[Effect of alcohol extracts of Chrysanthemum morifolium on Plasmodium falciparum in vitro].
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Animals↗
Biomedical subjects
Y Lei
Publications and source records attributed to Y Lei.
IT-143-A and B, novel piericidin-group antibiotics produced by Streptomyces sp.
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Anti-Bacterial Agents↗
[Effect of yuxintong capsule on plasma endothelin and serum nitric oxide in acute myocardial ischemia dogs].
Effect of Yuxintong (YXT) capsule on plasma endothelin(ET), serum nitric oxide (NO) and creatine phosphokinase (CPK) activity in experimental acute myocardial ischemia dogs were observed. The results indicated that in acute myocardial ischemia dogs, the serum CPK activity and plasma ET level increased and serum NO level decreased significantly. In comparing with control, YXT not only could reduce significantly the increased plasma ET content and serum CPK activity, but also increase markedly the producing and releasing of NO, P < 0.05-0.001. Therefore, it could protect the myocardia from ischemic damage, the efficacy of YXT was positively dose dependent.
Animals↗
[Observation on TXB2 and 6-keto-PGF1 alpha in serum of patients with cor pulmonale].
To know the changes of TXA2 and PGI2 in serum of patients with cor pulmonale, the levels of their stable metabolites TXB2 and 6-keto-PGF1 alpha in serum were examined in 28 patients with cor pulmonale during alleviation, 29 patients with cor pulmonale during exacerbation before and after treatment and 10 healthy subjects. TXB2 and 6-keto-PGF1 alpha were 109.74 +/- 56.14 ng/L and 54.76 +/- 35.62 ng/L respectively in healthy subjects; TXB2/6-keto-PGF1 alpha = 2.004. The TXB2 level of patients with cor pulmonale at every stage was higher than that of healthy subjects (P < 0.05-0.01). Patients with cor pulmonale during exacerbation had the highest TXB2 level of 709.22 +/- 354.49 ng/L, which decreased to 408.24 +/- 289.41 ng/L (P < 0.05) after treatment with traditional Chinese medicine combined with western medicine and the decreased level as such was not significantly different from that during alleviation (333.14 +/- 324.14 ng/L). The 6-keto-PGF1 alpha level in patients with cor pulmonale at every stage was not significantly different from that of healthy subjects. Since TXB2 increased, the value TXB2/6-keto-PGF1 alpha of patients with cor pulmonale was greater than that of healthy subjects. It is most likely that chronic hypoxia and hypercapnia lead to prostaglandin release in the lung of patients with cor pulmonale; hypoxia and hypercapnia become more severe during exacerbation resulting from infection; which lead to increased prostaglandin release, then high TXB2 level ensue as the result. TXB2 decreases after amelioration of hypoxia during treatment. But the change of 6-keto-PGF1 alpha is not obvious.
6-Ketoprostaglandin F1 alpha↗
Expression of genes associated with antibiotic extrusion in Pseudomonas aeruginosa.
We cloned the gene(s) associated with multiantibiotic resistance in Pseudomonas aeruginosa from a mutant with elevated drug extrusion. The strain harboring cloned gene accumulated less amount of ofloxacin than the strain without the clone. By using Southern and northern blot analyses, we investigated whether multiantibiotic resistance is caused by gene amplification or overexpression. We found that all our multiantibiotic resistance is caused by gene amplification or overexpression. We found that all our multiantibiotic resistant mutants isolated earlier overexpressed mRNA homologous to the cloned gene(s). Overexpression of the 41 KDa and 110 KDa inner and the 50 KDa outer membrane proteins were detected. Other multiantibiotic resistant mutants including the nalB mutant overexpressed the mRNA and the membrane proteins, but the nfxB and nfxC mutants did little. We concluded that low antibiotic accumulation in the multiantibiotic resistant mutants is attributable to overexpression of the antibiotic extrusion machinery.
