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Biomedical subjects

C M Chen

Publications and source records attributed to C M Chen.

At least 217 records · Page 12Linked to original sources
PubMed1992

The change of urinary 11-dehydro-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1 alpha in arteriogenic impotence.

Thromboxane A2 is a potent vasoconstrictor and a stimulus of platelet aggregation, which may contribute to hypercoagulability. The prostacyclin, prostaglandin I2, has exactly the opposite effect. Measurement of the major urinary metabolites, 11-dehydro-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1 alpha (prostaglandin F1 alpha) by radioimmunoassay can accurately reflect in vivo the biosynthesis of thromboxane A2 and prostaglandin I2, respectively. Group 1 consisted of 60 patients less than 50 years old. The mean urinary 11-dehydro-thromboxane B2 level of 3 patients with arteriogenic impotence was significantly greater than that of the 57 control volunteers: 2.66 +/- 0.65 versus 1.74 +/- 0.56 (plus or minus standard deviation) ng./mg. creatinine (p = 0.008). The prostaglandin F1 alpha levels for the patients and controls were 32.74 +/- 8.45 and 37.58 +/- 16.55 ng./mg. creatinine, respectively, which was not significantly different (p greater than 0.05). Group 2 consisted of 96 patients 50 years old or older. The 11-dehydro-thromboxane B2 concentration in the urine was 1.83 +/- 0.58, 2.54 +/- 1.12 and 1.91 +/- 0.73 ng./mg. creatinine in the 47 normal control volunteers, 20 patients with arteriogenic impotence and 29 with arteriogenic impotence plus intracavernous injection of 20 micrograms prostaglandin E1, respectively. The arteriogenic impotence group showed the significantly highest level among the 3 groups (p = 0.0025). Also, the urinary prostaglandin F1 alpha levels in these patients were 45.71 +/- 36.3, 57.71 +/- 35.53 and 59.30 +/- 45.08 ng./mg. creatinine, respectively, which was not significantly different (p greater than 0.05). For the 13 patients with arteriogenic impotence (group 3) we compared the urinary 11-dehydro-thromboxane B2 and prostaglandin F1 alpha levels before and after intracavernous injection of prostaglandin E1 by using a paired t test. The results showed that the change in 11-dehydro-thromboxane B2 levels was 2.78 +/- 1.09 versus 1.99 +/- 0.75 ng./mg. creatinine, which was significantly different (p = 0.005), whereas that for prostaglandin F1 alpha was 62.30 +/- 40.41 versus 58.86 +/- 44.26 ng./mg. creatinine, with no significant difference (p greater than 0.05). Our findings suggest that urinary 11-dehydro-thromboxane B2 may have an important role in the diagnosis and treatment of arteriogenic impotence.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Clinical trial of a low-temperature plastic anterior ankle foot orthosis.

The modification of a new design in orthosis usually has its clinical indication. In this study, a low-temperature thermoplastic ankle foot orthosis (AFO) was designed in anterior leaf type, called anterior AFO, to meet the need of indoor barefoot walking in Taiwan. It could be easily molded and remolded to fit the foot, as well as to adjust the position of the foot and ankle. Sixty-eight patients with acute hemiplegia were fitted with this anterior AFO during ambulation training: 46 had good fitting (67.6%), 15 had fair fitting (22.1%) and 7 had poor fitting (10.3%). Two patients were observed to have ankle clonus, and four patients experienced breakage or tear of the AFO within 4 wk. The gait characteristics were measured in six chronic hemiplegia patients to compare the effect of anterior AFO with posterior AFO (Teufel style). Their gait pattern did improve by AFO fitting, especially from the foot pressure distribution, but no significant difference between the two types of AFO was found.

Adult↗
PubMed1992

The traction angle and cervical intervertebral separation.

Seventeen normal young adults were evaluated for cervical intervertebral separation under different traction angles through motorized intermittent traction in the supine position. In all cases, the anterior and posterior intervertebral spaces were increased by traction at neutral position and in 30 degrees flexion, but not in 15 degrees extension. The effects of separation were 1) neutral position: anterior intervertebral separation C4-5 (12%) greater than C3-4 (8%), posterior intervertebral separation C6-7 (37%) greater than C3-4 (22%) greater than C4-5 (19%); and 2) 30 degrees flexion: anterior intervertebral separation C2-3 (21%) greater than C4-5 (16%) greater than C5-6 (15%) greater than C3-4 (10%), posterior intervertebral separation C6-7 (20%) greater than C5-6 (19%) greater than C4-5 (17%). There was a significant decrease in intervertebral separation posteriorly in extension traction, especially at C6-7 (-50%), C5-6 (-37%), C4-5 (-26%), and C3-4 (-14%). The separation of facet joint surfaces was found after traction at 15 degrees extension, but not in the neutral or flexion positions.

