What is Comprehensive Geriatric Assessment (CGA)? An umbrella review.

Background: Comprehensive Geriatric Assessment (CGA) is now the accepted gold standard for caring for frail older people in hospital. However, there is uncertainty about identifying and targeting suitable recipients and which patients benefit the most. Objectives: our objectives were to describe the key elements, principal measures of outcome and the characteristics of the main beneficiaries of inpatient CGA. Methods: we used the Joanna Briggs Institute umbrella review method. We searched for systematic reviews and meta-analyses describing CGA services for hospital inpatients in the Cochrane Database of Systematic Reviews, Database of Reviews of Effectiveness (DARE), MEDLINE and EMBASE and a range of other sources. Results: we screened 1,010 titles and evaluated 419 abstracts for eligibility, 143 full articles for relevance and included 24 in a final quality and relevance check. Thirteen reviews, reported in 15 papers, were selected for review. The most widely used definition of CGA was: 'a multidimensional, multidisciplinary process which identifies medical, social and functional needs, and the development of an integrated/co-ordinated care plan to meet those needs'. Key clinical outcomes included mortality, activities of daily living and dependency. The main beneficiaries were people ≥55 years in receipt of acute care. Frailty in CGA recipients and patient related outcomes were not usually reported. Conclusions: we confirm a widely used definition of CGA. Key outcomes are death, disability and institutionalisation. The main beneficiaries in hospital are older people with acute illness. The presence of frailty has not been widely examined as a determinant of CGA outcome.

New horizons in comprehensive geriatric assessment.

In this article, we discuss the emergence of new models for delivery of comprehensive geriatric assessment (CGA) in the acute hospital setting. CGA is the core technology of Geriatric Medicine and for hospital inpatients it improves key outcomes such as survival, time spent at home and institutionalisation. Traditionally It is delivered by specialised multidisciplinary teams, often in dedicated wards, but in recent years has begun to be taken up and developed quite early in the admission process (at the 'front door'), across traditional ward boundaries and in specialty settings such as surgical and pre-operative care, and oncology. We have scanned recent literature, including observational studies of service evaluations, and service descriptions presented as abstracts of conference presentations to provide an overview of an emerging landscape of innovation and development in CGA services for hospital inpatients.

Effects of Added Zinc on Skeletal Muscle Morphometrics and Gene Expression of Finishing Pigs Fed Ractopamine-HCL.

Finishing pigs (n = 320) were used in a 35-day study to determine the effects of ractopamine-HCl (RAC) and supplemental Zinc (Zn) level on loin eye area (LEA) and gene expression. Pens were randomly allotted to the following treatments for the final 35 days on feed: a corn-soybean meal diet (CON), a diet with 10 ppm RAC (RAC+), and RAC diet plus added Zn at 75, 150, or 225 ppm. Sixteen pigs per treatment were randomly selected for collection of serial muscle biopsies and carcass data on day 0, 8, 18, and 32 of the treatment phase. Compared to CON carcasses, RAC+ carcasses had 12.6% larger (P = 0.03) LEA. Carcasses from RAC diets with added Zn had a tendency for increased (quadratic, P < 0.10) LEA compared to the RAC+ carcasses. Compared to RAC+ pigs, relative expression of IGF1 decreased with increasing levels of Zn on day 8 and 18 of treatment, but expression levels were similar on day 32 due to Zn treatments increasing in expression while the RAC+ treatment decreased (Zn quadratic × day quadratic, P = 0.04). A similar trend was detected for the expression of ß1-receptor where expression levels in the RAC+ pigs were greater than Zn supplemented pigs on day 8 and 18 of the experiment, but the magnitude of difference between the treatments was reduced on day 32 due to a decrease in expression by RAC+ pigs and an increase in expression by the Zn pigs (Zn quadratic × day quadratic, P = 0.01). The ability of Zn to prolong the expression of these two genes may be responsible for the tendency of Zn to increase LEA in RAC supplemented pigs.

Physical properties of cytoplasm.

