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Biomedical subjects

M Hartmann

Publications and source records attributed to M Hartmann.

At least 19 recordsLinked to original sources
PubMed2006

30 day results from the SPACE trial of stent-protected angioplasty versus carotid endarterectomy in symptomatic patients: a randomised non-inferiority trial.

BACKGROUND: Carotid endarterectomy is effective in stroke prevention for patients with severe symptomatic carotid-artery stenosis, and carotid-artery stenting has been widely used as alternative treatment. Since equivalence or superiority has not been convincingly shown for either treatment, we aimed to compare the two. METHODS: 1200 patients with symptomatic carotid-artery stenosis were randomly assigned within 180 days of transient ischaemic attack or moderate stroke (modified Rankin scale score of < or =3) carotid-artery stenting (n=605) or carotid endarterectomy (n=595). The primary endpoint of this hospital-based study was ipsilateral ischaemic stroke or death from time of randomisation to 30 days after the procedure. The non-inferiority margin was defined as less than 2.5% on the basis of an expected event rate of 5%. Analyses were on an intention-to-treat basis. This trial is registered at Current Controlled Trials with the international standard randomised controlled trial number ISRCTN57874028. FINDINGS: 1183 patients were included in the analysis. The rate of death or ipsilateral ischaemic stroke from randomisation to 30 days after the procedure was 6.84% with carotid-artery stenting and 6.34% with carotid endarterectomy (absolute difference 0.51%, 90% CI -1.89% to 2.91%). The one-sided p value for non-inferiority is 0.09. INTERPRETATION: SPACE failed to prove non-inferiority of carotid-artery stenting compared with carotid endarterectomy for the periprocedural complication rate. The results of this trial do not justify the widespread use in the short-term of carotid-artery stenting for treatment of carotid-artery stenoses. Results at 6-24 months are awaited.

Aged↗
PubMed2006

Precision measurement of the quasifree pn-->dvarphi reaction close to threshold.

The quasifree pn-->dvarphi reaction has been studied at the Cooler Synchrotron COSY-Jülich, using the internal proton beam incident on a deuterium cluster-jet target and detecting a fast deuteron in coincidence with the K+K- decay of the varphi meson. The energy dependence of the total and differential cross sections are extracted for excess energies up to 80 MeV by determining the Fermi momentum of the target neutron on an event-by-event basis. Though these cross sections are consistent with s-wave production, the kaon angular distributions show the presence of p waves at quite a low energy. Production on the neutron is found to be stronger than on the proton but not by as much as for the eta meson.

Journal Article↗
PubMed2006

Diagnostic performance of spectroscopic and perfusion MRI for distinction of brain tumors.

OBJECTIVE: To assess the value of spectroscopic and perfusion MRI for glioma grading and for distinguishing glioblastomas from metastases and from CNS lymphomas. METHODS: The authors examined 79 consecutive patients with first detection of a brain neoplasm on nonenhanced CT scans and no therapy prior to evaluation. Spectroscopic MRI; arterial spin-labeling MRI for measuring cerebral blood flow (CBF); first-pass dynamic, susceptibility-weighted, contrast-enhanced MRI for measuring cerebral blood volume; and T1-weighted dynamic contrast-enhanced MRI were performed. Receiver operating characteristic analysis was performed, and optimum thresholds for tumor classification and glioma grading were determined. RESULTS: Perfusion MRI had a higher diagnostic performance than spectroscopic MRI. Because of a significantly higher tumor blood flow in glioblastomas compared with CNS lymphomas, a threshold value of 1.2 for CBF provided sensitivity of 97%, specificity of 80%, positive predictive value (PPV) of 94%, and negative predictive value (NPV) of 89%. Because CBF was significantly higher in peritumoral nonenhancing T2-hyperintense regions of glioblastomas compared with metastases, a threshold value of 0.5 for CBF provided sensitivity, specificity, PPV, and NPV of 100%, 71%, 94%, and 100%. Glioblastomas had the highest tumor blood flow values among all other glioma grades. For discrimination of glioblastomas from grade 3 gliomas, sensitivity was 97%, specificity was 50%, PPV was 84%, and NPV was 86% (CBF threshold value of 1.4), and for discrimination of glioblastomas from grade 2 gliomas, sensitivity was 94%, specificity was 78%, PPV was 94%, and NPV was 78% (CBF threshold value of 1.6). CONCLUSION: Perfusion MRI is predictive in distinguishing glioblastomas from metastases, CNS lymphomas and other gliomas vs MRI and magnetic resonance spectroscopy.

