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Biomedical subjects

X Song

Publications and source records attributed to X Song.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Detection of human papillomavirus infection in cervical Pap smears by computer-assisted cytologic test].

OBJECTIVE: The sensitivity and accuracy of cytologic computer-assisted test (CCT) in diagnosis of human papillomavirus (HPV) infection in cervical Pap smear were evaluated. METHODS: Cervical Pap smears obtained from 158 patients with vulva condyloma acuminata were examined by CCT. The diagnostic criteria were based on The Bethesda System (TBS). Simultaneously HPV DNA in cervical mucus was examined by polymerase chain reaction (PCR) technique and cervical biopsy taken under the guidance of colposcopy for pathological examination. RESULTS: The sensitivity and accuracy of CCT in diagnosis of cervical HPV infection were 74.62% and 67.72% compared with pathological results whereas 69.11% and 70.88% compared with PCR results respectively. CONCLUSION: The results indicates that CCT, a cytologic pathological technique, is a useful method in diagnosis of clinical and subclinical cervical HPV infection.

Cervix Uteri↗
PubMed1998

[Correlation of interleukin 1 beta-converting enzyme(ICE) gene expression with gut epithelial cell apoptosis in septic mice].

OBJECTIVE: To investigate the correlation of gut epithelial cell apoptosis with ICE, IL1 beta gene expression in septic mice. METHODS: Sepsis was induced in mice by cecal ligation and puncture(CLP). Sham-operation group underwent the same manipulation but without CLP. 1, 3, 6 hours after CLP, gut epithelial cells, were isolated. IL1 beta, ICE gene expression was detected quantitatively by RT-PCR. Epithelial cell apoptosis was assessed by flow cytometric method and biochemically by DNA electrophoresis. RESULTS: The survival rate of CLP mice was 1/10 as compared to 10/10 of sham-operation mice. IL1 beta, ICE mRNA expression in CLP mice was significantly higher than that in the sham-operation group(P < 0.01); IL1 beta mRNA expression was parallel to ICE mRNA expression. The number of epithelial cell apoptosis was correlated excellently to the level of ICE, IL1 beta mRNA expression. Epithelial cell apoptosis could not be detected in sham-operation group at the indicated time points. CONCLUSION: ICE, IL1 beta gene overexpression may be involved in the vulnerability of epithelial cell apoptosis in septic mice.

Animals↗
PubMed1998

Bcl-2 gene and its family genes Bax, Bcl-Xl as well as Fas/Apo-1 and their clinical significance in acute leukemia.

OBJECTIVE: To study the suppressing genes of apoptosis, namely Bcl-2, its family genes Bax, Bcl-Xl, and the inducing gene of apoptosis Fas/Apo-1. METHODS: The techniques of cytoimmuno-histiochemical stains, Western blotting and Northern blotting were used. RESULTS: It was found that the antigens of Bcl-2 in acute myelogenous leukemia (AML) and acute lymphocytic (ALL) was higher than that in the normal (P < 0.01). At same time, Bcl-2 was obviously lower expression in complete remission (CR) group than that in non-remission (NR) one by retrospective analysis (P < 0.01). Though Bcl-2 was low expression in CR with Western blotting, there was no statistical significance (P > 0.05). In CR group the expression of Bcl-2 mRNA was obviously lower than that of NR one (P < 0.01). Even though leukemia expression of Bax with cytoimmuno-histiochemical stain was also lower than that in the normal people, there was no difference between CR and NR with cytoimmuno-histiochemical, Western blotting and Northern blotting (P > 0.05). There was difference of Bcl-Xl mRNA in two groups (P < 0.01). The expression Fas/Apo-1 in leukemia was lower than that in normal people (P < 0.01). But in CR and NR, there was no difference with cytoimmuno-histiochemical stain and Western blotting. CONCLUSIONS: The Changes of genes and their proteins are significant theoretically and clinically. The antigen expression of Bcl-2 and the expression of Bcl-2 mRNA may be considered as a prognostic index for AML.

Adaptor Proteins, Signal Transducing↗
PubMed1998

[Nasopharyngeal carcinoma and dermatomyositis (analysis of 12 cases)].

The onset relationship between dermatomyositis (DM) and malignant tumor, especially nasopharyngeal carcinoma (NPC), was approached. Approximately 90 cases of DM were admitted in the hospital. Among them 15 cases were complicated with malignant tumor of which 12 cases were complicated with NPC (account for 80% of DM with complicated carcinoma). In addition to treat these patients with prednisone and antibiotics, radiation therapy has been applied for NPC and metastasis in the neck. During the hospitalizations, one patient died, eleven patients' NPC was controlled, and the DM was completely resolved or improved. There is an obvious relationship between DM and carcinoma. DM may improve or even subside with good short term prognosis, as long as the carcinoma is controlled successfully.

