Kota Yamamoto

Induction of LDL receptor-related protein during the differentiation of monocyte-macrophages. Possible involvement in the atherosclerotic process.

The low-density lipoprotein receptor-related protein (LRP) is a multifunctional receptor that binds to apolipoprotein E-rich lipoproteins, lipoprotein lipase, alpha 2-macroglobulin, lactoferrin, and tissue plasminogen activator. We studied the mRNA expression of LRP in human monocyte-derived macrophages and THP-1 cells. mRNA expression of LRP was induced during cell differentiation from human monocytes to macrophages or after incubation with phorbol ester (tetradecanoylphorbol acetate 100 ng/mL) in THP-1 cells, and the addition of 30 ng/mL macrophage colony-stimulating factor further enhanced LRP expression. These results indicated that the expression of LRP depended on the stage of differentiation and maturation of monocytic cells. mRNA expression of LRP was also enhanced in human monocyte-derived macrophages in the presence of acetylated low-density lipoprotein and in aorta of rabbits fed a high-cholesterol diet. We hypothesize that the LRP induced in monocyte-derived macrophages is involved in the initial process of atherosclerosis by interacting with its multiple ligands.

Photoemission evidence for a Mott-Hubbard metal-insulator transition in VO2

The temperature (T) dependent metal-insulator transition (MIT) in VO2 is investigated using bulk sensitive hard x-ray (� 8 keV) valence band, core level, and V 2p-3d resonant photoemission spectroscopy (PES). The valence band and core level spectra are compared with full-multiplet cluster model calculations including a coherent screening channel. Across the MIT, V 3d spectral weight transfer from the coherent (d 1 C final) states at Fermi level to the incoherent (d 0 +d 1 L final) states, corresponding to the lower Hubbard band, lead to gap-formation. The spectral shape changes in V 1s and V 2p core levels as well as the valence band are nicely reproduced from a cluster model calculations, providing electronic structure parameters. Resonant-PES finds that the d 1 L states resonate across the V 2p-3d threshold in addition to the d 0 and d 1 C states. The results support a Mott-Hubbard transition picture for the first order MIT in VO2. PACS numbers: 79.60.-i, 71.30.+h VO2, a d 1 electron system, exhibits a sharp first-order metal-insulator transition (MIT) as a function of temperature (T), at TMI = 340 K. 1 The high-T metal phase has a rutile (R) structure, while the low-T insulating phase has a monoclinic (M1) structure with zig-zag type pairing of V atoms along the c-axis. 2 Magnetically, the metallic R phase shows enhanced susceptibility (�) with an effective mass m ∗ /m � 6, while the insulating M1 phase is non

Vein graft adaptation and fistula maturation in the arterial environment

Veins are exposed to the arterial environment during two common surgical procedures, creation of vein grafts and arteriovenous fistulae (AVF). In both cases, veins adapt to the arterial environment that is characterized by different hemodynamic conditions and increased oxygen tension compared with the venous environment. Successful venous adaptation to the arterial environment is critical for long-term success of the vein graft or AVF and, in both cases, is generally characterized by venous dilation and wall thickening. However, AVF are exposed to a high flow, high shear stress, low-pressure arterial environment and adapt mainly via outward dilation with less intimal thickening. Vein grafts are exposed to a moderate flow, moderate shear stress, high-pressure arterial environment and adapt mainly via increased wall thickening with less outward dilation. We review the data that describe these differences, as well as the underlying molecular mechanisms that mediate these processes. Despite extensive research, there are few differences in the molecular pathways that regulate cell proliferation and migration or matrix synthesis, secretion, or degradation currently identified between vein graft adaptation and AVF maturation that account for the different types of venous adaptation to arterial environments.

Non-thermal hot electrons ultrafastly generating hot optical phonons in graphite

Investigation of the non-equilibrium dynamics after an impulsive impact provides insights into couplings among various excitations. A two-temperature model (TTM) is often a starting point to understand the coupled dynamics of electrons and lattice vibrations: the optical pulse primarily raises the electronic temperature Tel while leaving the lattice temperature Tl low; subsequently the hot electrons heat up the lattice until Tel = Tl is reached. This temporal hierarchy owes to the assumption that the electron-electron scattering rate is much larger than the electron-phonon scattering rate. We report herein that the TTM scheme is seriously invalidated in semimetal graphite. Time-resolved photoemission spectroscopy (TrPES) of graphite reveals that fingerprints of coupled optical phonons (COPs) occur from the initial moments where Tel is still not definable. Our study shows that ultrafast-and-efficient phonon generations occur beyond the TTM scheme, presumably associated to the long duration of the non-thermal electrons in graphite.

