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Biomedical subjects

U Hoffmann

Publications and source records attributed to U Hoffmann.

At least 19 recordsLinked to original sources
PubMed2003

Experience with transcatheter closure of secundum atrial septal defects using the Amplatzer septal occluder: a single centre study in 236 consecutive patients.

AIM: To evaluate the safety and efficacy of transcatheter closure of secundum atrial septal defects (ASD) with the Amplatzer septal occluder. METHODS: 236 consecutive patients with a significant ASD (age 6 months to 46 years, median 5 years; body weight 6.5-79 kg, median 18 kg) were considered for transcatheter closure with the Amplatzer septal occluder; 18 patients with defects that were too large or with a deficient inferior margin were excluded from attempted transcatheter closure after initial transthoracic (4) or transoesophageal echocardiography (14). RESULTS: At cardiac catheterisation, devices were not implanted in 18 patients because the stretched diameter of the ASD was too large (4), the device was unstable (4), compromised the mitral valve (1), or obstructed the upper right pulmonary vein (1); eight patients with additional systemic or pulmonary vein anomalies (5) or a Qp:Qs less than 1.5 (3) were excluded after angiographic and haemodynamic assessment. Thus ASD closure was done successfully in 200 patients (procedure time 25-210 minutes, median 66 minutes; fluoroscopy time 2.5-60 minutes, median 12 minutes), among whom 22 had multiple ASDs (14) or a septal aneurysm (8). The diameter of the devices ranged between 6-34 mm. Severe procedure related complications (retroperitoneal bleeding, air embolism) occurred in two cases. At follow up (33 days to 4.3 years, median 2.3 years) complete closure was documented in 94%, with a trivial residual shunt in 12 patients. CONCLUSIONS: The Amplatzer septal occluder is very efficient and offered interventional ASD closure in 84.7% of our group of consecutive patients, with excellent intermediate results.

Adolescent↗
PubMed2003

High sensitivity C-reactive protein in cardiovascular risk assessment. CRP mania or useful screening?

Elevated level of the acute phase reactant C-reactive protein (CRP) is a very sensitive marker of acute inflammatory reactions. Using high sensitivity assays for CRP, recent observations indicate that slightly elevated CRP levels which would be in the normal range of conventional assays are a novel marker for an increased risk for cardiovascular events, especially coronary artery disease and myocardial infarction. Various large scale prospective trials including the Physicians' Health Study and the Women's Health Study revealed that slightly increased hsCRP levels at base line in apparently healthy persons are associated with a 2-fold increase in the risk of a future myocardial infarction. The predictive value of hsCRP was found to be independent from classic risk factors, in particular from elevated serum cholesterol. An increase in hsCRP levels was also associated with a higher risk to develop peripheral artery disease and with a faster progression of carotid artery disease. Until now, treatment with HMG-CoA reductase inhibitors (statins) has been found to be the only medication to consistently decrease hsCRP levels, although by about 15% only. Despite the association of elevated hsCRP levels with future cardiovascular events, routine measurement of hsCRP for cardiovascular risk assessment is currently not recommended because of its low accuracy, the lack of a clear cut-off point for elevated hsCRP levels and the lack of an absolute predictive value. So far, hsCRP remains an interesting potential risk marker for cardiovascular disease whose definite relevance remains to be established.

Arteriosclerosis↗
PubMed2002

Bioequivalence of subcutaneous and intravenous body-weight-independent high-dose low-molecular-weight heparin Certoparin on anti-Xa, Heptest, and tissue factor pathway inhibitor activity in volunteers.

The objective of the study was to demonstrate the bioequivalence of subcutaneously (s.c.) and intravenously (i.v.) administered fixed, high-dose low-molecular-weight heparin (LMWH) on anti-activated factor X activity (anti-FXa). Secondary objectives were the analysis of the pharmacodynamic effects on Heptest, thrombin inhibition, tissue factor pathway inhibitor (TFPI), and the urinary excretion of LMWH in the randomized cross-over study following i.v. and s.c. application of 8000 anti-FXa units LMWH Certoparin in 18 healthy subjects. The bioequivalence following s.c. administration was demonstrated from the antilog of the point estimator for the application differences (s.c. minus i.v.) by an area under the activity-time curve (0-24 h) of 101% (range, 93-110%). LMWH was bioequivalent also on Heptest and TFPI, and was 50% on thrombin inhibition. The urinary excretion of biologically active material was 4.1 and 3.6% following i.v. and s.c. administration, respectively. Differences in the pharmacodynamic parameters of the assays indicate specific biological actions of high and low molecular sacharide chains of the LMWH.

