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Biomedical subjects

Bin Yang

Publications and source records attributed to Bin Yang.

At least 55 records · Page 3Linked to original sources
PubMed2005

Micro-tensile bond strength of three luting resins to human regional dentin.

OBJECTIVES: To evaluate the micro-tensile bonding strength (muTBS) of three luting resins to human regional dentin. METHODS: Dentin disks from non-carious third molars were prepared from different regions (s, superficial dentin; d, deep dentin; c, cervical dentin), and divided into groups based on anatomical locations and luting resins (Super-Bond C&B: SB; Panavia F 2.0: PF; RelyX Unicem: RU): SB-s, SB-d, SB-c; PF-s, PF-d, PF-c; RU-s, RU-d, RU-c. Luting resins were used according to the manufacturers' instructions, to bond 1-mm-diameter PMMA or composite rods to the exposed dentin specimens under a load of 7.5 N, in the self-curing mode. After storage for 1 or 3 days, muTBS was tested at a cross-head speed of 1mm/min. Data were analyzed with ANOVA and Fisher's PLSD test. The bonding interface and fractography analyses were performed with SEM and TEM. RESULTS: ANOVA results showed that muTBS to superficial dentin was significantly higher than to deep or cervical dentin for all three luting resins. SB-s and PF-s, with the highest muTBS, failed primarily cohesively in luting resin. muTBS of SB-d and SB-c were significantly higher than those of PF and RU. RU, with the lowest regional muTBS, failed mostly within demineralized dentin. SEM and TEM showed that adhesive failures in SB and PF occurred at the top of the hybrid layer (HL), but no obvious HL was observed in RU. SIGNIFICANCE: Luting resins with different chemical formulations and applications yield significantly different bond strengths to different regions in human dentin.

Adolescent↗
PubMed2005

Asymmetric synthesis of alpha-substituted beta-amino ketones from sulfinimines (N-sulfinyl imines). synthesis of the indolizidine alkaloid (-)-223A.

Of the possible four stereoisomers, addition of the lithium enolate of 4-heptanone to sulfinimines resulted in only the syn- and anti-alpha-substituted beta-amino ketones. The formation of the major syn-beta-amino ketone was rationalized in terms of addition of the E-enolate to the C-N double bond of the sulfinimine via a six-member chelated chairlike transition state. The enolates of 4-heptanone were generated using LiHMDS in THF where a 1:2.5 E:Z enolate ratio was noted. In diethyl ether the E:Z ratio was 15:1 in favor of the E-enolate and explained in terms of Ireland's transition state model. Here increased steric interactions between the ethyl group and the carbonyl-LiN(TMS)(2) moiety destabilize the transition state leading to the Z-enolate in the poorly coordinating diethyl ether solvent. This new synthesis of syn-alpha-substituted-beta-amino ketones was applied to the concise enantioselective total synthesis of indolizidine (-)-223A, a 5,6,8-trisubstituted alkaloid isolated from the skin of the dendrobatide frog.

Amines↗
PubMed2005

Phase transitions in the liquid-vapor interface of dilute alloys of Bi in Ga: new experimental studies.

We report the results of measurements of x-ray reflectivity and grazing incidence x-ray diffraction from the liquid-vapor interfaces of four dilute alloys of Bi in Ga with mole fractions x(Bi)=0.0032, 0.0023, 0.00037, and 0.000037. The monolayer coverage of the alloys with x(Bi)=0.0023, and x(Bi)=0.00037 is about 0.85 and only very slightly temperature dependent. The monolayer coverage in the lowest-concentration alloy, with x(Bi)=0.000037, ranged from 0.82 at 29 degrees C to 0.58 at 110 degrees C. In none of these alloys, down to the lowest temperature used, 29 degrees C, can we find any evidence for crystallization of the Bi monolayer that segregates as the outermost stratum of the liquid-vapor interface. Drawing on theoretical arguments we propose that the transitions inferred from the second-harmonic generation and plasma generation studies of dilute Bi in Ga alloys are from the liquid state to the hexatic state of the Bi monolayer. The data for the alloy with x(Bi)=0.000037 suggest that near 80 degrees C there is a disordered phase-to-disordered phase transition.

