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Biomedical subjects

C H Cheng

Publications and source records attributed to C H Cheng.

At least 91 records · Page 5Linked to original sources
PubMed1997

Identification and characterization of growth hormone receptors in snakehead fish (Ophiocephalus argus cantor) liver.

The specific binding of 125I-labeled fish growth hormone (GH) to hepatic membranes prepared from several freshwater fish was assessed. A high level of growth hormone receptor (GHR) was detected on the hepatic membranes of the snakehead fish (Ophiocephalus argus Cantor). Scatchard analysis of the binding data showed a single class of high affinity binding site with a binding affinity (Ka) of 1.45 +/- 0.23 x 10(9) M-1 and a binding capacity (Bmax) of 198 +/- 57 fmol/mg protein. The binding was specific for fish GH and was saturable. In addition, the specific binding was temperature- and time-dependent, reaching a steady state after 16 hr of incubation at 25 degrees . The molecular weight of GHR as measured by Sephadex G-200 column chromatography and Western blot analysis using a monoclonal antibody (Mab263) against GHR was found to be 200-400 and 90-93 kDa, respectively. Two bands at 65 and 89 kDa were identified in ligand crosslinking studies of membrane receptors. A sensitive teleost GH radioreceptor assay (RRA) was developed, using recombinant fish GH and a membrane preparation from snakehead fish liver, capable of measuring bioactive GH in fish sera or other samples.

Animals↗
PubMed1997

In vitro and in vivo inhibitory actions of morin on rat brain phosphatidylinositolphosphate kinase activity.

Phosphatidylinositol-4,5-bisphosphate occupies a central role in signal transduction and in cellular transformation. Phosphatidylinositol-4,5-bisphosphate is produced by the enzymatic phosphorylation of phosphatidylinositol-4-phosphate by phosphatidylinositolphosphate kinase (EC 2.7.1.68). Inhibition of this enzyme might conceivably lowers the cellular pool of phosphatidylinositol-4,5-bisphosphate, thus constituting a feasible control point in regulating signal transduction and cellular transformation. Morin, a plant flavonoid, was demonstrated to exhibit in vitro inhibitory action on phosphatidylinositolphosphate kinase extracted from rat brain. This inhibition of enzymatic activity was found to be dose-dependent, with an IC50 value of approximately 10 microM morin. Lineweaver-Burk transformation of the inhibition data indicates that inhibition was competitive with respect to ATP. The Ki was calculated to be 5.15 x 10(-6) M. Inhibition was uncompetitive with respect to phosphatidylinositol-4-phosphate. The Ki was determined to be 0.94 x 10(-5) M. Administration of morin to rats led to a decrease in phosphatidylinositolphosphate kinase activity in brain extracts. This in vivo action of morin was found to be dose-dependent and time-dependent. These effects of morin on rat brain phosphatidylinositolphosphate kinase activity are discussed in relation to the other reported biological actions of this flavonoid.

Adenosine Triphosphate↗
PubMed1997

Genetic screening for Huntington's disease in Chinese patients with involuntary movements.

The diagnosis of Huntington's disease (HD) can be confirmed by detecting the expanded CAG repeat in the IT15 gene. Besides chorea, patients with HD may present with a variety of bizarre involuntary movements, resulting in confusion in making the diagnosis. Under such conditions, genetic analysis is the final confirmatory test. To determine if any patient with involuntary movements of undetermined etiology might be related to HD, we did genetic analysis on 22 patients and identified three with expanded CAG repeat. We could not obtain family history of HD in these patients due to adoption, early death of parents, or a vague history. All three patients were among the group with generalized chorea, but one had additional marked dystonic posturing. Together with four clinically recognizable HD patients, the relative frequency of HD among the 103 patients with choreiform movements in this hospital is 6.8%.

Adult↗
PubMed1997

Another simpler bypassing dialysate technique for measuring post-haemodialysis BUN.

