Bioorganic/inorganic hybrid composition of sponge spicules: Matrix of the giant spicules and of the comitalia of the deep sea hexactinellid Monorhaphis

The giant basal spicules of the siliceous sponges Monorhaphis chuni and Monorhaphis intermedia (Hexactinellida) represent the largest biosilica structures on earth (up to 3 m long). Here we describe the construction (lamellar organization) of these spicules and of the comitalia and highlight their organic matrix in order to understand their mechanical properties. The spicules display three distinct regions built of biosilica: (i) the outer lamellar zone (radius: >300 mu m), (ii) the bulky axial cylinder (radius: <75 mu m), and (iii) the central axial canal (diameter: <2 mu m) with its organic axial filament. The spicules are loosely covered with a collagen net which is regularly perforated by 7-10 mu m large holes; the net can be silicified. The silica layers forming the lamellar zone are approximate to 5 mu m thick; the central axial cylinder appears to be composed of almost solid silica which becomes porous after etching with hydrofluoric acid (HF). Dissolution of a complete spicule discloses its complex structure with distinct lamellae in the outer zone (lamellar coating) and a more resistant central part (axial barrel). Rapidly after the release of the organic coating from the lamellar zone the protein layers disintegrate to form irregular clumps/aggregates. In contrast, the proteinaceous axial barrel, hidden in the siliceous axial cylinder, is set up by rope-like filaments. Biochemical analysis revealed that the (dominant) molecule of the lamellar coating is a 27-kDa protein which displays catalytic, proteolytic activity. High resolution electron microscopic analysis showed that this protein is arranged within the lamellae and stabilizes these surfaces by palisade-like pillars. The mechanical behavior of the spicules was analyzed by a 3-point bending assay, coupled with scanning electron microscopy. The load-extension curve of the spicule shows a biphasic breakage/cracking pattern. The outer lamellar zone cracks in several distinct steps showing high resistance in concert with comparably low elasticity, while the axial cylinder breaks with high elasticity and lower stiffness. The complex bioorganic/inorganic hybrid composition and structure of the Monorhaphis spicules might provide the blueprint for the synthesis of bio-inspired material, with unusual mechanical properties (strength, stiffness) without losing the exceptional properties of optical transmission. (C) 2007 Elsevier Inc. All rights reserved.

Axial growth of hexactinellid spicules: Formation of cone-like structural units in the giant basal spicules of the hexactinellid Monorhaphis

The glass sponge Monorhaphis chuni (Porifera: Hexactinellida) forms the largest bio-silica structures on Earth; their giant basal spicules reach sizes of up to 3 m and diameters of 8.5 mm. Previously, it had been shown that the thickness growth proceeds by appositional layering of individual lamellae; however, the mechanism for the longitudinal growth remained unstudied. Now we show, that the surface of the spicules have towards the tip serrated relief structures that are consistent in size and form with the protrusions on the surface of the spicules. These protrusions fit into the collagen net that surrounds the spicules. The widths of the individual lamellae do not show a pronounced size tendency. The apical elongation of the spicule proceeds by piling up cone-like structural units formed from silica. As a support of the assumption that in the extracellular space silicatein(-like) molecules exist that associate with the external surface of the respective spicule immunogold electron microscopic analyses were performed. With the primmorph system from Suberites domuncula we show that silicatein(-like) molecules assemble as string- and net-like arrangements around the spicules. At their tips the silicatein(-like) molecules are initially stacked and at a later stay also organized into net-like structures. Silicatein(-like) molecules have been extracted from the giant basal spicule of Monorhaphis. Applying the SDS-PAGE technique it could be shown that silicatein molecules associate to dimers and trimers. Higher complexes (filaments) are formed from silicatein(-like) molecules, as can be visualized by electron microscopy (SEM). In the presence of ortho-silicate these filaments become covered with 30-60 nm long small rod-like/cuboid particles of silica. From these data we conclude that the apical elongation of the spicules of Monorhaphis proceeds by piling up cone-like silica structural units, whose synthesis is mediated by silicatein(-like) molecules. (C) 2008 Elsevier Inc. All rights reserved.

