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Biomedical subjects

G Strasser

Publications and source records attributed to G Strasser.

At least 19 recordsLinked to original sources
PubMed2004

Pineal gland abnormalities in Langerhans cell histiocytosis.

BACKGROUND: The most common types of central nervous system (CNS) disease in Langerhans cell histiocytosis (LCH) comprise involvement of the hypothalamic-pituitary region (HPR) and neurodegenerative changes in the cerebellum, basal ganglia or pons. In the review process of magnetic resonance images (MRI) from 129 LCH patients a high frequency of cysts within or large pineal glands was noted by chance. PROCEDURE: To prove whether this observation was specific for LCH or not, we compared MRI findings of the HPR in LCH patients with a control group of 55 non-LCH patients with the same age and sex distribution. RESULTS: In LCH patients, the pineal gland was significantly larger and also the number of pineal cysts was significantly higher as compared to the control group. No difference was found regarding the size or frequency of cystic changes between patients who had received chemotherapy prior to the MRI and untreated patients. In the LCH patients, we further found a significant correlation of pineal gland enlargement with involvement of the HPR, but not with neurodegenerative changes. Analysis of melatonin (the principal hormone of the pineal gland) levels in 24 hr urine in 14 LCH patients did not reveal a melatonin deficiency or overproduction in the LCH group as compared to 6 normal controls. CONCLUSIONS: The pineal gland is another site of possible CNS involvement in LCH. LCH CNS patients did not show an overt disturbance in melatonin levels. The role of the pineal gland in CNS LCH remains to be defined.

Adolescent↗
PubMed2003

["Disappearance" of retroperitoneal vessels - a case report].

We report the ultrasound findings in a case of pneumo-retroperitoneum. The 74-year-old patient was admitted because of severe dyspnoea. Chest X-ray revealed a left-sided pleural effusion, and a drainage was performed. Later on the patient for the first time complained about severe pain in the lower abdomen. Ultrasound of the abdomen was performed. Sonographically, it was remarkably difficult to obtain images of the right kidney and the retroperitoneal vessels, as massive reverberation artifacts in the retroperitoneum were present. Plain radiography of the abdomen revealed free retroperitoneal and intraabdominal gas. At laparotomy a perforated diverticulitis of the sigma was discovered. Postoperative follow-up was uneventful, but the recurrent pleural effusion was later confirmed to be due to a malignant mesothelioma. This article discusses the characteristic sonomorphologic features of pneumo-retroperitoneum and its differential diagnosis. Although free retroperitoneal air is a rare condition, it is crucial for the examiner to be aware of the characteristic sonographic findings in order to initiate appropriate therapy.

Aged↗
PubMed2002

Wannier-Stark states in finite superlattices.

Individual Wannier-Stark states are resolved in a current experiment over a wide electric-field range for a 5 and 4 period finite superlattice utilizing a hot-electron transistor. The observed field dependence of the tunneling transmission through the various states directly resembles the progressive localization of the wave functions. The basic transport through Wannier-Stark states in short-period superlattices is identified to be coherent. By tuning the Wannier-Stark state splitting with electric field into the optical phonon energy, the opening of new LO-phonon mediated transport paths is observed.

Journal Article↗
PubMed2002

Ultrafast coherent electron transport in semiconductor quantum cascade structures.

Coherent electron transport is studied in an electrically driven quantum cascade structure. Ultrafast quantum transport from the injector into the upper laser state is investigated by midinfrared pump-probe experiments directly monitoring the femtosecond saturation and subsequent recovery of electrically induced optical gain. We demonstrate for the first time pronounced gain oscillations giving evidence for a coherent electron motion. The coexistence of a long dephasing time of quantum coherence and high Coulomb scattering rates in the injector points to the occurrence of scattering-induced coherence in electron transport.

Journal Article↗
PubMed2002

Intersubband transport in quantum wells in strong magnetic fields mediated by single- and two-electron scattering.

