261. Disruption of mitochondrial function in the blastocyst alters expression of the chromatin remodeler ATRX

Exposure of an embryo to suboptimal environments, including poor embryo culture media or inadequate maternal diet, can disrupt fetal and placental development and whilst the exact mechanisms responsible remain unknown, perturbed embryo metabolism has been implicated. We propose that stress applied to an early embryo causes mitochondrial dysfunction, resulting in a permanent epigenetic change. Thus the aim of this study was to determine the affect of directly perturbing mitochondria in the embryo, on development, metabolism and expression of the ATP-dependant chromatin remodelling protein, ATRX. Zygotes collected from gonadotrophin stimulated C57BL/6xCBA mice were cultured to the two-cell stage and then exposed to one of three treatments; control medium (C), medium lacking pyruvate (-P; embryos dependant on the mitochondrial Malate Aspartate Shuttle, MAS) or medium lacking pyruvate plus 5µM amino-oxyacetate (AOA), a specific MAS inhibitor (-P+AOA). Blastocyst development and metabolism were assessed by determining cell number and allocation, glycolysis, and ATP:ADP ratio. Relative gene expression of ATRX, was examined using RT PCR. Embryos dependant on the MAS alone (-P) had significantly decreased blastocyst development (87.1% v. 98.2%, P < 0.05), with a compensatory increase in glycolysis (0.20 v. 0.07 pmol/cell/hr, P < 0.001) despite a decrease in ATP:ADP (0.10 v. 0.13, P < 0.06), relative to the control. Inhibition of the MAS (-P+AOA) further reduced blastocyst development,(77.3%, P < 0.001) and decreased ATP:ADP (0.08, P < 0.004), but there was no change in glycolysis relative to control embryos (0.09 pmol/cell/hr, P = 0.3). Expression of ATRX was significantly increased for –P+AOA embryos relative to the control (1.63 v. 1.0, P < 0.007) but did not differ for –P embryos (1.1). This study demonstrates that direct perturbations of mitochondrial function in the embryo compromises its metabolic regulation and blastocyst development, and the expression of the epigenetic modulator ATRX. Further studies are underway to elucidate the implications of disrupted metabolic control and this epigenetic modulator on pregnancy outcomes.

Oxygen concentration during mouse oocyte in vitro maturation affects embryo and fetal development

BACKGROUND

Little is known of how the oxygen environment in the ovarian follicle affects oocyte and embryo development, but this has an important impact on the conditions used for in vitro maturation (IVM) of oocytes. We investigated the effect of varying oxygen concentrations during IVM on subsequent pre and post-implantation development.

METHODS

IVM of mouse cumulus-oocyte complexes (COCs) was performed under 2, 5, 10 or 20% O(2) (6% CO(2), balance N(2)). In vivo-matured COCs were collected post ovulation. Embryos were generated by IVF and culture. Blastocyst development, cell number and apoptosis were assessed, and fetal and placental outcomes analysed following embryo transfer at day 18 of pregnancy.

RESULTS

Oxygen concentration during IVM did not affect oocyte maturation or subsequent fertilization, cleavage and blastocyst development rates. Maturation of oocytes under 2% O(2) increased blastocyst trophectoderm cell number compared with all groups and numbers at 5% were higher than 20% (both P < 0.05). Percentage of apoptotic cells was increased in blastocysts developed from 2% O(2)-matured oocytes, compared with maturation at 5% O(2) or in vivo (P < 0.05). Rates of embryo implantation and development into a viable fetus were not altered by IVM oxygen. However, fetal weight was reduced following oocyte maturation at 5% O(2) compared wiht 20% O(2) and maturation at 5% O(2) also reduced placental weight, when compared with in vivo-matured oocytes (both P < 0.05).

CONCLUSIONS

Level of O(2) exposure during oocyte maturation can alter the cellular composition of blastocysts, but these changes in cell number do not correlate with the altered fetal and placental outcomes after transfer.

Metabolism of the bovine cumulus-oocyte complex and influence on subsequent developmental competence

The two types of cells that make up the cumulus-oocyte complex (i.e. the oocyte and cumulus cells) have very different metabolic demands, with glucose occupying a central role in metabolic activity. Cumulus cells have a significant requirement for and utilise high levels of glucose, yet appear to have little need for oxidative metabolism. In contrast, oocytes have a requirement for oxidative metabolism, although limited glucose metabolism may also be an important aspect of meiotic and developmental competence. Nevertheless, because of the metabolic and communication link between the cumulus and the oocyte, glucose availability and metabolism within the cumulus can have a significant impact on oocyte meiotic and developmental competence. In particular, the role of the hexosamine biosynthesis pathway within cumulus cells appears critical for the supply of substrate from glucose for extracellular matrix production, yet if overstimulated can significantly decrease developmental competence of the oocyte. Current static systems for in vitro maturation are clearly incompatible with meeting substrate demands, especially glucose. In the future, in vitro maturation will include a more dynamic approach, which will adjust nutrient components to meet the changing functional requirements of cumulus-oocyte complexes during the final process of maturation.

