Advances in embryo culture platforms: novel approaches to improve preimplantation embryo development through modifications of the microenvironment

BACKGROUND

The majority of research aimed at improving embryo development in vitro has focused on manipulation of the chemical environment, examining details such as energy substrate composition and impact of various growth factors or other supplements. In comparison, relatively little work has been done examining the physical requirements of preimplantation embryos and the role culture platforms or devices can play in influencing embryo development.

METHODS

Electronic searches were performed using keywords centered on embryo culture techniques using PUBMED through June 2010 and references were searched for additional research articles.

RESULTS

Various approaches to in vitro embryo culture that involve manipulations of the physical culture environment are emerging. Novel culture platforms being developed examine issues such as media volume and embryo spacing. Furthermore, methods to permit dynamic embryo culture with fluid flow and embryo movement are now available, and novel culture surfaces are being tested.

CONCLUSIONS

Although several factors remain to be studied to optimize efficiency, manipulations of the embryo culture microenvironment through novel culture devices may offer a means to improve embryo development in vitro. Reduced volume systems that reduce embryo spacing, such as the well-of-the-well approach, appear beneficial, although more work is needed to verify the source of their true benefit in human embryos. Emerging microfluidic technology appears to be a promising approach. However, along with the work on specialized culture surfaces, more information is required to determine the impact on human embryo development.

Microfluidics for gametes, embryos, and embryonic stem cells

Microfluidics is a young but established field that holds significant potential for scientific discovery. The utility of microfluidics can improve our knowledge of basic biology as well as expand our understanding in specialized areas such as assisted reproduction and stem cell developmental biology. This review describes the technology of microfluidics and discusses applications within assisted reproduction technology and embryonic stem cell growth and directed differentiation. Development of an integrated microfluidic platform for assisted reproduction, which can manipulate gametes, embryos, embryonic stem cells, their culture environment, and incorporate biomarker analysis, could have a dramatic impact on the basic understanding of embryo/embryonic stem cell development, as well as provide significant improvements in current technologies used to treat infertility, preserve fertility, and derive therapeutic cells from stem cells.

Laboratory methods in the study of endometrial Claudin-4

Immunohistochemistry is a suitable method for the detection of proteins from the Claudin family and several antibodies are commercially available for the detection of Claudin congeners. Immunodetection of Caludin-4 in the paraffin-embedded specimens might be a useful tool for studying the role of these proteins in the cyclic transformation of the endometrium and its role in the endometrial receptivity; furthermore, other components of the junctional zone involved in the transformational process of the endometrium can be detected by means of immunohistochemistry/immunofluorescence with several polyclonal or monoclonal antibodies. The aim of this chapter is to comprehensively overview the materials and methods to perform the endometrial biopsy and to detect Claudin-4 in paraffin-embedded samples of endometrium. Additionally, the interpretation of the results is addressed.

Perceived stress and coronary heart disease risk factors: The contribution of socio-economic position

OBJECTIVES

The aim of this study was to explore the relationship between risk factors for coronary heart disease (CHD) and perceived stress, adjusted for socio-economic position.

DESIGN

Cross-sectional analysis of CHD risk factors, perceived stress and socio-economic position.

METHOD

A cohort of employed Scottish men (N = 5848) and women (N = 984) completed a questionnaire and attended a physical examination.

RESULTS

Higher socio-economic groups registered higher perceived stress scores. Perceived stress was associated with the following CHD risk factors in the expected direction: high plasma cholesterol, little recreational exercise, cigarette smoking, and high alcohol consumption. Contrary to expectations, stress was related negatively to high diastolic blood pressure, body mass index (BMI) and low forced expiratory volume. Correction for socio-economic position tended to abolish the associations between stress and physiological risk factors; the associations between stress and behavioural risk factors withstood such correction. The residual patterns of associations between perceived stress and CHD risk were broadly similar for men and women. A lower BMI, a greater number of cigarettes smoked, and greater alcohol consumption were associated with higher levels of perceived stress for both sexes. Lower levels of recreational exercise were associated with higher levels of stress for men only.

