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Biomedical subjects

F Seifert

Publications and source records attributed to F Seifert.

At least 19 recordsLinked to original sources
PubMed2006

Association between cerebral glutamate and human behaviour: the sensation seeking personality trait.

INTRODUCTION: Brain imaging studies have linked the anterior cingulate cortex (ACC) to motivation, drive, and personality traits like novelty and sensation seeking. Animal studies have shown glutamatergic neurotransmission to be important in ACC function as well as motivated behaviour. However, the role of glutamate in related personality traits like sensation seeking has not been investigated in humans. METHODS: The associations between sensation seeking personality scores and absolute glutamate concentrations in the ACC and the hippocampal region measured by 3-Tesla proton magnetic resonance spectroscopy (1H-MRS) were investigated. RESULTS: ACC glutamate concentration was negatively correlated with the sensation seeking sum score and the experience seeking subscore. A weak negative correlation was also observed between the hippocampal glutamate and the sensation seeking sum score. The reexamination of the glutamate concentration after 4 weeks revealed a similar relationship with sensation seeking. DISCUSSION: Although preliminary, the results are in line with the key role of the ACC for motivation and executive control and with the impact of glutamate on novelty related behaviour observed in animal experiments. The role of the hippocampus for novelty processing is discussed. Glutamate measurement with 1H-MRS may facilitate the understanding of biological underpinnings of personality traits and psychiatric diseases associated with dysfunctions in motivation and drive.

Adult↗
PubMed2006

Hippocampal glutamate concentration predicts cerebral theta oscillations during cognitive processing.

RATIONALE: Brain waves reflect collective behavior of neurons and provide insight into distributed network processing. Frontal and hippocampal theta oscillations (4-7 Hz) were linked to cognitive tasks and animal studies have suggested an involvement of glutamatergic neurotransmission in integrative frontal-hippocampal processing. Human evidence for such relationships is lacking. METHODS: Here, we studied the associations between glutamate concentrations in the hippocampal region, measured by a 3-T proton magnetic resonance spectroscopy (1H-MRS), and EEG theta activity during an auditory target detection paradigm. RESULTS: A robust relationship between hippocampal glutamate and frontal theta activity during stimulus processing was found. Moreover, frontal theta oscillations were related to response speed. CONCLUSION: The results suggest a functional coupling between the frontal cortex and hippocampal region during stimulus processing and support the idea of the hippocampus as a neural rhythm generator driven by glutamatergic neurotransmission. These preliminary data show, for the first time, a relationship between in vivo measured glutamate and basic cerebral information processing in humans.

Adult↗
PubMed2006

[Retropharyngeal tendinitis. Differential diagnosis in the management of acute neck pain].

Neck pain is frequent and can be a symptom of numerous differential diagnoses with quite different diagnostic and therapeutic consequences. A 37-year-old woman reported acute neck pain aggravated by movements of the cervical spine and head and by swallowing. Clinical examination showed pronounced neck stiffness. T2-weighted MRI demonstrated high-intensity edema and effusion localized prevertebrally in the area of the superior part of the longus colli muscle. Computed tomography of this region demonstrated prevertebral calcification leading to the diagnosis of retropharyngeal tendinitis. Nonsteroidal antiphlogistic drugs led to rapid improvement of clinical signs and symptoms. Retropharyngeal tendinitis should be considered in patients with acute neck pain.

Acute Disease↗
PubMed2003

Injection pain of rocuronium and vecuronium is evoked by direct activation of nociceptive nerve endings.

