Histology and histopathology Vol.17, nº 3 (2002)

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Open Access
Knocked out by Rho Rac T-cell biology
(Murcia : F. Hernández, 2002) Bustelo, X.R.
The Rho/Rac family is a group of Ras-related proteins with demonstrated roles in the regulation of proliferation and cytoskeletal structures in a number of cell lineages. Despite this, the actual role of these proteins in T-cells could not be addressed in vivo due to the lack of adequate animal models. Recently, the use of knockout and transgenic animals for Rac1, Rac2, and RhoA has provided a genetic proof of the importance of Rho/Rac protein in different aspects of T-cell signaling. These animals have also allowed us to get better views about the influence of these GTPases proteins on the maturation decisions of immature lymphocytes and on the signaling strategies these GTPases utilize to favor the generation of coherent and robust immune responses.
Open Access
Abnormal cochlea linked to deafness in transgenic mice expressing human cytokeratin K8
(Murcia : F. Hernández, 2002) Bartolome, M.V.; Casanova, M.Ll.; Carricondo, F.; Del Castillo, E.; Jorcano, J.L.; Gil-Loyzaga, P.
The cytokeratin intermediate filaments have a relevant role in the proliferation and differentiation processes of epithelial cells. To provide information about the role of K8 cytokeratin during the auditory receptor differentiation, two groups of adult mice were used: TGK8-4 transgenic and control animals. The TGK8-4 transgenic mice contained 12 kb of K8 human cytokeratin (HK8) locus (Casanova et al., 1995, 1999). The functional activity of the auditory receptor was analyzed by auditory thresholds. Morphological studies demonstrate that the auditory receptors of the TGK8-4 transgenic mice are highly immature. Immunocytochemical studies were made by using two monoclonal antibodies: CAM 5-2 (recognizing K8 human cytokeratin) and Troma-1 (recognizing both mouse and human K8 cytokeratin). These demonstrated significant differences between the auditory receptors of the transgenic mice and the control mice. These functional and morphological differences clearly suggest that K8 cytokeratin has a relevant role during the differentiation and tridimensional organization of the sensory and the supporting cells of the auditory receptor.
Open Access
A micro-anatomical model of the distribution of myocardial endomysial collagen
(Murcia : F. Hernández, 2002) Macchiarelli, G.; Ohtani, O.; Nottola, S.A.; Stallone, T.; Camboni, A.; Prado, I.M.; Motta, P.M.
Myocardial connective tissue probably provides passive support for regulating heart tensile strength and stiffness and ultimately for controlling heart mechanics through its endomysial part. However, endomysial collagen micro-arrangement is still a matter of debate. In order to define the fine distribution of left ventricle endomysial collagen, we applied the NaOHscanning electron microscopy (SEM) maceration method (one of the techniques of choice for studying collagen micro-arrangement) to rabbit heart. Gomori-reticulum staining was used for correlated light microscopy (LM) observations. The SEM-NaOH method allowed isolation of collagen by removing other extracellular matrix components and cells and preserved collagen structure and position. Endomysial collagen appeared arranged in laminae that delimited the lacunae that were left empty by macerated myocytes and small vessels (mostly capillaries). These laminae were formed by reticular fibers, as confirmed by LM observations of Gomorireticulum- stained samples, and were organized in irregularly meshed networks made of thin (single) and thick (composed) filaments. In longitudinal views, collagen laminae extended the entire length of lacunae. In transversal views, the cut surface of the laminae appeared to be made of collagen bundles. These observations provide an updated microanatomical view of endomysial collagen distribution, which integrates previous studies. This model is based on the evidence that collagen laminae enveloped the surface of small vessels and myocytes. Thus, a type of myocyte-myocyte or capillary-myocyte "laminar connection" anchored to the entire cell length here is emphasized, rather than a type of "strut connection" anchored to defined loci, as usually described. This structure explains better how endomysium may provide the necessary support for heart compliance and protection against overstretch.
Open Access
Circulating nucleic acids as a tumor marker
(Murcia : F. Hernández, 2002) Chan, K.C.A.; Lo, Y.M.D.
