Histology and histopathology Vol.14, nº 4 (1999)

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Open Access
Quantitative in situ hybridization for the evaluation of gene expression in asynchronous and synchronized cell cultures and in tissue sections
(Murcia : F. Hernández, 1999) Barlati, S.; Zoppi, N.; Copeta, A.; Tavian, D.; De Petro, G.; Colombi, M.
We describe an image analysis (IA) system that has been applied for the quantitative evaluation of mRNAs evidenced by in situ hybridization (ISH) with radiolabelled probes in cultured cells and in tissue sections. The ISH-IA method was used for the evaluation of cultured cell morphological parameters such as cell and nucleous area (CA and NA, respectively) in parallel with the levels of mRNAs detected as hybridization grains areas (GA). The evaluation of these parameters, together with the analysis of the levels of mRNAs (c-jun, cyclin A) specific for given cell cycle phases (i.e. G1 and S/G2), allowed the identification, in asynchronous cultures of human skin fibroblasts, of cells in G1 and SlG2 phases. The mRNA levels measured by ISH-AI were comparable with those detected by RT-PCR. This method was also applied for the analysis of fibronectin (FN) gene expression in control skin fibroblasts in relationship with the different phases of the cell cycle and in comparison with a tumor cell line (Sk-Hepl), heterogeneous either for morphometric parameters or for the levels of this transcript. Finally, the ISH-AI was applied for the semiquantitative evaluation of the expression, localization and alternative splicing pattern of FN mRNA in normal liver and in hepatocellular carcinoma (HCC) tissue sections.
Open Access
Heart 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.
Open Access
Sodium transport systems in human chondrocytes II. Expression of ENaC, Na+ K+ 2CI- cotransporter and Na+ H+ exchangers in healthy
(Murcia : F. Hernández, 1999) Trujillo, E.; Alvarez de la Rosa, D.; Mobasheri, A.; Gonzalez, T.; Canessa, C.M.; Martín Vasallo, P.
In this article, the second of two, we continue our studies of sodium-dependent transport systems in human cartilage from healthy individuals and with osteoarthritis (OA) and rheumatoid arthritis (RA). We demonstrate the presence of the epithelia1 sodium channel (ENaC), previously undescribed in chondrocytes. This system is composed of three subunits, a, 13 and y. We have shown that the human chondrocytes express at least the a and the l3 subunit of ENaC. The expression of these subunits is altered in arthritic chondrocytes. In RA samples the quantity of a and B is significantly higher than in control samples. On the other hand, ENaC a and B subunits are absent in the chondrocytes of OA cartilage. Human chondrocytes also possess three isoforms of the Na+/H+ exchanger (NHE), NHE1, NHE2 and NHE3. The NHE system is composed of a single protein and is believed to participate in intracellular pH regulation. Furthermore, our studies indicate that at least one isoform of the electroneutral Naf/K+/2C1- cotransporter (NKCC) is present in human chondrocytes. There are no obvious variations in the relative expression of NHE isoforms or NKCC between healthy and arthritic cartilage. Our data suggests that chondrocytes from arthritic cartilage may adapt to changes in their environmental sodium concentration through variations in ENaC protein levels. ENaC is also likely to serve as a major sodium entry mechanism, a process that, along with cytoskeletal proteins, may be part of mechanotransduction in cartilage.
Open Access
lntraocular neovascularization
(Murcia : F. Hernández, 1999) Yoshida, A.; Yoshida, S.; Ishibashi, T.; Inomata, H.
An important character of the eye is transparency, so intraocular neovascularization, which is fragile and likely to result in hemorrhage, would cause a functional disorder of the eye and contribute to loss of vision associated with such diseases as retinopathy of prematurity, diabetic retinopathy, retinal vein occlusion, and age-related macular degeneration. Recently interest in the mechanisms of intraocular neovascularization has increased, and the mechanisms have been gradually elucidated using several in vitro and in vivo angiogenesis models. Blood vessels in the eye are composed of, and surrounded by, various types of cells that produce multiple factors. Neovascularization is regulated by complex interactions among these angiogenic factors, angiostatic factors, and adhesion molecules, and some of these angiogenesis-related molecules have also been suggested as new targets for novel therapeutic agents of intraocular neo-vascularization. This review focuses on in vivo representative angiogenesis models of the corneal pocket model and the model of oxygen-induced retinopathy, and discusses the role of some angiogenesisrelated factors and adhesion molecules in intraocular neovascularization.
