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Results for “memory differentiation”

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PubMed1976

Immunoglobulin M receptors on memory cells of immunoglobulin G antibody-forming cell clones.

The memory cells of two antibody-forming cell clones had receptors of the IgM class, even though the clones had been producing IgG1 or IgG2a anti-2,4-dinitrophenyl antibodies for 9-15 months previously (on exposure to antigen). Thus a phenotypic switch in heavy chain constant region evidently occurred after re-exposure of these memory cells to antigen. To show that, we first removed the clonal cells' surface immunoglobins by "capping" and "stripping", with class- or subclass-specific antisera. Then, to assay their remaining receptor activity, the cells were incubated with antigen in vitro, washed and transferred (together with carrier primed cells) to irradiated recipients, and their antibody responses to this in vitro boost were assayed by iselectric focusing. Pretreatment with anti-mu serum, as well as with anti-Fab(kappa), prevented the responses of the IgG1 and IgG2a clones to an in vitro boost, while anti-gamma1 and anti-gamma2a antisera had no effect. An antiserum to the putative mouse IgD also had no effect. The anti-mu serum failed to react with the IgG1 and IgG2A clonal serum antibodies in the test tube. Some other contaminating clones were suppressed completely only by the anti-Fab serum. This result strongly suggests that switching in class commitment may occur during the differentiation of memory cells to antibody producers, and may therefore be antigen-dependent. It also implies that some apparently naive cells with surface IgM may, in reality, be B memory cells.

Animals↗
PubMed1977

The differential effects of meclofenoxate on memory loss in the elderly.

A double-blind study of the effects of meclofenoxate on memory performance of fit, able, elderly subjects was carried out. A number of performance measures, designed to measure various aspects of memory function were employed. These revealed that meclofenoxate appears to increase the consolidation of new information into long-term memory, but does not affect other aspects of remembering. It was also found that significantly more of the subjects receiving meclofenoxate reported an increased level of mental alertness.

Aged↗
PubMed2026

Human GPR174 deficiency drives polyclonal lymphoproliferative disease via defects in T cell function.

The X-linked G-protein coupled receptor GPR174 is highly expressed in T and B lymphocytes and has immunoregulatory roles in mice, but its function in humans is unknown. We describe a cohort of six individuals who have function-disrupting variants in GPR174 and a clinical phenotype of lymphadenopathy and autoimmunity. Histological analysis of two patient lymph nodes revealed necrotizing lymphadenitis and lymphoproliferation resembling Kikuchi-Fujimoto disease. In-depth analysis of three patients and related carriers revealed overaccumulation of CD8 terminally differentiated effector memory cells re-expressing CD45RA (TEMRA). Patient cells and GPR174-deficient CD8 T cells generated from controls showed less repression of proliferation by the GPR174 ligand lysophosphatidylserine (lysoPS) and an effector-biased gene expression program. GPR174-deficient CD4 T cells were resistant to lysoPS-mediated suppression of IL2 production. In mice, chronic viral infection led to over-accumulation of GPR174-deficient effector CD8 T cells. We describe an inborn error of immunity associated with dysregulated lymphocyte responses that we propose predisposes to exaggerated lymphoproliferation and autoimmunity following viral infection.

Journal Article↗
PubMed1979

[A tapeworm infection with fatal outcome (author's transl)].

Parasitoses of the intestinal tract are rare in Europe. Their diagnosis is difficult since the general symptoms are frequently only little pronounced or completely lacking. On the other hand, the course of the disease may be fatal. Such cases from the literature and our own observations are intended to call to memory the differential diagnosis of intestinal parasitosis.

Aged↗
PubMed1979

Memorizing and copying visual patterns: a Piagetian interpretation.

Six-, 8-, 10-, and 12-year-old children (10 boys and 10 girls) reconstructed two visual patterns from immediate memory, while other 5- and 6-year-old children (10 boys and 10 girls) reconstructed the identical patterns by direct copying. Patterns were simple and composed entirely of circles or squares as component items. Four results were emphasized: (a) Numerous errors mady by the copying groups led to the conclusion that memory loss is often overestimated in young children. Since an independent estimate of perceptual encoding errors is rarely carried out, encoding mistakes are often included among forgetting errors. (b) One pattern was both copied and remembered more poorly than the other in accord with a Piagetian interpretation of a conceptual conflict inherent in the pattern design between spatial and numerical correspondence of component pattern items. (c) A memory strategy emphasizing configuration preservation was suggested for the 6-year-olds who made slightly fewer memory than copying errors for two configural scoring categories. (d) Performance in an unrelated planning-for-memory task significantly differentiated between better and worse performers on the visual pattern memory task.

Age Factors↗
PubMed1976

Comparative studies on the actions of antigen and polyclonal B-cell activator in differentiation and proliferation of B-cells and B memory cells.

