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Biomedical subjects

Y Liang

Publications and source records attributed to Y Liang.

At least 199 records · Page 11Linked to original sources
PubMed1999

[The effect of cold- and heat-natured medicines on 5-HT and NE cells and nerve fibres in rat's brain, pituitary and adrenal].

OBJECTIVE: To study how cold- and heat-natured medicines act on 5-HT and NE cells in the brain, pituitary and adrenal of rats. METHOD: Based on immunohistochemical method, the specific anti-TH and anti-5-HT sera were used to observe the changes of 5-HT and NE cells in brain and adrenal as well as fibres in pituitary. The contents of these two transmitters in brain were also determined by fluoriphotometry. RESULTS: Cold-natured medicines made the staining of 5-HT cells deeper and NE cells lighter, while heat-natured medicines act by contraries. CONCLUSION: Cold-natured medicines increase the content of 5-HT in brain and decrease the content of NE, while heat-natured medicines work the other way around. The morphologic changes are consistent with the functional ones.

Adrenal Glands↗
PubMed1999

[Characteristics of outward potassium currents of outer hair cell isolated from the guinea pig cochlea].

OBJECTIVE: To study the normal values and characteristics of potassium currents (Ik) of outer hair cell (OHC) isolated from the guinea pig cochlea. METHOD: With the patch-clamp whole cell recording technique and several supplementary methods, the Ik potassium tail current (Iktail) and reverse potential were recorded under the conditions of the various intra and extracellular solutions and various command voltage stimuli. RESULT: Ik possessed evident voltage and time-dependence. The peak current appeared within 20 ms. The average activated potential was approximately -32.7 mV. Ik increased fastestly and greatestly in the voltage range from the activating voltage to 0 mV, and it approached saturation approximately at 40 mV. In normal status, no distinct "rundown phenomenon" of Ik appeared. When 10 mmol/L KCl was put in extracellular solution, Ik would increased. Nevertheless, when K+ was substituted by Cs+ in the intracellular solution, Ik would disappear. The reversal potential, -64.0 mV in average approximately, could be measured by means of Iktail. Furthermore, by means of slope command voltage stimuli, the processes of Ik activation, increment or decrement and saturation could be observed. CONCLUSION: As showing by the above described features, Ik possessed the characteristics of both an inward rectifier and rapid element of a delay rectifier, which would play important role in frequency tuning, mechanic-electrical transduction, maintenance of resting potential and excitement in OHC.

Animals↗
PubMed1999

[Experience in endoscopic sinus surgery in district hospital].

OBJECTIVE: To explore the importance and specificity of conducting endoscopic sinus surgery (ESS) in district hospital. METHOD: Seventy patients with chronic nasal sinusitis or/and nasal polyps undergone ESS from June 1997 to October 1998 were retrospectively analyzed. The curative effect was evaluated according as FESS-95 Guangzhou Standard. RESULT: In all patients, 52 cases (74.3%) were cured, 16 cases (22.9%) improved, 2 cases (2.8%) unimproved and 4 cases (5.7%) were found with complications. CONCLUSION: The results showed that intranasal endoscopic sinus surgery had a significant effect on treating nasal-sinusitis and nasal polyps. The CT types of ethmoid sinus are significant in selecting anesthesia and operation program. To get a good result, a full combined therapy in the perioperation period and a careful endoscopic follow-up postoperation are important.

Adolescent↗
PubMed1999

[Analysis of HPLC of isomers of nitrotoluene and nitrobenzoic acid].

Nitrotoluene and nitrobenzoic acid isomers were separated completely in less than 10 minutes by Kromasil C18 (200 mm x 4.6 mm i.d.), when V(CH3OH):V(H2O):V(THF) = 55:44:1 with beta-CD of 0.02 mol/L at flow rate of 2.0 mL/min (former 4 min) and 2.6 mL/min (later 6 min). Detector of UV-254 at 0.04 AUFS was used.

Chromatography, High Pressure Liquid↗
PubMed1999

[Effects of sodium salicylate on outward potassium current, resting potential and membrane electric capacitance of the outer hair cell isolated from guinea pig cochlea].

