Biomedical subjects

Y L Chen

Publications and source records attributed to Y L Chen.

At least 163 records · Page 9Linked to original sources

PubMed1994

Genotoxicity of 1,3-dithiane and 1,4-dithiane in the CHO/SCE assay and the Salmonella/microsomal test.

1,3-Dithiane and 1,4-dithiane are the sulfur-containing Maillard reaction products (MRPs) which have been found in boiled beef extracts. In this study the genotoxicity of these products was examined using the Salmonella/microsomal test and the CHO/SCE assay. 1,3-Dithiane showed a potent direct-acting mutagenicity toward S. typhimurium TA98 and TA100, but 1,4-dithiane had a lower mutagenicity toward both tester strains. Both compounds were shown to be non-mutagenic with hepatic metabolic activation with the exception of 1,3-dithiane toward strain TA100. To compare the mutagenic potential of 1,3-dithiane and 1,4-dithiane with other types of MRPs, 24 MRPs were examined for their mutagenicity to S. typhimurium TA98 and TA100 in the presence or absence of S9 mix. 2,6-Dimethylpyrazine, furan, 2-acetylpyrrole, and thiazole were shown to be mutagenic. However, these four MRPs exhibited a lower mutagenicity in TA98 than 1,3-dithiane and 1,4-dithiane. Furthermore, SCE frequencies in CHO cells were very significantly induced by 1,3-dithiane in the absence of S9 mix, but the SCE-inducing capability of 1,3-dithiane was reduced or even disappeared with metabolic activation. 1,4-Dithiane did not significantly induce SCE frequencies in the presence or absence of S9 mix. Thus, we concluded that 1,3-dithiane was a potent mutagenic MRP in the Salmonella/microsomal test, whereas it was a weak SCE inducer in the CHO/SCE assay.

Animals↗

PubMed1994

Cloning, overexpression and isolation of the type II FDP aldolase from E. coli for specificity study and synthetic application.

A stable overexpression E. coli strain containing the plasmid pKEN 2 for the production of the Zn(2+)-dependent FDP aldolase from E. coli has been developed. Approximately 14,000 U of the enzyme (specific activity = 23.3 U/mg) can be obtained from 4-L of growth medium. The enzyme was isolated, purified to homogeneity and used for the studies of stability, substrate specificity and metal ion replacement and dissociation. Crystals of the enzyme have been obtained for structural analysis. This E. coli strain was deposited with the American Type Culture Collection (ATCC #77472).

Base Sequence↗

PubMed1994

Acute-phase response, interleukin-6, and alteration of cyclosporine pharmacokinetics.

OBJECTIVE: Administration of interleukin-6 partially reproduces the inhibitory effects of the acute-phase response on cytochrome P450-dependent drug metabolism. The aim of the study was to determine whether endogenous cytokine has such an effect in patients treated by cyclosporine, which is metabolized by the cytochrome P4503A subfamily. METHODS: Blood cyclosporine and serum interleukin-6 levels were determined in six patients undergoing bone marrow transplantation, as long as they received cyclosporine by continuous infusion. Two serum acute-phase proteins, C-reactive protein and alpha 1-acid glycoprotein, and two cyclosporine metabolites, AM1 and AM9, were also determined. RESULTS: At the time of marrow infusion, levels of specific markers of inflammation were low. A peak in interleukin-6 level was then observed a mean of 10.8 days after transplantation, closely associated with variations in C-reactive protein levels. A parallel twofold increase in AM1 concentrations was observed, followed by a three-fold increase in cyclosporine levels, which peaked 4.8 days after interleukin-6. The times of peak cyclosporine and AM1 levels correlated with the time of peak interleukin-6 levels. AM9 was detectable in three patients but concentrations fell when interleukin 6 became detectable. CONCLUSIONS: An inflammatory reaction could be an important source of intraindividual variability in cyclosporine pharmacokinetics, possibly through an inhibition of cytochrome P4503A-dependent enzyme activities by endogenous interleukin-6. Blood AM1 accumulation might be explained by a secondary metabolic step that is highly sensitive to the inhibitory effect of interleukin-6.

