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Biomedical subjects

L Tang

Publications and source records attributed to L Tang.

At least 271 records · Page 15Linked to original sources
PubMed1991

Coloning and expression of spiramycin polyketide synthase genes and resistance genes from S. spiramyceticus U-1941.

The plasmid containing the spiramycin polyketide synthase genes, pCN3H8, was obtained from the genomic library of spiramycin producing strain, S. spiramyceticus U-1941, using homologous DNA to actI and actIII genes as hybridization probes. Restriction analysis of the plasmid pCN3H8 showed that the molecular weight was 44kb. The regions homologous to the actI & actIII genes were localized by Southern hybridization, and corresponding DNA fragments were subcloned onto E. coli-Streptomyces shuttle vector pWHM3. A recombinant plasmid pCG4 was obtained. Transformation of the pCN3H8 DNA into the polyketide synthase deficient mutant of midecamycin producing strain, S. mycarofaciens subsp. No. 68, resulted in the production of midecamycin A by UV analysis. Transformation of the pCN3H8 DNA into the polyketide synthase deficient mutant of actinorhodin producing strain, S. coelicolor TK17, resulted in the production of an antibacterial compound which was neither similar to actinorhodin in color nor to spiramycin by paper chromatographic analysis. Transformant of S. lividans with pCN3H8 DNA produced an antibacterial compound as well. Resistance to spiramycin was expressed in transformants of spiramycin sensitive strain, S. griseofuscus, with pCN3H8 DNA. A plasmid pSG3 DNA with molecular weight of 7.0kb, isolated from the transformant, might be a result of in vivo deletion of pCN3H8 in S. griseofuscus. Retransformation of pSG3 DNA into S. griseofuscus confirmed that the gene of resistance to spiramycin was on the plasmid pSG3 DNA. Transformation of spiramycin producing strain, S. ambofaciens, with pCG4 or pSG3 DNA increased spiramycin production in fermentation broth.

Cloning, Molecular↗
PubMed1991

[Pulsed-wave Doppler ultrasound evaluation of flow velocity waveforms of fetal umbilical artery and uterine artery as predictors of neonatal outcome].

A pulsed-wave doppler ultrasound system was used to record arterial flow velocity time waveforms from the fetal umbilical artery (UmA) and the branches of the uterine artery (UtA) in the placental bed in term pregnancies. The systolic-diastolic ratio (S/D) of flow velocity was measured as an index of peripheral resistance in the placental bed. The UmA S/D ratio was measured in 123 pregnant women between 37- less than 42 gestational weeks and the UtA S/D ratio was measured in 121 of them simultaneously. The cutoff value of an abnormal UmA S/D ratio was 3.0 or higher, and UtA S/D ratio 2.5 or higher. Furthermore, the neonatal poor outcome was observed more frequently in both the abnormal ratio groups than in both the normal ratio groups. The sensitivity of the UmA, and UtA S/D ratios to predict an adverse neonatal outcome was 72.7%, 27.3%, respectively. The data showed the abnormal UmA S/D and abnormal UtA S/D ratios were associated with the neonatal poor outcome, but the former was the better test for screening for adverse neonatal outcome.

Arteries↗
PubMed1990

Motion analysis of the cervical spine in athetoid cerebral palsy. Extension-flexion motion.

Frequently instability and premature onset of spondylosis of the cervical spine are found in athetoid cerebral palsy (CP) patients. These structural abnormalities appear to be related to athetoid motion of the neck in CP. Through motion analysis, the authors aimed to clarify the abnormalities of cervical motion that could precipitate structural abnormalities. The gross characteristic feature of cervical motion in athetoid CP is "whip movement." Both velocity and acceleration during extension-flexion motion were greater than in normal subjects, especially at the upper cervical levels. Also, a sudden increase in velocity and acceleration occurred during rapid motions at certain levels, followed by a larger range of motion of the cervical spine. Such kinematic abnormalities were thought to generate a greater shearing force and bending moment exerted on the corresponding cervical articulations-discs and facets. Olisthetic instability often accompanied disc degeneration at the upper cervical levels. A large range of extension--flexion motion of the cervical spine, analogous to a cantilever, caused a repeated bending moment of extraordinary magnitude and was regarded as a precipitative factor for disc degeneration and osteophytosis common at the middle and lower levels of the disc.

Adult↗
PubMed1990

Hormonal studies on women with polycystic ovaries diagnosed by ultrasound.

Eighty-six patients were diagnosed by ultrasound to have polycystic ovaries. Twelve have fairly regular but anovular cycles (P1), 56 had oligomenorrhoea (P2) and eight had primary or secondary amenorrhoea (P3). The remaining 10 patients had raised progesterone concentrations and were excluded from the hormonal studies. Gonadotrophins, steroid hormones and sex hormone binding globulin (SHBG) were measured in all patients and the results were compared with those of 29 normal women who acted as controls. A high LH:FSH ratio was the most frequently found abnormality (raised in 68.4% of patients) followed by LH (65.8%), free testosterone (FT, calculated from total testosterone (T) and SHBG) (59.2%) and 17-OHP (48.7%). Each of these four estimations was above the normal ranges in 25% of patients: proportionally most of the results outside the normal range occurred in group P3 followed by P2 and P1 respectively. To obtain a quantitative measure of the abnormalities, results were expressed as percentages of the mean control value for each hormone and these percentages were then summated. The four measurements, LH:FSH ratio, LH, FT and 17-OHP gave abnormality scores ranging from a mean of 667 in P1 to 1189 in P3 compared with 405 in controls. Twenty-one of the 76 patients were hirsute with significantly higher androgens than the nonhirsute patients. Their mean abnormality score was 1141 compared with 855 in the non-hirsute group and they all had at least one hormonal abnormality. The study demonstrates that there is a relationship between the degree of hormonal abnormality and the menstrual irregularities and hirsutism in women with PCOS suggesting that there may be a progressive nature to the syndrome.

17-alpha-Hydroxyprogesterone↗
PubMed1990

Caesarean section for the birth of the second twin.

Twin pregnancies delivered after 28 weeks gestation between 1980 and 1988 were reviewed. Of 510 twin pregnancies, 184 (36%) were delivered by caesarean section. There were 22 (4.3%) combined vaginal/abdominal deliveries which comprised 12% of the 184 twin pregnancies delivered by caesarean section. Persistent transverse lie or a high breech presentation was the commonest indication for caesarean section for the second twin.

Breech Presentation↗
PubMed1990

Intramural pericyte degeneration in early diabetic retinopathy study in vitro.

An experimental model of diseased pericytes was established by using cultured bovine retinal capillary pericytes in high--glucose medium. The high glucose stimulated polyol pathway, reduced cellular myo-inositol content and disturbed inositol phospholipid metabolism which resulted in a decrease in inositol trisphosphate (IP3) level. The correlation of suppressed IP3 levels with reduced DNA synthesis was evident. These findings suggested the biochemical mechanism by which retinal pericytes degenerate in high glucose. To supplement myo--inositol and/or an aldose reductase inhibitor to the high--glucose medium largely reversed the suppressed IP3 level and the decreased DNA synthesis. Therefore, these two manipulations may be considered as in vitro therapy to treat sick pericytes induced by high glucose.

Animals↗
PubMed1989

Characterization of tubulin from Brugia malayi and Brugia pahangi.

The tubulins of Brugia malayi and B. pahangi were similar with respect to concentration (mg tubulin per mg soluble protein), electrophoretic and isoelectric mobility, reaction in Western blots with anti-tubulin monoclonal antibodies, and isoform patterns. Tubulin was estimated to account for 2.8% and 2.9% of soluble protein in B. malayi and B. pahangi extracts, respectively. Tubulins from Brugia nematodes have been partially purified by polylysine agarose chromatography and with taxol. Western blots with alpha- and beta-tubulin monoclonal antibodies confirmed the presence of tubulin. The mobility of Brugia tubulins on sodium dodecyl sulfate polyacrylamide gel electrophoresis was very similar to that of N. brasiliensis and rat brain tubulins. The isoelectric range for Brugia alpha- and beta-tubulin isoforms was pH 5.4-4.7. Western blots with anti-tubulin monoclonal antibodies revealed 4-5 isoforms of alpha-tubulin and 4-5 isoforms of beta-tubulin for Brugia nematodes.

Animals↗
PubMed1989

Attenuation of phosphoinositidase activity and phosphatidylinositol bisphosphate level of bovine retinal capillary pericytes in high glucose.

Both phosphoinositidase (PIase) and individual species of inositol phospholipid (IPL) of bovine retinal capillary pericytes (BRCP) were quantitatively determined. When glucose in growth medium was increased from 5- to 15- or 30 mM, PIase activity was attenuated to 82% or 55%, respectively. In contrast, when glucose (5-, 15-, 30 mM) was added to an enzyme extract from cells grown in the standard growth medium (5 mM glucose, 0.04 mM myo-inositol) the PIase activity was not changed, indicating that the reduced PIase activity was not due to the direct effect of glucose. When IPLs from BRCP were analysed by HPLC and TLC, we observed reduction of the total and newly formed IPLs including the substrate of PIase. Phosphatidylinositol bisphosphate (PIP2). Reduced levels of IPLs were associated with a decrease in myo-inositol and an increase in sorbitol. The changes in IPL metabolism were reversed by adding either free myo-inositol or AL1576, an aldose reductase inhibitor (ARI), to the high-glucose medium. However, the addition of myo-inositol to the growth medium with a standard concentration of glucose only caused a marked increase in phosphatidylinositol, but not in PIP or PIP2, while the supplement of AL1576 in the standard medium did not cause any changes in IPL formation. These findings suggest that the alteration in IPL metabolism in BRCP may be related to insufficient myo-inositol or activated sorbitol pathway under high-glucose conditions. Further explanation of the role of the altered hydrolysis of PIP2 triggered by PIase may provide clues to understanding of the mechanism of decreased pericyte viability in the presence of high glucose concentrations.

1-Phosphatidylinositol 4-Kinase↗
PubMed1989

DNA-synthesis regulation and correlation with inositol trisphosphate levels in cultured bovine retinal capillary pericytes.

Inositol phosphate (IP), inositol bisphosphate (IP2) and inositol trisphosphate (IP3) in cultured bovine retinal capillary pericytes (BRCP) were quantitated by an ion-pair reverse-phase HPLC. BRCP were grown in media with standard (5 mM) or high (30 mM) glucose, and were either labeled with myo-[2-3H]inositol (20 microCi ml-1) for 60 hr or with dual isotopes (20 microCi ml-1 myo-[2-3H]inositol and 2 microCi ml-1 [14C]glycerol) for 8 hr. In parallel, BRCP in different glucose-media were incubated with 1 microCi ml-1 [3H]thymidine for 4 hr. High glucose significantly suppressed the accumulation of [3H]label in IP, IP2 and IP3, and specifically reduced the incorporation of [14C]glycerol into inositol phospholipids, but not that of neutral lipids and other types of phospholipids. The reduced IP3 level correlated with the decrease in the incorporation of [3H]thymidine into DNA. Both the reduced IP3 formation and DNA synthesis which were induced by high glucose were significantly reversed by adding either myo-inositol or AL1576, an aldose reductase inhibitor (ARI). However, the addition of neither myo-inositol nor ARI stimulated IP3 formation and/or DNA synthesis when BRCP were grown in the standard medium (5 mM glucose). These findings indicate that myo-inositol metabolism and the polyol pathway affect inositol phospholipid-mediated pericyte division in vitro only under the high-glucose condition. These data are compatible with the hypothesis that altered inositol phospholipid metabolism accounts for the loss of pericytes in diabetic retinopathy.

Animals↗