The physical properties of cytoplasm differ considerably from dilute aqueous solutions. Recent research has improved our understanding of the properties of the fluid phase and provided a more detailed picture of cytoarchitecture and its relation to cytomechanics. Several recent holistic models indicate novel directions for future research.

Brownian motion of inert tracer macromolecules in polymerized and spontaneously bundled mixtures of actin and filamin.

By use of light microscopy and fluorescence photobleaching recovery, we have studied (a) structures that form in a system composed of copolymerized rabbit muscle actin and chicken gizzard filamin and (b) the Brownian motion of inert tracer macromolecules in this matrix. We have used as tracers size-fractionated fluorescein-labeled ficoll and submicron polystyrene latex particles. In F-actin solutions, the relative diffusion coefficient of the tracer was a decreasing function of both tracer size and actin concentration. Also, a percolation transition for latex particle mobility was found to follow a form suggested by Ogston (Ogston, A. G. 1958. Trans. Faraday Soc. 54:1754-1757) for random filament matrices. The inclusion of filamin before polymerization resulted in increased tracer mobility. Below a filamin dimer-to-actin monomer ratio of 1:140, no structural features were observed in the light microscope. At or above this ratio for all actin concentrations tested, a three-dimensional network of filament bundles was clearly discriminated. Latex particles were always excluded from the bundles. By use of a dialysis optical cell in which polymerization could be initiated with very little hydrodynamic stress, we found that filamin can spontaneously bundle F-actin. A simple physical picture explains how dynamics can affect the structural result of coassembly and provides a further hypothesis on the balance between random filament cross-linking and large-scale bundling. Control of this balance may be important in cytoplasmic motile events.

Probing the structure of cytoplasm.

We have used size-fractionated, fluorescent dextrans to probe the structure of the cytoplasmic ground substance of living Swiss 3T3 cells by fluorescence recovery after photobleaching and video image processing. The data indicate that the cytoplasm of living cells has a fluid phase viscosity four times greater than water and contains structural barriers that restrict free diffusion of dissolved macromolecules in a size-dependent manner. Assuming these structural barriers comprise a filamentous meshwork, the combined fluorescence recovery after photobleaching and imaging data suggest that the average pore size of the meshwork is in the range of 300 to 400 A, but may be as small as 200 A in some cytoplasmic domains.

Behavior of a fluorescent analogue of calmodulin in living 3T3 cells.

We have prepared and partially characterized a lissamine-rhodamine B fluorescent analogue of calmodulin, LRB-CM. The analogue had a dye/protein ratio of approximately 1.0 and contained no free dye or contaminating labeled proteins. LRB-CM was indistinguishable from native calmodulin upon SDS PAGE and in assays of phosphodiesterase and myosin light chain kinase. The emission spectrum of LRB-CM was insensitive to changes in pH, ionic strength, and temperature over the physiological range, but the apparent quantum yield was influenced somewhat by divalent cation concentration. LRB-CM injected into living Swiss 3T3 fibroblasts became associated with nitrobenzoxadiazole-phallacidin staining stress fibers in some interphase cells. LRB-CM and acetamidofluorescein-labeled actin co-injected into the same cell both became associated with fibers in some cells, but in most cases association of the two analogues with fibers was mutually exclusive. This suggests that calmodulin may differ from actin in the timing of incorporation into stress fibers or that we have distinguished distinct populations of stress fibers. We were able to detect no direct interaction of LRB-CM with actin by fluorescence photobleaching recovery (FRAP) of aqueous solutions. Interaction of LRB-CM with myosin light chain kinase also was not detected by FRAP. This suggests that the mean lifetime of the calmodulin-myosin light chain kinase complex is too short to affect the diffusion coefficient of calmodulin. We examined various fluorescent derivatives of proteins and dextrans as suitable control molecules for quantitative fluorescent analogue cytochemistry in living cells. Fluorescein isothiocyanate-dextrans were found to be preferable to all the proteins tested, since their mobilities in cytoplasm were inversely dependent on molecular size and there was no evidence of binding to intracellular components. In contrast, FRAP of LRB-CM in the cytoplasm of living 3T3 cells suggested that the analogue interacts with intracellular components with a range of affinities. The mobility of LRB-CM in the cytoplasm was sensitive to treatment of the cells with trifluoperazine, which suggests that at least some of the intracellular binding sites are specific for calmodulin in the calcium-bound form. FRAP of LRB-CM in the nuclei of living 3T3 cells indicated that the analogue was highly mobile within the nucleus but entered the nucleus from the cytoplasm much more slowly than fluorescein isothiocyanate-dextran of comparable molecular size and much more slowly than predicted from its mobility in cytoplasm.

