Insoluble Collagen Research Articles

The influence of diet on collagen content and quality attributes of infraspinatus muscle from Holstein–Friesian young bulls

The aim of the study was to determine effects of feeding intensity on collagen content and eating quality of infraspinatus (INF) muscle. Twenty Polish Holstein-Friesian bulls (11-month-old) were fed either intensively (I, n=10, with triticale meal addition to total mixed ration) or semi-intensively (SI, n=10, without triticale meal) before slaughter at 19months. The animals from I group showed higher body weight at the end of fattening, average daily gain and dressing percentage than SI group. The INF muscle from I treatment had higher fat content and the proportion of water-soluble collagen, whereas lower insoluble collagen content compared with SI treatment. There were no differences in shear force values, cooking loss and eating quality between the treatments. In conclusion, feeding Holstein-Friesian bulls with increased energy value fodder beneficially affected its slaughter value and collagen profile in infraspinatus muscle.

Differential impact of mechanical unloading on structural and nonstructural components of the extracellular matrix in advanced human heart failure

Adverse remodeling of the extracellular matrix (ECM) is a significant characteristic of heart failure. Reverse remodeling of the fibrillar ECM secondary to mechanical unloading of the left ventricle (LV) by left ventricular assist device (LVAD) has been subject of intense investigation; however, little is known about the impacts on nonfibrillar ECM and matricellular proteins that also contribute to disease progression. Explanted failing hearts were procured from patients with nonischemic dilated cardiomyopathy (DCM) with or without LVAD support, and compared to nonfailing control hearts. LVfree wall specimens were formalin-fixed, flash-frozen or optimum cutting temperature-mount frozen. Histologic and biochemical assessment of fibrillar ECM showed that LVAD support was associated with lower levels of insoluble collagen, collagen type I mRNA, and collagen I/III ratio compared with no-LVAD hearts. Adisintegrin and Metalloproteinase with Thrombospondin Motifs-2 (ADAM-TS2), aprocollagen endopeptidase, was reduced in no-LVAD but not in LVAD hearts. The rise in ECM proteolytic activities was significantly lower in LVAD hearts. Matrix metalloproteinases (MMP1, MMP2, MMP8, MMP13, and MT1-MMP/MMP14) were comparable between DCM hearts. Tissue inhibitor of metalloproteinase (TIMP)3 and TIMP4 messenger RNA and protein showed the greatest reduction in no-LVAD hearts. Basement membrane proteins exhibited less severe disarray of laminin and fibronectin-1 in LVAD-supported hearts. The rise in matricellular protein, osteopontin, was suppressed in LVAD hearts, whereas secreted protein, acidic, cysteine-rich (SPARC) levels was unaffected by LVAD. Mechanical unloading of the failing DCM hearts can restore the fibrillar ECM and the basement membrane, contributing toward improved clinical outcomes. However, persistent elevation of matricellular proteins such as SPARC could contribute to the relapse of failing hearts on removal of LVAD support.

Effect of growth-promoting technologies on Longissimus lumborum muscle fiber morphometrics, collagen solubility, and cooked meat tenderness.

