Equine CRISP3 modulates interaction between spermatozoa and polymorphonuclear neutrophils.

Equine spermatozoa induce a uterine inflammatory response characterized by a rapid, transient influx of polymorphonuclear neutrophils (PMNs). Seminal plasma proteins have been shown to modulate the interaction between spermatozoa and PMNs, but a specific protein responsible for this function has not been identified. The objective of this study was to isolate and identify a protein in equine seminal plasma that suppresses binding between spermatozoa and PMNs. Seminal plasma was pooled from five stallions, and proteins were precipitated in 60% (w/v) ammonium sulfate and dialyzed (3500 MW cutoff). Proteins were submitted to a Sephacryl S200 column, and fractions were pooled based on the fraction pattern. Each pool was analyzed for protein concentration and tested for its suppressive effect on PMN/sperm binding. Protein pools with biological activity were submitted to ion-exchange chromatography (diethylaminoethyl [DEAE] Sephadex column) with equilibration buffers containing 0.1-0.5M NaCl. Eluants were pooled, analyzed for protein concentration, and tested for suppressive effects on PMN/sperm binding. Protein distribution and purity were determined by one- and two-dimensional SDS-PAGE, and the purified protein was submitted for sequence analysis and identification. This protein was identified as equine CRISP3 and was confirmed by Western blotting. Suppression of PMN/sperm binding by CRISP3 and seminal plasma was confirmed by flow cytometry (22.08% ± 3.05% vs. 2.06% ± 2.02% vs. 63.09% ± 8.67 for equine seminal plasma, CRISP3, and media, respectively; P < 0.0001). It was concluded that CRISP3 in seminal plasma suppresses PMNs/sperm binding, suggesting that CRISP3 regulates sperm elimination from the female reproductive tract.

In situ DMSO hydration measurements of HTS compound libraries.

Compounds used in high throughput screening (HTS) are typically dissolved in DMSO. These solutions are stored automation-friendly racks of wells or tubes. DMSO is hygroscopic and quickly absorbs water from the atmosphere. When present in DMSO compound solutions, water can accelerate degradation and precipitation. Understanding DMSO hydration in an HTS compound library can improve storage and screening methods by managing the impact of water on compound stability. A non-destructive, acoustic method compatible with HTS has been developed to measure water content in DMSO solutions. Performance of this acoustic method was compared with an optical technique and found to be in good agreement. The accuracy and precision of acoustic measurements was shown to be under 3% over the tested range of DMSO solutions (0% to 35% water by volume) and insensitive to the presence of HTS compounds at typical storage concentrations. Time course studies of hydration for wells in 384-well and 1536-well microplates were performed. Well geometry, fluid volume, well position and atmospheric conditions were all factors in hydration rate. High rates of hydration were seen in lower-volume fills, higher-density multi-well plates and when there was a large differential between the humidity of the lab and the water content of the DMSO. For example, a 1536-well microplate filled with 2microL of 100% DMSO exposed for one hour to a laboratory environment with approximately 40% relative humidity will absorb over 6% water by volume. Understanding DMSO hydration rates as well as the ability to reverse library hydration are important steps towards managing stability and availability of compound libraries.

Titration calorimetry study of an anti-idiotypic antibody cascade in a human melanoma-associated antigen system.

The thermodynamic parameters of interactions between six variants of the anti-idiotypic monoclonal antibody (mAb) CGP 60686 produced by the hybridoma MK2-23 with an idiotypic mAb and five different anti-anti-idiotypic mAb were studied with high sensitivity titration calorimetry. CGP 60686 recognizes an epitope in the antigen-combining region of the human high-molecular-weight-melanoma-associated antigen (HMW-MAA)-specific mouse mAb CGP 76873 produced by the hybridoma 763.74. The five HMW-MAA-specific anti-anti-idiotypic mAbs GH 464, GH 518, GH 149, GH 386 and GH 586 were generated from mice immunization with mAb CGP 60686. All interactions between the anti-idiotypic mAb and the idiotypic mAb or the anti-anti-idiotypic mAb showed large exothermic binding enthalpies between -15 and -23 kcal/mol and binding affinities larger than 6 x 10(9) M-1. Four of the five anti-anti-idiotypic mAbs tested exhibited significantly higher binding enthalpies for the interaction with the anti-idiotypic than the idiotypic mAbs. Replacement of either the heavy or the light chain variable region of the anti-idiotypic mAbs with an unrelated variable region abolished the idiotype to anti-idiotype interaction. Thus, both the heavy and the light chain variable region of the anti-idiotypic mAbs are required for binding to the idiotype. The values of the binding enthalpy showed only small variations when binding of the idiotypic mAb CGP 76873 to four variants of the anti-idiotypic mAb CGP 60686 with different immunoglobulin constant regions, but identical variable regions were compared. Furthermore, Fab fragments of the idiotypic mAbs showed almost the same binding enthalpy per binding site as the whole IgG molecules. Immunoglobulin constant regions thus had little influence on the idiotype to anti-idiotype interactions. Taken together, the observed thermodynamic parameters suggest that the idiotype to anti-idiotype interactions studied here are enthalpy-driven processes with only minor entropic contributions. High sensitivity titration calorimetry was used to monitor protein-protein interactions within an anti-idiotypic antibody cascade. It was found that the direct measurement of the interaction enthalpy allowed a quantitative characterization of the binding processes studied.

