Effects of repeated applications of chlorpyrifos on its persistence and soil microbial functional diversity and development of its degradation capability

Effects of repeated applications of chlorpyrifos on its persistence and soil microbial functional diversity were studied under laboratory conditions. The results showed that the degradation rate of chlorpyrifos increased whereas its inhibitory effect on soil microbial communities gradually decreased with application frequency of chlorpyrifos. A bacterial strain DSP capable of utilizing chlorpyrifos as a sole source of carbon and energy was isolated 21 days after the third chlorpyrifos application, which indicated that the capability of soil microorganism for degrading chlorpyrifos was formed during the experiment. It could be concluded that repeated applications of chlorpyrifos had no lasting impact on soil health.

Fast resistive reconnection regime in the nonlinear evolution of double tearing modes

Phases of nonlinear double tearing modes are studied numerically. The first two phases lead to the formation and growth of magnetic islands and are followed by a fast reconnection phase to complete the process, driven by a process of neighboring magnetic separatrices merging and magnetic islands coupling. The fast growth can be understood as a result of the island interaction equivalent to a steadily inward flux boundary driven. Resistivity dependences for various phases are studied and shown by scaling analysis for the first time. It is found that after an early Sweet-Parker phase with a eta(1/2)-scale, a slow nonlinear phase in a Rutherford regime with a eta(1)-scale is followed by the fast reconnection phase with a eta(1/5)-scale.

Anti-Müllerian hormone and 11 beta-hydroxylase show reciprocal expression to that of aromatase in the transforming gonad of zebrafish males

During development all zebrafish males first develop a "juvenile ovary" that later degenerates and transforms into a testis. In this study, individuals undergoing gonadal transformation were identified from a vas::egfp transgenic line and used for gene expression analysis of anti-Müllerian hormone (amh), ovarian aromatase (cyp19a1a) and 11 beta-hydroxylase (cyp11b, also known as P450(11 beta)) by real-time polymerase chain reaction and in situ hybridization. In the "normal (i.e., nontransforming) juvenile ovary" cyp19a1a was expressed around the oocytes, but cyp11b and amh could not be detected. During gonadal transformation cyp19a1a was down-regulated and could not be detected anymore; in contrast amh was up-regulated and highly expressed at similar regions where cyp19a1a had been expressed earlier. Furthermore, the normalized transcript levels of cyp19a1a and amh showed a reciprocal picture, i.e., the higher was the level of amh, the lower was that of cyp19a1a. Expression of cyp11b was also up-regulated but later than amh, and its localization was not related to the position of degenerating oocytes. These data indicate that amh is a candidate gene down-regulating cyp19a1a, leading to "juvenile ovary-to-testis" transformation. Whereas, cyp11b or its product, 11-ketotestosterone, is unlikely to be the inducer of zebrafish gonad transformation, as proposed earlier for some protogynous hermaphroditic fish species.

A note on chaotic unimodal maps and applications

Based on the word-lift technique of symbolic dynamics of one-dimensional unimodal maps, we investigate the relation between chaotic kneading sequences and linear maximum-length shift-register sequences. Theoretical and numerical evidence that the set of the maximum-length shift-register sequences is a subset of the set of the universal sequence of one-dimensional chaotic unimodal maps is given. By stabilizing unstable periodic orbits on superstable periodic orbits, we also develop techniques to control the generation of long binary sequences.

Adhesiveness of dental resin-based restorative materials investigated with atomic force microscopy

This study aimed to show that the polymerization contraction of dental methacrylate-based materials, when used as adhesives on hard substrate, produces voids at the material-substrate interface. This phenomenology is closely related with the nanoleakage and the sealing ability of these materials. One prime/bond system, three restorative composite resins, and one orthodontic bonding system were cured by using mirror-like glass slides as a compliance-free reference substrate. The adhesive surface was analyzed by atomic force microscopy, and the polymerization contraction of bulk material was tested by laser beam-scanning method. Nanoperiodic structure of three-dimensional (3D) images, section analysis, and roughness characteristics (R(a) and R(z)) indicated that polymerization contraction produced voids at the interface. When the adhesive surface was exposed to oral simulating fluids (water, ethanol, and lactic acid solutions), hydrolytic degradation involved some hundreds of nanometers in depth. In visible light-cured (VLC) materials, the interface porosity decreased when an irradiation pause ( approximately 2 min) was carried out during gelation.

Two different life-history strategies determine the competitive outcome between Dirhinus giffardii (Chalcididae) and Pachycrepoideus vindemmiae (Pteromalidae), ectoparasitoids of cyclorrhaphous Diptera

Dirhinus giffardii Silvestri and Pachycrepoideus vindemmiae Rondani are solitary parasitoids attacking puparia of many cyclorrhaphous flies. They are not typical ectoparasitoids, as they feed on host pupae within puparia that develop from the exoskeleton of host larvae. Dirhinus giffardii did not kill its host until the parasitoid egg developed into a larva, while P. vindemmiae permanently paralysed its host at the time of oviposition. As a result, ovipositing into a young host puparium (< 1 day old) in which the host pupa has not yet fully formed resulted in complete death of offspring in P. vindemmiae, but D. giffardii, although suffering higher mortality than in older host puparia, still showed a level of successful development. In a choice experiment, both parasitoids preferred to attack 2- to 3-day-old puparia in which the host pupae had fully formed, rather than 1-day-old host puparia. Pachycrepoideus vindemmiae always prevailed in competition because it injected venom that not only paralysed the host, but also caused the death of D. giffardii larvae in multi-parasitized hosts. Dirhinus giffardii preferred to attack unparasitized hosts rather than hosts previously parasitized by P. vindemmiae, while P. vindemmiae did not show a preference between unparasitized hosts and hosts previously parasitized by D. giffardii.

Is the Voltage Gate of Connexins CO 2 -sensitive? Cx45 Channels and Inhibition of Calmodulin Expression

The sensitivity of Cx45 channels to CO2, transjunctional voltage ( V(j)) and inhibition of calmodulin (CaM) expression was tested in oocytes by dual voltage clamp. Cx45 channels are very sensitive to V(j) and close with V(j) preferentially by the slow gate, likely to be the same as the chemical gate. With a CO2-induced drop in junctional conductance ( G(j)), both the speed of V(j)-dependent inactivation of junctional current ( I(j)) and V(j) sensitivity increased. With 40-mV V(j)-pulses, the tau of single exponential I(j) decay reversibly decreased by;40% during CO2 application, and G(j steady state)/G(j peak) decreased multiphasically, indicating that both kinetics and V(j) sensitivity of chemical/slow V(j) gating are altered by changes in [H(+)](i) and/or [Ca(2+)](i). CaM expression was inhibited with oligonucleotides antisense to CaM mRNA. With 15 min CO2, relative junctional conductance ( G(jt)/ G(jt0)) dropped to 0% in controls, but only by;17% in CaM-antisense oocytes. Similarly, V(j) sensitivity was significantly lessened in CaM-antisense oocytes. The data indicate that both the speed and sensitivity of V(j)-dependent inactivation of the junctional current of Cx45 channels are affected by CO2 application, and that CaM plays a key role in channel gating.

