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C Oura

Publications and source records attributed to C Oura.

At least 19 recordsLinked to original sources
PubMed1999

African swine fever virus: a B cell-mitogenic virus in vivo and in vitro.

The two major characteristics of pathogenesis in African swine fever virus (ASFV) infections of domestic pigs are massive B-cell apoptosis and haemorrhage. The effects of ASFV on porcine B cells have therefore been systematically examined in vivo, by using virus-infected pigs and SCID-Beige mice reconstituted with porcine bone marrow, and in vitro, by using porcine B-cell lines and B cells from normal and ASFV-infected pigs. Secretion of porcine Ig was stimulated by ASFV both in vivo and in bone marrow cultures in vitro, with the virulent Malawi isolate of ASFV being the most effective. Stimulation of Ig secretion in vitro depended on the presence of ASFV-infected macrophages and did not occur with supernatants from ASFV-infected macrophages. Although the virus alone did not stimulate proliferation of purified B cells in vitro, it was co-stimulatory with CD154 (CD40 ligand). The B cells recovered from ASFV-infected porcine lymphoid tissue were of activated surface marker phenotypes and, interestingly, expressed diminished levels of the B-cell co-stimulatory surface molecule CD21. In addition, they were highly sensitive to IL-4 and CD154. These results may be integrated into a model of pathogenesis in which those B cells activated indirectly as a result of virulent ASFV infection of macrophages are not rescued from apoptosis through interaction with CD154, due to the drastic depletion of T cells that occurs early in infection. The consequently diminished specific anti-ASFV antibody response would favour survival of the virus, with the non-specific hypergammaglobulinaemia being perhaps another example of pathogen-mediated immune deviation.

African Swine Fever↗
PubMed1993

Fine structural changes in the postacrosomal region of the hamster and mouse sperm head at the initial stage of gamete interaction in vivo.

This report documents ultrastructural changes in the postacrosomal region of the hamster and mouse sperm head at the initial stage of gamete interaction in vivo. Prominent structures were sequentially visualized: first, the periodic substructure crossbridging the postacrosomal sheath to the overlying plasma membrane, and then the small, electron-dense, granular structures lining the outer surface of the postacrosomal sheath. The periodic substructure became visible at the restricted region where the sperm plasma membrane was just prior to or in the act of detaching from the periodic substructure. The granular substances lined up along the external face of the postacrosomal sheath immediately after the detachment of the sperm plasma membrane, but before the complete degradation of the periodic substructure. These structural changes were completed before sperm nuclear decondensation started. The region where the granular structures were visualized was close to that of the antigen recognized by the monoclonal antibody MN13, which is supposed to be involved in the association of the periodic substructure with the overlaying plasma membrane (Toshimor et al., 1991). Based upon these results, we present the progress of events at the initial stage of gamete interaction.

Acrosome↗
PubMed1992

A rat sperm flagellar surface antigen that originates in the testis and is expressed on the flagellar surface during epididymal transit.

We identified a rat sperm flagellar surface antigen using an IgG1 monoclonal antibody (MC31) against rat epididymal sperm. Avidin-biotin-peroxidase immunohistochemistry demonstrated that the antigen was first expressed in the cytoplasm of early primary spermatocytes, then gradually became restricted to the principal piece of the sperm flagellum during spermatogenesis. However, when the sperm reached the corpus epididymidis, the antigen was expressed on the surface of both the principal piece and the midpiece of the flagellum. The epithelial cells of the epididymis were not stained with MC31. Immunogold electron microscopy showed that the antigen was present on the surface of the sperm flagellar plasma membrane. Immunoblotting of Triton X-100 extracts of epididymal sperm after one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing conditions demonstrated that MC31 detected a major antigen of 26,000-28,000 daltons (26-28K). Two-dimensional isoelectric focusing and SDS-PAGE indicated that the 26-28K antigen had an isoelectric focusing point (pl) of 5.8-5.3; minor antigens were also detected from 26K (pl 5.8) to 35K (pl 5.0). These results indicate that the antigen recognized by MC31 is an acidic 26-35K protein that originates in the testis, is integrated into the sperm flagellar plasma membrane of the principal piece during spermatogenesis, and then is expressed on the entire flagellar surface during epididymal transit.

