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Biomedical subjects

M Uhl

Publications and source records attributed to M Uhl.

At least 73 records · Page 4Linked to original sources
PubMed1999

Cystic medial degeneration of the aorta is associated with p53 accumulation, Bax upregulation, apoptotic cell death, and cell proliferation.

OBJECTIVE: To address a potential role for p53, Bcl2 associated protein X (Bax), and apoptosis in the processes associated with cell turnover during cystic medial degeneration (CMD) of the aorta. METHODS: Histochemical, immunohistochemical, biochemical, and morphometric methods were used to assess the presence and distribution of p53 immunoreactivity (p53-IR) and Bax immunoreactivity (Bax-IR), as well as the presence of apoptosis and tissue repair processes. RESULTS: Immunohistochemical staining disclosed evidence for p53-IR in all specimens in 26.1 (11.5)% of vascular smooth muscle cells (VSMCs) (controls 0.8 (1.3)%; p < 0. 001). Bax-IR was present in all specimens in 10 (5.4)% of medial cells (controls 0.3 (0.5)%; p < 0.001). Medial VSMCs (alpha-actin positive) with cytoplasmic staining for an apoptosis specific protein (c-jun/ASP) were present in 20/20 specimens (0.7 (0.6)% of VSMCs, controls 0%, p < 0.001), whereas terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL) positive VSMCs were present in 17/20 specimens (1 (1.5)% of VSMCs, controls 0%, p < 0.001). The presence of apoptosis was confirmed by electron microscopy and the demonstration of oligonucleosomal DNA fragments after agarose gel electrophoresis. As shown by double labeling and investigation of serial sections, p53-IR, Bax-IR, c-jun/ASP-IR, and positive TUNEL labeling localised to the same compartments of the aortic media, raising a possible role for p53 and Bax in the triggering of apoptosis of VSMC during CMD. MIB1/Ki-67 positive medial VSMCs (alpha-actin positive) and mesenchymal cells (vimentin positive) were present in all specimens (2.5 (2.8)% of medial cells; controls 0.3 (0.9)%, p < 0.001) mainly in the region around the vasa vasorum, indicating that cell regeneration during CMD may originate mainly from the mesenchyme surrounding the vasa vasorum. CONCLUSION: This study shows that the formal pathogenesis of CMD is characterised by p53 accumulation, Bax upregulation, cell death by apoptosis, and cell regeneration. Nevertheless, the precise stimuli of p53 activation and Bax upregulation as well as the role of p53 and apoptosis in the dissection process itself remain elusive.

Adult↗
PubMed1999

Rare-MR-urography--a new diagnostic method in autosomal recessive polycystic kidney disease.

PURPOSE: To describe the appearance of autosomal recessive polycystic kidney disease (ARPKD) by using a new diagnostic method: RARE-MR-urography. MATERIAL AND METHODS: Eight children were evaluated using MR images from 0.23 T and 1.5 T MR units, using T1-weighted spin-echo and T2-weighted turbo spin-echo sequences and RARE-MR-urography. Signal intensities, morphological appearance of the affected kidneys and, specifically, the picture of the urinary tract in RARE-MR-urography, were evaluated. RESULTS: All children showed enlargement, reniform but humpy kidney shape, homogeneous-grainy renal parenchyma, normal renal pelvis and calyces. Although ARPKD is always associated with some degree of congenital hepatic fibrosis, there was no bile duct dilatation or liver fibrosis at the time of examination. Signal intensity was hyperintense in T2-weighted images in all cases. In 5 cases, T1-weighted images were hypointense. In RARE-MR-urography, hyperintense, linear, radial patterns in cortex and medulla were seen, which represent microcystic dilatation of collecting ducts and are therefore characteristic of ARPKD. Four patients presented with a few circumscribed small subcapsular cysts. CONCLUSION: RARE-MR-urography is a noninvasive method which demonstrates the pathognomonic water-filled cystic structures throughout the kindeys in ARPKD.

