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

Recombinant human albumin supports hamster in-vitro fertilization

BACKGROUND

Serum albumin is normally required to support sperm capacitation and IVF, but its mechanism of action is not well understood. Commercial serum albumin preparations are contaminated with a variety of other proteins and compounds, and their biological activity is variable. Recombinant human albumin (rHA) might replace serum albumin for IVF.

METHODS

rHA was examined for its ability to capacitate hamster spermatozoa and to support fertilization in vitro. A standardized hamster IVF system was used to compare the capacitation-supporting activities of rHA and two commercial preparations of bovine serum albumin (BSA) in a chemically defined culture medium. Epididymal spermatozoa were incubated for 4 h at 37 degrees C under 5% CO(2) in air in either the basic medium containing rHA, one of the two BSA preparations or no protein, and then cultured in the same medium with ovulated oocytes for another 4 h. The experiment was replicated five times.

RESULTS

Spermatozoa incubated in protein-free medium fertilized only one oocyte (2% of total), significantly less than any of the other three treatment conditions (P < 0.01); spermatozoa incubated in medium containing rHA or BSA fertilized 86-93% of oocytes. There were no differences between the three albumin-containing treatment groups.

CONCLUSION

rHA is equivalent to commercial serum albumin preparations in its ability to support sperm capacitation and fertilization in this test system. This finding has considerable practical implications for human IVF and may also help efforts to elucidate the mechanism of sperm capacitation.

Serum pharmacokinetics and tissue and milk residues of oxytetracycline in goats following a single intramuscular injection of a long-acting preparation and milk residues following a single subcutaneous injection

Separate groups of goats were used to determine drug depletion patterns in serum (n=10), tissue (n=20) and milk (n=8) following a single intramuscular (i.m.) dose of 20 mg/kg of a long-acting oxytetracycline (OTC) formulation (Liquamycin LA-200). Milk residues were also determined following a subcutaneous (s.c.) administration of the same product at the same dose. Serum samples were taken for 24 h post-treatment and tissues (fat, liver, kidney, muscle and injection site) collected at 4, 7, 14, 21 and 28 days following injection. Milk from lactating goats was collected every 12 h for 8 days following both the i.m. and s.c. treatments utilizing an intervening 5-week washout period. Residues in serum and tissue were measured using a microbial inhibition assay, while milk residues were measured using both a microbial inhibition assay and a validated HPLC method. The serum pharmacokinetic parameters of OTC in goats were determined, with a mean AUC=67.4 microg h/mL, mean terminal half-life=14.4 h, and apparent clearance=0.33 L/kg h. Tissue half-lives could not be determined with confidence because the collection times provided only two points at which residues could be measured for most tissues. Oxytetracycline residues in all goat tissue samples measured less then cattle tissue tolerance by 96 h postdosing. One-compartment model describing milk depletion data for i.m. and s.c. dosing had terminal slope half-lives of 20.1 and 36.1 h, respectively. By 96 h post-treatment none of the milk samples contained OTC residues in excess of the cattle milk tolerance (0.3 p.p.m.). For both milk and tissue, the upper-bound 99% confidence intervals for the samples taken from goats 96 h postdosing were lower than approved cow milk and tissue tolerances.

Noninvasive assessment of human embryo nutrient consumption as a measure of developmental potential

OBJECTIVE

To determine the relationship between blastocyst development and morphology and embryo metabolism.

DESIGN

Noninvasive assessment of carbohydrate uptake and ammonium production by individual embryos.

SETTING

Private assisted reproductive technology unit.

PATIENT(S)

Patients donated, with consent, cryopreserved pronucleate embryos and noncryopreserved blastocysts.

INTERVENTION(S)

Culture of 60 thawed pronucleate embryos in sequential media to the blastocyst stage with concomitant noninvasive analysis of embryo metabolism and analysis of 13 blastocysts from noncryopreserved embryos.

MAIN OUTCOME MEASURE(S)

Pyruvate and glucose consumption as well as blastocyst formation and quality.

RESULT(S)

Pyruvate and glucose uptakes on day 4 were significantly higher by embryos that went on to form blastocysts than by embryos that failed to develop to the blastocyst stage. Glucose uptakes were greatest in those blastocysts of highest grade, whereas pyruvate uptakes were similar irrespective of blastocyst grade, indicating that glucose is the more important nutrient for the human blastocyst. Among blastocysts of the same grade from the same patient, there was considerable spread of glucose consumption, indicating that glucose consumption may be of use in identifying blastocysts for transfer. Ammonium production by individual embryos was also measured, reflecting amino acid transamination and use by the human embryo.

