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Mechanical stress is involved in the onset of sports-related enthesopathy. Although the amount of exercise undertaken is a recognized problem during disease onset, changes in muscle contraction type are also involved in the increase in mechanical stress during exercise. This study aimed to clarify the effects of increased mechanical stress associated with muscle contraction type and amount of exercise on enthesis. Twenty mice underwent treadmill exercise, and the muscle contraction type and overall load during exercise were adjusted by varying the angle and speed conditions. Histological analysis was used to the cross-sectional area of the muscle; area of the enthesis fibrocartilage (FC), and expression of inflammation-, degeneration-, and calcification-related factors in the FC area. In addition, the volume and structure of the bone and FC area were examined using microcomputer imaging. Molecular biological analysis was conducted to compare relative expression levels of inflammation and cytokine-related factors in tendons. The Overuse group, which increased the amount of exercise, showed no significant differences in parameters compared to the sedentary mice (Control group). The mice subjected to slow-speed downhill running (Misuse group) showed pathological changes compared to the Control and Overuse groups, despite the small amount of exercise. Thus, the enthesis FC area may be altered by local mechanical stress that would be increased by eccentric muscle contraction rather than by mechanical stress that increases with the overall amount of exercise. Clinical Significance: The muscle contraction type might be more involved in the onset of sports-related enthesopathy rather than the amount of exercise.

Although mechanical signals presented by the extracellular matrix are known to regulate many essential cell functions, the specific effects of these interactions, particularly in response to dynamic and heterogeneous cues, remain largely unknown. Here, we introduce a modular semisynthetic approach to create protein-polymer hydrogel biomaterials that undergo reversible stiffening in response to user-specified inputs. Employing a novel dual-chemoenzymatic modification strategy, we create fusion protein-based gel crosslinkers that exhibit stimuli-dependent intramolecular association. Linkers based on calmodulin yield calcium-sensitive materials, while those containing the photosensitive LOV2 (light, oxygen, and voltage sensing domain 2) protein give phototunable constructs whose moduli can be cycled on demand with spatiotemporal control about living cells. We exploit these unique materials to demonstrate the significant role that cyclic mechanical loading plays on fibroblast-to-myofibroblast transdifferentiation in three-dimensional (3D) space. Our moduli-switchable materials should prove useful for studies in mechanobiology, providing new avenues to probe and direct matrix-driven changes in 4D cell physiology.

It has been debated whether the onset of knee osteoarthritis is initiated in cartilage or subchondral bone. The purpose of this study was to clarify the effects of increasing or decreasing joint instability on cartilage degeneration and subchondral bone changes in knee OA by comparing different models of joint instability.We used the anterior cruciate ligament transection (ACL-T) model and the destabilization of the medial meniscus (DMM) model. In addition, we created a controlled abnormal tibial translation (CATT) model and a controlled abnormal tibial rotation (CATR) model. We performed joint instability analysis, micro-computed tomography analysis, histological and immunohistological analysis in 4 and 6 weeks.The CATT group suppressed joint instability in the ACL-T group (6 weeks; P = 0.032), and the CATR group suppressed joint instability in the DMM group (6 weeks; P = 0.032). Chondrocyte hypertrophy in the ACL-T and DMM groups was increased compared to the Sham group (6 weeks; [ACL-T vs Sham], P = 0.002, 95%CI [5.983-33.025]; [DMM vs Sham], P = 0.022, 95%CI [1.691-28.733]). In the subchondral bone, the BV/TV in the DMM and CATR groups was increased compared to the ACL-T and CATT groups (6 weeks; [DMM vs ACL-T], P = 0.002, 95%CI [7.404-37.582]; [DMM vs CATT], P = 0.014, 95%CI [2.881-33.059]; [CATR vs ACL-T], P = 0.006, 95%CI [4.615-34.793]; [CATR vs CATT], P = 0.048, 95%CI [0.092-30.270]).This study showed that joint instability promotes chondrocyte hypertrophy, but subchondral bone changes were influenced by differences in ACL and meniscus function.

