Biomedical subjects

J Pan

Publications and source records attributed to J Pan.

At least 73 records · Page 4Linked to original sources

PubMed2001

[The experiment of pegylated liposomal doxorubicin to therapy tongue cancer and metastases lymph nodes].

OBJECTIVE: To investigate the effects of pegylated liposmal doxorubicin (PLD) in treating animal model of tongue cancer. METHODS: The tongue cancer model was established in 70 goldn hamsters, and PLD was injected. The free doxorubicin and its concentration in circulating blood and lymph nodes, the weight of animals, volume of tumor, were defected. RESULTS: Tumor inhibition effect of the PLD group was higher than controls. CONCLUSIONS: PLD can be regarded as a valuable drug system to treat oral cancer.

Animals↗

PubMed2001

[Combining transvaginal sonography and endometrial cytology in the diagnosis of endometrial disorders in postmenopausal women].

OBJECTIVE: To evaluate the combined use of transvaginal sonography and endometrial cytology for the diagnosis of endometrial disorders in postmenopausal women. METHODS: One hundred forty-three patients with postmenopausal uterine bleeding were studied prospectively. Transvaginal sonography was used to measure the endometrial thickness (double layers), followed by use of the ori endometrial sampler. The results were compared to the histopathologic diagnosis of specimens obtained by dilatation and curettage. RESULTS: When the cutoff point of endometrial thickness was set at 5 mm to detect endometrial malignancy and premalignancy, transvaginal sonography showed a 100.0% sensitivity and 56.9% false positive rate. Endometrial cytology showed a 96.3% specificity but it had a 2.5% false negative rate. The combined use of transvaginal sonography and endometrial cytology can decrease false positive rate of transvaginal sonography from 56.9% to 43.2% (P < 0.01). CONCLUSION: The combined use of transvaginal sonography and endometrial cytology is a good method to screen endometrial malignancy and premalignancy.

Adult↗

PubMed2001

[Corrosion of biomedical metallic materials].

The recent results of the studies on corrosion of biomedical metallic materials are reviewed. The investigations on in vitro and in vivo corrosion and the correspondent local tissue responses, remote and systematic effects are discussed in order to explore the corrosion mechanism and to estimate the biocompatibility. The further research and development of bio-medical metallic materials are addressed.

Animals↗

PubMed2001

Temperature fields during the development of autoignition in a rapid compression machine.

Temperature and concentration fields have been investigated in the cylindrical combustion chamber of a rapid compression machine (RCM) by schlieren photography, chemiluminescent imaging and planar laser induced fluorescence of acetone and of formaldehyde in a 2-dimensional sheet across the diameter. The timescale of particular interest was up to 10 ms after the piston has stopped. Experiments were performed in non-reactive and reactive conditions. Acetone was seeded in non-reactive mixtures. Combustion was studied first in a system containing di-tert-butyl peroxide vapour in the presence of oxygen. The decomposition of di-tert-butyl peroxide generates methyl radicals, which are then oxidised if oxygen is present. The overall reaction is exothermic and is characteristic of a conventional thermal ignition. In addition, chemiluminescence, resulting from CH2O*, accompanies the oxidation process. The combustion of n-pentane was then investigated at compressed gas temperatures that spanned the range in which there is a negative temperature dependence of the overall reaction rate, typically 750-850 K. The response to thermal feedback in this more complex thermokinetic system can be the opposite of the "thermal runaway" that accompanies di-tert-butyl peroxide combustion. The purpose of making comparisons between these two types of systems was to show how the temperature field generated in the RCM is modified in different ways by the interaction with the chemistry and to discuss the implications of this for the spatial development of spontaneous ignition. As the piston of the RCM moves it shears gas off the walls of the chamber. This probably creates a roll-up vortex, but more importantly it also collects gas from the walls and moves it across the cylinder head pushing it forward into a plug at the centre. Thus, soon after the end of compression there is an adiabatically heated gas which extends virtually to the wall, but this incorporates a plug of colder gas at its core. Diffusive transport will occur, but the timescale is relatively slow, and the effect hardly shows until at least 10 ms post-compression. The consequence of "thermal runaway" on a timescale that is compatible with the development of this temperature field is that the reaction rate in the adiabatically compressed toroidal region accelerates faster than in the core, and goes to completion first. A somewhat similar pattern emerges during n-pentane combustion when the initial condition is set at the lower end of the negative temperature dependent range. By contrast, at adiabatically compressed gas temperatures close to the upper end of the negative temperature dependent region, the reaction rate in the cooler core develops faster than that in the surrounding zone, and the temperature difference is rapidly smoothed out. This does not lead to spatial homogeneity in all respects, however, because different rates and extents of reaction generate different concentrations of intermediates. This stratification has implications for the eventual spatial evolution of spontaneous ignition.

