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Biomedical subjects

K Maurer

Publications and source records attributed to K Maurer.

At least 19 recordsLinked to original sources
PubMed2006

Alois Alzheimer revisited: differences in origin of the disease carrying his name.

Based on the means of his time, Alois Alzheimer supposed that the disease, later carrying his name, is a disease of older age, and that the pathomorphological structures he described are due to disturbances in brain metabolism. In this contribution, it is discussed which cellular metabolic abnormalities may be representative for age-related sporadic Alzheimer disease (SAD) the predominant form of SAD in contrast to the very rare hereditary early-onset form. In focus are disturbances in glucose/energy metabolism which involve the deficits in acetylcholine, cholesterol and UDP-N-acetylglucosamine beside ATP. Another leading abnormality is the defect in cell membrane composition. The interrelation between abnormal glucose/energy metabolism and membrane defect may be assumed to form the basis for the induction of both the perturbed metabolism of the amyloid precursor protein leading to increased formation of beta-amyloid and hyperphosphorylation of tau-protein destroying cell structures. Alois Alzheimer may have been so prescient to assume most of this 100 years ago.

Age of Onset↗
PubMed2006

Apolipoprotein E epsilon 4 is associated with an increased vulnerability to cell death in Alzheimer's disease.

The presumption to suffer from Alzheimer's disease (AD) accelerates with aging. One important risk factor seems to be the isoform epsilon 4 of the apolipoprotein E gene (Apo epsilon 4), which increases the risk to develop AD at an earlier age. Furthermore, convincing evidence is provided that apoptotic cell death mechanisms play an important role in neuronal cell death in AD. In the present study, we investigated whether abnormalities in apoptosis and caspase-3 activity can be found at the level of lymphocytes and a T cell subtype, CD4 T cells, from AD patients compared to aged sex- and ApoE genotype-matched non-demented controls. Under different experimental conditions (at baseline or after in vitro incubation in the presence of proapoptotic stimuli) increased levels of apoptosis and enhanced caspase-3 activity were detected in lymphocytes from AD patients. This difference was most pronounced in the CD4(+) T cell subtype. Notably, we found a significant increase of apoptotic cells and caspase-3 activity in lymphocytes from AD patients bearing one or two alleles of the ApoE4 compared to non-E4 carriers. Again, these effects were strongest in CD4(+) T cells. Circulating amyloid-beta (A beta) levels did not differ between AD patients bearing ApoE4 and non-ApoE4 and age-matched controls. Therefore, it is likely that circulating A beta is not responsible for the observed effects, which might rather reflect an ongoing systemic response in AD, e.g. an increase in CD95 expression.

Aged↗
PubMed2006

[Schizophrenia and depression].

BACKGROUND: Comparison of symptom-related and social role development between patients with schizophrenia, major depression and healthy controls provided insights into the untreated early course of the two disorders. SAMPLES AND METHODS: Symptoms, functional impairment and social disability were assessed and compared using the IRAOS and several other cross-sectional instruments in three samples. RESULTS: At the early illness stages there was considerable overlap in the symptom patterns and impairments presented by persons with schizophrenia and severe depression. The two disorders did not diverge until later in the early illness course with the onset of psychotic symptoms. Depressive symptoms showed a maximum in the first psychotic episode and relapse episodes and decreased with the remitting episode. Due to differences in cognitive appraisal depressed patients reported more functional impairment and social disability than patients with schizophrenia did. CONCLUSION: The early course of symptoms and social impairment in schizophrenia and depression seems to offer an opportunity to distinguish these disorders from variants of normal development fairly early. However, early diagnostic distinction and prediction of psychosis versus depression risk at the pre-psychotic prodromal stage do not seem promising due to the broad overlap in symptoms and impairment.

Adult↗
PubMed2006

Apoptosis of CD4+ T and natural killer cells in Alzheimer's disease.

