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Biomedical subjects

S Virágh

Publications and source records attributed to S Virágh.

At least 19 recordsLinked to original sources
PubMed2002

Cutaneous lymphatic amyloid deposits in "Hungarian-type" familial transthyretin amyloidosis: a case report.

Multiple transthyretin (TTR) mutations have recently been identified and implicated in the development of familial systemic amyloidoses, but early diagnosis of these disorders is still largely unresolved. We investigated the presence and tissue distribution of TTR-derived amyloid in skin biopsies of a 59-year-old woman carrying the "Hungarian-type" mutation of TTR (Asp18Gly). Clinical symptoms involved severe central nervous system dysfunction without signs of polyneuropathy, also referred to as the "central form" of TTR-related systemic amyloidosis. Skin biopsy was also evaluated as a tool in order to diagnose this type of TTR amyloidosis. Biopsy samples were collected from the infra-axillary region. Light microscopy using Congo red and polarized light was used to diagnose amyloid deposits. Subsequently, electron microscopic analysis was performed to correlate the amyloid deposits with vicinal dermal structures. The amyloid class was determined by means of immunocytochemistry. TTR amyloid was primarily localized to lymphatic microvessels in the present case, whereas arterioles were devoid of TTR amyloid deposits. In addition, the well-known association of TTR amyloid with neural structures along the erector pilorum and around the sebaceous and serosal (sweat) glands was also evident. Electron microscopic analysis of amyloid deposits revealed characteristic amyloid fibrils that were irregular in shape, and exhibited a heterogeneous density and a random deposition pattern. Immunocytochemistry confirmed the cutaneous accumulation of TTR amyloid. In conclusion, amyloid deposits were abundantly present in the skin of a patient with "Hungarian-type" TTR amyloidosis; skin biopsy seems to be appropriate for the diagnosis of this disorder. We showed that besides the erector pilorum, sweat glands and nerve terminals, lymphatic microvessels are also severely infiltrated by TTR amyloid. Whether these pathological alterations can exclusively be found in "Hungarian-type" TTR amyloidosis should still be investigated. If such changes are not specific for the Asp18Gly mutation, they may be considered as diagnostic markers for "central" TTR amyloid disorders.

Amyloidosis↗
PubMed2001

Development of the myocardium of the atrioventricular canal and the vestibular spine in the human heart.

To establish the morphogenetic mechanisms underlying formation and separation of the atrioventricular connections, we studied the remodeling of the myocardium of the atrioventricular canal and the extracardiac mesenchymal tissue of the vestibular spine in human embryonic hearts from 4.5 to 10 weeks of development. Septation of the atrioventricular junction is brought about by downgrowth of the primary atrial septum, fusion of the endocardial cushions, and forward expansion of the vestibular spine between atrial septum and cushions. The vestibular spine subsequently myocardializes to form the ventral rim of the oval fossa. The connection of the atrioventricular canal with the atria expands evenly. In contrast, the expression patterns of creatine kinase M and GlN2, markers for the atrioventricular and interventricular junctions, respectively, show that the junction of the canal with the right ventricle forms by local growth in the inner curvature of the heart. Growth of the caudal portion of the muscular ventricular septum to make contact with the inferior endocardial cushion occurs only after the canal has expanded rightward. The atrioventricular node develops from that part of the canal myocardium that retains its continuity with the ventricular myocardium.

Antibodies↗
PubMed1997

Histological investigations of the nasal mucosa in human fetuses.

The adult nasal mucosa has been exposed to various external agents and selected physiological conditions. Changes in intranasal airflow influenced the morphological appearance of the mucosa. Studies of agents on the fetal mucosa and its development may contribute to better understanding of the morphology of the nasal mucosa. The authors studied the nasal mucosa of 20- to 26-week-old fetuses using light microscopy and scanning and transmission electron microscopy. Findings showed that this developing nasal mucosa took part in the production and movement of mucus in the nasal cavity.

Cartilage↗
PubMed1996

[Diagnostic problems of Wilson disease].

A family (three siblings) of Wilson's-disease is described. The authors review the pathogenesis, diagnostics, pathology and treatment of Wilson's-disease. The diagnostic difficulties are emphasised. The variety of liver lesions are demonstrated in the different grades of the disease. The importance of the early diagnosis is stressed.

Adolescent↗
PubMed1995

Dystrophin expression in the developing conduction system of the human heart.

