Estimation of Jones matrix, birefringence and entropy using Cloude-Pottier decomposition in polarization-sensitive optical coherence tomography

Estimation of polarimetric parameters has been a fundamental issue to assess biological tissues that have form birefringence or polarization scrambling in polarization-sensitive optical coherence tomography (PS-OCT). We present a mathematical framework to provide a maximum likelihood estimation of the target covariance matrix and its incoherent target decomposition to estimate a Jones matrix of a dominant scattering mechanism, called Cloude-Pottier decomposition, thereby deriving the phase retardation and the optic axis of the sample. In addition, we introduce entropy that shows the randomness of the polarization property. Underestimation of the entropy at a low sampling number is mitigated by asymptotic quasi maximum likelihood estimator. A bias of the entropy from random noises is corrected to show only the polarization property inherent in the sample. The theory is validated with experimental measurements of a glass plate and waveplates, and applied to the imaging of a healthy human eye anterior segment as an image filter.

Real-time imaging of RGC death with a cell-impermeable nucleic acid dyeing compound after optic nerve crush in a murine model

The retinal ganglion cells (RGCs) are the main source of therapeutic targets for neuroprotective glaucoma treatment, and evaluating RGCs is key for effective glaucoma care. Thus, we developed a minimally invasive, quick, real-time method to evaluate RGC death in mice. In this article we describe the details of our method, report new results obtained from C57BL/6J mice, and report that our method was usable in wild type (WT) and knockout (KO) mice lacking an RGC-death-suppressing gene. It used a non-invasive confocal scanning laser ophthalmoscope (cSLO) and a low molecular weight, photo-switching, cell-impermeant, fluorescent nucleic acid dyeing compound, SYTOX orange (SO). The RGCs were retrogradely labeled with Fluorogold (FG), the optic nerve was crushed (ONC), and SO was injected into the vitreous. After ten minutes, RGC death was visualized with cSLO in vivo. The retinas were then extracted and flat mounted for histological observation. SO-labeled RGCs were counted in vivo and FG-labeled RGCs were counted in retinal flat mounts. The time course of RGC death was examined in Calpastatin KO mice and wild type (WT) mice. Our in vivo imaging method revealed that SO-positive dead RGCs were mainly present from 4 to 6 days after ONC, and the peak of RGC death was after 5 days. Moreover, the number of SO-positive dead RGCs after 5 days differed significantly in the Calpastatin KO mice and the WT mice. Counting FG-labeled RGCs in isolated retinas confirmed these results. Thus, real-time imaging with SO was able to quickly quantify ONC-induced RGC death. This technique may aid research into RGC death and the development of new neuroprotective therapies for glaucoma.

Quantification of the filtering bleb's structure with anterior segment optical coherence tomography

BACKGROUND

The aim of the study is to determine the relationship between post-trabeculectomy bleb structure evaluated using anterior segment optical coherence tomography (AS-OCT) and postoperative intraocular pressure (IOP).

DESIGN

Rretrospective is showed for the design of this study.

PARTICIPANTS

There are twenty-seven eyes of 27 trabeculectomy patients.

METHODS

We drew contour lines for the bleb and cleft on 8-radius-scanned AS-OCT images, and determined correlations of AS-OCT measurements to postoperative IOP at 6 months.

MAIN OUTCOME MEASURES

The parameter used in this study is an anterior segment optical coherence tomography measurements of bleb structure, including cleft volume, wall volume, and the brightness of the bleb wall.

RESULTS

We found significant correlations between postoperative IOP at 6 months and cleft volume at 3 and 6 months (r = -0.56, P = 0.007 and r = -0.82, P <0.001), bleb wall volume at 6 months (r = -0.48, P = 0.042), bleb vertical brightness at 3 and 6 months (r = 0.73, P < 0.001 and r = 0.49, P = 0.040), and bleb horizontal brightness at 1 week, 2 weeks, 3 months and 6 months (r = 0.49, P = 0.016, r = 0.65, P < 0.001, r = 0.52, P = 0.013 and r = 0.71, P = 0.001). A stepwise multiple regression analysis of bleb structural measurements made ≤2 weeks postoperatively showed that the strongest independent factor indicating postoperative IOP at 6 months was bleb horizontal brightness at 2 weeks (β = 0.50, P = 0.006).

