Biomedical subjects

C H Lin

Publications and source records attributed to C H Lin.

At least 325 records · Page 18Linked to original sources

PubMed1993

Effects of monoamine precursors on food intake in male rats.

Effects of monoamine precursors on food intake in male rats were studied. Rats were subjected to an artificial circadian pattern of eating, i.e., a five-hour feeding program during daytime and food deprived during the rest of day. Feeding responses after treatment of drugs were examined. Intraperitoneal injection of L-beta-3, 4-dihydroxyphenylalanine (L-DOPA), DL-threo-dihydroxyphenylserine (DOPS), or 5-hydroxy-L-tryptophan (5-HTP) suppressed food intake. The suppression occurred within the first thirty minutes of the test period and their order of potency came out 5-HTP > L-DOPA = DOPS. The suppressive action of 5-HTP was very strong and lasted at least 3 days. The mechanism of this feeding suppressed action by either the central satiety center or the peripheral inhibiting system was discussed in this context.

5-Hydroxytryptophan↗

PubMed1992

Triflavin, an Arg-Gly-Asp containing snake venom peptide, inhibits aggregation of human platelets induced by human hepatoma cell line.

Triflavin, an Arg-Gly-Asp (RGD)-containing peptide, purified from snake venom of Trimeresurus flavoviridis, inhibits human platelet aggregation through the blockade of fibrinogen binding to fibrinogen receptors associated with glycoprotein IIb/IIIa complex. In this report, we examined the effect of triflavin on tumor cells (human hepatoma J-5)-induced platelet aggregation (TCIPA) of heparinized platelet-rich plasma (PRP). ADP-scavenger agents, apyrase (10 U/ml) and creatine phosphate (5 mM)/creatine phosphokinase (5 U/ml) did not inhibit TCIPA while hirudin (5 U/ml) completely inhibited it. J-5 cells initially induced platelet aggregation, then blood coagulation occurred. J-5 cells concentration-dependently shortened the recalcification time of normal as well as Factor VIII, IX-deficient human plasmas, while it was inactive at shortening the recalcification time of Factor VII-deficient plasma, suggesting J-5 cells induced platelet aggregation through activation of extrinsic pathway, leading to thrombin formation as evidenced by the amidolytic activity on s-2238 by expressing tissue factor-like activity. Triflavin inhibited TCIPA in a dose-dependent manner (IC50, 0.02 microM). When compared on molar ratio, triflavin was approximately 30,000 times more potent than GRGDS (IC50, 0.58 mM). On the other hand, GRGES showed no significant effect on TCIPA, even its concentration was raised to 4 mM. Additionally, the monoclonal antibodies, raised against glycoprotein IIb/IIIa complex (i.e., 7E3 and 10 E5) inhibited J-5 TCIPA. In conclusion, we suggest the inhibitory effect of triflavin on J-5 TCIPA may be chiefly mediated by the binding of triflavin to the fibrinogen receptor associated with glycoprotein IIb/IIIa complex on platelet surface membrane.

Amino Acid Sequence↗

PubMed1992

Novel form of growth cone motility involving site-directed actin filament assembly.

Regulation of cytoskeletal structure and motility by extracellular signals is essential for all directed forms of cell movement and underlies the developmental process of axonal guidance in neuronal growth cones. Interaction with polycationic microbeads can trigger morphogenic changes in neurons and muscle cells normally associated with formation of pre- and postsynaptic specializations. Furthermore, when various types of microscopic particles are applied to the lamellar surface of a neuronal growth cone or motile cell they often exhibit retrograde movement at rates of 1-6 microns min-1 (refs 3-6). There is strong evidence that this form of particle movement results from translocation of membrane proteins associated with cortical F-actin networks, not from bulk retrograde lipid flow and may be a mechanism behind processes such as cell locomotion, growth cone migration and capping of cell-surface antigens. Here we report a new form of motility stimulated by polycationic bead interactions with the growth-cone membrane surface. Bead binding rapidly induces intracellular actin filament assembly, coincident with a production of force sufficient to drive bead movements. These extracellular bead movements resemble intracellular movements of bacterial parasites known to redirect host cell F-actin assembly for propulsion. Our results suggest that site-directed actin filament assembly may be a widespread cellular mechanism for generating force at membrane-cytoskeletal interfaces.

Actins↗

PubMed1992

HA-29: an inhibitor of thromboxane A2 formation with antagonism of thromboxane A2/prostaglandin endoperoxide receptor in rabbit platelets.

