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Biomedical subjects

R Kaiser

Publications and source records attributed to R Kaiser.

At least 19 recordsLinked to original sources
PubMed2003

L -dopa-induced adverse effects in PD and dopamine transporter gene polymorphism.

OBJECTIVE: To assess whether polymorphisms in the dopamine receptor genes and in the dopamine transporter gene (DAT ) are predictors of adverse effects of L -dopa. METHODS: A retrospective noninterventional study with 183 patients with PD was conducted. Nine polymorphisms of the dopamine D2 receptor (DRD2 ), two of the dopamine D3 receptor (DRD3 ), three of the dopamine D4 receptor (DRD4 ), and one variable number of tandem repeats (VNTR) of the DAT were studied. The entire coding and promoter regions of the DRD2 gene of 48 patients with early and severe appearance of adverse effects from L -dopa treatment and of eight never-afflicted patients were sequenced. RESULTS: The polymorphisms of DRD2, DRD3, and DRD4 were not associated with the risk to develop adverse effects of L -dopa. However, patients with psychosis or dyskinesia carried the nine copy allele 40-bp VNTR of the DAT more frequently than nonafflicted patients (60.0 vs 36.8%, p = 0.008; and 54.7 vs 32.9%, p = 0.006). Sequencing of the DRD2 gene revealed no new mutation, with the exception of one silent mutation in exon 6. CONCLUSIONS: Genetic variations of the DRD2, DRD3, and DRD4 do not influence the occurrence of L -dopa-induced adverse effects. However, the nine copy allele 40-bp VNTR of the DAT is a predictor for the occurrence of psychosis or dyskinesia in L -dopa-treated patients.

Aged↗
PubMed2003

Evidence for quark-hadron duality in the proton spin asymmetry A1.

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were scattered off a longitudinally polarized hydrogen target for values of Q2 between 1.2 and 12 GeV2 and values of W2 between 1 and 4 GeV2. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable x. This finding implies that the description of A1 in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of Q2 above 1.6 GeV2.

Journal Article↗
PubMed2003

Q2 dependence of nuclear transparency for exclusive rho0 production.

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.

Journal Article↗
PubMed2003

Selective modulation of endogenous nitric oxide formation in ischemia/reperfusion injury in isolated rat hearts--effects on regional myocardial flow and enzyme release.

The role of nitric oxide (NO) in ischemia/reperfusion injury is controversial. We tested the role of inducible NOS (iNOS) in the ischemia/reperfusion injury in isolated rat hearts using the selective iNOS inhibitor S-methylisothiourea sulfate (SMT) and the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). After 15 min of stabilization in Langendorff mode, hearts were perfused either with normal Krebs-Henseleit buffer, buffer containing 100 microM L-NAME, 0.5 microM SMT or 50 microM SMT for 5 min and were subjected to 25 min of ischemia followed by 30 min of reperfusion. Left ventricular developed pressure (LVDP) and total coronary flow (CF) were recorded continuously. After ischemia/reperfusion, a marked expression of iNOS protein was demonstrated by Western blotting, while virtually no iNOS protein was present in hearts without ischemia/reperfusion. Regional myocardial blood flow (RMBF) was measured with colored microspheres. Coronary vasoactive concentration of L-NAME and SMT depressed myocardial function as shown by decreased LVDP, dP/dt(max) and coronary.ow before ischemia. After ischemia the recovery of the total CF was impaired in L-NAME and 50 microM SMT pretreated hearts which was related to homogenous RMBF decrease in the right and left ventricle compared to that in control group. Low concentration SMT (0.5 microM) showed no coronary vasoactive effects before ischemia and attenuated ischemia/reperfusion injury indicated by lower ischemic contracture at 25 min of ischemia and reduced CK and LDH release during reperfusion. Thus, NOS inhibition did not affect blood flow distribution in rat hearts either in the pre-ischemic or reperfusion period. Selective iNOS inhibition reduced ischemic injury by reducing ischemic contracture and CK as well as LDH release during reperfusion.

Animals↗
PubMed2003

[Importance of the Therapeutic Products Act for the ENT practitioner].

The Therapeutic Products Act controls therapeutic products and their fields of application, and classifies them legally. The present regulations on therapeutic products are based on a fundamental concept comprising basic demands, harmonized standards, agreement of the product attributes with the basic demands, and assessment of conformity. Therapeutic products (among which in vitro diagnostics are counted) must comply with definite regulations and are separated from medicines by their mode of action. In addition, therapeutic products must be subject to critical testing. The establishment, management, and use of therapeutic products are, with few exceptions, governed by the Regulations for the Use of Therapeutic Products. To avoid possible risks involved in the application of therapeutic products, a well-functioning system of registration is required, controlled by the Regulations on Therapeutic Products Safety.

Device Approval↗
PubMed2002

Hanle effect in coherent backscattering.

We study the shape of the coherent-backscattering (CBS) cone obtained when resonant light illuminates a thick cloud of laser-cooled rubidium atoms in the presence of a homogenous magnetic field. We observe new magnetic field-dependent anisotropies in the CBS signal. We show that the observed behavior is due to the modification of the atomic-radiation pattern by the magnetic field (Hanle effect in the excited state).

