Search PubMed⌕ Search

Biomedical subjects

M Heller

Publications and source records attributed to M Heller.

At least 199 records · Page 11Linked to original sources
PubMed1997

Kinematic MR imaging of the ankle--initial results with ultra-fast sequence imaging.

PURPOSE: In order to evaluate the advantages of ultra-fast MR sequences, kinematic MR imaging studies were performed in 4 patients with osteochondritis dissecans of the talus and in 12 healthy volunteers. MATERIAL AND METHODS: The patients and volunteers were placed inside a custom-made positioning device. Sagittal ultra-fast T2-weighted turbo gradient-echo sequences and HASTE sequences were obtained during active joint motion from dorsiflexion to plantar flexion. Eight sagittal slices were scanned separately to cover this ankle motion. In each slice, 8 to 10 images were obtained in 12-s or 18-s periods. RESULTS: Adequate image quality for analyzing the normal kinematics of the ankle was obtained in all subjects. At surgery, the osteochondral fragment was found to be mobile in 3 of the 4 of the patients. In none of these cases was fragment mobility observed on kinematic MR imaging. No motion of the fragments was observed in the fourth patient, neither at surgery nor on kinematic MR imaging. CONCLUSION: Ultra-fast MR imaging sequences made it possible to produce kinematic MR imaging studies of active joint motion. The positioning device was useful for guiding joint motion in patients and for obtaining adequate image quality.

Adult↗
PubMed1997

The total entropy for evaluating 31P-magnetic resonance spectra of the liver in healthy volunteers and patients with metastases.

RATIONALE AND OBJECTIVES: The authors describe the clinical status of liver tissue with only a single numerical quantity (total entropy) derived from spectroscopic data of 31P-magnetic resonance (MR) spectra. METHODS: Twenty-four patients with liver metastases and 20 volunteers were investigated with image-guided volume selective 31P-MR spectroscopy on a 1.5-T whole body scanner. From each in vivo 31P-MR spectrum, the ratios of phosphomonoester (PME)/beta-adenosine triphosphate (ATP), inorganic phosphate (Pi)/beta-ATP and phosphodiester (PDE)/ beta-ATP and the total entropy (H*) were calculated. Mean values and standard deviations were determined and significance of the differences were tested with Student's t test. RESULTS: For patients, the H* = 4.7 +/- 4.3, PME/beta-ATP 0.72 +/- 0.28, Pi/beta-ATP = 1.00 +/- 0.39, PDE/beta-ATP = 1.68 +/- 0.59. For the volunteers, H* = 7.6 +/- 2.5, PME/beta-ATP = 0.39 +/- 0.15, Pi/beta-ATP = 0.90 +/- 0.19, PDE/beta-ATP = 1.25 +/- 0.28. The total entropy of patients' spectra showed significantly lower values compared with those of volunteers. PME/beta-ATP and PDE/beta-ATP of the patients increased and differed significantly from volunteer data. CONCLUSIONS: It was demonstrated that the results of in vivo 31P-MR spectroscopy may be described with a single criterion by means of the total entropy.

Adenosine Triphosphate↗
PubMed1997

Rat amylin-(8-37) enhances insulin action and alters lipid metabolism in normal and insulin-resistant rats.

