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Biomedical subjects

X M Li

Publications and source records attributed to X M Li.

At least 199 records · Page 11Linked to original sources
PubMed1989

The influence of ovarian hormones on the rat oviductal and uterine concentration of noradrenaline and 5-hydroxytryptamine.

This paper describes the effects of estradiol and progesterone on the concentrations of noradrenaline and 5-hydroxytryptamine in the Wistar rat oviduct and uterus. The levels of noradrenaline and 5-hydroxytryptamine are higher in the oviduct than in the uterus whereas p-tyrosine and tryptophan are similar in both tissues. Estradiol treatment reduced the oviductal concentration of noradrenaline but not 5-hydroxytryptamine in oviduct, while the concentrations of both noradrenaline and 5-hydroxytryptamine were reduced in uterine horn. The levels of noradrenaline in the oviduct and uterus in rats in estrus were lower than those of diestrous rats. Bilateral ovariectomy produced an increase in uterine noradrenaline and 5-hydroxytryptamine levels. These changes were reversed in the presence of ovarian hormone as indicated by experiments where unilateral ovariectomy was performed. Reserpine administration reduced noradrenaline concentration in both the oviduct and the uterus but did not change oviductal or uterine 5-hydroxytryptamine. These results indicate the existence of noradrenaline within postganglionic sympathetic nerve terminals and suggest that estrogens increase the utilization and the synthesis of noradrenaline in both the oviducts and the uterine horns. With respect to 5-hydroxytryptamine the data support the concept that it is mainly associated with mast cells.

Animals↗
PubMed1989

[Component analysis of the extracellular polysaccharide from Mortierella hepiali Chen et Lu sp. nov].

The extracellular polysaccharide from the filtrate of fungal fermentation of Mortierella hepiali, a fungus isolated from traditional Chinese crude drug Cordyceps sinesis, is made up of three sugar components, glucose, mannose and galactose, which are detected by paper and gas chromatography. Both molar ratio and contents of the polysaccharide are determined by the internal standard method.

Animals↗
PubMed1989

[The effects of moxibustion at "zusanli" point on serum endocrine hormones of rats].

The effects of moxibustion at "Zusanli" acupoint on serum endocrine hormones of male Wistar rats were studied by measured serum values of TSH, T3, T4, FSH, LH, testosterone and insulin with radioimmunoassay, 40 male rats were randomly divided into two groups, experiment group and control group, 20 rats each group. In the experiment group, the animals were given a moxibustion at "Zusanli" acupoints of both sides of rats 8:00-9:00 am, 10 min/side per day for 7 days. The control group was given nothing. All of both groups were killed and got serum at same time. The results indicate that the moxibustion can increase significantly serum value of insulin (p less than 0.01) and decrease prominently serum value of T4 (p less than 0.01), but no marked difference was found in FSH, LH, testosterone, TSH and T3. It is suggest that the raise of insulin may have relations with the effects of the moxibustion on neuro-endocrine system and improving microcirculation of pancreas gland, and that the drop of T4 may be caused by the moxibustion to inhibit the function of thyroid gland.

Acupuncture Points↗
PubMed1989

[Carcinogenicity and organic fraction of indoor inhalable particles].

The inhalable particles in high and low incidence area of lung cancer in Xuanwei country were extracted with dichloromethane. The extract was separated into aliphatics, PAH, N-PAH, H-PAH, polar compounds by neutral aluminum oxide column chromatography. Mutagenicity and carcinogenicity of different fraction were studied in the Ames test and Two-stage skin carcinogenesis test. The results suggested that the indoor air pollutants in high incidence area showed higher carcinogenicity, higher percentage of PAH fraction and methylated PAH. Ames test showed PAH, N-PAH, H-PAH were active fractions, the N-PAH fraction has maximal mutagenicity. Two-stage skin carcinogenesis test showed the PAH fraction has the highest carcinogenicity, followed by the N-PAH fraction. The results indicated the main carcinogenic fraction and carcinogens of indoor air pollutions in high incidence area of lung cancer in Xuanwei country.

Air Pollution↗
PubMed1989

Treatment of childhood anorexia with spleen deficiency by Qiang Zhuang Ling.

The authors' traditional Chinese herbal prescription, Qiang Zhuang Ling, was used to treat childhood anorexia with Spleen deficiency. For comparison, a group of cases treated by zinc sulphate solution was also set up as controls. After a course of treatment, the therapeutic effect in the Qiang Zhuang Ling group was significantly better than in the zinc sulphate group. Furthermore, in both groups, the level of hair zinc were markedly increased; the ultrastructure of hair was recovered; and the activity of macrophages was enhanced.

Anorexia↗
PubMed1988

Monoclonal antibodies that inhibit activation of transcription by the Escherichia coli cyclic AMP receptor protein.

