Biomedical subjects

Jin Yu

Publications and source records attributed to Jin Yu.

At least 19 recordsLinked to original sources

PubMed2007

Estradiol enhances neurogenesis following ischemic stroke through estrogen receptors alpha and beta.

Neurogenesis persists throughout life under normal and degenerative conditions. The adult subventricular zone (SVZ) generates neural stem cells capable of differentiating to neuroblasts and migrating to the site of injury in response to brain insults. In the present study, we investigated whether estradiol increases neurogenesis in the SVZ in an animal model of stroke to potentially promote the ability of the brain to undergo repair. Ovariectomized C57BL/6J mice were implanted with capsules containing either vehicle or 17beta-estradiol, and 1 week later they underwent experimental ischemia. We utilized double-label immunocytochemistry to identify the phenotype of newborn cells (5-bromo-2'-deoxyuridine-labeled) with various cellular markers; doublecortin and PSA-NCAM as the early neuronal marker, NeuN to identify mature neurons, and glial fibrillary acidic protein to identify astrocytes. We report that low physiological levels of estradiol treatment, which exert no effect in the uninjured state, significantly increase the number of newborn neurons in the SVZ following stroke injury. This effect of estradiol is limited to the dorsal region of the SVZ and is absent from the ventral SVZ. The proliferative actions of estradiol are confined to neuronal precursors and do not influence gliosis. Furthermore, we show that both estrogen receptors alpha and beta play pivotal functional roles, insofar as knocking out either of these receptors blocks the ability of estradiol to increase neurogenesis. These findings clearly demonstrate that estradiol stimulates neurogenesis in the adult SVZ, thus potentially facilitating the brain to remodel and repair after injury.

Animals↗

PubMed2007

Molecular basis for calcium signaling in hepatic stellate cells.

Progressive liver fibrosis (with the resultant cirrhosis) is the primary cause of chronic liver failure. Hepatic stellate cells (HSCs) are critically important mediators of liver fibrosis. In the healthy liver, HSCs are quiescent lipid-storing cells limited to the perisinusoidal endothelium. However, in the injured liver, HSCs undergo myofibroblastic transdifferentiation (activation), which is a critical step in the development of organ fibrosis. HSCs express P2Y receptors linking extracellular ATP to inositol (1,4,5)-trisphosphate-mediated cytosolic Ca(2+) signals. Here, we report that HSCs express only the type I inositol (1,4,5)-trisphosphate receptor and that the receptor shifts into the nucleus and cell extensions upon activation. These cell extensions, furthermore, express sufficient machinery to enable local application of ATP to evoke highly localized Ca(2+) signals that induce localized contractions. These autonomous units of subcellular signaling and response reveal a new level of subcellular organization, which, in turn, establishes a novel paradigm for the local control of fibrogenesis in the liver.

Active Transport, Cell Nucleus↗

PubMed2006

Identification of a complement receptor 1 peptide for inhibition of immune hemolysis.

Complement sensitization of red blood cells (RBCs) can cause life-threatening hemolytic anemias. We have previously shown that complement receptor 1 (CR1) derivatives specifically the N-terminal region with decay accelerating activity (DAA) for inactivation of a key enzyme in the complement cascade can reduce complement-mediated RBC destruction in vitro and in an in vivo mouse model of hemolytic transfusion reaction. In the present study, we have modeled the N-terminal CR1 molecule based on the X-ray crystal structure of decay accelerating factor and the NMR structure of a homologous CR1 domain. Based on the homology model, we identified a 34-mer peptide encompassing the putative DAA which in vitro reduced hemolysis, C3a release and surface C3 deposition. More importantly, this peptide at 0.6 mM was effective in prolonging survival of transfused incompatible RBCs in vivo. Our results indicate that CR1-based structure-function studies may provide insights for developing structure-derived transfusion therapeutics in the future.

Amino Acid Sequence↗

PubMed2006

Complement-dependent P-selectin expression and injury following ischemic stroke.

