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Biomedical subjects

E Hempel

Publications and source records attributed to E Hempel.

At least 19 recordsLinked to original sources
PubMed2006

Functional outcome after gamma knife treatment in vestibular schwannoma.

Radiosurgery (RS) is a noninvasive, ambulatory special neurosurgical procedure for the treatment of vestibular schwannoma (VS). We treated 123 patients with unilateral schwannomas between 1994 and 2000 at the gamma knife (GK) center in Munich using a primary stereotactic procedure. These patients were followed up until June 2004 in respect to audiological, neurological, neurootological and radiological features before and after radiosurgical intervention. The actual tumor control rate of 8.2 years (mean) after GK surgery for all patients and a single treatment was calculated to be 96.7%. The impairment of hearing was on average 18% after GK, ranking from 0% gain of hearing loss up to 90%. Facial nerve function, graded according to the House-Brackmann scale, deteriorated in none of the patients; 5.8% reported a trigeminal neuralgia. Tinnitus developed in 4.1% of the patients after RS; 13.3% had vertigo for the first time after the treatment, age apparently being a predisposing factor. Radiosurgical treatment for VS is an alternative to microsurgery (MS). It is associated with a lower rate of facial and trigeminal neuropathy, postoperative complications and hospital stay. The hearing preservation rate is equivalent to MS.

Adult↗
PubMed2002

[Development of an optical 3-D position measuring system for simultaneous detection of 6 degrees of freedom].

A few years ago it became possible to carry out complicated surgical procedures in humans with the required precision by combining medical imaging (MRI, CT) with minimally invasive surgery. The confined space within these imaging systems and the resulting inaccuracies associated with the manual use of instruments increasingly make necessary the help of aids ranging from positioning systems to robotic devices, which themselves must be position controlled. A position sensor has been developed for a medical robotic system allowing the image-controlled insertion of injection needles and the simultaneous administration of different drugs. The 3D position coordinates are determined by a noncontact optical principle, which also enables simultaneous determination of all 6 basic degrees of freedom of the robotic system (3 translational, 3 rotational). On the basis of an area image sensor and the measurement of a geometrically defined structure in the path of the rays between sensor and light source, the position coordinates are calculated almost real time. Special emphasis was placed on designing the sensor system to cover a sufficiently large workspace to enable it to cover the entire intervention area. The sensor described herein determines the position coordinates in a volume of 10 x 10 x 10 cm at a resolution of up to 1 mm for translations and 1 degree for rotations.

Equipment Design↗
PubMed2000

Robust localization of the contralateral precentral gyrus in hemiparetic patients using the unimpaired ipsilateral hand: a clinical functional magnetic resonance imaging protocol.

Tumor related contralateral motor deficits complicate preoperative functional magnetic resonance imaging (fMRI). In plegic patients the localization of the sensorimotor cortex is often impossible. In this context we developed a clinical fMRI protocol dedicated to patients with motor deficits using the unaffected ipsilateral hand. Based on the hypothesis that selfpaced finger movements recruit more and larger neuronal populations with rising task complexity, different motor tasks were tested regarding ipsilateral localization in ten right handed volunteers. Complex finger opposition localized the ipsilateral premotor cortex (Brodman area 6) robustly and was introduced to preoperative fMRI in hemiparetic patients as functional landmark to identify the precentral gyrus on the tumors side. Additional contralateral automated tactile stimulation localized the primary somatosensory cortex and completed the protocol.

Adult↗
PubMed1999

Somatotopic mapping of the human primary somatosensory cortex by fully automated tactile stimulation using functional magnetic resonance imaging.

The clinical application of functional magnetic resonance imaging (fMRI) requires time-saving protocols insensitive to artifacts that provide robust localization and important information on brain function. A fully automated, pneumatically driven tactile stimulation is presented, that reproducibly localizes postcentral lip, finger and toe representations in contralateral primary somatosensory cortex (SI) with mean correlation coefficients (cc) and relative BOLD signal changes (dS) of cc approximately 0.59, dS approximately 1.95% (fingers); cc approximately 0.52, dS approximately 1.35% (lips); cc approximately 0.47, dS approximately 1.42% (toes). Bilateral somatotopic mapping requires 21 min of scanning time and has become a clinical routine fMRI application in patients with perirolandic tumors. Normative data may also be useful in monitoring cerebral plasticity and reorganization, e.g. in sensorimotor recovery after cerebral ischemia or in understanding mechanisms of supraspinal pain processing.