Adolescent↗
PubMed1998

Use of metabolically competent human hepatoma cells for the detection of mutagens and antimutagens.

The human hepatoma line (Hep G2) has retained the activities of various phase I and phase II enzymes which play a crucial role in the activation/detoxification of genotoxic procarcinogens and reflect the metabolism of such compounds in vivo better than experimental models with metabolically incompetent cells and exogenous activation mixtures. In the last years, methodologies have been developed which enable the detection of genotoxic effects in Hep G2 cells. Appropriate endpoints are the induction of 6-TGr mutants, of micronuclei and of comets (single cell gel electrophoresis assay). It has been demonstrated that various classes of environmental carcinogens such as nitrosamines, aflatoxins, aromatic and heterocyclic amines and polycyclic aromatic hydrocarbons can be detected in genotoxicity assays with Hep G2 cells. Furthermore, it has been shown that these assays can distinguish between structurally related carcinogens and non-carcinogens, and positive results have been obtained with rodent carcinogens (such as safrole and hexamethylphosphoramide) which give false negative results in conventional in vitro assays with rat liver homogenates. Hep G2 cells have also been used in antimutagenicity studies and can identify mechanisms not detected in conventional in vitro systems such as induction of detoxifying enzymes, inactivation of endogenously formed DNA-reactive metabolites and intracellular inhibition of activating enzymes.

Animals↗
PubMed1998

MR findings in pontocerebellar hypoplasia.

We present four cases with combined hypoplasia of the cerebellum and the ventral pons-pontocerebellar hypoplasia (PCH). PCH represents an autosomal recessive neurodegenerative disorder with fetal onset. The disease is rare, with less than 20 cases having been reported. The main findings of PCH and the inclusion criteria for our cases can be summarised as progressive microcephaly from birth, pontocerebellar hypoplasia documented by MRI and marked chorea, which may change, later in childhood, to more dystonic patterns. The cerebral cortex becomes progressively atrophic. Motor and mental development are delayed, and epilepsy, mainly tonic-clonic seizures, is frequent. The MRI features in all of our cases were: (1) Hypoplastic cerebellum situated close to the tentorium. The hypoplastic cerebellum has a reduced number of folia, in contrast to the normal number of thin folia in simple cerebellar atrophy. (2) The cerebellar hemispheres are reduced to bean-like or wing-like structures. The cerebellar hemispheres appear to 'float' in the posterior fossa. (3) Markedly hypoplastic ventral pons. (4) Slight atrophy of the supratentorial gyral pattern. (5) Dilated cerebromedullary cistern and fourth ventricle. (6) Delayed myelination of the white matter. (7) No significant disorganisation of brain architecture and no severe corpus callosum defect.

Cerebellum↗
PubMed1998

Comparison of turbo inversion recovery magnitude (TIRM) with T2-weighted turbo spin-echo and T1-weighted spin-echo MR imaging in the early diagnosis of acute osteomyelitis in children.

OBJECTIVE: To compare turbo inversion recovery magnitude (TIRM) with standard T1-weighted (T1-W) and T2-weighted (T2-W) MR sequences in the very early detection of acute osteomyelitis in children. MATERIALS AND METHODS: In 15 children with osteomyelitis, 15 sets of T1-W spin-echo (SE) (TR/TE, 400-640/12-17), T2-W turbo spin-echo (TSE) (TR/TE/ETL, 3290-4465/112-120/11), and TIRM (TR/TE/TI, 4000-6120/60/160) images were acquired with a 1.0-T magnet. Contrast-to-noise (C/N) ratios and percentage of signal between lesion and normal bone marrow were analysed with a computer-assisted image analysing system in a region of interest (ROI). RESULTS: In 13 of 15 patients, the absolute signal enhancement in a ROI on the TIRM images was better than on the T1-W SE and T2-W TSE images and in 14 of 15 cases, C/N ratios were also better on the TIRM images than on the other sequences. In the other cases, the TIRM signal was diagnostically equivalent. On the TIRM images, the signal difference between normal and pathological tissue was increased to 43-281% (mean 124%). On the T2-W TSE images, this signal difference was 4-79% (mean 36%) and on the T1-W SE images 6-77% (mean 37%). Conclusion. The TIRM sequence is highly sensitive for detecting bone marrow oedema in the very early stage of acute osteomyelitis in children. MRI utilising the TIRM sequence allowed for an early diagnosis. With scan time of less than 4 minutes, this sequence is superior to T1-W SE and T2-W TSE images for detecting early osteomyelitis-associated bone marrow oedema.

