DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2009
Marijke Hendrickx
Embryonic stem (ES) cells are pluripotent and can differentiate into every cell type of the body. Next to their potential in regenerative medicine, they are excellent tools to study embryonic development. In this work the processes of neural induction and neural patterning along the antero-posterior (A/P) body axis are studied and evidence suggests a two step mechanism for these events. First, neural induction occurs by default in the primitive ectoderm, forming anterior neural tissue and thereafter, a series of factors can posteriorize this anterior neurectoderm. In a gain-of-function/loss-of-function approach using mouse ES cells, we show that Fgf2 has the strongest caudalizing potential of all Fgfs tested. Furthermore, Bmp4 and Wnt3a, but not Wnt1, can caudalize the neurectodermal cells. The effect of the antagonists of these factors was also examined and though Dkk1 and Noggin clearly have an effect that opposes that of Wnt3a and Bmp4 respectively, they fail to anteriorize the neurectoderm. The patterning effect of SU5402, an Fgf receptor inhibitor, was rather limited. These data confirm that in the mouse, two steps are involved in neural patterning and we show that while Fgf4, Fgf8 and Wnt1 have no strong patterning effect, Fgf2, Wnt3a and Bmp4 are strong posteriorizing factors. [source]

Foxg1 is required for morphogenesis and histogenesis of the mammalian inner ear

DEVELOPMENTAL DYNAMICS, Issue 9 2006
Sarah Pauley
Abstract The forkhead genes are involved in patterning, morphogenesis, cell fate determination, and proliferation. Several Fox genes (Foxi1, Foxg1) are expressed in the developing otocyst of both zebrafish and mammals. We show that Foxg1 is expressed in most cell types of the inner ear of the adult mouse and that Foxg1 mutants have both morphological and histological defects in the inner ear. These mice have a shortened cochlea with multiple rows of hair cells and supporting cells. Additionally, they demonstrate striking abnormalities in cochlear and vestibular innervation, including loss of all crista neurons and numerous fibers that overshoot the organ of Corti. Closer examination shows that some anterior crista fibers exist in late embryos. Tracing these fibers shows that they do not project to the brain but, instead, to the cochlea. Finally, these mice completely lack a horizontal crista, although a horizontal canal forms but comes off the anterior ampulla. Anterior and posterior cristae, ampullae, and canals are reduced to varying degrees, particularly in combination with Fgf10 heterozygosity. Compounding Fgf10 heterozygotic effects suggest an additive effect of Fgf10 on Foxg1, possibly mediated through bone morphogenetic protein regulation. We show that sensory epithelia formation and canal development are linked in the anterior and posterior canal systems. Much of the Foxg1 phenotype can be explained by the participation of the protein binding domain in the delta/notch/hes signaling pathway. Additional Foxg1 effects may be mediated by the forkhead DNA binding domain. Developmental Dynamics 235:2470,2482, 2006. © 2006 Wiley-Liss, Inc. [source]

Anterior to posterior limb of the internal capsule morphology in fragile X syndrome

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 10 2009
Cherine Fahim PhD
No abstract is available for this article. [source]

Effect of oxygen inhibition on composite repair strength over time

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007
Susanna Dall'Oca
Abstract The study was aimed at examining whether an oxygen inhibition layer is required for bonding a repairing to a pre-existing composite, and to determine the time required for free radicals within a composite substrate to decay to the extent that the composite repair strength drops significantly. Ten slabs of Gradia Direct Anterior (GC Corp.) were divided into (1) control group: an interfacial oxygen inhibition layer was created by applying and light-curing two layers of bonding resin (D/E Resin, Bisco) to the slabs surface in atmospheric air; (2) experimental group: the absence of an interfacial oxygen inhibition layer was obtained by light-curing the second bonding resin layer in a nitrogen atmosphere. After 1 and 2 h, 1, 14, and 30 days of air storage, a composite repair was layered over the bonding resin. Microtensile bond strengths were measured and statistically analyzed. The curing atmosphere was not a significant factor for bond strength (p = 0.82), and time and curing atmosphere-time interaction were significant (p < 0.001). The 30 day-strengths were the lowest (p < 0.05). An oxygen-inhibited layer is not initially required for bonding to resin composite, and it takes more than 14 days before the bond strength between a pre-existing and a fresh composite drops. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source]

Male genital system and spermiogenesis of Nanorchestes amphibius (Acari: Endeostigmata: Nanorchestidae): Anatomy, histology, and evolutionary implications

JOURNAL OF MORPHOLOGY, Issue 2 2003
Gunnar Müller
Abstract In the present article the anatomy and histology of the male genital system of an endeostigmatid mite are described for the first time. The Endeostigmata probably are a paraphyletic group supposed to include the most primitive actinotrichid mites. In Nanorchestes amphibius, the testis comprises a paired germinal region connected with an unpaired glandular region. In the germinal region, spermiogenesis takes place in cysts of a somatic cell containing germ cells representing the same developmental stage. In the lumen of the glandular region, the spermatozoa are stored together with secretions of the glandular epithelium. These secretions are probably involved in the formation of spermatophores. From the glandular region, spermatozoa and secretions are released into the vasa deferentia that histologically can be divided into three sections, beginning with a short paired region with strong circular muscles serving as a sphincter, continuing with a paired proximal zone, followed by a short unpaired distal section. The distal vas deferens leads into the chitinous, unpaired ductus ejaculatorius which is followed by the progenital chamber. The ductus ejaculatorius is composed of a proximal section and a proximal, central, and anterior chamber. It is accompanied by a complex system of muscles and sclerites probably involved in the formation and ejaculation of the spermatophore. A similar organization can also be found in Prostigmata, but not in Oribatida. Anterior to the progenital chamber is located a paired accessory gland that probably produces a lipid secretion. Spermiogenesis is characterized by disintegration of the nuclear envelope, condensation of chromatin, and extensive reduction of the amount of sperm cell cytoplasm. The mature aflagellate, U-shaped spermatozoa are simple in structure and lack mitochondria and an acrosome complex. The results do not support the current view that Nanorchestidae are more closely related to Sarcoptiformes, i.e., Oribatida and Astigmata, than to Prostigmata. J. Morphol. 257:171,180, 2003. © 2003 Wiley-Liss, Inc. [source]

