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Biomedical subjects

D L Nelson

Publications and source records attributed to D L Nelson.

At least 271 records · Page 15Linked to original sources
PubMed1991

Dissociative effects in different prime domains.

These experiments were performed to examine the effects of different types of primes across variations in prime set size, prime strength, and prior study in verification and lexical decision tasks. The primes consisted of taxonomic category names, associates, or rhymes that defined either small or large sets of related concepts, and they were either strongly or weakly related to their targets. Targets either were or were not studied prior to the priming task. The results indicated that, for taxonomic primes, shorter decision latencies were obtained when set size was smaller and when the target was studied before the priming task. In contrast, for rhymes, neither set size nor prior study had reliable effects. For all three types of primes, decision latencies were faster for stronger than for weaker prime-to-target relationships. These findings are contrasted with the results of manipulating these variables in episodic tasks such as cued recall, and they are interpreted in the context of a components-of-processing approach.

Adult↗
PubMed1991

Soluble interleukin-2 receptor in juvenile rheumatoid arthritis.

Juvenile rheumatoid arthritis (JRA) is a chronic, relapsing, inflammatory childhood disease characterized by arthritis and systemic inflammation. At present there is no rapid, efficient laboratory method of assessing disease activity and degree of immune activation. We measured serum soluble interleukin 2 receptor (sIL-2R) levels in 85 samples from 72 patients (22 samples from patients with systemic JRA, 34 from polyarticular patients, 29 from pauciarticular patients, of which 10 were HLA-B27 positive). The mean sIL-2R level from patients was 1565 U/ml, which is significantly elevated compared to control values of 594 U/ml (p less than or equal to 0.005). The highest levels were seen in patients with systemic JRA (mean value 2121 U/ml) while the lowest values were seen in HLA-B27 positive (+) patients (mean value 899 U/ml). Patients with clinically active disease had significantly elevated levels (mean value 1745 U/ml) compared to patients with inactive disease (mean value 846 U/ml, p less than or equal to 0.01). Highest levels were seen in patients with active systemic JRA (mean value 2419 U/ml) while patients with pauciarticular JRA and B27 + JRA had the lowest sIL-2R levels (1167 and 1045 U/ml, respectively). sIL-2R levels were elevated in all subgroups of clinically active patients compared to controls (p less than or equal to 0.0005). Three of the 4 patients with serial sIL-2R measurements showed falling values during the period of clinical remission. Using regression analysis and likelihood ratio tests, we found a significant correlation between sIL-2R levels and both disease activity and joint count (p less than or equal to 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis, Rheumatoid↗
PubMed1991

Studies of human leprosy lesions in situ using suction-induced blisters: cell changes with IgM antibody to PGL-1 and interleukin-2 receptor in clinical subgroups of erythema nodosum leprosum.

To examine the immunopathogenesis of type 2 erythema nodosum leprosum (ENL) reactions in leprosy, we studied cellular and soluble immunologic components of skin lesions in 57 patients with reactions (19 acute ENL and 38 chronic ENL), 61 active patients without reactions, and 33 control patients whose leprosy had been treated and cured. Cells, IgM antibody to PGL-1 and Tac peptide levels were obtained from fluid aspirated from blisters induced by suction directly over representative skin lesions. During ENL reactions: a) the lesions in chronic ENL showed a decreased number of CD8+ (T-suppressor) cells and increased helper/suppressor ratio as compared to those in acute ENL and non-reactional leprosy; b) Tac peptide and IgM antibody to PGL-1 levels were elevated in the chronic ENL lesions; c) and systemic administration of corticosteroids appeared to cause a reduction in the intralesional CD4+ cell population and IgM antibody to PGL-1 but did not change CD8+ cell population and the levels of Tac peptide in the lesions. The elevated levels of Tac peptide were localized in the skin lesions while increased levels of IgM anti-PGL-1 seemed to be filtered from the peripheral blood. We conclude that spontaneous lymphocyte activation in situ, primarily of decreased CD8+ and relatively increased CD4+ cells, are important features of chronic, recurrent ENL reactions and may be an intermittent or cyclic phenomenon during the reaction. Understanding the mechanisms of these spontaneous changes in immunity in leprosy will enlarge our knowledge of reactions and of the underlying determinants of delayed type hypersensitivity and cell-mediated immunity in leprosy, which in turn will allow us to realize the potential for artificially manipulating these responses as proposed with vaccines or immunotherapy.

