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Biomedical subjects

Z Xu

Publications and source records attributed to Z Xu.

At least 433 records · Page 24Linked to original sources
PubMed1996

Sodium 2,3-dimercaptopropane-1-sulfonate challenge test for mercury in humans. III. Urinary mercury after exposure to mercurous chloride.

The sodium salt of 2,3-dimercaptopropane-1-sulfonic acid (Dimaval; DMPS) challenge test has been given previously to humans exposed to elemental mercury (vapor) or mercuric salts, but not mercurous salts. The test (300 mg p.o., after an 11-hr fast) was given to 11 factory workers who make a skin lotion that contains mercurous chloride, eight users of the skin lotion and nine controls. Urines were analyzed for total mercury by using cold vapor atomic absorption spectrophotometry. The mercury excreted for 6 hr before and 6 hr after DMPS treatment was 113 micrograms +/- 26 and 5037 micrograms +/- 682 S.E.M. for the skin lotion makers; 16.2 micrograms +/- 3.4 and 1410 micrograms +/- 346 S.E.M. for the skin lotions users; and 0.49 micrograms +/- 0.11 and 18.4 micrograms +/- 7.1 S.E.M. for the controls, respectively. The increases in urinary mercury resulting from the DMPS challenge test were 45-, 87- and 38-fold, respectively. The results demonstrate that, in humans exposed to mercurous chloride, DMPS increases the urinary excretion of mercury and that the DMPS/mercury challenge test is of value for a more realistic estimation of mobilizable mercury. An attempt to associate genotoxicity, as indicated by micronuclei content in buccal cells, with mercury exposure was inconclusive, perhaps because of the small number of subjects.

Adult↗
PubMed1996

Evaluation of the redox tolerance index on hepatic energy reserve of hepatitis B patients.

OBJECTIVE: To detect the redox tolerance index (RTI) for hepatic energy reserve. PATIENTS AND METHODS: 27 patients with chronic active hepatitis B (CAH) and 34 patients with post-hepatitis B liver cirrhosis (LC) were studied. RESULTS: The RTI was significantly lower in CAH and LC cases than in normal controls (P < 0.01). There was no difference between CAH and LC. The RTI of decompensated LC was significantly lower than that of the compensated LC (P < 0.05), indicating that there was no correlation between RTI and the parameters of routine liver functions. CONCLUSION: It is suggested that the RTI based on redox theory is effective and accurate in predicting hepatic energy reserve.

Adult↗
PubMed1996

Characterizing the DNA binding modes of a topoisomerase I-poisoning terbenzimidazole: evidence for both intercalative and minor groove binding properties.

We have used a broad range of spectroscopic and viscometric techniques to demonstrate that the complexation of a cytotoxic, topoisomerase I-poisoning terbenzimidazole (5PTB) with the poly(dA).poly(dT) duplex exhibits properties characteristic of both intercalation and minor groove binding. Our results reveal the following features: (i) Optical melting profiles reveal that 5PTB binding enhances the thermal stability of the poly(dA).poly(dT) duplex; (ii) Fluorescence-detected 5PTB binding to the poly(dA).poly(dT) duplex reveals four apparent "site sizes," ranging from 1 to 13 base pairs (bp) per bound drug; (iii) Flow linear dichroism data suggest conformational heterogeneity among the poly(dA).poly(dT)-bound 5PTB molecules, with substantial contributions from drug molecules bound in the minor groove; (iv) Fluorescence resonance energy transfer data reveal properties characteristic of a significant contribution from an intercalative mode of binding; (v) Viscometric, fluorescence quenching, and netropsin competition data are consistent with 5PTB binding to poly(dA).poly(dT) by "mixed" modes, which are operationally defined as single or multiple binding populations that individually and/or collectively express both intercalative and minor groove binding properties. We comment on a potential correlation between drugs that exhibit such "mixed" mode binding motifs and those that express antineoplastic activity through inhibition of topoisomerase I.

Benzimidazoles↗
PubMed1996

Agrobacterium tumefaciens mediated transformation of Orychophragmus violaceus cotyledon and regeneration of transgenic plants.