Journal Article↗

PubMed2001

[A retrospective clinical study of 6539 cases of malignant oral-maxillofacial tumors].

OBJECTIVE: The aim of this study is to obtain the general information of post-operation malignant oral-maxillofacial tumor patients in forty-seven years. METHODS: A total of 6539 patients with malignant oral-maxillofacial tumors in the hospital of stomatology, west china university of medical sciences, from 1953 to 2000 were retrospected. RESULTS: The average age of patients with malignant oral-maxilloficial tumor is 48.7 years old. The ratio of male to female is 2.31:1. The most common original malignant tumors in this oral-maxillofacial region are malignant oral tumors, malignant maxillary tumors, malignant mandibular tumors, and malignant sialoma successively. As to the original tissues of tumors, there were 5869 cases of epithelial tumors, and made up 89.75% of all the investigated patients. Tumors came from lymphatic and hematopoietic systems and mesoderm were much less those came from epithelia. There were 4177 cases of squamous cell carcinomas and the percentage was 63.88%. CONCLUSION: The incidence rate of malignant tumors in oral-maxillofacial region tends to increase, and the average age of patients also rose. The ratio of male to female decreases gradually. Epithelial tumors, especially squamous cell carcinomas are very common tumors happening in this region.

Adolescent↗

PubMed2000

Automated crystal mounting and data collection for protein crystallography.

To increase the efficiency of diffraction data collection for protein crystallographic studies, an automated system designed to store frozen protein crystals, mount them sequentially, align them to the X-ray beam, collect complete data sets, and return the crystals to storage has been developed. Advances in X-ray data collection technology including more brilliant X-ray sources, improved focusing optics, and faster-readout detectors have reduced diffraction data acquisition times from days to hours at a typical protein crystallography laboratory [1,2]. In addition, the number of high-brilliance synchrotron X-ray beam lines dedicated to macromolecular crystallography has increased significantly, and data collection times at these facilities can be routinely less than an hour per crystal. Because the number of protein crystals that may be collected in a 24 hr period has substantially increased, unattended X-ray data acquisition, including automated crystal mounting and alignment, is a desirable goal for protein crystallography. The ability to complete X-ray data collection more efficiently should impact a number of fields, including the emerging structural genomics field [3], structure-directed drug design, and the newly developed screening by X-ray crystallography [4], as well as small molecule applications.

Crystallization↗

PubMed2000

Characterization of CAF4 and CAF16 reveals a functional connection between the CCR4-NOT complex and a subset of SRB proteins of the RNA polymerase II holoenzyme.

The CCR4-NOT transcriptional regulatory complex affects transcription both positively and negatively and consists of the following two complexes: a core 1 x 10(6) dalton (1 MDa) complex consisting of CCR4, CAF1, and the five NOT proteins and a larger, less defined 1.9-MDa complex. We report here the identification of two new factors that associate with the CCR4-NOT proteins as follows: CAF4, a WD40-containing protein, and CAF16, a putative ABC ATPase. Whereas neither CAF4 nor CAF16 was part of the core CCR4-NOT complex, both CAF16 and CAF4 appeared to be present in the 1.9-MDa complex. CAF4 also displayed physical interactions with multiple CCR4-NOT components and with DBF2, a likely component of the 1.9-MDa complex. In addition, both CAF4 and CAF16 were found to interact in a CCR4-dependent manner with SRB9, a component of the SRB complex that is part of the yeast RNA polymerase II holoenzyme. The three related SRB proteins, SRB9, SRB10, and SRB11, were found to interact with and to coimmunoprecipitate DBF2, CAF4, CCR4, NOT2, and NOT1. Defects in SRB9 and SRB10 also affected processes at the ADH2 locus known to be controlled by components of the CCR4-NOT complex; an srb9 mutation was shown to reduce ADH2 derepression and either an srb9 or srb10 allele suppressed spt10-enhanced expression of ADH2. In addition, srb9 and srb10 alleles increased ADR1(c)-dependent ADH2 expression; not4 and not5 deletions are the only other known defects that elicit this phenotype. These results suggest a close physical and functional association between components of the CCR4-NOT complexes and the SRB9, -10, and -11 components of the holoenzyme.