Adult↗
PubMed2001

[Duplex ultrasound for diagnosis of carotid stenosis. Detecting stroke candidates].

In the hands of an experienced examiner, and with consideration being given to defined criteria, duplex sonography of the extracranial arteries supplying the brain is a valid, noninvasive, nonstressful, reproducible and comparatively inexpensive examination procedure. The indication for this examination is established after a cerebral ischemic event, or in patients with an appropriate risk profile. Nevertheless, anatomical variants or technical problems make necessary a further diagnostic work-up in the form of MR or conventional angiography.

Carotid Artery, Internal↗
PubMed2001

[Treating carotid stenosis without surgical trauma. How safe is stenting?].

Because of the reduced stress on the patient, the obviation of surgical trauma and the need for anesthesia, and only brief hospitalization, stent angioplasty is an attractive alternative to surgical treatment of carotid artery stenosis. The data so far available suggest that the results may be expected to equal those obtained with surgery in terms of success rate and complications. The establishment of the indication for this procedure is oriented to the indication for thromboendarterectomy, with certain patient groups possibly benefitting from endoluminal treatment. However, until data from controlled studies become available, stenting of the carotid artery should be limited to scientific studies and be registered with appropriate professional associations.

Angiography↗
PubMed2001

A possible role for the cnidarian homologue of serum response factor in decision making by undifferentiated cells.

We have isolated the serum response factor (SRF) homologue from two hydrozoans, the freshwater polyp Hydra vulgaris and the marine colonial Hydractinia echinata; we have termed the Hydra gene HvSRF and the Hydractinia gene HeSRF. The MADS-box of both genes is identical in sequence and more similar to SRFs of other organisms than to non-SRF MADS-box-containing proteins from other organisms. Within the N terminus of the predicted protein, a motif of 14 amino acids is nearly identical between Hydra and Hydractinia. This motif is absent from other known SRF sequences. In the adult Hydra polyp, SRF is predominantly expressed in cells of the interstitial cell (I-cell) lineage. Expression of SRF ceases when I-cells differentiate into nerve cells, nematocytes, or gland cells. In the course of sexual reproduction in Hydractinia, SRF is expressed in female germ cells. During embryogenesis, SRF transcripts are observed in all blastomeres. Later on, SRF expression is turned off in cells forming the ectodermal layer but further on is expressed in cells of the central cell mass, from which the endodermal epithelial cells and the I-cell lineage originate. Expression eventually becomes restricted to the I-cell lineage. We conclude that hydrozoan SRF is expressed in all these cells, which still have the property for differentiation. In adult Hydra, the abundance of SRF transcripts varies during the day. The pacemaker of this diurnal rhythm is the feeding regime. HvSRF expression decreases by 4 h after feeding and returns to the initial level 12 h after feeding. When feeding is stopped, the cycle of SRF expression persists through the first day when the animals are not fed. It has been shown that feeding partly synchronizes the cell cycle of the epithelial cells but not that of the I-cells. We suggest that the epithelial cells affect SRF expression in I-cells and thereby influence the decision of I-cells to enter a differentiation pathway.

Amino Acid Motifs↗
PubMed2001

High oxygen tension leads to acute cell death in organotypic hippocampal slice cultures.

Increased oxygen tension in the central nervous system can be of relevance in different clinical situations, e.g. hyperbaric oxygen treatment during resuscitation of newborns in asphyxia as well as during seizures in children and adults where the supply of oxygen to tissue is increased by elevated cerebral blood flow. We focused on changes in neuronal tissue by investigating the impact of different oxygen tensions on juvenile rat hippocampal slice cultures using extracellular field potential recordings and propidium iodide (PI) staining for cell death determination. Slice cultures were prepared following the Stoppini technique (postnatal days 6-8). Electrophysiological responses in area CA1 to hilar stimulation were recorded every 15 min after an initial equilibration period of 60 min. Slice cultures maintained in 95% oxygen showed a 53% (S.E.M.=17%; n=10) run-down in amplitudes of the evoked responses over the observation time course of 90 min. In contrast, slice cultures maintained in 19% oxygen showed no run-down in amplitudes (S.E.M.=9%; n=18). PI staining of the slice cultures carried out immediately after the electrophysiological measurements indicated a dramatic cell death rate in the high oxygen tension group compared to those maintained in 19% oxygen. Interestingly, epileptiform activity (seizure-like events, spreading depression-like events) occurred in some slice cultures dependent on oxygen tension. Altered paired-pulse index of evoked responses suggests a loss of GABAergic function, especially in the 95% oxygen tension group. These results demonstrate a high sensitivity to oxygen in juvenile rat hippocampal slice cultures, in contrast to acutely prepared juvenile and adult rat hippocampal slices.

