Protease Expression in the Human and Rat Cumulus Oocyte Complex (COC) During the Periovulatory Period: A Role in COC Migration.

The migratory and matrix-invading capacities of the cumulus oocyte complex (COC) have been shown to be important for the ovulatory process. In metastatic cancers, these capacities are due to increased expression of proteases, however, there is limited information on protease expression in the COCs. The present study examined COC expression of plasmins, matrix metalloproteases (MMP) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) family members in the rat and human. In the rat, hCG administration increased COC expression of Mmp2, Mmp9, Mmp13, Mmp14, Mmp16, Adamts1, and the protease inhibitors Timp1, Timp3 and Serpine1 by 8-12 hours. This ovulatory induction of proteases in vivo could be mimicked by forskolin and ampiregulin treatment of cultured rat COCs with increases observed in Mmp2, Mmp13, Mmp14, Mmp16, Mmp19, Plat, and the protease inhibitors Timp1, Timp3 and Serpine1. Comparison of expression between rat COCs and granulosa cells at the time of ovulation showed decreased Mmp9 and increased Mmp13, Mmp14, Mmp16, Adamts1, Timp1 and Timp3 expression in the COCs. In human, comparison of expression between cumulus and granulosa cells at the time of IVF retrieval showed decreased MMP1, MMP2, MMP9, and ADAMTS1, while expression of MMP16, TIMP1, and TIMP3 were increased. Treatment of expanding rat COCs with a broad spectrum MMP inhibitor, GM6001, significantly reduced the migration of cumulus cells in vitro. These data provide evidence that multiple proteases and their inhibitors are expressed in the COCs and play an important role in imparting the migratory phenotype of the COCs at the time of ovulation.

Neurotensin expression, regulation, and function during the ovulatory period in the mouse ovary†.

The luteinizing hormone (LH) surge induces paracrine mediators within the ovarian follicle that promote ovulation. The present study explores neurotensin (NTS), a neuropeptide, as a potential ovulatory mediator in the mouse ovary. Ovaries and granulosa cells (GCs) were collected from immature 23-day-old pregnant mare serum gonadotropin primed mice before (0 h) and after administration of human chorionic gonadotropin (hCG; an LH analog) across the periovulatory period (4, 8, 12, and 24 h). In response to hCG, Nts expression rapidly increased 250-fold at 4 h, remained elevated until 8 h, and decreased until 24 h. Expression of Nts receptors for Ntsr1 remained unchanged across the periovulatory period, Ntsr2 was undetectable, whereas Sort1 expression (also called Ntsr3) gradually decreased in both the ovary and GCs after hCG administration. To better understand Nts regulation, inhibitors of the LH/CG signaling pathways were utilized. Our data revealed that hCG regulated Nts expression through the protein kinase A (PKA) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways. Additionally, epidermal-like-growth factor (EGF) receptor signaling also mediated Nts induction in GCs. To elucidate the role of NTS in the ovulatory process, we used a Nts silencing approach (si-Nts) followed by RNA-sequencing (RNA-seq). RNA-seq analysis of GCs collected after hCG with or without si-Nts identified and qPCR confirmed Ell2, Rsad2, Vps37a, and Smtnl2 as genes downstream of Nts. In summary, these findings demonstrate that hCG induces Nts and that Nts expression is mediated by PKA, p38MAPK, and EGF receptor signaling pathways. Additionally, NTS regulates several novel genes that could potentially impact the ovulatory process.

Alterations of Circulating Biomarkers During Late Term Pregnancy Complications in the Horse Part II: Steroid Hormones and Alpha-Fetoprotein.

