Avaliação de diferentes crioprotetores intra e extracelulares na criopreservação de sêmen de touros / Evaluation of different intra and extracellular cryoprotectants on bull semen cryopreservation

Em um delineamento experimental usando o fatorial 3x2, três crioprotetores internos, glicerol (GLI), etilenoglicol (EG) e dimetilformamida (DMF), e dois externos, gema de ovo (GEMA) e lipoproteína de baixa densidade (LDL), avaliaram-se a motilidade ao descongelamento de GLI-GEMA 53,9±1,96, sendo superior aos demais tratamentos (P<0,05). Na avaliação de morfologia ao descongelamento, não houve diferença (P>0,05) entre os tratamentos EG-GEMA 68,3±1,58, EG-LDL 72,2±2,39 e DMF-GEMA 68,7±1,67 que foram mais altos que os demais (P<0,05). A avaliação de integridade de membrana por fluorescência ao descongelamento GLI-GEMA 34,2±2,28 e EG-GEMA 30,9±1,32 não diferiram entre si (P>0,05), mas foram mais elevados que os demais (P<0,05), enquanto que a HOST dos tratamentos DMF-GEMA 13,6±1,30 e DMF-LDL 9,8±0,78 diferirem entre si (P<0,05) e foram mais baixas que as demais (P<0,05). O uso de etilenoglicol associado à gema de ovo pode ser uma alternativa ao uso de glicerol nos protocolos de congelamento de sêmen de touros.

The experiment was designed as 3 x 2 factorial design, with three internal cryoprotectants, glycerol (GLY), etileneglycol (EG) and dymethilformamide (DMF) and two external, egg yolk (YOLK) and density low lipoproteina (LDL). The motility at thawing for GLY-YOLK (53.9±1.96) was higher than other treatments (P<0.05). The percentage of cells with normal morphology at thawing was not different between EG-YOLK (68.3±1.58), EG-LDL (72.2±2.39) and DMF-YOLK (68.7±1.67), but they were higher than the others (P<0.05). The evaluation of membrane integrity through fluorescent probes at thawing indicate that GLY-YOLK (34.2±2.28) and EG-YOLK (30.9±1.32) were not different (P>0.05), but were higher than the others (P<0.05). The evaluation of membrane integrity through hypoosmotic swelling test (HOST) indicate that DMF-YOLK (13.6±1.30) and DMF-LDL (9.8±0.78) were different (P<0.05) and lower than the others (P<0.05). The use of ethylene glycol associated to egg yolk can be a viable alternative to the use of glycerol in bull semen freezing protocols.

Effect of recombinant bovine somatotropin on plasma concentrations of insulin-like growth factor I, insulin and membrane integrity of bull spermatozoa.

This study aimed to evaluate the effect of the exogenous recombinant bovine somatotropin (rbST) on plasma concentrations of insulin-like growth factor I (IGF-I), insulin and semen quality of bulls. Twenty bulls (Aberdeen Angus and Brangus) were divided by breed into two groups. Placebo group was injected with NaCl 0.9% (s.c.) and treatment group with rbST (s.c., 500 mg) at days 0 and 14 of the experiment. Immediately after semen collection, blood samples were taken on days 0, 14, 28, 42 and 56 of the experiment. Semen was also collected on day 70 of the experiment. Evaluation of sperm motility was performed at pre-freezing and post-thawing stage, whereas assessment of sperm membrane integrity was performed after freezing and thawing. Analysis of data revealed that the effect of treatment and treatment-by-collection day on plasma concentrations of IGF-I and insulin was not significant. However, mean plasma concentrations of IGF-I and insulin were affected (p < 0.0001) by days of blood sampling. Effect of treatment and treatment-by-collection day on motility of spermatozoa was similar (p > 0.05) at pre-freezing and post-thawing stage. Intactness of plasmalemma and tail membrane of spermatozoa at post-thawing stage was higher (p < 0.05) in rbST-treated group than in control. In conclusion, rbST did not affect plasma concentrations of IGF-I and insulin, however, it did improve post-thaw sperm membrane integrity.

Clinical effects of a stannous fluoride mouthrinse on plaque.

The purpose of this 3-week, double-blind study was to determine the effect of a stannous fluoride-containing mouthrinse on existing and developing dental plaque. A total of 55 subjects (mean age = 31.42 yrs.) received a professional prophylaxis in randomly assigned contralateral quadrants and were then stratified into two balanced groups based on screening plaque scores: one group (27 subjects) used the placebo rinse, the second group (28 subjects) used the test mouthrinse (0.63% diluted to 0.1% stannous fluoride). Plaque index (PI) and stain index (SI) were scored at baseline, week 1 and week 3. Gingival inflammation (GI) was monitored as a measure of product irritancy potential. The PI for the stannous fluoride rinse was significantly lower than the placebo, (p < 0.0001), for both prophied and unprophied sites with an average reduction of 29% at week 1 and 28% at week 3. There was no statistically significant difference between the presence or absence of prophylaxis. Plaque indexes for both stannous fluoride and placebo showed significant reduction (p < 0.0001) compared to baseline in all sites. Differences in staining potential between stannous fluoride and placebo were not significant (p > 0.05) at any time during the study. The stain index for both stannous fluoride and placebo showed a non-significant increase from baseline in the prophied and unprophied sites. No irritancy was noted, although a trend towards lower GI scores was observed at 3 weeks for the stannous fluoride group.(ABSTRACT TRUNCATED AT 250 WORDS)

Right-shift processes.

We present a class of Markov processes with multidimensional finite state space on which the infinitesimal transition movement is a shifting of one unit from one coordinate to some other to its right. We show how to represent the Kolmogorov forward equations as a triangular system.