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Biomedical subjects

L Zhang

Publications and source records attributed to L Zhang.

At least 559 records · Page 31Linked to original sources
PubMed2001

[Identification of Mortieralla isabellina M6-22 delta 6-fatty acid desaturase by heterologous expression in Saccharomyces cerevisiae].

Using plasmid pTMICL6 containing delta 6-fatty-acid desaturase gene from Mortieralla isabellina M6-22 as a template, 1.38 kb DNA fragment was amplified by PCR. The fragment was subcloned into the yeast-E. coli shuttle vector pYES2.0, then an expression recombinant plamid pYMID6 containing target gene was constructed. The pYMID6 was transformed into Saccharomyces cerevisiae for expression by LiAc method. It was found to exhibit delta 6-fatty acid desaturase activity in the recombinant S. cerevisiae YMID6 in the presence of exogenous fatty acid substrate linoleic acid under introduction of GAL. Expression of the delta 6-fatty acid desaturase gene under appropriate media and temperature conditions led to the production of gamma-linolenic acid reached 8.69% of the total yeast fatty acid by GC-MS detection. It is the first report about expression of M. isabellina D6D gene in S. cerevisiae.

Fatty Acids↗
PubMed2001

[Effects of angiotensin II on the 3H-TdR incorporation and synthesis of collagen in cultured bovine trabecular meshwork cells].

OBJECTIVE: To investigate the effects of angiotensin II (Ang II) on the cell proliferation and collagen synthesis of bovine trabecular meshwork (TM) cells in vitro. It may probe into the mechanism of primary open-angle glaucoma(POAG). METHODS: (1) The bovine trabecular meshwork cells were cultured and identified by immunohistochemistry method(neuronal specific enolas, NSE, factor related antigan). The growing characteristics and morphological feature of cultured primary and passaged cells were observed by invered microscope and eletron-microscope; (2) Ang II(1 x 10(-7) mol.L-1 and 1 x 10(-8) mol.L-1) and angiotensin receptor type I (AT1) antagonist (losartan) were incubated with cultured TM cells. The cellular proliferation was measured by 3H-thymidine(3H-TdR) incorporation assay and collagen synthesis was indirectly professed though detects the hydroxyproline of medium with chemistry methods. RESULTS: The cells of bovine trabecular meshwork were cultured successfully. Most of them were epithelia type. Ang II increased the TM cells uptake of 3H-TdR and inhibited by losartan partially. Meanwhile the hydroxyproline of medium was increased correspondingly. CONCLUSION: Establishing the method of culturing bovine trabecular meshwork cells is an important method for researching the characteristics of TM cells. Ang II can induce the cell proliferation of bovine TM cells and increase the synthesis of collagen in vitro. The AT1 antagonist may inhibit this cell proliferation effect.

Angiotensin II↗
PubMed2001

[Study on effect of qingkailing injection and its active principle in inducing cell apoptosis in human acute promyelocytic leukemia].

OBJECTIVE: To investigate the mechanism of Qingkailing (QKL) Injection in treating acute promyelocytic leukemia. METHODS: Using MTT technique, cell morphologic method, DNA gel electrophoresis and flow-cytometry to study the human acute promyelocytic leukemia (HL-60) cell apoptosis induced by QKL and its active principle. RESULTS: QKL and its active principle, Baicalin and hyodeoxycholic acid, showed strong cytotoxicity in inhibiting HL-60 cell, the Bezoar cholic acid showed a weaker effect. Apoptosis could be induced after being treated for 6 hrs by the former three principles, showing a typical apoptosis peak under flow-cytometry, but could not be induced by the latter one. CONCLUSION: QKL could induce leukemia cell apoptosis in vitro, which may be one of the mechanisms of QKLI in curing acute promyelocytic leukemia.

Apoptosis↗
PubMed2001

[Effect of huadai xingshen decoction on cerebral somatostatin, arginine vasopressin and somatostatin mRNA expression in vascular dementia rat model].

OBJECTIVE: To study the mechanism of Huadai Xingshen Decoction (HDXSD) in treating vascular dementia (VD). METHODS: Rat model of VD was established by repeated ischemia/reperfusion and treated with HDXSD. Hydergine was taken for positive control. The content of somatostatin (SS), arginine vasopressin (AVP) and SS mRNA expression model rat's cortex and hippocampus were observed. RESULTS: The SS and AVP contents of cortex and hippocampus in model rats were decreased significantly, and the SSmRNA expression in cortex of frontal lobe reduced, too. HDXSD showed an up-regulation on the above-mentioned parameters, and the effect on SS cortex and SS mRNA expression was higher than that of hydergine. CONCLUSION: HDXSD improves intellectual impairment of VD rats by increasing the synthetic ability of SSmRNA and content of AVP, which in turn improve the neurotrophic effect and promote the restoring function of injured neuron.