Adult↗
PubMed1992

Transcriptional regulation of nitrate reductase mRNA levels by cytokinin-abscisic Acid interactions in etiolated barley leaves.

To investigate the mechanisms by which the expression of a specific gene may be modulated by multiple hormones, the regulation of nitrate reductase (NR) mRNA levels by cytokinin and abscisic acid (ABA) was studied in etiolated barley (Hordeum vulgare L. cv Robust) leaves using a barley NR cDNA as a probe. Northern blot analyses of the levels of NR mRNA indicate that accumulation of the mRNA was enhanced by the cytokinin, benzyladenine (BA), and suppressed by ABA and that the hormonal effects on NR gene expression were responsive to dose concentrations (10(-7) to 10(-4) molar). The NR mRNA levels were influenced by the BA/ABA concentration ratios, and the inhibition of the NR transcript levels by ABA was not totally reversed by addition of equal concentrations (10(-7) to 10(-4) molar) of BA. Nuclear runoff transcription studies showed that the level of transcription was suppressed by ABA, and addition of an equal concentration of BA partially reversed the ABA action. Thus, the interaction of cytokinin and ABA on NR gene expression is, at least in part, at the level of transcription.

Journal Article↗
PubMed1992

Disposition of asarone after intravenous administration to rabbits assessed using HPLC.

A simple and sensitive high-performance liquid chromatography (HPLC) method for the determination of asarone in rabbit plasma has been developed. Up to 0.1 mL of plasma containing asarone was deproteinated by acetonitrile, which contained an internal standard (indomethacin). The supernatant was injected into a Nucleosil 7C18 column using acetonitrile-water-triethylamine (55:45:0.1 v/v, pH 5.4-5.5, adjusted with orthophosphoric acid) as the mobile phase and UV detection at 257 nm, followed by UV spectrum identification (between 200 and 380 nm) with a photodiode array detector. The method is rapid, easily reproduced, selective and sensitive. It was applied to pharmacokinetic studies of asarone in rabbit, after 5, 10, or 20 mg kg-1 intravenous administration. Rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve. The plasma disposition at each dose fitted well to a two-compartment open model and the terminal disposition became much slower as the dose was increased, suggesting a nonlinear dose-dependent plasma asarone disposition.

Allylbenzene Derivatives↗
PubMed1992

Hypothalamic amenorrhea in a case of mitochondrial encephalomyopathy.

A 26-year-old female with myoclonus epilepsy associated with ragged-red fibers is reported. Clinically, she had myoclonus epilepsy, cerebellar ataxia, a bilateral neurosensory type hearing loss, retinitis pigmentosa and short stature. She also presented with primary amenorrhea and poor development of secondary sexual characteristics. Endocrinologic studies revealed that hypothalamic dysfunction was the most plausible cause of her primary amenorrhea. Magnetic resonance imaging showed marked dilatation of the third ventricle indicating thalamic and hypothalamic degeneration. We conclude that hypothalamic dysfunction may be one of the characteristic features of mitochondrial encephalomyopathies.

Adult↗
PubMed1992

Expression of a partial synthetic human TNF cDNA in E. coli.

A recombinant human tumour necrosis factor (rhTNF) cDNA was constructed. The TNF gene was isolated from a human genomic gene library. There are four exons in the TNF gene. The fourth exon codes for 140 amino acids of the TNF matured protein which is composed of 157 amino acids. A major portion of the fourth exon was isolated and then ligated to a synthesized DNA fragment coding for the remaining amino acids. The partial synthetic hTNF (rhTNF) cDNA thus generated was subcloned into a vector and successfully expressed in E. coli. 5-1 fermentator was used to produce rhTNF. About 20 g (wet weight) of bacterial pellet per liter medium and 10(6)-10(7) units of cytotoxicity to L929 cells per milliliter medium were obtained. rhTNF was purified by HPLC and dried with a freeze dryer. rhTNF with a purity of about 95% in the form of white powder was obtained. The sequence of ten amino acids at the amino terminus of the rhTNF was determined. The result showed that it was identical with that of the natural human TNF.

Base Sequence↗
PubMed1992

Neonatal lupus erythematosus: a case report.

