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Biomedical subjects

L Ma

Publications and source records attributed to L Ma.

At least 271 records · Page 15Linked to original sources
PubMed1999

[Morphological cure of cerebral arteriovenous malformations by endovascular therapeutics].

OBJECTIVE: To sum up the clinical characteristics and typical manifestation by analysing clinical materials from total embolized cerebral arteriovenous malformations (AVM) via endovascular embolization. METHODS: We reviewed clinical and image materials of 50 patients whose cerebral AVM were embolized entirely and found the cerebral AVM morphological cure by endovascular embolization after studying the size, position, artery supply, therapeutics and follow-up. RESULTS: 50 patients with cerebral AVM were embolized by endovascular therapy, accounting for 17% of all patients. Malformation lesions were medium or small type, with a diameter less than 3 cm, 95% of them were located in the tentorium superior. Terminal end blood supply was common to AVM and especially medium cerebral artery (MCA) or its branches. 97% of the patients were graded III or below by spectzler grading system. 70% of them had a history of intracranial hemorrhage and were cured by one therapy. CONCLUSIONS: It is a reliable and feasible method for morphological cure in cerebral AVM via endovascular therapeutics only, but case selection is important, that is, medium or small AVM with single branch terminal end blood supply in the tentorium superior.

Adolescent↗
PubMed1999

[Identification on crude drugs from genus Leonurus: II. Leaf and flower surface characters].

OBJECTIVE: To identify the crude drugs originated from 9 species and 1 variety of genus Leonurus (called Yimucao) through leaf and flower surface characters. METHOD: Routine slide processing and the characters under microscope were observed and compared. RESULTS: Obvious characteristics for identification were revealed. CONCLUSION: The shape and length of non-glandular hairs are useful in identifying this sort of crude drugs. Leaf constants and cluster crystals are also useful as reference. However, pollen grains and secretory tissues are worthless.

Leonurus↗
PubMed1999

[Cerebral protective effects of some compounds isolated from traditional Chinese herbs].

OBJECTIVE: To study the cerebral protective effects of some compounds isolated from traditional Chinese herbs. METHOD: Laser microcirculation dynamic analyzer and cultured rat cortical neurons were used. RESULT: Pueraria lobata flavonoids(LPF), Panax notoginseng saponins(PNS), oxymatrine, anisodamine and berberine could dilate microvessels and increase the cerebral blood flow of anesthetized mice's meninges. LPF, PNS, oxymatrine, and anisodamine also accelerated the flow of blood. Oxymatrine, like anisodamine, increased quantities of erythrocytes in high frequency movements. PNS could protect cultured rat cortical neurons from glutamate neurotoxicity. CONCLUSION: LPF, PNS, oxymatrine, anisodamine and berberine have certain protective effects on brain, but differ in mechanisms of action.

Alkaloids↗
PubMed1999

[Advances in affinity chromatography].

This review is mainly concerned with the recent advances in (i) mechanism of affinity chromatography; (ii) the use of new techniques such as combinational chemistry, molecular imprinting, de novo design, fusion expression in discovery of ligand; (iii) improvement of support and chromatographic system; (iv) application of affinity chromatography. The review includes 66 references.

Biomimetics↗
PubMed1999

[Isotachophoresis analysis of hydrolytic products of DFP catalyzed by DFPase in porcine liver].

DFPase can hydrolyze the P-F bond of diisopropyl phosphate fluoride (DFP) to produce diisopropyl phosphate and HF. In this article, the activity of two kinds of DFPase from porcine liver was assayed by the methods of titration and F- ion sensitive electrode. The results showed that the activity of large molecular DFPase can be determined by both methods, but the activity of small molecular DFPase can only be determined by the titration and cannot be determined by F- ion sensitive electrode. The isotachophoresis analysis of the products of DFP hydrolyzed by the large and small molecular DFPase was studied. The results showed that the small molecular enzyme could catalyze the hydrolysis of DFP, but without the production of F- ion, and that this enzyme is one kind of phosphoesterase that hydrolyzed P-OR bond of DFP.

Animals↗
PubMed1999

[Determination of pericarpium papaveris(yingsuqiao) in bottom material of chafing dish by high performance liquid chromatography(HPLC)].

Morphine, codeine and papaverine in bottom material of chafing dish were determined by HPLC. The conditions were as follows: C18 column, mobile phase V(CH3OH):V(25 mmol/L KH2PO4) = 90:10, the flow rate 1 mL/min and the wavelength 254 nm. These three compounds were entirely separated. The blank and positive comtrasts were being done simultaneously. The detection limit was 0.1 mg/L. The experiment showed that this method is sensiuve, accurate and reliable.

Chromatography, High Pressure Liquid↗
PubMed1999

[The advances of the study on the optical chromatography].

This review is mainly concerned with the recent developments in (1) the differences between the optical tweezer and optical chromatography; (2) the principle of optical chromatography separation; (3) the theory studies on the optical chromatography, especially the relationship between the particle radius with the intensity of the applied laser radiation force and the relationship between the particle retention distance with the particle radius; (4) the application of the optical chromatography technique to the separation of polymers, biological macromolecules and biological cells. The application of optical chromatography to the immunoassy and molecular biology is highlighted.

Chromatography↗
PubMed1999

[Construction of a GFP broad-host-range promoter-probe vector and its application].

The 0.9 kb DNA fragment was obtained by PCR and using a pair of special designed primers from the green fluorescent protein gene(gfp). It Was then cloned into an expression vector pET-11C and named as pHN115. A promoferless gfp vector with SD fragment was obtained from pHN115 and subcloned into SK(+), pIJ 2925 and finally into pTR102. A broad-hast-range and visible promoter-probe vector, pHN127 was constructed and used successfully for the identification of constitutive and inducible promoters from Sinorhizobium fredii HN01.

