Search PubMed⌕ Search

Biomedical subjects

J Fawcett

Publications and source records attributed to J Fawcett.

At least 127 records · Page 7Linked to original sources
PubMed1994

Normal human tissues, in addition to some tumors, express multiple different CD44 isoforms.

At least 20 different isoforms of the human CD44 lymphocyte-homing receptor/hyaluronan receptor have been described to date that arise from the differential splicing of up to 10 alternative exons (termed v1-v10) encoding the membrane-proximal extracellular domain. Although numerous analyses at the mRNA level have indicated tissue-specific expression of CD44 variants, few analyses have been performed at the protein level because of limited availability of suitable monoclonal antibodies. Recently, however, exon-specific monoclonal antibodies have been generated using bacterial fusion proteins, and these have been reported to detect high levels of vCD44 containing the v6 exon on human tumors. Together with earlier evidence linking this particular exon with tumor metastasis in the rat, these latter experiments have led to the interpretation that v6 splice variants play a causative role in tumor dissemination. In this paper we describe the use of a new and comprehensive panel of CD44 exon-specific monoclonal antibodies generated against a recombinant CD44(v3-10)-immunoglobulin chimera to study vCD44 expression in a large number of normal and neoplastic tissues. We show that the expression of vCD44 varies greatly among different human tumors and that some express either very low levels of vCD44 or no CD44 at all. Furthermore, we demonstrate that expression is not limited to isoforms containing the v6 exon but includes variants carrying v3, v4/5, and v8/9. Additionally, normal epithelial tissues are shown to express considerable levels of these same vCD44 isoforms. Such results argue against a ubiquitous role for vCD44 isoforms in promoting tumor growth and metastasis.

Antibodies, Monoclonal↗
PubMed1994

The N-domain of the biliary glycoprotein (BGP) adhesion molecule mediates homotypic binding: domain interactions and epitope analysis of BGPc.

The biliary glycoproteins (BGPs) represent a group of at least eight differentially spliced molecules belonging to the carcinoembryonic antigen (CEA) subgroup of the CEA family. These molecules are recognized by the CD66 monoclonal antibodies (MoAbs) and function as homotypic and heterotypic adhesion molecules. The extracellular region of the BGPc splice variant comprises an N-terminal IgV-like domain and three IgC2-set domains (A1, B1, and A2). Using soluble recombinant BGP domain variants, we demonstrate in this report that the N-terminal domain mediates homotypic adhesion. Furthermore, this adhesion is both temperature- and cation-dependent. The soluble domain variants of BGP are ideal molecules for epitope mapping. Using these constructs, we have mapped 11 MoAbs that react with the CEA family to different domains of BGPc and have shown that the CD66 MoAbs, YTH71.3.2 and CLBgran 10 (M38), recognize epitopes in the N-terminal domain.

Animals↗
PubMed1994

CD66 identifies the biliary glycoprotein (BGP) adhesion molecule: cloning, expression, and adhesion functions of the BGPc splice variant.

Within the hematopoietic lineage, the monoclonal antibody (MoAb) CD66 reacts with cells of the granulocyte lineage, but not with the majority of progenitor cells from human bone marrow. Our previous studies have shown that CD66 binds specifically to at least three carcinoembryonic antigen (CEA) superfamily members, ie, CEA itself, nonspecific cross-reacting antigen (NCA), and CGM1, but not to CGM6 (NCA-95). In this report, we show that CD66 will also identify the biliary glycoproteins (BGP). A full-length cDNA for the BGPc molecule (a cytoplasmic splice variant of BGPa) was isolated by expression cloning using the CD66 MoAbs. This protein has an identical extracellular and transmembrane sequence to BGPa with one N-terminal IgV like domain, three IgC-like extracellular domains (A1, B1, and A2), plus a transmembrane domain, but the cytoplasmic domain is spliced by 53 nucleotides. Reverse transcriptase-polymerase chain reaction experiments show that this splice variant can be detected in colonic carcinoma cell lines, in primary colonic adenocarcinomas, and in myeloid and B-cell lines to varying degrees. Quantitative analyses of BGPc RNA expression by RNase protection indicate that abundant levels occur only in the colonic, but not in the hematopoietic, cell lines tested. Studies presented here show that BGPc mediates homotypic adhesion and suggest that the cytoplasmic splicing does not alter the initial homotypic adhesion properties of BGPa.

