Muscular Region Research Articles

Muscle modifications in fibromyalgic patients revealed by surface electromyography (SEMG) analysis

BackgroundSeveral studies have been carried out in order to investigate surface electromyography (SEMG) response on fibromyalgic (FM) patients. Some studies failed to demonstrate differences between FM patients and healthy individuals while others found differences in SEMG parameters. Different muscular region have been analyzed in FM patients and heterogeneity is also produced because of the different ways in which the SEMG technique is used.The aims of this study were to evaluate muscle modifications by SEMG analysis in FM women with respect to a sample of healthy controls and to investigate the relationships between SEMG parameters and the clinical aspects of the disease.MethodsSEMG was recorded in 100 FM women (48.10 ± 11.96 yr) and in 50 healthy women (48.60 ± 11.18 yr), from the tibialis anterior and the distal part of vastus medialis muscle during isometric contraction. Initial values and rate of change of median spectral frequency (MDF) and conduction velocity (CV) of the SEMG signal were calculated.The clinical parameters "Fibromyalgia Impact Questionnaire", pain, tender points, tiredness were evaluated and the relationships between these data and the SEMG results were also studied. For the statistical analysis Mann-Whitney test, chi-square test and Spearman correlation were used.ResultsMDF absolute values and the so-called Fatigue Index (FI) were significantly lower (p < 0.001) in both muscles studied in FM patients (MDF: 93.2 μV; FI: 1.10, 0.89) with respect to healthy controls (MDF: 138.2 μV; FI: 2.41, 1.66) and a smaller reduction in the percentage values of MDF was observed in FM patients vs controls (22% vs 38%). A significant correlation was found between the SEMG parameter decrement of normalized median frequency (MNF) (%) and seriousness of FM (evaluated by means of tender points).ConclusionWe have found some interesting muscle modifications in FM patients with respect to healthy controls, regarding MDF, CV and FI values which resulted significantly lower in FM. Patients might have a different fiber recruitment or a possible atrophy of type II fibers suggesting that they are not able to reach muscle relaxation.

Normal Development of the Muscular Region of the Interventricular Septum – I. The Significance of the Ventricular Trabeculations

The structures that participate in normal ventricular septation, and to what extent they do so, are questions not yet clarified. Even less is known about how much each of the embryonic structures contributes to the topography of the mature interventricular septum (IVS). The aim of the present paper is to investigate the significance of ventricular trabeculations in the normal development of the muscular region (the middle and apical thirds) of the IVS and to determine the direction in which it grows during cardiac septation. Anatomical studies and in vivo labelling were carried out in chicken embryo hearts at stage 18HH, tracing the labels up to stage 36HH. We analysed the results by measuring the distance between the labelled structures at the beginning and end of the experiments. We demonstrate that the muscular region of the septum originates by the fusion of the ventricular trabeculations with evidence that during cardiac development, the IVS as well as the ventricular cavities grow in opposite direction to the atria.

Description of two new interstitial species of Psammodrilidae (Annelida) from Bermuda

The family Psammodrilidae (Annelida) is a group of small polychaetes hitherto containing three nominal species in Psammodriloides and Psammodrilus. Psammodrilus swedmarki, n. sp. and P. moebjergi, n. sp. are described from subtidal coarse sand in Bermuda. Both new species are interstitial, as is the monotypic Psammodriloides fauveli Swedmark, 1958, which they resemble by their small size and lack of a muscular collar region. However, studies with scanning electron microscopy show that the larger, hermaphroditic P. moebjergi possesses a pair of peristomial dorsolateral non-ciliated areas with hexagonal cells representing those of the characteristic collar region of Psammodrilus. The uncini of both species resemble those of Psammodrilus balanoglossoides Swedmark, 1952. The systematically contradicting characters support a synonymization of the two genera. An emended diagnosis of Psammodrilus and a key to the species are presented.

