886 research outputs found
Hyperostotic tympanic bone spicules in domestic and wild animal species
Hyperostotic tympanic bone spicules (HTBS), or "mucoperiosteal exostoses" (ME, syn.) are small, globular (>= 1 mm in diameter), mostly stalked and drumstick-like, bony structures, which arise from the inner wall of the tympanic bulla and project into the middle ear cavity. HTBS present as mineral densities inside the tympanic bulla on radiographs or computed tomographic (CT) images. They have previously been referred to as "otoliths" and were thought to represent mineral concretions secondary to otitis media. Recently, it was shown that HTBS actually consist of regularly composed bone tissue, covered by normal middle ear mucosa. So far, HTBS have only extensively been described in dogs, where they occur with a prevalence of up to >45%. A recent study detected ME, most likely representing HTBS, in the tympanic cavities of skeletonised skull bones of African lions. To estimate the occurrence of HTBS in other mammal species, the middle ears of adult animals of 78 different domestic, wild, and zoo species undergoing routine necropsy at the Institute of Veterinary Pathology of the LMU Munich, Germany were examined in the present study. HTBS were found in the tympanic bullae of carnivorous species, such as canids (wolf, fox), and in several large felid species (lion, tiger, leopard, cheetah). In contrast, HTBS were not present in domestic cats (more than to 200 cases), small carnivorous species such as mustelids, nor in any primate, ungulate, ruminant, pig, insectivore, or rodent species. The detectability of HTBS by CT of the tympanic bullae of large felids was demonstrated in an African lion. Histologically, HTBS consisted of mature lamellar bone, covered by periosteum and a partially ciliated, flat epithelium, regularly without any apparent inflammatory alterations. The present study demonstrates that HTBS may frequently occur in large felids and in different canid species. These findings should be taken into account when examining the middle ear, or interpreting bulla radiographs/CT-images of the respective species. However, the factors triggering the development of HTBS remain to be identified
Bedeutung bakterieller Superantigene und der T-Zell Rezirkulation in die Haut fĂŒr das Hautimmunsystem
T-Zellen spielen bei der ImmunĂŒberwachung der peripheren Organe wie der Haut eine zentrale Rolle. Sie wandern als naive T-Zellen kontinuierlich in groĂer Zahl in den Paracortex der peripheren Lymphknoten ein. Die Lymphknoten dienen der Konzentration von antigenem Material, das in der Periphere von professionellen Antigen-prĂ€sentierenden Zellen aufgenommen und in die Lymphknoten transportiert wird. Dort treten die Antigen-prĂ€sentierenden Zellen in engen, physischen Kontakt mit naiven, Antigen-spezifischen T-Zellen und aktivieren diese. Neben der Aktivierung in diesem definierten anatomischen Kontext kommt es auch zur Aufregulation eines Codes spezifischer AdhĂ€sionsmolekĂŒle, die die Invasion in dasjenige Organ zur Folge hat, aus dem das Antigen drainiert wurde. Dieses organspezifische Rezirkulationsverhalten wird âHomingâ genannt und hat eine optimierte Antigenabwehr zur Folge, da unterschiedliche Antigene typischer Weise mit unterschiedlicher Frequenz in verschiedenen Organen anzutreffen sind. .... Ziel des ersten Teils der Arbeit war es somit, Auslöser der genannten entzĂŒndlichen Dermatosen molekular zu charakterisieren. Ausgehend von der klinischen Beobachtung, daĂ bakterielle Infektionen bzw. Besiedelung mit Gram-positiven Erregern diesen Erkrankungen vorangehen, wollten wir die Bedeutung von bakteriellen Superantigenen nĂ€her untersuchen, da diese Substanzen aufgrund ihrer starken, T-Zell stimulierenden Eigenschaften als KandidatenmolekĂŒle fĂŒr die Induktion von T-Zell mediierten Dermatosen in Frage kamen. Dazu etablierten wir fĂŒr die Psoriasis vulgaris ein xenogenes Transplantationsmodell. Bei diesem wurde humane Haut von gesunden Kontrollen oder perilĂ€sionale Haut von Patienten mit Psoriasis vulgaris auf immundefiziente SCID-MĂ€use transplantiert. Die repetitive Injektion eines bakteriellen Superantigens induzierte ausschlieĂlich bei Psoriatikern, nicht jedoch bei gesunden Kontrollen, einen psoriatischen PhĂ€notyp. Diese Ergebnisse lassen zwei SchlĂŒsse zu: (I) Ein bakterielles Superantigen ist unter bestimmten Voraussetzungen ausreichend, um eine Psoriasis zu induzieren. (II) Ein bestimmtes, evt. genetisch determiniertes Mikromilieu der Haut ist Voraussetzung fĂŒr die Induktion der Psoriasis durch das Superantigen. ... Im zweiten Teil der Arbeit gingen wir der Frage