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Biomedical subjects

D L Nelson

Publications and source records attributed to D L Nelson.

At least 433 records · Page 24Linked to original sources
PubMed1983

Antibodies to the ciliary membrane of Paramecium tetraurelia alter membrane excitability.

Immobilization of Paramecium followed the binding of antibodies to the major proteins of the ciliary membrane (the immobilization antigens, i-antigens, approximately 250,000 mol wt). Immunoelectron microscopy showed this binding to be serotype-specific and to occur over the entire cell surface. Antibody binding also reduced the current through the Ca-channel of the excitable ciliary membrane as monitored using a voltage-clamp. The residual Ca-current appeared normal in its voltage sensitivity and kinetics. As a secondary consequence of antibody binding, the Ca-induced K-current was also reduced. The resting membrane characteristics and other activatable currents, however, were not significantly altered by the antibody treatment. Since monovalent fragments of the antibodies also reduced the current but did not immobilize the cell, the electrophysiological effects were not the secondary consequences of immobilization. Antibodies against the second most abundant family of proteins (42,000-45,000 mol wt) had similar electrophysiological effects as revealed by experiments in which the Paramecia and the serum were heterologous with respect to the i-antigen but homologous with respect to the 42,000-45,000-mol-wt proteins. Protease treatment, shown to remove the surface antigen, also caused a reduction of the Ca-inward current. The loss of the inward Ca-current does not seem to be due to a drop in the driving force for Ca++ entry since increasing the external Ca++ or reducing the internal Ca++ (through EGTA injection) did not restore the current. Here we discuss the possibilities that (a) the major proteins define the functional environment of the Ca-channel and that (b) the Ca-channel is more susceptible to certain general changes in the membrane.

Animals↗
PubMed1983

Distribution of fibronectin and laminin in basal cell epitheliomas.

The distribution of fibronectin (FN) and laminin (LM) in basal cell epithelioma was evaluated by indirect immunofluorescence. FN is a glycoprotein which promotes interaction between cells and the extracellular matrix, and is present at the dermal-epidermal junction (DEJ) and throughout the dermis, but absent in the normal epidermis. LM, a noncollagenous basement membrane protein, plays a role in epithelial adhesion to type IV collagen, and is normally present in the DEJ, but absent in the epidermis. The role of FN and LM in epithelial differentiation has not been established. Therefore, the distribution of FN and LM in a tumor of epithelial origin was studied by indirect immunofluorescence. Using affinity-purified antibodies to FN and LM, and the appropriate fluorescein-conjugated second antibodies, normal skin and 7 basal cell tumors were examined. By immunofluorescence, nests of malignant basal cells were surrounded by linear LM staining. FN immunofluorescence was intense throughout the connective tissue stroma of all tumors. Five tumors also showed FN staining within the nests of neoplastic cells, and 4 of these were also LM-positive in the tumor bulk. These immunofluorescent findings suggest that epidermal neoplasia can be associated with alterations in the distribution of FN and LM.

Basement Membrane↗
PubMed1983

Specific anti-influenza virus antibody production in vitro by lymphocytes from a subset of patients with hypogammaglobulinemia.

Specific anti-influenza virus antibody production in vitro was studied in peripheral blood mononuclear cells from 17 patients with hypogammaglobulinemia. Cells obtained from 6 of 12 patients with common variable hypogammaglobulinemia produced anti-influenza virus antibody, predominantly of the IgM isotype, when cultured in vitro with type A influenza virus. No antibody was produced in vitro, however, by cells from either of two patients with Bruton's type X-linked hypogammaglobulinemia or by cells from any of three patients with X-linked hypogammaglobulinemia and isolated growth hormone deficiency. These studies demonstrate that peripheral blood mononuclear cells from a subset of patients with common variable hypogammaglobulinemia retain the potential to produce specific antibody in response to antigenic stimulation.

Adult↗
PubMed1983

The effect of psychological type on the mood and meaning of two college activities.

