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S Weber

Publications and source records attributed to S Weber.

At least 145 records · Page 8Linked to original sources
PubMed1998

Echocontrast enhanced transcranial colour-coded duplex offers improved visualization of the vertebrobasilar system.

OBJECTIVES: By means of transcranial colour-coded duplex sonography (TCCD) through the foramen magnum, the intracranial vertebral arteries (VAs) and the basilar artery (BA) can be investigated. In this study we evaluated the additional diagnostic value of echocontrast administration in patients with an insufficient pre-contrast TCCD investigation of the vertebrobasilar system. MATERIAL AND METHODS: In 22 patients the intracranial VAs and the proximal, middle and distal BA were evaluated before and after the application of 4 g of the echocontrast agent Levovist. The length of the different vessel segments visualized on colour mode before and after echocontrast, and the diagnostic benefit and the diagnostic confidence were assessed. RESULTS: Echocontrast enlarged in each vessel segment the length that could be visualized. Using echocontrast, in 5/22 patients (23%) definite and probable pathological findings unnoted in the native scans were detected. In 12 additional patients (55%) the investigator and the clinician became confident with the vascular diagnosis by echocontrast to a degree that angiography could be avoided. In only 3/22 patients (14%) no gain and in 2/22 patients (9%) an insufficient diagnostic gain was noted. CONCLUSIONS: Our study demonstrates that echocontrast provides effective Doppler signal enhancement and considerably increases the diagnostic gain of TCCD in the intracranial vertebral and basilar vasculature.

Adult↗
PubMed1998

Comparison of free-living amoebae in hot water systems of hospitals with isolates from moist sanitary areas by identifying genera and determining temperature tolerance.

Legionella-contaminated hot water systems and moist sanitary areas in six hospitals were sampled for amoebae by following a standardized collection protocol. Genus identifications and temperature tolerance determinations were made. Amoebae identified as Hartmannella vermiformis (65%), Echinamoebae spp. (15%), Saccamoebae spp. (12%), and Vahlkampfia spp. (9%) were detected in 29 of 56 (52%) hot water samples. Twenty-three of 49 (47%) swabs obtained from moist areas were amoeba positive. The following genera were identified: Acanthamoeba (22%), Naegleria (22%), Vahlkampfia (20%), Hartmannella (15%), and Vanella (7%). The temperature tolerance of amoebae from hot water systems was strikingly different from that of amoebae from moist areas. At 44 degrees C on agar, 59% of amoebic isolates sampled from hot water systems showed growth. The corresponding value for isolates from moist areas was only 17%. Six Acanthamoeba isolates from the moist areas were considered potential pathogens. Four Hartmannella and two Saccamoeba isolates from hot water could be cultured at 53 degrees C.

Acanthamoeba↗
PubMed1998

Increased state of activation of CD4 positive T cells and elevated interferon gamma production in pouchitis.

BACKGROUND: Immunoregulatory abnormalities of T cells might be of importance in the pathogenesis of pouchitis after ileoanal pouch anastomosis (IAP). AIMS: To characterise T cell subsets, their state of activation, and production of cytokines in inflamed and non-inflamed pouches in patients with ulcerative colitis (UC) and familial adenomatous polyposis (FAP). The influence of T cell activation on mucosal transformation was also studied. PATIENTS: Mucosal biopsy specimens were taken from 42 patients with IAP (33 with UC and nine with FAP). METHODS: Mononuclear cells were isolated by standard techniques and characterised by three colour flow cytometry. Interferon gamma (IFN-gamma) production was studied using the ELISPOT technique. RESULTS: In patients with UC with pouchitis there was a significant increase in the CD4:CD8 ratio, expression of activation markers on CD3+ cells, and number of IFNgamma producing mononuclear cells compared with patients with UC without pouchitis (CD4:CD8 ratio 1.3 (range 0.7-2.7) versus 0.6 (0. 1-1.0), p=0.012). In addition, a positive correlation between increased crypt depth and the number of CD4+ cells (r=0.57) was shown. CONCLUSION: The observed increase in activated mucosal CD4+ T cells and IFN-gamma production might lead to mucosal destruction and crypt hyperplasia as seen in pouchitis.

Adult↗
PubMed1998

Potential and limitations of echocontrast-enhanced ultrasonography in acute stroke patients: a pilot study.

