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Biomedical subjects

R Ernst

Publications and source records attributed to R Ernst.

At least 19 recordsLinked to original sources
PubMed2003

Familial leiomyomatosis: a review and discussion of pathogenesis.

Multiple cutaneous leiomyomas of pilar origin have long been recognized to have an autosomal dominant inheritance. While the skin tumors are relatively uncommon and benign, women of affected families often develop uterine fibroids with associated infertility, pain and bleeding. In addition, a subset of these families harbors a predisposition to papillary renal cell carcinoma. Germline mutations in a recently identified classical tumor suppressor gene encoding fumarate hydratase are observed in these individuals. Appropriate screening measures for associated disorders are mandatory.

Female↗
PubMed2001

Combining speech recognition software with Digital Imaging and Communications in Medicine (DICOM) workstation software on a Microsoft Windows platform.

This presentation describes our experience in combining speech recognition software, clinical review software, and other software products on a single computer. Different processor speeds, random access memory (RAM), and computer costs were evaluated. We found that combining continuous speech recognition software with Digital Imaging and Communications in Medicine (DICOM) workstation software on the same platform is feasible and can lead to substantial savings of hardware cost. This combination optimizes use of limited workspace and can improve radiology workflow.

Humans↗
PubMed2001

Wind-induced ventilation of the giant nests of the leaf-cutting ant Atta vollenweideri.

To understand the significance of elaborate nest architecture for the control of nest climate, we investigated the mechanisms governing nest ventilation in a large field nest of Atta vollenweideri. Surface wind, drawing air from the central tunnels of the nest mound, was observed to be the main driving force for nest ventilation during summer. This mechanism of wind-induced ventilation has so far not been described for social insect colonies. Thermal convection, another possible force driving ventilation, contributed very little. According to their predominant airflow direction, two functionally distinct tunnel groups were identified: outflow tunnels in the upper, central region, and inflow tunnels in the lower, peripheral region of the nest mound. The function of the tunnels was independent of wind direction. Outflow of air through the central tunnels was followed by a delayed inflow through the peripheral tunnels. Leaf-cutting ants design the tunnel openings on the top of the nest with turrets which may reinforce wind-induced nest ventilation.

Animals↗
PubMed2001

The power law distribution for walking-time intervals correlates with the ellipsoid-body in Drosophila.

The temporal properties of a variety of behavioral traits obey power law distributions, a property often referred to as fractal. We recently showed that the temporal pattern of locomotor activity of the fruitfly Drosophila melanogaster follows this distribution. Although an increasing number of such fractal patterns are being discovered, the brain areas and neuronal networks responsible remain unknown. In this study, we show that specifically blocking synapses established by neurons of the Drosophila ellipsoid-body, a substructure of the central complex in the brain, leads to a loss of the fractal properties in the temporal pattern. We conclude that the temporal fractal pattern of locomotor activity is regulated in the ellipsoid-body.

Animals↗
PubMed2000

Stringent tests of shell model calculations in fp shell nuclei (46, 48)Ti and (50,52)Cr from measurements of g factors and B(E2) values

Measurements of magnetic moments and lifetimes of 2(+)(1) and 4(+)(1) states of (46,48)Ti and (50,52)Cr were performed with high accuracy via projectile Coulomb excitation and the technique of transient magnetic fields. The high quality of the data allows for the first time to establish stringent constraints on large scale shell model calculations. Whereas the global behavior of the data is well explained by full fp shell model calculations, distinct deviations in the g factors and B(E2) values of (46,48)Ti from theoretical predictions can be attributed to excitations of the 40Ca core. This suggestion is supported by recent Monte Carlo calculations which provide evidence that 48Ca is a better inert core.

Journal Article↗
PubMed2000

[An instrument for evaluating the psychiatric personnel regulation].

Since 1991, the Psychiatrie-Personalverordnung (Psych-PV) regulates the allocation of personnel in German psychiatric hospitals and psychiatric wards. Psych-PV defines the personnel's diagnostic and therapeutic tasks based on an illness severity scale. A group of experts from the Medical Advisory Services of Social Security--Health Insurance (MDK) has developed a questionnaire as an instrument to systematically gather, from a given hospital, structural data relevant for application of Psych-PV. The questionnaire consists of two parts, relating to the hospital and to the individual wards. The hospital supplies information such as statutory catchment area, types of care offered, capacity, personnel, organisational structure, patients' diagnoses, and co-operation with complementary institutions. The section pertaining to individual wards collects data on admission and discharge, duration of treatment, re-admissions, and internal transfer. The distribution of the severity of patients' illnesses within individual wards, which has been defined in the budget, is the basis for a review of the actual number of staff as well as of the realization of basic tasks of diagnostics and treatment. Questions pertaining to treatment concepts in individual wards are aimed to ascertain the degree of agreement with the conceptual goals of Psych-PV. The methods of treatment offered in a given ward can be gleaned from its weekly organisation-plan. Indications for the realization of basic tasks of diagnostics and treatment can be derived from the information supplied by each personnel group of a ward with regard to specific tasks of individual and group treatment. The questionnaire developed by the MDK in Hessen allows to review the extent to which the allocation of staff according to Psych-PV on the level of the individual ward translates into appropriate treatment options. The questionnaire also offers a basis for a comparison of hospitals.

