Biomedical subjects

J Xue

Publications and source records attributed to J Xue.

At least 73 records · Page 4Linked to original sources

PubMed1998

Murine enamelin: cDNA and derived protein sequences.

Enamelin is the largest enamel protein. Recently we reported the characterization of a cDNA clone encoding porcine enamelin. The secreted protein has 1104 amino acids--over 6 times the length of amelogenin (173 amino acids) and almost 3 times the lengths of sheathlin (395 amino acids) and tuftelin (389 amino acids). Immunohistochemistry has shown that uncleaved porcine enamelin concentrates at the growing tips of the enamel crystallites while its cleavage products localize to rod and interrod enamel. Here we report the isolation and characterization of cDNA encoding murine amelogenin and demonstrate the tooth specificity of porcine enamelin. The murine clone is 4154 nucleotides in length and encodes a protein of 1274 amino acids. In the absence of post-translational modifications murine enamelin has an isotope averaged molecular mass of 137 kDa and an isoelectric point of 9.4. Multiple tissue Northern blot analyses detect porcine enamelin mRNA in developing teeth but not in liver, heart, brain, spleen, skeletal muscle and lung. Mouse and porcine enamelin share 61% amino acid identity and 75% DNA sequence identity. Mouse enamelin has 14 tandemly arranged copies of an 11 amino acid segment that is found only once in porcine enamelin.

Amino Acid Sequence↗

PubMed1998

Enamelysin mRNA displays a developmentally defined pattern of expression and encodes a protein which degrades amelogenin.

Previously, a cDNA encoding a novel matrix metalloproteinase (enamelysin) was isolated from a porcine enamel organ-specific cDNA library. The cloned mRNA is tooth-specific and contains an open reading frame encoding a protein composed of 483 amino acids (Gene, 183:(1-2), p123-128, 1996). Here, we show that: 1) The expression of enamelysin mRNA is not limited to the enamel organ as previously reported. The enamelysin message is also expressed at very low levels in the pulp organ. 2) Northern analysis reveals that the enamelysin mRNA displays a developmentally defined pattern of expression in the enamel organ. The message is expressed at relatively high levels during the presecretory and early transition stages of development. However, during late maturation, the quantity of enamelysin mRNA is greatly reduced. Conversely, the low message levels in the pulp organ remain relatively constant throughout these developmental stages. 3) The enamelysin cDNA was ligated into a prokaryotic expression vector and recombinant enamelysin containing a His tag was purified from E. coli. Zymographic analysis utilizing recombinant murine amelogenin as the substrate, reveals that the purified enamelysin degrades amelogenin. Since enamelysin is developmentally regulated and is capable of degrading amelogenin, it is likely to play a significant role during enamel biomineralization.

Amelogenin↗

PubMed1998

Enamel matrix serine proteinase 1: stage-specific expression and molecular modeling.

Enamel proteins are cleaved by proteinases soon after their secretion by ameloblasts. Intact proteins concentrate in the outer enamel at or near the growing tips of the enamel crystallites while cleavage products accumulate in the deeper enamel. In the transition and early maturation stages there is a dramatic increase in proteolytic activity. This activity, coupled with the diminished secretory and increased reabsorptive functions of ameloblasts, leads to a precipitous fall in the amount of enamel protein in the matrix. Recently we have cloned and characterized an mRNA encoding a tooth-specific serine proteinase designated enamel matrix serine proteinase 1 (EMSP1) [Simmer et al., JDR (1998) 77: 377]. EMSP1 can be detected in the inner enamel during the secretory stage and its activity increases sharply during the transition stage. Stage-specific Northern blot analysis demonstrates this increase is accompanied by a parallel increase in the amount EMSP1 mRNA. A 3-dimensional computer model of EMSP1, based upon the crystal structure of bovine trypsin, has been generated and analyzed. All six disulfide bridges as well as the active site are conserved. Changes in the peptide binding region and the specificity pocket suggest that interaction of the proteinase with protein substrates is altered, potentially causing a shift in substrate specificity. The calcium binding region of trypsin is thoroughly modified suggesting that the calcium independence of EMSP1 activity is due to an inability to bind calcium. The three potential N-linked glycosylation sites, N104, N139 and N184, are in surface accessible positions away from the active site.

