Effects of posture and anatomical location on inter-recti distance measured using ultrasound imaging in parous women.

STUDY DESIGN: Cross-sectional repeated measures. OBJECTIVES: To quantify the effects of posture and measurement site on the inter-recti distance (IRD) and investigate the reliability of IRD measurement using ultrasound imaging in different postures. BACKGROUND: The linea alba connects the rectus abdominis muscles anteriorly and the width is known as the IRD. The IRD is usually measured in crook-lying and is the primary outcome measure to assess for a divarication of recti abdominis (DRA). The effects of posture and measurement site on the IRD have not been investigated. METHODS: Ultrasound imaging was used to measure IRD in 41 women ≥8 weeks postpartum. The IRD was measured at three sites (superior-umbilicus, umbilicus and inferior-umbilicus), in three postures (crook-lying, sitting and standing), and repeated one-week later. The effects of posture and site were investigated using one-way ANOVAs. Reliability was analysed using Intraclass correlation coefficients (ICCs), Bland Altman analyses, standard error of measurement and minimal detectable change. RESULTS: The IRD was wider when standing vs. lying at both the superior-umbilicus and umbilicus by 0.30 cm (95% CI 0.21 to 0.39) and 0.20 cm (0.11-0.30) respectively (p < 0.001). Measurements at the inferior-umbilicus were, on average, 1.6 and 2.1 cm narrower than superior-umbilicus and umbilicus sites, respectively (p < 0.001). There was high intra-rater reliability within-session (ICC3.3) and between-session (ICC3.1) at all sites measured. CONCLUSION: The IRD can be measured reliably at all sites and postures. The IRD is wider at superior-umbilicus and umbilicus when upright compared with lying. There is a difference in IRD between all sites measured.

Effect of human muscle-derived stem cells on cryoinjured mouse bladder contractility.

OBJECTIVE: To investigate the effect of human muscle-derived stem cells (hMDSCs) on ameliorating impaired detrusor contractility in a cryoinjured bladder murine model. METHODS: The hMDSCs were isolated and cultured by modified preplate technique, and only CD34-positive hMDSCs were extracted by Mini-MACS kits. Isolated hMDSCs were prelabeled with PKH26 and injected into the cryoinjured bladder to observe the pattern and characteristics. The nude mice were subdivided into three groups: normal group (N), cryoinjury bladder group with saline injection (C), and hMDSCs injection group after cryoinjury (M). At 2 weeks after injecting hMDSCs, we compared the contractility of bladder muscle strip stimulated by electrical field stimulation (EFS), acetylcholine (Ach.), and adenosine triphosphate (ATP), and the bladder smooth muscle tissue was examined by immunohistochemistry. RESULTS: The contractile powers of bladder muscle strip in the C group were more decreased than the N group after EFS, Ach, and ATP treatment (P < .05). The bladder contractility of the M group was more increased than in the C group (P < .05), but was lower than the N group after EFS and Ach treatment. However, there was no significant difference of contractile power between the C and M groups after ATP stimulation. In immunohistochemical staining, the thickness of the bladder smooth muscle layer in the M group was significantly increased compared with the C group, and PKH26-labeled implanted cells were positive for smooth muscle cell differentiation marker (α-SMA) in the injected region. CONCLUSION: hMDSCs injection increased cholinergic bladder contractile power but not the purinergic component of bladder contraction after cryoinjury.

Isolation of human adult stem cells from muscle biopsy for future treatment of urinary incontinence.