Effects of the amphibian skin-derived bradykinin B2 receptor antagonist peptide, kinestatin, on the proliferation of human prostate cancer cell lines

Bradykinin and related peptides are found in the defensive skin secretions of many frogs and toads. While the physiological roles of bradykinin-related peptides in sub-mammalian vertebrates remains obscure, in mammals, including humans, canonical bradykinin mediates a multitude of biological effects including the proliferation of many types of cancer cell. Here we have examined the effect of the bradykinin B2 receptor antagonist peptide, kinestatin, originally isolated by our group from the skin secretion of the giant fire-bellied toad, Bombina maxima, on the proliferation of the human prostate cancer cell lines, PC3, DU175 and LnCAP. The bradykinin receptor status of all cell lines investigated was established through PCR amplification of transcripts encoding both B1 and B2 receptor subtypes. Following this demonstration, all cell lines were grown in the presence or absence of kinestatin and several additional bradykinin receptor antagonists of amphibian skin origin and the effects on proliferation of the cell lines was investigated using the MTT assay and by counting of the cells in individual wells of 96-well plates. All of the amphibian skin secretion-derived bradykinin receptor antagonists inhibited proliferation of all of the prostate cancer lines investigated in a dose-dependent manner. In addition, following incubation of peptides with each cell line and analysis of catabolites by mass spectrometry, it was found that bradykinin was highly labile and each antagonist was highly stable under the conditions employed. Bradykinin signalling pathways are thus worthy of further investigation in human prostate cancer cell lines and the evidence presented here would suggest the testing of efficacy in animal models of prostate cancer as a positive outcome could lead to a drug development programme for the treatment of this disease.

Plasma cell polyp of the vocal fold

Plasma cell polyps of the vocal fold (plasma cell granulomas) are rare inflammatory polyps of the larynx. They should be included in the clinical and histological differential diagnosis of laryngeal polyps. Histologically they are polyclonal aggregates of plasma cells. It is essential to distinguish them from monoclonal, neoplastic plasma cell proliferations. The treatment of choice is surgical resection, although radiotherapy, laser ablation, antibiotics and steroids have been used successfully. We present a case of plasma cell granuloma presenting as a vocal fold polyp, treated surgically.

Morphometric analysis of corneal endothelial giant cells in normal and traumatized corneas

Corneal endothelial cells from normal and traumatized human, primate, cat and rabbit eyes were studied by specular microscopy. Morphometric analysis was performed on micrographs of corneal endothelium using a semi-automated image analysis system. The results showed that under normal conditions the corneal endothelium of all four species exhibit major morphological similarities (mean cell areas: human 317 +/- 32 microns 2, primate 246 +/- 22 microns2, cat 357 +/- 25 microns 2, rabbit 308 +/- 35 microns 2). The normal corneal endothelium in man was found to be more polymegethous than that of the other species. Trauma to cat, primate and human corneas resulted in a long-term reduction in endothelial cell density and enhanced polymegethism. In contrast, the reparative response of the rabbit ensured the reformation of an essentially normal monolayer following injury. Endothelial giant cells were a normal inclusion in the rabbit corneal endothelium but were only significant in cat, primate and man following trauma. The presence of corneal endothelial giant cells in amitotic corneas may therefore represent a compensatory response in the absence of mitotic potential.

