Search PubMed⌕ Search

Biomedical subjects

S L Chen

Publications and source records attributed to S L Chen.

At least 163 records · Page 9Linked to original sources
PubMed1991

[Dynamic investigation of antithrombin III in the plasma of patients with acute myocardial infarction].

Antithrombin III level in the plasma of patients with AMI was determined dynamically by using the methods of chromogenic substrate and rocket electrophoresis. Meanwhile, plasma specimens of 40 normal subjects were examined with the same method. The results showed that the AT III level in AMI patients was much lower than that in normal controls at the first and third day after infarction. The level was also significantly lower than that at the 7th, 14th and 21st day after the onset of the disease. It revealed that there was a hypercoagulative state in patients within the first three days of infarction. The AT III level in patients who died within ten days was much lower than that in the survivor group, P less than 0.01. The authors concluded that a patient may be in a severe condition when their plasma AT III levels decrease apparently and persistently.

Adult↗
PubMed1990

Chlorobutanol, a preservative of desmopressin, inhibits human platelet aggregation and release in vitro.

Therapeutic preparations of desmopressin for parenteral use contain the preservative chlorobutanol (5 mg/ml). We show here that chlorobutanol is a potent inhibitor of platelet aggregation and release. It exhibited a significant inhibitory activity toward several aggregation inducers in a concentration- and time-dependent manner. Thromboxane B2 formation, ATP release, and elevation of cytosolic free calcium caused by collagen, ADP, epinephrine, arachidonic acid and thrombin respectively were markedly inhibited by chlorobutanol. Chlorobutanol had no effect on elastase-treated platelets and its antiplatelet effect could be reversed. It is concluded that the antiplatelet effect of chlorobutanol is mainly due to its inhibition on the arachidonic acid pathway but it is unlikely to have a nonspecific toxic effect. This antiplatelet effect of chlorobutanol suggests that desmopressin, when administered for improving hemostasis, should not contain chlorobutanol as a preservative.

Adenosine Triphosphate↗
PubMed1990

Daurisoline derivatives inhibit the ability of calmodulin to stimulate cyclic nucleotide phosphodiesterase activity.

Daurisoline alkaloid derivatives were found to be potent calmodulin (CaM) antagonists. The ability of daurisoline derivatives to attenuate the stimulatory effect on calmodulin activated cyclic nucleotides phosphodiesterase (CaM-PDE) was studied. These compounds did not inhibit the basal activity of this enzyme. The hydrophobicity of these compounds was related to their inhibitory potency. It is suggested that such drugs bind directly to calmodulin in a Ca2(+)-dependent fashion, as indicated by their ability to change calmodulin fluorescence.

Alkaloids↗
PubMed1990

Effect of insulin pump therapy on blood pressure and the renin-angiotensin system of diabetic rats.

Insulin therapy, administered by continuous subcutaneous infusion with osmotic pumps over a 28 day period at doses of 2.5 and 5.0 units/day, resulted in a statistically significant increase in body weight of diabetic rats. The concentration of blood glucose was reduced by 68% to 109 mg/dl blood sugar by the higher dose of insulin and only partial control of diabetes was achieved by the lower dose (185 mg/dl blood sugar, -39%). Blood pressure was normalized by both doses of insulin. Elevated serum angiotensin converting enzyme activity and plasma renin activity, expressed as generated angiotensin I, were unaffected by the lower dose of insulin, but were reduced by 26% and 40%, respectively at the higher dose. These data suggest that elevated serum ACE and plasma renin activity, commonly found in the streptozotocin-diabetic rat, may not be primarily responsible for hypertension in this model.

Animals↗
PubMed1990

Transforming activity of E5a protein of human papillomavirus type 6 in NIH 3T3 and C127 cells.

