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Biomedical subjects

D Richards

Publications and source records attributed to D Richards.

At least 127 records · Page 7Linked to original sources
PubMed1990

IgG subclass antibody production in human serum sickness.

The role of IgG-subclass antibodies in the spectrum of immunologic disorders has not yet been fully defined. In an attempt to understand its role in an immune complex-mediated disease, we studied patients who developed serum sickness (SSX) after treatment with an equine-derived immunoglobulin, antithymocyte globulin (ATG), for bone marrow failure. The predominant IgG subclass produced was IgG1, representing nearly 80% of all IgG anti-ATG activity present. The appearance of IgG anti-ATG antibodies and C1q-containing immune complexes was closely correlated with symptoms of SSX. Although other antibody isotypes were present and may have contributed to the patients' symptoms, it is evident that IgG1 is the predominant IgG subclass produced in human SSX caused by a heterologous protein.

Adolescent↗
PubMed1990

Interleukin-1 regulation of procollagenase mRNA and protein in periodontal fibroblasts in vitro.

An in vitro model is used to investigate the hypothesis that activated fibroblasts produce collagenolytic activity in inflammatory sites. Interleukin-1, a cytokine present in the gingiva and crevicular fluid of periodontitis patients, has multiple biologic activities including the ability to stimulate collagenase in dermal and synovial fibroblasts. In this report IL-1 is tested on gingival (GF) and periodontal ligament fibroblasts (PLF) for its ability to increase collagenolytic activity and procollagenase mRNA and protein. GF produce a 3- to 7-fold increase in collagenase activity, while PLF collagenase activity is rarely increased above control amounts by IL-1 treatment. In contrast, both cell types demonstrate an increase in procollagenase protein production with IL-1 treatment. RNA from both GF and PLF contain procollagenase mRNA as demonstrated when northern blots of fibroblast total RNA are hybridized with the cDNA for human procollagenase. Treatment with IL-1 increases the steady-state levels of this message in GF by up to 10-fold in 48 hours when measured with dot blot analysis standardized for poly-A RNA. PLF also produce up to 7 times more message at the same dose and time. Since fibroblasts present in the lesion are exposed to inflammatory cell products it is possible that the production of collagenase by these cells could result in the destruction of the periodontal fibrous attachment.

Blotting, Western↗
PubMed1990

Ten steps to successful grant writing.

Major changes in the allocation of health care funds requires that nurse administrators develop excellent grant writing skills. However, many nurse managers indicate they need assistance in developing grant proposals. A step-by-step approach to writing a grant proposal is presented. While it is targeted primarily to the novice grant writer, the seasoned grant writer will particularly benefit from the discussion of the common mistakes.

Financing, Organized↗
PubMed1989

Ultrasensitive enzyme-linked immunosorbent assay (ELISA) for the detection of picogram quantities of IgE.

Existing methods of measuring IgE in in vitro peripheral blood lymphocyte (PBL) cultures are not sufficiently sensitive to detect IgE when it is present in small amounts. This paper describes a modification of a two-site ELISA which increases the sensitivity of the assay 10-20-fold. By using the Fab' fragment of either rabbit or mouse monoclonal anti-IgE conjugated to alkaline phosphatase (AP) as the detector, the background of the assay was reduced sufficiently to permit signal amplification, using a commercially available amplified AP substrate. With this assay as little as 10 pg/ml of IgE could be detected. The interassay coefficient of variation was 15-18% between 1200 and 100 pg/ml IgE (n = 14) and there was a good correlation with a commercial IgE radioimmunoassay (RIA) (r = 0.98, n = 38).

Alkaline Phosphatase↗
PubMed1989

The effect of glucagon on esophageal peristalsis and clearance.

The effect of 0.5 mg intravenous glucagon on esophageal peristalsis and transit of water and barium was studied in nine healthy subjects by concurrent videofluoroscopy and manometry. Glucagon lowered manometric peristaltic amplitude in both mid- and distal esophagus. This reached significance (p = 0.0075) in the distal 3 cm of the esophagus 2 min after the injection. The efficiency of esophageal stripping was also reduced (increased proximal escape on fluoroscopy), and became significant (p = 0.05) at 2 min after the injection of glucagon.