Anterior versus posterior approach in reconstruction of infected nonunion of the tibia using the vascularized fibular graft: potentialities and limitations

MICROSURGERY, Issue 3 2002
Sherif M. Amr M.D.
The potentialities, limitations, and technical pitfalls of the vascularized fibular grafting in infected nonunions of the tibia are outlined on the basis of 14 patients approached anteriorly or posteriorly. An infected nonunion of the tibia together with a large exposed area over the shin of the tibia is better approached anteriorly. The anastomosis is placed in an end-to-end or end-to-side fashion onto the anterior tibial vessels. To locate the site of the nonunion, the tibialis anterior muscle should be retracted laterally and the proximal and distal ends of the site of the nonunion debrided up to healthy bleeding bone. All the scarred skin over the anterior tibia should be excised, because it becomes devitalized as a result of the exposure. To cover the exposed area, the fibula has to be harvested with a large skin paddle, incorporating the first septocutaneous branch originating from the peroneal vessels before they gain the upper end of the flexor hallucis longus muscle. A disadvantage of harvesting the free fibula together with a skin paddle is that its pedicle is short. The skin paddle lies at the antimesenteric border of the graft, the site of incising and stripping the periosteum. In addition, it has to be sutured to the skin at the recipient site, so the soft tissues (together with the peroneal vessels), cannot be stripped off the graft to prolong its pedicle. Vein grafts should be resorted to, if the pedicle does not reach a healthy segment of the anterior tibial vessels. Defects with limited exposed areas of skin, especially in questionable patency of the vessels of the leg, require primarily a fibula with a long pedicle that could easily reach the popliteal vessels and are thus better approached posteriorly. In this approach, the site of the nonunion is exposed medial to the flexor digitorum muscle and the proximal and distal ends of the site of the nonunion debrided up to healthy bleeding bone. No attempt should be made to strip the scarred skin off the anterior aspect of the bone lest it should become devitalized. Any exposed bone on the anterior aspect should be left to granulate alone. This occurs readily when stability has been regained at the fracture site after transfer of the free fibula. The popliteal and posterior tibial vessels are exposed, and the microvascular anastomosis placed in an end-to-side fashion onto either of them, depending on the length of the pedicle and the condition of the vessels themselves. To obtain the maximal length of the pedicle of the graft, the proximal osteotomy is placed at the neck of the fibula after decompressing the peroneal nerve. The distal osteotomy is placed as distally as possible. After detaching the fibula from the donor site, the proximal part of the graft is stripped subperiosteally, osteotomized, and discarded. Thus, a relatively long pedicle could be obtained. To facilitate subperiosteal stripping, the free fibula is harvested without a skin paddle. In this way, the use of a vein graft could be avoided. Patients presenting with infected nonunions of the tibia with extensive scarring of the lower extremity, excessively large areas of skin loss, and with questionable patency of the anterior and posterior tibial vessels are not suitable candidates for the free vascularized fibular graft. Although a vein graft could be used between the recipient popliteal and the donor peroneal vessels, its use decreases flow to the graft considerably. These patients are better candidates for the Ilizarov bone transport method with or without free latissimus dorsi transfer. © 2002 Wiley-Liss, Inc. MICROSURGERY 22:91,107 2002 [source]

Expression of morphogenic genes in mature ovarian and testicular tissues: Potential stem-cell niche markers and patterning factors

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2006
Kristian R. von Schalburg
Abstract Morphogens are developmental regulators that modulate different tissue patterning, proliferation, differentiation, or remodeling processes in embryonic and adult tissues. Morphogens may also evoke specific regulatory programs in stem cells. Some of the morphogens involved in these processes have been characterized, while others remain unidentified. A microarray containing 3,557 salmonid cDNAs was used to compare the transcriptomes of rainbow trout precocious ovary at three different stages during second year (June, August, and October) with a reference (June normal ovary) transcriptome. During this study, we detected morphogen transcript hybridizations to salmonid elements and the study was enlarged to investigate these activities in various developmental stages of both ovary and testis. Genes from diverse development regulator families such as Anterior gradient-2, BMP, Epimorphin, Flightless, Frizzled, Notch, Tiarin, Twisted gastrulation, and Wnt were demonstrated to be expressed in the adult trout gonads. In mice or rats, expression of mammalian bmp-4, epimorphin, flightless, twisted gastrulation, and GW112 transcripts were localized to cell types isolated from the developed ovary and testis. Comparisons of salmonid and mammalian morphogens at the amino acid residue level show high similarities, suggesting functional conservation. This report provides evidence for local regulation by various morphogens and their potential to control distinct programs of gene expression in the gametes and their accessory cells during gametogenesis. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source]

Predictive Value of Admission Electrocardiogram For Multivessel Disease in Acute Anterior and Anterior-Inferior Myocardial Infarction

