New improved sternal bands--a biomechanical analysis.
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Cardiac Surgical Procedures↗
Biomedical subjects
L Yang
Publications and source records attributed to L Yang.
Oxidative stability of conjugated linoleic acid isomers.
Conjugated linoleic acids (CLAs) have been shown to be a strong anticarcinogen in a number of animal models. Our previous study demonstrated that CLA as a whole was extremely unstable in air. The present study was undertaken further to examine the oxidative stability of individual CLA isomers using the combination of gas-liquid chromatography (GLC) and silver ion high-performance liquid chromatography (Ag-HPLC). It was found that CLA as a whole oxidized rapidly and more than 80% was degraded within 110 h in air at 50 degrees C. Four c,c-CLA isomers were most unstable followed by four c,t-CLA isomers. In contrast, four t,t-CLA isomers were relatively stable under the same experimental conditions. Both the oxygen consumption and the GLC analysis revealed that 200 ppm jasmine green tea catechins (GTCs) exhibited protection to CLA and were even stronger than 200 ppm butylated hydroxytoluene (BHT) when added to either CLA or canola oil containing 10% CLA. The present study emphasized that oxidative unstability of CLA should not be overlooked although CLA has many biological effects.
Antioxidants↗
Formation of functional tissue from transplanted adrenocortical cells expressing telomerase reverse transcriptase.
We report the first use of human telomerase reverse transcriptase (hTERT) expression in experimental xenotransplantation. Previously, we showed that bovine adrenocortical cells can be transplanted into severe combined immunodeficient (SCID) mice, and that these cells form functional tissue that replaces the animals' own adrenal glands. We cotransfected primary bovine adrenocortical cells with plasmids encoding hTERT, SV40 T antigen, neo, and green fluorescent protein. These clones do not undergo loss of telomeric DNA and appear to be immortalized. Two clones were transplanted beneath the kidney capsule of SCID mice. Animals that received cell transplants survived indefinitely despite adrenalectomy. The mouse glucocorticoid, corticosterone, was replaced by the bovine glucocorticoid, cortisol, in the plasma of these animals. The tissue formed from the transplanted cells resembled that formed by transplantation of cells that were not genetically modified and was similar to normal bovine adrenal cortex. The proliferation rate in tissues formed from these clones was low and there were no indications of malignant transformation.
Adrenal Cortex↗
Identification of a previously unknown antigen-specific regulatory T cell and its mechanism of suppression.
Despite increasing evidence for the existence of antigen-specific regulatory T cells, the mechanisms underlying suppression remain unclear. In this study we have identified and cloned a novel subset of antigen-specific regulatory T cells and demonstrated that these T cells possess a unique combination of cell surface markers and array of cytokines. The regulatory T cells are able to inhibit the function of T cells carrying the same T-cell receptor specificity and prevent skin allograft rejection in an antigen-specific, dose-dependent manner. The regulatory T cells are able to acquire alloantigen from antigen-presenting cells, present the alloantigen to activated syngeneic CD8+ T cells and then send death signals to CD8+ T cells. These findings provide a novel mechanism of regulatory T-cell-mediated, antigen-specific suppression.
Animals↗
Immunotherapy of tumors with xenogeneic endothelial cells as a vaccine.
The breaking of immune tolerance against autologous angiogenic endothelial cells should be a useful approach for cancer therapy. Here we show that immunotherapy of tumors using fixed xenogeneic whole endothelial cells as a vaccine was effective in affording protection from tumor growth, inducing regression of established tumors and prolonging survival of tumor-bearing mice. Furthermore, autoreactive immunity targeting to microvessels in solid tumors was induced and was probably responsible for the anti-tumor activity. These observations may provide a new vaccine strategy for cancer therapy through the induction of an autoimmune response against the tumor endothelium in a cross-reaction.
Amino Acid Sequence↗
In vitro stability of recombinant human factor VIII (Recombinate).
