Biomedical subjects

J Huang

Publications and source records attributed to J Huang.

At least 199 records · Page 11Linked to original sources

PubMed2001

[One stage otoplasty treatment for congenital malformations of the auricle and middle ear].

OBJECTIVE: To investigate the application of one stage otoplasty for congenital atresia of the external acoustic canal and malformations of the middle ear and the auricle. METHOD: Patients with the ear malformations were given surgical reconstruction of one stage otoplasty. The auricle was reconstructed with the rib which was encapsulated with the superthin temporal flap. According to the malformations of the middle ear in patients, I style tympanoplasty and III style tympanoplasty were carried out respectively. All patients were performed myringoplasty with temporal fascia and reconstructed the external acoustic canal with full thickness skin-grafting. RESULT: A long term follow-up (4-6 years) demonstrated that 11 ears were survival of which 8 ears figuration were ideal. The hearing improvement was observed in all patients. CONCLUSION: One stage otoplasty is effective for treatment of the congenital malformations of the external and middle ear.

Adult↗

PubMed2001

[A survey of pollens in Chongqing].

OBJECTIVE: In order to investigate the variety of the airborne pollen in Chongqing. METHOD: The diffusions pattern of airborne pollens in two areas of Chongqing was investigated for one year from October 1999 to September 2000. The slides were exposed daily through one year. RESULT: The peak of spreading was in March in spring and in Autumn from September to October. The test on the pollen patients shows that the main resulting pollen is in Autumn. CONCLUSION: The airborne pollen peak in Chongqing in spring prone to the influence of temperature, wind power and rain amount.

Allergens↗

PubMed2001

[Diagnosis and surgical treatment of carotid body tumor].

OBJECTIVE: To promote the rate of diagnosis and successful rate of operation for carotid body tumor. METHOD: 26 cases of the 30 patients with carotid body tumor were performed by DSA and 5 cases of them, feeding arteries of tumor were embolized with gelfoam through superlective catheterization, preoperativelly. The tumor was resected under carotid adventitial plane in 12 cases, with extracervical artery in 8 cases and with tumor-carotid segment block in 10 cases. RESULT: Of the 30 cases, no one died from operation or cerebral vascular complications. DSA plays a significant role in diagnosis of the tumor. Intraoperative bleeding can be remarkably reduced if feeding arteries were embolized preoperativelly. The tumor fixed to segment of the carotid arteries block was resected and the reconstruction of vasculature was unnecessary as soon as candidates were certified to be qualified by carotid training and DSA or/and TCD tests. Follow up of these 30 patients revealed that 25 of them survived free from cerebrovascular complications and tumor recurrence for 5 months-10 years. 1 of them died from traffic accident 2 year after operation, 4 of them had lost communication. CONCLUSION: DSA is a most authritative approach for diagnosis of carotid body tumor, DSA and TCD tests play a key role to resect carotid artery without reconstruction. Successful operation based on a precise preoperative evaluation, choice of operative ways and proper procedure.

Adult↗

PubMed2001

[Prediction of retention parameters of explosives by artificial neural network].

The quantitative relationship between the retention parameters and the structure of explosives is discussed. Molecular topological indices are used to represent the structure. Based on the back-propagation algorithm, a quantitative model was established after a training process of a train-set containing 20 explosives being completed. The Sigmoid function was chosen as the transmit function. The retention parameters (log kappa w and S) acted as output vectors, while molecular connecting indices (0 chi, 1 chi, 2 chi) and edge adjacent indices(epsilon) acted as input vectors. The input vectors were normalized in the range of -3-3 and the output vectors were normalized in the range of 0-1. The accuracy of network was 0.5 and the beginning value of studying pace (eta) was 0.2, the momentum factor (alpha) was 0.5. The results showed that the yield model reflected the relationship between the structure and retention index of compounds, and had high accuracy. Most of the relative errors were below +/- 5%.

English Abstract↗

PubMed2001

[Cloning and efficient expression of cytokine human MK in E. coli].

