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At least 1,621 records · Page 90Linked to original sources
PubMed1994

Detection of rectal antibodies to HIV-1 by a sensitive chemiluminescent western blot immunodetection method.

Western blot with a time-dependent enhanced chemiluminescence immunodetection method (ECL-WB) was shown to be 100-fold more sensitive than standard commercial colorimetric Western blots (WB) for detecting serum IgG to human immunodeficiency virus type 1 (HIV-1). ECL-WB was then used to test rectal secretions from 15 HIV-1 infected subjects (HIV+) and 7 uninfected subjects (HIV-) to document local IgG, IgA, and secretory component-associated immunoglobulin (SC-Ig) to HIV-1 proteins. Fourteen of 15 HIV+ subjects had rectal IgA to at least 1 HIV-1 protein, most often to gp41 (80%) or p24 (60%) and 14 (93%) had IgG to gp160, gp120, or gp41. Of seven HIV- subjects, none had detectable bands to HIV-1 proteins. SC-Ig to HIV-1 proteins was detected in all five rectal samples tested. However, the antibody profiles differed from those of rectal IgA, suggesting more than one source of rectal IgA to HIV. ECL-WB requires individual optimization and interpretation for each specimen as well as expensive reagents and is, therefore, not currently applicable to screening assays. However, the method offers promise as a sensitive method to characterize low-level immune responses (IgG, IgA, and SC-Ig) to HIV-1 proteins at local sites such as rectal mucosae.

Blotting, Western↗
PubMed2006

Human Sec31B: a family of new mammalian orthologues of yeast Sec31p that associate with the COPII coat.

We have cloned human brain and testis Sec31B protein (also known as secretory pathway component Sec31B-1 or SEC31-like 2; GenBank accession number AF274863). Sec31B is an orthologue of Saccharomyces cerevisiae Sec31p, a component of the COPII vesicle coat that mediates vesicular traffic from the endoplasmic reticulum. Sec31B is widely expressed and enriched in cerebellum and testis. Its predicted sequence of 1180 residues (expected molecular mass 128,711 Da) shares 47.3% and 18.8% similarity to human Sec31A (also known as Sec31; GenBank accession number AF139184) and yeast Sec31p, respectively. The gene encoding Sec31B is located on chromosome 10q24 and contains 29 exons. PCR analysis of exon utilization reveals massive alternative mRNA splicing of Sec31B, with just 16 exons being constitutively utilized in all transcripts. The presence of a stop codon in exon 13 generates two families of Sec31B gene products (each displaying additional patterns of mRNA splicing): a group of full-length proteins (hereafter referred to as Sec31B-F) and also a group of truncated proteins (hereafter referred to as Sec31B-T), distinguished by their utilization of exon 13. Sec31B-F closely resembles Sec31p and Sec31A, with canonical WD repeats in an N-terminal domain that binds Sec13 and a proline-rich C-terminal region that presumably binds Sec23/24. The Sec31B-T group (molecular mass 52,983 Da) contains a preserved WD-repeat domain but lacks the C-terminal proline-rich region. When expressed as a fusion protein with eYFP in cultured cells, Sec31B-F associates with the endoplasmic reticulum and with vesicular-tubular clusters, displays restricted intracellular movement characteristic of COPII vesicle dynamics, co-distributes on organelles with Sec13, Sec31A and Sec23 (markers of the COPII coat), and concentrates with ts045-VSV-G-CFP (VSV-G) when examined early in the secretory pathway or after temperature or nocodazole inhibition. The role of the truncated form Sec31B-T appears to be distinct from that of Sec31B-F and remains unknown. We conclude that Sec31B-F contributes to the diversity of the mammalian COPII coat, and speculate that the Sec31 cage, like Sec24, might be built with isoforms tuned to specific types of cargo or to other specialized functions.

Alternative Splicing↗
PubMed1993

Adaptor self-aggregation, adaptor-receptor recognition and binding of alpha-adaptin subunits to the plasma membrane contribute to recruitment of adaptor (AP2) components of clathrin-coated pits.