Role of substrates and products of PI 3-kinase in regulating activation of Rac-related guanosine triphosphatases by Vav.

Mitogen stimulation of cytoskeletal changes and c-jun amino-terminal kinases is mediated by Rac small guanine nucleotide-binding proteins. Vav, a guanosine diphosphate (GDP)-guanosine triphosphate (GTP) exchange factor for Rac that stimulates the exchange of bound GDP for GTP, bound to and was directly controlled by substrates and products of phosphoinositide (PI) 3-kinase. The PI 3-kinase substrate phosphatidylinositol-4,5-bisphosphate inhibited activation of Vav by the tyrosine kinase Lck, whereas the product phosphatidylinositol-3,4,5-trisphosphate enhanced phosphorylation and activation of Vav by Lck. Control of Vav in response to mitogens by the products of PI 3-kinase suggests a mechanism for Ras-dependent activation of Rac.

A statistical approach for intensity loss compensation of confocal microscopy images.

In this paper, a probabilistic technique for compensation of intensity loss in confocal microscopy images is presented. For single-colour-labelled specimen, confocal microscopy images are modelled as a mixture of two Gaussian probability distribution functions, one representing the background and another corresponding to the foreground. Images are segmented into foreground and background by applying Expectation Maximization algorithm to the mixture. Final intensity compensation is carried out by scaling and shifting the original intensities with the help of parameters estimated for the foreground. Since foreground is separated to calculate the compensation parameters, the method is effective even when image structure changes from frame to frame. As intensity decay function is not used, complexity associated with estimation of the intensity decay function parameters is eliminated. In addition, images can be compensated out of order, as only information from the reference image is required for the compensation of any image. These properties make our method an ideal tool for intensity compensation of confocal microscopy images that suffer intensity loss due to absorption/scattering of light as well as photobleaching and the image can change structure from optical/temporal section-to-section due to changes in the depth of specimen or due to a live specimen. The proposed method was tested with a number of confocal microscopy image stacks and results are presented to demonstrate the effectiveness of the method.

In vitro supplementation with the porcine plasma product, betaGRO®, stimulates activity of porcine fetal myoblasts and neonatal satellite cells in a divergent manner.

Two separate experiments were conducted to evaluate the effect of betaGRO® supplementation on in vitro porcine fetal myoblasts (PFM) and porcine satellite cells (PSC) proliferation, fusion and myotube thickness. The PFM and PSC were isolated from the m. longissimus dorsi of day 60 of gestation fetuses and piglets within 24 h of birth, respectively. Proliferation assays were conducted as 4×3 factorial arrangements with time of culture (24, 48, 72, 96 h) and media treatment (standard porcine media supplemented with 10% (vol/vol) fetal bovine serum (HS); HS without 10% fetal bovine serum (LS); and LS supplemented with 10 mg/ml betaGRO® (BG)) as main effects. Fusion and myotube growth assays were conducted as 2×2 factorial designs with serum concentration (HS or LS), and betaGRO® inclusion (0 or 10 mg/ml) as main effects. There was a treatment×time interaction and betaGRO®×serum interactions for proliferation, fusion and myotube thickness of PFM (P<0.01). At all-time points, HS and BG-PFM had greater proliferation rates compared LS (P<0.01). The HS treatment had greater proliferation rates than BG (P<0.02) except at 72 h of culture (P=0.44). When betaGRO® was added to LS media, fusion percentage and myotube thickness decreased (P<0.01), while fusion percentage increased (P<0.01) and myotube thickness was unaffected (P=0.63) when betaGRO® was added to HS media. There were treatment×time and betaGRO®×serum interactions for proliferation rate and fusion rate of PSC, respectively (P<0.01). At all-time points, HS had greater proliferation rates than LS and BG (P<0.01), and LS had greater proliferation rates than BG (P<0.02). When betaGRO® was added to LS and HS media, fusion percentage increased for both media types (P<0.01). There was no betaGRO®×serum interaction (P=0.63) for PSC myotube thickness; however, betaGRO® supplemented myotubes were thicker (P<0.01) than non-betaGRO® supplemented myotubes. These two experiments indicate in vitro betaGRO® supplementation stimulates divergent responses based on the age of cell examined.

