Immobilization and condensation of DNA with 3-aminopropyltriethoxysilane studied by atomic force microscopy

We used different methods to modify a mica surface with 3-aminopropyltriethoxysilane (APTES), and then used it as substrate to immobilize DNA for atomic force microscopy (AFM) observation. The evaporation method and solution modifying method were investigated and evaluated. The solution modifying method was found to be relatively simple and effective. Using an APTES solution-modified mica surface, DNA immobilization appeared more reproducible and it could be imaged in liquid. The mixed solution of APTES and DNA was dropped directly onto the mica surface for AFM imaging. We found that DNA can condense in APTES water solutions. Toroids, rods and intermediate structures of condensation were captured by AFM.

Enhanced intracellular glutathione synthesis and excretion capability of Candida utilis by using a low pH-stress strategy

AIMS

To study the effect of low pH stress on glutathione (GSH) synthesis and excretion capability of GSH fermentation production in Candida utilis.

METHODS AND RESULTS

When C. utilis WSH 02-08 was cultivated in a glucose-ammonium sulfate medium without pH control, GSH leakage occurred when the pH of the medium decreased to 1.5. However, analysis of the cell viability indicated that the cells were not lysed. To further study the effect of low pH stress on GSH production, pH-controlled batch cultures were conducted, where the pH was switched from 5.5 to 1.2 at 24 h and maintained at 1.2 for 6 h. Nearly all intracellular GSH was leaked into the medium and the cell viability decreased dramatically, conceiving a long-term exposure of strain WSH 02-08 at low pH environment led to a complete cell lysis. A critical point (treated at pH 1.2 for 3 h) was experimentally determined, where most cells were alive but suffering a low pH stress. Low pH-stressed C. utilis cells displayed an increased intracellular GSH synthesis and export capability, which protected the cells against short-term low pH treatment.

CONCLUSIONS

Using this knowledge, a low pH-stress strategy was developed and applied in fed-batch production of GSH and 197.3 mg l-1 of GSH was secreted into the medium. The GSH-specific production yield could be increased from 2.11 to 2.67% (w/w), and the total GSH concentration could reach 737.1 mg l-1 and increased by 24.9%.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of GSH secretion of C. utilis at low pH. This study demonstrated the importance of the physiology-based fermentation strategy in the production of useful metabolites.

Characterization of extracellular accumulation of Zn2+ during ischemia and reperfusion of hippocampus slices in rat

The mammalian CNS contains an abundance of chelatable zinc that is sequestered in the vesicles of glutamatergic presynaptic terminals and co-released with glutamate. Considerable Zn(2+) is also released during cerebral ischemia and reperfusion (I/R) although the mechanism of this release has not been elucidated. We report here the real time observation of increase of the concentration of extracellular Zn(2+) ([Zn(2+)](o)), accompanied by a rapid increase of intracellular free Zn(2+)concentration, in the areas of dentate gyrus (DG), CA1 and CA3 in acute rat hippocampus slices during ischemia simulated by deprivation of oxygen and glucose (OGD) followed by reperfusion with normal artificial cerebrospinal fluid. A brief period of OGD caused a sustained increase of [Zn(2+)](o). Subsequent reperfusion with oxygenated medium containing glucose resulted in a further increase of [Zn(2+)](o). Longer periods of OGD caused greater increases of [Zn(2+)](o,) and subsequent reperfusion caused still further increases of [Zn(2+)](o,) regardless of OGD duration. The Zn(2+) chelator CaEDTA (10 mM) significantly reduced the increase of [Zn(2+)] induced by OGD and reperfusion. Significant regional differences of [Zn(2+)](o) over the areas of the DG, CA1 and CA3 were not observed during I/R. Neither sodium channel blockade by tetrodotoxin (2 microM), perfusion with nominally calcium-free medium nor anatomical disassociation of the DG, CA1 and CA3 regions from one another by lesioning affected the increase of [Zn(2+)](o). The non-specific nitric oxide synthase (NOS) inhibitor, Nomega-nitro-l-arginine methyl ester (1 mM), however, blocked the increase of [Zn(2+)](o) during ischemia and reperfusion. The data indicate the important role of NO in causing the release of Zn(2+) during I/R and suggest that NOS inhibitors may be used to reduce Zn(2+)-induced neuronal injury.

[Effect of neurotropin on brain edema induced by permanent focal cerebral ischemia in rats and collateral ventricular injection of carrageenan in mice]

Neurotropin, an inhibitor of the kallikrein-kinin system, has been used as an analgesic and anti-allergic drug in the clinic. The aims of this study are to evaluate the effect of neurotropin on brain edema induced by permanent focal cerebral ischemia in rats and collateral ventricular injection of carrageenan in mice and its mechanism. Drugs were given i.v. 15 minutes after middle cerebral artery occlusion in rats and immediately after carrageenan injection in mice. Brain water content was determined by wet/dry weight ratio. Results showed that neurotropin could reduce the brain edema induced by permanent focal cerebral ischemia in rats and collateral ventricular injection of carrageenan in mice at doses of 3.0, 6.0, 30.0 and 30.0 NU.kg-1 body weight. It also suggests that neurotropin reduced ischemic brain edema via inhibiting the kallikrein-kinin system.

Frequent expression of new cancer/testis gene D40/AF15q14 in lung cancers of smokers

We found a significant correlation between lung cancer in smokers and the expression of a human gene, D40, predominantly expressed in testis and cancers. In an attempt to clone a novel human gene, we screened a cDNA library derived from a human B cell line and obtained a cDNA clone that we refer to as D40. A search for public databases for sequence homologies showed that the D40 gene is identical to AF15q14. D40 mRNA is predominantly expressed in normal testis tissue. However, this gene is also expressed in various human tumour cell lines and primary tumours derived from various organs and tissues, such as lung cancer. We examined the relationship between D40 expression and clinico-pathological characteristics of tumours in primary lung cancer. D40 expression did not significantly correlate with either histological type or pathological tumour stage. However, D40 expression was observed more frequently in poorly differentiated tumours than in well or moderately differentiated ones. Furthermore, the incidence of D40 expression was significantly higher in tumours from patients who smoke than in those from non-smokers. D40/AF15q14 is the first gene in the cancer/testis family for which expression is related to the smoking habits of cancer patients.

Expression of the Recombinant Human Interleukin-11 in Pichia pastoris

Full length cDNA of human IL-11 was synthesized by DNA synthesizer. An expression plasmid, pGENYk, containing the recombinant DNA fragment, was linearized and transformed into Pichia pastoris. This recombinant gene was highly expressed in this yeast, and the expression product was purified by a three-step chromatography method. Analysis of the purified recombination protein with SDS-PAGE, Western blot and biological activities showed that the activity of the protein was the same as the Neumega expressed in E.coli.

