Biomedical subjects

J Xu

Publications and source records attributed to J Xu.

At least 631 records · Page 35Linked to original sources

PubMed1999

[Cloning and sequencing of the genes coding for the histidine-rich protein II of Plasmodium falciparum].

AIM: To compare and analyze the homology of genes encoding histidine-rich proteinII (HRPII) of different Plasmodium falciparum isolates. METHODS: Using PCR technique, the complete genes coding for HRPII of P. falciparum isolates FCC1/HN and VN isolates were amplified. PCR products were digested by HindIII/BamHI and cloned into plasmid pUC19. The recombinant plasmid HRPII/pUC19 was screened and identified by PCR and restriction analysis. The cloned HRPII genes were sequenced by Sanger's method. RESULTS: HRPII genes of FCC1/HN and VN isolates were successfully amplified and cloned into pUC19. DNA sequencing showed that the coding length of HRPII gene was 1,020 bp without introns in FCC1/HN and VN isolates, however, there were ten points mutations between them. FCC1/HN isolate exhibited 98.8%, 92.2% and 98.7% homology in amino acids with isolates VN, IMTM22, and Itg2, respectively. Though the numbers of repeat sequences were different in four isolates, they had the same hydrophobic leader sequence and a single putative glycosylation site. The secondary structure analysis showed that the main antigenic determinants of four isolates were located on 5' end non-repeat region (amino acids 1-60). CONCLUSION: FCC1/HN isolate was highly homologous in the coding region of HRPII with VN, IMTM22, and Itg2 isolate. Four isolates exhibited similar structural characteristics and antigenic determinants in HRPII.

Amino Acid Sequence↗

PubMed1999

[Glottal configuration and histological findings in vocal muscles following trauma to cricoarytenoid joint].

OBJECTIVE: The unilateral cricoarytenoid joints of the rabbits were traumatized bluntly to investigate the changes of glottal configuration and histology of the vocal muscles. METHOD: 10 New Zealand white rabbits divided into 4 groups were studied. Under direct laryngoscope, the unilateral cricoarytenoid joint of each rabbit was traumatized bluntly. The glottal configuration and histology of the true cords demonstrated atrophy of the vocal muscles. The remarkable atrophy of the vocal muscles was evaluated after 1, 3, 6 and 9 months. RESULT: In 1 and 3 months after trauma, the glottal configuration of the rabbits showed no difference from that in the period of trauma. The histology of the vocal muscles was approximately normal. The lateral drift and deformity of the fixed vocal cord and wider glottal gap were seen 6 months after trauma. The histological sections of the vocal muscles were noted 9 months after trauma. CONCLUSION: The atrophy of the vocal muscles may occur 6 months after trauma to cricoarytenoid jonint. This pathologic change may cause the lateral displacement and deformity of the vocal cord, which increases the glottal incompetence and affects voice recovery. The laryngeal electromyography may be influenced by the pathologic changes of the vocal muscles.

Animals↗

PubMed1999

[Cloning and expressing of human papillomavirus 16 E7C subgene].

OBJECTIVE: To develop vaccine against HPV16 is the hotspot in this field, this study was to pave the rudiment for this purpose. METHODS: E7C subgene (encoding aa39 to aa98) was amplified by PCR, and then cloned into pLNCX plasmid. RESULTS: The recombinant pLNCE7C was obtained and identified by gel analysis of the restricted-endonuclease-digested fragments. It was shown that pLNCE7C was expressed in transfected B16 cells. The expression product was identified in the positive cells by Southern blotting and immunohistochemistry method. It was localized mainly in cytoplasm of B16 cells. CONCLUSIONS: The plasmid pLNCE7C containing subgene of HPV16E7C not only remains the antigenesis of E7 gene but also eliminates the transforming activity of it. Meanwhile the expression of pLNCE7C is quite good. Therefore the plasmid pLNCE7C is suitable to develop DNA vaccine against HPV16.

Animals↗

PubMed1999

[Study on GMA-DNA adducts in vivo].

OBJECTIVE: To investigate whether glycidly mechacrylate (GMA-DNA) adducts can be produced in various organs of rat in vivo. METHODS: Rats divided into 5 groups were orally administrated with mutagen, GMA 31.25, 62.5, 125, 250 mg/kg respectively for 14 days. DNA adducts produced in liver, kidney, white blood cells and testis had been analyzed by nuclease P1 mediated 32P-postlabelling method. RESULTS: Several GMA-DNA adducts were formed in various organs (in white blood cells, 4 types, liver and kidney, 3 types and testis 1 type). The amount of GMA-DNA adducts increased with GMA dosage within 0-125 mg/kg dosages, degree of the overall level of GMA-DNA adducts in various organs were kidney > liver > white blood cells > testis. N3-methacrylate-2-hdroxypropyl-deoxycytidine monophosphate was found in kidney, liver and white blood cells. CONCLUSIONS: GMA with electrophilic group could react with negatively charged centers on DNA and form GMA-DNA adducts.

