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Biomedical subjects

S Liu

Publications and source records attributed to S Liu.

At least 217 records · Page 12Linked to original sources
PubMed2001

[The study of human papillomavirus(HPV) DNA expression in middle-ear carcinomas].

OBJECTIVE: To study the expressions of human papillomavirus DNA in the middle-ear carcinomas. METHOD: A PCR method using consensus primers for the detection of HPV6,11,16,18 was applied in 5 biopsies of middle-ear carcinomas. Eight biopsies of mucosa in middle-ear and mastoid were concluded as controls. RESULT: It was found that a resulting 80% (4/5) of the middle-ear carcinomas contained high-risk-type HPV DNA, while the 0%(0/8) of the controls. CONCLUSION: The high prevalence of high-risk-type HPV in carcinomas of the middle ear suggests that viral infections may be an important etiologic component in the carcinogenic process.

Adult↗
PubMed2001

[Purification and properties of chitinase from Enterobacter aerogenes].

A bacterium producing chitinase was isolated from the dead body of Gymephorap ruoergensis. A chitinase was isolated from the culture of E. aerogenes and purified by means of ammonium sulfate precipitation, DEAE-cellulose column chromatography, and Sephadex G-100 column gel filtration. The purified chitinase showed homogeneity on the native polyacrylamide gel electrophoresis. Its molecular weight was estimated to be about 42.5 kD by SDS-PAGE. The optimum pH and temperature for hydrolysis of chitin were 6.0 and 55 degrees C respectively. Michaelis constant was 2.88 mg/mL. Different metal ions showed different effects on the chitinase activity, The chitinase activity was enhanced by Zn2+, Ba2+, Ca2+, Mn2+ and was strongly inhibited by Hg2+, Co2+, Mg2+.

Animals↗
PubMed2001

[Cloning and sequence analysis of the phytase phyA gene of Aspergillus niger N25].

The phyA encoding phytase of Aspergillus niger N25 was amplified by the polymerase chain reaction (PCR) with primers designed according to the sequences of the phyA in GenBank. The amplified fragment was cloned and sequenced. The results show that: the coding region is 1506 bp in size, includes a 102 bp intron, and encodes a peptide of 476 amino acid residues, in which there is a signal peptide with 19 amino acids and a mature peptide of 448 amino acids. Comparison of this sequence with the phyA of the natural A. niger NRRL3135 (GenBank Accession: M94550), the most highly secreting-phytase strain, shows that the nucleotide homology is as high as 96.746%, and the amino acid homology comes up to 97.64%. The phyA of A. niger N25 strain in this paper is appropriate to be used to construct the phytase gene-engineering bacteria.

6-Phytase↗
PubMed2001

[Immunohistochemistry research on keratoconus].

PURPOSE: Keratoconus is a noninflammatory disease characterized by thining and ectasia of the central cornea. The etiology and pathogenesis of keratoconus remain unclear. We studied the composition of basement membranes (BM) in normal, scarred and keratconus corneas to find out possible changes specific for keratoconus. METHODS: Paraffin-embeded sections of normal, scarred and keratoconus corneas were immunostained with antibodys against type IV collagen, Fibronectin (Fn) and Laminin (Ln). RESULTS: Keratoconus had increased staining of the epithelial BM for alpha 1-alpha 2 chain of type IV collagen and Fn, especially in scarred corneal regions. A similar enhancement was also observed in scarred corneas, and there was no significant difference between keratoconus and scarred cornea. CONCLUSION: A process similar to wound healing would largely contribute to the differences seen in the keratoconus.

Adolescent↗
PubMed2001

[Application of dot immunogold filtration assay in antibody detection for cysticercosis].

OBJECTIVE: To detect serum antibody of cysticercosis by dot immunogold filtration assay for establishing a diagnostic kit for cysticercosis patients. METHODS: Cyst fluid of cysticercus of Taenia solium after dialysis was used as diagnostic antigen in dot immunogold filtration assay and enzyme-linked immunosorbent assay to detect the serum antibody in patients with cysticercosis. Samples to be detected included 71 sera from patients with cysticercosis, 90 sera from healthy people, 20 sera from patients with other parasitic infections or brain tumor. RESULTS: The sensitivity and specificity of dot immunogold filtration assay were 90.1%(64/71) and 95.6%(86/90), respectively. No positive reaction was recorded in cases with other diseases except one serum from a patient with brain tumor. The coincidence rate between dot immunogold filtration assay and enzyme-linked immunosorbent assay was 94.4% (152/161). CONCLUSION: Dot immunogold filtration assay showed promising result for the diagnosis of cysticercosis.