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2002
Turhan Kürüm M.D.
Background: Our aim was to investigate the correlation between admission ECG and coronary angiography findings in terms of predicting the culprit vessel responsible for the infarct or multivessel disease in acute anterior or anterior-inferior myocardial infarction (AMI). Methods: We investigated 101 patients with a diagnosis of anterior AMI with or without ST-segment elevation or ST-segment depression in at least two leads in Dll, III, aVF. The patients were classified as those with vessel involvement in the left anterior descending (LAD) coronary artery and patients with multivessel disease. Vessel involvement in LAD + circumflex artery (Cx) or LAD + right coronary artery (RCA) or LAD + Cx + RCA were considered as multivessel disease. Thus, (a) anterior AMI patients with reciprocal changes in inferior leads, (b) anterior AMI patients with inferior elevations, (c) all anterior AMI patients according to the ST-segment changes in the inferior region were analyzed according to the presence of LAD or multivesssel involvement. Results: Presence of ST-segment depression in aVL and V6 was significantly correlated with the presence of multivessel disease in anterior AMI patients with reciprocal changes in the inferior leads (P = 0.005 and P = 0.003, respectively). No statistically significant difference between the leads were detected in terms of ST-segment elevation in predicting vessel involvement in the two groups of anterior AMI patients with inferior elevations. When all the patients with anterior AMI were analyzed, the presence of ST-segment depression in leads aVL, V4, V5 and V6 were significantly associated with the presence of multivessel disease (P = 0.035, P = 0.010, P = 0.011, P = 0.001, respectively). Conclusions: The presence of ST-segment depression in anterolateral leads in the admission ECG of anterior AMI patients with reciprocal changes in inferior leads was associated with multivessel disease. [source]

Randomized controlled trial of laparoscopic anterior versus posterior fundoplication for gastro-oesophageal reflux disease

ANZ JOURNAL OF SURGERY, Issue 7-8 2010
Mansoor Khan
Abstract Background:, The aim of the study was to compare the effect of laparoscopic anterior and posterior fundoplication on gastro-oesophageal reflux disease by means of a prospective randomized controlled trial. Methods:, One hundred and three patients were randomised to undergo either anterior (53) or posterior (50) fundoplication. Initial enrolment and subsequent clinical appointments were undertaken 1, 3, 6 and 12 months after the procedure using a standardized questionnaire. Ambulatory pH monitoring and manometry were undertaken both preoperatively and at approximately 3 months post-procedure. Results:, The mean operating time was similar in both groups (48 versus 52 min). Two operations in each group were converted to open surgery. Post-operative dysphagia in the first month was higher in the posterior fundoplication group compared with the anterior group (at 1 month, P= 0.002; and at 3 months, P= 0.014). The number of individuals suffering from post-operative heartburn was greater in the anterior fundoplication group (at 1 month, P= 0.008; at 3 months, P < 0.001; and at 6 months, P= 0.002). Eight individuals required reoperation in the anterior group and two individuals in the posterior group (P= 0.057). Conclusion:, Anterior and posterior fundoplication each have their advantages and disadvantages. There is an increased risk of early post-operative dysphagia after posterior fundoplication. Anterior fundoplication carries a greater risk of persistent or recurrent reflux. Overall, a posterior fundoplication produces a better management option for controlling gastro-oesophageal reflux disease when compared with an anterior fundoplication technique which utilizes unilateral fixation of the gastric fundus. [source]

Five-year follow-up of a randomized clinical trial of laparoscopic total versus anterior 180° fundoplication

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 2 2005
R. Ludemann
Background: Total fundoplication for gastro-oesophageal reflux disease may be followed by unwanted side-effects. A randomized trial demonstrated that an anterior 180° partial fundoplication achieved effective reflux control and was associated with fewer side-effects in the short term than total fundoplication. This paper reports longer-term (5 year) outcomes from that trial. Methods: Between December 1995 and June 1997, 107 patients were randomized to undergo either laparoscopic total fundoplication or a laparoscopic anterior 180° fundoplication. After 5 years, 101 of 103 eligible patients (51 total, 50 anterior) were available for follow-up. Each patient was interviewed by a single blinded investigator and a standardized questionnaire was completed. The questionnaire focused on symptoms and overall satisfaction with the results of fundoplication. Results: There were no significant differences between the two groups with regard to control of heartburn or patient satisfaction with the overall outcome. Dysphagia, measured by a visual analogue score for solid food and a composite dysphagia score, was worse at 5 years after total fundoplication. Symptoms of bloating, inability to belch and flatulence were also more common after total fundoplication. Reoperation was required for dysphagia in three patients after total fundoplication and for recurrent reflux in three patients after anterior fundoplication. Conclusion: Anterior 180° partial fundoplication was as effective as total fundoplication for managing the symptoms of gastro-oesophageal reflux in the longer term. It was associated with a lower incidence of side-effects, although this was offset by a slightly higher risk of recurrent reflux symptoms. Copyright © 2004 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]

