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Biomedical subjects

Z Shen

Publications and source records attributed to Z Shen.

At least 19 recordsLinked to original sources
PubMed2006

Myofibroblast transdifferentiation in obliterative bronchiolitis: tgf-beta signaling through smad3-dependent and -independent pathways.

We have shown that Smad3, an intracellular signal transducer for transforming growth factor-beta1 (TGF-beta1), is required to elicit the full histological manifestations of obliterative airway disease in a tracheal transplant model. This suggests that chronic allograft rejection results in TGF-beta1-induced Smad3 activation that leads to airway obliteration through fibroproliferation and increased matrix deposition. In other systems, these latter events are causally related to the transdifferentiation of fibroblasts into myofibroblasts, but their role in obliterative bronchiolitis (OB) after lung transplantation is unknown. We confirmed the presence of myofibroblasts inside affected airways associated with experimental OB using immunohistochemistry. Studying airway fibroblasts in vitro, we observed increased myofibroblast transdifferentiation in response to TGF-beta1, evidenced by increased alpha-smooth muscle actin mRNA and protein expression. In Smad3-null fibroblasts, TGF-beta1 induction of myofibroblast transdifferentiation was greatly diminished but not abolished, suggesting the presence of Smad3-independent pathways. Further studies revealed that small molecule inhibitors of p38 (SB203580) and MEK/ERK (U1026) further reduced the remaining effect of TGF-beta1 in Smad3-deficient fibroblasts. Together, these studies suggest that in chronic allograft rejection, TGF-beta1 stimulates myofibroblast transdifferentiation through Smad3-dependent and -independent signals, contributing to the excessive matrix deposition that characterizes obliterative bronchiolitis.

Actins↗
PubMed2006

Fascin is a potential biomarker for early-stage oesophageal squamous cell carcinoma.

BACKGROUND: Fascin, an actin-binding protein, is usually expressed at a low level in normal epithelium, but is markedly up regulated in several types of carcinomas. Reports on fascin expression in oesophageal squamous cell carcinoma (ESCC) and precancerous lesions remain rare. AIM: To show the roles of fascin in the progression from normal epithelium to invasive ESCC. METHODS: Fascin expression in 102 sections embedded in paraffin wax, including samples of normal mucosa (n = 20), dysplasia (n = 10), ESCC (n = 62) and special sections (n = 10) of a full-length mucosa layer from the distant margin to the cancer focus of the excised oesophagus, and 49 fresh specimens of ESCC was analysed by immunohistochemistry, western blot and real-time reverse transcription-polymerase chain reaction. Fascin expression in ESCC cell lines was also investigated. RESULTS: In the immunohistochemical study, the positive rate of fascin was significantly higher in the tumour tissue than in the normal epithelium (p = 0.020), but no significant difference was shown between ESCC and dysplasia (p = 1.000). Immunostaining for fascin was only apparent in the basal layer of the normal epithelium. However, in the dysplasia, positive staining was observed in most of the heterogeneous cells from the basal layer to the granular layer of the epithelium. Fascin expression was seen to increase progressively from the normal epithelium to invasive ESCC. Up regulation of fascin was observed in 87.76% (43/49) and 77.55% (38/49) of the specimens, respectively, using western blot and real-time reverse transcription-polymerase chain reaction assays; 80% (4/5) of ESCC cell lines also expressed fascin at a high level. Furthermore, overexpression of fascin was markedly correlated with cell proliferation and lymph node metastasis. CONCLUSIONS: These findings suggested that fascin was associated with the transformation and development of ESCC and implicated the potential of fascin as a novel biomarker that would allow the tumour to be identified at an early stage in high-risk individuals.

Adult↗
PubMed2006

Transport of acetate and sodium in sheep omasum: mutual, but asymmetric interactions.