Adult↗
PubMed1998

[Phacoemulsification for mature or hypermature cataracts].

OBJECTIVE: To discuss how to choose the methods of capsularhexis and phacoemulsification in cases with mature or hypermature cataract. METHODS: On fifty-nine mature or hypermature cataract patients, continuous circular capsularhexis or can-opener capsulotomy was performed. The nucleus was emulsified by the method of divide and conquer or phaco chop or rotatory carousel in the bag or at the plane of iris. RESULTS: Continuous circular capsularhexis was successful in 51 cases, failed or shifted to can-opener in 8 cases. There were posterior capsular rupture in 1 cases, partial dehiscence of the zonule in 1 cases and iris bitten by the phaco tip in 1 cases. Postoperatively, there were mild corneal edema in 6 cases and iris posterior synechia in 1 cases. CONCLUSION: Continuous circular capsularhexis is the key point to obtain a successful phacoemulsification for mature or hypermature cataract. Hydrodissection is not important before the phacoemulsification. Skillful phaco chop can reduce the surgical manipulation and the postoperative reaction.

Aged↗
PubMed1998

Alterations of cytoskeletal tau protein of SH-SY5Y human neuroblastoma cells after exposure to MPTP.

In this study, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 10(-3) to 10(-4) M for 2 to 5 days) increased the expression of microtubule-associated tau protein in both the supernatant and pellet fractions of lysed SH-SY5Y human neuroblastoma cells. The western blot using anti-tau-1 antibodies demonstrated that the cells contained at least six isoforms of tau proteins, five with molecular weights from 45 to 62 kD. Reverse transcriptase polymerase chain reaction (RT-PCR) using primers coding whole length tau protein further confirmed the presence of tau in SH-SY5Y cells. The PCR product of tau in SH-SY5Y cells had approximately 1050 base pairs. MPTP caused an increased expression of the PCR product of tau, suggesting that the toxicant caused an increase in mRNA coding the tau protein. The expression of cytoskeletal tau protein may, therefore, provide a marker for MPTP neurotoxicity in SH-SY5Y cells.

Cytoskeletal Proteins↗
PubMed1998

Experimental study on the scavenging effects of ginsenosides on oxygen free radicals using model of heterotopic heart transplantation in rats.

Oxygen-derived free radicals play an important role in myocardial injury associated ischemia and reperfusion. To investigate whether ginsenosides, as an additive agent of cardioplegic solution, can decrease toxicity of oxygen free radicals in myocardial injury, a heterotopic heart transplantation model in Wistar rats was employed. St. Thomas II cold cardioplegia containing ginsenosides 80 mg/l was used in the experimental group. St. Thomas II cold cardioplegia alone was used in the control group. After global ischemia for 60 minutes and reperfusion for 30 minutes of a transplanted heart, SOD activity in the myocardium treated with ginsenosides was significantly higher than that in the control group (N=10, p< 0.01), whereas the MDA in the myocardium treated with ginsenosides were markedly lower than that of the control group (p< 0.01). The amounts of oxygen free radicals in the myocardium treated with ginsenosides were significantly lower than that of the control group (p <0.001). This study demonstrates that ginsenosides, as a proper additive agent of cardioplegic solution, can decrease toxicity of oxygen free radicals, suggesting one of the mechanisms for its protective effects against myocardial ischemia and reperfusion injury.

Animals↗
PubMed1997

Relative functions of the alpha and beta subunits of the proteasome activator, PA28.