The objective of the study was to examine the effect of growth-promoting technologies (GP) on Longissimus lumborum steak tenderness, muscle fiber cross-sectional area (CSA), and collagen solubility. Crossbred feedlot heifers ( = 33; initial BW 464 ± 6 kg) were blocked by BW and assigned to 1 of 3 treatments: no GP (CON; = 11); implant, no zilpaterol hydrochloride (IMP; = 11); implant and zilpaterol hydrochloride (COMBO; = 11). Heifers assigned to receive an implant were administered Component TE-200 on d 0 of the study, and the COMBO group received 8.3 mg/kg DM of zilpaterol hydrochloride for the final 21 d of feeding with a 3 d withdrawal period. Following harvest, strip loins were collected and fabricated into 4 roasts and aged for 3, 14, 21, or 35 d postmortem. Fiber type was determined by immunohistochemistry. After aging, objective tenderness and collagen solubility were measured. There was a treatment × day of aging (DOA) interaction for Warner-Bratzler shear force (WBSF; < 0.01). At d 3 of aging, IMP and COMBO steaks had greater WBSF than CON steaks ( < 0.01). By d 14 of aging, the WBSF of IMP steaks was not different ( = 0.21) than CON steaks, but COMBO steaks had greater shear values than steaks of other treatments ( < 0.02). The COMBO steaks only remained tougher ( = 0.04) than the CON steaks following 35 DOA. Compared to CON muscles, IMP and COMBO type I and IIX muscle fibers were larger ( < 0.03). Treatment, DOA, or the two-way interactions did not impact measures of total and insoluble collagen ( > 0.31). Soluble collagen amount tended to be affected ( 0.06) by a treatment × DOA interaction which was due to COMBO muscle having more soluble collagen than the other 2 treatments on d 21 of aging ( < 0.02). Correlation analysis indicated that type I, IIA, and IIX fiber CSA are positively correlated with WBSF at d 3 and 14 of aging ( < 0.01), but only type IIX fibers are correlated at d 21 and 35 of aging ( < 0.03). At these time periods, total and insoluble collagen became positively correlated with WBSF ( < 0.01). This would indicate that relationship between muscle fiber CSA and WBSF decreases during postmortem aging, while the association between WBSF and collagen characteristics strengthens. The use of GP negatively impacted meat tenderness primarily through increased muscle fiber CSA and not through altering collagen solubility.

The influence of crossbreeding on collagen solubility and tenderness of Infraspinatus and Semimembranosus muscles of semi-intensively reared young bulls.

The aim of the present study was to investigate the effects of crossbreeding on collagen content and solubility, shear force (WBSF) and the eating quality of Infraspinatus (INF) and Semimembranosus (SM) muscles of young bulls and the relationships between collagen content and solubility, shear force and the eating quality of beef. The experimental material comprised muscles of crossbred young bulls (about 600 days old) of Polish Holstein-Friesian (PHF) × Limousine (LM) (n = 10), PHF × Charolaise (CH) (n = 9), PHF × Hereford (HER) (n = 9) breeds. The crossbreeding influenced WBSF, aroma and taste, total, water-soluble, acid-soluble, total soluble and insoluble collagen content, as well as the acid-soluble, total soluble and insoluble collagen proportions. WBSF was significantly negatively correlated with sensorial tenderness and water-soluble collagen content. The eating quality of beef obtained from different crossbreds was similar; however, the meat from PHF × LM and PHF × HER bulls had lower WBSF values than PHF × CH bulls. © 2016 Japanese Society of Animal Science.

Effect of carboidiimide on thermal denaturation temperature of dentin collagen

Objectives1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) has been shown to cross-link dentin type I collagen. Increased cross-linking usually elevates the glass transition temperature of polymers. The aim of this study was to evaluate the cross-linking reaction promoted by EDC in different aqueous concentrations by measuring the thermal denaturation temperature (Td) of human dentin collagen. MethodsThe Td of dehydrated collagen and of insoluble dentin matrix collagen immersed in 0.5M or 1M EDC aqueous solution for different treatment times was obtained using a Differential Scanning Calorimeter (DSC). Specimens were also analyzed by Energy Dispersive X-Ray Spectroscopy. ResultsEDC-treated dentin collagen showed a significantly higher Td than the untreated specimens when immersed in either 0.5M EDC or 1M EDC for 10min or longer (p<0.05). EDC-treated dentin collagen showed an increase of sulfur and chloride, not detectable in EDC-untreated dentin specimens. Conversely, the relative amount of carbon, nitrogen and oxygen was not modified by treatments. SignificanceEDC-treated dentin collagen showed a higher Td than the untreated control at all tested concentrations and immersion times. A higher Td can be considered an indirect indicator of a more resistant and highly cross-linked collagen network. More data are needed to confirm these results.

