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Biomedical subjects

B Xiao

Publications and source records attributed to B Xiao.

At least 91 records · Page 5Linked to original sources
PubMed1998

[Application of coronal CT scan and three-dimensional reconstruction in rhinology].

To display the structure of the Ostiomeatal Complex (OMC) more clearly, and provide clearer and more living imaging for safe functional endoscopic sinus operation and thoroughly eliminating the focus of disease, coronal CT scanning and 3-dimensional reconstruction were performed in 168 sinusitis patients (290 sides) and 107 patients with sinusitis and nasal polyposis (175 sides). The CT findings were compared with endoscopic examination and normal people were taken as control. The found of coronal CT and endoscopic examination are consistent in recognizing mucosal thickening within nasal cavity and sinuses. Three-dimensional CT is more living than common coronal CT in displaying the uncinate process and turbinates. Our conclusion is that coronal CT scan processes high values for recognizing nasal sinus disease, anatomical variants, disease extent and adjacent structures of OMC. Three-dimensional reconstructed CT make the image of OMC more stereoscopic, audio-visual and living.

Adult↗
PubMed1997

The structure of the GTPase-activating domain from p50rhoGAP.

Members of the Rho family of small G proteins transduce signals from plasma-membrane receptors and control cell adhesion, motility and shape by actin cytoskeleton formation. They also activate other kinase cascades. Like all other GTPases, Rho proteins act as molecular switches, with an active GTP-bound form and an inactive GDP-bound form. The active conformation is promoted by guanine-nucleotide exchange factors, and the inactive state by GTPase-activating proteins (GAPs) which stimulate the intrinsic GTPase activity of small G proteins. Rho-specific GAP domains are found in a wide variety of large, multi-functional proteins. Here we report the crystal structure of an active 242-residue C-terminal fragment of human p50rhoGAP. The structure is an unusual arrangement of nine alpha-helices, the core of which includes a four-helix bundle. Residues conserved across the rhoGAP family are largely confined to one face of this bundle, which may be an interaction site for target G proteins. In particular, we propose that Arg 85 and Asn 194 are involved in binding G proteins and enhancing GTPase activity.

Amino Acid Sequence↗
PubMed1997

Safety, efficacy, and acceptability of medical abortion in China, Cuba, and India: a comparative trial of mifepristone-misoprostol versus surgical abortion.

OBJECTIVE: We investigated safety, efficacy, and acceptability of an oral regimen of medical abortion compared with surgical abortion in three developing countries. STUDY DESIGN: Women (n = 1373) with amenorrhea < or = 56 days chose either surgical abortion (as provided routinely) or 600 mg of mifepristone followed after 48 hours by 400 micrograms of misoprostol. This is the appropriate design for studying safety, efficacy, and acceptability among women selecting medical abortion over available surgical services. RESULTS: The medical regimen had more side effects, particularly bleeding, than did surgical abortion but very few serious side effects. Failure rates for medical abortion, although low, exceeded those for surgical abortion: 8.6% versus 0.4% (China), 16.0% versus 4.0% (Cuba), and 5.2% versus 0% (India). Nearly half of failures among medical clients were not true drug failures, however, but surgical interventions not medically necessary (acceptability failures or misdiagnoses). Women were satisfied with either method, but more preferred medical abortion. CONCLUSION: Medical abortion can be safe, efficacious, and acceptable in developing countries.

Abortifacient Agents↗
PubMed1997

Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD.

From approximately one week before normal ovulation resumes, lactating women require protection against pregnancy by a contraceptive that is safe for both infant and mother in a multicenter one-year study, the natural hormone, progesterone, delivered vaginally by a sequence of four contraceptive rings designed for continuous use, was evaluated as a contraceptive for nursing mothers in comparison with the Copper T 380A IUD. Individual rings release in effective average dose of 10 mg day for a 3 month period. Evaluation included measures of lactational performance as well as of contraceptive efficacy and safety to mother and child. Nine participating clinics enrolled 802 ring users and 734 IUD acceptors between postpartum days 29 and 63. Life table analyses were performed with parallel decrements for ring and IUD subjects. Continuation in the study and analysis required that subjects not stop breastfeeding. The ring, with a one-year pregnancy rate of 1.5 per 100, did not differ significantly from the IUD with respect to contraceptive effectiveness (p > 0.05). More than half of the ring subjects were continuing at 6 months post admission and a quarter (23.5 per hundred) were still using the ring and breastfeeding one year after admission. Women with the IUD, however, had higher continuation rates (p < 0.001) at both time points. The largest single decrement for each method was that for weaning. Ring users had more complaints of vaginal problems but had fewer vaginal disorders on examination. At 12 months postpartum, 46 per 100 continuing ring users remained in amenorrhea. Lactation performance and the health and weight gain of the infants were similar among users of either regimen.

Administration, Intravaginal↗
PubMed1997

Effect of once weekly administration of mifepristone on ovarian function in normal women.

The effects of mifepristone on ovarian function during a once weekly oral administration regimen were studied in nine healthy women. Each received 25 mg mifepristone on cycle days 3, 10, 17, and 24. Ovulation, as documented by hormonal measurements and ultrasonography, was inhibited during treatment in five subjects, with a midcycle surge of luteinizing hormone and ovulation occurring 6-18 days after the last pill was administered in four of the five subjects. These five treatment cycles were prolonged 9-26 days. The other four subjects had normal cycles as judged by serum hormone levels, ultrasonography, and cycle length. All nine subjects had delayed endometrial growth as indicated by ultrasonography. There was a significant correlation between concentrations of serum mifepristone (10 h and 58 h) and alpha 1-acid glycoprotein, the protein to which mifepristone binds in circulation. Response to mifepristone did not depend on its circulating levels. We conclude that once weekly administration of 25 mg mifepristone can interfere with normal follicular development and function, but the inhibition of ovulation was inconsistent.

Adult↗
PubMed1997

[Effects of lanthanum and cerium on malignant proliferation and expression of tumor-related gene].

Cultured human gastric cancer cell line PAMC82 was studied in vitro to further verify anti-tumor effect sof rare-earth elements and explore their mechanism of tumor inhibition. Inhibitory effects of elements lanthanum and cerium on cell growth, reverse effects of them on reduction of malignancy and effects of them on level of expression of oncogene and cancer suppressor gene were observed. Lanthanum chloride, cerium chloride and mixed rare-earth chloride at levels of 0.5 to 1.5 mmol/L could inhibit obviously growth of cancer cells and change cell morphology and microtubule structure of PAMC82, similar to that of normal cells, their colony-forming ability lowered in soft agar, and expression of tumor suppressor gene p53, p16 and p21 increased and that of gene nm23 lowered.

Antineoplastic Agents↗
PubMed1997

[Electromyogram (EMG) and muscle biopsy in patients with chronic spinal muscular atrophy].

The clinicopathological changes were investigated by electromyogram (EMG) and muscle biopsy in 30 cases of chronic spinal muscular atrophy. The results showed that the denervating changes were demonstrated in EMG in all patients but two. The light microscope discovered manifestation of neurogenic atrophy, and the electron microscope revealed a reduction of myofibrils, thickening and wavy appearance of Z-lines and dilation of mitochondria and endoplasmic reticula.

Adolescent↗
PubMed1996

Crystallization of a 14-3-3 protein.

Crystals of the tau (tau) isoform of the 14-3-3 family of proteins were grown and shown to belong to the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 70.29, b = 79.3, c = 101.00 A. The crystals were needle-like in morphology and less than 10 micro m in two dimensions. Diffraction data were collected using synchrotron radiation sources from flash-cooled crystals. Native data extended to a resolution of 2.6 A and mercury and platinum derivatives diffracted to 3.4 and 3.9 A, respectively. The structure has been solved recently. Here the protein crystallization procedures, the characterization of the crystals and the correlation between crystal habit and diffraction quality are reported.

Journal Article↗
PubMed1996

[Emergency contraception with mifepristone and anordrin].

OBJECTIVE: To study the efficacy of mifepristone or with anordrin for emergency contraception. METHODS: 300 healthy women were recruited within 7.2 hours after unprotected intercourse or contraceptive failure and randomly allocated into 3 groups. Group 1 (n = 100), mifepristone 25 mg twice with 12 hours apart; group 2 (n = 99), single dose of mifepristone 25 mg; and group 3 (n = 101), mifepristone 25 mg and anordrine 7.5 mg given once. RESULTS: No pregnancy occurred in group 1, while 1 pregnancy in each group 2 and 3. The contraceptive effectiveness were 100.0%, 83.8% and 86.1% for the 3 groups respectively. The overall menstruation disturbances and side effects were low. CONCLUSIONS: Both mifepristone 50 or 25 mg were effective for emergency contraception and no synergetic effects of anordrin in combination with mifepristone was shown in this study.

Adult↗
PubMed1995

Crystallization and preliminary X-ray analysis of maize ZBP14 protein, a member of a new family of zinc-binding proteins.

A preliminary X-ray crystallographic study of a novel zinc-binding protein from maize is presented. Native and several heavy-atom derivative sets of data have been collected on synchrotron sources, to a resolution of 2.1 A. The space group was found to be orthorhombic, P2(1)2(1)2(1), with unit-cell dimensions of a = 92.64, b = 129.45 and c = 196.31 A.

Journal Article↗
PubMed1995

Structure of a 14-3-3 protein and implications for coordination of multiple signalling pathways.

A broad range of organisms and tissues contain 14-3-3 proteins, which have been associated with many diverse functions including critical roles in signal transduction pathways, exocytosis and cell cycle regulation. We report here the crystal structure of the human T-cell 14-3-3 isoform (tau) dimer at 2.6 A resolution. Each monomer (Mr 28K) is composed of an unusual arrangement of nine antiparallel alpha-helices organized as two structural domains. The dimer creates a large, negatively charged channel approximately 35 A broad, 35 A wide and 20 A deep. Overall, invariant residues line the interior of this channel whereas the more variable residues are distributed on the outer surface. At the base of this channel is a 16-residue segment of 14-3-3 which has been implicated in the binding of 14-3-3 to protein kinase C.

14-3-3 Proteins↗
PubMed1995

Effect of levonorgestrel-releasing intrauterine device on hormonal profile and menstrual pattern after long-term use.

In the present study 14 women after 6 years' use of levonorgestrel-releasing IUD were investigated for the changes of LH, progesterone (P), estradiol (E2), prolactin (PRL) and serum binding globulin (SHBG) in relation to the levonorgestrel levels throughout a segment of 26-40 days with the aim of comparing the hormonal profiles with those during the first year of use of Lng-IUD. Ultrasound scanning was used to follow the development of follicles along with the RIA measurement of hormones. The results of serum LH, P and E2 showed ovulation in 11 cases with either normal menstrual cycles (5 cases), prolonged or irregular cycles (4 cases) or with amenorrhea for 2-3 years (2 cases). One case showed insufficiency of luteal function and 2 cases showed anovulation but with follicular hyperactivity. Higher percentages of ovulatory cycles (78.5%) were found after 6 years of use. No case of complete suppression of ovulation was found. Anovulatory cycles only constituted 14.3%. Clinically, the development of follicles followed by ultrasound scanning further confirmed the hormonal findings. The persistent enlargement of follicles coincided with high levels of E2. After 6 years of use, the serum levels of levonorgestrel were still maintained at mean levels of 314.26 pmol/L and 470.63 pmol/L in the ovulatory and anovulatory groups, respectively. It is concluded that over two-thirds of the cases have ovulatory cycles after long-term use of Lng-IUD; the contraceptive effect is mainly due to its local action on the endometrium, with much less effect on the ovarian function.

Adult↗
PubMed1995

[Epidemiological studies on endemic fluorosis and arsenism in Xinjiang].

Epidemiological and clinical studies on the water of 102 wells containing high-level fluoride and arsenic and a population of 50,760 drinking the water in Kuitun Area, Xinjiang were conducted. Results indicated fluoride and arsenic contents in the well water were associated with geochemical environment, and drinking the water containing high-level fluoride and arsenic for a long-term was the cause of fluorosis and arsenism. Also, diagnostic criteria and major clinical manifestations for fluorosis and arsenism were put forward in the paper. Relationship between fluoride and arsenic contents in the well water and prevalence of fluorosis and arsenism in local residents was analyzed. It suggested fluorosis and arsenism was a systematic disorder and further studies on its potential hazard were merited.

Adolescent↗