CONCLUSIONS

Self-reported stress is related to health-related behaviours and to physiological CHD risk factors. The direction of the association with physiological risk was often contrary to expectation and appeared to be largely due to confounding by socio-economic position. In contrast, the association with health-related behaviours was in the expected direction and was largely independent of such confounding.

Tensor correlations measured in 3He(e,e' pp)n

We have measured the 3He(e,e' pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum p(tot). For pair relative momenta between 0.3 and 0.5  GeV/c, the ratio is very small at low p(tot) and rises to approximately 0.5 at large p(tot). This shows the dominance of tensor over central correlations at this relative momentum.

Absorption of the ω and ϕ mesons in nuclei

Because of their long lifetimes, the ω and ϕ mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from 2H, C, Ti, Fe, and Pb targets. This Letter reports the first measurement of the ratio of nuclear transparencies for the e+e- channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that reported by the CBELSA-TAPS experiment and cannot be explained by recent theoretical models.

Avoidance conditioning with shock contingent upon the avoidance response

Rats learned either a lever-press response, a shuttle response or a one-way crossing response, which produced one immediate shock but was instrumental in avoiding five identical shocks scheduled to occur later. These responses were acquired both with and without support of an escape contingency. These results support shock-frequency reduction as a sufficient condition for the acquisition and maintenance of avoidance.

Methods involving light variation for isolation of cyanobacteria: characterization of isolates from central australia

We report the isolation of organisms belonging to a range of cyanobacterial genera from the remote arid region of central Australia, together with a preliminary characterization of their temporal modes of nitrogen fixation. We rendered unialgal Dermocarpa and Myxosarcina spp. (Section II organisms), LPP group B: type X (Section III), and Scytonema and Nostoc spp. (Section IV). We developed an isolation procedure based on a combination of published methods and applicable to a broad spectrum of cyanobacterial genera. We found light intensity to be a critical variable in our methodology; it was also an important determinant of the proportions of different organisms growing in stable mixtures.

Effects of Ammonium Ions, Oxygen, Carbon Monoxide, and Acetylene on Anaerobic and Aerobic Hydrogen Formation by Anabaena cylindrica B629

An investigation was made of various factors, both experimental and physiological, which influenced the formation of hydrogen gas by the heterocystous cyanobacterium Anabaena cylindrica B629 when incubated in both argon and air. A. cylindrica B629 produces hydrogen in air in the presence of carbon monoxide, acetylene, or both, with a short lag period. The rate of production in air at optimal concentrations of these compounds was found to be comparable with that in an argon atmosphere. Whereas under argon, ammonium ions (0.5 to 6 mM) were found to inhibit hydrogen formation in a manner which was dependent on light intensity and not relieved by oxygen (1 to 20% of gas phase), in air-carbon monoxide-acetylene, these ions (up to at least 0.5 mM) slightly stimulated hydrogen production for at least 24 h. Conclusions are drawn about short-term aerobic and anaerobic hydrogen formation by A. cylindrica B629 and the effects of ammonium ions, oxygen, carbon monoxide, and acetylene on these processes.

Dynamic microfunnel culture enhances mouse embryo development and pregnancy rates

BACKGROUND

Despite advances in in vitro manipulation of preimplantation embryos, there is still a reduction in the quality of embryos produced leading to lower pregnancy rates compared with embryos produced in vivo. We hypothesized that a dynamic microfunnel embryo culture system would enhance outcomes by better mimicking the fluid-mechanical and biochemical stimulation embryos experience in vivo from ciliary currents and oviductal contractions.

