Denaturation of beta-lactoglobulin in pressure-treated skim milk

The kinetics of beta-lactoglobulin (beta-LG) denaturation in pressure-treated reconstituted skim milk samples over a wide pressurization range (100-600 MPa) and at various temperatures (10-40 degrees C) was studied. Denaturation was extremely dependent on the pressure and duration of treatment. At 100 MPa, no denaturation was observed regardless of the temperature or the holding time. At higher pressures, the level of denaturation increased with an increasing holding time at a constant pressure or with increasing pressure at a constant holding time. At 200 MPa, there was only a small effect of changing the temperature at pressurization. However, at higher pressures, increasing the temperature from 10 to 40 degrees C markedly increased the rate of denaturation. The two major genetic variants of beta-LG (A and B) behaved similarly to pressure treatment, although the B variant appeared to denature slightly faster than the A variant at low pressures (< or =400 MPa). The denaturation could be described as a second-order process for both beta-LG variants. There was a marked change in pressure dependence at about 300 MPa, which resulted in markedly different activation volumes in the two pressure ranges. Evaluation of the kinetic and thermodynamic parameters suggested that there may have been a transition from an aggregation-limited reaction to an unfolding-limited reaction as the pressure was increased.     

Factors associated with the effectiveness of antibiotic treatment for ovine virulent footrot

Factors associated with the proportion of sheep cured of virulent footrot after antibiotic treatment were studied in a field trial under dry environmental conditions. From 2 similar flocks, 1091 Merino sheep weighing about 50 kg and infected with virulent footrot received an intramuscular injection of either 12 mL of a mixture of penicillin (250 mg/mL) and streptomycin (250 mg/mL), 6 mL of long acting oxytetracycline (200 mg/mL) or 6 mL of a mixture of lincomycin (50 mg/mL) and spectinomycin (100 mg/mL). Variables that were significantly associated with the proportion of sheep cured were: the type of antibiotic used, the number of feet infected and the flock from which the sheep came. There was an interaction between antibiotic type and number of feet infected and between antibiotic type and flock in association with the proportion of sheep cured. The extent of paring and the occurrence of blowfly strike in footrot lesions treated with diazinon had no significant association with the proportion of sheep cured.     

Initial responses of woody vegetation, water quality, and soils to harvesting intensity in a Texas bottomland hardwood ecosystem

Sustainable management of bottomland hardwood forest ecosystems requires a knowledge of responses to management impacts, including timber harvesting. The effects of clearcutting and partial cutting on woody vegetation regeneration dynamics, surface and groundwater quality, soil physical properties, and soil respiration were tested in a bottomland hardwood ecosystem in southeastern Texas, USA, through comparison with non-cut control areas. Overstory removal only slightly affected composition of woody vegetation regeneration 1 year after harvesting compared with pre-harvest composition. Initial composition in both cutting treatments appeared to be the strongest determinant of post-harvest composition, at least for the first year after harvesting. There were few significant differences in groundwater properties when harvesting treatments were compared with control areas during a 17-month period following harvest. Turbidity, temperature, electrical conductivity, dissolved O₂, NH₄-N, NO₃-N, and PO₄-P of streamwater did not vary significantly among treatments. Slight decreases in total and macroporosity were observed in association with higher bulk densities at 0–5 cm depth in the clearcut and partial cut treatments. Saturated hydraulic conductivity values did not decline significantly with treatment intensity. No significant differences among treatments in measured soil physical properties were observed at 5–10 cm depth. Although in situ soil respiration increased with harvest intensity, treatment had no significant effect on mineral soil respiration. In summary, most variables showed only slight response to harvesting, thereby indicating that harvesting practices can be conducted with minimal initial impacts on measured response variables.     

Decision for surgery

Based on the clinical impression and the current knowledge of the clinical variables (rectal examination, abdominal distention, abdominal fluid, intractable pain) most likely to differentiate between medical and surgical cases, three decision trees are provided as a guide to making the management decision in a horse with abdominal pain. Prior elimination of horses with limited life expectancy because of age or function or where financial constraints are present is understood. It must be emphasized that most of the information presently available originates from referral centers where the prevalence of surgical candidates is much higher than in general practice. This would influence the accuracy of the clinician in identifying horses with a surgical lesion or estimating survival (positive predictive value).     

Incidence of major injuries, severe colic, and acute laminitis at American Horse Shows Association A- and B-rated shows

A questionnaire was designed to determine the incidence of major injuries, severe colic, and acute laminitis in horses at American Horse Shows Association (AHSA) A- and B-rated shows, ie, those shows requiring a veterinarian in attendance. The questionnaire was sent to the show stewards and filled out by the attending veterinarians of the AHSA A- and B-rated shows held from January 1982 to October 1984. Of 2,952 questionnaires sent out, 799 (27%) were completed and returned by veterinarians; 99 of them were discarded because of incomplete or misleading information. The study revealed a low incidence of major injuries, severe colic, and acute laminitis in horses at AHSA A- and B-rated shows. In 700 horse shows surveyed, there was a total of 231 major injuries, severe colic, or acute laminitis. Considering that the shows surveyed had a median number of 193 horses and a median duration of 3 days, the 231 injuries represent a relatively small number, compared with the general population at risk.     

Observations on the occurrence and inheritance in wheat of resistance to the grain aphid Sitobion avenae

Glasshouse screening tests with the aphid, Sitobion avenae, demonstrated resistance or extreme susceptibility in a minority of winter wheat cultivars. Assessments of some, but not all, resistant cultivars were apparently affected by the conditions of the test, and field observations confirmed some, but not all, of the glasshouse results. Rapier and Galahad were the most resistant of the cultivars currently available to British wheat growers. F₄ lines of spring wheat from crosses of wheat stocks resistant to S. avenae were screened by two methods and on average were resistant. Crosses differed in the amount of variability available for further selection, and wide-ranging segregation among the lines indicated that resistance genes differed among the parent stocks.