Newly imported larval parasitoids pose minimal competitive risk to extant egg-larval parasitoid of tephritid fruit flies in Hawaii

Competitive displacement of fruit fly parasitoids has been a serious issue in the history of fruit fly biological control in Hawaii. This concern regarding competitive risk of new parasitoids has led to an overall tightening of regulations against the use of classical biological control to manage fruit flies. Fopius arisanus (Sonan), an egg-larval parasitoid, is the most effective natural enemy of tephritid fruit flies in Hawaii. This study evaluated the competitive risk of two recently introduced larval parasitoids, Diachasmimorpha kraussii Fullaway and Psyttalia concolor (Szépligeti), to F. arisanus attacking the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Fopius arisanus won almost all intrinsic competitions against both larval parasitoids through physiological suppression of egg development. 83.3% of D. kraussii eggs and 80.2% of P. concolor eggs were killed within three days in the presence of F. arisanus larvae within the bodies of multi-parasitized hosts. The mechanism that F. arisanusemploys to eliminate both larval parasitoids is similar to that it uses against three other early established larval fruit fly parasitoids: F. vandenboschi (Fullaway), D. longicaudata (Ashmead) and D. tryoni (Cameron). It suggests that introduction of these larval parasitoids poses minimal competitive risk to F. arisanus in Hawaii.

Allosteric behaviour of 1:5 hybrids of mutant subunits of Clostridium symbiosum glutamate dehydrogenase differing in their amino acid specificity

Hybrid hexamers were made by refolding mixtures of two mutant forms of clostridial glutamate dehydrogenase. Mutant Cys320Ser (C320S) has a similar activity to the wild-type enzyme, but is unreactive with Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoate) (DTNB). The triple mutant Lys89Leu/Ala163Gly/Ser380Ala (K89L/A163G/S380A), active with norleucine but not glutamate, is inactivated by DTNB, since the amino acid residue at position 320 is a cysteine residue. The chosen ratio favoured 1:5 hybrids of the triple mutant and C320S. The renatured mixture was treated with DTNB and separated on an NAD(+)-agarose column to which only C320S subunits bind tightly. Fractions were monitored for glutamate and norleucine activity and for releasable thionitrobenzoate to establish subunit stoichiometry. A fraction highly enriched in the 1:5 hybrid was identified. Homohexamers (C320S with 40 mM glutamate and 1 mM NAD(+) at pH 8.8, or K89L/A163G/S380A with 70 mM norleucine and 1 mM NAD(+) at pH 8.5) showed allosteric activation; succinate activated C320S approx. 50-fold (EC(50)=70 mM, h=2.4), and glutarate gave approx. 30-fold activation (EC(50)=35 mM, h=2.3). For the triple mutant, corresponding values were 80 mM and 2.2 for succinate, and 75 mM and 1.7 for glutarate, but maximal activation was only about 2-fold. In the 1:5 hybrid, with only one norleucine-active subunit per hexamer, responses to glutarate and succinate were still co-operative, and activation was more extensive than in the triple mutant homohexamer. A single norleucine-active subunit can thus respond co-operatively to a substrate analogue at the other five inactive sites. On the other hand, similar hyperbolic dependence on the norleucine concentration for the hybrid and the triple mutant homohexamer reflected the inability of C320S subunits to bind norleucine. With glutamate at pH 8.8, an h value of 3.6 was obtained for the 1:5 hybrid, in contrast with an h value of 5.2 for the C320S homohexamer. The "foreign" subunit evidently impedes inter-subunit communication to some extent.

[Synthesis and spectroscopic properties of rare earth complexes with o-phthalate and 1,10-phenanthroline]

The complexes of rare earth ions (Nd3+, Sm3+) with o-phthalate and 1,10-phenanthroline have been synthesized and characterized by elemental analysis, 1H NMR, IR, and DTA-TG. The compositions of complexes have been confirmed to be RE2L3.2H2O and RE2L3 phen.2H2O (RE: rare earth ions, L: o-phthalic, phen: 1,10-phenanthroline), their far-IR and FT-Raman spectra have been discussed and studied.

Conversion of a glutamate dehydrogenase into methionine/norleucine dehydrogenase by site-directed mutagenesis

In earlier attempts to shift the substrate specificity of glutamate dehydrogenase (GDH) in favour of monocarboxylic amino-acid substrates, the active-site residues K89 and S380 were replaced by leucine and valine, respectively, which occupy corresponding positions in leucine dehydrogenase. In the GDH framework, however, the mutation S380V caused a steric clash. To avoid this, S380 has been replaced with alanine instead. The single mutant S380A and the combined double mutant K89L/S380A were satisfactorily overexpressed in soluble form and folded correctly as hexameric enzymes. Both were purified successfully by Remazol Red dye chromatography as routinely used for wild-type GDH. The S380A mutant shows much lower activity than wild-type GDH with glutamate. Activities towards monocarboxylic substrates were only marginally altered, and the pH profile of substrate specificity was not markedly altered. In the double mutant K89L/S380A, activity towards glutamate was undetectable. Activity towards L-methionine, L-norleucine and L-norvaline, however, was measurable at pH 7.0, 8.0 and 9.0, as for wild-type GDH. Ala163 is one of the residues that lines the binding pocket for the side chain of the amino-acid substrate. To explore its importance, the three mutants A163G, K89L/A163G and K89L/S380A/A163G were constructed. All three were abundantly overexpressed and showed chromatographic behaviour identical with that of wild-type GDH. With A163G, glutamate activity was lower at pH 7.0 and 8.0, but by contrast higher at pH 9.0 than with wild-type GDH. Activities towards five aliphatic amino acids were remarkably higher than those for the wild-type enzyme at pH 8.0 and 9.0. In addition, the mutant A163G used L-aspartate and L-leucine as substrates, neither of which gave any detectable activity with wild-type GDH. Compared with wild-type GDH, the A163 mutant showed lower catalytic efficiencies and higher K(m ) values for glutamate/2-oxoglutarate at pH 7.0, but a similar k(cat)/K(m) value and lower K(m) at pH 8.0, and a nearly 22-fold lower S(0.5) (substrate concentration giving half-saturation under conditions where Michaelis-Menten kinetics does not apply) at pH 9.0. Coupling the A163G mutation with the K89L mutation markedly enhanced activity (100-1000-fold) over that of the single mutant K89L towards monocarboxylic amino acids, especially L-norleucine and L-methionine. The triple mutant K89L/S380A/A163G retained a level of activity towards monocarboxylic amino acids similar to that of the double mutant K89L/A163G, but could no longer use glutamate as substrate. In terms of natural amino-acid substrates, the triple mutant represents effective conversion of a glutamate dehydrogenase into a methionine dehydrogenase. Kinetic parameters for the reductive amination reaction are also reported. At pH 7 the triple mutant and K89L/A163G show 5 to 10-fold increased catalytic efficiency, compared with K89L, towards the novel substrates. In the oxidative deamination reaction, it is not possible to estimate k(cat) and K(m) separately, but for reductive amination the additional mutations have no significant effect on k(cat) at pH 7, and the increase in catalytic efficiency is entirely attributable to the measured decrease in K(m). At pH 8 the enhancement of catalytic efficiency with the novel substrates was much more striking (e.g. for norleucine approximately 2000-fold compared with wild-type or the K89L mutant), but it was not established whether this is also exclusively due to more favourable Michaelis constants.

