Publications by authors named "Hepp K"

In diabetes prevention and care, invasiveness of glucose measurement impedes efficient therapy and hampers the identification of people at risk. Lack of calibration stability in non-invasive technology has confined the field to short-term proof of principle. Addressing this challenge, we demonstrate the first practical use of a Raman-based and portable non-invasive glucose monitoring device used for at least 15 days following calibration.

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Background: Noninvasive glucose monitoring (NIGM) in diabetes is a long-sought-for technology. Among the many attempts Raman spectroscopy was considered as the most promising because of its glucose specificity. In this study, a recently developed prototype (GlucoBeam, RSP Systems A/S, Denmark) was tested in patients with type 1 diabetes to establish calibration models and to demonstrate proof of concept for this device in real use.

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Reading is a highly complex task involving a precise integration of vision, attention, saccadic eye movements, and high-level language processing. Although there is a long history of psychological research in reading, it is only recently that imaging studies have identified some neural correlates of reading. Thus, the underlying neural mechanisms of reading are not yet understood.

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Synapses can only be morphologically identified by electron microscopy and this is often a very labor-intensive and time-consuming task. When quantitative estimates are required for pathways that contribute a small proportion of synapses to the neuropil, the problems of accurate sampling are particularly severe and the total time required may become prohibitive. Here we present a sampling method devised to count the percentage of rarely occurring synapses in the neuropil using a large sample (approximately 1000 sampling sites), with the strong constraint of doing it in reasonable time.

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Background: Sirolimus (SRL) is an immunosuppressive drug increasingly used in children undergoing solid organ transplantation. SRL does not cause glucose intolerance, hypertension, nephrotoxicity or neurotoxicity offering significant potential advantages over calceneurin inhibitors (CM).

Aim: To report five children treated with SRL.

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The cortical control of eye movements is highly sophisticated. Not only can eye movements be made to the most salient target in a visual scene, but they can also be controlled by top-down rules as is required for visual search or reading. The cortical area called frontal eye fields (FEF) has been shown to play a key role in the visual to oculomotor transformations in tasks requiring an eye movement pattern that is not completely reactive, but follows a previously learned rule.

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We present a neuromorphic pattern generator for controlling the walking gaits of four-legged robots which is inspired by central pattern generators found in the nervous system and which is implemented as a very large scale integrated (VLSI) chip. The chip contains oscillator circuits that mimic the output of motor neurons in a strongly simplified way. We show that four coupled oscillators can produce rhythmic patterns with phase relationships that are appropriate to generate all four-legged animal walking gaits.

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We report a 42 years old female that presented with abdominal pain and no palpable mass. Imaging abdominal ultrasound, CAT scan and magnetic resonance showed a solid tumor located in the retroperitoneum. The patient was operated on excising the tumor.

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While much is now known about the operation and organisation of the brain at the neuronal and microcircuit level, we are still some way from understanding it as a complete system from the lowest to the highest levels of description. One way to gain such an integrative understanding of neural systems is to construct them. We have built the largest neuromorphic system yet known, an interactive space called 'Ada' that is able to interact with many people simultaneously using a wide variety of sensory and behavioural modalities.

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There is strong anatomical and physiological evidence that neurons with large receptive fields located in higher visual areas are recurrently connected to neurons with smaller receptive fields in lower areas. We have previously described a minimal neuronal network architecture in which top-down attentional signals to large receptive field neurons can bias and selectively read out the bottom-up sensory information to small receptive field neurons (Hahnloser, Douglas, Mahowald, & Hepp, 1999). Here we study an enhanced model, where the role of attention is to recruit specific inter-areal feedback loops (e.

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We examined three-dimensional binocular positions in the alert and sleepy monkeys. In contrast to the tightly yoked eye movements observed in alertness, the eyes were usually converged, vertically misaligned and had a much larger torsional variability during light sleep. While in alertness eye position vectors were confined to fronto-parallel planes, the corresponding planes were rotated temporally (e.

