Biomedical subjects

P Hou

Publications and source records attributed to P Hou.

25 records · Page 2Linked to original sources

PubMed1996

Quantification of the collagenolytic activity of isolated osteoclasts by enzyme-linked immunosorbent assay.

Difficulties in the geometrical definition and measurement of resorption pits is a major problem for the quantitative analysis of bone resorption by isolated osteoclasts cultured on bone or dentin substrates. In this study we developed an enzyme-linked immunosorbent assay (ELISA) for quantification of bone resorption in vitro, which specifically quantifies type I collagen fragments released into the culture medium by the resorptive action of bone cells cultured on slices of bone or dentin. A consistently high correlation between the formation of resorption pits and the release of antigenic collagen fragments was observed for isolated rabbit osteoclasts seeded at various densities and cultured for various periods on bovine, elephant, and human substrates. In a further support of the osteoclastic nature of the collagenolytic effects, a high consistency between pit formation and collagenolysis was also observed when the rabbit bone cells were cultured in the presence of very differently acting but typical inhibitors of pit formation, i.e., the carbonic anhydrase inhibitor acetazolamide, the cysteine proteinase inhibitor epoxysuccinyl-L-leucylamido-(4-guanodino)butane (E-64), the phosphatidyl-inositol 3-kinase inhibitor wortmannin, and the bisphosphonate ibandronate (BM 21.0955). In conclusion, the ELISA represents a simple, precise, and objective way to dynamically monitor bone resorption in vitro through quantification of the collagenolytic activity of isolated osteoclasts.

Amino Acid Sequence↗

PubMed1996

[Loss of CDKN2 gene and amplification of cyclin D1 gene in human esophageal cancer].

The products of both CDKN2 and cyclin D1 genes are negative and positive regulators respectively in cell cycle. To study the involvement of the CDKN2 tumor suppressor gene and cyclin D1 oncogene in esophageal cancer development, we examined the situation of both genes in 21 pairs of primary human esophageal cancers and the mucosa adjacent to the cancers and also in four esophageal cancer cell lines by means of molecular biological and immunohistochemical techniques. Homozygous deletion was observed in 6 out of the 21 primary cancers and with lymph node metastasis in 5 out of the 6 cases. Loss of expression of p16 protein was identified immunohistochemically in 8 out of 21 primary cancers. Amplification of cyclin D1 was found in 12 out of 21 primary cancers and in 5 esophageal mucosa adjacent to the tumors, accompanying with overexpression of cyclin D1 protein. Homozygous deletion was observed in one (EC8712) out of the four cell lines, while by Northern and immunohisto chemistry analysis, loss of transcription of CDKN2 mRNA and loss of p16 protein expression were observed in two cell lines (EC8712 and EC8501). Amplification and overexpression of cyclin D1 were found in two cell lines (EC8733 and EC8501). These findings suggest that loss of CDKN2 gene and amplification of cyclin D1 gene are involved in esophageal cancers and that cyclin D1 alteration may be a earlier molecular event while CDKN2 to be a later one.

Carcinoma, Squamous Cell↗

PubMed1996

[Studies of the characteristic features of Ki-1 positive non-Hodgkin's lymphoma].

The clinical histopathological and immunophenotypic features in 5 patients with Ki-1 positive non-Hodgkin's lymphoma (NHL) were studied. When first seen, 4 patients presented enlargement of superficial lymph nodes, with skin lesions in 2 patients. Two patients in stage IV with fever, hepato-splenomegaly and bone marrow invasion, died. Histologically, the tumor cells showed diffused or patchy hyperplasia. The cells were relatively large in size, rich in bosophilic or slightly eosinophilic cytoplasm with irregularly-shaped nuclei, prominent nucleoli, and distinct anaplasia and pleomorphism. Some of the cells looked very much like the Reed-Sternberg cells. Multinucleated giant cells were seen. Immunophenotypically, all the cells were CD30 (Ki-1) and CD25 (IL-2 receptor) positive but CD15 (Leu M1) negative. Thus, the 5 patient T Ki-1 positive NHL were all of T cell type.

Adolescent↗

PubMed1991

Hybrid MR angiography and Fourier velocity imaging using two echo 3D acquisition.

Fourier velocity imaging can be accomplished without cardiac gating from the second echo of a standard 3D MR angiography sequence. The stepped bipolar velocity encoding gradient is obtained by adding a gradient pulse opposite in area to the spatial phase encoding gradient. In this technique, Fourier images of three spatial coordinates are obtained from the first echo and images of two spatial coordinates and one velocity component are obtained from the second echo.