Acute Disease↗
PubMed1998

Cartilage destruction in small joints by rheumatoid arthritis: assessment of fat-suppressed three-dimensional gradient-echo MR pulse sequences in vitro.

PURPOSE: To assess the accuracy of different MR sequences for the detection of articular cartilage abnormalities in rheumatoid arthritis. DESIGN AND PATIENTS: Ten metacarpophalangeal joints and 10 metatarsophalangeal joints (specimens from arthritis patients undergoing ablative joint surgery) were examined with a fat-suppressed (FS) 3D FLASH, a FS 3D FISP, a FS 2D fast spin-echo T2-weighted, and a 2D FS spin-echo T1-weighted sequence. Each cartilage lesion and each cortical lesion was graded from 0 to 4 (modified Outerbridge staging system). Subsequently, the results of each sequence were compared with the macroscopic findings and statistically tested against each other. RESULTS: The study shows that 3D gradient-echo sequences with fat suppression were best for imaging and grading of cartilage lesions in arthritis of the small joints of the hands and feet. Using 3D techniques, all grade 2, grade 3, and grade 4 lesions of cartilage or cortical bone were detected. CONCLUSION: FS 3D gradient-echo techniques were best for the detection and grading of hyaline cartilage and subchondral bone lesions in rheumatoid arthritis. MRI has a great potential as an objective method of evaluating cartilage damage and bone erosions in rheumatoid arthritis.

Adipose Tissue↗
PubMed1998

Diagnosis of idiopathic myositis: value of 99mtechnetium pyrophosphate muscle scintigraphy and magnetic resonance imaging in targeted muscle biopsy.

Our objective was to study the value of 99mtechnetium-pyrophosphate (99mTc-PYP) muscle scintigraphy and magnetic resonance imaging (MRI) in detecting areas of likely muscle inflammation and in increasing the rate of positive muscle biopsies in patients with suspected myositis. The results showed that in 13 out of 13 patients with clinical and/or signs of inflammatory muscle disease, increased 99mTc-PYP uptake was demonstrated at different muscle sites 3 h after isotope injection. Subsequent MRI of symmetric muscle areas with enhanced 99mTc-PYP uptake revealed signal patterns suggesting inflammation in all cases. Biopsy of these targeted muscles demonstrated characteristic histopathologic signs of muscle inflammation in 9 out of 13 patients. Four of these 9 patients had clinically atypical disease or did not show elevated creatine phosphokinase levels. Seven of these 9 patients had not been pretreated with corticosteroids. In 4 patients only muscle fiber atrophy and/or necrosis without cellular infiltrations was seen. These 4 patients had received either high doses of corticosteroids or low doses over longer periods of time before muscle biopsy. In conclusion, the combination of 99mTc-PYP muscle scintigraphy and MRI demonstrated muscle areas with maximum inflammatory signal patterns. Targeting of muscles by MRI only will probably yield reliable results of muscle biopsy in cases of clinically and serologically characteristic myositis. 99mTc-PYP muscle scintigraphy may provide useful initial information about localization of inflamed muscle tissue, especially in atypical disease. Treatment with corticosteroids prior to histologic diagnosis may abolish inflammatory infiltrations in affected muscle tissue.

Adolescent↗
PubMed1998

A mild form of Proteus syndrome.

Proteus syndrome is a rare congenital hamartomatous syndrome. We report on the clinical and radiological appearances of a boy in order to illustrate the typical signs which include subcutaneous masses, in mild forms partial gigantism of hands and feet, hemihypertrophy, and bony abnormalities. We discuss how to make the definitive diagnosis on the basis of using a known rating scale, important aspects of differential diagnosis and clinical features, and diagnostic management.

