Einfluss verschiedener Abutmentmaterialien und der adhäsiven Verbindung von zweiteiligen Abutments auf das periimplantäre Gewebe

Abutments haben maßgeblich Einfluss auf den zervikalen Implantatknochen und das periimplantäre Weichgewebe. Die Wahl des Materials kann zudem das ästhetische Ergebnis einer Implantatversorgung signifikant beeinflussen. In der Literatur finden sich wenige Daten über Vergleiche von zweiteiligen Zirkoniumdioxid- und Lithiumdisilikatabutments mit Titanabutments. Auch der Einfluss der Klebeverbindung zweiteili-ger Abutments ist bisher wenig erforscht. Ziel dieser Studie war es daher, den Einfluss unterschiedlicher Abutmentmaterialien und der adhäsiven Verbindung von zweiteiligen Abutments auf das periimplantäre Gewebe anhand von osseointegrierten Implantaten (Camlog Biotechnologies, Basel, Schweiz) an vier Minischweinen zu untersuchen. Dazu wurden den Versuchstieren zunächst alle Prämolaren sowie die ersten Molaren in allen vier Quadranten entfernt. Nach einer Ausheilungszeit von drei Monaten wurden jedem Tier vier Implantate pro Quadrant inseriert. Drei Monate später wurde der Implantat-Stabilitäts-Quotient (ISQ) mittels Resonanzfrequenzanalyse (RFA) gemessen und die Implantate mit jeweils vier unterschiedlichen Abutments pro Quadrant versehen. Getestete Abutments wa-ren: - Zirkoniumdioxid auf Titanklebebasis (zweiteilig) - Lithiumdisilikat auf Titanklebebasis (zweiteilig) - Titan auf Titanklebebasis (zweiteilig) - Titan (einteilig) Nach Eingliederung der Abutments bekamen die Versuchstiere alle zwei Wochen unter Sedierung eine professionelle Zahn- und Implantatreinigung. Weiterhin wurden fortlaufend Fluoreszenzfarbstoffe (Xylenol-Orange, Calcein-Grün und Tetrazyklin-Hydrochlorid) injiziert. Sechs Monate später wurden die Versuchstiere getötet und die entnommenen Präparate histomorphometrisch im Lichtmikroskop hinsichtlich KIK (Knochen-Implantat-Kontakt), S (Sulkustiefe), SE (Saumepithel), BG (Bindegewebe), BB (Biologische Breite) und EZKIKIS (erster zervikaler Knochen-Implantat-Kontakt–Implantatschulter) vermessen sowie visuell im Fluoreszenzmikroskop untersucht. 50 Implantate (78 %) waren osseointegriert und konnten ausgewertet werden. KIK betrug durchschnittlich 61±23 % und ISQ 77±4. Die verschiedenen Abutmentmaterialien und die adhäsive Verbindung hatten keinen signifikanten Einfluss auf das periimplantäre Weichgewebe (P>0,05), mit Ausnahme des Saumepithels an zweiteiligen Zirkoniumdioxid- und einteiligen Titanabutments. Im Oberkiefer zeigten sich signifikant mehr Weichgewebe und weniger Knochenverlust als im Unterkiefer (P≤0,02). Bei der visuellen Auswertung der Bilder der Fluoreszenzmikroskopie konnten keine Unterschiede zwischen den Abutments festgestellt werden. Zusammenfassend konnte in dieser Studie gezeigt werden, dass, im Hinblick auf die Weichgewebeeigenschaften und den zervikalen Knochen, alle getesteten Abutmentmaterialien und Abutmenttypen für eine prothetische Versorgung von Zahnimplantaten geeignet scheinen

A dual role for prediction error in associative learning

Confronted with a rich sensory environment, the brain must learn statistical regularities across sensory domains to construct causal models of the world. Here, we used functional magnetic resonance imaging and dynamic causal modeling (DCM) to furnish neurophysiological evidence that statistical associations are learnt, even when task-irrelevant. Subjects performed an audio-visual target-detection task while being exposed to distractor stimuli. Unknown to them, auditory distractors predicted the presence or absence of subsequent visual distractors. We modeled incidental learning of these associations using a Rescorla--Wagner (RW) model. Activity in primary visual cortex and putamen reflected learning-dependent surprise: these areas responded progressively more to unpredicted, and progressively less to predicted visual stimuli. Critically, this prediction-error response was observed even when the absence of a visual stimulus was surprising. We investigated the underlying mechanism by embedding the RW model into a DCM to show that auditory to visual connectivity changed significantly over time as a function of prediction error. Thus, consistent with predictive coding models of perception, associative learning is mediated by prediction-error dependent changes in connectivity. These results posit a dual role for prediction-error in encoding surprise and driving associative plasticity

