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N E Richardson

Publications and source records attributed to N E Richardson.

At least 19 recordsLinked to original sources
PubMed1999

The philosophy of benchmark testing a standards-based picture archiving and communications system.

The Department of Defense issued its requirements for a Digital Imaging Network-Picture Archiving and Communications System (DIN-PACS) in a Request for Proposals (RFP) to industry in January 1997, with subsequent contracts being awarded in November 1997 to the Agfa Division of Bayer and IBM Global Government Industry. The Government's technical evaluation process consisted of evaluating a written technical proposal as well as conducting a benchmark test of each proposed system at the vendor's test facility. The purpose of benchmark testing was to evaluate the performance of the fully integrated system in a simulated operational environment. The benchmark test procedures and test equipment were developed through a joint effort between the Government, academic institutions, and private consultants. Herein the authors discuss the resources required and the methods used to benchmark test a standards-based PACS.

Benchmarking↗
PubMed1997

Highlights of the Digital Imaging Network-Picture Archiving and Communications System Project.

The Department of Defense issued its requirements for a Digital imaging Network-Picture Archiving and Communications System (DIN-PACS) in a Request for Proposals to industry in January, 1997. The DIN-PACS shall be an open systems network of digital devices designed for the effective acquisition, transmission, display and management of diagnostic imaging studies. This network is primarily based on two international standards, Digital imaging and Communications in Medicine (DICOM) and Health Level 7 (HL7). The DIN-PACS is required to communicate in a bidirectional manner with the Department of Defense standard hospital information system called the Composite Health Care System (CHCS) through an HL7 compliant interface. The DIN-PACS model and its published specifications stress functionality and performance rather than system architecture to allow industry to propose optimal approaches for implementation. This paper discusses the functional requirements of the DIN-PACS in terms of its internal operations as well as its communication with external systems and components. This is a US government work. There are no restrictions on its use.

Diagnostic Imaging↗
PubMed1988

A soluble CD4 protein selectively inhibits HIV replication and syncytium formation.

The CD4 (T4) molecule is expressed on a subset of T lymphocytes involved in class II MHC recognition, and is probably the physiological receptor for one or more monomorphic regions of class II MHC (refs 1-3). CD4 also functions as a receptor for the human immunodeficiency virus (HIV) exterior envelope glycoprotein (gp120) (refs 4-9), being essential for virus entry into the host cell and for membrane fusion, which contributes to cell-to-cell transmission of the virus and to its cytopathic effects. We have used a baculovirus expression system to generate mg quantities of a hydrophilic extracellular segment of CD4. Concentrations of soluble CD4 in the nanomolar range, like certain anti-CD4 monoclonal antibodies, inhibit syncytium formation and HIV infection by binding gp120-expressing cells. Perhaps more importantly, class II specific T-cell interactions are uninhibited by soluble CD4 protein, whereas they are virtually abrogated by equivalent amounts of anti-T4 antibody. This may reflect substantial differences in CD4 affinity for gp120 and class II MHC.

Animals↗
PubMed1988

Molecular cloning of the common acute lymphoblastic leukemia antigen (CALLA) identifies a type II integral membrane protein.

Common acute lymphoblastic leukemia antigen (CALLA) is a 100-kDa cell-surface glycoprotein expressed on most acute lymphoblastic leukemias and certain other immature lymphoid malignancies and on normal lymphoid progenitors. The latter are either uncommitted to B- or T-cell lineage or committed to only the earliest stages of B- or T-lymphocyte maturation. To elucidate to homogeneity, obtained the NH2-terminal sequence from both the intact protein and derived tryptic and V8 protease peptides and isolated CALLA cDNAs from a Nalm-6 cell line lambda gt10 library using redundant oligonucleotide probes. The CALLA cDNA sequence predicts a 750-amino acid integral membrane protein with a single 24-amino acid hydrophobic segment that could function as both a transmembrane region and a signal peptide. The COOH-terminal 700 amino acids, including six potential N-linked glycosylation sites compose the extracellular protein segment, whereas the 25 NH2-terminal amino acids remaining after cleavage of the initiation methionine form the cytoplasmic tail. CALLA+ cells contain CALLA transcripts of 2.7 to 5.7 kilobases with the major 5.7- and 3.7-kilobase mRNAs being preferentially expressed in specific cell types.

Amino Acid Sequence↗
PubMed1988

Adhesion domain of human T11 (CD2) is encoded by a single exon.

The 50-kDa T11 (CD2) T-lymphocyte surface glycoprotein facilitates physical adhesion between T-lineage cells and their cognate cellular counterparts (cytotoxic T-lymphocytes-target cells, helper T lymphocytes-antigen-presenting cells, or thymocytes-thymic epithelium) as well as signaling through the antigen-specific T3-Ti receptor complex. To examine the relationship between the structure and function of the T11 molecule, we have utilized a baculoviral expression system to produce milligram quantities of the hydrophilic extracellular T11 segment. Enzyme cleavage, microsequencing, and HPLC analyses of the expressed protein in conjunction with genomic cloning information show that the domain involved in cellular adhesion is encoded by a single 321-base-pair exon.

