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.     

Identification of surface-exposed B-cell epitopes recognized by Haemophilus influenzae type b P1-specific monoclonal antibodies.

A panel of P1 synthetic peptides was synthesized to map the surface-exposed epitopes of Haemophilus influenzae type b outer membrane protein P1 recognized by three murine monoclonal antibodies (MAbs 7C8, 3E12, and 6B1). By using peptide-specific enzyme-linked immunosorbent assays, MAbs 6B1, 7C8, and 3E12 were shown to recognize distinct epitopes localized within residues 60 to 88, 165 to 193, and 400 to 437 of mature P1, respectively. Since MAb 7C8 was shown previously to be protective against certain H. influenzae type b subtypes in the infant rat model of bacteremia, its cognate epitope was further characterized by using truncated peptide analogs. Fine mapping of the 7C8 epitope by competitive inhibition studies revealed that it was localized within residues 184 and 193.     

Role for mannose binding lectin in the prevention of Mycoplasma infection

Polymorphisms in exon 1 of the MBL-2 gene, resulting in reduced plasma levels of mannose binding lectin, were significantly overrepresented in 23 patients with primary antibody deficiency and culture-proven mycoplasma infections (P = 0.0038). This association persisted with the inclusion of a further nine suspected (doxycycline-responsive) cases (P = 0.0087). The lectin was shown to bind to three strains of mycoplasma.     

Correlation of viscoelastic properties with the molar mass distribution for aqueous polyacrylamide solutions

The dependence of viscous and elastic rheological functions on molar mass and molar mass distribution was investigated under shear flow conditions using concentrated solutions of polyacrylamides and polyacrylamide mixtures. The zero-shear viscosity η₀ correlates with the weight-average molar mass M?_w; with increasing shear rate the corresponding controlling molar mass average tends to change to the number-average molar mass M?_n. It is shown that the analysis of the shape of the whole flow curve is a simple way to obtain qualitative information about molar mass distribution. Elastic forces are influenced mainly by the high-molar-mass tail of a molar mass distribution. The zero normal stress coefficient ψ₀ depends on a molar mass average between M?_w and z-average molar mass M?_z·ψ₀ increases with the 7,4th power of the molar mass for the polyacrylamides (not for the mixtures). The steady-state compliance J_e⁽⁰⁾ is, for the investigated system, independent of the absolute molar mass, but increases with the 5,5th power of the ratio M?_z/M?_w. The elasticity modulus G₀^(A) can be correlated with M?_n of the polyacrylamide samples and their mixtures. These investigations show that the analysis of various rheological functions can lead to a wealth of information about the molar mass distribution of a polymer.     

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.     

Expression of Ia and monocyte-macrophage lineage antigens in giant cell tumor of bone and related lesions

An immunohistochemical study of six giant cell tumors of bone and eight related lesions (aneurysmal bone cyst, fibrous histiocytoma, and giant cell tumor of tendon sheath) was performed using a panel of monoclonal antibodies directed to the Ia and monocyte-macrophage lineage antigens. In all types of lesion, osteoclastlike multinucleate giant cells were negative for both types of antigen, but a proportion of mononuclear cells gave positive reactions. While the possibility that these cells are reactive cannot be excluded, in giant cell tumor and malignant fibrous histiocytoma, their frequency and their morphologic similarity to the rest of the tissue suggest that they may be an intrinsic part of the neoplasm. This finding is consistent with the presumed fibrohistiocytic nature of these tumors.     

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.