Zoltán Mészár

Publications of Zoltán Mészár

• The lateral hypothalamic parvalbumin-immunoreactive (PV1) nucleus in rodents.

  Authors: Zoltán Mészár, Franck Girard, Clifford B Saper, Marco R Celio

  The Journal of comparative neurology. 03/2012; 520(4):798-815.

  In the lateral hypothalamus, groups of functionally related cells tend to be widely scattered rather than confined to discrete, anatomically distinct units. However, by using parvalbuminIn the lateral hypothalamus, groups of functionally related cells tend to be widely scattered rather than confined to discrete, anatomically distinct units. However, by using parvalbumin (PV)-specific antibodies, a solitary, compact cord of PV-immunoreactive cells (the PV1-nucleus) has been identified in the ventrolateral tuberal hypothalamus in various species. Here we describe the topography, the chemo-, cyto-, and myeloarchitectonics, and the ultrastructure of this PV1-nucleus in rodents. The PV1-nucleus is located within the ventrolateral division of the medial forebrain bundle. In the horizontal plane, it has a length of 1 mm in mice and 2 mm in rats. PV-immunoreactive perikarya fall into two distinct size categories and number (~800 in rats and ~400 in mice). They are intermingled with PV-negative neurons and coarse axons of the medial forebrain bundle, some of which are PV-positive. Symmetric and asymmetric synapses, as well as PV-positive and PV-negative fiber endings, terminate on the perikarya of both PV-positive and PV-negative neurons. PV-positive neurons of the PV1-nucleus express glutamate, not γ-aminobutyric acid (GABA), the neurotransmitter that is usually associated with PV-containing nerve cells. Although we could not find evidence that PV1 neurons express either catecholamines or known neuropeptides, they sometimes are interspersed with the fibers and terminals of such cells. From its analogous topographical situation, the PV1-nucleus could correspond to the lateral tuberal nucleus in humans. We anticipate that the presence of the marker protein PV in the PV1-nucleus of the rodent hypothalamus will facilitate future studies relating to the connectivity, transcriptomics, and function of this entity.

• Hyaluronan accumulates around differentiating neurons in spinal cord of chicken embryos.

  Authors: Zoltán Mészár, Szabolcs Felszeghy, Gábor Veress, Klára Matesz, György Székely, László Módis

  Brain research bulletin. 04/2008; 75(2-4):414-8.

  One major component of the extracellular matrix is hyaluronan (HA) which is thought to play a crucial role in the development of different organs including the central nervous system (CNS). HA isOne major component of the extracellular matrix is hyaluronan (HA) which is thought to play a crucial role in the development of different organs including the central nervous system (CNS). HA is bound by specific receptors, CD44 and RHAMM, depending on cell types of CNS. However, data are lacking on the relation of HA to different cell populations in developing CNS. To provide new data about the co-localization of HA with the various cellular structures of the developing spinal cord, we studied the distribution pattern of hyaluronan in chicken embryos at Hamburger-Hamilton (HH) stages 8-39. A biotinylated HA-binding complex was used in combination with immunohistochemistry for proliferating and differentiating neurons. The intensity of the HA signal was determined by digital densitometry from histological sections. We found three mediolaterally oriented layers in the HA distribution pattern in stage HH23: (1) a moderate HA signal was detected in the ventricular zone; (2) strong HA accumulation was measured around Lim1,2-expressing cells (differentiating neurons) and early MNR2-expressing neurons (early motoneurons), corresponding to the intermediate zone; (3) a strong pericellular HA reaction was found around the neurons of the marginal zone. Interestingly, the peripheral nerves did not show HA signals. These findings suggest a crucial role of HA during neuronal development. We propose that HA may be involved in cell migration and axonal growth in the developing spinal cord.

• The effect of vestibular nerve section on the expression of the hyaluronan in the frog, Rana esculenta.

  Authors: Gábor Halasi, Ervin Wolf, Tímea Bácskai, György Székely, László Módis, Zsuzsa M Szigeti, Zoltán Mészár, Szabolcs Felszeghy, Clara Matesz

  Brain structure & function. 01/2008; 212(3-4):321-34.

  Following postganglionic lesion of the eighth cranial nerve, the changes in the expression of hyaluronan (HA), one of the extracellular matrix macromolecules, were examined in the medial (MVN) andFollowing postganglionic lesion of the eighth cranial nerve, the changes in the expression of hyaluronan (HA), one of the extracellular matrix macromolecules, were examined in the medial (MVN) and lateral (LVN) vestibular nuclei and in the entry or transitional zone (TZ) of the nerve in the frog. HA was detected in different survival times by using a specific biotinylated hyaluronan-binding probe. HA expression was defined by the area-integrated optical density (AIOD), calculated from pixel intensities of digitally captured images. During the first postoperative days the perineuronal net (PN), a HA-rich area around the neurons, was not distinguishable from the surrounding neuropil in the MVN and LVN, characterized by a bilateral drop of AIOD specifically on the operated side. From postoperative day 14 onwards AIOD increased whilst the PN reorganized. In contrast, the AIOD wobbled up and down bilaterally without any trend in the TZ. Statistical analysis indicated that AIOD changes in the structures studied ran parallel bilaterally presumably because of the operation. Our results demonstrated for the first time that (1) the lesion of the eighth cranial nerve is accompanied by the modification of AIOD reflected HA expression in the MVN, LVN and TZ, (2) different tendencies exist in the time course of AIOD in the structures studied and (3) these tendencies are similar on the intact and operated sides. Our findings may suggest an area dependent molecular mechanism of HA in the restoration of vestibular function.

