Muscle Width Research Articles

Effect of a moderate feed restriction on subsequent growth and body composition in pigs raised under high environmental temperatures

The experiment was conducted to assess the influence of a moderate feed restriction during the growth period on overall performance, corporal traits and fatty acid composition in pig backfat in pigs raised under high environmetal temperatures. A hundred Large White x (Large White x Landrace) barrows with an average initial weight of 34.5 kg were randomly distributed, in pens (10 pigs per pen). Fifty pigs were fed ad libitum for 36 days (AL pigs) and another fifty were restricted by 25% of their ad libitum consumption during the same period (R pigs). During the subsequent re-feeding period (64 days) all pigs were fed ad libitum. The only diet used contained 13.4 MJ ME kg -1 , 17% crude protein and 1.3% lysine. The minimum, maximum and mean average temperatures recorded during the feed restriction and post-restriction periods were, oC: 21.5 ± 1.2, 28.6 ± 1.3 and 25.0 ± 1.1, and 22.6 ± 0.9, 31.2 ± 1.0 and 26.9 ± 0.9, respectively. Considering the whole study period, the average daily gain and average daily feed intake were higher (P 0.05) (2.95 vs 2.95 kg . kg -1 ). At the end of experiment, no differences for dorsal fat thickness and area and for longissimus dorsi muscle depth, width and area, measured at site of the last rib by means of a real-time ultrasound device, were found between experimental groups. The linolenic acid proportions of the subcutaneous fat outer and inner layer were higher in AL than in R pigs (P<0.05), while palmitic and saturated fatty acids total proportions of the subcutaneous fat inner layer were higher in R than in AL pigs (P<0.05).

Genetic correlations among indicator traits for carcass composition measured in yearling beef bulls and finished feedlot steers

Genetic correlations were examined among 10 live growth and ultrasound traits measured in yearling beef bulls (n = 2172) and four carcass traits measured in crossbred finished feedlot steers (n = 1031). Heritabilities ranged from 0.13 (bull ultrasound longissimus muscle width) to 0.83 (yearling bull hip height). Genetic correlations indicated that selecting yearling bulls for increased growth rate and hip height would lead to higher carcass weight, increased longissimus muscle area and reduced levels of carcass marbling in steers. Bull ultrasound fat depth was positively associated with both carcass fat depth and marbling score. Most ultrasound longissimus muscle size measurements in bulls were positively associated with each other and with carcass longissimus muscle area in steers, but the magnitude of the genetic correlation with carcass measurements depended on the bull longissimus muscle size trait in question. This suggests that longissimus muscle shape in bulls may be related to carcass weight, fat and muscle traits in steers. Results confirm that while ultrasound is a valuable tool for the genetic improvement of carcass traits in beef cattle, genetic correlations between live bull ultrasound and steer carcass traits less then unity suggest that selection would benefit from multiple trait evaluations in situations where reliable carcass data are available. Key words: Ultrasound, beef carcass, heritability, genetic correlation

Volume changes of supraspinatus and infraspinatus muscles after supraspinatus tendon repair: A magnetic resonance imaging study

Muscle volume was measured, by use of magnetic resonance imaging (MRI), as a direct indicator of functional recovery of the supraspinatus and infraspinatus muscles after supraspinatus tendon repair, because atrophy of the supraspinatus and infraspinatus muscles was observed in all patients with a torn supraspinatus tendon. Seventy-three patients who had a cuff tear limited only to the supraspinatus tendon were included in this study. The University of California, Los Angeles score improved significantly after surgery. MRI was carried out before surgery and 6, 12, and 24 months postoperatively in all patients. Muscle volume of the supraspinatus was assessed on images of the oblique coronal plane, and that of the infraspinatus was assessed on images of the axial plane. The width of the supraspinatus muscle did not recover until 6 months postoperatively. Direct measurement of the infraspinatus muscle volume by use of MRI can be a good indicator when evaluating whether the repaired rotator cuffs are actually functioning.

