Biomedical subjects

U Walther

Publications and source records attributed to U Walther.

13 recordsLinked to original sources

PubMed2004

Risk and protective factors for sporadic basal cell carcinoma: results of a two-centre case-control study in southern Germany. Clinical actinic elastosis may be a protective factor.

BACKGROUND: There are very few data regarding sun exposure behaviour of patients with basal cell carcinoma (BCC) in central Europe. OBJECTIVES: A case-control study of patients with sporadic BCC was conducted to assess the risk of occupational and leisure-time sun exposure behaviour, precursor lesions for skin cancer and phenotypic factors on the development of sporadic BCC in Ulm and Dresden, Germany. METHODS: A comparison was made of 213 patients with BCC (128 from Ulm, 85 from Dresden; 103 men and 110 women; median age at diagnosis 69 years) and 411 controls (237 from Ulm, 174 from Dresden; 197 men and 214 women; median age 58 years). Crude odds ratios (ORs) and corresponding 95% confidence intervals for all of 64 possible risk factors revealed strong associations in 33 items. Selection of important risk factors was performed in a multiple logistic regression. RESULTS: For sporadic BCC, an increased risk was shown for persons with actinic cheilitis (OR 7.1), actinic keratosis (OR 2.7) and solar lentigo (OR 2.5). The only phenotypic factor indicating risk of sporadic BCC was hair colour, with a higher risk for red/fair than brown/black hair (OR 4.3). There was an increased risk for persons with BCC in first-degree relatives (OR 5.1) and those with sunburn 20 years before sporadic BCC was diagnosed (OR 3.6). Additionally, occupational ultraviolet (UV) exposure appeared to be a risk factor (OR 2.4). In contrast, clinical actinic elastosis showed a protective effect (OR 0.1). CONCLUSIONS: In contrast to earlier reports, clinical actinic elastosis turned out to be the only protective factor for sporadic BCC. A special relationship between wrinkling and BCC risk could not be shown. For basic research, future work should be aimed at elucidating further the different forms of collagen repair processes after intermittent and/or chronic UV exposure. The data strongly support the recommendation that a change in recreational UV exposure habits in individuals, and sunburn avoidance in particular, are necessary not only because of the increased long-term risk of melanoma, but also because of the risk of other skin cancers such as sporadic BCC.

Adult↗

PubMed2001

Limitations of using delta 18O for the source identification of nitrate in agricultural soils.

The stable isotopic composition (delta 15N and delta 18O) of nitrate was analyzed in two lysimeter field experiments in order to identify the conditions under which the dual isotope approach can be applied to identify the main source of nitrate in agricultural soils. The first field experiment involved six lysimeters beneath fields that had been fertilized for 10 yr with the same type of fertilizer (NH4NO3; delta 15N = +1.2@1000, delta 18O = +18.6@1000). The isotope ratios of NO3- in the leachate (delta 15N approximately 0@1000; delta 18O approximately +2@1000) could not be interpreted in a conventional way with either fertilizer or soil organic nitrogen as main sources. These results provided clear evidence for the microbial immobilization and subsequent mineralization and nitrification to NO3- (mineralization-immobilization turnover concept). This process masked the original oxygen isotope ratio of the fertilizer source during the summer when microbial activity was high. A second experiment involving the application of Ca(NO3)2 to three lysimeters during the winter confirmed that the dual isotope approach remains valid for the source identification of nitrate under conditions of low microbial activity. The study reveals the limitation of the dual isotope approach to characterize nitrate sources under biologically active conditions and the ability to quantify microbial processes when the main sources can be controlled.

Agriculture↗

PubMed2001

Biological clearance of TEGDMA in guinea pigs.

