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M Osborn

Publications and source records attributed to M Osborn.

At least 19 recordsLinked to original sources
PubMed1992

Neurofilament epitopes in thymoma and antiaxonal autoantibodies in myasthenia gravis.

Expression by neoplastic thymic epithelial cells of acetylcholine-receptor (AChR) epitopes is associated with the presence of AChR autoantibodies and the development of myasthenia gravis. We studied thymic tumours from patients with and without myasthenia gravis for the expression of neurofilament epitopes by immunohistochemistry with four monoclonal antibodies. There was very little antibody binding in control samples (healthy thymus, or thymitis) or in medullary and mixed thymomas, but neurofilament epitopes were strongly expressed in all cortical thymomas and thymic carcinomas. In addition, the frequency of serum autoantibodies against axons was significantly higher among myasthenic patients with thymic epithelial tumours than among age-matched controls (7/10 vs 3/50; p less than 0.01).

Adolescent↗
PubMed1992

A striational muscle antigen and myasthenia gravis-associated thymomas share an acetylcholine-receptor epitope.

The coincidence of autoantibodies against the acetylcholine receptor (AChR) and muscle striational antigens (SA) is a characteristic finding in thymoma-associated myasthenia gravis (MG), but their origins are still unresolved. Some common muscle antigens that were shown to be targets of anti-SA autoantibodies in thymoma-associated MG have also been detected in normal or neoplastic thymic epithelial cells, suggesting that the release of (eventually altered) antigens from the thymic tumors could elicit SA autoimmunity. In contrast to this model, we report here that titin, which is a recently reported target of SA autoimmunity, is not expressed in thymomas. In addition, we show that skeletal muscle type-II fibers exhibit a striational immunoreactivity with monoclonal antibody mAb155, which was previously identified to label a very immunogenic cytoplasmic epitope of the AChR and neoplastic epithelial cells of MG-associated thymomas. We conclude from these findings that titin autoimmunity in thymoma-associated MG is either due to a molecular mimicry mechanism involving tumor antigens (other than titin) or is a secondary phenomenon following release of titin from muscle. Based on the common immunoreactivity of the AChR, a striational antigen and thymoma, we suggest as the pathogenetic mechanism of thymoma-associated MGa "circulus vitiosus" in which SA autoimmunity could help maintain the AChR autoimmunity that is primarily elicited by the thymomas.

Adult↗
PubMed1992

Ability to organize microtubules in taxol-treated mitotic PtK2 cells goes with the SPN antigen and not with the centrosome.

The SPN antigen plays an essential role in mitosis, since microinjection of antibodies causes mitotic arrest. Here we show, by examination of the relative locations of SPN antigen, the centrosomal 5051 antigen and tubulin in normal mitotic, and in taxol-treated mitotic cells, that the SPN antigen is involved in organizing the microtubules of the spindle. The 210 kDa protein defined as SPN antigen relocates from the nuclear matrix to the centrosome at prophase, remains associated with the poles at metaphase and anaphase, and dissociates from the centrosomes in telophase. In taxol-treated mitotic cells, SPN staining shows a striking redistribution while 5051 antigen remains associated with centrosomes. SPN antigen is seen at the plasma membrane end of the rearranged microtubules. SPN antigen is always at the center of the multiple microtubule asters (5 to 20 per cell) induced by taxol, whereas 5051 again remains associated with the centrosomal complex (1 to 2 foci per cell). Microtubule nucleation is associated with the SPN antigen rather than with the 5051 antigen. Microinjection of SPN-3 antibody into taxol-treated mitotic PtK2 cells causes disruption of the asters as judged by tubulin staining of the same cells. Finally, SPN antigen extracted in soluble form from synchronized mitotic HeLa cells binds to, and sediments with, pig brain microtubules stabilized by taxol. This association of SPN antigen with microtubules is partially dissociated by 0.5 M NaCl but not by 5 mM ATP. Thus SPN antigen binds to microtubules in vitro and seems to act as a microtubular minus-end organizer in mitotic cells in vivo.

Alkaloids↗
PubMed1992

The tight association of the tyrosine kinase substrate annexin II with the submembranous cytoskeleton depends on intact p11- and Ca(2+)-binding sites.

