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W Xu

Publications and source records attributed to W Xu.

At least 379 records · Page 21Linked to original sources
PubMed1997

Distribution of immunogenic epitopes on the two major immunodominant proteins (rOmpA and rOmpB) of Rickettsia conorii among the other rickettsiae of the spotted fever group.

Forty-four monoclonal antibodies were raised against strain Seven, the type strain of Rickettsia conorii. Of these 44 monoclonal antibodies, 13, 27, and 4 were demonstrated to be directed against the 116-kDa protein (rOmpA), the 124-kDa protein (rOmpB), and lipopolysaccharide-like antigen, respectively. The antiprotein monoclonal antibodies were found to be directed against 29 distinct epitopes, which were located on the two major immunodominant proteins discussed above. Further analysis showed that strain-specific epitopes were located on the rOmpA protein and species- and subgroup-specific epitopes were located on the rOmpB protein. R. conorii Manuel, Indian tick typhus rickettsia, and Kenya tick typhus rickettsia also possessed all 29 epitopes, whereas the other rickettsiae of the spotted fever group (SFG) expressed between 3 and 25 epitopes, with the exception of Rickettsia helvetica, R. akari, and R. australis which did not possess any epitopes. Additional analyses by Western immunoblotting confirmed that the epitopes shared among the SFG rickettsiae were located on the same two high-molecular-mass proteins as on R. conorii. However, although epitopes on the R. conorii rOmpB protein were expressed on the rOmpB proteins of most other SFG rickettsiae, some were found on the rOmpA proteins of R. aeschlimannii, R. rickettsii, and R. rhipicephali. Both proteins possessing the common epitopes were found to have different sizes in the SFG rickettsial species. The different distributions of common epitopes in the SFG rickettsiae were also used to build a taxonomic dendrogram, which demonstrated that all the R. conorii strains formed a relatively independent cluster within the SFG rickettsiae and was generally consistent with previously proposed taxonomies.

Antibodies, Monoclonal↗
PubMed1997

Characterization of and application of monoclonal antibodies against Rickettsia africae, a newly recognized species of spotted fever group rickettsia.

Rickettsia africae is a newly described species which causes African tick bite fever. Mediterranean spotted fever caused by R. conorii is endemic in the same regions of Africa as tick bite fever, and differentiation of the two syndromes by characterization of their etiological agents is important for epidemiological studies. R. africae and R. conorii are, however, difficult to distinguish, and therefore, our aim was to produce monoclonal antibodies to address this problem. Monoclonal antibodies were produced against R. africae by fusing splenocytes from BALB/C mice immunized with purified rickettsial organisms and SP2/0-Ag14 myeloma cells. A total of 355 hybridomas producing monoclonal antibodies to R. africae were identified by initial screening with six different antigens by microimmunofluorescence assay. A panel of 23 representative monoclonal antibodies were selected and subcloned. This panel was screened with a further 17 different spotted fever group (SFG) rickettsial reference antigens. Of these 23 monoclonal antibodies, 1 cross-reacted with only R. parkeri, whereas the others cross-reacted with more than two different antigens. Immunoblotting indicated that all the monoclonal antibodies were directed against the epitopes on two major high-molecular-mass heat-labile proteins, of which the molecular masses were 128 and 135 kDa, respectively. This monoclonal antibody panel was used successfully to identify R. africae in the blood culture of an infected patient, in infected cells within shell vials, and in infected ticks collected from Africa. Furthermore, the cross-reactivity of each SFG rickettsia with each of these 23 monoclonal antibodies was scored and was used to build a dendrogram of taxonomic relatedness between R. africae and the other SFG rickettsiae on the basis of Jaccard coefficients and unweighted pair group method with arithmetic mean analysis. The relatedness was generally consistent with that obtained by other methods of comparison.

Africa↗
PubMed1997

Production of monoclonal antibodies against Rickettsia massiliae and their use in antigenic and epidemiological studies.

