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Biomedical subjects

M Rohr

Publications and source records attributed to M Rohr.

At least 19 recordsLinked to original sources
PubMed2006

Influence of applied quantity of sunscreen products on the sun protection factor--a multicenter study organized by the DGK Task Force Sun Protection.

It is often debated that the protection against solar-induced erythema under real conditions is dependent upon the amount of sunscreen applied. It is believed that when too little is applied a lower sun protection than indicated on the label will result. The aim of this study was to quantify this effect. In this multicenter study, the influence of three different amounts (0.5, 1.0, 2.0 mg/cm(2)) of three commercial sunscreen products in three reliable test centers was investigated according to the test protocol of The International Sun Protection Factor Test Method. The main result was a linear dependence of the SPF on the quantity applied. Taking into consideration the volunteer-specific variations, an exponential dependence of confidence interval of the in vivo SPF and amount applied was found. The highest amount applied (2.0 mg/cm(2)) was linked to the lowest confidence intervals. Thus, from the point of view of producing reliable and reproducible in vivo results under laboratory conditions, the recommendation of this multicenter study is an application quantity of 2.0 mg/cm(2).

Confidence Intervals↗
PubMed2004

The subthalamic nucleus in Parkinson's disease: power spectral density analysis of neural intraoperative signals.

To test a new tool for the neurophysiological identification of the human subthalamic nucleus (STN) during stereotactic surgery for the implantation of deep-brain-stimulation (DBS) electrodes, we analysed off-line the intraoperative signals recorded from patients with Parkinson's disease. We estimated the power spectral density (PSD) along each penetration track (8 patients, 13 sides) and determined the spatial correlation of the PSD with the target location estimated from neuroimaging procedures ("anatomical target"), and with the final target location derived from standard intraoperative neurophysiological procedures for STN localization ("clinical target"). At each step we recorded the 'on-line' signal for 120 seconds; because the PSD was estimated by calculating the periodogram for 6-second epochs of neural signal, we had 20 epochs at each step. When the electrode track crossed the STN, the PSD in the 0.25-2.5 kHz band increased, peaking on average <0.5 mm cranial to the clinical target and 1.00+/-1.51 mm caudal to the anatomical target. When the track was outside the nucleus, the PSD remained unchanged. Even on recordings with low signal-to-noise ratio, off-line PSD analysis of neural signals showed a good correspondence with the target indicated by the surgical team. On-line intraoperative estimation of the PSD may be a simple, reliable, rapid and complementary approach to electrophysiological monitoring during STN surgery for Parkinson's disease.

Aged↗
PubMed2003

Intrasphincteric botulinum toxin injection in the treatment of chagasic achalasia.

According to the WHO, 16-18 million people in Central and South America are infected by Trypanosoma cruzi. Chagasic achalasia affects between 7.1% and 10.6% of the population. The aim of this study was to evaluate the effects of Botox injections in the clinical response and esophageal function of patients with dysphagia due to chagasic achalasia. In total, 24 symptomatic patients with chagasic achalasia were randomly chosen to receive Botulinum Toxin (BT) or saline injected by endoscopy in the lower esophageal sphincter (LES). Patients were monitored with a clinical score of dysphagia and an objective assessment (esophagograms, scintillography, manometry, and nutritional assessment) for a period of 6 months. Clinical improvement of dysphagia was statistically significant (P < 0.001) in patients receiving BT when compared with the placebo. There was no significant difference in the placebo group regarding clinical score, LES basal pressure and esophageal emptying time. Esophageal emptying time in the toxin group was significantly lower than in the placebo (P=0.04) after 90 days. There were non-significant increases in esophageal emptying of 25.36% and 17.39%, respectively, at 90 and 180 days, in the BT group (P=0.266). Gender, age, and baseline LES pressure did not influence the response to BT. Our data strongly suggests that intrasphincteric injection of BT in LES is clinically effective in the treatment of chagasic achalasia.

Adolescent↗
PubMed2003

Multiple sequential image-fusion and direct MRI localisation of the subthalamic nucleus for deep brain stimulation.