BACKGROUND AND OBJECTIVE: Rocuronium and, to a lesser extent, vecuronium can induce burning sensations associated with withdrawal reactions during administration. Dermal microdialysis in human and electrophysiological recordings of nociceptors in mouse skin were used to elucidate the underlying mechanisms of pain induction. METHODS: Microdialysis catheters were inserted intradermally into the forearm of 10 volunteers and were perfused with two different concentrations of rocuronium and vecuronium (1 and 10 mg mL(-1)) or a control. Dialysis samples were taken every 15 min and analysed for protein, histamine, tryptase and bradykinin content. Pain intensity was rated on a numerical scale of 0-10. In a parallel design, activation of cutaneous nociceptors was assessed directly in a skin-nerve in vitro preparation of the mouse hind paw. The receptive fields of identified single C-nociceptors (n = 12) were superfused with rocuronium or vecuronium solutions (10 mg mL(-1)) at physiological pH. RESULTS: In accordance with clinical observations, microdialysis of rocuronium (10 mg mL(-1)) induced sharp burning pain (NRS 4.1 +/- 1.8), whereas vecuronium given in the usual clinical concentration (1 mg mL(-1)) induced only minor pain sensations (NRS 0.6 +/- 1.3). At equimolar concentrations, pain sensation and concomitant mediator release evoked by both drugs were similar. No correlations were found between pain rating and mediator release. In the in vitro preparation, C-fibres showed a consistent excitatory response with rapid onset after stimulation with vecuronium as well as rocuronium (differences not significant). CONCLUSIONS: The algogenic effect of aminosteroidal neuromuscular blocking drugs can be attributed to a direct activation of C-nociceptors.

Adult↗
PubMed2001

Symmetry role on the preedge X-ray absorption fine structure at the metal K edge.

The preedge features in a system with "even" symmetry, apart from quadrupolar transition contribution, are mainly dipolar in character, associated with the existence of unoccupied states made up of mixed cation-4p with higher-neighboring cation-3d orbitals, and reflect the density of states due to the medium-range order of the system. In "odd" symmetry materials these preedge features are the result of a transition from the 1s to a final density of states of p symmetry due to an unsymmetrical mixing of the ligand wave functions with the central cation 3d orbitals, similar to atetrahedral configuration. These results are validated for Fe as a photoabsorber by comparing XAS spectra of Fe2SiO4 (fayalite) to ab initio full multiple scattering calculations at the Fe K edge, but pertain to all systems containing sixfold-coordinated cations.

Journal Article↗
PubMed2001

Oxygen 1s ELNES study of perovskites (Ca,Sr,Ba)TiO3.

The O K-edge spectra of perovskites XTiO3 with X=Ca, Sr and Ba have been measured using electron energy-loss spectroscopy (EELS) and are analyzed using the ab initio full multiple-scattering (MS) calculations. The near-edge structures arise mainly from covalency by direct and/or indirect interaction between oxygen and metal. The coordination number of the cation and the site symmetry also influence the spectral shape and structures. Comparison of full MS simulations of different clusters around the excited atom allows to interpret and correlate the features present in the spectra of each compound to its specific atomic arrangement and electronic structure.

Journal Article↗
PubMed2001

Experimental and theoretical XANES study of the effects of Fe-Mg solid solution in the enstatite-ferrosilite series.

Synthetic orthopyroxenes in the join enstatite - ferrosilite (Mg2Si2O6-Fe2Si2O6) have been studied by XANES with the aim to interpret the variations found in the spectra and evaluate the effects of the Mg-Fe substitution in the orthopyroxene (OPX) structure. The experimental Fe- and Mg-K edge XANES spectra show variations of the peaks intensity as a function of the chemical composition of the samples along the EN-FS join. In the region of the Fe edge, the intensity ratio between peak A and B (IB/IA) varies linearly (R=0.99) with the Mg/Fe substitution. Multiple scattering calculation have been performed both at the Fe and Mg K-edge, to study the geometrical modifications of the M1 and M2 octahedral sites induced by the Mg-Fe substitutions. The spectra, obtained locating Fe (or Mg) in both M1 and M2 and weighing the contributions using the occupancy data for the M1 and M2 sites determined by XRD, allow to discriminate the effects to the total spectrum due to Fe (Mg) located in each sites separately.

Journal Article↗
PubMed2001

[Therapy of active Crohn disease with Boswellia serrata extract H 15].

