Biomechanical analysis of an interference screw and a novel twist lock screw design for bone graft fixation.

BACKGROUND: Malpositioning of an anterior cruciate ligament graft during reconstruction can occur during screw fixation. The purpose of this study is to compare the fixation biomechanics of a conventional interference screw with a novel Twist Lock Screw, a rectangular shaped locking screw that is designed to address limitations of graft positioning and tensioning. METHODS: Synthetic bone (10, 15, 20lb per cubic foot) were used simulating soft, moderate, and dense cancellous bone. Screw push-out and graft push-out tests were performed using conventional and twist lock screws. Maximum load and torque of insertion were measured. FINDINGS: Max load measured in screw push out with twist lock screw was 64%, 60%, 57% of that measured with conventional screw in soft, moderate and dense material, respectively. Twist lock max load was 78% and 82% of that with conventional screw in soft and moderate densities. In the highest bone density, max loads were comparable in the two systems. Torque of insertion with twist lock was significantly lower than with conventional interference screw. INTERPRETATION: Based on geometric consideration, the twist lock screw is expected to have 35% the holding power of a cylindrical screw. Yet, results indicate that holding power was greater than theoretical consideration, possibly due to lower friction and lower preloaded force. During graft push out in the densest material, comparable max loads were achieved with both systems, suggesting that fixation of higher density bone, which is observed in young athletes that require reconstruction, can be achieved with the twist lock screw.

Porous structure of ion exchange membranes investigated by various techniques.

A comparative review of various techniques is provided: mercury intrusion porosimetry, nitrogen sorption porosimetry, differential scanning calorimetry (DSC)-based thermoporosimetry, and standard contact porosimetry (SCP), which allows determining pore volume distribution versus pore radius/water binding energy in ion-exchange membranes (IEMs). IEMs in the swollen state have a labile structure involving micro-, meso- and macropores, whose size is a function of the external water vapor pressure. For such materials, the most appropriate methods for quantifying their porosity are DSC and SCP. Especially significant information is given by the SCP method allowing measuring porosimetric curves in a very large pore size range from 1 to 105nm. Experimental results of water distribution in homogeneous and heterogeneous commercial and modified IEMs are presented. The effect of various factors on water distribution is reviewed, i.e. nature of polymeric matrix and functional groups, method for membrane preparation, membrane ageing. A special attention is given to the effect of membrane modification by embedding nanoparticles in their structure. The porosimetric curves are considered along with the results of electrochemical characterization involving the measurements of membrane conductivity, as well as diffusion and electroosmotic permeability. It is shown that addition of nanoparticles may lead to either increase or decrease of water content in IEMs, different ranges of pore size being affected. Hybrid membranes modified with hydrated zirconium dioxide exhibit much higher permselectivity in comparison with the pristine membranes. The diversity of the responses of membrane properties to their modification allows for formation of membranes suitable for fuel cells, electrodialysis or other applications.

Ameloblastic fibroma in an alpine chamois (Rupicapra rupicapra).

Spontaneous odontogenic tumors are neoplasms characterized by a mixed odontogenic ectomesenchymal and odontogenic epithelial origin; they are rare in both humans and animals. A 3-year-old male Alpine Chamois (Rupicapra rupicapra) was found dead in north-west Italy, and was referred for the necropsy to the Department of Veterinary Sciences of the University of Turin (Italy). At the external examination a 10 × 8 cm, exophytic, red-pink, smooth, firm and ulcerated mass was observed on the inferior lip. Histologically the tumor was characterized by spindle shaped cells arranged in bundles in an abundant hyaline matrix. Multifocal and rare chords of odontogenic epithelium mixed with rare melanocytes that penetrate the neoplasia were visible. Immunohistochemistry showed a clear cytokeratin positivity of epithelial clusters. Macroscopical, histological and immunohistochemical findings were consistent with a diagnosis of locally infiltrative ameloblastic fibroma. To our best knowledge, this is the first report of this tumor in a wild ungulate and in Alpine Chamois.

Trends in biological joint resurfacing.

