Biomedical subjects

H X Xu

Publications and source records attributed to H X Xu.

At least 19 recordsLinked to original sources

PubMed2006

The comparative study of Sprague-Dawley and Lewis rats in adjuvant-induced arthritis.

The outbred Sprague-Dawley (SD) rats, similar to the inbred Lewis (LEW) rats, have been recently demonstrated to be highly susceptible to adjuvant-induced arthritis (AIA). We herein compared AIA in SD and LEW rats in terms of clinical, histological, radiological, and immuno-inflammatory features. The results showed that, following inoculation with a ground Mycobacterium tuberculosis (MT) suspension, SD and LEW rats manifested closely similar disease progression, with 100% incidence and similar severity. The development of arthritis was accompanied by significantly higher erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels than in control rats. Radiographic examination of the hind paws showed that both SD and LEW AIA rats manifested conspicuous soft tissue swelling, bone matrix resorption, periosteal new bone formation and bone erosion, while histopathological analysis of the synovial joints revealed marked cellular infiltration, angiogenesis, synovial hyperplasia, pannus formation, narrowing of joint space, and cartilage and bone destruction. Moreover, in relation to disease progression, serum tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 levels were markedly overexpressed in both SD and LEW AIA versus control rats, and SD and LEW AIA rats exhibited divergent profiles for the expression of TNF-alpha and IL-1beta. Taken together, these results demonstrated that the SD rat AIA model shares several arthritic features with the comparable model in LEW rats. Hence, given the more favorable characteristics of SD rats than LEW rats (i.e., lower cost, wider availability, and heterogenic background), this SD rat AIA model is more cost effective and advantageous for screening and testing novel anti-arthritic agents.

Animals↗

PubMed2006

Manipulation of the induction of adjuvant arthritis in Sprague-Dawley rats.

OBJECTIVE: To investigate the roles of various variables in the induction of adjuvant-induced arthritis (AIA) in the outbred Sprague-Dawley (SD) rats, and further characterize its arthritic features by comprehensive examinations. METHODS: The roles of different preparative techniques, inoculation routes and doses of Mycobacterium tuberculosis (MT) suspension as well as the sex preference in the induction of AIA were comparatively studied using clinical assessment. The hind paws of animals were analyzed by radiological and histological examinations. The serum levels of cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha were determined by ELISA. RESULTS: The particle size and dose of MT played a dominant role in the induction and severity of AIA. Male rats manifested markedly more severe arthritic signs than female rats. After subcutaneously inoculated with 500 microg MT, male rats developed pronounced arthritis with 100% incidence and low variable clinical signs. Even using only 62.5 microg MT, AIA was efficiently induced in male rats and characterized by upregulated expression profiles of IL-1beta, IL-6 and TNF-alpha. CONCLUSIONS: Since outbred SD rats are much cheaper and more readily available than Lewis rats, this well-developed SD rat AIA model is an efficient and cost-effective arthritis model available for screening novel anti-arthritic agents.

Animals↗

PubMed2006

Pharmacokinetic, tissue distribution, and excretion of puerarin and puerarin-phospholipid complex in rats.

