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K Weber

Publications and source records attributed to K Weber.

At least 379 records · Page 21Linked to original sources
PubMed1988

[Immunochemical analysis of the immune response in late manifestations of Lyme borreliosis].

Compared to American strains, European Borrelia burgdorferi strains revealed considerable heterogeneity of major proteins. Four strains isolated from ticks, human skin and human CSF were selected from our 23 Borrelia burgdorferi isolates. These strains and the American type strain B31 were characterized by SDS-PAGE (Coomassie Blue staining) and Western blots (using rabbit immune sera against two of the strains and two monoclonal antibodies (H5323 and H3TS) against a major outer surface protein (OspA]. The strains showed considerable differences in SDS-PAGE pattern. Corroborating the results of a previous study, we could demonstrate that the OspA (31/32K) can change from a minor to a major protein and in reverse the pC (21/22K) from a major to a minor protein during subculturing. Moreover, European strains can antigenically differ in OspA, pC and also in a further low molecular weight protein of 17/18K. To examine whether the antigenic heterogeneity of European isolates is reflected in the immune response of European patients we examined sera from patients with late manifestations of Lyme Borreliosis by Western blot using the five strains as antigens. Sera from seven patients with acrodermatitis chronica atrophicans (ACA) showed a surprisingly strong reactivity with the skin isolate. All sera had antibodies against the 17/18K protein of the skin isolate, but none was reactive with the analogous 17/18K of the other strains. On the other hand a comparable predominance of one strain was not found testing sera from patients with Lyme arthritis. One patient even had antibodies against OspA and OspB proteins of strain B31. Contrary to findings in American Lyme Disease antibodies against the OspA were rarely observed in the sera of our patients (only one patient had such antibodies) although we tested the patients sera with five different strains. Only two patients had stronger reactions with the skin isolate. These findings suggest that ACA is caused by antigenically closely related Borreliae. This could explain the finding that ACA is rarely observed in the US (US strains are antigenically closely related to strain B31). Our findings in patients with Lyme Arthritis--on the other hand--suggest that "different serotypes" can cause Lyme Arthritis. This does not exclude the possibility that Borrelia proteins are an important factor in the pathogenesis of Lyme arthritis. Finally the differences in reactivity of sera with different strains in the Western blot led us to examine whether such differences are also found in serodiagnostic tests using different strains as antigens.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Nebulin and titin expression in Duchenne muscular dystrophy appears normal.

Monoclonal antibodies which recognize different epitopes on either titin or nebulin show normal staining patterns on frozen sections of three muscle biopsies of Duchenne muscular dystrophy (DMD). Gel electrophoresis and immunoblotting performed on two of these muscle biopsies show the normal pattern of titin and nebulin polypeptides. Since the donor of one of these biopsies has a large deletion of the 5'-region of the DMD gene, our results argue against the recent proposal that nebulin is the gene mutated in DMD.

Antibodies, Monoclonal↗
PubMed1987

Location and sequence characterization of the major phosphorylation sites of the high molecular mass neurofilament proteins M and H.

Diagonal fingerprinting allows the specific purification of those tryptic peptides which change electrophoretic mobility due to a dephosphorylation step introduced after the first dimension. Nine tryptic peptides from the tail domain of porcine neurofilament M protein identify a minimum of 6 phosphorylated serines. Unexpectedly, four of the nine peptides characterize a region of degenerate repetitive sequences. Results on neurofilament H tail, although less complete, yield longer sequences of degenerate repetitive character. Here, all serines present appear to be contained in a lysine-serine-proline unit. This motif also occurs in some but not all M peptides. We suggest that degenerate repetitive sequences in neurofilament M and H tails have a high species-specific drift.

Amino Acid Sequence↗
PubMed1987

Calcium binding protein from porcine intestine binds to phosphatidylserine vesicles in the presence of calcium.

Protein II, a 32K cytoskeleton-associated protein isolated from porcine intestinal epithelium, binds to vesicles composed of phosphatidylserine in the presence, but not the absence, of 10 microM Ca2+. Binding was saturable and was specifically inhibited by chelation of free Ca2+ with EGTA. Binding was also inhibited by trifluophenothiazine. Vesicles composed of dimyristoylphosphatidylcholine did not bind protein II, suggesting that interaction with phosphatidylserine was selective. These properties are consistent with a possible role for protein II in Ca-regulated cytoskeleton-cell membrane events.