CONCLUSIONS

Early postoperative AS-OCT measurements of blebs, especially horizontal brightness of the bleb wall, were associated with postoperative IOP at 6 months. AS-OCT measurements of blebs may be useful predictors of trabeculectomy outcomes.

Age- and Sex-Dependency of Laser Speckle Flowgraphy Measurements of Optic Nerve Vessel Microcirculation

Purpose

To investigate the relationship between various characteristics of a normal population and laser speckle flowgraphy (LSFG) measurements of mean blur rate (MBR) in the optic nerve head (ONH).

Methods

A total of 189 eyes of 189 normal subjects (93 male, 96 female, mean age 45 ± 14 years old, age range: 20–72) without any history of hypertension, hyperlipidemia or diabetes were enrolled. ONH microcirculation was measured with LSFG and overall MBR (MA), vessel-area MBR (MV), and tissue-area MBR (MT) were derived from these measurements. The statistical association of these measurements with characteristics such as sex, age, intraocular pressure (IOP) and systolic blood pressure (SBP) was then determined.

Results

There was a trend towards decreased IOP and MV and increased SBP with age (P = 0.002, P = 0.035, and P = 0.006, respectively). Furthermore, IOP, MV and SBP were correlated with age (r = -0.23, P = 0.011; r = -0.24, P < 0.001; and r = 0.30, P < 0.001, respectively). Separate multiple regression analyses of independent contributing factors revealed that sex and IOP contributed to MA (P < 0.001 and P = 0.002, respectively), sex, IOP, and age contributed to MV (P < 0.001, P = 0.003, and P = 0.024, respectively), while only IOP contributed to MT (P = 0.003).

Conclusion

In a normal population, MBR was affected by IOP in both the large vessel and capillary areas of the ONH, but not by SBP. MV was also affected by age and sex, while MT was stable independent of age or sex.

Measurement of the stochastic radial dose distribution for a 30-MeV proton beam using a wall-less tissue-equivalent proportional counter

The frequency distribution of the lineal energy, y, of a 30-MeV proton beam was measured as a function of the radial distance from the beam path, and the dosed mean of y, y¯(D), was obtained to investigate the radial dependence of y¯(D). A wall-less tissue-equivalent proportional counter, in a cylindrical volume with simulated diameters of 0.36, 0.72 and 1.44 µm was used for the measurement of y distributions, yf(y). The measured values of yf(y) summed in the radial direction agreed fairly well with the corresponding data taken from the microdosimetric calculations using the PHITS code. The y¯(D) value of the 30-MeV proton beam presented its smallest value at r = 0.0 and gradually increased with radial distance, and the y¯(D) values of heavy ions such as iron showed rapid decrease with radial distance. This experimental result demonstrated that the stochastic deposited energy distribution of high-energy protons in the microscopic region is rather constant in the core as well as in the penumbra region of the track structure.

Temperature Dependence of Magnetically Active Charge Excitations in Magnetite across the Verwey Transition

We study the electronic structure of bulk single crystals and epitaxial films of Fe_{3}O_{4}. Fe 2p core level spectra show clear differences between hard x-ray (HAX) and soft x-ray photoemission spectroscopy (PES). The bulk-sensitive spectra exhibit temperature (T) dependence across the Verwey transition, which is missing in the surface-sensitive spectra. By using an extended impurity Anderson full-multiplet model-and in contrast to an earlier peak assignment-we show that the two distinct Fe species (A and B site) and the charge modulation at the B site are responsible for the newly found double peaks in the main peak above T_{V} and its T-dependent evolution. The Fe 2p HAXPES spectra show a clear magnetic circular dichroism (MCD) in the metallic phase of magnetized 100-nm-thick films. The model calculations also reproduce the MCD and identify the contributions from magnetically distinct A and B sites. Valence band HAXPES shows a finite density of states at E_{F} for the polaronic half metal with a remnant order above T_{V} and a clear gap formation below T_{V}. The results indicate that the Verwey transition is driven by changes in the strongly correlated and magnetically active B-site electronic states, consistent with resistivity and optical spectra.

