Biomedical subjects
Publications and source records attributed to Yang Cao.
Tau-leaping methods have recently been proposed for the acceleration of discrete stochastic simulation of chemically reacting systems. This paper considers the numerical stability of these methods. The concept of stochastic absolute stability is defined, discussed, and applied to the following leaping methods: the explicit tau, implicit tau, and trapezoidal tau.
The N-terminal regions, which are highly variable in small heat-shock proteins, were found to be structurally disordered in all the 24 subunits of Methanococcus jannaschii Hsp16.5 oligomer and half of the 12 subunits of wheat Hsp16.9 oligomer. The structural and functional roles of the corresponding region (potentially disordered) in Mycobacterium tuberculosis Hsp16.3, existing as nonamers, were investigated in this work. The data demonstrate that the mutant Hsp16.3 protein with 35 N-terminal residues removed (DeltaN35) existed as trimers/dimers rather than as nonamers, failing to bind the hydrophobic probe (1,1'-bi(4-anilino)naphthalene-5,5'-disulfonic acid) and exhibiting no chaperone-like activity. Nevertheless, another mutant protein with the C-terminal extension (of nine residues) removed, although existing predominantly as dimers, exhibited efficient chaperone-like activity even at room temperatures, indicating that pre-existence as nonamers is not a prerequisite for its chaperone-like activity. Meanwhile, the mutant protein with both the N- and C-terminal ends removed fully exists as a dimer lacking any chaperone-like activity. Furthermore, the N-terminal region alone, either as a synthesized peptide or in fusion protein with glutathione S-transferase, was capable of interacting with denaturing proteins. These observations strongly suggest that the N-terminal region of Hsp16.3 is not only involved in self-oligomerization but also contains the critical site for substrate binding. Such a dual role for the N-terminal region would provide an effective mechanism for the small heat-shock protein to modulate its chaperone-like activity through oligomeric dissociation/reassociation. In addition, this study demonstrated that the wild-type protein was able to form heterononamers with DeltaN35 via subunit exchange at a subunit ratio of 2:1. This implies that the 35 N-terminal residues in three of the nine subunits in the wild-type nonamer are not needed for the assembly of nonamers from trimers and are thus probably structurally disordered.
One of the most important functions of artificial three-dimensional (3D) polymeric scaffolds is to serve as a physical support to provide tissues with an appropriate architecture for in vitro cell culture as well as in vivo tissue regeneration. The production of three-dimensional (3D) polymeric scaffolds with tailored macroporous architecture is thus a crucial step in promoting controlled vascularization and tissue growth within host environments. In this study, 3D poly(lactic-co-glycolic acid) (PLGA) scaffolds were manufactured by a thermally induced phase-separation (TIPS) technique. By controlling the quenching strategy, 3D interconnected PLGA scaffolds with tunable pore size and alignment were obtained and characterized with the use of scanning electron microscopy (SEM). A series of numerical heat-transfer models were established in an effort to describe the cooling process within the PLGA freezing regime. Among them, a two-dimensional (2D) solidification model has proved to be the most successful in describing the quenching of the polymer solution and has the potential to be used to infer the various 3D macroporous architectures created from different quenching conditions.
In this paper we examine the different formulations of Gillespie's stochastic simulation algorithm (SSA) [D. Gillespie, J. Phys. Chem. 81, 2340 (1977)] with respect to computational efficiency, and propose an optimization to improve the efficiency of the direct method. Based on careful timing studies and an analysis of the time-consuming operations, we conclude that for most practical problems the optimized direct method is the most efficient formulation of SSA. This is in contrast to the widely held belief that Gibson and Bruck's next reaction method [M. Gibson and J. Bruck, J. Phys. Chem. A 104, 1876 (2000)] is the best way to implement the SSA for large systems. Our analysis explains the source of the discrepancy.