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Saccade-related burst neurons in the paramedian pontine reticular formation (PPRF) of the head-restrained monkey provide a phasic velocity signal to extraocular motoneurons for the generation of rapid eye movements. In the superior colliculus (SC), which directly projects to the PPRF, the motor command for conjugate saccades with the head restrained in a roll position is represented in a reference frame in between oculocentric and space-fixed coordinates with a clear bias toward gravity. Here we studied the preferred direction of premotor burst neurons in the PPRF during static head roll to characterize their frame of reference with respect to head and eye position.

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Education programs for intensive insulin therapy were found to be valuable in improving glycemic control, but, due to low prevalence of type 1 diabetes in children and adolescents, access to those programs varies considerably in rural areas. We report on a telemedical care program that overcomes geographical isolation of patients on intensive insulin therapy. Sixty-one children and adolescents under the age of 26 participated in a telemedical care program.

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We examined three-dimensional eye positions in alertness and light sleep when monkeys were placed in different roll and pitch body orientations. In alertness, eye positions were confined to a fronto-parallel (Listing's) plane, torsional variability was small and static roll or pitch induced a torsional shift or vertical rotation of these planes. In light sleep, the planes rotated temporally by about 10 degrees, torsional variability increased by a factor of two and the static otolith-ocular reflexes were reduced by about 70%.

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The term insulin resistance includes both physiological and pathological metabolic changes. Physiological insulin resistance, for example, is to be found in puberty or in advanced old age; additionally, it may be caused by endocrinological diseases. A pathologically elevated insulin requirement is to be found in the insulin resistance syndrome, type A (genetic) or type B (insulin receptor antibodies).

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Objective: The importance of screening for diabetic retinopathy has been established, but the best method for screening has not yet been determined. We report on a trial of assessment of digital photographs by telemedicine compared with standard retinal photographs of the same fields and clinical examination by ophthalmologists.

Research Design And Methods: A total of 129 diabetic inpatients were screened for diabetic retinopathy by slit-lamp biomicroscopy performed by an ophthalmologist and by two-field 50 degrees non-stereo digital fundus photographs assessed by six screening centers that received the images by electronic mail.

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Neural networks combining local excitatory feedback with recurrent inhibition are valuable models of neocortical processing. However, incorporating the attentional modulation observed in cortical neurons is problematic. We propose a simple architecture for attentional processing.

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The rotation axis for each of the six extraocular muscles was determined in four eyes from three perfused rhesus monkeys. Measurements of the locations of muscle insertions and origins were made in the stereotaxic reference frame with the x-y plane horizontal and the x-z plane sagittal. The computed rotation axes of the horizontal recti were close to being in the x-z plane at an angle of about 15 degrees to the z axis.

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The positive influence of simultaneous pancreas and kidney transplantation (PKT) on the development of diabetic microvascular lesions is well established. On the other hand, little is known on its impact on diabetic macrovascular disease, which is still the major cause of death in diabetes, including patients after PKT. In order to evaluate the influence of PKT on the cardiovascular risk profile, we performed a cross-sectional study on 55 patients.

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Simultaneous pancreas and kidney transplantation (PKT) is associated with a deterioration of hemorheology. We investigated the determinants of plasma and blood viscosity (hct. 35%) after PKT (n = 49), in type 1 diabetes (n = 26) and in healthy controls (n = 24).

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This paper investigates the influence of static head tilt on the relation between activity in the motor layers of the superior colliculus (mSC) and saccadic oculomotor output. Based on single-unit recordings and electrical microstimulation in awake rhesus monkeys, we report that head roll changes the direction of the saccade vector generated by the mSC, with respect to a head-fixed coordinate system. Typically, the vector rotates in a direction that is opposite to the head roll direction.

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Plasma viscosity is mainly determined by large non-spherical proteins. In Type 1 diabetes mellitus, plasma viscosity increases with deterioration of diabetic control. Since protein glycation and formation of advanced glycosylation end products (AGEs) alter the structural and functional properties of proteins, AGEs might influence the rheological properties of plasma proteins.

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