Fiber-based polarization-sensitive OCT for birefringence imaging of the anterior eye segment

We demonstrate a prototype system of polarization-sensitive optical coherence tomography (PS-OCT) designed for clinical studies of the anterior eye segment imaging. The system can measure Jones matrices of the sample with depth-multiplexing of two orthogonal incident polarizations and polarization-sensitive detection. An optical clock is generated using a quadrature modulator and a logical circuit to double the clock frequency. Systematic artifacts in measured Jones matrices are theoretically analyzed and numerically compensated using signals at the surface of the sample. Local retardation images of filtering blebs after trabeculectomy show improved visualization of subconjunctival tissue, sclera, and scar tissue of the bleb wall in the anterior eye segment.

Molecular, anatomical and functional changes in the retinal ganglion cells after optic nerve crush in mice

PURPOSE

Optic nerve crush (ONC) and subsequent axonal damage can be used in rodents to study the mechanism of retinal ganglion cell (RGC) degeneration. Here, we examined electroretinograms (ERGs) in post-ONC mice to investigate changes in the positive scotopic threshold response (pSTR). We then compared these changes with molecular and morphological changes to identify early objective biomarkers of RGC dysfunction.

METHODS

Fifty 12-week-old C57BL/6 mice were included. ONC was used to induce axonal injury in the right eye of each animal, with the left eye used as a control. The expression of the RGC markers Brn3a and Brn3b was measured on days 1, 2, 3, 5 and 7 after ONC with quantitative real-time PCR. ERGs were recorded under dark adaptation with the stimulus intensity increasing from -6.2 to 0.43 log cd-s/m(2) on days 1, 2, 3, 5, 7 and 10 after ONC. The pSTR, a- and b-wave amplitudes were measured. Inner retinal thickness around the optic nerve head was measured with spectral-domain optical coherence tomography on days 0, 2, 5, 7 and 10 after ONC.

RESULTS

The expression of Brn3a and Brn3b began to significantly decrease on day 1 and day 2, respectively (P < 0.01). The amplitude of the pSTR underwent rapid, significant deterioration on day 3, after which it fell gradually (P < 0.01), while the a- and b-wave amplitudes remained unchanged throughout the experiment. Inner retinal thickness gradually decreased, with the most significant reduction on day 10 (P < 0.01).

CONCLUSIONS

Decrease in pSTR likely reflected the early loss of RGC function after ONC and that declining expression of RGC-specific genes preceded anatomical and functional changes in the RGCs.

Characteristics and verification of a car-borne survey system for dose rates in air: KURAMA-II

The car-borne survey system KURAMA-II, developed by the Kyoto University Research Reactor Institute, has been used for air dose rate mapping after the Fukushima Dai-ichi Nuclear Power Plant accident. KURAMA-II consists of a CsI(Tl) scintillation detector, a GPS device, and a control device for data processing. The dose rates monitored by KURAMA-II are based on the G(E) function (spectrum-dose conversion operator), which can precisely calculate dose rates from measured pulse-height distribution even if the energy spectrum changes significantly. The characteristics of KURAMA-II have been investigated with particular consideration to the reliability of the calculated G(E) function, dose rate dependence, statistical fluctuation, angular dependence, and energy dependence. The results indicate that 100 units of KURAMA-II systems have acceptable quality for mass monitoring of dose rates in the environment.

Characteristics of uveitic glaucoma and evaluation of its surgical treatment

Purpose

To investigate the characteristics of uveitic glaucoma (UG) and evaluate surgical treatments.

