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1

Selective single blastocyst transfer study: 604 cases in 6 years  

PubMed Central

AIM: To evaluate the credibility of single blastocyst transfer (SBT) method in selected group of patients. SETTINGS AND DESIGN: Retrospective analysis of SBT cases based on computerized data in a private Fertility research centre. MATERIALS AND METHODS: A total of 604 cases of SBTs, done during June 2000 to June 2006, have been analyzed retrospectively to assess the credibility of the method as a method of choice in selective high fertile group of patients. Women between 28 and 42 years have been included in the retrospective analysis, who had adequate number of eggs for fertilization, between 6 and 12. RESULTS AND CONCLUSIONS: Grade I blastocyst transfer resulted in 46.6% of clinical pregnancy and grade II blastocyst transfer resulted in 17.4% of clinical pregnancy rates. Overall pregnancy rate was 64%. Pregnancy loss, as early and late fetal wastages, was 11.06%.

Sadasivam, Nirmala; Sadasivam, Narayanan M.

2008-01-01

2

Clinical outcome of frozen blastocyst transfer; single vs. double transfer  

Microsoft Academic Search

Purpose  Frozen embryo transfer has been established as an indispensable ART procedure for both the effective use of surplus embryos\\u000a and the prevention of ovarian hyperstimulation syndrome. The frequency of frozen embryo transfer is increasing in our clinic,\\u000a and we report that frozen embryo transfer is effective for patients with repeat failures. We present our clinical outcome\\u000a of frozen blastocyst transfer

Atsushi Yanaihara; Takeshi Yorimitsu; Hiroshi Motoyama; Motohiro Ohara; Toshihiro Kawamura

2008-01-01

3

Frozen-thawed embryo transfer cycles: clinical outcomes of single and double blastocyst transfers  

Microsoft Academic Search

Purpose  To evaluate clinical outcomes of frozen-thawed embryo transfer cycles when one or two blastocysts are transferred.\\u000a \\u000a \\u000a \\u000a Methods  Retrospective chart review\\u000a \\u000a \\u000a \\u000a Results  Two hundred forty-three frozen blastocyst transfer (FBT) cycles were analyzed. Clinical pregnancy rate (50.4% vs. 34.7%),\\u000a live birth rate (45.8% vs. 30.6%), and twin live birth rate (19.3% vs. 0) were significantly higher in the double versus single\\u000a FBT group, respectively

Inna Berin; Sarah T. McLellan; Eric A. Macklin; Thomas L. Toth; Diane L. Wright

4

Early pregnancy loss is significantly higher after day 3 single embryo transfer than after day 5 single blastocyst transfer in GnRH antagonist stimulated IVF cycles  

Microsoft Academic Search

The current study aimed to investigate whether single day-3 embryo transfer (SET) results in higher early pregnancy loss (EPL) than single blastocyst transfer (SBET). A total of 896 patients underwent 1103 IVF cycles with a gonadotrophin-releasing hormone (GnRH) antagonist protocol. In 603 cycles (D3 group) a single embryo on day 3 of the embryo culture was transferred, whereas in the

EG Papanikolaou; M Camus; HM Fatemi; H Tournaye; G Verheyen; Andre Van Steirteghem; Paul Devroey

2006-01-01

5

Comparison of elective single cleavage-embryo transfer to elective single blastocyst-embryo transfer in human IVF-ET  

PubMed Central

Objective This study was carried out to compare the clinical outcome of elective single cleavage-embryo transfer (eSCET) to that of elective single blastocyst-embryo transfer (eSBET) in human IVF-ET. Methods This study was a retrospective study which analyzed for 614 women who visited the Daegu Maria Clinic from August 2008 to December 2009. All were under 37 years old and had more than 8 mm of endometrial thickness on the day of hCG administration and at least one good quality embryo on day 3. The eSCETs were performed on day 3 (n=450) and the eSBETs were conducted on day 5 (n=164). Results The numbers of retrieved oocytes, fertilized oocytes, and day 3 good quality embryos were significantly lower in the eSCET group (12.1±6.0, 8.2±4.6, and 4.2±3.1, respectively) compared to the eSBET group (16.7±7.2, 12.1±5.0, and 8.5±4.5, respectively; p<0.001). However, the clinical pregnancy, implantation, on-going pregnancy, and live birth rates of the eSCET group (46.7, 46.9, 40.0, and 36.7%, respectively) were not statistically different from those of the eSBET group (51.2, 51.8, 45.1, and 43.9%, respectively; p=0.318, 0.278, 0.254, and 0.103, respectively). Conclusion These results suggested that elective single embryo transfer should be performed regardless of the developmental stage to women less than 37 years old who had more than 8 mm of endometrial thickness on the hCG administration day and at least one good quality embryo on day 3 in order to reduce the twin pregnancy rate without reducing the whole pregnancy rate.

Kang, Sang Min; Lee, Sang Won; Jeong, Hak Jun; Yoon, San Hyun; Lim, Jin Ho

2011-01-01

6

Should a single blastocyst transfer policy be a clinical decision or should it depend on the embryological evaluation on day 3?  

Microsoft Academic Search

Background  Single blastocyst transfer has the advantage of maximizing the fresh single pregnancy rate. However, in patients with a low\\u000a number of good quality embryos on day 3, it remains unclear whether immediate embryo transfer or further embryo culture with\\u000a blastocyst transfer is the most preferable option.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A retrospective cohort study was carried out in which the outcome of 590 fresh

Dominic Stoop; Lisbet Van Landuyt; Etienne Van den Abbeel; Michel Camus; Greta Verheyen; Paul Devroey

2011-01-01

7

Overnight incubation improves selection of frozen–thawed blastocysts for transfer: preliminary study using supernumerary embryos  

Microsoft Academic Search

A study was undertaken to determine whether the interval between thawing and transfer influences both biological and clinical outcomes of cryopreserved blastocysts, using supernumerary embryos cultured in sequential media. One hundred and seventy-two patients who underwent blastocyst thawing without any exclusion criteria were included in this single center prospective study of blastocyst thawing cycles. Outcome of 338 blastocysts originating from

Fabrice Guerif; Veronique Cadoret; Josette Poindron; Jacques Lansac; Dominique Royere

2003-01-01

8

Selection of single blastocysts for fresh transfer via standard morphology assessment alone and with array CGH for good prognosis IVF patients: results from a randomized pilot study  

PubMed Central

Background Single embryo transfer (SET) remains underutilized as a strategy to reduce multiple gestation risk in IVF, and its overall lower pregnancy rate underscores the need for improved techniques to select one embryo for fresh transfer. This study explored use of comprehensive chromosomal screening by array CGH (aCGH) to provide this advantage and improve pregnancy rate from SET. Methods First-time IVF patients with a good prognosis (age <35, no prior miscarriage) and normal karyotype seeking elective SET were prospectively randomized into two groups: In Group A, embryos were selected on the basis of morphology and comprehensive chromosomal screening via aCGH (from d5 trophectoderm biopsy) while Group B embryos were assessed by morphology only. All patients had a single fresh blastocyst transferred on d6. Laboratory parameters and clinical pregnancy rates were compared between the two groups. Results For patients in Group A (n?=?55), 425 blastocysts were biopsied and analyzed via aCGH (7.7 blastocysts/patient). Aneuploidy was detected in 191/425 (44.9%) of blastocysts in this group. For patients in Group B (n?=?48), 389 blastocysts were microscopically examined (8.1 blastocysts/patient). Clinical pregnancy rate was significantly higher in the morphology?+?aCGH group compared to the morphology-only group (70.9 and 45.8%, respectively; p?=?0.017); ongoing pregnancy rate for Groups A and B were 69.1 vs. 41.7%, respectively (p?=?0.009). There were no twin pregnancies. Conclusion Although aCGH followed by frozen embryo transfer has been used to screen at risk embryos (e.g., known parental chromosomal translocation or history of recurrent pregnancy loss), this is the first description of aCGH fully integrated with a clinical IVF program to select single blastocysts for fresh SET in good prognosis patients. The observed aneuploidy rate (44.9%) among biopsied blastocysts highlights the inherent imprecision of SET when conventional morphology is used alone. Embryos randomized to the aCGH group implanted with greater efficiency, resulted in clinical pregnancy more often, and yielded a lower miscarriage rate than those selected without aCGH. Additional studies are needed to verify our pilot data and confirm a role for on-site, rapid aCGH for IVF patients contemplating fresh SET.

2012-01-01

9

Transfers of fresh blastocysts and blastocysts cultured from thawed cleavage embryos are associated with fewer miscarriages  

Microsoft Academic Search

The literature shows an inconsistent relationship between miscarriage and assisted reproduction treatment factors. This study assessed the association between miscarriage and transfer of fresh or thawed embryos at cleavage\\/blastocyst stages. A population study included 52,874 pregnancies following autologous cycles. The miscarriage rate was compared by groups of transferred embryos (fresh cleavage embryo, fresh blastocyst, thawed cleavage embryo, blastocyst from thawed

Yueping Alex Wang; Michael Costello; Michael Chapman; Deborah Black; Elizabeth Anne Sullivan

10

Transfer of spontaneously hatching or hatched blastocyst yields better pregnancy rates than expanded blastocyst transfer  

PubMed Central

CONTEXT: Blastocyst stage embryo transfer (ET) has become routine practice in recent years. However, probably due to limitations of assisted hatching techniques, expanded blastocyst transfer (EBT) is still the preferred mode. Inexplicably, not much consideration has been given to spontaneously hatching/hatched blastocyst transfer (SHBT). AIM: This study aimed to investigate developmental potential of spontaneously hatching/hatched blastocyst against EBT in in vitro fertilization (IVF) cycles. SETTINGS AND DESIGN: Prospective study of 146 women undergoing their first IVF- ET cycle. SUBJECTS AND METHODS: On the basis of blastocyst status, women were classified into SHBT and EBT groups. Intracytoplasmic sperm injection cycles were excluded to remove male factor bias. Implantation rate (IR), clinical pregnancy rate, and live birth rate were the main outcome measures. STATISTICAL ANALYSIS: Graph-pad Prism 5 statistical package. RESULTS: SHBT group showed significantly higher blastocyst formation rate (53.3 ± 17.5 vs. 43.1 ± 14.5%, P = 0.0098), top-quality blastocysts (71.8 vs. 53.7%, P = 0.0436), IR (43.6 vs. 27.9%, P = 0.0408), pregnancy rate (59.4 vs. 45.1%, P = 0.0173), and live birth rate (36.8 vs. 22.8%, P = 0.003) compared to EBT group. Multiple pregnancy rates remained comparable between the two groups. Implantation correlated strongly with top-quality blastocysts (Pearson, r = 0.4441) in SHBT group, while the correlation was nonsignificant in EBT group. CONCLUSION: Extending culture of expanded blastocysts by a few hours to allow transfer of spontaneously hatching/hatched blastocysts gives higher implantation and pregnancy rates with no added risk of multiple gestations. Spontaneously hatching/hatched blastocysts have a better potential to implant and develop into a positive pregnancy.

Chimote, Natachandra M.; Chimote, Nishad N.; Nath, Nirmalendu M.; Mehta, Bindu N.

2013-01-01

11

Pregnancy outcome after blastocyst transfer as compared to early cleavage stage embryo transfer  

Microsoft Academic Search

BACKGROUND: Retrospective cohort study to evaluate differences in outcome when embryo transfer was per- formed either on day 2- 3 (cleavage stage, CS-group) or on day 4- 5 (blastocyst stage, BS-group). METHODS: A total of 1259 consecutive cycles yielding 500 live born babies performed at a single centre in Bregenz, Austria, were included. Main outcome measures were implantation and (multiple)

Peter Schwarzler; Herbert Zech; Margherita Auer; Karin Pfau; Georg Gobel; Pierre Vanderzwalmen; Nicolas Zech

2004-01-01

12

Improved methods for blastocyst formation and culture  

Microsoft Academic Search

Transfer at the blastocyst stage has been proposed to increase the pregnancy rates after in-vitro fertilization (IVF) and embryo transfer. In the first period of experiments, culture in a single medium, from fertilization to blastocyst led to disapointing results: low blastocyst formation rates and low implanta- tion rates per blastocyst transferred. Then the period of co-culture began (starting with animals

Yves Menezo; Anna Veiga; Moncef Benkhalifa

1998-01-01

13

High implantation and pregnancy rates with transfer of human blastocysts developed in preimplantation stage one and blastocyst media  

Microsoft Academic Search

Objective: To evaluate the proficiency of preimplantation stage one (P1) and blastocyst media in supporting human blastocyst development and to document implantation and clinical pregnancy rates from the transfer of the normally developed blastocysts.Design: Retrospective clinical study.Setting: Private IVF unit of a university-affiliated center.Patient(s): Twenty-eight women aged 33.7 ± 2.9 years who underwent IVF treatment for infertility.Intervention(s): Bipronucleate oocytes obtained

Eduardo Leme Alves da Motta; José Roberto Alegretti; Edmundo C Baracat; David Olive; Paulo C Serafini

1998-01-01

14

Comparison of clinical outcomes following vitrified warmed day 5/6 blastocyst transfers using solid surface methodology with fresh blastocyst transfers  

PubMed Central

OBJECTIVES: The literature regarding clinical outcomes following day 5/6 vitrified warmed blastocysts transfer has been conflicting. We decided to evaluate and compare the clinical outcomes following vitrified warmed day 5/6 blastocyst transfer using a solid surface vitrification protocol with fresh blastocyst transfers. SETTINGS: University teaching hospital. STUDY DESIGN: A total of 249 women were retrospectively analyzed: 146 fresh day 5 blastocyst (group 1), 57 day 5 vitrified warmed blastocyst (group 2), and 46 vitrified warmed day 6 blastocyst (group 3) transfer cycles. Vitrification was done using solid surface methodology (non immersion protocol). The main outcomes were implantation rates, clinical pregnancy, and live birth rate per embryo transfer. RESULTS: The baseline clinical characteristics were similar among all three groups. The implantation and clinical pregnancy rates following vitrified warmed day 6 blastocyst transfers (20.9% and 32.6%) were significantly lower as compared to day 5 fresh and vitrified warmed day 5 blastocyst transfers (40.3% and 56.1%, 36.3%, and 52.6%). However, there was no significant difference in the live birth rates across the three groups (group 1: 37.6%, group 2: 40.3%, and group 3: 28.2%). CONCLUSION: No statistically significant difference was observed in live birth rates between fresh day 5 blastocyst transfers and vitrified warmed day 5/6 blastocyst transfers. Vitrification of blastocysts using solid surface methodology is an efficient method of cryopreservation.

Muthukumar, K; Kamath, Mohan S; Mangalaraj, Ann M; Aleyamma, TK; Chandy, Achamma; George, Korula

2013-01-01

15

A prospective trial of blastocyst culture and transfer  

Microsoft Academic Search

BACKGROUND: The aim of this study was to evaluate the effectiveness of the blastocyst culture method compared with the conventional day 3 transfer method using a prospective trial. METHODS: A total of 235 patients with 273 cycles were evaluated for a period of almost 1 year. Depending upon the sequence in which the ovum retrieval was performed, patients were prospectively

Takafumi Utsunomiya; Tae Naitou; Miyuki Nagaki

16

Rescuing human embryonic stem cell research: the Blastocyst Transfer Method.  

PubMed

Despite the therapeutic potential of human embryonic stem (HES) cells, many people believe that HES cell research should be banned. The reason is that the present method of extracting HES cells involves the destruction of the embryo, which for many is the beginning of a person. This paper examines a number of compromise solutions such as parthenogenesis, the use of defective embryos, genetically creating a "pseudo embryo" that can never form a placenta, and determining embryo death, and argues that none of these proposals are likely to satisfy embryoists, that is, those who regard the embryo as a person. This paper then proposes a method of extracting HES cells, what might be called the Blastocyst Transfer Method, that meets the ethical requirements of embryoists, and it considers some possible concerns regarding this method. It concludes by encouraging future HES cell research to investigate this method. PMID:16282102

Liao, S Matthew

2005-01-01

17

Live Birth from Previously Vitrified Oocytes, After Trophectoderm Biopsy, Revitrification, and Transfer of a Euploid Blastocyst  

PubMed Central

Our objective is to describe a successful live birth from oocyte vitrification followed by thaw, fertilization, blastocyst culture, trophectoderm biopsy, vitrification, and subsequent thaw. Fifteen mature oocytes were frozen from a patient with uterine factor infertility. Thirteen oocytes survived the thaw, and five underwent trophectoderm biopsy and were refrozen. Three euploid embryos were obtained. A single euploid embryo was transferred in the second thaw cycle to a known recipient leading to the delivery of a normal male infant. This case report is proof of the concept that preimplantation screening and diagnosis is an option for fertility preservation patients.

Grifo, Jamie A.; Hodes-Wertz, Brooke; Lee, Hsiao Ling; Ampeloquio, Esmeralda; Clarke-Williams, Melicia; Adler, Alexis; Munne, Santiago; Berkeley, Alan S.

2013-01-01

18

Sequential transfer of day 3 embryos and blastocysts after previous IVF failures despite adequate ovarian response  

Microsoft Academic Search

The purpose of this study was to compare IVF outcome following sequential embryo transfer (ET) with that following the transfer of early cleavage embryos among patients with previous multiple IVF failures but adequate ovarian response. A retrospective matched case–control analysis was made of the medical files of 66 women who underwent sequential transfer of day 3 embryos and blastocysts in

Ronit Machtinger; Jehoshua Dor; Matbeii Margolin; Jacob Levron; Micha Baum; Betty Ferber; Adrian Shulman; David Bider; Daniel S Seidman

2006-01-01

19

Transfer of nonassisted hatched and hatching human blastocysts after in vitro fertilization  

Microsoft Academic Search

Objective:To determine the feasibility of performing blastocyst transfer 6 days after oocyte insemination.Design: Retrospective clinical study.Setting: University-based IVF center.Patient(s): All cases of IVF over a 1-year span of time (June 1998–1999) in which seven 2PN embryos were available for transfer.Intervention(s): None.Main Outcome Measure(s): Implantation, pregnancy, and multiple pregnancy rates.Result(s): Transfer of blastocysts on days 5 and 6 resulted in implantation

Omid Khorram; Sander S Shapiro; Jeffrey M Jones

2000-01-01

20

Clinical outcome of fresh and vitrified-warmed blastocyst and cleavage-stage embryo transfers in ethnic Chinese ART patients  

PubMed Central

Objectives This study sought to evaluate the outcome of fresh and vitrified-warmed cleavage-stage and blastocyst-stage embryo transfers in patients undergoing ART treatment within an ethnic Chinese population. Study design We compared the clinical results of embryo transfer on the 3rd (cleavage stage) or 5th (blastocyst stage) day after oocyte retrieval, including clinical pregnancy rates, implantation rates and multiple pregnancy rates. Results Our data showed that blastocyst transfer on day 5 did not significantly increase clinical pregnancy rate (41.07% vs 47.08%, p>0.05) and implantation rate (31.8% vs 31.2%, p>0.05) in patients under 35 years of age, in comparison with day 3 cleavage stage embryo transfer. In patients older than 35 years of age, the clinical pregnancy rate after blastocyst transfer was slightly decreased compared with cleavage stage embryo transfer (33.33% vs 42.31%, p>0.05). Unexpectedly, It was found that vitrified-warmed blastocyst transfer resulted in significantly higher clinical pregnancy rate (56.8%) and implantation rate (47%) compared with fresh blastocyst transfer in controlled stimulation cycles (41.07% and 31.8%, respectively). For patients under 35 years of age, the cumulative clinical pregnancy rate combining fresh and vitrified-warmed blastocyst transfer cycles were significantly higher compared to just cleavage-stage embryo transfer (70.1% versus 51.8%, p<0.05). However, the cumulative multiple pregnancy rates showed no significant difference between the two groups. Conclusions In an ethnic Chinese patient population, fresh blastocyst transfer does not significantly increase clinical pregnancy rate. However, subsequent vitrified-warmed blastocyst transfer in a non-controlled ovarian hyperstimulation cycle dramatically improves clinical outcomes. Therefore, blastocyst culture in tandem with vitrified-warmed blastocyst transfer is recommended as a favourable and promising protocol in human ART treatment, particularly for ethnic Chinese patients.

2012-01-01

21

A prospective randomized trial of blastocyst culture and transfer in in-vitro fertilization  

Microsoft Academic Search

The effectiveness of blastocyst culture and transfer in human in-vitro fertilization (IVF) was evaluated in a prospective randomized trial in patients having a moderate to good response to gonadotrophin stimulation. Embryos were transferred either on day 3 after culture to around the 8-cell stage in Ham's F-10 medium supplemented with fetal cord serum, or on day 5 after culture to

David K. Gardner; William B. Schoolcraft; Lyla Wagley; Terry Schlenker; John Stevens; John Hesla

1999-01-01

22

Uncoupled Embryonic and ExtraEmbryonic Tissues Compromise Blastocyst Development after Somatic Cell Nuclear Transfer  

Microsoft Academic Search

Somatic cell nuclear transfer (SCNT) is the most efficient cell reprogramming technique available, especially when working with bovine species. Although SCNT blastocysts performed equally well or better than controls in the weeks following embryo transfer at Day 7, elongation and gastrulation defects were observed prior to implantation. To understand the developmental implications of embryonic\\/extra-embryonic interactions, the morphological and molecular features

Séverine A. Degrelle; Florence Jaffrezic; Evelyne Campion; Kim-Anh Lê Cao; Daniel Le Bourhis; Christophe Richard; Nathalie Rodde; Renaud Fleurot; Robin E. Everts; Jérôme Lecardonnel; Yvan Heyman; Xavier Vignon; Xiangzhong Yang; Xiuchun C. Tian; Harris A. Lewin; Jean-Paul Renard; Isabelle Hue

2012-01-01

23

Factors affecting the outcome of human blastocyst vitrification  

Microsoft Academic Search

With single blastocyst transfer practice becoming more common in ART, there is a greater demand for a convenient and reliable cryostorage of surplus blastocysts. Vitrification has emerged in the last decade as an alternative promising substitute for slow freezing. Blastocysts represent a unique challenge in cryostorage due to their size, multicellular structure and presence of blastocoele. The continuous acquisition of

Amr A Kader; Audrey Choi; Yasser Orief; Ashok Agarwal

2009-01-01

24

Blastocyst culture and transfer: analysis of results and parameters affecting outcome in two in vitro fertilization programs  

Microsoft Academic Search

Objective: To determine whether previously described advanced blastocyst development and high implantation rates are confirmed in an expanded multicenter trial.Design: Retrospective review.Setting: Two private assisted reproductive technology units.Patient(s): One hundred seventy-four patients who underwent blastocyst culture and transfer.Intervention(s): Culture of all pronucleate embryos in sequential media to the blastocyst stage (day 5) followed by ET.Main Outcome Measure(s): The number and

William B Schoolcraft; David K Gardner; Terry Schlenker; David R Meldrum

1999-01-01

25

Endometrial thickness, Caucasian ethnicity, and age predict clinical pregnancy following fresh blastocyst embryo transfer: a retrospective cohort  

Microsoft Academic Search

BACKGROUND: In-vitro fertilization (IVF) with blastocyst as opposed to cleavage stage embryos has been advocated to improve success rates. Limited information exists on which to predict which patients undergoing blastocyst embryo transfer (BET) will achieve pregnancy. This study's objective was to evaluate the predictive value of patient and cycle characteristics for clinical pregnancy following fresh BET. METHODS: This was a

Michael L Traub; Anne Van Arsdale; Lubna Pal; Sangita Jindal; Nanette Santoro

2009-01-01

26

Sex ratio and birth weights of infants born as a result of blastocyst transfers compared with early cleavage stage embryo transfers  

Microsoft Academic Search

Objective: To analyze the birth weights and sex ratio of infants born as a result of blastocyst transfer and compare them with data resulting from the transfer of early-cleavage stage embryos.Design: Retrospective analysis.Setting: Monash IVF (private in vitro fertilization clinic).Patient(s): One hundred twenty-five infertile patients who became pregnant after IVF procedures involving blastocyst transfer.Intervention(s): None.Main Outcome Measure(s): Sex ratio and

Annette Kausche; Gayle M Jones; Alan O Trounson; Fatima Figueiredo; Vivien MacLachlan; Nick Lolatgis

2001-01-01

27

To blastocyst or not to blastocyst? That is the question.  

PubMed

Recent advances in culture media preparations have allowed for cleavage embryos to be developed to the blastocyst stage. Blastocysts are regarded as having increased implantation potential, and two blastocysts are typically transferred, which reduces the occurrence of high order multiple gestations. However, with current techniques, most cleavage embryos do not become blastocysts and it is not clear how many of these embryos would have implanted had they been replaced at the cleavage stage. Furthermore, experience with blastocyst cryopreservation is lacking and the overall benefit of blastocyst culture is unknown, unless we consider the combined pregnancy rates of both fresh and frozen blastocysts. PMID:11278206

Alper, M M; Brinsden, P; Fischer, R; Wikland, M

2001-04-01

28

The study of developmental capacity of vitrified mouse blastocysts in different straws after transfer to mouse pseudo pregnant.  

PubMed

Vitrification is the commonly used method for long-term storage of pre-implantation mammalian embryos. It is an essential part of assisted reproductive technologies. The re-expansion rate, pregnancy and birth rate of vitrified blastocysts using CPS were compared with OPS and Conventional Straw. Female NMRI mice were injected with Gonadotrophins in order induce them for super ovulation. At that time the mice were sacrified by cervical dislocation and dissected of mouse abdomen. The uterine horns were existed blastocysts were collected in PBS and randomly allocated to four groups: vitrification in CPS, conventional straw, OPS and untreated controls. The vitrification solution was EFS40%. After storage for 1 month in liquid nitrogen, the blastocysts were thawed in 0.5 M sucrose for in vitro culture in M16 medium. After 6 h of culture, the numbers of expanded blastocysts was recorded and ready for transfer to uterus of pseudo pregnant mouse. The re-expansion rate of the CPS group (72.1%) was significantly higher (p < 0.05) than OPS (52.55) and C.S. (38.6%) groups. The pregnancy (70%) and birth rate (45%) of blastocysts in CPS were similar to those of fresh blastocysts (80% and 45.5%) and the pregnancy (10%) and birth rate (5.1%) in Conventional Straws lower than OPS (20 and 7.5%), but were not significantly different. Mouse blastocysts vitrified using CPS had a better result compared with OPS and Conventional Straw. The value of CPS for vitrification of blastocysts may also merit investigation. PMID:18817221

Saki, Ghasem; Rahim, Fakher; Moradi, Lida

2008-07-15

29

Analysis of embryo morphokinetics, multinucleation and cleavage anomalies using continuous time-lapse monitoring in blastocyst transfer cycles  

PubMed Central

Background Time-lapse imaging combined with embryo morphokinetics may offer a non-invasive means for improving embryo selection. Data from clinics worldwide are necessary to compare and ultimately develop embryo classifications models using kinetic data. The primary objective of this study was to determine if there were kinetic differences between embryos with limited potential and those more often associated with in vitro blastocyst formation and/or implantation. We also wanted to compare putative kinetic markers for embryo selection as proposed by other laboratories to what we were observing in our own laboratory setting. Methods Kinetic data and cycle outcomes were retrospectively analyzed in patients age 39 and younger with 7 or more zygotes cultured in the Embryoscope. Timing of specific events from the point of insemination were determined using time-lapse (TL) imaging. The following kinetic markers were assessed: time to syngamy (tPNf), t2, time to two cells (c), 3c (t3), 4c ( t4), 5c (t5), 8c (t8), morula (tMor), start of blastulation (tSB); tBL, blastocyst (tBL); expanded blastocyst (tEBL). Durations of the second (cc2) and third (cc3) cell cycles, the t5-t2 interval as well as time to complete synchronous divisions s1, s2 and s3 were calculated. Incidence and impact on development of nuclear and cleavage anomalies were also assessed. Results A total of 648 embryos transferred on day 5 were analyzed. The clinical pregnancy and implantation rate were 72% and 50%, respectively. Morphokinetic data showed that tPNf, t2,t4, t8, s1, s2,s3 and cc2 were significantly different in embryos forming blastocysts (ET or frozen) versus those with limited potential either failing to blastulate or else forming poor quality blastocysts ,ultimately discarded. Comparison of embryo kinetics in cycles with all embryos implanting (KID+) versus no implantation (KID-) suggested that markers of embryo competence to implant may be different from ability to form a blastocyst. The incidence of multinucleation and reverse cleavage amongst the embryos observed was 25% and 7%, respectively. Over 40% of embryos exhibiting these characteristics did however form blastocysts meeting our criteria for freezing. Conclusions These data provide us with a platform with which to potentially enhance embryo selection for transfer.

2014-01-01

30

Endometrial thickness, Caucasian ethnicity, and age predict clinical pregnancy following fresh blastocyst embryo transfer: a retrospective cohort  

PubMed Central

Background In-vitro fertilization (IVF) with blastocyst as opposed to cleavage stage embryos has been advocated to improve success rates. Limited information exists on which to predict which patients undergoing blastocyst embryo transfer (BET) will achieve pregnancy. This study's objective was to evaluate the predictive value of patient and cycle characteristics for clinical pregnancy following fresh BET. Methods This was a retrospective cohort study from 2003–2007 at an academic assisted reproductive program. 114 women with infertility underwent fresh IVF with embryo transfer. We studied patients undergoing transfer of embryos at the blastocyst stage of development. Our main outcome of interest was clinical pregnancy. Clinical pregnancy and its associations with patient characteristics (age, body mass index, FSH, ethnicity) and cycle parameters (thickness of endometrial stripe, number eggs, available cleaving embryos, number blastocysts available, transferred, and cryopreserved, and embryo quality) were examined using Student's T test and Mann-Whitney-U tests as appropriate. Multivariable logistic regression models were created to determine independent predictors of CP following BET. Receiver Operating Characteristic analyses were used to determine the optimal thickness of endometrial stripe for predicting clinical pregnancy. Results Patients achieving clinical pregnancy demonstrated a thicker endometrial stripe and were younger preceding embryo transfer. On multivariable logistic regression analyses, Caucasian ethnicity (OR 2.641, 95% CI 1.054–6.617), thickness of endometrial stripe, (OR 1.185, 95% CI 1.006–1.396) and age (OR 0.879, 95% CI 0.789–0.980) predicted clinical pregnancy. By receiver operating characteristic analysis, endometrial stripe ? 9.4 mm demonstrated a sensitivity of 83% for predicting clinical pregnancy following BET. Conclusion In a cohort of patients undergoing fresh BET, thicker endometrial stripe, Caucasian ethnicity, and younger age are positive predictors of clinical pregnancy after fresh BET. These findings may be useful in clinical management of infertile patients undergoing fresh BET cycles.

Traub, Michael L; Van Arsdale, Anne; Pal, Lubna; Jindal, Sangita; Santoro, Nanette

2009-01-01

31

Factors affecting the outcome of human blastocyst vitrification  

PubMed Central

With single blastocyst transfer practice becoming more common in ART, there is a greater demand for a convenient and reliable cryostorage of surplus blastocysts. Vitrification has emerged in the last decade as an alternative promising substitute for slow freezing. Blastocysts represent a unique challenge in cryostorage due to their size, multicellular structure and presence of blastocoele. The continuous acquisition of experience and introduction of many different technological developments has led to the improvement of vitrification as a technology and improved the results of its application in blastocyst cryostorage. The current information concerning safety and efficacy of the vitrification of blastocysts will be reviewed along with the variables that can impact the outcome of the procedure.

Kader, Amr A; Choi, Audrey; Orief, Yasser; Agarwal, Ashok

2009-01-01

32

Blastocyst Transfer Ameliorates Live Birth Rate Compared with Cleavage-Stage Embryos Transfer in Fresh In Vitro Fertilization or Intracytoplasmic Sperm Injection Cycles: Reviews and Meta-Analysis  

PubMed Central

Purpose Blastocyst transfer has been recommended to raise the implantation rate without affecting the pregnancy rate. The objective of this meta-analysis is to systematically evaluate whether the live birth rate and other pregnancy outcomes can be improved by blastocyst transfer compared with cleavage-stage embryos transfer. Materials and Methods EMBASE and MEDLINE databases were searched for papers published between March 2004 and March 2013. An extensive range of the electronic databases yielded initially 317 studies from which seven trials met the inclusion criteria for further analysis. Our outcome measures were the live birth rate, clinical pregnancy rate, implantation rate, ongoing pregnancy rate, multiple pregnancy rate, first trimester miscarriage rate and ectopic pregnancy rate. Fixed effects models were chosen to calculate the odds ratio (OR). Results Seven trials (n=1446 cases) were finally analyzed. Compared with cleavage-stage embryos transfer, the blastocyst transfer was statistically significantly associated with an increase in clinical pregnancy rate [OR 1.43; 95% confidence interval (CI), 1.15-1.78], implantation rate (OR 1.38; 95% CI, 1.09-1.74) and ongoing pregnancy rate (OR 2.15; 95% CI, 1.57-2.94), and also a reduction in the probability of first trimester miscarriage rate (OR 0.51; 95% CI, 0.30-0.87). The improvement in the live birth rate was also observed (OR 1.77; 95% CI, 1.32-2.37). Moreover, there was no evidence of difference in multiple pregnancy and ectopic pregnancy rates. Conclusion The available evidences suggest that live birth and other pregnancy outcomes after fresh in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) are significantly improved following blastocyst transfer as compared to cleavage-stage embryo transfer.

Wang, Shan-Shan

2014-01-01

33

Forced collapse of the blastocoel enhances survival of cryotop vitrified bovine hatching/hatched blastocysts derived from in vitro fertilization and somatic cell nuclear transfer.  

PubMed

Freezing of bovine blastocysts has been widely used to improve the feasibility of cattle production by the embryo transfer technique. However, the low survival of vitrified-warmed embryos and their further development are crucial problems. Particularly, the production of offspring in vitrified-warmed bovine hatching/hatched blastocysts derived from in vitro fertilization (IVF) and somatic cell nuclear transfer (SCNT) is very low. Thus, we examined the effects of forced blastocoel collapse (FBC) before vitrification of bovine IVF- and SCNT-derived hatching/hatched embryos on the survival rate and apoptosis index after warming. Under optimal conditions, the overall survival rates in vitrified-warmed bovine IVF- and SCNT-derived hatching/hatched blastocysts were higher in FBC groups than in non-FBC groups (p<0.05). The total cell numbers of vitrified-warmed hatching/hatched blastocysts were higher in FBC groups than in non-FBC groups (p<0.05). Otherwise, the number of apoptotic positive cells of vitrified-warmed hatching/hatched blastocysts was lower in FBC groups than in non-FBC groups (p<0.05). Taken together, these findings suggest that forced collapse of the blastocoel using a pulled Pasteur pipette is an effective pretreatment technique for vitrification of bovine IVF- and SCNT-derived hatching/hatched blastocysts. PMID:23376491

Min, Sung-Hun; Lee, Enok; Son, Hyeong-Hoon; Yeon, Ji-Yeong; Koo, Deog-Bon

2013-04-01

34

A single blastocyst assay optimized for detecting CRISPR/Cas9 system-induced indel mutations in mice  

PubMed Central

Background Microinjection of clustered regulatory interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9)-related RNA and DNA into fertilized eggs is a novel approach for creating gene-modified mice. Blastocysts obtained just before implantation may be appropriate for testing the fidelity of CRIPSR/Cas9-mediated genome editing because they can be individually handled in vitro and obtained 3 days after microinjection, thus allowing researchers to check mutations rapidly. However, it is not known whether indel mutations caused by the CRISPR/Cas9 system can be reproducibly detected in embryos. In this study, we assessed the detection of CRISPR/Cas9-induced mutations in embryos. Results T7 endonuclease I was more effective than Surveyor nuclease for detecting mutations in annealed fragments derived from 2 plasmids, which contained nearly identical sequences. Mouse fertilized eggs were microinjected with CRISPR/Cas9-related RNA/DNA to examine whether non-homologous end joining-mediated knockout and homologous recombination-mediated knockin occurred in the endogenous receptor (G protein-coupled) activity modifying protein 2 (Ramp2) gene. Individual blastocysts were lysed to obtain crude DNA solutions, which were used for polymerase chain reaction (PCR) assays. T7 endonuclease I-based PCR and sequencing analysis demonstrated that 25–100% of the embryos were knockout embryos and 7–57% of the embryos were knockin embryos. Our results also established that crude DNA from a single blastocyst was an appropriate template for Whole genome amplification and subsequent assessment by PCR and the T7 endonuclease I-based assay. Conclusions The single blastocyst-based assay was useful for determining whether CRISPR/Cas9-mediated genome editing worked in murine embryos.

2014-01-01

35

Improved blastocyst development of single cow OPU-derived presumptive zygotes by group culture with agarose-embedded helper embryos  

PubMed Central

Background The in vitro culture of presumed zygotes derived from single cow ovum pick-up (OPU) is important for the production of quality blastocysts maintaining pedigree. The aim of the present study was to evaluate the agar chip-embedded helper embryo coculture system for single cow OPU-derived zygotes by assessing embryo quality. Methods Cumulus oocyte complexes (COCs) were collected from Hanwoo cows with high genetic merit twice a week using the ultra-sound guided OPU technique and from slaughterhouse ovaries. The Hanwoo cow COCs and slaughterhouse ovaries were matured in vitro, fertilized in vitro with thawed Hanwoo sperm and cultured for 24 h. The presumed zygotes were subsequently placed in three different culture systems: (1) control OPU (controlOPU) with single cow OPU-derived presumed zygotes (2~8); (2) agar chip-embedded slaughterhouse helper embryo coculture (agarOPU) with ten presumed zygotes including all presumed zygotes from a cow (2~8) and the rest from agar chip-embedded slaughterhouse presumed zygotes (8~2); and (3) slaughterhouse in vitro embryo production (sIVP) with ten slaughterhouse ovary-derived presumed zygotes, each in 50 ?L droplets. Day 8 blastocysts were assayed for apoptosis and gene expression using real time PCR. Results The coculture system promoted higher blastocyst development in OPU zygotes compared to control OPU zygotes cultured alone (35.2 vs. 13.9%; P < 0.01). Genes predicted to be involved in implantation failure and/or embryo resorption were down-regulated (P < 0.05) in control OPU zygotes (CD9, 0.4-fold; AKRAB1, 0.3-fold) and in cocultured zygotes (CD9, 0.3-fold; AKRAB1, 0.3-fold) compared to sIVP blastocysts (1.0-fold). Moreover, genes involved in implantation and/or normal calf delivery were up-regulated (P < 0.05 to P < 0.01) in control OPU zygotes (PGSH2, 5.0-fold; TXN, 4.3-fold; PLAU, 1.7-fold) and cocultured zygotes (PGSH2, 14.5-fold; TXN, 3.2-fold; PLAU, 6.8-fold) compared to sIVP (1.0-fold) blastocysts. However, the expression of PLAC8, TGF-?1, ODC1, ATP5A1 and CASP3 did not differ between the three culture groups. Conclusions Results show that the agar chip-embedded helper embryo coculture system enhances developmental competence and embryo quality in cultures of limited numbers of high pedigree single cow OPU presumed zygotes.

2011-01-01

36

Effect of Sperm DNA Fragmentation on Clinical Outcome of Frozen-Thawed Embryo Transfer and on Blastocyst Formation  

PubMed Central

During the last decades, many studies have shown the possible influence of sperm DNA fragmentation on assisted reproductive technique outcomes. However, little is known about the impact of sperm DNA fragmentation on the clinical outcome of frozen-thawed embryo transfer (FET) from cycles of conventional in vitro fertilization (IVF) and intra-cytoplasmic sperm injection (ICSI). In the present study, the relationship between sperm DNA fragmentation (SDF) and FET clinical outcomes in IVF and ICSI cycles was analyzed. A total of 1082 FET cycles with cleavage stage embryos (C-FET) (855 from IVF and 227 from ICSI) and 653 frozen-thawed blastocyst transfer cycles (B-FET) (525 from IVF and 128 from ICSI) were included. There was no significant change in clinical pregnancy, biochemical pregnancy and miscarriage rates in the group with a SDF >30% compared with the group with a SDF ?30% in IVF and ICSI cycles with C-FET or B-FET. Also, there was no significant impact on the FET clinic outcome in IVF and ICSI when different values of SDF (such as 10%, 20%, 25%, 35%, and 40%) were taken as proposed threshold levels. However, the blastulation rates were significantly higher in the SDF ?30% group in ICSI cycle. Taken together, our data show that sperm DNA fragmentation measured by Sperm Chromatin Dispersion (SCD) test is not associated with clinical outcome of FET in IVF and ICSI. Nonetheless, SDF is related to the blastocyst formation in ICSI cycles.

Ni, Wuhua; Xiao, Shiquan; Qiu, Xiufang; Jin, Jianyuan; Pan, Chengshuang; Li, Yan; Fei, Qianjin; Yang, Xu; Zhang, Liya; Huang, Xuefeng

2014-01-01

37

Different perspectives of patients and health care professionals on the potential benefits and risks of blastocyst culture and multiple embryo transfer  

Microsoft Academic Search

BACKGROUND: A trade-off exists between the risk of multiple pregnancy and prospects of pregnancy itself in assisted reproduction. Blastocyst culture and embryo transfer after ~5 days may be one method of reconciling this dilemma, although a controversial one. METHODS AND RESULTS: We presented a questionnaire to groups of patients, embryologists and clinicians to solicit views on the potential benefits and

G. M. Hartshorne; R. J. Lilford

2002-01-01

38

Increasing glucose in KSOMaa basal medium on culture Day 2 improves in vitro development of cloned caprine blastocysts produced via intraspecies and interspecies somatic cell nuclear transfer.  

PubMed

This study was conducted to evaluate the efficiency of potassium simplex optimization medium with amino acids (KSOMaa) as a basal culture medium for caprine intraspecies somatic cell nuclear transfer (SCNT) and caprine-bovine interspecies somatic cell nuclear transfer (iSCNT) embryos. The effect of increased glucose as an energy substrate for late stage development of cloned caprine embryos in vitro was also evaluated. Enucleated caprine and bovine in vitro matured oocytes at metaphase II were reconstructed with caprine ear skin fibroblast cells for the SCNT and iSCNT studies. The cloned caprine and parthenogenetic embryos were cultured in either KSOMaa with 0.2 mM glucose for 8 days (Treatment 1) or KSOMaa for 2 days followed by KSOMaa with additional glucose at a final concentration of 2.78 mM for the last 6 days (Treatment 2). There were no significant differences in the cleavage rates of SCNT (80.7%) and iSCNT (78.0%) embryos cultured in KSOMaa medium. Both Treatment 1 and Treatment 2 could support in vitro development of SCNT and iSCNT embryos to the blastocyst stage. However, the blastocyst development rate of SCNT embryos was significantly higher (P < 0.05) in Treatment 2 compared to Treatment 1. Increasing glucose for later stage embryo development (8-cell stage onwards) during in vitro culture (IVC) in Treatment 2 also improved both caprine SCNT and iSCNT embryo development to the hatched blastocyst stage. In conclusion, this study shows that cloned caprine embryos derived from SCNT and iSCNT could develop to the blastocyst stage in KSOMaa medium supplemented with additional glucose (2.78 mM, final concentration) and this medium also supported hatching of caprine cloned blastocysts. PMID:22704387

Kwong, P J; Abdullah, R B; Wan Khadijah, W E

2012-09-01

39

Successful vitrification of bovine blastocysts on paper container.  

PubMed

Cryopreservation of bovine embryos can be performed by a variety of methods with variable degree of success. Here, we report a new, easy to perform, simple, inexpensive, and successful method for vitrification of bovine blastocysts. In vitro produced bovine blastocysts were exposed to vitrification solution (5.5 m ethylene glycol, 10% serum and 1% sucrose) in one single step for 20 s, loaded on a paper container prepared from commonly available non-slippery, absorbent writing paper, and then were directly plunged into liquid nitrogen for storage. Vitrified blastocysts were warmed by serial rinsing in 0.5, 0.25 and 0.125 m sucrose solution for 1 min each. Results showed that one step exposure of bovine blastocysts to cryoprotective agents was sufficient to achieve successful cryopreservation. Under these conditions, more than 95% of blastocysts survived the vitrification-warming on paper containers which was significantly higher than those obtained from other containers, such as electron microscope (EM) grid (78.1%), open pulled straw (OPS; 80.2%), cryoloop (76.2%) or plastic straw (73.9%). Embryo transfer of blastocysts vitrified-warmed on paper container resulted in successful conception (19.3%) and full-term live birth of offspring (12.3%) which were lower (P < 0.05) than those obtained from non-vitrified blastocysts (38.0 and 32.7%) but were comparable (P > 0.05) to those obtained from blastocysts vitrified-warmed on EM grid (23.3 and 14.2%). Our results, therefore, suggest that paper may be an inexpensive and useful container for the cryopreservation of animal embryos. PMID:22763071

Kim, Y M; Uhm, S J; Gupta, M K; Yang, J S; Lim, J-G; Das, Z C; Heo, Y T; Chung, H-J; Kong, I-K; Kim, N-H; Lee, H T; Ko, D H

2012-09-15

40

Passage number of porcine embryonic germ cells affects epigenetic status and blastocyst rate following somatic cell nuclear transfer.  

PubMed

Epigenetic instability of donor cells due to long-term in vitro culture may influence the success rate of subsequent somatic cell nuclear transfer (SCNT). Therefore, the present study was designed (1) to investigate the epigenetic changes after prolonged culture in vitro of porcine embryonic germ (EG) cells, including differences in expression levels of both DNA methylation and demethylation-related genes and catalyses of histone modifications, and (2) to assess the efficiency of SCNT using EG cells from different passages. Results showed that genes either associated with DNA demethylation including DNMTs and TET1 or genes related to histone acetylation including HDACs were highly expressed in EG cells at higher passages when compared to EG cells at lower passages. In addition, the expression level of H3K27me3 functional methylase EZH2 increased while no changes were observed on H3K27me3 demethylase JMJD3 in relation to passage number. Moreover, the expression levels of both the H3K4me3 methylase MLL1 and the H3K4me3 demethylase RBP2 were increased at high passages. By using lower passage (numbers 3-5) EG cells as donor cells, the SCNT efficiency was significantly lower compared with use of fetal fibroblast donor cells. However, similar blastocyst rates were achieved when using higher passage (numbers 9-12) EG cells as donor cells. In conclusion, the present study suggests that the epigenetic status of EG cells change with increasing passage numbers, and that higher passage number EG cells are better primed for SCNT. PMID:24726409

Li, Juan; Gao, Yu; Petkov, Stoyan; Purup, Stig; Hyttel, Poul; Callesen, Henrik

2014-06-10

41

Embryo selection strategy in sibling oocytes: a novel approach to measuring the likelihood of single?embryo transfer using a mouse embryo transfer model.  

PubMed

The present study investigated the effect of embryo transfer on post-implantation development using different fertilization approaches in sibling oocyte procedures. C57BL/6, DBA/2, C3H/HeJ and ICR mice were used at 8-10 weeks of age. Mature oocytes were collected, divided into two groups and fertilized using in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Different numbers of the resulting blastocysts were then transferred into recipients and designated as either: The single embryo transfer (SET) I model (one transferred embryo), the SET II model (six transferred embryos) or the multiple embryo transfer (MET) model (24 transferred embryos). The development efficiency, cell number, number of apoptotic cells in blastocysts, pregnancy efficiency, delivery rate and cumulative pregnancy efficiency were analyzed. IVF-fertilized embryos exhibited higher blastocyst development competence and embryo quality compared with ICSI embryos. The pregnancy and delivery efficiency was not identified to be significantly different between the two SET models, but it was lower in these two models than in the MET model. The cumulative pregnancy efficiency in SET models, calculated using a mathematical equation, was not decreased. In conclusion, embryo quality was shown to be the primary factor in selecting embryos prior to embryo transfer using sibling oocytes. In addition, single blastocyst transfer can be performed in sibling oocytes without compromising cumulative pregnancy rates, independent of the fertilization approach. PMID:24584547

Xu, Feng-Qin; Liu, Rong; Ma, Ying; Liu, Li; Liang, Ju-Yan; Ma, Yan

2014-05-01

42

Factors affecting the success of human blastocyst development and pregnancy following in vitro fertilization and embryo transfer 1 1 Portions of these data were previously published in Jones et al. (7)  

Microsoft Academic Search

Objective: To determine the factors affecting blastocyst development and pregnancy after IVF and ET.Design: Retrospective analysis of data arising from a clinical trial.Setting: Private in vitro fertilization clinic.Patient(s): Fifty-six patients aged ?40 years, undergoing IVF procedures for infertility, recruited specifically for blastocyst transfer.Intervention(s): All zygotes were cultured to days 5 or 6 after insemination, and one to four of the

Gayle M Jones; Alan O Trounson; Nick Lolatgis; Carl Wood

1998-01-01

43

Selection of competent blastocysts for transfer by combining time-lapse monitoring and array CGH testing for patients undergoing preimplantation genetic screening: a prospective study with sibling oocytes  

PubMed Central

Background Recent advances in time-lapse monitoring in IVF treatment have provided new morphokinetic markers for embryonic competence. However, there is still very limited information about the relationship between morphokinetic parameters, chromosomal compositions and implantation potential. Accordingly, this study aimed at investigating the effects of selecting competent blastocysts for transfer by combining time-lapse monitoring and array CGH testing on pregnancy and implantation outcomes for patients undergoing preimplantation genetic screening (PGS). Methods A total of 1163 metaphase II (MII) oocytes were retrieved from 138 PGS patients at a mean age of 36.6 ± 2.4 years. These sibling MII oocytes were then randomized into two groups after ICSI: 1) Group A, oocytes (n = 582) were cultured in the time-lapse system and 2) Group B, oocytes (n = 581) were cultured in the conventional incubator. For both groups, whole genomic amplification and array CGH testing were performed after trophectoderm biopsy on day 5. One to two euploid blastocysts within the most predictive morphokinetic parameters (Group A) or with the best morphological grade available (Group B) were selected for transfer to individual patients on day 6. Ongoing pregnancy and implantation rates were compared between the two groups. Results There were significant differences in clinical pregnancy rates between Group A and Group B (71.1% vs. 45.9%, respectively, p = 0.037). The observed implantation rate per embryo transfer significantly increased in Group A compared to Group B (66.2% vs. 42.4%, respectively, p = 0.011). Moreover, a significant increase in ongoing pregnancy rates was also observed in Group A compared to Group B (68.9% vs. 40.5%. respectively, p = 0.019). However, there was no significant difference in miscarriage rate between the time-lapse system and the conventional incubator (3.1% vs. 11.8%, respectively, p = 0.273). Conclusions This is the first prospective investigation using sibling oocytes to evaluate the efficiency of selecting competent blastocysts for transfer by combining time-lapse monitoring and array CGH testing for PGS patients. Our data clearly demonstrate that the combination of these two advanced technologies to select competent blastocysts for transfer results in improved implantation and ongoing pregnancy rates for PGS patients.

2014-01-01

44

Vitrification demonstrates significant improvement versus slow freezing of human blastocysts  

Microsoft Academic Search

Blastocyst culture has reduced the number of embryos transferred per cycle, whilst simultaneously creating new quandaries regarding supernumerary blastocyst cryopreservation. This retrospective study was undertaken to compare a slow freezing protocol to a vitrification protocol for cryopreservation of day 5 and day 6 human blastocysts. To demonstrate this, the survival, implantation rate and pregnancy rates were compared after thawing, assessment

Ed Stehlik; Joni Stehlik; K Paul Katayama; Masashige Kuwayama; Varya Jambor; Rebecca Brohammer; Osama Kato

2005-01-01

45

Birth of a healthy baby following vitrification of human blastocysts  

Microsoft Academic Search

Objective: To assess vitrification of human blastocysts.Design: Retrospective study of blastocyst vitrification.Setting: A private clinic.Patient(s): Twenty couples with different types of infertility.Intervention(s): Blastocysts were frozen with rapid vitrification and then transferred after thawing. We vitrified blastocysts using a modification of Ishimori’s vitrification solution of ethylene glycol and dimethyl sulfoxide (VSED).Main Outcome Measure(s): After thawing, survival was defined by the embryo’s

Yoshimasa Yokota; Setsuko Sato; Mikako Yokota; Hidemi Yokota; Yasuhisa Araki

2001-01-01

46

Comparative Genomic Hybridization Selection of Blastocysts for Repeated Implantation Failure Treatment: A Pilot Study  

PubMed Central

The aim of this study is to determine if the use of preimplantation genetic screening (PGS) by array comparative genomic hybridization (array CGH) and transfer of a single euploid blastocyst in patients with repeated implantation failure (RIF) can improve clinical results. Three patient groups are compared: 43 couples with RIF for whom embryos were selected by array CGH (group RIF-PGS), 33 couples with the same history for whom array CGH was not performed (group RIF NO PGS), and 45 good prognosis infertile couples with array CGH selected embryos (group NO RIF PGS). A single euploid blastocyst was transferred in groups RIF-PGS and NO RIF PGS. Array CGH was not performed in group RIF NO PGS in which 1-2 blastocysts were transferred. One monoembryonic sac with heartbeat was found in 28 patients of group RIF PGS and 31 patients of group NO RIF PGS showing similar clinical pregnancy and implantation rates (68.3% and 70.5%, resp.). In contrast, an embryonic sac with heartbeat was only detected in 7 (21.2%) patients of group RIF NO PGS. In conclusion, PGS by array CGH with single euploid blastocyst transfer appears to be a successful strategy for patients with multiple failed IVF attempts.

Greco, Ermanno; Bono, Sara; Ruberti, Alessandra; Lobascio, Anna Maria; Greco, Pierfrancesco; Biricik, Anil; Spizzichino, Letizia; Greco, Alessia; Tesarik, Jan; Minasi, Maria Giulia; Fiorentino, Francesco

2014-01-01

47

Minimal ovarian stimulation combined with elective single embryo transfer policy: age-specific results of a large, single-centre, Japanese cohort  

PubMed Central

Background The two main complications associated with the use of assisted reproduction techniques, ovarian hyperstimulation syndrome and multiple pregnancies, could be eliminated by milder ovarian stimulation protocols and the increased use of a single embryo transfer (SET) policy. A retrospective, cohort study was performed in private infertility centre to evaluate the embryological and clinical results of a large exclusively SET program according to patient age (lower or equal 29, 30–34, 35–39, 40–44 and equal or higher 45?years). Materials A total of 7,244 infertile patients have undergone 20,244 cycles with a clomiphene-based minimal stimulation or natural cycle IVF protocol during 2008. Following oocyte retrieval, fertilization and embryo culture a total of 10,401 fresh or frozen single embryo transfer procedures were performed involving cleavage-stage embryos or blastocysts. Results Successful oocyte retrieval rate (78.0?%) showed no age-dependent decrease until 45?years. Fertilization (80.3?%) and cleavage (91.1?%) rates were not significantly different between age groups. Blastocyst formation (70.1?% to 22.8?%) and overall live birth rates (35.9?% to 2?%) showed an age-dependent decrease. Frozen-thawed blastocyst transfer cycles gave the highest chance of live birth per embryo transfer (41.3?% to 6.1?%). Conclusions High fertilization and cleavage rates were obtained regardless of age whereas blastocyst formation and live birth rates showed an age-dependent decrease. An elective single embryo transfer program based on a minimal ovarian stimulation protocol yields acceptable live birth rates per embryo transfer in infertile patients up until their mid-forties. However in very advanced age patients (equal or higher 45?years old) success rates fall below 1?%.

2012-01-01

48

Successful Same-Cycle Blastocyst Transfer following Laparoscopic Ovarian Detorsion: A Report of Two Cases and Literature Review  

PubMed Central

Ovarian stimulation increases the risk of ovarian torsion. During an in vitro fertilization (IVF) cycle, the effects of ovarian torsion on retrieved oocytes and subsequent pregnancy chances are not clear. Moreover, no cases of ovarian torsion occurring following oocyte retrieval but prior to same-cycle embryo transfer have been reported. Such cases present a clinical dilemma with respect to optimal timing of embryo transfer. We report two cases of a 41-year-old and a 32-year-old infertility patients undergoing IVF who were diagnosed with ovarian torsion within several days following oocyte retrieval. Both patients were treated by early laparoscopic evaluation and detorsion followed by day five embryo transfer, resulting in successful pregnancies. Therefore, after prompt laparoscopic ovarian untwisting of a torsed ovary following egg retrieval, embryo transfer may be performed as originally scheduled during the concurrent cycle leading to favorable pregnancy outcomes.

Seifer, David B.; Grazi, Richard V.

2014-01-01

49

Cryopreservation of rat blastocysts by vitrification.  

