Biomedical subjects
Publications and source records attributed to F Cramer.
We describe the convenient synthesis of thymidine cyclic 3', 5'-phosphorofluoridate 6, which is superior to that previously reported. Our procedure is based on a sequence of reactions utilizing 3 as the key substrate. Similar sequence of reaction leads to the sulfur analogues of 6 the thymidine cyclic 3',5'-phosphorofluoridothioate 7.
Yeast tRNAPhe and tRNATyr were reacted with the fluorescent reagent pyridoxal-5'-phosphate and the modified tRNAs were analysed with respect to the number and position of modified nucleosides and with respect to aminoacylation. a) Following the intrinsic fluorescence of pyridoxal-5'-phosphate, the treatment of tRNATyr with increasing amounts of pyridoxal-5'-phosphate revealed about 50 mol or reagent or a even higher number bound per one mol of tRNATyr. After borohydride reduction (in order to stabilize the linkage) of this modified tRNATyr and purification with reverse phase chromatography a modified tRNATyr was obtained carrying about 2 mol of the reagent. b) Both tRNATyr and tRNAPhe treated with pyridoxal-5'-phosphate and reduced exhibited almost unchanged aminoacylation as compared to the unmodified tRNAs. c) Pyridoxal-5'-phosphate treated and reduced tRNAPhe and tRNATyr were digested with ribonuclease T1 and the resulting oligonucleotides were separated. However, no fluorescent oligonucleotide and no difference to an oligonucleotide pattern obtained from unmodified tRNA were observed. Thus, pyridoxal-5'-phosphate might have been bound to the highly purified yeast tRNAPhe and tRNATyr samples either via an unstable linkage or not covalently. This result is controversial with respect to the specific reaction of pyridoxal-5'-phosphate with unfractionated tRNAs from colon carcinoma and tRNAs from E. coli as reported in the literature.
The specific activities of 17 aminoacyl-tRNA synthetases in liver, lung, heart, spleen, kidney and small intestine of old female normal and leukemic (reticulum-cell sarcoma, type A) mice have been monitored. No difference appears for lung, heart and kidney; small increases with varying particular changes for liver and marked increases in spleen and small intestine of the tumor bearing mice have been found, following a similar pattern. This finding suggests a coordinated adaptation to modulation of the requirements of protein synthesis imposed by histiocytic sarcoma.
Lectins are carbohydrate-binding proteins of non-immune origin that can be assayed as agglutinins. They are potential mediators in recognitive processes and cell adhesion by interaction with glycoconjugates. These functions are areas of particular relevance to tumor growth and metastatic spread. The presence of lectins in tumors has first been inferred by histochemical and cytological methods. The biochemical analysis for lectins with various specificities reveals differences in the lectin profile between tumors of different classes (eg, mammary adenocarcinoma, rhabdomyosarcoma, or teratoma) and of the same class (eg, testicular germ cell tumors) and differences in relation to normal tissues. The presence of endogenous lectins in tumors, their relation to lectins of normal tissues, and their interaction with glycoconjugates of tumors and normal tissues may contribute to an understanding of intercellular interactions during the complex process of metastatic spread, and may allow to establish a new tool for diagnosis and a lectin-based therapy.