Patients suffering from malignant diseases have been shown to have increased amounts of cell free nucleic acids in their circulation. As genetic and epigenetic alterations are increasingly characterized in different types of tumors, such changes can be used to detect tumor-derived nucleic acids in the circulation. To date, nearly all tumor-associated nucleic acids have been detected in the plasma or serum of cancer patients. Moreover, increased levels of circulating viral nucleic acids have also been demonstrated in patients with certain cancers associated with viral infections. The concentration of these tumor-associated nucleic acid species is generally related to the tumor load and the extent of the disease. Serial monitoring of plasma nucleic acids thus provides a good way to follow disease progress and to predict the outcome of such patients. In this review, different approaches of detecting tumorrelated nucleic acids in the circulation and their potential as tumor markers in the screening, monitoring and prognostication of malignant diseases are discussed.
Open Access
The Rho small GTPase Functions in health and disease
(Murcia : F. Hernández, 2002) Toksoz, D.; Merdek, K.D.
Cell shape changes, contractility, adhesion, migration, gene transcription, cytokinesis, membrane trafficking, and growth, require Rho small GTPase function. The basis for this is that Rho regulates actin filament assembly, and serum response factor (SRF)- mediated gene transcription. Upon activation by serum or cell adhesion, Rho stimulates a distinct signal transduction pathway that induces cytoskeletal and transcriptional responses through diverse effectors. Rho activity is tightly controlled by guanine nucleotide exchange factors, GTPase activating proteins, and guanine dissociation inhibitors. Dysregulation of the Rho pathway is implicated in multiple pathological conditions including cancer and metastasis, cardiovascular disease, bacterial and viral pathogenesis, hepatic disease, and developmental disorders.
Open Access
Trypanosoma cruzi infection patterns in intact and athymic mice of susceptible and resistant genotypes
(Murcia : F. Hernández, 2002) Gonçalves da Costa, S.C.; Calabrese, K.S.; Zaverucha do Valle, T.; Lagrange, P.H.
Inbred strains of mice inoculated with the T. cruzi Y strain behaved as susceptible (A/J, C3H/HeN), intermediate (BALB/c) or relatively resistant (C57BL/6) with respect to the magnitude of parasitaemia and mortality rate. C57BL/10 mice were susceptible in relation to parasitaemia but resistant when mortality was analyzed. Infection with T. cruzi CL strain presented the same results, except for C57BL/6 which behaved as susceptible mice. Athymic mice of various backgrounds revealed no differences in susceptibility, presenting the same dramatic parasitaemia, tissue colonization pattern and no inflammatory reaction in any of the tissues studied. Infection of euthymic and athymic BALB/c mice elicited the production of parasite-specific antibodies, which reached similar levels on the first 9 days but differed after day 13. Serum transfer experiments in BALB/c mice did not show great differences in parasitaemia but altered T. cruzi polymorphism reducing the slender forms in athymic mice. Histopathology of athymic BALB/c mice showed the same tissue tropism when infected either with T. cruzi Y or CL strain.
Open Access
Computer-aided morphometric analysis of the developing concentric structure of the human fetal intestinal tube
(Murcia : F. Hernández, 2002) Bagyánszki, M.; Kovács, É.G.; Resch, B.A.; Román, V.; Resch, B.E.; Fekete, Eva
The Image-Pro Plus 3.0 morphometric program was used to study the region-specific organization of the human fetal intestine across the radial axis of the gut at weeks 12 and 18 of gestation. The thicknesses of the epithelium, the submucosa, the muscular layers and the myenteric ganglia were measured in resin-embedded semithin sections. Statistical analysis of the collected data was performed by using the two-way ANOVA, the SNK test and the Pearson correlation. The structural changes relating to the gut morphogenesis within this developmental period were followed both light and electron microscopically. The various tissues forming the radial axis of the intestinal tube exhibited different trends concerning their individual development. The thickness of the epithelium did not change in the fetal period investigated, although the epithelial surface displayed characteristic ultrastructural changes. The thickness of the submucosal layer increased significantly, but with different dynamics along the longitudinal axis, whereas the increases in size of the muscular layers and the myenteric ganglia did not differ significantly along the longitudinal axis of the embryonic intestine. The Pearson correlation revealed a significant correlation between the development of the circular muscle layer and that of the myenteric plexus along the whole length of the intestinal tube. The epithelium, the submucosa and the longitudinal muscle layers developed independently between weeks 12 and 18 of gestation.