Characterization of the mammalian homologs of the Drosophila Melanogaster Endocytic protein lethal (2) giant discs 1

Endocytose joue un rôle dans l'activation du récepteur Notch. Des mutations dans le gène drosophilien lethal giant discs (lgd), provoque une prolifération cellulaire en perturbant l'endocytose de Notch. Les orthologues murins mlgd1 et 2 peuvent sauver ce phénotype, démontrant une fonction conservée. Cependant, des publications récentes suggèrent que les orthologs humains de lgd (hgd1/2) sont nucléaires. Dans cette étude, il est démontré que chez la Drosophile, le mutant dlgd(08) provoque l'accumulation de Notch dans des vésicules et une surprolifération de neuroblastes . Ceci suggère que Notch est activé a l'intérieur des endosomes dans les neuroblastes. L'immunohistochimie de cellules Hela indique que hlgd1 et 2 ne sont pas nucléaires, mais associés à des strctures endosomales. Enfin, la baisse d'expression par shRNA des gènes murins mlgd1 et mlgd2 provoque une différenciation accélérée des cellules souches hématopoïétiques dans la lignée lymphopoïèse T et bloque la transition DN3 / CD4+CD8+, suggérant une suractivation de Notch.

Nitric oxide participation in granulomatous response induced by Paracoccidioides brasiliensis infection in mice

The role of nitric oxide (NO) in granulomas of Paracoccidioides brasiliensis-infected inducible NO synthase-deficient C57BL/6 mice (iNOS KO) and their wild-type counterparts and its association with osteopontin (OPN) and matrix metalloproteinases (MMPs) was studied. At 15 days after infection (DAI), iNOS KO mice showed compact and necrotic granulomas with OPN+ macrophages and multinucleated giant cells, whereas wild-type mice developed loose granulomas with many fungi and OPN+ cells distributed throughout the tissue. In addition, high OPN levels and fungal load were observed in iNOS KO mice. Both experimental groups had MMP-9 activity. At 120 DAI, iNOS KO had smaller granulomas with OPN+ cells, lower OPN levels, lower fungal load and decreased MMP-9 activity compared with wild-type mice. These findings suggest that NO has an important role in granuloma modulation, by controlling OPN and MMP production, as well as by inducing loose granulomas formation and fungal dissemination, resulting, at later phases, in progression of paracoccidioidomycosis.

Osteopontin involvement in granuloma formation and in the severity of Paracoccidioides brasiliensis infection

The participation of osteopontin (OPN) in Paracoccidioides brasiliensis infected mice, its association to granulomatogenesis, severity of infection, pattern of lesions, nitric oxide (NO) levels and fungal load were evaluated in this investigation. Immunohistochemistry analysis showed marked OPN staining in extracellular matrix and in macrophages and multinucleated giant cells at the center of lesions, suggesting a possible role of OPN in the distribution of these cells within the granulomas. At 15 days post-infection with a virulent P. brasiliensis isolate, OPN(+) cells were more numerous and intensely immunostained in the loose granulomas of susceptible mice than in those of resistant mice. In addition, high fungal loads and low NO levels were observed in susceptible mice. At 120 days after infection, resistant mice had increased total OPN levels (ELISA) and OPN positivity in compact granulomas, higher NO levels and lower fungal loads than susceptible mice. Residual lesions associated with low OPN levels, high NO and control of fungal dissemination were observed in both mouse strains at 120 days post-infection with the slightly virulent fungal isolate. Therefore, OPN could be associated with higher severity of the disease in an early phase of infection and with a degree of control of the progressive infection.

Vasodilator mechanisms in the dorsal aorta of the giant shovelnose ray, Rhinobatus typus (Rajiformes; Rhinobatidae)