HA-29, 2-[(3-methoxyphenyl)methyl]-pyrano[2,3-c]pyrazol-6(1H)-one, was investigated for its inhibitory mechanism of action in washed rabbit platelets. This compound inhibited the aggregation and ATP release of rabbit platelets induced by arachidonic acid and collagen in a concentration-dependent manner, without affecting those induced by ADP, PAF and thrombin. Prolongation of the incubation time of HA-29 with platelets did not cause further inhibition and the aggregability of the agent-treated platelets could be restored after washing of platelets. The concentration-response curve of U-46619-induced platelet aggregation was shifted to the right by HA-29 in a concentration-dependent manner, but the maximal aggregation was suppressed by HA-29. The pA2 and pA10 values of HA-29 on U-46619-induced platelet aggregation were 4.26 and 3.58, respectively, with a slope value of -1.4. The U-46619-induced aggregation was markedly disaggregated by HA-29 even it was added 5 min after U-46619. HA-29 inhibited the secondary aggregation and ATP release, but not the primary aggregation of human platelet-rich plasma induced by ADP and epinephrine. Thromboxane B2 formation caused by arachidonic acid, collagen and thrombin was markedly suppressed by HA-29. HA-29 also inhibited the formation of prostaglandin D2 caused by arachidonic acid. HA-29 inhibited almost completely the formation of inositol monophosphate caused by U-46619, but not that by collagen or thrombin. HA-29 did not affect U-46619-induced contraction of rat aorta. It is concluded that the antiplatelet effect of HA-29 is due to the inhibition of thromboxane A2 formation and blockade of thromboxane A2/prostaglandin endoperoxide receptor.

Adenosine Triphosphate↗

PubMed1992

Identification of a missense phenylketonuria mutation at codon 408 in Chinese.

A single base transition of G to A at codon 408 of the phenylalanine hydroxylase gene is identified. This missense mutation results in the substitution of Arg408 for Gln408 (R408Q) and accounts for about 5% of phenylketonuria (PKU) chromosomes among Chinese. This mutation is in linkage disequilibrium with restriction fragment length polymorphism haplotype 4. In addition, another mutation (R408W), at the same codon and prevalent on haplotype 2 PKU chromosomes in Caucasians, is identified in a PKU allele of haplotype 41. Previously, this mutation has been observed on a haplotype 44 background in Chinese PKU patients.

Alleles↗

PubMed1992

Chemical burn with cresol intoxication and multiple organ failure.

In general, immediate water irrigation is recommended for all chemical burns. Very few chemicals cannot be safely washed off the skin with water, however cresol is one of the exceptions. A 40 per cent TBSA cresol chemical burn that subsequently developed systemic intoxication and multiple organ failure is reported. The patient survived after intensive general supportive treatment, repeated haemodialysis and wound care.

Burns, Chemical↗

PubMed1992

Gastric emptying using three different formulas in infants with gastroesophageal reflux.

The role of delayed gastric emptying (GE) in the pathogenesis of gastroesophageal reflux (GER) in infants is controversial at present. GE has been shown to be altered by the composition and osmolality of the feedings. This prospective study was undertaken to assess the changes in the GE and the percentage of time GER was detected by scintigraphy using three different formulas on consecutive days in infants with GER. Twenty-eight infants under 1 year of age diagnosed to have GER by extended intraesophageal pH monitoring (pH being less than 4.0 for greater than 5% of the duration of the test), underwent scintigraphy on three consecutive days using the same volume per single feeding of a casein-predominant, soy, or a whey-hydrolysate formula in a randomized order. The formulas were isocaloric. Gastric emptying and percentage of GER into the esophagus were estimated for 60 min following these feedings. Mean GER percent during the study was 20.39, 17.68, and 16.34 on casein-predominant, soy, and whey-hydrolysate formulas, respectively, and was not significantly different. Mean values of GE were 39.7%, 44.6%, and 48.5% on casein, soy, and whey formula, respectively. No significant difference in GE was also observed between casein-predominant and soy formula. However, a significant difference was observed (p less than 0.05) on GE between casein-predominant and whey-hydrolysate feedings. Our data suggest that formula selection may be important in the treatment of conditions associated with delayed gastric emptying.

Gastric Emptying↗

PubMed1992

Triflavin, an Arg-Gly-Asp-containing antiplatelet peptide inhibits cell-substratum adhesion and melanoma cell-induced lung colonization.

