PubMed Health⌕ Search

Biomedical subjects

C Azevedo

Publications and source records attributed to C Azevedo.

At least 37 records · Page 2Linked to original sources
PubMed1999

Nail changes secondary to docetaxel (Taxotere).

Docetaxel is a new taxoid antineoplastic drug widely used for advanced breast cancer. Skin and nail toxicity are one of the more frequent nonhematologic adverse reactions. Besides dark pigmentations and Beau's lines, subungual hemorrhage, orange discoloration, acute painful paronychia, onycholysis, subungual hyperkeratosis and transverse loss of the nail plate are described. The type of nail alteration is related with the number of cycles administered and there are no efficacious preventive measures to avoid its development. Clinicians should recognize the clinical picture of these adverse nail reactions because docetaxel is used for several neoplastic disorders.

Adult↗
PubMed1997

Morphological characterization of the hemocytes of the clam, Ruditapes decussatus (Mollusca: Bivalvia).

Hemocytes play an important role in internal defence in molluscs. The morphology of hemolymph cells was studied for the first time in Ruditapes decussatus. Two main types of hemocytes (hyalinocytes and granulocytes) exist in R. decussatus. Three types of granulocytes were identified by light microscopy, in accordance with the presence of basophilic or acidophilic granules or a mixture of both in the cytoplasm. The existence of hyalinocytes and granulocytes was confirmed by electron microscopy. Some monoclonal antibodies (MABs) raised against hemocytes of Crassostrea gigas showed cross-reactivity with the total population of hemocytes of R. decussatus; however, none of the MABs raised against hemocytes of Mytilus edulis showed cross-reactivity. The MABs assayed did not allow us to distinguish hemocyte subpopulations.

Animals↗
PubMed1997

Enzymes Involved in Defense Functions of Hemocytes of Mussel Mytilus galloprovincialis

Mytilus galloprovincialis hemocytes contain phosphatases, esterases, proteases, and glucosidases as revealed by a semiquantitative colorimetric method. The activity levels of some enzymes changed throughout the months of the experiment without a seasonal pattern. No differences in the enzyme levels were found between the two groups of mussels of different age (cultivated 11 and 19 months on ropes hung from the same raft). Light microscopy study of hemocyte enzymes showed that hyalinocytes and granulocytes had reaction of acid phosphatase, beta-glucuronidase, alpha-naphthyl butyrate esterase, naphthol AS-D chloroacetate esterase, and alpha-naphthyl acetate esterase. Phenoloxidase and peroxidase activities were also detected in monolayers of hemocytes. Ultrastructural study revealed that the granules of hemocytes contained acid phosphatase, beta-glucuronidase, nonspecific esterases, peroxidase, and NADH oxidase. Products of beta-glucuronidase and peroxidase reaction were also localized in the plasma membrane. Lysozyme activity level was higher in hemocytes than in serum. Comparison between the two groups of different age showed a higher activity level of lysozyme in younger mussels.

Journal Article↗
PubMed1996

Henneguya malabarica sp. nov. (Myxozoa, Myxobolidae) in the Amazonian fish Hoplias malabaricus.

Henneguya malabarica sp. nov. is described from the Amazonian teleost fish Hoplias malabaricus Boch, 1794, collected from the estuarine region of the Amazon river near Belém, Brazil. Plasmodia were represented by several vegetative nuclei, generative cells, and sporogony stages contained in cyst-like plasmodia. The spore body was ellipsoidal (12.6 microns in length and 4.8 x 3.6 microns in width) and each valve presented a tapering tail (17.1 microns in length). Thin valves surrounded the binucleate sporoplasm cell and two spherical polar capsules (3.7 x 1.8 microns) that contain five to six coils of the polar filament. The spore had an iodinophilous vacuole. The basal portion of the spore body of immature and mature spores and the whole surface of the tails were surrounded by a close homogeneous sheath. The prevalence of infection was 6.7% in the fish examined. The spores differed from those of previously described species of Henneguya in their shape, size, spore, and arrangement of the polar-filament coil. The taxonomic affinities of this parasite to other species are discussed.

Animals↗
PubMed1996

Light and electron microscopic study of a myxosporean, Tetrauronema desaequalis n. sp. (fam. Tetrauronematidae), from an Amazonian fish.

Tetrauronema desaequalis n. sp. described from the bases of the ventral fins of the teleost Hoplias malabaricus Boch, 1794, was collected in an estuarine region of the Amazon river near Belem, Brazil. This myxosporean produces large cysts (1-2 mm in diameter) that represent plasmodia containing all life cycle stages, including spores. Spores averaged 22.5 microns in total length and possess 2 pairs of posterolateral unequal projections extending from beside the sutural ridges near the terminus of the shell valves. The spore body was ellipsoidal and laterally compressed. Spore bodies measured 13.6 microns in length, 6.5 microns in width, and 3.7 microns in thickness. The 4 projections averaged 13.0, 12.2, 7.2, and 5.1 microns in length. The ellipsoidal polar capsules (7.0 x 2.6 microns) possessed a polar filament with 9-11 turns.

