Biomedical subjects

X Guo

Publications and source records attributed to X Guo.

At least 289 records · Page 16Linked to original sources

PubMed1998

[A study on abnormal chondrocyte differentiation and abnormal expression of collagen types in articular cartilage from patients with Kaschin-Beck disease].

OBJECTIVE: To study the abnormal characteristics of chondrocyte differentiation and abnormal expression of collagen types in articular cartilage from patients with Kaschin kaschin-Beck disease (KBD). METHODS: The abnormal differentiation and expression of collagen types I, II, III, IV and X in articular cartilage from five cases of KBD patients were examined using monoclonal immunohistochemical methods. RESULTS: (1) The expression of tyep II collagen was decreased in the upper zone in KBD articular cartilage. (2) The expression of types I, III and VI collagen were found throughout the articular cartilage, but type X collagen was located in the calcified cartilage zone and around chondrocyte clusters in the deep zone. (3) Chondrocyte clusters exhibited significant pericellular staining for types I, II, III and VI collagen, but did not stain with any collagen antibody in the chondronecrosis areas. CONCLUSION: The abnormal collagen pattern in the articular cartilage of KBD patients was similar to that seen in primary osteoarthritic cartilage, but having more pronounced type I collagen expression in the surface zone and no collagen expression in the chondronecrosis areas.

Adult↗

PubMed1998

Angiotensin II-induced apoptosis in cultured adult rat ventricular myocytes.

Angiotensin II (Ang II)-induced apoptosis was demonstrated for the first time in cultured adult rat ventricular myocytes (ARVMs) isolated by retrograde heart perfusion with Krebs-Henseleit bicarbonate (KHB) buffer containing collagenase and hyaluronidase. ARVMs incubated with 10 mumol/L Ang II for 48 h showed morphological features of apoptosis (cellular shrinkage, condensation of cytoplasm) and a characteristic "ladder" of DNA bands representing integer multiples of the internucleosomal DNA length about 180-200 bp, which became more evident with further incubation up to 72 h. With shorter incubation time (< or = 24 h) or at a lower Ang II concentration (< 10 mumol/L), such changes failed to occur. This effect of Ang II could be abolished by losartan (10 mumol/L), verapamil (1 mumol/L) or staurosporine (10 nmol/L). The above results indicate that Ang II-induced apoptosis in ARVMs may be mainly mediated by Ang II type I (AT1) receptors with [Ca2+]i and protein kinase C (PKC) playing a critical role.

Angiotensin II↗

PubMed1998

[Analysis of paracetamol, caffeine and chlorphenamine maleate in suxiaoshangfeng capsules by capillary gas chromatography].

A simple and rapid method for simultaneous determination of paracetamol, caffeine and chlorphenamine maleate in Suxiaoshangfeng capsule by capillary gas chromatography with n-hexadecane as internal standard has been reported. In the capsule, the three components can be separated on a 5% Ph-Me-Silicone column (2.65 microns x 0.53 mm x 10 m), with programmed column temperature from 180 degrees C to 230 degrees C at 8 degrees C/min, hold 6 min and then 230 degrees C to 260 degrees C at 10 degrees C/min, hold 10 min. Both the injector and FID detetor temperatures were 280 degrees C. N2 flow rate was 3.5 mL/min and H2 35 mL/min. The injection volume was 1 uL with splitting ratio of 1/25. These components were identified by their retention times and quantitatively determined by their peak areas. The calibration curves were, r = 0.9996 for paracetamol, r = 0.9984 for caffeine and r = 0.9996 for chlorphenamine maleate. The linear ranges were 4.0-20 g/L, 0.15-0.75 g/L and 0.080-0.40 g/L, respectively. The average recoveries were 99.62% (RSD = 0.40%, n = 5), 96.46%. (RSD = 1.32%, n = 5) and 98.55% (RSD = 0.65%, n = 5), respectively.

Acetaminophen↗

PubMed1998

[Autonomic nervous activities in patients with obstructive sleep apnea before and during continuous positive airway pressure treatment].

