Biomedical subjects
Publications and source records attributed to R Steffen.
The clinical and histologic features in 17 ovarian dysgerminomas from the files of the Institute of Pathology and University Women's Hospital, Zurich, have been reviewed. The intensity of lymphocytic infiltration displayed by the tumor tissue was quantitatively assessed and proved of prognostic significance, heavy lymphocytic infiltration being associated with a more favourable prognosis.
In the extracellular space of the tissue of the sponge Geodia cydonium, circular proteid particles are found which carry as subunits the aggregation factor and a series of glycosyltransferases. Using the technique of velocity sucrose gradient centrifugation, the sedimentation coefficient (S020,w) of the particle-monosomes was determined to be 90. By means of the Svedberg equation a molecular weight of 1.3 . 10(8) daltons could be estimated. The monosomes aggregate in the presence of Ca2+ to higher complexes via disomes, trisomes, and pentasomes. The complexes can be redissociated by dodecyl sulfate but not by EDTA. During the Ca2+-mediated self-aggregation, the particles lose their biological activity with respect to their aggregation promoting function.
The pharmacological properties of difenoxin hydrochloride, a meperidine derivative exerting antidiarrheal effect, are presented. The drug is compared with related substances such as diphenoxylate hydrochloride and loperamide. In an open multicentre study including 259 patients with acute or chronic diarrhea of various etiology, difenoxin hydrochloride removed the complaints in 63--75% of the cases and improved them in some further 20%. Mild side effects were seen in 4% of the cases. In view of the necessity to obtain immediate therapeutic results such an antidiarrheal may be prescribed in cases of traveler's diarrhea despite certain doubts. However, the patients should be warned to see a doctor if certain symptoms appeared.
A survey on rate of illness among 10 500 tourists returning from the tropics and a control group of 1300 from the United States and Canada was performed by a questionnaire completed during the flight back to Switzerland. Only 25% from southern destinations, but 53% from North America, were never incapacitated during their travels. The vast majority of the illnesses were of no consequence, as was reflected by a low rate for bed confinement of 4% and 1% respectively. The most frequent symptoms in the tropics were diarrhea in 34% (mostly of short duration and mild degree), constipation in 14%, upper respiratory illness in 12% and insomnia in 11%. There were significant differences according to sex, age and tropical experience. The influence on pre-existing diseases was assessed. 7% of the tourists returning from the tropics were sick in the course of the year following the journey.
In a retrospective study 453 cases of amebiasis were analyzed with regard to duration, purpose, and location of the patients' stay abroad. Diarrhea and abdominal complaints were the predominating features of the history, but occasionally constipation was the only symptom. The patients usually had chronic intestinal amebiasis which was intermittently slightly dysenteric, rather than non-dysenteric as defined by the WHO. There were two cases each of ameboma and colonic stricture and three liver abscesses, one of which proved fatal after complicating peritonitis. Therapy with a tissue and a lumenal amebicide proved to be the most efficient combination, with a success rate exceeding 94% in the controlled cases.
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Between 1971 and May 1976 221 adult persons originating from the region of Zurich (Switzerland) developed acute viral hepatitis within the incubation period after a usually brief trip abroad. In those returning from European countries the ratio of HBsAg positive and negative infections was similar to that in the Canton of Zurich. From other continents the proportion of non-B hepatitis was 66-94%. On the basis of travel statistics the risk of this disease was assessed as highest in West Africa and Mexico; trekkers are especially exposed. The indication and dosage for immunoprophylaxis are discussed in detail.
The activities of the three known catabolic and the one anabolic polyadenylate enzymes have been determined in synchronized L5178y cells: endoribonuclease, exoribonuclease, 5'-nucleotidase and poly(A) polymerase (Mg2+-dependent). These four enzymes were found primarily in the nuclear fraction. The activity of poly(A) polymerase remains essentially constant during the transition from G1 to S phase. However, the poly(A) catabolic enzyme activities increase parallel with DNA synthesis; the endoribonuclease activity increases 4-fold during G1 to S phase, the exoribonuclease and the nucleotidase activities increasing 30-fold and 16-fold. During the S phase the poly(A)-degrading enzymes are far more active than the poly(A)-synthesizing activity of poly(A) polymerase. We conclude that in L5178y cells the poly(A)-degrading enzymes probably function in regulation of the post-transcriptional net-polyadenylation of heterogeneous nuclear RNA during the phase of DNA synthesis.
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The poly(A)-specific endoribonuclease IV produces oligo(A) fragments of a chain length of 10 AMP nucleotides. One enzyme molecule performs 1700 cleavages per min; the cleavages occur randomly. The endoribonuclease IV is a nuclear enzyme which is present in the oviduct of quails in a concentration of 40 000 enzyme molecules per cell. Poly(A) segments on mRNA are selectively hydrolyzed by endoribonuclease IV; the poly(A)-free part of the RNA is not affected. After incubation with the enzyme, a residual oligo(A) stretch of 5 AMP nucleotides remains on poly(A)-rich RNA. The endoribonuclease IV does not disintegrate the polyribosomal complex after incubation in vitro and the enzyme has also no influence on the translational capacity of a cell-free protein-synthesizing system.
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Formycin B inhibited growth of L5178Y mouse leukemia cells in concentrations of less than twice the concentration that inhibits cell proliferation at 50% by cytostasis; at higher concentrations (more than twice the 50% concentration mentioned), the cells were killed. In cells treated with the concentration that inhibits cell proliferation at 50%, the average cell volume did not change. The formycin B inhibitory effect on cell proliferation was reduced by coincubation with nicotinamide adenine diphosphate or adenosine. The biosyntheses of DNA,RNA, and protein in whole cells were sensitively inhibited by formycin B as checked by incorporation studies with radioactive precursors. In addition, the formation of polyadenosine diphosphoribose was reduced even with higher sensitivity; in particular the extent of adenosine diphosphate ribosylation of histone subfraction H1 was reduced. Formycin B has been shown to be an inhibitor for the polyadenosine diphosphoribose polymerase, isolated from oviduct nuclei of quails. Both the chromatin-bound and the soluble enzyme are inhibited competitively; the relative affinity (Ki/Km) of formycin B to the polyadenosine diphosphoribose polymerase is 1.5.
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