Characterization of gas and particle emission from smoldering incenses with various diameters.
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Air Pollutants↗
Biomedical subjects
T T Yang
Publications and source records attributed to T T Yang.
Effect of air flow on emission of smoldering incense.
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Air Movements↗
Comparison of fMRI activation at 3 and 1.5 T during perceptual, cognitive, and affective processing.
Previous studies comparing fMRI data acquired at 1.5 T and higher field strengths have focused on examining signal increases in the visual and motor cortices. No information is, however, available on the relative gain, or the comparability of data, obtained at higher field strengths for other brain regions such as the prefrontal and other association cortices. In the present study, we investigated fMRI activation at 1.5 and 3 T during visual perception, visuospatial working memory, and affect-processing tasks. A 23% increase in striate and extrastriate activation volume was observed at 3 T compared with that for 1.5 T during the visual perception task. During the working memory task significant increases in activation volume were observed in frontal and parietal association cortices as well as subcortical structures, including the caudate, globus pallidus, putamen, and thalamus. Increases in working memory-related activation volume of 82, 73, 83, and 36% were observed in the left frontal, right frontal, left parietal, and right parietal lobes, respectively, for 3 T compared with 1.5 T. These increases were characterized by increased activation at 3 T in several prefrontal and parietal cortex regions that showed activation at 1.5 T. More importantly, at 3 T, activation was detected in several regions, such as the ventral aspects of the inferior frontal gyrus, orbitofrontal gyrus, and lingual gyrus, which did not show significant activation at 1.5 T. No difference in height or extent of activation was detected between the two scanners in the amygdala during affect processing. Signal dropout in the amygdala from susceptibility artifact was greater at 3 T, with a 12% dropout at 3 T compared with a 9% dropout at 1.5 T. The spatial smoothness of T2* images was greater at 3 T by less than 1 mm, suggesting that the greater extent of activation at 3 T beyond these spatial scales was not due primarily to increased intrinsic spatial correlations at 3 T. Rather, the increase in percentage of voxels activated reflects increased sensitivity for detection of brain activation at higher field strength. In summary, our findings suggest that functional imaging of prefrontal and other association cortices can benefit significantly from higher magnetic field strength.
Adolescent↗
Human mesenchymal tumour-associated macrophages differentiate into osteoclastic bone-resorbing cells.
The cellular mechanisms which account for the formation of osteoclasts and bone resorption associated with enlarging benign and malignant mesenchymal tumours of bone are uncertain. Osteoclasts are marrow-derived, multinucleated, bone-resorbing cells which express a macrophage phenotype. We have determined whether tumour-associated macrophages (TAMs) isolated from benign and malignant mesenchymal tumours are capable of differentiating into osteoclasts. Macrophages were cultured on both coverslips and dentine slices for up to 21 days with UMR 106 osteoblastic cells in the presence of 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) and human macrophage colony-stimulating factor (M-CSF) or, in the absence of UMR 106 cells, with M-CSF and RANK ligand. In all tumours, the formation of osteoclasts from CD14-positive macrophages was shown by the formation of tartrate-resistant-acid-phosphatase and vitronectin-receptor-positive multinucleated cells which were capable of carrying out lacunar resorption. These results indicate that the tumour osteolysis associated with the growth of mesenchymal tumours in bone is likely to be due in part to the differentiation of mononuclear phagocyte osteoclast precursors which are present in the TAM population of these lesions.
Animals↗
Drug delivery performance of the mometasone furoate dry powder inhaler.
The mometasone furoate dry powder inhaler (MF-DPI) is a multiple-dose, breath-actuated inhaler that uses agglomerates of micronized MF and lactose. In vitro analyses evaluated dose uniformity, variability, and particle size distribution of the MF-DPI. Tests of first, middle, and end doses from 10 inhalers each of the 200-microg MF/inhalation and 400-microg MF/inhalation dose sizes found that delivered doses (doses emitted from the inhaler) ranged from 91% to 112% of claimed doses for all tested DPIs. The mean MF doses delivered at 28.3 L/min were 100% and 94% of the doses delivered at 60 L/min for the 200-microg and 400-microg dose sizes, respectively; the relative standard deviation of doses was < or = 6.1% within this range of inhalation rates. At a flow rate of 60 L/min, the mean delivered doses, compared to claimed doses for inspiration times of 1-3 sec, were 102-104% for the 200-microg dose size and 98.8-102% for the 400-microg dose size. The mean cumulative fraction of dose delivered at 60 L/min for 2 sec which consisted of particles of <6.5 microm in diameter was 39.9% (+/-2.5 SD; n = 9) for the 200-microg dose size and 35.6% (+/-3.4 SD; n = 9) for the 400-microg dose size. All MF-DPI inhalers tested were well within U.S. and European compendial standards and regulatory guidelines for dose uniformity. An appropriate and reproducible fraction of the delivered dose was within the optimal particle size range for therapeutic effectiveness.
