A quinol peroxidase inhibitor prevents secretion of a leukotoxin from Aggregatibacter actinomycetemcomitans.

BACKGROUND AND OBJECTIVE: Quinol peroxidase (QPO) catalyzes peroxidase activity using quinol in the respiratory chain as a substrate. Quinol peroxidase is essential for the secretion of leukotoxin (LtxA), which destroys leukocytes and erythrocytes in humans and is one of the major virulence factors of Aggregatibacter actinomycetemcomitans, which is associated with localized aggressive periodontitis. In the present study, we aimed to find a highly potent QPO inhibitor to attenuate the virulence of A. actinomycetemcomitans. MATERIAL AND METHODS: For screening of QPO inhibitors, QPO activity was measured kinetically by SpectraMax Plus with 96-well UV plates. Three hundred compounds in the Kitasato Institute for Life Sciences Chemical Library were screened. Secretion of LtxA in the culture supernatant was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cytotoxicity against human promyelocytic leukemia cell line (HL-60) cells from the culture supernatant was measured by Trypan Blue exclusion test. RESULTS: The present study characterized ascofuranone as a highly potent inhibitor of QPO (K(i) = 9.557 +/- 0.865 nm). Ascofuranone inhibited secretion of LtxA by A. actinomycetemcomitans in a dose-dependent manner, making A. actinomycetemcomitans less pathogenic to HL-60 cells. CONCLUSION: Quinol peroxidase inhibitors are promising candidates as alternative drugs for the treatment and prevention of the onset of localized aggressive periodontitis. Using ascofuranone as a seed compound, further study of QPO inhibitors could provide novel chemotherapeutic strategies for controlling localized aggressive periodontitis.

Confocal laser scanning and electron-microscopic analyses of the relationship between VIP-like and GnRH-like-immunoreactive neurons in the lateral septal-preoptic area of the pigeon.

The lateral septum and the preoptic area of birds comprise neurons immunoreactive (ir) for vasoactive intestinal polypeptide (VIP) and gonadotropin-releasing hormone (GnRH). By use of immunohistochemical single- and double-labeling techniques, we have investigated the distribution and the connections of these two types of peptidergic neurons in the lateral septal-preoptic area of the pigeon at both the light- and electron-microscopic levels. An accumulation of VIP-like-ir neurons, some of which are cerebrospinal fluid-contacting neurons, is found in the area adjacent to the ventromedial walls of the lateral ventricles in the lateral septum corresponding to the medial part of the lateral septal organ. VIP-like-ir terminals are scattered throughout the lateral septal-preoptic area, which also contains GnRH-like-ir cell bodies. The number of GnRH-like-ir cell bodies in the lateral septum is smaller than that of the VIP-like-ir neurons. GnRH-like-ir cells have a simple bipolar or multipolar shape and a beaded axon that emerges from the soma or one of the proximal dendrites. Confocal laser scanning microscopy has shown VIP-like-ir terminals in close apposition to GnRH-like-ir cell bodies in the lateral septal-preoptic area. Furthermore, the electron-microscopic double-immunolabeling has revealed synaptic contacts between VIP-like-ir axon terminals and GnRH-like-ir cell bodies or dendrites. These contacts, however, do not show synaptic specializations. The present results suggest that functional interactions take place between VIP and GnRH neurons in the lateral septal-preoptic area of the pigeon and that these interactions are involved in mediating photoperiodic responses.

Electron-microscopic investigations of vasoactive intestinal peptide (VIP)-like immunoreactive terminal formations in the lateral septum of the pigeon.

Vasoactive intestinal peptide (VIP)-like immunoreactive terminal fields were examined in the lateral septum of the pigeon by means of immunocytochemistry. According to light-microscopic observations, these projections originated from VIP-like immunoreactive cerebrospinal fluid (CSF)-contacting neurons, which are located in the ependymal layer of the lateral septum and form a part of the lateral septal organ. The processes of these cells gave rise to dense terminal-like structures in the lateral septum. Pre-embedding immuno-electron microscopy revealed that VIP-like immunoreactive axon terminals had synaptoid contacts with perikarya of small VIP-immunonegative neurons of the lateral septum, which were characterized by an invaginated nucleus, numerous mitochondria, a well-developed Golgi apparatus, endoplasmic reticulum and a small number of dense-core vesicles (about 100 nm in diameter). VIP-like immunoreactive axons were also seen in contact with immunonegative dendrites in the lateral septum. In both axosomatic and axodendritic connections, VIP-like immunoreactive presynaptic terminals contained large dense-core vesicles, clusters of small vesicles and mitochondria. These findings suggest that VIP-immunoreactive neurons of the lateral septal organ project to small, presumably peptidergic nerve cells of the lateral septum and that the VIP-like neuropeptide serves as a neuromodulator (-transmitter) in this area.

Megaíleo chagásico: descriçäo de um caso / Chagasic megaileum: report of a case

É apresentado um caso de megaíleo de natureza chagásica. O paciente, portador da Doença de Chagas, branco com 41 anos, apresentava história de 3 anos de episódios de cólicas abdominais, distensäo e diarréia, que foram se tornando mais intensas e mais freqüentes. Fora crises, apresentava-se assintomático. O diagnóstico de megaíleo foi estabelecido por meio do estudo radiológico contrastado do intestino delgado. O estudo histológico realizado em fragmento obtido à intervençäo cirúrgica mostrou diminuiçäo do número de células ganglionares dos plexos mientéricos