Methods

This study examined a retrospective, nonrandomized comparative interventional case series of 105 UG patients (141 eyes) followed between April 1, 2001 and July 30, 2014 at the outpatient clinic of Tohoku University Hospital. The study group included 47 patients (47 eyes) who underwent glaucoma surgery: trabeculectomy, trabeculotomy, and trabectome surgery. The analysis used Kaplan–Meier life tables, with surgical failure defined as intraocular pressure ≧21 mmHg or the need for additional glaucoma surgery.

Results

UG patients represented 9.73% of our database of glaucoma patients. The mean follow-up period was 40.32±32.53 months. Seventy-one patients had granulomatous uveitis (67.62%) and 34 had nongranulomatous uveitis (32.38%). The causes of uveitis included sarcoidosis (n=25), Behçet’s disease (n=11), Vogt–Koyanagi–Harada disease (n=9), Posner–Schlossman syndrome (n=12), herpes simplex virus infectious uveitis (n=7), acute anterior uveitis (n=5), intermediate uveitis (n=4), scleritis (n=4), inflammatory bowel disease (n=4), varicella zoster virus uveitis (n=2), and others (n=6). An additional 16 patients were diagnosed with idiopathic UG. Surgical success rates were 82.86% for trabeculectomy, 62.50% for trabeculotomy, and 75.00% for trabectome. Significant risk factors for surgical failure included male sex (P=0.02), age less than 45 years (P=0.0009), nongranulomatous uveitis (P=0.04), and postoperative inflammation (P=0.01).

Conclusion

Young male patients with nongranulomatous uveitis had a significant risk of surgical failure. Moreover, prolonged postoperative inflammation created a susceptibility to surgical failure, indicating the importance of postoperative inflammation reduction.

Retinal transcriptome profiling at transcription start sites: a cap analysis of gene expression early after axonal injury

Background

Glaucoma is characterized by progressive loss of the visual field and death of retinal ganglion cells (RGCs), a process that is mediated, in part, by axonal injury. However, the molecular pathomechanisms linking RGC death and axonal injury remain largely unknown. Here, we examined these mechanisms with a cap analysis of gene expression (CAGE), which allows the comprehensive quantification of transcription initiation across the entire genome. We aimed to identify changes in gene expression patterns and to predict the resulting alterations in the protein network in the early phases of axonal injury in mice.

Results

We performed optic nerve crush (ONC) in mice to model axonal injury. Two days after ONC, the retinas were isolated, RNA was extracted, and a CAGE library was constructed and sequenced. CAGE data for ONC eyes and sham-treated eyes was compared, revealing 180 differentially expressed genes. Among them, the Bcat1 gene, involved in the catabolism of branched-chain amino acid transaminase, showed the largest change in expression (log2 fold-change = 6.70). In some differentially expressed genes, alternative transcription start sites were observed in the ONC eyes, highlighting the dynamism of transcription initiation in a state of disease. In silico pathway analysis predicted that ATF4 was the most significant upstream regulator orchestrating pathological processes after ONC. Its downstream candidate targets included Ddit3, which is known to induce cell death under endoplasmic reticulum stress. In addition, a regulatory network comprising IFNG, P38 MAPK, and TP53 was predicted to be involved in the induction of cell death.

Conclusion

Through CAGE, we have identified differentially expressed genes that may account for the link between axonal injury and RGC death. Furthermore, an in silico pathway analysis provided a global view of alterations in the networks of key regulators of biological pathways that presumably take place in ONC. We thus believe that our study serves as a valuable resource to understand the molecular processes that define axonal injury-driven RGC death.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-982) contains supplementary material, which is available to authorized users.

Local current density measurement using a Rogowski probe in Tokyo Spherical Tokamak-2

A Rogowski probe consisting of a small multi-layer Rogowski coil, five magnetic pick-up coils, and a Langmuir probe was developed to measure the local current density and its direction. It can be moved along the major radius and can be turned around its axis. This probe was used to measure the current density profile near the last closed flux surface of Ohmic plasmas in Tokyo Spherical Tokamak-2. The current density profile was measured successfully with a signal to noise ratio of greater than 20.