Brain Neoplasms↗
PubMed2006

Near-threshold production of phi mesons in pp collisions.

The pp-->ppphi reaction has been studied at the Cooler Synchrotron COSY-Jülich, using the internal beam and ANKE facility. Total cross sections have been determined at three excess energies epsilon near the production threshold. The differential cross section closest to threshold at epsilon=18.5 MeV exhibits a clear S wave dominance as well as a noticeable effect due to the proton-proton final-state interaction. Taken together with data for ppomega production, a significant enhancement of the phi/omega ratio of a factor 8 is found compared to predictions based on the Okubo-Zweig-Iizuka rule.

Journal Article↗
PubMed2006

Intraoperative MRI for interventional neurosurgical procedures and tumor resection control in children.

INTRODUCTION: Despite the introduction of neuronavigational systems, radical tumor removal is still problematic in many neurosurgical procedures. Thus, direct intraoperative imaging for tumor resection control was implemented with an intraoperative magnetic resonance imaging (ioMRI) scanner installed in the operating room. Whereas most procedures with ioMRI were carried out in adults, we summarize 7 years of experience using ioMRI in children for interventional neurosurgical procedures or for tumor resection control. METHOD: An open magnetic resonance scanner (Magnetom Open 0.2 T) was installed in the neurosurgical operating room. For tumor resection control, ioMRI was performed in 35 procedures. After the ioMRI scans were analyzed with respect to quality, the identification of residual tumor was considered by the attending neuroradiologist and neurosurgeon. If residual tumor tissue was present, a new three-dimensional (3D) dataset was acquired to update the neuronavigation; subsequently, the tumor resection was extended. In all these procedures, the results of the ioMRI were checked by an early postoperative high-field magnetic resonance imaging (MRI) study. In addition, ioMRI was carried out in ten other children to monitor interventional neurosurgical procedures. RESULTS: In all children, ioMRI was adequate both for tumor resection control and monitoring of interventional procedures. Primary radical removal of tumor was reached in 40% as confirmed by ioMRI, but in 60% of the patients, the tumor resection procedure was extended after residual tumor was detected using the new 3D dataset for navigational update. By using ioMRI, radical tumor removal improved up to 83% as confirmed by early postoperative MRI. Procedure-related complications were not seen in our series. For all MR-guided biopsies, histology findings could be confirmed, and aspiration of intracranial cysts or abscesses could be monitored online. CONCLUSION: IoMRI using the open magnetom is suitable for detecting residual tumor tissue, can compensate for the phenomenon of brain shift using a new intraopertive 3D dataset for extended tumor resection, and is capable of monitoring interventional neurosurgical procedures. By using ioMRI for tumor resection control, the degree of tumor resection could be significantly improved.

Adolescent↗
PubMed2006

MRI growth patterns of plexiform neurofibromas in patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with an incidence of 1:3000. Approximately 30% of NF1 patients develop plexiform neurofibromas (PNF) which often cause severe clinical deficits. We studied the growth patterns of 256 plexiform neurofibromas (PNF) by magnetic resonance imaging (MRI) and associated disfigurement and functional deficits to determine whether there are definable growth types of these tumors. Retrospectively, we evaluated MRI scans obtained during 1997 to 2003 of 256 plexiform neurofibromas from 202 patients with NF1. Clinical investigation was carried out at the same time as the MRI scans. We identified three growth patterns: superficial in 59, displacing in 76, and invasive growth in 121 tumors. The majority (52%) of invasive PNF were found in the face, head and neck area. While superficial PNF primarily caused aesthetic problems, displacing PNF led in most cases to aesthetic problems and pain, while invasive PNF led mainly to functional deficits and disfigurement. Our study demonstrates that PNF have different growth patterns that are associated with specific clinical features. Classification of PNF may open new opportunities in clinical management, especially regarding decisions and options associated with surgical intervention.

Adolescent↗
PubMed2006

[The side effects of antiretroviral therapy].