Excised cotyledons of Orychophragmus violaceus were used as explants for tissue culture. They were cultured on the MS medium supplemented with BA (3 mg/L) and NAA (0.2 mg/L). When the regenerated buds were 2 cm long, they were excised and transferred onto 1/2 MS medium with IBA (0.03 mg/L), then the whole plants were regenerated. The frequency of plant regeneration was 100%. Subsequently, the genetic transformation of O. violaceus was studied. After 2-3 days of cocultivation with Agrobacterium tumefaciens strain A208se (pTiT37, pROA93), the cotyledons were transferred onto the selection medium containing 25 mg/L Km and 250 mg/L Ap. After shoots emerged, they were excised and transferred onto the rooting medium containing 25 mg/L Km and 100 mg/L Cef. The roots were formed within 4-5 weeks. The whole plants were transplanted into pots and grew well. The frequency of plant regeneration was about 51%. The regenerated plants showed high enzymatic activities of beta-glucuronidase and neomycine phosphotransferase II. Southern blot analysis confirmed that NPTII gene had been stably integrated into the chromosomal genome of O. violaceus. The transformation frequency was 5.6%. The first transgenic plant of O. violaceus is being reported.

Agrobacterium tumefaciens↗
PubMed1996

Gene targeting of CFTR DNA in CF epithelial cells.

A goal of cystic fibrosis (CF) gene therapy is correction of the mutant CF transmembrane conductance regulator (CFTR) gene with wild-type (wt) DNA sequences to restore normal CFTR protein and function. Experiments with wtCFTR cDNA expression vectors have shown that the Cl ion transport phenotype associated with CF can be corrected to resemble that in normal cells. An alternative to cDNA-based gene therapy strategies is one that corrects endogenous mutant sequences by targeted replacement with the wt homologue. To test whether such a strategy was feasible, a small fragment homologous replacement (SFHR) strategy was used to replace specific genomic sequences in human epithelial cells. Small fragments of genomic wtCFTR DNA were transfected into transformed CF epithelial cells. Replacement by exogenous CFTR DNA at the appropriate genomic locus and its expression as mRNA was indicated by: (1) allele-specific polymerase chain reaction (PCR) amplification of genomic DNA and mRNA-derived cDNA; and (2) hybridization of PCR products with allele-specific probes. In addition, the functional activity of CFTR protein was determined by whole cell patch clamp. Southern hybridization and patch clamp analyses suggested that approximately 1 in 100 CF cells underwent a homologous replacement event that resulted in intact Cl transport.

Cell Line↗
PubMed1996

Episomal expression of wild-type CFTR corrects cAMP-dependent chloride transport in respiratory epithelial cells.

The isolation of the gene responsible for the Cl- ion transport defect in cystic fibrosis (CF) has provided important information about the relationship between the disease pathology and the underlying genetic and biochemical mechanisms. In addition, new areas of investigation and therapy are now possible. Most notably, the isolation of the CF gene, the cystic fibrosis transmembrane conductance regulator (CFTR) has been led to the development of different gene therapy strategies. To circumvent possible complications due to insertional mutagenesis and virally induced immune responses, we have employed Epstein-Barr virus (EBV)-based expression vectors for correction of the cAMP-dependent Cl- transport defect associated with CF. A CFTR-containing expression construct under the regulation of the Rous sarcoma virus (RSV) long terminal repeat (LTR) (pREP5/CFTR) was introduced into transformed human airway epithelial cells defective in cAMP-dependent Cl-transport. Transfected cells were assayed for Cl- ion transport by (36)Cl- efflux, SPQ, and patch clamp and showed restoration of intact cAMP-dependent transport. CFTR transcription from pREP5/CFTR was detected by Northern hybridization. The level of response to agonists appeared to be dependent on the level of CFTR expression. When cells were tested for functional expression of CFTR after removal of selection pressure, they showed a continuous decrease in responsiveness to forskolin as a function of time after removal of selection. This decrease correlated with a loss of CFTR mRNA in the loss of the PREP5/CFTR. After 12 to 15 weeks growth without selection both cAMP-dependent Cl- transport and plasmid-derived CFTR mRNA were not detectable. However, it was still possible to rescue cAMP-dependent Cl- transport in these transfected cells by reselection suggesting the presence of the CFTR containing plasmid in a portion of the cells. Analysis of DNA indicated that the pREP5/CFTR vector copy number was reduced from 30 copies per cell with continuous selection, to approximately 0.3 copies per cell after 20 weeks without hygromycin B.

Cells, Cultured↗
PubMed1996

[Lung carcinosarcoma--a report of 15 cases].

