Sperm antibodies in vasectomized men and their effects on fertilization

Sera (vbs, n = 25) and seminal plasma (vsp, n = 21) from vasectomized men (n = 25) were analyzed for cross-reaction with lithium diiodosalicylate (LIS)-solubilized human sperm extract, protamine, and fertilization antigen (FA-1) with an enzyme-linked immunosorbent assay (ELISA). Among the vbs tested, 44% reacted with human sperm extract, 28% reacted with protamine, and 44% reacted with FA-1 for at least one class of antibodies (IgG, IgA, or IgM). In contrast to the sera, the seminal plasma showed minimal reactions. Neither the vbs nor vsp were found to contain immune complexes, indicating that the antibodies were present in free form. Vasectomized sera that reacted with FA-1 showed a significant (p less than 0.0001) inhibition of human sperm penetration of zona-free hamster ova. The immunoabsorption of FA-1-positive sera with purified FA-1 significantly increased the penetration rates. Affinity-purified human immunoglobulins reactive with FA-1 and not those reactive with protamine reduced sperm penetration rates. Thus, antibodies in vbs reactive with FA-1 are relevant to infertility, causing an inhibition of fertilization. These data will have clinical relevance for diagnosis and treatment of infertility after successful vasovasostomy.     

Antifertility effects of immunoglobulins from uterine fluids of semen-immunized rabbits

The effects on fertility of the immunoglobulins, IgG (similar to serum IgG) and secretoy IgA (the predominant IgA in uterine fluid, different from serum IgA) and the fluids from the uteri of semen-immunized rabbits were studied. Female rabbits were immunized either by transvaginal (TV) injections (every 4 or 5 days for 3 weeks) with adjusted semen added to buffered saline containing .5 mg each polyadenylic acid )Poly-A) and polyuridylic acid or a combination of transvaginal injections and systemic injections with rabbit semen mixed with adjuvant (each once weekly for 3 weeks). 2 weeks following the last injection of semen each rabbit received a TV injection followed in 1 week by an instillation of semen and Poly A and U into uterine horns ligated at both ends. 2 weeks following intrauterine (IU) instillation uterine contents were withdrawn. Uteri were reinstilled. Passive hemagglutinating (PHA) and sperm-immobilizing antibody titers were determined on both serum and adjusted uterine fluid (UF) samples. Sperm immobilizin tests and PHA were positive in all serum samples from the contained immunization group, and PHA were positive in 4 out of 7 UF samples of this group. 2 out of 10 and 3 out of 10 samples from the TV group were positive for SI and PHA, respectively, and 4 out of 10 UF samples were PHA positive. Treatment of rabbit semen with UF samples prior to insemination of estrous rabbits resulted in an implantation rate of 2.8% for the combined immunization group and 24.2% for the TV group compared to 79.2% for controls. Some IUF samples without detectable antibodies appeared to inhibit fertility. The implantation rate of sperm treated with immune UF from the TV group absorbed with goat normal serum, anti-rabbit gamma-globulin serum, anti-rabbit-secretory IgA serum, anti-rabbit IgG serum, or sperm, were 3.4%, 88.9%, 42.9%, 64%, and 73. 3% respectively. SIgA and IgG antibodies were seperated by gel filtration. 2 of 4 pooled IgA samples and 3 of 4 pooled IgG samples depressed fertility, with 24.3% and 22.6% implantation and 25.8% 5, and 0% implantation, respectively. To assure that the antifertility effects observed were due to sperm antibodies of each immunoglobin class, SIgA fractions of 2 IUF pools were subjected to anion-exchange chromatography, and both SIgA and IgG fraction were absorbed with goat NS, anti-SIgA, and anti-IgG. IgG fractions absorbed with anti-SIgA or anti-IgG resulted in implantation rates of 0% and 56.8%, respectively, compared to a control of 89.5%. SIgA fractions absorbed with anti-SIgA or anti-IgG resulted in implantation rates of 81.8% and 19.4%. Thus IgG and secretory IgA of the uterine fluids are active in inhibition of fertility.     

Effect of nucleotide cofactor structure on recA protein-promoted DNA pairing. 1. Three-strand exchange reaction.

The structurally related nucleoside triphosphates, adenosine triphosphate (ATP), purine riboside triphosphate (PTP), inosine triphosphate (ITP), and guanosine triphosphate (GTP), are all hydrolyzed by the recA protein with the same turnover number (17.5 min-1). The S0.5 values for these nucleotides increase progressively in the order ATP (45 microM), PTP (100 microM), ITP (300 microM), and GTP (750 microM). PTP, ITP, and GTP are each competitive inhibitors of recA protein-catalyzed ssDNA-dependent ATP hydrolysis, indicating that these nucleotides all compete for the same catalytic site on the recA protein. Despite these similarities, ATP and PTP function as cofactors for the recA protein-promoted three-strand exchange reaction, whereas ITP and GTP are inactive as cofactors. The strand exchange activity of the various nucleotides correlates directly with their ability to support the isomerization of the recA protein to a strand exchange-active conformational state. The mechanistic deficiency of ITP and GTP appears to arise as a consequence of the hydrolysis of these nucleotides to the corresponding nucleoside diphosphates, IDP and GDP. We speculate the nucleoside triphosphates with S0.5 values greater than 100 microM will be intrinsically unable to sustain the strand exchange-active conformational state of the recA protein during ongoing NTP hydrolysis and will therefore be inactive as cofactors for the strand exchange reaction.     

