A Convenient and Effective Preoxygenation Technique for Prolonging Deep Inspiration Breath-Hold Duration With a Venturi Mask With a 50% Oxygen Concentration.

PURPOSE: Voluntary deep inspiration breath-hold (DIBH) is commonly used in radiation therapy (RT), but the short duration of a single breath-hold, estimated to be around 20 to 40 seconds, is a limitation. This prospective study aimed to assess the feasibility and safety of using a simple preoxygenation technique with a Venturi mask to prolong voluntary DIBH. METHODS AND MATERIALS: The study included 33 healthy volunteers and 21 RT patients. Preoxygenation was performed using a Venturi mask with a 50% oxygen concentration. Paired t tests compared the duration of a single DIBH in room air and after 5, 15, and 30 minutes of preoxygenation in healthy volunteers. Sustainability of breath-hold and tolerability of heart rate and blood pressure were assessed for multiple DIBH durations in both volunteers and patients. RESULTS: In healthy volunteers, a 15-minute preoxygenation significantly prolonged the duration of a single DIBH by 24.95 seconds compared with 5-minute preoxygenation (89 ± 27.76 vs 113.95 ± 30.63 seconds; P < .001); although there was a statistically significant increase in DIBH duration after 30-minute preoxygenation, it was only extended by 4.95 seconds compared with 15-minute preoxygenation (113.95 ± 30.63 vs 118.9 ± 29.77 seconds; P < .01). After 15-minute preoxygenation, a single DIBH lasted over 100 seconds in healthy volunteers and over 80 seconds in RT patients, with no significant differences among 6 consecutive cycles of DIBH. Furthermore, there were no significant differences in heart rate or blood pressure after DIBHs, including DIBH in room air and 6 consecutive DIBHs after 15-minute preoxygenation (all P > .05). CONCLUSIONS: Preoxygenation with a 50% oxygen concentration for 15 minutes effectively prolongs the duration of 6 cycles of DIBH both in healthy volunteers and RT patients. The utilization of a Venturi mask to deliver 50% oxygen concentration provides a solution characterized by its convenience, good tolerability, and effectiveness.

Gold-Catalyzed Oxidations of 1,3-Diynamides with C(1) versus C(3) Regioselectivity: Catalyst-Dependent Oxidative Cyclizations in the C(3) Oxidation.

This work reports two distinct paths in catalytic oxidations of 1,3-diynamides with 8-methylquinoline oxide. A typical C(1) regioselectivity was observed for aryl-substituted 1,3-diyn-1-amides, whereas an unexpected C(3) regioselectivty occurred for 5-hydroxy1,3-diyn-1-amides. We focused on the C(3) oxidations of 5-hydroxy1,3-diyn-1-amides because we observed two oxidative cyclizations of the same substrates to yield 2-aminomethylenefuran-3(2H)-ones and 2-amino-4H-pyran-4-ones using AuCl3 and a cationic gold catalyst, respectively. Density functional theory calculations were performed to rationalize the C(3) regioselectivity on 5-hydroxy1,3-diyn-1-amides.

The Replacement of Monosaccharide by Mannitol or Sorbitol in the Freezing Extender Enhances Cryosurvival of Ram Spermatozoa.

In this study, the protective effects of monosaccharides (glucose and fructose) and sugar alcohols (mannitol, sorbitol, and xylitol) on frozen ram spermatozoa were evaluated and compared. The motility, moving velocity, and hypoosmotic swelling capability of spermatozoa frozen with monosaccharide or sugar alcohol were measured using a computer-assisted spermatozoa analyzer system. The acrosome status, membrane integrity, distribution of phosphatidylserine (PS), and mitochondrial membrane potential (MMP) were analyzed using fluorescence staining and flow cytometry. The results indicated that similar to glucose or fructose, the presence of sugar alcohol in the freezing extender cannot significantly improve the motility and moving velocity of ram spermatozoa equilibrated at 5°C. In terms of motility, pathway velocity, curve velocity, hypoosmotic swelling capability, acrosome and membrane integrity, and MMP, the inclusion of mannitol or sorbitol in the extender can significantly improve the quality of frozen-thawed ram spermatozoa compared to glucose or fructose. However, the effects of mannitol or sorbitol on linear velocity and PS distribution of frozen-thawed spermatozoa were similar to those of the monosaccharides (p > 0.05). In addition, the ability of xylitol to protect acrosome and maintain MMP in frozen-thawed spermatozoa was significantly higher compared with glucose or fructose (p < 0.05), although it could not improve the other evaluated parameters. Finally, there is no significant difference existing between mannitol and sorbitol with respect to the above evaluated parameters. In conclusion, the replacement of glucose or fructose by mannitol or sorbitol in a freezing extender can improve the postthaw quality of ram spermatozoa under specific freezing conditions. Moreover, the protective effects of mannitol and sorbitol on frozen-thawed ram spermatozoa are superior to that of xylitol. However, in the presence of sugar alcohols, the cryoinjury on spermatozoa membrane is still serious. In the future, the question of protecting the membrane of frozen-thawed spermatozoa needs further research.

Cryotop vitrification of porcine parthenogenetic embryos at the early developmental stages.

The objective of this study was to evaluate the effects of early developmental stages at which Cryotop vitrification is performed on subsequent survival and in vitro development of porcine parthenogenetic activation embryos. The zygotes that were cultured for 4, 8, and 18 hours post electric activation (h.p.a.) and two- and four-cell embryos were vitrified, warmed, and continuously cultured for the remaining period. The zygotes vitrified at 4, 8, and 18 h.p.a. showed similar percentages of survival, cleavage, and blastocyst formation. No difference in viability was observed after vitrification of two- and four-cell embryos, but the embryos vitrified at the two-cell stage exhibited significantly higher blastocyst formation rate than those vitrified at the four-cell stage. However, vitrifying embryos resulted in significantly decreased survival and development rates, regardless of the developmental stage of the embryos. In addition, the final developmental stage, diameter, apoptotic index, and the number of inner cell mass, trophectoderm, and total cells of blastocysts derived from embryos vitrified at any stage of the early culture were similar to those of fresh blastocysts. In conclusion, our data indicate that the early-stage porcine parthenogenetically activated embryos including the zygote, two cells, and four cells have a high ability to survive cryopreservation; these viable embryos after vitrification can produce respectable development rates and good-quality blastocysts.