Human papillomavirus type 6 (HPV-6) is the etiologic agent of genital warts and recurrent respiratory papillomatosis. We are investigating the mechanism by which this virus stimulates cell proliferation during infection. In this paper, we report that the E5a gene of HPV-6c, an independent isolate of HPV-11, is capable of transforming NIH 3T3 cells. The E5a open reading frame (ORF) was expressed under the control of the mouse metallothionein promoter in the expression vector pMt.neo.1, which also contains the gene for G418 resistance. Transfected cells were selected for G418 resistance and analyzed for a transformed phenotype. The transformed NIH 3T3 cells overgrew a confluent monolayer, had an accelerated generation time, and were anchorage independent. In contrast, E5a did not induce foci in C127 cells, but C127 cells expressing E5a did form small colonies in suspension. The presence of the 12-kilodalton E5a gene product in the transformed NIH 3T3 cells was shown by immunoprecipitation and was localized predominantly to nuclei by an immunoperoxidase assay. A mutation in the E5a ORF was engineered to terminate translation. This mutant was defective for transformation, demonstrating that translation of the E5a ORF is required for biological activity. This is the first demonstration of a transforming oncogene in HPV-6, and the differential activity of E5a in these two cell lines should facilitate future investigations on the mechanism of transformation.

Amino Acid Sequence↗
PubMed1990

[The clinical significance of antibodies to SM, RNP and SSR polypeptides detected by immunoblotting technique].

Using immunoblotting technique (IBT) antibodies to Sm, RNP and SSB polypeptides we detected in 173 patients with different rheumatic diseases. It was found that antibodies to Sm polypeptides with molecular weights of 28K(B) and 13.5K(D) could be detected almost only in SLE (34.0% and 30.0% respectively). The positive rates of anti-28K and anti-13.5K polypeptides in SLE detected by IBT were significantly higher than those of anti-Sm by counterimmunoelectrophoresis (12.0%) (P less than 0.05). The antibodies to SSB polypeptides with molecular weights of 48K and 43.41K could be detected mainly in Sjogren's syndrome (70.0% and 65.0% respectively) and the antibodies to RNP polypeptides with molecular weights of 68K, 32K(A) and 29K (B') mainly in MCTD (82.6% 100% and 34.8% respectively) (P less than 0.001). It was reported by Pettersson that anti-68K polypeptide had high specificity for the diagnosis of MCTD. But our data showed that the anti-68K polypeptide could also be detected in SLE(26.0%) and PSS(15.0%) and was not so specific for MCTD.

Antibodies, Antinuclear↗
PubMed1990

[A study on transovarial transmission of dengue type 1 virus in Aedes aegypti].

The main purpose of this study is to determine the possibility of transovarial transmission of dengue type 1 virus, which was isolated from the serum of a patient with dengue fever during the 1987 dengue epidemic in southern Taiwan, in Aedes aegypti of Kaohsiung strain (KH). Parent female mosquitoes were inoculated with dengue 1 virus by intrathoracic inoculation technique. The F1 offspring adults collected from three sequential ovarian cycles were pooled to become 51, 13 and 14 pools, respectively. All pools were individually inoculated into C6/36 cells and then were detected by direct immunofluorescence antibody technique. Ten, five and three pools, respectively, among these three ovarian cycles turned out to be positive. It revealed that the minimum infection rates (MIR), were 1:254.6 (2,546 mosquitoes), 1:133.6 (668 mosquitoes) and 1:238 (714 mosquitoes), respectively. Meanwhile, the estimated filial infection rates were calculated to be 0.44%, 0.97% and 0.48%, respectively. Since viral antigen has been detected in the tissue of maturing eggs within ovarioles, the results exhibited the possibility that dengue type 1 virus can be transovarially transmitted to the next generation.

Aedes↗
PubMed1990

Correlations of blood lipids and lipoproteins with coronary artery disease documented by angiography.

A study of the relationships between serum TC, TG and HDL.C and selective coronary arteriography was carried out on 117 patients who were divided into groups according to the extent of artery stenosis. Normal control group consisted of 153 healthy subjects. There were no statistical differences in TC, TG, HDL.C, LDL.C, TC/HDL.C, LDL.C/HDL.C and TC-HDL.C/HDL.C between normal control group and the group with normal coronary arteriogram. LDL.C, TC/HDL.C, LDL.C/HDL.C, TC HDL.C/HDL.C rose and HDL.C decreased as the degree of coronary artery stenosis and the extent of stenosis increased, besides the medium and severe stenosis group. Analyses based on the correlation coefficients indicate that 3 compound indexes (TC-HDL.C/HDL.C, TC-HDL.C, LDL.C/HDL.C) are better in assessing CAD than single index such as LDL.C, HDL.C and TC. The results of our study showed that the 3 compound indexes might be regarded as important risk factors for CAD.

