BACKGROUND
Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis and represent a crucial resource for male fertility restoration. It has not been well documented, however, whether ...the recovery of SSC population size after cytotoxic damage associates with the kinetics of male fertility restoration. We addressed this issue using the mouse as a model.
METHODS
Following single injections of busulfan at 15, 30 or 45 mg/kg into male mice, we examined their ability to sire offspring at different times by natural mating and determined SSC numbers using spermatogonial transplantation. We measured testis physiological parameters (testis weights, sperm counts, serum and intratesticular testosterone levels, and histological assessments of spermatogenic recovery) and quantified the expression of glial-cell-line-derived neurotrophic factor (GDNF) transcripts.
RESULTS
Regardless of busulfan doses, fertility was lost within 4 weeks after treatment, while more than 95% of SSCs were lost within 3 days. Fertility and SSC numbers gradually recovered with time, but the recoveries were delayed at higher busulfan doses. Interestingly, SSC numbers reached ∼30% of before-treatment levels by 4 weeks prior to the time of fertility restoration, across the dose groups. Sperm counts were ∼20% of before-treatment levels at the onset of fertility restoration, regardless of busulfan doses. We detected a significant increase in total GDNF mRNA per testis immediately after busulfan treatment.
CONCLUSIONS
The loss and restoration of fertility after busulfan treatment are direct consequences of SSC loss and expansion. Our data suggest that there is a threshold in SSC numbers that allows for male fertility restoration and that the testicular somatic environment responds rapidly and temporarily to the loss of spermatogonia, including SSCs, by altering GDNF mRNA levels. This study provides fundamental information to clinically apply SSCs for male fertility restoration in the future.
This study proposes a method for analyzing magnetic devices such as inductors and wireless power transfer (WPT) systems based on a Cauer equivalent circuit. The circuit parameters are determined ...based on computed or measured input impedance. It is possible to obtain a dynamic response and eddy-current loss in the time domain for arbitrary drive voltage waveforms from the synthesized Cauer equivalent circuit. Magnetic saturation in the core of an inductor could be accurately represented using the Cauer circuit. Moreover, the transient response of a WPT device is shown to be modeled by the Cauer circuit, including the effect of misalignment.
Ultracold neutrons (UCNs) can be bound by the potential of terrestrial gravity and a reflecting mirror. The wave function of the bound state has characteristic modulations. We carried out an ...experiment to observe the vertical distribution of the UCNs above such a mirror at the Institut Laue-Langevin in 2011. The observed modulation is in good agreement with that prediction by quantum mechanics using the Wigner function. The spatial resolution of the detector system is estimated to be 0.7 μm. This is the first observation of gravitationally bound states of UCNs with submicron spatial resolution.
In this study we investigated the effect of astaxanthin (Ax), which exhibits strong antioxidant activity, during invitro growth (IVG) on the developmental competence of oocytes and steroidogenesis of ...granulosa cells derived from early antral follicles. Bovine oocyte-cumulus-granulosa complexes collected from early antral follicles were cultured for 12 days in the presence or absence (control) of 500µM Ax. The viability of oocytes and antrum formation in the granulosa cell layer during IVG culture were greater in the presence than absence of Ax (P<0.05). Regardless of Ax treatment, 17β-oestradiol production increased during IVG culture; however, progesterone production was significantly lower in the presence than absence of Ax (P<0.05). Reactive oxygen species levels were lower in Ax-treated oocytes than in controls after IVG (P<0.05). Although nuclear maturation and cleavage rates did not differ between the Ax-treated and control groups, Ax treatment led to weaker cathepsin B activity in oocytes and better blastocyst rates than in controls (P<0.05). Accordingly, Ax treatment during IVG increased the total number of cells in blastocysts (P<0.05). These results indicate that Ax supplementation of IVG medium improves the quality of bovine oocytes due to its antioxidative effects on growing oocytes and its suppression of the luteinisation of granulosa cells.
In competitive markets, such as electronic commerce, evaluations of base-level performance and benchmarking are fundamental for retailers focusing efforts. Hence, we propose a new and practical ...approach to measuring retailers' relative performance and benchmarking through a unique index that integrates digital, physical, and financial factors. We investigated 13 traditional retailers controlling 36 marketplaces (i.e., online platforms) in Brazil in 2020. The traffic to the marketplace, the companies' inventory, capital intensity (physical infrastructure), and gross margin were used in the slacks-based measure and data envelopment analysis (DEA) model, followed by a slacks-based measure super-efficiency model for the sensitivity analysis. Companies' relative performance is then determined, as well as thei customized targets for achieving efficiency. Three types of marketplaces are explored: pure (direct sales from suppliers to consumers for a fee), reselling (products purchased from suppliers and resold), and hybrid (both options direct and resale, depending on the product). Although data envelopment analysis has already been applied to examine retailers' performance, there are few extant applications to e-commerce. Our findings show that retailers who operate through specialized (normally reselling) marketplaces tend to be inefficient, and retailers prefer to manage one non-specialized (normally hybrid) marketplace and focus efforts on achieving efficiency instead of managing many marketplaces inefficiently.
Formation of Frank-type faults on the basal plane in 4H-SiC{0
0
0
1} epitaxial growth has been investigated by grazing incidence synchrotron reflection X-ray topography and transmission electron ...microscopy. The Frank faults, which are formed by conversion of a 1
c threading screw dislocation (TSD) in the substrate as well as simultaneous generation of a 1
c TSD during epitaxial growth, are confirmed to be created by four Frank partials with a Burgers vector of 1/40
0
0
1 type having the same sign on four different basal planes. The fine features of the X-ray topography contrast are confirmed to reflect the microscopic structure of the Frank faults. A variety of Frank fault formation has been revealed by comparing topography images taken before and after epitaxial growth. The formation mechanism of the Frank faults is discussed based on the evaluated microscopic structures.
Formation of extended defects during 4H-SiC{0
0
0
1} epitaxial growth has been investigated by grazing incidence synchrotron reflection X-ray topography and KOH-defect selective etching analysis. ...Details of the defect topography contrast features are collated with the KOH etched features. Conversion of threading screw dislocations (TSDs) into a defect on the basal plane as well as a carrot defect is tracked by performing topography before and after epitaxial growth. We found simultaneous nucleation of a TSD and a defect on the basal plane during epitaxial growth. The polytype inclusions are confirmed to be transparent in the topography condition. Formation of threading dislocation clusters during epitaxial growth is also investigated.
The air fluorescence technique is used to detect ultrahigh-energy cosmic rays (UHECR), and to estimate their energy. Of fundamental importance is the photon yield due to excitation by electrons, in ...air of various densities and temperatures. After our previous report, the experiment has been continued using a 90Sr β source to study the pressure dependence of photon yields for radiation in nitrogen and dry air. The photon yields in 15 wave bands between 300nm and 430nm have been determined. The total photon yield between 300nm and 406nm (used in most experiments) in air excited by a 0.85MeV electron is 3.81±0.13 (±13% systematics) photons per meter at 1013hPa and 20°C. The air density and temperature dependencies of 15 wave bands are given for application to UHECR observations.
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