PubMed Health⌕ Search

Biomedical subjects

A Moritz

Publications and source records attributed to A Moritz.

At least 127 records · Page 7Linked to original sources
PubMed1994

Elective surgery for blunt cardiac trauma.

The cases of eight patients who underwent elective surgery for blunt cardiac trauma are presented. All but one experienced multiple trauma and the median Injury Severity Score was 26 (range, 18-59). A posttraumatic cardiac defect was diagnosed from 1 day up to 6.5 years (median, 3 weeks) after the accident. These included mitral regurgitation (n = 4), ventricular septal defect (n = 2), atrial septal defect with mitral regurgitation (n = 1), and ventricular aneurysm (n = 1). Elective cardiac surgery was performed from 4 weeks up to 12 years after the traumatic event (median, 18.5 months). A history of blunt chest trauma requires careful clinical follow-up supported by echocardiography in asymptomatic patients. Surgical therapy is performed according to standard techniques and the results are comparable with those of non-trauma surgery.

Adolescent↗
PubMed1994

[Comparison of surgical techniques and various suture materials for correction of aortic isthmus stenosis].

UNLABELLED: Clinical examination and Doppler ultrasound were performed in 31 children after repair of coarctation of the aorta. Median postoperative follow-up period was 4.5 years. The aim of our study was a comparison of different operation techniques and suture materials. In 16 infants subclavian flap repair had been performed using polydioxanone absorbable sutures (PDS) in 8 cases and polypropylene (Prolene) sutures in the other 8 cases. Resection and end-to-end repair had been carried out in 8 infants using PDS and in 7 using Prolene sutures. Doppler-echocardiographically derived gradients across the reconstructed aorta were significantly lower in infants operated with the subclavian flap technique (p < 0.05). The length of the arm on the side of the subclavian flap operation was shorter (median 1.2 cm), but there were no signs of ischaemic complications. Using PDS sutures the aortic arch and the aortic isthmus were each morphologically significantly wider in both operation techniques. Noninvasive two-dimensional echocardiography demonstrated good anatomical repair and no anastomotic aneurysm formation after aortic repair using polydioxanone. CONCLUSION: Regarding the doppler-echocardiographically derived gradients in the anastomotic region this intermediate follow-up study reveals better results using the subclavian flap technique; absorbable polydioxanone sutures favour normal growth of the anastomotic site without vascular complications.

Anastomosis, Surgical↗
PubMed1994

Cardioprotection by nifedipine cardioplegia during coronary artery surgery.

In a double-blind, placebo-controlled, randomized clinical study, the cardioprotective effect of nifedipine (Adalat, Bayer) as an adjunct to St. Thomas' cardioplegia was investigated in 24 patients undergoing coronary artery bypass grafting. Nifedipine at a dosage of 200 micrograms or placebo was added to each 1000 ml of St. Thomas solution, under strict light protection. ECG and haemodynamic data, including cardiac output measurements, serum calcium levels, creatine phosphokinase, (CK) CK-MB and lactate were measured during and after the operation. Additional cardioprotective effects were demonstrated in the nifedipine group by a significantly lesser reduction of the cardiac index after cardiopulmonary bypass and lower post-operative CK and CK-MB serum levels (P < 0.05). The incidence of ischaemia and cardiac arrhythmias was significantly higher in the placebo group on the post-operative ECG.

Arrhythmias, Cardiac↗
PubMed1993

Characterization of phosphatidylinositol-4-phosphate 5-kinase activities from bovine brain membranes.

Phosphatidylinositol-4-phosphate (PtdIns(4)P) kinase activity associated with bovine brain membranes, was released by NaCl treatment and partially purified by chromatography on phosphocellulose, phenylsepharose, Ultrogel AcA44, DEAE-cellulose and ATP-agarose. The final preparation contained a 6333-fold purified protein fraction with a specific activity of 171 nmol.min-1 x mg-1. Under conditions where this PtdIns(4)P kinase activity (PtdIns(4)P kinase activity b) did not bind to DEAE-cellulose, a PtdIns(4)P kinase activity purified earlier (Moritz, A., De Graan, P.N.E., Ekhart, P.F., Gispen, W.H. and Wirtz, K.W.A. (1990) J. Neurochem. 54, 351-354) does bind (PtdIns(4)P kinase activity a). Both enzyme activities specifically used PtdIns(4)P as substrate and phosphorylated the inositol moiety at the 5'-position. PtdIns(4) kinase activity a has an apparent Km of 18 microM for PtdIns(4)P whereas PtdIns(4)P kinase activity b has a Km of 4 microM. All other measured kinetic parameters (i.e., Km for ATP, Mg(2+)-dependence, pH optimum, activation by phosphatidylserine and inhibition by phosphatidylinositol 4,5-bisphosphate) were similar for both enzyme activities.