Factor VIII (FVIII) is currently administered in diverse settings and by a range of methods, and it is important that the stability of specific FVIII preparations be documented for these varying uses. This study of Recombinate recombinant human FVIII (rhFVIII) evaluated: (i) thermostability; (ii) photostability; (iii) stability during simulated continuous infusion; and (iv) stability after dilution. This evaluation was conducted over a range of initial rhFVIII potencies and under differing conditions of temperature, light exposure, dilution and heparin usage. FVIII biological activity was measured by one-stage and chromogenic substrate assays. Microbiological assessment was also performed. Lyophilized rhFVIII was found to be highly thermostable, as evidenced by an energy of activation (Ea) of 16.2 kcal mol-1 and recovery of 99.3% of initial activity after incubation for 6 months at 40 degrees C and 93.8% at 60 degrees C for 2 months. No significant loss of activity could be detected after accelerated simulated natural daylight exposure of lyophilized rhFVIII, although partial activity loss was observed after similar exposure of reconstituted rhFVIII. Shielding in foil wrap effectively prevented such photodegradation of reconstituted rhFVIII. Based upon these results, exposure of lyophilized rhFVIII to sunlight is unlikely to affect stability adversely. Activity of reconstituted rhFVIII (22-106 IU mL-1) remained stable during simulated continuous infusion for 96 h at ambient (20-25 degrees C) and elevated (28-32 degrees C) temperature, and in the presence or absence of 1 U mL-1 heparin. After dilution of reconstituted rhFVIII, an immediate 14-42% loss of expected rhFVIII activity was observed depending upon diluent composition. Accordingly, potential partial loss of rhFVIII activity should be taken into account when dilution is being considered. rhFVIII remained sterile at least 96 h during simulated continuous infusion. rhFVIII is a robust preparation exhibiting biological stability under a wide array of clinically relevant conditions.
Bacteria↗
Eremophilenolides from Ligularia fischeri.
The chemical investigation of Ligularia fischeri afforded three new eremophilenolides which were identified as 6 beta-methoxy-8 beta-hydroxy-eremophil-7(11)-en-12,8 alpha-olide, ligufischerin, and 6-oxo-8 beta-hydroxy-eremophil-7(11)-en-12,8 alpha-olide by 1D- and 2D-NMR spectra. In addition, six known eremophilenolides were also obtained.
Asteraceae↗
Terpenoids and flavonoids from Artemisia species.
A phytochemical reinvestigation of the aerial parts of Artemisia sieversiana gave a new guaianolide and two known flavones (chrysosplenetin and 5-hydroxy-3',4',6,7-tetramethoxyflavone). Antifungal fractions derived from the chloroform extract of A. annua afforded two cadinane derivatives (arteannuin B and artemisinin), oleanolic acid, beta-sitosterol, stigmasterol, and the four flavones artemetin, bonanzin, eupalitin and chrysosplenetin. Their structures were elucidated by spectral methods. All isolates from the two species were tested in vitro for antifungal activity. Arteannuin B, a main sesquiterpenoid in A. annua, showed antifungal activity against one human (Candida albicans, MIC: 100 micrograms/ml) and four plant pathogenic fungi (Gaeumannomyces graminis var. tritici, Rhizoctonia cerealis, Gerlachia nivalis and Verticillium dahliae, MICs: 150, 100, 150 and 100 micrograms/ml, respectively) whereas others showed no antifungal activity. The MIC value of ketoconazole to C. albicans was 1.0 microgram/ml, and those of triadimefon to G. graminis var. tritici and R. cerealis 150 and 100 micrograms/ml.
Antifungal Agents↗
Aquaticol, a bis-sesquiterpene and iridoid glucosides from Veronica anagallis-aquatica.
Aquaticol, an unusual bis-sesquiterpene was isolated from the medicinal plant Veronica anagallis-aquatica, in addition to 11 known compounds, aucubin, geniposidic acid, mussaenoside, catalposide, verproside, amphicoside, catalpol, boschnaloside, shanzhiside methyl ester, sitosterol and beta-stigmast-4-en-6 beta-ol-3-one. The structure of aquaticol was determined by spectroscopic means and by X-ray crystallographic analysis.
Molecular Structure↗
Eotaxin induces a sustained reduction in the functional adhesive state of very late antigen 4 for the connecting segment 1 region of fibronectin.