Animals↗
PubMed1992

Appearance of an intra-acrosomal antigen during the terminal step of spermiogenesis in the rat.

In a survey of sperm antigens in the rat, a new intra-acrosomal antigen was found using a monoclonal antibody MC41 raised against rat epididymal spermatozoa. The MC41 was immunoglobulin G1 and recognized spermatozoa from rat, mouse and hamster. Indirect immunofluorescence with MC41 specifically stained the crescent region of the anterior acrosome of the sperm head. Immuno-gold electron microscopy demonstrated that the antigen was localized within the acrosomal matrix. Immunoblot study showed that MC41 recognized a band of approximately 165,000 dalton in the extract of rat sperm from the cauda epididymidis. Immunohistochemistry with MC41 demonstrated that the antigen was first detected in approximately step-2 spermatids, and distributed over the entire cytoplasmic region of spermatids from step 2 to early step 19. The head region became strongly stained in late step-19 spermatids and then in mature spermatozoa. Distinct immunostaining was not found in the developing acrosome of spermatids throughout spermiogenesis. These results suggest that the MC41 antigen is a unique intra-acrosomal antigen which is accumulated into the acrosome during the terminal step of spermiogenesis.

Acrosome↗
PubMed1992

Extra-Golgi pathway of an acrosomal antigen during spermiogenesis in the rat.

A monoclonal antibody (MC41) was produced that specifically recognizes a sperm acrosomal antigen of approximately 165,000 dalton in the rat. Rat testis was examined using a pre-embedding immunoperoxidase technique to reveal the pathway of the MC41 antigen to the acrosome during spermiogenesis. The MC41 immunoreaction appeared in several organelles of spermatids in a stage-specific manner: (1) in the endoplasmic reticulum (ER) throughout spermiogenesis, (2) in the outer acrosomal membrane from steps 9 to 19, (3) as a weak immunoreaction in the vesicular structures in the acrosomal matrix from steps 11 to 17, and (4) as a strong immunoreaction in the acrosomal matrix especially at the terminal step of spermiogenesis (step 19). However, no immunoreaction was observed in the Golgi region throughout spermiogenesis. These results suggest that the pathway of the MC41 antigen leads firstly from the ER to the outer acrosomal membrane and secondly to the acrosomal matrix. This pathway does not involve the Golgi apparatus and is referred to as the "extra-Golgi pathway".

Acrosome↗
PubMed1992

Characterization of the antigen recognized by a monoclonal antibody MN9: unique transport pathway to the equatorial segment of sperm head during spermiogenesis.

MN9, a monoclonal antibody raised against mouse spermatozoa, specifically recognizes the equatorial segment of sperm head in several mammalian species, including humans. Colloidal gold-immuno-electron microscopy of mouse spermatozoa has shown that the antigen is localized in the space between the outer and inner acrosome membranes and on the acrosome membranes at the equatorial segment. Immunoblotting after electrophoresis of spermatozoa from the cauda epididymidis has identified two immunoreactive bands: 38 kDa and 48 kDa in mouse, and 48 kDa in rat. During spermiogenesis in rat, this antigen is transported to the equatorial segment via a unique pathway, first appearing in some cisternae of the endoplasmic reticulum and in the Golgi apparatus of spermatids at around step 3. The antigen can further be found on the vesicles at the trans-side of the Golgi apparatus, in the matrix of the head cap, and on the head cap membrane in step-4 to step-7 spermatids. The antigen appears to be concentrated at the equatorial segment during late spermiogenesis. Neither the (pro-)acrosomic granule nor the surrounding membrane are required in this pathway. This pathway can be termed the 'Golgi-head cap tract'.

Acrosome↗
PubMed1992

Masking the cryptodeterminant on the 54-kilodalton mouse sperm surface antigen.

