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Biomedical subjects

R Mallinger

Publications and source records attributed to R Mallinger.

At least 37 records · Page 2Linked to original sources
PubMed1995

Biomechanical properties of normal tendons, normal palmar aponeuroses, and tissues from patients with Dupuytren's disease subjected to elastase and chondroitinase treatment.

Normal tendons, normal palmar aponeuroses and palmar aponeuroses from patients with Dupuytren's disease were subjected to elastase or chondroitinase treatment. Young's modulus was derived from the linear portion of stress-strain graph. It showed the lowest value for the apparently normal palmar aponeuroses and the highest value for tendon samples. Elastase treatment caused an increase of extensibility and a reduction of Young's modulus of normal palmar aponeuroses and tendons, but not of contracture bands. In normal tendons, normal palmar aponeuroses and apparently normal palmar aponeuroses residual strain and hysteresis loop increased significantly as a linear function of the amount of digested elastin. In contrast these biomechanical parameters were not affected significantly in contracture bands. In normal and apparently normal areas incubation with chondroitinase ABC resulted in a significant increase of residual strain and, as opposed to elastase, a decrease of normalized hysteresis loop. In contracture bands, however, these biomechanical parameters remained unchanged. RELEVANCE: The increasing evidence of a correlation between morphological changes of palmar elastin and ground substance with the progress of Dupuytren's disease emphasizes the need to determine the relative importance of these connective tissue components for the pathogenesis of Dupuytren's disease.

Journal Article↗
PubMed1995

Biomechanical properties of normal tendons, normal palmar aponeuroses and palmar aponeuroses from patients with Dupuytren's disease subjected to elastase and chondroitinase treatment.

Normal tendons, normal palmar aponeuroses and specimens from patients with Dupuytren's disease, namely apparently normal palmar aponeuroses and contracture bands were subjected to elastase and chondroitinase ABC digestion. Maximum Young's modulus, normalized hysteresis loop and residual elongation were determined before and after enzyme treatment. In normal tendons, normal and apparently normal palmar aponeuroses both normalized hysteresis loop and residual elongation increased significantly after elastase treatment, whereas the stiffness decreased. Normalized hysteresis loop and residual elongation display changes corresponding to the amount of digested elastin. The increased viscosity of untreated contracture bands containing less elastin, as compared to normal palmar aponeurosis, was not affected by elastase. Obviously, the elastic fibers in normal shape and distribution are responsible for maintaining an elastic status with a low viscous stress component. With the exception of contracture bands chondroitinase ABC caused a minor increase of residual elongation and as opposed to elastase a decrease of normalized hysteresis loop indicating an increased mobility of the tissue fibers.

Animals↗
PubMed1992

Symmetrically banded collagen fibrils: observations on a new cross striation pattern in vivo.

Collagen fibrils with a symmetric banding pattern, an as yet overlooked component of the extracellular matrix, were found in the reticular layer of the basement membrane of human sebaceous glands. In longitudinal sections this newly described banding pattern is D-periodic (D = 67 nm) resembling the period length of native type collagen fibrils. In cross sections the symmetrically banded fibrils are irregularly outlined. The period length and the symmetric banding pattern led to the assumption that collagen molecules are staggered by the distance D, similar to native type collagen fibrils, but are arranged antiparallel. This hypothesis was tested by antiparallel superposing transparent photocopies of native type fibrils. In addition, schematic drawings of the cross striation pattern of native type fibrils were superposed in reverse directions by means of computerized image-manipulation. A model of molecular alignment was evolved from these experiments, which is characterized by two features: 1) pairs of antiparallel collagen molecules are D-staggered and 2) the two molecules of a pair are slightly shifted from precise register. The proposed model is the only one correlating with the data obtained from direct measurements on symmetrically cross striated fibrils. The fibrils described in the present study represent a supramolecular aggregate of collagen previously not observed in vivo.

Basement Membrane↗
PubMed1992

Effects of monomeric acrylic embedding media on the antigenicity of two epitopes of the MIC2-encoded Ewing's sarcoma cell membrane antigen.

