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Biomedical subjects

R Kunz

Publications and source records attributed to R Kunz.

At least 19 recordsLinked to original sources
PubMed2002

Do short courses in evidence based medicine improve knowledge and skills? Validation of Berlin questionnaire and before and after study of courses in evidence based medicine.

OBJECTIVE: To develop and validate an instrument for measuring knowledge and skills in evidence based medicine and to investigate whether short courses in evidence based medicine lead to a meaningful increase in knowledge and skills. DESIGN: Development and validation of an assessment instrument and before and after study. SETTING: Various postgraduate short courses in evidence based medicine in Germany. PARTICIPANTS: The instrument was validated with experts in evidence based medicine, postgraduate doctors, and medical students. The effect of courses was assessed by postgraduate doctors from medical and surgical backgrounds. INTERVENTION: Intensive 3 day courses in evidence based medicine delivered through tutor facilitated small groups. MAIN OUTCOME MEASURE: Increase in knowledge and skills. RESULTS: The questionnaire distinguished reliably between groups with different expertise in evidence based medicine. Experts attained a threefold higher average score than students. Postgraduates who had not attended a course performed better than students but significantly worse than experts. Knowledge and skills in evidence based medicine increased after the course by 57% (mean score before course 6.3 (SD 2.9) v 9.9 (SD 2.8), P<0.001). No difference was found among experts or students in absence of an intervention. CONCLUSIONS: The instrument reliably assessed knowledge and skills in evidence based medicine. An intensive 3 day course in evidence based medicine led to a significant increase in knowledge and skills.

Clinical Competence↗
PubMed2001

(22)Ne(alpha,n)(25)Mg: the key neutron source in massive stars.

The excitation function of the reaction (22)Ne(alpha,n)(25)Mg, the key neutron source in the astrophysical s process in massive stars, has been determined from threshold at E(alpha) = 570 up to 1450 keV with an experimental sensitivity of 10(-11) b. For all resonances in this energy range new resonance parameters have been measured. For a possible resonance at about 635 keV a new upper limit omega gamma < 60 neV for the strength was obtained. Based on the new data, improved reaction rates were calculated as a function of temperature. The new uncertainty limits are considerably smaller than in previous determinations, ruling out the large enhancement factors, up to 500, assumed in some stellar model calculations.

Journal Article↗
PubMed2001

12C(alpha,gamma)16O: the key reaction in stellar nucleosynthesis.

The angular distributions of gamma rays from the 12C(alpha,gamma)16O reaction have been measured at 20 energy points in the energy range E(cm) = 0.95 to 2.8 MeV. The sensitivity of the present experiment compared to previous direct investigations was raised by 1-2 orders of magnitude, by using an array of highly efficient ( 100%) Ge detectors shielded actively with BGOs, as well as high beam currents of up to 500 microA that were provided by the Stuttgart Dynamitron accelerator. The S(E1) and S(E2) factors deduced from the gamma angular distributions have been extrapolated to the range of helium burning temperatures applying the R-matrix method, which yielded S(300)(E1) = (76+/-20) keV b and S(300)(E2) = (85+/-30) keV b.

Journal Article↗
PubMed2001

[Severely injured patients after the initial phase--vegetative state or remaining cognitive functions?].

BACKGROUND: We wanted to quantify improvements in the subacute rehabilitation phase in patients with severe brain injuries classified as vegetative or minimal brain consciousness. MATERIAL AND METHODS: Five patients were studied during a 12 months period using a method called Coma Recovery Scale (CRS) as described by Giacino et al. (1991). The parameters measured included visual and hearing functions, motor functioning, oromotor/verbal function, communication, and arousal. The observations of the patients and commandos given were standardised in a manual, and the responses achieved from the patients were recorded according to a scale for each parameter. RESULTS: This procedure for measuring closely the progress over time in these severely brain injured patients, was used for planning a realistic rehabilitation program. It was found to be very practical in communication with relatives of the patients and with the other therapists involved. INTERPRETATION: By decomposing the cognitive functions by this method using all the available possibilities for inputs, even minimal improvement in the cognitive functions mentioned could be uncovered and recorded.

Adolescent↗
PubMed2001

Studies of symptoms in primary care.

Publications on the frequency of defined symptoms in the practice setting, underlying conditions and prognosis have been rare in the past. Also, studies addressing these questions have suffered from several methodological problems. We therefore developed criteria to help investigators improve the quality of study design, implementation and publication. Studies evaluating symptoms in practice can make an important contribution to a more rational approach to diagnostic decision making especially in primary care.

Diagnosis↗
PubMed2001

[Development of quality assurance criteria for continuing education in evidence-based medicine].

OBJECTIVE: To develop a set of core contents for teaching evidence-based medicine (EBM). METHOD: Description of basic principles from clinical epidemiology, medical statistics and literature search essential for health care practitioners to perform critical appraisal of the medical literature. Based on textbooks for EBM and clinical epidemiology and guided by the EBM courses at McMaster university and the Oxford Centre for EBM, core contents were defined. Decision on inclusion was made by consensus. RESULTS: The core contents for the Berlin curriculum in EBM covers 3 areas: 1. General information on the methods of experimental and observational clinical studies, principles of EMB, basic statistical concepts, and literature search. 2. Tools for critical appraisal of primary studies required for medical decision making: therapy, diagnosis, prognosis, and harm. 3. Evidence-based summary reports: meta-analysis and guidelines. CONCLUSIONS: The contents of EBM can be precisely defined. They are transparent, explicit and communicable and present a reproducible basis for the different forms of teaching EBM.

