Biomedical subjects

B Bednár

Publications and source records attributed to B Bednár.

At least 19 recordsLinked to original sources

PubMed2000

Expression of beta-catenins and cadherins by follicular dendritic cells in human lymph nodes.

In lymph nodes, dendritic cells form a complex meshwork and are linked by intercellular junctions. Intercellular junctions contribute to the integrity of lymphatic follicles and can potentially be affected by malignant processes in neighbouring B cells. We examined whether transmembrane molecules that constitute "adherens junctions" are present in follicular dendritic cells of normal human lymph nodes. We found that follicular dendritic cells but not interdigitating dendritic cells or sinus lining cells expressed cadherin molecules. Follicular dendritic cells also expressed beta-catenin but not vinculin. The cadherin molecules, which were identified in situ with the use of a monoclonal pan-cadherin antibody, were not recognized by antibodies to E-cadherin, N-cadherin or P-cadherin. Intrafollicularly, cadherins were clearly colocalized with beta-catenins, in a dot-like fashion. We also detected intrafollicular expression of desmogleins and desmosomal plaque proteins. These findings indicate the presence of desmosomes within the dendritic meshwork. However, pan-cadherin reactivity was not only colocalized with desmoglein immunoreactivity that was abundantly present. Immunoprecipitation showed that pan-cadherin reactivity was absent in fractions of desmosomal plaque proteins or pan-desmogleins. We speculate that complexes of cadherins of an unknown subclass and beta-catenins form non-desmosomal intercellular junctions in the intrafollicular dendritic meshwork.

Cadherins↗

PubMed1998

[Over a half-century at the Medical School of Charles University: 1. Student years].

Nearly all student years in Prague Medical School represented a "big class" schooling. Professors and their lectures were in the centre of programme and practical training was very limited. Interruption of studies during the war brought many difficulties but was in a way positive for those who had opportunity to further practical education. We found out that even a very good preparation by the medical school did not do and had to be complemented by the school of practice. Its standardization could be hardly achieved without any connection with a university department.

Czech Republic↗

PubMed1998

[Over a half-century at the Charles University 1st Medical Faculty. 2. Pathology under Professor Sikl].

Hlava Institute of Pathology was directed in a pleasant climate of broadminded indulgence. Sikl was easy to get in favour being personally attractive and imposing in work. He always sided with the youth and helped us even against authorities which made him more often laugh critically than treat with respect. Hlava Institute under Sikl became a model of progressing narrow specialization and modernizing. Sikl filled it with a programme of perspective development. Thus he prepared the whole discipline for cooperation which was useful for comparison of all findings with clinical picture. He made the biopsy independent and carried out its wide appreciation. He insisted upon the usage of big scale surveying histological cuts which he investigated thoroughly in detail. He did not live to see an explosion of methodological possibilities. Nevertheless, he prepared the structural diagnostics for an effective cooperation of all specialized methods.

Czechoslovakia↗

PubMed1998

[Over a half century at the 1st Medical School of Charles University: development of interdisciplinary cooperation].

A vast interdisciplinary and methodological cooperation became a leading feature of pathology. It brought critical evaluation and synthesis of data from several points of view without prevalence of a pure structural empirism. Nevertheless, detailed structural analysis remains an unmatched and effective introductory way of diagnostic algorithms. A wide methodology is not always useful in its capacity but should be open to each of teachers. For the time being we rely more on outstanding personalities. Call for them as well as their reasonable uniting may restore the original sense to the School Scientific Council.

Czech Republic↗

PubMed1996

[Diagnostic certainty of lymph node biopsy in malignancies].

Bioptic diagnosis of malignant processes in lymph nodes is a difficult method and is less accurate than sometimes expected. After transfer of haematological patients-as a rule to provide specialized treatment-a diagnostic baseline examination of biopsy is useful. The clinician procures for this "second reading" all basic data to improve the diagnostic certainty and deserves support. A controversial character of the assembled data is not associated with any specially or professional skill. It ensues, however, from the general principle of good care of the patient. In oncology a "second reading" is not a novelty. It is a recommended approach during typing according to the international classification of oncological diseases. Assessment of certainty (C factor) is moreover included in assessment of the grade of malignity in the TNM system.