• Distribution of hyaluronan in the central nervous system of the frog.

  Authors: Zsuzsa M Szigeti, Clara Matesz, George Szekely, Szabolcs Felszeghy, Timea Bácskai, Gábor Halasi, Zoltán Mészár, László Módis

  The Journal of comparative neurology. 07/2006; 496(6):819-31.

  The qualitative and quantitative distribution pattern of hyaluronan (HA), a component of the extracellular matrix (ECM), was studied in the frog central nervous system by using a highly specific HAThe qualitative and quantitative distribution pattern of hyaluronan (HA), a component of the extracellular matrix (ECM), was studied in the frog central nervous system by using a highly specific HA probe and digital image analysis. HA reaction was observed in both the white and the gray matter, showing a very intense staining around the perikarya and dendrites in the perineuronal net (PN). In the telencephalon, strong reaction was found in different parts of the olfactory system, in the pallium, and in the amygdala. In the diencephalon, intensive staining was found in the nucleus of Bellonci, the dorsal habenula, the lateral and central thalamic nuclei, and the subependymal zone of the third ventricle. In the mesencephalon, layers of optic tectum displayed different intensities, with the strongest reaction in layers B, D, F, 3, and 5. Other structures of the mesencephalon showed regional differences. The PN was especially intensively stained around the perikarya of the toral nuclei, the oculomotor and trochlear nuclei, and the basal optic nucleus. In the rhombencephalon, the granular layer of cerebellum, the vestibulocochlear nuclei, the superior olive, the spinal tract of the trigeminal nerve, and parts of the reticular formation showed the most intense reaction in the PN. In the spinal cord, considerable HA staining was found in the white matter and around the perikarya of motoneurons. The present study is the first description of the HA-positive areas of frog brain and spinal cord demonstrating the heterogeneity of HA distribution in the frog central nervous system.

• Az ép és kóros porcszövet változása in vitro kísérletekben = Alteration of normal and pathological cartilage tissue under in vitro conditions

  Authors: László Módis, Szabolcs Felszeghy, Levente Gáspár, Zoltán Mészár, Péter Molnár, Zoltán Szekanecz, Krisztina Szentesiné dr. Holló, Róza Zákány

  Pályázati ciklusunk 4 éve alatt az alábbi fontosabb eredményeket értük el: 1. A porcosodó "high-density" sejtkultúrákon végzett kísérleteinkkel kimutattuk, hogy az oxidatív stressz csökkenti aPályázati ciklusunk 4 éve alatt az alábbi fontosabb eredményeket értük el: 1. A porcosodó "high-density" sejtkultúrákon végzett kísérleteinkkel kimutattuk, hogy az oxidatív stressz csökkenti a képződő porc mennyiségét és az osztódó sejtek proliferációs képességét. Az oxidatív stressz a kalcineurin (PP2B) aktivitását és expresszióját csökkenti, míg az ERK és a Sox9 foszforilációja fokozódott. A kalcineurin farmakológiai inhibítora a ciklosporin hasonló hatással van a kultúrákra (Zákány és mtsai, 2005). 2. A mozaikplasztika továbbfejlesztése során humán műtéteket követően vett biopsziás minták hisztokémiai vizsgálatával igazoltuk, hogy a graft és host hialin porca és csontja az esetek döntő többségében tökéletesen fúzionál, a graft hialin porca csak néhány esetben alakul át rostos porccá (Hangody és mtsai, 2004; Hangody és Módis, 2006). Állatkísérletekkel igazoltuk, hogy a használt graft átmérőjének növelése stabilabb beépülést eredményez (Kordas és mtsai, 2006). Szövettani vizsgálataink során megerősítést nyert, hogy a mozaikplasztika lovakon is sikerrel végezhető (Bodó és mtsai, 2004). A donor-csatornák keletkezésével okozott komplikációk (vérzés) csökkentésére a PolyAktív biodegradábilis tömeszelőanyag jól alkalmazható (Bartha és mtsai, 2008). 3. Bizonyítottuk, hogy a makrofágok kulcsfontosságúak a RA patogenezisében. (Szekanecz és Koch, 2007). Rámutattunk az angiogenezist befolyásoló lehetőségekre az RA-terápiájában (Szekanecz és mtsai, 2005). | The following major new results were obtained: 1. Using chondrifying high density mesenchymal cell culture, we could detect that the oxidative stress decreases the chondrogenesis and the proliferation of chondrocytes. The oxidative stress decreases the activity and expression of calcineurin (PP2B), but the phosphorylation of ERK and Sox9 is elevated. Cyclosporine A, had the same effects on these cultures (Zákány et al, 2005). 2. In order to the further development of the mosaicplasty (MP), human biopsy samples taken after MP were analyzed histochemically. We demonstrated a complete fusion of the hyaline cartilage and bone of the donor and recipient areas in most cases. Exceptionally, the hyaline cartilage of the grafts is transformed to fibrocartilage (Hangody et al, 2004, Hangody and Módis, 2006). Using animal experiments, we came to the conclusion that the incorporation of the grafts can be improved by increasing the diameters of the grafts (Kordas et al, 2006). Clinical and histological investigations provided evidences about the successful application of MP also in horses (Bodo et al, 2004). To avoid the bleeding from the donor site, a biodegradable polymer material, polyactive, was successfully used for donor site filling in human MPs (Bartha et al, 2008). 3. We elucidated that macrophages can be regarded as possible target cells in the therapy of RA (Szekanecz and Koch, 2007). Therapy of RA by influencing angiogenesis is also discussed (Szekanecz et al, 2005).