To clarify roles of amylin, we investigated metabolic responses to rat amylin-(8-37), a specific amylin antagonist, in normal and insulin-resistant, human growth hormone (hGH)-infused rats. Fasting conscious rats were infused with saline or hGH, each with and without amylin-(8-37) (0.125 mumol/h), over 5.75 h. At 3.75 h, a hyperinsulinemic (100 mU/l) clamp with bolus 2-deoxy-D-[3H]glucose and [14C]glucose was started. hGH infusion led to prompt (2- to 3-fold) basal hyperamylinemia (P < 0.02) and hyperinsulinemia. Amylin-(8-37) reduced plasma insulin (P < 0.001) and enhanced several measures of whole body and muscle insulin sensitivity (P < 0.05) in both saline- and hGH-infused rats. Amylin-(8-37) corrected hGH-induced liver insulin resistance, increased basal plasma triglycerides and lowered plasma nonesterified fatty acids in both groups, and reduced muscle triglyceride and total long-chain acyl-CoA content in saline-treated rats (P < 0.05). In isolated soleus muscle, amylin-(8-37) blocked amylin-induced inhibition of glycogen synthesis but had no effect in the absence of amylin. Thus 1) hyperamylinemia accompanies insulin resistance induced by hGH infusion; 2) amylin-(8-37) increases whole body and muscle insulin sensitivity and consistently reduces basal insulin levels in normal and hGH-induced insulin resistant rats; and 3) amylin-(8-37) elicits a significant alteration of in vivo lipid metabolism. These findings support a role of amylin in modulating insulin action and suggest that this could be mediated by effects on lipid metabolism.

Acyl Coenzyme A↗
PubMed1997

Computed tomography of the chest in diving-related pulmonary barotrauma.

Arterial gas embolism due to barotrauma of the lungs is a severe complication in compressed air diving. Precipitating factors are often missed on plain chest radiology. This study was conducted to detect occult lung disease predisposing to the development of pulmonary barotrauma in conditions associated with a change in ambient pressure. During the past 4 years, 11 patients who have suffered pulmonary barotrauma with or without subsequent development of cerebral or spinal arterial gas embolism underwent computed tomography of the chest several days post-injury. Examinations were conducted either using the conventional technique (n = 7) or, more recently, in the spiral mode (n = 4). Chest radiographs were available in all cases. In five patients CT revealed subpleural emphysematous blebs or cysts that were not detected by conventional radiography. Follow-up studies performed in two of these cases several months post-injury showed that the cystic lesions did not resolve. We assume that the lung cysts or blebs are preexisting conditions which caused pulmonary barotrauma. Computed tomography of the chest, preferably in the spiral mode, is recommended in any case of suspected pulmonary barotrauma in order to evaluate the possibility of pre-existing pathology and to predict future fitness to dive.

Adult↗
PubMed1997

Risk factors for pulmonary barotrauma in divers.

STUDY OBJECTIVES: Pulmonary barotrauma (PBT) of ascent is a feared complication in compressed air diving. Although certain respiratory conditions are thought to increase the risk of suffering PBT and thus should preclude diving, in most cases of PBT, risk factors are described as not being present. The purpose of our study was to evaluate factors that possibly cause PBT. DESIGN: We analyzed 15 consecutive cases of PBT with respect to dive factors, clinical and radiologic features, and lung function. They were compared with 15 cases of decompression sickness without PBT, which appeared in the same period. RESULTS: Clinical features of PBT were arterial gas embolism (n=13), mediastinal emphysema (n=1), and pneumothorax (n=1). CT of the chest (performed in 12 cases) revealed subpleural emphysematous blebs in 5 cases that were not detected in preinjury and postinjury chest radiographs. A comparison of predive lung function between groups showed significantly lower midexpiratory flow rates at 50% and 25% of vital capacity in PBT patients (p<0.05 and p<0.02, respectively). CONCLUSIONS: These results indicate that divers with preexisting small lung cysts and/or end-expiratory flow limitation may be at risk of PBT.

Adult↗
PubMed1997

Common carotid artery bifurcation: preliminary results of CT angiography and color-coded duplex sonography compared with digital subtraction angiography.

