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Biomedical subjects

Liang Chen

Publications and source records attributed to Liang Chen.

At least 127 records · Page 7Linked to original sources
PubMed2003

Diagnosis and surgical treatment of cavernous sinus hemangiomas: an experience of 20 cases.

OBJECTIVE: To elucidate the advances of diagnosis and surgical treatment of the cavernous sinus hemangiomas (CSHs). METHODS: The data from 20 patients with the CSHs surgically treated by authors from 1996 through 2000 was analyzed retrospectively, and a review of relevant literature was conducted. RESULTS: These 20 cases accounted for 16.3% of all intracranial cavernous hemangiomas surgically treated in the same period at Huashan Hospital. The patients were aged from 32 approximately 69 years with an average age of 47 years. There were 17 females and 3 males. The common clinical manifestations were visual loss, diplopia, headache, facial numbness and extraocular muscle palsy. Computed tomography (CT) and magnetic resonance imaging (MRI) were major preoperative diagnostic modalities, but demonstrated nonspecific features. The preoperative misdiagnostic rate was 38.9%. Of the 20 patients undergoing craniotomy via modified pterional approach with or without orbitozygomatic osteotomy, tumors were removed through epidural approach (EDA) in 13 cases, intradural approach (IDA) in 7 cases. Hypotension was induced during the operation in 2 cases. Total tumor removal was achieved in 12 cases (92.3%) in the EDA group and nil in the IDA group. Incomplete tumor removal was 1 case (7.7%) in the EDA group and 7 cases (100%) in the IDA group. One patient in the IDA group died of intracranial hemorrhage postoperatively. Compared with preoperative manifestations, cranial neuropathies at discharge were worsened in 76.9% of patients in the EDA group and 83.3% of patients in the IDA group, improved in 15.4% of patients in the EDA group and 16.7% of patients in the IDA group, unchanged in 7.7% of patients in the EDA group. Follow-up study (range, 1 approximately 6 years; mean, 3 years) was available in 17 patients (89%). All patients in the EDA group improved without tumor recurrence. Nonimprovement (2 cases) and continued worsening (3 cases) occurred in the IDA group. In patients with tumor incompletely removed, the tumor enlarged in 2 cases, and unchanged or decreased in size in 3 cases, in which 2 cases underwent postoperative radiosurgery or radiotherapy. According to pathologic and MRI characteristics, the CSHs can be divided into two types, sponge-like type and mulberry-like type. CONCLUSION: Cavernous hemangioma should be included in differential diagnosis for middle aged females with cavernous sinus tumors. Two types of the CSHs, sponge-like type and mulberry-like type, can be identified. The best microsurgical approach for the removal of the CSHs is epidural approach via the skull-base craniotomy. Radiosurgery should be considered for patients with incomplete tumor removal.

Adult↗
PubMed2003

Human gamma/delta T-cell proliferation and IFN-gamma production induced by hexamethylene diisocyanate.

BACKGROUND: The human immune response to isocyanate, a leading cause of occupational asthma, remains incompletely characterized, including the cell types involved and the form of the chemical that acts as an antigen. OBJECTIVE: The purpose of this investigation was to characterize human T cells that respond to hexamethylene diisocyanate (HDI), an aliphatic isocyanate routinely used in the automobile body industry. METHODS: Human T-cell lines were generated and characterized from peripheral blood of HDI-exposed and HDI-unexposed subjects, using two different HDI antigens, HDI-conjugated albumin and HDI-exposed human airway epithelial cells (NCI-H292). Flow cytometry was used to characterize the phenotype of HDI-responsive T cells. ELISA and intracellular staining techniques were used to evaluate HDI-induced cytokine production. DNA sequence analysis of T-cell receptors was used to further define clonal populations of HDI-responsive T cells. RESULTS: HDI antigen preparations but not "mock exposed" control antigens lead to increased proliferation of specific cell types, CD3+CD4-CD8(dim) and/or CD3+CD4-CD8- cells, from HDI-exposed but not from HDI-unexposed subjects. These HDI-responsive T cells expressed unique oligoclonal gamma/delta rather than alpha/beta T-cell receptors, with characteristics suggestive of antigen-mediated selection and specificity. The HDI-stimulated gamma/delta T cells were associated with T(H)1-like cytokines and produce IFN-gamma but not IL-5 or IL-13. CONCLUSIONS: These data are the first to demonstrate that HDI can selectively stimulate gamma/delta T cells with the potential to modulate the human immune response to exposure.