We have studied the transport of acetate across the isolated epithelium of sheep omasum; no net transport was observed (J(ms) approximately = J(sm)) under Ussing chamber conditions. Low mucosal pH (pH 6.4) significantly enhanced J(ms) acetate and the transport rates of acetate increased linearly and significantly (r2=0.99) with the luminal acetate concentration. The presence of another short chain fatty acid (propionate) did not affect J(ms) acetate significantly. Neither addition of 1 mmol l(-1) DIDS to the mucosal side nor HCO3 replacement caused changes of J(ms) acetate; this does not support the assumption of acetate transport via anion exchange. Addition of 1 mmol l(-1) amiloride to the mucosal side significantly decreased acetate fluxes at high mucosal acetate concentration (100 mmol l(-1)) and low pH (6.4) indicating interaction between acetate uptake in the undissociated form, intracellular release of protons and activation of Na+/H+ exchange (NHE). However, the mutual interaction between Na transport via NHE and acetate transport is asymmetric. Stimulation or inhibition of Na transport via NHE is much more pronounced than the corresponding changes of acetate fluxes. Thus, the obtained results support the conclusion that acetate is transported via simple diffusion and probably predominantly in the protonated form, thereby explaining the positive and mutual interaction between Na transport and short chain fatty acids.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2005

Storage and secretion of Ag-Aper14, a novel peritrophic matrix protein, and Ag-Muc1 from the mosquito Anopheles gambiae.

The gene Ag-Aper14 encodes a novel peritrophic matrix (or peritrophic membrane; PM) protein in the mosquito Anopheles gambiae. The Ag-Aper14 protein is merely 89 amino acids long and has a single putative chitin-binding domain. Prior to blood feeding, the Ag-Aper14 protein is stored in secretory vesicles next to the epithelial cell lumenal surface. Immunoelectron microscopy has revealed that Ag-Aper14 co-localizes to the same secretory vesicles as another PM protein, Ag-Aper1, indicating a common mode of regulated secretion. Conversely, Ag-Muc1, an epithelial cell-surface protein, does not co-localize to these secretory vesicles and is detected only on the cell surface. After blood feeding, Ag-Aper14 is secreted and incorporated into the PM that surrounds the ingested blood.

Amino Acid Sequence↗
PubMed2005

HLA DR B1*04, *07-restricted epitopes on Keratin 17 for autoreactive T cells in psoriasis.

BACKGROUND: Psoriasis is a T cell-mediated inflammatory skin disease. Recent evidence suggests that activated CD4+ helper T lymphocytes of the Th1 phenotype play an important role in the pathogenesis of the disease. For psoriatic autoreactive T cells, Keratin 17 is a major target antigen and an epitope containing ALEEAN sequence has been described, but other psoriasis-related epitopes are still unknown. OBJECTIVE: To identify the HLA DR B1*04, *07-restricted T cell epitopes on Keratin 17. METHODS: HLA DRB1*04, *07-restricted T cell epitope regions on Keratin 17 were predicted based on related software and internet servers. Keratin 17 gene was amplified from psoriatic epidermis and the proteins of the predicted epitope regions were expressed, identified and purified. T cells from psoriatic patients reacted in cultivation with peptide-major histocompatibility complex (p-MHC) compound, then the level of cell proliferation and the concentration of interferon-gamma in culture supernatant were detected. After the psoriasis-related epitope regions were narrowed down, the epitopes on them were predicted further. These epitopes were then expressed and validated by T cell response in vitro. RESULTS: Four epitopes--S1 (118-132), S2 (169-183), S4 (323-337) and S4 (348-362) can stimulate the proliferation and interferon-gamma production of psoriatic T cells more effectively than other epitopes (p<0.01) and react weakly with the T cells from healthy volunteers (p>0.05). CONCLUSION: Epitopes S1 (118-132), S2 (169-183), S4 (323-337) and S4 (348-362) are immunodominant DR B1-restricted T cell epitopes for psoriasis. Among them, S1 (118-132) contains the ALEEAN sequence while the others with different amino acid sequence have not been reported before. Further studies based on these peptides would provide a more complete understanding of the immunological basis of psoriasis.

Amino Acid Sequence↗
PubMed2005

Inhibition of the calcium- and voltage-dependent big conductance potassium channel ameliorates cisplatin-induced apoptosis in spiral ligament fibrocytes of the cochlea.