This study used the Myers-Briggs Type Indicator to identify two types of college students who differed in preferred perceptual processes, with one group strongly preferring the use of sense impressions (sensing types), and the other preferring the use of unconscious associations (intuitive types) in becoming aware of phenomena. All subjects then participated in two collage activities with slightly different instructions, one requiring a creative approach and the other requiring imitation. Change in mood after each college was measured by the Bipolar Form of the Profile of Mood States, and the affective meanings of the two activities were assessed by Osgood's 12-scale short-form semantic differential. Results indicated that the creative activity elicited significantly higher scores on two mood states (agreeable-hostile and composed-anxious) and two factors of affective meaning (power and evaluation). Intuitive types rated both activities higher than sensing types on one mood (agreeable-hostile) and one factor of affective meaning (action). Hypothesized interactions were not found. The findings have possible implications for the effects of occupational therapy activities that require creativity as opposed to imitation as well as for the effects of perceptual preferences on the moods and meanings of activities.

Adult↗
PubMed1983

Decreasing drooling through techniques to facilitate mouth closure.

A single case ABA experimental design is presented in which techniques to facilitate mouth closure were hypothesized to decrease drooling. The subject was an 11-year-old male with mental retardation and cerebral palsy. Baseline 1 consisted of 10 half-hour sessions of play, followed by 1-hour periods during which the amount of saliva collected on an absorbent bib was measured and recorded. The subsequent treatment phase of 4 weeks was identical to the baseline except that a half-hour period of intervention was substituted for the half-hour of play. Intervention involved providing jaw control with intermittent tapping and jiggling, stroking the upper gum, and giving juice with jaw control. Baseline 2 consisted of 10 sessions identical to baseline 1. Results indicate that the amount of saliva leaving the mouth was a function of the presence or absence of intervention.

Cerebral Palsy↗
PubMed1983

Defective in vitro production of influenza virus-specific cytotoxic T lymphocytes in ataxia-telangiectasia.

Peripheral blood mononuclear cells (PBMC) from patients with ataxia-telangiectasia (A-T) were studied for their capacity to proliferate and to generate influenza virus-specific cytotoxic T lymphocytes (CTL) after in vitro stimulation with influenza A/Hong Kong (A/HK (H3N2)) virus. PBMC from 11 patients proliferated poorly to A/HK and 10 of the 11 patients failed to exhibit significant CTL effector activity when tested on influenza A/HK virus-infected autologous target cells. In contrast, PBMC from each of 18 simultaneously studied, unrelated normal individuals proliferated to A/HK and generated influenza-immune CTL. In each of the 10 A-T patients, deficient CTL activity was shown to be due to a lack of generation of CTL and not to target cell resistance to lysis, because the virtually infected target cells of the patients were lysed by parental influenza-immune CTL. Determinations of T cell numbers and existing serum antibody titers to H3N2 influenza virus suggest this nonresponsiveness cannot be simply explained by a lack of T cells or the absence of exposure to type A (H3N2) influenza virus. Studies in which CTL were generated in A-T plasmas and during co-culture of PBMC from an A-T patient and an MHC-matched sibling failed to demonstrate either plasma or cellular suppression as a mechanism for the lack of CTL production in A-T patients. This immune defect in the production of cytotoxic effector T cells may be a cause of the increased frequency of infections and neoplasms observed in A-T patients.

Adolescent↗
PubMed1983

A study of the functional capabilities of human neonatal lymphocytes for in vitro specific antibody production.