Purified cholera toxin B subunit from transgenic tobacco plants possesses authentic antigenicity

Cholera toxin B subunit (CTB) mature protein was stably expressed in transgenic tobacco plants under the control of the CaMV 35S promoter and TMV Omega fragment. Fusion of the PR1b signal peptide coding sequence to the CTB mature protein gene increased the expression level by 24-fold. The tobacco-synthesized CTB (tCTB) was purified to homogeneity by a single step of immunoaffinity chromatography. The purified tCTB is predominantly in the form of pentamers with molecular weight identical to the native pentameric CTB, indicating that the PR1b-CTB fusion protein has been properly processed in tobacco cells. Furthermore, by immunodiffusion and immunoelectrophoresis, we have shown that the antigenicity of the purified tCTB is indistinguishable from that of the native CTB protein.

Contribution of an aspartate residue, D114, in the active site of clostridial glutamate dehydrogenase to the enzyme's unusual pH dependence

Glutamate dehydrogenase from Clostridium symbiosum displays unusual kinetic behaviour at high pH when compared with other members of this enzyme family. Structural and sequence comparisons with GDHs from other organisms have indicated that the Asp residue at position 114 in the clostridial enzyme may account for these differences. By replacing this residue by Asn, a mutant protein has been created with altered functional properties at high pH. This mutant protein can be efficiently overexpressed in Escherichia coli, and several criteria, including mobility in non-denaturing electrophoresis, circular dichroism (CD) spectra and initial crystallisation studies, suggest a folding and an assembly comparable to those of the wild-type protein. The D114N mutant enzyme shows a higher optimum pH for activity than the wild-type enzyme, and both CD data and activity measurements show that the distinctive time-dependent reversible conformational inactivation seen at high pH in the wild-type enzyme is abolished in the mutant.

Calmodulin colocalizes with connexins and plays a direct role in gap junction channel gating

The direct calmodulin (CaM) role in chemical gating was tested with CaM mutants, expressed in oocytes, and CaM-connexin labeling methods. CaMCC, a CaM mutant with greater Ca-sensitivity obtained by replacing the N-terminal EF hand pair with a duplication of the C-terminal pair, drastically increased the chemical gating sensitivity of Cx32 channels and decreased their Vj sensitivity. This only occurred when CaMCC was expressed before Cx32, suggesting that CaMCC, and by extension CaM, interacts with Cx32 before junction formation. Direct CaM-Cx interaction at junctional and cytoplasmic spots was demonstrated by confocal immunofluorescence microscopy in HeLa cells transfected with Cx32 and in cryosectioned mouse liver. This was confirmed in HeLa cells coexpressing Cx32-GFP (green) and CaM-RFP (red) or Cx32-CFP (cyan) and CaM-YFP (yellow) fusion proteins. Significantly, these cells did not form gap junctions. In contrast, HeLa cells expressing only one of the two fusion proteins (Cx32-GFP, Cx32-CFP, CaM-RFP or CaM-YFP) revealed both junctional and non-junctional fluorescent spots. In these cells, CaM-Cx32 colocalization was demonstrated by secondary immunofluorescent labeling of Cx32 in cells expressing CaM-YFP or CaM in cells expressing Cx32-GFP. CaM-Cx colocalization was further demonstrated at rat liver gap junctions by Freeze-fracture Replica Immunogold Labeling (FRIL).

Expression of a recombinant human RGR opsin in Lentivirus-transduced cultured cells

PURPOSE

Our goals were to produce a functional recombinant RPE retinal G protein-coupled receptor (RGR) opsin for biochemical studies and to test the efficiency of a lentiviral vector for transgene expression of human RGR.

METHODS

A human RGR cDNA was cloned into a replication-defective lentiviral vector, and recombinant hRGR-Lentivirus was prepared for transduction of the ARPE-19, a human retinal pigment epithelium (RPE) cell line, and COS-7 cells. Recombinant RGR expression was detected by Western blot analysis, and functionality of the protein was tested by a [3H]all-trans-retinal binding assay.

RESULTS

RGR protein was detected in each cell type after transduction with recombinant virus and was not observed in untreated cells. RGR expression in ARPE-19 cells increased steadily for up to 10 days after transduction and was stable for at least 6 months. The transduced ARPE-19 cells produced approximately 100-fold higher amounts of RGR protein than the transduced COS-7 cells. When cell membranes from the ARPE-19 cells were incubated with [3H]all-trans-retinal, the chromophore bound specifically to the expressed protein. Uptake of [3H]all-trans-retinol into the ARPE-19 cells was followed by specific binding of radiolabeled retinoid to RGR.

CONCLUSIONS

Using a Lentivirus-derived gene delivery system, we were able to express high amounts of human RGR protein in the ARPE-19 human RPE cell line. The transduced ARPE-19 cells remain able to process all-trans-retinol, and the expressed protein is capable of binding to the all-trans-retinal chromophore. The Lentivirus-based expression of functional RGR can be used to study RGR in cultured cells and to test in vivo transduction of quiescent RPE cells.

