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Biomedical subjects

Z Ma

Publications and source records attributed to Z Ma.

At least 181 records · Page 10Linked to original sources
PubMed1997

Explaining hierarchical and interprovincial migrations of Chinese young adults by personal factors and place attributes: a nested logit analysis.

"This paper uses a two-level nested logit model to explain the inter-stratum (city, town and rural county) and interprovincial migration behaviors of the young adults (aged 17-29) in China during a three-year period (1985-87), based on the micro data of the 1987 National Population Survey. The migration propensity of each person is represented by a departure probability and a destination choice probability. These probabilities are then expressed as functions of personal factors and place attributes. The main findings are that personal factors are of paramount importance in explaining the departure behaviors, and that both departure and destination behaviors responded to market forces in a sensible way, despite government control on territorial movements."

Asia↗
PubMed1997

Mutation of Arg154 to Gly154 in urokinase augments its fibrin-specificity.

Rscu-PA and its mutant constructed by in vitro site specific mutagenesis of Arg154 in rscu-PA to Gly154 (mscu-PA) were both expressed in Escherichia coli. After in vitro denaturation and renaturation, the rscu-PA and mscu-PA were purified to homogeneity by Zn2+ selective precipitation, anti-u-PA IgG-sepharose CL 4B affinity chromatography. After activation by plasmin, the kinetic constants for the resultant mtcu-PA against synthetic substrate S2444 hydrolysis were found to be essentially identical to rtcu-PA, suggesting that no impairment had been exerted on the catalytic active site of mtcu-PA. However, both 125I-fibrin plasma-clot lysis and fibrinogenolysis showed that mtcu-PA possessed a higher fibrinolytic activity but hardly any degradation of fibrinogen in plasma compared to rtcu-PA and rscu-PA. It was concluded that the substitution of Arg154 by Gly154 in tcu-PA promoted the fibrin-specificity of urokinase.

Arginine↗
PubMed1997

Potassium currents in atrial and ventricular myocytes from a rat model of cirrhosis.

The underlying mechanisms for the electrophysiological abnormalities that develop as a consequence of cirrhosis of the liver have been studied by recording three different K+ currents in mammalian heart tissue. Single myocytes from the atria and ventricles of sham-operated and bile ductligated (BDL) cirrhotic adult rats were current and voltage clamped using standard whole cell methods. In ventricular myocytes from cirrhotic animals, measurements of the current-voltage relationships, voltage dependence of inactivation, and reactivation kinetics of K+ currents showed that the only significant functional changes (within the physiological range of membrane potentials) were decreases in the density of expression of 1) I(t), a Ca(2+)-independent transient outward K+ current, and 2) Isus, a delayed rectifier K+ current. The decreases in I(t) and Isus contribute to the prolonged Q-T interval of the electrocardiogram that has been described in cirrhotic patients. Measurement of K+ currents in atrial myocytes demonstrated that there were no significant differences in any of the K+ current densities between sham and BDL animals, although reactivation kinetics of I(t) were slowed somewhat.

Animals↗
PubMed1997

[Correction of lower extremity deformity by unilateral axial dynamic fixator].

Seventy-eight limb segments with various lower extremity deformity in 60 cases were treated by unilateral axial dynamic fixator (UADF). Bone healing of 77 osteotomy sites was primary union. One site was delayed union. The correction of limb axial line and recovery of joint function were excellent. The incidence of pintrack infection was 0.6%. The advantages of this device were minimum injury, simple procedures, stable fixation and reliable correction of deformity, promotion of callus formation and ossification by elastic fixation, less joint functional effect, and rare complication. The advandage of this method is that limb deformity can be adjusted to an ideal shape by using UADF. The average follow-up for 2.5 years indicated that application of UADF is an alternative method for the treatment of genu varus, genu valgus, and malunion of fracture.

Adolescent↗
PubMed1997

[Detection of MLL gene rearrangement in acute myelomonocytic and monocytic leukemia].

OBJECTIVE: To reveal the incidence of MLL gene rearrangement and its clinical, features in acute myelomonocytic leukemia (M4) and acute monocytic leukemia (M5). METHODS: 10 patients with M4 and 27 cases with M5 were studied with the Southern blot technique to detect MLL gene abnormalities. RESULTS: 5 M5 patients were found to have MLL rearrangement, and these patients were characterized clinically by: (1) Younger at onset, (2) a higher white blood cell count (often > 100 x 10(9)/L), (3) frequent extramedullary involvement with hepatosplenomegaly and central nervous system leukemia (CNSL), and (4) a lower remission rate with a short survival time. CONCLUSION: There is a high incidence of MLL rearrangement in M5, and this gene abnormality stands for a marker of poor prognosis.

Adolescent↗
PubMed1997

[Active constituents reducing side-effects of prednisone acetate in leaves of Panax ginseng C.A.Mey].

The rise of total lipid, triglyceride and total cholesterol, and the drop of cortisol in serum induced by PA can be significantly inhibited by total ginsenosides in the leaves of Panax ginseng [GSL, 60 mg/(kg.d)]. From GSL ten compounds have been isolated and identified as ginsenoside-Rb2, -Rc, -Rd, -Re, -Rg1 -F3, F2, -Rg2, 20(R)-Rg2 and -Rh1, respectively. Pharmacological study has proved ginsenoside-Re to be the chief active constituent of GSL.

