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At least 595 records · Page 33Linked to original sources
PubMed1993

Comparison of the connectional properties of the two forelimb areas of the rat sensorimotor cortex: support for the presence of a premotor or supplementary motor cortical area.

The existence of multiple motor cortical areas that differ in some of their properties is well known in primates, but is less clear in the rat. The present study addressed this question from the point of view of connectional properties by comparing the afferent and efferent projections of the caudal forelimb area (CFA), considered to be the equivalent of the forelimb area of the primary motor cortex (MI), and a second forelimb motor representation, the rostral forelimb area (RFA). As a result of various tracing experiments (including double labeling), it was observed that CFA and RFA had reciprocal corticocortical connections characterized by preferential, asymmetrical, laminar distribution, indicating that RFA may occupy a different hierarchical level than CFA, according to criteria previously discussed in the visual cortex of primates. Furthermore, it was found that RFA, but not CFA, exhibited dense reciprocal connections with the insular cortex. With respect to their efferent projection to the basal ganglia, it was observed that CFA projected very densely to the lateral portion of the ipsilateral caudate putamen, whereas the contralateral projection was sparse and more restricted. The ipsilateral projection originating from RFA was slightly less dense than that from CFA, but it covered a larger portion of the caudate putamen (in the medial direction); the contralateral projection from RFA to the caudate putamen was of the same density and extent as the ipsilateral projection. The reciprocal thalamocortical and corticothalamic connections of RFA and CFA differed from each other in the sense that CFA was mainly interconnected with the ventrolateral thalamic nucleus, while RFA was mainly connected with the ventromedial thalamic nucleus. Altogether, these connectional differences, compared with the pattern of organization of the motor cortical areas in primates, suggest that RFA in the rat may well be an equivalent of the premotor or supplementary motor area. In contrast to the corticocortical, corticostriatal, and thalamocortical connections, RFA and CFA showed similar efferent projections to the subthalamic nucleus, substantia nigra, red nucleus, tectum, pontine nuclei, inferior olive, and spinal cord.

Afferent Pathways↗
PubMed1988

[Function of connectives in text-understanding].

This experiment was conducted to investigate the function of connectives in text comprehension. Twenty six subjects were instructed to read six texts, each containing several target sentences. Eighteen target sentences were provided, and each of the subjects was presented half of the target sentences in their original form, i.e., with a connective (Connective condition, C), and the other half, without a connective (No-connective condition, NC). After reading, subjects were asked to recall all the target sentences. In recall, all the sentences preceding the target sentence were presented as a cue. Recall rate was higher for the C condition than for the NC condition. The result indicated that connectives facilitate text comprehension. This effect was seen most clearly in three connective categories called jyunsetsu (e.g., causality), gyakusetsu (i.e., adversity), hosoku (i.e., supplement) in Japanese.

Adult↗
PubMed2000

Functional specificity of callosal connections in tree shrew striate cortex.

Although callosal connections have been shown to link extensive regions of primary visual cortex, the distribution of these connections with respect to the map of visual space and the map of orientation preference remains unclear. Here we combine optical imaging of intrinsic signals with injection of fluorescent microspheres to assess the functional specificity of callosal connections in the tree shrew. By imaging both hemispheres simultaneously while presenting a series of spatially restricted stimuli, we find that a substantial region of visual space is represented bilaterally. Each hemisphere includes a representation of the ipsilateral visual field that is highly compressed relative to that of the contralateral visual field and is most extensive in the lower visual field, where approximately 30(o) of central visual space are represented bilaterally. Callosal connections extend throughout the region of bilateral representation but terminate in a spatially restricted manner that links visuotopically corresponding sites in the two hemispheres. In contrast, callosal connections appear to terminate without regard for the map of orientation preference, showing little sign of the orientation-specific modular and axial specificity that is characteristic of long-range horizontal connections. By coordinating the activity in the two hemispheres in a way that preserves nearest neighbor relationships, callosal connections may best be viewed as elements of local circuits that operate within a single bilateral representation of visual space.