For cloning the cytokine human Midkine (MK) gene, we designed by PCgene program and synthesized a pair of PCR specific primers according to the reported human MK cDNA sequence. Total cellular RNA was extracted from a human hepatoblastoma cell line HepG2, and then the target DNA fragment was obtained by RT-PCR and subcloned into plasmid pUC118. Checked with radioisotope sequencing and ABI 377A sequencer, the nucleotide sequence of the cloned MK cDNA was identical with the reported one. A prokaryotic expression vector, named pBV220, was used to express the MK protein efficiently in E. coli strain TG1 and a predicted band of 16.5 kD in Mr by 15% SDS-PAGE was found. The expressed recombinant protein was found in insoluble aggregated form and accounted for about 31.21% of the total cellular proteins. The first 15 N-terminal amino acid sequence analysis of this protein by Edman degradation method showed that it was accordant with that predicted from the cDNA sequence. The activity of neurite outgrowth-promoting of the MK crude samples was tested with brain cells isolated from 18-day embryos of SD rat.

Animals↗

PubMed2001

The clinical study of Healon 5 in phacoemulsification and IOL implantation.

PURPOSE: To compare a new ophthalmic viscoelastic device (OVD) Healon 5 with two other kinds of OVDs commonly used in China during phacoemulsification and intraocular lens (IOL) implantation in terms of removal time, intraocular pressure, corneal and anterior chamber response. METHODS: This prospective randomized study, in which patients and observers are masked, comprises niety eyes. They were randomly divided into 3 groups with different OVDs. Healon 5 (sodium hyaluronate 5,000 2.3%) was compared with Healon GV (sodium hyaluronate 7,000 1.4%) and Iviz (sodium hyaluronate 1.0%). The surgeries were performed with temporal corneal incision, phacoemulsification in situ and foldable lens intracapsular implantation. The characteristic and the removal time of the viscoelastic material as well as the postoperative IOP, corneal reaction and anterior chamber reactions of the eyes were observed preoperatively and 24 hrs postoperatively. Exclusion criteria were glaucoma, a preoperative dilated pupil diameter smaller than 5.0 mm, proliferative diabetic retinopathy, significant corneal pathology or a history of uveitis. RESULTS: The removal time was 47.42 +/- 13.09 seconds in Healon 5, 16.50 +/- 5.45 in Healon GV and 15.83 +/- 7.40 in Iviz. The removal time of Healon 5 group was significantly longer than that of the other groups (P = 0.000). There is no significant IOP change 24 hours postoperatively and the difference of intraocular pressure among three groups was not significant (P > 0.05). Healon 5 group had the slightest corneal and anterior chamber response, followed by Healon GV and Iviz. CONCLUSION: Although takes longer time to remove, Healon 5 is an ideal viscoelastic material for its superior space maintenance capacity and high dispersity which provides superior protection of endothelial cells compared to Healon GV and Iviz.

Anterior Chamber↗

PubMed2001

[The inhibitory effect of mitomycin C applied by intracapsular method on rabbit lens epithelial cells: an experimental study of after-cataract].

OBJECTIVE: To study the inhibitory effect of Mitomycin C applied by intracapsular infusion method on rabbit lens epithelial cells and its intraocular toxicity. METHODS: 0.2 ml Mitomycin C with different concentration (0.1 mg/ml, 0.2 mg/ml, 0.4 mg/ml) was injected into the capsular bags of the rabbits' lens during the hydrodissection of phacoemulsification. The drug was exposed to the lens epithelial cells directly and transiently. In the two-month follow-up after the operation, the posterior capsule opacification and the change of intraocular pressure were observed and compared between the control group and the experimental group; the histopathologic and the ultrastructural changes were also observed. RESULTS: For clinical study in the rabbit, the posterior capsule opacification only appeared in the control group two weeks after the operation. Four weeks after the operation, the posterior capsular opacification in the eyes of experimental group was not so obvious as that of the control group. The higher the concentration of the drugs, the less the posterior capsule opacification was shown. There was no obvious difference in the postoperative inflammation between the control group and the low, middle-concentration experimental group. Slight toxic reaction was shown on the rabbits' eyes of the high-concentration experimental group in the early stage after the operation. The histopathologic examination showed that the proliferation of lens epithelial cells in the control group was more obvious than that in the experimental group. Mitomycin C could cause the degeneration of lens epithelial cells. The degree of degeneration was related to the drug's concentration. The ciliary bodies of the rabbits' eyes in the high-concentration experimental group were infiltrated by inflammatory cells and bled slightly. CONCLUSION: Mitomycin C can inhibit the proliferation of lens epithelial cells effectively. Its intensity is related to the drug's concentration. It's a safe and effective drug in the prevention of after-cataract when the concentration of 0.1-0.2 mg/ml was applied in the capsular bag.

Animals↗

PubMed2001

[Changes of tangent time constant in the transformation of F-V curve configuration in COPD and cor pulmonale patients and clinical implications].