Demonstration of improvement in the signal-to-noise ratio of Thomson scattering signal obtained by using a multi-pass optical cavity on the Tokyo Spherical Tokamak-2

The multi-pass Thomson scattering (TS) scheme enables obtaining many photons by accumulating multiple TS signals. The signal-to-noise ratio (SNR) depends on the accumulation number. In this study, we performed multi-pass TS measurements for ohmically heated plasmas, and the relationship between SNR and the accumulation number was investigated. As a result, improvement of SNR in this experiment indicated similar tendency to that calculated for the background noise dominant situation.

First Report of Mosaic Disease Caused by Colombian datura virus on Solanum lycopersicum Plants Commercially Cultivated in Japan

In 2009, some commercially grown tomato (Solanum lycopersicum) plants in Chiba Prefecture, Japan, exhibited mosaic symptoms. Ten plants from a total of about 72,000 cultivated plants in the greenhouses showed such symptoms. To identify the causal agent, sap from leaves of the diseased plants was inoculated into Chenopodium quinoa and Nicotiana benthamiana plants. Local necrotic lesions appeared on inoculated leaves of C. quinoa, but no systemic infection was observed. Systemic mosaic symptoms were observed on the N. benthamiana plants inoculated. Single local lesion isolation was performed three times using C. quinoa to obtain a reference isolate for further characterization. N. benthamiana was used for propagation of the isolate. Sap from infected leaves of N. benthamiana was mechanically inoculated into three individual S. lycopersicum cv. Momotaro. Symptoms appearing on inoculated tomatoes were indistinguishable from those of diseased tomato plants found initially in the greenhouse. Flexuous, filamentous particles, ~750 nm long, were observed by electron microscopy in the sap of the tomato plants inoculated with the isolate, indicating that the infecting virus may belong to the family Potyviridae. To determine genomic sequence of the virus, RT-PCR was performed. Total RNA was extracted from the tomato leaves experimentally infected with the isolate using an RNeasy Plant Mini kit (QIAGEN, Hilden, Germany). RT-PCR was performed by using a set of universal, degenerate primers for Potyviruses as previously reported (2). Amplicons (~1,500 bp) generated by RT-PCR were extracted from the gels using the QIAquick Gel Extraction kit (QIAGEN) and cloned into pCR-BluntII TOPO (Invitrogen, San Diego, CA). DNA sequences of three individual clones were determined using a combination of plasmid and virus-specific primers, showing that identity among three clones was 99.8%. A consensus nucleotide sequence of the isolate was deposited in GenBank (AB823816). BLASTn analysis of the nucleotide sequence determined showed 99% identity with a partial sequence in the NIb/coat protein (CP) region of Colombian datura virus (CDV) tobacco isolate (JQ801448). Comparison of the amino acid sequence predicted for the CP with previously reported sequences for CDV (AY621656, AJ237923, EU571230, AM113759, AM113754, and AM113761) showed 97 to 100% identity range. Subsequently, CDV infection in both the original and experimentally inoculated plants was confirmed by RT-PCR using CDV-specific primers (CDVv and CDVvc; [1]), and, hence, the causal agent of the tomato disease observed in greenhouse tomatoes was proved to be CDV. The first case of CDV on tomato was reported in Netherlands (3), indicating that CDV was transmitted by aphids from CDV-infected Brugmansia plants cultivated in the same greenhouse. We carefully investigated whether Brugmansia plants naturally grew around the greenhouses, but we could not find them inside or in proximity to the greenhouses. Therefore, sources of CDV inoculum in Japan are still unclear. This is the first report of a mosaic disease caused by CDV on commercially cultivated S. lycopersicum in Japan. References: (1) D. O. Chellemi et al. Plant Dis. 95:755, 2011. (2) J. Chen et al. Arch. Virol. 146:757, 2001. (3) J. Th. J. Verhoeven et al. Eur. J. Plant. Pathol. 102:895, 1996.

