Biomedical subjects

L Lu

Publications and source records attributed to L Lu.

At least 127 records · Page 7Linked to original sources

PubMed2001

[Labyrinthine fistula caused by chronic suppurative otitis media].

OBJECTIVE: To study the clinical feature and surgical management of labyrinthine fistula caused by chronic suppurative otitis media (CSOM). METHOD: A retrospective study of 450 patients with CSOM who underwent radical mastoidectomy between the years 1992 to 1999 in Department of Otolaryngology, Xijing Hospital was conducted. RESULT: 20 patients (4.4%) with labyrinthine fistula caused by CSOM were found. The average history of ear drainage was 22 years, 18 patients (90%) had subjective hearing loss, and 13 patients (65%) had dizziness. The fistula test was positive in 9 patients (45%). 2 patients had anacusis in the affected ear. The preoperative pure tone average for bone conduction thresholds was less than 30 dB in 11 patients, between 31 and 50dB in 3 patients, and more than 51 dB in 4 patients. The ears with a positive fistula test had worse preoperative hearing than those with negative test (P < 0.01). The fistula was detected by CT in 2 of 9 patients. Cholesteatoma was present in 18 patients (90%) and granulation tissue was present in 2 patients (10%). The lateral semicircular canal was the site of labyrinthine fistula. The lesion at the site of fistula was completely removed in 17 patients and exteriorized in the remaining 3. CONCLUSION: There are no reliable methods at present for preoperative diagnosis of labyrinthine fistula, ultimately, the most reliable way to identify a fistula is during surgery. The method of manipulation of labyrinthine fistula is based on the concrete conditions of fistula and patient.

Adult↗

PubMed2001

[The effect of culture conditions on the fatty acid composition in the mycelium of the Cephalosporium sp].

The optimal condition of Cephalosporium sp. to culture mycelia and accumulate polyunsaturated fatty acid (PUFA) was researched. The optimal culture condition to get mycelium productivity was: maltose 60 g/L, KNO3 3 g/L, initial pH 6.0, 100 mL medium in 500 mL flask, seeding 25% (v/v), 25 degrees C culture it for 10 days. The optimal condition to accumulation PUFA proportion to total fatty acid was: glucose 10-20 g/L, NH4Cl or (NH4)2SO4 3 g/L, initial pH 4.0, 100 mL medium in 500 mL falsk, seeding 10-20% (v/v) and lighted it when it was cultured. It was suggested that two step could be used in the producing progress. A proposal was put forward that the oileic acid transformed to linoleic acid was the key step to produce PUFA. This proposal gave a base to research the optimal culture condition and enzyme regulation.

Acremonium↗

PubMed2001

Experiment study of effect of perfluorohexyloctane on corneal endothelial cells.

PURPOSE: To investigate the effect of Perfluorohexyloctane (F6H8) on corneal endothelial cells(CEC) of rabbit eyes. METHODS: Fifteen New Zealand white rabbits were divided into two groups: experimental group(F6H8) and control group(BSS). All rabbits underwent anterior chamber injection of 0.15 ml F6H8 or BSS. Slit-lamp biomicroscopy and corneal endothelium photography were performed pre-operatively and postoperatively. Histopathological examination and Transmission electron microscopy(TEM) were done after the rabbits were sacrificed. RESULTS: All the corneas were clear. Since 4 weeks after operation, the endothelial cells were markedly irregular in size and shape and the number of endothelial cells was markedly decreased. Multilayered retrocorneal membranes(RCM) grew gradually 2 weeks after surgery. Vacuolar degeneration was seen in some endothelial cells. Nuclear degeneration and edema of plasma were seen in TEM. CONCLUSION: Corneal endothelial cell degenerated after contacting with F6H8 for 2-4 weeks. As a silicone solvent, it should be removed completely after injection. We don't recommend it to be used as a new intraocular temponade.

Animals↗

PubMed2001

[A preliminary study of a hearing screening model for newborn].