The mechanisms that contribute to inflammatory damage following ischemic stroke are poorly characterized, but studies indicate a role for both complement and P-selectin. In this study, we show that compared with wild-type mice, C3-deficient mice showed significant improvement in survival, neurological deficit, and infarct size at 24 h after middle cerebral artery occlusion and reperfusion. Furthermore, P-selectin protein expression was undetectable in the cerebral microvasculature of C3-deficient mice following reperfusion, and there was reduced neutrophil influx, reduced microthrombus formation, and increased blood flow postreperfusion in C3-deficient mice. We further investigated the use of a novel complement inhibitory protein in a therapeutic paradigm. Complement receptor 2 (CR2)-Crry inhibits complement activation at the C3 stage and targets to sites of complement activation. Treatment of normal mice with CR2-Crry at 30 min postreperfusion resulted in a similar level of protection to that seen in C3-deficient mice in all of the above-measured parameters. The data demonstrate an important role for complement in cerebrovascular thrombosis, inflammation, and injury following ischemic stroke. P-selectin expression in the cerebrovasculature, which is also implicated in cerebral ischemia and reperfusion injury, was shown to be distal to and dependent on complement activation. Data also show that a CR2-targeted approach of complement inhibition provides appropriate bioavailability in cerebral injury to enable complement inhibition at a dose that does not significantly affect systemic levels of serum complement activity, a potential benefit for stroke patients where immunosuppression would be undesirable due to significantly increased susceptibility to lung infection.

Animals↗

PubMed2006

The key role of chlorocatechol 1,2-dioxygenase in phytoremoval and degradation of catechol by transgenic Arabidopsis.

Transgenic exploitation of bacterial degradative genes in plants has been considered a favorable strategy for degrading organic pollutants in the environment. The aromatic ring characteristic of these pollutants is mainly responsible for their recalcitrance to degradation. In this study, a Plesiomonas-derived chlorocatechol 1,2-dioxygenase (TfdC) gene (tfdC), capable of cleaving the aromatic ring, was introduced into Arabidopsis (Arabidopsis thaliana). Morphology and growth of transgenic plants are indistinguishable from those of wild-type plants. In contrast, they show significantly enhanced tolerances to catechol. Transgenic plants also exhibit strikingly higher capabilities of removing catechol from their media and high efficiencies of converting catechol to cis,cis-muconic acid. As far-less-than-calculated amounts of cis,cis-muconic acid were accumulated within the transgenic plants, existence of endogenous TfdD- and TfdE-like activities was postulated and, subsequently, putative orthologs of bacterial tfdD and tfdE were detected in Arabidopsis. However, no TfdC activity and no putative orthologs of either tfdC or tfdF were identified. This work indicates that the TfdC activity, conferred by tfdC in transgenic Arabidopsis, is a key requirement for phytoremoval and degradation of catechol, and also suggests that microbial degradative genes may be transgenically exploited in plants for bioremediation of aromatic pollutants in the environment.

Arabidopsis↗

PubMed2006

Structure-based model of the stepping motor of PcrA helicase.

DNA helicases are ubiquitous molecular motors involved in cellular DNA metabolism. They move along single-stranded DNA (ssDNA) and separate duplex DNA into its component strands, utilizing the free energy from ATP hydrolysis. The PcrA helicase from Bacillus stearothermophilus translocates as a monomer progressively from the 3' end to the 5' end of ssDNA and is one of the smallest motor proteins structurally known in full atomic detail. Using high-resolution crystal structures of the PcrA-DNA complex, we performed nanosecond molecular dynamics simulations and derived potential energy profiles governing individual domain movement of the PcrA helicase along ssDNA. Based on these profiles, the millisecond translocation of the helicase along ssDNA was described through Langevin dynamics. The calculations support a domain stepping mechanism of PcrA helicase, in which, during one ATP hydrolysis cycle, the pulling together and pushing apart of domains 2A and 1A are synchronized with alternating mobilities of the individual domains in such a fashion that PcrA moves unidirectionally along ssDNA. By combining short timescale (nanoseconds) molecular dynamics and long timescale (milliseconds) stochastic-dynamics descriptions, our study suggests a structure-based mechanism of the ATP-powered unidirectional movement of PcrA helicase.

Adenosine Triphosphate↗

PubMed2006

A rat model of bone cancer pain induced by intra-tibia inoculation of Walker 256 mammary gland carcinoma cells.

