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X Tao

Publications and source records attributed to X Tao.

At least 19 recordsLinked to original sources
PubMed2006

Biotransformation of letrozole in rat liver microsomes: effects of gender and tamoxifen.

The in vitro metabolic kinetics of letrozole were investigated by incubating letrozole (10-500 microM) in female or male rat liver microsomes to assess the effect of gender and to predict the in vivo biotransformation characteristics of letrozole in rats. The effects of tamoxifen (TAM) on the metabolic kinetics of letrozole were also examined by incubating letrozole in female rat liver microsomes in the presence or absence of TAM. The effects of chronic pretreatment of female rats with TAM (0.5, 1.0, 5.0 mg/kg/day, i.p. for 7 consecutive days) on liver microsomal protein content and metabolic activity were also examined. The formation rate of the carbinol metabolite of letrozole, CGP44 645, was significantly higher (p<0.05) in male rat liver microsomes in comparison to female. The V(max)/K(m) ratio for letrozole metabolism in female rat liver microsomes did not change significantly (p>0.05) in the presence of TAM. After chronic pretreatment of female rats with TAM (up to a dose of 1.0mg/kg/day), the hepatic microsomal protein content was significantly increased but the formation rate of CGP44 645, when normalized for protein content, did not change significantly. These results suggest that there is a marked gender difference in letrozole metabolism in rats. It also appears that acute treatment of female rat liver microsomes with TAM produces negligible inhibitory effect on the CYP mediated metabolic clearance of letrozole. However, chronic pretreatment of female rats with TAM appear to induce CYPs, but does not significantly impact the metabolic activities of the enzymes associated with the formation of the carbinol metabolite of letrozole.

Animals↗
PubMed2006

The effect of tamoxifen on the pharmacokinetics of letrozole in female rats.

The effects of single doses of tamoxifen (TAM; 0.5-5 mg/kg, i.v.) and chronic pretreatment with TAM (0.1-5.0 mg/kg/day, i.p. for 7 consecutive days) on letrozole (0.5 mg/kg, i.v.) pharmacokinetics were evaluated in female Sprague-Dawley rats. The plasma concentration-time profiles of letrozole (0.1-2.0 mg/kg) after single i.v. doses were analysed by the non-compartment model with terminal half-lives (t(1/2,lambdaz)) ranging from 34.3 to 37.5 h. The volume of distribution at the terminal phases (Vd(lambdaz)) ranged from 1.9 to 2.1 l/kg and clearance (CL) varied from 0.036 to 0.042 l/(h.kg). After co-administration of TAM and letrozole intravenously, the t1/2, Vd(lambdaz) and CL of letrozole were not significantly altered. Chronic pretreatment with TAM significantly decreased the t1/2 of letrozole by about 33%, and increased its clearance by an average of 40%. However, TAM pretreatment did not significantly affect the Vd(lambdaz) of letrozole in female rats. Co-administration of letrozole and TAM orally increased the absorption half-life of letrozole threefold although the absolute bioavailability remained unchanged. These observations suggest that single oral doses of TAM delay the absorption of letrozole while chronic pretreatment with TAM accelerates the elimination of letrozole, probably due to induction of cytochrome P450 enzymes in rats.

Animals↗
PubMed2006

Responses of thyroid hormones of market-size broilers to thermoneutral constant and warm cyclic temperatures.

This study characterizes the responses, particularly diurnal variations, of thyroid hormones (TH) [3,5,3'-triiodothyronine (T3), thyroxine (T4), and T3:T4 ratio (T3/T4)] of Arbor Acres broilers to constant thermoneutral (TN) or warm cyclic (WC) temperatures. There existed distinct circadian variations--2 peaks in TH under the TN and WC conditions. The 2 peaks of T3, T4, and T3/T4 of the broilers occurred, respectively, at 0 and 16 h, 8 and 16 h, and 0 and 12 h under the TN condition; but at 0 and 12 h, 0 and 8 h, and 4 and 12 h under the WC conditions. During a 5-d heat exposure (HE) to the WC regimens, T3 and T4 showed continual decrease. The daily mean of T3 declined significantly (P < 0.05) on the first day of HE, whereas significant decrease of T4 (P < 0.05) occurred on the second day of HE. There was no significant change in daily mean of T3/T4 during the same HE period. Hence, results of the study indicate that T3 provides a better heat stress indicator than T4. The nature of circadian variations in TH makes it necessary to collect blood samples more than once a day, e.g., 6 times at 0, 4, 8, 12, 16, and 20 h, to ensure full evaluation of hormonal responses of market-size broilers undergoing thermal challenges.