OBJECTIVE: Heart rate power spectral analysis (HRPSA) can provide information of sympathetic and vagus activities. The aim of the study was to investigate nocturnal variations of autonomic nervous system (ANS) before and during continuous positive airway pressure (CPAP) treatment in patients with OSA. METHOD: 56 subjects with severe OSA were recruited to undergo 7-hour nocturnal polysomnography and ECG monitoring in sleep lab before and during CPAP treatment. 30 subjects without OSA were included as controls. Subjects were excluded if they were receiving medications known to influence ANS activities. ANS was evaluated by HRPSA. RESULT: In addition to repeated sleep apneas and oxygen desaturations, mean areas of LF (1 383 +/- 305) and HF (662 +/- 190) in OSA subjects were significantly higher than those in the controls (LF 125 +/- 64, P < 0.001; HF 163 +/- 78, P < 0.001). With effective CPAP treatment, LF (221 +/- 81) and HF (221 +/- 108) decreased remarkably (P < 0.001, separately) and reached the levels of controls (P > 0.05, separately). CONCLUSION: The results suggested that nocturnal ANS activities are abnormal in patients with OSA, especially the enhancement of sympathetic nervous activity. Fluctuation of ANS induced by apnea and oxygen desaturation may explain the association between OSA and cardiovascular diseases. CPAP treatment is effective in improving ANS activities by way of eliminating apnea and reversing hypoxemia.

Adult↗

PubMed1998

[The protective effect of captopril during myocardial ischemia and reperfusion and its mechanism].

OBJECTIVE: To investigate the myocardial protective effect of captopril (Cpl) during ischemia and reperfusion injury. METHODS: Sixteen mongrel dogs were randomly divided into the control and Cpl groups. In the control group, only modified St. Thomas cardioplegia was used. In the Cpl group, St. Thomas cardioplegia and reperfusional blood containing captopril 4.6 mumol/L were used. The plasma renin activity (RA), contents of angiotensin II (AT-II) and endothelin-1 (ET-1) in arterial blood were determined before cardiopulmonary bypass (CPB) and 5, 35, 60 min after reperfusion. The myocardial RA, contents of AT-II, ET-1 and malondyldialdehyde (MDA) were also measured. Parameters of cardiac function were monitored simultaneously. RESULTS: In the control group the plasma RA, AT-II and ET-1 contents were increased after reperfusion and significantly higher than those before CPB (P < 0.01). However, the content of AT-II in the Cpl group was not increased after reperfusion. The content of ET-1 in the Cpl group was increased but significantly lower than that in the control group (P < 0.01). The myocardial AT-II, ET-1 and MDA contents in the Cpl group were significantly lower than those in the control group. The cardiac index (CI) and coronary blood flow (CBF) in the Cpl group regained normal after reperfusion at 35 min. CONCLUSIONS: Cardioplegia and reperfusion blood containing 4.6 mumol/L captopril could ameliorate the cardiac performances by inhibiting myocardial and systemic RAS and decreasing the ET-1 production.

Angiotensin II↗

PubMed1998

[Effect of hypoxia on proliferation and alpha 1 (I) procollagen gene expression by human fetal lung fibroblasts].

OBJECTIVE: The effect of 2% hypoxia on the proliferation and alpha 1(I) procollagen gene expression by human fetal lung fibroblast was studied. METHODS: Cell proliferation was determined by cell counting and nonradioactive cell proliferation assay method. alpha 1(I) procollagen gene expression was detected by Northern blot hybridization analysis. RESULTS: Cell number and 490 nm OD expressing low oxygen values were markedly increased by the 24, 48 and 72 h exposure to 2% hypoxia respectively. An obvious increase of the alpha 1(I) procollagen mRNA expression was detected after 24 h exposure to 2% hypoxia. The increase of gene expression could be inhibited by Ligustrazin (30 micrograms/ml, 10 micrograms/ml). CONCLUSIONS: 2% hypoxia plays an important role in the outcome of wound healing and pulmonary vascular remodeling by affecting the function of human fetal lung fibroblasts.

Cell Division↗

PubMed1998

[Simultaneously monitoring end tidal CO2 and other parameters versus anesthesia management].

OBJECTIVE: To investigate the significance of end tidal CO2(ETCO2) combined with other techniques in anesthesia management. METHODS: Twenty two patients undergoing general anesthesia were monitored with electromyocardiogram (ECG), invasive arterial blood pressure (IABP), plethysmogram and capnography simultaneously. Ten patients undergoing epidural anesthesia and cervical plexus block were monitored with ETCO2. RESULTS: During general anesthesia the depth of general anesthesia, status of ventilation and the degree of muscle relaxation could be grossly evaluated by simultaneously monitoring ETCO2, capnography, plethysmogram, ECG and IABP. ETCO2 could also provide an objective standard for the assessment of respiratory function during spontaneous ventilation. CONCLUSIONS: ETCO2 combined with other monitoring techniques can increase the safety of anesthesia and the accuracy of anesthesia management.