Acute-Phase Reaction↗

PubMed1994

Craniofacial hyperhidrosis treated with video endoscopic sympathectomy.

Craniofacial hyperhidrosis as well as palmar hyperhidrosis is an abnormal state of local excessive sweating of unclear etiology. The hyperhidrosis may be isolated in the craniofacial region or associated with palmar hyperhidrosis. The patient's face is so wet with sweat that their daily activities are often seriously disturbed. To the best of our knowledge, there has been no satisfactory medical therapy, nor any effective surgical treatment reported in the literature. In 1991, we started to treat a patient with such distress using endoscopic ablation of the sympathetic T2 segment, because we mastered the technique after treating a large series of palmar hyperhidrosis patients. Furthermore, we were impressed by concomitant reduction of craniofacial sweating after T2-3 sympathectomy resulting from the relatively different domination of sympathetic supply between the eye and face. It appears possible to relieve excessive sweating of the head and face, without producing ptosis or miosis by ablation of the T2 segment. During the past 2 years, 7 patients with severe craniofacial hyperhidrosis have been successfully treated with the method and all obtained a satisfactory result. No complete Horner's syndrome has been produced except in one patient, who showed a mild and transient left eye ptosis, in whom coagulation of the sympathetic trunk higher than the T2 segment was performed. Intraoperative monitoring of forehead skin perfusion and observation of the change of pupillary size is emphasized during the lesion making. The longest postoperative follow-up was 2 years, with a mean follow-up of 12.4 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Morphological evidence for the antiatherogenic effect of scoparone in hyperlipidaemic diabetic rabbits.

OBJECTIVE: Scoparone (6,7-dimethoxycoumarin), a coumarin isolated from a hypolipidaemic Chinese herb Artemisia scoparia, has vasodilator and antiproliferative activities and possesses free radical scavenging properties in vitro. The aim of the study was to investigate the morphological effects of scoparone in the antiatherogenic process in vivo by using hyperlipidaemic diabetic rabbits as an animal model. METHODS: Male New Zealand White rabbits were divided into three groups: control (normal), hyperlipidaemic diabetic, and scoparone treated hyperlipidaemic diabetic. The plasma concentration of total cholesterol and triglycerides were determined. The thickness of the tunica intima was measured on paraffin sections of the aortas stained with Movat's pentachrome. The aortic samples were also processed for scanning and transmission electron microscopy. RESULTS: Neither the lipid profile in the plasma nor the structures of the aortic wall from the control group showed abnormalities. In contrast, the aortas from the hyperlipidaemic diabetic group showed prominent atherosclerotic plaques. Large numbers of monocytes were found adherent to the luminal surface and a markedly thickened intima filled with many lipid laden foam cells was clearly observed. By comparison, the scoparone treated group showed less advanced atherosclerosis with a lower plasma cholesterol. In the scoparone treated rabbits, the proportion of the aortic surface area covered with macroscopic plaques was 30%, and the thickness of the tunica intima 17%, of that of the non-scoparone treated hyperlipidaemic diabetic rabbits. CONCLUSIONS: Scoparone has an antiatherogenic action in hyperlipidaemic diabetic rabbits.

Animals↗

PubMed1994

AJ-FS1 monoclonal antibody detects a novel group of non-glycosylated antigens within the human sperm tail fibrous sheath.