Adenosine Triphosphatases↗

PubMed2000

Interleukin-6 family of cytokines mediate angiotensin II-induced cardiac hypertrophy in rodent cardiomyocytes.

This study was designed to investigate whether angiotensin II induces the interleukin (IL)-6 family of cytokines in cardiac fibroblasts and, if so, whether these cytokines can augment cardiac hypertrophy. Angiotensin II increased IL-6, leukemia inhibitory factor (LIF) and cardiotrophin-1 mRNA by 6.5-, 10.2-, and 2.0-fold, respectively, but did not affect IL-11, ciliary neurotrophic factor, or oncostatin M in cardiac fibroblasts. Enzyme-linked immunosorbent assay revealed that angiotensin II-stimulated conditioned medium from cardiac fibroblasts contained 9.3 ng/ml IL-6 at 24 h, which was 24-fold higher than the control. It phosphorylated gp130 and STAT3 in cardiomyocytes, which was reduced with RX435 (anti-gp130 blocking antibody). It increased [(3)H]phenylalanine uptake and cell area by 44% and 86% in cardiomyocytes compared with mock medium. RX435 suppressed these increases by 26% and 38%, while TAK044 (endothelin-A/B-R blocker) suppressed them by 52% and 52%, respectively. Antisense oligonucleotides against LIF and cardiotrophin-1 blocked their up-regulation, and attenuated the conditioned medium-induced increase in [(3)H]phenylalanine uptake by 21% and 13%, respectively. The combination of antisense oligonucleotides to LIF and cardiotrophin-1 decreased their uptake by 33%. These results indicated that angiotensin II induced IL-6, LIF, and cardiotrophin-1 in cardiac fibroblasts, and that these cytokines, particularly LIF and cardiotrophin-1, activated gp130-linked signaling and contributed to angiotensin II-induced cardiomyocyte hypertrophy.

Angiotensin II↗

PubMed2000

A novel chemokine ligand for CCR10 and CCR3 expressed by epithelial cells in mucosal tissues.

Mucosae-associated epithelial chemokine (MEC) is a novel chemokine whose mRNA is most abundant in salivary gland, with strong expression in other mucosal sites, including colon, trachea, and mammary gland. MEC is constitutively expressed by epithelial cells; MEC mRNA is detected in cultured bronchial and mammary gland epithelial cell lines and in epithelia isolated from salivary gland and colon using laser capture microdissection, but not in the endothelial, hemolymphoid, or fibroblastic cell lines tested. Although MEC is poorly expressed in skin, its closest homologue is the keratinocyte-expressed cutaneous T cell-attracting chemokine (CTACK; CCL27), and MEC supports chemotaxis of transfected lymphoid cells expressing CCR10, a known CTACK receptor. In contrast to CTACK, however, MEC also supports migration through CCR3. Consistent with this, MEC attracts eosinophils in addition to memory lymphocyte subsets. These results suggest an important role for MEC in the physiology of extracutaneous epithelial tissues, including diverse mucosal organs.

Amino Acid Sequence↗

PubMed2000

Lymphocyte CC chemokine receptor 9 and epithelial thymus-expressed chemokine (TECK) expression distinguish the small intestinal immune compartment: Epithelial expression of tissue-specific chemokines as an organizing principle in regional immunity.

