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Biomedical subjects

P Kirsch

Publications and source records attributed to P Kirsch.

At least 19 recordsLinked to original sources
PubMed2006

[The importance of anamnesis in differential diagnosis of reflex and cardiogenic syncope].

UNLABELLED: The aim of the study was to establish the difference in the anamnestic data in cardiogenic and reflex syncope during a systematic gathering of data using a structured questionnaire and to measure the benefits of structured clinical history in differential diagnosis of syncope. METHODOLOGY: 70 patients with syncope of undetermined etiology (average age 51 years, 26 men and 44 women) underwent a standard diagnostic protocol procedure. Cardiogenic syncope was diagnosed in 16 patients (23%), vasovagal syncope in 34 patients (49%), in 20 patients (28%) the cause of the syncope remained uncertain. Anamnestic data was collected through a structured questionnaire which contained 70 points. OUTCOME: Patients with cardiogenic syncope, as opposed to those with vasovagal syncope, tended to show higher age (68 vs. 43 years, p < 0.001), higher occurrence of IHD (75% vs. 35%, p = 0.008) and hypertension (62% vs. 29%, p = 0.02). Cardiogenic syncope in the prodromal phase exhibited a more frequent feeling of weakness (43% vs. 14%, p = 0.02), absence of the typical provoking factor (56% vs. 15%, p < 0.001), unspecific occurrence during the day (81% vs. 41%, p = 0.008), and weak pulse according to witness report (50% vs. 8%, p = 0.01). There was a significantly higher incidence of visual disturbances in vasovagal syncope in the prodromal phase (47% vs. 19%, p = 0.05) and sweating (29% vs. 6%, p = 0.05), provoking factors often involved long standing on feet (66% vs. 25%, p = 0.01) and hunger (29% vs. 0%, p = 0.01), and paleness was often reported by witnesses as opposed to vasovagal syncope (91% vs. 31%, p = 0.04). The rate of occurrence of palpitation and nausea in the prodromal phase was identical in both types of syncope. CONCLUSION: There exists a significant difference in anamnestic data of patients with cardiogenic syncope and those with vasovagal syncope. Derailed clinical history is a useful method in differential diagnosis of syncope.

Adult↗
PubMed2005

Inferring candidate genes for attention deficit hyperactivity disorder (ADHD) assessed by the World Health Organization Adult ADHD Self-Report Scale (ASRS).

The present study tests the psychometric properties and validity of the German version of the World Health Organization Adult Attention Deficit Hyperactivity Disorder (ADHD) Self-Report Scale (ASRS), which is a short screening instrument for use in the general population. Furthermore, two candidate genes for ADHD, the COMT VAL158MET and the 5-HT2a T102C polymorphisms, were tested for associations with the ASRS subscales inattention and hyperactivity/impulsivity in N = 203 healthy subjects. The ordinal CFA yielded a two-factorial model corroborating the structure of the official English WHO version. Genetic analysis revealed an association between the VAL allele of COMT and the inattention scale (F(1, 201) = 7.20, p = 0.008), the hyperactivity/impulsivity scale (F(1, 201) = 4.30, p = 0.039), and the total ASRS scale (F(2, 201) = 7.64, p = 0.006) with highest scores in carriers of the MET/MET genotype. The C-allele of 5-HT2a was significantly associated with the hyperactivity/impulsivity scale (F(1, 201) = 5.52, p = 0.020) and the total ASRS scale (F(1, 201) = 4.21, p = 0.042) with highest scores in carriers of the TT genotype. The data provide evidence for the structural as well as for the external validity of the ASRS.

Attention Deficit Disorder with Hyperactivity↗
PubMed2005

Differential activation of pre-SMA and SMA proper during action observation: effects of instructions.

Many neurophysiological studies give evidence for a matching system between action observation and imitation. We used functional MRI to investigate the effects of different instructions for observing identical stimuli of whole-body gymnastics movements. The imitative-like observation mode asked normal human participants to observe the sequence containing repetitive parts and to subsequently imagine the observed movements in the first-person perspective. The evaluative observation mode asked the participants to carefully observe and judge movement accuracy and consistency in the repetitive sequence. We hypothesized that the supplementary motor area would be specifically involved in performing the observational tasks. Results indicate that the SMA proper is generally activated during observation of whole-body gymnastic movements and shows pronounced activation in imitative-like observation mode. Pre-SMA activity can be differentially modulated by instructions related to the observation task.

