Matrix metalloproteinase- 9 may contribute to collagen structure modification during postmortem aging of beef

Matrix metalloproteinases (MMPs) are responsible for the turnover of intramuscular connective tissue in live animals. We hypothesize that MMPs may play a role in postmortem aging of beef muscles for the degradation of connective tissues. Four different experiments were performed to: 1) characterize MMP activity during postmortem aging of beef; 2) determine if the native beef MMP can contribute to connective tissue degradation in a simulated standard industry postmortem aging condition; 3) explore approaches to improve the native beef MMP activity and 4) characterize MMP activity in beef from cattle supplemented with supranutritional level of Zn. In experiment 1, MMP was active throughout the entire aging periods (3, 21, 42 and 63 d) for beef muscles Longissimus lumborum, Gluteus medius and Gastrocnemius, and the unknown MMP responsible for the collagen degradation was identified as MMP-9 by Western Blot. In experiment 2 and 3, MMP-9 activity was noticeable in the gels after 42 d of storage in the cooler. Moreover, the addition of ZnCl2 in the model system significantly increased MMP-9 activity when compared to the control (P < 0.01). In experiment 4, Longissimus thoracis from animals supplemented with a supranutritional Zn level had increased Zn availability and MMP-9 activity than those from animals fed with a control diet (P < 0.05). Further research is needed better understand MMP-9 mechanism during postmortem aging of meat. With a better understanding of MMP-9 in the aging process, the beef industry can provide better connective tissue management strategies for lower-quality beef cuts.

An investigation on the influence of various biochemical tenderness factors on eight different bovine muscles

This study's objective was to understand the relationships between biochemical tenderness components and subject/objective tenderness of eight muscles from beef carcasses. Longissimus thoracis (LT), pectoralis profundus (PP), supraspinatus (SS), triceps brachii (TB), gluteus medius (GM), rectus abdominus (RA), rectus femoris (RF), and semitendinosus (ST) were collected from 10 USDA upper 2/3 Choice beef carcasses and assigned to a two- or 21-day aging period (n=160). Troponin-T (TNT) degradation, desmin degradation, sarcomere length, collagen content, mature collagen crosslink density, intramuscular lipid content, pH, Warner-Bratzler Shear Force (WBSF) and trained sensory panel analyses were measured. A Pearson correlation analysis was conducted to determine the relationship between each tenderness contributor measured in this study with WBSF or the overall tenderness evaluated by the trained panelist for each of the eight muscles. In addition, multivariate regression models were constructed to confirm this relationship. The results showed that muscle anatomical locations and physiological functions driven by muscle fiber types may explain some of the biochemical/tenderness differences found in this study. The correlation analysis showed that each muscle had a specific tenderness factor(s) that contributed to the overall tenderness. For instance, tenderness for LT, TB, GM, RA, and ST may be influenced more by proteolytic degradation, while the collagen characteristics may primarily influence tenderness for PP. Also, lipid content has a significant influence on GM tenderness. Finally, the multivariate regression model showed that almost all of the biochemical measurements conducted in this study played a minor but important role as an overall tenderness predictor on a whole carcass basis. Increasing the knowledge base on the various tenderness components' level of contribution will allow end-users to develop specific tenderness management strategies to ensure consistent tenderness in beef products.

PSIII-1 A preliminary study to investigate the contribution of different tenderness factors to beef loin, tri-tip and heel tenderness

The objective of this study was to identify the relative contribution of tenderness factors for 3 beef muscles with similar tenderness ratings. Longissimus lumborum (loin), tensor fascia latae (tri-tip) and gastrocnemius (heel) were collected from 10 USDA choice beef carcasses, fabricated into steaks and assigned to a 5 or 21 d aging period (n=60). Heel had the greatest relative troponin-T degradation %, followed by tri-tip and loin (68.10, 53.42 and 35.01 % respectively; P&lt; 0.01). Tri-tip had the longest sarcomere, followed by heel and loin (3.01, 2.59 and 1.71 µm, respectively; P &lt; 0.01), and heel increased in sarcomere length from 5 to 21 d of postmortem storage (2.49 vs 2.70 µm; P&lt; 0.05). As expected, heel had the greatest collagen content, followed by tri-tip and loin (6.06, 3.98 and 2.76 mg/g of muscle tissue, respectively; P&lt; 0.01), and collagen content decreased for all cuts from 5 to 21 d of postmortem storage (4.64 vs 3.90 mg/g muscle tissue; P&lt; 0.05). Out of the 3 cuts, heel had the highest collagen crosslink density (0.20 mol/mol collagen; P&lt; 0.05), while loin and tri-tip did not differ (0.13 and 0.15 mol/mol collagen, respectively; P &gt;0.05). Collagen crosslink density increased for all cuts from 5 to 21 d of postmortem storage (0.14 vs 0.20; P&lt; 0.01). Heel had lower lipid content than the others (2.68 %; P&lt; 0.01), while tri-tip and loin did not differ in lipid content (8.24 vs. 6.99 %; P &gt;0.05). Loin was ranked by the trained panel to have the highest overall tenderness, while tri-tip and heel did not differ in overall tenderness (P &gt;0.05). The overall tenderness value for heel was positively correlated with troponin-T degradation (P&lt; 0.01). On the other hand, overall tenderness value for loin was negatively correlated with lipid content (P&lt; 0.05), and overall tenderness value for tri-tip was negatively correlated with collagen content (P&lt; 0.05). These results indicated that each beef cut had a unique profile of tenderness contributors.