We show theoretically that in quantum wells subjected to a strong magnetic field the intersubband current peaks at magnetic field values, which reveal the underlying specific intersubband scattering mechanism. We have designed and grown a superlattice structure in which such current oscillations are clearly visible, and in which the transition from the purely single-electron to the mixed single- and two-electron scattering regimes can be observed by tuning the applied voltage bias. The measurements were conducted in ultrahigh magnetic fields (up to 45 T) to obtain the full spectrum of the current oscillations.

Journal Article↗
PubMed2002

[Quality management in a radiology department].

PURPOSE: To increase the quality of internal and external interactions (patients, clinical colleagues, technicians, radiologists) in a department of radiology. METHOD: Accompanied by a well-experienced adviser workshops have been performed dealing with different topics like "contact to patients," "performance of the radiological report and interaction with the referring colleague" or "research and teaching." A catalogue of different actions was defined to reduce hindrances within the internal and external work-flow. RESULTS: A total number of 53 actions was defined and related to different persons who were responsible for the realisation of the measures within a time interval. Six months after starting the quality management 46 (86%) of the defined actions were realised successfully, and another 4 (8%) measures were still running. There was a moderate increase of satisfaction of the patients and clinical colleagues considering the waiting time. CONCLUSIONS: A quality management in a radiological department allows an optimisation of the internal and external interactions. However, the guidance of a well-experienced adviser is as essential as the continuous control of successful finished measures.

Education↗
PubMed2002

Sequential MRI in a case of Creutzfeldt-Jakob disease.

A 48-year-old man suddenly developed clinically and electroencephalographically nonspecific dementia. On MRI sequences, only diffusion-weighted images (DWI) of the cortex were unequivocally pathological. Obvious atrophy and basal ganglia signal changes appeared only 9 months after the onset. Brain biopsy confirmed Creutzfeldt-Jakob disease (CJD). In rapidly progressive dementia, we recommend DWI for early diagnosis of CJD.

Brain↗
PubMed2002

Revision of the Kotz type of tumour endoprosthesis for the lower limb.

In 251 patients over a period of 15 years an uncemented Kotz modular femoral and tibial reconstruction mega prosthesis was implanted after resection of a malignant tumour of the lower limb. Twenty-one patients (8.4%) underwent revision for aseptic loosening, again using an uncemented prosthesis, and five of these required a further revision procedure. The median follow-up time from the first revision was 60 months (11 to 168) and after a second revision, 33 months (2 to 50). The probability of a patient avoiding aseptic loosening for ten years was 96% for a proximal femoral, 76% for a distal femoral and 85% for a proximal tibial implant. At the time of follow-up all radiographs were assessed according to the International Symposium of Limb Salvage criteria. The first radiological signs of aseptic loosening were always seen at the most proximal or distal part of the anchorage stem at a mean of 12 months (4 to 23) after the first implantation. Using the Musculoskeletal Tumor Society score for evaluation, the clinical results showed a mean of 88% of normal function.

Adolescent↗
PubMed2001

Towards functional group-specific detection in high-performance liquid chromatography using mid-infrared quantum cascade lasers.

A distributed feedback quantum cascade laser was applied for the first time as a powerful light source for mid-infrared (MIR) detection in liquid chromatography. Fructose and glucose in red wine were separated with an isocratic HPLC system, which was connected to a custom-made flow cell. This flow cell was constructed of two diamond windows with adjustable spacing and two hollow wave-guides for guiding the incoming and outgoing light. The HPLC column based on an ion-exchange resin with calcium(II) counter ion was run at 80 degrees C with 0.04% formic acid as the mobile phase. Under these conditions the carbohydrates could not be completely separated from the organic acids also present in wine. However, the emission of the laser at 1067 cm(-1) matches the absorption maximum of fructose and glucose, whereas the organic acids do not absorb appreciably at this wavenumber. Thus group-specific detection could be achieved. Additionally, the optical path length could be increased from 25 to 125 microm, which is very promising in gaining enhanced sensitivity compared to Fourier transform IR detection.

