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Biomedical subjects

L Yang

Publications and source records attributed to L Yang.

At least 775 records · Page 43Linked to original sources
PubMed1991

[Clinical study of superoxide dismutase in recurrent aphthous ulceration].

Activity of superoxide dismutase (SOD) was determined in erythrocytes obtained from 74 patients with recurrent aphthous ulcerations (RAU) and 100 healthy individuals. The results showed that activity level of SOD in RAU was significantly lower as compared with that in the controls (P less than 0.01). The activity of SOD in 30 cases of RAU at interval period was elevated on reexamination, but it was still lower than that in the controls (P less than 0.01). There is evidence that damage of superoxide radicals (O.2) and decrease of activity of SOD may play important roles in the pathogenesis of RAU. A random double-blind, placebo-controlled, cross-over trial on membrane SOD was carried out in 40 patients with RAU. The results demonstrated that the effective rate of SOD was 90%, being markedly higher than that of placebo. It is suggested that membrane SOD, as a topical medicine, could increase the concentration of SOD on the ulcerous surfaces, prevent O.2-induced injury, decrease capillary permeability, relieve inflammation and improve cure of ulcer.

Administration, Topical↗
PubMed1991

Amino acid sequence of the 8-kDa protein in photosystem I reaction center complex from a thermophilic cyanobacterium, Synechococcus elongatus.

The 8-kDa protein in Photosystem I (PS I) reaction center complex was isolated from a thermophilic cyanobacterium, Synechococcus elongatus, by SDS-polyacrylamide gel electrophoresis using TRIS-Tricine buffer system. The complete amino acid sequence of the protein was determined. The 8-kDa protein consisted of 73 amino acid residues giving a calculated molecular weight of 7,472. No significant sequence homology were observed with the known other small subunits in PS I reaction center complex, except for the 6.5-kDa protein in PS I from another thermophilic cyanobacterium, S. vulcanus. The 8-kDa protein was characteristically rich in hydrophobic amino acid residues, especially the content of leucine. These suggest that the 8-kDa subunit is an intrinsic structure component in PS I core complex for stabilization of the reaction center.

Amino Acid Sequence↗
PubMed1991

[Galactosyl neoglycoalbumin:preparation and studies of its binding with hepatic special receptor].

Galactosyl-neoglycoalbumin (NGA) can bind with the asialoglycoproteins receptor specifically on the surface of mammal's liver. We prepared NGA in different carbohydrate density and made some animal and clinical tests with technetium-99m labeled NGA. The maximum absorption of 99mTc-NGA-21 was 82.6% in liver. We also got the satisfactory radiographs of liver. NGA was synthesized by the covalent coupling of a carbohydrate bifunctional reagent, 2-imino-2-methoxyethyl-1-thio-galactose (4), to human serum albumin. The cyanomethyl-1-thio-glycoside of beta-D-galactose (3) was prepared from the pseudothiourea derivative (2) which was synthesized by acetylation, bromination and substitution of galactose (3) could be converted to (4) by treatment with sodium methoxide.

Albumins↗
PubMed1991

Modulation of extracellular matrix gene expression by heparin and endothelial cell growth factor in human smooth muscle cells.

We have previously shown that human vascular smooth muscle cells grown for several passages in the presence of heparin and endothelial cell growth factor (ECGF) exhibit profound alterations in the synthesis of extracellular matrix proteins. In the present study, we demonstrate that the mRNA steady-state levels for various matrix macromolecules were altered in the presence of heparin and ECGF, but not ECGF alone. Specifically, the expression of types I and IV collagens, fibronectin, and decorin proteoglycan genes were markedly inhibited, whereas that of versican proteoglycan and beta-actin genes were unaffected. The effects were fully reversible. The suppression of the collagen gene expression was related to decreased collagen production by cells incubated with heparin and ECGF. Thus, heparin and ECGF synergistically elicit a coordinate and selective inhibition of matrix gene expression in human smooth muscle cells.

Actins↗
PubMed1990

Prebiotic synthesis of histidine.