BACKGROUND AND PURPOSE: Ultrasonography (US) is a well-established method used to assess the brain-supplying arteries in the acute stroke setting. However, several technical and anatomic limitations are known to reduce its diagnostic accuracy and confidence level. Echocontrast agents (ECA) are known to improve the signal-to-noise ratio by enhancing the intensity of the reflecting Doppler signal. We undertook this prospective study to evaluate the diagnostic value of ECA in a consecutive, nonselected cohort of acute stroke patients with insufficient native US investigations. METHODS: During a 1-year period, 25 patients were examined within 48 hours of the onset of stroke. The need for ECA was due to an insufficient transtemporal (n=18), transforaminal (n=4), or extracranial (n=3) imaging of arteries potentially involved in the ischemic event. In 12 patients, a diagnostic suspicion could natively be raised, whereas in the other 13 patients, the strongly reduced image quality did not allow for any neurovascular conclusions. Four grams of Levovist was injected at a concentration of 200 mg/mL and 400 mg/mL for the extracranial and transcranial insonations, respectively. The effect of the echocontrast enhancement was assessed with respect to (1) signal enhancement, (2) image quality, (3) final diagnostic confidence, and (4) the need for additional neurovascular imaging methods. RESULTS: In all but one patient (96%), a strong signal enhancement was noted, leading to a moderate (n=11) or strong improvement (n=10) of the transcranial image quality. Thus in a total of 18 patients (72%), the echoenhancement provided a neurovascular diagnosis of sufficient confidence. This led to the confirmation of the previously suspected findings and disclosed three further occlusions and four stenoses of the intracranial arteries. In contrast, for the three extracranial examinations the image quality was not sufficiently improved because of persistent color artifacts derived from adjacent neck vessels. Besides the seven patients with inconclusive examinations, five patients with conclusive echoenhanced US studies (48% in total) demanded additive neurovascular imaging studies, based on the clinical decision of the attending physicians. This led to confirmation of all high-confident sonographic diagnoses. CONCLUSIONS: In summary, in approximately three fourths of our acute stroke patients with insufficient native US investigations, echocontrast enhancement enabled a reliable neurovascular diagnosis, allowing the cancellation of additive neurovascular imaging procedures in half of our cohort. Our preliminary results suggest that ECA can reasonably support the early cerebrovascular workup in the acute stroke setting.

Acute Disease↗
PubMed1998

Diagnostic impact and prognostic relevance of early contrast-enhanced transcranial color-coded duplex sonography in acute stroke.

BACKGROUND AND PURPOSE: We sought to evaluate the diagnostic value of echo-enhanced transcranial color-coded duplex sonography (TCCD) and the clinical relevance of vascular pathology assessed by sonography for early clinical outcome in acute ischemic stroke. METHODS: We present 23 consecutive patients with an anterior circulation stroke in whom clinical examination, CT, and ultrasonography were performed within 5 hours after the onset of symptoms. Transcranial Doppler sonography (TCD) and unenhanced and contrast-enhanced TCCD (Levovist, 4 g, 300 mg/mL) were compared for their ability to detect middle cerebral artery (MCA) occlusion and flow velocity reduction suggesting hemodynamic impairment in the MCA distribution pathway. Sonographic examination times were registered. Baseline clinical characteristics and CT findings were assessed. Neurological deficit was quantified according to the National Institutes of Health Stroke Scale score, with an early clinical improvement defined as decrease of the score by 4 or more points or a complete resolution of the deficit on day 4. RESULTS: Contrast-enhanced TCCD enabled diagnosis of intracranial vascular pathology in 20 affected hemispheres, whereas unenhanced TCCD and TCD were conclusive in 7 and 14 hemispheres, respectively (P=0.0001). Contrast-enhanced TCCD was superior in evaluating distal carotid (carotid-T) occlusion and differentiating major vessel occlusions from patent arteries with flow velocity diminution. Mean examination time for enhanced TCCD ranged from 5 to 7 minutes, depending on the number of investigated vessels (without or with MCA branches). Logistic regression selected a patent MCA without reduced blood flow velocity as the only independent predictor for an early clinical improvement (P<0.01). CONCLUSIONS: Contrast-enhanced TCCD is a promising tool for early prognosis in anterior circulation stroke. It is considered superior to unenhanced TCCD and TCD.

Acute Disease↗
PubMed1998

[Arrhythmogenic effects of extracorporal lithotripsy in desynchronized mode with a later generation lithotriptor].