Synthesis and Complexation of a Chiral Sexidentate Pendant-Arm Macropolycyclic Polyamino Acid

The reaction of the acyclic complex ion (methyl (SS,SS)-3-[(2�-aminocyclohexyl)amino]-2-[(2�-aminocyclohexyl)-aminomethyl]propionate)copper(II) with formaldehyde and nitroethane in basic solution yields the pendant-arm macrocyclic complex (SS,SS)-(methyl-15-methyl-15-nitro-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane-4-carboxylate)copper(ii) ion. Reduction with zinc in hydrochloric acid yields the hydrochloride salt of the pendant-arm macrocycle (SS,SS)-15-amino-15-methyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane-4-carboxylic acid (1), separated into and isolated as the major trans (1a) and minor cis (1b) isomers. Co-ordination of (1) to several metal ions [CoIII, CrIII, NiII, ZnII, CuII] and comparison with a previously reported analogue without the cyclohexane rings, trans-13-amino-13-methyl-1,4,8,11-tetraazacyclotetradecane-6-carboxylic acid (2a) salt, is described. The [Ni{(1a) – H+}](ClO4) crystallizes in the monoclinic space group P21, a 9.710(2), b 14.442(1), c 10.317(2) Å, β 96.02(2)°. The nickel displays a distorted octahedral geometry, with all four secondary amines coordinated (Ni–N range 2.044(7)–2.063(6) Å), in addition to pendant primary amine (Ni–N, 2.109(6) Å) and carboxylate (Ni–O, 2.100(6) Å) groups. Protonation constants for the trans (1a) and cis (1b) isomers and stability constants of these isomers with the labile metal ions ZnII, CdII, HgII, PbII, MnII, and CoII were determined by potentiometric titrations. The log K values for 1 : 1 complexes show small variations between geometric isomers.

Immune elimination of Leishmania major in mice: implications for immune memory, vaccination, and reactivation disease

Infection of susceptible BALB/c mice with a large, moderate, or low number of Leishmania major parasites respectively results in progressive disease, the formation of substantial but stable lesions, denoted as borderline disease, and the absence of a visible lesion. Infection with a low number of parasites results over the long term in either subclinical infections or an asymptomatic state. Subclinical mice produce a predominant Th1 response and are resistant to challenge, in contrast to their asymptomatic counterparts. Statistical and other evidence suggest that the asymptomatic state can arise from a subclinical state following parasite clearance, with consequent loss of resistance. Cell transfer studies demonstrate unequivocally that immune cells from subclinical mice can protect naive mice against a pathogenic challenge and can clear the parasite, leaving the mice susceptible to a rechallenge infection. This susceptibility is associated with the disappearance of both parasite-specific effector and memory T cells from secondary lymphoid organs. These findings have implications for vaccination, maintenance of memory, and prevention of reactivation disease.

[Advances of peripheral nerve regeneration using nerve guidance channel]

The applications and advances of nerve guidance channel used as peripheral nerve repair and regeneration have been reviewed. There are two main aspects: the design of nerve guidance channel itself, and the creation of regeneration microenvironment in the nerve guidance channel.

Vaccination against and treatment of tuberculosis, the leishmaniases and AIDS: perspectives from basic immunology and immunity to chronic intracellular infections

The occurrence of infectious disease represents a failure of the immune system, a failure that must be prevented by effective vaccination or remedied by treatment. Vaccination against acute diseases such as smallpox and polio are very effective, due to the rapid and increased immune response of vaccinated individuals upon natural infection. In contrast, effective vaccination against intracellular pathogens that cause chronic diseases, such as the leishmaniases, tuberculosis and AIDS, has not been achieved. Clinical observations suggest cell-mediated, Th1 responses, exclusive of antibody production and the generation of Th2 cells, are optimally protective against these intracellular pathogens. Effective vaccination must ensure the generation of such a protective response. We explore here whether understanding very broad features of the regulation of the immune response can accommodate modern findings on the immunological features of these diseases, and provide a perspective within which strategies for effective vaccination and treatment can be developed.

Myocardial contractile responsiveness to endothelin-1 in the post-infarction rat model of heart failure: effects of chronic quinapril

Cardiac endothelin-1 (ET-1) levels and ET receptor expression are increased in congestive heart failure (CHF). In order to determine whether this results in increased responsiveness of ET-A or ET-B receptors to ET-1, we evaluated the contractile effects of ET-1 in isolated papillary muscles isolated from hearts of control rats and from rats 4 weeks post myocardial infarction (MI) having received no therapy or chronic quinapril therapy. The ET-1 dose-response was biphasic in normal muscles. The use of the selective ET-A receptor antagonist BQ123 and the selective ET-B receptor antagonist BQ788 revealed that the initial decrease in tension was the result of ET-B receptor stimulation. Blockade of nitric oxide (NO) production with L-NAME abolished the initial decrease in tension. MI resulted in CHF that was partially reversed by quinapril. In MI, the positive inotropic effects of ET-1 were enhanced due to the loss of the initial ET-B receptor mediated decrease in tension, as well as an increase in the positive inotropic effects of ET-A receptors. This was associated with an increase in ET-A and ET-B receptor mRNA and a decrease in cardiac ecNOS protein. Four weeks of therapy with quinapril attenuated the positive inotropic effects of ET-1 and prevented the increase in ET-A receptor mRNA. Although quinapril did not restore the effects of ET-B receptor stimulation or prevent the increase in ET-B mRNA, it did restore cardiac ecNOS protein expression. Thus, the inotropic response to ET-1 is biphasic due to an overall positive inotropic effect of ET-A receptor stimulation and an ET-B receptor mediated decrease in contractility at low ET-1 concentrations which appears to be mediated by cardiac ecNOS (NO). In post-MI CHF, responsiveness to ET-A receptors increases and the ET-B mediated negative inotropic response is lost despite an increase in both receptor subtypes. Quinapril therapy attenuates these effects and normalises cardiac ecNOS protein.

A case for a neonatal, low-dose BCG vaccination trial

The rational design of a successful vaccination strategy against tuberculosis requires certain kinds of information and must take account of several considerations: (i) the nature of the immune response that protects the large majority of individuals infected by Mycobacterium tuberculosis, designated as healthy contacts, must be defined and distinguished from that in tuberculosis patients, whose immune system must have failed; (ii) the vaccination strategy must incorporate a way of priming the immune system to guarantee in all individuals this protective response, normally generated in healthy contacts, upon natural infection by M. tuberculosis; (iii) the strategy must incorporate a mechanism for ensuring that the effectiveness of this priming is not abrogated by exposure to environmental mycobacteria; and (iv) the strategy must take account of the fact that the vaccinated population is genetically heterogeneous, and that individuals will therefore respond variably to most standard vaccination protocols. We describe a tentative proposal for how these interrelated problems might be solved and discuss predictions of this tentative vaccination strategy. Critical testing of the neonatal, low-dose BCG vaccination strategy can only be achieved by a field trial and we outline the considerations underlying this proposal.

[Effect of pH on the permeability of timolol maleate across isolated rabbit cornea]

AIM

To study the effect of pH on the transcorneal permeability of timolol maleate (TM).

METHODS

The apparent distribution coefficients of TM were determined. The permeability of TM across isolated rabbit cornea was measured using in vitro method at various pH.

RESULTS

The partition coefficient and pKa of TM were 63.63 and 9.17 respectively. At neutral pH, the apparent permeation coefficient of TM was 1.43 x 10(-5) cm.s-1. When the pH varied from 6.65 to 9.20, the cumulative amount for timolol transcorneal penetration increased 1.3 times and the lag time decreased more than 19-folds. The calculated permeability coefficients of ionized and un-ionized timolol were 1.29 x 10(-5) cm.s-1 and 4.22 x 10(-5) cm.s-1, respectively.

CONCLUSION

Timolol penetrated corneal membrane mainly as free base by intracellular pathway, and corneal epithelium was the rate-limiting barrier.

