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Biomedical subjects

K Krauth

Publications and source records attributed to K Krauth.

7 recordsLinked to original sources

Oxygen transfer into activated sludge with high MLSS concentrations.

In this report, tests on the impact of the sludge properties on the oxygen transfer at low and high solids contents are presented. Additional to the oxygen transfer tests, the activated sludge was intensively analysed to examine the changes of the alpha-factor in relation to the sludge properties (rheology, EPS, CST, etc.). The alpha-factor did strongly decrease in all sludge types at increasing MLSS or increasing viscosity, respectively. In the second test stage, the impact of the aeration system was examined in detail. For these tests, the same sludge from a membrane bioreactor was used throughout. Apart from the impact of the power density in the reactor and the specific air throughput, the main focus was on the economic efficiency of the examined systems in cases of high MLSS. It became apparent that up to solids contents of 18 g/l the fine-bubble aeration is the most economically efficient method.

Biomass↗

Sequencing batch reactor with submerged hollow fibre membranes for the biomass separation.

A method to reduce the cycle time of the SBR-process by utilising submerged membranes is described. The time necessary for the sedimentation of the activated sludge and the extraction of the clear-water phase takes up a major part of the entire cycle period within the SBR-process. By using membranes it is possible to start the clear-water extraction already during the reaction time. The time needed for the sedimentation of the activated sludge can be dispensed with altogether. The paper presents the initial results of a semi-technical test plant, with particular emphasis on the fact that the running of the SBR-plant did not lead to any problems with fouling or scaling. In cases of high solids contents, the oxygen input was below par; this, however, did not have any unfavourable impact on the nitrification.

Bacteria↗

Two types of TNF receptors are expressed on human normal and malignant B lymphocytes.

We analyzed the expression of the 75- and 55-kDa tumor necrosis factor (TNF) receptors on the surface of human normal and malignant B cells. Freshly isolated tonsillar B cells do not express detectable amounts of receptors. After 24 hr of stimulation with anti-IgM and low-molecular-weight (l.m.w.) BCGF, B cells express the 75-kDa receptor but not the 55-kDa receptor, but after 48 hr of stimulation both types of receptors are expressed. Three of 10 patients with B-chronic lymphatic leukemia or hairy cell leukemia (HCL) had a small population of TNF receptor positive tumor cells; after in vitro stimulation of tumor cells in 10/10 patients various patterns of 75- and 55-kDa TNF receptor expression were found. MAb UTR-1, which binds the 75-kDa receptor, inhibits the l.m.w. BCGF-induced [3H]thymidine incorporation of cultured tonsillar B cells and HCL cells. This may provide evidence that in B cells the 75 kDa TNF receptor molecule is functionally active.

Antibodies, Monoclonal↗

Topotecan in the treatment of refractory neuroblastoma and other malignant tumors in childhood - a phase-II-study.

BACKGROUND: The topoisomerase-I-inhibitor Topotecan (TPT) has shown a broad activity in the therapy of adult malignant diseases. In pediatric oncology TPT has been rarely used. METHODS: From 1/98 to 8/99 we conducted a multicenter phase-II-study of TPT (1.5 mg/m (2)/d in 30 min i. v. for 5 days every 21 days) in pediatric patients (pts) with malignant tumors refractory to conventional therapy (either second line or any relapse). PATIENTS: A total of 20 pts received 81 cycles. The 7 female and 13 male pts had a median age of 10.2 years at the beginning of the TPT therapy. RESULTS: The median number of administered TPT cycles was 4 with an interval of 23.5 days. The median administered TPT dose was 1.48 mg/m (2)/d. No complete responses, but 2 partial responses and 9 stable diseases were observed. In 9 pts the disease progressed. The mean duration until progression for SD was 130 and not different from PR with 131 days. The median cumulative TPT dose until progression in responders was 30 mg/m (2). For all study-pts the median overall survival time was 235 days with 1 pt. still alive. The main toxicity was hematological with anemia grade III/IV (10/42 % of all evaluable TPT cycles), neutropenia grade III/IV (49/18 %) and thrombopenia grade III/IV (35/36 %). Non-hematologic toxicity was mild with the exception of 4 cycles with infection grade III and 1 grade IV. No patient died of therapy-related complications. CONCLUSIONS: TPT as monotherapy has shown an antitumor activity in pediatric pts with various malignancies. Toxicity was mainly hematological and manageable. Further evaluation of TPT treatment is planned using combinations with other cytostatic drugs.

Adolescent↗

Bone marrow oedema and aseptic osteonecrosis in children and adolescents with acute lymphoblastic leukaemia or non-Hodgkin-lymphoma treated with hyperbaric-oxygen-therapy (HBO): an approach to cure? -- BME/AON and hyperbaric oxygen therapy as a treatment modality.