Clinical features of intraocular inflammation in Hokkaido, Japan

ACTA OPHTHALMOLOGICA, Issue 4 2009
Hirokuni Kitamei
Abstract. Purpose:, We aimed to investigate the clinical features of intraocular inflammation/uveitis in Hokkaido, Japan. Methods:, We retrospectively reviewed the medical records of 1240 uveitis patients (511 men, 729 women) who visited Hokkaido University Hospital, Sapporo, Japan between 1994 and 2003. Results:, Mean age at disease onset was 41.7 ± 17.8 years in men and 45.7 ± 18.3 years in women. Anterior, posterior and combined anterior and posterior segment intraocular inflammation accounted for 45.1%, 4.7% and 50.2% of cases, respectively. Sarcoidosis was the most frequent aetiology (14.9%), followed by Vogt,Koyanagi,Harada (VKH) disease (9.7%) and Behçet's disease (6.7%). Aetiologies in 49.8% patients were unknown. In sarcoidosis, women represented 72.4% of patients, and disease onset occurred at 35.1 ± 19.0 years of age in men and 50.3 ± 16.5 years in women. In VKH disease, 54.2% of patients were women, and disease onset took place at 45.9 ± 15.8 years in men and 46.4 ± 14.1 years in women. In Behçet's disease, men accounted for 56.6% of patients, and disease onset occurred at 35.5 ± 8.5 years in men and 44.5 ± 11.5 years in women. Conclusions:, Women were more prone to developing sarcoidosis compared with men. By contrast, men were more prone to developing Behçet's disease. The mean age at disease onset in both sarcoidosis and Behçet's disease was significantly lower in men than in women. [source]

How reliably can autoimmune hypophysitis be diagnosed without pituitary biopsy

CLINICAL ENDOCRINOLOGY, Issue 1 2010
Trevor A. Howlett
Summary Autoimmune hypophysitis is a rare chronic inflammatory condition of the pituitary gland which typically presents with hypopituitarism and a pituitary mass. Cases involving anterior pituitary alone (65%) are six times more common in women, typically presenting during pregnancy or postpartum (57%). Anterior and posterior pituitary involvement (25%) are twice as common in women, and neurohypophysis alone (10%) occurs equally in both sexes. It has a prevalence of around 5 per million, an annual incidence of 1 in 7 to 9 million and in our experience represents the known or suspected cause of 0·5% of cases of hypopituitarism, <1% of pituitary masses and 2% of nonfunctioning macro lesions presenting to an endocrine clinic. However, ,missed' cases of autoimmune hypophysitis may be the aetiology of some other unexplained cases of hypopituitarism. Clinically, headache and visual disturbance are common. Anterior hypopituitarism shows a characteristic but atypical pattern of deficiency of ACTH followed by TSH, gonadotrophins and prolactin deficiency or hyperprolactinaemia. Eighteen percent of cases have evidence of another autoimmune condition. On magnetic resonance imaging (MRI), autoimmune hypophysitis is typically symmetrical and homogeneous with thickened but undisplaced stalk in contrast to typical findings with pituitary tumours. Ultimately, the histological diagnosis of autoimmune hypophysitis can only be confirmed by surgery but a presumptive diagnosis can often be made on the basis of a combination of context and clinical features, and pituitary biopsy is not always clinically necessary for effective clinical management of the patient. [source]

Second lineage of heart forming region provides new understanding of conotruncal heart defects

CONGENITAL ANOMALIES, Issue 1 2010
Yuji Nakajima
ABSTRACT Abnormal heart development causes various congenital heart defects. Recent cardiovascular biology studies have elucidated the morphological mechanisms involved in normal and abnormal heart development. The primitive heart tube originates from the lateral-most part of the heart forming mesoderm and mainly gives rise to the left ventricle. Then, during the cardiac looping, the outflow tract is elongated by the addition of cardiogenic cells from the both pharyngeal and splanchnic mesoderm (corresponding to anterior and secondary heart field, respectively), which originate from the mediocaudal region of the heart forming mesoderm and are later located anteriorly (rostrally) to the dorsal region of the heart tube. Therefore, the heart progenitors that contribute to the outflow tract region are distinct from those that form the left ventricle. The knowledge that there are two different lineages of heart progenitors in the four-chambered heart provides new understanding of the morphological and molecular etiology of conotruncal heart defects. [source]

Right Ventricular Function in Congenital Heart Defects Assessed by Regional Wall Motion

CONGENITAL HEART DISEASE, Issue 3 2010
FSCAI, Michael R. Nihill MB
ABSTRACT Objectives., To develop a simple method to assess right ventricular function by angiography. Background., Conventional methods of evaluating right ventricular function are inaccurate, cumbersome, and expensive. Methods., We analyzed biplane right ventricular angiograms taken in the posterior,anterior and lateral projections using software to measure right ventricular volumes and regional wall motion in 78 patients with normal hearts (n = 29), atrial septal defects (ASD n = 13), pulmonary valve stenosis (PVS n = 21), and postoperative atrial switch patients (n = 15). We also measured the shortening fraction (SF) from the midtricuspid annulus to the septum and correlated various angiographic measurements with the right ventricular (RV) ejection fraction. Results., The volume-overloaded patients (ASD) had larger end diastolic volumes and increased SF compared with normal patients, while the pressure-loaded patients (PVS) had normal volumes and SF. The postoperative atrial switch patients had decreased systolic function and increased end diastolic volume. The SF for all of the patients correlated with the ejection fraction (r= 0.785, P, .0001). Conclusions., A simple measurement of the end diastolic and end systolic distance from the midtricuspid annulus to the septum (SF) provides a good index of RV function by angiography and correlates well with RV ejection fraction. [source]

Correlation of dystrophin,glycoprotein complex and focal adhesion complex with myosin heavy chain isoforms in rat skeletal muscle