Adult↗
PubMed1999

[The effect of the stimulus frequency, stimulus amplitude and blood pressure on the signal response in functional MRT: studies on an animal model].

PURPOSE: To examine the influence of frequency and amplitude of a stimulus and the effect of blood pressure on signal intensity changes in functional MRI. METHODS: Somatosensory stimulation of five (normotonic/hypotonic) anesthetized rats was performed with different stimulus frequencies and amplitudes. Measurements were performed with a 2.4 Tesla experimental scanner using a gradient-echo (GE) echo-planar imaging (EPI) sequence. RESULTS: The highest signal change was found at a frequency of 3 Hz and a stimulation amplitude of ten times the threshold value. A decrease of blood pressure to half the normotonic value gave rise to a decrease of the neuronal response of about 17%. CONCLUSION: Optimization of the stimulation frequency and stimulation amplitude maximizes signal changes in functional MRI of the somatosensory cortex. Even with a standardized paradigm, variations in measured neuronal activity may occur when blood pressure changes cannot be compensated by autoregulation.

Animals↗
PubMed1995

[Changes in life expectancy and mortality in East Germany after reunification (1989-1992)].

Whereas some arguments can be advanced suggesting that the life expectancy in east Germany should have declined directly after the fall of the Berlin Wall in 1989, other arguments suggest an increase. The aim of this study was to identify the actual developments and to explain the findings. Census data and mortality statistics from East and West Germany before unification were used to calculate standardized mortality ratios and life expectancies for various population groups. The differences in life expectancy between East and West were broken down according to age groups. The main finding was that the life expectancy of east German men declined in 1990 by 0.9 years, and only reached the 1989 level again in 1992. This was due solely to an increase in mortality for men under the age of 65. In 1990 and 1991, there were 3,400 more deaths among men under the age of 65 than would have been expected on the basis of the mortality rates of 1989. In contrast, the life expectancy of women hardly declined at all in 1990, and in 1992 it was already one year more than for 1989. The most important reasons for the increased numbers of deaths of men under the age of 45 were motor vehicle accidents, whereas ischaemic heart disease and cirrhosis of the liver were more significant for men between the ages of 45 and 65. Suicides did not increase after the fall of the Berlin Wall. It could be shown that the findings were not the results of artifacts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Effect of levonorgestrel and ethinyl estradiol and their combination on biotransformation reactions].

Caffeine is mainly metabolized by 3-methylcholanthreneinducible cytochrome P-450, whereas metamizol (Analgin) is probably mainly metabolized by the phenobarbital inducible cytochrome P-450 family. Therefore the elimination of caffeine from serum and the elimination of the main metabolites of metamizol in urine reflect the activity of these two cytochrome P-450 families. Sex hormones can influence the activity of cytochrome P-450. Intake of levonorgestrel (0.125 mg) daily for 14 days reduced the metabolism of caffeine slightly, but the elimination of metamizol-metabolites is not influenced. Longterm administration of levonorgestrel (0.250 mg daily) for three months did not change the metabolisms of both model substances tested. In contrast, ethynylestradiol (0.050 mg) alone and also the combination with levonorgestrel markedly retarded the elimination rate of caffeine and metamizol-metabolites. This fact should be taken into consideration in drug therapy.

Adult↗
PubMed1991

[Experiences in the control of brucellosis in cattle herds in the government district of Hannover].

Caused by imported beef cattle new outbreaks of Brucellosis (subtype III) were observed in the government district of Hannover, which was "Brucellosis free" over a long period. With the aim to interrupt the series of infections from herd to herd it seemed to be necessary to introduce a herd screening system including frequent tests. It was not possible to screen the herds by the usual way of blood serum testing because of reasons of practicability and economy. A practicable alternative was the ELISA supported tank investigation. Four of the last six outbreaks were detected by this milk sampling. The other two infected herds were detected by only clinical symptoms because the lactating cows were not infected and had no contacts to the infected separately held heifers. The required test frequency in the dairy cattle herds could only be realized applying an ELISA supported highly sensitive tank milk test method. This method offered the chance of discovering infected herds as soon as possible and prevented greater economical losses and animal health risks. The tank milk screening of the dairy cattle herds to detect antibodies against Brucellosis (and additional EBL and IBR) has now become a standard method to continue the official status "free from..." This is a safer and a more economic alternative to the previous blood sampling of cattle older than two years with a three years interval because this method guarantees a safe information about the serological status of each cow which is now tested at least once a year, depending on the time of dry standing status.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Occlusive therapy of psoriasis--comparison of clinical effectiveness of short-term and prolonged use].