Initiation of receptor-mediated endocytosis by nucleation of clathrin-coated pits involves binding of AP2 adaptor molecules to the plasma membrane. This process was reconstituted in vitro, using plasma membrane fragments, prepared by freeze-thaw lysis of cells, and stripped of their endogenous coat proteins, as targets for binding of purified adaptor molecules and their dissociated subunits. The dissociated alpha-adaptin subunit of AP2 bound to plasma membrane fragments, while the dissociated beta-adaptin subunit did not, suggesting that plasma membrane localization of AP2 adaptors is mediated by alpha-adaptin. Membrane binding of intact AP2 adaptor molecules was enhanced by adaptor self-aggregation, which can be modulated by physiological concentrations of inositol phosphates, and may therefore be sensitive to receptor signaling. Adaptor binding was partially inhibited by soluble peptides representing the cytoplasmic domains of the asialoglycoprotein receptor and the polymeric immunoglobulin receptor. These results indicate that direct binding of adaptors to the cytoplasmic domains of receptors contributes to coated pit nucleation but this appears to be a weak interaction, suggesting that an additional recognition signal could be required for high affinity adaptor binding.

Adaptor Protein Complex 2↗
PubMed2001

The effect of dexamethasone on respirator-dependent very-low-birth-weight infants is best predicted by chest X-ray.

BACKGROUND: Chronic lung disease (CLD) in premature infants shows a variable clinical course with different radiological manifestations. OBJECTIVE: To evaluate the correlation between parameters of trans-membrane permeability [albumin/secretory component (SC)] and oxidative stress [malondialdehyde (MDA)/SC] in tracheal aspirate fluid (TAF) and radiological findings with the effect of a 5-day course of dexamethasone (0.5 mg/kg per day). MATERIALS AND METHODS: Fifty ventilator-dependent premature infants with birth weights < 1,500 g (gestational ages 23-31 weeks) and radiological signs of early chronic lung disease (CLD) were treated with dexamethasone at day of life 5-27 (median 10 days) because of respiratory deterioration. TAF was collected serially. Chest X-rays taken before and 8-10 days after dexamethasone were scored for changes of opacification, consolidation and hyperinflation/emphysema, and classified into three groups. RESULTS: Twenty-four infants had a positive response to dexamethasone, defined as a reduction of the ventilation index FiO2 x mean airway pressure > 40% at day 5, compared to pretreatment values. About 80% of the responders showed homogeneous lung opacification on chest X-ray, reflecting leaky lung syndrome. In contrast, seven of eight infants with predominantly emphysema on radiology were non-responders; 80% of infants with a mixed radiological picture characterized by predominance of consolidations alternating with regions of emphysema were also non-responders. Ratios of albumin/SC and MDA/SC in TAF decreased significantly within 3 days after the onset of dexamethasone. However, MDA/SC was persistently higher in non-responders compared to responders. Opaque lungs were largely improved by dexamethasone, in contrast to streaky or patchy consolidations and emphysema. In a logistic regression model, radiographic classification was the most important factor influencing the response to dexamethasone with a positive predictive value of 86%, followed by albumin/SC ratio. CONCLUSIONS: The optimum timing of dexamethasone treatment may be determined by the stage of developing CLD and radiological findings rather than by the age of the premature infant.

Albumins↗
PubMed1984

Ultrastructural and immunohistochemical studies of bronchiolo-alveolar carcinoma.

