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Biomedical subjects

D L Nelson

Publications and source records attributed to D L Nelson.

At least 469 records · Page 26Linked to original sources
PubMed1981

In vitro production of anti-influenza virus antibody after intranasal inoculation with cold-adapted influenza virus.

We have studied the production of anti-influenza virus antibody in vitro by peripheral blood mononuclear cells (PBMC) obtained from 7 normal volunteers at various times after intranasal inoculation with cold-adapted A/Alaska/6/77 [H3N2] influenza virus. Antibody released into culture supernatants was assayed by a 2-step enzyme-linked immunosorbent assay (ELISA). Cells obtained 6 days after intranasal inoculation spontaneously released both IgG and IgA anti-influenza antibody; this antibody production occurred within 24 hr, was specific for the virus used to inoculate the volunteers, and was inhibitable by cycloheximide. When day 6 cells were cultured in vitro for 12 days with the polyclonal activator pokeweed mitogen (PWM), no increase in the amount of antibody above that released in the absence of PWM was seen. In contrast, cells obtained 27 days after inoculation made no spontaneous antibody. In addition, cultures of these day 27 cells with PWM resulted in the production of large amounts of IgG antibody but relatively little IgA anti-virus antibody. Thus, after a mucosal influenza virus infection, several subpopulations of functionally different cells sequentially appear in the peripheral circulation: an initial population of cells secreting IgG and IgA antibody spontaneously, followed by a 2nd population of cells secreting IgG antibody when stimulated with PWM.

Administration, Intranasal↗
PubMed1980

Extra prompts versus no extra prompts in self-care training of autistic children and adolescents.

A color-coded "extra prompt" procedure was compared to a "no extra prompt" procedure in teaching autistic children and adolescents how to lace shoes. One randomly assigned group of 10 autistic subjects first learned to lace shoes whose laces and eyelets were color-coded red and white, and then encountered the no extra prompt condition in which color codes could no longer be depended upon to solve the position discriminations required to lace properly. In a counterbalanced fashion, the other group of 10 autistic subjects reached criterion on the non-color-coded, naturalistic shoe before experiencing the extra prompt condition. Analysis of variance and post-hoc analyses suggest that subjects who first learned under the color-coded, extra prompt condition encountered significant difficulty in transferring their newly acquired skill to the naturalistic, non-color-coded condition, whereas subjects who learned initially without the extra prompts had little difficulty with the subsequent color-coded condition. A follow-up procedure requiring all subjects to choose between the color prompt and the position cue revealed that 11 of 20 subjects consistently chose the color cue, even though it resulted in improper lacing. It is recommended that clinicians avoid the use of highly salient, non-criterion-related prompts in teaching certain types of adaptive skills to autistic children.

Activities of Daily Living↗
PubMed1980

Biochemical studies of the excitable membrane of Paramecium. IV. Protein kinase activities of cilia and ciliary membrane.

Two protein kinases (ATP: protein phosphotransferase, EC 2.7.1.37) were detected in disrupted cilia of Paramecium tetraurelia. One of the enzymes exhibited maximum activity at pH 6.0, required 4 mM Mg2+ for its maximum activity and was stimulated by cyclic AMP and cyclic GMP. Histone was a good exogenous protein substrate for this enzyme, but protamine sulfate was not. The other protein kinase showed a peak of activity at pH 8.0, required 10 mM Mg2+ for its maximum activity and was slightly inhibited by cyclic AMP and cyclic GMP. Protamine sulfate was a good exogenous substrate for this enzyme. The pH 8.0 activity partitioned preferentially with the axonemes, but the pH 6.0 activity was divided almost equally between the axonemes and the membranes. We also found indirect evidence for the presence in cilia of phosphoprotein phosphatase (phosphoprotein phosphohydrolase, EC 3.1.3.16) and adenyl cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) activity.

Adenosine Triphosphate↗
PubMed1980

Biochemical studies of the excitable membrane of Paramecium tetraurelia. III. Proteins of cilia and ciliary membranes.