Annexin II, a member of the annexin family of Ca(2+)- and lipid-binding proteins, is a major substrate of the pp60src kinase. It is unique within the annexin protein family, since it can form a tight heterotetrameric complex with the cellular protein ligand p11, a member of the S100 protein family. Within the cell, the annexin II2p11(2) complex is localized at the cytoplasmic surface of the plasma membrane in the submembranous cytoskeleton. This intracellular localization is thought to be the consequence of a typical annexin II property observed in vitro, its Ca(2+)-dependent binding to phospholipids and cytoskeletal elements (F-actin, non-erythroid spectrin). We employed site-directed mutagenesis to create mutant annexin II molecules with defects either in the p11-binding site or in the Ca(2+)-binding sites present in repeats 2, 3 and 4. The mutated annexin II derivatives were expressed in HeLa and RMCD cells by transfection of the appropriate DNA constructs in order to analyze the importance of p11- and Ca(2+)-binding for the intracellular localization of annexin II. Immunofluorescence microscopy with a monoclonal antibody that specifically detected the transfected annexin II derivatives indicated that the Ca(2+)-dependent incorporation of annexin II into the submembranous network depended on its ability to form the annexin II/p11 complex and on the presence of intact Ca(2+)-binding sites. Neither monomeric annexin II lacking an intact p11-binding site, nor the annexin II mutant with defects in the Ca(2+)-binding sites in repeats 2, 3 and 4 were associated with the Triton X-100-resistant network of the submembranous cytoskeleton.

Amino Acid Sequence↗
PubMed1992

Cathepsin D in invasive ductal NOS breast carcinoma as defined by immunohistochemistry. No correlation with survival at 5 years.

Cathepsin D expression was assessed by immunohistochemistry in 59 node-negative and 77 node-positive infiltrative ductal not otherwise specified (NOS) breast carcinomas and compared with overall survival at 90 months. Cancer cells in 60% (81/136) of the tumors expressed cathepsin D. In the stroma of 33% (18 of 55) cathepsin D negative tumors, numerous strongly cathepsin D positive, benign macrophage-like cells were found. Multivariate analysis showed no significant correlation of cathepsin D expression and overall survival for all patients for node-negative and node-positive patients and for patients with vimentin-positive and -negative tumors. However, in node-negative but not in node-positive patients, a trend for better survival for patients with cathepsin-positive vimentin-negative tumors and worse survival for those with cathepsin-positive vimentin-positive tumors was noted. Due to the low number of patients in these subgroups, neither trend reached significance. Cathepsin D expression was independent of patient age, size, and histologic grade of tumor, and vimentin expression. However, in the node-positive group, negative correlation of cathepsin D and vimentin expression was found. We suggest that prognostic significance of cathepsin D in infiltrative ductal NOS breast carcinomas may be associated with the pathway of its synthesis rather than with its mere presence in tumor cells.

Breast Neoplasms↗
PubMed1992

A shared epitope in the acetylcholine receptor-alpha subunit and fast troponin I of skeletal muscle. Is it important for myasthenia gravis?

The monoclonal antibody MAb 155, isolated by Tzartos et al, recognizes the alpha subunit of acetylcholine receptor (AChR) and stains type II skeletal muscle fibers but does not decorate heart muscle. In addition it reacts with most myasthenia gravis-associated thymomas. The authors show by immunoblotting techniques that the myofibrillar antigen is a 23 kd protein and by partial protein sequence data identify it as fast troponin I. Fast troponin I from various species contains the sequence EEKSGMEGRK close to the C-terminal end at positions 165 to 174. The first lysine (K) is crucial for MAb 155 reactivity since its substitution by methionine and leucine in slow troponin I and cardiac troponin I, respectively, abolishes MAb 155 reactivity. The epitope identified on troponin I is homologous in sequence with the MAb 155 epitope on the AChR alpha subunit established by direct peptide binding as KSAIEGIK (positions 373-380). The authors consider whether fortuitously shared epitopes can be responsible for the high level of autoantibodies to AChR and to muscle proteins seen in many MG patients.

Amino Acid Sequence↗
PubMed1992

Microinjection of IFA antibody induces intermediate filament aggregates in epithelial cell lines but perinuclear coils in fibroblast-like lines.