The immune system has evolved specialized cellular and molecular mechanisms for targeting and regulating immune responses at epithelial surfaces. Here we show that small intestinal intraepithelial lymphocytes and lamina propria lymphocytes migrate to thymus-expressed chemokine (TECK). This attraction is mediated by CC chemokine receptor (CCR)9, a chemoattractant receptor expressed at high levels by essentially all CD4(+) and CD8(+) T lymphocytes in the small intestine. Only a small subset of lymphocytes in the colon are CCR9(+), and lymphocytes from other tissues including tonsils, lung, inflamed liver, normal or inflamed skin, inflamed synovium and synovial fluid, breast milk, and seminal fluid are universally CCR9(-). TECK expression is also restricted to the small intestine: immunohistochemistry reveals that intense anti-TECK reactivity characterizes crypt epithelium in the jejunum and ileum, but not in other epithelia of the digestive tract (including stomach and colon), skin, lung, or salivary gland. These results imply a restricted role for lymphocyte CCR9 and its ligand TECK in the small intestine, and provide the first evidence for distinctive mechanisms of lymphocyte recruitment that may permit functional specialization of immune responses in different segments of the gastrointestinal tract. Selective expression of chemokines by differentiated epithelium may represent an important mechanism for targeting and specialization of immune responses.

Animals↗

PubMed2000

Regulated targeting of a protein kinase into an intact flagellum. An aurora/Ipl1p-like protein kinase translocates from the cell body into the flagella during gamete activation in chlamydomonas.

In the green alga Chlamydomonas reinhardtii flagellar adhesion between gametes of opposite mating types leads to rapid cellular changes, events collectively termed gamete activation, that prepare the gametes for cell-cell fusion. As is true for gametes of most organisms, the cellular and molecular mechanisms that underlie gamete activation are poorly understood. Here we report on the regulated movement of a newly identified protein kinase, Chlamydomonas aurora/Ipl1p-like protein kinase (CALK), from the cell body to the flagella during gamete activation. CALK encodes a protein of 769 amino acids and is the newest member of the aurora/Ipl1p protein kinase family. Immunoblotting with an anti-CALK antibody showed that CALK was present as a 78/80-kDa doublet in vegetative cells and unactivated gametes of both mating types and was localized primarily in cell bodies. In cells undergoing fertilization, the 78-kDa CALK was rapidly targeted to the flagella, and within 5 min after mixing gametes of opposite mating types, the level of CALK in the flagella began to approach levels normally found in the cell body. Protein synthesis was not required for targeting, indicating that the translocated CALK and the cellular molecules required for its movement are present in unactivated gametes. CALK was also translocated to the flagella during flagellar adhesion of nonfusing mutant gametes, demonstrating that cell fusion was not required for movement. Finally, the requirement for flagellar adhesion could be bypassed; incubation of cells of a single mating type in dibutyryl cAMP led to CALK translocation to flagella in gametes but not vegetative cells. These experiments document a new event in gamete activation in Chlamydomonas and reveal the existence of a mechanism for regulated translocation of molecules into an intact flagellum.

Amino Acid Sequence↗

PubMed2000

Examination of N-hydroxylation as a prerequisite mechanism of nitric oxide synthase inactivation.

L-N5-(1-Hydroxyiminoethyl)-ornithine (L-NHIO) and L-N6-(1-hydroxyiminoethyl)-lysine (L-NHIL) were synthesized and tested as potential intermediates in the mechanism-based inactivation of nitric oxide synthase (NOS) by L-N5-iminoethylornithine (L-NIO) and L-N6-iminoethyllysine (L-NIL). Although these compounds were determined to be competitive inhibitors, mechanism-based inactivation was not observed.

Binding, Competitive↗

PubMed2000

Pw1/Peg3 is a potential cell death mediator and cooperates with Siah1a in p53-mediated apoptosis.

Induction of wild-type p53 in mouse fibroblasts causes cell cycle arrest at the G(1) phase, whereas coexpression of p53 and the protooncogene c-myc induces apoptosis. Although p53 transcriptional activity generally is required for both pathways, the molecular components mediating p53-dependent apoptosis are not well understood. To identify factors that could mediate p53-induced cell death, we used a comparative RNA differential display procedure. We have identified Pw1/Peg3 as a gene product induced during p53/c-myc-mediated apoptosis. Pw1/Peg3 is not induced during p53-mediated G(1) growth arrest nor by c-myc alone. Although it is not clear whether the induction of Pw1/Peg3 depends on p53 activity, we show that Pw1/Peg3 interacts with a p53-inducible gene product Siah1a. We demonstrate that coexpression of Pw1/Peg3 with Siah1a induces apoptosis independently of p53 whereas expression of Pw1/Peg3 or Siah1a separately has no effect on cell death. These data suggest that Siah1a and Pw1/Peg3 cooperate in the p53-mediated cell death pathway. Furthermore, we show that inhibiting Pw1/Peg3 activity blocks p53-induced apoptosis. The observation that Pw1/Peg3 is necessary for the p53 apoptotic response suggests a pivotal role for this gene in determining cell death versus survival.