Note: Multi-pass Thomson scattering measurement on the TST-2 spherical tokamak

In multi-pass Thomson scattering (TS) scheme, a laser pulse makes multiple round trips through the plasma, and the effective laser energy is enhanced, and we can increase the signal-to-noise ratio as a result. We have developed a coaxial optical cavity in which a laser pulse is confined, and we performed TS measurements using the coaxial cavity in tokamak plasmas for the first time. In the optical cavity, the laser energy attenuation was approximately 30% in each round trip, and we achieved a photon number gain of about 3 compared with that obtained in the first round trip. In addition, the temperature measurement accuracy was improved by accumulating the first three round trip waveforms.

Pulse-waveform analysis of normal population using laser speckle flowgraphy

PURPOSE

Laser speckle flowgraphy (LSFG), a new, non-invasive method of measuring the mean blur rate (MBR) of ocular blood flow, allows for the analysis of the pulse waveform of a heartbeat as it changes dynamically. Here, we investigated the relationship between the pulse waveform and clinical parameters, particularly age.

MATERIALS AND METHODS

Sixty eyes of 60 healthy subjects without diabetes were enrolled from among patients undergoing annual health examinations. LSFG, and its analysis software, were used to determine pulse waveform parameters including MBR, skew, blowout score (BOS), blowout time (BOT), rising rate and falling rate in the optic nerve head (ONH), both specifically in the tissue area and in the ONH overall. Fifteen clinical parameters were also recorded, including age and blood pressure, as well as triglyceride and creatinine levels.

RESULTS

Skew, BOT and falling rate had a strong correlation (|r| > 0.60) with age, but not with the other clinical parameters. This correlation with age was stronger in the tissue area (BOT: p < 0.0001, r = - 0.68; skew: p < 0.0001, r = 0.65; falling rate: p < 0.0001, r = 0.61) than in the ONH overall (BOT: p < 0.0001, r = -0.67; skew: p < 0.0001, r = 0.60; falling rate: p < 0.0001, r = 0.59). Stepwise multiple regression analysis revealed that tissue area falling rate was an independent factor indicating age, and conversely that age was an independent factor indicating tissue area falling rate.

CONCLUSIONS

The significant correlation of LSFG-measured tissue area falling rate with age suggests that it may be a new candidate biomarker for age-dependent microcirculation.

RNA sequence reveals mouse retinal transcriptome changes early after axonal injury

Glaucoma is an ocular disease characterized by progressive retinal ganglion cell (RGC) death caused by axonal injury. However, the underlying mechanisms involved in RGC death remain unclear. In this study, we investigated changes in the transcriptome profile following axonal injury in mice (C57BL/6) with RNA sequencing (RNA-seq) technology. The experiment group underwent an optic nerve crush (ONC) procedure to induce axonal injury in the right eye, and the control group underwent a sham procedure. Two days later, we extracted the retinas and performed RNA-seq and a pathway analysis. We identified 177 differentially expressed genes with RNA-seq, notably the endoplasmic reticulum (ER) stress-related genes Atf3, Atf4, Atf5, Chac1, Chop, Egr1 and Trb3, which were significantly upregulated. The pathway analysis revealed that ATF4 was the most significant upstream regulator. The antioxidative response-related genes Hmox1 and Srxn1, as well as the immune response-related genes C1qa, C1qb and C1qc, were also significantly upregulated. To our knowledge, this is the first reported RNA-seq investigation of the retinal transcriptome and molecular pathways in the early stages after axonal injury. Our results indicated that ER stress plays a key role under these conditions. Furthermore, the antioxidative defense and immune responses occurred concurrently in the early stages after axonal injury. We believe that our study will lead to a better understanding of and insight into the molecular mechanisms underlying RGC death after axonal injury.

