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Biomedical subjects

B Xiao

Publications and source records attributed to B Xiao.

At least 37 records · Page 2Linked to original sources
PubMed2001

Emergency contraception with Multiload Cu-375 SL IUD: a multicenter clinical trial.

The objectives of the present study were to evaluate the efficacy and side effects and the benefits and limitations of inserting Multiload intrauterine device (IUD) for emergency contraception. A total of 1013 women requesting emergency contraception was recruited, among whom 843 were parous women and 170 nulliparous women. Multiload Cu-375 SL IUD was inserted within 120 h after unprotected intercourse. A urine test for pregnancy was performed before IUD insertion to rule out pregnancy. Participants were followed-up until 1 week after the expected day of the next menstruation. Pregnancy test or ultrasound scanning were performed if menstruation did not return. Efficacy of preventing unplanned pregnancy was calculated. Efficacy and side effects were compared between the parous and nulliparous groups. The results showed that there were two pregnancies, one in each group. The pregnancy rate was 0.2 per 100 women. The efficacy rate of preventing unwanted pregnancy in the parous group was 98.1% and in the nulliparous group 92.4%. The difference was not significant. Removal of IUD because of pain and bleeding was 2.5% in parous women, but was more in the nulliparous group (10.6%). After the return of menstruation, 95.7% of parous women and 80% of nulliparous women maintained the IUD for contraception. There were two complete expulsions and three partial expulsions of the IUD, but there was no significant changes in menstruation and bleeding pattern, nor was infection or trauma observed. It was concluded that IUD insertion is a safe and effective method for emergency contraception for both parous and nulliparous women. One of the advantages of using an IUD is its long-term contraceptive effect, if the women prefer to continue its use.

Contraceptives, Postcoital↗
PubMed2001

Structure and dynamics of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase.

Folates are essential for life. Unlike mammals, most microorganisms must synthesize folates de novo. 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in folate pathway, and therefore, is an ideal target for developing novel antimicrobial agents. Because of its small size and high thermal stability, E. coli HPPK is also an excellent model enzyme for studying the mechanisms of enzymatic pyrophosphoryl transfer. We have determined the crystal structures of HPPK in the unligated form and in complex with HP, two Mg2+ ions, and AMPCPP (an ATP analog that inhibits the enzymatic reaction). Comparison of the two crystal structures reveals dramatic conformational changes of three flexible loops and many side chains and possible roles of the active site residues.

Adenosine Triphosphate↗
PubMed2001

Construction and selection of the natural immune Fab antibody phage display library from patients with colorectal cancer.

AIM: To construct the natural immune Fab antibody phage display libraries of colorectal cancer and to select antibodies related with colorectal cancer. METHODS: Extract total RNA from tissue of local cancer metastasis lymph nodes of patients with colorectal cancer. RT-PCR was used to amplify the heavy chain Fd and light chain kappa and the amplification products were inserted successively into the vector pComb3 to construct the human libraries of Fab antibodies. They were then panned by phage display technology. By means of Dot immunoblotting and ELISA, the libraries were identified and the Fab phage antibodies binding with antigens of colorectal cancer were selected. RESULTS: The amplified fragments of Fd and kappa gained by RT-PCR were about 650 bp. Fd and kappa PCR products were subsequently inserted into the vector pComb3, resulting in a recombination rate of 40% and the volume of Fab phage display library reached 1.48 x 10(6). The libraries were enriched about 120-fold by 3 cycles of adsorption-elution-multiplication (panning). Dot immunoblotting showed Fab expressions on the phage libraries and ELISA showed 5 clones of Fab phage antibodies which had binding activities with antigens of colorectal cancer. CONCLUSION: The natural immune Fab antibody phage display libraries of colorectal cancer were constructed. They could be used to select the relative antibodies of colorectal cancer.

Antibodies↗
PubMed2001

[A study of survival motor neuron and neuronal apoptosis inhibitory protein gene in spinal muscular atrophy].

