Search PubMed⌕ Search

Biomedical subjects

M Heller

Publications and source records attributed to M Heller.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Mechanical brush-catheter abrasion method for the isolation and culture of human umbilical vein endothelial cells. First in vitro results].

UNLABELLED: Mechanical brush-catheter abrasion method for the isolation and culture of human umbilical vein endothelial cells. First in vitro results. PURPOSE: To determine the value of a nylon brush (Cragg thrombolytic catheter system) with regard to the isolation and culture of viable human vascular umbilical vein endothelial cells (HUVEC). MATERIAL AND METHODS: Fresh human umbilical cords were collected after a maximum of 6 - 8 h post delivery. They were stored in sterile tubes till further preparation. After predilation the umbilical cord veins, a 6 French brush catheter was inserted, expanded, and removed by hand using rotating movements. The nylon brush was shaken out in cell medium containing serum proteins by a connected motor drive. After repeating these procedures, the detached endothelial cells were centrifugated and resuspended. The cell numbers were assessed and cell viability controlled. RESULTS: The endothelial cell (EC) viability depended on the umbilical cord's age and was the highest (29.8 +/- 11.4 %) within 3 h after delivery. The brush abrasion (3.32 x 10(5) +/- 52016 viable EC/10 cm vein segment) enabled us to culture these cells under different cell concentrations. They grew to confluence after 2 - 3 weeks. CONCLUSIONS: The brush-catheter abrasion is an effective method for collecting viable human endothelial cells in vitro.

Catheterization, Peripheral↗
PubMed2001

Comparison of the mechanical thrombectomy efficacy of the Amplatz thrombectomy device and the Cragg thrombolytic brush in vitro.

RATIONALE AND OBJECTIVES: To determine the efficacy of thrombectomy (without thrombolytic agents) for the Amplatz thrombectomy device (ATD) and the Cragg thrombolytic brush catheter (CBC) in vitro. METHODS: Thrombectomy was performed with the ATD or CBC (6F) in a flow model. Embolus sizes, weight, remaining thrombus, and activation time were evaluated. RESULTS: No significant difference in the activation time was found. The CBC produced significantly less embolism (3.3% vs. 0.03% in the 5-mm and 89% vs. 0.5% in the 7-mm model), but also much more thrombus remained in the system than with the ATD (1% vs. 41% in the 5-mm and 0.1% vs. 62% in the 7-mm model). CONCLUSIONS: The ATD can remove almost all thrombus (99%), whereas the CBC removes only up to 60%, producing fewer emboli than the ATD. This might be due to the lower rotational speed of the CBC compared with the ATD, which is 20 times greater. The soft nylon brush offers less resistance and shear force toward the thrombus than the stainless-steel impeller of the ATD. Because of the large amount of remaining thrombus, the CBC should not be used without lytic agents.

Catheterization↗
PubMed2001

Mechanical thrombectomy of major and massive pulmonary embolism with use of the Amplatz thrombectomy device.

RATIONALE AND OBJECTIVES: To evaluate the feasibility of mechanical thrombectomy with the Amplatz thrombectomy device (ATD) in restoring patency of acutely thrombosed pulmonary arteries resulting from pulmonary embolism for the improvement of patient outcome. METHODS: Mechanical thrombectomy with the ATD (8F) was performed in nine consecutive patients with angiographically documented thrombus in the left or right pulmonary artery resulting from deep vein thrombosis (n = 4) or unknown cause (n = 5). RESULTS: The Miller index decreased from 18 to 11. In all patients, the majority of the thrombus in the pulmonary artery was cleared after a mean activation time of the ATD of 367 seconds. Thrombectomy was performed with the ATD alone (n = 4) or with additional long-term fibrinolysis therapy (n = 5) with infusion of recombinant tissue-type plasminogen activator. Pulmonary arterial pressure decreased from a mean of 57 mm Hg before mechanical thrombectomy to 55 mm Hg directly after the procedure and to 39 mm Hg after termination of the recombinant tissue-type plasminogen activator infusion. CONCLUSIONS: Mechanical thrombectomy with the ATD in patients with minor and major pulmonary embolism is technically feasible and safe. It is a potential alternative to drug-mediated thrombolysis and surgery. However, the incremental benefit of the ATD over conventional treatments could be shown only in a randomized controlled study.

Acute Disease↗
PubMed2001

Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes?

