Chemical transformations in individual ultrasmall biomimetic containers

Individual phospholipid vesicles, 1 to 5 micrometers in diameter, containing a single reagent or a complete reaction system, were immobilized with an infrared laser optical trap or by adhesion to modified borosilicate glass surfaces. Chemical transformations were initiated either by electroporation or by electrofusion, in each case through application of a short (10-microsecond), intense (20 to 50 kilovolts per centimeter) electric pulse delivered across ultramicroelectrodes. Product formation was monitored by far-field laser fluorescence microscopy. The ultrasmall characteristic of this reaction volume led to rapid diffusional mixing that permits the study of fast chemical kinetics. This technique is also well suited for the study of reaction dynamics of biological molecules within lipid-enclosed nanoenvironments that mimic cell membranes.     

Seasonal changes in pasture populations of infective larvae of gastrointestinal nematodes of cattle in eastern Nigeria

The seasonal changes in the populations of trichostrongylid infective larvae (L3) on herbage and in soil samples collected from pastures grazed by beef cattle were studied at Nsukka, eastern Nigeria, from April 1980 to July 1981. Large numbers of L3 were recovered from all samples collected during the rainy season (April to October). The rainy season herbage infestation was characterised by three clearly defined peaks. The first, which followed an 'early rains' (April) rise, occurred in the second half of May while the larger second and third peaks occurred in late July and October respectively. It is suggested that each of these peaks represented a distinct wave of infestation by a separate generation consisting of the three trichostrongylids concerned, namely Cooperia, Haemonchus and Trichostrongylus species. Although there was a sharp fall in pasture infestation following the onset of the dry season, appreciable numbers of L3 were still present on herbage in early December. The implications of these findings have been discussed in relation to the choice of effective strategic anthelmintic programmes for the prophylaxis and control of bovine parasitic gastroenteritis in the Nsukka area.     

Relationships involving several types of extractives of five native argentine wood species of genera Prosopis and Acacia

The relationships existing among the values obtained when extracting the wood of four Argentinean species of Prosopis (P. alba, P. kuntzei, P. nigra, and P. ruscifolia) and one of the Acacia (A. aroma) by several procedures were evaluated and discussed. The used methods were: extraction in toluene/ethanol and hot water; determination of tannic and non-tannic content; measurement of phenolic compounds. Additionally, liquid chromatography (HPLC) was also used in order to quantitatively evaluate the content of (−)-mesquitol, a relatively unusual flavonoid (flavanol type). The total amount of Oxidation Products was also measured. They result from oxidation and polymerization processes of phenolic compounds occurring during heartwood formation, and were not separated during chromatographic analysis. Data evidenced a linear trend (R² = 0.970) between organic and tannic extractives of all species, and a similar one (R² = 0.927) between total phenols and tannic (or organic) extractives in the case of heartwood of Prosopis species. Interestingly, for sapwood very different values of organic extracts, tannic content or Oxidation Products type compounds were measured in spite of a similar amount of phenolic substances. Moreover, the various species presented the same peaks in chromatograms, thus evidencing the chemical similarity of compounds but a different quantity between heartwood and sapwood and also among the various species. The observed similarity implied that the various methods of extraction did not really extract only a single class of substances, and that great care must be adopted when using some specific procedures for extractions.Furthermore, the existing relationships between extractives and selected technological properties, namely specific volumetric shrinkage coefficient (BSvol) and natural durability (evaluated in terms of mass loss after fungal attacks in laboratory conditions), were given. It appeared that in heartwood BSvol was well correlated to organic extractives (R² = 0.984), thus evidencing the microimpregnation of cell walls by extractives, but the fitting quality of the correlation was dependent on the type of extractives used. Analogously, a good relationship between mass loss and phenolic compounds existed (R² = 0.764), and in this case the value of R² was even more dependent on the considered extracts. Moreover, the availability of quantitative data on several Prosopis species allowed to consistently evaluate the bioactivity of (−)-mesquitol on the resistance against fungal attack, and the logarithmic form of the relationship between mass loss and (−)-mesquitol content suggested a direct fungicidal activity of this compound. On the other hand, data also evidenced that neither phenolic compounds nor (−)-mesquitol can be considered as the unique and definite factor able to determine the durability of the considered species.     