Amino Acid Sequence↗
PubMed1994

Astrocytes and axon regeneration in the central nervous system.

The failure of axons to regenerate in the central nervous system is mainly due to inhibition by the environment, made up of astrocytes and oligodendrocytes, which surrounds regions of damage. Both cell types are inhibitory to axon regeneration, and it seems likely that each will have to be neutralised before significant axon regeneration is achieved. Axons regenerate over the surface of astrocytes grown in normal monolayer culture but not through three-dimensional astrocyte cultures. Astrocyte cell lines have been created, some of which resemble embryonic astrocytes and form a loose tissue with extensive extracellular space which permits axon regeneration, and others which model astrocytes in the damaged brain having little extracellular space and much extracellular matrix material. There is no correlation between the inhibitory effect on axons and the expression of cell adhesion molecules, proteases, protease inhibitors, and a variety of extracellular matrix molecules. However, extracellular matrix produced by inhibitory cell lines is inhibitory to axon regeneration, while that produced by permissive cell lines is not. This difference depends on the production of a chondroitinase-sensitive proteoglycan which can block the neurite-inducing effects of laminin so that treatment of inhibitory extracellular matrix with chondroitinase renders it more permissive to axon regeneration.

Animals↗
PubMed1994

Use of alternative health therapies by people with multiple sclerosis: an exploratory study.

Sixteen people with multiple sclerosis (MS) responded to a semi-structured questionnaire about their experiences with alternative therapies. No definition of alternative therapies was provided. Physical therapy, counseling, nutrition, and massage were the most frequently used alternative therapies. Other therapies included acupuncture, occupational therapy, aquatic therapy, Therapeutic Touch, yoga, passive exercise, and removal of mercury alloy tooth fillings. Almost two thirds of the respondents reported seeking an alternative health practitioner because traditional physicians offered no cure for MS. Just under one third of the respondents stated that the quality of their lives was improved by alternative therapies.

Adult↗
PubMed1994

Antidepressants: partial response in chronic depression.

Although most studies of chronic depression show significant improvements with antidepressants versus placebo, the average Hamilton Depression Rating Scale results attained in the active-treatment group range between 10 and 14, suggesting that many patients only partially responded and failed to reach premorbid levels of symptom remission. Studies on the fate of these patients suggest that they are much more vulnerable to relapse, work impairment and suicide. Thus, partial response may be one form of treatment resistance, falling between total failure of response in a minority of patients, and a tendency to relapse or recur despite adequate maintenance treatment. Further study is needed to address the problem of improving the quality of response and attempting to reduce the detrimental effects of depressive illness in terms of relapse and recurrence.

Antidepressive Agents↗
PubMed1994

Overview of mood disorders: diagnosis, classification, and management.

This discussion of the diagnosis, classification, and epidemiology of clinical depression includes details of the associated physical morbidity, mortality, and impairment. Treatment approaches to depressive disorders are categorized with an emphasis on medication management, including improved treatment efficacy and progress with respect to side effects and toxicity. Although considerable advances have been made, with 18 antidepressant compounds being available and the impending release of two new antidepressant compounds in 1994, no one agent has demonstrated greater efficacy than another. Currently available studies suggest that only 21-42% of patients entered into treatment reach full recovery, while 20% of patients do not respond to available treatment but remain chronically depressed. Thus, the development of more efficacious agents that will produce complete remissions in patients who now achieve only partial treatment responses is a major challenge for biochemical, pharmacological, and clinical research of the treatment of mood disorders.

