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Biomedical subjects

Y Huang

Publications and source records attributed to Y Huang.

At least 1,045 records · Page 58Linked to original sources
PubMed1994

[A study of computer aided simulation system for orthognathic surgery].

How easily to stimulate the orthognathic surgery with high accuracy and good reliability and visually explain the prediction of surgery to the patient with maxillomandibular deformities remains a key focus in oral and maxillofacial surgery. A Computer Aided Simulation System for Orthognathic Surgery (CASSOS) was developed by means of the technique of digital image processing, with which a detailed analysis could automatically be performed, including 71 measurements of distance, degree and ratio for frontal cephalograms and 68 measurements for lateral one with a computer aided diagnosis. A quantitatively surgical simulation for prediction of operation could satisfactorily be done for the clinical use. All data and images were printed by laserjet and color video printer. All procedures were finished in 20 minutes.

Computer Simulation↗
PubMed1994

Characterization of a human myeloid leukemia cell line highly resistant to taxol.

Taxol-resistant sublines of HL-60 myeloid leukemia cells (HL-60/TAX100 and HL-60/TAX1000) have been isolated in vitro by subculturing in progressively higher concentrations of taxol. HL-60/TAX100 and HL-60/TAX1000 cells are capable of continuous growth in the presence of 0.1 microM and 1.0 microM taxol, respectively, and the IC50 (50% growth inhibitory dose) values for taxol for the two sublines are 0.34 and 2.44 microM as compared to 3.1 nM for the parent HL-60 cells. HL-60/TAX100 and HL-60/TAX1000 cells display a variable degree of cross-resistance to taxotere, vincristine and doxorubicin, but are sensitive to the antimetabolite Ara-C. Both HL-60/TAX100 and HL-60/TAX1000 cells over-express MDR-1 m-RNA and the membrane efflux multidrug transporter P-glycoprotein (PGP), as determined by Western blot and immunofluorescence labeling with anti-PGP antibodies. Consequently, exposure of the taxol-resistant cells to [3H]taxol or daunomycin results in the accumulation of significantly lower levels of the two drugs. Co-treatment with cyclosporine (0.5 microgram/ml) or verapamil (10 microM) partially overcomes taxol resistance in HL-60/TAX1000 cells. Following treatment with clinically relevant concentration of taxol (1.0 microM for 24 h), HL-60 but not HL-60/TAX1000 cells display intracellular microtubular bundling, markedly enhanced accumulation of the cells in G2/M phase of cell-cycle and internucleosomal DNA fragmentation associated with apoptosis which is independent of bcl-2 gene expression. These taxol-resistant myeloid leukemia cells may serve as in vitro experimental models for examinating strategies which may have potential applicability for overcoming taxol resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

[DNA sequencing of circumsporozoite protein genes of Plasmodium vivax from four different countries in west Pacific region: comparative study on the flank sequences].

P. vivax CSP gene of 18 isolates from infected blood of patients living in China, Philippines, Solomon Islands and Papua New Guinea in West Pacific region has been sequenced from both terminal end. The total readable sequence in most isolates was about 725 base pair (bp), including the first two repeat units (70-330 bp) to the N terminus, and the last two repeat units to the C terminus (763-1,228 bp). Comparison and analysis of these obtained sequences with the published sequences of N.K., Thai., Belem, Sal-l. and BZL strains showed that:the N and C terminus sequences flanking the centre repeats in CSP gene were highly conserved in all isolates and identical with the 5 published sequences but a double base pair substitution in each end and a remarkable polymorphism in the postrepeat variable region in C terminus were found, including some diversities with obvious geographic characteristics which have not been reported previously.

Animals↗
PubMed1994

Epidemiology of Alzheimer's disease.

In summary, while only a few risk factors for Alzheimer's disease have been identified, several large collaborative studies of elderly populations are currently underway. As measurement techniques improve, the ability to diagnose this disease in its early stages will make the search for risk factors more feasible.

