The essential role of stimulus temporal patterning in enabling perceptual learning

Little is known about how temporal stimulus factors influence perceptual learning. Here we demonstrate an essential role of stimulus temporal patterning in enabling perceptual learning by showing that 'unlearnable' contrast and motion-direction discrimination (resulting from random interleaving of stimuli) can be readily learned when stimuli are practiced in a fixed temporal pattern. This temporal patterning does not facilitate learning by reducing stimulus uncertainty; further, learning enabled by temporal patterning can later generalize to randomly presented stimuli.     

Serological studies of monoclonal RH1(D) antibodies with RH1(D) variants

In this paper we chose to emphasize three aspects of our work. First we underlined that “low grade and high grade” D weak red blood cells studied at the DNA level could, when monoclonal antibodies were used, give patterns of positive and negative reactions like partial RH1(D) cells. Secondly, we showed the importance of the technical conditions of the study which are essential for establishing a pattern of reactivity defining an epitope. It appears that the use of papain treated cells at room temperature can be misleading for the definition of epitope especially with IgM antibodies. Lastly we pointed out the interest of Rh variant cells, defined at the gene level, to study the expression of RH1(D) epitopes on the external part of the membrane.     

Der Einfluss von Trijodthyropropionsäure und Trijodthyroessigsäure auf den Jodumsatz der Schilddrüse des Menschen

Zusammenfassung 1. Der Jodumsatz gesunder Schilddrüsen und blander Strumen wurde durch eine ein- bis dreiwöchige Medikation von täglich 0,5–2,0 mg Trijodthyropropion- oder Trijodthyroessigsäure per os gehemmt. Kleinere Dosen ließen diesen Einfluß bis auf eine Ausnahme vermissen, bei zwei blanden Strumen blieben auch 1,0 mg des Essigsäurederivates täglich ohne Wirkung. Der Sauerstoffverbrauch und Hormonjodgehalt des Blutes wurden durch die Zufuhr der beiden Metaboliten in keinem dieser Fälle wesentlich verändert.2. Zwei Kranke mit extrathyreoidalem Hypometabolismus wiesen insofern noch besondere Verhältnisse auf, als durch 0,1 mg Trijodthyropropionsäure bzw. 1,0 mg Trijodthyroessigsäure täglich der Sauerstoffverbrauch eindeutig zunahm und der Hormonjodspiegel einmal abfiel.3. Der thyreoidale Jodumsatz von Hyperthyreosen, einer euthyreotischen endokrinen Ophthalmopathie und einer Struma mit Rückstoß-Phänomen wurde durch die beiden Verbindungen nicht beeinflußt.Zwischen der Rückwirkung von genuinen Schilddrüsenhormonen und ihren Metaboliten auf den Jodumsatz der Schilddrüse bestehen erhebliche quantitative und gelegentlich auch qualitative Unterschiede. Deren Bedeutung wird erörtert.Die Untersuchungen wurden mit freundlicher Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.     

Microbial infections,immunomodulation, and drugs of abuse

The use of recreational drugs of abuse has generated serious health concerns. There is a long-recognized relationship between addictive drugs and increased levels of infections. Studies of the mechanisms of actions of these drugs became more urgent with the advent of AIDS and its correlation with abused substances. The nature and mechanisms of immunomodulation by marijuana, opiates, cocaine, nicotine, and alcohol are described in this review. Recent studies of the effects of opiates or marijuana on the immune system have demonstrated that they are receptor mediated, occurring both directly via specific receptors on immune cells and indirectly through similar receptors on cells of the nervous system. Findings are also discussed that demonstrate that cocaine and nicotine have similar immunomodulatory effects, which are also apparently receptor mediated. Finally, the nature and mechanisms of immunomodulation by alcohol are described. Although no specific alcohol receptors have been identified, it is widely recognized that alcohol enhances susceptibility to opportunistic microbes. The review covers recent studies of the effects of these drugs on immunity and on increased susceptibility to infectious diseases, including AIDS.     

Unterschiede in der Widerstandskraft der weiblichen und männlichen Keimdrüse

Ohne ZusammenfassungMit 15 Textabbildungen.Das Bedürfnis nach Stützung schwächerer Gedanken durch stärkere wird auchKausalitäts bedürfnis genannt und ist die Haupttriebfeder aller naturwissenschaftlichenErklärungen. Ernst Mach.Nach einem auf der 89. Versammlung deutscher Naturforscher und Ärzte in Düsseldorf im September 1926 gehaltenen Vortrage. Vgl. auch Fortschritte d. naturwissenschaftl. Forschung, herausgeg. vonE. Abderhalden, Bd. XII, H. 4.     