Animals↗
PubMed2005

Secretin differentially sensitizes rat pancreatic acini to the effects of supramaximal stimulation with caerulein.

Supramaximal stimulation of the rat pancreas with CCK, or its analog caerulein, triggers acute pancreatitis and a number of pancreatitis-associated acinar cell changes including intracellular activation of digestive enzyme zymogens and acinar cell injury. It is generally believed that some of these various acinar cell responses to supramaximal secretagogue stimulation are interrelated and interdependent. In a recent report, Lu et al. showed that secretin, by causing generation of cAMP and activation of PKA, sensitizes acinar cells to secretagogue-induced zymogen activation, and, as a result, submaximally stimulating concentrations of caerulein can, in the presence of secretin, trigger intracellular zymogen activation. We found that secretin also sensitizes acinar cells to secretagogue-induced cell injury and to subapical F-actin redistribution but that it did not alter the caerulein concentration dependence of other pancreatitis-associated changes such as the induction of a peak plateau intracellular [Ca(2+)] rise, inhibition of secretion, activation of ERK1/2, and activation of NF-kappaB. The finding that secretin sensitizes acinar cells to both intracellular zymogen activation and cell injury is consistent with the concept that these two early events in pancreatitis are closely interrelated and, possibly, interdependent. On the other hand, the finding that, in the presence of secretin, caerulein can trigger subapical F-actin redistribution without inhibiting secretion challenges the concept that disruption of the subapical F-actin web is causally related to high-dose secretagogue-induced inhibition of secretion in pancreatic acinar cells.

Actins↗
PubMed2005

A mouse model of ethanol dependent pancreatic fibrosis.

BACKGROUND AND AIMS: The majority of patients with chronic pancreatitis are alcoholics. Our goal was to develop a mouse model of alcohol dependent chronic pancreatitis. METHODS: Mice were fed either the non-alcohol containing Lieber-DeCarli diet or the Lieber-DeCarli diet containing 24% of calories as ethanol. After eight weeks and while on their respective diets, mice were subjected to repeated episodes of acute pancreatitis elicited by administration of caerulein. They were sacrificed 1, 3, and 5 weeks after the last dose of caerulein. Pancreatic morphology and collagen deposition were evaluated in samples stained with haematoxylin-eosin and Sirius red. Collagen content was quantitated by measuring OH-proline. Gene expression was determined by quantitative polymerase chain reaction. RESULTS: Both groups of mice gained weight at the same rate. Those receiving the alcohol containing diet had serum alcohol levels of approximately 100 mM. No histological or gene expression differences were found in mice that were not subjected to acute pancreatitis, regardless of their diet. Necrosis, Sirius red staining, OH-proline content, and expression of alpha-1 collagen I, alpha-smooth muscle actin, transforming growth factor beta1, and tissue inhibitor of metalloproteinase 1 were all increased in mice fed the alcohol containing diet and given caerulein compared with those fed the control diet and given caerulein. Matrix metalloproteinase 9 expression was transiently decreased in mice fed ethanol and given caerulein compared with the group given caerulein but not fed ethanol. CONCLUSION: We have developed a mouse model of alcohol dependent chronic pancreatic fibrosis. This mouse model may be useful in studies examining the effects of genetic manipulation on chronic pancreatitis.

Animals↗
PubMed2005

Effect of excessive dietary fluoride on nutrient digestibility and retention of iron, copper, zinc, and manganese in growing pigs.