Anesthesia, Epidural↗

PubMed1998

[Experimental study on effect of altitude xishi capsule in treating oleic acid induced lung injury in acute hypoxia rats].

OBJECTIVE: To explore the effect and pathophysiological mechanism of Altitude Xishi Capsule (XSC) on lung injury during acute hypoxia. METHODS: A new model of acute lung injury was established by administering oleic acid into superior vena cava in experimental rat during acute hypoxia, which was formed by putting the animal in a hypobaric room, and reduced the pressure gradually in uniform speed till a simulated environment of 6000 m above sea level was formed and lasted for 12 hours. XSC was given orally to the rat before oleic acid administration. The effect of XSC on the model was observed by determination of PaO2, wet/dry ratio of lung and pathologic examination at 1, 2, 3 and 4 hours separately. RESULTS: The respiratory frequency of model animal increased markedly, with the water content of lung reduced and aggravated as the hypoxia prolonged. XSC could obviously improve the pulmonary edema and inflammatory cell infiltration in lung. CONCLUSIONS: The aforesaid acute lung injury model with successful rate of 100%, it resembles the clinical acute lung injury and was useful for research on pathophysiology and treatment of ARDS or acute lung injury, XSC could improve the oleic acid induced lung injury in hypoxia rats by reducing the pulmonary edema and inflammatory cell infiltration.

Animals↗

PubMed1998

[Isolation and identification of Triterpenoid compounds in the fruits of Chaenomeles lagenaria (Loisel.) Koidz].

OBJECTIVE: The fruit of Chaenomeles lagenaria is a commonly used drug in Chinese traditional medicine. It is especially effective on rheumatism. The current work is to find out the chemical basis of its pharmacological activity. METHOD: All compounds were extracted with organic solvents and separated by silica gel column or thin layer chromatography, and then purified by recrystalization. The structures were elucidated on the basis of chemical reactions and spectral data analysis. RESULT: In addition to the compounds reported in our previous work, three triterpenoid compounds were separated and identified as 3-O-acetyl ursolic acid, 3-O-acetyl pomolic acid and betulinic acid respectively. CONCLUSION: It is obvious that triterpenoid compounds are dominant among the chemical constituents of C. lagenaria. But it is still to be clarified whether they are the chemical basis of the drug's pharmacological activity.

Drugs, Chinese Herbal↗

PubMed1998

[Analysis of Myc gene family in laryngeal cancer].

OBJECTIVE: To study the abnormal amplification and role of Myc gene family in the development of laryngeal cancer. METHOD: A PCR-PAGE-Laser scanning technique was applied. RESULTS: There was no Myc gene amplification in the normal laryngeal tissues. The abnormal L-myc and C-myc gene were positive in 47% (15/32) of laryngeal cancers and 41% (13/32) of the cancers shown the N-myc gene amplification. Myc gene amplification was not related to age, sex and differentiation (P > 0.05), but the N-myc amplification was higher in patients with lymph node metastasis (P < 0.05). CONCLUSION: The N-myc amplification may play a role of positive regulation in the lymph metastasis of laryngeal cancer. The abnormal amplification of Myc gene family is one of the causes in development of laryngeal cancer.

Adult↗

PubMed1998

[Laryngeal reconstruction after near-total laryngectomy].

OBJECTIVE: To reduce the rate of near-total laryngectomy and reconstruct laryngeal function. METHOD: A retrospective review was made on 19 patients treated by near-total laryngectomy and laryngeal reconstruction from 1991 to 1996. Eight patients were male and 11 were female. The age range was from 40 to 74 years, with a mean age of 57.6. Two cases were in stage II, 9 cases stage III, 8 cases stage IV. The characteristic of this operation is to remove hyoid bone and reduce aspiration. RESULTS: Speech function in all patients was good. Deglutition in most patients was good. Five patients breathed through the larynx after decannulation. Fourteen patients respired through tracheostoma because of stenosis of laryngeal cavity. Among them, 10 cases did not need cannula for their wide tracheostomas, 4 cases needed cannula. Three-year survival rate was 78.6%(11/14), 5-year survival rate was 75%(3/4). CONCLUSION: Laryngeal reconstruction near-total laryngectomy is helpful to restore laryngeal function and decrease the rate of total laryngectomy.

Adult↗

PubMed1998

[Determination of resorcinol and salicylic acid in piyanning tincture by high performance liquid chromatography].

