Biomedical subjects

A Roessler

Publications and source records attributed to A Roessler.

7 recordsLinked to original sources

PubMed2006

Renal adrenomedullin and high altitude diuresis.

Previous investigations revealed that most of the fluid regulating hormones showed no consistent relationship to the hypoxic diuretic response (HDR). In this study we examined if adrenomedullin (AM), a hypoxia-mediated diuretic/natriuretic peptide is connected to HDR. Thirty-three persons were examined at low altitude (LA), on the third exposure day at 3440 m (medium altitude, MA) and on the fourteenth day at 5050 m (high altitude, HA). Nocturnal diuresis rose from 460 ml [interquartile range 302 ml] at LA to 560 [660] ml at MA to 1015 [750] ml at HA (p<0.005). Sodium excretion was similar at LA and MA (41.8 [27.0] vs. 41.4 [28.4] mM) and increased to 80.2 [29.1] mM at HA (p<0.005). Urinary AM excretion was 7.9 [3.9] at LA, 7.5 [5.7] pM at MA, and increased to 10.5 [5.1] pM (p<0.05) at HA. Urinary AM excretion was correlated to diuresis (r=0.72, p<0.005) and sodium excretion (r=0.57, p<0.005). Plasma AM concentration rose from 16.4 [3.1] to 18.8 [4.9] pM/l at MA (p<0.005) and to 18.3 [4.3] pM/l at HA (p<0.005). Plasma AM concentration and urinary AM excretion were not correlated, neither were plasma AM concentration and diuresis or natriuresis. Our data suggest the involvement of increased renal AM production in the pathophysiology of high altitude fluid and sodium loss.

Adrenomedullin↗

PubMed2006

Aspirin resistance in secondary stroke prevention.

BACKGROUND: We investigated the platelet function in stroke patients treated with aspirin [acetylsalicylic acid (ASA)] for secondary stroke prevention during a follow-up period of 1 year. METHODS: In this prospective study 291 patients with first initiated aspirin therapy (300 mg/day) for secondary stroke prevention were included. Platelet aggregation measurements were performed 24 h, 3, 6, and 12 months after starting medication. RESULTS: Twenty-one of 291 patients (7.2%) were identified as primary ASA-non-responders (initial insufficient platelet inhibition) and 4.1% as secondary ASA-non-responders (insufficient platelet inhibition during follow-up). There were no significant differences between ASA-responders and ASA-non-responders concerning age, gender, risk factors, and stroke characteristics. CONCLUSION: Aspirin resistance in stroke patients is not uncommon. The clinical usefulness of routine platelet function tests needs to be proved by further trials.

Aged↗

PubMed2001

Immersive virtual environments in cue exposure.

Cue reactivity to drug-related stimuli is a frequently observed phenomenon in drug addiction. Cue reactivity refers to a classical conditioned response pattern that occurs when an addicted subject is exposed to drug-related stimuli. This response consists of physiological and cognitive reactions. Craving, a subjective desire to use the drug of choice, is believed to play an important role in the occurrence of relapse in the natural setting. Besides craving, other subjective cue-elicited reactions have been reported, including withdrawal symptoms, drug-agonistic effects, and mood swings. Physiological reactions that have been investigated include skin conductance, heart rate, salivation, and body temperature. Conditioned reactivity to cues is an important factor in addiction to alcohol, nicotine, opiates, and cocaine. Cue exposure treatment (CET) refers to a manualized, repeated exposure to drug-related cues, aimed at the reduction of cue reactivity by extinction. In CET, different stimuli are presented, for example, slides, video tapes, pictures, or paraphernalia in nonrealistic, experimental settings. Most often assessments consist in subjective ratings by craving scales. Our pilot study will show that immersive virtual reality (IVR) is as good or even better in eliciting subjective and physiological craving symptoms as classical devices.

Adult↗

PubMed1998

From toy to tool: the development of immersive virtual reality environments for psychotherapy of specific phobias.