Free standing collagen films prepared by electrophoretic deposition

Event Abstract Back to Event Free standing collagen films prepared by electrophoretic deposition David Barrett1, Terance Hart2, Serena Best1 and Ruth Cameron1 1 University of Cambridge, Department of Materials Science and Metallurgy, United Kingdom 2 Geistlich Pharma Ag, Switzerland Introduction: Electrophoretic deposition is a widely used technique in the ceramic industries for forming coatings and structures with reproducible properties and of arbitrary shape and size. It works by applying an electric field to a solid suspension of charge particles. The particles feel the field and experience a force that moves them towards one of the electrodes, which when reached leads to a deposit or film on the surface of the electrode, the properties of which can be set by altering parameters such as the applied field strength and the conductivity of the suspension. Recently there has been interest in the literature towards using the electrophoretic deposition technique with a wider variety of materials such as polymers and biomaterials[1]. In this study we have applied the technique of electrophoretic deposition to proteins to produce films for use in a variety of roles. These films can be removed from the electrodes after deposition and are self-supporting. Materials and Methods: Insoluble collagen I was rehydrated using 0.05M acetic acid and ethanol was added to 50 vol%. The suspension was then homogenised until a smooth consistency was achieved. Stress – strain data was determined by using a TA Instruments Q800 DMA operating in constant tensile stress ramping mode. SEM images were obtained by sputter coating the samples with gold and imaging with a JEOL 5800 LV SEM in secondary electron mode. Deposition was carried out using custom built deposition apparatus and consisted of two 304L steel plates separated by silicone spacers that could be adjusted to change the electrode spacing. The electric field was produced with a TGA1241 Arbitrary Waveform Generator (TTI) and was applied as either a series of pulses of varying length, between 1ms and 1s, or as a continuous. The voltage applied was fixed at 5V. Results and Discussion: Figure 1. Free standing collagen films Figure 1 shows an three films produced by the electrophoretic deposition of collagen demonstrating a range of different sizes and thicknesses of deposited films. They are macroscopically defect free and could be easily separated from the electrodes they were deposited onto. Figure 2. Stress-strain curve for collagen film with 1 or 2 layers Figure 2 shows the reproducible nature of the mechanical properties of collagen films produced by electrophoretic deposition and shows that delamination does not occur between layers deposited onto each other. The average UTS was found to be 47.4±3.3MPa for a single layer and 46.8±3.6MPa for a double layer of collagen. These values are comparable with those for collagen films produced by other techniques such as solvent casting[2]. Figure 3. SEM (left) and AFM (right) images of a collagen film Figure 3 shows representative SEM and AFM images confirming the defect free nature of the films produced. Small features approximately 5μm can be seen where gas bubbles have formed during film formation but the films are smooth overall with an average roughness Rq(RMS)= 287±90nm. Conclusion: This study has shown that electrophoretic deposition can be used as a technique to reliably produce free standing films of collagen rapidly and without macroscopic defects. These films have mechanical properties that match those of films produced by other techniques and can be produced in a range of sizes and thicknesses. They have low surface roughness values and show homogeneous microstructure. The authors would like to thank the EPSRC (Grant no: EP/L504920/1) and Geistlich Pharma AG for providing financial support to this project.

Myocardial Collagen Cross-Linking Is Associated With Heart Failure Hospitalization in Patients With Hypertensive Heart Failure

