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Biomedical subjects

X C Ma

Publications and source records attributed to X C Ma.

At least 19 recordsLinked to original sources
PubMed1995

Cloning the P. falciparum gene encoding PfEMP1, a malarial variant antigen and adherence receptor on the surface of parasitized human erythrocytes.

Plasmodium falciparum-infected human erythrocytes evade host immunity by expression of a cell-surface variant antigen and receptors for adherence to endothelial cells. These properties have been ascribed to P. falciparum erythrocyte membrane protein 1 (PfEMP1), an antigenically diverse malarial protein of 200-350 kDa on the surface of parasitized erythrocytes (PEs). We describe the cloning of two related PfEMP1 genes from the Malayan Camp (MC) parasite strain. Antibodies generated against recombinant protein fragments of the genes were specific for MC strain PfEMP1 protein. These antibodies reacted only with the surface of MC strain PEs and blocked adherence of these cells to CD36 but without effect on adherence to thrombospondin. Multiple forms of the PfEMP1 gene are apparent in MC parasites. The molecular basis for antigenic variation in malaria and adherence of infected erythrocytes to host cells can now be pursued.

Amino Acid Sequence↗
PubMed1995

Percutaneous internal maxillary arterial embolization with ethylcellulose microspheres. Results in an animal model.

RATIONALE AND OBJECTIVES: To investigate the use of ethylcellulose microspheres as long-term and peripheral emboli for percutaneous maxillofacial arterial embolization. METHODS: Eight mongrel dogs were selected randomly for internal maxillary artery embolization with ethylcellulose microspheres. After embolization, angiographic, microangiographic, and histologic examinations were performed. RESULTS: Ethylcellulose microspheres were trapped in the peripheral arterioles from 24 hours to 6 months after embolization. Degenerative changes of maxilla, mandible, and dental pulp occurred after the embolization of the internal maxillary artery with the microspheres. No evidence of whole or focal necrosis of the bones and surrounding soft tissues was found between 24 hours and 6 months after embolization. CONCLUSION: Ethylcellulose microspheres can be used as an alternative long-term and peripheral embolic agent, with potential for percutaneous maxillofacial arterial embolization.

Angiography, Digital Subtraction↗
PubMed1995

Experimental maxillofacial arterial chemoembolization with encased-cisplatin ethylcellulose microspheres.

PURPOSE: To compare chemoembolization with conventional chemotherapy and explore the possibility of chemoembolization in the oral and maxillofacial region using encased-anticancer-drug microspheres. METHOD: Six mongrel dogs were divided into two equal groups, an experimental group undergoing maxillofacial arterial chemoembolization with cisplatin encased in ethylcellulose microspheres, and a control group undergoing the conventional chemotherapy with cisplatin. The peripheral venous cisplatin concentration and the cisplatin concentration at the local tissue were determined. RESULT: The experiment showed a significant difference in the peripheral venous cisplatin concentration between the two groups and between the time period. There was also a significant interaction between groups and time. The peak concentration in the experimental group appeared 12 to 24 hours after chemoembolization. The peak concentration in the control group appeared immediately after the anticancer drug was infused. There was a significant difference in the concentration in the local tissue between the two groups, when all time periods were aggregated. CONCLUSION: Compared with conventional chemotherapy, the maxillofacial arterial chemoembolization with cisplatin encased in ethylcellulose microspheres significantly decreases the cisplatin concentration in the peripheral venous circulation and increases the concentration in the local tissues, allowing for the possibility of target cancer therapy.

Animals↗
PubMed1994

Expression of HLA-class II antigen in gastric carcinomas. Its relationship to histopathological grade, lymphocyte infiltration and five-year survival rate.

To investigate whether the expression of HLA-DR antigen in gastric carcinomas is associated with the survival rate, we studied 70 cases of gastric carcinoma using a monoclonal antibody. Forty-seven cases (67%) stained positively, including 31 differentiated carcinomas, and 16 undifferentiated carcinomas. A close correlation was found between expression of HLA-DR antigen and differentiation of the tumor cells. Marked lymphocyte infiltration was seen in the HLA-DR antigen positive cancers. In advanced gastric cancers, the 5-year survival rate of patients with HLA-DR antigen positive cancers was significantly higher (67.5%) than that of patients with HLA-DR antigen negative cancers (40%). The data suggest that the expression of HLA-DR antigen in gastric carcinomas may reflect the degree of tumor cell differentiation, and influence the host immune response and prognosis.

Carcinoma↗
PubMed1994

[Tumor necrosis factor in synovial fluids of temporomandibular joint dysfunction syndrome].