339 OXYGEN CONCENTRATION DURING IN VITRO MATURATION OF MURINE OOCYTES INFLUENCES SUBSEQUENT FETAL AND PLACENTAL OUTCOMES

Although the oxygen environment of the ovarian follicle is thought to influence oocyte developmental competence, little is known of the optimal oxygen environment for oocyte in vitro maturation (IVM). Previously, we found that oxygen concentration (either 2, 5, 10, or 20% O2; 6% CO2; and balance of N2) during IVM of murine oocytes had no effect on maturation rate or subsequent fertilization, cleavage, and blastocyst development rates. However, 2% O2 results in blastocysts with a higher (P &lt; 0.05) trophectoderm cell number (mean � SEM, 35.1 � 2.3) when compared to 20% (19.4 � 1.7), with 5 and 10% O2 yielding similar but intermediate cell numbers. When examined for cell apoptosis by TUNEL labelling, the 2% O2 IVM-derived embryos were also found to have a significantly higher percentage of cells undergoing apoptosis compared to the 5% O2 IVM-derived embryos and embryos derived from in vivo matured oocytes (unpublished data). Although the blastocyst development rate is not affected by varying oxygen environment during oocyte maturation, the resultant blastocysts exhibited signs of differing quality. The aim of this study was to investigate the effect of varying oxygen during IVM on post-transfer outcomes. Immature cumulus-oocyte complexes (COCs) were collected from the ovaries of eCG-stimulated CBAB6F1 females (21 days) and cultured for 17–18 h under 2, 5, or 20% O2, whereas in vivo-matured COCs were also collected post-hCG. After IVF/C (both under 5% O2), 6 blastocysts were transferred to each uterine horn of pseudopregnant Swiss recipients. Fetal and placental parameters were measured on Day 18 of pregnancy. The ability of the embryos to implant or develop was not altered by IVM oxygen concentration. However, the average weight of fetuses derived from 5% O2 matured oocytes was reduced (823.3 � 28.1 mg, P &lt; 0.05) compared to those in the 20% O2 group (928.5 � 26.1 mg). The average weight of the placenta in the 5% O2 group was also reduced (87.4 � 4.0 mg) compared to those derived from in vivo-matured oocytes (104.5 � 5.4 mg). In contrast, the fetal:placental weight ratio was unchanged in the 5% O2 treatment, suggesting these placentae, although small, are still efficient. This is the first evidence that programming of fetal/placental growth occurs from treatments applied during oocyte maturation.

A comparison of hypnotic and analgesic based sedation in a general intensive care unit †

BACKGROUND

Sedation of the critically ill patient has several components including hypnosis and analgesia. Hypnotic-based sedation (HBS), where midazolam and/or propofol are used, with morphine or another analgesic added as needed has been common. The advent of remifentanil has allowed greater use of analgesia-based sedation (ABS) where relief of discomfort from the tracheal tube or pain are the important objectives, and hypnosis is given as necessary. Method. We compared HBS and ABS (remifentanil-based sedation) within a general intensive care unit (ICU). During the first study period of 12 weeks, 111 patients received HBS. After the development of new guidelines for the use of remifentanil in the ICU, a second 12 week study period used an analgesia-based regimen, with hypnotics added only if needed.

RESULTS

Ninety-six patients received ABS, and 79 received remifentanil. It was possible to manage 29 (37%) of the patients receiving remifentanil without the use of supplementary hypnotic agents. In the remaining 63% the use of remifentanil was associated with a reduction in the amount and duration of propofol used. Significantly more patients receiving ABS had satisfactory levels of sedation during synchronized intermittent mandatory ventilation (19 [2,55] vs 50 [14,83], P<0.001).

CONCLUSIONS

The use of ABS allowed patients to be managed more comfortably, either without a hypnotic drug or with less hypnotic drug, than using conventional HBS.

Efficacy of particle-based DNA delivery for vaccination of sheep against FMDV

As an alternative strategy to classical inactivated viral vaccine against FMDV, naked DNA vaccine is attractive because of safety, flexibility and low cost. However DNA vaccination is usually poorly efficient in target species. Indeed we found that naked DNA plasmids encoding for P1-2A3C3D and GM-CSF proteins did not induce any detectable immunity against FMDV in sheep. Interestingly, we demonstrate herein that formulations of DNA on poly(D,L-lactide-co-glycolide) (PLG) or in lipofectin triggered divergent types of immune responses: PLG stimulated a T cell response and could elicit significant neutralising antibody titers, whereas lipofectin generated even higher antibody titers but no significant T cell response. The DNA/PLG regimen used in five sheep protected against clinical symptoms and viraemia and prevented the carrier state in four of them. Thus formulated DNA can be remarkably efficient against FMDV in a ruminant species that is usually refractory to DNA vaccination.