OBJECTIVE: To measure the ability of cardiac sonography and capnography to predict survival of cardiac arrest patients in the emergency department (ED). METHODS: Nonconsecutive cardiac arrest patients prospectively underwent either cardiac ultrasonography alone or in conjunction with capnography during cardiopulmonary resuscitation at two community hospital EDs with emergency medicine residency programs. Cardiac ultrasonography was carried out using the subxiphoid view during pauses for central pulse evaluation and end-tidal carbon dioxide (ETCO(2)) levels were monitored by a mainstream capnograph. A post-resuscitation data collection form was completed by each of the participating clinicians in order to assess their impressions of the facility of performance and benefit of cardiac sonography during nontraumatic cardiac resuscitation. RESULTS: One hundred two patients were enrolled over a 12-month period. All patients underwent cardiac sonographic evaluation, ranging from one to five scans, during the cardiac resuscitation. Fifty-three patients also had capnography measurements recorded. The presence of sonographically identified cardiac activity at any point during the resuscitation was associated with survival to hospital admission, 11/41 or 27%, in contrast to those without cardiac activity, 2/61 or 3% (p < 0.001). Higher median ETCO(2) levels, 35 torr, were associated with improved chances of survival than the median ETCO(2) levels for nonsurvivors, 13.7 torr (p < 0.01). The multivariate logistic regression model, which evaluated the combination of cardiac ultrasonography and capnography, was able to correctly classify 92.4% of the subjects; however, of the two diagnostic tests, only capnography was a significant predictor of survival. The stepwise logistic regression model, summarized by the area under the receiver operator curve of 0.9, furthermore demonstrated that capnography is an outstanding predictor of survival. CONCLUSIONS: Both the sonographic detection of cardiac activity and ETCO(2) levels higher than 16 torr were significantly associated with survival from ED resuscitation; however, logistic regression analysis demonstrated that prediction of survival using capnography was not enhanced by the addition of cardiac sonography.

Capnography↗
PubMed2001

Assessment of phalangeal bone loss in patients with rheumatoid arthritis by quantitative ultrasound.

OBJECTIVE: Periarticular osteopenia is an early radiological sign of rheumatoid arthritis (RA). Quantitative ultrasound (QUS) devices have recently been shown to be useful for assessing osteoporosis. In this study the capability of a transportable and easy to use QUS device to detect skeletal impairment of the finger phalanges in patients with RA was investigated. METHODS: In a cross sectional study 83 women (30 controls, 29 with glucocorticosteroid (GC) treated RA, and 24 with GC treated vasculitis) were examined. QUS measurements were obtained at the metaphyses of the proximal phalanges II-V and directly at the proximal interphalangeal joints II-IV with a DBM Sonic 1200 (IGEA, Italy) QUS device. Amplitude dependent speed of sound (AD-SoS) was evaluated. In 23 of the patients with RA, hand radiographs were evaluated. RESULTS: Significant differences between patients with RA and the other groups were found for AD-SoS at both measurement sites. Compared with age matched controls, the AD-SoS of patients with RA was lowered by two and three standard deviations at the metaphysis and joint, respectively. Fingers of patients with RA without erosions (Larsen score 0-I) already had significantly decreased QUS values, which deteriorated further with the development of erosions (Larsen II-V). CONCLUSION: This study indicates that QUS is sensitive to phalangeal periarticular bone loss in RA. QUS is a quick, simple, and inexpensive method free of ionising radiation that appears to be suited to detection of early stages of periarticular bone loss. Its clinical use in the assessment of early RA should be further evaluated in prospective studies.

Adult↗
PubMed2001

[Evaluating the stability of fracture fixation systems: mechanical device for evaluation of 3-D stiffness in vitro].

Different fixation systems are used for fracture and defect treatment. A prerequisite for complication free healing is sufficient mechanical stability of the osteosynthesis. In vitro investigations offer the possibility of both analysing and assessing the pre-clinical fixation stability. Due to the complex loading environment in vivo, stiffness analysis should include a complete determination of the stiffness under standardised conditions. Based on a mathematical procedure to calculate the 3-D stiffness, a mechanical testing device for the 3-D loading of fixation systems was designed and integrated in the existing test set-up. The set-up consisted of a material testing machine to produce the necessary loads and an optical measurement device to detect the resulting inter-fragmentary movements. To validate the testing device, the 3-D stiffness matrices of different Ilizarov fixator configurations were determined and compared. The good reproducibility of the test was reflected in the small intra-individual variability of the stiffness components. A distinct direction dependence of the fixator stiffness was observed. Increasing the number of rings led to a stiffness increase of up to 50%, especially in bending. The presented testing device allows a complete standardised determination of the stiffness of different fixation systems. It considers the direction dependence of the stiffness and creates a prerequisite for a more direct implant comparison.