Journal Article↗
PubMed2005

Cloning and functional characterization of a formin-like protein (AtFH8) from Arabidopsis.

The actin cytoskeleton is required for many cellular processes in plant cells. The nucleation process is the rate-limiting step for actin assembly. Formins belong to a new class of conserved actin nucleator, which includes at least 2 formin homology domains, FH1 and FH2, which direct the assembly of unbranched actin filaments. The function of plant formins is quite poorly understood. Here, we provide the first biochemical study of the function of conserved domains of a formin-like protein (AtFH8) from Arabidopsis (Arabidopsis thaliana). The purified recombinant AtFH8(FH1FH2) domain has the ability to nucleate actin filaments in vitro at the barbed end and caps the barbed end of actin filaments, decreasing the rate of subunit addition and dissociation. In addition, purified AtFH8(FH1FH2) binds actin filaments and severs them into short fragments. The proline-rich domain (FH1) of the AtFH8 binds directly to profilin and is necessary for nucleation when actin monomers are profilin bound. However, profilin inhibits the nucleation mediated by AtFH8(FH1FH2) to some extent, but increases the rate of actin filament elongation in the presence of AtFH8(FH1FH2). Moreover, overexpression of the full-length AtFH8 in Arabidopsis causes a prominent change in root hair cell development and its actin organization, indicating the involvement of AtFH8 in polarized cell growth through the actin cytoskeleton.

Actin Cytoskeleton↗
PubMed2005

A vacuum ultraviolet photoionization mass spectrometric study of acetone.

The photoionization and dissociative photoionization of acetone have been studied at the photon energy range of 8-20 eV. Photoionization efficiency spectra for ions CH3COCH3+, CH3+, C2H3+, C3H3+, C3H5+, CH(2-)CO+, CH3CO+, C3H4O+, and CH3COCH2+ have been measured. In addition, the energetics of the dissociative photoionization has been examined by ab initio Gaussian-3 (G3) calculations. The computational results are useful in establishing the dissociation channels near the ionization thresholds. With the help of G3 results, the dissociation channels for the formation of the fragment ions CH3CO+, CH2CO+, CH3+, C3H3+, and CH3COCH2+ have been established. The G3 results are in fair to excellent agreement with the experimental data.

Journal Article↗
PubMed2005

Experimental free-space distribution of entangled photon pairs over 13 km: towards satellite-based global quantum communication.

We report free-space distribution of entangled photon pairs over a noisy ground atmosphere of 13 km. It is shown that the desired entanglement can still survive after both entangled photons have passed through the noisy ground atmosphere with a distance beyond the effective thickness of the aerosphere. This is confirmed by observing a spacelike separated violation of Bell inequality of 2.45+/-0.09. On this basis, we exploit the distributed entangled photon source to demonstrate the Bennett-Brassard 1984 quantum cryptography scheme. The distribution distance of entangled photon pairs achieved in the experiment is for the first time well beyond the effective thickness of the aerosphere, hence presenting a significant step towards satellite-based global quantum communication.

Journal Article↗
PubMed2005

Asymmetric synthesis of beta-amino carbonyl compounds with N-sulfinyl beta-amino Weinreb amides.

[reaction: see text] Diverse organometallic reagents readily add to enantiopure N-sulfinyl beta-amino Weinreb amides providing the corresponding, stable, N-sulfinyl beta-amino carbonyl compounds in good to excellent yields. This new methodology represents a general solution to the problem of beta-amino carbonyl syntheses, which are important chiral building blocks and constituents of natural products. N-Sulfinyl beta-amino Weinreb amides are prepared by reaction of the potassium enolate of N-methoxy N-methylacetamide with sulfinimines (N-sulfinyl imines) or lithium N,O-dimethylhydroxylamine with N-sulfinyl beta-amino esters.