The role of calcium- and voltage-dependent big conductance potassium channels in regulating apoptosis was investigated in cultured type I spiral ligament fibrocytes. Incubation of type I spiral ligament fibrocytes derived from gerbil cochlea with cisplatin induced dose- and time-dependent apoptosis as demonstrated by annexin V conjugated to fluorescein isothiocyanate/prodidium iodide assays. The average voltage activation threshold of whole cell current was sharply shifted to -40 mV in the cisplatin-treated cells as compared with a value of 40 mV in control cells. The average whole-cell current of cisplatin-treated cells induced by a depolarization voltage step from -80 to -10 mV was increased significantly to 1.2+/-0.4 nA as compared with 0.08+/-0.1 nA in control cells. Coincubation with tetraethylammonium and cisplatin retained the whole cell current in the normal range (0.12+/-0.2 nA). The increment of cisplatin-induced whole-cell current was inhibited (97+/-5%) by a specific calcium- and voltage-dependent big conductance potassium channel blocker iberiotoxin. Consistent with this, co-incubation with tetraethylammonium significantly attenuated cisplatin-induced apoptosis in type I spiral ligament fibrocytes by more than 50%. We conclude that the activation of BK channels is an early event associated with cisplatin-induced apoptosis in type I spiral ligament fibrocytes. These findings also point to the calcium- and voltage-dependent big conductance potassium channels as a potential pharmacological target for manipulating cisplatin ototoxicity.

Animals↗
PubMed2004

Orexigenic action of peripheral ghrelin is mediated by neuropeptide Y and agouti-related protein.

Ghrelin, a stomach-derived orexigenic hormone, has stimulated great interest as a potential target for obesity control. Pharmacological evidence indicates that ghrelin's effects on food intake are mediated by neuropeptide Y (NPY) and agouti-related protein (AgRP) in the central nervous system. These include intracerebroventricular application of antibodies to neutralize NPY and AgRP, and the application of an NPY Y1 receptor antagonist, which blocks some of the orexigenic effects of ghrelin. Here we describe treatment of Agrp(-/-);Npy(-/-) and Mc3r(-/-);Mc4r(-/-) double knockout mice as well as Npy(-/-) and Agrp(-/-) single knockout mice with either ghrelin or an orally active nonpeptide ghrelin agonist. The data demonstrate that NPY and AgRP are required for the orexigenic effects of ghrelin, as well as the involvement of the melanocortin pathway in ghrelin signaling. Our results outline a functional interaction between the NPY and AgRP pathways. Although deletion of either NPY or AgRP caused only a modest or nondetectable effect, ablation of both ligands completely abolished the orexigenic action of ghrelin. Our results establish an in vivo orexigenic function for NPY and AgRP, mediating the effect of ghrelin.

Agouti-Related Protein↗
PubMed2004

Pool of dust particles over the Asian continent: balloon-borne optical particle counter and ground-based lidar measurements at Dunhuang, China.

Measurements of aerosols were made in 2001 and 2002 at Dunhuang (40 degrees 00'N, 94 degrees 30'E), China to understand the nature of atmospheric particles over the desert areas in the Asian continent. Balloon-borne measurements with an optical particle counter suggested that particle size and concentration had noticeable peaks in super micron size range not only in the boundary mixing layer but also in the free troposphere. Super-micron particle concentration largely decreased in the mid tropopause (from 5 to 10 km; above sea level, a.s.l.). Lidar measurements made during August 2002 at Dunhuang suggested the possibility that mixing of dust particles occurred from near the ground to about 6 km even under calm weather conditions, and a large depolarization ratio of particulate matter was found in the aerosol layer. The top of the aerosol layer was found at heights of nearly 6 km (a.s.l.). It is strongly suggested that nonspherical dust particles (Kosa particles) frequently diffused in the free atmosphere over the Taklamakan desert through small-scale turbulences and are possible sources of dust particles of weak Kosa events that have been identified in the free troposphere not only in spring but also in summer over Japanese archipelago. Electron microscopic experiments of the particles collected in the free troposphere confirmed that coarse and nonspherical particles observed by the mineral particle were major components of coarse mode (diameter larger than 1 microm) below about 5 km over Dunhuang, China.

