Biomedical subjects
Publications and source records attributed to G Li.
The increasing-effect components for molluscicides isolated from the dry nut of Areca catech L. were studied. The results showed that arecoline was the most effective and it could decrease remarkably the amount of drugs i.e. saponium of Phytolacca acinosa, SPA, and sodium pentachloro phenate, NaPCP, when used together.
The identification characteristics of pig's hoofnail on properties and tissue slice was initially probed from the viewpoint of identification in this paper in order to make basis for the systematic research on replacing Squama manitis.
A new instrument for observing blood cell state and the process of variation on hemorrheology has been developed. There are three ways of shear rate: setting by hand, automatically setting and simulating pulsative state. It can provide different variable flow fields. The shear rate can be set in the range from 0.1 to 1000 s-1. It needs only a little blood. It can be easyly and rapidely operated. it has clear images. The hemorrheology state of blood cells can be directly perceived through thd instrument by eyes. The display and measurement and record of blood cell's hemorrheology state can be finished in real time dynamically and simultaneously.
Surface enhanced Raman scattering of thiourea adsorbed on the plated silver surface in an acidic solution has been studied. The results show that the thiourea molecules are inclined to adsorbed on the silver surface via sulphur. When the concentration of HCl in the solution is increased, the plane of the thiourea molecule deviates more from the normal line of the silver surface. The experimental results also suggest that the rather strong chemical enhanced mechanism would exist in this system.
The FTIR spectra of sulfonated polystyrene and Zn and La ionomers change with sulfonation degree and the kind of metal ion. With increasing the sulfonation degree, the stretching vibrational strength of -SO3H and -SO3 increases. Because of the interaction of polar group, the FTIR spectra around 1200 cm(-1) or so split. On the other hand, the degree of sulfonation influences somewhat on the intensity and position of fluorescence spectra of sulfonation polystyrene and its ionomers.
In this paper preparation of standard samples of superhigh-P cast iron has been studied and P in the samples has been determined by EDXRF and powder compacting. In the process the procedure of powder compacting and the software of a multifunctional Lucas-Tooth intenstity correction have been developed. The method is rapid and simple. Analytical results were satisfactory.
Ultraviolet-visible (UV-Vis), infrared transmission reflection absorption (RA) and ATR spectra were used to study the mono-and multi-layer Langmuir-Blodgett (LB) films of C12H25ONaph (1,5)OH at various temperatures to investigate dependencies of the aggregation and phase transitions on the number of monolayers. The UV-vis spectra of the LB films revealed that C12H25ONaph (1,5)OH forms aggregates in the LB film. From the temperature dependence of UV-vis absorption spectra, it is clear that the aggregate was gradually converted to monomer with the temperature increased. A comparison of the infrared transmission and ATR spectra reveals that the hydrocarbon chains were tilted considerably in the LB film.
A sideband on the low energy side of the local-vibrational-mode main absorption band of carbon acceptor in GaAs was observed. The difference between the peak frequency of the main absorption band and that of the sideband is 3.5 cm(-1). The integrated absorption of the sideband varies with temperature and has an effect on the temperature dependence of the main absorption band. It is likely that the sideband originates from the anharmonicity of the local vibrational mode itself.
The Fas system has been identified as a key regulator of testicular germ cell apoptosis. The goal of these experiments was to explore the expression of Fas system-related genes in the testis during development and after toxicant exposure. Both Fas ligand (FasL) and Fas receptor (Fas) were expressed postnatally in rat testis with peak expression associated with the high levels of germ cell apoptosis found during the first wave of spermatogenesis. The testicular expression of RIP and FAP-1, components of the Fas activating complex, increased after exposure to mono-(2-ethylhexyl)phthalate (MEHP), a Sertoli cell toxicant which induces massive germ cell death. Finally, the expression of additional apoptosis-inducing genes, including tumor necrosis factor receptor (TNFR), FADD, TRAIL, and DR5, was detected in mammalian testis. These results provide additional support for the following concepts: (1) Sertoli-germ cell interactions are important in the control of germ cell apoptosis; and (2) the Fas system and similar paracrine systems are important modulators of testicular homeostasis.
The SH2- and SH3-containing adaptor molecules serve to recruit cytosolic signal-transducing molecules to the activated receptor tyrosine kinases. In this study, we report the molecular cloning of a novel adaptor-like protein, Grap-2 (Grb-2 related adaptor protein 2), using the multisubstrate docking protein Gab-1 as bait in the yeast two-hybrid system. Sequence analysis revealed that Grap-2 contains a SH3-SH2-SH3 structure that has a high degree of sequence homology to those of the Grb-2 and Grap adaptor molecules. However, unlike in Grap and Grb-2, the SH2 and the C-terminal SH3 domains of Grap-2 are separated by a 120-amino-acid glutamine-rich sequence that shows no apparent homology to any known molecule or structural motif. The C-terminal SH3 domain of Grap-2 alone is sufficient to bind to Gab-1. Furthermore, Northern blot analysis demonstrated that Grap-2 has two major transcripts of 1.4 and 4.0 kb that can only be detected in tissues rich in leukocytes and in two leukemia cell lines. This highly restricted pattern of expression suggests that Grap-2 may participate in leukocyte-specific protein tyrosine kinase signaling.