Education, Medical, Continuing↗
PubMed2000

Practice variations in the evaluation of adult candidates for cadaveric kidney transplantation: a survey of the European Transplant Centers.

BACKGROUND: This survey was conducted to investigate similarities and differences in the diagnostic evaluation of adult candidates for cadaveric renal transplantation and the criteria for acceptance to the cadaveric renal transplant waiting-list in the European transplant centers. METHODS: A questionnaire listing 45 diagnostic procedures (consultations of 9 specialties, 18 imaging techniques and 18 laboratory investigations), 45 medical conditions constituting possible reasons for exclusion from renal transplantation, and 10 properties characterizing the responding transplant center was sent to 214 European transplant centers. RESULTS: A completed questionnaire was returned by 154 of 214 centers (72%). Significant disagreement (P<0.001) exists about the necessity of 28 of the 45 surveyed diagnostic procedures and about the acceptability of transplant candidates for 15 of the 45 surveyed medical conditions. The influence of center characteristics on the observed practice variations was examined by multinomial logistic regression (factors: Center size, waiting-list pressure, responsibility for organizing the diagnostic work-up, status of transplant center, responsibility for decision about acceptance of candidates and geographic location of center): In 13 of 28 controversial diagnostic procedures, geographic location of the centers turned out to be the only significant determining factor (P<0.001), whereas the dissent about medical conditions is not influenced significantly by the analyzed factors. CONCLUSION: The detected significant practice variations in the evaluation of renal transplant candidates may either indicate where scientific evidence is missing and more clinical research is needed or where the existing evidence has not been adequately disseminated and convincing guidelines should be established.

Adult↗
PubMed2000

Cationic ruthenium allenylidene complexes as catalysts for ring closing olefin metathesis

A series of well accessible cationic ruthenium allenylidene complexes of the general type [(eta6-arene)(R3P)RuCl(=C=CR'2)]+ X- is described which constitute a new class of pre-catalysts for ring closing olefin metathesis reactions (RCM) and provide an unprecedented example for the involvement of metal allenylidenes in catalysis. They effect the cyclization of various functionalized dienes and enynes with good to excellent yields and show a great tolerance towards an array of functional groups. Systematic variations of their basic structural motif have provided insights into the essential parameters responsible for catalytic activity which can be enhanced further by addition of Lewis or Bronsted acids, by irradiation with UV light, or by the adequate choice of the "non-coordinating" counterion X-. The latter turned out to play a particularly important role in determining the rate and selectivity of the reaction. A similarly pronounced influence is exerted by remote substituents on the allenylidene residue which indicates that this ligand (or a ligand derived thereof) may remain attached to the metal throughout the catalytic process. X-ray crystal structures of the catalytically active allenylidene complexes 3b.PF6 and 15.OTf as well as of the chelate complex 10 required for the preparation of the latter catalyst are reported.

Journal Article↗
PubMed2000

Influence of cold ischemia time, pretransplant anti-porcine antibodies, and donor/recipient size matching on hyperacute graft rejection after discordant porcine to cynomolgus kidney transplantation.

Organs transplanted between phylogenetically disparate species, such as from the pig into the primate, are subject to hyperacute rejection (HAR). This form of xenograft rejection is mediated by preformed natural antibodies and is believed to occur invariably in discordant xenografts thus leading to rapid destruction and complete thrombosis of the graft. Recent data, however, have shown that in the porcine to cynomolgus monkey setting, HAR is not inevitably seen after porcine kidney transplantation. The influence of preoperative antiporcine antibody levels in the recipient, cold ischemia time, and donor organ weight on the onset of HAR was investigated by using unmodified large white pigs (aged 3-12 weeks) as organ donors and adult cynomolgus monkeys (aged 1.5-3.5 years) as recipients. Porcine kidney xenotransplantation was performed in either a non-life-supporting model (n=7) or in a life-supporting model (n=8). In both models, no correlation was found between cold ischemia time and HAR. When preoperative anti-porcine antibody levels were investigated, a significant increase in incidence of HAR was observed in animals with elevated anti-porcine IgM (P<0.05) but not IgG levels (P=NS). Interestingly, although 5 of 12 grafts with an organ weight of less than 50 g underwent HAR, none of three grafts with a donor organ weight of more than 70 g showed signs of HAR. In addition, all three larger grafts showed intraoperative and postoperative urine production, although only in 1 (48 g) of the 12 grafts weighing less than 50 g primary graft function was observed. In one animal, a second porcine kidney (23 g) was successfully transplanted (without HAR) immediately after HAR and subsequent removal of a first porcine kidney (20 g). These results indicate that in the porcine to cynomolgus monkey setting anti-porcine IgM rather than IgG anti-porcine antibody levels seem to be of predominant importance for the induction of HAR. By increasing the donor organ size and weight the frequency of the onset of HAR can be at least reduced. This is most likely due to immunoabsorption of the recipients preformed antibodies in the porcine kidney without lethal damage for the graft.

