Publications by authors named "Noriyuki Okuyama"

Purpose: Are human embryos arising from two plus one small pronucleated zygotes, called 2.1 pronuclei (PN), clinically useful?

Methods: In a retrospective embryo cohort study and prospective experimental study, a total of 287 cycles in which at least one 2.1PN was identified in the fertilization check were included.

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Article Synopsis
  • This study introduces a new sperm retrieval technique called micromapping testicular sperm extraction (MMTSE) for treating nonobstructive azoospermia (NOA), aimed at providing a less invasive and more effective approach than traditional microscopic testicular sperm extraction (mTESE).
  • MMTSE involves dividing the testis into four sections and making small needle holes to extract tubules, while allowing for real-time assessment of tissue for sperm presence.
  • Results showed that all 15 patients in the sperm-positive group retrieved sperm successfully, while only 4 out of 25 in the sperm-negative group were successful with mTESE, highlighting MMTSE's potential benefits.
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Purpose: Increasing numbers of women are opting to undergo non-medical oocyte cryopreservation (NMOC). In this report, we present experience at our clinic and discuss NMOC in Japan.

Methods: We followed the progress of 403 women who underwent NMOC at our clinic between 2014 and 2021, totaling 592 reproductive cycles.

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Depolymerization of coal increases the tar yield in coal pyrolysis and enhances the thermoplasticity of the coal, which makes coal more favorable for producing coke and other value-added products like graphite electrodes, carbon fiber, aromatic chemicals, etc. In this study, the authors have proposed a novel coal depolymerization method that combines the oxidation reactions by molecular oxygen and the following reduction reactions by the coexisting gaseous formic acid to upgrade a bituminous coal at 90-150 °C under atmospheric pressure. The softening and melting performance of the treated coals was enhanced when oxygen and formic acid coexisted in gas phase at 90-130 °C.

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A distributed activation energy model (DAEM) was applied to the kinetic analysis of CO and HO gasification reactions for pulverized metallurgical coke. The results of the scanning electron microscopy observations and CO gas adsorption suggested that the gasification reaction occurs at the particle surface. Therefore, a grain model was employed as a gasification reaction model.

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Purpose: To find the best methods to achieve the highest pregnancy and birth rates for couples needing testicular sperm extraction (TESE)-intracytoplasmic sperm injection (ICSI).

Methods: Retrospectively studied were 801 patients with male factor infertility who had undergone TESE-ICSI between April, 1996 and July, 2016 and who had been categorized into four groups: obstructive azoospermia (OA); non-obstructive azoospermia (NOA); Klinefelter syndrome (KS); and cryptozoospermia (Crypt). The sperm retrieval rate, hormone levels, fertilization rate (FR), pregnancy rate (PR), and birth rate (BR) after ICSI among three groups were compared: fresh testicular sperm (FS)-fresh oocytes (FO) (Group I); frozen-thawed testicular sperm-FO (Group II); and FS-vitrified-warmed oocytes (Group III).

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There have been 60 births after transplantation of cryopreserved ovarian tissue: 58 using the slow freezing method, and two using the vitrification method. DMSO and EG are widely used as cryoprotectants. However DMSO is a known epimutagen, and EG has been reported to be toxic in high concentrations.

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