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Biomedical subjects

R Engel

Publications and source records attributed to R Engel.

At least 19 recordsLinked to original sources
PubMed2006

Resting state glucose utilization and the CERAD cognitive battery in patients with Alzheimer's disease.

The present study examined the cortical functional representation of neuropsychological domains in Alzheimer's disease (AD) using positron emission tomography (PET) and the neuropsychological assessment battery of the Consortium to Establish a Registry of Alzheimer's Disease (CERAD). Thirty patients with clinical probable AD and 10 elderly healthy controls underwent (18)FDG brain PET imaging during a resting state. Correlations between metabolic values and cognitive measures were determined using a region of interest analysis with NEUROSTAT (University of Michigan, USA) and a voxel-based analysis with SPM96 (Wellcome Department, London, UK). Specific correlations were seen between measures of episodic memory, verbal fluency and naming and left hemispheric temporal and prefrontal metabolism. Drawing was correlated with metabolism in left prefrontal and left inferior parietal regions. The presented data support the use of metabolic-cognitive correlations to demonstrate the neuronal substrates of cognitive impairment in AD. Subtests of the CERAD battery give a good representation of left, but not of right hemisphere function in AD.

Aged↗
PubMed2005

Upper limit on the photon fraction in highest-energy cosmic rays from AGASA data.

A new method to derive an upper limit on photon primaries from small data sets of air showers is developed which accounts for shower properties varying with the primary energy and arrival direction. Applying this method to the highest-energy showers recorded by the AGASA experiment, an upper limit on the photon fraction of 51% (67%) at a confidence level of 90% (95%) for primary energies above 1.25 x 10(20) eV is set. This new limit on the photon fraction above the Greisen-Zatsepin-Kuzmin cutoff energy constrains the -burst model of the origin of highest-energy cosmic rays.

Journal Article↗
PubMed2005

Detection and imaging of atmospheric radio flashes from cosmic ray air showers.

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.

Journal Article↗
PubMed2005

Prescribing practices in German and Swiss psychiatric university and in non-university hospitals: national differences.

OBJECTIVE: There are great variations between hospitals in the way drugs are prescribed, and these variations may be due to multiple factors such as local prescribing traditions, pharmacoeconomic considerations, drug availability, regional differences of population, disease prevalence etc. Available studies on prescribing habits, apart from studies performed in a unique center, have until now been mainly restricted to single countries or regions and the comparisons across countries or regions have often been limited by the use of diverse methodologies and definitions. The aim of the present study was to compare drug prescriptions between German and Swiss psychiatric services with regard to their preference of newer psychotropics. MATERIAL AND METHODS: Five psychiatric hospitals, associated to the AMSP project, were chosen to represent Swiss and German clinics, university and non-university settings. Data were available from one index day on 572 patients and 1,745 prescriptions. The comparisons were adjusted for age and gender. RESULTS: There was a significant difference (p < 0.001) with regard to the prescription of newer antidepressants (NAD), Swiss clinicians giving proportionally more (65.2%) than the German psychiatrists (48.3%). No significant difference was, on the other hand, found as to the proportion of atypical antipsychotics, the lack of difference being due to the higher proportion of clozapine among the atypical antipsychotics in Germany. CONCLUSION: There seems, therefore, to be a higher propensity for Swiss hospital psychiatrists to prescribe newer antidepressants. This seems to be due to national or regional prescribing traditions. Further studies are needed to investigate the economical influences on antidepressant prescribing in Swiss and German clinics.

Adolescent↗
PubMed2004

Severe and uncommon involuntary movement disorders due to psychotropic drugs.

Disorders of involuntary movement due to psychotropic drugs pose a major problem when treating mentally ill patients. These adverse drug reactions (ADR) frequently undermine the patients' compliance and may have serious consequences as well. The drug safety program in psychiatry AMSP (Arzneimittelsicherheit in der Psychiatrie) surveyed a population of 122,562 patients between 1993 and 2000, and documented 129 especially severe or uncommon involuntary movement disorders (IMD): 9 episodes of severe acute dyskinesia, 32 of severe Parkinsonism, 5 of especially severe akathisia, 16 of 'atypical dyskinesia', 38 of Pisa syndrome, 6 of catatonic neuroleptic syndrome, 15 of neuroleptic malignant syndrome, and 8 of tardive dyskinesia. The epidemiological data for this population were systematically analyzed as regards the patient's history of medication, comedication, and clinical course. In those cases, in which a certain drug was imputed to cause an ADR alone and the causal relationship was rated as definite or probable, typical neuroleptics with mainly antipsychotic effects showed a relatively high incidence of 0.1047 %, those with hypnotic-sedative effect a lower incidence of 0.0198 %, and the atypical neuroleptics an incidence of 0.0567 %. This difference was highly significant in an chi (2)-analysis (chi (2) = 18.81, df = 2, p < 0.0001). Our data provide important information on the frequency, severity, and the consequences of ARD for the patients' compliance, and thus are of clinical interest.

