The plasminogen-plasmin fibrinolytic system accelerates degradation of alginate-poly-L-lysine-alginate microcapsules in vitro.
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Alginates↗
Biomedical subjects
K S Chang
Publications and source records attributed to K S Chang.
A case of cor triatriatum in an eighty-year-old man: transesophageal echocardiographic observation of multiple defects.
An 80-year-old man was admitted to the hospital because of recurrent syncope caused by sick sinus syndrome. Conventional transthoracic echocardiography showed a membranelike echo-dense structure across the left atrium. Subsequently we confirmed the diagnosis of cor triatriatum with multiple defects and shunt flows across the membrane by transesophageal color flow Doppler echocardiography. There were no other associated congenital anomalies. The patient recovered well and was discharged from the hospital after implantation of a permanent VVI pacemaker for sinus node dysfunction. No other cardiac intervention for the cor triatriatum was done except follow-up with echocardiography. About 1 year after discharge, he died of massive cerebral infarction. The cardiac autopsy findings were compatible with the transesophageal echocardiogram. This is a rare case of uncorrected cor triatriatum in an elderly patient.
Aged↗
Stable overexpression of PML alters regulation of cell cycle progression in HeLa cells.
Our previous studies demonstrated that PML is a growth suppressor that suppresses oncogenic transformation of NIH/3T3 cells and rat embryo fibroblasts. PML is a nuclear matrix-associated phosphoprotein whose expression is regulated during the cell cycle. Disruption of PML function by t(15;17) in acute promyelocytic leukemia (APL) plays a critical role in leukemogenesis. To further study the role of PML in the control of cell growth, we have stably overexpressed PML protein in the HeLa cell line. This overexpression of PML significantly reduced the growth rate of HeLa cells and suppressed anchorage-independent growth in soft agar. We consequently investigated several parameters correlated with cell growth and cell cycle progression. We found that, in comparison with the parental HeLa cells, HeLa/PML stable clones showed proportionally more cells in G1 phase, fewer cells in S phase and about the same number in G2/M phase. The HeLa/PML clones showed a significantly longer doubling time as a result of a lengthening of the G1 phase. No effect on apoptosis was found in HeLa cells overexpressing PML. This observation indicates that PML suppresses cell growth by increasing cell cycle duration as a result of G1 elongation. To further understand the mechanism of the effect of PML on HeLa cells, expression of cell cycle-related proteins in HeLa/PML and parental HeLa cells was analyzed. We found that Rb phosphorylation was significantly reduced in PML stable clones. Expression of cyclin E, Cdk2 and p27 proteins was also significantly reduced. These studies indicate that PML affects cell cycle progression by mediating expression of several key proteins that normally control cell cycle progression. These results further extend our current understanding of PML function in human cells and its important role in cell cycle regulation.
CDC2-CDC28 Kinases↗
Further characterization of the binding properties of a GalNAc specific lectin from Codium fragile subspecies tomentosoides.
Previous study on the binding properties of a lectin isolated from Codium fragile subspecies tomentosoides (CFT) indicates that this lectin recognizes the GalNAc alpha1--> sequence at both reducing and nonreducing ends. In this study, the carbohydrate specificity of CFT was further characterized by quantitative precipitin (QPA) and inhibition of lectin-enzyme binding assays. Of the glycoforms tested for QPA, all asialo-GalNAc alpha1--> containing glycoproteins reacted well with the lectin. Asialo hamster and ovine submandibular glycoproteins, which contain almost exclusively Tn (GalNAc alpha1-->Ser/Thr) residues as carbohydrate side chains, and Streptococcus type C polysaccharide completely precipitated the lectin added, while the GalNAc beta1-->containing Tamm-Horsfall Sd(a+) glycoprotein and its asialo product were inactive. Among the oligosaccharides tested for inhibiting lectin-glycoprotein interaction, GalNAc alpha1-->3GalNAc beta1-->3Gal alpha1-->4Gal beta1--> 4Glc(Fp) and Gal beta1-->3GalNAc alpha1-->benzyl (T alpha) were the best, and about 125-fold more active than GalNAc. They were about 3.3, 6.6, and 43 times more active than Tn containing glycopeptides, GalNAc alpha1-->3(LFuc alpha1--> 2)Gal(Ah) and Gal beta1-->3GalNAc(T), respectively. From the present and previous results, it is concluded that the combining site of CFT is probably of a groove type that recognizes from GalNAc alpha1--> to pentasaccharide(Fp). The carbohydrate specificity of this lectin can be constructed and summarized in decreasing order by lectin determinants as follows: Fp and T alpha > Tn cluster > Ah >> I/II.