Phosphatidylinositol 4,5-bisphosphate induces actin-based movement of raft-enriched vesicles through WASP-Arp2/3.

BACKGROUND: Phosphatidylinositol 4,5-bisphosphate (PIP(2)) has been implicated in the regulation of the actin cytoskeleton and vesicle trafficking. It stimulates de novo actin polymerization by activating the pathway involving the Wiskott-Aldrich syndrome protein (WASP) and the actin-related protein complex Arp2/3. Other studies show that actin polymerizes from cholesterol-sphingolipid-rich membrane microdomains called 'rafts', in a manner dependent on tyrosine phosphorylation. Although actin has been implicated in vesicle trafficking, and rafts are sites of active phosphoinositide and tyrosine kinase signaling that mediate apically directed vesicle trafficking, it is not known whether phosphoinositide regulation of actin dynamics occurs in rafts, or if it is linked to vesicle movements. RESULTS: Overexpression of type I phosphatidylinositol phosphate 5-kinase (PIP5KI), which synthesizes PIP(2), promoted actin polymerization from membrane-bound vesicles to form motile actin comets. Pervanadate (PV), a tyrosine phosphatase inhibitor, induced comets even in the absence of PIP5KI overexpression. PV increased PIP(2) levels, suggesting that it induces comets by changing PIP(2) homeostasis and by increasing tyrosine phosphorylation. Platelet-derived growth factor (PDGF) enhanced PV-induced comet formation, and these stimuli together potentiated the PIP5KI effect. The vesicles at the heads of comets were enriched in PIP5KIs and tyrosine phosphoproteins. WASP-Arp2/3 involvement was established using dominant-negative WASP constructs. Endocytic and exocytic markers identified vesicles enriched in lipid rafts as preferential sites of comet generation. Extraction of cholesterol with methyl-beta-cyclodextrin reduced comets, establishing that rafts promote comet formation. CONCLUSIONS: Sphingolipid-cholesterol rafts are preferred platforms for membrane-linked actin polymerization. This is mediated by in situ PIP(2) synthesis and tyrosine kinase signaling through the WASP-Arp2/3 pathway. Actin comets may provide a novel mechanism for raft-dependent vesicle transport and apical membrane trafficking.

Effect of Brahman genetics on myofibrillar protein degradation, collagen crosslinking, and tenderness of the longissimus lumborum.

