GABAA Receptors in the Mongolian Gerbil: a PET Study Using [18F]Flumazenil to Determine Receptor Binding in Young and Old Animals.

PURPOSE: Plastic changes in the central auditory system involving the GABAergic system accompany age-related hearing loss. Such processes can be investigated with positron emission tomography (PET) imaging using [18F]flumazenil ([18F]FMZ). Here, [18F]FMZ PET-based modeling approaches allow a simple and reliable quantification of GABAA receptor binding capacity revealing regional differences and age-related changes. PROCEDURES: Sixty-minute list-mode PET acquisitions were performed in 9 young (range 5-6 months) and 11 old (range 39-42 months) gerbils, starting simultaneously with the injection of [18F]FMZ via femoral vein. Non-displaceable binding potentials (BPnd) with pons as reference region were calculated for auditory cortex (AC), inferior colliculus (IC), medial geniculate body (MGB), somatosensory cortex (SC), and cerebellum (CB) using (i) a two-tissue compartment model (2TCM), (ii) the Logan plot with image-derived blood-input (Logan (BI)), (iii) a simplified reference tissue model (SRTM), and (iv) the Logan reference model (Logan (RT)). Statistical parametric mapping analysis (SPM) comparing young and old gerbils was performed using 3D parametric images for BPnd based on SRTM. Results were verified with in vitro autoradiography from five additional young gerbils. Model assessment included the Akaike information criterion (AIC). Hearing was evaluated using auditory brainstem responses. RESULTS: BPnd differed significantly between models (p < 0.0005), showing the smallest mean difference between 2TCM as reference and SRTM as simplified procedure. SRTM revealed the lowest AIC values. Both volume of distribution (r2 = 0.8793, p = 0.018) and BPnd (r2 = 0.8216, p = 0.034) correlated with in vitro autoradiography data. A significant age-related decrease of receptor binding was observed in auditory (AC, IC, MGB) and other brain regions (SC and CB) (p < 0.0001, unpaired t test) being confirmed by SPM using pons as reference (p < 0.0001, uncorrected). CONCLUSION: Imaging of GABAA receptor binding capacity in gerbils using [18F]FMZ PET revealed SRTM as a simple and robust quantification method of GABAA receptors. Comparison of BPnd in young and old gerbils demonstrated an age-related decrease of GABAA receptor binding.

Pectoralis major muscle of turkey displays divergent function as correlated with meat quality.

Fresh turkey meat color is determined by many factors that include muscle fiber type composition and heme protein concentrations. These factors either are affected by or influence biochemical events occurring postmortem. Deviations in the processing environment also can result in aberrant fresh meat quality and may ultimately change the quality characteristics of further processed products. Our objective was to describe the underlying cause and significance of the two-toning color defect in fresh turkey breast. In the first experiment, pectoralis major muscles were collected, classified as single- or two-toned, and analyzed using image processing to characterize fresh turkey color. Samples from the large and small lobes of the pectoralis major muscle were collected for pH, glycolytic intermediates, protein abundance, mRNA expression, and quality characteristics. In the second experiment, time from stun to exsanguination was tested as a promoter of fresh turkey color. Results from the first experiment showed that the turkey breast possesses two distinct lobes. The large lobe had greater (P < 0.05) glycolytic potential, lactate content, lactate dehydrogenase (LDH) abundance, and centrifugal drip loss, while pH, myoglobin mRNA expression, and soluble protein levels were lower (P < 0.05) compared to the small lobe. Results from the second experiment showed that reducing time from stun to exsanguination enhanced (P < 0.05) fresh turkey color by mitigating the differences between the two lobes. Our results also showed that birds exsanguinated first had greater (P < 0.05) muscle pH values and body temperatures. These results show inherent differences in breast muscle and processing conditions interact to establish variations in fresh turkey color.

New packaging technologies for the 21st century.

This paper reviews the major influencers that will drive change in meat packaging. A review of the current state of fresh-meat packaging in the US has shown a continued evolution to case ready packaging, with 60% of the packages audited being in the case ready format, versus 49% just two years earlier. Additionally, the market is moving to a higher degree of convenience in the meat case, and reducing the linear feet devoted to fresh meat (69% fresh meat linear feet two years ago, versus 63% in 2004). Additional evidence for the growth of convenience items was shown by a 48% growth in shelf stable meal kits between 1998 and 2003. Packaging innovations have been developed to meet these needs for convenience, but have largely been implemented outside of the meat industry. These include, but are not limited to, lines of hand-held soups, self-heating cans and cartons that are replacing the traditional steel can for retort purposes. The recent developments of films that are ovenable in traditional as well as microwave ovens are critical to the further advancement of convenience meat items. Material costs are also driving the need for packaging innovations. Polyethylene costs rose 20% during the second half of 2003, which is largely due to increased petroleum costs. As petroleum costs are sustained at the current high levels, renewable packaging for food, such as materials based on polylactide, will become more feasible. Labor costs and availability at retail will continue to drive the demand for case ready packaging innovations. The recent regulatory approval of carbon monoxide in fresh meat packaging in the US will enable greater usage of low oxygen packaging formats and should provide greater retail acceptance of case ready in the US.

Pork characteristics as affected by two populations of swine and six crude protein levels.

Previous research has investigated the effect of genetic line and dietary CP on gilt growth and carcass composition. The aim of this research was to characterize lean tissue composition, color, tenderness, and water-holding capacity as affected by protein level and genetic lines. Thirty-six Gene Pool pigs, a population with low lean growth potential, and 36 Hampshire pigs, a population with a high lean growth potential, had ad libitum access to diets consisting of 10, 13, 16, 19, 22, or 25% CP. Longissimus muscles of Hampshire pigs were lighter, more red, and more yellow than those from Gene Pool pigs (P< .01). Redness and yellowness of longissimus muscles decreased linearly (P < .01) as protein level increased. Chops from Hampshire pigs required less force and less total energy to shear but had lower cooking yields and water-holding capacity than chops from Gene Pool pigs (P < .01). Chops from pigs fed 19 and 22% protein required greater force (quadratic, P < .01) and more total energy (quadratic, P < .05) to shear. Objective color differences revealed that restructured, cured hams from Hampshire pigs were lighter, less red, and had less intense cured color (P < .01). The Hampshire line of gilts produced pork muscle that was leaner, more pale in color, more tender, and lower in water-holding capacity than the Gene Pool line. Level of dietary CP caused alterations in tenderness and lean composition, especially when diets contained less protein.