The prebiotic formation of histidine (His) has been accomplished experimentally by the reaction of erythrose with formamidine followed by a Strecker synthesis. In the first step of this reaction sequence, the formation of imidazole-4-acetaldehyde took place by the condensation of erythrose and formamidine, two compounds that are known to be formed under prebiotic conditions. In a second step, the imidazole-4-acetaldehyde was converted to His, without isolation of the reaction products by adding HCN and ammonia to the reaction mixture. LC, HPLC, thermospray liquid chromatography-mass spectrometry, and tandem mass spectrometry were used to identify the product, which was obtained in a yield of 3.5% based on the ratio of His/erythrose. This is a new chemical synthesis of one of the basic amino acids which had not been synthesized prebiotically until now.

Aldehydes↗
PubMed1990

The effects of VDT data entry work on operators.

The before/after study of physiological and biochemical parameters was used to delineate the effects of VDT data entry work on operators. Twenty-nine healthy Chinese students were chosen and divided at random into the simple and the complicated data entry group. The subjects were instructed to work as quickly and correctly as possible according to the 'Data Entry Work Programme' for 150 min. Work performance (correct entry) was automatically recorded once every 10 min. The before/after parameters were tested respectively. The results showed that performance fluctuated over time. It decreased obviously after 50-60 min of work, followed by a rebound, and there was a terminal motivation phenomenon at the end of the test, which was associated with the auto-arousal and cerebral compensatory effort. Changes in physiological parameters revealed that operators were fatigued after data entry work. The adrenaline excretion in urine showed a tendency to increase after simple data entry work. The noradrenaline excretion showed a tendency to decrease after complicated data entry work. The differences in performance, diastolic blood pressure in a standing position and neurobehaviour between two groups indicated that much stress was experienced when performing complicated data entry work.

Adult↗
PubMed1990

Molecular Characterization of the Brittle-2 Gene Effect on Maize Endosperm ADPglucose Pyrophosphorylase Subunits.

Activity of the enzyme ADPglucose pyrophosphorylase is known to be reduced in maize (Zea mays L.) endosperm mutants at two independent loci, Shrunken-2 (Sh(2)) and Brittle-2 (Bt(2)). Spinach leaf ADPglucose pyrophosphorylase has previously been shown to comprise two subunits of 51 and 54 kilodaltons. Anti-bodies raised to each of the two subunits of spinach leaf ADPglucose pyrophosphorylase were found to cross-react to different bands on Western blots prepared from polyacrylamide gel electrophoresis separated wild-type maize endosperm proteins. The anti-spinach leaf 51 kilodalton subunit antibody cross-reacted with a 55 kilodalton maize endosperm protein and the anti-spinach leaf 54 kilodalton subunit antibody cross-reacted with a 60 kilodalton maize endosperm protein. These immunological reactions were observed in maize endosperm extracts and with a highly purified preparation of maize endosperm ADPglucose pyrophosphorylase. Mutant bt(2) endosperm lacked the 55 kilodalton subunit while mutant sh(2) endosperm lacked the 60 kilodalton subunit on Western blots. These results suggest that the maize endosperm ADPglucose pyrophosphorylase is made up of two immunologically dissimilar subunits and that the bt(2) and sh(2) mutations cause reduction in ADPglucose pyrophosphorylase activity through the lack of one of these two subunits. An ADPglucose pyrophosphorylase cDNA clone antigenically selected from a rice seed cDNA expression library was found to hybridize strongly with a cDNA corresponding to a maize endosperm transcript which is absent in a W64A bt(2) mutant. Thus, the bt(2) mutant causes the absence not only of the small subunit but of the corresponding transcript. Bt(2) is implicated as the structural gene for the small (54 kilodalton) subunit of maize endosperm ADPglucose pyrophosphorylase.

Journal Article↗
PubMed1990

Effects of strophanthidin on the slow inward current in guinea-pig isolated ventricular myocytes.