Amino Acid Sequence↗

PubMed1998

Suicide effect on rat gliomas mediated by recombinant adenovirus thymidine kinase/acyclovir system.

OBJECTIVE: To establish the replicated-deficient recombinant adenovirus-mediated thymidine kinase/acyclovir (Adtk/ACV) system and to evaluate its suicide effect on rat C6 brain gliomas in vitro and in vivo. METHODS: The plasmid pAdtk and pJM17 were co-infected into 293 cells (adenovector packaging cells) and the results were identified by polymerase chain reaction (PCR) assay. After the glioma C6 cells were transduced by Adtk at different multiplicity of infection (MOI) and exposed to different concentrations of ACV or gancyclovir (GCV), the cell survival curves were studied, and the cell surface was observed with scanning electronic microscopy (SEM). C6 gliomas in vivo at different inoculation days were injected with Adtk intratumorally and ACV intraperitoneally daily, and the survival duration and histologic changes of the rats were observed. RESULTS: The infectious Adtk virions had a suicide effect which was enhanced with the increase in MOIs of Adtk and ACV doses along with bystander effect. Under scanning electronic microscope, special pathologic changes were observed. ACV had a similar effect as GCV but a higher dose was used. The survival duration in day 3, day 6 and day 8 groups exceeded 90 days, and the rats in day 10 group survived 28.5 +/- 4.6 days, but the survival duration in untreated C6 group and AdLacZ/ACV (adenovirus-mediated LacZ/ACV) treated group were 16.8 +/- 3.1 and 14.0 +/- 2.2 days respectively. CONCLUSION: Adtk/ACV system can effectively kill the rat brain gliomas in vitro and in vivo.

Acyclovir↗

PubMed1998

Polymorphism of DXS102 locus in Chinese population and its application to gene diagnosis in hemophilia B family.

OBJECTIVE: To establish the polymorphism of DXS102 locus from Xq26.3-27.1 in Chinese population for the gene diagnosis in Hemophilia B family. METHODS: DNA was extracted from blood samples obtained from Shanghai unrelated volunteer donors with phenol-chloroform method. A total of 23x chromosomes (154 from females, 80 from males) were studied. A hemophilia B family in which a hemophilia B patient has received gene therapy was analyzed. The polymorphism of DXS102 locus in Chinese population was determined with amplified fragment length polymorphisms assay (Amp-FLP), denaturing polyacrylamide gel electrophoresis, silver stain detection. Short tandem repeats (STRs) linkage analysis was used to conduct gene diagnosis in hemophilia B family. RESULTS: Eight alleles were found at DXS102 locus, of which two alleles were first reported. The repeated number of AC dinucleotide ranges from 13 to 21. And the values of the observed heterozygosity, calculated heterozygosity and polymorphism information content(PIC) were 0.87, 0.80, 0.80 respectively. It was also found that the difference of the allele frequencies of DXS102 in Chinese and European populations was significant. By using the linkage analysis of the DXS102 locus, a family with a hemophilia B patient receiving gene therapy in 1994 was analyzed and meanwhile a carrier in that family was then detected. CONCLUSIONS: The polymorphism of DXS102 locus reveals significant difference between Chinese and European populations. DXS102 locus can be used as a promising marker for gene diagnosis in hemophilia B family.

Alleles↗

PubMed1998

[Effects of nitric oxide on the airway inflammation and lymphocyte proliferation in sensitized rats].