Acetylgalactosamine↗
Numerical analysis of three-dimensional Björk-Shiley valvular flow in an aorta.
Laminar vortical flow around a fully opened Björk-Shiley valve in an aorta is obtained by solving the three-dimensional incompressible Navier-Stokes equations. Used is a noniterative implicit finite-element Navier-Stokes code developed by the authors, which makes use of the well-known finite difference algorithm PISO. The code utilizes segregated formulation and efficient iterative matrix solvers such as PCGS and ICCG. Computational results show that the three-dimensional vortical flow is recirculating with large shear in the sinus region of the valve chamber. Passing through the valve, the flow is split into major upper and lower jet flows. The spiral vortices generated by the disk are advected in the wake and attenuated rapidly downstream by diffusion. It is shown also that the shear stress becomes maximum near the leading edge of the disk valve.
Algorithms↗
Transfer of the E6 and E7 genes of human papillomavirus type 18 into human epithelial cells via recombinant retrovirus infection.
A retroviral vector carrying the E6 and E7 genes of HPV type 18 was transfected into a packaging cell line, Ampho psi 2. Thirteen recombinant viruses carrying the E6 and E7 genes were obtained. The titers of these recombinant viruses were estimated by infecting BALB/c3T3 cells and then counting the number of G418r colonies. Presence of HPV E6/E7 genes was confirmed by the PCR method and sequence-specific primers. The expression of E7 gene was examined by RT-PCR method. Results showed that the titers were ranged between 0.2 and 1.2 x 10(3) CFU/ml and the E7 transcripts were detected in all 13 cell clones. These E6 and E7-containing cell clones were able to grow in soft agar, indicating the E6/E7 delivered by the recombinant retroviruses retained their transformation function. These recombinant viruses were then used to infect human NPC cell lines, NPC-TW076 and -TW039 and cell clones resistant to G418 were obtained. Using Western blot analysis and HPV type 18 E6-specific monoclonal antibody, HPV-CIP5, these cells were shown to contain a protein with a molecular mass of 18 kDa. Our data indicated that the HPV E6/E7-containing recombinant retroviruses were capable of infecting human cell lines. The potential of using these recombinant retroviruses to immortalize human primary epithelial cells was discussed.
3T3 Cells↗
Analysis of the growth and transformation suppressor domains of promyelocytic leukemia gene, PML.
The promyelocytic leukemia gene (PML) involved in the t(15;17) (q22;q12) translocation in acute promyelocytic leukemia is a growth suppressor. To elucidate the functional domains of PML, several mutants lacking the nuclear localization signal (PMLnls-), the dimerization domain (PMLdim-), the proline-rich domain at the N-terminal (PMLpro-), the proline-rich RING finger motif (PMLpr-), the proline-rich RING finger B-box-1 (PML-prb-), the serine-proline-rich domain at the C-terminal (PMLsp-), and the double mutant (PMLprb-nls-) have been constructed. Immunofluorescence staining of transiently transfected NIH3T3 cells demonstrated that the RING finger motif, dimerization domain, and nuclear localization signal are all required for the formation of PML oncogenic domains (PODs). Immunofluorescence staining of transiently transfected GM637D human fibroblasts indicated that expression of PMLprb-, PM-Lnls-, and PMLprb-nls- led to a significant reduction or, in some cases, complete elimination of PODs. PMLdim-, PMLnls-, PMLpr-, PMLprb-, and PMLprb-nls- mutants were found to lose their ability to suppress transformation of NIH3T3 cells by activated neu, while PMLpro- and PMLsp- mutants did not. These results suggest that the ability of PML to form a POD is essential for suppression of growth and transformation. Furthermore, since PMLprb-, PMLnls-, and PMLprb-nls- mutants could block the suppression effect of wild-type PML on transformation of NIH3T3 cells by the neu oncogene, these PML mutants are potential dominant negative inhibitors of PML. Our study also suggests that the RING finger motif may interact with other nuclear proteins.
