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Biomedical subjects

L Richter

Publications and source records attributed to L Richter.

At least 19 recordsLinked to original sources
PubMed1992

[The development of the yolk sac in ruminants (sheep and cattle)].

Yolk sac development was investigated in 69 ovine and 10 bovine embryos from the blastocyst stage to the 7th week of gestation. Light and electron microscopical findings are reported. The yolk sac in sheep and cattle is composed of an enlarged sac-like portion lying below the embryo and two ends which follow the elongated course of the trophoblast. In sheep, an open connection exists between the intestines and the yolk sac up to a crown-rump length (CRL) of 9 mm. It is closed by 12 mm CRL. The wall of the yolk sac is especially well vascularized in the enlarged, sac-like portion. Primary erythropoiesis occurs within the blood capillaries. In the blastocyst, the yolk sac entoderm is made up of elongated, flat cells. It becomes cuboidal in the 3 mm embryo (ovine) and later columnar. The up to 20 microns tall cells stain darkly and contain numerous light-colored vesicles. At 4.5 mm CRL light cells appear between the dark ones. Both cells are rich in rough endoplasmic reticulum (rER). The increased staining of the darker cells is due to an osmophilic cytoplasm and numerous, often parallel lamella of rER. The rER of the light cells is enlarged to irregularly-shaped cisternae, which nearly fill the entire cytoplasm and give them a rounded appearance. The dark cells contain polygonal nuclei, whereas those in the light cells are round with one or two nucleoli. The oval mitochondria have only a few peripheral cristae. Golgi fields are not very common. Cells of the entoderm are connected to one another over zonulae occludentes. They possess microvilli on the luminal surface and are supported by a basement membrane. From 5 mm CRL onwards (ovine), the yolk sac entoderm folds itself between the capillaries, thereby becoming stratified. The intercellular space between the cells expands as projections between neighboring cells interlock. Canaliculi arise between adjacent epithelia. The wall of the yolk sac thickens as a result of this infolding and the densely packed capillaries. Infoldings are especially predominant in the sac-like portion of the yolk sac, and only suggested in the ends. Involution of the yolk sac begins in the peripheral end segments and proceeds centripetally. Numerous glycogen particles appear in the yolk sac entoderm cells of the ovine fetus at a CRL of 36 mm, and by a CRL of 42 mm, the sac-like portion has also begun to show signs of degeneration. Mesenchyme is very sparse within the wall of the yolk sac throughout the entire period of development.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Characterization of the memory gene dunce of Drosophila melanogaster.

The dunce (dnc) gene of Drosophila melanogaster encodes cAMP phosphodiesterase (PDEase) and is required for learning/memory and female fertility. The gene is structurally complex, demonstrated in part by Northern blotting experiments which detected multiple RNAs ranging in size from 4.2 to 9.6 kb (1 kb = 10(3) bases or base-pairs). To characterize these RNAs and to understand their sequence heterogeneity, we isolated and analyzed 29 new and independent cDNA clones representing the dnc RNAs. Restriction mapping, hybridization analysis and sequence determination of these cDNA clones and the corresponding genomic exons resolved these into six different classes. Exons defined by the cDNA clones are distributed over more than 148 kb of genomic DNA, with some exons being used alternatively among the RNAs. The RNAs are transcribed from at least three initiation sites: two of these were mapped by parallel S1-nuclease and primer extension experiments. In addition, some of the heterogeneity is generated by using varying lengths of a 3'-untranslated trailer sequence. Altogether, the results indicate that the size and sequence heterogeneity of dnc transcripts results from transcription initiation at multiple sites, alternative splicing, and processes which generate different 3' ends. The existence of multiple protein products is suggested by the alternative use of exons which code for portions of the open reading frame. The protein variation potentially includes N-terminal differences coded for by transcript-specific 5' exons and internal differences arising from the optional inclusion of a 39 base-pair exon and from the alternative use of two 3' splice sites separated by six base-pairs. Expression of a cDNA clone in yeast containing a large portion of the open reading frame produced cAMP PDEase activity identical in properties to the Drosophila enzyme affected by the dnc mutation. The results suggest that the remarkable structural complexity of dnc may reflect an intricate control of the spatial and/or temporal expression of various isoforms of cAMP PDEase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1991

Birth to ten: child health in South Africa in the 1990s. Rationale and methods of a birth cohort study.

