Residual dizziness after successful treatment of idiopathic benign paroxysmal positional vertigo originates from persistent utricular dysfunction.

OBJECTIVE: We used ocular vestibular evoked myogenic potentials to investigate the relationship between residual dizziness and utricular function following the canalith repositioning procedure for benign paroxysmal positional vertigo. METHODS: Ocular vestibular evoked myogenic potentials were measured in 44 patients (40 included in analyses, four excluded) with successful results from the canalith repositioning procedure. The patients were examined before treatment and again one week after treatment. We analyzed how various general factors and ocular vestibular evoked myogenic potentials related to residual dizziness. RESULTS: Residual dizziness was not related to gender, affected side, age, duration of symptoms, recurrence, or the results of the initial ocular vestibular evoked myogenic potential test (p > .05). However, residual dizziness was significantly associated with the results of the second ocular vestibular evoked myogenic potential test (p = .007). CONCLUSIONS: Residual dizziness after a successful canalith repositioning procedure may be caused by persistent utricular dysfunction.

Lewis acid-catalyzed propargylic etherification and sulfanylation from alcohols in MeNO2-H2O.

Direct scandium- and lanthanum-catalyzed etherifications of propargyl alcohols 1 and 6 in MeNO2-H2O provided propargyl ethers 3, 4 and 7 in high yields. In addition, reactions of 1 and 6 with thiols exclusively yielded the corresponding propargyl sulfides.

New cyclization of 4-oxahepta-1,6-diynes bearing sulfur and selenium functional groups.

New cyclizations of 1-sulfanyl- and -selanyl-4-oxa-1,6-heptadiynes using sodium alkoxide or thiolates provided 4-alkoxymethyl-3-phenylsulfanyl- and 3,4-bis(sulfanylmethyl)furans in high yields.

Involvement of Ca2+ channel synprint site in synaptic vesicle endocytosis.

The synaptic protein interaction (synprint) site of the voltage-gated Ca(2+) channel (VGCC) alpha1 subunit can interact with proteins involved in exocytosis, and it is therefore thought to be essential for exocytosis of synaptic vesicles. Here we report that the synprint site can also directly bind the mu subunit of AP-2, an adaptor protein for clathrin-mediated endocytosis, in competition with the synaptotagmin 1 (Syt 1) C2B domain. In brain lysates, the AP-2-synprint interaction occurred over a wide range of Ca(2+) concentrations but was inhibited at high Ca(2+) concentrations, in which Syt 1 interacted with synprint site. At the calyx of Held synapse in rat brainstem slices, direct presynaptic loading of the synprint fragment peptide blocked endocytic, but not exocytic, membrane capacitance changes. We propose that the VGCC synprint site is involved in synaptic vesicle endocytosis, rather than exocytosis, in the nerve terminal, via Ca(2+)-dependent interactions with AP-2 and Syt.

Tubulin and CRMP-2 complex is transported via Kinesin-1.

The transport of tubulin and microtubules in a growing axon is essential for axonal growth and maintenance. However, the molecular mechanism underlying the linkage of tubulin and microtubules to motor proteins is not yet clear. Collapsin response mediator protein-2 (CRMP-2) is enriched at the distal part of growing axons in primary hippocampal neurons and plays a critical role in axon differentiation through its interaction with tubulin dimer and Numb. In this study, we show that CRMP-2 regulates tubulin transport by linking tubulin and Kinesin-1. The C-terminal region of CRMP-2 directly binds to the tetratricopeptide repeat domain of kinesin light chain 1 (KLC1). Soluble tubulin binds to the middle of CRMP-2 and forms a trimeric complex with CRMP-2/KLC1. Furthermore, the movement of GFP-tubulin in the photobleached area is weakened by knockdown of KLCs or CRMP-2. These results indicate that the CRMP-2/Kinesin-1 complex regulates soluble tubulin transport to the distal part of the growing axon.

CRMP-2 binds to tubulin heterodimers to promote microtubule assembly.

Regulated increase in the formation of microtubule arrays is thought to be important for axonal growth. Collapsin response mediator protein-2 (CRMP-2) is a mammalian homologue of UNC-33, mutations in which result in abnormal axon termination. We recently demonstrated that CRMP-2 is critical for axonal differentiation. Here, we identify two activities of CRMP-2: tubulin-heterodimer binding and the promotion of microtubule assembly. CRMP-2 bound tubulin dimers with higher affinity than it bound microtubules. Association of CRMP-2 with microtubules was enhanced by tubulin polymerization in the presence of CRMP-2. The binding property of CRMP-2 with tubulin was apparently distinct from that of Tau, which preferentially bound microtubules. In neurons, overexpression of CRMP-2 promoted axonal growth and branching. A mutant of CRMP-2, lacking the region responsible for microtubule assembly, inhibited axonal growth and branching in a dominant-negative manner. Taken together, our results suggest that CRMP-2 regulates axonal growth and branching as a partner of the tubulin heterodimer, in a different fashion from traditional MAPs.