Aged↗
PubMed1994

[Restriction digestion of two kind of baculoviruses and the location of their p10 genes].

The length of SeNPV and LsNPV genomes DNA were calculated to be 133kb and 164kb respectively, according to digestion with 5-8 restriction endonuleases. In order to map p10 gene in Baculoviruses DNA by pure probe, two probe vectors, pAcHP106 and pAcEP102, were constructed with 3'-0. 18kb and 3'-0. 18kb + 5'-0.24kb (coding sequence and promoter) from AcNPV p10 gene. The p10 genes of both baculoviruses, SeNPV and LsNPV, are located with 0.18kb and 0.42kb probes produced by random primer labeling.

Amino Acid Sequence↗
PubMed1994

[Mitochondrial DNA mutation in Leber's hereditary optic neuropathy in China].

Leber's hereditary optic neuropathy (LHON), a typical maternally inherited disease, is caused by a single nucleotide change of G to A at the site of nucleotide 11,788 of mtDNA. We used PCR method to analysis mtDNA from 102 individuals of nineteen pedigrees. The results showed that 67% of the patients (30/45) and 55% (29/53) of the maternal relatives have such a mutation, while no mutation exists in the four normal individuals. The results show that Wallace's mutation is a main cause of LHON in China.

Base Sequence↗
PubMed1994

Antispermatogenic effect of Tripterygium wilfordii and tripchlorolide (T4) on rat gametogenesis and spermatozoa.

The multiglycosides of Tripterygium wilfordii (TII), a ready-made Chinese herbal medicine used for the treatment of rheumatoid arthritis, have been shown to cause oligospermia in patients. In the present study, the antifertility effects of TII and tripchlorolide (T4, isolated from TII) were observed in male rats. In rats fed with TII at a dose of 10 mg.kg.d for 7 weeks, the seminiferous tubules were essentially not influenced. However, most of the sperm heads along the surface of the tubular lumen were transformed from the normal sickle-shaped to round shaped, suggesting a possible mutagenic action. There was minimal testicular change but prominent epididymal spermatozoa damage in all rats treated with T4 (0.05 mg.kg.d) for 7 weeks. The epididymal spermatozoa showed various structural abnormalities, including disrupted connecting pieces and cracked midpieces, and more than 80% of the spermatozoa were decapitated. No significant changes were seen in the main visceral organs. The data suggest that T4 may have good prospects as a male contraceptive.

Animals↗
PubMed1994

[Histological study on repairing experimental pulp chamber floor perforations with yunnan bai-yao in dog].

UNLABELLED: Yunnan Baiyao (YNBY), amalgam, hydroxylapatite and calcium hydroxide were used separately in repairing the experimental pulp chamber floor perforation (PCFP) of dog teeth. The animals were killed at the time of 1, 4, 8 and 12 weeks after experiment. The experimental teeth with periapical tissue were removed and observed their histological changes by optical microscope. The effects that different materials in repairing the tissue of PCFP were observed. Twenty teeth were taken from every dog, each group contained four teeth, the others were used for control group. RESULTS: In initial period (1st, 4th week) inflammatory infiltration was present in PCFP of every group, but the group with YNBY was milder. Pyogenic foci were present in the hydroxylapatite and calcium hydroxide groups. In late stage of experiment (8th and 12th week) inflammatory reactions of each group were alleviated except control group. Epithelial metaplasia and cicatritation were found in the vicinity of perforated area. Dentin cementum and alveolar bone were absorbed in majority of experimental group. It was also observed in the group with YNBY. But in late stage similar cementum formation and alveolar bone neogenesis were found in the perforated area around the repairing materials. It revealed that hemostasis, Promoting Blood Circulation to Remove Stasis and antiphlogistic actions were advantageous to the inflammation, control and repair course of the PCFP. The article discussed that YNBY might promote the repairing of cementum and alveolar bone of perforated area.