BACKGROUND: There is a striking need for additional therapies of bone marrow oedema (BME) and aseptic osteonecrosis (AON) in paediatric oncology patients. Hyperbaric oxygenation (HBO) therapy used in the treatment of osteoradionecrosis is demonstrated effectiveness. Aim of this retrospective analysis was to investigate whether HBO-therapy might lead to subjective as well as objective effects in the treatment of BME and/or AON in paediatric oncology patients with acute lymphoblastic leukaemia (ALL) or Non-Hodgkin lymphoma (NHL). PATIENTS AND METHODS: Between 11/1988 and 01/2001 27/291 (9.3 %) patients with ALL or NHL were diagnosed with a BME and/or AON in the Clinic for Paediatric Oncology, Haematology, and Immunology at University of Dusseldorf. 19/27 patients were submitted to HBO-therapy. Patients received average 45 HBO-treatments per patient (min. 13, max. 80 treatments). The affected regions were re-evaluated with MRI for radiological extent of lesions every 3 months. Pain in its intensity and localisation was serially recorded during HBO-therapy as key symptom in 11 of 19 patients. RESULTS: 27 patients (15 females, 12 males; mean age at diagnosis of malignancy 8.2 +/- 4.7 (SD) years, range 7 months to 16 years) presented with 138 lesions. 133/138 lesions were localised in the lower extremities. At diagnosis of BME and/or AON, 78/133 lesions were shown in females and 55/133 lesions in male. Girls < 10 years predominantly presented BME (33 BME vs. 6 AON), girls aged > 10 years predominantly offered AON (28 AON vs. 11 BME). BME was more often exhibited in boys < 10 years (34 BME vs. 10 AON) and rarely in boys > 10 years (4 BME vs. 6 AON). 11 patients treated with HBO-therapy were serially evaluated for pain intensity throughout their HBO-therapy courses by visual analogue scale (VAS) assessment. During the first 15 treatment courses the HBO-therapy a clear-cut reduction of pain was observed. The mean pain score before the first HBO-treatment unit was 2.4 +/- 2.7 (X +/- SD), decreased before the fifth to 1.6 +/- 1.7 and prior to the 35 (th) and 40 (th) HBO treatment to 0. Girls < 10 years treated with HBO showed an increase of BME (31 --> 46) and declining AON numbers (6 --> 2). Girls > 10 years with and without HBO-therapy showed decrease of BME lesions (7 --> 4 vs. 4 --> 0), whereas AON increased in the HBO-treated group (28 --> 29) as well as the non-treated group (0 --> 4). Males < 10 years showed an increase in BME lesion numbers despite HBO intervention (24 --> 26). The AON lesion numbers dropped in parallel (6 --> 3). Male patients not treated with HBO showed constant numbers of BME (11-->11) and a decreased numbers of AON (4 --> 2). All differences are statistically not significant. CONCLUSIONS: Children and adolescents diagnosed with ALL or NHL have a risk for accruement of BME and/or AON irrespective of the age, with an almost exclusive involvement of the lower extremities. Lesions of pedal bones and ankle joints predominantly affect children < 10 years. Lesions of knee and hip joints predominantly affect children > 10 years. In children < 10 years of age we demonstrate declining AON numbers and conversion of AON to BME thereby implicating possible beneficial effect of HBO in such patients. HBO failed to show beneficial effect on BME whether by preventing new lesions or by improving existent lesions in children > 10 years.

Adolescent↗

[Experimental principles of therapy-oriented pathogenetic classification of aplastic anemia in childhood].

Growth and differentiation of hematopoietic progenitor cells is regulated by a complex network of stimulatory and inhibitory cytokines. Bone marrow failures can be due to a decrease of stimulators or an increase of inhibitors. T cells produce both, hematopoiesis stimulating and inhibiting cytokines. Therefore, a role of T cells in regulating hematopoiesis can only be assumed if the gene expression of these antagonistic acting cytokines can be differentially induced in T cells. To establish a model of selective cytokine induction, we investigated the induction of IFN gamma as inhibitor and GM-CSF as stimulator of hematopoiesis in T cells. Our results showed that IFN gamma mRNA accumulates in T cells which have been pre-activated via the signal transduction unit CD3, but not in unstimulated T cells. This accumulation depends on the expression of the high affinity IL2 receptor which is including the IL2 receptor alpha-chain (IL2R alpha, CD25). In a study on children with constitutional (CAA) versus acquired aplastic (EAA) anemia, we investigated the relevance of this model for the pathogenesis of aplastic anemia in childhood. We compared the following parameters: 1. Incidence of hematopoietic progenitor cells and cloning efficiency, 2. activation status and IL2R alpha expression of bone marrow T cells, 3. T cell cytokine expression profile. Our results show: 1. The relative incidence of bone marrow progenitor cells is decreased in children with CAA and normal in children with EAA. 2. Clonogenic growth of hematopoietic progenitor cells is suppressed in children with EAA.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Aplastic↗