[Arthropod community structures in transgenic Bt cotton fields]

Arthropod community structures were investigated in transgenic Bt cultivars, Bollgard(B) and Chinese cotton 30 (CC30), and common cultivars, control (C) and no control (NC) cotton field in North China in 1998. The results showed that compared with common cultivars, the species richness and the number of total individual of arthropod community in transgenic Bt cultivars field were reduced 2.4-16.3% and 71.0-78.3% respectively, in which dominant species in phytophagous subcommunity varied. The number of individual of predatory and parastic subcommunity were all increased. The similarity coefficient between CC30 and NC was 0.8243, B and NC 0.7320, B and C 0.3380, C and NC 0.3128, CC30 and C 0.2665. The order of diversity and evenness value of these were CC30 (2.3712 and 0.6428), NC (2.3654 and 0.6251), B (2.1364 and 0.5791), and C (1.0877 and 0.2949), their dominant value was 0.8726 (C), 0.3528(B), 0.1178(NC) and 0.1048 (CC30) respectively. It was concluded that different integrated pest management (IPM) strategy should be implemented in transgenic Bt cotton instead of common variety cotton field.

The effect of precursor structures on the action of glucosaminyl 3-O-sulfotransferase-1 and the biosynthesis of anticoagulant heparan sulfate

To understand how 2-O-sulfation of uronic acid residues influences the biosynthesis of anticoagulant heparan sulfate, the cDNA encoding glucosaminyl 3-O-sulfotransferase-1 (3-OST-1) was introduced into wild-type Chinese hamster ovary cells and mutant pgsF-17 cells, which are defective in 2-O-sulfation. 3-OST-1-transduced cells gained the ability to bind to antithrombin. Structural analysis of the heparan sulfate chains showed that 3-OST-1 generates sequences containing GlcUA-GlcN(SO(3))3(SO(3)) and GlcUA-GlcN(SO(3))3(SO(3))6(SO(3)) in both wild-type and mutant cells. In addition, IdoUA-GlcN(SO(3))3(SO(3)) and IdoUA-GlcN(SO(3))3(SO(3))6(SO(3)) accumulate in the mutant chain. These disaccharides were also observed by tagging [6-(3)H]GlcN-labeled pgsF-17 heparan sulfate in vitro with [(35)S]PAPs and purified 3-OST-1. Heparan sulfate derived from the transduced mutant also had approximately 2-fold higher affinity for antithrombin than heparan sulfate derived from the transduced wild-type cells, and it inactivated factor Xa more efficiently. This study demonstrates for the first time that (i) 3-O-sulfation by 3-OST-1 can occur independently of the 2-O-sulfation of uronic acids, (ii) 2-O-sulfation usually occurs before 3-O-sulfation, (iii) 2-O-sulfation blocks the action of 3-OST-1 at glucosamine residues located to the reducing side of IdoUA units, and (iv) that alternative antithrombin-binding structures can be made in the absence of 2-O-sulfation.

Immunohistochemical localization of interleukin-2 and its receptor subunits alpha, beta and gamma in the main olfactory bulb of the rat

Endogenous interleukin-2 (IL-2) was found in the adult rat brain, however, it has not been reported whether this cytokine is present in the olfactory bulb. Immunohistochemical techniques were used to examine the cellular localization of IL-2 and its receptor subunits in the main olfactory bulb of the rat. Strong IL-2 immunoreactivity was localized in glial cells, specifically in the olfactory nerve layer, glomerular layer and external plexiform layer. IL-2 mRNA was detected in the olfactory bulb by RT-PCR. All three IL-2 receptor subunits also showed distinct laminar distributions. The IL-2Ralpha and IL-2Rbeta immunoreactivity was found both in neurons and glial cells, whereas IL-2Rgamma imunoreactivity was found in glial cells, and thus resembled IL-2 immunostaining. The present results demonstrated a wide distribution of IL-2 and its receptor subunits in the main olfactory bulb of the rat, suggesting that IL-2 might play a role in the olfactory function through autocrine or paracrine pathways. The exclusive high expression of IL-2 in glial cells in distinct laminar structures, where neuron-glia interactions are closely associated with olfactory nerve regeneration, imply that IL-2 might be involved in the process of nerve regeneration in the olfactory bulb.

Stem cell plasticity in mammals and transdetermination in Drosophila: common themes?

Stem cells have been identified in a number of mammalian tissues (e.g. bone marrow, muscle, gut, skin, and neural tissues). Until recently, it was generally believed that the differentiation potential of a mammalian somatic stem cell is restricted to one tissue only, as in the case of hematopoietic stem cells differentiating into hematopoietic cells. In this sense, somatic stem cells are limited in their differentiation potential. Several lines of evidence now challenge the idea of unilateral development. New reports show mammalian somatic stem cells can, in the course of regeneration, repopulate heterologous cell systems and therefore possess a surprisingly broad spectrum of differentiation potential. Thus, mammalian stem cells are apparently capable of fate changes between stem cell systems, although the mechanisms leading to such changes are unclear. Mechanistic models for fate changes have been proposed in Drosophila, specifically for transdetermination of imaginal discs. Imaginal discs of the larva are the primordia of the adult exoskeleton and appendages, for example, legs, and antennae. Transplantation experiments of imaginal discs have shown that discs are determined for their disc identity. Transdetermination in Drosophila refers to cases when, after regenerative cell divisions, imaginal disc cells change from one state of determination to another, initiating a pathway of differentiation leading to structures other than those corresponding to the initial state or determination; for example, an antennal imaginal disc transdetermines to a leg imaginal disc. A fate change is thus possible in both mammalian somatic stem cells and Drosophila imaginal discs following transplantation and subsequent proliferation. Here we summarize and compare observations made in such cases of stem cell and imaginal disc differentiation.

Regulation of glial cell line-derived neurotrophic factor expression by electroacupuncture after transient focal cerebral ischemia

The present study was designed to investigate whether electroacupuncture (EA) is able to regulate glial cell line-derived neurotrophic factor (GDNF) expression following transient middle cerebral artery occlusion (MCAO) using reverse transcriptase polymerase chain reaction and immunohistochemistry in rats. The results indicate that after 2 h MCAO, GDNF mRNA and immunoreactivity profoundly increased in peri-infarct cerebral cortex, with peaks at 2 h after reperfusion, then declined dramatically at 12 and 24 h after reperfusion. Although EA given immediatelly after MCAO couldn't elevate the peaks of GDNF expression, it obviously raised the GDNF mRNA and immunoreactivity levels at 12 h after reperfusion, delayed the declining trends of GDNF mRNA and immunoreactivity levels. These results suggest that EA could upregulate GDNF expression after ischemic insult, elongating the duration of upregulated GDNF expression. This may be one of the mechanisms of EA anti-ischemic injury by augmenting endogenous protective mechanism.