Ordering effect of Coulomb interaction in ballistic double-ring systems

We study a model of two concentric onedimensional rings with incommensurate areas $A_1$ and $A_2$, in a constant magnetic field. The two rings are coupled by a nonhomogeneous inter-ring tunneling amplitude, which makes the one-particle spectrum chaotic. For noninteracting particles the energy of the many-body ground state and the first excited state exhibit random fluctuations characterized by the Wigner-Dyson statistics. In contrast, we show that the electron-electron interaction orders the magnetic field dependence of these quantities, forcing them to become periodic functions, with period $\propto 1/(A_1 + A_2)$. In such a strongly correlated system the only possible source of disorder comes from charge fluctuations, which can be controlled by a tunable inter-ring gate voltage.Comment: 4 pages, 4 eps figures, revised text and new figures (as published

Brevibacterium from Austrian hard cheese harbor a putative histamine catabolism pathway and a plasmid for adaptation to the cheese environment

The genus Brevibacterium harbors many members important for cheese ripening. We performed real-time quantitative PCR (qPCR) to determine the abundance of Brevibacterium on rinds of Vorarlberger Bergkäse, an Austrian artisanal washed-rind hard cheese, over 160 days of ripening. Our results show that Brevibacterium are abundant on Vorarlberger Bergkäse rinds throughout the ripening time. To elucidate the impact of Brevibacterium on cheese production, we analysed the genomes of three cheese rind isolates, L261, S111, and S22. L261 belongs to Brevibacterium aurantiacum, whereas S111 and S22 represent novel species within the genus Brevibacterium based on 16S rRNA gene similarity and average nucleotide identity. Our comparative genomic analysis showed that important cheese ripening enzymes are conserved among the genus Brevibacterium. Strain S22 harbors a 22 kb circular plasmid which encodes putative iron and hydroxymethylpyrimidine/thiamine transporters. Histamine formation in fermented foods can cause histamine intoxication. We revealed the presence of a putative metabolic pathway for histamine degradation. Growth experiments showed that the three Brevibacterium strains can utilize histamine as the sole carbon source. The capability to utilize histamine, possibly encoded by the putative histamine degradation pathway, highlights the importance of Brevibacterium as key cheese ripening cultures beyond their contribution to cheese flavor production

Prevalence and Correlates of Depressive Symptoms in a Community Sample of People Suffering from Heart Failure

To examine the rates and correlates of depressive symptoms and syndromal depression in people with self-reported heart failure participating in a community study of people aged 70 and older. DESIGN: Cross-sectional. SETTING: Community-based epidemiological study of older people from the continental United States. PARTICIPANTS: Six thousand one hundred twenty-five older people participating in the longitudinal study of Assets and Health Dynamics. Participants had to be born in 1923 or earlier. MEASUREMENTS: The short-form Composite International Diagnostic Interview assessed syndromal depression, and a revised version of the Center for Epidemiologic Studies—Depression scale assessed depressive symptoms. Medical illness was based on self-report. The authors compared the rates of syndromal depression and individual depressive symptoms in people with self-reported heart failure (n = 199) with those in people with other heart conditions (n = 1,856) and with no heart conditions (n = 4,070). RESULTS: Eleven percent of those with heart failure met criteria for syndromal depression, compared with 4.8% of people with other heart conditions and 3.2% of those with no heart conditions. The association between heart failure and depression held even after controlling for disability, reported fatigue and breathlessness, and number of comorbid chronic illnesses. CONCLUSION: Community-living older people with self-reported heart failure were at approximately twice the risk for syndromal depression of the rest of the community. Although fatigue and functional disability were also related to depression in this sample, these variables did not account for the association between syndromal depression and self-reported heart failure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66305/1/j.1532-5415.2002.50612.x.pd

Memory Complaint in a Community Sample Aged 70 and Older

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111116/1/j.1532-5415.2000.tb02634.x.pd