Open Access
CD44: functional relevance to inflammation and malignancy
(Murcia : F. Hernández, 2002) Yasuda, M.; Nakano, K.; Yasumoto, K.; Tanaka, Y.
CD44 is a principal cell surface receptor for hyaluronan, a major component of extracellular matrices. Cells are surrounded by and encounter matrix in vivo, which in turn serves a variety of cell functions through the direct adhesion via their receptors. CD44 communicates cell-matrix interactions into the cell via “outside-in signaling” and has an important role in biological activities. The interaction of CD44 with fragmented hyaluronan on rheumatoid synovial cells induces expression of VCAM-1 and Fas on the cells, which leads to Fas-mediated apoptosis of synovial cells by the interaction of T cells bearing FasL. On the other hand, engagement of CD44 on tumor cells derived from lung cancer reduces Fas expression and Fas-mediated apoptosis, resulting in less susceptibility of the cells to CTL-mediated cytotoxicity through Fas-FasL pathway. Thus, although the CD44-mediated signaling differs among cells and circumstances, we here propose the functional role of CD44 in inflammatory processes and tumor susceptibility and the rational design of future therapeutic strategies including the exploitation of CD44-mediated pathway in vivo.
Open Access
STAT and SMAD signaling in cancer
(Murcia : F. Hernández, 2002) Iwamoto, T.; Oshima, K.; Senga, T.; Feng, X.; Oo, M.L.; Hamaguchi, M.; Matsuda, S.
STAT and SMAD often exert opposite biological effects on diverse cellular functions. Recent studies have shown that STAT can interface with SMAD at molecular level and that some novel molecules, such as SOCS (also called CIS) and APRO6 (also called TOB), modulate this signaling. A cofactor p300/CBP might act as a bridging molecule to mediate the interface. Thus, STAT and SMAD signaling pathways may crosstalk each other with interweaved regulatory mechanisms. Interestingly, the importance of all the proteins’ function has been shown by the increasing evidence of their involvement in cancer. These recent progresses have been made in attributing novel exciting functions. Accordingly, we would like to review the latest advances of those pathways on a cross-section in cancer signaling.
Open Access
Inflammatory cells induce neointimal growth in a rat arterial autograft model
(Murcia : F. Hernández, 2002) Jurado, F.; Bellón, J.M.; Rodríguez, M.; Corrales, C.; Buján, J.
Subendothelial invasion by leukocytes is a sign of intimal thickening in arteriosclerosis and in the response of a vessel to mechanical damage. Our study was designed to establish whether these cells are implicated in the formation of a neointima in an autologous arterial graft model in the rat and to evaluate the effects of cyclosporin A (CsA). Three study groups were established according to whether the animals were treated with CsA-Cp (Sandimmun)®, CsA-Et (ethanol vehicle) or received no treatment (control group). Both drug forms were administered (5 mg/kg/day, s.c.) from 4 days prior to surgery until the time of sacrifice. Antibodies specific for lymphocytes (CD4, CD8), monocytes/macrophages-ED1, smooth muscle a-actin and the von Willebrand factor (vWF) were used to identify the cells in the grafted arterial wall. In control grafts, the neointima had formed by 2 weeks postimplant. However, the cells comprising this layer generally presented no positivity whatsoever towards the antibodies employed. At 50 days, the new layer was observed to be formed by a vWF-positive endothelium and a-actin-positive cells. In all three groups, several polymorphonuclear (PMN) cells adhered to the denuded luminal surface from 7 days onwards. In the treated animals, neutrophils and monocytes were seen to infiltrate intimal and medial layers during the later postimplant stages. Around the third week post-implant, the neointima had reached the grafted segment from the distal portion of the recipient artery, and by 50 days it was similar to that seen in control specimens. Our findings suggest that: a) neutrophils play a role in neointimal thickening in this arterial autograft model; and b) CsA promotes the adhesion and infiltration of neutrophils in the injured arterial wall.
