Biomedical subjects

Yong Qin

Publications and source records attributed to Yong Qin.

36 records · Page 2Linked to original sources

PubMed2005

Low-temperature synthesis of amorphous carbon nanocoils via acetylene coupling on copper nanocrystal surfaces at 468 K: a reaction mechanism analysis.

A new type of amorphous helical carbon nanofibers has been synthesized using copper nanocatalysts and an acetylene gas source at atmospheric pressure. The nanofibers are grown at 468 K, which is the lowest temperature by ordinary metal-catalyzed thermal chemical vapor deposition of hydrocarbon, and exhibit a symmetric growth mode in the form of twin helices. IR, XRD, Raman, and C/H molar ratio analyses reveal a polymer-like structure with a weak trans-polyacetylene feature. The nanofibers are a mixture of solid polymers and a small amount of carbon. A reaction mechanism has been proposed on the basis of the previous studies of acetylene adsorption, desorption properties, and surface reactions on copper (111), (110), and (001) planes under ultrahigh-vacuum (UHV) conditions as well as the results obtained in our study. The reaction mechanism of acetylene on copper single-crystal surfaces under UHV conditions indeed reflects the reaction mechanism under practical catalytic conditions at atmospheric pressure. The nanofibers grow mainly via acetylene coupling to solid polymers on copper nanocrystal surfaces. Acetylene also couples to yield small amounts of liquid oligomers and gaseous products, and undergoes slight carbon deposition during the fiber growth.

Acetylene↗

PubMed2005

Synthesis and DNA-binding affinities of monomodified berberines.

Four new monomodified berberines have been synthesized in moderate to good yields starting from berberine and fully characterized by HRMS and 1H NMR. Spectrometric titration and ethidium bromide displacement experiments indicate that these berberine derivatives, especially the one having primary amino group, strongly bind with calf-thymus DNA, presumably via an intercalation mechanism.

Berberine↗

PubMed2005

Synthesis, DNA-binding affinities, and binding mode of berberine dimers.

Six novel berberine dimers (3a-f) were synthesized in 37-84% yield from the reaction of berberrubine (2) with dihaloalkanes of varying lengths from two to seven carbons. Their interactions with calf thymus (CT) DNA and three double helical oligodeoxynucleotides, d(AAGAATTCTT)2, d(AAGCATGCTT)2, and d(TAAGAATTCTTA)2, were investigated by means of fluorometric titration and ethidium bromide (EB) displacement experiments. Compared with the monomeric parent berberine (1), these dimers' DNA-binding affinities increased up to approximately 100-fold, suggesting a cooperative interaction of the two berberine subunits in the molecules. Furthermore, these dimers linked by different spacers show a prominent structure-activity relationship when bound with oligodeoxynucleotides. The relative binding affinities are in the order of 3b>3a>3c>3d>3e>3f with d(AAGAATTCTT)2 and d(TAAGAATTCTTA)2, and 3b>3c>3a>3d>3e>3f with d(AAGCATGCTT)2. Dimer 3b, linked with a propyl chain, exhibits the highest binding affinity. This suggests that a propyl chain may be the most suitable spacer to bridge the two berberine units for DNA binding. Spectrophotometric titration and competitive EB displacement of berberine (1) and dimer 3b indicate that both berberine and its dimers form intercalating complexes with duplex DNA. A larger redshift, a stronger hypochromic effect, and a much higher EB displacement ratio, observed in 3b, indicate that the dimer is in more intimate contact with DNA than berberine. In addition, no obvious binding of canadine (4), a hydrogenated product of berberine, with CT DNA was observed, suggesting critical roles of the quaternary ammonium cation and planar structure in the DNA-binding of berberine.

Base Sequence↗

PubMed2005

Two-step self-assembly of nanodisks into plate-built cylinders through oriented aggregation.

Oriented aggregation-based self-assembly of hexagonal LaF3 nanodisks with cavities into plate-built cylinders proceeding in acidic solution in the absence of any organic additive was disclosed. The self-assembly consists of two steps. First, the nanodisks sequentially aggregated together by coalescence mainly through {100} planes to form larger monocrystalline plates, followed by Ostwald ripening to smooth their surfaces. The holes on the primary nanodisks should be responsible for this intriguing growth. Second, the surface-smoothed plates were stacked face-to-face with each other along the [001] direction to construct the cylinders. The acidic condition was found to be a prerequisite for the oriented aggregations in this system.

