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Biomedical subjects

K Weber

Publications and source records attributed to K Weber.

At least 487 records · Page 27Linked to original sources
PubMed1984

[Clinical aspects and etiology of acrodermatitis chronica atrophicans].

We followed up nine patients with acrodermatitis chronica atrophicans (ACA) for an average of 2 years (6-44 months). Extradermal symptoms were observed in five patients, three of whom developed systemic signs such as fatigue or general sensitivity to cold; three suffered from cardiac symptoms; and two had joint and/or nervous system involvement. In one patient, erythema migrans and oligoarthralgia preceded the ACA. In most patients, the laboratory tests showed changes often seen in inflammatory diseases; we found an elevation of IgA, IgG and/or IgM in five patients. Using an indirect immunofluorescence test with Ixodes dammini spirochetes as antigen, the patients had more or less elevated IgG antibody titers and insignificant IgM antibody titers; similar results were obtained in some patients when an Ixodes ricinus spirochete isolated in the area of Munich was used as antigen. We believe that ACA is a chronic spirochetosis with manifestations present in the skin, joints, nervous system, and presumably in the heart.

Acrodermatitis↗
PubMed1984

Monoclonal antibodies specific for vimentin.

Previously described vimentin monoclonal antibodies recognize other cellular or intermediate filament proteins in addition to vimentin. In contrast the set of murine monoclonal antibodies described here and elicited using porcine vimentin as antigen appear specific for vimentin. All seven antibodies react only with vimentin in "immunoblot" analysis on gel electrophoretically separated polypeptides from total cell extracts. They do not recognize other closely related intermediate filament proteins including desmin and GFA (glial fibrillary acidic protein). Immunofluorescence microscopy on tissue sections shows a positive reaction in connective tissue, endothelial cells, vascular smooth muscle cells and astrocytes. Typical intermediate filament profiles are documented in fibroblasts and in other cultured cells known to contain vimentin. Although all antibodies react with human and porcine vimentin some show species-specific restriction when rat, mouse and chicken vimentin are used. These results, together with different IgG types and certain aspects of the staining patterns, allow a subdivision of the antibodies. The vimentin antibodies described here complete a set of monoclonal antibodies each specific for only one intermediate filament protein type. Their reaction on human material allows their use in pathology to determine the histogenetic origin of neoplasms.

Animals↗
PubMed1984

The intermediate filament complement of the retina: a comparison between different mammalian species.

We compared the intermediate filament expression of the various cell types in the fully differentiated neural retina from rat, mouse, rabbit, guinea pig, cow, pig, and cat. Many cell types had an intermediate filament complement conserved across species boundaries, such as Müller cells and retinal ganglion cells. In some species (rabbit, guinea pig, and cow), however, we were unable to visualize GFA (glial fibrillary acidic)-positive retinal astrocytes, although such profiles were clearly visible in the remainder. Horizontal cell staining proved to be extremely species-variable. In rat and mouse the processes of these cells were identically displayed with antibodies to vimentin and all three neurofilament triplet proteins. In cow they decorated with antibodies to vimentin and antibodies to the two lower molecular weight neurofilament proteins alone, whereas in pig, rabbit and guinea pig all three neurofilament proteins but not vimentin were present. Finally cat horizontal cells stained for all three neurofilament proteins, some finer processes being additionally stainable with vimentin. A further surprise was the visualization of profiles positive only for the two lower molecular weight neurofilament proteins in the inner nuclear layer of both rabbit and guinea pig retina but not the other species. The implications of these results will be discussed.

Animals↗
PubMed1983

Proteolysis of the neurofilament 68 kDa protein explains several previously described brain proteins of unique composition and high acidity.

Neurofilaments follow the structural principles of non-neuronal intermediate filaments but contain additional sequences which are carboxyterminally located and increase in length between triplet proteins (68 kDa, 160 kDa and 200 kDa). The tailpiece domain has been sequenced in the case of the porcine 68 kDa protein. It has a unique amino acid composition. Within 106 residues there are only 12 different amino acid types, and glutamic acid accounts for 46% of the sequence. Examination of the literature on highly acidic brain proteins leads us to the proposal that microglutamic acid-rich protein, Glu-50, macroglutamic protein, as well as some unusual components of the S100 class, are most likely proteolytic degradation products of the neurofilament 68 kDa protein.