NS-398, a Cyclooxygenase-2-Specific Inhibitor, Delays Skeletal Muscle Healing by Decreasing Regeneration and Promoting Fibrosis

Nonsteroidal anti-inflammatory drugs are often prescribed after muscle injury. However, the effect of nonsteroidal anti-inflammatory drugs on muscle healing remains primarily controversial. To further examine the validity of using these drugs after muscle injury, we investigated the working mechanism of NS-398, a cyclooxygenase-2-specific inhibitor. In vitro experiments showed that NS-398 inhibited the proliferation and maturation of differentiated myogenic precursor cells, suggesting a detrimental effect on skeletal muscle healing. Using a mouse laceration model, we analyzed the in vivo effect of NS-398 on skeletal muscle healing at time points up to 4 weeks after injury. The in vivo results revealed delayed muscle regeneration at early time points after injury in the NS-398-treated mice. Compared to controls, lacerated muscles treated with NS-398 expressed higher levels of transforming growth factor-beta1, which corresponded with increased fibrosis. In addition, transforming growth factor-beta1 co-localized with myostatin, a negative regulator of skeletal muscle growth. We also found reduced neutrophil and macrophage infiltration in treated muscles, indicating that the delayed skeletal muscle healing observed after NS-398 treatment could be influenced by the anti-inflammatory effect of NS-398. Our findings suggest that the use of cyclooxygenase-2-specific inhibitors to treat skeletal muscle injuries warrants caution because they may interfere with muscle healing.

Functional Ischemic Mitral Regurgitation in Anterior Ventricular Remodeling: Results of Surgical Ventricular Restoration with and Without Mitral Repair

Ischemic functional mitral regurgitation following ischemic cardiomyopathy is a secondary phenomenon to ventricular dilation, and therapeutic approaches to this complication are not uniform. Solutions to improve mitral function include either mitral repair or observing the effects of coronary revascularization and/or ventricular rebuilding during surgical ventricular restoration (SVR). The present study of 108 patients (comprising 18% of our 588 SVR population) reports the effects of mitral repair following SVR and CABG by comparing geometric, functional, hemodynamic and outcome changes to SVR patients without mitral repair. The degree of mitral regurgitation went from 2.9 +/- 1.2 before to 0.7 +/- 0.7 after SVR and mitral repair. SVR improved EF from 29 +/- 7% to 34 +/- 10% p 0.001; reduced end diastolic volume from 243 +/- 74 to 163 +/- 53 ml and end systolic volume from 170 +/- 63 to 107 +/- 41 ml, p 0.000. Ventricular size and shape geometric measurements improved in all patients, either with and without mitral repair. SVR improved tenting and papillary muscle width between muscle heads in all patients, but alterations in mitral annular size improved only following mitral repair. Preoperative mitral regurgitation occurred in patients with larger ventricular volume and lower ejection fraction and was an independent predictor of operative mortality risk.

Effects of unilateral lateral rectus recession according to the tendon width in intermittent exotropia

To verify the effect of unilateral lateral rectus recession for each millimeter according to the tendon width in intermittent exotropia. A total of 37 patients (37 eyes) of 7 to 11 years of age with basic-type intermittent exotropia and a deviation of 16-25 Prism Diopters (PD) were included in this study. Under general anaesthesia, the tendon width of the lateral rectus of the deviating eye near insertion was measured with calipers, prior to dissection of the muscle tendon from the sclera. Patients underwent 6.5-10 mm unilateral lateral rectus recession. The effect of lateral recession for each millimeter was the absolute value of the angle of preoperative deviation plus postoperative deviation on the second day divided by the total amount of recession. Mean tendon width of the lateral rectus of a deviating eye was 8.3 mm (range: 6.5-9.5). The mean effect per millimeter of unilateral rectus recession in those 37 patient was 2.98+/-0.42 PD (range: 2.4-4.1). The effect of recession was larger in cases in which the tendon width of the lateral rectus was narrower (P=0.000, r=0.72). The tendon width of the lateral rectus muscle can be a useful indicator to estimate the effect of lateral rectus recession in intermittent exotropia.

Computed tomographic features of bilateral coronoid process hyperplasia with special emphasis on patients without interference between the process and the zygomatic bone

Objective To reveal computed tomography (CT) features of patients with coronoid process hyperplasia without interference between the process and the zygomatic bone. Study design A case-control study was designed. Thirteen cases without interference (2 male and 11 female, 28-56 years old) and 65 controls were sampled from a patient database. Differences in CT features were analyzed between the 2 groups regarding the following 7 points of 5 regions: configuration of the coronoid process, vertical level of the coronoid process, the distance between the bilateral zygomatic arches, thickness of the temporal muscle, anteroposterior width of the temporal muscle, thickness of the temporal muscle tendon, and thickness of the masseter muscle. Cluster analysis was applied to differentiate between individuals. Results All cases had bilateral hyperplastic change of the coronoid process. Differences were found between the cases and controls in 6 of 7 CT features with the exception of temporal muscle thickness. All incidences of significant difference showed larger values in the cases. All cases were clustered into the same group and were differentiated from the controls. Conclusion CT features appeared to be effective for diagnosis of this condition, and these patients should be put into the same category under the diagnosis of coronoid process hyperplasia.