nach, inwiefern VerĂ€nderungen des Hautimmunsystems nachweisbar sind, die auf bakterielle Superantigene zurĂŒckzufĂŒhren sind. In unseren Untersuchungen setzten wir dabei zwei Schwerpunkte: (I) Das T-Zell Rezeptor (TCR) Vbeta Repertoire, da Superantigene alpha/beta+ T-Zellen in TCR Vbeta spezifischer Weise aktivieren und (II) AdhĂ€sionsmolekĂŒle unter besonderer BerĂŒcksichtigung des Haut-spezifischen AdhĂ€sionsmolekĂŒls CLA, da T-Zell AdhĂ€sionsmolekĂŒle aktivierungsabhĂ€ngig reguliert werden und eine verĂ€nderte T-Zell Migration in pathophysiologische VorgĂ€nge involviert ist. Die Untersuchungen des TCR Vbeta Repertoires der Haut erfolgten an der Psoriasis vulgaris als Modell einer T-Zell vermittelten Immundermatose, die â wie oben gezeigt â u.a. durch bakterielle Superantigene induziert werden kann. Im Gegensatz zu Untersuchungen zur âakutenâ Form der Psoriasis, der Psoriasis guttata, bei der Superantigen-mediierte VerĂ€nderungen des TCR Vbeta Repertoires der Haut im Vergleich zum Blut nachgewiesen werden konnten, fanden wir und auch andere Arbeitsgruppen bei der chronisch-stationĂ€ren Form der Psoriasis keine VerĂ€nderungen des TCR Vbeta Repertoires der Haut, das fĂŒr einen Superantigen-mediierten Effekt spricht. Aus diesen und anderen Befunden entwickelten wir ein pathophysiologisches Konzept der Psoriasis, bei dem Superantigene zwar in die Induktion, nicht jedoch in die Aufrechterhaltung des Erkrankungsprozesses involviert sind. ..
Spatial risk modeling of cattle depredation by black vultures in the midwestern United States
ock operations through depredation of stock are a cause of humanâwildlife conflict. Management of such conflict requires identifying environmental and nonâenvironmental factors specific to a wildlife species\u27 biology and ecology that influence the potential for livestock depredation to occur. Identification of such factors can improve understanding of the conditions placing livestock at risk. Black vultures (Coragyps atratus) have expanded their historical range northward into the midwestern United States. Concomitantly, an increase in concern among agricultural producers regarding potential black vulture attacks on livestock has occurred. We estimated area with greater or lesser potential for depredation of domestic cattle by black vultures across a 6âstate region in the midwestern United States using an ensemble of small models (ESM). Specifically, we identified landscapeâscale spatial factors, at a zip code resolution, associated with reported black vulture depredation on cattle in midwestern landscapes to predict future potential livestock depredation. We hypothesized that livestock depredation would be greatest in areas with intensive beef cattle production close to preferred black vulture habitat (e.g., areas with fewer old fields and early successional vegetation paired with more direct edge between older forest and agricultural lands). We predicted that the density of cattle within the county, habitat structure, and proximity to anthropogenic landscape features would be the strongest predictors of black vulture livestockâdepredation risk. Our ESM estimated the relative risk of black vultureâcattle depredation to be between 0.154â0.631 across our entire study area. Consistent with our hypothesis, areas of greatest predicted risk of depredation correspond with locations that are favorable to vulture lifeâhistory requirements and increased potential to encounter livestock. Our results allow wildlife managers the ability to predict where black vulture depredation of cattle is more likely to occur in the future. It is in these areas where extension and outreach efforts aimed at mitigating this conflict should be focused. Researchers and wildlife managers interested in developing or employing tools aimed at mitigating livestockâvulture conflicts can also leverage our results to select areas where depredation is most likely to occur
Assessing the influence of socials calls on bat mist-netting success in North America