Amino Acid Sequence↗
PubMed1988

Binding site for human immunodeficiency virus coat protein gp120 is located in the NH2-terminal region of T4 (CD4) and requires the intact variable-region-like domain.

The external segment of the T4 (CD4) glycoprotein functions as the T-cell surface receptor for human immunodeficiency virus by binding the major viral coat protein (gp120) with relatively high affinity. To more precisely define the region of T4 involved in gp120 interaction, we used purified, soluble forms of T4 anchor-minus polypeptides (produced in a baculovirus system) in conjunction with proteolytic fragmentation, microsequencing, and a specific T4-gp120 binding assay. The results indicate that the NH2-terminal region of T4 including the immunoglobulin variable-region-like domain is required for gp120 interaction. In contrast, the COOH-terminal half of the molecule, containing the two potential N-linked glycosylation sites, is not necessary. Furthermore, reduction of intrachain disulfide bonds in the T4 molecular abrogates gp120 binding, thereby strongly implying that the binding site for gp120 is dependent on the stabilized domain structure of the active binding region.

Amino Acid Sequence↗
PubMed1988

Efficacy and specificity of monoclonal antibodies to progesterone in preventing the establishment of pregnancy in the mouse.

Anti-progesterone monoclonal antibody prevents the establishment of pregnancy in BALB/c mice by the prevention of implantation when injected i.p. 32 h after mating. To determine the specificity of this effect, mice were injected with immune and non-immune purified mouse immunoglobulins. The results show that anti-implantation efficacy was due to high-affinity antibody which bound progesterone since two further mouse immunoglobulin (Ig) G1 preparations, mouse IgA and mouse IgM which failed to bind the steroid, had no effect on pregnancy rates. From a panel of anti-progesterone monoclonal antibodies, six with a high affinity (affinity constant, 0.24-0.80 litres/nmol) and specificity for progesterone were selected for additional studies. Anti-implantation efficacy for five antibodies was similar, with a 50% effective dose within the range of 0.8-2.0 nmol. Antibody reached high concentrations in plasma within 12 h after i.p. injection, and declined with a half-life of about 80 h. Purified F(ab')2 fragments of antibody also bound progesterone, but were less effective than the native molecule in blocking pregnancy. The results show that implantation in the mouse can be blocked by a high-affinity antibody that binds progesterone and which is removed from the blood at a slow rate.

Animals↗
PubMed1987

Human T lymphocyte activation.

The T lymphocyte receptor for antigen and histocompatibility molecules is a molecular complex comprised of five polypeptide chains. Both the 49KD alpha and 43KD beta chains are immunoglobulin-like and thus contain variable domains responsible for ligand binding. In contrast, the 20-25KD T3 gamma, delta and epsilon chains are monomorphic structures presumably involved in transmembrane signalling. The alpha and beta subunits are disulfide bonded to each other and held in noncovalent association with the T3 chains. T3-Ti receptor crosslinking leads to conformational modification of a second T lineage specific molecule, termed the 50KD T11 structure and in turn, protein kinase C activation, elevation in intracytoplasmic free calcium and Na+/H+ antiport stimulation.

Cell Differentiation↗
PubMed1987

Molecular cloning and expression of T11 cDNAs reveal a receptor-like structure on human T lymphocytes.

The T11 (CD2) sheep-erythrocyte-binding protein is a T-cell surface molecule involved in activation of T lymphocytes and thymocytes, including those lacking the T3-Ti antigen-receptor complex. The primary structure of T11 was deduced from protein microsequencing and cDNA cloning. The mature human protein appears to be divided into three domains: a hydrophilic 185 amino acid external domain bearing only limited homology to the T-cell surface protein T4 and the immunoglobulin kappa light chain variable region, a 25 amino acid hydrophobic transmembrane segment, and a 126 amino acid cytoplasmic domain rich in prolines and basic residues. Transfection of cDNAs encoding either the 1.7- or the 1.3-kilobase T11 mRNA into COS-1 cells resulted in expression of surface T11 epitopes as well as sheep-erythrocyte-binding capacity. The predicted structure is consistent with the possibility that T11 functions in signal transduction.

Amino Acid Sequence↗
PubMed1987

Functional and molecular aspects of human T lymphocyte activation via T3-Ti and T11 pathways.

Two pathways of human lymphocyte activation are known to exist on T-lineage cells. The first involves the T-lymphocyte receptor for antigen (T3-Ti) which operates in conjunction with gene products of the MHC complex and is a molecular complex composed of 5 polypeptide chains. Both the 49KD alpha and 43KD beta chains are immunoglobulin-like and thus contain variable domains responsible for ligand binding. In contrast, the 20-25KD T3 gamma, delta and epsilon chains are monomorphic structures presumably involved in transmembrane signalling. The alpha and beta subunits are disulfide bonded to each other and held in noncovalent association with the T3 chains. The second pathway involves the 50KD T11 sheep erythrocyte binding protein. The T11 pathway is operational during early intrathymic ontogeny, prior to T3-Ti receptor expression. Under physiologic conditions, T3-Ti and T11 pathways appear to function in series with T11, representing a more "nuclear proximal" structure. However, each pathway, independently of the other, can activate the phosphoinositol cascade and lead to elevation in cytosolic free calcium. The latter is critical for transcriptional activation of the endogenous IL-2 gene. The ability of the T3-Ti complex to regulate T11-mediated activation is discussed with reference to its possible role in thymic selection.