Characterization of the uterine phenotype of non-classical ERα (estrogen receptor α) signaling in vivo.

Determine the non-ERE (estrogen response element) dependent actions of ERα on growth, differentiation, and developmental gene expression in the female reproductive tract. Experimental laboratory study. Morphometric analysis, immunohistochemistry, and quantitative real-time PCR. Previous work from our laboratory demonstrated that the mutation of residues 207 and 208 of ERα (within the proximal P-box of the first zinc finger of the DNA binding domain) to alanines abolished classical ERα signaling via ERE. We generated a knock-in/knockout mouse (E207A/G208A, ERAA/-) lacking classical ERα signaling by crossbreeding ERAA/WTto estrogen receptor-α knockout (αERKO) animals. The ERAA/- animals signal via the non-classical ERα pathway. The non-classical pathway involves a ligand bound ERα that interacts with transcription factors such as AP1 and Sp1. Animals were sacrificed at 8 weeks of age. The presence of a single ERAA/- allele (n = 8) supported significant uterine growth compared with αERKO animals (n = 6). The uterine radius of ERAA/-animals was larger than age matched αERKO mice (321 μm ± 58 vs. 170 ± 62, p < .01). The width of the inner circular muscle (ICM) layer of ERAA/- mice was also increased (54 μm ± 34 vs. 38 ± 15, p < .05). The ERAA/-uterus also exhibited altered glandular development. The endometrial glands were more numerous but remained organized in clusters in the stroma. The mesenchymal differentiation characteristic of wild-type (WT) mice was restored with positive ICM coexpression for vimentin and α-actin in all ERAA/-animals. In contrast, the αERKO uterus lacked cytodifferentiation with no positive staining of the ICM for vimentin or α-actin. The expression of the Wnt genes (Wnt-7a, Wnt-5a, and Wnt-4a) and EGFR (epidermal growth factor receptor) did not differ between ERAA/-(n = 8) and αERKO (n = 7). However, the uterine expression of cyclin D2 (which lacks an ERE) increased 2.6-fold in ERAA/- compared to αERKO. The expression of PR (progesterone receptor isoform A and B) was down-regulated significantly in ERAA/- compared to αERKO (-2.5-fold, p < .05). Non-classical ERα signaling via the presence of a single ERAA/-allele is sufficient to restore many features of growth and differentiation of the murine uterus. In addition, glandulargenesis progresses beyond that observed in the αERKO uterus suggesting that non-classical signaling is involved in the epithelial-mesenchyme interactions required for complex gland formation. Developmental gene expression is not altered by the restoration of non-classical ERα signaling. The up-regulation of cyclin D2 and the loss of progesterone receptor expression provide a potential mechanism for the observed phenotype.

Extraocular muscle enlargement with tendon involvement in thyroid-associated orbitopathy

PurposeTo evaluate the configuration of extraocular muscle and tendon enlargement in patients with thyroid-associated orbitopathy (TAO). DesignRetrospective, noncomparative case series. MethodsWe retrospectively evaluated the preoperative computed tomography (CT) or magnetic resonance imaging (MRI) scans, or both, of 125 consecutive patients with previously diagnosed TAO. Axial CT (n = 88) or MRI (n = 37) slices of the orbits were examined for tendon involvement of enlarged medial or lateral recti muscles. A ratio of tendon to muscle width greater than 0.5 was considered as tendon involvement. ResultsEight patients (6.4%) with TAO demonstrated tendon involvement on axial CT or MRI. These patients had significantly greater diplopia in primary gaze than patients with no tendon involvement or patients with no muscle enlargement. ConclusionThe configuration of extraocular muscle enlargement on imaging studies has traditionally been used to differentiate TAO from other inflammatory processes because the tendon is typically spared (fusiform configuration) in TAO. However, we found that the configuration of tendon involvement (cylindrical configuration) can occasionally be noted in TAO and may be more frequently associated with primary gaze diplopia. Tendon involvement does not eliminate the diagnostic possibility of TAO.