ACTA PHYSIOLOGICA, Issue 4 2009
S. Masuda
Abstract Aim:, The dystrophin,glycoprotein complex (DGC) and focal adhesion complex (FAC) are transmembrane structures in muscle fibres that link the intracellular cytoskeleton to the extracellular matrix. DGC and FAC proteins are abundant in slow-type muscles, indicating the structural reinforcement which play a pivotal role in continuous force output to maintain posture for long periods. The aim of the present study was to examine the expression of these structures across fast-type muscles containing different myosin heavy chain (MHC) isoform patterns which reflect the fatigue-resistant characteristics of skeletal muscle. Methods:, We measured the expression of dystrophin and ,1 integrin (representative proteins of DGC and FAC respectively) in plantaris, extensor digitorum longus, tibialis anterior, red and white portions of gastrocnemius, superficial portion of vastus lateralis and diaphragm, in comparison with soleus (SOL) and cardiac muscle from rats. Results:, The expression of dystrophin and ,1 integrin correlated positively with the percentage of type I, IIa and IIx MHC isoforms and negatively with that of type IIb MHC isoform in fast-type skeletal muscles, and their expression was abundant in SOL and cardiac muscle. Conclusion:, Our results support the idea that DGC and FAC are among the factors that explain the fatigue-resistant property not only of slow-type but also of fast-type skeletal muscles. [source]

An enhanced level of motor cortical excitability during the control of human standing

ACTA PHYSIOLOGICA, Issue 3 2009
C. D. Tokuno
Abstract Aim:, The study examined the role of the motor cortex in the control of human standing. Methods:, Subjects (n = 15) stood quietly with or without body support. The supported standing condition enabled subjects to stand with a reduced amount of postural sway. Peripheral electrical stimulation, transcranial magnetic stimulation (TMS) or transcranial electrical stimulation (TES) was applied to elicit a soleus (SOL) H-reflex, or motor-evoked potentials (MEPs) in the SOL and the tibialis anterior (TA). Trials were grouped based on the standing condition (i.e. supported vs. normal) as well as sway direction (i.e. forward and backward) while subjects were standing normally. Results:, During normal when compared to supported standing, the SOL H-reflex was depressed (,11 ± 4%), while the TMS-evoked MEPs from the SOL and TA were facilitated (35 ± 11% for the SOL, 51 ± 15% for the TA). TES-evoked SOL and TA MEPs were, however, not different between the normal and supported standing conditions. The data based on sway direction indicated that the SOL H-reflex, as well as the SOL TMS- and TES-evoked MEPs were all greater during forward when compared to backward sway. In contrast, the TMS- and TES-evoked MEPs from the TA were smaller when swaying forward as compared to backward. Conclusions:, The results indicated the presence of an enhanced cortical excitability because of the need to control for postural sway during normal standing. The increased cortical excitability was, however, unlikely to be involved in an on-going control of postural sway, suggesting that postural sway is controlled at the spinal and/or subcortical levels. [source]

Control of the triceps surae during the postural sway of quiet standing

ACTA PHYSIOLOGICA, Issue 3 2007
C. D. Tokuno
Abstract Aim:, The present study investigated how the triceps surae are controlled at the spinal level during the naturally occurring postural sway of quiet standing. Methods:, Subjects stood on a force platform as electrical stimuli were applied to the posterior tibial nerve when the center of pressure (COP) was either 1.6 standard deviations anterior (COPant) or posterior (COPpost) to the mean baseline COP signal. Peak-to-peak amplitudes of the H-reflex and M-wave from the soleus (SOL) and medial gastrocnemius (MG) muscles were recorded to assess the efficacy of the Ia pathway. Results:, A significant increase in the Hmax : Mmax ratio for both the SOL (12 ± 6%) and MG (23 ± 6%) was observed during the COPant as compared to the COPpost condition. The source of the modulation between COP conditions cannot be determined from this study. However, the observed changes in the synaptic efficacy of the Ia pathway are unlikely to be simply a result of an altered level of background electromyographic activity in the triceps surae. This was indicated by the lack of differences observed in the Hmax : Mmax ratio when subjects stood without postural sway (via the use of a tilt table) at two levels of background activity. Conclusions:, It is suggested that the phase-dependent modulation of the triceps surae H-reflexes during the postural sway of quiet standing functions to maintain upright stance and may explain the results from previous studies, which, until now, had not taken the influence of postural sway on the H-reflex into consideration. [source]

Muscle type-specific response of PGC-1, and oxidative enzymes during voluntary wheel running in mouse skeletal muscle

ACTA PHYSIOLOGICA, Issue 3-4 2006
S. Ikeda
Abstract Aim:, It is generally accepted that endurance exercise increases the expression of peroxisome proliferator-activated receptor , coactivator-1, (PGC-1,), which governs the expression of oxidative metabolic enzymes. A previous report demonstrated that the regulation of mitochondrial protein expression in skeletal muscles in response to cold exposure depends on muscle fibre type. Cold exposure and endurance exercise are both metabolic challenges that require adjustments in mitochondrial energy metabolism, we hypothesized that the exercise-induced increase in oxidative enzymes and PGC-1, expression is higher in fast-type than in slow-type muscle. Methods:, Female ICR mice were individually housed in cages equipped with running wheel for 1, 2, 4, 6 or 8 weeks. The soleus, plantaris (PLA) and tibialis anterior (TA) muscles were then prepared from each mouse. The expression levels of PGC-1,, mitochondrial proteins and GLUT4 were evaluated by Western blotting. Results:, The expression level of PGC-1, was increased only in the PLA muscle. Furthermore, the expression levels of all mitochondrial proteins and GLUT4 in the PLA muscle were increased. In the TA muscle, although there was no increase in PGC-1, expression, the expression levels of mitochondrial proteins and GLUT4 were increased. Conclusions:, These results suggest that muscle type-specific responses occur during endurance exercise, and that the increase in PGC-1, expression is not the only factor that promotes oxidative capacity as a result of endurance exercise. [source]