Purification techniques for human interferons

This article outlines the development and general status of present purification methods for human interferons. The isolation of each interferon species from natural sources is extremely difficult because of molecular characteristics, high losses of activity and the small amount of interferon protein present in production media. Few of the highly sophisticated methods meet the requirements for scale-up or give acceptable recoveries for a production process. The adaptation of purification procedures to the different interferon species is described, such as initial concentration, the extraction of beta interferon (IFN-β) by aqueous two-phase systems and the final purification of alpha interferon (IFN-α) and beta interferon to homogeneity. H.p.l.c. techniques are discussed in more detail together with problems in the purification of beta interferon and gamma interferon (IFN-γ). The range of interferon expression and excretion in recombinant microbial and animal cells is reviewed and different approaches for the solubilization and purification of intracellular recombinant interferons are described, which are covered mainly in patent applications.     

Terrestrial ecologists ignore aquatic literature: Asymmetry in citation breadth in ecological publications and implications for generality and progress in ecology

The search for generality in ecology should include assessing the influence of studies done in one system on those done in other systems. Assuming generality is reflected in citation patterns, we analyzed frequencies of terrestrial, marine, and freshwater citations in papers categorized as terrestrial, marine and freshwater in high-impact “general” ecological journals. Citation frequencies were strikingly asymmetric. Aquatic researchers cited terrestrial papers ~ 10 times more often than the reverse, implying uneven cross-fertilization of information between aquatic and terrestrial ecologists. Comparisons between citation frequencies in the early 1980s and the early 2000s for two of the seven journals yielded similar results. Summing across all journals, 60% of all research papers (n = 5824) published in these journals in 2002–2006 were terrestrial vs. 9% freshwater and 8% marine. Since total numbers of terrestrial and aquatic ecologists are more similar than these proportions suggest, the representation of publications by habitat in “general” ecological journals appears disproportional and unrepresentative of the ecological science community at large. Such asymmetries are a concern because (1) aquatic and terrestrial systems can be tightly integrated, (2) pressure for across-system understanding to meet the challenge of climate change is increasing, (3) citation asymmetry implies barriers to among-system flow of understanding, thus (4) impeding scientific and societal progress. Changing this imbalance likely depends on a bottom-up approach originating from the ecological community, through pressure on societies, journals, editors and reviewers.     

Multiple thioredoxin-mediated routes to detoxify hydroperoxides in Mycobacterium tuberculosis

Drug resistance and virulence of Mycobacterium tuberculosis are in part related to the pathogen's antioxidant defense systems. KatG(-) strains are resistant to the first line tuberculostatic isoniazid but need to compensate their catalase deficiency by alternative peroxidase systems to stay virulent. So far, only NADH-driven and AhpD-mediated hydroperoxide reduction by AhpC has been implicated as such virulence-determining mechanism. We here report on two novel pathways which underscore the importance of the thioredoxin system for antioxidant defense in M. tuberculosis: (i) NADPH-driven hydroperoxide reduction by AhpC that is mediated by thioredoxin reductase and thioredoxin C and (ii) hydroperoxide reduction by the atypical peroxiredoxin TPx that equally depends on thioredoxin reductase but can use both, thioredoxin B and C. Kinetic analyses with different hydroperoxides including peroxynitrite qualify the redox cascade comprising thioredoxin reductase, thioredoxin C, and TPx as the most efficient system to protect M. tuberculosis against oxidative and nitrosative stress in situ.     

New synthetic flavonoids as potent protectors against doxorubicin-induced cardiotoxicity.

A series of 3,7-disubstituted-2(3',4'-dihydroxyphenyl) flavones has been studied as potential cardioprotective agents in doxorubicin antitumor therapy. The influence of substituents on the 3 and 7 position of the flavone nucleus on antioxidant activity cytotoxicity and cardioprotective properties was explored to improve the activity of our lead compound 7-monohydroxyethylrutoside. In the protection against Fe(2+)/vitamin C-induced microsomal lipid peroxidation (LPO assay), IC(50) values ranged from 0.2 to 37 microM. In general, the 3-substituted flavones were the most potent compounds in this assay. The cytotoxicity of the new compounds was tested (up to 250 microM) in hepatocytes. LDH leakage ranged from 2.6-29.2%, whereas the GSH concentrations decreased to 87.3-41.3%. Only four compounds out of this series protected the isolated mouse left atrium against doxorubicin-induced toxicity. Because of the positive inotropic effect of 8d (N-(3-(3',4'-dihydroxyflavon-7-yl)oxypropyl)-N,N,N-trimethylammonium chloride) and 10c (3-hydroxyethoxy-7,3',4'-trihydroxyflavone) on the atrium, compounds 9i (3',4'-dihydroxy-3-glucosylflavone) and 10d (N-(3-(7,3',4'-trihydroxyflavon-3-yl)oxypropyl)-N,N,N-trimethylammonium chloride) were selected to be evaluated as cardioprotective agents in vivo.