Duchenne muscular dystrophy (DMD) is frequently associated with myocardial involvement. Dystrophin, the DMD protein, is found at the plasmamembrane of striated muscle fibers. Although dystrophin is missing in most or all muscle fibers of DMD patients, cardiac muscle is not as severely affected as skeletal muscle. Therefore it is of great importance to study the expression of dystrophin in normal cardiac muscle. We performed immunohistochemical studies and examined cardiac muscle of fetuses of 8 to 13 weeks of development on dystrophin expression. At these stages dystrophin is observed in the myocytes of the developing ventricular conduction system and in the atrial cardiomyocytes. Dystrophin was absent from the heart of a 12-week-old DMD fetus.

Antibodies, Monoclonal↗
PubMed1995

Formation of the tricuspid valve in the human heart.

BACKGROUND: Some of the problems concerning the origin of the inlet component of the definitive right ventricle were resolved in a previous study in which we showed it to be derived exclusively from the embryonic right ventricle. Questions remain, however, concerning the relative contributions of endocardial cushion tissue and myocardium to the definitive valvar apparatus guarding the right atrioventricular orifice and the origin of the valvar leaflets. METHODS AND RESULTS: The formation of the tricuspid valve was studied by scanning electron microscopic and immunohistochemical techniques. Concurrent with the development of the right atrioventricular connection, a myocardial ridge forms at the boundary between the atrioventricular canal and the embryonic right ventricle. It grows to become a myocardial gully that funnels atrial blood beneath the lesser curvature of the initial heart tube toward the middle of the right ventricle. Fenestrations in the floor of the gully create an additional inferior opening in the funnel, transforming its initial anterior rim into the septomarginal trabeculation. The septum formed by the fusion of the endocardial ridges of the outflow tract becomes myocardialized in its inferior portion to form, in part, the outlet septum and, in part, the supraventricular crest. The smooth atrial surface of the tricuspid valvar leaflets develops from endocardial cushion tissue. The leaflets become freely movable, however, only after delamination of the tension apparatus within the myocardium. The inferior and septal leaflets derive from the gully and the ventricular septum, their delamination being a single, continuous process. The antero-superior leaflet forms by delamination from the developing supraventricular crest. CONCLUSIONS: The leaflets of the tricuspid valve develop equally from the endocardial cushion tissues and the myocardium. The myocardium contributing to the valve comes from two sources, the tricuspid gully complex and the developing supraventricular crest. These findings facilitate the understanding of several congenital malformations.

Antibodies, Monoclonal↗
PubMed1995

Cell surface glycoconjugates and the extracellular matrix of the developing mouse embryo epicardium.

Cell surface glycoconjugates and the extracellular matrix (ECM) of the proepicardium and the developing epicardium were studied in early mouse embryos by light and electron microscopy with histochaemical and immunocytochaemical techniques. The extracardially located proepicardium consists of polarized mesothelial cells forming the proepicardial vesicles. These vesicles contain a fine proteoglycan network and an acellular ECM rich in hyaluronic acid. Membrane-bound glycoconjugates are shown with cuprolinic blue, alcian blue and ruthenium red on the apical (outer) cell surface, while fibronectin and laminin are present on the basal (luminal) cell surface. These membrane and matrix components of the proepicardium might be involved in specific attachment of proepicardial cells to the bare heart tube and might facilitate the initial migration of epicardial cells over the myocardial surface. In the cell coat of the cardiomyocytes of the bare heart tube the fibronectin and laminin are concentrated in patches. The formation of the epicardial covering is a rapid process, requiring only about 2 days (9-11 days) to ensheath the entire heart tube from the inflow to the outflow segment. The subepicardial matrix between the newly formed epicardial covering and myocardial layer is acellular at first, but contains a condensing proteoglycan network, membrane and matrix fibronectin, type IV collagen and laminin on the myocardial cell surface. The formation and the distribution of the subepicardial ECM show regional characteristics. The accumulating ECM forms wide subepicardial spaces and protuberances in the atrioventricular and interventricular sulci. The sulci of the heart seem to provide the optimum microenvironment for haematopoiesis and vasculogenesis. Haematopoietic islands and coronary vessel forerunners appear and concentrate in the regularly spaced surface protuberances. The vasculogenesis proceeds from the inflow to the outflow segment of the heart. The first blood capillaries appear in the sinoatrial sulcus of the 10-day embryo. By 11-13 days the subepicardial blood vessels form an interconnected network and establish the coronary artery orifices.

Animals↗
PubMed1993

[Bacillary angiomatosis].

