Trypanosoma gambiense and T. equiperdum: characterization of variant specific antigens

It has been shown that by a simple procedure the variant specific protective antigen can be isolated from both T. gambiense and T. equiperdum. The protection afforded mice by this antigen is relatively long term and a high percentage of mice has complete protection. It has been suggested that the antigens are highly antigenic and although antigenically unique for each relapse strain, they have one or more common physical characteristic. It is therefore hypothesized that a multivalent vaccine might be prepared by similar procedures for protection against trypanosomiasis.     

A structural and a functional aspect of stable information processing by the brain

Brain is an expert in producing the same output from a particular set of inputs, even from a very noisy environment. In this article a model of neural circuit in the brain has been proposed which is composed of cyclic sub-circuits. A big loop has been defined to be consisting of a feed forward path from the sensory neurons to the highest processing area of the brain and feed back paths from that region back up to close to the same sensory neurons. It has been mathematically shown how some smaller cycles can amplify signal. A big loop processes information by contrast and amplify principle. How a pair of presynaptic and postsynaptic neurons can be identified by an exact synchronization detection method has also been mentioned. It has been assumed that the spike train coming out of a firing neuron encodes all the information produced by it as output. It is possible to extract this information over a period of time by Fourier transforms. The Fourier coefficients arranged in a vector form will uniquely represent the neural spike train over a period of time. The information emanating out of all the neurons in a given neural circuit over a period of time can be represented by a collection of points in a multidimensional vector space. This cluster of points represents the functional or behavioral form of the neural circuit. It has been proposed that a particular cluster of vectors as the representation of a new behavior is chosen by the brain interactively with respect to the memory stored in that circuit and the amount of emotion involved. It has been proposed that in this situation a Coulomb force like expression governs the dynamics of functioning of the circuit and stability of the system is reached at the minimum of all the minima of a potential function derived from the force like expression. The calculations have been done with respect to a pseudometric defined in a multidimensional vector space.     

Visfatin 与2 型糖尿病研究新进展

Visfatin是Fukuhara等发现的一种蛋白质细胞因子,由内脏脂肪细胞分泌,受多种因素调节,有烟酰胺磷酸核糖转移酶活性,类胰岛素作用,促炎作用等多种生物学作用。2型糖尿病是一种内分泌代谢性疾病,由多基因遗传因素、环境因素综合作用引起,visfatin与其有密切的关系。Visfatin对于寻找糖尿病新的药物靶点,开发新的疾病生物标志物有非常重要临床意义。     

Identification of the mitochondrial carnitine carrier in Saccharomyces cerevisiae

The mitochondrial carrier protein for carnitine has been identified in Saccharomyces cerevisiae. It is encoded by the gene CRC1 and is a member of the family of mitochondrial transport proteins. The protein has been over-expressed with a C-terminal His-tag in S. cerevisiae and isolated from mitochondria by nickel affinity chromatography. The purified protein has been reconstituted into proteoliposomes and its transport characteristics established. It transports carnitine, acetylcarnitine, propionylcarnitine and to a much lower extent medium- and long-chain acylcarnitines.     

类产碱假单胞菌酪氨酸酶基因重组子所产黑色素性质的研究

将构建的含有嗜麦芽假单胞菌酪氨酸酶基因的重组质粒导入从自然病死蝇蛆体内分离的具有显著杀蛆作用的类产碱假单胞菌体内 ,使后者获得了稳定产生黑色素的能力 ,具有很强的抗辐射作用。所产黑色素是无定形物质 ,在大多数有机和无机溶剂中溶解度低或不溶解 ,在碱性溶液中有较好的溶解性 ,在中性及弱酸性溶液中溶解度低 ,在pH <4的溶液中沉淀 ;可用过氧化氢或次氯酸钠氧化 ,也能被银离子或硫化氢还原 ;含有自由基 ,并能清除由紫外线诱导产生的自由基 ;能吸收所有波长的光线 ,在紫外波长下吸收值最大 ,能有效地保护紫外辐射对蛋白质及DNA等生物大分子物质的损害。     

The statistical reliability of synapomorphic analyses

A statistical test has been developed to ascertain whether a given number of presumptive synapomorphies between one pair of taxa is significantly greater than the number between another pair of taxa. This is shown to be a form of testing the significance of a difference between two proportions. It is necessary first to adjust for common patterns of synapomorphy that raise or lower both numbers. The method has been checked by simulation, and is illustrated by data on the relationships of tetrapods. It proves that Hennigian cladistics has statistical constraints.     

