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In mammalian cells, regulation of the expression of proteins involved in iron metabolism is achieved through interactions of iron-sensing proteins known as iron regulatory proteins (IRPs), with transcripts that contain RNA stem-loop structures referred to as iron responsive elements (IREs). Two distinct but highly homologous proteins, IRP1 and IRP2, bind IREs with high affinity when cells are depleted of iron, inhibiting translation of some transcripts, such as ferritin, or turnover of others, such as the transferrin receptor (TFRC). IRPs sense cytosolic iron levels and modify expression of proteins involved in iron uptake, export and sequestration according to the needs of individual cells. Here we generate mice with a targeted disruption of the gene encoding Irp2 (Ireb2). These mutant mice misregulate iron metabolism in the intestinal mucosa and the central nervous system. In adulthood, Ireb2(-/-) mice develop a movement disorder characterized by ataxia, bradykinesia and tremor. Significant accumulations of iron in white matter tracts and nuclei throughout the brain precede the onset of neurodegeneration and movement disorder symptoms by many months. Ferric iron accumulates in the cytosol of neurons and oligodendrocytes in distinctive regions of the brain. Abnormal accumulations of ferritin colocalize with iron accumulations in populations of neurons that degenerate, and iron-laden oligodendrocytes accumulate ubiquitin-positive inclusions. Thus, misregulation of iron metabolism leads to neurodegenerative disease in Ireb2(-/-) mice and may contribute to the pathogenesis of comparable human neurodegenerative diseases.

Seizures evoked by electroshock induce rapid changes in the expression of several genes in the adult brain, including those encoding for neurotrophic factors. Some of the neurotrophic factors induced by brief seizures such as basic fibroblast growth factor and nerve growth factor have been shown to have neuroprotective action. We reasoned therefore that these seizures may protect against neural injury. To test this hypothesis, we examined the effect of electroshock-induced seizures on the vulnerability to cell death in the hippocampus. Cell death was induced by adrenalectomy, which results in a highly selective apoptotic neuronal death in the dentate granule cell layer of the hippocampus. Daily electroshock seizures were administered for seven days to sham-operated and adrenalectomized rats. Neuronal degeneration was evaluated by the highly sensitive and reliable cupric-silver impregnation method. Animals experiencing electroshock seizures were completely protected against adrenalectomy-induced cell death, whereas adrenalectomized animals not exposed to electroshock seizures exhibited substantial neuronal cell degeneration in the dentate granule cell layer. Daily restraint stress did not prevent the adrenalectomy-induced neuronal death, indicating that the neuroprotective effect of the seizure treatment is not accounted for by stress. We conclude that brief controlled seizure-evoked neural activation may allow the sparing of otherwise vulnerable neuronal populations in the injured adult brain. This prompts a need to explore the possibility that controlled administration of electroshock seizures may have therapeutic potential in treating neurodegenerative disorders.

Methods have been developed for the preparation of radioiodinated N-substituted 2 beta-carbomethoxy-3 beta-(4-chlorophenyl)tropanes. The syntheses, physical properties, radiolabeling, and characterization of the pharmacological properties of N-(3(Z)-iodopropen-1-yl)-2 beta-carbomethoxy-3 beta-(4-chlorophenyl)tropane (12) and N-(3(E)-iodopropen-1-yl)-2 beta-carbomethoxy-3 beta-(4-chlorophenyl)tropane (13) are described. 2 beta-Carbomethoxy-3 beta-(p-substituted-phenyl)tropanes are potent ligands for the dopamine transporter. The radioiodinated derivatives are of interest because of the high uptake and prolonged striatal retention that may result from specific binding to low-capacity, high-affinity, dopamine reuptake sites. Radioiodine was introduced into the 3Z and 3E-position of N-(3-iodopropen-1-yl)-2 beta-carbomethoxy-3 beta-(4-chlorophenyl)tropane by iododemetalation of the corresponding 3-(tri-n-butylstannyl) derivatives. Competition binding data of various dopamine reuptake ligands with rat striatal tissue preparation for either [125I]-12 or [125I]-13 exhibited the following order of potency: E-13 > Z-12 > GBR 12909 >> mazindol >>> (-)-cocaine. Tissue distribution studies in rats showed that the E-13 was the best analogue. E-13 showed high striatal uptake (60 min, 1.23% dose/g; 120 min, 0.61% dose/g) and high striatal to cerebellum ratios (60 min, 15.9/1; 120 min, 16.5/1). These studies indicate that iodine-123-labeled E-13 is a potentially useful agent for imaging the dopamine reuptake sites by single-photon-emission computerized tomography.

True extrarenal Wilms' tumor is a rare malignant neoplasm most frequently presenting in the retroperitoneal or inguinal regions. We report an unusual subcutaneous lumbosacral (LS) region extrarenal Wilms' tumor without associated teratomatous tumor elements or associated neural tube defect in a 2 1/2-year-old girl. Pathologic review revealed features of true extrarenal Wilms' tumor, and the patient remains in complete remission following surgery and combination chemotherapy. This report illustrates the importance of early surgical intervention and pathologic examination of similar soft tissue masses in children.

Simultaneous demonstration of acetylcholinesterase (AChE) and horseradish peroxidase (HRP) has been achieved by staining frozen sections with a modified Koelle-Friedenwald thiocholine method for AChE followed directly by the Graham-Karnovsky procedure for HRP. By using sodium sulfite instead of sodium sulfide in the AChE procedure, the final reaction product appears as black AChE granules that contrast sharply with the yellowish-brown HRP granules.

Ten adult male Sprague-Dawley rats were infused with hemicholinium (HC-3) using mini-osmotic pumps over a 14 day period through bilateral, chronically implanted cannulae in the nucleus basalis magnocellularis (nbm). Ten matched controls were infused in the same fashion with saline. HC-3 rats receiving implants demonstrated a significant deficit in maze-learning ability compared with individual and group performances before receiving the implants. In saline rats there was no significant difference in maze-learning ability before and after receiving implants. The HC-3 group receiving implants demonstrated a significant deficit in maze-learning ability compared with the saline control group. Serial sections through nbm from control and HC-3 rats indicated that all cannulae were located within infusion range of nbm. In HC-3 subjects, cholinergic cell bodies were destroyed with concurrent degeneration of terminal fields in cortex. Except for cannula insertion damage, the cholinergic neurotransmitter system appeared unharmed in controls. Stains for neuritic plaques and neurofibrillary damage were negative in both groups. The memory deficit in experimental subjects supported by the demonstrated destruction of nbm cholinergic neurons suggests that HC-3 may be useful in the development of an animal model for Alzheimer's Disease.