PURPOSE: To find a suitable and cost-effective technique for isolation and culture of muscle-derived stem cells (MDSCs) obtained from muscle biopsy in large quantities. MATERIALS AND METHODS: A small muscle biopsy was taken from 10 donor rectus muscles in patients undergoing open abdominal surgery for any reason and transported on ice to the laboratory. The isolation of MDSCs was performed by two techniques; preplate and tissue explants. Initially, the isolation was carried out by preplating technique. However, enzymatic digestion of muscle biopsy in preplate technique compromised the integrity of important surface antigens of resident muscle stem cells and led to dysfunctional sorted cells. Also, many of the cells were lost in this technique and low numbers of MDSCs were yielded upon processing. Thus, we changed condition of centrifuge, but it did not affect cell numbers and their integrities. To overcome these problems, the technique was changed to tissue explants technique. RESULTS: During the first 4 days in explant medium culture, activated satellite cells detached, migrated, and slowly divided. The MDSCs proliferated around the native myofiber and after 2 to 3 weeks, individual muscle cells appeared elongated and fused to create large multinucleated myotubes. On immunofluorescent staining, these emerged cells were positive for desmin and Pax7 and flow cytometry analysis revealed that these cells were CD45-, CD56+, and variable in CD34. CONCLUSION: We concluded that tissue explant method is a suitable and costeffective technique for isolation and culture of MDSCs from muscle biopsy in large quantities.

The effect of chronically increased intra-abdominal pressure on rectus abdominis muscle histology an experimental study on rabbits.

BACKGROUND: The aim of this study was to specify the histologic response of the rectus abdominis muscle of the rabbit, to the chronically increased intra-abdominal pressure. MATERIALS AND METHODS: Forty-five New Zealand white rabbits were divided into three groups. In all groups, a rubber bag was implanted into the peritoneal cavity. In group A (n=15) the bags were kept empty. In group B (n=15) the bags were filled with normal saline in order to achieve an intra-abdominal pressure of over 12 mmHg. This pressure was kept at this level for 8 wk. In group C (n=15) the intra-abdominal rubber bags were filled with lead covered by silicone, equiponderant to the mean weight of the normal saline insufflated in group B. After 8 wk we took biopsies of the rectus abdominis muscle and counted the proportion of the different types of muscular fibers (type I, IIA, and IIB/X). RESULTS: Significant difference was found in the proportion of the three types of muscle fibers. Intra-abdominal hypertension led to an increase in type I fibers (P=0.008). No difference was noticed between groups A and C. CONCLUSIONS: The histologic response to the increased intra-abdominal pressure was an increase in type I muscle fibers. Charging with lead did not cause any significant change in the proportion of muscular fibers.

Induction of bone formation by transforming growth factor-beta2 in the non-human primate Papio ursinus and its modulation by skeletal muscle responding stem cells.

OBJECTIVES: Four adult non-human primates Papio ursinus were used to study induction of bone formation by recombinant human transforming growth factor-beta(2) (hTGF-beta(2)) together with muscle-derived stem cells. MATERIALS AND METHODS: The hTGF-beta(2) was implanted in rectus abdominis muscles and in calvarial defects with and without addition of morcellized fragments of striated muscle, harvested from the rectus abdominis or temporalis muscles. Expression of osteogenic markers including osteogenic protein-1, bone morphogenetic protein-3 and type IV collagen mRNAs from generated specimens was examined by Northern blot analysis. RESULTS: Heterotopic intramuscular implantation of 5 and 25 microg hTGF-beta(2) combined with 100 mg of insoluble collagenous bone matrix yielded large corticalized mineralized ossicles by day 30 with remodelling and induction of haematopoietic marrow by day 90. Addition of morcellized rectus abdominis muscle to calvarial implants enhanced induction of bone formation significantly by day 90. CONCLUSIONS: In Papio ursinus, in marked contrast to rodents and lagomorphs, hTGF-beta(2) induced large corticalized and vascularized ossicles by day 30 after implantation into the rectus abdominis muscle. This striated muscle contains responding stem cells that enhance the bone induction cascade of hTGF-beta(2). Induction of bone formation by hTGF-beta(2) in the non-human primate Papio ursinus may occur as a result of expression of bone morphogenetic proteins on heterotopic implantation of hTGF-beta(2); the bone induction cascade initiated by mammalian TGF-beta proteins in Papio ursinus needs to be re-evaluated for novel molecular therapeutics for induction of bone formation in clinical contexts.

Adiponectin decreases pyruvate dehydrogenase kinase 4 gene expression in obese- and diabetic-derived myotubes.