Slow gating of gap junction channels and calmodulin

Certain COOH-terminus mutants of connexin32 (Cx32) were previously shown to form channels with unusual transjuctional voltage (V(j)) sensitivity when tested heterotypically in oocytes against Cx32 wild type. Junctional conductance (G(j)) slowly increased by severalfold or decreases to nearly zero with V(j) positive or negative, respectively, at mutant side, and V(j) positive at mutant side reversed CO(2)-induced uncoupling. This suggested that the CO(2)-sensitive gate might be a V(j)-sensitive slow gate. Based on previous data for calmodulin (CaM) involvement in gap junction function, we have hypothesized that the slow gate could be a CaM-like pore plugging molecule (cork gating model). This study describes a similar behavior in heterotypic channels between Cx32 and each of four new Cx32 mutants modified in cytoplasmic-loop and/or COOH-terminus residues. The mutants are: ML/NN+3R/N, 3R/N, ML/NN and ML/EE; in these mutants, N or E replace M105 and L106, and N replace R215, R219 and R220. This study also reports that inhibition of CaM expression strongly reduces V(j) and CO(2) sensitivities of two of the most effective mutants, suggesting a CaM role in slow and chemical gating.

Calmodulin directly gates gap junction channels

Cytosolic changes control gap junction channel gating via poorly understood mechanisms. In the past two decades calmodulin participation in gating has been suggested, but compelling evidence for it has been lacking. Here we show that calmodulin indeed is associated with gap junctions and plays a direct role in chemical gating. Expression of a calmodulin mutant with the N-terminal EF hand pair replaced by a copy of the C-terminal pair dramatically increases the chemical gating sensitivity of gap junction channels composed of connexin 32 and decreases their sensitivity to transjunctional voltage. The increased chemical gating sensitivity, most likely because of the higher overall Ca(2+) binding affinity of this mutant as compared with native calmodulin, and the decreased voltage sensitivity are only observed when the mutant is expressed before connexin 32. This indicates that the mutant, and by extension native calmodulin, must interact with connexin 32 before gap junctions are formed. Immunofluorescence data suggest further that this interaction leads to incorporation of native or mutant calmodulin into the connexon as an integral regulatory subunit.

Effect of the environment on alpha-Al2O3 (0001) surface structures

We report that calculating the Gibbs free energy of the alpha-Al2O3 (0001) surfaces in equilibrium with a realistic environment containing both oxygen and hydrogen species is essential for obtaining theoretical predictions consistent with experimental observations. Using density-functional theory we find that even under conditions of high oxygen partial pressure the metal-terminated surface is surprisingly stable. An oxygen-terminated alpha-Al2O3 (0001) surface becomes stable only if hydrogen is present on the surface. In addition, including hydrogen on the surface resolves discrepancies between previous theoretical work and experimental results with respect to the magnitude and direction of surface relaxations.

Chemical gating of gap junction channels

Chemical gating of gap junction channels is a complex phenomenon that may involve intra- and intermolecular interactions among connexin domains and a cytosolic molecule (calmodulin?) that may function as channel plug. This article focuses on the methodology we have employed for studying the molecular basis of chemical gating by lowered cytosolic pH. Our approach has combined molecular genetics and biophysics, using exposure to 100% CO(2) for assaying chemical gating efficiency. Chimeras of connexin 32 (Cx32) and connexin 38 (Cx38) and Cx32 mutants modified at residues of the cytoplasmic loop, the initial C-terminus domain, or both have been expressed in Xenopus oocytes, and channel expression and gating have been tested electrophysiologically by double voltage clamp. In addition, various channel forms, including homotypic, heterotypic, and heteromeric channel combinations, have been evaluated for chemical gating sensitivity.

Expression, purification, crystallization and preliminary x-ray data of Escherichia coli galactoside acetyltransferase

Crystals of galactoside acetyltransferase from Escherichia coli have been prepared from solutions of ammonium sulfate containing acetyl-CoA. These crystals diffract to at least 2.7 A resolution, belong to space group C222(1) and contain one copy of the trimeric enzyme in the asymmetric unit.

Is the chemical gate of connexins voltage sensitive? Behavior of Cx32 wild-type and mutant channels

Connexin channels are gated by transjunctional voltage (Vj) or CO2 via distinct mechanisms. The cytoplasmic loop (CL) and arginines of a COOH-terminal domain (CT1) of connexin32 (Cx32) were shown to determine CO2 sensitivity, and a gating mechanism involving CL-CT1 association-dissociation was proposed. This study reports that Cx32 mutants, tandem, 5R/E, and 5R/N, designed to weaken CL-CT1 interactions, display atypical Vj and CO2 sensitivities when tested heterotypically with Cx32 wild-type channels in Xenopus oocytes. In tandems, two Cx32 monomers are linked NH2-to-COOH terminus. In 5R/E and 5R/N mutants, glutamates or asparagines replace CT1 arginines. On the basis of the intriguing sensitivity of the mutant-32 channel to Vj polarity, the existence of a "slow gate" distinct from the conventional Vj gate is proposed. To a lesser extent the slow gate manifests itself also in homotypic Cx32 channels. Mutant-32 channels are more CO2 sensitive than homotypic Cx32 channels, and CO2-induced chemical gating is reversed with relative depolarization of the mutant oocyte, suggesting Vj sensitivity of chemical gating. A hypothetical pore-plugging model involving an acidic cytosolic protein (possibly calmodulin) is discussed.

Tropomyosin is localized in the nuclear matrix and chromosome scaffold of Physarum polycephalum

The nuclei and chromosomes were isolated from plasmodia of Physarum polycephalum. The nuclear matrix and chromosome scaffold were obtained after the DNA and most of the proteins were extracted with DNase I and 2 M NaCl. SDS-PAGE analyses revealed that the nuclear matrix and chromosome scaffold contained a 37 kD polypeptide which is equivalent to tropomyosin in molecular weight. Immunofluorescence observations upon slide preparations labeled with anti-tropomyosin antibody showed that the nuclear matrix and chromosome scaffold emanated bright fluorescence, suggesting the presence of the antigen in them. Immunodotting results confirmed the presence of tropomyosin in the nuclear matrix and chromosome scaffold. Immunoelectron microscopic observations further demonstrated that tropomyosin was dispersively distributed in the interphase nuclei and metaphase chromosomes.