This study investigated the nature of previous termvasodilator mechanismsnext term in the dorsal aorta of the giant shovelnose ray, Rhinobatus typus. Anatomical techniques found no evidence for an endothelial nitric oxide synthase, but neural nitric oxide synthase was found to be present in the perivascular nerve fibres of the dorsal aorta and other arteries and veins using both NADPH-diaphorase staining and immunohistochemistry with a specific neural NOS antibody. Arteries and veins both contained large nNOS-positive nerve trunks from which smaller nNOS-positive bundles branched and formed a plexus in the vessel wall. Single, varicose nNOS-positive nerve fibres were present in both arteries and veins. Within the large bundles of both arteries and veins, groups of nNOS-positive cell bodies forming microganglia were observed. Double-labelling immunohistochemistry using an antibody to tyrosine hydroxylase showed that nearly all the NOS nerves were not sympathetic. Acetylcholine always caused constriction of isolated rings of the dorsal aorta and the nitric oxide donor, sodium nitroprusside, did not mediate any dilation. Addition of nicotine (3×10−4 M) to preconstricted rings caused a vasodilation that was not affected by the nitric oxide synthase inhibitor, Image -NNA (10−4 M), nor the soluble guanylyl cyclase inhibitor, ODQ (10−5 M). This nicotine-mediated vasodilation was, therefore, not due to the synthesis and release of NO. Disruption of the endothelium significantly reduced or eliminated the nicotine-mediated vasodilation. In addition, indomethacin (10−5 M), an inhibitor of cyclooxygenases, significantly increased the time period to maximal dilation and reduced, but did not completely inhibit the nicotine-mediated vasodilation. These data support the hypothesis that a prostaglandin is released from the vascular endothelium of a batoid ray, as has been described previously in other groups of fishes. The function of the nitrergic innervation of the blood vessels is not known because nitric oxide does not appear to regulate vascular tone.

Possible role of bovine trophoblast giant cells in transplacental transmission of Neospora caninum in cattle

Neospora caninum is an aplicomplexan parasite that has brought several concerns to cattle raisers worldwide due to its relationship to fetal loss. However, the mechanism of the parasite's transplacental infection and induced abortions are not completely understood. Bovine trophoblastic binucleated cells (BNC) play a major role in the maternal-fetal interactions, migrating during the entire pregnancy from chorionic connections to uterine epithelium. This study aimed to investigate the possible role of BNC as phagocytic cells and its participation in the bovine transplacental infection of N. caninum. BNC was isolated by discontinuous Percoll gradient, and characterized by Hoeschst 33342 nucleus-specific staining. Isolated BNC were cultured in DMEM supplemented with 10% bovine fetal serum, and infected with 10(4) tachyzoites of N. caninum NC-1 strain. Parasite invasion was visualized by indirect immunofluorescence and Giemsa technique. Multiplication of parasites took place in 2-3 day cycles. Healthy cows' placenta and normal and infected cultured BNC was immunostained with monoclonal antibodies against CD-163, MAC-387 and NOS, demonstrating their phagocyte capacity. Thus, BNC was characterized as cells with macrophagic activity, which may host N. caninum in vitro. Therefore, we may conclude that BNC could potentially participate in the transplacental infection of bovine neosporosis.

Epidemiology, clinical signs, histopathology and molecular characterization of canine leproid granuloma: a retrospective study of cases from Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Intraosseous foreign-body granuloma in the mandible subsequent to a 20-year-old work-related accident

The purpose of this article was to describe the clinical and microscopic features of an intraosseous foreign-body granuloma in the mandible that developed after the traumatic implantation of metal fragments during a work-related accident. A 65-year-old male patient had a severe pain in the body of mandible. Clinical examination showed facial asymmetry and a scar, extending to the left mental region. Intraoral examination revealed a soft mass involving the left alveolar bone with normal appearance of the mucosa surface. Panoramic radiographs showed a radiolucent lesion along the mandible extending from the central incisive to the first molar. Computed tomography revealed an osteolytic mass in the same area. His medical history included a work-related accident twenty years prior to evaluation. During the biopsy an important amount of bright metal-like pieces surrounded by soft tissue were found. A microscopic examination showed a foreign body associated with an aggregation of multinucleated giant cells. The final diagnosis was a foreign body granuloma. Even though foreign-body granulomas in the mandible are rare lesions, dentists should be familiar with their features and include them in the differential diagnosis of tissue masses.