OBJECTIVE: To study the absence of survival motor neuron(SMN) gene exon 7,8 and neuronal apoptosis inhibitory protein(NAIP) gene exon 5,6 in Chinese patients with type I - IV spinal muscular atrophy (SMA) and to confirm the relationship between the deletions of SMN, NAIP and SMA phenotype. METHODS: PCR and PCR-enzyme methods were used to detect the deletions of NAIP gene exon 5,6 and SMN gene exon 7,8 in 45 SMA (I - IV) patients and 30 healthy relatives of the patients and 30 normal controls. RESULTS: Deletions of exon 7 and 8 of the telomeric SMN gene were 4/4, 2/3, 1/8 and 0/30 in type I, II, III and IV SMA patients, respectively. One patient with type II lacked the exon 7 but retained exon 8. No deletions was found in the relatives and controls(0/60). No deletions of exon 5 and 6 of the NAIP gene was detected in all the patients, healthy relatives and controls. CONCLUSIONS: Deletions of SMN gene exon 7 and 8 exa mined by PCR-enzyme digestion could be recommended as an accurate gene diagnostic method for SMA with type I and II. However, the method was not as useful in type III as in I and II for making a diagnosis of SMA. Type IV SMA, a heterogeneous disease with phenotypical similarities to type I - III SMA, may be caused by deletion of other genes. The frequency of NAIP deletion was lower in Chinese SMA patients.

Child↗
PubMed2001

[The effect of alcohol on c-fos gene expression in rat embryo neuroglial].

OBJECTIVE: This paper is aimed to explore the mechanisms of brain development abnormality induced by alcohol. METHODS: Astrocytes and oligodendrocytes of 19-day rat embryo were exploited and cultured in vitro, and alcohol and its metabolite product (acetaldehyde) were added to DMEMF(12) medium. After different exposure times, c-fos expression of astrocytes and oligodendrocytes was measured by the immunocytochemistry technique. RESULTS: Changes in c-fos gene expression induced by alcohol and acetaldehyde was time and dose dependent. After 1 hr exposure, alcohol and acetaldehyde affected c-fos gene expression in two kinds of neuralglia. C-fos positive expression reached peak value after 2 hr, but recovered after 72 hr and showed special time phase expression. CONCLUSIONS: Alcohol and acetaldehyde cause abnormal increase of c-fos gene expression in astrocytes and oligodendrocytes. This abnormal expression may play an important role in abnormal brain development induced by alcohol.

Acetaldehyde↗
PubMed2001

[Studies on liver cancer induced by non-necrotizing dose of diethylnitrosamine in rats].

OBJECTIVE: To provide an appropriate animal model of liver cancer and sensitive indicator for carcinogen risk assessment. METHODS: The developmental processes of liver cancers in rats initiated by non-necrotizing dose of diethylnitrosamine and promoted by phenobarbital were studied. RESULTS: Most of the preneoplastic lesions and liver cancers were made up of eosinophilic cells. The placental glutathione S-transferase (P-GST) staining could allow a lot of positive single cells, foci and nodules to be seen. But the lesions showed by HE staining expressed higher proliferating cell nuclear antigen (PCNA) than those showed by P-GST staining expressed, indicating a greater possibility for these lesions to persist and develop further. The cellular morphologic analysis demonstrated that the ratio of nuclear radii to cytoplasm radii decreased in the cell in PCNA positive expressing nodules. In addition, the nodules showed by P-GST expressed higher PCNA than those the foci expressed, indicating an increased possibility to develop further in the nodules. CONCLUSION: PCNA expression may be used as a relatively ideal marker for predicting the potential development of precancerous lesions in the experimental model of rat liver cancer induction.

Animals↗
PubMed2001

[An experimental study of effects of injection of pingyangmycin on activities of enzyme of endothelial cells].

OBJECTIVE: The objective of this study is to investigate the mechanism of acute trauma of endothelium after injection of Pingyangmycin. METHODS: A total of 42 adult Wistar rats were divided randomly into experimental groups (24), positive control groups (12) and normal control group (6), and the rats in the experimental or the positive control groups were injected with Pingyangmycin or sodium morrhuate into the mesenteric veins respectively, and then the enzyme activity of hepatic endothelial cells and hepatocytes was examined histochemically 0.5, 1, 2, 4, 8 and 24 hours after injection. RESULTS: After injection, the activity of 5'-nucleinase(5'-N) in hepatic endothelial cells and that of lactic dehydrogenase (LDH) and succinodehydrogenase (SDH) in hepatocytes decreased gradually, but that injected Pingyangmycin was less than that injected sodium morrhuate. CONCLUSION: The trauma caused by Pingyangmycin is less than that caused by sodium morrhuate, but the reaction of trauma caused by both is nonspecific.