OBJECTIVE: To investigate the relations between intrinsic nitric oxide (NO) and airway inflammation and lymphocyte proliferation in bronchial asthma. METHOD: The rat model of asthmatic airway inflammation was established by first sensitizing and then challenging the animals with ovalbumin. NO synthase (NOS) inhibitor and NO precursor were then applied and their influences on the airway inflammatory cell numbers and on the numbers of mIL-2R positive lymphocytes were observed. RESULT: In vivo experiments showed that normal control rats (n = 6) did not have eosinophils in their submucosal of airways while in the sensitized animals (n = 6) eosinophils [23 +/- 5 (average cell counts per microscopic visual field, the same below) as well as lymphocytes (34 +/- 5) and mIL-2R positive cells (12 +/- 3) were found in significantly increased numbers in the airways. The application of NOS inhibitor significantly reduced eosinophils (13 + 3, P < 0.05) and mIL-2R positive cells (4.3 +/- 1.6, P < 0.05) in the sensitized animals and the number of lymphocytes was also decreased (28 +/- 4) although it did not reach the significant level. At the same time the spleen cell proliferation was inhibited (P < 0.05) and the mIL-2R positive spleen cell numbers were reduced (P < 0.05). On the contrary, the application of NO precursor resulted in the further increase of the numbers of eosinophils, lymphocytes and mIL-2R positive cells although the differences were not statistically significant. In vitro experiments showed that NOS inhibitor inhibited the proliferation of cultured spleen lymphocytes as well as their mIL-2R expression (P < 0.05). NO precursor, when used in low dose, could promote the proliferation and mIL-2R expression of spleen cells (P < 0.05); but high dose of it showed inhibiting effect on the spleen cells (P < 0.05). CONCLUSION: Intrinsic NO at a suitable level is important in the regulation of the proliferation and activation of lymphocytes in the airways with allergic inflammation in the sensitized rats. This research is conducive to the understanding of the pathogenesis of the asthmatic airway inflammation and to investigating of new therapeutic approaches.

Animals↗

PubMed1998

[Application of capillary electrophoresis on environmental analysis].

A review of applications of capillary electrophoresis (CE) on environmental analysis is presented, based mainly on the worldwide published works in the latest years. The current achievements and application potential of CE in the field of environmental analysis are included with 58 references.

Electrophoresis, Capillary↗

PubMed1998

[The influence of intrahepatic transplantation of hepatocytes and insular cells on liver cirrhosis].

OBJECTIVE: To protect liver function, we used the cirrhotic rats to study whether the postshunt intrahepatic transplantation of hepatocytes and insular cells via hepatic artery can improve liver function. METHOD: We irrigated the cirrhotic liver of rat via hepatic artery with hepatocytes and insular cells and observed the influence of this method on liver function. RESULT: The improvement of TP, ALB and TBIL in the experimental group were significant, and there was significant difference in these parameters between the experimental and control groups (P < 0.01). Light microscopic examination of liver fibrosis and immunohistochemistry and data analysis of I, II collagens also showed significant difference (P < 0.05). CONCLUSION: The intrahepatic transplantation of hepatocytes and insular cells via hepatic artery can not only improve liver function, but also increase the degradation of liver collagens and reverse the course of liver cirrhosis.

Animals↗

PubMed1998

[Clinical analysis of laser prostatectomy].

OBJECTIVE: To study the effect of laser prostatectomy for benign hypertrophy of prostate by transurethral noncontact laser ablation. METHOD: 204 patients with benign prostatic hyperplasia were treated by transurethral noncontact laser ablation. RESULT: 163 patients resumed urination in a week, and 37 in two weeks. Four patients were treated by open procedure. Patients were followed up for 14 months. Symptomatic scores (I-PSS) exceeded the middle rank in 90% patients and the maximum urinary flow rate was 89%. CONCLUSION: It is an effective method for adjusting the strength, direction, range and frequency of laser to prevent bleeding, perforation and long-term urethral stricture.

Aged↗

PubMed1998

[The influence of side-to-side portacaval shunt plus enhancement of perfusion of hepatic artery on cirrhotic liver: an experimental study].

OBJECTIVE: To for improving the perfusion of liver, we designed an operation of portacaval shunt (PCS) plus enhancement of perfusion of hepatic artery (EPHA). METHOD: 48 wistar rats were divided into 4 groups randomly. group I (normal control), group II (liver cirrhotic control), group III (PCS on liver cirrhosis), and group IV (PCS + EPHA on liver cirrhosis). The EPHA was performed by the ligation of the left gastric and splenic artery. Liver function tests, liver biopsy, and nuclide hepatobiliary dynamic imaging (NHDI) were performed on the 2nd week and the 6th month after operation. RESULT: In NHDI, the peak time was short (P < 0.05) and the excretive rate was high (P < 0.01). The liver function and the proliferative degree of the fibrotic tissue of the liver were perfected significantly (P < 0.05) in the group IV compared with the group III after operation. CONCLUSION: PCS + EPHA can increase the perfusion of the hepatic artery, maintain the liver function and delay liver cirrhosis, and overcome the side effects of PCS. It is a new surgical technique in treating portal hypertension.