Calibration↗
PubMed2001

Resonant tunneling mediated by resonant emission of intersubband plasmons.

We study tunneling through resonant tunneling diodes (RTD) with very long emitter drift regions (up to 2 microm). In such diodes, charge accumulation occurs near the double barrier on the emitter side, in a self-induced potential pocket. This leads to a substantial enhancement of the wave function overlap between states of the pocket and the RTD, and, consequently, to increased off-resonant current mediated by various scattering processes. For RTD with the longest drift region (2 microm), an additional strong current peak is observed between the first and the second resonant peaks. We attribute this pronounced feature to the intersubband transitions mediated by resonant emission of intersubband plasmons.

Journal Article↗
PubMed2000

Cervical osteophytes impinging on the pharynx: importance of size and concurrent disorders for development of aspiration.

OBJECTIVE: This study evaluated the clinical significance of cervical osteophytes impinging on the pharynx in patients with dysphagia and the importance of concurrent disorders that may affect swallowing function. MATERIALS AND METHODS: On videofluoroscopy, anterior cervical osteophytes were found in 55 (32 men, 23 women; mean age, 69 years) of 3318 patients with dysphagia (1.7%). Coexisting diseases that affected swallowing function were found in 28 patients (stroke, n = 7; thyroidectomy, n = 7; tongue base or laryngeal cancer surgery, n = 5; other diseases, n = 9). Swallowing function was assessed with videofluoroscopy evaluating epiglottic tilting, laryngeal closure, impression of the hypopharynx, pharyngeal residue, and aspiration. RESULTS: With advancing age, the probability of aspiration (odds ratio, 1.07; p < 0.05) and of enlarging osteophytes (odds ratio, 1.26; p < 0.01) increased; the probability was higher for osteophytes at more than one vertebrae (odds ratio, 8.00; p < 0.01) and for concurrent diseases (odds ratio, 8.02; p < 0.01). Aspiration was found in 75% of patients with osteophytes larger than 10 mm and in 34% with osteophytes smaller than or equal to 10 mm. In 88% of patients with small osteophytes who aspirated, other diseases affected swallowing function. CONCLUSION: Aspiration is common in patients with dysphagia and cervical osteophytes larger than 10 mm. Aspiration is rare in patients with osteophytes smaller than or equal to 10 mm unless these patients suffer from other disorders that may affect swallowing.

Cervical Vertebrae↗
PubMed1999

Integrators of the cytoskeleton that stabilize microtubules.

Sensory neurodegeneration occurs in mice defective in BPAG1, a gene encoding cytoskeletal linker proteins capable of anchoring neuronal intermediate filaments to actin cytoskeleton. While BPAG1 null mice fail to anchor neurofilaments (NFs), BPAG1/NF null mice still degenerate in the absence of NFs. We report a novel neural splice form that lacks the actin-binding domain and instead binds and stabilizes microtubules. This interaction is functionally important; in mice and in vitro, neurons lacking BPAG1 display short, disorganized, and unstable microtubules defective in axonal transport. Ironically, BPAG1 neural isoforms represent microtubule-associated proteins that when absent lead to devastating consequences. Moreover, BPAG1 can functionally account for the extraordinary stability of axonal microtubules necessary for transport over long distances. Its isoforms interconnect all three cytoskeletal networks, a feature apparently central to neuronal survival.

Actin Cytoskeleton↗
PubMed1999

Mycobacteria other than tuberculosis with an emphasis on Mycobacterium xenopi in clinical specimens from AIDS patients at the University Hospital of Vienna from 1989 to 1996.