In a 78 years old patient with chronic lymphoid leukemia, diabetes mellitus a cat scratch induced disseminated angiomatous papules were observed. In the lesions great number of bacilluses were observed with light -and electron microscope. As a result of antibiotic treatment the lesions regressed without trace. This opportunist infection resulting general symptoms as well, may be regarded as a cutaneous manifestation of immunodeficiency. The adequate antibiotic treatment depends on the exact diagnosis.

Aged↗
PubMed1993

Early development of quail heart epicardium and associated vascular and glandular structures.

As in the other vertebrates the epicardium of the quail embryo develops from proepicardial tissue located between the sinus horns and the liver primordium. The cuboidal cells of the coelomic lining above the proepicardium are transformed into mesothelial cells which in cooperation with the underlying mesenchymal cells elaborate a large quantity of extracellular matrix, so producing the villous outgrowths of the proepicardium. The mesenchymal cells of this area are attached to each other with typical desmosomes and have anti-alpha cytokeratin-stained tonofilament bundles. These cells resemble keratinocytes and are designated as proepicardial matrix keratinocytes. The proepicardium proliferates first in the sulci of the U-shaped tubular heart, and within 2 days (between stages 15-25) establishes the visceral layer of the epicardium. The proliferating proepicardium consists of gland-like tubular strands, formed by the invaginations of the surface mesothelial cells, mesenchymal cells, fibroblasts, angioblasts, blood cells and capillaries. Because of its heterogeneous structure and multiple functions, the proepicardium is considered a transitory organ of the developing heart. In the quail embryo the forerunners of the coronary vessels grow from the perihepatic area into the proepicardial organ, and when the epicardial covering is completed, but before the coronary artery orifices open, these primordial vessels form a subepicardial and intramural vascular network in the ventricular myocardium. After the completion of the epicardial covering the proepicardium involutes and is not seem from stage 26 onward.

Animals↗
PubMed1993

Immunohistochemical delineation of the conduction system. I: The sinoatrial node.

We have raised a mouse monoclonal antibody that reacts specifically with the myocytes of the sinoatrial node of the bovine heart. By use of this antibody (445-6E10) and antibodies against the gap junction protein connexin43, the periphery of the sinoatrial node and the distribution of gap junctions in the nodal region were studied. The reaction patterns of 445-6E10 and anti-connexin43 are exactly complementary; ie, connexin43 was not detected in the nodal myocytes but was clearly present in the atrial myocytes. Both reaction patterns demonstrate that nodal myocytes and atrial myocytes can unambiguously be distinguished by their characteristic molecular phenotype. The transitional nodal myocytes at the periphery of the node that have intermediate morphological and electrophysiological characteristics could now clearly be defined as nodal by our immunohistochemical criteria. The center of the node is surrounded by a region of interdigitating nodal and atrial bundles. Nodal bundles, coming from the center of the node, penetrate the atrial myocardium aligned at atrial bundles, forming histological connections between nodal and atrial myocytes at regular distances. This interdigitating arrangement of bundles of connexin43-negative nodal and connexin43-positive atrial myocytes is also found in the human and rat heart. We hypothesize that the architecture of the periphery of the node is important to prevent silencing of the pacemaking nodal myocytes by the atrium while ensuring a sufficient source loading of the nodal myocytes.

Adult↗
PubMed1993

Immunohistochemical delineation of the conduction system. II: The atrioventricular node and Purkinje fibers.

Using an antibody that reacts specifically with the myocytes of the conduction system of the bovine heart, we have studied the atrioventricular node and the spatial distribution of the Purkinje fibers in the bovine heart. This study was complemented by studying the distribution of the gap junction protein connexin43 in these areas in the bovine heart and in the human heart. The large Purkinje fibers in the bovine heart are arranged in a two-dimensional network underneath the endocardium. At discrete sites, these fibers branch to the Purkinje fibers situated between the muscle bundles of the ventricular mass. These intramural Purkinje fibers are arranged in sheets that form a complex three-dimensional network of lamellas. Contacts with the ventricular myocytes are found throughout the myocardial wall, with the exception of a subepicardial layer of 2-mm thickness, ie, 10% to 15% of the wall thickness. The spatial arrangement of the Purkinje fibers correlates well with data on electrophysiology. Connexin43 was not detected in the myocytes of the atrioventricular node, whereas in the Purkinje fibers of the atrioventricular bundle and of the bundle branches, abundant expression of connexin43 was found in both humans and cows. In the bovine Purkinje fibers, a remarkable subcellular distribution of connexin43 is found: it occupies the entire plasma membrane facing other Purkinje cells but not that facing the surrounding connective tissue. The structural differences in architecture of the ventricular conduction system in humans and cows seems not to result in substantial differences in conduction velocities. However, the Purkinje fiber network in the bovine heart may explain the efficient ventricular excitation, as reflected by the relatively short QRS complex compared with that in the human heart, where intramural Purkinje fibers are not found.