Allergens↗
PubMed2003

Alteration of DNA adenine methylase (Dam) activity in Pasteurella multocida causes increased spontaneous mutation frequency and attenuation in mice.

Pasteurella multocida is one of the primary bacterial pathogens associated with bovine respiratory disease (BRD) complex. Relatively few virulence factors of P. multocida have been characterized, and there is a need for improved vaccines for prevention of BRD. In other Gram-negative species, DNA adenine methylase (Dam) regulates the expression of virulence genes, and appropriate expression of Dam is required for virulence. In this study, the authors cloned and sequenced the P. multocida A1 dam gene and demonstrated that it is able to restore Dam function in an Escherichia coli dam mutant. When P. multocida dam was placed under the control of a constitutively expressed promoter on a plasmid, it caused an increased spontaneous mutation rate in P. multocida. In addition, the plasmid-mediated alteration of Dam production in P. multocida caused it to be highly attenuated in mice. These findings indicate that appropriate expression of Dam is required for virulence of P. multocida, which is believed to be the first report that Dam is required for virulence of a species in the Pasteurellaceae. Therefore, Dam may function as a virulence gene regulator in the Pasteurellaceae, similar to previously reported findings from other Gram-negative species.

Animals↗
PubMed2003

DNA topoisomerase III from the hyperthermophilic archaeon Sulfolobus solfataricus with specific DNA cleavage activity.

We report the production, purification, and characterization of a type IA DNA topoisomerase, previously designated topoisomerase I, from the hyperthermophilic archaeon Sulfolobus solfataricus. The protein was capable of relaxing negatively supercoiled DNA at 75 degrees C in the presence of Mg2+. Mutation of the putative active site Tyr318 to Phe318 led to the inactivation of the protein. The S. solfataricus enzyme cleaved oligonucleotides in a sequence-specific fashion. The cleavage occurred only in the presence of a divalent cation, preferably Mg2+. The cofactor requirement of the enzyme was partially satisfied by Cu2+, Co2+, Mn2+, Ca2+, or Ni2+. It appears that the enzyme is active with a broader spectrum of metal cofactors in DNA cleavage than in DNA relaxation (Mg2+ and Ca2+). The enzyme-catalyzed oligonucleotide cleavage required at least 7 bases upstream and 2 bases downstream of the cleavage site. Analysis of cleavage by the S. solfataricus enzyme on a set of oligonucleotides revealed a consensus cleavage sequence of the enzyme: 5'-G(A/T)CA(T)AG(T)G(A)X / XX-3'. This sequence bears more resemblance to the preferred cleavage sites of topoisomerases III than to those of topoisomerases I. Based on these data and sequence analysis, we designate the enzyme S. solfataricus topoisomerase III.

Archaeal Proteins↗
PubMed2003

[Clinical investigation on characteristics of traditional Chinese medical syndrome of hepatocirrhosis].

OBJECTIVE: To explore the characteristics of traditional Chinese medical syndrome (TCM syndrome) of hepatocirrhosis. METHODS: Clinical information from the four diagnosis methods of traditional Chinese medicine (TCM) and related laboratorial indexes were systematically collected from 223 hepatocirrhosis cases, and the multi-statistical methods including systematic cluster analysis, principal component analysis, stepwise discrimination and variance analysis were made with the software SAS 6.11. RESULTS: Multi-analysis showed that there were 3 categories of syndrome characteristics. Type 1 (134 cases): damp heat, blood stasis, deficiency of liver and spleen Qi; Type 2 (62 cases): deficiency of both Qi and Yin with severe deficiency of Qi, heat with severe dampness, blood stasis; Type 3 (27 cases): deficiency of both Qi and Yin with severe deficiency of Yin, stasis and heat or dampness. Analysis of the changes of the related laboratorial indexes among the three types of syndrome showed that Type 1 mainly manifested asthenia syndrome with sthenia syndrome, and its indexes of AST, ALT, GGT levels were markedly higher than those of Type 2 and Type 3, both of which mainly showed sthenia syndrome with asthenia syndrome, and that Type 3 was in active inflammation, deficiency of both Qi and Yin (deficiency of Yin > deficiency of Qi), and its FN, Alb, FV, FVII, PLT, PCT levels were obviously reduced. CONCLUSION: The multi-statistical methods can reveal the characteristics and regularity of TCM syndrome of hepatocirrhosis, and the 3 categories of syndrome characteristics basically conform to clinical manifestations. The result of TCM syndrome distribution and laboratorial indexes infer that damp heat is the pathological basis of hepatocirrhosis, and the degree of liver function disorder and liver damage may be the pathological basis of deficiency of Yin of both liver and kidney.

