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Biomedical subjects

D P Hartmann

Publications and source records attributed to D P Hartmann.

16 recordsLinked to original sources
PubMed1990

The psychological functions of preadolescent peer activities.

The psychological functions of preadolescent peer activities were assessed by examining activity-related prescriptions and prescriptions for peer behavior. 91 fifth- and sixth-grade children (48 girls) kept week-long diaries of important peer activities and liked and disliked behaviors performed by peers in the activities. 81 other fifth- and sixth-grade children (40 girls) rated the importance and prevalence of each activity and indicated which of several positive and negative behaviors they would most like or dislike to happen in 10 of the activities. Results indicate that collectively, the activities sampled serve 3 main functions based on their prescriptive and prescriptive behavioral profiles: (a) they provide a context for sociability, enhancement of relationships, and a sense of belonging; (b) they promote concern for achievements and integrity of the self; and (c) they provide opportunities for instruction and learning. Not all activities serve all functions, however, and children may require exposure to a variety of activities to accrue a full range of psychological experiences. The findings also illustrate the potential importance of activity-related information for discerning the meaning and evaluating the effectiveness of social behavior. The advantages of the methodology are discussed.

Child↗
PubMed1989

Human B cell lines can be triggered to secrete an interleukin 2-like molecule.

To determine whether human B cells can be triggered to secrete interleukin 2 (IL-2), 19 tumor cell lines derived from patients with undifferentiated lymphomas of Burkitt's and non-Burkitt's types and 6 normal lymphoblastoid cell lines were tested. Cells were grown in the presence or absence of the new tumor promoter teleocidin, and culture supernatants were assayed for IL-2 activity using the standard CTLL-2 assay. Teleocidin (10 ng/ml) triggered IL-2 secretion in 7/8 (87%) EBV-negative lymphoma cell lines of American origin and in 6/6 (100%) normal lymphoblastoid cell lines, but in only 1/6 (16%) EBV-positive tumor cell lines of American origin. Teleocidin had no effect on 5/5 (0%) African Burkitt's cell lines. IL-2 secretion was not detected in control supernatants. IL-2 secretion correlated with the induction of IgM secretion and was linked to both EBV status and karyotype. The following similarities in the functional biological characteristics of T cell and B cell IL-2 suggest that B cell IL-2 is not a factor which mimics IL-2 activity in the CTLL-2 assay: (i) neutralization of IL-2 by anti-IL-2 monoclonal antibody (DMS-1); (ii) elution of IL-2 following its adsorption to CTLL-2 cells; (iii) determination of the MW of IL-2 by SDS-PAGE and Western blot analysis; and (iv) ability of B cell IL-2 to support T cell proliferation and blocking of this activity by anti-tac monoclonal antibody. cDNA probes for T cell IL-2, however, did not detect IL-2 mRNA in B cells. The cell lines were also found to constitutively express IL-2 receptors detected by anti-tac monoclonal antibody, and to secrete soluble IL-2 receptors measured by ELISA. Our results imply that under certain circumstances, B cells can be triggered to secrete IL-2 or an IL-2-like molecule and thus influence T cell activation and proliferation.

Antibodies, Monoclonal↗
PubMed1989

Inhibition of lymphocyte proliferation by antibodies to prolactin.

Recent in vivo studies have shown that treatments that decrease circulating prolactin (PRL) in rodents result in significant immunosuppression. Our attempts to demonstrate corresponding direct stimulatory effects of PRL on cultured lymphocytes were unsuccessful. However, antibodies against pituitary PRL potently inhibited both murine and human lymphocyte proliferation in response to both T and B cell mitogens. Further studies using IL 2 and IL 4 responsive cell lines (CTLL-2 and HT-2) demonstrated that the same anti-PRL antibodies inhibited the proliferative response to these cytokine growth factors. Thus, antibodies to PRL appear to block an event occurring in the G1 to GS phase transition of these cell lines, which constitutively express growth factor receptors. The inhibitory activity of anti-PRL antibodies could be adsorbed by addition of purified human PRL or by immobilized PRL on an affinity column. Antibodies to other pituitary hormones were without inhibitory effect on CTLL-2 cell proliferation. Proliferation of lymphocytes in serum-free medium was also potently inhibited by anti-PRL antibodies, suggesting that antibody effects were not due to neutralization of PRL or other factors contained in culture serum supplements. We suggest from these data that a protein with homology to PRL and recognized by these anti-PRL antibodies is produced by lymphocytes and plays a critical role in their progression through the cell cycle.