Adolescent↗
PubMed1991

Intrinsic activity of enantiomers of 8-hydroxy-2-(di-n-propylamino)tetralin and its analogs at 5-hydroxytryptamine1A receptors that are negatively coupled to adenylate cyclase.

Although many different types of compounds have been tested for 5-hydroxytryptamine1A (5-HT1A) binding affinity, much remains to be learned about the structural requirements associated with 5-HT1A agonism, partial agonism, and antagonism. The present study uses the forskolin-stimulated adenylate cyclase (FSC) assay as a functional screen in rat hippocampal membranes to examine structure-activity relationships for a series of enantiomers of novel analogs of the prototypic 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). The findings illustrate that there can be large enantiomeric differences in intrinsic activity at the 5-HT1A receptor, independent of enantiomeric effects on binding affinity. Generally, for each enantiomeric pair exhibiting stereoselective 5-HT1A binding, the enantiomer with the higher affinity also displayed the greater amount of 5-HT1A intrinsic activity in the FSC assay. Interestingly, the enantiomers of 8-OH-DPAT itself displayed stereoselective differences in intrinsic activity but not 5-HT1A affinity. Several of the compounds, namely (S)-UH-301, (2R,3R)-CM-12, and (1S,2R)-LEA-146, may have potential as prototypes for selective 5-HT1A antagonists, and (S)-UH-301 itself may be useful as a selective 5-HT1A antagonist. The FSC data presented here are in good agreement with reported measures of in vivo 5-HT1A activity, which were in part the basis of a recently proposed model for the 5-HT1A pharmacophore [J. Med. Chem. 34: 497-510 (1991)].

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1990

The soluble interleukin-2 receptor: biology, function, and clinical application.

PURPOSE: To review the biologic origin, functional characteristics, and current and potential clinical applications of a novel marker of immune system activation, the soluble interleukin-2 receptor (sIL-2R). DATA IDENTIFICATION: Studies reported since 1985 were identified by a computer search using MEDLINE as well as from bibliographies of published work. STUDY SELECTION: Sixty-two reports on the clinical applications of the sIL-2R, largely from peer-reviewed journals, were identified. These reports address the utility and significance of sIL-2R measurements in various conditions. Basic scientific investigations delineating the biochemical and molecular features of the human interleukin-2 receptor complex and the sIL-2R protein were reviewed. DATA EXTRACTION: The validity of sIL-2R quantitation as an index of in-vivo immune system activation and its usefulness as a measure of disease activity and outcome were examined. RESULTS OF DATA ANALYSIS: The quantitation of sIL-2R, a novel laboratory measure of in-vivo immune system activation, correlates reliably with disease activity in autoimmune inflammatory disorders, transplantation rejection, and specific infectious disorders. Markedly elevated serum sIL-2R levels are a particularly prominent feature of certain hematologic malignancies, such as human T lymphotropic retrovirus type I-associated adult T-cell leukemia and hairy cell leukemia, reflecting tumor burden and response to therapy. The sIL-2R level at disease onset may also reliably predict long-term prognosis in non-Hodgkin lymphoma, and it appears to provide an additional serologic measure in the assessment of clinical progression in patients with human immunodeficiency virus infection and the acquired immunodeficiency syndrome. CONCLUSIONS: Studies have suggested that sIL-2R levels offer a rapid, reliable, and noninvasive measure of disease activity, response to therapy, and, in some cases, prognosis in a broad spectrum of conditions associated with T- or B-cell immune activation.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Direct cloning of human transcripts with HnRNA from hybrid cell lines.

A library of human-derived complementary DNA from a human-hamster hybrid cell line containing the Xq24-qter region has been constructed. Complementary DNA synthesis was primed from heterogeneous nuclear (hn) RNA by oligonucleotides derived from conserved regions of human Alu repeats. At least 80% of these cloned sequences were of human origin, providing an enrichment of at least two orders of magnitude. Two clones, one containing a fragment of the primary transcript of the human hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene at Xq26 and another recognizing a family of human genes mapping to two regions of Xq24-qter, were characterized. Additional hncDNA clones mapped to a variety of sites in the Xq24-qter region, demonstrating the isolation of many transcriptionally active loci. These clones provide probes for identification of genetic loci on the terminal region of the X chromosome long arm, which is the location of a number of inherited disorders.

