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Biomedical subjects

D L Nelson

Publications and source records attributed to D L Nelson.

At least 451 records · Page 25Linked to original sources
PubMed1982

Identification of factors of affective meaning in four selected activities.

The premise that activities have inherent meanings is basic to the theory and practice of occupational therapy. In this study the investigators hypothesized that different activities would elicit different kinds of affective meanings in their participants. The subjects in this study were 59 students beginning their training in occupational therapy. On their first day in an activities class, and before instruction in activity analysis, the subjects were presented with four selected activities. Immediately after performing each activity, the students were requested to rate the activity according to Osgood's 12-scale short-form semantic differential. The data generated were reduced subsequently to Osgood's three factors of affective meaning: "evaluation," power," and "activity" (in this study called action). Results indicated that the four activities elicited significantly different responses on all three factors. Specific results and implications of this study's methodology for future occupational therapy research are discussed.

Adult↗
PubMed1982

Production of human suppressor T cell hybridomas.

To study human T cell suppression of immunoglobulin (Ig) synthesis with homogeneous populations of immunoregulatory cells, human suppressor T cell hybridomas were prepared by somatic cell fusion of concanavalin A-activated peripheral blood T cells with hypoxanthine-guanine phosphoribosyltransferase-(HGPRT, EC 2.4.2.8) deficient human leukemic CEM T cells. After selection in hypoxanthine-aminopterin-thymidine (HAT) medium and cloning by limiting cell dilution, two human T cell hybridomas were identified that produced 60 to 80% suppression of in vitro polyclonal immunoglobulin production when cocultured with pokeweed mitogen- (PWM) stimulated peripheral blood lymphocytes. Further, one of the suppressor T cell hybridomas constitutively secreted a soluble suppressor factor(s) (TsF) of m.w. 70,000 to 85,000 daltons, which produced reversible noncytotoxic inhibition of lectin-activated B cell Ig production. In contrast, this TsF did not inhibit lectin- or antigen-induced T cell proliferation, nor did it interfere with the generation or effector function of cytotoxic T cells. Additional studies indicated that this Tsf acts directly on B cells or monocytes rather than indirectly modulating the activity of immunoregulatory T cells. In summary, these studies suggest that techniques of somatic cell fusion may provide a valuable approach to further study human immunoregulatory cell-cell interactions as well as provide a source of sufficient quantities of important lymphokines for further purification and characterization.

Cell Division↗
PubMed1982

Immunologic characteristics of intestinal lymphoid cells of the guinea pig.

Populations of lymphoid cells from the gastrointestinal tract of guinea pigs were compared with splenic cells for both morphologic and functional characteristics. Gastrointestinal lymphoid cells were isolated from mesenteric lymph nodes, Peyer's patches, and also for the epithelium and lamina propria of the small intestinal mucosa. Isolated intraepithelial and lamina propria lymphocyte populations contained (a) T cells, B cells, and macrophages; (b) T cells that proliferated to phytohemagglutinin and concanavalin A; and (c) B cells that proliferated to bacterial lipopolysaccharide. Using inbred guinea pigs, the intraepithelial and lamina propria lymphocytes were shown to contain T cells capable of proliferating to alloantigens in mixed leukocyte culture, and also cells capable of stimulating alloreactive T cells. These studies demonstrate the presence of immunologically reactive T cells and B cells in isolated small intestinal mucosal lymphoid cells from guinea pigs.

Animals↗
PubMed1982

Developmental trends in the phonemic organization of individual words.

Research with adults indicates that the visual-phonemic representation linked to individual words has a characteristic organization. This structure conforms to a serial pattern, with word beginnings functionally more important than word endings, which, in turn, are functionally more important than word middles. The present experiments were designed to identify possible developmental trends in this organization. The results of two experiments indicated that the adult pattern is apparent for nonreading first graders, but only if the words being learned are monosyllabic. Going grade by grade, the typical adult pattern for bisyllabic words did not emerge clearly until the fifth grade. These findings suggest that the serial organization for individual words is established before children learn to read, and that the pattern emerges for more complex words when they become integrated into more holistic units.

Adolescent↗
PubMed1981

Characterization of a soluble suppressor of human B cell immunoglobulin biosynthesis produced by a continuous human suppressor T cell line.

