Downregulation of organic anion transporters OAT1 and OAT3 correlates with impaired secretion of para-aminohippurate after ischemic acute renal failure in rats.

Ischemic acute renal failure (iARF) was described to reduce renal extraction of the organic anion para-aminohippurate (PAH) in humans. The rate-limiting step of renal organic anion secretion is its basolateral uptake into proximal tubular cells. This process is mediated by the organic anion transporters OAT1 and OAT3, which both have a broad spectrum of substrates including a variety of pharmaceutics and toxins. Using a rat model of iARF, we investigated whether impairing the secretion of the organic anion PAH might be associated with downregulation of OAT1 or OAT3. Inulin and PAH clearance was determined starting from 6 up to 336 h after ischemia-reperfusion (I/R) injury. Net secretion of PAH was calculated and OAT1 as well as OAT3 expression was analyzed by RT-PCR and Western blotting. Inulin and PAH clearance along with PAH net secretion were initially diminished after I/R injury with a gradual recovery during follow-up. This initial impairment after iARF was accompanied by decreased mRNA and protein levels of OAT1 and OAT3 in clamped animals compared with sham-operated controls. In correlation to the improvement of kidney function, both mRNA and protein levels of OAT1 and OAT3 were upregulated during the follow-up. Thus decreased expression of OAT1 and OAT3 is sufficient to explain the decline of PAH secretion after iARF. As a result, this may have substantial impact on excretion kinetics and half-life of organic anions. As a consequence, the biological effects of a variety of organic anions may be affected after iARF.

Interrelationships between descriptive texture profile sensory panel and descriptive attribute sensory panel evaluations of beef Longissimus and Semitendinosus muscles.

The objectives of our study were to examine the relationships between highly trained and experienced descriptive texture profile (DTP) sensory panel and trained descriptive attribute (DA) sensory panel evaluations, and to evaluate the effects of muscle fiber orientation on sensory panel tenderness scores of beef longissimus lumborum (LL) and semitendinosus (ST) muscles. Eighteen LL and 18 ST muscles were cut into 2.54 cm steaks and cooked to 71°C; then 1.27×1.27×2.54-cm cubes were removed using two methods (parallel with the muscle fiber orientation and perpendicular to the steak cut surface) and presented to the two sensory panels. Both panels detected differences among replications (muscles from different carcasses); however, a panelist × replication effect occurred for the DA sensory panel. Both panels detected differences (p<0.05) in LL muscle fiber orientation for most attributes related to tenderness; however, few differences were detected for flavor and juiciness traits for either muscle. Numerous significant (r ⩾ 0.50 or ⩽ -0.50) correlations occurred between DTP and DA panel attributes and were generally higher when cubes were cut perpendicular to the steak cut surface. The DTP panelists were more consistent in their evaluations of texture attributes; however, they were more sensitive to muscle fiber orientation. Both panels were effective in detecting differences among replications.

Interrelationships among evaluations of beef longissimus and semitendinosus muscle tenderness by Warner-Bratzler shear force, a descriptive-texture profile sensory panel, and a descriptive attribute sensory panel.

The objective of our study was to examine the interrelationships among Warner-Bratzler shear force (WBSF) determinations, evaluation by a highly trained descriptive-texture-profile (DTP) sensory panel, and evaluation by a trained descriptive attribute (DA) sensory panel as affected by muscle fiber orientation of samples and shear-blade type. Longissimus lumborum and semitendinosus muscles (n = 18 of each) were cut into 2.54-cm steaks, which were cooked to 71 degrees C. Cores were obtained with two methods (parallel to the muscle fiber orientation and perpendicular to the cut steak surface), used for WBSF determinations with the typical V-shaped blade and modified WBSF determinations with a flat blade, and presented to the DTP and DA sensory panels. The V-shaped blade resulted in 1.4 to 2.5 kg lower (P < .05) mean WBSF values than the flat blade for both muscles. Cores taken parallel to the longissimus muscle fiber orientation had .64 kg higher (P < .05) mean WBSF values than cores taken perpendicular to the cut steak surface. Both panels detected differences among carcass replications; however, a panelist x replication effect (P < .05) occurred for the DA panel. Both panels detected differences (P < .05) in muscle fiber orientation for attributes related to tenderness. Correlations between sensory panel scores and WBSF values were dependent on blade type and coring method. Blade type and coring method had greater effects on correlations between sensory scores and WBSF values for the DTP panel than for the DA panel. Correlations between scores by both sensory panels and WBSF values were comparable. The more highly trained DTP panelists were more consistent in their evaluations of texture attributes; however, they were more sensitive to muscle fiber orientation. Both panels were effective in detecting differences among carcass replications.

Refrigerated shelf life of vacuum-packaged, previously frozen ostrich meat.

Previously frozen ostrich meat was evaluated over 28 days to determine the refrigerated shelf life. Intact steaks and ground meat from three ostrich carcasses were vacuum-packaged, frozen to -40°C for 5 days, and stored in a 0°C walk-in cooler. Instrumental analysis of CIE L*a*b* values indicated that ostrich meat was very dark in color, initially and over time. Microbial growth stayed slightly below 1.0 × 10(7) CFU/g for up to 21 days of refrigerated storage. Sensorially evaluated color showed an increase (p <0.05) in darkness over time. Percentage of browning increased (p<0.05) over time from 1% initially to 55% for intact steaks and 75% for ground meat by 28 days. Sensory aroma scores significantly (p<0.05) changed over time, with unacceptable aroma occurring by 14 days. Previously frozen, vacuum-packaged ostrich meat stored under refrigerated conditions should be used within 10 days.