A Proposed Mechanism for Texture Property of Woody Breast in Broilers

ObjectivesWoody breast is a myopathy observed in chicken breast meat (Pectoralis major) characterized by its tough and rubbery texture. However, the exact causation of woody breast texture is still unknown. We hypothesize that sarcoplasmic reticulum (SR) dysfunctionality early postmortem results in rapid leakage of intracellular calcium may partially contribute to the abnormal meat texture observed in woody breast meat. The objective of this preliminary study was to investigate this hypothesis.Materials and MethodsFourteen Ross line broiler breast fillets (7 severe woody breast and 7 normal) were collected at 3 h postmortem from a commercial processing plant located in the southeast United States. The 7 woody breast samples also exhibited moderate to severe white striping. The 7 normal samples did not exhibit any signs of white striping or woody breast. Each sample was trimmed, weighed, vacuum packaged and frozen at –20°C at approximately 8 h postmortem. One 1.9 cm strip across the cranial end of each fillet was fabricated and pulverized in liquid nitrogen to measure sarcomere length (Laser Scan Confocal Microscope with a 100x/NA 1.4 objective), calpain activity (immunoblotting for µ-calpain autolysis), proteolysis (immunoblotting for troponin-T degradation) and collagen content (hydroxyproline content). Purge was also collected from each sample to evaluate protein (bicinchoninic acid assay) and free calcium concentration (atomic absorption).ResultsWoody breast fillets were heavier than normal chicken breast fillets (522.9 vs. 446.9g; P < 0.05). Woody breast samples tended to have shorter sarcomeres (1.70 vs. 2.02 µm; P = 0.0543) and less intact troponin-T compared to normal breast samples (relative intact troponin-T band density: 49.98 vs. 56.97%; P = 0.0515) at 8 h postmortem. It was interesting to note that no µ-calpain band was detected through immunoblotting for both the woody breast and normal samples at 8 h postmortem. Other studies have found similar results as poultry µ-calpain autolyzed at a much rapid rate than µ-calpain in mammalian species. In addition, the purge from woody breast samples also had higher levels of free calcium compared to normal samples (6.2 vs. 4.2 nmol calcium/mg protein; P < 0.05). Lastly, there was more collagen present in the woody breast samples compared to normal chicken breast samples (3.89 vs. 2.08 mg collagen/g muscle tissue; P < 0.05).ConclusionThe results indicated that the cause of texture abnormality of woody breast may be the combined effects of more calcium being released from the SR early postmortem resulting in shorter sarcomere length and more collagen being deposited in the chicken breast meat. Additional research with the focus on SR integrity and functionality as well as collagen crosslinks are needed to further elucidate the basic mechanism of woody breast texture formation.

Determination of Chlormequat and Mepiquat in Foods by Liquid Chromatography/Mass Spectrometry or Liquid Chromatography/Tandem Mass Spectrometry: Interlaboratory Study

Interlaboratory validation studies have been performed on 2 methods for the determination of chlormequat (CLQ) and mepiquat (MPQ). Both methods used identical extraction procedures and stable isotope internal standardization but differed in the use of liquid chromatography/mass spectrometry (LC/MS) or LC/tandem mass spectrometry (LC/MS/MS) for the determination, the amount of internal standard used, and the expected limit of detection. After addition of deuterated internal standards, CLQ and MPQ were extracted with methanol–water and determined by LC/MS or LC/MS/MS with positive electrospray ionization. Eight European laboratories participated in the LC/MS method study, analyzing mushroom, pear, wheat flour, and fruit puree with residues of CLQ in the range 0.040–1.19 mg/kg and of MPQ in the range 0.041–0.39 mg/kg. For CLQ, the Horwitz ratio (HoRat) values for individual test materials/levels were in the range 0.85–1.13 with amean of 1.00, showing good method performance. For MPQ, the Ho values for mushroom, pear (both levels), and wheat flour were in the range 0.83–0.94, again indicating good method performance. For the determination of MPQ in infant food (fruit puree) at 0.041 mg/kg, the Ho was 1.7 when a value of 0 reported by one participant was excluded. In the LC/MS/MS study, in which 11 laboratories participated, a separate sample set was analyzed with residues of CLQ in the range 0.007–1.03 mg/kg and of MPQ in the range 0.008–0.72 mg/kg. Ho values for CLQ were in the range 0.27–1.36 and for MPQ in the range 0.51–2.10, all corresponding to acceptable method performance.