Rickettsiae are gram-negative, obligate intracellular bacteria which have historically been divided into three groups: the typhus group, the scrub typhus group, and the spotted fever group (SFG). Recently, several new SFG rickettsiae have been characterized, and most of these species are associated with ticks and have, as yet, no known pathogenicity toward humans. Rickettsia massiliae, which is widely distributed in Europe and Africa, is one such rickettsia. In order to investigate the antigenic relationships between R. massiliae and other rickettsial species and to develop a more convenient methodology for identifying R. massiliae, we produced monoclonal antibodies against the type strain (Mtu1T) of R. massiliae by fusing immunized splenocytes with SP2/0-Ag14 myeloma cells. A panel of 16 representatives were selected from the 163 positive hybridomas identified on initial screening, and their secreted monoclonal antibodies were further characterized. The reactivities of these 16 monoclonal antibodies with a large panel of rickettsial species were assessed by the microimmunofluorescence assay. All species of the SFG rickettsiae reacted with the monoclonal antibodies directed against epitopes on lipopolysaccharide, which is the common antigen among the SFG rickettsiae. Some closely related species of the SFG, such as Bar29, "R. aeschlimanni," and R. rhipicephali, showed strong cross-reactivities with the monoclonal antibodies directed against epitopes on the two major high-molecular-mass heat-labile proteins (106 and 120 kDa). In addition, species-specific monoclonal antibodies demonstrated that R. massiliae is antigenically different from other rickettsial species. Moreover, these species-specific monoclonal antibodies were successfully used for identifying R. massiliae in the ticks collected from southern France, and are therefore potentially useful tools in the identification and investigation of R. massiliae in ticks in large-scale field work.

Antibodies, Bacterial↗
PubMed1997

Rat osteoblast and osteosarcoma nuclear matrix proteins bind with sequence specificity to the rat type I collagen promoter.

The nuclear matrix mediates the 3-dimensional organization of DNA and supports DNA replication and its transcription. We hypothesize that the osteoblast nuclear matrix contributes to the transcriptional control of type I collagen (COL1A1) expression. Cis-regulatory elements of the rat COL1A1 promoter that control osteoblast expression in vivo are between -2.3 and -1.67 kilobase pairs (kb) but lie within -3.5 and -2.3 kb in cultured bone cells. This may result from differences in cell architecture between osteoblasts in tissue and those in vitro. Our aim was to identify osteoblast nuclear matrix proteins (NMPs) that associated with sequence-specificity to the COL1A1 promoter. We used osteoblasts from the rat metaphyseal femur and the rat osteosarcoma cells, ROS 17/2.8. Nuclear matrix and soluble nuclear proteins were obtained as separate subfractions. Gel mobility shift analysis, using fragments of the COL1A1 promoter, was used to identify DNA-binding proteins in the nuclear subfractions. A NMP-DNA interaction, NMP3, was observed between -2149 and -2106 nucleotide in both osteoblasts and osteosarcoma cells. NMP4 was detected between -3518 to -3406 nucleotide. Therefore, osteoblast NMPs recognize sequences in regulatory regions of the COL1A1 promoter and may link cell structure and the transcriptional regulation of this protein.

Animals↗
PubMed1997

[Pleural amyloidosis].

OBJECTIVE: To evaluate the clinical significance of systemic amyloidosis in the differential diagnosis of pleural effusion. METHOD: Retrospective analysis of the incidence and the characteristics of pleural effusion in systemic amyloidosis. RESULTS: Seven (47%) of 15 cases of systemic amyloidosis were complicated with pleural effusion, of them 4 cases were confirmed by positive Congo red stain of percutaneous pleural biopsies specimens. CONCLUSIONS: Systemic amyloidosis involving pleura was not rare. Pleural amyloidosis should be suspected in pleural effusion complicated by multiorgan disease. Percutaneous pleural biopsy with Congo red stain can confirm the diagnosis.

Adult↗
PubMed1997

[The changes and clinical significance of serum CRP, C3, Tf, and PA in the early postburn stage].

The aim of this study was to investigate the regulation and clinical significance of serum acute phase proteins. The patients were divided into three groups: group I consisted of 11 patients with less than 20% of TBSA; group II 10 patients with 20-50% of TBSA and group III 11 patients with more than 50% of TBSA. Blood samples were taken at 8, 24, 48 and 72 h postburn, and in group III additional blood samples were taken on the 7th, 14th, 21st day or in septic episode. The concentration of CRP and C3, Tf, PA were detected by rate nephelometry, agar immunodiffusion and rocket immunoelectrophoresis respectively. Compared with controls, the peak value of CRP was observed during 48-72 h (P < 0.01), C3 decreased at 8 h and lowest at 24 h. Tf was lowered at 48 h, PA and Tf shared the similar changes. However, all four variables had no marked difference during infection and sepsis. The results showed no correlation between C3 and CRP (r = 0.0885, P > 0.05). The results suggested that: 1. CRP mainly reflected the extent of injury but not sepsis; 2. increased CRP was not the causative factor of decreased C3. Tf reduction accelerated bacterial growth.