METHODS AND RESULTS

Mouse embryos were cultured in microdrop-static control, microfunnel-static control or microfunnel-dynamic conditions with microfluidics. All groups tested had greater than 90% total blastocyst development from zygotes after 96 h culture. Blastocyst developmental stage was significantly enhanced (P < 0.01) under dynamic microfunnel culture conditions as evidenced by an increased percentage of hatching or hatched blastocysts (Microdrop-control 31%; Microfunnel-control 23%; Microfunnel-pulsatile 71%) and significantly higher (P < 0.01) average number of cells per blastocyst (Microdrop-control 67 +/- 3; Microfunnel-control 60 +/- 3; Microfunnel-pulsatile 109 +/- 5). Blastocyst cell numbers in dynamic microfunnel cultures (109 +/- 5) more closely matched numbers obtained from in vivo grown blastocysts (144 +/- 9). Importantly, dynamic microfunnel culture significantly improved embryo implantation and ongoing pregnancy rates over static culture to levels approaching that of in utero derived preimplantation embryos.

CONCLUSIONS

The improved pregnancy outcomes along with the simple and user-friendly design of the microfluidic/microfunnel system has potential to alleviate many inefficiencies in embryo production for biomedical research, genetic gain in domestic species and assisted reproductive technologies in humans.

Protein profile of the luteal phase endometrium by tissue microarray assessment

To investigate the luteal phase endometrial expression of leukemia inhibitor factor (LIF), insulin-like growth factor 1 (IGF-1), progesterone receptor (PR), claudin 4 (CLDN4), vascular-endothelial growth factor receptor 3 (VEGFR-3), bone morphogenetic protein 4 (BMP-4) and citokeratin 7 (CK-7), we obtained luteal phase endometrial samples from 52 women. Samples were dated and integrated using a tissue microarray (TMA). Samples were immunostained for LIF, IGF-1, PR, CLDN4, VEGFR-3, BMP-4 and CK-7. Frequencies of positive expressions at the early, mid and late luteal phases were compared by two proportions test. Concomitant expression of these proteins was assessed with Chi-square or Fischer's test. The frequency of LIF was positively correlated to the frequency of IGF-1 (r = 0.99; p < 0.05) and PR (r = 0.99; p < 0.05), and the correlation between IGF-1 and PR tended to be significant (r = 0.98; p < 0.1). The expression of PR was associated with the absence of CLDN4 (p < 0.001). Thus, expression of LIF, IGF-1 and PR are correlated during the luteal phase, and immunohistochemistry for these proteins might be used to assist in the assessment of endometrial maturation. In addition, the expression of CLDN4 and PR was not concomitant, warranting further investigation on the relationship of their endometrial expression.

Microfluidic culture of single human embryonic stem cell colonies

We have developed a miniaturized microfluidic culture system that allows experimentation on individual human embryonic stem cell (hESC) colonies in dynamic (flow applied) or static (without flow) conditions. The system consists of three inlet channels that converge into a cell-culture channel and provides the capability to spatially and temporally deliver specific treatments by using patterned laminar fluid flow to different parts of a single hESC colony. We show that microfluidic culture for 96 h with or without flow results in similar maintenance of hESC self-renewal, the capability to differentiate into three germ cell lineages, and to maintain a normal karyotype, as in standard culture dishes. Localized delivery of a fluorescent nucleic acid dye was achieved with laminar flow, producing staining only in nuclei of exposed cells. Likewise, cells in desired regions of colonies could be removed with enzymatic treatment and collected for analysis. Re-coating the enzyme treated area of the channel with extracellular matrix led to re-growth of hESC colonies into this region. Our study demonstrates the culture of hESCs in a microfluidic device that can deliver specific treatments to desired regions of a single colony. This miniaturized culture system allows in situ treatment and analysis with the ability to obtain cell samples from part of a colony without micromanipulation and to perform sensitive molecular analysis while permitting further growth of the hESC colony.

The association between mother and child MTHFR C677T polymorphisms, dietary folate intake and childhood atopy in a population-based, longitudinal birth cohort

BACKGROUND

A recent study suggested a link between folate metabolism and atopy, based on a positive association between a common polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene and allergic sensitization in Danish adults.

OBJECTIVE

We investigated the associations between MTHFR C677T and allergy or atopy in a large, population-based birth cohort of children and their mothers, the Avon Longitudinal Study of Parents and Children (ALSPAC). We also looked for evidence of a pre-natal effect of maternal folate metabolism on subsequent atopic disease in the offspring.

