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B Kirschenbaum

Publications and source records attributed to B Kirschenbaum.

4 recordsLinked to original sources
PubMed1990

Posthoc phosphorylation of proteins derived from ischemic rat hippocampus, striatum and neocortex.

Disruption of the brain's protein phosphorylation system by ischemia may cause irreversible metabolic and structural alterations leading eventually to cell death. To examine the effect of ischemia on the phosphorylation state of brain proteins, tissue homogenates derived from the hippocampus, striatum and neocortex of normal rats and rats subjected to severe forebrain ischemia were phosphorylated with [gamma-32P]ATP. The phosphorylated proteins were separated by two-dimensional polyacrylamide gel electrophoresis and changes were assessed by autoradiography. Cerebral ischemia caused marked alterations of the phosphorylation state of many brain proteins; phosphorylation of some proteins was increased while phosphorylation of others was decreased. Despite differences in the sensitivity of the hippocampus, striatum and neocortex to ischemic injury the direction and approximate magnitude of protein phosphorylation changes caused by ischemia were similar in all three regions. Since the pattern of protein phosphorylation in the ischemia-vulnerable hippocampus was identical to that in the ischemia-resistant paramedian neocortex we conclude that abnormalities of protein phosphorylation may be necessary for ischemic injury to neurons but none are sufficient to explain the selective vulnerability of certain brain regions to ischemic damage.

Animals↗
PubMed1987

Nerve growth factor increases the number of functional Na channels and induces TTX-resistant Na channels in PC12 pheochromocytoma cells.

The PC12 clone is a line of rat pheochromocytoma cells that undergoes neuronal differentiation in the presence of NGF protein. In the absence of NGF, PC12 cells are electrically inexcitable, while after several weeks of NGF treatment they develope Na+ action potentials. Past estimates made by measuring binding of 3H-saxitoxin (STX) indicate that NGF treatment brings about a large increase in Na channel density that is of sufficient magnitude to account for the induction of excitability. We have now used 22Na uptake to measure the Na permeability of PC12 cells before and after long-term NGF treatment. Treatment with NGF does not change the resting Na+ permeability. The alkaloid toxins veratridine and batrachotoxin (BTX) and scorpion toxin were used to activate Na channels. Such studies demonstrate that these toxins induce TTX-sensitive Na uptake in both NGF-treated and untreated cells and reveal differences in functional Na channel numbers per cell and per unit of membrane area that are similar to those found in the STX binding studies. On the other hand, affinities for drugs that activate these channels are not affected by NGF treatment. We also find that NGF-treated PC12 cells contain a population of Na channels with low affinity for TTX. These channels account for 5-20% of total BTX or veratridine-stimulated flux. Thus, NGF has 2 effects regarding the Na channels of PC12 cells: it increases the number of functional Na channels that otherwise behave similarly to those present before NGF treatment, and it induces the presence of TTX-resistant Na channels. These findings indicate that the PC12 model system may serve to study the developmental regulation of Na channel expression and properties.

Animals↗
PubMed1978

Phenylketonuria and scleroderma.

Two mentally retarded siblings, one with severe segmental scleroderma and the other with atrophoderma of Pasini and Pierini, were found at the ages of 6 and 10 years to have phenylketonuria (PKU). The belief that a common pathomechanism exists between morphea and atrophoderma of Pasini and Pierini is supported by the case of the two siblings. Disorders in tryptophan metabolism can occur in both PKU and scleroderma. For a low phenylalanine diet to be effective in PKU, it has to be instituted at an early age. Phenylketonuria should be considered in infants and children with sclerodermatous skin lesions.

Child↗