BACKGROUND: The most popular method for estimating post-haemodialysis BUN is the low blood flow technique. The low blood flow technique with a blood flow of 50 ml/min for 3 min may encompass the first two phases of post-haemodialysis urea rebound by access and cardiopulmonary recirculations. Some patients may have risk of clotting in extracorporeal circuit while slowing blood flow. Therefore we proposed another simpler sampling technique for measuring post-haemodialysis BUN(C2). METHODS: In the present study, 28 long-term haemodialysis patients were divided into two groups. In group 1 (n = 15), C2 sample (C2-50) was collected immediately after blood flow was slowed down to 50 ml/min for another 3 min. Then blood flow was reset to 300 ml/min. Finally, C2 sample (C2B) was obtained from arterial port at the end of bypassing dialysate for another 3 min. In group 2 (n = 13), C2 sample (C2B) was obtained from arterial port at the end of bypassing dialysate for 3 min with a blood flow of 250 ml/min. Then dialysate was reset to original flow rate and C2 sample (C2-50) was collected soon after blood flow was slowed down to 50 ml/min for another 3 min. In the meantime, recirculation rate was also checked. RESULTS: The above two groups have similar results and there are no significant differences of post-haemodialysis BUN and calculated Kt/V between low blood flow technique and bypassing dialysate technique. CONCLUSION: The bypassing dialysate technique is another simpler and practical technique for the routine estimation of post-haemodialysis BUN.

Aged↗
PubMed1997

The functions of the first epidermal growth factor homology region of human protein C as revealed by a charge-to-alanine scanning mutagenesis investigation.

Variant proteins containing charge-to-alanine mutations of single amino acid residues and clusters of such groups contained in the epidermal growth factor 1 (EGF1) homology unit of human protein C (PC) have been accomplished, resulting in the following recombinant (r) mutant proteins: r-[E56A/H57A]PC; r-[H66A]PC; r-[D71A]PC; r-[D79A/R81A]PC; r-[E85A/R87A]PC; and r-[R91A/E92A]PC. Studies of the mutant proteins with a variety of Ca2+-dependent and Ca2+-independent monoclonal antibodies not only led to identification of the epitopes of these antibodies, but also confirmed the importance of D/beta-hydroxyaspartic acid (Hya)71 as one probable coordination site for Ca2+. Employing these antibodies, it was also revealed that Ca2+ binding to its site in the EGF1 region of PC did not influence Ca2+ binding or adoption of the Ca2+-dependent conformation of the gamma-carboxyglutamic acid domain of this same protein. In addition, the Ca2+-induced inhibition of PC activation by thrombin, and the kinetic constants for activation of PC by the thrombin/thrombomodulin complex, were only modestly affected by any of the mutations. The mutants r-[E56A/H57A]APC and r-[H66A]APC displayed at least 70% of wild type r-APC activity in a fVIII inactivation assay, while r-[D79A/R81A]APC, r-[E85A/R87A]APC and r-[R91A/E92A]APC possessed only approximately 40% activity in that same assay. The special role of D/Hya71 in this process was confirmed by showing that r-[D71A]APC was inactive in the fVIII-inactivation assay. These findings demonstrate that some of the charged residues of EGF1, most notably those in the carboxy-terminal region of this domain, participate as partial determinants of the anticoagulant activity of APC. Overall, with the exceptions noted, the data generally suggest that the charged residues of the EGF1 domain of PC, and the Ca2+ binding site contained within this module, are likely more involved with maintenance of the overall structural integrity of this module rather than with its direct functional interactions with effectors, activators, or substrates of PC and APC. Lastly, functional Ca2+ binding to the Gla domain of PC is not significantly influenced by the binding of Ca2+ to the EGF1 module.

Alanine↗
PubMed1997

Complications of membrane-filtration plasma exchange.