The excretion of the dental composite component triethylene glycol dimethacrylate (TEGDMA) in feces and urine in vivo and, using the pendular perfusion technique with segments of jejunum and colon, the biliary and enteric excretion in situ were investigated in anesthetized guinea pigs. In the in situ experiments guinea pigs (n = 4) received TEGDMA (0.02 mmol/kg body weight labelled with a tracer dose 14C-TEGDMA 0.7 kBq/g body weight) injected into the jugular vein. In the in vivo experiments guinea pigs (n = 4) received TEGDMA (+14C-TEGDMA; same dose as above) via a gastric tube. Urine and feces were collected for 24 h. In the in situ experiments organs were removed from the guinea pigs 60 min after the beginning of the experiment, and the 14C radioactivity measured. During the 60-min perfusion period the calculated amount of 14C radioactivity excreted into the total jejunum and colon was 0.9 +/- 0.2% and 1.9 +/- 0.1% of the dose administered, respectively (means +/- SEM). Of the 14C-TEGDMA dose, 3.7 +/- 0.2% was found in the bile. A significantly (P < 0.05) higher bile/blood concentration ratio was found 10 min after injection of TEGDMA as compared with the ratios at 20 to 60 min. The following 14C activities (percent of the dose) per total organ were found in guinea pigs (in situ experiment; means +/- SEM): 6.9 +/- 1.7 (muscle), 3.9 +/- 0.5 (kidney), 3.3 +/- 0.1 (skin), 1.4 +/- 0.1 (blood), and 1.2 +/- 0.1 (liver). The 14C activity in all other organs was < 0.4%. The total 14C recovery in all organs tested was 17.5 +/- 1.8%. Over 24 h the amounts of 14C activity excreted in the feces and urine were 0.5 +/- 0.1% and 14.7 +/- 1.8% of the dose administered, respectively (means +/- SEM). The following 14C activities (percent of the dose) per total organ or contents of organs were found (means +/- SEM): 1.4 +/- 0.3 (liver), 0.8 +/- 0.3 (muscle), 0.5 +/- 0.1 (skin), and 0.5 +/- 0.1 (contents of cecum). The 14C activity in all other organs was < 0.2%. The total 14C recovery in all organs tested was 3.9 +/- 0.9%. In a second series of in vivo experiments exhaled air from the animals was captured during the 24-h experimental period. Of the administered dose, 61.9 +/- 4.6% of the 14C (means +/- SEM; n = 4) was exhaled as 14C-carbon dioxide. The results indicate a rapid clearance of 14C-TEGDMA and/or 14C-TEGDMA metabolite(s) from the organism and exhalation is the major route of elimination.

Animals↗

PubMed2001

Cytotoxicity of dental composite components and mercury compounds in pulmonary cells.

The cytotoxic potentials of the dental composite components triethyleneglycoldimethacrylate (TEGDMA) and 2-hydroxy-ethylmethacrylate (HEMA) as well as mercuric chloride (HgCl2) and methyl mercury chloride (MeHgCl) were investigated. Proliferating A549 and L2 cell monolayers were cultured in the absence or presence of composite components or mercurials. Twenty-four hours later the tetrazolium salt XTT (sodium 3'-[1-phenyl-aminocarbonyl)-3,4-tetrazolium]bis(4-methoxy-6-nitro)benzenesulphonic acid) was added. Formazan formation was quantified using a microtiter plate reader. EC50 values were obtained as half-maximum-effect concentrations from fitted curves. EC50 values were in A549 cells (mean values +/- standard deviation; n = 12; micromol/l); HEMA 8854+/-1882; TEGDMA 1821+/-529; HgCl2 41+/-7 and MeHgCl 27+/-3. EC50 values in L2 cells were: HEMA 191+/-28; TEGDMA 112+/-16; HgCl2 25+/-6 and MeHgCl 8+/-6. All tested substances induced a dose-dependent loss of viability in A549 and L2 cells after 24 h. The EC50 values of both mercurials were significantly (p < 0.05) lower compared to the values of both composite components. TEGDMA was about 5-fold (A549 cells) and about 2-fold (L2 cells) more toxic compared to HEMA. It is to be assumed that the risk of lung cell damage by dental composite components is even more unlikely.

Acrylic Resins↗

PubMed2001

Distribution and excretion of TEGDMA in guinea pigs and mice.

The monomer triethyleneglycoldimethacrylate (TEGDMA) is used as a diluent in many resin-based dental materials. It was previously shown in vitro that TEGDMA was released into the adjacent biophase from such materials during the first days after placement. In this study, the uptake, distribution, and excretion of 14C-TEGDMA applied via gastric, intradermal, and intravenous administration at dose levels well above those encountered in dental care were examined in vivo in guinea pigs and mice as a test of the hypothesis that TEGDMA reaches cytotoxic levels in mammalian tissues. 14C-TEGDMA was taken up rapidly from the stomach and small intestine after gastric administration in both species and was widely distributed in the body following administration by each route. Most 14C was excreted within one day as 14CO2. The peak equivalent TEGDMA levels in all mouse and guinea pig tissues examined were at least 1000-fold less than known toxic levels. The study therefore did not support the hypothesis.

