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S Liu

Publications and source records attributed to S Liu.

At least 721 records · Page 40Linked to original sources
PubMed1997

[Artificial neural network applied for spectral overlap interference correction in ICP-AES].

A back-propagation artificial neural network (BP-ANN) has been applied to correcting spectral overlap interference in inductively coupled plasma atomic emission spectrometry (ICP-AES). Some network parameters including the range of input values and training sequence for training patterns presented to the network were discussed using simulated Ce 413.380nm and Pr 413.380nm line profiles. Results show that the noise in simulated mixture spectra will slow down the network convergence and has more influence on network prediction.

Neural Networks, Computer↗
PubMed1997

Oxidative modification of low density lipoprotein in normal and hyperlipidemic patients: effect of lysophosphatidylcholine composition on vascular relaxation.

The elevated level of plasma low density lipoprotein (LDL) in hyperlipidemic patients is an important risk factor for the production of atherosclerosis. Plasma LDL must be modified before it can produce an impairment of endothelium-dependent relaxation in aortic rings or enhancement of uptake by macrophages. The dramatic increase in lysophosphatidylcholine (lysoPC) content in oxidatively modified LDL has been touted as an important biochemical factor for the impairment of endothelium-dependent relaxation. The present study was designed to examine the lysoPC composition of oxidized LDL samples from normal and hyperlipidemic subjects, and their effects on the impairment of endothelium-dependent relaxation. Oxidatively modified LDL from hyperlipidemic patients contained a slightly higher level (17%) of lysoPC, but produced a disproportionately greater impairment of endothelium-dependent relaxation than that from normal subjects. As lysoPC is composed of many molecular species, its composition in oxidized LDL samples was analyzed. In hyperlipidemic patients, lysoPC samples were found to contain a higher proportion of long-chain acyl groups. Subsequent studies revealed that only long-chain lysoPC (C > 16:0) were effective in impairing endothelium-dependent relaxation. Experimental loading of oxidized LDL from normal subjects with long chain lysoPC to mimic levels observed in oxidized LDL from hyperlipidemic patients resulted in further impairment of endothelium-dependent relaxation. We conclude that the greater proportion of long-chain lysoPC found in the oxidized LDL of hyperlipidemic subjects is responsible for the increased impairment of endothelium-dependent vascular relaxation. We propose that the high level of LDL found in the plasma of hyperlipidemic patients, coupled with its enhanced ability to generate long chain species of lysoPC during oxidative modification, are important factors for the development of atherosclerosis in these patients.

Adult↗
PubMed1997

Uses and limitations of routine hospital admission/separation records for perinatal surveillance.

This study examined the quality of data for delivering mothers and their newborns (April 1, 1984 to March 31, 1995) recorded by the Canadian Institute for Health Information (CIHI). The number of illogical and out-of-range values in the CIHI data were quite few; the occurrence of maternal and infant diseases estimated from CIHI data was quite similar to that in the literature; and major medical/obstetric complications recorded in CIHI were, in general, good predictors of adverse pregnancy outcomes. The authors conclude that CIHI data contain some of the information pertinent to perinatal surveillance that may be used to monitor maternal and infant health and to assess intrapartum care and hospital resource utilization. To adequately monitor and analyze patterns of health determinants and outcomes in all pregnant women and their infants in Canada, additional data collection mechanisms are needed to cover all recognized pregnancies and to collect antenatal and postpartum information and more detailed information on intrapartum care.

Adolescent↗
PubMed1997

Oxidative and malondialdehyde modification of low-density lipoprotein: a comparative study.