BackgroundExcessive myocardial collagen cross-linking (CCL) determines myocardial collagen’s resistance to degradation by matrix metalloproteinase (MMP)-1 and interstitial accumulation of collagen fibers with impairment of cardiac function. ObjectivesThis study sought to investigate whether CCL and a newly identified biomarker of this alteration are associated with hospitalization for heart failure (HHF) or cardiovascular death in patients with HF and arterial hypertension in whom other comorbidities were excluded. MethodsEndomyocardial biopsies and blood samples from 38 patients (invasive study), and blood samples from 203 patients (noninvasive study) were analyzed. Mean follow-ups were 7.74 ± 0.58 years and 4.72 ± 0.11 years, respectively. Myocardial CCL was calculated as the ratio between insoluble and soluble collagen. The ratio between the C-terminal telopeptide of collagen type I (CITP) and matrix metalloproteinase-1 (CITP:MMP-1) was determined in blood samples. ResultsInvasive study: CCL was increased (p < 0.001) in patients compared with controls. Patients were categorized according to normal or high CCL values. Patients with high CCL exhibited higher risk for subsequent HHF (log-rank test p = 0.022), but not for cardiovascular death. CITP:MMP-1 was inversely associated with CCL (r = −0.460; p = 0.005) in all patients. Receiver operating characteristic curves rendered a CITP:MMP-1 cutoff ≤1.968 (80% sensitivity and 76% specificity) for predicting high CCL. Noninvasive study: Patients were categorized according to CITP:MMP-1 ratio values as normal ratio (>1.968) or low ratio (≤1.968). Patients with a low ratio exhibited higher risk for HHF (log-rank test p = 0.014), which remained significant after adjustment for relevant covariables (adjusted hazard ratio: 2.22; 95% CI: 1.37 to 3.59, p = 0.001). In addition, CITP:MMP-1–based categorization yielded significant integrated discrimination and net reclassification improvements (p = 0.003 and p = 0.009, respectively) for HHF over relevant risk factors. CITP:MMP-1 was not associated with the risk of cardiovascular death. ConclusionsExcessive myocardial CCL is associated with HHF in hypertensive patients with HF. In this population, the serum CITP:MMP-1 ratio identifies patients with increased CCL and high risk of HHF.

Protease with collagenolytic activity produced by Bacillus sp. DPUA 1728 from Amazonian soil.

Qualitative analyses were carried out on solid medium with insoluble collagen 0.25% (w/v) to detect proteases with collagenolytic activity produced by Bacillus sp. In cultures incubated for 24 h, a 23 full factorial design with four repetitions at the center point was developed to analyze the effects and interactions between initial pH, temperature and the concentration of gelatin. Based on the results of the first 23 full factorial design, a successive 23 full factorial design was performed. The most favorable production conditions were found to be 1.5% (w/v) gelatin, pH 9.0 and 37 °C with enzymatic activity of 86.27 U/mL. The enzyme showed optimal activity at 50 °C and pH 9.0, and it was stable over wide pH (7.2-10.0) and temperature (45 °C-60 °C) ranges. These results indicate that Bacillus sp DPUA 1728 is a potential source for producing collagenolytic protease with possible biotechnological applications, such as in the food, cosmetics and leather industries.

Abstract 16611: Impact of Mechanical Unloading on Structural and Non-structural Components of the Extracellular Matrix in Patients With Dilated Cardiomyopathy

Introduction: Extracellular matrix (ECM) is the non-cellular component of the myocardium and its remodeling in cardiomyopathy is a major contributor to disease outcomes. While the impact of left ventricular assist device (LVAD) on remodeling of fibrillar ECM has been studied, its effects on the non-fibrillar ECM and matricellular proteins within the ECM that can influence cardiac structure and function are unknown. Hypothesis: Mechanical unloading preserves the non-fibrillar ECM composition, thereby contributing to reversal of adverse myocardial remodeling. Methods: Hearts were obtained from heart failure patients with idiopathic dilated cardiomyopathy (DCM) with LVAD support (&gt;3mths; LVAD), without LVAD (no-LVAD), and non-failing control hearts (NFC) (n=10/group). LV free wall were fixed or flash-frozen for molecular and IHC evaluations. Results: Assessment of fibrillar ECM showed greater total and insoluble collagen content in no-LVAD hearts, consistent with an increase in collagen type I mRNA, and collagen type I-to-type III ratio. Proteolytic activities (collagenase &amp; gelatinase) were significantly higher in no-LVAD (by 45% and 40%) suggesting greater ECM turnover in these hearts. TIMP1 mRNA decreased in both DCM groups (by 60%), but its protein decreased only in no-LVAD hearts (by 30%). TIMP3 and TIMP4 mRNA (by 30% and 55%) and protein (by 60% and 55%) decreased in both LVAD and no-LVAD hearts. ADAM-TS2, the N-terminal endopeptidase for collagen, was markedly lower in no-LVAD, while LOX1, the cross-linking enzyme showed a small increase in no-LVAD hearts. Evaluation of the basement membrane revealed that laminin arrangements were dispersed in no-LVAD hearts. Integrin β1, a cardiomyocyte cell-surface receptor for laminin, was reduced in no-LVAD but preserved in LVAD hearts. Other basement membrane proteins (fibronectin-1, collagen IV) showed similar trends, whereas differences in matricellular proteins (osteopontin, SPARC) were less striking between LVAD and no-LVAD hearts. Conclusions: Mechanical unloading positively impacts multiple aspects of myocardial ECM, the fibrillar ECM network and the less explored basement membrane, although the matricellular proteins residing within the ECM seem to be less affected.

