Innervation of the intestinal muscular coat

Summary Nerve bundles have an uneven distribution in the muscularis externa of the guinea-pig ileum. They are absent in the longitudinal muscle layer, and are mainly concentrated between the two muscle layers and between the bulk of the circular layer and its innermost portion. The latter is formed by muscle cells which are smaller and more electron dense than the ordinary smooth muscle cells. In cross sections of the circular layer there are 5425 intramuscular axons (of which 921 contain vesicles) per 10000 smooth muscle cells, and they are grouped in bundles, mainly formed by 10–40 axons. The gap between axons and smooth muscle cells is generally hundreds of nanometres; only a few junctions with a gap smaller than 20 nm occur. Interstitial cells have a cytoplasm occupied mainly by smooth reticulum and ribosomes, and processes containing filaments. These processes are closely associated with smooth muscle cells and nerve bundles. Interstitial cells have no basal lamina. Nexuses are found in the circular but not in the longitudinal muscle layer. Attachment plaques and invaginating processes are found in both muscle layers. More complex interdigitations appear between contacting muscle cells. There are 84 intramuscular blood vessels per 10 000 cross-sectioned smooth muscle cells (or 1700 per mm²).     

Origin and filiation of human plasmacytoid dendritic cells

Human plasmacytoid dendritic cells represent a rare population of leukocytes which produce high amounts of type I interferon in response to certain viruses. Although those cells were first described in 1958, there are still unsolved issues related to their origin and function. Recently, a leukemic counterpart of plasmacytoid dendritic cells was identified. Molecular approaches using either normal or leukemic plasmacytoid dendritic cells provide some new insights into the controversial lymphoid origin of those cells. The need for specific markers is still a critical aspect for the identification of plasmacytoid dendritic cells, whatever stage of differentiation, in normal as well as in pathological conditions. Hopefully, novel markers will allow delineation of the relationships between dendritic cells at different stages of differentiation/maturation along the myeloid and lymphoid lineages.     

Sclerosteosis: report of a case in a black African man

Sclerosteosis is a rare genetic disorder of bone modelling, similar to, but distinct from, van Buchem disease; it has been described almost exclusively in Afrikaners of South Africa, a white population of Dutch ancestry. Isolated cases have been reported in a girl in Japan, a boy in Spain, and in multiracial families in Brazil and USA.
Here we report a case of sclerosteosis in a black man born in Senegal. He presented with the full features of the disease: tall stature; syndactyly; nail dysplasia; massive sclerosis of the long tubular bones, the ribs, the pelvis and the skull; multiple cranial nerve involvement: optic atrophy, facial palsy and trigeminal neuralgia. Radiologic examination, visual and brainstem auditory evoked potentials, computerized tomography and magnetic resonance imaging of the skull were performed. This seems to be the first case of the disease in a black African individual, with no known relationship with Dutch ancestry.     

Glycosylphosphatidylinositol-linked proteins are required for maintenance of a normal peripheral lymphoid compartment but not for lymphocyte development

Surface proteins tethered to the membrane through a glycosylphosphatidylinositol (GPI) anchor are deficient in the blood cells of patients with paroxysmal nocturnal hemoglobinuria (PNH) as result of a somatic mutation, in a hematopoietic stem cell, of the X-linked phosphatidylinositolglycan complementation group A (PIG-A) gene. In PNH patients, compared to the large numbers of GPI-deficient myeloid cells, the proportion of GPI-deficient lymphocytes tends to be low, and therefore the impact of GPI deficiency on immune function has been unclear. We have obtained complementation by Pig-a(-) embryonic stem (ES) cells of Rag(-/-) blastocysts, and we show that Pig-a(-) ES cells are able to reconstitute the T cell and B cell compartments of Rag(-/-) mice. Although these mice were immunologically competent, by comparison with appropriate controls we detected several abnormalities: (1) increased levels of IgG; (2) high frequency/titers of anti-nuclear antibodies; (3) markedly reduced delayed hypersensitivity; and (4) impaired activation-induced lymphocyte death in vitro. In some cases, aging Pig-a(-)/Rag(-/-) chimeric mice developed lymphadenopathy and polyclonal T cell and B cell expansion. Thus, GPI-linked proteins are not required for lymphocyte development but they are required for normal lymphocyte function and for maintaining normal peripheral lymphoid homeostasis.     