Animals↗

PubMed1999

[Isolating, cloning, and sequencing of HPV16E6E7 gene from a cervical carcinoma biopsy in Shandong Province].

OBJECTIVE: In order to study the structure specificity of HPV16E6E7 gene of a Chinese patient of cervical carcinoma in Shandong province. METHODS: The tissue DNA were abstracted from cervical carcinoma biopsies and the type of HPV was identified by HPV multiple primers PCR. HPV16E6E7 gene was amplified by PCR from the cervical carcinoma tissue DNA with the infection of HPV16 type only, and then cloned the E6E7 gene into pALTERI vector. After sequencing the double strand, the gene was compared with the prototype E6E7 gene of HPV16. RESULTS: A new recombinant plasmid was constructed and named HPV16E6E7-SD. Sequencing results showed one mutation in HPV16E6E7-SD, the 557th neocleotide in the viral neocleotide sequence "T" was changed into "C", and caused the termination cordon TAA of E6 gene to convert into a Gln cordon CAA. CONCLUSIONS: There is a structure difference between HPV16E6E7-SD and the standard strain.

Base Sequence↗

PubMed1999

[Synthesis and distribution of type IV collagen in mice testes].

OBJECTIVE: The variations of the synthesis and distribution type IV collagen in the testes of young, adult, and old mice were studied. METHODS: Biotin-avidin DCS system indirect immunofluorescence technique and in situ hybridization method were used. RESULTS: Sertoli cell could synthesize type IV collagen. Type IV collagen was present in the basement membrane of seminiferous tubules in mouse testis. Type IV collagen mRNA signal was seen in the Sertoli cells. The content of type IV collagen and type IV collagen mRNA peaked at day 15, and then declined successively to adult value and the aged value. CONCLUSIONS: The results suggest that the extracellular matrix of testis might play an important role in the process of spermatogenesis.

Age Factors↗

PubMed1999

[Grey relational analysis on early bolting of Angelica and its main factors].

Selecting the principal environmental and cultivated factors from the main production areas of Angelica sinensis in Gansu, the problem of early bolting were analysed with grey system theory. After the quantitative analysis, the relational grade was: elevation > precipitaton > density of crop > organic fertilizer > phosphorus fertilizer > nitrogen fertilizer. The research would provide scientific basis for check on the rate of the early bolting of Angelica effectively as well as improve the product and benefits.

Altitude↗

PubMed1999

[Resources and utilization of anticarciogenic medical fungi].

This paper summarizes the resources of anticarcinogenic medical fungi, and the information of distribution, eco-environment. It outlines the present statuts of the exploitation and utilization of some species of common anticarcinogenic medical fungi such as Ganoderma lucidum, Coriolus versicolor, Polyporus frondosus etc. The anticarcinogenic mechanism of medical fungi is discussed. Suggestions on how to development and utilize rationally these resources are offered as well.

Animals↗

PubMed1999

[Dynamic observation of serological and histological changes of Chinese rhesus monkeys infected by hepatitis G virus].

OBJECTIVE: To study the genesis, development and pathogenesis of hepatitis G. METHODS: The Chinese Rhesus monkeys were intravenously injected with the serum from a hepatitis G patient only with HGV RNA positive. The dynamic changes of serum and liver tissues of the animals were observed before and after infection. Also the immunohistochemical study were done with monocolonal antibody against NS5 gene antigen of HGV. One male monkey was dissected and the internal organs were taken for histological examination 18 months after infection. RESULTS: Serum ALT and AST became increasing 30 days after infection and showed abnormal continuously for 9 months. Spotty and focal necrosis and piecemeal necrosis were found in liver tissue from 2 to 18 months after infection. Positive staining of HGV antigen was present in cytoplasm of liver cells by immunohistochemistry. Histological observation showed that the internal organs were normal except the liver tissue in which the damages were similar with that in hepatitis. CONCLUSION: The successful infection of Chinese Rhesus monkey by serum from hepatitis G patient can used as a good animal model for the study of hepatitis G.

Animals↗

PubMed1999

[A new absorbance ratio-derivative method and its application to simultaneous determination of two components in a mixture].