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OBJECTIVE: To search differentially expressed sequences correlated with pathogenesis of human nasopharyngeal carcinoma (NPC), including the candidates of tumor suppressor genes. METHODS: cDNA representational difference analysis (RDA) was performed to isolate differentially expressed sequences between cDNA from normal human primary cultures of nasopharyngeal epithelial cells and cDNA from NPC cell line HNE1. The sources of differentially expressed products were proved by Southern blot and Northern blot. The fragments were cloned with pGEM-T easy kit and sequenced by the chain termination reaction. RESULTS: Four differentially expressed cDNA fragments were isolated in the fourth subtractive hybridization using cDNA from normal human primary cultures of nasopharyngeal epithelial cells as tester amplicon and cDNA from NPC cell line HNE1 as driver amplicon by cDNA RDA. These differential cDNA fragments revealed that they really came from the tester amplicon and were not expressed or down-regulated in the NPC HNE1 cells. Of these obtained clones, some are the fragments of the human known genes including house-keeping genes, the others are novel genes. CONCLUSION: NPC involves alteration of multiple genes. Some of known genes matched with the differentially expressed sequences have an effective suppressive ability on the carcinoma.
We report an RNA targeting strategy, which selectively degrades bcr/abl mRNA in chronic myelogenous leukemia (CML) cells. A 2', 5'-tetraadenylate activator (2-5A) of RNase L was chemically linked to oligonucleotide antisense directed against either the fusion site or against the translation start sequence in bcr/abl mRNA. Selective degradation of the targeted RNA sequences was demonstrated in assays with purified RNase L and decreases of p210(bcr/abl) kinase activity levels were obtained in the CML cell line, K562. Furthermore, the 2-5A-antisense chimeras suppressed growth of K562, while having substantially reduced effects on the promyelocytic leukemia cell line, HL60. Findings were extended to primary CML cells isolated from bone marrow of patients. The 2-5A-antisense treatments both suppressed proliferation of the leukemia cells and selectively depleted levels of bcr/abl mRNA without affecting levels of beta-actin mRNA, determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The specificity of this approach was further shown with control oligonucleotides, such as chimeras containing an inactive dimeric form of 2-5A, antisense lacking 2-5A, or chimeras with altered sequences including several mismatched nucleotides. The control oligonucleotides had either reduced or no effect on CML cell growth and bcr/abl mRNA levels. These findings show that CML cell growth can be selectively suppressed by targeting bcr/abl mRNA with 2-5A-antisense for decay by RNase L and suggest that these compounds should be further explored for their potential as ex vivo purging agents of autologous hematopoietic stem cell transplants from CML patients.
Our research goal is to better understand the mechanisms controlling the initiation and progression of thyroid diseases. One such disease, papillary thyroid carcinoma (PTC), is the leading endocrine malignancy in the United States. Recently, a family of related fusion proteins, RET/PTC1-5, has been implicated in the early stages of PTC. Although all five members of this family have the c-RET proto-oncogene kinase domain in their COOH terminus, little is known about how these genes alter follicular cell biology. Consequently, to answer questions related to the mechanism of the RET/PTC fusion protein action, we have devised a molecular genetic strategy to study PTC using a mouse model of thyroid disease. A new member of this fusion oncogene family, RET/PTC3, which has been implicated in more cases of solid tumor carcinoma (79%) than PTC1 or PTC2 and predominates (80%) in radiation-induced thyroid cancer of children, was investigated in our study. We have generated transgenic mice expressing human RET/PTC3 exclusively in the thyroid. These mice develop thyroid hyperplasia, solid tumor variants of papillary carcinoma and metastatic cancer. This new transgenic line will be useful in deciphering the molecular and biological mechanisms that cause PTC and histological variations in humans.
