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Biomedical subjects

X Ma

Publications and source records attributed to X Ma.

At least 325 records · Page 18Linked to original sources
PubMed1995

[Investigation on scoliosis incidence among 24,130 school children].

Through the screening on scoliosis among 24,130 school children in Hu Guan County, Shanxi Province, it showed that the forward-bending test was positive in 1,794 children (7.4 per cent), with male 3.64 per cent and female 3.8 per cent. The hump inclination angles that were more than 4 degrees were found in 665 children (2.75 per cent). The Cobb angles that were more than 10 degrees were found in 347 children. The incidence rate was 1.44 per cent, with a male to female ratio of 1:1.17. Most of them were idiopathic scoliosis.

Adolescent↗
PubMed1995

PDI-, PPI- and chaperone-catalyzed refolding of recombinant human IL-2 and GM-CSF.

The studies on PDI-, PPI- and chaperone-catalyzed refolding of recombinant human IL-2 and GM-CSF show that PDI can prevent the mismatch of disulfide bonds and formation of aggregates by interchains linkage; furthermore, PDI can correct the mismatching of disulfide bonds in IL-2 isomers. PPI can increase the rate of folding reaction while chaperone can prevent the aggregation during the folding process. In addition, there is a synergistic effect between them.

Amino Acid Isomerases↗
PubMed1995

Expression of human interleukin-11 cDNA in E. coli.

A 551-bp hIL-11 gene fragment that includes no nucleotide sequences encoding signal polypeptide and the initial 8 amino acids of the mature protein was cloned into a high-level expression vector pEx31B of E. coli. The authors identified the recombinant plasmid, designated pEx31-IL11, by restriction endonucleases digestion and DNA sequencing. The resulting recombinant plasmids were then used to transform E. coli strain HB101, and expression in the PL promoter system, which is temperature-regulated, was achieved. The expressed fusion protein amounts to 50% of total bacterial proteins. The hIL-11 protein expressed in E. coli was fused to the N-terminal 99 amino acids of the MS2 polymerase to form the inclusion body. These recombinant proteins can be purified to about 80% by extracting inclusion body with urea. One IL-6-dependent cell line 7 TD1 was used for bioassay. The recombinant hIL-11 protein was preliminarily purified and renatured to a specific activity of 10(5)U/mg, even in the presence of an excess of a neutralizing anti-IL-6 antibody.

DNA, Complementary↗
PubMed1995

Modulation of retinoblastoma and retinoblastoma-related proteins in regenerating rat liver and primary hepatocytes.

Protein expression of the retinoblastoma (Rb) tumor suppressor gene product was examined by immunoblot analysis of nuclei isolated from regenerating rat liver after 70% partial hepatectomy (PH). Levels were almost undetectable in quiescent 0-h livers but increased 15- to 60-fold 3 to 24 h post-PH, 105-fold at 30 h, and 20- to 50-fold at 60 to 72 h post-PH. Expression returned to near baseline levels at 18, 42, and 48 h post-PH. A similar pattern of Rb protein expression in the regenerating liver was observed by indirect immunofluorescence microscopy, with peak nuclear expression at 30 h post-PH. Rb-related proteins with apparent molecular masses of 300, 156, and 74 kDa were detected in regenerating liver using mAbs to the Rb protein. Their expression increased 6- to 8-fold during regeneration, and only p156 returned to baseline levels at 60 h post-PH. Rb and its related proteins were detected in cultured primary hepatocytes, and although total protein levels did not change appreciably, there was a dramatic shift from cytosol into nuclei through 96 h. The half-life of the Rb protein was determined to be 1.9 h in regenerating liver and 2.2 h in cultured primary hepatocytes. Rb protein abundance in synchronized HuH-7 human hepatoma cells was cell cycle dependent and exhibited peak nuclear expression during S phase. Rb protein was detected primarily in its hyperphosphorylated state during liver regeneration and through the cell cycle of the HuH-7 cells. In vivo administration of transforming growth factor beta 1, an inhibitor of DNA synthesis in regenerating liver, resulted in reduced expression of Rb as well as its protein partners, cell cycle-dependent kinase 4 and cyclin E. The results suggest that in the regenerating rat liver and in synchronized HuH-7 cells, expression of Rb protein is modulated in a cell cycle-dependent fashion, remains primarily in a hyperphosphorylated state, and exhibits a relatively short half-life. The inhibition of Rb protein expression by transforming growth factor beta 1 may be linked to its simultaneous suppression of cell cycle-dependent kinase 4 and cyclin E protein levels.