In this paper, the principle of a new absorbance ratio-derivative method was described. The experimental methods of derivation with subtraction technique on ordinary spectrophotometer and simultaneous determination of phenol and resorcin were studied. The result is satisfying. The recovery of resorcin and phenol is in the range of 99.4%-104.2% (n = 25, RSD = 1.1%) and 97.1%-102.8% (n = 25, RSD = 1.6%) respectively.

English Abstract↗

PubMed1999

[Time-resolved fluorescence investigations of aggregation in Langmuir-Blodgett multilayers of hemicyanine dye].

UV-visible absorption and steady-state and time-resolved fluorescence techniques were used to investigate the aggregation behavior in Y-type hemicyanine Langmuir-Blodgett (LB) multilayers. Hemicyanine molecules formed H aggregates in LB films leading to blue-shifts of the absorption and fluorescence bands with respect to those of monomeric hemicyanine in chloroform solutions. The aggregates in LB films were dissociated by mixing with arachidic acid. The measurement of fluorescence decay profiles could be used to quantitatively characterize the lifetime, weights and size of aggregates.

English Abstract↗

PubMed1998

Differential control of the phosphorylation state of proline-juxtaposed serine residues Ser725 of Stat5a and Ser730 of Stat5b in prolactin-sensitive cells.

Transcription factors of the Stat family are controlled by protein kinases. Phosphorylation of a positionally conserved tyrosine residue is obligatory for Stat dimerization, nuclear translocation, and specific DNA binding. Studies of Stat1 and Stat3 have suggested that serine phosphorylation may also regulate function. We now identify serine residues located in a conserved PSP motif of Stat5a (Ser725) and Stat5b (Ser730) as major phosphorylation sites, using mutagenesis, phosphoamino acid analysis, and site-specific anti-Stat5-phosphoserine antibodies. Unexpectedly, phosphorylation control of this PSP motif differed between the highly homologous Stat5a and Stat5b proteins. Whereas Ser725 of Stat5a was constitutively phosphorylated both in COS-7 cells and Nb2 lymphocytes, phosphorylation of Ser730 of Stat5b was markedly stimulated by prolactin. The data also suggested the existence of a second major serine phosphorylation site in Stat5a. Interestingly, constitutive phosphorylation of the PSP motif was suppressed by PD98059 but not by staurosporine under conditions in which both agents inhibited mitogen-activated protein kinases. Furthermore, pretreatment of cells with staurosporine, PD98059, H7, or wortmannin did not prevent either Stat5a or Stat5b from becoming maximally serine-phosphorylated after prolactin exposure. We propose that two pathways regulate Stat5 serine phosphorylation, one that is prolactin-activated and PD98059-resistant and one that is constitutively active and PD98059-sensitive and preferentially targets Stat5a. Finally, phosphorylation of the PSP motif of Stat5a or Stat5b was not essential for DNA binding or transcriptional activation of a beta-casein reporter gene in COS-7 cells, suggesting that serine kinase control of Stat5 activity differs from that of Stat1 and Stat3.

Alanine↗

PubMed1998

PhLPs and PhLOPs in the phosducin family of G beta gamma binding proteins.

In this study, we identify new isoforms of the retinal phosducin and investigate the expression of the phosducin family, showing that an isoform, PhLP1, has sequence homology with Phd and Gbeta gamma binding capability, whereas two isoforms (phosducin-like orphan proteins, PhLOPs) share sequence homology with Phd but fail to bind Gbeta gamma. Original identification of PhLP1 and the PhLOPs was from a human retina cDNA library, using a PCR product for library hybridization screening that contained a predicted functional epitope domain. The screen identified Phd and three related, but distinct, recombinants (PhLP1, PhLOP1, and PhLOP2). By RT-PCR, all isoforms are expressed in either retina or forskolin-stimulated Y79 retinoblastoma cells; however, the new isoforms are below the level of detection on Northern blot analysis. The predicted amino acid translation of each homologue revealed major differences, arising from either splice variants or gene duplication of Phd. To test the functional interaction of all phosducin isoforms with Gbeta gamma in vitro, a glutathione S-transferase (GST) fusion protein was developed for each member. Biochemical interaction with purified retinal transducin Gbeta gamma was verified for GST-Phd and demonstrated for GST-PhLP1; however, neither GST-PhLOP1 nor GST-PhLOP2 bound Gbeta gamma. Comparable results were observed when the GST-phosducin fusion proteins selectively sequestered Gbeta gammas from retinal extracts or when functional Gbeta gamma interactions were assessed using surface plasmon resonance technology. Phosducin and its isoforms are widely distributed in body tissues where they may participate in signal transduction pathways. Phd and PhLP1 possess an 11-amino acid conserved epitope domain (TGPKGVINDWR) that controls the high-affinity binding of Gbeta gamma; these isoforms are implicated in the G-protein signaling pathway. The phosducin-like orphan proteins (PhLOPs) fail to bind Gbeta gamma, suggesting that the PhLOP isoforms may participate in still unidentified signaling pathways.