ObjectiveThe effect of the type of mechanical stress on OA onset has not been clarified. The aim of this study was to establish a new model that reproduces the type and increase and decrease of mechanical stress in vivo and to clarify the differences in the mechanism of knee OA onset and progression among the models.DesignTo reproduce the difference in mechanical stress, we used the anterior cruciate ligament transection (ACL-T) model and the destabilization of the medial meniscus (DMM) model. In addition, we created a controlled abnormal tibial translation (CATT) model and a controlled abnormal tibial rotation (CATR) model that suppressed the joint instability of the ACL-T and DMM model, respectively. These four models reproduced the increase and decrease in shear force due to joint instability and compressive stress due to meniscal dysfunction. We performed joint instability analysis with soft X-ray, micro computed tomography analysis, histological analysis, and immunohistological analysis in 4 and 6 weeks.ResultsJoint instability decreased in the CATT and CATR groups. The meniscus deviated in the DMM and CATR groups. Chondrocyte hypertrophy increased in the ACL-T and DMM groups with joint instability. In the subchondral bone, bone resorption was promoted in the ACL-T and CATT groups, and bone formation was promoted in the DMM and CATR groups.ConclusionsIncreased shear force causes articular cartilage degeneration and osteoclast activation in the subchondral bone. In contrast, increased compressive stress promotes bone formation in the subchondral bone earlier than articular cartilage degeneration occurs.

Objective Joint instability and meniscal dysfunction contribute to the onset and progression of knee osteoarthritis (OA). In the destabilization of the medial meniscus (DMM) model, secondary OA occurs due to the rotational instability and increases compressive stress resulting from the meniscal dysfunction. We created a new controlled abnormal tibial rotation (CATR) model that reduces the rotational instability that occurs in the DMM model. So, we aimed to investigate whether rotational instability affects articular cartilage degeneration using the DMM and CATR models, as confirmed using histology and immunohistochemistry. Design Twelve-week-old male mice were randomized into 3 groups: DMM group, CATR group, and INTACT group (right knee of the DMM group). After 8 and 12 weeks, we performed the tibial rotational test, safranin-O/fast green staining, and immunohistochemical staining for tumor necrosis factor (TNF)-α and metalloproteinase (MMP)-13. Results The rotational instability in the DMM group was significantly higher than that of the other groups. And articular cartilage degeneration was higher in the DMM group than in the other groups. However, meniscal degeneration was observed in both DMM and CATR groups. The TNF-α and MMP-13 positive cell rates in the articular cartilage of the CATR group were lower than those in the DMM group. Conclusions We found that the articular cartilage degeneration was delayed by controlling the rotational instability caused by meniscal dysfunction. These findings suggest that suppression of rotational instability in the knee joint may be an effective therapeutic measure for preventing OA progression.

Cartilage degeneration is the main pathological component of knee osteoarthritis (OA), but no effective treatment for its control exists. Although exercise can inhibit OA, the abnormal joint movement with knee OA must be managed to perform exercise. Our aims were to determine how controlling abnormal joint movement and treadmill exercise can suppress cartilage degeneration, to analyze the tissues surrounding articular cartilage, and to clarify the effect of treatment. Twelve-week-old ICR mice (n = 24) underwent anterior cruciate ligament transection (ACL-T) surgery on their right knees and were divided into three groups as follows: ACL-T, animals in the walking group subjected to ACL-T, controlled abnormal joint movement (CAJM), and CAJM with exercise (CAJM + Ex) (n = 8/group). Walking-group animals were subjected to treadmill exercise 6 weeks after surgery, including walking for 18 m/min, 30 min/day, 3 days/week for 8 weeks. Safranin-O staining, hematoxylin-eosin staining, and immunohistochemical staining were performed. The OARSI (Osteoarthritis research Society international) score was lower in the CAJM group than in the ACL-T group and was even lower in the CAJM + Ex group. The CAJM group had a lower meniscal injury score than the ACL-T group, and the CAJM + Ex group demonstrated a less severe synovitis than the ACL-T and CAJM groups. The observed difference in the perichondrium tissue damage score depending on the intervention method suggests different therapeutic effects, that normalizing joint motion can solve local problems in the knee joint, and that the anti-inflammatory effect of treadmill exercise can suppress cartilage degeneration.