AJ-FS1 is one of a new series of monoclonal antibodies (MoAbs) raised by immunizing mice with isolated human sperm tail fibrous sheath. Using indirect immunofluorescence (IIF), the AJ-FS1 MoAb did not react with the surface antigens of viable sperm, but did stain the flagellar principal piece of sperm dried onto slides or those demembranated with 1% Triton X-100. The specificity of the antibody for the fibrous sheath was confirmed by immunogold electron microscopy which showed the distribution of gold particles on the outer fibrous sheath surface, and its reaction with the Western blots of purified fibrous sheath preparations where multiple protein bands with mol. wt ranging between 97 and 28 kDa were identified. The same peptides were also detected in urea-dithiothreitol (DTT) fraction of sequentially extracted spermatozoa but not in Triton or Triton--DTT sperm lysates. The failure of sodium metaperiodate to abrogate the antibody reaction in both Western blotting and IIF indicated the non-glycosylated nature of the antigens. IIF screening of human testicular cryostat sections with AJ-FS1 MoAb showed its reactivity with the assembled fibrous sheath of maturing sperm tails only; thus indicating the late appearance of the antigens during spermatogenesis. The antibody did not react with skin, oesophagus, tongue, liver, kidney, placenta, uterus, cervix or their blood vessels. The significance of these results is discussed together with the importance of AJ-FS1 MoAb as a specific probe for the characterization of the fibrous sheath antigens in both normal and abnormal flagella.

Antibodies, Monoclonal↗

PubMed1994

Relationship of eye movement to computed tomographic findings in patients with Graves' ophthalmopathy.

To elucidate the relationship between eye movement and computed tomographic findings, 101 patients with Graves' ophthalmology were studied. Eye movements were scaled 0 to 3 according to movability. Extraocular muscle width and area were calculated from the largest portion of each muscle from the orbital coronal CT sections. Muscle widths were measured manually and muscle areas were calculated by a digitizer. The width and area of each rectus muscle were significantly correlated with limitation of eye movement. The muscle widths and areas were also significantly correlated to each other (r = 0.91 to 0.77, p < 0.001). Limitations of supraduction and abduction from enlargement of the inferior and medial rectus muscles were the most common clinical findings (46.5% and 39.6%, respectively). In conclusion, this study establishes a relationship between limitation of eye movement and extraocular muscle enlargement. Calculation of the width from the largest portion of the muscle manually from orbital coronal section is a simple method for clinical assessment of the severity of extraocular muscle involvement.

Adolescent↗

PubMed1994

Permeability of the pineal organ of the golden hamster (Mesocricetus auratus) to HRP with special reference to different types of blood capillaries.

The pineal organ of the golden hamster consists of deep and superficial portions which are connected to each other by a stalk. The permeability of capillaries for horseradish peroxidase (HRP) injected intravenously was examined in sections of entire portions of the gland that cut either along coronal or sagittal planes. Two distinct portions of the parenchyma, i.e., dorsal major and ventral minor ones, were found in the superficial gland. Most of the capillaries in the dorsal portion were of the continuous type of endothelium, whereas those in the ventral portion were fenestrated. In the dorsal portion, HRP readily crossed the endothelium, permeated the basal lamina, flowed into the perivascular connective tissue space and intruded into the intercellular clefts of the parenchyma. In contrast, HRP was not found to penetrate through the endothelium of the capillaries in the ventral portion to reach the perivascular area, thereby leaving the intercellular clefts of the parenchyma free of HRP. In the deep gland the capillaries were exclusively of the nonfenestrated type. Intravenously injected HRP was prevented from crossing the endothelium by the tight junction. In some areas, HRP penetrated through the capillaries in the pia mater, and crossed the outer limiting membrane to reach the intercellular clefts of the parenchyma and the basal lamina of the capillaries in the peripheral region of the deep pineal gland. The junctions between endothelial cells were not penetrated by HRP. The observations indicate that the type of capillary, absence of perivascular spaces, and permeability in the deep pineal are all similar to these factors in the general brain tissue; they differ from these in the superficial pineal gland, in which the dorsal portion shows characteristics found in other endocrine glands, but the ventral zone exhibits a unique situations: the presence of a blood-pineal barrier with a pericapillary connective tissue area.

Animals↗

PubMed1994

[Clinical analysis of 60 cases of nosocomal pneumonias].

