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Biomedical subjects

J Pan

Publications and source records attributed to J Pan.

At least 199 records · Page 11Linked to original sources
PubMed1997

Mitochondrial damage by a new antitumour agent furanonaphthoquinone derivative in human cervical cancer HeLa cells.

The intracellular ultrastructural changes induced by the new antitumour agent 2-methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) were investigated in human cervical cancer HeLa cells in comparison with normal cervix cells. The normal cells were isolated from cervixes surgically resected from myoma patients and were keratin positive. FNQ3 at 3-5 micrograms ml-1 selectively damaged the HeLa cell mitochondria followed by rough-surfaced endoplasmic reticulum resulting in cell death. In contrast, normal cells remained unaffected at that concentration but were damaged by 20 micrograms ml-1 FNQ3. The FNQ3-induced tumour cell toxicity was inhibited 52% and 36% by trolox and a water-soluble fraction of the antioxidative substance AOB, respectively. The results indicated that FNQ3 is selectively toxic to HeLa cells at approximately eight times that of normal cells in terms of mitochondrial alteration and free radical formation.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Patterns of gastric myoelectrical activity in human subjects of different ages.

The aim of this study was to investigate the developmental change of gastric myoelectrical activity in humans. Five groups of healthy subjects were studied, including 10 preterm newborns, 8 full-term newborns, 8 full-term infants (ages 2-6 mo), 9 children (ages 4-11 yr), and 9 adults. Gastric myoelectrical activity was recorded using surface electrogastrography for 30 min before and 30 min after a test meal in each subject. Spectral analysis methods were applied to compute the parameters of the electrogastrogram (EGG). The results showed that the percentage of 2- to-4-cycles/min (cpm) slow waves was 26.6 +/- 3.9% in the preterm newborns, 30.0 +/- 4.0% in full-term newborns, 70 +/- 6.1% in 2- to 6-mo-old infants (P < 0.001 compared with newborns), 84.6 +/- 3.2% in 4- to 11-yr-old children (P < 0.03 compared with infants), and 88.9 +/- 2.2% in the adults (P > 0.05 compared with children). In conclusion, gastric slow waves are absent at birth, and there is a maturing process after birth. Age-matched controls are necessary for the interpretation of EGG data from neonates and infants, whereas EGG data in children are the same as in adults.

Adult↗
PubMed1997

Role of angiotensin II in activation of the JAK/STAT pathway induced by acute pressure overload in the rat heart.

This study was designed to determine whether the JAK/STAT (indicating just another kinase/signal transducer and activator of transcription) pathway is activated in cardiac hypertrophy induced in vivo by pressure overload in rats and to demonstrate whether angiotensin II is involved in the activation of the JAK/STAT pathway. Acute pressure overload was produced by constricting the abdominal aorta of Wistar rats. Immunoprecipitation-Western blot analysis revealed that pressure overload activated JAK1, JAK2, and Tyk2 as early as 5 minutes and that STAT1, STAT2, and STAT3 were tyrosine-phosphorylated rapidly after exposure to the pressure overload. Phosphorylation of STAT1 and STAT2 peaked in the early stage at 5 to 15 minutes, whereas that of STAT3 peaked in the late stage at 60 minutes. Gel mobility shift of the interferon gamma activation site/interferon alpha-stimulating response element was observed immediately after the aortic banding, whereas the band of sis-inducing element was shifted in the late stage at 60 minutes. Both cilazapril (angiotensin II-converting enzyme inhibitor) and E4177 (angiotensin II type 1 [AT1] receptor antagonist) significantly suppressed the phosphorylation of Tyk2 and partially inhibited the phosphorylation of JAK2, but neither affected JAK1. Coimmunoprecipitation of the AT1 receptor with JAK2 or Tyk2 was clearly observed at 5 minutes and peaked at 15 minutes (20-fold the control value). These results indicate that the JAK/STAT pathway is activated by acute pressure overload in rats and that angiotensin II is involved in activating Tyk2, and partially activating JAK2, via the AT1 receptor. Both angiotensin II-dependent and -independent pathways take part in activating the JAK/STAT pathway in the pressure-overloaded rat heart.

Acute Disease↗
PubMed1997

Leukemia inhibitory factor, a potent cardiac hypertrophic cytokine, activates the JAK/STAT pathway in rat cardiomyocytes.