Puerarin is a potential therapeutic agent for cardiovascular diseases. But its poor oral bioavailability restricts its clinical application. In present study, as an evaluation of a formulation to improve the bioavailability of the drug, puerarin and its phospholipid complex were given to rats by intragastrically (i.g.) administration to compare pharmacokinetic, tissue distribution, and excretion. Serum samples were obtained at designated times after a single oral dose of 400 mg/kg puerarin or its complex. Tissue samples (heart, liver, spleen, kidney, lung, and brain), urine, and feces were collected and analyzed by a sensitive and specific high performance liquid chromatography (HPLC) method after i.g. administration of puerarin or its phospholipid complex. Compartmental and non-compartmental analyses were applied to the serum concentration versus time data. Pharmacokinetic parameters were calculated using the 3P97 pharmacokinetic software package. An open two-compartment, first-order model was selected for pharmacokinetic modeling. The results showed that after i.g. administration of 400 mg/kg puerarin and its phospholipid complex (equivalent to 400 mg/kg of puerarin), the pharmacokinetic parameters of the two formulations were different. The serum concentrations reached peaks at 0.894+/-0.521 h and 0.435+/-0.261 h, respectively, indicating the complex was more readily absorbed in serum than puerarin. The maximum concentrations for puerarin and its complex were 1.367+/-0.586 mg.L(-1) and 2.202+/-1.28 mg.L(-1) and AUC were 5.779+/-1.662 mg.h. L(-1) and 8.456+/-0.44 mg.h L(-1), respectively, indicating a higher bioavailability for the complex. The widely distribution characteristics of puerarin and its complex in tissues post-i.g. administration was identical and in a descending order as follows: lung, kidney, liver, heart, spleen, and brain. However, the amount was different. Puerarin distribution was higher in heart, lung, and brain after administering the complex. The cumulative 72 h urinary excretion of puerarin after i.g. administration of puerarin and its complex accounted for 1.05%, 1.11% of the administered dose, respectively. The cumulative feces excretion of puerarin was 32.3% and 25.5%. To sum up, oral administration of puerarin phospholipid complex modified the pharmacokinetics and tissue distribution of puerarin and it could be an effective oral formulation for puerarin.

Administration, Oral↗

PubMed2001

Activity of plant flavonoids against antibiotic-resistant bacteria.

Thirty eight plant-derived flavonoids representing seven different structural groups were tested for activities against antibiotic-resistant bacteria using the disc-diffusion assay and broth dilution assay. Among the flavonoids examined, four flavonols (myricetin, datiscetin, kaempferol and quercetin) and two -flavones (flavone and luteolin) exhibited inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA). Myricetin was also found to inhibit the growth of multidrug-resistant Burkholderia -cepacia, vancomycin-resistant enterococci (VRE) and other medically important organisms such as -Klebsiella pneumoniae and Staphylococcus epidermidis. Myricetin was bactericidal to B. cepacia. The results of the radiolabel incorporation assay showed that myricetin inhibited protein synthesis by -B. cepacia. The structure-activity relationship of these flavonoids is discussed.

Burkholderia↗

PubMed2001

Secoiridoid constituents from the fruits of Ligustrum lucidum.

Two secoiridoid glucosides, lucidumosides A and B, as well as six known glucosides, oleoside dimethyl ester, ligustroside, oleuropein, nuezhenide, isonuezhenide, and neonuezhenide, were isolated from the fruits of Ligustrum lucidum. Their structures were elucidated by spectroscopic methods.

Fruit↗

PubMed2001

In vitro evaluation of secoiridoid glucosides from the fruits of Ligustrum lucidum as antiviral agents.

Six secoiridoid glucosides, lucidumoside C (1), oleoside dimethylester (2), neonuezhenide (3), oleuropein (4), ligustroside (5) and lucidumoside A (6), isolated from the fruits of Ligustrum lucidum (Oleaceae), were examined in vitro for their activities against four strains of pathogenic viruses, namely herpes simplex type I virus (HSV-1), influenza type A virus (Flu A), respiratory syncytial virus (RSV) and parainfluenza type 3 virus (Para 3). Antiviral activities were evaluated by the cytopathic effect (CPE) inhibitory assay. The purpose was to check if the antioxidative potency of these glucosides correlated with their antiviral potency. Results showed that none of the glucosides had any significant activity against HSV-1 and Flu A. Oleuropein, however, showed significant antiviral activities against RSV and Para 3 with IC50 value of 23.4 and 11.7 microg/ml, respectively. Lucidumoside C, oleoside dimethylester and ligustroside showed potent or moderate antiviral activities against Para 3 with IC50 values of 15.6-20.8 microg/ml. These results also documented that the anti-oxidative potency of these secoiriodoid glucosides was not directly related to their antiviral effects.