Comparative electron microscopic studies of pre- and postembedding immunolabeling experiments have shown that the antigenicity of some epitopes is lost during acrylic resin embedding of the respective tissues. In the present investigation we have tested the sensitivities of two embedding-labile epitopes (HBA-71 and HBA-45) of the Ewing's sarcoma-associated MIC2-encoded E2 antigen to the effects of the different treatment steps, which are necessary for the preparation of ultrathin sections. The extent of antigenic retention was quantitated using flow cytometry and enzyme-linked immunosorbent assays (ELISA) of tumor cell lines, thymocytes and cell membrane extracts. Fixation, dehydration and high temperature treatment of MIC2-positive cells showed only minor effects on the reactivity with the HBA-71 and HBA-45 antibodies. However, exposure of the cells to the monomeric acrylic resins LR White (LRW), LR Gold (LRG) and Lowicryl K4M at 4 degrees C for 2-18 h resulted in a significant reduction of the HBA-71 and HBA-45 reactivities. In contrast, the antigenicity of both epitopes was maintained during treatment with the apolar Lowicryl HM20 embedding medium under these non-polymerizing conditions. The resins have no direct effect on the HBA-71/HBA-45 antigen, since it could be extracted in intact form from membranes of native, but not of fixed, tumour cells using LRW for membrane solubilization. These data indicate that the HBA-71/HBA-45 antigen remains in the cell membrane and is indirectly influenced by the extraction/modification of adjacent membrane constituents. The adverse effects of the polymerization process, in the case of embedding at low temperature in Lowicryl HM20, destroyed MIC2-antigenicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗
PubMed1991

Biomechanical properties of elastase treated palmar aponeuroses.

Human palmar aponeurosis was treated with elastase in the presence or absence of soybean trypsin inhibitor. The removal of elastic fibers was complete as proved by electron microscopy. Cyclic loading was performed at a constant strain rate. Residual strain was measured and the stiffness and the fraction of dissipated energy of strain energy was calculated and compared to that of untreated samples of palmar aponeurosis. Residual strain and dissipated energy showed a dramatic increase after enzyme treatment, both in presence and absence of soybean trypsin inhibitor. Stiffness, on the other hand was reduced. The remaining collagen fibers show a more viscous behavior. Our results support the hypothesis that the elastin fibers are responsible for the elastic recovery, observed on specimens of untreated palmar aponeurosis.

Adult↗
PubMed1991

The monoclonal HBA-71 antibody modulates proliferation of thymocytes and Ewing's sarcoma cells by interfering with the action of insulin-like growth factor I.

The monoclonal HBA-71 antibody recognizes a Ewing's sarcoma associated antigen, which is also highly expressed on the cell surface of human cortical thymocytes and islets of Langerhans among normal tissues. The antibody was found to inhibit partially the growth of ES tumor cell lines and to trigger proliferation in thymocyte cultures. The influence of growth factors and the effect of the HBA-71 antibody was further investigated in the present study. The growth of ES tumor cells was demonstrated to be dependent on the presence of insulin-like growth factor I or insulin. The HBA-71 antibody (25 micrograms/ml) enhanced the growth stimulatory effect of IGF-I under serum-free conditions. The expression of the HBA-71 epitope is modulated positively by IGF-I and insulin and negatively by dexamethasone and human growth hormone in ES/PNET tumor cells and thymocytes. IGF-I either alone or in combination with HBA-71 stimulated the proliferation of thymocytes under serum-free conditions whereas in complete medium, IGF-I stimulated thymidine incorporation and the HBA-71 antibody either alone or in the presence of IGF-I showed inhibitory activity most likely due to down-regulation of the receptor. These data demonstrate the important role of IGF-I in the growth of ES/PNET tumor cells as well in the proliferative activity of HBA-71 positive normal thymocytes. The biological activity of IGF-I in malignant thymocytes, pancreas tumors, fetal muscle, brain, granulosa and Sertoli cells has been documented in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Quantitation of collagen fibril cross-section profiles in aging human veins.

