HEOCHROMOCYTOMA AND PARAganglioma are tumors of the autonomic nervous system. Terminology in science and clinical practice is divergent. Herein, we use the term pheochromocytoma for location in the adrenal glands, extraadrenal abdominal, and thoracic locations (eg, where nearly all tumors are endocrinologically active). In contrast, the term paraganglioma is only used for tumors in the head and neck area where most tumors are nonfunctioning. All these tumors have been described as sporadic and as hereditary entities. [1][2][3] Estimated yearly incidence of

The molecular organization of presynaptic active zones during calcium influx-triggered neurotransmitter release is the focus of intense investigation. The Drosophila coiled-coil domain protein Bruchpilot (BRP) was observed in donut-shaped structures centered at active zones of neuromuscular synapses by using subdiffraction resolution STED (stimulated emission depletion) fluorescence microscopy. At brp mutant active zones, electron-dense projections (T-bars) were entirely lost, Ca2+ channels were reduced in density, evoked vesicle release was depressed, and short-term plasticity was altered. BRP-like proteins seem to establish proximity between Ca2+ channels and vesicles to allow efficient transmitter release and patterned synaptic plasticity.

ARAGANGLIOMA SYNDROME(PGL) is a clinical term that has been introduced to describe a group of diseases in which patients may have neoplasias of several paraganglia. 1,2 For at least 4 decades, it has been known that such conditions may be heritable. 3 In addition, thoracic, retroperitoneal, and adrenal lo-cations (eg, extra-adrenal or adrenal pheochromocytomas) are also wellrecognized components of PGL. 4,5 Thus, Author Affiliations and a complete list of the members of the European-American Paraganglioma Study Group appear at the end of this article.

To probe exocytosis at a cortical glutamatergic synapse, we made capacitance measurements in whole-cell recorded hippocampal mossy fiber terminals. Evaluation of different methods by using a morphology-based equivalent electrical model revealed that quantitative capacitance measurements are possible in this presynaptic structure. Voltage pulses leading to presynaptic Ca 2؉ inflow evoked large capacitance signals that showed saturation with increasing pulse duration. The mean peak capacitance increase was 100 fF, corresponding to a pool of Ϸ1,400 releasable vesicles. Thus hippocampal mossy fiber synapses have a vesicular ''maxipool.'' Large pool size and rapid vesicle recycling may underlie the uniquely large extent of activity-dependent plasticity in this synapse.

Whether glutamate is released rapidly, in an all-or-none manner, or more slowly, in a regulated manner, is a matter of debate. We analyzed the time course of excitatory postsynaptic currents (EPSCs) at glutamatergic neuromuscular junctions of Drosophila and found that the decay phase of EPSCs was protracted to a variable extent. The protraction was more pronounced in evoked and spontaneous quantal EPSCs than in action potential-evoked multiquantal EPSCs; reduced in quantal EPSCs from endophilin null mutants, which maintain release via kiss-and-run; and dependent on synaptotagmin isoform, calcium, and protein phosphorylation. Our data indicate that glutamate is released from individual synaptic vesicles for milliseconds through a fusion pore. Quantal glutamate discharge time course depends on presynaptic calcium inflow and the molecular composition of the release machinery.

The germline NF1 mutational spectra comprise intragenic mutations and deletions in individuals with pheochromocytoma and NF1. NF1 mutations tended to cluster in the CSR over the RAS-GAP domain, suggesting that CSR plays a more prominent role in individuals with NF1-pheochromocytoma than in NF1 individuals without this tumor. Loss-of-heterozygosity of NF1 markers in NF1-related pheochromocytoma was significantly more frequent than in sporadic pheochromocytoma, providing further molecular evidence that pheochromocytoma is a true component of NF1.

The succinate dehydrogenase (SDH) is a mitochondrial enzyme complex with an important role in oxydative phosphorylation and intracellular oxygene sensing and signaling. Mutations in the SDHB (1p35-36) and SDHD subunits (11q23) give rise to the paraganglioma syndromes (PGL), namely PGL 4 and PGL 1, and generate paraganglioma and pheochromocytoma. For both genes mutations have been described that result in a loss of function of the gene products. SDHBmutations were found in five of eight exons and in two introns, SDHD mutations in all four exons and one intron. Phenotypes and rate of malignancy of SDHB and SDHD seem to be different, with a higher frequency of head-and-neck tumors in SDHD and indications of a higher risk of malignancy in SDHB mutations. As routine diagnostic procedure all SDH mutation carriers should have urine catecholamine analysis as well as pelvic, abdominal, thoracic and skull/neck MRI.

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