5'-Nucleotidase↗
PubMed2001

[Bcl-2, p53 expression and Epstein-Barr virus infection in primary nasopharyngeal carcinoma].

OBJECTIVE: To observe bcl-2, p53 gene expression and Epstein-Barr virus (EBV) infection and their relationship with clinicopathologic factors in primary nasopharyngeal carcinoma (NPC). METHOD: p53, bcl-2 proteins were assayed with immunohistochemical technique and EBV were assayed with polymerase chain reaction in 54 cases of NPC and 13 cases of chronic inflammation of nasopharyngeal epithelium (CINE). RESULT: The expression of p53, bcl-2 proteins and EBV were found respectively in 1(7.7%), 3(23.1%) and 1(7.7%) of 13 CINEs, which were significantly lower than those in 54 NPCs with respectively 41(75.9%), 48(88.9%) and 47(87%) (P < 0.01). In 39 cases of 54(72.2%) NPCs, we could find simultaneous p53, bcl-2 expression and EBV infection, furthermore, p53 and bcl-2 expression were significantly positively correlated with each other (r = 0.78, P < 0.01). p53 gene expression was significantly correlated with cervical lymph node metastasis of NPCs (P < 0.01). The expression of p53 in stage II, III, IV (92.9%, 78.9% and 100% respectively) were significantly higher than that in stage I (38.5%) (P < 0.01). CONCLUSION: The expression of p53, bcl-2 gene and EBV infection are the useful factors in the diagnosis of NPC, the overexpression of p53 is related with the stage and cervical lymph node metastasis of NPC, all the three play important roles in the pathogenesis of nasopharyngeal carcinoma.

Adolescent↗
PubMed2001

[Histopathological observation of acute facial nerve impairment in rabbits].

OBJECTIVE: To investigate histopathological changes of acute facial nerve impairment. METHODS: Ligation of facial nerve outside stylomastoid foramen with 3-0 silk, observation of histopathological changes of facial nerve on the 1st day, 3rd day and 5th day after ligation. RESULTS: The facial nerve showed all kinds and various degrees of histopathological changes, from swelling to degeneration, in myeline and axon respectively. CONCLUSION: All kinds and various degrees of pathological changes have been observed in myeline and axon after the ligation of facial nerve in rabbits. This study demonstrates that such injuries to the facial nerve become increasingly serious as the ligation lasts day after day.

Animals↗
PubMed2001

[A clinical evaluation on reconstruction in extended partial laryngectomy for transglottic cancer].

OBJECTIVE: Transglottic cancer has been a definite indication for total laryngectomy in decades, compromising function of the larynx. The purpose of this study is to present a new radical surgery of extended partial laryngectomy and reconstruction to restore the essential function of larynx. METHODS: Forty-one cases of transglottic cancer were treated by extended vertical laryngectomy (26/41), extended frontolateral laryngectomy (5/41) and subtotal laryngectomy (10/41); the defects of larynx were reconstructed by rotary door myocutaneous flap in twenty-seven cases, by sternohyoideus flap in seven cases, by osteomuscular flap in five cases and by sternocleidomastoid flap in two cases. RESULTS: The 3 and 5 year survival rates were 85.7% (30/35) and 74.1% (20/27) respectively, those for stage III were 84.6% (22/26) and 76.2% (16/21), for stage IV were 3/4 and 1/2 respectively. All cases resumed acceptable voice, 92.7% (38/41) and enjoyed satisfactory phonation. The over-all decannulation rate was 87.8% (36/41), those with rotary door myocutaneous flap was 96.3% (26/27), with sternohyoideus flap was 5/7, with osteomuscular flap was 4/5 and with sternocleidomastoid flap was 1/2. All patients had normal swallow function. CONCLUSION: Extended partial laryngectomy is a kind of radical operation in selected cases of transglottic cancer. The method of reconstruction with rotary door myocutaneous flap can improve curative effect and the essential functions of the larynx.

Adult↗
PubMed2001

[The experimental study of intratemporal facial nerve regeneration in chitin chamber].