The cross-section profiles and the diameter distribution of collagen fibrils were examined quantitatively in normal human internal jugular veins at different ages (first, fifth, and eighth decades). All fibrils showed a regular cross-striation pattern of native-type collagen fibrils irrespective of their cross-section profiles. Irregularly outlined ("dysplastic") fibrillar profiles were observed among the normally occurring circular cross-section profiles. The frequency of such unusual fibrils significantly increased with age. This increase was more pronounced in the tunica media as compared with the tunica adventitia. In the tunica media diameters of collagen fibrils also generally increased with age. In the tunica adventitia, on the other hand, fibrillar diameters were not significantly altered at different ages. The results of this study indicate that the frequency of both the irregularly outlined fibrillar cross-section profiles and increased fibrillar diameters depends on age in normal vascular walls. Therefore, it is concluded that the occurrence of "dysplastic" fibrils is a physiologic age-related phenomenon rather than a morphologic sign of pathologic alteration of collagen. The higher frequency of irregularly outlined collagen fibrils in the tunica media may indicate a higher and/or altered synthetic behavior of smooth muscle cells when compared with fibroblasts of the tunica adventitia.

Adult↗
PubMed1990

The effect of substance L on glucose-mediated cross-links of collagen in the diabetic db/db mouse.

Genetically diabetic mice (db/db) were given 50 mg/kg body weight/day substance L, a nontoxic basic amino acid and compared to control diabetic mice without treatment. The oral administration of the compound was started at the age of 3 months and the animals were sacrificed at the age of 7 months. No adverse effects were observed in animals given the substance L. Total food consumption, drinking water intake and body weight were comparable between the groups. Nonenzymatic glycosylation of serum proteins and hemoglobin was not significantly different in the groups. Renal pathological lesions in the control diabetic mice showed glomerular mesangial expansion and on electron microscopy thickened glomerular basement membranes with a mean thickness of 3,204 +/- 186 A. Treated animals showed significantly less mesangial crescents and thinner glomerular basement membrane thickness of 2,520 +/- 252 A (p less than 0.01). The experimental animals showed in addition a lower mean kidney weight. Glomerular but not tubular proteinuria was reduced in the treated group. Basement membrane collagen type IV isolated from kidneys of experimental animals was more soluble in acidity and showed a lower degree of cross-linking as evaluated by SDS-polyacrylamide gel electrophoresis. We conclude that substance L is beneficial to diabetic renal changes. We suggest that this positive effect could be due to the inhibition of glucose-mediated abnormal cross-linking of collagenous structures by the interaction of substance L with reactive carbonyl residues of glycosylation adducts of collagen. Other possible mechanisms are discussed.

Administration, Oral↗
PubMed1989

Ewing's-sarcoma-associated HBA-71 tumor antigen represents a new differentiation marker of human thymocytes.

The monoclonal HBA-71 antibody recognizes a new human tumor-associated antigen of Ewing's sarcoma and peripheral neuroectodermal tumors, which is also expressed in some normal tissues, including thymus, islets of Langerhans, ependyme, adenohypophysis, Sertoli/Leydig and granulosa cells. Besides a tumor-specific reciprocal chromosomal translocation t (11:22), the expression of the HBA-71 antigen is the only marker which can be used for reliable differential diagnosis of these rare malignancies of childhood and adolescence among other small round cell tumors. The HBA-71 antigen is further characterized here by ultrastructural, functional and cell-matrix interaction studies. In immunohistochemical staining the HBA-71 reacted with the cell surface of human cortical thymocytes. The HBA-71 antigen was also found to be localized at the cell-surface glycocalyx of tumor cells using immunogold staining and electron microscopy. A panel of additional monoclonal antibodies with reactivity patterns similar to those of the HBA-71 antibody was obtained by immunization of mice with ES cell lines and boostering with thymocytes. The HBA-71 antibody triggers proliferation of thymocytes and to a lesser extent also stimulates peripheral mononuclear blood cells. Antibody-induced thymocyte cultures exhibit the phenotype of immature, CD3low thymocytes with uniform and stable expression of the HBA-71 antigen. In contrast to the thymocytes the HBA-71 antibody has an inhibitory effect on the continuous growth of the HBA-71+ tumor cell lines. The HBA-71 antigen may be involved in the regulation of growth of the positive normal and malignant tissues. Positive modulation of the antigen expression was induced in Ewing's sarcoma cell lines in response to insulin, insulin-like growth factor I (IGF-I) and by interaction of the cells with the extracellular matrix.

Animals↗
PubMed1989

Expression of a new human THY-1 related antigen in Ewing's sarcoma and peripheral neuroectodermal tumors.