Tissue localization of collagenase and leucine aminopeptidase in the bovine filarial parasite Setaria cervi

BackgroundLike other helminth proteases, filarial proteases have also been shown to require for parasite survival inside the host and mediate various physiologic processes such as tissue invasion, feeding, embryogenesis and host immune evasion. Many of these proteases have shown potential for vaccines and chemotherapeutic agents against active filarial infections. Setaria cervi is a bovine filarial parasite and serves as a good parasite model for the studies in lymphatic filariasis. Recently, a 175 kDa collagenase and leucine aminopeptidase (LAP) have been purified and characterized from the bovine filarial parasite S. cervi and shown to be potential vaccine candidate and diagnostic marker, respectively for human lymphatic filariasis. However, their tissue localizations and putative roles in the parasite biology have not yet been examined and thus remain unclear. Therefore, the current study attempts to localize and explore the putative roles of these two enzymes in S. cervi.MethodsThe tissue distributions of 175 kDa collagenase and leucine aminopeptidase in S. cervi were examined by immunohistochemical and histochemical methods, respectively. Immune sera obtained from the jirds immunized with collagenase served as primary antibody, rabbit anti-mouse IgG-HRP conjugate as secondary antibody and DAB as the substrate for the immunostaining of collagenase. Leu-βNA was used as the substrate for the histochemical staining of LAP.ResultsBoth the collagenase and LAP were present in the body wall; however, they differ in their distribution pattern in different layers of body wall. Collagenase was mainly localized in epicuticle, cuticle, syncytial hypodermis and the nerve cord region whereas LAP was more concentrated in epicuticle, longitudinal muscle layers and almost absent or very faintly stained in syncytial hypodermis and nerve cord region. Both collagenase and LAP showed their common distributions in intestine, uterus and mature eggs, growing embryos and mf. Very strong immunostaining of collagenase in the outer body surface of the parasite indicates its major role in host-parasite relationship whereas the presence of LAP in muscular region suggests its role in tissue remodeling. The common presences of collagenase and LAP in the S. cervi intestine, ovary, uterus, eggs and mf suggest that they also have collaborative roles in molting, nutrition and embryogenesis. The data obtained on their immunological characterizations and their presence in important parasite organs give strong indication that they are critical for the survival of filarial parasite and thus can be good vaccine candidates and/or diagnostic markers for human lymphatic filariasis.ConclusionThe manuscript reports for the first time the tissue distribution of collagenase and LAP in the bovine filarial parasite S. cervi and discuss their putative roles in vivo. Our findings also open the avenue to examine the roles of these two proteases in vivo, which will require further experiments like using their natural substrates and/or specific inhibitors in each tissues.

Reduced tolerance of exercise in fibromyalgia may be a consequence of impaired microcirculation initiated by deficient action of nitric oxide

Although the underlying mechanism responsible for muscular fatigue and exercise intolerance remains to be elucidated, it is reported two major mechanisms, central and peripheral hypothesis. As a peripheral mechanism, there are few reports on abnormalities of the microcirculation in patients with fibromyalgia. The key point to note is that ischemia associated with a modest decline in tissue oxygen causes muscle fatigue. It has been shown that have been found low muscle levels of phosphates and abnormalities in microcirculation in fibromyalgia. Based on several novel data, production abnormalities of nitric oxide level might lead to symptoms of fatigue as a long term effect. There a vicious cycle concerning impairment of microcirculation in FM. The cycle is firstly initiated decrease of production of nitric oxide in the endothelial level by some trigger factors. Changed level of nitric oxide may cause microcirculation abnormalities in the tissue levels, muscular region. At the end of these phases, muscular fatigue and exercise intolerance may progressively develop in the FM. It is possible that this theory appears to provide a physiopathological explanation for decreased exercise capacity in patients with fibromyalgia. This paper describes a plausible mechanism for the development of exercise intolerance on microcirculation abnormalities.

