Search PubMed⌕ Search

Biomedical subjects

B H Toh

Publications and source records attributed to B H Toh.

At least 145 records · Page 8Linked to original sources
PubMed1983

Flow microfluorimetric analysis of autoantibody reactions with parietal cell surface membranes in pernicious anaemia.

Using flow microfluorimetry (FMF), 60 sera from patients with pernicious anaemia (PA) were examined for immunoreactivity with the surface membranes of viable canine parietal cells. FMF analyses showed that the percentage of parietal cells giving a surface staining reaction with a fluorescence intensity greater than 50 arbitrary units was 44.5 +/- 17.5% for sera from 60 patients with PA compared to 13.7 +/- 2.7% for sera from 14 patients with chronic active hepatitis, 10.7 +/- 6.7% for sera from 10 patients with systemic lupus erythematosus and 16.5 +/- 4.4% for sera from 50 healthy persons. Surface staining detected by FMF was restricted to parietal cells and abolished by absorption with parietal cell enriched preparations but not by absorption with dog or rat hepatocytes, dog or rat kidney cells, human fibroblasts, human AB red blood cells or dog gastric microsomes. The intensity of the parietal cell surface staining reactions correlated with the presence of antibody reactions with parietal cell surfaces previously demonstrated by immunofluorescence microscopy but did not correlate with the presence of microsomal or intrinsic factor autoantibodies. The results provide further support for the presence of a parietal cell surface reactive autoantibody distinct from the conventional parietal cell microsomal autoantibody.

Anemia, Pernicious↗
PubMed1982

Segregation of autoantibody to cytoskeletal filaments, actin and intermediate filaments with two types of chronic active hepatitis.

Regional differences in serological features of chronic active hepatitis (CAH) were assessed from study of unselected patients with CAH, 53 from Zagreb, Yugoslavia and 53 from Melbourne, Australia. A group of 29 patients from Zagreb with chronic persistent hepatitis (CPH) was also included. The serological marker studied was immunofluorescence reactivity to cytoskeletal components, actin cables (AC) and intermediate filaments (IF), these being mostly responsible for the smooth muscle antibody reactivity which occurs in CAH. The Zagreb cases of CAH differed from the Melbourne cases by having a significantly lower frequency of anti-AC (8% vs 55%) and a significantly higher frequency of anti-IF (34% vs 15%), and correspondingly had a higher frequency of markers of hepatitis B virus (HBV) infection (HBsAg, 53% vs 8% and anti-HBc, 72% vs 34%), and a differing HLA profile, with HLA BW35 higher (38% vs 14%) and B8 lower (18% vs 56%). This study illustrates the differences among populations in expression of CAH, in that HBsAg is held to specify the HBV-associated type, and antibody to actin is held to specify the autoimmune type. These differences would be determined in part by environmental influences, notably HBV, and genetic influences, notably HLA, and are reflected by the differing patterns of immunofluorescence reactivity with the cellular cytoskeleton.

Actins↗
PubMed1982

Dihydrotestosterone and estradiol deplete corticosensitive thymocytes lacking in receptors for these hormones.

The sex steroids dihydrotestosterone (DHT) and estradiol (E2), were found to deplete the same cortical population of thymocytes as the glucocorticoid dexamethasone (DM) in intact and in adrenalectomized, castrated mice. Although receptors for DM were demonstrated in this cortical population, none were found for E2 or DHT. We suggest that the sex steroids bind to other thymic elements, possibly thymic reticular epithelial cells, which may in turn act secondarily on cortical thymocytes, or their precursors within the thymus.

Animals↗
PubMed1982

Autoantibodies to fibroblasts in scleroderma.

Sera from 33 patients with scleroderma were examined for immunofluorescent reactivity with viable or acetone-fixed fibroblasts. All 33 sera reacted with the cell surface membranes of viable fibroblasts. 23 of 33 sera (70%) also reacted with nuclei of acetone-fixed fibroblasts. The commonest nuclear staining pattern was homogeneous (46%) followed by nucleolar (36%) and speckled (23%). 70% showed more than 1 staining pattern in the same serum. Antibody titres of homogeneous and nucleolar staining patterns (1:8 to 1:1024) were generally higher than those of the speckled pattern (1:8 to 1:256). No change in pattern or titre was noted in sera from 4 patients over a 10-12 month period. Antibody in sera with homogeneous or nucleolar staining patterns belonged to one or more of the 3 major antibody classes, IgG, IgM or IgA while antibody in sera with a speckled nuclear pattern belonged to the IgM class only. No correlation was found between the pattern of anti-nuclear reactivity and visceral involvement.