Adult↗
PubMed1992

Spatial distribution of "tissue-specific" antigens in the developing human heart and skeletal muscle. III. An immunohistochemical analysis of the distribution of the neural tissue antigen G1N2 in the embryonic heart; implications for the development of the atrioventricular conduction system.

A monoclonal antibody raised against an extract from the Ganglion Nodosum of the chick and designated G1N2 proves to bind specifically to a subpopulation of cardiomyocytes in the embryonic human heart. In the youngest stage examined (Carnegie stage 14, i.e., 4 1/2 weeks of development) these G1N2-expressing cells are localized in the myocardium that surrounds the foramen between the embryonic left and right ventricle. In the lesser curvature of the cardiac loop this "primary" ring occupies the lower part of the wall of the atrioventricular canal. During subsequent development, G1N2-expressing cells continue to identify the entrance to the right ventricle, but the shape of the ring changes as a result of the tissue remodelling that underlies cardiac septation. During the initial phases of this process the staining remains recognizable as a continuous band of cells in the myocardium that surrounds the developing right portion of the atrioventricular canal, subendocardially in the developing interventricular septum and around the junction of the embryonic left ventricle with the subaortic portion of the outflow tract. During the later stages of cardiac septation, the latter part of the ring discontinues to express G1N2, while upon the completion of septation, no G1N2-expressing cardiomyocytes can be detected anymore. The topographic distribution pattern of G1N suggests that the definitive ventricular conduction system derives from a ring of cells that initially surrounds the "primary" interventricular foramen. The results indicate that the atrioventricular bundle and bundle branches develop from G1N2-expressing myocytes in the interventricular septum, while the "compact" atrioventricular node develops at the junction of the band of G1N2-positive cells in the right atrioventricular junction (the right atrioventricular ring bundle) and the ("penetrating") atrioventricular bundle. A "dead-end tract" represents remnants of conductive tissue in the anterior part of the top of the interventricular septum. The location of the various components of the avian conduction system is topographically homologous with that of the G1N2-ring in the human embryonic heart, indicating a phylogenetically conserved origin of the conduction system in vertebrates.

Antigens↗
PubMed1992

New findings concerning ventricular septation in the human heart. Implications for maldevelopment.

BACKGROUND: The mechanics involved in development of the inlet component of the morphologically right ventricle are, as yet, undecided. Some argue that this component is derived from the descending limb of the ventricular loop, and that the inlet and apical trabecular components of the muscular ventricular septum have separate developmental origins. Others state that the entirety of the right ventricle grows from the ascending limb of the loop, and that the muscular septum, apart from its outer component, has a unitary origin. We now have material from human embryos at our disposal, which, we believe, solves this conundrum. METHODS AND RESULTS: We used a monoclonal antibody against an antigen to neural tissue from the chick to demarcate a ring of cells separating the descending (inlet) and ascending (outlet) limbs of the developing ventricular loop of the human heart. Preparation of serial sections of graded human embryos enabled us to trace the fate of this ring, and hence the formation of the inlet of the right ventricle, to the completion of cardiac septation. Eight embryos were studied, encompassing stages 14-23 of the Carnegie classification. The ring of cells initially separating the ascending and descending limbs of the ventricular loop were, at the conclusion of ventricular septation, located within the atrioventricular junction, sequestrated for the most part in the terminal segment of atrial myocardium. CONCLUSIONS: Our study conclusively shows that the inlet component of the morphologically right ventricle is derived from the ascending limb of the embryonic ventricular loop, and that the inlet and apical trabecular components of the muscular septum are derived from the same primary ventricular septum.

Antibodies, Monoclonal↗
PubMed1991

Spatial distribution of "tissue-specific" antigens in the developing human heart and skeletal muscle. II. An immunohistochemical analysis of myosin heavy chain isoform expression patterns in the embryonic heart.