The objective of this study was to examine the effect of percent Brahman genetics on Warner-Bratzler shear force (WBSF), desmin and troponin-T (TnT) degradation, hydroxylysyl pyridinoline (HP) crosslink content, and perimysial collagen melting temperature. Steers ( = 131) produced in 2012 and 2013 were harvested at 1.27 cm of visual s.c. back fat thickness. Steers were divided into 4 genetic categories consisting of steers that contained 6/32 or less Brahman genetics, 12/32 Brahman genetics, 14/32 to 18/32 Brahman genetics, and 23/32 to 32/32 Brahman genetics. Twenty-four hours after harvest, a 7.62-cm piece of the longissimus lumborum beginning at the 13th rib was collected and aged for 14 d. Following aging, three 2.54-cm steaks were cut for WBSF, trained sensory panel, and laboratory analyses. Laboratory analyses steaks were used to determine protein degradation, HP crosslink analysis, and perimysial collagen melting temperature. Data were analyzed using a polynomial regression for unequally spaced treatments. As the percent Brahman genetics increased, WBSF increased (linear, = 0.01). As percent Brahman genetics increased, tenderness score decreased (less tender) and connective tissue score increased (more connective tissue; linear, = 0.01). As the percentage of Brahman genetics increased, the amount of degraded desmin (38 kDa) and TnT (34 and 30 kDa) decreased (linear, < 0.03) whereas the amount of immunoreactive 36 kDa TnT increased (linear, = 0.04). Percent Brahman genetics had no effect ( = 0.14) on HP crosslink content but did tend to increase ( = 0.07) perimysial collagen melting temperature as the percent Brahman increased. The percentage of Brahman genetic influence was positively correlated to WBSF ( = 0.25), 36 kDa immunoreactive TnT ( = 0.26), and perimysial collagen melting temperature ( = 0.25, = 0.01). Sensory panel tenderness ( = -0.44), juiciness ( = -0.26), and connective tissue scores ( = -0.63); 38 kDa degraded desmin ( = -0.34), 34 ( = -0.36) and 30 kDa degraded TnT ( = -0.29); and HP collagen crosslinks ( = -0.20) were negatively correlated to percent Brahman genetic influence ( < 0.03). Increasing Brahman genetic influence in steers negatively affects tenderness, partially through a reduction in degradation of desmin and TnT. Although HP collagen crosslinks are unaffected by Brahman genetics, a tendency for increased perimysium melting temperature indicates that other collagen-stabilizing crosslinks may be affected.

Effects of anabolic implants and ractopamine-HCl on muscle fiber morphometrics, collagen solubility, and tenderness of beef longissimus lumborum steaks.

The objective of this study was to examine the effects of growth-promoting technologies (GP) and postmortem aging on longissimus lumborum muscle fiber cross-sectional area (CSA), collagen solubility, and their relationship to meat tenderness. Two groups of black-hided crossbred feedlot heifers (group 1: = 33, initial BW 430 ± 7 kg; group 2: = 32, initial BW 466 ± 7 kg) were blocked by BW and assigned to 1 of 3 treatments consisting of: no implant and no ractopamine hydrochloride (CON; = 21); implant, no ractopamine hydrochloride (IMP; = 22); implant and ractopamine hydrochloride (COMBO; = 22). Heifers that received an implant were administered an implant containing 200 mg trenbolone acetate and 20 mg estradiol on d 0 of the study, and heifers in the COMBO group received 400 mg∙head∙d of ractopamine hydrochloride for 28 (Group 1) or 29 d (Group 2) at the end of 90- (Group 1) or 106-d (Group 2) feeding period. Following harvest, strip loins were collected and further fabricated into 5 roasts for postmortem aging (DOA) periods of 2, 7, 14, 21, or 35 d. After aging, Warner-Bratzler shear force (WBSF), muscle fiber CSA, and collagen solubility were measured. There was no treatment × DOA interaction for WBSF ( = 0.86), but treatment and DOA impacted WBSF ( < 0.01). Over the entire aging study, COMBO steaks had greater ( < 0.01) shear force values when compared to CON steaks. The IMP steaks tended to have decreased ( = 0.07) shear force when compared to the COMBO steaks, but did not differ ( = 0.11) from CON steaks. The IMP and COMBO treatments had increased type IIA fiber CSA when compared to CON ( < 0.01). When compared to each other, the IMP and COMBO type IIA fiber CSA did not differ ( = 0.76). Type I and IIX fiber CSA tended to be greater than CON for IMP and COMBO treatments ( < 0.10). There was no treatment × DOA interaction for all collagen measures ( > 0.33). Collagen amounts were not impacted by GP treatment ( > 0.72), but DOA increased the concentration of soluble collagen ( = 0.04). Fiber CSA of all fiber types were positively correlated ( < 0.05; = 0.21 to 0.28) with WBSF only on d 2 of aging, while soluble collagen amount tended to negatively correlate with WBSF on d 7 and 14 of aging ( < 0.10; = -0.24 and -0.23, respectively). Administration of GP during heifer finishing resulted in greater steak WBSF over 35 d of aging, which was not due to collagen characteristics and only minimally affected by fiber CSA.