The healing ability of the anterior cruciate ligament (ACL) injury is very poor; however, it has recently been shown to undergo self-healing with conservative treatments. In this study, we evaluated the influence of the site of injury on the healing process after complete transverse tear of ACL using a rat model.A total of 58 skeletally mature Wistar rats were randomly assigned to various ACL injury groups: controlled abnormal movement-mid-portion (CAM-MP), controlled abnormal movement-femoral side (CAM-FS), ACL transection-mid-portion (ACLT-MP), or ACL transection-femoral side (ACLT-FS) injury groups. The ACL was completely transected in the mid-portion in the ACLT-MP and CAM-MP groups, and on the femoral side in the ACLT-FS and CAM-FS groups. Both CAM groups underwent extra-articular braking to control for abnormal tibial translation. The animals were allowed full cage activity until sacrifice postoperatively for histological and biomechanical assessment.Significant differences were found in the ratios of residual ligament lengths between the CAM-MP and CAM-FS groups, demonstrating the validity of each model. Spontaneous healing of the injured ACL was observed in the CAM-MP and CAM-FS groups but not in the ACLT-MP and ACLT-FS groups. The mechanical strength of the healing ACL did not differ between the CAM-MP and CAM-FS groups 8 weeks after injury; however, the former had better mechanical strength than the latter 12 weeks after the injury.ACL injuries in the mid-portion and on the femoral side may be treated with conservative therapy for spontaneous healing.

Summary Objective Abnormal load stress caused by joint instability has been reported to be one of the factors responsible for the development of osteoarthritis (OA). However, few studies have investigated the efficacy of exercise therapy for patients with knee instability-induced OA, and there are no specific treatment guidelines or effects for this form of OA. Therefore, the purpose of this study was to examine the effect of exercise treatments for joint instability in patients with knee OA by a systematic review. Design Systematic review. Results Searches in three databases, PubMed, Cochrane, and the Physiotherapy Evidence Database, yielded 14 articles that were scrutinized, and 6 articles that met the inclusion criteria were selected. Conclusions Exercise therapy focusing on joint instability, including muscle maintenance and strength training, and specific training targeting knee instability have no additional beneficial effects on knee joint instability. However, because of the benefits of treatment protocols based on patient attributes in exercise treatment focused on joint instability, it is necessary to investigate the effects in more detail in the future.

Vascularization remains an obstacle when engineering complex tissues for regeneration and disease modeling. Although progress has been made in recreating 3D vascular structures, challenges exist in generating a mature, functional endothelium. It is demonstrated that perfusing engineered microvessels with platelet‐rich plasma, a critical homeostatic component in vivo that is often overlooked in vitro, substantially transforms the endothelium, both maturing endothelial cells and improving functionality in 24 h. Platelets readily adhered to the exposed collagen‐I substrate through small gaps within engineered vessels without forming thrombi. The adherent platelets improve barrier function, enhance endothelial glycolysis, reduce thrombogenicity, and enrich smooth muscle cell growth surrounding the endothelium. These findings demonstrate that platelets are essential to the function of endothelium during vascular maturation and remodeling. This study sheds light on a potential strategy to engineer stable, implantable vascular networks., Perfusion of platelet‐rich plasma (PRP) substantially transforms the endothelium in engineered microvessels in 24 h. PRP increases vessel diameter, improves barrier function, enhances endothelial glycolysis, reduces thrombogenicity, and enriches smooth muscle cell growth surrounding the endothelium. This work provides a potential strategy to improve vascular maturation and remodeling in engineered complex tissues for implantation and disease modeling.