Adult↗
PubMed1981

Cerebral lupus erythematosus responding to plasmaphaeresis.

A 44-year-old nurse with a 12-year history of systemic lupus erythematosus developed a schizophrenia-like psychosis due to cerebral lupus. Prednisolone in doses up to 200 mg daily was ineffective. Levels of immune complexes by the Raji cell assay were greatly increased in serum and cerebrospinal fluid. Plasma exchange was performed on 4 occasions over 4 days. Three days later, there was a marked and sustained improvement in the mental state, the psychosis resolved and tests of psychological function and electroencephalographic abnormalities improved. There was a corresponding decrease in levels of immune complexes and in titres of anti-neuronal antibody. Five months later, several serological indices had risen to pre-plasmaphaeresis levels except for the level of immune complexes. The patient remained in clinical remission. This case provides further evidence that high levels of circulating immune complexes may be a determinant of cerebral lupus and that plasmaphaeresis may be of lasting benefit in this disease.

Adult↗
PubMed1981

IgM autoantibody to intermediate filaments in infectious mononucleosis.

Sera from 17 patients with infectious mononucleosis reacted with fine cytoplasmic fibrils in monolayer cultures of fibroblasts. In cells pre-treated with vinblastine, the sera reacted with peri- or juxta-nuclear coils of filaments. These staining patterns were similar to those obtained by anti-intermediate filament autoantibody but different from the "actin-cables" stained by anti-actin autoantibody and from the "tubulin paracrystals" stained by anti-microtubule autoantibody. The autoantibodies belonged to the IgM class and ranged in titre from 1 : 16 to 1:512 (mean 1:64). A change in antibody titre was noted in sequential acute and convalescent sera. The results show that IgM autoantibodies to intermediate filaments occur frequently in sera from patients with infectious mononucleosis.

Actins↗
PubMed1980

Binding sites of fluorescent derivatives of insulin in nuclei, rough endoplasmic reticulum, and mitochondria.

Intracellular insulin-binding sites were directly traced in fixed monolayer cultures of a variety of cell types with the use of two fluorescent derivatives of insulin, viz. fluorescein isothiocyanate (FITC)-labelled and tetramethyl rhodamine isothiocyanate (TMRITC)-labelled insulin. Both derivatives retained the property of stimulating DNA synthesis in fibroblasts. Insulin-binding sites were found in the nuclear envelope, nucleoplasm, nucleoli, and in mitochondria and rough endoplasmic reticulum. The identity of these structures was established by concomitant studies on the same cell by means of phase contrast optics and immunocytochemical tracing with specific antibodies to nuclei, mitochondria, or ribosomes. Binding of insulin to the nuclear and cytoplasmic structures was rapid, reversible and saturable, temperature and pH-dependent, and inhibited by an excess of native, but not other, hormones. The staining reactions were sensitive to treatment by the nonionic detergents, NP-40 and TX-100, and to trypsin and pronase, but not to DNase and RNase, suggesting that the binding sites are protein in nature.

Animals↗
PubMed1980

Association of mitochondria with intermediate filaments and of polyribosomes with cytoplasmic actin.

Anti-mitochondrial autoantibody and fluorescent derivatives of insulin stain phase-dense mitochondria in acetone fixed monolayers of fibroblasts. Double fluorochrome studies show mitochondria in close topographic association with intermediate filaments. In cells treated with vinblastine or colchicine, mitochondria are relocated in sites closely associated with coils of perinuclear intermediate filaments. In contrast, autoantibody to polyribosomes stains granules aligned in the long axis of well spread embryonic cells, in the direction of actin-containing fibrils, an arrangement that is lost in cells pretreated with the actin filament disrupting drug cytochalasin B. In more mature fibroblasts, antiribosomal antibody reacts with phase-dense rough endoplasmic reticulum and this staining pattern is not affected by cytochalasin B. The observations suggest that mitochondria are associated with intermediate filaments and that free polyribosomes, but not polyribosomes attached to rough endoplasmic reticulum, are associated with cytoplasmic actin.

Actins↗
PubMed1980

Immunoperoxidase EM localisation of cytoplasmic actin in cultured fibroblasts.