Alanine Transaminase↗

PubMed1998

[Cloning and sequencing of fusion protein gene of recombinant GM-HBsAg].

GM-CSF is an effective adjuvant for immunology, it was used to improve the immunological function of antigen and to increase the anti-HBs responses. Through using polymerase chain reaction (PCR) technique, we amplified 384 bp and 846 bp gene fragments from GM-CSF and HBsAg. The products were extracted and purified; a 1230 bp gene fragment was obtained by T4 DNA linkage. This amplified product was cloned into pUC19 vector. The positive clones were screened and the inserted fragment was determined by restriction enzymes. The gene fragment length determined is 1230 bp, the sequence analysis showed that the gene fragment is GM-CSF-HBsAg gene. The successful construction of GM-HBsAg fusion protein gene provides basis for research of its biological activity and expression.

Base Sequence↗

PubMed1997

Association between lactation length and sow reproductive performance and longevity.

OBJECTIVE: To determine whether lactation length was associated with reproductive performance or longevity of sows. DESIGN: Cohort study. SAMPLE POPULATION: Data collected between 1986 and 1992 for sows in 15 breeding herds in Minnesota and Iowa. PROCEDURE: Sows were grouped into 4 genetic line categories according to their sources and 6 parity categories (1, 2, 3, 4, 5 or 6, and > or = 7). Multivariate regression analysis of reproductive performance was conducted, using the general linear model procedure Logistic regression was conducted with a dichotomous response variable for sow longevity (ie, removal from or retention in the herds). Odds ratios were obtained from estimated coefficients of the regression. RESULTS: Herd, genetic line, parity, year, month, and lactation length were significant in statistical models for litter (eg, number of live pigs/litter) and interval (eg, weaning-to-mating interval) traits. Interactions between lactation length and year, lactation length and genetic line, lactation length and parity, and lactation length and genetic line and parity were also significant. Sows removed from herds had a significantly shorter lactation length than did sows of the same parity that were retained in the herds. Sows that had shorter lactation lengths were at higher risk of being removed from the herds than were those that had longer lactation lengths. CLINICAL IMPLICATIONS: Lactation length is associated with reproductive performance and longevity, but genetic line and parity play a role as well. Thus, attention should be paid to genetic lines and parity of sows in the herd when implementing an early weaning production practice.

Animals↗

PubMed1997

Localization of the domains involved in ligand binding and activation of the glucose-dependent insulinotropic polypeptide receptor.

The receptors for the two structurally related insulinotropic hormones Glucose-dependent Insulinotropic Polypeptide (GIP) and Glucagon-Like Peptide-1 (GLP-1) share approximately 40% sequence identity and demonstrate complete specificity for their endogenous ligands, while utilizing similar second messenger pathways. In the current study chimeric GIP-GLP-1 receptors were prepared, and the effect of domain-exchange on ligand binding and adenylyl cyclase activation examined. A chimera (CH-2) consisting of the first 132 amino acids of the external N-terminal (NT) domain bound 125I-GIP with high affinity (27.77 +/- 11.85 nM). However, for receptor coupling to cAMP production it was necessary to extend the NT into the first transmembrane (TM-1) region (CH-3: IC50 = 9.04 +/- 1.07 nM; EC50 = 17.1 +/- 3.5 nM). A chimera which included part of TM-3 (CH-4) demonstrated binding and signalling (IC50 = 8.33 +/- 0.14 nM; EC50 = 467.5 +/- 173.6 pM) similar to the wild type receptor (IC50 = 1.33 +/- 0.19 nM; EC50 = 497.9 +/- 211.7 pM). Surprisingly constructs CH-2 and CH-3, while devoid of detectable 125I-GLP-1 binding, were capable of eliciting GLP-1-specific cAMP production (EC50s CH-2 = 81.4 +/- 19.6 nM; CH-3 = 5.99 +/- 0.68 nM) suggesting that receptor activation is not completely dependent on high affinity receptor binding. These data clearly demonstrate that the NT domain of the GIP receptor acts as the ligand-specific binding domain and that the first transmembrane domain is important for receptor activation.

Adenylyl Cyclases↗

PubMed1997

[Lasting expression of hF IX mediated by myoblasts in mice].