PubMed

Rat blastocysts equilibrated with vitrification solution (VS1), consisting of dimethyl sulfoxide, acetamide, propylene glycol, and polyethylene glycol were plunged directly into liquid nitrogen. The embryo suspension are solidified by an extreme elevation in viscosity of solution. The embryos are cryopreserved by vitrification without intra- and extracellular ice formation. The proportion of morphologically normal embryos after cooling and warming was 79% (117/149) and all (48/48) of the embryos cultured were developed to expanded or hatched blastocysts. Normal live young were obtained 41% of the time (28/69) after transfer of the cooled and warmed embryos to pseudopregnant recipients. PMID:3371062

Kono, T; Suzuki, O; Tsunoda, Y

1988-04-01

50

Successful application of the strategy of blastocyst biopsy, vitrification, whole genome amplification, and thawed embryo transfer for preimplantation genetic diagnosis of neurofibromatosis type 1  

Microsoft Academic Search

ObjectivePreimplantation genetic diagnosis (PGD) offers an alternative for women to carry an unaffected fetus risk of hereditary diseases. Trophectoderm biopsy may provide more cells for accurate diagnosis. However, the time allowed for transportation of the specimens to the laboratory and performance of molecular diagnosis is limited. We designed a PGD program of trophectoderm biopsy, vitrification of blastocysts, whole genome amplification

Yi-Lin Chen; Chia-Cheng Hung; Shin-Yu Lin; Mei-Ya Fang; Yi-Yi Tsai; Li-Jung Chang; Chien-Nan Lee; Yi-Ning Su; Shee-Uan Chen; Yu-Shih Yang

2011-01-01

51

Effect of the size of zona pellucida opening by laser assisted hatching on clinical outcome of frozen cleaved embryos that were cultured to blastocyst after thawing in women with multiple implantation failures of embryo transfer: a retrospective study  

Microsoft Academic Search

Purpose  To evaluate the effect of the size of zona pellucida opening by laser assisted hatching for frozen cleaved embryo that were\\u000a thawed after both fresh and frozen cleaved embryo transfer cycles failed and were cultured to blastocyst after thawing in\\u000a patients with multiple implantation failures.\\u000a \\u000a \\u000a \\u000a Materials and methods  Of 101 consecutive procedures (October 2003 to June 2006), 30 patients declined to

Kenichiro Hiraoka; Megumi Fuchiwaki; Kaori Hiraoka; Toshitaka Horiuchi; Tomoyo Murakami; Masayuki Kinutani; Kazuo Kinutani

2008-01-01

52

The Effects of 5-Aza-2?- Deoxycytidine and Trichostatin A on Gene Expression and DNA Methylation Status in Cloned Bovine Blastocysts  

PubMed Central

Abstract We previously found that treatment of both donor cells and early cloned embryos with combination of 5-aza-2?-deoxycytidine (5-aza-dC) and trichostatin A (TSA) significantly improve the in vitro and full-term development of nuclear transfer (NT) bovine embryos. To investigate how this treatment improved the epigenetic reprogramming of somatic cell nuclei, we compared the expression levels of DNA methylation-, chromatin structure-, and development-related genes in in vitro fertilized (IVF group), NT (C-NT group), and 5-aza-dC and TSA-treated NT (T-NT group) single blastocyst using quantitative real-time PCR. We also compared the DNA methylation status of satellite I among three groups using bisulfite sequencing analysis and combined bisulfite restriction analysis (COBRA). There were significantly lower levels of DNMT1, DNMT3b, HDAC2, and IGF2 transcripts in T-NT blastocysts than in C-NT blastocysts, whereas the relative abundance of OCT4 and SOX2 mRNA was significantly increased in T-NT blastocysts compared to C-NT blastocysts. In addition, the treatment also reduced the DNA methylation levels of NT blastocysts on satellite I sequence. It is likely that TSA may act synergistically with 5-aza-dC to exert such modifications in gene expression and DNA methylation, subsequently enhancing developmental potential (in vitro and full-term) of treated cloned embryos.

Wang, Yongsheng; Su, Jianmin; Wang, Lijun; Xu, Wenbing; Quan, Fusheng; Liu, Jun

2011-01-01

53

Degradation of estrogen receptor ? in activated blastocysts is associated with implantation in the delayed implantation mouse model.  

PubMed

Implantation of a blastocyst into a receptive uterus involves a series of highly coordinated cellular and molecular events directed by ovarian estrogen and progesterone. In particular, estrogen is essential for on-time uterine receptivity and blastocyst activation in mice. Although estrogen receptor ? (ER?) is expressed in blastocysts, its targeted disruption leaves embryonic development and implantation unaffected. Therefore, the role of ER? in implanting blastocysts remains unclear. Using a delayed implantation model in mice, we showed increased expression of ER? in implantation-induced (activated) blastocysts; however, this ER? expression in activated blastocysts decreased within 6-h culture. In contrast, breast cancer 1 (Brca1) was maintained in the blastocysts during the culture. The treatment of activated blastocysts with the proteasome inhibitor MG132 demonstrated that proteolysis is associated with down-regulation of ER? expression in activated blastocysts. Embryo transfer of MG132-treated activated blastocysts into recipient mice on the morning of Day 4 of pseudopregnancy (Day 1 = vaginal plug) showed a decreased implantation rate, whereas combined treatment with MG132 and the ER antagonist, ICI 182,780, resulted in recovery of the rate of implantation. This study has revealed that down-regulation of ER? in activated blastocyst is associated with completion of blastocyst implantation after embryo transfer on the morning of Day 4 of pseudopregnancy. Our results also suggest that selective protein turnover, such as that of ER?, occurs in activated blastocysts, while expression of other proteins, including Brca1, is maintained at the same stage. PMID:24442344

Saito, Kyosuke; Furukawa, Etsuko; Kobayashi, Mitsuru; Fukui, Emiko; Yoshizawa, Midori; Matsumoto, Hiromichi

2014-05-01

54

[Morphological identification of blastocysts].  

PubMed

The authors have attempted to systematize the currently known specific morphological features of the composition of Blastocystis spp. existing in different forms and to present this material as a reference table, by understanding the need for further data clarification. In addition, the paper describes observations of variations in the forms of human blastocysts. In particular, it depicts the species of multinucleated cysts, the identification of which may cause difficulties in diagnosing and differentiating these forms with some representative species of the genus Entamoeba. PMID:24738219

2014-01-01

55

Single embryo transfer is an option in frozen embryo transfer  

Microsoft Academic Search

BACKGROUND: A good strategy to decrease multiple pregnancy rate in assisted reproduction technology (ART) is the use of single embryo transfer (SET). METHODS: This retrospective study analysed 1647 frozen embryo transfers carried out during 1998-2003 in Helsinki University Central Hospital; of these, 872 were double embryo transfers (DETs) and 775 SETs. The SET group included 140 (18.1%) elective SETs (eSETs).

C. Hydén-Granskog; L. Unkila-Kallio; M. Halttunen; A. Tiitinen

56

Single embryo transfer with comprehensive chromosome screening results in improved ongoing pregnancy rates and decreased miscarriage rates  

PubMed Central

BACKGROUND Single embryo transfer (SET) provides the most certain means to reduce the risk of multiple gestation. Regrettably, prospective trials of SET have demonstrated reductions in per-cycle delivery rates. A validated method of comprehensive chromosome screening (CCS) has the potential to optimize SET by transferring only euploid embryos. This retrospective study evaluates the efficacy of SET with CCS in an infertile population. METHODS Overall and age-controlled ongoing pregnancy rates (OPR) were compared between women undergoing SET following CCS (CCS-SET, n= 140) and those undergoing SET without aneuploidy screening (control SET, n= 182). All transfers were at the blastocyst stage, with CCS performed after trophectoderm biopsy of expanded blastocysts and analysis with rapid PCR allowing for fresh transfer. RESULTS In the CCS-SET and control SET groups, an OPR of 55.0 and 41.8%, respectively, was obtained. The OPR was lower for the control group (P< 0.01) despite a younger age than the CCS group (37.3 ± 3.4 versus 34.2 ± 3.9 years; P< 0.001). Birthweight and gestational age at delivery were equivalent. The proportion of clinical pregnancies resulting in miscarriage was higher in the control group (24.8 versus 10.5%, P< 0.01), with more patients requiring surgical interventions for aneuploid pregnancies. There was one monozygotic twin delivery in the CCS group and none in the control group. CONCLUSIONS Compared with traditional blastocyst SET, SET after trophectoderm biopsy and rapid PCR-based CCS increases OPR and reduces the miscarriage rate. The enhanced selection empowered by CCS with SET may provide a practical way to eliminate multi-zygotic multiple gestation without compromising clinical outcomes per cycle.

Forman, E.J.; Tao, X.; Ferry, K.M.; Taylor, D.; Treff, N.R.; Scott, R.T.

2012-01-01

57

Blastocyst formation--good indicator of clinical results after ICSI with testicular spermatozoa  

Microsoft Academic Search

BACKGROUND: The aim of this study was to evaluate the role of blastocyst culture in patients with azoospermia. METHODS: In 98 cycles embryos were cultured for 2 days and in 128 cycles for 5 days to reach the blastocyst stage; a maximum of two of the most developed embryos were transferred in each group. RESULTS: There was a negative correlation

I. Virant-Klun; T. Tomazevic; B. Zorn; L. Bacer-Kermavner; J. Mivsek; H. Meden-Vrtovec

2003-01-01

58

Preferable correlation to blastocyst development and pregnancy rates with a new embryo grading system specific for day 3 embryos  

Microsoft Academic Search

Purpose: To investigate the cleavage stage embryo quality by the correlation between the morphological features and blastocyst development\\u000a rate to develop a new embryo grading system.\\u000a \\u000a \\u000a Methods: A retrospective analysis, including 216 cycles of cleavage stage embryo transfer and 251 cycles of blastocyst transfer.\\u000a The correlation with blastocyst development of the embryo cleavage stage, fragmentation and uniformity of blastomeres was

Masao Nomura; Akira Iwase; Kenji Furui; Takeshi Kitagawa; Yuka Matsui; Manami Yoshikawa; Fumitaka Kikkawa

2007-01-01

59

The culture of human cleavage stage embryos alone or in groups: effect upon blastocyst utilization rates and implantation.  

PubMed

The effect of cleavage-stage group culture (CGC; embryos cultured in groups of three or more for the first 3 days and then individually to blastocyst) was compared to extended single embryo culture (ESC; embryos cultured individually to the blastocyst stage). While implantation and ongoing pregnancy rates were similar between groups, the blastocyst utilization rate (number of blastocysts suitable for freezing and thawing/total number of embryos cultured to Day 5 and 6) was significantly higher when embryos were cultured in CGC for women ?35 yrs thereby increasing the number of embryos available for clinical use for the younger women. This strategy of group culture to Day 3 would seem an ideal protocol to capitalize on an overall embryo quality in two particular settings, namely programmes wishing to (i) undertake Day 3 transfers, and (ii) keep embryos separate from Day 3 to Day5/6 for the purposes of selection. The culture system can also be applied to the embryos of older women without adverse effect, enabling the same system to be used for all embryos. PMID:21113203

Rebollar-Lazaro, Itziar; Matson, Phillip

2010-11-01

60

Utility of FT-IR imaging spectroscopy in estimating differences between the quality of bovine blastocysts  

NASA Astrophysics Data System (ADS)

This study was conducted to verify whether the FT-IR spectroscopy and Focal Plane Array (FPA) imaging can be successfully applied to estimate the quality of bovine blastocysts (on the basis of the concentration of nucleic acids and amides). The FT-IR spectra of inner cell mass from blastocysts of three different culture systems were examined. The spectral changes between blastocysts were analyzed in DNA (spectral range of 1240-950 cm-1) and protein amides (1800-1400 cm-1). Blastocyst 1 (BL1-HA) was developed from the fertilized oocyte cultured with low concentration of hialuronian (HA), Blastocyst 2 and 3 were developed from the oocytes cultured in standard conditions. Cleavage stage blastocyst 2 (BL2-SOF) has been cultured in SOF medium while blastocyst 3 (BL3-VERO) was cultured in co-culture with VERO cells. The multivariate statistical analysis (Hierarchical Cluster Analysis - HCA and Principal Component Analysis - PCA) of single cells spectra showed high similarity of cells forming the inner cell mass within single blastocyst. The main variance between the three examined blastocysts was related to amides bands. Differences in the intensities of the amides' peaks between the bovine blastocysts derived from different culture systems indicated that specific proteins reflecting the appearance of a new phenotype were produced. However, for the three blastocysts, the ?-helix typical peak was twice more intensive than the ?-sheet typical peak suggesting that the differentiation processes had been started. Taking into account the quantitative and qualitative composition of the protein into examined blastocysts, it can be assumed, that the quality of the BL1-HA turned out much more similar to BL3-VERO than to BL2-SOF. FT-IR spectroscopy can be successfully applied in reproductive biology research for quality estimation of oocytes and embryos at varied stages of their development. Moreover this technique proved to be particularly useful when the quantity of the available material for research purposes is limited.

Wieche?, A.; Opiela, J.; Lipiec, E.; Kwiatek, W. M.

2013-10-01

61

Hole transfer from single quantum dots.  

PubMed

Photoinduced hole transfer dynamics from single CdSe/CdS(3ML)/CdZnS(2ML)/ZnS(2ML) core/multishell quantum dots (QDs) to phenothiazine (PTZ) molecules were studied by single QD fluorescence spectroscopy to investigate the static and dynamic heterogeneities of the hole transfer process as well as its effect on the blinking dynamics of QDs. Ensemble-averaged transient absorption and fluorescence decay measurements show that excitons in QDs dissociate by transferring the valence band hole to PTZ with a time constant of 50 ns for the 1:1 PTZ-QD complex, and the subsequent charge recombination process (i.e., electron transfer from the conduction band of the reduced QD to oxidized PTZ to regenerate the complex in the ground state) occurs mainly on the 100 to 1000 ns time scale. Single QD-PTZ complexes show pronounced correlated fluctuations of fluorescence intensity and lifetime with time. In addition to the dynamic fluctuation, there are considerable heterogeneities of average hole transfer rate among different QD-PTZ complexes. The hole transfer process has little effect on the statistics of the off-states, which is often believed to be positively charged QDs with a valence band hole. Instead, it increases the probability of weakly emissive or "gray" states. PMID:21962001

Song, Nianhui; Zhu, Haiming; Jin, Shengye; Lian, Tianquan

2011-11-22

62

Single Molecule Spectroscopy of Electron Transfer  

SciTech Connect

The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.

Michael Holman; Ling Zang; Ruchuan Liu; David M. Adams

2009-10-20

63

One-step dilution of open-pulled-straw (OPS)-vitrified mouse blastocysts in sucrose-free medium.  

PubMed

Embryos vitrified by the open-pulled-straw (OPS) method are only briefly exposed to cryoprotectants and not fully equilibrated with the cryoprotectant. That being the case, conceivably the post-thawing de- and rehydration processes may be omitted. This would render thawing and dilution in a single step and direct transfer to recipients possible without the need for a microscope and other laboratory equipment. Morphologically intact mouse blastocysts from superovulated 5- to 8-week-old virgin female NMRI mice were vitrified according to a protocol [6] slightly modified from the classical OPS-procedure of Vajta et al. [29] consisting of exposure to 10% dimethyl-sulfoxide (Me(2)SO)+10% ethylene glycol (EG) for 1 min, followed by 20% Me(2)SO+20% EG for 20s before loading into straws that are plunged into liquid nitrogen. In Group 1, 75 blastocysts were exposed to the standard thawing and dilution regimen involving exposure to three solutions of decreasing sucrose content (Control). In Groups 2, 3 and 4, 75 blastocysts each were transferred, in a single step, to medium at 37 degrees C containing 0.66, 0.33 or 0M sucrose, respectively. After 48 h of in vitro culture the proportion of hatched blastocysts was determined. In Group 1, this proportion amounted to 82.7%, in Groups 2, 3 and 4 to 76.0%, 73.3% and 78.7%, respectively (P>0.05). To examine their potential to continue development in vivo, OPS-vitrified blastocysts thawed according to the regimens of Groups 1 and 4 were transferred to recipients (10 embryos/recipient). In Group 1, 9/10 recipients got pregnant with 4.7+/-0.6 (mean+/-SEM) fetuses, in Group 4, 8/10 recipients with 5.0+/-0.5 fetuses. The overall embryo survival rate per group was 42% for Group 1 and 40% for Group 4. All fetuses were normally developed and viable and there were no significant differences between groups (P>0.05). It may be concluded that warming and transfer of OPS-vitrified mouse embryos in a single step in medium devoid of sucrose is feasible, which is tantamount to a substantial simplification of embryo transfer operations. PMID:18761335

El-Gayar, M; Gauly, M; Holtz, W

2008-12-01

64

Embryonic factors affecting outcome from single cryopreserved embryo transfer  

Microsoft Academic Search

Multiple pregnancy minimization by single embryo transfer is becoming more prevalent, but is less common in the case of cryopreserved embryos. This study defines embryonic characteristics in single cryopreserved embryo transfers associated with success rates equivalent to those achieved when transferring two cryopreserved embryos. In a retrospective analysis of 6916 cryopreserved day-2 embryo transfer procedures, transfer of two cryopreserved embryos

David H Edgar; Janell Archer; John McBain; Harold Bourne

2007-01-01

65

In Vitro Production of Multigene Transgenic Blastocysts via Sperm-Mediated Gene Transfer Allows Rapid Screening of Constructs to Be Used in Xenotransplantation Experiments  

Microsoft Academic Search

Multigene transgenic pigs would be of benefit for large animal models and in particular for xenotransplantation, where extensive genetic manipulation of donor pigs is required to make them suitable for organ grafting to humans. We have previously produced multitransgenic pigs via sperm-mediated gene transfer (SMGT) using integrative constructs expressing 3 different reporter genes. The aim of the present work was

A. Vargiolu; S. Manzini; M. de Cecco; M. L. Bacci; M. Forni; G. Galeati; M. G. Cerrito; M. Busnelli; M. Lavitrano; R. Giovannoni

2010-01-01

66

Piglets born from centrifuged and vitrified early and peri-hatching blastocysts.  

PubMed

Cryopreservation of zona-intact porcine embryos has been relatively unsuccessful to date, although some success has been obtained with lipid reduced morulae and early blastocysts. This study adapted some vitrification protocols used successfully with late blastocysts for use with early zona-intact blastocysts, using actin depolymerization, centrifugation, and open-pulled (OPS) straws. Initially, Day 6 peri-hatching blastocysts were collected, cultured for 40 min in 7.5 microg/ml cytochalasin B and vitrified in 6.5 M glycerol and 6% BSA (VS1) in either heat-sealed (HS) or open straws (OS). The post-thaw survival of those stored in HS was 15.4% after 24 and 48 h in vitro; storage in OS significantly improved survival (58.8% for both 24 and 48 h). When similar stage blastocysts were cultured in cytochalasin B and vitrified with 8 M ethylene glycol and 7% polyvinylpyrrolidone (PVP; VS2) in OS, survival was 44.4 and 33.3% for 24 and 48 h, respectively. Day 5 late morulae and early blastocysts were collected, cultured with cytochalasin B, and centrifuged or left intact (control), then vitrified with VS1 in HS or OS, or vitrified in VS2 in OS only. None of the intact control embryos survived thawing and 48 h culture in vitro. Centrifuged early blastocysts vitrified with VS1 showed good post-thaw survival in culture when stored in HS (62.8 and 60.5% for 24 and 48 h, respectively), or OS (75 and 63.6%). When vitrified with VS2 in OS, survival improved (80 and 76.7%). Peri-hatching blastocysts were vitrified in VS1, and early blastocysts were vitrified with VS1 and VS2. All blastocysts were stored in OS. The embryos were recovered and transferred to Day 4 and 5 pseudopregnant recipients (for Day 5 and 6 blastocysts, respectively). Of the five recipients receiving peri-hatching blastocysts, two became pregnant and delivered a total of eight piglets. All three recipients of early blastocysts vitrified in VS1 had a delayed return to estrus; while of the four receiving embryos vitrified with VS2, two were delayed in returning to estrus, and one was confirmed pregnant after 45 days. A litter of five piglets, one male and four female, was produced at 116 days of gestation. To our knowledge, this is the first litter of piglets produced from early blastocysts vitrified without micromanipulation to remove polarized lipid droplets. PMID:12141566

Beeb, L F S; Cameron, R D A; Blackshaw, A W; Higgins, A; Nottle, M B

2002-06-01

67

Beneficial effect of long zona dissection on frozen-thawed blastocysts at a young age  

Microsoft Academic Search

Aim  To assess the appropriateness of assisted hatching using long zona dissection of human frozen-thawed blastocysts at the time\\u000a of warming, especially in women over 35 years of age or with repeated implantation failures.\\u000a \\u000a \\u000a \\u000a Methods  Of 177 frozen-thawed blastocyst transfer cycles, 89 control cycles had an intact zona and 88 cycles had assisted hatching\\u000a using long zona dissection of human thawed blastocyst

Setsuko Yamamoto; Michiko Umeki; Mioko Kodoma; Teruhiro Hamano; Fujiyo Matsusita

2007-01-01

68

Epigallocatechin gallate induces embryonic toxicity in mouse blastocysts through apoptosis.  

PubMed

Abstract Catechins, a family of polyphenols found in tea, evoke various responses, including cell death. However, the side effects of these compounds, particularly those on embryonic development, have not been characterized in detail. A previous study by our group showed that (-)-epigallocatechin-3-gallate (EGCG), a catechin highly abundant in green tea, induces different cell-death modes in MCF-7 cells, depending on the treatment dosage. In the current study, we examined the effects of EGCG on mouse embryos at the blastocyst stage, subsequent embryonic attachment and outgrowth in vitro and in vivo implantation by embryo transfer. Blastocysts treated with 25-50??M of EGCG exhibited a significant increase in apoptosis and a corresponding decrease in total cell number. Notably, the implantation success rate of blastocysts pretreated with EGCG was lower than that of their control counterparts. Moreover, in vitro treatment with 25-50??M of EGCG led to increased resorption of postimplantation embryos and decreased fetal weight. EGCG appeared to induce injury in mouse blastocysts through intrinsic apoptotic signaling processes to impair sequent embryonic development. These results collectively highlight the potential of EGCG to induce embryonic cytotoxicity. PMID:24164432

Fan, Yu-Ching; Chan, Wen-Hsiung

2014-07-01

69

Embryonic toxicity of sanguinarine through apoptotic processes in mouse blastocysts.  

PubMed

In this study, we examined the cytotoxic effects of sanguinarine, a phytoalexin with antimicrobial, anti-oxidant, anti-inflammatory and pro-apoptotic effects, on the blastocyst stage of mouse embryos, subsequent embryonic attachment and outgrowth in vitro and in vivo implantation via embryo transfer. Blastocysts treated with 0.5-2 ?M sanguinarine exhibited significantly increased apoptosis and a corresponding decrease in total cell number. Notably, the implantation success rates of blastocysts pretreated with sanguinarine were lower than that of their control counterparts. Moreover, in vitro treatment with 0.5-2 ?M sanguinarine was associated with increased resorption of post-implantation embryos and decreased fetal weight. Our results collectively indicate that sanguinarine induces apoptosis and retards early post-implantation development in vitro and in vivo. In addition, sanguinarine induces apoptotic injury effects on mouse blastocysts through intrinsic and extrinsic apoptotic signaling processes to impair sequent embryonic development. However, the extent to which sanguinarine exerts teratogenic effects on early human development is not known at present, and further studies are required to establish effective protection strategies against its cytotoxic effects. PMID:21722720

Chan, Wen-Hsiung

2011-09-10

70

The dynamic structure of rabbit blastocyst coverings  

Microsoft Academic Search

The neozona is the innermost layer of the complex blastocyst coverings of the rabbit and is located between the mucoprotein layer and the trophoblast. As shown previously the neozona begins to replace the zona pellucida from the 4th day post coitum (d p.c.) on (Denker and Gerdes 1979). In the present study, rabbit blastocyst coverings were checked for regional differences

R. Leiser; H. W. Denker

1988-01-01

71

Successful Production of Piglets Derived from Expanded Blastocysts Vitrified Using a Micro Volume Air Cooling Method without Direct Exposure to Liquid Nitrogen  

PubMed Central

Abstract This study was conducted to clarify the feasibility of newly developed vitrification techniques for porcine embryos using the micro volume air cooling (MVAC) method without direct contact with liquid nitrogen (LN2). Expanded blastocysts were vitrified in a solution containing 6 M ethylene glycol, 0.6 M trehalose and 2% (wt/vol) polyethylene glycol in 10% HEPES-buffered PZM-5. The blastocysts were collected from gilts and vitrified using the new device (MVAC) or a Cryotop (CT). Blastocysts were stored in LN2 for at least 1 month. After warming, cryoprotective agents were removed using a single step. Survival of the embryos was assessed by in vitro culture (Experiment 1) and by embryo transfer to recipients (Experiment 2). In Experiment 1, the embryos vitrified by the MVAC or CT and fresh embryos without vitrification (Control) were used. The survival rates of embryos in the MVAC, CT and Control groups were 88.9% (32/36), 91.7% (33/36) and 100% (34/34), respectively, after 48 h culture, and the hatching rates of embryos after 48 h incubation were 69.4% (25/36), 63.9% (23/36) and 94.1% (32/34), respectively. In Experiment 2, 64 vitrified embryos were transferred to 5 recipient gilts, and 8 healthy piglets were produced from 3 recipients in the MVAC group. Similarly, 66 vitrified embryos were transferred to 5 recipient gilts, and 9 healthy piglets were produced from 2 recipients in the CT group. These results indicated that porcine expanded blastocysts can be cryopreserved using the MVAC method without potential pathogen contamination from LN2.

MISUMI, Koji; HIRAYAMA, Yuri; EGAWA, Sachiko; YAMASHITA, Shoko; HOSHI, Hiroyoshi; IMAI, Kei

2013-01-01

72

Blastocyst implantation failure relates to impaired translational machinery gene expression.  

PubMed

Oocyte quality is a well-established determinant of embryonic fate. However, the molecular participants and biological markers that affect and may predict adequate embryonic development are largely elusive. Our aim was to identify the components of the oocyte molecular machinery that part take in the production of a healthy embryo. For this purpose, we used an animal model, generated by us previously, the oocytes of which do not express Cx43 (Cx43(del/del)). In these mice, oogenesis appears normal, fertilisation does occur, early embryonic development is successful but implantation fails. We used magnetic resonance imaging analysis combined with histological examination to characterise the embryonic developmental incompetence. Reciprocal embryo transfer confirmed that the blastocyst evolved from the Cx43(del/del) oocyte is responsible for the implantation disorder. In order to unveil the genes, the impaired expression of which brings about the development of defective embryos, we carried out a genomic screening of both the oocytes and the resulting blastocysts. This microarray analysis revealed a low expression of Egr1, Rpl21 and Eif4a1 in Cx43(del/del) oocytes and downregulation of Rpl15 and Eif4g2 in the resulting blastocysts. We propose that global deficiencies in genes related to the expression of ribosomal proteins and translation initiation factors in apparently normal oocytes bring about accumulation of defects, which significantly compromise their developmental capacity. The blastocysts resulting from such oocytes, which grow within a confined space until implantation, may be unable to generate enough biological mass to allow their expansion. This information could be implicated to diagnosis and treatment of infertility, particularly to IVF. PMID:24700326

Plaks, Vicki; Gershon, Eran; Zeisel, Amit; Jacob-Hirsch, Jasmine; Neeman, Michal; Winterhager, Elke; Rechavi, Gideon; Domany, Eytan; Dekel, Nava

2014-07-01

73

Successful twin birth following blastocyst culture of embryos derived from the immotile ejaculated spermatozoa from a patient with primary ciliary dyskinesia: A case report  

PubMed Central

Purpose To describe the ultrastructure of spermatozoa from a patient with complete asthenozoospermia that resulted in live births following blastocyst culture. Materials and methods Analyses of spermatozoa from a 36 year old patient were performed using light and electron microscopy. The hypo-osmotic swelling test was used to select spermatozoa for intracytoplasmic sperm injection. Embryos were cultured to the blastocyst stage. Results 100% of the spermatozoa had dynein arm deficiency with secondary defects varying from 3–17%. Six oocytes were injected; five fertilized normally and one was digynic. All five zygotes formed good quality blastocysts. Three blastocysts were cryopreserved and two blastocysts were transferred. Twin females were born at 37 weeks. Conclusions The hypo-osmotic swelling test can be used to select viable immotile ejaculated spermatozoa from a patient with dynein arm deficiency and can produce excellent fertilization rates and blastocyst development resulting in live births.

Price, Robert L.; Davis, Jeffrey M.; Whitman-Elia, Gail F.

2008-01-01

74

Microtube liquid single-phase heat transfer in laminar flow  

Microsoft Academic Search

One of the main applications of microscale flow is miniature, high-efficiency heat transfer. The most simple and immediate solution to the problem of concentrated heat exchange is the use of small diameter channels with single-phase water flow, but there is a lack of publicised knowledge about the heat transfer performance in these conditions. In this article, an experimental investigation is

G. P. Celata; M. Cumo; V. Marconi; S. J. McPhail; G. Zummo

2006-01-01

75

The Graduated Embryo Score (GES) predicts blastocyst formation and pregnancy rate from cleavage-stage embryos  

Microsoft Academic Search

BACKGROUND: Embryo morphology and cleavage rates alone do not consistently identify embryos with high implantation potential following IVF. Blastocyst transfer has been reported to improve success rates by identifying potentially superior quality embryos. Algorithms for predicting IVF outcomes based on the presence of early developmental milestones have been proposed. Here we introduce the Graduated Embryo Score (GES). METHODS: Nucleolar alignment

Jeffrey D. Fisch; Herman Rodriguez; Richard Ross; Gail Overby; Geoffrey Sher

2001-01-01

76

Progesterone replacement with vaginal gel versus i.m. injection: cycle and pregnancy outcomes in IVF patients receiving vitrified blastocysts  

PubMed Central

STUDY QUESTION Does the type of luteal support affect pregnancy outcomes in recipients of vitrified blastocysts? SUMMARY ANSWER Luteal support with vaginal progesterone gel or i.m. progesterone (IMP) results in comparable implantation and pregnancy rates in IVF patients receiving vitrified blastocysts. WHAT IS KNOWN ALREADY In fresh IVF cycles, both IMP and vaginal progesterone have become the standard of care for luteal phase support. Due to conflicting data in replacement cycles, IMP is often considered to be the standard of care. STUDY DESIGN, SIZE, DURATION Retrospective analysis of 920 frozen embryo transfer (FET) cycles between 1 January 2010 and 1 September 2012. PARTICIPANTS/MATERIALS, SETTING, METHODS Patients from a large, private practice undergoing autologous and donor FET using IMP or vaginal progesterone gel for luteal support were included in the analysis. IMP was used for luteal support in 682 FET cycles and vaginal progesterone gel was used in 238 FET cycles. Standard clinical outcomes of positive serum hCG levels, implantation, clinical pregnancy, spontaneous abortion and live birth were reported. MAIN RESULTS AND THE ROLE OF CHANCE The IMP and vaginal progesterone gel groups had similar patient demographics for all characteristics assessed. Implantation rates (46.4 versus 45.6%, P = 0.81), clinical pregnancy rates (61.7 versus 60.5%, P = 0.80) and live birth rates (49.1 versus 48.9%, P > 0.99) were not significantly different between IMP and vaginal progesterone gel, respectively. LIMITATIONS, REASONS FOR CAUTION This study is limited by its retrospective design and by its lack of randomization to the type of luteal support. In addition, because no a priori expected rates of success could be provided for this retrospective investigation, it was not possible to estimate statistical power associated with the various outcomes presented. WIDER IMPLICATIONS OF THE FINDINGS With the recent trends toward single embryo transfer (SET) and use of vitrified blastocysts in FET cycles, our data with ?40% of cycles being SET and use of exclusively vitrified blastocysts are more relevant to current practices than previous studies. STUDY FUNDING/COMPETING INTEREST(S) Support for data collection and analysis was provided by Actavis, Inc. D.S. has received honoraria for lectures and participation in Scientific Advisory Boards for Actavis, Inc. J.P. is an employee of Actavis, Inc. N.E. has received payment from Actavis, Inc., for her time for data collection. H.H. has received payment from Actavis, Inc., for statistical analyses. Z.P.N. has nothing to disclose.

Shapiro, Daniel B.; Pappadakis, Jennifer A.; Ellsworth, Nancy M.; Hait, Howard I.; Nagy, Zsolt Peter

2014-01-01

77

X-Linked Gene Transcription Patterns in Female and Male In Vivo, In Vitro and Cloned Porcine Individual Blastocysts  

PubMed Central

To determine the presence of sexual dimorphic transcription and how in vitro culture environments influence X-linked gene transcription patterns in preimplantation embryos, we analyzed mRNA expression levels in in vivo-derived, in vitro-fertilized (IVF), and cloned porcine blastocysts. Our results clearly show that sex-biased expression occurred between female and male in vivo blastocysts in X-linked genes. The expression levels of XIST, G6PD, HPRT1, PGK1, and BEX1 were significantly higher in female than in male blastocysts, but ZXDA displayed higher levels in male than in female blastocysts. Although we found aberrant expression patterns for several genes in IVF and cloned blastocysts, similar sex-biased expression patterns (on average) were observed between the sexes. The transcript levels of BEX1 and XIST were upregulated and PGK1 was downregulated in both IVF and cloned blastocysts compared with in vivo counterparts. Moreover, a remarkable degree of expression heterogeneity was observed among individual cloned embryos (the level of heterogeneity was similar in both sexes) but only a small proportion of female IVF embryos exhibited variability, indicating that this phenomenon may be primarily caused by faulty reprogramming by the somatic cell nuclear transfer (SCNT) process rather than in vitro conditions. Aberrant expression patterns in cloned embryos of both sexes were not ameliorated by treatment with Scriptaid as a potent HDACi, although the blastocyst rate increased remarkably after this treatment. Taken together, these results indicate that female and male porcine blastocysts produced in vivo and in vitro transcriptional sexual dimorphisms in the selected X-linked genes and compensation of X-linked gene dosage may not occur at the blastocyst stage. Moreover, altered X-linked gene expression frequently occurred in porcine IVF and cloned embryos, indicating that X-linked gene regulation is susceptible to in vitro culture and the SCNT process, which may eventually lead to problems with embryonic or placental defects.

Park, Chi-Hun; Jeong, Young Hee; Jeong, Yeun-Ik; Lee, Se-Yeong; Jeong, Yeon-Woo; Shin, Taeyoung; Kim, Nam-Hyung; Jeung, Eui-Bae; Hyun, Sang-Hwan; Lee, Chang-Kyu; Lee, Eunsong; Hwang, Woo Suk

2012-01-01

78

Diverse roles of prostaglandins in blastocyst implantation.  

PubMed

Prostaglandins (PGs), derivatives of arachidonic acid, play an indispensable role in embryo implantation. PGs have been reported to participate in the increase in vascular permeability, stromal decidualization, blastocyst growth and development, leukocyte recruitment, embryo transport, trophoblast invasion, and extracellular matrix remodeling during implantation. Deranged PGs syntheses and actions will result in implantation failure. This review summarizes up-to-date literatures on the role of PGs in blastocyst implantation which could provide a broad perspective to guide further research in this field. PMID:24616654

Salleh, Naguib

2014-01-01

79

Cytotoxic Effects of Dillapiole on Embryonic Development of Mouse Blastocysts in Vitro and in Vivo  

PubMed Central

We examined the cytotoxic effects of dillapiole, a phenylpropanoid with antileishmanial, anti-inflammatory, antifungal, and acaricidal activities, on the blastocyst stage of mouse embryos, subsequent embryonic attachment and outgrowth in vitro, and in vivo implantation via embryo transfer. Blastocysts treated with 2.5–10 ?M dillapiole exhibited a significant increase in apoptosis and corresponding decrease in total cell number. Notably, the implantation success rates of blastocysts pretreated with dillapiole were lower than those of their control counterparts. Moreover, in vitro treatment with 2.5–10 ?M dillapiole was associated with increased resorption of post-implantation embryos and decreased fetal weight. Our results collectively indicate that dillapiole induces apoptosis and retards early post-implantation development, both in vitro and in vivo. However, the extent to which this organic compound exerts teratogenic effects on early human development is not known at present. Further studies are required to establish effective protection strategies against the cytotoxic effects of dillapiole.

Chan, Wen-Hsiung

2014-01-01

80

Blastocyst cryopreservation: ultrarapid vitrification using cryoloop technique  

Microsoft Academic Search

Human embryos have been cryopreserved mainly by slow freezing, but vitrification has also proven effective for embryos at early cleavage stages. However, clinical results on blastocyst cryopreservation have not been consistent. A feasible option appears to be ultrarapid vitrification, in which embryos are vitrified with a reduced amount of solution to achieve extremely high rates of cooling and warming. The

Tetsunori Mukaida; Katsuhiko Takahashi; Magosaburo Kasai

2003-01-01

81

Correlated Single Quantum Dot Blinking and Interfacial Electron Transfer Dynamics  

PubMed Central

The electron transfer (ET) dynamics from core/multi-shell (CdSe/CdS3MLZnCdS2MLZnS2ML) quantum dots (QDs) to adsorbed Fluorescein (F27) molecules have been studied by single particle spectroscopy to probe the relationship between single QD interfacial electron transfer and blinking dynamics. Electron transfer from the QD to F27 and the subsequent recombination were directly observed by ensemble-averaged transient absorption spectroscopy. Single QD-F27 complexes show correlated fluctuation of fluorescence intensity and lifetime, similar to those observed in free QDs. With increasing ET rate (controlled by F27-to-QD ratio), the lifetime of on states decreases and relative contribution of off states increases. It was shown that ET is active for QDs in on states, the excited state lifetime of which reflects the ET rate, whereas in the off state QD excitons decay by Auger relaxation and ET is not a competitive quenching pathway. Thus, the blinking dynamics of single QDs modulate their interfacial ET activity. Furthermore, interfacial ET provides an additional pathway for generating off states, leading to correlated single QD interfacial ET and blinking dynamics in QD-acceptor complexes. Because blinking is a general phenomenon of single QDs, it appears that the correlated interfacial ET and blinking and the resulting intermittent ET activity are general phenomena for single QDs.

Jin, Shengye; Hsiang, Jung-Cheng; Zhu, Haiming; Song, Nianhui; Dickson, Robert M.; Lian, Tianquan

2011-01-01

82

Correlated Single Quantum Dot Blinking and Interfacial Electron Transfer Dynamics.  

PubMed

The electron transfer (ET) dynamics from core/multi-shell (CdSe/CdS(3ML)ZnCdS(2ML)ZnS(2ML)) quantum dots (QDs) to adsorbed Fluorescein (F27) molecules have been studied by single particle spectroscopy to probe the relationship between single QD interfacial electron transfer and blinking dynamics. Electron transfer from the QD to F27 and the subsequent recombination were directly observed by ensemble-averaged transient absorption spectroscopy. Single QD-F27 complexes show correlated fluctuation of fluorescence intensity and lifetime, similar to those observed in free QDs. With increasing ET rate (controlled by F27-to-QD ratio), the lifetime of on states decreases and relative contribution of off states increases. It was shown that ET is active for QDs in on states, the excited state lifetime of which reflects the ET rate, whereas in the off state QD excitons decay by Auger relaxation and ET is not a competitive quenching pathway. Thus, the blinking dynamics of single QDs modulate their interfacial ET activity. Furthermore, interfacial ET provides an additional pathway for generating off states, leading to correlated single QD interfacial ET and blinking dynamics in QD-acceptor complexes. Because blinking is a general phenomenon of single QDs, it appears that the correlated interfacial ET and blinking and the resulting intermittent ET activity are general phenomena for single QDs. PMID:21915369

Jin, Shengye; Hsiang, Jung-Cheng; Zhu, Haiming; Song, Nianhui; Dickson, Robert M; Lian, Tianquan

2010-08-31

83

Vitrification of in vitro produced bovine blastocysts: methodological studies and developmental capacity.  

PubMed

Methodological studies were undertaken to test the validity of a three-step vitrification procedure for bovine in vitro produced embryos using glycerol and ethylene glycol as cryoprotectants. Embryos were produced in a low-phosphate culture system (medium VT1 + 10% foetal calf serum) and vitrified at day 7 post-insemination either in a mixture of 25% glycerol--25% ethylene glycol or a mixture of 10% glycerol--40% ethylene glycol. In the first mixture 67% (n = 283) of blastocysts were re-expanded after 72 h of culture and 53% were hatched while in the second one (n = 65) only 5% survived. The mean number of cells of the surviving blastocysts was correlated with the rate of survival (R2 = 0.47; P = 0.0024). Embryo size (diameter < or > to 180 microm) did not influence blastocyst survival or cell number, but hatching rate was higher for embryos > 180 microm. Embryo survival, hatching rate and cell number 72 h post-warming were not affected by the mode of vitrification (direct plunging into nitrogen liquid or vitrification into nitrogen liquid vapour), the mode of preparation of the vitrification solutions (molar or molal basis) or by the concentration of galactose used as a diluent (0 to 0.85 M). Only one calf was born after transfer of 22 vitrified blastocysts. These results confirm the apparent lack of correlation for cryopreserved embryos between in vitro survival or hatching and viability after transfer. PMID:9776482

Donnay, I; Auquier, P; Kaidi, S; Carolan, C; Lonergan, P; Mermillod, P; Massip, A

1998-08-21

84

Intermittent Single-Molecule Interfacial Electron Transfer Dynamics  

SciTech Connect

We report on single molecule studies of photosensitized interfacial electron transfer (ET) processes in Coumarin 343 (C343)-TiO2 nanoparticle (NP) and Cresyl Violet (CV+)-TiO2 NP systems, using time-correlated single photon counting coupled with scanning confocal fluorescence microscopy. Fluorescence intensity trajectories of individual dye molecules adsorbed on a semiconductor NP surface showed fluorescence fluctuations and blinking, with time constrants distributed from sub-milliseconds to several seconds.

Biju, Vasudevan P.; Micic, Miodrag; Hu, Dehong; Lu, H. Peter

2004-08-04

85

The Effect of Biopsy During Precompacted Morula Stage on Post Vitrification Development of Blastocyst Derived Bovine Embryos  

PubMed Central

Improvements on embryo micromanipulation techniques led to the use of embryo biopsy in commercial embryo transfer programs for genetic analysis of preimplantation bovine embryos. The aim of this study was to evaluate the quality of bovine blastocyst derived from embryos biopsied at different pre-compacted morulae stages by assessment of cryosurvivability of the resulting blastocysts. The in vitro produced bovine embryos were subjected to biopsy at days 2, 3, and 4 post-insemination with different cell numbers (4 to 16-cells). Embryo cell biopsy was carried out in a 100 µl drop of H-SOF following pronase drilling by aspiration of one blastomere. The biopsied embryos were then cultured in SOFaaBSA co-cultured with oviduct cells-monolayer until blastocyst formation. The blastocysts were cryopreserved at room temperature after exposure of equilibration (glycerol 1.4 M for 5 min and then glycerol 1.4 M and ethylene glycol 3.6 M for 5 min) and vitrification solutions (3.4 M glycerol and 4.6 M ethylene glycol). The blastocysts were loaded into the center of 0.25 ml straws separated by air bubbles from 2 columns of sucrose 0.5 M and plunged immediately into liquid nitrogen. There was no significant difference in cryosurvivability of vitrified-warmed blastocysts derived form biopsied embryos at different pre-compacted morula stages. The quality of biopsy derived blastocysts was identical to that of non-biopsy derived ones in terms of post vitrifcation survival and hatching rates. In conclusion there was no preference between different times of embryo biopsy at precompacted morula stages in term of cryosurvivability of biopsy derived bovine blastocysts.

Shirazi, Abolfazl; Borjian, Sara; Ahmadi, Ebrahim; Nazari, Hassan; Heidari, Banafsheh

2010-01-01

86

Conformational effect on energy transfer in single polythiophene chains.  

PubMed

Herein we describe the use of regioregular (rr-) and regiorandom (rra-) P3HT as models to study energy transfer in ordered and disordered single conjugated polymer chains. Single molecule fluorescence spectra and excitation/emission polarization measurements were compared with a Förster resonance energy transfer (FRET) model simulation. An increase in the mean single chain polarization anisotropy from excitation to emission was observed for both rr- and rra-P3HT. The peak emission wavelengths of rr-P3HT were at substantially lower energies than those of rra-P3HT. A simulation based on FRET in single polymer chain conformations successfully reproduced the experimental observations. These studies showed that ordered conformations facilitated efficient energy transfer to a small number of low-energy sites compared to disordered conformations. As a result, the histograms of spectral peak wavelengths for ordered conformations were centered at much lower energies than those obtained for disordered conformations. Collectively, these experimental and simulated results provide the basis for quantitatively describing energy transfer in an important class of conjugated polymers commonly used in a variety of organic electronics applications. PMID:22780709

Adachi, Takuji; Lakhwani, Girish; Traub, Matthew C; Ono, Robert J; Bielawski, Christopher W; Barbara, Paul F; Vanden Bout, David A

2012-08-16

87

Single-molecule spectroscopy of interfacial electron transfer.  

PubMed

It is widely appreciated that single-molecule spectroscopy (SMS) can be used to measure properties of individual molecules which would normally be obscured in an ensemble-averaged measurement. In this report we show how SMS can be used to measure photoinduced interfacial electron transfer (IET) and back electron transfer rates in a prototypical chromophore-bridge-electrode nonadiabatic electron transfer system. N-(1-hexylheptyl)-N'-(12-carboxylicdodecyl)perylene-3,4,9,10-tetracarboxylbisimide was synthesized and incorporated into mixed self-assembled monolayers (SAMs) on an ITO (tin-doped indium oxide, a p-type semiconductor) electrode. Single-molecule fluorescence time trajectories from this system reveals "blinks", momentary losses in fluorescence (>20 ms to seconds in duration), which are attributed to discrete electron transfer events: electron injection from the perylene chromophore into the conduction band of the ITO leads to the loss of fluorescence, and charge recombination (back electron transfer) leads to the return of fluorescence. Such blinks are not observed when an electrode is not present. The fluorescence trajectories were analyzed to obtain the forward and back electron rates; the measured rates are found to lie in the millisecond to second regime. Different rates are observed for different molecules, but the lifetime distributions for the forward or back electron transfer for any given molecule are well fit by single exponential kinetics. The methodology used is applicable to a wide variety of systems and can be used to study the effects of distance, orientation, linker, environment, etc. on electron transfer rates. The results and methodology have implications for molecular electronics, where understanding and controlling the range of possible behaviors inherent to molecular systems will likely be as important as understanding the individual behavior of any given molecule. PMID:14531709

Holman, Michael W; Liu, Ruchuan; Adams, David M

2003-10-15

88

Making the blastocyst: lessons from the mouse  

PubMed Central

Mammalian preimplantation development, which is the period extending from fertilization to implantation, results in the formation of a blastocyst with three distinct cell lineages. Only one of these lineages, the epiblast, contributes to the embryo itself, while the other two lineages, the trophectoderm and the primitive endoderm, become extra-embryonic tissues. Significant gains have been made in our understanding of the major events of mouse preimplantation development, and recent discoveries have shed new light on the establishment of the three blastocyst lineages. What is less clear, however, is how closely human preimplantation development mimics that in the mouse. A greater understanding of the similarities and differences between mouse and human preimplantation development has implications for improving assisted reproductive technologies and for deriving human embryonic stem cells.

Cockburn, Katie; Rossant, Janet

2010-01-01

89

Quantity and infectivity of embryo-associated bovine viral diarrhea virus and antiviral influence of a blastocyst impede in vitro infection of uterine tubal cells.  

PubMed

In previous studies, bovine viral diarrhea virus (BVDV) remained associated with IVF embryos after viral exposure and washing. However, uterine tubal cells (UTC) were not infected when exposed embryos were washed and individually co-cultured with them. The objective of this study was to evaluate quantity and infectivity of embryo-associated virus and antiviral influence of a blastocyst as possible explanations for failure to infect the UTC in vitro. Morulae and blastocysts were produced in vitro and washed. A portion of the embryos were incubated for 2 h in medium containing 10(6) to 10(8) cell culture infective doses (50%, CCID50) of a genotype I, noncytopathic BVDV per milliliter and then washed again. Virus isolation was attempted on sonicated negative (virus unexposed) and positive (virus exposed) control embryo groups after washing. The influence of quantity and infectivity of embryo-associated virus was evaluated by transferring exposed, washed embryo groups (2, 5, and 10 embryos/group) or sonicate fluid of exposed, washed, sonicated embryo groups (2, 5, and 10 embryos/group) to cultures containing bovine UTC in IVC medium that was free of BVDV neutralizing activity. The antiviral influence of an embryo was evaluated by adding 1 to 10(5) CCID50 of BVDV to UTC in the presence or absence of a single unexposed blastocyst in IVC medium. After 2 d in co-culture, the UTC, IVC medium and washed embryos (when present) were tested separately for the presence of BVDV using virus isolation. Virus was isolated from sonicate fluids of all positive but no negative controls. Virus was not isolated from any UTC following 2 d of culture with virally exposed groups of intact embryos. However, virus was isolated from UTC cultured with sonicate fluids from some groups of 5 (60%) and 10 (40%) embryos. Infective virus also remained associated with some groups of 2 (20%), 5 (40%) and 10 (60%) intact embryos after 48 h of post-exposure culture. Finally, primary cultures of UTC were more susceptible to infection with BVDV in the absence of a blastocyst (P = 0.01). Results indicate that insufficient quantity and reduced infectivity of embryo-associated virus as well as an antiviral influence of intact IVF blastocysts may all contribute to failure of embryo-associated virus to infect UTC in vitro. PMID:10735128

Givens, M D; Galik, P K; Riddell, K P; Brock, K V; Stringfellow, D A

1999-10-01

90

Cryopreservation of bovine blastocysts obtained by intracytoplasmic sperm injection  

Microsoft Academic Search

The freezability and survivability of zona-intact and zona-free (hatched) bovine blastocysts obtained by intracytoplasmic sperm injection (ICSI) were assessed. Day 7 or 8 blastocysts were cryopreserved by slow freezing using 1.5 M glycerol and 0.2 M sucrose. Embryos were exposed to solutions in a 2-step procedure at room temperature and frozen in a programmed cell freezer. Blastocysts that re-expanded within

L. Keskintepe; B. G. Brackett

2000-01-01

91

Single-Phase Heat Transfer and Fluid Flow in Micropipes  

Microsoft Academic Search

The objective of this paper is to provide a general overview of the research carried out so far in single-phase heat transfer and flow in capillary (micro) pipes. Laminar flow and laminar-to-turbulent flow transition are analyzed in detail in order to clarify the discrepancies among the results obtained by different researchers. Experiments performed in the ENEA laboratory indicate that in

GIAN PIERO CELATA

2004-01-01

92

Spin-transfer torque in a single ferromagnet  

NASA Astrophysics Data System (ADS)

A spin polarized current, with sufficiently high current density, is able to switch a magnet or induce magnetization precession. This is the consequence of the ¡°spin-transfer torque¡+/- that originates from spin angular momentum transfer between conduction electrons and the magnetization. Previously most theories and experiments explore F/N/F trilayer and F/N multilayer structures, where F denotes a ferromagnet and N denotes a nonmagnetic metal. These structures have been generally presumed indispensable, since non-collinear magnetizations between a polarizing layer and a free layer are required to generate spin torques, and the GMR effect is essential in detecting magnetization variations. In this work, spin-transfer torque effects in a single ferromagnetic layer are demonstrated, using current injection through a point-contact at 4.2 K. Firstly, differential resistance peaks, generally regarded as signatures of spin-wave excitations, are observed in a single ferromagnetic layer in high magnetic fields [1]. The current values corresponding to the peak positions linearly depend on the external field in the range of 2 to 9 Tesla. Secondly, hysteretic current-induced switching is observed in a single ferromagnet in low magnetic fields. Both experiments can be interpreted by a simple model based on heterogeneous current distribution and domain wall scattering. Systematic variations between low field and high field regions have been investigated and the implications will be discussed. [1] Y. Ji, C. L. Chien and M. D. Stiles, Phys. Rev. Lett. 90, 106601 (2003)

Ji, Yi

2004-03-01

93

Successful pregnancy following replacement of embryos previously refrozen at blastocyst stage  

Microsoft Academic Search

We present the first reported clinical pregnancy following transfer of embryos that had been subjected to two freeze-thaw cycles: the first at day 3 after insemination, and the second after culturing to the blastocyst stage. A 25-year-old woman undergoing IVF treatment for male factor infertility opted for intracytoplasmic sperm injection (ICSI). ICSI treatment resulted in the successful production of 19

Murshid Farhat; Bat-Sheva Zentner; Francine Lossos; Yuval Bdolah; Hananel Holtzer; Arye Hurwitz

94

Rho-associated kinase activity is required for proper morphogenesis of the inner cell mass in the mouse blastocyst.  

PubMed

The blastocyst consists of the outer layer of trophectoderm and pluripotent inner cell mass (ICM), the precursor of the placenta and fetus, respectively. During blastocyst expansion, the ICM adopts a compact, ovoidal shape, whose proper morphology is crucial for normal embryogenesis. Rho-associated kinase (ROCK), an effector of small GTPase RHO signaling, mediates the diverse cellular processes of morphogenesis, but its role in ICM morphogenesis is unclear. Here, we demonstrate that ROCK is required for cohesion of ICM cells and formation of segregated tissues called primitive endoderm (PrE) and epiblast (Epi) in the ICM of the mouse blastocyst. Blastocyst treatment with ROCK inhibitors Y-27632 and Fasudil caused widening or spreading of the ICM, and intermingling of PrE and Epi. Widening of ICM was independent of trophectoderm because isolated ICMs as well as colonies of mouse embryonic stem cells (mESC) also spread upon Y-27632 treatment. PrE, Epi, and trophectoderm cell numbers were similar between control and treated blastocysts, suggesting that ROCK inhibition affected ICM morphology but not lineage differentiation. Rock1 and Rock2 knockdown via RNA interference in mESC also induced spreading, supporting the conclusion that morphological defects caused by the pharmacological inhibitors were due to ROCK inactivation. When blastocysts were transferred into surrogates, implantation efficiencies were unaffected by ROCK inhibition, but treated blastocysts yielded greater fetal loss. These results show that proper ICM morphology is dependent on ROCK activity and is crucial for fetal development. Our studies have wider implication for improving efficiencies of human assisted reproductive technologies that diminish pregnancy loss and promote successful births. PMID:23946538

Laeno, Arlene May A; Tamashiro, Dana Ann A; Alarcon, Vernadeth B

2013-11-01

95

Conformation and energy transfer in single conjugated polymers.  

PubMed

In contrast to the detailed understanding of inorganic materials, researchers lack a comprehensive view of how the properties of bulk organic materials arise from their individual components. For conjugated polymers to eventually serve as low cost semiconductor layers in electronic devices, researchers need to better understand their functionality. For organics, traditional materials science measurements tend to destroy the species of interest, especially at low concentrations. However, fluorescence continues to be a remarkably flexible, relatively noninvasive tool for probing the properties of individual molecules and allows researchers to carry out a broad range of experiments based on a relatively simple concept. In addition, the sensitivity of single-molecule spectroscopy allows researchers to see the properties of an individual component that would be masked in the bulk phase. In this Account, we examine several photophysical properties of different conjugated polymers using single-molecule spectroscopy. In these experiments, we probed the relationship between the conformation of single conjugated polymer chains and the distance scale and efficiency of energy transfer within the polymer. Recent studies used polarization anisotropy measurements on single polymer chains to study chain folding following spin-casting from solution. This Account summarizes the effects of monomer regioregularity and backbone rigidity, by comparing a regiorandom phenylene vinylene (MEH-PPV) with both a regiorandom and regioregular thiophene (P3HT). Synthesis of novel polymers allowed us to explore the role of different conformation-directing inclusions in a PPV backbone. We showed that these inclusions control the conformation of individual chains and that molecular dynamics can predict these structural effects. In situ solvent vapor annealing studies explored the dynamics of polymer chains as well as the effect of solvent evaporation on the structural equilibrium of the polymer. We observed that a slower rate of solvent evaporation results in a narrow population of highly ordered polymer chains. These highly ordered single chains serve as a model system to probe the effect of conformation on energy transfer following excitation in single MEH-PPV polymer chains in two distinct experiments. In the first, we correlated the anisotropy of the fluorescence emission of individual chains with the anisotropy of their fluorescence excitation. Using this data, we derived a model for energy transfer in a conjugated polymer, simulating chromophores along a chain, coupled via Förster energy transfer. In the second experiment, super-resolution measurements demonstrated the ability of single-molecule spectroscopy to directly visualize energy transfer along a polymer chain embedded in a model device environment. A capacitive device allowed for controlled localization of hole polarons onto the polymer chain. These positive charges subsequently quenched local excitations, providing insight into the range of energy transfer in these single polymer molecules. As researchers continue to characterize conjugated polymer films and develop methods for creating multichain systems, single-molecule techniques will provide a greater understanding of how polymer morphology influences interchain interactions and will lead to a richer description of the electronic properties of bulk conjugated polymer films. PMID:22775295

Bolinger, Joshua C; Traub, Matthew C; Brazard, Johanna; Adachi, Takuji; Barbara, Paul F; Vanden Bout, David A

2012-11-20

96

Blastocyst rate of in vitro embryo production in sheep is affected by season.  