Affective Disorders, Psychotic↗
PubMed1993

The heparin binding PECAM-1 adhesion molecule is expressed by CD34+ hematopoietic precursor cells with early myeloid and B-lymphoid cell phenotypes.

The platelet-endothelial cell adhesion molecule-1 (PE-CAM-1), defined by the CD31 monoclonal antibody (MoAb), was initially described as a cell-cell adhesion molecule mediating both homotypic and heterotypic adhesion. In this report, we show that enriched CD34+ human hematopoietic progenitor cell populations, containing early myeloid, erythroid, and multipotential progenitor cells, are CD31+. Analyses of CD34+ cell lines representing early myeloid, multipotential, and pre-pre-B-lymphoid progenitors indicate that precursors of both myeloid and B-lymphoid cells express PECAM-1 at high levels. Three-color flow-cytometric analyses also show that normal human bone marrow CD31+ CD34+ subsets coexpress myeloid (CD33) or B-lymphoid (CD19, CD10) markers. Except for the monocytic cell line, U937, all CD34- cell lines tested, which represent more mature stages of the myeloid, erythroid, and lymphoid lineages, expressed substantially lower or negligible levels of PECAM-1. Western blotting studies indicated that the CD31 MoAb, JC/70A, detected molecules in the 120- to 140-kD molecular weight range on the monocytic CD34- CD33+ CD31+ cell line, U937; on the CD34+ CD31+ CD33+ CD19- multipotential/lymphomyeloid precursor cell lines, KG1 and KG1B; on the CD34+ CD31+ CD19+ CD10+ CD33- precursor pre-pre-B-cell line, MIK-ALL; and on a CD34(+)-enriched precursor cell population from normal human bone marrow. A single molecular weight species was generally observed with enriched membrane preparations, whereas two PECAM-1 molecules were present in whole-cell lysates of cell lines and the CD34+ bone marrow cell subset. Preliminary studies show that a proportion of the PECAM-1 molecules on the lymphomyeloid/multipotential progenitor cell line, KG1, and on the monocytic cell line, U937, binds to heparin-sepharose. A soluble form of PECAM-1 also binds heparin-sepharose. The high level of expression of PECAM-1 on CD34+ cells suggests that this glycoprotein may function as a heterotypic adhesion molecule, possibly mediating multipotential, myeloid, and early-B-lymphoid precursor cell interactions with stromal cells and extracellular matrix molecules via heparan sulfate proteoglycans. It may also act as a homotypic adhesion molecule by interacting with PECAM-1 on bone marrow stromal macrophage-like cells and endothelial cells or on endothelial cells during stem/progenitor cell migration. Thus, this molecule has the potential importance of directing both lineage commitment and trafficking of early hematopoietic progenitor cells.

Adult↗
PubMed1993

Macrosialin, a mouse macrophage-restricted glycoprotein, is a member of the lamp/lgp family.

Macrosialin is a heavily glycosylated transmembrane protein of 87-115 kDa, highly and specifically expressed by mouse tissue macrophages, and to a lesser extent by dendritic cells. We have isolated cDNA clones encoding macrosialin from a thioglycollate-elicited peritoneal macrophage cDNA library by transient expression in COS cells and panning with the anti-macrosialin monoclonal antibody FA/11. A single 1.3-kilobase macrosialin transcript was detected in both untreated and phorbol 12-myristate 13-acetate-stimulated RAW cells. The cDNA sequence predicts a type I integral membrane protein of 326 residues with a heavily glycosylated extracellular domain of 306 residues containing nine potential N-linked glycosylation sites and numerous potential O-linked glycosylation sites. The extracellular domain consists of two distinct regions, separated by an extended 12 residue proline-rich hinge; a membrane-distal mucin-like domain of 89 residues containing short peptide repeats and consisting of 44% serine and threonine residues; and a membrane proximal domain of 170 residues, which has significant sequence homology to a family of lysosomal associated glycoproteins known as the lamp-1 group. Macrosialin is the murine homologue of the human macrophage glycoprotein CD68 (72% identity, 80% similarity). Both proteins are preferentially expressed by macrophages and share the same bipartite structure having a mucin-like domain and a domain common to the lamp family. Macrosialin and CD68 are the first examples of a lamp family protein with a restricted cell-type-specific expression. They may have evolved from the lamps to carry out specialized functions in dedicated phagocytic cells.