Open Access
Heterotopic neogenesis of skeletal muscle induced in the adult rat diaphragmatic peritoneum. Ultrastructural and transplantation studies
(Murcia : F. Hernández, 1999) Drakontides, A.B.; Danon, M.J.; Levine, S.
During the course of a mild chemical peritonitis, new skeletal muscle fibers develop and persist over a twelve-month interval in the diaphragmatic peritoneum. Light and electron microscopic studies revealed that the ectopic fibers developed from myoblasts and myotubes to fully differentiated muscle cells in the same manner as normally situated skeletal muscle. The ectopic fibers were separated from the intrinsic muscle by dense connective tissue and an elastic lamina. Diaphragms taken from normal rats and transplanted to the omentum of isogeneic recipients also developed skeletal muscle neogenesis in the same ectopic location as in the normal diaphragm. Satellite cells, reactive fibroblasts in the peritoneum, mesenchymal stem cells or blood-borne myoblast precursor cells could be the source of these ectopic muscle fibers. The results of the present studies, however, cannot provide conclusive evidence for the origin of the new muscle fibers. Regardless of their source, the methods employed may represent a unique model for the development and prolonged maintenance of skeletal muscle fibers in a heterotopic location in vivo.
Open Access
Size and degeneration increase in herring bodies during aging in hamsters
(Murcia : F. Hernández, 1999) Navarro, A.; Tolivia, J.; Alvarez-Uría, M.
The hypothalamo-neurohypophysial tract of young, adult and aged male hamsters was studied at lateral and ventral regions of hypothalamus by means of electron microscopy. Neurosecretory swelling axons (Herring bodies) were usually found as classically described containing abundant neurosecretory granules, mitochondria, few microtubules and profiles of smooth endoplasmic reticulum in al1 groups of age. However, in aged hamsters, starting at 18-month-old subjects, we observed that the size of some neurosecretory axons was highly increased. Autophagic and degenerative features were seen in the larger ones. These data could suggest abnormal axonal storage or axonal transport blocked during aging. The implications in the role of hypothalamus- neurohypophysial system during aging are discussed.
Open Access
Effects of neurotensin and bombesin on the secretory and proliferative activity of regenerating rat adrenal cortex
(Murcia : F. Hernández, 1999) Hochol, A.; Markowska, A.; Meneghelli, V.; Jedrzejczak, N.; Majchrzak, M.; Nowak, M.; Nussdorfer, G.G.; Malendowicz, L.K.
Neurotensin (NT) and bombesin (BM)-like peptides are known to be involved in the regulation of the rat hypothalamo-pituitary-adrenal axis. By using selective NT- and BM-receptor antagonists (NT-A and BM-A, respectively) we investigated whether endogenous NT and BM-like peptides play a role in the control of rat adrenal secretion and growth during enucleation-induced regeneration. At day 5 of regeneration, NT-A did not affect the plasma concentrations of aldosterone (PAC) and corticosterone (PBC), but at day 8, it raised both PAC and PBC over the respective baseline value; the simultaneous administration of NT abolished this effect of NT-A. BMA did not alter PAC and PBC at day 5 of regeneration, while at day 8 it enhanced PBC, an effect reversed by BM. NT-A did not alter mitotic index, and BM-A lowered it at both day 5 and day 8 of regeneration, an effect suppressed by the simultaneous administration of BM. Collectively, these findings allow us to draw the following conclusions: 1) endogenous NT and BM-like peptides influence adrenocortical regeneration in rats; 2) NT exerts a tonic inhibitory action on both aldosterone and corticosterone secretion, without affecting cellproliferation rate; and 3) BM-like peptides exert a tonic suppressive effect on corticosterone production, coupled with a clear-cut stimulating effect on cell proliferation.
Open Access
Sodium 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.