Nitric oxide and peroxynitrite in postischemic myocardium

Alterations in the production of nitric oxide (NO.) are a critical factor in the injury that occurs in ischemic and reperfused myocardium; however, controversy remains regarding the alterations in NO. that occur and how these alterations cause tissue injury. As superoxide generation occurs during the early period of reperfusion, the cytotoxic oxidant peroxynitrite (ONOO-) could be formed; however, questions remain regarding ONOO- formation and its role in postischemic injury. Electron paramagnetic resonance spin trapping studies, using the NO. trap Fe(2+)-N-methyl-D-glucamine dithiocarbamate (Fe-MGD), and chemiluminescence studies, using the enhancer luminol, have been performed to measure the magnitude and time course of NO. and ONOO- formation in the normal and postischemic heart. Isolated rat hearts were subjected to control perfusion, or ischemia followed by reperfusion in the presence of Fe-MGD with electron paramagnetic resonance measurements performed on the effluent from these hearts. Whereas only trace signals were present prior to ischemia, prominent NO. adduct signals were seen during the first 2 min of reflow. The reperfusion associated increase in these NO. signals was abolished by nitric oxide synthase inhibition. In hearts perfused with luminol to detect ONOO- formation, a similar marked increase was seen during the first 2 min of reperfusion that was blocked by nitric oxide synthase inhibitors and by superoxide dismutase. Either NG-nitro-L-arginine methyl ester or superoxide dismutase treatment resulted in more than twofold higher recovery of contractile function than in untreated hearts. Immunohistology studies demonstrated that the ONOO(-)-mediated nitration product nitrotyrosine was formed in postischemic hearts, but not in normally perfused controls. Thus, NO. formation is increased during the early period of reperfusion and reacts with superoxide to form ONOO-, which results in protein nitration and myocardial injury.

Preparation and some physicochemical properties of cross-linked poloxamer hydrogel spheres

The principal purpose of this paper is to report the preparation of cross-linked poloxamer hydrogel spheres in an aqueous two-phase system without the use of organic solvent and additional emulsifier and physicochemical properties related to drug release. Poloxamer 188 was modified with methacryloyl chloride to obtain the polymerizable derivative (macromer). The aqueous solution of the macromer was mixed with dextran/magnesium sulfate aqueous solution to form a water-in-water emulsion system. After polymerizing the macromer in the dispersion phase, nonporous particles with a mean diameter of micron level were prepared. Both the mean diameter and swelling ratio of spheres can be tailored by varying the starting composition of the preparations. The drug release experiments indicate that the release of vitamin B12 entrapped in the spheres follows first-order kinetics.

[Analysis on 16S rDNA sequence of rhizobia isolated from Kummerowla sp]

Based on the previous studies on numerical taxonomy, SDS-PAGE of whole-cell protein and DNA hybridization, the rhizobial strains isolated from Kummerowia sp. in semi-arid area of North-west constituted a new subgroup, the 16S rDNA sequence of representative strain SH714 were tested. The unrooted phylogenetic tree was produced. In this tree, the strain SH714 with Sinorhizobium xinjiangensis, S. fredii, S. meliloti, S. medicae, S. saheli and S. teranga constituted a branch of Sinorhizobium. Within this branch, the similarity valuse of 16S rDNA sequence between strain SH714 and S. xinjiangesis, S. fredii, S. meliloti, S. medicae, S. saheli and S. teranga were 97.4%, 97.5%, 96.8%, 96.7%, 97.2% and 95.6% respectively, the values were more than 95%, this indicated that these known species should belong to the same genus. The values of DNA homology between type strains of these species were less than 70%. Thus, the strain SH714 represented a new rhizobial species, and there were some diversity between SH714 and known rhizobial species in phenotypic feature and composition of protein.

Effect of diazepam on the contents of amino acids and free radical during ischemia/reperfusion injury

The protective effect and mechanism of diazepam on ischemia neurons during cerebral ischemia and reperfusion were studied. Sixty-three Wistar rats were divided randomly into nine groups: control group (n = 7), ischemia (is) groups including subgroups of is3 h, is3-h/rep1-h, is3-h/rep2-h, is3-h/rep3-h(n = 7 in each group), diazepam treated groups (10 mg/kg, i.p.), including subgroups of is3-h, is3-h/rep1-h, is3-h/rep2-h, is3-h/rep3-h (n = 7 in each group) with Zea longa's animal model of middle cerebral artery occlusion. The comparison between the ischemia group and diazepam-treated group showed that diazepam could obviously decrease the production of glutamate, asparate, MDA and increase the synthesis and release of GABA, SOD and GSH-PX. It was concluded that diazepam exerted its protective effects on neurons through complex mechanisms of regulating the synthesis and release of excitotary/inhibitory amino acids and free radicals.

ets-2 is a target for an akt (Protein kinase B)/jun N-terminal kinase signaling pathway in macrophages of motheaten-viable mutant mice

The transcription factor ets-2 was phosphorylated at residue threonine 72 in a colony-stimulating factor 1 (CSF-1)- and mitogen-activated protein kinase-independent manner in macrophages isolated from motheaten-viable (me-v) mice. The CSF-1 and ets-2 target genes coding for Bcl-x, urokinase plasminogen activator, and scavenger receptor were also expressed at high levels independent of CSF-1 addition to me-v cells. Akt (protein kinase B) was constitutively active in me-v macrophages, and an Akt immunoprecipitate catalyzed phosphorylation of ets-2 at threonine 72. The p54 isoform of c-jun N-terminal kinase-stress-activated kinase (JNK- SAPK) coimmunoprecipitated with Akt from me-v macrophages, and treatment of me-v cells with the specific phosphatidylinositol 3-kinase inhibitor LY294002 decreased cell survival, Akt and JNK kinase activities, ets-2 phosphorylation, and Bcl-x mRNA expression. Therefore, ets-2 is a target for phosphatidylinositol 3-kinase-Akt-JNK action, and the JNK p54 isoform is an ets-2 kinase in macrophages. Constitutive ets-2 activity may contribute to the pathology of me-v mice by increasing expression of genes like the Bcl-x gene that promote macrophage survival.

sqv-3, -7, and -8, a set of genes affecting morphogenesis in Caenorhabditis elegans, encode enzymes required for glycosaminoglycan biosynthesis

sqv (squashed vulva) genes comprise a set of eight independent loci in Caenorhabditis elegans required zygotically for the invagination of vulval epithelial cells and maternally for normal oocyte formation and embryogenesis. Sequencing of sqv-3, sqv-7, and sqv-8 suggested a role for the encoded proteins in glycolipid or glycoprotein biosynthesis. Using a combination of in vitro analysis of SQV enzymatic activities, sqv(+)-mediated rescue of vertebrate cell lines, and biochemical characterization of sqv mutants, we show that sqv-3, -7, and -8 all affect the biosynthesis of glycosaminoglycans and therefore compromise the function of one specific class of glycoconjugates, proteoglycans. These findings establish the importance of proteoglycans and their associated glycosaminoglycans in epithelial morphogenesis and patterning during C. elegans development.

Location of the glucuronosyltransferase domain in the heparan sulfate copolymerase EXT1 by analysis of Chinese hamster ovary cell mutants

Heparan sulfate formation occurs by the copolymerization of glucuronic acid (GlcA) and N-acetylglucosamine (GlcNAc) residues. Recent studies have shown that these reactions are catalyzed by a copolymerase encoded by EXT1 and EXT2, members of the exostosin family of putative tumor suppressors linked to hereditary multiple exostoses. Previously, we identified a collection of Chinese hamster ovary cell mutants (pgsD) that failed to make heparan sulfate (Lidholt, K., Weinke, J. L., Kiser, C. S., Lugemwa, F. N., Bame, K. J., Cheifetz, S., Massagué, J., Lindahl, U., and Esko, J. D. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 2267-2271). Here, we show that pgsD mutants contain mutations that either alter GlcA transferase activity selectively or that affect both GlcNAc and GlcA transferase activities. Expression of EXT1 corrects the deficiencies in the mutants, whereas EXT2 and the related EXT-like cDNAs do not. Analysis of the EXT1 mutant alleles revealed clustered missense mutations in a domain that included a (D/E)X(D/E) motif thought to bind the nucleotide sugar from studies of other transferases. These findings provide insight into the location of the GlcA transferase subdomain of the enzyme and indicate that loss of the GlcA transferase domain may be sufficient to cause hereditary multiple exostoses.