BACKGROUND: Plasma exchange (PE) has been extensively used to treat a variety of disease states in the past three decades. Although PE is commonly thought to be a relatively safe procedure, a number of unpleasant side effects may occur. To highlight the need for continuing quality assurance in providing PE service, a retrospective review of PE records over a 13-year period was undertaken. METHODS: From April 1983 to March 1996, 694 therapeutic PE procedures, membrane-filtration type, were performed on a total of 157 patients in this hospital. Plasmaflo op-05(L) (Asahi Japan) was used as the plasma separator and fresh frozen plasma of one plasma volume as replacement fluid. The PE sheets for all procedures were reviewed as were medical charts in order to evaluate clinical efficacy. RESULTS: Totally 694 PEs in 157 patients, 84 male and 73 females, ranging in age from 1 to 75 years (median, 35 years), were treated. Patients received a median of 4 treatments (range, 1 to 34). The most frequent indications were severe jaundice (41.4%), systemic lupus erythematosus (23.6%), and myasthenia gravis (15.3%). The overall effective rate was 40.8%, and was best in neurological diseases (91.4% effective). Complications of PE were noted during 36% of the procedures involving 59.2% of the patients treated. The most common adverse reactions were paresthesia (12.7%), chills (10.2%), urticaria (8.5%), chest pain (5.9%), nausea (2.9%) and dyspnea (2.0%). Less common complications included: catheter infection (0.3%), catheter oozing (1.2%), dizziness (1.3%), headache (0.4%), muscle cramps (1.3%), vomiting (0.4%), abdominal pain (0.9%), fever (0.3%), hypotension (1.3%), bleeding (0.4%), consciousness change (0.7%) and respiratory arrest (0.4%). These complications were classified as "mild" (23%), "moderate" (11.4%) and "severe" (1.6%). No deaths occurred within 24 hours after PE. CONCLUSIONS: Although the use of membrane-filtration PE represents a valuable and relatively safe therapy, some life-threatening reactions do occur.

Adolescent↗
PubMed1996

Modulatory effects of peroxovanadates on insulin receptor binding.

The insulin-mimetic effects exhibited by vanadate, hydrogen peroxide, and some peroxovanadates have recently been shown to occur, at least in part, through an activation of the insulin receptor tyrosine kinase activity. In this study, we examine the effects of these compounds on insulin receptor binding using receptor preparations from human placental membranes. Among the 16 vanadium(V)-peroxo complexes studied, the [VO(O2)2(bipy)]- ion, where bipy = 2,2'-bipyridine, was found to increase insulin receptor binding by 24%, whereas the [VO(O2)2(en)]- ion, where en = ethylenediamine, was found to reduce insulin receptor binding by about the same amount under steady-state conditions. Scatchard analysis of the binding data indicates that the observed effect of the [VO(O2)2(bipy)]- ion on insulin receptor binding is exerted mainly at the high-capacity low-affinity sites. Furthermore, this modulatory effect is reversible and requires a continuous presence of the compound. By perturbing the membrane environment of the insulin receptor, we have shown that an intact membrane structure is essential for an observable effect. The observed modulation of insulin receptor binding by peroxovanadates is interpreted in terms of a ternary complex model in which the peroxovanadate acts as an allosteric effector modulating the binding equilibrium between insulin and its receptor.

Humans↗
PubMed1996

Early clinical experience with the Multi-Link coronary stent.

The Multi-Link coronary stent (Advanced Cardiovascular Systems, Santa Clara, CA) is a balloon expandable stent carved from a stainless steel cylinder and is composed of 12 corrugated rings connected by multiple links. This design gives the stent great flexibility and conformity as well as radial strength. For the 3 month period from November 1995 to January 1996, all patients undergoing stent implantation in our institution were treated with this device, except for vessels smaller than 2.7 mm or larger than 3.7 mm in diameter, left main disease, or those who could not tolerate anticoagulation therapy. Forty patients, with a total of 42 arteries or 44 lesions, were treated with 56 stents, or 1.33 stents per artery. Clinical presentation included stable angina in 13 (32.5%), unstable angina in 24 (60%), acute myocardial infarction in 2 (5%), of whom 1 was in cardiogenic shock, and atypical symptoms with an abnormal thallium stress test in 1 (2.5%). According to the American College of Cardiology/ American Heart Association (ACC/AHA) classification, 8 lesions (18%) were type A, 14 (32%) type B1, 11 (25%) type B2, and 11 (25%) type C. Forty-three lesions (97.7%) were de novo and 1 (2.3%) restenotic. Stent delivery was successful in all patients. Complications included 1 balloon rupture at 7 atm but without sequelae, and 2 patients in whom the coronary guide wire became kinked and locked inside the catheter shaft of the stent delivery system but stent delivery was eventually successful. Mean diameter stenosis was reduced from 76 +/- 13% presenting to 2 +/- 9% poststenting and minimal lumen diameter increased from 0.87 +/- 0.38 to 2.82 +/- 0.34 mm. There were no acute-subacute stent thromboses, bleeding/vascular complications, or major cardiac events such as myocardial infarction, coronary artery bypass surgery, or death during a follow-up period of 2-5 months (mean 3.6 months). In conclusion, our early clinical experience with the Multi-Link stent is very encouraging, with a very high rate of successful delivery and minimal complications.

