Antigenic relationships among five reovirus-like (RVL) agents by complement fixation (CF) and development of new substitute CF antigens for the human RVL agent of infantile gastroenteritis.

The human reovirus-like (HRVL) agent, Nebraska calf diarrhea virus (NCDV), epizootic diarrhea of infant mice (EDIM) virus, simian agent (SA)-11, and the "O" (offal) agent were found to be similar, if not identical, in reciprocal complement fixation (CF) tests employing hyperimmune animal sera. In addition, in CF tests with paired sera from 35 diarrhea patients who shed the HRVL agent, 74% developed serologic evidence of infection with the HRVL antigen, 43% with NCDV, 51% with EDIM virus, 57% with SA-11, and 71% with the "O" agent. Thus, in addition to the NCDV, which had previously been described as a suitable substitute CF antigen for the HRVL agent, the SA-11, "O", and EDIM viruses may also be utilized as substitute antigens for the HRVL agent. However, the "O" agent appears to be the most efficient of the four substitute CF antigens and thus should be used preferentially when the HRVL agent is not available. The "O" agent was about as efficient as the HRVL agent and significantly more efficient than the NCDV for detecting seroresponses. The greatest efficiency for detecting infection with the HRVL agent resulted when sera were tested with both the HRVL and "O" agents as 31 (89%) of the patients developed serologic evidence of infection with one or both antigens. The finding of additional substitute CF antigens for the HRVL agent may have implications in the immunoprophylaxis against human disease.     

Effect of redox agents on the non-electrolyte isotonic concentrations and on the equivalent pore radius of skeletal muscles of the frog

Oxidizing and/or reducing agents inversely influence the alterations in the speed of mass changes (dw/dt) due to osmotic perturbations: an oxidizing agent increases while a reducing agent decreases it. The values for isotonic concentration (Ciso) increased for all of the tested non-electrolytes in the presence of an oxidizing agent, while decreased in the presence of a reducing one. The Staverman's reflection coefficient values (sigma) showed changes opposite in direction, so that the direct correlation between the size of test molecules and sigma values remained unchanged. An oxidizing agent increases and a reducing agent decreases the equivalent pore radius (EPR).     

化学-生物发酵联用技术对稻草腐熟的效果及红外光谱研究

采用傅立叶变换红外光谱(FTIR),研究了化学—生物联用处理对稻草腐熟的影响．结果表明,稻草经各化学—生物联用处理7d,其腐熟效果均比对照好．其中化学熟化剂A-生物熟化剂A联用处理后,稻草颜色暗褐色,容易折断,明显腐熟．FTIR分析表明,经处理后稻草的酚羟基、醇羟基和甲基含量降低,脂肪族化合物部分降解,芳构化成分增多,尤其是取代芳环增多,氧化缩合作用增强,加快了稻草的腐殖化进程．比较各熟化剂及其配合对稻草的腐熟效果表明,化学熟化剂A>化学熟化剂B。生物熟化剂A>生物熟化剂B>生物熟化剂C,其中化学熟化剂A-生物熟化剂A联用处理对稻草腐熟效果最好．     

An efficient preparation of polyanionic affinity agent and its evaluation for the measurement of glycated hemoglobin

An efficient method was developed for the preparation of polyanionic affinity agent (3), a key component in the measurement of glycated hemoglobin (GHb). Glycated hemoglobin is an important clinical marker for diagnosis of patients with diabetes and useful to monitor the management of disease. The affinity agent (3) was prepared based on coupling reaction between poly(acrylic acid) (1) and 3-aminophenylboronic acid (2) in water. The critical features of this polymeric affinity agent (3), such as size, boronic acid incorporation ratio and concentration, on the measurement of glycated hemoglobin were evaluated. It was found that the agent (3) prepared using poly(acrylic acid) (1) with 225 kDa molecular weight gave optimal GHb measurement. The performance test results demonstrated that the boronic acid incorporation ratio and concentration of affinity agent (3) play a critical role in the assay and determines the precision of glycated hemoglobin measurement.     