Evaluation Studies as Topic↗
PubMed2000

Defective pigment granule biogenesis and aberrant behavior caused by mutations in the Drosophila AP-3beta adaptin gene ruby.

Lysosomal protein trafficking is a fundamental process conserved from yeast to humans. This conservation extends to lysosome-like organelles such as mammalian melanosomes and insect eye pigment granules. Recently, eye and coat color mutations in mouse (mocha and pearl) and Drosophila (garnet and carmine) were shown to affect subunits of the heterotetrameric adaptor protein complex AP-3 involved in vesicle trafficking. Here we demonstrate that the Drosophila eye color mutant ruby is defective in the AP-3beta subunit gene. ruby expression was found in retinal pigment and photoreceptor cells and in the developing central nervous system. ruby mutations lead to a decreased number and altered size of pigment granules in various cell types in and adjacent to the retina. Humans with lesions in the related AP-3betaA gene suffer from Hermansky-Pudlak syndrome, which is caused by defects in a number of lysosome-related organelles. Hermansky-Pudlak patients have a reduced skin pigmentation and suffer from internal bleeding, pulmonary fibrosis, and visual system malfunction. The Drosophila AP-3beta adaptin also appears to be involved in processes other than eye pigment granule biogenesis because all ruby allele combinations tested exhibited defective behavior in a visual fixation paradigm.

Adaptor Protein Complex alpha Subunits↗
PubMed2000

Combined intravenous and intra-arterial recombinant tissue plasminogen activator in acute ischemic stroke.

BACKGROUND AND PURPOSE: A retrospective analysis was performed on 20 consecutive patients who presented with severe acute ischemic stroke and were evaluated for a combined intravenous (IV) and local intra-arterial (IA) recombinant tissue plasminogen activator (rtPA) thrombolytic approach within 3 hours of onset. METHODS: Twenty consecutive patients with carotid artery distribution strokes were evaluated and treated using a combined IV and IA rtPA approach over a 14-month period (September 1998 to October 1999). rtPA (0.6 mg/kg) was given intravenously (maximum dose 60 mg); 15% of the IV dose was given as bolus, followed by a continuous infusion over 30 minutes. A maximal IA dose, up to 0.3 mg/kg or 24 mg, whichever was less, was given over a maximum of 2 hours. IV treatment was initiated within 3 hours in 19 of 20 patients. All 20 patients underwent angiography, and 16 of 20 patients received local IA rtPA. RESULTS: The median baseline National Institutes of Health Stroke Scale (NIHSS) score for the 20 patients was 21 (range 11 to 31). The median time from stroke onset to IV treatment was 2 hours and 2 minutes, and median time to initiation of IA treatment was 3 hours and 30 minutes. Ten patients (50%) recovered to a modified Rankin Scale (mRS) of 0 or 1; 3 patients (15%), to an mRS of 2; and 5 patients (25%), to an mRS of 4 or 5. One patient (5%) developed a symptomatic intracerebral hemorrhage and eventually died. One other patient (5%) expired because of complications from the stroke. CONCLUSIONS: We believe that the greater-than-expected proportion of favorable outcomes in these patients with severe ischemic stroke reflects the short time to initiation of both IV and IA thrombolysis.

Acute Disease↗
PubMed1999

Context generalization in Drosophila visual learning requires the mushroom bodies.

The world is permanently changing. Laboratory experiments on learning and memory normally minimize this feature of reality, keeping all conditions except the conditioned and unconditioned stimuli as constant as possible. In the real world, however, animals need to extract from the universe of sensory signals the actual predictors of salient events by separating them from non-predictive stimuli (context). In principle, this can be achieved if only those sensory inputs that resemble the reinforcer in their temporal structure are taken as predictors. Here we study visual learning in the fly Drosophila melanogaster, using a flight simulator, and show that memory retrieval is, indeed, partially context-independent. Moreover, we show that the mushroom bodies, which are required for olfactory but not visual or tactile learning, effectively support context generalization. In visual learning in Drosophila, it appears that a facilitating effect of context cues for memory retrieval is the default state, whereas making recall context-independent requires additional processing.