METHODS

Mothers were recruited in pregnancy and the children followed from birth. Atopy in the child was assessed at 7-8 years of age by skin prick tests to common allergens. Asthma was defined as a physician diagnosis and current symptoms at 71/2 years of age. Asthma and allergy status of the mothers were obtained from self-completion questionnaires.

RESULTS

Data on MTHFR C677T genotype and allergy were available for 5364 children and on allergy and/or asthma for 7356 mothers. In children, the prevalence of atopy was 20.0% and asthma 10.0% whereas in mothers, the prevalence of self-reported allergy was 42.7% and asthma 11.5%. Atopy in the child was associated with male gender (P<0.001), less tobacco smoke exposure and higher maternal education. MTHFR C677T genotype was not associated with social factors or dietary folate intake. We found no evidence of associations between the MTHFR C677T variant allele and atopy, allergy or asthma in mothers or children. There was no evidence to support an effect of maternal MTHFR C677T genotype on atopy in the offspring.

CONCLUSION

The results of this study do not support the hypothesis that impaired folate metabolism is associated with allergy in adults or children in this population.

Detection of epidermal growth factor receptor gene mutations in cytology specimens from patients with non-small cell lung cancer utilising high-resolution melting amplicon analysis

Background:

Activating epidermal growth factor receptor (EGFR) mutations have been implicated in non-small cell lung cancer (NSCLC), and have also been clinically correlated with patient sensitivity to targeted EGFR inhibitors.

Aim:

To describe a technique for determining EGFR mutation status on archival fine needle aspirate (FNA) specimens from advanced NSCLC patients.

Methods:

Eleven archival FNA slides from patients with advanced NSCLC were examined for diagnostic material to identify tumour cell-enriched regions. EGFR mutation status was determined using a slide-scrape DNA extraction protocol of selected tumour cell regions on the smear slides, followed by real time PCR and high resolution melt analysis (HRMAA) of EGFR exons 18, 19, 20, and 21, followed by sequence analysis.

Results:

All DNA samples were successfully amplified by PCR. Three adenocarcinoma patient samples contained EGFR mutations in exon 19 (L747-P753insS). One of the three had an additional exon 19 mutation (A755D).

Conclusions:

Archival cytology slides from patients with NSCLC can be used to determine EGFR mutation status by PCR, HRMAA, and sequencing. The ability to use archival cytology slides greatly increases the potential material available for molecular analysis in diagnosis and selection of patients for targeted therapeutic agents.

A bidomain threshold model of propagating calcium waves

We present a bidomain fire-diffuse-fire model that facilitates mathematical analysis of propagating waves of elevated intracellular calcium (Ca(2+)) in living cells. Modeling Ca(2+) release as a threshold process allows the explicit construction of traveling wave solutions to probe the dependence of Ca(2+) wave speed on physiologically important parameters such as the threshold for Ca(2+) release from the endoplasmic reticulum (ER) to the cytosol, the rate of Ca(2+) resequestration from the cytosol to the ER, and the total [Ca(2+)] (cytosolic plus ER). Interestingly, linear stability analysis of the bidomain fire-diffuse-fire model predicts the onset of dynamic wave instabilities leading to the emergence of Ca(2+) waves that propagate in a back-and-forth manner. Numerical simulations are used to confirm the presence of these so-called 'tango waves' and the dependence of Ca(2+) wave speed on the total [Ca(2+)].

Cardiovascular disease mortality in relation to childhood and adulthood socioeconomic markers in British South Asian men

OBJECTIVE

To study the effects of childhood and adulthood socioeconomic position (SEP) including length of education on rates of cardiovascular disease (CVD) mortality in British South Asians.

DESIGN

Cross-sectional study with ongoing mortality follow-up.

SETTING

West London Borough of Ealing, population-based study.

PATIENTS

1400 South Asian men (52% Punjabi Sikh origin) aged 40-69, first studied 1988-1990 and followed for mortality to October 2006.