Animals↗
PubMed2001

[Synthesis and determination for enantiomeric purity of 6-fluoro-L-DOPA].

AIM: To study the synthesis and determination for enantiomeric purity of 6-fluoro-L-3, 4-dihydroxyphenylalanine (6-fluoro-L-DOPA, 6-FDOPA). METHODS: 2-(2-Fluoro-4, 5-dimethoxybenzyl)-N-(diphenylmethylene) glycine tert-butyl ester (8), a new compound, was synthesized from the starting material nitroveratraldehyde via the nucleophilic displacement, reductive iodination, and chiral catalytic phase-transfer alkylation, and 6-FDOPA was prepared from hydrolysis of 8. The enantiomeric purity of 6-FDOPA was determined by HPLC method using a chiral mobil phase and reversed-phase C18 column. RESULTS: The total time of synthesis was less than 90 min, the overall chemical yield from potassium fluoride was about 33%, and the enantiomeric purity was above 95%. CONCLUSION: Large scale production of 6-FDOPA and automatic synthesis of 6-[18F]fluoro-L-DOPA with excellent chemical and entiomeric purity are available. The practical technique was provided for the radiochemical synthesis and entiomeric purity of 6-[18F]fluoro-L-DOPA.

Dihydroxyphenylalanine↗
PubMed2001

[Study on the construction of DYS385 allelic ladder and the genotype distribution in two populations].

OBJECTIVE: We have designed a new method to produce standard DYS385 allelic ladder in order to solve the problem of the accuracy and standardization of STR-PCR typing in forensic practice. METHODS: Nine different PCR amplified DYS385 allelic fragments were isolated from the gel, eluted into the distilled water and reamplified by PCR. The purified allelic fragments were then blunt-end subcloned individually into the pUC plasmid vectors and transfected into competent E. coli DH5 alpha cells. The sequencing results confirmed that the size and the constructure of the inserts were correct. The recombinant plasmids DNA with 9 inserts were then used as templates for reamplification to generate DYS385 standard ladder. RESULTS: A large quantity of standard DYS385 allelic ladder was obtained, with which the genetic polymorphisms of DYS385 locus both in Chinese Han and German populations were studied. CONCLUSION: The STR standard ladder constructed by this method has high value in the forensic application, and the DYS385 locus is robust for forensic analysis.

Alleles↗
PubMed2001

[Comparison between human sperm zona-free hamster ovum penetration assay and in-vitro fertilization].

OBJECTIVE: The research question was whether the result of human sperm zona-free hamsterovum penetration assay (SPA) could serve as an indicator for in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). METHODS: The semen samples of 22 male partners in couples with infertile marriage were assessed for their fertilizing capacity by SPA. The fertilization rate of SPA was compared with that of IVF. RESULTS: The fertilization rates of SPA and IVF were 38.6% +/- 23.5% and 53.5% +/- 28.4% respectively, and a significant correlation between SPA and IVF was observed (rs = 0.7045). CONCLUSION: The result of SPA may be used as a reference indicator for assisting fertilization, IVF or ICSI.

Animals↗
PubMed2001

[Observation of nasal mucosal cilia ultrastructure of Kartagener's syndrome].

OBJECTIVE: To report the ultrastructure of nasal mucosal cilia of Kartagener's syndrome and the operative results of 2 cases. METHODS: Both two cases were underwent endoscopic sinus surgery. Transmission and scanning electron microscopic examinations of nasal mucosa for case 1 were performed. RESULTS: All 2 cases presented situs inversus, chronic paranasal sinusitis and bronchiectasis. The electron microscopic examination showed that the shape of nasal cilia and "9 + 2" structure were normal, but the lack of inner dynein arm of cilia and confused arrangement of central pair of microtubules were confirmed. The recurrent of nasal polyps after 1-year follow-up was observed in case 1. CONCLUSIONS: The disturbance of mucociliary clearance due to congenital ciliary structure defect might be the cause of chronic sinusitis and polyps, which might be one of reasons for poor prognosis after operation and we should pay more close attention.

Adolescent↗
PubMed2001

[Concentration of interleukin-5 and granulocyte-macrophage colony stimulation factor in nasal polyps tissue and its significance].