Animals↗
PubMed1999

Efficacy of disinfection of shell eggs externally contaminated with Salmonella enteritidis. Implications for egg testing.

Experimental contamination of the surface of shell eggs by dipping in a culture of Salmonella enteritidis resulted in the presence of Salmonella enteritidis in/on the shells as well as shell membranes but not in the egg content. Disinfection with Lugol's solution, chlorhexidine, ethanol, quarternary ammonium solutions or flaming after dipping in ethanol failed to achieve complete decontamination of the shell and membranes with resulting false positives when eggs were broken for culturing of the content. Dipping eggs for three seconds in boiling water resulted in complete destruction of Salmonella enteritidis in shells and membranes but sometimes caused the eggs to crack. A method of aseptically opening eggs without risk of contaminating the content from the shell or membrane was developed. Salmonella enteritidis deposited in/on the shell and membranes did not multiply during storage of the eggs at 20 degrees C for four weeks, the counts seemed to decrease. No Salmonella enteritidis was detected in the contents of any contaminated eggs.

Animals↗
PubMed1999

A picture archiving and communications system featuring multiple monitors using Windows98.

We present an effective approach to manage, review, and distribute Digital Imaging and Communications in Medicine (DICOM) images with multiple monitors using Windows98 (Microsoft Corp, Redmond, WA) that can be implemented in an office-based setting. Computed tomography (CT), magnetic resonance imaging (MRI), and angiographic DICOM images were collected, compressed, and stored using Medweb (Medweb, Inc, San Francisco, CA) software. The Medweb server used the Linux/UNIX operating system on a Pentium 333-MHz processor with 128 MB of RAM. Short-term storage capacity was about 2 weeks with routine usage of an 11-GB hard drive. Images were presented for reading on a dual-monitor Windows98 Pentium display station with 160 MB of RAM using a Medweb/Netscape (Netscape Communications Corp, Mountain View, CA) viewer. There was no significant discrepancy in diagnosis between electronic and conventional film images. Mean reading time for 32 cases was 118 seconds. The Medweb JAVA plug-in viewer loaded the first image within 30 seconds of selecting the case for review. Full uncompressed 16-bit images allowed different window settings to better assess for pathology. Multiple monitors allowed viewing various hanging protocols. Cine viewing was also possible. Key diagnostic images were electronically transmitted to referring physicians. On-call radiologists were able to access images through the Internet. By combining Medweb, DICOM, and web-browser software using desktop personal computers (PCs), an easily accessible picture archiving and communications system (PACS) is available to radiologists and referring physicians. Multiple monitors are easily configured and managed using Windows98. This system can sustain changes and can be extended to provide variable functions using inexpensive PCs.

Angiography↗
PubMed1999

Temporal pattern of locomotor activity in Drosophila melanogaster.

The temporal pattern of locomotor activity of single Drosophila melanogaster flies freely walking in small tubes is described. Locomotor activity monitored by a light gate has a characteristic time-course that depends upon age and the environmental conditions. Several methods are applied to assess the complexity of the temporal pattern. The pattern varies according to sex, genotype, age and environmental conditions (food; light). Activity occurs clustered in bouts. The intrinsic bout structure is quantified by four parameters: number of light gate passages (counts) per bout, duration of a bout, pause between two successive bouts and mean bout period. In addition, the distribution of the periods between light-gate crossings (inter-count intervals) as function of inter-count interval duration reveals a power law, suggesting that the overall distribution of episodes of activity and inactivity has a fractal structure. In the dark without food, the fractal dimension which represents a measure of the complexity of the pattern is sex, genotype and age specific. Fractality is abolished by additional sensory stimulation (food; light). We propose that time-course, bout structure and fractal dimension of the temporal pattern of locomotor activity describe different aspects of the fly's central pattern generator for locomotion and its motivational control.

Aging↗
PubMed1999

The memory template in Drosophila pattern vision at the flight simulator.

Pattern recognition is studied in flight orientation of fixed flying Drosophila melanogaster controlling the horizontal rotations of an arena. Earlier experiments had suggested a simple mechanism of pattern recognition in which a memory template and the actual image are retinotopically matched. In contrast, we now show that Drosophila extracts at least two and probably four pattern parameters: size, vertical position of the center of gravity and, presumably horizontal/vertical extent as well as vertical separatedness of pattern elements. Moreover, the fly treats isolated pattern elements as a compound figure. Retinal transfer is possible between training and test if the centers of gravity of the compound figures are retained.