AIM: Deep brain stimulation (DBS) is the treatment of choice for advanced Parkinson's disease. The target co-ordinates are traditionally calculated in relation to the intercommissural distance. Anterior (AC) and posterior commissures (PC) may be visualised by the means of ventriculography, CT or MRI. METHODS: We have studied the efficacy of direct visualisation of the subthalamic-red nucleus complex on MRI, the advantage of fusion of stereotactic CT and MR images (Multiple Sequences Image Fusion - MuSIF). These methods are combined with double check of indirect calculation of the target co-ordinates based on AC-PC line, as well as the corrispondence to the stereotactic electronic atlas. RESULTS: Subthalamic nucleus (STN) was well recognisable in fused images in all 22 sides. At 3 months from surgery it was possible to reduce 76% of L-dopa equivalent daily dose. Dyskine-sias reduced to 50% and motor fluctuation up to 45%. CONCLUSION: In our experience MuSIF offers very high rate of accuracy in calculation of target co-ordinates. Direct visualisation of STN in MR and MuSIF are reliable and facilitate the accuracy of identification of target co-ordinates. Intraoperative neurophysiological recording increases the accuracy of microelectrode position.

Antiparkinson Agents↗
PubMed2003

Do intraoperative microrecordings improve subthalamic nucleus targeting in stereotactic neurosurgery for Parkinson's disease?

AIM: The clinical importance of intraoperative microrecordings for subthalamic nucleus (STN) localization in neurosurgical practice remains a matter of debate in the various groups. METHODS: To investigate their usefulness in localizing the STN, we retrospectively evaluated how intraoperative microelectrode recordings changed the targeting of the STN estimated only on intraoperative stimulation and neuroanatomic targeting procedures. For neuroradiologic targeting of the nucleus we used a TC-MRI fusion algorithm and direct visualization of the STN. Besides standard microrecordings we also analyzed the power spectral density (PSD) pattern of physiological signals along the track and its neuroanatomic and clinical correlations. RESULTS: In our series of 12 patients with Parkinson's disease undergoing surgery for implantation of deep-brain stimulation (DBS) electrodes in the STN we found that in 25% (1/4) of patients, microrecordings determined the choice of the optimal track. In all the tracks analyzed the PSD peak coincided with the point selected for the final electrode implantation on the basis of the standard procedure for intraoperative monitoring based on both microstimulation and recordings. CONCLUSION: Intraoperative microrecordings are of determinant importance for accurate STN localization and are essential for optimal results in neurosurgical practice. PSD analysis is a simple and quick quantitative signal descriptor that will probably provide even more precise, simple and rapid tool for intraoperative neurophysiological localization of the STN.

Electrodes, Implanted↗
PubMed1996

Results of treatment one year later: child and adolescent partial hospitalization.

OBJECTIVE: One criticism of academicians is that they evaluate and disseminate outcome studies based more on the value and merit of the research design than on the utility of the findings for improving clinical practice. Increasing pressure on programs to evaluate the effectiveness of behavioral health care is transitioning outcome measurement from the exclusive domain of the researcher toward the clinical/organizational domain. To explore the multiple applications of such clinical outcome data, this article presents the results from a study of 114 patients completing treatment in two child and adolescent partial hospital programs. METHOD: Four areas define the scope of clinical outcome measurement pertinent to partial hospitalization: changes in the patient's clinical status, changes in the patient's level of daily functioning, impact on the utilization of behavioral health services after discharge, and patient/family satisfaction with treatment. Using these four domains, this study compares data assessed at admission and at 1 year postdischarge. RESULTS: Analyses used paired t tests primarily to measure change between admission and 1 year after discharge. Overall, the data show improvement in general functioning that remains evident up to 1 year postdischarge. CONCLUSIONS: Finding positive results in specific areas emphasized therapeutically--such as family functioning and use of community-based mental health resources after discharge, and the parent's attribution of improvement to experiences in treatment--provides justification for relating improvement to the treatment episode.

Activities of Daily Living↗
PubMed1995

Stereotactic radiosurgery for recurrent malignant gliomas.