Blood Flow Velocity↗

PubMed1988

Changes in various parameters of fibrinolysis in persons infused with tissue plasminogen activator: special reference to plasminogen activator inhibitor.

Tissue plasminogen activator (t-PA) purified from culture of human lung cells was infused over 30 min at the dose of 7.2 mg or 14.4 mg per person into human male volunteers. T-PA declined rapidly after the cessation of infusion with T1/2, alpha of about 4 min and T1/2, beta of about 40 min. The plasma fibrinogen and plasminogen did not change during and after the infusion of t-PA. The concentration of alpha 2antiplasmin (alpha 2AP) did not change but that of alpha 2AP-plasmin complex increased to about 200 nM at the infusion of 14.4 mg/person. Fragment D was hardly found at the infusion of 7.2 mg but some increase in the concentration of D was observed at the infusion of 14.4 mg. The concentration of free plasminogen activator inhibitor (PAI-1) rapidly declined and kept low up to 150 min, and returned to normal the following day. The concentration of t-PA-PAI-1 complex increased rapidly, and slowly declined after the end of the infusion of t-PA, suggesting no significant release of PAI-1 in response to increase in plasma concentration of t-PA or t-PA-PAI-1 complex. The addition of thrombin to the blood after withdrawal resulted in the significant formation of D-dimer, even at 150 min after the infusion. There was not hyperaggregability of platelets during and after the infusion of t-PA. These results suggest that the infusion of t-PA at the dose of 7.2 mg or 14.4 mg/person for 30 min resulted in high fibrinolytic potential in the blood without the breakdown of fibrinogen or increase in PAI-1.

Adult↗

PubMedDate not supplied

Synergistic antitumor effect of tumor necrosis factor-related apoptosis-inducing ligand combined with cisplatin in ovarian carcinoma cell lines in vitro and in vivo.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to exert selectively cytotoxic activity against many tumor cells but not normal cells. In this study, we evaluated the antitumor activity of TRAIL and cisplatin (CDDP) both separately and combined in the human ovarian cancer cell lines. In vitro study showed that TRAIL elicited significant cell apoptosis of cell lines 3AO, SKOV3, and OVCAR3 in a dose- and time-dependent manner (P < 0.05), while normal ovarian epithelial cells were resistant; this toxicity-free effect may be the result of upregulation of TRAIL receptors DcR1 and DcR2. Combined TRAIL and CDDP therapy produced more profound cell killing in 3AO cells than each alone (P < 0.05), and CDDP could upregulate the expression of both death and decoy TRAIL receptors. To further evaluate the apoptosis-inducing effects of TRAIL and the combination therapy, the abdominally and subcutaneously spread tumors in nude mice via inoculation of 3AO cells were established, and treatment of TRAIL resulted in a dose- and time-dependent inhibition of tumor growth while slight damage was observed in normal tissues. Furthermore, combined TRAIL and CDDP therapy had a synergistic effect in the regression of established ovarian cancer xenografts than TRAIL treatment alone (P < 0.05). We also examined the apoptosis-related gene expression in the transplantation tumors after TRAIL treatment, and the data suggested that the intracellular mechanism of TRAIL may be associated with downregulation of Bcl-2 and upregulation of CD95 and Apo2.7.

Adenocarcinoma, Mucinous↗

PubMedDate not supplied

Fat suppression in combination with multiple overlapping thin-slab 3-D acquisition MR angiography: proposed technique for improved vessel visualization.

PURPOSE: To study the parameters of the 1331 fat saturation pulse (saturation pulse flip angle (SPFA) and interpulse delay (tau)) in order to identify values that provide optimal vessel visibility. METHODS: Carotid bifurcations of three healthy subjects were studied. RESULTS: The optimal values for the SPFA and tau were 60 degrees (7.5 degrees, -22.5 degrees, 22.5 degrees, -7.5 degrees) and 2.0-3.0 msec, respectively. At these values there was a 1.56-fold increase (SD = +/- .12, P less than .01) in the contrast-to-noise ratio between the left internal carotid artery and fat compared to the study without fat saturation. A 3.0-fold increase was noted for the smaller left occipital artery. Additionally, there was no statistically significant reduction in the vessel-muscle contrast-to-noise ratio nor in the absolute vessel signal-to-noise ratio at these values. CONCLUSION: Implementation of fat saturation into carotid MR angiography markedly improves visualization of vascular anatomy without increasing imaging time.

Adipose Tissue↗