Use of Synaptophysin Immunohistochemistry in Intestinal Motility Disorders

The purpose of this study was to describe synaptophysin (SY) immunoreactivity in colonic specimens from patients with Hirschsprung's disease (HD), chronic constipation (CC), or anal atresia (AA). This membrane protein is specific for the synaptic vesicles in the central and peripheral nervous system and responsible for neurotransmission. Biopsy specimens of the intestinal wall were obtained from 18 patients (age range, 2 days to 7 years). Immunohistochemistry was performed using rabbit anti-human antibodies specific for synaptophysin (DAKO). In the ganglionic colon of HD patients and others the immunoreactivity of SY-positive synapses was abundantly present in the smooth muscle layers. Distinct immunoreactivity showed ganglion cells and nerve fibers inside circular and longitudinal muscle layers. In some non-HD patients' colonic specimens SY-positive synapses were present in the muscularis mucosae. In the aganglionic colonic segment of HD-patients no immunoreactivity of synapses and ganglions was seen. In the transition zone, where ganglion cells appeared sporadically, synapses were very rarely present. In two patients from the CC group the amount of visualized synapses was clearly smaller and the concentration of ganglion cells within ganglions in these cases was much lower than usual (but still within normal ranges). In the AA group in the distal part of the atretic rectum (at the place where the fistula was cut) SY-positive synapses were present in smooth muscle layers and small dysplastic ganglions were seen in the submucosal and muscular region, but not in large numbers. These patients had a normal distribution of ganglion cells and synapses at the place of colostomy. Synaptophysin immunohistochemistry is an indirect labeling method with a high detection rate for intestinal ganglion cells by demonstrating their synapses. Changed intestinal distributions of SY-positive synaptic vesicles usually accompany colonic ganglion cell disorders. The pattern of SY-positive synapses distribution in circular and longitudinal colonic muscles and intermuscular ganglions can reflect functional disturbances of large bowel motility and could be helpful in the description of the innervation status of colonic specimens in HD patients.

Shape and tension distribution of the active canine diaphragm

Both diaphragm shape and tension contribute to transdiaphragmatic pressure, but of the three variables, tension is most difficult to measure. We measured transdiaphragmatic pressure and the global shape of the in vivo canine diaphragm and used principles of mechanics to compute the tension distribution. Our hypotheses were that 1) tension in the active diaphragm is nonuniform with greater tension in the central tendon than in the muscular regions; 2) maximum tension is essentially oriented in the muscle fiber direction, whereas minimum tension is orthogonal to the fiber direction; and 3) during submaximal activation change in the in vivo global shape is small. Metallic markers, each 2 mm in length, were implanted surgically on the peritoneal surface of the diaphragm at 1.5- to 2.0-cm intervals along the muscle bundles at the midline, ventral, middle, and dorsal regions of the left costal diaphragm and along a muscle bundle of the crural diaphragm. Postsurgery, a biplane videofluoroscopic system was used to determine the in vivo three-dimensional coordinates of the markers at end expiration and end inspiration during quiet breathing as well as at end-inspiratory efforts against an occluded airway at lung volumes of functional residual capacity and at one-third maximum inspiratory capacity increments in volume to total lung capacity. A surface was fit to the marker locations using a two-dimensional spline algorithm. Diaphragm surface was modeled as a pressurized membrane, and tension distribution in the active diaphragm was computed using the ANSYS finite element program. We showed that the peak of the diaphragm dome was closer to the ventral surface than to the dorsal surface and that there was a depression or valley in the crural region. In the supine position, during inspiratory efforts, the caudal displacement of the dorsal region of the diaphragm was greater than that of the dome, and the valley along the crural diaphragm was accentuated. In contrast, at lower lung volumes in the prone posture, the caudal displacement of the dome was greater than that of the crural region. At end of inspiration, transdiaphragmatic pressure was approximately 6.5 cmH2O, and tensions were nonuniform in the diaphragm. Maximum principal stress sigma(1) of central tendon was found to be greater than sigma(1) of the costal region, and that was greater than sigma(1) of the crural region, with values of 14-34, 14-29, and 4-14 g/cm, respectively. The corresponding data of the minimum principal stress sigma(2) were 9-18, 3-9, and 0-1.5 g/cm, respectively. Maximum principal tension was approximately parallel to the muscle fibers, whereas minimum tension was essentially orthogonal to the longitudinal direction of the muscle fibers. In the muscular region, sigma(1) was approximately 3-fold sigma(2), whereas in the central tendon, sigma(1) was only approximately 1.5-fold sigma(2.).