Feeding microalgae meal (All-G Rich; CCAP 4087/2) to beef heifers. I: Effects on longissimus lumborum steak color and palatibility.

The objective of this study was to examine effects of 4 levels of microalgae meal (All-G Rich, CCAP 4087/2; Alltech Inc., Nicholasville, KY) supplementation to the diet of finishing heifers on longissimus lumborum (LL) steak PUFA content, beef palatability, and color stability. Crossbred heifers ( = 288; 452 ± 23 kg initial BW) were allocated to pens (36 pens and 8 heifers/pen), stratified by initial pen BW (3,612 ± 177 kg), and randomly assigned within strata to 1 of 4 treatments: 0, 50, 100, and 150 g·heifer·d of microalgae meal. After 89 d of feeding, cattle were harvested and LL were collected for determination of fatty acid composition and Warner-Bratzler shear force (WBSF), trained sensory panel evaluation, and 7-d retail color stability and lipid oxidation analyses. Feeding microalgae meal to heifers increased (quadratic, < 0.01) the content of 22:6-3 and increased (linear, < 0.01) the content of 20:5-3. Feeding increasing levels of microalgae meal did not impact total SFA or MUFA ( > 0.25) but tended ( = 0.10) to increase total PUFA in a quadratic manner ( = 0.03). Total omega-6 PUFA decreased (linear, = 0.01) and total omega-3 PUFA increased (quadratic, < 0.01) as microalgae meal level increased in the diet, which caused a decrease (quadratic, < 0.01) in the omega-6:omega-3 fatty acid ratio. Feeding microalgae meal did not affect WBSF values or sensory panel evaluation of tenderness, juiciness, or beef flavor scores ( > 0.16); however, off-flavor intensity increased with increasing concentration of microalgae meal in the diet (quadratic, < 0.01). From d 5 through 7 of retail display, steaks from heifers fed microalgae meal had a reduced a* value and oxymyoglobin surface percentage, with simultaneous increased surface metmyoglobin formation (quadratic, < 0.01). Lipid oxidation analysis indicated that at d 0 and 7 of display, as the concentration of microalgae meal increased in the diet, the level of oxidation increased (quadratic, < 0.01). Muscle fiber type percentage or size was not influenced by the inclusion of microalgae meal in diets ( > 0.19); therefore, the negative effects of microalgae on color stability were not due to fiber metabolism differences. Feeding microalgae meal to finishing heifers improves PUFA content of beef within the LL, but there are adverse effects on flavor and color stability.

Feeding microalgae meal (All-G Rich; CCAP 4067/2) to beef heifers. II: Effects on ground beef color and palatability.

The objective of this study was to examine the effects of feeding microalgae meal (All-G Rich, CCAP 4087/2; Alltech Inc., Nicholasville, KY) to finishing heifers on 85% lean and 15% fat (85/15) ground beef PUFA content, palatability, and color stability. Crossbred heifers ( = 288; 452 ± 23 kg initial BW) were allocated to pens (36 pens and 8 heifers/pen), stratified by initial pen BW (3,612 ± 177 kg), and randomly assigned within strata to 1 of 4 treatments: 0, 50, 100, and 150 g·heifer·d of microalgae meal. After 89 d of feeding, a subset of heifers (3/pen) was harvested and the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius were collected for processing into ground beef. At 42 d postmortem, 85/15 ground beef was formulated and formed into 112-g patties and fatty acid composition, subjective palatability, and 96-h retail color stability analyses were conducted. Increasing dietary microalgae meal concentration increased ground beef 20:5-3 and 22:6-3 fatty acids (quadratic, < 0.01). There was a treatment × hour interaction for all color attributes ( < 0.01). On d 0, microalgae tended ( = 0.08) to decrease L*, but patties had similar L* values the remainder of display ( > 0.12). Feeding microalgae meal affected ( = 0.02) b* at 24 h and decreased (linear, = 0.08) b* at 48 h. From h 0 to 36 of display, microalgae affected redness of patties ( < 0.02), and from 48 to 72 h, microalgae meal decreased a* value (linear, < 0.04). Microalgae meal did not impact sensory panel firmness, overall tenderness, or juiciness scores ( > 0.20) but tended to affect ( = 0.10) cohesiveness scores. As the amount of microalgae meal fed to heifers increased, beef flavor intensity decreased (linear, < 0.01) and off-flavor intensity increased (quadratic, < 0.05). Surface oxymyoglobin and metmyoglobin were impacted by microalgae meal from 12 to 36 h of display ( < 0.01). From 48 to 84 h of display, feeding microalgae meal to heifers decreased (linear, < 0.09) surface oxymyoglobin and increased (linear, < 0.02) surface metmyoglobin of patties. Although feeding microalgae meal to heifers increases the PUFA content of 85/15 ground beef, there are undesirable effects on flavor and color stability.