OBJECTIVES: To study effects of sodium salicylate on the outward potassium current (IK), resting potential (RP) and membrane electric capacitance (MEC) of outer hair cells isolated from guinea pig cochleas and the cytoelectrophysiological mechanisms of effects of sodium salicylate on functions of hair cells. METHODS: Using the patch-clamp whole cell recording technique, IK, RP and MEC were measured before and after the administration of sodium salicylate at concentration of 0.1 or 1.0 mmol/L. The effects of sodium salicylate on IK, RP and MEC were observed. RESULTS: The effects of sodium salicylate on IK had time- and dosage-effect relations, of which the former mean IK increasing and then decreasing after administration, the later meant that the effects of sodium salicylate being much more dominant during either increasing or decreasing IK in higher concentration than in lower concentration. The mean RP was approximately--60 mV and the mean MEC was approximately 39 pF. Sodium salicylate could decrease RP and MEC, which possessed a dosage-effect relation, that is, the effect was stronger in higher concentration than in lower concentration, and there was no clear evidence for time-effect relation. CONCLUSIONS: The sodium salicylate might affect the K+ conduction at the lateral membrane and internal and external distribution of K+ in the outer hair cell. Sodium salicylate might affect the excitability and mechanical activity of the outer hair cell by means of affecting IK, RP and MEC, which might be one of the cochlear mechanisms of the effects of sodium salicylate on the functions of hair cells.

Animals↗
PubMed1999

[UV-Vis spectroscopic characterization of LB films of hydroxyl-substituted porphyrin derivatives].

The LB films forming properties of two hydroxyl-substituted porphyrins with double hexadecyl chains have been characterized. UV-Vis spectra show that the two porphyrins possess various aggregation behaviors in LB films. The porphyrin with symmetrically attached chains tend to form J-aggregate and the other asymmetric porphyrin can form hydrogen-bonded aggregate in LB films. The orientation of porphyrin rings was examined by polarized UV-Vis spectra. The results indicate that the situation of side-chain attached on porphyrin ring has no influence on porphyrin ring orientation, but has great influence on mean molecular areas or the distanses between porphyrin rings, and so as to affect the aggregation behaviors of porphyrin in LB films.

Molecular Structure↗
PubMed1999

[Study on the determination method of Mo in the internal organs of body by graphite furnace atomic absorption spectrophotometry].

A new method for the determination of Mo in the heart by tantalum-lining graphite tube was developed. The tantalum-lining graphite tube can entirely eliminate effects of stable carbide formed. The sensitivity was enhanced to compare with the conventional graphite tube. At the same time, it also climinates memory effect completely and reduces the interferences of coexistent elements such as Fe, Na, K etc. The method is simple, accurate and rapid.

Humans↗
PubMed1998

Stability studies of tetracycline in methanol solution.

The stability of tetracycline in methanol solution was investigated by UV-visible spectroscopy, HPLC and TLC methods. After dissolution in methanol, tetracycline decomposed rapidly under the influence of light and atmospheric oxygen, forming more than fourteen different degradation products. None of the previously reported degradation products, such as the epi- and anhydro-compounds, were detected as the final degradation products. The molecular structures for eight of the compounds were suggested by their product-ion mass spectra. A degradation sequence was proposed for the reactions of tetracycline with methanol. A new HPLC-MS mobile phase was developed, which solved the clogging problem at the interface between the HPLC and MS chamber and enabled a high separation efficiency.

Chromatography, High Pressure Liquid↗
PubMed1998

FTIR and UV-Vis Spectroscopic Studies of Black Soap Film.

FTIR and UV-vis spectroscopies have been employed to investigate the self-assembly features of a black soap film (BSF) prepared from aqueous solution consisting of 10(-2) M cetyltrimethylammonium bromide (CTAB) and 10(-3) M thiazole yellow (TY) in the liquid-crystalline and gel states, respectively. The construction of two surfactant monolayers of the soap film is independent of the thickness of aqueous core, and the thickness is approximately 1.7 nm at equilibrium. In the liquid-crystalline state, the methylene segments of the hydrocarbon chains are averagely oriented at an angle of 70 degrees with respect to the film normal, and the alkyl chains take a long-range interaction to improve the film elasticity. The TY molecules in the film are horizontally aligned at the monolayer interface in the J-aggregate form. The double-negatively charged TY aggregate greatly enhances the film stability. Dye neutral red is further introduced into the CTAB soap film, the film lifetime is related to the type of the added dyes, in the order of cationic < nonionic < anionic. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Dopamine agonist treatment ameliorates hyperglycemia, hyperlipidemia, and the elevated basal insulin release from islets of ob/ob mice.

