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Biomedical subjects

Q Hou

Publications and source records attributed to Q Hou.

At least 19 recordsLinked to original sources
PubMed2006

Granzyme K cleaves the nucleosome assembly protein SET to induce single-stranded DNA nicks of target cells.

Although granzymes (Gzms) A- and B-induced cell death pathways have been defined, little is known about how other orphan Gzms function in CTL-mediated cytotoxicity. GzmK and A are tryptases among all the Gzms of humans and they are closely linked on the same chromosome. In this study, we showed that GzmK can be efficiently delivered into target cells with a cationic lipid protein transfection reagent Pro-Ject. We found human GzmK triggers rapid cell death independently of caspase activation. The features of death are characterized by rapid externalization of phosphatidylserine, nuclear morphological changes and single-stranded DNA nicks. GzmK hydrolyzes the nucleosome assembly protein SET in its recombinant and native forms or in intact cells. Cleavage of SET by GzmK abrogates its nucleosome assembly activity. After GzmK loading, SET and DNase NM23H1 rapidly translocate into the nucleus and SET is cleaved, where the nuclease activity of NM23H1 is activated to nick chromosomal DNA.

Caspases↗
PubMed2003

Apoptosis modulatory activities of transiently expressed Bcl-2: roles in cytochrome C release and Bax regulation.

Bcl-2 and Bcl-X(L) are pro-survival members of the Bcl-2 family. These proteins have been shown to antagonize the pro-apoptotic activity of Bax and promote cell survival through blocking Bax translocation from the cytosol to mitochondria and by preventing the release of cytochrome c. However, it has been recently reported that transiently expressed Bcl-2 unexpectedly leads to significant cell toxicity. To study this intriguing phenomenon, we have carried out further analyses into the properties of transiently expressed Bcl-2. We found that various isoforms of human and different species of Bcl-2 were equally capable of inducing apoptosis. In addition, we discovered that transient expression of Bcl-2, unlike its pro-survival homolog Bcl-X(L), can lead to the release of cytochrome c from mitochondria and that the resulting cell death can be inhibited by caspase and calpain inhibitors. Moreover, we have shown that unlike the pro-apoptotic protein Bid, the toxicity associated with the transient expression of Bcl-2 occurs independent of the activity of the endogenous Bax. Finally, we found that in spite of its intrinsic toxicity, transiently expressed Bcl-2 is fully capable of blocking the ectopically expressed Bax from localizing to mitochondria. Taken together, these studies demonstrate that transiently expressed Bcl-2 displays opposing functional properties.

Animals↗
PubMed2001

Molecular dynamics used in radiation therapy.

In this Letter, classical molecular dynamics is used to deal with optimization problems occurring in intensity modulated radiation therapy. By introducing the concepts of virtual atom and virtual cluster, the optimization process in this kind of therapy can be considered as an analogy to finding the equilibrium configuration of a cluster. This viewpoint gives great insight into the optimization problems. To show how the idea works, a dose-based objective function is adopted to obtain the optimized intensity profiles. The results and high computational efficiency show that molecular dynamics is applicable clinically for this therapy. The idea presented here also could be inspiring to other fields where optimization problems exist.

Algorithms↗
PubMed2001

Some features of intestinal absorption of intact fibrinolytic enzyme III-1 from Lumbricus rubellus.

In order to investigate whether earthworm fibrinolytic enzyme III-1 (EFE-III-1) isolated from Lumbricus rubellus is capable of transporting into blood through intestinal epithelium and keeping its biological function in circulation, we have raised an antibody against EFE-III-1. The immunological results showed that 10-15% of intact EFE-III-1 was absorbed by the intestinal epithelium with the incubation chamber method [Vilhardt and Lundin, Acta Physiol. Scand. 126 (1986) 601-607]. The enzyme could be detected in the intestinal epithelial cells by immunohistochemistry. Furthermore, immunoreactive intact EFE-III-1 was found in serum or plasma after intraperitoneal injection of rats. Approx. 10% of the full-size enzyme could transport through the intestinal epithelium. The maximum remaining activity in blood could be assayed around 60 min after the intraperitoneal injection.

Amino Acid Sequence↗
PubMed2001

Renormalization group and perfect operators for stochastic differential equations.

We develop renormalization group (RG) methods for solving partial and stochastic differential equations on coarse meshes. RG transformations are used to calculate the precise effect of small-scale dynamics on the dynamics at the mesh size. The fixed point of these transformations yields a perfect operator: an exact representation of physical observables on the mesh scale with minimal lattice artifacts. We apply the formalism to simple nonlinear models of critical dynamics, and show how the method leads to an improvement in the computational performance of Monte Carlo methods.

