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Biomedical subjects

L Richter

Publications and source records attributed to L Richter.

At least 73 records · Page 4Linked to original sources
PubMed1987

Delineation of a novel pre-B cell component in plasma cell myeloma: immunochemical, immunophenotypic, genotypic, cytologic, cell culture, and kinetic features.

A novel pre-B cell component in direct and cultured myeloma bone marrow material has been delineated by using immunochemistry and flow cytometry techniques. Our phenotypic studies suggest a novel hybrid expression of pre-B and plasma cell antigens with coexpression of cytoplasmic mu, common acute lymphoblastic leukemia antigen, terminal deoxynucleotidyl transferase, and plasma cell antigens (PCA-1 and PC-1). This suggests that myeloma pre-B-like cells are aberrant malignant cells and not normal pre-B lymphocytic counterparts. With the advantage of a pure and stable source of these cells from M3 culture to allow molecular characterization, we performed one- and two-dimensional gel electrophoresis and Western blotting. We found that the cytoplasmic mu in myeloma pre-B-like cells has a molecular weight of 74,000 daltons and an isoelectric point of 6.3 and that it is strikingly homogeneous and discrete in size and charge compared with standard secretory mu, which suggests an aberrant, mutant, or monoclonal form of mu. Monoclonality was further evidenced by heavy- and light-chain immunoglobulin gene rearrangements demonstrated with JH and C kappa probes. We also established that this novel myeloma pre-B component is a major proliferative element as determined by double-labeling experiments with phenotype coupled to labeling/proliferative indexes. Our stimulatory studies indicate some capacity of these cells to mature on exposure to phorbol esters. These myeloma pre-B cells may represent the stem cell or self-renewal component in myeloma. Our establishment of these cells in long-term culture offers a considerable asset in studying the immature cells, which may be critical to the immortalization of myeloma.

B-Lymphocytes↗
PubMed1987

Cutaneous myiasis. Immunohistologic and ultrastructural morphometric features of a human botfly lesion.

This study documents the immunohistologic and ultrastructural morphometric features of a case of cutaneous myiasis due to Dermatobia hominis. The mixed host inflammatory response surrounding the larvae included lymphoblasts, eosinophils, activated fibroblasts, mature histiocytes, mast cells, plasma cells, and Langerhans cells, indicating a complex interactive immunologic response to the botfly parasite. Immunotyping revealed that the dominant dermal cells were activated (Ia+) T-helper cells. Although the strikingly elevated T-helper/T-suppressor cell ratio might suggest a monoclonal infiltrate, a mixture of Leu 8+ and Leu 8- T-cells indicates both immunoregulatory subsets of T-helper cells as found in a reactive process. Furthermore, our ultrastructural histogram found the lymphoid nuclear shapes were oval with few nuclear invaginations as found in inflammatory infiltrates. As indicated by electron microscopy, there were abundant activated fibroblasts elaborating collagen which may relate to larval containment.

Central America↗
PubMed1986

Immunophenotypes in "well-differentiated" lymphoproliferative disorders, with emphasis on small lymphocytic lymphoma.

The histologic, immunophenotypic, and clinical findings in 24 cases of "well-differentiated" lymphoproliferative disorders are presented, with an emphasis on small lymphocytic lymphoma (SLL; well-differentiated lymphocytic lymphoma, WDLL). SLL was diagnosed in 18 patients, Waldenström's macroglobulinemia in one, mantle zone lymphoma (MZL) in four, and intermediate differentiated lymphocytic lymphoma (IDL) in one. Immunophenotypic analysis revealed one SLL to be of T-cell derivation, while a monoclonal B-cell phenotype was found in the remaining 23 patients; 20 of these neoplasms co-expressed the pan-T-cell antigen Leu-1. This included three of the four patients with MZL and the patient with IDL. All SLLs with pseudofollicular growth centers stained for transferrin receptor. Additionally, a survey of 248 non-Hodgkin's lymphomas of all types revealed four of 70 patients with B-cell large cell lymphoma (LCL; diffuse histiocytic lymphoma, DHL) that also co-expressed the same Leu-1 antigen. Immunoperoxidase study of both frozen tissue sections and cytocentrifuge preparations eliminated the limitations of faint antigen expression and/or interstitial immunoglobulin staining. In addition to detailing the immunophenotype of SLL, the immunologic kinship of MZL/IDL to SLL and the uncommon co-expression of Leu-1 in B-cell LCLs are demonstrated.

Aged↗
PubMed1986

Immunologic complexity of lymphoblastic lymphoma.

Twelve patients with a histologic diagnosis of lymphoblastic lymphoma (LBL) were studied immunologically using the methodologic refinement of comparative serial section immunochemistry. By this means, we demonstrate complex LBL phenotypic profiles, revealing 3 major immunologic subtypes: immature T cell, 7 cases; intermediate or mature T cell, 3 cases; immature B cell (pre-pre-B), 2 cases. This phenotypic diversity challenges the basic belief that all LBL are the same. Our immature T-cell cases with frequent simultaneous Leu 2/3/6/9/CALLA/Tdt expression correspond to cortical thymic phenotypes; our mature T-cell phenotypes with Leu 9/la expression and absent L6/Tdt correspond either to medullary thymocytes or post-thymic T cells; our pre-pre-B phenotypes with simultaneous Tdt/CALLA/B4 expression correspond to common acute lymphocytic leukemia (ALL) phenotypes. Mature T-LBL phenotypes are similar to "novel" peripheral T-cell lymphoma phenotypes. Scant or absent Tdt expression in mature LBL is not an isolated antigenic change but a complete phenotypic profile difference from immature T-LBL. The major T- and B-cell phenotypes of LBL might have therapeutic significance. Treatment among LBL phenotypes may need to vary as with acute lymphocytic leukemia phenotypes. Further study is needed; in the meantime, comparative serial section immunotyping promises substantial utility in revealing the immunologic complexity of the lymphomas.

