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Biomedical subjects

N Schäfer

Publications and source records attributed to N Schäfer.

At least 19 recordsLinked to original sources
PubMed2006

The coeliac aneurysm: a rare cause of abdominal pain.

Visceral artery aneurysms (VAA) represent 0.1-0.2% of all vascular aneurysms. For VAA's etiology, congenital or arteriosclerotic factors, media defects, infections, vasculitis and trauma are discussed. Ultrasound, CT scan and magnetic resonance imaging underline the diagnosis of VAA. The low perioperative morbidity and mortality and the excellent surgical longterm results justify the prophylactic therapy also from asymptomatic VAA because the mortality of ruptured VAA is close to 100%. The radiological interventional treatment is indicated for only selected patients whereas an advantage is not verified yet.

Abdominal Pain↗
PubMed2004

DJ-1 (PARK7) mutations are less frequent than Parkin (PARK2) mutations in early-onset Parkinson disease.

BACKGROUND: Mutations in the Parkin gene (PARK2) are the most commonly identified cause of recessively inherited early-onset Parkinson disease (EOPD) but account for only a portion of cases. DJ-1 (PARK7) was recently reported as a second gene associated with recessively inherited PD with a homozygous exon deletion and a homozygous point mutation in two families. METHODS: To investigate the frequency of DJ-1 mutations, the authors performed mutational analysis of all six coding exons of DJ-1 in 100 EOPD patients. For the detection of exon rearrangements, the authors developed a quantitative duplex PCR assay. Denaturing high performance liquid chromatography analysis was used to screen for point mutations and small deletions. Further, Parkin analysis was performed as previously described. RESULTS: The authors identified two carriers of single heterozygous loss-of-function DJ-1 mutations, including a heterozygous deletion of exons 5 to 7 and an 11-base pair deletion, removing the invariant donor splice site in intron 5. Interestingly, both DJ-1 mutations identified in this study were found in the heterozygous state only. The authors also detected a polymorphism (R98Q) in 1.5% of the chromosomes in both the patient and control group. In the same patient sample, 17 cases were detected with mutations in the Parkin gene. CONCLUSIONS: Mutations in DJ-1 are less frequent than mutations in Parkin in EOPD patients but should be considered as a possible cause of EOPD. The effect of single heterozygous mutations in DJ-1 on the nigrostriatal system, as described for heterozygous changes in Parkin and PARK6, remains to be elucidated.

Adolescent↗
PubMed2001

[Local therapy of liver metastases of colorectal carcinomas. Laser therapy vs. direct current treatment in the rat model].

PURPOSE: Evaluation of the efficacy of direct current and laser therapy in the treatment of colorectal liver metastases in a rat model. MATERIALS AND METHODS: Liver metastases in 49 rats were induced by subcapsular injection of cells of a colorectal tumor cell line. 3 weeks after inoculation 41 tumors were treated by laser and 56 tumors by direct current therapy. 17 tumors served as a control in the direct current group, 12 in the laser therapy group. The inoculation rate and the tumor size 3 and 5 weeks after therapy were determined by MRI. RESULTS: The MR-tomographically determined inoculation rate was 133 tumors after 151 tumor cell injections (88%). Three and five weeks after laser therapy, tumor growth rates of 15% and 18% were documented (maximum tumor diameter). This represented a significant reduction in growth (p < or = 0.01 and p < or = 0.001) compared to the control group (growth rate 230% and 280%). In the direct current therapy group, growth rates were 40% after 3 and 60% after 5 weeks. Compared to the control group (210% and 290%), this also represented a significant reduction (p < or = 0.001). CONCLUSIONS: This animal study is the first to demonstrate an antitumor effect of direct-current therapy on liver metastases of colorectal cancer in rats. Nevertheless, the laser therapy proved to be more effective.

Animals↗
PubMed2000

Phosphodiesterase inhibitors and forskolin Up-regulate arginase activity in rabbit alveolar macrophages.