Adult↗
PubMed2004

Blood dyscrasias induced by psychotropic drugs.

Drugs can cause a variety of blood dyscrasias, e. g., by interfering with hematopoiesis in the bone marrow or damaging mature blood cells by antibodies. Although numerous reports on the risks of adverse hematological effects associated with psychotropic drugs have led to stringent monitoring requirements for some compounds, particularly neuroleptics, it is still difficult to estimate the true prevalence of such risks. Sixteen episodes of thrombocytopenia, 63 of neutropenia, 22 of agranulocytosis, 4 episodes of severe neutro- and thrombocytopenia, and 2 of pancytopenia were documented by the drug safety program in psychiatry AMSP (Arzneimittelsicherheit in der Psychiatrie) in a population of 122,562 patients between 1993 and 2000. All cases were related to the epidemiological data provided for this population and systematically analyzed as regards history of medication, co-medication, and the clinical course. Putative risk rates for the main groups of medications and a number of drugs could be estimated with this database. Most changes in the white blood cell counts, which were rated as probably or definitely drug-induced, were attributed to clozapine (0.18 % of patients exposed), carbamazepine (0.14 %) and perazine (0.09 %). In patients on newer atypical neuroleptics, we documented neutropenia assumed to be probably or definitely drug-related in five patients during treatment with olanzapine and in one case with risperidone. In all five olanzapine-related cases, the drugs were the sole cause of the adverse drug reactions. All surveyed patients who received clozapine showed no difference in age and gender distribution from those who developed hematological changes. Incidences of hematological changes for antidepressants were much lower (about 0.01 %). Although the methodological accuracy of these findings has to be critically discussed these data could be of considerable clinical relevance and should be helpful in making clinical treatment decisions.

Adult↗
PubMed2004

Mycobacterium bovis tuberculosis: from animal to man and back.

Rare cases of tuberculosis due to Mycobacterium bovis have been described in humans who have been exposed to cattle or other infected animals. We report a case of tuberculosis in cattle exposed to a patient infected with M. bovis, where the strain isolated in the cattle and the patient were identical. As the patient is reported to have been exposed and contaminated during childhood, this seems to be the first documented case of transmission of M. bovis from animal to man and back to animal.

Aged↗
PubMed2003

Effects of scopolamine on matching to sample paradigm and related tests in human subjects.

This was a double-blind placebo-controlled study with a cross-over design to examine the effects of scopolamine on cognitive functions in young healthy subjects. Scopolamine hydrobromide was administered subcutaneously to 12 subjects (mean +/- SD age 23.8 +/- 2.2 years) at doses of 0.3 and 0.6 mg in comparison with two placebo conditions. Scopolamine at both doses produced marked sedation as rated by subjects and an observer. In the continuous performance test, vigilance was impaired by both doses of scopolamine. The span of apprehension test showed differing results (only the high dose of scopolamine showed a performance decrement only in the three-character version of the span of apprehension test). Significant impairment by both doses of scopolamine was seen in immediate and delayed free recall, continuous visual recognition, running word recognition and running picture recognition. While scopolamine caused a significant slowing in average reaction times for simultaneous matching as well as for delayed matching, subjects made more errors under scopolamine compared to placebo only in delayed matching, not in simultaneous matching. Also, the main outcome of matching to sample showed significant effects only in delayed matching, not in simultaneous matching. Notable in this study is the incongruity between the simultaneous matching test and the span of apprehension test on the one hand and the other cognitive tests used on the other. These results demonstrated that scopolamine has a greater effect on memory than on attention. Thus, the scopolamine-induced effects in the present study seem to be more relevant to Alzheimer's disease in an advanced phase than to normal aging.

Adult↗
PubMed2002

CSF tau protein phosphorylated at threonine 231 correlates with cognitive decline in MCI subjects.

In this longitudinal study of 77 patients with mild cognitive impairment (MCI), the authors analyzed whether levels of tau protein phosphorylated at threonine 231 (p-tau(231)) in CSF correlate with progression of cognitive decline. High CSF p-tau(231) levels at baseline, but not total tau protein levels, correlated with cognitive decline and conversion from MCI to AD. Independently, old age and APOE-epsilon 4 carrier status were predictive as well. Our data indicate that an increased p-tau(231) level is a potential risk factor for cognitive decline in patients with MCI.