Animals↗
PubMed1994

[The Cantonese dialect and mandarin speech audiometric software for computerized audiometer--a preliminary report of exploratory research].

The operation of computerized audiometer depends on softwares. Cassette tapes recorded with 4 Cantonese dialect and 6 Mandarin word lists, both monosyllables and spondees edited and recorded by the author in 1986 were utilized as an original sound source. Each Chinese character and its standard voice were re-edited and saved in computer by means of a Mac digitizing recorder and other computer technic to make a new software. The software is saved in seven 3.5" 2MB floppy dicks. Another copy now is saved in the hardware of a Virtual 320 audiometer at ENT department of Guangdong Provincial Traditional Medical Hospital for further quality checkout and clinical trials. It seems that the quality of this software mostly meets the requirements on recorded speech material suggested by ISO/CD 8253-3 1990.

Audiometry, Speech↗
PubMed1994

Sexing bovine embryos using PCR amplification of bovine SRY sequence.

This study analyses the bovine SRY DNA sequence by direct sequencing procedure, followed by the designation of the PCR primers specific for bovine SRY. Using PCR amplification of bovine SRY gene, the embryo sex was determined. The results of the embryo sex identification were confirmed after the embryo transfer and pregnancies.

Animals↗
PubMed1994

[Changes in cell spreading area and cell surface morphology of Tca8113 line affected by fibronectin].

Morphometric changes in cell spreading area and morphological alternation in cell surface of human tongue squamous cancer line Tca8113 on rat-tail collagen substrata supplemented with different concentration of FN and/or anti-FN serum were quantified and observed with cell culture technique as well as light and scanning electron microscopes. It was found that FN could increase the cell spreading area and also area of lamellar cytoplasm of Tca8113 cells on collagen substrata, and that cells grown on FN-collagen substrata tended to flatten out, stretch out more filopodia, and sink more deeply into the substrata with the FN concentration. The results indicated that FN might relate closely to certain stages in the process of tumor invasion.

Carcinoma, Squamous Cell↗
PubMed1994

[Comparative study of single strand conformation polymorphism of 4.5S RNA gene in enterobacteria].

A recently developed technique, non-isotopic single strand conformation polymorphism analysis (PCR-SSCP), was applied to study the conserved feature of 4.5S RNA gene in enterobacteria. The 4.5S RNA gene was amplified by the polymerase chain reaction, using the template DNA extracted respectively from five strains of Escherichia coli and three strains of different genera in Enterobacteriaceae, i.e. Proteus vulgaris, Serratia marcescens and Enterobacter aerogenes. The PCR products were then carried out SSCP analysis. The experimental results showed that there seemed to be no detectable differences in the size and single strand conformation of 4.5S RNA genes from above strains, except the negative strand conformation of Enterobacter aerogenes. Thus it can be seen that the secondary structures of 4.5S RNA gene in enterobacteria are quite conservative.

Base Sequence↗
PubMed1994

Survival of Alzheimer's disease patients with regard to pattern of care in South Carolina, 1988-1993.

The length of time from diagnosis of AD to death was compared among three groups of AD patients in South Carolina. Each group received a different pattern of care. The survival time from diagnosis to death was longest among those who lived in institutions (mean three years for men, 4.6 years for women), and shortest among those who lived alone in the community (1.7 years for men, two years for women). The longer survival time of those who receive care (either in the community or in facilities) suggests that persons with AD benefit from personal attention to health needs. Providing additional support to family members of those with AD could help patients remain in the community longer, thus maintaining quality of life. For those who have no support in the community, efforts should be made to increase access to facilities.

Aged↗
PubMed1993

High-dose mitoxantrone induces programmed cell death or apoptosis in human myeloid leukemia cells.