Prognostic impact of INK4A deletion in Ewing sarcoma

BACKGROUND

The primary genetic alteration in > 95% of Ewing sarcomas (ES) is a specific fusion of EWS with FLI1 or ERG. Secondary genetic alterations possibly involved in progression of ES are not well understood. A recent study found loss of the negative cell cycle regulator gene INK4A in 8 of 27 ES samples (30%). To confirm these findings and evaluate their prognostic significance, the authors studied INK4A deletion in 41 ES samples from 39 patients.

METHODS

Using Southern blot analysis with an INK4A p16 cDNA probe, the intensity of the INK4A bands in ES DNA samples was normalized to that of a control probe and compared with nondeleted control DNA; > 50% signal reduction was scored as evidence of deletion. All ES tumor DNA samples previously were confirmed to have EWS rearrangements on the same Southern blots, using a cDNA probe spanning the EWS breakpoint region.

RESULTS

Tumors from 7 patients (18%) showed INK4A deletion independent of disease stage (localized or metastatic) or sample source (primary tumor or metastasis). INK4A was a strong negative factor for disease specific survival in univariate analysis (P = 0.001) and in multivariate analysis including stage (relative risk = 6; P = 0.001).

CONCLUSIONS

INK4A deletions appear to be the most frequent secondary molecular genetic alteration found to date in ES. Their possible clinical usefulness in identifying a subset of ES patients with poor prognosis merits systematic prospective analysis. [See related article on pages 783-92.]

Disruption of gastrulation and heparan sulfate biosynthesis in EXT1-deficient mice

Mutations in the EXT1 gene are responsible for human hereditary multiple exostosis type 1. The Drosophila EXT1 homologue, tout-velu, regulates Hedgehog diffusion and signaling, which play an important role in tissue patterning during both invertebrate and vertebrate development. The EXT1 protein is also required for the biosynthesis of heparan sulfate glycosaminoglycans that bind Hedgehog. In this study, we generated EXT1-deficient mice by gene targeting. EXT1 homozygous mutants fail to gastrulate and generally lack organized mesoderm and extraembryonic tissues, resulting in smaller embryos compared to normal littermates. RT-PCR analysis of markers for visceral endoderm and mesoderm development indicates the delayed and abnormal development of both of these tissues. Immunohistochemical staining revealed a visceral endoderm pattern of Indian hedgehog (Ihh) in wild-type E6.5 embryos. However, in both EXT1-deficient embryos and wild-type embryos treated with heparitinase I, Ihh failed to associate with the cells. The effect of the EXT1 deletion on heparan sulfate formation was tested by HPLC and cellular glycosyltransferase activity assays. Heparan sulfate synthesis was abolished in EXT1 -/- ES cells and decreased to less than 50% in +/- cell lines. These results indicate that EXT1 is essential for both gastrulation and heparan sulfate biosynthesis in early embryonic development.

Chromosomal assignment of a novel human gene D40

We have previously reported an identification of a novel human cellular factor, D40. Here, we report the chromosomal localization of the gene that encodes D40. Fluorescent in situ hybridization (FISH) was performed to determine the chromosomal region that D40 gene resides. The chromosomes that derived from normal adult male lymphocytes were hybridized with a mixture of cDNA probes that cover the entire coding region of D40. D40 gene mapped to the long arm of chromosome 15q14-15.

Microdialysis sampling coupled to HPLC for transdermal delivery study of ondansetron hydrochloride in rats

The transdermal delivery of ondansetron hydrochloride (ON) solution in propylene glycol (PG) with a widely used penetration enhancer, oleic acid (OA), was studied in rats by a microdialysis sampling technique. Dialysate samples collected from the probe were directly injected into the HPLC system without any pre-treatment and no interference occurred in the blank sample. A good linearity between the standard concentrations and peak areas within the calibration range was achieved. In vivo recovery (32.52 +/- 1.8%) of the probe was assessed with the retrodialysis method, which was used to calculate the ON concentration in the dermis. Oleic acid at the concentrations of 2% and 5% (w/v) increased the steady-state delivery rate from 0.001 to 0.030 and 0.058 microg/h, respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.

Dynamic expression of glial cell line-derived neurotrophic factor after cerebral ischemia

The aim of this study was to understand the possible involvement of glial cell line-derived neurotrophic factor (GDNF) in rat brain ischemic injury by examining the expression and the cellular location of GDNF with molecular biological and morphological techniques. Expression of GDNF mRNA and protein was first increased as early as 2h after ischemia-reperfusion in peri-infarct cerebral cortex and striatum; it then declined, and showed a second increase at 72 h. Double staining confirmed that the earlier peak of GDNF expression was of neuronal origin and the later peak of glial origin. Considering the neurotrophic characteristics of GDNF, our findings suggest that elevated endogenous GDNF expression may have important roles in protection of ischemic injured neuronal cells.

[GC-MS analysis of volatile componments in root of Ficus hitra]

The volatile components in root of Ficus hitra Vahl were analyzed by GC-MS, the results suggested that the main volatile components in root of Ficus hitra Vahl were Hexadecanoic acid, Oleic acid, Linolic acid and Ethyl Acetate; its ether extract contains Isopsoralen and Bergapten. Coumarins should be one of the effective sections in root of Ficus hitra Vahl.

JC virus binds to primary human glial cells, tonsillar stromal cells, and B-lymphocytes, but not to T lymphocytes

The human polyomavirus, JCV, is the etiological agent of the fatal central nervous system demyelinating disease, progressive multifocal leukoencephalopathy (PML). In PML patients, JC Virus (JCV) can be detected in glial cells in the central nervous system (CNS); in B-lymphocytes in the peripheral blood, bone marrow, spleen, and tonsil; and in tonsillar stromal cells. In vitro, JCV infects glial cells, tonsillar stromal cells, and to a limited extent B-lymphocytes. The presence or absence of as yet unidentified cell type specific transcription factors contributes to the restricted tropism of JCV for these cell types. However, several studies indicate that cell surface receptors may also contribute to the limited host range of JCV. To examine this latter possibility we measured the binding of purified JCV virions to primary cultures of glial cells, tonsillar stromal cells, peripheral blood lymphocytes, and to several established cell lines. Our results demonstrate that JCV binds to primary glial cells, stromal cells, and B cells, but does not bind to primary T cells. In contrast, JCV bound to all cell lines tested, including the Namalwa B cell line and the Jurkat T cell line. These data are novel and demonstrate that JCV selectively interacts with cells in vivo that are known to be susceptible to infection. This selectivity appears to be lost when one examines virus binding to a variety of human, monkey, or mouse tumor cell lines. We next examined the susceptibility of primary peripheral blood lymphocytes and the Namalwa B cell line to infection with JCV. Our results demonstrate that the majority of infectious JCV virions remain cell surface associated and do not efficiently establish infection of B cells. This may explain the in vivo observation that JCV DNA is frequently detected in association with lymphocytes by PCR but that JCV mRNA is rarely detected in association with lymphocytes by reverse transcriptase PCR. These results also confirm previous data regarding the association of JCV with human B cells in vivo and support the hypothesis that B cells may be involved in trafficking of JCV to the CNS.