Using the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) as a polyclonal B-cell activator (PBA) and sheep red blood cells (SRBC) as a T cell-dependent antigen, we compared the ability of PBA and antigen to differentiate (generate antibody-forming cells, AFC) and proliferate (generate immunological memory) virgin B cells and B memory cells. In vitro CPS-K induced the differentiation of IgM virgin B cells, IgM B memory cells and IgG B memory cells to AFC, as well as or better than SRBC. The differentiation of B memory cells to AFC by CPS-K did not require the participation of macrophages or T cells, whereas the action of SRBC depended strictly upon the helper actions of these cells. The responsiveness to CPS-K and SRBC of normal and antigen-primed spleen cells as judged by anti-SRBC PFC responses in vitro was markedly decreased after stimulation of virgin B cells and B memory cells in vivo by CPS-K injection into normal or primed mice but greatly increased after the injection of SRBC. The decrease in the responsiveness to CPS-K of spleen cells from mice treated with CPS-K appeared principally due to exhaustion of the functions of B cells and B memory cells. From the present data it has been concluded that the signals required for the differentiation and proliferation of B cells of B memory cells are different from each other, the signal for differentiation being provided by either antigen (SRBC) or PBA (CPS-K), while the signal for proliferation only by antigen.

Animals↗
PubMed1977

Levodopa, parkinsonism, and recent memory.

Much controversy has existed concerning behavioral changes attributed to L-dopa treatment in parkinsonian patients. Disagreement existed pertaining to the question of whether improved functioning was temporally limited. The present study proposed to research the shorter and longer range effects of L-dopa onmemory. It was hypothesized that equated nonparkinsonian individuals would perform better than parkinsonian patients on all memory measures, and that shorter range L-dopa would perform better than longer range L-dopa patients. It was also hypothesized that the greater the functional deficiency, and the greater the symptom severity, the poorer memory functioning would be. Level of dosage was hypothesized to have no differential effect on memory functioning. Three groups of 20 subjects were tested. The short term (20 parkinsonian patients on L-dopa for 22 months or less) and the long term (20 parkinsonian patients on L-dopa for 40 months or more) patients were chosen from the neurological clinic at St. Barnabas Hospital, Bronx, N.Y. Testability was assessed by the neurologis and by WAIS Vocabulary performance. The third group consisted of spouses of the patients. All groups were equated with regard to sex, age, education, and where applicable, length of illness, functional status, and symptom severity. The instruments used to measure memory consisted of the Guild Memory Test, the Memory Span for Objects, the Knox Cube, and the Tactile Memory Test. WAIS Vocabulary scaled score was used as a covariate in an analysis of covariance on each of the nine memory subtests. Statistically significant differences were obtained at the .01 level among groups on all measures. Orthogonal comparisons resulted in significant differences at the .01 level between parkinsonian patients and nonparkinsonian subjects on all measures. Short term and long term L-dopa patients differed significantly on six of the nine measures, notably those testing verbal types of memory. Significant correlations were obtained between functional deficiency and eight measures; however, symptom severity correlated with only one measure. None of the memory measures correlated significantly with level of dosage. The major conclusion was reached that all of the initial improvement shown following L-dopa initiation is not sustained permanently; the elevated level of memory functioning appears to be temporally limited.

Humans↗
PubMed1979

Benzodiazepines alter acquisition and retention of an inhibitory avoidance response in mice.

These experiments were performed to examine the effects of graded doses of diazepam, flurazepam, or lorazepam given to Swiss-Webster mice either 30 min prior to training or immediately after training in a one-trial inhibitory (passive) avoidance task. A 350 MUA footshock was administered following entry into a darkened compartment and retention was tested three days later. Doses of 10.0 mg/kg diazepam and 20.0 mg/kg lorazepam given before training significantly impaired acquisition, while 1.0 mg/kg flurazepam, given immediately after training, produced retrograde amnesia. These results indicate that benzodiazepines affect memory processes and that various drugs of the benzodiazepine family differentially affect acquisition and memory consolidation.

Animals↗
PubMed1976

Some considerations of two alleged kinds of selective attention.