The ability of neonatal B and T cells to participate in the in vitro production of anti-influenza virus antibody was studied. Peripheral blood mononuclear cells from nearly all normal adults produce anti-influenza virus antibody when stimulated in vitro with type A influenza virus. Cord blood mononuclear cells, however, consistently failed to do so. Using Epstein-Barr virus activation or coculture with irradiated adult T cells in the presence of influenza virus to identify precursor B cells for anti-viral antibody production, newborns were found to have a decreased number of influenza-specific B cells as compared with adults. Thus, a paucity of precursor B cells for anti-influenza virus antibody was one factor contributing to the absent in vitro antibody response. Additional studies were undertaken to investigate the capabilities of newborn T cells in the in vitro response to influenza virus. Newborn T cells failed to proliferate when cultured with influenza virus. Irradiated newborn T cells were, however, able to provide help for specific antibody production in influenza virus-stimulated cocultures with allogeneic adult B cells, and newborn T cells proliferated when stimulated with alloantigens; their helper function in allogeneic coculture was, thus, likely mediated by T cells stimulated by alloantigens rather than by influenza virus. In the absence of T cell irradiation, no antibody was produced in cocultures of adult B cells and neonatal T cells, at least in part as the result of a radiosensitive suppressor T cell. Suppression in influenza virus-stimulated allogeneic cocultures was also observed with normal adult T cells and is, therefore, a property of both newborn and adult T cells. Thus, allogeneic help and suppression can both be manifested in exogenous antigen-stimulated allogeneic cocultures. In addition, both of these allogeneic effects can be mediated by neonatal T cells, indicating that these functions are present at the time of birth and do not require previous exogenous antigenic exposure for expression.

Adult↗
PubMed1983

Rapid extraction and gas-liquid chromatographic determination of benzoic and sorbic acids in beverages.

A rapid method for extraction and quantitative determination of sorbic and benzoic acids in carbonated drinks and fruit juices is described. Acidified sample aliquots are transferred onto an Extrelut column. Acid preservatives are then eluted from the column with a mixture of ethyl ether-petroleum ether. Content of preservatives in the concentrated ethereal extract is readily determined by temperature-programmed gas-liquid chromatography without the need to prepare derivatives.

Benzoates↗
PubMed1983

Biochemical studies of the excitable membrane of Paramecium tetraurelia. VII. Sterols and other neutral lipids of cells and cilia.

The neutral lipid content of cells and cilia of Paramecium tetraurelia was determined as a function of growth stage and of growth medium composition. The major sterol(s) of deciliated cells and of cilia were the sterol provided in the growth medium (e.g., stigmasterol) and its 7-dehydro derivative. Body sterol esters and triglycerides accumulated during exponential cell growth and became depleted during stationary phase. Isolated cilia contained neither sterol esters nor triglycerides. The ratio of phospholipid to free sterol in cilia was constant (approximately 5:1) throughout exponential growth in axenic or bacterized medium, but the relative proportions of free sterol and 7-dehydrosterol varied with growth phase and with growth medium composition. Cholesterol did not support the growth of Paramecium, but was taken up rapidly into cells and cilia as the free sterol and its 7-dehydro derivative. The fatty acids of sterol esters and of triglycerides were similar to those of membrane phospholipids.

Animals↗
PubMed1982

A Ca2+-activated ATPase specifically released by Ca2+ shock from Paramecium tetraurelia.

Deciliation of Paramecium tetraurelia by a Ca2+ shock procedure releases a discrete set of proteins which represent about 1% of the total cell protein. Marker enzymes for cytoplasm (hexokinase), endoplasmic reticulum (glucose-6-phosphatase), peroxisomes (catalase), and lysosomes (acid phosphatase) were not released by this treatment. Among the proteins selectively released is a Ca2+-dependent ATPase. This enzyme has a broad substrate specificity which includes GTP, ATP, and UTP, and it can be activated by Ca2+, Sr2+, or Ba2+, but not by Mg2+ or by monovalent cations. The crude enzyme has a specific activity of 2-3 mumol/min per mg; the optimal pH for activity is 7.5. ATPase, GTPase, and UTPase all reside in the same protein, which is inhibited by ruthenium red, is irreversibly denatured at 50 degrees C, and which has a sedimentation coefficient of 8-10 S. This enzyme is compared with other surface-derived ATPases of ciliated protozoans, and its possible roles are discussed.

Acid Phosphatase↗
PubMed1982

Human T-cell subset requirements for the production of specific anti-influenza virus antibody in vitro.