With the MTT tetrazolium WEHI 164 clone 13 cell cytotoxicity assay, we measured TNF alpha (tumor necrosis factor) activity in synovial fluids of TMJDS (Temporomandibular joint dysfunction syndrome). We found no detected TNF alpha level from 5 patients with muscle dysfunction, raised TNF alpha levels from 5 of 11 patients with internal derangement and from 9 of 11 patients with organic destruction (osteoarthritis). The findings of biologically active TNF alpha in synovial fluids of TMJDS suggest that TNF alpha may play a role in the pathogenesis of TMJDS.

Adolescent↗
PubMed1994

[Magnetic resonance imaging of lateral pterygoid muscle in temporomandibular joint dysfunction syndrome].

Fifteen TMJS of fifteen normal controls and thirty TMJs of thirty patients with TMJDS were studied with head-coil MR imaging. T1 weighted oblique sagittal scanning in closed and opened mouth and T2 weighted oblique sagittal scanning in closed mouth were used to evaluate the lateral pterygoid muscle of the controls and the patients. The upper head of lateral pterygoid muscle was found shorter and straighter in opened mouth than that in closed mouth. It is suggested that the upper head is in the state of contraction in opened mouth. The same finding was also found in the patients with TMJDS in opened mouth. Edema and effusion in lateral pterygoid muscle were found in 80% patients with TMJDS on T2 weighted image.

Adolescent↗
PubMed1994

[Operative and pathological observations on secondary synovitis of temporomandibular joint dysfunction syndrome].

14 cases (16 joints) with temporomandibular joint dysfunction syndrome (TMJDS) were included in the present study. All the patients had severe pain of the joint for a long time and the conventional therapy was not effective. The operative and pathological findings of the 14 cases showed that synovitis secondary to microtrauma of the joint really existed and might be one of the reasons causing the severe pain of the joint in some patients with TMJDS.

Adult↗
PubMed1993

Expression of sialyl-Tn antigen is correlated with survival time of patients with gastric carcinomas.

Expression of sialyl-Tn antigen (STN) was examined by an immunohistochemical method in 85 primary gastric carcinomas. The STN expression occurred in 53 (62.4%) cancers, and the positive staining was correlated with degree of gastric wall and lymph vessel invasion, lymph node metastasis, and stage of tumour. Five-year survival rates of patients with STN-positive cancers (47.2%) were significantly lower than those with STN-negative cancers (84.4%) (P < 0.01), and patients with STN-positive cancers at stage III and stage IV had a worse prognosis. In the cancers with serosal invasion, patients with STN-positive cancer disclosed a significantly poorer prognosis than those with STN-negative cancers (P < 0.01). Therefore, it is suggested that a careful follow-up study and intensive postoperative therapy are needed for patients with advanced gastric cancers with positive STN expression.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1993

Recurrent parotitis in adults. Report of 35 cases.

Clinical, laboratory and sialographic findings were studied in 35 adult patients with recurrent parotitis. The patients were followed up for 0.5-23 years. The results showed that sialographic recovery occurred 3-5 years after disappearance of clinical symptoms. Recurrent parotitis is not a autoimmune disease, and remission may take place spontaneously, including clinical and sialographic healing. However, marked degeneration of the parotid gland or chronic obstructive parotitis may develop consequently. The differential diagnosis of recurrent parotitis in adults is also discussed.

Adolescent↗
PubMed1992

[Analysis of erroneous diagnosis on temporomandibular joint arthrography].

In the present study, 433 arthrographic cases with temporomandibular joint dysfunction syndrome were included. 30 cases of them underwent operation and 22 cases underwent digital subtraction arthrographic examination after conventional arthrography. It has been found that arthrographic erroneous diagnosis could be made because the artificial manifestations caused by over-dose of contrast medium into the joint cavity, repeated puncture, anterior displacement of the condyle after injecting contrast medium and so on. In addition, the arthrographic manifestations of dis-clock were also analysed.

Adolescent↗
PubMed1992

[Evaluation of digital subtraction arthrography on the diagnosis of temporomandibular joint dysfunction syndrome].

Digital subtraction arthrography of temporomandibular joint superior cavity (TMJSC-DSA) was performed for 70 cases with TMJ dysfunction syndrome. A comparative observation between the operative findings and the findings of TMJSC-DSA examination was carried out for 11 cases who underwent TMJ operation. The results showed that TMJSC-DSA could overcome the disadvantages of conventional arthrography and make exact diagnoses for the anterior displacement of the disc and the disc perforation.

Adolescent↗