The spatial distribution of alpha- and beta-myosin heavy chain isoforms (MHCs) was investigated immunohistochemically in the embryonic human heart between the 4th and the 8th week of development. The development of the overall MHC isoform expression pattern can be outlined as follows: (1) In all stages examined, beta-MHC is the predominant isoform in the ventricles and outflow tract (OFT), while alpha-MHC is the main isoform in the atria. In addition, alpha-MHC is also expressed in the ventricles at stage 14 and in the OFT from stage 14 to stage 19. This expression pattern is very reminiscent of that found in chicken and rat. (2) In the early embryonic stages the entire atrioventricular canal (AVC) wall expresses alpha-MHC whereas only the lower part expresses beta-MHC. The separation of atria and ventricles by the fibrous annulus takes place at the ventricular margin of the AVC wall. Hence, the beta-MHC expressing part of the AVC wall, including the right atrioventricular ring bundle, is eventually incorporated in the atria. (3) In the late embryonic stages (approx. 8 weeks of development) areas of alpha-MHC reappear in the ventricular myocardium, in particular in the subendocardial region at the top of the interventricular septum. These coexpressing cells are topographically related to the developing ventricular conduction system. (4) In the sinoatrial junction of all hearts examined alpha- and beta-MHC coexpressing cells are observed. In the older stages these cells are characteristically localized at the periphery of the SA node.

Adult↗
PubMed1990

Spatial distribution of "tissue-specific" antigens in the developing human heart and skeletal muscle. I. An immunohistochemical analysis of creatine kinase isoenzyme expression patterns.

Using monoclonal antibodies against the M and B subunit isoforms of creatine kinase (CK) we have investigated their distribution in developing human skeletal and cardiac muscle immunohistochemically. It is demonstrated that in skeletal muscle, a switch from CK-B to CK-M takes place around the week 8 of development, whereas in the developing heart, CK-M is the predominant isoform from the earliest stage examined onward (i.e., 4 1/2 weeks of development). In all hearts examined, local differences in concentration of the CK isoforms are observed. The CK-M expression in the developing outflow tract (OFT) and conduction system is described in detail. Between the weeks 5 and 7 of development, the distal portion of the OFT is characterized by low CK-M expression, whereas around the week 8-10 of development the myocardium around the developing semilunar valves in the OFT expresses a very high level of CK-M. At all stages examined, a relatively low CK-M level is observed in those regions in which the "slow" components of the conduction system do develop (e.g., the sinoatrial junction and atrioventricular junction), whereas a relatively high concentration of CK-M is observed in those areas that are destined to become the "fast" components, i.e., the subendocardial myocardium of the ventricles. The high expression of CK-M in the developing "fast components" of the conduction system contrasts with the relatively low expression of CK-M in the force-producing myocardium of the interventricular septum and free ventricular wall.

Creatine Kinase↗
PubMed1990

[Unity of diagnostic pathology, continuing education and research at our institute].

Authors give a brief view on the activity in Institute of Pathology and Histopathology of Post-graduate University of Medicine. In its frame, close relation of diagnostic, post-graduate education and research activity is illustrated by examples of different fields (intestinal, cardiac, vascular system, respiratory tract, organ of locomotion, urological diseases, electronmicroscopic tumor diagnostics, endocrinology). Importance of modern morphological methods and their place both in practical and scientific activity are dealt with.

Cardiovascular Diseases↗
PubMed1989

Formation of the primitive myo- and endocardial tubes in the chicken embryo.

The morphogenesis of the mesenchymal cardiogenic plate, the formation of the bilateral heart primordia leading to the primitive heart tube, and also the genesis of the endocardial tube, have been studied in 1 to 13 somite chick embryos. The morphological data were compared with those obtained in electrophysiological studies of the development of the cardiac action potentials (Fujii et al., 1981a). The primordia of the consecutive heart chambers are definable before the appearance of myosin-type filaments and primitive Z bands, which occurs simultaneously with the first spontaneous action potentials in the 7 somite embryo. At the 8 to 9 somite stage, fusion of the lateral heart primordia proceeds to include the outflow tract and atrial primordia; the pacemaker site migrates into the atrial wall and subsequently into the sinus venosus, this process occurring simultaneously with the progressive transformation of mesenchymal cells into cardiomyocytes. Proendocardial cells are first detected detaching individually or in small groups from the cardiogenic plate to become attached by fine filamentous material to the basal surface of the foregut endoderm, on which they "stream", establishing an anastomosing V-shaped array with respect to the ventral mesoderm. This array coalesces first at the atrioventricular groove to form double endocardial tubes, which in turn fuse into a single tube with the establishment of the single myocardial tube. Evidence suggests a key role for the ventral mesocardium and its transient attachment zone with the foregut, in providing a line focus for migration of proendocardial cells and primitive capillaries from the lateral splanchnic mesoderm, from which they derive.

Animals↗