Passive mechanics of muscle tendinous junction of canine diaphragm

The diaphragmatic muscle tendon is a biaxially loaded junction in vivo. Stress-strain relations along and transverse to the fiber directions are important in understanding its mechanical properties. We hypothesized that 1) the central tendon possesses greater passive stiffness than adjacent muscle, 2) the diaphragm muscle is anisotropic, whereas the central tendon near the junction is essentially isotropic, and 3) a gradient in passive stiffness exists as one approaches the muscle-tendinous junction (MTJ). To investigate these hypotheses, we conducted uniaxial and biaxial mechanical loading on samples of the MTJ excised from the midcostal region of dog diaphragm. We measured passive length-tension relationships of the muscle, tendon, and MTJ in the direction along the muscle fibers as well as transverse to the fibers. The MTJ was slack in the unloaded state, resulting in a J-shaped passive tension-strain curve. Generally, muscle strain was greater than that of MTJ, which was greater than tendon strain. In the muscular region, stiffness in the direction transverse to the fibers is much greater than that along the fibers. The central tendon is essentially inextensible in the direction transverse to the fibers as well as along the fibers. Our data demonstrate the existence of more pronounced anisotropy in the muscle than in the tendon near the junction. Furthermore, a gradient in muscle stiffness exists as one approaches the MTJ, consistent with the hypothesis of continuous passive stiffness across the MTJ.

Frequent translocalization of β-catenin in gastric cancers and its relevance to tumor progression

Altered distribution of beta-catenin has been found in many human malignancies including gastric cancer, but its reason(s) and biological implications have not yet been fully clarified. By the methods of frozen tissue array-based immunohistochemistry, RT-PCR and PCR-SSCP followed by DNA sequencing, the patterns of beta-catenin distribution in the subtypes of gastric cancers and their premalignant and non-cancerous counterparts were examined and the potential correlation of beta-catenin alteration with invasion was elucidated. Membranous beta-catenin was detected constantly in non-cancerous mucosa but became reduced or absent in cancer tissues. The cytoplasmic and nuclear accumulation of beta-catenin could be observed in premalignant (atrophic gastritis and intestinal metaplasia) and cancer tissues, particularly in those infiltrated into deep muscular region. beta-catenin mutation was not detected in all of tissue samples with and without translocalized beta-catenin. These results indicate that beta-catenin translocalization is a common phenomenon in gastric cancers as well as their related lesions. The loss of membranous and the gain of cytoplasmic and nuclear beta-catenin in gastric cancers checked in this study are not due to the mutational event. beta-catenin molecules translocalized in the nuclei are closely correlated with tumor invasion.

Collagen remodelling in the guinea-pig uterine cervix at term is associated with a decrease in progesterone receptor expression.

In human and guinea-pig parturition, progesterone withdrawal and estrogen action are not mediated by changes in their circulating levels. Instead, these events might be promoted by changes in the responsiveness of the uterus and cervix to progesterone and estrogen via changes in their receptors. In this study, the guinea-pig model was used to investigate whether high levels of progesterone and estrogen at term are associated with regional changes in PR and ERalpha levels in uterus and cervix. PR and ERalpha profiles were established in both subepithelium and the muscular layer of the cervix and the lower uterine horns during pregnancy, parturition and postpartum; while collagen remodelling was measured in the subepithelium. Our data showed that collagen remodelling involved in cervical ripening is temporally and spatially associated with a decrease in PR, whereas high expression of ERalpha is observed. This association was found in the subepithelium of the cervical tissue but not in the same region of the uterus. The muscular region of the cervix and uterus also present a transiently decreased expression of PR while ERalpha levels remain high. Thus, the present results indicate that, before parturition, diminished responsiveness of the cervix to progesterone might be caused by a decrease in PR levels and that this may be the mechanism of functional progesterone withdrawal. The guinea-pig was further validated as an animal model for human parturition studies.