OBJECTIVE: To study the relationship between the concentration of interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulation factor (GM-CSF) in nasal polyps and its significance. METHODS: The concentration of IL-5, GM-CSF was measured by enzyme linked immunosorbent assay (ELISA) in a total of 38 cases, and the number of eosinophils were counted in the same tissues. RESULTS: The statistical analysis showed that the concentrations of IL-5 and GM-CSF have significant difference (P < 0.05) between the nasal polyps and the control group. There is a positive correlation between the quality of IL-5/GM-CSF and the extent of eosinophils (r = 0.75/0.71). CONCLUSION: This study demonstrated that there are inductive compartments, namely the microenvironment, in which immune-effector and inflammatory cell function is modulated in nasal polyps. A special discussion has been made of eosinophils and IL-5/GM-CSF in the formation of nasal polyps, and the effect of the IL-5/GM-CSF in the accumulation of eosinophils.

Adolescent↗
PubMed2001

[Surgical management of subglottic carcinoma].

OBJECTIVE: To explore the surgical management and evaluate the effect on patients with subglottic cancer. METHODS: Fourteen cases with subglottic carcinoma were treated surgically from 1989 to 1998. There were T1-2N0 lesions in 5 cases, T3N0-2 lesions in 3 cases and T4N0-1 lesions in 6 cases. Eleven cases underwent partial laryngectomy and three cases underwent total laryngectomy. The defects of larynx were reconstructed by using uni-pedicled or bi-pedicled stemohyoid myofascial flap, platysma myocutaneous flap, sternocleidomastoid myoperiosteal flap, thyroid perichondral flap and epiglottis flap accordingly. Unilateral neck dissection was performed on 4 cases and bilateral on one. RESULTS: The function of phonation had been restored in all cases except in 3 patients who underwent total laryngectomy. Seven out eleven(63.6%) were decannulated. The swallowing function was restored in all patients. In all cases the 3 and 5 year survival rates were 78.6%(11/14) and 63.6% (7/11), respectively. CONCLUSIONS: The conservative surgery can be used for the majority of the subglottic carcinoma if the lesions were entirely resected. The proficiency in surgical methods is crucial for the preservation of laryngeal function.

Adult↗
PubMed2001

[Study on vibration mode of different phonatory source and compensation after partial laryngectomy].

OBJECTIVE: To investigate the nature of pathological voice production and compensatory mechanism after partial laryngectomy. METHODS: Vocal function of 93 cases following partial laryngectomy (28 cases of horizontal partial laryngectomy, 35 vertical partial laryngectomy, 30 horizontal-vertical partial laryngectomy) were examined by acoustic analysis, aerodynamic analysis and videostroboscopic examination. RESULTS: Horizontal supraglottic laryngectomy(HL) resulted in slight dysphonia after operation. The cover of vocal fold was hypertrophic and edematous. Mucosa wave was increased. Acoustic analysis showed significant difference between normal and horizontal laryngectomy groups(P < 0.05). Vertical laryngectomy(VL) resulted in moderate-severe dysphonia. Acoustic analysis was significantly worse in VL than in normal group(P < 0.01). The nonglottic phonatory source was the contralateral ventricular fold or contralateral vestibular mucosa (arytenoid mucosa, root mucosa of glottis) to approximate the reconstructed flap. It was noted that contralateral vocal fold did not participate in vibration. Horizontal-vertical partial laryngectomy (HVL) resulted in moderate-severe dysphonia. Acoustic analysis of HVL was significantly worse than that of normal phonation(P < 0.01). The site of compensatory mucosa vibration upon phonation was the contralateral vocal fold or contralateral hypertrophic arytenoid mucosa. The thinner the flap, the better the vocal quality was. Vocal quality of VL was worse than that of HVL in regard to shimmer, jitter, normalized noise energy, maximal phonation time and harmonic-noise ratio, but there was no significant difference between them. CONCLUSIONS: Partial laryngectomy has different vibrating compensatory modes: Voice function of horizontal partial laryngectomy was the best as it preserved the normal vibration mode; vertical partial laryngectomy was the worst with the nonglottic vibrating source of reconstructed flap-ventricular fold. The reconstructed flap, ventricular fold, mucosa of epiglottis and arytenoid take predominantly part in neoglottal vibration. The situation, volume and pliability characteristic of reconstructed flap was also important to vocal quality.

Aged↗
PubMed2001

[Application of an image-guidance system in endoscopic sinus surgery].

