation of electrophoretic mobility, and decrease in detergent extractability. The levels of vimentin phosphorylation were augmented by 2.5- and 1.8-fold in cells incubated with 50 microM withangulatin A for 1 and 3 h, respectively. The electrophoretic mobility of vimentin was partially retarded in cells treated with withangulatin A for 1 h at 10 microM and a completely upshift mobility was observed after 5 h treatment at 50 microM. In addition, vimentin molecules became less extractable by nonident P-40 after the cells were treated with withangulatin A and this effect was dose dependent. The decrease in solubility of vimentin was accompanied by the redistribution of HSP72 into the detergent nonextractable fraction and these two events were well correlated. Our results suggest that withangulatin A induced the modification of vimentin, which resulted in the alteration of cell morphology and redistribution of intracellular HSP72, an event that may play an important role in the induction of heat-shock response.

Animals↗

PubMed1993

Genomic organisation of a virulent Taiwanese strain of transmissible gastroenteritis virus.

Transmissible gastroenteritis (TGE) infection causes 65% of infectious piglet diarrhoea in Taiwan. A virulent Taiwanese strain, TFI, of transmissible gastroenteritis virus (TGEV) from a field outbreak was isolated in cell culture and plaque purified. Phenotypic differences were observed in the ability of TFI to infect certain cell lines. TGEV strains TLM-83 (PRCV Belgium), TO-163 (TGEV Japan) and Purdue-115 (TGEV USA) infected both ST (swine testis) and RPTG (pig kidney) cell lines whereas TFI infected ST but not RPTG cells. To investigate this phenotypic variation cDNA was generated from TFI genomic and amplified by PCR with oligonucleotides derived from published TGEV sequence data. An 8.4kb cDNA derived from the 3'-end of the TFI genome was sequenced. Eight ORFs, corresponding to the three structural protein genes, four potential genes and the 3'-end of an incomplete ORF whose amino acid sequence corresponded to the carboxyl end of the 1b subunit of the polymerase gene, were identified on the TFI sequence. The overall sequence similarity of TFI with the other TGEV strains was over 97%. However, several deletions, insertions and point mutations were found on the TFI sequence when compared with other TGEV strains. The TFI S protein was found to contain 1449 amino acids, as also identified for the FS772/70 and Miller TGEV strains, but two amino acids longer than the Purdue S protein. The TFI ORF-3a gene encodes 72 amino acids, however, a 37 nucleotide deletion was found 16 nucleotides downstream of the TFI ORF-3a stop codon.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1993

The use of PCR genome mapping for the characterisation of TGEV strains.

Previous studies on different transmissible gastroenteritis virus (TGEV) strains, including porcine respiratory coronavirus (PRCV), have identified regions within the genome that are polymorphic as regards insertions and deletions. For example the 672 base deletion within the S gene and multiple deletions 5', within and 3' of the ORF-3a gene were detected in strains of PRCV. The presence of deletions may be associated with a change in the virulence, attenuation or tissue tropism of the isolate. The Nouzilly (188-SG) TGEV vaccine strain was attenuated by passage of a cell culture adapted virulent isolate D-52 188 times through swine testis cells after treatment with gastric juice. PCR amplification with oligonucleotides, corresponding to known TGEV sequences, were used to analyse D-52 and 188-SG for genetic variation. Results with several pairs of oligonucleotides within the first 1565 nucleotides of the S gene did not identify a deletion within this region of the genome from either strain. However, oligonucleotides directed against the ORF-3a/3b region detected a deletion of about 250 nucleotides within the 188-SG genome but not in the D-52 genome. Since all the attenuated TGEV strains so far sequenced, PRCV, Miller SP and 188-SG, contained deletions within the ORF-3a/3b, it would suggest that this region of the TGEV genome is involved in regulating viral virulence.

Amino Acid Sequence↗

PubMed1993

Clinical and sonographic assessment of liver size in normal Chinese neonates.

Liver size and midclavicular line were measured by clinical and sonographic methods in 145 normal Chinese neonates with gestational ages of 34-42 weeks. The liver span, measured by clinical methods with percussion and percussion/palpation methods, correlated well with that measured by sonography (r = 0.73 and r = 0.76, respectively) for the entire sample. The liver spans (mean +/- SD) obtained by sonography were 4.24 +/- 0.63 cm and 4.58 +/- 0.56 cm in the preterm and term neonates, respectively. The liver span (sonography) and the distance of the liver edge below the right costal margin were weakly related in the term neonates (r = 0.36), but unrelated in the preterm neonates. We conclude that the liver span is a better estimate of liver size than the distance below the right coastal margin in normal neonates. We also found that the mean liver span is approximately 1 cm smaller in Chinese neonates than in Western neonates.

Biometry↗

PubMed1993

Elevation of plasma immunoglobulin A in the spontaneously hypertensive rat.