Mathematical modelling of oxygen concentration in bovine and murine cumulus–oocyte complexes

Immature oocytes benefit from nutrient modification of the follicular environment by the surrounding cumulus mass. However, the oxygen concentration that the oocyte may be exposed to could be lower than the antral follicular concentration due to the metabolism of surrounding cumulus cells. Using metabolic data previously determined, we have developed a mathematical model of O2diffusion across the bovine and murine cumulus–oocyte complex. From this we have determined that across a physiological range of external pO2, less than 0.25% and 0.5% O2is removed by cumulus cells within the bovine and murine cumulus–oocyte complex respectively. Our model differs from others as it: incorporates a term that allows for nonlinear variation of the oxygen consumption rate with oxygen concentration; considers two regions (oocyte and cumulus) sharing a common boundary, both of which consume oxygen at different non linear rates. Cumulus cells therefore remove little O2, thus sparing this essential gas for the oocyte, which is dependent on ATP generation via oxidative phosphorylation.

162 IMPROVED EMBRYO SURVIVAL AND QUALITY WITH EMCARE II

Collection of embryos exposes them to a number of stresses, including light, air, and changes in temperature. Improvement of holding media to reduce the impact of handling stresses on the embryo during in vivo collection and transfer is therefore beneficial to ensure maintenance of viability following transfer. The aim of this study was to compare the effect of holding IVP-derived blastocysts at 25°C in Emcare I (ECMI, Emcare, Dallas, TX, USA) with those held in Emcare II (ECMII), a proprietry formulation designed to reduce in vitro-induced stress. In vitro-produced bovine embryos were generated using standard protocols. Blastocysts were randomly allocated to either ECMI or ECMII (ICPBio, Aukland, New Zealand) on Day 7 and were held at 25°C for a period of 24 h, after which they were cultured in Cook Bovine Blast (Cook Australia, Brisbane, Australia) supplemented with 10% fetal calf serum for 48 h. At 24 and 48 h, embryos were scored for hatching, and a cohort removed for TUNEL staining at each time point. Differences were analyzed by Student's t-test. At both 24- and 48-h culture, hatching rates tended to be higher for embryos held in ECMII than in ECMI (Table 1). The level of apoptosis at 48 h was reduced in blastocysts held in ECMII (P = 0.06). Moreover, the total cell number of hatched blastocysts at 48 h was significantly increased (1.5-fold) in those held in ECMII (P = 0.01). Results suggest that the formulation of ECMII improves the ability of IVP bovine blastocysts to re-expand and hatch following an imposed stress (25°C for 24 h). Furthermore, ECMII improves overall embryo quality through a reduction in the percentage of cells undergoing apoptosis as well as through increased cell numbers, evident 48 h following cessation of the stress. We suggest that Emcare II reduces the impact of (or increases the embryo's tolerance to and recovery from) an imposed stress, which, although severe in the present study, may provide improved outcomes following embryo transfer in field situations. Table 1. Hatching and apoptosis of blastocysts held at 25°C for 24 h in Emcare I or Emcare II This work was supported with funding by ICPBio (NZ).

298. Dietary protein does not influence mitochondrial distribution in the 2-cell mouse embryo

Excess dietary protein can negatively influence fertility. The underlying mechanisms remain to be completely elucidated; however, variations in reproductive tract pH, and ammonium and urea concentrations have been implicated. Mouse embryos cultured in the presence of ammonium showed a shift in mitochondrial distribution away from the nucleus towards the cell cortex, suggestive of reduced mitochondrial activity, ATP production and embryo viability. In this study we determined the effect of dietary protein in vivo, on mitochondrial distribution in the 2-cell mouse embryo. Five-week-old Swiss female mice (n = 10) were fed low (9%), medium (14%) or high (25%) dietary protein for 3weeks; feed intake and body weight were recorded weekly. At 8 weeks of age mice were primed with 5 IU of PMSG, then 5 IU hCG 48 h later, and mated overnight with males of proven fertility. Forty hours post-hCG females were sacrificed, their oviducts collected and flushed with media. The total number of 2-cell embryos and oocytes retrieved were recorded. Active mitochondria were stained in the 2-cell embryos using Mitotracker Green (Molecular Probes), and were visualised using confocal microscopy. Density of perinuclear and cortical staining was determined in Photoshop 7.0, using an established method. Females fed the medium diet consumed significantly less and gained less weight than those fed the low or high diet (Table 1), despite similar final body weights (data not shown). Females fed the low diet tended to have a lower ovulation rate and fewer 2-cell embryos than females consuming the other diets (Table 1, P > 0.05). There was no significant effect of dietary protein on the distribution of mitochondria between the perinuclear and cortical region of the embryo, which may be reflective of lower in vivo ammonium levels compared to those described in culture.

