Rapid progression of aortic and mitral stenosis in a patient with AA amyloidosis: a case report

Background: Aortic stenosis is a common finding in cardiac amyloidosis (CA). Younger patients often remain asymptomatic. If unrecognized, this can lead to serious complications such as heart failure. Progression of aortic stenosis can be accelerated in patients with chronic kidney disease and need for dialysis. Perioperative risk in these patients is often high due to the underlying systemic disease. Case summary: A 40-year-old Caucasian man with known AA amyloidosis, highly active Ankylosing Spondylitis and need for chronic dialysis due to end-stage chronic renal failure presented for echocardiographic routine exam without reporting any cardiac symptoms. At the last visit 4 years ago, a normal heart valve function was noted and no echocardiographic follow-up was performed in the following. Now, rapid progression with severe aortic valve and mitral valve stenosis was stated and the patient underwent combined aortic and mitral surgical valve replacement following discussion in the multidisciplinary cardiology meeting. Macroscopic examination of the valves revealed significant calcification and histological examination showed the high presence of amyloid by Congo-red staining and immunohistological staining for AA-Amyloid. Both valve prosthetic devices showed normal function as well as a normal left ventricular ejection fraction in initial post-operative transoesophageal echocardiography. After prolonged and complicated post-operative course in the intensive care unit the patient died 3 months after surgery due to intractable multiorgan failure in combined severe abdominal septic and cardiogenic shock. Discussion: Concomitant CA and chronic dialysis can accelerate the onset of severe aortic valve stenosis. Young patients, as in this case, often stay asymptomatic, perioperative risk increases with duration of chronic dialysis and severity of valve stenosis. This increases the need for regular short-term echocardiographic examinations even in clinical stable patients

Continuous Attractors with Morphed/Correlated Maps

Continuous attractor networks are used to model the storage and representation of analog quantities, such as position of a visual stimulus. The storage of multiple continuous attractors in the same network has previously been studied in the context of self-position coding. Several uncorrelated maps of environments are stored in the synaptic connections, and a position in a given environment is represented by a localized pattern of neural activity in the corresponding map, driven by a spatially tuned input. Here we analyze networks storing a pair of correlated maps, or a morph sequence between two uncorrelated maps. We find a novel state in which the network activity is simultaneously localized in both maps. In this state, a fixed cue presented to the network does not determine uniquely the location of the bump, i.e. the response is unreliable, with neurons not always responding when their preferred input is present. When the tuned input varies smoothly in time, the neuronal responses become reliable and selective for the environment: the subset of neurons responsive to a moving input in one map changes almost completely in the other map. This form of remapping is a non-trivial transformation between the tuned input to the network and the resulting tuning curves of the neurons. The new state of the network could be related to the formation of direction selectivity in one-dimensional environments and hippocampal remapping. The applicability of the model is not confined to self-position representations; we show an instance of the network solving a simple delayed discrimination task

A Prehispanic Maya Katun Wheel

Much has been written on the calendrical achievements of the ancient Maya; however, little is known of the ancient Maya models for recording and conceiving of the passage of time. A carved stone turtle excavated at the site of Mayapan indicates that the Maya concept of circular calendar wheels is prehispanic in origin. Contextual information provided by archaeological excavation and representations in prehispanic Maya codices indicate that stone turtle sculptures were the locus of penitential blood offerings marking calendrical period endings, particularly that of the roughly twenty-year Katun. The ancient Maya had a number of distinct metaphors for conceiving of the world. Among both the Classic and Postclassic Maya, the turtle served as an important model of the rounded and circular earth

Functionalized capillaries for label- free bio-molecule-detection utilizing the streaming current method

This report aims to make a contribution in optimizing a bio-sensor which exploits the changes in streaming current in a fused silica capillary as target molecules bind to immobilized receptors on the inner surface of the capillary. In this study we investigate the temporal characteristics of the sensor response as a function of capillary-dimension for different concentrations of target biomolecules. Using Heceptine-z domain interaction pairs and silica capillaries with different inner diameters in the range of 25-55 µm and lengthin the range of 3-9 cm we show that the reduction in capillary cross-section re-sults in a faster sensor response. The results show qualitative agreement withan analytical model grounded on diffusion-based mass transport under laminar flow condition and offer possibility to achieve a lower limit of detection with thinner capillaries.Denna rapport bidrar i arbetet att optimera en biosensor baserad på den flödes-inducerade elektriska strömmen som uppstår i en glaskapillär där målmolekyler i en lösning binder till immobiliserade receptorer på den inre ytan av kapillären. I experimenten som här presenteras har tidsberoendet hos sen-sorsvaret undersökts för olika koncentrationer av målmolekylen, från 10 nm till 1 nm. Interaktionsparet (Immuglobin 1G och antikropp)(Heceptine-z) användes i dessa experiment och med att testa olika glaskapillärer med innerdiametrar i intervallet 25 till 55 µm, samt längd mellan 3 och 9 cm, visar vi att en minskning av innerdiametern resulterar i snabbare sensorsvar. Resultaten visar påen kvalitativ överrenstämmelse med en analytisk modell grundad i diffusionsbaserad masstransport med krav på laminärt flöde. Denna modell tyder på att det är möjligt att detektera lägre koncentrationen med tunnare kapillärer än vad här har testats