Administration, Inhalation↗
Inhibitory effect of Chinese green tea on endothelial cell-induced LDL oxidation.
Green tea has been shown to inhibit Cu(2+)-induced LDL oxidation and suppress lipoxygenase activity. Since LDL oxidation is a characteristic feature of atherogenesis and lipoxygenase is involved in the disease process, the effect of Lung Chen Tea, a non-fermented Chinese green tea, on LDL oxidation induced by human umbilical cord vascular endothelial cell was investigated in the present study. Lung Chen Tea was extracted with methanol and the dried powder was redissolved in water before extraction with chloroform and then ethyl acetate. Lung Chen Tea, chloroform and ethyl acetate fractions dose-dependently reduced LDL oxidation and decreased its relative electrophoretic mobility (P<0.001) when compared to the oxidized LDL. The lipid peroxidation products, thiobarbituric acid reactive substances, and cellular cholesterol were also significantly lowered by 5 and 10 microg/ml Lung Chen Tea (P<0.001) in a dose-dependent manner. The remaining aqueous layer, which was devoid of catechins after chloroform and ethyl acetate extractions, did not prevent LDL oxidation. The results of this study demonstrated that Lung Chen Tea and catechin-rich fractions significantly prevented endothelial cell induced LDL oxidation. The consumption of Lung Chen Tea may therefore lower the risk of coronary heart diseases.
Cells, Cultured↗
Chinese green tea lowers cholesterol level through an increase in fecal lipid excretion.
Lung Chen Tea, a Chinese green tea, has been found to lower serum and liver cholesterol. In this study, its dose response and mechanisms of action on cholesterol lowering in diet-induced hypercholesterolemic Sprague-Dawley rats were investigated. The activities of three major lipid metabolizing enzymes, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-Co A) reductase, cholesterol 7alpha-hydroxylase and fatty acid synthase (FAS), as well as fecal excretion of bile acids and cholesterol were examined. Lung Chen Tea administration for eight weeks significantly lowered the serum cholesterol in the 2% and 4% groups. The activities of the three enzymes were not affected by Lung Chen Tea, but the fecal bile acids and cholesterol excretions were significantly increased. These results demonstrated that Lung Chen Tea lowered plasma cholesterol by increasing fecal bile acids and cholesterol excretion. Further investigation is required to evaluate the exact mechanisms of action of Lung Chen Tea.
Animals↗
Thyrotropin regulates c-Jun N-terminal kinase (JNK) activity through two distinct signal pathways in human thyroid cells.
c-Jun N-terminal kinases (JNK) participate in cellular responses to mitogenic stimuli and environmental stresses. We investigated whether and how TSH, which promotes the proliferation and differentiation of thyroid cells, regulates JNK activity in primary cultured human thyroid cells. TSH stimulated JNK activity in cytosolic fractions of thyroid cells measured by in vitro kinase assay. A low concentration of TSH (10(-11) M) stimulated JNK activity but at a higher dose (10(-8)-10(-7) M), TSH suppressed JNK activity without any change of JNK protein level. Activation of JNK by TSH was also observed in CHO cells stably transfected with TSH receptor complementary DNA (cDNA), suggesting a ligand-receptor specific interaction. TSH stimulated JNK activity through a pertussis toxin-sensitive pathway. We next elucidated the signal transduction pathways in TSH-induced JNK activation by examining the involvement of four distinct intracellular signal molecules; protein kinase C (PKC), cAMP, Ca2+, and PI3-kinase. The stimulation of JNK by TSH was blocked by two PKC inhibitors and suppressed by 8-bromo-cAMP or forskolin. These findings demonstrate that TSH regulates JNK activity biphasically in human thyroid cells through an interaction between Gi-PKC and cAMP-PKA pathways.
8-Bromo Cyclic Adenosine Monophosphate↗
Improved fluorescence and dual color detection with enhanced blue and green variants of the green fluorescent protein.