As a first step in the biochemical analysis of membrane excitation in wild-type Paramecium and its behavioral mutants we have defined the protein composition of the ciliary membrane of wild-type cells. The techniques for the isolation of cilia and ciliary membrane vesicles were refined. Membranes of high purity and integrity were obtained without the use of detergents. The fractions were characterized by electron microscopy, and the proteins of whole cilia, axonemes, and ciliary membrane vesicles were resolved by SDS polyacrylamide gel electrophoresis and isoelectric focusing in one and two dimensions. Protein patterns and EM appearance of the fractions were highly reproducible. Over 200 polypeptides were present in isolated cilia, most of which were recovered in the axonemal fraction. Trichocysts, which were sometimes present as a minor contaminant in ciliary preparations, were composed of a very distinct set of over 30 polypeptides of mol wt 11,000--19,000. Membrane vesicles contained up to 70 polypeptides of mol wt 15,000--250,000. The major vesicle species were a high molecular weight protein (the "immobilization antigen") and a group of acidic proteins with mol wt similar to or approximately 40,000. These and several other membrane proteins were specifically decreased or totally absent in the axoneme fraction. Tubulin, the major axonemal species, occurred only in trace amounts in isolated vesicles; the same was true for Tetrahymena ciliary membranes prepared by the methods described in this paper. A protein of mol wt 31,000, pI 6.8, was virtually absent in vesicles prepared from cells in exponential growth phase, but became prominent early in stationary phase in good correlation with cellular mating reactivity. This detailed characterization will provide the basis for comparison of the ciliary proteins of wild-type and behavioral mutants and for analysis of topography and function of membrane proteins. It will also be useful in future studies of trichocysts and mating reactions.

Animals↗
PubMed1980

Characteristics of serotonin receptors in the rat brain.

Two biochemical methods are currently available for studying 5-HT receptors in the central nervous system. The first consists of measuring the specific high affinity binding of 3H-5-HT to synaptic membranes. The other derives from the discovery of an adenylate cyclase which can be activated by 5-HT in brain homogenates. Whereas the specific 3H-5-HT binding is measurable in young as well as in adult rats, the 5-HT-sensitive adenylate cyclase can be quantitatively estimated only during the first three weeks following birth. Later on, the increment of adenylate cyclase activity produced by 5-HT is too low to permit valid measurements, notably in tissues from adult rats. Studies on the effects of various agonists and antagonists demonstrated that the specific binding site characterized by a high affinity for 3H-5-HT (Kd = 1.5 nM) exhibited the expected properties of a 5-HT receptor in brain. Performing chemical lesions on serotoninergic neurons by an intracerebral injection of 5, 7-dihydroxytryptamine or the blockade of central 5-HT receptors by the peripheral administration of methiothepin resulted in a subsequent increase in the number of specific binding sites for 3H-5-HT particularly in the hippocampus (+30 to +45%). In contrast, preliminary attempts to detect any supersensitivity of the 5-HT-sensitive adenylate cyclase after selective raphe lesions were unsuccessful. Indeed, several observations strongly suggested that the high affinity binding site for 3H-5-HT did not correspond to the 5-HT receptor coupled to adenylate cyclase in synaptic membranes: 1) the apparent affinity of the 5-HT-sensitive adenylate cyclase for 5-HT was about 300 times lower (Kd = 0.5 microM) than that of the specific 3H-5-HT binding site; 2)the ontogenic evolutions of 3H-5-HT binding and 5-HT-sensitive adenylate cyclase were not parallel, notably in the hippocampus; 3) they were differently affected by several drugs. For instance, quipazine, a putative 5-HT agonist, effectively displaced 3H-5-HT from its specific binding site (Ki = 0.23 microM) whereas it did not affect 5-HT-sensitive adenylate cyclase. In conclusion, it is likely that the high affinity binding site for 3H-5-HT and the 5-HT-sensitive adenylate cyclase belong to two different postsynaptic 5-HT receptors in the rat brain.

Adenylyl Cyclases↗
PubMed1980

Gluten-sensitive enteropathy. Influence of histocompatibility type on gluten sensitivity in vitro.