Insights into the mechanism of domain closure and substrate specificity of glutamate dehydrogenase from Clostridium symbiosum

Comparisons of the structures of glutamate dehydrogenase (GluDH) and leucine dehydrogenase (LeuDH) have suggested that two substitutions, deep within the amino acid binding pockets of these homologous enzymes, from hydrophilic residues to hydrophobic ones are critical components of their differential substrate specificity. When one of these residues, K89, which hydrogen-bonds to the gamma-carboxyl group of the substrate l-glutamate in GluDH, was altered by site-directed mutagenesis to a leucine residue, the mutant enzyme showed increased substrate activity for methionine and norleucine but negligible activity with either glutamate or leucine. In order to understand the molecular basis of this shift in specificity we have determined the crystal structure of the K89L mutant of GluDH from Clostridium symbiosum. Analysis of the structure suggests that further subtle differences in the binding pocket prevent the mutant from using a branched hydrophobic substrate but permit the straight-chain amino acids to be used as substrates. The three-dimensional crystal structure of the GluDH from C. symbiosum has been previously determined in two distinct forms in the presence and absence of its substrate glutamate. A comparison of these two structures has revealed that the enzyme can adopt different conformations by flexing about the cleft between its two domains, providing a motion which is critical for orienting the partners involved in the hydride transfer reaction. It has previously been proposed that this conformational change is triggered by substrate binding. However, analysis of the K89L mutant shows that it adopts an almost identical conformation with that of the wild-type enzyme in the presence of substrate. Comparison of the mutant structure with both the wild-type open and closed forms has enabled us to separate conformational changes associated with substrate binding and domain motion and suggests that the domain closure may well be a property of the wild-type enzyme even in the absence of substrate.

Absorption Intensity of Stretching Overtone States of Silane and Germane

The band absorbance and line absorbance of R branch transitions are obtained from high-resolution Fourier transform measurement of silane and germane local mode overtones (n000), n = 1-5, under proper sample pressures and absorption lengths. The absorption coefficients of these overtones are derived by linear least-squares fitting. The relative intensities of overtones can be satisfactorily reproduced with the bond dipole model containing two adjustable parameters. Copyright 1998 Academic Press.

Molecular dissection of a basic COOH-terminal domain of Cx32 that inhibits gap junction gating sensitivity

Connexin32 (Cx32) mutants were studied by double voltage clamp in Xenopus oocytes to determine the role of basic COOH-terminal residues in gap junction channel gating by CO2 and transjunctional voltage. Replacement of five arginines with N (5R/N) or T residues in the initial COOH-terminal domain (CT1) of Cx32 enhanced CO2 sensitivity. The positive charge, rather than the R residue per se, is responsible for the inhibitory role of CT1, because mutants replacing the five R residues with K (5R/K) or H (5R/H) displayed CO2 sensitivity comparable to that of wild-type Cx32. Mutants replacing R with N residues four at a time (4R/N) showed that CO2 sensitivity is strongly inhibited by R215 and mildly by R219, whereas R220, R223, and R224 may slightly increase sensitivity. Neither the 5R/N nor the 4R/N mutants differed in voltage sensitivity from wild-type Cx32. The possibility that inhibition of gating sensitivity results from electrostatic interactions between CT1 and the cytoplasmic loop is discussed as part of a model that envisions the cytoplasmic loop of Cx32 as a key element of chemical gating.

Chemical gating of heteromeric and heterotypic gap junction channels

Gap junction channels contain two hemichannels (connexons), each being a connexin (Cx) hexamer. In cells expressing multiple connexins, heteromeric connexons are believed to form, whereas cell pairs expressing different connexins generate heterotypic channels. To define gating behavior of heteromeric and heterotypic channels, CO2-induced gating was tested in Xenopus oocyte pairs expressing Cx32, or 5R/N (Cx32 mutant), as well as in pairs in which one oocyte (mx) expressed a 50/50 mixture of Cx32 and 5R/N and the other either the mixture (mx), Cx32 (32) or 5R/n (R/N). In 5R/N, replacement of 5 C-terminus arginines with asparagines greatly increased CO2 sensitivity. In response to 3 and 15 min CO2 exposures, junctional conductance (Gj) decreased to 85% and 47%, in 32-32 pairs, and to 7% and 0.9%, in R/N-R/N pairs, respectively. In mx-mx and mix-32 pairs, Gj decreased to similar values (33% and 35%, respectively) with 15 min CO2. The sensitivity of mx-R/N pairs was similar to that of heterotypic 32-R/N pairs, as Gj dropped to 36% and 38%, respectively, with 3 min CO2. Monoheteromeric (mx-32 and mx-R/N) and biheteromeric (mx-mx) channels behaved as if Cx32 were dominant, suggesting that hemichannel sensitivity is not an average of the sensitivities of its connexin monomers. In contrast, heterotypic channels behaved as if the two hemichannels of a cell-cell channel had no influence on each other.

Determinants of substrate specificity in the superfamily of amino acid dehydrogenases

The subunit of the enzyme glutamate dehydrogenase comprises two domains separated by a cleft harboring the active site. One domain is responsible for dinucleotide binding and the other carries the majority of residues which bind the substrate. During the catalytic cycle a large movement between the two domains occurs, closing the cleft and bringing the C4 of the nicotinamide ring and the Calpha of the substrate into the correct positioning for hydride transfer. In the active site, two residues, K89 and S380, make interactions with the gamma-carboxyl group of the glutamate substrate. In leucine dehydrogenase, an enzyme belonging to the same superfamily, the equivalent residues are L40 and V294, which create a more hydrophobic specificity pocket and provide an explanation for their differential substrate specificity. In an attempt to change the substrate specificity of glutamate dehydrogenase toward that of leucine dehydrogenase, a double mutant, K89L,S380V, of glutamate dehydrogenase has been constructed. Far from having a high specificity for leucine, this mutant appears to be devoid of any catalytic activity over a wide range of substrates tested. Determination of the three-dimensional structure of the mutant enzyme has shown that the loss of function is related to a disordering of residues linking the enzyme's two domains, probably arising from a steric clash between the valine side chain, introduced at position 380 in the mutant, and a conserved threonine residue, T193. In leucine dehydrogenase the steric clash between the equivalent valine and threonine side chains (V294, T134) does not occur owing to shifts of the main chain to which these side chains are attached. Thus, the differential substrate specificity seen in the amino acid dehydrogenase superfamily arises from both the introduction of simple point mutations and the fine tuning of the active site pocket defined by small but significant main chain rearrangements.

