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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 271 records · Page 15Linked to original sources
PubMed2001

[The tissue engineering research on synovialization of non-synovial membrane tendon].

The synovial membrane tissue within the flexor digital tendon sheath of the rabbit's toes was cultured in vitro. The synovial cells suspension of the subculture was cultured with the segments of the non-synovial membrane tendon of the rabbit's toes. Under the light microscopy, scanning electronic microscopy and immunohistochemical examination, the result showed that the synovial cells crawled and covered the surface of the segments of the non-synovial membrane tendons. It is suggested that the non-synovial membrane tendon could transform into a synovial membrane tendon.

Animals↗
PubMed2001

[Expression of human brain derived neurotrophic factor gene in E. coli].

The primers specific for the full-length BDNF coding sequence was designed and synthesized. The BDNF coding sequence was directly amplified from human genomic DNA by using PCR and inserted into vector pGEM-3Zf(+). The recombinant DNA was transformed into the host cells JM109 to obtain the positive clone pGEMBF18. The restriction enzyme analysis and DNA sequence detection confirmed that the inserted fragment of clone pGEMBF18 is the full-length BDNF coding sequence. The hBDNF DNA fragment was recovered from the clone pGEMBF18 and ligated with prokaryotic expression vector pGEX-5T to construct the recombinant expression plasmid p5TBF34. The E. coli JM109 transformed with p5TBF34 was induced with IPTG. A new protein band with apparent molecular weight 43 kDa was detected in the lysate of the transformed cell by using SDS-PAGE. The result of western hybridization showed that this fusion protein reacted specifically to the antibodies to human BDNF. The amount of the soluble fusion protein was about 503.04 mg/L lysate, 7.53% of total bacterial soluble protein of transformed cells, estimated by absorbance scanning of SDS-PAGE and protein quantitation.

Brain-Derived Neurotrophic Factor↗
PubMed2001

[Intron 44 is not the most unstable intron in the "central deletion hot spot" of dystrophin gene].

OBJECTIVE: To understand the distributional characteristics of dystrophin gene deletion breakpoints in "central deletion hot spot" and analyze the instability of introns 44-51 after excluding the effect of intron's length. METHODS: Fifty-nine Duchenne/Becker muscular dystrophy(DMD/BMD) patients were detected by polymerase chain reactions with the primers to amplify exons 44-52 of dystrophin gene. The amount of actual breakpoints, expected breakpoints according to its length, and the ratios of actual breakpoints to expected values(A/E) for introns 44-51 were calculated respectively. RESULTS: In "central deletion hot spot", about 30.8% of breakpoints fell in intron 44, about 23.1%, 17.9%, 10.3%, 10.3% of breakpoints fell in introns 50,51, 45, 48, respectively. But the amount of actual breakpoints of intron 44 was less than that of expected breakpoints according to its length, the ratio of A/E was 0.7. The amount of actual breakpoints of introns 48, 50, 51, 45 were more than that of length expected value. The ratios of A/E were 2.7, 2.0, 1.9, 1.1, respectively. CONCLUSION: Intron 44 is more stable than the whole molecular region of "central deletion hot spot". Introns 48, 50 and 51 are comparatively instable in "central deletion hot spot".

Dystrophin↗
PubMed2001

[Rapid detection of the common alpha-thalassemia-2 determinants by PCR assay].