Previously, we reported that the epitope of a 54-kDa sperm surface sialoglycoprotein on the flagellum is masked by sialic acid residues. The epitope is referred to as a hidden determinant or cryptodeterminant. This paper reports the manner in which the epitope is masked as evaluated qualitatively and quantitatively by means of SDS-PAGE/immunoblots (Western blot) and ELISA. Immunoblotting with four specific monoclonal antibodies to the 54-kDa sialoglycoprotein--T21 (IgM), MC71 (IgG1), MC81 (IgM), and MC91 (IgM)--demonstrated that not only IgM but also IgG antibody MC71 and the Fab fragment MC71 are masked. Quantitative evaluation with ELISA to compare the antibody titration curves of the masked and unmasked antigens on sialidase-treated and untreated sperm, respectively, indicated that sialidase caused the antibody-binding ability of the epitopes to increase to a different level for each antibody. There were 32-256-, 8-16-, 16-, and 2-4-fold increases in binding to T21, MC71, MC81, and MC91 antibodies, respectively. These results suggest that the antigen-masking through the cryptodeterminant does not depend upon the subtype or the molecular mass of the antibody, but upon the biochemical nature of the epitope region that is closely related to the sialic acid. The mechanism and physiological roles of the antigen-masking are discussed.

Animals↗
PubMed1991

A monoclonal antibody, MN13, that recognizes specifically a novel substance between the postacrosomal sheath and the overlying plasma membrane in the mammalian sperm head.

Monoclonal antibody MN13 raised against mouse spermatozoa specifically recognizes the postacrosomal region of the sperm head in several mammalian species. Colloidal gold-immunoelectron microscopy of demembranated mouse spermatozoa indicated that the antigen is associated with the outer layer of the periodic substructure apparently linking the postacrosomal sheath to the overlying plasma membrane. The antigen recognized by MN13 may contribute to the intimate association of the postacrosomal sheath with the overlying plasma membrane.

Acrosome↗
PubMed1991

Artery anatomy and tortuosity in the distal finger.

The arterial architecture in the finger distal to the proximal interphalangeal joint was studied in sixty-seven cadaver fingers with the aid of an operating microscope. The course, frequency, location, and diameter of the dorsal nail fold artery and its anastomosis was recorded. Similar measurements were performed for the palmar anastomosis. The frequency of arterial tortuosity in the digital artery was compiled and a classification of its morphology devised. The characteristic of arterial tortuosity provides a degree of protection to these essential structures. Failure to recognize this facet of arterial anatomy may be one more factor contributing to our inability to successfully revascularize the distal finger in certain patients.

Arteries↗
PubMed1991

The distal venous anatomy of the finger.

An exhaustive anatomic dissection of all of the veins of the finger distal to the proximal interphalangeal joint was done. More than 3200 segments of veins were individually dissected out, measured, and recorded. From this survey new schematic diagrams have been drawn emphasizing the pertinent venous anatomy at the proximal, distal interphalangeal joints and eponychial levels. Suggestions are made for regions that are apt to have the largest vessels available for anastomosis.

Cadaver↗
PubMed1991

Digital artery tortuosity and elasticity: a biomechanical study.

The gross structure of the digital artery distal to the proximal interphalangeal joint is significantly different from its proximal portion. Previous research in this laboratory has revealed that over half of all fingers exhibit marked tortuosity of this artery in juxtaposition to the distal interphalangeal joint. Any structure with a large amount of bending will have the properties of a spring. An understanding of these properties may help in creating tension-free anastomoses during finger tip replantation. The elastic strength and energy storage capacities of the distal digital artery were measured in 26 cadaver arteries.

Arteries↗
PubMed1990

Chicken atrial natriuretic peptide (chANP) and its secretion.

An immunohistochemical study using antiserum raised against synthetic chicken natriuretic polypeptide was used to investigate the distribution of this peptide in the chicken heart. Immunoreactive cells, both in the atrial and ventricular walls, were identified by electron microscopy, and electron-dense granules in the atrial and ventricular cardiocytes were revealed to be storage sites of the peptide. The electron-dense material, thought to be the peptide, was found in the sarcoplasmic reticulum, and it is suggested that a secretory pathway of the peptide through the latter to extracellular space, may be present, in addition to an exocytotic one.

Aging↗
PubMed1990

Cryptodeterminant of a sperm maturation antigen on the mouse flagellar surface.

