The use of IVF and intracytoplasmic sperm injection (ICSI) to treat male infertility due to severe asthenozoospermia in cases of electron microscopically confirmed axonemal abnormalities has been reported. However, even with these sophisticated technologies, very few pregnancies and births have been achieved with ejaculated spermatozoa in infertility due to this condition. The existence of sperm-derived defects preclude normal embryo development, and another reason for low success rates may be that the most commonly used method for selecting viable spermatozoa for ICSI is sperm motility, which is absent in affected men. Consequently, the likelihood of selecting non-viable spermatozoa for ICSI is higher in these cases. This report describes a case of a pregnancy achieved by ICSI with ejaculated spermatozoa containing 93% non-specific axonemal alterations and 90% abnormal or absent mitochondrial sheaths. A total of 14 oocytes was obtained from the 31-year-old patient in her first IVF treatment cycle. Three of the 13 matured (metaphase II) oocytes were inseminated conventionally, and the other 10 metaphase II oocytes were submitted to ICSI. None of the oocytes inseminated conventionally were fertilized. Of the 10 oocytes submitted to ICSI, four zygotes and cleavage embryos resulted. Three embryos were transferred on day 3, and a successful pregnancy was achieved. One gestational sac, together with regular heart activity, was recorded by ultrasonography at 8 weeks of gestation. A pregnancy is currently ongoing.
The effect of beta-adrenergic stimulation on tetanic tension (TT), maximal rate of rise of tension (+TT) and phospholamban (PHL) phosphorylation were studied in the perfused rat heart. 3 x 10(-8) M isoproterenol perfused at different [Ca2+]o 0.25, 1.35 and 3.85 mM, significantly decreased TT while increased +TT and PHL phosphorylation at the three [Ca2+]o studied. Regression lines of the relationship between +TT and TT from individual data obtained at each [Ca2+]o in the presence and in the absence of isoproterenol, show that for the same level of +TT, TT is lower in the presence of isoproterenol, i.e. at high levels of PHL phosphorylation. The slopes of the lines were 0.137 s and 0.427 s (P less than 0.05) in the presence and absence of isoproterenol respectively. The decrease in TT produced by the beta-agonist can be attributed to its relaxant action prevailing over its inotropic effect and may represent the mechanical expression of the enhanced phosphorylation of phospholamban.
The aim of the present study was to elucidate the conditions required to obtain tetanic contractions in rat intact heart and to investigate whether tetanic tension was actually the maximal tension that isolated rat heart is able to generate. Experiments were performed on isolated rat hearts (Langendorff technique) perfused at constant coronary flow (8-9 ml/min). Rapid repetitive stimulation (400 to 3000 pulses/min) failed to elicit a fused tetanus. The first twitch that occurred at the end of the rapid stimulation period was a potentiated beat (PSP) of significantly greater magnitude than that of the regular twitch. This potentiation declined in successive beats. When rapid electrical stimulation (600 to 3000 pulses/min) was applied to hearts treated with 5 x 10(-6) M ryanodine, the result was a fused and steady tetanic tension. Ryanodine suppressed PSP. Tetanic tension could be graded by stepwise increase of [Ca2+]o from 0.25 to 5 mM. Maximal tetanic tension occurred at a [Ca2+]o between 3.85 and 5 mM. At any of the [Ca2+]o, tetanic tension was significantly greater than the tension of the twitch obtained at approximately the natural frequency of rat heart in the intact animal (250 beats/min) but it did not differ significantly from the twitch obtained at 100 beats/min. Moreover, the tension of PSP at 0.25 and 1.35 mM [Ca2+]o was significantly greater than the maximal tetanic tension that could be obtained. Similar results to that obtained with ryanodine, were obtained in additional experiments in which caffeine was used to evoke tetanic contraction.(ABSTRACT TRUNCATED AT 250 WORDS)
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