Intersubunit communication in hybrid hexamers of K89L/A163G/S380A and C320S mutants of glutamate dehydrogenase from Clostridium symbiosum

The triple mutant K89L/A163G/S380A (inactive with glutamate but active with L-Nle and L-Met) and C320S (fully active with glutamate, entirely inactive with L-Nle and L-Met, and also lacking reactive cysteine) mutant of glutamate dehydrogenase (EC 1.4.1.2) of Clostridium symbiosum could be completely denatured by urea with the loss of structure and activity. The mutants denatured by urea could be reassociated to give stable hexamers with recovery of activity of approximately 67% by dilution in 0.1 M potassium phosphate buffer (pH 7.0) containing 2 mM NAD+. The native, urea-denatured, and renatured states of mutant enzymes were characterized by size exclusion chromatography on FPLC and native PAGE. Intersubunit hybrid hexamers containing five subunits of triple mutant and one subunit of C320S mutant were constructed by in vitro subunit hybridization followed by affinity chromatography. Kinetic analysis showed that a 5:1 hybrid hexamer, with only one C320S subunit able to bind NAD+ after DTNB modification, shows classical Michaelis-Menten kinetics with regard to NAD+. This contrasts with the apparent negative co-operativity shown by pure C320S hexamers and suggests that the interaction in NAD+ binding among subunits is eliminated in the hybrid. After removal of thionitrobenzoate, however, all of the subunits in the hybrid are able to bind NAD+. In this state the hybrid enzyme showed slight deviation from classical behavior with regard to NAD+, indicating reintroduction of some level of allosteric interaction. The hybrid hexamer also showed much reduced co-operativity with glutamate at pH 8.8, with a Hill coefficient of 3 for DTNB-treated hybrid (as compared to 5.2 for the pure C320S mutant) and 2.2 for the untreated hybrid. The fact that co-operativity in glutamate binding is not entirely eliminated correlates with evidence that the triple mutant subunits, though inactive toward glutamate, can nevertheless still bind this amino acid.

Positive charges of the initial C-terminus domain of Cx32 inhibit gap junction gating sensitivity to CO2

Gap junction channels close with CO2 exposure. To determine whether the carboxy-terminus (CT) of connexin32 (Cx32) participates in gating, the CO2 sensitivity of channels made of Cx32 or Cx32 mutants was studied by double voltage clamp. In Xanopus laevis oocytes expressing Cx32, junctional conductance (Gj) dropped to 85% and 47% of controls with 3- and 15-min CO2 exposures, respectively. In response to the 15-min exposure to CO2, pHi dropped to approximately 6.4 in 5-7 min and did not decrease further, even with 30-min exposures. CT deletion by 84% did not affect CO2 sensitivity, but replacement of five arginines (R215, R219, R220, R223, and R224) with asparagines (N) or threonines at the beginning of CT (CT1) in Cx32 or Cx32 deleted beyond residue 225 greatly enhanced CO2 sensitivity (with 3-min CO2 Gj dropped to approximately 8%). Partial R/N replacement resulted in intermediate CO2 sensitivity enhancement. R215 is a stronger inhibitor than R219-220, whereas R223-224 may diminish the inhibitory efficiency of R215 and R219-220. Therefore, positive charges of CT1 reduce the CO2 sensitivity of Cx32, whereas the rest (> 80%) of CT seems to play no role in CO2-induced gating. The role of presumed electrostatic interactions among Cx32 domains in CO2-induced gating is discussed.

[Clinical study on treatment of chronic aplastic anemia with busui shengxue capsule]

OBJECTIVE

To explore into the theoretical basis of Busui Shengxue Capsule (BSSXC) in treating chronic aplastic anemia (CAA).

METHODS

Applying the techniques of cell culture and FACS to observe the bone marrow mononuclear, cells of 35 cases CAA before and after treatment.

RESULTS

(1) BSSXC has the function of restoring the membrane receptors of IL-3, IL-6, IL-11 of hematopoietic stem cell. (2) The treatment effect of BSSXC is better than Western medicine. (3) In treatment group, to stimulate the hematopolietic stem cell with IL-3, IL-6, IL-11, the rate of cell colony forming unit and CD34+ cell were obviously different between Yang Deficiency type and Yin Deficiency type before treatment (P < 0.05). After treatment the difference between these two types was also obvious (P < 0.05).

CONCLUSION

BSSXC could improve the membrane receptor of hematopoietic stem cell acted by hematopoietic stimulating factors.

Alveolar echinococcosis: Em2plus-ELISA and Em18-western blots for follow-up after treatment with albendazole

Eleven cases of alveolar echinococcosis (Echinococcus multilocularis infection) with non-resectable lesions but treated with albendazole for 17 to 69 months were followed-up clinically and serologically for 4.5-11.5 years. Based on the clinical outcome and computerized tomography (CT) scanning, they were divided into 4 groups of 2 cured cases, 5 stabilized cases, 3 cases with recurrences, and one treatment failure. Forty-seven sequentially collected sera from the 11 cases were analysed by sequential enzyme-linked immunosorbent assay (ELISA) using Em2plus antigen (Em2plus-ELISA) and Western blotting to detect antibody response against Em18 (Em18-Western blots). The antibody levels in one of the cured and 2 of the stabilized cases fell below the cut-off level in the Em2plus-ELISA 4.5-6 years after effective treatment, whereas all other cases, including 2 of those with recurrences, showed large reductions initially but increased again during the follow-up period. Em18-Western blots of the 2 cured cases and 2 of the stabilized cases became negative. IgG subclasses with responses against Em18 which fell to zero included IgG1 (2), IgG3 (one) and IgG4 (one). All other cases showed no decrease in antibody response against Em18. There were, in general, reasonably reliable correlations between the success or failure of chemotherapy and antibody responses by Em2plus-ELISA and Em18-Western blots. These results suggest that both Em2plus-ELISA and Em18-Western blot are potentially useful in evaluating and predicting the efficacy of chemotherapy.