PURPOSE: To evaluate the role of stereotactic radiosurgery in the management of recurrent malignant gliomas. PATIENTS AND METHODS: We treated 35 patients with large (median treatment volume, 28 cm3) recurrent tumors that had failed to respond to conventional treatment. Twenty-six patients (74%) had glioblastomas multiforme (GBM) and nine (26%) had anaplastic astrocytomas (AA). RESULTS: The mean time from diagnosis to radiosurgery was 10 months (range, 1 to 36), from radiosurgery to death, 8.0 months (range, 1 to 23). Twenty-one GBM (81%) and six AA (67%) patients have died. The actuarial survival time for all patients was 21 months from diagnosis and 8 months from radiosurgery. Twenty-two of 26 patients (85%) died of local or marginal failure, three (12%) of noncontiguous failure, and one (4%) of CSF dissemination. Age (P = .0405) was associated with improved survival on multivariate analysis, and age (P = .0110) and Karnofsky performance status (KPS) (P = .0285) on univariate analysis. Histology, treatment volume, and treatment dose were not significant variables by univariate analysis. Seven patients required surgical resection for increasing mass effect a mean of 4.0 months after radiosurgery, for an actuarial reoperation rate of 31%. Surgery did not significantly influence survival. At surgery, four patients had recurrent tumor, two had radiation necrosis, and one had both tumor and necrosis. The actuarial necrosis rate was 14% and the pathologic findings could have been predicted by the integrated logistic formula for developing symptomatic brain injury. CONCLUSION: Stereotactic radiosurgery appears to prolong survival for recurrent malignant gliomas and has a lower reoperative rate for symptomatic necrosis than does brachytherapy. Patterns of failure are similar for both of these techniques.

Actuarial Analysis↗
PubMed1994

Determination of the blood lactate:pyruvate ratio as a noninvasive test for the diagnosis of zidovudine myopathy.

OBJECTIVE: To evaluate the use of the lactate: pyruvate ratio as a test for the detection of zidovudine myopathy. METHODS: Twenty consecutive human immunodeficiency virus-infected patients with muscle involvement and 20 without muscle involvement were studied prospectively. Blood lactate and pyruvate levels and serum creatine kinase levels were tested, muscle involvement was assessed both clinically and electrophysiologically, and muscle biopsy was performed in patients with myopathy. RESULTS: Nine patients had biopsy-proven zidovudine myopathy. All 9 had a high lactate:pyruvate ratio, with elevations on 2 of 2 determinations in 6 patients and on 1 of 2 in 3 patients. Two of 11 patients with other myopathies and 2 of 20 patients without myopathy had a high lactate:pyruvate ratio on 1 of 2 determinations. CONCLUSION: The lactate:pyruvate ratio, when determined repeatedly, is a sensitive test for detecting mitochondrial muscular toxicity of zidovudine.

Adult↗
PubMed1994

Photoinduced volume changes associated with the early transformations of bacteriorhodopsin: a laser-induced optoacoustic spectroscopy study.

Volume changes associated with the primary photochemistry of bacteriorhodopsin (BR) were measured by temperature-dependent laser-induced optoacoustic spectroscopy (LIOAS). Excitation was performed with 8-ns flashes establishing a photoequilibrium between the BR and the K states (BR<-->hvK). The concentration of K at the end of the laser pulse, which is an important parameter for the calculation of the volume change per molecule from the LIOAS data, was determined by flash photolysis with optical detection under the specific conditions (concentration, photon density) of the LIOAS experiment. Temperature-dependent measurements yielded a linear dependency of the ratio of the optoacoustic signals for BR and for a calorimetric reference (CoCl2) with the cubic thermal expansion coefficient beta of water. From the slope of this linear ratio a contraction of 11 cm3/mol was determined.

Bacteriorhodopsins↗
PubMed1990

Changes in the concentration of fructose 2,6-bisphosphate in Aspergillus niger during stimulation of acidogenesis by elevated sucrose concentration.