Animals↗
PubMed2000

Organization and connections of V1 in Monodelphis domestica.

We examined the internal organization and connections of the primary visual area, V1, in the South American marsupial Monodelphis domestica. Multiunit electrophysiological recording techniques were used to record from neurons at multiple sites. Receptive field location, size, progressions, and reversals were systematically examined to determine the visuotopic organization of V1 and its boundaries with adjacent visual areas. As in other mammals, a virtually complete representation of the visual hemifield was observed in V1, which was coextensive with a region of dense myelination. The vertical meridian was represented at the rostrolateral boundary of the field, the upper visual quadrant was represented caudolaterally, whereas the lower visual quadrant was represented rostromedially. Injections of fluorescent tracers into V1 revealed dense connections with cortex immediately adjacent to the rostrolateral boundary, in peristriate cortex (PS or V2). Connections were also consistently observed with a caudotemporal area (CT), entorhinal cortex (EC), and multimodal cortex (auditory/visual, A/V). These results demonstrate that M. domestica possess a highly differentiated neocortex with clear functional and architectonic cortical field boundaries, as well as discrete patterns of cortical connections. Some connections of V1 are similar to those observed in eutherian mammals, such as connections with V2 and extrastriate areas (e.g., CT), which suggests that there are general features of visual system organization that all mammals possess due to retention from a common ancestor. On the other hand, connections of V1 with EC and multimodal cortex may be a primitive feature of visual cortex that was lost in some lineages, may be a derived feature of marsupial neocortex, or may be a feature particular to mammals with small brains.

Animals↗
PubMed2001

Effect of focal and nonfocal cerebral lesions on functional connectivity studied with MR imaging.

BACKGROUND AND PURPOSE: Functional connectivity MR (fcMR) imaging is used to map regions of brain with synchronous, regional, slow fluctuations in cerebral blood flow. We tested the hypothesis that focal cerebral lesions do not eradicate expected functional connectivity. METHODS: Functional MR (fMR) and fcMR maps were acquired for 12 patients with focal cerebral tumors, cysts, arteriovenous malformations, or in one case, agenesis of the corpus callosum. Task activation secondary to text listening, finger tapping, and word generation was mapped by use of fMR imaging. Functional connectivity was measured by selecting "seed" voxels in brain regions showing activation (based on the fMR data) and cross correlating with every other voxel (based on data acquired while the subject performed no task). Concurrence of the fMR and fcMR maps was measured by comparing the location and number of voxels selected by both methods. RESULTS: Technically adequate fMR and fcMR maps were obtained for all patients. In patients with focal lesions, the fMR and fcMR maps correlated closely. The fcMR map generated for the patient with agenesis of the corpus callosum failed to reveal functional connectivity between blood flow in the left and right sensorimotor cortices and in the frontal lobe language regions. Nonetheless, synchrony between blood flow in the auditory cortices was preserved. On average, there was 40% concurrence between all fMR and fcMR maps. CONCLUSION: Patterns of functional connectivity remain intact in patients with focal cerebral lesions. Disruption of major neuronal networks, such as agenesis of the corpus callosum, may diminish the normal functional connectivity patterns. Therefore, functional connectivity in such patients cannot be fully demonstrated with fcMR imaging.

Agenesis of Corpus Callosum↗
PubMed2001

Rules of connectivity between geniculate cells and simple cells in cat primary visual cortex.

