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Biomedical subjects

R Sullivan

Publications and source records attributed to R Sullivan.

At least 73 records · Page 4Linked to original sources
PubMed1996

Cases of human infertility are associated with the absence of P34H an epididymal sperm antigen.

The interaction of spermatozoa with the zona pellucida is a critical step of fertilization. Specific sperm surface proteins involved in this process can be added or modified during epididymal transit. We have previously described a 34-kDa human epididymal sperm protein (P34H) that we proposed to be involved in sperm-zona pellucida interaction. In this study, Western blot analysis were performed to determine the level of P34H protein present on the spermatozoa of 16 men with idiopathic infertility. These levels were compared with the amount of P34H protein found in men of proven fertility. In addition, a sperm-zona pellucida binding assay was performed with spermatozoa from fertile and infertile men. Spermatozoa obtained from different semen samples from a given individual had similar P34H levels. However, the amount of P34H varied from one man to another. Nine of 16 infertile men had a P34H level that was less than 30% of the normal value based on a population of fertile men, while the remaining 7 males were in the normal range. Sperm from infertile subjects with a normal P43H determination bound to zonae pellucidae as efficiently as those from controls. However, spermatozoa from subjects with a low amount of P34H exhibited a dramatic diminution in their ability to interact with zonae pellucidae. Our results show that the quantity of the epididymal protein P34H varied from one male to another and that low levels of this epididymal sperm protein are associated with certain cases of idiopathic infertility. Results are discussed with regard to the function of human epididymis in sperm maturation.

Adult↗
PubMed1996

Purification of P26h: a hamster sperm protein.

P26h is a 26 kDa glycoprotein, located on the acrosome cap of hamster spermatozoa, involved in the species specificity of gamete interaction. We have purified this protein from hamster spermatozoa collected from the distal cauda region of the epididymis. Its purification was realized following a three-step procedure: detergent extraction, ion-exchange chromatography, and chromatofocusing. Protein partitioning using Triton X-114 (the first step) showed a ratio of 5:1 between the resulting aqueous and detergent phase. P26h was found almost exclusively in the aqueous phase where it represented about 10-12% of the total protein content. When the desalted aqueous phase was loaded on a carboxymethyl column for cation-exchange chromatography, about 80% of the proteins did not bind to the matrix and were eliminated. P26h was eluted from the column with a linear gradient of salt. At this point, P26h had a rate of purification estimated at 45-55%; three other major proteins of <21, 45, and 63 kDa remained in the sample. These undesired proteins were eliminated by submitting these samples to chromatofocusing using a PBE 94 polybuffer exchanger column. Indeed, P26h was collected almost in the dead volume of the column while the other proteins were eluted much later. Two-dimensional gel electrophoresis and Western blotting were performed to determine the purity of P26h. Only one major spot was detected, confirming the purity of P26h. Usefulness of this purified sperm antigen in the understanding of the physiology of mammalian fertilization is discussed.

Animals↗
PubMed1996

The identity and work of the ancient Egyptian surgeon.

That a well-developed and hierarchical medical profession existed in Pharaonic Egypt is without doubt. What is a matter of contention is the existence of a recognizable surgical profession, or even of the practice of surgery by medically qualified personnel. Palaeorchaeological specimens that demonstrate some form of surgical procedure are rare. Medical papyri and the treatises of the historians of antiquity provide a far more reliable source of information on surgical practice. They have indicated possible titles for surgeons, and the types of instruments used.

Egypt, Ancient↗
PubMed1996

The hazards of reproduction in space.

NASA Medical Standards for space flight (JSC 11570) specifically disqualify any flight crew member who is pregnant. A variety of factors led to this recommendation including the effects of radiation exposure on fetal development. Additionally, other concerns such as toxic chemical exposure, microgravity, pregnancy accidents, plus alterations in breathing gas mixtures and decompression preclude pregnant flight crew members from missions in the foreseeable future. The future of space travel will require reproduction beyond the confines of earth's environment. This makes it all the more necessary to identify the potential hazards associated with reproduction in space.

Aerospace Medicine↗
PubMed1995

Comparative immunoreactivity of mouse and hamster sperm proteins recognized by an anti-P26h hamster sperm protein.