Alveolar macrophages (AMsmall ef, Cyrillic) express considerable arginase activity which can be modulated by various mediators. As inhibitors of phosphodiesterase (PDE) play an increasing role in the treatment of chronic inflammatory and obstructive airway disease, we tested whether PDE inhibitors affect arginase activity in AMsmall ef, Cyrillic. Isolated rabbit AMsmall ef, Cyrillic were cultured for 20 h in the absence or presence of bacterial lipopolysaccharides (LPS) and/or different test substances. Thereafter arginase activity was determined by measuring the formation of [(3)H]-L-ornithine during 1 h incubation with [(3)H]-L-arginine. Lipopolysaccharide-enhanced (0. 01-5 microg/ml) maximal arginase activity by about 2.5-fold. The non-selective PDE inhibitor IBMX and the PDE4 selective inhibitor rolipram (each up to 30 microM) caused a 2.4-fold increase in arginase activity, and these effects were additive to those of LPS. The PDE3-selective inhibitor siguazodan had only marginal effects. Forskolin (10 microM) also enhanced arginase activity in the absence and presence of LPS. The effect of forskolin was almost prevented by cycloheximide (30 microM) and largely attenuated by the protein kinase A inhibitor KT 5720 (300 nM). In conclusion, inhibition of the cAMP-specific PDE4, like direct activation of adenylyl cyclase, causes an up-regulation of arginase activity in rabbit AMsmall ef, Cyrillic.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Results of electrochemical therapy of colorectal liver metastases in rats followed up by MRI.

RATIONALE AND OBJECTIVES: Direct-current or electrochemical therapy is an alternative method for local tumor therapy. Until recently, it was mainly applied in China and was relatively unknown in the Western world. This study examines the feasibility and effectiveness of applying direct-current therapy in liver metastases of colorectal carcinomas in an animal model. METHODS: Liver metastases were implanted in 47 BDIX rats by subcapsular injection of cells from a colorectal strain (DHD/K12). The success rate of implantation and the size of the tumors were determined after 3 weeks by MR imaging (T2-weighted turbo spin-echo images; relaxation time 1,800 ms, echo time 80 ms). The direct-current therapy was applied by one platinum electrode placed in the center of the tumor and four at the periphery of the tumor. Suitable therapy parameters were established in a pilot study by comparing four different methods of direct-current therapy with a control group. The methods varied with respect to the electrode polarity and the applied voltage. In a second series of investigations, tumor growth was monitored by MR imaging 3 and 5 weeks after therapy. RESULTS: The tumor implantation rate was 92.6% at a tumor cell concentration of 8 x 10(5)/mL. The most effective therapy method was achieved by placing an anode at the center of the tumor and four cathodes at the periphery, with an applied charge of 80 C/cm3. Complete tumor necrosis was observed in 54% of cases. In the follow-up measurements, the mean tumor diameter was 0.65 cm at 3 weeks after therapy and 0.76 cm at 5 weeks after therapy. In comparison with the control group (1.08 and 1.53 cm, respectively), this represented a significant reduction in tumor growth rate. CONCLUSIONS: This study is the first to demonstrate an antitumoral effect of direct-current therapy on liver metastases of colorectal cancer in rats.

Animals↗
PubMed1998

PET with 18fluorodeoxyglucose and hexamethylpropylene amine oxime SPECT in late whiplash syndrome.

BACKGROUND: Many patients have cognitive abnormalities and psychological problems after whiplash injury to the cervical spine. To our knowledge, neuroradiologic imaging has not depicted brain damage that explains the symptoms. Parietotemporo-occipital perfusion deficits on hexamethylpropylene amine oxime (HMPAO) SPECT studies have been described among patients who have sustained whiplash injury. METHODS: We examined 13 patients with typical late whiplash syndrome (study group) using HMPAO SPECT, 18fluorodeoxyglucose (FDG) PET, and MRI of the brain and compared the findings with those for 16 control subjects who underwent FDG PET. RESULTS: In the study group, statistical parametric mapping revealed significantly decreased FDG uptake in the frontopolar and lateral temporal cortex and in the putamen. The frontopolar hypometabolism correlated significantly with scores of the Beck Depression Inventory. However, in individual cases, reliability in the depiction of hypometabolic areas was relatively low. No alterations were found in the parietotemporo-occipital area. In these areas, decreased uptake of HMPAO and FDG correlated with cortical mass. CONCLUSION: FDG PET did not allow reliable diagnosis of metabolic disturbances for individual patients. Therefore, we do not recommend FDG PET or HMPAO SPECT as a diagnostic tool in routine examinations of patients with late whiplash syndrome.