Animals↗
PubMed1990

Selective elimination in vitro of alloresponsive T cells to human transplantation antigens by toxin or radionuclide conjugated anti-IL-2 receptor (Tac) monoclonal antibody.

The human allogeneic mixed lymphocyte reaction is the in vitro correlate of graft rejection. Cytotoxic effector cells generated during an allogeneic mixed lymphocyte reaction were previously shown to express the human p55 IL-2 receptor subunit, whereas resting cells do not express this receptor peptide. In this study, we asked whether Pseudomonas exotoxin or bismuth-212 (an alpha-particle emitting radionuclide) coupled to the anti-IL-2 receptor mAb, anti-Tac, were able to selectively eliminate alloresponsive cells generated during an allogeneic mixed lymphocyte reaction. After assembly, anti-Tac immunoconjugates retained their binding integrity, specificity, and selectivity. Deletion of alloresponsive cells was shown by the removal of alloproliferating cells as assessed by quantitating cell recovery and by measurement of thymidine incorporation into newly synthesized DNA. Both toxin and radionuclide immunoconjugates eliminated established cytotoxic effector cells generated in an allogeneic mixed lymphocyte reaction, while leaving intact the PHA-inducible mitogenic response of the nonactivated cells. The addition of excess anti-Tac blocked all of the effects of these cytotoxic reagents. The therapeutic reagents in vitro were most effective when added just prior to the peak of the alloproliferative response, when receptor expression would be close to maximum. Thus, anti-Tac conjugated either with toxin or radionuclide is effective in vitro in specifically eliminating cytotoxic effector cells.

ADP Ribose Transferases↗
PubMed1990

Immunomodulatory properties and toxicity of interleukin 2 in patients with cancer.

We performed a phase Ia/Ib study of interleukin 2 (IL2) in patients with cancer. Single doses of IL2 from 10(3) units/m2 to 10(7) units/m2 were well tolerated but failed to induce significant immunological changes. Chronic IL2 treatment for 5 days out of 7 for 3 weeks was well tolerated at doses below 10(7) units/m2 and was accompanied by significant immunological changes. Following chronic treatment with intramuscular injections of IL2 at 1 x 10(6) units/m2, we observed augmentation of peripheral blood natural killer activity and induction of peripheral blood LAK activity. Induction of LAK activity was most evident when IL2 was included in the cytotoxicity assay. There was a marked increase in the number of peripheral blood mononuclear cells bearing the Leu-19 marker in association with the observed increases in natural killer and LAK activity. A small percentage of Leu-19+ cells coexpressed CD3. There was heterogeneous expression of the low affinity Fc receptor (CD16). In vivo induced Leu-19+ cells could be divided into two populations, dim and bright, based on the intensity of fluorescent staining with antibodies to Leu-19. The majority of Leu-19 bright cells were CD16- while the majority of Leu-19 dim cells were CD16+. In addition, the intensity of CD16 staining was higher for Leu-19 dim cells than for Leu-19 bright cells. Increases in the amounts of CD38 and CD8 antigens were also observed. Significant increases in serum levels of the soluble IL2 receptor were observed during treatment. One partial remission was noted in a woman with non-Hodgkin's lymphoma.

Cell Line↗
PubMed1990

The cloning and sequence analysis of the rat serotonin-1A receptor gene.

Using a probe derived from the human 5-HT1A receptor gene (G-21), a strongly hybridizable clone was identified from a rat genomic DNA library. This clone (G21Y2) had an overall deduced amino acid sequence that was 88% homologous with that of the human 5-HT1A receptor. There was only an 18% and 19% amino acid homology with the rat 5-HT1C and 5-HT2 receptors, respectively. The G21Y2 appears to be an excellent candidate for the rat 5-HT1A receptor gene. As this manuscript was being prepared a report by Albert et al. (13) was published in which a probe to the hamster beta 2-adrenergic receptor was used to identify a rat genomic (Clone D) that demonstrated a sequence that was similar to G21Y2.

