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Biomedical subjects

M Köhler

Publications and source records attributed to M Köhler.

At least 289 records · Page 16Linked to original sources
PubMedDate not supplied

Underground measurements of radioactivity.

The exceptional sensitivity of gamma-ray spectrometry in underground laboratories has increasing application because of the important science and technology that it allows to be studied. Early work focused on rare fundamental phenomena, e.g. double beta decay, but a growing number of underground measurements is being performed in fields such as environmental monitoring, surveillance of nuclear activities, benchmarking of other physical techniques and materials selection for equipment which require materials with extremely low levels of radioactivity. This report describes the state of the art in underground gamma-ray spectrometry. Backgrounds of HPGe-detectors at various underground laboratories are presented and compared. Improved techniques and detectors are described and needs of deep underground facilities for higher sensitivity measurements are discussed.

Journal Article↗
PubMedDate not supplied

Reference measurements of low levels of 60Co in steel.

Analysis of 60Co traces in the matrix steel has recently gained in importance. This paper deals with the low-level gamma-ray spectrometry measurements that were part of a recent German survey aiming at determining the present levels of artificial radionuclides in commercial steel. Specific 60Co activities in the order of 10(-5) Bq g(-1) were measured. To show equivalence in these measurements, a comparison exercise of European underground laboratories has been carried out, additionally.

Journal Article↗
PubMedDate not supplied

A complex chromosome rearrangement involving chromosome 8, 11, and 12 analyzed by conventional cytogenetic investigations, fluorescence in situ hybridisation, and spectral karyotyping.

We report on a 29-year-old woman with a history of five spontaneous abortions and a balanced complex chromosome rearrangement (CCR) involving break points between chromosomes 8, 11, and 12. Fluorescence in situ hybridisation (FISH) in combination with giemsa trypsin banding techniques were essential for the identification of the breakpoints. In addition, the results were confirmed by 24-colour FISH using the spectral karyotyping system (SKY). The karyotype was 46,XX,t(8;11;12)(8qter-->8p10::12p10-->12pter;11pter--> 11q14::8p10-->8pter;12qter-->12p10::11q14-->11qter). Application of SKY facilitated detection of all three chromosomes involved and supported the localisation of the breakpoints by a single time and sample saving investigation.

Abortion, Spontaneous↗
PubMedDate not supplied

Investigation of the soil-plant transfer of primordial radionuclides in tomatoes by low-level gamma-ray spectrometry.

The paper presents actual data from investigations of the soil-plant transfer of the primordial radionuclides 40K, 238U, 226Ra, 210Pb and 227Ac for tomatoes growing at soils from former uranium mining areas. The analysis were carried out using low-level gamma-ray spectrometry in a 47 m deep underground laboratory. For tomato fruits transfer factors of (0.0007 +/- 0.0006) for 235U, (0.0021 +/- 0.0017) for 226Ra, (0.0015 +/- 0.0009) for 210Pb and (0.0018 +/- 0.0012) for 227Ac were obtained. The investigation of the soil-plant transfer by low-level gamma-ray spectrometry is often limited by the Compton-continuum from the always present high-energy gamma-ray emitter 40K.

Actinium↗
PubMedDate not supplied

Comparison of methods for the analysis of 226Ra in water samples.

226Ra is one of the key nuclides among the natural radionuclides from the point of view of radiation protection. For monitoring the radiation exposure risk along the water pathway it has to be measured routinely with low detection limits. Because of the properties of 226Ra and its progenies, a number of quite different methods are possible for this purpose. This paper presents a comparison of routine techniques for the determination of 226Ra in water samples as applied by the authors.

Humans↗
PubMedDate not supplied

[Evaluation of a simple test for shoulder function in patients with surgically treated rotator cuff injuries].

INTRODUCTION: To assess overall shoulder function a simple examination of the range of motion and strength may not be sufficiently representative. because the shoulder in its daily use is often required for repetitive activities, fatigue at an early stage could be a sign of disturbed shoulder function. Therefore the shoulder function test (SFT) was created to incorporate the factor time into shoulder assessment. With this study the SFT was evaluated for its clinical use in the prospective follow-up of a series of patients operated on for rotator cuff tears. METHODS: Using forward flexion, the patient had to lift a 500-g weight onto a shelf placed at a height which he could reach with his extended arm. The achieved height (5 levels possible) and the time he needed for 5 repetitions were recorded. The SFT value was calculated by division of the time required by the level of the reached shelf. Thus, a lower SFT score represents a better shoulder function. This was tested on 45 patients prior to rotator cuff repair and at 3, 6 and 12 months postoperatively. As validation the SF-36 and the Constant score were evaluated in parallel. Construct, criterion, content and discriminative validity and responsiveness were calculated Results: At all assessments the SFT correlated with the Constant score (r = - 0.47 to r = - 0.62) and the SF-36 (r = - 0.26 to r = - 0.61) demonstrating construct validity. As criterion validity the SFT correlated with the reported pain (r = 0.34 to r = 0.61), patients' self-estimation (r = 0.38 to r = 0.59) and doctors' estimation of the patients shoulder function (r = 0.36 to r = 0.54). Known groups validity was positive as the SFT could differentiate between shoulders with and without rotator cuff tears. The SFT demonstrated a good responsiveness with significant improvement (p = 0.01) after rotator cuff repair. CONCLUSION: Repetitive forward flexion is an important function of the shoulder in daily activities. The SFT allows a reliable and valid quantitative measurement of this function. In order to improve functional assessment of the shoulder and scoring we would recommend using this patient- and function-orientated test in combination with the Constant score to document the current status of shoulder function.

Activities of Daily Living↗
PubMedDate not supplied

[Value of the new anticonvulsants in pediatrics].