OBJECTIVE: To explore the changes of tangent time constant (tau t) in the transformation of F-V curve configuration in COPD and cor pulmonale patients and clinical implications. METHODS: We determined the F-V curves in 90 COPD patients (43 with chronic bronchitis, 47 with emphysema) and 31 complicated with cor pulmonale; all patients were in the ameliorated period. The tau t at high, mid and low lung volumes, tau t75, tau t50, tau t25, were measured on each F-V curve. RESULTS: 1. Normal ranges: F-V curve configuration with plateau, linear, convex and concave types; |tau t75| > ls or < ls; tau t25 < ls; tau t relationship with "adolescent fashion" or "old fashion". 2. Light and moderate abnormality: With convex type; |tau t75| < ls; tau t25 approximately = ls or > ls; "trumpet fashion" changes. 3. Serious abnormality: With hyperbolic type; |tau t75| < ls; tau t25 = 4s-10s; "tower fashion" changes. CONCLUSION: Hyperbolic type, extreme prolongation of tau t25 and "tower fashion" changes can be assigned as 3 important indices to assess the severity of disease. The convenience and correctness of the method may be available for clinical application.

Adult↗

PubMed2001

[Preservative surgery of medial wall pyriform sinus cancer].

OBJECTIVE: To study the surgical methods and functional outcome of preservative surgery for medial wall pyriform sinus cancer. METHODS: Seventy-one patients with medial wall pyriform sinus cancer, who were treated surgically between 1985 and 1997, were reviewed. Of the 71 cases, 49 underwent preservative surgery, and 22 total laryngectomy. Preservative surgical procedure was defined as follows: 1. Extent of resection: Supraglottic horizontal partial laryngectomy and resection of medial wall of pyriform sinus were performed in patients without fixation of the true vocal cord, and the section extended to paraglottic space, partial lateral wall of pyriform sinus, preepigottic space, superior-posterior of thyroid cartilage in those with restrained vocal cord motility. Supracricoid hemilaryngopharyngectomy and resection of medical wall and partial lateral wall of pyriform sinus were practiced in those with fixed hemilarynx. Cricoid ring and cervical esophagus were removed partially if the pyriform sinus apex was involved. 2. Reconstruction: Larynx: the remains of epiglottis, perichondrium of thyroid cartilage, the infrahyoid muscular fascia, and the platysmal flap were utilized to restore the defects of larynx. Pyriform sinus: Suturing the remaining pharyngeal mucosa directly to cover the wound if the defect was relatively small. For the large defect produced by extended resections, the pectoralis major myocutaneous flap and deltopectoral flap were used. 3. Surgical treatment of cervical lymphaden: Sixty five out of the 71 cases (91.5%) underwent neck dissection. Of which ipsilateral neck dissection were done in 39 cases, and bilateral neck dissection in 26 cases. 4. All patients received postoperative radiotherapy with doses of 60-75 Gy. RESULTS: In the group of preservative surgery the 3- and 5-year survival rates were 63.4% and 49.6% respectively, whereas those in the total laryngectomy group were 52.4% and 42.4% respectively. Of the 49 cases with preservative surgery, 71.4% (35/49) had all laryngeal functions restored and 28.6% (14/49) partially restored. CONCLUSION: Despite the fact that the medial wall pyriform sinus cancer tends to have laryngeal invasion, preservative surgery can be practiced for the majority of the cases with the lesions entirely removed.

Adult↗

PubMed2001

[Determination of 10 elements in the 12 kinds of Chinese traditional medicines by AAS].

The 10 kinds of inorganic elements were determined in 12 kinds of Chinese traditional medicines. The relation showed that there were numerous inorganic elements in the traditional chinese medicines. The relation between these inorganic elements and the efficacies of these medicines was studied and the efficacies of these Chinese traditional medicines were discussed. The efficacies of these traditional medicines were greatly influenced by the content of inorganic elements. To guarantee the efficacies of these traditional medicines, the reasonable control lines concerned with the content of inorganic elements shall be established and the lines will be discussed in the future.

Calcium↗

PubMed2001

[Some spectrum methods on the structures of metal phthalocyanine].

The recent progress in some spectrum methods on the structures of metal phthalocyanine was introduced. IR and UV/Vis spectral properties of phthalocyanine were presented systematically, especially the effect of the types, numbers and positions of the peripheral substituted groups as well as the different aggregation states in solution on the UV/Vis spectra, the characterization method of the isomers of tetra-substituted metal-phthalocyanine by NMR was also discussed.