Adult↗
PubMed2003

Complications associated with posterior lumbar interbody fusion using Bagby and Kuslich method for treatment of spondylolisthesis.

OBJECTIVE: To analyze complications associated with posterior lumbar interbody fusion (PLIF) in which two Bagby and Kuslich (BAK) interbody fusion cages were implanted. METHODS: A total of 118 patients with spondylolytic spondylolisthesis underwent single-level PLIF using two BAK cages filled with morselized autogenous bone. The major clinical and radiographic complications were analyzed after a follow-up with an average time of 2 years and 9 months. RESULTS: Complications were divided into intraoperative and postoperative complications. Intraoperative complications mainly included dural tear (4 patients, 3.4%), nerve root injury (3 patients, 2.5%) and suboptimal cage position (9 patients, 7.5%). No death was caused by the operation. Postoperative complications chiefly consisted of cage retropulsion (3 patients, 2.5%), cage subsidence (4 patients, 3.4%), and postlaminectomy arachnoiditis (2 patients, 1.7%). Pseudarthrosis was noted radiographically with evidence of motion between adjacent vertebra on lateral flexion-extension films and luciencies around the cages (2 patient, 1.7%), continuous posterior cage migration (2 patients, 1.7%) or continuous cage subsidence (2 patients, 1.7%). Two patients died, one from a traffic accident and the other from metastatic cancer 1 year postoperatively. CONCLUSIONS: The results of this study indicate that PLIF with BAK cages is an effective but also technically difficult procedure. The relatively high incidence of complications reminds us of the importance of surgical indications and proper manipulations.

Adult↗
PubMed2003

[A powerful tool for study of sperm--soft X-ray microscopy].

Soft X-ray microscopy is a microimaging technique using soft X-ray as illuminative source. It fills the gap between optical and electron microscopy. Soft X-ray microscopes have better resolution than visible microscopes. In comparison with electron microscopes, it can examine thick (up to 10 micrometers for biological samples) and wet specimens in their natural states without being dehydrated, sectioned and stained. In addition, soft X-ray microscopy can map elements and analyze the biological macromolecules such as protein and DNA in the examined samples. In this paper, the advantages of soft X-ray microscopy for biology are briefly described. The applications of soft X-ray microscopy to the analysis of mammal and human sperm are illustrated.

Animals↗
PubMed2003

[Brain-derived neurotrophic factor mRNA expressions in rat brain induced by short-term in vivo exposure to deltamethrin].

OBJECTIVE: To elucidate the mechanism of damage on central nervous system (CNS) caused by deltamethrin (DM). METHODS: The mRNA and protein expressions of brain-derived neurotrophic factor (BDNF) in the cerebral cortex and hippocampus of the rats exposed to DM were measured by retro-transcription-polymerase chain reaction (RT-PCR), dot blot, flow cytometry analysis and immunohistochemistry. RESULTS: After exposure to DM at high-dose (DM1, 25.0 mg x kg(-1) x d(-1), i.p.) once and low-dose (DM2, 12.5 mg x kg(-1) x d(-1), i.p.) for 5 days, the level of BDNF mRNA and protein expression in the cerebral cortex and hippocampus of the rats increased significantly. The levels of BDNF mRNA and protein expression in the cerebral cortex and hippocampus measured by of RT-PCR in the rats with DM1 and DM2 were higher than those in the controls by 48% and 56%, and 59% and 54%, respectively. And, those measured by dot blot in the rats with MD1 and MD2 were 186% and 161%, and 148% and 158% of those in the controls, respectively, basically similar to those measured by RT-PCR. Flow cytometric analysis showed that the levels of BDNF mRNA and protein expression in the cerebral cortex and hippocampus in the rats with DM1 and DM2 were higher than those in the controls by 53% and 89%, and 45% and 46%, respectively. Immunohistochemical analysis showed that protein expression in the cerebral cortex of the rats with DM1 and DM2 were 129% and 147% of those in the controls, same as the flow cytometric analysis, but those were significantly higher in the hippocampus mainly in the CA1 and DG areas of the rats with MD1 and the CA3 and DG areas of the rats with DM2. CONCLUSIONS: DM could induce BDNF mRNA and protein expression in the cerebral cortex and hippocampus of the rats, which could play an important role in repairing of nerve damage.