Animals↗
PubMed1988

Detection of antigens associated with Epstein-Barr virus replication in extracts from biopsy specimens of nasopharyngeal carcinomas.

By using monoclonal antibodies to different Epstein-Barr virus (EBV) polypeptides in combination with immunoblotting, we detected antigens associated with EBV replication in extracts from nasopharyngeal carcinoma (NPC) biopsy specimens. Major polypeptides associated with both the diffuse and the restricted components of the early antigen (EA) complex were found in extracts from nine of nine NPC biopsy specimens. Cells from an additional NPC biopsy specimen, passaged repeatedly in nude mice, were found to be positive for the major EA (restricted) polypeptide. This approach revealed that extracts from three of 14 biopsy specimens form other benign and malignant diseases also expressed these viral polypeptides. Therefore, for the first time, these results conclusively demonstrate the presence of EA polypeptides in extracts from NPC biopsy specimens. This finding provides at least a partial explanation for the reported prognostic value of antibodies to this antigen in patients with this disease.

Antibodies, Monoclonal↗
PubMed1988

Recent developments in single-subject methodology: methods for analyzing generalization, maintenance, and multicomponent treatments.

At the outset of this chapter we asked whether or not single-subject methodology has outlived its usefulness to behavior therapy. We did so because serious doubts have been expressed about the ability of single-subject methodology to address the salient issues of the day. This chapter allays many of these doubts. This chapter reveals that single-subject researchers are far from helpless when investigating generalization and maintenance and identifying the active (and inactive) components in their compound treatments. In fact, a number of powerful strategies are at their disposal--strategies that are not strangers to the armamentarium of single-case researchers. These strategies are in essence nothing more than extensions of the reversal, multiple baseline, and simultaneous and alternating-treatments designs. In the case of the assessment of generalization, these extensions involve little more than the inclusion of continuous measures (or regular probes) of untrained responses throughout the investigation. In the case of the assessment of maintenance, they involve the replacement of a comparison of two or more acquisition procedures with a comparison of two or more maintenance procedures. And in the case of the identification of active (and inactive) components of compound treatments, they involve the aggregation of the findings from a series of single-subject investigations. When the requirements of single-subject designs and their extensions cannot be met, investigators still have available a set of traditional group designs (e.g., factorial and additive designs) for attacking these same issues. Assessment of generalization, maintenance, and the components of compound treatments are not the only salient issues facing behavior therapy today. Another is the widening gap between the researcher and the practitioner (e.g., Barlow, 1980; Wilson, 1981). It is thought by some that single-subject methodology may be the means of bridging this gap; that through single-subject methodology a new breed of practitioner will appear: the empirical clinician (e.g., Barlow et al., 1984; Goldfried, 1984; Hayes, 1981). This new breed of practitioner will be made up of persons who, for economic and pragmatic reasons, are concerned with accountability and who use single-subject designs to achieve it (Barlow et al., 1984). The present chapter does little to help bridge the gap between the researcher and the practitioner; thus, the present chapter does little to help bring about the creation of this new breed of practitioner, the empirical clinician. In fact, the single-subject strategies described in these pages appear to be suitable for use only by the researcher.(ABSTRACT TRUNCATED AT 400 WORDS)

Behavior Therapy↗
PubMed1987

Cytomegalovirus encephalitis associated with episodic neurologic deficits and OKT-8+ pleocytosis.

After 3 days of symptoms suggesting a viral illness, a 35-year-old man experienced three episodes of aphasia, right-sided sensory symptoms, and bifrontal headache. Each lasted several hours. CSF examination revealed a moderate lymphocytosis consisting of 80% OKT-8+ cells. Serum anti-cytomegalovirus (anti-CMV) antibody titer was elevated at 1:1,024 and subsequently fell to 1:64. Episodic symptoms recurred 5 months later, at which time the anti-CMV titer peaked at 1:8,192. A trial of inhaled oxygen aborted two episodes after several minutes each.

Adult↗
PubMed1987

Leukotrienes, thromboxane, and platelet activating factor in organ transplantation.