Journal Article↗

PubMed2005

Synthesis of linked berberine dimers and their remarkably enhanced DNA-binding affinities.

This communication describes the facile synthesis of five novel berberine dimers and their strong affinities toward double-stranded DNA. These berberine dimers were synthesized in 37-84% yields from the reaction of berberrubine with dihaloalkanes of varying lengths, and fully characterized by HRMS and 1H NMR. Compared with the monomeric parent berberine, these dimers showed greatly enhanced binding affinities up to approximately 100-fold, with two double helical oligodeoxynucleotides, d(AAGAATTCTT)2 and d(TAAGAATTCTTA)2, which was investigated by means of fluorescence spectrometry.

Base Sequence↗

PubMed2005

Spectrometric studies of cytotoxic protoberberine alkaloids binding to double-stranded DNA.

The noncovalent complexes of five cytotoxic protoberberine alkaloids, that is, berberine, palmatine, jatrorrhizine, coptisine, and berberrubine with several double-stranded oligodeoxynucleotides were systematically investigated by using electrospray ionization mass (ESI-MS) and fluorescence spectrometric methods, with the aim of establishing the structure-activity relationships. ESI-MS spectrometric studies indicated that these five alkaloids showed both 1:1 and 1:2 binding stoichiometries with d(AAGAATTCTT)(2), d(AAGGATCCTT)(2), and d(AAGCATGCTT)(2). Their relative binding affinities toward these three double-stranded DNA were semi-quantitatively evaluated by measuring the ratios of the complex signals ([ds+alkaloid-5H](4-)+[ds+2alkaloid-6H](4-)) to those of the duplexes ([ds-4H](4-)) and also by ESI-MS competitive binding experiments. These experiments established the relative binding affinities of five protoberberine alkaloids in the order of palmatine>jatrorrhizine>coptisine>berberine>berberrubine with d(AAGAATTCTT)(2), palmatinecoptisine>jatrorrhizineberberine>berberrubine with d(AAGGATCCTT)(2) and palmatine>jatrorrhizinecoptisine>berberine>berberrubine with d(AAGCATGCTT)(2). Significantly, these alkaloids except berberrubine bound to d(AAGGATCCTT)(2) and d(AAGCATGCTT)(2) with the affinities comparable to Hoechst 33258, a typical DNA minor groove binder. The relative binding preferences of berberine, palmatine, and coptisine with these three double-stranded DNA were further quantitatively assessed by their association constants obtained from fluorescence titration experiments. The values revealed the order of relative binding affinities as berberine>coptisine>palmatine with d(AAGAATTCTT)(2) and coptisine>berberine>palmatine with d(AAGGATCCTT)(2) and d(AAGCATGCTT)(2). These results were not in full agreement with those obtained from ESI-MS experiments, maybe due to the different measuring solution conditions. The results from ESI-MS and fluorescence titration experiments indicated that the sequence selectivities of these five alkaloids were not significant and remarkable AT- or GC-rich DNA binding preferences were not obtained, in contrast to the report that berberine binds preferentially to AT-rich DNA. To provide further insight into the sequence selectivities, the association constants of berberine with d(AAGATATCTT)(2), 5'-AAGTAATCTT-3'/5'-AAGATTACTT-3', d(AAGGGCCCTT)(2), d(AAGGCGCCTT)(2), and 5'-AAGGCCGCTT-3'/5'-AAGCGGCCTT-3', that is double helical DNA from AT-rich to GC-rich sequences, were further measured by fluorescence titration methods. No significant differences in their association constants were observed, suggesting that berberine showed no remarkable sequence selectivities.

Alkaloids↗

PubMed2005

Microstructure and magnetic properties of Fe(x)Ni(1-x) alloy nanoplatelets.

