Clinical trials of efficacy of praziquantel horse paste 9% against tapeworms and its safety in horses

The aim of this study with horses and a few ponies naturally infected with tapeworms was to confirm in clinical trials the efficacy and safety of a praziquantel horse paste 9%. The field trials were conducted in 1997 and 1998 in Canada, France, Germany and New Zealand. A secondary aim of the study in Canada was to determine if a 24h post-treatment fecal sample provides the best estimate of the prevalence of tapeworms in horses when using a fecal examination technique. Fecal samples were taken from each of 1062 animals at least three times pre-treatment (PRT). In Canada, fecal samples were examined using the Cornell-Wisconsin centrifugal flotation technique, and in France, Germany and New Zealand using a centrifugation/flotation technique. In each trial, the animals were randomized into two treatment groups: praziquantel horse paste 9% at 1mg/kg body weight (BW) and untreated. Fecal samples were taken from each animal nine times post-treatment and over a period of 5 weeks. In Canada, a fecal sample was taken also at 24h after treatment. Personnel examining the samples were "blinded" to treatment groups. On the day of treatment, each treated animal was examined for adverse reactions to the paste 10min after treatment and then hourly for 4h. Thereafter, each animal was examined once daily for 5 weeks. In Canada, Germany and New Zealand, the only tapeworm egg found was Anoplocephala perfoliata. In France, A. perfoliata was the most common species and a few animals had A. magna and Paranoplocephala mamillana. The prevalence of A. perfoliata among animals sampled in Canada, France, Germany and New Zealand was 51.8, 34.4, 13.1 and 26.2%, respectively. A total of 248 animals were treated with the praziquantel paste and all except one accepted it readily. There were 292 animals completing the study, 219 treated and 73 untreated. In Canada, Germany and New Zealand, the efficacy of the praziquantel horse paste 9% against A. perfoliata was 100%. In France, the efficacy against A. perfoliata, A. magna and P. mamillana was 90.9, 100 and 100%, respectively. The best estimate of prevalence for A. perfoliata in a herd was derived from fecal samples taken 24h after treatment. At 24h, 22 of 23 treated horses were positive, whereas on any day pre-treatment fewer horses were positive. Adverse reactions observed were mild to moderate colic and in only two treated horses.     

Virtual international experiences in veterinary medicine: an evaluation of students' attitudes toward computer-based learning

While many studies have evaluated whether or not factual information can be effectively communicated using computer-aided tools, none has focused on establishing and changing students' attitudes toward international animal-health issues. The study reported here was designed to assess whether educational modules on an interactive computer CD elicited a change in veterinary students' interest in and attitudes toward international animal-health issues. Volunteer veterinary students at seven universities (first-year students at three universities, second-year at one, third-year at one, and fourth-year at two) were given by random assignment either an International Animal Health (IAH) CD or a control CD, ParasitoLog (PL). Participants completed a pre-CD survey to establish baseline information on interest and attitudes toward both computers and international animal-health issues. Four weeks later, a post-CD questionnaire was distributed. On the initial survey, most students expressed an interest in working in the field of veterinary medicine in another country. Responses to the three pre-CD questions relating to attitudes toward the globalization of veterinary medicine, interest in foreign animal disease, and inclusion of a core course on international health issues in the veterinary curriculum were all positive, with average values above 3 (on a five-point scale where 5 represented strong agreement or interest). Almost all students considered it beneficial to learn about animal-health issues in other countries. After students reviewed the IAH CD, we found a decrease at four universities, an increase at one university, and no change at the remaining two universities in students' interest in working in some area of international veterinary medicine. However, none of the differences was statistically significant.     

Early infections by myxoma virus of young rabbits (Oryctolagus cuniculus) protected by maternal antibodies activate their immune system and enhance herd immunity in wild populations

The role of maternal antibodies is to protect newborns against acute early infection by pathogens. This can be achieved either by preventing any infection or by allowing attenuated infections associated with activation of the immune system, the two strategies being based on different cost/benefit ratios. We carried out an epidemiological survey of myxomatosis, which is a highly lethal infectious disease, in two distant wild populations of rabbits to describe the epidemiological pattern of the disease. Detection of specific IgM and IgG enabled us to describe the pattern of immunity. We show that maternal immunity attenuates early infection of juveniles and enables activation of their immune system. This mechanism associated with steady circulation of the myxoma virus in both populations, which induces frequent reinfections of immune rabbits, leads to the maintenance of high immunity levels within populations. Thus, myxomatosis has a low impact, with most infections being asymptomatic. This work shows that infection of young rabbits protected by maternal antibodies induces attenuated disease and activates their immune system. This may play a major role in reducing the impact of a highly lethal disease when ecological conditions enable permanent circulation of the pathogen.     