3T3 Cells↗
Newly established MST-1 tumour cell line and tumour-infiltrating lymphocyte culture from a patient with soft tissue melanoma (clear cell sarcoma) and their potential applications to patient immunotherapy.
The establishment and characterisation of paired autologous tumour cell line (MST-1) and tumour-infiltrating lymphocyte (TIL) culture from a tumour mass of a 14-year-old Taiwanese girl with soft tissue melanoma are described. MST-1 cells grown in vitro were heterogeneous in morphology, ranging from floating round cells, loosely attached round/oval or elongated cells with prominent pseudopod-like processes, to well-attached spindle and elongated dendritic cells without obvious pseudopods. Immunostaining revealed that major melanoma-associated antigens, such as S100 protein, HMB-45, melanotransferrin, chondroitin sulphate proteoglycan, and the gangliosides GD2 and GD3, were consistently expressed by the tumour tissue, severe combined immunodeficiency (SCID) mouse xenograft and derived cell lines. Flow cytometric analysis of the tumour DNA content showed an index of 1.8 relative to normal peripheral blood lymphocyte DNA. Chromosome analysis revealed all cells at a hypotetraploid level with several clonal chromosome aberrations, including deletions at 10p and 12q, an addition at 12q, translocations t(1;14) and t(5;6). Electron microscopy showed melanosome structures. This observation and the expression of the major melanoma-associated antigens were all indicative of the melanocytic origin of MST-1 tumour. Interleukin-2 (IL-2) expanded TILs had the predominant CD8+ phenotype and the capacity to lyse cells of the cultured autologous tumour. The availability of the soft tissue melanoma cell line, the SCID mouse xenograft tumour system as well as autologous TILs described herein would provide useful materials for identifying T-cell-defined antigens as well as a model system for devising individualised cancer biotherapeutic strategies. This cell line can also be used for further studies aimed at uncovering the histogenesis of this rare cancer.
Adolescent↗
The effect of detector size to the broadening of the penumbra--a computer simulated study.
The effect of detector size to the broadening of the measured beam penumbra has been a subject of numerous studies. Based on measured data, linear and quadratic curves have been proposed to describe the relationship between the measured penumbra width, between 10%-90% and 20%-80% intensities, and the detector size. Extrapolations of these curves to zero detector size also suggest that the inherent penumbras can be deduced. However, due to experimental noise, especially when a small ionization chamber is used, and the inherent penumbra is not known, it is difficult to discern the superiority of either model. In this study, one dimensional convolution using a thin circular disk shape detector was employed to analyze the effect of detector size to the broadening of the penumbra. A set of beams with different inherent penumbra widths, ranging from 0 to 350 in arbitrary unit, was first generated. Each beam was then convoluted with the response function of the detectors with different sizes from 10 to 280, in arbitrary unit. The result is an output signal with penumbra that is wider than the inherent penumbra. The plots of penumbra widths to detector radii are a family of concave parabolic curves with different inherent penumbra widths. The concave portions of the curve represent results from scanning with detectors equal to or smaller than the penumbra width, and the linear portions represent results from scanning with detectors much larger than the penumbra. The curves are nothing but different scales of one curve. The extrapolations of the curves to the penumbra axis when the detector radius approaches zero give the deduced inherent penumbra widths. The deduced inherent penumbra widths approximate the inherent penumbra widths satisfactorily. From the graphs provided, the inherent penumbra can be deduced using the detector radius and the measured penumbra width.
Computer Simulation↗
Indigo carmine inhibits endothelium-dependent and -independent vasodilation.