Objective Moderate mechanical stress is necessary for preserving the cartilage. The clinician empirically understands that prescribing only exercise will progress osteoarthritis (OA) for knee OA patients with abnormal joint movement. When prescribing exercise for OA, we hypothesized that degeneration of articular cartilage could be further prevented by combining interventions with the viewpoint of normalizing joint movement. Design Twelve-week-old ICR mice underwent anterior cruciate ligament transection (ACL-T) surgery in their right knee and divided into 4 groups: ACL-T, controlled abnormal joint movement (CAJM), ACL-T with exercise (ACL-T/Ex), CAJM with exercise (CAJM/Ex). Animals in the walking group were subjected to treadmill exercise 6 weeks after surgery, which included walking for 18 m/min, 30 min/d, 3 d/wk for 4 weeks. Joint instability was measured by anterior drawer test, and safranin-O staining and immunohistochemical staining were performed. Results OARSI (Osteoarthritis Research Society International) score of ACL-T/Ex group showed highest among 4 groups ( P < 0.001). And CAJM/Ex group was lower than ACL-T/Ex group. Positive cell ratio of IL-1β and MMP-13 in CAJM/Ex group was lower than ACL-T/Ex group ( P < 0.05). Conclusions We found that the state of the intra-articular environment can greatly influence the effect of exercise on cartilage degeneration, even if exercise is performed under the same conditions. In the CAJM/Ex group where joint movement was normalized, abnormal mechanical stress such as shear force and compression force accompanying ACL cutting was alleviated. These findings may highlight the need to consider an intervention to correct abnormal joint movement before prescribing physical exercise in the treatment of OA.

Engineered human capillaries reveal distinct contributions of hemodynamics and cytoadhesion in malaria parasite sequestration., Microcirculatory obstruction is a hallmark of severe malaria, but mechanisms of parasite sequestration are only partially understood. Here, we developed a robust three-dimensional microvessel model that mimics the arteriole-capillary-venule (ACV) transition consisting of a narrow 5- to 10-μm-diameter capillary region flanked by arteriole- or venule-sized vessels. Using this platform, we investigated red blood cell (RBC) transit at the single cell and at physiological hematocrits. We showed normal RBCs deformed via in vivo–like stretching and tumbling with negligible interactions with the vessel wall. By comparison, Plasmodium falciparum–infected RBCs exhibited virtually no deformation and rapidly accumulated in the capillary-sized region. Comparison of wild-type parasites to those lacking either cytoadhesion ligands or membrane-stiffening knobs showed highly distinctive spatial and temporal kinetics of accumulation, linked to velocity transition in ACVs. Our findings shed light on mechanisms of microcirculatory obstruction in malaria and establish a new platform to study hematologic and microvascular diseases.

Stem cell fate decisions are informed by physical and chemical cues presented within and by the extracellular matrix. Despite the generally attributed importance of extracellular cues in governing self-renewal, differentiation, and collective behavior, knowledge gaps persist with regard to the individual, synergistic, and competing effects that specific physiochemical signals have on cell function. To better understand basic stem cell biology, as well as to expand opportunities in regenerative medicine and tissue engineering, a growing suite of customizable biomaterials has been developed. These next-generation cell culture materials offer user-defined biochemical and biomechanical properties, increasingly in a manner that can be controlled in time and 3D space. This review highlights recent innovations in this regard, focusing on advances to culture and maintain stemness, direct fate, and to detect stem cell function using biomaterial-based strategies.

In order to explain the distribution of natural radiation level in the Asia, in situ measurements of dose rate in air due to terrestrial gamma radiation have been conducted in a total of 21 islands that belong to Ryukyu Islands (Ryukyu Archipelago), subtropical rejoin of southwest Japan. Car-borne surveys have also been carried out in Okinawa-jima, the biggest island of the archipelago. Based on the results for these measurements, arithmetic mean, the maximum and the minimum of the dose rates at 1 m in height from the unpaved soil ground in the archipelago were estimated to be 47, 165 and 8 nGy h(-1), respectively. A comparative study of car-borne data obtained prior to and subsequent to the 2011 Fukushima nuclear accident, as for Okinawa-jima, indicated that the nuclear accident has no impact on the environmental radiation at the present time.

A photodegradable material-based approach to generate endothelialized 3D vascular networks within cell-laden hydrogel biomaterials is introduced. Exploiting multiphoton lithography, microchannel networks spanning nearly all size scales of native human vasculature are readily generated with unprecedented user-defined 4D control. Intraluminal channel architectures of synthetic vessels are fully customizable, providing new opportunities for next-generation microfluidics and directed cell function.