Aldehydes↗
PubMed2005

Two-channel gastric electrical stimulation accelerates delayed gastric emptying induced by vasopressin.

The aim of this study was to investigate the effects of two-channel gastric electrical stimulation (GES) on delayed gastric emptying, gastric dysrhythmias, and motion sickness-like symptoms induced by vasopressin. Seven dogs implanted with four pairs of gastric electrodes and a duodenal cannula were studied in four randomized sessions (saline, vasopressin, single-channel GES, and two-channel GES). The experiment in each session was conducted sequentially as follows: 30-min baseline, ingestion of a liquid meal, 30-min iv infusion of vasopressin or saline, and two 30-min postprandial recordings. In the GES sessions, GES was applied via the first pair of electrodes for single-channel GES or the first and third pairs of electrodes for two-channel GES. Gastric emptying was collected every 15 min via the cannula for a period of 90 min. Results were as follows. (1) Vasopressin induced gastric dysrhythmias, motion sickness-like symptoms, and delayed gastric emptying (P < 0.01, ANOVA). (2) GES normalized gastric dysrhythmias (P < 0.01) but showed no effects on vasopressin-induced emetic response. (3) Two-channel GES improved delayed gastric emptying induced by vasopressin. In comparison with the vasopressin session, two-channel GES, but not single-channel GES, significantly increased gastric emptying at 30 min (43.9+/-12.6 vs. 27.5+/-7.7%; P < 0.03), 60 min (75.3+/-15.1 vs. 54.0+/-17.8%; P < 0.05), and 90 min (91.6+/-9.8 vs. 80.3+/-9.0%; P < 0.05). GES with long pulses is able to normalize gastric dysrhythmias. Two-channel GES improves delayed gastric emptying induced by vasopressin.

Animals↗
PubMed2005

Effect of structural change of collagen fibrils on the durability of dentin bonding.

This study investigates the effect of structural changes of collagen fibrils on the bonding durability of a total etch luting resin (Super-Bond C&B) and a self-etching luting resin (Panavia F 2.0) to dentin. An atomic force microscope (AFM) was used to observe structural changes of intact dentin collagen fibrils after acidic conditionings of two bonding systems. After 90 d water storage and 15,000 thermal cycles (TC) as artificial aging, micro-tensile bond strength (microTBS) was utilized to evaluate the bonding durability of the two bonding systems to dentin. microTBS after 1 d or 90 d water storage without TC were separately measured in control groups. A cross-banding periodicity of about 67 nm along collagen fibrils was seen on demineralized intertubular dentin surfaces in AFM images. For both luting resins, thermal cycling decreased (p < 0.05) microTBS of 1 d and 90 d, compared to controls. Scanning electron microscope and transmission electron microscopic examinations revealed that the top and bottom of hybrid layer (HL) were weak links in the bonding interface over time. The results suggest that the top of HL contains disorganized collagen fibrils from the smear layer which degrade over time. AFM results indicate that the demineralized intact collagen fibrils beneath the smear layer were not denatured during acidic conditioning. However, these collagen fibrils may be structurally unstable due to poor infiltration by resin or loss of resin protection within the HL over time, reducing the long-term microTBS. This process was accelerated by thermal fatigue cycling.

Adhesiveness↗
PubMed2005

Synergistic effects of liquid and gas phase discharges using pulsed high voltage for dyes degradation in the presence of oxygen.

The technology of combined liquid and gas phase discharges (LGD) using pulsed high voltage for dyes degradation was developed in this study. Apparent synergistic effects for Acid orange II (AO) degradation in the presence of oxygen were observed. The enhancement of AO degradation rate was around 302%. Furthermore, higher energy efficiency was obtained comparing with individual liquid phase discharge (LD) or gas phase discharge process (GD). The AO degradation in the presence of oxygen by LGD proceeded through the direct ozone oxidation and the ozone decomposition induced by LD. Important operating parameters such as electrode distance, applied voltage, pulse repetition rate, and types of dyes were further investigated.