Journal Article↗
PubMed2001

Anti-human platelet tetraspanin (CD9) monoclonal antibodies induce platelet integrin alpha IIb beta 3 activation in a Fc receptor-independent fashion.

OBJECTIVES: To characterize the activation of platelet integrin alpha IIb beta 3 induced by two anti-human platelet tetraspanin monoclonal antibodies (mAbs), HI117 and SJ9A4, and investigate their potential mechanism of action. METHODS: Using 125I-labeled human fibrinogen (Fg), specific Fg binding to human platelets induced by HI117 and SJ9A4 was measured. RESULTS: HI117 and SJ9A4 (10 micrograms/ml and 20 micrograms/ml) induced specific Fg binding to human platelets, suggesting that the two mAbs evoked activation of platelet integrin alpha IIb beta 3. Further study indicated that HI117 and SJ9A4 induced integrin alpha IIb beta 3 activation independent of platelet Fc-receptors, and that HI117 and SJ9A4-induced integrin alpha IIb beta 3 activation was inhibited by pretreatment of platelets with sphingosine, aspirin, apyrase, and/or PGI2. CONCLUSIONS: Anti-platelet tetraspanin (CD9) mAbs, HI117 and SJ9A4, can induce platelet integrin alpha IIb beta 3 activation independent of Fc-receptors. Three signaling pathways, namely thromboxane, secreted ADP, and cAMP pathways, may be involved in the process, with protein kinase C activation presumably being the common step of the three pathways.

Antibodies, Monoclonal↗
PubMed2001

[Inhibitory effects of hydrocortisone on human polymorphonuclear leukocyte adhesion to human synovial cell].

AIM: To investigate the inhibitory effects of hydrocortisone on human polymorphonuclear leukocyte (PMN) adhesion to human synovial cell (HSC), and to explore its mechanism. METHODS: MTT colorimetry was used to determine the adhesion effect of PMN to HSC. Cell-ELISA and RT-PCR methods were used to determine the expression of adhesion molecular ICAM-1 and VCAM-1. EMSA method was also used to observe the activity of nucleus transcription factor-kappa B (NF-kappa B). RESULTS: Hydrocortisone inhibited TNF-alpha (50 U.mL-1 for 12 hours) and IL-1 beta (50 U.mL-1 for 12 hours)-induced adhesion of PMN to HSC (IC50 2.05 x 10(-6) mol.L-1 and 2.13 x 10(-7) mol.L-1, respectively) in a concentration-dependent manner. Adhesion molecular VCAM-1 and ICAM-1 protein and mRNA (rather than ICAM-1) expression in HSC induced by TNF-alpha (50 U.mL-1) were inhibited significantly by hydrocortisone at 1 x 10(-6)-10(-5) mol.L-1. The activity of NF-kappa B was also extensively inhibited by hydrocortisone at 1 x 10(-6)-10(-5) mol.L-1. CONCLUSION: Hydrocortisone inhibited TNF-alpha-stimulated PMN-HSC adhesion, and expression of VCAM-1 by suppressing the activity of NF-kappa B.

Adult↗
PubMed2001

[Inhibitory effects of isorhapotigenin on IL-8 production and mRNA expression induced with TNF alpha in normal human synovial cells].

AIM: To study the effects of isorhapotigenin (Iso) on interleukin-8 (IL-8) production and mRNA expression in normal human synovial cells (HSC) induced with TNF alpha. METHODS: IL-8 were assayed with RIA method. The mRNA expression of IL-8 was detected by RT-PCR method. RESULTS: It was shown that TNF alpha at concentrations of 0.05 to 0.5 U.mL-1 for 24 h significantly increased IL-8 production. The expression of IL-8 mRNA was also promoted by TNF alpha (0.25 U.mL-1) for 6 h. Iso at the concentrations of 1 x 10(-6) mol.L-1 to 1 x 10(-5) mol.L-1 showed inhibitory effects on IL-8 production induced with TNF alpha (0.25 U.mL-1). The further study indicated that Iso at the concentrations of 1 x 10(-6) mol.L-1 to 1 x 10(-5) mol.L-1 inhibited IL-8 mRNA expression in HSC induced with TNF alpha (0.25 U.mL-1). CONCLUSION: TNF alpha promoted IL-8 production and mRNA expression in HSC. Iso inhibited IL-8 production and mRNA expression induced by TNF alpha (0.25 U.mL-1). This might be one of the anti-inflammatory mechanisms of Iso.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Anti-human platelet tetraspanin (CD9) monoclonal antibodies induce platelet integrin alphaIIbbeta3 activation in a Fc receptor-independent fashion.