Animals↗

PubMed1998

Marinesco Sjögren syndrome with rhabdomyolysis. A new subtype of the disease.

Four children from two families with characteristics of Marinesco-Sjögren syndrome (congenital cataract, ataxia) are presented. All children had clinical and neurophysiological signs of a demyelinating polyneuropathy. Three of them developed acute rhabdomyolysis with marked weakness and CK levels of up to 40,000 U/I following a viral infection. In all children CK levels returned to normal within two weeks. Symptoms were recurrent in one of the children and resulted in a severe disability. In two other children recovery of motor function took about a month following the first attack. Metabolic disorders of the muscle were excluded by pathobiochemical examination of a muscle biopsy in one of the children. In conclusion, acute rhabdomyolysis can occur as a neuromuscular complication of Marinesco-Sjögren syndrome.

Child↗

PubMed1997

Are we ready to replace dimercaprol (BAL) as an arsenic antidote?

1 Dimercaprol (BAL), 2,3-dimercaptopropanesulphonate sodium (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) are effective arsenic antidotes, but the question which one is preferable for optimal therapy of arsenic poisoning is still open to discussion. Major drawbacks of BAL include (a) its low therapeutic index, (b) its tendency to redistribute arsenic to brain and testes, for example, (c) the need for (painful) intramuscular injection and (d) its unpleasant odour. 2 The newer antidotes DMPS and DMSA feature low toxicity and high therapeutic index. They can be given orally or intravenously due to their high water solubility. While these advantages make it likely that DMPS and DMSA will replace BAL for the treatment of chronic arsenic poisoning, acute intoxication-especially with lipophilic organoarsenicals-may pose a problem for the hydrophilic antidotes, because their ionic nature can adversely affect intracellular availability. 3 This article focuses on aspects dealing with the power of BAL, DMPS, and DMSA to mobilize tissue-bound arsenic in various experimental models, such as monolayers of MDCK (= Madin-Darby canine kidney) cells from dog kidney, isolated perfused liver from guinea-pigs, and perfused jejunal segments from rat small intestine. 4 The results show that hydrophilic DMPS and DMSA may fail to rapidly and completely remove arsenic that has escaped from the extracellular space across tight epithelial barriers. However, owing to their low toxicity, which allows larger doses to be applied, and the potential modification of their pharmacokinetics by means of inert oral anion-exchange resins, DMPS and DMSA may advantageously replace BAL whenever intervention time is not critical. With severe intoxication by organic arsenicals, when the point-of-no-return is a limiting factor, BAL may still have a place as an arsenic antidote.

Animals↗

PubMed1991

The application of knemometry in renal disease: preliminary observations.

Short-term lower leg length was measured longitudinally using a high-precision device called a knemometer in 11 children with chronic renal failure and 12 normal children. The method has a high accuracy (mean standard error 0.13 mm) and may prove useful for prediction of long-term total body growth. Its application in renal patients undergoing corticosteroid, growth hormone (GH) and erythropoietin (EPO) therapy is documented. GH was shown to improve lower leg growth in an adolescent who already had passed the maximum of his pubertal spurt. EPO treatment produced no consistent increase of short-term growth.

Adolescent↗

PubMed1989

Myeloablative conditioning for marrow transplantation in myelodysplastic syndromes and paroxysmal nocturnal haemoglobinuria.

Paroxysmal nocturnal haemoglobinuria (PNH) and myelodysplastic syndromes (MDS) are disorders of pluripotent stem cells resulting in haematopoietic insufficiency which can be cured by marrow transplantation. The extent of myeloablative conditioning necessary for elimination of the non-malignant and premalignant clones is not known. We report our results of marrow transplantation with and without myeloablative conditioning in two patients with PNH and seven patients with MDS. Conditioning was not used in a patient with PNH and a monozygotic twin as donor. In this patient the disease remained unchanged. Myeloablative treatment with busulphan (BUS) in addition to immunosuppression with cyclophosphamide (CY) was used for conditioning in a patient with PNH and a 2-year-old boy with chronic myelomonocytic leukaemia (CMML). Fractionated total body irradiation (FTBI) and CY was used in six patients with refractory anaemia with excess of blasts (RAEB) and RAEB in leukaemic transformation (RAEB-T). Haematopoiesis was fully restored in all patients conditioned with myeloablative treatment except for a patient in leukaemic transformation with myelofibrosis and a HLA-DR-incompatible donor. Chimerism was complete in all patients except for the 2-year-old boy conditioned with BUS and CY. Our results and those reviewed in the literature indicate that myeloablative conditioning with either BUS or FTBI is advantageous for marrow transplantation in PNH and MDS.

