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Biomedical subjects

Z Varga

Publications and source records attributed to Z Varga.

At least 91 records · Page 5Linked to original sources
PubMed1996

Effect of acetylcholine on the electrophysiology and proliferative response of human lymphocytes.

Using the patch-clamp technique, we determined that 1-15 mM extracellular acetylcholine reduced whole-cell n-type K+ currents in human peripheral blood lymphocytes and accelerated their inactivation. The percentage increase in K+ channel inactivation rate and the degree of drug induced block were independent of membrane potential. In flow cytometric membrane potential measurements with the oxonol dye similar doses of acetylcholine depolarized the lymphocyte population. Both acetylcholine induced K+ channel block and depolarization fully developed within 2 minutes. The depolarizing and K+ channel blocking effects of acetylcholine are in concert. [3H]thymidine incorporation experiments proved that the proliferative response of PHA stimulated peripheral blood lymphocytes was decreased by increasing concentrations of acetylcholine in the 1-50 mM range.

Acetylcholine↗
PubMed1996

[Primary cerebral T-cell lymphoma].

The authors describe a case of primary cerebral T-cell lymphoma observed in a 68-year-old man. The patient suffered from disseminated follicular carcinoma of the thyroid and the clinical picture has been dominated by neurological symptoms of presumed metastatic origin. Primary cerebral lymphoma was discovered at autopsy. Histologically, it proved to be a high-grade malignant pleomorphic non Hodgkin's lymphoma whose T-cell lineage was confirmed by immunohistochemistry. The patient did not manifest any congenital or acquired immune deficiency. There were neither cerebral metastases of the thyroid cancer nor any evidence for extracranial involvement by a lymphoma. Providing a brief literature review of cerebral T-cell lymphomas, the authors discuss some major traits of this exceptional form of lymphoid neoplasia of the central nervous system. Differential diagnostic and theoretical implications raised by cerebral lymphomas as second malignant tumors synchronously or metachronously associated with other malignant diseases are envisaged.

Adenocarcinoma, Follicular↗
PubMed1996

Apoptosis is triggered by the cyclic AMP signalling pathway in renal mesangial cells.

Glomerular mesangial cells are regarded as specialized smooth muscle cells located within the renal glomeruli and fulfilling important functions in glomerular physiology and pathophysiology. Here, we report that activation of the cyclic AMP signalling pathway by dibutyryl cyclic AMP, forskolin, or the beta 2-adrenergic receptor agonist salbutamol results in induction of apoptosis in mesangial cells. Activation of the apoptotic programme results in DNA fragmentation which is visible for most forms of apoptosis and is paralleled by enrichment of cytosolic DNA/histone complexes, an increasing number of cellular 3'-OH-fragmented DNA ends and typical nuclear chromatin condensation. Induction of apoptosis was found to be dependent on translation and independent of nitric oxide synthase activity.

Adrenergic beta-Agonists↗
PubMed1996

The effect of juglone on the membrane potential and whole-cell K+ currents of human lymphocytes.

Using flow cytometric membrane potential measurements with the oxonol dye, we determined that 5.7-57 microM juglone depolarizes human lymphocytes in a dose dependent manner. The depolarizing effect of juglone was verified by patch-clamp. Juglone decreased whole-cell n-type K+ currents in human peripheral blood lymphocytes and accelerated inactivation; however, it did not influence the kinetics of activation of the K+ conductance. The percentage increase in K+ channel inactivation rate and the degree of drug induced block was independent of membrane potential, K+ channel block by juglone fully developed within 4 minutes and was not removable by washing with drug free extracellular solution. Blocking of n-type K+ channels by juglone is in concert with its depolarizing effect on human lymphocytes.

Cytotoxins↗
PubMed1996

Tubular adenoma of the choroid plexus: evidence for glandular differentiation of the neuroepithelium.