We previously developed an in vitro organ culture system in which gluten exerts a toxic effect on intestinal mucosa of patients with active gluten-sensitive enteropathy. Gluten generally inhibits the epithelial cell maturation of intestinal biopsy specimens that otherwise occurs if the tissue is cultured for 24-48 h in a gluten-free medium. However, small intestinal mucosa from 15-20% of patients with proven gluten-sensitive enteropathy fails to manifest the expected gluten-induced damage in vitro. In the present study, we explored the relation between in vitro gluten-induced intestinal damage and the presence of HLA-B8. We determined whether the patients' histocompatibility type (HLA-B8 positive or negative) influenced the ability of gluten protein to inhibit epithelial cell maturation of cultured intestinal biopsy specimens from patients with gluten-sensitive enteropathy. Intestinal biopsies from 21 of 24 patients with gluten-sensitive enteropathy and HLA-B8 showed gluten-induced damage in vitro. On the other hand, intestinal biopsies from only 4 of 16 patients with gluten-sensitive enteropathy but without HLA-B8 showed gluten-induced damage in vitro. The difference in the effect of gluten in vitro between these two groups was statistically significant (P < 0.01). The data show a dichotomy between gluten-induced tissue damage in vivo and in vitro in HLA-B8 negative patients, suggesting that HLA-B8 is important for gluten to manifest a cytotoxic influence in organ culture.

Alkaline Phosphatase↗
PubMed1980

Encoding and cuing sounds and senses.

These experiments address the issue of how retrieval cues operate, and they focus on two problems of cuing research. The first concerns attempts to determine the useful limits of information residing in the cues themselves. Retrieval cues may be effective only because they provide direct information about the encoded trace or, alternatively, because they can be used to reconstruct encoded information outside of their immediate domains. The second problem concerns the nature of contextual cues appearing on the study trial and their relationship to what is encoded of spreading activation occurring on this trial. In these experiments, semantic and sensory set sizes of the target words were varied with recall cued by either the endings of the targets or by associatively related words. The targets were encoded without specific contextual cues, in the presence of associatively related context cues, or, finally, in the presence of rhyme-related context cues. The results suggest that retrieved information extends beyond the domain of features inherent in the test cue and that what is encoded in the study-trial activation is dependent on the nature of the context.

Association Learning↗
PubMed1979

Tetracaine blocks the responses of isolated acinar cells from rat parotid to carbachol but not to substance P.

Carbachol and substance P stimulated 45Ca2+ flux changes, 86Rb+ efflux, and amylase secretion from acinar cells isolated from rat parotid. The local anesthetic tetracaine blocked all of these measured responses to carbachol, but none of the responses to substance P. Tetracaine must act at either the cholinergic receptor or at a subsequent transducing step in the cholinergic stimulus-response sequence. If tetracaine acts at one of the transducing steps between cholinergic receptor occupation and the physiological responses then the action of tetracaine must be at a locus in the cholinergic reaction scheme not shared by substance P, because tetracaine did not block any response of the parotid to substance P.

Amylases↗
PubMed1979

Biochemical studies of the excitable membrane of Paramecium tetraurelia. II. Phospholipids of ciliary and other membranes.

The phospholipids of cilia and deciliated bodies of Paramecium tetraurelia were isolated and characterized. 1-alkyl-2-acyl-sn-glycero-3-(2'-aminoethyl) phosphonate (GAEPL), phosphatidylethanolamine, and 1-alkyl-2-acyl-sn-glycero-3-phosphorylcholine (GPC) were the major lipids of Paramecium, and the minor lipids included phosphatidylinositol, cardiolipin, ceramide-(2-aminoethyl) phosphonate (CAEP), ceramide phosphorylethanolamine (COPE) and four sphingolipids whose identity was not established. The deciliated bodies contained 4% cardiolipin, 15% GAEPL, 41% phosphatidylethanolamine, 30% GPC and 3% each of CAEP and phosphatidylinositol; the cilia contained no cardiolipin, 24% GAEPL, 37% phosphatidylethanolamine, 15% GPC, 15% CAEP, 3% phosphatidylinositol, 2% COPE and small amounts (approx. 1%) of the four uncharacterized sphingolipids. No alteration in phospholipid composition was found among cells harvested in the various stages of growth. The phospholipids of six Paramecium mutants of three distinct phenotypes (pawn, paranoiac and fast) were also examined. Only one significant difference was found on comparison of the whole cell, deciliated body and cilia fraction of the mutants with the analogous fractions from wild type cells: the fast mutant, fA 97, had two extra, minor phospholipids (approx. 2%) in the deciliated body fraction that were tentatively identified as 1,2-diacyl-sn-glycero-3-(2'-aminoethyl) phosphonate (AEPL) and 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamine (GPE).

Animals↗
PubMed1979

In vitro and in vivo disposition of 3H-methiothepin in brain tissues. Relationship to the effects of acute treatment with methiothepin on central serotoninergic receptors.