Adolescent↗
PubMed1989

Serial studies on the functional affinity and heterogeneity of antibodies of different IgG subclasses to phospholipase A2 produced in response to bee-venom immunotherapy.

High functional affinity and high titer IgG4 antibodies to phospholipase A2 were produced by allergic patients in response to bee-venom immunotherapy. In contrast, the affinity of IgG1 antibodies decreased after immunotherapy, and both the titer and affinity of IgG1 antiphospholipase A2 remained significantly lower compared to IgG4 1 to 2 years after treatment. Analysis of affinity heterogeneity suggested a loss of IgG1 high-affinity antibody-producing clones during immunotherapy and a preferential expansion of IgG4 clones. High-affinity IgE antibodies were found in untreated allergic patients, and preliminary results suggest that immunotherapy may result in an early marked decrease in the affinity of IgE antibodies.

Adolescent↗
PubMed1989

The subclass of IgG antibody in allergic disease: II. The IgG subclass of antibodies produced following natural exposure to dust mite and grass pollen in atopic and non-atopic individuals.

In an attempt to understand the role of the different IgG subclasses in allergic disease, we have studied the subclass of IgG antibody to dust mite (HDM) and grass pollen (GP) produced as a result of natural exposure. Studies were carried out on 40 atopic children and 100 atopic adults who had never received immunotherapy. Thirty-two non-atopic adult controls were also studied. The specificity of the assay for IgG antibodies to dust mite was confirmed by inhibition with the homologous extract but not mite culture medium or fetal calf serum. IgG1 antibodies to HDM could be detected in most atopics (94%) and non-atopics (97%), and similar results were obtained for GP (81% and 100%, respectively). IgG4 antibodies to HDM were detected in more atopics (66%) than non-atopics (53%) and the difference was more marked for GP (72% vs. 19%). While the levels of IgG1 antibodies were not significantly different in the two groups, the levels of IgG4 antibodies were much lower in the non-atopics (P less than 0.001, Mann-Whitney U-test). These data show that all subjects were capable of recognizing and mounting an IgG1 antibody response to these inhaled antigens. Atopic individuals differed from normal subjects in the frequency with which they made IgG4 antibodies in response to natural exposure to both dust mites and pollen.

Adult↗
PubMed1989

Defined mutations in a small region of the brome mosaic virus 2 gene cause diverse temperature-sensitive RNA replication phenotypes.

The central portion of the brome mosaic virus (BMV) 2a protein represents the most conserved element among the related RNA replication components of a large group of positive-strand RNA viruses of humans, animals, and plants. To characterize the functions of the 2a protein, mutations were targeted to a conserved portion of the 2a gene, resulting in substitutions between amino acids 451 and 484. After the temperature profile of wild-type BMV RNA replication was defined, RNA replication by nine selected mutants was tested in barley protoplasts at permissive (24 degrees C) and nonpermissive (34 degrees C) temperatures. Four mutants did not direct RNA synthesis at either temperature. Various levels of temperature-sensitive (ts) replication occurred in the remaining five mutants. For two ts mutants, no viral RNA synthesis was detected at 34 degrees C, while for two others, an equivalent reduction in positive- and negative-strand RNA accumulation was observed. For one mutant, positive-strand accumulation was preferentially reduced over negative-strand accumulation at 34 degrees C. Moreover, this mutant and another displayed preferential suppression of genomic over subgenomic RNA accumulation at both 24 and 34 degrees C. The combination of phenotypes observed suggests that the 2a protein may play a role in the differential initiation of specific classes of viral RNA in addition to a previously suggested role in RNA elongation.

Amino Acid Sequence↗
PubMed1988

Increased speed and sensitivity, and reduced sample size of a micro-radioallergosorbent test (MRAST).