A case of tubular adenoma arising in the right ventricular choroid plexus of a 4-month-old boy is described. A basic pattern of neoplastic glandular epithelium and lack of papillary architecture distinguished this tumor from a papilloma. Coexpression of S -100 protein, transthyretin and cytokeratin identified the neoplastic cells as being of choroid plexus origin. Immunohistochemical detection of MIB-1 showed a proliferation rate (16%) similar to adenomas in more conventional locations, but not encountered in benign brain tumors. In situ detection of DNA-derived oligonucleosomal fragments by TUNEL analysis, on the other hand, detected apoptotic activity in 5-8% of tumor cells. The indolent course of the disease in the present case, thus, might suggest a compensatory elimination of proliferating cells by apoptosis. This possibly points to mechanisms of neoplastic transformation different from those involved in choroid plexus papillomas.

Adenoma↗
PubMed1996

The standard isoform of CD44 is preferentially expressed in atypical papillomas and carcinomas of the choroid plexus.

Isoforms of the CD44 adhesion molecule have been assigned a pivotal role in tumor invasion and metastasis. CD44 splice variants may be selectively expressed in various normal and neoplastic tissues. We investigated immunohistochemically the presence of the standard (H) and two variant (v3, v6) isoforms of the CD44 molecule in a series comprising 13 choroid plexus papillomas (WHO grade I) and 8 carcinomas (WHO grade III). In the papilloma group, 5 tumors showed variable cellular pleomorphism and foci of infiltrative growth, and were tentatively classified as atypical papillomas. Autopsy specimens of normal pediatric and adult choroid plexus were used as control. Western-blot analysis of CD44H was carried out on 4 carcinomas, 1 papilloma and on normal choroid plexus. The proliferation rate was assessed by MIB-1 immunoreactivity. The normal choroid plexuses and 9 papillomas were negative for the standard as well as the variant CD44 molecules investigated. Four atypical papillomas and 5 carcinomas expressed CD44H. CD44v3 and CD44v6 were only detected in one of the atypical papillomas also positive for CD44H. These data indicate that CD44H is preferentially expressed on atypical papillomas and carcinomas and may correlate with the infiltrative growth of these tumors.

Adolescent↗
PubMed1996

MIB-1 immunoreactivity reveals different labelling in low-grade and in malignant epithelial neoplasms of the choroid plexus.

MIB-1 immunohistochemistry was carried out on a retrospective biopsy series of epithelial choroid plexus neoplasms in order to assess the proliferation rate of tumour cells. The material included 14 cases of papilloma (WHO grade I) and five cases of carcinoma (WHO grade III). There was one recurrent tumour in the papilloma group, while three patients with carcinoma experienced recurrence. Choroid plexus obtained at autopsy from paediatric and adult patients with unrelated diseases served as control. The average MIB-1 labelling index of choroid plexus papillomas was 3.7%, while that of carcinomas was 14%, and that of normal choroid plexus was 0.02% to 0.06%. The age and sex of the patients as well as the tumour localization were not found to influence MIB-1 reactivity. The labelling index of recurrent lesions was not significantly different from that of the corresponding primary tumours. High MIB-1 labelling indices were associated with less favourable post-operative outcome in choroid plexus carcinomas and in one papilloma with atypical histology. However, most tumours with atypical histological features did not exhibit distinctive MIB-1 labelling indices. Analysis of growth fraction by MIB-1 immunohistochemistry may prove a useful ancillary method for assessing the malignant potential of choroid plexus neoplasms.

Adolescent↗
PubMed1995

[Dysembryoplastic neuroepithelial tumor].

The dysembryoplastic neuroepithelial tumor is a benign central nervous system neoplasm of children and young adults manifesting almost exclusively in complex partial seizures. The authors report the case of an 8-year-old boy presenting with characteristic clinical and radiologic features who subsequently underwent surgery. Light microscopic, immunohistochemical and ultrastructural traits of the tumor are described demonstrating pluripotential differentiation of tumor cells and architectural features suggesting a dysontogenic lesion. A brief literature review on the biology and histologic diagnosis of the dysembryoplastic neuroepithelial tumor is provided. Although this uncommon tumor accounts for only a minority of intracranial neoplasms, its pathogenetic role has to be considered in the differential diagnosis of temporal lobe epilepsies. This is the first report on this recently described, rare neoplastic condition in Hungary.