Extracorporal lithotripsy has transformed the treatment of renal stones. However, the shock waves can generate arrhythmias which may be severe. To prevent them, the shocks were synchronised to the absolute refractory period of the cardiac cycle with a corollary, an increase in the procedure time. The latest generation of lithotriptors have a number of technical improvements allowing desynchronisation but with a high theoretic risk of arrhythmias. The aim of this study was to assess the arrhythmogenic effects of desynchronised shocks by Holter ECG monitoring during the procedure. This was a prospective randomised study: 25 patients with no previous cardiovascular history were included: 15 men and 10 women with a mean age of 45 years. The originality of this study was the delivery of shock waves in two phases (synchronised versus desynchronised) in a random fashion, the order being unknown to the cardiologist interpreting the recordings. In the synchronised mode, none of the patients developed an arrhythmia. On the other hand, in the desynchronised mode, hyperexcitability was observed in 7 patients, supraventricular in 6 cases (atrial extrasystoles and atrial doublets) and ventricular in 4 cases (VES, ventricular doublets and 1 unsustained ventricular tachycardia). These arrhythmias were asymptomatic and regressed spontaneously. The authors conclude that although they are arrhythmogenic, desynchronised procedures with the latest lithotriptors are acceptable, provided that the patients undergo a cardiological examination beforehand to identify high risk patients and that there is adequate monitoring during the procedure in the presence of an anaesthetist.

Adult↗
PubMed1998

[Transluminal coronary angioplasty in the acute phase of myocardial infarction].

The objective of the treatment of myocardial infarction is to reestablish patency of the occluded artery as soon as possible. Two methods have been validated: intravenous thrombolysis which is easy to perform, and transluminal coronary angioplasty requiring expensive infrastructures and a skilled medical team but which has a higher success rate of restoring arterial patency. Angioplasty is indicated in cardiogenic shock and cases in which there is diagnostic uncertainty or a contraindication to thrombolysis. In addition, its superiority over thrombolysis has been clearly demonstrated in the following indications: 1) primary angioplasty if proper facilities with an experienced team are available in less than 45 minutes and 2) after failed thrombolysis (rescue angioplasty). The use of stents improves the results of primary angioplasty. Angioplasty and thrombolysis are not rival techniques: the choice depends on local conditions (proximity to a catheterization laboratory with a trained medical team) and the clinical context (presence of "high-risk" criteria). Their association (prehospital thrombolysis followed by immediate angioplasty) is the object of prospective clinical trials.

Angioplasty, Balloon, Coronary↗
PubMed1998

[Bartonella quintana endocarditis. Aortic localization and mitral valve abscess].

Bartonella Quintana is an exceptionally rare cause of endocarditis. The frequency of this condition is increasing and is probably underestimated because of the difficulty in diagnosing. The clinical context is that of socially deprived classes, the agent of transmission of the germ being body lice. The commonest valve affected is the aortic valve. This infection may also give rise to a mitral annulus abscess, as in this particular case. The diagnosis should be suspected in all cases of endocarditis with negative blood cultures in socially deprived patients as special diagnostic methods are required. Bartonellosis serology and drainage of effusions to perform a Gimenez stain to show intra-cellular bacteria and a polymerase chain reaction to sequence the nucleic acids, will give an accurate diagnosis. Similarly, the operative specimens should be sent to a specialised department for the culture of these bacteria (in France, the Marseille Ricketsioses Institute). The treatment of Bartonella endocarditis is very controversial. The usual recommendations are an association of betalactamines and an aminoside for one month and macrolides or tetracyclines. There is lack of consensus about follow-up. It would seem prudent to perform a clinical examination to search for a relapse of the infection and monthly serologies until they return to normal values.

Abscess↗
PubMed1997

One-week and six-month angiographic controls of stent implantation after occlusive and nonocclusive dissection during primary balloon angioplasty for acute myocardial infarction.

We prospectively assessed in 124 consecutive patients by means of 1-week and 6-month follow-up angiograms the rate of reocclusion and restenosis of coronary stenting with Palmaz-Schatz stents after occlusive and nonocclusive dissection during primary balloon angioplasty for acute myocardial infarction (AMI). Patients were further evaluated clinically at 1 year. Stenting was performed on large (>3.2 mm) coronary arteries for suboptimal results (47%), occlusive (8%), or nonocclusive dissections (45%) after balloon angioplasty. Stents were delivered using the bare stent technique and high pressure inflations (>12 atm). All patients received ticlopidine 250 mg (500 mg if weight was >80 kg) and aspirin 100 mg for 1 month. No patient received warfarin. At 1 week, 6 patients died of cardiogenic shock and 2 of right ventricular infarction. One subacute occlusion occurred at day 14. At 6 months, in 95 patients, the angiographic restenosis rate (>50% diameter stenosis) was 19%. One-year clinical follow-up, available in 55 patients, indicated cardiac death in 5, and repeat revascularization in 3. Thus, coronary stenting on large (>3.2 mm) coronary arteries after occlusive and nonocclusive dissection during primary balloon angioplasty for AMI using bare Palmaz-Schatz stents, high pressures, ticlopidine, and aspirin is safe. Our reocclusion and restenosis rates are similar to those of trials on elective stenting in stable patients.