Animals↗
PubMed2001

[The protein expression of p53 and bcl-2 in laryngeal squamous cell carcinoma].

OBJECTIVE: To detect the relationship of p53 and bcl-2 gene to laryngeal carcinoma. METHODS: p53 and bcl-2 protein expressions were examined in the specimens of 60 laryngeal carcinomas and 8 vocal cord polyps by immunohistochemistry method. RESULTS: Overexpressions of p53 and bcl-2 were found in the laryngeal carcinoma specimens; the positive rates of p53 and bcl-2 protein expression were 61.7%(37/60) and 43.3%(26/60), respectively. Negative results were observed in all the vocal cord polyp specimens. The positive rates of p53 and bcl-2 expression were related to the histological grade and cervical lymphatic metastasis of laryngeal carcinoma but not related to clinical stage and tumor types. CONCLUSION: The results of this study support the hypothesis that p53 and bcl-2 gene may be involved in the apoptosis of laryngeal carcinoma and they may play an important role in the pathogenesis of laryngeal cancer.

Adult↗
PubMed2001

[Adenovirus-mediated Rb gene transfect for head and neck cancer].

OBJECTIVE: To evaluate the efficacy of Rb gene therapy in head and neck carcinoma. METHODS: We investigated the adenovirus-mediated Rb (Ad-Rb) gene transfect into human oral squamous cell carcinoma cell line (012) in both in vitro and in vivo models. RESULTS: The cells growth curve for 012 tumor cells transfect with Ad-Rb became lower after two days transfection and declined slightly by six days. Tumor growth in nude mice was also significantly retarded following Ad-Rb injection when compared with controls. Ad-Rb expression was identified by Western blotting in those tumors injected with Ad-Rb. CONCLUSION: These results implicated that the recombinant Rb gene adenovirus vector could efficiently transfect and inhibit oral squmous cell carcinoma. It might be an important candidate for gene therapy in head and neck cancer.

Adenoviruses, Human↗
PubMed2001

[The relationship between cell proliferation and apoptosis of vestibular epithelium in the developing guinea pig].

OBJECTIVE: The cell proliferation and apoptosis of vestibular epithelium in normal developing guinea pig were observed to elucidate the relationship and effect between proliferation and apoptosis in developing vestibular epithelium. METHODS: Twenty Guinea pigs with different developing ages were used in our studies. Cell proliferation was detected by proliferation cell nuclear antigen (PCNA) immunocytochemistry while apoptosis was detected by TdT-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) method and transmission electro-microscopy. RESULTS: PCNA staining had been detected in supporting cells but not in hair cells, and the positive cells were gradually decreased with ageing. The differentiated hair cells and supporting cells underwent apoptosis in vestibular sensory epithelium, and TUNEL-positive cells were also markedly decreased with ageing. After birth, TUNEL-positive hair cells were located at the top of ampulla. CONCLUSION: During the development of guinea pig, cell proliferation as well as apoptosis events diminish contemporaneously. The balance between proliferation and apoptosis may regulate the normal number of cells, and is related to guarantee the normal structure and function of inner ear.

Animals↗
PubMed2001

[Observation of nasal mucosal cilia ultrastructure of Kartagener's syndrome].

OBJECTIVE: To report the ultrastructure of nasal mucosal cilia of Kartagener's syndrome and the operative results of 2 cases. METHODS: Both two cases were underwent endoscopic sinus surgery. Transmission and scanning electron microscopic examinations of nasal mucosa for case 1 were performed. RESULTS: All 2 cases presented situs inversus, chronic paranasal sinusitis and bronchiectasis. The electron microscopic examination showed that the shape of nasal cilia and "9 + 2" structure were normal, but the lack of inner dynein arm of cilia and confused arrangement of central pair of microtubules were confirmed. The recurrent of nasal polyps after 1-year follow-up was observed in case 1. CONCLUSIONS: The disturbance of mucociliary clearance due to congenital ciliary structure defect might be the cause of chronic sinusitis and polyps, which might be one of reasons for poor prognosis after operation and we should pay more close attention.