A detailed ultrastructural study was made of seven cases of bronchiolo-alveolar carcinoma, and the findings were correlated with histochemical and immunohistochemical data. By electron microscopic examination all seven tumors displayed glandular differentiation, manifested by the presence of microvilli and intercellular junctions, with or without mucin production. Variable proportions of tumor cells retained ultrastructural characteristics of alveolar type II cells and Clara cells. In addition, some tumor cells revealed desmosomes and tonofilaments consistent with squamous differentiation. Immunohistochemical evaluation was carried out using a peroxidase-antiperoxidase technique and specific antibodies against surfactant high molecular weight glycoproteins, keratin proteins, IgA + secretory piece, carcinoembryonic antigen (CEA), human chorionic gonadotropin (HCG), and alpha-fetoprotein (AFP). Four tumors with type II cell-like differentiation stained with anti-surfactant glycoprotein sera. All seven tumors stained focally with anti-keratin and IgA + anti-secretory piece antibodies, and diffusely with CEA. These tumors failed to stain with antisera against HCG and AFP. It is concluded that bronciolo-alveolar carcinomas are primarily composed of cells with alveolar and bronchiolar cell differentiation. Adequate criteria were established for ultrastructural identification of tumor cells with differentiation to type II alveolar cell or Clara cell. Moreover, the findings of this study indicate that the surfactant glycoprotein marker, when present in a given tumor either diffusely or focally, is diagnostic of bronchiolo-alveolar carcinoma.

Adenocarcinoma↗
PubMed1992

Molecular cloning of a novel member of the immunoglobulin gene superfamily homologous to the polymeric immunoglobulin receptor.

The CMRF35 monoclonal antibody recognizes a cell membrane antigen present on the surface of monocytes, neutrophils, a proportion of peripheral blood T and B lymphocytes and lymphocytic cell lines. Initial studies with CMRF35 suggested an unusual pattern of serological reactivity which did not correspond to any of the known leukocyte differentiation antigen clusters. We describe here the cloning and sequencing of a cDNA encoding the CMRF35 antigen by means of expression in COS cells and immunoselection with the CMRF35 monoclonal antibody. The cDNA encodes a novel integral membrane glycoprotein of 224 amino acids that represents a new member of the immunoglobulin (Ig) gene superfamily. The molecule comprises (a) a single extracellular Ig variable domain remarkably similar to the Fc receptor for polymeric IgA and IgM, (b) a membrane-proximal domain containing a high proportion of proline, serine and threonine residues that was predicted to be heavily O-glycosylated, (c) an unusual transmembrane anchor that contained a glutamic acid and a proline residue and (d) a short cytoplasmic tail. Transcripts encoding the CMRF35 protein were detected in early monocytic cell lines, in peripheral blood T cells and in some B lymphoblastoid cell lines, confirming the results of immunocytological staining. However, the level of CMRF35 expression on peripheral blood T cells was shown to decrease in response to mitogenic stimulation. The likelihood that the CMRF35 antigen shares a common evolutionary ancestor with the poly Ig Fc receptor is discussed.

Amino Acid Sequence↗
PubMedDate not supplied

Immunoglobulin A antibody against hepatitis B core antigen of polymeric and monomeric forms, as well as of IgA1 and IgA2 subclasses, in acute and chronic infection with hepatitis B virus.

Solid-phase radioimmunoassays using monoclonal antibodies were used to assay antibody to hepatitis B core antigen of immunoglobulin A class in terms of polymeric and monomeric forms, as well as of IgA1 and IgA2 subclasses, in the serum of persons infected with hepatitis B virus. The level of secretory immunoglobulin A antibody was significantly higher in patients with acute hepatitis (mean +/- S.E., sample per normal ratio = 29.2 +/- 1.9) than that in asymptomatic carriers (2.1 +/- 0.1), patients with chronic persistent hepatitis (3.5 +/- 0.5), patients with chronic active hepatitis (6.9 +/- 1.3) or patients with cirrhosis (5.8 +/- 1.1). In acute type B hepatitis, only polymeric immunoglobulin A antibody of either IgA1 or IgA2 subclass was detected. In contrast, in chronic infection, antibody to hepatitis B core antigen of IgA2 subclass was found in the polymeric form, but antibody of IgA1 subclass was detected in both polymeric and monomeric forms.

Antibodies, Monoclonal↗
PubMed1977

EBV specific secretory IgA in saliva of NPC patients. Presence of secretory piece in epithelial malignant cells.

