Search PubMed⌕ Search

Biomedical subjects

Y Liang

Publications and source records attributed to Y Liang.

At least 145 records · Page 8Linked to original sources
PubMed2000

Stimulated orientational and thermal scatterings and self-starting optical phase conjugation with nematic liquid crystals

A quantitative theory and experimental results on self-starting optical phase conjugation, using stimulated orientational and thermal scattering in nematic liquid crystal films, are presented. The coupled wave-material equations for the laser-induced refractive index changes, grating formation, and coherent wave mixing effects are developed. Analytical solutions are obtained for the case of negligible pump depletion, and numerical solutions for various input and generated signals, taking losses into account, are obtained. Experimentally, we demonstrate the feasibility of realizing these stimulated scattering and phase conjugation processes in thin (200 &mgr;m) nematic liquid crystal with a milliwatt-power cw laser. Theoretical estimates for various gain constants and threshold intensities, and their dependence on various physical parameters, are found to be in good agreement with experimental observations.

Journal Article↗
PubMed2000

Mutational analysis of the rubella virus nonstructural polyprotein and its cleavage products in virus replication and RNA synthesis.

Rubella virus nonstructural proteins, translated from input genomic RNA as a p200 polyprotein and subsequently processed into p150 and p90 by an intrinsic papain-like thiol protease, are responsible for virus replication. To examine the effect of p200 processing on virus replication and to study the roles of nonstructural proteins in viral RNA synthesis, we introduced into a rubella virus infectious cDNA clone a panel of mutations that had variable defective effects on p200 processing. The virus yield and viral RNA synthesis of these mutants were examined. Mutations that completely abolished (C1152S and G1301S) or largely abolished (G1301A) cleavage of p200 resulted in noninfectious virus. Mutations that partially impaired cleavage of p200 (R1299A and G1300A) decreased virus replication. An RNase protection assay revealed that all of the mutants synthesized negative-strand RNA as efficiently as the wild type does but produced lower levels of positive-strand RNA. Our results demonstrated that processing of rubella virus nonstructural protein is crucial for virus replication and that uncleaved p200 could function in negative-strand RNA synthesis, whereas the cleavage products p150 and p90 are required for efficient positive-strand RNA synthesis.

Animals↗
PubMed2000

Rubella virus nonstructural protein protease domains involved in trans- and cis-cleavage activities.

Rubella virus (RV) genomic RNA contains two large open reading frames (ORFs): a 5'-proximal ORF encoding nonstructural proteins (NSPs) that function primarily in viral RNA replication and a 3'-proximal ORF encoding the viral structural proteins. Proteolytic processing of the RV NSP ORF translation product p200 is essential for viral replication. Processing of p200 to two mature products (p150 and p90) in the order NH(2)-p150-p90-COOH is carried out by an RV-encoded protease residing in the C-terminal region of p150. The RV nonstructural protease (NS-pro) belongs to a viral papain-like protease family that cleaves the polyprotein both in trans and in cis. A conserved X domain of unknown function was found from previous sequence analysis to be associated with NS-pro. To define the domains responsible for cis- and trans-cleavage activities and the function of the X domain in terms of protease activity, an in vitro translation system was employed. We demonstrated that the NSP region from residue 920 to 1296 is necessary for trans-cleavage activity. The domain from residue 920 to 1020 is not required for cis-cleavage activity. The X domain located between residues 834 and 940, outside the regions responsible for both cis- and trans-cleavage activities of NS-pro, was found to be important for NS-pro trans-cleavage activity but not for cis-cleavage activity. Analysis of sequence homology and secondary structure of the RV NS-pro catalytic region reveals a folding structure similar to that of papain.

Amino Acid Sequence↗
PubMed2000

Chronic infusion of norepinephrine into the VMH of normal rats induces the obese glucose-intolerant state.

