Changing patterns of cognitive-motor interference (CMI) over time during recovery from stroke

Objective: To explore the extent and nature of change in cognitive-motor interference (CMI) among rehabilitating stroke patients who showed dual-task gait decrement at initial assessment. Design: Experimental, with in-subjects, repeated measures design. Setting: Rehabilitation centre for adults with acquired, nonprogressive brain injury. Subjects: Ten patients with unilateral stroke, available for reassessment 1-9 months following their participation in a study of CMI after brain injury. Measures: Median stride duration; mean word generation. Methods: Two x one-minute walking trials, two x one-minute word generation trials, two x one-minute trials of simultaneous walking and word generation; 10-metre walking time; Barthel ADL Scale score. Results: Seven out of ten patients showed reduction over time in dual-task gait decrement. Three out of ten showed reduction in cognitive decrement. Only one showed concomitant reduction in gait and word generation decrement. Conclusion: Extent of CMI during relearning to walk after a stroke reduced over time in the majority of patients. Effects were more evident in improved stride duration than improved cognitive performance. Measures of multiple task performance should be included in assessment for functional recovery.

Dynamics of brand competition: Effects of unobserved social networks

Brand competition is modelled using an agent based approach in order to examine the long run dynamics of market structure and brand characteristics. A repeated game is designed where myopic firms choose strategies based on beliefs about their rivals and consumers. Consumers are heterogeneous and can observe neighbour behaviour through social networks. Although firms do not observe them, the social networks have a significant impact on the emerging market structure. Presence of networks tends to polarize market share and leads to higher volatility in brands. Yet convergence in brand characteristics usually happens whenever the market reaches a steady state. Scale-free networks accentuate the polarization and volatility more than small world or random networks. Unilateral innovations are less frequent under social networks.

Riluzole neuroprotection in a parkinson’s disease model involves suppression of reactive astrocytosis but not GLT-1 regulation

Background Riluzole is a neuroprotective drug used in the treatment of motor neurone disease. Recent evidence suggests that riluzole can up-regulate the expression and activity of the astrocyte glutamate transporter, GLT-1. Given that regulation of glutamate transport is predicted to be neuroprotective in Parkinson's disease, we tested the effect of riluzole in parkinsonian rats which had received a unilateral 6-hydroxydopamine injection into the median forebrain bundle. Results Rats were treated with intraperitoneal riluzole (4 mg/kg or 8 mg/kg), 1 hour before the lesion then once daily for seven days. Riluzole produced a modest but significant attenuation of dopamine neurone degeneration, assessed by suppression of amphetamine-induced rotations, preservation of tyrosine hydroxylase positive neuronal cell bodies in the substantia nigra pars compacta and attenuation of striatal tyrosine hydroxylase protein loss. Seven days after 6-hydroxydopamine lesion, reactive astrocytosis was observed in the striatum, as determined by increases in expression of glial fibrillary acidic protein, however the glutamate transporter, GLT-1, which is also expressed in astrocytes was not regulated by the lesion. Conclusions The results confirm that riluzole is a neuroprotective agent in a rodent model of parkinson’s disease. Riluzole administration did not regulate GLT-1 levels but significantly reduced GFAP levels, in the lesioned striatum. Riluzole suppression of reactive astrocytosis is an intriguing finding which might contribute to the neuroprotective effects of this drug.

Negative blood oxygen level dependence in the rat: a model for investigating the role of suppression in neurovascular coupling

Modern neuroimaging techniques rely on neurovascular coupling to show regions of increased brain activation. However, little is known of the neurovascular coupling relationships that exist for inhibitory signals. To address this issue directly we developed a preparation to investigate the signal sources of one of these proposed inhibitory neurovascular signals, the negative blood oxygen level-dependent (BOLD) response (NBR), in rat somatosensory cortex. We found a reliable NBR measured in rat somatosensory cortex in response to unilateral electrical whisker stimulation, which was located in deeper cortical layers relative to the positive BOLD response. Separate optical measurements (two-dimensional optical imaging spectroscopy and laser Doppler flowmetry) revealed that the NBR was a result of decreased blood volume and flow and increased levels of deoxyhemoglobin. Neural activity in the NBR region, measured by multichannel electrodes, varied considerably as a function of cortical depth. There was a decrease in neuronal activity in deep cortical laminae. After cessation of whisker stimulation there was a large increase in neural activity above baseline. Both the decrease in neuronal activity and increase above baseline after stimulation cessation correlated well with the simultaneous measurement of blood flow suggesting that the NBR is related to decreases in neural activity in deep cortical layers. Interestingly, the magnitude of the neural decrease was largest in regions showing stimulus-evoked positive BOLD responses. Since a similar type of neural suppression in surround regions was associated with a negative BOLD signal, the increased levels of suppression in positive BOLD regions could importantly moderate the size of the observed BOLD response.