To investigate the potential mechanisms by which indigo carmine produces hypertension, we tested the hypothesis that indigo carmine inhibits endothelium-dependent vasodilation and determined the possible site of the inhibition (endothelium versus smooth muscle). Using isolated rat thoracic aortic rings that were precontracted with phenylephrine, we examined vasodilatory responses to acetylcholine, histamine, and Ca2+ ionophore A23187 (in endothelium-intact rings) and sodium nitroprusside and isoproterenol (in endothelium-denuded rings) in the presence and absence of indigo carmine. In addition, the effects of methylene blue on the acetylcholine- and sodium nitroprusside-induced vasodilation were compared with those of indigo carmine. Indigo carmine (10(-6), 10(-5), and 10(-4) mol/L) significantly inhibited receptor- and non-receptor-mediated endothelium-dependent vasorelaxation. Indigo carmine (10(-4) mol/L) also inhibited endothelium-independent vasorelaxation induced by sodium nitroprusside (an activator of vascular smooth muscle soluble guanylyl cyclase), although to a lesser extent than vasodilation from acetylcholine, histamine, and Ca2+ ionophore A23187. In contrast, indigo carmine (10(-4) mol/L) had no effect on the vasodilation induced by isoproterenol (an activator of adenylyl cyclase), indicating that indigo carmine selectively inhibits nitric oxide-mediated responses. Methylene blue, a known inhibitor of soluble guanylyl cyclase, inhibited both acetylcholine- and sodium nitroprusside-induced vasorelaxation. The inhibition was also greater in the acetylcholine- than the sodium nitroprusside-induced vasodilation. These results suggest that indigo carmine, like methylene blue, may inhibit endothelium-dependent relaxation by a mechanism that involves two levels. The major action of indigo carmine appears to be at the level of nitric oxide generation and/or release from the endothelial cell. In addition, indigo carmine appears to inhibit vascular smooth muscle guanylyl cyclase. Thus, indigo carmine may elevate blood pressure by interfering with these nitric oxide-mediated vasodilatory mechanisms.
Acetylcholine↗
The biologic function of PML and its role in acute promyelocytic leukemia.
Patients with acute promyelocytic leukemia (APL) are characterized by the presence of a t(15;17) chromosomal translocation. The fusion protein PML-RAR alpha encoded from the breakpoint can form a heterodimer and acts as a dominant negative inhibitor against the normal function of PML. Recently we demonstrated that PML is a growth suppressor and transcription suppressor expressed in all cell lines tested. We also found that PML suppresses the clonogenicity and tumorigenicity of APL-derived NB4 cells, as well as the transformation of rat embryo fibroblasts by cooperative oncogenes and NIH/3T3 by neu. Overexpression of PML in human tumor cell lines induces a remarkable reduction in growth rate in vitro and in vivo. More recently, we have shown that PML is a phosphoprotein associated with the nuclear matrix and that its expression is cell cycle related. PML expression is altered during human oncogenesis, implying that PML may be an anti-oncogene involved not only in APL but also in other oncogenic events. Mutation analysis of the functional domains of PML demonstrated that its ability to form PML nuclear bodies or PODs (PML oncogenic domains) is essential for suppressing growth and transformation. In light of the above studies it appears that disruption of the normal function of PML plays a critical role in the pathogenesis of APL.
Animals↗
Tolazoline decreases survival time during microwave-induced lethal heat stress in anesthetized rats.
Effects of alpha-adrenergic antagonists have been studied during environmental heating but not during microwave-induced heating. Tolazoline may exert some of its effects via alpha-adrenegic blockade. In the present study, ketamine-anesthetized Sprague-Dawley rats were exposed to 2450-MHz microwaves at an average power density of 60 mW/cm2 (whole-body specific absorption rate of approximately 14 W/kg) until lethal temperatures were attained. The effects of tolazoline (10 mg/kg body weight) on physiological responses (including changes in body temperature, heart rate, blood pressure, and respiratory rate) were examined. Survival time was significantly shorter in the tolazoline group than in saline-treated animals. In general, heart rate and blood pressure responses were similar to those that occur during environmental heat stress. Heart rate, however, was significantly elevated in animals that received tolazoline, both before and during terminal microwave exposure. It is possible that changes associated with the elevated heart rate (e.g., less cardiac filling) in tolazoline-treated animals resulted in greater susceptibility to microwave-induced heating and the lower survival time.
