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Biomedical subjects

E Walter

Publications and source records attributed to E Walter.

At least 109 records · Page 6Linked to original sources
PubMed1987

Optimal experiment design for nonlinear models subject to large prior uncertainties.

Classical experiment design generally yields an experiment that depends on the value of the parameters to be estimated, which are, of course, unknown. Assuming that the model parameters belong to a population with known statistics, we propose to take the a priori parameter uncertainty into account by optimizing the mathematical expectation of a functional of the Fisher information matrix. This optimization is performed with a stochastic approximation algorithm that makes robust experiment design almost as simple as classical D-optimal design. The resulting methodology is applied to the choice of measurement times for multiexponential models.

Models, Theoretical↗
PubMed1986

Lung diseases after bone marrow transplantation. Results of a clinical, radiological, histological, immunological and lung function study.

The case histories of 72 subsequently treated patients - 44 with acute leukemia, 10 with chronic myeloid leukemia, 16 with severe aplastic anemia and 2 with neuroblastoma - were analyzed after bone marrow transplantation (BMT) with respect to pulmonary diseases. Thirty-eight patients suffered from a total of 51 pulmonary complications, which led to death in 20. Of 13 patients, 3 died of bacterial pneumonia, all of them during granulocytopenia; 2 of 6 patients died of fungal pneumonia and 2 out of 3 of a mixed bacterial-mycotic infection. Adult respiratory distress syndrome (ARDS) led to death in 2 patients. A granulocyte count under 500/microliter correlated significantly (P less than 0.002) with the fatal outcome of bacterial, fungal and ARDS pneumonia as well as with bronchitis. Viral pneumonia led to death in 8 of 9 patients; in each there was a significant correlation (P less than 0.05) with graft-versus-host disease (GvHD). Patients with repeated episodes of pulmonary illness had significantly more chronic GvHD (P less than 0.05); several of these patients displayed a reduction in helper T cells and an increase in suppressor T cells in the peripheral blood. The natural killer (NK) cells were reduced and the percentage of activated NK cell level lay between 6% and 69%. B-cells were absent or deficient. These findings explain in part the absence of specific antibody reactivity. Five of these patients also contracted GvHD-associated obstructive bronchiolitis, which did not respond to therapy. Pulmonary infiltrates of unknown origin (including idiopathic interstitial pneumonia) occurred in 8 of the patients (11.1%), with a fatal outcome in 3 patients. Significant changes (P less than 0.05) in lung function after BMT appeared in the form of reduced vital capacity (VC) increased residual volume (RV) and an increase in RV expressed as the percentage of total lung capacity. Pulmonary diseases were the most common complication and cause of death in our patients after BMT.

Adolescent↗
PubMed1986

[X-ray diagnosis of thoracic aorta ruptures].

One hundred and twenty-two patients were examined in order to diagnose, or for follow-up of, acute or chronic traumatic rupture of the thoracic aorta; sixty-two had arterial angiography, thirty-three had intravenous digital subtraction angiography, thirty-one had computer tomograms and seventeen were examined by ultrasound. In addition, plain films were evaluated in forty-two cases. The value of these methods in diagnosing acute or chronic aneurysms is analysed and discussed. Arterial angiography was the best method for acute aneurysms, whereas in the sub-acute and chronic stages CT and DSA are indicated.

Adolescent↗
PubMed1986

[Long-term observation of a case of intravenous injection of elemental mercury].

Elementary mercury is usually intravenously injected with suicidal intent. It is floated to the heart and lungs but is also deposited in the abdominal organs. Case histories presented in the literature so far have been followed up clinically and roentgenologically for up to three years. We report one patient attempting suicidal mercury injection, whom we were able to follow up for 10 years. It could be demonstrated that quite in contrast to former suggestions elementary mercury is dissolved and oxidised in the body. Chronic poisoning with mercury compounds causes continuing damage, particularly to the kidneys. Apart from that question, the element's pattern of spread within the body, toxicological issues, particular pathologic anatomic changes, their demonstrability on X-ray films and their clinical relevance are all discussed in this paper.

Adult↗
PubMed1986

Intracavitary chemotherapy with activated cyclophosphamides and simultaneous systemic detoxification with protector thiols in Sarcoma 180 ascites tumor.

Activated cyclophosphamides such as 4-sulfoethylthiocyclophosphamide (mafosfamide) are suitable for a local intracavitary chemotherapy, whereas cyclophosphamide requires a metabolic activation. Mafosfamide administered i.p. in mice was less toxic (50% lethal dose, 640 mg/kg) than its i.v. application (50% lethal dose, 480 mg/kg). A further remarkable reduction of toxicity with an increase of the 50% lethal dose of mafosfamide to 1500 mg/kg was obtained by the simultaneous i.v. application of the protector thiol cysteine (mafosfamide:cysteine ratio, 1:5 on molar weight basis). In comparison with the i.v. injection of mafosfamide, the local i.p. application resulted in a 20 times higher concentration versus time product of peritoneal drug levels. The molar ratio of sulfhydryl groups to activated cyclophosphamide (resorbed from the peritoneal cavity) remained high in blood. Therapy studies on Sarcoma 180 ascites tumor of mice revealed that the coadministration of cysteine i.v. in mafosfamide i.p. treatment is superior to mafosfamide i.p. application alone. On the contrary, the simultaneous i.p. application of cysteine is accompanied by a loss of antitumor efficacy. The regimen of local i.p. chemotherapy with activated cyclophosphamide and simultaneous systemic detoxification by an appropriate thiol allows the reduction of the systemic toxicity of treatment without influence on the cancerotoxic activity at the site of local injection and the exposing of the intraabdominal tumor to a much higher concentration of the cytostatic agent.

Animals↗
PubMed1985

[Reconstructive interventions following femoral fractures].

The complex and simple fractures seen in polytrauma patients after initial treatment sometimes show signs of poor setting and non-union with possible unfavourable functional consequences making reconstructive surgery necessary. In this report characteristic posttrauma problems and reconstructive surgery of the proximal femur, the femoral shaft and the distal femur are discussed. Possibilities other than prothesis or joint fusion, especially in the hip or knee joint, should be considered.

Bone Plates↗
PubMed1984

[Conventional roentgen diagnosis and computed tomography of the temperomandibular joint in myoarthropathy].

Clinical utilization of the high resolution, thin-slice CT (slice thickness: 1 mm) makes it possible to systemize the bony structure changes of the joint correlated with disfunctions. Using this technique total evaluations of this complex can be made. In patients suffering from myoarthropathy, the partially typical changes in both the functional anatomy, as well as in form, structure and topography of specific regions of the joint can be viewed objectively. The alteration process of the temporomandibular joint is considered causal in connection with muscular disfunctions, which often lay the foundation for chronic pain conditions in the regions of the face and head. The broad spectrum of conventional radiographic techniques documents, on one hand, the extremely unfavorable anatomy of the temporomandibular joint with regard to radiography. On the other hand, it also implies a certain amount of diagnostic uncertainty in this region. Comment is made concerning the informational value as well as the limits of the most important radiologic techniques. It is of utmost importance to evaluate the radiographic findings of the temporomandibular joint in myoarthropathies with a clinical functional analysis, which is easy to carry out.

Humans↗