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Biomedical subjects

G Zheng

Publications and source records attributed to G Zheng.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Study of relative factors which influenced the embolic level of microspheres in the hamster lingual carcinoma].

OBJECTIVE: To study the relative factors which influence the embolic level of microspheres in the hamster lingual carcinoma. METHODS: Micropicture analysis instrument was used to measure the embolic level of microspheres which were poured through ascending aorta. RESULTS: The optimum pressure of embolization was 30 kPa. The embolic level approached to remote site of the lingual artery as tongue cancer developed. In early invasive cancer period, the embolic level of microspheres was at arteriole level where microspheres block "the total values" which controlled the tumor microcirculation. The optimum embolic result and less offshoot microcirculation were obtained at this time. When in later period, microspheres mainly embolized the meta-arteriole. As the microvessels dilated, the dose of microspheres must be increased to get the best embolic result. CONCLUSION: The experimental data for clinical choice of optimum pouring pressure, optimum opportunity and optimum cases.

Albumins↗
PubMed1999

[Cloning and sequence characterization of heavy chain variable region gene from hybridoma cells secreting MAB against VEGF].

OBJECTIVE: To clone the variable region of heavy chain (VH) gene from hybridoma secreting monoclonal antibody against human vasoendothelial growth factor (VEGF) for construction of recombinant antibody (scFv). METHODS: One step method was used to extract total RNA and degeneration primer was used to amplify the cDNAs by retropolymerase chain reaction (RT-PCR), then the products were inserted to T-vector and its sequence was analysed. RESULTS: The VH gene contained 369 base pairs encoding 123 amine acid resides. Analysis of the nucleotide sequence of the light chain variable region revealed that the VH sequence was 87% identical to the sequence present in mouse Ig VH region. CONCLUSION: The VH gene was 369 bp. According to Kabat classification, the VH gene belonging to mouse kappa light chains subgroup I (A), resulting from VH-D-JH4 rearrangment.

Amino Acid Sequence↗
PubMed1999

[Design and synthesizing of human vascular endothelial growth factor (VEGF) peptide].

OBJECTIVE: To predict continuous epitopes of VEGF using synthetic peptide of VEGF as antigen to produce anti-VEGF-peptide monoclonal antibody. METHODS: According to amino sequence of VEGF189, antigen index program and Goldkey soft were used to predict VEGF epitopes, and the peptide containing one of predicted epitopes was synthesized by 430A Peptide Synthesizer. RESULTS: The NH2-terminal 1-26 amino acid sequence of VEGF was determined as synthetic peptide and synthesized. CONCLUSION: The predicted epitope of VEGF was synthesized, which provided an effective method when lacking of VEGF.

Amino Acid Sequence↗
PubMed1999

[Histopathologically observational study of cartilage-mucosa on the eustachian tube isthmus of temporal bone with otitis media].

OBJECTIVE: To explore the influence of inflammatory pathology change of otitis media upon cartilage-mucosa at the eustachian tube isthmus (ETI). METHOD: The cartilage-mucosa at ETI and bone-mucosa on the tympanic promontory of 32 temporal bones with otitis media were observated histopathologiclly in comparison with 50 normal temporal bones under light microscopy. RESULT: The eustachian tube isthmus in all the 32 temporal bone with otitis media and in 50 normal temporal bone were unblocked. The thick-measures and pathology observations of the cartilage-mucosa on ETI in the temporal bones with otitis media revealed there was no obviously inflammatory change and no significantly difference in comparison with the normal control group. But there was obviously inflammatory pathologic change on the bone-mucosa of tympanic promomtory of temporal bone with otitis media. The demarcation line of completely different inflammatory reaction in middle ear cleft was exactly at the connective line between cartilage and bone of eustachian tube. CONCLUSION: With the specifically histologic structure, the cartilage-mucosa on eustachian tube is possessed of very strong function of natural defence for inflammatory desease, and it almost is impossible to lead to obstruction of eustachian tube by inflammatory influence upon the cartilage-mucosa.

Cartilage↗
PubMed1999

[Study on the action force of dimerization of cobalt tetrasulfonate Ph-thalocyanine in aqueous solotion].

The dimerization of cobalt tetrasulfonate phthalocyanine (CoTSPc) was studied in the microemulsion, micelles and aqueous alcoholic solutions. The coordination reaction for the formation of complexes CoTSPc (L), which was formed by cobalt tetrasulfonate phthalocyanine (CoTSPc) plus ligand L(L = NH3, CN-, en), was also studied. The reaction kinetics was discussed and the stability constant K of CoTSPc(L)2 was also calculated from absorbance measurement.

English Abstract↗
PubMed1998

Epithelial cells up-regulate matrix metalloproteinases in cells within the same mammary carcinoma that have undergone an epithelial-mesenchymal transition.