Dissociating between object affordances and spatial compatibility effects using early response components

Perception and action are tightly linked: objects may be perceived not only in terms of visual features, but also in terms of possibilities for action. Previous studies showed that when a centrally located object has a salient graspable feature (e.g., a handle), it facilitates motor responses corresponding with the feature's position. However, such so-called affordance effects have been criticized as resulting from spatial compatibility effects, due to the visual asymmetry created by the graspable feature, irrespective of any affordances. In order to dissociate between affordance and spatial compatibility effects, we asked participants to perform a simple reaction-time task to typically graspable and non-graspable objects with similar visual features (e.g., lollipop and stop sign). Responses were measured using either electromyography (EMG) on proximal arm muscles during reaching-like movements, or with finger key-presses. In both EMG and button press measurements, participants responded faster when the object was either presented in the same location as the responding hand, or was affordable, resulting in significant and independent spatial compatibility and affordance effects, but no interaction. Furthermore, while the spatial compatibility effect was present from the earliest stages of movement preparation and throughout the different stages of movement execution, the affordance effect was restricted to the early stages of movement execution. Finally, we tested a small group of unilateral arm amputees using EMG, and found residual spatial compatibility but no affordance, suggesting that spatial compatibility effects do not necessarily rely on individuals’ available affordances. Our results show dissociation between affordance and spatial compatibility effects, and suggest that rather than evoking the specific motor action most suitable for interaction with the viewed object, graspable objects prompt the motor system in a general, body-part independent fashion

Radiographic Findings Among Children Hospitalized With Severe Community-Acquired Pneumonia

Background: Community-acquired pneumonia (CAP) is a leading cause of childhood death. There are few published reports of radiographic findings among children with severe CAP. Objective: To describe chest X-ray (CXR) findings and assess association between these radiographic findings and pneumococcal isolation in children with severe CAP. Methods: A prospective, multicenter, observational study was conducted in 12 centers in Argentina, Brazil, and the Dominican Republic. Children aged 3-59 months, hospitalized with severe pneumonia, were included. On admission, blood and pleural effusion cultures were performed. Streptococcus pneumoniae was identified according to standard procedures in the respective national reference laboratory. Chest X-rays were taken on admission and read before the culture results were reported. Results: Out of 2,536 enrolled patients, 283 (11.2%) had S. pneumoniae isolated, in 181 cases (7.1%) from blood. The follow radiographic patterns were observed: alveolar infiltrate (75.2%), pleural effusion (15.6%), and interstitial infiltrate (9.2%). Overall, pleural effusion was associated with pneumococcal isolation and pneumococcal bacteremia (P < 0.001). Infiltrates were unilateral (78.7%) or bilateral (21.3%), right-sided (76%) or left-sided (24%), in the lower lobe (53.6%) or the upper lobe (46.4%). Multivariate analysis including patients with affection of only one lobe showed that upper lobe affection and pleural effusion were associated with pneumococcal isolation (OR 1.8, 95% CI, 1.3-2.7; OR 11.0, 95% CI, 4.6-26.8, respectively) and with pneumococcal bacteremia (OR 1.7, 95% CI, 1.2-2.6; OR 3.1, 95% CI, 1.2-8.0, respectively). Conclusions: Three-quarters of the patients studied had alveolar infiltrates. Upper lobe compromising and pleural effusion were associated with pneumococcal invasive disease. Pediatr Pulmonol. 2010; 45:1009-1013. (C) 2010 Wiley-Liss, Inc.