265. Gonadotrophic hormones affect the uterus, implantation and fetal development in mice

Although gonadotrophin stimulation using equine chorionic gonadotrophin (eCG) adversely influences pregnancy and fetal development, the effects of stimulation using recombinant human follicle stimulating hormone (rhFSH) are largely unknown. Evidence from human studies indicates that rhFSH may also be detrimental to the endometrium and implantation. We investigated the effect of gonadotrophin stimulation on ovarian hormones and uterine characteristics in the peri-implantation period, and pregnancy outcomes in mice. Adult female mice were stimulated with 2.5 IU or 10 IU rhFSH or 5 IU eCG, followed by 5 IU human chorionic gonadotrophin (hCG). Control mice received saline injections. On day 4 of pseudopregnancy mice either had embryos transferred to the uterus or were sacrificed and blood and uterine samples collected. Plasma progesterone and estradiol concentrations were determined by radioimmunoassay. Uterine mRNA levels of the estrogen and progesterone receptors (ERa and PR), leukaemia inhibitory factor (LIF), homeobox gene Hoxa10 and vascular endothelial growth factor (VEGF) were determined by real-time RT-PCR. Uterine protein distribution of PR was determined by immunohistochemistry. Embryo transfer recipients were sacrificed on day 15 to assess pregnancy outcomes. Gonadotrophin stimulation increased plasma progesterone concentration compared to controls, while estradiol concentrations were not affected. Stimulation also reduced total LIF mRNA and altered the spatial distribution of PR protein in the uterus on day 4. Embryo transfer recipients administered eCG or 10IU rhFSH had lower pregnancy rates compared to controls (11, 35 and 75% respectively) and fetuses from the rhFSH group had reduced mean weight (94 ± 6 v. 176 ± 8 mg), length (11 ± 0.2 v. 12 ± 0.1 mm) and maturity (14.1 ± 0.09 v. 14.6 ± 0.05 days) compared to controls. These results demonstrate that gonadotrophin stimulation induces changes to the maternal reproductive tract prior to implantation that have consequences for the establishment of pregnancy and fetal development in the mouse.

233. Oxygen concentration during in vitro maturation of murine oocytes affects blastocyst cell lineage

Follicular antral oxygen tension is thought to influence subsequent oocyte developmental competence. Despite this, in vitro maturation (IVM) is routinely performed in either 5 or 20% O2 and while low O2 has been shown to be beneficial to embryo development in many species, the effect of altering O2 concentration during IVM has not been adequately investigated. Here we investigated the effects of a range of O2 concentrations during IVM on meiotic maturation and subsequent embryo development after IVF. Ovaries from eCG-stimulated CBA F1 female mice (21 days) were collected and intact cumulus oocyte complexes (COCs) cultured for 17–18 h under 2, 5, 10 or 20% O2 (6% CO2 and balance of N2). Matured COCs were denuded of cumulus cells, fixed and stained (1% aceto-orcein) for visualisation of maturation status. No significant difference in maturation rates between treatment groups was observed. Following IVF (performed under 5% O2, 6% CO2 and balance of N2), no difference in fertilisation rates between treatment groups was observed in a randomly selected cohort 7 h post-fertilisation. There was also no significant difference in cleavage rates after 24 h or ability to reach blastocyst stage after 96 h, with a tendency (P = 0.079) for more blastocysts in 2% O2. However there was a significant increase in the number of trophectoderm cells present in the resulting blastocysts (P < 0.05) in the 2% O2 group (35 ± 2.1) compared to 20% O2 (25 ± 2.8). Our data suggests that O2 concentration during IVM does not influence nuclear maturation or subsequent fertilisation, cleavage and blastocyst development rates. However, maturation in 2% O2 significantly alters subsequent cell lineage within blastocysts to favour trophectoderm development. Such skewed trophectoderm cell number may influence embryo viability. Funded by NHMRC and NIH.

027. In vitro growth and maturation: how does this technology fit for clinical application?

Superovulation protocols used in IVF result in multiple eggs that can be fertilized and grown in the laboratory to allow for selection of the best embryo for return to the mother, thereby increasing the chances for a successful pregnancy. However, there are many side effects of these superovulation drug protocols, such as deep vein thrombosis and hyperstimulation. The latter is of particular concern for women with polycystic ovary syndrome. Furthermore, the use of gonadotrophins has been reported to compromise both oocyte quality and the uterine environment and may contribute to the low success rates of IVF. Therefore the ability to collect large numbers of oocytes from women and mature them in vitro is an attractive alternative. However, although there are reports in the literature on extended maturation/culture periods of human oocytes the pregnancy rates are significantly lower than that observed after in vivo maturation. The ability to offer such technology is currently limited by the lack of understanding of how the conditions for in vitro maturation affect the quality of the oocyte and the resulting embryo. Our research is concentrated on establishing the role of metabolic balance in the oocyte for the maintenance of subsequent viability. We have determined that disruptions to the balance between mitochondrial and cytoplasmic metabolism in animal oocytes have significant adverse consequences for the resultant embryo. Changing conditions for in vitro maturation were also found to alter the establishment of the metabolic settings of the oocyte. The ability to determine the role of such parameters in maturing human oocytes will be important for the prospect of adoption of this technology for routine clinical practice.