Amino Acid Sequence↗

PubMed1998

The Epstein-Barr virus (EBV) major envelope glycoprotein gp350/220-specific antibody reactivities in the sera of patients with different EBV-associated diseases.

gp350 of Epstein-Barr virus (EBV) induces a strong immune response in EBV-infected individuals, but relatively little is known about the clinical relevance of this response in patients with different EBV-associated malignancies and other diseases. Using our gp350-expressing cell clones, we studied gp350-specific humoral immune responses in the sera of individuals with nasopharyngeal carcinoma (NPC), chronic symptomatic EBV infection (CEI), Hodgkin's disease (HD), acute infectious mononucleosis (IM) and healthy EBV-seropositive individuals (HI). The titres of antibody-dependent cellular cytotoxicity (ADCC) antibodies were highest in HI followed by CEI, HD and NPC. EBV-neutralizing (NA) and gp350-specific IgG antibody profiles in these conditions were: CEI > HI > NPC > HD, whereas IgA titres were the highest in NPC sera followed by CEI and HD. The sera from IM patients were found to be negative for gp350-specific ADCC and IgA activities. Sera from HI were also negative for gp350-specific IgA. A significant positive correlation was found between serum gp350 IgA and viral capsid antigen IgA and a significant negative one between IgM and ADCC titres. High IgA titres were also found in CEI and EBV-genome positive HD in addition to NPC. Importantly, gp350-specific IgA titres were of prognostic value in NPC patients. Our data provide new insights about the clinical relevance of gp350-specific immune responses in these diseases.

Antibodies, Viral↗

PubMed1998

A relationship between 5-lipoxygenase-activating protein and bcl-xL expression in murine pro-B lymphocytic FL5.12 cells.

Inhibitors of 5-lipoxygenase-activating protein (FLAP) have been found to induce apoptosis. The current study examined the expression of FLAP and bcl family proteins and the induction of apoptosis in interleukin-3-dependent control and bcl-xL-overexpressing FL5.12 cell lines after treatment with MK886, a specific FLAP inhibitor. FL5.12 cells contained a substantial amount of FLAP protein and mRNA but surprisingly had no measurable 5-lipoxygenase protein or 5-, 12-, or 15-lipoxygenase activity. The basal level of FLAP protein in cells overexpressing bcl-xL was 70% less than in controls. FLAP disappeared 4 h after withdrawal of interleukin-3 in bcl-xL cells but not in control cells, which underwent apoptosis. A dose- and time-response study revealed that 5 nmol of MK886/10(6) cells was sufficient to induce apoptosis both in control and bcl-xL cells, respectively, but to different degrees. bcl-xL and bcl-2 proteins, but not bax or FLAP, were decreased by 4 h after 5 nmol of MK886/10(6) cells in both cell lines, although the higher levels of bcl-xL in overexpressors took longer to disappear. This early loss of bcl-xL and bcl-2 was not attributable to generalized proteolysis, as shown by Coomassie Blue staining and by the maintenance of bax. Caspase-3 was activated 2 h after MK886 treatment in control cells but not in bcl-xL cells. Inhibition of caspase-3 decreased MK886-induced apoptosis by 50% in control cells. Inhibition of this caspase after MK886 treatment was unable to prevent the loss of bcl-xL in control cells but did provide partial protection for the loss of the transfected form, but not the endogenous form, in overexpressing cells. These data indicate that MK886 induces extensive apoptosis that is partially caspase-3 dependent and may be related to a rapid loss of bcl-xL. Although caspase-3 inhibitors had no effect on the loss of bcl-xL, other caspases or protease systems may still be involved. The absence of 5-lipoxygenase in cells containing FLAP, the lower level of FLAP in bcl-xL cells, the apoptosis-inducing activity of MK886, and the rapid loss of bcl-xL and bcl-2 proteins after treatment with MK886 strongly indicate that FLAP has activities unrelated to lipoxygenase and suggest a possible functional or regulatory link between these proteins, which share similar subcellular localizations.