Antigens, Surface↗
PubMed1986

Retraction of data.

Explore the source record for details and available documents.

Retraction Notice↗
PubMed1986

A lymphokine that activates the cytolytic program of both cytotoxic T lymphocyte and natural killer clones.

A 10-12 kD lymphokine, herein termed TCAF, was recently shown to be secreted from Th after crosslinking of their antigen/MHC (T3-Ti) receptors. TCAF stimulates resting T lymphocyte proliferation via binding to surface components of the T11 pathway. To determine whether TCAF could induce antigen-independent activation of the lytic machinery of cytotoxic cells, the present studies were conducted. In the presence of TCAF, both T8+ class I MHC-specific and T4+ class II MHC-specific cytotoxic T cell clones were induced to kill targets, including those lacking the appropriate MHC molecules. This effect was unique to TCAF, since IL-1, IL-2, IFN-gamma could not stimulate lytic activity. Furthermore, both T3+T11+ and T3-T11+ NK clones were triggered to lyse NK-resistant target cells. These findings suggest that TCAF can function in an antigen-independent fashion to amplify cytotoxic effector responses.

Antibodies, Monoclonal↗
PubMed1986

Identification of a T helper cell-derived lymphokine that activates resting T lymphocytes.

A novel lymphokine with apparent molecular size of 10 to 12 kilodaltons is secreted from helper T cell clones within hours after cross-linking their T cell antigen-MHC (major histocompatibility complex) receptors (T3-Ti). This lymphokine, termed interleukin-4A (IL-4A), stimulates resting lymphocytes by binding to a surface component (or components) of the alternative T11 pathway and subsequently by inducing interleukin-2 (IL-2) receptors. The activation process is neither dependent on antigen specificities of the recruited population or the presence of macrophages. It appears, therefore, that IL-4A is a mediator involved in amplifying the T cell immune response.

Antibodies, Monoclonal↗
PubMed1983

Distinct populations of class II molecules identified by monoclonal antibodies.

Binding inhibition and sequential immunoadsorption studies with two rat monoclonal antibodies have been used to demonstrate the existence of distinct populations (isotypes) of HLA-DR like (class II) molecules in human B lymphoma cell lysates. The structures of the molecules isolated by these two reagents have been compared by peptide 'mapping' and appear to be closely similar.

Antibodies, Monoclonal↗
PubMed1981

The mechanism of interaction between chlorhexidine digluconate and poly(2-hydroxyethyl methacrylate).

The extent of the interaction between chlorhexidine digluconate and poly(2-hydroxyethyl methacrylate), (PHEMA), is independent of temperature between 22-50 degrees C which is consistent with an ion-ion interaction mechanism. Different contact lens materials exhibit different affinities for chlorhexidine digluconate, the extent of uptake correlating in rank order with the number of free carboxylic acid sites in the polymers. Esterification of the carboxyl groups with diazomethane, resulted in a reduction in the affinity of the treated polymers for chlorhexidine to a near basal level. The uptake of chlorhexidine in soaking solution experiments involving lenses made from PHEMA and the more ionic material, poly(2-hydroxyethyl methacrylate-co-isobutyl methacrylate-co-methacrylic acid), was consistent with their carboxylate content. However, the fraction of bound disinfectant released was lower from the terpolymer, suggesting there are differences in bonding strengths between chlorhexidine and different contact lens hydrogels.

Adsorption↗
PubMed1980

The use of polyamide coatings for selective adsorption control on activated charcoal.

Polymer-coated, activated charcoal granules have found considerable use for the direct detoxification of blood in cases of uraemia and drug overdose. Although polymer coating materials are presently selected for their biocompatibility, more selective polymers could be used to increase the adsorption capacity for specific drugs and toxins. To gain an understanding of the fundamental factors influencing these adsorbent systems, we have investigated a possible selective coating material, nylon 6 and studied its influence on adsorption rates of simple model compounds when applied as a thin coat to activated charcoal granules. Thermodynamic studies have shown that phenolic compounds interact with the polymer by a hydrogen bonding mechanism, whereas nonphenolic compounds probably bind less strongly due to Van der Waals type interactions. Kinetic studies have shown that the selectivity of charcoal granules for phenolic compounds was increased by coating the granules with a thin layer of nylon 6. The increase in selectivity is probably a result of the different binding mechanism between solute and the polymer. These studies have shown that possible selective coatings may be evaluated more effectively on the basis of simple preliminary drug-plastics interaction studies.

Adsorption↗