Implantable tissue-engineered blood vessels from human induced pluripotent stem cells

Derivation of functional vascular smooth muscle cells (VSMCs) from human induced pluripotent stem cells (hiPSCs) to generate tissue-engineered blood vessels (TEBVs) holds great potential in treating patients with vascular diseases. Herein, hiPSCs were differentiated into alpha-smooth muscle actin (α-SMA) and calponin-positive VSMCs, which were seeded onto polymer scaffolds in bioreactors for vascular tissue growth. A functional TEBV with abundant collagenous matrix and sound mechanics resulted, which contained cells largely positive for α-SMA and smooth muscle myosin heavy chain (SM-MHC). Moreover, when hiPSC-derived TEBV segments were implanted into nude rats as abdominal aorta interposition grafts, they remained unruptured and patent with active vascular remodeling, and showed no evidence of teratoma formation during a 2-week proof-of-principle study. Our studies represent the development of the first implantable TEBVs based on hiPSCs, and pave the way for developing autologous or allogeneic grafts for clinical use in patients with vascular disease.

Time-resolved photoemission apparatus achieving sub-20-meV energy resolution and high stability

The paper describes a time- and angle-resolved photoemission apparatus consisting of a hemispherical analyzer and a pulsed laser source. We demonstrate 1.48-eV pump and 5.92-eV probe measurements at the ⩾10.5-meV and ⩾240-fs resolutions by use of fairly monochromatic 170-fs pulses delivered from a regeneratively amplified Ti:sapphire laser system operating typically at 250 kHz. The apparatus is capable to resolve the optically filled superconducting peak in the unoccupied states of a cuprate superconductor, Bi2Sr2CaCu2O(8 + δ). A dataset recorded on Bi(111) surface is also presented. Technical descriptions include the followings: A simple procedure to fine-tune the spatio-temporal overlap of the pump-and-probe beams and their diameters; achieving a long-term stability of the system that enables a normalization-free dataset acquisition; changing the repetition rate by utilizing acoustic optical modulator and frequency-division circuit.

Overexpression of human lipoprotein lipase enhances uptake of lipoproteins containing apolipoprotein B-100 in transfected cells.

To investigate the role in lipoprotein metabolism of lipoprotein lipase (LPL) secreted by tissues, we established two cell lines. Fusion plasmids containing either human LPL cDNA or antisense LPL cDNA under control of the cytomegalovirus promoter were transfected into Chinese hamster ovary (CHO) cells, designated as CHO-LPL and CHO-anti-LPL, respectively. CHO-LPL constitutively produced a high level of LPL, whereas CHO-anti-LPL produced a minimal level. When very-low-density lipoprotein (VLDL) was incubated with CHO-LPL, VLDL triglycerides were hydrolyzed, intermediate-density lipoprotein (IDL) was produced, and apolipoprotein E contents increased. CHO-LPL took up and degraded 125I-VLDL at 37 degrees C four times more strongly than did CHO-anti-LPL. Whereas the degradation of apolipoprotein E-deficient VLDL was only 12% that of normal VLDL in CHO-LPL, structural changes of the lipoprotein, including apolipoprotein E expression on the lipoprotein surface, may be important for the cellular uptake of VLDL. Furthermore, we found that binding at 4 degrees C of VLDL and LDL to CHO-LPL was greater than to CHO-anti-LPL, and this binding difference was abolished by washing the cells with heparin. This suggests that cell surface LPL plays a role in the binding of lipoproteins to the cells. We conclude that both the composition of VLDL particles and their cellular binding are influenced by LPL secreted by cells, both of which may enhance the cellular uptake of VLDL.

The mouse aortocaval fistula recapitulates human arteriovenous fistula maturation

Several models of arteriovenous fistula (AVF) have excellent patency and help in understanding the mechanisms of venous adaptation to the arterial environment. However, these models fail to exhibit either maturation failure or fail to develop stenoses, both of which are critical modes of AVF failure in human patients. We used high-resolution Doppler ultrasound to serially follow mice with AVFs created by direct 25-gauge needle puncture. By day 21, 75% of AVFs dilate, thicken, and increase flow, i.e., mature, and 25% fail due to immediate thrombosis or maturation failure. Mature AVF thicken due to increased amounts of smooth muscle cells. By day 42, 67% of mature AVFs remain patent, but 33% of AVFs fail due to perianastomotic thickening. These results show that the mouse aortocaval model has an easily detectable maturation phase in the first 21 days followed by a potential failure phase in the subsequent 21 days. This model is the first animal model of AVF to show a course that recapitulates aspects of human AVF maturation.