Animals↗
PubMed1995

Purification of recombinant human granulocyte-macrophage colony stimulating factor expressed in Escherichia coli.

Recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) was expressed as inclusion bodies (IB) in E. coli. A simple and effective protocol has been worked out for the purification. IB collected after the breakage of bacteria through sonication were subjected to repeated washing followed by solubilization in TE buffer (50 mmol/L of Tris.HCl, 1 mmol/L of EDTA, pH 8.3) containing 8 mol/L urea and 10 mmol/L DL-dithiothreitol. By means of Sephacryl-200 HR, refolding, and Q Sepharose Fast Flow, rhGM-CSF was obtained with a purity of 99%. The total protein recovery was 10% and specific activity of rhGM-CSF was 1 x 10(7) u/mg. The sequence of N-terminal 16 amino acid residues of purified rhGM-CSF was determined and found to be identical to the native protein. This study provided useful parameters for mass production of rhGM-CSF.

Amino Acid Sequence↗
PubMed1995

[Effects of occlusal trauma on temporomandibular joints in rabbits: a scanning electron microscopic study].

Six rabbits with unilateral occlusal splints on the mandibular left molars for one month, three months or five months were examined to study the ultrastructure of the surface of the temporomandibular joint. Four rabbits were used as control. The results showed that the surface layer of the disk and articular cartilage were damaged. Severe fibrillation with sheets of fibers, collagen fibrils and collagen bundles inside fissures and craters were observed. These changes were seen in all rabbits with occlusal trauma and also in control rabbits for five months. The findings suggested that occlusal trauma could result in degenerative changes of the temporomandibular joint.

Animals↗
PubMed1995

[Relationship between the rate of parasitic infection and the knowledge of prevention].

The relationship between the rate of parasitic infection and the level of knowledge of prevention was studied among 5479 persons allocated to 12 randomly selected groups. Stools were examined for parasitic infection by using Kato-Katz, iodine direct smear amd tube culturing methods. Children under 15 were examined for Enterobius infection by cellophane tape method. Individuals were considered infected when any parasite species was found in the stool and the infection rate was computed. The score on knowledge of prevention was measured by devising a questionnaire comprising 11 questions on parasitic disease transmission, clinical signs and prevention methods. Ten marks were given for each question correctly answered. The result of the investigation showed that the total infection rate was 52.2% and there was no significant difference between males and females (X2 = 1.94, P > 0.05). The infection rate increased with a decrease in the level of education and the highest was found in 5-year-old age group. There were altogether 7 species of parasites detected in all age groups. The infection rate of Ascaris lumbricoides was 31.3%; Trichuris trichiura, 34.1%; hookworm, 5.3%; Enterobius vermicularis, 20.3%(227+1 117); Fasciolopsis buski, 0.8%; Entamoeba coli, 0.8%; Giardia lamblia, 0.2%. The average score on knowledge was 41.9, being significantly higher in males than in females. Analysis for the age distribution showed that the highest score was found in 15-year-old age group. The data of infection rate of different parasites were converted by arcsine transformation and compared with the average score, showing that there were negative relations between the average score and the infection rate of Trichuris, hookwork, Entamoeba and the total incidence. The value of r was --0. 5534, --9.5557, --0.6091 and --0.604. respectively. The number of parasite species infecting individuals was also found to have negative relation to the score on knowledge of prevention.

Adolescent↗
PubMed1995

[Hepatitis B virus infection and pathogenesis of glomerulonephritis].

In order to investigate the role of hepatitis B virus (HBV) infection in the pathogenesis of HBV associated glomerulonephritis, 50 cases of glomerulonephritis with positive HBV infection marker antigenemia and/or HBAg detected by immunohistochemistry in renal tissue were collected. The distribution and localization of HBV DNA were observed by using in situ hybridization. In addition, Southern blot analysis was performed in 23 of the 50 cases to reveal the state of renal HBV DNA. Thirty Six cases (72%) were found to be HBV DNA positive by in situ hybridization, which was localized in the nucleus of tubular cells. In 26 cases HBV DNA was simultaneously detected in the nucleus of glomerular mesangial and epithelial cells as well as in the mesangial matrix. Seventeen of the 23 cases proved to be HBV DNA positive by Southern blot analysis. In which 3 cases were identified as having non-replicating free HBV DNA, while 14 cases (82%) were of the integrated form. Since there was abundant evidence of the renal tissue being infected with HBV, it was considered that the HBAg deposited on glomeruli not only originated from circulation but also from the HBV infected glomerular cells. In addition to the humoral immune injury mediated by HBAg-HBAb immune complex, the cellular mechanism mediated by target antigen (HBcAg) may be also involved in the pathogenesis of HBV associated glomerulonephritis.