Amino acid profile of collagen fractions extracted from by-products of Ophistonema libertate and Scomber japonicus

The objective of this study was to identify the amino acid profile (AAp) of collagen extracted from Ophistonema libertate and Scomber japonicus head:tail homogenates. Salt (SSC)-, acid (ASC)-, and pepsin (PSC)-soluble collagens and insoluble collagen (IC) were extracted by solubility. The homogenates of both species exhibited high concentrations of proline, aspartic acid, glutamic acid, arginine, histidine, and hydroxyproline. Higher concentrations of aspartic acid and lysine were registered in S. japonicus SSC compared with O. libertate. S. japonicus PSC showed significantly higher concentrations for most of the amino acids (AAs) evaluated compared with O. libertate, including aspartic acid, glutamic acid, serine, glycine, alanine, tyrosine, proline, hydroxyproline, arginine, threonine, methionine, valine, phenylalanine, isoleucine, leucine, lysine, and histidine. Hydroxyproline showed no significant differences among both species homogenates; however, O. libertate IC was higher than S. japonicus IC. Differences detected in the AAp of both species could suggest different properties of the collagen extracted.

Correlation of fresh muscle firmness with sensory characteristics of pork loins destined for a quality focused market.

Production of pork for quality-driven export markets offers economic incentive. Pork processors use subjective firmness as a sorting tool for loins intended for high-quality export. The objectives of this study were to determine 1) durometer efficacy in muscle, 2) if firmness on one portion of the loin is indicative of other locations, 3) if 1 d firmness is related to export quality traits, and 4) if variation in firmness is explained by mechanistic measures. Subjective firmness scores (1 = extremely soft and 5 = extremely firm) were determined by a trained individual 1 d (initial time point) postmortem. Loins (North American Meat Processors number 414 Canadian back; = 154) were wet aged for 28 d at 1.7°C. On d 28, a panel of 4 individuals assigned firmness scores on the ventral side of the loin at the area of the 10th rib, the anterior half, and the posterior half of the loin. Durometer readings were collected at the area of the 10th rib on the dorsal and ventral side of the loin. Spearman correlation coefficients were computed in SAS (version 9.3) to account for nonnormality of categorical data. Subjective firmness measurements at d 28 at the 10th rib and on the anterior portion of the loin were not correlated ( ≥ 0.21) with whole loin durometer readings on the dorsal or ventral portion of the loin or the average of the whole loin values. Subjective firmness (d 28) at the 10th rib accounted for 38.44 ( = 0.620) and 48.30% ( = 0.695) of the variation in firmness at the anterior portion of the loin and the posterior portion of the loin, respectively ( ≤ 0.05). One-day subjective firmness measurements were correlated with 28-d Warner-Bratzler shear force measurements ( = 0.174, = 0.03) but were not significantly correlated with sensory characteristics ( ≥ 0.08). Purge tended to be correlated with 1 d firmness ( = 0.136, = 0.10); however, drip and cooking loss, 24-h and 28-d pH, and soluble and insoluble collagen content were not correlated ( ≥ 0.34). Firmness measurements collected in the production facility (1 d) were negatively correlated with iodine value (IV; = -0.199, = 0.02), yet no 28-d subjective firmness measurements were correlated with IV ( ≥ 0.33). When loins not achieving export standards are removed from the population, 1 d firmness was not correlated to export quality or sensory characteristics (d 28). Differences in firmness were not explained by mechanistic measures. Inconsistencies among subjective and objective firmness measurements suggest that the durometer may not be an appropriate way to determine firmness.