Biomechanical Phenomena↗
PubMed2000

Stille-type cross-coupling-An efficient way to various symmetrically and unsymmetrically substituted methyl-bipyridines: toward new ATRP catalysts

Various mono- and disubstituted 2,2'-bipyridines were synthesized in high yields and multigram scales utilizing Stille-type coupling procedures. The corresponding bromo-picoline and tributyltin-picoline building blocks were prepared from commercially available amino-picoline compounds. As first examples of metal complexes, 4,5'-dimethyl-2,2'-bipyridine was reacted with copper(II) and iron(II) ions and investigated as catalyst in ATRP.

Journal Article↗
PubMed2000

Synthesis of biologically active tritiated amylin and salmon calcitonin analogues.

Amylin is a hormone belonging to the calcitonin protein family of peptides. To facilitate receptor screening studies, alternatively radiolabeled and biologically active amylin and salmon calcitonin analogues were synthesized by reductive methylation. Free amino groups of amylin and salmon calcitonin were methylated by reaction of peptides with formaldehyde and sodium [(3)H]borohydride. Radioactively labeled peptides were purified by size exclusion chromatography followed by HPLC. Analysis by MALDI-TOF mass spectrometry of purified amylin and salmon calcitonin peptides revealed incorporation of both two and four tritiated methyl groups per peptide molecule. Specific activities of 22.6 and 23.2 GBq/mmol were measured for amylin and salmon calcitonin, respectively. Methylation of rat amylin and salmon calcitonin did not affect their biological activities as both retained their potency to inhibit insulin-stimulated glycogen synthesis in isolated rat soleus muscle. The synthesis of these tritiated analogues provides an alternative chemically stable radiolabeled ligand which may be useful in exploring receptor interactions within the calcitonin peptide family.

Amyloid↗
PubMed2000

Activation of insulin-like growth factor I receptor signaling pathway is critical for mouse plasma cell tumor growth.

Plasma cell neoplasia in humans generally occurs as multiple myeloma, an incurable form of cancer. Tumors with marked similarity can be induced in mice by a variety of agents, including chemicals, silicone, and oncogene-containing retroviruses, suggesting the use of murine tumors as an informative model to study plasma cell disease. Herein, we have focused on the role of insulin-like growth factor I receptor (IGF-IR) signaling in the development of plasma cell disease. The insulin receptor substrate 2/phosphatidylinositol 3'-kinase/p70S6K pathway was found to be either constitutively or IGF-I-dependently activated in all plasma cell tumors. Biological relevance was demonstrated in that plasma cell lines with up-regulated IGF-IR expression levels exhibited mitogenic responses to IGF-I. More importantly, expression of a dominant-negative mutant of IGF-IR in these lines strongly suppressed tumorigenesis in vivo. Taken together, these results demonstrate that up-regulation and activation of IGF-IR and the downstream signaling pathway involving insulin receptor substrate 2, phosphatidylinositol 3'-kinase, and p70S6K may play an important role in the development of a broad spectrum of plasma cell tumors.

Animals↗
PubMed2000

Monoclonal antibodies against porcine macrophages.

Two mouse monoclonal antibodies (MAB) (clones 2G6 and 2B10) directed against porcine macrophages are described that are suitable for use in immunohistochemistry, FACS analysis and western blot. As immunogen, porcine cells from bronchoalveolar lavage (BAL) were used. The MABs obtained belonged to the mouse IgG1 subclass. The molecular weights of the corresponding antigens were detected by western blot under non-reducing conditions (2G6: 140-150kDa; 2B10: 140-145kDa). For specificity screening, porcine snap-frozen tissues of lung, lung lymph node, tonsil, spleen, thymus, brain, liver, gut and kidney were used. The MABs were able to identify cell populations of the mononuclear phagocytic system in these organs. While MAB 2G6 detected tissue macrophages (sinusoidal lymph node macrophages, red pulp spleen macrophages, Kupffer cells, Langerhans cells, thymus macrophages, macrophages of lung and macrophages of kidney), MAB 2B10 stained cells scattered in the lymph node (subsinusoidal, interfollicular and follicular macrophages) and in the lung interstitium. Additionally, it showed reactivity with Kupffer cells, spleen and kidney macrophages. An immunoreactivity of the MABs could be established also for human but not for bovine and avian macrophages. By flow cytometric analysis, MAB 2B10 reacted with a subpopulation of BAL and peritoneal cells. Antibody 2G6 detected macrophages of the BAL and the peritoneal fluid as well as peripheral blood monocytes.

