Which anatomical region determines a positive flexion test of the distal aspect of a forelimb in a nonlame horse?

Reasons for performing study: The flexion test is used routinely as part of lameness and prepurchase examinations. However, little is known about the mechanisms that cause a positive response to a flexion test. Objective: To determine which anatomical regions play a role in a positive outcome of a flexion test of the distal aspect of a forelimb in a nonlame horse. Methods: Eight clinically sound Dutch Warmblood horses were subjected to a standardised flexion test (force 250 N, time 60 s) inducing a consistent lameness. To discriminate between different areas of the distal aspect of a forelimb, effects of various nerve blocks on the outcome of the flexion test were investigated. Low palmar digital, palmar at the abaxial aspects of the base of the proximal sesamoids, high palmar, ulnar and low 4‐point nerve blocks were performed. Flexion test induced lameness was scored before and after each nerve block in separate sessions. Results: The low palmar digital nerve blocks and nerve blocks of the palmar nerves at the abaxial aspect of the base of the proximal sesamoid bones had no significant effect on the flexion test induced lameness score. The ulnar, high palmar and, most dramatically, the low 4‐point nerve blocks all caused a significant (P<0.05) reduction in the flexion test induced lameness score. Conclusions: Anatomical structures (soft tissue nor synovial structures) located distal to the metacarpophalangeal joint appear to contribute only minimally to the outcome of a positive flexion test of the distal aspect of a forelimb in a clinically nonlame horse. The structures in the region of, and including, the metacarpophalangeal joint appear to contribute most to a positive flexion test of the distal aspect of a forelimb in a nonlame horse. Potential relevance: The flexion test of the distal aspect of a forelimb may be sensitive for investigating the metacarpophalangeal joint region in horses free from lameness, but may be less relevant for structures distal to this region.     

Analytical pyrolysis of a soil profile under Scots pine

The chemical properties of pine needle litter cause slow decomposition, which results in an accumulation of highly lignocellulosic material on the forest floor. Decomposition of organic matter is important for the nutrient turnover in pine forests on nutrient-poor soils. We studied the biodegradation of needles in an organic layer focusing on the various stages of lignin degradation by fungi. Samples were obtained from pine needle litter and a stratified organic layer over nutrient-poor sand under a 60-year-old Scots pine (Pinus sylvestris forest stand. Pyrolysis mass spectrometry (PyMS) and pyrolysis gas chromatography mass spectrometry (PyGCMS) were used to characterize the chemical composition of the needles and the soil. The pyrolysis data show that diterpenoid acids are a main component in fresh needles, but rapidly decrease in the organic layer of the soil, as a result of decomposition. The chemical composition of the soil profile is dominated by guaiacyl lignin and polysaccharides from needle litter. The hexose/pentose ratio increases with depth in the soil profile. The partial preservation of hexose polymers is the result of the preferential decomposition of pentose polymers by white-rot fungi, and points to the input of microbially synthesized polysaccharides. Indications for the degradation of guaiacyl lignin are also found in the soil profile. Oxidative reactions by soil fungi result in a shortening of the side chain of the guaiacyl lignin derivatives and an increase of carbonyl and carboxyl groups. These degradational patterns of lignin in the soil profile under Scots pine are similar to those observed in lignin model compounds and wood lignin degraded by fungi under controlled laboratory conditions.     

A dietary effect on some cellular and humoral blood parameters of rainbow trout, Oncorhynchus mykiss (Walbaum)

Abstract. Young rainbow trout, Oncorhynchus mykiss (Walbaum), with a mean weight of 100g were used in a 42-day study designed to investigate the influence on several haematological characteristics of two different diets containing 32·5% and 47% protein and 41·4% and 20·0% carbohydrate, respectively. The observed overall mean values of the different blood parameters were similar to those reported in literature. Leucocrit, percentage of periodic-amino-Schiff positive granulocytes, percentage of mature lymphocytes and the percentage of the fourth plasma protein fraction were significantly affected by the diet.     

Mortality of marine cultured rainbow trout, Oncorhynchus my kiss (Walbaum), during the summer in the Netherlands

Abstract. In northern Europe, rearing of rainbow trout, Oncorhynchus mykiss (Walbaum), in sea cages is a substantial part of fish culture. One of the major constraints for the development of this system in other parts of Europe is the unexplained mortality of fish during the summer. To investigate environmental aspects of this mortality, rainbow trout, cultured in cages in sea water, were monitored from May to October for three successive years. No evidence of bacterial involvement could be found, while water temperature and salinity strongly influence the mortality. This supports the suggestion that the mortality has been caused by patho-physiological changes due to higher metabolic requirements for osmoregulation at elevated water temperature in the saline environment which might result in a dissipation of O₂ by CO₂ on the hemoglobin.