The present article deals with selective attention phenomena and elaborates on a stimulus material classification, "stimulus set" versus "response set," proposed by Broadbent (1970, 1971)9 Stimulus set is defined by some distinct and conspicuous physical properties that are inherent in the stimulus. Response set is characterized by the meaning it conveys, and thus its properties are determined by cognitive processing on the part of the organism. Broadbent's framework is related to Neisser's (1967) distinction between two perceptual-cognitive processes, namely, preattentive control and focal attention. Three experiments are reported. A before-after paradigm was employed in Experiment 1, together with a sptial arrangement manipulation of relevant versus irrelevant stimuli (being grouped or mixed). The results indicated that before-after instruction had a stronger effect under stimulus set than under response set conditions. Spatial arrangement, on the other hand, affected performances under response set but not under stimulus set conditions. These results were interpreted as supporting the idea that stimulus set material, which is handled by preattentive mechanisms, may be processed in parallel, while response set material requires focal attention that is probably serial in nature. Experiment 2 used a search task with different levels of noise elements. Although subjects were not able to avoid completely the processing of noise elements, they had much more control under stimulus set than under response set conditions. Experiment 3 dealt with memory functions and suggests differential levels of perceptual processing depending on the nature of the stimulus material. This extends the memory framework suggested by Craik and Lockhart (1972). The results of these experiments, together with evidence from other behavioral and physiological studies, lend strong support to the proposed theory. At the theoretical level, it is suggested that the distinction between stimulus and response set, and the corresponding one between preattentive mechanisms and focal attention, are on a continuum rather than being an all-or-none classification. Thus, it permits greater congnitive flexibility on the part of the organism, which is reflected through the assumption that both preattentive mechanisms and focal attention may operate simultaneously and differ only in the salience of their functioning. From a methodological point of view, the distinction between stimulus material and organismic processes is emphasized. It is argued that researchers have not given sufficient attention to the properties of the stimulus materials that they have used, and as a consequence have reached unwarranted conclusions, as exemplified by a few studies that are briefly discussed.

Attention↗
PubMed1976

Protection against murine ascites tumours by lymphoid cell populations with T memory or cytotoxicity.

It was possible to protect irradiated C3H mice against lethal doses of allogeneic ascitic tumor cells (RBL-3 or P-815 Y) by systemic administration of low doses of syngeneic sensitized lymphoid cells. Two types of cell populations were active at similar doses: (1) spleen cells harvested 2 months after a nonlethal inoculation of tumour cells, at which time no cytotoxic lymphocytes wer in vivo sensitization or in vitro sensitized spleen cells; sucll and dose dependent and target cell specific. The findings imply that T memory cells as well as cytotoxic cells are able to protect, although it was not possible to exclude the presence of memory lymphocytes in the cytotoxic cell population. Antiserum to cytotoxic T cells (CTL) was prepared in an attempt to distinguish memory and cytotoxic effector cells. The antiserum did not react with the majority of T cells in a normal spleen or thymus, but showed specificity for the CTL cell lineage. Antiserum treatment and complement abolished protection in all types of sensitized cell populations. Since memory and cytotoxic cells appeared to share differentiation antigens, we could not establish whether memory cells are precursors or products of cytotoxic cells.

Animals↗
PubMed1979

B-cell influences on the induction of allotype suppressor T cells.

Allotype suppressor T-cell (Ts) populations that persist for the life of the animal arise in (BALB/c x SJL)F(1) hybrids exposed perinatally to antibody to the paternal (Ig-1b) allotype on IgG(2a)-isotype immunoglobulin H chains. These Ts suppress Ig-lb production by depleting the supply of allotype- specific helper T cells (Th) required, in addition to carrier-specific Th, for the latter stages of Ig-1b memory B-cell differentiation. In this publication, we show that specific Ig-1 allotype Ts are induced by perinatal exposure to antisera which interfere with normal B-cell maturation, i.e., by antibodies reactive with surface IgM on immature precursors of IgG(2a), memory cells. Antibodies to IgM (Ig-6) allotypes carried on precursors induce specific suppression for the IgG2, allotype produced by progeny of the target precursor. Anti-Ig-6a and anti-Ig-6b induce Ts that specifically suppress Ig-1a and Ig-1b, respectively. Heterologous (goat) anti-IgM induces suppression for both IgG(2a) immunoglobulins (Ig-1a and Ig-1b). Ts activity in these antiprecursor-Ig-suppressed mice is expressed in adoptive transfer assays and, as with anti-Ig-1b-induced Ts, is rendered ineffective by cotransfer of adequate numbers of T cells but not B cells from nonsuppressed mice. The Ts induction, in contrast with Ts expression, is reversed by the introduction of appropriate adult B-cell populations from nonsuppressed donors. Taken together, these data suggest that the development of mature B cells plays a central role in the early establishment of the balance between helper cells and suppressor cells that determines whether Ts or Th will dominate in regulating Ig-1b production in adult animals.

Age Factors↗
PubMed1978

Optimal strategies in immunology. II. B memory cell production.

After a first encounter with most antigens, the immune system responds to susequent encounters with a faster, more efficient and more strenuous antibody response. The memory of previous antigen contacts is carried by lymphocytes. Expanding on the model developed in Part 1 of this paper, we examine the optimal strategy available to the immune system for B memory cell production. We again find that the strategy should be of the bang-bang variety. The model we consider assumes that antigen triggers a subpopulation of B-lymphocytes. These triggered lymphocytes can proliferate and secrete modest amounts of antibody, or differentiate into non-dividing plasma cells which secrete large amounts of antibody, or differentiate into non-antibody secreting memory cells. Given injections of antigen at two widely spaced times we compute the strategy which minimizes a linear combination of the primary and secondary response times. We find that for all biologically reasonable parameter values the best strategies are ones in which memory cells are produced at the end of the primary response. Exerimental results which bear on the actual strategies employed are discussed.

Antibody Formation↗