Preterm labor and/or abortion causes considerable economic impact on the equine industry. Unfortunately, few experimental models exist for the induction of various pregnancy-related complications, and therefore extrapolations are made from the experimental model for ascending placentits, although inferences may be minimal. Certain steroid hormones (progestogens, estrogens) and fetal proteins (alpha-fetoprotein; AFP) might improve the diagnostics for abnormal pregnancy, but the utility of these markers in the field is unknown. To assess this, thoroughbred mares (n = 702) were bled weekly beginning in December 2013 until parturition/abortion. Following parturition, fetal membranes were assessed histopathologically and classified as either ascending placentitis (n = 6), focal mucoid placentitis (n = 6), idiopathic abortion (n = 6) or no disease (n = 20). Weekly serum samples were analyzed for concentrations of progesterone, estradiol-17ß, and AFP. Samples were analyzed retrospectively from the week of parturition/abortion in addition to the preceding four weeks. For both ascending and focal mucoid placentitis, a significant increase in progesterone and AFP was noted, alongside a significant decrease in estradiol-17ß and the ratio of estradiol-17ß to progesterone in comparison to controls. In contrast, idiopathic abortions experienced a decrease in progesterone concentrations alongside an increase in AFP, and this was only noted in the week preceding parturition/abortion. In conclusion, spontaneous placental infection in the horse altered both endocrine and feto-secretory markers in maternal circulation, while minimal changes were noted preceding noninfectious idiopathic abortion. Additionally, this is the first study to report an alteration in steroid hormones and AFP during the disease process of focal mucoid placentitis, the etiology of which includes Nocardioform placentitis.

Changes in maternal pregnane concentrations in mares with experimentally-induced, ascending placentitis.

The objectives of this study were to compare via liquid chromatography-tandem mass spectrometry (LC-MS/MS) progesterone (P4), 5α-dihydroprogesterone (DHP), allopregnanolone, 3ß-hydroxy-5α-pregnan-20-one (3ß5P), 20α-hydroxy-5α-pregnan-3-one (20α5P), 5α-pregnan-3ß,20α-diol (ßα-diol), and 5α-pregnan-3ß,20ß-diol (ßß-diol) concentrations in plasma of mares with experimentally-induced, ascending placentitis compared to gestationally age-matched control mares. Placentitis was induced via intracervical inoculation of Streptococcus equi spp. zooepidemicus between 260 and 280 days of gestation. Placentitis mares were subdivided into those which aborted in less than eight days (n = 6; acute) and those that aborted at ≥ 8 days after inoculation (n = 9; chronic). Ten pregnant mares at similar gestational ages served as healthy controls. Pregnanes were measured for days (-8), -6, -4, -3, -2, -1, and 0 days preceding abortion in the treated mares, and for the matched days of gestation in the control mares by LC-MS/MS and by immunoassay for immunoreactive (ir) P4. In mares with chronic placentitis, concentrations of DHP and its downstream metabolites (allopregnanolone, 3ß5P, 20α5P, ßα-diol) increased at 2-8 days prior to abortion compared to control mares. Of these pregnanes, 20α5P and ßα-diol increased at eight days prior to abortion and demonstrated the largest increase (approximately 3 to 4×) in mares with chronic placentitis compared to control mares. Concentrations of P4 determined by LC-MS/MS were at or below the limit of detection (0.5 ng/mL) for control mares and did not increase significantly in mares with chronic placentitis. Immunoreactive-P4 was increased at two days prior to abortion in mares with chronic placentitis but was not different from controls in mares with acute placentitis. In mares with acute placentitis, concentrations of DHP, allopregnanolone, 3ß5P, 20α5P, and ßα-diol decreased within 0-3 days prior to abortion. In mares with chronic placentitis, the patterns of increased pregnanes metabolized by the placenta was similar to changes in maternal pregnanes noted in normal mares beyond Day 300 of gestation and likely represent the effects of fetal stress and adrenal activation on pregnane metabolism by the fetus and placenta. Decreases in these same pregnanes in mares with acute cases likely reflect extreme fetal or placental compromise.

Inhibition of 5α-reductase alters pregnane metabolism in the late pregnant mare.