This article gives a clinical analysis upon 60 cases of nosocomial acquired pneumonia. All the patients are > 18 years old and the onset time ranged from 3 to 180 days after they were hospitalized with an average of 38.77 days, mostly 30 days after admission (27 cases, 49%). Among the primary diseases, the hematologic disorder (18 cases, 30%) rank the first, followed by cerebrovascular disease (9 cases, 15%) and connective tissue disease (8 cases, 13.3%), The common inducing factors are the using of corticosteroids and chemotherapy (34 cases, 58%), tracheotomy and tracheal cannula (7 cases, 11.6%). Fever occurs in 96% of the patients and cough 63.3%. The positive rate of sputum bacterial culture is 95.46%. Pseudomonas aeruginosa isolated in 25 cases (56.8%). and Klebsiella pneumoniae 18 cases (40%). P. aeruginosa shows resistant to the third generation of cefalosporins more than before, and is sensitive to ciprofloxacin and polymyxin B, while K. pneumoniae is resistant to many kinds of antibiotics, especially ampicilline and carbenicilline. The death rate of infection of P. aeruginosa is 58.33% (14/25) and that of K. pneumoniae is 60% (12/18), that of mixed infection is 66.67% (16/23).

Adult↗

PubMed1994

[A transposition of iliopsoas in replacement of pelvic floor for incontinence of urination and/or defecation in children].

Fourteen patients, the age ranged from 2 to 12 years, with fecal and/or urinary incontinence were treated between 1991 and 1993 using a transposition of iliopsoas in replacement or strengthening of pelvic floor. The results were encouraging. The evaluation of the function of pelvic floor was described. Levator plays an important role in normal mechanism of defecation as well as urination. Several types of incontinence develop while the disfunction of pelvic floor occur and some function of continence could be restored by an operation of transposition of iliopsoas.

Child↗

PubMed1994

[Methicillin-resistant Staphylococcus aureus infection and its treatment in burned patients].

Burn wound and systemic infections caused by methicillin-resistant Staphylococcus aureus (MRSA) were analysed in 95 patients. Results showed that both 95 (92.2%) out of 103 strains of Staphylococcus aureus isolated from burn wound and all 17 strains from blood were MRSA. Wound MRSA infection could be found in patients with variety of severity and in any kind of wound, while systemic MRSA infection was often occurred in extensive burn patients. The isolated MRSA were most resistant to cephalosporins and sensitive to vancomycin. In order to control wound MRSA infection, Lysostaphin which is active against these organisms could be used as a topical antimicrobial.

Administration, Cutaneous↗

PubMed1994

Ultrasonography and needle aspiration cytology in the diagnosis and management of parathyroid lesions.

To elucidate the diagnostic value of fine needle aspiration (FNA) cytology of ultrasonically suspected parathyroid lesions, we reviewed a series of 17 cases seen over the past two years. Patients with biochemically proven primary or secondary hyperparathyroidism were examined by ultrasonography using a 7.5-MHz linear transducer. Ultrasound-guided FNA cytologic examinations with Riu's stain were performed on 13 patients who had questionable ultrasonographic patterns. The aspirates were considered adequate in nine out of 13 cases (69%). The cytologic patterns, characterized by tight cohesion of naked nuclei with indistinct cell border showing hypermonomorphism and overlapping of nuclei, were noted in adenomatous and hyperplastic lesions. There were several different findings noted in the case of parathyroid carcinoma, including loose cohesion of nuclei, larger nuclear size, and prominent anisokaryosis. One patient with secondary hyperparathyroidism who previously had a neck exploration, received an ultrasonically-guided percutaneous alcohol injection to the parathyroid lesion after cytologic verification. The result was remarkable both in volume reduction and in clinical improvement. The results suggest that ultrasound-guided FNA cytologic examination with Riu's stain is safe, simple and helpful in the localization of parathyroid lesions prior to surgery or percutaneous alcohol ablation therapy.

Adenoma↗

PubMed1994

Influence of smoking on Graves' disease with or without ophthalmopathy and nontoxic nodular goiter in Taiwan.