The treatment of osteochondral lesions and osteoarthritis remains an ongoing clinical challenge in orthopaedics. This review examines the current research in the fields of cartilage regeneration, osteochondral defect treatment, and biological joint resurfacing, and reports on the results of clinical and pre-clinical studies. We also report on novel treatment strategies and discuss their potential promise or pitfalls. Current focus involves the use of a scaffold providing mechanical support with the addition of chondrocytes or mesenchymal stem cells (MSCs), or the use of cell homing to differentiate the organism's own endogenous cell sources into cartilage. This method is usually performed with scaffolds that have been coated with a chemotactic agent or with structures that support the sustained release of growth factors or other chondroinductive agents. We also discuss unique methods and designs for cell homing and scaffold production, and improvements in biological joint resurfacing. There have been a number of exciting new studies and techniques developed that aim to repair or restore osteochondral lesions and to treat larger defects or the entire articular surface. The concept of a biological total joint replacement appears to have much potential. Cite this article: Bone Joint Res 2013;2:193-9.

Utilidad de Levosimendán en insuficiencia cardíaca aguda y su efecto sobre la función renal / No disponible

No disponible

Comparison of two PCR protocols for the detection of Neospora caninum DNA in rodents.

The objective of the present study was, due to increasing interest in the epidemiological role of small mammals as potential reservoir of Neospora caninum, to compare two different PCR protocols for the diagnosis of N. caninum in rodents. We tested tissue samples from 50 house mice (Mus musculus), 50 rats (Rattus norvegicus) and 35 field mice (Apodemus sylvaticus). Two different PCR protocols based on primer pairs, Np4-Np7 and Np6plus-Np21plus, were used for diagnosis on these samples. While there were not mismatches between the results of both PCR from rats or field mice, 49 out of 50 samples from house mice gave positive results with Np4-Np7 primer set. However after cloning and sequencing the PCR products, only six of these were confirmed to be N. caninum, while all the other 43 amplicons matched with house mice DNA sequence from clone RP23-14F5 on chromosome 11 sequence. Our results evidence that Np4-Np7 PCR could not be reliable in diagnosis of N. caninum in rodents.

Variabilidad en la comprensión gramatical en el envejecimiento normal / Variability in grammatical comprehension in normal aging

Para investigar la variabilidad interindividual –diversidad- en la comprensión de oraciones en el procesode envejecimiento normal, se obtuvieron cuatromedidas relativas al rendimiento en una tarea deverificación simple oración-dibujo para un total de196 personas mayores, de edades comprendidas entrelos 50 y los 80 años de edad, todos con estudios primarios (de uno a cinco años de escolaridad). Estasmedidas reflejan los aciertos obtenidos por cada personaen cuatro tipos de oraciones: una proposiciónordencanónico, una proposición-orden no canónico, dos proposiciones-orden canónico, dos proposiciones-orden no canónico.Los resultados descriptivos muestran que elnúmero de aciertos en la tarea disminuye a medidaque aumenta la edad, y que las oraciones con dosproposiciones son las más difíciles para los sujetos. Elanálisis de regresión de la edad sobre las medidas dela variabilidad -residuos estandarizados en valorabsoluto de las medidas originales- muestra: 1) que ladiversidad aumenta de forma lineal a medida queaumenta la edad en los tres primeros tipos de oraciones;y 2) que en las oraciones más difíciles (dos proposiciones – orden no canónico) la variabilidadaumenta hasta los 65-66 años, pero disminuye a partirde aquí, ajustándose así a una función cuadráticacon forma de U invertida. Se discuten las implicacionesde estos resultados en relación con otros estudiossobre la comprensión de oraciones en el procesode envejecimiento normal

To investigate the interindividual variability–diversity- in sentence comprehension in normalaging, four measures related to performance in asimple sentence-picture verification task wereobtained for 196 persons, ranging from 50 to 80years old, all with a primary level of education(from one to five years of scholarship). Thesemeasures reflect the number of correct responsesobtained by each person in four type of sentences:one proposition –canonical order; one proposition–noncanonical order, two propositions–canonical order, two proposition– noncanonicalorder.Descriptive results showed that the number ofcorrect responses in the task decreases as the ageincrease, and also that the sentences with twopropositions were the most difficult ones for thesubjects. The regression analysis of age over thevariability measures –absolute standarized residualsof the original indexes- showed that: (1) therewas an linear increment of diversity in the firstthree types of sentences as age increases; and (2)the variability increases until 65-66 years in themost difficult sentences (two propositions – noncanonicalorder), but decreases from that point,fitting to a cuadratic function with an inverted Ushape.The implications of these results are discussedwith respect to other studies on sentence comprehension in normal aging (AU)

[MRI findings in iliotibial band friction syndrome: a report of two cases]. / Hallazgos en resonancia magnética en el síndrome de fricción de la banda iliotibial. A propósito de dos casos.