BACKGROUND: Idiopathic hypertrophic obstructive cardiomyopathy (HOCM) is characterized by regional myocardial hypertrophy. In our previous study, we demonstrated that mRNA levels for insulin-like growth factor-I (IGF-I) and transforming growth factor-beta 1 (TGF-beta 1) were elevated in HOCM tissue. In this study, we investigated IGF-I and TGF-beta 1 protein levels and their respective receptor levels and localization. METHODS AND RESULTS: Myocardial growth factor protein levels were quantified with the use of chemiluminescent slot blot analysis with monoclonal antibodies against IGF-I and TGF-beta. The growth factor receptor binding sites were evaluated with 125I-labeled IGF-I and TGF-beta 1. The receptors were localized with immunohistochemistry. Data were expressed as mean +/- SEM. IGF-I and TGF-beta protein levels in HOCM myocardium (351.8 +/- 46.5 and 17.4 +/- 2.0 ng/g tissue, respectively; n = 6) were significantly higher (P < 0.01 for all groups) than in non-HOCM myocardium obtained from patients with aortic stenosis (AS, 182.1 +/- 22.7 and 8.0 +/- 1.2 ng/g tissue, respectively; n = 5), stable angina (SA, 117.4 +/- 20.9 and 7.5 +/- 2.7 ng/g tissue, respectively; n = 5), and transplanted hearts (TM, 166.3 +/- 30.1 and 6.4 +/- 1.2 ng/g tissue, respectively; n = 5). Maximal and high-affinity binding sites for IGF-I receptor in the HOCM were greater (P < 0.01 and P < 0.05) than the levels in AS, SA, and TM. The maximal receptor binding sites for TGF-beta 1 in HOCM were greater (P < 0.05) than those for SA and TM. Immunohistochemistry demonstrated that IGF-I and TGF-beta 1 receptors were located on the cardiomyocytes and TGF-beta 1 receptors were located on the fibroblasts. CONCLUSIONS: Increased IGF-I and TGF-beta 1 gene expression previously observed in HOCM myocardium results in elevated protein levels. IGF-I and TGF-beta 1 signals may be further amplified by increased receptor numbers on cardiomyocytes and fibroblasts. The data suggest a possible autocrine mechanism of IGF-I-stimulated cardiomyocyte hypertrophy and a paracrine mechanism of TGF-beta 1-stimulated extracellular matrix overproduction in HOCM.
Paclitaxel (Taxol) is a novel anti-cancer drug that has shown efficacy toward several malignant tumors, particularly ovarian tumors. We reported previously that paclitaxel can induce interleukin (IL)-8 promoter activation in subgroups of ovarian cancer through the activation of both AP-1 and nuclear factor kappaB. Further analysis of paclitaxel analogs indicates that the degree of IL-8 induction by analysis correlates with the extent of cell death; however, IL-8 itself is not the cause of cell death. This suggests that pathways that lead to IL-8 and cell death may overlap, although IL-8 per se does not kill tumor cells. To decipher the upstream signals for paclitaxel-induced transcriptional activation and cell death, we studied the involvement of protein kinases that lead to the activation of AP-1, specifically the c-Jun NH2-terminal kinase (JNK1), p38, and the extracellular signal-regulated kinase 1 (ERK1). The role of IkappaB in paclitaxel-induced cell death was also analyzed. Paclitaxel activated JNK, and to a lesser degree p38, but not ERK1. Paclitaxel-induced IL-8 promoter activation was inhibited by dominant-inhibitory mutants of JNK, p38, and the super-repressor form of IkappaBalpha, but not by dominant-inhibitory forms of ERK1. Dominant-inhibitory mutants of JNK1 also greatly reduced paclitaxel-induced cell death, and the kinetics of JNK induction was closely followed by DNA fragmentation. These results indicate (i) that paclitaxel activates the JNK signaling pathway and (ii) that JNK activation is a common point of paclitaxel-induced gene induction and cell death.
A biosensor based on an H+ ion sensitive field effect transistor (H+(-)ISFET) and penicillin G acylase has been developed. The response time of the sensor to different concentrations of penicillin G was 30 s. In a 20 mM phosphate buffer at pH 7.0, the linear range of the calibration curve was from 0.5 to 8 mM. The coefficients of variation for three samples with 20 repeated measurements were below 5%. Stability of the sensor could reach about 6 months and more than 1000 runs were performed without a significant decrease of the output value. The sensor was tested for measurement of the penicillin G content in penicillin fermentation both. Forty samples with low and high concentrations of penicillin G were chosen for the correlation test. The values assayed by the sensor method were compared with the values assayed by HPLC method, the correlation coefficient (r) was 0.9944 and the regression equation was y = 1.034X - 2083.7, respectively. The different measuring methods are discussed in the text.
OBJECTIVE: To establish partial gene expression map of 7q32 in nasopharyngeal carcinoma (NPC) cell line, tissues and primary culture normal nasopharyngeal epithelial cells. METHODS: We detected the expression of 20 ESTs at 7q32 in NPC cell line HNE1,13 NPC biopsies and primary culture normal nasopharyngeal epithelial cells using differential RT PCR and Northern hybridization. RESULTS: 8 ESTs (AA188181, AA13079,N27556, AA031919, N22721, H20825, T91284, AA001936) expressed equally in both of HNE1 and primary culture normal nasopharyngeal epithelial cells; 7 ESTs (T64215, AA025822, R60014,R80002,H06688, R60192,R95096) expressed in neither of them; 3 ESTs (H19830,W72688,AA130630) overexpressed in HNE1 ; and 2 ESTs (AA070437, H90882) overexpressed in primary culture normal nasopharyngeal epithelial cells. W72688 and H19830 each overexpressed in 77%(10/13) of NPC biopsies; AA070437 down-expressed in 30.7% of NPC biopsies. CONCLUSION: Partial gene expression map of 7q32 in nasopharyngeal carcinoma cell line ,tissues and primary culture normal nasopharyngeal epithelial cells has been established. The up-regulation of W72688, H19830 and down-regulation of AA070437 may be related to the occurrence of NPC.