BACKGROUND: The purpose of this clinical trial was to compare efficacy and safety of the Boswellia serrata extract H15 with mesalazine for the treatment of active Crohn's disease. PATIENTS AND METHODS: Randomised, double-blind, verum-controlled, parallel group comparison for which 102 Patients were randomised. The per protocol population included 44 patients treated with H15 and 39 patients treated with mesalazine. As primary outcome measure the change of the Crohn Disease Activity Index (CDAI) between the status of enrolment and end of therapy was chosen. H 15 was tested on non-inferiority compared to standard treatment with mesalazine. RESULTS: The CDAI between the status of enrolment and end of therapy after treatment with H15 was reduced by 90 and after therapy with mesalazine by 53 scores in the mean. In this non-inferiority-trial the test hypothesis was confirmed by the statistical analysis. The difference between both treatments could not be proven to be statistically significant in favor to H15 for the primary outcome measure. The secondary efficacy endpoints confirm the assessment of the comparison of H15 and mesalazine. The proven tolerability of H15 completes the results of the shown clinical efficacy. CONCLUSIONS: The study confirms that therapy with H15 is not inferior to mesalazine. This can be interpreted as evidence for the efficacy of H15 according to the state of art in the treatment of active Crohn's disease with Boswellia serrata extract, since the efficacy of mesalazine for this indication has been approved by the health authorities. Considering both safety and efficacy of Boswellia serrata extract H15 it appears to be superior over mesalazine in terms of a benefit-risk-evaluation.

Adult↗
PubMed2000

Evidence for negative cross correlations in vibrational dephasing in liquids: isotropic raman-line shift and width phenomena in isotopic mixtures of N2 and O2

To experimentally confirm the hypothesis of negative cross terms between different dephasing mechanisms, potentially leading to a broadening of the isotropic Raman line upon isotopic dilution, we present a detailed study on the concentration dependencies of all of the line shifts and widths in the four isotopic mixtures of type (15N14N)(x)-(14N2)(1-x), (15N2)(x)-(14N2)(1-x), (15N2)(x)-(15N14N)(1-x), and (16O2)(x)-(18O2)(1-x) near the normal boiling point of nitrogen at T = 77.35 K. A quite disparate behavior of the nitrogen oscillators compared to the oxygen oscillators was observed in respect to a change of their isotopic baths.

Journal Article↗
PubMed2000

Human cardiac imaging at 3 T using phased array coils.

Using a two-element phased array receiver coil, single breath-hold, ECG gated cardiac images of signal-to-noise ratios up to 130 and contrast-to-noise ratios exceeding 35 between myocardium and blood were recorded at 3 T. At several locations within the myocardium, T*(2) and B(0) inhomogeneity were determined. Because of shorter T*(2) times and larger B(0) inhomogeneities attributable to enhanced susceptibility effects, real-time cardiac imaging, the use of spiral scans, and echo planar imaging are expected to be considerably more difficult at 3 T.

Artifacts↗
PubMed2000

Quantitative MRS: comparison of time domain and time domain frequency domain methods using a novel test procedure.

For quantitative analysis of in vivo MR spectra, a state-of-the-art time domain method was compared with a recently reported time domain frequency domain method which uses wavelets for background characterization. The comparison was made on the basis of results for simulated test problems that were constructed by combining measured and simulated MRS data at different signal-to-noise ratios in order to simultaneously reflect real world difficulties, in particular the overlapping background problem, and to allow for quantitative judgment of a method's accuracy. Incorporating prior knowledge was also considered. The results obtained give insight into the accuracy of the methods when applied to measured MRS data. Due to the improved background characterization, the time domain frequency domain method outperformed the time domain method in some of the test cases. Both methods were also applied to serial brain MR spectra of a healthy volunteer on 10 occasions.

Brain↗
PubMed1996

Cell cycle effects of thaliblastine.