Blotting, Southern↗
PubMed1995

[Evaluation of the condylar position in the diagnosis of temporomandibular joint dysfunction syndrome].

26 cases with Temporomandibular Joint Dysfunction Syndrome (TMJDS) were included in the present study. Fully corrected lateral tomogrames of TMJ in the intercuspid position were taken for all the cases; and fully corrected lateral arthrotomogrames were taken for 19 cases (21 joints) of them. The area and linear measurements of the joint space were made with the aid of computer. The results showed that the position of the condyle in the patients with TMJDS was located in the posterior position of the fossa. Statistics results showed that there was significant difference between the patient group and control group. Although the posterior displacement of the condyle was often associated with the anterior displacement of the disc, it was not always agreement with the anterior disc displacement. So, the exact diagnosis of disc displacement should be still on the basis of arthrography or other examinations, such as CT or MRI.

Adolescent↗
PubMed1995

[Interleukin-6 activity in synovial fluids of temporomandibular joint distrubance syndrome].

Using the IL-6-dependent mouse hybridoma cell line KD 83, IL-6 biological activity in synovial fluids of the patients with Temporomandibular Joint Disturbance Syndrome (TMJDS) was tested. The results show that IL-6 level is high in 13 cases of 18 patients with TMJ degenerative changes and 5 cases of 12 patients with TMJ Disc Displacement. IL-6 level is less than 100 U/ml in all patients with Masticatory Muscle Disorder (59.4 +/- 29.4 U/ml). In addition, it has been found that TMJDS tends to have acute and chronic stages and IL-6 is probably related to acute stage of the patients.

Adolescent↗
PubMed1995

Cloning, expression and purification of the ligand-binding region of human IL-6R in E. coli and its preliminary functional identification.

The ligand-binding region of human IL-6R is taken as the target gene fragment to be cloned and expressed. With pET-3b as expressing vector, two recombinants pET-6R(B) and pET-6R(B)4 have been constructed encoding the ligand-binding region (28 kD) of hIL-6R and its dimmer (53 kD), respectively. After induction with IPTG, they produced two proteins rIL6R-28 of 28 kD and rIL6R-53 of 53 kD amounting to 50% and 30% of total bacteria proteins, respectively. The expressed products were mainly recovered as inclusion bodies. After purification and renaturation, both of them were capable of augmenting the growth-stimulating effect of IL-6 on 7TD1 cells, an IL-6 dependent cell line. The result of ELISA also revealed that both rIL6R-28 and rIL6R-53 had the obvious ligand-binding activity.

Antigens, CD↗
PubMed1995

[Clinical application prospect of digital subtraction technique for periapical radiographs].

The composition and functions of digital subtraction system for conventional radiographs were introduced. Based on the experimental test for this system, it has been found that digital subtraction system for conventional radiographs is very valuable for the diagnoses of minute bone lesions in the bifurcation, root side and apical part of the teeth as well as in the alveolar crest. In addition, the reproducibility of the projection geometry, the principle of digital subtraction and its clinical application prospect are also discussed in the present paper.

Humans↗
PubMed1995

[Histopathologic classification of 1921 orbital tumors].