We present the magnetic resonance imaging (MRI) findings in two males clinically diagnosed with iliotibial band friction syndrome (IBFS), a frequent cause of pain in the lateral compartment of the knee. Coronal T2-weighted images with fat saturation show an ill-defined area of high signal intensity in the soft tissues situated immediately below the iliotibial band lateral to the external condyle of the femur. No thickening of the iliotibial band or changes in its signal intensity were observed. Osseous edema and subchondral osseous erosion in the external condyle of the femur were observed in both cases. Pain in the lateral compartment of the knee might be due to multiple causes that should be included in the differential diagnosis and MRI can play a significant role in reaching the definitive diagnosis.

Hallazgos en resonancia magnética en el síndrome de fricción de la banda iliotibial. A propósito de dos casos / MRI findings in iliotibial band friction syndrome: a report of two cases

Presentamos los hallazgos realizados en la resonancia magnética (RM) de dos varones diagnosticados clínicamente de síndrome de fricción de la banda iliotibial (SFBIT), una causa frecuente de dolor en el compartimento lateral de la rodilla. En las imágenes coronales potenciadas en T2 con saturación de la grasa se muestra un área mal definida de alta intensidad de señal en el tejido de partes blandas situado en el plano inmediatamente en profundidad a la banda iliotibial (BIT), lateral al cóndilo femoral externo. La BIT no aparece engrosada ni se observan alteraciones en la intensidad de señal. Se observa en ambos casos un edema óseo y erosión ósea subcondral en el cóndilo femoral externo. El dolor en el compartimento lateral de la rodilla puede deberse a múltiples causas que deben incluirse en el diagnóstico diferencial, por lo que la RM tiene un importante papel para llegar a un diagnóstico definitivo (AU)

We present the magnetic resonance imaging (MRI) findings in two males clinically diagnosed with iliotibial band friction syndrome (IBFS), a frequent cause of pain in the lateral compartment of the knee. Coronal T2-weighted images with fat saturation show an ill-defined area of high signal intensity in the soft tissues situated immediately below the iliotibial band lateral to the external condyle of the femur. No thickening of the iliotibial band or changes in its signal intensity were observed. Osseous edema and subchondral osseous erosion in the external condyle of the femur were observed in both cases. Pain in the lateral compartment of the knee might be due to multiple causes that should be included in the differential diagnosis and MRI can play a significant role in reaching the definitive diagnosis (AU)

Evidence of Neospora caninum DNA in wild rodents.

Seventy-five house mice (Mus musculus), 103 rats (Rattus norvegicus) and 55 field mice (Apodemus sylvaticus) from North-West Italy were PCR analysed for Neospora caninum infection. Brain, kidney and muscle tissues collected from the above mentioned animals were tested by PCR using Np6 and Np21 primers. The brain tissue from 2 house mice and 2 rats, the kidney from 4 rats, 1 house mouse and 1 field mouse and muscle from 10 rats, 8 house mice and 1 field mouse were tested positive for N. caninum. Sequencing showed a 96-97% identity of PCR products with N. caninum NC1 sequence. Our findings support previous report on house mouse and rat, and for the first time, provides the evidence of the infection also in field mice. Based on our data, it could be hypothesized that mice can act as a reservoir of N. caninum, and they can play a role in maintaining/spreading N. caninum infection also in the sylvatic cycle. The possibility that dogs could be infected by eating infected house mice suggests new opportunities for N. caninum prophylaxis and control.

[Sarcoidosis with systemic involvement: a report of two cases]. / Sarcoidosis con afectación sistémica. A propósito de dos casos.