Performance of the radioallergosorbent test (RAST) in small volumes (MRAST) increases the efficiency with which both IgE antibody and 125I-anti-IgE bind. The rate at which antibody binds is increased up to 290-fold so that the assay can be completed in 60 min with comparable sensitivity to RAST. The increased speed of binding is achieved by the use of small incubation volumes which does not affect the rate at which bound antibody is dissociated. The resulting change in the equilibrium in favour of antibody binding yields a 10-fold increase in sensitivity which makes it possible to use as little as 5 microliter of sample compared with 50 microliter which is normal for RAST. MRAST can be used to measure IgE antibody in heel prick blood samples taken from babies, in rat sera and in other situations where the sample is in short supply.

Allergens↗
PubMed1988

The effects of interleukin 1 on collagenolytic activity and prostaglandin-E secretion by human periodontal-ligament and gingival fibroblast.

Fibroblasts of the periodontium may be involved in extracellular matrix degradation in response to inflammatory cytokines produced by mononuclear phagocytes. Interleukin 1 (IL1), one of these biologically-active agents, is produced by such cells when stimulated by lipopolysaccharide (LPS). Periodontal-ligament (PLF) and gingival fibroblasts responded to recombinant human IL1 beta and to media conditioned by LPS-stimulated mononuclear phagocytes by secreting prostaglandin E (PGE). This response was dose- and time-dependent. Stimulated gingival fibroblasts also produced about five- to ten-fold as much collagenolytic activity when compared to controls but PLF produced no more activity. On mixing the conditioned media from both fibroblast types, inhibitory activity was found in the PLF-culture medium. Thus gingival fibroblasts in particular may be involved in the pathogenesis of periodontal disease by responding to factors produced by inflammatory phagocytes.

Cells, Cultured↗
PubMed1987

Development of a semi-quantitative enzyme-linked immunosorbent assay (ELISA) for detection of human IgG subclass antibodies.

We have developed a sensitive enzyme-linked immunosorbent assay (ELISA) which measures antibodies to bee venom phospholipase A2 (PLA2) and hyaluronidase (HYAL), horse IgG, bovine casein, and the bacterium Streptococcus mutans in each of the four human IgG subclasses. For this purpose, we have used mouse monoclonal antibodies (McAb) specific for each subclass and one which showed 'pan-IgG' reactivity. Binding to human IgG was similar for all the McAb and dilution of human IgG resulted in similar dilution curves for each subclass. Results were expressed as arbitrary U ml-1 by comparing the optical density obtained with each subclass-specific McAb to a reference curve for total IgG antibody constructed using the 'pan-IgG' McAb. Close agreement was found between the total amount of IgG antibody and the sum of the antibody in each of the four subclasses (PLA2 r = 0.90, horse IgG r = 0.98, bovine casein r = 0.84, S. mutans r = 0.85), confirming that these assays provide semi-quantitative measurements of the amount of subclass-specific antibody.

Antibodies, Monoclonal↗
PubMed1987

Metabolism and urinary excretion of 5-amino salicylic acid in healthy volunteers when given intravenously or released for absorption at different sites in the gastrointestinal tract.

In six healthy subjects serum concentrations of 5 amino salicylic acid (5ASA) and acetyl 5ASA were measured for up to 24 hours, and urinary excretion over 48 hours. After an intravenous injection of 3.26 mmol 5ASA serum concentrations fell rapidly with a distribution half-life of 17 +/- 2 min and an elimination half-life of 42 +/- 5 min. After 45 minutes acetyl 5ASA became the dominant compound and after seven hours serum concentrations of both components were almost unrecordable. Orally ingested 5ASA in three preparations to ensure its release in the stomach, small intestine and ileocaecal region respectively gave lower serum concentrations and urinary excretion than those obtained after an intravenous infusion. Bioavailabilities which ranged from 19% for ileocaecal release to 75% for release in the upper gastrointestinal tract, were calculated from areas under the serum concentration curves. Urinary excretion of 5ASA and its acetyl metabolite over 48 hours was 78%, 52%, 55%, and 21% respectively of the dose given intravenously and orally for gastric, small intestinal and ileocaecal release.

Adult↗