Biopsy↗

PubMed1996

[Typing of malignant mantle zone lymphomas].

Principles derived from a group of 46 ML of the mantle zone are presented: Mantle pattern of a ML and its cytological structure are mostly sufficient for positive basic diagnosis. Diffuse mantle zone ML need detection of BCL-1 and CD5 hyperexpression which are characteristic for small-cell and centrocytoid forms when compared with BCL-2 positive centrofollicular lymphomas. B monocytoid lymphomas from the parafollicular subgroup as well as plasmacytoid ML from the marginal subgroup retain faint BCL-1 positivity but lose CD5 positivity. That may results in attempt of problematic narrowing of mantle zone definition because of existence of the mixed cellularity forms of mantle zone ML. Nodular mantle zone ML are clinically recognized late and are unsensitive to treatment which is opposite to the original idea of their relative benignity. M-coding of mantle zone ML is very defective because the codes do not separate nodular (perifollicular) and diffuse variants.

Humans↗

PubMed1996

[PCR analysis of DNA in paraffin sections of malignant lymphomas].

The polymerase chain reaction was used to detect the clonal rearrangement of immunoglobulin heavy chain gene in paraffin embedded samples of human lymph nodes. We developed a sensitive and reliable method of the DNA isolation from 4-5 tissue sections, which enabled us to perform 50-100 PCR reactions. We compared the reactive lymph nodes and non-Hodgkin's malignant lymphomas using framework 3 and J region primers. PCR products were examined by agarose gel electrophoresis. The dominant 80-120 bp amplification product was found in all lymphoma samples. The samples of reactive nodes were negative.

DNA, Neoplasm↗

PubMed1996

[Visceral and cutaneous leishmaniasis].

Two cases of kala azar and 5 cases of cutaneous leishmaniasis were found in bioptic files from previous 50 years in Hlava Institute of Pathology in Prague, 4 of them were cumulated in 1994 and 1995. All cases followed short stays in Mediterranean or Caribbean area. The latest kala azar was identified from bone marrow trephine biopsy and subsequently, leishmanias were also found in an inapparent hepatopathy. In cutaneous cases, a fibrinoid vasculitis was observed in addition to accumulation of leishmanias laden macrophages and tuberculoid granulomas.

Humans↗

PubMed1995

[Dendritic resident cells and their immunohistologic determination].

Resident dendritic cells exist in various tissues. They belong to RES according to determining marks and their transitions. The main marks represent phagocytosis, fixed and mobile scavenging, endothelial and stroma-parenchyma barrier function and collagens production. Suppression of some extreme marks stimulates prevalence of remaining marks. An interesting topic concerns immune engaged dendritic cells. Their main mark is inability of transporting antigens and of presenting them to lymphatic tissue so that they start an immune reaction. Differences among dendritic cells can be detected by immunohistology. Immunopositivity of resident dendritic cells was studied in 20 tissues (lymphatic, skin, bone, soft, nervous, myocardial, lung, oesophagus, stomach, intestinal and others) by using antibodies: CD 34, F XIIIa, F VIII, actin, CD 68, S-100 protein, HLA-DR, CD3, and OPD4. Because a simple comparison of detected immunophenotypes was often ambiguous, positivity of dendritic cells was compared with positivity level of neighbouring tissues in 16 cases. Nevertheless, any single marker was not relevant in all cases. But decisive positive combinations did exist (CD 34 for non-X cells, CD 68 for phagocytes, S-100 for X cells). Dendritic cells in different and often opposite relations were found in a group of 36 cases. Diversity of tissue representation of "immunosupervising" dendritic cells reflected probably a frequence and quality of antigen stimulation in locally specific immune conditions. A surprising presence of CD 34 positive dendritic cells in border-line and stromal structures of nerves and in their tumours contributed to differential diagnosis of neurofibromas and some storiform tumours. CD 34 positivity alone does not solve problems sufficiently and applied methods will not do for determination of the share of "immunosupervising" cells in stromal reaction of malignant tumours.