Animals↗
PubMed1993

Purification of B-50 by 2-mercaptoethanol extraction from rat brain synaptosomal plasma membranes.

Several methods have been described previously for the purification of the nervous-tissue specific protein kinase C substrate B-50 (GAP-43). In this paper we present a new purification method for B-50 from rat brain which employs 2-mercaptoethanol to release the protein from isolated synaptosomal plasma membranes. Most likely, 2-mercaptoethanol reduces disulfide bonds involved in the linkage of B-50 to the membrane. After washing the membranes with 100 mM NaCl to detach loosely bound proteins, B-50 is the major protein (and the only protein kinase C substrate) released by 0.5% 2-mercaptoethanol treatment. Further purification to apparent homogeneity is achieved by affinity chromatography on calmodulin sepharose. B-50 binds to calmodulin in the absence of calcium and specifically elutes from the column with 3 mM calcium. The procedures described is simple, rapid and highly suitable for large scale purification of B-50 from rat brain.

Animals↗
PubMed1993

Circulatory support with shock due to acute myocardial infarction.

Cardiogenic shock after acute myocardial infarction develops according to the amount of lost myocardium, function of remote myocardium, and the phenomenon of infarct expansion. Patients treated with mechanical support alone, without additional measures, have a mortality rate of 80%, the same as patients treated medically. Emergency angioplasty and emergency coronary artery bypass grafting can reduce mortality in certain subsets of patients to 40%. Patients with more severe shock and secondary organ dysfunction may be treated with mechanical bridging to transplantation with survival rates varying between 45% and 76%. Percutaneous support systems may be used to resuscitate a patient or to temporize, allowing time to perform diagnostic studies to determine if the patient is suitable for revascularization or heart transplantation. Intravenous enoximone may improve cardiac function as well and thus allow better decision making for further therapy.

Aged↗
PubMed1993

Six-year follow-up after heart valve replacement with the Edwards Duromedics bileaflet prosthesis.

The Duromedics Edwards valve (DE) was designed with a self-irrigating hinge mechanism to reduce the rate of thromboembolic complications. This report presents a prospective follow-up of patients after valve replacement with this prosthesis in a university hospital. Five hundred seven patients had DE prostheses implanted in the aortic (n = 268), mitral (n = 183) or aortic and mitral positions (n = 56). The perioperative mortality was 6.9%. Follow-up was 98% complete, comprising 2009 patient years for a mean follow-up of 48 months: (range 27-84). The actuarial freedom from complications is calculated as follows (linearized rates in parentheses): late mortality 81.0 +/- 2.3% (3.4%/patient year), thromboembolism 93.5 +/- 1.5% (1.1%/patient year), anticoagulation-related hemorrhage 89.5 +/- 2.0% (1.9%/patient year), prosthetic valve endocarditis 96.0 +/- 1.2% (0.7%/patient year), valve-related mortality 93 +/- 1.8% (1.5%/patient year), valve failure 89 +/- 2.0% (2%/patient year), treatment failure 88.0 +/- 2.0% (2.2%/patient year) and all valve-related morbidity and mortality 74.0 +/- 2.8% (5.3%/patient year). Two events of leaflet escape were observed in the study group (0.09%/patient year). Both patients were reoperated successfully. Mechanical hemolysis was subclinical in all cases. The DE shows a complication rate comparable to other modern mechanical valve prostheses. After solving the problem of durability, reconsideration of this valve is worthwhile due to its low risk of thromboembolic complications.

Aortic Valve↗
PubMed1993

Doppler sonographic evaluation of the Duromedics-Edwards bileaflet valve at five-year follow up.