OBJECTIVE: The purpose of this study was to compare the abilities of color-coded duplex sonography, CT angiography, and selective digital subtraction angiography to reveal disease requiring surgery in patients with occlusive disease of the carotid bifurcation. MATERIALS AND METHODS: Fifty-six carotid arteries in 28 patients who had 48 carotid stenoses and symptomatic cerebrovascular disease were prospectively studied by selective digital subtraction angiography, color-coded duplex sonography, and CT angiography. CT data were displayed in maximum intensity projection. The degree of stenoses revealed were graded as mild, moderate, severe, and occluded according to North American Symptomatic Carotid Endarterectomy Trial criteria. The results of CT angiography and color-coded duplex sonography were correlated with the gold standard of digital subtraction angiography. RESULTS: Grading of stenoses on CT angiography agreed with grading of stenoses on digital subtraction angiography in 89% of cases. All high-grade stenoses and occlusions revealed on CT angiography were correctly interpreted by all observers. For stenoses revealed by color-coded duplex sonography and digital subtraction angiography, observers' agreement was 75%. Two severe stenoses were incorrectly graded as occluded by the interpreter of the color-coded duplex sonograms. Also, one occluded carotid artery was misdiagnosed as moderate stenosis. CONCLUSION: Our results indicate that CT angiography is superior to color-coded duplex sonography for evaluating carotid disease and determining disease requiring surgery. CT angiography warrants further investigation in a larger group of patients.

Angiography, Digital Subtraction↗
PubMed1997

MR imaging signal-intensity abnormalities after placement of arterial endoprostheses.

OBJECTIVE: Our objectives were to describe changes in T2-weighted MR images of patients who had undergone implantation of an endoluminal stent-graft and determine the rate of early reocclusion in patients with abnormal MR findings. SUBJECTS AND METHODS: Twenty-nine patients with 26 occlusions (average length, 8.7 +/- 5.6 cm) and three dissections of the superficial femoral artery were treated with 45 endoluminal stent-grafts. T2-weighted gradient-echo and T2-weighted turbo spin-echo MR images were obtained for all patients at 48 hr and at 4 weeks after stent-graft placement. We reviewed the MR imaging studies to assess the extent and severity of tissue alteration at the site of stent-graft implantation. RESULTS: Technical success rate of stent-graft placement was 100%. Three signal-intensity patterns were seen on MR images obtained at 48 hr: normal signal intensity (n = 8), subtle perivascular signal-intensity abnormalities at the site of stent-graft implantation (n = 11), and extensive signal-intensity abnormalities from the adductor canal to the subcutis (n = 10). Twenty of 21 patients with abnormal signal intensity on MR images had fevers and pain at the implantation site. Clinical signs of deep vein thrombosis, a diagnosis excluded on the basis of phlebography, were seen in the 10 patients with extensive signal-intensity abnormalities. In two of these 10 patients, the superficial femoral artery reoccluded within 4 weeks of implantation. MR images obtained at 4 weeks showed no signal-intensity abnormalities in any of the 29 patients. CONCLUSION: MR findings of perivascular signal-intensity abnormalities after implantation of endoluminal stent-grafts are associated with clinical complications such as local pain and fever. Care should be taken to avoid confusing the clinical signs of the postimplantation syndrome at 48 hr with deep vein thrombosis.

Aged↗
PubMed1997

Cardiac-gated two-dimensional phase-contrast MR angiography of lower extremity occlusive disease.