Antibody responses against Em18 and Em16 serodiagnostic markers in alveolar and cystic echinococcosis patients from northwest China

Western blot analysis was carried out in order to evaluate new serodiagnostic markers, Em18 and Em16, for differentiation of alveolar echinococcosis (AE) from cystic echinococcosis (CE) using 36 serum samples from hydatid patients from Xinjiang, China, where AE and CE are both endemic and one double infection case has been reported. All AE cases except one (5/6) who exhibited a calcified lesion and a single case of double infection showed antibody responses against Em18 and Em16. Some of CE patient sera (6/22) showed antibody response against Em16 except one who showed that against Em18. Analyses of IgG subclass responses against Em18 and Em16 were carried out using all serum samples showing antibody responses against Em18 and/or Em16 (seven CE, five AE, and one AE + CE) and additional samples of three CE and 22 AE from Sichuan, China. IgG4 was the most predominant antibody subclass. Em18 and Em16 were recognized by both IgG4 and IgG1 (in most cases) or by either IgG4 or IgG1 (in minor cases) or by IgG3 (in very rare cases). Neither Em18 nor Em16 was recognized by IgG2 antibodies. The usefulness of Em18 and Em16 as potential new markers for serological differentiation of human AE and CE, respectively, is discussed.

Immunodiagnosis of alveolar echinococcosis by enzyme-linked immunosorbent assay using a partially purified Em18/16 enriched fraction

An improved enzyme-linked immunosorbent assay (ELISA) system using partially purified Eml8/16 enriched fraction (PP-Em18/16) prepared by isoelectric focusing was evaluated for serodiagnosis of alveolar echinococcosis (AE). The PP-Em18/16-ELISA was compared with Em2plus-ELISA by using sera from AE and cystic echinococcosis (CE) patients in China, where both AE and CE are endemic; sera from CE patients in Australia, where only CE exists; and sera from patients with cysticercosis, paragonimiasis, or sparganosis in Korea, where no indigenous AE or CE exists. We used Em2plus-ELISA as a standard ELISA and found 24.6% (17 of 69 specimens) cross-reactivity with sera from CE. Furthermore, some of the sera from paragonimiasis, sparganosis, and cysticercosis patients were also cross-reactive in the Em2plus-ELISA. When we tested for similar cross-reactivity in the same sera from CE patients by PP-Em18/16-ELISA (23.2%, 16 of 69), it became evident that the specificity of the PP-Em18/16-ELISA was better than that of the Em2plus-ELISA, since no sera from patients with the examined parasitic diseases except CE showed cross-reactivity. Some CE patients from China showed exceptionally high levels of antibody in comparison with those of CE patients from Australia, where no AE occurs. It is speculated that these patients with strongly positive cases of CE from China may have been exposed to both species of Echinococcus.

Connexin 32/38 chimeras suggest a role for the second half of inner loop in gap junction gating by low pH

Gap junction channels are regulated by gates that close with cytosolic acidification and transjunctional voltage (Vj). For identifying the connexin (Cx) domain(s) involved in channel gating, CO2 and Vj sensitivities of channels made of Cx38, Cx32, Cx32/Cx38 chimeras, and Cx32 mutants were studied in Xenopus oocyte pairs. Recently, we have reported that Cx38 is more sensitive to CO2 and Vj than Cx32 because of differences in the Cx inner loop. To identify the responsible inner loop domain, chimeras of Cx32/Cx38 in which the first (I1) or the second (I2) half of the inner loop of Cx38 replaced that of Cx32 and I2 mutants of Cx32 were tested. The chimera Cx32/Cx38I2 (Cx32 with I2 of Cx38) was like Cx38 in CO2 sensitivity but like Cx32 in Vj sensitivity. Cx32/Cx38I1 (Cx32 with I1 of Cx38) did not express channels. Of the three Cx32 mutants, Cx32-VH/IR VH of Cx32 replaced with IR of Cx38) and Cx32-WW/MC WW of Cx32 replaced with MC of Cx38) were like Cx32 in both CO2 and Vj sensitivity, whereas Cx32-S*T/Q*P (S*T of Cx32 replaced with Q*P of Cx38) was closer to Cx38 in CO2 sensitivity but behaved like Cx32 in Vj gating. The data suggest that I1 and I2 contain domains relevant for Vj and CO2 gating, respectively.

Positive cooperativity with Hill coefficients of up to 6 in the glutamate concentration dependence of steady-state reaction rates measured with clostridial glutamate dehydrogenase and the mutant A163G at high pH

Glutamate dehydrogenases from many sources display nonclassical kinetic behavior suggestive of allosteric interaction among the six subunits of the hexamer. A three-dimensional structure now potentially offers a framework for explaining the basis of such behavior in clostridial glutamate dehydrogenase, and this paper offers evidence of extreme, all-or-none cooperativity in the binding of glutamate by this enzyme. A site-directed mutant of clostridial glutamate dehydrogenase in which Ala163 in the glutamate binding site is replaced by glycine displays a markedly sigmoid dependence of reaction rate on glutamate concentration (S0.5 = 200 mM), with a Hill coefficient of 3.4 when assayed at pH 10.5 with 1 mM NAD+. Under the same conditions the wild-type enzyme gave no measurable rate with glutamate concentrations in the range normally used for kinetics (0-100 mM) but gave a steep rise in reaction rate from 600 to 1200 mM glutamate. At pH 9.0, where the wild-type enzyme has previously been shown to be "inactive" in a standard assay, a study extending to much higher glutamate concentrations again revealed a sigmoid dependence, with a Hill coefficient of 5.4 and an S0.5 at 150 mM glutamate. With the mutant A163G the apparent cooperativity was less, with a Hill coefficient of 2.3, and the affinity for glutamate was higher, with S0.5 of 7 mM. Both proteins gave normal hyperbolic dependence on glutamate concentration at pH 7 and pH 8. At pH 9 and with saturating glutamate, both enzymes showed a hyperbolic dependence of the rate on NAD+ concentration. The NAD+ concentration, however, affected the observed degree of cooperativity with varied glutamate.(ABSTRACT TRUNCATED AT 250 WORDS)

Alteration of the amino acid substrate specificity of clostridial glutamate dehydrogenase by site-directed mutagenesis of an active-site lysine residue