A Clinical Study of 406 Sinus Augmentations With 100% Anorganic Bovine Bone

Background: The aim of the present study is to evaluate the use of anorganic bovine bone (ABB) associated with a collagen membrane (CM) for a sinus graft by means of clinical, histologic, and radiographic parameters in cases with bone availability <= 7 mm. A preliminary evaluation consisted of a clinical examination, computed tomography (CT), and a panoramic x-ray. Methods: Ninety-two patients requiring bilateral sinus grafts and 222 requiring unilateral procedures (total: 406 sinuses) participated in this study. A total of 1,025 implants were placed in the grafted sinuses. A total of 118 implants were placed simultaneously with the sinus graft (one stage), and 907 implants were placed in a subsequent surgery (two stages), 6 to 12 months after the graft was performed. In seven cases, a biopsy was harvested for histomorphometric analysis. Recall appointments were scheduled every 6 months, and panoramic and periapical x-rays were required every year for 3 years. Results: Among 1,025 implants, 19 were lost (survival rate: 98.1%). The difference in survival rates for implants placed in native bone: <= 3 mm (98.1%), >3 to <= 5 mm (98.6%), and >5 to <= 7 mm (97.0%) was not statistically significant (P = 0.3408). The survival rates for implants with rough and machined surfaces (98.6% and 97.0%, respectively) were not statistically significant (P = 0.0840). The histomorphometric analysis showed new bone formation (39.0% +/- 12%), marrow space (52.9% +/- 9.3%), and residual ABB (8% +/- 2.7%). Conclusion: Our results indicated that 1,025 implants placed in sinuses grafted exclusively with ABB combined with CM led to an excellent and predictable survival rate of 98.1%. J Periodontol 2009;80:1920-1927.

A Longitudinal Three-Center Study of Dental Arch Relationship in Patients With Bilateral Cleft Lip and Palate

Objective: To compare and evaluate longitudinally the dental arch relationships from 4.5 to 13.5 years of age with the Bauru-BCLP Yardstick in a large sample of patients with bilateral cleft lip and palate (BCLP). Design: Retrospective longitudinal intercenter outcome study. Patients: Dental casts of 204 consecutive patients with complete BCLP were evaluated at 6, 9, and 12 years of age. All models were identified only by random identification numbers. Setting: Three cleft palate centers with different treatment protocols. Main Outcome Measures: Dental arch relationships were categorized with the Bauru-BCLP yardstick. Increments for each interval (from 6 to 9 years, 6 to 12 years, and 9 to 12 years) were analyzed by logistic and linear regression models. Results: There were no significant differences in outcome measures between the centers at age 12 or at age 9. At age 6, center B showed significantly better results (p = .027), but this difference diminished as the yardstick score for this group increased over time (linear regression analysis), the difference with the reference category (center C, boys) for the intervals 6 to 12 and 9 to 12 years being 10.4% (p = .041) and 12.9% (p = .009), respectively. Conclusions: Despite different treatment protocols, dental arch relationships in the three centers were comparable in final scores at age 9 and 12 years. Delaying hard palate closure and employing infant orthopedics did not appear to be advantageous in the long run. Premaxillary osteotomy employed in center B appeared to be associated with less favorable development of the dental arch relationship between 9 and 12 years.

22q11 deletion syndrome and limb anomalies: Report on two Brazilian patients

Objective: To report on two Brazilian patients with chromosome 22q11 deletion who presented with velopharyngeal insufficiency, congenital heart anomalies, developmental delay, and limb anomalies. The pattern of limb anomalies in these patients, which range from ectrodactyly to limb synostosis, is very uncommon in 22q11 deletion syndrome. Conclusion: These patients widen the spectrum of clinical signs of the 22q11 deletion syndrome and alert researchers to conduct additional investigation in patients with limb involvement with velopharyngeal insufficiency and/or cardiac anomalies, along with developmental delay.

Endogenous-like orienting of visual attention in rats

This study investigated the orienting of visual attention in rats using a 3-hole nose-poke task analogous to Posner, Information processing in cognition: the Loyola Symposium, Erlbaum, Hillsdale, (1980) covert attention task for humans. The effects of non-predictive (50% valid and 50% invalid) and predictive (80% valid and 20% invalid) peripheral visual cues on reaction times and response accuracy to a target stimulus, using Stimuli-Onset Asynchronies (SOAs) varying between 200 and 1,200 ms, were investigated. The results showed shorter reaction times in valid trials relative to invalid trials for both subjects trained in the non-predictive and predictive conditions, particularly when the SOAs were 200 and 400 ms. However, the magnitude of this validity effect was significantly greater for subjects exposed to predictive cues, when the SOA was 800 ms. Subjects exposed to invalid predictive cues exhibited an increase in omission errors relative to subjects exposed to invalid non-predictive cues. In contrast, valid cues reduced the proportion of omission errors for subjects trained in the predictive condition relative to subjects trained in the non-predictive condition. These results are congruent with those usually reported for humans and indicate that, in addition to the exogenous capture of attention promoted by both predictive and non-predictive peripheral cues, rats exposed to predictive cues engaged an additional slower process equivalent to human`s endogenous orienting of attention. To our knowledge, this is the first demonstration of an endogenous-like process of covert orienting of visual attention in rats.