Coloring Agents↗
PubMed2005

Laser in situ keratomileusis induced corneal perforation and recurrent corneal epithelial ingrowth.

We report a rare complication of recurrent corneal epithelial cell ingrowth after corneal perforation induced by laser in situ keratomileusis. A corneal flap was made uneventfully with an automatic SCMD microkeratome (Howard Instruments, Inc.). During laser ablation, instead of random burning over the stromal bed, repeated ablation at a single location occurred because of a machine malfunction, resulting in corneal perforation. The flap was replaced and sutured to prevent leakage of aqueous humor. As the cornea healed, the patient's vision was compromised by scar formation, high irregular astigmatism, and epithelial ingrowth. The flap was reopened, and the epithelial cells were removed by thoroughly scraping the flap and stromal bed. However, corneal epithelial ingrowth recurred within a week. The recurrent and progressive epithelial ingrowth further decreased vision, and penetrating keratoplasty was recommended.

Adult↗
PubMed2005

Promoter methylation profiles of tumor suppressor genes in intrahepatic and extrahepatic cholangiocarcinoma.

Recent studies indicate that tumor suppressor genes can be epigenetically silenced through promoter hypermethylation. To further understand epigenetic alterations in cholangiocarcinoma, we have studied the methylation profiles of 12 candidate tumor suppressor genes (APC, E-cadherin/CDH1, MGMT, RASSF1A, GSTP, RAR-beta, p14ARF, p15INK4b, p16INK4a, p73, hMLH1 and DAPK) in 72 cases of cholangiocarcinoma, including equal number cases of intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma. A total of 10 cases of benign biliary epithelia were included as controls. The methylation status of tumor suppressor genes was analyzed using methylation-specific PCR. We found that 85% of all cholangiocarcinomas had methylation of at least one tumor suppressor gene. The frequency of tumor suppressor gene methylation in cholangiocarcinoma was: RASSF1A (65%), p15INK4b (50%), p16INK4a (50%), APC (46%), E-cadherin/CDH1 (43%), p14(ARF) (38%), p73 (36%), MGMT (33%), hMHL1 (25%), GSTP (14%), RAR-beta (14%) and DAPK (3%). Although single tumor suppressor gene methylation can be seen in benign biliary epithelium, methylation of multiple tumor suppressor genes is only seen in cholangiocarcinoma. About 70% (50/72) of the cholangiocarcinomas had three or more tumor suppressor genes methylated and 52% (38/72) of cases had four or more tumor suppressor genes methylated. Concerted methylation of multiple tumor suppressor genes was closely associated with methylation of RASSF1A, p16 and/or hMHL1. Methylation of RASSF1A was more common in extrahepatic cholangiocarcinoma than intrahepatic cholangiocarcinoma (83 vs 47%, P=0.003) while GSTP was more frequently seen in intrahepatic compared to extrahepatic cholangiocarcinoma (31 vs 6%, P=0.012). Our study indicates that methylation of promoter CpG islands of tumor suppressor genes is a common epigenetic event in cholangiocarcinoma. Based on distinct methylation profiles, intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma are two closely related but biologically unique neoplastic processes. Taking advantage of the unique concurrent methylation profile of multiple genes in cholangiocarcinoma may facilitate the distinction of cholangiocarcinoma from benign biliary epithelium in clinical settings.

Bile Duct Neoplasms↗
PubMed2005

TFE3 immunoreactivity in alveolar soft part sarcoma of the uterine cervix: case report.