Prior studies describe deficiencies of T-cell-mediated immunity in the spontaneously hypertensive rat (SHR) strain of Okamoto and Aoki. This report describes an alteration of humoral immunity: elevation of the plasma concentration of immunoglobulin (Ig) A and of circulating IgA autoantibodies to single-stranded DNA, double-stranded DNA, and thyroglobulin. The increased plasma IgA levels are evident in prehypertensive SHR, hence not secondary to the hypertension, and they result mainly from increments in polymeric IgA. Plasma IgA content also varied concordantly with the level of systolic blood pressure as influenced by age (older > younger) and gender (male > female) in both the SHR and control Wistar-Kyoto rat strains. Strain differences in plasma IgG or IgM were not observed. Studies of peripheral blood lymphocytes indicate that increased production of IgA is one mechanism for the increment in plasma content. The number of blood lymphocytes capable of producing IgA in vitro in response to the mitogen lipopolysaccharide is increased in SHR. When cultured in the absence or presence of lipopolysaccharide, peripheral blood lymphocytes of SHR secrete more IgA in vitro than do cells of the control strain. No significant strain differences in biliary or renal excretion of IgA were observed. The observed alterations of IgA in the SHR either are causative factors in the development of the hypertension or are the products of an epiphenomenon in which IgA and blood pressure are affected separately, but in parallel, by causative factors related to rat strain, age, and gender.

Animals↗

PubMed1993

Subcapsular hemorrhage of the liver in a neonate with extremely low birthweight.

Subcapsular hemorrhage of the liver (SHL) is usually an autopsy finding rather than a clinical diagnosis. Recent literature has noted an increased incidence of SHL in premature infants. A 26-week, 899 g female was born via emergency cesarean section due to excessive vaginal bleeding. At birth and during the first few days of life, the infant presented with anemia which was masked by concomitant maternal antepartum hemorrhage and neonatal intraventricular hemorrhage. SHL was suspected when the infant developed marked anemia, abdominal distension and hemoperitoneum on day 11 of life. Despite supportive transfusions, the infant's condition deteriorated and she died at 15 days of age. A large subcapsular hematoma of the liver was found at autopsy. We thus conclude that SHL should be considered in the normal course of differential diagnosis of acute blood loss in premature neonates.

Anemia↗

PubMed1993

Post-hybridization recovery of membrane filter-bound DNA for enzymatic DNA amplification.

We describe here a simple and rapid method for enzymatic DNA amplification using DNA template recovered from membrane filters previously used in hybridization analysis. This is done by first solubilizing membrane pieces carrying DNA of interest in dimethyl sulfoxide, followed by isopropanol precipitation and polymerase chain reaction amplification. The source of membrane-bound DNA successfully tested includes plasmid and human leukocyte DNA and DNA immobilized on bacterial colony filters and plaque lifts. The sensitivity of the procedure is such that DNA recovered from 0.5 microgram of filter-bound total human DNA was enough for PCR amplification of a 0.3-kb fragment. Our protocol will be useful for recycling of scarce DNA samples for cloning and sequencing purposes.

Biotechnology↗

PubMed1992

Genetic polymorphism and activities of human lung alcohol and aldehyde dehydrogenases: implications for ethanol metabolism and cytotoxicity.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) exhibit genetic polymorphism and tissue specificity. ADH and ALDH isozyme phenotypes from 39 surgical Chinese lung specimens were identified by agarose isoelectric focusing. The identity of the lung beta-ADHs was further demonstrated by their characteristic pH-activity profiles for ethanol oxidation, Km values for NAD and ethanol, and inhibition by 4-methylpyrazole or 1,10-phenanthroline. The beta 2 allele, coding for beta 2 polypeptide, was found to be predominant in the lung specimens studied. The ADH activities in the lungs with the homozygous phenotype ADH2 2-2 (exhibiting beta 2 beta 2) and ADH2 1-1 (exhibiting beta 1 beta 1) and the heterozygous phenotype ADH2 2-1 (exhibiting beta 2 beta 2, beta 2 beta 1, and beta 1 beta 1) were determined to be 999 +/- 77, 48 +/- 17, and 494 +/- 61 nmol/min/g tissue, respectively. Fifty-one percent of the specimens studied lacked the ALDH2 activity band on the isoelectric focusing gels. The activities in the lung tissues with the ALDH2-active phenotype and the inactive phenotype were determined to be 30 +/- 3 and 17 +/- 1 nmol/min/g tissue, respectively. These findings indicate that human pulmonary ethanol-metabolizing activities differ significantly with respect to genetic polymorphism at both the ADH2 and the ALDH2 loci. The results suggest that individuals with high Vmax beta 2-ADH and deficient in low-Km mitochondrial ALDH2, accounting for approximately 45% of the Chinese population, may end up with acetaldehyde accumulation during alcohol consumption, rendering them vulnerable to tissue injury caused by this highly reactive and toxic metabolite.

Adult↗