This study described a modified rat model of bone cancer pain. Syngeneic Walker 256 mammary gland carcinoma cells were injected into the tibia medullary cavity via intercondylar eminence. Series of tests were carried out including bone radiology, bone histology, ambulatory pain, thermal hyperalgesia, mechanical allodynia, weight bearing ability, and electrophysiological recording from primary afferent fibers. The rats inoculated with carcinoma cells showed significant ambulatory pain, mechanical allodynia, and reduction in weight bearing, as well as increased incidence of spontaneous activity in Abeta fibers in affected limb, whereas PBS (vehicle) or heat-killed cells (sham) injected rats showed no significant difference in comparison to normal rats. The pain hypersensitive behaviors were aggravated with time and destruction of bone. Interestingly, mechanical allodynia was also observed in the contralateral limb, indicating the involvement of 'mirror image' pain in bone cancer pain. In summary, the present study provided a useful and easily established rat model of bone cancer pain which will contribute to further study of the mechanisms underlying cancer pain.

Action Potentials↗

PubMed2006

p204 is required for the differentiation of P19 murine embryonal carcinoma cells to beating cardiac myocytes: its expression is activated by the cardiac Gata4, Nkx2.5, and Tbx5 proteins.

Among 10 adult mouse tissues tested, the p204 protein levels were highest in heart and skeletal muscle. We described previously that the MyoD-inducible p204 protein is required for the differentiation of cultured murine C2C12 skeletal muscle myoblasts to myotubes. Here we report that p204 was also required for the differentiation of cultured P19 murine embryonal carcinoma stem cells to beating cardiac myocytes. As shown by others, this process can be triggered by dimethyl sulfoxide (DMSO). We established that DMSO induced the formation of 204RNA and p204. Ectopic p204 could partially substitute for DMSO in inducing differentiation, whereas ectopic 204 antisense RNA inhibited the differentiation. Experiments with reporter constructs, including regulatory regions from the Ifi204 gene (encoding p204) in P19 cells and in cultured newborn rat cardiac myocytes, as well as chromatin coimmunoprecipitations with transcription factors, revealed that p204 expression was synergistically transactivated by the cardiac Gata4, Nkx2.5, and Tbx5 transcription factors. Furthermore, ectopic p204 triggered the expression of Gata4 and Nkx2.5 in P19 cells. p204 contains a nuclear export signal and was partially translocated to the cytoplasm during the differentiation. p204 from which the nuclear export signal was deleted was not translocated, and it did not induce differentiation. The various mechanisms by which p204 promoted the differentiation are reported in the accompanying article (Ding, B., Liu, C., Huang, Y., Yu, J., Kong, W., and Lengyel, P. (2006) J. Biol. Chem. 281, 14893-14906).

Amino Acid Sequence↗

PubMed2006

p204 protein overcomes the inhibition of the differentiation of P19 murine embryonal carcinoma cells to beating cardiac myocytes by Id proteins.

We reported in the accompanying article (Ding, B., Liu, C., Huang, Y., Hickey, R. P., Yu, J., Kong, W., and Lengyel, P. (2006) J. Biol. Chem. 281, 14882-14892) that (i) the p204 protein is required for the differentiation of murine P19 embryonal carcinoma stem cells to beating cardiac myocytes, and (ii) the expression of p204 in the differentiating P19 cells is synergistically transactivated by the cardiac transcription factors Gata4, Nkx2.5, and Tbx5. Here we report that endogenous or ectopic inhibitor of differentiation (Id) proteins inhibited the differentiation of P19 cells to myocytes. This was in consequence of the binding of Id1, Id2, or Id3 protein to the Gata4 and Nkx2.5 proteins and the resulting inhibitions (i) of the binding of these transcription factors to each other and to DNA and (ii) of their synergistic transactivation of the expression of various genes, including atrial natriuretic factor and Ifi204 (encoding p204). p204 overcame this inhibition by Id proteins in consequence of (i) binding and sequestering Id proteins, (ii) accelerating their ubiquitination and degradation by proteasomes, and (iii) decreasing the level of Id proteins in the nucleus by increasing their translocation from the nucleus to the cytoplasm. Points (ii) and (iii) depended on the presence of the nuclear export signal in p204. In the course of the differentiation, Gata4, Nkx2.5, and p204 were components of a positive feedback loop. This loop arose in consequence of it that p204 overcame the inhibition of the synergistic activity of Gata4 and Nkx2.5 by the Id proteins.

Animals↗

PubMed2006

Differential modulation of estrogen receptors (ERs) in ischemic brain injury: a role for ERalpha in estradiol-mediated protection against delayed cell death.