Animals↗
PubMed1997

[The preparation of poly (DL-lactide) hollow fiber and the release of drug in vitro].

The biodegradable hollow fibers of DL-PLA were prepared by a dry-wet phase inversion spinning process. By using four different spinning systems, DL-PLA hollow fibers with varying asymmetric membrane structure were obtained. The structure of hollow fiber wall was examined by SEM. In vitro release of norethisterone from the DL-PLA hollow fibers was also investigated. The hollow fibers were filled with a 50 wt% NET in castor oil. The DL-PLA hollow fibers NET release was found to be dependent on the membrane structure of the hollow fiber wall. Possible release mechanisms were discussed.

Delayed-Action Preparations↗
PubMed1997

Study on small hepatocellular carcinoma and its extension.

This paper summarizes the "study on small hepatocellular carcinoma and its extension" in Liver Cancer Institute, Zhongshan Hospital of Shanghai Medical University during the past 25 years. The results indicated that it was an important approach to obtain long-term HCC survivors, of the 239 patients with 5-year survival, small HCC resection accounted for 51.4%. It was an effective approach to improve the prognosis of HCC in the entire series, the 5-year survival of inpatients treated in authors' institution was 4.8% in 1958-1970, 12.2% in 1971-1983, and 46.7% in 1984-1995; which were correlated to the increase proportion of small HCC resection in the series; it was more effective as compared to large HCC resection, the 5 year survival was 61.3% (n = 645) versus 33.6% (n = 950). Extensions of small HCC study included early detection and treatment of small recurrent HCC, of the 147 patients with re-resection, the 5-year survival was 48.9% calculated from the time of first resection. Another extension was conversion of large HCC into small HCC, using multimodality combination treatment, 72 out of the 663 patients with surgically verified unresectable HCCs have been converted to resectable, 5-year survival being 62.1%, which was comparable to that of small HCC resection. Studies on related basic aspect of small HCC such as cell origin of recurrence, and molecular aspect of small HCC, indicated that biological characteristics, particularly the tumor invasiveness, remained the key link for further prolong survival after small HCC resection. Recently, a "patient-like" human HCC metastatic model in nude mice has been established. Experimental interventions have also been tried. Clinical trials for prevention of recurrence after small HCC resection have shown preliminary encouraging results. However, the "cost-effectiveness" of screening, the invasiveness of HCC, the multicentric origin, the coexisted Child C cirrhosis, etc., remained great challenge.

Animals↗
PubMed1997

[Application of mean EMG to the evaluation of human workload during manual operation].

To evaluate human workload during manual operation, 9 subjects participated in the attitude maintaining experiment with simulated earth scenery as the display and a stick as the controller. Mean-rectified EMG was chosen as the index. Surface EMG was recorded in a couple of agonist and antagonist. Kinematics equation was simulated on a analog computer, and three difficulty of work were controlled by changing the amplifier's coefficients. 486 Computer was used to record the quantity of subject's operation and the data of Mean EMG from amplifier. Relevant software was compiled. The results showed that there was a linear relationship between mean-rectified EMG and difficulty of work. The effects of training on workload were also discussed. Mean EMG can be used as an index for evaluating human workload.

Electromyography↗
PubMed1997

Effect of hemoglobin- and Perflubron-based oxygen carriers on common clinical laboratory tests.

Polymerized hemoglobin solutions (Hb-based oxygen carriers; HBOCs) and a second-generation perfluorocarbon (PFC) emulsion (Perflubron) are in clinical trials as temporary oxygen carriers ("blood substitutes"). Plasma and serum samples from patients receiving HBOCs look markedly red, whereas those from patients receiving PFC appear to be lipemic. Because hemolysis and lipemia are well-known interferents in many assays, we examined the effects of these substances on clinical chemistry, immunoassay, therapeutic drug, and coagulation tests. HBOC concentrations up to 50 g/L caused essentially no interference for Na, K, Cl, urea, total CO2, P, uric acid, Mg, creatinine, and glucose values determined by the Hitachi 747 or Vitros 750 analyzers (or both) or for immunoassays of lidocaine, N-acetylprocainamide, procainamide, digoxin, phenytoin, quinidine, or theophylline performed on the Abbott AxSym or TDx. Gentamycin and vancomycin assays on the AxSym exhibited a significant positive and negative interference, respectively. Immunoassays for TSH on the Abbott IMx and for troponin I on the Dade Stratus were unaffected by HBOC at this concentration. Tests for total protein, albumin, LDH, AST, ALT, GGT, amylase, lipase, and cholesterol were significantly affected to various extents at different HBOC concentrations on the Hitachi 747 and Vitros 750. The CK-MB assay on the Stratus exhibited a negative interference at 5 g/L HBOC. HBOC interference in coagulation tests was method-dependent-fibrometer-based methods on the BBL Fibro System were free from interference, but optical-based methods on the MLA 1000C exhibited interferences at 20 g/L HBOC. A 1:20 dilution of the PFC-based oxygen carrier (600 g/L) caused no interference on any of these chemistry or immunoassay tests except for amylase and ammonia on the Vitros 750 and plasma iron on the Hitachi 747.