OBJECTIVE: Most frequent molecular lesions of alpha-thalassemia-2 determinants are deletions of one alpha-globin gene. Satisfactory PCR methodologies for detecting the deletions are required for molecular diagnosis and genetic screening since there was no internal control in most published PCR-based strategies. The purpose of this study is to develop a reliable PCR protocol specific for the two common alpha-thalassemia-2 determinants with internal control. METHODS: The multiple repeat elements and the high GC-content of the alpha-globin locus impose severe limitations on designing suitable primers and optimizing stable conditions for PCR. In this study, two multiplex PCR systems were successfully set up. One was designed to detect the rightward deletion (-alpha(3.7)/) with two pairs of primers including one newly optimized pair for amplification of the internal standard to indicate the success of failure of PCR amplification. The other, to the leftward deletion(-alpha(4.2)/) with three primers, which were designed according to the newly sequenced data of the -alpha(4.2) and HbQ-alpha(4.2) deletions in this lab(Genbank Accession No. AF221717). In the PCR system, one is used as a common upstream primer and the other two are used as specific downstream primers for typing the normal allele and the deletion one, respectively. RESULTS: Easily interpretable, unambiguous amplifications were observed by using the multiplex PCR systems for the detection of the two common alpha-thalassemia-2 determinants. The three or four primers were run in the same tube under the same condition and both of these two systems could be used at the same thermal cycle parameters. For typing the rightward deletion, a mutant-specific amplification of 1.7 kb and a 1140 bp amplified band as a normal and system control were produced. For typing the leftward deletion, two PCR-amplified bands, a 956 bp fragment specific for a -alpha(4.2) gene and a 1140 bp one for a normal allele were found. CONCLUSION: Two sets of PCR systems with internal controls for detecting the most common two alpha-thalassemia-2 determinants have been established and may be suitable for molecular diagnosis and population screening.

Base Sequence↗
PubMed2001

[Primary discussion on the imported materia medica].

The features, with respect to medical use, dosage form, manufacture technology and quality, of licensed imported materia medica and botanical preparation in market were discussed in this paper. The international market competition of Chinese Materia Medica was analyzed, and the countermeasure to resist the imported materia medica was also included.

Drugs, Chinese Herbal↗
PubMed2001

[Genetic polymorphisms of cytochrome P450 1A1 and susceptibility of early-onset Parkinson's disease].

OBJECTIVE: To assess the possible association between the Msp I polymorphisms of cytochrome P450 1A1(CYP1A1) and the susceptibility of early-onset Parkinson's disease among Hans in the northern part of China. METHODS: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to analyze three genotypes A, B and C in 3'flanking region of CYP1A1 in 126 patients with idiopathic early-onset Parkinson's disease and 172 healthy controls. RESULTS: The frequencies of genotypes A, B and C in patients were 41.3%, 43.6% and 15.1% while those in the controls were 34.9%, 51.7% and 13.4%, respectively. No statistically significant difference in the frequencies of the three genotypes was observed between the two groups. The frequencies of two alleles were of no significant difference between the patients and controls. CONCLUSION: The above results suggest that the Msp I polymorphisms of cytochrome P450 1A1 itself might not be associated with idiopathic early-onset Parkinson's disease.

Adult↗
PubMed2001

Pro- and anti-inflammatory forms of interleukin-1 in the tear fluid and conjunctiva of patients with dry-eye disease.

PURPOSE: To compare the expression of the pro- and anti-inflammatory forms of interleukin (IL)-1 in the tear fluid and conjunctival epithelium of normal eyes and those with dry-eye disease. METHODS: The concentrations of IL-1 alpha, IL-1 beta (precursor and mature forms), and IL-1 receptor antagonist (IL-1Ra) were measured by ELISA in tear fluid samples obtained from normal individuals and patients with dry eye who had rosacea-associated meibomian gland disease (MGD) or Sjögren's syndrome (SS) aqueous tear deficiency (ATD). These cytokines were also measured in normal tear fluid before and after nasal stimulation to induce reflex tearing. The relative expression of these cytokines was evaluated in conjunctival impression cytology specimens and conjunctival biopsy tissue obtained from normal subjects and SS ATD-affected patients using immunofluorescent staining. Matrix metalloproteinase (MMP)-9 concentration and activity in the tear fluid were evaluated with gelatin zymography and with an MMP-9 activity assay kit, respectively. RESULTS: Compared with normal subjects, the concentration of IL-1 alpha and mature IL-1 beta in the tear fluid was increased, and the concentration of precursor IL-1 beta was decreased in patients with MGD (P < 0.05, P = 0.02, and P < 0.01, respectively) and SS ATD (P < 0.001, P = 0.02, and P < 0.001, respectively). There was no significant change in the concentration of IL-1 alpha, precursor IL-1 beta, and IL-1Ra in reflex tear fluid, indicating that the lacrimal glands may secrete these cytokines. The activity of MMP-9, a physiological activator of IL-1 beta, was significantly elevated in the tear fluid of both dry-eye groups compared with normal subjects. A strong positive correlation was observed between the intensity of corneal fluorescein staining and the tear fluid IL-1 alpha concentration (r(2) = 0.17, P < 0.02) and the mature-to-precursor IL-1 beta ratio (r(2) = 0.46, P < 0.001). Positive immunofluorescent staining for IL-1 alpha, mature IL-1 beta, and IL-1Ra was observed in a significantly greater percentage of conjunctival cytology specimens from eyes with SS ATD than in those from normal eyes (P < 0.01 for IL-1 alpha, P < 0.009 for mature IL-1 beta, and P < 0.05 for IL-1Ra). CONCLUSIONS: Dry-eye disease is accompanied by an increase in the proinflammatory forms of IL-1 (IL-1 alpha and mature IL-1 beta) and a decrease in the biologically inactive precursor IL-1 beta in tear fluid. Increased protease activity on the ocular surface may be one mechanism by which precursor IL-1 beta is cleaved to the mature, biologically active form. The conjunctival epithelium appears to be one source of the increased concentration of IL-1 in the tear fluid of patients with dry-eye disease. These results suggest that IL-1 may play a key role in the pathogenesis of keratoconjunctivitis sicca.