Brain Neoplasms↗
PubMed1995

Development and migration of olfactory neurones in the nervous system of the neonatal opossum.

The neonatal opossum (Monodelphis domestica) was used to assess how different populations of cells are generated in the olfactory region, and how they migrate along pathways to the central nervous system. Developing nerve cells were immunocytochemically labelled using antisera directed against two specific markers of olfactory receptor neurones: olfactory marker protein (OMP) and the dipeptide carnosine. In new-born opossums both carnosine and OMP are already co-expressed in primary olfactory neurones and in those axons that extend towards the olfactory bulb. Expression of these markers in olfactory receptor neurones during the first postnatal days reflects the advanced developmental state of this system compared to other regions of the central nervous system (such as the cortex and cerebellum), which are highly immature and less developed in comparison with those of new-born rats or mice. A second, distinct population of carnosine/OMP expressing cells was also identified during the first postnatal week. These neurones were present as clusters along the olfactory nerve bundles, on the ventral-medial aspect of the olfactory bulb and in the basal prosencephalon. The distribution of this cell population was compared to another group of well characterized migratory neurones derived from the olfactory placode, which express the decapeptide GnRH (Gonadotropin-releasing hormone, also known as LHRH). GnRH was never co-localized with carnosine/OMP in the same migratory cells. These observations show that distinct cell populations arise from the olfactory placode in the neonatal opossum and that they migrate to colonize the central nervous system by following common pathways.

Animals↗
PubMed1995

[Symptomatic glial cysts of the pineal gland: report of two cases and review of the literature].

Referring to two individual cases, the authors review clinical, radiological and histological features of benign glial cysts of the pineal gland. Both patients were young females with aggravating headaches and with convulsions in one case. Symptoms were referable to a space-occupying cystic mass of the pineal gland. On histology, both lesions proved to be non neoplastic cysts without an epithelial lining. Their histogenesis and low growth potential were reinforced by immunohistochemical analysis of pineal antigens and proliferation markers. Glial cysts of the pineal gland are not infrequent, but symptomatic occurrences are exceptional. Most glial cysts are of dysontogenic or degenerative origin. Sometimes, however, the role of hormonal influences or paraneoplastic factors must be considered. Symptoms caused by glial cysts of the pineal gland are non-specific and radiologic imaging technics may contribute little to etiologic diagnosis. Pineal cysts are curable by surgical resection or stereotactic decompression. Whatever the diagnostic approach, emphasis must be laid on the histologic examination in order to avoid unnecessarily aggressive treatment.

Adolescent↗
PubMed1995

[Malignant melanoma evolving inside a cerebral epidermoid cyst].

A case of malignant melanoma arising in a cerebral epidermoid cyst is reported. The neoplasm presented as a rapidly enlarging mass in the left temporal lobe of a 52-year-old woman. The authors provide histological evidence for the provenance to tumour cells from the epithelial lining of the cyst. The melanocytic nature of the neoplasm was demonstrated by immunohistochemistry and electron microscopy. Post mortem examination ruled out the possibility of metastatic origin. The occurrence of intracranial epidermoid cysts and malignant melanoma, their eventual association with maldevelopmental processes or neoplasia are briefly reviewed. Although linked together histogenetically, epidermoid cysts and melanoma do not seem to be involved by common pathogenetic processes. To the best of our knowledge, no previous reference is available on malignant transformation of melanocytes in an epidermoid cyst.

Brain Diseases↗
PubMed1995

Synthesis of new pseudodisaccharide aminoglycoside antibiotics from carbohydrates.

