ATP regulation of ciliary beat frequency in rat tracheal and distal airway epithelium

Ciliary beat frequency (CBF) was measured by video-optical microscopy in rat tracheal and distal airway ciliary cells using a slice preparation. In tracheal ciliary cells (tracheal slice), ATP or 2-methylthio ATP (MeSATP) increased CBF, which was inhibited by suramin (100 microm, an inhibitor of purinergic receptor). Ionomycin (5 microm) or thapsigargin (2 microm) increased CBF similarly. Ca2+-free solution or addition of Ni2+ (1 mm) decreased CBF gradually by approximately 25% and subsequent stimulation with ATP (10 microm) increased CBF transiently. The purinergic agonist experiments demonstrated that ATP increases CBF in tracheal ciliary cells via both P2X and P2Y receptors. ATP increased the intracellular calcium concentration ([Ca2+]i) in tracheal ciliary cells. However, in distal airway ciliary cells (lung slice), ATP did not increase CBF and [Ca2+]i, although a Ca2+-free solution decreased CBF, and ionomycin (5 microm) or thapsigargin (2 microm) increased it. Moreover, acetylcholine (100 microm) did not increase CBF in distal airway ciliary cells, although it increased CBF in tracheal ciliary cells. Terbutaline (10 microm), a selective beta2-adrenergic agonist, increased CBF in both tracheal and distal airway ciliary cells. These observations suggest that the Ca2+-mobilization mechanisms via purinergic or muscarinic receptors of the distal airway ciliary cell may be different from those of the tracheal ciliary cell. In conclusion, the CBF increase is differently regulated in the tracheal and distal airway epithelia of the rat.     

Stereological analysis of Reinke's crystals in human Leydig cells

Summary Reinke's crystals in human Leydig cells were analyzed stereologically to assess their functional role. Testicular tissues were taken from seven older men (57–82 years old) with prostatic carcinoma and also from seven younger men (26–38 y.o.) complaining of male infertility. Sections 0.5 m thick, stained with toluidine blue or Heidenhein's iron-hematoxylin were examined by a point-counting method and with a Particle Measurement Computor System (MC). When the patients were grouped by age, the mean crystal volume, the number of crystals per cell, the volume of crystals per cell and the volume ratio of crystals to cell were significantly larger in the older age group than in the younger age group. In particular, the latter three variables correlated well with the age of subjects, with correlation coefficients of r=0.66–0.85. On the other hand, none of these variables had any correlation with the concentration of plasma testosterone. These results indicate that Reinke's crystals can be considered as degenerative products in cell life but not as facultative constituents for testosterone production.Supported in part by a grant from Medical Foundation of Ehime, Japan     

Electrical activity in the prefrontal cortex specific to no-go reaction of conditioned hand movement with colour discrimination in the monkey

Summary Monkeys were trained to perform hand movements in a reaction time task with discrimination between positive (go) and negative (no-go) light signals, and field potentials in various cortical areas were recorded and analysed with chronically implanted cortical electrodes. As previously reported, areas such as the prefrontal, premotor and motor cortices were active in association with simple visually-initiated, reaction-time hand movements. The caudal part of the dorsal bank of the principal sulcus was found to be activated specifically on no-go trials during discrimination, and revealed a relatively sharp surface-negative, depth-positive potential. The potential appeared at a latency of 110–150 ms, which was 150–210 ms earlier than the movement onset on go trials. With reversal of the go and no-go signals, this potential was found to be recorded only on no-go trials, irrespective of the colour used for the stimulus. It is suggested that the activity in the dorsal bank of the principal sulcus is related to the judgement not to execute the movement and/or the suppression of motor execution.     

Studies on cortical field potentials recorded during learning processes of visually initiated hand movements in monkeys

Summary A monkey was trained to lift a lever by wrist extension in response to a light stimulus. During the learning process of the task over several months, field potentials related not only to the task performance but also to substitution and stimulation experiments were recorded with chronically implanted electrodes on the surface and at a depth of 2.5–3.0 mm in the prefrontal, premotor, motor and prestriate cortices. In the substitution experiment, an examiner lifted a lever for the monkey so that it was watching the light and rewarded without the hand movement. In the stimulation experiment, the same light stimulus was simply delivered to the monkey. In a naive monkey which lifted the lever independently of the stimulus, stimulus-locked potentials were evoked by the task experiment in those cortices except the motor cortex, but none was elicited by the substitution or stimulation experiment. In a welltrained monkey, the substitution and stimulation experiments induced almost the same potentials as those prior to the task movement in respective cortices except the motor cortex, in which the component of cerebellar-induced premovement potential was not observed during the substitution and stimulation experiments. At an intermediate stage of learning, the situation was intermediate between the naive and well-trained stages and most premovement potentials except those in the motor cortex were elicited by the substitution experiment in reduced sizes, but nothing by the stimulation experiment.The present study suggests that the neuronal circuits for the operantly conditioned movement are functionally organized and gradually consolidated in the learning process, and that the consolidation is made earlier for the circuit involving association and premotor cortices than the circuit including the motor cortex in the process. The circuit to the motor cortex via the cerebro-cerebellar interconnection is recruited only on the execution of movement.     

