Induction of donor-specific tolerance to cardiac xenografts in utero

BACKGROUND: Problems associated with heart transplantation, such as shortage of suitable organs and the side effects of immunosuppressive therapy, are especially serious for patients in the pediatric age group. Induction of donor-specific immunologic tolerance without immunosuppressive drugs would be ideal for clinical organ transplantation. In this study, we used a vascularized cardiac xenograft model to achieve donor-specific unresponsiveness without immunosuppression by manipulating the intrauterine immune response. METHODS: Lewis rats and Golden Syrian hamsters were used as the recipients and donors, respectively. Donor bone marrow cells (15 x 10(6) in 0.05 mL) were injected into each fetus of pregnant Lewis rats on days 9 (n = 2) and 16 (n = 2) of gestation. Donor hearts were heterotopically transplanted into each surviving (n = 8, n = 5) fetus of the Lewis rats at 8 weeks of age. Donor hearts were also transplanted into untreated rats as controls (n = 8). RESULTS: The mean cardiac xenograft survival time was 2.5 +/- 0.5, 7.4 +/- 4.1, and 2.8 +/- 0.8 days in the control group, gestational day 9 group, and gestational day 16 group, respectively. Chromosomal analysis of the day 9 group showed Golden Syrian hamster chromosomes as well as Lewis rat chromosomes. CONCLUSIONS: Cardiac xenograft survival was significantly prolonged by intrauterine exposure to xenograft bone marrow cells on day 9 but not on day 16 of gestation. Cardiac xenograft survival and chromosomal analysis of the recipient bone marrow suggested that chimerism was achieved between Golden Syrian hamsters and Lewis rats. Cardiac xenotransplantation may be possible by induction of donor-specific tolerance in utero.     

A case of unique communication between blind-ending ectopic ureter and ipsilateral hemi-hematocolpometra in uterus didelphys

Uterus didelphys with double vagina and hemi-vaginal atresia is a rare syndrome of congenital anomalies. A 17-year-old girl had a right blind-ending ectopic ureter, the proximal end of which communicated with the ipsilateral uterine cervix of uterus didelphys. The patient presented with vaginal urinary incontinence after incision of the vaginal wall for right hemi-hematocolpometra. Following various examinations, the ipsilateral kidney was found to be absent. The ectopic ureter and communicating duct were resected, and the fistula was closed. The genesis of malformation of the female genitalia and urinary tract resulting in such a unique communication is discussed. The importance of preoperative meticulous examinations, including cysto-genitography, pelvic magnetic resonance imaging and panendoscopy with the patient under anesthesia, is emphasized.     

Newly-developed catheter for cardio-renal assist during intraaortic balloon counterpulsation

A new catheter was developed for the cardio-renal assist during intra-aortic balloon counterpulsation. The catheter consists of both a large balloon of conventional IAB (TMP balloon) located at the distal end of the catheter and an additional small balloon 10 cm distant from the large balloon with common lumen and single shaft. Experimental study was carried out in the mock circulatory system simulating the descending aorta employing a conventional IAB catheter as a control. It was demonstrated that the flow in the mid portion between both balloons could be increased maximally by as much as 28% of that of the control under the continuous flow and 214% under the pulsatile flow. The double balloon catheter was considered to improve the renal perfusion as well as the coronary perfusion.     

Three-dimensional porous graphene-based ultra-lightweight aerofoam exhibiting good thermal insulation

Three-dimensional (3D) architectures of graphene and carbon nanotubes (CNTs) were prepared via the in situ self-assembly of graphene oxide and carboxyl-functionalized CNTs by mild chemical reduction and freeze-drying. The prepared 3D architectures exhibited densities of 7.35–9.68 mg/mL and thermal conductivities of 0.0192–0.0414 W/mK. These features were created by a highly porous structure, including millimeter-, micrometer-, and nanometer-scale pores. A number of analytical techniques were used to characterize the 3D architectures of graphene. The highly porous graphene-based aerofoams exhibited low densities, good thermal stabilities, and low thermal conductivities, making them excellent candidates for application in thermal protection materials, as well as in super capacitors and energy storage systems.     

Magnetoplumbite-Corundum Phase Equilibria in the System Sr─Fe─Al─O at 1100°C

The phase relations in the region of the Fe₂O₃- and Al₂O₃-rich sides of the quaternary system SrO─Fe₂O₃–Al₂O₃–B₂O₃ and the location of conjugation lines between magnetoplumbite solid solution SrO·(6 − x)Fe₂O₃·xAl₂O₃ and corundum (α-Fe₂O₃, α-Al₂O₃) phases were determined at 1100°C in air by using the flux-growth method based on the Ostwald ripening mechanism. Activity–composition relations and the lattice parameters along the magnetoplumbite solid solutions were also obtained.     

Molecular dynamics study of the interfacial strength between carbon fiber and phenolic resin

The interfacial strength between carbon fiber and phenolic resin is studied using molecular dynamics simulations to demonstrate that carbon fiber-reinforced carbon matrix composites (C/C composites) have improved tensile strength. Simulations are performed using two carbon fiber models, one of which has only carbon atoms and the other has carbon atoms and some fluorinated carbon groups. The carbon fiber models are regarded as two-layer graphite, and the phenolic resin model is treated as cross-linked structures. All force field parameters are based on the Dreiding force field. The tensile stress and interfacial fracture energy are calculated for the estimation of the interfacial strength. The results show that the model including the fluorinated carbon groups has lower interfacial strength than the model having only carbon atoms, up to a certain coating ratio of fluorinated carbon groups. Similarly, within the limits of the coating ratio, the interfacial fracture energy of the fluorinated carbon fiber model is lower than that of carbon fiber model having only carbon atoms.     

Analysis of structure characteristics in laminated graphene oxide nanocomposites using molecular dynamics simulation

The characteristics of laminated graphene oxide (LGO) nanocomposite, which are expected to be used for highly functional composites, are known to be related to its microstructure. In this study, we investigate the influences of hydrogen-bonding and cross-linked network structures on the initial stiffness and yield stress, using molecular dynamics simulations. Our results show that each structure increases the mechanical properties, and the combination of these structures strengthens the properties. Moreover, we found that the physical origin of the enhancement is cross-linked networks that generate stretched polymers connecting graphene sheets. Our study concludes by suggesting an appropriate selection of materials for high-performance LGO nanocomposites.     

Comparison of a viscoelastic frictional interface theory with a kinetic crack growth theory in unidirectional composites

In this paper we compare a frictional interface theory for fiber and matrix load sharing with a kinetic crack growth theory as applicable to the failure of unidirectional composites. First we formulate the creep lifetime prediction based on the viscoelastic frictional interface theory, and then we determine a parameter in the kinetic crack growth theory by fitting it to the frictional interface theory in terms of the creep lifetime prediction. Times-to-failure under a constant strain rate condition are then derived by these two models, and they are compared. The residual strengths after interrupted loading are also compared.