Hundreds of thalamic axons ramify within a column of cat visual cortex; yet each layer 4 neuron receives input from only a fraction of them. We have examined the specificity of these connections by recording simultaneously from layer 4 simple cells and cells in the lateral geniculate nucleus with spatially overlapping receptive fields (n = 221 cell pairs). Because of the precise retinotopic organization of visual cortex, the geniculate axons and simple-cell dendrites of these cell pairs should have overlapped within layer 4. Nevertheless, monosynaptic connections were identified in only 33% of all cases, as estimated by cross-correlation analysis. The visual responses of monosynaptically connected geniculate cells and simple cells were closely related. The probability of connection was greatest when a geniculate center overlapped a strong simple-cell subregion of the same sign (ON or OFF) near the center of the subregion. This probability was further increased when the time courses of the visual responses were similar. In addition, the connections were strongest when the simple-cell subregion and the geniculate center were matched in position, sign, and size. The rules of connectivity between geniculate afferents and simple cells resemble those found for retinal afferents to geniculate cells. The connections along the retinogeniculocortical pathway, therefore, show a precision that goes beyond simple retinotopy to include many other response properties, such as receptive-field sign, timing, subregion strength, and size. This specificity in wiring emphasizes the need for developmental mechanisms (presumably correlation-based) that can select among afferents that differ only slightly in their response properties.

Action Potentials↗
PubMedDate not supplied

Role of connectivity in immune and neural network models: memory development and aging.

In this paper we analyzed how connectivity (defined as number of connections between network elements) can affect the memory capacity of a network-based model of the Immune System (IS) and of a model of the Nervous System (NS) synaptic plasticity (BCM model). The key point is the concept of competition between the characteristic variables that represent the response of such systems to environmental stimuli: the clonal concentrations for the IS, and the neuron responses for the BCM model. The memory states of both systems are characterized by a high selectivity to specific input patterns, reflecting a similar behaviour of their development rules. This selectivity property of memory states can be controlled by changing the degree of the internal connectivity in each system. We can explain the changes occurring in IS memory states during lifespan as due to a reshaping of its internal connectivity. This assumption is in agreement with experimental observations, reporting an increase of IS memory cells during lifespan. The change of connectivity in the BCM model leads to the introduction of quasilocal variables governing the plasticity of groups of synaptic junctions. This could be interpreted as the result of a refinement of neuron internal mechanisms during development, or it could be seen as a different learning rule deriving from the original BCM theory. We argue that connectivity seems to play an important role in a large class of biological systems controlled by competition mechanisms. Moreover, changes in connectivity may lead to changes in memory properties during development and aging.

Aging↗
PubMed1991

A detailed model of the primary visual pathway in the cat: comparison of afferent excitatory and intracortical inhibitory connection schemes for orientation selectivity.

In order to arrive at a quantitative understanding of the dynamics of cortical neuronal networks, we simulated a detailed model of the primary visual pathway of the adult cat. This computer model comprises a 5 degrees x 5 degrees patch of the visual field at a retinal eccentricity of 4.5 degrees and includes 2048 ON- and OFF-center retinal beta-ganglion cells, 8192 geniculate X-cells, and 4096 simple cells in layer IV in area 17. The neurons are implemented as improved integrate-and-fire units. Cortical receptive fields are determined by the pattern of afferent convergence and by inhibitory intracortical connections. Orientation columns are implemented continuously with a realistic receptive field scatter and jitter in the preferred orientations. We first show that realistic ON-OFF-responses, orientation selectivity, velocity low-pass behaviour, null response, and responses to spot stimuli can be obtained with an appropriate alignment of geniculate neurons converging onto the cortical simple cell (Hubel and Wiesel, 1962) and in the absence of intracortical connections. However, the average receptive field elongation (length to width) required to obtain realistic orientation tuning is 4.0, much higher than the average observed elongation. This strongly argues for additional intracortical mechanisms sharpening orientation selectivity. In the second stage, we simulated five different inhibitory intracortical connection patterns (random, local, sparse-local, circular, and cross-orientation) in order to investigate the connection specificity necessary to achieve orientation tuning. Inhibitory connection schemes were superimposed onto Hubel and Wiesel-type receptive fields with an elongation of 1.78. Cross-orientation inhibition gave rise to different horizontal and vertical orientation tuning curves, something not observed experimentally. A combination of two inhibitory schemes, local and circular inhibition (a weak form of cross-orientation inhibition), is in good agreement with observed receptive field properties. The specificity required to establish these connections during development is low. We propose that orientation selectivity is caused by at least three different mechanisms ("eclectic" model): a weak afferent geniculate bias, broadly tuned cross-orientation inhibition, and some iso-orientation inhibition. The most surprising finding is that an isotropic connection scheme, circular inhibition, in which a cell inhibits all of its postsynaptic target cells at a distance of approximately 500 microns, enhances orientation tuning and leads to a significant directional bias. This is caused by the embedding of cortical cells within a columnar structure and does not depend on our specific assumptions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Partial anomalous pulmonary venous connection to the right side of the heart.