Aerosols↗
PubMed2004

Differences in the metabolism and pharmacokinetics of two structurally similar PPAR agonists in dogs: involvement of taurine conjugation.

1. The metabolism and pharmacokinetics of two structurally similar PPAR agonists, MRL-I, (2R)-7-[3-[2-chloro-4-(4-fluorophenoxy)phenoxy]propoxy]-2-ethyl-3,4-dihydro-2H-benzopyran-2-carboxylic acid, and MRL-II, (2R)-7-[3-[2-chloro-4-(2,2,2,-trifluoroethoxy)phenoxy]propoxy]-3,4-dihydro-2-methyl-2H-benzopyran-2-carboxylic acid, in dogs were investigated. 2. MRL-I was absorbed rapidly in dogs and exhibited linear pharmacokinetics over the dose range examined, 1-25mgkg(-1). In contrast, the pharmacokinetics of MRL-II were non-linear following both intravenous and oral administration. 3. The acyl glucuronide (AG) conjugate was the only radioactive component detected in bile from dogs dosed with [14C]MRL-I, whereas bile from dogs dosed with [14C]MRL-II contained varying amounts of both the AG and taurine conjugates. The percentages of the acyl glucuronide and taurine conjugates of [14C]MRL-II in dog bile were dose dependent. A higher percentage of radioactivity was associated with the taurine conjugate (about 41%) following intravenous administration at 0.2mgkg(-1) than at 0.9mgkg(-1) (about 14%) or oral administration at 5 mgkg(-1) (about 6%). The decrease in the percentage of radioactivity associated with the taurine conjugate at 0.9 mgkg(-1) was accompanied by a concomitant increase in the amount of the acyl glucuronide. 4. MRL-I, but not MRL-II, was subject to significant enterohepatic recirculation in dogs. Continuous collection of bile resulted in an 11-fold decrease in the terminal half-life of MRL-I in plasma (1.5 versus 16.6 h), and a 2.4-fold increase in its plasma clearance (4.0 versus 1.7 ml min(-1) kg(-1)) after intravenous administration at 1 mg kg(-1). 5. Collectively, the data suggest that the presence and subsequent saturation of the taurine conjugation pathway might have contributed to the non-linear pharmacokinetics of MRL-II in the dog.

Administration, Oral↗
PubMed2004

The effect of antisense tyrosinase-related protein 1 on melanocytes and malignant melanoma cells.

BACKGROUND: Tyrosinase-related proteins (TRPs) include tyrosinase, TRP-1 and TRP-2. The functions of tyrosinase and TRP-2 have been determined, but the biological role of TRP-1 is still controversial and is not well known in humans. OBJECTIVES: To study further the biological role of the human TRP-1 gene in melanocytes and melanoma cells. METHODS: TRP-1 cDNA was subcloned into eukaryotic expression vector pcDNA3.1 in the reverse direction, and antisense recombinant vector was transfected into melanocytes and a melanoma cell line using Lipofectamine 2000. Positive cells were selected by geneticin. TRP-1 mRNA level was measured by reverse transcription-polymerase chain reaction (RT-PCR), and TRP-1 protein level by Western blot. Cell cycles were determined by flow cytometry, and the activity of tyrosinase was evaluated by L-DOPA reaction. Light microscopy, electron microscopy and flow cytometry were used to observe cell morphology and apoptosis. For in vivo assays, the antitumour activity of antisense TRP-1 against the malignant melanoma (MM) cell line, Libr, was evaluated in an animal-tumour model of subcutaneous tumours. RESULTS: Positive transfected cells steadily expressed TRP-1 antisense RNA. RT-PCR and Western blot showed a low level of TRP-1 mRNA and TRP-1 protein, respectively. Cell cycles were blocked in the G1 stage, and the activity of tyrosinase decreased significantly (P < 0.01). Light and electron microscopy showed abnormal cell morphology, and apoptosis was detected. The neoplasia activity of antisense TRP-1-transfected MM cells was significantly lower than that of MM cells (P < 0.01). CONCLUSIONS: TRP-1 plays an important role in the proliferation, morphology and tyrosinase activity of melanocytes and melanoma cells.