Amino Acid Sequence↗
PubMed1983

Amino acid sequence characterization of mammalian vimentin, the mesenchymal intermediate filament protein.

The amino-terminal 98 residues of porcine vimentin have been determined by amino acid sequence studies. Extensive overlap is seen with the corresponding region of the carboxyterminal 448 residues of hamster vimentin predicted from DNA sequence studies, which left the very amino-terminal region unknown. The combined data show that contrary to gel electrophoretic results, mammalian vimentin contains only about 467 residues, and that species-specific drift occurs mainly in the amino-terminal non-alpha-helical array. The results are discussed parallel to emerging concepts on intermediate filament protein diversity.

Amino Acid Sequence↗
PubMed1983

[Erythema migrans disease. A contribution to its clinical features and relation to Lyme disease].

A largely prospective study averaging 33 months was undertaken in 30 patients with and one without (chronic) erythema migrans. In one case erythema migrans disappeared spontaneously, in the 29 others it persisted up to six months, but quickly responded to antibiotic treatment. Measured from the tick bite in 9 patients or from onset of the erythema migrans, arthritis and arthralgia appeared in ten patients on average 6.5 months (0.7-36), and persisted for eight months (0.2-42). In seven of these patients sensory disturbances appeared three weeks (1-10) later and (or) signs of meningitis which lasted for four months (0.5-16), while in three patients cardiac symptoms appeared a few weeks later, persisting for 4.5 months (0.3-12). In one patient tracheolaryngitis developed two months later, persisting for three months. These manifestations occurred in seven patients despite antibiotic treatment. Extradermal manifestations in two patients were successfully treated with high parenteral penicillin doses, in one instance followed by tetracyclin. "Erythema migrans disease", differing from Lyme disease described in the U.S.A. in only a few aspects, apparently cannot be successfully treated with low oral doses of penicillin, but can in certain circumstances be favourably influenced by high parenteral doses of penicillin G.

Adolescent↗
PubMed1983

Mapping the fodrin molecule with monoclonal antibodies. A general approach for rod-like multidomain proteins.

Fodrin is an axonally transported F-actin crosslinking rod-shaped multidomain protein having a length of 200 nm. It is though to be related to erythroid spectrin (220,000 and 240,000 Mr) as it is built as a tetramer derived from a heterodimer comprised of two large subunits (235,000 and 240,000 Mr). A panel of 24 monoclonal antibodies has been used to probe the fodrin structure by direct microscopical decoration and identification of large tryptic fragments retaining antigenicity. The combined results unambiguously define the fodrin organization and show it to be strongly related to erythrocyte spectrin. They demonstrate the heterodimer organization, the head-to-head association of dimers, the protease-resistant domain structure of each subunit and indicate that different termini of the polypeptides are localized at the free F-actin binding ends and the heterodimer association sites. They also show that within the same mammalian species even the highly related 240,000 Mr subunits of fodrin and spectrin are immunologically distinct, most likely reflecting different gene products.

Animals↗
PubMed1983

Ligand-induced conformational changes in villin, a calcium-controlled actin-modulating protein.

The physical structure of villin, a Ca2+-modulated regulator protein of actin filament organization, has been studied in the absence and presence of Ca2+ using analytical ultracentrifugation, gel chromatography, ultraviolet difference spectroscopy, and circular dichroism. Villin exhibits an intrinsic sedimentation coefficient, S020, w, of 5.0 s and an apparent Stokes radius, Rs, of 44 A in EGTA-containing buffer. In the presence of greater than 20 microM Ca2+, villin shows a S020, w of 4.1 s and Rs of 49 A, indicative of a conformational change in the protein. No significant changes in the partial specific volume (0.73) of villin are observed in the presence of Ca2+, and sedimentation equilibrium studies demonstrates that the effects of Ca2+ are not due to a change in the molecular mass (95,000 daltons). The combined hydrodynamic data suggest that villin is an asymmetric molecule with an axial ratio of 4.5:1, based on a prolate ellipsoid model at 0.5 g/g of hydration, corresponding to a maximum length of 84 A. The presence of Ca2+ changes the shape to a more asymmetric molecule with an axial ratio of 8:1 and a maximum length of 123 A. Since the large proteolytic fragment, villin core, does not exhibit the strong structural change of villin, an important function of the small villin headpiece domain in the observed conformational change of intact villin is suggested. The results indicate new aspects of the function of villin as cross-linker in microvillus core filament bundles and the disintegration of these structures in the presence of calcium.