BACKGROUND: Immunotherapy appears to be a potent treatment against Alzheimer's disease (AD), but the mechanisms underlying neural-immune interaction are still not known. METHODS: Here, we determined cell death and distribution of lymphocyte subsets of peripheral blood mononuclear cells (PBMC) in AD and aging, e.g. T (CD4+ CD3+, CD8+ CD3+), B (CD19+) and NK (CD16++CD56+) cells. RESULTS: Increased apoptosis was found in CD4+ T and NK cells in AD, while in aging all subsets were affected. The expression of anti-apoptotic Bcl2 correlated with observed cell death in T-helper and B cells irrespective of dementia. The levels of Bcl2 in T-cells were significantly increased in mild AD. Apoptosis and Bcl2 levels were also elevated in the APP (751SL)xPS1 (M146L) transgenic mouse model. CONCLUSION: The mechanisms triggering apoptosis and activation of lymphocytes in AD appear therefore to be different than those in immunosenescence and possibly bear an important biomarker to monitor immunotherapy in AD.

Adult↗
PubMed2005

Enhanced ROS-generation in lymphocytes from Alzheimer's patients.

INTRODUCTION: Reactive oxygen species (ROS) have been implicated in neurodegeneration and seem to be involved in the physiology and pathophysiology of several diseases, including normal aging and Alzheimer's disease (AD). Enhanced ROS production in aging or AD is not restricted to the brain, but can also been seen in several peripheral tissues. The objective of the present study was to evaluate whether the mechanisms involved in the generation of oxidative stress in normal senescence and Alzheimer's disease are identical or not. METHODS: We analysed intracellular basal levels of ROS in lymphocytes from AD patients and healthy young and aged not-demented subjects as well as ROS levels following stimulation with d-ribose and staurosporine in all three groups. ROS levels were measured by flow cytometry using the intracellular fluorescence dye dihydrorhodamine123 (DHR123). RESULTS: Our study shows that AD lymphocytes have increased basal levels of ROS, low susceptibility to ROS stimulation by 2-deoxy- D-ribose (dRib) and an increased response to staurosporine when compared with age-matched controls. DISCUSSION: The data suggest that the defect(s) responsible for enhanced ROS production in AD may involve different or additional biological pathways than those involved in enhanced ROS generation during aging.

Adult↗
PubMed2004

Changes in negative symptoms and EEG in schizophrenic patients after repetitive transcranial magnetic stimulation (rTMS): an open-label pilot study.

The effects of repetitive transcranial magnetic stimulation (rTMS) on schizophrenic negative symptoms (NS) and EEG topography were investigated in this pilot study. 10 patients with predominant NS were treated with 10 Hz rTMS over the left dorsolateral prefrontal cortex for 5 days. For NS ratings, the Scale for the Assessment of Negative Symptoms (SANS) was used. Both ratings and EEG recordings were obtained pre- and post-rTMS. Electrical activity changes were computed by Low Resolution Brain Electromagnetic Tomography. SANS showed an improvement after rTMS, from 49.0 (SD: 10.7) to 44.7 (SD: 11.8) (means). EEG frequency bands were changed fronto-temporally (right) and were mainly decreases in delta- and beta- and increases in alpha1-activity, as well as decreases in beta-activity in the temporal and parieto-occipital regions (left). Although we are aware of the limitations of this study, we assume a slight improvement in NS. The EEG findings refer to a possible neurophysiologic correlate of their improvement after rTMS.

Adult↗
PubMed2004

Paintings of an artist with Alzheimer's disease: visuoconstructural deficits during dementia.

Patients suffering from Alzheimer's Dementia (AD) have increasing difficulties to orient in space and often fail to recognize basic realities and even their closest relatives. These symptoms lead to severe deterioration of everyday life and finally to total dependence. In this report we present the case of Carolus Horn, a famous german artist, who contracted with AD. The qualitative and quantitative analysis of changes in his artwork during disease progression gives an impressive insight into the patient's visual world and how it becomes increasingly affected by delusional misperceptions, spatial errors and changes of colour-perception in the course of disease. Carolus Horn's artwork lets us see the world through the patient's eyes and by that it helps us to better understand the consequences of visuospatial and cognitive changes in AD.