Animals↗
PubMed2003

Molecular cloning and characterization of Stevia rebaudiana UDP-glucosyltransferase.

We report here the cloning and characterization of a UDP-glucose flavonoid glucosyltransferase (srUFGT) in Stevia rebaudiana. The isolated cDNA was 1419 bp in length encoding 473 deduced amino acids with a predicted molecular mass of 53.2 kDa. The products of in vitro translation from an expression vector had anthocyanidins and steviol glucosyltransferase activity. Comparison of the activity of the recombinant UDP-glucosyltransferase toward a range of acceptor substrates suggests that it may participate in the synthesis of steviol glycosides. The results support the hypothesis that the flavonoid glucosyltransferases, which have a broad substrate specificity, may be not only involved in flavonoid glucosylation but also play a role in producing the water-soluble steviol-glycosides in S. rebaudiana.

Amino Acid Sequence↗
PubMed2003

[A study on the clinical efficacy of a combination regimen with levofloxacin and capreomycin in the treatment of multi-drug resistant pulmonary tuberculosis].

OBJECTIVE: To study the clinical efficacy of a combination therapy with levofloxacin (LVFX), capreomycin (CPM) and other second-line antituberculosis drugs in the treatment of multi-drug resistant pulmonary tuberculosis (MDR-TB). METHODS: 177 patients with MDR-TB were assigned to a study group (88 cases), treated with LVFX, CPM, pyrazinamide (PZA), rifapentine (RFT) and pasiniazid (PSZ); or a control group, treated with streptomycin (SM), ethambutol (EMB), PZA, RFT and PSZ. The course of treatment was 21 months. RESULTS: 82 cases in the study group and 79 cases in the control group completed the treatment. The sputum negative conversion rate in the study group (83%) was significantly higher than that in the control group (58%) (P < 0.01). The radiographic improvement rate was 50% in the study group, significantly higher than that in the control group (28%) (P < 0.01). The closure rate of the lung cavities in the study group (63%) was higher than that in the control group (42%) (P < 0.05). No significant difference was found in side-effects between the two groups (31% in the study group, and 35% in the control group respectively) (P > 0.05). CONCLUSION: The regimen including LEVX, CPM and other second-line anti-TB drugs was effective and safe for patients with MDR-TB.

Adolescent↗
PubMed2003

Image-guided resection of cerebral cavernous malformations.

OBJECTIVE: To evaluate retrospectively the effectiveness of image-guided navigation techniques in the management of cerebral CMs. METHODS: Between July 1997 and January 2001, 44 patients underwent image-guided resection of cerebral CMs. To counteract brain shift, a small silicon catheter was implanted as a guide in the case of deep-seated lesions (except in the case of brain stem CMs) and before excision of multiple lesions. RESULTS: A total of 27 men and 17 women with a mean age of 35 years underwent surgical procedures (5 patients had multiple lesions). The lesions were located in the frontal (n = 14), lobe temporal lobe (n = 12), parietal lobe (n = 6), cerebellum (n = 6), thalamus (n = 5), pons (n = 5), and orbital region (n = 1). Under the guidance of a StealthStation navigator, total removal of the lesions was achieved in all patients. Follow-up revealed marked improvement of preoperative symptoms in 26 patients and no additional deficits in 13 patients. Five patients suffered from additional neurological deficits, but two of them gradually improved during the follow-up period. CONCLUSIONS: With the assistance of an image-guided surgical system, functional areas can be effectively avoided and surgical injury can be decreased. This system is well suited for accurate localization and safe resection of small, deep-seated CMs.