Partial anomalous pulmonary venous connection to the right side of the heart often complicates surgery for atrial septal defects. Between 1964 and 1987, 39 patients, ranging from 2 to 52 years old, underwent repair of partial anomalous pulmonary venous connection. At least one anomalous pulmonary vein arose from the right upper lobe in 38 patients and right middle lobe in 30 patients and connected to the superior vena cava in 28 patients and the right atrium only in 11 patients. An atrial septal defect was present in 32 patients (82%). Patients who had partial anomalous pulmonary venous connection to the superior vena cava-right atrium junction, the right atrium or both were treated by septal translocation (two patients) or patch redirection of the anomalous pulmonary venous flow to the left atrium through a native atrial septal defect (eight patients) or a surgically created atrial septal defect in two patients with intact atrial septum. For partial anomalous pulmonary venous connection to the high superior vena cava (27 patients), the superior vena cava was transected and oversewn above the anomalous veins. The anomalous pulmonary venous flow was redirected through the proximal superior vena cava into the left atrium across a sinus venous atrial septum defect (22 patients) or a surgically created atrial septal defect in five patients with intact atrial septum. The atrial septal defect was coapted to the intracardiac orifice of the superior vena cava, and the distal superior vena cava was anastomosed to the right atrial appendage. One 31-year-old woman with severe pulmonary hypertension died early and was the only death in the series. A technical error early in the series resulted in one symptomatic superior vena cava obstruction. Only one patient remains in sick sinus syndrome late. All patients remain well over long follow-up (1 to 24 years). Postoperative catheterization or echocardiography has revealed no intracardiac defects, pulmonary venous obstruction, or superior vena cava obstruction (except the one technical error). Correction of partial anomalous pulmonary venous connection should be individualized according to the site of connection of the anomalous pulmonary veins and the location of the atrial defect to minimize undesirable postoperative sequelae often associated with other methods of repair.

Adolescent↗
PubMed1983

Laminar organization of efferent connections of the prefrontal cortex in the dog.

The method of retrograde HRP transport was used to study the laminar organization of cortico-subcortical and cortico-cortical connections of the dog's prefrontal cortex (PFC). The neurons of deep cortical layers VI and V gave rise to cortico-subcortical connections, while cortico-cortical connections originated from layers II-VI. Among them, the main source of intracortical connections was layer III. Differences in the distribution of labeled cells in sublayers IIIa and IIIb seemed to depend on the length of connections, e.g., local and distal as well as ipsi- and contralateral connections. The neurons which are a source of both cortico-subcortical and cortico-cortical connections were located more superficially in the medial PFC fields. Such distribution of neurons seems to be related to the differences of cytoarchitectonic structure of the medial and lateral PFC surface. Most frequently the projective neurons were of a pyramidal type, although some fusiform and stellate types were occasionally found.

Animals↗
PubMed1994

Aggregation of beta A3-crystallin is independent of the specific sequence of the domain connecting peptide.

