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Biomedical subjects

K Böcker

Publications and source records attributed to K Böcker.

13 recordsLinked to original sources
PubMed2002

Simulation of a nitrification control concept considering influent ammonium load.

Buchenhofen wastewater treatment plant of Wupperverband (650,000 p.e.) is currently being expanded for targeted nitrogen elimination. In view of the limited space available for extension, an optimized control concept is to be used in order to minimize the number of additional tanks required. This concept was investigated by dynamic simulation based on Activated Sludge Model No. 1. The investigations included a pure feedback control configuration and a configuration combining feedback und feedforward control, considering the influent ammonium load, for aeration. The results show that combined feedforward/feedback control has significant advantages over pure feedback control. In particular, this configuration allows a reduction in the effluent NH4-N peaks, which is especially important because of the low NH4-N limit of 5 mg NH4-N/L in a grab sample.

Computer Simulation↗
PubMed1989

Effects of nucleotides and divalent cations on phospholipase activity in Saccharomyces cerevisiae.

Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 microM. The inhibition by nucleotides in low concentrations is enhanced by divalent cations.

Acyltransferases↗
PubMed1987

Diagnosis of hypertrophic cardiomyopathies by non-ECG-gated cardiac computed tomography (CCT).

In order to study the significance of non-ECG-gated cardiac computed tomography (CCT) for the diagnosis of hypertrophic cardiomyopathies, the method was applied in 55 consecutive patients and the data were correlated with the echocardiogram. In a subset of 18 patients left and right heart catheterization was additionally performed, and in a subset of 17 patients, endomyocardial biopsy was performed. The CCT turned out to be an easily applicable, non-time-consuming method for obtaining a sectional visualization of the left and right ventricle. Regarding the septal thickness, there was an unexpectedly high correlation between CCT and echocardiogram (r = 0.9). The left ventricular deformity observed by echocardiogram and angiography in patients with hypertrophic cardiomyopathies corresponded well to that visualized by CCT, leading to a good differentiation between HOCM and HNCM (diagnostic specificity: 92% and 80%, respectively). It is concluded that the non-ECG-gated CCT seems to be a very helpful non-invasive method for diagnosing hypertrophic cardiomyopathies and differentiating between the obstructive and nonobstructive forms. From a clinical point of view, this may be important, mainly in patients in whom no clear-cut diagnosis is possible using previously applied non-invasive methods, including echocardiography. It may also be useful for follow-up studies, providing a sectional insight into the distribution of left ventricular hypertrophy.

Adult↗
PubMed1986

99mTc-diethyl-iodo-HIDA (JODIDA): a new hepatobiliary agent in clinical comparison with 99mTc-diisopropyl-HIDA (DISIDA) in jaundiced patients.

The new HIDA derivative, 99mTc-diethyl-iodine-HIDA (JODIDA), was compared with 99mTc-diisopropyl-HIDA (DISIDA) in 17 patients with jaundice by means of paired cholescintigraphic imaging studies. The following parameters were visually assessed: the extent of urinary tract visualization, biliary contrast and appearance time, and gallbladder visualization and appearance time. In the 6 patients with a total bilirubin level of between 19 and 66 mumol/l (1.1 and 3.9 mg/dl), both radiopharmaceuticals gave similar results except for the moderate visualization of the urinary tract with DISIDA in contrast to JODIDA. In the remaining 11 patients with a total bilirubin level between 102 and 1303 mumol/l (6 and 76 mg/dl). JODIDA showed significant advantages over DISIDA: nonvisualization of the urinary tract, stronger and faster biliary contrast, and better gallbladder visualization. JODIDA thus offered substantial diagnostic advantages over DISIDA in 8 of these patients. In 4 patients, the differential diagnosis of jaundice (intrahepatic or mechanical disorder) was possible with JODIDA, whereas DISIDA either could not visualize intestinal or gallbladder activity at all or could not differentiate it from the urinary tract. In one patient, JODIDA offered faster (18 h) diagnosis. In the remaining 3 patients, other, substantially false interpretations could be avoided through the use of JODIDA. Further clinical experience with JODIDA in more than 40 patients confirmed the results of this study. We concluded that JODIDA is of significant advantage over DISIDA in clinical situations such as total bilirubin level above 80-100 mumol/l (4.7 to 5.8 mg/dl), examination of small children and critically ill patients and suggestion of bile leakage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Results of coronary revascularization in occluded coronary arteries].