In an open clinical trial on stationary psoriatic plaques, we compared the effects of shortime occlusive (SO) dressing (24h) and prolonged occlusion (PO: 5-28 days). IN SO, Weinstein's index decreased from 7.3 +/- 1.7 to 3.3 +/- 1.8 (n = 21), in PO from 6.5 +/- 1.1 to 3.7 +/- 1.7 (n = 15). The results were even better in cases with optimal PO dressing (decrease from 6.8 +/- 1.4 to 2.5 +/- 0.9). The most important side effects were itching and exsudation with ensuing smell. In only one of the cases did the side effects cause a drop-out after 5 days. Regarding stationary psoriatic plaques on the extensor sides of the lower legs and forearms. We recommend continuous occlusive dressing for 8-10 days--either as an alternative mode of therapy, or as an intermediate regimen.

Adolescent↗
PubMed1988

[Comparison of the progesterone test and uterus sonography as screening procedures in the detection of patients at risk of endometrial cancer].

The increasing incidence of endometrial cancer requires more attention to early detection. Postmenopausal women without symptoms were examined by progesterone challenge test (96 diabetics, 111 without diabetes) and by sonography (44 diabetics, 74 without diabetes) in order to recognize proliferation of the endometrium. The application of progesterone induced a bleeding in 4% of the women. The diagnostic curettage performed 4-6 weeks after this test revealed almost always atrophic endometrium. We found a good correspondence between abnormalities of the uterine cavity detected by sonography and the results of the pathological examination after notice pathological changes of the endometrium.

17 alpha-Hydroxyprogesterone Caproate↗
PubMed1987

[Behavior the lipid spectrum following complete ovariectomy and subsequent substitution with estradiol valerate or norethisterone acetate].

In a prospective trial the effects of oophorectomy and following administration of estradiol valerate (2,0 mg/day) or norethisterone acetate (5,0 mg/day) on the blood lipids were investigated during the late postoophorectomy time. After complete ovarectomy 52 women (42-49 years old) were randomized in two groups and substituted with these steroids from the 7. to 12. month after operation. Before total estrogen excretion/24 h urine, serum levels of estradiol and testosterone and the maturation value were studied. The blood levels of total-, HDL- nnd LDL cholesterol and triglycerides were markedly higher 2 and 6 months after castration than before. Norethisterone acetate depressed transitorily the total cholesterol and longer the HDL cholesterol, the triglycerides were increased 6 months after administration. A long lasting norethisterone acetate substitution in postmenopausal women should be below 5 mg/day.

Adult↗
PubMed1984

[Application possibilities of an automatic image analyzer ("Quantimet 720") in bone histomorphometry].

By the way of proofing of the preventive estrogen effect on the ovariectomy osteoporosis in rats the authors collected experiences in measuring of two histomorphometric parameters "trabecular bone volume" and "trabecular bone surface" with the automatic image analyser Quantimet 720. This method demands thin bone polishes or cuts, a very rich in contrast and selective colouring. The measurement with this device spares time and gives reliable results for "trabecular bone volume", but less reliable values for "trabecular bone surface".

Analysis of Variance↗
PubMed1981

[Behaviour of Butanol-extractable iodine in serum, during and after long-time application of hormonal contraceptives (author's transl)].

The behaviour of butanol-extractable iodine in serum was tested, during and on completion of administration of Non-Ovlon, Ovosiston, Gravistat, and Deposiston, the latter being a longacting contraceptive. Action of synthetic sexual steroids led to an increase in butanol-extractable iodine. However, this change proved to be easily reversible, soon after the end of medication, even after long-time application. Yet, complete normalisation should not be expected to occur before the second cycle without contraceptives, which applies, in particular, to women who had been on long-acting contraceptives.

Adult↗
PubMed1980

[Studies into effects of intra-gestational hypotension and maternal Broca's index on birth weight (author's transl)].

Studies were conducted into the effects of intragestational hypotension and Broca's index of mothers on the birth weights of newborns, with reference being to intensive pregnancy care documentation filed for the years 1977 through 1979 at the Gynaecological Hospital of Friedrich-Schiller-Universität Jena, GDR. The low birth weights quoted in literature were not confirmed by the data available to the authors. - Yet, close relationship was found to exist between the mother's relative Broca's index and birth weight. Hence, that factor should be taken into due consideration, whenever studies are undertaken into the problem of newborns with low birth weight.

Birth Weight↗