Animals↗
PubMed1993

Processing of food vacuoles in the parasitic ciliate Ichthyophthirius multifiliis after exit from the host.

The digestive cycle of the fish parasite Ichthyophthirius multifiliis (Ciliophora) can be divided into three main stages. During stage A the vacuoles are not yet condensed. This stage can be subdivided into an early phase in which food vacuoles contain almost intact fish cells and a later phase in which dense material accumulates at the periphery of the vacuoles. At stage B, food vacuoles attain a very high density, and at stage C the vacuole expands when the membrane pulls away from a condensed mass of substances in digestion. After its exit from the host the parasite encysts and divides, but new food vacuoles are not formed during this phase of the life cycle. Type A vacuoles are the first to disappear after exit from the host. The percentage of type B vacuoles increases during the first few hours of free life, decreasing later when the percentage of type C vacuoles starts to increase. At the end of the division phase, type C vacuoles are the most common. Food-vacuole egestion was observed only 20 h after exit from the host. At the theront stage, food vacuoles were not evident, but small vacuoles with acid phosphatase activity were observed.

Animals↗
PubMed1992

Presence of a trypsin-like protease in starfish sperm acrosome.

Marthasterias glacialis sperm cells were treated with ionophore A23187, centrifuged, and the supernatants were assayed for esterase activity. With N-benzoyl-L-arginine ethyl ester-HCl (BAEE) as substrate, a net activity was determined which was not detectable when N-acetyl-L-tyrosine ethyl ester (ATEE) was used. The BAEE trypsin-like activity was inhibited by soybean trypsin inhibitor (SBTI), N-alpha-p-tosyl-L-lysine chloromethyl ketone-HCl (TLCK), and phenyl methyl sulfonyl fluoride (PMSF), but not by L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK). The presence of proteolytic activity in acrosomal exudates was further demonstrated by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoretic zymography (gelatin-SDS-PAGE). The presence of several bands of low proteolytic activity and of one band of high proteolytic activity, which also has the lower molecular weight, together with the fact that all are inhibited by benzamidine, suggests the existence of a trypsin-like proteinase system. The effect of the acrosomal exudate on the oocyte jelly coat was investigated by SDS-PAGE analysis. All jelly proteins appeared to be digested by the acrosomal enzymes. Furthermore, if SBTI is added shortly after insemination, the sperm fail to fertilize the oocytes. These results indicate that the starfish sperm acrosomal vesicle contains a trypsin-like protease which may be involved in sperm penetration through the oocyte jelly coat.

Acrosome↗
PubMed1992

Silver staining of the postacrosomal sheath during human spermiogenesis.

Applying the silver staining technique, it could be shown that in the early phase of spermiogenesis a layer of argyrophilic material accumulated at the base of the acrosomal vesicle and at the outer side of the nuclear envelope opposite that region, and, later, at the inner side of the plasma membrane near the base of the acrosomal vesicle. During further development of the postacrosomal region of the spermatozoon head, the argyrophilic material associated with the plasmalemma grew caudally to form the postacrosomal dense lamina, while the argyrophilic material associated with the nuclear envelope, staying the same size, shifted to the caudal end of the postacrosomal dense lamina to form the post-nuclear band.

Humans↗
PubMed1991

Extracellular giant rickettsiae associated with bacteria in the gill of Crassostrea gigas (Mollusca, Bivalvia).

Extracellular giant rickettsiae closely associated with bacteria with a Gram-negative type wall are reported among the basal insertions of the cilia of the gill epithelium of the oyster Crassostrea gigas (Mollusca, Bivalvia) from the north of Spain. These rickettsiae are extremely pleomorphic cells with a maximum 9 microns length. The internal elements are ribosome-like particles and DNA strands are distributed in some light areas. Some rickettsial cells show one to two vacuole-like dense inclusions formed by curved concentric bands approximately 4 nm thick separated by an approximately 5-nm light space (myelin-like bodies). Numerous bacteria are closely associated with the rickettsiae in the surrounding zone. The cytopathic effects of this association seemed to give rise to the epithelial lysis and concomitant disappearance of the apical microvilli and cilia and the consequent destruction and disintegration of the gill epithelial cells, where these rickettsiae live in close proximity. This is believed to be the first description of extracellular giant pathogenic rickettsiae of these oyster species.

Animals↗
PubMed1990

Fine structure of zoosporulation in Perkinsus atlanticus (Apicomplexa: Perkinsea).

Light and transmission electron microscopy were used to study different stages of Perkinsus atlanticus (Apicomplexa) during induced zoosporulation, with fluid thioglycollate medium and seawater. Cytokinesis and nucleokinesis of different developmental stages were studied every 12 h during the incubation period of 72 h, at which time the zoospores became free. Uninucleated and flagellated zoospores present the apical complex formed by conoid, polar ring, micronemes, rhoptries and subpellicular microtubules observed at different sections. Ultrastructural details were compared with the other two species of the genus Perkinsus.