Within the last years five new antiepileptics have become available in Germany. Vigabatrin is a second choice drug against partial seizures, West syndrome and epilepsies in infant encephalopathy syndromes. Lamotrigine and Gabapentin can be used as add-on therapy in partial seizures in children above 12 years of age Felbamate has a high incidence of severe side-effects like aplastic anemia and liver failure. Therefore it should be restricted to the treatment of Lennox-Gastaut syndrome. Oxcarbazepine is not yet on the German market, but is available by import from Austria. Its therapeutic range is similar to carbamazepine with less side-effects. The new antiepileptics discussed have turned out to be useful additional therapeutics, especially in focal epilepsies. There is, however, still limited experience with these drugs in children. So none can as yet be considered a drug of first choice in any epileptic childhood disorder. The classical antiepileptic drugs remain essential in antiepileptic therapy.

Adolescent↗
PubMedDate not supplied

[Neurologic complications in implantation of knee endoprostheses. A clinical and EMG-documented study].

In a retrospectively studied group of 253 knee joints treated by total replacement, six (2.4%) nerve lesions were clinically diagnosed. In the vast majority there was damage to the peroneal nerve, and in a single case also to the tibial nerve. After between one and three years only two patients still had permanently impaired function. In a second prospective study of 27 patients, examined by EMG before and after surgery, signs of bland, fresh neural damage was found in just under 30% following implantation of a knee joint prosthesis. In none of the cases had clinically manifest defunctionalization symptoms occurred. In the subsequent course, proof of far-reaching remission of the subclinical lesions was obtained, also by EMG. The causes of the perioperatively inflicted nerve lesions are discussed; the correction of axial defects (knee-bending contracture, genu valgum) in particular seems a likely cause of neural damage.

Electromyography↗
PubMedDate not supplied

Nuclear protein transport pathways.

Nuclear proteins like transcription factors and ribosomal proteins are synthesized in the cytoplasm and have to be transported into the nucleus to fulfill their functions. The transport of proteins >20-60 kD through the nuclear pore complex (NPC) into the nucleus is an active, energy-requiring process. Transport substrates are recognized by their transport proteins via certain signals. The best-characterized protein import pathway is the 'classical' nuclear localization signal-dependent pathway with importin alpha and beta carrying the substrate to the NPC. The transport of the importin-substrate complex into the nucleus is regulated by the small GTPase Ran/TC4. During the last years more than ten proteins have been discovered which have already been proven or are very likely to be nuclear transport factors of distinct import pathways: members of the importin alpha protein family are very similar and transport in complex with importin beta nuclear localization signal-bearing proteins into the nucleus. Members of the Ran-binding protein family show some weak similarity to importin beta. Sharing a common domain at the amino terminus, they are able to bind RanGTP, a prerequisite for their function as nuclear import or export factors for distinct proteins or RNAs. However, Ran/TC4 seems to play a key regulatory role in all nuclear transport pathways described so far, although the molecular mechanism of the translocation step through the NPC is still unclear.

Animals↗
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Multi-centre double-blind comparison of terfenadine once daily versus twice daily in patients with hay fever.

This double-blind, randomized multi-centre study was designed to compare efficacy and tolerability of 120 mg terfenadine taken once daily (in the morning) with the established regimen of 60 mg terfenadine taken twice daily in the treatment of seasonal rhinitis. Two comparable groups, a total of 191 hay fever patients, were treated for 1 week. Symptom severity was assessed by the investigators before and at the end of the treatment (visual analogue scale), and daily by the patient (four-point rating scale). All symptoms improved to a similar degree in both groups. Differences between the two groups were not statistically significant, except for nasal symptoms in three cases as assessed by the visual analogue scale in one centre (better relief in the group given 120 mg terfenadine once daily). Tolerability was good and similar in both groups. The data presented show that in the treatment of hay fever 120 mg terfenadine given once daily is an effective, convenient and well tolerated alternative to the regimen of 60 mg terfenadine given twice daily.

Adult↗
PubMedDate not supplied

Implantation of stimulation electrodes in the subretinal space to demonstrate cortical responses in Yucatan minipig in the course of visual prosthesis development.

PURPOSE: During the course of the development of visual prostheses, subretinal stimulation films were implanted in micropigs in order to prove the feasibility of subretinal electrical stimulation with subsequent cortical response. One aim was to demonstrate that epidural recording of visual evoked potentials is possible in the micropig. METHODS: Film-bound stimulation electrode arrays were placed in the subretinal space of micropigs. This enabled the retina to be stimulated subretinally. Since conventional visual evoked potential (VEP) measuring is virtually impossible in the pig from the neurosurgical point of view, epidural recording electrode arrays were positioned over the visual cortex as permanent electrodes. RESULTS: The feasibility of temporary implantation of film-bound stimulation electrode arrays was successfully demonstrated in the micropig model. On stimulation with monopolar voltage pulses (1000 to 3000 mV), reproducible epidural VEP measurements (5 to 10 micronV) were detected. CONCLUSIONS: The feasibility of subretinal stimulation of the retina was demonstrated in a retinal model that is similar to the human retina. This animal model therefore offers a suitable means of studying the tolerability of stimulation situations in the course of visual prosthesis development.

Animals↗
PubMedDate not supplied

Comparison of low molecular weight heparin and standard heparin in hemodialysis.

The anticoagulant and antithrombotic effect of heparin has been known for many decades. Since low molecular weight heparin has been available, several advantages over standard heparin were observed, especially in long-term use during hemodialysis. In 27 patients, we found a lower bleeding risk, a lower need for erythrocyte transfusions, a lesser increase in activity of various coagulation factors, and lower triglyceride levels. Therefore, low molecular weight heparin would appear to be a good alternative to standard heparin in dialysis patients.

Blood Coagulation Factors↗