Adrenergic alpha-Antagonists↗
Human foamy virus genome in the thymus of myasthenia gravis patients.
The etiological relationship of human foamy virus (HFV), which is a spumaretrovirus, with human diseases is not clear. We analyzed thymus specimens from four patients with myasthenia gravis for the presence of HFV proviral genome by polymerase chain reaction (PCR). The results showed the presence of both 257 base pair (bp) and 299 bp DNA fragments representing a part of gag and bel-2 sequences, respectively, in all four thymuses. Their specificity was confirmed by Southern blot hybridization with the corresponding probes. This was also confirmed by sequence analysis, although there were some point mutations. We confirmed the presence of gag related sequence, a 1353 bp Xba I-cleaved DNA fragment in all four thymus samples, a 693 bp fragment in two (#3 and #4) and a 4300 bp Hind III-cleaved DNA fragment in another two (#1 and #4), indicating possible chromosomal integration of the HFV partial genome. To our knowledge, this is the first report on the presence of HFV genome in thymus tissues of myasthenia gravis patients. Our efforts to isolate the infectious HFV by cultivation of the tissues were not successful. Low titers of neutralizing antibody were detected in all four patients' serum samples. The possible role of the HFV in this autoimmune disease needs further investigation.
Adult↗
Kidney transplantation from hepatitis B surface antigen (HBsAg)-positive donors: changes of relative HBV genomic copy number after transplantation.
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Adult↗
Increased invasive activity of human hepatocellular carcinoma cells is associated with an overexpression of thyroid hormone beta 1 nuclear receptor and low expression of the anti-metastatic nm23 gene.
To understand the role of thyroid hormone in metastasis, we studied the expression of the anti-metastatic nm23 gene in eight human hepatocellular carcinoma (HCC) cell lines. These cells differentially expressed the anti-metastatic nm23 gene. A low level of nm23 proteins was found to have a high in vitro invasive activity which correlated closely with an overexpression of the thyroid hormone beta 1 nuclear receptor (h-TR beta 1). Concurrent with the down-regulation of h-TR beta 1, the invasive activity of HCC cells was suppressed by the thyroid hormone, 3,3',5-triiodo-L-thyronine (T3). These results indicate that the invasive activity of HCC cells was regulated by T3, suggesting that T3 could be involved in modulating the functions of nm23.
Carcinoma, Hepatocellular↗
Binding studies on the combining site of a GalNAc alpha 1-->-specific lectin with Thomsen-Friedenreich activity prepared from green marine algae Codium fragile subspecies tomentosoides.
The combining site of a GalNAc alpha 1-->-specific lectin (CFT) with Thomsen-Friedenreich (T, Gal beta 1-->3-GalNAc alpha 1-->Ser/Thr) activity, purified from the subspecies tomentosoides of green marine algae Codium fragile was studied by quantitative precipitin and precipitin-inhibition assays. Of 27 glycoforms tested, Tn (GalNAc alpha 1-->Ser/Thr) glycoprotein from armadillo submandibular glands, and asialo porcine submandibular glycoprotein, which contains T, Tn and GalNAc alpha 1-->3Gal(A) sequences, completely precipitated the lectin added, and less than 1 microgram glycoprotein was required to precipitate 50% 4.7 micrograms lectin nitrogen. However, CFT precipitated negligibly with Pneumococcus type-XIV polysaccharide and asialo human alpha 1-acid glycoprotein, that contain exclusively the human blood-type-II precursor sequence (II, Gal beta 1-->4GlcNAc) at the nonreducing ends. Among the sugar inhibitors tested, the human blood A-active trisaccharide [Ah, GalNAc alpha 1-->3 (LFuc alpha 1-->2)Gal] was the best inhibitor; it was about twice as active as the T disaccharide. Oligosaccharides without GalNAc alpha 1--> as part of their sequences were inactive, indicating that the acetamido group at C2 of galactose is essential for binding and that GalNAc is the main contributor in the T sequence for binding. From the data provided, it is clear that the combining site of CFT requires an alpha-anomer of GalNAc and recognizes Ah, internal GalNAc alpha 1--> of T and Tn determinants of glycans, but not the blood group I/II (Gal beta 1-->3/4GlcNAc) sequences. Consequently, CFT is a useful reagent for detecting GalNAc alpha 1-->-containing glycoconjugates.