Reconstitution of the CD45RO(+) and CD20(+) lymphoid marrow population following allogeneic bone marrow transplantation for Ph(+) CML

Following bone marrow transplantation (BMT) investigations on the recovery of the B and T lymphocyte populations have focused on the peripheral blood and only marginally regard the bone marrow. An immunohistochemical and morphometric study was performed on 352 trephine biopsies derived from 123 patients with chronic myelogenous leukemia (CML) at standardized endpoints before and after allogeneic BMT and compared to a control group. The purpose of this investigation was to quantify the B-CD20(+) and T-CD45RO(+) lymphocyte subsets and to determine possible relationships with the occurrence of acute and chronic GVHD. Moreover, we studied the dynamics of lymphocyte repopulation in the post-transplant period, correlations with the total peripheral lymphocyte count and differences associated with sibling vs alternate HLA-compatible (unmanipulated) marrow grafts. Morphometric analysis revealed a very fast regeneration of CD45RO(+) and CD20(+) marrow lymphocytes in the first 2 weeks following BMT. In less than 2 months, in most patients, the post-transplant quantity of lymphocytes was comparable to that of the normal bone marrow. This finding was opposed to the profound depression of the absolute lymphocyte count in the peripheral blood. No relevant relationships could be calculated between engraftment status and the lymphocyte repopulation in the bone marrow. On the other hand, significant correlations were calculable between the development of (chronic and acute) GVHD including severity with the number of CD45RO(+) lymphocytes. In non-related graft constellations a more frequent evolution of acute grade III + IV GVHD was detectable. This complication was accompanied by an increased quantity of CD45RO(+) lymphocytes in the marrow.

Effects of a new oral contraceptive containing an antimineralocorticoid progestogen, drospirenone, on the renin-aldosterone system, body weight, blood pressure, glucose tolerance, and lipid metabolism

Combined hormonal oral contraceptives (OCs) may lead to a mild rise in blood pressure and body weight. In rare instances, large increments in blood pressure are measured. We investigated the effect of a combination of ethinyl estradiol (EE) plus a progestogen with antimineralocorticoid, i.e. natriuretic, properties [Drospirenone (DRSP)] on body weight, blood pressure, the renin-aldosterone system, atrial natriuretic factor, plasma lipids, and glucose tolerance. It is anticipated that this will lead to the development of an OC that does not raise body weight or blood pressure. Four groups of 20 women each received 30 micrograms EE plus 3 mg DRSP (group A), 20 micrograms EE plus 3 mg DRSP (group B), 15 micrograms EE plus 3 mg DRSP (group C), and, as a control OC, 30 micrograms EE plus 150 micrograms levonorgestrel (Microgynon, Schering; group D) for 6 months. During the OC-free control cycles before and after treatment and throughout treatment, the target parameters were measured. Between the pretreatment cycle and the sixth treatment cycle, mean body weight fell by 0.8 to 1.7 kg in groups A, B, and C (P < 0.05 vs. D), whereas it rose by 0.7 kg in group D. Systolic and diastolic blood pressures fell by 1-4 mm Hg in groups A, B, and C (significant for A and C vs. D) and increased by 1-2 mm Hg in group D. Renin substrate rose equally in all groups (P < 0.05), whereas PRA and plasma aldosterone rose significantly only in the DRSP groups, presumably due to sodium loss. In the DRSP groups, high density lipoprotein cholesterol rose (P < 0.05), in contrast to group D. Low density lipoprotein cholesterol fell slightly (P > 0.05), whereas triglyceride levels showed a stronger increase in the DRSP groups (P < 0.05) than in group D. All groups attained good cycle control; group A had the best. Side-effects were minimal. To our knowledge, this is the first report on a combined OC that leads to a small decrease in body weight and blood pressure. It may be especially beneficial for women susceptible for a gain in weight and a rise in blood pressure.

Iron status in runners of various running specialties

The blood iron status of 44 male runners of various running specialties (18 sprinters, 13 middle- and 13 long-distance runners) is evaluated by measuring serum ferritin (SF), serum iron (Si), hemoglobin concentration (Hb), hematocrit (Ht), red blood cells content (RBC) and haptoglobin concentration (Hp). The results of these analyses (except Hp) are compared to those obtained in sedentary male subjects (control group) of the same mean age. Mean SF, SI, Hb and Ht measured in athletes are significantly lower than in control group. The remarkably low Hp values obtained in athletes suggests the occurrence of hemolysis. Using unpaired t test, it appears that the blood iron status of these runners does not depend on their running specialty.