PubMed

Summary It has been reported that the number and quality of in vitro produced embryos is season related. This study was conducted to assess the effect of season on cleavage, blastocyst and lambing rates of in vitro produced ovine embryos during 3 years of collection data. Ovaries of Sarda sheep were collected from a slaughterhouse. In total, 5035 oocytes were recovered and matured in TCM-199 with 4 mg/ml bovine serum albumin (BSA), 100 ?M cysteamine, 0.3 mM Na pyruvate, 0.1 UI/ml recombinant follicle-stimulating hormone (r-FSH), 0.1 UI/ml recombinant luteinising hormone (r-LH), and 1 ?g/ml estradiol-17?. Matured oocytes were fertilized with fresh semen in synthetic oviductal fluid (SOF) with 20% heat inactivated estrous sheep serum. The presumptive zygotes were cultured for 6-7 days (blastocyst stage) in SOF medium supplemented with 1% Basel Medium Eagle (BME), 1% Minimum Essential Medium, 1 mM glutamine and 8 mg/ml fatty acid-free BSA. The embryos produced were vitrified and a total of 165 blastocysts (80 from the breeding season and 85 from the anoestrous season) were transferred in pairs into recipient ewes during the reproductive period. There were no significant differences in cleavage rates between seasons in any of the 3 years examined (84% versus 83%, 81% versus 80% and 80% versus 79%, respectively). The blastocyst rate varied significantly between seasons in 2005 and 2007 (P < 0.05), and in 2006 (P < 0.001). There were no differences in pregnancy and lambing rates between embryos during anoestrous versus during the breeding season. In conclusion, only the blastocyst rate appeared to have been affected by season, possibly due to variation in the number of developmentally competent oocytes. PMID:23458093

Mara, L; Sanna, D; Casu, S; Dattena, M; Muñoz, I M Mayorga

2014-08-01

97

Selective polarization transfer using a single rf field.  

PubMed

NMR is a popular and mature technique used in fields as diverse as chemistry, biology, or material science. One reason for this versatility lies in its ability to correlate the nuclei that are present in one molecule to another. This provides the researcher with correlation maps allowing for studies of the molecules at an atomic level. Selective experiments allow isolation of one such correlation to focus on spins of interest. This leads to a savings in precious experimental time by reducing the dimension of the experiment, which in turn may enable one to record more elaborate experiments that would otherwise not be amenable within reasonable acquisition times. Here, we present an alternative method to selectively transfer magnetization using a single rf field. This technique, which we call single field polarization transfer, allows to obtain longitudinal two-spin order of two scalar-coupled spins when only one of them is irradiated. The method is easy to implement and does not depend on stringent conditions, such as Hartmann-Hahn matching for selective cross-polarization transfers or very long inversion pulses and identification of coupling satellites in selective population inversion experiments. PMID:18624480

Rey Castellanos, Eddy R; Frueh, Dominique P; Wist, Julien

2008-07-01

98

Single Molecule Studies of Energy Transfer in Semiconductor Nanocrystal Clusters  

NASA Astrophysics Data System (ADS)

Enhanced fluorescence intermittency has been reported in single molecule fluorescence experiments on small clusters of semiconductor nanocrystals^1 (NCs). We report here on studies of small clusters of NCs by single molecule time-correlated single photon counting. According to this analysis, clusters typically blink on a microsecond to millisecond time scale; whereas, isolated NCs blink on a much longer millisecond to second time scale. A fast-decay component in the cluster fluorescence lifetime, not present in single NCs, is correlated with low fluorescence intensity. A model based on nonradiative energy transfer to NCs with smaller bandgap, combined with independent blinking for the NCs in the cluster, accounts for the main experimental features. In this model the smallest-gap NC dominates the emission properties, in particular the ``off'' time distribution of the cluster, which experimentally resembles that for a single NC. [1] Yu, M. and A. Van Orden, Enhanced Fluorescence Intermittency of CdSe-ZnS Quantum-Dot Cluster, Physical Review Letters, 2006 237402-4

Shepherd, Douglas; Whitcomb, Kevin; Goodwin, Peter; Gelfand, Martin; van Orden, Alan

2010-03-01

99

Evaluation of possible criteria for elective single embryo transfer  

Microsoft Academic Search

Purpose  A major problem of assisted reproductive technology (ART) is multiple gestation, which impacts neonatal and perinatal medicine.\\u000a The literature contains a number of reports that elective single embryo transfer (eSET) is effective for the control of multiple\\u000a pregnancies; however, to date, uniform criteria have not been established.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Using logistic regression analysis based on the results of ART in our department

Wataru Sato; Jun Fukuda; Kyoko Kanamori; Kazuhiro Kawamura; Jin Kumagai; Hideya Kodama; Toshinobu Tanaka

2010-01-01

100

Promotion of Human Early Embryonic Development and Blastocyst Outgrowth In Vitro Using Autocrine/Paracrine Growth Factors  

PubMed Central

Studies using animal models demonstrated the importance of autocrine/paracrine factors secreted by preimplantation embryos and reproductive tracts for embryonic development and implantation. Although in vitro fertilization-embryo transfer (IVF-ET) is an established procedure, there is no evidence that present culture conditions are optimal for human early embryonic development. In this study, key polypeptide ligands known to be important for early embryonic development in animal models were tested for their ability to improve human early embryo development and blastocyst outgrowth in vitro. We confirmed the expression of key ligand/receptor pairs in cleavage embryos derived from discarded human tri-pronuclear zygotes and in human endometrium. Combined treatment with key embryonic growth factors (brain-derived neurotrophic factor, colony-stimulating factor, epidermal growth factor, granulocyte macrophage colony-stimulating factor, insulin-like growth factor-1, glial cell-line derived neurotrophic factor, and artemin) in serum-free media promoted >2.5-fold the development of tri-pronuclear zygotes to blastocysts. For normally fertilized embryos, day 3 surplus embryos cultured individually with the key growth factors showed >3-fold increases in the development of 6–8 cell stage embryos to blastocysts and >7-fold increase in the proportion of high quality blastocysts based on Gardner’s criteria. Growth factor treatment also led to a 2-fold promotion of blastocyst outgrowth in vitro when day 7 surplus hatching blastocysts were used. When failed-to-be-fertilized oocytes were used to perform somatic cell nuclear transfer (SCNT) using fibroblasts as donor karyoplasts, inclusion of growth factors increased the progression of reconstructed SCNT embryos to >4-cell stage embryos. Growth factor supplementation of serum-free cultures could promote optimal early embryonic development and implantation in IVF-ET and SCNT procedures. This approach is valuable for infertility treatment and future derivation of patient-specific embryonic stem cells.

Cheng, Yuan; Qiao, Jie; Behr, Barry; Pera, Renee A. Reijo.; Hsueh, Aaron J. W.

2012-01-01

101

Promotion of human early embryonic development and blastocyst outgrowth in vitro using autocrine/paracrine growth factors.  

PubMed

Studies using animal models demonstrated the importance of autocrine/paracrine factors secreted by preimplantation embryos and reproductive tracts for embryonic development and implantation. Although in vitro fertilization-embryo transfer (IVF-ET) is an established procedure, there is no evidence that present culture conditions are optimal for human early embryonic development. In this study, key polypeptide ligands known to be important for early embryonic development in animal models were tested for their ability to improve human early embryo development and blastocyst outgrowth in vitro. We confirmed the expression of key ligand/receptor pairs in cleavage embryos derived from discarded human tri-pronuclear zygotes and in human endometrium. Combined treatment with key embryonic growth factors (brain-derived neurotrophic factor, colony-stimulating factor, epidermal growth factor, granulocyte macrophage colony-stimulating factor, insulin-like growth factor-1, glial cell-line derived neurotrophic factor, and artemin) in serum-free media promoted >2.5-fold the development of tri-pronuclear zygotes to blastocysts. For normally fertilized embryos, day 3 surplus embryos cultured individually with the key growth factors showed >3-fold increases in the development of 6-8 cell stage embryos to blastocysts and >7-fold increase in the proportion of high quality blastocysts based on Gardner's criteria. Growth factor treatment also led to a 2-fold promotion of blastocyst outgrowth in vitro when day 7 surplus hatching blastocysts were used. When failed-to-be-fertilized oocytes were used to perform somatic cell nuclear transfer (SCNT) using fibroblasts as donor karyoplasts, inclusion of growth factors increased the progression of reconstructed SCNT embryos to >4-cell stage embryos. Growth factor supplementation of serum-free cultures could promote optimal early embryonic development and implantation in IVF-ET and SCNT procedures. This approach is valuable for infertility treatment and future derivation of patient-specific embryonic stem cells. PMID:23152897

Kawamura, Kazuhiro; Chen, Yuan; Shu, Yimin; Cheng, Yuan; Qiao, Jie; Behr, Barry; Pera, Renee A Reijo; Hsueh, Aaron J W

2012-01-01

102

Laser-assisted hatching improves clinical outcomes of vitrified-warmed blastocysts developed from low-grade cleavage-stage embryos: a prospective randomized study.  

PubMed

The aim of this study was to evaluate the effects of quarter zona-pellucida (ZP) opening by laser-assisted hatching (QLAH) on the clinical outcomes following transfer of vitrified-warmed blastocysts developed from low-grade cleavage-stage embryos in patients with all high-grade and fair-grade cleavage-stage embryos transferred without achieving pregnancy. Patients were randomized into two groups: QLAH (n=101) and control (n=102). The implantation and clinical pregnancy rates were significantly higher in the QLAH group compared with the control group (P=0.021 and P=0.034, respectively). The live birth rate of the QLAH group was also higher, although not significantly. When the clinical outcomes according to the day of blastocyst vitrification were compared between the groups, the implantation, clinical pregnancy and live birth rates of the QLAH group were significantly higher (P<0.05) than those of the control group for day 6 blastocysts, but not for day 5 or day 5/day 6 blastocysts. These results suggest that QLAH improves the clinical outcomes of vitrified-warmed blastocysts, especially of day 6 vitrified blastocysts, developed from low-grade cleavage-stage embryos. PMID:24631166

Wan, Cai-Yun; Song, Cheng; Diao, Liang-Hui; Li, Guan-Gui; Bao, Zhong-Jian; Hu, Xiao-Dong; Zhang, Hong-Zhan; Zeng, Yong

2014-05-01

103

Individual demands of human embryos on IVF culture medium: influence on blastocyst development and pregnancy outcome.  

PubMed

The elucidation of the metabolic requirements of human embryos in vivo or in vitro remains, despite being intensively investigated, a work in progress. The adoption of extended embryo culture to the blastocyst stage during the last decade has entailed new challenges. With the increased attention to culture media formulations, more evidence on the sensitivity of embryos to their early environmental conditions is accumulating which might affect phenotype and developmental potential. A retrospective study was conducted that comprised 286 IVF cycles to evaluate the effect of two different culture media on blastocyst development and pregnancy outcome. Embryos were either cultured in a one step or a sequential medium. Higher fertilization rates and augmented blastocyst rates as well as higher implantation rates were observed when embryos were cultured in one step medium (P<0.05). Interestingly, the transfer of two embryos where one embryo was cultured in either medium resulted in a significantly higher rate of twin pregnancies. Although multiple pregnancies should be avoided in assisted reproduction treatment to reduce risks for offspring and mother, this higher frequency of twin pregnancies resulting from the transfer of embryos derived from different culture media suggests that each embryo makes individual demands on its early environment. PMID:21050820

Wirleitner, B; Vanderzwalmen, P; Stecher, A; Zech, M H; Zintz, M; Zech, N H

2010-12-01

104

Quality of porcine blastocysts produced in vitro in the presence of absence of GH  

Microsoft Academic Search

GH receptor (GHR) mRNA is expressed in bovine in vitro produced embryos up to the blastocyst stage and GH improves the quality of bovine embryos by increasing blastocyst cell numbers and reducing the incidence of apoptosis as evaluated by DNA strand-break labelling. Porcine in vitro produced blastocysts have lower cell numbers than in vivo blastocysts and exhibit higher incidences of

A. Kidson; F. J. Rubio-Pomar; Knegsel van A; Tol van H. T. A; W. Hazeleger; D. W. B. Ducro-Steverink; B. Colenbrander; S. J. Dieleman; M. M. Bevers

2004-01-01

105

Cumulative impact of adding frozen–thawed cycles to single versus double fresh embryo transfers  

Microsoft Academic Search

Randomized control trials have shown that single embryo transfer (SET) results in lower live birth rates than double embryo transfer (DET), while observational, retrospective studies find no decrease in overall live birth rate when using a SET policy. The cumulative (fresh transfer followed by frozen–thawed transfers of embryos from the same stimulated cycle) live birth rate after the first and

Kersti Lundin; Christina Bergh

2007-01-01

106

Effects of serum-free in vitro maturation of bovine oocytes on subsequent embryo development and cell allocation in two developmental stages of day 7 blastocysts.  

PubMed

Maturation of oocytes and the subsequent outcome of the in vitro production (IVP) are affected by the composition of in vitro maturation (IVM) medium. To determine the use of serum interfering with effects of single molecules, we aimed at developing simplified IVM medium. The experimental IVM media were: (1) M199-medium supplemented with hormones and serum (control), (2) as 1 but serum was substituted with fatty acid-free serum albumin (FAFBSA) and (3) M199-medium without hormonal and serum supplementation (M199). The quality of embryos was assessed on day 7 by morphology and cryotolerance, as well as by Terminal deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) and differential staining. Results showed that the nuclear maturation was suppressed in M199 group alone. Embryo cleavage and development rates, and the proportion of quality 1 blastocysts were lower in the FAFBSA and M199 groups compared to the control. Differences in the cell allocation of fresh embryos were observed at the blastocyst stage, but not at the expanded blastocyst stage. The control group blastocysts had larger number of cells allocated to the inner cell mass (ICM), and the FAFBSA group blastocysts larger apoptotic cell proportion compared to the blastocysts derived from other groups. After cryopreservation, the reduction of ICM proportion and increase of apoptotic cell proportion of embryos were equal between the experimental groups. In conclusion, exclusion of serum from the IVM media reduces embryo development and may cause perturbations in blastocyst development. Differences in the cell allocation of blastocysts between IVM media may appear only when the developmental stages are taken into account. PMID:19144013

Korhonen, K; Kananen, K; Ketoja, E; Matomäki, J; Halmekytö, M; Peippo, J

2010-02-01

107

Controlling energy transfer between multiple dopants within a single nanoparticle  

PubMed Central

Complex core-shell architectures are implemented within LaF3 nanoparticles to allow for a tailored degree of energy transfer (ET) between different rare earth dopants. By constraining specific dopants to individual shells, their relative distance to one another can be carefully controlled. Core-shell LaF3 nanoparticles doped with Tb3+ and Eu3+ and consisting of up to four layers were synthesized with an outer diameter of ?10 nm. It is found that by varying the thicknesses of an undoped layer between a Tb3+-doped layer and a Eu3+-doped layer, the degree of ET can be engineered to allow for zero, partial, or total ET from a donor ion to an acceptor ion. More specifically, the ratio of the intensities of the 541-nm Tb3+ and 590 nm Eu3+ peaks was tailored from <0.2 to ?2.4 without changing the overall composition of the particles but only by changing the internal structure. Further, the emission spectrum of a blend of singly doped nanoparticles is shown to be equivalent to the spectra of co-doped particles when a core-shell configuration that restricts ET is used. Beyond simply controlling ET, which can be limiting when designing materials for optical applications, this approach can be used to obtain truly engineered spectral features from nanoparticles and composites made from them. Further, it allows for a single excitation source to yield multiple discrete emissions from numerous lanthanide dopants that heretofore would have been quenched in a more conventional active optical material.

DiMaio, Jeffrey R.; Sabatier, Clement; Kokuoz, Baris; Ballato, John

2008-01-01

108

Identification of four genes required for mammalian blastocyst formation.  

PubMed

Summary RNA transcription, processing and translation are fundamental molecular processes required for development, growth and cell viability. Towards the functional annotation of the genome, we are engaged in a reverse genetic screen using mammalian preimplantation embryos as a model system. Here we report the essential function of four RNA processing/splicing factors (Sf3b14, Sf3b1, Rpl7l1, and Rrp7a) and show that each of these genes is required for blastocyst formation in the mouse. As very little information is known about these genes, we characterized their normal expression and localization in mouse embryos as well as phenotypic analysis of loss of function during preimplantation development. Functional knockdown of each gene product results in normal morula development but there is failure to form a blastocoel cavity or morphologically differentiated trophectoderm. We show that zygotic genome activation does occur as well as initial lineage specification in the absence of each factor. Consistent with a role in RNA splicing, we demonstrate that the absence of Sf3b14 and Sf3b1 in 8-cell and morula-stage embryos results in a specific reduction of intron containing transcripts, but no reduction single-exon genes. Taken together, we show critical developmental and molecular requirements of Sf3b14, Sf3b1, Rpl7l1, and Rrp7a during mammalian preimplantation. PMID:23211737

Maserati, Marc; Dai, Xiangpeng; Walentuk, Melanie; Mager, Jesse

2014-08-01

109

Single-element Electron-transfer Optical Detector System  

NASA Technical Reports Server (NTRS)

An optical detector system includes an electrically resistive screen that is substantially transparent to radiation energy having a wavelength of interest. An electron transfer element (e.g., a low work function photoactive material or a carbon nanotube (CNT)-based element) has a first end and a second end with its first end spaced apart from the screen by an evacuated gap. When radiation energy passes through the screen with a bias voltage being applied thereto, transfer of electrons through the electron transfer element is induced from its first to its second end such that a quantity indicative of the electrons transferred can be detected.

Jordan, Jeffrey D. (Inventor)

2004-01-01

110

Single top quality embryo transfer as a model for prediction of early pregnancy outcome  

Microsoft Academic Search

BACKGROUND: Single embryo transfer (particularly of a top quality embryo) is an excellent model to correlate embryo quality in terms of morphological criteria to early pregnancy. We investigated whether this model could provide us with more information on what happens after implantation in the first trimester of pregnancy. METHODS: The outcome of 370 consecutive single top quality embryo transfers in

D. De Neubourg; J. Gerris; K. Mangelschots; E. Van Royen; M. Vercruyssen; M. Elseviers

2004-01-01

111

A method for preparation of chromosomes from bovine zygotes and blastocysts  

Microsoft Academic Search

A simple technique for making chromosome preparations from zygotes and early blastocysts is described. The morphological features of blastocysts and total number of cells greatly influence the quality of the preparation.

W. A. King; T. Linares; I. Gustavsson; A. Bane

1979-01-01

112

Enhanced accuracy of single-molecule diffusion measurements with a photocleavable energy-transfer dyad.  

PubMed

A photocleavable energy-transfer dyad was synthesized, characterized, and applied to single-molecule fluorescence microscopy. After photocleavage, a combination of independent two-color single-molecule tracking and analysis of single-molecule energy-transfer efficiencies allows the determination of the temporal evolution of the relative distances between both fragments from the nm to the ?m scale. This gives access to a broad range of diffusion coefficients. PMID:24222580

Dill, Maren; Baier, Moritz C; Mecking, Stefan; Wöll, Dominik

2013-11-18

113

Piglets born from centrifuged and vitrified early and peri-hatching blastocysts  

Microsoft Academic Search

Cryopreservation of zona-intact porcine embryos has been relatively unsuccessful to date, although some success has been obtained with lipid reduced morulae and early blastocysts. This study adapted some vitrification protocols used successfully with late blastocysts for use with early zona-intact blastocysts, using actin depolymerization, centrifugation, and open-pulled (OPS) straws.Initially, Day 6 peri-hatching blastocysts were collected, cultured for 40min in 7.5?g\\/ml

L. F. S. Beebe; R. D. A. Cameron; A. W. Blackshaw; A. Higgins; M. B. Nottle

2002-01-01

114

Vitrification of mouse and human blastocysts using a novel cryoloop container-less technique  

Microsoft Academic Search

Objective: To vitrify mouse and human blastocysts with use of the cryoloop procedure and to assess subsequent development.Design: Controlled study of vitrification of mouse and human blastocysts.Setting: Research department of a private assisted reproductive technology unit.Patient(s): Blastocysts that were not suitable to be frozen were donated from patients.Intervention(s): Culture of pronucleate embryos in sequential media to the blastocyst stage.Main Outcome

William B Schoolcraft; David K Gardner; D Phil

1999-01-01

115

Conventional freezing of in vitro-produced and biopsied bovine blastocysts in the presence of a low concentration of glycerol and sucrose.  

PubMed

The purpose of this study was to develop a practical cryopreservation method for in vitro-produced (IVP) and sex-predetermined bovine blastocysts that will be applicable to direct transfer of the post-thaw embryos. Blastocysts were harvested 7 days after IVF and allocated to either an intact or biopsy group. The cryoprotective solution contained 0.7 M glycerol and 0, 0.05 or 0.1 M sucrose. Slow cooling at a rate of -0.5 C/min was terminated at -25, -30, or -35 C, and rapid cooling in liquid nitrogen was followed. After one-step thawing and dilution, the IVP blastocysts were cultured for 3 days to assess their survival. The post-thaw survival rate of intact blastocysts after termination of slow cooling at -30 C in 0.7 M glycerol plus 0.1 M sucrose (96.2%) was significantly higher than that at -25 C in 0.7 M glycerol alone (44.4%). The post-thaw survival rate of biopsied bovine blastocysts after termination of slow cooling at -25 C in 0.7 M glycerol alone (53.8%) tended to be lower than that at -25 C in 0.7 M glycerol plus 0.05 M sucrose (91.3%) or -30 C in 0.7 M glycerol plus 0.1 M sucrose (92.3%). Thus, addition of a small amount of sucrose to 0.7 M glycerol cryoprotective solution shortened the process of slow cooling for both the intact and biopsied bovine embryos. Judged from the survival levels in vitro after thawing and one-step dilution of embryos (>80%), this is an improved method of cryopreservation for subsequent direct transfer of IVP and biopsied bovine blastocysts. PMID:17135713

Tominaga, Keiichiro; Iwaki, Fumiyuki; Hochi, Shinichi

2007-04-01

116

Vitrification of human blastocysts using cryoloops: clinical outcome of 223 cycles  

Microsoft Academic Search

BACKGROUND: The need to cryopreserve human blastocysts is increasing. The successful birth has been reported of a baby from a blastocyst vitrified using the cryoloop technique. The present study expands on this earlier report to confirm the effectiveness of this vitrification procedure. METHODS: In patients undergoing IVF at one of three clinics, supernumerary blastocysts on day 5 or 6 at

T. Mukaida; S. Nakamura; T. Tomiyama; S. Wada; M. Kasai; K. Takahashi

2003-01-01

117

Comprehensive chromosome analysis of blastocysts before implantation using array CGH  

PubMed Central

Background Chromosomal abnormalities are common in embryos produced in vitro and cause implantation failure, miscarriage, and serious medical problems in infants. Because preimplantation genetic screening (PGS) is increasingly being used to detect aneuploidy in embryos with the purpose of improving implantation rates after IVF (in vitro fertilization), we aimed to validate the usefulness of array CGH for the preimplantation genetic screening (PGS) of embryos at the blastocyst stage of development. Results A total of 150 blastocysts were biopsied from couples undergoing IVF and analyzed using array CGH. We found that 54.5% (73/134) of the blastocysts were euploid embryos, whereas 45.5% of the embryos (61/134) had chromosomal abnormalities. Multiple chromosome abnormality was most frequently observed (34.4%), and dual aneuploidy was observed in 26.2% of the embryos. Monosomy (21.3%) appeared more frequently than trisomy (18%). Conclusion Chromosomal microarray analysis provided clinically significant cytogenetic information regarding the frequency and variety of chromosomal abnormalities observed in embryos at the blastocyst stage, suggesting that this is a useful tool for comprehensive aneuploidy screening in IVF.

2013-01-01

118

Single and pair neutron transfers at sub-barrier energies  

NASA Astrophysics Data System (ADS)

Multinucleon transfer cross sections in the 96Zr+40Ca system have been measured, in inverse kinematics, at bombarding energies ranging from the Coulomb barrier to ˜25% below. Targetlike recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental data for one- and two-neutron transfer channels have been compared with semiclassical microscopic calculations. For the two-neutron transfer channels the relevance of the transitions to the ground state and to the 0+ excited states of 42Ca are discussed by employing, for the reaction mechanism, the successive approximation. It is found that the transition to the 0+ state at ˜6 MeV, whose wave function is dominated by the two neutrons in the 2p3/2 shell, is much larger than the ground state one. The comparison with the inclusive data reveals that transitions to states with high multipolarity and non-natural parity are important. This suggests that more complex two-particle correlations have to be incorporated in the treatment of the transfer process.

Corradi, L.; Szilner, S.; Pollarolo, G.; Colò, G.; Mason, P.; Farnea, E.; Fioretto, E.; Gadea, A.; Haas, F.; Jelavi?-Malenica, D.; M?rginean, N.; Michelagnoli, C.; Montagnoli, G.; Montanari, D.; Scarlassara, F.; Soi?, N.; Stefanini, A. M.; Ur, C. A.; Valiente-Dobón, J. J.

2011-09-01

119

PM DEVELOPMENT TASK 5.0 LOCAL BOILING HEAT TRANSFER TESTS. Single Tube Heat Transfer and Pressure Drop Tests  

Microsoft Academic Search

Local boiling heat transfer and pressure drop data were obtained on the ; inside of a single tube test section which was dimensionally identical to a PM-1 ; fuel element. A total of 242 experimental runs were performed, including l32 ; local boiling runs. The test parameters covered were: system pressure from 800 ; to l500 psia; flow rates of

J. J. Jr. Jicha; S. Frank

1961-01-01

120

Single-node orbit analsyis with radiation heat transfer only  

NASA Technical Reports Server (NTRS)

The steady-state temperature of a single node which dissipates energy by radiation only is discussed for a nontime varying thermal environment. Relationships are developed to illustrate how shields can be utilized to represent a louver system. A computer program is presented which can assess periodic temperature characteristics of a single node in a time varying thermal environment having energy dissipation by radiation only. The computer program performs thermal orbital analysis for five combinations of plate, shields, and louvers.

Peoples, J. A.

1977-01-01

121

Single-shot, high repetition rate metallic pattern transfer  

Microsoft Academic Search

A flexible high-speed fabrication of relatively thick (about 1 ?m) and large (about 120×120 ?m) thin film metal pads with a laser-induced forward transfer technique using femtosecond laser pulses (fs-LIFT) will be discussed. Possible applications are thickening of thin film contact pads for wire bonding, the deposition of solder pads or the frequency or electrical resistance tuning of discrete devices.

R. Bähnisch; W. Groß; A. Menschig

2000-01-01

122

Direct measurement of mass transfer around a single bubble by micro-PLIFI  

Microsoft Academic Search

In this paper, an original direct and non-intrusive technique using Planar Laser Induced Florescence with Inhibition (PLIFI) is proposed to quantify the local mass transfer around a single spherical bubble rising in a quiescent liquid. The new set-up tracks the mass transferred in the bubble wake for a plane perpendicular to the bubble trajectory instead of a parallel plane as

J. Francois; N. Dietrich; P. Guiraud; A. Cockx

2011-01-01

123

The transfer matrix: A tool for comparing single stellar population models  

NASA Astrophysics Data System (ADS)

We present the transfer matrix, an analytical tool designed for the study of the model-induced systematic errors in star formation history reconstructions. It is a generalization of the resolution matrix well known in linear inverse problems theory. An application of the transfer matrix is given using the González-Delgado et al. (2005) single stellar population models.

Ocvirk, P.

2005-12-01

124

Serial electrophoretic transfers: A technique for the identification of numerous enzymes from single polyacrylamide gels  

Microsoft Academic Search

We describe an electrophoretic method for the transfer of macromolecules from polyacrylamide slab gels to ion-exchange paper without loss of clarity or resolution. A series of partial transfers provides numerous copies of a single gel separation, and these copies may be assayed independently with enzyme specific stains. This method therefore combines the advantages of polyacrylamide gel electrophoresis for detecting enzyme

Tracy McLellan; John A. M. Ramshaw

1981-01-01

125

Single embryo transfer and multiple pregnancy rate reduction in IVF\\/ICSI: a 5-year appraisal  

Microsoft Academic Search

One of the most problematic issues of assisted reproduction is the high incidence of multiple pregnancies, resulting from the transfer of more than one embryo. Particularly at risk are young women who have good quality embryos. The only strategy to reduce the incidence of multiple pregnancies, including twin pregnancies, after assisted reproduction is single embryo transfer (SET). In 1997, the

P De Sutter; J Van der Elst; T Coetsier; M Dhont

2003-01-01

126

Energy transfer from a single nitrogen-vacancy center in nanodiamond to a graphene monolayer  

NASA Astrophysics Data System (ADS)

In this work, we experimentally demonstrate energy transfer from a single negatively charged nitrogen-vacancy (NV) center in nanodiamond to a graphene monolayer. The mode values of lifetime and intensity of the fluorescence from the single NV center in nanodiamond on monolayer graphene are shorter and weaker than that on bare quartz substrate. The energy transfer efficiency is measured about 40%, consistent with our theoretical estimation.

Liu, Xiaodi; Wang, Guanzhong; Song, Xuerui; Feng, Fupan; Zhu, Wei; Lou, Liren; Wang, Junfeng; Wang, Hong; Bao, Pengfei

2012-12-01

127

Impact of patients' choice for single embryo transfer of a top quality embryo versus double embryo transfer in the first IVF\\/ICSI cycle  

Microsoft Academic Search

BACKGROUND: The aim of this study was to evaluate the impact of transferring a single top quality embryo in the first IVF\\/ICSI cycle of patients 38 years old who chose to have one or two embryos transferred. METHODS: A total of 262 patients participated in the study, and 243 transfers were performed: 156 (64%) patients chose the transfer of a

D. De Neubourg; K. Mangelschots; E. Van Royen; M. Vercruyssen; G. Ryckaert; M. Valkenburg; J. Barudy-Vasquez; J. Gerris

2002-01-01

128

Double and single-electron transfer in H+ +K collisions from 0.3 to 4keV :Separation of direct double transfer and two-step successive single-electron transfer  

Microsoft Academic Search

Double-electron transfer and two-step single-electron transfer in collisions of proton with potassium-metal target are measured in the collision energy from 0.3to4keV by using a charge-inversion mass spectrometry. Two prominent H- ion peaks are observed with different values of the energy loss and show different target density dependences. The peak with larger energy loss is identified as double-electron transfer and the

Shigeo Hayakawa; Kazunori Kadomura; Mineo Kimura; C. M. Dutta

2004-01-01

129

Osmotic behavior of in vitro produced bovine blastocysts in cryoprotectant solutions as a potential predictive test of survival.  

PubMed

The osmotic behavior of bovine blastocysts produced in vitro was filmed during exposure to and dilution of cryoprotectant solutions used for vitrification. The relationship between the changes in the diameter of embryos and their subsequent survival was assessed. Embryos collected on Day 6 and Day 7 postinsemination were exposed to 10% glycerol (GLY) for 5 min, 10% GLY + 20% ethylene glycol (EG) for 5 min, and 25% Gly + 25% EG for 30 s, before dilution in 0.85 M galactose and finally in embryo transfer freezing medium (ETF). Embryos that had a higher probability of survival behaved as perfect osmometers, shrinking, reexpanding, or swelling according to an identical pattern, whereas embryos that deviated from this standard usually did not survive. The initial embryo diameter, duration of shrinkage and expansion in 10% glycerol, duration of reexpansion in ETF, and final embryo diameter were clearly predictive of the ability to hatch after culture in vitro. On a given day postinsemination, larger blastocysts were more likely than smaller blastocysts to survive and hatch after exposure to cryoprotectants with or without vitrification. PMID:11034789

Kaidi, S; Donnay, I; Lambert, P; Dessy, F; Massip, A

2000-09-01

130

Spin-transfer torque on a single magnetic adatom  

NASA Astrophysics Data System (ADS)

We theoretically show how the spin orientation of a single magnetic adatom can be controlled by spin polarized electrons in a scanning tunnelling microscope configuration. The underlying physical mechanism is spin assisted inelastic tunnelling. Experiments with Mn adatoms deposited on a Cu2N surface have been reported for non-polarized currents [1-2]. We show that by changing the direction of the applied current, the orientation of the magnetic adatom can be completely reversed on a time scale that ranges from a few nanoseconds to microseconds, depending on bias and temperature. The changes in the adatom magnetization direction are, in turn, reflected in the tunnelling conductance. Therefore, this effect opens the possibility of writing/reading a single spin without the need of a local magnetic field.[4pt] [1] C.F. Hirjibehedin, C. P. Lutz, A. J. Heinrich, Science 312, 1021 (2006).[0pt] [2] C. Hirjibehedin et al., Science 317, 1199 (2007).

Delgado, Fernando; José Palacios, Juan; Fernández-Rossier, Joaquín

2010-03-01

131

Revealing competitive F?rster-type resonance energy-transfer pathways in single bichromophoric molecules  

PubMed Central

We demonstrate measurements of the efficiency of competing Förster-type energy-transfer pathways in single bichromophoric systems by monitoring simultaneously the fluorescence intensity, fluorescence lifetime, and the number of independent emitters with time. Peryleneimide end-capped fluorene trimers, hexamers, and polymers with interchromophore distances of 3.4, 5.9, and on average 42 nm, respectively, served as bichromophoric systems. Because of different energy-transfer efficiencies, variations in the interchromophore distance enable the switching between homo-energy transfer (energy hopping), singlet-singlet annihilation, and singlet-triplet annihilation. The data suggest that similar energy-transfer pathways have to be considered in the analysis of single-molecule trajectories of donor/acceptor pairs as well as in natural and synthetic multichromophoric systems such as light-harvesting antennas, oligomeric fluorescent proteins, and dendrimers. Here we report selectively visualization of different energy-transfer pathways taking place between identical fluorophores in individual bichromophoric molecules.

Hofkens, Johan; Cotlet, Mircea; Vosch, Tom; Tinnefeld, Philip; Weston, Kenneth D.; Ego, Christophe; Grimsdale, Andrew; Mullen, Klaus; Beljonne, David; Bredas, Jean Luc; Jordens, Sven; Schweitzer, Gerd; Sauer, Markus; De Schryver, Frans

2003-01-01

132

Chemical reaction fouling model for single-phase heat transfer  

SciTech Connect

A fouling model was developed on the premise that the chemical reaction for generation of precursor can take place in the bulk fluid, in the thermalboundary layer, or at the fluid/wall interface, depending upon the interactive effects of flu id dynamics, heat and mass transfer, and the controlling chemical reaction. The analysis was used to examine the experimental data for fouling deposition of polyperoxides produced by autoxidation of indene in kerosene. The effects of fluid and wall temperatures for two flow geometries were analyzed. The results showed that the relative effects of physical parameters on the fouling rate would differ for the three fouling mechanisms; therefore, it is important to identify the controlling mechanism in applying the closed-flow-loop data to industrial conditions.

Panchal, C.B. [Argonne National Lab., IL (United States); Watkinson, A.P. [British Columbia Univ., Vancouver, BC (Canada)

1993-08-01

133

Accuracy evaluation of single-electron shuttle transfer in Si nanowire metal-oxide-semiconductor field-effect transistors  

NASA Astrophysics Data System (ADS)

We report on evaluation of transfer accuracy in a single-electron turnstile using silicon nanowire metal-oxide-semiconductor field-effect transistors at 17 K. Single-electron shuttle transfer and single-shot detection of a single electron are used to detect errors of the transfer. Errors for the transfer through an electrostatically formed island are ascribed to thermal processes. We also observed single-electron transfer mediated by a trap level, which exhibits a wide current plateau and a low error rate.

Yamahata, Gento; Nishiguchi, Katsuhiko; Fujiwara, Akira

2011-05-01

134

The Single Father Family: Recent Trends in Demographic, Economic, and Public Transfer Use Characteristics.  

ERIC Educational Resources Information Center

This conference presentation explores current patterns of public transfer receipt (such as earned income tax credit, public health insurance coverage, food stamps, and public assistance) among single-father families and provides an update on existing census-based research on characteristics of single-father families. Data were obtained from the…

Brown, Brett V.

135

Wdr74 Is Required for Blastocyst Formation in the Mouse  

PubMed Central

Preimplantation is a dynamic developmental period during which a combination of maternal and zygotic factors program the early embryo resulting in lineage specification and implantation. A reverse genetic RNAi screen in mouse embryos identified the WD Repeat Domain 74 gene (Wdr74) as being required for these critical first steps of mammalian development. Knockdown of Wdr74 results in embryos that develop normally until the morula stage but fail to form blastocysts or properly specify the inner cell mass and trophectoderm. In Wdr74-deficient embryos, we find activated Trp53-dependent apoptosis as well as a global reduction of RNA polymerase I, II and III transcripts. In Wdr74-deficient embryos blocking Trp53 function rescues blastocyst formation and lineage differentiation. These results indicate that Wdr74 is required for RNA transcription, processing and/or stability during preimplantation development and is an essential gene in the mouse.

Holston, Olivia; Adams, Danielle; Mager, Jesse

2011-01-01

136

Some factors affecting successful vitrification of mouse blastocysts.  

PubMed

The effects of temperature and exposure time to vitrification solutions on In vitro survival of mouse blastocysts were investigated. Blastocysts were first exposed for 10 min to vitrification Solution 1 (VS1) containing 10% glycerol-20% 1,2 propanediol in phosphate buffered saline (PBS), then to vitrification Solution 2 (VS2) with 25 % glycerol-25% 1,2 propanediol for various periods either at room temperature or at 4 degrees C. At room temperature survival dropped quickly, while at 4 degrees C an increase in survival was observed. It is concluded that the viability of mouse blastocyts after vitrification is dependent on the temperature and duration of equilibration in vitrification solutions. PMID:17087907

Van Der Zwalmen, P; Gaurois, B; Ectors, F J; Touati, K; Massip, A; Ectors, F

1988-12-01

137

Proteomic analysis of bovine blastocoel fluid and blastocyst cells.  

PubMed

Abstract The understanding of the early mammalian development is a prerequisite for the advancement of in vitro fertilization and improvement of derivation and culturing of embryonic stem cells. While, whole genome transcriptomic analysis on bovine blastocysts has identified genes active in early development, little information is available about the protein complement of early embryos. Modern, sensitive proteomic technology (nano HPLC tandem mass spectrometry) allowed us to describe the proteome of the scarce blastocoel fluid and cell material of expanded bovine blastocysts isolated by micromanipulation. From two independent replicates, 23 proteins were identified in the blastocoel fluid while 803 proteins were identified in the remaining cell material. The proteins were grouped into categories according to their gene ontology (GO) terms by which proteins involved in cell differentiation, cell proliferation, development, and reproduction could be derived. Proteins classified in these categories could be candidates for further functional studies to understand pluripotency and early mammalian development. PMID:24568550

Jensen, Pernille Linnert; Grøndahl, Marie Louise; Beck, Hans Christian; Petersen, Jørgen; Stroebech, Lotte; Christensen, Søren Tvorup; Yding Andersen, Claus

2014-06-01

138

Global gene expression analysis identifies molecular pathways distinguishing blastocyst dormancy and activation.  

PubMed

Delayed implantation (embryonic diapause) occurs when the embryo at the blastocyst stage achieves a state of suspended animation. During this period, blastocyst growth is very slow, with minimal or no cell division. Nearly 100 mammals in seven different orders undergo delayed implantation, but the underlying molecular mechanisms that direct this process remain largely unknown. In mice, ovariectomy before preimplantation ovarian estrogen secretion on day 4 of pregnancy initiates blastocyst dormancy, which normally lasts for 1-2 weeks by continued progesterone treatment, although blastocyst survival decreases with time. An estrogen injection rapidly activates blastocysts and initiates their implantation in the progesterone-primed uterus. Using this model, here we show that among approximately 20,000 genes examined, only 229 are differentially expressed between dormant and activated blastocysts. The major functional categories of altered genes include the cell cycle, cell signaling, and energy metabolic pathways, particularly highlighting the importance of heparin-binding epidermal growth factor-like signaling in blastocyst-uterine crosstalk in implantation. The results provide evidence that the two different physiological states of the blastocyst, dormancy and activation, are molecularly distinguishable in a global perspective and underscore the importance of specific molecular pathways in these processes. This study has identified candidate genes that provide a scope for in-depth analysis of their functions and an opportunity for examining their relevance to blastocyst dormancy and activation in numerous other species for which microarray analysis is not available or possible due to very limited availability of blastocysts. PMID:15232000

Hamatani, Toshio; Daikoku, Takiko; Wang, Haibin; Matsumoto, Hiromichi; Carter, Mark G; Ko, Minoru S H; Dey, Sudhansu K

2004-07-13

139

SINGLE-PHASE HEAT TRANSFER ENHANCEMENT TECHNIQUES IN MICROCHANNEL AND MINICHANNEL FLOWS  

Microsoft Academic Search

The single-phase heat transfer enhancement techniques are well established for conventional channels and compact heat exchangers. The major techniques include flow transition, breakup of boundary layer, entrance region, vibration, electric fields, swirl flow, secondary flow and mixers. In the present paper, the applicability of these techniques for single-phase flows in microchannels and minichannels is evaluated. The microchannel and minichannel single-phase

Mark E. Steinke; Satish G. Kandlikar

2004-01-01

140

Double- and single-electron transfer in H{sup +}+K collisions from 0.3 to 4keV: Separation of direct double transfer and two-step successive single-electron transfer  

SciTech Connect

Double-electron transfer and two-step single-electron transfer in collisions of proton with potassium-metal target are measured in the collision energy from 0.3 to 4 keV by using a charge-inversion mass spectrometry. Two prominent H{sup -} ion peaks are observed with different values of the energy loss and show different target density dependences. The peak with larger energy loss is identified as double-electron transfer and the other as two-step successive single-electron transfer from the analysis of the target density dependence. The two-step single-electron transfer is considered to occur as the process accompanying spontaneous Ly-{alpha} emission, followed by negative H{sup -} formation. A theoretical analysis is also carried out, and the single-electron transfer cross section obtained is found to be in excellent agreement with the present measurement, while the present measurement for double-electron transfer is found to be much smaller than those evaluated earlier and the present theory.

Hayakawa, Shigeo; Kadomura, Kazunori; Kimura, Mineo; Dutta, C.M. [College of Integrated Arts and Sciences, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka, 599-8531 (Japan); Graduate School of Sciences, Kyushu University, Hakozaki, Fukuoka 812-8581 (Japan); Department of Physics, Rice University, Houston, Texas 77501 (United States)

2004-08-01

141

Stability of reference genes for normalization of reverse transcription quantitative real-time PCR (RT-qPCR) data in bovine blastocysts produced by IVF, ICSI and SCNT.  

PubMed

Summary Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is a sensitive and accurate tool for quantitative estimation of gene transcription levels in preimplantation embryos. To control for possible experimental variations, gene expression data must be normalized using internal control genes commonly known as reference genes. However, the stability of reference genes can vary depending on the state of development and/or experimental conditions; hence the assessment of their stability is essential before initiating a gene expression analysis. In the present study, we used RT-qPCR to measure the transcript levels of 10 commonly used reference genes and analyzed their expression stability in bovine blastocysts produced by in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT). Using the geNorm program, we found the best combination of genes to normalize gene expression data in bovine embryos at the blastocyst stage produced by IVF (HMBS, SF3A1, and HPRT1), ICSI (H2A, HMBS, and GAPDH), SCNT (ACTB, SF3A1, and SDHA) and/or between blastocysts produced by these methods (GAPDH, HMBS and EEF1A2). We also demonstrated that not only the culture conditions may affect the expression patterns in bovine blastocysts but also the choice of embryo production method may have an important effect. PMID:23731783

Luchsinger, Charlotte; Arias, María Elena; Vargas, Tamara; Paredes, Marcos; Sánchez, Raúl; Felmer, Ricardo

2013-04-26

142

The single electron transfer chemistry of coals. Final report  

SciTech Connect

This research addressed electron donar properties and radical reactions in coal. Solid residues from pyridine Soxhlet extractions of Pocahontas No. 3, Upper Freeport, Pittsburgh No. 8, Illinois No. 6 and Wyodak coals were exposed to 4-vinylpyridine vapors and swelled. All of the 4-vinylpyridine could not be removed under vacuum at 100{degree}C. Diffuse reflectance FTIR revealed the presence of poly-(4-vinylpyridine) in the Illinois No. 6 and Wyodak coals. EPR spectra displayed the loss of inertinite radicals in Upper Freeport, Illinois No. 6 and Wyodak residues after exposure to 4-vinylpyridine. There was little change in the vitrinite radical density or environment. The molecule N,N{prime}-Diphenyl-p-phenylene diamine (DPPD) was exposed to the solid residues from pyridine Soxhlet extractions of the above coals. Diffuse reflectance FTIR failed to detect the imine product from radical reaction with DPPD. EPR spectra displayed the loss of inertinite radicals in Upper Freeport and Wyodak residues. 7,7,8,8-Tetracyanoquinodimethane (TCNQ) and Tetracyanoethylene (TCNE) were deposited into coals in pyridine. FTIR indicated complete conversion of TCNQ to a material with a singly occupied LUMO. In TCNE the LUMO is about 30% occupied. TCNQ and TCNE were deposited into the pyridine extracts and residues of Illinois No. 6 and Pittsburgh No. 8 coals. Only a small amount of the TCNQ and TCNE displayed nitrile shifts in the IR spectrum of a material with an occupied LUMO. It has been concluded that TCNQ must be part of the aromatic stacks in coal and the TCNQ LUMO is part of an extended band.

Larsen, J.W.; Flowers, R.A. II

1994-12-31

143

Early cleavage predicts the viability of human embryos in elective single embryo transfer procedures  

Microsoft Academic Search

BACKGROUND: The reduction of multiple pregnancies by using elective single embryo transfers (eSET) requires critical and careful selection of the embryo for transfer. The current study was undertaken to assess whether early cleavage could be used as a marker of embryo competence in eSET procedures. METHODS: The study included analysis of 178 eSET procedures. All embryos were checked for early

Andres Salumets; Christel Hyden-Granskog; Sirpa Makinen; Anne-Maria Suikkari; Aila Tiitinen; Timo Tuuri

144

Clinical effectiveness of elective single versus double embryo transfer: meta-analysis of individual patient data from randomised trials  

Microsoft Academic Search

Objective To compare the effectiveness of elective single embryo transfer versus double embryo transfer on the outcomes of live birth, multiple live birth, miscarriage, preterm birth, term singleton birth, and low birth weight after fresh embryo transfer, and on the outcomes of cumulative live birth and multiple live birth after fresh and frozen embryo transfers.Design One stage meta-analysis of individual

D. J. McLernon; K. Harrild; C. Bergh; M. J. Davies; D de Neubourg; J. C. M. Dumoulin; J. Gerris; J. A. M. Kremer; H. Martikainen; B. W. Mol; R. J. Norman; A. Thurin-Kjellberg; A. Tiitinen; Montfoort van A. P. A; A M van Peperstraten; E Van Royen; S. Bhattacharya

2010-01-01

145

Single-molecule metal-induced energy transfer (smMIET): resolving nanometer distances at the single-molecule level.  

PubMed

We present a new concept for measuring distance values of single molecules from a surface with nanometer accuracy using the energy transfer from the excited molecule to surface plasmons of a metal film. We measure the fluorescence lifetime of individual dye molecules deposited on a dielectric spacer as a function of a spacer thickness. By using our theoretical model, we convert the lifetime values into the axial distance of individual molecules. Similar to Förster resonance energy transfer (FRET), this allows emitters to be localized with nanometer accuracy, but in contrast to FRET the distance range at which efficient energy transfer takes place is an order of magnitude larger. Our technique can be potentially used as a tool for measuring intramolecular distances of biomolecules and complexes. PMID:24478241

Karedla, Narain; Chizhik, Alexey I; Gregor, Ingo; Chizhik, Anna M; Schulz, Olaf; Enderlein, Jörg

2014-03-17

146

Blastocyst Axis Is Specified Independently of Early Cell Lineage But Aligns with the ZP Shape  

Microsoft Academic Search

The mechanisms controlling the establishment of the embryonic-abembryonic (E-Ab) axis of the mammalian blastocyst are controversial. We used in vitro time-lapse imaging and in vivo lineage labeling to provide evidence that the E-Ab axis of the mouse blastocyst is generated independently of early cell lineage. Rather, both the boundary between two-cell blastomeres and the E-Ab axis of the blastocyst align

Yoko Kurotaki; Kohei Hatta; Kazuki Nakao; Yo-ichi Nabeshima; Toshihiko Fujimori

2007-01-01

147

Activation of peroxisome proliferators-activated receptor ? (PPAR?) promotes blastocyst hatching in mice.  

PubMed

Prostaglandins participate in a variety of female reproductive processes, including ovulation, fertilization, embryo implantation and parturition. In particular, maternal prostacyclin (PGI(2)) is critical for embryo implantation and the action of PGI(2) is not mediated via its G-protein-coupled membrane receptor, IP, but its nuclear receptor, peroxisome-proliferator-activated receptor ? (PPAR?). Recently, several studies have shown that PGI(2) enhances blastocyst development and/or hatching rate in vitro, and subsequently implantation and live birth rates in mice. However, the mechanism by which PGI(2) improves preimplantation embryo development in vitro remains unclear. Using molecular, pharmacologic and genetic approaches, we show that PGI(2)-induced PPAR? activation accelerates blastocyst hatching in mice. mRNAs for PPAR?, retinoid X receptor (heterodimeric partners of PPAR?) and PGI(2) synthase (PGIS) are temporally induced after zygotic gene activation, and their expression reaches maximum levels at the blastocyst stage, suggesting that functional complex of PPAR? can be formed in the blastocyst. Carbaprostacyclin (a stable analogue of PGI(2)) and GW501516 (a PPAR? selective agonist) significantly accelerated blastocyst hatching but did not increase total cell number of cultured blastocysts. Whereas U51605 (a PGIS inhibitor) interfered with blastocyst hatching, GW501516 restored U51605-induced retarded hatching. In contrast to the improvement of blastocyst hatching by PPAR? agonists, PPAR antagonists significantly inhibited blastocyst hatching. Furthermore, deletion of PPAR? at early stages of preimplantation mouse embryos caused delay of blastocyst hatching, but did not impair blastocyst development. Taken together, PGI(2)-induced PPAR? activation accelerates blastocyst hatching in mice. PMID:21511721

Kang, Hee Jung; Hwang, Soo Jin; Yoon, Jung Ah; Jun, Jin Hyun; Lim, Hyunjung Jade; Yoon, Tae Ki; Song, Haengseok

2011-10-01

148

Electronic energy transfer in highly aligned MEH-PPV single chains.  

PubMed

This paper describes the simultaneous measurement of excitation and emission anisotropy to visualize energy transfer in single chains of the prototypical conjugated polymer MEH-PPV, for samples with >70% of the single chains organized into extended, rod-like conformations. The uniformity and high degree of order of the single molecules in these experiments has allowed direct comparison of our experimental data to energy-transfer simulations in model polymer chains. Increases in average anisotropy from 0.62 to 0.74 from excitation to emission and average changes of <15° to the in-plane dipole principal orientation axis confirmed that energy was transferred to a relatively small number of sites in these highly ordered chains. This organization persisted even at large molecular weights (M(n) = 850 kDa). Electronic energy transfer in highly anisotropic model chains was simulated using an incoherent Fo?rster-type mechanism to generate modulation depth histograms in good agreement with the observed data, as well as ensemble emission energies consistent with previously reported results. In these ordered model chains, excitons migrated an average of 6 nm before emission. This distance, far larger than the radius for single-step FRET, implies that energy transfer in MEH-PPV is a multistep funneling process. PMID:21812493

Traub, Matthew C; Lakhwani, Girish; Bolinger, Joshua C; Vanden Bout, David; Barbara, Paul F

2011-08-25

149

Environmental effects on photoinduced electron transfer and fluorescence blinking of single semiconducting nanocrystals in various matrices  

NASA Astrophysics Data System (ADS)

In this report we explore how the surrounding environments around a single semiconducting nancrystal affect the photoinduced electron transfer, charge trapping fluorescence lifetime and fluorescence blinking. Using the time-correlated single photon counting techniques combined with confocal microscopy, we investigated photoluminescence of single CdSe/ZnS quantum dots embedded in agarose gel and on conductive substrates as examples. Understanding of the underlying mechanisms would allow us to better control of the photoluminescence properties of nanoparticles and to improve their performance in biophotonics and optoelectronics applications such as fluorescence markers, single-photon sources, photovoltaics and quantum dot lasers.

Ko, H. C.; Yuan, C. T.; Yu, Ping; Huang, Jane; Tang, Jau

2010-08-01

150

Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene  

NASA Astrophysics Data System (ADS)

We examine the time-resolved resonance energy transfer of excitons from single n-butyl amine-bound, chloride-terminated nanocrystals to two-dimensional graphene through time-correlated single photon counting. The radiative biexponential lifetime kinetics and blinking statistics of the individual surface-modified nanocrystal elucidate the non-radiative decay channels. Blinking modification as well as a 4× reduction in spontaneous emission were observed with the short chloride and n-butylamine ligands, probing the energy transfer pathways for the development of graphene-nanocrystal nanophotonic devices.

Ajayi, O. A.; Anderson, N. C.; Cotlet, M.; Petrone, N.; Gu, T.; Wolcott, A.; Gesuele, F.; Hone, J.; Owen, J. S.; Wong, C. W.

2014-04-01

151

77 FR 49837 - Transfer of Outbound Single-Piece First-Class Mail International Packages and Rolls to...  

Federal Register 2010, 2011, 2012, 2013

...of Outbound Single-Piece First-Class Mail International Packages and Rolls to Competitive...transfer Outbound Single-Piece First-Class Mail International Packages (Small Packets...transfer Outbound Single-Piece First-Class Mail Packages (Small Packets) and Rolls...

2012-08-17

152

Double and single-electron transfer in H{sup +}+K collisions from 0.3 to 4keV: Separation of direct double transfer and two-step successive single-electron transfer  

Microsoft Academic Search

Double-electron transfer and two-step single-electron transfer in collisions of proton with potassium-metal target are measured in the collision energy from 0.3 to 4 keV by using a charge-inversion mass spectrometry. Two prominent H⁻ ion peaks are observed with different values of the energy loss and show different target density dependences. The peak with larger energy loss is identified as double-electron

Shigeo Hayakawa; Kazunori Kadomura; Mineo Kimura; C. M. Dutta

2004-01-01

153

GATA6 Levels Modulate Primitive Endoderm Cell Fate Choice and Timing in the Mouse Blastocyst.  

PubMed

Cells of the inner cell mass (ICM) of the mouse blastocyst differentiate into the pluripotent epiblast or the primitive endoderm (PrE), marked by the transcription factors NANOG and GATA6, respectively. To investigate the mechanistic regulation of this process, we applied an unbiased, quantitative, single-cell-resolution image analysis pipeline to analyze embryos lacking or exhibiting reduced levels of GATA6. We find that Gata6 mutants exhibit a complete absence of PrE and demonstrate that GATA6 levels regulate the timing and speed of lineage commitment within the ICM. Furthermore, we show that GATA6 is necessary for PrE specification by FGF signaling and propose a model where interactions between NANOG, GATA6, and the FGF/ERK pathway determine ICM cell fate. This study provides a framework for quantitative analyses of mammalian embryos and establishes GATA6 as a nodal point in the gene regulatory network driving ICM lineage specification. PMID:24835466

Schrode, Nadine; Saiz, Néstor; Di Talia, Stefano; Hadjantonakis, Anna-Katerina

2014-05-27

154

Photovoltaic devices with an active layer from a stamping transfer technique: single layer versus double layer.  

PubMed

In this study, organic photovoltaic devices with single or double-layered active film were prepared from a stamping transfer technique. A P3HT/PCBM single-layered active layer and a ratio-controlled P3HT/PCBM double-layered active can be successfully fabricated with the help of ultraviolet curable polycarbonate films via a stamping transfer technique. The maximum conversion efficiency values 2.85 for a single active layer transferred device and 3.24% for an optimized double active layer transferred device. Even though transferred double layers should have a sharp interface boundary, an intermixed zone with a concentration gradient was generated by the interpenetration of a donor-rich layer and an acceptor-rich layer in a thermal annealing process. The generation of the intermixed zone is confirmed by Auger electron spectroscopy. The enhanced conversion efficiency levels are attributed to the increased efficiency of the carrier transporting process, which is due to the fact that the concentration gradient is combined with the efficient charge generation from the bulk heterojunction layers. PMID:20302275

Wang, Dong Hwan; Choi, Dae-Geun; Lee, Ki-Joong; Park, O Ok; Park, Jong Hyeok

2010-06-15

155

Effect of the nuclear-donor cell lineage, type, and cell donor on development of somatic cell nuclear transfer embryos in cattle.  

