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Biomedical subjects

M Ruf

Publications and source records attributed to M Ruf.

At least 19 recordsLinked to original sources
PubMed2005

[One decade of functional imaging in schizophrenia research. From visualisation of basic information processing steps to molecular-genetic oriented imaging].

Modern neuroimaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET) have contributed tremendously to our current understanding of psychiatric disorders in the context of functional, biochemical and microstructural alterations of the brain. Since the mid-nineties, functional MRI has provided major insights into the neurobiological correlates of signs and symptoms in schizophrenia. The current paper reviews important fMRI studies of the past decade in the domains of motor, visual, auditory, attentional and working memory function. Special emphasis is given to new methodological approaches, such as the visualisation of medication effects and the functional characterisation of risk genes.

Biomarkers↗
PubMed2005

[Functional imaging of neurocognitive dysfunction in attention deficit hyperactivity disorder].

Attention Deficit Hyperactivity Disorder (ADHD) is a neurobiological disorder of early childhood onset. Defining symptoms are chronic impairments of attention, impulse control and motor hyperactivity that frequently persist until adulthood. Miscellaneous causes of the disorder have been discussed. Accumulating evidence from imaging- and molecular genetic studies strengthened the theory of ADHS being a predominantly inherited disorder of neurobiological origin. In the last 15 years, non-invasive brain imaging methods were successfully implemented in pediatric research. Functional magnetic resonance imaging studies gave major insight into the neurobiological correlates of executive malfunction, inhibitory deficits and psychomotoric soft signs. These findings are in good accordance with brain morphometric data indicating a significant volumetric decrease of major components of striato-thalamo-cortical feedback loops, primarily influencing prefrontal executive functioning (e.g. basal ganglia). Empirical evidence points to a broad array of associated behavioral disturbances like deficient visuomotor abilities and oculomotor dysfunctions. This paper reviews the current empirical evidence derived from prior imaging studies. Special emphasis is given to the relevance of oculomotor dysfunctions in clinical and research settings, as well as their assessment in the MR environment.

Attention Deficit and Disruptive Behavior Disorder↗
PubMed2005

Should a low prevalence of asymptomatic Chlamydia trachomatis infection in gay men attending HIV clinics discourage from opportunistic screening?

Genitourinary (GU) medicine notifications for homosexually acquired Chlamydia trachomatis (CT) infections show a 414% increase from 1996 to 2002. However, little is known about the prevalence of CT in men who have sex with men (MSM) outside GU medicine settings. Behavioural studies show that MSM with diagnosed HIV infection continue to engage in high-risk sexual behaviour with the risk for sexually transmitted infections (STI) acquisition and HIV transmission. This study analysed the results of urine-based CT screening in MSM attending a London HIV clinic in order to inform local policy on the benefit and patients' acceptability of opportunistic screening. Among men screened, 1.9% (2/107) had asymptomatic CT infection. Screening was well accepted and practical to be implemented in the clinic routine. It is unclear whether isolated routine urine screening is cost effective in the context of HIV prevention. HIV clinics should incorporate a public health perspective and actively contribute to HIV prevention by addressing sexual health and scope opportunities for STI screening.

AIDS-Related Opportunistic Infections↗
PubMed2004

Molecular markers reveal extensive intraspecific below-ground overlap of silver fir fine roots.

Fine roots are expected to be important determinants of plant competition, but very little is known about the extent of root system overlap. Here, we describe the application of two highly variable plastide microsatellites to study the fine root distribution of tree individuals in a silver fir forest. We demonstrate that the spread of fine roots exceeds the width of above-ground parts, and that fine root overlaps among neighbouring trees are extensive both laterally and in depth. This approach will help to improve models of below-ground competition and will facilitate estimations of fine root biomass and thus of below-ground C pools.

Abies↗
PubMed2001

Excision of uranium oxide chains and ribbons in the novel one-dimensional uranyl iodates K(2)[(UO(2))3(IO(3))(4)O(2)] and Ba[(UO(2)2(IO(3))(2)O(2)](H(2)O).

