Modeling of the fate of radionuclides in urban sewer systems after contamination due to nuclear or radiological incidents.

After an accidental radioactive contamination by aerosols in inhabited areas, the radiation exposure to man is determined by complex interactions between different factors such as dry or wet deposition, different types of ground surfaces, chemical properties of the radionuclides involved and building development as well as dependence on bomb construction e.g. design and geometry. At short-term, the first rainfall is an important way of natural decontamination: deposited radionuclides are washed off from surfaces and in urban areas the resulting contaminated runoff enters the sewer system and is collected in a sewage plant. Up to now the potential exposure caused by this process has received little attention and is estimated here with simulation models. The commercial rainfall-runoff model for urban sewer systems KANAL++ has been extended to include transport of radionuclides from surfaces through the drainage to various discharge facilities. The flow from surfaces is modeled by unit hydrographs, which produce boundary conditions for a system of 1d coupled flow and transport equations in a tube system. Initial conditions are provided by a map of surface contamination which is produced by geo-statistical interpolation of γ-dose rate measurements taking into account the detector environment. The corresponding methodology is implemented in the Inhabited Area Monitoring Module (IAMM) software module as part of the European decision system JRODOS. A hypothetical scenario is considered where a Radiation Dispersal Device (RDD) with Cs-137 is detonated in a small inhabited area whose drainage system is realistically modeled. The transition of deposited radionuclides due to rainfall into the surface runoff is accounted for by different nuclide-specific entrainment coefficients for paved and unpaved surfaces. The concentration of Cs-137 in water is calculated at the nodes of the drainage system and at the sewage treatment plant. The external exposure to staff of the treatment plant is estimated. For Cs-137 radiation levels in the plant are low since wash-off of cesium from surfaces is an ineffective process.

Different approaches for modelling of sewer caused urban flooding.

The correct prediction of flooding in urban areas is an important challenge to secure the values and fulfil public regulations. Traditional sewer simulations deliver the basic information for a rudimental flood protection, but the interaction between sewer and surface runoff can only be considered by a bi-directional modelling. Therefore detailed information about the relevant structures on the surface is necessary, which can partially be delivered by airborne laser scan data. This data have to be refined to get as detailed information about the endangered areas as possible. But the plenitude of information leads to high requirements on computer capacity and performance. This paper shows different approaches to predict the sewer caused flooding in urban areas. The approaches have been checked on two testing areas in Germany and the developed tool will be implemented in a commercial software system soon. This approaches, which partially base on each other, make a stepwise refinement of the model and narrowing of the affected areas possible. The developed algorithms to thin the digital terrain model and the well proven method to parallelize the calculation on more than one processing units secure an effective calculating process.

The use of preoperative intra-aortic balloon pump in open heart surgery.

AIM: Intra-aortic balloon pump (IABP) therapy before open heart surgery has been suggested for ''high risk'' patients. METHODS: Records from patients undergoing open heart surgery at our institution between June 1999 and February 2002 were reviewed. Indication for IABP insertion was severely impaired left ventricular function, acute myocardial infarction (MI) or unstable angina. RESULTS: Fifty-five patients were included in the study: 41 male, 14 female, age 64+/-9 years. Fifty-one (92.7%) required coronary artery bypass brafting (CABG) alone or as a combined procedure, 2 (3.6%) required mitral valve surgery, and 2 (3.6%) needed more complex cardiac procedures. Thirty-two patients (58%) underwent emergency cardiac surgery and 11 patients (20%) suffered from acute preoperative MI. The overall 30 days mortality was 9%. Mean intensive care unit (ICU) stay was 6+/-8 days. Four patients (7.2%) developed postoperative renal failure requiring temporary hemodialysis. Three patients (5.4%) developed IABP related peripheral vascular complications. CONCLUSIONS: Perioperative morbidity and mortality is increased despite preoperative IABP, particularly in patients with acute MI. In contrast to studies not using this approach, preoperative IABP reduces morbidity and mortality of high risk patients. IABP related complications are low. Our data suggest that high risk patients profit from preoperative IABP therapy, however, prospective studies are needed to confirm these findings.

Long-term anticoagulation with recombinant hirudin in a patient on left ventricular assist device support.

We report on a 24 year old man with a Novacor left ventricular assist device (LVAD) who underwent long-term treatment with intravenous recombinant hirudin due to a heparin induced thrombocytopenia (HIT II) after suffering from an ischemic stroke.

Heart surgery in patients aged eighty years and above: determinants of morbidity and mortality.

Escalating medical costs, limitation of resources and the necessity to provide cost-effective medical care have created a need for systematic risk stratification and cost-benefit analyses in the background of an ongoing discussion. Results of heart surgery in octogenarians have been evaluated in a prospective single-center, study since 1990. 101 consecutive patients (55/ 101 = 54.5% female) aged 80 years and above (median: 81 years; interquartile range [IQR]: 80.0-82.5, total range [TR]: 80-92 years) undergoing open heart surgery at our institution between January 1990 and March 1996 were included into this prospective study. Prior to surgery, most patients were severely symptomatic being in functional NYHA classes either III (56.4%) or IV (31.7%). 61/101 (60.4%) patients underwent isolated coronary artery bypass grafting (CABG), 23 (22.8%) had aortic valve replacement (AVR), 14 patients (13.9%) had CABG combined with AVR or double valve replacement and 3 (3.0%) had mitral valve repair. Follow-up (median: 23.0 months. IQR: 10.5-39.0, TR: 1-72) was focused on long-term morbidity and quality of life. The impact of preoperative and operative risk factors on morbidity and mortality was determined by uni- and multivariate statistical analysis. The 30-days overall mortality in this study was 7.9%. The postoperative course was uneventful for 27 (26.7%) of our patients. Univariate risk factors of postoperative mortality were: left main stem disease (p < or = 0.044), ejection fraction < 45% (p < or = 0.006), preoperative intensive care unit (ICU) (p < or = 0.002), urgent or emergency operation (p < or = 0.034). The only independent predictor of operative mortality was preoperative ICU-stay (p < or = 0.008). Significant risk factors for the number of postoperative complications in the multivariate analysis were: prior stroke (p < or = 0.04), diabetes mellitus (p < or = 0.02), New York Heart Association (NYHA) class IV symptoms (p < or = 0.002) and prolonged cross-clamping time (p < or = 0.001). Mean postoperative length of stay in the ICU was 3.9 +/- 3.9 days. Late morbidity was not related to postoperative complications. Cumulative survival was 87.9%, 79.5% and 72.9% at one, two or five years, respectively. After hospital discharge, 67/93 patients (82.8%) were in NYHA functional class I or II. Cardiac surgery in very elderly patients can be performed with acceptable operative risk and a favorable long-term outcome. The individual patient risk-profile including significant co-morbid conditions and severity of the heart disease predicts not only survival but the extent of perioperative morbidity.