Neonatal lupus erythematosus is a syndrome characterized by congenital heart block and/or cutaneous lupus erythematosus in the presence of maternal autoantibodies. We report a female newborn with cutaneous lesions of the neonatal lupus erythematosus born to a clinically asymptomatic mother. She presented with erythematous maculopapules on the face, neck and upper trunk at birth. Complete blood cell count showed leukopenia and thrombocytopenia. Antinuclear antibodies, anti-Ro/SSA and anti-La/SSB antibodies were positive in the mother and infant. The skin lesions became annular, erythematous and slightly scaling three weeks later. A skin biopsy performed at seven weeks of age showed edema of the dermis and perivascular mononuclear cell infiltration. Immunofluorescent studies showed immune complex deposition of IgG an IgM in the basal zone of epidermis. She received supportive treatment and sun avoidance. Hematologic abnormalities recovered by nine weeks of age. Skin lesions faded gradually during the following four months, leaving residual hypopigmentation and telangiectasia.

Female↗
PubMed1991

Increased stability of nucleolin in proliferating cells by inhibition of its self-cleaving activity.

Nucleolin is the major nucleolar phosphoprotein of exponentially growing eukaryotic cells and is presumably involved in pre-rRNA transcription and ribosome biogenesis. Monoclonal antibodies against nucleolin were selected by a differential dot-immunobinding assay. Nucleolin expression during T lymphocyte activation was monitored by the specific antibody. Results showed that nucleolin fluctuated in parallel to DNA synthesis. The intact 105-kDa nucleolin molecule was the major species in actively dividing cells, whereas the degraded forms were relatively abundant in nondividing cells. These results imply that stability of nucleolin molecule is cell proliferation-dependent. When affinity purified nucleolin containing undetectable contaminants was incubated at 37 degrees C, the majority of 105-kDa nucleolin was cleaved by 6 h and completely degraded within 24 h. This purified nucleolin was further separated from possible copurified protease, if any, on a reducing sodium dodecyl sulfate-polyacrylamide gel. After renaturation, the 105-kDa nucleolin immobilized in the gel was also cleaved at 37 degrees C. These data have confirmed that nucleolin protein autocatalyzes its own degradation. The self-cleaving activity of nucleolin was inhibited by nuclear extracts prepared from proliferating cells. Apparently, a proteolytic inhibitor(s) in the nuclei of proliferating cells stabilized the nucleolin molecule. It provides an unique regulatory mechanism for nucleolin expression.

Antibodies, Monoclonal↗
PubMed1991

Human and Escherichia coli cyclophilins: sensitivity to inhibition by the immunosuppressant cyclosporin A correlates with a specific tryptophan residue.

The human T-cell protein cyclophilin shows high affinity for and is the proposed target of the major immunosuppressant drug cyclosporin A (CsA). Cyclophilin also has peptidyl prolyl cis-trans isomerase activity that is inhibited by CsA with an IC50 of 6 nM, while by contrast a homologous PPIase from Escherichia coli has been found to be much less sensitive to CsA, shown here to be 500-fold less potent at an IC50 of 3000 nM. This E. coli rotamase lacks the single highly conserved tryptophan residue of eukaryotic cyclophilins, and we show here that mutation of the natural F112 to W112 enhances E. coli rotamase susceptibility to CsA inhibition by 23-fold. Correspondingly, the human W121 mutations to F121 or A121 yield cyclophilins with 75- and 200-fold decreased sensitivity to CsA, while kcat/Km values of rotamase activity in a tetrapeptide assay drop only 2- and 13-fold, respectively. This complementary gain and loss of CsA sensitivity to mutation to or from tryptophan validate the indole side chain as a major determinant in immunosuppressant drug recognition and the separation of PPIase catalytic efficiency from CsA affinity.

Amino Acid Isomerases↗
PubMed1991

Induction of heat-shock response and alterations of protein phosphorylation by a novel topoisomerase II inhibitor, withangulatin A, in 9L rat brain tumor cells.

Withangulatin A is a newly identified in vitro topoisomerase II inhibitor isolated from the Chinese antitumor herb Physalis angulata. In vivo, it was found to be cytotoxic, capable of suppressing general protein synthesis and of inducing the synthesis of a small set of proteins including those generated by heat-shock treatment. The 70 kDa protein generated by withangulatin A was unequivocally identified as the heat-shock protein 70 (HSP70) since both proteins migrated to the same position on two-dimensional polyacrylamide gels, could be recognized by a monoclonal antibody to human HSP70, and exhibited identical peptide maps. The induction of protein synthesis by withangulatin A was regulated at the transcriptional level since it was aborted in cells pre-treated with actinomycin D. However, the initiation of this process did not require de novo protein synthesis since it was not affected by cycloheximide. Other cellular effect of withangulatin A was alterations of protein phosphorylation including an enhancement of phosphorylation of a 65 kDa protein which was also detected in the heat-shocked cells. Moreover, this process was observed within 7.5 min after the initial heat treatment which is much faster than the onset of HSP synthesis. Therefore, increased phosphorylation of the 65 kDa protein may represent one of the earliest signals generated by both heat-shock and withangluatin A and may be involved in the upstream regulation of heat-shock response in cells.