SUMMARY: : Alveolar soft part sarcoma (ASPS) is an uncommon neoplasm that has only rarely been reported in the female genital tract. We report a case of incidentally discovered ASPS in the uterine cervix of a 39-year-old woman that exhibited immunoreactivity for TFE3, a recently described marker of ASPS. Strong nuclear immunoreactivity for TFE3 in tumors characterized by a chromosomal translocation involving the TFE3 gene has been reported in ASPS and a subset of pediatric renal cell carcinomas. This translocation, t(X;17)(p11;q25), fuses the TFE3 transcription factor gene on Xp11 to a novel gene on 17q25, designated ASPL. In our case, the neoplastic nuclei were strongly positive for TFE3. To the best of our knowledge, this is the first report of ASPS of the female genital tract with immunoreactivity for TFE3. Other interesting findings in our case were the small size of the tumor and the absence of clinical symptoms.

Adult↗
PubMed2005

Inflammation and caspase activation in long-term renal ischemia/reperfusion injury and immunosuppression in rats.

BACKGROUND: We have previously shown the long-term influence of renal ischemia/reperfusion (I/R) injury and immunosuppression on fibrotic genes and apoptosis in a rat model. For the first time, we have now investigated the effects of I/R and immunosuppression on inflammation and caspase activation. METHODS: I/R injury was induced in the right kidney and the left was removed. Cyclosporin (CsA) (10 mg/kg), tacrolimus (0.2 mg/kg), rapamycin (1 mg/kg), or mycophenolate mofetil (MMF) (10 mg/kg) was then administered for 16 weeks. The effects of I/R and immunosuppressants on interstitial inflammation, interleukin (IL)-1beta expression, caspase-1 and caspase-3 activation, tubulointerstitial damage, and fibrosis were evaluated. RESULTS: ED-1+ (a specific rat monocyte/macrophage marker) cells were mainly localized in the tubulointerstitium and periglomerular areas and increased in I/R group compared to controls (P < 0.01). This was further increased by CsA, but decreased by tacrolimus, rapamycin, or MMF (P < 0.05). The 17 kD active IL-1beta remained unchanged, but 35 kD IL-1beta precursor was decreased by rapamycin in comparison with I/R group (P < 0.05). The 45 kD or 20 kD caspase-1 was increased by I/R or CsA, respectively, and decreased by rapamycin (P < 0.05). The 24 kD caspase-3, which proved to be an active caspase-3 subunit, was increased in I/R and CsA groups and deceased by tacrolimus, rapamycin, or MMF (P < 0.05), but not 32 kD precursor or 17 kD active caspase-3. The activity data of caspase-1 and caspase-3 exhibited the same trend as Western blotting data. The staining of active caspase-3 was scattered in kidneys, mainly in tubular and interstitial areas, which was consistent with that of ED-1+ cells. There was a strong positive correlation between interstitial inflammation and 24 kD caspase-3 expression or caspase-3 activity (r = 0.814 or 0.484), all of which were also closely related with urinary protein (r = 0.537, 0.529, or 0.517), serum creatinine (r = 0.463, 0.573, or 0.539), tubulointerstitial damage (r = 0.794, 0.618, or 0.712) and fibrosis (r = 0.651, 0.567, or 0.469), all P < 0.01. CONCLUSION: This study shows that the mechanisms of long-term I/R injury and immunosuppressants treatment include interstitial inflammation and caspase activation, most clearly demonstrated by the 24 kD active caspase-3.

Animals↗
PubMed2005

[The influence of pupil center shift on wavefront-guided laser in situ keratomileusis].

OBJECTIVE: To evaluate the pupil center shift quantitatively after pupil dilation and to investigate its influence on the outcome of wavefront guided LASIK. METHODS: Sixty-three eyes in 32 myopic patients with order RMS higher than 0.35 or were divided into groups A and B, and the Zyoptix LASIK was applied to the patients of both groups In group A, pupil center was used as the center of ablation, while in group B the ablation center was adjusted based on the pupil center shift. RESULTS: A (0.173 +/- 0.114) mm mean pupil center shift was observed in this study, with the maximum 0.51 mm. At 3 months after the operation, there was no significant difference in visual acuity and refraction power between the two groups. However, the reduction of coma was (0.025 +/- 0.137) microm and (0.097 +/- 0.118) microm in groups A and B respectively (t = 2.131, P = 0.037). The change in spherical aberration was significantly different between the two groups. CONCLUSIONS: Pupil center shift after dilation is common. Adjustment of ablation center based on the shift may improve the correction of coma.