Human cathepsin L, a papain-like collagenase without proline specificity.

Several members of the papain-like peptidase family have the ability to degrade collagen molecules by cleaving within the triple helix region of this difficult substrate. A common denominator of these peptidases is their ability to cleave substrates with Pro in the P2 position. In humans, cathepsin K is the best-known papain-like collagenase. Here, we investigate the collagenolytic activity of human cathepsin L, which is closely related to cathepsin K. We show that, despite lacking proline specificity, cathepsin L efficiently cleaves type I collagen within the triple helix region and produces a cleavage pattern similar to that of cathepsin K. We demonstrate that both enzymes have similar affinities for type I collagen and are able to release proteolytic fragments from insoluble collagen. Moreover, cathepsin K is only approximately fourfold more potent than cathepsin L in releasing fragments from reconstituted fibrils of FITC-labeled collagen. Replacing active site residues of cathepsin L with those from cathepsin K introduces cathepsin K-like specificity towards synthetic substrates and increases the collagenolytic activity of cathepsin L. Replacing three residues in the S2 subsite is sufficient to produce a mutant with collagenolytic activity on par with human cathepsin K. These results provide a basis for engineering collagenolytic activity into non-collagenolytic papain-like scaffolds.

Collagen from jumbo squid fin: extracting conditions and influence of the protease system on collagen hydrolysate antioxidant activity

The optimal alkaline and acid conditions for insoluble collagen extraction from jumbo squid fin (JSF) were established by factorial analysis. Dependent variable: protein concentration; independent variables: NaOH and HCl concentrations. The antioxidant properties of JSF collagen hydrolysates obtained by two protease systems were studied. Moreover, jumbo squid skin (JSS) collagen was obtained and hydrolysated under optimal conditions. The optimal extraction condition was 0.5 M NaOH followed by 0.2 M HCl. Collagen α-chains were detected in both JSF and JSS. Collagen β-component was detected only in JSS. JSS collagen showed higher levels of polar and hydrophobic amino acids. The JSF hydrolysates produced by subtilisin showed a lower degree of hydrolysis and higher antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), and oxygen radical absorbance capacity-fluorescein (ORACFL)) than those produced by a mixture of trypsin, chymotrypsin, and peptidase. The JSS hydrolysates showed a higher antioxidant capacity. We have thus established a suitable process to improve the utility of JSF.

Effects of breed, muscle type, and frozen storage on physico-chemical characteristics of lamb meat and its relationship with tenderness

The effects of breed, muscle types, and frozen storage time on the physico-chemical characteristics of the two most important China breeds were considered. Twenty-four lambs of Bashbay and Xinjiang Merino sheep of 7–9 months old were slaughtered, respectively, and frozen for 1, 7, 15, or 30 days. The meat pH, water holding capacity (WHC), intramuscular fat, cooking loss, myofibrillar fragmentation index (MFI), moisture, shear force (SF), and connective tissue were measured at 24 h postmortem. These physico-chemical characteristics varied with breed and muscle types. Xinjiang Merino had a higher pH (P < 0.001) than Bashbay. M. supraspinatus had a higher pH (P < 0.001) compared to the M. gluteus and M. longissimus dorsi. The total and insoluble collagen and intramuscular fat were higher in Xinjiang Merino. As the time of frozen storage increased from 1 to 15 days, the intramuscular fat, cooking loss, WHC, and MFI in Xinjiang Merino increased gradually. SF and tenderness were improved.