Harvesting marine microalgae species by chitosan flocculation

Marine microalgae are still an important larval feeding source. One of the most promising harvesting techniques of the algae produced appears to be chemical flocculation. We report results obtained with chitosan flocculation of five marine species of microalgae of importance to mariculture (Skeletonema costatum, Dunaliella tertiolecta, Thalassiosira nordenskoldii, Chlorella sp. and Thalassionema sp.). The algae were grown in the laboratory in 20-liter batch cultures under normal conditions in artificial seawater. Without pH control, a 100% flocculation efficiency was reached at fairly high chitosan concentrations (above 40 mg liter⁻¹). When the final pH was adjusted to around 7·8–8·0, a 100% flocculation efficiency was obtained with chitosan concentrations of 40 mg liter⁻¹ or more. However, when pH was adjusted to around 7 or less, prior to chitosan addition for S. costatum and Chlorella sp., the concentration of chitosan required to obtain a 95–100% flocculation efficiency was reduced to 20 mg liter⁻¹ for Chlorella and 2 mg liter⁻¹ for S. costatum. The results are discussed in the light of the currently accepted theories on flocculation.     

重组卡介苗感染树突细胞的研究

在体内外试验中 ,树突细胞 (DC)均能摄取表达大肠杆菌麦芽糖结合蛋白 (MalE)的重组卡介苗 (rBCG·MalE)。应用流式细胞术测得荧光标记的rBCG·MalE在体内感染DC的水平在 1 % 2 % ,与感染巨噬细胞 (MΦ)的水平相当。体外抗原提呈试验结果显示 ,DC和MΦ能吞噬、加工rBCG·MalE并向T细胞杂交瘤FBU·B1 1提呈MalE蛋白抗原表位 ,而在体内试验中 ,从rBCG·MalE免疫小鼠脾脏中纯化的DC ,可检测到MalE表位MHCⅡ复合物 ,而纯化的MΦs却测不到。这表明DC在起始抗分枝杆菌的免疫保护中发挥关键作用。     

Sulfometuron incorporation in cationic micelles adsorbed on montmorillonite

The aim of this study was to understand the interactions between alkylammonium cations present as monomers and micelles and a clay mineral, montmorillonite, to develop slow release formulations of anionic herbicides, such as sulfometuron (SFM) whose leaching in soils is an environmental and economic problem. In the proposed formulation the herbicide is incorporated in positively charged micelles of quaternary amine cations, which in turn adsorb on the negatively charged clay. The adsorption of hexadecyltrimethylammonium (HDTMA) and octadecyltrimethylammonium (ODTMA) on montmorillonite was studied above and below their critical micelle concentrations (CMC). At concentrations above the CMC, the loading exceeded the clay's cation exchange capacity (CEC) and indicated higher affinity of the cation with the longer alkyl chain. An adsorption model could adequately simulate adsorption at concentrations below the CMC, and yield fair predictions for the effect of ionic strength. The model indicated that above the CMC adsorbed micelles contributed significantly to the amount of ODTMA adsorbed. Evidence for adsorption of ODTMA micelles on montmorillonite was provided by X-ray diffraction, freeze-fracture electron microscopy, and dialysis bag measurements. SFM was not adsorbed directly on the clay mineral, and adsorbed at low levels, when the organic cation was adsorbed as monomers. In contrast, a large fraction of SFM adsorbed on the clay mineral when incorporated in micelles that adsorbed on the clay.     

Traceability of ammonia-oxidizing bacteria in compost-treated soils

Composts are increasingly used as environmentally safe biofertilizers in sustainable agriculture all over the world. Although it is well known that composts may contribute to soil vitality and sustainability, and in the enhancement of various soil microbiological processes, little is known about their direct or indirect effects on a microbial-community or population level. Ammonia oxidation by autotrophic ammonia-oxidizing bacteria (AOB) is a key process in agricultural and natural ecosystems and plays an important role in the global nitrogen cycle. Here, we studied the diversity and community composition of ammonia oxidizers in a long-term crop rotation field experiment (>10 years) where four major types of compost (from organic waste, cattle manure, green waste and sewage sludge) had been applied annually. The methods used ranged from PCR-DGGE (denaturing gradient gel electrophoresis) and cloning of 16S rDNA fragments to quantitative real-time PCR. Cluster analysis of DGGE profiles differentiated between the microbial communities of composts, compost-treated soils and mineral-fertilized soils. The community composition of the composts was not reflected in the community composition of the compost-treated soils. Sequencing of screened clones revealed a characteristic AOB community structure for the representative soil sample and the four composts. All AOB-like sequences grouped within the Nitrosospira cluster 3 and 4 and within the Nitrosomonas cluster 6 and 7. The average AOB abundance in compost-treated soils was two times higher than in mineral-fertilized soils (4.3×10⁷ and 1.9×10⁷, respectively). Our data suggest that composts do not leave direct microbial imprints in soils after long-term amendment, but an indirect effect on the AOB community was evident.     