Low-density lipoprotein (LDL) was modified with copper ions (Cu2+) and malondialdehyde (MDA), and the differences were compared. The results show that both oxidative and MDA modification produce a decrease in free amino groups in LDL and enhance its electrophoretic mobility on agarose gel, and that these observations are linked. However, differences produced by the two forms of modification were observed. Oxidative modification of LDL involves free radical-mediated lipid peroxidation which produces large amounts of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes. In addition, vitamin E was reduced considerably and cholesterol lowered, and apolipoprotein B (apo B) fragmentation and aggregation were seen. Similar changes were not seen with MDA modification which does not involve lipid peroxidation. Fluorescence emission spectra of both forms of modified LDL show that emission intensity increases gradually as the modification progresses, but maximum emission wavelength and spectrum patterns are not the same. These findings may be of some significance in the study of the antigenicity, scavenger receptor multiplicity and toxic effects of modified LDL.

Copper↗
PubMed1997

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with the clinico-pathological manifestations in immunoglobulin A nephropathy patients.

OBJECTIVE: To investigate the relationship between angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism and the clinico-pathological manifestations in patients with immunoglobulin nephropathy (IgAN). METHODS: A flanking primer pair and an insertion-specific primer pair were used to perform two polymerase chain reactions so as to analyse the insertion/deletion polymorphism of ACE gene. RESULTS: There was a significantly higher genotype frequency for DD genotype in IgAN patients. The frequencies for DD genotype were also higher in those patients with hypertension and/or heavy proteinuria and/or severe glomerular sclerosis (P < 0.05). CONCLUSIONS: We observed a significant association of the deletion polymorphism of ACE gene with renal insufficiency, hypertension and severe glomerular lesions at biopsy. The deletion allele may play a role, at least to some extent, in the deterioration and progression in IgA nephropathy.

Adolescent↗
PubMed1997

Comparison of tyrosine hydroxylase immunoreactivity in cochleas of chinchilla and guinea pig.

OBJECTIVE: To investigate the distribution of the tyrosine hydroxylase (TH) immunoreactivity in the cochleas of chinchilla and compare it with guinea pig. METHODS: Ten healthy chinchillas and six healthy guinea pigs were used in this study. The surface preparation of cochleas were obtained by microdissection. The TH-like immunoreactivity on the surface preparation as examined by the avidin and biotinylated horseradish peroxidase macromolecular complex (ABC) technique and investigated with light microscopy. RESULTS: TH-like immunoreactivity was seen in the region from modiolus to the habenula perforata. There are two different groups of fibers in this area, one is blood vessel dependent, the other is a blood vessel independent system. No TH-like immunoreactivity was present in the inner spiral bundle (ISB) and the tunnel spiral bundle (TSB) regions in chinchilla cochleas. TH-like immunoreactivity was found in the region from modiolus to the habenula perforata and the ISB and TSB regions in the organ of corti (OC) in guinea pig cochleas. CONCLUSIONS: The presence of TH-immunoreactivity on the cochlea of chinchilla and guinea pig is different. TH-like immunoreactivity on chinchilla cochlea was involved only in the fibers corresponding to the sympathetic fibers on cochlea of guinea pig. No fibers corresponding to the dopaminergic olivocochlear lateral efferent system of guinea pig were found in ISB and TSB within the OC in chinchilla.

Adrenergic Fibers↗
PubMed1997

Immunoreactive growth hormone in human peripheral T lymphocytes: encoding sequence of cDNA identical to that of the pituitary human growth hormone.

OBJECTIVE: To detect the cDNA sequence of immunoreactive growth hormone (irGH) in human lymphocytes and to compare it with that of human growth hormone (hGH) in the pituitary. METHODS: The mRNA of irGH in human peripheral blood mononuclear cells (PBMC) was detected by Northern blot analysis. The cDNA of irGH was obtained by reverse-transcriptase and polymerase chain reaction amplification and obtained by screening from a cDNA library of human T lymphocytes. The sequence of irGH cDNA was determined and compared with that of the pituitary hGH. RESULTS: Very low level of irGH mRNA was detected in human PBMCs by Northern blot analysis. The cDNA sequence of the entire open reading frame of human irGH was 651 bp, which is identical to that of pituitary hGH. CONCLUSIONS: The same hGH molecule can be produced by human pituitary somatotrophic cells and human peripheral lymphocytes.