In the latter half of gestation in the mare, progesterone concentrations decline to near undetectable levels while other 5α-reduced pregnanes are elevated. Of these, 5α-dihydroprogesterone and allopregnanolone have been reported to have important roles in either pregnancy maintenance or fetal quiescence. During this time, the placenta is necessary for pregnane metabolism, with the enzyme 5α-reductase being required for the conversion of progesterone to 5α-dihydroprogesterone. The objectives of this study were to assess the effects of a 5α-reductase inhibitor, dutasteride on pregnane metabolism (pregnenolone, progesterone, 5α-dihydroprogesterone, 20α-hydroxy-5α-pregnan-3-one, 5α-pregnane-3ß,20α-diol and allopregnanolone), to determine circulating dutasteride concentrations and to assess effects of dutasteride treatment on gestational parameters. Pregnant mares (n = 5) received dutasteride (0.01 mg/kg/day, IM) and control mares (n = 4) received vehicle alone from 300 to 320 days of gestation or until parturition. Concentrations of dutasteride, pregnenolone, progesterone, 5α-dihydroprogesterone, 20α-hydroxy-5α-pregnan-3-one, 5α-pregnane-3ß,20α-diol, and allopregnanolone were evaluated via liquid chromatography-tandem mass spectrometry. Samples were analyzed as both days post treatment and as days prepartum. No significant treatment effects were detected in pregnenolone, 5α-dihydroprogesterone, 20α-hydroxy-5α-pregnan-3-one, 5α-pregnane-3ß,20α-diol or allopregnanolone for either analysis; however, progesterone concentrations were increased (P < 0.05) sixfold in dutasteride-treated mares compared to control mares. Dutasteride concentrations increased in the treated mares, with a significant correlation (P < 0.05) between dutasteride concentrations and pregnenolone or progesterone concentrations. Gestational length and neonatal outcomes were not significantly altered in dutasteride-treated mares. Although 5α-reduced metabolites were unchanged, these data suggest an accumulation of precursor progesterone with inhibition of 5α-reductase, indicating the ability of dutasteride to alter progesterone metabolism.

A comparison of progesterone assays for determination of peripheral pregnane concentrations in the late pregnant mare.

During the latter half of gestation in mares, there is a complex milieu of pregnanes in peripheral blood. Progesterone concentrations are often assessed by immunoassay during late gestation as a measure of pregnancy well-being; however, interpretation of results is complicated by the numerous cross-reacting pregnanes present in high concentrations during late gestation. Further, many mares are supplemented with an exogenous progestin, altrenogest, which may also cross-react with existing assays and further confound interpretation. The objectives of this study were: 1) to compare differences in pregnane concentrations determined with four immunoassays compared to LC-MS/MS and 2) to assess cross-reactivity observed with the same immunoassays, specifically considering pregnenolone (P5), progesterone (P4), 5α-dihydroprogesterone (DHP), allopregnanolone, and altrenogest. Blood samples from four healthy mares in late gestation were evaluated by immunoassay and by LC-MS/MS. Measured immuno-reactive progesterone (ir-progesterone) concentrations differed (p < 0.0001) between immunoassays, although results were highly correlated (r = 0.85-1.0; p < 0.001). Measured ir-progesterone concentrations by immunoassay were linearly associated (r2 = 0.68-0.76; p < 0.001) with concentrations of P5, P4, DHP, and allopregnanolone determined by LC-MS/MS. There was no detectable cross-reaction of altrenogest in any immunoassay, but varying degrees of cross-reactivity was observed with other pregnanes analyzed. These data confirm ir-progesterone concentrations during late gestation vary depending upon the assay used and the cross-reactivity to other pregnanes present in late gestation, although the synthetic progestin altrenogest did not affect the results of any immunoassay tested.

Inferring Intracellular Signal Transduction Circuitry from Molecular Perturbation Experiments.