The alkali metal and alkaline-earth metal uranyl iodates K(2)[(UO(2))(3)(IO(3))(4)O(2)] and Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) have been prepared from the hydrothermal reactions of KCl or BaCl(2) with UO(3) and I(2)O(5) at 425 and 180 degrees C, respectively. While K(2)[(UO(2))(3)(IO(3))(4)O(2)] can be synthesized under both mild and supercritical conditions, the yield increases from <5% to 73% as the temperature is raised from 180 to 425 degrees C. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), however, has only been isolated from reactions performed in the mild temperature regime. Thermal measurements (DSC) indicate that K(2)[(UO(2))(3)(IO(3))(4)O(2)] is more stable than Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) and that both compounds decompose through thermal disproportionation at 579 and 575 degrees C, respectively. The difference in the thermal behavior of these compounds provides a basis for the divergence of their preparation temperatures. The structure of K(2)[(UO(2))(3)(IO(3))(4)O(2)] is composed of [(UO(2))(3)(IO(3))(4)O(2)](2)(-) chains built from the edge-sharing UO(7) pentagonal bipyramids and UO(6) octahedra. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) consists of one-dimensional [(UO(2))(2)(IO(3))(2)O(2)](2)(-) ribbons formed from the edge sharing of distorted UO(7) pentagonal bipyramids. In both compounds the iodate groups occur in both bridging and monodentate binding modes and further serve to terminate the edges of the uranium oxide chains. The K(+) or Ba(2+) cations separate the chains or ribbons in these compounds forming bonds with terminal oxygen atoms from the iodate ligands. Crystallographic data: K(2)[(UO(2))(3)(IO(3))(4)O(2)], triclinic, space group P_1, a = 7.0372(5) A, b = 7.7727(5) A, c = 8.9851(6) A, alpha = 93.386(1) degrees, beta = 105.668(1) degrees, gamma = 91.339(1) degrees, Z = 1; Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), monoclinic, space group P2(1)/c, a = 8.062(4) A, b = 6.940(3) A, c = 21.67(1), beta= 98.05(1) degrees, Z = 4.

Journal Article↗
PubMed2001

Alcohol-associated stimuli activate the ventral striatum in abstinent alcoholics.

Alcohol-associated cues may act as conditioned stimuli that activate the brain reward system and motivate alcohol intake in alcoholics. Alcohol-associated visual stimuli were presented during functional magnetic resonance imaging. An activation of the ventral putamen was observed in alcoholics but not in control subjects. Patients with a strong activation of the ventral putamen relapsed during the next three months. This observation supports the hypothesis that alcohol use affects areas involved in brain reward circuits and that their stimulus-induced activation may be associated with an increased risk for relapse.

Adult↗
PubMed2001

[Homosexual pedophilia and functional networks - An fMRI case report and literature review].

Pedophilia is a complex bio-psycho-social disorder often associated with serious offending. Knowledge about neurobiological correlates that could serve as diagnostic and maybe even as prognostic markers is limited. FMRI examination, which shows neuronal activation in vivo and therefore represents a neurobiological correlate, was not done in pedophilia so far. We report on results of an fMRI examination in a homosexual pedophilic sex offender who differed significantly in neuronal activation during exposure to arousing visual material (young boys in underwear) from normal controls. In self assessment on a visual analogous scale the pedophilic offender scored the pictures of the boys as not being interesting and sexually not stimulating. Nevertheless presentation of the pictures of the boys resulted in the pedophilic offender in a significant activation of the attention network and the right orbitofrontal cortex. In contrast to the controls there was no activation of left hemispheric areas relevant for speech. The study design will be continued in a larger sample to examine whether there is a possible neurobiological correlate of pedophilia which can be changed by therapeutic interventions.