Steps towards a centralized nervous system in basal bilaterians: Insights from neurogenesis of the acoel Symsagittifera roscoffensis

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2010
Henrike Semmler
Due to its proposed basal position in the bilaterian Tree of Life, Acoela may hold the key to our understanding of the evolution of a number of bodyplan features including the central nervous system. In order to contribute novel data to this discussion we investigated the distribution of ,-tubulin and the neurotransmitters serotonin and RFamide in juveniles and adults of the sagittiferid Symsagittifera roscoffensis. In addition, we present the expression pattern of the neuropatterning gene SoxB1. Adults and juveniles exhibit six serotonergic longitudinal neurite bundles and an anterior concentration of serotonergic sensory cells. While juveniles show an "orthogon-like" arrangement of longitudinal neurite bundles along the anterior-posterior axis, it appears more diffuse in the posterior region of adults. Commissures between the six neurite bundles are present only in the anterior body region of adults, while irregularly distributed individual neurites, often interconnected by serotonergic nerve cells, are found in the posterior region. Anti-RFamide staining shows numerous individual neurites around the statocyst. The orthogon-like nervous system of S. roscoffensis is confirmed by ,-tubulin immunoreactivity. In the region of highest neurotransmitter density (i.e., anterior), the HMG-box gene SrSoxB1, a transcription factor known to be involved in neurogenesis in other bilaterians, is expressed in juvenile specimens. Accordingly, SoxB1 expression in S. roscoffensis follows the typical pattern of higher bilaterians that have a brain. Thus, our data support the notion that Urbilateria already had the genetic toolkit required to form brain-like neural structures, but that its morphological degree of neural concentration was still low. [source]

Development of the endoderm and gut in medaka, Oryzias latipes

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2006
Daisuke Kobayashi
We performed an extensive analysis of endodermal development and gut tube morphogenesis in the medaka embryo by histology and in situ hybridization. The markers used in these analyses included sox17, sox32, foxA2, gata-4, -5, -6 and shh. sox17, sox32, foxA2, and gata-5 and -6 are expressed in the early endoderm to the onset of gut tube formation. Sections of medaka embryos hybridized with foxA2, a pan-endodermal marker during gut morphogenesis, demonstrated that gut tube formation is initiated in the anterior portion and that the anterior and mid/posterior gut undergo distinct morphogenetic processes. Tube formation in the anterior endoderm that is fated to the pharynx and esophagus is much delayed and appears to be independent of gut morphogenesis. The overall aspects of medaka gut development are similar to those of zebrafish, except that zebrafish tube formation initiates at both the anterior and posterior portions. Our results therefore describe both molecular and morphological aspects of medaka digestive system development that will be necessary for the characterization of medaka mutants. [source]

Immunohistochemical analysis of nervous system regeneration in chimeric individuals of Dorvillea bermudensis (Polychaeta, Dorvilleidae)

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2004
Monika C. M. Müller
In regeneration experiments, 0.5% of the two- or five-segmented fragments of the polychaete Dorvillea bermudensis were found unexpectedly transplanted: two fragments of each that were lying close together during the initial period, fused and regenerated a chimeric individual. Of the three theoretical possibilities (i.e. fusion of (i) two posterior ends; (ii) one anterior and one posterior end; (iii) or two anterior ends) only the last two were realized. The similarly oriented fragments regenerated a normal animal while anterior,anterior fused ones produced two heads or a double head. Whether the ventral cords of the fragments are located vis-à-vis or adjacent, influences the course of regeneration as well. Immunohistochemical methods (anti-acetylated ,-tubulin) in conjunction with confocal laser scanning microscopy were used to investigate the wiring pattern of the nervous systems of the grafts. In all cases, at least two supraesophageal ganglia were formed and palps, antennae and nuchal organs were innervated by the correct nerves but, in special cases, were innervated vice versa from the other brain. From these results it can be concluded that fusion of a regenerating connective with another connective results in formation of a new brain, irrespective of whether it belongs to the same nerve cord or not. [source]

Xenopus Wnt11b is identified as a potential pronephric inducer

DEVELOPMENTAL DYNAMICS, Issue 1 2010
Stéphanie Tételin
Abstract In this study, we aimed to establish if known wnt signaling molecules could be responsible for inducing early pronephros specification, using a novel and effective in vitro bioassay in Xenopus embryos. Anterior somites have the unique biological activity to signal to unspecified intermediate mesoderm to induce pronephros formation in Xenopus embryos. We have used a molecular candidate gene approach to analyze both canonical and noncanonical wnt expression in isolated anterior and posterior somites and dissected presumptive pronephros, pronephric anlagen, and pronephros from stage 12.5,35 embryos. We have identified potential candidate wnt genes expressed in the right time and place to specify pronephric development. These candidates were then directly tested in an in vitro pronephrogenesis assay based on Holtfreter sandwich cultures. Results revealed that noncanonical wnt11b and wnt11 can induce pronephros formation in vitro. Loss-of-function experiments confirmed that these genes are necessary for normal pronephros development. Developmental Dynamics 239:148,159, 2010. © 2009 Wiley-Liss, Inc. [source]

Effects of activation of hedgehog signaling on patterning, growth, and differentiation in Xenopus froglet limb regeneration