Virtual Reality (VR) entered the mental health field some years ago. While the technology itself has been available for more than ten years now, there is still a certain amount of uncertainty among researchers and users as to whether VR will one day fulfill all it's promises. In this chapter we are giving an overview of the implementation of the technology in our mental health research facility in Basel, Switzerland. The development of two applications for use with claustrophobic and acrophobic patients perspectively serves just as an example within this context. Some may say, the chapter is too much based on technical considerations. Strictly speaking, VR is pure technology, even knowing that this special form of technology has sensory, psychological and even philosophical implications not known from other human computer interfaces so far. As far as we are concerned, the development of the technology for use within the mental health sector has merely just begun. As today's mostly used immersive output devices (Head-mounted Displays, shutter glasses) do not have a satisfactory resolution, do restrict movements and prevent multi-user-capabilities, there will be a soar of mental health applications the day some or at least the most important of these obstacles have been overcome.

Computer Simulation↗

PubMed1997

Diminished plasma cGMP during weightlessness.

We performed an experiment within the project "RLF" (Russian long-term flight) on a cosmonaut onboard the space station MIR. For creating an analogue to orthostatic stress, we used lower body negative pressure (LBNP) as stimulus. Decrease in central and peripheral baroreceptor load by LBNP can be used as a cardiovascular countermeasure in cosmonauts or for inducing endocrine responses. Altered steady-state plasma concentration values of volume sensitive hormones have been observed inflight as well as postflight. Within this project we measured plasma ANP and cGMP as second messenger. Changes in plasma cGMP concentration are generally considered to be a good indicator of those in ANP activity. However, in our experiments depression of cGMP during space flight was more impressive than ANP decline. We are not aware of previous measurements of plasma cGMP under these conditions, and believe to be the first to report complete suppression of plasma cGMP during long-term stay in space.

Atrial Natriuretic Factor↗

PubMed1989

A Novel Effect in Phycomyces Phototropism : Positive Bending and Compensation Spectrum in Far UV.

A novel effect-positive phototropic bending under far UV irradiation (between 260 and 305 nanometers) at low intensities-is reported. Natural compensation points (intensities which cause no bending under unilateral irradiation) have been determined for different wavelengths. The curve connecting these points, the compensation spectrum, divides the intensity-wavelength plane into areas of negative and positive tropism. It is further shown that a highly asymmetrical pattern of light stimulus within the sporangiophore underlies the symmetrical growth response at each compensation point. This suggests that some unknown additional factor is involved in perceiving a UV stimulus at the level of the photoreceptor. It is also demonstrated here that positive tropism in the UV range is due to a lens effect. We conclude that the hypothesis of optical attenuation of the stimulus (considered until now as the most plausible explanation of negative tropism in the UV spectral range) must be dismissed. The results presented here represent the first application of our quantitative theoretical consideration of spatial factors in phototropism heretofore neglected by others.

Journal Article↗

PubMedDate not supplied

Diversity among hospice volunteers: a challenge for the development of a responsive volunteer program.

Voluntary organizations such as hospices are increasingly being called upon to substitute for state health and social welfare delivery at a time when volunteer contributions are threatened because of organizational and demographic changes. These changes include: the adoption by the nonprofit sector of market strategies in response to health and social welfare reforms, increases in the size and complexity of hospices, increasing professionalization of staff, and the move of women away from voluntary work in the health and welfare services to paid employment. With these changes, hospices must be knowledgeable about their volunteer workforce and resourceful if they are to continue to attract and retain volunteers. A survey of volunteers conducted at the Mary Potter Hospice, Wellington, New Zealand, examined differences in volunteers' characteristics, motivations for joining hospice, and factors affecting work satisfaction according to age, gender, and the length of time volunteers had worked. Those findings of particular relevance to program development were: (1) the tendency for the recently recruited volunteers to be in paid employment; (2) the mixed motivations of the younger volunteers, reflecting both altruistic and personal gain needs; and (3) the rewards commonly identified by volunteers, such as feeling their work is of value, being accepted by hospice staff, and feeling like important team members. Practical outcomes of the study are described.

Adult↗