The introduction of highly active antiretroviral therapy (HAART) has resulted in tremendous improvements in morbidity and mortality in HIV-infected patients. However, the use of these drugs has coincided with an increasing number of reports of gastrointestinal, hepatic or metabolic side effects. Soon after beginning antiretroviral treatment drug rashes, hypersensitivity reactions, immune reconstitution syndrome or injection site reaction are frequently seen. Under HAART dyslipidemia, impaired glucose metabolism and elevated liver function are observed. In the later treatment phase, lipodystrophy, a combination of peripheral lipoatrophy and central fat accumulation, occurs.

Anti-HIV Agents↗
PubMed2006

["Second opinion centers". Approach for improving the quality of treatment for testicular tumors].

According to estimations of the German Cancer Research Center in Heidelberg, the management of germ cell tumors in Germany is characterized by a marked difference between the actual mortality and the mortality to be expected with adequate implementation of the therapy standard. Our aim is to reduce the mortality rate by introducing a treatment procedure supported by a second opinion center.

Cancer Care Facilities↗
PubMed2006

3.0 Tesla contrast-enhanced MR angiography of carotid artery stents: in vitro measurements as compared with 1.5 Tesla.

BACKGROUND AND PURPOSE: To assess the appearance of carotid artery stents at 3.0 Tesla contrast enhanced magnetic resonance angiography (CE-MRA) as compared with 1.5 Tesla. METHODS: 19 stents (GUIDANT Acculink, GUIDANT Dynalink, BOSTON SCIENTIFIC SMART Neuroform, GUIDANT Omnilink, EV3 Protege, BOSTON SCIENTIFIC Carotid Wallstent, ABBOTT Xact) of different materials (nitinol, stainless steal, cobalt alloy) and different sizes (4.0 mm-10.0 mm) were investigated regarding their appearance on CE-MRA at 3.0 Tesla and at 1.5 Tesla. For each stent artificial lumen narrowing (ALN) was calculated based on a pixel-by-pixel profile of the contrast-to-noise-ratio giving an objective indicator for the size of the evaluable stent diameter. RESULTS: Only in two stents (Omnilink 7.0 mm, Omnilink 10.0 mm) was ALN higher at 3.0 Tesla relative to 1.5 Tesla. In all other stents ALN at 3.0 Tesla was the same or even lower as compared with 1.5 Tesla. In contrast to the ferromagnetic stents where ALN was typically higher than 85%, in most of the nitinol stents (Acculink, Dynalink, Neuroform, Protege) ALN was below 35%. In the Xact stents ALN was generally 100% at 1.5 Tesla and ranged between 31.8% and 100% at 3.0 Tesla. CONCLUSION: CE-MRA after carotid artery stenting is considerably impaired by ALN both at 1.5 Tesla and at 3.0 Tesla. Nevertheless, CE-MRA is well suited for the examination of carotid artery stents made of nitinol at both field strengths. Stent manufacturers should be aware of potential artifacts caused by their stents during noninvasive diagnostic methods such as CE-MRA.

Alloys↗
PubMed2006

Repeated digital substraction angiography after perimesencephalic subarachnoid hemorrhage?

BACKGROUND AND PURPOSE: In patients with perimesencephalic subarachnoid hemorrhage (pSAH) DSA is recommended to exclude aneurysms to due false negative findings in CT-angiography. However, whether a second DSA is indicated during the clinical course to exclude--in addition to aneurysms--fistulas, too, is still under debate. We aimed to evaluate the benefit of repeated DSA in patients with pSAH. METHODS: The source of data was a prospective database set up at the neurological, neurosurgical and neuroradiological departments in our institution. A total of 69 patients with pSAH were enrolled and analyzed by reviewing the medical records and neuroradiological findings. RESULTS: 68 patients presented with Hunt & Hess Grade I-II and one patient with Hunt & Hess Grade III. Median in-hospital stay was 8 days (3-22). In 2 patients mild vasospasm were diagnosed. DSA was performed in all patients at least once. DSA was repeated in 38 patients (55%) after a median of 7 (3-21) days. None of the repeated DSA did show any additional distinctive features with respect to the first DSA. CONCLUSIONS: In our opinion the procedure of repeating DSA in patients with pSAH is likely to become obsolete. One DSA should be performed prior to discharge--and subsequent to possible vasospasm--to exclude hemorrhage caused by aneurysms of the posterior circulation mimicking a perimesencephalic SAH pattern.