Amino Acid Sequence↗
PubMed1990

Current methods for YAC clone characterization.

Yeast artificial chromosome (YAC) cloning has allowed isolation of much longer DNA fragments than was previously possible. While this technology makes feasible the isolation of large regions of complex genomes in overlapping cloned segments, it has also required altered methods for manipulation of cloned DNAs. In particular, the isolation of insert sequences from YAC clones has been especially difficult. Methods for characterization of YAC inserts are described and compared.

Chromosomes, Fungal↗
PubMed1990

Rapid isolation of DNA probes within specific chromosome regions by interspersed repetitive sequence polymerase chain reaction.

A method was recently developed for the specific amplification of human DNA sequences from interspecific somatic cell hybrids by the polymerase chain reaction (PCR) using primers directed to Alu, a short interspersed repeat element (SINE). We now show human-specific amplification using a primer to the 3' end of the human long interspersed repeat element L1Hs (LINE). A monochromosomal hybrid containing an intact human X chromosome yielded approximately 25 discrete products, ranging in size from 800 to 4500 bp. Combination of a single Alu primer and the L1Hs primer yielded a large number of smaller products (300-1000 bp) distinct from those observed with either primer alone. Inspection of ethidium bromide-stained gels showed one Alu-Alu and three Alu-L1Hs products which were present in an intact X chromosome but absent in a hybrid containing an X chromosome deleted for the single metaphase band q28. These four fragments were isolated from the gel and used as probes on Southern blots which confirmed their localization to Xq28. These results demonstrate that primers can be constructed to a variety of interspersed repetitive sequences (IRS) and used individually or in combination for the rapid isolation of DNA fragments from defined chromosomal regions by IRS-PCR.

Animals↗
PubMed1990

The molecular basis for the generation of the human soluble interleukin 2 receptor.

Using an enzyme-linked immunosorbent assay (ELISA) employing two monoclonal antibodies recognizing distinct epitopes on the interleukin 2 receptor (IL2R) alpha chain (Tac molecule), we previously demonstrated that activated lymphocytes release a soluble interleukin 2 receptor molecule (sIL2R) in vitro and in vivo. The sIL2R is biochemically and structurally related to Tac, but its precise origin and functional role remain to be defined. We report here that a single IL2R cDNA is sufficient to direct the synthesis of both cell-associated and soluble released IL2R molecules. Northern analysis of IL2R cDNA transfected L-cell lines revealed the presence of mRNA species unaccounted for by known transcription termination or internal splice sites. Nevertheless, S1 nuclease digestion studies failed to detect alternately spliced mRNA transcripts that specifically lack transmembrane or cytoplasmic domains and which may encode a secreted IL2R molecule. Therefore sIL2R does not appear to be the product of a unique post-transcriptional splicing event. In the absence of any post-translational modifications, sIL2R is most likely generated by enzymatic cleavage and release of cell surface Tac. This proteolytic release of Tac may be but one example of a common cellular mechanism for regulating the membrane expression of cell surface molecules.

Animals↗
PubMed1990

Cellular source of soluble interleukin 2 receptors in serum of mice after recombinant interleukin 2 administration.

Previous studies have shown that peripheral blood mononuclear cells activated in vitro not only express cell-associated interleukin 2 receptors (IL2R) but also release a soluble form of this receptor. In this study, we demonstrate that administration of human recombinant IL 2 (rIL 2) to mice results in increased spleen weights, splenic natural killer (NK) cell cytolytic activity, and serum levels of soluble IL2R. However, compared with rIL 2-treated heterozygote controls, beige mice treated with rIL 2 displayed similar elevations in serum soluble IL2R but significantly less splenic NK activity. Likewise, administration of anti-asialo GM1 antiserum to rIL 2-treated mice resulted in a dramatic reduction in splenic NK cytolytic activity, but no reduction in serum soluble IL2R. Conversely, while rIL 2 treatment of BALB/c mice produced increased splenic NK activity and serum soluble IL2R, similar treatment of BALB/c nude mice resulted in elevation of only splenic NK activity. These studies demonstrate that administration of rIL 2 to normal mice can elevate both serum IL2R levels and splenic NK cytolytic activity. However, the results suggest that T cells are likely to be the source of elevated serum IL2R after rIL 2 administration.

Animals↗