Animals↗
PubMed2001

Afterload reduction in severe aortic regurgitation.

This study was designed to assess the effects of afterload reduction in asymptomatic patients with severe aortic regurgitation (AR) and maintained LV function by cine-MRI. We studied 13 patients at baseline and after 0.2 mg/kg Hydralazine (I.V.). Patients were stratified according to the volumetric LV response to acute afterload reduction: Group I comprised patients with improved LV response; Group II comprised patients with unchanged or deteriorated LV response. Baseline LV function and severity of AR were not significantly different between groups. However, regurgitant fraction decreased (50 +/- 12 vs. 36 +/- 9%; P < 0.03) and cardiac output increased (4.9 +/- 1.4 vs. 7.1 +/- 1.6l/minute; P < 0,001) in Group I and remained unchanged in Group II (54 +/- 10 vs. 55 +/- 10%, P = n.s. and 5.5 +/- 1.4 vs. 6.6 +/- 0.9l/minute; P = n.s.) during maximal vasodilation. Beat-to-beat analysis revealed a decrease of left ventricular endsystolic volume index in group I (48 +/- 13 vs. 37 +/- 9 ml/beat; P < 0.05) and no change in group II (61 +/- 20 vs. 62 +/- 20 ml/beat; P = n.s.). In the natural history of chronic AR, the absence of improved LV performance during acute vasodilation using beat-to-beat analysis by MRI may identify patients with more advanced cardiac adaptation to chronic volume overload.

Adult↗
PubMed2001

The effects of ACE inhibitor therapy on left ventricular myocardial mass and diastolic filling in previously untreated hypertensive patients: a cine MRI study.

Cardiac remodeling in case of hypertension induces hypertrophy of myocytes and elevated collagen content and, subsequently, impaired diastolic filling of the left ventricle. The purpose of this prospective study was to evaluate changes of left ventricular (LV) myocardial mass, as well as diastolic filling properties, in hypertensive patients treated with the ACE inhibitor fosinopril. Sixteen hypertensive patients with echocardiographically documented LV hypertrophy and diastolic dysfunction received fosinopril (10-20 mg daily). Measurements of LV myocardial mass and properties of diastolic filling (peak filling fraction (PFF); peak filling rate (PFR)) were performed prior to medication, as well as after 3 and 6 months of therapy using cine magnetic resonance imaging (MRI). Ten healthy subjects served as a control group. LV myocardial mass (g/m2) decreased continuously within 3-6 months of follow-up by 32% (148 +/- 40 vs. 120 +/- 26 vs. 101 +/- 22 g/m2; P < 0.0001/0.005). The extent of regression correlated to the severity of LV hypertrophy at baseline (r = 0.77; P < 0.004). Early diastolic filling increased significantly within 6 months of therapy (PFF (%): 36 +/- 6 vs. 61 +/- 7, P < 0.0001; PFR (mL/second): 211 +/- 48 vs. 282 +/- 48, P < 0.001). Cine MRI can be used to assess the time course of pharmacological effects on cardiac remodeling in the course of hypertension. ACE inhibitor therapy results in a significant reduction of LV mass within 3 months and is accompanied by a normalization of diastolic filling that is completed after 6 months.

Adult↗
PubMed2001

Central retinal artery occlusion in association with an aneurysm of the internal carotid artery.

