M. Morphological obser6ation of laryngeal motoneurons by means of cholera toxin B subunit tracing technique. Acta Otolaryngol (Stockh) 1998; Suppl 539: 98-105.Gross anatomical and histological studies and immunohistochemical demonstration of cholera toxin B subunit used as a retrograde tracer were performed to investigate distinct muscle fibre bundles (MFBs) in the feline intrinsic laryngeal muscles (ILMs) and to characterize the respective supplying motoneurons in the nucleus ambiguus (AM). Distinct bundles were observed in all ILMs except the lateral cricoarytenoid muscle. Motoneurons supplying MFBs related to phonation located more medially than others. Motoneuron size did not differ between distinct MFBs in the same muscle. Neurodendrites for the cricothyroid muscle (CT) and adductor motoneurons extended dorsomedially, ventrolaterally and ventromedially, while those for the posterior cricoarytenoid muscle (PCA) motoneurons stretched dorsomedially and ventrolaterally. We conclude that distinct MFBs in ILMs play different roles in laryngeal functions, and that corresponding motoneurons have their own specific visceroneural nature allowing regulation of complex laryngeal functions. To receive information from the central nervous system, laryngeal motoneuron dendrites extended to regions locating respiratory, phonatory and swallowing neurons.

Using parvalbumin immunohistochemistry to determine the distribution of muscle fiber types in the feline thyroarytenoid muscle (TA), we clearly distinguished the vocalis (with predominance of "slow" type 1 fibers) from the external TA (in which "fast" type 2 fibers predominated, especially in its rostral part). Reconstruction of serial frontal sections of the TA allowed the stereoscopic study of each division. The existence of a rudimentary laryngeal ventricle separating the true and false vocal folds in cats was demonstrated anatomically and histologically, and its relationships to each division of the TA were established. Our results suggest that the vocalis, fitted for enduring activities, is suited for voice control. The fast, rostral part of the external TA seems suited to laryngeal sphincteric demands, while its caudal counterpart may act in both functions. The anatomic individualization of the divisions of the TA may suggest that they play distinct physiological roles and may imply that they should not be considered a single functional unit.

Bongkrekic acid (BKA), isolated from the bacterium Burkholderia cocovenenans, is an inhibitor of adenine nucleotide translocator, which inhibits apoptosis, and is thus an important tool for the mechanistic investigation of apoptosis. An efficient total synthesis of BKA has been achieved by employing a three-component convergent strategy based on Kocienski-Julia olefination and Suzuki-Miyaura coupling. It is noteworthy that segment B has been prepared as a new doubly functionalized coupling partner, which contributes to shortening of the number of steps. Torquoselective olefination with an ynolate has also been applied for the efficient construction of an unsaturated ester. Furthermore, it is revealed that 1-methyl-2-azaadamantane N-oxyl is an excellent reagent for final oxidation to afford BKA in high yield. Based on the total synthesis, several BKA analogues were prepared for structure-activity relationship studies, which indicated that the carboxylic acid moieties were essential for the apoptosis inhibitory activity of BKA. More easily available BKA analogues with potent apoptosis inhibitory activity were also developed.

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