Partial purification of a cyclic amp phosphodiesterase from soybean callus Isolation of a non-dialysable inhibitor

Cyclic AMP phosphodiesterase has been partially purified from soybean liquid suspension culture. It has a K_m of 6.7·10^?5 M and an optimum pH of 4.2. Its activity is not affected by inorganic cations. Methyl xanthines and papaverine are not inhibitory. It is inhibited by inorganic phosphate and dibutyryl cyclic AMP. At least 35% of the total phosphodiesterase activity of the cell is associated with the plasmalemmaThe enzyme can be resolved into two fractions by DEAE-cellulose chromatography. These have apparently identical properties and each is associated with acid phosphatase activity. It is suggested that these two fractions may represent different aggregation states of a multienzyme complex.A non-dialysable inhibitor of the enzyme has been isolated by gel filtration on Sephadex G-75. It is heat stable and its association with phosphodiesterase is reversible.     

The purification and characterization of a beta-glucosidase from Alcaligenes faecalis

The beta-glucosidase from Alcaligenes faecalis has been purified to homogeneity (880-fold purification, 11% yield) using a combination of classical techniques and medium pressure ion-exchange chromatography. It is a dimeric enzyme of monomer molecular weight 50,000 and has no specific requirement for divalent metal ions. It has a high specificity for beta-glucosides and hydrolyses a wide variety of different chemical types wit retention of configuration at the anomeric centre. It has no exo-beta-1,4-glucanase activity. It is reversibly inhibited by a variety of sugars which have been shown previously to be very active against glucosidases, suggesting a normal mechanism of action. Measured Km values for cellobiose and p-nitrophenyl beta-D-glucopyranoside are quite low (0.70 and 0.08 mM, respectively), making this a good choice for cocloning into a cellulase system optimized for glucose production.     

Partial purification and characterization of an enzyme from pea nuclei with protein tyrosine phosphatase activity

A pea (Pisum sativum L.) nuclear enzyme with protein tyrosine phosphatase activity has been partially purified and characterized. The enzyme has a molecular mass of 90 kD as judged by molecular sieve column chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Like animal protein tyrosine phosphatases it can be inhibited by low concentrations of molybdate and vanadate. It is also inhibited by heparin and spermine but not by either the acid phosphatase inhibitors citrate and tartrate or the protein serine/threonine phosphatase inhibitor okadaic acid. The enzyme does not require Ca2+, Mg2+, or Mn2+ for its activity but is stimulated by ethylenediaminetetraacetate and by ethyleneglycolbis(beta-aminoethyl ether)-N,N'-tetraacetic acid. It dephosphorylates phosphotyrosine residues on the four different 32P-tyrosine-labeled peptides tested but not the phosphoserine/threonine residues on casein and histone. Like some animal protein tyrosine phosphatases, it has a variable pH optimum depending on the substrate used: the optimum is 5.5 when the substrate is [32P]tyrosine-labeled lysozyme, but it is 7.0 when the substrate is [32P]tyrosine-labeled poly(glutamic acid, tyrosine). It has a Km of 4 microM when the lysozyme protein is used as a substrate.     

Obtaining ribosome crystals in homogenates

Chick embryos are homogenized in order to analyse ribosome crystallization. Ribosome crystallization has been induced by hypothermic treatment in chick embryos homogenate. Tetramers and crystals were produced by gradually inducing the temperature over a span of 10 h to 4 degrees C. It has been observed that the concentration of KCl in the buffer is a critical point. It is suggested that the nuclear fraction is engaged in ribosome crystallization.     