Open Access
GADD153 is an independent prognostic factor in melanoma immunohistochemical and molecular genetic analysis
(Murcia : F. Hernández, 2002) Korabiowska, M.; Cordon-Cardo, C.; Betke, H.; Schlott, T.; Kotthaus, M.; Stachura, J.; Brinck, U.
The main role of growth arrest and DNA damage-inducible (GADD) genes is to block proliferation at G1 and G2 checkpoints in response to DNA damage. The goal of this study was to examine the expression of GADD genes in primary melanomas with respect to prognosis. GADD34 was found in 73% of the primary melanomas investigated. GADD45 and GADD153 were positive in 60% and 80% of primary melanomas, respectively. Cox regression demonstrated that only GADD153 had any independent prognostic impact. We therefore decided to establish a PCR assay for detection of GADD153 in paraffin-embedded tissue. GADD153 deletion was found in 3/26 melanomas. None of the 3 cases with GADD153 deletion showed any expression of GADD153. Sequencing analysis detected polymorphism T-C at amino acid position 10 in 6/23 melanomas. In 6 cases with GADD153 polymorphism, GADD153 expression was found in 2 melanomas with a maximum GADD153 index of 10%. We postulate that the GADD gene family plays an important role in melanoma progression.
Open Access
Biliary papillary neoplasm of the liver
(Murcia : F. Hernández, 2002) Nakanuma, Y.; Sasaki, M.; Ishikawa, A.; Tsui, W.; Chen, T.C.; Huang, S.F.
Biliary papillary neoplasia of the liver characterized by intraductal papillary growth of neoplastic biliary epithelia with a fine fibrovascular stalk has been sporadically reported, and includes intraductal growing cholangiocarcinoma and biliary papillomatosis. In addition, biliary papillary dysplasia and in situ and microinvasive carcinoma with papillary configuration reported in hepatolithiasis and in other chronic biliary diseases, could be included in this category. Usually, they arise in the intrahepatic large bile ducts, and the neoplastic and non-neoplastic parts of the intrahepatic biliary tree show saccular and segmental dilatation with mucin hypersecretion. This neoplasia frequently shows intraductal spreading and peribiliary glandular involvement. Acute repeated episodes of cholangitis or obstructive jaundice are a frequent clinical manifestation. Gastroenteric metaplasia with aberrant expression of cytokeratin 20, MUC2, MUC5AC, and/or MUC6, is frequent in the neoplastic parts, and biliary epithelial dysplasia with such metaplasia may give rise to in situ and then invasive carcinoma in hepatolithiasis. Interestingly, this type tends to contain foci of mucinous carcinoma elements, and this element may be predominant (mucinous carcinoma). Some may progress to “mucinous biliary cystadenocarcinoma” without ovarian mesenchymal stroma and with intraluminal continuous growth into the neighboring bile duct lumens. Interestingly, the biliary papillary neoplasm resembles histologically, phenotypically and clinically intraductal papillary mucinous neoplasm of the pancreas which is now being established as an infrequent, slowgrowing pancreatic neoplasm. Recognition of such biliary papillary neoplasm with respect to the pancreatic equivalent may lead to a better understanding and further studies of the intrahepatic biliary neoplasm.
Open Access
Influence of chronic treatment with the growth hormone secretagogue Ipamorelin, in young female rats somatotroph response in vitro
(Murcia : F. Hernández, 2002) Jiménez Reina, L.; Cañete, R.; De la Torre, M.J.; Bernal, G.