Birth to Ten is a longitudinal birth cohort study which began in April 1990 in the Johannesburg/Soweto area of Transvaal, South Africa. In this paper, the reason for the initiation of the study and its location in the current sociopolitical context is discussed. The health status of South Africa children in terms of infant mortality, morbidity (notifiable diseases) and nutritional status is described and mention is made of measures of psychological health and the importance of environmental pollution on health. The existing health service infrastructure in the study area is described and the fragmentation of health services between races, between preventive and curative services and on a geographical basis is highlighted. The study objectives, design, population, inclusion and exclusion criteria, methods of measurement and logistics are described.

Child↗
PubMed1990

Plasma cells in multiple myeloma express a natural killer cell-associated antigen: CD56 (NKH-1; Leu-19).

Bone marrow samples from 55 patients with multiple myeloma (MM) and 23 patients with monoclonal gammopathy of undertermined significance (MGUS) were evaluated with a broad panel of monoclonal antibodies. Plasma cells from 78% (43/55) of patients with MM strongly expressed the natural killer cell antigen CD56 (NKH-1, Leu-19). Of the 23 patients with MGUS, none showed strong CD56 reactivity, although three had weak reactivity in less than 20% of plasma cells. Myeloma cells expressing CD56 did not coexpress the CD57 or CD16 antigens. Patients with CD56-positive plasma cells had both indolent and aggressive disease. However, the 12 CD56-negative patients had predominantly aggressive disease with an unexpected preponderance of kappa Bence Jones only myeloma (5/10[50%] evaluable patients). Polyclonal plasma cells from non-neoplastic tissue sites (normal bone marrows, lymph nodes, tonsillar biopsies, and gut-mucosa biopsies) showed a near absence of CD56. We conclude that isolated, strong CD56 expression is common in MM, but not in MGUS or reactive plasma cells. The potential biologic importance of CD56 positivity in myeloma is reviewed.

ADP-ribosyl Cyclase↗
PubMed1990

Ultrasonographic anatomy of normal prostate gland: reconstruction by computer graphics.

Computer graphic reconstructions of the prostate were made in both the transverse (axial) and longitudinal (sagittal) planes at different levels on the basis of the normal anatomic model of McNeal. Additional images then were created to give a picture of what the ultrasonogram should look like at each level, and these were compared with actual ultrasonograms of the normal prostate. A precise yet simple terminology is suggested for prostate ultrasonographic descriptions.

Adult↗
PubMed1990

Optimization of immunocytochemical P-glycoprotein assessment in multidrug-resistant plasma cell myeloma using three antibodies.

Seeking to optimize the immunocytochemical assay of P-glycoprotein, a 170-kilodalton (P-170) molecule associated with multidrug resistance, we experimented with a variety of antibodies (JSB-1, C219, and MRK-16), fixation conditions, and titers using both human myeloma cell lines and clinical myeloma specimens. Under optimized conditions, using all three antibodies and the cell lines as standards and controls, the ICC method proved sensitive, specific, reliable, rapid, and within the realm of everyday hospital laboratory expertise. The 3 anti-P-glycoprotein antibodies revealed different reactivities with P-170. Both C219 and JSB1 were optimized by fixation in cold acetone. With MRK-16 optimal results were obtained on unfixed or formalin fixed specimens. Under optimal fixation and titering conditions, low level (DOX 4) detection was possible. Given that the three antibodies differ in reactivity and recognize different P-170 epitopes, it follows that using the antibodies in a small panel is a useful strategy in increasing the likelihood of detecting true P-glycoprotein expression by the immunocytochemical method. In dilution experiments, the immunocytochemical method was as sensitive as RNase protection assay and more sensitive than Western blot detection. Immunocytochemistry coupled to computer-assisted single-cell densitometry, showed a strong correlation (R = 0.98) between cellular P-170 density and in vitro resistance to doxorubicin. Multidrug-resistant specific probes for RNA expression and Western blot assays confirmed the specificity of P-170 expression in both cell lines and clinical samples. Thus, a small panel of antibodies, under optimized immunocytochemical conditions, appears to have potential as a rapid, sensitive, clinically useful assay for multidrug resistance in myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

[The appearance of ovarian cysts in young sows after treatment with gonadotropin preparations for estrus induction].