Triflavin, an Arg-Gly-Asp (RGD) containing peptide purified from Trimeresurus flavoviridis snake venom, inhibits human platelet aggregation by blocking fibrinogen binding to fibrinogen receptors associated with glycoprotein IIb/IIIa complex. In this study, we show that triflavin (1-30 micrograms/mouse) inhibits B16-F10 melanoma cell-induced lung colonization in C57BL/6 mice in a dose-dependent manner. In vitro, triflavin dose-dependently inhibits adhesion of B16-F10 melanoma cells to extracellular matrices (ECMs; i.e., fibronectin, fibrinogen, vitronectin, and collagen type I). Triflavin is approximately 600-800 times more potent than GRGDS at inhibiting cell adhesion. In addition, triflavin dose-dependently inhibits B16-F10 cell-induced platelet aggregation. These results imply that the inhibitory effect of triflavin on the adhesion of tumor cells to ECMs (e.g., fibronectin, vitronectin and collagen type I) and/or tumor cell-induced platelet aggregation may be partially responsible for its antimetastatic activity in C57BL/6 mice.

Animals↗

PubMed1992

The pharmacological and pathological studies on Taiwan folk medicine (VII): The anti-inflammatory effect of Echinops grjiisii.

The hepatotoxic-protective effects of "San-fang-feng" (the root of E. grijisii) and "Lou-lu" (the root of E. latifolius) on CCl4 induced hepatotoxicity have been proposed in our previous paper (Lin et al, 1990). The anti-inflammatory effects of these two crude drugs were investigated in this experiment. The results indicated that both of them displayed pronounced anti-inflammatory activities against carrageenan-induced edema. Furthermore, in order to isolated the main active components of E. grijisii, fractions obtained from the methanolic extract of E. grijisii were investigated in mice for their 24-h LD50 and 95% confidence limits, which could be used as a guiding for further animal experiments. Our findings demonstrated that n-hexane (100,300 mg/kg), chloroform (30,100, 300 mg/kg) and ethyl acetate (30,100, 300 mg/kg) fractions could markedly inhibit the carrageenan-induced inflammation, and the main active principle was found to be concentrated in the chloroform fraction, which possessed significant inhibitory activities even more than does indomethacin.

Animals↗

PubMed1992

Pure rhabdomyosarcoma of the corpus uteri in a postpartum patient: report of a case and review of the literature.

Pure rhabdomyosarcomas originate in the female genital tract. They are uncommon and most often occur in infancy or childhood as sarcoma botryoides (embryonal rhabdomyosarcoma) which involve the vagina and cervix. Such tumors rarely occur in adults. A pure rhabdomyosarcoma of the uterus that arose in a postpartum patient is described. The pertinent literature is discussed.

Adult↗

PubMed1991

Essential role for polyamine biosynthesis in thyroxine stimulated pancreatic development in neonatal rats.

Administration of thyroxine to rat pups leads to precocious development of the pancreas. The role of ornithine decarboxylase (ODC) and polyamines in thyroxine-induced pancreatic maturation was examined. Rat pups (aged 5 days) were given daily subcutaneous injection of thyroxine (0.1 micrograms/g body wt.) until the day before death. Serial ODC activities were measured in pancreatic homogenates after 1, 2, 3, 4, 5, 6, 7 and 10 days of thyroxine treatment. There was a biphasic induction of ODC activities by thyroxine: an early peak appeared on day 2 of treatment followed by a decrease on day 4; a second peak was evident on day 5 and then a decrease to control values by day 7. Significant increases in tissue concentrations of putrescine and spermidine were observed concomitant with two peaks of ODC activity. Pancreatic amylase concentration, DNA and protein also showed a significant increase after thyroxine treatment. Difluoromethyl ornithine (DFMO), a specific ODC inhibitor, given orally (8% in drinking water) to nursing dams at postnatal day 5 for 5 days caused an 83% inhibition of pancreatic ODC activity in thyroxine-treated pups when compared to thyroxine-treated pups not exposed to DFMO. Concomitantly, the thyroxine-induced increases in pancreatic weight, protein and amylase activity were suppressed. Our results suggest that increases in ODC activities and polyamine levels are critical intermediary steps in the precocious induction of pancreatic development by thyroxine.

Amylases↗

PubMed1991

Structure of the (+)-CC-1065-DNA adduct: critical role of ordered water molecules and implications for involvement of phosphate catalysis in the covalent reaction.