257. Addition of glycine to vitrification solutions protects oocyte and embryo physiology and health

Cryopreservation procedures for oocytes result in a significant reduction in viability. Although cryopreservation procedures cause dehydration and therefore osmotic stress, the role of osmolytes in solutions has not been considered and they have therefore not been included for routine use. The aim of this study was to assess the effects of the addition of the osmolyte glycine to vitrification solutions on the health and developmental competence of mouse oocytes. Oocytes were collected from F1 female mice and cryopreserved using cryoloop vitrification with or without glycine, with fresh oocytes examined as controls (n = 2086). Mitochondrial distribution and membrane potential as well as the morphology of the spindles and chromosomes were assessed. Oocytes were fertilised to assess their ability to develop into blastocysts, which were then assessed for their expression of Glut1, Glut3 and IGF2 by real-time RT-PCR. Statistical analysis was performed using a generalised linear model followed by multiple comparisons using an LSD test. Vitrification without glycine perturbed mitochondrial distribution (mean pixel intensity of outer region:inner region, 1.58±0.20, P<0.01) and mitochondrial membrane potential (mean pixel intensity 0.56±0.01, P<0.01) compared to control oocytes (2.34±0.24 and 0.52±0.01, respectively). The addition of glycine prevented these changes (1.97±0.16 and 0.53±0.01, respectively). Vitrification without glycine resulted in 52% of spindles and chromosomes appearing normal while this was increased to 69% with the addition of glycine, however in both treatments these abnormalities appeared to recover after culture for 2 h. Vitrification did not affect fertilisation and blastocyst development however expression of Glut3 was decreased 2.9 fold in blastocysts resulting from oocytes vitrified in the absence of glycine (P<0.01). The data presented suggests that the addition of glycine results in fewer perturbations in oocyte physiology and gene expression of the subsequent blastocysts and should therefore be considered for routine inclusion in solutions for the cryopreservation of oocytes.

299. Sensitivity of embryos to an environmental stressor, ammonium, is dependent on stage of temporal exposure

Extended embryo culture in vitro may cause increased cellular perturbations resulting in poorer developmental outcomes. Exposure of embryos to ammonium throughout the entire pre-implantation period decreased cell number and ICM development, increased apoptosis and perturbs glucose metabolism. The aim of this study was to examine the relative susceptibility of the pre- and post-compaction stage embryo to these perturbations resulting from temporal exposure to ammonium. Mouse embryos (n = 350 per treatment) were collected from F1 female mice. Embryos were exposed to either control medium or medium with 300 μM ammonium for the entire culture period. Temporal treatments involved culture with or without ammonium, from the zygote to 2-cell stage, 2-cell to 8-cell stage, or the 8-cell to the blastocyst stage. At the blastocyst stage, ICM development, apoptosis, gene expression and glucose metabolism were assessed. Differences between treatments were determined using generalised linear modelling and LSD post-hoc tests. Exposure to ammonium at any stage did not affect blastocyst development. Exposure to ammonium pre-compaction significantly decreased both blastocyst and ICM cell number while these were unaffected when exposure occurred post-compaction. Levels of apoptosis were significantly increased when exposure to ammonium was continual to the blastocyst stage (6.5% compared to control 2.4%, P < 0.05) or from the zygote to the 2-cell stage (5.8%, P < 0.05). However, apoptosis was not altered during post-compaction exposure (2.8%). Glucose uptake was decreased by culture with ammonium at all stages of development (P < 0.001). Gene expression of GLUT1 in the blastocyst was not altered by ammonium while GLUT3 expression was significantly reduced by exposure at all stages of development (P < 0.01). The data presented suggests that the pre-compaction stage embryo is most susceptible to ammonium stress and the effects of this early stage exposure appear irreversible. Intriguingly, glucose uptake and GLUT3 expression at the blastocyst stage appear to be markers of ammonium exposure.

260. Effects of diet-induced obesity on ovarian function and female fertility

Obesity and its related complications (metabolic syndrome, Type II diabetes and polycystic ovary syndrome) are increasingly associated with female infertility. Our research is focused on understanding how diet-induced obesity, which triggers insulin resistance and symptoms of chronic inflammation, directly impacts ovarian function and female fertility. Female mice were maintained on a “Western style” diet (22% fat, 0.15% cholesterol) or a matched control diet. Body weights were monitored weekly and after 16 weeks fasting insulin levels and glucose tolerance were assessed. Mice were then paired with males and tissues collected on day 1 on pregnancy. Blood samples were taken to determine levels of progesterone, metabolites (glucose, HDL/LDL) and inflammatory cytokines. Tissue weights (fat pads, liver, kidney, spleen, pancreas, ovary and uterus) were recorded and the reproductive tissues were fixed for analysis of histology and gene expression. Zygotes were isolated from the oviduct, cultured in vitro and scored for on-time development and differentially stained to assess blastocyst quality. Indices of ovarian function, including ovulation rate, steroid production and oocyte quality/blastocyst development will then be correlated with degrees of insulin resistance, dyslipidemia and inflammation. Five strains of mice were tested (CBA, Balb/c, C57, SV129 and Swiss) and showed significant differences in susceptibility to diet-induced obesity and insulin resistance. In CBA mice, the first group to be completed, the high fat diet significantly increased body weight, but did not result in overtly impaired glucose tolerance. The number of days to mating was slightly extended compared to mice on the control diet. Interestingly, the high fat diet did not affect ovulation rate but resulted in dramatically impaired blastocyst development. The results of this study will reveal how ovarian folliculogenesis, oocyte competence and ovulation are affected by obesity-induced metabolic changes, which are increasingly affecting women of reproductive age.