Growth hormone (GH) is secreted in the anterior pituitary gland by the somatotroph cells. Secretion is regulated by growth hormone releasing hormone (GHRH) and somatostatin. Morever, GH secretagogues (GHS) can exert a considerable effect on GH secretion. In order to determine the effects of chronic treatment with the GHS Ipamorelin on the composition of the somatotroph cell population and on somatotroph GH content, an in vitro analysis was performed of the percentage of somatotroph cells (% of total), the ratio of different GH cell types (strongly/weakly-staining) and individual GH content, in pituitary cell cultures obtained from young female rats receiving Ipamorelin over 21 days (Ipamorelin group) and the effects were compared with those of GHRH (GHRH group) or saline (saline group). The ultrastructure of somatotroph cells did not change, but the volume density of secretion granules was increased (P<0.05) by previous in vivo Ipamorelin or GHRH treatment. In 3-day basal pituitary cell monolayer cultures, the percentage of somatotroph cells showed no modifications between groups, nor was there any change in the ratio of strongly/weakly immunostaining GH cells. In the Ipamorelin group alone, in vitro treatment with Ipamorelin (10-8 M), or GHRP 6 (10-8 M), or GHRH (10-8 M) for 4 hours, increased the percentage of somatotroph cells, without modifying the ratio of strongly/weakly immunostained GH cells. Basal intracellular GH content in somatotroph cells over 4 hours was lower in the Ipamorelin group and the GHRH group than in the saline group. Only in the Ipamorelin group did Ipamorelin (10-8 M), GHRP 6 (10-8 M) and GHRH (10-8 M) prompt increased intracellular GH content. These data suggest that, at least in the young female rat, the GHS Ipamorelin is able to exert a dynamic control effect on the somatotroph population and on GH hormone content.
Open Access
Location of Zinc and 65Zn in spinal ganglia of the rat
(Murcia : F. Hernández, 2002) Perez-Castejon, M.C.; Vera-Gil, A.; Lahoz, M.; Aisa, J.; Recreo, M.P.; Pes, N.; Serrano, P.; Barral, M.J.
Following the works of Velazquez et al. (1999), Jo-Seung et al. (2000), Wang et al. (2001), Danscher et al. (2001) and the criteria of Zinc-containing neurons established by Frederickson et al.(2000), we have found the presence and localisation of Zinc in the neurons of the dorsal root ganglia of Wistar rat, by using Timm’s thecnique and by studying the autoradiographic uptake of 65Zn. The agreement between the results of both techniques allows us to classify these spinal ganglion neurons as Zinc-containing neurons and also, to confirm some of the results of Velazquez et al. (1999)
Open Access
Immunoexpression of the hepatocyte growth factor (HGF), HGF-receptor (c-met) and STAT3 on placental tissues from malformed fetuses
(Murcia : F. Hernández, 2002) Trovato, M.; Grosso, Maddalena; Vitarelli, E.; Benvenga, S.; Trimarchi, F.; Barresi, G.
To characterize the possible relationship between the expression of the HGF/HGF-R system with transcription factor STAT3, responsible for morphogenetic response of HGF stimulation, and the embryonic development alterations, we investigated, by immunohistochemistry, the expression of HGF, c-met and STAT3 in 9 placentas from malformed fetuses and 9 control placentas from non-malformed fetuses. The major and distinct patterns of expression characterizing the placentas from malformed fetuses were a higher percentage mean of stromal cells stained for HGF, c-met and STAT3 antibodies (60%, 66% and 54%, respectively on fibroblast cells and 44%, 57% and 42%, respectively on myofibroblast cells) and a lower percentage mean of cytotrophoblast cells stained for the same antibodies (2%, 2% and 1%, respectively), than in control placentas. In fact, in this latter group, the stromal fibroblast cells were stained in a percentage mean of 27%, 22% and 7%, respectively; the stromal myofibroblast cells in a percentage mean of 5%, 6% and 2%, respectively and the cytotrophoblast cells in a percentage mean of 25%, 34% and 18%, respectively. The expression of each antibody on stromal cells in both groups suggests an alternative role of the HGF/HGF-R system activating the via STAT3 transdution and operating on placental tissues, overall in organogenesis alteration conditions. This immunohistochemical approach could be used in the diagnostic practice of pathologists on chorionic villi biopsy when genetic alterations are absent and ultrasound aspects are doubtful for malformations.