OBJECTIVE: This study characterized the activation of platelet integrin alphaIIbbeta3 induced by two anti-human platelet tetraspanin monoclonal antibodies (mAbs), HI117 and SJ9A4. METHODS: Using 125I-labeled human fibrinogen(Fg), specific Fg binding to human platelets induced by HI117 and SJ9A4 was measured as indication of activation of platelet integrin alphaIIbbeta3 by the two mAbs. RESULTS: HI117 and SJ9A4 (10 microg/ml and 20 microg/ml) induced evident specific Fg binding to human platelets, suggesting that the two mAbs evoked activation of platelet integrin alphaIIbbeta3. Further study indicated that HI117 and SJ9A4 induced integrin alphaIIbbeta3 activation independent of platelet Fc-receptors, and that HI117 and SJ9A4-induced integrin alphaIIbbeta3 activation was inhibited by sphingosing, aspirin, apyrase, and/or PGI2. CONCLUSION: The anti-platelet tetraspanin (CD9) mAbs, HI117 and SJ9A4, can induce platelet integrin alphaIIbbeta3 activation independent of Fc-receptor. Three signaling pathways, i.e. thromboxane, secreted ADP, and cAMP pathways may be involved in the process, with protein kinase C activation presumably being the common step of the three pathways.

Antibodies, Monoclonal↗
PubMed1999

Reversible exposure of human platelet fibrinogen receptors by antiplatelet tetraspanin monoclonal antibodies via induction of a conformational change in membrane glycoprotein IIb/IIIa complex.

Antihuman platelet tetraspanin (CD9 antigen) monoclonal antibodies, HI117 and SJ9A4, can induce human platelet aggregation and secretion. As platelet aggregation is mediated by fibrinogen binding to its receptors exposed on platelet glycoprotein IIb/IIIa complex, we, therefore, investigated the induction of platelet fibrinogen receptors by HI117 and SJ9A4. It was found that HI117 and SJ9A4 induced specific fibrinogen binding to human platelets, suggesting that the two monoclonal antibodies evoked obvious exposure of fibrinogen receptors on human platelets. But in the absence of fibrinogen, the monoclonal antibody-exposed fibrinogen receptors gradually lost their capacity to bind fibrinogen and closed. Our results also showed that HI117 and SJ9A4, when activating platelets, caused a conformational change in glycoprotein IIb/IIIa complex, which must contribute to the exposure of functional fibrinogen receptors on this integrin. The effect of HI117 and SJ9A4 on glycoprotein IIb/IIIa complex seems, however, to be indirect, because the HI1117 and SJ9A4-induced fibrinogen binding was reduced by pretreatment of platelets with sphingosine, aspirin, apyrase, and/or PGI2. Taken together, we conclude that the antihuman platelet tetraspanin monoclonal antibodies, HI117 and SJ9A4, reversibly expose platelet fibrinogen receptors via inducing a conformational change in glycoprotein IIb/IlIa complex. Three signaling pathways, that is, thromboxane, secreted ADP, and cAMP pathways may be involved in this process, while protein kinase C activation seems to be the final common step of the three pathways.

Antibodies, Monoclonal↗
PubMed1999

[Intraoral one-stage curved osteotomy for prominent mandibular angle].

OBJECTIVE: This paper presents a new method of osteotomy for the prominent mandibular angle (PMA). METHODS: Two modifications have been made to the conventional procedures. The first is the one-stage curved osteotomy of the mandibular angle. The second is non-resection of the masseter muscle. The surgical procedure has been performed through an intraoral approach with a direct field of vision. RESULTS: From December 1996 to December 1997, a total of thirty-eight patients suffering from PMA have been operated on by this method with satisfactory results. The follow-up is 3 to 12 months. CONCLUSION: This method is a very simple and ideal procedure with much less complications for surgical treatment of PMA.

Adolescent↗
PubMed1996

Immunolocalization of estrogen receptor protein in the mouse blastocyst during normal and delayed implantation.

We previously showed that estrogen receptor (ER) mRNA is present in preimplantation mouse embryos. The apparent synthesis of ER mRNA by the blastocyst at the time of implantation when estrogen is required was of special interest. A demonstration of the presence of ER protein would support the idea that estrogen can act directly on the embryo. The mouse embryo at the blastocyst stage is differentiated into two cell types, the trophectoderm and the inner cell mass. To determine whether ER mRNA is translated into ER protein and its cell-specific distribution, immunocytochemical analyses were performed in mouse blastocysts. ER protein was detected in all cell types of the normal, dormant, or activated blastocyst. To trace the fate of ER in these cell types, immunocytochemistry was performed in implanting blastocysts and early egg cylinder stage embryos developed in culture. Again, ER was detected in all cells of the implanting blastocyst. At the early egg cylinder stage, continued expression of ER was observed in cells derived from the inner cell mass or the trophoblast. In trophoblast giant cells, ER was concentrated in small regions of the nucleus, possibly the nucleoli, which was similar to that observed in dormant and activated blastocysts. The embryonic expression of ER at such early stages in a broad array of cells suggests that ER may have a general role during early development.