Methyl 5'-(6-aminopurin-9-yl)-5'-deoxy-beta-D-ribofuranoside 2',3'-cyclic monophosphate: a novel, biologically active, structural analogue of cyclic AMP

A novel structural analogue of cyclic AMP has been synthesized. This compound has been found to activate protein kinase from skeletal muscle (Ka 5.0 microM). It is virtually resistant to degradation by beef heart cAMP phosphodiesterase. It is an inhibitor of this enzyme with an [I]50 of 47.0 microM. The proliferation of cancer cells (HT-29) is inhibited by this compound. It represents the first example of a 2',3'-cyclic nucleotide with marked biological activity.     

Stimulatory factor for tRNA aminoacylation: possible product of modifier genes in Drosophila melanogaster

A factor which stimulates the aminoacylation of heterologous and homologous tRNAs for lysine and leucine, as well as a mixture of amino acids, has been isolated from cytoplasmic extracts in Drosophila. The stimulatory factor is separated from inorganic pyrophosphatase activity by DEAE-cellulose chromatography and from aminoacyl-tRNA synthetase activity by trichloroacetic acid precipitation. It contains no nucleotidyl transferase activity. It is trypsin-sensitive and heat-stable, indicating that it may be a small protein. Attempts to measure the molecular weight, however, indicate heterogeneity in size, ranging from 20,000 to 65,000. The A53g mutant has four times as much factor Ore-R adults at 0-2 days; by 6-8 days the level has declined to less than one and a half times that of Ore-R. The heightened aminoacylation activity in the mutant extract is accompanied by increased soluble protein levels. It is known that the stimulation of tRNA aminoacylation in A53g is controlled by modifier genes which enhance the expression of the A53g mutant. The possibility that the stimulation factor is a product of the modifier genes is examined.     

Proteasomal degradation: from addressing of substrates to therapeutical perspectives

The proteasome is the main intracellular proteolytic machinery. It is involved in all major cellular functions and decisions. It has long been thought that prior ubiquitinylation of almost all of its substrates was necessary for degradation. It has also long been considered that ubiquitinylation and degradation were two uncoupled mechanisms and that the recruitment of ubiquitinylated species was only performed by specialized subunits of the proteasome. The recent literature questions this simplified view. It also suggests that, on the one hand, the fraction of proteins hydrolyzed by the proteasome independently of their ubiquitinylation has largely been underestimated and, on the other hand, that the recognition of ubiquitinylated proteins involves complex addressing systems. Furthermore, it indicates a higher order structuration of the ubiquitin/proteasome pathway, a fraction of the proteasome and of ubiquitinylation enzymes being engaged in supramolecular complexes. Finally, proteasomal degradation is altered in a number of pathological situations. It, thus, constitutes a therapeutic target and the first applications are emerging.     

Human liver GTP cyclohydrolase I: purification and some properties

Human liver guanosine triphosphate (GTP) cyclohydrolase I has been purified more than 1,700-fold to what appears to be homogeneity. The active enzyme complex has an estimated molecular weight of 453,000 +/- 11,500 by gel filtration chromatography. It consists of a polypeptide of 149,000 +/- 4,000 mol wt by SDS-polyacrylamide gel electrophoresis. The activity of the enzyme is heat stable and is inhibited by di- and trivalent cations. The enzyme has an optimum pH of 7.7 in sodium phosphate buffer. It uses GTP as a sole substrate, with a Km of 116 microM.     

Effect of retabolil, biosed and vitreous body on reparative processes in the heart of rats with experimental myocardial infarction

Influence of retabolilum, biossedum and corpus vitreum on the inflammation and reparation in the rat heart with experimental infarction has been investigated. It is shown that retabolilum has the most pronounced reparation effect. At the same time biossedum has a slight effect on the reparative processes and corpus vitreum does not influence it al all. It is also found that the most pronounced action of retabolilum has been observed by the 12th day of infarction.     