Aged↗
PubMed1997

CD43 (leukosialin, sialophorin) expression is differentially regulated by retinoic acids.

CD43 (leukosialin, sialophorin), a cell-surface associated mucin that is constitutively expressed at high levels on most leukocytes, is thought to be involved in cell activation and adhesion. We here provide evidence that the vitamin A metabolites all-trans and 13-cis retinoic acid up-regulate CD43 on human leukemic (HMC-1) mast cells, as determined by flow cytometry, Western blot analysis, and by semiquantitative reverse transcriptase-polymerase chain reaction. Enhanced CD43 expression was accompanied by a strong increase in anti-CD43-mediated, LFA-1-dependent homotypic aggregation of HMC-1 cells, demonstrating that newly synthesized CD43 is functionally active in transmitting signals across the plasma membrane which result in enhanced cellular adhesion. CD43 expression was also enhanced in response to retinoic acids on isolated human skin mast cells and human monocytes, but not on cells of the basophilic cell line KU-812 and promyelocytic HL-60 cells, indicating that these agents might act in a cell-type specific manner. These combined result-point to a novel aspect in the regulation of CD43. Possibly, vitamin A metabolites act directly on the CD43 gene, since putative retinoic acid response elements have been detected within its regulatory regions.

Antigens, CD↗
PubMed1997

Leukosialin (CD43) is proteolytically cleaved from stimulated HMC-1 cells.

Leukosialin (CD43), the major sialoprotein on circulating leukocytes, has been previously described to be down-regulated on neutrophils following activation with phorbol myristate acetate (PMA). The other single cells previously examined, blood lymphocytes, do not down-regulate CD43 when stimulated by PMA. Recently, we have characterized leukosialin on the human mast cell line HMC-1 and observed that leukosialin is down-regulated after stimulation with PMA. In the present study, we have investigated the mechanism of PMA-mediated down-regulation of CD43 on HMC-1 cells (subclone 5C6). PMA caused the release of soluble leukosialin (123 kD) during HMC-1 cell activation. The molecular weight of soluble leukosialin was nearly identical to that of the cell-membrane bound molecule, suggesting a cleavage proximal from the cell membrane. Inhibitors of serine proteases, like phenylmethylsulphonyl fluoride (PMSF), benzamidine and 3, 4-dichloroisocoumarin, blocked the PMA-mediated cleavage of CD43. In all experiments, the inhibition of CD43-down-regulation was dependent on the concentration of protease inhibitors. Treatment of HMC-1 cells with various proteases (trypsin, alpha-chymotrypsin, elastase, papain, nagarse) substantially decreased anti-CD43 binding capacity and caused the release of soluble leukosialin (116 kD) or its fragments into the supernatant. Pretreatment of HMC-1 cells with neuraminidases from Vibrio cholerae or Arthrobacter ureafaciens resulted in an increased sensitivity of CD43 against proteases, whereas the effects of PMA were not influenced. In conclusion, proteolytic cleavage of CD43 is described for the first time in a cell other than neutrophils, namely HMC-1 cells. Our results suggest that serine proteases are involved in the PMA-mediated down-regulation of leukosialin on HMC-1 cells.

Antigens, CD↗
PubMed1997

Role of molecular epidemiology in infection control.

Molecular typing methods have enabled infection control personnel to investigate outbreaks and endemic nosocomial infections more quickly and thoroughly than they could have with basic epidemiologic and microbiologic methods. This article reviews molecular typing methods that have been used successfully in the practice of hospital epidemiology. Included is an explanation of the basic principles of these methods and a description of their strengths and weaknesses.

Cross Infection↗
PubMed1997

Human leukaemic (HMC-1) and normal skin mast cells express beta 2-integrins: characterization of beta 2-integrins and ICAM-1 on HMC-1 cells.