The binding of the spermatozoon to the zona pellucida is a species-specific phenomenon. We have previously shown that the binding of hamster sperm to the homologous zona pellucida involves a sperm 26-kDa glycoprotein, the P26h, originating in the epididymis. In order to establish to what extent this sperm protein is involved in the species-specific recognition of the egg's extracellular coat, we have compared the inhibitory properties of anti-P26h antibodies in a sperm-zona pellucida assay using hamster and mouse gametes. Anti-P26h IgGs inhibit, in a dose-dependent manner, gamete interactions in both species, although in a less efficient manner in the mouse than in the hamster. While anti-26kDa Fab fragments are as efficient as the intact IgG to inhibit hamster sperm-zona pellucida binding, they have no effect on mouse gamete interaction. ELISA, Western blot, and immunohistochemical experiments have been performed in order to characterize the mouse antigen(s) recognized by the anti-P26h antiserum. ELISA and Western blots showed that this antiserum recognized two proteins on mouse spermatozoa that are less reactive than the hamster P26h. These antigens are localized in the acrosomal region of epididymal spermatozoa of both species. These results indicate that the hamster P26H involved in zona pellucida interaction has certain unique epitopes, while others are common to the sperm of both species.

Animals↗
PubMed1995

Expression of a connexin 43/beta-galactosidase fusion protein inhibits gap junctional communication in NIH3T3 cells.

Gap junctions contain membrane channels that mediate the cell-to-cell movement of ions, metabolites and cell signaling molecules. As gap junctions are comprised of a hexameric array of connexin polypeptides, the expression of a mutant connexin polypeptide may exert a dominant negative effect on gap junctional communication. To examine this possibility, we constructed a connexin 43 (Cx43)/beta-galactosidase (beta-gal) expression vector in which the bacterial beta-gal protein is fused in frame to the carboxy terminus of Cx43. This vector was transfected into NIH3T3 cells, a cell line which is well coupled via gap junctions and expresses high levels of Cx43. Transfectant clones were shown to express the fusion protein by northern and western analysis. X-Gal staining further revealed that all of the fusion protein containing cells also expressed beta-gal enzymatic activity. Double immunostaining with a beta-gal and Cx43 antibody demonstrated that the fusion protein is immunolocalized to the perinuclear region of the cytoplasm and also as punctate spots at regions of cell-cell contact. This pattern is similar to that of Cx43 in the parental 3T3 cells, except that in the fusion protein expressing cells, Cx43 expression was reduced at regions of cell-cell contact. Examination of gap junctional communication (GJC) with dye injection studies further showed that dye coupling was inhibited in the fusion protein expressing cells, with the largest reduction in coupling found in a clone exhibiting little Cx43 localization at regions of cell-cell contact. When the fusion protein expression vector was transfected into the communication poor C6 cell line, abundant fusion protein expression was observed, but unlike the transfected NIH3T3 cells, no fusion protein was detected at the cell surface. Nevertheless, dye coupling was inhibited in these C6 cells. Based on these observations, we propose that the fusion protein may inhibit GJC by sequestering the Cx43 protein intracellularly. Overall, these results demonstrate that the Cx43/beta-gal fusion protein can exert a dominant negative effect on GJC in two different cell types, and suggests that it may serve as a useful approach for probing the biological function of gap junctions.

3T3 Cells↗
PubMed1995

New directions for research in prevention and treatment of delinquency: a review and proposal.

The past century has witnessed a number of approaches to the prevention and treatment of delinquency. Some approaches have emphasized physiological, psychological, and other individual characteristics; others have focused on the structure of the family; and still others have considered the structure of social relations within the broader society. More recent approaches have attempted to conceptualize an integrated complex of factors which includes community characteristics. This article reviews the various approaches which have dominated the field over the last few decades and concludes with a methodological proposal which may facilitate the systematic consideration of these various factors.

Adolescent↗
PubMed1995

A brief journey into medical care and disease in ancient Egypt.

Ancient Egypt was one of the greatest civilizations to have arisen, becoming the cradle of scientific enquiry and social development over 3 millennia; undoubtedly its knowledge of medicine has been vastly underestimated. Few artefacts survive which describe the medical organization, but from the extent of the diseases afflicting that ancient populus there would have been much to study. Evidence from papyri, tomb bas reliefs and the writings of historians of antiquity tell of an intense interest in the sciences, humanities and medicine born of an educated society which had overcome the superstitions of its nomadic ancestors.

Achondroplasia↗
PubMed1994

Induction of polyspermy in sea urchin eggs by antibodies raised against a hamster sperm protein.