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.

Effect of extended postmortem aging and steak location on myofibrillar protein degradation and Warner-Bratzler shear force of beef M. semitendinosus steaks.

The objective of this study was to evaluate the effect of steak location and postmortem aging on cooked meat tenderness and myofibrillar protein degradation of steaks from M. semitendinosus (ST). Following harvest and a 6 d chill period, the left ST was removed from carcasses of crossbred feedlot steers ( = 60, average hot carcass weight 427 ± 24 kg). Each ST was fabricated into ten 2.54-cm thick steaks originating from the proximal to distal end of the muscle. Steaks cut adjacent to each other were paired, vacuum packaged, and randomly assigned to 7, 14, 21, 42, or 70 d of aging at 2 ± 1°C. After aging, within each steak pair, steaks were randomly assigned to Warner-Bratzler shear force or myofibrillar proteolysis analysis (calpain activity and desmin and troponin-T degradation). Muscle fiber type and size were also determined at the 2 ends of the muscle. There was no location × d of aging interaction ( = 0.25) for ST steak WBSF. Steak location affected (quadratic, < 0.01) WBSF. As steaks were fabricated from the proximal to distal end, WBSF values decreased toward the middle of the muscle and then increased toward the distal end. Activity of all calpains and myofibrillar protein proteolysis were unaffected by steak location ( > 0.13). Type I, IIA, and IIX muscle fibers were larger at the proximal end of the muscle than the distal end ( < 0.01). Increasing d of aging improved WBSF (quadratic, < 0.01) for the duration of the 70 d postmortem period. As d of aging increased, intact calpain-1 activity decreased (quadratic, < 0.01) with activity detected through 42 d. Day of aging affected autolyzed calpain-1 (linear, < 0.01) and calpain-2 activity (quadratic, < 0.01). Through d 70 of aging, the intensity of intact 55 kDa desmin band decreased (linear, < 0.01), while there was an increase (linear, < 0.01) in the degraded 38 kDa band. Similarly, d of aging increased troponin-T proteolysis, indicated by a decrease (quadratic, < 0.01) in intensity of the intact 40 kDa band and an increase (linear, < 0.01) in the 30 kDa degraded band. Intramuscular WBSF differences are not due to proteolytic activity or myofibrillar degradation and seem related to muscle fiber size. The improvement of ST steak WBSF through 70 d of aging is partly due to continued degradation of desmin and troponin-T. Calpain proteolytic analysis indicates that autolyzed calpain-1 and calpain-2 may be involved in extended postmortem myofibrillar protein proteolysis.

Use of electromyography to detect muscle exhaustion in finishing barrows fed ractopamine HCl.