OBJECTIVE: To search for a hearing screening model for newborn and to investigate the prevalence of newborn hearing loss in our country. METHODS: The distortion product otoacoustic emissions (DPOAE) was used to test the hearing in 2,998 of 3,075 newborns before discharge. Otoacoustic emissions (OAE) was again used for cases failed in the hospital screening 4 weeks later. Those cases failed in both screening steps were finally tested by auditory brainstem response (ABR). All infants failed in ABR test received diagnostic evaluation audiologically to identify the category and degree of hearing loss. The pass criterion of DPOAE was defined as signal-noise-ratio (SNR) exceeding 6 dB in 4 of 5 frequencies between 1.5-6 kHz. The pass criterion of ABR was the presence of wave V in response to 35 dB nHL click stimuli. RESULTS: The OAE screening in the hospital showed that 2,710 (90.4%) newborns passed the first test. Two hundred and sixty three of 288 newborns passed the second OAE screening after one month. Six of 25 infants failed in ABR test were eventually identified to be hearing impaired. CONCLUSION: Two-stages screening, combining OAE and ABR tests, may be an ideal model for newborn hearing screening. The prevalence of congenital hearing loss is similar to that reported in the literature.

Evoked Potentials, Auditory, Brain Stem↗

PubMed2001

[A comparative study on sterols of ethanol extract and water extract from Hericium erinaceus].

OBJECTIVE: To study the pharmaceutic chemical basis of the different medicinal effects, and to compare and analyze the sterols in Hericium erinaceus mycelia and its ethanol extract, water extract derived from solid fermented mycelia. METHOD: The components of Hericium erinaceus mycelia and two kinds of extract were compared with some biochemical methods such as GC, RP-HPLC, etc. Sterol composition in Hericium erinaceus mycelia was determined by using GC-mass spectrometry. RESULTS: The content of crude polysaccharide, water-soluble protein and fatty acid of ethanol extract showed no obvious advantage over its water extract. However, there was significant difference between two kinds of extract in the content of sterols. And ergostane derivatives, beta-sitosterol and C28 sterol with four bonds were detected as the major sterols in Hericium erinaceus mycelia, among which ergosterol was the principal sterol. CONCLUSION: Sterols in Hericium erinaceus exist mainly in ethanol extract. And three sterols are found for the first time from Hericium erinaceus, which are ergostane derivatives, beta-sitosterol and C28 sterol with four bonds.

Basidiomycota↗

PubMed2001

Gut barrier function damage following multiple firearm injuries in a porcine model.

OBJECTIVE: To study the characteristics and pathogenesis of gut barrier damage following multiple firearm injuries in a porcine model. METHODS: Twenty-four small pigs were divided into 4 groups: control group (n = 6, group C), group H (n = 6, gunshot-induced tangential fracture of parietal bone), group L (n = 6, gunshot-induced comminuted fracture of bilateral femora) and group M (n = 6, combined group H + L). Gastric intramucosal pH (pHi), plasma endotoxin levels in portal vein, and plasma D-lactate levels were measured and blood samples were cultured at different intervals after trauma. The animals were sacrificed at 72 h following trauma and intestinal tissues were harvested for pathological examination and diamine oxidase (DAO) activity measurement. RESULTS: In group M at 72 h, pHi was significantly lower than that of group H and L ( P < 0.01), and plasma endotoxin level was significantly higher than that of group H (P < 0.01) and group L (P < 0.05). Simultaneously, in group M, D-lactate level was markedly higher than that of group H ( P < 0.01), and incidence of positive blood culture was much higher than that of group H and L ( P < 0.05). Necrosis and exfoliation were revealed at ileum villus top in all trauma groups, especially in group M, in which ileum DAO activity declined most significantly as well. CONCLUSION: Multiple trauma is prone to cause gastrointestinal ischemia even without hemorrhagic shock. The damage of gut barrier in multiple trauma appears to be more severe than that in one-site trauma, thereby promoting gut-derived endotoxemia and bacterial translocation and contributing to the development of endogenous infection.