PURPOSE: To report an unusual case of central retinal artery occlusion in a 41-year-old woman. DESIGN: Interventional case report. METHODS: A 41-year-old woman presented with sudden and painless decrease of visual acuity of the left eye. Indirect ophthalmoscopy revealed the typical fundus findings of a central retinal artery occlusion. The fovea was spared by a cilioretinal arteriole. RESULTS: Cerebral angiography showed an aneurysm of the left internal carotid artery, measuring approximately 1.7 x 1.5 x 1.7 cm. The aneurysm was located in close proximity to the ophthalmic branch. CONCLUSION: Aneurysm of the intracranial arteries should be included in the differential diagnosis of central retinal artery occlusion in young patients.

Adult↗
PubMed2001

Quantification of coronary artery calcification in patients with FH using EBCT.

BACKGROUND: Calcification of the coronary vessel wall is regarded as a marker of advanced coronary atherosclerosis. METHODS: To test whether patients with heterozygous familial hypercholesterolemia (FH) exhibit excessive calcification of the coronary vessel wall, we quantified coronary artery calcium in LDL-apheresis treated FH-patients with known severe coronary artery disease (CAD) (n = 10), in patients with moderate hypercholesterolemia and known severe CAD (n = 10), and in asymptomatic controls (n = 10) using electronic beam CT. The total coronary calcium score (Agatston-Score), the number of calcified lesions and the calcified plaque volume were evaluated for this study. RESULTS: CAD-patients with FH, although on average 10 years younger, had a significantly higher total coronary calcium score (702/2018/2890), number of lesions (34/43/49) and calcified plaque volume (700/1818/2313) compared to patients with CAD only (480/641/1362, 10/16.5/22, 480/588/1209, respectively) and controls (10/47/137, 2/4/10, 15/50/144, respectively). Furthermore, we observed a significant correlation (r = 0.93; P < 0.01) between LDL-cholesterol levels (pretreatment levels of the CAD-FH group) and the total coronary calcium score in all three groups. Our results demonstrate that coronary artery calcification is more extensive in CAD-patients with FH than in CAD-patients with moderate hypercholesterolemia. In addition, we provide evidence that the amount of calcium in the coronary vessel wall in FH patients result from a long lasting history of elevated LDL-Cholesterol levels. CONCLUSION: These findings emphasize the significance of LDL-cholesterol as a risk factor for atherosclerosis and underline the importance of early diagnosis of CAD and early cholesterol lowering therapy in FH patients.

Calcinosis↗
PubMed2001

In situ optical microscopic recording of slip line development during plastic deformation of Cu-15at%Al single crystals with high resolution--estimation of dislocation velocities.

Observations and measurements of slip line evolution during plastic deformation are performed by optical microscopic video recording. In addition, high resolution in time is achieved by means of photodiodes positioned in the intermediate image plane of the microscope. Examples of measurements at room temperature on short-range ordered Cu-15at%Al single crystals are given and evaluated to estimate the velocities of edge and screw dislocation groups from the observed rates of growth of slip steps in height and in length, respectively, on one side of the specimen. By means of a second microscope observing the opposite side, the average rates for the dislocations to cross the whole specimen can be obtained. The measured values are discussed in terms of the movement of correlated dislocation groups in the crystals.

Journal Article↗
PubMed2001

Administration of 100% oxygen in diving accidents--an evaluation of four emergency oxygen devices.

As the use of oxygen enhances the resorption of gas bubbles in decompression illness, it is recommended and generally accepted that the inspired oxygen concentration in emergency treatment of diving accidents has to be as close to 100% as possible. Therefore, several emergency oxygen devices are offered to the diving community but only with little data in literature on the efficacy of these devices. We tested four emergency oxygen devices with respect to efficacy of oxygen supply and breathing comfort at rest. Nine blinded volunteers had to breathe from the four systems with face mask and mouthpiece as well. Gases were measured with mass spectrometry during a 3 min interval from a capillary port close to the subject. The results showed that none of the systems was able to deliver 100% oxygen all the time, but in three systems inspiratory oxygen values were achieved, although in one system the nitrogen wash-out was slowed due to air contamination during inspiration. The fourth tested system frequently supplied the subjects simply with air while breathing at rest. We conclude from our study that it is difficult to achieve oxygen levels close to 100% in practice. Even in a perfectly working system, the interface between device and subject is a source of entrained air, especially when oxygen breathing has to be performed over a longer period of time. In addition, two of four systems had conceptional problems to supply the subjects with pure O2 during inspiration. None of the tested systems was perfectly designed to serve in such emergencies.