PEG-g-poly(GdDTPA-co-L-cystine): a biodegradable macromolecular blood pool contrast agent for MR imaging

Biodegradable PEGylated Gd-DTPA l-cystine copolymers, PEG-g-poly(GdDTPA-co-l-cystine), were prepared and tested as a blood pool contrast agent in mice. The biodegradable macromolecular agent was designed to be broken down into smaller Gd complexes by endogenous thiols via the disulfide-thiol exchange reaction to facilitate the clearance of Gd complexes after the contrast-enhanced MRI examination. Gd-DTPA l-cystine copolymers were synthesized by condensation polymerization of l-cystine and DTPA-dianhydride in water followed by chelating with Gd(OAc)(3). MPEG-NH(2) (MW = 2000) was then conjugated to the polymeric backbone in different ratios. The macromolecular contrast agent was readily degraded with the incubation of l-cysteine. It also demonstrated superior contrast enhancement in the heart and blood vessels as compared to a low molecular weight control agent, Gd-(DTPA-BMA). At 1 h postcontrast, the PEGylated macromolecular agent still showed prominent enhancement, while little contrast enhancement was detectable in the blood pool by the control agent. PEG-g-poly(GdDTPA-co-l-cystine) shows promise as an MR blood pool imaging agent.     

Description of a Viral Agent Found in Blood Obtained from Patients with Infectious Hepatitis

A small, double-stranded deoxyribonucleic acid viral agent (agent Y) has been found in blood from patients with infectious hepatitis. The agent was propagated in chimpanzee liver tissue culture which had been grown and maintained on unheated agamma calf serum. A causal relationship between this agent and the occurrence of human disease cannot be determined from the data presented.     

Prion interference with multiple prion isolates

Co-inoculation of prion strains into the same host can result in interference, where replication of one strain hinders the ability of another strain to cause disease. The drowsy (DY) strain of hamster-adapted transmissible mink encephalopathy (TME) extends the incubation period or completely blocks the hyper (HY) strain of TME following intracerebral, intraperitoneal or sciatic nerve routes of inoculation. However, it is not known if the interfering effect of the DY TME agent is exclusive to the HY TME agent by these experimental routes of infection. To address this issue, we show that the DY TME agent can block hamster-adapted chronic wasting disease (HaCWD) and the 263K scrapie agent from causing disease following sciatic nerve inoculation. Additionally, per os inoculation of DY TME agent slightly extends the incubation period of per os superinfected HY TME agent. These studies suggest that prion strain interference can occur by a natural route of infection and may be a more generalized phenomenon of prion strains.     

MR contrast agent composed of cholesterol and peptide nucleic acids: Design,synthesis and cellular uptake

A new mRNA targeting contrast agent consisting of three main functional domains, (i) gadolinium based magnetic resonance reporter part, (ii) antisense peptide nucleic acids targeted to mRNA, and (iii) cholesterol as the delivery vector, was developed and synthesized. The new contrast agent showed efficient cellular uptake and significant contrast enhancement at very low labeling concentrations (0.5 μM). However, after uptake into cells the agent was located predominantly in endosomes like a similar cell penetrating peptide conjugated probe. Our results indicate that this newly developed contrast agent could be used for the labeling of cells for optical as well as magnetic resonance imaging.     

A scientific approach to agent selection

Abstract  The prioritisation of potential agents on the basis of likely efficacy is an important step in biological control because it can increase the probability of a successful biocontrol program, and reduce risks and costs. In this introductory paper we define success in biological control, review how agent selection has been approached historically, and outline the approach to agent selection that underpins the structure of this special issue on agent selection. Developing criteria by which to judge the success of a biocontrol agent (or program) provides the basis for agent selection decisions. Criteria will depend on the weed, on the ecological and management context in which that weed occurs, and on the negative impacts that biocontrol is seeking to redress. Predicting which potential agents are most likely to be successful poses enormous scientific challenges. 'Rules of thumb', 'scoring systems' and various conceptual and quantitative modelling approaches have been proposed to aid agent selection. However, most attempts have met with limited success due to the diversity and complexity of the systems in question. This special issue presents a series of papers that deconstruct the question of agent choice with the aim of progressively improving the success rate of biological control. Specifically they ask: (i) what potential agents are available and what should we know about them? (ii) what type, timing and degree of damage is required to achieve success? and (iii) which potential agent will reach the necessary density, at the right time, to exert the required damage in the target environment?     

Use of hydroxyapatite-coasted glass beads for preclinical testing of potential antiplaque agents.

Methods for rapid preclinical testing of antiplaque agents in vitro using hydroxyapatite (HT)-coated glass beads are described. The assays developed could reliably detect (i) prevention of growth in the culture fluid or on the HT surfaces, (ii) the effect of transient exposure of a bactericidal agent on the viability of cells in a preformed bacterial mat, (iii) reversible adsorption of a bactericidal agent on an HT surface, and (iv) the ability of an agent to inhibit adsorption of Streptococcus sanguis to an HT surface or to salivary proteins adsorbed to an HT surface.     