DEVELOPMENTAL DYNAMICS, Issue 8 2009
Nayuta Yakushiji
Abstract Regenerating limbs of urodele amphibians and Xenopus tadpole are reconstructed along proximal,distal, anterior,posterior (AP), and dorsal,ventral axes. In contrast, a regenerated limb of the Xenopus froglet does not have digits, and only a simple cartilaginous structure referred to as a "spike" is formed. This suggests that repatterning along the AP axis is absent in the froglet blastema. Previous studies have shown that Shh and its target genes are not expressed in the froglet blastema. In this study, we activated Hedgehog signaling in the froglet blastema and found that target genes of Shh were inducible in the mesenchyme of limb blastema. Furthermore, we found that activation of the signaling had effects on blastema cell proliferation and chondrogenesis and resulted in the formation of multiple cartilaginous structures. These findings indicate that activation of signaling that is absent in the froglet blastema is effective for improvement of limb regeneration ability in the Xenopus froglet. Developmental Dynamics, 2009. © 2009 Wiley-Liss, Inc. [source]

Genetic disruption of CYP26B1 severely affects development of neural crest derived head structures, but does not compromise hindbrain patterning

DEVELOPMENTAL DYNAMICS, Issue 3 2009
Glenn Maclean
Abstract Cyp26b1 encodes a cytochrome-P450 enzyme that catabolizes retinoic acid (RA), a vitamin A derived signaling molecule. We have examined Cyp26b1,/, mice and report that mutants exhibit numerous abnormalities in cranial neural crest cell derived tissues. At embryonic day (E) 18.5 Cyp26b1,/, animals exhibit a truncated mandible, abnormal tooth buds, reduced ossification of calvaria, and are missing structures of the maxilla and nasal process. Some of these abnormalities may be due to defects in formation of Meckel's cartilage, which is truncated with an unfused distal region at E14.5 in mutant animals. Despite the severe malformations, we did not detect any abnormalities in rhombomere segmentation, or in patterning and migration of anterior hindbrain derived neural crest cells. Abnormal migration of neural crest cells toward the posterior branchial arches was observed, which may underlie defects in larynx and hyoid development. These data suggest different periods of sensitivity of anterior and posterior hindbrain neural crest derivatives to elevated levels of RA in the absence of CYP26B1. Developmental Dynamics 238:732,745, 2009. © 2009 Wiley-Liss, Inc. [source]

Bmp2 is required for migration but not for induction of neural crest cells in the mouse

DEVELOPMENTAL DYNAMICS, Issue 9 2007
Ana Catarina Correia
Abstract Bone morphogenetic protein (BMP) signaling is essential for neural crest development in several vertebrates. Genetic experiments in the mouse have shown that Bmp2 is essential for the genesis of migratory neural crest cells. Using several markers and a transgenic reporter approach, we now show that neural crest cells are induced in Bmp2 null mutant embryos, but that these cells fail to migrate out of the neural tube. The absence of migratory neural crest cells in these mutants is not due to their elimination by cell death. The neuroectoderm of Bmp2,/, embryos fail to close and create abnormal folds both along the anterior,posterior and medio,lateral axes, which are associated with an apparent medio,lateral expansion of the neural tube. Finally, our data suggest that the molecular cascade downstream of BMP signaling in early neural crest development may be different in mouse and avian embryos. Developmental Dynamics 236:2493,2501, 2007. © 2007 Wiley-Liss, Inc. [source]

Lineage-independent mosaic expression and regulation of the Ciona multidom gene in the ancestral notochord

DEVELOPMENTAL DYNAMICS, Issue 7 2007
Izumi Oda-Ishii
Abstract The transcription factor Ciona Brachyury (Ci-Bra) plays an essential role in notochord development in the ascidian Ciona intestinalis. We characterized a putative Ci-Bra target gene, which we named Ci - multidom, and analyzed in detail its expression pattern in normal embryos and in embryos where Ci - Bra was misexpressed. Ci - multidom encodes a novel protein, which contains eight CCP domains and a partial VWFA domain. We show that an EGFP-multidom fusion protein localizes preferentially to the endoplasmic reticulum (ER), and is excluded from the nucleus. In situ hybridization experiments demonstrate that Ci - multidom is expressed in the notochord and in the anterior neural boundary (ANB). We found that the expression in the ANB is fully recapitulated by an enhancer element located upstream of Ci - multidom. By means of misexpression experiments, we provide evidence that Ci-Bra controls transcription of Ci - multidom in the notochord; however, while Ci-Bra is homogeneously expressed throughout this structure, Ci - multidom is transcribed at detectable levels only in a random subset of notochord cells. The number of notochord cells expressing Ci - multidom varies among different embryos and is independent of developmental stage, lineage, and position along the anterior,posterior axis. These results suggest that despite its morphological simplicity and invariant cell-lineage, the ancestral notochord is a mosaic of cells in which the gene cascade downstream of Brachyury is differentially modulated. Developmental Dynamics 236:1806,1819, 2007. © 2007 Wiley-Liss, Inc. [source]

Identification of molecular markers that are expressed in discrete anterior,posterior domains of the endoderm from the gastrula stage to mid-gestation