Open Access
Expression of p53 and its transcriptional target genes mRNAs in the ethylnitrosourea-induced apoptosis and cell cycle arrest in the fetal central nervous system
(Murcia : F. Hernández, 2002) Katayama, K.; Ohtsuka, R.; Takai, H.; Nakayama, Hiroyuki; Doi, K.
Ethylnitrosourea (ENU) is an alkylating agent and we previously clarified that it induced apoptosis and cell cycle arrest in the fetal central nervous system (CNS). In the present study, we studied the expression of p53 and its transcriptional target genes to investigate the role of p53 in the ENU-induced apoptosis and cell cycle arrest in the fetal CNS following the administration to dams on day 13 of gestation (GD13). Although the enhancement of p53 mRNA expression was not detected by reverse transcription and polymerase chain reaction (RT-PCR), p53-positive signals were detected immunohistochemically in the nuclei of neuroepithelial cells of the ENU-administered fetuses from 1 hour after treatment (HAT) to 12HAT, and they were most intensive at 3HAT. On the other hand, p53-positive signals were scarcely detected in the control fetuses. Among the p53 target genes, the expression of p21, bax, cyclinG1 and fas mRNAs increased and peaked at 6HAT. In addition, strong immunoreactivity for p21 was detected in the nuclei of neuroepithelial cells of the fetuses at 6HAT. The expression of p53 protein increased prior to the induction of apoptosis and cell cycle arrest, and transcription of its target genes was also activated. The present results suggest that ENU may induce apoptosis and cell cycle arrest in the fetal neuroepithelial cells in a p53-dependent manner.
Open Access
Rab3D a regulator of exocytosis in non-neuronal cells
(Murcia : F. Hernández, 2002) Millar, A.L.; Pavlos, N.J.; Xu, J.; Zheng, M.H.
Rab3D, a small Ras-like GTPase, is a key regulator of intracellular vesicle transport during exocytosis. It has been shown that Rab3 GTPases are abundant in cells with regulated secretory pathways and are thought to confer the specificity of docking and fusion during regulated exocytosis. Unlike other Rab3 isoforms, Rab3D is enriched in a number of nonneuronal tissues and is localised to secretory granules in the cytoplasm of these cells. The structure of Rab3D exhibits all of the conserved domains from the Rab family and also contains hypervariable N- and Cterminal regions. Rab3D undergoes post-translational isoprenylation and cycles between GDP- and GTPbound forms. Apart from the factors involved in the Rab activation cycle, few Rab3D effector proteins have been identified to date. Nevertheless, it has long been suggested that Rab3D plays a role in regulated exocytotic processes as well as apically directed transcytosis. This review summarises the recent work on the biological function, structural integrity and molecular interactions of Rab3D in non-neuronal cells.
Open Access
The role of the angiogenic molecule VEGF in the pathogenesis of rheumatoid arthritis
(Murcia : F. Hernández, 2002) Afuwape, A.O.; Kiriakidis, S.; Paleolog, E.M.
The expansion of the synovial lining of joints in rheumatoid arthritis (RA), and the subsequent invasion by the pannus of underlying cartilage and bone, necessitates an increase in the vascular supply to the synovium, to cope with the increased requirement for oxygen and nutrients. New blood vessel formation - ‘angiogenesis’ - is now recognised as a key event in the formation and maintenance of the pannus in RA. Although many pro-angiogenic factors have been demonstrated to be expressed in RA synovium, the potent pro-angiogenic cytokine vascular endothelial growth factor (VEGF) has been demonstrated to have a central involvement in the angiogenic process in RA. The additional activity of VEGF as a vascular permeability factor may also increase oedema and hence joint swelling in RA. Several studies, including those from the Kennedy Institute of Rheumatology Division, have shown that targeting angiogenesis in animal models of arthritis ameliorates disease. Inhibition of angiogenesis, as an adjunct to existing therapy of RA, or even as a stand-alone treatment, would not only prevent delivery of nutrients to the synovium, but could also lead to vessel regression and possibly reversal of disease.