Formation of taste aversions in the rat

The presence of correlation between the initial attitude of animals to a certain taste agent and the intensity of conditioned taste aversion (CTA) after LiCl poisoning was studied in nonlineal male white rats. 4 types of behavioural reactions were revealed: 1) the nonspecific inhibitory reaction to the situation in which CTA was elaborated; 2) specific associative-adaptive connection of CTA with the taste agent used (0,1% saccharine solution); 3) complex reaction consisting of the two first ones; 4) the same drinking behaviour as that before CTA elaboration. Moreover, a correlation was found between the initial attitude of animals to certain taste agent and the intensity of CTA after pairing of this agent with subsequent poisoning.     

Analyses of frequency of infection, specific infectivity, and prion protein biosynthesis in scrapie-infected neuroblastoma cell clones.

Scrapie, a spongiform encephalopathy of sheep and goats, is caused by a poorly understood transmissible agent in which no nucleic acid has been conclusively identified. Biochemical characterization of agent derived from animal tissues has not been precise because of the tenacious association of the agent with tissue components. As an approach toward obtaining homogeneous preparations of agent generated in vitro, we cloned scrapie-infected neuroblastoma cells. By frequency analysis, nearly every cell in expanded cultures contained scrapie agent. We also analyzed cell-dose infectivity relationships and developed a standard curve which allowed various cultures to be compared. Since a proteinase K (PK)-resistant form of a protein designated prion protein (PrP) has been found in partially purified preparations of scrapie agent from infected animal spleens and brains, we sought to identify this protein in cell cultures. No PK-resistant PrP was found in infected or uninfected cultures, although the PK-sensitive PrP was readily detected. These results suggested that PK-resistant PrP may not be an essential component of the infectious scrapie agent.     

Role of the GALT in scrapie agent neuroinvasion from the intestine

Following oral exposure, some transmissible spongiform encephalopathy (TSE) agents accumulate first upon follicular dendritic cells (FDCs) in the GALT. Studies in mice have shown that this accumulation is obligatory for the efficient delivery of the TSE agent to the brain. However, which GALTs are crucial for disease pathogenesis is uncertain. Mice deficient in specific GALT components were used here to determine their separate involvement in scrapie agent neuroinvasion from the intestine. In the combined absence of the GALTs and FDCs (lymphotoxin (LT)alpha(-/-) mice and LTbeta(-/-) mice), scrapie agent transmission was blocked. When FDC maturation was induced in remaining lymphoid tissues, mice that lacked both Peyer's patches (PPs) and mesenteric lymph nodes (wild-type (WT)-->LTalpha(-/-) mice) or PPs alone (WT-->LTbeta(-/-) mice) remained refractory to disease, demonstrating an important role for the PPs. Although early scrapie agent accumulation also occurs within the mesenteric lymph nodes, their presence in WT-->LTbeta(-/-) mice did not restore disease susceptibility. We have also shown that isolated lymphoid follicles (ILFs) are important novel sites of TSE agent accumulation in the intestine. Mice that lacked PPs but contained numerous FDC-containing mature ILFs succumbed to scrapie at similar times to control mice. Because the formation and maturation status of ILFs is inducible and influenced by the gut flora, our data suggest that such factors could dramatically affect susceptibility to orally acquired TSE agents. In conclusion, these data demonstrate that following oral exposure TSE agent accumulation upon FDCs within lymphoid tissue within the intestine itself is critically required for efficient neuroinvasion.     

Proteolysis of rabbit immunoglobulin M by papain (Short Communication)

1. Digestion of rabbit immunoglobulin M (IgM) by papain for 5h, in the absence of reducing agent, gives Fabmu and Fc(5)mu fragments in high yield. Shorter periods give fragment Fc(5)mu with one or more Fabmu fragments still attached. 2. Reducing agent in the absence of a denaturant cleaves rabbit IgM into half-subunits, each containing one mu chain and one light chain. Digestion by papain in the presence of such a reducing agent destroys the Fcmu domains.     