Adult↗
PubMed2001

Laboratory diagnosis of heparin-induced thrombocytopenia type II after clearance of platelet factor 4/heparin complex.

Laboratory confirmation of heparin-induced thrombocytopenia (HIT) is limited by assay sensitivity. We investigated whether laboratory confirmation can be improved after antigen clearance by determining free antibody and combining the results of antigenic and biologic assays. Blood samples were collected over 5 to 6 weeks in 14 HIT patients. As an antigenic assay, the fluorescence-linked immunofiltration assay (FLIFA) was performed, and as a biologic assay, the carbon 14-labeled serotonin release assay was performed. At day 1 when heparin was stopped, 11 of 14 patients showed positive results in both assays; thus each assay had a sensitivity of 80%. The 3 patients with negative results seroconverted in one or both assays during the subsequent 7 days. Combining the positive results of the assays increased the sensitivity to 100% at day 7, regardless of whether the antigenic or the biologic assay was performed first. Both assays became negative in all patients within 5 to 6 weeks. The sensitivity of antigen and biologic assays in HIT patients increased to 100% after the time course of the heparin-induced antibody. We assume that in some HIT patients the free antibody can be detected after withdrawal of heparin and after clearance of the platelet-factor 4/heparin complex.

Aged↗
PubMed2001

Adult moyamoya disease with peripheral artery involvement.

We report the case of a young white woman in whom cerebrovascular moyamoya disease, which was associated with nonarteriosclerotic peripheral artery disease of the subclavian, iliac, and femoropopliteal arteries, was diagnosed by means of angiography. During 8 years of follow-up, the peripheral artery disease progressed, without any signs characteristic of systemic inflammation or vasculitis, leading to severe calf and arm claudication. Despite the absence of histologic confirmation, this observation strongly suggests that peripheral artery involvement may be a feature of moyamoya disease. To our knowledge, this is the first report of an association of classical cerebrovascular moyamoya disease with peripheral artery disease.

Adult↗
PubMed2001

Cutaneous reactions to anticoagulants. Recognition and management.

Anticoagulant-induced skin reactions appear as allergic or necrotic responses to vitamin K antagonists or heparins. Cutaneous allergy has been reported with danaparoid sodium and flush reactions have been seen with hirudins. The pathogenesis of the reactions differs between drugs. Generally, they occur between days 3 to 10 after the start of treatment, but may also occur later. In patients experiencing necrosis with a vitamin K antagonist, concomitant protein C deficiency, protein S deficiency or lupus anticoagulant has been described, whereas the precise mechanism of the other reactions is unknown. In patients with allergic reactions to heparins, cutaneous tests may help to identify alternative anticoagulants. Such a test cannot be performed in patients with skin necrosis. In patients with heparin-induced skin reactions danaparoid sodium may be used after negative intracutaneous testing in some patients and a hirudin may be used without testing in all patients. Heparin-induced skin necrosis has been reported to be mediated by immunologic mechanisms and to be associated with a high frequency of heparin-induced thrombocytopenia type II. Surgical excision of the necrosis may be required. If further anticoagulation is indicated in any patient, extreme caution has to be taken when restarting oral anticoagulants. Because a large number of anticoagulants available today, safe treatment of all patients experiencing anticoagulant-induced skin reactions is feasible.

Anticoagulants↗
PubMed2001

Improved laboratory confirmation of heparin-induced thrombocytopenia type II. Time course of antibodies and combination of antigen and biologic assays.

We studied whether laboratory confirmation of heparin-induced thrombocytopenia (HIT) can be improved after antigen clearance by determining free antibody and combining the results of an antigenic and a biologic assay. Blood samples taken over 40 days in 14 patients with HIT with thromboembolism underwent fluorescence-linked immunofiltration and the carbon 14-serotonin release assays. Of the 14 patients, 11 showed positive results in both assays at day 1 after stopping heparin. The 3 patients with negative results seroconverted in one or both assays during the subsequent 7 days. Combining the positive results of the assays increased the sensitivity from 85% at day 1 to 100% at day 7. Assay results became negative in all patients within 40 days. The platelet count normalized between days 2 and 9 after withdrawal of heparin. It is assumed that the free antibody can be detected after withdrawal of heparin and after clearance of the platelet factor 4-heparin complex in patients with HIT.

Aged↗