The beta- and gamma-crystallins are structural proteins whose high concentration and close packing are important in maintaining transparency of the eye lens. The beta gamma-crystallin superfamily includes proteins with similar core structures consisting of two compact domains linked by a short connecting peptide. In gamma-crystallins, the connecting peptide folds back on itself, allowing the amino and carboxyl domains to participate in close interactions. The beta-crystallin connecting peptide is extended so that dimerization of two beta-crystallin monomers is required for similar interdomain interactions. In order to examine the role of the sequence of the connecting peptide in determining the extended beta-crystallin conformation and hence their association into dimers, we have exchanged the 10 residues of the beta A3-crystallin connecting peptide with the 9-residue connecting peptide sequence of mouse gamma B-crystallin by site-directed mutagenesis. Unaltered and modified recombinant beta A3-crystallins were expressed in a baculovirus system and purified by sequential anion exchange chromatography and gel filtration. Integrity of the recombinant crystallins was confirmed by NH2-terminal sequence analysis, immunoblots, and CD spectrometry. Reconstitution of the mutant recombinant protein with crystallins from mouse lens soluble extract resulted in aggregates of identical size distribution as normal beta A3-crystallin. We conclude that the sequence of the connecting peptide is not critical for the association of beta A3-crystallin into dimers and higher order aggregates as had been postulated.

Amino Acid Sequence↗
PubMed1996

The role of activity in the development of long-range horizontal connections in area 17 of the ferret.

Horizontal connections in area 17 of adult cats and ferrets link cells with similar preferred orientations by a patchy network of projections extending several millimeters across the cortex. The maturation of orientation selectivity in ferret area 17 has been demonstrated previously by quantitative single-unit recording and optical imaging to begin at approximately postnatal days (P) 32-P36. We therefore made restricted injections of cholera toxin B-subunit (CTB) or CTB-gold into ferret area 17 at a series of developmental ages and statistically quantified the degree of clustering in plots of retrogradely labeled cells in tangential sections through layer III for comparison to the published values for orientation tuning at each age. At P21, horizontal connections within area 17 lacked patchiness entirely, although clear patches of labeled cells were present in extrastriate areas. By P27, significant clustering of horizontal connections within area 17 was present. A second phase of cluster refinement was observed to occur at approximately P34-P36, coinciding with the emergence of mature orientation tuning and maps. Continuous silencing of cortical action potentials by chronic tetrodotoxin infusion from P21 resulted in a spatially random distribution of retrogradely labeled cells at P34. In contrast, bilateral enucleation from P21 did not prevent the initial development of clustered horizontal connections. We conclude, based on our findings and those of others, that the anatomical specificity of long-range horizontal connections results from an activity-dependent process that initially can use spontaneous activity in the cortical and thalamic networks to establish crude periodic connections and later uses visual cues to refine these connections.

Animals↗
PubMed1997

Orientation selectivity and the arrangement of horizontal connections in tree shrew striate cortex.

Horizontal connections, formed primarily by the axon collaterals of pyramidal neurons in layer 2/3 of visual cortex, extend for millimeters parallel to the cortical surface and form patchy terminations. Previous studies have provided evidence that the patches formed by horizontal connections exhibit modular specificity, preferentially linking columns of neurons with similar response characteristics, such as preferred orientation. The issue of how these connections are distributed with respect to the topographic map of visual space, however, has not been resolved. Here we combine optical imaging of intrinsic signals with small extracellular injections of biocytin to assess quantitatively the specificity of horizontal connections with respect to both the map of orientation preference and the map of visual space in tree shrew V1. Our results indicate that horizontal connections outside a radius of 500 microm from the injection site exhibit not only modular specificity, but also specificity for axis of projection. Labeled axons extend for longer distances, and give off more terminal boutons, along an axis in the map of visual space that corresponds to the preferred orientation of the injection site. Inside of 500 microm, the pattern of connections is much less specific, with boutons found along every axis, contacting sites with a wide range of preferred orientations. The system of long-range horizontal connections can be summarized as preferentially linking neurons with co-oriented, co-axially aligned receptive fields. These observations suggest specific ways that horizontal circuits contribute to the response properties of layer 2/3 neurons and to mechanisms of visual perception.

Animals↗
PubMed1997

Topographic organization of medial pulvinar connections with the prefrontal cortex in the rhesus monkey.