Amine Oxidase (Copper-Containing)↗

PubMed2001

[Molecular orientation of copper phthalocyanine derivative in copper phthalocyanine-Fe2O3 nanoparticles alternating LB films].

Copper phthalocyanine-Fe2O3 nanoparticles alternating thin films were fabricated by Langmuir-Blodgett technique. Molecular orientation of [4-(4'-benzyloxy phenyl sulfonyl)phenoxy]-tris-4-(2,4-di-t-phenoxy) phthalocyanine copper (II) in its alternating LB films, deposited at different conditions, was studied by polarized UV-Vis spectra. The tilt extent of the copper phthalocyanine molecule on its LB films increases with the surface pressure of the subphase increasing on the same subphase, or with Fe2O3 concentration decreasing at the same pressure. The orientation of the copper phthalocyanine derivative is important for the gas-sensing properties. The bigger the tilt extent of the phthalocyanine molecule is, the greater the sensitivity of the film is.

Ferrous Compounds↗

PubMed2000

An expansion phase precedes terminal erythroid differentiation of hematopoietic progenitor cells from cord blood in vitro and is associated with up-regulation of cyclin E and cyclin-dependent kinase 2.

The dynamics of cell cycle regulation were investigated during in vitro erythroid proliferation and differentiation of CD34(+) cord blood cells. An unusual cell cycle profile with a majority of cells in S phase (70.2%) and minority of cells in G1 phase (27.4%) was observed in burst-forming unit-erythrocytes (BFU-E)-derived erythroblasts from a 7-day culture of CD34(+) cells stimulated with interleukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), Steel factor, and Epo. Terminal erythroid differentiation was accompanied by a rapid increase of G0/G1 phase cells. Expression of cyclin E and cyclin-dependent kinase 2 (cdk2) correlated with the proportion of S phase cells. Cyclin D3 was moderately up-regulated during the proliferation phase, and both cyclin E and D3 were rapidly down-regulated during terminal differentiation. This suggests that the high proliferation potential of erythroblasts is associated with temporal up-regulation of cyclin E and cdk2. (Blood. 2000;96:3985-3987)

CDC2-CDC28 Kinases↗

PubMed2000

Modules in the photoreceptor RGS9-1.Gbeta 5L GTPase-accelerating protein complex control effector coupling, GTPase acceleration, protein folding, and stability.

RGS (regulators of G protein signaling) proteins regulate G protein signaling by accelerating GTP hydrolysis, but little is known about regulation of GTPase-accelerating protein (GAP) activities or roles of domains and subunits outside the catalytic cores. RGS9-1 is the GAP required for rapid recovery of light responses in vertebrate photoreceptors and the only mammalian RGS protein with a defined physiological function. It belongs to an RGS subfamily whose members have multiple domains, including G(gamma)-like domains that bind G(beta)(5) proteins. Members of this subfamily play important roles in neuronal signaling. Within the GAP complex organized around the RGS domain of RGS9-1, we have identified a functional role for the G(gamma)-like-G(beta)(5L) complex in regulation of GAP activity by an effector subunit, cGMP phosphodiesterase gamma and in protein folding and stability of RGS9-1. The C-terminal domain of RGS9-1 also plays a major role in conferring effector stimulation. The sequence of the RGS domain determines whether the sign of the effector effect will be positive or negative. These roles were observed in vitro using full-length proteins or fragments for RGS9-1, RGS7, G(beta)(5S), and G(beta)(5L). The dependence of RGS9-1 on G(beta)(5) co-expression for folding, stability, and function has been confirmed in vivo using transgenic Xenopus laevis. These results reveal how multiple domains and regulatory polypeptides work together to fine tune G(talpha) inactivation.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2000

Induction of ref-1 ensures AP-1 activation in intracellular oxidative environment of IL-2-stimulated BA/F3beta cells.