Adult↗
PubMed2001

Behavioral characterization of dopamine D5 receptor null mutant mice.

To study behavioral functions of the D5 subtype, mice were generated with null mutations in the D5 gene. This 1st behavioral characterization of D5 null mutant mice (D5-/-) indicated normal general health, sensory abilities, and neurological reflexes. Under basal conditions, D5-/- mice were generally normal on locomotor activity, the rotarod test, acoustic startle response, prepulse inhibition, elevated plus-maze, light <--> dark exploration, Morris water maze, and cued and contextual fear conditioning. In the Porsolt forced swim test for antidepressant activity, male D5-/- mice showed lower levels of immobility. D5-/- mice showed some evidence of reduced responses to the hyperactivity-inducing effects of the D1/D5 receptor agonist SKF 81297. The ability of SKF 81297 to disrupt acoustic startle and prepulse inhibition appeared to be attenuated in D5-/- mice. These results suggest that the D5 receptor is not essential for many dopamine-mediated behaviors but may contribute to the pharmacological activation of dopaminergic pathways relevant to exploratory locomotion, startle, and prepulse inhibition.

Animals↗
PubMed2001

[Genetic variation of the core and E1 region of hepatitis C virus in serum collected from patients with chronic hepatitis].

OBJECTIVE: To study the association of the core and E1 region variation of hepatitis C virus (HCV) with the chronicity of HCV infection. METHODS: Acute-phase plasma samples from two drug-injection users who acquired HCV infection during six-month follow-up and ten patients with chronic hepatitis C were obtained. A 1-kb fragment containing the 3' half of core, completed E2 and 3' half of E2 were amplified by nested reverse transcription polymerase chain reaction (RT-PCR). For each 30 cloned cDNAs were examined by a method that combined heteroduplex (HD) analysis and a single-stranded conformational polymorphism (SSCP) assay to assess quasispecies complexity and optimize selection of clones with unique gel shift patterns for sequenceing. Amino acid sequences were analyzed for signature patterns and glycosylation signals. RESULTS: There was obvious difference between the SSCP bands of cloned cDNAs representing core-E1 region, but not obvious distance between heteroduplexes and the homoduplex. There was no change in the sequence of each clonotype from acutely HCV-infected subjects, whereas the rate of nonsynonymous substitution was 1.32% in amino acid sequence of E1 from persistently HCV-infected subjects with except for functional patterns. CONCLUSIONS: The variation of the E1 gene of HCV is in the presence of quasispecies population but might not related with its immunologic escape.

Chronic Disease↗
PubMed2001

Transition state spectroscopy of the I + HI reaction in clusters: photoelectron spectroscopy of IHI-.Arn (n = 1-15).