The murine monoclonal IFA antibody recognizes a conserved sequence present in almost all intermediate filament (IF) proteins. When IFA antibody was injected into 13 different primary or established cell lines, striking differences were detected between epithelial and fibroblastic cell lines. In epithelial cells keratin IFs were broken down within 4 h into numerous spheroid aggregates scattered throughout the cytoplasm. Keratin aggregates were first detected in the cytoplasmic periphery. In contrast, in fibroblastic cells, injection of IFA antibody led to the formation of perinuclear coils of vimentin. IFA antibody at a concentration of greater than 1 mg/ml had to be injected to initiate these transitions. When HeLa cells, which contain separate networks of vimentin and keratin filaments, were injected with IFA antibody, vimentin did not form perinuclear coils but was instead found together with keratin in aggregates. Electron micrographs of HeLa cells injected with IFA antibody showed that the aggregates have diameters between 0.5 and 2.6 microns and resembled the keratin aggregates observed in certain mitotic epithelial cells. Although the ultrastructural studies support an association of some aggregates with desmosomes, aggregates were, however, also induced by injection of IFA antibody into human keratinocytes in low calcium medium under conditions where desmosomes were not present.

3T3 Cells↗
PubMed1991

A 210 kDa nuclear matrix protein is a functional part of the mitotic spindle; a microinjection study using SPN monoclonal antibodies.

Six monoclonal antibodies identify a 210 kDa polypeptide which shows a cell cycle specific redistribution from the nucleus to the mitotic spindle. In interphase cells this polypeptide was localized in the nucleus and behaved during differential cell extraction as a component of the nuclear matrix. It accumulated in the centrosome region at prophase, in the pole regions of the mitotic spindle at metaphase and in crescents at the poles in anaphase, and reassociated with the nuclei as they reformed in telophase. Due to its staining pattern we call the protein the Spindle Pole-Nucleus (SPN) antigen. The localization of SPN antigen during mitosis was dependent on the integrity of the spindle since treatment of cells with nocodazole resulted in the dispersal of SPN antigen into many small foci which acted as microtubule organizing centres when the drug was removed. The SPN antigen was present in nuclei and mitotic spindles of all human and mammalian cell lines and tissues so far tested. When microinjected into the cytoplasm or nuclei of HeLa cells, one antibody caused a block in mitosis. Total cell number remained constant or decreased slightly after 24 h. At this time, about half the cells were arrested in a prometaphase-like state and revealed aberrant spindles. Many other cells were multinucleate. These results show that the SPN antigen is a protein associated with mitotic spindle microtubules which has to function correctly for the cell to complete mitosis.

Antibodies, Monoclonal↗
PubMed1991

Randomised controlled trial of day and in-patient psychiatric treatment. 2: Comparison of two hospitals.

Acutely ill patients presenting for admission in two district psychiatric services were randomly allocated to day-hospital or in-patient care. In both services a quarter of all admissions could not be allocated because they were too ill (half of these were compulsory admissions); these patients were predominantly manic and schizophrenic patients with pronounced psychotic symptoms and disturbed behaviour. In one service 80% (41/51) of patients randomly allocated to day-hospital treatment were successfully engaged in treatment compared with 54% (19/35) in the other service. This difference arose because only patients with mildly disturbed behaviour could be treated at the second day hospital. For patients who were successfully allocated, the outcome of treatment was similar in terms of psychiatric symptoms and social functioning. The results of a treatment trial for acutely ill patients in one district service cannot be generalised to other district services without due attention to the factors, such as staffing levels, which determine the degree of disturbed behaviour that can be tolerated in the day hospital.

Acute Disease↗
PubMed1991

Immunocytochemistry in fine needle aspirates of small cell-, round-, blue-cell malignant tumors of childhood (neuroblastoma, nephroblastoma, lymphoma, Ewing's sarcoma, rhabdomyosarcoma).

Immunocytochemistry with the use of monoclonal antibodies to vimentin, keratin, desmin, neurofilaments and leukocyte common antigen (LCA) was applied to 53 fine needle aspirates of small cell-, round-, blue-cell malignant tumors of childhood (neuroblastomas, nephroblastomas, non-Hodgkin's lymphomas, Ewing's sarcomas and rhabdomyosarcomas). The results revealed the following immunophenotypes: neuroblastomas were positive for neurofilaments. Nephroblastomas contained vimentin (in blastema cells), keratin (in epithelial and blastema cells) Non-Hodgkin's lymphomas were vimentin and LCA positive, keratin negative. Ewing's sarcomas displayed multidirectional differentiation. Rhabdomyosarcomas were desmin and vimentin positive. It is concluded that immunocytochemistry in fine needle aspirates should be used as an objective evidence to support morphologic differential diagnosis of small cell-, round-, blue cell malignant tumors of childhood.

