The perception of body orientation after neck-proprioceptive stimulation

Different sensory systems (e.g. proprioception and vision) have a combined influence on the perception of body orientation, but the timescale over which they can be integrated remains unknown. Here we examined how visual information and neck proprioception interact in perception of the "subjective straight ahead" (SSA), as a function of time since initial stimulation. In complete darkness, healthy subjects directed a laser spot to the point felt subjectively to be exactly straight ahead of the trunk. As previously observed, left neck muscle vibration led to a disparity between subjective perception and objective position of the body midline, with SSA misplaced to the left. We found that this displacement was sustained throughout 28 min of continuous proprioceptive stimulation, provided there was no visual input. Moreover, prolonged vibration of neck muscles leads to a continuing disparity between subjective and objective body orientation even after offset of the vibration; the longer the preceding vibration, the more persistent the illusory deviation of body orientation. To examine the role of vision, one group of subjects fixated a central visual target at the start of each block of continuous neck vibration, with SSA then measured at successive intervals in darkness. The illusory deviation of SSA was eliminated whenever visual input was provided, but returned as a linear function of time when visual information was eliminated. These results reveal: the persistent effects of neck proprioception on the SSA, both during and after vibration; the influence of vision; and integration between incoming proprioceptive information and working memory traces of visual information.     

Ocular exploration of space as a function of neck proprioceptive and vestibular input — observations in normal subjects and patients with spatial neglect after parietal lesions

We recently argued that the specific compensation of spatial neglect by manipulating neck proprioceptive and vestibular input is due to a central correction of the disturbed neural transformation process converting the afferent input coordinates from the peripheral sensory organs into a central representation of egocentric space. Both types of stimulation were proposed to induce a reorientation of the deviated or distorted egocentric spatial reference frame. The aim of the present study was to observe this process of reorientation under a condition in which no visual stimulus can attract the subject's attention and thus influence exploration behaviour from outside. We recorded eye movements of normal subjects and of three patients with spatial neglect after right parietal lesions while searching for a non-existent target in complete darkness. It was assumed that the area of the outer space that subjects spontaneously explore under this condition is a direct function of the subject's representation of egocentric space. Ocular space exploration was biased and confined almost entirely to the right side of the midsagittal plane in patients with neglect. This spatial distribution of exploratory eye movements changed remarkably with left-sided neck muscle vibration as well as with left-sided vestibular stimulation using ice water calorics. The spatial area of exploration was significantly enlarged to the contralesional side and the exploration maximum shifted in the same direction. Whereas with both types of stimulation space exploration of patients with neglect was similar to that of normal subjects when not being stimulated, neck proprioceptive and vestibular stimulation in normal subjects induced a quasi neglect-like exploration pattern, i.e. a bias to one side of the objective midsagittal plane. If ocular space exploration was, however, related to the subjectively perceived position of the midsagittal plane in space, eye movements were symmetrically distributed and carried out to both sides of subjective straight ahead in all experimental conditions, in normal subjects as well as in patients with neglect. The present results support the above hypothesis and indicate that neck proprioceptive as well as vestibular input directly contribute to the computation of the subject's central representation of egocentric space used for localizing body orientation and for guiding motor behaviour in space.     

Epidemien und Pandemien in der hausärztlichen Praxis

Background

As primary care givers with a coordinating function, general practitioners (GP) play a key role in dealing with epidemics and pandemics. As of yet, there are no studies in Germany describing the difficulties experienced by GPs in patient care during epidemics/pandemics.

Objectives

This study aimed at identifying the problem areas in GPs’ patient care during the H1N1 and EHEC (enterohemorrhagic strain of Escherichia coli) outbreaks. With this information, recommendations for guaranteeing proper patient care during future epidemics/pandemics can be derived.

Materials and methods

In all, 12 qualitative, semi-structured, open guideline interviews with GPs in Hamburg and Lübeck were conducted, transcribed, and evaluated with qualitative content analysis.

Results

Five areas in ambulatory patient care were identified in which changes are needed from the primary care perspective: provision of information for GPs, workload, financing of epidemic-related measures, organization of the practices, care of those taken ill.

Conclusions

The workload of GPs in particular can and should be reduced through successful, centralized information distribution during epidemics/pandemics. The GP’s function as a coordinator should be supported and consolidated, in order to relieve the in-patient sector in cases of an epidemic/pandemic. Secured financing of epidemic-associated measures can help ensure patient care.     

Angiotensin II type 1 receptor expression in human coronary arteries with variable degrees of atherosclerosis

Autopsy specimens of human coronary arteries were collected from 65 men and women ranging in age from 40–76 years of age. We made 209 coronary artery sections, which were graded in terms of severity of atherosclerosis by means of the Stary classification. Sections were stained using an antibody directed against the angiotensin II type 1 (AT1) receptor. We found that in non-atherosclerotic sections, staining was confined to vascular smooth muscle cells in the media. However, with the advent of atherosclerosis, AT1 receptor expression was also present in atherosclerotic plaque and involved other cell types including inflammatory cells and myofibroblasts. We identified a remarkable correlation between AT1 receptor staining and the severity of coronary atherosclerosis as well as intima-media thickness. These human data correspond well to animal models of atherosclerosis indicating an upregulation of AT1 receptor expression in atherosclerotic tissue. Received: 7 June 2001/Returned for 1. revision: 28 June 2001/1. Revision received: 31 July 2001/Returned for 2. revision: 20 August 2001/2. Revision received: 11 March 2002/Accepted: 11 March 2002