Severe meningococcal disease is characterized by early neutrophil but not platelet activation and increased formation and consumption of platelet-neutrophil complexes

Approximately 25% of polymorphonuclear leukocytes (PMNL) circulate in heterotypic complexes with one or more activated platelets. These platelet-neutrophil complexes (PNC) require platelet CD62P expression for their formation and represent activated subpopulations of both cell types. In this study, we have investigated the presence, time course, and mechanisms of PNC formation in 32 cases of severe pediatric meningococcal disease (MD) requiring intensive care. There were marked early increases in PMNL CD11b/CD18 expression and activation, and reduced CD62L expression compared with intensive care unit control cases. Minimal platelet expression of the active form of alphaIIbbeta3 (GpIIb/IIIa) was seen. PNC were reduced on presentation and fell to very low levels after 24 h. Immunostaining of skin biopsies demonstrated that PNC appear outside the circulation in MD. In vitro studies of anticoagulated whole blood inoculated with Neisseria meningitidis supported these clinical findings with marked increases in PMNL CD11b/CD18 expression and activation but no detectable changes in platelet-activated alphaIIbbeta3 or CD62P expression. In vitro PMNL activation with N. meningitidis (or other agonists) potentiated the formation of PNC in response to platelet activation with adenine diphosphate. Therefore, in severe MD, PMNL activation is likely to promote PNC formation, and we suggest that the reduced levels of PNC seen in established MD reflect rapid loss of PNC from the circulation rather than reduced formation.     

Conservation of salivary glycoprotein-interacting and human immunoglobulin G-cross-reactive domains of antigen I/II in oral streptococci.

In this study we localized more precisely the salivary glycoprotein-interacting and the human immunoglobulin G (hIgG)-cross-reacting domains on the SR molecule, an antigen I/II-related protein from S. mutans serotype f. Mapping of the SR molecule with polypeptides expressed by subclones covering the entire molecule and with synthetic peptides demonstrates that the salivary glycoprotein-binding domain is located in the N-terminal alanine-rich repeats of the SR molecule. In order to investigate the degree of conservation of both regions in various oral streptococci, we tested the reactivity of 8 representative strains of the mutans group and 11 nonmutans oral Streptococcus strains (S. anginosus, S. milleri, S. constellatus, S. intermedius, S. mitis, S. sanguis, S. gordonii, S. salivarius, and S. mitis strains) with antipeptide antibodies in a whole-cell enzyme linked immunosorbent assay together with colony hybridization analysis using DNA probes designed to map these two regions. All the mutans group strains except S. rattus and the 11 nonmutans streptococcal strains showed a high conservation of the C-terminal part of the SR molecule, especially the hIgG-cross-reacting domain, and less homology for the N-terminal salivary glycoprotein-binding region. Almost all of the sera from patients with rheumatic disease reacted strongly with SR from S. mutans serotype f, P1 from S. mutans serotype c, and four peptides located in the hIgG-cross-reacting region and not with peptides located at the C and N termini and in the proline-rich repeats. These results confirm that epitopes located within this region are immunogenic in humans and could lead to the synthesis of natural anti-IgG antibodies.     

Rapid neurofibrillary tangle formation after localized gene transfer of mutated tau

Neurofibrillary pathology was produced in the brains of adult rats after localized gene transfer of human tau carrying the P301L mutation, which is associated with frontotemporal dementia with parkinsonism. Within 1 month of in situ transfection of the basal forebrain region of normal rats, tau-immunoreactive and argyrophilic neuronal lesions formed. The fibrillar lesions had features of neurofibrillary tangles and tau immunoreactivity at light and electron microscopic levels. In addition to neurofibrillary tangles, other tau pathology, including pretangles and neuropil threads, was abundant and widespread. Tau gene transfer to the hippocampal region of amyloid-depositing transgenic mice produced pretangles and threads, as well as intensely tau-immunoreactive neurites in amyloid plaques. The ability to produce neurofibrillary pathology in adult rodents makes this a useful method to study tau-related neurodegeneration.     

Mental fatigue and task control: planning and preparation

The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by "time on task," with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a new task set was required on every second trial. Manipulations of response-stimulus intervals (RSIs) were used to examine whether subjects prepared themselves for the task change. Behavioral measurements, event-related potentials (ERPs), and mood questionnaires were used to assess the effects of mental fatigue. Reaction times (RTs) were faster on trials in which no change in task set was required in comparison with switch trials, requiring a new task set. Long RSIs were used efficiently to prepare for the processing of subsequent stimuli. With increasing mental fatigue, preparation processes seemed to become less adequate and the number of errors increased. A clear poststimulus parietal negativity was observed on repetition trials, which reduced with time on task. This attention-related component was less pronounced in switch trials; instead, ERPs elicited in switch trials showed a clear frontal negativity. This negativity was also diminished by time on task. ERP differences between repetition and switch trials became smaller with increasing time on task.