Whether transforming growth factor-beta2 (TGF-beta2) induces apoptosis of human trabecular meshwork cells was investigated in vitro. Cultured 3-5 passage human trabecular meshwork cells were treated with 0 (control), 0.32, 1, 3.2 ng/ml TGF-beta2 for 48 h and divided into control group and experimental group. The apoptosis of human trabecular meshwork cells was examined by transmission electron microscopy, TUNEL technique and flow cytometry. The results showed characteristic morphologic changes of apoptotic cells were observed under transmission electron microscopy. DNA fragmentation of human trabecular meshwork cells was found by TUNEL technique. Quantitative analysis of flow cytometry showed that percentages of apoptotic human trabecular meshwork cells were (2.79 +/- 0.44)%, (4.43 +/- 1.17)% and (9.60 +/- 2.05)% respectively with different concentrations [1 ng/ml (P<0.05), 3.2 ng/ml (P<0.01)] of TGF-beta2 with the difference being significant between experimental group and control group [(1.41 +/- 0.34)%]. It was concluded that TGF-beta2 can induce apoptosis of human trabecular meshwork cells in vitro and may be involved in the decrease of trabecular meshwork cells in the patients with primary open angle glaucoma and aging of normal people.
Whether tranilast had antagonistic effect on proliferation inhibition and collagen synthesis promotion induced by TGF-beta2 in cultured human trabecular meshwork cells was investigated. Suspension of 1 x 10(4) cultured human trabecular meshwork cells of 3-5 passage was distributed in each well of a 96-well disk and divided into control group and experimental group. After 24 h, 0 microg/ml (control), 12.5 microg/ml, 25 microg/ml, 50 microg/ml tranilast with 3.2 ng/ml TGF-beta2 were added into the incubation medium. Another 24 h later, proliferation and collagen synthesis in cultured human trabecular meshwork cells were examined respectively by using tetrazolium-based semiautomated colormetric (MTT) assay and 3H-proline incorporation with liquid scintillation technique. The results showed absorbance (A) values of the experimental groups were 0.9036 +/- 0.3017, 1.1361 +/-0.1352, 1.2457 +/- 0.1524 according to the different concentrations of tranilast, and 0.8956 +/-0.1903 of the control group. In comparison with the control group, 25 microg/ml (q'= 3.23, P< 0.05), 50 microg/ml (q'=4.70, P<0.01) tranilast significantly antagonized the decrease of the A values induced by TGF-beta2 in the cultured human trabecular meshwork cells. In comparison with the control group [817.37+/-124.21 cpm/10(4) cells], 12.5 microg/ml (620.33+/-80.46 cpm/10(4) cells, q'= 4.26, P<0.05), 25 microg/ml (594.58+/-88.13 cpm/10(4) cells, q'=4.81, P<0.01), 50 microg/ml (418.64+/-67.90 cpm/10(4) cells, q'=8.62, P<0.01) tranilast significantly inhibited the incorporation of 3H-proline into the cultured human trabecular meshwork cells promoted by TGF-beta2 in a dose-dependent manner. It was concluded that tranilast had the antagonistic effect on the proliferation inhibition and collagen synthesis promotion induced by TGF-alpha2 in the cultured human trabecular meshwork cells.
To study whether cultured bovine trabecluar meshwork cells (BTMC) are capable of expressing tTG in protein and at mRNA level, BTMC were cultured in vitro and passaged three times, then the cells were transferred onto or cultured on sterile cover or submitted to isolation of RNA with Trizol, and the expression of tTG was detected by immunohistochemical technique and reverse transcription polymerase chain reaction (RT-PCR) respectively. Our results showed that tTG immunostaining was positive in the cytoplasm and rarely in the nucleus of cultured BTMC. No immunostaining was seen in the negative control. Moreover, a single RT-PCR amplified product whose sequence and size were in accordance with our known parameters was obtained. The expression of tTG in cultured BTMC was confirmed in protein and at mRNA level. BMTC is available more readily for the investigation of the relationship between tTG and primary open-angle glaucoma.