Cloning, Molecular↗
Mechanistic studies on CDP-6-deoxy-L-threo-D-glycero-4-hexulose 3-dehydrase identification of His-220 as the active-site base by chemical modification and site-directed mutagenesis.
CDP-6-deoxy-L-threo-D-glycero-4-hexulose 3-dehydrase (E1) purified from Yersinia pseudotuberculosis is a pyridoxamine 5'-phosphate (PMP) dependent iron-sulfur-containing enzyme which catalyzes the C-O bond cleavage at C-3 of its substrate leading to the formation of 3,6-dideoxyhexose. This enzyme is rapidly inactivated by diethyl pyrocarbonate (DEP) at pH 6.0 and 25 degrees C. The inactivation of E1 by DEP, which is reversible upon treatment of hydroxylamine, appears to be attributable solely to the modification of histidine residues. The fact that coincubation of E1 with its substrate gave almost total protection against DEP inactivation and that only one less histidine residue was modified in the presence of substrate strongly suggested that inactivation is due to the modification of only one reactive histidine residue which resides in or near the active site of E1 and is critical for E1's activity. Sequence alignment between the translated ascC (E1) gene and several representative pyridoxal 5'-phosphate (PLP)/PMP dependent enzymes revealed that three of the four invariant residues, glycine, aspartate, and arginine found in all other aminotransferases, are conserved in the E1 sequence (G169, D191, and R403). However, the highly conserved lysine is replaced by a histidine residue (H220) in E1. In order to test whether H220 plays an essential role in E1 catalysis, H220N mutant was constructed and the encoding protein was found to exhibit nearly identical physical characteristics as the wild-type E1. Interestingly, the mutant protein had lost most of its catalytic activity, and one less histidine residue was modified upon treatment of H220N-mutated protein with DEP. Such a single-point mutation also impaired E1's capability of catalyzing the solvent hydrogen exchange at C-4' position of the PMP coenzyme. Our findings strongly suggested that H220 is most likely the active-site base which abstracts the C-4' proton from the PMP-substrate adduct and initiates the catalysis. Furthermore, E1's preservation of other invariant residues found in many PLP/PMP dependent enzymes allowed a speculation of their roles in E1 catalysis.(ABSTRACT TRUNCATED AT 400 WORDS)
Amino Acid Sequence↗
Mechanistic studies on CDP-6-deoxy-delta 3,4-glucoseen reductase: the role of cysteine residues in catalysis as probed by chemical modification and site-directed mutagenesis.
CDP-6-deoxy-delta 3,4-glucoseen reductase (E3), which catalyzes the reduction of the C-3 deoxygenation step during the formation of CDP-ascarylose, a 3,6-dideoxyhexose found in the lipopolysaccharide of Yersinia pseudotuberculosis, has been expressed at high level in Escherichia coli (670 times over the wild-type strain). This flavoenzyme, which also contains one plant ferredoxin type [2Fe-2S] cluster, was inactivated by 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and N-ethylmaleimide. In both cases the inactivation followed a pseudo first order kinetics. The second order rate constant for the reaction of DTNB with E3 was 0.25 mM-1 min-1 at 20 degrees C, pH 8.0. Detailed characterization of the inactivated enzyme showed that neither the flavin nor the [2Fe-2S] cluster was altered during inactivation. Since this inactivation was reversible by treating the inactivated enzyme with 1 mM D,L-dithiothreitol (DTT), it was concluded that only cysteine residues were modified during inactivation. Analysis of the inactivation using the method developed by Tsou revealed that two cysteines react with DTNB at similar rates and modification of either one is enough to impair E3's activity. Tryptic digestion of E3 labeled with N-ethyl[2,3-14C]maleimide, followed by fractionation of the digest by high performance liquid chromatography, gave two labeled peptides, both of which were separately isolated as a pair of interconvertible diastereoisomers. Sequence analysis of these labeled peptides allowed the identification of Cys-75 and Cys-296 as the reactive cysteine residues. Interestingly, the C75S and C296S mutant proteins exhibit identical physical and comparable catalytic properties as the wild-type enzyme. Since Cys-296 is a conserved residue in the NAD(P) binding domain of enzymes belonging to the same class, this residue may be involved in stabilizing the charge-transfer complex between E3 and NADH, thus facilitating hydride transfer from the nicotinamide nucleotide to flavin. A chemically modified Cys-75 which is immediately adjacent to the [2Fe-2S] center in E3 may prevent the proper juxtaposition of the redox centers and thus impede electron transfer leading to enzyme inactivation. These results may be useful for placing constraints on the peptide folding comprising the active site of E3 for electron transfer between NADH, FAD, and the [2Fe-2S] center.
