The relationship between postmortem urinary catecholamines, meat ultimate pH, and shear force in bulls and cows

We investigated the relationship between stress responsiveness and meat quality in cattle. The cattle were 16-19-month-old Mixed (n=37, 303 kg) or Non-mixed (n=23, 279 kg) Friesian bulls and Friesian cull cows (1.5-7 years) that were classified Unfinished (n=133, 195 kg) or Finished for 3 months (n=34, 252 kg). A portion of m. longissimus lumborum (LL) muscle was obtained from consecutive animals for a single days slaughter of 227 cattle processed through a hot boning plant. Catecholamines were obtained from bladder urine. Ultimate pH, lactate, glycogen, glycolytic potential and representative sarcomere lengths were determined from 20-h muscle samples. Shear force measurements were from meat aged at 15 °C for 20 and 90 h. Urinary noradrenaline was similar between Mixed (14.86 ng/μmol creatinine) and Non-mixed bulls (14.07 ng/μmol creatinine) and Finished cows (15.24 ng/μmol creatinine) and elevated in the Unfinished cows (22.28 ng/μmol creatinine). Urinary adrenaline was higher in Mixed bulls (9.5 ng/μmol creatinine) than Non-mixed bulls (5.7 ng/μmol creatinine) and higher in both Unfinished cows (16.67 ng/μmol creatinine) and Finished cows (14.19 ng/μmol creatinine). For bulls that are growing well on-farm, with a only short period of fasting prior to slaughter, pH(u) is a good predictor of meat tenderness. In this situation, stressors that lower muscle glycogen pre-slaughter can have a significant effect on meat shear force, and individual animals with elevated urinary adrenaline were the most susceptible. However, in the case of cows, adrenaline responses are not necessarily associated with glycogen depletion and pH(u) is less affected than for bulls. Furthermore, the ability of meat to tenderise fully, related to reduced proteolytic turnover, is reduced in nutritionally compromised animals such as the Unfinished cows.     

Cover Image,Volume 97, Issue 11

The cover image, by Hannah C Wells et al., is based on the Research Article Deer leather: analysis of the microstructure affecting pebble, DOI: 10.1002/jsfa.8199 .

     

Green fluorescent protein as a reporter to monitor gene expression and food colonization by Aspergillus flavus

Transformants of Aspergillus flavus containing the Aequorea victoria gfp gene fused to a viral promoter or the promoter region and 483 bp of the coding region of A. flavus aflR expressed green fluorescence detectable without a microscope or filters. Expression of green fluorescent protein fluorescence was correlated with resistance to aflatoxin accumulation in five corn genotypes inoculated with these transformants.     

Effects of temperature and volatile anesthetics on GABA(A) receptors

BACKGROUND: Potentiation of the activity of the gamma-aminobutyric acid type A (GABA(A)) receptor channel by volatile anesthetic agents is usually studied in vitro at room temperature. Systematic variation of temperature can be used to assess the relevance of this receptor to general anesthesia and to characterize the modulation of its behavior by volatile agents at normal body temperature. METHODS: Potentiation of the GABA(A) receptor by halothane, sevoflurane, isoflurane, and methoxyflurane was studied at six temperatures in the range 10-37 degrees C using the whole-cell patch-clamp technique and mouse fibroblast cells stably transfected with defined GABA(A) receptor subunits. RESULTS: Control GABA concentration-response plots showed small and physically reasonable changes in the GABA concentration required for a half-maximal effect, the Hill coefficient, and maximal response over the range 10-30 degrees C. Potentiations of GABA (1 microM) responses by aqueous minimum alveolar concentrations of the volatile anesthetic agents decreased with increasing temperature from 10-37 degrees C in an agent-specific manner (methoxyflurane > isoflurane > sevoflurane > halothane) but tended to equalize at normal body temperature (37 degrees C). These findings are in line with published results on the temperature dependence of anesthetic potencies in animals. CONCLUSIONS: These results are consistent with direct binding of volatile anesthetic agents to the GABA(A) receptor channel playing an important role in general anesthesia. The finding that the degree of anesthetic potentiation was agent-specific at low temperatures but not at 37 degrees C emphasizes the importance of doing in vitro experiments at normal body temperature.     

The material basis for reduced mechanical properties in oim mice bones

Osteogenesis imperfecta (OI), a heritable disease caused by molecular defects in type I collagen, is characterized by skeletal deformities and brittle bones. The heterozygous and homozygous oim mice (oim/+ and oim/oim) exhibit mild and severe OI phenotypes, respectively, serving as controlled animal models of this disease. In the current study, bone geometry, mechanics, and material properties of 1-year-old mice were evaluated to determine factors that influence the severity of phenotype in OI. The oim/oim mice exhibited significantly smaller body size, femur length, and moment of area compared with oim/+ and wild-type (+/+) controls. The oim/oim femur mechanical properties of failure torque and stiffness were 40% and 30%, respectively, of the +/+ values, and 53% and 36% of the oim/+ values. Collagen content was reduced by 20% in the oim/oim compared with +/+ bone and tended to be intermediate to these values for the oim/+. Mineral content was not significantly different between the oim/oim and +/+ bones. However, the oim/oim ash content was significantly reduced compared with that of the oim/+. Mineral carbonate content was reduced by 23% in the oim/oim bone compared with controls. Mineral crystallinity was reduced in the oim/oim and oim/+ bone compared with controls. Overall, for the majority of parameters examined (geometrical, mechanical, and material), the oim/+ values were intermediate to those of the oim/oim and +/+, a finding that parallels the phenotypes of the mice. This provides evidence that specific material properties, such as mineral crystallinity and collagen content, are indicative and possibly predictive of bone fragility in this mouse model, and by analogy in human OI.     

Book Review

Abstract

“Pharmaceutical Process Validation” Edited by Bernard T. Loftus and Robert A. Nash Published by Marcel Dekker, Inc., New York, NY, 1984.     

Measuring effects of a skills training intervention for drug abusers.

Examined the effectiveness of a supplemental skills training and social-network-development aftercare program with 130 drug abusers (aged 15–55 yrs) from 4 residential therapeutic communities. The program included training in assertiveness, problem-solving, stress management, and giving and receiving praise; training techniques included group discussion, modeling, role playing and feedback. Pre- and posttesting with a problem situation inventory showed that the intervention produced positive effects on Ss' performance at the conclusion of treatment. Performance improved in situations involving avoidance of drug use, coping with drug relapse, social interaction, interpersonal problem solving, and coping with stress. It is concluded that as a reentry strategy, the supplemental intervention is an effective adjunct to residential treatment. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)