Prognostic value of baseline absolute lymphocyte concentration and neutrophil/lymphocyte ratio in dogs with newly diagnosed multi-centric lymphoma.

Canine multi-centric B-cell lymphoma shares similarities with diffuse large B-cell (Non-Hodgkin's) lymphoma (NHL) in people. In people with NHL, lymphopenia at diagnosis and first relapse and neutrophil/lymphocyte ratio (N:L) > 3.5 are negative prognostic factors for survival. The objective of this study was to determine if lymphocyte concentration at diagnosis and first relapse and N:L were prognostic for survival in dogs with newly diagnosed multi-centric lymphoma. Medical records of 77 dogs with multi-centric lymphoma treated with a CHOP-based chemotherapy protocol were retrospectively evaluated. Absolute lymphocyte concentration and N:L ratio at presentation of dogs pre-treated with steroids was not significantly different from dogs who had not received steroids. On multivariate analysis, only immunophenotype remained significant for progression-free survival (PFS), whereas no variables remained significant for ST. A prospective study of these haematologic variables is warranted to assess their true significance.

Stereoselection in designed three-helix bundle metalloproteins.

The stereochemical consequences of the metal-ion assisted self-assembly of parallel three-helix peptide bundles are investigated. Chiral induction in the self-assembly of systems containing extensive protein secondary structure is compared with the racemic synthesis of short metallopeptides. Isolation and characterization of the individual stereoisomers of an exchange-inert metalloprotein provide structural insights into analogous exchange-labile systems.

Conformational dependence of electron transfer across de novo designed metalloproteins.

Flash photolysis and pulse radiolysis measurements demonstrate a conformational dependence of electron transfer rates across a 16-mer helical bundle (three-helix metalloprotein) modified with a capping CoIII(bipyridine)3 electron acceptor at the N terminus and a 1-ethyl-1'-ethyl-4,4'- bipyridinium donor at the C terminus. For the CoIII(peptide)3-1-ethyl-1'-ethyl-4,4'-bipyridinium maquettes, the observed transfer is a first order, intramolecular process, independent of peptide concentration or laser pulse energy. In the presence of 6 M urea, the random coil bundle (approximately 0% helicity) has an observed electron transfer rate constant of kobs = 900 +/- 100 s-1. In the presence of 25% trifluoroethanol (TFE), the helicity of the peptide is 80% and the kobs increases to 2000 +/- 200 s-1. Moreover, the increase in the rate constant in TFE is consistent with the observed decrease in donor-acceptor distance in this solvent. Such bifunctional systems provide a class of molecules for testing the effects of conformation on electron transfer in proteins and peptides.

Rhoptry-associated protein 1-binding monoclonal antibody raised against a heterologous peptide sequence inhibits Plasmodium falciparum growth in vitro.

Monoclonal antibodies (MAbs) specific for Plasmodium falciparum rhoptry-associated protein 1 (RAP-1) were generated and tested for inhibition of parasite growth in vitro. The majority of indirect immunofluorescence assay (IFA)-positive MAbs raised against recombinant RAP-1 positions 23 to 711 (rRAP-1(23-711)) recognized epitopes located in the immunodominant N-terminal third of RAP-1. MAbs specific for the building block 35.1 of the synthetic peptide malaria vaccine SPf66 also yielded an IFA staining pattern characteristic for rhoptry-associated proteins and reacted specifically with rRAP-1 and parasite-derived RAP-1 molecules p67 and p82. Cross-reactivity with RAP-1 was blocked by the 35.1 peptide. Epitope mapping with truncated rRAP-1 molecules and overlapping peptides identified the linear RAP-1 sequence Y218KYSL222 as a target of the anti-35.1 MAbs. This sequence lacks primary sequence similarity with the 35.1 peptide (YGGPANKKNAG). Cross-reactivity of the anti-35.1 MAbs thus appears to be associated with conformational rather than sequence homology. While the anti-35.1 MAb SP8.18 exhibited parasite growth-inhibitory activity, none of the tested anti-rRAP-1(23-711) MAbs inhibited parasite growth, independently of their fine specificity for the RAP-1 sequences at positions 33 to 42, 213 to 222, 243 to 247, 280 to 287, or 405 to 446. The growth-inhibitory activity of MAb SP8.18 was, however, accelerated by noninhibitory anti-RAP-1 MAbs. Results demonstrate that in addition to fine specificity, other binding parameters are also crucial for the inhibitory potential of an antibody.