AIM: To investigate the effects of globular adiponectin (gAd) on gene expression and whether these effects are mediated through 3',5'-cyclic monophosphate-activated protein kinase in skeletal muscle myotubes obtained from lean, obese and obese diabetic individuals. METHODS: Rectus abdominus muscle biopsies were obtained from surgical patients to establish primary skeletal muscle cell cultures. Three distinct primary cell culture groups were established (lean, obese and obese diabetic; n = 7 in each group). Once differentiated, these cultures were then exposed to gAd or 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) for 6 h. RESULTS: Stimulation with gAd decreased pyruvate dehydrogenase kinase 4 (PDK4) gene expression in the obese and diabetic samples (p < or = 0.05) and increased cytochrome c oxidase (COX) subunit 4 (COXIV) gene expression in the myotubes derived from lean individuals only (p < 0.05). AICAR treatment also decreased PDK4 gene expression in the obese- and diabetic-derived myotubes (p < or = 0.05) and increased the gene expression of the mitochondrial gene, COXIII, in the lean-derived samples only (p < 0.05). CONCLUSIONS: This study demonstrated distinct disparity between myotubes derived from lean compared with obese and obese diabetic individuals following gAd and AICAR treatment. Further understanding of the regulation of PDK4 in obese and diabetic skeletal muscle and its interaction with adiponectin signalling is required as this appears to be an important early molecular event in these disease states that may improve blood glucose control and metabolic flux.

Electrophoretic and functional identification of two troponin C isoforms in toad skeletal muscle fibers.

The differential sensitivity of frog twitch and slow-tonic fibers to Ca(2+) and Sr(2+) suggests that these two fiber types express different troponin C (TnC) isoforms. To date, only one TnC isoform from anurans (resembling the mammalian fast-twitch isoform) has been isolated and characterized. In this study, we examined the possibility that anuran striated muscle contains more than one TnC isoform. Toward this end, we determined the TnC isoform composition of 198 single fibers from the rectus abdominis of the cane toad (a mixed slow-tonic and twitch muscle) and of toad cardiac muscle using a method that enables the identification of TnC isoforms on the basis of the effect of Ca(2+) on their electrophoretic mobility. The fibers were typed according to their myosin heavy chain (MHC) isoform composition. The data indicate that striated muscle of the cane toad contains two TnC isoforms, one of which (TnC-t) is present in all fibers displaying only twitch MHC isoforms and the other of which (TnC-T/c) is present in fibers displaying the tonic MHC isoform and in cardiac muscle. For a subpopulation of 15 fibers, the TnC isoform composition was also compared with Ca(2+) and Sr(2+) activation characteristics. Fibers containing the TnC-T/c isoform were approximately 3-fold more sensitive to Ca(2+), approximately 40-fold more sensitive to Sr(2+), and responded to a approximately 4.6-fold broader range of [Ca(2+)] than did fibers containing the TnC-t isoform. The Ca(2+) activation properties of toad fibers containing the TnC-T/c isoform appear to be consistent with the previously reported physiological characteristics of amphibian slow-tonic muscle fibers.

Specialized cranial muscles: how different are they from limb and abdominal muscles?