OBJECTIVE: To evaluate the advantages of image-guidance system in endoscopic sinus surgery. METHODS: Twenty-eight endoscopic sinus surgery procedures were performed with the help of image-guidance system. There were 11 cases of chronic sinusitis with/or without nasal polyps, 4 juvenile nasopharyngeal angiofibromas, 6 pituitary adenomas, 3 ethmoid ossifying fibromas, 2 nasopharyngeal mixed tumors, 1 nasal leiomyoma, 1 fungal sinusitis, and 1 inverted papilloma. RESULTS: In all cases, the preoperative operation would take 15-30 minutes, the registration rate was 1.3-2.0, the localization accuracy was within 1 mm. Compared with the traditional endoscopic sinus surgery, the operative time did not differ obviously. No complication occurred. CONCLUSIONS: The image-guidance system could identify the operative borders and critical anatomical structures together with the corresponding CT data, especially in cases with anatomical variations, unidentified anatomical landmarks, and intranasal or anterior skull base tumors. Endoscopic sinus surgery, combined with the image-guidance system, provided accurate tumor resection while preserving normal tissue. It could increase surgical effectiveness and decrease overall surgical complications. We believe that the image-guidance system is a useful tool for endoscopic sinus surgery.

Adolescent↗
PubMed2001

Experimental study of the morphology of cerebral bridging vein.

OBJECTIVE: To investigate the morphological properties of pig cerebral bridging vein. METHODS: The morphology and fibre arrangement of 15 cerebral bridging veins obtained from 7 Danish Yorkshire landrace pigs were observed. RESULTS: There was a narrow region at the junction of the cerebral bridging veins and superior sagittal sinus termed "outflow cuff segment". The diameter and length of outflow cuff segment were much smaller and the thickness was higher than those of the cerebral bridging veins ( P < 0.01), and circumferential collagen fibres were most dense in the outflow cuff segment. The opening angle of the outflow cuff segment and the cerebral bridging veins were 115 +/- 4 degrees and 120 +/- 4 degrees ( P > 0.05). CONCLUSIONS: There were differences in fibre arrangement and morphological properties between the outflow cuff segment and the cerebral bridging vein, just like a resistance valve, the outflow cuff segment may play an important role in stabilizing cerebral venous outflow and regulating intracranial pressure.

Animals↗
PubMed2001

[Mössbauer spectroscopy and its application in the study of iron cation behavior in molten slags].

The principle, parameters and determination methods of Mössbauer spectroscopy are summarized. The iron cation behavior in molten slags is analyzed and Mössbauer spectra characteristics of Fe2+, Fetet3+ and Feoct3+ ions are detailed chemically and spetroscopically. The relationship between iron cation behavior and basicity, total iron, Na2O and Al2O3 addition in slags is also discussed here.

English Abstract↗
PubMed2001

[Determination of Pd, Pt and Au by microwave plasma torch atomic emission spectrometry using an on-line clean-up].

In this paper, in the presence of Li+, Na+, K+, Ca2+ and Mg2+, determinations of Pd, Pt and Au by microwave plasma torch atomic emission spectrometry (MPT-AES) using an on-line clean-up were studied. It was shown from the experiments that these interfering matrix elements might be removed with the strong acidic cation exchange resin. The method was applied to the analysis of some practical samples and the results obtained were satisfactory.

Cation Exchange Resins↗
PubMed2001

[In situ IR study of the reaction behavior of clusters [VnCr3-n (mu 3-O) (mu-O2CCH3)6(THF)3]X[n = 0-3, X = Cl-, ClO4-, (VO5)0.5-] and [VnFe3-n(mu 3-O) (mu-O2CCH3)6(THF)3]X(n = 0-3, X = Cl-) in nitrogen atmosphere].

The reaction behavior of the title complexes have been investigated by means of in situ IR in nitrogen atmosphere. It has been found that they enabled the acetic acid to convert to acetone and methane in different temperatures. The results indicate that the sequence of the ketonization reaction activity for the clusters was [V3OAT] > [VFe2OAT], [V2CrOAT] > [Fe3OAT], [VCr2OAT] > [Cr3OAT] [OAT = (mu 3-O) (mu-O2CCH3)6 (THF)3], and the sequence of the methanation reaction activity for the clusters was [Cr3OAT] > [VCr2OAT], [V2CrOAT] > [V3OAT] > [VFe2OAT], [Fe2OAH]. The ketonization reaction activity of [Fe3OAT] were obviously lower than that of [Fe3OAH] [OAH = (mu 3-O) (mu-O2CCH3)6 (H2O)3] and the methanation reaction activity of [Cr3OAT] were also much lower than that of [Cr3OAH]. The difference between [Fe3OAH], [Cr3OAT] and [Fe3OAH], [Cr3OAH] mentioned above were discussed.

English Abstract↗