BACKGROUND: Eosinophils that have bound to extracellular matrix proteins, such as the connecting segment 1 (CS-1) region of fibronectin, need to deadhere before undergoing chemotaxis through the extracellular matrix. OBJECTIVE: We have investigated whether eotaxin can regulate the strength of eosinophil adhesion to the CS-1 region of fibronectin. METHODS: We have used a micropipette single-cell adhesion assay to determine the force of eosinophil adhesion to the CS-1 region of fibronectin. RESULTS: Eosinophils bound to CS-1 with high avidity, and this binding could be inhibited with neutralizing antibodies to alpha4 integrins expressed by eosinophils or with neutralizing antibodies to CS-1. Eosinophils incubated in the presence of eotaxin demonstrated a transient increase in the force of eosinophil adhesion to CS-1, which was followed by a more sustained reduction in the force of eosinophil adhesion to CS-1, as assessed in the micropipette single-cell adhesion assay. This decreased binding of eosinophils to CS-1 was not due to alterations in very late antigen 4 (VLA-4) receptor number, as assessed with FACS analysis, or alterations in VLA-4 receptor distribution, as assessed with immunofluorescence microscopy. CONCLUSIONS: These studies suggest that eotaxin can cause a transient increase followed by a more sustained reduction in the functional force of VLA-4 adhesion to CS-1 and thus promote deadhesion of CS-1 adherent eosinophils in the extracellular matrix.
Antigens, CD↗
Interaction of the tau2 transcriptional activation domain of glucocorticoid receptor with a novel steroid receptor coactivator, Hic-5, which localizes to both focal adhesions and the nuclear matrix.
Hic-5 (hydrogen peroxide-inducible clone-5) is a focal adhesion protein that is involved in cellular senescence. In the present study, a yeast two-hybrid screen identified Hic-5 as a protein that interacts with a region of the glucocorticoid receptor that includes a nuclear matrix-targeting signal and the tau2 transcriptional activation domain. In transiently transfected mammalian cells, overexpression of Hic-5 potentiated the activation of reporter genes by all steroid receptors, excluding the estrogen receptor. The activity of the estrogen receptor and the thyroid hormone receptor was stimulated by Hic-5 in the presence but not in the absence of coexpressed coactivator GRIP1. In biochemical fractionations and indirect immunofluorescence assays, a fraction of endogenous Hic-5 in REF-52 cells and transiently expressed Hic-5 in Cos-1 cells was associated with the nuclear matrix. The C-terminal region of Hic-5, which contains seven zinc fingers arranged in four LIM domains, was required for interaction with focal adhesions, the nuclear matrix, steroid receptors, and the tau2 domain of glucocorticoid receptor. The N-terminal region of Hic-5 possesses a transcriptional activation domain and was essential for the coactivator activity of Hic-5. Given the coexisting cytoplasmic and nuclear distributions of Hic-5 and its role in steroid receptor-mediated transcriptional activation, it is proposed that Hic-5 might transmit signals that emanate at cell attachment sites and regulate transcription factors, such as steroid receptors.
Animals↗
Oscillatory clusters in a model of the photosensitive belousov-zhabotinsky reaction system with global feedback
Oscillatory cluster patterns are studied numerically in a reaction-diffusion model of the photosensitive Belousov-Zhabotinsky reaction supplemented with a global negative feedback. In one- and two-dimensional systems, families of cluster patterns arise for intermediate values of the feedback strength. These patterns consist of spatial domains of phase-shifted oscillations. The phase of the oscillations is nearly constant for all points within a domain. Two-phase clusters display antiphase oscillations; three-phase clusters contain three sets of domains with a phase shift equal to one-third of the period of the local oscillation. Border (nodal) lines between domains for two-phase clusters become stationary after a transient period, while borders drift in the case of three-phase clusters. We study the evolving border movement of the clusters, which, in most cases, leads to phase balance, i.e., equal areas of the different phase domains. Border curling of three-phase clusters results in formation of spiral clusters-a combination of a fast oscillating cluster with a slow spiraling movement of the domain border. At higher feedback coefficient, irregular cluster patterns arise, consisting of domains that change their shape and position in an irregular manner. Localized irregular and regular clusters arise for parameters close to the boundary between the oscillatory region and the reduced steady state region of the phase space.
Journal Article↗
Trans-regulated silencing and reactivation of TP53 tumor suppressor gene in malignant transformation and its reversion.