A human suppressor T cell maintained in long-term culture with conditioned medium containing interleukin 2 elaborates a suppressor factor(s) that specifically inhibits human polyclonal B cell immunoglobulin biosynthesis. This soluble immune suppressor supernate of immunoglobulin production (CTC-SISS-B) shares a number of features with the previously described suppressive mediator elaborated by concanavalin A-activated human peripheral T cells (SISS-B) including: (a) the inhibition by a noncytotoxic mechanism, (b) the suppression of immunoglobulin biosynthesis either through direct action on the B cell or indirect action via the monocyte, (c) the loss of inhibition in the presence of the monosaccharide L-rhamnose, (d) the elaboration by cells irradiated with 500 ro 2,000 rad, and (e) molecular weights of 60,000--90,000. Furthermore, the suppression by this mediator appears to be specific for B cell immunoglobulin production in that CTC-SISS B has no effect on T cell proliferation to mitogens, antigens, an allogeneic cells or on T cell-mediated cytotoxicity. These data indicate that one possible mechanism of suppressor T cell inhibition of human immunoglobulin production is via the generation of a lectinlike suppressor lymphokine that interacts with defined saccharide determinants on the cell surface of either the B cell or monocyte.

Animals↗
PubMed1981

Improved purification and some properties of megacin Cx, a bacteriocin produced by Bacillus megaterium.

Megacin Cx is a bacteriocidal protein, previously described by Durner and Mach (Durner, K. (1970) Z. Allg. Mikrobiol. 10, 93-102; Durner, K. (1970) Z. Allg. Mikrobiol. 10, 373-382; Durner, K., and Mach, F. (1966) Zentralbl. Bakteriol. Parasitenkd. Infektionskr. Hyg. Abt. I Orig. 2, 120, 565-575), which is released into the medium during growth by Bacillus megaterium strain 337. We have optimized the culturing conditions to achieve reproducibly high yields of this protein; under these conditions, megacin Cx represents about one-half of the protein secreted into the medium. We have developed improved methods of purifying the protein to homogeneity. The active form of megacin Cx is a monomeric protein, a single polypeptide of Mr = 210,000, as determined by analytical ultracentrifugation and gel electrophoresis in sodium dodecyl sulfate. Like many other proteins secreted by Gram-positive organisms, megacin Cx contains remarkably little methionine and cysteine. The purified protein blocks protein synthesis in sensitive cells, but has little immediate effect upon nucleic acid synthesis. Our purification procedure separates megacin Cx from another activity in the culture medium which blocks the synthesis of RNA and DNA, as well as synthesis of protein, in sensitive cells.

Amino Acids↗
PubMed1981

Ehlers-Danlos syndrome type VIII.

The Ehlers-Danlos syndrome (EDS) is a group of inherited disorders of connective tissue characterized by joint hypermobility, cutaneous hyperextensibility, and tissue fragility. At least nine subgroups of the disease have been described, each with a characteristic clinical pattern or unique biochemical defect. We describe three members of a family with the constellation of findings diagnostic of EDS type VIII. The trait first manifests in childhood, when minor trauma produces ecchymoses, which resolve normally except on th shins. The pretibial skin heals with distinct hyperpigmented atrophic scars. There is no hyperextensibility of the skin, nor evidence of visceral involvement. Minimal joint hypermobility was noted in one patient. Early onset of periodontal disease, with loss of the permanent teeth, is characteristic. EDS type VIII is inherited as an autosomal dominant trait.

Adolescent↗
PubMed1981

Biochemical studies of the excitable membrane of Paramecium tetraurelia VI. Endogenous protein substrates for in vitro and in vivo phosphorylation in cilia and ciliary membranes.

The endogenous protein kinases of isolated Paramecium tetraurelia cilia phosphorylated approximately 30 ciliary polypeptides in vitro. Labeling with [gamma-32P]ATP was not proportional to the amount of each protein in cilia; some minor polypeptides (e.g., 67,000 and 180,000 mol wt) were more heavily labeled than some major polypeptides. Certain of the endogenous substrates for protein kinase were localized in the ciliary membrane (130,000, 86,000, 67,000, and 45,000 mol wt); others were found in axonemes or in both fractions. With cilia from bacterized cultures in the undefined Cerophyl medium, the labeling of specific endogenous phosphate acceptors was altered by pH, cyclic AMP, and cyclic GMP, but the labeling pattern was not affected by the presence of Na+ or K+ (15 mM), Ba++ (5 mM), Ca++ (10(-5) or 10(-4) M), or EGTA. Very similar results were obtained with cilia from cells grown axenically in a semidefined medium; the molecular weights and the extent of phosphorylation of the phosphopolypeptides were comparable to those of cilia from bacterized Cerophyl cultures, although no significant cyclic nucleotide effects were observed in the axenic cilia. Most of the phosphopolypeptides labeled in vitro also turned over rapidly in vitro. The phosphoprotein phosphatase responsible for turnover was partially inhibited by 5 mM NaF. The pattern of ciliary polypeptides labeled in vivo was similar to that observed in the in vitro experiments, although the relative intensities of labeling differed. Six behavioral mutants of Paramecium, known to have defects in the excitable membrane that regulates the ciliary beat, showed normal patterns of ciliary protein phosphorylation in vitro, with and without added cyclic nucleotides, at both pH 6.0 and pH 8.0. The mutants also had apparently normal phosphoprotein phosphatase. The Paranoiac A mutant, however, showed a reduction in cyclic GMP-stimulated protein kinase activity.