PubMed

Potential applications of somatic cell nuclear transfer to agriculture and medicine are currently constrained by low efficiency and high rates of embryonic, fetal, and neonatal loss. Nuclear transfer efficiency in cattle was compared between three donor-cell treatments from a single animal, between four donor-cell treatments in sequential stages of differentiation from a single cell lineage and genotype, and between the same cell type in two donors. Cumulus and granulosa donor cells resulted in a greater proportion of viable day-7 embryos than ear-skin cells; pregnancy rate and losses were not different among treatments. The least differentiated cell type in the follicular cell lineage, preantral follicle cells, resulted in fewer cloned blastocysts (11%) than cumulus (30%), granulosa (23%), and luteal (25%) donor cells. Cloned blastocysts that did develop from preantral follicle cells (75%) were more likely to progress through implantation into later stages of pregnancy than cloned blastocysts from cumulus (10%), granulosa (9%), and luteal (11%) donor cells (p < 0.05). Day-7 embryo development from granulosa cells was similar between two donors (19 vs. 24%) and proved to be a poor indicator of further development as day-30 pregnancy rates varied threefold between donors (48 vs. 15%, p < 0.05). Results reported here emphasize the crucial role of the nuclear donor cell in the outcome of the nuclear-transfer process. PMID:16390260

Batchelder, Cynthia A; Hoffert, Kara A; Bertolini, Marcelo; Moyer, Alice L; Mason, Jeffery B; Petkov, Stoyan G; Famula, Thomas R; Anderson, Gary B

2005-01-01

156

Near-Resonant Vibration Implies Vibration Energy Transfer under Single-Collision Conditions.  

National Technical Information Service (NTIS)

Energy transfer in single collisions of propynal (HC triple bond C-CHO) subsequent to ir multiphonon absorption (CO sub 2 laser) was studied. SiF sub 4 , CH sub 3 F, CCl sub 4 , and CH sub 4 were added. (ERA citation 06:019033)

D. M. Breener

1981-01-01

157

Solution Casting and Transfer Printing Single-Walled Carbon Nanotube Films  

Microsoft Academic Search

This paper presents methods for solution casting and transfer printing collections of individual single-walled carbon nanotubes (SWNTs) onto a wide range of substrates, including plastic sheets. The deposition involves introduction of a solvent that removes surfactant from a suspension of SWNTs as it is applied to a substrate. The subsequent controlled flocculation (cF) produces films of SWNTs with densities that

Matthew A. Meitl; Yangxin Zhou; Anshu Gaur; Seokwoo Jeon; Monica L. Usrey; Michael S. Strano; John A. Rogers

2004-01-01

158

Early cleavage: an additional predictor of high implantation rate following elective single embryo transfer  

Microsoft Academic Search

The value of early cleavage (EC) assessment is still being debated. The aim of this prospective study was to examine the predictive value of EC assessment performed exactly 26 h after insemination by IVF or intracytoplasmic sperm injection (ICSI) in a programme of elective single embryo transfer (SET) performed at day 2. If day 2 scoring demonstrated several embryos with

C Giorgetti; E Hans; P Terriou; J Salzmann; B Barry; V Chabert-Orsini; JM Chinchole; JP Franquebalme; E Glowaczower; M-C Sitri; M-C Thibault; R Roulier

2007-01-01

159

Comparison of clinical outcomes between fresh embryo transfers and frozen-thawed embryo transfers  

PubMed Central

Background: Advances in embryo culture technology and cryopreservation have led to a shift in in vitro fertilization (IVF) from early fresh or frozen-thawed cleavage embryo transfer to fresh or frozen-thawed blastocyst stage transfer. Objective: To compare the clinical outcomes of fresh embryo transfers and frozen-thawed embryo transfers. Materials and Methods: In this retrospective case control study, patients undergoing IVF cycles from January 2012 to December 2012 were enrolled in Assisted Reproduction of Wuhan Union Hospital were enrolled. A total of 1891 cycle contains 1150 fresh embryo transfers and 741 frozen-thawed embryo transfers were studied. All data were transferred directly to SPSS 18 and analyzed. Results: Clinical pregnancy rates of fresh cleavage-stage embryo transfers compared with fresh blastocyst transfers, frozen-thawed cleavage-stage embryo transfers, post thaw cleavage-stage extended blastocyst culture transfers and frozen-thawed blastocyst transfers were 52.7%, 35.88%, 35.29%, 47.75%, 59.8% in patients under 35 years of ages and 41.24%, 26.92%, 11.32%, 46.15%, 55.8% in patients older than 35 years old, respectively. The multiple pregnancy rates, abortion rates and ectopic pregnancy rates did not differ significantly among the five groups. Conclusion: The clinical pregnancy rates were not different significantly between fresh cleavage-stage embryo transfers and fresh blastocyst transfers. But the clinical pregnancy rate of frozen-thawed blastocyst transfer was the highest among fresh/frozen-thawed embryo transfers.

Shen, Chunjuan; Shu, Defeng; Zhao, Xiaojie; Gao, Ying

2014-01-01

160

Gene expression profiles of vitrified in vitro- and in vivo-derived bovine blastocysts.  

PubMed

Vitrification is becoming a preferred method for pre-implantation embryo cryopreservation. The objective of this study was to determine the differentially expressed genes of in vivo- and in vitro-produced bovine embryos after vitrification. In vitro- (IVF) and in vivo-derived (IVV) bovine blastocysts were identified as follows: in vitro-produced fresh (IVF-F), in vitro-produced vitrified (IVF-V), in vivo-derived fresh (IVV-F), in vivo-derived vitrified (IVV-V). The microarray results showed that 53 genes were differentially regulated between IVF and IVV, and 121 genes were differentially regulated between fresh and vitrified blastocysts (P?blastocysts (P?blastocysts. Significantly up-regulated KEGG pathways included ribosome, oxidative phosphorylation, spliceosome, and oocyte meiosis in the fresh IVF blastocyst samples, while sphingolipid and purine metabolisms were up-regulated in the vitrified IVF blastocyst. The results showed that in vitro bovine blastocyst production protocols used in this study caused no major gene expression differences compared to those of in vivo-produced blastocysts. After vitrification, however, in vitro-produced blastocysts showed major gene expression differences compared to in vivo blastocysts. This study suggests that in vitro-produced embryos are of comparable quality to their in vivo counterparts. Vitrification of in vitro blastocysts, on the other hand, causes significant up-regulation of genes that are involved in stress responses. PMID:22778065

Aksu, Digdem Aktoprakligil; Agca, Cansu; Aksu, Soner; Bagis, Haydar; Akkoc, Tolga; Caputcu, Arzu Tas; Arat, Sezen; Taskin, Ali Cihan; Kizil, Sedat H; Karasahin, Tahir; Akyol, Numan; Satilmis, Muharrem; Sagirkaya, Hakan; Ustuner, Burcu; Nur, Zekeriya; Agca, Yuksel

2012-09-01

161

Single and Multi-Nucleon Transfer Reactions for Nuclear Moment Studies Toward Radioactive-Ion Beams  

SciTech Connect

This study is a part of an experimental program to measure nuclear moments in transfer reactions. It aims to probe for a first time the nuclear -spin orientation in multi-nucleon transfer. Fist experiments were performed to measure the quadrupole moment of an isomeric state in {sup 66}Cu (I{sup p}i 6{sup -}, E{sub x} = 1154 keV, T{sub 1/2} = 595(20) ns) in single nucleon transfer and the population of mus isomers in {sup 66}Cu and {sup 63}Ni in multi-nucleon transfer. The experimentally tested methodology allows broad applications toward more exotic species and feasibility of these reactions to produce species away from stability.

Lozeva, R. L.; Georgiev, G. P.; Audi, G.; Cabaret, S.; Fiori, E.; Gaulard, C.; Hauschilda, K.; Lopez-Martens, A.; Risegari, L. [CSNSM, Universite Paris-Sud 11, CNRS/IN2P3, F-91405 Orsay-Campus (France); Balabanski, D. L. [INRNE, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Blazhev, A.; Jolie, J.; Moschner, K.; Zell, K.-O. [IKP, Universitaet zu Koeln, DE-50937 Cologne (Germany); Daugas, J.-M.; Faul, T.; Morel, P.; Roig, O. [CEA, DAM, DIF, F-91297 Arpajon Cedex (France); Ferraton, M.; Ibrahim, F. [IPN, CNRS/IN2P3, F-91406 Orsay-Campus (France)

2010-04-30

162

Uterine Micro-Environment and Estrogen-Dependent Regulation of Osteopontin Expression in Mouse Blastocyst  

PubMed Central

Embryo implantation is a highly synchronized bioprocess between an activated blastocyst and a receptive uterus. In mice, successful implantation relies on the dynamic interplay of estrogen and progesterone; however, the key mediators downstream of these hormones that act on blastocyst competency and endometrium receptivity acquisition are largely unknown. In this study, we showed that the expression of osteopontin (OPN) in mouse blastocysts is regulated by ovarian estrogen and uterine micro-environment. OPN mRNA is up-regulated in mouse blastocyst on day 4 of pregnancy, which is associated with ovarian estrogen secretion peak. Hormone treatment in vivo demonstrated that OPN expression in a blastocyst is regulated by estrogen through an estrogen receptor (ER). Our results of the delayed and activated implantation model showed that OPN expression is induced after estrogen injection. While estrogen treatment during embryo culture in vitro showed less effect on OPN expression, the tubal ligation model on day 3 of pregnancy confirmed that the regulation of estrogen on OPN expression in blastocyst might, through some specific cytokines, have existed in a uterine micro-environment. Collectively, our study presents that estrogen regulates OPN expression and it may play an important role during embryo implantation by activating blastocyst competence and facilitating the endometrium acceptable for active blastocyst.

Xie, Qing-Zhen; Qi, Qian-Rong; Chen, Ying-Xian; Xu, Wang-Ming; Liu, Qian; Yang, Jing

2013-01-01

163

The Influence of Polyvinylpyrrolidone on Freezing of Bovine IVF Blastocysts Following Biopsy  

Microsoft Academic Search

A study was conducted to develop a better freezing protocol for in vitro developed biopsied bovine blastocysts. Biopsied blastocysts were exposed to 1.8 M ethylene glycol (EG) + 0.05 M trehalose (T) and different concentration (5, 10, and 20%) of polyvinylpyrrolidone (PVP). Exposure to the solutions alone did not affect their in vitro development (Experiment 1). Experiments 2, 3, and

T. Suzuki; S. Saha; C. Sumantri; M. Takagi; A. Boediono

1995-01-01

164

Estrogen-Dependent Uterine Secretion of Osteopontin Activates Blastocyst Adhesion Competence  

PubMed Central

Embryo implantation is a highly orchestrated process that involves blastocyst-uterine interactions. This process is confined to a defined interval during gestation referred to as the “window of embryo implantation receptivity”. In mice this receptive period is controlled by ovarian estrogen and involves a coordination of blastocyst adhesion competence and uterine receptivity. Mechanisms coordinating the acquisition of blastocyst adhesion competence and uterine receptivity are largely unknown. Here, we show that ovarian estrogen indirectly regulates blastocyst adhesion competence. Acquisition of blastocyst adhesion competence was attributed to integrin activation (e.g. formation of adhesion complexes) rather than de novo integrin synthesis. Osteopontin (OPN) was identified as an estrogen-dependent uterine endometrial gland secretory factor responsible for activating blastocyst adhesion competence. Increased adhesion complex assembly in OPN-treated blastocysts was mediated through focal adhesion kinase (FAK)- and phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathways. These findings define for the first time specific regulatory components of an estrogen-dependent pathway coordinating blastocyst adhesion competence and uterine receptivity.

Egashira, Mahiro; Bai, Rulan; Nomura, Nana; Nomura, Shintaro; Hirota, Yasushi; Sakurai, Toshihiro; Imakawa, Kazuhiko

2012-01-01

165

Differentiation prevents assessment of neural stem cell pluripotency after blastocyst injection.  

PubMed

Earlier studies reported that neural stem (NS) cells injected into blastocysts appeared to be pluripotent, differentiating into cells of all three germ layers. In this study, we followed in vitro green fluorescent protein (GFP)-labeled NS and embryonic stem (ES) cells injected into blastocysts. Forty-eight hours after injection, significantly fewer blastocysts contained GFP-NS cells than GFP-ES cells. By 96 hours, very few GFP-NS cells remained in blastocysts compared with ES cells. Moreover, 48 hours after injection, GFP-NS cells in blastocysts extended long cellular processes, ceased expressing the NS cell marker nestin, and instead expressed the astrocytic marker glial fibrillary acidic protein. GFP-ES cells in blastocysts remained morphologically undifferentiated, continuing to express the pluripotent marker stage-specific embryonic antigen-1. Selecting cells from the NS cell population that preferentially formed neurospheres for injection into blastocysts resulted in identical results. Consistent with this in vitro behavior, none of almost 80 mice resulting from NS cell-injected blastocysts replaced into recipient mothers were chimeric. These results strongly support the idea that NS cells cannot participate in chimera formation because of their rapid differentiation into glia-like cells. Thus, these results raise doubts concerning the pluripotency properties of NS cells. PMID:15277705

Gréco, Béatrice; Low, Hoi Pang; Johnson, Eric C; Salmonsen, Rebecca A; Gallant, Judith; Jones, Stephen N; Ross, Alonzo H; Recht, Lawrence D

2004-01-01

166

Submicroscopic localization of glycogen in mouse blastocysts developed in vivo and in blastocysts developed in vitro from two-cell embryos.  

PubMed

Ultrahistochemical method according to Thiéry (1967) was used to determine the occurrence and localization of glycogen in blastocysts developed in vivo and in blastocysts developed from 2-cell embryos of the mouse for 62 to 64 h in in vitro culture. The presence of glycogen was found in blastocysts of both experimental groups. Glycogen had a monoparticulate character, i.e. the form of beta-granules, localized above all in the ground cytoplasm of cells. Their size varied from 10 to 30 nm. In the blastocysts developed in the physiological uterine environment the glycogen content was relatively low, trophoblasts cells containing regularly a higher amount of glycogen particles than embryoblast cells. In the blastocysts developed in the culture medium in the presence of currently used energy sources the distribution and content of glycogen were clearly graded according to the cell types. Compared with the in vivo-blastocysts, an abnormally high amount of glycogen was observed in the cytoplasm of trophoblast cells, a medium amount in the prospective endoderm cells and the minimum amount in the prospective ectoderm cells. The authors are of the opinion that differences in the accumulation of glycogen and its occurrence in the individual cells are in connection with their position in the blastocyst and with their relation to the surrounding microenvironment. It can be judged from the findings of glycogen deposits inside autophagic vacuoles and multivesicular bodies as well as inside extracellular located sacs that simultaneously with glycogen accumulation there also proceeds its partial degradation in lysosomal structures of blastocyst cells. PMID:2514548

Stastná, J; Cech, S

1989-01-01

167

Energy Transfer in Reconstituted Peridinin-Chlorophyll-Protein Complexes: Ensemble and Single-Molecule Spectroscopy Studies  

PubMed Central

We combine ensemble and single-molecule spectroscopy to gain insight into the energy transfer between chlorophylls (Chls) in peridinin-chlorophyll-protein (PCP) complexes reconstituted with Chl a, Chl b, as well as both Chl a and Chl b. The main focus is the heterochlorophyllous system (Chl a/b-N-PCP), and reference information essential to interpret experimental observations is obtained from homochlorophyllous complexes. Energy transfer between Chls in Chl a/b-N-PCP takes place from Chl b to Chl a and also from Chl a to Chl b with comparable Förster energy transfer rates of 0.0324 and 0.0215 ps?1, respectively. Monte Carlo simulations yield the ratio of 39:61 for the excitation distribution between Chl a and Chl b, which is larger than the equilibrium distribution of 34:66. An average Chl a/Chl b fluorescence intensity ratio of 66:34 is measured, however, for single Chl a/b-N-PCP complexes excited into the peridinin (Per) absorption. This difference is attributed to almost three times more efficient energy transfer from Per to Chl a than to Chl b. The results indicate also that due to bilateral energy transfer, the Chl system equilibrates only partially during the excited state lifetimes.

Mackowski, Sebastian; Wormke, Stephan; Brotosudarmo, Tatas H. P.; Jung, Christophe; Hiller, Roger G.; Scheer, Hugo; Brauchle, Christoph

2007-01-01

168

Efficient production of sex-identified and cryosurvived bovine in-vitro produced blastocysts.  

PubMed

To establish a protocol for production of bovine in-vitro produced (IVP) blastocysts that were sex-identified and cryopreserved, we examined the sexing efficiency and accuracy of Day-3 and Day-4 embryos by polymerase chain reaction (PCR), the development of the biopsied embryos into Day-7 blastocysts and the freezability of these blastocysts by vitrification in gel-loading tips. One or two blastomeres were isolated from IVP embryos at either the 8-cell or 16-cell stage (Days 3 and 4, respectively) by a pressing-out method, and were then subjected to primer extension preamplification (PEP)-PCR. The successful sex-identification rate of biopsied samples amplified, purified and analyzed for sex by a second PCR (88.9%) was higher than that of those amplified and analyzed without purification (32.0%). Developmental rates into Day-7 blastocysts of biopsied embryos (Day-3, 65.5%; Day-4, 70.8%) were similar to those of non-biopsied control embryos (Day-3, 74.5%; Day-4, 65.1%). Total cell numbers and the inner cell mass (ICM) ratio of blastocysts derived from biopsied embryos were also comparable with those of control embryos. Blastocysts were vitrified-warmed in the presence of 20% DMSO, 20% ethylene glycol and 0.6M sucrose using gel-loading tips as containers. The proportions of biopsied blastocysts that were hatched or hatching rates after warming were high, regardless of the biopsy time (Day-3, 94.1%; Day-4, 91.9%), similar to the rates for control blastocysts (Day-3, 97.5%; Day-4, 96.9%). In conclusion, a protocol that allows sexing of Day-3 and Day-4 bovine embryos without compromising either the developmental ability to the blastocyst stage or freezability of Day-7 blastocysts was developed. PMID:15037005

Tominaga, Keiichiro; Hamada, Yukako

2004-04-15

169

Genetic and environmental determinants of interferon-tau secretion by in vivo- and in vitro-derived bovine blastocysts.  

PubMed

Several experiments were conducted to assess the effects of genotype and various culture media on interferon-tau secretion by in vitro-derived bovine blastocysts and to compare these values with interferon released by blastocysts flushed from superovulated cows. In experiment 1, oocytes were inseminated with semen from three different bulls. While paternal genotype had no effect on cleavage rate, the size or hatching ability of blastocysts, it was a significant determinant of the embryo's ability to develop to the blastocyst stage and of subsequent interferon-tau secretion. In the second experiment, embryos were cultured in synthetic oviductal fluid containing either polyvinyl alcohol, bovine serum albumin or fetal bovine serum. While there was no effect of supplement on the percentage of embryos developing to the blastocyst stage, blastocysts which formed in medium with polyvinyl alcohol had significantly fewer cells, were older at blastocyst formation and produced significantly more interferon-tau. In the third experiment, embryos were cultured to the blastocyst stage in either TCM199 alone or in co-culture with buffalo rat liver, bovine oviductal or bovine uterine epithelial cells. Culture with oviductal or buffalo rat liver cells increased blastocyst cell number, although secretion of interferon-tau was not affected. In the final experiment, bovine blastocysts were flushed from superovulated cows on Day 7 following insemination. Overall, secretion of interferon-tau by in vivo-produced blastocysts did not differ from that of age-matched blastocysts produced in vitro. PMID:11343838

Kubisch, H M; Larson, M A; Ealy, A D; Murphy, C N; Roberts, R M

2001-04-30

170

Single electron transfer between selectfluor and chloride: A mass spectrometric and theoretical study  

NASA Astrophysics Data System (ADS)

The reaction between 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-tetrafluoroborate (selectfluor) and chloride has been studied experimentally and modeled computationally at the ab initio levels. Based on the interception experiments by electrospray ionization-mass spectrometry (ESI-MS), it is found that only 5,5-dimethyl-l-pyrroline N-oxide (DMPO) succeeds in trapping the chlorine free radical. This result indicates that the single electron transfer (SET) is likely to occur between selectfluor and chloride. According to the Marcus' theory, the activation and reaction free energies for this electron transfer have been calculated. The theoretical study shows that the electron transfer reaction is both thermodynamically and kinetically beneficial, which is consistent with the experiment.

Zhang, Xiang

2013-10-01

171

Optical-frequency transfer over a single-span 1840 km fiber link.  

PubMed

To compare the increasing number of optical frequency standards, highly stable optical signals have to be transferred over continental distances. We demonstrate optical-frequency transfer over a 1840-km underground optical fiber link using a single-span stabilization. The low inherent noise introduced by the fiber allows us to reach short term instabilities expressed as the modified Allan deviation of 2×10(-15) for a gate time ? of 1 s reaching 4×10(-19) in just 100 s. We find no systematic offset between the sent and transferred frequencies within the statistical uncertainty of about 3×10(-19). The spectral noise distribution of our fiber link at low Fourier frequencies leads to a ?(-2) slope in the modified Allan deviation, which is also derived theoretically. PMID:24074067

Droste, S; Ozimek, F; Udem, Th; Predehl, K; Hänsch, T W; Schnatz, H; Grosche, G; Holzwarth, R

2013-09-13

172

Light-induced heat and mass transfer in a single-component gas in a capillary  

SciTech Connect

A theoretical analysis is presented of light-induced heat and mass transfer in a single-component gas in a capillary tube at arbitrary Knudsen numbers. Surface and collisional mechanisms of transfer are analyzed, due to differences in accommodation coefficient and collision cross section between excited-and ground-state particles, respectively. Analytical expressions for kinetic coefficients characterizing the gas drift and heat transfer in a capillary tube are obtained in the limits of low and high Knudsen numbers. Numerical computations are performed for intermediate Knudsen numbers. Both drift and heat fluxes are determined as functions of the light beam frequency. In the case of an inhomogeneously broadened absorption line, the light-induced fluxes are found to depend not only on the sign, but also on the amount, of light beam detuning from the absorption line center frequency.

Chermyaninov, I. V., E-mail: vladimir.chernyak@usu.ru; Chernyak, V. G.; Vilisova, E. A. [Ural State University (Russian Federation)

2007-10-15

173

Multi-Color Single Molecule Fluorescence Resonance Energy Transfer (smFret)  

NASA Astrophysics Data System (ADS)

The assembly of multi-protein complexes is a vital part of intracellular biology. High resolution methods for characterizing such multi-protein complexes are required to understand functions of these complexes at the mechanistic level. Single molecule Fluorescence Resonance Energy Transfer is a promising method for both characterizing protein conformations and co-localizing different members of such multi-protein complexes. We present our progress towards developing an instrument for three and four color FRET studies at the single molecule level. This method will be useful for characterizing multi-protien complexes.

Anderson, Trevor; Weninger, Keith

2008-10-01

174

Single Neutron Transfer Experiments Close to the r-Process Path  

SciTech Connect

The first measurements using the (d, p) transfer reaction to study single- particle states in nuclei on the expected r-process path have been made at the Holifield Radioactive Ion Beam Facility. The shell closure at N = 50 has been crossed using the 82Ge(d, p) and 84Se(d, p) reactions. The prop- erties of the lowest-lying states have been determined. Furthermore, the 132Sn(d, p) reaction has been used for the first time to populate single- particle states in 133Sn.

Grzywacz-Jones, Kate L [ORNL; Adekola, Aderemi S [ORNL; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, Kyung Yuk [ORNL; Chipps, K. [Colorado School of Mines, Golden; Cizewski, Jolie [ORNL; Dean, David Jarvis [ORNL; Erikson, Luke [Colorado School of Mines, Golden; Fitzgerald, R. P. [University of North Carolina, Chapel Hill; Gaddis, A. L. [Furman University; Greife, U. [Colorado School of Mines, Golden; Harlin, Christopher W [ORNL; Hatarik, Robert [Rutgers University; Howard, Joshua A [ORNL; Johnson, Micah [ORNL; Kozub, R. L. [Tennessee Technological University; Liang, J Felix [ORNL; Livesay, Jake [ORNL; Ma, Zhanwen [ORNL; Moazen, Brian [University of Tennessee, Knoxville (UTK); O'Malley, Patrick [Rutgers University; Nesaraja, Caroline D [ORNL; Pain, S. D. [Rutgers University; Patterson, N. P. [University of Surrey, UK; Paulauskas, Stanley V [ORNL; Shapira, Dan [ORNL; ShrinerJr., J. F. [Tennessee Technological University; Sissom, D. J. [Tennessee Technological University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK; Thomas, J. S. [Rutgers University

2007-01-01

175

Electron transfer-based single molecule fluorescence as a probe for nano-environment dynamics.  

PubMed

Electron transfer (ET) is one of the most important elementary processes that takes place in fundamental aspects of biology, chemistry, and physics. In this review, we discuss recent research on single molecule probes based on ET. We review some applications, including the dynamics of glass-forming systems, surface binding events, interfacial ET on semiconductors, and the external field-induced dynamics of polymers. All these examples show that the ET-induced changes of fluorescence trajectory and lifetime of single molecules can be used to sensitively probe the surrounding nano-environments. PMID:24496314

Chen, Ruiyun; Wu, Ruixiang; Zhang, Guofeng; Gao, Yan; Xiao, Liantuan; Jia, Suotang

2014-01-01

176

LOAD TRANSFER AND MECHANICAL PROPERTIES OF CHEMICALLY DERIVED SINGLE LAYER GRAPHENE REINFORCEMENTS IN POLYMER COMPOSITES  

PubMed Central

We report load transfer and mechanical properties of chemically derived single layer graphene (SLG) as reinforcements in poly (dimethyl) siloxane (PDMS) composites. Mixing single layer graphene in polymers resulted in the marked decrease of the G’ or 2D band intensity due to doping and functionalization. A Raman G mode shift of 11.2 cm?1/% strain in compression and 4.2 cm?1/% strain in tension is reported. An increase in elastic modulus of PDMS by ~42%, toughness by ~39%, damping capability by ~673%, and strain energy density of ~43% by the addition of 1 wt. % SLG in PDMS is reported.

Xu, Peng; Loomis, James; Panchapakesan, Balaji

2013-01-01

177

Doping single-walled carbon nanotubes through molecular charge-transfer: a theoretical study  

Microsoft Academic Search

We study the effect of the molecular charge transfer on the electronic structure of metallic (5,5) and semiconducting (8,0) single-walled carbon nanotubes (SWNTs) induced by surface adsorption of various organic donor-acceptor molecules of different affinities using ab initio density functional theory. Our results, obtained from first-principles spin-polarized calculations show that the adsorption of molecules with different affinities reflects the difference

Arun K. Manna; Swapan K. Pati

2010-01-01

178

Electron irradiation of single crystal thorium dioxide and electron transfer reactions  

Microsoft Academic Search

This first study of electron irradiation (3 MeV) of single crystals of thoria has revealed that the crystals turn blue, as seen with neutron irradiation, but the absorption profiles in the 12?000–17?260 cm?1 (1.49–2.14 eV) region were similar but not identical. Calculations showed that the electrons transferred energy sufficient to displace lattice oxygen atoms, but not thorium atoms. The crystals

Trevor R Griffiths; James Dixon

2000-01-01

179

Method of calculating gas dynamics and heat transfer in single stage refrigeration units  

NASA Technical Reports Server (NTRS)

A generalized mathematical model of gas-dynamic and heat transfer processes in single-stage regenerative installations operating in Stirling, MacMahon, Gifford-MacMahon, and pulsating tube cycles is proposed. A numerical method os solving initial equations on a digital computer is given. This makes it possible to calculate the change in the thermodynamic parameters in the working cycle in different machine components, as well as the dependence of cold productivity on the temperature level in the steady regime.

Zhitomirskiy, I. S.; Popolskiy, A. B.

1974-01-01

180

Single Molecule Fluorescence Resonance Energy Transfer (smFRET) in Live Cells  

NASA Astrophysics Data System (ADS)

This research reports progress towards single molecule fluorescence resonance energy transfer (smFRET) in the cytoplasmic environment of live cells. Recombinantly expressed, externally dye-labeled SNARE proteins were microinjected into cultured cells, tracked and imaged to observe real-time conformational dynamics. We discuss the many obstacles lowering signal:noise in vivo (cellular and coverslip autofluorescence, dye photobleaching) and our methods for overcoming these obstacles. Initial findings and the implications for this technique will also be discussed.

Sakon, John; Weninger, Keith

2008-10-01

181

Expression of HSG is essential for mouse blastocyst formation  

SciTech Connect

It has been shown recently that hyperplasia suppressor gene (HSG) is a powerful regulator for cell proliferation and has a critical role in mitochondrial fusion in many cells. However, little is known about its expression, localization, and function during oocyte maturation and early embryogenesis. In this study, with indirect immunofluorescent staining and Western blotting, we found that HSG was expressed in mouse oocytes and preimplantation embryos which primarily exhibited a submembrane distribution pattern in the cytoplasm. Moreover, HSG mainly associated with {beta}-tubulin during oocyte maturation and early embryonic development. When mouse zygotes were injected with HSG antisense plasmid and cultured in vitro, their capacity to form blastocysts was severely impaired. Our results indicate that HSG plays an essential role in mouse preimplantation development.

Jiang Guangjian [Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080 (China); Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017 (China); Department of Biochemistry and Molecular Biology, North China Coal Medical College, Tangshan 063000 (China); Pan Lei [Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100080 (China); Huang Xiuying [Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080 (China); Han Mei [Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017 (China); Wen Jinkun [Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017 (China)]. E-mail: wjk@hebmu.edu.cn; Sun Fangzhen [Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080 (China)]. E-mail: fzsun@genetics.ac.cn

2005-09-23

182

Modulation of murine blastocyst hatching in vitro by glutamine and tryptophan.  

PubMed

Enrichment of culture media with amino acids improves embryo development. However, little is known about the specific action of each amino acid during embryogenesis. The present study was undertaken to examine the effect of L-glutamine (Gln) and tryptophan (Trp) on mouse embryo hatching, expansion and viability in vitro. Blastocysts were collected from 6- to 8-week-old female BALB/c mice (N = 30) and cultured in M2 medium containing either 0.125, 0.25 or 0.5 mM Trp, 1 mM Gln, or M2 alone. Gln significantly increased (100%; P < 0.05) blastocyst hatching at 24 h compared to M2 alone or Trp; moreover, Trp inhibited blastocyst hatching when compared to M2 alone (P < 0.05) at 72 h. In contrast, the percentage of embryos reaching the state of expanded blastocyst at 48 h was significantly higher in medium with 1 mM Gln (66.6%; P < 0.05) or with 0.125 mM Trp (61.1%; P < 0.05). Unexpectedly, Trp increased the percentage of degenerated blastocysts after 48 h (67.7%; P < 0.05), while Gln preserved blastocyst viability. These results suggest that Gln may enhance blastocyst hatching, expansion and viability in vitro. PMID:21710103

Castro, W; Bueno Sánchez, J C; Piedrahita-Ochoa, C; Cadavid J, A P

2011-08-01

183

What next for preimplantation genetic screening (PGS)? Experience with blastocyst biopsy and testing for aneuploidy.  

PubMed

Blastocysts more commonly have a normal karyotype than cleavage-stage embryos do. Moreover, blastocysts have also made a metabolic transition from catabolism and recycling of the oocyte's reserves and resources, processes that fuel the first 3 days of cleavage. Although not all blastocysts are karyotypically equal, it is still to be determined to what extent a mosaic karyotype might be a normal feature among embryos, both at the cleavage stage and the blastocyst stage--and when looking for karyotypic abnormalities by embryo biopsy might help the chance of implantation rather than harm it. It is also still impractical to look at all the chromosomes that can, through their aneuploidy, stand in the way of successful embryonic and fetal development. We report a randomized clinical trial of blastocyst biopsy followed by preimplantation genetic screening (PGS) for aneuploidy using 5-colour FISH. The trial was suspended and then terminated early when we were unable to show an advantage for PGS. If we are correct in assuming that mitotic non-disjunction is common by the stage of the blastocyst (and that it is much less ominous than meiotic non-disjunction), then further studies of effective PGS of blastocysts for aneuploidy require methods of analysis that cover all the chromosomes and can differentiate the triallelic and monoallelic states of meiotically derived aneuploidies from the biallelic state of mitotic aneuploidies. PMID:18539624

Jansen, Robert P S; Bowman, Mark C; de Boer, Kylie A; Leigh, Don A; Lieberman, Devora B; McArthur, Steven J

2008-07-01

184

Trichostatin A improves histone acetylation in bovine somatic cell nuclear transfer early embryos.  

PubMed

Epigenetic aberrancies likely preclude correct and complete nuclear reprogramming following somatic cell nuclear transfer (SCNT), and may underlie the observed reduced viability of cloned embryos. In the present study, we tested the effects of the histone deacetylase inhibitor (HDACi), trichostatin A (TSA), on development and histone acetylation of cloned bovine preimplantation embryos. Our results indicated that treating activated reconstructed SCNT embryos with 50 nM TSA for 13 h produced eight-cell embryos with levels of acetylation of histone H4 at lysine 5 (AcH4K5) similar to fertilized counterparts and significantly greater than in control NT embryos (p < 0.005). Further, TSA treatment resulted in SCNT embryos with preimplantation developmental potential similar to fertilized counterparts, as no difference was observed in cleavage and blastocyst rates or in blastocyst total cell number (p > 0.05). Measurement of eight selected developmentally important genes in single blastocysts showed a similar expression profile among the three treatment groups, with the exception of Nanog, Cdx2, and DNMT3b, whose expression levels were higher in TSA-treated NT than in in vitro fertilized (IVF) embryos. Data presented herein demonstrate that TSA can improve at least one epigenetic mark in early cloned bovine embryos. However, evaluation of development to full-term is necessary to ascertain whether this effect reflects a true increase in developmental potential. PMID:18419249

Iager, Amy E; Ragina, Neli P; Ross, Pablo J; Beyhan, Zeki; Cunniff, Kerrianne; Rodriguez, Ramon M; Cibelli, Jose B

2008-09-01

185

Fast macromolecular proton fraction mapping from a single off-resonance magnetization transfer measurement.  

PubMed

A new method was developed for fast quantitative mapping of the macromolecular proton fraction defined within the two-pool model of magnetization transfer. The method utilizes a single image with off-resonance saturation, a reference image for data normalization, and T(1), B(0), and B(1) maps with the total acquisition time ~10 min for whole-brain imaging. Macromolecular proton fraction maps are reconstructed by iterative solution of the matrix pulsed magnetization transfer equation with constrained values of other model parameters. Theoretical error model describing the variance due to noise and the bias due to deviations of constrained parameters from their actual values was formulated based on error propagation rules. The method was validated by comparison with the conventional multiparameter multipoint fit of the pulsed magnetization transfer model based on data from two healthy subjects and two multiple sclerosis patients. It was demonstrated theoretically and experimentally that accuracy of the method depends on the offset frequency and flip angle of the saturation pulse, and optimal ranges of these parameters are 4-7 kHz and 600°-900°, respectively. At optimal sampling conditions, the single-point method enables <10% relative macromolecular proton fraction errors. Comparison with the multiparameter fitting method revealed very good agreement with no significant bias and limits of agreement around ± 0.7%. PMID:22190042

Yarnykh, Vasily L

2012-07-01

186

Charge transfer processes and ultraviolet induced absorption in Yb:YAG single crystal laser materials  

NASA Astrophysics Data System (ADS)

Charge transfer (CT) transitions and UV induced color centers in Yb:YAG single crystals have been investigated. A simultaneous pair formation of a stable Yb2+ ion and a hole related (O-) color center (hole polaron) are observed through a CT-process. Slightly different types of hole related color centers are formed in Yb:YAG crystals containing small levels of iron impurities. Furthermore, excitation spectroscopy on the UV irradiated Yb:YAG samples could confirm an energy transfer process between Yb3+ and Yb2+ ions. The findings are important for an increased knowledge of the physical loss mechanisms observed in Yb-doped laser materials, such as the nonlinear decay process in Yb:YAG crystals as well as the photodarkening phenomenon in Yb-doped fiber lasers.

Rydberg, S.; Engholm, M.

2013-06-01

187

Regionalisation of the mouse visceral endoderm as the blastocyst transforms into the egg cylinder  

PubMed Central

Background Reciprocal interactions between two extra-embryonic tissues, the extra-embryonic ectoderm and the visceral endoderm, and the pluripotent epiblast, are required for the establishment of anterior-posterior polarity in the mouse. After implantation, two visceral endoderm cell types can be distinguished, in the embryonic and extra-embryonic regions of the egg cylinder. In the embryonic region, the specification of the anterior visceral endoderm (AVE) is central to the process of anterior-posterior patterning. Despite recent advances in our understanding of the molecular interactions underlying the differentiation of the visceral endoderm, little is known about how cells colonise the three regions of the tissue. Results As a first step, we performed morphological observations to understand how the extra-embryonic region of the egg cylinder forms from the blastocyst. Our analysis suggests a new model for the formation of this region involving cell rearrangements such as folding of the extra-embryonic ectoderm at the early egg cylinder stage. To trace visceral endoderm cells, we microinjected mRNAs encoding fluorescent proteins into single surface cells of the inner cell mass of the blastocyst and analysed the distribution of labelled cells at E5.0, E5.5 and E6.5. We found that at E5.0 the embryonic and extra-embryonic regions of the visceral endoderm do not correspond to distinct cellular compartments. Clusters of labelled cells may span the junction between the two regions even after the appearance of histological and molecular differences at E5.5. We show that in the embryonic region cell dispersion increases after the migration of the AVE. At this time, visceral endoderm cell clusters tend to become oriented parallel to the junction between the embryonic and extra-embryonic regions. Finally we investigated the origin of the AVE and demonstrated that this anterior signalling centre arises from more than a single precursor between E3.5 and E5.5. Conclusion We propose a new model for the formation of the extra-embryonic region of the egg cylinder involving a folding of the extra-embryonic ectoderm. Our analyses of the pattern of labelled visceral endoderm cells indicate that distinct cell behaviour in the embryonic and extra-embryonic regions is most apparent upon AVE migration. We also demonstrate the polyclonal origin of the AVE. Taken together, these studies lead to further insights into the formation of the extra-embryonic tissues as they first develop after implantation.

Perea-Gomez, Aitana; Meilhac, Sigolene M; Piotrowska-Nitsche, Karolina; Gray, Dionne; Collignon, Jerome; Zernicka-Goetz, Magdalena

2007-01-01

188

Spontaneous sister chromatid differentiation (SCD) and sister chromatid exchange (SCE) in mouse blastocyst chromosomes.  

PubMed

The phenomenon of spontaneous differentiation (without bromodeoxyuridine in the culture medium) of sister chromatids of mouse chromosomes at the blastocyst stage of embryogenesis is described. The frequency of sister chromatid exchanges in such differentiated chromosomes was calculated. PMID:8275704

Patkin, E L; Kustova, M E; Dyban, A P

1994-01-01

189

Observation of Frenkel and charge transfer excitons in pentacene single crystals using spectroscopic generalized ellipsometry  

NASA Astrophysics Data System (ADS)

We report on the emerging and admixture of Frenkel and charge transfer (CT) excitons near the absorption onset in pentacene single crystals. Using high energy-resolution spectroscopic generalized ellipsometry with in-plane polarization dependence, the excitonic nature of three lowest lying excitations is discussed. Their distinct polarization dependence strongly indicates the presence of both Frenkel and CT types of excitons near the excitation onset. In particular, the peculiar polarization behavior of the second excitation can only be rationalized by taking into account the inherent CT transition dipole moment. This observation has important implications for the pentacene-based optoelectronic devices.

Qi, Dongchen; Su, Haibin; Bastjan, M.; Jurchescu, O. D.; Palstra, T. M.; Wee, Andrew T. S.; Rübhausen, M.; Rusydi, A.

2013-09-01

190

Transferring and Bounding Single Photon in Waveguide Controlled by Quantum Node Based on Atomic Ensemble  

NASA Astrophysics Data System (ADS)

We study the scattering process of photons confined in a one-dimensional optical waveguide by a laser controlled atomic ensemble. The investigation leads to an alternative setup of quantum node controlling the coherent transfer of single photon in such one dimensional continuum. To exactly solve the effective scattering equations by using the discrete coordinate approach, we simulate the linear waveguide as a coupled resonator array at the high energy limit. We generally calculate the transmission coefficients and its vanishing at resonance reflects the good controllability of our scheme. We also show that there exist two bound states to describe the localize photons around the cavity.

Lu, Jing; Dong, Hui; Kuang, Le-Man

2009-09-01

191

Single scattering solution for radiative transfer through Rayleigh and aerosol atmosphere  

NASA Technical Reports Server (NTRS)

A solution is presented to the radiative transfer of the solar irradiation through a turbid atmosphere, based on the single-scattering approximation, i.e., an assumption that a photon that underwent scattering either leaves the top of the atmosphere or strikes the surface. The solution depends on a special idealization of the scattering phase function of the aerosols. The equations developed are subsequently applied to analyze quantitatively the enhancement of the surface irradiation and the enhancement of the scattered radiant emittance as seen from above the atmosphere, caused by the surface reflectance and atmospheric back scattering. An order of magnitude error analysis is presented.

Otterman, J.

1977-01-01

192

Vitrification of human blastocysts with the Hemi-Straw carrier: application of assisted hatching after thawing  

Microsoft Academic Search

BACKGROUND: The present study was undertaken to examine the usefulness of both vitrification and assisted hatching (AH) on blastocysts that originate from embryos showing different qualities during their cleavage stage. METHODS: A total of 281 blastocysts were vitrified (93 vitrification-warming cycles) in a mixture of ethylene glycol-dimethylsulphoxide-Ficoll and sucrose using the Hemi-Straw (HS) carrier system. After warming, AH using the

P. Vanderzwalmen; G. Bertin; Ch. Debauche; V. Standaert; N. Bollen; E. van Roosendaal; M. Vandervorst; R. Schoysman; N. Zech

2003-01-01

193

GLUT8 is a glucose transporter responsible for insulin-stimulated glucose uptake in the blastocyst  

Microsoft Academic Search

Mammalian preimplantation blastocysts exhibit insulin-stimulated glucose uptake despite the absence of the only known insulin-regulated transporter, GLUT4. We describe a previously unidentified member of the mammalian facilitative GLUT superfamily that exhibits 20-25% identity with other murine facilitative GLUTs. Insulin induces a change in the intracellular localization of this protein, which translates into increased glucose uptake into the blastocyst, a process

Mary O. Carayannopoulos; Maggie M.-Y. Chi; Ying Cui; Joyce M. Pingsterhaus; Robert A. McKnight; Mike Mueckler; Sherin U. Devaskar; Kelle H. Moley

2000-01-01

194

Influence of advanced age on the blastocyst development rate and pregnancy rate in assisted reproductive technology  

Microsoft Academic Search

Objective: To evaluate the percentage of blastocysts developing, the pregnancy rate, the implantation rate, and the abortion rate in women >40 years of age using a cell-free culture system for the development of viable human blastocysts.Design: Retrospective clinical study.Setting: Private IVF units.Patient(s): Two hundred ninety-three cycles in patients undergoing IVF treatment for infertility. Sixty-two cycles were in patients ?40 years

Kostas Pantos; Vasilis Athanasiou; Konstantinos Stefanidis; Dimitris Stavrou; Terpsi Vaxevanoglou; Margarita Chronopoulou

1999-01-01

195

Single crystalline BaTiO{sub 3} thin films synthesized using ion implantation induced layer transfer  

SciTech Connect

Layer transfer of BaTiO{sub 3} thin films onto silicon-based substrates has been investigated. Hydrogen and helium ions were co-implanted to facilitate ion-implantation-induced layer transfer of films from BaTiO{sub 3} single crystals. From thermodynamic equilibrium calculations, we suggest that the dominant species during cavity nucleation and growth are H{sub 2}, H{sup +}, H{sub 2}O, Ba{sup 2+} and Ba-OH, and that the addition of hydrogen to the Ba-Ti-O system can effectively suppress volatile oxide formation during layer transfer and subsequent annealing. After ion implantation, BaTiO{sub 3} layers contain microstructural defects and hydrogen precipitates in the lattice, but after layer transfer, the single crystal is found to be stoichiometric. Using direct wafer bonding and layer splitting, single crystal BaTiO{sub 3} thin films were transferred onto amorphous Si{sub 3}N{sub 4} and Pt substrates. Micro-Raman spectroscopy indicated that the density of defects generated by ion implantation in BaTiO{sub 3} can be significantly reduced during post-transfer annealing, returning the transferred layer to its single crystal state. Characterization using piezoresponse force microscopy shows that the layer transferred thin films are ferroelectric, with domain structures and piezoresponse characteristics similar to that of bulk crystals.

Park, Young-Bae; Diest, Kenneth; Atwater, Harry A. [Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125 (United States)

2007-10-01

196

Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer  

Microsoft Academic Search

We use single-molecule fluorescence lifetimes to probe dynamics of photoinduced reversible electron transfer occurring between triphenylamine (donor) and perylenediimide (acceptor) in single molecules of a polyphenylenic rigid dendrimer embedded in polystyrene. Here, reversible electron transfer in individual donor-acceptor molecules results in delayed fluorescence that is emitted with a high photon count rate. By monitoring fluorescence decay times on a photon-by-photon

Mircea Cotlet; Sadahiro Masuo; Guobin Luo; Johan Hofkens; Mark van der Auweraer; Jan Verhoeven; Klaus Müllen; Xiaoliang Sunney Xie; Frans de Schryver

2004-01-01

197

Analyses of the micromechanics of stress transfer in single- and multi-fiber pull-out tests  

Microsoft Academic Search

Analyses have been carried out on the micromechanics of elastic stress transfer taking place across the fiber\\/matrix interface in both single- and multi-fiber pull-out tests. A two-cylinder model for the single-fiber pull-out test and a three-cylinder model for the multi-fiber pull-out test were employed in order to study the fiber pull-out problems. The difference in the stress transfer between the

Shao-Yun Fu; Chee-Yoon Yue; Xiao Hu; Yiu-Wing Mai

2000-01-01

198

Observation of a single proton transfer fluorescence in a biaxially symmetric dihydroxy diflavonol  

NASA Astrophysics Data System (ADS)

The proton transfer (PT) emission of the diflavonol molecule 2,8-diphenyl-3,7-dihydroxy-4H,6H-pyrano[3,2-g]-chromene-4,6-dione (D3HF) is reported for the first time. The D3HF molecule possesses a chemical structure almost equivalent to two 3-hydroxyflavone molecules symmetrically condensed on one-benzene ring. Thus, D3HF contains two five-membered intramolecular hydrogen bonds (IMHB), and it may undergo double-PT. The discovery via experiments of the D3HF PT emission conforms to the theoretical finding, by using time-dependent (TD) density functional theory (DFT) (with the B3LYP hybrid functional), of a stable single PT tautomer either in the first excited electronic state (S 1) or in the ground electronic state. In the S 1 state, once the first single PT process occurs, the second one is hindered.

Falkovskaia, Elena; Pivovarenko, Vasyl G.; del Valle, Juan Carlos

2002-02-01

199

Large work function difference driven electron transfer from electrides to single-walled carbon nanotubes.  

PubMed

A difference in work function plays a key role in charge transfer between two materials. Inorganic electrides provide a unique opportunity for electron transfer since interstitial anionic electrons result in a very low work function of 2.4-2.6 eV. Here we investigated charge transfer between two different types of electrides, [Ca2N](+)·e(-) and [Ca24Al28O64](4+)·4e(-), and single-walled carbon nanotubes (SWNTs) with a work function of 4.73-5.05 eV. [Ca2N](+)·e(-) with open 2-dimensional electron layers was more effective in donating electrons to SWNTs than closed cage structured [Ca24Al28O64](4+)·4e(-) due to the higher electron concentration (1.3 × 10(22) cm(-3)) and mobility (?200 cm(2) V(-1) s(-1) at RT). A non-covalent conjugation enhanced near-infrared fluorescence of SWNTs as high as 52%. The field emission current density of electride-SWNT-silver paste dramatically increased by a factor of 46?000 (14.8 mA cm(-2)) at 2 V ?m(-1) (3.5 wt% [Ca2N](+)·e(-)) with a turn-on voltage of 0.85 V ?m(-1). PMID:24956225

Menamparambath, Mini Mol; Park, Jong-Ho; Yoo, Ho-Sung; Patole, Shashikant P; Yoo, Ji-Beom; Kim, Sung Wng; Baik, Seunghyun

2014-07-10

200

Microcell-mediated transfer of a single human chromosome complements xeroderma pigmentosum group A fibroblasts  

SciTech Connect

Chromosomes from an immortalized aneuploid human fibroblast cell line were randomly tagged with the selectable marker neo by transfection with the plasmid pSV2neo. Somatic cell fusions between transfected human cells and mouse A9 cells generated pools of G418-resistant human-mouse hybrid clones containing various numbers of human chromosomes. Microcell-mediated chromosome transfer from the hybrid pools to xeroderma pigmentosum complementation group A (XP-A) cells in culture and selection for G418-resistant colonies resulted in the identification of XP cells with enhanced resistance to ultraviolet radiation. Screening of subclones from selected pools of human-mouse hybrids facilitated the identification of hybrids containing a single neo-tagged human chromosome. Transfer of this chromosome to XP-A cells (but not to XP-F or XP-C cells) results in enhanced resistance to ultraviolet light and enhanced excision repair capacity. The identification of a single human chromosome that complements the phenotype of XP-A cells in culture provides the potential for genetic mapping of the complementing gene and for its isolation by molecular cloning.

Schultz, R.A.; Saxon, P.J.; Glover, T.W.; Friedberg, E.C.

1987-06-01

201

Shell thickness dependent photoinduced hole transfer in hybrid conjugated polymer/quantum dot nanocomposites: from ensemble to single hybrid level.  

PubMed

Photoinduced hole transfer is investigated in inorganic/organic hybrid nanocomposites of colloidal CdSe/ZnS quantum dots and a cationic conjugated polymer, poly(9,9'-bis(6-N,N,N-trimethylammoniumhexyl)fluorene-alt-phenylene, in solution and in solid thin film, and down to the single hybrid level and is assessed to be a dynamic quenching process. We demonstrate control of hole transfer rate in these quantum dot/conjugated polymer hybrids by using a series of core/shell quantum dots with varying shell thickness, for which a clear exponential dependency of the hole transfer rate vs shell thickness is observed, for both solution and thin-film situations. Furthermore, we observe an increase of hole-transfer rate from solution to film and correlate this with changes in quantum dot/polymer interfacial morphology affecting the hole transfer rate, namely, the donor-acceptor distance. Single particle spectroscopy experiments reveal fluctuating dynamics of hole transfer at the single conjugated polymer/quantum dot interface and an increased heterogeneity in the hole-transfer rate with the increase of the quantum dot's shell thickness. Although hole transfer quenches the photoluminescence intensity of quantum dots, it causes little or no effect on their blinking behavior over the time scales probed here. PMID:22686521

Xu, Zhihua; Hine, Corey R; Maye, Mathew M; Meng, Qingping; Cotlet, Mircea

2012-06-26

202

A real-life prospective health economic study of elective single embryo transfer versus two-embryo transfer in first IVF\\/ICSI cycles  

Microsoft Academic Search

BACKGROUND: We analysed the difference in maternal, neonatal and total costs after single (SET) versus double day 3 embryo transfer (DET). METHODS: We performed a two-centre prospective study of women in their first IVF\\/ICSI cycle choosing between SET or DET. Infertility treatment data were gathered from a database; maternal and neonatal outcome data from a case report form (CRF); health

J. Gerris; P. De Sutter; D. De Neubourg; E. Van Royen; J. Vander Elst; K. Mangelschots; M. Vercruyssen; P. Kok; M. Elseviers; L. Annemans; P. Pauwels; M. Dhont

2004-01-01

203

Transcriptomic signature to oxidative stress exposure at the time of embryonic genome activation in bovine blastocysts.  

PubMed

In order to understand how in vitro culture affects embryonic quality, we analyzed survival and global gene expression in bovine blastocysts after exposure to increased oxidative stress conditions. Two pro-oxidant agents, one that acts extracellularly by promoting reactive oxygen species (ROS) production (0.01 mM 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) or another that acts intracellularly by inhibiting glutathione synthesis (0.4 mM buthionine sulfoximine [BSO]) were added separately to in vitro culture media from Day 3 (8-16-cell stage) onward. Transcriptomic analysis was then performed on resulting Day-7 blastocysts. In the literature, these two pro-oxidant conditions were shown to induce delayed degeneration in a proportion of Day-8 blastocysts. In our experiment, no morphological difference was visible, but AAPH tended to decrease the blastocyst rate while BSO significantly reduced it, indicating a differential impact on the surviving population. At the transcriptomic level, blastocysts that survived either pro-oxidant exposure showed oxidative stress and an inflammatory response (ARRB2), although AAPH induced higher disturbances in cellular homeostasis (SERPINE1). Functional genomics of the BSO profile, however, identified differential expression of genes related to glycine metabolism and energy metabolism (TPI1). These differential features might be indicative of pre-degenerative blastocysts (IGFBP7) in the AAPH population whereas BSO exposure would select the most viable individuals (TKDP1). Together, these results illustrate how oxidative disruption of pre-attachment development is associated with systematic up-regulation of several metabolic markers. Moreover, it indicates that a better capacity to survive anti-oxidant depletion may allow for the survival of blastocysts with a quieter metabolism after compaction. PMID:23426876

Cagnone, Gael L M; Sirard, Marc-André

2013-04-01

204

Ultrafast Redistribution of E. coli SSB along Long Single-Stranded DNA via Intersegment Transfer.  

PubMed

Single-stranded DNA binding proteins (SSBs) selectively bind single-stranded DNA (ssDNA) and facilitate recruitment of additional proteins and enzymes to their sites of action on DNA. SSB can also locally diffuse on ssDNA, which allows it to quickly reposition itself while remaining bound to ssDNA. In this work, we used a hybrid instrument that combines single-molecule fluorescence and force spectroscopy to directly visualize the movement of Escherichia coli SSB on long polymeric ssDNA. Long ssDNA was synthesized without secondary structure that can hinder quantitative analysis of SSB movement. The apparent diffusion coefficient of E. coli SSB thus determined ranged from 70,000 to 170,000nt(2)/s, which is at least 600 times higher than that determined from SSB diffusion on short ssDNA oligomers, and is within the range of values reported for protein diffusion on double-stranded DNA. Our work suggests that SSB can also migrate via a long-range intersegment transfer on long ssDNA. The force dependence of SSB movement on ssDNA further supports this interpretation. PMID:24792418

Lee, Kyung Suk; Marciel, Amanda B; Kozlov, Alexander G; Schroeder, Charles M; Lohman, Timothy M; Ha, Taekjip

2014-06-26

205

Conjugate Heat Transfer Computation for Evaluation of Single-Blow Method for Compact Fin-Tube Heat Exchangers  

NASA Astrophysics Data System (ADS)

Computations have been carried out to evaluate heat transfer coefficients given by the single-blow method that is characterized by a transient and conjugate heat transfer problem between the fluid and the solid. Both heat conduction and convection equations are solved numerically to obtain the transient fluid and fin temperature distributions. Finite volume solutions indicate that the fin temperature distribution of the single-blow method varies with time and position and that the fluid temperature distribution of the single-blow method is close to that observed in the steady-state computation specified with the constant wall temperature condition. It is found that the local heat transfer coefficient resulting from the single-blow method is almost identical to that from the steady-state constant wall temperature computation and is nearly time-independent.