Ewing's sarcoma (ES), peripheral neuroectodermal tumor (PNET) and Askin's tumor of the chest wall share a reciprocal chromosomal translocation between the long arms of chromosomes 11 and 22 (q23-24; q12). In the absence of other distinguishing features this specific translocation is regarded as marker of a common and neuroectodermal origin for these rare tumors. A monoclonal antibody (HBA-71) developed in our laboratory has been found to recognize an unique ES and PNET associated antigen, which is also expressed in some normal tissues, including thymus, bone marrow, islets of Langerhans, ependyma and adenohypophysis. It is shown in this study that this HBA-71 antigen is closely related to the murine THY-1 antigens, major cell surface glycoproteins of thymocytes and brain in mice and rat. Both antigens have similar molecular ratios (18,000), amino acid compositions and sensitivity to tryptic digestion, show high cell surface expression, and binding of the appropriate antibodies to HBA-71 antigen triggers proliferation in thymocytes. The HBA-71 epitope may represent a primitive neuroectodermal marker of ES/PNET, or its expression may be directly linked to the reciprocal translocation invariably associated with HBA-71-positive ES and PNET tumors, which maps to the same region of chromosome 11 (q23-24) as the human Thy-1 gene.

Amino Acids↗
PubMed1988

Amianthoid (asbestoid) transformation: electron microscopical studies on aging human costal cartilage.

The present study reports on the fine structure of human costal cartilage at different ages in order to obtain information on the morphogenesis of amianthoid fibers. Our results reveal an overall increase of collagen fibril diameter with increasing age, even in areas with no signs of amianthoid transformation. Ultrastructural evidence is presented that this increase in diameter is due to a gathering of the preexisting collagen fibrils. The age-related change in collagen fibril diameter is paralleled by changes in the composition and ultrastructural appearance of cartilage proteoglycans (as revealed by acridine orange staining). Acridine-orange-positive filaments indicative for proteoglycans are markedly reduced in size with advancing age in centrally located regions of costal cartilage. Treatment with testicular hyaluronidase previous to acridine-orange staining leaves these small proteoglycan filaments unaffected. By contrast, the filaments visible after acridine-orange staining in the extracellular matrix near to the perichondrium are susceptible to hyaluronidase treatment. Infrequently, a sharp increase in collagen fibril diameter can be observed in territorial matrix areas of degenerating chondrocytes. This observation is conspicuous at ages of 10 and 20 years. Amianthoid transformation is characterized by the appearance of collagen fibrils strictly arranged in parallel. These amianthoid fibers are embedded in a matrix rich in small acridine-orange-positive filaments similar to the proteoglycan filaments observed in centrally located matrix regions. It can be concluded that extensive remodelling not only of the collagen fibrils but also of the cartilage proteoglycans is involved in the development of amianthoid transformation.

Adult↗
PubMed1988

Reaggregation behavior of different types of collagen in vitro: variations in the occurrence and structure of dimeric segment long-spacing collagen.

Segment long-spacing collagen (SLS) can be precipitated from solutions of collagen using ATP as the inducing agent. Dimeric SLS aggregates have been observed in addition to monomeric SLS. We have compared collagen types I, II, III, and V with respect to their ability to form dimeric SLS in vitro. These collagen types were isolated from bovine tissues and characterized by polyacrylamide slab gel electrophoresis of the respective alpha-chains. Only monomeric SLS can be detected in preparations of collagen types I and III. Dimeric SLS, on the other hand, accounts for the majority of the crystallites seen in preparations of collagen types II and V. Dimeric SLS from both collagen types II and V reveal overlap zones at the carboxy-terminal ends of the collagen molecules. However, dimeric SLS from collagen types II and V differ with respect to their overlap distances. Significant portions of the triple helical domains of collagen molecules are occupied by the overlap region of dimeric SLS from type II collagen. On the other hand, dimeric SLS from type V collagen is composed of molecules overlapping only at their short nonhelical telopeptides. It is concluded that the ability of collagen molecules to aggregate into dimeric SLS under defined experimental conditions is collagen type dependent.

Adenosine Triphosphate↗
PubMed1988

Structural and functional changes in lung tissue of mice fed with beta-aminopropionitrile fumarate, L-3-cis-hydroxyproline, and L-4-cis-hydroxyproline.

