Histology and histopathology Vol.14, nº 4 (1999)
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- PublicationOpen AccessSodium transport systems in human chondrocytes Morphological and functional expression of the Na+,K+-ATPase a and D subunit isoforms in healthy and arthritic chondrocytes(Murcia : F. Hernández, 1999) Trujillo, E.; Alvarez de la Rosa, D.; Mobasheri, A.; Ávila, J.; Gonzalez, T.; Martín Vasallo, P.The chondrocyte is the cell responsible for the maintenance of the articular cartilage matrix. The negative charges of proteoglycans of the matrix draw cations, principally Na+, into the matrix to balance the negative charge distribution. The Na+,Kf -ATPase is the plasma membrane enzyme that maintains the intracellular Na+ and K+ concentrations. The enzyme is composed of an a and a l3 subunit, so far, 4 a and 3 B isoforms have been identified in mammals. Chondrocytes are sensitive to their ionic and osmotic environment and are capable of adaptive responses to ionic environmental perturbations particularly changes to extracellular [Na+]. In this article we show that human fetal and adult chondrocytes express three a ( a l , a 2 and the neural form of a3) and the three l3 isoforms (131, l32 and 83) of the Na+,K+-ATPase. The presence of multiple Na+,K+-ATPase isoforms in the plasma membrane of chondrocytes suggests a variety of kinetic properties that reflects a cartilage specific and very fine specialization in order to maintain the Na+/K+ gradients. Changes in the ionic and osmotic environment of chondrocytes occur in osteoarthritis and rheumatoid arthritis as result of tissue hydration and proteoglycan loss leading to a fall in tissue Na+ and K+ content. Although the expression levels and cellular distribution of the proteins tested do not vary, we detect changes in p-nitrophenylphosphatase activity "in situ" between control and pathological samples. This change in the sodium pump enzymatic activity suggests that the chondrocyte responds to these cationic environmental changes with a variation of the active isozyme types present in the plasma membrane.
- PublicationOpen AccessAntisense oligonucleotides to stromelysin mRNA inhibit injury-induced proliferation of arterial smooth muscle cells(Murcia : F. Hernández, 1999) Lovdahl, C.; Thyberg, J.; Cercek, B.; Blomgren, K.; Dimayuga, P.; Kallin, B.; Hultghrdh-Nilsson, A.Smooth muscle cell migration and proliferation are important events in the formation of intimal lesions associated with atherosclerosis and restenosis following balloon angioplasty. To make this possible, the smooth muscle cell has to change from a contractile to an activated repair cell with capacity to synthesize DNA and extracellular matrix components. There is now considerable evidence that the extracellular matrix has important functions in modulating the phenotypic properties of smooth muscle cells, but less is known about the role of the matrix metalloproteinases. The present study investigates the role of stromelysin in the modulation of rat aortic smooth muscle cell morphology and function following mechanical injury in vitro and in vivo. Antisense mRNA oligonucleotides were used to investigate the role of stromelysin expression in injury-induced phenotypic modulation and the subsequent migration and proliferation of vascular smooth muscle cells. Cultured rat aortic smooth muscle cells and balloon-injured rat carotid arteries were used as experimental models. Light- and electron microscopy were used to follow changes in smooth muscle cell phenotype and lesion formation and incorporation of 3 ~ - thymidine to detect DNA synthesis. Injury-induced DNA synthesis and migration in vitro were inhibited by 72% and 36%, respectively, by adding stromelysin antisense oligonucleotides to the medium prior to injury. In primary cultures, 67% of the smooth muscle cells treated with stromelysin antisense were retained in a contractile phenotype as judged by analysis of cell fine structure, compared to 15% untreated cells and 40% in cells treated with mismatched oligonucleotides. Examination of the carotid arteries one week after balloon injury likewise demonstrated a larger fraction of contractile cells in the inner parts of the media in vessels treated with antisense oligonucleotides compared to Offprint requests to: Anna HultgArdh-Nilsson, Lund University, Departrnent of Cell and Molecular Biology, Division of Connective Tissue Biology, P. O. Box 94, S-221 00 Lund, Sweden. Fax: t46-46-211 3417. e-rnail: Anna.Hultgardh@rnedkern.lu.se those treated with mismatched oligonucleotides. The neointima was also distinctly thinner in antisense-treated than in mismatched-treated and control arteries at this time. These findings indicate that stromelysin mRNA antisense oligonucleotides inhibited phenotypic modulation of rat arterial smooth muscle cells and so caused a decrease in migration and proliferation and neointima formation in response to vessel wall injury.