Animals↗
PubMed2000

A comprehensive characterization of the T-cell antigen receptor complex composition by microcapillary liquid chromatography-tandem mass spectrometry.

It has become apparent that many intracellular signaling processes involve the dynamic reorganization of cellular proteins into complex signaling assemblies that have a specific subunit composition, function, and subcellular location. Since the elements of such assemblies interact physically, multiprotein signaling complexes can be isolated and analyzed. Recent technical advances in highly sensitive protein identification by electrospray-tandem mass spectrometry have dramatically increased the sensitivity with which such analyses can be performed. The T-cell antigen receptor (TCR) is an oligomeric transmembrane protein complex that is essential to T-cell recognition and function. The extracellular protein domains are responsible for ligand binding while intracellular domains generate and transduce signals in response to specific receptor-ligand interactions. We used microbore capillary chromatography-tandem mass spectrometry to investigate the composition of the TCR protein complex isolated from resting and activated cells of the murine T-cell line CD11.3. We identified all the previously known subunits of the TCR/CD3 complex as well as proteins previously not known to associate with the TCR. The catalytic activities of some of these proteins could potentially be used to interfere pharmacologically with TCR signaling.

Amino Acid Sequence↗
PubMed2000

Proteomics meets cell biology: the establishment of subcellular proteomes.

Proteome research aims to unravel the biological complexity encoded by the genome. Due to the complexity of higher eukaryotic cells, single-step characterization of a proteome is likely to be difficult to achieve. However, advantage can be taken of the macromolecular architecture of a cell, e.g., subcellular compartments, organelles, macromolecular structures and multiprotein complexes, to establish subcellular proteomes. This review highlights recent developments in this area of proteomics, namely the establishment of two-dimensional electrophoresis (2-DE) reference maps of subcellular compartments and organelles as well as the characterization of macromolecular structures and multiprotein complexes using a proteomics approach.

Proteome↗
PubMed2000

An interdisciplinary approach to the care of patients with Wegener's granulomatosis: long-term outcome in 155 patients.

OBJECTIVE: To examine the outcome in 155 consecutive patients with Wegener's granulomatosis (WG) followed up for a median of 7 years. METHODS: Treatment was adapted to the activity and extent of disease, with regular evaluation by an interdisciplinary team accompanied by group education about vasculitis. RESULTS: The estimated median survival time was 21.7 years (95% confidence interval [95% CI] 15.60-27.86). Twenty-two patients died; 19 deaths were attributable to WG and/or its treatment. Significant predictors of survival at diagnosis were age >50 years (hazard ratio [HR] 5.45, 95% CI 1.97-15.02), kidney involvement with impaired renal function (HR 5.42, 95% CI 1.76-16.68), and lung involvement (HR 3.75, 95% CI 1.26-11.16). At some stage, 142 patients received prednisone and cyclophosphamide (CYC), usually as daily CYC plus mesna as uroprotection, 50 patients received trimethoprim/sulfamethoxazole, and 45 received methotrexate. Complete remission was achieved in 83 of the 155 patients. One or more relapses occurred in 99 patients after either complete or partial remission. CYC-induced cystitis and myelodysplastic syndrome occurred in 17 and 11 patients, respectively. A cumulative dose of 100 gm or more of CYC resulted in a 2-fold greater risk of CYC-related morbidity than with lower CYC doses. Serious infections occurred in 41 patients. CONCLUSION: An interdisciplinary approach to the care of 155 WG patients resulted in a median survival of >21 years. Kidney or lung involvement at diagnosis was predictive of a >3-fold higher mortality. Although CYC remains essential in the treatment of WG, it was administered as briefly as possible and under close surveillance to avoid permanent CYC-related morbidity, which can lead to serious therapeutic problems in chronic relapsing WG.

Adolescent↗
PubMed2000

Assessment of the geometry of human finger phalanges using quantitative ultrasound in vivo.