Adult↗
PubMed1998

[Pilot study of effectiveness of electrotherapy in the experimental liver metastasis model].

The aim of the present was to assess the effectiveness of low level direct current therapy in liver metastases and the influence of polarity (anode or cathode in the center of the tumor) or current dose (60 or 80 C/cm3). Colorectal metastases were established in 25 BD IX rats by injection of DHD/K12 colon cancer cells under the liver capsule. After 3 weeks the tumors were treated by low level direct current therapy (applied with five platinum electrodes). Histological examination of the removed livers on postoperative day 7 revealed significant destruction of the metastases with localized necroses. The best treatment results were obtained in the group with an anode in the center and a current dose of 80 C/cm3. We conclude that low level direct current therapy may offer an alternative minimal invasive method in the treatment of liver metastases.

Animals↗
PubMed1997

[Use of palm-top computers within the scope of medical data collection and quality assurance].

Computerisation of the medical profession is advancing particularly as the reform of the German medical system is underway and efforts to maintain high quality standards are being made. More and more clinics and private physicians store the data, which they collect in their daily work, in digital form and exchange it via electronic networks. But lacking overall concepts and resistance from monopolistic structures prevent the introduction of innovative technologies, which would allow convenient data collection "on the fly", patterned after proven work routines. This could lead to a real relief from the daily paper work. New approaches using available hard- and software developed abroad demonstrate medical palmtop computing on the Apple Newton.

Data Collection↗
PubMed1996

[Internet--an introduction not only for the physician].

The Internet, a global computer network, is not only a fascinating new media limited to scientists and computer specialist but medical doctors in hospitals as well as private practitioners are increasingly finding interesting applications in their field. Access to data-bases of medical literature, forums dedicated to experts as well as the possibilities of instantaneous electronic data transfer open new possibilities for communication and ongoing education in their everyday work. A serious and yet playful interaction with this new technology offers the chance to prepare for future developments, perhaps to communicate with other physicians, colleagues and institutions using a yet to be founded "German Medical Network". This contribution is particularly suited for colleagues for whom the use of computers is not yet a daily routine.

Computer Communication Networks↗
PubMed1988

Treatment of mild hypertension with urapidil or captopril.

The aim of this study was to compare the efficacy (lowering diastolic blood pressure to 90 mm Hg or less) of urapidil, a postsynaptic alpha-blocker with central action with that of captopril in a randomized, double-blind, multicenter study. Two hundred ninety-five essential hypertensives (WHO I/II) (140 male, 155 female, age 56-60 years) were treated for 12 weeks with either 30 to 90 mg urapidil bid or 12.5 to 50 mg captopril bid. Supine blood pressure values (mmHg, mean +/- SD) at the end of the 12-week treatment dropped for the urapidil group (n = 142) from 175/103 +/- 19/6 to 154/89 +/- 17/9 (P less than 0.001), and in the captopril group (n = 153) from 175/103 +/- 19/6 to 154/90 +/- 19/9 (P less than 0.001), corresponding to 62% urapidil and 58% captopril responder rates. The results demonstrate that the two antihypertensive medications with different modes of action control blood pressure with equal efficacy at three dose levels. A dose decrease was possible in 20% of each group, but a dose increase was necessary in 39% of urapidil and 44% of captopril group.

Adult↗
PubMed1988

Efficacy of urapidil in the management of essential hypertension. A comparison with captopril.