OBJECTIVE: The purpose of this study was to evaluate our capability to use coronally acquired, cardiac-gated two-dimensional phase-contrast MR angiography (MRA) to correctly detect and grade arteriosclerotic lesions from the aortic bifurcation to the popliteal artery. SUBJECTS AND METHODS: One hundred fifteen patients with a total of 253 arteriosclerotic lesions proven by intraarterial digital subtraction angiography were examined prospectively by two-dimensional phase-contrast MRA. MRA was performed from the aortic bifurcation to the popliteal trifurcation. Imaging parameters were TR/TE, 83/9 msec; flip angle, 11 degrees; matrix, 256 x 192; acquisitions, two; slice thickness, 80 mm; and field of view, 320 mm. ECG gating was used routinely and eight to 10 phases were acquired during the cardiac cycle. Velocity encoding was set to 30 cm/sec in the iliac arteries and to 20 cm/sec in the femoral and popliteal arteries. Detected stenoses were graded in the following manner: 1% to less than 50% stenosis, group 1; 50% to less than 75% stenosis, group 2; 75% to less than 100% stenosis, group 3; and total occlusion, group 4. RESULTS: All arteriosclerotic lesions were revealed by MRA. Two hundred seventeen of 253 lesions were also graded correctly. Sensitivity was 95%, specificity was 90%, positive predictive value was 90%, and negative predictive value was 96%. The weighted kappa index was (.92). Sensitivity and specificity for occlusions were both 100%; for high-grade stenoses, 94% and 91%, respectively; for moderate stenoses, 84% and 94%, respectively; and for mild stenoses, 79% and 100%, respectively. CONCLUSION: Two-dimensional phase-contrast MRA can provide MR angiograms with high sensitivity and specificity for high-grade stenoses in a reasonable amount of time in patients with peripheral artery occlusive disease.

Adult↗
PubMed1997

Drug-induced linear IgA disease: target antigens are heterogeneous.

No information is available concerning the target antigen(s) in drug-induced linear IgA disease. The purpose of this study was to define better drug-induced linear IgA disease by studying its immunopathological, immunoultrastructural and immunochemical characteristics in three patients. In the first patient, IgA deposits were seen in the lamina lucida. In the second and the third patients, IgA deposits were seen on each side of the lamina densa. Immunoblotting of the first patient's serum showed that IgA reacted with a protein of 230 kDa similar to the bullous pemphigoid-associated antigen 1 (BPAG 1). The second patient's serum did not react with specific bands. In the third patient IgA antibodies reacted with a protein of 97 kDa on epidermal extracts. Our findings suggest that, as in idiopathic forms, the target antigen is not unique in drug-induced linear IgA disease. In some patients, drug-induced linear IgA disease may represent an IgA class response to the BPAG 1.

Adult↗
PubMed1997

Epidermolysis bullosa acquisita in childhood.

BACKGROUND: Epidermolysis bullosa acquisita (EBA) is an autoimmune bullous disease characterized by the presence of antitype VII collagen antibodies, leading to the formation of bullae in the dermoepidermal junction. This disease is rare in childhood. OBSERVATIONS: We report 3 new cases of EBA in children. The 3 patients were similar; all 3 children were black, with a clinical phenotype resembling linear IgA bullous disease in children and typical histologic and immunologic features of EBA. In the 3 patients, diagnosis was proven using immune electron microscopy and Western blot analysis, where antitype VII collagen antibodies were demonstrated. Patients 1 and 2 were successfully treated with a combination of prednisone and dapsone. In patient 3, the lesions healed without specific therapy. We found 11 other pediatric cases of EBA in the literature and studied those cases in addition to the cases presented herein to describe the characteristics of EBA in childhood. CONCLUSIONS: Epidermolysis bullosa acquisita is a rare disease in childhood. Mucosal involvement is frequent and severe. Because the clinical features are misleading, the use of immune electron microscopy and Western blot analysis is essential to making a diagnosis. Treatment with a combination of prednisone and dapsone is often effective. The prognosis in children is better than it is in adult patients.

Adolescent↗
PubMed1997

[Minimal invasive therapy of aneurysms of the superficial femoral artery and the popliteal artery].

