Using egg yolk in a TRIS-Equex STM paste extender for freezing of dog semen is superior to egg yolk plasma, also after addition of lecithin and catalase.

We compared the results of using egg yolk plasma (EYP) instead of egg yolk (EY) in a TRIS-based Equex STM Paste freezing extender system for dog semen [25]. We also tested whether the addition of lecithin and catalase to the EYP extenders would improve results. Fractionated semen collection was done in 17 stud dogs and the sperm rich fraction diluted with different extenders in 2 steps: (I) TRIS-fructose-citric acid extender (TRIS) containing 20% egg yolk (EY) and 3% glycerol [25], (II) TRIS containing 20% egg yolk plasma (EYP) and 3% glycerol, and (III) TRIS containing 20% EYP and 0.8% lecithin (EYP-L) and 3% glycerol. After equilibration the second dilution step was done: samples with (I) were diluted with TRIS-EY with 7% glycerol and 1% Equex STM paste [25]; samples with (II) and (III) were divided in 2 aliquots each, and one part diluted with TRIS-EYP or TRIS-EYP-L, both containing 7% glycerol and 1% Equex STM paste, and the other one part with the same extenders containing additionally 300 I.U./mL catalase. After freezing and thawing, samples were analyzed by CASA and sperm chromatin structure assay (SCSA); reactive oxygen species (ROS), degree of apoptosis and zona binding ability were determined. Semen samples with TRIS-EY with a final concentration of 5% glycerol and 0.5% Equex STM paste [25] showed best post thaw progressive motility (P), most intact cells, lowest percentage of ROS, acrosome damages, dead and apoptotic cells. Curvilinear velocity (VCL), DNA fragmentation, morphological abnormalities and zona binding ability did not differ between groups. Replacement of egg yolk by EYP increased the ROS and late apoptotic cells. Addition of lecithin and catalase to EYP containing extenders decreased motility and increased complete apoptosis. We conclude that egg yolk is superior to EYP in the here investigated extenders. The TRIS-based extender [25] with EYP could not be improved by addition of lecithin and catalase; however, in-vivo fertilization capacity of the here examined extenders remains to be investigated.

Natural Gums As Viscosity-Enhancers in Pluronic® F-127 Thermogelling Solutions.

Pluronic® F-127 (poloxamer 407) is a versatile pharmaceutical excipient, offering many opportunities for designing novel therapeutic systems. One of its applications is the formation of a thermosensitive solution as a base for concentrated suspensions or emulsions. When such uses are considered, the need for viscosity enhancement emerges, especially when a long-term stability of dispersion is expected. This study covers the evaluation of chosen natural gums (Acacia, Xanthan Gum, Tragacanth and Guar Gum) as viscosity and gelation enhancers for thermosensitive Pluronic F-127 solution. The major poloxamer concentration was 17 % (w/w), and the gum additions were in the range of 0.125 - 0.5 %. Solutions were evaluated by rotational rheometry at fixed temperatures (20, 25 and 37 °C), as well as with continuous temperature increase and decrease. These studies were also supplied by visual inspection during the Tube Inversion Method experiments. Xanthan Gum turned out to be the most effective viscosity enhancer, giving transparent and stable formulations, while Tragacanth gave lesser viscosity enhancement and left the formulations slightly turbid. Acacia significantly inhibited the gelation, and Guar Gum revealed a major incompatibility (precipitation) with poloxamer. Irreversible gelation was not observed in any case.