Animals↗
PubMed1981

Calmodulin is a major component of extruded trichocysts from Paramecium tetraurelia.

Extruded trichocysts are composed of a family of proteins with molecular weights between 15,000 and 20,000. We have used heat treatment and affinity chromatography on fluphenazine-Sepharose to purify calmodulinlike proteins from whole cells and from extruded trichocysts. The purified protein from trichocysts is indistinguishable from that of whole cells; it is heat-stable, activates brain phosphodiesterase in a Ca++-dependent fashion, changes mobility on SDS polyacrylamide gels in the presence of Ca++, contains 1 mol of trimethyllysine/17 kdaltons, and has the amino acid composition characteristic of calmodulins. Calmodulin is a major component of purified, extruded trichocysts, of which it represents between 1 and 10% by mass. The other proteins of the trichocyst also resemble calmodulin in several properties. Possible roles for calmodulin in the Ca++-activated extrusion of trichocysts is discussed.

Animals↗
PubMed1981

[3H]Metergoline: a new ligand of serotonin receptors in the rat brain.

A specific binding site for [3H]metergoline characterized by a KD of 0.5-1.0 nM was detected in microsomal and synaptic plasma membranes from various areas of the adult rat brain. Experiments with 5,7-dihydroxytryptamine- and kainic acid-induced lesions indicated that this specific binding site was localized post-synaptically with respect to serotoninergic neurons. The pharmacological characteristics of [3H]metergoline binding to microsomal membranes from the whole forebrain strongly suggest that this ligand labels a class of serotonin receptors. This was particularly obvious in the hippocampus in which serotonin was about 400 times more potent than dopamine and noradrenaline for displacing bound [3H]metergoline. In the striatum, serotonin was only 10 times as potent as dopamine in inhibiting [3H]metergoline binding, suggesting that this ligand may also bind to dopamine receptors. Striking similarities between the binding sites for [3H]metergoline and [3H]serotonin were observed in the hippocampus. Thus, not only the total numbers of binding sites for these two ligands in control rats but also their respective increases following intracerebral 5,7-dihydroxytryptamine treatment were very similar. Therefore, at least in the hippocampus, [3H]metergoline might well be the appropriate ligand for studying the characteristics of the 'antagonist form' of serotonin receptors postulated by Bennett and Snyder.

5,7-Dihydroxytryptamine↗
PubMed1981

Discrimination of multiple [3H]5-hydroxytryptamine binding sites by the neuroleptic spiperone in rat brain.

Certain neuroleptic drugs, such as spiperone and (+) butaclamol, can discriminate between two populations of [3H]5-hydroxytryptamine ([3H]5-HT) binding sites in rat brain. The butyrophenone neuroleptic spiperone shows the greatest selectivity for these two binding sites, having at least a 3000-fold difference between its dissociation constants (2-12 nM versus 35,000 nM) for the high- and low-affinity sites, respectively. Inhibition of [3H]5-HT binding by spiperone in rat frontal cortex and corpus striatum yields distinctly biphasic inhibition curves with Hill slopes significantly less than unity. Results from nonlinear regression analysis of these inhibition studies were consistent with a two-site model in each brain region. In the frontal cortex the high-affinity neuroleptic sites comprised about 60% of the total [3H]5-HT binding sites whereas in the corpus striatum they accounted for only 20% of the sites. Furthermore, saturation studies of [3H]5-HT binding assayed in the absence or presence of 1 microM-spiperone (a concentration that completely blocks the high-affinity site while having minimal activity at the low-affinity site) reveal a parallel shift in the Scatchard plot with no change in the dissociation constant of [3H]5-HT, but a significant decrease (64% in frontal cortex or 28% in corpus striatum) in the number of specific binding sites. These observations are consistent with the existence of at least two populations of [3H]5-HT binding sites having a differential regional distribution in rat brain.