Amino Acid Sequence↗
[An in vivo study on DNA-protein crosslinks induced by nickel chloride].
DNA-protein crosslinks (DPC) in the white blood cells (WBC) and lung tissues were detected with a new and sensitive 125I-post-labelling technique in male Sprague-Dawley rats injected peritoneally (i.p.) with nickel chloride (NiCl2). Results showed DPC in the WBC and lungs of the rats increased significantly 20 hours after acute exposure to NiCl2. Multiple small doses (10 mg/kg i.p., twice a week for three weeks) of NiCl2 had similar effects as single large dose (30 mg/kg). It suggested DPC could be used as a biomarker to reflect genotoxicity to the WBC and lungs caused by nickel compound. DPC in the WBC increased more obviously than that in the lungs after exposure to NiCl2, and both correlated to each other. It showed DPC in the WBC can be used as a surrogate to indicate genotoxic lesions in target organs.
Animals↗
[Cell-mediated immune function in NPC patients treated with cimetidine].
Cimetidine (CMD), an H2 receptor antagonist, was used in combination with radiation for the treatment of patirnts with nasopharyngeal cancer (NPC). In patients treated with radiotherapy alone, there was an increase in the number of CD4+ T cells and in NK cell activity. In patients received combined treatment of radiation and CMD, in addition, there was a decrease in CD8+ T cells with an increase in CD4/CD8 ratio and an increase in IL-2 production. The NK cell activity was also stronger in the latter group. The results suggest that CMD helps restore cell-mediated immunity in NPC patients radiation treated.
Adjuvants, Immunologic↗
[Study on the optimums for Pseudomonas maltophilia HCG receptor expression].
According to the design of orthogonal experiment, the optimums for expression of Pseudomonas maltophilia with HCG receptor were studied by radioassay. The results showed that the optimums influencing the specific binding percentage of Pseudomonas maltophilia were the cultures of No. 3 solid medium added with 0.5% galactose and incubated at a temperature of 37 C for 72 hours. Under these conditions, the binding percentage of Pseudomonas maltophilia to HCG was higher than those under other conditions.
Pseudomonas↗
Serological survey of nasopharyngeal carcinoma in 21 cities of south China.
This paper reports the results of serological survey of 318,912 persons for nasopharyngeal carcinoma (NPC) in 21 cities and counties of south China. There were 8,441 persons with positive VCA-IgA antibody (single item positive) of EB virus (EBV), with a rate of 2.65%. In these VCA-IgA positive persons, 287 persons also had positive EA-IgA (double items positive) of EBV. The overall positive rate was 0.09%. 100 cases of NPC were found and 87 of them (87.0%) were in early stage. NPC found in the group with single item positive accounts for 1.19%, but the rate in the group with double items positive was 19.16% (55 cases). In NPC patients with double items positive, 49 cases were in early stage (89.1%). In 100 cases of NPC found, 45 cases appeared with negative EA-IgA, only with positive VCA-IgA, which indicated that for diagnosis of NPC, sensitivity of EA-IgA was lower than that of VCA-IgA, but its specificity was higher. Therefore, both can increase the detecting rate and early diagnosis rate of NPC. The age of people checked varied with different antibody positive rate and NPC detecting rate. The three items showed a positive correlation. The results are compatible with those of the prospective study for NPC in Wuzhou City, Guangxi, China. The method for NPC serological diagnosis can be extended and applied to raise the NPC detecting rate and early diagnosis rate at secondary prevention. And, it is further proved that there is a close relationship between NPC and EBV.