Estradiol enhances plasticity and survival of the injured brain. Our previous work demonstrates that physiological levels of estradiol protect against cerebral ischemia in the young and aging brain through actions involving estrogen receptors (ERs) and alterations in gene expression. The major goal of this study was to establish mechanisms of neuroprotective actions induced by low levels of estradiol. We first examined effects of estradiol on the time-dependent evolution of ischemic brain injury. Because estradiol is known to influence apoptosis, we hypothesized that it acts to decrease the delayed phase of cell death observed after middle cerebral artery occlusion (MCAO). Furthermore, because ERs are pivotal to neuroprotection, we examined the temporal expression profiles of both ER subtypes, ERalpha and ERbeta, after MCAO and delineated potential roles for each receptor in estradiol-mediated neuroprotection. We quantified cell death in brains at various times after MCAO and analyzed ER expression by RT-PCR, in situ hybridization, and immunohistochemistry. We found that during the first 24 h, the mechanisms of estradiol-induced neuroprotection after MCAO are limited to attenuation of delayed cell death and do not influence immediate cell death. Furthermore, we discovered that ERs exhibit distinctly divergent profiles of expression over the evolution of injury, with ERalpha induction occurring early and ERbeta modulation occurring later. Finally, we provide evidence for a new and functional role for ERalpha in estradiol-mediated protection of the injured brain. These findings indicate that physiological levels of estradiol protect against delayed cell death after stroke-like injury through mechanisms requiring ERalpha.

Animals↗

PubMed2006

Bulge cells of human hair follicles: segregation, cultivation and properties.

The bulge region of hair follicle has been reported as a putative reservoir of hair follicle stem cell (HFSC) for years; however, few studies were done about the characteristics of bulge-originated cells in vitro up to now. In this experiment, the bulge cells isolated from human hair follicles by enzymatic digestion and microdissection were cultured and passaged, and the morphological and biological features of cultured bulge cells were investigated by microscopy and immunocytochemistry. The result showed that new-proliferated cells could be observed on the second day after inoculation, and the quantity of the cells with a greater proliferation potential, reached a peak at the 6th day and maintained this higher level for several days. The mitotic figures of bulge cells were seen and these cells showed undifferentiated morphologic features. The bulge cells strongly expressed K19 and beta1-integrin, which are the markers of HFSC, in a descensive way with the culture time. The result indicates that the cultured bulge cell from human hair follicle possesses the properties of primitive cells and supports the hypothesis that HFSC resides in the bulge area.

Cell Differentiation↗

PubMed2006

Mechanism of gating and ion conductivity of a possible tetrameric pore in aquaporin-1.

While substrate permeation through monomeric pores of aquaporins is well characterized, little is known about the possible tetrameric pore. AQP1 has been suggested to function as an ion channel upon cGMP activation, although this idea has been controversial. Taking a theoretical and experimental approach, we demonstrate that the current might arise through the tetrameric pore and propose a plausible mechanism for conduction and gating. In response to simulated ion permeation, immediate hydration of the putative central pore was facilitated by moderate conformational changes of pore-lining residues. cGMP is found to interact with an unusually arginine-rich, cytoplasmic loop (loop D) facilitating its outward motion, which is hypothesized to trigger the opening of a cytoplasmic gate. Physiological analyses of wild-type AQP1 and a designed mutant in which two arginines of the gating loop are replaced by alanine provide experimental support for identifying a key component of the proposed mechanism.

Amino Acid Sequence↗

PubMed2006

Primary renal zygomycosis due to Rhizopus oryzae.

Primary renal zygomycosis is a rare fungal infection, and only 45 cases have been reported in the literature. The major etiologic agents of the disease were Mucor spp., Rhizomucor spp., Rhizopus spp. and Absidia spp. Here we report a case of primary renal zygomycosis due to Rhizopus oryzae infection. The patient had systemic lupus erythematosus and was treated with corticosteroids. He had frequent micturition, urodynia and passed amorphous and membranous-looking masses through the urethra several times prior to admission. Histopathological examination of the mass showed numerous broad and nonseptate hyphae. Rhizopus oryzae was isolated from the mass. We also reviewed the clinical features of primary renal zygomycosis in the literature.

Adult↗

PubMed2006

A case of subcutaneous phaeohyphomycosis caused by Chaetomium globosum and the sequences analysis of C. globosum.

A 14-year-old boy developed painful erythema and necrosis on his face with petechia on his upper extremities. Microscopically, necrotic tissue treated with potassium hydroxide showed branched, dematiaceous, septate hyphae. Chaetomium globosum was isolated repeatedly from the necrotic tissues. Morphology and thermotolerance test of the pathogen were also studied. The internal transcribed spacer region in rRNA gene was amplified and sequenced. The sequence of this patient matched well with that of C. globosum in GenBank and from other patients and environment.