The green fluorescent protein (GFP) from the jellyfish Aequorea victoria is a versatile reporter protein for monitoring gene expression and protein localization in a variety of systems. Applications using GFP reporters have expanded greatly due to the availability of mutants with altered spectral properties, including several blue emission variants, all of which contain the single point mutation Tyr-66 to His in the chromophore region of the protein. However, previously described "BFP" reporters have limited utility, primarily due to relatively dim fluorescence and low expression levels attained in higher eukaryotes with such variants. To improve upon these qualities, we have combined a blue emission mutant of GFP containing four point mutations (Phe-64 to Leu, Ser-65 to Thr, Tyr-66 to His, and Tyr-145 to Phe) with a synthetic gene sequence containing codons preferentially found in highly expressed human proteins. These mutations were chosen to optimize expression of properly folded fluorescent protein in mammalian cells cultured at 37 degreesC and to maximize signal intensity. The combination of improved fluorescence and higher expression levels yield an enhanced blue fluorescent protein that provides greater sensitivity and is suitable for dual color detection with green-emitting fluorophores.
Fluorescence↗
Ionizing radiation activates c-Jun NH2-terminal kinase (JNK/SAPK) via a PKC-dependent pathway in human thyroid cells.
Thyroid gland is known to be higher sensitive to carcinogenic effects of external ionizing radiation (IR) than other tissues. To clarify the cell-specific response following irradiation, activations of c-Jun NH2-terminal kinases (JNKs), which is one of mitogen-activated protein kinases (MAPKs) family members, and extracellular signal-regulated kinase (ERK) were examined in primary cultured human thyroid cells in comparison with human diploid fibroblast cells, WI-38. Although UV exposure strikingly induced JNK activity in both cells, the dose-response increase following IR exposure was observed in thyroid cells with the maximal JNK activity (3.5 fold induction) obtained at 10 Gy exposure, but no increase in WI-38 cells. The JNK activity was reached a maximum of 2.2 fold induction at 30 min after 5 Gy exposure and then sustained for at least 12 hr. On the other hand, ERK activity was not stimulated in thyroid cells following irradiation. The effects of 12-O-tetradecanoylphorbol beta-acetate (TPA) mimicked those of radiation on JNK cascade and 1-(5-isoquinolinesulphonyl)-2,5-dimethylpiperazine 2HCl (H7) and pretreatment with TPA blocked JNK activation following irradiation. Our results demonstrate that IR stimulates JNK activity in cultured human thyroid cells but not in fibroblasts indicating distinct activation and regulation mechanisms of JNK cascade. The JNK activation following IR exposure is mediated at least partially through a PKC-dependent pathway.
Calcium-Calmodulin-Dependent Protein Kinases↗
Therapeutic usefulness of wild-type p53 gene introduction in a p53-null anaplastic thyroid carcinoma cell line.
Anaplastic thyroid carcinomas very often harbor the mutations in the tumor suppressor gene p53. We have previously shown that wild-type (wt) p53 gene introduction led to cell growth arrest, but not apoptosis, in p53-null anaplastic thyroid carcinoma cells. The present studies were designed to evaluate other therapeutic effects of wt-p53 gene introduction on p53-null thyroid carcinoma cells, as chemo- and radiosensitization and inhibition of angiogenesis have also been described recently as additional therapeutic advantages of wt-p53 gene introduction in tumor cells with p53 mutations. A p53-null anaplastic thyroid carcinoma cell line, FRO, and a FRO subline stably expressing a temperature-sensitive (ts) mutant of p53 (p53Val138), tsFRO, were used. ts-p53 functions as mutant and wt at nonpermissive (37 C) and permissive (32 C) temperatures, respectively. tsFRO showed a prolonged cell doubling time compared to parental FRO when cultured at 32 C, but the cell growth rate was similar between FRO and tsFRO at 37 C. The cytotoxic and clonogenic assays demonstrated that although the sensitivity to three different anticancer agents (cisplatin, 5-fluorocytosine, and doxorubicin) was unaltered, radiosensitivity was enhanced in tsFRO compared to FRO at 32 C. Unexpectedly, in studies on angiogenesis, expression levels of vascular endothelial growth factor (an angiogenic factor) messenger ribonucleic acid were similar between FRO and tsFRO, and thrombospondin-1 (an antiangiogenic factor) messenger ribonucleic acid and protein levels were about 2.5-fold lower in tsFRO than FRO at 32 C, although any difference could not be detected in their ability to inhibit in vitro angiogenesis with the culture medium conditioned by tsFRO and FRO at 32 C. These results suggest that p53-defective thyroid carcinomas may benefit from the combination of p53 gene therapy and radiotherapy. However, further study will be necessary to clarify the pathological significance of thrombospondin-1 in angiogenesis and thyroid tumor growth.
Antimetabolites, Antineoplastic↗
Hypocholesterolemic effects of Chinese tea.