Adult↗
PubMed2001

A model of microbial contamination of a water reservoir.

A three year record of daily fecal coliform counts in a Massachusetts water reservoir has the appearance of an irregular time series punctuated by outbursts of varying duration. The pattern is described in terms of a probabilistic model where the fluctuations in the 'regular' and 'explosive' regimes are governed by two sets of probabilities. It has been assumed that the random oscillations has a lognormal distribution, and that once an explosion threshold has been exceeded the increments or decrements in the population size have fixed probability distributions. The threshold for triggering an outburst was estimated by examining the randomness of the autocorrelation function of the record after it is filtered to eliminate peaks of progressively increasing magnitude. Once the threshold has been identified, the mean and standard deviation of the underlying lognormal distribution could be estimated directly from remains found in the record after all the peaks were removed. The probabilities of an increment and decrement during the outbursts and their relative magnitudes could also be estimated using simple formulas. These estimated parameter values were then used to generate realistic records with known threshold levels, which were subsequently used to assess the procedure's feasibility and sensitivity.

Computer Simulation↗
PubMed2001

Polymorphisms in the apolipoprotein E (APOE) gene in gerontopsychiatric patients.

Two recently described polymorphisms in the promoter region of the apolipoprotein E (APOE), the -491A/T and Th1/E47csT/G polymorphism, have been suggested to be associated with an increased risk for Alzheimer's disease (AD) independent from the APOE epsilon 4 carrier status. We studied the association between the APOE epsilon 4 polymorphism and the -491A/T and Th1E47csT/G polymorphisms in a sample of 118 healthy, non-demented controls and 239 consecutively recruited gerontopsychiatric patients diagnosed as: Alzheimer's disease (N = 89), age mild cognitive impairment (N = 32), memory complainers without any cognitive deficit (N = 54) and depression/other psychiatric disorders (N = 64), to test whether the investigated polymorphisms have a high enough selectivity and specificity to distinguish between the different gerontopsychiatric disorders or to differentiate AD genetically from other forms of dementia, respectively. Also a possible association with the APOE epsilon 4 polymorphism was examined. We found a statistically significant association between the APOE epsilon 4 allele and Alzheimer's disease (p = 0.0001) and age associated memory impairment (p = 0.006). Our study failed to show an association between the promoter polymorphisms -491A/T and Th1E47csT/G in the APOE gene and gerontopsychiatric disorders either alone or in relationship to the APOE epsilon 4 polymorphism. However, if we combine our results with three previous published positive reports there seems to be an association between the -491A/T polymorphism and AD, though its size is less than found in the original publication.

Aged↗
PubMed2001

["Data for action" from the viewpoint of the Regional Dental Board and the Regional Professional Group for Dental Health].

Lecture by the President of the Landeszahnärztekammer (Regional Chamber of Dental Surgeons) Baden Wuerttemberg and Chairman of the Landesarbeitsgemeinschaft Zahngesundheit (Regional Task Force for Dental Health) on the occasion of the 50th scientific convention "Healthy into the Future" of the Federal Association of Doctors and Dentists in the Public Health Sector. This lecture by Dr. Rüdiger Engel highlights the planned goals of the Landesarbeitsgemeinschaft Zahngesundheit (Regional Task Force for Dental Health) as well as those of the 37 associated Regional Task Forces for Dental Health up to year 2003.

Data Collection↗
PubMed2000

Cell density-dependent VP-16 sensitivity of leukaemic cells is accompanied by the translocation of topoisomerase IIalpha from the nucleus to the cytoplasm.

The resistance of several leukaemic and myeloma cell lines (CCRF, L1210, HL-60, KG-1a and RPMI 8226) to VP-16 was found to increase with cell density and to be maximal (3.5- to 39-fold) in plateau phase cell cultures, as measured by clonogenic and MTT assays. Non-transformed confluent Flow 2000 human fibroblasts and Chinese hamster ovary (CHO) cells were also five- and 15-fold resistant to VP-16 respectively. The transition from log to plateau phase was accompanied by a drastic decrease in topoisomerase (topo) IIalpha content in CHO cells and human fibroblasts, while the leukaemic cells maintained constant cellular levels of topo IIalpha and topo IIbeta. However, the nuclear topo IIalpha content was found to decrease as a result of translocation of the enzyme to the cytoplasmic compartment in the leukaemic cells. This was confirmed by subcellular fractionation experiments, Western blotting analyses and immunocytochemistry studies. The quantity of topo IIalpha in plateau phase cytoplasmic fractions ranged from 18% in L1210 cells to 50% in HL-60 and 8226 cells, as measured by both immunoblotting and quantification of the label in immunofluorescent images. The cytoplasmic fraction from plateau phase cells retained topo II catalytic activity, as measured by the decatenation of kinetoplast DNA. The nuclear-cytoplasmic ratio of topo IIalpha may be critical in determining the sensitivity of leukaemic cells to topo II inhibitors. Cytoplasmic trafficking of topo IIalpha was observed in plasma cells obtained from patients with multiple myeloma, and perhaps contributes to drug resistance in this disease.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Polycations. 5. Inducement of psi-DNA circular dichroism signals for duplex deoxyribonucleotide homopolymers by polycationic strings.