Adult↗
PubMed2003

[Supervision, administration and standard research related to tissue engineered medical products].

Tissue engineering advance in supplying the reparative and reconstructive medicine with promising tissue engineered medical products(TEMPs) and the new therapy alternative. The related supervision and administration of TEMPs is being developed and the standard research of TEMPs is also in progress. The Food and Drug Administration(FDA) of the United States has treated TEMPs as combined products and supervised them according to the level of risk to patients. Lately, FDA has determined that the Center for Devices and Radiological Health (CDRH) should take charge of examination and approval of TEMPs, with the cooperation of the Center for Biological Evaluations and Research(CBER). The regulatory controls have been established respectively in European Union and Japan. In China, TEMPs are identified as medical devices combined with cells. The Department of Medical Device of the State Food and Drug Administration (SFDA) is responsible for the examination and approval of TEMPs, and National Institute for the Control of Pharmaceutical & Biological Products(NICPBP) is responsible for evaluation tests. The standards of TEMPs are formulated mainly by the American Society of Testing Materials(ASTM) and International Standardization Organization(ISO).

Biological Products↗
PubMed2003

[Determination of platelet activating factor in middle ear effusion of patients with secretory oitits media].

OBJECTIVE: To study the role of platelet activating factor (PAF) in the pathogenesis of secretory otitis media (SOM). METHOD: The content of PAF in blood plasma and middle ear effusion(MEE) were measured in 56(68years) patients with secretory otitis media and in 40 normal subjects respectively by RP-HPLC. RESULT: The concentration of PAF in MEE was remarkably higher than those in blood plasma (P < 0.01). The concentration of PAF in blood plasma in the SOM group was higher than those in the normal control group(P < 0.05). The concentration of PAF of MEE in the mucous fluid group was higher than those in the serous fluid group(P < 0.01). CONCLUSION: PAF might be an important mediator in MEE of SOM, it might be closely related to the persistence of SOM, and might play an important role in the pathogenesis of SOM.

Adolescent↗
PubMed2003

[Effects of deltamethrin on cell survival rate and intracellular free Ca2+ concentration in primary cultured astrocytes of rat].

OBJECTIVE: To study the effects of deltamethrin (DM) on cell survival rate and intracellular Ca(2+) ([Ca(2+)]i) concentration in primary cultured astrocytes of rat. METHODS: The cell survival rate was measured by Typan Blue assay; the intracellular [Ca(2+)]i concentration was determined by the fluorescent Ca(2+) indicator Fura-2/AM. RESULTS: The survival rate of astrocytes was decreased to 91.9% after astrocytes were incubated with 1 x 10(-5) mol/L DM for 72 h (P < 0.05). The cell survival rates were 89.0%, 84.8%, 81.2% and 79.2% respectively when astrocytes were administered with 1 x 10(-4) mol/L DM for 4, 12, 24 and 72 h, which were remarkably lower than control groups (P < 0.01). Comparing with controls and before DM treatment, sharp increases in [Ca(2+)]i concentration [(451.4 +/- 42.3), (536.9 +/- 47.5) and (870.9 +/- 100.5) nmol/L respectively] were observed when astrocytes were incubated with 1 x 10(-7), 1 x 10(-6) and 1 x 10(-5) mol/L DM for 5 minutes (P < 0.01). After astrocytes were treated with 1 x 10(-8), 1 x 10(-7), 1 x 10(-6), 1 x 10(-5) mol/L DM for 15 minutes, the [Ca(2+)]i concentrations were decreased to (124.3 +/- 6.0), (131.3 +/- 19.1), (118.9 +/- 1.4), (136.6 +/- 3.8) nmol/L respectively, which were significantly different from those of controls and before treatment. And this situation was almost keeping stable to 30 min. CONCLUSION: The cell survival rate was decreased and the [Ca(2+)]i concentration was temporarily increased when astrocytes were treated with DM.

Animals↗
PubMed2002

Heterogeneous decomposition of CHF2OCH2CF3 and CHF2OCH2C2F5 over various standard aluminosilica clay minerals in air at 313 K.