Purification of a protein from Bacillus thuringiensis toxic to larvae of lepidoptera

The protein toxin of the parasporal body or crystal of Bacillus thuringiensis (Mattés isolate) has been purified severalfold by a combination of Sephadex G-200 gel filtration and ammonium sulphate precipitation. It has been shown that the use of highly alkaline conditions for dissolution of the crystals does not lead to serious artifacts. The crystal toxin has been shown to be quantitatively related to the crystal antigen. It is possible that there is a second distinct toxin present in the crystal and this too can be detected by its antigenic reaction. Purified toxic protein has been hydrolysed in vitro by regurgitated Pieris brassicae gut enzymes, chymotrypsin, trypsin and subtilisin. In each case the digest contained a product that was still antigenic, had mol.wt. about 40000 and was toxic to P. brassicae larvae. Smaller toxic molecules (mol.wt. approx. 10000) that did not react as antigens were also produced by proteolysis. It is possible that these smaller molecules were hydrolytic products of the larger digestion product.     

Partial purification and characterization of a gelatin-specific protease from the culture media of human pulmonary alveolar macrophages

A gelatin-specific protease from the culture media of human pulmonary alveolar macrophages has been partial purified by gel filtration and characterized. The macrophages were obtained by bronchopulmonary lavage from the lungs of disease-free smoking volunteers. The gelatin-specific protease initially requires trypsin activation. After chromatographing the culture media on a Sephadex G-200 column, trypsin is no longer required for activation. The gelatin-specific protease reported here shares many properties of previously reported gelatinases. It is inhibited by EDTA, cysteine, dithiothreitol and serum. It is unaffected by other protease inhibitors: phenylmethylsulfonyl fluoride, tosyllysine chloromethyl ketone and p-chloromercuribenzoate. Of all substrates tested activity was observed only with gelatin. It was inactive toward collagen, elastin and methemoglobin. This enzyme may have a role in the digestion of collagen which has been cleaved by a mammalian collagenase.     

Rapid cytologic diagnosis of surgical specimens.

The application of a rapid cytologic procedure for examination of tissue submitted for immediate frozen section diagnosis is reported. Its use in various anatomical locations is described briefly. It is apparent that this technic has wide applicability in the cytologic diagnosis of lesions from all organs. It has been used by the author for the past twenty years and has been found applicable to all types of lesions from all organs.     

Surface configuration of mesothelial cells in effusions. A comparative light microscopic and scanning electron microscopic study.

Surface configuration of mesothelial cells identified by light microscopy (LM) has been studied by scanning electron microscopy (SEM). It has been shown that mesothelial cells may have a variable SEM appearance. The surfaces of a small proportion of mesothelial cells are covered by regular microvilli (MV) and show openings of the pinocytotic vesicles. The surfaces of the majority of these cells are covered by vesicles or blebs. An intermediate population of mesothelial cells, i.e., cells displaying side-by-side blebs and MV, has also been observed. The latter cells no longer display pinocytotic vesicles. Occasional mesothelial cells have smooth surfaces. It has been shown by LM and transmission electron microscopy that cells with blebs are viable and capable of mitotic activity. It is concluded that mesothelial cells, detached from their epithelial setting, lose microvilli and pinocytotic vesicles and acquire surface blebs. The possible relationship between mesothelial cells and macrophages based on surface features has been discussed.     

Ca2+ participation in vasodilator reactions

Stimulation of alpha-adrenoceptors was simulated by intraarterial injection of 0.6 mmol CaCl2 in acute experiments on resting muscles of the dog hind leg. It has been demonstrated that alpha-adrenergic stimulation of metabolism in skeletal muscles has a vasodilative effect in the muscle-supplying vessels. It has been also shown that imitation of alpha-adrenergic stimulation effect by intraarterial injection of CaCl2 causes Ca- and alpha-adrenergic-dependent vasodilative reactions. It is suggested that disturbance of vasodilative effects caused by alpha-adrenergic stimulation in the effector tissues, counteracting the direct constrictive alpha-adrenoceptor effect in the smooth muscle cells of the vessel wall, can lead to systemic impairment of the vascular tone.