The influence of posture change on ocular blood flow in normal subjects, measured by laser speckle flowgraphy

PURPOSE

To investigate, using laser speckle flowgraphy (LSFG), the autoregulation of ocular blood flow (BF) in response to posture change.

METHODS

This study comprised 20 healthy volunteers (mean age 30.0 ± 8.5). The mean blur rate (MBR) of the ocular circulation in the subjects was assessed in both a sitting and a supine position every 2 min over the course of 10 min. Baseline measurements of the MBR at the optic nerve head (ONH) and the choroid were taken in a sitting position. Increases in the MBR ratio in a supine position were calculated with reference to this baseline. Intraocular pressure (IOP), systemic blood pressure and heart rate in the brachial artery were also recorded.

RESULTS

In the ONH, the MBR ratio increased significantly over the baseline after 2 min (104.8 ± 5.0%, p = 0.001) and 4 min (104.4 ± 5.6%, p = 0.005), in a supine position, but decreased to the initial level after only 6 min. In the choroid, on the other hand, while the MBR ratio also increased significantly after 2 min in a supine position (113.7 ± 8.1%, p < 0.001), it kept this significant increase over the time course of 10 min. After 10 min in a supine position, IOP increased significantly (p < 0.001), systolic blood pressure decreased significantly (p < 0.001), but diastolic blood pressure did not change significantly compared to the baseline. (p = 0.07) CONCLUSIONS: ONH and choroidal circulation have significantly different hemodynamics in response to posture change in healthy volunteers. This finding suggests that LSFG enables us to assess the autoregulation of BF in the ONH.

46 HYPOTHERMIC STORAGE FOR 10 DAYS OF BOVINE EMBRYOS USING TYPE III ANTIFREEZE PROTEIN

Recently, we developed a medium that enabled bovine embryos to be held for up to 7 days at 4°C (Tsuchiya et al. 2014 IETS meeting). To be of practical value, mammalian embryo preservation at hypothermic temperatures must be able to maintain viability for periods longer than 7 days. Antifreeze proteins (AFP) were discovered in various organisms (such as fish, insects, plants, and bacteria) living in cold regions. They show a unique ability to protect cold-sensitive cells from hypothermic damage. Here, we found that a biomolecule known as type III AFP solubilised into an optimized solvent can keep alive bovine embryos for a maximum of 10 days at hypothermic temperatures. First, human hepatoma (HepG2) and rat insulinoma (RIN-5F) cells were stored at 4°C in Euro-Collins solution (Kobayashi Seiyaku, Osaka, Japan) supplemented with or without 10 mg mL–1 of type III AFP for 24 h. The viability rate of the cells was assessed by trypan blue (Dojindo, Kumamoto, Japan) dissolved in PBS. Second, high-quality blastocysts produced in vivo were stored at 4°C in a plastic ministraw in 25 mM HEPES medium 199 plus 20% fetal bovine serum (FBS) supplemented with or without 10 mg mL–1 of type III AFP for 10 days. Following hypothermic preservation, the chilled embryos were squeezed out of the straw into PBS and washed 3 times in the same medium. Subsequently, the embryos were cultured in CR1aa medium supplemented with 5% FBS for 48 h at 38.5°C under 5% CO2 in air with high humidity. The viability and hatching rate of the embryos were assessed at the end of the culture period. Finally, 4 embryos stored for 10 days with type III AFP were reloaded into plastic straws with the washing medium and transferred into recipient heifers (1 embryo per recipient). Pregnancy was determined by real-time B-mode ultrasonography (Convex scanner HS-1500, Honda Electronics Co. Ltd., Toyohashi, Japan) on Day 60 of gestation. Data were analysed using chi-squared and Student's t-tests. In the absence of type III AFP, the cell viability values of HepG2 and RIN-5F after hypothermic storage for 24 h were only 5 and 22%, respectively. However, in the presence of type III AFP, the cell viability values were dramatically increased (HepG2: 71%; RIN-5F: 59%) than those measured without type III AFP. To examine the effect of type III AFP for hypothermic preservation of bovine embryos, we used 80 high-quality embryos produced in vivo and assigned them randomly to 2 experimental groups. The viability and hatching rates of the chilled embryos stored with type III AFP for 10 days were significantly higher (58 and 30%, respectively) than those of without type III AFP (28 and 0%, respectively). The pregnancy rate of the chilled embryos stored with type III AFP was 50%: 2 pregnancies continue until now. In conclusion, prolongation of short-term preservation period with AFP-containing fluid will realise LN2-free storage of bovine embryos for a 10-day period. This work was supported by the Program for Promotion of Basic and Applied Research for Innovations in Bio-Oriented Industry.