DEVELOPMENTAL DYNAMICS, Issue 7 2007
Billie A. Moore-Scott
Abstract Little is known about how the endoderm germ layer is patterned along the anterior,posterior (A-P) axis before the formation of a gut tube (embryonic day [e] 7.5,8.5 in mouse), largely due to a paucity of molecular markers of endoderm. In particular, there are few genes that mark posterior domains of endoderm that give rise to the midgut and hindgut. We have identified 8 molecular markers that are expressed in discrete domains of the gastrula stage endoderm (e7.5), suggesting that a significant level of pattern exists in the endoderm before the formation of a gut tube. Three genes Tmprss2, NM_029639, and Dsp are expressed in a presumptive midgut domain overlying the node, a domain for which molecular markers have not previously been identified. Two genes, Klf5 and Epha2 are expressed in posterior endoderm associated with the primitive streak. Expression of these five genes persists in the midgut and/or hindgut at e8.5, 9.5 and 10.5, suggesting that these genes are markers of these domains throughout these stages of development. We have identified three genes Slc39a8, Amot, and Dp1l1, which are expressed in the visceral endoderm at e7.5. Starting at e9.5, Dp1l1 is expressed de novo in the liver, midgut, and hindgut. Our findings suggest that presumptive midgut and hindgut domains are being established at the molecular level by the end of gastrulation, earlier than previously thought, and emphasize the importance of endoderm patterning before the formation of the fetal gut. Developmental Dynamics 236:1997,2003, 2007. © 2007 Wiley-Liss, Inc. [source]

Evolutionary conservation and divergence of the segmentation process in arthropods

DEVELOPMENTAL DYNAMICS, Issue 6 2007
Wim G. M. Damen
Abstract A fundamental characteristic of the arthropod body plan is its organization in metameric units along the anterior,posterior axis. The segmental organization is laid down during early embryogenesis. Our view on arthropod segmentation is still strongly influenced by the huge amount of data available from the fruit fly Drosophila melanogaster (the Drosophila paradigm). However, the simultaneous formation of the segments in Drosophila is a derived mode of segmentation. Successive terminal addition of segments from a posteriorly localized presegmental zone is the ancestral mode of arthropod segmentation. This review focuses on the evolutionary conservation and divergence of the genetic mechanisms of segmentation within arthropods. The more downstream levels of the segmentation gene network (e.g., segment polarity genes) appear to be more conserved than the more upstream levels (gap genes, Notch/Delta signaling). Surprisingly, the basally branched arthropod groups also show similarities to mechanisms used in vertebrate somitogenesis. Furthermore, it has become clear that the activation of pair rule gene orthologs is a key step in the segmentation of all arthropods. Important findings of conserved and diverged aspects of segmentation from the last few years now allow us to draw an evolutionary scenario on how the mechanisms of segmentation could have evolved and led to the present mechanisms seen in various insect groups including dipterans like Drosophila. Developmental Dynamics 236:1379,1391, 2007. © 2007 Wiley-Liss, Inc. [source]

A hypermorphic mouse Gli3 allele results in a polydactylous limb phenotype

DEVELOPMENTAL DYNAMICS, Issue 3 2007
Chengbing Wang
Abstract Gli3 protein processing to generate the Gli3 repressor is mediated by proteasome and inhibited by Hedgehog signaling. The Gli3 repressor concentration is graded along the anterior,posterior axis of the developing vertebrate limb due to posteriorly restricted Sonic hedgehog expression. In this study, we created a small deletion at the Gli3 locus (Gli3,68), which causes a half reduction in the Gli3 repressor levels and a slightly increased activity of full-length mutant protein in the limb. Mice homozygous for Gli3,68 develop one to two extra partial digits in the anterior of the limb, while mice carrying one copy of the Gli3,68 allele die soon after birth and display seven digits. These phenotypes are more severe than those found in mice lacking one wild-type Gli3 allele. The expression of dHand, Hoxd12, and Hoxd13 is anteriorly expanded in the limb, even though no up-regulation of Gli1 and Ptc RNA expression is detected. These findings suggest that a decrease in the Gli3 repressor level in combination with an increase in Gli3 full-length activity results in more severe digit patterning abnormalities than those caused by a loss of one wild-type Gli3 allele. Developmental Dynamics 236:769,776, 2007. © 2007 Wiley-Liss, Inc. [source]

Nuclear receptor NR5A2 is required for proper primitive streak morphogenesis

DEVELOPMENTAL DYNAMICS, Issue 12 2006
Cassandre Labelle-Dumais
Abstract NR5A2, also known as liver receptor homologue 1 (LRH-1) and fetoprotein transcription factor (FTF), is an orphan nuclear receptor involved in the regulation of cholesterol metabolism and steroidogenesis in the adult. NR5A2 was also shown to be expressed during early mouse embryogenesis. Consistent with its early expression pattern, a targeted disruption of this gene leads to embryonic lethality around the gastrulation period. To characterize the embryonic phenotype resulting from NR5A2 loss of function, we undertook morphological and marker gene analyses and showed that NR5A2,/, embryos display growth retardation, epiblast disorganization, a mild embryonic,extraembryonic constriction, as well as abnormal thickening of the proximo-posterior epiblast. We demonstrated that, although initial specification of the anterior,posterior axis occurred in the absence of NR5A2, primitive streak formation was impaired and neither embryonic nor extraembryonic mesoderm was generated. Moreover, although the visceral endoderm does not show major morphological abnormalities in NR5A2,/, embryos, a decrease in the expression level of HNF4 and GATA4 was observed. Aggregation experiments demonstrated that, in the presence of wild-type tetraploid cells, NR5A2 mutant cells in the epiblast are capable of undergoing normal gastrulation. Therefore, our results suggest a requirement for NR5A2 in extraembryonic tissues and identify a novel role of this gene in proper primitive streak morphogenesis. Developmental Dynamics 235:3359,3369, 2006. © 2006 Wiley-Liss, Inc. [source]

Anterior

Selected Abstracts

Anterior,posterior patterning of neural differentiated embryonic stem cells by canonical Wnts, Fgfs, Bmp4 and their respective antagonists