A histological study of the hph-1 mouse mutant: an animal model of phenylketonuria and infantile hypertrophic pyloric stenosis.

To quantify the chronological sequence of changes in the morphology and immunoreactivity for neurotransmitters in the pylorus of an animal model of infantile hypertrophic pyloric stenosis and phenylketonuria. Thirty specimens of pylorus from hph-1 mice and age/sex matched controls (age range: 10-180 days) were examined using conventional histology and immunohistochemistry for a variety of antigens: protein gene product 9.5, a pan neuronal marker; vasoactive intestinal polypeptide; nitric oxide synthase two antigens coalesced to the same inhibitory neurons in humans; substance P, a potent excitatory neurotransmitter; and calcitonin gene related peptide, a neurotransmitter implicated in the somatic afferent innervation of the stomach. The changes in the morphology of the muscle layers were quantified and statistically analysed for each age group (10, 20, 40, 90 and 180 days). Between 10 and 90 days of age, all muscle layers of the hph-1 mice were hypertrophied, for example, 10 days, hph-1 longitudinal muscle mean diameter = 3.4, control = 1.8; hph-1 circular muscle width = 11.5, control = 4.7. The hph-1 mice were significantly smaller during this period (40 days, hph-1 weight = 10 g, control = 25 g). There was no change in the pattern of expression of the antigens examined within the hph-1 mice compared with the controls. Hph-1 mice develop a transient smooth muscle hypertrophy of the pylorus attended by gastric distension and failure to gain weight. These changes resolve as the pyloric muscle hypertrophy resolves.

Genetic analysis of live weight and ultrasonic fat and muscle traits in a hill sheep flock undergoing breed improvement utilizing an embryo transfer programme

AbstractGenetic parameters for pre-weaning live weights and ultrasonic scanning measurements were estimated from a flock of Scottish Blackface sheep undergoing an embryo transfer programme. Maternal environmental effects could be evaluated without confounding with maternal genetic effects because embryos were transferred to unrelated recipient ewes. The data for the study were collected over a 7-year period (1993-1999) and related to a conventional hill farming system. The data were from 1465 lambs, the progeny of 60 sires, 263 donors and 784 recipient ewes. The only exception to the conventional farming system was at mating time when embryos were collected from selected donor ewes, following superovulation, and transferred to unrelated recipient ewes. Maternal environmental effects were important for birth weight (BW), 4-week weight (W4) and weaning weight (WW) but of less importance for ultrasonic fat depth (UFD), muscle depth (UMD) and muscle width (UMW). The heritabilities of the pre-weaning weights were moderate (0·17 to 0·23). The heritabilities of UFD and UMD were 0·44 and 0·27 respectively and were higher than found in previous similar studies. The heritability of UMW was low, 0·06. The genetic and phenotypic correlations among the pre-weaning weight traits were positive and moderate. There was a positive genetic ( + 0·25) and phenotypic ( + 0·24) correlation between UFD and UMD. The phenotypic and genetic correlations between BW and W4 and the scanning traits (UFD, UMD and UMW) were close to zero, and the correlations of WW with UFD, UMD and UMW were positive. The results of this study clearly demonstrate the importance of maternal environmental effects for lamb weights up to weaning and also suggest that genetic improvement for carcass composition in some populations of extensively reared hill sheep could be achieved more rapidly than previously thought possible.

Genetic parameters for meat quality and carcass traits and their correlation with wool traits in Australian Merino sheep

Estimates of genetic parameters for carcass traits in Merino sheep are presented, including muscle pH and colour, which are indicators of meat quality. The inclusion of these in the parameter set for genetic evaluation will provide the basis for more accurate estimated breeding values and the design of better breeding programs for improving meat traits in straightbred Merino sheep and crossbred lamb production. Data from 1045, nineteen-month-old Merino rams, the progeny of 125 sires from 3 strains that are representative of the industry, were used. Heritability and genetic correlations were estimated by fitting an animal model using a REML procedure in univariate and multivariate analyses. The traits included fasted pre-slaughter liveweight; dressing %; carcass tissue depth at the GR site (FATGR); fat depth at the C site (FATC); eye muscle depth (EMD), width (EMW), and area (EMA); ultimate pH and colour (L*, a*, b*) of the eye muscle. Multivariate analyses were used to estimate genetic correlations among meat traits and between wool traits (clean wool weight and mean fibre diameter) and selected carcass and meat traits. Estimates of heritability were: liveweight 0.51 (±0.10), dressing % 0.39 (±0.10), FATGR 0.33 (±0.09), FATC 0.20 (±0.08), EMD 0.27 (±0.08), EMW 0.15 (±0.07), EMA 0.23 (±0.08), muscle pH 0.27 (±0.09), and 0.14 (±0.07), 0.02 (±0.06), and 0.04 (±0.06) for the meat colour measurements L*, a*, and b* respectively. There was a favourable genetic correlation between muscle pH and colour L* of –0.56 (±0.23). There were also significant genetic correlations between wool weight and FATGR (–0.34 ± 0.16) and between mean fibre diameter and muscle colour L* (–0.66 ± 0.27). The study indicates that there is genetic variation for carcass traits, including indicators of meat quality, with scope for selection to improve meat production and quality in Merino sheep.