A growing interest to probe and direct stem cell fate has fueled the ongoing development of a wide variety of polymer-based platforms for in vitro culture. Biomaterials with unique chemical and physical properties are afforded through careful selection of composition and can be engineered to mimic critical aspects of the native extracellular matrix. This chapter highlights recent progress in polymer design and development for 3D stem cell culture, comparing the advantages of both naturally and synthetic-based precursors. Special attention is given to natural materials derived from polysaccharides, peptides, and proteins, as well as smart synthetic polymer systems that exhibit responsiveness to environmental stimuli (e.g., electricity, temperature, enzyme, light, heat, pH).

Photopolymerizable hydrogels derived from naturally occurring polymers have attracted significant interest in tissue-engineering applications due to their excellent biocompatibility, hydrophilic nature favourable for cell ingrowth and ability to be cured in situ through a minimally invasive procedure. In this study, we developed a composite hydrogel consisting of photocrosslinkable methacrylated glycol chitosan (MeGC) and semi-interpenetrating collagen (Col) with a riboflavin photoinitiator under blue light. The incorporation of Col in MeGC hydrogels enhanced the compressive modulus and slowed the degradation rate of the hydrogels. MeGC-Col composite hydrogels significantly enhanced cellular attachment, spreading, proliferation and osteogenic differentiation of mouse bone marrow stromal cells (BMSCs) seeded on the hydrogels compared with pure MeGC hydrogels, as observed by upregulated alkaline phosphatase (ALP) activity as well as increased mineralization. Similarly, when cells were encapsulated within hydrogels, BMSCs exhibited greater proliferation, ALP activity and mineral deposits in the presence of Col. These findings demonstrate that MeGC-Col composite hydrogels may be useful in promoting bone regeneration. Copyright © 2014 John Wiley & Sons, Ltd.

BACKGROUND Premature cranial suture fusion may prevent neonatal skull malleability during birth, increasing the risk of unplanned cesarean delivery and neonatal birth trauma caused by cephalopelvic disproportion. We sought to determine the incidence of perinatal maternofetal complications in cases of craniosynostosis. METHODS Records of children presenting with nonsyndromic craniosynostosis to a tertiary pediatric hospital from 1996 to 2012 were reviewed retrospectively with focus on birth history and birth-related complications. RESULTS Six hundred eighteen births were reviewed. Rates of cesarean delivery among mothers of children with craniosynostosis [n = 201 (32.5 percent)] exceeded the overall regional rate of 24.5 percent (OR, 1.50; p < 0.0001). Unplanned cesarean delivery occurred in 19.7 percent of births, and were most associated with nulliparous mothers, breech fetal presentations, and lambdoid or multisuture synostosis patterns. Eleven neonates (1.8 percent) exhibited cranial birth trauma, including cephalohematoma and subgaleal hematoma. Neonates with sagittal or multisuture synostosis patterns were more likely to suffer birth trauma and had a higher mean head circumference than those who did not (81st versus 66th percentile, p < 0.05). CONCLUSIONS In the setting of craniosynostosis, birth trauma is increased-for mothers in the form of increased cesarean delivery risk, and for fetuses in the form of subgaleal and subperiosteal perinatal bleeding. Difficult maternal labor may be mediated especially by multisuture or lambdoid synostosis, whereas fetal birth trauma may be mediated to a greater extent by large head size. Prenatal diagnosis of craniosynostosis could influence decision-making in the management of labor. CLINICAL QUESTION/LEVEL OF EVIDENCE Risk, IV.

We describe an iterative stabilization method that can simultaneously recover camera motion and 3D shape from an image sequence captured under modest deviation from planar motion. This technique iteratively applies a factorization method based on planar motion and can approximate the observed image points to the 2D points projected under planar motion by stabilizing the camera motion. We apply the proposed method to aerial images acquired by a helicopter-borne camera and show better reconstruction of both motion and shape than Christy-Horaud's perspective factorization. Moreover, we confirm that the reprojection errors calculated from the recovered camera motion and 3D shape are very similar to the optimum results yielded by bundle adjustment.