Animals↗
PubMed1987

Intermediate filaments in cytological specimens of thyroid tumors.

Cytological specimens of thyroid carcinomas and follicular adenomas obtained by fine-needle aspiration biopsies or touch imprints were investigated with antibodies to keratin, vimentin, and neurofilaments. All tumors were keratin positive. In follicular adenomas as well as in papillary thyroid carcinomas, a coexpression of keratin and vimentin was detected; in follicular carcinomas, only some tumors showed coexpression of keratin and vimentin; and in medullary thyroid carcinomas, positive staining of all six tumors studied was seen with the keratin and neurofilament antibodies, with some tumors also showing coexpression of vimentin. The mechanisms of such coexpression is unclear.

Adenocarcinoma↗
PubMed1987

The amino acid sequence of protein II and its phosphorylation site for protein kinase C; the domain structure Ca2+-modulated lipid binding proteins.

Protein II isolated from porcine intestinal epithelium is a Ca2+-modulated lipid-binding protein. The amino acid sequence of porcine protein II reported here sheds new light on the properties of a multigene protein family which includes the tyrosine kinase substrates of the sarc gene (p36) and of the EGF-receptor (p35). The sequence consolidates the structural principle in which an amino-terminal tailpiece of variable length is followed by a core built from four internally homologous segments for those proteins in the 35-40 kd range. Sequence data also show that the core can now be described as two domains each containing one low and one high homology segment. This view accounts for two Ca2+ sites, lipid aggregation and F-actin bundling--when present--and suggests that properties of the cores in which protein II differs from p36 and p35 arise primarily from segments 1 and 2. The protease-sensitive tailpiece of protein II is very short and lacks the phosphorylatable tyrosine present in the larger tail domains of p36 and p35. It harbors, however, like the p36 domain, the major site for in vitro phosphorylation by the Ca2+- and lipid-activated protein kinase C. In protein II this site is most likely threonine 6. The sequence alignment also explains why protein II does not interact with a unique p11, a property probably specific for p36. Our results further suggest that liver endonexin may reflect two protein species both closely related to protein II.

Amino Acid Sequence↗
PubMed1987

Intermediate filament expression in human vascular smooth muscle and in arteriosclerotic plaques.

Different regions of human aorta and of other human arteries obtained at autopsy were analyzed with regard to their topography and to the different stages of arteriosclerosis. Material was studied by immunocytochemical techniques with antibodies specific for either desmin (D) or for vimentin (V), the two types of intermediate filament proteins present in vascular smooth muscle cells. In normal arteries endothelial cells as well as the adjacent intimal cells were D-V+. In the media D+V+ as well as D-V+ cells were present, with the relative numbers of each cell type dependent on the particular blood vessel. When cells in arteriosclerotic plaques at different stages of development were examined an occasional plaque showed cells of the D+V+ type. In the majority of plaques however the cells were V-D+. In plaques where severe ulceration and necrotic material was present D-V+ cells were found at the border of the lesion: foam cells when they could be identified appeared to be D-V+.

Adult↗
PubMed1987

Cytoplasmic intermediate filament proteins and the nuclear lamins A, B and C share the IFA epitope.

The murine monoclonal antibody IFA isolated by Pruss et al. (Cell 27 (1981) 419) reacts with all major proteins of the cytoplasmic intermediate filament family (IF) albeit with different affinities but leaves the nucleus undecorated in standard immunofluorescence microscopy. Here we show that IFA reacts with all three nuclear lamins from rat and man in immunoblotting. This is most easily demonstrated in a cell line in which most cells lack cytoplasmic IFs. Thus the rather minor but ubiquitous 66 kD polypeptides identified by Pruss et al. as IF-associated proteins reflect the lamin triplet. While surprising at first, these results are in agreement with the approximate location of the IFA epitope on IF molecules and the recently discovered sequence homology along the rod domain between lamins A and C and IF proteins. Our results extend this relation to lamin B in spite of its unique behaviour during mitosis.

Animals↗
PubMed1987

Antibiotic therapy in early erythema migrans disease and related disorders.