Sarcoidosis is a multisystemic granulomatose disease of unknown origin that most often affects the lung parenchyma and the mediastinal lymph nodes. Although less common, involvement of the abdominal organs and the central nervous is also possible. We present the radiological findings observed in two patients diagnosed with sarcoidosis with systemic involvement. In one case, the disease affected the lung, spleen, mediastinal and abdominal lymph nodes, whereas in the other case it affected the lung, spleen, abdominal lymph nodes and central nervous system. The aim of this report is to review the radiologic manifestations of this disease.

Sarcoidosis con afectación sistémica. A propósito de dos casos / Sarcoidosis with systemic involvement. A report of two cases

La sarcoidosis es una enfermedad granulomatosa multisistémica de etiología desconocida que afecta con mayor frecuencia al parénquima pulmonar y a los ganglios linfáticos mediastínicos. Aunque menos frecuente, la afectación de órganos abdominales y del sistema nervioso central también es posible. Presentamos los hallazgos radiológicos observados en dos pacientes diagnosticados de sarcoidosis con afectación sistémica, en uno de ellos la enfermedad afecta a pulmón, bazo, ganglios linfáticos mediastínicos y abdominales y en el otro a pulmón, bazo, ganglios linfáticos abdominales y sistema nervioso central. Nuestro objetivo es revisar las manifestaciones radiológicas de esta enfermedad

Sarcoidosis is a multisystemic granulomatose disease of unknown origin that most often affects the lung parenchyma and the mediastinal lymph nodes. Although less common, involvement of the abdominal organs and the central nervous is also possible. We present the radiological findings observed in two patients diagnosed with sarcoidosis with systemic involvement. In one case, the disease affected the lung, spleen, mediastinal and abdominal lymph nodes, whereas in the other case it affected the lung, spleen, abdominal lymph nodes and central nervous system. The aim of this report is to review the radiologic manifestations of this disease

[Diagnosis of thoracic outlet syndrome by angio-MRI]. / Diagnóstico por angiorresonancia magnética del síndrome del estrecho torácico superior.

OBJECTIVE: To evaluate the sequences and maneuvers recommended for the study of the thoracic outlet syndrome (TOS) and the usefulness of magnetic resonance imaging (MRI) in demonstrating its etiology. MATERIAL AND METHODS: We present a study of eight patients with clinical presentation suggestive of TOS. All underwent MRI, gadolinium-enhanced angio-MRI with the arms extended along the body and with postural maneuvers of abduction and elevation of the arms, plain-film chest x-rays, and digital angiography. The anatomic characteristics of the superior aperture of the thorax were analyzed on both sides before and during postural maneuvering. Likewise, the permeability of the vessels and integrity of the brachial plexus was studied. RESULTS: In two cases, angio-MRI demonstrated thrombosis, of the subclavian artery in one case and of the subclavian vein in the other, caused by a cervical rib, which was confirmed at plain-film chest x-ray. In one case, angio-MRI demonstrated stenosis of the subclavian artery on abduction, secondary to hypertrophy of the anterior scalene muscle, and digital angiography showed the same findings. In two cases, angio-MRI showed vascular thrombosis, arterial in one case and venous in the other, without evidence of anatomic anomalies; these findings were confirmed at digital angiography. In two cases, no pathological findings were observed at MRI, angio-MRI, or digital angiography. In one case, MRI showed the presence of a cervical rib without vascular repercussions. CONCLUSION: Gadolinium-enhanced angio-MRI is useful in the evaluation of TOS. It is important to examine patients at rest and during different postural maneuvers. In many cases it is possible to determine the cause of vascular compression.

Diagnóstico por angiorresonancia magnética del síndrome del estrecho torácico superior / Diagnosis of thoracic outlet syndrome by angio-MRI

