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Biomedical subjects

W Yang

Publications and source records attributed to W Yang.

At least 109 records · Page 6Linked to original sources
PubMed2001

Cold crucible levitation melting of biomedical Ti-30 wt%Ta alloy.

Recently, titanium-tantalum alloys have been studied as implant materials for dental and orthopedic surgery. However, titanium and tantalum are difficult to mix by common arc melting and induction melting, because of their high melting point and the marked difference between their densities (Ti: 1,680 degrees C, 4.5 g/cm3, Ta: 2,990 degrees C, 16.6 g/cm3). Thus, the Cold Crucible Levitation Melting (CCLM) method was chosen to produce a Ti-30 wt%Ta binary alloy in the present study. The CCLM furnace, with 1 kg capacity, consisted of a water-cooled crucible comprising oxygen-free high purity copper segments and coils wrapped around the crucible and connected to a frequency inverter power supply. A qualified ingot of 1.0 kg of Ti-30 wt%Ta alloy was obtained. The ingot was characterized from the surface quality, chemical composition distribution and microstructure, and finally the melting process was discussed.

Alloys↗
PubMed2001

[Cloning and expression of nisZ gene in Lactococcus lactis].

The gene encoding the precursor of nisin was amplified by PCR using the lambda HJ-3 DNA as the template, which contained the entire nisin biosynthesis gene cluster from Lactococcus lactis AL2 with high yield of nisin, and was cloned into pMG36e. The recombinant plasmid pHJ201 was introduced into Lactococcus lactis NZ9800 by electroporation. pHJ201 is very stable in L. lactis NZ9800. Antimicrobial activity test and Tricine-SDS-PAGE analysis revealed that L. lactis NZ9800 harbouring pHJ201 restored ability of nisin production, but the production level was markedly lower than L. lactis AL2. The result of DNA sequence analysis indicated that Nisin Z is produced by L. lactis AL2.

Amino Acid Sequence↗
PubMed2001

[Cloning, expression and purification of the chicken growth and differentiation factor-8].

Growth and Differentiation Factor-8(GDF-8) is a new member of TGF-beta super-family. It has been shown that GDF-8 is specifically expressed in skeleton muscle in mouse and its function is to inhibit the growth of muscle cell, so it is named as Myostatin. Here, we amplified 3'half-length GDF-8 cDNA from chicken skeleton muscle by RT-PCR, and cloned it into the prokaryotic expression vector pTrcHisB, which was then transformed into E. coli Top10 cells. The recombinant 6 x His-GDF-8 fusion protein expressed in the Top10 cells was purified by Ni(+)-Affinity Chromatography for future study.

Animals↗
PubMed2001

Boron neutron capture therapy of brain tumors: investigation of urinary metabolites and oxidation products of sodium borocaptate by electrospray ionization mass spectrometry.

Boron neutron capture therapy (BNCT) is based on a nuclear capture reaction that occurs when boron-10, a stable isotope, is irradiated with low energy neutrons to produce high-energy alpha particles and recoiling lithium-7 nuclei. The purpose of the present study was to determine what urinary metabolites, if any, could be detected in patients with brain tumors who were given sodium borocaptate (BSH), a drug that has been used clinically for BNCT. BSH was infused intravenously over a 1-h time period at doses of 26.5, 44.1, or 88.2 mg/kg of body weight to patients with high-grade brain tumors. Electrospray ionization mass spectrometry has been used to investigate possible urinary metabolites of BSH. Chemical and instrument conditions were established to detect BSH and its possible metabolites in both positive and negative electrospray ionization modes. Using this methodology, boronated ions were found in patients' urine samples that appeared to be consistent with the following chemical structures: BSH sulfenic acid (BSOH), BSH sulfinic acid (BSO(2)H), BSH disulfide (BSSB), BSH thiosulfinate (BSOSB), and a BSH-S-cysteine conjugate (BSH-CYS). Although BSH has been used clinically for BNCT since the late 1960s, this is the first report of specific biotransformation products following administration to patients. Further studies will be required to determine both the biological significance of these metabolites and whether any of these accumulate in significant amounts in brain tumors.

Biotransformation↗
PubMed2001

[Sequence analysis of mtDNA 12S rRNA, tRNA(Leu(UUR)),tRNA(Ser(UCN))and 16S rRNA gene of 12 nonsyndromic inherited deafness pedigrees].

OBJECTIVE: To detect the relationship of mtDNA mutation with inherited deafness and the reason for pedigree's hypersensitivity to ototoxicity of aminoglycoside antibiotics(AmAn). METHODS: Pedigree investigations were conducted. The blood samples were obtained from 12 pedigrees, and DNA was extracted from the isolated leukocytes. After that, mtDNA fragments were amplified by PCR. The 1555(G), 3243(G) and 7445(G) mutations were detected by Alw 26 I, Apa I and Xba I restriction endonuclease digestion respectively, and then sequencing of 12S rRNA, tRNA(Leu(UUR)), tRNA(Ser(UCN))and 16S rRNA gene was performed. RESULTS: Restriction endonuclease digestion and sequence analysis showed that all the pedigrees carried mtDNA mutation, among them, 10 pedigrees carried 1555(G) mutation; 2 pedigrees, 7445(G) mutation; no pedigree was found to harbor the 3243(G) mutation. Sequence analysis of 16S rRNA gene showed that the mutations are 2230(G), 2230(AG), 2243(AG), 2230(AA). CONCLUSION: The pedigrees that carried 1555(G) or 7445(G) mutation showed hereditary or congenital hearing loss. The 1555(G) or 7445(G) mutation in association with 16S rRNA gene mutation led to pedigree's hypersensitivity to AmAn ototoxicity.

Base Sequence↗
PubMed2001

[Expression of vascular endothelial growth factor in placenta from pregnancy complicated with pregnancy induced hypertension].

OBJECTIVE: To study the expression of vascular endothelial growth factor (VEGF) in placenta from normal pregnancy and pregnancy complicated with pregnancy induced hypertension (PIH) and the effect of VEGF on the etiology of PIH. METHOD: Use the immunohistochemistry to determine the location and intensity of VEGF staining in placenta from 21 cases of normal pregnancy and 62 cases of mild, moderate and severe group of pregnancies complicated with PIH. RESULT: Immunolocalization of VEGF in all cases was observed mainly in syncytiotrophoblast. Intensity of VEGF immunostaining in syncytiotrophoblast was significantly reduced in the moderate PIH group (P < 0.05) and the severe PIH group (P < 0.01) compared with both the mild PIH group and the normal group, while there was no qualitative differences between the mild PIH group and the normal group. Intensity of staining in decidual cells was also similar in all the groups. CONCLUSION: These results suggest that VEGF is secreted mainly by syncytiotrophoblast in human placenta and the reduced VEGF may be responsible, at least in part, for the impaired vascular development in PIH.

Adult↗
PubMed2001

Analysis of hypermutation of the 5' noncoding region in the BCL-6 gene.

OBJECTIVE: To investigate BCL-6 gene mutations in Chinese populations with B-cell non-Hodgkin's lymphoma. METHODS: Polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct DNA sequencing were used to identify mutations in the 5' noncoding region of the BCL-6 gene in a total of 40 cases of diffuse large-cell lymphoma (DLCL) and follicular lymphoma (FL). RESULTS: Nine cases were found to have base substitutions. The incidence of BCL-6 gene mutation and the frequency of single-base changes were approximately 25.7% and (0.56-1.10) x 10(-2)/bp, respectively. CONCLUSIONS: The 5' regulatory region of the BCL-6 gene undergoes frequent somatic hypermutation during lymphomagenesis and the identification of BCL-6 gene hypermutations provides a molecular marker for confirmatory diagnosis of B-NHL.

5' Flanking Region↗
PubMed2001

Cholinergic agonists increase intracellular calcium concentration in guinea pig vestibular hair cells.

OBJECTIVE: To better understand the cholinergic receptors in vestibular hair cells (VHC) and their subtypes, and to investigate the effects of cholinergic agonists on intracellular calcium concentration ([Ca2+]i) in guinea pig VHCs. METHODS: VHCs were isolated from guinea pig crista ampullaris by enzymatic and mechanical methods. The effect of cholinergic agonists on [Ca2+]i was examined using laser scanning confocal microscopy and the Ca2+ sensitive dye Fluo-3. RESULTS: The results showed that the addition of acetylcholine (ACh) and carbachol (CCh), muscamic and nicotinic agonists, induced [Ca2+]i increases in all the VHCs, whereas acetylcholine bromide (ACh-Br), a nicotinic agonist, induced the [Ca2+]i increase in only a small percentage of VHCs. The ACh or CCh-induced Ca2+ response could be partially suppressed by atropine. In the presence of 0.1 mmol/L atropine, the amplitudes of ACh or CCh-induced [Ca2+]i responses became significantly smaller than those in atropine free medium (P < 0.01). CONCLUSIONS: The results suggest the existence of cholinergic receptors in guinea pig VHCs. It is the muscamic agonists rather than nicontic receptors that dominate [Ca2+]i variation. Atropine can suppress muscamic agonist-induced Ca2+ responses.

Acetylcholine↗
PubMed2001

Regional glucose metabolic increases in left auditory cortex in tinnitus patients: a preliminary study with positron emission tomography.

OBJECTIVE: To investigate the relationship between tinnitus and glucose metabolism in auditory cortex and whether positron emission tomography (PET) can be an objective tool in measuring tinnitus. METHODS: Eleven right-handed patients with severe tinnitus and ten right-handed control subjects participated in the 18F-FDG/PET study. Analysis with regions of interests was used to calculate asymmetry indices according to the formula: [(L-R) x 100/[(L + R) divided by 2]]. RESULTS: Glucose metabolism in the auditory cortex of tinnitus patients was asymmetric between the left and right auditory cortices, with that of the left being much higher than that of the right. The asymmetry indices of tinnitus patients was significantly higher than that of the control group (unpaired t test, P < 0.001). This revealed that the increased metabolic activity was present in the predominant left hemisphere with a significant focus on the superior and transverse temporal gyri (Brodmann areas 41 and 42, respectively corresponding to primary and secondary auditory cortex), and the results were independent of the subjective localization of the tinnitus sensation. CONCLUSION: It is suggested that the increased metabolism in the left auditory cortex is related to the tinnitus sensation. PET is capable of providing objective evidence for tinnitus and may be used as a potential tool in measuring tinnitus.

Adolescent↗
PubMed2001

Efficacy of dihydroartemisinin-mefloquine on acute uncomplicated falciparum malaria.

OBJECTIVE: To evaluate the clinical efficacy of dihydroartemisinin-mefloquine on acute uncomplicated falciparum malaria. METHODS: Fifty-four patients with symptomatic falciparum malaria were allocated to receive oral dihydroartemisinin at a single dose of 120 mg on day 1, followed by mefioquine, 750 mg and 500 mg on days 2 and 3, respectively. Follow-up was performed on days 1, 2, 3, 4, 7, 14, 21, and 28. RESULTS: All patients had a rapid initial response to treatment. The parasite clearance time (PCT) after treatment was 30.7 +/- 3.6 hours. The fever subsidence time (FST) after treatment was 21.2 +/- 2.8 hours. Two patients had a recrudescence 21 and 25 days respectively after the disappearance of parasitemia, hence the recrudescence rate was 3.7% and the cure rate was 96.3%. No serious adverse effects were observed, only mild and transient nausea, vomiting and loss of appetite. CONCLUSION: A combination of dihydroartemisinin and mefloquine is effective in the treatment of acute uncomplicated falciparum malaria.

Acute Disease↗
PubMed2001

[The role of CA125 in the differential diagnosis of primary ovarian carcinoma and metastatic ovarian carcinoma originated from the gastrointestinal tract].

OBJECTIVE: To assess the role of CA125 monoclonal antibody in the differential diagnosis of primary ovarian carcinoma and metastatic ovarian carcinoma originated from the gastrointestinal tract. METHODS: Immunohistochemical study using CA125 monoclonal antibody was performed on 33 primary ovarian cancer and 50 metastatic ovarian cancer of gastrointestinal origin. RESULTS: The positivity of CA125 was 84.5% in 33 cases of primary ovarian carcinoma, while in 50 metastatic ovarian carcinoma cases, only 4.0% was CA125 positive. The positivity of CA125 was significantly higher in primary ovarian carcinoma than metastatic ovarian carcinoma (P < 0.001). CONCLUSION: CA125 monoclonal antibody is useful in the differential diagnosis of ovarian carcinoma.

CA-125 Antigen↗
PubMed2001

[A study of injectable autologous tissue engineering cartilage].

OBJECTIVE: To study the regeneration of injectable autologous cartilage in New Zealand rabbits model. METHODS: Chondrocytes were harvested from auricle of New Zealand rabbits. The cells were mixed with sodium alginate (SA) and temperature dependent synthetic hydrogel (TDSH) to generate final cellular density of 50 x 10(9)/L, and then the chondrocytes-SA and chondrocytes-TDSH composites were injected into the dorsal subcutaneous tissue of New Zealand rabbits with form of autologous cells grafts respectively. The specimen and histology were observed in the process of cartilage fabrication in 4, 8, 12 weeks. RESULTS: Four weeks after injection, the hard knobbles were formed subcutaneously. Eight and twelve weeks after injection, the knobbles was much harder and showed the appearance of cartilage. In histological analysis, the immature cartilage can be observed after 4 weeks. In the eight and twelve weeks, the mature cartilage was formed and showed strong GAG positive expressed by safranine-O. CONCLUSIONS: Neocartilage could be regenerated through injection of alginate and synthetic hydrogel mixed with chondrocytes. Using tissue-engineering methods, Injectable cartilage may have great potential of clinical use in the future.

Animals↗
PubMed2001

[A clinical study on black diaphragm posterior chamber intraocular lens implantation].

OBJECTIVE: To discuss the effect of black-diaphragm intraocular lens implantation in the management of cataract or aphakia with aniridia. METHODS: Thirty-three cases (34 eyes) of black-diaphragm posterior chamber intraocular lens implantation were retrospectively analyzed, among which 18 eyes had undergone primary intraocular lens implantation and 16 secondary intraocular lens implantation. RESULTS: After 1-52 months of follow-up, postoperative corrected visual acuities were greater-than-or-equal 1.0 in 17 eyes, 0.5-0.9 in 11 eyes and 0.1 -0.4 in 6 eyes. The complications included intraoperative ciliary body bleeding in 2 eyes and retinal detachment in one eye. CONCLUSION: Black-diaphragm intraocular lens implantation is effective in the management of cataract or aphakia with aniridia.

Adolescent↗
PubMed2001

[High efficient expression of recombinant human platelet factor IV in Pichia pastoris].

OBJECTIVE: To express recombinant human platelet factor 4 (PF4) in methanol yeast. METHODS: PF4 cDNA amplified by PCR was cloned into the mating factor alpha (MFalpha) signal sequence, downstream the alcohol oxidase 1 (AOX 1) promoter of the pPIC9 vector. The reconstructed vector was subsequently integrated into the methanol yeast P. pastoris strain GS115. The highly expressing strain was selected and the protein sequences and their biological activities were assayed. RESULTS: The amino acid sequence of rhPF4 was the same as that of natural one. The rhPF4 can neutralize the anticoagulation effect of heparin in a dose-dependent manner. CONCLUSION: The amount of rhPF4 expressed in methanol yeast meets well the scale for manufacturing. The biological activities of the rhPF4 were the same as that of natural PF4.

Cloning, Molecular↗
PubMed2001

[Differential expression of cyclins D1, E and A in human breast diseases].

OBJECTIVE: To understand with greater clearness the effect of overexpression of cyclins gene and the potential implications of it for tumorgenesis in breast. METHODS: We assayed the expression of cyclins D1, E and A in different types of human breast diseases by immunohistochemical staining. RESULTS: Significant difference was seen among the malignant tumor, benign tumor and dysplasis(P < 0.001). The expressive intensity of above three kind of cyclins in malignant tumor was the highest, that in benign tumor was higher, and that in dysplasis was low. CONCLUSION: These data suggest that the expressive intensity of cyclins gene may serve as an indicator for malignant intensity of tumors. The expressive ratio difference of cyclins E and A between infiltrating ductal carcinoma and infiltrating lobular carcinoma may imply that there are different mechanisms involving the occurrence of different histological types of breast tumor.

Breast Neoplasms↗
PubMed2001

[Study on the forensic application of ABO genotyping by PCR-RFLP].

OBJECTIVE: The study was carried out on the application of ABO genotyping by PCR-RFLP to forensic purpose. METHODS: The DNA of samples were extracted by Chelex--100 and phenol/chloroform, the PCR products were separated by Native Horizontal PAGE, and detected by silver staining. RESULTS: The PCR amplified fragment length of ABO loci is from 175 to 210 bp, the frequency distribution of six genotypes ranges from 0.0250 to 0.4300, heterozygosity(H) and discriminating power(Dp) is 0.5162 and 0.7111. CONCLUSION: This technique has a good application to the forensic samples such as blood, blood stain, semen stain, hair root, bone tissue and semen from vaginal swabs.

ABO Blood-Group System↗