Since the introduction of the fungal disease White-Nose Syndrome in 2006, millions of North American bats have perished. For many species, the disease has caused over a 90 percent decline in abundance. With populations fluctuating as the pathogen spreads, biologists require improved methods of estimating bat demographics and abundance. Previous research indicates that mist netting success may be improved with the use of acoustic lures at mist-netting locations. Our research investigates which type of social calls improve the capture rates of North American bats, including the big brown bat (Eptesicus fuscus). Social call types used include antagonistic buzzes, distress calls, advertising calls, mother-to-offspring calls, and cohesion calls. We deployed acoustic lures at each netting site from 15 May 2017 to 15 August 2017. We created 5-hour long playlists using 10-minute blocks of each of the 5 call types, including a block of silence as control. We recorded the time of each bat capture to indicate the call block each individual entered the net. We utilized maximum likelihood analysis in program R to identify if call type had an influence on bat captures. Analysis indicated that European distress calls negatively impacted big brown bat captures. Overall, this suggests that researchers should utilize North American bat calls to improve capture rates of big brown bats
Analysis of the multiplication of D-T neutron sources in blanket materials of fusion reactors
Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing
Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and
four-wave mixing (FWM) experiments were performed simultaneously to study the
initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats
between the A-B excitons were found \textit{only for positive time delay} in
both PP and FWM experiments. The rise time at negative time delay for the
differential reflection spectra was much slower than the FWM signal or PP
differential transmission spectroscopy (DTS) at the exciton resonance. A
numerical solution of a six band semiconductor Bloch equation model including
nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS
results from excitation induced dephasing (EID), that is, the strong density
dependence of the dephasing time which changes with the laser excitation
energy.Comment: 8 figure
Polyglycerol-based amphiphilic dendrons as potential siRNA carriers for in vivo applications
The development of nonviral synthetic vectors for clinical application of gene
therapy using siRNA transfection technology is of particular importance for
treatment of human diseases, which is yet an unsolved challenge. By employing
a rational design approach, we have synthesized a set of well-defined, low-
molecular-weight dendritic polyglycerol-based amphiphiles, which are decorated
peripherally with the DAPMA (N,N-di-(3-aminopropyl)-N-(methyl)amine) moiety.
The main differences that were introduced in the structural motif relate to
dendron generation and the type of linker between the hydrophilic and
hydrophobic segment. The synthesized amphiphiles were then characterized for
their aggregation behaviour and further evaluated with respect to their siRNA
transfection potential by comparing their physico-chemical and biological
features. Our findings demonstrated that all four synthesized amphiphiles
yielded high gene binding affinities. Furthermore, the ester-linked compounds
(G1-Ester-DAPMA, G2-Ester-DAPMA) revealed noticeable gene silencing in vitro
without affecting the cell viability in the tumor cell line 786-O. Remarkably,
neither G1-Ester-DAPMA nor G2-Ester-DAPMA induced inflammatory side effects
after systemic administration in vivo, which is noteworthy because such highly
positively charged compounds are typically associated with toxicity concerns
which in turn supports their prospective application for in vivo purposes.
Therefore, we believe that these structures may serve as new promising
alternatives for nonviral siRNA delivery systems and have great potential for
further synthetic modifications
Decreased expression of breast cancer resistance protein in the duodenum in patients with obstructive cholestasis
Background/Aims: The expression of transporters involved in bile acid homeostasis is differentially regulated during obstructive cholestasis. Since the drug efflux transporter breast cancer resistance protein (BCRP) is known to transport bile acids, we investigated whether duodenal BCRP expression could be altered during cholestasis. Methods: Using real-time RT-PCR analysis we determined mRNA expression levels in duodenal tissue of 19 cholestatic patients. Expression levels were compared to 14 healthy subjects. BCRP protein staining was determined in biopsies of 6 cholestatic and 6 healthy subjects by immunohistochemistry. Results: We found that in patients with obstructive cholestasis mean duodenal BCRP mRNA levels were significantly reduced to 53% and mean protein staining was reduced to 57%. Conclusions: BCRP, a transporter for bile acids and numerous drugs, appears to be down-regulated in the human duodenum during cholestasis. The clinical impact of these results has to be investigated in further studies. Copyright (c) 2006 S. Karger AG, Basel
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