Animals↗

PubMed2001

Antioxidative glucosides from the fruits of Ligustrum lucidum.

The ethanol extract of the fruits of Ligustrum lucidum was shown to have inhibitory effects on the hemolysis of red blood cells induced by 2,2'-azo-bis-(2-amidinopropane) dihydrochloride. Bioassay-guided analysis led to the isolation of ten secoiridoid glucosides. Two of them were new, lucidumosides C and D. Their structures were elucidated by spectroscopic methods. The other eight compounds were identified as oleoside dimethyl ester, ligustroside, oleuropein, nuezhenide, isonuezhenide, neonuezhenide, lucidumoside A and lucidumoside B. Five compounds, oleoside dimethyl ester, oleuropein, neonuezhenide, lucidumoside B and lucidumoside C, exhibited strong antioxidant effect against hemolysis of red blood cells induced by free radicals.

Antioxidants↗

PubMed2000

Vasorelaxing effects of Caesalpinia sappan involvement of endogenous nitric oxide.

Methanolic extract and two purified compounds (brazilin and hematoxylin) from Caesalpinia sappan were examined for their relaxant effects in isolated rat thoracic aorta. The methanolic extract significantly and dose-dependently relaxed the alpha1-receptor agonist phenylephrine-precontracted aortic rings, without affecting passive tension of these vessels. Removal of the vascular endothelium, inhibition of nitric oxide (NO) synthase with 0.1 mM Nomega-nitro-L-arginine and of cGMP biosynthesis with 10 microM methylene blue abolished the vasorelaxant effects of the herbal extract at doses up to 30 microg/ml. Similar vasorelaxant effects were observed with brazilin and hematoxylin. Therefore, these results suggest that brazilin and hematoxylin may be responsible for the vascular relaxant effects of C. sappan, via endogenous NO and subsequent cGMP formation. The vascular relaxant effects of the plant may contribute to its therapeutic actions.

Animals↗

PubMed2000

[Reconstruction of forearm function by fibular transfer with vascular anastomoses].

OBJECTIVE: To analyse and report the reconstruction of forearm function by fibular transfer with vascular anastomoses. METHODS: Fourteen cases of forearm function dismissed due to defects of bone were managed by fibular transfer with vascular anastomoses. RESULTS: All cases obtained satisfactory effects, and recovered their normal function. CONCLUSION: The vascularized fibular transfer is a good method to reconstruct the forearm function with defects of bone resulting from injury or tumor.

Adolescent↗

PubMed2000

Differentiation and authentication of Panax ginseng, Panax quinquefolius, and ginseng products by using HPLC/MS.

An LC/MS-based method is established for the differentiation and authentication of specimens and commercial samples of Panax ginseng (Oriental ginseng) and Panax quinquefolius (American ginseng). This method is based on the separation of ginsenosides present in the ginseng methanolic extracts using high-performance liquid chromatography (HPLC), followed by detection with electrospray mass spectrometry. Differentiation of ginsenosides is achieved through simultaneous detection of intact ginsenoside molecular ions and the ions of their characteristic thermal degradation products. An important parameter used for differentiating P. ginseng and P. quinquefolius is the presence of ginsenoside Rf and 24-(R)-pseudoginsenoside F11 in the RICs of Oriental and American ginsengs, respectively. It is important to stress that ginsenoside Rf and 24(R)-pseudoginsenoside F11, which possess the same molecular weight and were found to have similar retention times under most LC conditions, can be unambiguously distinguished in the present HPLC/MS method. The method developed is robust, reliable, reproducible, and highly sensitive down to the nanogram level.

Chromatography, High Pressure Liquid↗

PubMed2000

Antioxidant activity of phenylethanoid glycosides from Brandisia hancei.