Variability in Sonic Muscle Size and Innervation among Three Sciaenids: Spot, Atlantic Croaker, and Weakfish

Comparisons of sonic muscle width, body cavity length, and sonic muscle innervation patterns were made for three species of sciaenids: weakfish, Cynoscion regalis; Atlantic croaker, Micropogonias undulatus; and spot, Leiostomus xanthurus. Body cavity length and sonic muscle width (rostrocaudal extent), both normalized for TL, were significantly different among the three species, increasing from spot to croaker to weakfish. However, the percentage of the body cavity length including sonic muscle was greater in the croaker and weakfish than in the spot. The sonic muscles of sciaenids are innervated by a number of true spinal nerves rather than by paired occipital spinal nerves. The number of sonic nerves increased from spot (4–5 nerves from vertebrae 4–9) to croaker (6–8 from vertebrae 3–10) to weakfish (8–9 nerves from vertebrae 3–12), paralleling the increase in muscle width. Although the number of nerves and their vertebra of origin varied within each species, they were bilaterally symmetrical within an individual. The spinal nerves emerged from two (dorsal and ventral) foramina in croaker and spot and from the sole foramen observed in weakfish vertebrae. Therefore, a longer body cavity supports a wider sonic muscle that is innervated by a greater number of spinal nerves.

Great tits (Parus major) reduce body mass in response to wing area reduction: a field experiment

Flight performance is crucial in determining whether a small bird will survive an attack by a predator. Given the importance of body mass in determining flight performance, it has been suggested that birds should strategically regulate body mass as a response to predation risk. However, all experiments up to now have been carried out with captive birds, comparing experimental to control birds. Here we present data from the first experiment in the field using a within-individuals experimental design. The wing area of wild great tits, Parus major, was reduced by reversibly taping primaries five to seven. This allowed for the same individual to alternatively act as control or experimental bird. Great tits reduced body mass (but not pectoral muscle width) during episodes of wing area reduction, lending support to the view that the reduction in body mass experienced by birds during molt is a strategy rather than the result of energetic stress. Theoretical models establishing the different trade-offs that determine optimal body mass should therefore take into account this important life-history episode.

Does dehydration affect thickness of the pyloric muscle? An experimental study

Congenital hypertrophic pyloric stenosis (CHPS) is a common condition in infancy associated with smooth muscle hypertrophy and resulting in pyloric outlet obstruction. The final diagnosis of CHPS is based on precise ultrasonographic measurements of length and width of the pyloric muscle. Based on our clinical and sonographic experience, we observed that smaller measurements of the pyloric muscle were obtained in dehydrated infants than in children examined after proper fluid restoration. The clinical importance of these observations was evident because false-negative results could be obtained. An experimental animal work followed, proving our clinical observation to be true. A significant difference of about 30% to 50% was found between measurements of the muscle thickness of the gastric and pyloric muscles in a state of water deprivation, as compared with a state of full hydration ( p < 0.05). Based on our preliminary results, we suggest that children with suspected CHPS should be well hydrated before the ultrasound (US) examination is performed, to avoid false-negative results and a consequent delay in treatment. (E-mail: rstarinsky@asaf.health.gov.il)

Magnetic resonance imaging of the levator veli palatini muscle during speech.