Structural and functional changes in lung tissue of mice fed with beta-aminopropionitrile fumarate, L-3-cis-hydroxyproline, and L-4-cis-hydroxyproline. We fed 0.1% solutions of 3-cis-hydroxyproline (3cisHP), 4-cis-hydroxyproline (4cisHP) or beta-aminopropionitrile fumarate (beta APN) to 5-week-old mice for 1 month and studied the effect of each of these substances on the lung function and structure. Compared to control animals the compliance of the respiratory system in the mean was increased by 3-15% in the mice fed beta APN or 3cisHP, and decreased by 2-8% in the mice fed 4cisHP. On electron microscopial examination no overt morphological changes were detectable although as proven by biochemical analysis 3cisHP and 4cisHP were incorporated into the collagen of the mice who received these substances. We conclude that the effect of substances interfering with the normal production of collagen molecules depends on the kind of collagen affected and on the rate of collagen turnover.

Aminopropionitrile↗
PubMed1987

Histochemistry of the extracellular matrix of aging hyaline cartilage.

Cartilage proteoglycans (PGs) exhibit marked structural changes with increasing age. There is an increase in small PGs rich in KS as compared to larger PGs rich in chondroitin sulfate (CS) with increasing age. In the present study investigations have been performed to obtain more detailed information about the distribution of different glycosaminoglycans (GAGs). Changes were observed in the interterritorial matrix by means of ultrastructural visualization of PGs with acridin orange. The changes in the ultrastructural organization of the interterritorial matrix of costal cartilage are followed by significant changes in its mechanical properties.

Acridine Orange↗
PubMed1986

Histochemistry of glycosaminoglycans in cartilage ground substance. Alcian-blue staining and lectin-binding affinities in semithin Epon sections.

The critical-electrolyte-concentration staining method using Alcian blue (AB) was applied to etched semithin Epon-embedded sections. The distribution of various glycosaminoglycans (GAGs) was studied in hyaline, elastic, cellular and fibrous cartilage obtained from humans and rodents. The staining patterns in semithin sections were found to correspond to those obtained using paraffin-embedded material. Lectin histochemistry was performed on consecutive sections. The following peroxidase-labelled lectins were used: Ricinus communis A I, Arachis hypogaea, Ulex europaeus A I, Triticum vulgaris, Helix pomatia, Limax flavus, and concanavalin A. The lectin-binding capacity of cartilaginous ground substance was found to be low, as was expected on account of the few free sugar residues of GAGs. Chondroitin sulphate, the most widely distributed GAG, did not exhibit lectin staining. The lectin-binding sites (positive staining for all lectins tested except H. pomatia) observed corresponded to areas positive for keratan sulphate, as shown by AB staining in preceding or following sections. The pronounced lectin binding seen in cellular structures and the inner territorial matrix regions is considered to be due to higher concentrations of oligosaccharides involved in the metabolism of GAGs.

Alcian Blue↗
PubMed1985

Differentiation of extracellular matrix in the cellular cartilage ("Zellknorpel") of the mouse pinna.

Differentiation of cellular cartilage was studied in the mouse pinna with particular reference to matrix material. Fixation of glycosaminoglycans was performed by the use of acridine orange and elastin was identified by staining thin sections with tannic acid and uranyl acetate. Condensation of mesenchymal cells ("prechondroblasts") initiates the formation of a blastema of cartilaginous tissue at postnatal day 4. The synthesis of acidic glycosaminoglycans begins at postnatal day 8 when prechondroblasts transform to chondroblasts. Glycosaminoglycans can be detected within secretory vesicles of chondroblasts at postnatal day 8, in the extracellular space at postnatal day 13. Delicate collagen fibrils and elastic fiber microfibrils are seen between prechondroblasts and chondroblasts. Deposition of elastin begins at postnatal day 11. A network of elastic fibers and lamellae is formed, which replaces both collagen fibrils and elastic fiber microfibrils. In the interstice of mature cellular cartilage only elastin and proteoglycans are present (postnatal day 21). These findings indicate that cellular cartilage represents an independent kind of supporting tissue, which may serve as a progenitor of hyaline or elastic cartilage ("transitional cellular cartilage") but does not differentiate from hyalin cartilage.

Animals↗