Polyclonal antibodies raised against a hamster sperm protein (P26h) induce polyspermic fertilizations in the green sea urchin without affecting the fertilizing ability of the spermatozoa nor the elevation of the fertilization membrane. While the adsorption of the antibodies on sperm decreased the polyspermic effect, preincubation of unfertilized eggs with the anti-P26h did not cause polyspermy. These results suggest that common epitopes are involved in fertilization processes in phylogenetically distant species.

Animals↗
PubMed1994

Expression of fibronectin and a fibronectin-binding molecule during preimplantation development in the mouse.

Using an indirect immunofluorescent technique, expression of cell surface fibronectin and a cell surface fibronectin-binding molecule was studied during mouse embryo preimplantation development. We also studied the expression of fibronectin on immunosurgically isolated inner cell masses (ICMs) and regenerated mouse blastocysts. Fibronectin and the fibronectin-binding molecule were not detected at the morula stage. From the early to late blastocyst stage, fibronectin expression increased on the trophectoderm. Expression of the fibronectin-binding molecule was found only in the polar trophectoderm region of the early blastocyst, then in the polar and mural trophectoderm regions of the middle blastocyst. In the late blastocyst stage, this fibronectin-binding molecule was only present in the mural trophectoderm. Fibronectin expression by ICMs of early blastocysts was more intense than that of late blastocysts. After 24 h of culture, 10% of ICMs isolated from early blastocysts regenerated a trophectoderm which stained intensively for fibronectin in the mural and polar trophectoderm regions. After 48 h of culture, regenerated blastocyst-like structures closely resembled the normally obtained late blastocysts and stained for fibronectin in the mural and polar trophectoderm regions. The significance of the results is discussed in relation to mouse embryo development, trophectoderm formation and blastocyst implantation.

Amino Acid Sequence↗
PubMed1994

Human sperm-zona pellucida interaction is inhibited by an antiserum against a hamster sperm protein.

During epididymal transit, mammalian spermatozoa acquire new surface antigens that may participate in gamete interaction. We have previously described a 26-kDa (P26h) epididymal hamster sperm protein that we propose to be involved in fertilization. In this study, we have searched for an antigenically related protein in the human, and have found that an anti-P26h antiserum recognizes a 34-kDa (P34H) protein on Western blot of human sperm proteins. Immunostaining showed that this protein is localized on the acrosomal cap of human epididymal spermatozoa but not on testicular gametes. The effect of the anti-P26h antiserum on the fertilizing ability of human spermatozoa was evaluated by use of a human zona pellucida binding assay. Compared to the preimmune serum, the antiserum caused a highly significant decrease in the number of sperm bound per zona pellucida. This inhibition was not due to the induction of a premature acrosomal reaction nor to an effect on the motility of the spermatozoa. The antiserum recognizing the P34H human sperm protein had no effect on gamete fusion as determined by the zona-free hamster test. Our results suggest that the human spermatozoon acquires an epididymal protein that shares a common epitope(s) with the P26h hamster sperm protein. The possible involvement of this human sperm antigen in the binding to the zona pellucida is discussed.

Acrosome↗
PubMed1994

Inhibition of in vivo fertilization by active immunization of male hamsters against a 26-kDa sperm glycoprotein.

We have identified a 26-kDa (P26h) epididymal hamster sperm glycoprotein with a species-specific affinity for zona pellucida glycoprotein. Two immunological procedures have been used to document the biological function of this sperm component; active immunization of males against P26h and inhibition of sperm-zona pellucida binding in vitro by anti-P26h antibodies. The immunized male hamsters produced circulating antibodies specific to P26h. Indirect immunofluorescence studies showed that these antibodies bind to the surface of the sperm covering the acrosome. These males were mated with superovulated females, and although spermatozoa were recovered from the genital tract, none of the 194 oocytes recovered were fertilized. In contrast, control males immunized with hamster albumin fertilized 97.4% of the oocytes. Unlike control spermatozoa, those recovered from the cauda epididymidis of males immunized with P26h were characterized by the presence of antibodies at the surface of the acrosome. To establish whether the inhibition of in vivo fertilization by active immunization was occurring at the level of sperm-zona pellucida interaction, a polyclonal antiserum against P26h was raised, and the IgG fraction was added to an in vitro sperm-zona pellucida assay. Compared to the preimmune serum, the IgG inhibited the binding of spermatozoa in a dose-dependent manner. The Fab fragments generated from these IgGs were almost as efficient in inhibiting the binding. These results are discussed with regard to a possible function of P26h in hamster gamete interaction.

Acrosome↗