Effect of aliphatic alcohols on the conformation of poly (l-ornithine hydrobromide) as studied by square-pulse and reversing-pulse electric birefringence

The electric birefringence and circular dichroism spectra of poly(l-ornithine hydrobromide) have been measured in ethanol/water, 2-propanol/water and tertiary butyl alcohol/water mixtures of various compositions. This charged polypeptide underwent a transition from the coil conformation to the helical conformation at high alcohol content in every case tested. Anomalous birefringence signals, indicative of a field-induced helix-to-coil transition. were observed at high electric fields only in the case of ethanol/water mixtures. The reversing-pulse electric birefringence of this polypeptide has been studied in ethanol/water mixtures and in neutral aqueous solution. Upon rapid reversal of the pulse field, no transient could be observed. This confirms that the electric-field orientation of poly(l-ornithine hydrobromide) results predominantly from the contribution of the counterion-induced dipole moment, regardless of its molecular conformations. It is very probable that the backbone permanent dipole moment of the helical conformation is largely suppressed by the counterion-induced dipole moment in the ionized form.     

Electric field-induced conformational change of poly(L-lysine) studied by transient electric birefringence

Transient electric birefringence measurements on poly(L -lysine hydrobromide) in methanol–water mixtures have been carried out at various solvent compositions in the vicinity of the helix–coil transition region (from 87 to 98 vol % methanol). Anomalous birefringence transients were observed between 90 and 95 vol % methanol above a threshold field strength. A distinct difference between the responses to weak and strong electric fields was noticed over a narrow range of the solvent composition. The effects of polymer concentration and temperature on the field-strength dependence of the birefringence were studied at a solvent composition of 90 vol % methanol where the anomalous transients appeared most clearly. The double logarithmic plots of the steady-state specific birefringence versus the square of field strength for different concentrations and temperatures could be superimposed by shifting them horizontally along the abscissa. The threshold field strength which was determined from the shift factor decreased with decreasing concentration. The results provide further evidence that strong electric fields can cause a helix–coil transition in this system under favorable conditions.     

Periostin Links Mechanical Strain to Inflammation in Abdominal Aortic Aneurysm

Aims

Abdominal aortic aneurysms (AAAs) are characterized by chronic inflammation, which contributes to the pathological remodeling of the extracellular matrix. Although mechanical stress has been suggested to promote inflammation in AAA, the molecular mechanism remains uncertain. Periostin is a matricellular protein known to respond to mechanical strain. The aim of this study was to elucidate the role of periostin in mechanotransduction in the pathogenesis of AAA.

Methods and Results

We found significant increases in periostin protein levels in the walls of human AAA specimens. Tissue localization of periostin was associated with inflammatory cell infiltration and destruction of elastic fibers. We examined whether mechanical strain could stimulate periostin expression in cultured rat vascular smooth muscle cells. Cells subjected to 20% uniaxial cyclic strains showed significant increases in periostin protein expression, focal adhesion kinase (FAK) activation, and secretions of monocyte chemoattractant protein-1 (MCP-1) and the active form of matrix metalloproteinase (MMP)-2. These changes were largely abolished by a periostin-neutralizing antibody and by the FAK inhibitor, PF573228. Interestingly, inhibition of either periostin or FAK caused suppression of the other, indicating a positive feedback loop. In human AAA tissues in ex vivo culture, MCP-1 secretion was dramatically suppressed by PF573228. Moreover, in vivo, periaortic application of recombinant periostin in mice led to FAK activation and MCP-1 upregulation in the aortic walls, which resulted in marked cellular infiltration.

Conclusion

Our findings indicated that periostin plays an important role in mechanotransduction that maintains inflammation via FAK activation in AAA.     

Comparison of patient-specific intensity modulated radiation therapy quality assurance for the prostate across multiple institutions

AimTo evaluate the success of a patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA) practice for prostate cancer patients across multiple institutions using a questionnaire survey.BackgroundThe IMRT QA practice involves different methods of dose distribution verification and analysis at different institutions.Materials and MethodsTwo full-arc volumetric modulated arc therapy (VMAT) plan and 7 fixed-gantry IMRT plan with DMLC were used for patient specific QA across 22 institutions. The same computed tomography image and structure set were used for all plans. Each institution recalculated the dose distribution with fixed monitor units and without any modification. Single-point dose measurement with a cylindrical ionization chamber and dose distribution verification with a multi-detector or radiochromic film were performed, according to the QA process at each institution.ResultsTwenty-two institutions performed the patient-specific IMRT QA verifications. With a single-point dose measurement at the isocenter, the average difference between the calculated and measured doses was 0.5 ± 1.9%. For the comparison of dose distributions, 18 institutions used a two or three-dimensional array detector, while the others used Gafchromic film. In the γ test with dose difference/distance-to-agreement criteria of 3%?3 mm and 2%?2 mm with a 30% dose threshold, the median gamma pass rates were 99.3% (range: 41.7%–100.0%) and 96.4% (range: 29.4%–100.0%), respectively.ConclusionThis survey was an informative trial to understand the verification status of patient-specific IMRT QA measurements for prostate cancer. In most institutions, the point dose measurement and dose distribution differences met the desired criteria.     