Our previous study of interleukin-2 (IL-2) signaling found that redox factor-1 (Ref-1) mRNA was upregulated by IL-2. In this study, we further studied the function of Ref-1 in the potential redox regulation of IL-2 signaling in BA/F3beta cells. Western blot analysis confirmed that IL-2 stimulation increases Ref-1 protein. Flow cytometric assay by using 2',7'-dichlorofluorescin diacetate indicated that IL-2 stimulation results in an oxidative shift of intracellular environment. However, IL-2-induced activator protein-1 (AP-1) is oxidation-sensitive. Gel shift assays of nuclear extracts immunodepleted of Ref-1 protein demonstrated that IL-2-induced AP-1 DNA binding is dependent on the presence of Ref-1. This was further confirmed by the restoration of AP-1 DNA binding upon the re-addition of immunoprecipitated Ref-1. Additionally, reporter gene assays showed that AP-1 transcriptional activity was enhanced by the overexpression of Ref-1 and attenuated by the introduction of antisense Ref-1. These results suggest that the induction of Ref-1 ensures AP-1 activation in the intracellular oxidative environment of IL-2-stimulated BA/F3beta cells.

Base Sequence↗

PubMed2000

Inhibition of the amygdala and hippocampal calcium/calmodulin-dependent protein kinase II attenuates the dependence and relapse to morphine differently in rats.

Learning and memory have been suggested to play an important role in the development of opiate addiction. Based on the recent finding that calcium/calmodulin protein kinase II (CaMKII) is essential in learning and memory processes, the present study was performed to examine whether inhibition of hippocampal and amygdala CaMKII prevents the dependence and relapse to morphine. The results showed that inhibition of CaMKII by microinjection of specific inhibitors KN-62 into hippocampus decreased the morphine withdrawal syndromes induced by opiate antagonist naloxone. In contrast, inhibition of CaMKII in amygdala failed to do so. Microinjection of KN-62 into both hippocampus and amygdala suppressed the development of formation and reactivation of morphine conditioned place preference (CPP). However, inhibition of CaMKII in amygdala, but not in hippocampus, could attenuate the maintenance of morphine CPP. These results suggest that hippocampal CaMKII is critically involved in the development of morphine physical and psychological dependence, and amygdala CaMKII is some different from hippocampal CaMKII in regulating the dependence and relapse to opiates. Inhibition of this kinase may have some therapeutic benefit in the treatment of opiate dependence and relapse.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2000

NGF-Dependent neurite outgrowth in PC12 cells overexpressing the Src homology 2-domain protein shb requires activation of the Rap1 pathway.

The Src homology 2 (SH2) domain adaptor protein Shb has been shown to transmit NGF- and FGF-2-dependent differentiation signals in PC12 cells. To study if this involves signaling through the small GTPase Rap1, Rap1 activity was assessed in Shb-overexpressing PC12 cells. We demonstrate that NGF and EGF induce Rap1 activation in PC12-Shb cells, while FGF-2 fails to do so. However, PC12 cells expressing Shb with an inactivated SH2 domain do not respond to NGF stimulation with Rap1 activation. The CrkII SH2 domain interacts with Shb and a 130- to 135-kDa phosphotyrosine protein present mainly in PC12-Shb cells and these interactions may thus relate to the effect of Shb on Rap1 activation. Transient expression of RalGDS-RBD or Rap1GAP to block the Rap1 pathway reduces the NGF-dependent neurite outgrowth in PC12-Shb cells. These results suggest a role of Shb in NGF-dependent Rap1 signaling and this pathway may be of significance for neurite outgrowth under certain conditions.

Animals↗

PubMed2000

Corticotropin-releasing factor receptor type I mediates stress-induced relapse to opiate dependence in rats.

The possible effect of different corticotropin-releasing factor receptor (CRFR) antagonists (alpha-helical CRF, CP-154,526 and AS-30) on the maintenance and reactivation of morphine-conditioned place preference (CPP) induced by morphine or footshock stress, respectively, were investigated in rats. The results show that morphine-induced maintenance of CPP was not affected by pretreatment with any CRFR antagonists. However, morphine-induced the reactivation of CPP was significantly attenuated by pre-administration of 10 microg alpha-helical CRF (i.c.v.). The maintenance of morphine CPP could be induced by repeated footshock and this effect was significantly attenuated by pretreatment of 10 microg alpha-helical CRF (i.c.v.) and 10 mg CP-154,526 (i.p.). Furthermore, following a 28-day extinction of morphine CPP, a single footshock could again elicit the reactivation of place preference that was blocked by pretreatment with 10 microg alpha-helical CRF (i.c.v.) and 1 or 10 mg CP-154,526 (i.p.). The present study demonstrates that CRFR type 1, but not CRFR type 2, mediates the stress-induced maintenance and reactivation of morphine CPP. These findings suggest that CRFR type 1 antagonists might be of some value in the treatment and prevention of stress-induced relapse to drug dependence long after detoxification.

Animals↗

PubMed2000

Preferential induction of Th1 responses by functionally mature hepatic (CD8alpha- and CD8alpha+) dendritic cells: association with conversion from liver transplant tolerance to acute rejection.

BACKGROUND: Liver grafts are accepted across major histocompatibility barriers in mice without immunosuppressive therapy. Potentially tolerogenic immature donor dendritic cells (DC) may play a key role in this phenomenon, but recovery of purified DC from normal livers for functional analysis is inherently difficult. Administration of in vitro propagated immature donor DC to recipients of different types of allograft can prolong transplant survival. By contrast, marked increases in donor liver DC as the result of Flt3 ligand (FL) administration and the resulting augmentation of allostimulatory activity within host lymphoid tissue, is associated with acute graft rejection. Here, we compared the capacity of in vitro generated normal liver immature DC and FL-treated donor liver DC to induce alloimmune CD4+ T helper (Th) 1/Th2 and CD8+ T cytotoxic (Tc) 1/Tc2 responses, in vitro and in vivo. METHODS: B10 (H2b, IAb) immature liver DC were propagated from normal hepatic nonparenchymal cells in granulocyte macrophage-colony stimulating factor (GM-CSF) for 6-8 days. Freshly isolated DC from livers of FL-treated mice (FL-liver DC) were cultured overnight (o/n) in GM-CSF, and both myeloid (CD11c+ CD8alpha-) and lymphoid DC (CD11c+ CD8alpha+) flow-sorted for functional analysis. Proliferative activity and production of interferon (IFN)-gamma, interleukin (IL)-4, and IL-10 by naive C3H (H2k, IEk) T cells in response to DC stimulation was assessed by [3H]thymidine incorporation, and by multicolor flow cytometric analysis, respectively, after 3-day mixed leukocyte reactions. To investigate their in vivo trafficking, B10 DC were injected subcutaneously into normal C3H mice. Sections of lymphoid tissue were immunostained for donor MHC class II+ (IAb+) cells, and for IFN-gamma, IL-4, and IL-10 production. Donor cells and clusters of specific cytokine-secreting cells were enumerated. RESULTS: Both in vitro propagated normal liver-derived DC, and freshly isolated bulk FL-liver DC showed an immature phenotype (MHC class II(lo), CD40-, CD80-, and CD86-) and were weak stimulators of naive allogeneic T cells. After o/n incubation in GM-CSF, both CD8alpha- and CD8alpha+ FL-liver DC exhibited marked up-regulation of surface MHC class II and costimulatory molecules, and acquired potent stimulatory activity for Th1 (mainly) and Th2 cells. Both in vitro propagated immature DC and o/n-cultured mature FL-liver DC homed in vivo to host lymphoid tissues, but with different kinetics. Whereas the mature allogeneic FL-liver DC induced IFN-gamma+ clusters in splenic T-cell areas within 2 days, the IFN-gamma response to immature DC was much slower and weaker. CONCLUSIONS: FL-treated donor livers that are rejected acutely contain markedly enhanced numbers of myeloid (CD8alpha-) and lymphoid (CD8alpha+) DC, many of which are capable of maturing rapidly into strong inducers of Th1 and Tcl responses. Substantial differences in quantity, and both the phenotypic and functional characteristics of the DC constituency of donor livers, may contribute significantly toward the distinct outcomes of liver transplant tolerance and rejection.