Brandisia hancei is a medicinal herb in China. The ethanol extract of this plant and four phenylethanoid glycosides, acteoside (1), 2'-acetylacteoside (2), poliumoside (3) and brandioside (4), isolated from it were shown to have inhibitory effects on free radical-induced hemolysis of red blood cells and free radical scavenging activities in vitro. Brandioside (4) and poliumoside (3) showed stronger antioxidant effect than acteoside (1), 2'-acetylacteoside (2) and trolox.

Animals↗

PubMed2000

A rapid method for determining the G+C content of bacterial chromosomes by monitoring fluorescence intensity during DNA denaturation in a capillary tube.

A simple and rapid method to determine the G+C content of bacterial chromosomal DNA was developed. It involves determination of Tm by a Light Cycler and calculation of the G+C content by an empirical formula relating Tm to G+C content. Instead of a conventional thermal denaturation method, which monitors the increase of absorbance at 260 nm, thermal denaturation was monitored by the decrease of fluorescence intensity in the presence of SYBR Green 1. In this method, the apparent Tm of DNA was influenced by the concentration of SYBR Green 1, DNA and salt. In addition, when the G+C content was calculated from a linear equation [(mol% G+Cx = mol% G+Cr+1.99(Tmx-Tmr), where x is the unknown organism and y is the reference organism], an error value was introduced among strains with extremely low or high G+C content. Based upon five standards (G+C contents in the range 33-66 mol%), a suitable equation was formulated for the capillary method: mol% G+Cx = mol% G+Cr+1.4652(Tmx-Tmr)+0.0063(Tmx2-Tmr2). To determine the Tm of organisms within this range of G+C contents, Escherichia coli ATCC 11775T was used as a DNA standard and fixed concentrations of SYBR Green 1, sodium citrate and DNA were used. The data from 37 bacterial strains indicated that this equation behaved well. Because it is rapid and simple, it may prove useful for bacterial identification.

Bacteria↗

PubMed2000

Inhibitory activity of flavonoids and tannins against HIV-1 protease.

Twenty-nine flavonoids and six hydrolyzable tannins were studied for their inhibitory activity against human immunodeficiency virus (HIV)-1 protease using fluorescence and HPLC assays. Among the flavonoids, flavones, flavanones, flavonols, catechols and chalcones, the flavonols were the most active category while flavanones and catechols displayed low activity. Quercetin was the most potent inhibitor of the target enzyme with an IC50 value of 58.8 microM, while butein and luteolin showed moderate activity. Of the hydrolyzable tannins tested, three ellagitannins which contain a hexahydroxvdiphenoyl (HHDP) unit linked to the O-3 and 0-6 positions of the sugar, were found to strongly inhibit HIV-1 protease. The IC50 values of corilagin and repandusinic acid on HIV-1 protease were 20.7 and 12.5 microM, respectively.

Flavonoids↗

PubMed2000

A new cytotoxic polyhydroxysterol from soft coral Sarcophyton trocheliophorum.

A new cytotoxic polyhydroxysterol, 23,24-dimethylcholest-16(17)-E-en-3beta,5alpha,6beta,2 0(S)-tetraol (2), together with nine known compounds was isolated from the soft coral Sarcophyton trocheliophorum. Their structures were determined by spectroscopic methods. Compound 2 showed potent growth inhibitory activity against human HL60 leukemia, M14 skin melanoma, and MCF7 breast carcinoma cells with EC50 values of 2.8, 4.3, and 4.9 microg/ml, respectively, and exhibited minimal toxicity to normal human peripheral blood lymphocytes.

Animals↗

PubMed2000

A new anti-HIV triterpene from Geum japonicum.

Geumonoid (1), a new triterpene, was isolated from Geum japonicum. Its structure was elucidated on the basis of 1D, 2D NMR and MS spectroscopic analysis. Compound 1 showed inhibitory activity against HIV-1 protease.

Anti-HIV Agents↗

PubMed2000

Tripterygium wilfordii saponins and interleukin-10 prevent induction of experimental autoimmune thyroiditis by dendritic cells.