Adult↗
PubMed2004

Personality and emotion: test of Gray's personality theory by means of an fMRI study.

Although it is known that there are fundamental personality differences in the behavioral responses to emotional stimuli, traits have scarcely been investigated in this context by means of functional imaging studies. To maximize the variance with respect to personality, the authors tested 12 control subjects and 12 subjects who had sadomasochistic experiences with respect to the relationship between J. A. Gray's (1970) personality dimensions, the behavioral approach system (BAS) and the behavioral inhibition system (BIS), and brain activity in regions of interest. The BIS was associated with activity in numerous brain areas in response to fear, disgust, and erotic visual stimuli, whereas few associations could he detected between the BAS and brain activity in response to disgust and erotic stimuli.

Adult↗
PubMed2002

The insula is not specifically involved in disgust processing: an fMRI study.

fMRI studies have shown that the perception of facial disgust expressions specifically activates the insula. The present fMRI study investigated whether this structure is also involved in the processing of visual stimuli depicting non-mimic disgust elicitors compared to fear-inducing and neutral scenes. Twelve female subjects were scanned while viewing alternating blocks of 40 disgust-inducing, 40 fear-inducing and 40 affectively neutral pictures, shown for 1.5 s each. Afterwards, affective ratings were assessed. The disgust pictures, rated as highly repulsive, induced activation in the insula, the amygdala, the orbitofrontal and occipito-temporal cortex. Since during the fear condition the insula was also involved, our findings do not fit the idea of the insula as a specific disgust processor.

Adult↗
PubMed2002

Latent inhibition and schizophrenia: Pavlovian conditioning of autonomic responses.

Latent inhibition (LI) is an important model for understanding cognitive deficits in schizophrenia. Disruption of LI is thought to result from an inability to ignore irrelevant stimuli. The study investigated LI in schizophrenic patients by using Pavlovian conditioning of electrodermal responses in a complete within-subject design. Thirty-two schizophrenic patients (16 acute, unmedicated and 16 medicated patients) and 16 healthy control subjects (matched with respect to age and gender) participated in the study. The experiment consisted of two stages: preexposure and conditioning. During preexposure two visual stimuli were presented. one of which served as the to-be-conditioned stimulus (CSp + ) and the other one was the not-to-be-conditioned stimulus (CSp - ) during the following conditioning ( = acquisition). During acquisition, two novel visual stimuli(CSn + and CSn - ) were introduced. A reaction time task was used as the unconditioned stimulus (US). LI was defined as the difference in response differentiation observed between preexposed and non-preexposed sets of CS + and CS - . During preexposure, the schizophrenic patients did not differ in electrodermal responding from the control subjects, neither concerning the extent of orienting nor the course of habituation. The exposure to novel stimuli at the beginning of the acquisition elicited reduced orienting responses in unmedicated patients compared to medicated patients and control subjects. LI was observed in medicated schizophrenic patients and healthy controls, but not in acute unmedicated patients. Furthermore LI was found to be correlated with the duration of illness: it was attenuated in patients who had suffered their first psychotic episode.

Adolescent↗
PubMed2001

Nematic liquid crystals with a tetrafluoroethylene bridge in the mesogenic core structure.

A dramatic increase of the clearing temperatures of liquid crystals based on bis(cyclohexyl)ethane 1 by 50 to 70 K can be achieved by the perfluorination of the central ethylene link. Conformational analysis indicates that this effect is due to the increased rigidity of the mesogenic core structure and to the suppression of conformers with a bent shape. Materials based on bis(cylohexyl)tetrafluoroethane 2 might play a crucial role as materials for the next generation of active matrix LCDs with reduced power consumption.

Journal Article↗
PubMed2001

Patterns of recovery of autonomic dysfunctions and neurocognitive deficits in schizophrenics after acute psychotic episodes.