Indoles↗

PubMed2001

[Determination of naoning pian by multi-wavelength linear regression method].

Assay of naoning pian was reported by multi-wavelength linear regression method in this paper. The program was edited by BASIC. The recoveries and RSD of pyramidon and caffeine were 98.03%-100.9%, 1.0% and 97.77%-99.39%, 0.61%, respectively. This method could be used for the determination of two components in naoning pian without separation. The method was simple, rapid, and results were satisfactory.

Analgesics, Non-Narcotic↗

PubMed2001

Liver transplantation for patients with hepatitis B virus-related diseases.

OBJECTIVES: To summarize the results of the orthotopic liver transplantation (OLT) for HBV-related diseases and assess the efficiency of lamivudine on preventing HBV recurrence. METHODS: From April 1993 to December 2000, 54 patients with HBV-related liver disease were treated by OLT at the Transplantation Center of Sun Yet-sen University of Medical Sciences (SUMS). Seventeen patients who had postnecrotic cirrhosis (PNC) as a result of HBV infection were designated as group 1; 25 patients coexisting hepatocellular carcinoma (HCC) served as group 2; the remaining 12 patients who had no liver disease but fulminant hepatic failure (FHF) due to HBV infection served as group 3. The survival rate, the causes of early death and the HBV recurrence rate under lamivudine monotherapy were retrospectively analyzed. RESULTS: The overall survival rate within 2 months of transplantation was 75.9% and the morbidity in group 3 was obviously higher than in group 1 and group 2; the outcome patients with small HCC was superior to that of patients with large HCC; lamivudine monotherapy can effectively prevent and treat HBV recurrence while no side effect attributable to it had been identified. CONCLUSION: Combined with the use of lamivudine, liver transplantation can be justified in patients with fulminant hepatitis B, hepatitis B-related liver cirrhosis and coexisting small HCC or even selected large HCC.

Antiviral Agents↗

PubMed2000

DNA ligase IV and XRCC4 form a stable mixed tetramer that functions synergistically with other repair factors in a cell-free end-joining system.

Repair of DNA double-strand breaks in mammalian cells occurs via a direct nonhomologous end-joining pathway. Although this pathway can be studied in vivo and in crude cell-free systems, a deeper understanding of the mechanism requires reconstitution with purified enzymes. We have expressed and purified a complex of two proteins that are critical for double-strand break repair, DNA ligase IV (DNL IV) and XRCC4. The complex is homogeneous, with a molecular mass of about 300,000 Da, suggestive of a mixed tetramer containing two copies of each polypeptide. The presence of multiple copies of DNL IV was confirmed in an experiment where different epitope-tagged forms of DNL IV were recovered simultaneously in the same complex. Cross-linking suggests that an XRCC4.XRCC4 dimer interface forms the core of the tetramer, and that the DNL IV polypeptides are in contact with XRCC4 but not with one another. Purified DNL IV.XRCC4 complex functioned synergistically with Ku protein, the DNA-dependent protein kinase catalytic subunit, and other repair factors in a cell-free end-joining assay. We suggest that a dyad-symmetric DNL IV.XRCC4 tetramer bridges the two ends of the broken DNA and catalyzes the coordinate ligation of the two DNA strands.

Animals↗

PubMed2000

T7 RNA polymerase elongation complex structure and movement.

We have characterized T7RNAP elongation complexes (ECs) halted at different positions on a single template using a combination of digestion with exonuclease III, lambda exonuclease, RNAse T1, and treatment with KMnO(4). Our results indicate that the transcription bubble is approximately nine bases long and that the RNA:DNA hybrid is 7-8 bp in size. An additional four to six bases of RNA immediately 5' to the hybrid interact with the RNAP, probably with a site on the N-terminal domain. When ECs with transcripts of different length were probed in the presence or absence of the incoming NTP we found that the position of the EC on the template and the RNA shifted downstream upon NTP binding. NTP binding also restricted the lateral mobility of the complex on the template. Our results indicate that, in the absence of bound NTP, the RNAP is relatively free to slide on the template around a position that usually lies one to two bases upstream of the position from which NTP binding and bond formation occur. NTP binding stabilizes the RNAP in the post-translocated position and keeps it from sliding upstream, either due directly to RNAP:NTP:template interactions, or to an isomerization which causes the fingers subdomain of the RNAP to clamp down on the downstream end of the template strand.