Carbon Isotope Discrimination and Productivity in Field-Grown Barley Genotypes

Five barley genotypes of different origins were used to examine the relationships between carbon isotope discrimination (Δ) and grain yield, yield components, dry aerial biomass and harvest index under rainfed and irrigated Mediterranean conditions. High positive correlations were found between Δ and grain yield and harvest index under both water conditions, suggesting that Δ may represent efficiency of dry matter partitioning to the grain. This hypothesis was also supported by the positive correlation found between Δ and thousand-grain weight when all the data were considered. The two drought-tolerant genotypes LM2887 and Tadmor presented the smallest difference between the two treatments for traits related to productivity as well as the highest Δ values. These results highlight the potential of Δ as a selection criterion in barley breeding in Mediterranean regions. They also encourage the study of the genetics of Δ and the identification of molecular markers linked to its variation in available progenies derived from crosses between the genotypes used in the present paper.     

The influence of supplemental alpha-galactosidase and phytase in a vegetable ration for dogs on the digestibility of organic components and phytate phosphorus

The use of dry feeds for dogs is increasing for different reasons: in comparison to wet canned feed it is easier to handle, the amount to be given is smaller and the daily cost is less. In producing a dry pellet more vegetable ingredients are used that can contain several antinutritional factors. Some of them can be eliminated by heating. Others like galactosides and phytates are heat-resistant but can be broken down by adding the appropriate enzymes. The specific enzymes are indeed not secreted by the animal itself. In farm animals, e.g. pigs, alpha-galactosidase has been introduced in order to enhance the energetic value of these alphagalactosides (Veldman et al. 1993). In companion animals this enzyme is more often indicated as an antiflatulence agent, because the main alpha-galactosides present in legume seeds (stachyose, raffinose) are known as flatulence components (Fleming 1981). These oligosaccharides do not necessarily imply an overall lower nutrient digestibility. Zuo et al. (1996) did not prove a significant difference in digestibility between conventional and low oligosaccharide soybean meal in dog rations. Others however, (Wiernusz et al. 1995) reported the highest digestibilities and the best stool quality of those rations that contained the least amount of soybean oligosaccharides. On the other hand, phytates (phospho-inositols) are known as complexing agents of several divalent cations (Fe, Mg, Zn, Ca) and are themselves considered as a phosphorus source, unavailable to monogastric animals. Phytase is the appropriate enzyme, which is not secreted by the animal itself, but, when added to the diet, can enhance the bio-availability of several minerals and trace elements (Rimbach et al. 1994) by hydrolysing the phospho-inositol molecule. The aim of the experiment, reported here, is to investigate the influence of the addition of alpha-galactosidase, phytase, or both to a nearly complete vegetable ration, consisting of a relatively high content of galactosides and phytates. The combination of both enzymes was carried out because Wenk et al. (1993) reported a possible interaction between a carbohydrase and a phytase enzyme in pigs.     

Curriculum development in the Netherlands: introduction of tracks in the 2001 curriculum at Utrecht University, The Netherlands

The Faculty of Veterinary Medicine in Utrecht has recently introduced two major curriculum changes in order to keep pace with developments in research (the vast increase in scientific knowledge), in society (the quality awareness of veterinary clients), and in the veterinary profession, where a species and sector differentiation can be observed. After about 15 years during which the curriculum remained more or less unchanged, a radical curriculum revision was introduced in 1995. A further revision, with the introduction of separate study tracks, began in 2001. The 2001 curriculum focuses on academic and scientific training, active learning and problem solving, training in communication and professional behavior, and lifelong learning. It is divided into a four-year core curriculum, in which a broad, cross-species pathobiological insight is central, and a two-year track curriculum, through which students achieve a starting competence in a specific species or sector. The main teaching methods are tutorials and group tasks; practical work is used mainly to achieve specific veterinary skills. Teaching hours represent 30-35% of all study hours. Self-teaching is encouraged by providing study materials, self-teaching questions, teachers assigned to assist with self-teaching, and adequate facilities. The five tracks offered are Companion Animals/Equine; Food Animals; Veterinary Public Health; Veterinary Research; and Veterinary Administration and Management. All students follow a uniform 30-week clinical rotation program, while the track program is 42 weeks. A summary of admission procedures is given, as well as the times and procedures for track selection.     

Chronic obstructive mastitis in the camel. A clinicopathological study

Unilateral chronic mastitis in three she camels was due to obstruction of the teat canal by keratin. This lead to dilatation of the ducts, retention of milk and secondary bacterial infection. The teat canals and dilated ducts were lined by stratified squamous epithelium. There was excessive periductal fibrosis. Pasteurella hemolytica was isolated from one animal and Staphylococcus aureus from another. The fluid from the third animal was sterile. The condition was treated successfully by surgical amputation of the affected halves of the udder.