Studies were undertaken to define the helper T-cell requirements for in vitro specific antibody production to influenza virus. Subpopulations of human T cells were separated on the basis of their reactivity with the monoclonal antibody OKT4. B cells cultured with OKT4+ T cells produced specific antibody to influenza virus, while B cells cultured with OKT4- T cells did not. Irradiation (1200 rads) of the OKT4- subset to potentially eliminate suppressor-cell activity did not augment the helper-cell function of that subset. Thus, unlike the cytotoxic T-cell response to influenza, help for an in vitro antibody response is mediated only by OKT4+ T cells.

Adult↗
PubMed1982

Central serotonergic receptors: evidence for heterogeneity and characterization by ligand-binding.

Evidence has accumulated which suggests that receptors for serotonin exist in multiple forms both in the central nervous system and the periphery. This has come from the use of a variety of techniques and a number of different tissues. In the central nervous system the ligand-binding technique has proven particularly useful for characterizing different types of serotonin receptors, and two major classes of central serotonin receptors have been proposed on the basis of studies using this procedure. The first group (5-HT1 receptors) is defined by the high-affinity binding of 3H-serotonin in the brain, and the second (5-HT2 receptors) is defined by the high-affinity binding of 3H-spiperone in the frontal cortex. The 5-HT1 sites have themselves been shown to be a heterogeneous group, and recent studies suggest that it is possible to synthesize tryptamine analogues which can discriminate between the different types of 5-HT1 receptors. Such studies suggest the possibility of designing new selective serotonin agonists and antagonists for the study of the effects of specific receptor subtypes on behavioral and physiological activities.

Animals↗
PubMed1982

Secretory and systemic immunological response in children infected with live attenuated influenza A virus vaccines.

An enzyme-linked immunosorbent assay was used to measure isotype-specific antibody to purified hemagglutinin (HA) of influenza A virus, using serum and nasal-wash specimens from young children undergoing primary infection with live cold-adapted influenza A/Alaska/77 (H3N2) or A/Hong Kong/77 (H1N1) candidate vaccine virus. The serum antibody response followed the pattern expected for a primary viral infection. Each of 17 vaccinated children had a serum immunoglobulin G (IgG) HA antibody response, 16 had an IgM antibody response, and 13 had an IgA antibody response. Nasal-wash HA antibody was detected in the IgA, IgM, and IgG isotypes. Of the 17 vaccinated children, 14 had an IgA response, 13 had an IgM response, and 9 had an IgG response. Most of the IgA and IgM HA antibody was actively secreted locally, whereas only some of the IgG HA antibody could be shown to be actively secreted into the respiratory tract. There was a good correlation between the level of nasal-wash antibodies measured by the HA-specific IgA enzyme-linked immunosorbent assay and by a plaque neutralization assay. These data indicate that intranasal vaccination of susceptible children with live, attenuated, cold-adapted influenza A viruses efficiently stimulates both systemic and local antibody responses.

Antibody Formation↗
PubMed1982

Killing of measles virus-infected cells by human cytotoxic T cells.

Lymphocytes from normal individuals were tested for the capacity to generate measles virus-specific cytotoxic T-cell responses after in vitro stimulation with measles virus. Approximately 12% (5 of 40) of the normal adults tested produced significant cytotoxic responses. The cytotoxic response was measles virus specific both at the level of stimulation and at the effector level. Studies of the specificity of cytotoxic effectors from five normal donors by direct lysis or cold target inhibition or both indicated that most, if not all, of the virus-specific activity was self-specific. A detailed analysis of one donor (W6) indicated that measles-specific cytotoxicity was largely HLA-A and -B restricted; unexplained cross-reactive lysis was observed with some targets, but this lysis appeared to be HLA related, since all of the targets expressed HLA-B12. An analysis of the cellular requirements for the production of measles-immune cytotoxic T lymphocytes demonstrated that T cells and macrophages (depleted of natural killer and K cells) were sufficient for the generation of killer cells. Most of the cytotoxic effector activity was mediated by OKT3+ OKT4- OKT8+ cells.

Adolescent↗