(+)-CC-1065 is an extremely potent antitumor agent produced by Streptomyces zelensis. The potent effects of (+)-CC-1065 and its alkylating analogues are thought to be due to the formation of a covalent adduct through N3 of adenine in DNA. It has been previously postulated, on the basis of modeling studies, that a phosphate may be involved in stabilization of the adduct and in acid catalysis of this reaction. In this study, using 1H NMR in combination with 17O-labeled water and phosphate, we demonstrate the involvement of a bridging water molecule between a phenolic proton on the alkylating subunit of (+)-CC-1065 and an anionic oxygen in the phosphate on the noncovalently modified strand of DNA. In addition, a second ordered water molecule associated with one of the protons on N6 of the covalently modified adenine is also identified. This structure has important implications for catalytic activation of the covalent reaction between (+)-CC-1065 and DNA and, consequently, the molecular basis for sequence-selective recognition of DNA by the alkylating subunit of (+)-CC-1065. On the basis of the example described here, the use of 1H NMR in 17O-labeled water may be a powerful probe to examine other structures and catalytic processes for water-mediated hydrogen-bonded bridges that occur between small molecules and DNA or enzymes.

Adenine↗

PubMed1991

Acute effects of oral pyridostigmine bromide on conditioned operant performance in rats.

Pyridostigmine bromide (Pyr), the current drug of choice in the management of myasthenia gravis, has been suggested for use in Alzheimer's dementia, and as a prophylactic treatment for intoxication with organophosphate cholinesterase inhibitors. The present study was undertaken to evaluate the dose-response and time-course effects of acute oral administration of Pyr over a broad dose range (3-40 mg/kg) on the lever pressing of rats maintained under a multiple fixed-ratio (FR-20) time-out schedule of reinforcement for water reward. The drug produced a dose-dependent biphasic response depression in the overall rate of FR responding. Low doses of Pyr (less than or equal to 12 mg/kg) that caused no gross signs of toxicity only moderately decreased rates of responding, primarily due to a decrease in response rates. Whereas high doses of Pyr (greater than 24 mg/kg) which produced overt signs of peripheral cholinergic intoxication markedly suppressed overall responding, primarily due to cessation of responding. The lowest effective dose of performance disruption was 6 mg/kg, and the ED50 was calculated as 23.3 (17.9-28.7) mg/kg. The time-course data of performance disruption showed that low doses of Pyr (less than or equal to 12 mg/kg) had an onset latency within 40-80 min and a duration of 20-80 min, whereas high doses (greater than or equal to 24 mg/kg) had an onset latency of 20-40 min and a duration greater than 80 min. These results suggest the recommended human therapeutic or prophylactic regimen of 30-120.mg Pyr, orally taken each 8 hours, might adversely affect behavioral performance.

Administration, Oral↗

PubMed1991

Electron microscopic studies of the endoplasmic reticulum in whole-mount cultured cells fixed with potassium permanganate.

A method for visualizing the endoplasmic reticulum and other membrane organelles in whole-mount cells with a standard, 60-kV transmission electron microscope has been developed. By use of a new formulation of potassium permanganate as a fixative, intracellular membranes were preserved and stained, while cytosolic proteins were digested, giving a pattern of membranous organelles against a clear background, suitable for transmission EM of whole-mount cells at 60 kV. Mitochondria, lysosomes, and ER were clearly visible in whole-mount cells fixed by this method. We have employed this technique to examine the organization of the ER in a variety of different cell lines. This method also allowed visualization of the three-dimensional organization, relationships, and fine structure of mitochondria. With prolonged permanganate fixation, mitochondrial cristae were clearly visible in whole-mount cells. This method was also useful for fixation and staining of thin sections, and allowed examination of thicker sections than previously possible, thus giving improved imaging of organelle relationships and fine structure. Using this method, we have examined the ER, mitochondria, and Golgi in thin section.

3T3 Cells↗

PubMed1991

Bovine brain microsomal CDP-diacylglycerol synthetase: solubilization and properties.