Effect of epidermal growth factor on intestinal adaptation after allogeneic small bowel transplantation in rats

We reported that epidermal growth factor (EGF) stimulated graft adaptation in a rat model of syngeneic small bowel transplantation. However, graft rejection is a severe problem with clinical small bowel transplantation, because small intestinal wall contains large amounts of lymphoid tissue. Studies were performed to investigate the effect of EGF on allogeneic graft adaptation after small bowel transplantation in rats treated with an immunosuppressant FK506. The transplanted animals received intraperitoneally EGF or saline (untreated) after surgery and were examined for analysis one week later. EGF-treated group markedly enhanced the water absorption and induction of sodium glucose cotransporter (SGLTI) as compared with EGF-untreated group. EGF-treated group also increased the mucosal crypt depth and its cell proliferating rate, although there was no significant difference in the mucosal villus height between the two groups. These results indicate that EGF accelerates intestinal allograft adaptation in part by the recovery of mucosal structure and function after small bowel transplantation in rats. EGF may have relevance to promote graft function in clinical small intestinal transplantation.     

Dynamic Changes in the Distribution of Minerals in Relation to Phytic Acid Accumulation during Rice Seed Development

Phytic acid (inositol hexakisphosphate [InsP₆]) is the storage compound of phosphorus in seeds. As phytic acid binds strongly to metallic cations, it also acts as a storage compound of metals. To understand the mechanisms underlying metal accumulation and localization in relation to phytic acid storage, we applied synchrotron-based x-ray microfluorescence imaging analysis to characterize the simultaneous subcellular distribution of some mineral elements (phosphorus, calcium, potassium, iron, zinc, and copper) in immature and mature rice (Oryza sativa) seeds. This fine-imaging method can reveal whether these elements colocalize. We also determined their accumulation patterns and the changes in phosphate and InsP₆ contents during seed development. While the InsP₆ content in the outer parts of seeds rapidly increased during seed development, the phosphate contents of both the outer and inner parts of seeds remained low. Phosphorus, calcium, potassium, and iron were most abundant in the aleurone layer, and they colocalized throughout seed development. Zinc was broadly distributed from the aleurone layer to the inner endosperm. Copper localized outside the aleurone layer and did not colocalize with phosphorus. From these results, we suggest that phosphorus translocated from source organs was immediately converted to InsP₆ and accumulated in aleurone layer cells and that calcium, potassium, and iron accumulated as phytic acid salt (phytate) in the aleurone layer, whereas zinc bound loosely to InsP₆ and accumulated not only in phytate but also in another storage form. Copper accumulated in the endosperm and may exhibit a storage form other than phytate.The transport of nutrients into developing seeds has received considerable attention. During the grain-filling stage, plants remobilize and transport nutrients distributed throughout the vegetative source organs into seeds. Plant seeds contain large amounts of phosphorus (P) in organic form, which supports growth during the early stages of seedling development. Most of the P in seeds is stored in the form of phytic acid (inositol hexakisphosphate [InsP₆]). Seeds also accumulate mineral nutrients such as potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn), which are used in seedling growth. Phytic acid acts as a strong chelator of metal cations and binds them to form phytate, a salt of InsP₆ (Lott et al., 2002; Raboy, 2009). During germination, phytate is decationized and hydrolyzed by phytases, and then inorganic phosphates, inositol, and various minerals are released from the phytate (Loewus and Murthy, 2000). Phytate accumulates within protein bodies, generally of vacuolar origin, in seed storage cells and is usually concentrated in spherical inclusions called globoids. Many studies of the elemental composition of phytate in seeds have been published. Energy-dispersive x-ray microanalyses of many plant species have revealed that, other than P, globoids contain mainly K and Mg as well as low levels of Ca, Mn, Fe, and Zn (Lott, 1984; Lott et al., 1995; Wada and Lott, 1997). This indicates that phytate is a mixed salt of these cations.Whether all storage metal elements can bind equally to InsP₆ is not known, although most elements are thought to exist in seeds in the form of phytate (Raboy, 2009). To form phytate, P and the other elements must be present in the same place. Therefore, determination of the precise locations of P and other elements in seed tissues makes it possible to judge whether an element exists in the form of phytate. Differences in metal distribution with P might suggest a storage form other than phytate. For determining distributions, synchrotron-based x-ray microfluorescence (µ-XRF) imaging utilizing an x-ray microbeam is a powerful tool. The microbeam excites the elements, thereby revealing the details of their spatial distribution. The development of focusing optics for high-energy x-rays using a Kirkpatrick-Baez mirror raises the imaging resolution of elements in µ-XRF analysis. A focal spot size smaller than 1 µm with x-ray energy as high as 100 keV enables detection of the subcellular distribution of elements in plant tissues (Fukuda et al., 2008; Takahashi et al., 2009).Whether there is an order in the affinity of elements for phytic acid in plant cells remains unknown. The stability of InsP₆-metal complexes has been estimated by in vitro titration (Maddaiah et al., 1964; Vohra et al., 1965; Persson et al., 1998). The binding strength of InsP₆ with metal is stronger for Zn and Cu than for Fe, Mn, and Ca. We also do not know if the mineral composition of phytate in seeds is determined by the relative abundance of these elements in the seed or by their biochemical characteristics. As a first step to address these issues, we examined the simultaneous changes in the distribution of P and metal elements during seed development using µ-XRF imaging analysis.Our objective in this study was to observe the dynamic changes in the distribution of some nutritionally important minerals (P, Ca, K, Fe, Zn, and Cu) in relation to the accumulation of phytic acid during rice (Oryza sativa) seed development.     

Radiation Dose Reduction Efficiency of Buildings after the Accident at the Fukushima Daiichi Nuclear Power Station

Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55±0.04, 0.15±0.02, and 0.19±0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites.