Biomedical subjects
Publications and source records attributed to X Yang.
The essential oils of roots and fruits of five species of Angelica have been examined and analysed by GC-MS-DS; 59 chemical compounds are reported, of which alpha-pinene, myrcene and p-cymene are common to all five species. This paper provides a scientific basis for developing the resources of this genus in the Northeast.
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The specimen of the total saponin for this experimental study was extracted from Gynostemma pentaphylla growing in Suining county in Hunan province. Weight of immune organs, content of anti-SRBC hemolysin, rate of special Ea-RFC formation and percentage of NK cell activity had been employed for the study as experimental indices, both the normal healthy mice and the mice with immunity impairment due to Cyclophosphamide (Cy) management as experimental models. The results of the study exhibited: (1) The total saponin of Gynostemma pentaphylla could markedly act against the immunity inhibition due to Cy management in the experimental animals, showing a variant recovery in mice treated by Cy in weight of the immune organs, content of hemolysin, forming rate of Ea-RFC and unequivocally elevating NK cell activity, by significant difference in comparison with the Cy control groups (P less than 0.05-0.01). (2) The total saponin showed a definite of bidirective immunomodulatory action in normal healthy mice, recovering the immune indices to normal value from either originally lower or higher than the medium figure, by significant difference in comparison with the Cy control groups (P less than 0.05-0.01). (3) The total saponin had actions to prevent from fatigue and to tolerate hypoxia under usual atmospheric pressure. The above description indicates that the total saponin of Gynostemma pentaphylla is a better immunomodulator, seems to be like the actions of some Chinese drugs, for example, Panax ginseng, Astragalus membranaceus etc.
Mosquito-nets were sprayed with 9.6mg deltamethrin per square meter for control of malaria vectors in Yibin County, Sichuan Province in 1986. In the study area, the relative population indices of Anopheles anthropophagus and An. sinensis in 35 mosquito-nets were 0.6 and 1.4 respectively; the man biting rates of these two vectors dropped by 97.8 and 90.8% respectively. The residual toxic effect of sprayed mosquito-nets, up to 104 days after spray, caused a mortality of 93.1-100% of An. anthropophagus and 87.1-100% of An. sinensis. The multiparous mosquito rate dropped by 48.4 and 51.3%. Indoor-intruding An. anthropophagus and An. sinensis were reduced by 76% and 78.3% respectively. The incidence of malaria decreased by 94.4%, the positive rate in school children declined by 77.5%. Both entomological and epidemiological indices indicated that mosquito-nets sprayed with deltamethrin could effectively control the malaria prevalence. This measure is economical and practical for control of malaria.
Models of rats with iron deficiency anemia (IDA) were established, and changes in development of the thymus and spleen and adenosine deaminase (ADA) activity in them studied. The size and weight of the thymus in IDA rats were decreased, which suggested that the development of the thymus was lowered; but the size and weight of the spleen in IDA group were increased. ADA activities of the thymus and the spleen in IDA rats were significantly decreased by 32.98% and 25.89%, respectively. One week after iron supplement, the weight of the thymus and spleen in IDS group returned to normal level (P greater than 0.05), and their ADA activity also significantly increased, but ADA activity of the thymus tissue did not return to the normal. The results suggested that the changes in ADA activity of the thymus and spleen tissues were related to iron deficiency. Stepwise regression analysis suggested that there was a negative correlation between ADA activity of the thymus tissue and FEP/Hb ratio.
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The molecular structures of phosphorylase b and phosphorylase kinase have been visualized by scanning tunneling microscopy (STM). STM is a near field technique that can resolve structures at the nanometer level and thus can image individual molecules. Phosphorylase b can be seen in dimeric and tetrameric forms as well as linear and globular aggregates. The linear arrays consist of side by side dimers with the long axis of the dimer perpendicular to the aggregated chain. Individual molecules of phosphorylase kinase appear to be planar, bilobate structures with a 2-fold axis of symmetry and a central depression.
Some reports indicate that sperm from different males differ in capacitation time, and other reports suggest that freezing sperm may affect their capacitation time. These two variables were specifically studied in rabbits in a fertility trial with 96 does inseminated with approximately 1.6 million motile fresh or frozen sperm from three different bucks at 15, 10, 5, and 0 h before expected ovulation. Fresh semen averaged 84% live (unstained) sperm and 88% had normal acrosomes; corresponding values for frozen sperm were 44% and 54%. On the basis of does that became pregnant, average litter size with fresh semen was 5.5 and with frozen semen was 4.8 (p greater than 0.05), but overall, does bred with frozen semen produced fewer young (p less than 0.05). On the basis of total does and total semen, average litter size from insemination at 15, 10, 5, and 0 h was 2.8, 4.2, 3.8, and 1.7, and average litter size for the three bucks was 4.0, 1.8, and 3.6. There was no interaction of type of semen (fresh or frozen) with the other variables in the model (p greater than 0.05). Bucks and time of insemination affected both the proportion of does that were pregnant and litter size (p less than 0.01). A major interaction between buck and time of insemination (p less than 0.01) was due apparently to both differential sperm survival and probable capacitation time among bucks. This major interaction should be considered in designing in vitro and in vivo fertility studies, and for selecting males for use in artificial insemination.