51 ARTIFICIAL DORMANCY OF BOVINE EMBRYOS FOR A MAXIMUM OF 7 DAYS USING A SIMPLE MEDIUM

The worldwide pregnancy rate using cryopreserved mammalian embryos has not improved over the past 2 decades, probably because the freeze-thawing processes cause significant damage. Therefore, it is now relevant to examine the feasibility of short-term non-freezing preservation, and whether this could be applied to embryos that have high vitality and are to be transferred into recipients within several days. We introduce here an artificial dormancy fluid that can extend the hypothermic storage period of bovine embryos for a maximum of 7 days. First, to examine the effect of different basal media and the optimal concentration of fetal bovine serum (FBS) for hypothermic preservation, bovine blastocysts produced in vitro were stored at 4°C in a plastic ministraw in 1 of the following 3 media: PBS, medium 199, or Leibovitz L15 with various amount of FBS (0, 5, 20, 50, or 100%) for 3 days. Second, to examine the effect of Good's buffers, bovine embryos produced in vivo (morula to blastocyst stages) were stored at 4°C in a plastic ministraw in medium 199 plus 50% FBS supplemented with various Good's buffers [HEPES, TES, piperazine-N,N′-bis(2-ethanesulfonic acid) (PIPES), MOPS, and 4-(2-hydroxyethyl)piperazine-1-propanesulfonic acid (EPPS)] for 7 days. Following hypothermic preservation, the chilled embryos were squeezed out of the straw into PBS and washed 3 times in the same medium. Subsequently, the embryos were cultured in CR1aa medium supplemented with 5% FBS for 48 h at 38.5°C under 5% CO2 in air with high humidity. The viability rate of the embryos was assessed at the end of the culture period. Finally, to observe the pregnancy rate of chilled embryos, 32 embryos produced in vivo were stored at 4°C for 7 days in medium 199 plus 50% FBS supplemented with HEPES. Following hypothermic preservation, the chilled embryos were transferred into recipient heifers (1 embryo per recipient). Pregnancy was determined by real-time B-mode ultrasonography (Convex scanner HS-1500, Honda electronics Co. Ltd, Toyohashi, Japan) on Day 60 of gestation. Data were analysed using the chi-squared test. The viability rate of the embryos after hypothermic storage for 3 days was significantly increased for medium 199 plus 50% FBS [27/30 (90%)] compared with PBS [18/30 (60%)] or Leibovitz L15 [15/30 (50%)] plus 50% FBS (P < 0.05). Chilled embryos stored for 7 days in medium 199 plus 50% FBS supplemented with HEPES had much higher survival than embryos stored in the same medium with other Good's buffers. The pregnancy rate of the chilled embryos stored for 7 days was extremely high [24/32 (75%)] and normal live calves were delivered at term. In conclusion, maintaining artificial dormancy of bovine embryos for 7 days using a simple medium appears to be feasible. This is the first documented success of storing chilled mammalian embryos in a viable state for 7 days. To be of practical value, bovine embryo preservation at hypothermic temperatures must be able to maintain viability for periods longer than 7 days. This work was supported by the Program for Promotion of Basic and Applied Research for Innovations in Bio-Oriented Industry.