Novacor LVAD bridge to transplantation in peripartum cardiomyopathy.

We report the case of a 22-year-old woman suffering from peripartum cardiomyopathy who was successfully bridged to cardiac transplantation with a Novacor left ventricular assist device (LVAD). Her course with the device is presented and emphasis is put on the size mismatch between the patient and the device, a fact with normally precludes the implantation of the Novacor LVAD.

Purification and Characterization of an l-Amino Amidase from Mycobacterium neoaurum ATCC 25795.

An l-amino amidase from Mycobacterium neoaurum ATCC 25795 responsible for the enantioselective resolution of dl-alpha-methyl valine amide was purified and characterized. The purification procedure included ammonium sulfate fractionation, gel filtration, and anion-exchange chromatography, which resulted in a homogeneous preparation of the enzyme with a native molecular mass of 136 kDa and a subunit molecular mass of 40 kDa. The purified enzyme displayed the highest activity at 50 degrees C and at pH 8.0 and 9.5. The enzyme was strongly inhibited by the metal-chelating agent 1,10-phenanthroline, the disulfide-reducing agent dithiothreitol, and the cysteine proteinase inhibitor iodoacetamide. The purified amino amidase showed a unique l-enantioselective activity towards a broad range of both alpha-H- and alpha-alkyl-substituted amino acid amides, with the highest activity towards the cyclic amino acid amide dl-proline amide. No activity was measured with dl-mandelic acid amide nor with the dipeptide l-phenylalanine-l-leucine. The highest catalytic efficiency (k(cat)/K(m) ratio) was measured with dl-alpha-allyl alanine amide, dl-alpha-methyl phenylalanine amide, and dl-alpha-methyl leucine amide.

Aortic valve replacement with cryopreserved pulmonary allograft.

Experimental as well as clinical data support the finding of using the pulmonary valve as a systemic semilunar valve. From January 1990 to December 1992, 89 patients received pulmonary cryopreserved allografts as aortic valve replacement. Sixteen subjects suffering from native or prosthetic valve endocarditis were included. Age ranged from 10 to 74 years. Sixty-five patients received isolated aortic valve replacement and 24 patients required additional surgical measures, such as coronary artery bypass graft, mitral valve reconstruction, replacement of the ascending aorta, supravalvular patch aortoplasty, ventricular septal defect closure, or myectomy. All operations were performed with normothermic bypass and cold cardioplegic arrest. Follow-up is maintained by visits to the outpatient clinic and echocardiographic assessment of the valve status every 3 months during the first year and every 6 months thereafter. There were four early and three late deaths. Four valves had to be removed: one intraoperatively and three 2, 4, and 24 months postoperatively. Echocardiographic assessment proved that gradients across the valve were low or absent. The majority of patients showed trivial or no aortic regurgitation during follow-up. No thromboembolic events have been observed and no new endocarditis occurred. Thus, event-free survival at 3 years is 87%. The results with pulmonary allografts have shown to be comparable to aortic allografts. Even in patients with acute native or prosthetic valve endocarditis, the use of cryopreserved pulmonary allografts has shown no adverse effects. We continue to implant cryopreserved pulmonary allografts in the aortic position. The long-term function of the valve, however, must be established, making continued evaluation of postoperative patients mandatory.

Engineering as a clinical tool for geriatric rehabilitation.

Of all age-groups, the over-60 group has the highest percentage of people with permanent, incurable, progressive handicaps. Clinical research during the past 14 years at the National Institute for Rehabilitation Engineering has shown that many elderly persons with permanent vision, hearing, speech, and mobility handicaps can be helped to be happier and more independent through a multidisciplinary team approach. The team should be led by physicians specializing in geriatric medicine and should include medical specialists, industrial engineers, efficiency and mobility experts, and task-performance trainers.

Spatial distribution of afferent information to the anterior lobe of the cat's cerebellum.

In the decerebrate cat discharges of Purkinje cells with simple and complex spikes as well as granule cell discharges in the c1-zone of lobules Va, b and c of the cerebellar anterior lobe were analyzed during a passive movement of the cat's forepaw. Penetrations were made 50 micrometers apart along the mediolateral and parasagittal directions, the depth never exceeding 500 micrometers. The response of the Purkinje cells to the climbing fiber input was surprisingly constant, while simple spike responses of the same cells showed a great variability to the same input. The variability between granule cell discharges recorded at a 50 micrometer distance from each other was similar to that of the simple spikes of the Purkinje cell. It is assumed that because of a patchy distribution of excited granule cells, two neighbouring Purkinje cells may receive a different information via their parallel fiber inputs. This difference is considered to be responsible for the great variability of their responses to mossy fiber inputs.