Adult↗
PubMed1990

[Effect of nitroglycerin on coronary circulation of the ischemic region in dogs].

The purpose of this study was to define the effects of nitroglycerin on coronary circulation in ischemic region. In 18 open chest dogs, a critical stenosis of the left anterior descending coronary artery was produced by an external micrometer constrictor. Intracoronary infusion of nitroglycerin 0.5 micrograms/kg. min-1 increased coronary blood flow (CBF) and decreased distal coronary pressure (DCP), total coronary artery resistance (RT), small coronary artery resistance (RS); but did not affect mean aortic pressure, heart rate and large coronary artery resistance (RL). The whole blood viscosity in coronary vein was reduced. Intracoronary infusion of nitroglycerin 1 microgram/kg.min-1, CBF increased and RT, RL, RS, DCP decreased during the first 5min. Then the CBF decreased, RT and RL increased. These were associated with a decrease in DCP and an increase in whole blood viscosity. A passive narrowing of the stenotic area was observed. These results indicate that nitroglycerin has two effects on coronary circulation, it can increase CBF and decrease coronary artery resistance in relieving myocardial ischemia; it can also decrease CBF and cause passive narrowing of coronary artery in worsing myocardial ischemia. The beneficial or harmful effect of nitroglycerin may depend on its doses and DCP.

Animals↗
PubMed1990

[Effect of nicorandil on coronary circulation in ischemic region].

To clarify the role of nicorandil (Nic) in relieving myocardial ischemia, the effects of Nic in canine models of coronary arterial stenosis were studied. During stenosis of the anterior descending coronary artery by an external micrometer constrictor, intracoronary infusion of Nic 1, 5 micrograms/(kg.min) increased coronary blood flow and decreased distal coronary pressure, total coronary arterial resistance and small coronary arterial resistance; but did not affect mean aortic pressure, heart rate and large coronary arterial resistance. Whole blood viscosity, plasma viscosity and hematocrit in coronary vein after intracoronary infusion of Nic were reduced. The results intravenous infusion of Nic were similar to those of intracoronary infusion. These results indicate that Nic is capable of increasing coronary blood flow, alleviating myocardial ischemia due to direct dilatation of coronary artery and reduction of blood viscosity in ischemic region.

Animals↗
PubMed1990

[Effect of Salvia miltiorrhiza on the left ventricular diastolic function in coronary artery stenosis].

In 24 open-chest mongrel dogs, coronary artery critical stenosis were produced by a micrometer constriction on left circumflex coronary artery. It was reduction about 87% in lumen area. CBF, -Vce, -dp/dt max were decreased, T was increased (P less than 0.01). 15 minutes after stenosis, the Salvia miltiorrhiza injection was injected into left atrium. CBF, -dp/dt max, -Vce were increased and T was decreased after the injection of Salvia miltiorrhiza. Moreover, the change of CBF was the earliest. The results proved that the Salvia miltiorrhiza could improve the left ventricular diastolic function in coronary artery stenosis.

Animals↗
PubMed1990

Macromolecular synthesis in the isolated rat myointima in vitro.

The myointima, which forms within the lumen of the carotid artery of the rat in response to the removal of the endothelium by a balloon catheter, could be extruded from the vessel as early as 6 days after denudation. The mean concentration of DNA in the isolated myointima increased as the myointima grew in vivo until 12 to 14 days after denudation, when the arterial lumen was filled with the myointima; thereafter the mean concentration of DNA declined. DNA and protein synthesis, incorporation of 3H-glucosamine and 3H-fucose into macromolecules, occurred in the myointima during incubation in vitro in the absence of fetal bovine serum, and with the exception of 3H-glucosamine, failed to be stimulated by it. These data indicate that the cells of the intact myointima do not require exogenous macromolecular growth factors for the synthesis of macromolecules in vitro.

Animals↗
PubMed1989

Detection by antibody probes of human papillomavirus type 6 E5 proteins in respiratory papillomata.