Alzheimer Disease↗
PubMed2004

Signal processing and calibration procedures for in situ diode-laser absorption spectroscopy.

Gas analyzers based on tunable diode-laser spectroscopy (TDLS) provide high sensitivity, fast response and highly specific in situ measurements of several atmospheric trace gases simultaneously. Under optimum conditions even a shot noise limited performance can be obtained. For field applications outside the laboratory practical limitations are important. At ambient mixing ratios below a few parts-per-billion spectrometers become more and more sensitive towards noise, interference, drift effects and background changes associated with low level signals. It is the purpose of this review to address some of the problems which are encountered at these low levels and to describe a signal processing strategy for trace gas monitoring and a concept for in situ system calibration applicable for tunable diode-laser spectroscopy. To meet the requirement of quality assurance for field measurements and monitoring applications, procedures to check the linearity according to International Standard Organization regulations are described and some measurements of calibration functions are presented and discussed.

Air Pollutants↗
PubMed2003

Continuous spinal anesthesia/analgesia vs. single-shot spinal anesthesia with patient-controlled analgesia for elective hip arthroplasty.

BACKGROUND: In total hip replacement surgery several anesthesiological techniques can be used. In this study we compared continuous spinal anesthesia (CSA) and postoperative analgesia vs. single-shot spinal anesthesia (SPA) and postoperative patient-controlled intravenous analgesia with morphine (SPA). METHODS: In a prospective randomized study, 68 patients, ASA I-III, between 50 and 85 years of age were allocated to these two groups. Quality of analgesia, hemodynamic stability and technical difficulties, as well as incidence of postoperative nausea and vomiting (PONV) and post dural puncture headache (PDPH), were recorded during a 24-h period. RESULTS: Visual analog scale (VAS) scores were significantly lower in the CSA group from 3 h post operation (P < 0.05). Mean arterial pressure dropped by 21 +/- 11 mmHg in the CSA group and 29 +/- 14 in the SPA group during induction (P < 0.05). Technical difficulties and incidence of PDPH were similar in both groups. Postoperative nausea and vomiting was lower in the CSA group (P < 0.05). CONCLUSIONS: Continuous spinal anesthesia/analgesia is a very practicable method providing better postoperative analgesia and better hemodynamic stability during anesthesia induction than SPA followed by morphine PCA analgesia after total hip replacement surgery.

Aged↗
PubMed2003

Subclinical hyperthyroidism in dementia and correlation of the metabolic index in FDG-PET.

AIM: Thyroid hormone status and thyroid antibodies were evaluated in patients suffering from dementia for further study of an association of hyperthyroidism with AD and vascular dementia (VD), respectively. PATIENTS: In 77 patients with dementia, and 42 controls, thyrotropin (TSH) and thyroid antibodies were correlated with the different types of dementia and the metabolic index (MI) based on imaging with F-18-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET). RESULTS: Twenty-two of all patients with dementia (29%) had borderline (TSH 0.3-0.5 mU/l) or decreased TSH levels (TSH < 0.3 mU/L). TSH values were significantly lower in patients suffering from AD (median: 1.1 mU/l) and VD (0.5 mU/l) than in the control group (1.5 mU/l) (p < 0.01). Decreased or borderline TSH levels were present in 52% of the patients with VD, but in only 10% of the controls, and in 23% of the patients with AD. Antibodies to thyroid peroxidase were positive in 16% of all patients with dementia. The MI in patients suffering from AD with borderline TSH levels was 0.81 (0.70, 0.94). In contrast, patients suffering from AD with normal TSH values showed a slightly higher MI of 0.84 (0.76, 0.89) (p = n.s.). CONCLUSION: Decreased or borderline TSH values are associated with an increased probability of having dementia, especially VD.

Aged↗
PubMed2002

Functional imaging of visuospatial processing in Alzheimer's disease.