In this study, the authors aimed to identify patterns of autonomic dysfunction and neurocognitive deficit recovery. The authors performed laboratory assessments on 66 patients with schizophrenia immediately after an acute psychotic episode and 6, 12, and 18 months later. Shortly after the psychotic episode, the patients displayed cardiovascular hyperarousal at rest, cardiovascular and electrodermal hyporeactivity during 2 Continuous Performance Tasks (CPTs) and deficits in 2 behavioral CPT measures (i.e., reaction time and omission error rate) compared with 29 normal controls. In the subsequent postpsychotic course, changes indicative of a process of recovery occurred in all measurement areas, although with regard to autonomic hyporeactivity amelioration was limited to a subgroup of schizophrenics with complete and persistent symptomatic remission. Neurocognitive improvement in CPTs did not appear to depend on unimpaired autonomic reactivity mechanisms.

Acute Disease↗
PubMed2000

The dimensional complexity of the EEG during cognitive tasks reflects the impaired information processing in schizophrenic patients.

The aim of the present study was to investigate whether schizophrenic patients show a different change of the dimensional complexity of the EEG, as represented by the Grassberger-Procaccia correlation dimension D(2,) under cognitive challenge compared to normal control subjects. With respect to results reported in the literature, it was expected that the complexity of the signal under cognitive challenge is higher in schizophrenic patients than in normal control subjects reflecting the impaired information processing abilities of the patients. Eighty-seven schizophrenic and 30 matched control subjects performed two different types of the continuous performance task. The results revealed differences between schizophrenic patients and control subjects for the performance as well as the complexity measures. Schizophrenic patients produced more omission errors than normal subjects did. For the EEG complexity measure no differences occurred under the baseline condition. In contrast, during the first minute under task conditions the control subjects showed a decrease of the dimension while no changes were found for the schizophrenic group. These results occurred for both types of the cognitive task but they reached clear significance only in one of them. The results are interpreted as reflecting the ability of normal subjects to adapt their information processing system to the cognitive challenge and to focus their attention on the task while schizophrenic subjects do not show this adaptation to the task.

Adult↗
PubMed1999

[Feelings without speech or speech without feelings? Further evidence for the decoupling hypothesis of alexithymia].

The theoretical background of the present investigation was the decoupling hypothesis of alexithymia, which presumes for alexithymic individuals a dissociation of psychophysiological indicators of emotion from verbal cognitive awareness of one's emotional state. To study alterations in reactivity to emotionally distressing stimuli in alexithymic individuals, 12 high-alexithymic and 14 low-alexithymic subjects (separated by TAS) out of a general sample of 54 were investigated. All subjects were exposed to cognitive (CPT) and affect inductive (film sequences) distress. During stimulus exposition electrodermal activity (spontaneous fluctuations) was recorded. After stimulus exposition the subjects assessed their emotional reaction towards the film sequences (DAS). Concerning electrodermal activity no differences were found between high and low alexithymics under cognitive distress. In any case a significant autonomous arousal was registered. However, only the low alexithymic subjects but not the high alexithymics showed a significant increase of spontaneous fluctuations as expression of autonomous arousal during presentation of affect inductive stimuli. The altered psychophysiological reactivity found in high alexithymics in contrast to low alexithymic subjects was revealed specifically for the processing of emotional qualified stimuli. However, there was no difference between the groups in cognitive self assessment of emotional response towards the film sequences. The findings are discussed with reference to neurophysiological and psychodynamic models and the decoupling hypothesis of alexithymia.

Adult↗
PubMed1999

Construction of spectral sensitivity function using polychromatic UV sources.

A procedure is presented for constructing the spectral sensitivity functions of biological dosimeters, using five polychromatic UV sources possessing different emission spectra. Phage T7 and uracil biological dosimeters have been used for measuring the dose rates of the lamps. Their spectral sensitivity functions consisting of two exponential terms have been constructed. The parameters of the spectral sensitivity functions have been determined by comparing the directly measured and calculated dose-rate values. The parameters of the sensitivity function are accepted as correct values when the deviation of the measured and calculated values is a minimum. Based on the deviations between the constructed and the experimentally determined spectral sensitivities with monochromatic sources, the differences between the measured and calculated results are interpreted. The importance of the correct spectral sensitivity data is demonstrated through the effectiveness spectra of a TL 01 lamp for phage T7 killing, uracil dimerization and erythema induction.

Bacteriophage T7↗
PubMed1996

Inhibition of human glutathione reductase by 10-arylisoalloxazines: crystalline, kinetic, and electrochemical studies.