Increases in ventromedial hypothalamic (VMH) norepinephrine (NE) levels and/or activities have been observed in a variety of animal models of the obese insulin-resistant condition. This study examined the metabolic effects of chronic NE infusion (25 nmol/h) into the unilateral VMH of normal rats. Within 4 days, VMH NE infusion significantly increased plasma insulin (140%), glucagon (45%), leptin (300%), triglyceride (100%), abdominal fat pad weight (50%), and white adipocyte lipogenic (100%) and lipolytic (100%) activities relative to vehicle-infused rats. Furthermore, isolated islet insulin secretory response to glucose (15 mM) within 4 days of such treatment was increased over twofold (P < 0.05). Among treated animals, fat stores continued to increase over time and plateaued at approximately 2 wk (3-fold increase), remaining elevated to the end of the study (5 wk). By week 4 of treatment, NE infusion induced glucose intolerance as evidenced by a 32% increase in plasma glucose total area under the glucose tolerance test curve (P < 0.01). Whole body fat oxidation rate measured after 5 wk of infusion was significantly increased among treated animals as evidenced by a reduced respiratory quotient (0.87 +/- 0.01) relative to controls (0. 90 +/- 0.01). VMH NE infusion induced hyperphagia (30%) only during the first week and did not affect body weight over the 5-wk period. Increases in VMH NE activity that are common among obese insulin-resistant animal models can cause the development of this obese glucose-intolerant (metabolic) syndrome.

Adipose Tissue↗
PubMed2000

Large-scale cDNA analysis reveals phased gene expression patterns during preimplantation mouse development.

Little is known about gene action in the preimplantation events that initiate mammalian development. Based on cDNA collections made from each stage from egg to blastocyst, 25438 3'-ESTs were derived, and represent 9718 genes, half of them novel. Thus, a considerable fraction of mammalian genes is dedicated to embryonic expression. This study reveals profound changes in gene expression that include the transient induction of transcripts at each stage. These results raise the possibility that development is driven by the action of a series of stage-specific expressed genes. The new genes, 798 of them placed on the mouse genetic map, provide entry points for analyses of human and mouse developmental disorders.

Animals↗
PubMed2000

Peroxisomes in permanent and provisional kidneys. Phylogenic and ontogenic considerations.

Peroxisomes in three forms of vertebrate kidney (pronephros, mesonephros, and metanephros), as permanent or provisional kidney, are summarized concerning their ultrastructure and developmental changes. Because the peroxisome is known to be diverse in mammalian metanephros, and species difference is its distinctive feature among cell organelles, information should be obtained on each kidney of each species. The ultrastructural and biochemical features of peroxisomes have at least been partly delineated in the metanephros and mesonephros, but nothing is known about the pronephros. Ultrastructural studies of the metanephric peroxisomes are present in mammals, birds, and reptiles, but information on their development is restricted to mammals and birds. As for the mesonephric peroxisomes, both ultrastructural and developmental data have been accumulating on mammals and amphibians, and ultrastructural information is present on fishes, but not on birds and reptiles. At present, studies on peroxisomes of provisional kidney have been restricted to mammalian mesonephros. The common features of renal peroxisomes previously examined are that they are spherical cell organelles with a single limiting membrane in ultrastructure, and are positive for catalase. Information on the ultrastructure and enzymes is not sufficient at present for comparing the ontogenesis of renal peroxisomes with their phylogenesis.

Animals↗
PubMed2000

Therapeutic drug monitoring of paclitaxel (Zisu) in cancer patients.

We monitored the therapeutic drug paclitaxel (Zisu) and studied its anticancer activity and side effects in 11 cancer patients. After intravenous infusion of 135 to 185 mg/m2 of paclitaxel, Cmax ranged from 2.17 to 9.17 mg/L and AUC ranged from 4.37 to 16.01 mg/h/L. A significant individual difference in pharmacokinetic parameters was found. Among the 11 patients, 6 achieved a partial remission and one patient had a mild response. The Cmax of the patients who achieved PR and MR was higher in comparison to the patients with no response. In 4 of the 6 PR patients, Cmax was above 4.38 mg/L. In four of the NR patients, Cmax was equal to or below 4.04 mg/L. These results suggested a relationship between Cmax and the cancer response rate. No significant relationship could be found between Cmax and the nadir of the white blood cells and platelets.

Adult↗
PubMed2000

Neurochemical and cellular markers in human cervix of late pregnant, postpartal and non-pregnant women.