Journal Article↗
PubMed2002

[Stroke management on general medical departments. A multicenter study in Austria].

BACKGROUND AND OBJECTIVE: Despite the claimed superiority of Stroke Units a majority of patients with acute stroke is still treated on general medical departments in many countries. In Austria 90 % of 121 medical departments state that they take care of stroke patients routinely or at least sometimes. Therefore, our aim was to evaluate whether stroke management on medical wards meets up-to-date standards. PATIENTS AND METHODS: 55 medical departments all over Austria participated in a prospective multicenter registry documenting diagnostics, treatment and the in-hospital course of unselected patients admitted with an acute stroke according to a standardised protocol. RESULTS: 1100 patients, 56 % female, with a median age of 75 years were assessed. Median hospital stay was 14 days. In 96 % a cranial computer tomogram was performed. 81 % of cerebral lesions were ischemic, 10 % haemorrhagic. Only 10 % had no risk factor or accompanying medical disease. 31 % suffered at least one medical and 18 % one neurological complication (p = 0.00000003). In-hospital mortality was 17 %, functional outcome was poor in 27 % (Rankin scale [RS] 4 or 5) and good in 56 % (RS 0-3). 74 % of discharged patients could leave to their home, 13 % were transferred to a nursing home and 13 % to a rehabilitation center. 95 % of surviving patients left on either an antiplatelet or an anticoagulant medication and 73 % received antihypertensives. CONCLUSION: Outcome of stroke patients treated on general medical departments seems to be fairly comparable to that commonly reported by neurological Stroke Units. Further improvements may be obtained by implementation of integrated "mixed assessment" units into medical departments.

Aged↗
PubMed2002

Coherent light transport in a cold strontium cloud.

We study light coherent transport in the weak localization regime using magneto-optically cooled strontium atoms. The coherent backscattering cone is measured in the four polarization channels using light resonant with a J(g) = 0-->J(e) = 1 transition of the strontium atom. We find an enhancement factor close to 2 in the helicity preserving channel, in agreement with theoretical predictions. This observation confirms the effect of internal structure as the key mechanism for the contrast reduction observed with a rubidium cold cloud [G. Labeyrie et al., Phys. Rev. Lett. 83, 5266 (1999)]. Experimental results are in good agreement with Monte Carlo simulations taking into account geometry effects.

Journal Article↗
PubMed2002

Relationship between adverse effects of antipsychotic treatment and dopamine D(2) receptor polymorphisms in patients with schizophrenia.

Extrapyramidal adverse symptoms (EPS) represent a major type of adverse events in treatment with typical antipsychotic drugs which share high affinity to the dopamine D(2) receptor (DRD2). Genetic variants of this receptor may modulate the therapeutic response and the severity of adverse symptoms of antipsychotics. We analyzed nine known polymorphisms of the DRD2 in 665 schizophrenic patients with European Caucasian ethnic background and compared the intensity of acute dystonia, extrapyramidal symptoms, akathisia, and tardive dyskinesia between carriers of different DRD2 genotypes. In a subgroup of 40 patients with most severe extrapyramidal symptoms we sequenced the coding region including the exon-intron junctions of the DRD2 gene. Functionally relevant DRD2 amino acid variants (Ser(310), Cys(311)) were rare or were not found at all (Ala(96)). Complete sequence analysis of sufferers from the most severe adverse effects revealed two new intronic polymorphisms and a silent polymorphism in exon 7, but no new amino acid variants beyond those which are already known. We found no significant association between these polymorphisms and the intensity of the different types of adverse neurologic effects of the antipsychotics. These results were obtained by correlating adverse events with each of the nine single nucleotide polymorphisms and by correlation with the estimated haplotypes. In conclusion, genetic variations in the DRD2 gene were no major predictors of the individually variable adverse effects from antipsychotic treatment in Caucasian schizophrenic patients.

Adolescent↗
PubMed2001

Chaos-assisted tunneling with cold atoms.

In the context of quantum chaos, both theory and numerical analysis predict large fluctuations of the tunneling transition probabilities when irregular dynamics is present at the classical level. Here we consider the nondissipative quantum evolution of cold atoms trapped in a time-dependent modulated periodic potential generated by two laser beams. We give some precise guidelines for the observation of chaos-assisted tunneling between invariant phase space structures paired by time-reversal symmetry.

Journal Article↗
PubMed2001

Assessment of deaths attributable to air pollution: should we use risk estimates based on time series or on cohort studies?

Epidemiologic studies are crucial to the estimation of numbers of deaths attributable to air pollution. In this paper, the authors present a framework for distinguishing estimates of attributable cases based on time-series studies from those based on cohort studies, the latter being 5-10 times larger. The authors distinguish four categories of death associated with air pollution: A) air pollution increases both the risk of underlying diseases leading to frailty and the short term risk of death among the frail; B) air pollution increases the risk of chronic diseases leading to frailty but is unrelated to timing of death; C) air pollution is unrelated to risk of chronic diseases but short term exposure increases mortality among persons who are frail; and D) neither underlying chronic disease nor the event of death is related to air pollution exposure. Time-series approaches capture deaths from categories A and C, whereas cohort studies assess cases from categories A, B, and C. In addition, years of life lost can only be derived from cohort studies, where time to death is the outcome, while in time-series studies, death is a once-only event (no dimension in time). The authors conclude that time-series analyses underestimate cases of death attributable to air pollution and that assessment of the impact of air pollution on mortality should be based on cohort studies.