Comparison of Carcass and Sensory Traits and Free Amino Acid Contents among Quality Grades in Loin and Rump of Korean Cattle Steer.

This study was performed to compare carcass traits, sensory characteristics, physiochemical composition, and contents of nucleotides, collagen, and free amino acids among quality grades (QG) and to understand the association between QG and above parameters in loin and rump of Korean cattle steer. Loin and rump samples were obtained from 48 Korean cattle steers with each of four QG (QG 1++, 1+, 1, and 2; average 32 months of age). Carcass weight and marbling score (MS) were highest in QG 1++, whereas texture score measured by a meat grader was highest in QG 2. A correlation analysis revealed that MS (r = 0.98; p<0.01) and fat content (r = 0.73; p<0.01) had strong positive correlations with QG and that texture had a strong negative correlation (r = −0.78) with QG. Fat content in loin was highest but protein and moisture contents were lowest in QG 1++. Our results confirmed that a major determinant of QG is the MS; thus, intramuscular fat content. The International Commission on Illumination L*, a*, and b* values in loin were highest in QG 1++. Numeric values of shear force in loin were lowest in QG 1++, whereas those of tenderness, juiciness, and overall acceptability tended to be highest in QG 1++ without statistical significance. QG was strongly correlated with juiciness (r = 0.81; p<0.01) and overall acceptability (r = 0.87; p<0.001). All sensory characteristics were higher (p<0.05) in loin than those in rump. Adenosine-5′-monophosphate (AMP) and inosine-5′-monophosphate (IMP) contents in both loin and rump did not differ among QGs. No nucleotide (AMP, IMP, inosine, hypoxanthine) was correlated with any of the sensory traits. Total, soluble, and insoluble collagen contents in loin were higher in QG 1++ than those in QG 1. All three collagens had lower content in loin than that in rump. All three collagens were positively correlated with tenderness, juiciness, and overall acceptability. Glutamic acid content did not significantly differ among the four QGs in either loin or rump. In conclusion, it is confirmed that QG is associated with sensory traits but nucleotide contents in beef may not be a major factor determining meat palatability in the present study.

The influence of post-mortem conditioning on the tenderness of Egyptian goose (Alopochen aegyptiacus) breast meat (M. pectoralis major).

Egyptian goose breast meat has been found to be very tough compared to the meat of other well-known fowl species. In attempting to clarify the toughness of the meat, the physical and biochemical changes during post-mortem conditioning (14 days) was investigated. Although there was increased cathepsin (B, B & L and H) activity, together with a decrease (P ≤ 0.05) in myofibrillar fragmentation lengths (32-25 µm) with conditioning, no change (decline) in shear force values was observed. The higher (P ≤ 0.05) shear force of the male breast portions may be linked to the higher (P ≤ 0.05) concentrations of total and insoluble collagen. No significant change (decline) in shear force values was observed. Conditioning of Egyptian goose meat as a means of improving the overall toughness cannot therefore not be proposed. The higher shear force and lower sensory tenderness of the male breast portions, as previously observed, may be linked to higher concentrations of total and insoluble collagen.

Effects of Ultrasound Treatment on Connective Tissue Collagen and Meat Quality of Beef Semitendinosus Muscle

AbstractThe effects of low‐frequency, high‐power ultrasound (40 kHz, 1,500 W) on meat quality and connective tissue collagen of beef semitendinosus muscle were assessed. Beef steaks were sonicated for 10, 20, 30, 40, 50 or 60 min. The effects of ultrasound on exudate yield, water‐loss rate, cooking loss, meat tenderness, and connective tissue and collagen properties were assessed. The results revealed that ultrasound increased meat exudate and water‐loss rates and reduced Warner–Bratzler shear force values. However, ultrasound had no effect on cooking loss or insoluble collagen content and little effects on collagen content and solubility. The mechanical strength of connective tissue decreased in ultrasound‐treated beef samples. Following ultrasound treatment of ≥10 min, muscle fibers shrank, the endomysium was disrupted and the perimysium thickness decreased. Protein aggregates formed in the extracellular space. Low‐frequency, high‐power ultrasound had significant effects on meat texture and connective tissue properties.Practical ApplicationsIntramuscular connective tissue (IMCT) and collagen are related to meat quality, especially meat tenderness and texture. Ultrasound treatment enhances tenderness and sensory attributes of meat by changing cellular structures. However, there are limited data on the effectiveness of ultrasound on meat quality from the viewpoint of IMCT. In this study, we reported the meat quality attributes affected by changes in connective tissue and collagen as a result of ultrasound treatment. The results obtained in this study would be useful for the scientific community and the meat industry.