We have demonstrated the expression of proteins arising from the E5a and E5b open reading frames (ORFs) of human papillomavirus type 6c (HPV-6c) in respiratory tract papillomata. Recombinant plasmids were constructed to express the ORFs in the bacterial vectors pATH and pRIT2T. Fusion proteins were purified and injected into rabbits to produce polyclonal antibodies. Characterized antibodies generated against these fusion proteins were used in immunoperoxidase assays to identify the presence and distribution of HPV-6 E5 proteins in biopsy specimens of respiratory tract papillomata. The results showed that the E5a and E5b proteins were distributed throughout the thickness of the epithelium in the papillomata but not in the basal layer. The proteins were found in nuclei and in the cytoplasm of koilocytotic cells. Positive reactivity with a similar distribution in the epithelium and subcellular location was obtained in papillomata induced by other HPV-6 subtypes. This cross-reactivity was not unexpected, since nucleotide and amino acid (aa) sequence comparisons between HPV-6c and -6e demonstrated 79% sequence identity with 15 aa substitutions in the 91 aa of E5a. The E5b ORF of HPV-6c has the potential to encode a protein of 74 aa that differed at 28 positions compared with the 72 aa of HPV-6e.

Amino Acid Sequence↗
PubMed1989

Structural analysis of human papillomavirus type 6c isolates from condyloma acuminatum and juvenile-onset and adult-onset laryngeal papillomata.

The human papillomavirus type 6c (HPV-6c) genome was molecularly cloned from biopsy specimens of a juvenile-onset and an adult-onset respiratory-tract papillomata and a condyloma acuminatum of the cervix. To determine if the genital-tract isolate and respiratory-tract isolates contain divergent sequences that may account for a difference in tissue trophism or for a difference in the age of onset of the disease, fine-structure mapping, heteroduplex analysis by electron microscopy, and nucleotide sequencing were used to examine the sequence relationship among these HPV-6c isolates. No differences were found in the digestion patterns with 23 restriction enzymes. Heteroduplex analysis among the three genomes demonstrated that they were colinear without apparent deletions or rearrangements and had greater than 90% sequence identity. In heteroduplex analyses with a different subtype (HPV-6e) that was molecularly cloned from a genital wart, the genomes were colinear with greater than 90% sequence identity over 90% of their length. The most divergent region had 75-80% sequence identity and was localized to the part of the genome containing the E5a and E5b open reading frames (ORFs). Comparison of the sequence of 1430 nucleotides in this region for two of the HPV-6c isolates did not identify any differences between them. Comparison with the published sequences of HPV-6b identified deletions/insertions and base changes with approximately 75% sequence identity, and comparison with HPV-11 identified only six base changes. Conservation of sequences in the E4-E5 region and similarity in the restriction enzyme maps demonstrated that HPV-6c and HPV-11 are independent isolates of the same HPV-6 subtype.

Base Sequence↗
PubMed1989

Blood pressure reduction in hypertensive-diabetic rats by the somatostatin analog MK-678.

A hypotensive effect of an orally-administered cyclopeptide somatostatin analog, MK-678, has been demonstrated in a hypertensive diabetic rat model. Sustained blood pressure reduction failed to occur when the drug was administered to the spontaneously hypertensive rat. The mechanism of hypotension appears independent of effects on a variety of hormones including insulin, glucagon, growth hormone, and components of the renin-angiotensin system including renin activity, plasma angiotensin converting enzyme, and aldosterone.

Animals↗
PubMed1989

Recording of the electrocardiogram from the sinus node and direct measurement of the sinuatrial conduction time in children.

Using a simple technique, the electrocardiogram from the sinus node, which had been previously recorded in adults, was for the first time derived successfully in 27 of 31 children (87%). The values of the sinuatrial conduction time were then precisely measured directly according to the electrocardiogram from the sinus node. The sinuatrial conduction time measured directly was significantly longer in 6 children with sick sinus syndrome (138.3 +/- 10.3 msec, mean +/- standard deviation) than in 21 normal children (66.9 +/- 14.4 msec, mean +/- standard deviation). No overlap was found between them. Furthermore, comparison was made between the children and the adults (7 cases with sick sinus syndrome, 32 cases with normal sinus nodal function). The results suggested that the electrocardiogram recorded from the sinus node may be a valuable and promising technique for the evaluation of sinus nodal function and in the accurate diagnosis of the sick sinus syndrome in children.

Adolescent↗