Despite growing interest in the methylation-mediated silencing of tumor suppressor genes in the neoplastic process, its signaling mechanism remains largely unknown. Here we show in a cultured murine cell line system that the silencing and reactivation of tumor suppressor gene TP53 were reversibly controlled by a trans-acting regulatory mechanism. The gene product p53, which was constitutively expressed and activated upon X-ray irradiation in non-malignant parental cell line, was undetectable in its X-ray-induced malignant transformants, while they retained a wild-type TP53. The silencing was cancelled by transferring a human chromosome 11 and the expression of p53 was restored. The non-malignant revertants thus obtained were again susceptible to transformation by X-irradiation, giving rise to re-transformants, in which p53 was again repressed while the human chromosome 11 retained the ability to turn on TP53 when it was transferred into other malignant clone. The silent TP53 could be reactivated by treatment with the demethylating agent 5-azadeoxycytidine. These observations indicate the presence of a trans-acting signaling mechanism in the methylation-mediated regulation of TP53 expression which is associated with the acquisition of malignancy.
Animals↗
Valproate prevents epileptiform activity after trauma in an in vitro model in neocortical slices.
PURPOSE: Epileptogenesis is a hallmark of severe cortical trauma, with up to approximately 80% of patients experiencing seizures in the first 24 hours after penetrating head injury. An in vitro model of traumatic brain injury was developed to investigate hyperexcitability and epileptogenesis and their prevention. We determined whether sodium valproate would prevent epileptiform activity in this experimental model. METHODS: Rat cortical slices were prepared and maintained in vitro using standard methods. Trauma was effected by removing the superficial 450-500 microm of slices. Traumatized slices were exposed to valproate at various time points. Intracellular and extracellular recordings were used to assess evoked activities. RESULTS: In untreated traumatized deep segments, hyperexcitability was manifested by depressed inhibition and often (54%) by epileptiform activity. Preparations exposed to valproate at 30 minutes or later after trauma showed abnormal activity similar to control traumatized slices. Epileptogenicity in deep segments was significantly reduced when slices were exposed to valproate (a) continuously immediately after trauma, (b) after a 20-minute delay, or (c) immediately after trauma for 1 hour and then returned to physiological solution. Finally, slices that were exposed to valproate or pentobarbital beginning 20 minutes after trauma for only 1 hour and then returned to physiological medium showed a significant reduction in abnormal activity. Valproate was found to enhance fast gamma-aminobutyric acid(A)-ergic inhibitory strength. CONCLUSIONS: Valproate significantly reduces epileptiform activity after trauma to the neocortex, likely by restoring the excitation-inhibition balance, perhaps through augmentation of gamma-aminobutyric acid transmission. The timing of this action may have implications for mechanisms of seizure genesis and may suggest a role for rapid treatment.
Animals↗
Immunohistochemical analysis of primary sensory neurons latently infected with herpes simplex virus type 1.
We characterized the populations of primary sensory neurons that become latently infected with herpes simplex virus (HSV) following peripheral inoculation. Twenty-one days after ocular inoculation with HSV strain KOS, 81% of latency-associated transcript (LAT)-positive trigeminal ganglion (TG) neurons coexpressed SSEA3, 71% coexpressed Trk(A) (the high-affinity nerve growth factor receptor), and 68% coexpressed antigen recognized by monoclonal antibody (MAb) A5; less than 5% coexpressed antigen recognized by MAb KH10. The distribution of LAT-positive, latently infected TG neurons contrasted sharply with (i) the overall distribution of neuronal phenotypes in latently infected TG and (ii) the neuronal distribution of viral antigen in productively infected TG. Similar results were obtained following ocular and footpad inoculation with KOS/62, a LAT deletion mutant in which the LAT promoter is used to drive expression of the Escherichia coli lacZ gene. Thus, although all neuronal populations within primary sensory ganglia appear to be capable of supporting a productive infection with HSV, some neuronal phenotypes are more permissive for establishment of a latent infection with LAT expression than others. Furthermore, expression of HSV LAT does not appear to play a role in this process. These findings indicate that there are marked differences in the outcome of HSV infection among the different neuronal populations in the TG and highlight the key role that the host neuron may play in regulating the repertoire of viral gene expression during the establishment of HSV latent infection.
Animals↗
CD21-mediated entry and stable infection by Epstein-Barr virus in canine and rat cells.