Mitoxantrone has been shown in vitro to exhibit a steep dose-response relationship with respect to the clonogenic survival of acute myeloid leukemia cells. In this report, we show that 1-hour exposure of human myeloid leukemia HL-60 and KG-1 cells to mitoxantrone concentrations ranging between 0.1 and 10.0 mumol/L induced internucleosomal DNA fragmentation of approximately 200-bp integer multiples, characteristic of cells undergoing programmed cell death (PCD) or apoptosis. Mitoxantrone-mediated PCD was associated with a steep inhibition of the clonogenic survival of the leukemic cells. In addition, intracellularly, mitoxantrone-induced PCD was associated with a marked induction of c-jun and significant repression of c-myc and BCL-2 oncogenes. Pretreatment with the protein kinase C stimulator phorbol myristate acetate enhanced mitoxantrone-induced internucleosomal DNA fragmentation, whereas protein kinase C inhibitors staurosporine and H7 had no effect. These findings suggest that PCD is a potential mechanism underlying the steep dose-response relationship of mitoxantrone to the inhibition of clonogenic survival of acute myeloid leukemia cells.

Apoptosis↗
PubMed1993

Phosphoenolpyruvate and creatine phosphate augment ATP and magnesium-dependent, Fc epsilon RI-mediated activation of phospholipase C in RBL cell ghosts.

We have previously reported that Fc epsilon RI-mediated activation of PLC occurs in plasma membrane vesicles derived from RBL cells. This activity is dependent on ATP and magnesium, and is greatly enhanced by the addition of either PEP or CP. We undertook these studies to determine whether these compounds augment Fc epsilon RI-mediated activation of PLC because of their ability to form ATP. The specific findings were 1) the addition of increasing amounts of ATP to the ghost vesicles cannot substitute for the combination of ATP and either PEP or CP; 2) the addition of increasing amounts of ATP or a combination of ATP and either PEP or CP results in similar levels of intravesicular ATP; 3) many metabolically related compounds have some activity to support receptor-mediated PI hydrolysis, but only PEP, CP, and 3-PG give a maximal signal; and 4) the inability of ATP alone to support optimal receptor-mediated PI hydrolysis does not appear to be due to the accumulation of ADP is only modestly inhibitory. Taken together, these data are evidence that augmentation of Fc epsilon RI-mediated PI hydrolysis by PEP and CP is not explained simply by the ability of these compounds to generate intravesicular ATP.

Adenosine Triphosphate↗
PubMed1993

Covalent bond changes as a driving force in enzyme catalysis.

A procedure is developed for assessing covalent and noncovalent aspects of the acylation of alpha-chymotrypsin (alpha-Ct) by the substrate trifluoroethyl furoate (S) to form furoyl-chymotrypsin (F-Ct) and trifluoroethanol (P1). The free energy change (-4.31 kcal/mol) for the acylation at pH 7, alpha-Ct+S <--> F-Ct+P1, contains contributions from covalent bond changes as well as noncovalent changes. The noncovalent changes are considered to be manifested in the structures of alpha-Ct and F-Ct, and a noncovalent free energy difference between alpha-Ct and F-Ct has been evaluated from the difference in unfolding free energy changes for these proteins. The unfolding free energy changes demonstrate that F-Ct is 1.6 kcal/mol less stable than alpha-Ct at pH7. Thus, despite an overall favorable free energy change for acyl-enzyme formation (-4.31 kcal/mol), covalent linkage of the furoyl moiety to the active site is thermodynamically destabilizing to the enzyme. The consequence of this unfavorable effect of the furoyl moiety on the noncovalent free energy is that "binding" of the covalently linked furoyl moiety cannot be the driving force for acylation. The source of free energy driving acylation is the covalent bond-breaking and bond-making involved in transesterification of the furoyl group to the enzyme. Since the (noncovalent) Michaelis complex between alpha-Ct and substrate is significantly more stable (thermodynamically) than F-Ct, a substantial amount of noncovalent free energy must be given up on forming F-Ct. The destabilization residing in F-Ct is consistent with the possibility that energy transduction occurs when the Michaelis complex is converted to F-Ct and that destabilization is relieved on reaching the next activated complex.

Acylation↗