Biomedical subjects
Publications and source records attributed to O Ahrens.
Causes, pathophysiology, diagnosis, therapy and a retrospective analysis of small bowel obstruction were reviewed. 85 patients were operated during a 5-year period. The etiology of obstruction were adhesions (45 cases), hernia (20 cases) and 20 other cases. The mortality rate for the series was 8%. The most important factor of prognosis is the early operative treatment.
Basic differences and similarities of flow and static cytophotometric instruments are viewed with regard to technical peculiarities and applicability in the fields of biology and tumor pathology. In flow systems, precision of the information concerning quantities of constituents is high, whereas precision of information concerning morphologic parameters is low. In static systems, morphologic identification by a trained operator can be used advantageously to classify any given cell interactively, thus replacing a large number of flow parameters. This is why the vast majority of automated static machines used in pathology are still more or less semiautomatic or interactive. Carefully performed specimen-adapted cell preparation procedures in which each step is strictly supervised, highly standardized staining methods, and internal controls are prerequisites in order to obtain reliable cytochemical results. In a number of human tumors with well-controlled cytopathologic and/or histopathologic and clinical data, quantitative cytochemical analysis has been demonstrated to provide diagnostic and prognostic information complementary to that obtained by conventional clinical and morphologic methods.
Hybridoma cell lines secreting monoclonal antibodies (Mab) directed against the products formed by reaction of alkylating N-nitroso carcinogens with DNA have been established by fusion of rat or mouse myeloma cells, respectively, with spleen cells of rats or mice immunized either with conjugates of various alkyl-ribonucleosides with suitable carrier proteins, or with alkylated DNA electrostatically complexed to carrier proteins. Due to their high affinity and specificity, some of these Mab detect very low amounts of the respective alkyl-deoxynucleosides (e.g., O6-methyl-2'-deoxyguanosine, O6-ethyl-2'-deoxyguanosine, O6-n-butyl-2'-deoxyguanosine, O6-isopropyl-2'-deoxyguanosine, O4-methyl-2'deoxythymidine, O4-ethyl-2'-deoxythymidine) and can be used in various types of immunoassays. With a competitive radioimmunoassay (RIA), specific DNA alkylation products can be quantitated in hydrolysates of cellular DNA, in body fluids, or in urine. The RIA is routinely applicable, reproducible, and sufficiently sensitive to permit the quantitation of femtomole amounts of modified nucleosides in small samples of DNA. When the alkyl-deoxynucleosides in question are separated from bulk DNA by high-performance liquid chromatography prior to analysis by RIA, very low levels of modification in DNA can be detected. The immuno-slot-blot (ISB), a noncompetitive solid-phase immunoassay, is more sensitive than the RIA. For analysis by ISB, alkylated DNA is heat-denatured and immobilized on nitrocellulose filters prior to exposure to the respective Mab and subsequent binding of a second (125I-labelled or biotinylated) antibody. In immunocytological analysis (ICA), the binding of Mab to alkyl-deoxynucleosides is visualized in individual cells by immunostaining of denatured nuclear DNA in situ (direct immunofluorescence; peroxidase-staining).(ABSTRACT TRUNCATED AT 250 WORDS)