The medial nucleus of the pulvinar complex (PM) has widespread connections with association cortex. We investigated the connections of the PM with the prefrontal cortex (PFC) in macaque monkeys, with tracers placed into the PM and the PFC, respectively. Injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) placed into the PM resulted in widespread anterograde terminal labeling in layers III and IV, and retrograde cellular labeling in layer VI of the PFC. Injections of tracers centered on the central/lateral PM resulted in labeling of dorsolateral and orbital regions, whereas injections centered on caudal, medial PM resulted in labeling of dorsomedial and medial PFC. Since injections of the PM included neighboring thalamic nuclei, retrograde tracers were placed into distinct cytoarchitectonic regions of the PFC and retrogradely labeled cells in the posterior thalamus were charted. The results of this series of tracer injections confirmed the results of thalamic injections. Injections placed into areas 8a, 12 (lateral and orbital), 45, 46 and 11, retrogradely labeled neurons in the central/lateral PM, while tracer injections placed into areas 9, 12 (lateral), 10 and 24, labeled medial PM. The connections of the PM with temporal, parietal, insular, and cingulate cortices were also examined. The central/lateral PM has reciprocal connections with posterior parietal areas 7a, 7ip, and 7b, insular cortex, caudal superior temporal sulcus (STS), caudal superior temporal gyrus (STG), and posterior cingulate, whereas medial PM is connected mainly with the anterior STS and STG, as well as the cingulate cortex and the amygdala. These connectional studies suggest that the central/ lateral and medial PM have divergent connections which may be the substrate for distinct functional circuits.

Animals↗
PubMed1997

Functional specificity of long-range intrinsic and interhemispheric connections in the visual cortex of strabismic cats.

The development of both long-range intracortical and interhemispheric connections depends on visual experience. Previous experiments showed that in strabismic but not in normal cats, clustered horizontal axon projections preferentially connect cell groups activated by the same eye. This indicates that there is selective stabilization of fibers between neurons exhibiting correlated activity. Extending these experiments, we investigated in strabismic cats: (1) whether tangential connections remain confined to columns of similar orientation preference within the subsystems of left and right eye domains; and (2) whether callosal connections also extend predominantly between neurons activated by the same eye and preferring similar orientations. To this end, we analyzed in strabismic cats the topographic relationships between orientation preference domains and both intrinsic and callosal connections of area 17. Red and green latex microspheres were injected into monocular iso-orientation domains identified by optical imaging of intrinsic signals. Additionally, domains sharing the ocular dominance and orientation preference of the neurons at the injection sites were visualized by 2-deoxyglucose (2-DG) autoradiography. Quantitative analysis revealed that 56% of the retrogradely labeled cells within the injected area 17 and 60% of the transcallosally labeled neurons were located in the 2-DG-labeled iso-orientation domains. This indicates: (1) that strabismus does not interfere with the tendency of long-range horizontal fibers to link predominantly neurons of similar orientation preference; and (2) that the selection mechanisms for the stabilization of callosal connections are similar to those that are responsible for the specification of the tangential intrinsic connections.

Animals↗
PubMed1998

Interhemispheric connections of somatosensory cortex in the flying fox.

The interhemispheric connections of somatosensory cortex in the gray-headed flying fox (Pteropus poliocephalus) were examined. Injections of anatomical tracers were placed into five electrophysiologically identified somatosensory areas: the primary somatosensory area (SI or area 3b), the anterior parietal areas 3a and 1/2, and the lateral somatosensory areas SII (the secondary somatosensory area) and PV (pairetal ventral area). In two animals, the hemisphere opposite to that containing the injection sites was explored electrophysiologically to allow the details of the topography of interconnections to be assessed. Examination of the areal distribution of labeled cell bodies and/or axon terminals in cortex sectioned tangential to the pial surface revealed several consistent findings. First, the density of connections varied as a function of the body part representation injected. For example, the area 3b representation of the trunk and structures of the face are more densely interconnected than the representation of distal body parts (e.g., digit 1, D1). Second, callosal connections appear to be both matched and mismatched to the body part representations injected in the opposite hemisphere. For example, an injection of retrograde tracer into the trunk representation of area 3b revealed connections from the trunk representation in the opposite hemisphere, as well as from shoulder and forelimb/wing representations. Third, the same body part is differentially connected in different fields via the corpus callosum. For example, the D1 representation in area 3b in one hemisphere had no connections with the area 3b D1 representation in the opposite hemisphere, whereas the D1 representation in area 1/2 had relatively dense reciprocal connections with area 1/2 in the opposite hemisphere. Finally, there are callosal projections to fields other than the homotopic, contralateral field. For example, the D1 representation in area 1/2 projects to contralateral area 1/2, and also to area 3b and SII.