The objectives of this study were to determine the effects of dietary ractopamine HCl (RAC) on muscle fiber characteristics and electromyography (EMG) measures of finishing barrow exhaustion when barrows were subjected to increased levels of activity. Barrows ( = 34; 92 ± 2 kg initial BW) were assigned to 1 of 2 treatments: a conventional swine finishing diet containing 0 mg/kg ractopamine HCl (CON) or a diet formulated to meet the requirements of finishing barrows fed 10 mg/kg RAC (RAC+). After 32 d on feed, barrows were individually moved around a track at 0.79 m/s until subjectively exhausted. Wireless EMG sensors were affixed to the deltoideus (DT), triceps brachii lateral head (TLH), tensor fasciae latae (TFL), and semitendinosus (ST) muscles to measure median power frequency (MdPF) and root mean square (RMS) as indicators of action potential conduction velocity and muscle fiber recruitment, respectively. After harvest, samples of each muscle were collected for fiber type, succinate dehydrogenase (SDH), and capillary density analysis. Speed was not different ( = 0.82) between treatments, but RAC+ barrows reached subjective exhaustion earlier and covered less distance than CON barrows ( < 0.01). There were no treatment × muscle interactions or treatment effects for end-point MdPF values ( > 0.29). There was a treatment × muscle interaction ( = 0.04) for end-point RMS values. The RAC diet did not change end-point RMS values in the DT or TLH ( > 0.37); however, the diet tended to decrease and increase end-point RMS in the ST and TFL, respectively ( < 0.07). There were no treatment × muscle interactions for fiber type, SDH, or capillary density measures ( > 0.10). Muscles of RAC+ barrows tended to have less type I fibers and more capillaries per fiber ( < 0.07). Type I and IIA fibers of RAC+ barrows were larger ( < 0.07). Compared with all other muscles, the ST had more ( < 0.01) type IIB fibers and larger type I, IIA, and IIX fibers ( < 0.01). Type I, IIA, and IIX fibers of the ST also contained less SDH compared with the other muscles ( < 0.01). Barrows fed a RAC diet had increased time to subjective exhaustion due to loss of active muscle fibers in the ST, possibly due to fibers being larger and less oxidative in metabolism. Size increases in type I and IIA fibers with no change in oxidative capacity could also contribute to early exhaustion of RAC+ barrows. Overall, EMG technology can measure real-time muscle fiber loss to help explain subjective exhaustion in barrows.

Cytoarchitecture and physical properties of cytoplasm: volume, viscosity, diffusion, intracellular surface area.

Classical biochemistry is founded on several assumptions valid in dilute aqueous solutions that are often extended without question to the interior milieu of intact cells. In the first section of this chapter, we present these assumptions and briefly examine the ways in which the cell interior may depart from the conditions of an ideal solution. In the second section, we summarize experimental evidence regarding the physical properties of the cell cytoplasm and their effect on the diffusion and binding of macromolecules and vesicles. While many details remain to be worked out, it is clear that the aqueous phase of the cytoplasm is crowded rather than dilute, and that the diffusion and partitioning of macromolecules and vesicles in cytoplasm is highly restricted by steric hindrance as well as by unexpected binding interactions. Furthermore, the enzymes of several metabolic pathways are now known to be organized into structural and functional units with specific localizations in the solid phase, and as much as half the cellular protein content may also be in the solid phase.

The relationship between pre-harvest stress and the carcass characteristics of beef heifers that qualified for kosher designation.

Differences in pre-harvest stress measurements and carcass characteristics between kosher and not-qualified-as-kosher cattle were evaluated. Finished heifers (n=157) were slaughtered by a shochet while held in an upright position using Glatt slaughter procedures. Stress measurements were collected prior to slaughter. Carcass data were collected, and 3.8-cm thick samples were taken from the loin at the 13th rib. Steaks from each sample were evaluated for mechanical tenderness and simulated retail display. Cattle with shorter times from gate to exsanguination and lower vocalization scores were more likely (P < 0.01) to qualify as kosher. Kosher carcasses had larger (P = 0.02) ribeye areas and higher (P < 0.0001) Warner-Bratzler shear values. At each day of simulated retail display, kosher steaks had lower (P < 0.05) L*, a*, and b* values. These data suggest that body composition and pre-harvest stress affect the likelihood of a beef animal qualifying as kosher and quality differences exist between kosher and non-kosher steaks.