Acute Disease↗

PubMed2000

Platelet-derived growth factor-mediated signaling through the Shb adaptor protein: effects on cytoskeletal organization.

The Src homology (SH) 2 domain adaptor protein Shb has previously been shown to interact with the platelet-derived growth factor (PDGF)-beta receptor. In this study we show an association between Shb and the PDGF-alpha receptor which is mediated by the SH2 domain of Shb and involves tyrosine residue 720 in the kinase insert domain of the receptor. To assess the role of Shb in PDGF-mediated signaling, we have overexpressed wild-type Shb or Shb carrying a mutation (R522K) which renders the SH2 domain inactive, in Patch mouse (PhB) fibroblasts expressing both PDGF receptors (PhB/Ralpha). Overexpression of wild-type Shb, but not the R522K Shb mutant, affected PDGF-mediated reorganization of the cytoskeleton by decreasing membrane ruffle formation and stimulating the generation of filopodia relative the parental control cells. In addition, the PDGF-induced receptor-associated phosphatidylinositol 3'-kinase activity and phosphorylation of Akt was similar in both PhB/Ralpha/Shb and PhB/Ralpha/ShbR522K cells compared with the parental control, whereas the activation of Rac in response to PDGF-BB was diminished only in the PhB/Ralpha/Shb cells. We conclude that Shb plays a role in PDGF-dependent regulation of certain cytoskeletal changes by modulating the ability of PDGF to activate Rac.

3T3 Cells↗

PubMed2000

Controlled release of transforming growth factor beta1 from biodegradable polymer microparticles.

Recombinant human transforming growth factor beta1 (TGF-beta1) was incorporated into biodegradable microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) at 6 ng/1 mg microparticles. Fluorescein isothiocynate labeled bovine serum albumin (FITC-BSA) was coencapsulated as a porogen at 4 microg/1 mg of microparticles. The effects of PEG content (0, 1, or 5 wt %) and buffer pH (3, 5, or 7.4) on the protein release kinetics and the degradation of PLGA were determined in vitro for up to 28 days. The entrapment yield of TGF-beta1 was 83.4 +/- 13.1 and 54.2 +/- 12.1% for PEG contents of 0 and 5%, respectively. The FITC-BSA and TGF-beta1 were both released in a multiphasic fashion including an initial burst effect. Increasing the PEG content resulted in the decreased cumulative mass of released proteins. By day 28, 3.8 +/- 0. 1 and 2.8 +/- 0.3 microg (based on 1 mg microparticles) of loaded FITC-BSA and 3.4 +/- 0.2 and 2.2 +/- 0.3 ng of loaded TGF-beta1 were released into pH 7.4 phosphate buffered saline (PBS) from microparticles with 0 and 5% PEG, respectively. Aggregation of FITC-BSA occurred at lower buffer pH, which led to decreased release rates of both proteins. For microparticles with 5% PEG, 2.3 +/- 0.1 microg of FITC-BSA and 2.0 +/- 0.2 ng of TGF-beta1 were released in pH 7.4 buffer after 28 days, while only 1.7 +/- 0.3 microg and 1.3 +/- 0.4 ng of the corresponding proteins were released in pH 3 buffer. The degradation of PLGA was also enhanced at 5% PEG content, which was significantly accelerated at acidic pH conditions. The calculated half-lives of PLGA were 20.3 +/- 0.9 and 15.9 +/- 1.2 days for PEG contents of 0 and 5%, respectively, in pH 7.4 PBS and 14.8 +/- 0.4 and 5.5 +/- 0.1 days for 5% PEG in pH 7.4 and 3 buffers, respectively. These results suggest that PLGA/PEG blend microparticles are useful as delivery vehicles for controlled release of growth factors.