3T3 Cells↗

PubMed2000

Fast folding of a ribozyme by stabilizing core interactions: evidence for multiple folding pathways in RNA.

Folding of the Tetrahymena ribozyme under physiological conditions in vitro is limited by slow conversion of long-lived intermediates to the active structure. These intermediates arise because the most stable domain of the ribozyme folds 10-50 times more rapidly than the core region containing helix P3. Native gel electrophoresis and time-resolved X-ray-dependent hydroxyl radical cleavage revealed that mutations that weaken peripheral interactions between domains accelerated folding fivefold, while a point mutation that stabilizes P3 enabled 80 % of the mutant RNA to reach the native conformation within 30 seconds at 22 degrees C. The P3 mutation increased the folding rate of the catalytic core as much as 50-fold, so that both domains of the ribozyme were formed at approximately the same rate. The results show that the ribozyme folds rapidly without significantly populating metastable intermediates when native interactions in the ribozyme core are stabilized relative to peripheral structural elements.

Animals↗

PubMed2000

Manumycin enhances the cytotoxic effect of paclitaxel on anaplastic thyroid carcinoma cells.

Despite the current multimodal approach to treatment of anaplastic thyroid cancer (ATC), the prognosis for patients with the disease is poor. New effective therapy for ATC is desperately needed. Thus, we investigated the effects of manumycin (a farnesyl:protein transferase inhibitor), alone and in combination with other drugs frequently used to treat ATC, in six human ATC cell lines: ARO, C643, DRO, Hth-74, KAT-4, and KAT-18. By means of a formazan dye-based spectrophotometric assay of cell viability and light microscopy, manumycin was shown to decrease the number of viable cells in all six of the cell lines though to a lesser degree in DRO and C643 cells than in ARO, Hth-74, KAT-4, and KAT-18 cells. In combination, manumycin enhanced the effect of paclitaxel in all six of the cell lines. The mechanism of cell death was investigated by measuring caspase-3 activity, immunoblotting with anti-poly-(ADP-ribose)polymerase (PARP) antibody and electrophoresis of DNA. After an 18-h incubation, manumycin plus paclitaxel caused enhanced activation of caspase-3 activity, cleavage of PARP into Mr 89,000 and 28,000 fragments, and internucleosomal fragmentation of DNA (all of which are characteristic of apoptotic cell death). In contrast, neither manumycin alone, paclitaxel alone, doxorubicin alone, nor doxorubicin plus manumycin produced significant specific cleavage of PARP and internucleosomal DNA fragmentation after 18 h of incubation. The in vivo effect and toxicity of combined manumycin and paclitaxel treatments were evaluated in a nude mouse xenograft model using ARO and KAT-4 cells. Drugs were injected i.p. on days 1 and 3 of a 7-day cycle for three cycles. Both manumycin (7.5 mg/kg/dose) and paclitaxel (20 mg/kg/dose) had significant inhibitory effects on tumor growth. Combined manumycin and paclitaxel treatments seemed as effective as manumycin against ARO cells and more effective than either manumycin or paclitaxel alone against KAT-4 cells. No significant morbidity or mortality was caused by the treatments. In conclusion, manumycin can inhibit the growth of ATC both in vitro and in vivo. Manumycin plus paclitaxel has enhanced cytotoxic effects and increased apoptotic cell death in ATC cells in vitro compared with either drug by itself. The combination of manumycin and paclitaxel is also effective in vivo with no significant toxicity observed. The lack of synergy observed in this in vivo experiment may be due to a ceiling effect, and further experimentation is warranted to ascertain the optimal way to combine these two agents for maximal therapeutic effects.

Alkyl and Aryl Transferases↗

PubMed2000

Characterization of progressive changes in ZPC of the vitelline membrane of quail oocyte following oviductal transport.