In a total of 82 patients (age 37-71 years) with an occluded left anterior descending artery (LAD) the results of coronary revascularization were evaluated 7 months postoperatively on average. In all patients the indications for revascularization was given by clinical symptoms (angina pectoris) or by prognostic reasons. In patients with multivessel disease. In patients with anterior wall infarction viable myocardium was proven by thallium-scintigram at rest and during exercise. 29 patients were evaluated by coronary angiography postoperatively, in 19 patients the angiograms of the left ventricle could be assessed quantitatively. Total patency rate was 76%, for the LAD 69%, for the circumflex artery 73% and for the right coronary artery 83%. The relatively low patency rate for the LAD was caused by an increased collateral flow to the occluded LAD and therefore by a significantly lower bypass flowrate measured during surgery. Angina pectoris improved markedly, 55% of patients had angina pectoris class III or IV versus 10% postoperatively. These changes were observed in all patients irrespectively of patency rate or occluded grafts to the LAD. Left ventricular volumes and ejection fraction did not change on average after revascularization. Only end-diastolic volume increased significantly in patients with an occluded graft to the LAD. There was a tendency of the end-systolic volume to decrease postoperatively in patients with complete revascularization or at least an open graft to the LAD. The results show a similar clinical improvement in these patients with occluded LAD as shown after "usual" revascularization in other patients. Preoperative coronary angiograms are helpful in judging the postoperative outcome of grafts to the occluded LAD.

Adult↗
PubMed1982

[The effect of disopyramide, mexiletine and propafenon after intravenous and oral administration on left ventricular function in the M-mode echocardiogram].

The effects of the antiarrhythmic drugs disopyramide (D), mexiletine (M), and propafenone (P) on left ventricular function after intravenous injection and after oral therapy of at least 48 hours, and of the combined oral application of D and M, were studied by M-mode echocardiography in patients with ventricular arrhythmias in whom antiarrhythmic therapy was indicated. The drugs were given in doses comparable in terms of clinical efficacy. The results showed that the three drugs had varying negative inotropic power. The intravenous injection resulted in a more pronounced cardiac depression than the oral therapy. The most significant decrease in left ventricular wall motion after intravenous and oral application was seen after D, the smallest negative inotropic effect after M. P caused a cardiac depression between these extremes. After the combined oral application of D and M the impairment of left ventricular function was more pronounced than after therapy with the single drugs.

Administration, Oral↗
PubMed1981

Selenium and myocardial infarction: glutathione peroxidase in platelets.

The activity of the selenoenzyme glutathione peroxidase (EC 1.11.1.9) was determined in platelets of 15 patients with acute myocardial infarction and 13 control subjects. The platelets of the patients had significantly lower activities of the enzyme (P(t) greater than 0.99). This may be related to the pathogenesis of the disease.

Adult↗
PubMed1981

[The diagnostic value of M-mode-, two-dimensional echocardiography, and computed tomography in comparison to the results of cardiac catheterization in the diagnosis of tumors of the heart (author's transl)].

12 patients with cardiac tumors (7 myxomas of the left, 2 of the right atrium, 2 ventricular, 2 intramural tumors and 1 epicardial cyst) were examined by M-Mode-(ME) and two-dimensional (2DE) echocardiography, computertomography (CT) and heart catheterization (HK) with angiography (A). The results were compared with intraoperative findings. There were no false negative results with 2DE and CT, but in 1 case the size of an intramural tumor was underestimated by 2DE. With ME all atrial myxomas were diagnosed, but 2 ventricular and 2 intramural tumors as well as the epicardial cyst were overlooked. Also with HK and A, the 2 intramural tumors and the epicardial cyst were not recognized well. The results indicate that the diagnosis of cardiac tumors can be made with great accuracy by noninvasive methods. The sensitivity of the single methods depends on the location of the tumors.

Adolescent↗
PubMed1981

[Holosystolic mitral valve prolapse and "SAM" after surgical treatment of hypertrophic obstructive cardiomyopathy (author's transl)].

In a 49-year-old male patient surgical treatment of hypertrophic obstructive cardiomyopathy (HOCM, clinical grade III, NYHA) by means of transaortic myotomy and myectomy was performed in November 1979. 6 months later the M-mode-echocardiogram revealed a distinct systolic anterior motion of parts of the mitral valve apparatus (SAM) as well as a marked holosystolic mitral valve prolapse (MVP). The two-dimensional echocardiographic examination demonstrated that the "SAM"-phenomenon was caused solely by chordae tendineae of the anterior mitral leaflet, while the prolapse was due to the posterior mitral leaflet itself.

Cardiomyopathy, Hypertrophic↗