The axial location of structural regions in the urethra: a magnetic resonance study in nulliparous women

Objective To define and quantify the appearance and location of distinct regions of the bladder neck and urethra by using axial magnetic resonance images from healthy, continent, nulliparous women. Methods Seventy-eight asymptomatic, healthy, nulliparous women (mean age 29.2 ± 5.4 years) volunteered for this study. All women were proven continent on urodynamic examination. Axial proton density magnetic resonance images of the pelvic floor were analyzed at 5-mm intervals. A geometric origin was established at the internal urethral meatus. The presence or absence of each of six structural regions—the bladder base, bladder neck, striated urethral sphincter, compressor urethrae and urethrovaginal sphincter, perineal membrane, and distal urethra—was then noted in each more distal image. The proportion of women in whom a structural region was seen at each 5-mm interval was recorded. Results The striated urogenital sphincter was observed at 5–25 mm distal to the bladder base. It was observed 10 and 15 mm below the bladder base in 91% (95% confidence interval [CI] 85%, 98%) and 99% (95% CI 97%, 100%), respectively, of all women. The perineal membrane, marking the distal end of the muscular urethra, was located 20–35 mm distal to the bladder base. The length of the muscular region of the urethra ranged from 20 to 35 mm (mean 24 mm, 95% CI 24, 25 mm). Conclusion Magnetic resonance images allow the normal appearance and location of urethral and bladder neck structures to be quantified in healthy, continent, nulliparous women.

Reconstruction of diaphragm using autologous fascia lata: an experimental study in dogs

Background. We investigated whether fascia lata is an appropriate material for reconstruction of the diaphragm. Methods. A diaphragmatic defect (2 cm by 5 cm) was reconstructed with a patch of autologous fascia lata in the experimental group (n = 12) and with expanded polytetrafluoroethylene in the control group (n = 12). Maximal tensile strength at the sutured region was measured serially. Results. The maximal tensile strength at the sutured region reconstructed with the fascia lata was 1.14 ± 0.50 kgf 15 days and 2.04 ± 0.94 kgf 30 days after operation. The values were higher than those of expanded polytetrafluoroethylene ( p < 0.0001). These values of fascia lata were close to the original maximal tensile strength of the muscular region of the diaphragm (1.52 to 1.66 kgf). Conclusions. Reconstruction of diaphragm using autologous fascia lata is safe, easy, and inexpensive, and provides smooth wound healing. The only disadvantage is the necessity of a femoral incision for harvest; nevertheless, it may be worthwhile to use fascia lata in clinical trials to further assess its suitability as a reconstruction material.

Anatomical study of the diaphragm of the opossum (Didelphis albiventris).

The anatomical characteristics of the South American opossum diaphragm were described. Five male and seven female adult opossums, weighing between 700 and 1110 g, were used. Animals were killed by ether inhalation saturation. The abdominal and thoracic walls were dissected and opened, the viscerae were removed and the diaphragm anatomy was described and photographed in situ. After diaphragm removal, some dimensional data were taken and tabled. Primary branches of the phrenic nerves were dissected under a surgical microscope. The secondary branches were studied and described by transillumination after clarification in acetic acid. The opossum diaphragm is domed and has a mean area of 54.33 +/- 3.8 cm2. Well-identified costal, sternal and lumbar parts form the peripheral muscular region. The central tendinous region presents with a V-like form. Three folioles comprise the phrenic centre and present different dimensions. The caudal vena cava passes through its foramen between the ventral and right dorsal folioles. Both right and left phrenic nerves present one ventral branch and one dorsolateral trunk in 50.0% and 66.67% of the cases, respectively.

Opening angles and residual strains in normal rat trachea

The no-load state and zero-stress state of the normal rat trachea were analyzed. It was found that there exist compressive residual strains in the inner wall region of the rat trachea and tensile residual strains in the outer wall region. The fact that the opening angle of the rat trachea cut at the cartilaginous region is significantly larger than that cut at the muscular portion shows that residual strains exist mainly in the muscular region in the rat trachea. It was also indicated that the opening angles and residual strains expressed by cutting at the muscular portion are basically identical along longitudinal location and those expressed by cutting in the cartilaginous region tend to increase in the longitudinal direction in the normal rat, and that there exists quantitatively positive correlation between the opening angles and residual strains in rat trachea. The results will help to further understand the opening angles and residual strains in the trachea and study tracheal remodeling in response to mechanical environment.