Objetivo. Valorar las secuencias y las maniobras recomendadas para el estudio del síndrome del estrecho torácico superior (SETS) y la utilidad de la resonancia magnética (RM) a la hora de demostrar su etiología. Material y método. Presentamos un estudio de 8 pacientes con clínica sugerente de SETS. En todos ellos se realizó estudio anatómico de RM, angio-RM con gadolinio, con los brazos extendidos a lo largo del cuerpo y con maniobras posturales de abducción y elevación de los brazos, radiografía de tórax y angiografía digital. Se analizaron las características anatómicas del estrecho torácico superior bilateralmente antes y durante las maniobras posturales. Así mismo, se estudió la permeabilidad de los vasos y la integridad del plexo braquial. Resultados. En dos casos se demostró trombosis de la arteria y vena subclavias respectivamente producida por una costilla cervical, confirmada en la radiografía de tórax. En una paciente se demostró estenosis de la arteria subclavia con maniobra de abducción secundaria a hipertrofia del músculo escaleno anterior; la angiografía digital demostró los mismos hallazgos. En dos casos la angio-RM mostró trombosis vascular, arterial en un caso y venosa en otro, sin evidencia de anomalías anatómicas, este hallazgo se confirmó en el estudio de angiografía digital. En dos pacientes la RM, angio-RM y angiografía digital no mostraron hallazgos patológicos. En un caso la RM puso de manifiesto la presencia de una costilla cervical sin repercusión vascular. Conclusión. La angio-RM con gadolinio es útil para valorar el SETS. Es importante evaluar los pacientes en reposo y con maniobras posturales, pudiendo en muchos casos demostrar la causa responsable de la compresión vascular

Objective. To evaluate the sequences and maneuvers recommended for the study of the thoracic outlet syndrome (TOS) and the usefulness of magnetic resonance imaging (MRI) in demonstrating its etiology. Material and methods. We present a study of eight patients with clinical presentation suggestive of TOS. All underwent MRI, gadolinium-enhanced angio-MRI with the arms extended along the body and with postural maneuvers of abduction and elevation of the arms, plain-film chest x-rays, and digital angiography. The anatomic characteristics of the superior aperture of the thorax were analyzed on both sides before and during postural maneuvering. Likewise, the permeability of the vessels and integrity of the brachial plexus was studied. Results. In two cases, angio-MRI demonstrated thrombosis, of the subclavian artery in one case and of the subclavian vein in the other, caused by a cervical rib, which was confirmed at plain-film chest x-ray. In one case, angio-MRI demonstrated stenosis of the subclavian artery on abduction, secondary to hypertrophy of the anterior scalene muscle, and digital angiography showed the same findings. In two cases, angio-MRI showed vascular thrombosis, arterial in one case and venous in the other, without evidence of anatomic anomalies; these findings were confirmed at digital angiography. In two cases, no pathological findings were observed at MRI, angio-MRI, or digital angiography. In one case, MRI showed the presence of a cervical rib without vascular repercussions. Conclusion. Gadolinium-enhanced angio-MRI is useful in the evaluation of TOS. It is important to examine patients at rest and during different postural maneuvers. In many cases it is possible to determine the cause of vascular compression

[A comparative study of pragmatic language disorders and autism spectrum disorders using magnetoencephalography]. / Estudio comparativo mediante magnetoencefalografíade los trastornos del lenguaje pragmáticoy los trastornos del espectro autista.

INTRODUCTION: Pragmatics refers to the social use of language; its precursors are already present during the process of maturing, during the preverbal stage, and become manifest when the child starts to point and to share his or her attention with another person. In cases of specific language impairment (SLI) and autism spectrum disorders (ASD) it can be altered to varying degrees. PATIENTS AND METHODS: Due to the difficulties involved in diagnosis from a clinical point of view, we carried out a study by means of magnetoencephalography (MEG) on a series of 11 patients who had SLI and another series of 9 patients with ASD, in order to determine whether MEG is capable of distinguishing these diagnoses. RESULTS: Patients with SLI displayed pathological activity in the frontal and middle temporal regions of both hemispheres. Patients with ASD showed pathological activity in the perisylvian area. Expressive-receptive SLI with pragmatic language disorder showed pathological activity that was similar to that seen in autism. CONCLUSION: MEG can be used to distinguish between SLI and ASD by studying the epileptiform activity that occurs in pervasive developmental disorders. MEG helps us to understand the continuum that exists between SLI or expressive-receptive SLI and autism.

[The neurobiological foundations of learning disabilities]. / Bases neurobiológicas de las dificultades de aprendizaje.