Angiography, Digital Subtraction↗
PubMed2006

Recurrent varicose veins: sonography-based re-examination of 210 patients 14 years after ligation and saphenous vein stripping.

BACKGROUND: The objective of this study was to assess the frequency of varicose recurrence 14 years after flush ligation of the saphenofemoral (SFJ) or saphenopopliteal (SPJ) junction with additional stripping of the incompetent saphenous vein. PATIENTS AND METHODS: Our study group comprised 245 extremities of 210 patients operated upon in 1990 for either great saphenous vein (GSV) or small saphenous vein (SSV) incompetence. Limbs were assessed with Duplex ultrasound by a practitioner other than the original surgeon and relevant patient data was recorded. RESULTS: In 68.5% of re-examined limbs Duplex imaging provided no evidence for recurrent varicose veins at the former SFJ or SPJ. This included 15 legs (= 6.1%) where reflux immediately proximal to the junction but originating from adjacent veins (i.e. pudendal vein, epigastrical vein) was detected. In 31.5%, reflux from the operated SFJ or SPJ (junctional recurrence) was detected but only a minor percentage of legs (6.9%) had actually developed a clinically relevant recurrent varicosity (> 3 mm in diameter) branching out from the former junction and requiring treatment. Patients with a BMI < 30 were less likely to suffer recurrent varicose veins (no recurrence in 72.7%) than patients with a BMI > or = 30 (no recurrence in 54.5%). CONCLUSIONS: 14 years after flush ligation of the SFJ or SPJ with stripping of the incompetent saphenous vein, junctional recurrences were found in less than one-third of re-examined extremities. In the absence of surgical errors, we must assume neovascularisation as cause for these recurrences. Duplex US determined a clinically relevant recurrence (> 3 mm in diameter) in only 7% of limbs. Post-operative varices seem to develop less often after SPJ surgery than after SFJ surgery and according to our data, obesity (BMI > or = 30) constitutes a significant risk factor.

Adult↗
PubMed2006

[Cranial manifestation of Wegener's granuolomatosis: CT and MRI characteristics].

Wegener's granulomatosis is a rare systemic granulomatous disease which primarily involves the upper and lower respiratory tract and the kidneys. In addition the orbits, the peripheral and the central nervous system may also be affected. Computed tomography and magnetic resonance imaging have been proven to be quite useful for the detection of these lesions, for assessment of the extent of involvement, and for documentation of response to therapy. The drawback of CT and MR studies is that they lack specificity. Characteristic imaging findings for WG is a medial wall destruction of the maxillary sinus with gross thickening of the anterior and infratemporal walls with relatively low soft tissue proliferation. On T2-weighted MR images the granulomatous tissue appears markedly hypo-intense with dense enhancement. Although these findings are not specific, if they are obvious, Wegener's granulomatosis should be considered in the differential diagnosis.

Brain↗
PubMed2006

Ion mobility spectrometry for food quality and safety.

Ion mobility spectrometry is known to be a fast and sensitive technique for the detection of trace substances, and it is increasingly in demand not only for protection against explosives and chemical warfare agents, but also for new applications in medical diagnosis or process control. Generally, a gas phase sample is ionized by help of ultraviolet light, ss-radiation or partial discharges. The ions move in a weak electrical field towards a detector. During their drift they collide with a drift gas flowing in the opposite direction and, therefore, are slowed down depending on their size, shape and charge. As a result, different ions reach the detector at different drift times, which are characteristic for the ions considered. The number of ions reaching the detector are a measure of the concentration of the analyte. The method enables the identification and quantification of analytes with high sensitivity (ng l(-1) range). The selectivity can even be increased - as necessary for the analyses of complex mixtures - using pre-separation techniques such as gas chromatography or multi-capillary columns. No pre-concentration of the sample is necessary. Those characteristics of the method are preserved even in air with up to a 100% relative humidity rate. The suitability of the method for application in the field of food quality and safety - including storage, process and quality control as well as the characterization of food stuffs - was investigated in recent years for a number of representative examples, which are summarized in the following, including new studies as well: (1) the detection of metabolites from bacteria for the identification and control of their growth; (2) process control in food production - beer fermentation being an example; (3) the detection of the metabolites of mould for process control during cheese production, for quality control of raw materials or for the control of storage conditions; (4) the quality control of packaging materials during the production of polymeric materials; and (5) the characterization of products - wine being an example. The challenges of such applications were operation in humid air, fast on-line analyses of complex mixtures, high sensitivity - detection limits have to be, for example, in the range of the odour limits - and, in some cases, the necessity of mobile instrumentation. It can be shown that ion mobility spectrometry is optimally capable of fulfilling those challenges for many applications.