The heterogeneous decomposition of CHF2OCH2C2F5, a potential substitute for hydrofluorocarbons, over aluminosilica clay minerals in air, was confirmed to occur at 313 K in a closed-circulation reactor. HC(O)OCH2C2F5, the gaseous main product was produced through hydrolytic elimination of F atoms from the CHF2OCH2- group. CHF2OCH2CF3 also decomposed to HC(O)OCH2CF3 over the clay minerals. The pseudo-first-order rate constants were determined for the decompositions over eight types of clay minerals (19 samples). The various clay minerals had different abilities to decompose these hydrofluoroethers. The decomposition rates per Brunauer-Emmett-Teller surface area and the conversion ratios to HC(O)OCH2C2F5 or HC(O)OCH2CF3 for the reactions over kaolinite, halloysite, and illite were high in comparison to those for the same reactions over montmorillonite, hectorite, and nontronite. The dependence of this heterogeneous reaction on temperature and relative humidity indicates that, in the environment, the reaction could be important only in hot, dry regions. The results did not suggest that sunlight would directly accelerate the decay of CHF2OCH2CF3 or CHF2OCH2C2F5. In the presence of clay-containing soils in arid areas, this hydrolytic oxidation reaction may significantly affect both the lifetime and the degradation products of CHF2OCH2CF3 and CHF2OCH2C2F5 in the troposphere.

Aluminum Silicates↗
PubMed2002

[Image-guided microsurgery in resection of intracranial cavernous hemangioma].

OBJECTIVE: To study the methods and effectiveness of image-guided microsurgery in resection of intracranial cavernous hemangioma. METHODS: Between July 1997 and January 2001, 44 patients with intracranial cavernous hemangioma, 27 males and 17 females with a mean age of 35 years, among which 5 cases had multiple lesions, underwent image-guided microsurgery. The locations of lesions included frontal lobe (n = 14), temporal lobe (n = 12), parietal lobe (n = 6), cerebellum (n = 6), thalamus (n = 5), pons (n = 5), and orbital lobe (n = 1). A small silicon catheter, used as a guider, was implanted to the deep-seated lesion (except the brain stem lesions) before excision of the lesion in order to prevent brain shift. RESULTS: Total removal of the lesions was achieved in all patients without operational death. Follow-up revealed marked improvement of symptoms in 26 case and no change of symptom(s) in 13 cases. 5 cases suffered from additional neurological deficits, mainly exacerbation of hemiparalysis and aphasia, the condition of two of which, however, gradually improved within the period of follow-up. No residue of lesion and relapse were found during follow up. CONCLUSION: With the assistance of the image-guided surgical system, functional area can be effectively avoided, and surgical injury can be decreased. It is well suited for accurate localization and safe resection of small, deep-seated cavernous malformations.

Adolescent↗
PubMed2002

The inhibition of lung cancer cell growth by intracellular immunization with LC-1 ScFv.

A monoclonal antibody, LC-1, recognizing lung cancer associated common antigens was obtained in authors' laboratory. Its single chain Fv fragment (ScFv) named LC-1 ScFv was constructed based on recombinant phage displayed techniques. For expression on cell membrane, LC-1 ScFv was cloned into pDisplay vector, which directed the cloned gene to express as cell membrane bound protein. The resulting plasmid was sequenced and then introduced by the lipofectin method into a lung adenocarcinoma cell line SPC-A-1. G418 resistant cells were obtained by G418 selection. After transfection, LC-1 ScFv expression was observed by Western blot analysis and the expression of cognate antigens was down-regulated as shown in ELISA assay. SPC-A-1-pDisplay-ScFv cells grew in vitro at lower speed than the control intact cells and the cells transfected with vacant vector. Flow cytometry analysis detected a substantial increase in G1 phase and decrease in S phase in population of SPC-A-1-pDisplay-ScFv cells compared to SPC-A-1 and SPC-A-1-pDisplay cells. Semi-quantitative RT-PCR analysis showed that c-myc expression was down-regulated in SPC-A-1-pDisplay-ScFv cells. It seems that the antigens recognized by LC-1 may be in some way involved in a growth stimulating pathway and the antibody blocking of the function of the antigens shut down the pathway and thus down-regulate the expression of c-myc and growth of the cells.

Adenocarcinoma↗