Lung carcinosarcoma is a rare pulmonary mixed malignant tumor. From November 1979 to Sept. 1992, among 4251 cases of pulmonary malignant tumor operated in our department 15 were lung carcinosarcoma (0.35%). Pneumonectomy was done in 6 patients, lobectomy in 8, thoacotomy in 1. Pathologically, squamous carcinoma with fibrosarcoma was observed in 4, squamous carcinoma with chondrosarcoma in 1, squamous carcinoma with pleomorphic sarcoma in 1, adenocarcinomma with fibrosarcoma in 7, adenocarcinoma with chondrosarcoma in 1, and small-cell carcinoma with chondrosarcoma in 1. There was no operation death. Upon follow up, the 1-, 3-, 5-, and 7-year survival rates were 66.7%, 53.3%, 42.9% and 2/7, respectively. The longest survival was 97 months. The histologica origin, the relationship between pathological findings and clinical features and the diagnosis, treatment and prognosis are discussed.

Adult↗
PubMed1996

Presence of free radicals in pigment gallstone in vivo.

OBJECTIVE: To clarify whether free radical, which may play a role in pigment gallstone formation, is present in pigment gallstones in vivo. MATERIALS AND METHODS: Free radical signal of gallstones from 18 patients was detected by electron paramagnetic resonance spectroscopy at 77K under anaerobic condition and in air (control). As soon as the anaerobic determination was finished, the fresh anaerobic sample was exposed to air and stored in a freezer at -20 degrees C. RESULTS: Free radical signal (g = 2.0038) was detected in fresh anaerobic samples containing more than 2% bilirubin compound, and the signal intensity correlated linearly with the content of calcium bilirubinate (r = +0.95, P < 0.0005). During the storage at -20 degrees C and exposure to air, the signal intensity of each anaerobic sample and its control increased gradually, eventually reaching the same stable level. Fe(III) signal intensity was enhanced synchronously and related linearly with free radical signal (r = +0.99, P < 0.0005). CONCLUSIONS: Free radical exists originally in pigment gallstones in vivo, and it may play an important role in pigment gallstone formation. The free radical signal carried by gallstones may be strengthened by the action of oxygen in air on bilirubin. The transition metal ions probably take part in the formation of bilirubin free radical.

Bilirubin↗
PubMed1996

The role of human leukocyte antigen in susceptibility and clinical manifestations of sarcoidosis.

OBJECTIVE: To investigate the correlation of human leukocyte antigen (HLA) with susceptibility and clinical manifestations of sarcoidosis. MATERIAL AND METHODS: Fifty-five patients with sarcoidosis and one hundred and six normal subjects were investigated. Genomic DNAs were purified using the proteinase K-phenol extraction method. DNA samples were amplified by the polymerase chain reaction (PCR) procedure using the DRB1 group specific primer pairs. RESULTS: The gene frequency of HLA-DR5 increased significantly in patients with sarcoidosis (P < 0.01), and HLA-DR7 decreased (P < 0.05). Gene frequencies of HLA-DR9 and HLA-DR5 increased remarkably in male patients and in patients with stage I and stage IIa, respectively (both P < 0.05). CONCLUSIONS: It is suggested that HLA-DR gene might contribute to the susceptibility as well as various clinical manifestations of sarcoidosis.

Adult↗
PubMed1996

Disaster-readiness of medical facilities in Aichi Prefecture.

One month following the Great Hanshin Earthquake of January 17, 1995, we conducted a survey of 173 hospitals in Aichi Prefecture to pinpoint problems related to their actual disaster-readiness and the medical backup systems in place to deal with such disasters. This study revealed that staff at 50% of the surveyed hospitals could reach the hospital within an hour, but that communication is almost entirely dependent on phone lines, suggesting that cordless/portable/mobile phones, radio systems, Internet, communications satellites and the like should be studied in the days to come for possible use as effective communication alternatives in times of disaster. Whereas 92% of the surveyed hospitals had manuals dealing with fire outbreaks, other areas were less well represented. For example, only 36.9% of surveyed hospitals had manuals for earthquakes, 31.7% had manuals for power outages and 14.2% had manuals to deal with flooding and water disasters. New manuals must be developed incorporating the key points garnered from experience (especially Hanshin) and be ready for use immediately. It is the time for each hospital to seriously rethink the measures it should take to deal with disasters.

Communication↗
PubMed1996

[Microsurgical anatomical study of the wall of the cavernous sinus].