Animals↗
PubMed1995

Embryonic estrogen receptors: do they have a physiological function?

In normal estrogen target tissues, estrogen action is mediated through a specific nuclear transcription factor, the estrogen receptor (ER). The site of estrogen action in the developing organism is therefore determined by cells that contain ER and other necessary tissue and gene-specific components for estrogen-mediated transcription. Immunocytochemical methods were used to determine the cellular localization and tissue distribution of ERs in reproductive tracts of mouse fetuses. Nuclear staining for ER was observed in reproductive tracts at fetal days 13 to 15. ERs were present in the precursors of both male and female reproductive tracts at these early developmental stages, which may be attributable to their similar embryonic origins. However, as the tissues undergo sexual differentiation at later fetal and early neonatal ages, ER increases in the female reproductive tracts as compared with the male. ER was detected by immunoblotting on fetal day 10 (before sexual differentiation) in extracts of whole mouse embryos. To determine whether ER and progesterone receptor genes are expressed earlier in development, we examined RNA from preimplantation mouse embryos using reverse transcriptase-polymerase chain reaction techniques. ER mRNA was found in oocytes and fertilized eggs. Message concentration declined at the 2-cell stage and reached its lowest level at the 5- to 8-cell stage. ER mRNA was not detectable at the morula stage but reappeared at the blastocyst stage. Progesterone receptor mRNA was not detectable until the blastocyst stage. The embryonic expression of ER and progesterone receptor genes in the blastocyst suggests a possible functional requirement for estrogen and progesterone receptors in preimplantation embryos.

Animals↗
PubMed1995

[Measurement of velocity of ophthalmic arterial blood flow in normal persons with color Doppler sonography].

The authors measured the velocity of the ophthalmic arterial blood flow with color Doppler sonography (Acuson-128, USA) in 246 eyes of 123 normal persons to evaluate exactly the changes of the blood supply in all ischemic fundus diseases and provide the reliable reference basis for the clinic. The average velocity of the ophthalmic arterial flow of the normal in the maximum contraction period (peak systolic velocity, PSV) is respectively 36.44 +/- 8.35cm/sec on the right and 36.94 +/- 11.30cm/sec on the left. There were no significant differences in PSV between the right and left eyes and between the male and female persons. We found that PSV of the ophthalmic artery in persons over 41 years old was significantly different from that in persons below that age, suggesting the age of 41 years old be the beginning of the senile process of systemic small blood vessels and providing a reference for anti-sensility. In the mean time, the velocity of ophthalmic arterial blood flow was also evaluated in 18 eyes with the acute attack of acute angle-closure glaucoma and 15 eyes at pre-clinical stage.

Adolescent↗
PubMed1994

[A case control study on risk factors of endometrial carcinoma in Tianjin].

A case-control study was conducted on risk factors of endometrial carcinoma in Tianjin. The data was analysed with chi 2 test an linear logistic regression. The risk factors of endometrial carcinoma including age of marriage, menopause, body mass index, exposure to X-ray, hypertension, pregnancies, and lactation were investigated. The results showed that body mass index, and exposure to X-ray were predominant risk factors; while pregnancies and lactation were protective factors.

Adult↗
PubMed1993

Estrogen receptor and progesterone receptor genes are expressed differentially in mouse embryos during preimplantation development.

Estrogen and progesterone play an important role in the development and implantation of preimplantation embryos. However, it is controversial whether these hormones act directly on the embryos. The effects of these hormones depend on the existence of their specific receptors. To determine whether estrogen receptor (ER) and progesterone receptor genes are expressed in mouse preimplantation embryos, we examined RNA from embryos at different stages of preimplantation development by reverse transcription-polymerase chain reaction techniques. ER mRNA was found in oocytes and fertilized eggs. The message level began to decline at the two-cell stage and reached its lowest level at the five- to eight-cell stage. ER mRNA was not detectable at the morula stage but reappeared at the blastocyst stage. Progesterone receptor mRNA was not detectable until the blastocyst stage. The embryonic expression of ER and progesterone receptor genes in the blastocyst suggests a possible functional requirement for ER and progesterone receptor at this stage of development. These results provide a basis for determining the direct role of estrogen and progesterone in preimplantation embryos.

Age Factors↗