Animals↗
PubMed2004

Radiation synovectomy by 188Re-Sulfide in haemophilic synovitis.

Radiation synovectomy is a safe and effective treatment for chronic haemophilic synovitis causing recurrent haemarthroses. This study reports results of 29 188Re-sulfide radiation synovectomies in knee joint with a follow-up 18 months. Using the absorbed dose factor, three groups of radioactivity dose (555 MBq, 687 MBq and 917 MBq) were used according to the synovium thickness that measured by MRI. Excellent and good results (haemarthrosis reduction from 75 to 100%) were obtained in 71% of cases at 18 months. Comparison of the results, no significant difference was found among the radioactivity dose groups. Radiation was well contained within the knee. There were no observed or identified complications including the detectable harm to the articular cartilage, as shown by MRI.

Adult↗
PubMed2003

A voltage- and Ca2+-dependent big conductance K channel in cochlear spiral ligament fibrocytes.

Evidence is accruing that spiral ligament fibrocytes (SLFs) play an important role in cochlear K(+) homeostasis, but little direct physiological data is available to support this concept. Here we report the presence and characterization of a voltage- and Ca(2+)-dependent big-conductance K (BK) channel in type I SLFs cultured from the gerbil cochlea. A single-channel conductance of 298+/-5.6 pS (n=28) was measured under symmetrical K(+). Membrane potentials for half-maximal open probability (P(o)) were -67, -45 and 85 mV with cytosolic free-Ca(2+) levels of 0.7 mM, 10 microM and 1 microM, respectively (n=8-14). The Hill coefficient for Ca(2+) affinity was 1.9 at a membrane potential of 60 mV (n=6). The BK channel showed very low activity (P(o)=0.0019, n=5) under normal physiological conditions, suggesting a low resting intracellular free [Ca(2+)]. Pharmacological results fit well with the profile of classic BK channels. The estimated half-maximal inhibitory concentration and Hill coefficient for tetraethylammonium were 0.086+/-0.021 mM and 0.99, respectively (n=4-9). In whole cell recordings, the voltage-activated outward K current was inhibited 85.7+/-4.5% (n=6) by 0.1 microM iberiotoxin. A steady-state kinetic model with two open and two closed stages best described the BK gating process (tau(o1) 0.23+/-0.08 ms, tau(o2) 1.40+/-0.32 ms; tau(c1) 0.26+/-0.09 ms, tau(c2) 3.10+/-1.2 ms; n=11). RT-PCR analyses revealed a splice variant of the BK channel alpha subunit in cultured type I SLFs and freshly isolated spiral ligament tissues. The BK channel is likely to play a major role in regulating the membrane potential of type I SLFs, which may in turn influence K(+) recycling dynamics in the mammalian cochlea.

Animals↗
PubMed2003

Identification of novel metabolites of pioglitazone in rat and dog.

1. Four new metabolites of pioglitazone were identified by liquid chromatography-mass spectrometry (LC-MS/MS) as being formed by hydroxylation (M-VII and M-VIII), opening of the thiazolidinedione ring (M-X) and by desaturation of the terminal ethyl side chain or tether ethoxy moiety (M-IX), respectively. The structure of one of the hydroxylated metabolites (M-VII) was confirmed by chemical modification using the Jones reaction. 2. Oxidative cleavage of the thiazolidinedione ring is a novel pathway not previously reported for pioglitazone. 3. The hydroxylated M-VII was detected in incubations with rat, dog and human liver and kidney microsomes, and in plasma from rats and dogs dosed orally with [(3)H]pioglitazone. 4. The carboxylic acid derivative of M-VII (M-V) and its taurine conjugate were the major radioactive components in dog bile.

Animals↗
PubMed2002

Alpha-glucosidase inhibition from a Chinese medical herb (Ramulus mori) in normal and diabetic rats and mice.

