523 research outputs found
Über das ungewöhnliche Schmelzverhalten von Mischungen aus Homoadamantan-1- und -3-carbonsäure
Transmembrane Adaptor Proteins Positively Regulating the Activation of Lymphocytes
Engagement of the immunoreceptors initiates signaling cascades resulting in lymphocyte activation and differentiation to effector cells, which are essential for the elimination of pathogens from the body. For the transduction of these immunoreceptor-mediated signals, several linker proteins termed transmembrane adaptor proteins (TRAPs) were shown to be required. TRAPs serve as platforms for the assembly and membrane targeting of the specific signaling proteins. Among seven TRAPs identified so far, LAT and LIME were shown to act as a positive regulator in TCR-mediated signaling pathways. In this review, we will discuss the functions of LAT and LIME in modulating T cell development, activation and differentiation
Ein neues, unkompliziert auszuführendes Verfahren zur Bestimmung kleiner Konzentrationen an Wasser in organischen Lösungsmitteln
A new procedure for the determination of water (even in trace amounts) in organic solvents is described. The solvatochromism of the pyridiniumphenol betaine, E T30, determined by a simple UV-absorption measurement, together with a two-parameter equation, permits an exact determination. The procedure is rapid and is, therefore, an alternative to the Karl-Fischer titration
Y-chromosomal variation in the Czech Republic
To analyze the contribution of the Czech population to the Y-chromosome diversity landscape of Europe and to reconstruct past demographic events, we typed 257 males from five locations for 21 UEPs. Moreover, 141 carriers of the three most common haplogroups were typed for 10 microsatellites and coalescent analyses applied. Sixteen Hg's characterized by derived alleles were identified, the most common being R1a-SRY10831 and P-DYS257*(xR1a). The pool of haplogroups within I-M170 represented the third most common clade. Overall, the degree of population structure was low. The ages for Hg I-M170, P-DYS257*(xR1a), and R1a-SRY10831 appeared to be comparable and compatible with their presence during or soon after the LGM. A signal of population growth beginning in the first millennium B.C. was detected. Its similarity among the three most common Hg's indicated that growth was characteristic for a gene pool that already contained all of them. The Czech population appears to be influenced, to a very moderate extent, by genetic inputs from outside Europe in the post-Neolithic and historical times. Population growth postdated the archaeologically documented introduction of Neolithic technology and the estimated central value coincides with a period of repeated changes driven by the development of metal technologies and the associated social and trade organization
Ein neues, unkompliziertes Verfahren zur Bestimmung der Zusammensetzung binärer Flüssigkeitsgemische
Ein neues Verfahren zur Bestimmung der Zusammensetzung binärer Flüssigkeitsgemische mit Hilfe solvatochromer Farbstoffe wird beschrieben. Die Analyse erfolgt durch einfache UV/VIS-Absorptionsmessung und ist unter Verwendung einer Zwei-Parameter-Gleichung ein exakter Schnelltest
Explicit Kundt type II and N solutions as gravitational waves in various type D and O universes
A particular yet large class of non-diverging solutions which admits a
cosmological constant, electromagnetic field, pure radiation and/or general
non-null matter component is explicitly presented. These spacetimes represent
exact gravitational waves of arbitrary profiles which propagate in background
universes such as Minkowski, conformally flat (anti-)de Sitter, Edgar-Ludwig,
Bertotti-Robinson, and type D (anti-)Nariai or Plebanski-Hacyan spaces, and
their generalizations. All possibilities are discussed and are interpreted
using a unifying simple metric form. Sandwich and impulsive waves propagating
in the above background spaces with different geometries and matter content can
easily be constructed. New solutions are identified, e.g. type D pure radiation
or explicit type II electrovacuum waves in (anti-)Nariai universe. It is also
shown that, in general, there are no conformally flat Einstein-Maxwell fields
with a non-vanishing cosmological constant.Comment: 17 pages, LaTeX 2e. v2: added two references concerning generalized
Kerr-Schild transformations, minor changes in the tex
A hypomorphic allele of ZAP-70 reveals a distinct thymic threshold for autoimmune disease versus autoimmune reactivity
ZAP-70 is critical for T cell receptor (TCR) signaling. Tyrosine to phenylalanine mutations of Y315 and Y319 in ZAP-70 suggest these residues function to recruit downstream effector molecules, but mutagenesis and crystallization studies reveal that these residues also play an important role in autoinhibition ZAP-70. To address the importance of the scaffolding function, we generated a zap70 mutant mouse (YYAA mouse) with Y315 and Y319 both mutated to alanines. These YYAA mice reveal that the scaffolding function is important for normal development and function. Moreover, the YYAA mice have many similarities to a previously identified ZAP-70 mutant mouse, SKG, which harbors a distinct hypomorphic mutation. Both YYAA and SKG mice have impaired T cell development and hyporesponsiveness to TCR stimulation, markedly reduced numbers of thymic T regulatory cells and defective positive and negative selection. YYAA mice, like SKG mice, develop rheumatoid factor antibodies, but fail to develop autoimmune arthritis. Signaling differences that result from ZAP-70 mutations appear to skew the TCR repertoire in ways that differentially influence propensity to autoimmunity versus autoimmune disease susceptibility. By uncoupling the relative contribution from T regulatory cells and TCR repertoire during thymic selection, our data help to identify events that may be important, but alone are insufficient, for the development of autoimmune disease
Determination of pH in Regions of the Midguts of Acaridid Mites
The pH of the guts of mites strongly affects their digestive processes. This study was carried out to determine the pH in the guts of 12 species of stored product and house dust mites. Eighteen pH indicators were chosen and offered to the mites in the feeding biotest. Based on the color changes of the indicators, the gut contents of acaridid mites were determined to be within a pH range of 4 to neutral. The gut contents showed a gradient in pH from the anterior to the posterior part. The anterior midgut (ventriculus and caeca) of most species had a pH ranging from 4.5 to 5, or slightly more alkaline for most of the species, while the middle midgut (intercolon/colon) had a pH of 5 to 6. Finally, the pH of the posterior midgut (postcolon) was between 5.5 and 7. Except for Dermatophagoides spp., no remarkable differences in the pH of the gut were observed among the tested species. Dermatophagoides spp. had a more acidic anterior midgut (a pH of 4 to 5) and colon (a pH of 5) with postcolon (a pH of below 6). The results characterizing in vivo conditions in the mite gut offer useful information to study the activity of mite digestive enzymes including their inhibitors and gut microflora
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