235. Abberant murine embryonic development following glucosamine exposure during IVM or embryo culture

The hexosamine biosynthesis pathway is an alternate fate for glucose metabolism providing glycosylation moieties and is significantly upregulated by addition of glucosamine, a common dietary supplement. Here we determined the impact of glucosamine addition to cumulus oocyte complex (COC) maturation or during embryo culture on subsequent embryonic development. COCs were collected from 23-day-old mice 46 h post-eCG, and matured under several conditions prior to being fertilized and cultured: (1) 10mL/COC a MEM (5.56mM glucose) + 0, 1.25 or 5mM glucosamine; (2) 10mL/COC a MEM (20mM glucose) + 0, 1.25 or 5mM glucosamine; (3) 100mL/COC G2.3 (5mM glucose) + 0, 1.25 or 2.5mM glucosamine. One-cell embryos were also flushed from age-matched donors 24 h after mating and cultured in 0, 1.25 or 2.5mM glucosamine in G 1.3/2.3 sequential media. No differences in rates of embryonic development were detected between COCs matured in 10mL of media with 5.56mM glucose with glucosamine. However, blastocyst formation was significantly impaired (P<0.001) when COC maturation occurred in equivalent volumes of media that contained 20mM glucose + 1.25mM (49.98%) or 5mM glucosamine (44.7%) v. control (86.55%). Intriguingly, embryonic viability was significantly (P<0.001) reduced in COCs matured in 100mL G2.3 containing 5mM glucose + 1.25mM (44.6%) or 2.5mM glucosamine (40.1%) v. control (79.81%), suggesting a volume × glucose concentration interaction. In contrast, embryonic development was significantly reduced (34%, P < 0.002) and completely ablated when 1-cell embryos were cultured in media containing 1.25mM and 2.5mM glucosamine, respectively (control = 88.57%). These results suggest that glucosamine up-regulated hexosamine pathway activity in both COCs and early embryos impairs subsequent embryonic development by as yet undescribed mechanisms. Funded by NIH and NHMRC

The growth profile, thermotolerance and biofilm formation of Enterobacter sakazakii grown in infant formula milk

AIMS

To study the growth, thermotolerance and biofilm formation of the emergent pathogen Enterobacter sakazakii in infant formula milk (IFM).

METHODS AND RESULTS

The temperature range, death kinetics and biofilm formation of E. sakazakii were determined using impedance microbiology and conventional methods. In IFM the organism grew as low as 6 degrees C and optimally at 37-43 degrees C. In faecal coliform tests, 23% of strains (n = 70) produced gas from lauryl sulphate broth (LSB) at 44 degrees C after 48 h incubation. Three strains failed to grow in LSB at any of the temperatures. The D-value of cells suspended in IFM was determined between 54 and 62 degrees C. The resultant z-value was 5.7 degrees C. The organism was able to adhere and grow on latex, polycarbonate, silicon and to a lesser extent stainless steel.

CONCLUSIONS

Enterobacter sakazakii was able to grow at refrigeration temperatures and on infant-feeding equipment. The thermotolerance of the organism was similar to other Enterobacteriaceae and should be killed during standard pasteurization treatment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Enterobacter sakazakii has been associated with infant meningitis through consumption of contaminated IFM. Enterobacter sakazakii is able to grow in IFM during storage at refrigeration temperatures and attach to infant-feeding equipment, which may become reservoirs of infection.

Matched study of three methods for palliation of malignant pyloroduodenal obstruction

BACKGROUND

The traditional management of pyloroduodenal obstruction is open gastrojejunostomy (OGJ). More recently laparoscopic gastrojejunostomy (LGJ) and endoscopic stenting (ES) have been introduced. The aim of this study was to evaluate the three approaches to the palliation of malignant pyloroduodenal obstruction.

METHODS

All patients who underwent surgery (open and laparoscopic) for malignant pyloroduodenal obstruction at Auckland City Hospital between 1989 and 2002 inclusive were identified from International Classification of Diseases (ICD) 10 codes and from the Otago Surgical Audit Database. Patients who had an endoscopic stent were identified from the Endoscribe database. A review of medical records was conducted and data recorded in a structured pro forma. There were 181 patients with malignant pyloroduodenal obstruction of whom 56 patients had OGJ, 14 had LGJ and 16 had ES. Patients in the LGJ and ES groups were matched with those who underwent OGJ with respect to American Society of Anesthesiologists (ASA) grade (I-V), age (within 10 years) and level of obstruction (pylorus, first part of duodenum D1, D2, D3 and D4). The primary outcomes compared between the groups were time to starting free oral fluids and light diet, length of stay and survival.

RESULTS

There were no significant differences in age, sex, ASA grade and level of obstruction between the matched OGJ (n=16), LGJ (n=14) and ES (n=16) groups. There was a significant reduction in time to starting free oral fluids and light diet, and length of stay after the procedure, in the ES group. Patients who underwent surgical palliation of the obstruction had significantly more complications than those who underwent stenting (P=0.016). There were no significant differences in requirement for biliary drainage either before or after the procedure between the three groups. Survival was shortest in the ES group.