Animals↗
PubMed1997

Biological and clinical significance of cytogenetic study on 100 acute lymphoblastic leukemia and 219 acute non-lymphoblastic leukemia.

OBJECTIVE: To further investigate the role that cytogenetic may play in the diagnosis and prognosis of leukemia, a study was conducted in 319 acute leukemias. METHODS: 100 patients with acute lymphoblastic leukemia (ALL) and 219 patients with acute non-lymphoblastic leukemia (ANLL) were from Rui Jin Hospital, Xin Hua Hospital, Ren Ji Hospital and Shanghai Children's Hospital. Their cytogenetic data were analyzed together with those of morphology, immunology and clinical prognosis. RESULTS: In ALL group, 48 cases were karyotypically normal whereas 52 cases revealed chromosomal changes, among which 32 had quantitative abnormalities and 20 had qualitative abnormalities. The translocation t(9; 22) was identified in 11 out of 20 cases of structural aberrations (55%). Specific structural aberrations t(9; 22) and t(8; 14) were detected to be related to B-lineage associated differentiation antigens and t(8; 14) also with ALL-L3 according to FAB classification. With regard to clinical prognosis, the survival rate of structural aberration subset decreased significantly compared with the normal karyotype subset (P < 0.05). However, no statistically significant difference was found between hyperdiploidy subset (not including near-triploidy) and normal karyotype subset (P > 0.75). In ANLL group, 80% of de novo patients and relapsed patients had chromosomal abnormalities. Importantly, structural aberrations accounted for 73% of these abnormalities and frequently corresponded to specific types of FAB classification. Relevant prognostic studies demonstrated that t(15; 17) subset had the best overall survival probability, followed by t(8; 21) and normal karyotype subset, while the numerical aberration subset showed a relatively poor prognosis. CONCLUSION: Our data confirmed that cytogenetic study is important for the molecular study of the leukemogenesis. On the other hand, it also provides an independent parameter for prognosis in acute leukemia.

Adolescent↗
PubMed1997

[Clinical features of hemangioblastomas of the central nervous system].

OBJECTIVE: To study the clinical features of hemangioblastomas of the central nervous system (CNS). METHODS: 174 patients with hemangioblastomas of CNS were reviewed from 1982 to 1995. All patients were verified pathologically. RESULTS: The tumors occurred mainly in patients between 21 and 40 years of age, and more often in men than in women. Most tumors were in the posterior fossa. CT scan of 119 patients showed that 95 hemangioblastomas appeared as cysts. Magnetic resonance imaging (MRI) for 47 patients showed that 32 had cysts. 49 patients were examined with angiography or DSA. 164 tumor mural nodules and solid masses were completely resected. The subtotal removal of others was performed. These patients received radiotherapy. CONCLUSION: Enhanced MRI is the examination of choice for preoperative evaluation of cystic hemangioblastomas. Angiography or DSA is necessary in the diagnosis of bigger solid masses. The findings suggest that patients' age and degrees of section could affect the recurrence of hemangioblastoma.

Adolescent↗
PubMed1997

High-level expression and purification of human pro-UK cDNA in Escherichia coli.

A chemically synthesized human pro-urokinase (pro-UK) CDNA was cloned into the expression vector PET-11d and expressed in E. coli BL21(DE3) pLysS under the control of the T7 promoter. Using 0.1 mmol/L IPTG induction, the expression level of the recombinant pro-UK attained up to 15% of the total bacterial proteins and existed as inclusion bodies. After denaturation and renaturation in vitro, the expressed pro-UK was purified to be identified by Zn2+ selective precipitation, immuno-affinity chromatography, and benzamidine affinity adsorption. The specific activity of the purified human pro-UK was about 110,000 IU/mg.

Cloning, Molecular↗
PubMed1997

[Tumours of the nose and sinuses presented as nasal polyp].

Twelve cases of tumours of the nose and sinuses misdiagnosed at the first time as nasal polyp are reported. Of them, 4 were benign and 8 malignant. The endoscopic technique is helpful to differential diagnosis of benign or malignant lesions and polyps in these areas.

Adult↗
PubMed1997

[Gamma knife treatment of brain metastatic tumors].

Twenty-one cases of brain metastases including 46 tumors treated with Gamma knife (GK) from Sep. 1995 to July 1996 were reported. Among them, 4 patients died within one month, 17 patients with 29 tumor masses were followed up by MRI or CT. The rate of local control was 93%. The total mortality was 19%. The GK treatment associated mortality was 4.7%. Karnofsky Performance Status (KPS) stabilized in 3 cases, improved in 12 cases, regressed in 2 cases. One patients was operated due to the increase of the tumor volume. Four patients were treated with GK again due to the new lesions. The indications of GK treatment of the brain metastases, dose planning, and efficacy were discussed in brief.

Adult↗