The properties of the two monoclonal antibodies which were found to inhibit cyclic AMP receptor protein (CRP)-stimulated abortive initiation without affecting cAMP binding (Li, X.-M., and Krakow, J. S. (1986) J. Biol. Chem. 260, 4378-4383) have been characterized. Binding of monoclonal antibody (mAb) 66C3 to CRP is stimulated by cAMP while CRP binding by mAb 63B2 is not affected by cAMP. Binding of cAMP-CRP-mAb 63B2 to the lac P+ DNA is completely inhibited. Whereas cAMP-CRP forms a stable complex only at the CRP site 1 of the lac P+ promoter fragment, cAMP-CRP-mAb 66C3 binds to both site 1 and site 2. DNase I footprinting using a HpaII fragment carrying only the lac site 2 does not show any protection by cAMP-CRP-mAb 66C3. With the lac L8UV5 promoter, binding is not seen at either the L8 site 1 or the unaltered site 2. In the presence of 25% glycerol, cAMP-CRP-mAb 66C3 binds to both L8 site 1 and site 2. RNA polymerase is unable to bind to the cAMP-CRP-mAb 66C3-lac P+ complex. In the presence of RNA polymerase, cAMP-CRP forms a stable complex at the L8 site 1, the subsequent addition of mAb 66C3 results in the release of CRP. The CRP present in the lac P+ open promoter complex is partially resistant to subsequent incubation with mAb 66C3. The results provide further evidence regarding possible contacts between CRP and RNA polymerase involved in establishing the open promoter complex.

Antibodies, Monoclonal↗
PubMed1988

An integrated microcomputer system using immobilized cellular electrodes for drug screening.

Biosensors based on immobilized microbial cells were developed for drug screening in our laboratory. Compared with the conventional methods such as diffusion and dilution tests, biosensors have been demonstrated to be superior in sensitivity and require much shorter screening time. An integrated microcomputer system has been developed for data acquisition, database management, and mode of action estimation, which automates the screening processes and reduces the labor requirements significantly.

Anti-Bacterial Agents↗
PubMed1987

A monoclonal antibody that inhibits cyclic AMP binding by the Escherichia coli cyclic AMP receptor protein.

The monoclonal antibody (mAb) 64D1 was found to inhibit cAMP binding by the cAMP receptor protein (CRP) from Escherichia coli (Li, X.-M., and Krakow, J. S. (1985) J. Biol. Chem. 260, 4378-4383). CRP is relatively resistant to attack by the Staphylococcus aureus V8 protease, chymotrypsin, trypsin, and subtilisin whereas both mAb 64D1-CRP and cAMP-CRP are attacked by these proteases yielding N-terminal core fragments. The fragment patterns resulting from proteolysis of mAb 64D1-CRP and cAMP-CRP differ indicating that the CRP in each complex is in a different conformation. The data presented indicate that the preferred conformation of the antigenic site for mAb 64D1 is present in unliganded CRP. Binding of mAb 64D1 to CRP is inhibited at high cAMP concentration. Formation of a stable cAMP-CRP-lac P+-RNA polymerase open promoter complex resistant to dissociation by mAb 64D1 occurs at a much lower cAMP concentration. The observed increase in resistance to mAb 64D1 may reflect a possible conformational change in CRP effected by contact with RNA polymerase in the open promoter complex.

Antibodies, Monoclonal↗
PubMed1987

Lung cancer and indoor air pollution in Xuan Wei, China.

In Xuan Wei County, Yunnan Province, lung cancer mortality is among China's highest and, especially in females, is more closely associated with indoor burning of "smoky" coal, as opposed to wood or "smokeless" coal, than with tobacco smoking. Indoor air samples were collected during the burning of all three fuels. In contrast to wood and smokeless coal emissions, smoky coal emission has high concentrations of submicron particles containing mutagenic organics, especially in aromatic and polar fractions. These studies suggested an etiologic link between domestic smoky coal burning and lung cancer in Xuan Wei.

China↗
PubMed1985

Structure of an antifreeze polypeptide and its precursor from the ocean pout, Macrozoarces americanus.

Serum antifreeze polypeptides (AFP) from Newfoundland ocean pout have been resolved by ion exchange chromatography and reverse phase high performance liquid chromatography into at least 12 components. The protein sequences of three of the AFP were determined using a combination of protein Edman degradation and cDNA sequencing. The AFP precursor protein encodes for a preprotein of 87 amino acids with no obvious prosequences. Two of the AFP (SP1-A and SP1-C) were separate gene products with minor amino acid sequence differences. The protein structure of SP1-C precursor is MKSVILTGLLFVLLCVDHMTASQSVVAT QLIPINTALTPAMMEGKVTNPIGIPFAEMSQIVGKQVNTPVAKGQTLMPNMVKTYVAGK. The third AFP (SP1-B) is a post-translation modification product of SP1-C. These experiments indicate that the ocean pout AFP are a multigene family with protein structure different from any other known polypeptide antifreezes.

Amino Acid Sequence↗