Adolescent↗
PubMed1986

Immunoarchitecture of the regenerating rat spleen: effects of partial splenectomy and heterotopic autotransplantation.

To investigate the microstructure of in situ (eutopic) and autotransplanted (ectopic) splenic remnants, adult Sprague-Dawley rats were studied 60 days after subtotal (approximately 80%) splenectomy, total splenectomy followed by single or multiple remnant intraperitoneal autotransplantation, or sham operation. Total nucleated cell counts were determined in excised splenic remnants, and immunohistochemical staining using monoclonal antibodies to rat B- and T-cell antigens was performed in serial tissue sections. Immunoarchitecture of eutopic remnants was indistinguishable from that of intact spleens and total nucleated cell counts remained proportional to weight. In contrast, ectopic remnants showed sparsity and abnormal mixing of B and T lymphocyte subpopulations with widespread loss of follicles and periarteriolar lymphoid sheaths in addition to lower density and marked reduction of total nucleated cells. These findings provide immunohistologic evidence that preservation of intact vasculature is critical to splenic architecture, which may account in part for the demonstrable functional inferiority of ectopic remnants.

Animals↗
PubMed1985

Immunotopographic assessment of lymphoid and plasma cell malignancies in the bone marrow.

To determine the utility of tissue section immunochemistry in the evaluation of bone marrow involved by lymphoid and plasma cell malignancies, snap-frozen, undecalcified bone marrow core and aspirate samples from 23 patients with these disorders were studied with a battery of monoclonal antibodies. With techniques that preserve architecture, difficult diagnostic cases characterized by core but not aspirate involvement, or the reverse, were resolved. By means of an extensive battery of monoclonal antibodies applied to serial sections, complex tumor cell phenotypes were established in all 23 cases. In addition to the identification of straightforward monoclonal surface immunoglobulin expression in small cleaved cell lymphomas (four cases), the battery approach added immunologic certainty in malignancies with unusual or difficult phenotypes: peripheral T-cell lymphomas with idiosyncratic antigen expression, and chronic lymphocytic leukemias and small cell lymphomas with faint surface immunoglobulin expression (four cases). For the chronic lymphocytic leukemias and the small cell lymphomas, the combined IgD+, B2+, B1+, Ia+, Leu-1+ phenotype taken as a whole had greater utility than any isolated marker. The acute lymphocytic leukemias and the myelomas studied demonstrate the wide range of B-cell antigens that must be detected to account for the variety of B-cell neoplasms encountered. Additionally, the previously undescribed phenotypic subset of CALLA+ myelomas, which is of prognostic relevance, was identified. Marrow frozen section immunotyping is a major asset in the evaluation of patients with lymphoma, leukemia, and myeloma when special care is accorded to tissue handling and to treatment of endogenous peroxidase/pseudoperoxidase and interstitial immunoglobulin.

Antibodies, Monoclonal↗
PubMed1984

Conserved 5' flank homologies in dipteran 5S RNA genes that would function on 'A' form DNA.

We have sequenced the 480 base pair (bp) repeating unit of the 5S RNA genes of the Dipteran fly Calliphora erythrocephala and compared this sequence to the three known 5S RNA gene sequences from the Dipteran Genus Drosophila (1,2). A striking series of five perfectly conserved homologies identically positioned within the 5' flanks of all four Dipteran 5S RNA coding regions has thus been identified. The spacing (12-13 bp) between all of these homologies is typical of A form rather than B form DNA. Given that the eukaryotic 5S RNA gene specific initiation factor TFIIIA (3) is a DNA unwinding protein (4), a role for these Dipteran 5' flank homologies in initiation site selection on 5S RNA genes transiently unwound for transcription is suggested. One of the Dipteran homology blocks is highly conserved in sequence and position in all but one of the eukaryotic 5S RNA gene sequences known to date (17/18 genes). Its sequence (consensus: TATAAG) and position (average center: -26 bp) are highly reminiscent of the polymerase II gene 'TATA' box (5).

Animals↗
PubMed1984

Computergraphics in a full-service department: a three-year experience.

A three-year experience in computergraphics has proven to be cost-effective in a full-service, totally self-supporting biocommunications department. Workload has continued to increase in art and photography, and the departmental staff has increased by 1.5 full-time equivalents. A satellite computergraphics production unit with a staff of three illustrators has emerged as a viable service of the department.

Academic Medical Centers↗
PubMed1983

Electrokinetic properties of polymer and glass surfaces in aqueous solutions: experimental evidence for swollen surface layers.

Streaming potential and streaming current measuring techniques have been applied to polymer and glass surfaces to study solid/liquid interface electrical properties. The streaming current technique provides a reliable electrokinetic potential value, preexcluding surface conduction. A combination of both techniques results in experimental evidences for swollen, gel-like layers at (even apolar) polymer surfaces. Protons and hydroxide ions are the potential-determining ions indicated by the dependence of streaming potential on pH. Human serum albumin adsorption at a glass surface is discussed in terms of spatial distribution of the fixed macromolecular electric charges.

Adsorption↗
PubMed1979

Physician and patient acceptance of emergency nurse practitioners.

Patient and physician attitudes toward emergency nurse practitioners (ENP) were surveyed in our emergency medical service. The responses to the questionnaires indicated a high degree of satisfaction with the ENP similar to that reported in a survey of patient reaction to physician assistants (PA) in the emergency department. In our emergency medical service, physicians expressed a concern over the practitioner's care of the emergent patient. Their confidence in the practitioner's clinical judgment was greater in their care of nonurgent and urgent patients.

Attitude↗