Imunoglobulinas e C3 no granuloma paracoccidióidico

Utilizou-se o modelo experimental de paracoccidioidomicose, em camundongos, induzida pela inoculação endovenosa de suspensão de formas cerebriformes do P. brasiliensis (cepa Bt2; 1x10(6) formas viáveis/animal), para avaliar, após 2, 4, 8, 16 e 20 semanas: 1. A presença de imunoglobulinas e C3 nos granulomas pulmonares, por imunofluorescência direta; 2. A resposta imune humoral (imunodifusão) e celular (teste do coxim plantar), e 3. A histopatologia das lesões. Os camundongos apresentaram resposta imunocelular positiva desde a 2a. semana, com depressão transitória na 16a. semana, e anticorpos desde a 4a. semana, com pico na 16a. semana. Os granulomas pulmonares foram epitelióides, com numerosos fungos e microabscesses; a extensão das lesões foi progressiva até a 16a. semana, com regressão discreta na 20a. semana. Desde a 2a. semana, houve deposição de IgG e C3 na parede dos fungos no interior dos granulomas e a presença de células IgG positivas no halo linfomononuclear periférico; estes achados foram máximos entre a 4a. e 16a. semanas. Não se detectou depósito de IgG e C3 no interstício dos granulomas. IgG e C3 parecem exercer papel precoce e importante na defesa do hospedeiro contra o P. brasiliensis, contribuindo possivelmente para a destruição dos fungos e bloqueando a difusão de antígenos para fora dos granulomas.

Correlation among immune response, morphogenesis of the granulomatous reaction and spleen lymphoid structure in murine experimental paracoccidioidomycosis

We studied the correlation among cellular immune response, the pattern of lung granulomatous lesions and alterations in spleen lymphoid structure in Swiss mice inoculated intravenously with Paracoccidioides brasiliensis strain 18. The animals were evaluated at 24, 48 and 96 h after infection and further studied weekly for 18 weeks by: (i) the macrophage migration inhibition test with phytohemagglutinin (PHA) and P. brasiliensis antigen (PbAg); and (ii) histopathology of the lung and spleen lesions. One group of animals was gamma -irradiated (8 Gy), infected under the same conditions and evaluated for the pattern of lung granulomatous lesions and spleen lymphoid structure at 24, 48 and 96 h after infection. During the first week of infection, the non-irradiated animals presented a positive response to PHA and PbAg, compact granulomas in the lungs and a typical hyperplasia of the spleen white pulp. However, from weeks 2 to 5, a depression of the cell-mediated immunity (CMI) response to PHA and PbAg was observed in association with granulomas presenting only large mononuclear cells and lacking both giant cells and a peripheral halo of small mononuclear cells. This pattern of granuloma formation was similar to that seen in gamma -irradiated animals, whose cells involved in CMI were absent. After week 7, the non-irradiated animals showed granulomas characterized by the presence of giant cells and a peripheral halo of small mononuclear cells. This type of granuloma was formed concomitantly with recovery of the CMI and of the lymphoid structure of the spleen. The results showed a correlation among granulomas composed of large mononuclear cells, hypoplasia of the splenic tissue and impaired CMI. This correlation indicated that although granuloma morphogenesis per se does not depend on the activation of CMI, this response is important at later stages during modulation of the cellular composition of the granulomas.

GRANULOMATOUS REACTION IN THE HAMSTER-CHEEK POUCH INDUCED BY KILLED PARACOCCIDIOIDES-BRASILIENSIS

We have studied the role of Paracoccidioides brasiliensis viability in the morphology of paracoccidioidomycotic granulomas in the hamster cheek pouch, an immunologically privileged site. Naive (N = 75) and previously sensitized (N = 50) two-month old male hamsters (Mesocricetus auratus) were inoculated into the pouch with 5 x 10(5) live or heat- or formalin-killed fungi. Previously sensitized animals presented a positive footpad test and immunodiffusion demonstrable antibodies (titer 1/32), at the time of sacrifice; naive animals were always negative for those immunological tests. The histological results showed that, like viable P. brasiliensis, killed fungi evoke typical epithelioid granulomas in 100% of animals, even in the absence of immunodiffusion or footpad test detectable immune response. The granulomas elicited by killed fungi were devoid of giant cells or a mononuclear cell halo, suggesting that live proliferating fungi or their products may be involved in these events.