BACKGROUND: The aim was to evaluate the peptidergic innervation and the dendritic cell content in the cervix uteri. METHODS: Cervical biopsies were obtained from late pregnant (n=5), postpartal (n=5) and non-pregnant (n=5) women. The samples were prepared for immunohistochemistry using antibodies to protein S-100 (S-100), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), human peptide histidine isoleucine amide (PHM 27), neuropeptide tyrosine (NPY), and human histocompatibility complex class II subregion DR (HLA-DR). RESULTS: Nerve fibers positive for protein S-100, and dendritic cells positive for S-100 and HLA-DR were abundant in the cervix, especially at late pregnancy. CGRP, VIP, PHM-27 and NPY positive nerve fibers were present in non-pregnant, short nerve fibers and scattered immunoreactivity at term, and further scattered immunoreactivity after parturition. NPY positive nerve fibers were decreased at term, and after parturition a scattered immunoreactivity was observed. CONCLUSIONS: The abundant protein S-100 positive nerve fibers implies an impact of myelinated nerves in the cervix uteri during pregnancy. The abundant dendritic cells, positive for HLA-DR and S-100, especially at term, indicates a general activation of the immune system until late pregnancy and parturition. The changed occurrence and distribution of immunoreactivity for CGRP, VIP and PHM-27 suggest a release of these neuropeptides until term. The changes in NPY immunoreactivity indicate a release of NPY around parturition.

Adult↗
PubMed2000

Frontotemporal dementia with novel tau pathology and a Glu342Val tau mutation.

It is unclear how tau gene mutations cause frontotemporal dementia (FTD) with parkinsonism linked to chromosome 17 (FTDP-17), but those in exon 10 (E10) or the following intron may be pathogenic by altering E10 splicing, perturbing the normal 1:1 ratio of four versus three microtubule-binding repeat tau (4R:3R tau ratio) and forming tau inclusions. We report on a 55-year old woman with frontotemporal dementia and a family history of FTDP-17 in whom we found a novel E12 (Glu342Val) tau gene mutation, prominent frontotemporal neuron loss, intracytoplasmic tau aggregates, paired helical tau filaments, increased 4R tau messenger RNA, increased 4R tau without E2 or E3 inserts, decreased 4R tau with these inserts, and a 4R:3R tau ratio greater than 1 in gray and white matter. Thus, this novel Glu342Val mutation may cause FTDP-17 by unprecedented mechanisms that alter splicing of E2, E3, and E10 to preferentially increase 4R tau without amino terminal inserts and promote aggregation of tau filaments into cytopathic inclusions.

Brain↗
PubMed2000

[The clinical application of the reverse island skin flap supplied by the superficial sural artery].

OBJECTIVE: To conform the reliability of the reverse island skin flap supplied by the superficial sural artery in clinical applications. METHODS: The distally based superficial sural artery flap was designed on the posterior aspect of the leg. 15 patients were treated with this flap, who had soft-tissue shortage of the lower third of the leg, the foot or the heel. The size of the flap ranged from 10 cm x 8 cm to 5 cm x 4 cm. RESULTS: All flaps survived. The results were satisfactory after 6 to 18 months' postoperative follow-up. CONCLUSIONS: The blood supply of this flap is reliable without sacrificing the major arteries. Flap elevation is easy and quick. This flap may provide a new method in reconstructioning the soft-tissue shortage of the lower leg, the foot and the heel.

Adolescent↗
PubMed2000

[Wang Yinglin and his answer to the questions of a Korean physician].

The book named Da Chaoxianyi Wen (Answer to the Questions of a Korean Physician), written in 1624, recorded the written answers of Wang Yinglin, a Chinese official in the Ming dynasty, to the questions of Yin Zhiwei, a Korean official physician. The 24 A&Qs concerned about the therapy of ordinary diseases, channels and the theories of TCM, etc. The study of this book could not only clarify various questions on the exchanges between Wang and Yin, but also learn more information on the development of Korean medicine at that time.

Books↗
PubMed2000

Effects of endothelin B receptor antagonists, BQ788 and ET-1(11-21) fragment on the bronchoconstriction elicited by isocapnic hyperpnea in guinea pigs.