1. The effect of strophanthidin on the slow inward current (Isi) and on contractile force were studied in guinea-pig isolated ventricular myocytes and intact papillary muscles, respectively. In myocytes, both low (10 nmol/L) and high (1-10 mumols/L) concentrations had small or no effects in either direction on Isi whereas norepinephrine (10-100 nmol/L) increased it. To determine whether the same results are obtained after decreasing or increasing intracellular calcium or sodium, the same concentrations of strophanthidin were tested in different procedures that are known to (i) increase [Ca]i and decrease [Na]i (high [Ca]o, 3.6-5.4 mmol/L; low [Na]o, 112 mmol/L; (ii) decrease [Ca]i and increase [Na]i (low [Ca]o, 0.45-1 mmol/L; Sr, 1 mmol/L; (iii) decrease [Ca]i and [Na]i (Cd, 0.1-0.2 mmol/L); and (iv) increase [Ca]i and [Na]i (veratridine, 0.2 mumol/L). High [Ca]o and veratridine increased whereas low [Ca]o and Cd decreased Isi. In contrast, during these various procedures, strophanthidin had small and inconsistent effects at a low or high concentration. In intact papillary muscles, low strophanthidin decreased whereas high strophanthidin increased contractile force. It is concluded that strophanthidin has little direct or indirect effect on Isi and that the decrease in force by low and increase in force by high concentrations in intact muscle are probably related to demonstrated decrease and increase, respectively, in intracellular sodium activity.

Action Potentials↗
PubMed1990

Replication of bovine papillomavirus type 1 DNA initiates within an E2-responsive enhancer element.

When bovine papillomavirus transforms cells in vitro, it maintains its genome as a multicopy nuclear plasmid. Plasmid DNA extracted from such transformed cells was analyzed by the two-dimensional gel electrophoresis technique of Brewer and Fangman (B. Brewer and W. Fangman, Cell 51:463-471, 1987). The replication intermediates detected in these assays were found to be the sums of the oligomeric and monomeric forms of the replicating plasmids. The multimeric DNAs were shown by field inversion gel electrophoresis and partial restriction digestion to be head-to-tail concatemers of the monomeric forms. Furthermore, the multimers progressed in size by steps of one monomer, indicating that they did not arise by replication segregation mistakes of the unit length, which would predict a ladder spaced by integrals of two monomers. To map the plasmid DNA replication origin, the replication intermediates of the monomers were isolated by successive sucrose gradient centrifugation and then examined by the two-dimensional gel electrophoresis method. The patterns detected show that bovine papillomavirus type 1 replicates in these cells bidirectionally and that one replication origin site in the viral genome is utilized. By employing several restriction enzymes and specific viral DNA probes to dissect the replication intermediates, we were able to map the origin of initiation site with some precision. The initiation site, which maps to bovine papillomavirus type 1 DNA position 7730 +/- 100 bp, places the origin within that region of the viral upstream regulatory region which contains the major cluster of transcription factor E2-binding sites, E2RE1. Thus, the actual viral plasmid origin of replication maps near, but outside, genetic elements previously shown to be important for plasmid maintenance.

Animals↗
PubMed1990

[Specific monoclonal antibodies to F41 adhesin of enterotoxigenic Escherichia coli and their potential uses as diagnostic and therapeutic reagents].

A set of hybridoma cell lines, namely, L10, B10, C32, B1, E7, E40 and B49, secreting monoclonal antibodies (MABs) specific to F41 adhesin antigens of ETEC was obtained by somatic hybridization. These MABs manifested strongly specific binding reactivities in DA, ELISA and IFA to all tested F41+ ETEC strains. All these MABs recognized the same or closely related epitopes on the adhesin, as indicated in antigen-competition ELISA with HRP-labeled MABs. The distribution patterns of these epitopes which appeared repeatedly on each pilus were visualized by MAB-immunogold technique and immunoelectron microscopy. The adhesion of ETEC bearing F41 adhesin to the epithelial cells of small intestine from new borne calves and piglets was inhibited in vitro by F41-specific MABs. A dot-immunobinding assay based on F41-specific MABs was developed for determining F41 antigens in fecal samples with HRP-labeled MABs. The assay was highly sensitive and specific, and could be used in rapid detection and screening of F41 adhesin antigens in field samples.