AIM: To study the roles of Tripterygium wilfordii saponins (TII) and interleukin-10 (IL-10) on dendritic cells (DC)-induced experimental autoimmune thyroiditis (EAT). METHODS: We used mice as autoimmune thyroiditis model animals and divided them into 4 groups, namely DC group, TII group, IL-10 group, and control group. The level of thyroglobulin (Tg) antibody was assayed by ELISA. TNF beta production in the cultured supernatants and nitric oxide (NO) in the serum were measured by biological activation assay and Griess reaction, respectively. Tg-stimulated proliferation of lymphocytes was detected with MTT incorporation assay. The histopathological analysis of thyroid was carried out. RESULTS: Tg-pulsed DC were able to induce EAT with increase in the concentration of TgAb in serum and lymphocytes infiltration in thyroid. After treatment with TII or IL-10, DC could not induce EAT with lower levels of TgAb and no lymphocyte infiltration. The concentration of NO in serum, TNF beta activation, and the proliferation of lymphocytes in response to thyroglobulin in TII or IL-10 group were lower than those in DC group. CONCLUSION: TII and IL-10 are able to strongly inhibit the ability of DC to induce experimental autoimmune thyroiditis.

Animals↗

PubMed1999

Determination of quinolizidine alkaloids in traditional Chinese herbal drugs by nonaqueous capillary electrophoresis.

A rapid method for the determination of quinolizidine alkaloids by nonaqueous capillary electrophoresis was developed. A total of 10 alkaloids (matrine, sophocarpine, oxymatrine, oxysophocarpine, sophoridine, cytisine, sophoramine, aloperine, lehmannine and dauricine) could be easily separated within 18 min. A running buffer composed of 50 mM ammonium acetate, 10% tetrahydrofuran and 0.5% acetic acid in methanol was found to be the most suitable for this separation. Five of these alkaloids were selected for further studies. The linear calibration ranges were 2.51-50.1 microg/ml for sophoridine and sophocarpine, 2.71-54.2 microg/ml for matrine, 3.30-65.9 microg/ml for oxymatrine, and 3.10-62.0 microg/ml for oxysophocarpine. The recovery of the five alkaloids was 98.0-101.3% with relative standard deviations from 1.03 to 2.68% (n=5). The limits of detection for all 10 alkaloids were over the range 0.93-2.31 microg/ml. The method was successfully applied to the phytochemical analysis of alkaloid extracts from three commonly used traditional Chinese herbal drugs: Sophora flavescens Ait. (Kushen), S. alopecuroides L. (Kudouzi or Kugancao) and S. tonkinensis Gapnep (Shandougen).

Alkaloids↗

PubMed1999

Antibacterial activities of extracts from Nigerian chewing sticks.

Ten aqueous extracts from wooden chewing sticks widely used in Nigeria for teeth cleaning were studied for antibacterial activities against 25 different bacteria using an agar diffusion assay. The extracts from five sticks, namely Garcinia kola, Anogeissus leiocarpus, Terminalia glaucescens, Sorindeia warneckei and Vitex doniana, exhibited strong activities against a wide spectrum of bacteria including medically and dentally relevant bacteria. Notably, these five chewing stick extracts showed potent activities against methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and multidrug-resistant Burkholderia cepacia and Pseudomonas aeruginosa. Extracts from Vernonia amygdalina, Fagara zanthoxyloides and Massularia acuminata also showed activities against bacteria significant to periodontal disease. Methanol extracts prepared from G. kola, A. leiocarpus and V. doniana were further fractionated by solvent extraction. Results showed that the antibacterial activities were distributed into different fractions suggesting that the sticks contain different active antibacterial principles. In conclusion, the results showed that most of the Nigerian chewing sticks do contain antibacterial activities which may contribute to the reported anticaries effect of chewing sticks. These sticks may be sources for new lead antibacterial agents for therapeutic or preventive applications.

Anti-Bacterial Agents↗