The inner layer of the vitelline membrane of avian oocyte is equivalent to the zona pellucida of mammalian oocytes or to the vitelline envelope of amphibian oocytes. One of the two major glycoproteins in the inner layer of quail vitelline membrane, formerly called 33-kDa glycoprotein, is homologous to mammalian ZPC, one of the components of zona pellucida. Quail ZPC is found to have different mobilities on SDS-polyacrylamide gel electrophoresis depending on whether it is obtained from the preovulatory follicle or from the laid eggs. In order to characterize the progressive changes in the molecular size of quail ZPC during the oviductal transport, the inner layer isolated from the follicle was incubated in vivo in various regions of the oviduct and subjected to Western blot analysis with anti-quail ZPC antiserum. The quail ZPC of the inner layer incubated in infundibulum reduced its apparent molecular weight, exhibiting the same electrophoretic mobility as that of laid eggs. The similar reduction in molecular weight was observed after the in vitro incubation of the inner layer with the extracts of infundibulum. From the comparison of the N-terminal amino acid sequences, it was found that the first 26 residues of the quail ZPC in follicular oocytes are missing from the ZPC of laid eggs. In addition, lectin blot analysis suggested the modification of oligosaccharide chains during the oviductal transport. These results represent the first description in the avian oviduct of the presence of protease, which is similar to oviductin, a trypsin-like protease involved in the hydrolysis of a major component of the vitelline envelope of amphibian oocytes. Mol. Reprod. Dev. 55:175-181, 2000.

Amino Acid Sequence↗

PubMed2000

Isolation and characterization of myrmexins, six isoforms of venom proteins with anti-inflammatory activity from the tropical ant, Pseudomyrmex triplarinus.

Venom from the tropical ant, Pseudomyrmex triplarinus, has anti-inflammatory properties demonstrated by the carrageenin-induced edema animal mode. A multi-protein complex that inhibits edema was isolated from the venom and was further characterized by high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and amino acid sequencing. Although the complex exhibited a single band in SDS-PAGE electrophoresis, six proteins (isoforms) were resolved and purified to homogeneity and were designated myrmexin I-VI. They have very similar molecular masses between 6998 and 7142 Da. Each myrmexin is a heterodimer consisting of a small subunit (SS1 or SS2 or SS3) disulfide-linked to a larger, quite structurally unrelated subunit (LS1 or LS2). Thus, the myrmexin complex consists of six isoforms of venom proteins: myrmexin I (SS1/LS2), myrmexin II (SS1/LS1), myrmexin III (SS2/LS2), myrmexin IV (SS3/LS2), myrmexin V (SS2/LS1), myrmexin VI (SS3/LS1). Subunit SS1 is highly homologous to SS2 (96% of identity) and SS3 (87% of identity) and LS1 is highly homologous to LS2 (79% of identity). Our study suggests that myrmexins may represent a new class of anti-inflammatory proteins.

Amino Acid Sequence↗

PubMed2000

Broad antiviral activity in tissues of crustaceans.

Innate antiviral substances occur in vertebrates and may function as host defenses. Virus infections are common among invertebrates, but little is known about the ability of invertebrates to control viral infections. Pre-existing antiviral substances may be particularly important, since invertebrates lack the antiviral defense conferred by specific immunity. In our study, we found that tissue extracts of blue crab (Callinectes sapidus), shrimp (Penaeus setiferus), and crayfish (Procambarus clarkii) contained antiviral activities that inhibit a variety of DNA and RNA viruses, i.e. Sindbis virus (SB), vaccinia virus (VAC), vesicular stomatitis virus (VS), mengo virus (MENGO), banzi virus (BANZI) and poliomyelitis (POLIO). The concentration of inhibitory activity was relatively high, ranging from 102 to 216 U/g tissue for Sindbis virus, using the various tissue extracts. The other viruses were somewhat less sensitive to the inhibitor. The main antiviral activity in the inhibitor preparation from blue crab resided in an approximately 440 kDa fraction. It was inactivated significantly by lipid extraction, but not by proteinase K or glycosidases. The antiviral mechanism of the inhibitor from the blue crab was inhibition of virus attachment to eukaryotic cells, as evidenced by inhibitory activity at 4 degrees C. These studies are among the first to show the existence of broadly active antiviral activities in aquatic crustaceans. These antiviral substances may function as innate host defenses in these species that lack specific antibody immunity and, therefore, merit further study.

Animals↗