In order to define normal flow characteristics at mid-term follow up, prospective Doppler echocardiographic studies were performed in 145 patients (mean age 49.3 years) with Duromedics-Edwards bileaflet valve prostheses (76 aortic, 55 mitral and 14 double aortic and mitral) at a mean interval of 5.2 years following operation. All patients had clinically normal prosthetic valve function and no clinical or radiographic signs of heart failure. None of the patients had severely impaired left ventricular function as assessed by cross sectional 2D echocardiography. Mean peak velocity across prostheses in the aortic position was 2.8 +/- 0.5 m/sec, corresponding to a calculated instantaneous peak pressure gradient of 31.4 +/- 10.2 mmHg. Gradients varied inversely to valve size, although differences were significant only when comparing the 19mm and 21mm versus the 27mm valve (p < 0.05). In the mitral position the mean of peak velocity was 1.8 +/- 0.3 m/sec and pressure half time was 102 +/- 14 msec, representing a calculated mean orifice size of 2.2 +/- 0.5 cm2, with no significant difference between valves of different sizes. Paravalvular regurgitation was more common in the aortic than in mitral position (39% vs. 4%, p < 0.05), although in all cases it was mild (range less than one centimeter from prosthesis ring) and clinically insignificant. We conclude that normally functioning DE valve prostheses have a predictable range of Doppler echocardiographic parameters, although the individual variability of pressure gradients and effective valve area (in mitral valves) has to be emphasized. Nevertheless, the Duromedics Edwards valve shows good hemodynamic properties at mid-term follow up.

Adolescent↗
PubMed1993

In vitro and in vivo endothelialization of glutaraldehyde treated bovine pericardium.

In an experimental study, endothelial cell seeding on glutaraldehyde-fixed and detoxified bioprosthetic tissue, suitable for valve fabrication, was investigated in vitro. These findings were compared to spontaneous endothelial cell ingrowth on vascular grafts fabricated from the same materials. Special consideration was given to the quality of cell attachment with regards to improved shear stress resistance in the endothelial layer covering the bioprosthetic surface. On glutaraldehyde detoxified bovine pericardium, in vitro endothelial cell seeding resulted in uninhibited cell proliferation, but the cells were loosely bound to the underlying tissue. In vivo, endothelial cells grew spontaneously over the surface of vascular implants in direct contact with the bioprosthetic material. In contrast to standard fixed bovine pericardium, a significant decrease in thrombotic appositions could be observed. Cells exhibited intensive production of extracellular matrix, which renders the method of spontaneous in vivo cell ingrowth as the most promising approach for further research.

Animals↗
PubMed1993

Use of varicose veins as arterial bypass grafts.

Varicose veins are not generally used as arterial bypass grafts despite their physiological endothelial flow surface. The large, irregular diameter and the thin wall renders these veins inadequate. Experimental studies have shown that a considerable reduction in the diameter of veins can be achieved by external wrapping without the generation of obstructing folds of the vein wall. A Dacron mesh tube surrounding varicose veins was used as a bypass graft in 13 infrainguinal arterial reconstructions. Ligated larger side branches and connections of the mesh segments caused irregularities of the otherwise smooth flow surfaces. Ten grafts were patent after a mean follow-up of 17 months. Two grafts have remained patent despite severe outflow obstruction in one and proximal occlusion in the other; both underwent successful interventions. The antithrombogenic properties of these grafts were partly due to a marked increase of the vasa vasorum. Externally constricted varicose veins may be used as arterial bypass conduits with good intermediate-term patency.

Aged↗
PubMed1993

[Valve saving correction of aneurysms of the ascending aorta with aortic insufficiency or annular dilatation].

The current technique to correct aneurysms of the ascending aorta with incompetence of the aortic valve or dilatation of the aortic root is the implantation of a valved conduit. In many cases however structurally normal aortic leaflets are resected by this technique and patients are at the risk of complications due to mechanical heart valve prostheses and the necessary anticoagulation respectively. By resuspension of the aortic valve into the aortic prostheses similar to the technique used at implantation of homograft valves, competence of the valve can be restored and the dilatation of the aortic annulus can be prevented or even reduced. Our article describes the successful, valve sparing correction of an acute aortic dissection type A with dilatation of the aortic annulus in a 43 year old patient and in another patient with ascending aortic aneurysm with aortic insufficiency.

Adult↗
PubMed1993

[Significance of bone marrow cytology in the diagnosis of leukosis in dogs].

In the differential diagnosis of neoplastic diseases of blood cells or their precursors, cytological examination of bone marrow is a valuable diagnostic tool. Depending on the expected cell type, an aspiration followed by clinical-cytological examination, or a biopsy followed by histopathological examination is indicated. In all unclear cases of cytopenia, if blood parasites or a lymphatic leukemia without tumors are suspected or in myeloproliferative diseases, bone marrow cytology can provide the diagnosis. If the aspiration of bone marrow is not possible in spite of correct technique (punctiosicca), myelofibrosis must be suspected. The diagnosis is confirmed by bone marrow biopsy. In the most common form of leukemia in dogs, the lymphosarcomatosis, a bone marrow biopsy can be helpful in assessment of the prognosis.