Adult↗
PubMed1996

Immobilized glucose-6-phosphate dehydrogenase as a substrate for solubilized epidermal growth factor receptor tyrosine kinase. A convenient microtiter plate assay system.

Based on our previously reported solution assay protocol, a solid-phase assay for the tyrosine kinase activity of the epidermal growth factor receptor has been developed. Glucose-6-phosphate dehydrogenase, immobilized noncovalently on microtiter plates, was used as the substrate in the solid-phase assay. Phosphorylation of the immobilized substrate takes place in the presence of ATP and a solubilized epidermal growth factor receptor preparation. After washing off the soluble reaction mixture, the phosphotyrosine-containing dehydrogenase produced on the well surface is quantitated by an ELISA method using a polyclonal antiphosphotyrosine antibody, a second antibody conjugated with horseradish peroxidase, and finally the o-phenylenediamine reaction. The absorbance at 492 nm developed in the wells is a measure of the kinase activity of the solubilized receptor preparation. Putative inhibitors of receptor kinase can be conveniently incorporated in this assay system to test for potential inhibitory activity. This assay, being rapid and convenient, is useful in drug screening programs where a high through-put rate is required.

Antibody Specificity↗
PubMed1996

Combined pCPA and muscarinic antagonist treatment produces a deficit in rat water maze acquisition.

A 3-day treatment with p-chlorophenylalanine (pCPA, 100 mg/kg/day) produced a significant decrease (63-89%) in 5-HT levels in both the hippocampus and the cortex of rats, while noradrenaline, adrenaline, and dopamine levels were unaffected. Treatment with pCPA alone did not affect the acquisition of a spatial learning task in the water maze. Treatment with low doses of either scopolamine (0.25 mg/kg) or atropine (10 mg/kg) was also insufficient to cause a significant impairment of water maze acquisition. However, a combined treatment of a 3-day pCPA regimen with the low dose of atropine or scopolamine produced a significant deficit in the acquisition of a water maze task.

Animals↗
PubMed1996

Phosphatidylinositol phosphate 5-kinase: purification and inhibition studies.

A membrane-associated phosphatidylinositol phosphate 5-kinase has been purified approximately 110,000-fold from sheep brains. The purification procedure involves: sodium chloride (1M) extraction of the membrane, 20-40% ammonium sulfate fractionation, phosphocellulose (P-11) chromatography, a second phosphocellulose chromatography, hydroxyapatite chromatography, heparin Sepharose chromatography, HPLC SP(SO3- polymer)-cation exchange chromatography, and HPLC gel filtration. The purified enzyme exhibited a final specific activity of 1750 nmole/min/mg of protein. The molecular mass of the enzyme was estimated to be approximately 60 kDa by SDS-PAGE and 130 kDa by HPLC gel filtration. Kinetic measurements showed that the apparent Km value of phosphatidylinositol phosphate 5-kinase for the utilization of ATP is 43 microM. The 2'(3')-0-(2,4,6-trinitrophenyl) derivative of ATP was found to be an inhibitor of the enzyme. The mode of inhibition is competitive, with a Ki value of 55 microM.

Adenosine Triphosphate↗
PubMed1996

Modulation of fibrin assembly and polymerization by the beta-amyloid of Alzheimer's disease.