The effect of smoking habits on Graves' disease with or without ophthalmopathy and nontoxic nodular goiter has been discussed for more than 10 years in Western countries, but there are no published reports from Oriental countries, where the prevalence of cigarette smoking among women is lower than in Western women. The purpose of this study was to determine the relationship between smoking and Graves' ophthalmopathy, Graves' disease without ophthalmopathy, and nontoxic nodular goiter in Taiwan. The study included 349 patients with thyroid disease from endocrinologic clinics, including 116 patients with Graves' ophthalmopathy (92 women, 24 men), 108 patients with Graves' disease but without ophthalmopathy (96 women, 12 men), and 125 patients with nontoxic nodular goiter (114 women, 11 men). Information on smoking habits at the time of onset of the disease was obtained by a self-administered structured questionnaire. Since women generally smoke less than men, female and male smoking habits were compared separately with those of controls matched with patients on the basis of age. There was a significantly higher prevalence of cigarette smoking in women with Graves' ophthalmopathy and nontoxic nodular goiter than for healthy female controls, showing an odds ratio of 8.15 and 6.48, respectively, despite a lower prevalence of cigarette smoking in Taiwan (7.6% in women with Graves' ophthalmopathy, 6.1% in women with nontoxic nodular goiter) than in the West (64.2% in women with Graves' ophthalmopathy, 30% in women with nontoxic nodular goiter). Men in these three disease groups and women with Graves' disease without ophthalmopathy showed no significant association with cigarette smoking.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

[Topical fibronectin for enhancement of burn healing].

The effects of fibronectin (Fn) on burn healing were observed in mice. A split thickness burn covered 7% approximately 8% TBSA was created on the back of mouse. Experimentally 0.05ml of Fn (0.5mg/ml) was topically applied daily. Wound healing time and healing rate were determined. On 5 and 10 postburn days, biopsy sample of wound tissue was obtained. Total protein, DNA, and hydroxyproline contents were measured according to Bradford method, Hoechest 33258 dye fluorometry, and routine measure respectively. The mean wound healing time in mice treated with Fn was 18.67 +/- 4.50 days compared to 22.89 +/- 2.85 days in the controls. The wound healing rate was significantly higher in the Fn-treated mice. The contents of wound tissue DNA and hydroxyproline in Fn group were significantly increased on day 5, and total protein was significantly increased on day 10. This study indicated that topical application of Fn is beneficial to wound healing.

Administration, Cutaneous↗

PubMed1994

Direct visualization of cavitation and damage in ultrathin liquid films.

The Surface Forces Apparatus technique was used to observe, at the nanoscopic level, the rapid growth and disappearance of vapor cavities between two moving solid surfaces while simultaneously monitoring their effects on the deformations and damage produced on the surfaces. Both approach-separation and shear motions were studied. In both geometries, as the relative velocity between the two surfaces increases, they deform 'elastohydrodynamically'; in some regions the surfaces become flattened (corresponding to the build up of positive or compressive pressure in the adjacent liquid) while in other regions the surfaces become pointed (corresponding to negative or tensile pressure). Vapor cavities nucleate at these pointed regions once the relative velocity of the two surfaces exceeds a certain critical value. The sudden nucleation and growth of a cavity in a thin liquid film is seen to be a much more violent event than its subsequent collapse, and surface damage due to cavitation occurs during the inception rather than during the much smoother collapse of cavities. These studies are the first to directly visualize cavity formation and associated damage in ultrathin lubricating films, and provide a fairly detailed picture of both of these mechanisms and the relationship between them. The picture that emerges in complex and different from the currently accepted model, in which damage is caused during the collapse of cavities rather than their growth. The results should have a bearing on all phenomena where cavitation and cavitation damage occur in thin lubricating films.

Aluminum Silicates↗

PubMed1993

The effect of copper ion on arachidonic acid metabolism in the porcine corneal epithelium.