Biopsy, Needle↗
PubMed1991

Cytokeratin expression and vimentin content in large cell anaplastic lymphomas and other non-Hodgkin's lymphomas.

The immunophenotypes of 74 malignant lymphomas (9 Hodgkin's disease, 19 low-grade B-cell, 20 high-grade B-cell, 8 T-cell, and 18 large cell anaplastic lymphomas [LCAL]) have been characterized with antibodies against leucocyte differentiation antigens, keratin, and vimentin. All the non-LCAL were CD45 positive and keratin negative. The LCALs had a more varied immunophenotype, with CD45 present only in 11 of 18 cases and keratin present in 5 of 18 of these rare lymphomas. The lymphoid origin of these latter cases was proven by gene rearrangement studies. All LCALs were CD30+, and, where tested, vimentin positive. Of four different vimentin monoclonal antibodies tested, V9 and MVI stained the highest number of lymphomas. Positive staining of tumor cells was seen in 61 of 71 cases. Vimentin-negative cases included Burkitt's as well as some follicular lymphomas.

DNA↗
PubMed1991

Unexpected immunoreactivities of intermediate filament antibodies in human brain and brain tumors.

Immunoreactivities of 35 different monoclonal antibodies (MAbs) that detect intermediate filaments were studied systematically on serial cryostat sections of 14 well-defined human gliomas (five astrocytomas, three oligodendrogliomas, six glioblastomas) and on normal brain. Glial fibrillary acidic protein (GFAP), vimentin, desmin, neurofilaments, and broad-specificity keratin MAbs, as well as MAbs that recognize several or only single keratin polypeptides, were used. Unexpected reactivities were surprisingly frequent. As these may lead to diagnostic confusion and misinterpretation on this material, the authors investigated these phenomena more thoroughly. Four major sources of artifactual staining were found: 1) positive staining attributable to the rabbit gamma G immunoglobulins used in the alkaline phosphatase anti-alkaline phosphatase technique; 2) certain desmin and keratin MAbs cross-reacted with astrocytic glia and with other brain-specific epitopes; 3) technical difficulties; 4) some MAbs directed against neurofilaments and keratins showed unexpected reactivities only on individual anaplastic gliomas. The implications of these findings for intermediate filament typing of neuropathologic material are discussed.

Antibodies, Monoclonal↗
PubMed1991

Immunocytochemical criteria in the differential diagnosis of malignant melanoma versus carcinoma, lymphoma and sarcoma in fine needle aspirates.

Monoclonal antibodies to keratin, vimentin, leukocyte common antigen (LCA) and S-100 protein have been used in fine needle aspirates of 35 metastatic malignant melanomas, 136 carcinomas, 35 sarcomas and 82 non-Hodgkin's lymphomas in search for immunocytochemical criteria useful in differential diagnosis of melanoma versus carcinoma, non-Hodgkin's lymphoma and sarcoma. All melanomas expressed vimentin and did not express keratin. Six of 14 melanomas contained S-100 protein. All carcinomas were keratin positive. Some were also vimentin positive. All sarcomas expressed vimentin. Synovial sarcomas were also keratin positive. All NHLs were vimentin positive, keratin negative. All NHLs except one expressed also LCA. It is concluded that keratin, vimentin and LCA are useful markers in differential diagnosis of malignant melanoma versus carcinoma and non-Hodgkin's lymphoma in fine needle aspirates when used together with morphologic and clinical data. However, in differential diagnosis of malignant melanoma and sarcoma these markers are of little use.

Biopsy, Needle↗
PubMed1991

Dendritic accessory cells derived from rat bone marrow precursors under chemically defined conditions in vitro belong to the myeloid lineage.

Serum-free conditions have been developed to differentiate dendritic cells from a non-adherent fraction of rat bone marrow precursors by action of the multipotential and macrophage colony-stimulating factors further supplemented with linoleic acid, vitamin E, and vitamin D3. Accessory activity was demonstrated by the high potency of the dendritic cells to stimulate autologous T cell proliferation, whereas such cells were negative for Fc receptor-dependent phagocytosis, a characteristic macrophage feature. While the dendritic cells were weakly positive for alpha-naphtylbutyrate esterase, they strongly expressed RT.1 class II antigens. Apparently, these cells represent a more differentiated phenotype since they expressed the nuclear A/C lamins. By addition of serum to the cultures, the dendritic cells developed into macrophages, which were also lamin A/C-positive as well as strongly positive for alpha-naphtylbutyrate esterase. Thus, these dendritic cells belong to the myeloid lineage, and it appears as if serum factor(s) control differentiation at a mature level. Suitable conditions could also be established for large-scale cultures of dendritic cells, which would be useful for applications requiring higher numbers of cells.