CDP-diacylglycerol(DAG) synthetase (EC 2.7.7.41) has been solubilized from bovine brain microsomes by the detergent CHAPS (3-[(3-cholamidopropyl) dimethylammonio] -1-propanesulfonate). Optimal solubilization with 1.5% CHAPS yielded 55-60% of the synthetase activity. The effect of CHAPS on the enzyme was biphasic inhibiting at 0.3% and giving maximal activity at 0.5% (the concentration used for all assays). The solubilized, but not the microsomal enzyme is activated by phosphatidylcholine (PC) and strongly inhibited by cardiolipin and lysoPC. Strong inhibition by N-ethylmaleimide, 5,5'-dithio-bis (2-nitrobenzoic acid) and p-chloromercuribenzoate supported a sulfhydryl requirement for the enzyme. Phosphatidic acid (PA) from egg lecithin and 1-stearoyl,2-arachidonoyl PA were preferred substrates for the microsomal synthetase. Solubilized synthetase showed selectivity for the latter PA which is consistent with this enzyme functioning to help form the preponderant 1-stearoyl,2-arachidonoyl species of phosphatidylinositol. Further attempts to purify the synthetase were unsuccessful. All findings suggested the enzyme exists as an unstable complex.

Animals↗

PubMed1991

Evaluation of the role of noradrenaline precursor on LH release induced by ovarian steroids.

The role of noradrenaline precursor on the release of luteinizing hormone-releasing hormone based on the plasma concentration of luteinizing hormone (LH) was studied in rats. Rats were ovariectomized at 1000h on diestrus day 1(D1) and primed with estradiol immediately after the operation. They received progesterone at 0930h in the next morning (the expected diestrus day 2, D2). Dynamic changes of plasma LH levels were examined in the afternoon of D2. Treatments and results are as follows: 1) Administration of DL-threo-dihydroxyphenylserine (DOPS, 200mg/kg BW, ip) at 0900h on D2, 30 min prior to progesterone treatment, results in 87.5% of rats showing LH surges. 2) Administration of 5-hydroxytryptophan (5-HTP, 100mg/kg BW, ip) 30 min before DOPS completely inhibits the action of DOPS on LH release induced by ovarian steroids. 3) Making a change of the whole working schedule of operation, estrogen was given 5 hours earlier on D1. DOPS and progesterone were given at 0500 hand 0530 h on D2, respectively. It does not induce the LH surge during the whole morning of D2. These results demonstrate that DOPS might just reduce the threshold of the central neurons governing LH release. The time in a fixed lighting schedule was important in determining the LH release induced by ovarian steroids.

5-Hydroxytryptophan↗

PubMed1991

Capability of ovarian steroids in inducing LH surges in acutely ovariectomized rats.

The capability of estradiol (E2) or E2 and progesterone (P4) in inducing luteinizing hormone (LH) surge in acutely ovariectomized (Ovx) rats was studied. In group I, rats were Ovx on estrus and were implanted with E2 capsules and atrial cannulae immediately after operation for blood samplings. In group II, rats were also Ovx on estrus but were implanted with E2 capsules and sampling cannulae the next day (the expected diestrus day 1, D1). In group III, rats were Ovx on D1, and were implanted E2 with capsules and atrial cannulae immediately after operation. All surgical operations were done around 1000h in the morning. On the expected diestrus day 2(D2) at 0930h, one half of the rats in each group received an oil vehicle or 2mg of P4 subcutaneously. Blood samples were taken from the indwelled cannulae at 1300, 1500, and 1700hrs in the afternoon. Results showed that P4 treatment amplified LH release in all three groups of rats primed with E2, and that the oil vehicle did not assist in LH release in E2 primed rats of group I and group II, but it did in 8 out of 10 rats in group III in the late afternoon of D2. Results suggested that the estradiol alone was capable in inducing LH surge on the expected D2 afternoon, and that under estradiol-primed conditions, P4 can trigger neural initiators to advance LH surge, but that the internal hormonal milieu at the time of ovariectomy may affect the influence of ovarian steroids in inducing LH release.

Animals↗

PubMed1991

The epidemiology of diarrhoeal diseases in southeastern China.

In a community survey of 19,410 people for 12 months in southeastern China (Fujian Province), the overall annual incidence rate of diarrhoea was 729.9 episodes/1,000 population. The incidence varied with different age groups; children aged under five years had the highest rate, 2.25 episodes per child per year. A bacterial pathogen was isolated from 883 cases (44.03%), and 147 (14.76%) strains from 996 healthy controls. Enterotoxigenic Escherichia coli, enteropathogenic E. coli, and Shigella species were the most frequently isolated bacterial pathogens. Isolation was highest during the hot summer months. The investigation showed that the diarrhoea incidence was related to the status of economy, education, healthy, hygiene, food, and water.

Adolescent↗