The effect of copper ion on arachidonic acid metabolism in the corneal epithelium was studied. Our results showed that when 3H-arachidonic acid (1 microCi/microgram) was incubated with homogenate of corneal epithelium at 37 degrees C for 45 min., three metabolites were formed. Metabolite A, the major metabolite, was identified as 12-HETE by HPLC and GC. An analysis with chiral phase HPLC revealed that metabolite A was a (R)-enantiomer. The production of 12(R)-HETE was stimulated by low concentrations of CuCl2 (< 0.1 mM) and inhibited by higher concentrations of CuCl2. Study on the biological activity of 12(R)-HETE showed that it could stimulate migration of endothelial cells in a concentration as low as 10 ng/ml. These results suggest that one of the effects of copper ion on the corneal neovascularization may be to regulate the level of 12(R)-HETE.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1993

Inhibition of human monocyte TNF production by adenosine receptor agonists.

Adenosine receptor agonists and agents enhancing pericellular concentrations of adenosine possess antiinflammatory properties. In the present study, we found that R-phenylisopropyladenosine (R-PIA), 5'-N-ethylcarboxamido adenosine (NECA), other agonists of adenosine receptors and dipyridamole, an adenosine uptake inhibitor, inhibited tumor necrosis factor (TNF) production by endotoxin-stimulated human monocytes in a concentration-dependent manner with no inhibition of interleukin-6. The rank order of agonist potency is characteristic of neither A1 nor A2 receptors and suggests the involvement of another receptor subtype. The effect of R-PIA on TNF was in part abolished by the antagonist 8-sulfophenyltheophylline. In endotoxin-treated rats, R-PIA pretreatment (2.5 mg/kg) reduced serum TNF levels by 98%, with no modification of serum IL6 levels. TNF inhibition could be an important mechanism by which adenosine analogs exert their antiinflammatory action.

Adenosine↗

PubMed1993

Protection by scoparone against the alterations of plasma lipoproteins, vascular morphology and vascular reactivity in hyperlipidaemic diabetic rabbit.

1. The in vivo pharmacological effects of scoparone (6,7-dimethoxycoumarin) in a hyperlipidaemic diabetic rabbit model were investigated. 2. Three groups of rabbits were studied: (1) normal, (2) hyperlipidaemic and diabetic-untreated and (3) hyperlipidaemic and diabetic-scoparone treated. The hyperlipidaemic diabetic rabbits were fed with 1% cholesterol and treated with alloxan, a diabetogenic agent. The plasma levels of total cholesterol, total triglyceride, very low-density lipoprotein (VLDL) cholesterol, low density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol were markedly increased as soon as the rabbit became diabetic at the second week. Scoparone-treatment (5 mg kg-1 day-1, s.c.) significantly reduced the plasma lipid and lipoprotein cholesterol levels of the hyperlipidaemic diabetic rabbit to 73.3% of total cholesterol, 48.3% of total triglyceride, 66.0% of VLDL cholesterol, 55.7% of LDL cholesterol and 79.5% of HDL cholesterol. 3. Six weeks after cholesterol-feeding, the aortic arch and thoracic aorta were dissected for morphological and functional studies. In vascular rings from the untreated hyperlipidaemic diabetic rabbit, there was intimal thickening with accumulation of fatty streaks, foam cells and migration of smooth muscle cells to the intima. In the rabbits treated with scoparone, there were fewer pathological morphology changes found in vascular segments than in the untreated hyperlipidaemic diabetic rabbits. 4. In the vascular reactivity experiments, the phenylephrine-induced contraction and nitroprusside induced dilatation did not differ significantly among the three rabbit groups, except that the contraction was enhanced in the thoracic aorta of hyperlipidaemic diabetic rabbits either untreated or treated withscoparone, as compared to the normal group, and the sensitivity to nitroprusside was increased in the thoracic aorta of the scoparone-treated group as compared to the untreated group.5. The endothelium-dependent dilatation induced by acetylcholine was significantly attenuated in both the aortic arch and thoracic aorta from the hyperlipidaemic diabetic rabbits as compared to the normal rabbits. This attenuation was partially prevented, when scoparone (5 mg kg-1) was administered daily.6. These results suggest that scoparone protects against some alterations of plasma lipoproteins,vascular morphology and vascular reactivity in the hyperlipidaemic diabetic rabbit. These protective effects of scoparone may be partly related to its free radical scavenging property.

Animals↗