Animals↗
PubMed1999

Multiple mechanisms are involved in the acute vasodilatory effect of 17beta-estradiol in the isolated perfused rat heart.

The purpose of this study was to define the dose-dependent effects of 17beta-estradiol on coronary flow and cardiac function in isolated rat hearts and to identify the mechanisms involved in its vasodilator action. Hearts from female and male Wistar rats were perfused at constant pressure (100 mm Hg). Stereoisomer specificity and the mechanism of vasodilation by 17beta-estradiol were examined in female rat hearts. Function was measured by a left ventricular (LV) balloon and coronary flow (CF) with an ultrasonic flowmeter. 17Beta-estradiol at 10(-6), 5 x 10(-6), and 10(-5) M increased CF in female hearts by 5 +/- 2, 27 +/- 4 (p < 0.05 vs. baseline), and 40 +/- 4% (p < 0.05 vs. baseline), respectively. The effect of 17beta-estradiol in hearts from male rats was similar but less pronounced compared with females [deltaCF 8 +/- 3, 19 +/- 3 (p < 0.05 vs. baseline)] and 25 +/- 7% (p < 0.05 vs. baseline; p < 0.05 vs. female 17beta-estradiol). Maximum vasodilation by the stereoisomer 17alpha-estradiol was significantly smaller [deltaCF 5 +/- 3, 4 +/- 3 (p < 0.05 vs. female 17beta-estradiol) and 14 +/- 1% (p < 0.05 vs. baseline; p < 0.05 vs. female 17beta-estradiol)] for 10(-6), 5 x 10(-6), and 10(-5) M. Pretreatment with the NO-synthesis inhibitor Nomega-methyl-L-arginine (10(-4) M) had no effect on the maximal vasodilator response to 17beta-estradiol (10(-5) M) [deltaCF 36 +/- 6% (p < 0.05 vs. baseline)]. When hearts were pretreated with the prostaglandin-synthesis inhibitor diclofenac (10(-6) M), the maximal vasodilator effect of 17beta-estradiol was partially attenuated [deltaCF 12 +/- 7% (p < 0.05 vs. female 17beta-estradiol)]. Similarly, pretreatment with the K+ATP-blocker glibenclamide (10(-6) M) partially inhibited the maximal vasodilator effect of 17beta-estradiol [deltaCF 22 +/- 6% (p < 0.05 vs. baseline; p < 0.05 vs. female 17beta-estradiol)]. Pretreatment with the Ca2+ channel antagonist nifedipine (7.2 x 10(-8) M) completely blocked the vasodilator effect. In isolated perfused rat hearts, 17beta-estradiol induced marked acute coronary vasodilation; this effect is in part gender specific, and in female hearts, largely stereoisomer specific. The dilator effect is mediated predominantly by calcium channel blockade, but prostaglandin release and K+ATP channel activation also are involved. In the isolated perfused rat heart, NO production does not contribute to the acute vasodilator effect of 17beta-estradiol.

Animals↗
PubMed1999

The virtual lecture: delivery of live and recorded presentations over the Internet.

OBJECTIVE: Our objective was to deliver live and recorded lectures, with images, over the Internet using streaming media. CONCLUSION: Streaming media are an emerging technology that can deliver live lectures over the Internet using standard PCs and modems. These lectures are also simultaneously recorded and can be played back at any time by individuals with access to the Web.

Education, Distance↗
PubMed1999

[Dimensions of work stress and job satisfaction in psychiatric-psychotherapeutic practice].

Empirical studies of nursing in psychiatry and psychosomatics rarely consider the dialectics between work load and positive aspects of social support. Resulting from theoretical considerations and practical experiences seven dimensions were defined that might influence overall job satisfactions and stress. To measure this, a questionnaire containing 53 items was developed. This instrument was answered by 134 nurses of a psychiatric hospital. The results show that factor analysis and item analysis only partly confirm the presumptions. The five empirical scales include "stress due to work conditions and patients", "collaboration in teamwork", "collaboration with physicians and therapists", "collaboration with superiors in nursing" and "responsibility, competence and decision-making". Theoretical dimensions and empirical scales are discussed. The high work stress caused by work conditions and difficult patients is compensated by a positive evaluation of the collaboration in the nursing-team with physicians and therapists as well as with superiors.

Adult↗