Adult↗
PubMed1997

[Study on the effect of ofloxacin and tanshinone II A on human leukocyte chemotactic migration in vitro].

In order to verify the possible anti-inflammatory activity and their potency of ofloxacin and Tanshinone II a, the effects of different concentrations of ofloxacin, Tanshinone II a and hydrocortisone on human leukocyte migration in vitro were investigated employing agarose migration technique in which f-Met-Lea-Phe was served as chemotactic factor. The results showed that all the three agents could inhibit migration of leukocytes remarkably. The effects were concentration-dependent with excellent linear relationship. The IC50 were: Tanshinone II a 0.46 microgram/ml, ofloxacin 0.63 microgram/ml, and hydrocortisone 46.52 micrograms/ml respectively. The results indicated that Tanshinone II a was the most potent agent for inhibiting migration of human leukocytes in vitro and the hydrocortisone was relatively less potent.

Abietanes↗
PubMed1997

[Clinical significance of multidrug resistance gene(mdr1) expression in patients with acute leukemia].

OBJECTIVE: To evaluate relationship between drug resistance of leukemia cells and prognosis. METHODS: The expression of multidrug resistance gene(mdr1) mRNA was measured in 85 patients with acute leukemia and in 20 normal controls by using reverse transcription polymerase chain reaction (RT-PCR). RESULTS: The mdr1 positive rate in untreated group was 44.7%. The CR rate differed significantly between mdr1+ (23.9%) and mdr1-(88.5%)(P < 0.005). The mdr1 positive rate of refractory-relapsed group was higher than that in CR group (P < 0.001). The mdr1 mRNA expression level of refractory-relapsed group was higher than that in CR group. A gradually increasing level of mdr1 mRNA expression in CR patients indicated early relapse. The mdr1 positive rate in normal contral and long-term surviver patients was very low. The mdr1 expression was correlated with French-American-Birtish Cooperative Group (FAB) classification. CONCLUSION: The mdr1 expression correlated with chemotherapeutic effect and prognosis. It is an unfavorable prognostic factor for patients with acute leukemia.

Adolescent↗
PubMed1997

[Chemical studies on Campylotropis hirtella (Franch. Schindl.)].

From the roots of Campylotropis hirtella 6 compounds were isolated. Based on the extensive spectrae analysis their chemical structures were identified as beta-sitosterol, oleanolic acid, ursolic acid, euscaphic acid, tomentic acid and rosamultin.

Drugs, Chinese Herbal↗
PubMed1997

[The research on analgestic and anti-inflammatory action of different processed products of Achyranthes bidentata].

Analgestic effect of different processed products of Achyranthes bidentata in mice was observed in hot plate and acetic acid induced writhing test. The experiment results showed that water extract of Achyranthes bidentata and its processed products could inhibit the pain. The analgestic effect of its product processed with wine is the most powerful and lasting. The results showed that Achyranthes bidentata could obviously inhibit the ear inflammation of mice which was led by croton fruit oil. The anti-inflammatory effect of its product processed with wine is the most powerful.

Acetic Acid↗
PubMed1997

[Reversed-phase high performance liquid chromatographic determination of propofol in human plasma].

An RP-HPLC method is described for the assay of propofol (2,6-diisopropylphenol), a new anesthesia drug, in human plasma. Protein in sample was precipitated with methanol, followed by extraction of propofol with cyclohexane. Both propofol and the internal standard thymol were derivatized with Gibbs' reagent and then chromatographed on an ODS column (Ultrasphere, 250 mm x 4.6 mm i.d.) with a mobile phase of acetonitrile-water-trifluoroacetic acid (80:20:0.1) and UV detection at 276 nm. The detectable limit of propofol was 24.8 microg/L (S/N>2) and calibration curves were linear between 50 to 1500 microg/L (r=0.9991). The average coefficient of variation was 6.1%.

Chromatography, High Pressure Liquid↗
PubMed1997

Heterozygous P0 knockout mice develop a peripheral neuropathy that resembles chronic inflammatory demyelinating polyneuropathy (CIDP).

Demyelinating peripheral neuropathies are clinically divided into inherited and acquired types. Inherited demyelinating neuropathies are caused by mutations in genes expressed by myelinating Schwann cells, whereas acquired ones, including chronic inflammatory demyelinating polyneuropathy (CIDP), are probably caused by autoimmune mechanisms. We find that heterozygous P0 knockout (P0+/-) mice develop a neuropathy that resembles CIDP. By one year of age, P0+/- mice develop severe, asymmetric slowing of motor nerves, with temporal dispersion or conduction block, which are features of acquired demyelinating neuropathies including CIDP. Moreover, morphological analysis of affected nerves reveals severe and selective demyelination of motor fibers, focal regions of demyelination, and inflammatory cells. These data suggest that immune-mediated mechanisms may contribute to the pathogenesis of the neuropathy in P0+/- mice.