We have investigated effects of solvation on the transition state spectroscopy and dynamics of the I + HI reaction by measuring the anion photoelectron (PE) spectra of the clusters IHI-.Arn (n = 1-5). Argon clustering results in a successive shift of the PE spectra to lower electron kinetic energies with increasing cluster size. It also leads to significant vibrational cooling in the PE spectra and facilitates the observation of features associated with symmetric stretch vibrations and hindered rotational motions of the transition state complex IHI. The shifts in electron binding energy suggest that the first six argon atoms form a ring around the waist of the IHI- anion, just as in I2-.Arn. The spacing of the antisymmetric stretch features evolves with cluster size and is attributed at least in part to perturbation of the IHI- geometry in larger argon clusters. Intensities of features due to hindered rotation are enhanced for larger clusters, possibly due to solvent perturbation of the neutral transition state region.

Journal Article↗
PubMed2001

[Automatic analysis and research on the trend of ST-T segment based on KL transform].

In view of the limitation of monitoring the trend of ST segment with the traditional method(ST level), we introduce a new monitor method based on KL transform. This method has overcome many disadvantages of ST level, e.g. the susceptibility to interference, a large variation of performance and the reflection of isolated characteristic. This method can characterize the signals stably and adequately. We have made experiment and analyzed the property of this method by using the standard database. The results indicate that the KL transform is of great clinical significance in detecting and monitoring the abnormality of the ST-T segment waveform over a long period of time, and the effect of monitor is also laid on the selection of KL series.

Electrocardiography↗
PubMed2001

[Ectopic expression of human brain derived neurotrophic factor gene in fibroblasts].

The full-length sequence encoding hBDNF was inserted down into the enhancer-promotor regulatory element of Colia1 to construct minigene Colia1-BDNF. The recombinant eukaryotic expression plasmid pSCEPBFCAT was transfected into human fetal tendon fibroblasts in culture to realize ectopic expression of hBDNF gene in fibroblasts. The results of immuno-dot blot, Elisa and Western hybridization confirm that the expression protein with apparent molecular weight 27 kDa in pSCEPBFCAT transfected fibroblasts possesses antigen activity specific for the antibodies to BDNF.

Brain-Derived Neurotrophic Factor↗
PubMed2001

Large strain behaviour of brain tissue in shear: some experimental data and differential constitutive model.

In this paper, some experimental measurements of the behaviour of bovine brain tissue under large shear strains in vitro are reported, and a constitutive model which is consistent with the data is developed. It was determined that brain tissue is not strain-time separable, showing slower relaxation at higher strains, and that the stresses in shear are not linear with increasing shear strain. The new constitutive model is a differential model, including both an "elastic" term, of the Mooney type and a nonlinear viscoelastic term. The latter allows for the change in relaxation behaviour with strain, by modifying an upper convected multimode Maxwell model with a damping function. The model shows good agreement with the experimental shear results and could be used to describe other types of data.

Animals↗
PubMed2001

[The ultrastructure of bone morphogenetic protein 2 gene transfected human periodontal ligament fibroblasts].

OBJECTIVE: To observe the ultrastructure of bone morphogenetic protein 2 (BMP-2) gene transfected human periodontal ligament fibroblasts (HPDLFs). METHODS: An expression vector for BMP-2 was transfected into HPDLFs by using Lipofect AMINE. The stable expression of BMP-2 was determined by in situ hybridization and immunohistochemistry. The ultrastructure of the transfected cells was examined by transmission electron microscope. RESULTS: The results showed that the BMP-2 gene transfected cells showed expansive endoplasmic reticulum, incremental myelin sheath-like figures and matrix vesicles. The collagenous fibrillae was distributed widely intercellular. CONCLUSIONS: The results suggests that BMP-2 gene transfection tends to accelerate HPDLFs into osteoblast-like cells.

Bone Morphogenetic Protein 2↗
PubMed2001

[Exercise tolerance in relation to ventilatory drive and respiratory muscle function in COPD].