Animals↗

PubMed2000

Effects of transforming growth factor beta1 released from biodegradable polymer microparticles on marrow stromal osteoblasts cultured on poly(propylene fumarate) substrates.

Recombinant human transforming growth factor beta1 (TGF-beta1) was incorporated into microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) to create a delivery vehicle for the growth factor. The entrapment efficiency of TGF-beta1 in the microparticles containing 5% PEG was 40.3 +/- 1.2% for a TGF-beta1 loading density of 6.0 ng/1 mg of microparticles. For the same loading, 17.9 +/- 0.6 and 32.1 +/- 2.5% of the loaded TGF-beta1 was released after 1 and 8 days, respectively, followed by a plateau for the remaining 3 weeks. Rat marrow stromal cells showed a dose response to TGF-beta1 released from the microparticles similar to that of added TGF-beta1, indicating the activity of TGF-beta1 was retained during microparticle fabrication and after TGF-beta1 release. An optimal TGF-beta1 dosage of 1.0 ng/mL was determined through a 3-day dose response study for maximal alkaline phosphatase (ALP) activity. The TGF-beta1 released from the microparticles loaded with 6.0 ng TGF-beta1/1 mg of microparticles for the optimal dosage of TGF-beta1 enhanced the proliferation and osteoblastic differentiation of marrow stromal cells cultured on poly(propylene fumarate) substrates. The cells showed significantly increased total cell number, ALP activity, and osteocalcin production with values reaching 138,700 +/- 3300 cells/cm(2), 22.8 +/- 1.5 x 10(-7) micromol/min/cell, and 15.9 +/- 1.5 x 10(-6) ng/cell, respectively, after 21 days as compared to cells cultured under control conditions without TGF-beta1. These results suggest that controlled release of TGF-beta1 from the PLGA/PEG blend microparticles may find applications in modulating cellular response during bone healing at a skeletal defect site.

Animals↗

PubMed2000

Endostatin-induced tyrosine kinase signaling through the Shb adaptor protein regulates endothelial cell apoptosis.

Endostatin, which corresponds to the C-terminal fragment of collagen XVIII, is a potent inhibitor of angiogenesis. Fibroblast growth factor-2 (FGF-2)-induced angiogenesis in the chicken chorioallantoic membrane was inhibited by endostatin, but not by an endostatin mutant R158/270A, lacking heparin-binding ability. Endostatin was internalized by endothelial cells, but not by mouse fibroblasts. Treatment of murine brain endothelial (IBE) cells with endostatin reduced the proportion of cells in S phase, whereas growth-arrested IBE cells in collagen gels treated with endostatin displayed enhanced tubular morphogenesis. IBE cells overexpressing Shb, an adaptor protein implicated in angiostatin-induced apoptosis, displayed elevated apoptosis and decreased tubular morphogenesis in collagen gels in response to endostatin when added together with FGF-2. Induction of apoptosis was dependent on the heparin-binding ability of endostatin and the expression of Shb with a functional Src homology 2 (SH2)-domain. Endostatin treatment for 10 minutes or 24 hours induced tyrosine phosphorylation of Shb and formation of multiprotein complexes. An Shb SH2 domain fusion protein precipitated a 125-kd phosphotyrosyl protein in endostatin-treated cells. The 125-kd component either contained intrinsic tyrosine kinase activity or occurred in complex with a tyrosine kinase. In conclusion, our data show that endostatin induces tyrosine kinase activity and enhanced apoptosis in FGF-treated endothelial cells.

Adaptor Proteins, Signal Transducing↗