Human bone marrow stem cells cultured under hypoxic conditions present altered characteristics and enhanced in vivo tissue regeneration

Human bone marrow mesenchymal stem cells (hBMSCs) were isolated from bone marrow of the vertebral body. The hBMSCs were cultured under either hypoxic (1% O2) or normoxic (21% O2; control) conditions and the characteristics as mesenchymal stem cells were compared. Results revealed that hypoxia reduced proliferative potential and colony-forming efficiency of hBMSCs, and significantly enhanced osteogenic and chondrogenic differentiation. The hBMSCs enhanced the regenerative potential of bone in vivo. In vitro synthesis of soluble and insoluble collagen was significantly increased in the hypoxic condition. In vivo collagen tissue regeneration was also enhanced under the hypoxic condition, with concomitant increased expressions of various subtypes of collagen and lysyl-oxidase family mRNA. MicroRNA assays revealed that miR-155-5p, which negatively regulates HIF-1α, was significantly highly expressed. These observations demonstrate that hBMSCs obtained from human vertebrae exhibit altered characteristics under hypoxic conditions, and each factor contributing to hBMSC-mediated tissue healing should be evaluated with the goal of allowing their clinical application.

Lumican deficiency results in cardiomyocyte hypertrophy with altered collagen assembly

The ability of the heart to adapt to increased stress is dependent on the modification of its extracellular matrix (ECM) architecture that is established during postnatal development as cardiomyocytes differentiate, a process that is poorly understood. We hypothesized that the small leucine-rich proteoglycan (SLRP) lumican (LUM), which binds collagen and facilitates collagen assembly in other tissues, may play a critical role in establishing the postnatal murine myocardial ECM. Although previous studies suggest that LUM deficient mice (lum−/−) exhibit skin anomalies consistent with Ehlers–Danlos syndrome, lum−/− hearts have not been evaluated. These studies show that LUM was immunolocalized to non-cardiomyocytes of the cardiac ventricles and its expression increased throughout development. Lumican deficiency resulted in significant (50%) perinatal death and further examination of the lum−/− neonatal hearts revealed an increase in myocardial tissue without a significant increase in cell proliferation. However cardiomyocytes from surviving postnatal day 0 (P0), 1month (1mo) and adult (4mo) lum−/− hearts were significantly larger than their wild type (WT) littermates. Immunohistochemistry revealed that the increased cardiomyocyte size in the lum−/− hearts correlated with alteration of the cardiomyocyte pericellular ECM components collagenα1(I) and the class I SLRP decorin (DCN). Western blot analysis demonstrated that the ratio of glycosaminoglycan (GAG) decorated DCN to core DCN was reduced in P0 and 1mo lum−/− hearts. There was also a reduction in the β and γ forms of collagenα1(I) in lum−/− hearts. While the total insoluble collagen content was significantly reduced, the fibril size was increased in lum−/− hearts, indicating that LUM may play a role in collagen fiber stability and lateral fibril assembly. These results suggest that LUM controls cardiomyocyte growth by regulating the pericellular ECM and also indicates that LUM may coordinate multiple factors of collagen assembly in the murine heart. Further investigation into the role of LUM may yield novel therapeutic targets and/or biomarkers for patients with cardiovascular disease.

Circulation: Clinical Summaries.

Circulation: Clinical Summaries.