Alpha-glucosidase inhibitors are oral antidiabetic drugs. A traditional Chinese medical herb, Sangzhi (Ramulus mori), appears to have properties similar to those of alpha-glucosidase inhibitors. The effects of an aqueous extract of Shangzhi (SZ) were studied in normal and alloxan diabetic rats and mice, and these results compared with those for acarbose, an alpha-glucosidase inhibitor. In our grade-dose studies, SZ was found to lower and prolong the zenith of blood glucose concentration (ZBG) after sucrose or starch loading and stabilize blood glucose levels in fasting normal and alloxan diabetic mice. After 2 weeks of SZ administration with high-calorie chow or a normal diet, the fasting and non-fasting blood glucose concentrations in alloxan diabetic mice and rats were decreased. In alloxan rats, the blood fructosamine concentration was lowered. Results for acarbose and SZ were similar. These indicate that SZ has alpha-glucosidase inhibitory effects.

Alloxan↗
PubMed2002

Multiple transcription factor profiling by enzyme-linked immunoassay.

Transcription factor-DNA interactions have been widely studied in the regulation of gene expression. We have established an enzyme-linked immunoassay platform to quantify specific transcriptionfactor-DNA interactions. In our assay, dsDNA immobilized on a 96-well plate captures the transcriptionfactor from the nuclear extract of mammalian cells. The DNA-bound transcription factor is detected and quantified by enzyme-linked immunoassay using a transcription factor-specific antibody. We have profiled multiple transcription factors involved in inflammation including NFkappaB p50, NFkappaB p65, c-Rel, c-Fos, CREB-1, and ATF-2. When compared with the traditional electrophoretic mobility shift assay, the enzyme-linked immunoassay shows a 10-fold higher sensitivity, eliminates the use of radioactivity, allows for a high-throughput format, and is faster.

Activating Transcription Factor 2↗
PubMed2001

Overexpression of human RAD51 and RAD52 reduces double-strand break-induced homologous recombination in mammalian cells.

Double-strand breaks (DSBs) can be repaired by homologous recombination (HR) in mammalian cells, often resulting in gene conversion. RAD51 functions with RAD52 and other proteins to effect strand exchange during HR, forming heteroduplex DNA (hDNA) that is resolved by mismatch repair to yield a gene conversion tract. In mammalian cells RAD51 and RAD52 overexpression increase the frequency of spontaneous HR, and one study indicated that overexpression of mouse RAD51 enhances DSB-induced HR in Chinese hamster ovary (CHO) cells. We tested the effects of transient and stable overexpression of human RAD51 and/or human RAD52 on DSB-induced HR in CHO cells and in human cells. DSBs were targeted to chromosomal recombination substrates with I-SceI nuclease. In all cases, excess RAD51 and/or RAD52 reduced DSB-induced HR, contrasting with prior studies. These distinct results may reflect differences in recombination substrate structures or different levels of overexpression. Excess RAD51/RAD52 did not increase conversion tract lengths, nor were product spectra otherwise altered, indicating that excess HR proteins can have dominant negative effects on HR initiation, but do not affect later steps such as hDNA formation, mismatch repair or the resolution of intermediates.

Animals↗
PubMed2001

Interaction with BRCA2 suggests a role for filamin-1 (hsFLNa) in DNA damage response.

The BRCA2 tumor suppressor plays significant roles in DNA damage response. The human actin binding protein filamin-1 (hsFLNa, also known as ABP-280) participates in orthogonal actin network, cellular stress responses, signal transduction, and cell migration. Through a yeast two-hybrid system, an in vitro binding assay, and in vivo co-immunoprecipitations, we identified an interaction between BRCA2 and hsFLNa. The hsFLNa binding domain of BRCA2 was mapped to an internal conserved region, and the BRCA2-interacting domain of hsFLNa was mapped to its C terminus. Although hsFLNa is known for its cytoplasmic functions in cell migration and signal transduction, some hsFLNa resides in the nucleus, raising the possibility that it participates in DNA damage response through a nuclear interaction with BRCA2. Lack of hsFLNa renders a human melanoma cell line (M2) more sensitive to several genotoxic agents including gamma irradiation, bleomycin, and ultraviolet-c light. These results suggest that BRCA2/hsFLNa interaction may serve to connect cytoskeletal signal transduction to DNA damage response pathways.

BRCA2 Protein↗