The antirejection eicosanoids--PGE2, (PGD2), and PGI2--have an attenuating effect on T-cell proliferation by inhibition of IL-1, IL-2, and class II antigen expression on macrophages, and the prorejection eicosanoids--TXA2, LTB4, LTC4, and LTD4--enhance T-cell proliferation. LTB4 stimulates IL-1 and IL-2 formation and expression of IL-2 receptor. The mechanism of enhancement of T-cell proliferation by TXA2 has not been demonstrated. LTC4 and LTD4 promote gamma-interferon release and can replace IL-2 as a stimulator of gamma-interferon. PAF at high concentrations inhibits lymphocyte proliferation. The eicosanoids interfere with the same mechanisms as CsA and corticosteroids on T-cell clonal expansion. In experimental organ transplantation, corticosteroids can be replaced by compounds preventing the formation or expression of the prorejection eicosanoids or analogs of antirejection eicosanoids as well as by PAF antagonists. In addition, these drugs exert synergistic effect with CsA and azathioprine.

Animals↗
PubMed1986

Burkitt's cells can be triggered by teleocidin to secrete interferon-gamma.

The secretion of interferon (IFN)-gamma by T lymphocytes is mediated by the synthesis of interleukin 2 (IL-2) and the availability of IL-2 receptors. Since some Burkitt's lymphoma lines express Tac antigen and can be triggered to secrete IL-2 following activation with the new tumor promoter teleocidin, we addressed the question of whether the induction of IL-2 by B lymphocytes is accompanied by the induction of IFN-gamma. IFN-gamma has not been detected in any of the 25 cell lines studied, and following stimulation with teleocidin, we triggered the synthesis of IFN-gamma in JLP(C), a pre-Burkitt's cell line. The mechanism of IFN-gamma secretion by B lymphocytes is not clear. Our findings demonstrate that the synthesis of IL-2 by B cells is not accompanied by IFN-gamma and suggest that the synthesis of IFN-gamma is not mediated by IL-2 or IL-1 or B-cell growth factor. Neutralization studies have shown that IFN-gamma secretion is not accompanied by the induction of IFN-alpha or IFN-beta. Our data imply that B cells can be triggered to secrete IFN-gamma under certain circumstances. Whether similar function occurs in vivo is not known.

Animals↗
PubMed1985

Why does children's generosity increase with age: susceptibility to experimenter influence or altruism?

This study evaluated whether age differences in children's generosity are due to increasing altruistic motivation or increasing susceptibility to experimenter influence strategies. 282 first, third, and fifth graders voted on how to spend a gift of money under 1 of 5 instructional sets--3 levels of experimenter influence, peer influence, or no influence, or no influence. Voting choices (in increasing order of generosity according to experimenter-defined scoring weights) were splitting up the money equally among class members, buying something for their class, buying something for their school, or giving the money to poor children. Voting choices also were scored according to empirically derived weights based on rankings provided by an independent sample of 50 first, third, and fifth graders. Both scoring systems indicated that fifth graders were more generous than younger children, but only under high levels of experimenter demand, and peer influence did not increase children's generosity. Furthermore, first graders appeared more generous when the child-derived rather than the experimenter-derived scoring system was used. Thus generalizations regarding age differences in generosity observed in laboratory experiments may require qualification, specifying the degree and type of experimenter influence involved.

Altruism↗
PubMed1979

Immune derangement in patients with malignant melanoma.

The interaction between immune system and growing tumor can be expressed differently at different stages of the disease. This presentation covers three facets of these reactions in melanoma patients. A. The Primary Tumor. Time-lapse cinematography, with an analysis of lymphocyte movement demonstrated positive and negative chemotaxis against tumor tissues which correlated with their histological presence or absence within the primary tumor. B. The Regional Lymph Nodes. Histological examination of regional lymph nodes showed an increase in germinal center activity and B cell number, with a decrease in sinus histiocytosis and monocyte count as the tumor progressively invaded the node. This correlated with the elution studies, wherein the antimembrane antibody decreased and the anti-cytoplasmic antibody increased during the same period of progression. C. Humoral Immunity and Metastasis. Clinical metastasis heralded the decrease of anti-membrane antibodies with a rise in anti-immunoglobulins, especially anti-idiotypic antibodies and immune complexes containing tumor-directed antibody and either antigen or anti-immunoglobulin. This triad of anti-immunoglobulin, immune complexes and anergy as seen in other diseases with persistent antigenic stimulation, results in abnormal regulation and derangement.

Antibodies, Neoplasm↗
PubMedDate not supplied

The changing criterion design.

This article describes and illustrates with two case studies a relatively novel form of the multiple-baseline design called the changing criterion design. It also presents the design's formal requirements, and suggests target behaviors and circumstances for which the design might be useful.

Adult↗