Animals↗
PubMed1991

3,4-Dihydroxyxanthone dioxygenase from Arthrobacter sp. strain GFB100.

Bacterial extradiol ring-fission dioxygenases play a critical role in the transformation of multiring aromatic compounds to more readily biodegradable aromatic or aliphatic intermediates. Arthrobacter sp. strain GFB100 utilizes an extradiol meta-fission dioxygenase, 3,4-dihydroxyxanthone dioxygenase (DHXD), in the catabolism of the three-ring oxygen heterocyclic compound xanthone. In this paper, we show that DHXD is a cytosolic enzyme, induced by growth on xanthone and maximally expressed during the stationary phase of growth. In addition, we characterize the DHXD activity in terms of its basic enzymological properties. 1,10-Phenanthroline and H2O2 treatments eliminated DHXD activity, indicating that the enzyme required Fe2+ ions for activity. Other divalent cations were either inhibitory or had no effect on activity. DHXD had a temperature optimum of 30 degrees C and a pH optimum of 7.0. DHXD followed typical saturation kinetics and had an apparent Km of 10 microM for 3,4-dihydroxyxanthone. The dye celestine blue served as a noncompetitive DHXD inhibitor (Ki, 5 microM). Several other structural analogs served neither as substrates nor inhibitors. DHXD was thermally labile at temperatures above 40 degrees C. The half-life for thermal DHXD inactivation was 5 min at 40 degrees C. DHXD activity was completely stable through one freeze-thaw cycle, and about 80% of the DHXD activity remained after 2 days of incubation at 0 degree C. The apparent tight binding of the Fe2+ cofactor to DHXD may be a factor contributing to the stability of this extradiol dioxygenase when it is stored.

Arthrobacter↗
PubMed1991

Molecular location of a species-specific epitope on the hamster scrapie agent protein.

Scrapie is a transmissible neurodegenerative disease of sheep and goats. An abnormal host protein, Sp33-37, is the major protein component of the scrapie agent and the only known disease- or agent-specific macromolecule. Two monoclonal antibodies (MAbs), 4H8 (immunoglobulin G2b [IgG2b]) and 6B11 (IgG1), produced by immunizing mice with the intact hamster 263K scrapie agent protein, Sp33-37Ha, were found to have species specificity similar to that reported previously for MAb 3F4 (IgG2a), which was produced by using PrP-27-30 as the immunogen (R. J. Kascsak, R. Rubenstein, P. A. Merz, M. Tonna-DeMasi, R. Fersko, R. I. Carp, H. M. Wisniewski, and H. Diringer, J. Virol. 61:3688-3693, 1987). These antibodies all bound to Sp33-37 derived from hamster but not from mouse cells. Competitive binding assays demonstrated that all three MAbs bound to the same or overlapping sites on Sp33-37Ha. The molecular location of the epitope for these antibodies was determined to within 10 residues by using an antigen competition enzyme-linked immunosorbent assay in which synthetic peptides spanning Sp33-37Ha residues 79 to 93 or 84 to 93 specifically inhibited binding of these antibodies to plates coated with purified Sp33-37Ha. A synthetic peptide with the mouse-specific sequence (83 to 92) that differed from the hamster sequence by substitution at two positions (MetHa-87----LeuMo-86 and MetHa-90----ValMo-89) did not inhibit antibody binding to Sp33-37Ha. MAb 3F4 binding to hamster Sp33-37 was eliminated by chemical modification of Sp33-37Ha with diethylpyrocarbonate or succinic anhydride and by cleavage with CNBr or trypsin. The effect of diethylpyrocarbonate on MAb 3F4 binding was not reversed by hydroxylamine treatment. MAb 3F4 binding was not affected by prolonged exposure of Sp33-37Ha to 70% formic acid or by boiling in sodium dodecyl sulfate. We conclude that the epitope for these MAbs is a linear determinant that includes Met-87, Lys-88, and Met-90 and that Met-90 is probably the major species-specific determinant.

Amino Acid Sequence↗
PubMed1991

Immunoglobulin and renal abnormalities in Dahl genetically hypertensive rat.