The development of network inference methodologies that accurately predict connectivity in dysregulated pathways may enable the rational selection of patient therapies. Accurately inferring an intracellular network from data remains a very challenging problem in molecular systems biology. Living cells integrate extremely robust circuits that exhibit significant heterogeneity, but still respond to external stimuli in predictable ways. This phenomenon allows us to introduce a network inference methodology that integrates measurements of protein activation from perturbation experiments. The methodology relies on logic-based networks to provide a predictive approximation of the transfer of signals in a network. The approach presented was validated in silico with a set of test networks and applied to investigate the epidermal growth factor receptor signaling of a breast epithelial cell line, MFC10A. In our analysis, we predict the potential signaling circuitry most likely responsible for the experimental readouts of several proteins in the mitogen-activated protein kinase and phosphatidylinositol-3 kinase pathways. The approach can also be used to identify additional necessary perturbation experiments to distinguish between a set of possible candidate networks.

The importance of accurately correcting for the natural abundance of stable isotopes.

The use of isotopically labeled tracer substrates is an experimental approach for measuring in vivo and in vitro intracellular metabolic dynamics. Stable isotopes that alter the mass but not the chemical behavior of a molecule are commonly used in isotope tracer studies. Because stable isotopes of some atoms naturally occur at non-negligible abundances, it is important to account for the natural abundance of these isotopes when analyzing data from isotope labeling experiments. Specifically, a distinction must be made between isotopes introduced experimentally via an isotopically labeled tracer and the isotopes naturally present at the start of an experiment. In this tutorial review, we explain the underlying theory of natural abundance correction of stable isotopes, a concept not always understood by metabolic researchers. We also provide a comparison of distinct methods for performing this correction and discuss natural abundance correction in the context of steady state 13C metabolic flux, a method increasingly used to infer intracellular metabolic flux from isotope experiments.

Adipocytes promote pancreatic cancer cell proliferation via glutamine transfer.

Adipocytes promote progression of multiple cancers, but their role in pancreatic intraepithelial neoplasia (PanIN) and ductal adenocarcinoma (PDAC) is poorly defined. Nutrient transfer is a mechanism underlying stromal cell-cancer crosstalk. We studied the role of adipocytes in regulating in vitro PanIN and PDAC cell proliferation with a focus on glutamine metabolism. Murine 3T3L1 adipocytes were used to model adipocytes. Cell lines derived from PKCY mice were used to model PanIN and PDAC. Co-culture was used to study the effect of adipocytes on PanIN and PDAC cell proliferation in response to manipulation of glutamine metabolism. Glutamine secretion was measured with a bioanalyzer. Western blotting was used to study the effect of PanIN and PDAC cells on expression of glutamine-related enzymes in adipocytes. Adipocytes promote proliferation of PanIN and PDAC cells, an effect that was amplified in nutrient-poor conditions. Adipocytes secrete glutamine and rescue PanIN and PDAC cell proliferation in the absence of glutamine, an effect that was glutamine synthetase-dependent and involved PDAC cell-induced down-regulation of glutaminase expression in adipocytes. These findings suggest glutamine transfer as a potential mechanism underlying adipocyte-induced PanIN and PDAC cell proliferation.

RhoC GTPase Is a Potent Regulator of Glutamine Metabolism and N-Acetylaspartate Production in Inflammatory Breast Cancer Cells.

Inflammatory breast cancer (IBC) is an extremely lethal cancer that rapidly metastasizes. Although the molecular attributes of IBC have been described, little is known about the underlying metabolic features of the disease. Using a variety of metabolic assays, including (13)C tracer experiments, we found that SUM149 cells, the primary in vitro model of IBC, exhibit metabolic abnormalities that distinguish them from other breast cancer cells, including elevated levels of N-acetylaspartate, a metabolite primarily associated with neuronal disorders and gliomas. Here we provide the first evidence of N-acetylaspartate in breast cancer. We also report that the oncogene RhoC, a driver of metastatic potential, modulates glutamine and N-acetylaspartate metabolism in IBC cells in vitro, revealing a novel role for RhoC as a regulator of tumor cell metabolism that extends beyond its well known role in cytoskeletal rearrangement.