Human smooth muscle autoantibody (SMA) of defined anti-actin specificity was tested by the indirect immunoperoxidase staining method on frozen sections of tissues and on cultured rat lung fibroblasts. The serum stained tissue sections and cultured fibroblasts in a pattern identical with that obtained by indirect immunofluorescence. Ultrastructural studies carried out on the immunoperoxidase stained cells showed that the long parallel filaments spanning the long axis of cultured fibroblasts seen by light microscopy correspond with the thick bundles of microfilaments.

Actins↗
PubMed1980

Method for preparing cultures of central neurons: cytochemical and immunochemical studies.

We report a simplified method for culturing fetal central nervous system cells predominantly inducing neurons that grow, differentiate, and live in vitro for as long as 10 weeks. These central nervous system cells form a confluent cell culture in which about 80% of the cells are fully differentiated neurons producing interconnecting axons and dendrite processes and live upon a sparse underlying population of fibrillary and protoplasmic astrocytes, oligodendrocytes, and fibroblasts. Morphological and cytochemical characteristics of these cell types, based on immunofluorescent cell specific markers and silver staining of neurons, are presented.

Animals↗
PubMed1980

Co-capping of insulin, epidermal growth factor and concanavalin A surface receptors with each other and with cytoplasmic actin.

Concanavalin A (Con A), insulin and epidermal growth factor (EGF) surface membrane receptors on cultured bovine odontogenic epithelial cells, were demonstrated by immunofluorescent reactivity with fluorescein-isothiocyanate (FITC) conjugated Con A, FITC-insulin, or EGF and anti-EGF, traced with FITC goat anti-rabbit globulin. Con A, insulin and EGF receptors co-capped with each other and with cytoplasmic actin; the latter was demonstrated by anti-actin antibody (AAA) traced with fluorescein or rhodamine-labelled goat anti-human globulin. Capping of receptors was promoted by prior treatment of cells with cytochalasin B or colchicine, but inhibited by the presence of the drugs throughout the experimental procedure. Binding of a ligand to its receptor promoted capping of an unrelated ligand-bound receptor, a phenomenon that was inhibited by cytochalasin B or colchicine. These results suggest that surface receptors for insulin, EGF and Con A interact with each other and with cytoplasmic actin.

Actins↗
PubMed1980

Autoantibody to ribosomes and systemic lupus erythematosus.

Sera from a patient with systemic lupus erythematosus (SLE), tested by indirect immunofluorescence on frozen tissue sections, gave granular cytoplasmic staining of hepatocytes, gastric chief cells, exocrine cells of the pancreas and submandibular glands, and cerebellar Purkinje cells. In acetone-fixed monolayers of rat embryonic fibroblasts, 3T3 cells, mouse neuroblastoma cells, and cells from a human melanoma and colon carcinoma cell line, the sera stained perinuclear cytoplasmic granules which radiated out towards the cell periphery. More mature and differentiated fibroblasts from rat of human foetal lung showed staining of reticular cytoplasmic structures corresponding to phase-dense rough endoplasmic reticulum (RER). Nucleoli were prominently stained in all cultured cells. Serum absorption with ribosomes inhibited all antibody activity but absorption with RNA or with RNase-treated ribosomes resulted only in partial inhibition. Monolayers of RNase-treated fibroblasts gave weaker staining reactions compared to control untreated cultures. These observations suggest that the autoantibody is directed against ribosomal RNA and ribosomal protein present in cytoplasmic polyribosomes, in RER and in nucleoli.

Antibody Specificity↗
PubMed1979

Distribution of actin and myosin in muscle and non-muscle cells.

Specific anti-actin and anti-myosin antibodies were shown to react in single and double immunofluorescence sandwich tests with identical sites in non-muscle cells in frozen sections of tissues and in cultured cells. In tissues, both antibodies reacted with liver cell membranes, parts of renal glomeruli, brush borders and peritubular fibrils of renal tubules, brain synaptic junctions, and membranes of lymphoid cells in thymic medulla, lymph nodes and spleen. Both antibodies reacted strongly with long parallel cytoplasmic fibrils in cultured fibroblasts, and with disrupted fibrils in cytochalasin-B treated cells. In neuroblastoma cells both antibodies gave prominent staining of growth cones and microspikes. The observation that the distribution of myosin parallels that of actin in non-muscle cells argues strongly in favour of a functional interaction between the two molecules in the generation of contractile activity in non-muscle cells.

Actins↗