PA28 is a 180,000-dalton protein that activates hydrolysis of small nonubiquitinated peptides by the 20 S proteasome. PA28 is composed of two homologous subunits, alpha and beta, arranged in alternating positions in a ring-shaped oligomer with a likely stoichiometry of (alphabeta)3. Our previous work demonstrated that the carboxyl terminus of the alpha subunit was necessary for PA28 to bind to and activate the proteasome. The goals of this work were to define the exact structural basis for this effect and to determine the relative roles of the alpha and beta subunits in proteasome activation. Each subunit and various mutants of the alpha subunit were expressed in Escherichia coli and purified. PA28alpha stimulated the proteasome, but had a much greater Kact than native heteromeric PA28. In contrast, PA28beta was unable to stimulate the proteasome. Mutants of the alpha subunit in which the carboxyl-terminal tyrosine residue was deleted or substituted with charged amino acids could neither bind to nor activate the proteasome. However, substitution of the carboxyl-terminal tyrosine with other amino acids resulted in proteins which could stimulate the proteasome to various extents. Tryptophan mutants stimulated the proteasome as well as did native PA28, whereas serine or phenylalanine mutants stimulated the proteasome much poorer than did wild type PA28alpha. Deletion of the "KEKE" motif, a 28-amino acid domain near the amino terminus of PA28alpha, had no effect on proteasome stimulatory activity. Hetero-oligomeric PA28 proteins were reconstituted from isolated wild type and mutant subunits. PA28 reconstituted from wild type subunits had structural and functional properties that were indistinguishable from those of the native hetero-oligomeric protein. PA28 molecules reconstituted from inactive alpha subunits and wild type beta subunits remained inactive. However, PA28 molecules reconstituted from suboptimally active alpha mutants and wild type beta subunits had the same activity as native heteromeric PA28. These results indicate that the beta subunit modulates PA28 activity, perhaps by influencing the affinity of PA28 for the proteasome.

Animals↗
PubMed1997

Tumor necrosis factor alpha plays a central role in immune-mediated clearance of adenoviral vectors.

Adenovirus (Ad) gene transfer vectors are rapidly cleared from infected hepatocytes in mice. To determine which effector mechanisms are responsible for elimination of the Ad vectors, we infected mice that were genetically compromised in immune effector pathways [perforin, Fas, or tumor necrosis factor alpha (TNF-alpha)] with the Ad vector, Ad5-chloramphenicol acetyl transferase (CAT). Mice were sacrificed at 7-60 days postinfection, and the levels of CAT expression in the liver determined by a quantitative enzymatic assay. When the livers of infected mice were harvested 28 days postinfection, the levels of CAT expression revealed that the effectors most important for the elimination of the Ad vector were TNF-alpha > Fas > perforin. TNF-alpha did not have a curative effect on infected hepatocytes, as the administration of TNF-alpha to infected severe combined immunodeficient mice or to infected cultures in vitro had no specific effect on virus persistence. However, TNF-alpha-deficient mice demonstrated a striking reduction in the leukocytic infiltration early on in the infection, suggesting that TNF-alpha deficiency resulted in impaired recruitment of inflammatory cells to the site of inflammation. In addition, the TNF-deficient mice had a significantly reduced humoral immune response to virus infection. These results demonstrate a dominant role of TNF-alpha in elimination of Ad gene transfer vectors. This result is particularly important because viral proteins that disable TNF-alpha function have been removed from most Ad vectors, rendering them highly susceptible to TNF-alpha-mediated elimination.

Adenoviridae↗
PubMed1997

A GTPase-activating protein for the G protein Galphaz. Identification, purification, and mechanism of action.

A GTPase-activating protein (GAP) specific for Galphaz was identified in brain, spleen, retina, platelet, C6 glioma cells, and several other tissues and cells. Gz GAP from bovine brain is a membrane protein that is refractory to solubilization with most detergents but was solubilized with warm Triton X-100 and purified up to 50,000-fold. Activity is associated with at least two separate proteins of Mr approximately 22,000 and 28,000, both of which have similar specific activities. In an assay that measures the rate of hydrolysis of GTP pre-bound to detergent-soluble Galphaz, the GAP accelerates hydrolysis over 200-fold, from 0.014 to 3 min -1 at 15 degrees C, or to >/=20 min-1 at 30 degrees C. It does not alter rates of nucleotide association or dissociation. When co-reconstituted into phospholipid vesicles with trimeric Gz and m2 muscarinic receptor, Gz GAP accelerates agonist-stimulated steady-state GTP hydrolysis as predicted by its effect on the hydrolytic reaction. In the single turnover assay, the Km of the GAP for Galphaz-GTP is 2 nM. Its activity is inhibited by Galphaz-guanosine 5'-O-thiotriphosphate (Galphaz-GTPgammaS) or by Galphaz-GDP/AlF4 with Ki approximately 1.5 nM for both species; Galphaz-GDP does not inhibit. G protein betagamma subunits inhibit Gz GAP activity, apparently by forming a GTP-Galphazbetagamma complex that is a poor GAP substrate. Gz GAP displays little GAP activity toward Galphai1 or Galphao, but its activity with Galphaz is competitively inhibited by both Galphai1 and Galphao at nanomolar concentrations when they are bound to GTPgammaS but not to GDP. Neither phospholipase C-beta1 (a Gq GAP) nor several adenylyl cyclase isoforms display Gz GAP activity.