A method for the simultaneous determination of resorcinol and salicylic acid in Piyanning tincture by HPLC has been proposed. Operating conditions were Hyppersil ODS column, 4.6 mm x 200 mm, V (methanol): V(water): V(acetic acid) = 50:50:0.9 mobile phase and UV detection at 285 nm. The linear ranges of the method were 0.05-0.25 g/L(r = 1.000) for resorcinol and 0.025-0.127 g/L(r = 1.000) for salicylic acid. The limits of detection were both 0.2 mg/L at a signal-to-noise of 3. The assay method was capable to resolve resorcinol and salicylic acid from their impurities.

Chromatography, High Pressure Liquid↗

PubMed1998

[Extractive chromatograph on-line preconcentration flow injection flame atomic absorption spectrometric determination of trace silver in geological samples].

Extractive chromatograph using a TPP column was applied to preconcentration and matrix separation for trace silver in geological samples. A flow injection on-line method for the determination of silver by flame AAS is described. An enrichment factor of 20 was achieved at a sampling frequeucy of 30 times/h. The precision RSD is 2.0% for the analysis of a geochemical standard reference material (GSD-12, n = 11) and the detection limit obtained (3sigma) is 0.02 microg/g.

English Abstract↗

PubMed1998

Overlapping substrate specificities of cytochrome P450 3A and P-glycoprotein for a novel cysteine protease inhibitor.

K02 (morpholine-urea-Phe-Hphe-vinylsulfone), a newly developed peptidomimetic, acts as a potent cysteine protease inhibitor, especially of cathepsins B and L (which are associated with cancer progression) and cruzain (a cysteine protease of Trypanosoma cruzi, which is responsible for Chagas' disease). Here we investigated features of the disposition of K02 using in vitro systems, characterizing the interaction of the drug with human cytochrome P450 (CYP) 3A and P-glycoprotein (P-gp), a mediator of multidrug resistance (MDR) to cancer chemotherapy and a countertransporter in the intestine that limits oral drug bioavailability. P-gp functions as an ATP-dependent drug efflux pump to reduce intracellular cytotoxic concentrations. An HPLC assay was developed to analyze K02 and its metabolites formed in human liver microsomes. Three major primary metabolites were determined by LC/MS/MS to be hydroxylated products of the parent compound. A rabbit anti-CYP3A polyclonal antibody (200 microl antibody/mg microsomal protein) produced 75-94% inhibition of the formation of these three hydroxylated metabolites. Ketoconazole (5 microM), a selective CYP3A inhibitor, produced up to 75% inhibition, whereas other CYP-specific inhibitors, i.e. quinidine (CYP2D6), 7,8-benzoflavone (CYP1A2), and sulfaphenazole (CYP2C9), showed no significant effects. An identical metabolite formation profile for K02 was observed with cDNA-expressed human CYP3A4 (Gentest). These data demonstrate that K02 is a substrate for CYP3A. Formation of 1'-hydroxymidazolam, the primary human midazolam metabolite, was markedly inhibited by K02 via competitive processes, which suggests the potential for drug-drug interactions of K02 with other CYP3A substrates. K02 significantly inhibited the photoaffinity labeling of P-gp with azidopine and LU-49888, a photoaffinity analogue of verapamil. Transport studies with [14C]K02, using MDR1-transfected Madin-Darby canine kidney cell monolayers in the Transwell system, demonstrated that the basolateral-to-apical flux of K02 across MDR1-transfected Madin-Darby canine kidney cells was markedly greater than the apical-to-basolateral flux (ratio of 63 with 10 microM [14C]K02). This suggests that K02 is also a P-gp substrate. These studies are important for formulating strategies to increase the absorption and/or decrease the elimination of K02 and to optimize its delivery to malignant cells and parasite-infected host cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Activation of the osteopontin promoter by the orphan nuclear receptor estrogen receptor related alpha.

Estrogen receptor related alpha (ERRalpha) is an orphan nuclear receptor that is closely related to the estrogen receptor. It is expressed in a variety of adult and embryonic tissues (in particular, at the onset of ossification), as well as in several osteoblastic cell lines. ERRalpha acts as a site-specific, cell-specific transcriptional activator. Here, we show that ERRalpha transactivates the promoter of the mouse osteopontin (OPN) gene, the product of which is a marker of the late stages of osteoblastic differentiation. This effect is cell specific and is exerted through derivatives of the ERRalpha response element. Overexpression of ERRalpha in three different osteoblast-like cell lines results in an elevation of the amount of OPN-corresponding mRNA. Therefore, OPN is a target gene for ERRalpha, pointing to the role of the latter in osteoblast differentiation.

Animals↗

PubMed1997

Synthetic strategies for the preparation of precursor polymers and of microcapsules suitable for cellular entrapment by polyelectrolyte complexation of those polymers.