In a multicentre study by general practitioners, the antihypertensive efficacy of urapidil, a postsynaptic alpha-blocker with central action, was compared with that of the angiotensin-converting enzyme inhibitor captopril. The study was of a double-blind, randomised parallel-group design. Following a 2-week washout and placebo phase, 295 essential hypertensives (WHO I/II) were treated for 12 weeks with either urapidil or captopril, initially with urapidil 60 mg twice daily or captopril 25mg twice daily, with the possibility of adjusting the dose according to blood pressure response after 2 weeks of treatment [diastolic blood pressure (DBP) 90 mm Hg or less: reduction of urapidil to 30 mg twice daily or captopril to 12.5mg twice daily; DBP 91 to 99 mm Hg: dose unchanged; DBP 100 mm Hg or more: dose increased to urapidil 90 mg twice daily or captopril 50 mg twice daily]. Blood pressure values at the end of the 12-week treatment period dropped significantly in the urapidil group (n = 142; all dosages) from 175/103 mm Hg to 154/89 mm Hg (p less than 0.001) and in the captopril group (n = 153; all dosages) blood pressure decreased from 175/103 mm Hg to 154/90 mm Hg (p less than 0.001), corresponding to 62% and 58% urapidil and captopril responder rates (DBP less than or equal to 90 mm Hg), respectively. The responder rate at 12 weeks under urapidil therapy was 30% for the initial, 17% for the lower and 15% for the higher dose; the respective values for captopril were 28, 16 and 14%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Acute effects of shock-type vibration transmitted to the hand-arm system.

The aim of the project was to find out whether shock-type vibration of hand-tools compared to non-impulsive vibration has stronger acute effects on the hand-arm system and therefore needs a stricter evaluation from the occupational health point of view in comparison with the requirements of the Draft International Standard ISO-DIS 5349. Under laboratory conditions, subjects were exposed to simulated vibration of hand-tools (grinder, chain saw, hammer-drill, pneumatic hammer, rivet hammer and nailer). The following evaluation criteria were used: biomechanical transmissibility of the hand-arm system (wrist, elbow joint, shoulder joint); muscle-activity (m. flexor carpi ulnaris, m. biceps, m. triceps); peripheral circulation (skin temperature) and subjective perception (comparison of intensity of standard and test vibrations). The results show no significant difference in acute effects on the hand-arm system between impulsive and non-impulsive type vibrations of the hand-tools tested with respect to the chosen vibration level, short-time exposure (up to 8 min) and evaluation criteria. In summary, therefore, it may be concluded that for the evaluation of shock-type vibration of the hand-tools tested, it is justified to use the existing Draft International Standard ISO-DIS 5349.

Adult↗
PubMed1980

[Haemodynamic investigations with the new antihypertensive drug guanfacine (author's transl)].

Guanfacine, a new centrally acting alpha-mimetic antihypertensive drug, was given to two groups of 7 patients each, one with essential and the other with renal hypertension. Both in the acute trial (after short-term intermittent initial blood pressure increase) and in the long-term treatment (4 weeks) lowering of blood pressure occurred, mediated via decrease of peripheral vascular resistance. In addition, support of cardiac function, especially of the afterload and possibly also the preload, was induced. This was demonstrated by results obtained after ergometric loading.

Adult↗
PubMed1980

[Fendiline and isosorbide dinitrate in coronary heart disease (author's transl)].

In a randomized cross-over double-blind study of 30 out-patients with true angina the efficacy of fendiline and isosorbide dinitrate (ISDN) was compared. In randomized order the patients daily took either 3 X 50 mg fendiline or 2 X 20 mg ISDN (plus 1 placebo tablet). Each treatment period lasted for six weeks. Ergometric tests were performed at the onset of the study and at intervals of three weeks. The main criterion for the efficacy of the treatment was a change in S-T segment (at 0.06 s after the QRS). With either drug there occurred a statistically significant reduction in S-T depression and in the frequency of anginal attacks during the first treatment period. But there was a difference between the two drugs: Whereas with ISDN a marked reduction in S-T segment depression was observed after three weeks, this effect slightly receded in the second part of the treatment period, while with fendiline the reduction in S-T depression continued over the entire treatment period. There was no significant difference between the two drugs as to side-effects or tolerance.

Adult↗