飼料から分離した8種53株のFusarium の培養抽出物について、Salmonella を用いた変異原性試験を実施したところ、5種13株の培養物から強い変異原性を検出した。これらは同一物質と推定されたので、特に強い変異原性を示した菌株について、さらにヒト末梢血リンパ球を用いる染色体異常試験と、マウスを用いる優性致死試験を実施した。その結果、ヒト末梢血リンパ球に対しては染色分体型の異常を誘発し、マウスに対しては後期精子細胞から成熟精子の時期に優性致死を誘発することが確認され、Fusarium 培養物中に含まれる物質はヒトならびに哺乳動物に対して遺伝毒性を誘発する可能性が示唆された。

Polycyclic aromatic hydrocarbons (PAHs) are not easily degradable and exist as persistent contaminants in water environments. In this study we collected surface sediments and water samples from five different ports around Seto Inland Sea during October 2003 to April 2004. Fifteen PAHs were detected by gas chromatography/mass spectrometer (GC-MS). Expression of CYP1A enzymes was measured by a biochemical activation of 7-ethoxy resorufin ortho-deethylase (EROD). Total water PAHs ranged from 2.5ng/l to 132ng/l, while sediment PAHs ranged from 296.3ng/g to 3992.9ng/g, which indicate low to high level of PAH pollution. Selected isomer ratios (fluoranthene/pyrene to phenanthrene/anthracene and, total molecular weight of 202/total molecular weight 202–278), and detected PAHs suggested that the origin of pollution could mostly be pyrogenic. The highest total sediment PAHs were observed at the Uno Port while the lowest were at the New Okayama Port. EROD activity implied that PAH extracted from sediment samples affected on CYP1A enzymes expression on the human hepatocellular carcinoma cell line in a short exposure time (12 hours). Relatively EROD activity showed good correlation between PAH concentration and CYP1A expression for sediment samples. The highest EROD values were observed for sediment samples at a dose of 5ppm. In contrast water samples were at the low induction level even under the highest exposure concentration (50ppm), except in Mizushima Port. Biomonitoring of water environments by EROD activity could be a necessary tool for understanding the effects of PAHs on living organisms at the base of cell defense.

Previous studies showed that long-term hypoxia (LTH) during pregnancy alters myometrial contractility. The present study was designed to test the hypothesis that LTH during pregnancy suppresses myometrial contractility in sheep by affecting the calcium signaling cascade. Pregnant sheep were maintained at high altitude (3820 m) from Day 30 to Day 139 of gestation, when the animals were killed for collection of myometrial tissue. Tissue was also collected from age-matched, normoxic controls. Circular and longitudinal layers were separated, and strips from each layer were mounted in a muscle bath. After pretreatment with 10−8 M oxytocin, the strips were exposed to increasing half- or quarter-log doses of nifedipine (L-type calcium-channel blocker), ruthenium red, ryanodine (blockers of inositol 1,4,5-trisphosphate-insensitive calcium stores), or 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (NCDC; phospholipase C inhibitor). Area under the contraction curve was analyzed, and pD2 (log of concentratio...

An extremely compact, all-permanent-magnet electron cyclotron resonance ion source was designed and manufactured mainly for materials development. The ion source was installed in a 400 kV ion implanter, and a heavy ion beam in the mega-electron-volt (MeV) energy region with high beam intensity was available using multiply charged ions from the ion source. The magnet measured 120 mm in length and 30 mm and 110 mm in inner and outer diameters, respectively. A high magnetic field in the plasma chamber was formed by the unique permanent magnet structure. The maximum and minimum mirror fields achieved were 0.62 and 0.40 T, respectively. Up to 10 W of 13 GHz microwave power was fed to the source by the solid-state microwave generator, and the minimum B structure was formed in the plasma chamber. In the preliminary result at the test stand, an O5+ beam of 11 eμA, an Ar4+ beam of 80 eμA, and a He2+ beam of 100 eμA were available and an Ar12+ beam of 10 eμA was obtained with microwave power of only 10 W. The beam ...

We report on terahertz wireless communication experiments at 0.3 THz using 250-nm gate-length GaAs/AlGaAs field-effect transistor (FET) as a detector and unitraveling-carrier photodiode as a source. The physical mechanism of the detection process is terahertz wave rectification on nonlinearities related to overdamped plasma oscillations in the transistor channel. We present an experimental study of rectification bandwidth and show for the first time that room-temperature direct detection with modulation bandwidth of up to 8 GHz can be achieved, thus showing that nanometer-sized FETs can be used as valuable detectors in all-solid-state terahertz wireless communication systems.