A metastatic rat mammary carcinoma cell line, BC1, contains cells that have retained epithelial differentiation characteristics and metaplastic cells that have undergone an epithelial-mesenchymal transition. These two subpopulations cooperate to degrade collagen. We have used novel PCR assays to quantitate, for the first time, absolute levels of the mRNAs encoding matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in cell and tumor samples. BC1 tumors expressed high levels of the collagenase-3, TIMP-2, stromelysin-1, and gelatinase B genes and low levels of the stromelysin-2 and TIMP-1 genes. This pattern of expression was repeated in cultures of BC1 and cultures containing mixed clones of epithelial cells and metaplastic cells. In both BC1 and the biclonal cultures, metaplastic cells were the main source of collagenase-3, stromelysin-1 and stromelysin-2, whereas TIMPs were equally distributed and epithelial cells were the main source of gelatinase B. High levels of all four MMP mRNAs in metaplastic cells were dependent on coculture with epithelial cells, suggesting the production of an inducing factor by the epithelial cells. In contrast, gelatinase B mRNA was produced at a high level by epithelial cells in the absence of metaplastic cells. TIMP-2 mRNA was abundant in both subpopulations grown alone and did not change substantially upon coculture. Thus, the interclonal cooperativity to degrade collagen in BC1 cells required the induction of MMPs in metaplastic cells by epithelial cells. Interclonal cooperativity may be important to the progression of neoplastic tumors, a feature of which is phenotypic heterogeneity.

Animals↗
PubMed1998

Inhibition of cellular proliferation by the Wilms tumor suppressor WT1 requires association with the inducible chaperone Hsp70.

The Wilms tumor suppressor WT1 encodes a zinc finger transcription factor that is expressed in glomerular podocytes during a narrow window in kidney development. By immunoprecipitation and protein microsequencing analysis, we have identified a major cellular protein associated with endogenous WT1 to be the inducible chaperone Hsp70. WT1 and Hsp70 are physically associated in embryonic rat kidney cells, in primary Wilms tumor specimens and in cultured cells with inducible expression of WT1. Colocalization of WT1 and Hsp70 is evident within podocytes of the developing kidney, and Hsp70 is recruited to the characteristic subnuclear clusters that contain WT1. The amino-terminal transactivation domain of WT1 is required for binding to Hsp70, and expression of that domain itself is sufficient to induce expression of Hsp70 through the heat shock element (HSE). Substitution of a heterologous Hsp70-binding domain derived from human DNAJ is sufficient to restore the functional properties of a WT1 protein with an amino-terminal deletion, an effect that is abrogated by a point mutation in DNAJ that reduces binding to Hsp70. These observations indicate that Hsp70 is an important cofactor for the function of WT1, and suggest a potential role for this chaperone during kidney differentiation.

Amino Acid Sequence↗
PubMed1998

Immortalized rat proximal tubule cells produce membrane bound and soluble megalin.

Megalin (gp330), a glycoprotein receptor found on renal proximal tubule cells and several other epithelial cells, is deduced to be a type I integral membrane protein, but may also exist as a cell surface form lacking a cytoplasmic domain. Furthermore, soluble megalin products have been detected in urine, and in culture medium of a rat yolk sac carcinoma cell line, combined with receptor associated protein (RAP). Permanent renal cell lines expressing megalin were unavailable until the recent description of two immortalized rat proximal tubule cell lines (IRPTC). The present study demonstrated megalin on IRPTC surface by immunofluorescence, without surface staining for RAP, which was, however, readily detected within cells. Antibodies to ectodomain megalin epitopes immunoprecipitated megalin products both from cell lysates and culture medium, whereas antibodies to cytoplasmic domain epitopes precipitated megalin only from lysates. Western blots showed two major megalin products in medium, a prominent band at approximately 200 kDa, and a fainter band above 400 kDa, slightly below intact megalin in cell lysates. Anti-receptor associated protein antibodies immunoprecipitated megalin from IRPTC lysates, but not from media. We propose that portions of megalin are spontaneously produced by IRPTC, probably either by cleavage in the ectodomain or release of forms lacking a cytoplasmic domain.

Animals↗
PubMed1998

Megalin (gp330): a putative endocytic receptor for thyroglobulin (Tg).