Actins↗
PubMed1983

Demonstration of three distinct calcium-binding sites in villin, a modulator of actin assembly.

Villin, a Ca2+-modulated F-actin-binding protein (95,000 daltons) present in microvillus core filament bundles, has been shown to contain multiple Ca2+-binding sites. 45Ca Hummel-Dreyer chromatography reveals the presence of two rapidly exchanging Ca2+-binding sites with an apparent dissociation constant, Kd, equal to 4.6 X 10(-6) M. Use of the two proteolytically separable domains of the molecule revealed that one site is located on the 90,000-dalton core (apparent Kd = 3.5 X 10(-6) M) while the second site is provided by the 8,800-dalton headpiece fragment (apparent Kd = 7.4 X 10(-6) M). In addition villin displays a further very slowly exchanging or nonexchangeable high affinity Ca2+-binding site, which is situated in the core domain. Secondary structural predictions and a comparison of the amino acid sequence of headpiece with other known Ca2+-binding proteins indicates one region suggestive of a Ca2+-binding site, although headpiece seems not to exhibit a classical "EF-hand" Ca2+-binding structure.

Amino Acid Sequence↗
PubMed1983

Neurofilament architecture combines structural principles of intermediate filaments with carboxy-terminal extensions increasing in size between triplet proteins.

Mammalian neurofilament triplet proteins (68 K, 160 K and 200 K) have been correlated by a biochemical, immunological and protein chemical study. The 160 K and 200 K triplet proteins are intermediate filament proteins in their own right, since they reveal the alpha-helical coiled-coil rod domain analyzed in detail for the 68 K protein. Triplet proteins display two distinct arrays. Their amino-terminal region built analogously to non-neuronal intermediate filament proteins should allow a co-polymerization process via the interaction of coiled-coil domains. The extra mass of all triplet proteins is allocated to carboxy-terminally located extensions of increasing size and unique amino acid sequences. These may provide highly charged scaffolds suitable for interactions with other neuronal components. Such a domain of 68 K reveals, in sequence analysis, 47 glutamic acids within 106 residues. The epitope recognized by a monoclonal antibody reacting probably with all intermediate filament proteins has been mapped. It is located within the last 20 residues of the rods, where six distinct intermediate filament proteins point to a consensus sequence.

Amino Acid Sequence↗
PubMed1983

Amino acid sequence data on glial fibrillary acidic protein (GFA); implications for the subdivision of intermediate filaments into epithelial and non-epithelial members.

Determination of 50% of the sequence of the astrocyte-specific intermediate filament (IF) protein documents the hypervariable regions as well as parts of the coiled-coil array of glial fibrillary acidic protein (GFA). The results show that the four non-epithelial IF proteins (myogenic desmin, mesenchymal vimentin, GFA and neurofilament 68 K protein) known to form homopolymers are much more closely related than the epithelial keratins, which seem to form heteropolymers only. Of the four non-epithelial proteins, desmin and vimentin are the most closely related, since GFA has a shorter non-alpha-helical array at the amino terminus. We discuss the possibility that the non-alpha-helical terminal arrays, because of their sequence and length variability, are responsible for differences of distinct IF with respect to physical-chemical properties such as the low ionic strength-induced depolymerization into protofilaments.

Amino Acid Sequence↗
PubMed1983

Monoclonal antibodies to desmin, the muscle-specific intermediate filament protein.

A set of monoclonal antibodies to desmin has been isolated from a fusion of mouse myeloma cells with spleen cells from mice immunized with purified porcine desmin. Eleven group I antibodies recognized desmin in the immune blot, and using defined desmin fragments the epitope has been tentatively assigned as lying between residues 325 and 372. When cell lines were tested in immunofluorescence only the human line RD and hamster BHK-21 were positive. When tissue sections were used, skeletal, cardiac, visceral and some vascular smooth muscle cells were positive. Thus, the group I antibodies appear specific for desmin and do not recognize other intermediate filament proteins. Group II monoclonals recognized not only desmin in the immune blot but also other polypeptides. The epitope of this class is located between residues 70 and 280. In immunofluorescence on cell lines and tissues, the staining patterns of group II antibodies were more complicated and demonstrate that not only other intermediate filament proteins but also additional antigenic determinants are being recognized. The group I antibodies stain, as expected from their desmin specificity, rat and human rhabdomyosarcomas and thus appear to be useful reagents in pathology.

Animals↗
PubMed1983

Malignant melanomas contain only the vimentin type of intermediate filaments.

Six malignant melanomas have been examined for the type of intermediate filament they contain. All six cases showed positive staining of intermediate filaments with antibodies to vimentin, with cells containing large numbers of melanosomes being stained less strongly in general. The tumor cells did not react with antibodies to keratin, desmin, neurofilaments or glial fibrillary acidic protein. Thus typing of intermediate filaments can distinguish melanoma from undifferentiated carcinoma, but not from lymphoma or sarcoma. Since melanocytes are known to be vimentin positive, and since most of the samples we studied were from metastases, these results are a further indication that the intermediate filament type typical of the parental cell is retained in the metastases, as well as in the primaries of solid tumours. The implications of vimentin positivity for the histiogenesis of the melanocyte are also discussed.

Cytoskeleton↗
PubMed1983

Vimentin filaments in peritoneal macrophages at various stages of differentiation and with altered function.

Comparative immunofluorescence microscopic, transmission and scanning electron microscopic investigations were carried out to study the arrangement and significance of vimentin filaments in monocytes, macrophages, epithelioid cell equivalents and multinucleate giant cells under various different functional conditions, and in the presence of functional disorders. Uncoated or sebum-coated coverslips were implanted in the peritoneal cavity of Wistar rats. Some of the animals received repeated i.p. injections of colchicine. Rats were killed at various times 1 to 14 days after initiation of the experiment. The number of macrophages, the degree of their activation, and the growth of cells on the coverslips was considerably greater on sebum-coated than on uncoated implants. Various characteristic vimentin distribution patterns were found dependent on the cell cycle, the form and volume of the cell, and on the degree of differentiation and maturity; they were also related to the type and intensity of cell function. These patterns were best developed in ordered multinucleate giant cells. Repeated administrations of colchicine resulted in a marked flattening of the cell body on the coverslips--which correlated with a considerable reduction in the number of vimentin filaments and of cytoplasmic processes--and also in the formation of circumscribed erect, tree-like protuberances. The "trunk" of these structures comprised closely bundled vimentin filaments, and the cell nucleus was located at its base. These morphologic changes, which were associated with a functional insufficiency, proved to be reversible.

Animals↗
PubMed1983

Calcium control of actin-myosin based contraction in triton models of mouse 3T3 fibroblasts is mediated by the myosin light chain kinase (MLCK)-calmodulin complex.

Triton extraction of mouse 3T3 cells provides cellular models able to contract in a Ca2+-dependent manner upon exposure to MgATP. Such models reveal myosin kinase (MLCK) along their microfilaments and contraction is inhibited by antigen affinity-purified antibodies to gizzard MLCK. When extraction is performed at higher salt concentrations the models become non-contractile and immunofluorescence microscopy fails to detect the kinase. Inactive models can be functionally reactivated by exposure to exogenously provided purified kinase plus calmodulin present in the normal buffer. Reconstituted models again reveal microfilament-associated kinase. Functional reconstitution requires both the addition of kinase and calmodulin and does not occur in the presence of trifluoperazine. The combined results indicate that contractility of non-muscle cellular models is controlled by calmodulin-dependent MLCK acting on the actin-myosin-containing microfilaments with a calcium control exerted in the phosphorylation step of myosin.

Adenosine Triphosphate↗