Search PubMed⌕ Search

Biomedical subjects

D P Hartmann

Publications and source records attributed to D P Hartmann.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1984

Enhanced interleukin activity following asbestos inhalation.

Asbestos inhalation can cause pulmonary fibrosis and is associated with a variety of immunological abnormalities. The purpose of this study was to evaluate the effects of asbestos inhalation on interleukin-1 (IL-1) and interleukin-2 (IL-2) production in a rodent model. Two groups of rats were exposed, by intermittent inhalation, to either amphibole (crocidolite) or serpentine (chrysotile) asbestos. A third (control) group of rats was sham exposed to clean air. Animals from the three exposure groups were thereafter immunized (or not immunized) with fetal calf serum antigens. In order to assay interleukin activity, supernatants were generated from cultures containing alveolar macrophages and autologous splenic lymphocytes, and from cultures containing alveolar macrophages alone. Using assay systems designed to detect IL-1 and IL-2 functional activity, the supernatants were evaluated for their capacity to stimulate lymphoproliferation and fibroblast DNA synthesis. Macrophage-lymphocyte co-culture supernatants, when obtained from immunized, asbestos exposed rats, contained greater IL-1 and IL-2 activity than identical supernatants from immunized, sham exposed animals. These between group differences were not, however, observed in supernatants from unimmunized rats, or when supernatants were generated in the absence of immune lymphocytes. These observations suggest that asbestos exposure is associated with enhanced activation of lymphocytes by antigens. The possible relevance of these findings to asbestos related fibrogenesis and immunological stimulation is discussed.

Animals↗
PubMed1983

The effects of chrysotile and crocidolite asbestos on the lower respiratory tract: analysis of bronchoalveolar lavage constituents.

This study was designed to evaluate the effects of amphibole and serpentine asbestos inhalation on the constituents of the lower respiratory tract. Bronchoalveolar lavage (BAL) analyses were performed on three groups of rats: one group was exposed to chrysotile (serpentine) asbestos, another group was exposed to crocidolite amphibole asbestos, while a third group was sham-exposed. Intermittent inhalational exposures lasted three months. The total BAL cell yields and the macrophage content of BAL cells were significantly lower after asbestos exposure, especially in the chrysotile-exposed group. These effects persisted for as long as 1 year after the cessation of exposure. Multinucleated macrophages were seen in BAL cells from both asbestos-exposed groups. Striking ultrastructural alterations of macrophage morphology were noted in BAL cells from both groups of asbestos-exposed rats. Chrysotile fibers were not seen in any BAL cells from chrysotile-exposed animals. However, 15 months after terminating the exposure regimen, a sizeable proportion of BAL macrophages from crocidolite-exposed rats contained phagocytosed asbestos fibers. Significantly higher beta-glucuronidase and lactate dehydrogenase activity was found in BAL fluids from both asbestos-exposed groups and was detected 17-18 months after exposure had ceased. These observations have served as useful correlates of asbestos-mediated injury to the lower respiratory tract. They have also provided evidence of continual pathological sequelae occurring long after withdrawal from asbestos exposure.

Animals↗
PubMed1983

Enhanced release of a chemoattractant for alveolar macrophages after asbestos inhalation.

Alveolar macrophage supernatants from 2 groups of asbestos-exposed rats and a group of sham-exposed rats were tested for chemoattractant activity towards rat alveolar macrophages. Enhanced chemotaxin release was observed in culture supernatants from both crocidolite and chrysotile asbestos-exposed rats when compared with supernatants from sham-exposed rats. These between-group differences persisted for as long as 15 months after exposure had ceased. Chemotactic factor release was maximal after 24 h of culture in all animal groups. Partial characterization of the chemoattractant from each of the 3 rat groups revealed that it was thermolabile, nondialyzable, and trypsin-sensitive. Separation on SDS-polyacrylamide gel electrophoresis revealed 3 major peaks of activity. The production of the chemotaxin in supernatants from asbestos-exposed rats was partially inhibited by both actinomycin D and puromycin. These agents had no appreciable effect on the production of chemoattractant in cultures from sham-exposed animals. The enhanced release of an alveolar macrophage chemoattractant after asbestos inhalation may explain why macrophages accumulate at sites of asbestos deposition in the lungs.

Aerosols↗
PubMed1982

A critical appraisal of meta-analysis.

Meta-analysis is an increasingly popular, objective method for summarizing a body of empirical findings. The standard meta-analysis package consists of methods for estimating the combined probability and average effect size for a set of studies, the stability of these results, and the factors associated with differential treatment outcomes. While meta-analysis is a powerful analytic technique, the procedure has limitations that should be carefully evaluated when it is applied to the psychotherapy--or any other--literature. These limitations include biased selection of studies; reporting inaccuracies, poor quality data, various sources of invalidity (conceptual, methodological, and statistical), and lack of independence in the studies reviewed; and variability in outcome produced by the meta-analytic techniques employed. Despite these potential problems, the advantages of meta-analysis are so substantial that the techniques deserve routine use as an aid to summarizing treatment literatures.

Humans↗
PubMed1982

A cautionary note on the use of probability values to evaluate interobserver agreement.

Proposed methods of assessing the statistical significance of interobserver agreements provide erroneous probability values when conducted on serially correlated data. Investigators who wish to evaluate interobserver agreements by means of statistical significance can do so by limiting the analysis to every k(th) interval of data, or by using Markovian techniques which accommodate serial correlations.

Journal Article↗
PubMed1982

Frequency and distribution of papillomavirus structural antigens in verrucae, multiple papillomas, and condylomata of the oral cavity.

Sixty-seven proliferous squamous epithelial lesions of the oral cavity were examined for the presence of human papillomavirus whole (structural) virion antigens by a peroxidase-antiperoxidase technique having immunospecificity against genus-specific (common) antigens of the papillomaviruses. A positive reaction for papillomavirus genus specific antigens was found in 18 of 29 verrucae, 2 of 5 multiple papillomas, and 3 of 5 condylomata; common antigens were not detected in 28 keratoacanthomas. The positive reaction was invariably intranuclear in cells having a focal or diffuse distribution in the superficial epithelium. This study shows that a variety of squamous epithelial lesions of the mucosa are associated with human papillomaviruses and suggests that these viruses may play an important role in the etiology of some cases of squamous hyperplasia of the oral cavity.

Adolescent↗
PubMed1980

Interrupted time-series analysis and its application to behavioral data.

This paper uses a question-and-answer format to present the technical aspects of interrupted time-series analysis (ITSA). Topics include the potential relevance of ITSA to behavioral researchers, serial dependency, time-series models, tests of significance, and sources of ITSA information.

Journal Article↗
PubMed1980

Protection against amebic liver abscess in hamsters by means of immunization with amebic antigen and some of its fractions.

Immunization of hamsters by intramuscular injections of an amebic extract and of two of its fractions, emulsified with complete Freund's adjuvant, resulted in protection against the development of amebic liver abscess, following intrahepatic inoculation of axenic trophozoites of Entamoeba histolytica such that Fraction I, Fraction II, and the whole antigen conferred protection to 18 out of 18, 4 out of 18, and 11 out of 18 hamsters, respectively. Splenomegaly was found to accompany the development of hepatic liver abscesses in this experimental system. There was a very high degree of correlation (r = 0.95) between the weights of the abscesses and the spleens. On the other hand, there was no correlation between the anti-amebic antibody titers (determined by the indirect hemagglutination test) and the development of the liver abscesses within the time-span of the experimental protocol used in this study.

Animals↗