PURPOSE: The retrospective study is undertaken to determine the histopathologic types of space-occupying lesions of the orbit in 1921 cases examined between 1953-1992 at the Eye Pathology Laboratory of Shanghai Medical University. METHODS: The authors reviewed old diagnostic pathologic slides on file including HE stain as well as special stains, if available, for all the indeterminate cases. Newly prepared immunohistochemical stains are made for the controversial cases to help diagnosis. Some slides are discussed and diagnosed by Pathology Slide Meeting of the Shanghai Surgical Pathology Society. Cases with diagnosis not agreed upon by the pathology meeting are excluded from this study. RESULTS: The 5 leading malignant orbital tumors are malignant lacrimal gland tumors (138 cases, 32%), malignant lacrimal sac tumors (112 cases, 26%), rhabdomyosarcomas (65 cases, 15%), lymphosarcomas (56 cases, 13%), and malignant hemangiopericytomas (31 cases, 7%). The 5 leading benign orbital tumors are cavernous hemangionas (411 cases, 36%), dermoid cysts (152 cases, 13%), benign mixed tumors (150 cases, 13%), inflammatory pseudotumosr (129 cases, 11%), and schwannomas (92 cases, 8%). Rare tumors of the orbit include alveolar soft tissue sarcoma, chondrosarcoma, mesenchymal chondrosarcoma, synovial sarcoma, giant cell tumor, granular myoblastoma, yolk sac tumor, and retinal anlage tumor. CONCLUSION: This study, in agreement with other reports of the statics study of the orbital tumors demonstrates the prevalence of hemangiomas, lacrimal gland tumors and lymphoid pseudo-tumors to be the common space-occupying lesions in the orbit. Some rare tumors are discussed.

Hemangioma, Cavernous↗
PubMed1994

Impaired interleukin 12 production in human immunodeficiency virus-infected patients.

Peripheral blood mononuclear cells (PBMC) from human immunodeficiency virus (HIV)-infected patients, asymptomatic or with acquired immunodeficiency virus, produced 10-fold less interleukin 12 (IL-12) free heavy chain and fivefold less biologically active IL-12 heterodimer than PBMC from uninfected healthy donors when challenged in vitro with the common human pathogen Staphylococcus aureus. In contrast, PBMC from HIV-infected individuals and uninfected control donors produced similar levels of tumor necrosis factor alpha, IL-1 beta, and IL-10, and PBMC from HIV-infected individuals produced three- to fourfold more IL-6 compared with PBMC from uninfected control donors. The defect in IL-12 production is not due to hyperproduction of IL-10, a cytokine exerting an autocrine-negative feedback on IL-12 production, but was directly related to HIV infection, as suggested by the reduced ability of monocytes infected in vitro with HIV to produce IL-12. IL-12 deficiency may be an important component of the immunodeficiency associated with HIV infection.

Adult↗
PubMed1994

Dose-response relationships in mice following subchronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin: CYP1A1, CYP1A2, estrogen receptor, and protein tyrosine phosphorylation.

The dose-response relationships for different endpoints in different tissues were compared in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment. TCDD was administered 5 days a week for 13 weeks at doses ranging from 1.5 to 150 ng/kg/day to female B6C3F1 mice. Ethoxyresorufin-O-deethylase (EROD) activity, a marker for CYP1A1, was increased in liver, lung, and skin at doses as low as 1.5 ng/kg/day. EROD activity did not attain maximal induction. Liver acetanilide-4-hydroxylase activity, a marker for CYP1A2, was significantly induced at 1.5 ng/kg/day and reached maximal induction at 45 ng/kg/day. TCDD treatment significantly increased the amount of phosphorylated forms of three phosphotyrosyl proteins (pp32, pp34, and pp38) in liver S-20 fractions. Changes in these phosphotyrosyl proteins occurred at 1.5 ng/kg/day and reached maximal induction at 4.5 ng/kg/day. No changes in phosphotyrosyl proteins were observed in skin. Hepatic and uterine estrogen receptor levels were not altered at any of the doses tested. These data indicate that induction of CYP1A1, CYP1A2, and the increases in phosphorylated forms of pp32, pp34, and pp38 are sensitive indicators of TCDD exposure. The dose-response curves for increases in CYP1A1, CYP1A2, and phosphorylated pp32, pp34, and pp38 in liver were different from each other. TCDD produces multiple effects with multiple dose-response curves suggesting that there are events in addition to receptor binding that are endpoint specific, leading to different dose-response relationships.

Animals↗
PubMed1994

Cytotoxic clerodane diterpenes from Polyalthia barnesii.

Three cytotoxic clerodane diterpenes were purified from an ethyl acetate-soluble extract of the stem bark of Polyalthia barnesii, namely, 16 alpha-hydroxycleroda-3,13(14)Z-dien-15,16-olide, a known compound, and two novel compounds, 3 beta, 16 alpha-dihydroxycleroda-4(18),13(14)Z-dien-15,16-olide and 4 beta, 16 alpha-dihydroxyclerod-13(14)Z-en-15,16-olide. These compounds were found to exhibit broad cytotoxicity against a panel of human cancer cell lines.

Antineoplastic Agents, Phytogenic↗