Vascular deposition of amyloid beta protein (A beta P) is associated with recurrent intracerebral hemorrhages in certain disease states. Based upon these findings, we studied the effect of A beta P on fibrin (Fn) formation and fibrinolysis. We utilized electron microscopy and light scattering studies to examine alterations in the nature of the Fn clots obtained in the presence of the amyloid of Alzheimer's disease (AD), A beta P 1-40. Electron microscopic analysis revealed a network of FN and amyloid fibers formed in the presence of A beta P with significantly decreased lateral Fn-Fn interactions. Additional evidence for the assembly of an altered Fn matrix was obtained from kinetic assays that included fibrinogen (Fg), plasminogen, tissue-type plasminogen activator, and thrombin, in the presence of a fibril forming peptide derived from A beta P (A beta P 34-42). Turbidometric analysis of Fn clots showed that thrombin-treated Fg forms increasingly denser and more compact Fn fibers in the presence of increasing molar equivalents of A beta P 1-40. This conclusion was based upon the observed increases in the mass-to-length ratios, fiber radii, fiber densities, and the calculated number of Fn monomers per fiber cross-section. These results taken together suggest that amyloid forming peptides and proteins of AD significantly alter the nature of the Fn obtained in their presence.

Alzheimer Disease↗
PubMed1996

Rat proteinase-activated receptor-2 (PAR-2): cDNA sequence and activity of receptor-derived peptides in gastric and vascular tissue.

1. The biological activities of the proteinase-activated receptor number 2 (PAR-2)-derived peptides, SLIGRL (PP6) SLIGRL-NH2 (PP6-NH2) and SLIGR-NH2 (PP5-NH2) were measured in mouse and rat gastric longitudinal muscle (LM) tissue and in a rat aortic ring preparation and the actions of the PAR-2-derived peptides were compared with trypsin and with the actions of the thrombin receptor activating peptide, SFLLR-NH2 (TP5-NH2). 2. From a neonatal rat intestinal cDNA library, and from intestinal and kidney-derived cDNA, the coding region of the rat PAR-2 receptor was cloned and sequenced, thereby establishing its close sequence identity with the previously described mouse PAR-2 receptor; and this information, along with a reverse-transcriptase (RT) polymerase chain reaction (PCR) analysis of cDNA derived from gastric and aortic tissue was used to establish the concurrent presence of PAR-2 and thrombin receptor mRNA in both tissues. 3. In the mouse and rat gastric preparations, the PAR-2-derived polypeptides, PP6, PP6-HN2 and PP5-NH2 caused contractile responses that mimicked the contractile actions of low concentrations of trypsin (5 u/ml-1; 10 nM) and that were equivalent to contractions caused by TP5-NH2. 4. The cumulative exposure of the rat LM tissue to PP6-NH2 led to a desensitization of the contractile response to this polypeptide, but not to TP5-NH2 and vice versa, so as to indicate a lack of cross-desensitization between the receptors responsive to the PAR-2 and thrombin receptor-derived peptides. 5. In the rat gastric preparation, the potencies of the PAR-2-activating peptides were lower than the potency of TP5-NH2 (potency order: TP5-NH2 > > PP6-NH2 > or = PP6 > PP5-NH2); PP6 was a partial agonist in this preparation. 6. The contractile actions of PP6 and PP6-NH2 in the rat gastric preparation required the presence of extracellular calcium, were inhibited by nifedipine and were blocked by the cyclo-oxygenase inhibitor, indomethacin and by the tyrosine kinase inhibitor, genistein, but not by the kinase C inhibitor, GF109203X. The contractile responses were not blocked by atropine, chlorpheniramine, phenoxybenzamine, propranolol, ritanserin or tetrodotoxin. 7. In a precontracted rat aortic ring preparation, with an intact endothelium, all of the PAR-2-derived peptides caused a prompt relaxation response that was blocked by the nitric oxide synthase inhibitor, N omega-nitro-L-arginine-methyl ester (L-NAME) but not by D-NAME; in an endothelium-free preparation, which possessed mRNA for both the PAR-2 and thrombin receptors, the PAR-2-activating peptides caused neither a relaxation nor a contraction, in contrast with the contractile action of TP5-NH2. The relaxation response to PP6-NH2 was not blocked by atropine, chlorpheniramine, genistein, indomethacin, propranolol or ritanserin. 8. In the rat aortic preparation, the potencies of PP6, PP6-NH2 and PP5-NH2 were greater than those of the thrombin receptor activating peptide, TP5-NH2 (potency order: PP6-NH2 > or = PP6 > PP5-NH2 > TP5-NH2). 9. In the rat aortic preparation, the relaxant actions of the PAR-2-derived peptides were mimicked by trypsin, at concentrations (0.5-1 u ml-1; 1-2 nM) lower than those that can activate the thrombin receptor. 10. The bioassay data obtained with the PAR-2 peptides and with trypsin, along with the molecular cloning/RT-PCR analysis, point to the presence of functional PAR-2 receptors that can activate distinct responses in the gastric and vascular smooth muscle preparations. These responses were comparable to those resulting from thrombin receptor activation in the same tissues, so as to suggest that the receptor for the PAR-2-activating peptides may play a physiological role as far reaching as the one proposed for the thrombin receptor.