Antigens, CD↗

PubMed1995

[The second reading of hematologic biopsies].

Occurrence of differences between the first and the second reading was compared in three time periods. The first from the years 1975-1989 showed disagreement in 34%, the second from 1990-1991 in 86%, the latest from 1994-1995 in 45%. The failures of the same sort repeated in 19 from 42 cases. They could be avoided by confining capacities of one's own department and using advantage of consulting reading by other pathologist. The second reading asked by an oncologist represents an independent urgent part of individual patient's treatment and should be generally supported and freed from any hindrance.

Biopsy↗

PubMed1995

[Comments on the suggested new classification of malignant lymphomas].

New classification of malignant lymphomas is based on a problematic intention of weakening the basic importance of topography for their precise evaluation. It is quite asymmetrical in establishing leading units. To omit existing coding possibilities of the malignant lymphomas is disappointing.

Humans↗

PubMed1994

[Trephine biopsy of the bone marrow in hematologic tumors].

A group of 1000 random trephine biopsies were evaluated according to their usefulness for typing and staging of haematological tumours. Trephine biopsy contributed someway to clinical data in half the cases. Primary medullary processes showed an excellent correspondence of clinical and bioptical data. Biopsy contributed substantially to specification of myeloproliferations and myodysplasias. There were only 24% of negative results (descriptive inconclusive). Malignant lymphomas presented situation analogical to leucaemias. Peripherical malignant lymphomas in medulla mostly did not follow diversity of lymph node phenomena and did not contribute to more detailed typing but enabled satisfactory staging. Malignant lymphomas were located, unlike leucaemia, intertrabeculary or peritrabeculary and often induced reactive myeloproliferation or scarring. Biopsy was usually good for separation of medullary carcinosis. Remarks to technology of getting and processing of bioptical sample were discussed.

Biopsy↗

PubMed1994

[Ring-cell immunocytoma with polyneuropathy associated with dysgammaglobulinemia and amyloidosis].

Dysgammaglobulinemia, amyloidosis and generalization of tumour occurred step by step in sensomotoric polyneuropathy complicating a nonspecified malignant lymphoma. The tumor was specified later as a IgM lambda immunocytoma with substantial participation of signet ring cells. Their vacuoles were sometimes multivesicular and did not contain immunoglobulins. Final phase of the disease was characterized by nodular AL amyloidosis expressed especially in the lung, retroperitoneum and nervous system. Amyloidosis was connected with the vessel walls and their surroundings. Possible autoimmune pathogenesis of polyneuropathy as well as of immunocyte vacuolization were discussed.

Adult↗

PubMed1993

[The certainty of biopsies in the diagnosis of tumors].

Wrong or incorrect tumour biopsy diagnosis is often found out by second reading before starting treatment. But overlooked malignancies can escape as well as malignant tumour mistaken for another causing biased treatment with complications. A collection of 59 bioptic mistakes showed not only dispersion but repetition of some of them in nosologic groups. A detailed attention was paid to them and their prevention was recommended. A claim to reproducibility of conclusions represents a withdrawal from presumed clearly empiric nature of bioptic diagnosis.

Biopsy↗

PubMed1993

[The mantle zone in lymphatic follicles and its stratification].