Ninety-six crossbred growing pigs were used to evaluate the effects of fluoride levels on growth performance, nutrient digestibility, and the retention of minerals in tissues. Four dietary treatments were formulated by supplementing fluorine (as NaF) to a corn-soybean basal diet (39.75 mg/kg F) to provide the following added fluorine levels: 0, 50, 100, and 150 mg/kg fluorine. The results showed pigs of the 100 and 150 mg/kg fluorine-added groups had decreased average daily gain (ADG) and increased feed gain ratio (F/G) compared to the control (p < 0.05). Apparent digestibility of protein and calcium in 100 and 150 mg/kg fluorine-treated groups was significantly lower than that of the control (p < 0.05). On the other hand, iron, copper, zinc, and manganese levels in most tissues of the 100 and 150 mg/kg fluorine groups were markedly changed compared to the control (p < 0.05). However, growth performance, nutrient digestibility, and mineral concentrations in all tissues of pigs were not significantly affected by the addition of 50 mg/kg fluorine (p > 0.05). Thus, this study suggested that excess fluoride levels could decrease growth performance and change the retention of iron, copper, zinc, and manganese in pigs.

Animal Nutritional Physiological Phenomena↗
PubMed2004

Triptolide, an active component of the Chinese herbal remedy Tripterygium wilfordii Hook F, inhibits production of nitric oxide by decreasing inducible nitric oxide synthase gene transcription.

OBJECTIVE: The ethyl acetate (EA) extract of Tripterygium wilfordii Hook F (TWHF) and its major active component, triptolide, have been reported to be effective in the treatment of rheumatoid arthritis and other autoimmune inflammatory diseases. Nitric oxide (NO) has been recognized as an important mediator of inflammation. This study was therefore undertaken to examine the effects of the EA extract and triptolide on the production of NO and inducible NO synthase (iNOS) gene expression and transcription in vivo and in vitro. METHODS: Peritoneal macrophages from C57BL/6J mice treated orally with the EA extract of TWHF were assayed for NO production and iNOS messenger RNA (mRNA) expression by reverse transcriptase-polymerase chain reaction. The murine fibroblast cell line NIH3T3 was also assessed for NO production and iNOS mRNA expression, as well as for iNOS promoter activation, Oct-1 nuclear binding capacity, and Oct-1 protein content by transient transfection, electrophoretic mobility shift assay, and immunoblotting, respectively. RESULTS: NO production and iNOS mRNA expression by macrophages from C57BL/6J mice immunized with trinitrophenyl-bovine serum albumin in Freund's complete adjuvant were significantly inhibited by oral administration of the EA extract (52.3% and 59.8% of control, respectively, at one-eighth of the dose that is lethal for 50% of the animals [LD(50)] and 21.0% and 38.1% of control, respectively, at one-fourth the LD(50)). Moreover, the EA extract and triptolide significantly inhibited NO production in vitro in activated peritoneal macrophages, which reflected a decreased level of iNOS mRNA. Finally, triptolide inhibited promoter activity of the iNOS gene and induction of the activity of the regulator of iNOS transcription, Oct-1. CONCLUSION: The EA extract of TWHF and triptolide inhibit transcription of the iNOS gene. This may contribute to the antiinflammatory effects of this traditional herbal remedy.

Animals↗
PubMed2003

Chiral liquid chromatography resolution and stereoselective pharmacokinetic study of the enantiomers of a novel anticonvulsant, N-(4-chlorophenyl)-1-(4-pyridyl)ethylamine, in rats.

A selective chiral high performance liquid chromatographic (HPLC) method was developed and validated to separate and quantify the enantiomers of a novel anticonvulsant agent, N-(4-chlorophenyl)-1-(4-pyridyl)ethylamine (AAP-Cl), in rat plasma. After extraction of the plasma samples with ethyl acetate, the separation was accomplished by an HPLC system consisting of a Chirex chiral column (250 mm x 4.6 mm i.d.) and a mobile phase of hexane:ethanol:tetrahydrofuran (280:20:40 (v/v)) containing trifluroacetic acid (0.3% (v/v)) and triethylamine (0.018% (v/v)) at a flow rate of 0.8 ml/min with UV detection. Male Sprague-Dawley rats were given (+)-AAP-Cl (10 and 20 mg/kg), (-)-AAP-Cl (10 mg/kg) or the racemic mixture (20 mg/kg) by i.v. bolus injection and serial blood samples were collected at different times after drug administration. (+)-AAP-Cl and (-)-AAP-Cl were separated with a resolution factor, Rs, of at least 1.4, and a separation factor, alpha, greater than 1.09. Linear calibration curves were obtained over the concentration range of 0.5-30 microg/ml in plasma for both (+)-AAP-Cl and (-)-AAP-Cl (R2 > or = 0.996) with a limit of quantitation of 100 ng/ml and the recovery was greater than 80% for both enantiomers. The accuracy and precision for both enantiomers ranged from 96 to 102% (+/-0.2-7%) at upper and lower concentrations. The plasma concentration-time profiles of the enantiomers of AAP-Cl were best described by a two-compartment open model with a mean terminal half-life of about 5h, volume of distribution at steady state of 3 l/kg and clearance of about 0.6l/(hkg) in rats. There was no significant difference between the pharmacokinetic parameters of (+)-AAP-Cl and (-)-AAP-Cl, suggesting that the disposition of AAP-Cl in rats is not enantioselective. In addition, no chiral inversion of (+)-AAP-Cl to (-)-AAP-Cl or vice versa was observed. The results of this investigation have shed some light on the mechanism of action and disposition of AAP-Cl in rats.