ASK1 is essential for endoplasmic reticulum stress-induced neuronal cell death triggered by expanded polyglutamine repeats

Expansion of CAG trinucleotide repeats that encode polyglutamine is the underlying cause of at least nine inherited human neurodegenerative disorders, including Huntington's disease and spinocerebellar ataxias. PolyQ fragments accumulate as aggregates in the cytoplasm and/or in the nucleus, and induce neuronal cell death. However, the molecular mechanism of polyQ-induced cell death is controversial. Here, we show the following: (1) polyQ with pathogenic repeat length triggers ER stress through proteasomal dysfunction; (2) ER stress activates ASK 1 through formation of an IRE1-TRAF2-ASK1 complex; and (3) ASK1(-/-) primary neurons are defective in polyQ-, proteasome inhibitor-, and ER stress-induced JNK activation and cell death. These findings suggest that ASK1 is a key element in ER stress-induced cell death that plays an important role in the neuropathological alterations in polyQ diseases.     

Phosphorylation of cofilin by LIM-kinase is necessary for semaphorin 3A-induced growth cone collapse

Semaphorin 3A is a chemorepulsive axonal guidance molecule that depolymerizes the actin cytoskeleton and collapses growth cones of dorsal root ganglia neurons. Here we investigate the role of LIM-kinase 1, which phosphorylates an actin-depolymerizing protein, cofilin, in semaphorin 3A-induced growth cone collapse. Semaphorin 3A induced phosphorylation and dephosphorylation of cofilin at growth cones sequentially. A synthetic cell-permeable peptide containing a cofilin phosphorylation site inhibited LIM-kinase in vitro and in vivo, and essentially suppressed semaphorin 3A-induced growth cone collapse. A dominant-negative LIM kinase, which could not be activated by PAK or ROCK, suppressed the collapsing activity of semaphorin 3A. Phosphorylation of cofilin by LIM-kinase may be a critical signaling event in growth cone collapse by semaphorin 3A.     

Why is the diverse U letter relationship between embarrassment and psychological distance observed? In view of Schlenker and Leary (1982)'s self-presentation model of social anxiety

The aim of the present study is to explain why there is "the diverse U letter relationship" between embarrassment and psychological distance empirically, in view of Schlenker and Leary (1982)'s self-presentation model of social anxiety. In Study 1, those relationships were observed in three different situations. In Study 2, the main effect of motivation for avoiding rejection and the damage of self-image, and their interaction with embarrassment was examined by hierarchical regression analysis. In the first step, the psychological distance, in the second step, the main effect of both, and in the third step, the interaction was entered. As a result, in the second step, both main effects were significant, but in the third step, only interaction was significant, and both main effects were not significant. This showed that the interaction could predict embarrassment, although the psychological distance was controlled. Finally, this result was discussed in view of social norm.     

Seeligeriolysin O, a protein toxin of Listeria seeligeri, stimulates macrophage cytokine production via Toll-like receptors in a profile different from that induced by other bacterial ligands

Seeligeriolysin O (LSO), a member of cholesterol-dependent cytolysins of Listeria seeligeri, exhibits cytokine-inducing activity. In this study, we examined the profile of cytokines expressed in macrophages of mice after stimulation with full-length form of recombinant LSO (rLSO530), C-terminal-truncated protein (rLSO483) and two authentic cytokine-inducing Toll-like receptor (TLR) ligands from bacteria, peptidoglycan (PGN) and LPS. Both rLSO530 and rLSO483 were able to induce IL-12 p40 and IL-12 p70 more strongly in macrophages than PGN or LPS. In contrast, IFN-beta and nitric oxide were induced by LPS but not by rLSO530, rLSO483 or PGN. In the presence of exogenously added IFN-beta, IL-12 p40 and IL-12 p70 production was inhibited after LSO stimulation, but IL-12 p70 production was enhanced after PGN stimulation. Although LSO signaling appeared to be associated with both TLR2 and TLR4, the profile of cytokine production by LSO stimulation was distinct from those by stimulation with PGN or LPS. Thus, it was shown that LSO is a unique bacterial ligand that induces macrophage cytokine production in a manner different from PGN or LPS.