Myocardial postischemic injury is reduced by polyADPripose polymerase-1 gene disruption

BACKGROUND

PolyADPribose polymerase (PARP) is activated by DNA strand breaks to catalyze the addition of ADPribose groups to nuclear proteins, especially PARP-1. Excessive polyADPribosylation leads to cell death through depletion of NAD+ and ATP.

MATERIALS AND METHODS

In vivo PARP activation in heart tissue slices was assayed through conversion of [33P]NAD+ into polyADPribose (PAR) following ischemia-reperfusion (I/R) and also monitored by immunohistochemical staining for PAR. Cardiac contractility, nitric oxide (NO), reactive oxygen species (ROS), NAD+ and ATP levels were examined in wild type (WT) and in PARP-1 gene-deleted (PARP-1(-/-)) isolated, perfused mouse hearts. Myocardial infarct size was assessed following coronary artery occlusion in rats treated with PARP inhibitors.

RESULTS

Ischemia-reperfusion (I/R) augmented formation of nitric oxide, oxygen free radicals and PARP activity. I/R induced decreases in cardiac contractility and NAD+ levels were attenuated in PARP-1(-/-) mouse hearts. PARP inhibitors reduced myocardial infarct size in rats. Residual polyADPribosylation in PARP-1(-/-) hearts may reflect alternative forms of PARP.

CONCLUSIONS

PolyADPribosylation from PARP-1 and other sources of enzymatic PAR synthesis is associated with cardiac damage following myocardial ischemia. PARP inhibitors may have therapeutic utility in myocardial disease.

[Distribution patterns of shoots, flowers and seeds in Ginkgo biloba canopy and their relationships]

The distribution patterns of shoots, flowers and seeds in the canopy of 14 years old engrafted Ginkgo biloba and their relationships were investigated with stratification method. The result shows that long shoots, short shoots, bearing-shoots and flowers uniformly distributed in the central section of canopy. From the top to the bottom, the average age and the divaricating angle of long shoots increase 51.3% of the seeds distributed in 180-320 cm layer from the ground. The number of shoots, flowers and seeds in different canopy layers was closely correlated.

Breast self-examination in women in two primary care settings: an evaluation of the impact of insurance status

Breast cancer is one of the most common cancers diagnosed among women in the United States. Screening tools available for breast cancer detection include breast self-examination (BSE), clinical breast examination, and mammography. Various studies have indicated that women may inconsistently perform BSE. This investigation evaluated the potential impact of insurance status on BSE. Women with health insurance receiving primary healthcare at a health maintenance organization (HMO) and women without health insurance receiving primary healthcare at a free clinic completed anonymous questionnaires that obtained information about the frequency of BSE performance, whether instruction was given about performing BSE, age at learning BSE, and confidence in performing BSE. One hundred fifty-five (82%) of 200 questionnaires at the HMO and 92 (92%) of 100 questionnaires at the free clinic were completed. Thirty-five percent of women (32% at the HMO, 39% at the free clinic) reported performing BSE. There were no significant differences in the rate of monthly BSE, receiving instruction about performing BSE, age at learning BSE, or confidence in performing BSE in women at the HMO and free clinic. Insurance status did not affect BSE. However, further study is needed to evaluate factors that potentially influence performance of BSE and could encourage compliance with BSE recommendations.

[Hyperconjugation, characteristic infrared absorption of methylsulfones and crystal structures of selected aromaticsulfones]

A branched absorption peak with medium intensity at (970 +/- 20) cm-1 appears only in the infrared spectra of methylsulfones. The below mentioned aromaticsulfones are chosen to reveal the specificity. Crystal and molecular parameters of CH3CONH-C6H4-SO2R(R = -CH3, -CH2CH2OH)-CH2CONH2, are determined by application of single crystal diffraction of X-ray through Nicolet R3M/E diffracometer. The existence of hyperconjugation and its natures in group -SO2CH3, confirmed by further analyses on the parameters, result in the specificity of IR absorption of the group, which is proved characteristic and can be used to identify methylsulfones. The first part describes the detection results, ascertains their crystal and molecular structures, and shows that the aromaticsulfone exists as cross linking multi-molecules when R = -CH2CONH2 or as double molecules when R = -CH2CH2OH because of H bonds. The second part covers analyses on their molecular structures. The analyses demonstrate the hyperconjugation between sigma S-C and pi S-C in group -SO2CH3. The sigma C-H hyperconjugate with pi S-O. The strength of hyperconjugated bond C-H decreases and its length tends longer. Due to the effect, the bond S-C is not a pure single bond sigma, but one which possesses a certain degree of a double bond. Its IR wave number, between those of sigma S-C and pi S-C, attributes to the medium branched peak at (970 +/- 20) cm-1. The peak branch reflects two groups of the most stable hyperconjugating conformational isomers. The hyperconjugation is weakened by the substitution of one non H group for one H atom in -SO2CH3 and if the non H group does not conjugate with pi S-O, the absorption at (970 +/- 20) cm-1 disappears as a characteristic peak. The intensity of absorption at (970 +/- 20) cm-1 conforms to the intensity of hyperconjugation between pi S-O and its adjacent sigma C-H. The third part introduces syntheses of the products, crystal preparations and their detections through X-ray diffraction.

Mutational analysis of avidity and fine specificity of anti-levan antibodies

Using the polyfructose, bacterial levan, as a model polysaccharide, we analyzed how V regions affect binding in anti-polysaccharide mAbs. Previously, panels of mAb were constructed from bacterial levan-immunized BALB/c and CBA/Ca mice. The BALB/c mAb were mostly germline VHJ606:Vkappa11, and a subset contained presumed somatic mutations in the complementarity-determining regions (CDRs) that correlated with increases in avidity for the beta(2-->1) inulin linkage of levan. The CBA/Ca mAb were more heterogeneous in V gene usage, but a subset of inulin-nonreactive mAb were VHJ606:Vlambda and had VH sequence differences in the CDRs from the VHJ606 regions of the BALB/c mAb. In this report, VHJ606 Abs containing various combinations of specifically mutated H and L chains were produced by engineered transfectants and tested for inulin avidity and levan binding. Two presumed somatic mutations seen in CDRs of the BALB/c hybridomas were shown to directly cause marked increases in avidity for inulin (VH N53H, 9-fold; VL N53I, 20-fold; together, 46-fold) but not for beta(2-->6) levan. Exchange of either positions 50 or 53 in VH or the H3 loop between the BALB/c and CBA/Ca mAb resulted in either fine specificity shift or total loss of bacterial levan binding. Three-dimensional models of the V regions suggested that residues that affect binding to inulin alone are near the edge of the CDR surface, while residues involved with binding both forms of levan and affecting fine specificity are in the VH:VL junctional area.