Amino Acid Sequence↗
PubMed1997

Establishment of doxorubicin-resistant human bladder cancer cell line (BUI-87/ADMR) and its mechanism of multidrug resistance.

OBJECTIVE: To establish a doxorubicin-resistant human bladder cancer cell line, BIU-87/ADMR, and to study its biological characteristics and mechanism of drug resistance. METHODS: A human bladder cancer cell line resistant to doxorubicin, BIU-87/ADMR, has been established in vitro by exposing BIU-87 parent cells to progressively increasing concentrations of the drug over a period of 8 months. The cell line has been characterized in terms of growth kinetics, morphology, cross-resistance to other anticancerous agents, pharmacokinetics of daunorubicin and expression of P-glycoprotein (P-gp) which is closely related to the MDR phenotype. RESULTS: The BIU-87/ADMR cell line was 6.3 times more resistant to doxorubicin than the parent BIU-87. It exhibited cross-resistance to doxorubicin derivatives (epirubicin, daunorubicin), vincristine and etoposide, but not to cisplatin and mitomycin C. Compared to the parent cells, the resistant cells have a slower growth rate and lower confluent density. Unlike the parent BIU-87, about 75% of the BIU-87/ADMR cells showed a positive reaction with monoclonal antibody against P-gp, JSB-1. Intracellular drug accumulation studies with fluorescence spectrometry indicated that the resistance exhibited by the BIU-87/ ADMR line was mainly caused by an increased active efflux. CONCLUSIONS: The results suggest that MDR is an important phenomenon in bladder cancer and that more than one pathway of MDR may be present in human bladder cancer cell lines. BIU-87/ADMR may be a useful model for the development of new chemotherapeutic strategies in overcoming drug-resistance in the treatment of bladder cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[Fetal hemodynamic surveillance of twin transfusion syndrome].

OBJECTIVE: To evaluate the ratio of peak systolic to least diastolic flow velocity (S/D), pulsatile index (PI) and resistance index (RI) of the umbilical arterial doppler flow at 20-40 gestational weeks in twin pregnancy for the surveillance of twin transfusion syndrome. METHODS: The fetal hemodynamics in 36 cases of twin pregnancy were monitored by Combison A-ZIPE 4871 with spectral doppler ultrasound. RESULTS: The value of S/D ratio and PI in 4 patients with twin transfusion syndrome at 32-34 weeks were significantly higher than those of normal twin (P < 0.01). Two cases of twin reversed arterial pressure (TRAP), i.e. artery to artery transfusion in one of the twin with acardius, were found at 26 and 26 + 4 weeks respectively. CONCLUSION: The S/D ratio and PI of umbilical artery might be useful indices for the surveillance of twin transfusion syndrome.

Adult↗
PubMed1997

[Blocking action of tetrandrine on the cell proliferation induced by PDGF in human lung fibroblasts and liver Ito cell of rats].

OBJECTIVE: To investigate the mechanism of hepatic fiberosis, the effects of platelet-derived growth factor (PDGF) on cell proliferation activity and collagen synthesis in human lung fibroblasts (HLF) and Ito cells of rat liver as well as the blocking action of tetrandrine on the cell proliferation induced by PDGF. METHODS: The Ito cells were separated from liver of rats by using the perfusion of collagenase and density pradient centrifugation. The cell proliferation was observed with the incorporation method of H-TdR and 3H-L-proline. RESULTS: Under condition of cell culture with 1% serum, PDGF could significantly enhance DNA synthesis, cell proliferation and collagen synthesis, which increased in degree with a rising of concentration of PDGF. This occurred in culture without serum, but under the same condition, if PDGF was applied together with insulin-like growth factor (IGF), it enhanced cell proliferation. The result also showed that the dose of tetrandrine below the level of inhibiting cell DNA synthesis could antagonize the stimulation action of PDGF on cell proliferation and collagen synthesis. CONCLUSION: Tetrandrine plays the blocking action in the promoting cell proliferation induced by PDGF.