Air Pollutants↗
PubMed2001

Invisible mean field dynamos.

We provide examples of alpha(2) dynamos in spheres which generate magnetic fields that are confined to the conductor and are therefore undetectable in the surrounding vacuum.

Journal Article↗
PubMed2001

Paraneoplastic polyneuropathy preceding the diagnosis of Hodgkin's disease and non-small cell lung cancer in a patient with concomitant Borrelia burgdorferi infection.

A patient with painful peripheral neuropathy is presented, whose symptoms were thought to result from an infection with Borrelia burgdorferi sensu lato. Investigations of the cerebrospinal fluid for signs of inflammation and borrelial antibodies were negative, and the patient did not benefit from repeated antibiotic treatment. Electrophysiologic studies and sural nerve biopsy showed axonal neuropathy consistent with a paraneoplastic syndrome. Further workup revealed mediastinal Hodgkin's disease (HD; nodular sclerosing subtype) Ann Arbor stage II and non-small cell cancer of the lung (stage T1N0M0). Surgical resection of the lung cancer and combined chemo- and radiotherapy for HD resulted in complete remission of both malignancies. While the preexisting neurologic symptoms persisted during treatment, neurography showed some improvement of the distal nerves. During radiation therapy the patient developed transient left-sided brachial plexopathy. This case illustrates that the diagnosis of borreliosis in patients with isolated painful peripheral neuritis cannot be based solely upon positive IgG titers and supports the requirement for a thorough workup for an underlying--potentially curable--disease. In addition, singular pulmonary lesions in the setting of HD should be suspected to have a separate cause.

Adult↗
PubMed2001

Differences in substance abuse patterns: multiple drug abuse alone versus schizophrenia with multiple drug abuse.

OBJECTIVE: To compare the lifetime consumption patterns of patients with schizophrenia and multiple substance abuse and multiple substance abusers without schizophrenia. METHOD: Two hundred and thirty in-patients of a specialized rehabilitation facility for young drug abusers were assessed with regard to their lifetime consumption patterns of 16 different classes of psychoactive drugs. While 110 patients had no diagnosis of a schizophrenic disorder, 120 patients had a comorbidity of multiple substance abuse and schizophrenia. RESULTS: Comorbid patients reported a higher lifetime consumption of hallucinogens, whereas multiple substance abusers without schizophrenia showed a higher lifetime consumption rate of cocaine. CONCLUSION: The differences found in lifetime consumption patterns between comorbid patients and substance abusers without psychotic disorder do not support the so-called self-medication hypothesis. Instead, the differences in lifetime consumption of certain drugs might be a result of lower social competence and standing in schizophrenic patients and lower ability to procure certain illicit drugs.

Adult↗
PubMed2001

Serotonin transporter polymorphisms: no association with response to antipsychotic treatment, but associations with the schizoparanoid and residual subtypes of schizophrenia.

The human serotonin transporter gene (5-HTT) demonstrates two polymorphisms with possible functional impact: a 44-bp insertion/deletion polymorphism of the promoter region and a 17-bp variable number of tandem repeat polymorphism (VNTR) in intron 2 (STin2). Such genetic polymorphisms in the serotoninergic system may increase the susceptibility to schizophrenia or may serve as predictors of therapeutic response. We therefore analyzed these polymorphisms as susceptibility factors for schizophrenia by comparison of 684 schizophrenic inpatients with 587 healthy controls. We furthermore compared the therapeutic outcome of schizophrenic patients differentiated by the 5-HTT genotypes. Schizo-affective patients were more frequently homozygous for the 44-bp insertion allele (Odds ratio, OR: 1.6, 95% confidence interval, CI: 1.1--2.3, P < 0.03) than were all other schizophrenic patients and controls. The 17-bp VNTR alleles found were: STin2.7, 9, 10, and 12. Sequence analysis revealed seven different sequence motifs with an invariable arrangement. Patients with schizo-paranoid schizophrenia were more frequently homozygous for the STin2.12 allele than were controls (OR: 1.4, CI: 1.1--1.8, P < 0.007) and all other schizophrenic patients (OR: 1.6, CI: 1.2--2.3). The STin2.9 allele represented a risk factor for the residual subtype of schizophrenia (OR: 6.4, CI: 2.5--16.2, P < 0.001). On the basis of global clinical impressions, as well as measurements with the positive and negative syndrome scale we found no association of the polymorphisms with therapeutic response. In conclusion, the 44-bp polymorphism may be associated with the schizo-affective and the 17-bp VNTR with the residual and schizo-paranoid subtype of schizophrenia, findings which require further biochemical and epidemiological confirmation.

Adolescent↗