Adolescent↗

PubMed2006

[Primary culture and morphologic observation of eutopic and ectopic endometrial cells from patients with endometriosis].

OBJECTIVE: To explore the method of primary culture for endometriotic cells and to find out the differences in morphological manifestations among endometriotic cells and eutopic endometrial cells sampled from patients with endometriosis and endometriosis-free women. METHODS: Endometriotic and eutopic endometrial cells were cultured by modified method of primary culture. The endometriotic cell types were observed and differentiated under optical and electron microscopes. RESULTS: The success rates for culture of eutopic endometrial cells from endometriosis-free women and patients with endometriosis were 91.67% and 93.75% respectively. The success rate for culture of endometriotic cells was 75.00%. The size of endometriotic glandular cells was similar to those of eutopic endometrial glandular cells from endometriosis-free women and patients with endometriosis. The chromatin was manifold and the nucleus was augmented in the endometriotic glandular cells. The endometriotic stromal cells were smaller than the eutopic endometrial stromal cells from endometriosis-free women and patients with endometriosis. Many tiny villi and protuberances on plasma membrane could be seen in the endometriotic stromal cells. CONCLUSION: The success rate for culture of endometriotic cells can be elevated through improving the method of primary culture. The ultrastructures of endometriotic glandular and stromal cells are obviously different from those of eutopic endometrial glandular and stromal cells from endometriosis-free women and patients with endometriosis.

Adult↗

PubMed2006

[Effect of Yishenqinghuo compound on biological characteristics of rat bone marrow stromal cells].

OBJECTIVE: To evaluate the effect of Yishenqinghuo recipe on biological characteristic of rat bone marrow stromal cells (BMSCs) and search for the function and mechanism of this recipe in treatment of periodontitis. METHODS: 12- to 15-month-old SD rats were allocated into 5 groups. Group A: control group (with no periodontitis model, fed with the same dosage of saline as Group D); Group B: model group (with periodontitis model, fed with the same dosage of saline as Group D); Group C: high dosage group (with periodontitis model, fed with a high dosage of medicine); Group D: middle dosage group (with periodontitis model, fed with a middle dosage of medicine); and Group E: low dosage group (with periodontitis model, fed with a low dosage of medicine). Ten days later, serums were collected from all the five groups for in vitro cultivation of BMSCs. RESULTS: There was displayed a similarity in effect between the serum collected from Group C1 (serum collected 0.5 h after the last gavage of Group C) and that from Group A after the last gavage, the effect being the best in terms of proliferation of BMSCs. A comparison with the other groups had revealed a striking difference (P < 0.01), with Group B having turned out to be the worst. The serum from Group C2 (serum collected 1 h after the last gavage of Group C) after the last gavage could best enhance the generation and activity of ALP, having demonstrated a significant difference (P < 0.01) in comparison with the other groups. CONCLUSION: Yishenqinghuo recipe can improve the proliferation of BMSCs and facilitate the differentiation to osteoblast.

Animals↗

PubMed2005

Electroacupuncture suppresses surgical trauma stress-induced lymphocyte apoptosis in rats.

Cumulative evidences suggested that electroacupuncture (EA) could modulate immune function, but the mechanism needs further study. In the present study, the effect of EA on surgical trauma stress-induced lymphocyte apoptosis was investigated by using DNA gel electrophoresis, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay, and Western blot for Fas protein expression. The results showed that rats with surgical trauma stress exhibited a significant reduction in splenic cellularity. Increase in apoptotic cell death and Fas (CD95/Apo-1) expression in splenic lymphocytes was also observed. EA could suppress the increase of apoptosis and Fas protein expression in splenic lymphocytes induced by the surgical trauma stress. These results implied that EA could decrease splenic lymphocytes apoptosis via inhibiting Fas protein expression; consequently prevent deleterious immunological changes in the post-operative state.

Animals↗

PubMed2005

Polarization-dependent supercontinuum generation from light filaments in air.

We investigate polarization-dependent properties of the supercontinuum emission generated from filaments produced by intense femtosecond laser pulses propagating through air over a long distance. The conversion efficiency from the 800-nm fundamental to white light is observed to be higher for circular polarization than for linear polarization when the laser intensity exceeds the threshold of the breakdown of air.

Journal Article↗