Structural and functional diversity of soil microbes is affected by elevated [CO<Subscript>2</Subscript>] and N addition in a poplar plantation

Background, Aims, and Scope  The genetic structure and the functionality of soil microbes are both important when studying the role of soil in the C cycle in elevated CO₂ scenarios. The aim of this work was to investigate the genetic composition of the fungal community by means of PCR-DGGE and the functional diversity of soil micro-organisms in general with MicroResp-based community level physiological profiling (CLPP) in a poplar plantation (POPFACE) grown under elevated [CO₂] with and without nitrogen fertilization. Materials and Methods  The POPFACE experimental plantation and FACE facility are located in central Italy, Tuscania (VT). Clones of Populus alba, Populus nigra and Populus x euramericana were grown, from 1999 to 2004, in six 314 m² plots treated either with atmospheric (control) or enriched (550 μmol mol⁻¹) CO₂ with FACE (Free Air CO₂ Enrichment) technology in each growing season. Each plot is divided into six triangular sectors, with two sectors per poplar genotype: three species × two nitrogen levels. After removal of the litter layer one soil core per genotype (10 cm wide, 20 cm depth) was taken inside each of the three sectors in each plot, for a total of 36 soil cores (3 replicates × 2 [CO₂] × 2 fertilization × 3 species) in October 2004 and in July 2005. DNA was extracted with a bead beating procedure. 18S rDNA gene fragments were amplified with PCR using fungal primers (FR1 GC and FF390). Analysis of CLPP was performed using the MicroResp method. Carbon substrates were selected depending on their ecological relevance to soil and their solubility in water. In particular rhizospheric C sources (carboxylic acids and carbohydrates) were chosen considering the importance of root inputs for microbial metabolism. Results  The fertilization treatment differentiated the fungal community composition regardless of elevated [CO₂] or the poplar species; moreover the number of fungal species was lower in fertilized soil. The effect of elevated [CO₂] on the fungal community composition was evident only as interaction with the fertilization treatment as, in N-sufficient soils, the elevated [CO₂] selected a different microbial community. For CLPP, the differ ent poplar species were the main factors of variation. The FACE treatment, on average, resulted in lower C utilization rates in un-fertilized soils and higher in fertilized soils. Discussion  Fungal biomass and fungal composition depend on different factors: from previous studies we know that the greater quantity and the higher C/N ratio of organic inputs under elevated [CO₂] influenced positively the fungal biomass both in fertilized and in un-fertilized soil, whereas nitrogen availability resulted to be the main determinant of fungal community composition in this work. Whole active microbial community was directly influenced by the soil nutrient availability and the poplar species. Under elevated CO₂ the competition for N with plants strongly affected the microbial communities, which were not able to benefit from added rhizospheric substrates. Under Nsufficient conditions, the increase of microbial activity due to [CO₂] enrichment was related to a more active microbial community, favoured by the current availability of C and N. Conclusions  Different factors influenced the microbial community at different levels: poplar species and root exudates affected the functional properties of the microbial community, while the fungal specific composition (as seen with DGGE) remained unaffected. On the other hand, factors such as N and C availability had a strong impact on the community functionality and composition. Fungal community structure reflected the availability of N in soils and the effect of elevated [CO₂] on community structure and function was evident only in N-sufficient soils. The simultaneous availability of C and N was therefore the main driving force for microbial structure and function in this plantation. Recommendations and Perspectives  Using the soil instead of soil extracts for CLPP determination provides a direct measurement of substrate catabolism by microbial communities and reflects activity rather than growth because more immediate responses to substrates are measured. Further applications of this approach could include selective inhibition of different microbial functional groups to investigate specific CLPPs. To combine the structural analysis and the catabolic responses of specific microbial communities (i.e. fungi or bacteria) could provide new outlooks on the role of microbes on SOM decomposition. ESS-Submission Editor: Dr. Kirk Semple (k.semple@lancaster.ac.uk)