To obtain detailed anatomic information on the levator veli palatini (LVP) muscle from magnetic resonance imaging (MRI). Quantitative measures of the configuration of the LVP muscle at rest and during speech activities were obtained. Prospective study using MRI of adult subjects with normal velopharyngeal mechanisms to determine anatomic and physiologic parameters of the levator muscle. The levator veli palatini muscle was imaged at rest and during speech activities consisting of nasal and non-nasal sounds mixed with vowels, consonants, or both (e.g., /ansa, asna, amfa, afma/). Ten normal healthy adults (five men, five women) between 21 and 53 years of age and free of oropharyngeal abnormalities. Two-dimensional spin echo static images and dynamic fast gradient echo images of the levator muscle in both the sagittal and oblique/coronal planes. On average across female (F) and male (M) subjects: distance between LVP muscle origin points, 52.6 mm (F), 54.6 mm (M); angle of levator muscle origin at rest, 64.5 degrees (F), 60.4 degrees (M); length of the levator muscle at rest, 44.1 mm (F), 46.4 mm (M); width of levator muscle at lateral margin of velum, 5.5 mm (F), 6.6 mm (M). Both the levator muscle angle of origin and length became progressively smaller from rest, nasal consonants, low vowels, high vowels, and fricatives for both female and male subjects. Across all subjects, there was a 19% reduction in length of the LVP muscle from rest position to fricative production. MRI is an effective method of imaging and measuring the LVP muscle and related structures in living subjects. Understanding the normal tissue distribution and quantification of the LVP muscle provides important information for development of a functional biomechanical model of the velopharynx and for improved surgical treatment.

Myofilament calcium sensitivity in skinned rat cardiac trabeculae: role of interfilament spacing.

The increase in myofilament Ca(2+) responsiveness on an increase in sarcomere length (SL) is, in part, the cellular basis for Frank-Starling's law of the heart. It has been suggested that a decrease in myofilament lattice spacing (LS) in response to an increase in SL underlies this phenomenon. This hypothesis is supported by previous studies in which reduced muscle width induced by osmotic compression was associated with an increase in Ca(2+) sensitivity, mimicking those changes observed with an increase in SL. To evaluate this hypothesis, we directly measured LS by synchrotron x-ray diffraction as function of SL in skinned rat cardiac trabeculae bathed in 0% to 6% dextran solutions (MW 413 000). We found that EC(50), [Ca(2+)] at which force is half-maximal, at SL between 1.95 and 2.25 microm did not vary in proportion to LS when 3% or 6% dextran solutions were applied. We also found that moderate compression (1% dextran) of skinned trabeculae at SL=2.02 microm reduced LS (LS=42.29+/-0.14 nm) to match that of uncompressed fibers at a long SL (SL=2.19 microm; LS=42.28+/-0.15 nm). Whereas increasing SL from 2.02 to 2.19 microm significantly increased Ca(2+) sensitivity as indexed by the EC(50) parameter (2.87+/-0.11 micromol/L to 2.52+/-0.12 micromol/L), similar reduction in myofilament lattice spacing achieved by compression with 1% dextran did not alter Ca(2+) sensitivity (2.87+/-0.10 micromol/L) at the short SL. We conclude that alterations in myofilament lattice spacing may not be the mechanism that underlies the sarcomere length-induced alteration of calcium sensitivity in skinned myocardium.

Alternative Ultrasound Predictors of Beef Carcass Longissimus Muscle Area11AAFC-LRC contribution number 38701044. These data were collected with funding support from the Canadian Beef Industry Development Fund for project 95H022.

Longissimus width and depth were measured using ultrasound in steers (n = 174), bulls (n = 323), and heifers (n = 347) at yearling and prior to harvest. Yearling and preharvest muscle dimensions and carcass muscle area of bulls were largest (P<0.01). Steers had wider and deeper (P<0.01) longissimus than heifers at yearling; however, preharvest muscle width and depth and carcass muscle area were greater (P<0.01) for heifers. From yearling to harvest, muscle width of bulls and heifers increased at a similar rate, which was greater (P<0.01) than that of steers. Significant (P<0.01) differences existed for muscle depth increase from yearling to harvest, where bulls had the highest deposition rates, heifers had intermediate rates, and steers had the lowest deposition rates. Correlations of carcass muscle area with muscle depth were large and positive (0.52 to 0.81) and slightly larger than correlations with muscle width (0.51 to 0.74). Muscle depth was the best single predictor of carcass muscle area; however, two-trait prediction models including both muscle width and depth were superior to single-trait prediction models. At yearling (preharvest), predicted and carcass muscle areas differed by more than 9.68 cm2 for less than 2% (5%) of steers and heifers and less than 7% (4%) of bulls. Further, yearling and pre-harvest carcass muscle area predictions were within 4.84 cm2 of carcass measurements for approximately 54 to 65% of all animals, respectively. These results indicate that ultrasound muscle width and depth may be alternative predictors of carcass muscle area and may be useful in selection of potential replacements.