Cloning, Molecular↗
PubMed1999

[Expression and identification of recombinant 22.6 kDa fusion protein of Schistosoma japonicum].

AIM: To obtain a large amount of purified 22.6 kDa antigen of Schistosoma japonicum (Sj22.6) in large quantity. METHODS: The sequence of the gene fragment encoding Sj22.6 was reformed by PCR and subcloned into plasmid vector pGEX-1 lambda T that coded for the 26 kDa GST antigen of Schistosoma japonicum (Sj26 GST). The recombinant plasmid was transformed into E. coli TG2 and then the positive recombinant clone was expressed by induction with IPTG. RESULTS: The recombinant Sj22.6/Sj26 GST fusion protein was expressed in 5.1% of total bacterial protein and was easy to be purified with glutathione sepharose 4B. Moreover, the purified recombinant Sj22.6 antigen could be cut off easily from the fusion protein with thrombin and had high immunogenicity. CONCLUSION: The purified recombinant Sj22.6 protein and Sj22.6/Sj26 GST fusion protein had the same immunological activity as the native Sj22.6 kDa protein.

Animals↗
PubMed1999

[Studies on immunoprotection in mice after immunization with Schistosoma japonicum 22.6 kDa recombinant protein].

AIM: To evaluate the immunoprotective effect of Schistosoma japonicum recombinant 22.6 kDa (rSj22.6) and Sj22.6/Sj26 GST fusion protein. METHODS: The Sj22.6/Sj26 GST fusion protein was prepared by affinity chromatography using glutathione Sepharose 4B. The purified rSj22.6 could be cleaved easily from the fusion protein with Thrombin. 17 and 12 mice immunized with rSj22.6 and Sj22.6/Sj26 GST separately were each challenged with 40 +/- 1 S. japonicum cercariae. RESULTS: In BALB/c mice, the rSj22.6 and Sj22.6/Sj26 GST could induce 32.1 (P < 0.005) and 34.9% (P < 0.02) worm reduction, respectively, as well as 28.4% (P < 0.02) and 45.1% (P < 0.005) total egg reduction, respectively. CONCLUSION: Bpth rSj22.6 and Sj22.6/Sj26 GST fusion protein are partially effective against S. japonicum.

Animals↗
PubMed1999

[Fluorescence studies on amoxicillin].

The effects of pH, various organic solvents such as acetone, methanol, ethanol, surface-active agent on amoxicillin have been studied in detail. Put in pH=8 buffer solution, amoxicillin has strong fluorescence emission, excitaion wavelength of 277 nm, and emission wavelength of 303 nm. Calibration curve of amoxicillin was linear between 2 x 10(-5) and 2 x 10(-4) mol/L, with a regression coefficient of 0.9996. CTAB can enhance its fluorescence intensity. The results of fluorescence spectra of amoxicillin added with metal ions (Mg2+, Ca2+, Al3+, Ga3+) at pH=12 showed that there are interactions between amoxicillin and metal ions.

Amoxicillin↗
PubMed1999

[Fluorescence study on phenothiazine and its halogenate derivatives].

The fluorescence spectra of 3-bromine-N-ethyl-phenothiazine with various acid degrees and different polarity surfactants in aqueous solutions were studied in detail. The reasons why fluorescence spectra of Br-Pwere very sensitive to environmental polar and acid changes were discussed based on Lewis acid-base theory. Meanwhile the spectrum of Br-P under ultraviolet ray illumination showed that Br-P had kinetic fluorescence. The method is not only simple but also sensitive with low limit of detection. The calibration curves were linear between 1 x 10(-7) and 1 x 10(-4) mol/L, with a regression coefficient of 0.9995 and RSD<2.8%.

English Abstract↗
PubMed1998

The Arp2/3 complex mediates actin polymerization induced by the small GTP-binding protein Cdc42.

The small GTP-binding protein Cdc42 is thought to induce filopodium formation by regulating actin polymerization at the cell cortex. Although several Cdc42-binding proteins have been identified and some of them have been implicated in filopodium formation, the precise role of Cdc42 in modulating actin polymerization has not been defined. To understand the biochemical pathways that link Cdc42 to the actin cytoskeleton, we have reconstituted Cdc42-induced actin polymerization in Xenopus egg extracts. Using this cell-free system, we have developed a rapid and specific assay that has allowed us to fractionate the extract and isolate factors involved in this activity. We report here that at least two biochemically distinct components are required, based on their chromatographic behavior and affinity for Cdc42. One component is purified to homogeneity and is identified as the Arp2/3 complex, a protein complex that has been shown to nucleate actin polymerization. However, the purified complex alone is not sufficient to mediate the activity; a second component that binds Cdc42 directly and mediates the interaction between Cdc42 and the complex also is required. These results establish an important link between a signaling molecule, Cdc42, and a complex that can directly modulate actin networks in vitro. We propose that activation of the Arp2/3 complex by Cdc42 and other signaling molecules plays a central role in stimulating actin polymerization at the cell surface.

Actin-Related Protein 2↗
PubMed1998

[Development of an in vitro model of culture using mouse fetal long bone].

An in vitro model of culture using mouse fetal long bone was firstly established using self-made turning-equipment. The bone formation, mineralization and resorption were observed simultaneously in cultured bone. It provided a useful model for investigating the relationship between bone, development and the effect of nutrients, toxicants and other factors.

Animals↗