Animals↗
PubMed2002

Ultrastructural connective tissue aberrations in patients with intracranial aneurysms.

BACKGROUND AND PURPOSE: An unknown connective tissue defect might predispose for the development and rupture of intracranial aneurysms in some patients. This study of connective tissue samples of a series of patients with intracranial aneurysms investigates the morphology of the extracellular matrix with methods that are currently used in the routine diagnosis of inherited connective tissue disorders. METHODS: Skin biopsies from 21 patients with intracranial aneurysms, many with multiple aneurysms, were studied by electron microscopy. None of the patients included in this study showed clinical signs of a known connective tissue disorder. RESULTS: In 7 patients (33%), we observed repetitive aberrations in the morphology of collagen fibrils and elastic fibers of the reticular dermis. The observed ultrastructural findings were somewhat similar to those typically observed in patients with Ehlers-Danlos syndrome (EDS) and in a subgroup of patients with spontaneous cervical artery dissections. The patterns of abnormalities fell into 2 classes: 4 patients displayed abnormalities that resembled those found in patients with EDS type III, and the electron microscopic findings in the skin biopsies from 3 patients resembled those of EDS type IV patients. The sequence of the COL3A1 gene from the patients with EDS type IV-like alterations of the connective tissue morphology was analyzed. No mutation was detected. CONCLUSIONS: Connective tissue alterations were found in skin biopsies from a minority of patients with intracranial aneurysms. Electron microscopic investigation of skin biopsies from patients and their relatives might become valuable for clinical diagnostics, identification of persons at risk, and basic studies of the pathogenesis of this vascular disease.

Adult↗
PubMed2006

[Pulmonary arterial hypertension in connective tissue disease].

INTRODUCTION: Pulmonary arterial hypertension (PAH) is one of the most severe complications of connective tissue diseases. PAH is defined by mean arterial pulmonary pressure > 25 mmHg at rest (or 30 mmHg during exercise) during right heart catheterisation. STATE OF THE ART: About 10% of cases of PAH are related to connective tissue diseases. PAH may be observed in any of the connective tissue diseases; it is mostly encountered in systemic sclerosis (prevalence estimated to 8%), and is more frequent in the limited form of the disease with anticentromeres antibodies, in the presence of Raynaud's phenomenon, of antinuclear antibodies, decreased CO diffusion capacity, and during the perimenopausal period. Histopathological lesions are similar to that of idiopathic PAH (with plexogenic lesions being more rare); mutations have not been described. Venous thromboembolic disease (especially in lupus) and hypoxemia related to pulmonary fibrosis should be investigated. Screening for PAH is recommended in systemic sclerosis (by echocardiography every year and in case of dyspnea). Few clinical trials have been conducted specifically in PAH related to connective tissue diseases, therefore the treatment approach is similar to that of idiopathic PAH, with a poorer prognosis, including treatment with bosentan, epoprostenol and other prostacyclin analogs, and sildenafil. Immunosuppressive therapy may occasionally improve PAH in patients with systemic erythematosus lupus or mixed connective tissue disease. PERSPECTIVES: Respective indications of drugs and treatment associations need to be precised. CONCLUSION: The availability of efficacious treatments of PAH justifies its screening and early diagnosis in connective tissue diseases.

Antihypertensive Agents↗