Megalin (gp330) is a large glycoprotein receptor found mainly on a group of absorptive epithelial cells, including renal proximal tubule, epididymal and thyroid cells. Megalin has been shown to bind multiple, unrelated ligands, mainly in vitro, and to mediate endocytosis of ligandsin cultured cells. However, physiologic ligands of megalin are largely unknown. In the present study we have demonstrated that purified rat megalin binds rat thyroglobulin (Tg) in solid phase assays, with anestimated Kd of 9.2+/-0.6 nM. Binding was calcium dependent and was almost completely inhibited by excess Tg, by three megalin ligands - lactoferrin, lipoprotein lipase and apolipoprotein J- and by the receptor associated protein (RAP), which inhibits binding of all megalin ligands. Three anti-megalin antibodies partially inhibited Tg binding to megalin. 125I labeled Tg bound to megalin was released by EDTA and heparin; the released product was shown by SDS-PAGE and autoradiography to be 660 kD (dimeric) Tg. However, an immunoblotting experiment showed binding of megalin both to monomeric (330 kD) and dimeric Tg. We propose that megalin, which is known to mediate ligand endocytosis and is found on the apical surface of thyrocytes, may participate in the endocytosis of Tg from the colloid, a process that is required for hormone release from Tg.

Animals↗
PubMed1998

Study on the metastatic mechanisms of human giant-cell lung carcinoma comparison between the strains C and D.

The biologic characteristics of the two human giant-cell lung carcinoma strains with high (strain D) and low metastatic potential (strain C) were studied, including karyotype of chromosome, intracellular free calcium ([Ca2+]i), morphologic changes of cell surface and the expression of nm23-H1, p53, ras, c-myc, c-erbB2, bcl-2 genes and PCNA. The correlation between different biologic features and the metastatic potential of the two strains was analyzed. We found: 1) Both strains had the karyotypic abnormality of -13, -14, -15, +20, +21 with seven same marker chromosomes. Only strain D had the karyotypic abnormality of +7, -17, -18, +X, 7p+; 2) [Ca2+]i of the strain C (984.7 +/- 573.8) and D (517.6 +/- 216.6) was significantly different (p < 0.05). The amplitude of intracellular calcium oscillations of strain C was lower than the one of strain D; 3) strain C had more villous-like protrusions on the cell surface, whereas strain D had more bubble-like protrusions; 4) The expression of nm23-H1 and p53 protein of strain C was all higher than that of strain D. The expression of PCNA of strain C was lower than strain D; 5) nm23-H1 mRNA levels of strain C was lower than that of strain D. We consider that the karyotype of chromosomes, intracellular free calcium, the structure of cell membrane and the expression of nm23-H1 gene, p53 gene, PCNA could be closely related to the metastatic potential of human giant-cell lung carcinoma. They could be used as the sign for judging whether the tumor will metastasize in clinical practice as well as in judging the prognoses of patients.

Calcium↗
PubMed1998

A study of retentive filler and its use in dentistry.

OBJECTIVE: The purpose of this study was to develop a fine compound inorganic filler with special surface microstructure (called retentive filler or RF) and to investigate its use in composite resin and synthetic resin teeth. METHODS: Barium silicate glass and fine silicon dioxide or barium silicate glass were mixed and sintered, then dispersed and classified by sedimentation. The surface microstructure and the particle size distribution of retentive filler were surveyed, and the mechanical properties of the composite resin and the resin tooth material reinforced with RF were tested. RESULTS: Scanning electron microscopy showed that the surface of RF particles is distinguished for its retentive contour microstructure. The particle size of RF is smaller than 3 microns. The mechanical properties of composite resin reinforced with RF are better than that of composites containing normal fillers, and the wear resistance of the resin tooth material containing RF is better than that of normal synthetic resin. CONCLUSIONS: The RF can be successfully prepared by the technological process in this study. Because of the special surface microstructure, RF has a good bonding to the resin matrix. The testing results suggest that it is feasible to improve the mechanical properties, especially the wear resistance of the composite resin and resin teeth, by using retentive filler.

Barium Compounds↗
PubMed1998

[Determination of taurine in foods by high performance liquid chromatography].

Taurine (2-aminoethanesulfonic acid) was quantitated by reversed-phase liquid chromatography on a C18 resolve column (ZOBAX ODS) using a mobile phase of methyl alcohol-phosphate buffer (pH = 4.9). L-glutamine was used as the internal standard. Before separation, the sample was extracted with 0.2 mol/L sulfosalicylic acid solution and cleaned up with dual ion exchange column chromatography. The amino acid was derived with o-phthalaldehyde to form an amino acid adduct which was monitored at 340 nm by UV detector. The HPLC method for taurine analysis in foods showed the precision (relative standard deviation) is better than 5%. The recoveries are more than 95% and the detection limit is 12 ng of taurine.

Animals↗
PubMed1998

[Molecular biological evidence for the genetic stability of in vivo passaged doxorubicin resistant cell line S-180R].

