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F Villarreal

Publications and source records attributed to F Villarreal.

5 recordsLinked to original sources
PubMed2000

Identification of G protein-coupled signaling pathways in cardiac fibroblasts: cross talk between G(q) and G(s).

Cardiac fibroblasts (CFs) are an important cellular component of myocardial responses to injury and to hypertrophic stimuli. We studied G protein-coupled receptors to understand how CFs integrate signals that activate G(q), G(s), and G(i). We predicted that the second messenger pathways present in CFs were distinct from those in cardiac myocytes and that unique signaling interactions existed in the CFs. ANG II, bradykinin, ATP, and UTP stimulated inositol phosphate (IP) production 2.2- to 7-fold. Each of these agonists elevated intracellular Ca(2+) concentration ([Ca(2+)](i)) via release from the intracellular Ca(2+) storage compartment. Endothelin-1 (ET-1), carbachol, and norepinephrine failed to increase either IP production or [Ca(2+)](i). Although agonists that activated IP and Ca(2+) transients had no effect on cAMP production when administered alone, these agents potentiated the beta(2)-adrenergic response two- to fourfold. Hormones known to inhibit adenylyl cyclase activity in cardiac myocytes, such as ET-1 and carbachol, failed to lower the beta-adrenergic response in fibroblasts. Order of potency and inhibitor data indicate that the functional receptor subtypes in these cells are beta(2), P2Y(2), and AT(1) for isoproterenol, ATP, and ANG II, respectively. We conclude that CFs express functional G protein-linked receptors that couple to G(q) and G(s), with little or no coupling to G(i). The expression of receptors and their coupling to G(q)- but not to G(i)-linked responses distinguishes the signaling in CFs from that in myocytes. Furthermore, agonists that activate G(q) in CFs potentiate stimulation of G(s), an example of signaling cross talk not observed in adult myocytes. These data suggest that G protein-mediated signaling in CFs is unique and may contribute to the specificity of hormone and drug action on individual cell types within the heart.

Adenosine Triphosphate↗
PubMed1988

Relation between transmural deformation and local myofiber direction in canine left ventricle.

To determine the relation between local myofiber anatomy and local deformation in the wall of the left ventricle, both three-dimensional transmural deformation and myofiber orientation were examined in the anterior free wall of seven canine left ventricles. Deformation was measured by imaging columns of implanted radiopaque markers with high-speed, biplane cineradiography (16 mm, 120 frames/sec). Hearts were fixed at end diastole and sectioned parallel to the local epicardial tangent plane to determine the transmural distribution of fiber directions at the site of strain measurement. The principal direction of deformation associated with the greatest shortening was compared with the local fiber direction in the outer (21 +/- 8% of the wall thickness from the epicardium) and inner (65 +/- 9%) halves of the wall. Although the fiber direction varied substantially with depth from the epicardium, the principal direction did not. In the outer half of the wall, fiber direction averaged -8 +/- 24 degrees, while the principal direction averaged -33 +/- 24 degrees from circumferential (counterclockwise angles are positive). In the inner half, fiber direction averaged 69 +/- 10 degrees, while the principal direction averaged -22 +/- 21 degrees. Therefore, while fiber and principal directions were not substantially different in the outer half, the greatest shortening occurred orthogonally to the fiber direction in the inner half. Normal and shear strains measured in a cardiac coordinate system (circumferential, longitudinal, and radial coordinates) were rotated (transformed) to "fiber" coordinates in both halves of the wall. In the outer half, normal strains observed in the fiber (-0.09 +/- 0.04) and cross-fiber (-0.04 +/- 0.04) directions were not significantly different (paired t test, p less than 0.05). In the inner half, more than twice as much strain occurred in the cross-fiber (-0.17 +/- 0.03) than in the fiber direction (-0.06 +/- 0.06). Moreover, the only shear strain that remained substantial after transformation was transverse shear in the plane of the fiber and radial coordinates. These results suggest that both reorientation and cross-sectional shape changes of myofibers or the interstitium may contribute to the large wall thickenings observed during contraction, particularly in the inner half of the ventricular wall.

Animals↗
PubMedDate not supplied

[Multiple cerebral tuberculomas].

INTRODUCTION: The tuberculosis is a disease that continues being important cause of morbidity and mortality at worldwide level. Its presentation as tuberculomas cerebral manifold at level of the central nervous system is little frequent in immunocompetent patients and can be confused with other etiology. CASE REPORT: An indigenous young man, immunocompetent consulted for history of headache, nausea, vomits, convulsions, double vision and hemiparesia left side, which in the cerebral tomography of revenue was showing injuries compatible with cerebral abscesses; for which he received treatment with antibiotics without improvement for what there takes biopsy of the injuries that reported tuberculomas, specific treatment being initiated later and the primary area being investigated without the same one be detecting. After the first procedural step with evident clinical and radiographic improvement. CONCLUSIONS: The tuberculosis in anyone of their forms of presentation must be included within the diagnosis differential of the patients in our endemic countries for this disease. The clinical and radiological diagnosis of cerebral injuries is difficult and single usually it obtains to the diagnosis during a pathology study that shows tuberculomas with caseosa necrosis, epiteliodes cell and the acid alcohol bacilli resistant.

Adult↗