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Biomedical subjects

S Kramer

Publications and source records attributed to S Kramer.

At least 217 records · Page 12Linked to original sources
PubMed1975

The effect of age on the long-term response of bone marrow to local fractionated irradiation.

The in-field long-term progressive response of bone marrow to localized fractionatedradiation to the thoracic spine was observed in weanling and adult rats. Total dose levels were 1800,3600 and 5400 rads given in daily fractions of 180 rads for 900 rads perweek, to simulate the clinical setting. Animals were sacrificed at 4 1/2, 6, 8, and 10months after irradiation, and bone marrow from within the treated area was ezamined. The juvenile marrow repopulated to higher levels of cellularity and after higher doses of radiation than the adult. The degree of marrow depletion, time of repopulation, and ultimate level of repopulation after cessation of irradiation were all dependent on the total dose. Some of the suggested clinical implications include re-evaluation of the lower doses given to children.

Age Factors↗
PubMed1975

The effect of porphyrin precursors on monosynaptic reflex activity in the isolated hemisected frog spinal cord.

The porphyrin precursors beta-aminolevulinic acid (beta-ALA) and porphobilinogen (PBG) which accumulate, and are excreted in the urine in increased amounts during acute attacks of porphyria, were tested for their effects on reflex activity in the isolated hemisected spinal cords of Xenopus laevis. The two compounds were found to exert an inhibitory effect on monosynaptic ventral root responses, as well as on dorsal root responses (DRR) and dorsal root potentials (DRP). The latent period for inhibition of the monosynaptic response was longer than that for the DRR and DRP. The sensitivity of the preparations to the effect of the porphyrin precursors was subject to some seasonal variation. BETA-ALA and PBG did not effect conduction in isolated sciatic nerves at a concentration of 1 mg/ml.

Aminolevulinic Acid↗