INTRODUCTION: Learning disabilities constitute a heterogeneous group of disorders that involve significant alterations in different cognitive domains (acquisition and use of language, reasoning, mathematical skills, visuospatial abilities, and so forth) that are not accounted for by a low level of intelligence, inadequate sociocultural development or lack of academic opportunities. They result from an alteration in basic psychological processes, developmentally linked to an alteration in the central nervous system. Current functional neuroimaging techniques have made it possible to develop a new type of approach to the neurofunctional foundations underlying these disorders, especially with regard to difficulties in the realm of reading/ writing (developmental dyslexia) and attention deficit hyperactivity disorder (ADHD), which have their highest incidence among the infantile population of school-age children. DEVELOPMENT: Neuroimaging studies have revealed a pattern of atypical activity in both kinds of disorders. In the case of dyslexia, alterations have been observed in the perisylvian circuits that underlie the mechanisms involved in reading skills. Studies into ADHD suggest a fronto-striatal dysfunction linked to the difficulties encountered to achieve inhibitory control, as well as alterations in the inferior parietal and posterior temporal cortex. CONCLUSIONS: Functional neuroimaging studies have shown that the clinical manifestations of these disorders are not only due to a dysfunction in specific areas of the brain, but also to alterations in the pattern of connectivity.

Estudio comparativo mediante magnetoencefalografía de los trastornos del lenguaje pragmático y los trastornos del espectro autista / A comparative study of pragmatic language disorders and autism spectrum disorders using magnetoencephalography

Introducción. La pragmática es el uso social del lenguaje;sus precursores ya están presentes durante el proceso de maduración,durante la etapa preverbal, y se manifiestan cuando el niño empiezaa señalar y a compartir su atención con otra persona. Éstapuede estar alterada en los trastornos específicos del lenguaje (TEL)y en los trastornos del espectro autista (TEA). Pacientes y métodos.Debido a las dificultades diagnósticas desde el punto de vista clínico,hemos realizado un estudio con magnetoencefalografía (MEG) auna serie de 11 pacientes que presentaban un TEL y otra serie de 9pacientes con un TEA, para comprobar si la MEG es capaz de distinguirestos diagnósticos. Resultados. Los pacientes con TEL presentanactividad patológica en las regiones frontales y temporal mediade ambos hemisferios. Los pacientes con TEA presentan actividadpatológica en la zona perisilviana. Los TEL expresivo-receptivos contrastorno pragmático del lenguaje presentan una actividad patológicaparecida al autismo. Conclusión. La MEG, mediante el estudio dela actividad epileptiforme en los trastornos generalizados del desarrollo,permite distinguir los TEL con respecto a los TEA. La MEGayuda a entender el continuo entre TEL o TEL expresivo-receptivo yautismo

Introduction. Pragmatics refers to the social use of language; its precursors are already present during the processof maturing, during the preverbal stage, and become manifest when the child starts to point and to share his or her attentionwith another person. In cases of specific language impairment (SLI) and autism spectrum disorders (ASD) it can be altered tovarying degrees. Patients and methods. Due to the difficulties involved in diagnosis from a clinical point of view, we carriedout a study by means of magnetoencephalography (MEG) on a series of 11 patients who had SLI and another series of 9patients with ASD, in order to determine whether MEG is capable of distinguishing these diagnoses. Results. Patients with SLIdisplayed pathological activity in the frontal and middle temporal regions of both hemispheres. Patients with ASD showedpathological activity in the perisylvian area. Expressive-receptive SLI with pragmatic language disorder showed pathologicalactivity that was similar to that seen in autism. Conclusion. MEG can be used to distinguish between SLI and ASD by studyingthe epileptiform activity that occurs in pervasive developmental disorders. MEG helps us to understand the continuum thatexists between SLI or expressive-receptive SLI and autism

Bases neurobiológicas de las dificultades de aprendizaje / The neurobiological foundations of learning disabilities