Cheese↗
PubMed2006

Neuromyelitis optica (Devic's syndrome) as first manifestation of systemic lupus erythematosus.

Neurologic symptoms rarely occur as presenting feature of systemic lupus erythematosus (SLE). We describe a 37-year old woman who presented with several episodes of transverse myelitis and optic neuritis. Clinical, radiologic and laboratory findings were compatible with neuromyelitis optica (NMO). Seven years after disease onset clinical and laboratory findings were diagnostic for SLE. This case illustrates that NMO may represent a first manifestation of SLE for many years.

Adult↗
PubMed2006

Prolonged high-pressure treatments in mammalian skeletal muscle result in loss of functional sodium channels and altered calcium channel kinetics.

Activation and inactivation of ion channels involve volume changes from conformational rearrangements of channel proteins. These volume changes are highly susceptible to changes in ambient pressure. Depending on the pressure level, channel function may be irreversibly altered by pressure. The corresponding structural changes persist through the post-decompression phase. High-pressure applications are a useful tool to evaluate the pressure dependence as well as pressure limits for reversibility of such alterations. Mammalian cells are only able to tolerate much lower pressures than microorganisms. Although some limits for pressure tolerance in mammalian cells have been evaluated, the mechanisms of pressure-induced alteration of membrane physiology, in particular of channel function, are unknown. To address this question, we recorded fast inward sodium (I(Na)) and slowly activating L-type calcium (I(Ca)) currents in single mammalian muscle fibers in the post-decompression phase after a prolonged 3-h, high-pressure treatment of up to 20 MPa. I(Na) and I(Ca) peak amplitudes were markedly reduced after pressure treatment at 20 MPa. This was not from a general breakdown of membrane integrity as judged from in situ high-pressure fluorescence microscopy. Membrane integrity was preserved even for pressures as high as 35 MPa at least for pressure applications of shorter durations. Therefore, the underlying mechanisms for the observed amplitude reductions have to be determined from the activation (time-to-peak [TTP]) and inactivation (tau(dec)) kinetics of I(Na) and I(Ca). No major changes in I(Na) kinetics, but marked increases, both in TTP and tau(dec) for I(Ca), were detected after 20 MPa. The apparent molecular volume changes (activation volumes) deltaV(double dagger) for the pressure-dependent irreversible alteration of channel gating approached zero for Na+ channels. For Ca2+ channels, deltaV(double dagger) was very large, with approx 2.5-fold greater values for channel activation than inactivation (approx 210 A3). We conclude, that in skeletal muscle, high pressure differentially and irreversibly affects the gating properties and the density of functional Na+ and Ca2+ channels. Based on these results, a model of high pressure-induced alterations to the channel conformation is proposed.

Animals↗
PubMed2005

Cerebrovascular manifestations of Takayasu arteritis in Europe.

OBJECTIVES: Takayasu arteritis is well known as a cause of stroke in Asia but has rarely been described in the Western world. Here we report the clinical and neuroimaging follow-up of a series of patients with Takayasu arteritis from Europe. METHODS: Seventeen consecutive patients who fulfilled the diagnostic criteria for Takayasu arteritis of the American College of Rheumatology were evaluated on follow-up by standardized neurological examination, sonography and MRI. RESULTS: At follow-up almost 20 yr after onset of symptoms, the subclavian artery and the common carotid artery were often affected. In addition, evidence of intracranial pathology was found in seven patients. In contrast to the severe vessel involvement, the neurological state was stable. Two patients had suffered from stroke before the diagnosis was made and therapy was initiated, and one patient had recurrent transient ischaemic attacks. Intermittent dizziness was associated with pathology of the vertebral and basilar arteries. However, clinical symptoms of subclavian steal syndrome were rare. CONCLUSION: This case series shows that the clinical neurological course of Takayasu arteritis on treatment is benign in most cases despite the severe vascular involvement.

Adolescent↗