Open Access
Tumor DNA circulating in the plasma might play a role in metastasis. The hypothesis of the genometastasis
(Murcia : F. Hernández, 1999) García-Olmo, Dolores C.; Ontañon, J.; Martinez, E.
Background: Clinical and experimental observations suggest that more than one pathway might be involved in the development of metastases. In the present study, we examined the presence of tumor DNA in plasma using an experimental model in which tumor cells were modified with a genome-associated tag. We also investigated whether plasma of tumor-bearing rats had any effect on cultured cells and healthy animals. Methods: Transfected cancer cells (DHDlK12-PROb stably transfected with pCDNA3.1CAT.) were injected subcutaneously into the chest of BD-IX rats. Animals were divided into ten groups according to the time between injection of tumor cells and euthanasia. Prior to euthanasia (2-14 week), blood samples were collected by cardiac puncture. To detect circulating tumor cells and CAT-encoding DNA in plasma, we performed PCR with nested primers. Fifty samples of plasma were chosen at random to supplement the medium of fifty cultures of DHD cells for 10-12 days. PCR for the detection of CAT DNA in cells was performed approximately one to two months later. Four healthy rats received an intraperitoneal injection of plasma from a tumor-bearing rat five times at week for 4 to 6 weeks. Animals were sacrificed and samples of liver, kidney, spleen, omentum, blood and lung were processed by PCR for the detection of CAT DNA. Results: Detection of CAT DNA in plasma was slightly more frequent than in the buffy-coat fraction. All surviving cultures that had been supplemented with plasma were positive at some point for CAT DNA. In all four healthy animals injected with plasma of tumor-bearing rats, the marker gene for CAT was found in extracts of lungs. Conclusion: Our present observation lead us to propose the following hypothesis. Metastases might develop as a result of transfection of susceptible cells in distant target organs with dominant oncogenes that are present in the circulating plasma and are derived from the primary tumor.
Open Access
Antisense 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.
Open Access
The possible role of colligin, HSP47, a collagen-binding protein, in the pathogenesis of human and experimental fibrotic diseases
(Murcia : F. Hernández, 1999) Razzaque, M.S.; Taguchi, T.
Colligin or heat shock protein 47 (HSP47) is a stress protein that resides in the endoplasmic reticulum and is thought to participate in intracellular processing, folding, assembly and secretion of procollagens. Irrespective of the tissue site and organ, induction of colliginlHSP47 expression is always noted during the process of fibrosis, particularly in and around the fibrotic lesions in both humans and experimental models. Its expression is highly tissue- and cell-specific, and restricted to mostly phenotypically altered collagenproducing cells. These observations suggest that upregulation of this collagen-specific chaperone-colliginl HSP47 may play an important role in the subsequent fibrotic process, possibly by regulating increased synthesis/assembly of collagens.
Open Access
EGF receptor signaling in prostate morphogenesis and tumorigenesis
(Murcia : F. Hernández, 1999) Kim, H.G.; Kassis, J.; Souto, J.C.; Turner, T.; Wells, A.
The growth and differentiation of the prostate gland are largely dependent on extracellular signaling factors. In addition to androgens, many polypeptide growth factors function through autocrine or paracrine networks. The paracrine interaction between stromal and epithelial cells is critical for androgen regulation, morphogenesis, epithelial cell proliferation, and secretory differentiation. Efforts to identify the essential growth factors and studies on their effects have been prompted by the fact that prostate cells in culture need substances other than androgens for proliferation. In this context, transforming growth factor-a and epidermal growth factor, among others, have been studied extensively. Recent advances have suggested that these EGF receptor (EGFR) ligands play roles not only during glandular development but also during neoplastic transformation and tumor progression. The cell responses most relevant to the role of this receptor signaling are both mitogenesis and cell motility. The aim of the review is to provide an overview of current knowledge about EGFR and its ligands in the organogenesis and tumorigenesis of the prostate gland.
Open Access
Novel 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.
Open Access
Bone 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.
Open Access
Alveolar cells in cyclophosphamide-induced lung injury. II. Pathogenesis of experimental endogenous lipid pneumonia
(Murcia : F. Hernández, 1999) Sulkowski, S.; Sulkowska, M.