Corneal Topography↗
PubMed2005

[Proliferation of corneal epithelium and apoptosis of keratocytes in the rabbit cornea after treatment with 20% ethanol].

OBJECTIVE: To study the proliferation activity of corneal epithelial cells and the apoptosis of keratocytes in the rabbit cornea after treatment with 20% ethanol. The results were compared to the cornea treated with mechanical scraping of the epithelial cells. METHODS: The experimental group consisted of 42 rabbits. One of the two corneas of each rabbit was incised by 8 mm epithelial trephine using in LASEK and was exposed to 20% ethanol (in distilled water) in the trephine for 40 seconds. In the other eye, the corneal epithelium in the central area was mechanically scraped. The rabbits in the experimental group were randomly divided into seven sub-groups. Each sub-group had six rabbits and the rabbits were killed at 0, 4 hours, 1, 3, 5, 8 and 30 days after the surgery. Three rabbits without any treatment were used as blank controls. Immunohistochemical staining (Ki-67 antigen) was performed to detect the proliferation of corneal epithelial cells. Apoptotic cells were detected by TUNEL assay. Number of keratocytes in the central anterior stroma of cornea was determined by counting the total number of cells under 400 x magnification field in hematoxylin-eosin-stained corneal sections. RESULTS: In the ethanol-treated eyes, the number of Ki-67 positive cells peaked 5 days after the treatment in the central corneal epithelium and 1 day after the treatment in the peripheral corneal epithelium. TUNEL-positive cells were detected in the anterior central stromal keratocytes under the epithelial incisions and the number of TUNEL-positive cells reached a peak 4 hours after the treatment. There was no statistically significant difference in the number of central anterior stromal keratocytes between the ethanol-treated group and the controls (P = 0.68). In the mechanical scraping group, the number of Ki-67 positive cells in the peripheral corneal epithelium peaked 3 days after the treatment. The number of Ki-67 positive cells in the peripheral corneal epithelium of the scraping group was greater than that of the ethanol-treated group. TUNEL-positive cells were detected in the anterior central stromal keratocytes and reached a peak 4 hours after the scraping. The number of central anterior stromal keratocytes was decreased maximally 1 day after the scraping (P < 0.01). CONCLUSIONS: The cornea injury caused by treatment with 20% ethanol for 40 seconds is milder than that caused by mechanical scraping. The wound-healing process in the ethanol-treated cornea is faster than that of the cornea treated with scraping. Corneal epithelium treated with 20% ethanol for 40 seconds can protect the stromal keratocytes.

Animals↗
PubMed2005

[Ecological effects of intercrops in comprehensive management patterns of hilly area plum orchard].

The study on the ecological effects of intercrops in four cropping patterns showed that with the increase of multiple cropping, the annual increase of soil organic matter, total N, total P and total K was 5% - 20%, 7% - 40%, 8% - 70% and 15% - 80%, respectively. Potato-soybean had the best benefit in soil and water conservation, followed by cole-peanut, potato-watermelon, and wheat. Compared with control, the average soil erosion module and runoff amount of 4 patterns were decreased by 44.19%, 39.55%, 38.24% and 37.56%, and 22.40%, 9.28%, 24.11% and 21.16%, respectively. Cole-peanut had the highest biomass, being averaged 100 276 kg . hm(-2) annually, and the second was potato-watermelon, with an average of 73 692 kg x hm(-2). Potato-watermelon had the highest productivity, which averaged 37 565 kg x hm(-2) annually, and the second was potato-soybean, averaged 25 934 kg x hm(-2). The efficiency of energy input was in order of cole-peanut, potato-watermelon, potato-soybean, and wheat, and the value was 2.96, 2.08, 2.01 and 0.96, respectively.

Biomass↗