Ileal absorptive adaptation to jejunal resection and extrinsic denervation: implications for living-related small bowel transplantation

Net absorption of water, electrolytes, and simple nutrients decreases early after jejunoileal autotransplantation (extrinsic denervation) in a canine model but recovers toward normal by 8 weeks. However, the ability of the extrinsically denervated ileum to adapt after total jejunectomy, which would be relevant as a model of segmental small bowel transplantation, remains unknown. Two groups of five dogs each were studied before and 2 weeks and 12 weeks after 50% proximal enterectomy. A control group remained neurally intact, whereas the other group underwent extrinsic denervation (Ext Den) of the remaining ileum. Using a perfusion technique, net absorption of water, electrolytes, and five simple nutrients (glucose, arginine, glutamine, and oleic and taurocholic acids) was measured at the three time points. Ileal morphometry was also evaluated. All dogs developed diarrhea, which resolved by 12 weeks in all but two of the Ext Den dogs. Weight in both groups was decreased at 2 weeks ( P <0.05), returned to normal at 12 weeks in control dogs, but remained low in Ext Den dogs ( P <0.05). Maximal weight loss was greater in the Ext Den group ( P <0.05). No consistent or important differences in net absorptive fluxes of water, electrolytes, or simple nutrients were noted either within or between groups at any time point. Villous height, crypt depth, and longitudinal muscle width increased significantly at 12 weeks after jejunectomy in the Ext Den dogs, but not in the control dogs ( P <0.05). Extrinsic denervation of the ileum results in persistent weight loss after proximal 50% enterectomy. Despite diarrhea, only minor changes in electrolyte absorption occur, and ileal net absorption of simple nutrients remains unaffected. The ileum of extrinsically denervated dogs undergoes a more prominent morphometric adaptation after jejunectomy. Extrinsic denervation necessitated by small bowel transplantation, independent of immune effects, does not appear to suppress the ileal adaptive response to maintain net absorption of water, electrolytes, and simple nutrients.

Maturation-dependent neointima formation in fowl aorta

Fowl show spontaneous elevation of blood pressure (BP) and neointimal plaque formation in the abdominal aorta at young ages. Maturation/age-dependent modulation of vascular lesions and a causal relationship between elevated BP and neointima formation, however, have not been clarified. We therefore intended to characterize, first, maturation/age-dependent neointimal plaque formation and vascular lesions and, second, their relationship to BP elevation. The BP measured in conscious domestic fowl, Gallus gallus, White Leghorn breed, DeKalb strain, via an indwelling catheter inserted into the ischiadic artery, increased with maturation in males; and at plateau level, BP (mmHg) was significantly ( P<0.01) higher in males (194.0±4.6, n=11) than in females (169.3±3.1, n=10). Neointimal plaques consisting of neointimal cells and abundant extracellular matrix appeared initially in the distal segment of the abdominal aorta (lesion-prone area) of chicks as early as 6 weeks old. The area (size) of neointimal plaques right above the ischiadic bifurcation increased with maturation, whereas the plaque area became smaller with some degenerative changes in adult birds. In some birds, diffuse subendothelial hyperplasia and more extensive plaque formation at the branching points of the aorta were observed. The plaque area appears to be larger in birds, particularly in males that have higher BP ( r=0.68). The width of aortic smooth muscle (SM) layers, measured in regions with no plaque, increased with age, whereas the number of cells per unit of area decreased, suggesting that hypertrophy of vascular SM occurs in response to exposure of the vascular wall to high BP. The number of cells was significantly ( P<0.01) higher in the plaque than in underlying aortic SM layers or in layers with no plaque formation. Both neointimal plaques and underlying SM layers are immunohistochemically positive for alpha SM actin, suggesting that neointimal cells are modulated SM cells, whereas the staining with SM myosin heavy chain antibody is low in neointimal plaques. Furthermore, plasma arginine levels dropped in accordance with the time of neointimal plaque formation, whereas plasma cholesterol levels showed an age-dependent increase. The results suggest that spontaneous development of neointimal plaques may be a consequence of exposure to high BP and associated local hemodynamic changes.