An ultrastructural and histological study was made to analyse the structural and cellular features of the pulmonary lesions produced in Wistar rats by intraperitoneal (i.p.) administration of cyclophosphamide (two i.p. doses of 150 mg CP/1 kg bwtl m1 PBS). Rats exposed to cyclophosphamide (CP) developed a condition whose morphological picture corresponded to endogenous lipid pneumonia andlor pulmonary alveolar proteinosis-like changes. Damage to the endothelium and neutrophil accumulation in lung vascular bed were found to be potential initiators of endogenous lipid pneumonia-type changes. The possibility of the evolution of the acute lung injury into endogenous lipid pneumonia-type changes and into alveolar proteinosislike changes was demonstrated. The results of the study supplement the existing theories of pulmonary alveolar proteinosis pathogenesis.
Open Access
Fine structure of the retina of black bass, Micropterus salmoides. Centrarchidae, Teleostei
(Murcia : F. Hernández, 1999) García, M.; De Juan, J.
The structure of light- and dark-adapted retina of the black bass, Micropterus salmoides has been studied by light and electron microscopy. This retina lacks blood vessels at all levels. The optic fiber layer is divided into fascicles by the processes of Miiller cells and the ganglion cell layer is represented by a single row of voluminous cells. The inner nuclear layer consists of two layers of horizontal cells and bipolar, amacrine and interplexiform cells. In the outer plexiform layer we observed the synaptic terminals of photoreceptor cells, rod spherules and cone pedicles and terminal processes of bipolar and horizontal cells. The spherules have a single synaptic ribbon and the pedicles possess multiple synaptic ribbons. Morphologically, we have identified three types of photoreceptors: rods, single cones and equal double cones which undergo retinomotor movements in response to changes in light conditions. The cones are arranged in a square mosaic whereas the rods are dispersed between the cones.
Open Access
Circadian and seasonal changes of synaptic bodies in different parts of the rabbit pineal gland
(Murcia : F. Hernández, 1999) Martínez Soriano, F.; Hernandez-Gil de Tejadal, T.; Lopez Bigorra, M.; Ballester Carmona, S.; Vollrath, L.
In the mammalian pineal gland, synaptic bodies (SBs) are poorly understood organelles. Previous studies in rabbits have shown that the organelles are rather heterogeneous in shape, are few in number during the day and increase in number at night. No studies are currently available on seasonal changes in this species and it is unknown whether the biological rhythms are identical in the proximal, intermediate and distal parts of the elongated pineal. To this end, a study was made of 84 rabbits kept under natural lighting conditions to examine numerical variations of the different types of SBs in the proximal, intermediate and distal regions of pineal glands procured at different timepoints of a 24- hour cycle and in each of the four annual seasons. In the present study, rod-like, sphere-like, ovoid, rectangular and triangular SB profiles were distinguished; the first two types being the most abundant. In addition to the well-known circadian changes, with low numbers of SB profiles during the day and high numbers at night, we found pronounced season-related differences as well as differences related to pineal regions. In autumn and winter, nighttime SR profile numbers were significantly higher than in spring and summer. With respect to regional differences it was found that the amplitude of the circadian rhythm increased in a proximo-distal direction in the gland. In autumn the strongly enhanced nocturnal increase was restricted to the distal region of the gland, whereas in winter it was seen in both the distal and the intermediate regions. The regional differences are probably related to the fact that the postganglionic sympathetic fibres, which regulate pineal function, enter the gland distally and proceed rostrally to the proximal region. Taken together, the results show that day- and nightlength are structurally coded in the pineal gland by means of SB numbers. Provided the SBs of the mammalian pineal gland are involved in synaptic processes, the results suggest that synaptic processes are enhanced at night as well as in autumn and winter.
Open Access
Regulation mechanisms for the heterodimeric transcription factor, PEBP2lCBF
(Murcia : F. Hernández, 1999) Bae, S.C.; Ito, Y.