Animals↗
PubMed2001

Calcium regulation of neuronal gene expression.

Plasticity is a remarkable feature of the brain, allowing neuronal structure and function to accommodate to patterns of electrical activity. One component of these long-term changes is the activity-driven induction of new gene expression, which is required for both the long-lasting long-term potentiation of synaptic transmission associated with learning and memory, and the activity dependent survival events that help to shape and wire the brain during development. We have characterized molecular mechanisms by which neuronal membrane depolarization and subsequent calcium influx into the cytoplasm lead to the induction of new gene transcription. We have identified three points within this cascade of events where the specificity of genes induced by different types of stimuli can be regulated. By using the induction of the gene that encodes brain-derived neurotrophic factor (BDNF) as a model, we have found that the ability of a calcium influx to induce transcription of this gene is regulated by the route of calcium entry into the cell, by the pattern of phosphorylation induced on the transcription factor cAMP-response element (CRE) binding protein (CREB), and by the complement of active transcription factors recruited to the BDNF promoter. These results refine and expand the working model of activity-induced gene induction in the brain, and help to explain how different types of neuronal stimuli can activate distinct transcriptional responses.

Animals↗
PubMed2001

[In vitro inhibitive effects of Tripterygium wilforii on NO production, iNOS activity, and iNOS-mRNA expression in chondrocyrtes of patients with rheumatoid arthritis].

OBJECTIVE: To study the mechanism of treatment of rheumatoid arthritis with Tripterygium wilfordii Hook. f. (TWHF). METHODS: Chondrocytes from the resected knee joint cartilage of patients with rheumatoid and TWHF, dexamethasone, or (arthritis were isolated and cultured. IL-1 indomethacin of different concentrations were added into the culture solution overnight. Griess reagent was added to the supernatant to detect the content of NO. Chondrocytes were collected to examine the iNOS activity by detecting the conversion of L-14C-arginine into L-14C-citruline. The total RNA of chondrocyte was extracted and the iNOS-mRNA was examined by Northern blotting. RESULTS: The inhibitory rates of NO production by TWHF of concentrations of 2 mg/L, 4 mg/L, 8 mg/L, and 16 mg/L were 10.8%, 25.48%, 55.17%, and 80.45% respectively. The inhibitory rates of iNOS activity by TWHF of concentrations of 2 mg/L, 4 mg/L, 8 mg/L, and 16 mg/L were 12.29%, 27.67%, 59.04%, and 85.06% respectively. Such inhibitory effects were dosage-dependent. TWHF ffectively inhibited the expression of iNOS-mRNA induced by IL-1 in chondrocyte (r = 0.976 and 0.974). Dexamethasone inhibited NO production, iNOS activity, and expression of iNOS-mRNA significantly but not dosage-dependently. Indomethcin only had weak inhibitory effect. CONCLUSION: TWHF inhibits NO production in chondrocytes by limiting the transcription of iNOS gene, which may be one of the mechanisms of treatment of RA with TWHF.

Arthritis, Rheumatoid↗
PubMed2001

COMO: a program for combined molecular replacement.