OBJECTIVE: To develop experimentally gene therapy for hemophilia B by using C2C12 cells and C3H mice as models. METHODS: The retroviral vector containing MCK enhancer and hCMV promoter was constructed and was used to transfect PA317 cells. Then the viral particles were used to transfect C2C12 cells and select the G418r clones,which were further confirmed by Southern, Northern, Western blots. And then the C2C12 cells expressing hF IX protein were injected into C3H mice and hF IX expression in vivo was studied. RESULTS: The expression level of hF IX in vivo was positively correlated with the number of injected cells, and the in vitro expression level of these cell clones. The expression of hF IX could be enhanced and prolonged by immunosuppressive agents. CONCLUSION: Allogeneic myoblasts transplantation leads to immunorejection, but repeated injections at a longer intervals could improve the existing rate of transplanted cells. And this might be helpful to gain insight into the myoblast-mediated gene therapy for hemophilia B patients.

Animals↗

PubMed1997

[DNA polymorphism analysis by capillary electrophoresis].

A review is given here to describe the principle and methods of gene polymorphism analysis by capillary electrophoresis (CE). DNA length polymorphism and sequence polymorphism are very important phenomena in gene molecular biology. Some practical works of gene length polymorphism analysis and sequence polymorphism analysis are listed. SSCP and HPA methods detecting gene point mutations are demonstrated. Applications of gene polymorphism analysis by CE in clinical, forensic and biological research are also discussed in this paper.

Animals↗

PubMed1997

Construction of mammary gland-specific expression vectors for human clotting factor IX and its secretory expression in goat milk.

Two expression vectors comprised of mouse matrix attachment regions (MARs), bovine beta-casein gene sequence, human factor IX (hFIX) minigene, and cDNA, pMCIXm and pMCIX, were constructed for the purpose of a mammary gland bioreactor. A secretory expression system of hFIX protein in milk was made using stearylamine (SA) liposome to transfect plasmid DNA directly into the mammary gland lobule of a lactating goat. The highest production of hFIX in goat milk was 13.7 ng/ml 3 days after transfection, and the hFIX production in the goat mammary gland transfected with pMCIXm containing hFIX minigene was obviously higher than that transfected with pMCIX containing hFIX cDNA. Activity immuno-analysis and the barium citrate absorption method showed that > 90% hFIX protein in milk appeared to be a gamma-glycosylated and biological activity. This result confirmed the validity of the constructed vectors for further transgenic study, and this assay could also find its success in the evaluation of a foreign gene expression and secretion in the milk as a rapid detection system using liposome to transfect DNA directly into the goat mammary gland.

Animals↗

PubMed1997

[Endometrial cytology in normal postmenopausal women and during hormone replacement therapy].

OBJECTIVE: To explore the possibility of endometrial cyopathologic examination as a method of monitoring endometrium during hormone replacement therapy (HRT) in postmenopausal women. METHODS: Endometrial cells were taken via tubal aspiration in 60 normal postmenopausal women (non-HRT group) and 41 with HRT for 3-18 months (HRT group). Their morphologic changes were observed and compared by cytopathologist. RESULTS: Atrophic endometrium was found in 51.7% of the non-HRT group. Its proportion increased with age and the time after menopause. Macrophages were seen in 68.3% of this group. However, in the HRT group the occurrence of atrophic type and macrophage (12.2%, 7.0% respectively) was significantly lower than that in the non HRT group (P < 0.05). Heterogeneity of endometrial cell type was shown both in non-HRT (38.3%) and HRT (65.8%) groups. CONCLUSIONS: Endometrial cells of postmenopausal women are not always atrophic in appearance. They change significantly during HRT. Endometrial cytological examination may be useful for monitoring during HRT.

Endometrium↗

PubMed1997

[The study of DSX-I type microcomputer autometic control injector system].

This paper studies the propulsive force of injector system controlled by 8031 single-chip microcomputer for Medical use By using one 8031 single-chip microcomputer as a microprocessor, the minimal autometic control system is constructed, which turns real-time control into reality. This product is a modern appliance used in diagnostic imaging medicine, in design of which the advanced instrument and electrical machinery are integrated into a unified structure. The clinic data demonstrate that the contrast medium can be injected to patients with rapidly and evenly. Dynamic CT Scanning can be intensified at any site of the body. x-ray dose exposed and lobour intensity to the operator can be decreased greatly, raise working efficiency.

Automation↗