A novel locus for split-hand/foot malformation associated with tibial hemimelia (SHFLD syndrome) maps to chromosome region 17p13.1-17p13.3

Split-hand/foot malformation (SHFM) associated with aplasia of long bones, SHFLD syndrome or Tibial hemimelia-ectrodactyly syndrome is a rare condition with autosomal dominant inheritance, reduced penetrance and an incidence estimated to be about 1 in 1,000,000 liveborns. To date, three chromosomal regions have been reported as strong candidates for harboring SHFLD syndrome genes: 1q42.2-q43, 6q14.1 and 2q14.2. We characterized the phenotype of nine affected individuals from a large family with the aim of mapping the causative gene. Among the nine affected patients, four had only SHFM of the hands and no tibial defects, three had both defects and two had only unilateral tibial hemimelia. In keeping with previous publications of this and other families, there was clear evidence of both variable expression and incomplete penetrance, the latter bearing hallmarks of anticipation. Segregation analysis and multipoint Lod scores calculations (maximum Lod score of 5.03 using the LINKMAP software) using all potentially informative family members, both affected and unaffected, identified the chromosomal region 17p13.1-17p13.3 as the best and only candidate for harboring a novel mutated gene responsible for the syndrome in this family. The candidate gene CRK located within this region was sequenced but no pathogenic mutation was detected.

Differential regulation of FGF-2 in neurons and reactive astrocytes of axotomized rat hypoglossal nucleus. A possible therapeutic target for neuroprotection in peripheral nerve pathology

Despite the favorable treatment of cranial nerve neuropathology in adulthood, some cases are resistant to therapy leading to permanent functional impairments In many cases, suitable treatment is problematic as the therapeutic target remains unknown Basic fibroblast growth factor (bFGF, FGF 2) is involved in neuronal maintenance and wound repair following nervous system lesions It is one of few neurotrophic molecules acting in autocrine, paracrine and intracrine fashions depending upon specific circumstances Peripheral cranial somatic motor neurons, i e hypoglossal (XII) neurons, may offer a unique opportunity to study cellular FGF 2 mechanisms as the molecule is present in the cytoplasm of neurons and in the nuclei of astrocytes of the central nervous system FGF-2 may trigger differential actions during development, maintenance and lesion of XII neurons because axotomy of those cells leads to cell death during neonatal ages, but not in adult life Moreover, the modulatory effects of astroglial FGF 2 and the Ca+2 binding protein S100 beta have been postulated in paracrine mechanisms after neuronal lesions In our study, adult Wistar rats received a unilateral crush or transection (with amputation of stumps) of XII nerve, and were sacrificed after 72 h or 11 days Brains were processed for immunohistochemical localization of neurofilaments (NF), with or without counterstaining for Nissl substance, ghat fibrillary acidic protein (GFAP, as a marker of astrocytes), S100 beta and FGF-2 The number of Nissl positive neurons of axotomized XII nucleus did not differ from controls The NF immunoreactivity increased in the perikarya and decreased in the neuropil of axotomized XII neurons 11 days after nerve crush or transection An astrocytic reaction was seen in the ipsilateral XII nucleus of the crushed or transected animals 72 h and 11 days after the surgery The nerve lesions did not change the number of FGF-2 neurons in the ipsilateral XII nucleus, however, the nerve transection increased the number of FGF-2 ghat profiles by 72 h and 11 days Microdensitometric image analysis revealed a short lasting decrease in the intensity of FGF 2 immunoreactivity in axotomized XII neurons by 72 h after nerve crush or transection and also an elevation of FGF-2 in the ipsilateral of ghat nuclei by 72h and 11 days after the two lesions S100 beta decreased in astrocytes of 11-day transected XII nucleus The two-color immunoperoxidase for the simultaneous detection of the GFAP/FGF-2 indicated FGF-2 upregulation in the nuclei of reactive astrocytes of the lesioned XII nucleus Astroglial FGF-2 may exert paracrine trophic actions in mature axotomized XII neurons and might represent a therapeutic target for neuroprotection in peripheral nerve pathology (C) 2009 Elsevier GmbH All rights reserved