Assessment of atherosclerotic plaques in the rabbit abdominal aorta with interleukin-8 monoclonal antibody-targeted ultrasound microbubbles

In this study, we aimed to prepare a neovascularization-relevant inflammatory cytokine-targeted ultrasound contrast agent and apply it in the ultrasound imaging of atherosclerotic plaque. An interleukin-8 (IL-8) monoclonal antibody was conjugated to SonoVue microbubbles using the N-succinimidyl-3-(2-pyridyldithio)propionate cross-linking method. Then, a prepared IL-8-targeted contrast agent was used for contrast-enhanced ultrasound (CEU) to detect rabbit abdominal aorta atherosclerotic plaque and to investigate the imaging characteristics of atherosclerotic plaque with the contrast agent. We found that an IL-8 monoclonal antibody can be successfully coupled to SonoVue microbubbles with stable biological characteristics. CEU with this IL-8-targeted contrast agent can increase the atherosclerotic plaque detection sensitivity, with stronger echo, so that three more plaques were detected compared with using non-targeted SonoVue microbubbles. Thus, an inflammatory cytokine-targeting ultrasound contrast agent carrying IL-8 monoclonal antibody can provide unique advantages for researching the characteristics of atherosclerotic plaque.     

Rapid spread agents may impair biological control in a tritrophic food web with intraguild predation

The augmentation of natural enemies against agricultural pests is a common tactic undertaken to minimize crop damage without the use of chemical pesticides. Failures of this strategy may result from (i) Allee effects acting on biological control agent; (ii) trophic interactions between the released control agent and native species in the local ecosystem; (iii) excessively rapid spreading agents. To investigate the interplay of these mechanisms in pest biocontrol efficiency in the context of intraguild predation (IGP), we develop a one-dimensional dynamical model of a spatial, tritrophic food web with intraguild predation. We show that the agent’s diffusivity (i.e., agent’s dispersal speed), and intraguild predator’s addition of alternative food sources are important factors in determining the success or failure of pest biocontrol. These results are obtained for spatially explicit models by considering the speed of dispersal of the control agent and the pest. Feedback from theoretical models as the one constructed in this work can provide useful guidelines for practitioners in biological control.     

Reducing agents affect inhibitory activities of compounds: results from multiple drug targets

High-throughput screening (HTS) of large compound libraries has become a commonly used method for the identification of drug leads, and nonphysiological reducing agents have been widely used for HTS. However, a comparison of the difference in the HTS results based on the choice of reducing agent used and potency comparisons of selected inhibitors has not been done with the physiological reducing agent reduced glutathione (GSH). Here, we compared the effects of three reducing agents-dithiothreitol (DTT), β-mercaptoethanol (β-MCE), and tris(2-carboxyethyl)phosphine (TCEP)-as well as GSH against three drug target proteins. Approximately 100,000 compounds were computationally screened for each target protein, and experimental testing of high-scoring compounds (~560 compounds) with the four reducing agents surprisingly produced many nonoverlapping hits. More importantly, we found that various reducing agents altered inhibitor potency (IC(50)) from approximately 10 μM with one reducing agent to complete loss (IC(50)>200 μM) of inhibitory activity with another reducing agent. Therefore, the choice of reducing agent in an HTS is critical because this may lead to the pursuit of falsely identified active compounds or failure to identify the true active compounds. We demonstrate the feasibility of using GSH for in vitro HTS assays with these three target enzymes.     

Reaction between imidazolineoxil N-oxide (carboxy-ptio) and nitric oxide released from cultured endothelial cells: Quantitative measurement of nitric oxide by ESR spectrometry

The performance of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide for the monitoring agent of nitric oxide was investigated. The agent (125–500 μM) was mixed with equal volume of nitric oxide solution, and aliquots of the mixture were applied to ESR spectroscopy. ESR spectra of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl, a product of the agent reacted with nitric oxide, were observed. A linear relationship was observed between the amplitude of the signal and concentrations of nitric oxide up to 80 μM. Endothelial cells cultured on microcarries were packed in a column, perfused with Krebs solutions and the effluent was mixed to the agent. The same ESR spectra were obtained and amplitude of the signal was increased by bradykinin (3–300nM), decreased by preincubation of N^G-monomethyl-L-arginine (3–100 μM) and reversed by following incubation of L-arginine (100 μM).     

Some applications of a chiral fluorometric reagent, (S)-TBMB carboxylic acid

Molecular design and applications of a fluorometric chiral agent, (S)-TBMB carboxylic acid, are briefly reviewed. The agent, possessing an asymmetric 1,3-benzodioxole skeleton, was designed as a novel class of chiral agent that functions also as a benzoate chromophore for exciton chirality CD methods. The utility of this agent has been demonstrated in an application to determine enantiomeric amino acids, acyl-sn-glycerols, glycosyl-sn-glycerols, and other chiral alcohols and amines.