Animals↗
PubMed1992

Phosphatidic acid is a specific activator of phosphatidylinositol-4-phosphate kinase.

The lipid dependence of phosphatidylinositol-4-phosphate (PIP) kinase purified from bovine brain membranes was investigated. In the assay used, PIP-Triton X-100 micelles containing the lipid to be tested were presented to the enzyme. Under these conditions, phosphatidic acid (PA) stimulated the enzyme activity in a concentration-dependent manner up to 20-fold when an equal molar ratio of PA to PIP was attained. Stimulation by PA was highly specific; other lipids including lyso-PA and dicetylphosphate had a relatively small effect. The activation by PA was completely suppressed by phosphatidylinositol 4,5-bisphosphate (PIP2). To investigate the effect of PA on PIP kinase activity in natural membranes, endogenous PA was generated in rat brain synaptosomal plasma membranes by incubation with phospholipase D. Subsequent phosphorylation with [gamma-32P]ATP yielded an enhanced labeling of PIP2 but not of PIP in these membranes. These results suggest that PIP kinase activity may be under control of PA levels in membranes. This may have important implications for the regulation of cellular responses by agonist-induced phosphoinositide turnover.

Animals↗
PubMed1992

Mesh tube--constricted varicose veins used as bypass grafts for infrainguinal arterial reconstruction.

Varicose veins are generally deemed inappropriate graft material for arterial reconstructions despite their physiologic flow surface because of their large and irregular caliber. Size reduction by threading such veins in constricting tubes may create bypass grafts of suitable caliber as long as redundant wall material does not cause stenoses. Sixteen human varicose veins (mean +/- SD, 13 +/- 3 mm diameter) obtained after stripping operations were inserted into Dacron mesh tubes of 6 mm internal diameter. Paraffin casts of the distended veins showed a size reduction of 6.9 +/- 2.6 mm. Wall material formed folds in only two veins. In both cases, diameter reduction was more than 10 mm. However, the folds did not result in significant stenoses. Mesh-constricted varicose veins were used as bypass material in 11 infrainguinal arterial reconstructions. All externally supported segments showed satisfactory size reduction without stenoses or folds. One graft occluded 2 months after surgery. Two patients had to undergo reoperation after 2 and 16 months, respectively. None of the complications could be attributed to the constriction of veins. The remaining grafts are patent and functional after a mean of 17 months (range, 6 to 42 months). Considerable size reduction by external wrapping of varicose veins is possible without adverse side effects. Such constricted veins were used successfully as bypass grafts for infrainguinal arterial reconstructions.

Aged↗
PubMed1992

The use of mesh-tube-constricted dilated or varicose veins as arterial bypass conduit.

In general, dilated and varicose veins are not used as arterial bypass grafts despite their physiological endothelial lining. A uniform small diameter may be achieved by inserting such veins into mesh tubes. To test the degree to which dilated veins can be constricted without forming folds, in-vitro and experimental investigations were performed before such composites were used for clinical reconstructive surgery. Ovine jugular veins with a diameter of 15 mm were inserted into 6 mm tubes. After casting in paraffin wax none of the specimens showed folds on the flow surface. In 12 sheep pairs of mesh-constricted jugular veins and native femoral veins were implanted as femoropopliteal bypass grafts. Six animals were killed at 6 months and 6 at one year. All bypasses remained patent and none showed signs of obstruction caused by folds or anastomotic hyperplasia at angiographic control. Intimal hyperplasia was significantly reduced from 416 +/- 143 microns in the midportion of native vein grafts to 231 +/- 76 microns (p = 0.0001 paired t-test) in constricted veins as well as at the anastomoses (358 +/- 256 microns vs. 180 +/- 73 microns; p = 0.008). Partially or totally mesh-tube-constricted varicose veins were used for infrainguinal reconstructions in 19 patients and for coronary revascularization in 3. All grafts showed an even calibration at control angiography. As constriction does not lead to internal folds, varicose or dilated veins may be used successfully as bypass grafts after insertion into mesh tubes. The external reinforcement reduces the intimal hyperplasia within the graft and also reduces anastomotic hyperplasia.

Aged↗