Between December 1978 and July 1985, we used various antibiotics for the treatment of 97 adult patients with early erythema migrans disease (EMD). Six patients with borrelial lymphocytoma (BL) and 20 with acrodermatitis chronica atrophicans (ACA) were treated similarly. Follow-up was for a median of 20, 14, and 12 months, respectively. The erythema migrans and all associated symptoms resolved within a median of 3 weeks (0.5-18.4), BL within 7 weeks (4-16), and ACA partly or completely within several months. A Jarisch-Herxheimer (-like) reaction was observed in 8 patients with EMD. Fourteen patients with EMD and one with ACA developed an exacerbation of symptoms or new manifestations between the 2nd and 20th day, and 28 patients with EMD and one with ACA continued to have or acquired various symptoms greater than or equal to 3 weeks after initiation of therapy. Arthralgia, neurologic and constitutional symptoms, and in one instance a slight pulmonary interstitial edema developed in EMD. More severe initial illness was a risk factor for the development of later symptoms in EMD. Retreatment was more often necessary in ACA than in EMD. A patient with ACA had a recurrence after 5 1/2 years. IgG antibody titers rose at least fourfold in 5 patients with ACA and in 1 with EMD despite therapy. We tentatively recommend minocycline or high doses of parenteral penicillin for the treatment of these disorders.

Acrodermatitis↗
PubMed1987

Binding of two desmin derivatives to the plasma membrane and the nuclear envelope of avian erythrocytes: evidence for a conserved site-specificity in intermediate filament-membrane interactions.

Using solution binding assays, we found that a 45-kDa fragment of desmin, lacking 67 residues from the N terminus, could specifically associate with avian erythrocyte nuclear envelopes but not with plasma membranes from the same cells. It was also observed that a 50-kDa desmin peptide, missing 27 C-terminal residues, retained the ability to bind to both membrane preparations. Displacement experiments with an excess of purified vimentin suggested that the two desmin derivatives were interacting with a previously identified vimentin receptor at the nuclear envelope, the protein lamin B [Georgatos, S. & Blobel, G. (1987) J. Cell Biol. 105, 117-127]. Additional analysis by affinity chromatography confirmed this conclusion. Employing an overlay assay, we demonstrated that the 50-kDa fragment, but not the 45-kDa desmin peptide, was capable of interacting with the plasma membrane polypeptide ankyrin (a known vimentin attachment site), as was intact vimentin. Conversely, the nuclear envelope protein lamin B was recognized by both fragments but not by a chymotryptic peptide composed solely of the helical rod domain of desmin. These data imply that the lamin B-binding site on desmin resides within the 21 residues following its helical rod domain, whereas the ankyrin-associating region is localized within its N-terminal head domain, exactly as in the case of vimentin.

Animals↗
PubMed1987

Tubulin-tyrosine ligase has a binding site on beta-tubulin: a two-domain structure of the enzyme.

Tubulin-tyrosine ligase and alpha beta-tubulin form a tight complex which is conveniently monitored by glycerol gradient centrifugation. Using two distinct ligase monoclonal antibodies, several subunit-specific tubulin monoclonal antibodies, and chemical cross-linking, a ligase-binding site was identified on beta-tubulin. This site is retained when the carboxy-terminal domains of both tubulin subunits are removed by subtilisin treatment. The ligase-tubulin complex is also formed when ligase is added to alpha beta-tubulin carrying the monoclonal antibody YL 1/2 which binds only to the carboxyl end of tyrosinated alpha-tubulin. The beta-tubulin-binding site described here explains the extreme substrate specificity of ligase, which does not act on other cellular proteins or carboxy-terminal peptides derived from detyrosinated alpha-tubulin. Differential accessibility of this site in tubulin and in microtubules seems to explain why ligase acts preferentially on unpolymerized tubulin. Ligase exposed to V8-protease is converted to a nicked derivative. This is devoid of enzymatic activity but still forms the complex with tubulin. Gel electrophoresis documents both 30- and a 14-kD domains, each which is immunologically and biochemically distinct and seems to cover the entire molecule. The two domains interact tightly under physiological conditions. The 30-kD domain carries the binding sites for beta-tubulin and ATP. The 14-kD domain can possibly form an additional part of the catalytic site as it harbors the epitope for the monoclonal antibody ID3 which inhibits enzymatic activity but not the formation of the ligase-tubulin complex.