The production of microcapsules suitable for the entrapment of mammalian cell by means of polyelectrolyte complexation has, of a necessity, led to the development of novel strategies for the preparation of relatively bioinert polymers which complex efficiently under unique conditions to produce a mechanically resilient membrane with efficient transport properties. In this communication we relate a brief overview of capsule-membrane forming systems for the immunoisolation (or potential immunoisolation) of mammalian cells, which are based upon the complexation of polyelectrolyte (PE) polymers; with emphasis on precursor synthesis and relationships between precursor polymer structure and capsule membrane stability.

Animals↗

PubMed1997

Leukemia inhibitory factor and ciliary neurotrophic factor regulate dendritic growth in cultures of rat sympathetic neurons.

Cytokines such as leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) have previously been shown to regulate neurotransmitter and neuropeptide synthesis in sympathetic neurons [P.H. Patterson, Leukemia inhibitory factor, a cytokine at the interface between neurobiology and immunology, Proc. Natl. Acad. Sci. USA 91 (1994) 7833-7835]. We considered the possibility that these agents may also affect the development of neuronal cell shape. Intracellular dye injection and immunocytochemistry were used to assess dendritic growth in cultures of perinatal rat sympathetic neurons and the effects of LIF and CNTF were compared to those of osteogenic protein-1 (OP-1), a growth factor that induces profuse dendritic growth in these neurons [P. Lein, M. Johnson, X. Guo, D. Rueger, D. Higgins, Osteogenic protein-1 induces dendritic growth in rat sympathetic neurons, Neuron 15 (1995) 597-605]. Under control conditions, sympathetic neurons formed only axons. Exposure to either LIF or OP-1 stimulated dendritic growth, but the magnitude of the response to LIF was much less than that obtained with OP-1 with respect to both dendritic number and length. Simultaneous exposure to LIF and OP-1 resulted in dendritic growth equivalent to that observed in the presence of LIF alone, suggesting that LIF inhibits the response of neurons to OP-1. Both the stimulatory and inhibitory effects of LIF were mimicked by CNTF, but not by other growth factors. These data suggest that LIF and CNTF regulate dendritic development in a complex manner that is dependent on both the morphological state of the neuron and the presence of other growth factors. However, the net effect of exposure to these cytokines appears to be the production of a population of neurons with rudimentary arbors consisting of only one or two short dendrites.

Animals↗

PubMed1997

Human breast cancer cells and normal mammary epithelial cells: retinol metabolism and growth inhibition by the retinol metabolite 4-oxoretinol.

To understand the signaling and growth-inhibitory effects of retinoids, we have examined the metabolism of [3H]retinol in a number of estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) human breast cancer cell lines. We have also assayed the metabolism of [3H]retinol in normal human mammary epithelial cells. The ER+ breast cancer cell lines MCF-7 and T47D produce [3H]4-oxoretinol from [3H]retinol; the production of [3H]4-oxoretinol is increased by initial culture in the presence of nonradiolabeled retinoic acid (RA) or N-(4-hydroxyphenyl)retinamide, indicating that these drugs enhance [3H]retinol metabolism to [3H]4-oxoretinol. No metabolism of [3H]retinol to [3H]RA in these ER+ tumor lines was detected. ER- breast cancer lines MDA-MB-231, MDA-MB-468, and BT20 do not metabolize [3H]retinol to [3H]4-oxoretinol. In the ER- tumor lines, most of the [3H]retinol remains unmetabolized during the 24-h culture period; MDA-MB-468 and BT20 metabolize some [3H]retinol to [3H]RA. Unlike the majority of the tumor lines, the normal human breast epithelial cell strains AD074 and MCF10A rapidly metabolize [3H]retinol to [3H]retinyl esters. No detectable [3H]RA is produced from [3H]retinol in AD074 and MCF10A cells. Thus, the normal breast epithelial strains, the ER+ tumor lines and the ER- tumor lines differ greatly in their pathways of [3H]retinol metabolism. The levels of cellular retinol binding protein-I mRNA expression are not correlated with the levels or types of various retinol metabolites. Whereas the normal breast epithelial cells and the ER+ tumor lines are growth inhibited by RA, N-(4-hydroxyphenyl)retinamide, and 4-oxoretinol, only the 4-oxoretinol is growth inhibitory in the ER- tumor lines. The cellular retinoic acid-binding protein II mRNA levels are not correlated with the growth inhibition by RA or 4-oxoretinol in the normal and tumor lines.

Breast↗