In 72 (46%) of 155 gilts discarded for genetic reasons after performance testing and housed under fattening conditions no heat could have been detected during the first 30 days. The gilts were assigned alternatingly to a control group and four different treatments of delayed puberty. The induction of puberty was carried out by injections of 1000 iu PMSG, 400 iu HCG and 2 mg oestradiol benzoate, 400 iu PMSG and 200 iu HCG and 800 iu PMSG and 400 iu HCG. If there was no estrus gilts were slaughtered 12 days later for examination of the ovaries. Those coming into estrus were slaughtered 8 days after disappearance of estrus. Estrus could be induced in 69 to 94% of the gilts, whereas 40% of the untreated showed estrus signs. After treatment with PMSG and HCG in 40 and 87% of the gilts cysts were found whereas none of the untreated and 26 and 29% of those treated with PMSG und HCG + oestradiol benzoate revealed ovarian cysts. In addition, those gilts that had come into estrus during the first 30 days were given injections of either 1000 iu PMSG or 800 iu PMSG and 400 iu HCG. The injections were made either on the 5th, 10th or 15th day of cycle. In both latter groups significantly more gilts showed standing heat than after treatment at cycle day 5. The results of inspection of the ovaries at slaughter and steroid hormones could not be assigned to a defined stage of the physiological ovarian cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Immunohistochemical detection and quantitation of P-glycoprotein in multiple drug-resistant human myeloma cells: association with level of drug resistance and drug accumulation.

Using several multiple drug-resistant human myeloma cell lines as standards, we developed an immunohistochemical staining technique and means of quantitating P-glycoprotein in individual myeloma cells. The level of staining intensity for P-glycoprotein in individual myeloma cells was quantitated by measuring the average optical density of each cell with a microscopic computerized cell analysis system. Using this system, we observed that the level of P-glycoprotein for individual cells within a cell population of known drug sensitivity was very homogeneous (coefficient of variation less than or equal to 13%). Analysis of cell lines with gradually increasing levels of multidrug resistance (8226/S, 8226/Dox6 and 8226/Dox40) demonstrated a close association between the level of resistance to doxorubicin, defined by the mean lethal dose (D0) and the amount of P-glycoprotein on individual cells determined by the optical density (r = 0.82, P less than 0.0005). Intracellular doxorubicin (DOX) accumulation in the individual cell lines was inversely related to the level of drug resistance expressed as D0. P-glycoprotein was also detected in the marrow-derived myeloma cells of patients with drug refractory disease using immunohistochemical staining. The amount of P-glycoprotein in the cells of one patient was directly compared to the amount found in the simultaneously stained standard cell lines (8226/Dox6 and 8226/Dox40) by comparing the optical densities for individual cells. Using this immunohistochemical technique to detect and quantitate P-glycoprotein in patient myeloma cells and comparing it to standard multidrug resistant myeloma cell lines may be of value in determining the contribution of P-glycoprotein to clinical drug resistance in patients with multiple myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Myelomonocytic antigen positive multiple myeloma.

In a four year span, between 1983 and 1987, 215 bone marrow and cell culture samples from 125 myeloma patients were immunotyped and coexpression of myelomonocytic and plasma cell antigens occurred in 16 (13%). We employed both immunohistochemical and flow cytometry methods including coplots and double labelling. Three types of myeloma cases were found: (1) those with isolated myeloid antigen coexpression, usually Leu M1 or esterase (BE, CE) positive (11 cases); (2) those with multiple myeloid antigens (Leu M1, M3, M5, MY7, BE, CE) (four cases); and (3) one case beginning as 1 and ending as 2. Isolated myeloid antigen expression was generally associated with typical features of myeloma with survival close to the anticipated median (33 months), while multiple myeloid antigen expression was associated with more aggressive disease and shorter survival duration (median survival 16 months). The latter subgroup also had other poor prognostic factors including high labelling index and common acute lymphoblastic leukemia antigen (CALLA) positivity. Other features found overall were frequent abnormal karyotypes (seven of 12 abnormal) and coexpressed IgA (eight of 16); all IgA+ cases also coexpressed Leu M1. We conclude that there is an unusual and unexpected predilection for coexpression of myelomonocytic antigens in myeloma cells. The reasons are not immediately obvious. Whether the coexpression indicates that myeloma cells truly have latent multilineage potential or just aberrantly coexpress other hematopoietic antigens as a manifestation of malignancy remains to be explained. However, a cell line established from the bone marrow of one patient is a valuable scientific tool allowing detailed analysis of these questions.

Antigens, Differentiation, Myelomonocytic↗
PubMed1989

[Muscular burden in current work activities exemplified by cash register work sites].

21 cash register operators (aged 18 to 49 years) have been studied in an industrial study. The investigation included the measurement of heart rate, bioelectrical muscle activity of the right and left M. biceps brachii and M. deltoideus and muscular endurance at 50% MVC. There were significant relationships between the movement of the left arm and the heart rate and the load of articles and the heart rate. The results in bioelectrical activity showed that there were a muscular load in the right and left muscles and findings of muscular fatigue in frequency distribution and in muscular endurance.

Adolescent↗
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↗