Animals↗
PubMed1981

Hemagglutinin-specific enzyme-linked immunosorbent assay for antibodies to influenza A and B viruses.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies present in human serum or nasal washes directed against influenza A or B hemagglutinin glycoproteins. The assay was modified to measure the immunoglobulin isotype specificity of the anti-hemagglutinin response in serum and nasal secretions. In the postinfection sera anti-hemagglutinin of the immunoglobulin G isotype was predominant, whereas in nasal secretions the antibody was predominantly immunoglobulin A. The antibody response detected by the ELISA manifested hemagglutinin subgroup specificity. In addition, there was a good correlation between the ELISA antibody titer and the hemagglutination-inhibition or neutralizing antibody titer. The ELISA was more sensitive than the hemagglutination-inhibition assay, and the range of antibody titers measurable by ELISA in human serum was from less than 1:20 for children who had never experienced influenza infection to 1:400,000 for adults convalescing from a secondary infection. With more sensitive tests to detect antibody to the influenza hemagglutinin it should be possible to determine the relative contribution of local and systemic immunity to resistance to influenza virus infection.

Adult↗
PubMed1981

Adult performance on the Southern California Kinesthesis and Tactile Perception Tests.

Researchers and clinicians working with various adult populations have no practical, complete, reliable, and valid method of measuring the tactile and kinesthetic functions of their clients. This study gathers preliminary normative information on the performance of adults on the Southern California Kinesthesia and Tactile Tests. Fifty-one normal men and women with a mean age of 26 years were administered the Kinesthesia, Manual Form Perception, Finger Indentification, Graphesthesia, Localization of Tactile Stimuli, and Double Tactile Stimuli Tests in the order in which they were standardized. Test-retest reliability was studied in 41 of these subjects. Results indicated that the assessment of normal adults was hampered by ceiling effects and by low reliability, but that these six tests might well serve a useful function in discriminating between relatively severe dysfunction and normal function in adults. Suggestions were made toward the development of new measurement instruments specifically designed for adults.

Adult↗
PubMed1981

Specific anti-influenza virus antibody production in vitro by human peripheral blood mononuclear cells.

Cultures of human peripheral blood mononuclear cells stimulated in vitro with influenza virus were found to produce anti-influenza virus antibody. An enzyme-linked immunosorbent assay was used to measure cumulative antibody secretion into culture supernatants. Optimal antibody production was obtained with 2 x 10(6) peripheral blood mononuclear cells cultured in flat-bottomed wells for 12 days in 2 ml of RPMI 1640 medium supplemented with 10% fetal calf serum, antibiotics, and 4 mM L-glutamine. Antibody could be detected in cultures stimulated with live A/Hong Kong/68 (H3N2), purified formalin-inactivated A/Aichi/68 (H3N2), or live B/Hong Kong/68 influenza virus. Antibody of both IgG and IgM isotypes was produced. Under optimum conditions, the secreted IgG antibody was found to be directed preferentially at antigens on the stimulating virus. Antibody production was shown to require the cooperative interaction of B and T cells. Poisson analysis of B cell precursor frequency showed that approximately 1 in 40,000 B cells could be induced to produce IgG anti-influenza virus antibody in virus-stimulated cultures. Further investigation of this in vitro response should allow dissection of the cellular mechanisms involved in the regulation of antibody production in man.

Antibodies, Viral↗
PubMed1981

Multiple 3H-5-hydroxytryptamine binding sites in rat brain.

1. The effects of spiperone on 3H-5-HT binding to membranes prepared from rat diencephalon and lower brain stem were studied for comparison with telencephalic structures. 2. The neuroleptic spiperone produced shallow, complex inhibition curves of 3H-5-HT binding in the non-telencephalic areas, suggesting the presence of different types of high-affinity 3H-5-HT binding sites. However, the shape of the curves from the non-telencephalic areas differed from those of telencephalic regions. For example, there was a tendency for low concentrations of spiperone to cause an increase in binding in the diencephalon and lower brain stem rather than a decrease as seen in telencephalic areas. 3. In a search for other compounds which, like spiperone, could discriminate between the different types of 3H-5-HT binding sites in rat telencephalon, it was found that most drugs show little difference in their affinities for the two sites. However, one compound, AHR 1709B, was found to be about 10 times more potent in rat frontal cortex than corpus striatum, indicating that it can differentially recognize the two binding sites. 4. These results are consistent with the existence of multiple types of 3H-5-HT binding sites in the rat brain, and they define regional differences that had not previously been described. In addition, a new compound which can discriminate between different types of 3H-5-HT binding sites has been found, leading the way to the study of a series of new drugs which may selectively alter serotoninergic function.

Animals↗