CONCLUSION

This matched study showed significant advantages for ES compared with OGJ and LGJ in the palliation of malignant pyloroduodenal obstruction.

136HIGH PROTEIN DIET INHIBITS INNER CELL MASS FORMATION AND INCREASES APOPTOSIS IN MOUSE BLASTOCYSTS DEVELOPED IN VIVO BY INCREASING THE LEVELS OF AMMONIUM IN THE REPRODUCTIVE TRACT

Ammonium is known to adversely affect the development of mouse embryos in culture. Specifically, ammonium has been found to impair inner cell (ICM) mass formation, increase apoptosis, retard fetal development following embryo transfer and induce exencephaly. Significantly, high protein diets in cattle lead to reduced fecundity. This has been linked to elevated urea levels within fluid of the female tract. In this study we have determined the effects of a high protein diet for mice on the levels of ammonium within the female tract and the effects of such a diet on the development and viability of blastocysts developed in vivo. Outbred mice (CF1) were fed a diet of either 25% (high protein) or 14% (control) protein for 4 weeks. Females were superovulated and mated to males of the same strain. In 24 mice, oviduct fluid was collected at 22h post hCG. Ammonium in the oviduct fluid was then quantitated fluorometrically. From other animals, blastocysts were flushed 92h post hCG and analyzed. Blastocyst differentiation and apoptotic indices were determined. Values are mean±SEM. Data were analysed using Student’s t-test. The levels of ammonium in the oviduct were significantly higher (P&lt;0.01) in females fed the high protein diet (356±43μM) compared to the control (68±13μM) (n=12 in each group). Blastocysts (n=139) from females fed the high protein diet had significantly lower total (43.4±1.1; P&lt;0.05) and ICM cell numbers (12.7±0.4; P&lt;0.01), compared to the control group (46.8±0.9 and 15.4±0.4 respectively; n=124). Furthermore, blastocysts from animals fed a high protein diet had a significantly higher apoptotic index (8.7±1.4; P&lt;0.01) compared to the control group (2.0±0.5). These data show that consumption of a high protein diet results in the excess accumulation of ammonium in the fluid of the female reproductive tract of mice. These high levels of ammonium subsequently impair the formation of the fetal progenitor cells and increase cell death at the blastocyst stage. These data from in vivo-developed mouse blastocysts are similar to those for blastocysts developed in culture in the presence of 300μM ammonium. Therefore, it is not advisable to maintain mice on a high protein diet. These data have significant implications for animal breeding, and for patients attempting IVF treatment.

233.Ammonium affects mitochondrial distribution and function in mouse 2-cell embryos

Amino acids are key regulators of embryo function and are essential components in embryo culture media. Amino acids spontaneously breakdown and are metabolised by embryos resulting in ammonium build-up in the medium. While ammonium does not affect blastocyst development, the ability of these blastocysts to implant was reduced along with subsequent fetal growth rates. However, the mechanism for the inhibitory effect of ammonium is currently not known. It has been demonstrated in other tissues that mitochondrial bioenergetics can be disrupted by the presence of ammonium in the media which subsequently affects cellular viability. Therefore, the aim of this study was to examine the effects of ammonium on the mitochondria of mouse embryos cultured in the presence of ammonium. Mouse zygotes from superovulated females were cultured in medium G1.2 with or without 300 μM ammonium for 22 h at 37oC in 6%CO2�:�5%O2�:�89%N2. In vivo-developed 2-cell embryos were flushed from the reproductive tract and assessed immediately. At the 2-cell stage mitochondrial distribution (Mitotracker) and membrane potential (JC-1) were assessed using confocal microscopy and images were quantitated using IP Lab software package. Differences between treatments were determined using ANOVA and Bonferroni's multiple comparison procedure. Culture of zygotes to the 2-cell stage in medium G1.2 did not affect mitochondrial distribution compared to in vivo controls. However, 2-cell embryos cultured with ammonium had a decrease in their mitochondrial nuclear�:�cortical ratio (97���1 compared to 106���1; P�<�0.05) indicating that mitochondria were dispersing away from the nuclei. Culture with ammonium also significantly decreased the mitochondrial membrane potential (0.50���0.01 mean pixel intensity ratio) compared to those cultured without ammonium (0.72���0.3 mean pixel intensity ratio, P�<�0.001). The data presented demonstrates that culture for only 24�h with ammonium disrupts both mitochondrial distribution and membrane potential and supports our hypothesis that mitochondria are an early target for the inhibitory action of ammonium.