Song, Gil-Dal; Nishino, Koichi

206

The new Rapid-i carrier is an effective system for human embryo vitrification at both the blastocyst and cleavage stage  

PubMed Central

Background The Rapid-i is a new FDA cleared closed carrier for embryo vitrification. The cooling rate of - 1220°C/min is far lower than that reported with open vitrification systems such as the cryoloop (?15,000°C/min). Little published data is currently available on this device. This study presents our initial clinical data, as well as live birth outcomes, with the Rapid-i. The efficacy of this device for the cryopreservation of cleavage, as well as blastocyst stage human embryos is also analyzed. We further compare outcomes to those achieved with the cryoloop, an “open” vitrification system routinely used in our laboratory. Methods Human embryos were vitrified at either the 8–10 cell stage or else the blastocyst stage. The vitrification protocol was: 7.5% DMSO/7.5% ethylene glycol (EG) (2–3 min) followed by incubation in 15% DMSO /15% EG (45 sec) before loading on the vitrification carrier. Cryoprotectant was removed during warming by sequential washes in 0.25 M and 0.125 M sucrose in culture medium. Clinical outcome data for frozen cycles between January 2011 and August 2012 were stratified according to carrier and cell stage. The student t-test and chi square test were used to compare results. P value of?transferred. The clinical pregnancy rate (CPR) and implantation rate (IR) with Rapid-i vitrified blastocysts were 59% and 49%, versus 47% and 37%, respectively for cleavage stage embryos. This was not statistically different from results with the cryoloop vitrified blastocysts (CPR 46%, IR 38%) nor the cleavage stage vitrified embryos (CPR 49%, IR 35%). To date, there have been 31 deliveries of 34 healthy infants from Rapid-i vitrified embryos, with another 12 pregnancies still on-going. Conclusions The Rapid-i offers an excellent alternative to existing open vitrification devices for embryo cryopreservation at the 8–10 cell stage as well as the blastocyst stage. Use of this type of “closed” sealed system that prevents direct contact between the embryos and liquid nitrogen reduces the potential risk of sample cross-contamination or infection. These preliminary data and live birth outcomes have paved the way toward transitioning to a closed vitrification system in our own IVF program.

2013-01-01

207

Studying DNA-protein interactions with single-molecule Förster resonance energy transfer.  

PubMed

Single-molecule Förster resonance energy transfer (smFRET) has emerged as a powerful tool for elucidating biological structure and mechanisms on the molecular level. Here, we focus on applications of smFRET to study interactions between DNA and enzymes such as DNA and RNA polymerases. SmFRET, used as a nanoscopic ruler, allows for the detection and precise characterisation of dynamic and rarely occurring events, which are otherwise averaged out in ensemble-based experiments. In this review, we will highlight some recent developments that provide new means of studying complex biological systems either by combining smFRET with force-based techniques or by using data obtained from smFRET experiments as constrains for computer-aided modelling. PMID:24374460

Farooq, Shazia; Fijen, Carel; Hohlbein, Johannes

2014-03-01

208

Study of single-particle states in 23F using proton transfer reaction  

NASA Astrophysics Data System (ADS)

The proton shell structure in neutron-rich fluorine 23F was investigated using the in-beam ?-ray spectroscopy technique via the proton transfer reaction onto the unstable nucleus 22O, in addition to ? inelastic scattering on 23F, and the neutron-knockout reaction from 24F. The level and ?-decay scheme in 23F was deduced from de-excitation ?-ray-particle coincidence events. We found that a single-particle state at 4.061MeV has a large contribution from the d shell by the analysis of population strengths and the angular distribution for the state. We reported here the present experiment and the preliminary results.

Michimasa, S.; Shimoura, S.; Iwasaki, H.; Tamaki, M.; Ota, S.; Aoi, N.; Baba, H.; Iwasa, N.; Kanno, S.; Kubono, S.; Kurita, K.; Kurokawa, M.; Minemura, T.; Motobayashi, T.; Notani, M.; Ong, H. J.; Saito, A.; Sakurai, H.; Takeuchi, S.; Takeshita, E.; Yanagisawa, Y.; Yoshida, A.

2005-09-01

209

Photoinduced charge transfer and acetone sensitivity of single-walled carbon nanotube-titanium dioxide hybrids.  

PubMed

The unique physical and chemical properties of single-walled carbon nanotubes (SWNTs) make them ideal building blocks for the construction of hybrid nanostructures. In addition to increasing the material complexity and functionality, SWNTs can probe the interfacial processes in the hybrid system. In this work, SWNT-TiO2 core/shell hybrid nanostructures were found to exhibit unique electrical behavior in response to UV illumination and acetone vapors. By experimental and theoretical studies of UV and acetone sensitivities of different SWNT-TiO2 hybrid systems, we established a fundamental understanding on the interfacial charge transfer between photoexcited TiO2 and SWNTs as well as the mechanism of acetone sensing. We further demonstrated a practical application of photoinduced acetone sensitivity by fabricating a microsized room temperature acetone sensor that showed fast, linear, and reversible detection of acetone vapors with concentrations in few parts per million range. PMID:23734594

Ding, Mengning; Sorescu, Dan C; Star, Alexander

2013-06-19

210

Hemicellulose-based multifunctional macroinitiator for single-electron-transfer mediated living radical polymerization.  

PubMed

A multifunctional macroinitiator for single-electron-transfer mediated living radical polymerization (SET-LRP) was designed from acetylated galactoglucomannan (AcGGM) by ?-bromoisobutyric acid functionalization of the anomeric hydroxyl groups on the heteropolysaccharide backbone. This macroinitiator, with a degree of substitution of 0.15, was used in the SET-LRP of methyl acrylate, catalyzed by Cu(0)/Me(6)-TREN in DMSO, DMF, or DMSO/H(2)O in various concentrations. Kinetic analyses confirm high conversions of up to 99.98% and a living behavior of the SET-LRP process providing high molecular weight hemicelluloses/methyl acrylate hybrid copolymers with a brush-like architecture. PMID:21166396

Voepel, Jens; Edlund, Ulrica; Albertsson, Ann-Christine; Percec, Virgil

2011-01-10

211

Theoretical Model of the Relationship between Single Embryo Transfer Rate and Multiple Pregnancy Rate in Japan  

PubMed Central

The purpose of the present study was to examine the effect of single embryo transfer (SET) in assisted reproductive technology (ART) on the reduction of the multiple pregnancy rate. We also estimated the monozygotic (MZ) twinning rates according to the SET diffusion indirectly. A reverse sigmoid curve was assumed and examined using nationwide data of SET from 2007 to 2009 in Japan. The multiple pregnancy rate decreased almost linearly where the SET pregnancy rate was between about 40% and 80% of regression approximation. The linear approximation overestimated multiple pregnancy rates in an early period and underestimated multiple pregnancy rates in the final period. The multiple pregnancy rate seemed to be influenced by the improvement of the total pregnancy rate of ART in the early period and by the MZ twinning after SET in the final period. The estimated MZ twinning rate after SET was around 2%.

Ooki, Syuichi

2012-01-01

212

Impact of a single base pair substitution on the charge transfer rate along short DNA hairpins  

PubMed Central

Numerical studies of hole migration along short DNA hairpins were performed with a particular emphasis on the variations of the rate and quantum yield of the charge separation process with the location of a single guanine:cytosine (G:C) base pair. Our calculations show that the hole arrival rate increases as the position of the guanine:cytosine base pair shifts from the beginning to the end of the sequence. Although these results are in agreement with recent experimental findings, the mechanism governing the charge migration along these sequences is revisited here. Instead of the phenomenological two-step hopping mechanism via the guanine base, the charge propagation occurs through a delocalization of the hole density along the base pair stack. Furthermore, the variations of the charge transfer with the position of the guanine base are explained by the impact of the base pair substitutions on the delocalized conduction channels.

Renaud, Nicolas; Berlin, Yuri A.; Ratner, Mark A.

2013-01-01

213

Conformational fluctuation of Synaptotagmin-1 observed with single molecule fluorescence resonance energy transfer (smFRET)  

NASA Astrophysics Data System (ADS)

Calcium dependent neurotransmitter release at the synapses involves a synaptic vesicle protein synaptotagmin-1, a calcium sensor, to regulate exocytosis. It has been known that Synaptotagmin-1 interacts with assembled SNARE complexes, but it is unclear how their molecular mechanisms are coupled. X-ray studies in the absence of calcium revealed a closed conformation of synaptotagmin-1 and with calcium bound to the C2 domains of synaptotagmin-3 found extensive interactions holding the domains open. Suggesting the two conformations can be the key to the two functions of synaptotagmin in regulating neurotransmission. Here we use single molecule fluorescence resonance energy transfer (smFRET) to study synaptotagmin interactions with SNARE complexes and the spontaneous conformational changes of synaptotagmin-1 when calcium is induced.

Choi, Ucheor; Weninger, Keith

2008-10-01

214

Studies of the Single Particle Structure of Exotic Nuclei using Transfer Reactions  

SciTech Connect

The TIARA+VAMOS+EXOGAM set-up has recently been installed at GANIL to study the single-particle structure of exotic nuclei. The unique characteristics of the TIARA array, combined with the large acceptance spectrometer VAMOS and the high efficiency Germanium detector array EXOGAM, has allowed high-resolution measurements of transfer reactions in inverse kinematics using low intensity exotic beams. We will describe the experimental set-up, data analysis and preliminary results of the first experiments using a 24Ne beam from SPIRAL, concentrating in particular on the performance of VAMOS that has been used to detect the heavy fragments after the (d,p) (d,d) and (d,t) reactions.

Fernandez-Dominguez, B.; Chartier, M. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lemmon, R. C.; Pucknell, V. P. E.; Warner, D. D. [CCLRC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Timis, C.; Catford, W. N.; Baldwin, T. D.; Gelletly, W.; Pain, S. D. [Department of Physics, University of Surrey, Surrey GU2 7XH (United Kingdom); Labiche, M.; Amzal, N.; Burns, M.; Chapman, R.; Liang, X.; Spohr, K. [The Institute of Physical Research, University of Paisley, Paisley, PAI 2BE (United Kingdom); Ashwood, N.; Curtis, N.; Freer, M. [School of Physics and Astronomy, University of Birmingham, B15 2TT (United Kingdom); Caballero, L. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain)] (and others)

2006-04-26

215

Single breath transfer factor for carbon monoxide in an asymptomatic population of never smokers.  

PubMed Central

BACKGROUND: Data on reference values of transfer factor variables in general populations of asymptomatic never smokers are limited. The aim of this study was to examine the relation between test variables and age, height, haemoglobin concentration and carboxyhaemoglobin concentration. METHODS: Measurements of single breath transfer factor for carbon monoxide (TLCO) were obtained for a randomly selected sample of never smokers in north western Europe who were 18-73 years old and had no respiratory symptoms or disorders. Two recordings of TLCO with a ratio of inspiratory vital capacity to forced vital capacity of greater than 0.09 were obtained by standardised techniques for 304 subjects. RESULTS: The measurement errors expressed as a percentage of the common mean value of TLCO, volume adjusted TLCO (KCO), and alveolar volume (VA) were 4.5%, 4.2%, and 2.4% respectively. Multiple linear regressions showed sex specific effects of height and age on TLCO, and, in addition, of haemoglobin and carboxyhaemoglobin concentrations on KCO. VA was associated with height but not with age. The 5th and 95th centiles for TLCO and KCO in men and women were between 78% and 82% and between 120% and 127%, respectively, of predicted values when age and height were taken into account. CONCLUSION: Reference equations and normal values for transfer test variables in a large healthy population of never smokers are described in relation to age, height, and haemoglobin concentrations. To our knowledge, this is the first report of an association between carboxyhaemoglobin concentrations and KCO in a population of never smoking men and women.

Gulsvik, A; Bakke, P; Humerfelt, S; Omenaas, E; Tosteson, T; Weiss, S T; Speizer, F E

1992-01-01

216

Protein folding, protein collapse and Tanford's transfer model: Lessons from single-molecule FRET  

PubMed Central

The essential and non-trivial role of the denatured state of proteins in their folding reaction is being increasingly scrutinized in recent years. Single molecule FRET (smFRET) experiments show that the denatured state undergoes a continuous collapse (or coil-to-globule) transition as the concentration of a chemical denaturant is decreased, suggesting that conformational entropy of the denatured state is an important part of the free energy of folding. Such observations question the validity of the classical Tanford transfer model, which suggests that the folding free energy can be understood solely based on the difference in amino acid solvation between the folded state and a fixed unfolded state. An alternative to the transfer model is obtained here from a polymer theoretical analysis of a series of published smFRET data. The analysis shows that the free energy of denatured-state collapse has a linear dependence on denaturant concentration, an outcome of the interplay between enthalpic and entropic contributions. Surprisingly, the slope of the free energy of collapse agrees very well with the respective slope of the free energy of folding. This conformity of values obtained from two very different measurements shows that it is the collapse transition in the denatured state which mediates the effect of denaturants on folding. The energetics of folding are thus governed by the competition of solvation and conformational entropy in the denatured state.

Ziv, Guy; Haran, Gilad

2009-01-01

217

Single-Walled Carbon Nanotubes Alter Cytochrome C Electron Transfer and Modulate Mitochondrial Function  

PubMed Central

Single-walled carbon nanotubes (SWCNTs) are broadly used for various biomedical applications such as drug delivery, in vivo imaging and cancer photothermal therapy due to their unique physiochemical properties. However, once they enter the cells, the effects of SWCNTs to the intracellular organelles and macromolecules are not comprehensively understood. Cytochrome c (Cyt c), as a key component of the electron transport chain in mitochondria, plays an essential role in cellular energy consumption, growth and differentiation. In this study, we found the mitochondrial membrane potential (MMP) and mitochondrial oxygen uptake were greatly decreased in human epithelial KB cells treated with SWCNTs, which accompanies the reduction of Cyt c. SWCNTs deoxidized Cyt c in a pH dependent manner as evidenced by the appearance of a 550 nm characteristic absorption peak, which intensity increased as pH increase. Circular dichroism measurement confirmed the pH-dependent conformational change, which facilitated closer association of SWCNTs with the heme pocket of Cyt c and thus expedited the reduction of Cyt c. The electron transfer of Cyt c is also disturbed by SWCNTs, as measured with electron spin resonance spectroscopy. In conclusion, the redox activity of Cyt c was affected by SWCNTs treatment due to attenuated electron transfer and conformational change of Cyt c, which consequently changed mitochondrial respiration of SWCNTs treated cells. This work is significant to SWCNTs research because it provided novel understanding to the disruption of SWCNTs to the mitochondria and has important implications for biomedical applications of SWCNTs.

Ma, Xiaowei; Zhang, Li-Hua; Wang, Li-Rong; Xue, Xue; Sun, Ji-Hong; Wu, Yan; Zou, Guozhang; Wu, Xia; Wang, Paul C.; Wamer, Wayne G.; Yin, Jun-Jie; Zheng, Kaiyuan; Liang, Xing-Jie

2013-01-01

218

Modeling of heat and mass transfer during thermal decomposition of a single solid fuel particle  

NASA Astrophysics Data System (ADS)

The aim of this work was to investigate the heat and mass transfer during thermal decomposition of a single solid fuel particle. The problem regards the pyrolysis process which occurs in the absence of oxygen in the first stage of fuel oxidation. Moreover, the mass transfer during heating of the solid fuels is the basic phenomenon in the pyrolysis-derived alternative fuels (gas, liquid and solid phase) and in the gasification process which is focused on the generation of syngas (gas phase) and char (solid phase). Numerical simulations concern pyrolysis process of a single solid particle which occurs as a consequence of the particle temperature increase. The research was aimed at an analysis of the influence of particle physical properties on the devolatilization process. In the mathematical modeling the fuel grain is treated as an ideal sphere which consists of porous material (solid and gaseous phase), so as to simplify the final form of the partial differential equations. Assumption that the physical properties change only in the radial direction, reduces the partial derivatives of the angular coordinates. This leads to obtaining the equations which are only the functions of the radial coordinate. The model consists of the mass, momentum and energy equations for porous spherical solid particle heated by the stream of hot gas. The mass source term was determined in the wide range of the temperature according to the experimental data. The devolatilization rate was defined by the Arrhenius formula. The results of numerical simulation show that the heating and devolatilization time strongly depend on the physical properties of fuel. Moreover, proposed model allows to determine the pyrolysis process direction, which is limited by the equilibrium state.

Wardach-?wi?cicka, Izabela; Karda?, Dariusz

2013-06-01

219

Non-invasive imaging of human embryos before embryonic genome activation predicts development to the blastocyst stage.  

PubMed

We report studies of preimplantation human embryo development that correlate time-lapse image analysis and gene expression profiling. By examining a large set of zygotes from in vitro fertilization (IVF), we find that success in progression to the blastocyst stage can be predicted with >93% sensitivity and specificity by measuring three dynamic, noninvasive imaging parameters by day 2 after fertilization, before embryonic genome activation (EGA). These parameters can be reliably monitored by automated image analysis, confirming that successful development follows a set of carefully orchestrated and predictable events. Moreover, we show that imaging phenotypes reflect molecular programs of the embryo and of individual blastomeres. Single-cell gene expression analysis reveals that blastomeres develop cell autonomously, with some cells advancing to EGA and others arresting. These studies indicate that success and failure in human embryo development is largely determined before EGA. Our methods and algorithms may provide an approach for early diagnosis of embryo potential in assisted reproduction. PMID:20890283

Wong, Connie C; Loewke, Kevin E; Bossert, Nancy L; Behr, Barry; De Jonge, Christopher J; Baer, Thomas M; Reijo Pera, Renee A

2010-10-01

220

Kinematics of trophectoderm projections and locomotion in the peri-implantation hamster blastocyst.  

PubMed

The behavior of golden hamster blastocysts was studied in vitro by continuous time-lapse videomicrography and computer imaging, during and immediately following escape from the zona pellucida. This study revealed numerous small cytoplasmic trophectoderm projections (TEPs) approximately 18 microns long that penetrated the zona pellucida both radically and tangentially and appeared to be actively involved in zona escape in vitro. After escape from their zonae, some blastocysts moved across the culture dish by an endogenous means of locomotion, most likely involving activity of the small TEPs. Several hours after zona escape, embryos expressed large TEPs up to 46 microns long that moved in an undulating manner and showed rapid cycles of extension and retraction; the timing of their appearance suggested that these TEPs are normally involved in attachment to the uterine epithelium. Embryos fixed in utero, during the developmental interval between zona loss and embryo attachment, exhibited large TEPs similar in morphology to those expressed by cultured blastocysts. These observations document for the first time that mammalian blastocysts are capable of endogenous locomotion, confirm TEPs as components of normal blastocyst activity, reveal that there are two kinds of TEPs that differ temporally and morphologically, and extend earlier reports of TEP activity in guinea-pig embryos to the hamster. PMID:8901054

Gonzales, D S; Boatman, D E; Bavister, B D

1996-04-01

221

Atypical protein kinase C couples cell sorting with primitive endoderm maturation in the mouse blastocyst  

PubMed Central

During mouse pre-implantation development, extra-embryonic primitive endoderm (PrE) and pluripotent epiblast precursors are specified in the inner cell mass (ICM) of the early blastocyst in a ‘salt and pepper’ manner, and are subsequently sorted into two distinct layers. Positional cues provided by the blastocyst cavity are thought to be instrumental for cell sorting; however, the sequence of events and the mechanisms that control this segregation remain unknown. Here, we show that atypical protein kinase C (aPKC), a protein associated with apicobasal polarity, is specifically enriched in PrE precursors in the ICM prior to cell sorting and prior to overt signs of cell polarisation. aPKC adopts a polarised localisation in PrE cells only after they reach the blastocyst cavity and form a mature epithelium, in a process that is dependent on FGF signalling. To assess the role of aPKC in PrE formation, we interfered with its activity using either chemical inhibition or RNAi knockdown. We show that inhibition of aPKC from the mid blastocyst stage not only prevents sorting of PrE precursors into a polarised monolayer but concomitantly affects the maturation of PrE precursors. Our results suggest that the processes of PrE and epiblast segregation, and cell fate progression are interdependent, and place aPKC as a central player in the segregation of epiblast and PrE progenitors in the mouse blastocyst.

Saiz, Nestor; Grabarek, Joanna B.; Sabherwal, Nitin; Papalopulu, Nancy; Plusa, Berenika

2013-01-01

222

Efficient intramolecular energy transfer in single endcapped conjugated polymer molecules in the absence of appreciable spectral overlap.  

PubMed

Intramolecular energy transfer is investigated in an endcapped conjugated polymer on the single molecule level at low temperature. While light harvesting in one dimension is on average inefficient in the ensemble, the efficiency scatters widely on the single molecule level, with some molecules exhibiting near-unity transfer probability from the polymer backbone donor to the acceptor endcap. This transfer occurs in the absence of spectral overlap between donor and acceptor, as the electronic and vibronic transitions narrow substantially at low temperatures once inhomogeneous disorder broadening is overcome. The results illustrate how far-field absorption and emission characteristics of molecular transitions are insufficient to describe resonant energy transfer processes following Förster theory in multichromophoric aggregates. Rather, exciton trapping due to efficient multiphonon emission has to be invoked with a possible contribution of strong polaronic coupling. PMID:16417332

Becker, Klaus; Lupton, John M; Feldmann, Jochen; Setayesh, Sepas; Grimsdale, Andrew C; Müllen, Klaus

2006-01-25

223

The application of single photon detector technique in laser time transfer for Chinese navigation satellites  

NASA Astrophysics Data System (ADS)

The first Chinese mission of Laser Time Transfer (LTT) between ground and Chinese Navigation Satellites was successfully implemented by Shanghai Astronomical Observatory of Chinese Academy of Sciences. Because of LTT payloads onboard the High Earth Orbiting (HEO) satellites with orbit altitude of 21,500 to 36,000 km, the photon counting technology was adopted to increase the success rate of laser signal detection on satellites. The detection chip operates in a Geiger Mode with single photon sensitivity. It has a diameter of 40 um, it is produced by Czech Technical University. In order to reduce the background noise in space, the gated mode and two separated channels with different Field Of View (FOV) were used for the detector. The improvements for the next version of the LTT detector resulted in a lower background noise and better laser detection rate. It is also been demonstrated in the onboard experiments that the photon counting detector works well after sunlight directly entered into its optical window. Finally the LTT experiments result on Chinese Navigation Satellites are present in this paper. The clock and relative frequency difference were obtained with the single shot measuring resolution of about 300ps and 30 ps precision.

Meng, Wendong; Zhang, Haifeng; Zhang, Zhongping; Prochazka, Ivan

2013-05-01

224

Growth and charge transfer luminescence of Yb3+-doped YAlO3 single crystals  

NASA Astrophysics Data System (ADS)

Yb3+-doped YAlO3 single crystals have been grown by the Czochralski method with a radio-frequency heating system. Starting melt compositions of Y1-xYbxAlO3 were varied with x=0.02, 0.1, 0.2, 0.3, and 0.45. The best Yb3+-doped YAlO3 single crystals were obtained for a growth rate of 1.0 mm/h. The grown crystals were transparent and almost colorless. To investigate the homogeneity, the effective segregation coefficient of the Yb ion was estimated. The absorption, photoluminescence, and luminescence decay kinetics of Yb3+-doped YAlO3 were investigated for the temperature range 4-300 K. Very fast charge transfer luminescence of Yb3+ from the near ultraviolet to visible spectral range and the high density of the Yb-rich YAlO3 makes this material a promising candidate for fast scintillators.

Shim, J. B.; Yoshikawa, A.; Fukuda, T.; Pejchal, J.; Nikl, M.; Sarukura, N.; Yoon, D. H.

2004-03-01

225

Toward automated denoising of single molecular Förster resonance energy transfer data  

NASA Astrophysics Data System (ADS)

A wide-field two-channel fluorescence microscope is a powerful tool as it allows for the study of conformation dynamics of hundreds to thousands of immobilized single molecules by Förster resonance energy transfer (FRET) signals. To date, the data reduction from a movie to a final set containing meaningful single-molecule FRET (smFRET) traces involves human inspection and intervention at several critical steps, greatly hampering the efficiency at the post-imaging stage. To facilitate the data reduction from smFRET movies to smFRET traces and to address the noise-limited issues, we developed a statistical denoising system toward fully automated processing. This data reduction system has embedded several novel approaches. First, as to background subtraction, high-order singular value decomposition (HOSVD) method is employed to extract spatial and temporal features. Second, to register and map the two color channels, the spots representing bleeding through the donor channel to the acceptor channel are used. Finally, correlation analysis and likelihood ratio statistic for the change point detection (CPD) are developed to study the two channels simultaneously, resolve FRET states, and report the dwelling time of each state. The performance of our method has been checked using both simulation and real data.

Lee, Hao-Chih; Lin, Bo-Lin; Chang, Wei-Hau; Tu, I.-Ping

2012-01-01

226

Assessment of the effectiveness of nanofluids for single-phase and two-phase heat transfer in micro-channels  

Microsoft Academic Search

Experiments were performed to explore the micro-channel cooling benefits of water-based nanofluids containing small concentrations of Al2O3. The high thermal conductivity of nanoparticles is shown to enhance the single-phase heat transfer coefficient, especially for laminar flow. Higher heat transfer coefficients were achieved mostly in the entrance region of micro-channels. However, the enhancement was weaker in the fully developed region, proving

Jaeseon Lee; Issam Mudawar

2007-01-01

227

Single-phase heat transfer and pressure drop characteristics of an integral-spine-fin within an annulus  

Microsoft Academic Search

The laminar, single phase heat transfer and friction characteristics of an integral-spine-fin pipe within an annulus are presented. The heat transfer coefficient was determined using a modified version of the Wilson Plot method. The test fluid was pumped through the annulus of a straight, 3 m test section. Three fluids were investigated: (1) tap water, (2) 34% ethylene glycol\\/water mixture,

M. A. Kedzierski; M. S. Kim

1994-01-01

228

A health-economic decision-analytic model comparing double with single embryo transfer in IVF\\/ICSI  

Microsoft Academic Search

BACKGROUND: Single embryo transfer (SET) is the sole strategy with which to reduce the incidence of twins following assisted reproductive technology (ART), but SET may increase the number of ART cycles needed per live-born child. Its cost-effectiveness compared with double embryo transfer (DET) is therefore unknown. METHODS: A decision-analytic model comparing SET with DET was developed. Estimates were obtained from

Paul De Sutter; Jan Gerris; Marc Dhont

229

Kinetic energy release in thermal ion–molecule reactions: The Nb2+–(benzene) single charge–transfer reaction  

Microsoft Academic Search

We have adapted the techniques originally developed to measure ion kinetic energies in ion cyclotron resonance (ICR) spectrometry to study the single charge–transfer reaction of Nb2+ with benzene under thermal conditions in a Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). The partitioning of reaction exothermicity among the internal and translational modes available is consistent with a long-distance electron-transfer mechanism,

James R. Gorda; Ben S. Freiser; Steven W. Buckner

1991-01-01

230

Kinetic energy release in thermal ion-molecule reactions: The Nb2 + -(benzene) single charge-transfer reaction  

Microsoft Academic Search

We have adapted the techniques originally developed to measure ion kinetic energies in ion cyclotron resonance (ICR) spectrometry to study the single charge--transfer reaction of Nb{sup 2+} with benzene under thermal conditions in a Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). The partitioning of reaction exothermicity among the internal and translational modes available is consistent with a long-distance electron-transfer

James R. Gord; Ben S. Freiser; Steven W. Buckner

1991-01-01

231

Towards defining parameters for a successful single embryo transfer in frozen cycles  

Microsoft Academic Search

BACKGROUND: Twin pregnancies in IVF should be avoided by transferring embryos one at a time, even for frozen cycles. In this study, we investigated the effect of blastomere lysis and cleavage in singleton frozen embryo transfer (sFET) cycles. Outcomes were compared with the transfer of two embryos in frozen transfer cycles (dFET). METHODS: A retrospective analysis was performed on 891

R. Tang; J. Catt; D. Howlett

2006-01-01

232

Charge transfer effects, thermo and photochromism in single crystal CVD synthetic diamond.  

PubMed

We report on the effects of thermal treatment and ultraviolet irradiation on the point defect concentrations and optical absorption profiles of single crystal CVD synthetic diamond. All thermal treatments were below 850 K, which is lower than the growth temperature and unlikely to result in any structural change. UV-visible absorption spectroscopy measurements showed that upon thermal treatment (823 K), various broad absorption features diminished: an absorption band at 270 nm (used to deduce neutral single substitutional nitrogen (N(S)(0)) concentrations) and also two broad features centred at approximately 360 and 520 nm. Point defect centre concentrations as a function of temperature were also deduced using electron paramagnetic resonance (EPR) spectroscopy. Above ?500 K, we observed a decrease in the concentration of N(S)(0) centres and a concomitant increase in the negatively charged nitrogen-vacancy-hydrogen (NVH) complex (NVH(-)) concentration. Both transitions exhibited an activation energy between 0.6 and 1.2 eV, which is lower than that for the N(S)(0) donor (?1.7 eV). Finally, it was found that illuminating samples with intense short-wave ultraviolet light recovered the N(S)(0) concentration and also the 270, 360 and 520 nm absorption features. From these results, we postulate a valence band mediated charge transfer process between NVH and single nitrogen centres with an acceptor trap depth for NVH of 0.6-1.2 eV. Because the loss of N(S)(0) concentration is greater than the increase in NVH(-) concentration we also suggest the presence of another unknown acceptor existing at a similar energy to NVH. The extent to which the colour in CVD synthetic diamond is dependent on prior history is discussed. PMID:21832320

Khan, R U A; Martineau, P M; Cann, B L; Newton, M E; Twitchen, D J

2009-09-01

233

Single Rod Heat Transfer Tests to Study the Effects of Crud Deposition  

SciTech Connect

Researchers have performed many studies to try to understand crud formation on the fuel pin clad surfaces, which has been observed in pressurized water reactors (PWR) as a result of sub-cooled nucleate boiling and precipitation reactions. Crud deposits, may cause an unexpected change in core power distribution known as crud induced power shift (CIPS) or axial offset anomaly (AOA) if boron species accumulate in the deposits. If the crud deposit is thick enough, the potential exists for fuel rod surface dryout. The Westinghouse Advanced Loop Tester (WALT) at the George Westinghouse Science and Technology Center (STC) will be utilized to examine the effects of crud formation on fuel pin clad dryout. This paper describes a single heated rod test facility designed and fabricated by Westinghouse to study the effects of crud deposition at PWR reactor operating conditions. This test loop is a single rod facility with or without grid support structures on the heater rod and can be used for forced convection and sub-cooled boiling tests with and without crud deposition. Sub-cooled boiling experiments at PWR reactor operating conditions are currently being performed at this facility. The single electrical heated rod in this test facility is instrumented with four movable thermocouples to measure the inside wall temperatures at four azimuthal locations within the rod. In addition, there are two fixed thermocouples to measure the inlet and outlet temperatures of the water flowing on the outside of the heated rod such that an overall energy balance (i.e. comparing the heat absorbed by the water coolant to the measured rod electrical power) can be performed on the facility. This paper will present forced convection and boiling heat transfer curves for clean rod surfaces. Comparison with forced convection correlations and sub-cooled boiling correlations are also presented in this paper. (authors)

Wang, G.; Byers, W.A.; Karoutas, Z.E.; Young, M.Y.; Jacko, R.J. [Westinghouse Electric Company LLC. (United States); Hochreiter, L.E. [The Pennsylvania State University, 302 Walker Building, University Park, PA 16802 (United States)

2006-07-01

234

A single intravenous AAV9 injection mediates bilateral gene transfer to the adult mouse retina.  

PubMed

Widespread gene delivery to the retina is an important challenge for the treatment of retinal diseases, such as retinal dystrophies. We and others have recently shown that the intravenous injection of a self-complementary (sc) AAV9 vector can direct efficient cell transduction in the central nervous system, in both neonatal and adult animals. We show here that the intravenous injection of scAAV9 encoding green fluorescent protein (GFP) resulted in gene transfer to all layers of the retina in adult mice, despite the presence of a mature blood-eye barrier. Cell morphology studies and double-labeling with retinal cell-specific markers showed that GFP was expressed in retinal pigment epithelium cells, photoreceptors, bipolar cells, Müller cells and retinal ganglion cells. The cells on the inner side of the retina, including retinal ganglion cells in particular, were transduced with the highest efficiency. Quantification of the cell population co-expressing GFP and Brn-3a showed that 45% of the retinal ganglion cells were efficiently transduced after intravenous scAAV9-GFP injection in adult mice. This study provides the first demonstration that a single intravenous scAAV9 injection can deliver transgenes to the retinas of both eyes in adult mice, suggesting that this vector serotype is able to cross mature blood-eye barriers. This intravascular gene transfer approach, by eliminating the potential invasiveness of ocular surgery, could constitute an alternative when fragility of the retina precludes subretinal or intravitreal injections of viral vectors, opening up new possibilities for gene therapy for retinal diseases. PMID:23613884

Bemelmans, Alexis-Pierre; Duqué, Sandra; Rivière, Christel; Astord, Stéphanie; Desrosiers, Mélissa; Marais, Thibault; Sahel, José-Alain; Voit, Thomas; Barkats, Martine

2013-01-01

235

Factors affecting the efficiency of embryo transfer in the domestic ferret ( Mustela putorius furo)  

Microsoft Academic Search

Embryo transfer (ET) to recipient females is a foundational strategy for a number of assisted reproductive technologies, including cloning by somatic cell nuclear transfer. In an attempt to develop efficient ET in domestic ferrets, factors affecting development of transferred embryo were investigated. Unilateral and bilateral transfer of zygotes or blastocysts in the oviduct or uterus was evaluated in recipient nulliparous

Ziyi Li; Xingshen Sun; Juan Chen; Gregory H. Leno; John F. Engelhardt

2006-01-01

236

Repeated growth and bubbling transfer of graphene with millimetre-size single-crystal grains using platinum  

PubMed Central

Large single-crystal graphene is highly desired and important for the applications of graphene in electronics, as grain boundaries between graphene grains markedly degrade its quality and properties. Here we report the growth of millimetre-sized hexagonal single-crystal graphene and graphene films joined from such grains on Pt by ambient-pressure chemical vapour deposition. We report a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to graphene, but also to the Pt substrates. The Pt substrates can be repeatedly used for graphene growth. The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm2 V?1 s?1 under ambient conditions. The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications.

Gao, Libo; Ren, Wencai; Xu, Huilong; Jin, Li; Wang, Zhenxing; Ma, Teng; Ma, Lai-Peng; Zhang, Zhiyong; Fu, Qiang; Peng, Lian-Mao; Bao, Xinhe; Cheng, Hui-Ming

2012-01-01

237

Fluorescence resonance energy transfer between single fluorophores attached to a coiled-coil protein in aqueous solution  

Microsoft Academic Search

Fluorescence resonance energy transfer (FRET) is a technique to detect the structural changes in biomolecules. We extended this technique to the single-molecule level in aqueous solution, by combining it with total internal reflection fluorescence microscopy. Both multiple color images and fluorescence spectra at the single-molecular level were obtained to determine FRET from Cy3 to Cy5 attached to ?-tropomyosin (?Tm), a

Yoshiharu Ishii; Tomoko Yoshida; Takashi Funatsu; Tetsuichi Wazawa; Toshio Yanagida

1999-01-01

238

IGF-1\\/IGFBP-1 increases blastocyst formation and total blastocyst cell number in mouse embryo culture and facilitates the establishment of a stem-cell line  

Microsoft Academic Search

BACKGROUND: Apoptosis occurs frequently for blastocysts cultured in vitro, where conditions are suboptimal to those found in the natural environment. Insulin-like growth factor-1 (IGF-1) plays an important role in preventing apoptosis in the early development of the embryo, as well as in the progressive regulation of organ development. We hypothesize that IGF-1 and its dephosphorylated binding protein (IGFBP-1) may be

Ta-Chin Lin; Jui-Mei Yen; Kun-Bing Gong; Teng-Tsao Hsu; Lih-Ren Chen

2003-01-01

239

Single-embryo transfer reduces clinical pregnancy rates and live births in fresh IVF and Intracytoplasmic Sperm Injection (ICSI) cycles: a meta-analysis  

Microsoft Academic Search

BACKGROUND: It has become an accepted procedure to transfer more than one embryo to the patient to achieve acceptable ongoing pregnancy rates. However, transfers of more than a single embryo increase the probability of establishing a multiple gestation. Single-embryo transfer can minimize twin pregnancies but may also lower live birth rates. This meta-analysis aimed to compare current data on single-embryo

Ricardo LR Baruffi; Ana L Mauri; Claudia G Petersen; Andréia Nicoletti; Anagloria Pontes; João Batista A Oliveira; José G Franco Jr

2009-01-01

240

The use of the Brinkman number for single phase forced convective heat transfer in microchannels  

Microsoft Academic Search

From a survey on studies on convective heat transfer in microchannels, the Brinkman number is proposed as a parameter for correlating the convective heat transfer parameters in microchannels. The proposal emerges from a dimensional analysis of the variables influencing the laminar forced convection in microchannels and it can explain the unusual behaviour of convective heat transfer in the laminar regime

C. P. Tso; S. P. Mahulikar

1998-01-01

241

Performance analysis and optimization of a single barrier solid-state thermionic refrigerator with external heat transfer  

Microsoft Academic Search

A model of a single barrier solid-state thermionic refrigerator with external heat transfer is established in this paper. The performance of the refrigerator is analyzed and optimized by using the combination of finite time thermodynamics and non-equilibrium thermodynamics. The general expressions for cooling load and coefficient of performance (COP) of the refrigerator are derived. The optimum regions of cooling load

ZE-MIN DING; LIN-GEN CHEN; FENG-RUI SUN

2012-01-01

242

On-demand single-electron transfer between distant quantum dots with nanosecond pulses of surface acoustic waves  

Microsoft Academic Search

Quantum dots (QDs) provide a useful system for manipulating and storing quantum information. Methods for moving quantum information (spin) between processor and storage, or to a region of holes for conversion to photon qubits, will be required. Tunnelling of electrons over long distances between QDs is not viable. We show controlled long-range transfer of single electrons between QDs through a

R. P. G. McNeil; M. Kataoka; C. J. B. Ford; C. H. W. Barnes; J. P. Griffiths; G. A. C. Jones; I. Farrer; D. A. Ritchie

2011-01-01

243

Early cleavage is a valuable addition to existing embryo selection parameters: a study using single embryo transfers  

Microsoft Academic Search

BACKGROUND: To reduce the twin pregnancy rate, elective single embryo transfer (eSET) is increasingly implemented. Improvement of the results obtained with eSET can be achieved by better selection of the most viable embryo. This study investigated the predictive value of early cleavage (EC) as an additional parameter for selecting the embryo with the highest implantation potential by using data from

Johannes L. H. Evers

244

Current Status of Comprehensive Chromosome Screening for Elective Single-Embryo Transfer  

PubMed Central

Most in vitro fertilization (IVF) experts and infertility patients agree that the most ideal assisted reproductive technology (ART) outcome is to have a healthy, full-term singleton born. To this end, the most reliable policy is the single-embryo transfer (SET). However, unsatisfactory results in IVF may result from plenty of factors, in which aneuploidy associated with advanced maternal age is a major hurdle. Throughout the past few years, we have got a big leap in advancement of the genetic screening of embryos on aneuploidy, translocation, or mutations. This facilitates a higher success rate in IVF accompanied by the policy of elective SET (eSET). As the cost is lowering while the scale of genome characterization continues to be up over the recent years, the contemporary technologies on trophectoderm biopsy and freezing-thaw, comprehensive chromosome screening (CCS) with eSET appear to be getting more and more popular for modern IVF centers. Furthermore, evidence has showen that, by these avant-garde techniques (trophectoderm biopsy, vitrification, and CCS), older infertile women with the help of eSET may have an opportunity to increase the success of their live birth rates approaching those reported in younger infertility patients.

Wu, Ming-Yih; Chao, Kuang-Han; Chen, Chin-Der; Chang, Li-Jung; Chen, Shee-Uan; Yang, Yu-Shih

2014-01-01

245

Single-collision studies of hot atom energy transfer and chemical reaction  

SciTech Connect

This report discusses research in the collision dynamics of translationally hot atoms, with funding with DOE for the project Single-Collision Studies of Hot Atom Energy Transfer and Chemical Reaction,'' Grant Number DE-FG03-85ER13453. The work reported here was done during the period September 9, 1988 through October 31, 1991. During this period this DOE-funded work has been focused on several different efforts: (1) experimental studies of the state-to-state dynamics of the H + RH {yields} H{sub 2} R reactions where RH is CH{sub 4}, C{sub 2}H{sub 6}, or C{sub 3}H{sub 8}, (2) theoretical (quasiclassical trajectory) studies of hot hydrogen atom collision dynamics, (3) the development of photochemical sources of translationally hot molecular free radicals and characterization of the high resolution CARS spectroscopy of molecular free radicals, (4) the implementation of stimulated Raman excitation (SRE) techniques for the preparation of vibrationally state-selected molecular reactants.

Valentini, J.J. (Columbia Univ., New York, NY (United States))

1991-01-01

246

Single-collision studies of hot atom energy transfer and chemical reaction. Final report  

SciTech Connect

This report discusses research in the collision dynamics of translationally hot atoms, with funding with DOE for the project ``Single-Collision Studies of Hot Atom Energy Transfer and Chemical Reaction,`` Grant Number DE-FG03-85ER13453. The work reported here was done during the period September 9, 1988 through October 31, 1991. During this period this DOE-funded work has been focused on several different efforts: (1) experimental studies of the state-to-state dynamics of the H + RH {yields} H{sub 2} R reactions where RH is CH{sub 4}, C{sub 2}H{sub 6}, or C{sub 3}H{sub 8}, (2) theoretical (quasiclassical trajectory) studies of hot hydrogen atom collision dynamics, (3) the development of photochemical sources of translationally hot molecular free radicals and characterization of the high resolution CARS spectroscopy of molecular free radicals, (4) the implementation of stimulated Raman excitation (SRE) techniques for the preparation of vibrationally state-selected molecular reactants.

Valentini, J.J. [Columbia Univ., New York, NY (United States)

1991-12-31

247

Effect of variable thermal conductivity and viscosity on single phase convective heat transfer in slip flow  

NASA Astrophysics Data System (ADS)

For a variety of fields in which micro-mechanical systems and electronic components are used, fluid flow and heat transfer at the microscale needs to be understood and modeled with an acceptable reliability. In general, models are prepared by making some extensions to the conventional theories by including the scaling effects that become important for microscale. Some of these effects are; axial conduction, viscous dissipation, and rarefaction. In addition to these effects, temperature variable thermal conductivity and viscosity may become important in microscale gas flows due to the high temperature gradients that may exist in the fluid. For this purpose, simultaneously developing, single phase, laminar and incompressible air flow in a microtube and in the micro gap between parallel plates is numerically analyzed. Navier-Stokes and energy equations are solved and the variation of Nusselt number along the channel is presented in tabular and graphical forms as a function of Knudsen, Peclet, and Brinkman numbers, including temperature variable thermal conductivity and viscosity.

Kakaç, Sad?k; Yaz?c?o?lu, Alm?la G.; Gözükara, Arif Cem

2011-08-01

248

Linear energy transfer dependence of single event gate rupture in SiC MOS capacitors  

NASA Astrophysics Data System (ADS)

Metal-oxide-semiconductor (MOS) capacitors were fabricated on n-type 4H silicon carbide (SiC) epitaxial layers grown on n-type 4H-SiC substrates, and the currents through the gate oxide of the MOS capacitors were measured under accumulation bias conditions during heavy-ion irradiation. Evaluation of the linear energy transfer (LET) dependence of the critical electric field (Ecr) at which dielectric breakdown occurred in these capacitors revealed that the reciprocal of Ecr (1/Ecr) increased linearly with increasing LET. The slope of LET dependence of 1/Ecr for SiC is lower than that for Si, suggesting that SiC MOS devices are less susceptible to single-event gate rupture (SEGR) than Si MOS devices. The limitation of previously proposed SEGR models based on SiO2 on Si is discussed, as is the importance of the physical parameters of the oxide and semiconductor materials (bandgap, carrier lifetime and mobility, etc.).

Deki, Manato; Makino, Takahiro; Iwamoto, Naoya; Onoda, Shinobu; Kojima, Kazutoshi; Tomita, Takuro; Ohshima, Takeshi

2014-01-01

249

Collapse of a long axis: single-molecule Förster resonance energy transfer and serpin equilibrium unfolding.  

PubMed

The energy required for mechanical inhibition of target proteases is stored in the native structure of inhibitory serpins and accessed by serpin structural remodeling. The overall serpin fold is ellipsoidal with one long and two short axes. Most of the structural remodeling required for function occurs along the long axis, while expansion of the short axes is associated with misfolded, inactive forms. This suggests that ellipticity, as typified by the long axis, may be important for both function and folding. Placement of donor and acceptor fluorophores approximately along the long axis or one of the short axes allows single-pair Förster resonance energy transfer (spFRET) to report on both unfolding transitions and the time-averaged shape of different conformations. Equilibrium unfolding and refolding studies of the well-characterized inhibitory serpin ?1-antitrypsin reveal that the long axis collapses in the folding intermediates while the monitored short axis expands. These energetically distinct intermediates are thus more spherical than the native state. Our spFRET studies agree with other equilibrium unfolding studies that found that the region around one of the ? strands, s5A, which helps define the long axis and must move for functionally required loop insertion, unfolds at low denaturant concentrations. This supports a connection between functionally important structural lability and unfolding in the inhibitory serpins. PMID:24749911

Liu, Lu; Werner, Michael; Gershenson, Anne

2014-05-13

250

Dimensional feature weighting utilizing multiple kernel learning for single-channel talker location discrimination using the acoustic transfer function.  

PubMed

This paper presents a method for discriminating the location of the sound source (talker) using only a single microphone. In a previous work, the single-channel approach for discriminating the location of the sound source was discussed, where the acoustic transfer function from a user's position is estimated by using a hidden Markov model of clean speech in the cepstral domain. In this paper, each cepstral dimension of the acoustic transfer function is newly weighted, in order to obtain the cepstral dimensions having information that is useful for classifying the user's position. Then, this paper proposes a feature-weighting method for the cepstral parameter using multiple kernel learning, defining the base kernels for each cepstral dimension of the acoustic transfer function. The user's position is trained and classified by support vector machine. The effectiveness of this method has been confirmed by sound source (talker) localization experiments performed in different room environments. PMID:23363107

Takashima, Ryoichi; Takiguchi, Tetsuya; Ariki, Yasuo

2013-02-01

251

Investigating photoinduced charge transfer in double- and single-emission PbS@CdS core@shell quantum dots.  

PubMed

We present for the first time detailed investigation of the charge transfer behavior of PbS@CdS core@shell quantum dots (QDs) showing either a single emission peak from the core or intriguing double emission peaks from the core and shell, respectively. A highly non-concentric core@shell structure model was proposed to explain the origin of double emissions from monodisperse QDs. Their charge transfer behavior was investigated by monitoring photoluminescence (PL) intensity variation with the introduction of electron or hole scavengers. It was found that the PL quenching of the PbS core is more efficient than that of the CdS shell, suggesting more efficient charge transfer from the core to scavengers, although the opposite was expected. Further measurements of the PL lifetime followed by wave function calculations disclosed that the time scale is the critical factor explaining the more efficient charge transfer from the core than from the shell. The charge transfer behavior was also examined on a series of single-emission core@shell QDs with either different core sizes or different shell thicknesses and dominant factors were identified. Towards photovoltaic applications, these PbS@CdS QDs were attached onto multi-walled carbon nanotubes (MWCNTs) and their charge transfer behavior was compared with that in the PbS-QD/MWCNT system. Results demonstrate that although the CdS shell serves as an electron transfer barrier, the electrons excited in the PbS cores can still be transferred into the MWCNTs efficiently when the shell thickness is ?0.7 nm. Considering their higher stability, these core@shell QDs are very promising for the development of highly efficient QD-based photovoltaic devices. PMID:24132400

Zhao, Haiguang; Liang, Hongyan; Gonfa, Belete Atomsa; Chaker, Mohamed; Ozaki, Tsuneyuki; Tijssen, Peter; Vidal, François; Ma, Dongling

2014-01-01

252

Vitrification of mouse oocytes: improved rates of survival, fertilization, and development to blastocysts.  

PubMed

Rall and Fahy's (1985) vitrification procedure for the cryopreservation of 8-cell embryos was applied to unfertilized mouse oocytes. Unchanged, this method resulted in a mean of 24.1% of vitrified oocytes fertilizing and developing to blastocysts in vitro. Exposure of oocytes to the cryoprotectant media, but without the vitrification, resulted in 30.8% developing to blastocysts. Modifications to the durations of and media used in the dilution and equilibration steps of the procedure produced a final protocol giving a mean of 55.4% of vitrified oocytes and 72.4% of nonvitrified VS1-exposed oocytes developing to blastocysts; 85.7% of control oocytes develop to blastocysts. Osmotically induced damage was found to be the most important cause of loss of viability in these methods. Cooling of oocytes to 5-8 degrees C during the procedure had no significant effect on their viability. No parthenogenetic activation of oocytes occurred as a result of exposure to the procedure. PMID:1888516

Shaw, P W; Fuller, B J; Bernard, A; Shaw, R W

1991-08-01

253

Developmental ability of chromosomally abnormal human embryos to develop to the blastocyst stage  

Microsoft Academic Search

BACKGROUND: A correlation between morphology, developmental competence and chromosome abnormalities is established. However, since absolute correlations are rare, embryo selection remains one of the most arduous tasks in assisted reproduction. This study was undertaken in order to determine which chromosomal abnormalities are compatible with development to the blastocyst stage. METHODS: Embryos diagnosed by preimplantation genetic diagnosis (PGD) as chromosomally abnormal

M. Sandalinas; S. Sadowy; M. Alikani; G. Calderon; J. Cohen

2001-01-01

254

Superovulation induces defective methylation in line-1 retrotransposon elements in blastocyst  

PubMed Central

Background Series of epigenetic events happen during preimplantation development. Therefore assistant reproduction techniques (ART) have the potential to disrupt epigenetic regulation during embryo development. The purpose of this study was to investigate whether defects in methylation patterns in blastocyst due to superovulation originate from abnormal expression of Dnmts. Methods Low- (6 IU) and high- (10 IU) dosage of PMSG was used to stimulate the female mice. The metaphase II(MII) oocytes, zygotes and blastocyst stage embryos were collected. Global methylation and methylation at H3K9 in zygote, and methylation at repeated sequence Line 1 and IAP in blastocysts were assayed. In addition, expression of Dnmts was examined in oocytes and zygotes. Results Global DNA methylation and methylation at H3K9 in zygotes derived from females after low- or high-dosage hormone treatment were unaltered compared to that in controls. Moreover, DNA methylation at IAP in blastocysts was also unaffected, regardless of hormone dosage. In contrast, methylation at Line1 decreased when high-dose hormone was administered. Unexpectedly, expression of Dnmt3a, Dnmt3b, Dnmt3L as well as maintenance Dnmt1o in oocytes and zygotes was not disrupted. Conclusions The results suggest that defects in embryonic methylation patterns do not originate from the disruption of Dnmt expression.

2013-01-01

255

The Growth Factor Environment Defines Distinct Pluripotent Ground States in Novel Blastocyst-Derived Stem Cells  

Microsoft Academic Search

Pluripotent stem cell lines can be derived from blastocyst embryos, which yield embryonic stem cell lines (ES cells), as well as the postimplantation epiblast, which gives rise to epiblast stem cell lines (EpiSCs). Remarkably, ES cells and EpiSCs display profound differences in the combination of growth factors that maintain their pluripotent state. Molecular and functional differences between these two stem

Yu-Fen Chou; Hsu-Hsin Chen; Maureen Eijpe; Akiko Yabuuchi; Joshua G. Chenoweth; Paul Tesar; Jun Lu; Ronald D. G. McKay; Niels Geijsen

2008-01-01

256

Messenger RNAs in metaphase II oocytes correlate with successful embryo development to the blastocyst stage.  

PubMed

The mRNAs accumulated in oocytes provide support for embryo development until embryo genomic activation. We hypothesized that the maternal mRNA stock present in bovine oocytes is associated with embryo development until the blastocyst stage. To test our hypothesis, we analyzed the transcriptome of the oocyte and correlated the results with the embryo development. Our goal was to identify genes expressed in the oocyte that correlate with its ability to develop to the blastocyst stage. A fraction of oocyte cytoplasm was biopsied using micro-aspiration and stored for further expression analysis. Oocytes were activated chemically, cultured individually and classified according to their capacity to develop in vitro to the blastocyst stage. Microarray analysis was performed on mRNA extracted from the oocyte cytoplasm fractions and correlated with its ability to develop to the blastocyst stage (good quality oocyte) or arrest at the 8-16-cell stage (bad quality oocyte). The expression of 4320 annotated genes was detected in the fractions of cytoplasm that had been collected from oocytes matured in vitro. Gene ontology classification revealed that enriched gene expression of genes was associated with certain biological processes: 'RNA processing', 'translation' and 'mRNA metabolic process'. Genes that are important to the molecular functions of 'RNA binding' and 'translation factor activity, RNA binding' were also enriched in oocytes. We identified 29 genes with differential expression between the two groups of oocytes compared (good versus bad quality). The content of mRNAs expressed in metaphase II oocytes influences the activation of the embryonic genome and enables further develop to the blastocyst stage. PMID:23046986

Biase, Fernando Henrique; Everts, Robin Edward; Oliveira, Rosane; Santos-Biase, Weruska Karyna Freitas; Fonseca Merighe, Giovana Krempel; Smith, Lawrence Charles; Martelli, Lúcia; Lewin, Harris; Meirelles, Flávio Vieira

2014-02-01

257

Importance of methionine metabolism in morula-to-blastocyst transition in bovine preimplantation embryos.  

PubMed

The roles of methionine metabolism in bovine preimplantation embryo development were investigated by using ethionine, an antimetabolite of methionine. In vitro produced bovine embryos that had developed to the 5-cell stage or more at 72 h after the commencement of in vitro fertilization (IVF) were then cultured until day 8 (IVF = day 0) in medium supplemented with 0 (control), 1, 5 and 10 mM ethionine. Compared with the blastocyst development in the control (40.0%), ethionine at 10 mM almost completely blocked blastocyst development (1.1%, P<0.001), and this concentration was used in the following experiments. Methionine added at the same concentration (10 mM, a concentration control of ethionine) did not cause such an intense developmental inhibition. Development to the compacted morula stage on day 6 was not affected by 10 mM ethionine treatment. S-adenosylmethionine (SAM) added to the ethionine treatment partly restored the blastocyst development. Semiquantitative reverse transcription-polymerase chain reaction analysis of cell lineage-related transcription factors in day 6 compacted morulae showed that the expressions of NANOG and TEAD4 were increased by ethionine treatment relative to the control (P<0.01). Furthermore, immunofluorescence analysis of 5-methylcytosine revealed that DNA was hypomethylated in the ethionine-treated day 6 morulae compared with the control (P<0.001). These results demonstrate that the disruption of methionine metabolism causes impairment of the morula-to-blastocyst transition during bovine preimplantation development in part via SAM deficiency, indicating the indispensable roles of methionine during this period. The disruption of methionine metabolism may cause hypomethylation of DNA and consequently lead to the altered expression of developmentally important genes, which then results in the impairment of blastocyst development. PMID:22052008

Ikeda, Shuntaro; Sugimoto, Miki; Kume, Shinichi

2012-01-01

258

Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer  

PubMed Central

We use single-molecule fluorescence lifetimes to probe dynamics of photoinduced reversible electron transfer occurring between triphenylamine (donor) and perylenediimide (acceptor) in single molecules of a polyphenylenic rigid dendrimer embedded in polystyrene. Here, reversible electron transfer in individual donor-acceptor molecules results in delayed fluorescence that is emitted with a high photon count rate. By monitoring fluorescence decay times on a photon-by-photon basis, we find fluctuations in both forward and reverse electron transfer spanning a broad time range, from milliseconds to seconds. Fluctuations are induced by conformational changes in the dendrimer structure as well by polystyrene chain reorientation. The conformational changes are related to changes in the dihedral angle of adjacent phenyl rings located in the dendritic branch near the donor transferring the charge, a torsional motion that results in millisecond fluctuations in the “through-bond” donor-acceptor electronic coupling. Polymer chain reorientation leads to changes in the local polarity experienced by the donors and to changes in the solvation of the charge-separated state. As a result, switching between different donor moieties within the same single molecule becomes possible and induces fluctuations in decay time on a time scale of seconds.

Cotlet, Mircea; Masuo, Sadahiro; Luo, Guobin; Hofkens, Johan; Van der Auweraer, Mark; Verhoeven, Jan; Mullen, Klaus; Xie, Xiaoliang Sunney; De Schryver, Frans

2004-01-01

259

Condensation and single-phase heat transfer coefficient and flow regime visualization in microchannel tubes for HFC-134A  

NASA Astrophysics Data System (ADS)

This dissertation is to document experimental, local condensation and single-phase heat transfer and flow data of the minute diameter, microchannel tube and to develop correlation methods for optimizing the design of horizontal-microchannel condensers. It is essential to collect local data as the condensation progresses through several different flow patterns, since as more liquid is formed, the mechanism conducting heat transfer and flow is also changing. Therefore, the identification of the flow pattern is as important as the thermal and dynamic data. The experimental results were compared with correlation and flow regime maps from literature. The experiment using refrigerant HFC-134a in flat, multi-port aluminum tubing with 1.46mm hydraulic diameter was conducted. The characteristic of single-phase friction can be described with the analytical solution of square channel. The Gnielinski correlation provided good prediction of single-phase turbulent flow heat transfer. Higher mass fluxes and qualities resulted in increased condensation heat transfer and were more effective in the shear-dominated annular flow. The effect of temperature gradient from wall to refrigerant attributed profoundly in the gravity-dominated wavy/slug flow. Two correlation based on different flow mechanisms were developed for specified flow regimes. Finally, an asymptotic correlation was successfully proposed to account for the entire data regardless of flow patterns. Data taken from experiment and observations obtained from flow visualization, resulted in a better understanding of the physics in microchannel condensation, optimized designs in the microchannel condensers are now possible.