One of the characteristics of obesity-associated diabetes is an elevated fasting plasma insulin concentration with a weak insulin secretory response to subsequent glucose stimulation. Evidence suggests that hyperglycemia and hyperlipidemia may contribute to the initiation and progression of this disordered islet glucose sensing. It has been proposed that reducing hyperglycemia and hyperlipidemia per se may improve islet glucose sensing. Here we studied glucose-dependent insulin release in islets isolated from ob/ob mice treated with dopamine agonists (bromocriptine and SKF38393, BC/SKF) which significantly reduced circulating glucose and lipid levels of ob/ob mice. Islets from BC/SKF-treated mice showed a marked decrease of the elevated basal insulin release to levels similar to lean mice. Such treatment also induced a higher secretory response to glucose stimulation compared with that in ob/ob mice with sustained hyperglycemia and hyperlipidemia. Similarly, when islets from untreated ob/ob mice were cultured for 7 days in 11 mM glucose in the absence of free fatty acid, the basal insulin release was significantly decreased and high glucose stimulated insulin release increased compared with that from islets cultured in medium containing 30 mM glucose and 2 mM oleate. The BC/SKF-induced reduction of elevated basal insulin release was associated with decreased hexokinase activity and basal cyclic AMP content in islet tissue. Our results demonstrate that dopamine agonist treatment improves basal insulin release in ob/ob mice and this effect may be mediated, in part, by a reduction of hyperglycemia and hyperlipidemia.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1998

The presenilin 1 protein is a component of a high molecular weight intracellular complex that contains beta-catenin.

The presenilin (PS) genes associated with Alzheimer disease encode polytopic transmembrane proteins which undergo physiologic endoproteolytic cleavage to generate stable NH2- and COOH-terminal fragments (NTF or CTF) which co-localize in intracellular membranes, but are tightly regulated in their stoichiometry and abundance. We have used linear glycerol velocity and discontinuous sucrose gradient analysis to investigate the distribution and native conformation of PS1 and PS2 during this regulated processing in cultured cells and in brain. The PS1 NTF and CTF co-localize in the endoplasmic reticulum (ER) and in the Golgi apparatus, where they are components of a approximately 250-kDa complex. This complex also contains beta-catenin but not beta-amyloid precursor protein (APP). In contrast, the PS1 holoprotein precursor is predominantly localized to the rough ER and smooth ER, where it is a component of a approximately 180-kDa native complex. PS2 forms similar but independent complexes. Restricted incorporation of the presenilin NTF and CTF along with a potentially functional ligand (beta-catenin) into a multimeric complex in the ER and Golgi apparatus may provide an explanation for the regulated accumulation of the NTF and CTF.

Alzheimer Disease↗
PubMed1998

Proteolytic processing of rubella virus nonstructural proteins.

The genomic RNA of rubella virus contains two long open reading frames (ORF), a 5'-proximal ORF that codes for the nonstructural proteins and a 3'-proximal ORF that encodes the structural proteins. The cDNA encoding the nonstructural protein ORF of the wild-type M33 strain of rubella virus has been obtained and sequenced. Comparison between the nonstructural proteins of the M33 and Therien strains of rubella virus revealed a 98% homology in nucleotide sequence and 98.1% in deduced amino acid sequence. To examine the processing of rubella virus nonstructural protein, the complete nonstructural protein ORF was expressed in BHK cells using a pSFV expression vector. Three nonstructural protein products (p200, p150, and p90) with molecular weights of 200, 150, and 90 kDa were identified using antisera raised against synthetic peptides corresponding to regions of the nonstructural proteins. p200 is the polyprotein precursor, while p150 and p90 are the cleavage products. Site-directed mutagenesis of the Cys-1151 residue (one of the catalytic dyad residues of the viral protease) and of the Gly-1300 residue (the viral protease cleavage site) abrogated protease activity and p200 precursor cleavage, respectively. Coexpression of mutant constructs in BHK cells indicated that rubella virus protease can function both in cis and in trans.

Animals↗
PubMed1998

Effect of risk factors on the mechanism of acute thrombosis and sudden coronary death in women.