Adult↗

PubMed1985

[Cell membrane differences between malignant and nonmalignant cells].

Malignant cells possesses an electric surface charge differing from their healthy counterparts. In many cases they exhibit increased electronegativity. We incubated blood or bone marrow with heparin--a polyanion--and subsequently stained the cells with a fluorochrome. In healthy subjects or patients with non-malignant disease heparin was found to attach closely to the cell surface, visualised through fluorescence. In a variable number of malignant cells heparin did not attach to the cell surface. Electrostatic repulsion of the negative heparin molecule through the increased negativity of the malignant cell is discussed as an explanation of this finding which can be corrected/inhibited by neuraminidase incubation.

Blood Cells↗

PubMedDate not supplied

Relapse and clonal disease in children with aplastic anemia (AA) after immunosuppressive therapy (IST): the SAA 94 experience. German/Austrian Pediatric Aplastic Anemia Working Group.

Since the introduction of combined immunosuppressive therapy (IST) into management of aplastic anemia (AA) in childhood response and probability of survival improved. In contrast to bone marrow transplantation (BMT), however, patients after IST are not considered cured as high rates of relapse and development of clonal disease demonstrate. From 11/93 to 9/97 114 children (65 m, 49 f; median age 9.5 y.) from 37 centers in Germany and Austria were registered in the SAA 94 study. 86 patients lacking a matched sibling donor received IST. Most of the patients suffered from very severe (VSAA: PMN < 200/microliter) or severe AA (SAA: PMN < 500/microliter). All patients were treated with combined IST consisting of ALG and Cyclosporin A (CSA). VSAA and SAA patients were additionally treated with G-CSF. Therapy response was evaluated at day 112, after 6, 12 and 18 months. 8/86 patients died, the probability of survival being 87% after 4 years. At d 112 61% of evaluable patients became independent of transfusions (IST response: CR + PR), 13% with normal blood counts (CR). After 6 months 33% showed CR. At 12 and 18 months response improved to 74% resp. 80%, 39% resp. 55% CR. The best response was achieved in the subgroup of VSAA with 90% (PR + CR) and 65% CR after 18 months. 4 patients developed AML 3-19 months after the beginning of IST. In 2/4 pts. an aberrant clone (-7; 5q-) could be detected retrospectively in BM at diagnosis of AA. 3 nonresponders developed chromosomal aberrations (+19; -7, +12; +8) after 4, 12 and 16 months without morphological signs of AML or MDS. Overall 11 relapses occurred at a median time of 12 months (range 5-27 months) after the beginning of IST. 2 of them relapsed under CSA therapy, 2 under tapering of CSA and 7 after cessation of CSA. 7 patients responded again to CSA monotherapy. Overall response rate is 77% with a probability of event free survival (EFS) of 54% after 4 years regarding all complications mentioned as events.

Adolescent↗

PubMedDate not supplied

[Effect of chloroquine on polyanions].

Chloroquine forms complexes with polyanions as does the metachromatic dye pseudoisocyanine. This phenomenon can be used to show chloroquine binding to polyanions. It is shown spectrophotometrically that glycosaminoglycans form complexes with chloroquine more readily than with pseudoisocyanine. Moreover chloroquine abolishes fluorescence of glycosaminoglycan inclusion bodies in leucocytes of mucopolysaccharidosis patients. A woman of 34 suffering from mucopolysaccharidosis type I-S had such inclusion bodies in 19 out of 200 leucocytes examined before and in only two after a month of chloroquine treatment. In heparinized blood chloroquine induces clotting faster than does saline in control samples. This finding suggests inactivation of polyanions by chloroquine binding.

Anions↗

PubMedDate not supplied

[The adolescent psychiatric service in the Saxony free state and its contribution to health promotion].

The tasks of the Public Health Service with particular reference to children and teenagers in the German Federal Land of Saxonia are laid down by legislation enacted by the Ministry for Culture on health care in schools (30.7.92). It is the main task of health promotion in schools to prevent health disorders and disturbed development in children and teens. The following tasks must be performed, among others: medical examination before admittance to school and in the classes 2, 5 and 9; public hours of consultation; and statistical documentation. All the essential demands on modern public health service for children and teens are part of current legislation in Saxonia.

Adolescent↗