Child, Preschool↗
PubMed1998

Human articular cartilage: in vitro correlation of MRI and histologic findings.

The aim of our study was to correlate MRI with histologic findings in normal and degenerative cartilage. Twenty-two human knees derived from patients undergoing amputation were examined with 1.0- and 1. 5-T MR imaging units. Firstly, we optimized two fat-suppressed 3D gradient-echo sequences. In this pilot study two knees were examined with fast imaging with steady precession (FISP) sequences and fast low-angle shot (FLASH, SPGR) sequence by varying the flip angles (40, 60, 90 degrees) and combining each flip angle with different echo time (7, 10 or 11, 20 ms). We chose the sequences with the best visual contrast between the cartilage layers and the best measured contrast-to-noise ratio between cartilage and bone marrow. Therefore, we used a 3D FLASH fat-saturated sequence (TR/TE/flip angle = 50/11 ms/40 degrees) and a 3D FISP fat-saturated sequence (TR/TE/flip angle = 40/10 ms/40 degrees) for cartilage imaging in 22 human knees. The images were obtained at various angles of the patellar cartilage in relation to the main magnetic field (0, 55, 90 degrees). The MR appearances were classified into five categories: normal, intracartilaginous signal changes, diffuse thinning (cartilage thickness < 3 mm), superficial erosions, and cartilage ulcers. After imaging, the knees were examined macroscopically and photographed. In addition, we performed histologic studies using light microscopy with several different stainings, polarization, and dark field microscopy as well as electron microscopy. The structural characteristics with the cartilage lesions were correlated with the MR findings. We identified a hyperintense superficial zone in the MR image which did not correlate to the histologically identifiable superficial zone. The second lamina was hypointense on MRI and correlated to the bulk of the radial zone. The third (or deep) cartilage lamina in the MR image seemed to represent the combination of the lowest portion of the radial zone and the calcified cartilage. The width of the hypointense second zone correlated weakly to the accumulation of proteoglycans in the radial zone. The trilaminar MRI appearance of the cartilage was only visible when the cartilage was thicker than 2 mm. In cartilage degeneration, we found either a diffuse thinning of all layers or circumscribed lesions ("cartilage ulcer") of these cartilage layers in the MR images. Early cartilage degeneration was indicated by a signal loss in the superficial zone, correlating to the histologically proven damage of proteoglycans in the transitional and radial zone along with destruction of the superficial zone. We found a strong effect of cartilage rotation in the main magnetic field, too. A rotation of the cartilage structures caused considerable variation in the signal intensity of the second lamina. Cartilage segments in a 55 degreesangle to the magnetic main field had a homogeneous appearance, not a trilaminar appearance. The signal behavior of hyaline articular cartilage does not reflect the laminar histologic structure. Osteoarthrosis and cartilage degeneration are visible on MR images as intracartilaginous signal changes, superficial erosions, diffuse cartilage thinning, and cartilage ulceration.

Aged↗
PubMed1998

Functional MR imaging of the cervical spine in patients with rheumatoid arthritis.

PURPOSE: To evaluate functional MR imaging in patients with rheumatoid arthritis (RA) involving the cervical spine. MATERIAL AND METHODS: We used a device that allows MR examination to be made of the cervical spine in infinitely variable degrees of flexion and extension. Dynamic functional MR imaging was performed on 25 patients with RA. RESULTS: Functional MR imaging was able to show the degree of vertebral instability of the occipito-atlantal or atlanto-axial level as well as the subaxial level. By performing functional MR imaging, we were able to demonstrate the extent of synovial tissue around the dens, and the impingement and displacement of the spinal cord during flexion and extension. The basilar impression, the cord impingement into the foramen magnum, the cord compression, the slipping of vertebrae, and the angulation of the cord were all much more evident in functional than in static MR imaging. CONCLUSION: Functional MR imaging provided additional information in patients with RA, and is valuable in patients who have a normal MR study in the neutral position and yet have signs of a neurological deficit. Functional MR imaging is important in the planning of stabilizing operations of the cervical spine.