Open Access
Physiology and pathophysiology of nitric oxide in the nervous system, with special mention of the islands of Calleja and the circunventricular organs
(Murcia : F. Hernández, 2002) Rodrigo, J.; Alonso, D.; Bentura, M.L.; Castro-Blanco, S.; Encinas, J.M.; Fernández, A.P.; Fernández-Vizarra, P.; Richart, A.; Santacana, M.; Serrano, J.; Martínez, A.
Nitric oxide (NO) has been recognized as a key regulatory factor in many physiological processes, including central nervous system function, development, and phatophysiology. NO is produced by a class of enzymes known as NO synthases (NOS) and in normal adult animals only the neuronal isoform (nNOS) is detectable. During cortical development, nNOS was found at E14 in neuroblasts of the marginal zone and its expression raised to a zenith by P5, decreasing afterwards until reaching a steady level by P10. At that time, nNOS was found mainly in pyramidal neurons. Interestingly, the inducible isoform of the enzyme (iNOS) was also active from P3 to P7, but it disappeared almost completely by P20. The neurodegeneration observed during normal aging and following hypoxic accidents seems to be the result of cumulative free radical damage, and excessive production of NO may be at the basis of the cascade. After ischemic events we observed an elevation in the number of neurons expressing nNOS coincident with an elevation in Ca2+- dependent NOS activity for up to 120 min. After this period, nNOS activity began to decrease but it was substituted by a rapid increase in Ca2+-independent activity coincident with the histological appearance of previously undetectable iNOS-immunoreactive neurons. These increases in NO production were accompanied by specific patterns of protein nitration, a process that seems to result in loss of protein function. In particular, we observed a correlation between exposure to ischemia-reperfusion and nitration of cytochrome c. This process was coincident with the exit of the cytochrome from the mitochondria to the surrounding cytoplasm, an early event in neuronal apoptosis. Interestingly, most of the morphological and molecular changes associated with ischemic damage were prevented by treatment with inhibitors of NO production, indicating a clear path in the search for efficacious drugs in the battle against cerebrovascular accidents.
Open Access
Antiproliferative effect of topic hyaluronic acid gel. Study in gingival biopsies of patients with periodontal disease
(Murcia : F. Hernández, 2002) Mesa, F.L.; Aneiros, J.; Cabrera, A.; Bravo, M.; Caballero, T.; Revelles, F.; Del Moral, R.G.; O’Valle, F.
Hyaluronic acid (HA) is the most abundant glycosaminoglycan of high molecular weight in the extracellular matrix of soft periodontal tissues. Our group recently demonstrated an HA-induced reduction in lymphoplasmocyte inflammatory infiltrate in periodontal disease. The objective of this study was to determine the effect of an HA gel of high molecular weight on cell proliferation, inflammation, and different periodontal lesion parameters. A double-blind clinical trial was conducted on the effect of an HA gel on cell proliferation in gingival biopsies from 28 patients with periodontal disease. A split-mouth design was used, randomly applying the gel to one quadrant and a placebo to the contralateral one. A gingival biopsy was taken for histopathological and immunohistochemical study, in order to determine the expression of cell proliferation antigen Ki-67 and to evaluate the inflammatory infiltrate. HA gel treatment induced a significant reduction in the proliferation index of the gingival epithelium, with 276 (range 234-317) Ki-67-positive cells per mm2 in treated samples versus 514 (range 158-876) per mm2 in controls (Mann-Whitney U test, p<0.003). In 13 patients, the number of Ki-67-positive fibroblastic cells was reduced by the treatment, whereas in 6 patients no differences were found (global difference, p=0.12). In 10 patients, Ki-67-positive cells were decreased in chronic inflammatory infiltrate present in the lamina propria, whereas in 6 patients no differences were found (global difference, p=0.054). We conclude that high molecular-weight HA gel reduces cell proliferation in epithelial cells such as fibroblasts and lymphocytes, abates the inflammatory process, and improves the periodontal lesion in patients with chronic periodontitis.