Inferring the Effects of Honokiol on the Notch Signaling Pathway in SW480 Colon Cancer Cells.

In a tumor cell, the development of acquired therapeutic resistance and the ability to survive in extracellular environments that differ from the primary site are the result of molecular adaptations in potentially highly plastic molecular networks. The accurate prediction of intracellular networks in a tumor remains a difficult problem in cancer informatics. In order to make truly rational patient-driven therapeutic decisions, it will be critical to develop methodologies that can accurately infer the molecular circuitry in the cells of a specific tumor. Despite enormous heterogeneity, cellular networks elicit deterministic digital-like responses. We discuss the use and limitations of methodologies that model molecular networks in cancer cells as a digital circuit. We also develop a network model of Notch signaling in colon cancer using a novel reverse engineering logic-based method and published western blot data to elucidate the interactions likely present in the circuits of the SW480 colon cancer cell line. Within this framework, we make predictions related to the role that honokiol may be playing as an anti-cancer drug.

Follow-the-leader cell migration requires biased cell-cell contact and local microenvironmental signals.

Directed cell migration often involves at least two types of cell motility that include multicellular streaming and chain migration. However, what is unclear is how cell contact dynamics and the distinct microenvironments through which cells travel influence the selection of one migratory mode or the other. The embryonic and highly invasive neural crest (NC) are an excellent model system to study this question since NC cells have been observed in vivo to display both of these types of cell motility. Here, we present data from tissue transplantation experiments in chick and in silico modeling that test our hypothesis that cell contact dynamics with each other and the microenvironment promote and sustain either multicellular stream or chain migration. We show that when premigratory cranial NC cells (at the pre-otic level) are transplanted into a more caudal region in the head (at the post-otic level), cells alter their characteristic stream behavior and migrate in chains. Similarly, post-otic NC cells migrate in streams after transplantation into the pre-otic hindbrain, suggesting that local microenvironmental signals dictate the mode of NC cell migration. Simulations of an agent-based model (ABM) that integrates the NC cell behavioral data predict that chain migration critically depends on the interplay of biased cell-cell contact and local microenvironment signals. Together, this integrated modeling and experimental approach suggests new experiments and offers a powerful tool to examine mechanisms that underlie complex cell migration patterns.

Logic-based models in systems biology: a predictive and parameter-free network analysis method.

Highly complex molecular networks, which play fundamental roles in almost all cellular processes, are known to be dysregulated in a number of diseases, most notably in cancer. As a consequence, there is a critical need to develop practical methodologies for constructing and analysing molecular networks at a systems level. Mathematical models built with continuous differential equations are an ideal methodology because they can provide a detailed picture of a network's dynamics. To be predictive, however, differential equation models require that numerous parameters be known a priori and this information is almost never available. An alternative dynamical approach is the use of discrete logic-based models that can provide a good approximation of the qualitative behaviour of a biochemical system without the burden of a large parameter space. Despite their advantages, there remains significant resistance to the use of logic-based models in biology. Here, we address some common concerns and provide a brief tutorial on the use of logic-based models, which we motivate with biological examples.

Computational modelling of cell chain migration reveals mechanisms that sustain follow-the-leader behaviour.

Follow-the-leader chain migration is a striking cell migratory behaviour observed during vertebrate development, adult neurogenesis and cancer metastasis. Although cell-cell contact and extracellular matrix (ECM) cues have been proposed to promote this phenomenon, mechanisms that underlie chain migration persistence remain unclear. Here, we developed a quantitative agent-based modelling framework to test mechanistic hypotheses of chain migration persistence. We defined chain migration and its persistence based on evidence from the highly migratory neural crest model system, where cells within a chain extend and retract filopodia in short-lived cell contacts and move together as a collective. In our agent-based simulations, we began with a set of agents arranged as a chain and systematically probed the influence of model parameters to identify factors critical to the maintenance of the chain migration pattern. We discovered that chain migration persistence requires a high degree of directional bias in both lead and follower cells towards the target. Chain migration persistence was also promoted when lead cells maintained cell contact with followers, but not vice-versa. Finally, providing a path of least resistance in the ECM was not sufficient alone to drive chain persistence. Our results indicate that chain migration persistence depends on the interplay of directional cell movement and biased cell-cell contact.