BACKGROUND: Traditional risk factors have been linked to atherosclerotic heart disease in women. However, the effect of risk factors and menopausal status on the mechanism of sudden coronary death is unknown. METHODS AND RESULTS: We examined 51 cases of sudden coronary death and 15 hearts from women who died of trauma. Coronary deaths were divided into four mechanisms of death: ruptured plaque with acute thrombus (n = 8), eroded plaque with acute thrombus (n = 18), stable plaque with healed infarct (n = 18), and stable plaque without infarction (n = 7). Vulnerable plaques prone to rupture were defined as those with a thin, fibrous cap infiltrated by macrophages and were quantitated in coronary deaths and control subjects. Total cholesterol (TC), HDL cholesterol, glycosylated hemoglobin, cigarette smoking, and hypertension were determined in each case. Compared with control subjects, women with plaque ruptures had elevated TC (270 +/- 55 versus 194 +/- 44 mg/dL, P = 0.002), and those with erosions were more likely to be smokers (78% versus 33%, P = 0.01). Women with stable plaque and healed infarct had elevated glycosylated hemoglobin (10.2 +/- 5.0% versus 6.4 +/- 0.4% in control subjects, P = 0.001) and were more likely to be hypertensive (50% versus 15% in control subjects, P = 0.03). By multivariate analysis, cigarette smoking was associated with plaque erosion (P = 0.03, odds ratio [OR] 21), glycoslyated hemoglobin with stable plaque and healed infarct (P = 0.03, OR 41), TC with plaque rupture (P = 0.02, OR 7), and hypertension with stable plaque with healed infarct (P = 0.02, OR 15). Seven of 8 plaque ruptures occurred in women > 50 years of age versus 3 of 18 erosions (P = 0.001). In cases of coronary death, vulnerable plaques were associated with elevated cholesterol (P = 0.002) and age > 50 years (P = 0.002), independent of other risk factors. CONCLUSIONS: In women, traditional risk factors have distinct effects on the mechanisms of sudden coronary death, which vary by menopausal status. Effective risk factor modification may therefore differ between younger and older women and may be targeting different mechanisms of plaque instability.

Acute Disease↗
PubMed1998

Correction of deafness in shaker-2 mice by an unconventional myosin in a BAC transgene.

The shaker-2 mouse mutation, the homolog of human DFNB3, causes deafness and circling behavior. A bacterial artificial chromosome (BAC) transgene from the shaker-2 critical region corrected the vestibular defects, deafness, and inner ear morphology of shaker-2 mice. An unconventional myosin gene, Myo15, was discovered by DNA sequencing of this BAC. Shaker-2 mice were found to have an amino acid substitution at a highly conserved position within the motor domain of this myosin. Auditory hair cells of shaker-2 mice have very short stereocilia and a long actin-containing protrusion extending from their basal end. This histopathology suggests that Myo15 is necessary for actin organization in the hair cells of the cochlea.

Amino Acid Sequence↗
PubMed1998

Association of unconventional myosin MYO15 mutations with human nonsyndromic deafness DFNB3.

DFNB3, a locus for nonsyndromic sensorineural recessive deafness, maps to a 3-centimorgan interval on human chromosome 17p11.2, a region that shows conserved synteny with mouse shaker-2. A human unconventional myosin gene, MYO15, was identified by combining functional and positional cloning approaches in searching for shaker-2 and DFNB3. MYO15 has at least 50 exons spanning 36 kilobases. Sequence analyses of these exons in affected individuals from three unrelated DFNB3 families revealed two missense mutations and one nonsense mutation that cosegregated with congenital recessive deafness.

Amino Acid Sequence↗
PubMed1998

Structural characterization of the virB operon on the hairy-root-inducing plasmid A4.

The hairy-root-inducing plasmid A4 (pRiA4) is capable of conferring tumorigenic symptoms on plants upon infection by its host bacterium, Agrobacterium rhizogenes. The virB operon on pRiA4 has been sequenced and found to be composed of 11 genes, virB1 to virB11, whose products mostly appear to be associated with the cell membrane. A novel structural characteristic is frequent overlappings between the translation termination and initiation codons of adjacent genes. This is indicative of fine tuning of relative translation frequencies for each VirB protein. These results support the view that VirB multisubunit complexes provide facilities for T-DNA transfer at the bacterial cell membrane. The structural organization of the pRiA4 virB operon was essentially identical to that of the previously reported virB operons of tumor-inducing plasmids, pTiC58 and pTiA6, and the corresponding VirB proteins of the three plasmids were extremely homologous to one another. On the basis of the structural similarity of each VirB protein, the phylogenetic relationship among pRiA4, pTiC58, and pTiA6 is discussed.

Bacterial Proteins↗
PubMed1998

Use of high-precision gas isotope ratio mass spectrometry to determine natural abundance 13C in lutein isolated from C3 and C4 plant sources.

A method was developed for high-precision stable carbon isotope ratio analysis of lutein isolated from a C3 (marigold flower) and a C4 (corn gluten meal) plant source using gas chromatography-combustion interfaced isotope ratio mass spectrometry. The natural abundance of 13C (expressed as delta 13C versus the international standard, Pee Dee Belemnite, in per mil units, denoted /1000) in lutein isolated from marigold flower and corn gluten meal was determined to be -29.90 +/- 0.20/1000 and -19.77 +/- 0.27/1000 (mean +/- S.D.), respectively. The high precision of gas isotope ratio mass spectrometry is potentially applicable to detect differences of isotopic composition of lutein in the blood, tissues, or excreta of animal models or humans that result from differences in the natural abundance of 13C in C3 and C4 plant foods.

Carbon Isotopes↗