Chinese teas with different degrees of fermentation were examined for their effect on diet-induced hypercholesterolemia in rats. The teas tested were Chinese Green tea, Jasmine, Iron Buddha, Oolong and Pu erh. Hypercholesterolemia was induced by feeding rats with a cholesterol-enriched diet for 1 week. They were then treated with different tea extracts together with a cholesterol-enriched diet for another 8 weeks. Chinese Green tea and Jasmine tea, both with a minimum degree of fermentation, were found to have significant serum and liver cholesterol lowering effects. They also reduced the increase in liver weight due to lipid deposition. All tea treatments lowered the atherogenic index and increased the HDL-total cholesterol ratio, while HDL-cholesterol and triglyceride levels were not significantly affected. Analysis of catechin levels in tea extracts showed that the individual catechin component in Chinese Green tea and Jasmine tea were significantly higher than the others. (-)-Epicatechin gallate and (-)-epigallocatechin gallate in the tea extracts may account for their hypocholesterolemic effect.
Animals↗
Quantification of gene expression with a secreted alkaline phosphatase reporter system.
The cDNA encoding secreted alkaline phosphatase (SEAP) is a useful tool for investigating the function of known or putative enhancer/promoter elements. SEAP has the unusual properties of extreme heat stability and resistance to the phosphatase inhibitor L-homoarginine. Therefore, endogenous alkaline phosphatase activity in transfected cells can be minimized by pretreatment of samples at 65 degrees C and incubation with the inhibitor. With the use of the chemiluminescent substrate CSPD, 10(-13) g of enzyme can be detected in culture medium, and the enzyme activity can be detected as early as 24 h after transfection. The chemiluminescence-based SEAP assay is about 10-fold more sensitive than similar assays using firefly luciferase as the reporter enzyme. The SEAP activity can also be assayed with a fluorescent substrate MUP, which provides sensitivity comparable to luciferase. Since the enzyme is secreted to culture medium, the enzyme assay can be performed on small samples of the culture supernatant. Because preparation of cell lysates is not required, assaying for SEAP activity is faster and more convenient than assaying for intracellular reporters. Furthermore, because the transfected cells are not disturbed by the sampling procedure, the same cultures can be repeatedly sampled for time-course studies or used for further investigations.
Alkaline Phosphatase↗
Optimized codon usage and chromophore mutations provide enhanced sensitivity with the green fluorescent protein.
The green fluorescent protein (GFP) from Aequorea victoria is a versatile reporter protein for monitoring gene expression and protein localization in a variety of cells and organisms. Despite many early successes using this reporter, wild type GFP is suboptimal for most applications due to low fluorescence intensity when excited by blue light (488 nm), a significant lag in the development of fluorescence after protein synthesis, complex photoisomerization of the GFP chromophore and poor expression in many higher eukaryotes. To improve upon these qualities, we have combined a mutant of GFP with a significantly larger extinction coefficient for excitation at 488 nm with a re-engineered GFP gene sequence containing codons preferentially found in highly expressed human proteins. The combination of improved fluorescence intensity and higher expression levels yield an enhanced GFP which provides greater sensitivity in most systems.
Animals↗
An acid phosphatase assay for quantifying the growth of adherent and nonadherent cells.
We describe an acid phosphatase assay for determination of cell growth based on quantification of cytosolic acid phosphatase activity. The assay is based on the hydrolysis of the p-nitrophenyl phosphate by intracellular acid phosphatases in viable cells to produce p-nitrophenol. For all cell types examined, absorbance of p-nitrophenol at 405 nm is directly proportional to the cell number in the range of 10(3)-10(5) cells. The assay can quantify as few as 1000 cells per well in 96-well microtiter plates. The acid phosphatase assay was used to count various adherent and nonadherent cells, including human tumors, L6, and HT-2 cells. We also demonstrate the utility of this assay for analysis of growth factor and cytokine bioactivity on mammalian cells in culture. In comparison to [3H]thymidine incorporation, the acid phosphatase assay has similar sensitivity but a wider linear response range. The method also shows higher sensitivity and reproducibility in comparison to cell proliferation assays based on the reduction of tetrazolium salts. Because of the ease of use, sensitivity, and low cost, the acid phosphatase method is especially suited to applications where a large number of samples are assayed.
Acid Phosphatase↗
Dual color microscopic imagery of cells expressing the green fluorescent protein and a red-shifted variant.