Unraveling the complex regulatory relationships between metabolism and signal transduction in cancer.

Cancer cells exhibit an altered metabolic phenotype, known as the Warburg effect, which is characterized by high rates of glucose uptake and glycolysis, even under aerobic conditions. The Warburg effect appears to be an intrinsic component of most cancers and there is evidence linking cancer progression to mutations, translocations, and alternative splicing of genes that directly code for or have downstream effects on key metabolic enzymes. Many of the same signaling pathways are routinely dysregulated in cancer and a number of important oncogenic signaling pathways play important regulatory roles in central carbon metabolism. Unraveling the complex regulatory relationship between cancer metabolism and signaling requires the application of systems biology approaches. Here we discuss computational approaches for modeling protein signal transduction and metabolism as well as how the regulatory relationship between these two important cellular processes can be combined into hybrid models.

Kinase inhibitors can produce off-target effects and activate linked pathways by retroactivity.

BACKGROUND: It has been shown in experimental and theoretical work that covalently modified signaling cascades naturally exhibit bidirectional signal propagation via a phenomenon known as retroactivity. An important consequence of retroactivity, which arises due to enzyme sequestration in covalently modified signaling cascades, is that a downstream perturbation can produce a response in a component upstream of the perturbation without the need for explicit feedback connections. Retroactivity may, therefore, play an important role in the cellular response to a targeted therapy. Kinase inhibitors are a class of targeted therapies designed to interfere with a specific kinase molecule in a dysregulated signaling pathway. While extremely promising as anti-cancer agents, kinase inhibitors may produce undesirable off-target effects by non-specific interactions or pathway cross-talk. We hypothesize that targeted therapies such as kinase inhibitors can produce off-target effects as a consequence of retroactivity alone. RESULTS: We used a computational model and a series of simple signaling motifs to test the hypothesis. Our results indicate that within physiologically and therapeutically relevant ranges for all parameters, a targeted inhibitor can naturally induce an off-target effect via retroactivity. The kinetics governing covalent modification cycles in a signaling network were more important for propagating an upstream off-target effect in our models than the kinetics governing the targeted therapy itself. Our results also reveal the surprising and crucial result that kinase inhibitors have the capacity to turn "on" an otherwise "off" parallel cascade when two cascades share an upstream activator. CONCLUSIONS: A proper and detailed characterization of a pathway's structure is important for identifying the optimal protein to target as well as what concentration of the targeted therapy is required to modulate the pathway in a safe and effective manner. We believe our results support the position that such characterizations should consider retroactivity as a robust potential source of off-target effects induced by kinase inhibitors and other targeted therapies.

Temporal patterns of conditions and symptoms potentially associated with ovarian cancer.