OBJECTIVE: To observe the microanatomical structures of the wall of cavernous sinus (CS) in order to provide anatomical basis for direct microsurgical operation to the CS. METHODS: 48 aides of the CS of adult cadavers were dissected in detail under operative microscope. RESULTS: The CS was a narrow and long irregular hexahedron in shape. The supperior wall, the posterior wall and the superficial dural layer of the lateral wall of the CS were formed by internal layer of the cerebral dura. The deep layer of the interal wall was formed by the sheaths of nerves II, IV, V1, V2 with a reticular membrane between these sheaths. There was a superficial compartment between the superficial layer and deep layer of the lateral wall in 31.25% of the specimens. The inferior wall of the CS was intracranial periosteum. The medial wall was formed by stretched fibres from the tentorium of hypophysis. The anterior aspect was formed by the sphenoid sinus and the superior orbital fissure. Direct microsurgical approaches to the CS via the medial trangles of the superior wall and Parkinson tranales of the lateral wall were most important. CONCLUSION: A microanatomical structure of the wall of the CS is provided for direct microsurgical operation to the CS, and the direct microsurgical approaches are discussed.

Adult↗
PubMed1996

[Development of genetically engineered chimeric and single chain antibodies against human brain glioma: a preliminary report].

In order to improve the clinical usefulness of mAb of mouse origin in targeting diagnosis and therapy for human brain glioma, it is necessary to humanize it and reduce its molecular size. By means of RT-PCR technique, a 348 bp heavy chain variable domain (VH), and a 318 bp light chain variable domains (VL) cDNA fragments were cloned from mouse hybridoma cell line SZ39 secreting mAb against human brain glioma. By recombinant DNA technique, the two cDNA fragments were linked to human IgG1 heavy chain CH1 and light chain kappa constant regions, respectively, to form a chimeric gene which was then inserted into an expression vector pHEN1-SZ39 Fab/Hu. In addition, the two cDNA fragments were connected directly with a universal linker and inserted to an expression vector pHEN1-SZ39 ScFv. The two expression vectors were separately introduced into E. coli HB2151 to secrete chimeric antibodies and single-clain antibodies, respectively. On ELISA and Western blot, the two genetically engineered antibodies bond to the same 180,000 cell surface membrane antigen on human brain glioma cell line SHG44 as did the parental mAb SZ39.

Amino Acid Sequence↗
PubMed1996

[Alterations of plasma beta-EP and cortisol contents in thyroidectomy under acupuncture anesthesia and acupuncture anesthesia combined with tetrahydropalmatine].

Acupuncture anesthesia sometimes fails to give sufficient analgesia which may be overcome by appropriate combination of non-narcotic analgetics. We measured beta-endorphin (beta-EP) and cortisol contents in thyroidectomy under acupuncture analgesia (12 cases) and acupuncture anesthesia combined with tetrahydropalmatine (12 cases) by RIA. The results showed that the increase of beta-EP and cortisol in the latter group was less than that of the former, which proved that terahydropalmatine exerted a potentiating effect on acupuncture analgesia.

Acupuncture Analgesia↗
PubMed1996

Detection of Borrelia burgdorferi DNA in granulomatous tissues from patients with sarcoidosis using polymerase chain reaction in situ technique.

To investigate the correlation between sarcoidosis and Borrelia burgdorferi (Bb) infection, flagella DNA of Bb were detected in 23 granulomatous tissue specimens from patients with confirmed sarcoidosis using polymerase chain reaction in situ technique (in situ PCR) and the antibodies to Bb were examined in 55 serum samples obtained from the patients by indirect immunoflurescence assays. Our data presented that: (1) None of granulomatous tissues was found to have Bb DNA in 23 tissue samples. (2) Thirty of 55 (54.6%) patients with sarcoidosis were found antibodies to Bb positive, in contrast, six of 60 (10%) normal subjects had antibodies against Bb, the positive rate was remarkably higher in patient group than that in healthy group (P < 0.005). The results suggest that Bb might not be the causative agent of sarcoidosis, the elevated titres of serum antibodies against Bb in patients with sarcoidosis is a nonspecific response.

Antibodies, Bacterial↗
PubMed1996

[Correction of acquired ptosis using multilevel full-thickness eyelid resection].

The method of multilevel full-thickness eyelid resection combined with plication of the levator aponeurosis Müller's muscle was used to correct severe acquired ptosis. The 19 eyes of 13 patients treated with this method included neurogenic ptosis (3 eyes of 3 cases), myasthenia gravis ptosis (8 eyes of 4 cases), chronic progressive external ophthalmoplegia (4 eyes of 2 cases) and traumatic ptosis (4 eyes of 4 cases). All the patients had poor levator function. After operation their eyelids were elevated to an acceptable functional level without exposure keratopathy. The operative results were satisfactory. The operation procedure and indications were discussed.

Adult↗