Disturbed shear stress reduces Klf2 expression in arterial-venous fistulae in vivo

Laminar shear stress (SS) induces an antiproliferative and anti‐inflammatory endothelial phenotype and increases Klf2 expression. We altered the diameter of an arteriovenous fistula (AVF) in the mouse model to determine whether increased fistula diameter produces disturbed SS in vivo and if acutely increased disturbed SS results in decreased Klf2 expression. The mouse aortocaval fistula model was performed with 22, 25, or 28 gauge needles to puncture the aorta and the inferior vena cava. Duplex ultrasound was used to examine the AVF and its arterial inflow and venous outflow, and SS was calculated. Arterial samples were examined with western blot, immunohistochemistry, and immunofluorescence analysis for proteins and qPCR for RNA. Mice with larger diameter fistulae had diminished survival but increased AVF patency. Increased SS magnitudes and range of frequencies were directly proportional to the needle diameter in the arterial limb proximal to the fistula but not in the venous limb distal to the fistula, with 22‐gauge needles producing the most disturbed SS in vivo. Klf2 mRNA and protein expression was diminished in the artery proximal to the fistula in proportion to increasing SS. Increased fistula diameter produces increased SS magnitude and frequency, consistent with disturbed SS in vivo. Disturbed SS is associated with decreased mRNA and protein expression of Klf2. Disturbed SS and reduced Klf2 expression near the fistula are potential therapeutic targets to improve AVF maturation.

Favorable outcomes of very elderly patients with critical limb ischemia who undergo distal bypass surgery

OBJECTIVE To determine the midterm outcomes of distal bypass surgery for very elderly patients, and to determine the ideal candidates for this procedure. METHODS Of 268 consecutive patients (328 limbs) with critical limb ischemia who were treated between 2006 and 2013, 106 (126 limbs) underwent distal bypass and were retrospectively reviewed. Nineteen patients (22 limbs) were aged ≥80 years (very elderly group) and 87 patients (104 limbs) were aged <80 years (control group). RESULTS The baseline characteristics differed between the 2 groups in terms of regular hemodialysis rate (very elderly group, 4 [21%] vs control group, 60 [69%]; P = .0002) and the Charlson comorbidity index (very elderly group, 3.2 ± 1.7 vs control group, 5.0 ± 2.0; P = .0005). According to the Rutherford category of limb ischemia (4/5/6), the very elderly and control groups were classified as 5/17/0 and 11/87/6, respectively (P = .18). Before the surgery, 17 patients (77%) and 67 patients (64%) were ambulatory in the very elderly and control groups, respectively. At follow-up at 29 ± 22 months, the rates of primary (P = .33) and secondary patency (P = .14), limb salvage (P = .50), survival (P = .26), amputation-free survival (P = .42), major adverse limb event and also perioperative death (P = .11), and major adverse cardiovascular events (P = .36) did not significantly differ between the groups. In multivariate analysis, a history of coronary artery disease (hazard ratio [HR], 2.7; 95% confidence interval [CI], 1.3-5.9; P = .005), preoperative nonambulatory status (HR, 4.2; 95% CI, 2.1-8.1; P < .0001), and serum albumin levels <3 g/dL (HR, 2.7; 95% CI, 1.3-5.4; P = .01) were significantly related to poor amputation-free survival. Thirteen patients (59%) remained ambulatory at the latest follow-up. In 91 patients (110 limbs) with tissue loss, the Society for Vascular Surgery lower extremity threatened limb classification system: risk stratification based on Wound, Ischemia, and foot Infection classification stages 3 and 4 negatively affected complete wound healing, according to multivariate analysis (HR, 0.34; 95% CI, 0.20-0.61; P = .0005). CONCLUSIONS A very elderly age should not preclude a patient from undergoing distal bypass surgery. A history of coronary artery disease, a nonambulatory status, and hypoalbuminemia, along with the Wound, Ischemia, and foot Infection classification for patients with tissue loss, should be carefully considered to obtain the most benefit from distal bypass surgery.