Adult↗
PubMed1998

Successful treatment of gastrointestinal vasculitis due to systemic lupus erythematosus with intravenous pulse cyclophosphamide: a clinical case report and review of the literature.

Gastrointestinal vasculitis in systemic lupus erythematosus (SLE) is quite rare and almost always accompanied by evidence of active disease in other organs, although occasionally it may be the presenting feature of the disease. Gastrointestinal involvement in SLE may present as lupus peritonitis, non-necrotizing pancreatitis, gastrointestinal vasculitis or surgical abdomen. Here we report a severe case of SLE which presented initially with fever of unknown origin. Severe distress, abdominal pain, the presence of occult blood in the stool and high acute-phase proteins were explained by a lupus peritonitis and intestinal vasculitis resembling inflammatory bowel disease. Whereas high-dose prednisone treatment did not prevent a severe relapse, we observed a sustained remission following i.v. cyclophosphamide pulse therapy. In the literature, only two similar cases are reported: one died despite a change in the therapy of a bowel perforation; our case was the second that improved under pulse cyclophosphamide. We suggest the use of cyclophosphamide after failure of steroids early in the course of SLE gastrointestinal vasculitis to prevent devastating complications.

Abdominal Pain↗
PubMed1998

Magnetic resonance diagnosis of the anterior labrum and capsule. Effect of field strength on efficacy.

RATIONALE AND OBJECTIVES: The authors compare the performance of high-field and low-field magnetic resonance (MR) systems in the evaluation of shoulder instability, 35 patients were examined at field strengths of 1.0 T and of 0.2 T. METHODS: Surface coils were used in both systems. Because arthroscopy was used as gold standard, a preselected patient-population was obtained for the study. RESULTS: The sensitivity/specificity/accuracy of MR images acquired at 1.0 T for labrum pathology were 91%/67%/91% and 70%/80%/71% for the capsular complex. Compared with the above, the sensitivity/specificity/accuracy for 0.2 T MR images revealed 91%/67%/91% for the labrum pathology and 63%/80%/66% for the capsular complex respectively. In the evaluation of capsular lesions a comparison between the 0.2 T MR system and the 1.0 T system indicated a higher sensitivity and accuracy for the high-field images. Concerning labral lesions, the sensitivity and accuracy of the 0.2 T MR imager and the 1.0 T imager were comparable. CONCLUSIONS: Given differences in imaging protocols, imaging at 0.2 T does not adversely affect the assessment of shoulder instability when compared with imaging at 1.0 T. These preliminary results warrant more extensive clinical comparison of results obtained at different magnetic field strengths.

Adolescent↗
PubMed1998

Comparison of MR sequences in quantifying in vitro cartilage degeneration in osteoarthritis of the knee.

Magnetic resonance imaging of amputated human knees was performed to determine optimal sequences for depicting articular cartilage. 24 knees were examined with eight different sequences in a 1.0 T imager. Each cartilage lesion was graded from 1 to 4 (Outerbridge staging system). The results of each sequence were compared with the macroscopic findings and statistically tested against each other. The FLASH sequence (TR = 50 ms) with combination of flip angle of 40 degrees and echo time of 10 ms and the FISP sequence (TR = 40 ms) with combination of flip angle of 40 degrees and echo time of 11 ms were best for depicting cartilage structure and internal detail. There was no significant difference between fat-saturated three-dimensional FLASH (FS-3D-FLASH) and FS-3D-FISP (p = 0.05). These FS-3D sequences were significantly better than sequences without fat saturation (p = 0.05). There was no significant difference between magnetization transfer (MT) 3D-FLASH, MT-3D-FISP and 3D-FISP. All 3D sequences showed significantly (p = 0.05) better results than spin echo or fast spin echo sequences. The T1 weighted SE pulse sequence was significantly (p = 0.005) better than the T2 weighted TSE sequence. Fast T2 weighted spin echo was not suitable for early and accurate detection of cartilage lesions.