Acute Disease↗
PubMed2000

[Evidence-based medicine--from evidence production to its implementation].

Evidence-based medicine (EBM) and evidence-based health care (EBHC) is one answer to the increasing need for quality and transparency in the care of individual patients as well as health care services. Using explicit and sound methodological criteria, EBM and EBHC question current management strategies for their effectiveness and usefulness to individual patients and patient groups. This approach therefore supports the implementation of rational patient-oriented care.

Clinical Trials as Topic↗
PubMed2000

[Goals and methods of clinical studies].

The validity of clinical patient-oriented research is always threatened by the influence of bias, confounding factors or random effects that might distort the results. However, the susceptibility to distortion varies between different study designs. The best protection against spurious relationships or distorted results are specific focused research questions and rigorous integration of sound study methodology during the design and performance phase.

Alcohol Drinking↗
PubMed2000

Effect of ethanol on dynamic visual acuity during vertical body oscillation in healthy volunteers.

Visual orientation is the most important sensory input during locomotion (e.g. walking, driving a car, riding a bicycle). We investigated dynamic visual acuity (DVA) during vertical body-oscillations (amplitude 5 cm; frequency 1.5 Hz) in 12 healthy subjects before and twice after ethanol consumption. During oscillation, vertical eye movements were recorded under two test conditions: with eyes closed (EC) and during DVA testing. A significant increase in vertical eye-amplitude after ethanol ingestion occurred only during EC tests, as a possible sign of vestibular hyperreaction. During vestibular stimulation alone (EC), ethanol did not affect the phase shift between stimulus and eye movements. However, when the subjects were given an additional visual stimulus (DVA), the post-alcohol phase shift rose significantly. Surprisingly, the post-alcohol phase shift values for the two test conditions showed no significant differences. After ethanol ingestion we found no changes in static visual acuity but a significant loss of DVA. Volunteers with a change of DVA threshold (DVAT) showed significantly (P = 0.004) higher post-alcoholic changes in the phase shift. In summary, low doses of ethanol disturbed the visually guided oculomotor response during fixation of an earth-fixed target while the observer was subject to linear vertical acceleration. This effect led to an increasing delay between the beginning of body and eye movements. The consequence was an increasing phase shift and thus a decrease in DVA during whole-body oscillation which was comparable to movements during human locomotion.

Acceleration↗
PubMed2000

The localization of an imaginary target under the influence of caloric vestibular stimulation in healthy adults.

It is well known that fixation of an imaginary target (IT) can influence the vestibulo-ocular reflex, but reports on the effect of peripheral vestibular stimulation on the localization of an IT are still lacking. In a prospective study, errors in pointing towards an IT without and after cold caloric vestibular stimulation (VS) were investigated in 24 right-handed volunteers with the head tilted backwards by 60 degrees. After the stationary target had been extinguished for 120 s each subject had to point towards the target position as remembered in darkness. The vestibular response was recorded by electronystagmography. Without VS 73% of the volunteers showed a systematic horizontal pointing error towards the right side. VS led to an increased horizontal pointing error in the direction of the slow phase of the induced nystagmus and the degree of deviation showed a significant (P = 0.001) positive correlation (r = 0.32) with the amplitude of the calorically induced nystagmus. In summary, an IT is not merely a useful visual stimulus for influencing the vestibulo-ocular reflex during linear and angular acceleration. A peripheral vestibular stimulation is itself able to change the position of an IT significantly and the extent of deviation shows a significant correlation with the amplitude of the evoked nystagmus.

Adult↗
PubMed2000

Dynamic visual acuity during linear acceleration along the inter-aural axis.

We investigated visual-vestibular interactions during linear acceleration along the inter-aural axis. Eighteen healthy volunteers and two patients with central neurological diseases were subjected to transaural linear acceleration in the direction of gravity force (frequency: 0.5-1.5 Hz; amplitude: 5 cm). During linear acceleration, eye movements were recorded under three test conditions: eyes closed (EC), while staring at an imaginary target (IT) and during the testing of dynamic visual acuity (DVA). As parameters of evaluation we used the amplitude of horizontal eye movements, phase shift and the decrease of DVA threshold (DVAT). Under all test conditions, eye amplitude increased with rising stimulus frequency and exceeded, especially in the higher frequency range, a hypothetically calculated eye amplitude for smooth pursuit. The combination of a visual and vestibular input (DVA and IT) led to a better compensation (lower phase shift) than under vestibular stimulation alone (EC). Eye movements during low-frequency stimulation depended more on the visual system while responses in the higher frequency range were mainly triggered by the otolith organ. At 1.5 Hz the compensatory function of the visual-vestibular system was limited (rising phase shift) and DVAT decreased even in a significant number of healthy subjects. Patients with diseases of the central nervous system showed a higher phase shift and thus a stronger decrease of DVAT (two levels) already at a stimulus frequency of 1.25 Hz.

Acceleration↗