Saliva samples from 59 patients with nasopharyngeal carcinoma (NPC) and from 20 normal individuals were studied to determine the nature and origin of the EBV-specific IgA in NPC saliva. About 50% of NPC saliva samples contained secretory IgA specific for EBV. The corresponding tumor IgA(alpha) was found in plasma cells surrounding the epithelial tumor cells and the secretory piece at the surface of epithelial cells. A slightly higher proportion of NPC saliva samples containing IgA was found in patients from Tunis than in samples from Hong Kong. Attention is drawn to the clinical value of the salivary IgA in diagnosis and monitoring of treatment of NPC.

Antibody Specificity↗
PubMed1994

Polarized sorting of the polymeric immunoglobulin receptor in the exocytotic and endocytotic pathways is controlled by the same amino acids.

Polarized epithelial cells can sort plasma membrane proteins to the apical or basolateral domain either by direct targeting from the trans-Golgi network (TGN) or by targeting to one surface, followed by endocytosis and transcytosis to the opposite surface. In Madin-Darby canine kidney (MDCK) cells, targeting of the polymeric immunoglobulin receptor (pIgR) to the basolateral surface is controlled by a sorting signal residing in the membrane proximal 17 amino acids of the cytoplasmic domain of this receptor. We have recently found that individual mutations at any of three residues in this signal, His656, Arg657 and Val660, substantially decrease targeting from the TGN to the basolateral surface and correspondingly increase targeting from the TGN to the apical surface. Here we report that these mutations decrease the recycling of basolaterally endocytosed pIgR to that surface, and correspondingly increase its transcytosis to the apical surface. This effect occurred in mutant pIgRs that either contained the full-length cytoplasmic domain or were truncated to contain only the 17-residue basolateral targeting signal, and was independent of phosphorylation of pIgR at Ser664. Our results indicate that polarized sorting of the pIgR in the endocytotic and exocytotic pathways are controlled by the same amino acids.

Amino Acid Sequence↗
PubMed1981

Differentiation of human breast carcinomas: an immunohistological study of appropriate and inappropriate protein production.

Secretory piece of immunoglobulin A, a product of normal breast tissue, and beta 1 pregnancy-specific glycoprotein, a product of syncytiotrophoblast of placenta, have been demonstrated in breast carcinomas by an indirect immunoperoxidase method. A close relationship has been found between the site of staining within cells and tumour structure for both secretory piece, the appropriate protein, and beta 1 pregnancy-specific glycoprotein, the inappropriate protein. The reaction was at the periphery of cells in areas of tubular differentiation and was diffusely intracytoplasmic in solid groups of tumour cells. The poorly differentiated carcinomas have a low incidence of detection for both antigens but the tumours showing good histological differentiation appear to be functionally heterogeneous with some being negative for both proteins, some staining for the appropriate secretory piece of immunoglobulin A and the inappropriate beta 1 pregnancy-specific glycoprotein and only one out of 12 producing the appropriate protein alone.

Breast Neoplasms↗
PubMed1996

A central body region defined by a position-specific molecule in the planarian Dugesia (Girardia) tigrina: spatial and temporal variations during regeneration.

We have isolated a monoclonal antibody, TCEN49, that displays position-specific binding to the central body region of the planarian Dugesia (Girardia) tigrina. TCEN49 binds to all cell types of the central area with the exception of epithelial cells. Labeled cells are more related by position than by lineage. In the intact organism, boundaries between labeled and unlabeled regions are very sharp and in a dynamic state as they shift in relative position along the body axis during growth and degrowth. During regeneration, TCEN49 antigen is present in the area which will form the central region before it is morphologically apparent. Moreover, when animals are cut through the central region, TCEN49 label fades quickly from those regions determined to become head or tail well before morphogenesis takes place. Taken together, these data suggest that expression of TCEN49 antigen is very sensitive to positional information changes and that it could be involved in the expression of central-body positional identity. TCEN49 antigen is a glycoprotein with an apparent molecular weight of 4.5 kDa, as determined by gel immunoblotting. Immunogold light and electron microscopy demonstrate that the main location of TCEN49 antigen is intracellular (granular components of secretory cells and, to a lesser extent, clear cytoplasmic vesicles and heterochromatin blocks), though it is also detected in the extracellular matrix. TCEN49 antigen represents the first position-specific molecule reported in planarians to date.

Animals↗