This study was carried out to provide an overview of the frequency of various mycobacterial species isolated from AIDS patients at the University Hospital of Vienna from 1989 to 1996. Mycobacterium xenopi was found to be the second most common nontuberculous mycobacterial species (92 specimens from 30 patients) and was cultured predominantly from respiratory tract specimens. In 55% of patients, chest X-rays taken at the time of isolation demonstrated pathologic changes which could not be attributed to another cause. Therefore, according to our results, Mycobacterium xenopi should be viewed as an infectious agent rather than a contaminant in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1999

[Staging of bronchial carcinoma].

Staging of any tumor, i.e. determination of the extent of the disease, serves to select the patients who might profit from curative surgical intervention or to define those patients with inoperable carcinomas who should be referred for other therapies, such as chemotherapy or irradiation. Furthermore, accurate staging is necessary for assessment of prognosis, for radiation therapy planning, and for differentiation of those with small-cell lung cancer or for follow-up examinations of small-cell lung cancer patients after during and after chemotherapy. The primary radiological staging and diagnostic modalities for assessment of bronchial carcinomas are computed tomography (CT) of the thorax including liver and adrenal glands, abdominal sonography, and bone scintigraphy. Magnetic resonance imaging (MRI) should be reserved for specific indications, e.g. infiltration of the chest wall or staging of patients with intolerance/allergy to intravenous contrast medium. The clinical value of nuclear medicine techniques, such as [18F]2-fluoride-2-desoxy-D-glucose positron emission tomography (FDG-PET) for evaluation of lymph nodes and distant metastases, In-111 octreotide/somatostatin receptor scans for staging of small-cell lung cancer, and thallium-201 SPECT are currently being assessed in numerous studies, although these techniques are already in routine use. In future these or nuclear medicine techniques, as well as techniques using molecular-based contrast material, especially for MR imaging, currently in experimental status, may yield serious potential for staging purposes.

Carcinoma, Bronchogenic↗
PubMed1998

A dysfunctional desmin mutation in a patient with severe generalized myopathy.

Mice lacking desmin produce muscle fibers with Z disks and normal sarcomeric organization. However, the muscles are mechanically fragile and degenerate upon repeated contractions. We report here a human patient with severe generalized myopathy and aberrant intrasarcoplasmic accumulation of desmin intermediate filaments. Muscle tissue from this patient lacks the wild-type desmin allele and has a desmin gene mutation encoding a 7-aa deletion within the coiled-coil segment of the protein. We show that recombinant desmin harboring this deletion cannot form proper desmin intermediate filament networks in cultured cells, nor is it able to assemble into 10-nm filaments in vitro. These findings provide direct evidence that a mutation in desmin can cause human myopathies.

Amino Acid Sequence↗
PubMed1998

[Diagnostic imaging of the larynx. Normal anatomy of the regional spread of pathologic changes].

The primary goal of diagnostic imaging of the larynx is analysis of submucosal structures that are not visible by clinical or endoscopic means. Therefore, image analysis of the larynx should only be performed under knowledge of the results of clinical diagnosis. The anatomic relationships of the laryngeal skeleton, the intrinsic structures, and the surrounding soft tissue are presented synoptically.

Carcinoma, Squamous Cell↗
PubMed1998

[Postoperative complications after larynx resection: assessment with video-cinematography].

In past decades, the surgical techniques for treating laryngeal carcinoma have been vastly improved. For circumscribed tumors, voice-conserving resections are possible and for extensive neoplasms, radical laryngectomy, sometimes combined with chemoradiation, has been developed. Postoperative complications regarding swallowing function are not uncommon. Radiologic examinations, especially pharyngography and videofluoroscopy, are most often used to evaluate patients with complications after laryngeal surgery. An optimized videofluoroscopic technique for evaluation of complications is described. The radiologic appearance of early and late complications, such as fistulas, hematomas, aspiration, strictures, dysfunction of the pharyngoesophageal sphincter, tumor recurrence, and metachronous tumors is demonstrated.

Deglutition Disorders↗