OBJECTIVE: To assess the relationships between exercise tolerance and respiratory drive and respiratory muscle function in COPD. METHODS: 28 patients with COPD and 26 normal subjects were involved in the study. Routine pulmonary function, pulmonary diffusing capacity, P0.1, PImax were measured at rest. Oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE) etc were measured during exercise testing. Borg Scale was recorded simultaneously. Arterial blood gases were measured before and after exercise. RESULTS: (1) PImax in COPD group (40 +/- 15 mm Hg) was significantly lower than that in the normal group [(53 +/- 19) mm Hg, P < 0.05]. P0.1 in COPD group [(2.8 +/- 0.9) mm Hg] was significantly higher than that in the normal group [(2.0 +/- 0.7) mm Hg, P < 0.05]. Inspiratory drive efficacy (VT/P0.1) in COPD group [(0.21 +/- 0.04) L/mm Hg] was significantly lower than that in the normal group [(0.28 +/- 0.07) L/mm Hg, P < 0.05]. P0.1/PImax in COPD group was (0.069 +/- 0.021), significantly higher than that in the normal group [(0.037 +/- 0.009), P < 0.01]. (2) VO2max was correlated with P0.1/Pimax and Borg Scale in COPD patients (r = 0.66, P < 0.01, and r = 0.53, P < 0.05 respectively). Borg Scale was also positively correlated with P0.1/PImax in COPD group (r = 0.49, P < 0.05). CONCLUSION: In addition to airway obstruction and the damaged gas exchange, exercise intolerance in COPD may also be related to the increased respiratory drive and dysfunction of respiratory muscle.

Adult↗
PubMed2001

[Inhibition of glucose transporter 1 overexpression in mesangial cells by rhein].

OBJECTIVE: To evaluate the effect of rhein on the overexpression of glucose transporter 1(GLUT 1) in mesangial cells transfected with GLUT 1 gene in vitro. METHODS: Rat mesangial cells were transduced with the human GLUT 1 gene(MCGT 1) by retrovirus vector. Mesangial cells transduced with bacterial beta-galactosidase(MCLacZ) were used as control. Glucose uptake was detected by 2-deoxyglucose(2-DG). Cell volume, RNA/DNA ratio and protein/DNA ratio were evaluated by flow cytometry analysis. The synthesis of collagen IV and fibronectin were measured by 3H-proline incorporation and flow cytometry. The activity of glutamine: fructose-6-phosphate aminotransferase (GFAT) was assayed by spectrophotometry method. The expression of collagen IV, fibronectin and GFAT were analyzed by RT-PCR. RESULTS: MCGT 1 exhibited a higher 2-DG uptake with increased Vmax value as compared to MCLaZ(741 +/- 60.5) dpm.microgram prot-1 vs (92.2 +/- 9) dpm.microgram prot-1, (P < 0.01), Even cultured in normal glucose concentration, MCGT1 showed cell hypertrophy, including increased cell volume, RNA/DNA and protein/DNA ratios; increased synthesis of extracellular matrix. 3H-proline incorporation significantly enhanced in MCGT1 compared with that in the control(7.0 +/- 0.4) dpm.cell-1 vs (4.6 +/- 0.6) dpm.cell-1, (P < 0.01); and GFAT activity increased to 1.8 fold. Rhein could inhibit 2-DG uptake of MCGT1(560 +/- 64) dpm.microgram prot-1 vs (741 +/- 60.5) dpm.microgram prot-1, (P < 0.05) in a dose-dependent manner, and reverse the cell hypertrophy of MCGT 1. In addition, rhein could diminish the enhanced GFAT activity of MCGT 1 with no influence in mRNA expression. CONCLUSION: It is suggested that glucose transport activity was an important modulator of cellular glucose metabolism in mesangial cells. Rhein could ameliorate the metabolic derangement of MCGT 1 by decreasing glucose uptake. These findings have led us closer to the identification of therapeutic approaches to abort GLUT 1 overexpression in diabetic nephropathy.

Animals↗
PubMed2001

Tamoxifen interacts with NEU/C-ERBB-2 receptor and inhibits growth of human malignant glioma cell lines.

The effects of tamoxifen, an antiestrogen, on the inhibition of protein tyrosine phosphorylation in neu/c-erbB-2 receptor, DNA synthesis and proliferation were evaluated using the malignant glioma cell lines U25 IMG and T98G which overexpressing neu/c-erbB-2. Pretreatment of two cell lines with tamoxifen resulted in a dose dependent inhibition of tyrosine phosphorylation as well as DNA synthesis and cell growth in two cell lines correlatively. The results support the hypothesis that activated protein tyrosine kinase receptors are involved in the proliferation of glioma cells. Tamoxifen may be useful in the treatment of malignant glioma.

Cell Division↗