Two residues, K89 and S380, thought to interact with the gamma-carboxyl group of the substrate L-glutamate, have been altered by site-directed mutagenesis of clostridial glutamate dehydrogenase (GDH). The single mutants K89L and S380V and the combined double mutant K89L/S380V were constructed. All three mutants were satisfactorily overproduced in soluble form. However, only the K89L mutant was retained by the dye column normally used in purifying the wild-type enzyme. All three mutant enzymes were purified to homogeneity and tested for substrate specificity with 24 amino acids. The single mutant S380V showed no detectable activity. The alternative single mutant K89L showed an activity towards L-glutamate that was decreased nearly 2000-fold compared with wild-type enzyme, whereas the activities towards the monocarboxylic substrates alpha-aminobutyrate and norvaline were increased 2- to 3-fold. A similar level of activity was obtained with methionine (0.005 U/mg) and norleucine (0.012 U/mg), neither of which give any activity with the wild-type enzyme under the same conditions. The double mutant showed decreased activity with all substrates compared with the wild-type GDH. In view of its novel activities, the K89L mutant was investigated in greater detail. A strictly linear relationship between reaction velocity and substrate concentration was observed up to 80 mM L-methionine and 200 mM L-norleucine, implying very high Km values. Values of kcat/Km for L-methionine and L-norleucine were 6.7 x 10(-2) and 0.15 s-1 M-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of the reactive cysteine in clostridial glutamate dehydrogenase by site-directed mutagenesis and proof that this residue is not strictly essential

Cys320 of clostridial glutamate dehydrogenase, a residue close to the coenzyme binding site, has been replaced by serine. The mutant enzyme was successfully overproduced and purified by using the normal protocol for the wild-type enzyme and also behaved indistinguishably from wild-type enzyme on native and SDS-PAGE. The specific activity was significantly enhanced in assays at both pH 7 (+90%) and pH 8 (+38%). Detailed initial-rate kinetics revealed that at pH 7 this increase was mainly attributable to a higher maximum rate, since the Km values for both substrates were marginally increased. In the mutant enzyme the inactivating reaction with DTNB that characterizes the wild-type enzyme is completely eliminated. This proves that inactivation of the wild-type enzyme is due to modification of Cys320, that nevertheless Cys320 is not strictly essential for catalytic activity and that the remaining cysteine residue at position 144 is inaccessible to DTNB. Provision of an engineered subunit with a correct native structure but with its DTNB titre decreased from 1 to 0 mol/mol now offers a valuable tool for counting subunits in hybrid oligomers.

The catalytic role of aspartate in the active site of glutamate dehydrogenase

A putative catalytic aspartyl residue, Asp-165, in the active site of clostridial glutamate dehydrogenase has been replaced with serine by site-directed mutagenesis. The mutant enzyme is efficiently overexpressed in Escherichia coli as a soluble protein and can be successfully purified by the dye-ligand chromatographic procedure normally employed for the wild-type enzyme. By several criteria, including circular dichroism spectrum, sulphydryl reactivity with Ellman's reagent, crystallization and mobility in non-denaturing electrophoresis, the enzyme appears to be correctly folded. NAD+ protects the D165S mutant against modification by Ellman's reagent, suggesting unimpaired binding of coenzyme. In standard assays the specific activity is decreased 10(3)-fold in the reductive amination reaction and 10(5)-fold for oxidative deamination. Kinetic studies show that apparent Km values for NADH and 2-oxoglutarate are almost unchanged. The large reduction in the reaction rate coincides with a weakening of the affinity for ammonium ion (Km > 300 mM, compared with 60 mM for the wild-type). The data are entirely consistent with the direct involvement of D165 in catalysis rather than in the binding of coenzyme or 2-oxoglutarate.

[Carbohydrate intolerance and pregnancy outcome]

Fifty gram oral glucose challenge test (50g GCT) was performed, as a screening test of diabetes mellitus (DM), in 289 pregnant women, and further, a 75g oral glucose tolerance test (OGTT) was done in those women with glucose level > 7.78 mmol/L. The results showed that 49 women had a glucose level > 7.78 mmol/L (16.96%), among whom 15 (5.19%) were identified as having gestational impaired glucose tolerance (GIGT), and 5 (1.73%) had gestational diabetes mellitus (GDM) as diagnosed by 75g OGTT. The prevalence of PIH, premature rupture of membrane, fetal macrosomia, cesarean section, perinatal morbidity were higher in GIGT and GDM mothers and there was a positive correlation between glucose level of 50g GCT and the birth weight of newborns. It suggested that 50g GCT may be a preferable screening test for GDM since it is simple and cheap with high sensitivity and specificity.

[Computerized tomography of liver in alveolar echinococcosis treated with albendazole]

Eleven cases of alveolar echinococcosis were examined by using computerized tomographic (CT) scanning of liver 2-7 years after long-term continuous albendazole therapy. In seven cases the hepatic lesion was almost completely calcified and cured in three cases incomplete calcification of the peripheral margin of the hepatic lesion was observed. CT scanning of the remaining in effective case showed active lesion with heterogenous hypodense areas in the liver without calcification on the peripheral margin. Long-term continuous albendazole therapy can be lethal to the parasite.

Differential serodiagnosis of alveolar and cystic hydatid disease in the People's Republic of China

Western blot analysis was carried out using crude antigens of Echinococcus multilocularis and 33 serum samples from the People's Republic of China to differentiate patients with alveolar hydatid disease (AHD) with active lesions from those with inactive lesions, those with other parasitoses including cystic hydatid disease (CHD), and healthy persons. This analysis was based on the detection of antibody responses against two polypeptides, Em18 and Em16, which appeared to be species specific and good indices for the differentiation of AHD with active lesions from AHD with inactive lesions. Twenty-one of the 33 samples showed antibody responses against Em18 and/or Em16. Fifteen were antibody-positive for both Em18 and Em16, five were antibody-positive for Em18 only, and one was antibody-positive for Em16 only. Of the subjects from which the 33 samples were obtained, 12 patients had AHD with active lesions, two had AHD, but their lesions were resolved by surgical resections, 14 had CHD with active lesions, and five were apparently healthy people. Western blot analysis confirmed all 14 cases of AHD, three of the 14 cases of CHD, and showed that one of the five apparently healthy individuals had a positive serologic response for AHD. This apparently healthy person with a positive serologic response for AHD by Western blot analysis was found to be positive for the disease on re-examination. Thus, Western blot analysis based on the antibody responses against Em18 and Em16, especially against Em18, was extremely reliable for the detection of AHD with active lesions, although it failed to differentiate two of the 14 patients with CHD.(ABSTRACT TRUNCATED AT 250 WORDS)

Levo-praziquantel versus praziquantel in experimental and clinical treatment of schistosomiasis japonica

Levo-praziquantel is the left isomer of racemic praziquantel. Animal experiments showed that it is an active component of schistosomicidal activity, while dextro-praziquantel is almost ineffective. Clinical trials in three endemic areas of Schistosomiasis japonica indicated that the therapeutic efficacy of levo-praziquantel is superior to racemic praziquantel. Pharmacokinetic and pharmacodynamic activities of the stereoselectivity of praziquantel isomers (enantiomers) are discussed.