OBJECTIVE: To investigate the feasibility of intratemporal facial nerve regeneration in a chitin chamber. METHODS: A left 6 mm intratemporal facial nerve gap was created in adult white rabbit, and a total of 48 animals were used. The proximal and distal stumps were bridged with chitin chamber (experimental group) and silicone chamber (control group). Regeneration of the nerve was assessed by gross observation, nerve electrophysiological test, histological examination and digital morphological analysis in both groups. RESULTS: 1. Three months after implantation, the proximal transected neural stump was connected with the distal stump in the chitin chamber. Five months after operation, the regenerated nerve exhibited a more nature fascicular organization and the chitin tubes were completely absorbed. 2. Nerve evoked potentials showed better conduction ability in the chitin chamber. There were no significant difference in electrophysiological indices between the two chamber groups. 3. Most of the regenerated nerve fibers were myelinated nerve fibers, and axons and myelins had similar histograms between the experimental and control groups. 4. Five months after operation, the mean percentage of recovery of the regenerated nerve fiber area, axonal area and axonal number were more than 71% in the experimental group. There was no significant difference between the control and experimental groups. CONCLUSION: These results suggested that intratemporal facial nerve could regenerate effectively within the chitin chamber in rabbits and such kind of chamber may be clinically useful.

Animals↗
PubMed2001

[Differences of anatomic variations in ostiomeatal complex between two sides of the deviated septum].

OBJECTIVE: To explore the influence of the deviated septum on the development of ostiomeatal complex (OMC). METHODS: Nasal endoscopic examination and CT scan of the paranasal sinuses of 103 patients with nasal septal deviation were analyzed. The differences of anatomic variations in OMC between ipsilateral and contralateral sides in relation to the direction of septal deviation. The incidence of sinusitis on either side of the deviated septum was evaluated. RESULTS: On the side opposite to the deviated septum, the incidence of middle and inferior turbinate hypertrophy was higher than that of the deviated side(P < 0.05). The width of agger nasi and ethmoid bulla was on the contralateral side larger than that of the ipsilateral side (P < 0.01). The incidence of paradoxical curvature of middle turbinate on the ipsilateral side was higher than that of contralateral side (P < 0.01). Other anatomic variations showed no significant differences between two sides of the deviated septum (P > 0.05), nor was there any difference between the incidence of sinusitis on the two sides. CONCLUSION: Some compensatory changes in middle and inferior turbinates and lateral nasal-wall on the opposite side to the deviation might be caused by the deviated septum.

Adolescent↗
PubMed2000

Dendritic and axonal targeting of type 5 metabotropic glutamate receptor is regulated by homer1 proteins and neuronal excitation.

The physiological actions of neurotransmitter receptors are intimately linked to their proper neuronal compartment localization. Here we studied the effect of the metabotropic glutamate receptor (mGluR)-interacting proteins, Homer1a, b, and c, in the targeting of mGluR5 in neurons. We found that mGluR5 was exclusively localized in cell bodies when transfected alone in cultured cerebellar granule cells. In contrast, mGluR5 was found also in dendrites when coexpressed with Homer1b or Homer1c, and in both dendrites and axons when cotransfected with Homer1a. In dendrites, cotransfected mGluR5 and Homer1b/c formed clusters that colocalized with the synaptic marker synaptophysin. Interestingly when transfected alone, the Homer proteins were also translocated to neurites but did not form such clusters. Depolarization of the neurons with a mixture of ionotropic glutamate receptor agonists, NMDA and kainate, or potassium channel blockers, tetraethylammonium and 4-aminopyridine, induced transient expression of endogenous Homer1a and persistent neuritic localization of transfected mGluR5 even long after degradation of Homer1a. These results suggest that Homer1a/b/c proteins are involved in the targeting of mGluR5 to dendritic synaptic sites and/or axons and that this effect can be regulated by neuronal activity. Because the activity-dependent effect of endogenous Homer1a was also long-lasting, the axonal targeting of mGluR5 by this protein is likely to play an important role in synaptic plasticity.

Animals↗
PubMed2000

Homer proteins regulate coupling of group I metabotropic glutamate receptors to N-type calcium and M-type potassium channels.

Group I metabotropic glutamate receptors (mGluR1 and 5) couple to intracellular calcium pools by a family of proteins, termed Homer, that cross-link the receptor to inositol trisphosphate receptors. mGluRs also couple to membrane ion channels via G-proteins. The role of Homer proteins in channel modulation was investigated by expressing mGluRs and various forms of Homer in rat superior cervical ganglion (SCG) sympathetic neurons by intranuclear cDNA injection. Expression of cross-linking-capable forms of Homer (Homer 1b, 1c, 2, and 3, termed long forms) occluded group I mGluR-mediated N-type calcium and M-type potassium current modulation. This effect was specific for group I mGluRs. mGluR2 (group II)-mediated inhibition of N-channels was unaltered. Long forms of Homer decreased modulation of N- and M-type currents but did not selectively block distinct G-protein pathways. Short forms of Homer, which cannot self-multimerize (Homer 1a and a Homer 2 C-terminal deletion), did not alter mGluR-ion channel coupling. When coexpressed with long forms of Homer, short forms restored the mGluR1a-mediated calcium current modulation in an apparent dose-dependent manner. Homer 2b induced cell surface clusters of mGluR5 in SCG neurons. Conversely, a uniform distribution was observed when mGluR5 was expressed alone or with Homer short forms. These studies indicate that long and short forms of Homer compete for binding to mGluRs and regulate their coupling to ion channels. In vivo, the immediate early Homer 1a is anticipated to enhance ion channel modulation and to disrupt coupling to releasable intracellular calcium pools. Thus, Homer may regulate the magnitude and predominate signaling output of group I mGluRs.

Animals↗
PubMed2000

Dissecting the nucleotide binding properties of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase with fluorescent 3'(2)'-o-anthraniloyladenosine 5'-triphosphate.

6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7, 8-dihydropterin, the first reaction in the folate biosynthetic pathway. Like other enzymes in the folate pathway, HPPK is an ideal target for development of antimicrobial agents because the enzyme is essential for microorganisms but is absent from humans and animals. Using 3'(2')-o-anthraniloyladenosine 5'-triphosphate as a fluorescent probe, a fluorometric competitive binding assay has been developed for measuring the dissociation constants of various compounds that bind to the ATP site of HPPK. The fluorometric assay has been used to determine the nucleotide specificity and dissect the energetics of the binding of MgATP. The order of affinity of various nucleoside triphosphates for HPPK is MgATP>MgGTP>MgITP>MgXTP approximately MgUTP approximately MgCTP. The affinity of MgATP for HPPK (K(d)=2.6+/-0.06 microM) is 260-fold higher than that of MgGTP and more than 1000-fold higher than those of the other nucleoside triphosphates, indicating that HPPK is highly specific with respect to the base moiety of the nucleotide. The affinity of ATP for HPPK in the presence of Mg(2+) is 15 times that in the absence of Mg(2+), indicating that the metal ion is important for the binding of the nucleotide. Removal of the gamma-phosphate from MgATP reduces its affinity for HPPK by a factor of approximately 21. The affinity of AMP for HPPK is about one third that of ADP and almost the same as that of adenosine. The result suggests that among the three phosphoryl groups of MgATP, the gamma-phosphoryl group is most critical for binding to HPPK and the alpha-phosphoryl group contributes little to the binding of the nucleotide. The affinity of MgATP is 18 times that of MgdATP, indicating that the 2'-hydroxyl group of MgATP is also important for binding. van't Hoff analysis suggests that binding of MgATP is mainly driven by enthalpy at 25 degrees C and the entropy of binding is also in favor of the formation of the HPPK.MgATP complex.

Binding, Competitive↗
PubMed2000

Microencapsulation and characterization of tramadol-resin complexes.

Tramadol was complexed with a sulfonic acid cation-exchange resin by a column method. Microencapsulation of tramadol-resin complexes (TRC) was carried out by the spray-drying method. The effect of ethylcellulose (EC) of various viscosities, different solvent systems and addition of plasticizers on microencapsulation were investigated. The morphology of microcapsules was characterized by scanning electron microscopy (SEM). Selected solvents having similar toxicity levels while various physico-chemical properties resulted in greatly different microcapsules. Regular particle morphology and sustained-release behavior were obtained when dichloromethane or ethyl acetate was used as the solvent system, whereas ethanol produced a substantial number of coalesced microcapsules and acetone produced apparently surface-smooth monomicrocapsules with faster release behavior. Three kinds of plasticizers affected the drug release rate similarly. On the addition of plasticizer (DEP), the drug release rate from the microcapsule obtained from low viscosity-grade EC reduced, while there was no alternation for those obtained from middle viscosity-grade EC. Compared to EC with a viscosity of 100 cP, which produced multi-microcapsules and released 60% of the drug within 1 h, microcapsules prepared with 10, 20 and 45 cP viscosity-grade EC showed slower drug release and regular and smooth morphology.

Delayed-Action Preparations↗