Animals↗
PubMed1989

Ultrastructural and cytochemical study of spermatogenesis in Scrobicularia plana (Mollusca, Bivalvia).

The ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome-like junctions, elongated spermatids are held at the acrosomal region by support cell finger-like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 microns. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications.

Acid Phosphatase↗
PubMed1989

Starfish sperm-oocyte jelly binding triggers functional changes in cortical granules. A study using acid phosphatase and ruthenium red ultrastructural histochemistry.

Starfish oocytes were examined before fertilization, immediately after insemination, and during the cortical reaction by means of acid phosphatase and ruthenium red ultrastructural histochemistry. Oocyte cortical granules are composed of a lamellar body and a surrounding matrix which is subdivided into dense and light portions. In unfertilized oocytes cortical granules are not stained by ruthenium red but show a weak acid phosphatase activity in the light portion of the granule matrix. Immediately after the adhesion of the spermatozoon to the oocyte jelly coat, the light matrix portion of cortical granules appears stained by ruthenium red and shows a strong acid phosphatase activity. During the cortical reaction, cortical granules are released into the perivitelline space and the lamellar body, surrounded by the stained matrix, fuses with the fertilization envelope. Our data suggest that membrane permeability changes and enzyme activation occur in the egg when the spermatozoon binds to the oocyte jelly coat.

Acid Phosphatase↗
PubMed1989

Some ultrastructural data on the spore development in a Henneguya sp. parasite of the gill of a Brazilian fish.

A myxosporean Henneguya sp. was found in the gill filaments of a freshwater fish, Hoplosternum littorale, from the lower Amazon river near Belém, Brazil. Plasmodia were represented by numerous vegetative nuclei, generative cells and sporogony stages. The spore body was ellipsoidal and each valve presented a tapering tail approximately 45.2 microns in length. The spores differed from those of previously described species in their shape and size. The developmental stages are described and discussed. This histozoic species is reported to be pathogenic, inducing great mortality in the host.

Animals↗
PubMed1989

Fine structure of Perkinsus atlanticus n. sp. (Apicomplexa, Perkinsea) parasite of the clam Ruditapes decussatus from Portugal.

A new apicomplexan species, Perkinsus atlanticus, is described from gill filaments of the clam Ruditapes decussatus (Bivalvia) from Portugal, where it causes great mortality. The zoospores differ from those of other species of Perkinsus in size and shape, dimensions, insertion of the 2 flagella, and in the identity of the host. On the other hand, the life cycle stages showed some ultrastructural differences compared with Perkinsus marinus, the only species previously studied in detail. When the clams were parasitized heavily, ultrastructurally similar life cycle stages were found in foot and mantle tissues.

Animals↗
PubMed1988

Presence of ATPase and alkaline phosphatase activities in the starfish sperm acrosome.

ATPase activity was cytochemically detected in the peripheral acrosomal component of ionophore-reacted sperm, while alkaline phosphatase activity was demonstrated in the upper and central components of the acrosome and, at fertilization, at the site of sperm-oocyte binding. Supernatants of ionophore treated sperm suspensions were assayed for ATPase, alkaline and acid phosphatase activities. Results suggest that alkaline phosphatase may be involved both in the acrosomal reaction and oocyte jelly lysis but the function of the acrosomal ATPase remains unknown.

Acrosome↗
PubMed1988

Presence of argyrophilic cytoplasmic and nuclear proteins in the spermatic cells of Nucella lapillus (Gastropoda, Prosobranchia).

The technique for ultrastructural localization of argyrophilic proteins was modified and NOR-Silver staining methods were applied to the study of the distribution of these proteins in the spermatic cells of Nucella lapillus (Gastropoda, Prosobranchia). Two types of selective silver deposits were found during the different phases of spermiogenesis and in mature spermatozoa. Argyrophilic nuclear, nucleolar and cytoplasmic proteins were simultaneously detected by improvement of a modified one-step silver technique.

Animals↗
PubMed1988

Starfish acrosomal acid phosphatase: a cytochemical and biochemical study.

The acrosome reaction of spermatozoa from the starfish Marthasterias glacialis was induced with the ionophore A23187. Reacted cells were then processed for acid phosphatase ultrastructural cytochemistry, but significant enzyme activity was not detected. However, when the supernates from suspensions of ionophore-treated sperm were assayed for acid phosphatase, a net enzyme activity was observed. Supernatant proteins were run in starch gel electrophoresis and fluorescent zymograms revealed a single band of acid phosphatase. SDS-PAGE of proteins eluted from the active spots of starch gels showed one major band of about 63 kDa. The results obtained support the hypothesis that the acid phosphatase whose activity has been detected only at the time of binding of sperm and egg originates from the sperm acrosome.

Acid Phosphatase↗