MAIN OUTCOME MEASURES

Deaths due to cardiovascular disease.

RESULTS

143 men have died from CVD. Men in non-manual adult occupations were less likely to die from CVD than those in unskilled manual occupations (age-adjusted hazard ratio (HR) 0.55 (95% CI 0.35 to 0.88)). Men with 11+ years of education had reduced risk compared with those with <11 years of education (HR 0.66 (95% CI 0.47 to 0.94)). Men who had both non-manual occupations and 11+ years of education were less likely to die from CVD (15 deaths, 282 men; HR 0.39, 95% CI 0.21 to 0.73) than those who were most socially disadvantaged during childhood and adulthood (27 deaths, 187 men). These associations remained after adjustment for other markers of SEP, lifestyle and conventional risk factors. Similar, but weaker, associations were observed when paternal occupation defined childhood SEP.

CONCLUSIONS

Years of education, and to a lesser extent paternal occupation, as markers of childhood SEP, had cumulative effects with adulthood socioeconomic circumstances on risk of CVD death; these cumulative effects were strongest in men whose own occupation was non-manual and were unexplained by conventional risk factors measured in middle age.

Gamete and embryo isolation and culture with microfluidics

Assisted reproductive technologies (ARTs) encompass some of the most exciting modern scientific developments that tremendously impacts society at many levels. Since the beginning of ARTs, scientists have studied and critically analyzed techniques in order to find ways to improve outcomes; however, little has changed with the actual technology and equipment for embryo in vitro production (IVP). New technologic possibilities exist with the escalating advancements of microfluidic technologies. Microfluidics is based on the behavior of liquids in a microenvironment. Although a young field, substantial research demonstrates the potential of this technology in gamete and embryo isolation and culture. In this review, we briefly discuss physical principles of microfluidics and highlight previous utilization of this technology. We then present designs and outcomes for microfluidic devices utilized thus far for different steps in the IVP process: gamete isolation and processing, fertilization, and embryo culture. Finally, we discuss and speculate on future use of microfluidics for assessing embryo viability and multiparametric analysis of embryo secretions and the integration of ART stage-specific capabilities that will lead to an "IVP-lab-on-a-chip".

Reversible phosphorylation and regulation of mammalian oocyte meiotic chromatin remodeling and segregation

The mammalian oocyte is notorious for high rates of chromosomal abnormalities. This results in subsequent embryonic aneuploidy, resulting in infertility and congenital defects. Therefore, understanding regulatory mechanisms involved in chromatin remodeling and chromosome segregation during oocyte meiotic maturation is imperative to fully understand the complex process and establish potential therapies. This review will focus on major events occurring during oocyte meiosis, critical to ensure proper cellular ploidy. Mechanistic and cellular events such as chromosome condensation, meiotic spindle formation, as well as cohesion of homologues and sister chromatids will be discussed, focusing on the role of reversible phosphorylation in control of these processes.

Li+ Transport in Lithium Sulfonylimide−Oligo(ethylene oxide) Ionic Liquids and Oligo(ethylene oxide) Doped with LiTFSI

The Li+ environment and transport in an ionic liquid (IL) comprised of Li+ and an anion of bis(trifluoromethanesulfonyl)imide anion (TFSI-) tethered to oligoethylene oxide (EO) (EO(12)TFSI-/Li+) were determined and compared to those in a binary solution of the oligoethylene oxide with LiTFSI salt (EO(12)/LiTFSI) by using molecular dynamics (MD) simulations and AC conductivity measurements. The latter revealed that the AC conductivity is 1 to 2 orders of magnitude less in the IL compared to the oligoether/salt binary electrolyte with greater differences being observed at lower temperatures. The conductivity of these electrolytes was accurately predicted by MD simulations, which were used in conjunction with a microscopic model to determine mechanisms of Li+ transport. It was discerned that structure-diffusion of the Li+ cation in the binary electrolyte (EO(12)/LiTFSI-) was similar to that in EO(12)TFSI-/Li+ IL at high temperature (>363 K), thus, one can estimate conductivity of IL at this temperature range if one knows the structure-diffusion of Li+ in the binary electrolyte. However, the rate of structure-diffusion of Li+ in IL was found to slow more dramatically with decreasing temperature than in the binary electrolyte. Lithium motion together with EO(12) solvent accounted for 90% of Li+ transport in EO(12)/LiTFSI-, while the Li+ motion together with the EO(12)TFSI- anion contributed approximately half to the total Li+ transport but did not contribute to the charge transport in IL.