Adult↗
PubMed1999

Antipsychotic drug effects on motor activation measured by functional magnetic resonance imaging in schizophrenic patients.

Brain function and laterality in schizophrenia were investigated by means of a simple motor task with a self-generated left-hand sequential finger opposition (SFO) using a whole-brain high-speed (100 ms per slice) functional imaging technique. Neuroleptic-naïve, acutely ill schizophrenic patients were compared to schizophrenic patients under stable neuroleptic medication and matched controls. The goal was to evaluate both the motor function in first-episode patients and possible effects of different neuroleptic treatments on functional MRI results. Forty patients satisfying ICD 10 criteria (F20.x) for schizophrenia and sex- and age-matched healthy volunteers participated in this study. All subjects underwent fMRI examinations on a conventional 1.5 T MR unit. The primary sensorimotor cortex and the high-order supplementary motor area (SMA) were evaluated. There was a close similarity in the activation of the primary and high-order (SMA) sensorimotor areas between first-episode schizophrenic patients and controls. In contrast, a significant reduction in the overall blood oxygen level dependent (BOLD) response was seen in sensorimotor cortices (contra- and ipsilateral) in schizophrenic patients under stable medication with typical neuroleptics. This effect was not present in patients treated with atypical antipsychotics. Both antipsychotic treatments, however, led to a significant reduction in activation of the SMA region compared to controls and neuroleptic-naïve subjects. Thus, the present study provides no evidence for the localized involvement of the primary motor cortex or the SMA as a relatively stable vulnerability marker in schizophrenia. There is, however, strong evidence that neuroleptics themselves influence fMRI activation patterns and that there are major differences between typical neuroleptics and atypical antipsychotics.

Adult↗
PubMed1998

[Medial medullary infarct].

Medial medullary infarct is a rare type of brain stem infarction first described in 1908. It was only since the broad use of MRI that an accurate clinical topographical correlation could be documented in survivors. We observed two patients; one of them had an anteromedial unilateral infarction in the upper medulla, and the clinical picture was characterized by contralateral hemiparesis, facial weakness, dysarthria and palatal weakness. The outcome was good. The second patient however showed a severe tetraparesis with only minor brain stem signs, secondary to bilateral anteromedian infarction with a large craniocaudal extension. He survived with severe residual impairment. The most likely cause of infarction was arteriosclerosis of the A. vertebralis and A. spinalis anterior, respectively. These two different cases suggest that the medial medullary syndrome is heterogeneous comprising small unilateral infarctions with mild clinical signs as well as large bilateral infarctions with a poor outcome.

Aged↗
PubMed1998

Streptokinase-induced activation of the kallikrein-kinin system and of the contact phase in patients with acute myocardial infarction.

Thrombolytic therapy in acute myocardial infarction (AMI) is hampered by a considerable reocclusion rate. Thrombin activity is enhanced, and contact-system activation via plasminemia might be possible. Prospectively we examined the contact phase and the kallikrein-kinin system and additional molecular markers of hemostasis and fibrinolysis in AMI. In 22 patients with AMI, blood sampling was performed at admission and < or =10 days afterward. Eleven patients received 1.5 Mio U streptokinase (group A) and were compared with 11 AMI patients without thrombolytic therapy (group B). All patients had systemic heparinization (5,000 IU bolus, i.v.; 1,000 IU/h, i.v.). In group A (vs. group B), the kallikrein-factor XII system was significantly activated (3 h after start of therapy): kallikrein activity 140 +/- 41 (vs. 43 +/- 8) U/L (p < 0.05); kallikrein inhibition 87 +/- 9 (vs. 113 +/- 7%; p < 0.05), and factor XII 70 +/- 14 (vs. 94 +/- 6%). C1 inhibitor and factor XII inhibition were decreased. High-molecular-weight kininogen consumption indicating bradykinin generation was enhanced (p < 0.01). In group A, thrombin activity (TAT) was increased, and a hypercoagulative state with increased fibrin degradation products (d-dimer) was found. Plasmin activation in group A was reflected by decreased plasminogen and antiplasmin levels (p < 0.01). The findings indicate that streptokinase induces activation of the contact phase-kinin system in vivo associated with a consecutive increase of thrombin and bradykinin generation. Activation of this pathway might substantially contribute to reocclusion after initially successful thrombolytic therapy and to hypotensive reactions observed after streptokinase.