CONCLUSION(S)

The ability to identify in culture the embryo with the highest developmental potential will facilitate the move to single-embryo transfers.

Comparison of postoperative outcomes in ulcerative colitis and familial polyposis patients after ileoanal pouch operations

BACKGROUND

Pouchitis is a poorly understood inflammatory condition that occurs in the ileal pouches of patients who have undergone the ileal-pouch anal anastomosis after restorative proctocolectomy. This postoperative condition is much more common in patients with ulcerative colitis (UC) than familial adenomatous polyposis (FAP) colitis. It has been suggested that, owing to pouchitis, UC patients do not attain the same quality of life that FAP patients do after the ileal-pouch anal anastomosis operation. We hypothesized that health-related quality of life does not differ between FAP and UC patients.

METHODS

We analyzed the postoperative morbidity and gastrointestinal function in 110 consecutive patients having undergone the ileal-pouch anal anastomosis for either UC or FAP at OU Medical Center from 1983 to 2000 by retrospective record review. Health-related quality of life was assessed in 83 patients using the Short Inflammatory Bowel Disease Questionnaire (SIBDQ) and the Medical Outcome Study Short-Form 36 (SF-36) questionnaire.

RESULTS

With the exception of pouchitis, there was no difference in perioperative outcome, morbidity, or functional status between UC and FAP patients. The SIBDQ and SF-36 revealed no statistically significant difference between FAP and UC patients.

CONCLUSIONS

As expected, UC patients are more likely to develop pouchitis. Despite this, our data reveal that both patient groups enjoy a similarly good functional status and quality of life.

Inhibiting 3-phosphoglycerate kinase by EDTA stimulates the development of the cleavage stage mouse embryo

Addition of EDTA to the medium significantly enhances mouse embryo development in culture. Embryos cultured in the absence of EDTA exhibit abnormal increases in glycolytic activity that result in reduced development. Culture with EDTA was able to prevent this increase in glycolysis and, therefore, maintain developmental competence. EDTA was shown to inhibit the activity of the glycolytic enzyme, 3-phosphoglycerate kinase. Additionally, the effect of EDTA on maintaining high rates of embryo development in culture could be mimicked by the addition of Cibacron blue, an inhibitor of 3-phosphoglycerate kinase. The inhibition of 3-phosphoglycerate kinase by EDTA could be overcome by the addition of exogenous magnesium, indicating that the effect of EDTA was to reduce the availability of this co-factor to the glycolytic kinases. Embryos cultured with EDTA had significantly lower levels of intracellular magnesium compared to embryos cultured without EDTA. Therefore, the effect of EDTA appears to be as a chelator of divalent cations such as magnesium, that are required for normal activity of kinases such as 3-phosphoglycerate kinase.

Iodoacetate protects hippocampal neurons against excitotoxic and oxidative injury: involvement of heat-shock proteins and Bcl-2

Mild metabolic stress may increase resistance of neurons in the brain to subsequent, more severe insults, as demonstrated by the ability of ischemic pre-conditioning and dietary restriction to protect neurons in experimental models of stroke- and age-related neurodegenerative disorders. In the present study we employed iodoacetic acid (IAA), an inhibitor of glyceraldehyde-3-phosphate dehydrogenase, to test the hypothesis that inhibition of glycolysis can protect neurons. Pre-treatment of cultured hippocampal neurons with IAA can protect them against cell death induced by glutamate, iron and trophic factor withdrawal. Surprisingly, protection occurred with concentrations of IAA (2-200 nM) much lower than those required to inhibit glycolysis. Pre-treatment with IAA results in suppression of oxyradical production and stabilization of mitochondrial function in neurons after exposure to oxidative insults. Levels of the stress heat-shock proteins HSP70 and HSP90, and of the anti-apoptotic protein Bcl-2, were increased in neurons exposed to IAA. Our data demonstrate that IAA can stimulate cytoprotective mechanisms within neurons, and suggest the possible use of IAA and related compounds in the prevention and/or treatment of neurodegenerative conditions.