149GLUCOSE METABOLISM OF IN VITRO AND IN VIVO PRODUCED BOVINE EMBRYOS

It has been documented that higher glucose metabolism of bovine blastocysts is correlated with higher pregnancy rates following embryo transfer. The aim of this study was to determine the effect of switching embryos between in vivo and in vitro conditions on glucose metabolism. Four types of embryos were produced: Vivo-vivo: embryos were developed entirely in vivo (7.5 days); embryos were collected from superovulated cows at Day 5 following estrus, transferred to a recipient and collected again 2.5 days later to make an appropriate control. Vivo-vitro: embryos developed 5 days in vivo and then were cultured in vitro for 2.5 days. Vitro-vivo: embryos were produced in vitro using slaughterhouse oocytes and frozen semen, cultured until Day 5, and then transferred to recipients and recovered 2.5 days later. Vitro-vitro: embryos were produced entirely in vitro up to Day 7.5. Embryos were cultured in a chemically defined, sequential system (G1/G2), using recombinant human albumin as a protein source, supplemented with hyaluronan and citrate. At Day 7.5, glucose metabolism was measured by determining the amount of 3H2O released when individual embryos (n=111 for all groups) were placed in a 3-μL hanging drop containing 3H-glucose in a closed chamber for 3h. Embryos were graded 1 (good quality) or 2 (fair or poor). Data were analyzed by ANOVA using a 4×2 factorial design with factors group (vivo-vivo, vivo-vitro, vitro-vivo, vitro-vitro) and quality (1, 2). To validate the vivo-vivo group, 15 embryos produced in vivo (without collection and re-transfer) were analyzed for glucose metabolism, resulting in similar values. Grade 1 embryos metabolized more glucose (P&lt;0.01) than Grade 2 embryos (16.6±1.2 v. 10.7±2.5pmol/embryo/h) The vivo-vivo and vitro-vitro embryos metabolized more glucose (P&lt;0.05) than the vivo-vitro and vitro-vivo embryos (15.4±1.7 and 19.3±2.0 v. 9.0±4.5 and 10.7±1.6pmol/embryo/h, respectively). There was an interaction (P&lt;0.05) due to higher glucose metabolism of Grade 1 over Grade 2 embryos in the vitro-vivo and vitro-vitro groups, but no difference between grades for the vivo-vivo and vivo-vitro groups. We conclude that assessment for visual quality was meaningful, and that changing development conditions (vivo to vitro or vitro to vivo) appears to have a detrimental effect on glucose metabolic capabilities of bovine blasocysts lasting up to 2.5 days, and possibly on their developmental competence. Significantly, bovine blastocysts cultured in sequential media G1/G2 had equivalent glucose metabolism to those embryos developed completely in vivo.

203TIMING OF IN VITRO OOCYTE MATURATION IN SPRINGBOK (ANTIDORCAS MARSUPIALIS), BLACK WILDEBEEST (CONNECHAETES GNU), BLESBOK (DAMALISCUS DORCUS PHILLIPSI), AND REEDBUCK (REDUNCA ARUNDINUM)

With an increased need for genetic diversity within populations, assisted reproductive technology is becoming an important tool for banking semen and embryos, with the possibility of future AI or embryo transfer between distant populations. Previous research has demonstrated that the broad approach of applying bovine IVM/F/C protocols to African antelope is inefficient for embryo production. The purpose of this study was to determine the timing of oocyte maturation (to telophase or metaphase II) in vitro in springbok (Antidorcas marsupialis; n=84), black wildebeest (Connechaetes gnu; n=18), blesbok (Damaliscus dorcus phillipsi; n=9), and reedbuck (Redunca arundinum; n=1). Ovaries were collected within 4h of death from culled animals on game reserves in South Africa, placed into warm SOF-HEPES, sliced and cumulus-oocyte complexes (COCs) collected. Complexes were placed into GMat medium supplemented with 0.01UmL−1 each FSH and LH, 50ngmL−1 EGF, and 1.0% (v/v) PSA (100U penicillin mL−1, 100μg streptomycin mL−1, 0.25ng amphotercin mL−1). Oocytes were removed from medium after 16, 20, 24, 28 or 32h of maturation in 5% CO2 in air at 39°C. After removal, complexes were denuded with hyaluronidase, mounted on a slide and placed into 3:1 (ethanol:glacial acetic acid) fixative until time of analysis. Oocytes were stained with aceto-orcein, and nuclear maturation was evaluated with a phase contrast microscope. As shown in the Table 1, in springbok (n=311), the percentage of mature oocytes peaked at 28h of maturation and was not different (P&lt;0.05) from oocytes matured for 32h. Fewer springbok oocytes were mature at 16, 20 and 24h. Black Wildebeest (n=88) oocytes were mature by 24h, with no additional increase in maturation at 28 or 32h. Blesbok oocytes (n=42) were not mature at 16 or 20h, and there was no difference (P&gt;0.05) in the percentage of oocytes mature at 24 or 28h. Observational data in reedbuck (n=10) indicated that no oocytes were mature at 20 or 24h, but 25.0% were mature at 28h. The low occurrence of mature oocytes at 28h in blesbok and reedbuck suggests that additional time points should be examined later in maturation. This study demonstrates that oocytes of these species can be successfully matured in vitro, but the rate of maturation and thus the optimal time of insemination for IVF is species specific. Table 1 Timing of in vitro oocyte nuclear maturation to telophase or metaphase II in springbok, black wildebeest and blesbok