A single treatment with a large dose of methiothepin (20 mg/kg, i.p.) induced, as early as the 2nd day after injection, a significant increase (+20--35%) in the number of specific binding sites for 3H-5-HT in forebrain areas, particularly the hippocampus. Experiments with 3H-methiothepin indicated that the drug remained firmly bound to brain membranes thus maintaining a local concentration high enough to effectively block 5-HT receptors for 10--12 h after its peripheral administration. Accordingly, it can be concluded that the occupancy of central 5-HT receptor sites by methiothepin for several hours was sufficient to induce a supersensitivity phenomenon within the two following days. Although 3H-methiothepin was a useful marker for analyzing the disposition and the kinetics of the 5-HT antagonist in brain tissues, it could not be used as a specific ligand of 5-HT receptors in brain since under in vitro as well as in vivo conditions most of 3H-methiothepin bound to non-specific sites, especially to the lipid component of the membranes.

Adenylyl Cyclases↗
PubMed1979

Fluorescent probes for asymmetric lipid bilayers: synthesis and properties in phosphatidyl choline liposomes and erythrocyte membranes.

We have synthesized three sets of fluorescent probes which we believe will be useful in studies of asymmetric membranes and have studied their interactions with model lipid bilayers and erythrocyte membranes. The probes were designed to partition preferentially into one face of a lipid bilayer with asymmetrically disposed phospholipids and to report lipid transitions in that monolayer. We synthesized more than twenty probes containing anthroyl-, dansyl-, or pyrene rings with acidic, basic, and neutral functional groups and alkyl "spacers" of various lengths. The interactions of these probes with liposomes of phosphatidyl choline and with erythrocyte membranes were characterized to determine whether probe insertion was asymmetric, how deeply the probe penetrated the bilayer, and whether the probe reflected thermotropic phase transitions in model membranes. The set of variously charged anthroyl esters, analogs of local anaesthetics, appears to be promising for studies of asymmetric membranes. Fluorescent probes have been used extensively to provide information on the lipid regions of biological membranes. Membrane fluidity, a composite of molecular packing and motion of acyl chains in lipid bilayers, has been assessed with a variety of fluorescent probes, the fluorescence of which undergoes some measurable change at the temperature of the membrane's thermotropic phase transition. A large number of fluorescent probes have been used for this purpose. Bashford, Morgan and Radda (Bashford, C.L., Morgan, C.G., Radda, G.K. 1976; Biochim. Biophys. Acta 426:157) and Thulborn and Sawyer (Thulborn, K.R., Sawyer, W. H. 1978; Biochim. Biophys. Acta 511:125) synthesized several fatty acid derivatives in which an anthracene group is attached (in ester linkage) along the acyl chain at various positions, and have shown that this set of probes may be useful in probing membrane fluidity at different depths within the bilayer. This report describes the synthesis and properties of several sets of amphipathic fluorescent probes, which may partition unequally into the two faces of an asymmetric lipid bilayer, and may therefore provide information about membranes complementary to that obtainable with existing probes.

Animals↗
PubMed1979

Cyanide residue levels in extracted honey, comb honey and wax cappings.

Cyanide (CN) residue levels were determined in samples of extracted honey, comb honey and was cappings at 1 hr, 24 hr, and 48 hr intervals after destroying the bees in honey bee colonies with normal (ca. 8.5 g) and twice normal (ca. 17 g) doses of CyanogasR A-dust. Applications of CyanogasR A-dust, administered by means of a dust pump at normal and twice normal doses, gave an average residue of 0.01 and 0.04 microgram CN/g of extracted honey, 0.01 and 0.02 microgram CN/g of comb honey and 0.04 and 0.06 microgram CN/g of wax cappings, respectively. When the CyanogasR A-dust (ca. 17 g) was placed on a tray and placed on the bottom board of the hive, the average residue levels for extracted honey, comb honey and wax cappings were less than 0.004, 0.01 and 0.02 microgram CN/g, respectively. Random honey samples from beekeepers, who used CyanogasR to destroy bees, had a median level of 0.031 microgram CN/g, whereas honey from a packing plant and other commercial samples contained less than 0.004--0.026, median less than 0.004 microgram CN/g. Based on residue data from this study, the temporary registration for CyanogasR, to kill honey bees after crop removal, was revised to a full registration in May 1977.

Bees↗