The green fluorescent protein (GFP) from the jellyfish, Aequorea victoria, has become a versatile reporter for monitoring gene expression and protein localization in a variety of cells and organisms. GFP emits bright green light (lambda max = 510 nm) when excited with ultraviolet (UV) or blue light (lambda max = 395 nm, minor peak at 470 nm). The chromophore in GFP is intrinsic to the primary structure of the protein, and fluorescence from GFP does not require additional gene products, substrates or other factors. GFP fluorescence is stable, species-independent and can be monitored noninvasively using the techniques of fluorescence microscopy and flow cytometry [Chalfie et al., Science 263 (1994) 802-805; Stearns, Curr. Biol. 5 (1995) 262-264]. The protein appears to undergo an autocatalytic reaction to create the fluorophore [Heim et al., Proc. Natl. Acad. Sci. USA 91 (1994) 12501-12504] in a process involving cyclization of a Tyr66 aa residue. Recently [Delagrave et al., Bio/Technology 13 (1995) 151-154], a combinatorial mutagenic strategy was targeted at aa 64 through 69, which spans the chromophore of A. victoria GFP, yielding a number of different mutants with red-shifted fluorescence excitation spectra. One of these, RSGFP4, retains the characteristic green emission spectra (lambda max = 505 nm), but has a single excitation peak (lambda max = 490 nm). The fluorescence properties of RSGFP4 are similar to those of another naturally occurring GFP from the sea pansy, Renilla reniformis [Ward and Cormier, Photobiochem. Photobiol. 27 (1978) 389-396]. In the present study, we demonstrate by fluorescence microscopy that selective excitation of A. victoria GFP and RSGFP4 allows for spectral separation of each fluorescent signal, and provides the means to image these signals independently in a mixed population of bacteria or mammalian cells.
Amino Acid Sequence↗
Identification and characterization of human tissue inhibitor of metalloproteinase-3 and detection of three additional metalloproteinase inhibitor activities in extracellular matrix.
We have identified and characterized a novel human tissue inhibitor of metalloproteinase (TIMP). It is found exclusively in the extracellular matrix of a large number of cultured human cells, including: primary embryonal kidney (293), neuroblastoma (SK-N-SH), normal whole embryo (FHs 173We), cervical carcinoma (HeLa S3), colon adenocarcinoma (Caco-2), ileocecal adenocarcinoma (HCT-8), fibrosarcomas (SW 684 and Hs 913T) and normal gingival fibroblasts (GF11 and 1292). It was not detected in the conditioned media from any of these cell lines. Its apparent molecular mass of 24-25 kDa, as determined by its migration on protease-substrate gels, is intermediate between TIMP-1 (28.5 kDa) and TIMP-2 (21 kDa). Like the latter two proteins, human TIMP-3 contains intrachain disulfide bonds and displays altered electrophoretic mobility in the presence of beta-mercaptoethanol. The N-terminal, amino acid sequence of the protein is identical to that of chicken TIMP-3 (ChIMP-3), and its amino acid composition is similar. The protein is not N-glycosylated, as determined by treatment with N-glycosidase-F. Finally, it is recognized by antisera raised against pure ChIMP-3 but not by anti-human TIMP-1 or anti-human TIMP-2 antibodies. Based on these properties, we propose that this protein is TIMP-3 and is the human counterpart of ChIMP-3 (Pavloff et al., J. Biol. Chem. 267: 17321-17326, 1992). Two additional inhibitors detected in the matrix of human cell lines, designated inhibitor of metalloproteinase (IMP)-a and IMP-b, migrate with apparent masses of 29 kDa and 30 kDa. Both are N-glycosylated. A fourth inhibitor activity, which is smaller in mass than TIMP-3 and is also pecifically located in the matrix, is detectable in some cell lines.
Adenocarcinoma↗
Fast hybridization solution for the detection of immobilized nucleic acids.
We have developed a fast hybridization solution, termed ExpressHyb, for the rapid and sensitive detection of nucleic acids immobilized on membrane supports. This solution reduces typical hybridization times of 12-24 h to as little as 1 h while simultaneously increasing the sensitivity of detection in many applications. Using ExpressHyb, human beta-actin mRNA was detected on a human multiple tissue Northern (MTN) blot following a 30-min hybridization, with optimal detection occurring with a 1-h hybridization interval. The moderately abundant human glyceraldehyde-3-phosphate dehydrogenase (G3PDH) mRNA was detected using similar hybridization conditions and yielded improved signal-to-background characteristics relative to overnight hybridizations in conventional solutions. ExpressHyb can be used with either 32P- or digoxigenin-labeled probes and works effectively with both cDNA and oligonucleotide probes. For non-isotopic detection in particular, ExpressHyb reduces the nonspecific background commonly encountered with this technique. In cDNA library screening, ExpressHyb was found to both reduce the time required for effective hybridizations and to increase the number of positive colonies obtained relative to conventional overnight procedures. Taken together, these results illustrate the broad capability of ExpressHyb Hybridization Solution to improve nucleic acid detection in a variety of important techniques.
Actins↗