A series of newly synthesized N(10)-arylisoalloxazines--some of which are known to be antimalarial agents--were studied as inhibitors of human glutathione reductase (GR;NADPH + GSSG + H(+) <==> NADP(+) + 2GSH). The flavoenzyme was inhibited with IC(50) values between </- 1 and 100 microM in the presence of 100 microM NADPH. The isoalloxazines and N(3)-methylisoalloxazines with a 4'-chlorophenyl or a 3',5'-dichlorophenyl group at N10 were found to be the most promising inhibitors of GR, although even the bulkier 10-naphthyl and -anthryl derivatives were also effective inhibitors. In contrast, at position N3 of the isoalloxazine ring, the size of the substituent was found to strongly influence the inhibitory effect. Introduction of a carboxymethyl group at N3--which markedly increased the solubility of the derivative in aqueous solutions-- caused a rise in the IC(50) values by 1 order of magnitude. 8-Fluoro- and 8-azido-10-arylisoalloxazines were potent inhibitors of GR; consequently position C8 of the benzenoid subnucleus instead of N3 should be considered for introducing substituents. No correlation was observed between the inhibitory strength of several isoalloxazines and their redox potential as measured by cyclovoltammetry. The crystallographic analysis of GR complexed with 10-(4'-chlorophenyl)-3-(carboxymethyl)isoalloxazine and 10-(3',5'-dichlorophenyl)-3-(carboxymethyl)isoalloxazine, respectively, revealed the presence of one inhibitor molecule bound at the 2-fold axis of the homodimeric protein. This location is consistent with fluorescence titration measurements and enzyme kinetic studies in solution which gave no indication for binding at the substrate sites.

Antimalarials↗
PubMed1995

Synthesis of N-acetylglucosaminyl asparagine-substituted puromycin analogues.

As part of our project aimed to introduce specifically glycosylated amino acids into proteins, new glycosylated puromycin analogues were chemically synthesized. Introduction of a free N-acetylglucosaminyl asparaginyl side chain abolished the activity of puromycin completely, but when the sugar OH groups were rendered increasingly hydrophobic by acetylation or benzylation, up to 8% of the activity was recovered. The results of our preliminary inhibition tests suggest that the interaction of puromycin analogues and therefore also of glycosylated aminoacyl tRNA, with the ribosomal A site increase with hydrophobicity of the modifying protecting groups.

Acetylglucosamine↗
PubMed1995

Autonomic indicators of information processing related to conditioning.

The aim of the present study was to quantitatively investigate the role of information processing in conditioning using stimuli with varying amounts of information content. A letter reproduction task varying in complexity served as the unconditioned stimulus. In the first experiment, we tested the indicator function of electrodermal and cardiovascular variables. The amount of information processing resources required emerged most clearly in electrodermal reactions (EDRs), showing an increase with increasing stimulus information content. A second experiment was performed using the same design to confirm the role of processing resources allocation during conditioning by means of an independent indicator. A reaction time task was introduced as a measure of information processing resources utilized. The results paralleled the dependence of EDRs on stimulus information content, as was found in the first experiment.

Adult↗
PubMed1991

Transdermal monotherapy with mepindolol BIO TSD in patients with stable angina pectoris. Placebo-controlled, crossover investigation of a new therapeutic concept with 12-hours overnight application.

10 patients (6 females and 4 males with an average age of 75 years) with stable angina pectoris were treated transdermally with mepindolol in a balanced, randomized, controlled, crossover study to compare the anti-ischemic effects of 12-hour overnight, and 24-hour applications. The number of angina pectoris attacks, the oral nitrate consumption and the ischemic parameters in 24-hour ECG, i.e. episodes of manifest (MMI) and silent (SMI) myocardial ischemia, the total duration of ischemia and 24-hour heart rate profiles were investigated. Both application schemes showed typical systemic beta blocker effects in all patients and significant clinical efficacy. A dose/effect relationship and a time/effect relationship between the two different application schemes were demonstrated across all the parameters investigated. Systemic and local tolerance of the therapy was good. 2 patients showed transient, mild skin irritation, but only during one phase of the study. Premature discontinuation was not necessary in any cases. There were no relevant changes in the clinical-chemistry. The new therapeutic concept of 24-hour treatment for a. pectoris with 12-hour overnight transdermal applications showed both good clinical efficacy and a good safety profile.

Administration, Cutaneous↗