The combined molecular-replacement protocol uses a limited six-dimensional search to solve a structure by the molecular-replacement method, with the sampling of the rotational degrees of freedom guided by the rotation function. This protocol therefore automatically combines the information on the rotational and translational parameters of the search model. The combined molecular-replacement protocol has been implemented in a new computer program, COMO. The calculation of the Patterson correlation translation function has been optimized to improve its speed performance. A packing check is implemented that automatically removes impossible solutions and thereby increases the signal in the calculation. A family of atomic models can be used as the search model; the program will automatically select the model that gives the best result. The command interface is well organized and requires the definition of only a few critical parameters by the user. In addition, a graphical user interface has been constructed for the program. The program has been used to solve several difficult molecular-replacement problems. A case is presented where the program automatically determined the orientation and position of five copies of a search model in a high-symmetry space group.

Computer Simulation↗
PubMed2001

Effect of xiaokuiling prescription on the expression of HSP72, HSP B in gastric mucosa of patients with Helicobacter pylori-associated duodenal ulcer.

In order to investigate the mechanism of Xiaokuiling prescription (XKL) in the treatment of Helicobacter pylori (HP)-associated duodenal ulcer (DU) and the pathophysiologic role of heat shock proteins (HSPs) in the healing of ulcer, the expression of HSP72 and HSP B in gastric mucosa was detected by using SABC immunohistochemistry method and processed by micro-image analysis system. The method of Western blotting was used to measure the contents of HSP72 and HSP B in the tissue emulsion of gastric mucosa. The results were as follows: (1) HSP72 expression of the gastric mucosa in the treated group was obviously increased as compared with that in the control group (P < 0.05); (2) HSP B expression of the gastric mucosa in the treated group was significantly decreased as compared with that in the control group (P < 0.01). It was suggested that the increased expression of HSP72 and the elimination of HP might be related to the mechanism of action of XKL. HSPs might play an pathological and physiological role in the process of healing of gastric ulcer.

Adult↗
PubMed2001

Effect of jianpiyiqi prescription on the expression of heat shock proteins in acetic acid-induced chronic gastric ulcer rats.

To investigate the effect of Jianpiyiqi prescription on the expression of heat shock proteins (HSPs) and the changes of HSPs in gastric-ulcerated rats, the rat model of chronic gastric ulcer was induced by acetic acid. The SABC immunohistochemical method was used to observe HSP70 of mucosa around the gastric ulcer. Imaging analysis was performed. Western dot blot was used to detect HSPs contents in the plasma and gastric mucosal homogenate in each group. The results showed that HSP70 contents of the mucosa around the gastric ulcer in the model group and ranitidine-treated group were increased as compared with control group (P < 0.01). Jianpiyiqi could increase the expression of HSP70 of the mucosa around the gastric ulcer further as compared with that in the model group and ranitidine-treated group (P < 0.01). The HSP70 contents in the serum and mucosa in the model group and ranitidine-treated group were increased as compared with control group (P < 0.01, P < 0.05 respectively). HSP70 of serum and mucosa in the Jianpiyiqi-treated group was higher than in the model group and ranitidine-treated group (P < 0.05, P < 0.01 respectively). It was concluded that HSP might play a role in the process of pathophysiology of gastric ulcer. Jianpiyiqi could enhance gastric ulcer-healing through the protective mechanism of HSPs.

Acetic Acid↗
PubMed2001

Arterial remodeling in chronic sinoaortic-denervated rats.

The spontaneous variation of blood pressure is defined as "blood pressure variability" (BPV). The chronic sinoaortic-denervated (SAD) rat is a model of high BPV without sustained hypertension. Little is known about vascular remodeling in this model. In the present study, we examined blood pressure, vascular remodeling, and aortic angiotensin II concentration in chronic SAD rats in separate experiments. In experiment 1, intra-arterial blood pressure was continuously recorded in conscious unrestrained rats. The 16-week SAD rats had a significant increase in BPV and no change in the mean level of blood pressure over a 24-h period. In experiment 2, we measured structural changes of seven kinds of arteries by histologic method and computer image analysis and functional changes of thoracic aortas by isolated artery preparation. Structural remodeling after 16-week sinoaortic denervation was characterized by increase in wall thickness, wall area, and ratio of wall thickness to internal diameter, with different changes in internal diameter and external diameter in different arteries, indicating that arterial structural remodeling expresses itself mainly as vascular growth. This vascular growth might be caused by medial smooth muscle cell growth and collagen accumulation. Aortic contraction induced by norepinephrine was potentiated, whereas aortic relaxation induced by acetylcholine was attenuated after sinoaortic denervation. In experiment 3, plasma and aortic angiotensin II concentrations were determined by radioimmunoassay. The former remained unchanged, whereas the latter was significantly increased in 10-week SAD rats. It is concluded that in rats chronic sinoaortic denervation can produce vascular remodeling that might be related to increased BPV and an activated tissue renin-angiotensin system.