Amino Acid Sequence↗
PubMed1993

Immunohistochemical identification of rat adrenal cortical tissue in situ, in vitro, and in intracerebral adrenal grafts.

We have used a polyclonal antibody to the biosynthetic adrenocortical enzyme, 3-beta-hydroxysteroid dehydrogenase, to demonstrate rat adrenal cortical tissue in situ, in vitro, and in intracerebral adrenal suspension grafts. This technique provides a means of identifying the degree to which adrenal medulla grafts are in practice contaminated by adrenal cortical cells and allows analysis of the extent to which the presence of cortical cells influences the viability, differentiation, and functional efficacy of intracerebral adrenal grafts.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

A selective tachykinin receptor agonist promotes differentiation but not survival of rat chromaffin cells in vitro.

Rat chromaffin cells display phenotypic plasticity postnatally. In the presence of glucocorticoids, they retain a chromaffin cell phenotype, whilst in the presence of nerve growth factor and the absence of glucocorticoids they adopt a sympathetic neuronal phenotype. The tachykinins have some of the characteristics of a neurotrophic factor and are present in the form of a substance P afferent input in the rat adrenal medulla. We investigated the effects of stable NK1 and NK2 tachykinin receptor agonists, Ava[L-Pro,N-Me-Leu-10]SP7-11 (GR73632) and [Lys-3,Gly-8,R-Lac-Leu-9]NKA3-10 (GR64349), respectively, on the survival and phenotype of P5-7 rat chromaffin cells in vitro. GR73632 promoted neurite outgrowth, characteristic of the sympathetic neuronal phenotype, in the absence of NGF and glucocorticoids, but was without effect on survival after 2 weeks in culture. GR64349 was without effect.

Adrenal Glands↗
PubMed1993

The morbidity and mortality of clinical depression.

Clinical depression is associated with social, occupational and physical impairment and mortality. Furthermore, data are reviewed which have related the severity of depressive symptoms, such as anhedonia, psychic anxiety, panic attacks, alcohol abuse, insomnia and diminished concentration in depressed patients, to suicide within 1 year. By contrast, hopelessness, suicidal ideation, and prior suicide attempts were related to suicide within 2-10 years after examination, but did not correlate with suicide within the first year of follow-up. It is concluded that clinical depression continues to be associated with significant morbidity and mortality, despite progress which has been made in its treatment.

Cause of Death↗
PubMed1993

Acute effects of ethanol on hepatic endocytosis and processing of insulin in perfused rat liver.

This study utilizes the perfused rat liver combined with subcellular fractionation and compartmental analysis to investigate the effects of ethanol on hepatic uptake, endocytosis, and processing of insulin. At 4 min after the start of a 2-min pulse of radiolabeled insulin, increasing ethanol concentrations progressively inhibited insulin uptake by the liver (57% at 50 mM ethanol). Subcellular fractionation of the perfused livers showed a progressive shift in distribution from a predominantly endosomal location (control) to a bimodal distribution between endosomes and plasma membrane. This could be largely accounted for by a specific reduction in the endosome-associated insulin. Binding studies showed no changes in the binding properties of the plasma membrane insulin receptor. Compartmental analysis of the perfusate efflux curves confirmed the lack of effect of ethanol on the binding constants but showed a significant decrease in the endocytic rate constant (50%) together with an increase in the retroendocytic rate constant (33%). Simulation studies with the compartmental model showed that these changes could account for the observed decrease in uptake by the liver. No changes were found in the subsequent endocytic degradation of insulin.

Animals↗