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Biomedical subjects

C C Chen

Publications and source records attributed to C C Chen.

At least 613 records · Page 34Linked to original sources
PubMed1986

The role of aldehyde dehydrogenase isozyme variance in alcohol sensitivity, drinking habits formation and the development of alcoholism in Japan, Taiwan and the Philippines.

It is known that aldehyde dehydrogenase (ALDH) responsible for metabolism of acetaldehyde deriving from ethanol has two distinct forms of isozymes: ALDH-I (low Km ALDH) and ALDH-II (high Km ALDH), and that many Orientals lack ALDH-I isozyme genetically. In the present study, the role of ALDH isozyme variance in the alcohol sensitivity, drinking habits formation and the development of alcoholism was investigated in Japan, Taiwan and the Phillipines. Isozyme analysis using isoelectric focusing of hair roots specimens from normal volunteers or schizophrenics revealed that about 42% of Japanese, 35% of Taiwanese and 12% of Phillipines were ALDH-I deficient. Questionnaire study of Japanese volunteers indicated that ALDH-I deficient individuals showed flushing, palpitation and other uncomfortable somatic signs, due to reduced metabolism of acetaldehyde, much more frequently than ALDH-I positive ones. Consequently, it occurred that only 19% (8/42) of ALDH-I deficient persons, in contrast to 49% (29/59) of ALDH-I positive ones, were drinking habitually. Patients with alcoholism showed much smaller percentages of ALDH-I deficiency: 4% (5/113) in Japan and 10% (3/29) in Taiwan, than those of control subjects. Summarizing these data, a hypothesis can be presented that genetically derived difference of ALDH activities is one of the determining factors in the sensitivity to alcohol, formation of drinking habits, and finally in the development of alcoholism, at least among Oriental peoples.

Alcoholism↗
PubMed1986

Congenital bile duct dilatation in children.

Fifteen children under the age of 15 were identified to have congenital dilatation of the biliary tree. Thirteen of them (87%) had dilatation of both intrahepatic and extrahepatic bile ducts, while two had extrahepatic biliary dilatation only. Visualization of both intrahepatic and extrahepatic biliary tree in small children before operation is possible by ultrasonography, endoscopic retrograde cholangio-pancreatography, or percutaneous transhepatic cholangiography. The advantage and disadvantage of those methods of examinations in children are discussed here. Dilatation of intrahepatic bile ducts is common in children with extrahepatic biliary dilatation. Assessment of both the intrahepatic and extrahepatic bile ducts bears a crucial role in the management of congenital biliary dilatation at operation and during the postoperative follow-up. Rouxen-Y hepaticojejunostomy with hepaticocutaneous arm was performed in our patients with satisfactory results. Residual intrahepatic stones could be removed through the hepaticocutaneous arm by choledochoscopy.

Adolescent↗
PubMed1986

Refractory cholangitis after Kasai's operation caused by candidiasis: a case report.

A case of biliary atresia treated by Kasai portoenterostomy was re-explored a year later for refractory cholangitis, which failed to respond to antibiotic treatment. Unexpectedly, the granulation tissue obstructing the porta hepatis contained pseudohyphae of Candida albicans. After curettage and Amphotericin B local irrigation, the patient became afebrile and anicteric.

Amphotericin B↗
PubMed1986

Solubilization and separation of the human erythrocyte D-glucose transporter covalently and noncovalently photoaffinity-labeled with [3H]cytochalasin B.

The D-glucose transporter in the human erythrocyte membranes was photoaffinity-labeled with [3H]cytochalasin B and solubilized with n-octyl beta-D-glucopyranoside (octyl glucoside). [3H]Cytochalasin B-bound proteins were further isolated by using Sephadex G-50 chromatography. The amount of [3H]cytochalasin B associated with the membrane proteins was approximately 10% of the total radioactivity in the octyl glucoside extract. The solubilized photoaffinity-labeled D-glucose transporter was isolated and found to consist of two major peaks by DEAE-Sephacel chromatography. The radioactivity of peak II was considerably greater than that of peak I. The incorporation of [3H]cytochalasin B into both peaks was blocked by the presence of D-glucose during photolysis. With preparative NaDod-SO4/polyacrylamide gel electrophoresis, the radioactivity of peak I could be released, but that of peak II remained with the D-glucose transporter. These results indicate that [3H]cytochalasin B was covalently bound to the D-glucose transporter only in peak II and that peak II could be generated by the photoaffinity labeling of peak I. However, the D-glucose transport activity was associated only with peak I. These findings suggest that the anionic domain of the D-glucose transporter becomes exposed because of conformational changes of the protein as a result of covalent binding with [3H]cytochalasin B by photoaffinity labeling.

Affinity Labels↗
PubMed1986

Human erythrocyte glucose transporter: normal asymmetric orientation and function in liposomes.