Cloning and characterization of two catechol 1,2-dioxygenase genes from Acinetobacter radioresistens S13

Two novel catechol 1,2-dioxygenase (C 1,2-O) genes have been isolated from an Acinetobacter radioresistens strain that grows on phenol or benzoate as sole carbon and energy source. Designated as catA(A) and catA(B), they encode proteins composed of 314 and 306 amino acids, whose deduced sequences indicate that they have approximately 53% identity, whereas their NH2-terminal and COOH-terminal regions have no sequences in common. This may explain their different thermal and pH stability. Polyclonal antibodies raised against an amino-terminal CatA(A) peptide or the whole CatA(B) protein were used to establish their inducible and differential expression patterns upon bacterial growth in phenol or benzoate. The CatA(A) protein (IsoA) was induced by both phenol and benzoate though with different kinetics, whereas the catA(B) product (IsoB) was constitutively produced at low levels that increased only during growth in the presence of benzoate.     

Candida albicans expresses a focal adhesion kinase-like protein that undergoes increased tyrosine phosphorylation upon yeast cell adhesion to vitronectin and the EA.hy 926 human endothelial cell line

The signaling pathways triggered by adherence of Candida albicans to the host cells or extracellular matrix are poorly understood. We provide here evidence in C. albicans yeasts of a p105 focal adhesion kinase (Fak)-like protein (that we termed CaFak), antigenically related to the vertebrate p125Fak, and its involvement in integrin-like-mediated fungus adhesion to vitronectin (VN) and EA.hy 926 human endothelial cell line. Biochemical analysis with different anti-chicken Fak antibodies identified CaFak as a 105-kDa protein and immunofluorescence and cytofluorimetric analysis on permeabilized cells specifically stain C. albicans yeasts; moreover, confocal microscopy evidences CaFak as a cytosolic protein that colocalizes on the membrane with the integrin-like VN receptors upon yeast adhesion to VN. The protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A strongly inhibited C. albicans yeast adhesion to VN and EA.hy 926 endothelial cells. Moreover, engagement of alpha v beta 3 and alpha v beta 5 integrin-like on C. albicans either by specific monoclonal antibodies or upon adhesion to VN or EA.hy 926 endothelial cells stimulates CaFak tyrosine phosphorylation that is blocked by PTK inhibitor. A role for CaFak in C. albicans yeast adhesion was also supported by the failure of VN to stimulate its tyrosine phosphorylation in a C. albicans mutant showing normal levels of CaFak and VNR-like integrins but displaying reduced adhesiveness to VN and EA.hy 926 endothelial cells. Our results suggest that C. albicans Fak-like protein is involved in the control of yeast cell adhesion to VN and endothelial cells.     

Role of Apoptosis in Autoimmunity

Autoimmune diseases are characterized by the activity of autoreactive lymphocytes that produce antibodies targeting self tissue or organ for destruction. Although the pathogenesis of these diseases is poorly understood, during the past two decades basic research has indicated apoptosis as the pivotal molecular mechanism leading to autoimmunity. Recently cytokines have been invoked in the regulation of the apoptosis-related factors and death receptors in autoimmune target destruction. These research advances have contributed to the identification of mechanisms controlling autoimmunity for defining novel therapeutic strategies.     

Fatal pulmonary arterial dissection and sudden death as initial manifestation of primary pulmonary hypertension: a case report.

We report a rare case of sudden death due to cardiac tamponade following intrapericardial rupture of a main pulmonary artery dissecting aneurysm. On pathology examination, the pulmonary artery showed an intimal tear in an arterial wall area with reduced thickness. However, no degenerative, inflammatory or necrotic processes were evident within the vessel wall. Hypertrophy of the wall of vasa vasorum in the adventitia of the pulmonary artery was found, as well as bilaterally diffuse myointimal arterial hyperplasia of the lung vasculature. According to these findings, we conclude that pulmonary artery rupture occurred in a patient with chronic unrecognized primary pulmonary hypertension.