The presence of fructose 2,6-bisphosphate (Fru-2,6-P2) and phosphofructokinase 2 (PFK 2) were established in the citric-acid-producing filamentous fungus Aspergillus niger. Fru-2,6-P2 levels were around 3.0 (+/- 0.8) nmol per g dry weight during growth on sucrose, and half of this in mycelia grown on citrate as a carbon source. PFK 2 was detected with a specific activity of 150 mU/mg protein and a Km for fructose 6-phosphate of 40 microM. Induction of citric acid accumulation (acidogenesis) in A. niger by cultivation on high concentrations of sucrose, or replacement on 14% (w/v) sucrose correlated with an increase in the intracellular concentration of Fru-2,6-P2. A similar correlation was obtained when A. niger was cultivated on different carbon sources, which induced different rates of acidogenesis. The increase in Fru-2,6-P2 during transfer to 14% (w/v) sucrose was not correlated with the behaviour of mycelial concentrations of cyclic AMP, a potential regulator of Fru-2,6-P2 formation in other organisms, nor with that of Fru-6-P and ATP, the precursors of its formation. The extracellular addition of cyclic AMP and theophylline, an inhibitor of cellular cyclic AMP breakdown, increased both Fru-2,6-P2 concentration and acidogenesis in mycelia cultivated in 1% (w/v) sucrose medium. It is concluded that Fru-2,6-P2 controls citric acid accumulation by enabling increased rates of glucolysis, a prerequisite to acidogenesis.

Adenosine Triphosphate↗
PubMed1989

[Effect of cinnarizine on various types of vertigo. Clinical and electronystagmographic results of a double-blind study].

UNLABELLED: The anti-vertigo effect of Cinnarizine (Stugeron R) has been tested in a controlled double blinded study on 40 patients suffering from various, well defined peripheral or central vestibular disorders. 12 patients out of 20 treated with 75 mg Cinnarizine twice a day during seven days demonstrated satisfactory vertigo suppression versus only 5 out of 20 treated with placebo. ( SIGNIFICANCE: p less than 0.05). Particularly favorable results were obtained in patients suffering from sudden peripheral vestibular deficit, from vertigo of circulatory origin and from post traumatic vertigo. Results were less conclusive in patients with Menière's disease or central neurologic disorders (multiple sclerosis or heredito-degenerative diseases). The difference between the treated group and the placebo group was less striking after a prolonged treatment of eight weeks because of an important spontaneous improvement rate also in the placebo group. Electronystagmography did not show clearly detectable differences between patients treated with Cinnarizine and those treated with placebo. A temporary depressant effect on vestibular nystagmus was however electronystagmographically documented when the Cinnarizine dose was increased to 150 mg, (single dose) given to 5 healthy volunteers. The drug was generally well tolerated. Minor side effects were: slight somnolence (5 patients out of 19), slight headache (2/19) and transient abdominal pain (2/19).

Cinnarizine↗
PubMed1988

[The pharmacokinetics of light-protective agents by photoacoustic spectroscopy].

We report on in vivo investigations by photoacoustic spectroscopy on the liberation and horny-layer penetration of UV-absorbing drugs from topically applied vehicle films. This spectroscopic technique can be used to determine the absorption of light in the skin with a depth resolution adequate for the 12-microns-thick horny layer and to gain information on temporal variations in the concentration profile of drug penetrating into the horny layer. Experimental results are presented for the UV-absorbing drugs Uvinul T 150 and P 25 applied to the skin in different vehicles. The results are discussed with reference to model calculations demonstrating the influence of different rate-determining steps on temporal variations in concentration profiles.

Dose-Response Relationship, Drug↗
PubMed1986

NADP-specific isocitrate dehydrogenase from the citric acid-accumulating fungus Aspergillus niger.

NADP-specific isocitrate dehydrogenase [threo-DS-isocitrate: NADP+ oxidoreductase (decarboxylating), EC 1.1.1.42] was purified 200-300-fold from the citric acid-accumulating fungus Aspergillus niger. The enzyme consists of a single polypeptide chain with a molecular mass of 60 +/- 4 kDa and has a pI of 5.9 +/- 0.2. Only a single enzyme protein was found, although the enzyme appears to occur both in the mitochondrion and in the cytoplasm. Growth on organic acids as carbon sources or on NO3- as nitrogen source led to increased activities, whereas the presence of amino acids led to lower activities. The enzyme exhibits hyperbolic kinetics with respect to its substrates isocitrate and NADP+. Mn2+ and Mg2+ are obligatory for enzyme activity. The enzyme is inhibited by its products alpha-oxoglutarate and NADPH. Among various metabolites, ATP and citrate appear to inhibit the enzyme at a concentration considered to occur intracellularly. In both cases, however, the mechanism is a removal of the metal ion cofactor from the substrates. It is concluded that under physiological conditions, where the Mg2+ content is around 10 mM, the observed inhibition by ATP or citrate is of poor regulatory significance.

Aspergillus niger↗