Quantitative Ultrasound (QUS) methods have been shown to be useful in the assessment of bone status. Nevertheless, ultrasound transmission depends on a variety of skeletal parameters, and a detailed understanding of ultrasound propagation through bone is important for the accurate interpretation of QUS results. In this study we wanted to elucidate the pathways of an ultrasound wave through finger phalanges and determine correlations between geometric and QUS parameters. Phalanges of a subject group were measured using QUS and magnetic resonance imaging (MRI). MRI was used for the derivation of the geometric parameters. Similar assessments were performed on cylindrical tubes and with a simulation program. New parameters related to speed of sound (SOS) and amplitude of the wave (A2P) were calculated. Strong correlations between QUS parameters and morphologic cross-sectional areas were observed in vivo and in phantoms. Similar correlations could be found in the calculations using the simulation software. Cross-sectional cortical area, medullary canal area and relative cortical area could be calculated from the QUS parameters (subjects: R2 = 0.71 for cortical area, R2 = 0.45 for medullary canal area and R2 = 0.61 for relative cortical area; phantoms: R2 = 0.98 for cortical area, R2 = 0.78 for medullary canal area and R2 = 0.77 for relative cortical area). In vivo, phantom and simulation results consistently showed that SOS was correlated with cortical area but not with medullary canal area while the opposite was found for A2P. Pathways of the ultrasound wave through solid cortical bone and the medullary canal could be identified and the propagation of the wave could be depicted. These results help to interpret QUS findings and provide information that may be helpful in improving the performance of QUS.

Adult↗
PubMed2000

Computed chest tomography in an animal model for decompression sickness: radiologic, physiologic, and pathologic findings.

This study was conducted to investigate the early pulmonary effects of acute decompression in an animal model for human decompression sickness by CT and light microscopy. Ten test pigs were exposed to severe decompression stress in a chamber dive. Three pigs were kept at ambient pressure to serve as controls. Decompression stress was monitored by measurement of pulmonary artery pressure and arterial and venous Doppler recording of bubbles of inert gas. Chest CT was performed pre- and postdive and in addition the inflated lungs were examined after resection. Each lung was investigated by light microscopy. Hemodynamic data and bubble recordings reflected severe decompression stress in the ten test pigs. Computed tomography revealed large quantities of ectopic gas, predominantly intravascular, in three of ten pigs. These findings corresponded to maximum bubble counts in the Doppler study. The remaining test pigs showed lower bubble grades and no ectopic gas by CT. Sporadic interstitial edema was demonstrated in all animals--both test and control pigs--by CT of resected lungs and on histologic examination. A severe compression-decompression schedule can liberate large volumes of inert gas which are detectable by CT. Despite this severe decompression stress, which led to venous microembolism, CT and light microscopy did not demonstrate changes in lung structure related to the experimental dive. Increased extravascular lung water found in all animals may be due to infusion therapy.

Acute Disease↗
PubMed2000

Portal venous calcifications 20 years after portosystemic shunting: demonstration by spiral CT with CT angiography and 3D reconstructions.

BACKGROUND: Evaluation of the value of spiral computed tomography (SCT), and postprocessing procedures in patients with extensive portal venous calcifications 20 years after portosystemic shunting was performed. METHODS: In two patients spiral CT (SCT) examinations of the abdomen (slice thickness 3 mm, table feed 6 mm/s) were performed prior and after application of 150 ml of contrast material administered at a flow rate of 4 ml/s. Axial images were reconstructed at 2 mm increments for postprocessing procedures and 6 mm increments for axial source images. Postprocessing was performed with a maximum intensity projection (MIP) and shaded surface display (SSD) imaging program. RESULTS: In both cases preoperative plain film radiography of the chest and abdomen showed large curvilinear calcifications located at the upper quadrant of the abdomen. The calcifications were directed along the expected axis and position of the portal vein and the portosystemic venous anastomosis. Axial CT slices and CTA showed that the calcifications were located in the vessel wall and that the portal vein lumen as well as the portosystemic venous anastomosis were patent. CONCLUSION: Long-standing portal hypertension is capable of causing portal venous calcifications due to mechanical stress to the vessel wall even years after performing portosystemic shunting. Typically, the calcifications are directed along the expected axis and position of the portal vein. SCT of the portal venous system is a reliable method to differentiate between calcifications in a thrombus or in the vessel wall, which may have therapeutic significance.

Angiography↗