Hemiparkinsonian rats rotate toward the side with the weaker dopaminergic neurotransmission

Rats with unilateral lesion of the substantia nigra pars compacta (SNpc) have been used as a model of Parkinson`s disease. Depending on the lesion protocol and on the drug challenge, these rats rotate in opposite directions. The aim of the present study was to propose a model to explain how critical factors determine the direction of these turns. Unilateral lesion of the SNpc was induced with 6-hydroxydopamine (6-OHDA) or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Separate analysis showed that neither the type of neurotoxin nor the site of lesion along the nigrostriatal. pathway was able to predict the direction of the turns these rats made after they were challenged with apomorphine. However, the combination of these two factors determined the magnitude of the lesion estimated by tyrosine-hydroxylase immunohistochemistry and HPLC-ED measurement of striatal dopamine. Very small lesions did Dot cause turns, medium-size lesions caused ipsiversive turns, and large lesions caused contraversive turns. Large-size SNpc lesions resulted in an increased binding of [H-3] raclopride to D2 receptors, while medium-size lesions reduced the binding of [H-3]SCH-23390 D1 receptors in the ipsilateral striatum. These results are coherent with the model proposing that after challenged with a dopamine receptor agonist, unilaterally SNpc-lesioned rats rotate toward the side with the weaker activation of dopamine receptors. This activation is weaker on the lesioned side in animals with small SNpc lesions due to the loss of dopamine, but stronger in animals with large lesions due to dopamine receptor supersensitivity. (C) 2008 Elsevier B.V. All rights reserved.

Morphometric analysis of the AMPA-type neurons in the Deiters vestibular complex of the chick brain

Chicken (Gallus gallus) brains were used to investigate the typology and the immunolabel pattern for the subunits composing the AMPA-type glutamate receptors (GluR) of hindbrain neurons of the dorsal (dND) and ventral nuclei (vND) of the Deiter`s vestibular complex (CD), which is the avian correspondent of the lateral vestibular nucleus (LVN) of mammals. Our results revealed that neurons of both divisions were poor in GluR1. The vND, the GluR2/3+ and GluR4+ label presented no area or neuronal size preference, although most neurons were around 75%. The dND neurons expressing GluR2/3 are primarily around 85%, medium to large-sized 85%, and predominantly 60% located in the medial portion of the rostral pole and in the lateral portion of the caudal pole. The majority of dND neurons containing GluR4 are also around 75%, larger (70% are large and giant), exhibiting a distribution that seems to be complementary to that of GluR2/3+ neurons. This distinct arrangement indicates functional differences into and between the DC nuclei, also signaling that such variation could be attributed to the diverse nature of the subunit composition of the GluRs. Discussion addresses the morphological and functional correlation of the avian DC with the LVN of mammals in addition to the high morphological correspondence, To include these data into the modern comparative approach we propose to adopt a similar nomenclature for the avian divisions dND and vND that could be referred as dLVN and vLVN. (C) 2008 Elsevier B.V. All rights reserved.

Retinal removal up-regulates cannabinoid CB1 receptors in the chick optic tectum

The endocannabinoid system has been implicated in several neurobiological processes, including neurodegeneration and neuro protection. The aim of this study was to evaluate the effects of unilateral retinal ablation on the expression of the cannabinoid receptor subtype 1 (CB1) at both protein and mRNA levels in the optic tectum of the adult chick brain. After different survival times postlesion (2-30 days), the chick brains were subjected to immunohistochemical, immunoblotting, and real-time PCR procedures to evaluate CB1 expression. TUNEL and Fluoro-Jade B were used to verify the possible occurrence of cell death, and immunostaining for the microtubule-associated protein MAP-2 was performed to verify possible dendritic remodeling after lesions. No cell death could be observed in the deafferented tectum, at least up to 30 days postlesion, although Fluoro-Jade B could reveal degenerating axons and terminals. Retinal ablation seems to generate an increase of CB1 protein in the optic tectum and other retinorecipient visual areas, which paralleled an increase in MAP-2 staining. On the other hand, CB, mRNA levels were not changed after retinal ablation. Our results reveal that CB, expression in visual structures of the adult chick brain may be negatively regulated by the retinal innervation. The increase of CB1 receptor expression observed after retinal removal indicates that these receptors are not presynaptic in retinal axons projecting to the tectum and suggests a role of the cannabinoid system in plasticity processes ensuing after lesions. (c) 2008 Wiley-Liss, Inc.