Alzheimer's disease (AD) is known to cause a variety of disturbances of higher visual functions that are closely related to the neuropathological changes. Visual association areas are more affected than primary visual cortex. Additionally, there is evidence from neuropsychological and imaging studies during rest or passive visual stimulation that the occipitotemporal pathway is less affected than the parietal pathway. Our goal was to investigate functional activation patterns during active visuospatial processing in AD patients and the impact of local cerebral atrophy on the strength of functional activation. Fourteen AD patients and fourteen age-matched controls were measured with functional magnetic resonance imaging (fMRI) while they performed an angle discrimination task. Both groups revealed overlapping networks engaged in angle discrimination including the superior parietal lobule (SPL), frontal and occipitotemporal (OTC) cortical regions, primary visual cortex, basal ganglia, and thalamus. The most pronounced differences between the two groups were found in the SPL (more activity in controls) and OTC (more activity in patients). The differences in functional activation between the AD patients and controls were partly explained by the differences in individual SPL atrophy. These results indicate that parietal dysfunction in mild to moderate AD is compensated by recruitment of the ventral visual pathway. We furthermore suggest that local cerebral atrophy should be considered as a covariate in functional imaging studies of neurodegenerative disorders.

Aged↗
PubMed2002

[Effect of daily living-related cognitive training on attention and memory performance of persons with dementia].

There are few results of controlled studies about psychological interventions, i.e. training of cognitive functions in dementing illnesses. Most frequently very specific memory strategies are trained, (the effects of) which cannot be generalized to activities of daily living. Thus, a memory training program was developed considering the different cognitive abilities of the participants and which was meant to be generalized to daily tasks. Short-term and long-term memory were trained as well as activities of daily living in 12 lessons for a period of 6 weeks. We can show significant improvements of attention and memory performance in our experimental group in comparison to the control group.

Activities of Daily Living↗
PubMed2002

The experimental combination of rTMS and fMRI reveals the functional relevance of parietal cortex for visuospatial functions.

We combined repetitive transcranial magnetic stimulation (rTMS) and functional magnetic resonance imaging (fMRI) to investigate the functional relevance of parietal cortex activation during the performance of visuospatial tasks. fMRI provides information about local transient changes in neuronal activation during behavioural or cognitive tasks. Information on the functional relevance of this activation was obtained by using rTMS to induce temporary regional deactivations. We thereby turned the physiological parameter of brain activity into an independent variable controlled and manipulated by the experimenter and investigated its effect on the performance of the cognitive tasks within a controlled experimental design. We investigated cognitive tasks that were performed on the same visual material but differed in the demand on visuospatial functions. For the visuospatial tasks we found a selective enhancement of fMRI signal in the superior parietal lobule (SPL) and a selective impairment of performance after rTMS to this region in comparison to a control group. We could thus show that the parietal cortex is functionally important for the execution of spatial judgements on visually presented material and that TMS as an experimental tool has the potential to interfere with higher cognitive functions such as visuospatial information processing.

Adult↗
PubMed2002

Spectroscopic gas analyzers based on indium-phosphide, antimonide and lead-salt diode-lasers.

Currently available semiconductor lasers for spectroscopy in the near- and mid-infrared region based on direct band-to-band transitions as gallium-arsenide, indium-phosphide, antimonides and lead-salt containing compounds will be discussed together with the main features of different tunable diode-laser absorption spectrometers for trace gas analysis. Measurements of atmospheric carbon dioxide with a room-temperature 2 microm indium-phosphide laser, applications of antimonide lasers for methane and formaldehyde sensing in the 3-4 microm range and a fast chemical sensor for methane flux measurements based on lead-salt diode-lasers operating near 7.8 microm will be presented.

Antimony↗
PubMed2002

Bias in computerized neuropsychological assessment of depressive disorders caused by computer attitude.