Molecular analysis of the GCF gene identifies revisions to the cDNA and amino acid sequences(1)

GC factor (GCF) was reported as a transcriptional regulator that binds to a specific GC-rich sequence in the epidermal growth factor receptor (EGFR) gene promoter and represses its expression. In this paper, we present the data on three revisions of the cDNA sequence that lead to significant changes of the amino acid sequences of the published GCF. Firstly, 5'-rapid amplification of cDNA end (5'-RACE) analysis revealed that the 308 nucleotides of 5'-end of the previously published GCF cDNA does not exist at the 5'-end of the RACE product. Simultaneously, the correct 5'-end cDNA sequence of 31 nucleotides was identified. Secondly, the 'T' at the position 787 of the published GCF cDNA was not observed. Finally, a new sequence of 114 nucleotides was identified between the positions 851 and 852 of the published cDNA sequence. The revisions result in a GCF cDNA of 2661 nucleotides that encodes a protein of 781 amino acids, replacing the highly basic region of the amino-terminus of the published GCF with a new sequence of 147 amino acids. In this era of massive gene cloning and sequencing, this study is a warning to the biological research of recent years.

[A study on taxonomy of rhizobia isolated from Kummerwia sp. and Indigofera sp]

The rhizobial strains isolated from Kummerowia and Indigofera and the known reference strains were classified by performing numerical taxonomy. New isolated strains were divided into two new clusters at 83% similarity level. Based on the numerical taxonomy, additional isolates in each cluster were studied by using SDS-PAGE of whole-cell protein. Twenty-four strains isolated from Kummerowia fell into cluster 1. Twenty strains isolated from Indigofera fell into cluster 2. The results of G + C mol% and DNA homology analysis showed that the DNA homologies between the central strain SH713 and SHL042 and the 13 type strains were less than 61%. Thus, the rhizobial strains from Kummerowia and Indigofera were two new individual species of Rhizobium.

NBPA: a cerebral ischaemic protective agent

1. NBPA is a derivative of 3-n-butylpathalide isolated from Apium granolens Linn. 2. At concentrations ranging from 6 x 10(-6) to 10(-6) mol/L, NBPA inhibited the L-type calcium current in guinea-pig myocardial cells and cultured human neuroblastoma cells. 3. At 10(-6) mol/L, NBPA markedly inhibited calcium-dependent and -independent release of glutamate from synaptosomes. 4. The [31P] nuclear magnetic resonance spectrum has shown that pretreatment with NBPA at 15 mg/kg, i.p., improved energy metabolism. 5. In situ hybridization has shown that 10 and 20 mg/kg, i.p., NBPA prior to cerebral artery occlusion can accelerate the expression of heat shock protein 70 mRNA and inhibit c-fos mRNA expression. 6. It has been shown that NBPA decreases the nitric oxide content and bc nitric oxide synthase (NOS) activity in the global cerebral ischaemia-reperfusion model in rats. In addition, it has been shown that NBPA significantly inhibits the expression of inducible NOS protein.

Role of neuronal and endothelial nitric oxide synthase in nitric oxide generation in the brain following cerebral ischemia

Nitric oxide (NO) plays an important role in the pathogenesis of neuronal injury during cerebral ischemia. The endothelial and neuronal isoforms of nitric oxide synthase (eNOS, nNOS) generate NO, but NO generation from these two isoforms can have opposing roles in the process of ischemic injury. While increased NO production from nNOS in neurons can cause neuronal injury, endothelial NO production from eNOS can decrease ischemic injury by inducing vasodilation. However, the relative magnitude and time course of NO generation from each isoform during cerebral ischemia has not been previously determined. Therefore, electron paramagnetic resonance spectroscopy was applied to directly detect NO in the brain of mice in the basal state and following global cerebral ischemia induced by cardiac arrest. The relative amount of NO derived from eNOS and nNOS was accessed using transgenic eNOS(-/-) or nNOS(-/-) mice and matched wild-type control mice. NO was trapped using Fe(II)-diethyldithiocarbamate. In wild-type mice, only small NO signals were seen prior to ischemia, but after 10 to 20 min of ischemia the signals increased more than 4-fold. This NO generation was inhibited more than 70% by NOS inhibition. In either nNOS(-/-) or eNOS(-/-) mice before ischemia, NO generation was decreased about 50% compared to that in wild-type mice. Following the onset of ischemia a rapid increase in NO occurred in nNOS(-/-) mice peaking after only 10 min. The production of NO in the eNOS(-/-) mice paralleled that in the wild type with a progressive increase over 20 min, suggesting progressive accumulation of NO from nNOS following the onset of ischemia. NOS activity measurements demonstrated that eNOS(-/-) and nNOS(-/-) brains had 90% and < 10%, respectively, of the activity measured in wild type. Thus, while eNOS contributes only a fraction of total brain NOS activity, during the early minutes of cerebral ischemia prominent NO generation from this isoform occurs, confirming its importance in modulating the process of ischemic injury.

Quantitative assessment of Parkinson's disease deficits

OBJECTIVE

To quantitatively analyze the tremor and rigidity due to Parkinson's disease.

METHODS

38 patients with Parkinson's disease (PD) ranging in age from 45 to 72 years and 211 normal subjects aged from 16 to 76 years were investigated. The frequency and range of tremor, the muscle tone of the upper limbs in elbow were detected by a computerized video motion detecting system and a new invented apparatus which can detects skeletal muscle tone.

RESULTS

For the PD patients, the frequency of resting tremors was detected in 4 to 6 per second. For extensor and flexor in the PD patients, the value of muscle tone was higher than that of normal subjects and the value of muscle tone in flexor was higher than that of extensor. The rigidity increased gradually with repeat passive movement. The curves of rigidity were shown on computer screen or printed out. The data of rigidity were compared with the M-A Scale. A patient who was suspected to suffer from PD above by the equipments and found the muscle tone was higher than normal. In another PD patient the rigidity was obvious at one side and the muscle tone in "normal side" was also high. These equipments were used to record changes of rigidity and tremor in one more PD patient taking with different drugs in order to see the drug effect.

CONCLUSION

Quantitative methods are useful to analyse the motion disorders due to PD.

Blastocyst formation is blocked in mouse embryos lacking the splicing factor SRp20

SRp20 is a splicing factor belonging to the highly conserved family of SR proteins [1] [2] [3] [4], which have multiple roles in the regulation of constitutive and alternative splicing in vivo. It has been suggested that SR proteins are involved in bringing together the splice sites during spliceosome assembly [5]. SR proteins show partial redundancy, as each single SR protein can restore splicing activity to a splicing-deficient cytoplasmic extract (termed S-100 extract). Nevertheless, several studies demonstrate that individual SR proteins have different effects on the selection of specific alternative splice sites, and they recognize distinct RNA sequences [6] [7] [8] [9] [10] [11] [12]. Also, inactivation of two SR proteins, B52/SRp55 in Drosophila [13] or ASF/SF2 in the chicken cell line DT40 [14], is lethal, indicating the existence of nonredundant functions. Here, using Cre-loxP-mediated recombination in mice to inactivate the SRp20 gene, we found that it is essential for mouse development. Mutant preimplantation embryos failed to form blastocysts and died at the morula stage. Immunofluorescent staining showed that SRp20 is present in oocytes and early stages of embryonic development. This is the first report of mice deficient for a member of the SR protein family. Our experiments confirm that, although similar in structure, the SR proteins are not functionally redundant.