- PublicationOpen AccessNovel insight into current models of NADPH oxidase regulation, assembly and localization in human polymorphonuclear leukocytes(Murcia : F. Hernández, 1999) Kobayashi, T.; Seguchi, H.We review herein the definition of the NADPH oxidase-activating site in human neutrophils and eosinophils, together with the new biochemical findings of the assembly of NADPH oxidase components and the signal transduction for the activation of NADPH oxidase. The activation of this enzyme is associated with multiple interrelated signaling pathways. Upon cell stimulation, the second messengers act on the assembly of NADPH oxidase components. The cytosolic components are first phosphorylated, and then associated with the membrane components. Small GTP-binding proteins and cytoskeletal components also participate in the activation of the NADPH oxidase. The cytochemical findings demonstrate that the superoxide generated by NADPH oxidase activity is initially localized in distinct types of intracellular granules, and not at the plasma membrane as previously believed. Thus, the assembly of NADPH oxidase components possibly occurs at the limiting membrane of the intracellular compartments. The oxidant-producing compartments mobilize and become associated with the plasma membrane upon cell stimulation with soluble stimulants, or fuse to phagosomes upon stimulation with particulate stimulants. Accordingly, superoxide is released to the extracellular space and into phagosomes in proportion to the oxidant-producing intracellular granule association with the plasma membrane and with the phagosomal membrane, respectively.
- PublicationOpen AccessBone marrow histopathology in chronic myelogenous leukemia ,CML, evaluation of distinctive features with clinical impact(Murcia : F. Hernández, 1999) Thiele, J.; Kvasnicka, H.M.; Fischer, R.Bone marrow features in stable-phase chronic myelogenous leukemia (CML) are characterized by a striking heterogeneity which is determinable by appropriate means including representative pre-treatment trephine biopsies, immunohistochemistry and morphometry. Cell lineages involved to a variable extent consist not only of neutrophil granulopoiesis, but include also megakaryocytes, erythroid precursors, resident macrophages and lymphocytes. Moreover, the stromal compartment, in particular reticulin and collagen fibers, plays a pivotal role in the disease process. Following morphometric analysis significant correlations may be calculated between histological parameters and clinicallaboratory findings. Relevant interactions are detectable between number of megakaryocytes and their precursors with fiber density. This finding is in line with the close functional relationships between megakaryopoiesis and fibroblasts regarding the complex pathomechanisms of myelofibrosis. Moreover, other correlations are observable between reduction of erythropoiesis or increase in fibers with clinical features like anemia, percentages of myelo- and erythroblasts in the peripheral blood, spleen size or LDH level. These variables are in keeping with more advanced stages of CML which indicate a transition to myeloid metaplasia and thus exert a significant impact on survival. Consequently, the different risk profiles of patients are determined by both clinical and morphological parameters of predictive value. Regarding the latter, extent of myelofibrosis, amount of erythroid precursors and numbers of myeloerythroblasts in the peripheral blood are significantly associated with prognosis. For this reason, it should be mandatory to enter morphological criteria into prospective clinical trials on CML, not only for diagnotic purpose, but also for a proper evaluation of different survival patterns.
- PublicationOpen AccessHeart mitochondria in rats submitted to chronic hypoxia(Murcia : F. Hernández, 1999) Cervós-Navarro, J.; Kunas, R.Ch.; Sampaolo, S.; Mansmann, U.The effect of prolonged exposure to normobaric hypoxia on the mitochondria of myocard of rats exposed for several weeks to 8 and 7% O2 has been morphometrically evaluated. Twelve male Wistar rats housed in Nalgene cages (2 per cage) with a batch of six cages placed in plexiglass chambers were maintained in air/N2 mixtures containing different concentrations of 02. Six animals kept in similar cages under normoxia served as controls. When at day 60 the FIOZ was reduced to 8%, the weight increase stagnated and after the 81st test day, on which the hypoxic animals were subdivided into 8% and 7% groups the weight curve showed a decrease in the mean body weight for both groups. The arrest and the following loss of weight beyond the 85th day may be interpreted as the expression of a limit reached in the compensation capacity. In the 8%-group the shape of the mitochondria varied more markedly often with budding and furrowing of the surface. In the 7%-group bizarre shapes and wide variations in size with a decided shift towards larger mitochondria were noteworthy. While rats kept under 8% oxygen exhibited a numerical increase in myocardial mitochondria compared to controls, the mitochondria of the 7%-group were numerically reduced. The results suggest that hypoxia of 8% oxygen is compensatable, if only to some extent, by an increasing surface of mitochondrial membranes, and that further reduction of oxygen causes compensation mechanisms to fail as seen by the severe alterations of the mitochondrial population of the cardiomyocyte in the 7%-group.