Mast cells are bone marrow-derived, ubiquitous connective tissue resident cells. However, their mechanisms of migration, the distribution of immature and mature cells and their interaction with other inflammatory cells are largely unclarified. Possibly, beta 2-integrins play an important role in these processes. In the present investigation, the authors studied the expression and regulation of the beta 2-integrins LFA-1 (CD11a/CD18), Mac-1 (CD11b/CD18), p150,95 (CD11c/CD18) and of the LFA-1/Mac-1 counter-receptor intercellular adhesion molecule-1 (ICAM-1; CD54) on leukaemic (HMC-1 cell subclone 5C6) and on normal mature human skin mast cells. The HMC-1 cells clearly expressed CD11a, CD18 and CD54, while expression of CD11b and CD11c was low. The apparent molecular weights were 180 kDa (CD11a), 95 kDa (CD18) and 90 kDa (CD54) as determined by Western blot analysis. Phorbol myristate acetate (PMA) induced a time- and dose-dependent up-regulation of CD11a, CD11b, CD11c, CD18 and CD54 that was inhibited by cycloheximide, suggesting a dependence on de novo protein synthesis. Enhanced expression of CD11a, CD11b, CD11c and CD18 could also be confirmed at the gene level as demonstrated by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Increased expression of LFA-1/ICAM-1 in response to PMA was accompanied by strong enhancement of homotypic cell aggregation, suggesting that newly synthesized LFA-1/ICAM-1 is functionally active. In order to determine a physiologically relevant way of mast cell beta 2-integrin modulation, several cytokines and chemotactic mediators (interleukin-4, IL-4; nerve growth factor beta, NGF beta; C5a; and leukotriene B4, LTB4) were tested for their influence on adhesion molecule cell surface density. Only LTB4 was shown specifically to up-regulate CD11a and CD18, but not CD11b or CD11c. The presence of CD11a, CD11c and CD18 could be confirmed on a low percentage of normal skin mast cells by immunofluorescence, using a double staining technique. In comparison to normal skin, a significantly higher percentage of CD18+ mast cells was found in inflammatory dermatoses such as psoriasis vulgaris, atopic dermatitis and lichen planus. Therefore, mast cell beta 2-integrins possibly play an important role during homing of immature mast cells as well as during the interaction of activated mast cells with other inflammatory cells.

Base Sequence↗
PubMed1997

[Vascularization patterns in focal liver lesions: comparison of plain and signal-enhanced amplitude-modulated color duplex ultrasonography].

PURPOSE: Morphology of focal liver lesions was studied by power Doppler. Plain images and images after i.v. application of galactose-based microbubbles (Levovist, Schering AG) were compared. METHODS: 21 patients with focal liver lesions were studied by power Doppler before and after application of the signal enhancer. RESULTS: In lesions that showed short pulsations in plain studies, vascular structures were visible after application of the signal enhancer. In hepatocellular carcinomas, multiple arteries with small diameter became visible. Peripheral veins were detected in metastases. A large feeding artery was detected in 1/2 haemangiomas with flow and in a focal nodular hyperplasia. CONCLUSION: In comparison to plain amplitude-modulated colour-coded duplex ultrasound, vascular patterns of focal liver lesions were more clearly visible after injection of a signal-enhancer.

Adult↗
PubMed1997

[Activation of blood coagulation and fibrinolysis after angiocardiography with ionic and non-ionic contrast media].

PURPOSE: To study the effects of a ionic (amidotrizoate) and a non-ionic x-ray contrast medium (iopromid) during routine levocardiography and coronary angiography, we employed assays that detect reaction products of thrombin and plasmin to assess the activation of the haemostatic system. METHODS: Subsequent to informed consent, 20 patients were randomly assigned to receive either amidotrizoate or iopromid during standard levocardiography and coronary angiography in a double-blind comparative study. Groups were comparable in respect of age, weight, sex and severity of the disease. No anticoagulation was provided. Coronary angiography was performed according to a standardised protocol. Consumption of contrast media and duration of the examination were comparable in both groups. RESULTS: Thrombin generation (F.1+2) and thrombin activity (TAT) were higher with the ionic contrast medium but did not attain statistical significance. Fibrin generation and degradation as expressed by D-dimer fibrin split products was significantly increased in patients who had been receiving amidotrizoate (p < 0.05, U-Test). CONCLUSION: The non-ionic x-ray contrast medium induced significantly less haemostatic activation in vivo than did the ionic medium amidotrizoate. These data suggest that earlier in vitro observations of more pronounced anticoagulant effects of ionic x-ray contrast media are of limited significance for the evaluation of in vivo effects of x-ray contrast media on haemostatic function.

Angiocardiography↗