Wang, Wei-Wen William

260

Molecular adsorption on ZnO(1010) single-crystal surfaces: morphology and charge transfer.  

PubMed

While ZnO has excellent electrical properties, it has not been widely used for dye-sensitized solar cells, in part because ZnO is chemically less stable than widely used TiO(2). The functional groups typically used for surface passivation and for attaching dye molecules either bind weakly or etch the ZnO surface. We have compared the formation of molecular layers from alkane molecules with terminal carboxylic acid, alcohol, amine, phosphonic acid, or thiol functional groups on single-crystal zinc oxide (1010) surfaces. Atomic force microscopy (AFM) images show that alkyl carboxylic acids etch the surface whereas alkyl amine and alkyl alcohols bind only weakly on the ZnO(1010) surface. Phosphonic acid-terminated molecules were found to bind to the surface in a heterogeneous manner, forming clusters of molecules. Alkanethiols were found to bind to the surface, forming highly uniform monolayers with some etching detected after long immersion times in an alkanethiol solution. Monolayers of hexadecylphosphonic acid and octadecanethiol were further analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. AFM scratching shows that thiols were bound strongly to the ZnO surface, suggesting the formation of strong Zn-S covalent bonds. Surprisingly, the tridentate phosphonic acids adhered much more weakly than the monodentate thiol. The influence of organic grafting on the charge transfer to ZnO was studied by time-resolved surface photovoltage measurements and electrochemical impedance measurements. Our results show that the grafting of thiols to ZnO leads to robust surfaces and reduces the surface band bending due to midgap surface states. PMID:22680252

Chen, Jixin; Ruther, Rose E; Tan, Yizheng; Bishop, Lee M; Hamers, Robert J

2012-07-17

261

Effects of partial or complete laser-assisted hatching on the hatching of mouse blastocysts and their cell numbers  

PubMed Central

Background It is still debatable whether a full-thickness assisted hatching (AH) is better than the partial zona thinning. In this research, we used a mouse model to study the effect of partial and complete laser-AH on the rate of completely hatched blastocyst and their cell numbers. Methods In experiment 1, mouse morulae had 0, 1, 2 or 3 full-thickness openings of 10 microns created in the zona pellucida with an infrared laser beam. In the second experiment, 0, 1 and 2 openings of 20 microns were studied. In the third experiment, a full-thickness opening of 20 microns or quarter-thinning of the zonal circumference to a depth of 90% was compared with non-AH controls. Results No difference in blastocyst formation was found in laser-treated groups and in the controls. In experiment 1, the rate of completely hatched blastocysts was significantly lower than the controls. In experiment 2 when the size of the opening was increased, blastocysts completely hatched at a significantly higher rate than that in the controls. In experiment 3, the rate of completely hatched blastocysts was the highest in the full-thickness group. Cell numbers in completely hatched blastocysts from both AH groups were significantly fewer than those in the controls. Conclusions Full-thickness opening resulted in a higher rate of completely hatched blastocysts than quarter zonal-thinning and controls, but the cell numbers were significantly decreased.

2013-01-01

262

Timing of cell division in human cleavage-stage embryos is linked with blastocyst formation and quality.  

PubMed

Noninvasive markers of embryo quality are being sought to improve IVF success. The present study aimed to discover possible associations between embryo division kinetics in the cleavage stage, the subsequent ability of human embryos to reach the blastocyst stage and the resulting blastocyst morphology. A retrospective cohort study analysed 834 embryos from 165 oocyte donation couples using a time-lapse monitoring system that allowed the recording of the exact timings for key events related to embryo development. Timing parameters were categorized into four quartiles. The probability of an embryo developing to a blastocyst was linked to a strict chronology of development. To further evaluate the relationships between these morphokinetic parameters and subsequent blastocyst formation, the ensuing blastocyst morphology was compared with a viability score based on a hierarchical classification of the cleavage-stage morphokinetic parameters. It is concluded that the kinetics of early embryo development and the potential for human embryos to develop to the blastocyst stage on day 5 are closely related and that time-lapse-based evaluation of the exact timing of early events in embryo development is a promising tool for the prediction of blastocyst formation and quality according to the proposed model. PMID:22877944

Cruz, María; Garrido, Nicolás; Herrero, Javier; Pérez-Cano, Inmaculada; Muñoz, Manuel; Meseguer, Marcos

2012-10-01

263

Feasibility for a Single-Stage-to-Orbit Launch to a Geosynchronous Transfer Orbit by Pulse Laser Propulsion  

NASA Astrophysics Data System (ADS)

An air-breathing pulse laser powered launcher has been proposed as an alternative to conventional chemical launch systems. The trajectory from the ground to a geosynchronous transfer orbit by pulse laser propulsion is calculated by modeling the thrust during pulsejet, ramjet and rocket flight modes, and the launch cost is estimated. The results show that the pulse laser powered launcher can transfer 0.085kg payload per 1MW beam power to a geosynchronous orbit, and the cost becomes quarter of existing systems if one can divide a single launch into 22,500 multiple launches.

Katsurayama, Hiroshi; Komurasaki, Kimiya; Arakawa, Yoshihiro

264

Evidence of electron-transfer in the SERS spectra of a single iron-protoporphyrin IX molecule  

NASA Astrophysics Data System (ADS)

Surface enhanced Raman spectroscopy is applied to study single molecule iron-protoporphyrin IX, adsorbed on silver colloidal surfaces. If on one hand, drastic, random intensity and frequency fluctuations are observed in the Raman lines, on the other, a time dependent switching between Fe 3+ and Fe 2+ states is evidenced. Such a charge transfer, due to ballistic electrons oscillating across the molecule and the metal surface, could provide some insight on both the surface enhanced Raman mechanisms and the interfacial electron transfer in hybrid systems.

Bizzarri, Anna Rita; Cannistraro, Salvatore

2004-09-01

265

Novel HDD-type SNDM ferroelectric data storage system aimed at high-speed data transfer with single probe operation.  

PubMed

In this study, several read/write tests were conducted using a novel ferroelectric data storage test system equipped with a spindle motor, targeted at high-speed data transfer using a single probe head. A periodically inverted signal can be read out correctly with a bit rate of 100 kbps using this test system, and 10 Mbps data transfer is also possible during writing operations. The effect of a dc-offset voltage applied to the writing waveform with high-speed probe scanning is discussed. In addition, a novel noncontact probe height control technique was adopted to solve the problem of tip abrasion. PMID:18276549

Hiranaga, Yoshiomi; Uda, Tomoya; Kurihashi, Yuichi; Tanaka, Kenkou; Cho, Yasuo

2007-12-01

266

Completely ES Cell-Derived Mice Produced by Tetraploid Complementation Using Inner Cell Mass (ICM) Deficient Blastocysts.  

PubMed

Tetraploid complementation is often used to produce mice from embryonic stem cells (ESCs) by injection of diploid (2n) ESCs into tetraploid (4n) blastocysts (ESC-derived mice). This method has also been adapted to mouse cloning and the derivation of mice from induced pluripotent stem (iPS) cells. However, the underlying mechanism(s) of the tetraploid complementation remains largely unclear. Whether this approach can give rise to completely ES cell-derived mice is an open question, and has not yet been unambiguously proven. Here, we show that mouse tetraploid blastocysts can be classified into two groups, according to the presence or absence of an inner cell mass (ICM). We designate these as type a (presence of ICM at blastocyst stage) or type b (absence of ICM). ESC lines were readily derived from type a blastocysts, suggesting that these embryos retain a pluripotent epiblast compartment; whereas the type b blastocysts possessed very low potential to give rise to ESC lines, suggesting that they had lost the pluripotent epiblast. When the type a blastocysts were used for tetraploid complementation, some of the resulting mice were found to be 2n/4n chimeric; whereas when type b blastocysts were used as hosts, the resulting mice are all completely ES cell-derived, with the newborn pups displaying a high frequency of abdominal hernias. Our results demonstrate that completely ES cell-derived mice can be produced using ICM-deficient 4n blastocysts, and provide evidence that the exclusion of tetraploid cells from the fetus in 2n/4n chimeras can largely be attributed to the formation of ICM-deficient blastocysts. PMID:24733255

Wen, Duancheng; Saiz, Nestor; Rosenwaks, Zev; Hadjantonakis, Anna-Katerina; Rafii, Shahin

2014-01-01

267

Completely ES Cell-Derived Mice Produced by Tetraploid Complementation Using Inner Cell Mass (ICM) Deficient Blastocysts  

PubMed Central

Tetraploid complementation is often used to produce mice from embryonic stem cells (ESCs) by injection of diploid (2n) ESCs into tetraploid (4n) blastocysts (ESC-derived mice). This method has also been adapted to mouse cloning and the derivation of mice from induced pluripotent stem (iPS) cells. However, the underlying mechanism(s) of the tetraploid complementation remains largely unclear. Whether this approach can give rise to completely ES cell-derived mice is an open question, and has not yet been unambiguously proven. Here, we show that mouse tetraploid blastocysts can be classified into two groups, according to the presence or absence of an inner cell mass (ICM). We designate these as type a (presence of ICM at blastocyst stage) or type b (absence of ICM). ESC lines were readily derived from type a blastocysts, suggesting that these embryos retain a pluripotent epiblast compartment; whereas the type b blastocysts possessed very low potential to give rise to ESC lines, suggesting that they had lost the pluripotent epiblast. When the type a blastocysts were used for tetraploid complementation, some of the resulting mice were found to be 2n/4n chimeric; whereas when type b blastocysts were used as hosts, the resulting mice are all completely ES cell-derived, with the newborn pups displaying a high frequency of abdominal hernias. Our results demonstrate that completely ES cell-derived mice can be produced using ICM-deficient 4n blastocysts, and provide evidence that the exclusion of tetraploid cells from the fetus in 2n/4n chimeras can largely be attributed to the formation of ICM-deficient blastocysts.

Wen, Duancheng; Saiz, Nestor; Rosenwaks, Zev; Hadjantonakis, Anna-Katerina; Rafii, Shahin

2014-01-01

268

Refuting a misguided campaign against the goal of single-embryo transfer and singleton birth in assisted reproduction.  

PubMed

Much recent progress has been made by assisted reproductive technology (ART) professionals toward minimizing the incidence of multiple pregnancy following ART treatment. While a healthy singleton birth is widely considered to be the ideal outcome of such treatment, a vocal minority continues a campaign to advocate the benefits of multiple embryo transfer as treatment and twin pregnancy as outcome for most ART patients. Proponents of twinning argue four points: that patients prefer twins, that multiple embryo transfer maximizes success rates, that the costs per infant are lower with twins and that one twin pregnancy and birth is associated with no higher risk than two consecutive singleton pregnancies and births. We find fault with the reasoning and data behind each of these tenets. First, we respect the principle of patient autonomy to choose the number of embryos for transfer but counter that it has been shown that better patient education reduces their desire for twins. In addition, reasonable and evidentially supported limits may be placed on autonomy in exchange for public or private insurance coverage for ART treatment, and counterbalancing ethical principles to autonomy exist, especially beneficence (doing good) and non-maleficence (doing no harm). Second, comparisons between success rates following single-embryo transfer (SET) and double-embryo transfers favor double-embryo transfers only when embryo utilization is not comparable; cumulative pregnancy and birth rates that take into account utilization of cryopreserved embryos (and the additional cryopreserved embryo available with single fresh embryo transfer) consistently demonstrate no advantage to double-embryo transfer. Third, while comparisons of costs are system dependent and not easy to assess, several independent studies all suggest that short-term costs per child (through the neonatal period alone) are lower with transfers of one rather than two embryos. And, finally, abundant evidence conclusively demonstrates that the risks to both mother and especially to children are substantially greater with one twin birth compared with two singleton births. Thus, the arguments used by some to promote multiple embryo transfer and twinning are not supported by the facts. They should not detract from efforts to further promote SET and thus reduce ART-associated multiple pregnancy and its inherent risks. PMID:23904468

Stillman, Robert J; Richter, Kevin S; Jones, Howard W

2013-10-01

269

Convective Heat Transfer for Single-Phase Gases in Microchannel Slip Flow: Analytical Solutions  

Microsoft Academic Search

Heat transfer in microchannels has gained more interest in the last decade due to developments in the aerospace, biomedical and electronics industries. It has been a critical issue since the performance of the devices is primarily determined by temperature. As the size decreases, more efficient ways of cooling are sought due to the reduction in the heat transfer area. Convection

Y. Bayazitoglu; G. Tunc; K. Wilson; I. Tjahjono

270

[How can we nowadays select the best embryo to transfer?].  

PubMed

Multiple pregnancies stand as the most common adverse outcome of assisted reproduction technologies (ART) and the dangers associated with those pregnancies have been reduced by doing elective single embryo transfers (e-SET). Many studies have shown that e-SET is compatible with a continuously high pregnancy rate per embryo transfer. Yet, it still becomes necessary to improve the selection process in order to define the quality of individual embryos - so that the ones we choose for transfer are more likely to implant. First, analysis of embryo morphology has greatly helped in this identification and remains the most relevant criterion for choosing the embryo. The introduction of time-lapse imaging provides new criteria predictive of implantation potential, but the real contribution of this system - including the benefit/cost ratio - seems to be not yet properly established. In this context, extended culture until blastocyst stage is an essential practice but it appears wise to keep it for a population showing a good prognosis. Then, the failure of aneuploid embryos to implant properly led to achieve preimplantation genetic screening (PGS) in order to increase pregnancy and delivery rates after ART. However, PGS by fluorescence in situ hybridization (FISH) at day 3 is a useless process - and may even be harmful. Another solution involves using comparative genomic hybridisation (CGH) and moving to blastocyst biopsy. Finally, it is envisaged that morphology will also be significantly aided by non-invasive analysis of biomarkers in the culture media that give a better reflection of whole-embryo physiology and function. PMID:24951187

Alter, L; Boitrelle, F; Sifer, C

2014-01-01

271

Single-molecule fluorescence spectroscopy studies of photo-induced electron transfer between CdSe/ZnS quantum dots and fullerene  

NASA Astrophysics Data System (ADS)

Photo-induced electron transfer in CdSe/ZnS semiconductor quantum dot-fullerene conjugates was investigated by single molecule fluorescence spectroscopy. The average rate for photoinduced electron transfer is estimated around 108s-1. Quenching by electron transfer is observed in the "on" state and it manifests both as reduced fluorescence intensity and as shortening in fluorescence lifetime. As a result, the electron transfer changes the on/off dynamics of the fluorescence intensity of individual quantum dots.

Xu, Zhihua; Cotlet, Mircea

2010-02-01

272

Manipulation of the transport properties of single-walled nanotubes by alkali intercalation and local charge transfer  

NASA Astrophysics Data System (ADS)

We have studied the effects of charge transfer on the transport properties of individual single-walled nanotubes. This was done in two ways. In the first, we expose devices made of individual nanotubes to alkali metal vapor. This causes no change in the conductance of devices made of metallic tubes, while it increases the conductance of semiconducting tubes and causes them to change from p-type to n-type. In the second method, we examine a single semiconducting nanotube over three leads with an impurity particle near one lead. Local charge transfer from the impurity to the tube causes the region with the impurity to act as a diode, while the other, `clean', half displays symmetric transport behavior.

Hone, J.; Antonov, Radoslav; Johnson, A. T.; Bockrath, Marc; McEuen, Paul L.; Zettl, A.

1999-09-01

273

Performance Analysis and Optimization of a Single-Barrier Solid-State Thermionic Refrigerator With External Heat Transfer  

Microsoft Academic Search

A model of a single-barrier solid-state thermionic refrigerator with external heat transfer is established in this paper. The performance of the refrigerator is analyzed and optimized by using the combination of finite-time thermodynamics and nonequilibrium thermodynamics. The general expressions for cooling load and coefficient of performance (COP) of the refrigerator are derived. The optimum regions of cooling load and COP

Ze-Min Ding; Lin-Gen Chen; Feng-Rui Sun

2012-01-01

274

Experimental and numerical study of pressure drop and heat transfer in a single-phase micro-channel heat sink  

Microsoft Academic Search

The pressure drop and heat transfer characteristics of a single-phase micro-channel heat sink were investigated both experimentally and numerically. The heat sink was fabricated from oxygen-free copper and fitted with a polycarbonate plastic cover plate. The heat sink consisted of an array of rectangular micro-channels 231?m wide and 713?m deep. Deionized water was employed as the cooling liquid and two

Weilin Qu; Issam Mudawar

2002-01-01

275

Studies on the structure and dynamics of the human telomeric G quadruplex by single-molecule fluorescence resonance energy transfer  

Microsoft Academic Search

We have investigated the structure and unfolding kinetics of the human telomeric intramolecular G quadruplex by using single-molecule fluorescence resonance energy transfer. An exploration of conformational heterogeneity revealed two stable folded conformations, in both sodium- and potassium-containing buffers, with small differences between their enthalpies and entropies. Both folded conformations can be opened by the addition of a 21-base complementary DNA

Liming Ying; Jeremy J. Green; Haitao Li; David Klenerman; Shankar Balasubramanian

2003-01-01

276

Mothers, Workers and Students: Examining the Experiences of Single Mothers Transferring from Community Colleges into Universities  

ERIC Educational Resources Information Center

Single parent households are on the rise, and female headed households are more likely to live in poverty than other single parent households (Holyfield, 2002). Many single mothers who do not have an undergraduate degree see education as a way out of poverty (Holyfield, 2002; Heller & Bjorklund, 2004). This research was undertaken to highlight…

Robinson, Emily Erin Peterson

2010-01-01

277

Thermal visualization of heat-transfer characteristics for single impinging jet  

NASA Astrophysics Data System (ADS)

The local heat-transfer characteristics of an impingement-cooling jet are presently ascertained, for cases with and without crossflow, through the use of a combined metal heating-element and cholesteric liquid crystal system. The results obtained indicate that the impingement Nusselt numbers of double-peak values increase with rising jet Reynolds number. A moving cylindrical jet-source model is used to simulate and analyze the jet's impingement heat transfer.

Li, Liguo; Zhu, Yun; Zhang, Jingzhou; Yu, Wei

278

Introduction of blastocyst culture and transfer for all patients in an in vitro fertilization program  

Microsoft Academic Search

Objective: To evaluate the nonselective application of extended embryo culture on the outcome of IVF.Design: Retrospective analysis.Setting: Private practice assisted reproductive technology center.Patient(s): Seven hundred ninety nonselected patients undergoing IVF with controlled ovarian stimulation.Intervention(s): For day 3 ET, multicell embryos were cultured in human tubal fluid medium and 12% synthetic serum substitute. For day 5 ET, embryos were cultured for

Del Marek; Martin Langley; David K Gardner; Nils Confer; Kathleen M Doody; Kevin J Doody

1999-01-01

279

Stage of susceptibility to carcinogenicity of prenatal dietary fat exposure tested by blastocyst transfer  

Microsoft Academic Search

A previous experiment with exposure of female mice to a diet high in fat from 4 weeks of age through to the end of pregnancy demonstrated a substantial increase in the frequency of reproductive system tumors in their female offspring. Over this wide period of exposure, one or more specific periods of sensitivity to the carcinogenic effects of dietary fat

Bruce E. Walker; Mian Zhou

1997-01-01

280

Effects of donor fibroblasts expressing OCT4 on bovine embryos generated by somatic cell nuclear transfer.  

PubMed

The production of healthy, live, cloned animals by somatic cell nuclear transfer (SCNT) has been hampered by low efficiencies. Significant epigenetic changes must take place to ensure proper chromatin remodeling in SCNT. We hypothesized that exogenous expression of OCT4 in donor fibroblasts prior to its fusion with enucleated oocytes would facilitate SCNT reprogramming. We infected bovine adult fibroblasts with retroviral vectors containing yellow fluorescent protein (YFP) only, or the OCT4 gene fused to YFP (YO). We found that development to the blastocyst stage was not different between NT-YFP and NT-YO groups. NT-YFP embryos had the fewest trophoblast cells, measured by numbers of CDX2-positive cells. Fibroblasts expressing OCT4 had reduced levels of histone 3 lysine 9 or 27 trimethylation (H3K9me3 and H3K27me3, respectively). NT-YO blastocysts displayed higher H3K9me3 levels than IVF and NT-YFP embryos; however, they did not have different H3K27me3 levels. Levels of XIST mRNA expression in NT-YO and NT-YF were higher when compared to in vitro-fertilized blastocysts. We observed no differences in the expression of SOX2, NANOG, and CDX2. Although overexpression of OCT4 in donor cells increased H3K9me3 and did not reduce XIST gene expression, we show that a single transcription factor can affect the number of trophectoderm cells in bovine SCNT embryos. PMID:23276226

Goissis, Marcelo D; Suhr, Steven T; Cibelli, Jose B

2013-02-01

281

Cloned calves derived from somatic cell nuclear transfer embryos cultured in chemically defined medium or modified synthetic oviduct fluid.  

PubMed

Somatic cell nuclear transfer (SCNT) is considered to be a critical tool for propagating valuable animals. To determine the productivity calves resulting from embryos derived with different culture media, enucleated oocytes matured in vitro were reconstructed with fetal fibroblasts, fused, and activated. The cloned embryos were cultured in modified synthetic oviduct fluid (mSOF) or a chemically defined medium (CDM) and developmental competence was monitored. After 7 days of culturing, the blastocysts were transferred into the uterine horn of estrus-synchronized recipients. SCNT embryos that were cultured in mSOF or CDM developed to the blastocysts stages at similar rates (26.6% vs. 22.5%, respectively). A total of 67 preimplantational stage embryos were transferred into 34 recipients and six cloned calves were born by caesarean section, or assisted or natural delivery. Survival of transferred blastocysts to live cloned calves in the mSOF and the CDM was 18.5% (to recipients), 9.6% (to blastocysts) and 42.9% (to recipients), 20.0% (to blastocysts), respectively. DNA analysis showed that all cloned calves were genetically identical to the donor cells. These results demonstrate that SCNT embryos cultured in CDM showed higher viability as judged by survival of the calves that came to term compared to blastocysts derived from mSOF cultures. PMID:21368567

Jang, Goo; Hong, So Gun; Lee, Byeong Chun

2011-03-01

282

Cloned calves derived from somatic cell nuclear transfer embryos cultured in chemically defined medium or modified synthetic oviduct fluid  

PubMed Central

Somatic cell nuclear transfer (SCNT) is considered to be a critical tool for propagating valuable animals. To determine the productivity calves resulting from embryos derived with different culture media, enucleated oocytes matured in vitro were reconstructed with fetal fibroblasts, fused, and activated. The cloned embryos were cultured in modified synthetic oviduct fluid (mSOF) or a chemically defined medium (CDM) and developmental competence was monitored. After 7 days of culturing, the blastocysts were transferred into the uterine horn of estrus-synchronized recipients. SCNT embryos that were cultured in mSOF or CDM developed to the blastocysts stages at similar rates (26.6% vs. 22.5%, respectively). A total of 67 preimplantational stage embryos were transferred into 34 recipients and six cloned calves were born by caesarean section, or assisted or natural delivery. Survival of transferred blastocysts to live cloned calves in the mSOF and the CDM was 18.5% (to recipients), 9.6% (to blastocysts) and 42.9% (to recipients), 20.0% (to blastocysts), respectively. DNA analysis showed that all cloned calves were genetically identical to the donor cells. These results demonstrate that SCNT embryos cultured in CDM showed higher viability as judged by survival of the calves that came to term compared to blastocysts derived from mSOF cultures.

Hong, So Gun

2011-01-01

283

Effects of lead on the male mouse as investigated by in vitro fertilization and blastocyst culture  

SciTech Connect

Long-term exposure of male mice to inorganic lead (lead chloride, 1 g/liter) in the drinking water reduces their fertility. The cause of this reduction, expressed as a decrease in the number of mated females showing inplantations, was investigated, using an in vivo fertilization method. It was found that spermatozoa from lead-exposed males had a significantly lower ability to fertilize mouse eggs than those from unexposed males. Preimplantation embryos, isolated from uterine horns of mice mated with lead-exposed males. Preimplantation embryos, isolated from uterine horns of mice mated with lead-exposed males, were examined. No morphologically abnormal embryos were found. However, when cultured in vitro over the implantation period, blastocysts of the group mated with lead-exposed males showed an increased frequency of delayed hatching from the zona pellucida or an inability to hatch. Among blastocysts from this group a decreased frequency of inner cell mass development was also found.

Johansson, L.; Sjoeblom, P.; Wide, M.

1987-02-01

284

The 'GO' system--a novel method of microculture for in vitro development of mouse zygotes to the blastocyst stage  

Microsoft Academic Search

An ovel system of in vitro culture termed the 'glass oviduct' or 'GO' culture system is described. Mouse zygotes were cultured in pairs to the blastocyst stage in open-ended 1 l glass capillaries. 'GO' culture supported the development of significantly more hatching or hatched blastocysts than did a standard microdroplet (10 zygotes per 20 l) control culture (48.3 versus 3.3%,

G. A. Thouas; G. M. Jones; A. O. Trounson

2003-01-01

285

Effect of culture system on the yield and quality of bovine blastocysts as assessed by survival after vitrification  

Microsoft Academic Search

The aim of this study was to assess the effect of a bovine in vitro culture system on blastocyst yield and quality after vitrification. In Experiment 1, IVM\\/IVF zygotes were cultured in either synthetic oviduct fluid (SOF) in 5% CO2, 5% O2, 90% N2; or TCM199-granulosa cells (TCM199-GCM) in 5% CO2 in air. In vivo blastocysts were used as a

D. Rizos; F. Ward; M. P. Boland; P. Lonergan

2001-01-01

286

Successful development of viable blastocysts from enhanced green fluorescent protein transgene-microinjected mouse embryos: Comparison of culture media  

Microsoft Academic Search

To improve efficiency of trans- genesis, we compared M16 and CZB embryo culture media, supporting development to blastocysts of FVB\\/ N mouse pronuclear-eggs, microinjected with enhanc- ed green fluorescent protein (EGFP) transgene. When EGFP-injected-eggs were cultured (120 hr), blastocyst development was significantly (P < 0.03) higher in M16 medium (72.5 ? 2.4%) than that in CZB (13.2 ? 4.3%) or

Vikram Devgan; Polani B. Seshagiri

2003-01-01

287

RAG2Deficient Blastocyst Complementation: An Assay of Gene Function in Lymphocyte Development  

Microsoft Academic Search

We describe a system to evaluate the function of lymphocyte-specific and generally expressed genes in the differentiation and\\/or function of lymphocytes. RAG-2 (recombination-activating gene 2)-deficient mice have no mature B and T lymphocytes due to the inability to initiate VDJ recombination. Blastocysts from RAG-2-deficient mice generate animals with no mature B and T cells following implantation into foster mothers. However,

Jianzhu Chen; Russell Lansford; Valerie Stewart; Faith Young; Frederick W. Alt

1993-01-01

288

Innate immunity in an in vitro murine blastocyst model using embryonic and trophoblast stem cells.  

PubMed

The immune system has two broad components-innate and adaptive immunity. Adaptive immunity becomes established only after the onset of hematopoiesis, whereas the innate immune system may be actively protecting organisms from microbial invasion much earlier in development. Here, we address the question of whether the innate immune system functions in the early-stage embryo, i.e., the blastocyst. The innate immune system was studied by using in vitro blastocyst models, e.g., embryonic stem (ES) and trophoblast stem (TS) cell cultures. The expression of Toll-like receptors (TLR)-2, -3, and -5 could be detected in both ES and TS cells. The expression of interferon (IFN)-? was induced by the addition of polyinosinic:polycytidylic acid [poly(I:C)] in TS cells, but not ES cells, although TLR-3 was expressed at the same level in both cell types. In turn, ES cells responded to IFN-? exposure by expressing IFN-induced anti-viral genes, e.g., RNA-dependent protein kinase and 2', 5'-oligoadenylate synthetase (OAS). Neither a reduction in ES cell proliferation nor cell death in these cultures was observed after IFN-? stimulation. Furthermore, OAS1a expression was induced in ES/TS co-cultures after poly(I:C) stimulation, but was not induced when either cell type was cultured alone. In conclusion, TS cells react to poly(I:C) stimulation by producing IFN-?, which induces IFN-inducible genes in ES cells. This observation suggests that the trophectoderm, the outer layer of the blastocyst, may respond to viral infection, and then induce anti-viral gene expression via IFN-? signaling to the blastocyst inner cell mass. PMID:24113362

Aikawa, Hiroaki; Tamai, Miho; Mitamura, Keisuke; Itmainati, Fakhria; Barber, Glen N; Tagawa, Yoh-ichi

2014-03-01

289

Ammonium exposure and pyruvate affect the amino acid metabolism of bovine blastocysts in vitro  

Microsoft Academic Search

The accumulation of ammonium is a major artefact of in vitro embryo culture. This study has examined ammonium production and potential mechanisms of disposal in preimplantation bovine blastocysts. Embryos were produced by in vitro maturation and fertilisation of oocytes, and cultured in synthetic oviduct fluid containing amino acids and BSA (SOFaaBSA). Ammonium\\/urea concentrations were determined enzymatically. Amino acid appearance\\/disappearance 'profiles'

Nicolas M Orsi; Henry J Leese

2004-01-01

290

Chimaerism and erythroid marker expression after microinjection of human acute myeloid leukaemia cells into murine blastocysts  

Microsoft Academic Search

It has been suggested that the embryonic microenvironment can control the survival and the transformed phenotype of tumour cells. Here, we addressed the hypothesis that the murine embryonic microenvironment can induce the differentiation of human tumour cells. To examine such interactions, we injected human leukaemic cells into preimplantation murine blastocysts at embryonic day 3.5 of gestation (E3.5). Microinjection of human

Michael Dürr; Friedrich Harder; Angela Merkel; Gesine Bug; Reinhard Henschler; Albrecht M Müller

2003-01-01

291

Quantifying the biomechanics of conception: L-selectin-mediated blastocyst implantation mechanics with engineered "trophospheres".  

PubMed

An estimated 12% of women in the United States suffer from some form of infertility. In vitro fertilization (IVF) is the most common treatment for infertility encompassing over 99% of all assisted reproductive technologies. However, IVF has a low success rate. Live birth rates using IVF can range from 40% in women younger than 35 years to 4% in women older than 42 years. Costs for a successful IVF outcome can be upward of $61,000. The low success rate of IVF has been attributed to the inability of the blastocyst to implant to the uterus. Blastocyst implantation is initiated by L-selectin expressing cells, trophoblasts, binding to L-selectin ligands, primarily sialyl Lewis X (sLeX), on the uterine surface endometrium. Legal and ethical considerations have limited the research on human subjects and tissues, whereas animal models are costly or do not properly mimic human implantation biochemistry. In this work, we describe a cellular model system for quantifying L-selectin adhesion mechanics. L-selectin expression was confirmed in Jeg-3, JAR, and BeWo cell lines, with only Jeg-3 cells exhibiting surface expression. Jeg-3 cells were cultured into three-dimensional spheres, termed "trophospheres," as a mimic to human blastocysts. Detachment assays using a custom-built parallel plate flow chamber show that trophospheres detach from sLeX functionalized slides with 2.75 × 10(-3) dyn of force and 7.5 × 10(-5) dyn-cm of torque. This work marks the first time a three-dimensional cell model has been utilized for quantifying L-selectin binding mechanics related to blastocyst implantation. PMID:23927766

Yucha, Robert W; Jost, Monika; Rothstein, Dianne; Robertson, Noreen; Marcolongo, Michele S

2014-01-01

292

Bivariate analysis of basal serum anti-Müllerian hormone measurements and human blastocyst development after IVF  

Microsoft Academic Search

BACKGROUND: To report on relationships among baseline serum anti-Müllerian hormone (AMH) measurements, blastocyst development and other selected embryology parameters observed in non-donor oocyte IVF cycles.\\u000aMETHODS: Pre-treatment AMH was measured in patients undergoing IVF (n = 79) and retrospectively correlated to in vitro embryo development noted during culture.\\u000aRESULTS: Mean (+\\/- SD) age for study patients in this study group

Eric Scott Sills; Gary S Collins; Adam C Brady; David J Walsh; Kevin D Marron; Alison C Peck; Anthony PH Walsh; Rifaat D Salem

2011-01-01

293

DFT/B3LYP study of the substituent effect on the reaction enthalpies of the individual steps of single electron transfer-proton transfer and sequential proton loss electron transfer mechanisms of phenols antioxidant action.  

PubMed

The reaction enthalpies related to the individual steps of two phenolic antioxidants action mechanisms, single electron transfer-proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET), for 30 meta and para-substituted phenols (ArOH) were calculated using DFT/B3LYP method. These mechanisms represent the alternative ways to the extensively studied hydrogen atom transfer (HAT) mechanism. Except the comparison of calculated reaction enthalpies with available experimental and/or theoretical values, obtained enthalpies were correlated with Hammett constants. We have found that electron-donating substituents induce the rise in the enthalpy of proton dissociation (PDE) from ArOH+* radical cation (second step in SET-PT) and in the proton affinities of phenoxide ions ArO- (reaction enthalpy of the first step in SPLET). Electron-withdrawing groups cause the increase in the reaction enthalpies of the processes where electron is abstracted, i.e., in the ionization potentials of ArOH (first step in SET-PT) and in the enthalpy of electron transfer from ArO- (second step in SPLET). Found results indicate that all dependences of reaction enthalpies on Hammett constants of the substituents are linear. The calculations of liquid-phase reaction enthalpies for several para-substituted phenols indicate that found trends hold also in water, although substituent effects are weaker. From the thermodynamic point of view, entering SPLET mechanism represents the most probable process in water. PMID:17078630

Klein, Erik; Lukes, Vladimír

2006-11-01

294

Use of coisogenic host blastocysts for efficient establishment of germline chimeras with C57BL/6J ES cell lines.  

PubMed

Gene targeting in embryonic stem (ES) cells allows the production of mice with specified genetic mutations. Currently, germline-competent ES cell lines are available from only a limited number of mouse strains, and inappropriate ES cell/host blastocyst combinations often restrict the efficient production of gene-targeted mice. Here, we describe the derivation of C57BL/6J (B6) ES lines and compare the effectiveness of two host blastocyst donors, FVB/NJ (FVB) and the coisogenic strain C57BL/6-Tyr(c)-2J (c2J), for the production of germline chimeras. We found that when B6 ES cells were injected into c2J host blastocysts, a high rate of coat-color chimerism was detected, and germline transmission could be obtained with few blastocyst injections. In all but one case, highly chimeric mice transmitted to 100% of their offspring. The injection of B6 ES cells into FVB blastocysts produced some chimeric mice. However; the proportion of coat-color chimerism was low, with many more blastocyst injections required to generate chimeras capable of germline transmission. Our data support the use of the coisogenic albino host strain, c2J, for the generation of germline-competent chimeric mice when using B6 ES cells. PMID:11730008

Schuster-Gossler, K; Lee, A W; Lerner, C P; Parker, H J; Dyer, V W; Scott, V E; Gossler, A; Conover, J C

2001-11-01

295

Survival and apoptosis rates after vitrification in cryotop devices of in vitro-produced calf and cow blastocysts at different developmental stages.  

PubMed

Two experiments were designed to determine the ability of in vitro-cultured blastocysts at different stages of development to survive the vitrification procedure using cryotop devices. Day 7 and Day 8 embryos were classified as non-expanded, expanded or hatching and/or hatched blastocysts. In the first experiment, we examined the survival rate of vitrified-warmed blastocysts after 3 h incubation in synthetic oviducal fluid (SOF) medium. In the second experiment, vitrified-warmed blastocysts were evaluated using the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) technique to detect nuclei with damaged DNA. In both experiments, results for cow and calf blastocysts were compared. No differences in survival rates were observed after vitrification of Day 8 expanded (52.4%) and hatched (50%) cow blastocysts or Day 8 expanded (54.5%) and hatched (59.4%) calf blastocysts. When embryos were vitrified on Day 7, survival rates of 78.4% and 66.7% were observed after warming expanded and hatched cow blastocysts, respectively, compared with rates of 80% and 76.9%, respectively, for calf blastocysts. Lowest survival rates were recorded for non-expanded blastocysts (26%-54%) compared with the other developmental stages, particularly those vitrified at Day 8 (blastocysts, regardless of the length of embryo culture, the developmental stage of the embryo or the source of the oocytes. Our findings suggest that the cryotop vitrification method is particularly useful for the cryopreservation of blastocysts presenting with a high degree of expansion (expanded or hatched blastocysts), particularly when vitrification is performed after 7 days of in vitro embryo culture. PMID:20797352

Morató, Roser; Izquierdo, Dolors; Paramio, Maria Teresa; Mogas, Teresa

2010-01-01

296

Ovarian Stimulation by Exogenous Gonadotropin Decreases the Implantation Rate and Expression of Mouse Blastocysts Integrins  

PubMed Central

Background: Integrins are heterodimeric glycoprotein receptors that regulate the interaction of cells with extracellular matrix and may have a critical role in implantation. The aim of this study was to investigate the effect of ovulation induction on the expression of ?4, ?v, ?1, and ?3 integrins in mouse blastocyst at the time of implantation. Methods: The ovarian stimulated and non-stimulated pregnant mice were sacrificed on the morning of 5th day of pregnancy. The blastocysts were collected, and the expression of ?v, ?4, ?1, and ?3 integrins was examined using real-time RT-PCR and immunocytochemical techniques, then their ovarian hormones were analyzed at the same time. The implantation sites in uterine horns of other pregnant mice in both groups were determined under a stereomicroscope on the 7th day of pregnancy. Results: The results showed that the expression of ?v, ?1, and ?3 integrins in both mRNA and protein levels was significantly lower in the ovarian stimulated group than the control group, and the maximum ratio of expression was belonged to ?1 molecule (P>0.05). Conclusion: The implantation rate in superovulated mice was significantly lower than control mice. It was suggested that ovulation induction decreased the expression of ?v, ?1, and ?3 integrins of mouse blastocysts.

Fayazi, Mehri; Beigi Boroujeni, Mandana; Salehnia, Mojdeh; Khansarinejad, Behzad

2014-01-01

297

Investigating photoinduced charge transfer in double- and single-emission PbS@CdS core@shell quantum dots  

NASA Astrophysics Data System (ADS)

We present for the first time detailed investigation of the charge transfer behavior of PbS@CdS core@shell quantum dots (QDs) showing either a single emission peak from the core or intriguing double emission peaks from the core and shell, respectively. A highly non-concentric core@shell structure model was proposed to explain the origin of double emissions from monodisperse QDs. Their charge transfer behavior was investigated by monitoring photoluminescence (PL) intensity variation with the introduction of electron or hole scavengers. It was found that the PL quenching of the PbS core is more efficient than that of the CdS shell, suggesting more efficient charge transfer from the core to scavengers, although the opposite was expected. Further measurements of the PL lifetime followed by wave function calculations disclosed that the time scale is the critical factor explaining the more efficient charge transfer from the core than from the shell. The charge transfer behavior was also examined on a series of single-emission core@shell QDs with either different core sizes or different shell thicknesses and dominant factors were identified. Towards photovoltaic applications, these PbS@CdS QDs were attached onto multi-walled carbon nanotubes (MWCNTs) and their charge transfer behavior was compared with that in the PbS-QD/MWCNT system. Results demonstrate that although the CdS shell serves as an electron transfer barrier, the electrons excited in the PbS cores can still be transferred into the MWCNTs efficiently when the shell thickness is ~0.7 nm. Considering their higher stability, these core@shell QDs are very promising for the development of highly efficient QD-based photovoltaic devices.We present for the first time detailed investigation of the charge transfer behavior of PbS@CdS core@shell quantum dots (QDs) showing either a single emission peak from the core or intriguing double emission peaks from the core and shell, respectively. A highly non-concentric core@shell structure model was proposed to explain the origin of double emissions from monodisperse QDs. Their charge transfer behavior was investigated by monitoring photoluminescence (PL) intensity variation with the introduction of electron or hole scavengers. It was found that the PL quenching of the PbS core is more efficient than that of the CdS shell, suggesting more efficient charge transfer from the core to scavengers, although the opposite was expected. Further measurements of the PL lifetime followed by wave function calculations disclosed that the time scale is the critical factor explaining the more efficient charge transfer from the core than from the shell. The charge transfer behavior was also examined on a series of single-emission core@shell QDs with either different core sizes or different shell thicknesses and dominant factors were identified. Towards photovoltaic applications, these PbS@CdS QDs were attached onto multi-walled carbon nanotubes (MWCNTs) and their charge transfer behavior was compared with that in the PbS-QD/MWCNT system. Results demonstrate that although the CdS shell serves as an electron transfer barrier, the electrons excited in the PbS cores can still be transferred into the MWCNTs efficiently when the shell thickness is ~0.7 nm. Considering their higher stability, these core@shell QDs are very promising for the development of highly efficient QD-based photovoltaic devices. Electronic supplementary information (ESI) available: The PL and absorption spectra of PbS@CdS QDs in solution and in films with and without the combination of MWCNTs, Gaussian curve fit to the PL spectra of representative QD film samples, PL lifetime and charge transfer rate from QDs to electron or hole scavengers, radial distribution functions for 1s electron levels of the PbS@CdS core@shell QD with a different core size and constant shell thickness. See DOI: 10.1039/c3nr03691j

Zhao, Haiguang; Liang, Hongyan; Gonfa, Belete Atomsa; Chaker, Mohamed; Ozaki, Tsuneyuki; Tijssen, Peter; Vidal, François; Ma, Dongling

2013-12-01

298

Experimental study of single-phase pressure drop and heat transfer in a micro-fin tube  

SciTech Connect

The single-phase pressure drop and heat transfer in a micro-fin tube were measured using oil and water as the working fluids. The Prandtl number varied from 3.2 to 220 and the Reynolds number ranged from 2500 to 90,000. The results show that there is a critical Reynolds number, Re{sub cr}, for heat transfer enhancement. For Retransfer in the micro-fin tube is the same as that in a smooth tube, but for Reynolds numbers higher than Re{sub cr}, the heat transfer in the micro-fin tube is gradually enhanced compared with a smooth tube. It reaches more than twice that in a smooth tube for Reynolds numbers greater than 30,000 with water as the working fluid. The Nusselt number is proportional to Pr {sup 0.56} in the enhanced region and is proportional to Pr {sup 0.3} in the non-enhanced region. For the high Prandtl number working fluid (oil, 80< Pr <220), the critical Reynolds number for heat transfer enhancement is about 6000, while for the low Prandtl number working fluid (water, 3.2< Pr <5.8), the critical Reynolds number for heat transfer enhancement is about 10,000. The friction factors in the micro-fin tube are almost the same as for a smooth tube for Reynolds numbers below 10,000. For Reynolds numbers higher than 30,000, the friction factor is about 40-50% higher than for a smooth tube. (author)

Li, Xiao-Wei; Meng, Ji-An; Li, Zhi-Xin [School of Aerospace, Tsinghua University, Beijing 100084 (China)

2007-11-15

299

Density functional theory based calculations of the transfer integral in a redox-active single-molecule junction  

NASA Astrophysics Data System (ADS)

There are various quantum chemical approaches for an ab initio description of transfer integrals within the framework of Marcus theory in the context of electron transfer reactions. In our paper, we aim to calculate transfer integrals in redox-active single molecule junctions, where we focus on the coherent tunneling limit with the metal leads taking the position of donor and acceptor and the molecule acting as a transport mediating bridge. This setup allows us to derive a conductance, which can be directly compared with recent results from a nonequilibrium Green's function approach. Compared with purely molecular systems we face additional challenges due to the metallic nature of the leads, which rules out some of the common techniques, and due to their periodicity, which requires k-space integration. We present three different methods, all based on density functional theory, for calculating the transfer integral under these constraints, which we benchmark on molecular test systems from the relevant literature. We also discuss many-body effects and apply all three techniques to a junction with a Ruthenium complex in different oxidation states.

Kastlunger, Georg; Stadler, Robert

2014-03-01

300

Origin of the red sites and energy transfer rates in single MEH-PPV chains at low temperature.  

PubMed

Single poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) molecules dispersed in thin poly(methylmethacrylate) films have been investigated by fluorescence emission, excitation and time-resolved spectroscopy at 1.2 K. For the molecular weight studied (?200 kDa) a bimodal distribution of emission maxima is observed. Based on a comparison of the spectroscopic properties of blue and red sites and on polarisation-resolved measurements, we argue in agreement with recent quantum-chemical calculations that the red subpopulation most probably does not arise from interchromophoric excitation delocalisation but is to be attributed to longer chromophoric units originating from ordered regions of a polymer chain, where due to constraints on the chain conformation larger conjugation lengths can be realised. In excitation spectra within the red spectral region we can identify multiple chromophoric units, among them chromophores without correspondence in the emission spectrum-donors of the intramolecular energy transfer. Zero-phonon lines of donor chromophores proved to be significantly broadened, indicating fast excited-state population decay due to energy transfer. Thus, a distribution of energy transfer times within MEH-PPV chains could be determined from donor zero-phonon line widths, with an average value of 3.9 ps. Our study represents the first direct measurement of energy transfer times in conjugated polymers, parameters that are crucial for the performance of many technical applications based on this class of material. PMID:21472962

Feist, Florian A; Zickler, Martin F; Basché, Thomas

2011-06-01

301

Charge transfer reductive doping of single crystal TiO 2 anatase  

Microsoft Academic Search

Electrochemical reductive doping and oxidative de-doping was employed to modify anatase photoelectrochemical properties in situ. Spectroelectrochemical (Raman) and surface analysis (XPS, STM) revealed that changes in surface composition are responsible for variations in the course of both dark and photoassisted charge transfer processes including sub-bandgap photoeffects. The amount of charge passed during electrochemical reduction and oxidation of the electrode served

Hana Pelouchova; Pavel Janda; Jan Weber; Ladislav Kavan

2004-01-01

302

A Single Model for Mass Transfer and Growth for Biodegradation Rates in Activated Sludge  

Microsoft Academic Search

In the scope of environmental risk assessment for new and existing chemicals a generic model is developed to predict the possible concentration of pollutants after passage of sewage treatment plants. The model combines Monod kinetics with mass transfer rates through an imaginary boundary layer between mixed liquor and active biomass. For each specific substance a combined rate constant can be

J. Blok

2001-01-01

303

Evidence that Transcription Factor AP-2? Is Not Required for Oct4 Repression in Mouse Blastocysts  

PubMed Central

In mouse blastocysts segregation of the inner cell mass (ICM) and the trophectoderm (TE) is regulated by the mutually antagonistic effects of the transcription factors Oct4 and Cdx2 expressed in the ICM and TE, respectively. In contrast, in other species such as bovine and human, Oct4 is not restricted to the ICM and continues to be expressed in the Cdx2-positive TE. A recent comparative study of the bovine and mouse Oct4 promoters revealed that additional mechanisms might act in conjunction with Cdx2 to downregulate Oct4 expression in the mouse TE lineage. For instance, the mouse Oct4 distal enhancer contains an AP-2? (Tcfap2c) binding motif that is absent in the bovine and human Oct4 distal enhancer. Nonetheless, the functional relevance of Tcfap2c in Oct4 repression during mouse preimplantation development was not tested. To elucidate the role of Tcfap2c in Oct4 expression an RNA interference approach was utilized. Depletion of Tcfap2c triggered a decrease in Oct4 expression at the 8-cell and morula stage. Remarkably, at the blastocyst stage depletion of Tcfap2c and/or its family member Tcfap2a had no effect on Oct4 repression. To test whether Tcfap2c interacts with Oct4 to positively regulate Oct4 expression, chromatin immunoprecipitation and in situ co-immunoprecipitation analyses were performed. These experiments revealed Tcfap2c and Oct4 binding were enriched at the Oct4 distal enhancer in embryonic stem (ES) cells, but were rapidly lost during differentiation into trophoblast-like cells when Oct4 became repressed. Moreover, Tcfap2c and Oct4 interactions were detected at the morula stage, but were lost during blastocyst formation. In summary, these data demonstrate that Tcfap2c is not required for Oct4 silencing in mouse blastocysts, but may be necessary for the maintenance of Oct4 expression during the 8 cell-to-morula transition. These findings support the notion Cdx2 is the predominant negative regulator of Oct4 expression during blastocyst formation in mice.

Choi, Inchul; Carey, Timothy S.; Wilson, Catherine A.; Knott, Jason G.

2013-01-01

304

Single neutron transfer coupling effects on sub-barrier elastic scattering and near-barrier fusion of {sup 15}C  

SciTech Connect

To date, the possible effects of coupling to nucleon transfer reactions on the elastic scattering and fusion of weakly bound exotic nuclei have been largely neglected. The {sup 15}C nucleus presents a virtually unique opportunity to test these effects for an almost pure s{sub 1/2} single neutron halo nucleus. We present a series of coupled reaction channel calculations of the sub-barrier elastic scattering and single neutron transfer reactions, plus near-barrier excitation functions of the total fusion cross section for the {sup 12}C, {sup 13}C, and {sup 15}C+{sup 208}Pb systems. The method is validated against data for {sup 12}C and {sup 13}C+{sup 208}Pb. A large effect on the sub-barrier elastic scattering due to coupling to the ({sup 15}C,{sup 14}C) single neutron stripping reaction is found, ascribed to the 2s{sub 1/2} halo nature of the {sup 15}C ground state, in contrast to the two stable carbon isotopes. We also find a significant diminution of the above barrier total fusion cross section for {sup 15}C due to this coupling, again in contrast to the stable isotopes.

Keeley, N.; Alamanos, N. [CEA/DSM/DAPNIA/SPhN Saclay, F-91191 Gif-sur-Yvette Cedex (France)

2007-05-15

305

Troika of the Mouse Blastocyst: Lineage Segregation and Stem Cells  

PubMed Central

The initial period of mammalian embryonic development is primarily devoted to cell commitment to the pluri-potent lineage, as well as to the formation of extraembryonic tissues essential for embryo survival in utero. This phase of development is also characterized by extensive morphological transitions. Cells within the preimplantation embryo exhibit extraordinary cell plasticity and adaptation in response to experimental manipulation, highlighting the use of a regulative developmental strategy rather than a predetermined one resulting from the non-uniform distribution of maternal information in the cytoplasm. Consequently, early mammalian development represents a useful model to study how the three primary cell lineages; the epiblast, primitive endoderm (also referred to as the hypoblast) and trophoblast, emerge from a totipotent single cell, the zygote. In this review, we will discuss how the isolation and genetic manipulation of murine stem cells representing each of these three lineages has contributed to our understanding of the molecular basis of early developmental events.

Artus, Jerome; Hadjantonakis, Anna-Katerina

2012-01-01

306

Synthesis, Transfer, and Devices of Single and Few-Layer Graphene by Chemical Vapor Deposition  

Microsoft Academic Search

The advance of graphene-based nanoelectronics has been hampered due to the difficulty in producing single- or few-layer graphene over large areas. We report a simple, scalable, and cost-efficient method to prepare graphene using methane-based CVD on nickel films deposited over complete Si\\/SiO2 wafers. By using highly diluted methane, single- and few-layer graphene were obtained, as confirmed by micro-Raman spectroscopy. In

Lewis Gomez De Arco; Yi Zhang; Akshay Kumar; Chongwu Zhou

2009-01-01

307

Matched transfer characteristics of single units in a compound slit sense organ  

Microsoft Academic Search

The transfer characteristics of the lyriform slit sense organ HS8 on the leg tibia ofCupiennius salei Keys. (Fig. 1) were investigated by electrophysiological experiments. The organ is made up of 7 slits. It was stimulated by deflecting the metatarsus toward the fixed tibia. The responses of the constituent slits were recorded individually.1.The step responses of the 2nd to the 4th

Johannes Bohnenberger; Gruppe Sinnesphysiologie

1981-01-01

308

Charge transfer through single molecule contacts: How reliable are rate descriptions?  

PubMed

Background: The trend for the fabrication of electrical circuits with nanoscale dimensions has led to impressive progress in the field of molecular electronics in the last decade. However, a theoretical description of molecular contacts as the building blocks of future devices is challenging, as it has to combine the properties of Fermi liquids in the leads with charge and phonon degrees of freedom on the molecule. Outside of ab initio schemes for specific set-ups, generic models reveal the characteristics of transport processes. Particularly appealing are descriptions based on transfer rates successfully used in other contexts such as mesoscopic physics and intramolecular electron transfer. However, a detailed analysis of this scheme in comparison with numerically exact solutions is still elusive.Results: We show that a formulation in terms of transfer rates provides a quantitatively accurate description even in domains of parameter space where strictly it is expected to fail, e.g., at lower temperatures. Typically, intramolecular phonons are distributed according to a voltage driven steady state that can only roughly be captured by a thermal distribution with an effective elevated temperature (heating). An extension of a master equation for the charge-phonon complex, to effectively include the impact of off-diagonal elements of the reduced density matrix, provides very accurate solutions even for stronger electron-phonon coupling.Conclusion: Rate descriptions and master equations offer a versatile model to describe and understand charge transfer processes through molecular junctions. Such methods are computationally orders of magnitude less expensive than elaborate numerical simulations that, however, provide exact solutions as benchmarks. Adjustable parameters obtained, e.g., from ab initio calculations allow for the treatment of various realizations. Even though not as rigorously formulated as, e.g., nonequilibrium Green's function methods, they are conceptually simpler, more flexible for extensions, and from a practical point of view provide accurate results as long as strong quantum correlations do not modify the properties of the relevant subunits substantially. PMID:22003449

Kast, Denis; Kecke, L; Ankerhold, J

2011-01-01

309

Charge transfer through single molecule contacts: How reliable are rate descriptions?  

PubMed Central

Summary Background: The trend for the fabrication of electrical circuits with nanoscale dimensions has led to impressive progress in the field of molecular electronics in the last decade. However, a theoretical description of molecular contacts as the building blocks of future devices is challenging, as it has to combine the properties of Fermi liquids in the leads with charge and phonon degrees of freedom on the molecule. Outside of ab initio schemes for specific set-ups, generic models reveal the characteristics of transport processes. Particularly appealing are descriptions based on transfer rates successfully used in other contexts such as mesoscopic physics and intramolecular electron transfer. However, a detailed analysis of this scheme in comparison with numerically exact solutions is still elusive. Results: We show that a formulation in terms of transfer rates provides a quantitatively accurate description even in domains of parameter space where strictly it is expected to fail, e.g., at lower temperatures. Typically, intramolecular phonons are distributed according to a voltage driven steady state that can only roughly be captured by a thermal distribution with an effective elevated temperature (heating). An extension of a master equation for the charge–phonon complex, to effectively include the impact of off-diagonal elements of the reduced density matrix, provides very accurate solutions even for stronger electron–phonon coupling. Conclusion: Rate descriptions and master equations offer a versatile model to describe and understand charge transfer processes through molecular junctions. Such methods are computationally orders of magnitude less expensive than elaborate numerical simulations that, however, provide exact solutions as benchmarks. Adjustable parameters obtained, e.g., from ab initio calculations allow for the treatment of various realizations. Even though not as rigorously formulated as, e.g., nonequilibrium Green’s function methods, they are conceptually simpler, more flexible for extensions, and from a practical point of view provide accurate results as long as strong quantum correlations do not modify the properties of the relevant subunits substantially.

Kecke, L; Ankerhold, J

2011-01-01

310

Charge-transfer processes in single CdSe/ZnS quantum dots with p-type NiO nanoparticles.  

PubMed

Charge-transfer processes in single QDs with p-type NiO nanoparticles result in fluorescence intensity and lifetime quenching, suppression of blinking behavior and enhancement of the dot's survival time. PMID:20461266

Wu, Xiangyang; Yeow, Edwin K L

2010-06-28

311

Recent advances in the chemoselective reduction of functional groups mediated by samarium(II) iodide: a single electron transfer approach.  

PubMed

Recently, samarium(II) iodide reductants have emerged as powerful single electron donors for the highly chemoselective reduction of common functional groups. Complete control of the product formation can be achieved on the basis of a judicious choice of a Sm(II) complex/proton donor couple, even in the presence of extremely sensitive functionalities (iodides, aldehydes). In most cases, the reductions are governed by thermodynamic control of the first electron transfer, which opens up new prospects for unprecedented transformations via radical intermediates under mild regio-, chemo- and diastereoselective conditions that are fully orthogonal to hydrogenation or metal-hydride mediated processes. PMID:24013846

Szostak, Michal; Spain, Malcolm; Procter, David J

2013-12-01

312

Direct observation of resonant energy transfer between quantum dots of two different sizes in a single water droplet  

NASA Astrophysics Data System (ADS)

Water soluble CdTe nanocrystals (NCs) of two different sizes capped by thioglycolic acid were synthesized and were dispersed in pure water. We have observed that the emission color of CdTe NCs has been changed in a single droplet of water during the evaporation of the solvent. This is attributed to Förster resonance energy transfer between CdTe NCs, when their concentration becomes high enough to ensure close proximity. By combining our results of photoluminescence with quantitative analysis we conclude that the coupling between different sized CdTe NCs via long-range dipole-dipole interactions was enhanced in aqueous solution due to Brownian motion.