OBJECTIVE: To assess the genetic stability of doxorubicin resistant sarcoma 180 cell line(S-180R) after in vivo passages. METHODS: Flow cytometry, Southern blot, Northern blot and RT-PCR were used to examine genes and molecules related to drug resistance. RESULTS: The drug-efflux of S-180R was nearly 100-fold as high as that of the parental cells. The ratio of half peak width to peak height was 0.23 as compared to 0.56 measured two years before when the S-180R cell line was initially established. The mdr-1 gene was significantly amplified and transcribed while the transcription of topoisomerase II alpha gene was decreased. However there was no increase in mRNA expression of the multidrug resistance associated protein(MRP). CONCLUSION: Compared with the initially established S-180R, its resistance to doxorubicin is not only maintained but in fact has been increased since in vivo passage for 2 years. The major mechanism is amplification and over-expression of mdr-1 gene, but decreased topoisomerase II alpha also contributes. S-180R is an ideal experimental model for the study of doxorubicin resistance and its reversion.

ATP-Binding Cassette Transporters↗
PubMed1998

[Analysis of the relations between Toynbee phenomenon and middle ear pressure].

This paper studied the relations between the middle ear pressure, the opening duration of eustachian tube (ET), and the duration of nasopharyngeal pressure phase during Toynbee maneuver by sonotubometry, tympanometry and nasopharynx manometry. The mucociliary clearance of ET in Toynbee maneuver was also studied by Saccharin method. The results showed that negative middle ear pressure induced by Toynbee maneuver was related to prolonged opening duration of ET and duration of negative pressure in nasopharynx and lower opening pressure of ET. This phenomenon was often shown on the patients with nasal obstruction, and reduced ET mucociliary clearance. The Toynbee phenomenon indicates a closing failure of the ET, clinically, this situation needs to be prevented and resolved in a timely manner.

Adolescent↗
PubMed1998

[Compositional analysis of two metal crowns and its cements unearthed from a Ming Dynasty grave in China by SEM].

OBJECTIVE: To investigate the prosthodontic level of our country in Ming Dynasty (from A. D. 1368 to A. D. 1644) and provide our courtry's history of stomatological development with some details. METHODS: By means of range estimation and SEM, the structure and shape of the metal crowns on the two human teeth which were unearthed from a Ming Dynasty grave, numbered 0754/0046 and stored in Wujin museum of Jiangsu province, as well as the compositions of the crowns and its cements were examined and analysed preliminarily. RESULTS: The two teeth looked like upper anterior teeth and no marks of preparations were observed. The golden-yellow metal crowns might have been hammered and welded into shape. The spectrum analysis of SEM showed the crowns were made from gold-copper alloy and the cements contains Zinc. CONCLUSION: The defects of teeth could have been restored with extra-hard gold-copper alloy and cement luting materials during A. D. 1500-1600 in China.

China↗
PubMed1998

[The choice of methods of intraocular lens implantation in traumatic cataract in the absence of capsular and zonular support].

OBJECTIVE: To study the choice between the methods of anterior chamber intraocular lens (AC-IOL) implantation and posterior chamber IOL suture fixation in traumatic cataract without posterior capsular support. METHODS: The study included 86 cases (86 eyes) with traumatic cataract. A new flexible open-loop one piece PMMA IOL was implanted in the AC-IOL group of 56 cases (56 eyes); fixation of a C-loop one piece PMMA IOL at ciliary sulcus with two sutures was performed on 30 cases (30 eyes) in the posterior chamber IOL (PC-IOL) group. RESULTS: The follow-up period was 1 - 42 months. The visual acuity 0.5 or better was in 71.4% (40/56) in AC-IOL group, in 90.0% (27/30) in PC-IOL group; 1.0 or better was in 39.3% (22/56) in AC-IOL group, in 46.7% (14/30) in PC-IOL group. CONCLUSION: Both AC-IOL implantation and PC-IOL suture fixation are the remedy methods when the PC-IOL intracapsular implantation is unsuccessful. The AC-IOL is suitable for old persons with good anterior segment (cornea, iris and the angle of anterior chamber) and poor posterior segment (vitreous, retina) situations, while the PC-IOL suture fixation is suitable for the young with relatively poor anterior segment and good posterior segment conditions.

Adolescent↗
PubMed1998

[Retinal detachment after intraocular lens implantation].

OBJECTIVE: To study the specificity of retinal detachment after intraocular lens implantation. METHODS: The specialty of this type of retinal detachment through the clinical observation of 44 eyes of 42 cases from 1991 to 1996 was analyzed. RESULTS: The retinal detachment after intraocular lens implantation is more severe than others. It is more difficult to find a hole or holes because posterior capsular opacification and the implanted intraocular lens interfere with the careful search. The retinal detachment may develop into a complicated one. Its cure rate was 80.0% in the immediate postoperative period. CONCLUSION: The retinal injury during intraocular lens implantation should be avoided. As the retinal detachment occurs after the implantation, a more careful search and a earlier scleral buckling or/and vitrectomy should be done.

Adult↗