Action Potentials↗
PubMed1997

[Tumor necrosis factor in pregnancies associated with pregnancy induced hypertension].

OBJECTIVE: To determine TNF concentrations in maternal plasma, amniotic fluid and umbilical blood of normal term pregnant women and women with pregnancy induced hypertension (PIH). METHODS: Sixteen normal term-pregnant women as control and fourty-six women with PIH were enrolled for study. Maternal plasma including antepartum and 72 hours after labor, amniotic fluid and umbilical blood TNF concentrations were measured with a sensitive radioimmunoassay. RESULTS: Similar levels of TNF were found in the amniotic fluid and umbilical blood between the two groups. Before labor, maternal plasma TNF level in PIH was generally higher than that in the control, especially a higher level in the moderate and severe PIH (P < 0.05). However, the mean levels of plasma TNF were not significantly different between the two groups after labor. TNF levels in amniotic fluid were significantly lower than those in maternal plasma and umbilical blood. Amniotic fluid and umbilical blood TNF levels in PIH with intrauterine growth retardation (IUGR) were significantly higher than those in PIH without IUGR (P < 0.05). CONCLUSION: Our study demonstrated an increase of TNF level in maternal plasma with PIH. The results may show an abnormal maternal immune reaction to the fetus. An abnormal higher TNF level may have an effect on the pathogenesis of PIH.

Amniotic Fluid↗
PubMed1997

[The monitoring of post cesarean section uterine scal with B-ultrasonographic and clinical detections].

OBJECTIVE: To find out an effective method for monitoring the healing of uterine incision after cesarean section. METHODS: 1,145 patients with cesarean section were monitored by B-ultrasonography. In 19 patients who revealed fluid mass in uterine incision, 10 cases were treated by percutaneous drainage under sonographic guidance and 9 cases as control. RESULTS: According to sonographic characteristics, uterine incision healing can be divided into three conditions: normal type revealing a smooth strong echo's light band in uterine incision (93.97%), inflammatory type revealing an uneven parenchymatous light mass (3.67%), and fluid mass with inflammation revealing a complex light mass with low echo's or anechoic area (2.36%). There were abnormal clinical signs in most cases of inflammation. The percutaneous drainage therapy showed marked effect. CONCLUSIONS: The monitoring of uterine incision healing by B-ultrasonography plays an important role in preventing late post-partum hemorrhage.

Cesarean Section↗
PubMed1997

[Colour Doppler ultrasonographic indices in predicting fetal hypoxia and acidosis].

OBJECTIVE: To evaluate the effect of uterine-placental-fetal blood flow velocity waveforms (FVWs) on predicting fetal hypoxia and acidosis in high risk pregnancy. METHODS: 46 women of normal term pregnancy (normal group) and 32 women of high risk term pregnancy (high risk group) were examined with colour Doppler ultrasound for their FVWs including maternal uterine artery (UtA), fetal umbilical artery (UmA), middle cerebral artery (MCA), and renal artery (RA). Umbilical artery blood gases were analysed at delivery in high risk group. RESULTS: The resistance index (RI), pulsatile index (PI) and ratio of peak systolic to least diastolic flow velocity (S/D) of UtA, UmA and RA were higher and the PI, S/D of MCA was lower significantly in the high risk group than that of normal the group (P < 0.05). In the high risk pregnancy, when UmA PO2 was less than 2.5 kPa, the S/D of UtA, PI, S/D of UmA and RI, PI, S/D of RA were increased, and the PI of MCA was decreased (P < 0.05). There were a positive correlation between PI of UmA, RA and PO2 pH of UmA, and a negative correlation between the former and PCO2 of UmA. But there were a negative correlation between PI of MCA and PO2, pH of UmA, and a positive correlation between the former and UmA PCO2. CONCLUSION: In the high risk pregnancy, fetal cerebral blood flow increased, whereas blood flow of fetal peripheral vessels (especially renal vessel) decreases. There is a good correlation between fetal hypoxia and fetal blood FVWs. The indices of the fetal blood FVMs can identify fetal hypoxia and acidosis.

Acidosis↗