Glass transition in 1,4-polybutadiene: Mode-coupling theory analysis of molecular dynamics simulations using a chemically realistic model

We present molecular dynamics simulations of the glass transition in a chemically realistic model of 1,4-polybutadiene (PBD). Around 40 K above the calorimetric glass transition of this polymer the simulations reveal a well-developed two-stage relaxation of all correlation functions. We have analyzed the time-scale separation between vibrational degrees of freedom (subpicosecond dynamics) and the alpha relaxation behavior (nanosecond to microsecond dynamics) using the predictions of mode-coupling theory (MCT). Our value for the mode-coupling critical temperature Tc agrees perfectly with prior experimental estimates for PBD. The predictions of MCT for the scaling behavior of the so-called beta relaxation, the plateau regime separating vibrational dynamics and the alpha relaxation, are well fulfilled. Furthermore, we are able to derive a consistent set of MCT exponents, completely characterizing the scaling behavior of relaxation processes in the vicinity of Tc. For the temperature dependence of the alpha relaxation we find deviations from MCT predictions which we trace to the influence of torsional barriers on the atomic motions.

Thermal desorption of hydrogen from carbon nanosheets

Carbon nanosheets are a unique nanostructure that, at their thinnest configuration, approach a single freestanding graphene sheet. Temperature desorption spectroscopy (TDS) has shown that the hydrogen adsorption and incorporation during growth of the nanosheets by radio frequency plasma-enhanced chemical vapor deposition are significant. A numerical peak fitting to the desorption spectra (300-1273 K) via the Polanyi-Wigner equation showed that desorption followed a second order process, presumably by the Langmuir-Hinshelwood mechanism. Six peaks provide the best fit to the TDS spectra. Surface desorption activation energies were determined to be 0.59, 0.63, and 0.65 eV for the external graphite surface layers and 0.85, 1.15, and 1.73 eV for desorption and diffusion from the bulk. In contrast to TDS data from previously studied a-C:H films [Schenk et al. J. Appl. Phys. 77, 2462 (1995)], a greater amount of hydrogen bound as sp(2) hybridized carbon was observed. A previous x-ray diffraction study of these films has shown a significant graphitic character with a crystallite dimension of L(a)=10.7 nm. This result is consistent with experimental results by Raman spectroscopy that show as-grown carbon nanosheets to be crystalline as commercial graphite with a crystallite size of L(a)=11 nm. Following TDS, Raman data indicate that the average crystallite increased in size to L(a)=15 nm.

Histoplasmosis infection presenting as an isolated subcutaneous periarticular upper limb swelling in the immunosuppressed patient

Atypical mycobacterial and fungal infections may occur in immunosuppressed patients. The impaired host response can make the clinical presentation atypical. Blood and tissue cultures may be negative in the acute phase of the illness, which can lead to a delay in diagnosis. In those patients with AIDS or other underlying immunosuppressive conditions, histoplasmosis cannot always be eradicated, but treatment that achieves chronic suppression may be adequate to maintain functional capacity. This report describes two immunosuppressed patients who presented with isolated subcutaneous histoplasmosis infection around the wrist.

An improvised depth gauge using a hypodermic needle

A simple solution to the problem of a broken depth gauge is suggested. A hypodermic needle is bent to simulate the shape of a depth gauge and used in a similar way. This allows measurement of the screw length against the scale on the set. We would advocate this method only when there is no suitable alternative depth gauge available.