Leukemia inhibitory factor (LIF) is a member of the interleukin-6 family of cytokines, which induces a wide range of responses in a variety of cells. The aim of this study was to investigate whether LIF induces cardiomyocyte hypertrophy and transmits signals through the JAK/STAT (indicating just another kinase/signal transducer and activator of transcription) pathway in primary cultured neonatal rat cardiomyocytes. LIF increased protein content and [3H]phenylalanine uptake in cardiomyocytes in a dose-dependent manner. LIF (10(3) U/mL) induced rapid tyrosine phosphorylation of gp130, JAK1, JAK2, STAT1, and STAT3 but not Tyk2 or STAT2. LIF also induced autokinase activity of JAK1 in a time-dependent manner. Gel shift assays for interferon gamma activation site/interferon-stimulated responsive element and sis-inducible element (SIE) revealed that LIF induced dimerization of STAT1 and STAT3 and formation of sis-inducing factor complexes, which subsequently interacted with SIE in the promoter. Preincubation with anti-STAT1 and anti-STAT3 antibodies inhibited the binding of SIF complexes. In conclusion, LIF induces cardiac hypertrophy and directly stimulates the JAK/STAT pathway in cardiomyocytes.

Animals↗
PubMed1997

Proton spectroscopic imaging at 4.1 tesla in patients with malformations of cortical development and epilepsy.

We used proton magnetic resonance spectroscopic imaging (MRSI) at 4.1 tesla in patients with malformations of cortical development (MCDs) and epilepsy. We compared the spectroscopic results with normative data using 2 SDs (95% confidence) above normal values for detection of significant abnormalities for creatine-N-acetylated compounds (Cr/NA) ratio and choline-N-acetylated compounds (Cho/NA). The results were correlated with clinical, EEG, and histologic findings. Patients with focal cortical dysplasia showed significant metabolic abnormalities in correspondence with the structural lesions, whereas patients with heterotopia and polymicrogyria demonstrated no subcortical MRSI abnormalities. Significant correlations were found between the metabolic abnormalities and the frequency of seizures but not with the degree of interictal EEG discharges. Quantitative neuronal and glial cell counts revealed no statistically significant correlation between cell loss and the abnormal metabolic ratios in those who underwent surgery. These preliminary findings suggest that MRSI-based metabolic abnormalities in patients with MCDs are variable and are likely to be associated with complex cellular mechanisms involving the regulation of NA, total Cr content, and Cho.

Acetylation↗
PubMed1997

Evidence of increased endogenous carbon monoxide production in newborn rat endotoxicosis.

Carbon monoxide is thought to serve as a new endogenous mediator in the pathogenesis of sepsis and septic shock. In newborn rat endotoxicosis, carbon monoxide levels in the circulation as well as liver, kidney and lung were found to be significantly increased (P < 0.05). Moreover, the elevations of carbon monoxide correlated with enhanced nitric oxide production as indicated by nitrite/nitrate levels (P < 0.05). Our present data showed for the first time that endogenously produced carbon monoxide was increased during the course of shock-like states, which suggested that the role of carbon monoxide in sepsis and septic shock might worth further study.

Animals↗
PubMed1997

[Soft tissue profile changes following surgical correction for Chinese adults with maxillary protrusion].

The soft tissue profile response to anterior maxillary osteotomy for anterior maxillary excess patients was evaluated. Soft tissue change to hard tissue change ratios as well as linear regression equation were calculated from a patient pool representing fifteen anterior maxillary osteotomies. The soft tissue profile response to anterior maxillary osteotomy appeared to be predictable. The results led to the following abbreviated conclusion: posterior movement of subspinale was accompanied by posterior movement of 37% (r = 0.73) at subnasale, 63% (r = 0.87) at superior labial sulcus. Posterior movement of incision superius was accompanied by posterior movement of 75% (r = 0.86) at labrale superius.

Adult↗
PubMed1997

[Extraction-flame atom absorption determination of trace copper, zinc, cadmium and iron in bones].

Trace content of Cu, Zn, Cd and Fe in bones is determined by flame atomic absorption spectrometry after preceding preconcentration using the extraction system O-phenanthroline-sodium perchlorate/1, 2-dichloroethane. Also, the factors of influence were studied. The method was simple, accurate and reliable, The detection limits were Cu: 0.038microg/ml, Zn: 0.0042microg/ml, Cd: 0.0019microg/ml, Fe: 0.02microg/ml. The recovery rate was between 92.8 and 105%.

Analytic Sample Preparation Methods↗
PubMed1997

[The alignment of the optical system for 216 coude focus echelle spectrometer].