5-Lipoxygenase-Activating Proteins↗

PubMed1998

Amyloid beta-peptide possesses a transforming growth factor-beta activity.

Amyloid beta-peptide (Abeta) of 39-42 amino acid residues is a major constituent of Alzheimer's disease neurite plaques. Abeta aggregates (fibrils) are believed to be responsible for neuronal damage and dysfunction, as well as microglia and astrocyte activation in disease lesions by multiple mechanisms. Since Abeta aggregates possess the multiple valencies of an FAED motif (20th to 23rd amino acid residues), which resembles the putative transforming growth factor-beta (TGF-beta) active site motif, we hypothesize that Abeta monomers and Abeta aggregates may function as TGF-beta antagonists and partial agonists, analogous to previously described monovalent and multivalent TGF-beta peptide antagonists and agonists (Huang, S. S., Liu, Q., Johnson, F. E., Konish, Y., and Huang, J. S. (1997) J. Biol. Chem. 272, 27155-27159). Here, we report that the Abeta monomer, Abeta-(1-40) and its fragment, containing the motif inhibit radiolabeled TGF-beta binding to cell-surface TGF-beta receptors in mink lung epithelial cells (Mv1Lu cells). Abeta-(1-40)-bovine serum albumin conjugate (Abeta-(1-40)-BSA), a multivalent synthetic analogue of Abeta aggregates, exhibited cytotoxicity toward bovine cerebral endothelial cells and rat post-mitotic differentiated hippocampal neuronal cells (H19-7 cells) and inhibitory activities of radiolabeled TGF-beta binding to TGF-beta receptors and TGF-beta-induced plasminogen activator inhibitor-1 expression, that were approximately 100-670 times more potent than those of Abeta-(1-40) monomers. At less than micromolar concentrations, Abeta-(1-40)-BSA but not Abeta-(1-40) monomers inhibited proliferation of Mv1Lu cells. Since TGF-beta is an organizer of responses to neurodegeneration and is also found in neurite plaques, the TGF-beta antagonist and partial agonist activities of Abeta monomers and aggregates may play an important role in the pathogenesis of the disease.

Amino Acid Sequence↗

PubMed1998

Arachidonic acid metabolism by adult human osteoblast-like cells exhibits sexually dimorphic characteristics.

The eicosanoids, including prostaglandin E2 (PGE2) and other bioactive arachidonic acid metabolites, are important local mediators of bone remodeling. Presumably, the limited or excessive synthesis of the eicosanoids could compromise bone homeostasis. We have noted that the stimulated release of arachidonic acid by adult male donor derived human osteoblast-like (hOB) cells exceeded the stimulated release measured for female-derived hOB cells by 1.5-fold. Assays of PGE2 biosynthesis by cytokine-stimulated hOB cells also demonstrated a sex-linked difference, such that male hOB cell PGE2 production exceeded female cell production by 1.6-2.2-fold. The calcium-dependent cytoplasmic phospholipase A2 activity in subcellular fractions prepared from hOB cell homogenates was higher in both the cytosolic (1.6-fold) and particulate (1.5-fold) fractions from the male cells than in those prepared from female hOB cells, suggesting a molecular basis for the observed sexually dimorphic characteristics related to arachidonic acid metabolism by hOB cells. The relatively limited capacity of the female cells may limit needed intracellular and intercellular signaling during bone remodeling, thereby contributing to the development of bone pathology.

Adult↗

PubMed1998

Identification and differential regional expression of KOR-3/ORL-1 gene splice variants in mouse brain.

KOR-3, also known as ORL-1, is a member of the opioid receptor family, encoding the murine receptor for orphanin FQ/nociceptin. In the current studies we have identified five different splice variants of KOR-3 in mouse brain, three of which have not been previously reported. In addition to variants with a 15 bp deletion at the 3'-end of the first coding exon (KOR-3d) and an 81 bp insertion between the second and third coding exons (KOR-3e), three new variants with insertions of 34 (KOR-3a), 98 (KOR-3b), and 139 bp (KOR-3c) between the first and second coding exons have been obtained. The expression of the three variants in mouse brain varies markedly among brain regions with a distribution which is quite distinct from KOR-3 itself. Of greatest interest was the presence of high levels of KOR-3a in the striatum, a region with no demonstrable KOR-3, and in the cortex. KOR-3c was seen in the periaqueductal gray and hypothalamus, regions where KOR-3 predominated. The brainstem had similar levels of KOR-3, KOR-3a, and KOR-3d. In contrast, KOR-3d was most prominent in the cerebellum. KOR-3b levels were very low throughout.

Alternative Splicing↗