Plate-like nanoparticles (or nanoplatelets) of Fe(x)Ni(1-x) (x = 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) alloy were successfully synthesized through a simple sonochemical method. The shapes of the alloy nanoplatelets with different Fe atom contents are almost same. Their average diameters are about 50 nm, and their average thicknesses are several nanometers. The obtained Fe(x)Ni(1-x) alloy nanoplatelets are single-phased and have a face-centered cubic (FCC) crystal structure. The lattice constants of the alloy nanoplatelets are larger than the corresponding bulk value and increase with increasing Fe content. The surface oxidation of the alloy nanoplatelets leads to the lattice expansion. The alloy nanoplatelet powders are all ferromagnetic, and their saturation magnetizations are slightly lower than the corresponding bulk value. The saturation magnetic field and the coercivity increase with increasing Fe content. Magnetic hysteresis loops along the directions deviating different angles from the nanoplatelets plane are obviously different, indicating that the easy-axis is in the in-plane direction and the magnetization reversal is incoherent mode. The micromagnetic simulation results for the array composed of thirty-six Fe0.6Ni0.4 alloy nanoplatelets fit well with the measured data.

Alloys↗

PubMed2005

[Cerebrovascular accident on perioperative period of head and neck surgery].

OBJECTIVE: To explore the reason and treatment of cerebrovascular accident on perioperative period of head and neck surgery. METHOD: We retrospectively analyzed 8 cases. All of them manifested cerebrovascular accident on perioperative period of head and neck surgery. RESULT: Reasons of cerebrovascular accident on perioperative period of head and neck surgery including rupture of blood vessel or deligation in 3 cases, detachment of the thrombus in 1 case, cerebral hemorrhage in 1 case, complicated causes in 3 cases. CONCLUSION: Head and neck surgery patients may undergo cerebrovascular accident of perioperative period during surgery, injury or rupture of blood vessels is the most important reason. Avoiding injury the major blood vessels during surgery is key point. But unfortunately, for cases of complicated reason, it is very difficult for the surgeons to prevent patients from those accidents.

Adult↗

PubMed2004

Synthesis of enantiopure tert-butanesulfinamide from tert-butanesulfinyloxazolidinone.

A three-step procedure for the preparation of enantiopure tert-butanesulfinamide 6 in 51% overall yield is described starting from (1R,2S)-N-Cbz-1,2-diphenylaminoethanol. The key step is the reaction of tert-butylmagnesium chloride with N-Cbz-4,5-diphenyl-1,2,3-oxathiazolidine-2-oxide 2 to afford the optical pure tert-butylsulfinyl-4,5-diphenyl-1,3-oxazolidinone 5 via an 1,5-alkoxy anion rearrangement, which is then subject to ammonia hydrolysis with LiNH(2) in liquid ammonia to give (R)-tert-butanesulfinamide 6.

Journal Article↗

PubMed2004

[Permanent interstitial implantation of 125I seeds for 5 cases of advanced head and neck cancer].

OBJECTIVE: To observe the effect of 125I seeds implants in advanced head and neck cancer. METHOD: Treatment fields were designed to encompass the tumor/edema volume with a 2-3 cm margin, based on assessment of diagnostic CT images, 125I seeds were inserted into there and permanent left there for brachytherapy in 5 patients with advanced head and neck cancer including recurrent oropharyngeal cancer, supraglottic cancer and occult cancer. RESULT: Local tumor were controlled evidently and the patients suffering were alleviated, but 1 case occurred skin necrosis and 1 case occurred skin necrosis combined with internal carotid rupture. CONCLUSION: Permanent 125I implants offer useful pallition for patients with advanced recurrent head and neck cancer but need prevention fatal complication.

Aged↗

PubMed2003

Syntheses and biological evaluation of vinblastine congeners.

Sixty-two congeners of vinblastine (VLB), primarily with modifications of the piperidine ring in the carbomethoxycleavamine moiety of the binary alkaloid, were synthesized and evaluated for cytotoxicity against murine L1210 leukemia and RCC-2 rat colon cancer cells, and for their ability to inhibit polymerization of microtubular protein at < 10(-6) M, and for induction of spiralization of microtubular protein, and for microtubular disassembly at 10(-4) M concentrations. An ID50 range of >10(7) M concentrations was found for L1210 inhibition by these compounds, with the most active 1000x as potent as vinblastine.

Adenocarcinoma↗

PubMed2003

[Treatment of severe subglottic laryngotracheal stenosis using hyoid graft with sternohyoid muscle flap].