Xu, Ling; Xu, Jun; Ma, Zhongyuan; Li, Wei; Huang, Xinfan; Chen, Kunji

2006-07-01

313

Correlated blinking via time dependent energy transfer in single CdSe quantum dot-dye nanoassemblies  

NASA Astrophysics Data System (ADS)

Optical confocal spectroscopy on self-assembled single nanoassemblies from CdSe/ZnS quantum dots (QD) and perylene diimide dye molecules demonstrates efficient Förster resonance energy transfer (FRET). Intramolecular dynamics of the flexible dye molecule change the FRET efficiency in course of the detection period of several minutes. This can be followed by correlated observations of luminescence intensities and related spectral shifts of both constituents. Contrary to several experiments on similar assemblies, the FRET efficiencies are by almost one order of magnitude larger in the non-polar liquid solvent TEHOS as compared e.g. to toluene. Experimental and theoretically expected efficiencies are in close agreement with each other.

Gerlach, Frank; Täuber, Daniela; von Borczyskowski, Christian

2013-05-01

314

Elective single day 3 embryo transfer halves the twinning rate without decrease in the ongoing pregnancy rate of an IVF\\/ICSI programme  

Microsoft Academic Search

BACKGROUND: Data on the effect of elective single embryo transfer (eSET) on the total and multiple pregnancy rates of an IVF\\/ICSI programme are reported. METHODS AND RESULTS: A retrospective cohort analysis of eSET was carried out over a 4 year period. A total of 1559 cycles resulted in 1464 transfers; 299 transfers of one top quality embryo (20.4%) and 86

Jan Gerris; Diane De Neubourg; Katelijne Mangelschots; Eric Van Royen; Miet Vercruyssen; Jorge Barudy-Vasquez; Marion Valkenburg; Greet Ryckaert

315

Properties of Sizeable [n]Cycloparaphenylenes as Molecular Models of Single-Wall Carbon Nanotubes Elucidated by Raman Spectroscopy: Structural and Electron-Transfer Responses under Mechanical Stress.  

PubMed

[n]Cycloparaphenylenes behave as molecular templates of "perfectly chemically defined" single-wall carbon nanotubes. These [n]CPP molecules have electronic, mechanical, and chemical properties in size correspondence with their giant congeners. Under mechanical stress, they form charge-transfer salts, or complexes with fullerene, by one-electron concave-convex electron transfer. PMID:24838669

Alvarez, Miriam Peña; Burrezo, Paula Mayorga; Kertesz, Miklos; Iwamoto, Takahiro; Yamago, Shigeru; Xia, Jianlong; Jasti, Ramesh; Navarrete, Juan T López; Taravillo, Mercedes; Baonza, Valentín G; Casado, Juan

2014-07-01

316

Energy transfer at the single-molecule level: synthesis of a donor-acceptor dyad from perylene and terrylene diimides.  

PubMed

In 2004, we reported single-pair fluorescence resonance energy transfer (spFRET), based on a perylene diimide (PDI) and terrylene diimide (TDI) dyad (1) that was bridged by a rigid substituted para-terphenyl spacer. Since then, several further single-molecule-level investigations on this specific compound have been performed. Herein, we focus on the synthesis of this dyad and the different approaches that can be employed. An optimized reaction pathway was chosen, considering the solubilities, reactivities, and accessibilities of the building blocks for each individual reaction whilst still using established synthetic techniques, including imidization, Suzuki coupling, and cyclization reactions. The key differentiating consideration in this approach to the synthesis of dyad 1 is the introduction of functional groups in a nonsymmetrical manner onto either the perylene diimide or the terrylene diimide by using imidization reactions. Combined with well-defined purification conditions, this modified approach allows dyad 1 to be obtained in reasonable quantities in good yield. PMID:23780819

Kim, Ha Na; Puhl, Larissa; Nolde, Fabian; Li, Chen; Chen, Long; Basché, Thomas; Müllen, Klaus

2013-07-01

317

A simple approach for COnsumption and RElease (CORE) analysis of metabolic activity in single mammalian embryos.  

PubMed

Non-invasive assay of the consumption and release of metabolites by individual human embryos could allow selection at the cleavage stage of development and facilitate Single Embryo Transfer in clinical IVF but will require simple, high throughput, sensitive methods applicable to small volume samples. A rapid, simple, non-invasive method has therefore been devised using a standard fluorescence plate reader, and used to measure the consumption of pyruvate and glucose, and release of lactate by single bovine embryos at all stages of preimplantation development in culture; amino acid profiles have been determined using HPLC. Early embryos with an 'intermediate' level (6.14±0.27 pmol/embryo/h) of pyruvate uptake were associated with the highest rate (68.3%) of blastocyst development indicating that a mid "optimum" range of pyruvate consumption correlates with high viability in this bovine model. PMID:23967049

Guerif, Fabrice; McKeegan, Paul; Leese, Henry J; Sturmey, Roger G

2013-01-01

318

Effects of Trichostatin A on In vitro Development of Porcine Embryos Derived from Somatic Cell Nuclear Transfer  

PubMed Central

Many different approaches have been developed to improve the efficiency of animal cloning by somatic cell nuclear transfer (SCNT), one of which is to modify histone acetylation levels using histone deacetylase inhibitors (HDACi) such as trichostatin A (TSA). In the present study, we examined the effect of TSA on in vitro development of porcine embryos derived from SCNT. We found that TSA treatment (50 nM) for 24 h following oocyte activation improved blastocyst formation rates (to 22.0%) compared with 8.9% in the non-treatment group and total cell number of the blastocysts for determining embryo quality also increased significantly (88.9?114.4). Changes in histone acetylation levels as a result of TSA treatment were examined using indirect immunofluorescence and confocal microscopy scanning. Results showed that the histone acetylation level in TSA-treated embryos was higher than that in controls at both acetylated histone H3 lysine 9 (AcH3K9) and acetylated histone H4 lysine 12 (AcH4K12). Next, we compared the expression patterns of seven genes (OCT4, ID1; the pluripotent genes, H19, NNAT, PEG1; the imprinting genes, cytokeratin 8 and 18; the trophoblast marker genes). The SCNT blastocysts both with and without TSA treatment showed lower levels of OCT4, ID1, cytokeratin 8 and 18 than those of the in vivo blastocysts. In the case of the imprinting genes H19 and NNAT, except PEG1, the SCNT blastocysts both with and without TSA treatment showed higher levels than those of the in vivo blastocysts. Although the gene expression patterns between cloned blastocysts and their in vivo counterparts were different regardless of TSA treatment, it appears that several genes in NT blastocysts after TSA treatment showed a slight tendency toward expression patterns of in vivo blastocysts. Our results suggest that TSA treatment may improve preimplantation porcine embryo development following SCNT.

Jeong, Yeon Ik; Park, Chi Hun; Kim, Huen Suk; Jeong, Yeon Woo; Lee, Jong Yun; Park, Sun Woo; Lee, Se Yeong; Hyun, Sang Hwan; Kim, Yeun Wook; Shin, Taeyoung; Hwang, Woo Suk

2013-01-01

319

Investigating trends in proton single-particle states in Z = 51 isotopes using transfer reactions  

NASA Astrophysics Data System (ADS)

A study of low-lying excited states in Z = 51 isotopes has been performed using single-proton adding reactions, (?,t) and (3He,d), on the series of stable, even mass Z = 50 isotopes. Our goal was to build upon results from a previous (?,t) study [1] by examining the fragmentation of high-j (g7/2 and h11/2) single-proton strengths utilising greater statistics. Data from the (3He,d) measurements provide further information regarding the low-j orbitals within this nuclear shell. Preliminary findings from the analysis are presented in this report.

Mitchell, A. J.; Freeman, S. J.; Schiffer, J. P.; Clark, J. A.; Deibel, C. M.; Hoffman, C. R.; Howard, A. M.; Kay, B. P.; Parker, P. D.; Sharp, D. K.; Thomas, J. S.

2012-09-01

320

Studies of Nuclei Close to 132Sn Using Single-Neutron Transfer Reactions  

SciTech Connect

Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of 132Sn, 130Sn, and 134Te and deuterated polyethylene targets. Preliminary results are presented. The Q-value spectra for 133Sn, 131Sn and 135Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf7/2 nature of the ground state of 133Sn, and 2p3/2 for the 3.4 MeV state in 131Sn.

Jones, K. L. [University of Tennessee, Knoxville (UTK); Pain, S. D. [Rutgers University; Kozub, R. L. [Tennessee Technological University; Adekola, Aderemi S [ORNL; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Catford, Wilton N [ORNL; Chae, K. Y. [University of Tennessee, Knoxville (UTK); Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Erikson, Luke [Colorado School of Mines, Golden; Gaddis, A. L. [Furman University; Greife, U. [Colorado School of Mines, Golden; Grzywacz, R. K. [University of Tennessee, Knoxville (UTK); Harlin, Christopher W [ORNL; Hatarik, Robert [Rutgers University; Howard, Joshua A [ORNL; James, J. [Colorado School of Mines, Golden; Kapler, R. [University of Tennessee, Knoxville (UTK); Krolas, W. [University of Warsaw; Liang, J Felix [ORNL; Ma, Zhanwen [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Patterson, N. P. [University of Surrey, UK; Paulauskas, Stanley [University of Tennessee, Knoxville (UTK); Shapira, Dan [ORNL; ShrinerJr., J. F. [Tennessee Technological University; Sikora, M. [Rutgers University; Sissom, D. J. [Tennessee Technological University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK; Thomas, J. S. [Rutgers University; Wilson, Gemma L [ORNL

2009-01-01

321

Probing Single-Neutron Levels in 127,129Sn via Transfer Reactions  

NASA Astrophysics Data System (ADS)

The (d,p) reaction was measured with radioactive ion beams of 126Sn and 128Sn (~5 MeV/u) in inverse kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory, utilizing the SuperORRUBA silicon detector array. Angular distributions of reaction protons were measured for several states in 127Sn and 129Sn in order to determine angular momentum transfers and deduce spectroscopic factors. Combined with previous experiments on 130Sn and 132Sn, these results provide a complete set of (d,p) reaction data on even tin isotopes between stable 124Sn and doubly magic 132Sn.

Manning, B.; Cizewski, J. A.; Howard, M. E.; O'Malley, P. D.; Ratkiewicz, A.; Kozub, R. L.; Ahn, S.; Jones, K. L.; Pittman, S. T.; Allmond, J. M.; Bardayan, D. W.; Beene, J. R.; Galindo-Uribarri, A.; Liang, J. F.; Nesaraja, C. D.; Pain, S. D.; Radford, D. C.; Schmitt, K. T.; Shapira, D.; Smith, M. S.; Chae, K. Y.; Chipps, K. A.; Matos, M.; Padilla-Rodal, E.; Peters, W. A.

2014-09-01

322

Quantitative description of the lie-to-sit-to-stand-to-walk transfer by a single body-fixed sensor.  

PubMed

Sufficient capacity and quality of performance of complex movement patterns during daily activity, such as standing up from a bed, is a prerequisite for independent living and also may be an indicator of fall risk. Until now, the transfer from lying-to-sit-to-stand-to-walk (LSSW) was investigated by functional testing, subjective rating or for activity classification of subtasks. The aim of this study was to use a single body-fixed inertial sensor to describe the complex movement of the LSSW transfer. Fifteen older patients of a geriatric rehabilitation clinic (median age 81 years) and ten young, healthy persons (median age 37 years) were instructed to stand up from bed in a continuous movement and to start walking. Data acquisition was performed using an inertial measurement unit worn on the lower back. Parameters extracted from the sensor outputs were able to correctly classify the subjects into a correct group with sensitivity and specificity between 90% and 100%. ICCs 3,1 of the descriptive parameters ranged between 0.85 and 0.95 in the cohort of older patients. The different strategies adopted to transfer from lying to standing up were estimated through an extended Kalman filter. The results obtained in this study suggest the usability of the instrumented LSSW test in clinical settings. PMID:23221832

Bagalà, Fabio; Klenk, Jochen; Cappello, Angelo; Chiari, Lorenzo; Becker, Clemens; Lindemann, Ulrich

2013-07-01

323

Serial transfer of single-cell-derived immunocompetence reveals stemness of CD8(+) central memory T cells.  

PubMed

Maintenance of immunological memory has been proposed to rely on stem-cell-like lymphocytes. However, data supporting this hypothesis are focused on the developmental potential of lymphocyte populations and are thus insufficient to establish the functional hallmarks of stemness. Here, we investigated self-renewal capacity and multipotency of individual memory lymphocytes by in vivo fate mapping of CD8(+) T cells and their descendants across three generations of serial single-cell adoptive transfer and infection-driven re-expansion. We found that immune responses derived from single naive T (Tn) cells, single primary, and single secondary central memory T (Tcm) cells reached similar size and phenotypic diversity, were subjected to comparable stochastic variation, and could ultimately reconstitute immunocompetence against an otherwise lethal infection with the bacterial pathogen Listeria monocytogenes. These observations establish that adult tissue stem cells reside within the CD62L(+) Tcm cell compartment and highlight the promising therapeutic potential of this immune cell subset. PMID:25035956

Graef, Patricia; Buchholz, Veit R; Stemberger, Christian; Flossdorf, Michael; Henkel, Lynette; Schiemann, Matthias; Drexler, Ingo; Höfer, Thomas; Riddell, Stanley R; Busch, Dirk H

2014-07-17

324

Automated Hydrogen/Deuterium Exchange Electron Transfer Dissociation High Resolution Mass Spectrometry Measured at Single-Amide Resolution  

NASA Astrophysics Data System (ADS)

Hydrogen deuterium exchange mass spectrometry (HDX-MS) is a well established method for the measurement of solution-phase deuterium incorporation into proteins, which can provide insight into protein conformational mobility. However, most HDX measurements are constrained to regions of the protein where pepsin proteolysis allows detection at peptide resolution. Recently, single-amide resolution deuterium incorporation has been achieved by limiting gas-phase scrambling in the mass spectrometer. This was accomplished by employing a combination of soft ionization and desolvation conditions coupled with the radical-driven fragmentation technique electron transfer dissociation (ETD). Here, a hybrid LTQ-Orbitrap XL is systematically evaluated for its utility in providing single-amide deuterium incorporation for differential HDX analysis of a nuclear receptor upon binding small molecule ligands. We are able to show that instrumental parameters can be optimized to minimize scrambling and can be incorporated into an established and fully automated HDX platform making differential single-amide HDX possible for bottom-up analysis of complex systems. We have applied this system to determine differential single amide resolution HDX data for the peroxizome proliferator activated receptor bound with two ligands of interest.

Landgraf, Rachelle R.; Chalmers, Michael J.; Griffin, Patrick R.

2012-02-01

325

A charge transfer single crystal field effect transistor operating at low voltages.  

PubMed

An organic FET employing a single crystal of a donor-acceptor system based on coronene tetracarboxylate and a methyl viologen derivative exhibited an impressive mobility of 0.53 cm(2) V(-1) s(-1), operating under 2 V in the ambient atmosphere. Quantum mechanical calculations have provided an insight into the hole-dominant transport in the crystal. PMID:23703241

Sagade, Abhay A; Rao, K Venkata; George, Subi J; Datta, Ayan; Kulkarni, Giridhar U

2013-07-01

326

Low-pressure airlift fermenter for single cell protein production. I. Design and oxygen transfer studies  

Microsoft Academic Search

The energy consumption of a fermenter constitutes a major part of the operating expense of a single cell protein process. A low-pressure airlift fermenter was designed to reduce this cost. In this new design, the fermenter broth is kept below 120 cm in depth, and air alone is employed to fulfil the need of supplying oxygen, and cooling and agitating

N. Y. Chen; E. F. Kondis; S. Srinivasan

1987-01-01

327

Unraveling electronic energy transfer in single conjugated polyelectrolytes encapsulated in lipid vesicles  

PubMed Central

A method for the study of conjugated polyelectrolyte (CPE) photophysics in solution at the single-molecule level is described. Extended observation times of single polymer molecules are enabled by the encapsulation of the CPEs within 200-nm lipid vesicles, which are in turn immobilized on a surface. When combined with a molecular-level visualization of vesicles and CPE via cryo-transmission electron microscopy, these single-molecule spectroscopy studies on CPEs enable us to directly correlate the polymer conformation with its spectroscopic features. These studies are conducted with poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylene-vinylene] (MPS-PPV, a negatively charged CPE), when encapsulated in neutral and in negatively charged lipid vesicles. MPS-PPV exists as a freely diffusing polymer when confined in negatively charged vesicles. Individual MPS-PPV molecules adopt a collapsed-chain conformation leading to efficient energy migration over multiple chromophores. Both the presence of stepwise photobleaching in fluorescence intensity-time trajectories and emission from low-energy chromophores along the chain are observed. These results correlate with the amplified sensing potential reported for MPS-PPV in aqueous solution. When confined within neutral vesicles, single MPS-PPV molecules adopt an extended conformation upon insertion in the lipid bilayer. In this case emission arises from multiple chromophores within the isolated polymer chains, leading to an exponential decay of the intensity over time and a broad blue-shifted emission spectrum.

Karam, Pierre; Ngo, An Thien; Rouiller, Isabelle; Cosa, Gonzalo

2010-01-01

328

On-demand single-electron transfer between distant quantum dots  

Microsoft Academic Search

Single-electron circuits of the future, consisting of a network of quantum dots, will require a mechanism to transport electrons from one functional part of the circuit to another. For example, in a quantum computer decoherence and circuit complexity can be reduced by separating quantum bit (qubit) manipulation from measurement and by providing a means of transporting electrons between the corresponding

R. P. G. McNeil; M. Kataoka; C. J. B. Ford; C. H. W. Barnes; D. Anderson; G. A. C. Jones; I. Farrer; D. A. Ritchie

2011-01-01

329

Experimental Investigation of the Discharge Coefficient and Impingement Heat Transfer Characteristics of a Single Jet in Cross Flow  

NASA Astrophysics Data System (ADS)

This experimentation investigates the local heat transfer characteristics of an impinging jet with the effects of cross flow. The jet is formed by a single round hole with a diameter of 0.25 inches, sharp edges and a length to diameter ratio of 4. For one combination of impingement plate spacing and cross flow to jet flow mass velocity ratio, detailed photographs of a sheet of liquid crystal were taken. These photographs were then used to create a Nusselt number contour plot. Observations are made regarding the comparison of the Nusselt number contour plots with and without cross flow. Comparisons are also made to data in open literature citing the degradation of the average Nusselt number with cross flow to that without cross flow. While the main focus of this study was the heat transfer of an impinging jet, a large amount of discharge coefficient data was also gathered for a single, sharp edged, round hole in the presence of cross flow. It compared very well to other investigator's data and a correlation relating the discharge coefficient to the mass velocity ratio is reported.

Roberts, Brian

330

Synthesis and transfer of single-layer transition metal disulfides on diverse surfaces.  

PubMed

Recently, monolayers of layered transition metal dichalcogenides (LTMD), such as MX2 (M = Mo, W and X = S, Se), have been reported to exhibit significant spin-valley coupling and optoelectronic performances because of the unique structural symmetry and band structures. Monolayers in this class of materials offered a burgeoning field in fundamental physics, energy harvesting, electronics, and optoelectronics. However, most studies to date are hindered by great challenges on the synthesis and transfer of high-quality LTMD monolayers. Hence, a feasible synthetic process to overcome the challenges is essential. Here, we demonstrate the growth of high-quality MS2 (M = Mo, W) monolayers using ambient-pressure chemical vapor deposition (APCVD) with the seeding of perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS). The growth of a MS2 monolayer is achieved on various surfaces with a significant flexibility to surface corrugation. Electronic transport and optical performances of the as-grown MS2 monolayers are comparable to those of exfoliated MS2 monolayers. We also demonstrate a robust technique in transferring the MS2 monolayer samples to diverse surfaces, which may stimulate the progress on the class of materials and open a new route toward the synthesis of various novel hybrid structures with LTMD monolayer and functional materials. PMID:23506011

Lee, Yi-Hsien; Yu, Lili; Wang, Han; Fang, Wenjing; Ling, Xi; Shi, Yumeng; Lin, Cheng-Te; Huang, Jing-Kai; Chang, Mu-Tung; Chang, Chia-Seng; Dresselhaus, Mildred; Palacios, Tomas; Li, Lain-Jong; Kong, Jing

2013-04-10

331

Ectopic pregnancy rates with day 3 versus day 5 embryo transfer: a retrospective analysis  

Microsoft Academic Search

BACKGROUND: Blastocyst transfer may theoretically decrease the incidence of ectopic pregnancy following IVF-ET in view of the decreased uterine contractility reported on day 5. The purpose of our study is to specifically compare the tubal pregnancy rates between day 3 and day 5 transfers. METHODS: A retrospective analysis of all clinical pregnancies conceived in our IVF program since 1998 was

Amin A Milki; Sunny H Jun

2003-01-01

332

Interspecies Somatic Cell Nuclear Transfer Is Dependent on Compatible Mitochondrial DNA and Reprogramming Factors  

Microsoft Academic Search

Interspecies somatic cell nuclear transfer (iSCNT) involves the transfer of a nucleus or cell from one species into the cytoplasm of an enucleated oocyte from another. Once activated, reconstructed oocytes can be cultured in vitro to blastocyst, the final stage of preimplantation development. However, they often arrest during the early stages of preimplantation development; fail to reprogramme the somatic nucleus;

Yan Jiang; Richard Kelly; Amy Peters; Helena Fulka; Adam Dickinson; Daniel A. Mitchell; Justin C. St. John; Joanna Mary Bridger

2011-01-01

333

Accumulation of advanced glycation end products in the rabbit blastocyst under maternal diabetes.  

PubMed

Diabetes mellitus (DM) during pregnancy is one of the leading causes of perinatal morbidity and birth defects. The mechanism by which maternal hyperglycemia, the major teratogenic factor, induces embryonic malformations remains unclear. Advanced glycation end products (AGEs) are known to accumulate during the course of DM and contribute to the development of diabetic complications. Employing a diabetic rabbit model, we investigated the influence of maternal hyperglycemia during the preimplantation period on AGE formation (pentosidine, argpyrimidine, and N(?)-carboxymethyllysine (CML)) in the reproductive tract and the embryo itself. As a consequence of type 1 DM, the AGE levels in blood plasma increased up to 50%, correlating closely with an AGE accumulation in the endometrium of diabetic females. Embryos from diabetic mothers had increased protein-bound CML levels and showed enhanced fluorescent signals for AGE-specific fluorescence in the blastocyst cavity fluid (BCF). The quantification of CML by HPLC-mass spectrometry (MS/MS) showed a higher amount of soluble CML in the BCF of blastocysts from diabetic rabbits (0.26±0.05??mol/l) compared with controls (0.18±0.02??mol/l). The high amount of AGEs in blastocysts from diabetic mothers correlates positively with an increased AGER (receptor for AGE (RAGE)) mRNA expression. Our study gives alarming insights into the consequences of poorly controlled maternal diabetes for AGE formation in the embryo. Maternal hyperglycemia during the preimplantation period is correlated with an increase in AGE formation in the uterine environment and the embryo itself. This may influence the development of the embryo through increased AGE-mediated cellular stress by RAGEs. PMID:24821834

Haucke, Elisa; Navarrete Santos, Alexander; Simm, Andreas; Henning, Christian; Glomb, Marcus A; Gürke, Jacqueline; Schindler, Maria; Fischer, Bernd; Navarrete Santos, Anne

2014-08-01

334

Importance of Thomas single-electron transfer in fast p-He collisions  

SciTech Connect

We report experimental angular differential cross sections for nonradiative single-electron capture in p-He collisions (p+ He -> H + He{sup +}) with a separate peak at the 0.47 mrad Thomas scattering angle for energies in the 1.3-12.5 MeV range. We find that the intensity of this peak scales with the projectile velocity as v{sub P}{sup -11}. This constitutes the first experimental test of the prediction from 1927 by L. H. Thomas [Proc. R. Soc. 114, 561 (1927)]. At our highest energy, the peak at the Thomas angle contributes with 13.5% to the total integrated nonradiative single-electron capture cross section.

Fischer, D. [Department of Physics, Stockholm University, S-10691 Stockholm (Sweden); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1 D-69126 (Germany); Gudmundsson, M.; Berenyi, Z.; Haag, N.; Johansson, H. A. B.; Misra, D.; Reinhed, P.; Cederquist, H. [Department of Physics, Stockholm University, S-10691 Stockholm (Sweden); Kaellberg, A.; Simonsson, A.; Schmidt, H. T. [Manne Siegbahn Laboratory, Stockholm University, S-11418 Stockholm (Sweden); Stoechkel, K. [Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

2010-01-15

335

Impact of transient single-phase heat transfer modeling on predicted BWR fuel stability margins  

Microsoft Academic Search

Boiling flow instabilities must be considered in the design and analysis of many devices in energy production, e.g., boiling water nuclear reactors (BWRs). The most common thermal-hydraulic instability mechanism of interest to BWR operation in known as density-wave oscillations. An important aspect of analytically investigating density-wave oscillations deals with heater wall dynamic modeling in the single- and two-phase regions, respectively.

R. P. Taleyarkhan; A. F. McFarlane; M. Z. Podowski; R. T. Jr. Lahey

1987-01-01

336

Detection of electron transfer between single monolayers by a Maxwell-displacement-current measuring technique  

Microsoft Academic Search

Electron transport between adjacent single monolayers in a two-monolayer system was first detected in the absence of an external electric field by the displacement-current measuring technique. We fabricated junctions incorporating a two-layer system, i.e., a monolayer of sensitizer (S) and a monolayer of electron acceptor (A), and an air gap. We then examined the displacement-current generation in the two-layer system

Mitsumasa Iwamoto; Yutaka Majima; Makoto Atsuzawa; Masaaki Kakimoto; Yoshio Imai

1992-01-01

337

Effect of the Pr3+ ? Gd3+ energy transfer in multicomponent garnet single crystal scintillators  

NASA Astrophysics Data System (ADS)

Luminescence processes in the undoped and Pr3+-doped (Gd,RE)3(Ga,Al)5O12, RE = Lu,Y, multicomponent garnets are studied by time-resolved photoluminescence spectroscopy. Energy transfer processes between Pr3+ and Gd3+ causing significant deterioration of the scintillation performance are considered in detail. As is shown in current work, an overlap of the 5d1-3H4 emission transition of Pr3+ and 8S-6Px absorption transition of Gd3+ results in unwanted depletion of Pr3+ 5d1 excited state and is further intensified by the concentration quenching in the Gd3+-sublattice. This process explains a drastic decrease of light yield in Pr3+-doped Gd3+-containing multicomponent garnets observed in a previous work.

Babin, V.; Nikl, M.; Kamada, K.; Beitlerova, A.; Yoshikawa, A.

2013-09-01

338

Electron Transfer between Cytochrome C and Cytochome C Peroxidase in Single Crystals  

SciTech Connect

Cytochrome c (Cc) and cytochrome c peroxidase (CcP) form an important redox pair for understanding interprotein electron transfer (ET). Measurements of ET rates from photoexcited CcP substituted with Zn porphyrin to either yeast Fe(III)Cc or horse Fe(III)Cc in crystals reveal that the molecular associations found in the respective crystal structures determine solution reactivity. Similar forward rates for yeast isozyme-1 Cc (yCc) and yCc homologue horse Cc (hCc), despite different orientations relative to CcP, suggest small-amplitude conformational gating of ET even in the crystalline state; faster back ET in the yCc compared to the hCc complex agrees with the relative coupling between redox sites predicted by the structures.

Kang, Seong A.; Marjavaara, Pieti J.; Crane, Brian R. (Cornell)

2010-11-10

339

Influence of a prostaglandin synthesis inhibitor administered at embryo transfer on pregnancy rates of recipient cows.  

PubMed

Elevated uterine luminal concentrations of prostaglandin F(2alpha) (PGF(2alpha)) have been negatively associated with embryo quality and pregnancy rates. Two studies were performed in cows to determine PGF(2alpha) release from uterine endometrium following embryo transfer and to investigate administration of flunixin meglumine (FM), a prostaglandin synthesis inhibitor, on pregnancy rates following embryo transfer. In Experiment 1, blood samples were collected prior to and after embryo transfer from the posterior vena cava via saphenous vein cannulation. Serum profiles of PGF(2alpha) indicated that manipulation of the reproductive tract during embryo transfer was followed by increased release of PGF(2alpha) from the uterine endometrium. In Experiment 2, estrus (day=0) was synchronized in recipient animals and a single embryo transferred 7 days after estrus. At the time of non-surgical embryo transfer, animals were randomly assigned to receive either FM (FM; n=1300) or remain untreated (control (CON); n=797). Data collected at transfer included stage of embryo development, embryo quality, technician, and transfer quality score. Overall pregnancy rates of cows receiving FM (65%) were higher than control cows (60%; P<0.02). Pregnancy rates following transfer of quality 1 (good) embryos did not differ (P>0.05) between treatments. However, pregnancy rates of quality 2 (fair) embryos were higher in animals receiving FM than in CON (P<0.01). Moreover, pregnancy rates of transferred morula- and blastocyst-stage embryos were higher in FM-treated than in controls (P<0.06 and P<0.04, respectively). In conclusion, uterine release of PGF(2alpha) is elevated following embryo transfer and administration of a PGF(2alpha) synthesis inhibitor at the time of embryo transfer improved pregnancy rates in cows. PMID:16303603

Scenna, F N; Hockett, M E; Towns, T M; Saxton, A M; Rohrbach, N R; Wehrman, M E; Schrick, F N

2005-12-01

340

A distribution-based method to resolve single-molecule F?rster resonance energy transfer observations  

PubMed Central

We introduce a new approach to analyze single-molecule Förster resonance energy transfer (FRET) data. The method recognizes that FRET efficiencies assumed by traditional ensemble methods are unobservable for single molecules. We propose instead a method to predict distributions of FRET parameters obtained directly from the data. Distributions of FRET rates, given the data, are precisely defined using Bayesian methods and increase the information derived from the data. Benchmark comparisons find that the response time of the new method outperforms traditional methods of averaging. Our approach makes no assumption about the number or distribution of underlying FRET states. The new method also yields information about joint parameter distributions going beyond the standard framework of FRET analysis. For example, the running distribution of FRET means contains more information than any conceivable single measure of FRET efficiency. The method is tested against simulated data and then applied to a pilot-study sample of calmodulin molecules immobilized in lipid vesicles, revealing evidence for multiple dynamical states.

Backovic, Mihailo; Price, E. Shane; Johnson, Carey K.; Ralston, John P.

2011-01-01

341

Electron transfer through a single barrier inside a molecule: From strong to weak coupling  

NASA Astrophysics Data System (ADS)

In all theoretical treatments of electron transport through single molecules between two metal electrodes, a clear distinction has to be made between a coherent transport regime with a strong coupling throughout the junction and a Coulomb blockade regime in which the molecule is only weakly coupled to both leads. The former case where the tunnelling barrier is considered to be delocalized across the system can be well described with common mean-field techniques based on density functional theory (DFT), while the latter case with its two distinct barriers localized at the interfaces usually requires a multideterminant description. There is a third scenario with just one barrier localized inside the molecule, which we investigate here using a variety of quantum-chemical methods by studying partial charge shifts in biphenyl radical ions induced by an electric field at different angles to modulate the coupling and thereby the barrier within the ?-system. We find steps rounded off at the edges in the charge versus field curves for weak and intermediate coupling, whose accurate description requires a correct treatment of both exchange and dynamical correlation effects is essential. We establish that DFT standard functionals fail to reproduce this feature, while a long range corrected hybrid functional fares much better, which makes it a reasonable choice for a proper DFT-based transport description of such single barrier systems.

Stadler, Robert; Cornil, Jérôme; Geskin, Victor

2012-08-01

342

Flexor hallux tendon transfer: comparative study through double or single approach  

PubMed Central

OBJECTIVE: To quantify the FHL length difference obtained through a single approach and by a double combined approach. METHODS: 16 fresh cadavers, a total of 32 feet, were used to measure the FHL graft length. With the cadaver positioned in ventral decubitus, a posteromedial incision in the ankle and a second incision in the plantar cavus were performed. RESULTS: The average gain of tendon's length (GTL) was of 42.43 mm, the lowest value being 32 mm and the largest 48 mm. The comparative analysis of the GTL on the right and left sides through the paired "t" Test does not show statistical differences, with a p-value = 0.463 and a statistical power of 0.1443. The height analysis of the sample and the right and left GTL performed through linear regression do not show statistically significant differences, with a p-value of 0.38311 and 0.82640, respectively. CONCLUSION: Harvesting the FHL graft using a double combined approach yields a 42.43 mm length gain in comparison to harvesting using the single approach. Level of Evidence III, Case Control Study.

Sakaki, Marcos Hideyo; Godoy-Santos, Alexandre Leme; Ortiz, Rafael Trevisan; Araujo, Antonio; Fernandes, Tulio Diniz

2014-01-01

343

Direct comparison of the effects of slow freezing and vitrification on late blastocyst gene expression, development, implantation and offspring of rabbit morulae.  

PubMed

This study aimed to assess the effect of different cryopreservation procedures (slow freezing vs vitrification) on the gene expression in pre-implantation embryos and its implication in post-implantation embryo losses in rabbit. For this purpose, rabbit morulae were recovered at Day 3 of development, frozen or vitrified and transferred to recipients. Then, embryos were recovered on Day 3 post-transfer (Day 6 of development) or kept until the end of gestation. Apart from the gene expression analysis at Day 6, we also studied the pre-implantatory and foetal development ability of both cryopreserved embryo types by evaluating late blastocyst development at Day 6, embryo implantation at Day 11 post-transfer (Day 14 of development) and birth rate. We reported that slow freezing and vitrification have similar effects on embryo developmental ability till Day 6, but the distribution of losses changes during implantation and further development. These similarities at Day 6 of development were also reflected in gene expression patterns, and transcriptome analysis showed no differences between frozen and vitrified embryos. Our results confirm that vitrification provides better implantation and birth rates than slow freezing for rabbit embryos. As both the techniques are commonly used in human assisted reproduction, further experiments must be conducted to clarify the causes that may hinder foetal development and their impact on adulthood. PMID:24750498

Saenz-de-Juano, M D; Marco-Jimenez, F; Viudes-de-Castro, M P; Lavara, R; Vicente, J S

2014-06-01

344

Monozygotic twins with discordant karyotypes following preimplantation genetic screening and single embryo transfer: case report  

PubMed Central

Purpose To report a case of monozygotic monochorial diamniotic twins with discordant karyotypes. Methods and results The pregnancy was achieved following a treatment cycle with intracytoplasmic sperm injection (ICSI) and preimplantation genetic screening (PGS) for chromosomes X, Y, 13, 16, 18, 21, 22. One embryo euploid for studied chromosomes was transferred. Prenatal ultrasonography revealed monozygotic twins. One fetus had growth retardation, multiple organ abnormalities and polyhydramnion. The other twin had normal ultrasound appearance. Delivery on week 29 of gestation resulted in the birth of two females, a stillborn twin with karyotype 45,XX,-13[12]/46,XX,r(13)[3] and a healthy twin with normal karyotype. Conclusions The discordance in the twins’ karyotypes originated from a mosaic embryo. Structural chromosomal abnormality of the affected twin could not be revealed using standard PGS investigation. Embryo splitting occurred probably due to apoptotic process in an early stage of embryo development. Apoptosis represents one of the possible mechanisms which can explain the embryo twinning process globally.

Gaillyova, Renata; Travnik, Pavel; Oracova, Eva; Vesela, Katerina; Hromadova, Lenka; Vesely, Jan; Musilova, Petra; Rubes, Jiri; Kadlecova, Jitka; Slamova, Iva; Makaturova, Eva; Vranova, Vladimira

2010-01-01

345

Effect of Culture System on Developmental Competence, Cryosurvival and DNA-Fragmentation of In Vitro Bovine Blastocysts  

PubMed Central

Background This study investigated the effect of two in vitro embryo culture systems (co-culture system versus cell-free sequential-media) on developmental competence, cryosurvival and DNA- fragmentation of in vitro developed bovine blastocysts. Materials and Methods Bovine presumptive zygotes were cultured in Ménézo's B2 (B2) plus vero-cells or sequential synthetic oviductal fluid (SOF) for eight days. Subsequently, half of the expanded blastocysts developed in both groups were vitrified, warmed within 30 minutes and post- warming embryos along with their corresponding non-vitrified embryos were cultured for two additional days in the same medium used before vitrification. Embryo development, cryosurvival and apoptosis were compared between the groups. Results For non-vitrified embryos, culture in SOF significantly promoted the potency of embryos to develop into blastocysts compared with the co-culture system. The difference in post vitrification survival rate of SOF blastocysts (83.3%) was insignificant compared with co-culture (84.3%). However, while total cell number of warmed blastocysts in the co-culture system was significantly higher in the co-culture versus the sequential system (215.4 vs. 170.4), the quality of survived embryos in terms of hatching ability and apoptosis was adversely affected by co-culture compared with SOF (65.0% vs. 74.3%, and 13.5% vs. 10.0%, respectively; p<0.05). Conclusion Although co-culture system may increase the viability of embryos following cryopreservation, the potency and dynamics of blastocyst formation significantly increased with sequential media compared to the co-culture system which can compensate for the lower efficiency of sequential media for vitrification/warming purposes.

Hajian, Mahdi; Hosseini, Seyed Morteza; Asgari, Vajiheh; Ostadhoosseini, Somayyeh; Forouzanfar, Mohsen; Nasr Esfahani, Mohammad Hossein

2011-01-01

346

A simplified one-step nuclear transfer procedure alters the gene expression patterns and developmental potential of cloned porcine embryos  

PubMed Central

Various somatic cell nuclear transfer (SCNT) techniques for mammalian species have been developed to adjust species-specific procedures to oocyte-associated differences among species. Species-specific SCNT protocols may result in different expression levels of developmentally important genes that may affect embryonic development and pregnancy. In the present study, porcine oocytes were treated with demecolcine that facilitated enucleation with protruding genetic material. Enucleation and donor cell injection were performed either simultaneously with a single pipette (simplified one-step SCNT; SONT) or separately with different pipettes (conventional two-step SCNT; CTNT) as the control procedure. After blastocysts from both groups were cultured in vitro, the expression levels of developmentally important genes (OCT4, NANOG, EOMES, CDX2, GLUT-1, PolyA, and HSP70) were analyzed by real-time quantitative polymerase chain reaction. Both the developmental rate according to blastocyst stage as well as the expression levels CDX2, EOMES, and HSP70 were elevated with SONT compared to CTNT. The genes with elevated expression are known to influence trophectoderm formation and heat stress-induced arrest. These results showed that our SONT technique improved the development of SCNT porcine embryos, and increased the expression of genes that are important for placental formation and stress-induced arrest.

Park, Sang Kyu

2014-01-01

347

78 FR 41070 - Notice of Single-Case Deviation from Competition Requirements: Transfer of Grantee Request for...  

Federal Register 2010, 2011, 2012, 2013

...Competition Requirements: Transfer of Grantee Request for the Detroit Healthy Start...Competition Requirements: Transfer of Grantee Request for the Detroit Healthy Start...SUMMARY: HRSA will be issuing a grantee transfer without competition for the...

2013-07-09

348

Transcriptome Profiling of Rabbit Parthenogenetic Blastocysts Developed under In Vivo Conditions  

PubMed Central

Parthenogenetic embryos are one attractive alternative as a source of embryonic stem cells, although many aspects related to the biology of parthenogenetic embryos and parthenogenetically derived cell lines still need to be elucidated. The present work was conducted to investigate the gene expression profile of rabbit parthenote embryos cultured under in vivo conditions using microarray analysis. Transcriptomic profiles indicate 2541 differentially expressed genes between parthenotes and normal in vivo fertilised blastocysts, of which 76 genes were upregulated and 16 genes downregulated in in vivo cultured parthenote blastocyst, using 3 fold-changes as a cut-off. While differentially upregulated expressed genes are related to transport and protein metabolic process, downregulated expressed genes are related to DNA and RNA binding. Using microarray data, 6 imprinted genes were identified as conserved among rabbits, humans and mice: GRB10, ATP10A, ZNF215, NDN, IMPACT and SFMBT2. We also found that 26 putative genes have at least one member of that gene family imprinted in other species. These data strengthen the view that a large fraction of genes is differentially expressed between parthenogenetic and normal embryos cultured under the same conditions and offer a new approach to the identification of imprinted genes in rabbit.

Naturil-Alfonso, Carmen; Saenz-de-Juano, Maria dels Desamparats; Penaranda, David S.

2012-01-01

349

Hydrogen peroxide as a mediator of programmed cell death in the blastocyst.  

PubMed

Previous work identified in blastocele fluid a soluble activity which killed embryonal carcinoma cells with trophectodermal potential but not those with embryonic potential [35]. From use of a malignant caricature of the late blastocyst, this toxic activity was postulated to be H2O2 [8]. The purpose of this paper was to determine if blastocele fluid also contained amounts of H2O2 capable of mediating the preferential killing of malignant pretrophectodermal cells (ECa 247). We not only observed that blastocele fluid is not toxic for these cells in the presence of catalase, but that malignant cells with embryonic potential (P19) that normally survive exposure to blastocele fluid become sensitive to it if their intracellular glutathione levels are lowered. Thus, it is concluded that the blastocyst contains amounts of H2O2 toxic to malignant pretrophectodermal cells and that glutathione-dependent mechanisms protect malignant inner cell mass cells with embryonic potential. Apparently, H2O2 production and glutathione-dependent protection mechanisms are developmentally regulated in the inner cell mass. These results are discussed with regards to apoptosis and the regulation of tissue mass. PMID:1655543

Pierce, G B; Parchment, R E; Lewellyn, A L

1991-04-01

350

Active cell movements coupled to positional induction are involved in lineage segregation in the mouse blastocyst  

PubMed Central

In the mouse blastocyst, some cells of the inner cell mass (ICM) develop into primitive endoderm (PE) at the surface, while deeper cells form the epiblast. It remained unclear whether the position of cells determines their fate, such that gene expression is adjusted to cell position, or if cells are pre-specified at random positions and then sort. We have tracked and characterised dynamics of all ICM cells from the early to late blastocyst stage. Time-lapse microscopy in H2B-EGFP embryos shows that a large proportion of ICM cells change position between the surface and deeper compartments. Most of this cell movement depends on actin and is associated with cell protrusions. We also find that while most cells are precursors for only one lineage, some give rise to both, indicating that lineage segregation is not complete in the early ICM. Finally, changing the expression levels of the PE marker Gata6 reveals that it is required in surface cells but not sufficient for the re-positioning of deeper cells. We provide evidence that Wnt9A, known to be expressed in the surface ICM, facilitates re-positioning of Gata6-expressing cells. Combining these experimental results with computer modelling suggests that PE formation involves both cell sorting movements and position-dependent induction.

Meilhac, Sigolene M.; Adams, Richard J.; Morris, Samantha A.; Danckaert, Anne; Le Garrec, Jean-Francois; Zernicka-Goetz, Magdalena

2012-01-01

351

Lysophosphatidic Acid Signaling in Late Cleavage and Blastocyst Stage Bovine Embryos  

PubMed Central

Lysophosphatidic acid (LPA) is a known cell signaling lipid mediator in reproductive tissues. In the cow, LPA is involved in luteal and early pregnancy maintenance. Here, we evaluated the presence and role of LPA in bovine early embryonic development. In relevant aspects, bovine embryos reflect more closely the scenario occurring in human embryos than the mouse model. Transcription of mRNA and protein expression of enzymes involved in LPA synthesis (ATX and cPLA2) and of LPA receptors (LPAR1–4) were detected in Days 5 and 8 in vitro produced embryos. Embryonic LPA production into culture medium was also detected at both stages of development. Supplementation of culture medium with LPA (10?5?M) between Days 2 and 8 had no effect on embryo yield and quality and on blastocyst relative mRNA abundance of genes involved in prostaglandin synthesis (PTGS2, PGES, and PGFS) and steroidogenesis (3?HSD). However, LPA treatment affected transcription levels of embryo quality markers, decreasing BAX (apoptotic) and increasing BCL2 (antiapoptotic) and IGF2R (growth marker) gene transcription levels. Blastocyst transcription of OCT4 (pluripotency marker) was not affected by LPA stimulation. In conclusion, LPA is an early bovine embryonic autocrine/paracrine signaling mediator, and LPA action may be relevant in early embryo-maternal interactions leading to embryonic survival.

Torres, Ana Catarina; Boruszewska, Dorota; Batista, Mariana; Kowalczyk-Zieba, Ilona; Sinderewicz, Emilia; Saulnier-Blache, Jean Sebastian; Woclawek-Potocka, Izabela; Lopes-da-Costa, Luis

2014-01-01

352

Blastocyst complementation generates exogenic pancreas in vivo in apancreatic cloned pigs  

PubMed Central

In the field of regenerative medicine, one of the ultimate goals is to generate functioning organs from pluripotent cells, such as ES cells or induced pluripotent stem cells (PSCs). We have recently generated functional pancreas and kidney from PSCs in pancreatogenesis- or nephrogenesis-disabled mice, providing proof of principle for organogenesis from PSCs in an embryo unable to form a specific organ. Key when applying the principles of in vivo generation to human organs is compensation for an empty developmental niche in large nonrodent mammals. Here, we show that the blastocyst complementation system can be applied in the pig using somatic cell cloning technology. Transgenic approaches permitted generation of porcine somatic cell cloned embryos with an apancreatic phenotype. Complementation of these embryos with allogenic blastomeres then created functioning pancreata in the vacant niches. These results clearly indicate that a missing organ can be generated from exogenous cells when functionally normal pluripotent cells chimerize a cloned dysorganogenetic embryo. The feasibility of blastocyst complementation using cloned porcine embryos allows experimentation toward the in vivo generation of functional organs from xenogenic PSCs in large animals.

Matsunari, Hitomi; Nagashima, Hiroshi; Watanabe, Masahito; Umeyama, Kazuhiro; Nakano, Kazuaki; Nagaya, Masaki; Kobayashi, Toshihiro; Yamaguchi, Tomoyuki; Sumazaki, Ryo; Herzenberg, Leonard A.; Nakauchi, Hiromitsu

2013-01-01

353

Lysophosphatidic acid signaling in late cleavage and blastocyst stage bovine embryos.  

PubMed

Lysophosphatidic acid (LPA) is a known cell signaling lipid mediator in reproductive tissues. In the cow, LPA is involved in luteal and early pregnancy maintenance. Here, we evaluated the presence and role of LPA in bovine early embryonic development. In relevant aspects, bovine embryos reflect more closely the scenario occurring in human embryos than the mouse model. Transcription of mRNA and protein expression of enzymes involved in LPA synthesis (ATX and cPLA2) and of LPA receptors (LPAR1-4) were detected in Days 5 and 8 in vitro produced embryos. Embryonic LPA production into culture medium was also detected at both stages of development. Supplementation of culture medium with LPA (10(-5)?M) between Days 2 and 8 had no effect on embryo yield and quality and on blastocyst relative mRNA abundance of genes involved in prostaglandin synthesis (PTGS2, PGES, and PGFS) and steroidogenesis (3?HSD). However, LPA treatment affected transcription levels of embryo quality markers, decreasing BAX (apoptotic) and increasing BCL2 (antiapoptotic) and IGF2R (growth marker) gene transcription levels. Blastocyst transcription of OCT4 (pluripotency marker) was not affected by LPA stimulation. In conclusion, LPA is an early bovine embryonic autocrine/paracrine signaling mediator, and LPA action may be relevant in early embryo-maternal interactions leading to embryonic survival. PMID:24833815

Torres, Ana Catarina; Boruszewska, Dorota; Batista, Mariana; Kowalczyk-Zieba, Ilona; Diniz, Patricia; Sinderewicz, Emilia; Saulnier-Blache, Jean Sebastian; Woclawek-Potocka, Izabela; Lopes-da-Costa, Luis

2014-01-01

354

In situ superexchange electron transfer through a single molecule: A rectifying effect  

PubMed Central

An increasingly comprehensive body of literature is being devoted to single-molecule bridge-mediated electronic nanojunctions, prompted by their prospective applications in molecular electronics and single-molecule analysis. These junctions may operate in gas phase or electrolyte solution (in situ). For biomolecules, the latter is much closer to their native environment. Convenient target molecules are aromatic molecules, peptides, oligonucleotides, transition metal complexes, and, broadly, molecules with repetitive units, for which the conducting orbitals are energetically well below electronic levels of the solvent. A key feature for these junctions is rectification in the current–voltage relation. A common view is that asymmetric molecules or asymmetric links to the electrodes are needed to acquire rectification. However, as we show here, this requirement could be different in situ, where a structurally symmetric system can provide rectification because of the Debye screening of the electric field in the nanogap if the screening length is smaller than the bridge length. The Galvani potentials of each electrode can be varied independently and lead to a transistor effect. We explore this behavior for the superexchange mechanism of electron transport, appropriate for a wide class of molecules. We also include the effect of conformational fluctuations on the lowest unoccupied molecular orbital (LUMO) energy levels; that gives rise to non-Arrhenius temperature dependence of the conductance, affected by the molecule length. Our study offers an analytical formula for the current–voltage characteristics that demonstrates all these features. A detailed physical interpretation of the results is given with a discussion of reported experimental data.

Kornyshev, Alexei A.; Kuznetsov, Alexander M.; Ulstrup, Jens

2006-01-01

355

Derivation of buffalo embryonic stem-like cells from in vitro-produced blastocysts on homologous and heterologous feeder cells  

Microsoft Academic Search

Purpose  The aim of the present study is to compare the ability of homologous and heterologous embryonic fibroblast feeder layers to\\u000a support isolation and proliferation of buffalo ES-like cells generated from hatched and expanded blastocysts produced by in\\u000a vitro fertilization and characterization of derived cells through expression of pluripotent markers.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Embryonic stem cells were derived from hatched and expanded blastocysts through

Dharmendra Kumar; T. Anand; K. P. Singh; M. K. Singh; R. A. Shah; M. S. Chauhan; P. Palta; S. K. Singla; R. S. Manik

356

SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications  

SciTech Connect

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.

Onar, Omer C [ORNL] [ORNL; Tang, Lixin [ORNL] [ORNL; Chinthavali, Madhu Sudhan [ORNL] [ORNL; Campbell, Steven L [ORNL] [ORNL; Miller (JNJ), John M. [JNJ-Miller PLC] [JNJ-Miller PLC

2014-01-01

357

Heat transfer and oil flow studies on a single-stage-to-orbit control-configured winged entry vehicle  

NASA Technical Reports Server (NTRS)

Results are presented for oil flow and phase change paint heat transfer tests conducted on a 0.006 scale model of a proposed single stage to orbit control configured vehicle. The data were taken at angles of attack up to 40 deg at a free stream Mach number of 10 for Reynolds numbers based on model length of 0.5 x 10 to the 6th power, 1.0 x 10 to the 6th power and 2.0 x 10 to the 6th power. The magnitude and distribution of heating are characterized in terms of angle of attack and Reynolds number aided by an analysis of the flow data which are used to suggest the presence of various three dimensional flow structures that produce the observed heating patterns. Of particular interest are streak heating patterns that result in high localized heat transfer rates on the wing windward surface at low to moderate angles of attack. These streaks are caused by the bow-shock/wing-shock interaction and formation of the wing-shock. Embedded vorticity was found to be associated with these interactions.

Helms, V. T., III; Bradley, P. F.

1984-01-01

358

Kinetic analysis of electron transfer across single water-microdroplet/oil and oil-microdroplet/water interfaces.  

PubMed

Using techniques comprising laser trapping, microcapillary injection/manipulation, fluorescence microspectroscopy and electrochemistry of single microdroplets, we kinetically investigated the electron transfer (ET) reaction between decamethylferrocene in tributyl phosphate and hexacyanoferrate(III) in water. In the oil-microdroplet/water system, the overall ET reaction rate significantly depended on the droplet radius (r(d), 0.5 microm < r(d) < 10 microm) and on the potential-determining ion concentration in the oil phase. The interfacial ET reaction rate constant determined in the water-microdroplet (r(d) = 21 microm)/oil system agreed very well with that in the oil-microdroplet (r(d) > 2 microm)/water system. The rate constant values were extremely small in the Gibbs free energy (DeltaG) range of -10 to -25 kJ mol(-1), with DeltaG consisting of the Galvani potential difference between the water and oil phases and the redox potential difference of the solutes. The characteristic ET reaction was discussed in terms of the ion transfer and the ET across the interfacial mixed layer with nanometer-sized thickness. PMID:19212051

Nakatani, Kiyoharu; Uchino, Mitsuharu; Suzuki, Shingo; Negishi, Takayuki; Osakai, Toshiyuki

2009-02-01

359

In vitro maturation, fertilization and culture to blastocysts of bovine oocytes in protein-free media.  

PubMed

This study examined the role of protein supplementation at the various steps of the in vitro production of bovine embryos derived from two different morphological categories of COC. The basic medium was TCM 199 and was supplemented with hormones during maturation in vitro and either estrous cow serum (ECS), bovine serum albumin (BSA) at various concentrations or polyvinyl-alcohol (PVA). Fertilization in vitro was carried out using frozen-thawed semen or one bull in Fert-talp containing heparin, hypotaurin and epinephrine and either 6 mg/ml BSA or 1 mg/ml PVA. In vitro culture up to the blastocyst stage was performed in TCM 199 supplemented with either ECS, BSA or PVA. The first experiment investigated the influence of different medium-supplements (ECS, BSA or PVA) on nuclear maturation and revealed no significant differences among treatment groups nor between categories of COC (63.9% to 74.9% and 48.9% to 77.0%, respectively). The time course of in vitro fertilization was elucidated in Experiment 2 in medium supplemented with either protein or PVA during maturation and fertilization. Penetration was not affected (70.9% to 79.3% penetration 12 h after onset of oocyte-sperm-co-incubation), but formation of pronuclei was decreased (P < 0.05) 12 and 19 h after onset of oocyte-sperm-co-incubation and was retarded in medium supplemented with PVA (12 h: 63.8 vs 21.4 %; 19 h: 57.5 vs 20.8 %, respectively) while cleavage was not affected. In Experiment 3, six treatment groups were formed in which the two different morphological categories of cumulus-oocyte-complexes (COC) were incubated in basic medium supplemented with 1) ECS during maturation and embryo culture and BSA during fertilization; 2) PVA during maturation and embryo culture, fertilization medium with PVA; 3) PVA during maturation and embryo culture, fertilization medium with BSA; 4) BSA (1 mg/ml) during maturation, fertilization and embryo culture; 5) BSA (6 mg/ml) during maturation, fertilization and embryo culture; and 6) BSA (10 mg/ml) during maturation, fertilization and embryo culture. The rates of cleavage and the development to morulae or blastocysts did not differ (P > 0.05) among treatment groups and between both categories of COC and were showing a high degree of variability (cleavage 54.0% to 65.1% and 41.3% to 55.7%, respectively; morulae 25.3% to 53.0% and 26.0% to 51.2%, respectively; blastocysts 5.4% to 24.7% and 0.6% to 20.3%, respectively). Parthenogenetic activation only rarely occurred in medium containing PVA throughout all steps of in vitro production of bovine embryos (Experiment 4) and led to early cleavage stages (8%), but no development to morula- or blastocyst-stages was observed. It is concluded that 1) formation of pronuclei was retarded in medium lacking protein-supplementation, indicating that BSA is required for regular fertilization in vitro and 2) under our experimental conditions, protein-supplementation is not necessary for maturation and development up to the blastocyst stage in vitro. PMID:16727707

Eckert, J; Niemann, H

1995-05-01

360

Spectroscopic Factors from the Single Neutron Transfer Reaction 111Cd(d,p)112Cd  

NASA Astrophysics Data System (ADS)

The cadmium isotopes have been cited as excellent examples of vibrational nuclei for decades, with multi-phonon quadrupole, quadrupole-octupole, and mixed-symmetry states proposed. From a variety of experimental studies, a large amount of spectroscopic data has been obtained, recently focused on ?-ray studies. In the present work, the single-particle structure of 112Cd has been investigated using the 111Cd(?cd, p)112Cd reaction. The investigation was carried out using a 22 MeV beam of polarized deuterons obtained from the Maier-Leibnitz Laboratory at Garching, Germany. The reaction ejectiles were momentum analyzed using a Q3D spectrograph, and 115 levels have been identified up to 4.2 MeV of excitation energy. Spin-parity has been assigned to each analyzed level, and angular distributions for the reaction cross sections and analyzing powers were obtained. Many additional levels have been observed compared with the previous (d,p) study performed with 8 MeV deuterons,1 including strongly populated 5- and 6- states. The former was previously assigned as a member of the quadrupole-octupole quintuplet, based on a strongly enhanced B(E2) value to the 3- state, but is now re-assigned as being predominately s1/2 ? h11/2 configuration.