Members of the new PEBP2 (Polyomavirus Enhancer Binding Protein 2) family of heterodimeric transcriptional regulatory protein are composed of two subunits, a and B. One of the genes encoding the a subunit, AMLlIPEBP2aB, was identified at the breakpoints of various chromosome translocations, including t(8;21) and t(12;21) associated with acute myeloid leukemia and acute lymphoblastic leukemia, respectively. The gene encoding the B subunit (PEBP2flCBFB) was also shown to be the target of the inversion of chromosome 16, another chromosomal anomaly associated with acute myeloid leukemia. Targeted disruption of either the AmlllPebp2aB or PebpZflICbfb gene resulted in strikingly similar phenotypes such as lack of definitive hematopoiesis of the fetal liver and accompanying hemorrhage of the central nervous system. These observations suggest that both a and l3 subunits of PEBP2 are indispensable for its in vivo function. However, the heterodimerization of the a and B subunit does not seem to occur readily suggesting that their capacity to associate might be an important rate limiting step in PEBP2 site-dependent transcription regulation. In this review, we concentrate on the possible regulatory mechanisms of PEBP2 activity in relation to leukemogenesis.
Open Access
Neuronal anomalies and normal muscle morphology at the hypomotile ileocecocolonic region of patients affected by idiopathic chronic constipation
(Murcia : F. Hernández, 1999) Faussone-Pellegrini, M.S; Infantino, A.; Matini, P.; Masin, A.; Mayer, B.; Lise, M.
Patients suffering from idiopathic slowtransit chronic constipation have a delayed colonic transit referable to a decrease or loss of propagating contractions. Myogenic andlor neural mechanisms have been implicated in the pathophysiology of this dysfunction and neuronal abnormalities have been described at the ascending, descending and sigmoid colon. The morphology and motile behaviour of the ileocecocolonic region, which in healthy subjects regulates cecum filling and emptying, have never been investigated in such disease. Therefore, we endoscopically ascertained whether a motility impairment was present at these junctional areas and neither spontaneous nor provoked occlusive contractions were found at the cecocolonic junction. Light and electron microscope examination of the entire colon revealed apparently normal features of neurons, smooth muscle cells and interstitial cells of Cajal, while immunohistochemistry and quantitative analysis demonstrated neuronal anomalies at the junctional areas. These anomalies consisted of low total neuron density and significantly few VIP-immunoreactive neurons at the two enteric plexuses, significantly few NOS-immunoreactive neurons at t h e myenteric plexus and significantly more NOS-immunoreactive neurons at the submucous plexus. These findings exclude a myopathy and demonstrate the existence of a neuropathy. In particular, the presence at the ileocecocolonic region of few VIP- and NO-producing neurons suggests that there might be a reduced VIP and NO production which may result in a compromised relaxation andlor onset of propagating contractions, slowing down bolus transit. The presence at the proximal colon of such an abnormality might explain why left colectomy andlor cecorectal anastomosis are unsuccessful in patients with this disease.
Open Access
Differential requirements of naive and memory T cells for CD28 costimulation in autoimmune pathogenesis
(Murcia : F. Hernández, 1999) Perrin, P.J.; Lovett-Rackez, A.; Phillips, S.M.; Racke, M.K.
Experimental autoimmune encephalomyelitis (EAE) is the most extensively studied animal model of the human disease multiple sclerosis (MS). In EAE, CNS demyelination is induced by immunization with myelin proteins or adoptive transfer of myelin-reactive C D ~ +T cells. Since the antigen specificity of the immune response believed to be responsible for the pathology of MS is not well defined, therapies that target aspects of T cell activation that are not antigen specific may be more applicable to the treatment of MS. As a result, understanding the role of costimulatory molecules in the activation of nai've and memory T cells has become an area of extensive investigation. Naive T cells require two signals for activation. Signal one is provided by engagement of the T cell receptor (TCR) with MHCIpeptide complexes and provides antigen specificity to the immune response. The second signal, termed costimulation, is usually provided by B7 molecules on APC to CD28 molecules expressed on T cells and is antigen-independent. This review will discuss our current understanding of costimulation in the induction and perpetuation of EAE, as well as the potential of costimulaton blockade in the treatment of MS.