Mammalian skeletal muscle fibers can be classified into functional types by the heavy chain (MyHC) and light chain (MyLC) isoforms of myosin (the primary motor protein) that they contain. Most human skeletal muscle contains fiber types and myosin isoforms I, IIA and IIX. Some highly specialized muscle fibers in human extraocular and jaw-closing muscles express either novel myosins or unusual combinations of isoforms of unknown functional significance. Extrinsic laryngeal muscles may express the extraocular MyHC isoform for rapid contraction and a tonic MyHC isoform for slow tonic contractions. In jaw-closing muscles, fiber phenotypes and myosin expression have been characterized as highly unusual. The jaw-closing muscles of most carnivores and primates have tissue-specific expression of the type IIM or 'type II masticatory' MyHC. Human jaw-closing muscles, however, do not contain IIM myosin. Rather, they express myosins typical of developing or cardiac muscle in addition to type I, IIA and IIX myosins, and many of their fibers are hybrids, expressing two or more isoforms. Fiber morphology is also unusual in that the type II fibers are mostly of smaller diameter than type I. By combining physiological and biochemical techniques it is possible to determine the maximum velocity of unloaded shortening (V(o)) of an individual skeletal muscle fiber and subsequently determine the type and amount of myosin isoform. When analyzed, some laryngeal fibers shorten at much faster rates than type II fibers from limb and abdominal muscle. Yet some type I fibers in masseter show an opposite trend towards speeds 10-fold slower than type I fibers of limb muscle. These unusual shortening velocities are most probably regulated by MyHC isoforms in laryngeal fibers and by MyLC isoforms in masseter. For the jaw-closing muscles, this finding represents the first case in human muscle of physiological regulation of kinetics by light chains. Together, these results demonstrate that, compared to other skeletal muscles, cranial muscles have a wider repertoire of contractile protein expression and function. Molecular techniques for reverse transcription of mRNA and amplification by polymerase chain reaction have been applied to typing of single fibers isolated from limb muscles, successfully identifying pure type I, IIA and IIX and hybrid type I/IIA and IIA/IIX fibers. This demonstrates the potential for future studies of the regulation of gene expression in jaw-closing and laryngeal muscles, which have such a variety of complex fiber types fitting them for their roles in vivo.

Analysis of fiber type transformation and histology in chronic electrically stimulated canine rectus abdominis muscle island-flap stomal sphincters.

Dynamic skeletal muscle flaps are designed to perform a specific functional task through contraction and relaxation of their muscle fibers. The most commonly used dynamic skeletal flaps today are for cardiomyoplasty and anal or urinary myoplasty. Low-frequency chronic stimulation of these flaps enables them to use their intrinsic energy stores in a more efficient manner through aerobic metabolic pathways for increased endurance and improved work capacity. The purpose of this study was to (1) determine whether fiber type transformation from fatigue-prone (type II) muscle fibers to fatigue-resistant (type I) muscle fibers could be demonstrated in the authors' chronic canine stomal sphincter model where the rectus abdominis muscle was used to create a functional stomal sphincter, (2) assess whether there is any correlation between the degree of muscle fiber type transformation and the continence times, and (3) examine the long-term effects of the training regimens on the skeletal muscle fibers through histologic and volumetric analysis. Eight dynamic island-flap sphincters were created from a part of the rectus abdominis muscle in mongrel dogs by preserving the deep inferior epigastric vascular pedicle and the most caudal investing intercostal nerve. The muscular sphincters were wrapped around a blind loop of distal ileum and trained with pacing electrodes. Two different training protocols were used. In group A (n = 4), a preexisting anal dynamic graciloplasty training protocol was used. A revised protocol was used in group B (n = 4). Muscle biopsy specimens were obtained before and after training from the rectus abdominis muscle sphincter. Fiber type transformation was assessed using a monoclonal antibody directed against the fatigue-prone type II fibers. Pretraining and posttraining skeletal muscle specimens were examined histologically. A significant fiber type conversion was achieved in both group A and group B animals, with each group achieving greater than 50 percent conversion from fatigue-prone (type II) muscle fibers to fatigue-resistant (type I) muscle fibers. The continence time was different for both groups. Biopsy specimens 1 cm from the electrodes revealed that fiber type transformation was uniform throughout this region of the sphincters. Skeletal muscle fibers within both groups demonstrated a reduction in their fiber diameter and volume. Fiber type transformation is possible in this unique canine island-flap rectus abdominis sphincter model. The relative design of the flap with preservation of the skeletal muscle resting length and neuronal and vascular supply are important characteristics when designing a functional dynamic flap for stomal continence.

Age-related changes in skeletal muscle fiber composition in two swine muscles.

This study focuses the aging-related modification of skeletal fiber types in two skeletal muscles of different-age swine (6 and 18 month). Rectus abdominis and vastus medialis were employed. It was performed an immunohistochemical staining for slow fibers and it was made a quantitative evaluation, using an automatic interactive image analysis system. The percentage of slow fibers decreased in adult swine. Moreover, slow fibers in rectus abdominis were less numerous than in vastus medialis. Aging and muscle function are two important factors able to modify fiber types. Morphometric analyses can ascertain this modification for diagnostic or nourishmental purposes.