Adolescent↗
PubMed2001

[Combined interleukin-2 and herpes simplex virus thymidine kinase gene therapy for head and neck squamous cell carcinoma].

OBJECTIVE: To assess the efficacy of combined interleukin-2 (IL-2) and herpes simplex virus thymidine kinase (HSV-TK) gene therapy for murine head and neck squamous cell carcinoma (HNSCC). METHODS: Ad IL-2 or/and Ad HSV-TK were injected into the tumor tissues directly after the murine HNSCC model was established. DL312 or PBS was used as control and ganciclovir (GCV) was used at 25 mg/kg for 7 days in Ad HSV-TK gene treatment groups. Tumor size was measured before and after treatment to evaluate the response to treatment. Cytotoxic T-lymphocyte (CTL) and natural killer (NK) assays were performed and IL-2 expressions were also measured after IL-2 gene transfection. RESULTS: HNSCC tumor growth was significantly inhibited following combined IL-2 and HSV-TK gene therapy as compared to other groups (P < 0.05). Increased levels of IL-2 protein expression was found in combined and single IL-2 treated groups. The combination and IL-2 treated groups produced greater activities of CTL and NK than that of the controls. CONCLUSION: IL-2 gene therapy can efficiently induce antitumor immunity of the host and enhance antitumor effects of HSV-TK. Combined IL-2 and HSV-TK gene therapy could significantly inhibit HNSCC tumor growth in the murine model.

Animals↗
PubMed2001

[Detection of mutations in exon 7 of p53 from fresh tumor samples by single-strand conformation polymorphism and direct DNA sequencing].

OBJECTIVE: To detect mutations of exon 7 of p53 gene in laryngeal squamous cell carcinoma (LSCC) and analyze the relationship between the mutation and LSCC. METHODS: Fresh tumor samples from 60 LSCC patients were examined using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct DNA sequencing. RESULTS: An extra band in SSCP 3 was shown in 25 out of 60 samples. Exon 7 of p53 were detected by direct DNA sequencing in 8 samples taken at random from 25 cases. In 8 cases, 1 base pair deletion CCC-->CC in 250 codon which may result in frame shift mutation was shown. Simultaneously, in 3 cases, transversion AGT-->GGG in 261 codon which may bring out missense mutation was found. In 2 cases, 1 base pair deletion CGG-->GG in 248 codon was detected. In another case, 1 base pair deletion AGG-->AG in 249 codon was detected. Transversion ATC-->TTC in 254 codon was found in one of the cases. Transversion GGT-->TCA in 262 codon was found in another case. CONCLUSION: The codon 248, 250, 261 may be "hot spots" in LSCC. Mutations and deletions in exon 7 of p53 gene occurred frequently in LSCC.

Adult↗
PubMed2001

[Characteristics in frequency domain by inductively coupled plasma atomic emission spectrometry with charge injection detection].

The characteristics of two-dimension spectra obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) with charge injection detection (CID) in frequency domain were studied in the present paper. The measurement spectra were Fourier transformed and the frequency distribution of the spectra was obtained. Results showed that the spectra in frequency domain could be divided into two parts: high frequency and low frequency signals. The later stood for measurement spectra and the former for background and noises. However, the high frequency signals could not be smoothed simply to reduce noises because the background was deteriorated even though the spectral signal did not change significantly.

Mass Spectrometry↗
PubMed2001

[Green electroluminescence generated from a new rare earth complex: Tb(asprin)3phen].

Pure Green and narrow bandwidth emission from organic electroluminescent device was presented by using a new rare earth complex Tb(asprin)3phen as emissive layer. The structure of the device was ITO/PVK:Tb(asprin)3phen/Al, where PVK was used to improve the film-forming ability and conductivity of Tb(asprin)3phen. The electroluminescent property of the device was studied. It proved that this new kind of rare earth complex has excellent optoluminescent and electroluminescent properties. The electroluminescent mechanism of the device was proposed by measuring and analyzing the emission and excitation spectra of the emissive layer. The excitation spectrum of Tb(asprin)3phen-dispersed PVK film was very similar to that of the PVK. We proposed that the excited carriers of PVK and Tb(asprin)3phen were captured by Tb3+ and light was emitted when the electrons and holes recombined at Tb3+.

Chelating Agents↗
PubMed2001

[Simultaneous determination of three components in antongding injection by Kalman filtering method].