OBJECTIVE: To explore the role of endothelin (ET) in the pathogenesis of exercise-induced asthma (EIA), we investigated the effects of ETB receptor antagonists, ET-1(11-21) fragment and N-cis-2, 6-dimethylpiperidinocardonyl-L-gamma-methylleucyl-D-1-methoxycarbonyl tryptophanyl-D-norleucine (BQ788) on bronchoconstriction elicited by isocapnic hyperpnea in guinea pigs. METHODS: Eighteen pathogen-free Hartley guinea pigs were randomly divided into three groups. A: normal saline (NS) inhalation control group (n = 6), B: BQ788 group (n = 6), and C: ET-1(11-21) fragment group (n = 6). Guinea pigs were anesthetized with pentobarbital sodium. After measuring the basal value of lung resistance (RL) and dynamic compliance of the respiratory system (Cdyn), NS (0.96 ml), BQ788 (9 nmol) and ET-1(11-21) fragment (9 nmol) were inhaled. A rodent respirator with a dry 5% CO(2)-95% O2 mixture at room temperature provided mechanical ventilation (VT8 ml/animal, 100 breaths/min) for 5 min. RL and Cdyn of the 3 groups were measured again after isocapnic hyperpnea challenge. RESULTS: In the control group, isocapnic hyperpnea of dry gas elicited a marked increase in RL and decrease in Cdyn. RL and Cdyn of the guinea pigs from BQ788 group and ET-1(11-21) fragment group did not change significantly. CONCLUSION: It was demonstrated that selective ETB receptor antagonists, ET-1(11-21) fragment and BQ788, inhibited the bronchoconstriction induced by isocapnic hyperpnea in guinea pigs. The data showed that ETs are potent constrictors of guinea pig airway smooth muscle via a direct effect on ET receptors. It was suggested that ET receptor antagonists, especially ETB receptor antagonist, might be beneficial in preventing EIA.

Airway Resistance↗
PubMed2000

[Assessment of treatment regimens in 58 cases with acute pulmonary embolism].

OBJECTIVE: To explore the best regimen of treatment for acute pulmonary embolism(APE), and to evaluate the efficacy and safety of 2-h infusion of recombinant tissue-type plasminogen activator, Alteplase (rt-PA) and urokinase(UK). METHODS: Fifty-eight patients with APE diagnosed by perfusion lung scanning (ECT) or angiography(CPA) were treated with different regimens: i.e. 2-h infusion of rt-PA or UK (2-h group); low doses of UK for 3-7 days (Qd group); anticoagulants alone and thromboectomy. The results were compared. RESULTS: Of the 41 patients treated with thrombolytic therapy 78% showed improvement in lung perfusion scan and clinical presentation without severe adverse effects, the percentage was significantly higher than that of the anticoagulant group(P < 0.001). The rate of improvement was 84% if thrombolytic therapy was given in 2 h. The mortality rate was lower than anticoagulants and thromboectomy group. The success rate of thromboectomy was 40%. CONCLUSIONS: A 2 h regimen of rt-PA or UK showed reliable efficacy and safety for treatment of APE. The indication of thrombolytic therapy can be extended. Mortality and morbidity could be reduced if thrombolytic therapy followed by anticoagulation is applied as early as possible.

Acute Disease↗
PubMed2000

[The extent of paradoxical thoracoabdominal motion during exercise was improved with oxygen therapy in patients with stable moderate to severe chronic obstructive pulmonary disease].

OBJECTIVE: To assess the synergetic change of thoracoabdominal motion in COPD patients during incremental exercise testing, and to evaluate the effect of oxygen therapy on thoracoabdominal synergetic motion. METHODS: 30 stable moderate to severe COPD patients performed incremental exercise test with ergometer twice while breathing either air or 30% oxygen. Thoracoabdominal motion (assessed by TCD/VT) was monitored with respigraph during the whole test. RESULTS: 18 of 30 patients had TCD/VT > 1.20 during maximal exercise. TCD/VT at maximal exercise (TCD/VTmax) was significantly correlated with FEV1, FVC, MVV and PaCO2(r = -0.66, -0.63, -0.51, and 0.51), but not correlated with DLCO. The thoracoabdominal synergetic motion could be obviously improved with oxygen therapy. CONCLUSIONS: The change of thoracoabdominal synergetic motion during exercise in COPD patients was related with ventilatory function and blood gases. Oxygen therapy could obviously ameliorate paradoxical thoracoabdominal motion.