Animals↗
PubMed1990

Randomised controlled trial of day patient versus inpatient psychiatric treatment.

OBJECTIVE: To assess the proportion of acutely ill psychiatric patients who can be treated in a day hospital and compare the outcome of day patient and inpatient treatment. DESIGN: Prospective randomised controlled trial of day patient versus inpatient treatment after exclusion of patients precluded by severity of illness or other factors from being treated as day patients. All three groups assessed at three and 12 months. SETTING: Teaching hospital serving small socially deprived inner city area. Day hospital designed to take acute admissions because of few beds. PATIENTS: 175 Patients were considered, of whom 73 could not be allocated. Of the remaining 102 patients, 51 were allocated to each treatment setting but only 89 became established in treatment--namely, 41 day patients and 48 inpatients. 73 Of these 89 patients were reassessed at three months and 70 at one year. INTERVENTIONS: Standard day patient and inpatient treatment. MAIN OUTCOME MEASURES: Discharge from hospital and return to previous level of social functioning; reduction of psychiatric symptoms, abnormal behaviour, and burden on relatives. RESULTS: 33 Of 48 inpatients were discharged at three months compared with 17 of 41 day patients. But at one year 9 of 48 inpatients and three of 41 day patients were in hospital. 18 Of 35 day patients and 16 of 39 inpatients were at their previous level of social functioning at one year. The only significant difference at three months was a greater improvement in social role performance in the inpatients. At one year there was no significant difference between day patients and inpatients in present state examination summary scores and social role performance, burden, or behaviour. CONCLUSIONS: Roughly 40% of all acutely ill patients presenting for admission to a psychiatric unit may be treated satisfactorily in a well staffed day hospital. The outcome of treatment is similar to that of inpatient care but might possibly reduce readmissions. The hospital costs seem to be similar but further research is required to assess the costs in terms of extra demands on relatives, general practitioners, and other community resources.

Acute Disease↗
PubMed1990

Expression of villin in the mouse oviduct and the seminiferous ducts.

Villin, a 95-kD cytoskeletal protein selectively expressed in the microvilli of some absorptive cells was localized immunohistochemically in the oviduct and the seminiferous excretory ducts of the mouse. Villin was found in the proximal part of the oviduct, comprising the preampulla, ampulla, and part of the isthmus. Distal to the isthmus the oviductal cells lining the junctura and the intrauterine colliculus tubaris were devoid of villin. No villin could be detected in the uterine cells. Ductuli efferentes, connecting the rete testis with the epididymis were the only portion of the male seminiferous ductal system expressing villin. The cells lining the epididymis and the vas deferens were devoid of villin. These data show that villin is selectively expressed in male and female reproductive systems and that it is limited to anatomically defined proximal portions of the reproductive ducts.

Animals↗
PubMed1990

Induction of nuclear lamins A/C in macrophages in in vitro cultures of rat bone marrow precursor cells and human blood monocytes, and in macrophages elicited in vivo by thioglycollate stimulation.

Hemopoietic cells from blood and bone marrow of mammals usually do not express lamins A/C but only lamin B, and this feature distinguishes these cells from the vast majority of somatic cells of the adult animal, which reveal lamins A/C as well as lamin B. Here we have cultivated rat bone marrow precursor cells and human monocytes isolated from peripheral blood in tissue culture supplemented with certain growth factors. These conditions allow bone marrow precursor cells and monocytes to differentiate almost quantitatively into accessory cells and/or mature macrophages. The different cell types in the cultures can be identified both morphologically and by other assays. Antibodies specific for mouse A/C lamins, human A/C lamins, or B lamins have been used to define the lamin complement as a function of time in culture and of cell type. A dramatic increase in lamin A/C-positive cells was observed in the first 3 days of culture with both accessory cells and macrophages expressing lamins A/C as soon as such cell types could be identified. Parallel in vivo experiments showed that treatment with thioglycollate caused the percentage of lamin A/C-positive peritoneal macrophages to increase from 5 to 80% between Days 0 and 6.

Animals↗