Acute Disease↗
PubMed1996

Contrast sensitivity with monofocal and bifocal intraocular lenses.

Bifocal intraocular lenses (BIOLs) reduce image contrast. We measured contrast sensitivity (CS) to evaluate the clinical significance of the loss in image contrast. Four groups were compared: 15 patients with a monofocal IOL, 13 with the True Vista BIOL, 13 with the AcuraSee BIOL, 11 with the diffractive BIOL. CS was measured using the Mentor B-VAT II-SG. Distance CS was slightly better in monofocal eyes than in all bifocal eyes, and distance CS was considerably better than near CS in eyes with the True Vista or the AcuraSee BIOL. With the diffractive BIOL, values were about the same at distance and near focus. Our results demonstrate that BIOLs reduce CS. thereby performing differently: both True Vista and AcuraSee favor distance vision, while the diffractive BIOL provides about the same contrast at distance and near focus.

Aged↗
PubMed1988

Structure and expression of the gene coding for the alpha-subunit of DNA-dependent RNA polymerase from the chloroplast genome of Zea mays.

The rpoA gene coding for the alpha-subunit of DNA-dependent RNA polymerase located on the DNA of Zea mays chloroplasts has been characterized with respect to its position on the chloroplast genome and its nucleotide sequence. The amino acid sequence derived for a 39 Kd polypeptide shows strong homology with sequences derived from the rpoA genes of other chloroplast species and with the amino acid sequence of the alpha-subunit from E. coli RNA polymerase. Transcripts of the rpoA gene were identified by Northern hybridization and characterized by S1 mapping using total RNA isolated from maize chloroplasts. Antibodies raised against a synthetic C-terminal heptapeptide show cross reactivity with a 39 Kd polypeptide contained in the stroma fraction of maize chloroplasts. It is concluded that the rpoA gene is a functional gene and that therefore, at least the alpha-subunit of plastidic RNA polymerase, is expressed in chloroplasts.

Amino Acid Sequence↗
PubMedDate not supplied

[Anatomic reduction and monosegmental fusion for high-grade developmental spondylolisthesis L5/S1].

INTRODUCTION: Developmental spondylolisthesis leads to lumbosacral kyphosis with retroversion of the sacrum and lumbar hyperlordosis. The overall sagittal profile of the spine is affected. The deformity is progressive during growth. This retrospective study describes a technique for complete reduction with clinical and radiological evaluation. PATIENTS: Thirty-four patients (mean age 16 years 3 months, 10 males, 24 females) with severe developmental spondylolisthesis L5/S1 (Meyerding grades 3 to 5) were operated on between February 1997 and July 2002. METHOD: Reduction was achieved by temporary transpedicular instrumentation of L4. These screws were removed at the end of the operation or 12 weeks later. RESULTS: Mean slippage was corrected from 76 % preoperatively to 10 % postoperatively. Segmental kyphosis L5/S1 improved from + 21 degrees preoperatively to - 7 degrees postoperatively. Sacral inclination was 34 degrees preoperatively, 43 degrees postoperatively, and 47 degrees at latest follow-up. 76 % of the patients were pain free at the latest follow-up. In 4 patients a fusion at L4/5 was performed due to subsequent decompensation. CONCLUSION: The technique described allows for a nearly anatomic reduction with correction of slippage as well as segmental kyphosis. Correction of the local deformity with monosegmental fusion L5/S1 improves dramatically the overall sagittal profile of the spine. Fusion of the primarily healthy segment L4/5 can be avoided.

Adolescent↗