Adult↗
CDP-6-deoxy-delta 3,4-glucoseen reductase from Yersinia pseudotuberculosis: enzyme purification and characterization of the cloned gene.
The 3,6-dideoxyhexoses, usually confined to the cell wall lipopolysaccharide of gram-negative bacteria, are essential to serological specificity and are formed via a complex biosynthetic pathway beginning with CDP-D-hexoses. In particular, the biosynthesis of CDP-ascarylose, one of the naturally occurring 3,6-dideoxyhexoses, consists of five enzymatic steps, with CDP-6-deoxy-delta 3,4-glucoseen reductase (E3) participating as the key enzyme in this catalysis. This enzyme has been previously purified from Yersinia pseudotuberculosis by an unusual procedure (protocol I) including a trypsin digestion step (O. Han, V.P. Miller, and H.-W. Liu, J. Biol. Chem. 265:8033-8041, 1990). However, the cloned gene showed disparity with the expected gene characteristics, and upon expression, the resulting gene product exhibited no E3 activity. These findings strongly suggested that the protein isolated by protocol I may have been misidentified as E3. A reinvestigation of the purification protocol produced a new and improved procedure (protocol II) consisting of DEAE-Sephacel, phenyl-Sepharose, Cibacron blue A, and Sephadex G-100 chromatography, which efficiently yielded a new homogeneous enzyme composed of a single polypeptide with a molecular weight of 39,000. This highly purified protein had a specific activity nearly 8,000-fold higher than that of cell lysates, and more importantly, the corresponding gene (ascD) was found to be part of the ascarylose biosynthetic cluster. Presented are the identification and confirmation of the E3 gene through cloning and overexpression and the culminating purification and unambiguous assignment of homogeneous E3. The nucleotide and translated amino acid sequences of the genuine E3 are also presented.
Amino Acid Sequence↗
[Studies on the mechanism of Polyactin A's enhancive effect on NK cell activity].
It has been shown that the novel immunopotentiator Polyactin A (PAA) developed in China can augment NK cell activity. In order to further understand the mechanism of PAA effect on NK activities, we measured the binding and lytic capacities of peripheral blood lymphocytes (PBL) isolated from normal subjects and patients with esophageal carcinoma against K562 target cells by using a single cell cytotoxicity assay. Morphologically the ultrastructures of NK cells of normal subjects and the patients on PAA were also studied. The results showed that: (1) Preincubation PBL of normal subjects on PAA at 100 micrograms/ml for 4 hours could increase the rate of NK lysis with no effect on the binding rate. The binding capacities of PBL of patients with esophageal carcinoma were lower than those of normal subjects. Pretreatment PBL of patients with esophageal carcinoma could significantly increase not only the rate of NK lysis, but also the binding rate. (2) Study on the processes of conjugation and cytolysis by using light microscopic morphology, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) found that effector cells include not only large granular lymphocytes (LGL), but also non-LGL bound to target cells. One effector cell could simultaneously make contacts with more than one target cell. It was found that PBL/K562 contacts could be morphologically divided into two types in the SEM and TEM. Either effector cell protrusions were pushed deep into pouches and lacunae of the target cell surface or a wide area of intimate cell-to-cell contact was formed. Effector/target cell contact is a prerequisite for NK lytic activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Further characterization of endometrial integrins during the menstrual cycle and in pregnancy.