Animals↗
PubMed1996

Pulse spectrum analysis of hospital patients with possible liver problems.

Pulse diagnosis were performed on 85 patients who came to the hospital for liver and gall-bladder problems. Correlation between liver tests, which include T-Bil, D-Bil, SGOT, SGPT, ZTT, Alp, gamma-GT, Cho, Alb, and ultra sound scanning, and pulse diagnosis were analyzed. 77 out of 85 subjects showed abnormal liver tests. We used the following 5 criteria for pulse diagnosis as liver abnormality to test the correlation: (1) C1 > or = 3+ and C1 + C4 > or = 4+ or C1 + C6 > or = 4 (in intensity); (2) C1 < or = 3 (in intensity); (3) C6 > or = 3 and C1 + C6 > or = 4 (in intensity); (4) C6 < or = -2 (in intensity) and C6 < or = -2 (in the phase) and (5) C1 > or = 2 C3 < or = -2 (in intensity) or C3 < or = -2 (in the phase). For C1 (liver) every 5% above normal was given one "+," every 5% below normal was given one "-." For C3 (spleen), C4 (lung), C6 (gall-bladder), every 10% above normal was given one "+,", every 10% below normal was given one "-." For the phase, every 10% delay in the traveling speed was given one "-." When considering only the "+" and "-" states and neglecting the quantity of "+" and "-," there are 2(11) (from intensity) x 2(11) (from phase), which equal 2048 x 2048 possible states in the pulse analysis. We considered only 5 criteria for liver abnormality; the correlation was still very high, p < 0.0002, kappa = 0.64. It strongly suggests that meridian theory and pulse diagnosis have physiological and pathological importance.

Adolescent↗
PubMed1996

Implementation of ISO 9000 in the healthcare sector: a case study.

In order to compete at the international level, companies are beginning to recognize ISO 9000 registration as a virtual necessity. As a result, the number of ISO certifications issued in the U.S. and Canada tripled between 1992 and 1994. By means of a case study, this paper describes how a large healthcare manufacturing organization recently achieved its ISO 9001 certification. Specifically, the strategies and the process used by the organization in obtaining the registration is explained.

Certification↗
PubMed1996

Insulin-like growth factor IEa2 is the predominantly expressed form of IGF in common carp (Cyprinus carpio).

An insulin-like growth factor (IGF) complementary DNA (cDNA) was isolated from a liver cDNA library of adult common carp, Cyprinus carpio. The identity of this cDNA clone was confirmed by nucleotide sequence determination. Sequence comparison with other vertebrate and rainbow trout IGFs showed that this cDNA encodes a particular subtype of IGF-I, IGF-IEa2. A reverse transcription-polymerase chain reaction (RT-PCR) assay showed that this IGF-I is expressed mainly in the liver (hepatopancreas) of adult common carp. Analyses of 26 other cDNA clones isolated from the same library (using a probe carrying the conserved region of the common carp IGF-IEa2 cDNA clone) showed that these clones represent different insert sizes of the same IGF-IEa2. In conclusion, IGF-IEa2 is the predominantly expressed IGF in the liver of adult common carp.

Amino Acid Sequence↗