Introducción. Las dificultades de aprendizaje comprendenun grupo heterogéneo de trastornos que implican alteracionessignificativas en diferentes dominios cognitivos (adquisición y usodel lenguaje, razonamiento, habilidades matemáticas, visuoespaciales,etc.) no justificadas por bajo nivel intelectual, desarrollosociocultural inadecuado o falta de oportunidades académicas.Éstas son el resultado de una alteración en los procesos psicológicosbásicos, evolutivamente ligados a una alteración del sistemanervioso central. Las actuales técnicas de neuroimagen funcionalhan permitido un nuevo tipo de acercamiento a las bases neurofuncionalesde estos trastornos, particularmente de las dificultades enel ámbito de la lectoescritura (dislexia evolutiva) y del trastornopor déficit de atención e hiperactividad (TDAH), los cuales tienenel mayor nivel de incidencia en la población escolar infantil. Desarrollo.Los estudios de neuroimagen han revelado un patrón de actividadatípico en ambos tipos de trastorno. En el caso de la dislexia,se han observado alteraciones de los circuitos perisilvianosque sustentan los mecanismos de lectura. Los estudios sobre TDAHsugieren una disfunción frontoestriatal ligada a las dificultadespara el control inhibitorio, así como alteraciones en la cortezatemporal posterior y parietal inferior. Conclusiones. Los estudiosde neuroimagen funcional revelan que las manifestaciones clínicasde estos trastornos no se deben sólo a la disfunción de áreas cerebralesconcretas, sino también a alteraciones en el patrón de conectividad

Introduction. Learning disabilities constitute a heterogeneous group of disorders that involve significant alterationsin different cognitive domains (acquisition and use of language, reasoning, mathematical skills, visuospatial abilities, and soforth) that are not accounted for by a low level of intelligence, inadequate sociocultural development or lack of academicopportunities. They result from an alteration in basic psychological processes, developmentally linked to an alteration in thecentral nervous system. Current functional neuroimaging techniques have made it possible to develop a new type of approachto the neurofunctional foundations underlying these disorders, especially with regard to difficulties in the realm of reading/writing (developmental dyslexia) and attention deficit hyperactivity disorder (ADHD), which have their highest incidenceamong the infantile population of school-age children. Development. Neuroimaging studies have revealed a pattern ofatypical activity in both kinds of disorders. In the case of dyslexia, alterations have been observed in the perisylvian circuitsthat underlie the mechanisms involved in reading skills. Studies into ADHD suggest a fronto-striatal dysfunction linked to thedifficulties encountered to achieve inhibitory control, as well as alterations in the inferior parietal and posterior temporalcortex. Conclusions. Functional neuroimaging studies have shown that the clinical manifestations of these disorders are notonly due to a dysfunction in specific areas of the brain, but also to alterations in the pattern of connectivity

Sonic hedgehog gene-enhanced tissue engineering for bone regeneration.

Improved methods of bone regeneration are needed in the craniofacial rehabilitation of patients with significant bone deficits secondary to tumor resection, congenital deformities, and prior to prosthetic dental reconstruction. In this study, a gene-enhanced tissue-engineering approach was used to assess bone regenerative capacity of Sonic hedgehog (Shh)-transduced gingival fibroblasts, mesenchymal stem cells, and fat-derived cells delivered to rabbit cranial bone defects in an alginate/collagen matrix. Human Shh cDNA isolated from fetal lung tissue was cloned into the replication-incompetent retroviral expression vector LNCX, in which the murine leukemia virus retroviral LTR drives expression of the neomycin-resistance gene. The rat beta-actin enhancer/promoter complex was engineered to drive expression of Shh. Reverse transcriptase-polymerase chain reaction analysis demonstrated that the transduced primary rabbit cell populations expressed Shh RNA. Shh protein secretion was confirmed by enzyme-linked immunosorbent assay (ELISA). Alginate/ type I collagen constructs containing 2 x 10(6) Shh-transduced cells were introduced into male New Zealand White rabbit calvarial defects (8 mm). A total of eight groups (N=6) were examined: unrestored empty defects, matrix alone, matrix plus the three cell populations transduced with both control and Shh expression vectors. The bone regenerative capacity of Shh gene enhanced cells was assessed grossly, radiographically and histologically at 6 and 12 weeks postimplantation. After 6 weeks, new full thickness bone was seen emanating directly from the alginate/collagen matrix in the Shh-transduced groups. Quantitative two-dimensional digital analysis of histological sections confirmed statistically significant (P<0.05) amounts of bone regeneration in all three Shh-enhanced groups compared to controls. Necropsy failed to demonstrate any evidence of treatment-related side effects. This is the first study to demonstrate that Shh delivery to bone defects, in this case through a novel gene-enhanced tissue-engineering approach, results in significant bone regeneration. This encourages further development of the Shh gene-enhanced tissue-engineering approach for bone regeneration.