Bacteriophage T7↗

PubMed2000

Purification of recombinant adeno-associated virus vectors by column chromatography and its performance in vivo.

Recombinant adeno-associated virus (AAV) holds much promise for human gene therapy. While evidence indicates that AAV mediates long-term gene transfer in several different tissues, difficulty in preparing and purifying this viral vector in large quantities remains a major obstacle for evaluating AAV vectors in clinical trials. The current method of purification, based on sedimentation through cesium chloride, is not scaleable and yields product of insufficient quality. In this article we report a new technique for purifying AAV, using a fully closed two-column chromatography system. Yields of AAV vectors purified by this method are high, potency is increased, and the purity of column-purified preparations is substantially improved. We previously reported a novel method to generate AAV based on an AAV Rep/Cap-containing cell line (B50) and an Ad-AAV hybrid virus, which is amenable to scale-up in bioreactors. By combining the new, fully scaleable purification process we report here with the B50/hybrid production method, it would be feasible to prepare AAV vectors to the scale and purity required for clinical and potential commercial applications.

Animals↗

PubMed2000

Continuous on-line true titrations by feedback-based flow ratiometry. The principle of compensating errors

We introduce a new concept for continuous on-line titrations based on feedback-controlled flow ratiometry and the principle of compensating errors. The system has been thoroughly tested by applying it to acid-base neutralization titrations with indicator-based end point detection. In a typical case, the total flow (FT, consisting of the sample and the titrant flows) is held constant while the titrant (e.g., a standard base containing an indicator) flow FB varies linearly in response to a controller output voltage. The sample (e.g., an acidic solution to be titrated) flow FA constitutes the makeup and thus also varies (FA = FT - FB). The status of the indicator color in the mixed stream is monitored by an optical detector and used either for governing the controller output or for interpreting the results of the titration. Three methods (PID based control, fixed triangular wave control, and feedback-based triangular wave control implemented on a PC) were examined. In the last and the most successful approach, the titrant flow is initially ramped upward linearly. At the instant a change in the color is sensed by the detector, the titrant flow rate FH is higher than the true equivalence flow rate FE because of the lag time between the first compositional change and its detection. The sensing of the change in color causes the system output to immediately reverse its ramp direction such that the titrant flow now goes down linearly at the same rate. At the instant a change in color, in the opposite direction this time, is again sensed, the titrant flow rate FL is lower than FE by exactly the same amount that FH was higher than FE. This principle of compensating errors (FE = (FH + FL)/2) allows true titrations with excellent reproducibility and speed (0.6% RSD at 3 s/titration and 0.2% RSD at 10 s/titration) and titrant volume consumption as little as 12 microL/titration and solves an old conceptual problem in flow based titrations.

Journal Article↗

PubMed2000

Misincorporation by wild-type and mutant T7 RNA polymerases: identification of interactions that reduce misincorporation rates by stabilizing the catalytically incompetent open conformation.

We have characterized the misincorporation properties of wild-type (wt) T7 RNAP and of 45 T7RNAP point mutants. The wt enzyme selects strongly against incorporation of an incorrect nucleotide. From the measured rates of misincorporation, an average error frequency of 1 in 2 x 10(4) is estimated. RNAs bearing 3'-mismatches are extended more slowly than correctly paired 3'-termini, and mismatches one or two bases away from the RNA 3'-end can also slow extension severely even when the 3'-base is correctly paired. Though it has been reported that T7RNAP has a 3' --> 5' nuclease activity, we were unable to detect any endogenous T7RNAP RNase activity in elongation complexes. Pyrophosphorolysis was detected but does not appear to contribute to proofreading. Therefore, unlike other RNAPs, T7RNAP fidelity appears to depend entirely on discrimination against incorporation of the incorrect nucleotide and not on post-misincorporation proofreading. Alanine substitution of the H784 side chain, which interacts with the 3' RNA.template base pair, increases both misincorporation and mismatch extension, while substitutions at G640, F644, and G645 increase misincorporation, but not mismatch extension. The latter three amino acids are in a part of the RNAP which interacts with the templating base and with the base immediately 5' to the templating base. Mutation of these amino acids not only increases misincorporation, but also eliminates pausing during promoter clearance. The effects of these mutations and the interactions observed in a crystal structure of a transcribing complex indicate that these mutations disrupt interactions which limit misincorporation rates by stabilizing the catalytically incompetent open conformation of the RNAP.

Alanine↗