Alkaloids↗
PubMed1997

[The treatment of nasopharyngeal carcinoma by using thermoradiotherapy].

The treatment effect of radiotherapy combined with local hyperthermia for nasopharyngeal carcinoma was studied in 23 patients. In 24 cases of the control group (radiotherapy), conventionally dynamic fractionation of dose was used. At 40 Gy, the regression of tumor was observed 83% in the study group and 54% in the controls group. No severe complications in patients treated by thermotherapy were noted. This paper discusses the role and the mechanism of local hyperthermia as a rediomodifying factor.

Adult↗
PubMed1997

[Experimental study on porous hydroxyapatite ceramics in repair of skull bone defect of rabbit].

In order to investigate the possibility of porous hydroxyapatite ceramics (HAC) in the repair of skull bone defect, twenty-four rabbits were used. The bone defect model was created by operation to obtain a defect in parietal bone in a size of 1 cm x 1 cm. Filled the defect with HAC and methyl-methacrylate-syrene copolymer (MMAS) to fill the defect as control. At 1st, 2nd and 3rd months after operation, behavior of the rabbits was observed and then these animals were sacrificed and specimens were examined under microscope. Results showed as follows: after operation, behavior of all animals were normal. By histological examination, it was found that in HAC group, there were granulation tissue, fibrous tissue and newly formed vessels grew into the pores and the osteoblasts formed osseous trabeculae. There was no inflammatory cell infiltration. In the MMAS grafted asea, there was formation of fibrous membrane. It suggested that HAC might be a good material for bone substitute in repair of skull bone defect.

Animals↗
PubMed1997

[The relationship between expression of basement membrane in squamous cell carcinoma of oral cavity and cervical lymph node metastasis].

Fifty seven cases of oral squamous cell carcinoma (SCC) were studied by immunohistochemical ABC method using type IV collagen and laminin antibody to investigate the relationship between expression and distribution of basement membrane in oral SCC and clinicopathologic characteristics and cervical lymph node metastasis. The distribution of basement membrane of oral SCC was discontinuous and in some cases the membranes disappeared. There was highly significant correlation between the staining patterns together with histologic differentiation degrees and cervical lymph node metastasis (P < 0.05). These indicate that the expression of baasement membrane in oral SCC may be a useful parameter for evaluation of tumor histologic differentiation and tumor invasion and metastasis.

Basement Membrane↗
PubMed1997

[Effects of lacidipine on serum oxygen free radicals and fasting levels of insulin in patients with essential hypertension].

Thirty patients with mild to moderate essential hypertension had received four weeks treatment with Lacidipine and serum lipid peroxide (LPO), superoxide dismutase (SOD) and insulin levels were measured before and after treatment. The results showed: (1) there were decreased in SOD activity and increased Lpo content the patients group (P < 0.01); (2) after treated with Lacidipine, the SOD acitvity increased and Lpo content decreased (P < 0.01); (3) Lacidipine had obvious antihypertensive effect with no significant changes in heart rate; (4) Lacidipine had no significant effects on insulin, blood glucose and lipids. The results suggest that lacidipine is a safe and effective antihypertensive agent and can improve the metabolic balances in free radical system.

Aged↗
PubMed1997

[Multiple factors analysis of formation of corneal haze after photorefractive keratectomy].

VISX 20/20 excimer laser was used to correct myopia from 1.00 to 16.00 diopters on 529 myopia eyes in 306 patients. All the patients were followed up for 3 to 12 months (8.1 +/- 3.1 months). At the 12th postoperative month, 0.5-3 grade corneal haze occurred in 62.1% of eyes in high myopia eyes, and only 8.8% in low and moderate myopia eyes (P < 0.01). The factors of formation of the corneal haze were the central corneal thickness, methods of removing epithelium and the number of laser pulses. The results suggest that the photorefractive keratectomy is regarded safe in correction of low and moderate myopia, but not in high myopia.

Adolescent↗