Adhesins, Escherichia coli↗
PubMed1990

[Dissolution of metronidazole stilus].

Metronidazole stilus is a new preparation to be inserted into periodontal pockets for treatment of periodontitis. The certificate and file number of approval given to this new product were issued by the Ministry of Public Health in August, 1989. Its shape looks like a toothpick and the width, thickness and length are 1.5mm, 0.7mm and 3 cm, respectively. The content of metronidazole in each cm of the stilus is 2.2 mg. We have studied the dissolution of the new preparation by rotation basket method. The kinetic process of dissolution approximates first order kinetics. The K, t0.5 and t0.9 are 0.0624 min-1, 12.8 and 38.6 minutes, respectively. The requirement is that the dissolved percentage should not be lower than 60% of the added amount in 30 minutes. In order to have a dissolution test similar to that of the stilus in dental pockets, we examined the dissolution in static condition. The results showed that a very high dissolution rate appeared in the beginning, but it decreased quickly, and 71.76% of metronidazole was not dissolved until 48 hours. So one insertion per two days for clinical use is suggested.

Metronidazole↗
PubMed1990

[Isolation and identification of oral spirochaetes and Fusobacterium in juvenile periodontitis].

Periodontal pocket specimens of 40 juveniles periodontitis (JP) and specimens from gingival sulcus in 40 normal juveniles (NP) were examined. 25 strains of anaerobic oral spirochaete (62.5%) (17 strains were Treponema microdentium, 3 strains macrodentium, 2 strains T orale, 3 strains Borrelia) and 21 strains of fusobacterium were isolated in 40 JP. In 40 NP, 2 strains of spirochaetes (5%) and 3 strains fusobacterium (7.5%) were found. This study shows that there is a relationship between the infection of spirochaeta, fusobacterium and JP.

Adolescent↗
PubMed1990

[HPLC analysis of flavonoids in the root of six Glycyrrhiza species].

Ten flavonoids isolated from six species of Glycyrrhiza root were analysed by reversed phase HPLC. A column packed with Partisil 5 ODS-3 and gradient elution by using different percentage of methanol (B) in water-glacial acetic acid (97:3 V/V) (A) were used to separate licochalcone A, isoschaftoside, schaftoside, liquiritin, isoviolanthin, violanthin, ononin, isoliquiritin, 4', 7-dihydroxyflavone and licoflavone A. Nine Glycyrrhiza samples of six species were analysed to determine their composition and content of the flavonoids. The results showed that the composition and content of the flavonoids of different Glycyrrhiza species were different as well as the same species but collected in different places.

Chromatography, High Pressure Liquid↗
PubMed1990

[Effects of isocorydine on contraction of the rabbit oviduct smooth muscle].

On isolated isthmus of oviduct of the rabbit, Isocorydine (Isoc) (3 mu mol/L) decreased significantly the frequency of spontaneous contraction and muscle tension, but not the amplitude of contraction. The tension and frequency of spontaneous contraction can be suppressed by Isoc at concentrations from 3 to 300 mumol/L. The amplitude of contraction was decreased only at 300 mu mol/L. It is suggested that the frequency and tension of spontaneous contraction of isthmic muscle are more sensitive to Isoc than the amplitude. Isoc antagonized the norepinephrine-induced contraction of the oviduct. The transport of ova through the oviduct reduced by hCG could be delayed by Isoc.

Animals↗
PubMed1990

[Use of derivative UV spectroscopy to monitor the percutaneous absorption of befunolol-HCL].

Second-order derivative UV spectroscopy was used to measure the transfer of befunolol-HCl across full-thickness rabbit skin in vitro. The effect of penetration enhancers, azone-PG and PEG-400, on permeation course of befunolol-HCl was studied. A type of horizontal diffusion cell was employed. Permeability coefficients were measured in normal saline and in solutions containing the enhancing agents. The results indicated that befunolol-HCl may be an interesting candidate for transdermal administration and azone-PG highly and significantly increases the skin permeation of the drug in the solvent system tested.

Administration, Cutaneous↗