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Eighteen species of fishes were collected during the open water (1985-1987) and winter seasons (1985-1986) from Dauphin Lake, Manitoba, Canada (51 degrees 17'N, 99 degrees 48'W) and examined for plerocercoids of Ligula intestinalis (L.). Plerocercoids were most prevalent (5.3%) in spottail shiners (Notropis hudsonius), the major fish host for Ligula in Dauphin Lake. Detailed analysis of the spottail shiner-Ligula host-parasite system revealed that the number of plerocercoids differed between years and among habitats but there was no statistically significant seasonal pattern; recruitment of new worms was highest in young fish and decreased with age, and infected spottails had reduced gonad development. Analysis of host and parasite growth revealed that the soma of male spottails infected with Ligula weighed more but had a reduced growth rate. Growth rate of females was unaffected by Ligula but somatic weight was slightly increased. This appears to be related to the greater metabolic stress on infected males. Based on increased mean somatic weight and skewness of the weight distribution for infected fish, we propose that infected spottails are subjected to size-selective mortality. Some of the contradictions in the literature may be attributed to underestimated prevalence due to increased numbers of spawning fish in the spring, mixed age-classes of Ligula in separate age-classes of fish, and differential effects on growth due to infection in male versus female hosts.
The purpose of the present study was to investigate the effect of tyrosine on progesterone and hCG production by human placental cells in vitro. The results showed that the three concentrations (0.02 mmol/L, 0.2 mmol/L and 2mmol/L) of tyrosine inhibited progesterone secretion by trophoblast cells in vitro. While progesterone secretion was suppressed by tyrosine, hCG secretion was unchanged. Thus, it seems unlikely that the suppression of progesterone production by tyrosine was due to a decrease in hCG production. It was further demonstrated that tyrosine inhibited 3 beta-HSD activity of trophoblast cells, indicating that the progesterone production inhibition by them might be due to the decreased 3 beta-HSD activity of trophoblast cells.
Isoelectrofocusing technique was used to study the inhibiting effect of 14 insecticides on esterase isozymes of Culex tritaeniorhynchus from natural populations in Fuzhou, Shanghai, Qingdao, Dalian and Beijing areas. Among 14 insecticides, organophosphates were good inhibitors to all esterase isozymes, but Allethrin, Propoxur, DDT, Dieldrin had no or almost no inhibiting effect on esterase. 26 esterase isozyme bands of Culex tritaeniorhynchus were revealed by isoelectrofocusing.
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The HeI UV photoelectron spectrum of trimethyl phosphate (TMP) has been measured and interpreted with the aid of SCF molecular orbital calculations carried out with STO-3G, STO-3G* and 4-31G basis functions. The photoelectron spectrum of TMP is more accurately reproduced by results from 4-31G calculations than by results from STO-3G or STO-3G* calculations. However, all three basis sets yield results which predict the same assignment of the photoelectron spectrum. Results at the 4-31G level indicate that whether calculations are based on crystallographic bond angles and bond lengths or on STO-3G optimized geometries has little effect on the energetic ordering of the upper occupied orbitals. The energetic ordering of orbitals is also found to be only weakly dependent upon the torsional angle phi, describing rotation of ester groups about P-O bonds and upon the torsional angle psi, describing rotation of methyl groups about C-O bonds. For trimethyl phosphate, with C3 symmetry, the vertical ionization potentials of the upper occupied orbitals are 10.81 eV (8e), 11.4 eV (9a), 11.93 eV (7e), 12.6-12.9 eV (8a and 6e), 14.4 eV (7a) and 15.0-16.0 eV (5e and 6a). Calculations at the 4-31G level indicate that many of the highest occupied orbitals in neutral dimethyl phosphate and methyl phosphate have energies and electron distributions similar to orbitals in TMP. For TMP, a search for optimized values of phi and psi has been carried out at the STO-3G*level. In agreement with previous NMR studies and with classical potential calculations, the STO-3G* results indicate that both the gauche (phi = 53.1 degrees) and anticlinal (phi = 141.9 degrees) conformations are thermally accessible. Also in agreement with the classical potential calculations, the STO-3G* results predict that in the all gauche conformation energy is minimized when the methyl groups assume a staggered geometry (psi = 60 degrees to 80 degrees) and that an energy maximum occurs for an eclipsed geometry (phi = 0 degrees to 20 degrees). A study of the dependence of optimized values of O-P-O ester bond angles on the torsional angles, phi, was carried out at the STO-3G, STO-3G* and 4-31G levels. The results demonstrate that for C3 symmetry, the coupling of O-P-O angles to phi is influence by repulsive steric interactions.
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