The non-myelotoxic antitumor drug thaliblastine (thalicarpine, NSC-68075, CAS-5373-42-21) has a novel chemical structure; it is a complex dimeric-type aporphine benzylisoquinoline alkaloid possessing antiproliferative and antitumor activities in experimental and clinical studies. In this study the effect of this drug on the cell cycle progression of ovarian tumor line O-342 and its cisplatin-resistant subline O-342/DDP was evaluated. As assessed by flow cytometric analysis, thaliblastine affected the cell cycle progression. In both lines, a comparable pattern of cell cycle arrest was found. Within the first 5 h of thaliblastine exposure, a G2/M block was observed; thereafter cell-cycle arrest in G1 became prominent, while S-phase cells finished DNA replication.

Animals↗
PubMed1995

Initial clinical experience with rectus sheath grafts in congenital heart defects.

This study reports on the initial clinical experience using anterior rectus sheath as potentially growing graft material in congenital heart lesions. The first seven patients with complex congenital lesions requiring a rectus sheath graft because of inadequate available pericardium are reviewed. The initial operations were: TOF (unicusp pulmonary valve) (re-op), two Konno procedures (one VSD and one RV patch), two arterial switch procedures for TGA (neoaortic augmentation), two Fontan (re-op) atrial augmentation patch and pulmonary arterioplasty (re-op). Ages ranged from 1 week to 15 years. Follow-up ranged from 1 to 72 months and included open visual inspection at reoperation in 5 cases, angiography in 3 cases, and echocardiography in 4 cases. One early respiratory death occurred in the fourth postoperative week. So far no early bleeding from rectus sheath patches, infection, aneurysmal dilatation, or scar contraction was observed. No manifestation of peripheral emboli was seen. Hernias of the harvest site were absent. We concluded that in absence of pericardium and in areas where future cicatrization or aneurysmal dilatation is undesirable, anterior rectus sheath appears to be a reasonable alternative.

Adolescent↗
PubMed1992

[Ibuprofen--successful in activated arthrosis. Results of a administration study].

Within the framework of an observational study carried out on a national basis and involving some 4,000 patients, a total of 1,156 patients with activated arthrosis were treated with oral ibuprofen and observed over a period of three weeks. It was found that, at a dose of 600 mg tid, ibuprofen led to significant remission rates in terms of the symptoms pain at rest, pain on movement, tenderness, restriction of movement, swelling, joint effusion, and morning stiffness. After the third week of treatment, these rates reached 90%. In the first week, rapid onset of action within the first 30 minutes was noted in about 50%, which increased in the third week to 65%. Since at the same time the tolerability of ibuprofen was also found to be good--4% side effects--it can be recommended also for long-term use in this indication.

Arthritis, Rheumatoid↗
PubMed1992

Antioxidants and Manganese Deficiency in Needles of Norway Spruce (Picea abies L.) Trees.

Chlorotic and green needles from Norway spruce (Picea abies L.) trees were sampled in the Calcareous Bavarian Alps in winter. The needles were used for analysis of the mineral and pigment contents, the levels of antioxidants (ascorbate, glutathione), and the activities of protective enzymes (superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate radical reductase, dehydroascorbate reductase, glutathione reductase). In addition, the activities of two respiratory enzymes (glucose-6-phosphate dehydrogenase, NAD-malate dehydrogenase), which might provide the NADPH necessary for functioning of the antioxidative system, were determined. We found that chlorotic needles were severely manganese deficient (3 to 6 micrograms Mn per gram dry weight as compared with up to 190 micrograms Mn per gram dry weight in green needles) but had a similar dry weight to fresh weight ratio, had a similar protein content, and showed no evidence for enhanced lipid peroxidation as compared with green needles. In chlorotic needles, the level of total ascorbate and the activities of superoxide dismutase, monodehydroascorbate radical reductase, NAD-malate dehydrogenase, and glucose-6-phosphate dehydrogenase were significantly increased, whereas the levels of ascorbate peroxidase, dehydroascorbate reductase, glutathione reductase, and glutathione were not affected. The ratio of ascorbate to dehydroascorbate was similar in both green and chlorotic needles. These results suggest that in spruce needles monodehydroascorbate radical reductase is the key enzyme involved in maintaining ascorbate in its reduced state. The reductant necessary for this process may have been supplied at the expense of photosynthate.

Journal Article↗