Characterization of the highly variable bioavailability of tiludronate in normal volunteers using population pharmacokinetic methodologies

Currently, the use of classical bioequivalence criteria is being called into question for certain classes of drugs such as bisphosphonates. These compounds typically possess a wide therapeutic index but may be characterized by low and variable absorption. The purpose of this communication was to characterize the highly variable bioavailability of tiludronate using a population pharmacokinetic method (NONMEM program) and compare the results to a standard 2 way cross-over bioequivalence trial in healthy subjects. Over 3500 plasma samples from 153 healthy subjects, representing 12 different clinical trials were pooled for mixed effect modeling purposes (complete data set). These studies, conducted under single and multiple dose conditions, contained all the directly comparable data available in healthy subjects administered a 400 mg dose of tiludronate. A two compartment model with first order absorption was fit to the plasma concentration-time data and a term for relative bioavailability (BA) was included. Intersubject and residual variability were modeled using a constant coefficient of variation (CCV) model. A pilot model development data set was obtained from a 24 subject cross-over bioequivalence study. Population estimates of BA and its associated 90% confidence interval of 1.12 and 0.89-1.35 compared favorably to standard bioequivalence methodology (1.15 and 0.93-1.42, respectively). Since a good fit of predicted and observed plasma concentrations as well as estimates of BA were obtained, a two compartment model with a term for BA was then applied to the complete data set. Under these conditions, BA and its 90% confidence interval were found to be 1.17 and 0.98-1.36. Intersubject variability of 31%, compared with 38% in the pilot model development data set and residual variability of 38% were seen. No differences in absorption characteristics as measured by Ka were found. Good agreement between the population pharmacokinetic parameters were observed when the pilot data set was compared with the full data set. The proposed model was confirmed by creating 10 additional smaller data sets that were matched for the number of subjects given both formulations under single and multiple dose conditions. No change in the estimate of BA was observed under these study conditions. This study demonstrated that population pharmacokinetic methodology can be applied successfully to problematical bioequivalence issues that may occur during the development process. Increasing the number of subjects in the overall analysis did not alter the estimate of BA or its 90% confidence interval, when compared to the original cross-over bioequivalence study. Bayesian approaches can be of value in large clinical trials where typically relatively few plasma samples are obtained from individual subjects.

Chinese hamster ovary cell mutants defective in glycosaminoglycan assembly and glucuronosyltransferase I

The proteoglycans of animal cells typically contain one or more heparan sulfate or chondroitin sulfate chains. These glycosaminoglycans assemble on a tetrasaccharide primer, -GlcAbeta1, 3Galbeta1,3Galbeta1,4Xylbeta-O-, attached to specific serine residues in the core protein. Studies of Chinese hamster ovary cell mutants defective in the first or second enzymes of the pathway (xylosyltransferase and galactosyltransferase I) show that the assembly of the primer occurs by sequential transfer of single monosaccharide residues from the corresponding high energy nucleotide sugar donor to the non-reducing end of the growing chain. In order to study the other reactions involved in linkage tetrasaccharide assembly, we have devised a powerful selection method based on induced resistance to a mitotoxin composed of basic fibroblast growth factor-saporin. One class of mutants does not incorporate 35SO4 and [6-3H]GlcN into glycosaminoglycan chains. Incubation of these cells with naphthol-beta-D-xyloside (Xylbeta-O-Np) resulted in accumulation of linkage region intermediates containing 1 or 2 mol of galactose (Galbeta1, 4Xylbeta-O-Np and Galbeta1, 3Galbeta1, 4Xylbeta-O-Np) and sialic acid (Siaalpha2,3Galbeta1, 3Galbeta1, 4Xylbeta-O-Np) but not any GlcA-containing oligosaccharides. Extracts of the mutants completely lacked UDP-glucuronic acid:Galbeta1,3Gal-R glucuronosyltransferase (GlcAT-I) activity, as measured by the transfer of GlcA from UDP-GlcA to Galbeta1,3Galbeta-O-naphthalenemethanol (<0.2 versus 3.6 pmol/min/mg). The mutation most likely lies in the structural gene encoding GlcAT-I since transfection of the mutant with a cDNA for GlcAT-I completely restored enzyme activity and glycosaminoglycan synthesis. These findings suggest that a single GlcAT effects the biosynthesis of common linkage region of both heparan sulfate and chondroitin sulfate in Chinese hamster ovary cells.

[Clinical features and diagnosis of cerebral venous thrombosis]

OBJECTIVE

To investigate the clinical features and imaging diagnosis of cerebral venous thrombosis.

METHODS

65 cases of cerebral venous thrombosis (CVT) were proved by angiography (n = 34) or MR (n = 44), 30 by both procedures and 6 by pathology as well. Their age ranged from 13 to 59 years (mean age 32.5), 31 were male and 34 were female.

RESULTS

The clinical manifestations were variable, but most patients had symptoms and signs of intracranial hypertension (91%)such as headache and papilledema. Nearly half of the patients had focal neurological dysfunction (49%) such as weakness of limbs and seizures and half of the patients had intracranial hypertension (51%) only. The occluded dural sinus and the clot could be visualised directly by means of magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA).

CONCLUSION

MRI and MRA are becoming the imaging investigation of choice for the diagnosis of CVT, Anticoagulation, thrombolysis and dextran may be effective measures in the treatment of cerebral venous thrombosis.

Formation of HNK-1 determinants and the glycosaminoglycan tetrasaccharide linkage region by UDP-GlcUA:Galactose beta1, 3-glucuronosyltransferases

While expression-cloning enzymes involved in heparan sulfate biosynthesis, we isolated a cDNA that encodes a protein 65% identical to the UDP-GlcUA:glycoprotein beta1, 3-glucuronosyltransferase (GlcUAT-P) involved in forming HNK-1 carbohydrate epitopes (3OSO3GlcUAbeta1,3Gal-) on glycoproteins. The cDNA contains an open reading frame coding for a protein of 335 amino acids with a predicted type II transmembrane protein orientation. Cotransfection of the cDNA with HNK-1 3-O-sulfotransferase produced HNK-1 carbohydrate epitopes in Chinese hamster ovary (CHO) cells and COS-7 cells. In vitro, a soluble recombinant form of the enzyme transferred GlcUA in beta-linkage to Galbeta1,3/4GlcNAcbeta-O-naphthalenemethanol, which resembles the core oligosaccharide on which the HNK-1 epitope is assembled. However, the enzyme greatly preferred Galbeta1, 3Galbeta-O-naphthalenemethanol, a disaccharide component found in the linkage region tetrasaccharide in chondroitin sulfate and heparan sulfate. During the course of this study, a human cDNA clone was described that was thought to encode UDP-GlcUA:Galbeta1,3Gal-R glucuronosyltransferase (GlcUAT-I), involved in the formation of the linkage region of glycosaminoglycans (Kitagawa, H., Tone, Y., Tamura, J., Neumann, K. W., Ogawa, T., Oka, S., Kawasaki, T., and Sugahara, K. (1998) J. Biol. Chem. 273, 6615-6618). The deduced amino acid sequences of the CHO and human cDNAs are 95% identical, suggesting that they are in fact homologues of the same gene. Transfection of a CHO cell mutant defective in GlcUAT-I with the hamster cDNA restored glycosaminoglycan assembly in vivo, confirming its identity. Interestingly, transfection of the mutant with GlcUAT-P also restored glycosaminoglycan synthesis. Thus, both GlcUAT-P and GlcUAT-I have overlapping substrate specificities. However, the expression of the two genes was entirely different, with GlcUAT-I expressed in all tissues tested and GlcUAT-P expressed only in brain. These findings suggest that, in neural tissues, GlcUAT-P may participate in both HNK-1 and glycosaminoglycan production.