Abducens internuclear and ascending tract of deiters inputs to medial rectus motoneurons in the cat oculomotor nucleus: synaptic organization.

Abducens internuclear and ascending tract of Deiters (ATD) inputs to medial rectus motoneurons in the oculomotor nucleus are important for conjugate horizontal movements. In the present study, the organization of these separate populations of neurons and their synaptic connections with medial rectus motoneurons in the cat oculomotor nucleus have been examined by light and electron microscopy by using retrograde and anterograde axonal tracers. Consistent with the patterns of retrograde horseradish peroxidase labeling, the abducens internuclear projection is predominantly, if not exclusively, contralateral, whereas the ATD projection is exclusively ipsilateral, as demonstrated by anterograde autoradiographic and biocytin labeling. Both populations of synaptic endings contain spheroidal synaptic vesicles and establish synaptic contacts with modest postsynaptic densifications. In addition, ATD synaptic endings frequently are associated with subjunctional dense bodies and subsurface cisternae. The two populations of excitatory inputs differ, however, in their soma-dendritic distribution. The majority of abducens internuclear synaptic endings contact distal dendrites, whereas the majority of ATD synaptic endings contact proximal dendrites or somata. Abducens internuclear synaptic endings furthermore have a higher density of mitochondria than ATD synaptic endings. The more proximal location of ATD synaptic endings is consistent with the faster rise time and earlier reversal to polarizing currents of ATD excitatory postsynaptic potentials in comparison to those evoked by the abducens internuclear pathway as determined electrophysiologically. Given the differences in the physiologic signals conveyed by the abducens internuclear (eye velocity and eye position) and ATD (head velocity) pathways, the findings in this study suggest that the soma-dendritic stratification of the two inputs to medial rectus motoneurons may provide a means for the separate control of visuomotor and vestibular functions, respectively.

Evaluation of the cranial rectus abdominus muscle pedicle flap as a blood supply for the caudal superficial epigastric skin flap in dogs.

This study evaluates the cranial rectus abdominus muscle pedicle flap as the sole blood supply for the caudal superficial epigastric skin flap. This flap was composed of a cranially based rectus abdominus muscle pedicle flap that was attached to the caudal superficial epigastric island skin flap (including mammary glands 2 to 5) via the pudendoepigastric trunk. Selective angiography of the cranial epigastric artery in eight cadaver dogs proved that the arterial vasculature in the cranial rectus abdominus was contiguous with that in the caudal superficial epigastric skin flap. In the live dog study, three of six of the flaps failed because of venous insufficiency. Necrosis of mammary gland 2 occurred in two of six flaps. One of six flaps survived with the exception of the cranial most aspect of mammary gland 2. Angiography of the cranial epigastric artery proved that arterial blood supply to these flaps was intact. Histological evaluation of the failed flaps showed full-thickness necrosis of the skin and subcutaneous tissues, the presence of severe congestion, and venous thrombosis. Retrograde venous blood flow through the flap was inconsistent, and hence resulted in failure of this myocutaneous flap. Use of this flap for clinical wound reconstruction cannot be recommended.

Effects of aging on muscle fibers and collagen content of the diaphragm: a comparison with the rectus abdominis muscle.

Age-related changes of muscle fiber and collagen content of the diaphragm (DIA) and rectus abdominis (RA) muscles were examined in rats aged 1, 4, 8 and 18 months. The cross-sectional areas of all muscle fiber types (I, IIa, IIb) and the amount of collagen in both DIA and RA increased up to the age of 8 months after which a decrease in growth following a parabolic curve was found. The older DIA showed an increase in the percentage of type I fibers while in RA there was a high percentage of type IIb fibers. The aged DIA became more resistant to fatigue but at the expense of slow contraction while older RA is faster and stronger. Aged DIA and RA muscles showed a low amount of collagen with great concentration of cross-linkings leading to a tissue with low viscoelastic properties and reduced compliance.