Animals↗
PubMed1987

Actin typing of rhabdomyosarcomas shows the presence of the fetal and adult forms of sarcomeric muscle actin.

We analyzed actin expression in two human rhabdomyosarcomas as well as in three rhabdomyosarcomas induced in rats by the injection of nickel sulfide. All five tumors exhibited appreciable amounts of the sarcomeric alpha-actin types, in line with their myogenic differentiation. The level of these actins was particularly high in the rat tumors, which according to morphological criteria, all showed a higher degree of differentiation than the human tumors. Interestingly, in both human tumors and in two of the three rat tumors, the level of the cardiac alpha-actin type was significantly higher than that of adult skeletal muscle alpha-actin. Taken together with the results of recent reports indicating that the cardiac alpha-actin type is a marker of embryonic and fetal skeletal muscle, our findings indicate that rhabdomyosarcomas express the embryonic sarcomeric actin isoform.

Actins↗
PubMed1987

Turnover of the carboxy-terminal tyrosine of alpha-tubulin and means of reaching elevated levels of detyrosination in living cells.

Monoclonal antibodies specific for either the tyrosinated (Tyr) or the detyrosinated (Glu) form of alpha-tubulin were elicited with synthetic peptides spanning the carboxy-terminal sequences of the two forms. While almost all microtubules (MTs) are usually of the Tyr-tubulin type (Tyr-rich MTs) some MTs containing noticeable amounts of Glu-tubulin (Glu-rich MTs) were found in many but not all cell lines studied. Glu-rich MTs seemed absent from proliferating CHO and N115 neuroblastoma cells. When differentiation of these cells was initiated by the addition of forskolin for CHO, or by serum deprivation for N115, elevated levels of microtubular Glu-tubulin were observed. In differentiated N115 cells Glu-tubulin was restricted to MT of elongated cell processes and was not found in growth cones and many MT of the cell body. Elevated levels of Glu-tubulin were also characteristic of other differentiated cell types, including neurones and myotubes but were not found in glial cells, astrocytes and fibroblasts in the same primary cultures. Additional experiments suggested that the restricted distribution of Glu-tubulin is the result of MT subsets with different stabilities. Results with mitotic drugs indicated that detyrosination occurs on MTs rather than on soluble tubulin and that stabilization of MTs usually favours the detyrosination process. Evidence for a functional alpha-tubulin cycle involving an inherent carboxypeptidase and a recharging ligase was apparent in 3T3 cells from the preponderance of Glu-rich MTs induced by taxol treatment or the micro-injection of certain antibodies either protecting the detyrosinated form (Glu-tubulin antibodies) or inhibiting retyrosination (ligase antibodies). As the same treatment of CHO cells resulted in comparable arrays of Glu-rich MTs only when forskolin was also present, different cell types may differ in the level of active carboxypeptidase. The results are discussed in terms of possible functions of the tyrosination/detyrosination cycle of alpha-tubulin. While most results can be explained on the basis of 'older' and, consequently, more detyrosinated MTs, others raise the possibility that cyclic-AMP-dependent events and certain environmental influences known to induce either a morphological transformation or a differentiation event may influence the carboxypeptidase inherent in the alpha-tubulin cycle.

Animals↗
PubMed1987

Keratin filament disruption in interphase and mitotic cells--how is it induced?

We have studied the lability of keratin intermediate filaments in epithelial cell lines to try to understand the molecular mechanism that cause the ultrastructural transition from 10 nm filaments to the ball-like aggregates containing 2 to 3 nm filaments. Our results suggest that different growth conditions used in different laboratories may explain some but not all of the discrepancies in the literature on mitotic keratin filament disruption. Such disruption is not only cell type, but also subclone dependent and can be manipulated in one instance by altering the NaHCO3 concentration of the growth medium. An apparently similar filament to aggregate transition can be induced in interphase cells of some epithelial cell lines by incubation in a cold hypotonic buffer, or when cells are pretreated with phorbol ester and then incubated in cold physiological saline. A putative dialyzable and heat-stable factor present in medium conditioned by the growth of particular epithelial cell types may be required for disruption. Keratin polypeptide phosphorylation may play a role in filament labilization.

Animals↗