BACKGROUND: The late stage at which ovarian cancer is typically diagnosed and its subsequent high mortality have been attributed to a lack of symptoms in its early stages. This study examined the temporal patterns of prediagnostic ovarian cancer symptoms and conditions among women with and without ovarian cancer. METHODS: We identified 920 ovarian cancer cases from 1998-2002 claims and encounters from Thomson Healthcare's Medstat MarketScan Commercial Claims and Encounters and Medicare Supplemental Databases. These were matched with 2760 comparison women based on age, geographic region, Medicare eligibility, and health plan type. The rates of ovarian cancer-related symptoms, conditions, and procedures recorded in the claims data were compared between the two groups using chi-square and Student's t tests. RESULTS: In the 270 to 31 days prior to the case diagnosis dates, cases had nearly five times more recorded abdominal symptoms (36.2% vs. 7.5%), 3.5 times more recorded female genital symptoms (9.8% vs. 2.7%), and 1.5-2 times more recorded gastrointestinal symptoms (7.7% vs. 3.5%), urethra/urinary tract disorders (12.7% vs. 6.4%), and menopausal disorders (12.4% vs. 7.5%) than the comparison women. However, when the data were examined in 30-day increments for these five diagnosed conditions, the rates for cases and comparison women only started to diverge as the cases' diagnosis drew closer-60-90 days prior. CONCLUSIONS: The presence of ovarian cancer-related symptoms and conditions prior to diagnosis among cases was documented in claims data; however, this increase was most pronounced in the 2-3 months prior to diagnosis. It is likely that physicians will see similar symptoms and conditions for women with and without ovarian cancer during most of the 9 months prior to the cases' diagnosis.

Predictors of comprehensive surgical treatment in patients with ovarian cancer.

BACKGROUND: Providing appropriate surgical treatment for women with ovarian cancer is one of the most effective ways to improve ovarian cancer outcomes. In this study, the authors identified factors that were associated with a measure of comprehensive surgery, so that interventions may be targeted appropriately to improve surgical care. METHODS: Using Healthcare Cost and Utilization Project hospital discharge data from 1999 to 2002 for 9 states, the authors identified 10,432 admissions of women who had an International Classification of Disease, 9th Revision (ICD-9) primary diagnosis of ovarian cancer and who had undergone oophorectomy. Based on National Institutes of Health Consensus Panel recommendations, surgeries were categorized as comprehensive by using ICD-9 diagnosis and procedure codes. Logistic regression analysis using data from 5 states with a full set of variables (n = 6854 patients)was used to identify factors that were associated with the receipt of comprehensive surgical care. RESULTS: Overall, 66.9% of admissions (range, 46.3-80.8% of admissions) received comprehensive surgery. Factors that were associated independently with comprehensive surgical care included age (ages 21-50 years vs ages 71-80 years or > or = 81 years), race (Caucasian vs African American or Hispanic), payer (private insurance vs Medicaid), cancer stage (advanced vs early), annual surgeon volume (low/medium [2-9 surgeries per year] or high [>10 surgeries per year] vs very low [1 surgery per year]), and surgeon specialty (gynecologic oncologists vs obstetrician gynecologists or general surgeons). Among nonteaching hospitals, medium-volume hospitals (10-19 ovarian cancer surgeries per year) and high-volume hospitals (> or = 20 surgeries per year) had significantly higher comprehensive surgery rates than low-volume facilities (1-9 surgeries per year). Volume did not influence comprehensive surgery rates in teaching hospitals. CONCLUSIONS: Many women with ovarian cancer, especially those in poor, elderly, or minority groups, are not receiving recommended comprehensive surgery. Efforts should be made to ensure that all women with ovarian cancer, especially those in vulnerable populations, have the opportunity to receive care from centers or surgeons with higher comprehensive surgery rates.

Modulation of epileptiform activity by glutamine and system A transport in a model of post-traumatic epilepsy.

Epileptic activity arises from an imbalance in excitatory and inhibitory synaptic transmission. To determine if alterations in the metabolism of glutamate, the primary excitatory neurotransmitter, might contribute to epilepsy we directly and indirectly modified levels of glutamine, an immediate precursor of synaptically released glutamate, in the rat neocortical undercut model of hyperexcitability and epilepsy. We show that slices from injured cortex take up glutamine more readily than control slices, and an increased expression of the system A transporters SNAT1 and SNAT2 likely underlies this difference. We also examined the effect of exogenous glutamine on evoked and spontaneous activity and found that addition of physiological concentrations of glutamine to perfusate of slices isolated from injured cortex increased the incidence and decreased the refractory period of epileptiform potentials. By contrast, exogenous glutamine increased the amplitude of evoked potentials in normal cortex, but did not induce epileptiform potentials. