Biomedical subjects
Publications and source records attributed to Y Xu.
This paper deals with the phospholipid components in Danggui (Angelica sinensis and Levisticum officinale) by using thin-layer chromatographic scanning and the corrective method of absorbance proportional coefficient. Seven known and two unknown phospholipid components were separated and determined. The authors have compared the composition of phospholipids for six Danggui samples.
The tensile properties of TMJ discs in dogs were investigated using soft-tissue tensile and stress-relaxation tests. The data obtained suggested that (1) the mediolateral tensile stiffness (199.7 and 234.0 MPa), tensile strength (46.73 and 69.99 MPa), and equilibrium moduli (30.0 and 30.1 MPa) of anterior and posterior bands of the disc, respectively, were much greater than those of the middle part (46.6, 14.71, and 18.4 MPa, respectively); (2) the difference in fracture strain of various parts was not significant; (3) the physiologic strain region of the discs was about 4%; and (4) the properties of low stress/relaxation rate and nonlinear relationship of the instantaneous elastic response to various strains may represent lower permeability of TMJ discs.
Understanding the dissolution mechanisms involved in calcium pyrophosphate dihydrate (CPPD) crystals may prove important for the development of therapy for CPPD arthropathy. We demonstrate that yeast pyrophosphatase effectively dissolved CPPD crystals in solutions. Maximum enzymatic dissolution of CPPD crystals was achieved at neutral pH and when the enzyme had access to the crystal surface. The enzymatic dissolution of CPPD crystals was highly dependent on ambient [Mg++] and [Ca++]. The stimulating effects of Mg++ on crystal dissolution in the presence of the enzyme is due to stimulation of pyrophosphatase activity and to enhanced direct release of pyrophosphate ions from the crystal surface. The inhibiting effect of Ca++ on crystal dissolution by the enzyme is mainly due to the suppression of pyrophosphatase activity.
Chinese tea can inhibit the occurrence of oesophageal tumours not only by blocking the formation of N-nitrosomethylbenzylamine (NMBzA) in vivo, but also by inhibiting the carcinogenesis of preformed NMBzA. The incidence of oesophageal tumours in rats intubated with preformed NMBzA (5 mg/kg bw per week) and with the precursors of NMBzA (methylbenzylamine, 1 mM/kg bw; nitrite, 0.5 mM/kg bw) without Chinese tea was higher than in tea-treated groups; the same tendency was found with regard to the severity of the oesophageal lesions. The anticarcinogenic effects of five varieties of Chinese tea were different from one another.
Both daunorubicin and doxorubicin were found effective in inhibiting proliferation of rabbit conjunctival fibroblasts in vitro. The 50% inhibition dose for daunorubicin was 0.14 micrograms/ml, and 0.46 micrograms/ml for doxorubicin, the former being stronger. The authors were hopeful that these drugs would prove useful in preventing cicatrization after glaucoma filter surgery.
Three polysaccharides AC-A, AC-B, AC-C were isolated and purified from the water extract of the root of Cynanchum auriculatum. The molecular weight of AC-A, AC-B and AC-C were 28000, 51000 and 117000 respectively. All these polysaccharides were composed of rhamnose, arabinose, xylose, galactose, mannose and glucose.
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The Rat 3-3 is a secondary transformant of the rat fibroblast cell line (Rat-1) transfected with total DNA of a gastrocarcinoma cell line BGC-823. The cells over-express the c-Ha-ras oncogene which contains point mutation at the 12th codon. In order to determine how the activated c-Ha-ras oncogene expression governs the cell's transformation, two pentadecadeoxy-nucleotides AS-1 and AS-2 were synthesized. AS-1 was complementary to the single strand of the first three codons and the upstream sequence close to the ribosome binding site of c-Ha-ras mRNA. AS-2 was complementary to the 3' end of the first intron and the 5' end of the second exon of c-Ha-ras unripe RNA enclosed in the nucleus. The oligonucleotides could block either the translation of c-Ha-ras mRNA or the splicing of c-Ha-ras unripe RNA, thus inhibiting the expression of the activated c-Ha-ras oncogene and the proliferation of the transformed cells Rat 3-3. The inhibitory effect increased with a growing concentration of the antisense oligodeoxynucleotide (from 4-10 mumol/L) and reached its peak at 12 h after Rat 3-3 was treated with AS-1 and AS-2. This effect became weaker afterwards. The p21 level, product of c-Ha-ras, in the Rat 3-3, was examined by ELISA method. The result shows that the amount of p21 in the growth-inhibited cells is about 30% of that of the control cells.
The degree of physical maturity of children with learning disability and that of normal children were compared by measuring, the difference between skeletal age and chronological age. The findings showed that the number of retarded children was significantly more in with children learning disability than in the normal group, and that the full Scale IQs, the Verbal IQs and the Performance IQs in the retarded children group were all lower than those in the advanced and normal children group. The results suggest that the degree of physical maturity of children is closely related to the intelligence of children, that the retardation of physical maturity plays an important role in causing learning disability.
Rotation function studies of two tetragonal crystal forms of human C-reactive protein have confirmed the pentameric structure of the molecule. The two crystal forms have space groups P4122 (I) and P4222 (II) with closely similar unit cells and are often twinned together. Investigation of the crystallization conditions indicates that dissociation heterogeneity has been a major limiting factor in the reproducible growth of good single crystals. The orientation of the pentameric molecule is shown to be almost identical in both forms, about the axial direction omega = 57 degrees, phi = 45 degrees, i.e. 57 degrees away from c in the (110) plane.
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