Biomedical subjects
Publications and source records attributed to E Rosenfeld.
The case of a 36-year old man with IgA kappa multiple myeloma in whom meningeal myelomatosis developed is reported, and a brief review of previously published cases is made. Meningeal involvement develops in patients with high tumoral mass myeloma. Because of its poor prognosis, central nervous system chemoprophylaxis based on clinical and cerebrospinal fluid data, and systemic treatment according to severity, is suggested.
Human erythrocytes were exposed in vitro to diagnostic intensities of ultrasound. Various antigenic tests were conducted to see if the different blood group markers had been changed. No change was observed following sonication for Ss, M, K1, ABO, and the rhesus factors. However a marked reduction was found for the N antigen when assayed using the lectin isolated from Vicia graminea. Several experiments were performed to ensure that this effect was not an artefact. If the cells were not resuspended in fresh medium immediately following sonicating then the magnitude of the effect rapidly decreased. We were unable to detect free N antigen in the supernatants from the sonicated cell suspensions. We were also unable to demonstrate changes in the level of the N antigen following sonication if we used anti-N sera from rabbits. A surprising observation was that different batches of the lectin preparation from the same manufacturer could eliminate the effect.
Photodynamic action promoted by Rose Bengal was evaluated in solutions of unsaturated fatty acids or histidine, and on beef heart submitochondrial particles. Rose Bengal-promoted photooxidation of histidine was mainly due to the opening up of the imidazole ring by singlet oxygen. Photosensitization of polyunsaturated fatty acids (PUFA) resulted in oxygen consumption and thiobarbituric acid-reactive substances (TBARS) formation, the extent of which was linearly related to the increasing degree of unsaturation. Photosensitization of submitochondrial particles caused oxygen consumption and TBARS production. These processes involved two different reaction components: during the first, most of the mitochondrial proteins were inactivated, the most sensitive being succinate dehydrogenase and cytochrome c. The values for the rate ratios of [TBARS] formation/[O2] consumption for the first and second phase were 0.36 and 1.32%, respectively, pointing to a larger contribution of lipid peroxidation during the second phase. The calculation of the rate constants for reaction of singlet oxygen with mitochondrial proteins suggests that singlet oxygen is more reactive towards proteins than to PUFA. The biological role of this selectivity is discussed in terms of the mitochondria as one of the first targets for photosensitized reactions.
Rose bengal photosensitized the formation of frank single-strand breaks (SSBs) in double-stranded, supercoiled pBR322 DNA as measured by neutral agarose electrophoresis. The yield of SSBs followed first order kinetics with respect to light fluence and dye concentration. The efficiency of cleavage was more than 20 times greater in an argon atmosphere than in an oxygen atmosphere. The quantum yield in an air atmosphere was 1.7 (+/- 0.3) X 10(-8). Sodium azide quenched the cleavage more efficiently in an oxygen atmosphere than when the oxygen concentration was reduced. Isopropanol and mannitol were poor quenchers; ribose-5-phosphate and guanosine-5'-monophosphate did not quench the cleavage. Substituting D2O for H2O increased the yield of SSBs in both oxygen and oxygen-depleted atmospheres. The results are consistent with initiation of cleavage by reaction of the triplet state of rose bengal (or a radical derived from it) with DNA. In the presence of oxygen, an additional mechanism is introduced.
In experimental endocrinology and for studies of disturbed homeostasis caused by alterations of mineral metabolism rat incisors are known test model. Recently they will be relevant to interpret effects of xenobiotics. In our experiments we found remarkable correlations between specific organ toxicity (affinity) and histotropic effects in the incisors (enamel or dentine), further variations of the reaction in relation to the time of application.
The incisor of the rat is a sensitive biological indicator which records nutritive and hormonal disorders as well as toxic influences. The present investigation was aimed to provide information whether or not the manifestation of cyclophosphamide-caused hypoplasias could be altered by an induction (phenobarbital) or inhibition (carbon tetrachloride) of the liver biotransformation capacity. Cyclophosphamide (15 or 30 mg/kg) was injected intraperitoneally. Pretreatment of the rat with phenobarbital produced an increase (35%) of the malformation, whereas carbon tetrachloride led to a dose dependent decrease (30 or 50%). Our investigations suggest that the cyclophosphamide induced defect of the incisor is due to an alteration of the metabolic liver function.
The effect of ultrasonic waves on the activity of glucoamylase bound to a porous polystyrene matrix is investigated in this Paper. The immobilized enzyme was sonated in a flow cuvette at frequencies between 1 and 11 MHz and sound intensities up to 5 kW m-2. The effect was measured as a function of the type and concentration of the substrate, carrier particle size, flow rate of the substrate solution and ultrasonic frequency. The activity increase is discussed in terms of a possible ultrasonic mechanism.
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