OBJECTIVE: Psychiatric patients are increasingly confronted to computerized psychological and psychopathological assessment. Patients' attitude to computers was reported to affect acceptance of computerized assessment. METHOD: In 78 psychiatric in-patients neuropsychological impairment was examined following admission on an open ward by conventional as well as computerized memory and attention tasks. Besides psychopathological assessment, self ratings of computer attitude and acceptance of the computerized assessment were completed. RESULTS: A more negative attitude to computers was found to be significantly correlated to higher nervousness in patients' self report (R=0.38, P=0.0005) as well as to poorer results of computerized attention tasks (R=0.39, P=0.0007). Particularly in patients with depressive disorders computer attitude could be shown to explain 39% of the variance of attention performance. CONCLUSION: Results indicate a significant effect of negative computer attitude on acceptance and thus reliability of computerized examination, resulting in a bias in computerized attention-related assessment in patients with depressive disorders.

Adolescent↗
PubMed2001

Multilead quantitative electroencephalogram profile and cognitive evoked potentials (P300) in healthy subjects after a single dose of olanzapine.

RATIONALE: Olanzapine is an atypical antipsychotic drug with a more favourable safety profile than typical antipsychotics with a hitherto unknown topographic quantitative electroencephalogram (QEEG) profile. OBJECTIVES: We investigated electrical brain activity (QEEG and cognitive event related potentials, ERPs) in healthy subjects who received olanzapine. METHODS: Vigilance-controlled, 19-channel EEG and ERP in an auditory odd-ball paradigm were recorded before and 3 h, 6 h and 9 h after administration of either a single dose of placebo or olanzapine (2.5 mg and 5 mg) in ten healthy subjects. QEEG was analysed by spectral analysis and evaluated in nine frequency bands. For the P300 component in the odd-ball ERP, the amplitude and latency was analysed. Statistical effects were tested using a repeated-measurement analysis of variance. RESULTS: For the interaction between time and treatment, significant effects were observed for theta, alpha-2, beta-2 and beta-4 frequency bands. The amplitude of the activity in the theta band increased most significantly 6 h after the 5-mg administration of olanzapine. A pronounced decrease of the alpha-2 activity especially 9 h after 5 mg olanzapine administration could be observed. In most beta frequency bands, and most significantly in the beta-4 band, a dose-dependent decrease of the activity beginning 6 h after drug administration was demonstrated. Topographic effects could be observed for the beta-2 band (occipital decrease) and a tendency for the alpha-2 band (frontal increase and occipital decrease), both indicating a frontal shift of brain electrical activity. There were no significant changes in P300 amplitude or latency after drug administration. CONCLUSION: QEEG alterations after olanzapine administration were similar to EEG effects gained by other atypical antipsychotic drugs, such as clozapine. The increase of theta activity is comparable to the frequency distribution observed for thymoleptics or antipsychotics for which treatment-emergent somnolence is commonly observed, whereas the decrease of beta activity observed after olanzapine administration is not characteristic for these drugs. There were no clear signs for an increased cerebral excitability after a single-dose administration of 2.5 mg and 5 mg olanzapine in healthy controls.

Adult↗
PubMed2001

[Dementia and suicide].

The relationship between suicide and dementia has not systematically been investigated, although the prevalence of both, dementia and suicide, increases with age. In contrast to patients with other psychiatric disorders, patients with dementia were not found to die from suicide more often than expected (SMR, 0). Thus the diagnosis of dementia does not contribute to the elevated suicide risk in old age. In studies using the psychological autopsy method, dementia was rarely diagnosed in suicide victims. Suicide attempts were observed in less than 1% of all patients with dementia. Depression as an important common risk factor of suicide and dementia is often found in patients with Alzheimer's disease (0% to 86%) as well as in patients with multi-infarct dementia (20% to 45%). However major depression was found significantly more often in vascular dementia than in dementia of Alzheimer type. Suicidal thoughts and intents, wishes to die and feelings that life is not worth living were reported in 1% to 42% of all patients with dementia, especially if these patients also suffered from depression. This review comprehensively presents the association between cognitive deficits, insight in early stages of dementia and suicidality and possible confounders which have not systematically been investigated up to now.

Autopsy↗