Atypical circular dichroism intensity enhancements previously associated with Psi-DNA condensates are reported for poly(dG-dC):poly(dG-dC) and poly(dA-dT):poly(dA-dT) upon addition to them of a polycationic string salt. Polycationic strings are organic species incorporating several cationic sites in a linear array through the molecule. The effect observed herein with a small molecule model system holds promise for elucidation of the structural details associated with Psi-DNA condensate formation.

Cations↗
PubMed1999

Inhibition of food intake in response to intestinal lipid is mediated by cholecystokinin in humans.

Intraduodenal fat inhibits gastric emptying and exerts early satiation in animals and humans, but it is not clear whether the effects are mediated by cholecystokinin (CCK) in humans. Here, we tested whether CCK-A receptors mediate the inhibition of fat on food intake. Two sequential, double-blind, crossover studies were performed in 24 male subjects. First, subjects received either intraduodenal fat or saline together with a preload of either water or banana shake. Second, 12 subjects received either intraduodenal fat or saline perfusion plus a concomitant infusion of saline or loxiglumide, a specific CCK-A receptor antagonist, together with a preload of banana shake. In both studies, subjects were free to eat and drink as much as they wished. Fat induced a reduction in calorie intake (P < 0.05) compared with controls. Furthermore, a decrease in hunger feelings was observed. Infusion of loxiglumide abolished the effects of fat. Duodenal fat interacts with an appetizer to modulate energy intake in humans. This effect is mediated by CCK-A receptors.

Adult↗
PubMed1998

Something new in the field of PLA/GA bioresorbable polymers?

Polymers issued from glycolic acid and lactic acids (PLAGA) are now used worldwide as bioresorbable devices in surgery and in pharmacology. Their abiotic hydrolytic degradation has been shown to depend on diffusion-reaction phenomena and to proceed homogeneously or heterogeneously, depending on many factors. Two initiators are presently used industrially to make PLAGA polymers by ring opening polymerisation of lactide and/or glycolide in the bulk, namely Sn octanoate and zinc metal. In this contribution, attention is paid to the differences generated by the use of these two initiator systems in the case of the polymerisation of DL-lactide. Various poly(DL-lactide)s were prepared and characterised by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (NMR). These polymers were allowed to age in pH=7.4 isoosmolar phosphate buffer at 37 degrees C. Under these conditions, polymers prepared by the two initiator systems showed dramatic differences when the fates of parallel sided specimens of rather large dimensions were considered. These differences were related to the esterification of some of the OH chain ends by octanoic acid and to the presence of rather hydrophobic low molecular weight by-products which were insoluble in the solvent generally used to purify the crude PLAGA polymers. These new findings should be of great interest in the case of PLAGA based matrices aimed at drug delivery.

Biocompatible Materials↗
PubMed1998

Risk factors for suicides of inpatients with depressive psychoses.

Research on identifying the relevant risk factors for suicides is faced with a multitude of methodological problems. The present study attempts to improve on some of these problems and to isolate those risk factors that are accessible in the early stages of the treatment of inpatients. A total of 3792 inpatients with monopolar or bipolar depression were treated during the period 1981-1992. Suicides (n=33) and controls (n=3759) were compared with respect to 77 sociodemographic and anamnestic variables and 195 standardised items of the admission summary. In addition to an analysis of contingency tables a discriminant analysis was performed. The suicide rate of patients with depressive psychosis was 2.7 times higher than the average rate of 0.324% for the entire clinic. Suicidal tendencies on admission proved to be the best predictor with a frequency of 91% in the suicide group and 40% in the control group, previous attempted suicide being the second best predictor. We conclude that the rate of inpatient suicide may have been underestimated for methodological reasons in the past decades. Many of the risk factors discussed in the literature may be of little predictive value at least in the initial stages of hospital treatment.

Adult↗