Within the last few years several papers on the formation of colloidal manganese dioxide have appeared. Thus far, however, the intermediate formation of colloidal manganese dioxide in the ordinary oxidations of organic compounds with potassium permanganate has not been reported. The following paper is a report of some observations on this subject. In the course of the experiments it was found that the gelatinous form of colloidal manganese dioxide first obtained is slowly and automatically converted into a limpid colloidal solution. This transformation was studied somewhat more in detail and was found to be readily influenced (I) by the temperature a t which the gel form was prepared, (2) by the concentration of the reacting solutions, (3) by the temperature to which the gel was subjected during the transformation, and (4) by the varia-4 Dissertation, Heidelberg (1907). G. Bredig and A. Marck, "Ueber kolloides MnOz sol und sein Verhalten gegen # 2 0 2 ; "
Experiments were performed to assess the diagnostic value of radiography in osteo-arthritis (OA) of the knee joint in C57Bl mice. Comparative histological and radiographic examination of knee joints from 96 animals showed that if the classical diagnostic criteria (narrowing of the joint space, sclerosis of the subchondral bone, deformation of the joint epiphyses) are applied, OA is not readily detectable by radiography. If these criteria are extended to include radiographic changes in the menisci (enlargement, deformation, increased and/or heterogeneous density), the frequency of detection is much improved. However, except in the severest forms of OA, radiography does not afford a satisfactory means of distinguishing between various degrees of severity. The qualitatively evaluated data nevertheless do suggest that quantitative radiographic diagnosis of OA of the murine knee joint may be useful, both for improving the detection rate and for discriminating various degrees of OA.
Comparative histopathological and radiographic investigations in the C57BL mouse model of spontaneous osteo-arthritis of the knee-joint indicate that there is a relation between quantitative radiographic diagnosis and semiquantitative histopathological diagnosis. Statistical analysis based on a set of quantitative radiographic parameters of the mouse knee-joint shows that the greater part of the radiographic information reflecting the histopathological degree of the osteo-arthritis is contained in the projection areas of the lateral and medial meniscus: progression of the osteo-arthritic process is accompanied with enlargement of the menisci. On the basis of these observations, a radiography score for the osteo-arthritis has been constructed, which consists of a weighted sum of the - suitably transformed - projection areas of the lateral and medial meniscus. In addition to the size of the menisci, the width of the joint space is also a useful quantitative parameter of osteo-arthritis of the mouse knee-joint.
In 1937 Krebs and Johnson1 proposed that acetopyruvic acid is an intermediate in the biochemical synthesis of acetoacetic acid from acetic and pyruvic acids. This compound has been previously described by Mumm and Bergell,2 who also prepared several derivatives. However, the results reported by these workers seemed to indicate that this compound spontaneously undergoes unknown reactions in aqueous solution.Since knowledge of such reactions would be of great importance in a critical evaluation of its possible biochemical role, further study of its preparation and properties seemed required. In routine practice it was also found that the synthesis, as described by Mumm and Bergell, gave irregular results and that the procedure could be improved materially.In this report some details concerning the synthesis, two unreported derivatives, stability, acid behavior, and some data on the oxidation mechanisms of acetopyruvic acid are described.I. Synthesis and Properties.-Difficulties encountered with the Mumm and Bergell procedure for this synthesis led to the trial of sodium methylate in the synthesis of the sodio-ester compound. Freri3 has shown that the methyl ester is formed in this condensation when sodium methylate is used as condensing agent, and the methyl ester was thought to have the advantage of being more rapidly hydrolyzed than the ethyl ester. However, it was soon realized that the difficulties in the preparation of the free acid from the sodio-ester arose from the fact that the sodium salt of the acid produced was almost as rapidly hydrolyzed as was the ester itself under the conditions of the Mtunm and Bergell synthesis. The reactions involved are schematized in reactions (1) and (2).CH8COCH==C(ONa)COOC2H6 + NaOH -> CHsCOCH=C(ONa)COONa + C2H6OH (1) CH3COCH-C (ON a) COONa + NaOH ->-CHsCOCHs + (COONah (2)In the Mumm and Bergell synthesis reaction * Supported in part by the Wisconsin Alumni Research Foundation.
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