Ten inguinal lymph nodes and spleens from autopsies were chosen according to age decades in order to get an idea about usual appearance of follicular structures. The group was complemented by 4 palatine tonsils from routine biopsies. Phenotype was ascertained by using about 30 standard markers and results were compared with a basic histocytological picture. The appearance of lymphatic tissue was quite different according to location and age categories, nevertheless, there were common immunophenotypic and structural features of follicular mantle in younger persons. It mostly comprised four cellular layers, more conspicuous at the upper pole of the follicle. An innermost layer was small-celled blastic, MB 2 and IgD positive, the next B monocytoid layer had medium sized cells of a similar phenotype but more alc, phosphatase positive. An inconstant plasmacytoid layer and a clarocellular layer used to be incomplete. It was cytostructurally characteristic but immunohistologically non-standard (faint CD 19 et CD 20 positivity). T 4 lymphocytes and perhaps some other elements leaving germinal centres were admixed into the inner mantle layer. Various small lymphoid cells, especially T 8 lymphocytes and sometimes litoral cells, were admixed into mantle periphery. Mutual exchange of lymphatic cells between the germinal and mantle zones was very scant. The mantle zone is presumed therefore to be independent from the structural and functional point of view as well.

Adolescent↗

PubMed1993

[Cytostructure of the mantle zone in lymphatic tissue].

Four cellular layers of the follicular mantle zone in palatine tonsil lymphatic tissue were studied by electron microscopy after simultaneous immunophenotypical investigation. The first layer of the mantle zone consisting of small blastic cells was analogous to the small (centrocytoid) blastic layer of germinal centres. The second B monocytoid layer was lacking analogy in basic series of lymphocytes and seemed to be an independent morphological and probably functional unit. Plasmacytoid and clarocellular elements in outer layers of follicular mantle zone were in a way similar to T plasmacytoid and clarocellular components of Sézary syndrome infiltrates but considering transitional forms they had a local origin from incompletely transformed elements of B monocytoid layer. Inner follicular mantle zone was discussed as a source of incompletely transformed B lymphocytes for further mantle layers where their immunophenotypical modulation is taking place according to actual need. Outer mantle layers are aggressive against damaged epithelial and litoral structures and may be instrumental in a common reaction of B and T components.

Humans↗

PubMed1993

[Inclusions of cytoplasmic fibrillar degradation and ubiquitin].

Cell degradation of various origin often starts with an ubiquitinization of damaged proteins and with later production of roughly fibrillar electron-microscopical inclusions. There is a strong immunohistological positivity of ubiquitin in the early intracellular phase. It tends toward an apoptotic lysis either ending with extracellular immunohistologically inert refuse of amyloid type or representing various inter-steps of the degradation process. The ubiquitinization is the most common in neurons and paraneurons. A general importance of ubiquitinization is proved by ubiquitin fibrillar inclusions which were observed in growing old tissue cultures as an expression of programmed cell death. Immunodetection of increased ubiquitin is labour-saving as compared with some classical methods detecting similar lesions particularly in neuropathology.

Cell Line↗

PubMed1992

[Theory of multistep lymphocyte transformation].

The transformation of B lymphocytes in lymph nodes proceeds from the specialized small (centrocytoid) blast cell of the lymphatic tissue germinal centre base. It runs three subsequent steps. The transformation stream of lymphocytes of the first step is derived from the basal matrix of germinal centres and is aimed towards its replica in the mantle zone. Therein the transformed cells are supplemented and qualitatively altered towards the prevailing monocytic cells of the second step. The monocytoid cells are squeezed through the mantle zone under the basal part of the germinal centres. The third step continues in the terminal medullary direction, functionally linking up to the T4 paracortical nodules. A hierarchic feedback mechanism operates between individual steps, but partial hyperplasia of one step is possible. Under adequate antigenic stimulation, effector cells of local significance are derived from the main stream of incompletely transformed cells. During the first step (germinal centres) it is the lymphoplasmacytoid cells, whereas immunocytes and autoaggressive clear cells are produced during the second (mantle zone) step. The third (medullary) step as the final one results in the development of committed blood lymphocytes and plasmacytes. Transformation depends on local structural conditions, but immediate generic relations are not always present. The theory may be useful for the understanding of hyperplastic and neoplastic conditions usually comprising mixtures of cells belonging to one transformation step.

Humans↗