BACKGROUND: Surfactant protein (SP)-D is an epithelial cell product of the distal air spaces that aids uptake and clearance of inhaled pathogens and allergens. Allergic airway inflammation significantly increases SP-D levels in the bronchoalveolar lavage fluid in asthmatic patients and mouse models, but the mechanisms involved remain unknown. OBJECTIVE: To investigate the effects of the TH2-type cytokine IL-4 on SP-D production by isolated pulmonary epithelial cells. METHODS: Rat type II alveolar epithelial cells were purified and cultured with dexamethasone, cAMP, and isobutyl-1-methylxanthine (DCI). The effects of IL-4 on SP-D expression were investigated at the protein and mRNA levels by means of Western and Northern blot analyses. RESULTS: In contrast to a lamellar body protein ABCA3 and surfactant protein-A, expression of SP-D significantly declined when cells were cultured in medium alone for 24 hours. The presence of DCI in the culture medium restored SP-D levels, which were enhanced by 2-fold after addition of recombinant IL-4. The enhancing effects of IL-4 were concentration-dependent, with maximum effects observed at 20 ng/mL (1.43 nmol/L). IL-4 did not rescue cycloheximide-induced decrease of intracellular SP-D levels and did not inhibit extracellular release of SP-D. However, IL-4 significantly augmented DCI-induced SP-D mRNA expression by approximately 2.5-fold over control levels. CONCLUSIONS: IL-4 selectively upregulates SP-D expression, and it may act at the level of mRNA in isolated pulmonary epithelial cells. Since SP-D has a potent anti-inflammatory function, this mechanism may be part of a negative feedback loop providing a regulatory link between adaptive and innate immunity during allergic inflammation.
With the atomic force microscope (AFM), we preliminarily investigated the large-scale structure of actin filaments formed in low concentration protein solution (5 microg/ml) via self-organization without the presence of any F-actin dynamic interfering factors (such as phalloidin) in vitro. It was found that the G-actin could be polymerized into ordered filamentous structures with different diameter from the slimmest filament of single F-actin to giant filament in tree-like branched aggregates. The observed polymerized actin filaments, to which our most intense attention was attracted, was discretely distributed and showed obvious polymorphism distinctly different from those in the presence of phalloidin or actin binding proteins (fimbrin, gelsolin, etc.) in previous experiments. Latter structures were mainly composed of single F-actin and/or multifilaments clearly consisting of several single F-actin. The experimental results clearly demonstrated that non-interference with the F-actin intrinsic dynamics in self-organizing could lead to the polymorphism of actin filamentous structures, and further analysis implied that the disturbance of normal F-actin dynamics by many factors could prevent the emergence of structural polymorphism, more often than not, give rise to formation of specific structures instead and different interference would bring about various particular structures under certain conditions.
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OBJECTIVE: To analyze the relationship between traditional Chinese medical syndromes and fungal pneumonia for moderate and advanced lung cancer patients. METHODS: We retrospected 115 moderate and advanced lung cancer patients with different syndromes in traditional Chinese medicine (qi deficiency, yin deficiency, blood deficiency, yang deficiency, blood stasis, phlegm dampness, phlegm heat, damp heat, cold dampness, qi stagnation, heat toxin), who had the concurrent fungal pneumonia, and used regression analysis method to analyze the data. RESULTS: When the patients had the phlegm heat syndrome, they got a significantly higher risk of having fungal pneumonia (P < 0.01); and when they had the heat toxin syndrome, they also had a high risk of having fungal pneumonia (P < 0.05). CONCLUSION: The phlegm heat and heat toxin syndromes are the risk factors for moderate and advanced lung cancer patients having concurrent fungal pneumonia.
The authors examine the application of laparoscopy in the management of internal hemorrhage in tubal pregnancy in middle-sized and small hospitals. Altogether 76 such cases were collected for a review of the effects of laparoscopic management, and all were treated successfully without any complications. Laparoscopy causes minimal invasion in the management of internal hemorrhage in tubal pregnancy and may bring about rapid recovery of the patients, but the curative effects depend on the technical competence of the surgeon and the laparoscopic equipment.
OBJECTIVE: To investigate the effect of tranilast on transforming growth factor-beta(2) (TGF-beta(2)) expression in cultured human trabecular meshwork cells. METHODS: TGF-beta(2) expression in cultured 3-5 passage human trabecular meshwork cells was measured by semi-quantitative RT-PCR after treated with 0.0 micro g/ml (control), 12.5, 25.0 and 50.0 mg/L tranilast for 48 h. RESULTS: The value of TGF-beta(2)/G3PDH of cells treated with 12.5, 25.0 and 50.0 mg/L tranilast was 1.85 +/- 0.35, 1.66 +/- 0.42, 1.16 +/- 0.24, respectively. The difference between these treated groups and that of the control group (3.82 +/- 0.56) was statistically significant (q' = 10.77, 11.80, 14.54, P < 0.01), respectively. The value of TGF-beta(2)/G3PDH in the tranilast treated trabecular meshwork cells decreased in a dose-dependent manner. CONCLUSION: Tranilast could inhibit TGF-beta(2) expression in cultured human trabecular meshwork cells. It is worth to study the using of tranilast in the treatment of primary open-angle glaucoma.