Percutaneous stent placement has been described for treatment of aneurysms as an alternative to surgical therapy. Literature reports of percutaneous minimal invasive therapy of peripheral aneurysms shall be reviewed and compared with our own results. Six male patients (51-69 years) with femoropopliteal occlusions related to aneurysms were treated percutaneously. In two cases Wallstents and in four cases polyester-covered nitinol stents were applicated. A clinical investigation including doppler-ultrasound was performed 24 hrs, 1, 3, 6, 12 and 24 months after the intervention. Stent placement succeeded in all cases. No adjunctive surgical treatment was necessary. Ankle-brachial-index (ABI) improved from 0.22 +/- 0.2 before to 0.74 +/- 0.2 24 hours after the intervention. One patient was lost for follow-up (Wallstent). A decrease of ABI and additional intraarterial angiography revealed stent-graft occlusion within one month (n = 2) and within three months (n = 1). One of these cases was successfully recanalized with local fibrinolysis therapy. In three patients patency of the stent persisted for 24 (+/- 2) months follow-up with three-vessel-supply of the calf. These results warrant further investigations for this minimal invasive method of percutaneous stent deployment as an alternative to surgical bypass treatment of femoropopliteal aneurysms. Time of hospitalization was reduced. At this time, surgical treatment of peripheral vascular aneurysms is gold standard.

Aged↗
PubMed1997

[Dura thickening adjacent to intracranial, para-dural space-occupying lesions in MRI. Histologic correlation].

PURPOSE: With intracranial tumors a flat, contrast-enhancing, probably dural structure adjacent to the tumor can occasionally be observed on gadolinium-DTPA enhanced MR images. Thers we have attempted to evaluate a tumor infiltration of these enhancement on MRI. MATERIAL AND METHODS: This study included 50 patients, 19 patients had a dural thickening at the tumor base (13 meningiomas and 6 metastases), while 31 patient did not (12 meningiomas and 19 metastases). Studies included plane T2-weighted spin echo (SE) images as well as T1-weighted axial, coronal, or sagittal plains with and without contrast agent. Histopathological examinations, were done on the tumor base adjacent to the dura mater. RESULTS: 7 of 12 meningiomas showed a meningeal thickening on MRI with histopathologically proven tumor infiltration as did also 5 of 6 metastases. But 3 of 12 meningiomas and 15 of 19 metastases without dural thickening at the tumor base also showed tumor invasion into the dura mater. CONCLUSION: MR imaging is still not able to determine whether or not there is a dural infiltration of the tumors base because there was no correlation between MR images and histopathologic results. In conclusion, metastases adjacent to the dura infiltrate the dura mater in a higher percentage than meningiomas.

Aged↗
PubMed1996

[Therapy of venous stenosis using wall stents].

OBJECTIVE: To evaluate the patency of Wallstents implanted for the treatment of venous stenoses in patients with benign or malignant disease. PATIENTS AND METHODS: 22 Wallstents (20 central venous; two peripheral) were implanted during a period of two years in 12 patients (nine men, three women; mean age 57.8 [26-76] years) with malignant venous stenoses (n = 9) or stenosed dialysis shunts (n = 3). Stent diameter ranged from 8-16 mm, length from 32-91 mm. Introduction of the stents were by percutaneous transfemoral catheterisation, in six patients with simultaneous wire placement from a cubital to the femoral vein. The superior vena cava was the involved vessel in six patients (in two each also the subclavian or brachiocephalic veins), in three only the subclavian vein, twice only the inferior vena cava and once the cephalic vein. RESULTS: The patency of the stents was checked after 4.7 +/- 3.6 (1-14) months, in seven patients clinically, by digital subtraction phlebography in three, by computed tomography in two. In nine patients there was no evidence of obstruction to flow or flow was normal. Stent occlusion had occurred in three patients, 4, 9 and 14 months after placement. There were no complications. Five patients died after a mean period of 4.8 +/- 3.6 (1-6.5) months from the underlying disease, without symptoms of obstruction to flow. CONCLUSION: Stent placement should be considered early, as it is a well-tolerated and effective palliative procedure for central venous stenoses associated with malignant disease or stenosis of dialysis shunts.

Adult↗
PubMed1996

Analysis of lipopolysaccharide-response genes in B-lineage cells demonstrates that they can have differentiation stage-restricted expression and contain SH2 domains.