Distributions of structural and refractive index changes of silica irradiated by H + microbeam were studied by optical and atomic force microscopes (AFM). The AFM measurements on the microbeam irradiated area show the formation of a groove on the surface. In addition, a cross sectional observation on the surface parallel to the incident plane reveals surface deformation along the ion tracks, which is deepest at the projected range of ions. Taking into account the possible structural changes of silica induced by energy deposition calculated by TRIM, the measured topological changes at the front and side surfaces result from internal compaction of silica glass. Refractive index changes were estimated from the Lorentz–Lorenz relationship using the distribution of the internal compaction estimated by the AFM measurements.

To study the interactions between the induction of radiation-induced apoptosis and trace elements kinetics, human leukemia cells were irradiated in vitro by 60 Co γ rays, after which the cells were evaluated for the detection of apoptosis and trace element (Fe, Ca, Zn) imaging was carried out. The frequency of apoptosis, i.e. the number of apoptotic bodies per 100 nuclei, was obtained by microscopic assay using TUNEL staining at 400× magnification. The trace element distribution in the cell was determined by micro-PIXE using 2 MeV proton beams. In the early phase of apoptosis, the maximum level of Fe accumulation was observed in the cell stroma. In the mid to end phase, Fe accumulation was diminished, and instead, Ca accumulation increased and Zn decreased in the nucleus. There appear to be two steps for the development of apoptosis: (1) the signaling from cell stroma to nucleus by Fe or an Fe-containing enzyme; and (2) the degeneration of the nucleus by Ca-dependent enzyme, and release of Zn from digested nucleus. Those strong accumulations may be new markers for apoptosis.

We evaluated structural changes in silica glass induced by ion microbeam using microscopic photoluminescence (PL) and Raman scattering measurements. Microbeams (1.7 MeV H+) were scanned over the sharp right-edges of the silica substrates with a fluence of 1×1017 cm−2, then two PL bands of silica at 540 and 650 nm were observed at the irradiated region. The PL bands show different lateral and depth distributions. The distribution of the 540 nm PL is in good agreement with that of the refractive index changed region. The lateral distribution of the 650 nm band is broader by 1.5 times than those of the 540 nm PL and the refractive index changed region. The microscopic Raman scattering measurements show an increased intensity of 606 cm−1 peak associated with compaction at the microbeam irradiated regions.

Weinvestigatethemechanismsofdefectformationandopticalabsorptioninducedbyionimplantation,forfab-rication of optical devices by radiation effects. High-purity silica implanted by H þ or He 2þ was characterized usingvacuum-ultraviolet spectroscopy and electron-spin-resonance measurement. Defect formation is suppressed by OHgroups,possiblybythereleaseofatomichydrogen.TheE 0 centerandnonbridgingoxygenholecenterwerecreatedthroughpairgenerationfromthenormalSiAOASibond.TheperoxyradicalwasgeneratedthroughthereactionoftheE 0 center with interstitial oxygen, which is a Frenkel-defect pair with an oxygen vacancy. By the Kramers–Kroniganalysis on the MeV-ion implantation-induced defects, a refractive index increase of the order of 10 4 was esti-mated. 2002ElsevierScienceB.V.Allrightsreserved. Keywords:Silicaglass;Ionimplantation;Vacuumultraviolet;Electronspinresonance 1. IntroductionFabrication of optical devices such as opticalfibergratingshasbeenreportedbyourgroupus-ing mega-electron-volt-order ion implantation onsilica-coreopticalfibers[1].Inordertoextendthistechniqueforthefabricationofsilica-basedplanaroptical devices, it is important to understand themechanismsbywhichchangesinopticalpropertiessuch as refractive index are induced by the im-plantedions.Attentionisfocusedontheelectronicstopping energy loss, since it accounts for morethan 99% of the total loss and most defects areinducedthroughthisprocessinthecaseofMeV-orderionimplantation.2. Experimental proceduresSamplesaretwotypesofhigh-puritysilicaglas-ses containing different OH contents, EDC (OHcontent