Animals↗
PubMed1997

Adsorption Enthalpy and Adsorption Isotherm of Tetradecylpyridinium Bromide on Na-Montmorillonite

The adsorption enthalpy and the adsorption isotherm of tetradecylpyridinium bromide (TPB) onto a Na-montmorillonite suspension and the dilution enthalpy of the TPB solution have been determined at 298.15 K. The dilution process is endothermic and the adsorption process is exothermic. For ion exchange adsorption, the interaction between TP+ and the montmorillonite is much stronger than that between Na+ and the montmorillonite because the cumulative adsorption enthalpy increases dramatically with adsorption amount. For molecular adsorption, however, the interaction between TPB and the clay is much weaker.

Journal Article↗
PubMed1997

Cellular mechanisms for developmental toxicity of chlorpyrifos: targeting the adenylyl cyclase signaling cascade.

Developmental neurotoxicity caused by chlorpyrifos exposure is generally thought to target cholinesterase but chlorpyrifos may also act on cellular intermediates, such as adenylyl cyclase, that serve global functions in the coordination of cell development. In the current study, neonatal rats were exposed to apparently subtoxic doses of chlorpyrifos (no weight loss, no mortality) either on Postnatal Days 1-4 or on Postnatal Days 11-14, and the effects on components of the adenylyl cyclase cascade were evaluated in brain regions that are enriched (forebrain) or sparse (cerebellum) in cholinergic innervation, as well as in a nonneural tissue (heart). In all three, chlorpyrifos evoked deficits in multiple components of the adenylyl cyclase cascade: expression and activity of adenylyl cyclase itself, functioning of G-proteins that link neurotransmitter and hormone receptors to cyclase activity, and expression of neurotransmitter receptors that act through this cascade. Disruption of signaling function was not restricted to transduction of cholinergic signals but rather extended to adrenergic signals as well. In most cases, the adverse effects were not evident during the immediate period of chlorpyrifos administration, but appeared after a delay of several days. These results suggest that chlorpyrifos can affect cell development by altering the activity and reactivity of the adenylyl cyclase signaling cascade, a major control point for trophic regulation of cell differentiation. The effects are not restricted to cholinergic targets, nor even to the central nervous system. Hence, disruption of cell development by chlorpyrifos is likely to be more widespread than previously thought.

Adenylyl Cyclases↗
PubMed1997

Elevation of protein kinase C in thyrocytes isolated from a Lewis rat model of autoimmune thyroiditis prevents assembly of immunodetectable connexin43 gap junctions and reduces intercellular communication.

In the Lewis rat model of experimental autoimmune thyroiditis (EAT), decreased immunodetectable connexin assembly into gap junctions and diminished intercellular communication are associated with the loss of thyroid function (hypothyroidism) that occurs prior to significant tissue destruction. The current study explores the hypothesis that the loss of connexin 43 (Cx43)-mediated intercellular communication in these cells is caused by upregulation of protein kinase C (pKC) activity. Thyrocytes isolated from EAT rats exhibited a 78% increase in basal pKC activity; whereas, basal protein kinase A (pKA) activity was unchanged. Increased pKC activity was a result of increased isozyme protein levels. Thyroid cells expressed pKC isozymes gamma and lambda and had elevated levels of alpha (40%), beta (30%), delta (31%), and epsilon (25%) as quantified by western blot analyses. Furthermore, modulation of pKC activity inversely altered Cx43 assembly and function in monolayer thyrocytes. For example, octoacetyl glycerol (OAG) treatment of normal thyrocyte monolayers to increase pKC activity resulted in deficient Cx43 gap junction assembly and reduced intercellular communication indistinguishable from the deficits in EAT thyrocytes. Conversely, calphostin C inhibition of pKC activity in EAT thyrocyte monolayers restored these parameters to normal. Thus, pharmacological modulations of pKC activity in cultured thyrocytes support a causal relation between the changes in pKC activity and Cx43-mediated intercellular communication. Abnormalities in autoimmune diseased thyroid tissue (eg, increased pKC) appear to contribute to reduced intercellular coordination of thyroid follicles and thereby can affect subsequent thyroid function. The persistence of target cell abnormalities in the absence of infiltrating lymphocytes and their products supports an alternative mechanism by which thyroid function can be affected that does not depend on the loss of thyroid glandular epithelium.

Animals↗
PubMed1997

Thermal relations of metabolic rate reduction in a hibernating marsupial.

We tested whether the reduction of metabolic rate (MR) in hibernating Cercartetus nanus (Marsupialia, 36 g) is better explained by the reduction of body temperature (Tb), the differential (delta T) between Tb and air temperature (Ta), or thermal conductance (C). Above the critical Ta during torpor (Ttc) of 4.8 +/- 0.7 degrees C where the Tb was not regulated, the steady-state MR was an exponential function of Tb (r2 = 0.92), and the overall Q10 was 3.3. However, larger Q10 values were observed at high Tb values during torpor, particularly within the thermoneutral zone (Q10 = 9.5), whereas low Q10 values were observed below Tb 20 degrees C (Q10 = 1.9). The delta T did not change over Ta 5-20 degrees C, although MR fell, and therefore the two variables were not correlated. Below the Ttc, Tb was regulated at 6.1 +/- 1.0 degrees C and MR increased proportionally to delta T. Our study suggests that MR in torpid C. nanus is largely determined by temperature effects and metabolic inhibition. In contrast, delta T explains MR only below the Ttc and C appears to affect MR only indirectly via changes of Tb, suggesting that delta T and C play only a secondary role in MR reduction during hibernation.

Animals↗
PubMed1997

[Image analysis of the microvascular permeability to various molecular weight of flucrescein in rat mesentery].

An intravital fluorescence microscopic method and digital image analysis were established for measuring the changes of fluorescein sodium (FINa, MW 376) and FITC-Dextrans (FD-4, MW4000, FD-150, MW150000) permeability in mesenteric microvessels. The transport of various molecular fluorescent tracer within the blood vessels and through the vessel walls into the perivascular tissue of the rat mesentery was studied using a highly sensitive CCD camera, the fluorescence intensities were transformed into video signals and recorded for subsequent analysis. The results showed that FINa could pass through the wall of microvessels very quickly. The diffusion constant was 3.362 x 10(-8) cm2/s with FINa, and FD-4 was 1.718 x 10(-8) cm2/s, FD-150 was 0.0486 x 10(-8) cm2/s. The diffusion constant depended very strongly on the molecular weight and showed no difference between capillary and vessels of the venous part of the microcirculation, but in vessels of the arterial part of microcirculation no diffusion was found. That was to say that diffusion occurred in capillary and microvenous, but not in microarterial. It is expected that this method would be very useful for the quantitive analysis in various molecular weights and in monolayer endothelial cell permeability.

Animals↗
PubMed1997

[Vitrectomy for extraction of intraocular foreign bodies].

OBJECTIVE: To evaluate the effect of treatment of intraocular foreign bodies (IOFBs) with vitrectomy and its influential factors. METHODS: A retrospective research was done on 517 in-patients having undergone extraction of IOFBs with vitrectomy. RESULTS: Postoperatively, the successful rate of the extraction of IOFBs was 97.6%, the rate of cases with useful vision (0.05 to 0.4) increased from preoperative 12.5% to 23.2% and that with good vision (0.5 and better) from 7.2% to 17.0% (P < 0.005). When IOFBs were located in anterior segment, vitreous and retina, the increasing rates of cases with useful vision respectively were 44.4%, 25.1% and 10.7%, and that of good vision were 26.3%, 12.7% and 2.7%. CONCLUSIONS: Vitrectomy is favorable for the extraction of IOFBs, the increase of postoperative vision and the management of complications.

Adolescent↗
PubMed1997

[The relationship between the prognosis of retinoblastoma and proliferating cell nuclear antigen and argyrophilic protein at nucleolus organizer regions].

OBJECTIVE: To investigate the relationship between the proliferative activity of retinoblastoma (Rb) cells and the prognosis of the tumor. METHODS: Proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizer regions (AgNORs) in paraffin-embedded Rb specimens from 48 cases were detected by LSAB immunohistochemical method using an anti-PCNA monoclonal antibody and the technique of ploton. RESULTS: The PCNA labeling index (PCNALI) and the AgNORs counts were well correlated (r = 0.647, P < 0.001). In 29 patients of the 48 cases receiving simple eyeball extirpation and being followed up for 5 years, the mean PCNALI and the mean numbers of AgNORs per nucleus in 19 patients surviving > or = 5 years after operation were markedly lower than that in 10 patients surviving < 5 years after operation (P < 0.01, P < 0.05). CONCLUSION: It is indicated that the PCNALI or the AgNOR count is negatively related with the clinical prognosis of Rb patients, and can be useful in judging the prognosis.

Eye Enucleation↗