Jamieson, D. S.; Garrett, P. E.; Demand, G. A.; Finlay, P.; Green, K. L.; Leach, K. G.; Phillips, A. A.; Svensson, C. E.; Sumithrarachchi, C. S.; Triambak, S.; Wong, J.; Ball, G.; Faestermann, T.; Krücken, R.; Hertenberger, R.; Wirth, H.-F.

2013-03-01

361

Dendrimer-functionalized single-wall carbon nanotubes: synthesis, characterization, and photoinduced electron transfer.  

PubMed

We describe the synthesis and characterization of a series of single-wall carbon nanotubes (SWNTs) functionalized with polyamidoamine dendrimers. Importantly, the dendrimers are linked directly to the SWNT surface using a divergent methodology. This approach allows the number of functional groups on the nanotubes to be increased without provoking significant damage to the conjugated pi-system of the SWNTs. Several tetraphenylporphyrin moieties can be linked to the periphery of the dendrimers, and the photophysical properties of the resulting nanoconjugates have been investigated with a series of steady-state and time-resolved spectroscopy. The fluorescence kinetics provide evidence for two transient decays, one very short-lived (i.e., 0.04 +/- 0.01 ns) and one long-lived (i.e., 8.6 +/- 1.2 ns). A possible explanation is that some porphyrin units do not interact with the nanotubes, thus exhibiting a fluorescence lifetime similar to that of the free porphyrin. Complementary transient absorption measurements not only corroborate the fast decay of the photoexcited tetraphenylporphyrin but also confirm that intraconjugate charge separation evolves from the excited porphyrin to the SWNTs. PMID:16984205

Campidelli, Stéphane; Sooambar, Chloé; Lozano Diz, Enrique; Ehli, Christian; Guldi, Dirk M; Prato, Maurizio

2006-09-27

362

Experimental and theoretical studies of the He(2+)-He system - Differential cross sections for direct, single-, and double-charge-transfer scattering at keV energies  

NASA Technical Reports Server (NTRS)

Measurements and calculations of differential cross sections for direct scattering, single-charge transfer, and double-charge transfer in collisions of 1.5-, 2.0-, 6.0-, and 10.0-keV (He-3)2+ with an He-4 target are reported. The measurements cover laboratory scattering angles below 1.5 deg with an angular resolution of about 0.03 deg. A quantum-mechanical molecular-state representation is employed in the calculations; in the case of single-charge transfer a two-state close-coupling calculation is carried out taking into account electron-translation effects. The theoretical calculations agree well with the experimental results for direct scattering and double-charge transfer. The present calculation identifies the origins of oscillatory structures observed in the differential cross sections.

Gao, R. S.; Dutta, C. M.; Lane, N. F.; Smith, K. A.; Stebbings, R. F.; Kimura, M.

1992-01-01

363

Sodium current in single cells from bullfrog atrium: voltage dependence and ion transfer properties.  

PubMed Central

1. Whole-cell and patch-clamp techniques (Hamill, Marty, Neher, Sakmann & Sigworth, 1981) have been used to make quantitative measurements of the transient inward sodium current (INa) in single cells from bullfrog atrium. This preparation is particularly suitable for the study of INa: (i) the current density is relatively low, (ii) the cells lack a transverse tubule system, (iii) isolated myocytes can be maintained at reduced temperatures (approximately 8-12 degrees C); therefore kinetics can be studied quantitatively. 2. INa was pharmacologically and kinetically isolated from other transmembrane currents by blocking ICa with CdCl2 (0.2-0.5 mM) or LaCl3 (5 x 10(-6) M), and by using only relatively short voltage-clamp depolarizations which did not activate IK (the delayed rectifier). 3. The voltage dependence of INa in bullfrog atrium is similar to that in amphibian node of Ranvier or fast skeletal muscle. The threshold for activation is approximately -50 mV. The peak of the INa vs. membrane potential relation is near -5 to -10 mV. The reversal potential in 'normal' (115 mM-Na+) Ringer solution is +59.0 mV (S.D. +/- 3.4, n = 10). Reduction of external Na+ concentration to one-third of normal resulted in an approximately -27 mV shift of the reversal potential, close to that expected for a highly Na+-selective conductance. 4. Steady-state inactivation of INa (h infinity), measured with a conventional two-pulse voltage-clamp protocol, spanned the membrane potential range from -90 to -50 mV. The potential dependence of h infinity was well described by a single Boltzmann function with half-inactivation at -71 mV and maximum slope of 6.0 mV. 5. Steady-state activation of INa (m infinity) was determined from fits of INa records to a Hodgkin-Huxley model. The potential dependence of m infinity was fitted to a Boltzmann function with half-activation at -33 mV and maximum slope of 9.5 mV. Thus at temperatures around 10 degrees C there was very little overlap of the m infinity and h infinity curves, and only very small steady-state 'window' currents are predicted. 6. The activation time constant, tau m, had a 'bell-shaped' dependence on membrane potential. The peak value of tau m was about 4.2 ms, at a membrane potential of -35 mV (9 degrees C). 7. The time course of inactivation of INa was consistently better described by the sum of two exponentials than by one exponential.(ABSTRACT TRUNCATED AT 400 WORDS)

Clark, R B; Giles, W

1987-01-01

364

Evidence for extensive single-electron-transfer chemistry in boryl anions: isolation and reactivity of a neutral borole radical.  

PubMed

Despite the synthesis of a boryl anion by Yamashita et?al. in 2006, compounds that show boron-centered nucleophilicity are still rare and sought-after synthetic goals. A number of such boryl anions have since been prepared, two of which were reported to react with methyl iodide in apparent nucleophilic substitution reactions. One of these, a borolyl anion based on the borole framework, has now been found to display single-electron-transfer (SET) reactivity in its reaction with triorganotetrel halides, which was confirmed by the isolation of the first neutral borole-based radical. The radical was characterized by elemental analysis, single-crystal X-ray crystallography, and EPR spectroscopy, and has implications for the understanding of boron-based nucleophilic behavior and the emergent role of boron radicals in synthesis. This radical reactivity was also exploited in the synthesis of compounds with rare B?Sn and B?Pb bonds, the latter of which was the first isolated and structurally characterized compound with a "noncluster" B?Pb bond. PMID:24719250

Bertermann, Rüdiger; Braunschweig, Holger; Dewhurst, Rian D; Hörl, Christian; Kramer, Thomas; Krummenacher, Ivo

2014-05-19

365

Fluorescence resonance energy transfer on single living cells. Application to binding of monovalent haptens to cell-bound immunoglobulin E.  

PubMed Central

We have determined the specific binding of 2,4-dinitrophenyl (DNP)-haptens to two different monoclonal immunoglobulin (IgE) molecules bound to Fc epsilon-receptors on the cell surface of single, living rat basophilic leukemia cells subclone 2H3 cells. The measurements were performed at 4 degrees, 15 degrees, and 25 degrees C using a recently developed technique that permits the quantitative determination of fluorescence resonance energy transfer between two fluorophores on single cells in a microscope from the photobleaching kinetics of the donor fluorophore. We introduce here a method for performing binding studies on individual attached cells. At 25 degrees C, the titration studies yielded equilibrium binding constants Kint of 9 x 10(8), 8 x 10(8), and 8 x 10(7) M-1 for the monovalent haptens N-2,4-DNP-epsilon-amino-n-caproic acid, N epsilon-2,4-DNP-L-lysine, and N-2,4-DNP-gamma-amino-n-butyric acid, respectively. Our data indicate that the affinity constants for the first two haptens binding to IgE on adherent cells are 4 to 11 times larger than that of the corresponding values obtained by fluorescence quenching experiments with the same haptens and IgE molecules either in solution or bound to cells in suspension.

Kubitscheck, U; Kircheis, M; Schweitzer-Stenner, R; Dreybrodt, W; Jovin, T M; Pecht, I

1991-01-01

366

Quantum dots for single-pair fluorescence resonance energy transfer in membrane- integrated EFoF1.  

PubMed

spFRET (single-pair fluorescence resonance energy transfer) with organic fluorophores has been used to demonstrate rotation of the subunits gamma and epsilon in membrane-integrated FoF1 during proton transport-coupled ATP synthesis. Owing to the high light intensities used in single-molecule spectroscopy, organic fluorophores show a high probability for photobleaching. Luminescent CdSe/ZnS nanocrystals with a hydrophilic shell have been covalently bound to FoF1 either to the stator subunit b or to the rotor subunit c. TIRFM (total internal reflection microscopy) shows that covalent binding of the QD (quantum dot) via cysteine to FoF1 leads to a significant decrease in the blinking probability in the microsecond-to-second time range. This effect allows the observation of subunit movements in an extended time range. If the QD is bound to the rotor subunit c, the fluorescence anisotropy shows fluctuations in the presence of ATP, in contrast with the constant anisotropy observed in the absence of ATP. PMID:18793181

Galvez, Eva; Düser, Monika; Börsch, Michael; Wrachtrup, Jörg; Gräber, Peter

2008-10-01

367

A numerical analysis of solid-liquid phase change heat transfer around a single and two horizontal, vertically spaced cylinders in a rectangular cavity  

Microsoft Academic Search

In the present study, a new numerical model is proposed to analyze solid-liquid phase change heat transfer in a complicated geometry. The present model can treat the solid\\/liquid phase change heat transfer with\\/without porous media, as well as conventional transient natural convection with\\/without porous media. Solidification calculations of pure water (without porous media) around a single cylinder and two cylinders

R. Viskanta

1997-01-01

368

Single dose pharmacokinetics, pharmacodynamics, tolerability and safety of BAY 60-5521, a potent inhibitor of cholesteryl ester transfer protein  

PubMed Central

AIMS To determine pharmacokinetics (PK), pharmacodynamics (PD), tolerability and safety of BAY 60–5521, a potent inhibitor of cholesteryl ester transfer protein (CETP). METHODS The first in man (FIM) study investigated the safety, tolerability, pharmacodynamics and pharmacokinetics in healthy male subjects following administration of single oral doses. The study was performed using a randomized, single-blind, placebo-controlled, single dose-escalation design. Thirty-eight young healthy male subjects (aged 20–45 years) received an oral dose of 5, 12.5, 25 or 50 mg BAY 60–5521 (n = 28) or were treated with a placebo (n = 10). RESULTS In all four dose steps, only one adverse event (25 mg; mild skin rash) was considered drug related. Clinical laboratory parameters showed no clinically relevant changes. A clear dose-dependent CETP inhibition could be demonstrated starting at a dose of 5 mg. At a dose of 25 mg, a CETP inhibition >50% over 18 h was observed. After 50 mg, CETP inhibition >50% lasted more than 50 h. Twenty-four h after administration mean HDL-C-values showed a nearly dose-proportional increase. Following administration of 50 mg, a significant HDL-C increase of about 30% relative to baseline values was found. BAY 60–5521 was slowly absorbed reaching maximum concentrations in plasma after 4 to 6 h. The disposition in plasma was multi-exponential with an estimated mean terminal half-life of 76 to 144 h. CONCLUSIONS BAY 60–5521 was clinically safe and well tolerated. No effects on heart rate, blood pressure and ECG recordings were observed during the study. A clear pharmacodynamic effect on CETP inhibition and HDL could be demonstrated.

Boettcher, Michael-Friedrich; Heinig, Roland; Schmeck, Carsten; Kohlsdorfer, Christian; Ludwig, Matthias; Schaefer, Anja; Gelfert-Peukert, Sabine; Wensing, Georg; Weber, Olaf

2012-01-01

369

Duration and temperature of culture medium equilibration affect frequency of blastocyst development.  

PubMed

Hamster 2-cell embryos were cultured in 50 microl drops of chemically defined medium (HECM-9) under oil in 60 mm Petri dishes. In the first experiment, the dishes were equilibrated with 5% O(2) /10% CO(2) /85% N(2) for 2 h either within sealed plastic bags or exposed directly to the same gas mixture in a tissue culture incubator. After culture of embryos for 48 h, there was no difference in development to the blastocyst stage. In the second experiment, the dishes were first equilibrated with 5% O(2) /10% CO(2) / 85% N(2) within sealed plastic bags, (A) at 4 degrees C overnight (16-18 h), or (B) at 37.5 degrees C overnight or (C) at 37.5 degrees C for 2 h. Dishes in treatment A were placed in the incubator at 37.5 degrees C for 2 h next day just before use. Two-cell embryos from a superovulated, mated female were equally distributed among the three treatments, then the dishes were sealed in fresh bags containing the same gas mixture and incubated at 37.5 degrees C for 48 h. This experiment was replicated 13 times with a total of 20 females and 268-275 embryos/treatment. There was no significant difference among the treatments for development to the (combined) morula/blastocyst stages. However, the percentage of blastocysts that developed in culture dishes that had been equilibrated overnight at 37.5 degrees C (treatment B) was significantly lower [50 +/- 14% (SEM)] than in treatments A and C, which were not different from one another (67 +/- 11 and 60 +/- 17% respectively). These results indicate that when culture medium is incubated at 37.5 degrees C overnight, chemical deterioration occurs that is detrimental to embryo development, and that this can be avoided by equilibrating dishes at 4 degrees C overnight, followed by a brief period at 37.5 degrees C to warm the medium before inserting embryos. This finding may have clinical relevance for human embryo culture. The study also demonstrates the utility and advantages of the sealed bag system for embryo culture. PMID:15705308

Bavister, Barry D; Poole, Kimberley A

2005-01-01

370

Recovery of mare oocytes on a fixed biweekly schedule, and resulting blastocyst formation after intracytoplasmic sperm injection  

Microsoft Academic Search

Oocytes may be collected from live mares from either the stimulated preovulatory follicle or from all visible immature follicles. We evaluated the yield of mature oocytes, and of blastocysts after intracytoplasmic sperm injection (ICSI), for both follicle types. In Experiment 1, mares were assigned to Progesterone (1.2g biorelease progesterone weekly) or Control treatments. Transvaginal aspiration of all follicles was performed

Candace C. Jacobson; Young-Ho Choi; Shelby S. Hayden; Katrin Hinrichs

2010-01-01

371

Effect of the in vitro culture system on the kinetics of blastocyst development and sex ratio of bovine embryos  

Microsoft Academic Search

Bovine blastocysts were produced using 6 different systems: 5 commonly used in vitro culture systems (synthetic oviduct fluid medium - SOF - without fetal calf serum, SOF supplemented with 10% serum for the entire culture period, SOF supplemented with 10% serum from Day 4 of culture, M199 coculture with bovine oviduct epithelial cells, M199 coculture with granulosa cell monolayer) and

A. Gutiérrez-Adán; P. Lonergan; D. Rizos; F. A. Ward; M. P. Boland; B. Pintado; J. de la Fuente

2001-01-01

372

Births after vitrification at morula and blastocyst stages: effect of artificial reduction of the blastocoelic cavity before vitrification  

Microsoft Academic Search

BACKGROUND: In 1996, with the introduction of sequential media, we set up a programme of cryopreservation of supernumerary morulae (day 4) and blastocysts (day 5) using a vitrification procedure. Our results showed that the efficiency of the vitrification method was dependent on the stage of embryo development and was negatively correlated with the expansion of the blastocoele. We postulated that

P. Vanderzwalmen; G. Bertin; Ch. Debauche; V. Standaert; E. van Roosendaal; M. Vandervorst; N. Bollen; H. Zech; T. Mukaida; K. Takahashi; R. Schoysman

2002-01-01

373

The impact of exposure to serum lipids during in vitro culture on the transcriptome of bovine blastocysts.  

PubMed

In vitro culture has a detrimental impact on early embryonic development, and serum addition to IVC is recognized to compromise blastocyst quality. Particularly, serum fatty acids affect embryonic lipid composition and reduce cryopreservation survival. To understand the molecular pathways of serum-induced embryonic stress, this study examined the early development of bovine embryos produced in different protein- or lipid-supplemented culture media: BSA alone (control), BSA + serum lipid fraction (SELF), delipidated serum and total serum. These protein-lipid treatments were applied from the eight to 16 cell stages to the blastocyst stage. As planned, SELF treatment increased the fatty acid concentration in the medium compared with control medium but did not induce embryo toxicity. However, microarray comparison between blastocysts cultured in BSA without or with SELF revealed differential transcriptomic profile associated with ceramide-induced oxidative stress and inflammation. Moreover, the SELF treatment had a significant impact on genes involved in cholesterol metabolism (LDLR, HMGCS1), with the potential upstream control of the transcription factors SREBP and PPARA, two major regulators of cholesterol metabolism. In addition, the expression of pluripotence-related genes (APEX, CLDN6) was downregulated in blastocysts subjected to either SELF or total serum. Taken together, these results illustrate how the early embryonic transcriptome responds to increased lipid exposure through an inflammatory and metabolic signature. PMID:24439163

Cagnone, Gael; Sirard, Marc-André

2014-03-15

374

Evaluation of activation treatments for blastocyst production and birth of viable calves following bovine intracytoplasmic sperm injection  

Microsoft Academic Search

The objective of this study was to compare the effectiveness of different methods of bovine oocyte activation following intracytoplasmic sperm injection (ICSI) in terms of oocyte cleavage and blastocyst rates, and calf production. Oocytes were harvested, post mortem, from the ovaries of Japanese Black heifers or cows. ICSI was carried out using a piezo-electric actuator. The injected or sham-injected oocytes

T. Oikawa; N. Takada; T. Kikuchi; T. Numabe; M. Takenaka; T. Horiuchi

2005-01-01

375

Histone modifications and mRNA expression in the inner cell mass and trophectoderm of bovine blastocysts  

PubMed Central

Normal development depends on the precise sequence of changes in the configuration of chromatin; these are primarily related to specific biochemical modifications such as acetylation or methylation of histones and DNA methylation. While the role of DNA methylation during preimplantation development has been studied extensively, little is known about histone modifications related to early embryonic development. Here, we investigated gene-specific histone modifications in in vitro produced bovine blastocysts. Selected genes thought to be critical for bovine preimplantation development were examined and included POU5F1 (OCT4), NANOG, INFT, GAPDH, SLC2A3 and IGF1. We used chromatin immunoprecipitation from pools of bovine blastocysts to unravel several modifications of histone H3 in relation to mRNA expression profiles. We focused on the two cell compartments of the blastocyst, the inner cell mass (ICM) and the trophectoderm (TE). We show that gene expression patterns in the ICM and TE of the bovine blastocyst are consistent with histone modification patterns on the promoter of the corresponding genes. The data show a complex epigenetic pattern of promoter occupancy by transcriptionally permissive and repressive H3 modifications. These results pave the way to in-depth epigenetic studies of preimplantation embryos that are crucial to gain a better understanding of the epigenetic changes frequently observed after use of assisted reproductive technologies.

Herrmann, Doris; Dahl, John Arne; Lucas-Hahn, Andrea; Collas, Philippe; Niemann, Heiner

2013-01-01

376

Expression of E-Cadherin, Leukemia Inhibitory Factor and Progesterone Receptor in Mouse Blastocysts after Ovarian Stimulation  

PubMed Central

Objective: The appropriate interaction between a blastocyst and the endometrium is essential for successful implantation. Numerous factors, including hormone receptors (progesterone receptor), cytokines [leukemia inhibitory factors (LIF)], and adherence molecules such as E-cadherin are involved in the cross-talk that occurs between the embryo and endometrium. Studies show that a lack of these genes impact endometrial receptivity. In this study, we compare the expression levels of E-cadherin, LIF, and progesterone receptor (PgR) genes in blastocysts that have been obtained from superovulated mice to those obtained from natural cycles. Materials and Methods: In this experimental study, for the experimental group, a total of 17 virgin female NMRI mice (6- 8 weeks old) were injected with 7.5 IU pregnant mare serum gonadotropin (PMSG). Their blastocysts (approximately n= 120) were flushed out after 3.5 days, following administration of human chorionic gonadotropin (hCG). The control group consisted of blastocysts from 62 female mice that were mated with male mice. The natural cycle blastocysts were flushed out from the female mice uteri 3.5 days after mating. The expression levels of E-cadherin, LIF, t PgR genes were examined by quantitative real-time reverse-transcriptase polymerase chain reaction (RT-PCR). Data were analyzed by the student’s t-test (one sample t-test). Results: Expression levels of all studied genes were significantly lower in the hormone-treated group compared to the natural cycle blastocysts (p<0.05). Conclusion: Although ovarian stimulation is utilized to obtain more oocytes in ART cycles, it seems that this could disadvantageous to implantation because of the decrease in expression levels of certain genes. Because of the important roles of E-cadherin, LIF, and progesterone receptor in the implantation process, we have shown lower expression levels of these genes in mouse blastocysts obtained from ovarian-stimulated mice than those derived from the natural cycle. The results observed in this study have shown the possibility of an unfavorable effect on implantation and pregnancy rate.

Movaghar, Bahar; Askarian, Saeedeh

2012-01-01

377

The interplay between neutral exciton and charge transfer states in single-strand polyadenine: a quantum dynamical investigation.  

PubMed

We investigate the quantum dynamics of the internal conversion of excitons into charge transfer (CT) states in single-strand oligomers of adenine (An) of different length (n up to 10 units) excited by a short-time laser pulse. Calculations are based on a model vibronic Hamiltonian whose parameters are fitted to accurate time-dependent density functional theory (TD-DFT) calculations, which was shown to reproduce the experimental absorption spectrum with the increase of n. As a first step, we analyze the impact of the vibrational motion on the population transfer in the dimer, highlighting that it causes loss of coherence and slows down the dynamics. For longer oligomers we resort to a simplified approach considering only electronic states and solving the equation of motion for the density matrix driven by inter-state couplings. In this way we are able also to include phenomenologically dephasing terms that mainly simulate intra-molecular effects, and lifetimes of local excitations mimicking monomer-like decay processes. Relaxation effects, whose role is to drive the system towards the thermal equilibrium allowing population exchange among states, are deliberately not considered here, since the focus is on very short-time dynamics. We consider both the cases of an instantaneous and of a finite-time (full width at half maximum 50 fs) laser pulse. According to our calculations, the photoexcited oligomers exhibit a complex dynamics and CT population rises on a 20-30 fs timescale and it persists even on the picosecond timescale. CT population increases with the length of the oligomer and it is only weakly dependent on the relative stability of CT and exciton states (within a range of 1500 cm(-1)). The chain length already modifies the photoexcited dynamics for A2 and A4 systems, but this effect saturates for small n so that the A10 oligomer is also representative of longer chains. PMID:23842735

Santoro, Fabrizio; Improta, Roberto; Avila, Francisco; Segado, Mireia; Lami, Alessandro

2013-08-01

378

Introducing a single-cell-derived human mesenchymal stem cell line expressing hTERT after lentiviral gene transfer.  

PubMed

Human mesenchymal stem cells (hMSCs) can be readily isolated from bone marrow and differentiate into multiple tissues, making them a promising target for future cell and gene therapy applications. The low frequency of hMSCs in bone marrow necessitates their isolation and expansion in vitro prior to clinical use, but due to senescence-associated growth arrest during culture, limited cell numbers can be generated. The lifespan of hMSCs has been extended by ectopic expression of human telomerase reverse transcriptase (hTERT) using retroviral vectors. Since malignant transformation was observed in hMSCs and retroviral vectors cause insertional mutagenesis, we ectopically expressed hTERT using lentiviral gene transfer. Single-cell-derived hMSC clones expressing hTERT did not show malignant transformation in vitro and in vivo after extended culture periods. There were no changes observed in the expression of tumour suppressor genes and karyotype. Cultured hMSCs lack telomerase activity, but it was significantly increased by ectopic expression of hTERT. HTERT expression prevented hMSC senescence and the cells showed significantly higher and unlimited proliferation capacity. Even after an extended culture period, hMSCs expressing hTERT preserved their stem cells character as shown by osteogenic, adipogenic and chondrogenic differentiation. In summary, extending the lifespan of human mesenchymal stem cells by ectopic expression of hTERT using lentiviral gene transfer may be an attractive and safe way to generate appropriate cell numbers for cell and gene therapy applications. PMID:18318690

Böcker, Wolfgang; Yin, Zhanhai; Drosse, Inga; Haasters, Florian; Rossmann, Oliver; Wierer, Matthias; Popov, Cvetan; Locher, Melanie; Mutschler, Wolf; Docheva, Denitsa; Schieker, Matthias

2008-08-01

379

Evidence linking programmed cell death in the blastocyst to polyamine oxidation.  

PubMed

Programmed cell death occurs in the inner cell mass during blastulation concomitant with the loss of its trophectodermal potential, and blastocele fluid kills malignant inner cell mass cells with trophectodermal potential (ECa 247) but spares those with embryonic potential (P19). A previous study had shown that blastocele-like fluid from embryoid bodies of the teratocarcinoma C44 contains a low-molecular-weight cytotoxin that exhibits the same target-cell selectivity as normal blastocele fluid. The current paper shows that the preferential killing of cells with trophectodermal potential is caused by hydrogen peroxide generated during the oxidation of polyamines in the cyst fluid by amine oxidases. The greater resistance of cells with embryonic potential to hydrogen peroxide is due to glutathione-dependent mechanisms. These data lead to the conclusion that an amine oxidase in the blastocyst oxidizes polyamines in blastocele fluid, generating hydrogen peroxide which causes programmed cell death of normal and malignant cells with trophectodermal potential. PMID:2163934

Gramzinski, R A; Parchment, R E; Pierce, G B

1990-03-01

380

Oct4 cell-autonomously promotes primitive endoderm development in the mouse blastocyst  

PubMed Central

Summary In embryonic stem (ES) cells and in early mouse embryos, the transcription factor Oct4 is an essential regulator of pluripotency. Oct4 transcriptional targets have been described in ES cell lines; however, the molecular mechanisms by which Oct4 regulates establishment of pluripotency in the epiblast (EPI) have not been fully elucidated. Here we show that neither maternal nor zygotic Oct4 are required for formation of EPI cells in the blastocyst. Rather, Oct4 is first required for development of the primitive endoderm (PE), an extraembryonic lineage. EPI cells promote PE fate in neighboring cells by secreting Fgf4, and Oct4 is required for expression of Fgf4, but we show that Oct4 promotes PE development cell-autonomously, downstream of Fgf4 and Mapk. Finally, we show that Oct4 is required for expression of multiple EPI and PE genes, as well as multiple metabolic pathways essential for the continued growth of the preimplantation embryo.

Frum, Tristan; Halbisen, Michael A.; Wang, Chaoyang; Amiri, Hossein; Robson, Paul; Ralston, Amy

2014-01-01

381

Generation and characterization of epiblast stem cells from blastocyst-stage mouse embryos.  

PubMed

Mouse epiblast stem cells (EpiSCs) are pluripotent embryonic cells that can be used to interrogate developmental transitions that occur during gastrulation. EpiSCs can also be robustly differentiated into functional somatic and germ cell derivatives making them a useful tool for studying development and regenerative medicine. Typically, mouse EpiSCs are isolated from the early postimplantation epiblast around 5.5 days post coitum (dpc). This chapter describes the methods for isolation of mouse EpiSCs from preimplantation blastocyst-stage mouse embryos (3.5 dpc). This technique enables the routine ability to derive EpiSC lines as it is much less labor intensive than isolation of EpiSCs from the postimplantation epiblast. We also detail relevant assays used to characterize new EpiSC lines and distinguish them from mouse embryonic stem cells. PMID:23975801

Factor, Daniel C; Najm, Fadi J; Tesar, Paul J

2013-01-01

382

Impact of developmental stage at cryopreservation and transfer on clinical outcome of frozen embryo cycles.  

PubMed

Although several early IVF successes were achieved after transferring fully formed blastocysts, the majority of embryos replaced worldwide over the past 30 years have been at the cleavage stage. The programme at this study centre has previously found that delaying an embryo transfer to day 5 can reduce the chance for a high-order multiple gestation without compromising the pregnancy rate because fewer embryos can be replaced. To evaluate the impact of transfer day and embryonic stage at cryopreservation on cycle outcome, 6069 fresh and 706 frozen transfers from 2000-2006 performed at this study centre were retrospectively analysed. Approximately half of the fresh transfers were performed on day 3, with a shift to day-5 transfer over the study period with no change in cryopreservation incidence. Implantation, clinical pregnancy and live birth rates were significantly higher following day-5 transfer. When frozen-thawed embryos (2-cell to day-6 blastocysts) were transferred, acceptable pregnancy and live birth rates were achieved at all stages but thawed embryos transferred as day-5 blastocysts generated consistently higher clinical pregnancy and live birth rates. Transfer of embryos frozen on day 6 had the highest miscarriage and lowest live birth rates. Barring government regulation, an IVF programme's day for cryopreservation generally depends on its management of and success with fresh embryo transfer. PMID:20034419

Noyes, Nicole; Reh, Andrea; McCaffrey, Caroline; Tan, Orkun; Krey, Lewis

2009-01-01

383

Inner cell mass-specific expression of a cell adhesion molecule (PECAM-1/CD31) in the mouse blastocyst.  

PubMed

Platelet/Endothelial Cell Adhesion Molecule-1 (PECAM-1 or CD31) is thought to be a vascular-specific protein, but its function has not been clearly defined. Here, we demonstrate by using confocal immunofluorescence microscopy that PECAM-1 is first detected in the mouse blastocyst, which contains no vascular cells, and its expression is restricted to the pluripotent inner cell mass (ICM) cells. Expression is localized to cell-cell borders of the ICM and is detected at the very first signs of blastocoel formation. Consistent with these observations is that embryonic transcripts of PECAM-1 mRNA, as detected by RT-PCR, greatly increase during the morula-to-blastocyst transition and seven of the eight known alternatively spliced isoforms of PECAM-1 are expressed in the blastocyst. The synthesis of PECAM-1 is independent of compaction, cytokinesis, and DNA replication, as it is detected in embryos that are chronologically at the blastocyst stage following culture of 8-cell embryos in Ca2+-free medium, or medium containing cytochalasin D or aphidicolin, respectively. By the late blastocyst stage, PECAM-1 expression is restricted to the pluripotent epiblast, at which point it has a mutually exclusive expression pattern to that of type IV collagen, a basement membrane marker. The reduction in PECAM-1 transcripts in retinoic acid-induced differentiation of F9 teratocarcinoma cells, a model of epiblast-to-primitive endoderm differentiation, confirmed the epiblast-specific expression of PECAM-1. By the egg cylinder stage of development, at which point the epiblast is no longer pluripotent, PECAM-1 is not detected. This ICM-specific pattern of expression suggests a novel developmental role of PECAM-1 that is independent of its function in vascular ontogeny. PMID:11397002

Robson, P; Stein, P; Zhou, B; Schultz, R M; Baldwin, H S

2001-06-15

384

Defined media optimization for in vitro culture of bovine somatic cell nuclear transfer (SCNT) embryos.  

PubMed

The objective was to establish an efficient defined culture medium for bovine somatic cell nuclear transfer (SCNT) embryos. In this study, modified synthetic oviductal fluid (mSOF) without bovine serum albumin (BSA) was used as the basic culture medium (BCM), whereas the control medium was BCM with BSA. In Experiment 1, adding polyvinyl alcohol (PVA) to BCM supported development of SCNT embryos to blastocyst stage, but blastocyst formation rate and blastocyst cell number were both lower (P < 0.05) compared to the undefined group (6.1 vs. 32.6% and 67.3 ± 3.4 vs. 109.3 ± 4.5, respectively). In Experiment 2, myo-inositol, a combination of insulin, transferrin and selenium (ITS), and epidermal growth factor (EGF) were added separately to PVA-supplemented BCM. The blastocyst formation rate and blastocyst cell number of those three groups were dramatically improved compared with that of PVA-supplemented group in Experiment 1 (18.5, 23.0, 24.1 vs. 6.1% and 82.7 ± 2.0, 84.3 ± 4.2, 95.3 ± 3.8 vs. 67.3 ± 3.4, respectively, P < 0.05), but were still lower compared with that of undefined group (33.7% and 113.8 ± 3.4, P < 0.05). In Experiment 3, when a combination of myo-inositol, ITS and EGF were added to PVA-supplemented BCM, blastocyst formation rate and blastocyst cell number were similar to that of undefined group (30.4 vs. 31.1% and 109.3 ± 4.4 vs. 112.0 ± 3.6, P > 0.05). In Experiment 4, when blastocysts were cryopreserved and subsequently thawed, there were no significant differences between the optimized defined group (Experiment 3) and undefined group in survival rate and 24 and 48 h hatching blastocyst rates. Furthermore, there were no significant differences in expression levels of H19, HSP70 and BAX in blastocysts derived from optimized defined medium and undefined medium, although the relative expression abundance of IGF-2 was significantly decreased in the former. In conclusion, a defined culture medium containing PVA, myo-inositol, ITS, and EGF supported in vitro development of bovine SCNT embryos. PMID:23110954

Wang, Li-Jun; Xiong, Xian-Rong; Zhang, Hui; Li, Yan-Yan; Li, Qian; Wang, Yong-Sheng; Xu, Wen-Bing; Hua, Song; Zhang, Yong

2012-12-01

385

Rapid movement of water and cryoprotectants in pig expanded blastocysts via channel processes: its relevance to their higher tolerance to cryopreservation.  

PubMed

Pig oocytes and embryos are highly sensitive to cryopreservation; however, tolerance to cryopreservation increases in embryos at the expanded blastocyst stage. This increased tolerance may be attributed to a decrease in cytoplasmic lipid droplets at this stage. We previously showed that an increase in the permeability of the plasma membrane in mouse oocytes to water and cryoprotectants, caused by the artificial expression of aquaporin 3, an aquaglyceroporin, enhanced tolerance to cryopreservation. In the present study, we investigated whether membrane permeability was also involved in the tolerance of pig embryos to cryopreservation. The permeability of oocytes and morulae to water and glycerol was low, whereas that of expanded blastocysts was high. Activation energy for permeability to water, glycerol, ethylene glycol, and dimethyl sulfoxide was markedly lower for expanded blastocysts than for oocytes. This suggests that water and these cryoprotectants move through expanded blastocysts predominantly by facilitated diffusion and through oocytes predominantly by simple diffusion. Aquaporin 3 mRNA was expressed in expanded blastocysts abundantly, but less so in oocytes. On the other hand, the permeability of expanded blastocysts to propylene glycol was as low as that of oocytes, and activation energy for its permeability was similar to that of oocytes, which suggests that propylene glycol moves through oocytes and embryos predominantly by simple diffusion. These results suggest that the higher tolerance of pig expanded blastocysts to cryopreservation is also related to high membrane permeability due to the expression of water/cryoprotectant channels, in addition to the decrease in cytoplasmic lipid droplets. PMID:23966318

Jin, Bo; Higashiyama, Ryu-ichi; Nakata, Yu-ichi; Yonezawa, Jun-ichi; Xu, Shangdan; Miyake, Masashi; Takahashi, Sei-ichi; Kikuchi, Kazuhiro; Yazawa, Ken-ichi; Mizobuchi, Shuhei; Niimi, Saori; Kitayama, Mizuho; Koshimoto, Chihiro; Matsukawa, Kazutsugu; Kasai, Magosaburo; Edashige, Keisuke

2013-10-01

386

Molecular cytogenetic analysis of human blastocysts andcytotrophoblasts by multi-color FISH and Spectra Imaging analyses  

SciTech Connect

Numerical chromosome aberrations in gametes typically lead to failed fertilization, spontaneous abortion or a chromosomally abnormal fetus. By means of preimplantation genetic diagnosis (PGD), we now can screen human embryos in vitro for aneuploidy before transferring the embryos to the uterus. PGD allows us to select unaffected embryos for transfer and increases the implantation rate in in vitro fertilization programs. Molecular cytogenetic analyses using multi-color fluorescence in situ hybridization (FISH) of blastomeres have become the major tool for preimplantation genetic screening of aneuploidy. However, current FISH technology can test for only a small number of chromosome abnormalities and hitherto failed to increase the pregnancy rates as expected. We are in the process of developing technologies to score all 24 chromosomes in single cells within a 3 day time limit, which we believe is vital to the clinical setting. Also, human placental cytotrophoblasts (CTBs) at the fetal-maternal interface acquire aneuploidies as they differentiate to an invasive phenotype. About 20-50% of invasive CTB cells from uncomplicated pregnancies were found aneuploidy, suggesting that the acquisition of aneuploidy is an important component of normal placentation, perhaps limiting the proliferative and invasive potential of CTBs. Since most invasive CTBs are interphase cells and possess extreme heterogeneity, we applied multi-color FISH and repeated hybridizations to investigate individual CTBs. In summary, this study demonstrates the strength of Spectral Imaging analysis and repeated hybridizations, which provides a basis for full karyotype analysis of single interphase cells.

Weier, Jingly F.; Ferlatte, Christy; Baumgartner, Adolf; Jung,Christine J.; Nguyen, Ha-Nam; Chu, Lisa W.; Pedersen, Roger A.; Fisher,Susan J.; Weier, Heinz-Ulrich G.

2006-02-08

387

Bioimaging of geographically adjacent proteins in a single cell by quantum dot-based fluorescent resonance energy transfer.  

PubMed

Thousands of proteins are simultaneously involved in the maintenance of a single cancer cell. Fluorescent resonance energy transfer (FRET) is one of the most general techniques for imaging biologically interacting molecules in a cell. Here, we applied FRET to image the co-localization of two proteins that do not interact biologically (nucleolin and integrin ?(v) ?(3),) both of which are highly expressed in the plasma membrane of cancer cells. AS1411 aptamer, which targets nucleolin, was labeled by Cy3 (Cy3-AS1411) and arginine-glycine-aspartic acid (RGD) peptide, which targets integrin ?(v) ?(3) , was conjugated with quantum dot (525?nm, Qd) Qd arginine-glycine-aspartic acid (Qd-RGD). FRET activities between Cy3-AS1411 and Qd-RGD were measured in HeLa cells, a human cervical cancer cell line. FRET phenomena between Qd and Cy3 showed good compatibility according to proximity. The fluorescence signature using Qd-RGD and Cy3-AS1411 showed that nucleolin and integrin ?(v) ?(3) proteins were highly expressed in HeLa cells. Co-incubation of Qd-RGD and Cy3-AS1411 in a single HeLa cell demonstrated that the fluorescence overlay by FRET was quantitatively and geographically quite different from that of individual confocal images. These results suggest that Qd-based FRET analysis can provide information on geographical co-localization of proteins in naïve cells, which is very important for determining the molecular and cellular functions of genes involved in cancers and other clinical diseases. PMID:21136958

Kang, Won Jun; Ko, Mee Hyang; Lee, Dong Soo; Kim, Soonhag

2009-12-01

388

Dynamics and folding of single two-stranded coiled-coil peptides studied by fluorescent energy transfer confocal microscopy.  

PubMed

We report single-molecule measurements on the folding and unfolding conformational equilibrium distributions and dynamics of a disulfide crosslinked version of the two-stranded coiled coil from GCN4. The peptide has a fluorescent donor and acceptor at the N termini of its two chains and a Cys disulfide near its C terminus. Thus, folding brings the two N termini of the two chains close together, resulting in an enhancement of fluorescent resonant energy transfer. End-to-end distance distributions have thus been characterized under conditions where the peptide is nearly fully folded (0 M urea), unfolded (7.4 M urea), and in dynamic exchange between folded and unfolded states (3.0 M urea). The distributions have been compared for the peptide freely diffusing in solution and deposited onto aminopropyl silanized glass. As the urea concentration is increased, the mean end-to-end distance shifts to longer distances both in free solution and on the modified surface. The widths of these distributions indicate that the molecules are undergoing millisecond conformational fluctuations. Under all three conditions, these fluctuations gave nonexponential correlations on 1- to 100-ms time scale. A component of the correlation decay that was sensitive to the concentration of urea corresponded to that measured by bulk relaxation kinetics. The trajectories provided effective intramolecular diffusion coefficients as a function of the end-to-end distances for the folded and unfolded states. Single-molecule folding studies provide information concerning the distributions of conformational states in the folded, unfolded, and dynamically interconverting states. PMID:11087856

Talaga, D S; Lau, W L; Roder, H; Tang, J; Jia, Y; DeGrado, W F; Hochstrasser, R M

2000-11-21

389

Tracer tests in a fractured dolomite: 2. Analysis of mass transfer in single-well injection-withdrawal tests  

NASA Astrophysics Data System (ADS)

We investigated multiple-rate diffusion as a possible explanation for observed behavior in a suite of single-well injection-withdrawal (SWIW) tests conducted in a fractured dolomite. We first investigated the ability of a conventional double-porosity model and a multirate diffusion model to explain the data. This revealed that the multirate diffusion hypothesis/model is consistent with available data and is capable of matching all of the recovery curves. Second, we studied the sensitivity of the SWIW recovery curves to the distribution of diffusion rate coefficients and other parameters. We concluded that the SWIW test is very sensitive to the distribution of rate coefficients but is relatively insensitive to other flow and transport parameters such as advective porosity and dispersivity. Third, we examined the significance of the constant double-log late time slopes (-2.1 to -2.8), which are present in several data sets. The observed late time slopes are significantly different than would be predicted by either conventional double-porosity or single-porosity models and are believed to be a distinctive feature of multirate diffusion. Fourth, we found that the estimated distributions of diffusion rate coefficients are very broad, with the distributions spanning a range of up to 3.6 orders of magnitude. Fifth, when both heterogeneity and solute drift are present, late time behavior similar to multirate mass transfer can occur. Although it is clear that multirate diffusion occurs in the Culebra, the number of orders of magnitude of variability may be overestimated because of the combined effects of drift and heterogeneity.

Haggerty, Roy; Fleming, Sean W.; Meigs, Lucy C.; McKenna, Sean A.

2001-05-01

390

Dynamics and folding of single two-stranded coiled-coil peptides studied by fluorescent energy transfer confocal microscopy  

PubMed Central

We report single-molecule measurements on the folding and unfolding conformational equilibrium distributions and dynamics of a disulfide crosslinked version of the two-stranded coiled coil from GCN4. The peptide has a fluorescent donor and acceptor at the N termini of its two chains and a Cys disulfide near its C terminus. Thus, folding brings the two N termini of the two chains close together, resulting in an enhancement of fluorescent resonant energy transfer. End-to-end distance distributions have thus been characterized under conditions where the peptide is nearly fully folded (0 M urea), unfolded (7.4 M urea), and in dynamic exchange between folded and unfolded states (3.0 M urea). The distributions have been compared for the peptide freely diffusing in solution and deposited onto aminopropyl silanized glass. As the urea concentration is increased, the mean end-to-end distance shifts to longer distances both in free solution and on the modified surface. The widths of these distributions indicate that the molecules are undergoing millisecond conformational fluctuations. Under all three conditions, these fluctuations gave nonexponential correlations on 1- to 100-ms time scale. A component of the correlation decay that was sensitive to the concentration of urea corresponded to that measured by bulk relaxation kinetics. The trajectories provided effective intramolecular diffusion coefficients as a function of the end-to-end distances for the folded and unfolded states. Single-molecule folding studies provide information concerning the distributions of conformational states in the folded, unfolded, and dynamically interconverting states.

Talaga, David S.; Lau, Wai Leung; Roder, Heinrich; Tang, Jianyong; Jia, Yiwei; DeGrado, William F.; Hochstrasser, Robin M.

2000-01-01

391

Studies of single- and two-phase heat transfer in a blocked four-rod bundle. Final report. [PWR  

Microsoft Academic Search

Correlations have been developed for the heat transfer coefficient in the vicinity of flow blockages in rod bundles. The heat transfer data have been obtained on a four rod bundle with sleeve-type blockages for a Reynolds number range of 230 to 6900 and void fractions up to 0.15. Significant enhancement of the heat transfer coefficient has been observed downstream of

M. Drucker; V. K. Dhir

1984-01-01

392

Pregnancy rates and gravid uterine parameters in single, twin and triplet pregnancies in naturally bred ewes and ewes after transfer of in vitro produced embryos  

Microsoft Academic Search

The objectives of this study were to: (1) evaluate the pregnancy rates after transfer of embryos produced in the presence or absence of epidermal growth factor (EGF) during in vitro maturation, and (2) compare several variables of the gravid uterus on day 140 after fertilization in single, twin and triplet pregnancies in ewes (n=12) bred naturally and in ewes (n=18)

Anna T. Grazul-Bilska; Disha Pant; Justin S. Luther; Pawel P. Borowicz; Chainarong Navanukraw; Joel S. Caton; Marcy A. Ward; Dale A. Redmer; Lawrence P. Reynolds

2006-01-01

393

Expression of the Alpha Tocopherol Transfer Protein gene is regulated by Oxidative Stress and Common Single Nucleotide Polymorphisms  

PubMed Central

Vitamin E (?-tocopherol) is the major lipid soluble antioxidant in most animal species. By controlling the secretion of vitamin E from the liver, the ?-tocopherol transfer protein (?TTP) regulates whole-body distribution and levels of this vital nutrient. However, the mechanism(s) that regulate the expression of this protein are poorly understood. Here we report that transcription of the TTPA gene in immortalized human hepatocytes (IHH) is induced by oxidative stress and by hypoxia, by agonists of the nuclear receptors PPAR? and RXR, and by increased cAMP levels. The data show further that induction of TTPA transcription by oxidative stress is mediated by an already-present transcription factor, and does not require de novo protein synthesis. Silencing of the cAMP response element binding (CREB) transcription factor attenuated transcriptional responses of the TTPA gene to added peroxide, suggesting that CREB mediates responses of this gene to oxidative stress. Using a 1.9 Kb proximal segment of the human TTPA promoter together with site-directed mutagenesis approach, we found that single nucleotide polymorphisms (SNPs) that are commonly found in healthy humans dramatically affect promoter activity. These observations suggest that oxidative stress and individual genetic makeup contribute to vitamin E homeostasis in humans. These findings may explain the variable responses to vitamin E supplementation observed in human clinical trials.

Ulatowski, Lynn; Dreussi, Cara; Noy, Noa; Barnholtz-Sloan, Jill; Klein, Eric; Manor, Danny

2012-01-01

394

Electron-transfer sensitization of H2 oxidation and CO2 reduction catalysts using a single chromophore.  

PubMed

Energy-storing artificial-photosynthetic systems for CO2 reduction must derive the reducing equivalents from a renewable source rather than from sacrificial donors. To this end, a homogeneous, integrated chromophore/two-catalyst system is described that is thermodynamically capable of photochemically driving the energy-storing reverse water-gas shift reaction (CO2 + H2 ? CO + H2O), where the reducing equivalents are provided by renewable H2. The system consists of the chromophore zinc tetraphenylporphyrin (ZnTPP), H2 oxidation catalysts of the form [Cp(R)Cr(CO)3](-), and CO2 reduction catalysts of the type Re(bpy-4,4'-R2)(CO)3Cl. Using time-resolved spectroscopic methods, a comprehensive mechanistic and kinetic picture of the photoinitiated reactions of mixtures of these compounds has been developed. It has been found that absorption of a single photon by broadly absorbing ZnTPP sensitizes intercatalyst electron transfer to produce the substrate-active forms of each. The initial photochemical step is the heretofore unobserved reductive quenching of the low-energy T1 state of ZnTPP. Under the experimental conditions, the catalytically competent state decays with a second-order half-life of ?15 ?s, which is of the right magnitude for substrate trapping of sensitized catalyst intermediates. PMID:24961370

La Porte, Nathan T; Moravec, Davis B; Hopkins, Michael D

2014-07-01

395

A novel peptide delivers plasmids across blood-brain barrier into neuronal cells as a single-component transfer vector.  

PubMed

There is no data up to now to show that peptide can deliver plasmid into brain as a single-component transfer vector. Here we show that a novel peptide, RDP (consisted of 39 amino acids), can be exploited as an efficient plasmid vector for brain-targeting delivery. The plasmids containing Lac Z reporter gene (pVAX-Lac Z) and BDNF gene (pVAX-BDNF) are complexed with RDP and intravenously injected into mice. The results of gel retardation assay show that RDP enables to bind DNA in a dose-dependent manner, and the X-Gal staining identity that Lac Z is specifically expressed in the brain. Also, the results of Western blot and immunofluorescence staining of BDNF indicate that pVAX-BDNF complexed with RDP can be delivered into brain, and show neuroprotective properties in experimental Parkinson's disease (PD) model. The results demonstrate that RDP enables to bind and deliver DNA into the brain, resulting in specific gene expression in the neuronal cells. This strategy provides a novel, simple and effective approach for non-viral gene therapy of brain diseases. PMID:23555734

Fu, Ailing; Zhang, Miaomiao; Gao, Feiyan; Xu, Xingran; Chen, Zhangbao

2013-01-01

396

A homogeneous single-label quenching resonance energy transfer assay for a ?-opioid receptor-ligand using intact cells.  

PubMed

This study, a homogeneous assay system for delta opioid receptor binding ligands has been developed using Quenching Resonance Energy Transfer (QRET). The QRET system allows receptor-ligand binding assays on intact cells using a single-label approach and a nonspecific quenching mechanism. Binding of antagonists or agonists to the receptor can be defined using a europium(III) labeled ligand. In the presence of the unlabeled ligand the labeled ligand is displaced and remains in solution. The non-bound labeled ligand is not protected by the target receptor, and the luminescence signal is quenched. For this objective, a Eu(III) labeled peptide molecule with three different linkers (AX0, AX1 and AX2) was designed. Peptides were evaluated using the homogeneous QRET technique, radioligand binding assays and the heterogeneous time-resolved luminescence (TRL) technique. Using the Eu-AX0 peptide and the QRET method, a panel of opioid compounds (naltrexone, naltrindole, SCN-80, DPDPE and DAMGO) was tested to prove the assay performance. The signal-to-background ratio for the tested opioid ligand ranged from 3.3 to 12.0. The QRET method showed prominent performance also in high DMSO concentrations. QRET is a homogenous and a non-radioactive detection system for screening and this is the first attempt to utilize peptide ligands in the QRET concept. PMID:23800721

Kopra, Kari; Shweta; Martikkala, Eija; Hänninen, Pekka; Petäjä-Repo, Ulla; Härmä, Harri

2013-09-01

397

A Novel Peptide Delivers Plasmids across Blood-Brain Barrier into Neuronal Cells as a Single-Component Transfer Vector  

PubMed Central

There is no data up to now to show that peptide can deliver plasmid into brain as a single-component transfer vector. Here we show that a novel peptide, RDP (consisted of 39 amino acids), can be exploited as an efficient plasmid vector for brain-targeting delivery. The plasmids containing Lac Z reporter gene (pVAX-Lac Z) and BDNF gene (pVAX-BDNF) are complexed with RDP and intravenously injected into mice. The results of gel retardation assay show that RDP enables to bind DNA in a dose-dependent manner, and the X-Gal staining identity that Lac Z is specifically expressed in the brain. Also, the results of Western blot and immunofluorescence staining of BDNF indicate that pVAX-BDNF complexed with RDP can be delivered into brain, and show neuroprotective properties in experimental Parkinson’s disease (PD) model. The results demonstrate that RDP enables to bind and deliver DNA into the brain, resulting in specific gene expression in the neuronal cells. This strategy provides a novel, simple and effective approach for non-viral gene therapy of brain diseases.

Fu, Ailing; Zhang, Miaomiao; Gao, Feiyan; Xu, Xingran; Chen, Zhangbao

2013-01-01

398

A High-yield Two-step Transfer Printing Method for Large-scale Fabrication of Organic Single-crystal Devices on Arbitrary Substrates  

PubMed Central

Single-crystal organic nanostructures show promising applications in flexible and stretchable electronics, while their applications are impeded by the large incompatibility with the well-developed photolithography techniques. Here we report a novel two-step transfer printing (TTP) method for the construction of organic nanowires (NWs) based devices onto arbitrary substrates. Copper phthalocyanine (CuPc) NWs are first transfer-printed from the growth substrate to the desired receiver substrate by contact-printing (CP) method, and then electrode arrays are transfer-printed onto the resulting receiver substrate by etching-assisted transfer printing (ETP) method. By utilizing a thin copper (Cu) layer as sacrificial layer, microelectrodes fabricated on it via photolithography could be readily transferred to diverse conventional or non-conventional substrates that are not easily accessible before with a high transfer yield of near 100%. The ETP method also exhibits an extremely high flexibility; various electrodes such as Au, Ti, and Al etc. can be transferred, and almost all types of organic devices, such as resistors, Schottky diodes, and field-effect transistors (FETs), can be constructed on planar or complex curvilinear substrates. Significantly, these devices can function properly and exhibit closed or even superior performance than the device counterparts fabricated by conventional approach.

Deng, Wei; Zhang, Xiujuan; Pan, Huanhuan; Shang, Qixun; Wang, Jincheng; Zhang, Xiaohong; Zhang, Xiwei; Jie, Jiansheng

2014-01-01

399

A High-yield Two-step Transfer Printing Method for Large-scale Fabrication of Organic Single-crystal Devices on Arbitrary Substrates.  

PubMed

Single-crystal organic nanostructures show promising applications in flexible and stretchable electronics, while their applications are impeded by the large incompatibility with the well-developed photolithography techniques. Here we report a novel two-step transfer printing (TTP) method for the construction of organic nanowires (NWs) based devices onto arbitrary substrates. Copper phthalocyanine (CuPc) NWs are first transfer-printed from the growth substrate to the desired receiver substrate by contact-printing (CP) method, and then electrode arrays are transfer-printed onto the resulting receiver substrate by etching-assisted transfer printing (ETP) method. By utilizing a thin copper (Cu) layer as sacrificial layer, microelectrodes fabricated on it via photolithography could be readily transferred to diverse conventional or non-conventional substrates that are not easily accessible before with a high transfer yield of near 100%. The ETP method also exhibits an extremely high flexibility; various electrodes such as Au, Ti, and Al etc. can be transferred, and almost all types of organic devices, such as resistors, Schottky diodes, and field-effect transistors (FETs), can be constructed on planar or complex curvilinear substrates. Significantly, these devices can function properly and exhibit closed or even superior performance than the device counterparts fabricated by conventional approach. PMID:24942458

Deng, Wei; Zhang, Xiujuan; Pan, Huanhuan; Shang, Qixun; Wang, Jincheng; Zhang, Xiaohong; Zhang, Xiwei; Jie, Jiansheng

2014-01-01

400

Daily supplementation with ghrelin improves in vitro bovine blastocysts formation rate and alters gene expression related to embryo quality.  

PubMed

Ghrelin is a gastric peptide having regulatory role in the reproductive system functionality, acting mainly at central level. Because the expression of ghrelin system (ghrelin and its receptor) has been detected in the bovine ovary, the objectives of the present study were to investigate whether ghrelin can affect the developmental potential of in vitro-produced embryos, and to test their quality in terms of relative abundance of various genes related to metabolism, apoptosis and oxidation. In the first experiment, in vitro-produced zygotes were cultured in the absence (control [C]) and in the presence of three concentrations of acylated ghrelin (200 pg/mL [Ghr200], 800 pg/mL [Ghr800]; and 2000 pg/mL [Ghr2000]); blastocyst formation rates were examined on Days 7, 8, and 9. In the second experiment, only the 800 pg/mL dose of ghrelin was used. Zygotes were produced as in experiment 1 and 24 hours post insemination they were divided into 4 groups; in two groups (C; without ghrelin; Ghr800 with ghrelin), embryos were cultured without medium replacement; in the remaining two groups (Control N and GhrN), the culture medium was daily renewed. A pool of Day-7 blastocysts were snap frozen for relative mRNA abundance of various genes related to metabolism, oxidation, implantation, and apoptosis. In experiment 3, embryos were produced as in experiment 2, but in the absence of serum (semi-defined culture medium). In experiment 1, no differences were detected between C, Ghr200, and Ghr2000, although fewer blastocysts were produced in group Ghr800 compared with C. In experiment 2, the lowest blastocysts yield was found in Ghr800, whereas daily renewal of ghrelin (Ghr800N) resulted to increased blastocysts formation rate, which on Day 7 was the highest among groups (P < 0.05). In experiment 3, ghrelin significantly suppressed blastocysts yield. Significant differences were detected in various relative mRNA abundance, giving an overall final notion that embryos produced in the presence of ghrelin were of better quality than controls. Our results imply a specific role of ghrelin in early embryonic development; however, the specific mode of its action needs further investigation. PMID:24332928

Dovolou, Eleni; Periquesta, Eva; Messinis, Ioannis E; Tsiligianni, Theodora; Dafopoulos, Konstantinos; Gutierrez-Adan, Alfonso; Amiridis, Georgios S

2014-03-01