Novel pseudodisaccharide-type aminocyclitol antibiotic models, built up from D-arabinose, D-ribose, D-glucosamine, L-ristosamine and L-acosamine have been synthesized by the glycosylation of suitably protected (azido)deoxyinosose aglycones derived by the Ferrier carbocyclic ring transformation of carbohydrate precursors. An alternative approach to related pseudodisaccharides, based on the Ferrier carbocyclization of reducing disaccharides, has also been elaborated. This latter method extends the scope of the Ferrier reaction, by demonstrating that acid-labile 2-deoxydisaccharides can also be readily transformed into the corresponding pseudodisaccharides under the slightly acidic conditions of this ring-transformation.

Aminoglycosides↗
PubMed1995

Melanotic papilloma of the choroid plexus: report of a case with implications for pathogenesis.

A case of pigmented choroid plexus papilloma removed from the 4th ventricle of a 43-year-old man is reported. The tumor showed histologic, immunophenotypic, and ultrastructural features of neoplastic choroid plexus epithelium. There was no evidence of melanosomal activity or neurosecretion. The pigment consisted of an intimate association of lipofuscin and neuromelanin, indicating autocatalytic peroxydation of the former as a putative way of melaninogenesis. The low proliferation rate of the tumor together with immunohistochemical evidence of inactivation of p53 protein suggest a delayed turnover of neoplastic cells as a possible source of lipofuscin accumulation.

Adult↗
PubMed1994

[Central neurocytoma: a rare tumor of the cerebral ventricles].

The case of a 33-year-old man is presented, who acutely developed disturbance of consciousness, symptoms of raised intracranial pressure and unilateral neurological signs. The underlying lesion was a hemorrhagic tumor located in the left lateral ventricle. On histological examination, the surgically resected mass proved to be a central neurocytoma, a benign neuroectodermal neoplasia. Difficulties in differential diagnosis by imaging technics and histopathology render this unusual lesion worth publishing. To the best of our knowledge, no similar report on this recently described rare entity has been published in Hungary.

Adult↗
PubMed1994

Repair of connections in injured neonatal and embryonic spinal cord in vitro.

A remarkable preparation for studying development and repair is the CNS of the newborn opossum which, removed in its entirety, survives in culture for more than 1 week. In suitable medium, cells continue to divide, mature and reflex activity is maintained. Moreover, nerve fibers grow rapidly, reliably and extensively across lesions made in the spinal cord. Restoration of conduction has been demonstrated by recording electrically; labeled fibres have been observed directly by light and electron microscopy as they traverse the lesion. Similar experiments have also been made in embryonic (E15) rat CNS in culture. Open questions concern the identity of the fibers that traverse the lesion and the specificity of connections that they make with targets. We are now also analysing mechanisms that favor repair in younger opossums and that prevent it in their older siblings. Of particular interest are oligodendrocytes and myelin that start to appear at about 8-9 days after birth.

Animals↗
PubMed1994

GnRH neurons and other cell populations migrating from the olfactory neuroepithelium.

Cell migration from the olfactory neuroepithelium to the brain has been widely studied during vertebrate development. Immunocytochemical analysis has revealed that many of the migrating cells contain GnRH (Gonadotropin-Releasing Hormone). The GnRH positive cells migrate from the medial olfactory placode, steam along the nasal septum, cross the basal forebrain and reach the hypothalamic and septal areas from where they control the release of hypophyseal gonadotropic peptides. A peculiar feature of these cells is that they start expressing GnRH during migration. We have analysed the presence of immunoreactivity for peptides typically expressed in olfactory neurones, along the migratory pathway followed by GnRH neurones. We have used polyclonal antibodies raised against carnosine and olfactory marker protein (OMP), and performed double immunolabelling on mouse embryos and on early neonatal Brazilian opossum (Monodelphis domestica) tissues. Beside the GnRH neurones we observed other migrating cells along the pathway traced by olfactory terminal and vomeronasal nerves. Most of these cells co-express carnosine and OMP. The carnosine/OMP migrating cells are detectable in later developmental stages than GnRH neurones. GnRH neurones do not express either OMP or carnosine. By keeping in culture explants of the brain together with the olfactory region from newborn opossums, we have shown that it is possible to obtain the migration of the different populations in vitro. Moreover the GnRH cells are co-distributed, but different from those expressing olfactory markers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