Abdomen↗
PubMed2000

[Mechanisms of bone repairment in periapical diseases: studies on adjusting bone metabolism with calcium hydroxide in vitro].

OBJECTIVE: To provide experiment evidence for clinical practice and for further exploration on mechanism and medicinal control of periapical diseases. METHODS: The culture model of neonatal mouse calvariae which has the similar biological activity to alveolar bone was established in vitro to observe the influence of calcium hydroxide on osteo-activity. RESULTS: The results showed that calcium hydroxide with proper concentration at organ culture level could enhance osteoblast ALP secreting activity, and increased the tendency of bone formation. At the same time, the concentration of inorganic PO4(3-) in culture medium also had significant changes. CONCLUSIONS: The mechanism of calcium hydroxide promoting repairment of bone tissues is not only by providing rich Ca2+ and alkaline environment mineral deposition, but also by stimulating calcification enzyme activity of osteoblast. Meanwhile, increased PO4(3-) concentration might improve the mineralization environment, which causes mineralization easily.

Alkaline Phosphatase↗
PubMed2000

[Effect of Digan oral liquid on thymic lymphocyte proliferation cycle in immune mediated aplastic anemia in mice].

OBJECTIVE: To study the effect of Digan oral liquid (DGOL) on cell proliferation cycle of thymic lymphocyte in immune mediated aplastic anemia (IMAA) in mice. METHODS: Balb/c mice were used in the experiment, after having exposed under a sublethal amount of radiation, the mice were received injection of mixed cells of thymus and lymph node of DBA/2 mice to form the IMAA models. The model mice were grouped and treated, then their thymus was taken to prepare the single cell suspension for analysis by flow cytometry. RESULTS: Majority of thymocyte of IMAA mice stopped at the G0/G1 phase, and the cells in S and G2 + M phases were significantly less than those in the normal control group, P < 0.01. Both DGOL and Siwu oral liquid could increase the differentiation and proliferation of thymocytes and reduce the apoptosis rate of them, but DGOL showed a better effect, P < 0.05. CONCLUSION: DGOL could significantly promote the differentiation and proliferation of thymocytes and reduce the apoptosis rate of them in IMAA mice, the effect of its is superior to that of Siwu oral liquid.

Anemia, Aplastic↗
PubMed2000

[The prevention of infection complicating acute necrotizing pancreatitis:an experimental study].

OBJECTIVE: To observe the effects of 5 intervention measures on infection complicating acute necrotizing pancreatitis (ANP) in dogs and rats. METHODS: A lethal model of ANP was reproduced by infusion of artificial bile into the biliopancreatic duct. Animals were divided randomly into: ANP group (no treatment); Chinese medicine group ("Qing Yi Tang"); Bifidobacterium mixture group; purgation group (MgSO(4)); selective decontamination of the digestive tract (SDD) group; and somatostatin group. The pancreas and intestine were observed morphologically and tight junction on ileum epithelia was assessed on cryofracture replicas. Blood and/or tissue levels of DAO and D-lactic acid and uric contents of lactulose/mannitol (L/M), served as indicators of gut barrier function, were measured at various time points. Intestinal flora and incidence of bacterial translocation (BT) to organs were examined. RESULTS: In early stage of ANP, mucosal and epithelial tight junction damage and flora disturbance occurred in the gut. In addition, the gut barrier function indicators deteriorated. The BT rates were as high as 78.6% (canine) and 59.5% (rat). Treatment with Chinese medicine markedly improved gut barrier function and reduced BT rate (32.1% - 37.0%). Having similar purgative response as Chinese medicine, MgSO4 did not show any beneficial effect on gut barrier protection and the incidence of BT was not reduced. In bifidobacterium mixture and SDD group, flora balance was preserved well and similar results as Chinese medicine were obtained. The BT rates of these two groups decreased to 33.9% and 33.3%, respectively. Somatostatin markedly blunted pancreatic tissue injury and ameliorated gut barrier damage during early phase of ANP. All intervention measures except for purgation also decreased mortalities (14.3% - 35.3%, compared with 58.8% of the no treatment group). CONCLUSIONS: Treatment with Chinese medicine, bifidobacterium mixture, SDD and somatostatin attenuated gut barrier damage and BT after ANP, and could be used to prevent secondary infection after ANP, but purgation alone is not effective.

Animals↗