Kalman filtering method was applied to determine three components in antongding injection without separation. The average recovery and relative standard deviation of amidopyrine, phenazone, barbital obtained by Kalman filtering method were 99.8%, 0.93%, 99.7%, 0.82%, 99.7%, 1.5% respectively. It was showed by t-test that there was no significant difference between the results of Kalman filtering method and standard method.

Aminopyrine↗
PubMed2001

[Analysis of the parkin gene deletion mutations in Chinese patients with Parkinson's disease].

OBJECTIVE: Clarify parkin gene deletion mutations at exons 3 to 7 in Chinese patients with Parkinson's disease (PD) and analyze them together with the clinical features of PD. METHODS: DNA was extracted from peripheral blood of 33 sporadic PD patients and 6 familial PD patients. Deletion mutations of parkin gene were identified by PCR amplification and agarose gel electrophoresis. The clinical data were analyzed together with the above information. RESULTS: Of the 33 sporadic PD patients, 1 had exons 5 and 7 deletion, 2 had exon 7 deletion. The age of onset was 46, 48, 50 respectively. In the 6 familial PD patients, 1 had exon 5 deletion. The inheritance pattern in this patient was autosomal recessive and onset of the patient was 60. All of the patients who had parkin gene deletion mutations had tremor, rigidity and bradykinesia, but athetosis was not found. In addition, deletion mutations of parkin gene at exons 3, 4 and 6, were not found. CONCLUSION: There are deletion mutations of parkin gene at exons 5 and 7 in Chinese PD patients.

Adolescent↗
PubMed2000

Expression of cytochrome P450(11beta) (11beta-hydroxylase) gene during gonadal sex differentiation and spermatogenesis in rainbow trout, Oncorhynchus mykiss.

Androgens and especially 11-oxygenated androgens are known to be potent masculinizing steroids in fish. As a first step to study their physiological implication in gonadal sex differentiation in fish, we cloned a testicular cytochrome P450(11beta) (11beta-hydroxylase) cDNA in the rainbow trout, Oncorhynchus mykiss. We isolated a 1882 bp P450(11beta) cDNA (rt11betaH2, AF217273) which contains an open reading frame encoding a 552 putative amino acids protein. This sequence was highly homologous (98% in nucleotides and 96.5% in amino acids) to another rainbow trout P450(11beta) sequence (AF179894) and also to a Japanese eel P450(11beta) (68% in amino acids). Northern blot analysis detected a single transcript of 2 kb which was highly expressed in the testis (stage II) and to a lesser degree in the anterior kidney (containing the interrenal tissue). No signal was detected in the posterior kidney, brain, liver, skin, intestine and heart. In the testis this transcript was highly expressed at the beginning of spermatogenesis (stages I and II), followed by a decrease during late spermatogenesis (stages III to V). By semi-quantitative reverse transcription polymerase chain reaction, P450(11beta) expression during gonadal differentiation was estimated to be at least 100 times higher in male than in female gonads. This difference was first detected at 55 days post-fertilization (dpf), i.e. 3 weeks before the first sign of histological sex differentiation, and was sustained long after differentiation (127 dpf). Specific P450(11beta) gene expression was also demonstrated before testis differentiation (around 50 dpf) using virtual Northern blot, with no expression detected in female differentiating gonads. From these results, and also based on the already known actions of 11-oxygenated androgens in testicular differentiation in fish, it is now suggested that P450(11beta) gene expression is a key factor for the testicular differentiation in rainbow trout.

Amino Acid Sequence↗
PubMed2000

Roles of Se and NO in apoptosis of hepatoma cells.

Mice inoculated with hepatoma cell (H22) suspension subcutaneously at their right axilla were administered orally with kappa-selenocarrageenan (Se) solution, the inoculated hepatoma's growth was suppressed. Different concentrations of Se solution added in human hepatoma cell line culture could inhibit proliferation and induce apoptosis in hepatoma cells. Meanwhile Se solution could increase the activity of glutathione peroxidase (GSH-Px) in the mice's plasma and the content of NO in the mice's sera and the hepatoma cell culture supernatant as well. Therefore, apoptosis in hepatoma cell induced by Se solution may be associated with the increase in antioxidative activity, the suppression free radical's intervention, and the excessive release of NO by stress.

Animals↗