OBJECTIVE: To observe the effect of radio frequency ablation (RFA) for treating metrorrhagia. METHOD: In-36 metrorrhagia patients, who failed to respond to both traditional Chinese medicine and western medicine, and who did not seek child-bearing with malignant changes of the uterus shown by gynecological examination, B-ultrasonic, diagnostic curettage, and pathological examination, the width and depth of the uterine cavity were measured while sending the coagulator to the bottom of the uterus, followed by coagulation of the uterine cavity for two times. The whole process was carried out under the supervision of B-ultrasonic, whose strong echo-band was between 0.8 and 1.0 cm. RESULT: Within one year, the effective rate was 100%, and no recurrence was found. CONCLUSION: RFA is easy, economical, safe and efficient in treating metrorrhagia.
Bone formation on hydroxyapatite (HA) coating in the presence of gaps is important for clinical application. Pure Ti and hydroxyapatite coated by plasma sprayed samples were implanted in dog respectively. The implants were surrounded by gaps of 2 mm, and the follow-up period was 12 weeks. Histological examination and histomorphometry revealed that gaps could be bridged by bone provided the hydroxyapatite coating was applied, and that pure Ti implants were surrounded by fibrous tissue with no bone contact at all.
OBJECTIVE: To explore the relationship between different left ventricular geometric patterns and ambulatory pulse pressures in essential hypertension patients. METHODS: Left ventricular geometric patterns were identified according to the results of left ventricular mass index and relative left ventricular thickness assessed by echocardiography in 130 hypertension patients. The average levels of 24-hour pulse pressure, daytime pulse pressure, and nighttime pulse pressure were analyzed by ambulatory blood pressure monitoring. The method of multiple stepwise regression analysis was applied to identify the independent determinants of ambulatory pulse pressures. After controlling or adjusting the effects of agr and the 24-hour mean arterial pressure, the average levels of 24-hour, daytime, and nighttime pulse pressure among different left ventricular geometric patterns were compared. Forty normotensive subjects served as controls. RESULTS: The age and the level of 24-hour mean arterial pressure were the independent determinants of 24-hour, daytime, and nighttime pulse pressure. After adjusting the effects of age and 24-hour mean arterial pressure, the average levels of 24-hour pulse pressure and daytime pulse pressure in concentric remodeling, concentric hypertrophy, and eccentric hypertrophy pattern groups were higher than those in the control group and normal geometric pattern group, whereas there were not significant differences among different left ventricular remodeling patterns at the average levels of 24-hour, daytime, and nighttime pulse pressure. CONCLUSION: Pulse pressure is an important risk factor in the development of cardiac remodeling in essential hypertension.
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Hyaluronic acid (HA) has been found to play important roles in tissue regeneration and wound-healing processes. Fetal tissue with a high concentration of HA heals rapidly without scarring. The present study employed HA formed into three-dimensional strands with or without keratinocytes to treat full-thickness skin incision wounds in rats. Wound closure rates of HA strand grafts both with and without keratinocytes were substantially enhanced. The closure times of both HA grafts were less than 1 day (average 16 h), about 1/7 that of the contralateral control incisions (114 h, p <.01). Average wound areas after 10 days were HA-only graft: 0.151 mm2 +/- 0.035; HA + cell grafts: 0.143 mm2 +/- 0.036 and controls: 14.434 mm2 +/- 1.175, experimental areas were 1% of the controls (p < 0.01). Transforming growth factor (TGF) beta1 measured by immunostaining was remarkably reduced in HA-treated wounds compared to the controls. In conclusion, HA grafts appeared to produce a fetal-like environment with reduced TGF-beta1, which is known to be elevated in incipient scars. The HA strands with or without cultured cells may potentially improve clinical wound healing as well as reduce scar formation.