The transport function and orientation of the reconstituted human erythrocyte glucose transporter was studied with liposomes made with bovine brain lipid or Escherichia coli lipid. Reconstitution was achieved by a simple octyl glucoside dilution method. The reconstituted transporters with either lipid showed identical counterflow transport activity, the same response to various inhibitors, and characteristic cytochalasin B (CB) labeling. Functional location and purification of the glucose transporter was performed by using gel-permeation high-performance liquid chromatography with octyl glucoside-containing buffer. The reconstituted transport activity was associated only with band 4.5 protein (preactin) and not with band 3 protein. Both CB binding and transport function of the reconstituted transporters were resistant to trypsin but susceptible to chymotrypsin digestion. However, both trypsin and chymotrypsin treatment of unsealed ghosts completely eliminated the CB labeling and transport function of the glucose transporter. In our reconstitution system the glucose transporters maintained a normal asymmetrical (right-side-out) orientation and good transport function. A specific monoclonal antibody against the glucose transporter inhibited CB labeling of the transporters on unsealed ghosts. This was not found with the reconstituted system; however, after freeze-thawing there was a significant inhibition of CB binding by the antibody. These findings suggest that the CB-binding site of the reconstituted transporter is on the inner side of the proteoliposomes.

Binding Sites↗
PubMed1986

Diastolic 'locking' of the mitral valve: possible importance of diastolic myocardial properties.

The effects of pharmacologically induced changes in myocardial properties on diastolic mitral valve mechanics were studied in five open-chest dogs. After the induction of complete atrioventricular block, the dogs were subjected to a protocol of programmed pacing. During prolonged diastolic pauses, programmed atrial contractions were induced at progressively increasing coupling intervals. Echocardiographically determined mitral valve reopening time was established for each coupling interval in the control state as well as under the influence of calcium or verapamil. Compared with control, calcium caused an increase in myocardial tension from 23.8 +/- 3.0 to 30.0 +/- 4.6 g/cm2 (mean +/- SD, p less than .005) as well as an increase in mean septal contraction and relaxation velocities from 142 +/- 25.9 and 144 +/- 15.2 mm/sec to 188 +/- 21.7 and 174 +/- 19.5 mm/sec, respectively (each p less than .001). Conversely, verapamil caused a decrease in mean myocardial tension from 23.8 +/- 3.0 to 19.4 +/- 5.3 g/cm2 (p less than .001) and in mean septal contraction and relaxation velocities from 142 +/- 25.9 and 144 +/- 15.2 mm/sec to 112 +/- 32.7 and 112 +/- 21.6 mm/sec, respectively (each p less than .001). At every coupling interval, calcium significantly (p less than .01 to .001) prolonged, whereas verapamil significantly shortened (p less than .01 to .001), mitral reopening time compared with the control state. These pharmacologically induced changes in mitral valve mechanics occurred despite variations in left ventricular volume, as well as left ventricular and left atrial pressures that under normal conditions exert opposite effects on mitral valve mechanics.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Mode of inhibitory action of melittin on Na+-K+-ATPase activity of the rat synaptic membrane.

The effects of melittin from bee venom, cardiotoxin from Formosan cobra venom, and ouabain on Na+-K+-ATPase activity of the synaptic membrane isolated from rat cerebral cortex were studied. Melittin was the most potent in inhibiting Na+-K+-ATPase activity. Mg2+-ATPase was less susceptible than Na+-K+-ATPase to the inhibitory action of toxins. High K+ (30 mM) reversed the inhibitory action of melittin on Na+-K+-ATPase but did not affect that of cardiotoxin. A comparison between the effects of ouabain and melittin was studied, using double-reciprocal plots of Na+-K+-ATPase activity against K+. It was shown that both were competitive with K+ for binding to the K+ site. Moreover, a median-effect plot revealed that ouabain and melittin antagonized each other when inhibiting Na+-K+-ATPase. Phosphatidylcholine (PC) was the only one of the phospholipids tested capable of protecting Na+-K+-ATPase from the inhibitory action of melittin but not that of ouabain. However, the inhibitory action of cardiotoxin on this enzyme was decreased by phosphatidylserine and sphingomyelin, in addition to PC. All of these findings suggest that the melittin polypeptide potently inhibits Na+-K+-ATPase, possibly by binding to the K+ site.

Adenosine Triphosphatases↗
PubMed1985

Effect of different phospholipids on the reconstitution of two functions of the lactose carrier of Escherichia coli.

The lactose carrier was extracted from membranes of Escherichia coli and transport activity reconstituted in proteoliposomes containing different phospholipids. Two different assays for carrier activity were utilized: counterflow and membrane potential-driven uptake. Proteoliposomes composed of E. coli lipid or of 50% phosphatidylethanolamine--50% phosphatidylcholine showed very high transport activity with both assays. On the other hand, proteoliposomes containing asolectin, phosphatidylcholine or 25% cholesterol/75% phosphatidylcholine showed good counterflow activity but poor membrane potential-driven uptake. The discrepancy between the two types of transport activity in the latter group of three lipids is not due to leakiness to protons, size of proteoliposomes, or carrier protein content per proteoliposome. Apparently one function of the carrier molecule shows a broad tolerance for various phospholipids, while a second facet of the membrane protein activity requires very restricted lipid environment.

Biological Transport, Active↗
PubMed1985

Na+ (Li+)-proline cotransport in Escherichia coli.

Na+ and Li+ were found to stimulate the transport of L-proline by cells of Escherichia coli induced for proline utilization. The gene product of the put P gene is involved in the expression of this transport activity since the put P+ strains CSH 4 and WG 148 show activity and the put P- strain RM 2 fails to show this cation coupled transport. The addition of proline was found to stimulate the uptake of Li+ and of Na+. Attempts to demonstrate proline stimulated H+ uptake were unsuccessful. It is concluded that the proline carrier (coded by the put P gene) is responsible for Na+ (or Li+)-proline cotransport.

Biological Transport, Active↗