Proposition of an outflow boundary approach for carotid artery stenosis CFD simulation

The purpose of this study was to propose an innovative approach of setting outlet boundary conditions for the computational fluid dynamics (CFD) simulation of human common carotid arteries (CCAs) bifurcation based on the concept of energy loss minimisation at flow bifurcation. Comparisons between this new approach and previously reported boundary conditions were also made. The results showed that CFD simulation based on the proposed boundary conditions gave an accurate prediction of the critical stenosis ratio of carotid arteries (at around 65%). Other boundary conditions, such as the constant external pressure (P = 0) and constant outflow ratio, either overestimated or underestimated the critical stenosis ratio of carotid arteries. The patient-specific simulation results furthermore indicated that the calculated internal carotid artery flow ratio at CCA bifurcation (61%) coincided with the result obtained by clinical measurements through the use of Colour Doppler ultrasound.     

Optical coherence tomography for dynamic investigation of mammalian reproductive processes

The biological events associated with mammalian reproductive processes are highly dynamic and tightly regulated by molecular, genetic, and biomechanical factors. Implementation of live imaging in reproductive research is vital for the advancement of our understanding of normal reproductive physiology and for improving the management of reproductive disorders. Optical coherence tomography (OCT) is emerging as a promising tool for dynamic volumetric imaging of various reproductive processes in mice and other animal models. In this review, we summarize recent studies employing OCT-based approaches toward the investigation of reproductive processes in both, males and females. We describe how OCT can be applied to study structural features of the male reproductive system and sperm transport through the male reproductive tract. We review OCT applications for in vitro and dynamic in vivo imaging of the female reproductive system, staging and tracking of oocytes and embryos, and investigations of the oocyte/embryo transport through the oviduct. We describe how the functional OCT approach can be applied to the analysis of cilia dynamics within the male and female reproductive systems. We also discuss the areas of research, where OCT could find potential applications to progress our understanding of normal reproductive physiology and reproductive disorders.     

Low-temperature culturing improves survival rate of tissue-engineered cardiac cell sheets

Assembling three-dimensional (3D) tissues from single cells necessitates the use of various advanced technological methods because higher-density tissues require numerous complex capillary structures to supply sufficient oxygen and nutrients. Accordingly, creating healthy culture conditions to support 3D cardiac tissues requires an appropriate balance between the supplied nutrients and cell metabolism. The objective of this study was to develop a simple and efficient method for low-temperature cultivation (< 37 °C) that decreases cell metabolism for facilitating the buildup of 3D cardiac tissues. We created 3D cardiac tissues using cell sheet technology and analyzed the viability of the cardiac cells in low-temperature environments. To determine a method that would allow thicker 3D tissues to survive, we investigated the cardiac tissue viability under low-temperature culture processes at 20–33.5 °C and compared it with the viability under the standard culture process at 37 °C. Our results indicated that the standard culture process at 37 °C was unable to support higher-density myocardial tissue; however, low-temperature culture conditions maintained dense myocardial tissue and prevascularization. To investigate the efficiency of transplantation, layered cell sheets produced by the low-temperature culture process were also transplanted under the skin of nude rats. Cardiac tissue cultured at 30 °C developed denser prevascular networks than the tissue cultured at the standard temperature. Our novel findings indicate that the low-temperature process is effective for fabricating 3D tissues from high-functioning cells such as heart cells. This method should make major contributions to future clinical applications and to the field of organ engineering.     

Variation with age in the numbers of ovulated ova and follicles of Wistar-Imamichi adult rats superovulated with eCG-hCG.

There are large variations with age in the number of ovulated ova found in superovulated female Wistar-Imamichi rats. In this study we investigated the numbers of ovulated ova and follicles with the aim of developing a superovulation technique that minimises variations. We also examined the number of non-atretic follicles in untreated rats aged 7-14 weeks, for each week of age. The numbers of 250-549 microm non-atretic follicles in untreated rats and the numbers of ovulated ova in superovulated rats both reached a peak at 12 weeks of age. The coefficients of variation for both follicle numbers and ova numbers changed with each week of age, reaching a maximum at 9 weeks of age and a minimum at 12 weeks of age. In order to achieve stable numbers of ova from superovulated rats, satisfactory results will be achieved using 12-week-old rats, minimising individual variations, with high numbers of ova.     

Development of an animal model of late asthmatic response in guinea pigs and effects of anti-asthmatic drugs.

We developed an animal model of late asthmatic response (LAR) in guinea pigs and examined the effects of anti-asthmatic drugs and peptide leukotriene antagonist, MCI-826, on this model. Bronchial challenge of DNP-As (Dinitrophenylated-Ascaris suum extract)-sensitized guinea pigs induced a biphasic increase in pulmonary resistance (RL) with the maximal increase being observed immediately (IAR, immediate asthmatic response) and 3 to 5 hr after antigen inhalation (LAR). Twelve of 22 guinea pigs showed both IAR and LAR. The average increases in RL for all 22 guinea pigs at IAR and LAR, were 168 +/- 13 and 207 +/- 16 (% of baseline value), respectively. Bronchoalveolar lavage (BAL) fluid of guinea pigs that received antigen, revealed increases in the numbers of eosinophils (7.3-fold compared to animals receiving saline) and neutrophils (5.3-fold compared to animals receiving saline) 4 hr after antigen inhalation. When DSCG (disodium cromoglycate) was administered (10 mg/kg, i.v.) before antigen challenge, DSCG significantly inhibited IAR (p less than 0.05) and slightly inhibited LAR (p less than 0.2). Theophylline (30 mg/kg, p.o.) administered before antigen, slightly inhibited both IAR and LAR (p less than 0.2). Salbutamol (3 mg/kg, i.p.) administered before antigen, significantly inhibited IAR (p less than 0.05), but did not affect LAR. These results were correlated with clinical trials. Moreover, peptide leukotriene antagonist, MCI-826, (E)-2,2-Diethyl-3'-[2-[2-(4- isopropyl)thiazolyl] ethenyl]succinanilic acid (0.1 mg/kg, p.o.) administered 1 hr before antigen challenge, significantly inhibited both IAR and LAR (p less than 0.05). MCI-826 (0.1 mg/kg, p.o.) administered 1.5 hr after antigen inhalation, also inhibited LAR (p less than 0.05). Analysis of BAL fluid revealed that DSCG and MCI-826 significantly inhibited the increase in eosinophils (p less than 0.05). These data suggest that leukotriene plays an important role in the development of the pathogenesis of LAR, and that our model is an useful experimental model for investigating the mechanisms of LAR and examining the effects of several anti-asthmatic drugs on LAR.