OBJECTIVE: To evaluate the possibility and reliability of the hyoid-sternohyoid graft transfer in the correction of server subglottic laryngotracheal stenosis, and delineate the operation skills and clinical results. METHODS: Seven patients with severe subglottic stenosis underwent laryngotracheal reconstruction using the hyoid grafts with sternohyoid muscle flaps (HG-SHMF). Five of these patients had traumatic subglottic stenosis, one with scar tissue of unknown etiology arising in the subglottic region, another with tracheal narrowing caused by inhalation of hydrochloric acid. RESULTS: All seven patients were successfully decannulated with moderate good voice. The average time from reconstruction to decannulation was 15.4 months. The stent was endoscopically removed with a range of 3 to 22 months; the mean time required for stenting was 9.6 months. Two patients who received additional salvage reconstruction procedures because of graft or stent displacement were extubated with improved voices and satisfactory airway. CONCLUSIONS: The HG-SHMF transfer was a single-stage reconstruction, relatively simple procedure that can restore an adequate airway and a good voice. Patients undergoing laryngotracheal reconstruction with HG-SHMF must have regular, long-term follow-up since graft displacement and recurrent granulation tissue or scar reformation can cause restenosis after an initially successful surgery. This procedure should be used in a large number of patients to further test its reliability.

Adolescent↗

PubMed2003

[Evaluation of laryngotracheal stenosis with spiral CT three-dimensional images and clinical application].

OBJECTIVE: To study the use of spiral computed tomography three-dimensional images (SCT-3DI) in the evaluation of patients with laryngotracheal stenosis. The value and utility of SCT-3DI compared with actual endoscopy were also investigated in terms of accuracy of diagnosis and validity of treatment. METHODS: Eight patients with laryngotracheal stenosis were underwent SCT-3DI and regular endoscopy examination preoperatively. Of eight patients, Five had traumatic causes, two with tracheal narrowing due to tracheal granulomas, one with too much scar tissue of unknown etiology in the subglottic area. The location, extent and contour of the stenosis were identified and compared with actual endoscopy findings, and confirmed by surgical procedures. RESULTS: SCT-3DI evaluation was accurate in assessing the length, width and shape of all the laryngotracheal stenosis in our study. The results of SCT-3DI were best correlated with actual endoscopy findings and those found in the surgery. Based on the SCT-3DI, five patients were treated by open surgical techniques including laryngotracheal reconstruction procedures and dilation methods with hyoid grafts or stents. Two undertaken endoscopic treatment with CO2 laser excision of scar tissue or granulomas, one accepted no surgical procedures. All eight patients were successfully decannulated with improved voice and satisfied airway after 6-month postoperative follow-up. CONCLUSIONS: Evaluation of the upper airway with SCT-3DI is useful in the diagnosis, measurement, and definition of the laryngotracheal stenosis. Objective data obtained from SCT-3DI is very helpful for operative scheme. Patients treated with appropriate procedures best suited for every stenosis have reached satisfactory clinical results.

Adult↗

PubMed2003

[CO2 laser endoscopic subtotal arytenoidectomy for bilateral median vocal cord paralysis].

OBJECTIVE: To delineate the surgical procedures and correlated techniques for endoscopic subtotal arytenoidectomy, as well as to discuss their applications and clinical outcomes. METHODS: CO2 Laser endoscopic unilateral arytenoidectomy was performed in eight cases of bilateral median vocal cord paralysis combined with one stage of mucosal micro-anastomosis. All patients suffered from dyspnea in some extent, of which 5 had the history of thyroidectomy and 2 had traumatic causes following esophagectomy and tracheal surgery respectively. One of patient had unknown cause. Six patients had undergone tracheotomy prior to operation or before their referral to our hospital. The airway was evaluated via fibro-optic laryngoscopy, and the voice quality was assessed subjectively by the patients and the surgeon before and after surgery. RESULTS: Following 5-43 months after the surgery, in all cases the function of airway as well as the acceptable voice quality was successfully restored. The tracheotomy done before operation in six patients was decannulated within the mean time of 44.2 days post-operation. CONCLUSION: The endoscopic approach for CO2 laser unilateral arytenoidectomy may lead to better restoration of an adequate airway and satisfying phonation without postoperative aspiration. Mucosal micro-anastomosis can prevent the formation of granulation or scar tissue thus promotes the healing processes. This procedure is simpler than other ordinary surgical methods, and could be a satisfactory alternation of treatment for bilateral median vocal cord paralysis.

Aged↗

PubMed2003

[Studies on chemical constituents in leafs of Ilex kudingcha].