Bacterial lipopolysaccharide (LPS) is a potent stimulator of B-cell activation, proliferation, and differentiation. We examined the genetic response of B-lineage cells to LPS via trapping of expressed genes with a gene-trap retrovirus. This analysis showed that expression of only a small fraction of genes is altered during LPS stimulation of B-lineage cells. Isolation of the cellular portion of the trapped LPS-response genes via 5' RACE (rapid amplification of cDNA ends) cloning identified novel genes for all the cloned loci. These novel LPS-response genes were also found to have differentiation stage-restricted expression within the B-lymphoid lineage. That LPS-response genes in B cells also have differentiation stage-restricted expression suggests that these genes may be involved in the control of B-cell function and differentiation, since the known members of this class of genes have frequently been found to play a role in the function and differentiation of B-lineage cells. The isolation of novel members of this class of genes, including a gene that contains a putative SH2 domain, will further increase our understanding of the molecular events involved in the control of B-cell differentiation and function.

Amino Acid Sequence↗
PubMed1996

Therapy for the maintenance of remission in sixty-five patients with generalized Wegener's granulomatosis. Methotrexate versus trimethoprim/sulfamethoxazole.

OBJECTIVE: To compare the efficacy of low-dose intravenous (IV) methotrexate (MTX; 0.3 mg/kg once weekly), both with and without concomitant prednisone, versus daily oral trimethoprim/sulfamethoxazole (T/S; 160 mg of trimethoprim + 800 mg of sulfamethoxazole twice a day), with and without prednisone, in maintaining remission in patients with generalized Wegener's granulomatosis (WG). METHODS: In this study, 65 patients with generalized WG whose disease had entered remission with cyclophosphamide (CYC) and prednisone therapy were started on one of the following remission-maintenance regimens: MTX alone (group A; n = 22), T/S alone (group B; n = 24), MTX plus concomitant prednisone (group C; n = 11), and T/S plus concomitant prednisone (group D; n = 8). Clinical, radiographic, and seroimmunologic data were evaluated to assess the efficacy of the 4 regimens and to seek possible predictive factors concerning outcome in each group. RESULTS: Partial or complete remission was maintained in 86% of the patients in group A, but in only 58% of those in group B (P < 0.05). In group C, 91% of patients remained in remission, which is in sharp contrast to group D, in which all patients experienced a relapse after a median of 14.5 months (P < 0.005). Side effects occurred twice as often with MTX (n = 12) as with T/S (n = 6) treatment and could usually be resolved by supplemental folinic acid. Two patients taking MTX and 3 patients taking T/S were withdrawn from the study medication because of side effects. In none of the patients were the adverse effects life threatening. No statistically significant factors predictive of poor outcome emerged in any group. CONCLUSION: Low-dose MTX was found to be superior to T/S for the safe and effective maintenance of remission in patients with generalized WG. The use of concomitant prednisone was not associated with a worse outcome with MTX treatment. Since T/S, especially with concomitant prednisone, seemed to increase the chance of relapse, neither T/S alone nor T/S plus prednisone can be recommended for the maintenance of remission in patients with generalized WG.

Adolescent↗
PubMed1996

Influence of different fasting periods on P-31-MR-spectroscopy of the liver in normals and patients with liver metastases.

The purpose of this study was to determine the influence of different fasting periods on the in vivo P-31-MR spectroscopy of the healthy liver and patients with liver metastases. Image-guided localized P-31-MRS was performed in 24 patients with liver metastases and in 20 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T using a surface coil. The P-31-MRS was performed after a fasting period of 3-5 h (group 1) and after overnight fasting (group 2). The PME/beta-NTP, PDE/beta-NTP and Pi/beta-NTP were calculated from P-31-MR spectra and were compared in relation to the nutrition status of the volunteers and patients. The PME/beta-NTP and PDE/beta-NTP were significantly increased in spectra of patients with metastases. There were no significant changes in the ratios of phosphorus metabolites in healthy liver tissue or in liver metastases after a fasting period of 3-5 h as compared with overnight fasting.

Adult↗