Angiotensin II↗
PubMed2001

A phase I study of ethyl acetate extract of the chinese antirheumatic herb Tripterygium wilfordii hook F in rheumatoid arthritis.

OBJECTIVE: To explore the efficacy and safety of ethyl acetate (EA) extracts of the Chinese herbal remedy Tripterygium wilfordii Hook F (TWHF) for treatment of patients with a variety of inflammatory and autoimmune diseases including rheumatoid arthritis (RA). METHODS: The roots of TWHF were extracted sequentially by ethyl alcohol and ethyl acetate and the content of the extract documented. An open label, dose escalation Phase I study was performed in 1993 in 13 patients with established RA. Clinical manifestations and laboratory findings were examined before and every 4 weeks after starting treatment with the EA extract. RESULTS: Three patients withdrew from the trial during the first 16 weeks of the dose escalation. These patients received a maximum dosage of 180 mg/day. There were no adverse effects or disease improvement observed in these patients. Nine of the remaining 10 patients tolerated the EA extract up to a dosage of 570 mg/day. There were no withdrawals related to adverse events in the trial except for one patient who developed diastolic hypertension at a dose of 180 mg/day of EA extract. Six of 10 patients treated with 180 mg/day of EA extract showed disease improvement. Eight of the 9 patients who received EA extract at doses > 360 mg/day experienced improvement in both clinical manifestations and laboratory findings. One patient met American College of Rheumatology criteria for remission. CONCLUSION: The EA extract of TWHF at dosages up to 570 mg/day appeared to be safe, and doses > 360 mg/day were associated with clinical benefit in patients with RA.

Acetates↗
PubMed2001

[An epidemic investigation of eperythrozoonsis in Shandong province].

OBJECTIVE: To learn the status of infection of eperythrozoonsis in Shandong province. METHODS: Seven hundred and seventy-six human blood samples, 198 domestic animal blood samples and 114 wild rat blood samples were collected. Eperythrozoon was detected in the human and animal blood stain slides under microscope. RESULTS: Overall infection rate of Eperythrozoon in human population was 7.3%. Rates were significantly different (P < 0.01) in different districts but no significant difference was found between men and women (P > 0.05). The rate among adults was higher than that of teenagers and elderly. It was also noticed that the rates of people affected with chronic diseases as hepatitis, diabetes and arthritis were higher than those without. The infection rates of goat, cows and rats were 15.6%, 3.2% and 0, respectively. CONCLUSION: Data showed that Eperythrozoon infection was intensively identified in the people and animals in Shandong province.

Adolescent↗
PubMed2001

[Analysis on the present situation of human rabies epidemic in China].

OBJECTIVE: To summarize and analyze human rabies epidemic situation in the last five years in China and to explore the possible factors causing the rising of epidemics to provide reference for the prevention and control of rabies in the future. METHODS: Collecting and analyzing data of rabies epidemics in the last five years in whole nation. RESULTS: Human rabies is continuing going up in the last five years in China with an increase of 44.65%, 1.74% and 45.93% in 1997, 1998, 1999. Human rabies incidence was also seen an increase from 0.0134/100,000 in 1996 to 0.02708/100,000 in 1999. The provinces of rabies increase were mainly located in south China. Among them, Jiangsu province reported 40 human cases in 1999, which increased 207.69% than the corresponding period in 1998. The cases in these high epidemic provinces took up 75% of the whole nation's cases. Number of reported rabies case was also rising. CONCLUSION: Facts as increasing number of dog raising, having not been injected with rabies vaccine and antirabies serum timely or full course after exposure, unstrictly controlling the quality of rabies vaccine as well as lacking good cooperation in different official department on rabies control might serve as factors responsible for the recurrent increase of human rabies.

Animals↗