Acetylgalactosamine↗
Cytokine regulation of HIV-1 LTR transactivation in human hepatocellular carcinoma cell lines.
Human hepatocellular carcinoma (HCC) cell lines, HEP-G2, J5, and SK-HEP-1, which differ in their differentiation status, were compared for their trans-activating activities after treatment with cytokines or 12-O-tetradecanoylphorbol-13-acetate (TPA). These cells were transfected with a long terminal repeat (LTR) which was derived from human immunodeficiency virus type 1 (HIV-1) and ligated to chloramphenicol acetyl transferase (CAT) gene. After treatment with interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6), interferon-gamma (IFN-gamma), or TPA, they exhibited various degrees of enhancement of transactivation. The well differentiated HEP-G2 cells exhibited the highest degree of enhancement with these agents, while the poorly differentiated SK-HEP-1 cells showed no enhancement with cytokines and slight enhancement with TPA. The J5 cells, which were intermediate in their status of differentiation, showed a moderate degree of enhancement with cytokines and TPA. These results suggest that HCC cells at different stages of differentiation may produce different levels of cellular transacting factors activated by each of these agents. To map the cytokine response elements (CREs) in the HIV-1-LTR, HEP-G2 cells were transfected with nested series of 5' deletion mutants of HIV-1-LTR and treated with each of these cytokines. It was found that not only the degrees but also the patterns of enhancement varied depending upon the presence of positive or negative regulatory sequences in HIV-1-LTR, and that the NF-kappa B sequence played an important role, either by itself or in conjunction with the 5'-proximal response elements (REs) to interact with cellular trans-activating factors elicited by the cascade of transduction responses to cytokines. Despite the presence of promoters including kappa B and IFN-gamma RE as well as IL-6RE sequence in HIV-1-LTR-transfected cells, the poorly differentiated SK-HEP-1 cells showed no enhancement of transactivation by these cytokines, suggesting the lack of receptors or activity of some signal transduction factors which are present in well differentiated HEP-G2 and moderately differentiated J5 cells.
Amino Acid Sequence↗
The PML gene encodes a phosphoprotein associated with the nuclear matrix.
The t(15;17)(q22;q12) translocation is the cytogenetic hallmark of acute promyelocytic leukemia (APL). The PML and retinoic acid receptor-alpha (RAR alpha) transcription factor genes are involved at translocation breakpoint. To elucidate the biologic function of PML, antipeptide antibody against PML protein was raised in rabbits. This antibody was able to detect a 90-kD PML protein and a 110-kD PML-RAR alpha fusion protein by Western blotting and a nuclear speckled pattern in all cell lines by immunofluorescent staining. In K562 and NIH/3T3 cells transfected with a PML expression plasmid, we found PML to be associated with the nuclear matrix. Our results also showed that PML is a phosphorprotein. A weak signal was detected in a Western blot containing the immunoprecipitated PML protein using the phosphotyrosine-specific monoclonal antibody. Therefore, at least one of the sites was phosphorylated by a tyrosine kinase. From our analysis of the phosphoamino acids of the PML protein by complete hydrolysis and thin-layer chromatography, we concluded that both tyrosine and serine residues of PML are phosphorylated. To investigate whether expression of the PML protein is cell-cycle related, HeLa cells synchronized at various phases of the cell cycle were analyzed by immunofluorescence staining and confocal microscopy for PML expression. We found that PML was expressed at a lower level in S, G2, and M phases and at a significantly higher level in G1 phase. Our study showed that PML has many similar properties compared with the tumor suppressor, eg, Rb. These findings further support the important role of PML in APL pathogenesis.
3T3 Cells↗