The Dahl salt-sensitive rat (DS) is a model of genetically determined arterial hypertension exacerbated by dietary salt. We report two additional abnormalities of DS rats, which are both genetically determined and enhanced by salt: 1) immunoglobulin disorders and 2) renal dysfunctions. These abnormalities precede and are not the result of the arterial hypertension. In young, prehypertensive DS rats the plasma and tissue concentrations of immunoglobulin (Ig) G, but not of IgM or IgA, are decreased compared with those of the salt-resistant strain (DR). A high-salt diet (8.0% NaCl) decreases the plasma and tissue IgG levels of DS but not of DR rats. Reduction of IgG in the DS strain results from both decreased synthesis and increased urinary excretion. Renal dysfunction in young, prehypertensive DS animals is manifested by increased excretion of high molecular weight proteins, including albumin, IgG, IgA, and IgM. The high-salt diet increases the urinary excretion of these proteins within 1-2 days, and the effect is much greater in DS compared with DR rats. The urinary excretion of IgG is selectively increased relative to immunoglobulin light chains, IgA and IgM in DS compared with DR animals. The present studies provide new markers characteristic of the DS phenotype and pose the issue of possible genetic or functional interrelationships among the salt-sensitive hypertension, immunoglobulin disorders, and renal dysfunctions.

Albuminuria↗
PubMed1991

[Candida arthritis: report of two cases].

Candida arthritis is extremely rare. However, there has been a steady increase in the incidence of candida arthritis during the last decade because of increasing candida infections in immunocompromised hosts, drug addicts, premature babies, and those who have received prosthetic joint operations or intraarticular injections of steroids. We report herein two cases of candida arthritis: a 27-year-old man with aplastic anemia and transfusional hemosiderosis, and a 60-year-old man with osteoarthritis who received repeated intra-articular injections of steroids. Definite diagnoses were made after repeated smear examinations of synovial fluids. In the first case, candida arthritis occurred about 2 weeks after an antecedent candidemia. Although the arthritis relapsed once due to inadequate antifungal treatment, it was finally successfully treated with systemic amphotericin B, oral ketoconazole and surgical drainage of the synovial fluid. In the second case, it took several months to make the diagnosis. The patient was also treated with amphotericin B, ketoconazole, and surgery with a satisfactory outcome. We conclude that since candida arthritis is a slow, less destructive joint infection, it can almost always be resolved. Also, late orthopedic complications can be avoided by early diagnosis and prompt treatment, including aggressive antifungal therapy, adequate drainage and necessary surgical intervention.

Adult↗
PubMed1990

Mutagenesis of a nucleotide-binding site of an anion-translocating ATPase.

The ars operon of the conjugative R-factor R773 confers resistance to arsenicals by coding for an anion pump for extrusion of arsenicals from cells of Escherichia coli. The operon encodes three structural genes arsA, arsB, and arsC. The anion pump requires only two polypeptides, the ArsA and ArsB proteins. Purified ArsA protein exhibits oxyanion-stimulated ATPase activity and was demonstrated to bind ATP by photoaffinity labeling with [alpha-32P]ATP. Analysis of the amino acid sequence deduced from the nucleotide sequence of the arsA gene suggests that the ArsA protein contains two potential nucleotide binding folds, one in the N-terminal half and one in the C-terminal half of the protein. A combination of site-directed and bisulfite mutagenesis was used to alter the glycine-rich region of the N-terminal putative nucleotide-binding sequence G15KGGVGKTS23. Four mutant proteins (G18----D, G18----R, G20----S, and T22----I) were analyzed. Strains bearing the mutated plasmids were all arsenite sensitive and were unable to extrude arsenite. Each purified mutant protein lacked oxyanion-stimulated ATPase activity and ATP binding. These results suggest that the N-terminal sequence is part of a nucleotide-binding domain required for catalysis.

Adenosine Triphosphatases↗
PubMed1990

Mandibular fractures in children-immediate reduction and fixation with orthodontic resin.

Mandibular fractures are not common in children. In Chang Gung Memorial Hospital from 1983 to 1987, we had 354 mandibular fractures but only 12 cases happened to children under 10 years old. Mandibular fractures in children under 10 years cannot be treated in the same way as patient with permanent teeth since possibly neither intermaxillary, nor interosseous fixation can be applied. Complication have been observed in 3 (25%) of these 12 patients, including malocclusion, infection and open bite. In 1988, orthodontic resin was adopted as the fixation material after immediate reduction in three cases. There is no complication and the patients have had a better postinjury quality of life compared with those patients treated from 1983 to 1987. The importance of immediate reduction for mandibular fracture in children and the application of resin cap splint are stressed.

Child↗