This paper gives a brief introduction about the structure of the echelle spectrometer which was installed at coude focus of the chinese 2. 16 meter astronomical telescope. According to the design requirment of this echelle spectrometer, the main points and steps of alignment of optical system are analysed. Authors work out a practical alignment scheme in which the fewest auxiliary tools are used.

English Abstract↗
PubMed1997

[The change of trace elements content in hair during the period of gestation].

Study on trace elements content change in hair during the period of gestation for 52 lying-in women was performed. The quantitative results for 7 elements have been obtained and the change tendencies for other 7 elements without standard value have been observed on the basis of a self comparison method for each individual.

Female↗
PubMed1997

[Microsurgical restoration of foot tissue defects].

From 1984 to 1994, 236 different types of traumatic defects of foot were repaired by microsurgical tissue grafting. They included simple cutaneous flap in 187 and composite flap in 49. Among the 236 different tissue flaps, vascularized flap was used in 97 and pedicled flap in 139. The 4 fore-foot and 6 heel defects were repaired by composite skeleted cutaneous grafts with scapula and vascularized febula respectively. After the follow-up from 1 to 10 years, all the grafted tissues were survived and healed well. The functions were satisfactory, and 186 patients had resumed their original works. The key to good function following repair was to maintaion the integrity of foot structures and the sensation of the sole and heel.

Adolescent↗
PubMed1996

Transformation of epithelial cells stably transfected with H2O2-generating peroxisomal urate oxidase.

Peroxisome proliferators, a group of structurally diverse nongenotoxic agents, induce predictable pleiotropic responses in liver, including the development of liver tumors in rats and mice. These agents transcriptionally activate the three genes of the peroxisomal beta oxidation enzyme system by interacting with the peroxisome proliferator-activated receptor(s). It has been proposed that H2O2 generated by the peroxisomal beta oxidation system leads to DNA damage and neoplastic transformation. Consistent with this hypothesis is that cells stably transfected with H2O2-generating peroxisomal fatty acyl-CoA oxidase cDNA, which encodes the first and rate-limiting enzyme of the beta oxidation system, undergo transformation in the presence of a fatty acid substrate. To test whether H2O2 generated by other peroxisomal oxidases can also lead to transformation, a full-length cDNA encoding rat urate oxidase (UOX), which oxidizes uric acid to allantoin and in the process generates H2O2, was introduced into African green monkey kidney cells (CV-1 cells) under the control of constitutively active human peroxisomal fatty acyl-CoA oxidase gene promoter. Five stably transfected CV-1 cell lines expressing recombinant rat UOX were isolated in which the recombinant protein was targeted to peroxisomes and formed crystalloid structures or cores similar to those present in rat liver peroxisomes. Increased levels of H2O2 were found when cells stably expressing UOX were exposed to the substrate uric acid. These five clones, designated A-U1 to A-U5, exhibited anchorage-independent growth, as demonstrated by the formation of transformed colonies in soft agar in proportion to the duration of exposure to uric acid. These transformants exhibited clonal growth under serum-deprived conditions. One of these transformed cell lines, the A-U3 cell line, was evaluated for tumorigenicity by s.c. injection in nude mice. All five mice injected with transformed A-U3 cells developed adenocarcinomas, but no tumors developed in mice injected with control CV-1 cells or cells stably expressing UOX that were not exposed to uric acid. These results provide further evidence indicating that sustained overexpression of a peroxisomal H2O2-generating oxidase causes cell transformation.

Animals↗
PubMed1996

Analysis of rate-determining conformational changes during self-splicing of the Tetrahymena intron.

RNA catalyzed reactions are often limited in vitro by the rate of structural rearrangements in the RNA. Analysis of intra- and intermolecular splicing of the Tetrahymena preribosomal RNA revealed two well resolved kinetic phases with rate constants of approximately 2.5 and 0.02 min-1 at 30 degrees C. The data are consistent with a model in which the second phase results from slow refolding of the pre-rRNA. Point mutations result in redistribution of the RNA among different conformations that can be detected by native gel electrophoresis. The active pre-rRNA rapidly progresses to a product complex in the presence of GTP. Release of the ligated exons is slightly slower than splicing at 30 degrees C (0.3 -0.5 min-1). In contrast, the intermediate complex after the first step of splicing dissociates much more slowly (5 x 10(-3) min-1), accounting for the low amount of intron-3' exon intermediate typically seen during splicing of wild type pre-rRNA. These results provide an initial framework for studying conformational changes that accompany excision of the Tetrahymena intron from ribosomal RNA.

Alternative Splicing↗