OBJECTIVE: To study chemical constituents of Ilex kudingcha. METHOD: The constituents were isolated by chromatographic method and the structures were identified on the basis of spectral analysis. RESULT: Seven compounds, lupeol(I); 3 beta-hydroxyl-lup-20(29)-ene-24-methyl ester(II); lup-20(29)-ene-3 beta-, 24-diol(III); beta-sitosterol(IV); ursolic acid(V); daucosterol (VI); mannitol were obtained(VII). CONCLUSION: I, III, VI and VII compounds were obtained from genus Ilex for the first time.

Ilex↗

PubMed2002

Interaction of tubulin with a new fluorescent analogue of vinblastine.

Vinblastine is an antimitotic agent that has been used extensively in cancer chemotherapy. The biological effects of the drug are believed to be the result of its interaction with tubulin, the major component of cellular microtubules. Fluorescence spectroscopy is a powerful and versatile technique for studying drug-tubulin interactions, but it rarely has been applied to studies involving vinca alkaloids. We have prepared a new fluorescent derivative of vinblastine designed to retain high affinity for tubulin while possessing a fluorophore that absorbs and emits visible light. A coumarin derivative of vinblastine, 17-deacetyl-O-(3-carbonylamino-7-diethylaminocoumarin) vinblastine (F-VLB), was prepared by reaction of 17-deacetylvinblastine with 7-diethylaminocoumarin-3-carbonyl azide. F-VLB was a potent inhibitor of in vitro microtubule assembly (IC(50) = 0.5 microM). F-VLB binding to tubulin was inhibited by vinblastine. Tubulin binding induced an increase in the F-VLB emission intensity and shifted the emission maximum to higher energy (from 500 to 480 nm). The Stokes shift of tubulin-bound F-VLB was about the same as the Stokes shift of the molecule in ethanol, indicating that the tubulin-bound fluorophore is probably on the exterior of the vinblastine binding site. Unlike vinblastine, F-VLB failed to induce self-assembly of tubulin that could be detected by light scattering or electron microscopy, although some self-association could be detected by analytical ultracentrifugation. Equilibrium binding parameters were quantitatively determined by monitoring the change in fluorescence anisotropy of F-VLB upon tubulin binding. The apparent equilibrium constant for F-VLB binding to tubulin [K(a)(app) = (7.7 +/- 0.5) x 10(4) M(-1) at 25 degrees C] was identical to the equilibrium constant for vinblastine binding to 2 microM tubulin (K(1)) measured under similar buffer and temperature conditions using ultracentrifugation [Vulevic, B., Lobert, S., and Correia, J. J. (1997) Biochemistry 36, 12828-12835]. Binding allocolchicine to tubulin did not significantly affect F-VLB's affinity for the protein [K(a)(app) = (9.1 +/- 0.4) x 10(4) M(-1) at 25 degrees C]. Analysis of the steady-state emission spectra yielded a distance between the colchicine and vinca binding sites on tubulin of approximately 40 A. F-VLB bound to paclitaxel- and glutaraldehyde-stabilized microtubules, with approximately equal affinity. We conclude that F-VLB can be used to obtain information about the vinblastine binding site on tubulin under equilibrium conditions.

Animals↗

PubMed2002

Symmetric and helical growth of polyacetylene fibers over a single copper crystal derived from copper tartrate decomposition.

[reaction: see text] Helical polyacetylene fibers with absolutely symmetric structures were prepared by polymerization of acetylene using copper tartrate as a catalyst. There were always only two coiled polyacetylene fibers grown on a single copper nanocrystal. The two coiled fibers had absolutely opposite helical senses but were identical in cycle number, coil diameter, coil length, coil pitch, and fiber diameter.

Journal Article↗

PubMed2002

[Cloning of AE1-c-end cDNA and construction of its expression plasmid for yeast two-hybrid system].

In this study, about 350 bp cDNA fragment was amplified by PCR. After being sequenced, the AE1-c-end gene fragment was cloned into EcoR I-Pst I site of pGADT7 to form AD ends in the yeast two-hybrid system. The recombinant plasmid was transformed into yeast AH109, and the expression in the yeast was observed. The results demonstrate that AE1-c-end was obtained. pGADT7-AE1-c-end has no toxic effect on the yeast. It can serve as a target gene of yeast two-hybrid system.

Cloning, Molecular↗