The determinant of a mouse sperm maturation antigen was examined morphologically and biochemically with monoclonal antibody T21 as a probe. The plasma membrane components of cauda epididymal spermatozoa were extracted with nonionic detergent Nonidet P-40 and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions and by immunoblotting. Wheat germ agglutinin-lectin staining and immunoblotting indicated that the antigen recognized by T21 is a sialoglycoprotein of about 54,000 daltons (54 kDa). The antigenic determinant was more distinctly exposed after treatment with neuraminidase, as evaluated by immunohistochemistry, immunocytochemistry, and immunoblotting. The cryptic nature of the determinant was further confirmed by immunostaining nitrocellulose strips, subsequently digesting the strips with neuraminidase, and then reimmunostaining them. Results obtained by periodate oxidation treatment suggested that the epitope is a carbohydrate. Immunoperoxidase electron microscopy confirmed that the antigen is distributed on the flagellar plasma membrane of the sperm. This was demonstrated clearly when sperm were desialylated with neuraminidase. These results indicate that the 54 kDa sialoglycoprotein sperm maturation antigen has a cryptodeterminant which can be masked by a sialic acid residue, that is recognized by monoclonal antibody T21.

Animals↗
PubMed1990

Epithelial cells with vacuoles containing 54,000 dalton sialoglycoprotein in the mouse epididymal duct.

Epididymal ligation in the mouse induced unusual cells, called peculiar pale epithelial cells (hereafter, pale cells), specifically in the epithelium of the corpus epididymidis (ABE et al., 1982a, b). These pale cells had vacuoles with long microvilli on their inner surface. In this study, we found that the vacuoles of the pale cells occurred in normal mice and contained epididymal specific glycoprotein, sialoglycoprotein of 54,000 dalton (SGP54). This was elucidated by indirect immunofluorescence and avidin biotin complex techniques using monoclonal antibody T21 which specifically recognizes SGP54. These immunoreactive pale cells occurred in the distal caput and proximal corpus of the epididymidis. The relationship between the pale cell and SGP54 is discussed.

Animals↗
PubMed1990

Immunohistochemical localization of 54,000 dalton sialoglycoprotein in the epididymal duct of the germ cell-free W/Wv mouse.

A monoclonal antibody T21 specifically recognizes the mouse epididymal sialoglycoprotein of 54,000 dalton (SGP54). The localization of SGP54 was studied in the epididymal duct of germ cell-free WBB6F1W/Wv mutant mice (W/Wv mice) by avidin biotin complex (ABC) immunohistochemistry using T21. None of the testis cells showed immunoreaction. No spermatozoa were present in the epididymal duct lumen. The duct luminal fluid was stained weakly in the proximal corpus epididymidis, and strongly in the cauda epididymidis. Degenerated cells appeared in the duct lumen. The degenerated cells located at the corpus epididymidis showed strong immunostaining in the cytoplasmic region, while the degenerated cells located at the cauda epididymidis showed weak immunostaining. Immunoreaction was also detected between and on microvilli along the epididymis, the intensity being very strong at the distal caput and proximal corpus epididymidis. Invaginations and coated vesicles at the luminal surface of the principal cells were frequently immunostained at the corpus epididymidis. Giant inclusions frequently occurred in the principal cells of the distal caput and corpus epididymidis, with these being very intensely immunostained. These inclusions are ultrastructurally confirmed to be giant multivesicular bodies reported by ABE et al. (1984) in the mouse with the efferent duct cutting. These results suggest that the majority of excess SGP54 are absorbed by the principal cells at the distal caput to corpus epididymidis and catalyzed in the giant multivesicular bodies.

Animals↗
PubMed1988

Distribution of atrial natriuretic polypeptide (ANP)-containing cells in the rat heart and pulmonary vein. Immunohistochemical study and radioimmunoassay.

The distribution of atrial natriuretic polypeptide (ANP) was immunohistochemically surveyed in the rat heart and lung using an antiserum raised against alpha-human ANP. The ANP-immunoreactive cells were seen to be distributed in the atrial walls and proximal portions of the pulmonary vein and venae cavae, but were absent from the aorta, pulmonary arteries, trachea, bronchus, and alveolar cells. The immunoreactive cells were present in a narrow region just beneath the endothelium of the pulmonary vein and vena cavae, and, ultrastructurally and immunocytochemically, were seen to be striated muscle cells with ANP-containing specific granules similar to those seen in atrial cardiocytes. A radioimmunoassay for ANP revealed a content of 604 +/- 51 pg/mg wet weight in the pulmonary vein, and 3343 +/- 1620 pg/mg wet weight in the venae cavae. In addition to the atrial wall, the proximal portion of both the pulmonary vein and venae cavae are suggested to be constituents of an ANP-producing organ.

Animals↗