Aged↗
PubMed1998

[Recent developments and applications of MRI sequence technique. I: turbo spin echo, HASTE, turbo inversion recovery, turbo gradient echo, turbo gradient spin sequences].

Goal of this two-part report is to provide clinical MRI radiologists with a guide to the world of new and clinically available MRI pulse sequences. Discussed are the principles of rapid scan techniques like multiple spin-echo imaging, multiple gradient echo imaging, echo planar imaging, diffusion and perfusion imaging, and future perspectives (review article).

Echo-Planar Imaging↗
PubMed1997

Determination of drugs in hair using GC/MS/MS.

An important task for the forensic toxicologist and expert witness is the detection of the noxa in biological matrices. Because of this, the identification and quantification of residues of illegal drugs in human hair is still of growing interest. Utilizing the advantages of GC/MS/MS testing human hair is performed for most common drugs of abuse like heroin and other opioides, cocaine, cannabis and amphetamine derivatives. Analyzing hair specimens for substances that present a toxicological risk is another challenge. Several quality control parameters must be observed to avoid false positive or false negative results and to gain additional information. Blank sample, blank hair as well as the combined wash extracts are tested for the presence of the relevant compounds within every series. Careful evaluation of the findings can provide an approximate measure of the intensity of drug use in the majority of cases.

Adult↗
PubMed1997

MR imaging of the carpal tunnel.

OBJECTIVE: Investigations were conducted regarding changes of carpal tunnel shape during wrist motion and the variations of space for the median nerve as well as the preoperative signs of carpal tunnel syndrome (CTS) and the postoperative restitution. METHODS: Axial MR images (1.0 T) were performed at the level of the distal radioulnar joint, pisiforme bone and hook of hamate level of 20 wrists of patients with clinical symptoms of CTS and further 20 wrists of volunteers. This was conducted with the wrist in neutral position, 45 degrees extension and 45 degrees flexion. T2-weighted signal intensity of the median nerve were measured in 18 patients pre- and postoperatively. RESULTS: The increase of the cross-sectional area of the median nerve at the pisiform level and the flattening of the median nerve at the hook of hamate level as well as the volar bowing of the flexor retinaculum at the pisiform and hook of hamate level were significantly greater in patients with CTS than in those with normal wrists (P < 0.05-0.001). In postoperative follow-up studies the distal flattening of the median nerve recovered in 94%. The signal intensity of the median nerve on T2-weighted images decreased in 67%. CONCLUSIONS: Flexion at the pisiform and hamate level as well as extension at the pisiform level narrows the space available for the median nerve potential leading to compression of the median nerve. MR imaging is accurate and reliable for diagnosis and postoperative follow-up of CTS.

Adult↗
PubMed1997

Diagnosis of thromboembolic disease during infancy and childhood.

Thromboembolic disorders are frequent complications in pediatric patients and the incidence seems to rise. Adult guidelines for thromboembolism do not hold for children because there are many age-related features. Congenital prethrombotic disorders play a major role in the pediatric population and activated protein C (APC) resistance is also the most frequently encountered problem. Acquired risk factors in children are central venous line thrombosis with serious complications, cardiac diseases such as cardiomyopathies, prosthetic heart valves and aneurysms, renal vein thrombosis, and nephrotic syndrome. Renal vein thrombosis primarily affects newborns. Children with the antiphospholipid antibody syndrome also have thromboses although less frequent than adults, but systemic lupus erythematosus is associated with a high incidence. Acute lymphoblastic leukemia is frequently associated with thrombosis in children, especially when complicated by APC resistance. The greatest risk of thrombosis in children is during the neonatal period, and again congenital prethrombotic states and catheter placement play a major role. The clinical manifestations in children reflect the site of the thrombosis and extensive laboratory evaluations and advanced diagnostic procedures must be employed to diagnose the thrombotic events.

Adolescent↗