Emergency psychiatry: extrapyramidal side effects in the psychiatric emergency service.

T benefits that neuroleptic medications provide in treating psychotic symptomatology in schizophrenia are well established (1). In addition, neuroleptic medications are often used to treat acute, psychotic episodes not related to schizophrenia, such as micropsychotic episodes among patients with personality disorders or posttraumatic stress disorder; acute psychosis from LSD, PCP, or cocaine intoxication; or psychotic states related to dementias and other neurological conditions. Neuroleptic medications are also often used for their acute sedative properties in treating agitated patients, both in psychiatric and nonpsychiatric settings. In tandem with the benefits of neuroleptic medications are significant risks associated with their use. These risks are primarily acute and chronic neurological adverse effects involving voluntary and involuntary musculature. This column focuses primarily on the acute side effects of neuroleptics, generally referred to as extrapyramidal side effects. These side effects are often seen as sequelae of acute neuroleptic treatment, often resulting in presentation to a psychiatric emergency service, such as an emergency room, a psychiatric emergency clinic in an emergency room, or a psychiatric consultation service in a general hospital. We discuss diagnosis, proposed etiology, and treatment of extrapyramidal side effects in the acute clinical setting.

Structural and ultrastructural description of the venom gland of Loxosceles intermedia (brown spider)

The brown spider, genus Loxosceles, is becoming of great medical importance, with envenomation (Loxoscelism) occurring throughout the world. The biological activities of the brown spider venom usually include dermonecrotic lesions at the bite site accompanied by hemolytic and haemorrhagic effects and also by renal failure. The objective of the present study was to describe the histology of the venom gland of L. intermedia using glands from adult spiders which were investigated by light microscopy, using immunohistochemical and staining methods, by transmission electron microscopy, and by scanning electron microscopy. The organization of the venom gland of Loxosceles intermedia follows the general architecture of spiders' venom glands. Using light microscopy and transmission electron microscopy we observed that the venom glands of L. intermedia present two layers of striated muscle fibers, an external layer and an internal layer in touch with an extracellular matrix which is a basement membrane structure and a fibrillar collagen matrix separating the muscular region from epithelial cells of the venom gland. Muscle cells are multinucleated, with nuclei peripherally placed and their cytoplasm rich in sarcoplasmic reticulum, myofibrills and continuous Z lines. By using scanning electron microscopy we can detect muscular cells from external layer as branching cells. Epithelial cells have their cytosol extremely rich in rough endoplasmic reticulum, mitochondria collection, Golgi apparatus, interdigitating membranes and secretory vesicles that ultimately accumulate the venom, a complex protein mixture.

Ultrastructure of Infective Larvae (L3) of Onchocerca volvulus (Nematoda: Filarioidea) Developed in Simulium yahense in Liberia

Third-stage infective larvae of Onchocerca volvulus were examined to elucidate the ultrastructure and the interrelations of the stoma, esophagus, intestine, and nervous system. The alimentary canal involves a cuticularized stoma with a triradiate lumen that is continuous with a similar triradiate lumen in the muscular region of the esophagus. The lumen wall may be laterally appressed or opened into a stellate form in the glandular region. Posteriad from the esophagointestinal valve, the cylindroid lumen becomes partially occluded with microvilli formed by the evaginations of the apical membranes of the intestinal epithelium. Cross sections, through this region reveal that groups of 5 radiating epithelial cells are joined near the lumen surface by junctional complexes. The alimentary canal terminates via a rectal valve and channel supported by somatic and neural cells. The central nervous system consists of a nerve ring that surrounds the muscular region of the esophagus. Related neurons support chemoreceptors and tactoreceptors of sensilla and the extensive coelomyarian and meromyarian somatic muscles. Extensive accumulations of glycogen rosettes are present in many of the muscle and hypodermal cells.