OBJECTIVE: To profile the changes in integrin expression in cycling and pregnant endometrium. DESIGN: Immunohistochemistry was performed on endometrium from proliferative, early, and midsecretory phase and early pregnancy using a blinded panel of monoclonal antibodies directed against integrins. Closer examination of the cycle-dependent integrins was performed in 112 patients throughout the cycle and from the first trimester of pregnancy. SETTING: An academic teaching hospital. PATIENTS: Ovulatory women or women undergoing pregnancy termination. MAIN OUTCOME MEASURE: Staining intensity of each antibody in epithelial or stromal cells. RESULTS: Certain integrins were present constitutively throughout the menstrual cycle whereas others were expressed only during the luteal phase. Four integrins increased in the decidua of pregnancy. The timing of expression of the two cycle-dependent integrins (alpha 4 beta 1 and alpha v beta 3) framed the putative window of implantation and suggests a role in establishment of uterine receptivity. CONCLUSIONS: Our findings confirm the patterns of endometrial integrins and suggest important roles for integrins in the process of implantation and decidualization.
Antibodies, Monoclonal↗
Exon skipping gives rise to alternatively spliced forms of the estrogen receptor in breast tumor cells.
We have previously described three messenger RNA variants coding for the human estrogen receptor (ER) [1]. These variants were identified using the polymerase chain reaction to perform directed cloning of ER cDNAs synthesized from polyadenylated RNA extracted from the human breast cancer cell line T47D. Each of the variants is characterized by the precise deletion of a single exon within the protein coding region of this message and was presumably derived by inaccurate or promiscuous splicing of primary estrogen receptor transcripts. We report here the results of RNAse protection experiments which independently confirm the existence of these splicing variants in T47D cells. Similar analysis of RNA from MCF-7 cells also revealed the presence of variant ER transcripts, suggesting that they may be a common finding in tumor cell lines which express the estrogen receptor. However, attempts to identify splicing variants in a number of nominally ER-negative cell lines using either RNAse protection or PCR amplification were without success.
Breast Neoplasms↗
[Studies on preparation technology of microspheres of contraceptives].
Contraceptive poly ethylglycol-lactide (PEGL), an artificial biodegradable polymer microsphere was prepared by a solvent evaporation process using levonorgestrel (LNG) and estradiol (E2) as model drugs and PEGL as the core material. The experimental conditions were optimized, the mean volume diameter obtained being 30 microns and rate of encapsulation 75-82%. In vitro, it was found that the drug release rate decreased with decreasing drug content in the microspheres. The microspheres of the contraceptive maintained anticonception duration in mice for over 6 months, indicating that the microspheres have remarkably long acting sustained release action.
Animals↗
[Study on 125I-labeled human chorinic gonadotropin after purification through gel electrophoresis].
Radioiodination of HCG with 125I Na using chloramine-T is widely employed. However, 125I-HCG damages in storage and thus results in decrease of immunological and biological activities. When 125I-HCG was in store as long as 30 days, the immunological activity and biological activity decreased from 100% to 33.1% and 44.0%, respectively. We used polyacrylamide gel electrophoresis to purify 125I-HCG which had been kept in store for 30 days since radiolabeling, and we found the binding capacities of purified 125I-HCG increased. The combination rates of purified 125I-HCG with antibody and receptors accounted for 90.5% and 95.3% of those of 125I-HCG 1 day after radiolabeling. These results suggest that 125I-HCG which has been stored for a period since radiolabeling should be purified before use.
Chorionic Gonadotropin↗
[Therapeutic effects of Chinese drugs on early renal damage of rats caused by fish bile].
The therapeutic effects of Salvia miltiorrhizae, Typha angustifolia, Rheum palmatum preparations on early renal damage of rats caused by fish bile were observed. These drugs were effective in reducing serum creatinine, urinary NAGase, count of necrosed epithelial cells of proximal tubule and that of glomerular filled with RBC in Bowman's space (P < 0.05), and also effective in increasing creatinine clearance (P < 0.05).
Acetylglucosaminidase↗