We developed an adenovirus vector for transduction of the human CD21 gene (Adv-CD21), the Epstein-Barr virus (EBV)-specific receptor on human B lymphocytes, to overcome the initial barrier of EBV infection in nonprimate mammalian cells. Inoculation of Adv-CD21 followed by exposure to recombinant EBV carrying a selectable marker resulted in the successful entry of EBV into three of seven nonprimate mammalian cell lines as evidenced by expression of EBV-determined nuclear antigen (EBNA). The EBV-susceptible cell lines included rat glioma-derived 9L, rat mammary carcinoma-derived c-SST-2, and canine kidney-derived MDCK. Subsequent selection culture with G418 yielded drug-resistant cell clones. In these cell clones, EBV existed as an episomal form, as evidenced through the Gardella gel technique. Among the known EBV latency-associated gene products, EBV-encoded small RNAs, EBNA1 and transcripts from the BamHI-A rightward reading frame (BARF0), and latent membrane protein 2A were expressed in all EBV-infected cell clones. The viral lytic events could be induced in these cell clones by simultaneous treatment with 12-O-tetradecanoylphorbol-13-acetate and n-butyric acid, but they were abortive, and infectious virus was not produced. These results indicate that once the initial barrier for attachment is overcome artificially, EBV can establish a stable infection in some nonprimate mammalian cells, and they raise the possibility that transgenic animals with the human CD21 gene could provide an animal model for EBV infection.
Adenoviridae↗
Evidence for a bidirectional element located downstream from the herpes simplex virus type 1 latency-associated promoter that increases its activity during latency.
Herpes simplex virus type 1 (HSV-1) latent infection in vivo is characterized by the constitutive expression of the latency-associated transcripts (LAT), which originate from the LAT promoter (LAP). In an attempt to determine the functional parts of LAP, we previously demonstrated that viruses harboring a DNA fragment 3' of the LAT promoter itself were able to maintain detectable promoter expression throughout latency whereas viruses not containing this element could not (J. R. Lokensgard, H. Berthomme, and L. T. Feldman, J. Virol. 71:6714-6719, 1997). This element was therefore called a long-term expression element (LTE). To further study the role of the LTE, we constructed plasmids containing a DNA fragment encompassing the LTE inserted into a synthetic intron between the reporter lacZ gene and either the LAT or the HSV-1 thymidine kinase promoter. Transient-expression experiments with both neuronal and nonneuronal cell lines showed that the LTE locus has an enhancer activity that does not activate the cytomegalovirus enhancer but does activate the promoters such as the LAT promoter and the thymidine kinase promoter. The enhancement of these two promoters occurs in both neuronal and nonneuronal cell lines. Recombinant viruses containing enhancer constructs were constructed, and these demonstrated that the enhancer functioned when present in the context of the viral DNA, both for in vitro infections of cells in culture and for in vivo infections of neurons in mouse dorsal root ganglia. In the infections of mouse dorsal root ganglia, there was a very high level of promoter activity in neurons infected with viruses bearing the LAT promoter-enhancer, but this decreased after the first 2 or 3 weeks. By 18 days postinfection, neurons harboring latent virus without the enhancer showed no beta-galactosidase (beta-gal) staining whereas those harboring latent virus containing the enhancer continued to show beta-gal staining for long periods, extending to at least 6 months postinfection, the longest time examined.
Animals↗
TLS-ERG leukemia fusion protein inhibits RNA splicing mediated by serine-arginine proteins.
The translocation liposarcoma (TLS) gene is fused to the ETS-related gene (ERG) in human myeloid leukemia, resulting in the generation of a TLS-ERG protein. We demonstrate that both TLS and the TLS-ERG leukemia fusion protein bind to RNA polymerase II through the TLS N-terminal domain, which is retained in the fusion protein; however, TLS recruits members of the serine-arginine (SR) family of splicing factors through its C-terminal domain, whereas the TLS-ERG fusion protein lacks the ability to recruit SR proteins due to replacement of the C-terminal domain by the fusion partner ERG. In transient-transfection assays, the TLS-ERG fusion protein inhibits E1A pre-mRNA splicing mediated by these TLS-associated SR proteins (TASR), and stable expression of the TLS-ERG fusion protein in K562 cells alters the splicing profile of CD44 mRNA. These results suggest that TLS fusion proteins may lead to cellular abnormalities by interfering with the splicing of important cellular regulators.
Adenovirus E1A Proteins↗