Imaging of the orifice of the left ventricular outflow tract: technique and initial results

The mechanism of left ventricular outflow tract (LVOT) obstruction in the patient after mitral valve replacement or repair was examined with the aid of 2D echocardiography. For the interpretation of the spatial relationship between the aortic root and mitral annulus, however, the 2D display is sometimes inadequate since it may not simultaneously capture these structures in each center. We developed a method to clarify this relationship in 3D based on magnetic resonance images. We defined the office of the left ventricular outflow tract (LVOT orifice), consisting of, in turn, a muscular region, i.e., edge of the interventricular septum, and an annular region, i.e., the annulus of the anterior mitral leaflet. In this paper we present image data obtained from one of eight normal subjects examined and compare this with data of one of two patients who preoperatively suffered degenerative mitral regurgitation and subsequently underwent chordal-preserving mitral valve replacement, in which anterior chordae were reattached to the anterior annulus. In the normal subject, the mitral annulus exhibited a flexible change in shape during the systole, maintaining sufficient LVOT orifice size. In the patient, the prosthetic valve exhibited translational motion during systole, resulting in dynamic LVOT obstruction. This phenomenon was also observed in one other case. Furthermore, the lateral view of the LVOT orifice revealed a projection of the prosthetic valve into the LVOT, causing mechanical LVOT obstruction. The finding that translational motion of the prosthetic valve with an inflexible mitral annulus results in dynamic LVOT obstruction may support the hypothesis that annular rigidity causes dynamic LVOT obstruction after mitral valve repair with a rigid prosthetic ring.

Effects of transverse fiber stiffness and central tendon on displacement and shape of a simple diaphragm model.

Our previous experimental results (A. M. Boriek, S. Lui, and J. R. Rodarte. J. Appl. Physiol. 75: 527-533, 1993 and A. M. Boriek, T. A. Wilson, and J. R. Rodarte. J. Appl. Physiol. 76: 223-229, 1994) showed that 1) costal diaphragm shape is similar at functional residual capacity and end inspiration regardless of whether the diaphragm muscle shortens actively (increased tension) or passively (decreased tension); 2) diaphragmatic muscle length changes minimally in the direction transverse to the muscle fibers, suggesting the diaphragm may be inextensible in that direction; and 3) the central tendon is not stretched by physiological stresses. A two-dimensional orthotropic material has two different stiffnesses in orthogonal directions. In the plane tangent to the muscle surface, these directions are along the fibers and transverse to the fibers. We wondered whether orthotropic material properties in the muscular region of the diaphragm and inextensibility of the central tendon might contribute to the constancy of diaphragm shape. Therefore, in the present study, we examined the effects of stiffness transverse to muscle fibers and inextensibility of the central tendon on diaphragmatic displacement and shape. Finite element hemispherical models of the diaphragm were developed by using pressurized isotropic and orthotropic membranes with a wide range of stiffness ratios. We also tested heterogeneous models, in which the muscle sheet was an orthotropic material, having transverse fiber stiffness greater than that along the fibers, with the central tendon being an inextensible isotropic cap. These models revealed that increased transverse stiffness limits the shape change of the diaphragm. Furthermore, an inextensible cap simulating the central tendon dramatically limits the change in shape as well as the membrane displacement in response to pressure. These findings provide a plausible mechanism by which the diaphragm maintains similar shapes despite different physiological loads. This study suggests that changes of diaphragm shape are restricted because the central tendon is essentially inextensible and stiffness in the direction transverse to the muscle fibers is greater than stiffness along the fibers.

Evaluation of normal and abnormal hyoid bone movement during swallowing by use of ultrasound duplex-Doppler imaging

We developed a new method to analyze normal and abnormal movements of the hyoid muscular region as an indicator of hyoid bone motion during swallowing using ultrasound duplex-Doppler imaging. Hyoid bone motion can be monitored by studying the Doppler shift spectra and B-mode images produced by ultrasound duplex imaging of the hyoid region muscular attachments. We can accurately determine swallowing duration and trajectory of hyoid bone movement. This procedure can assist in discriminating between normal and abnormal movements of the hyoid bone and the surrounding muscles during swallowing. This method appears to be a highly consistent measure. We suggest that Doppler spectrum analysis can be used for defining hyoid position and displaying accurate movement, which may be useful in the diagnosis of swallowing disorders.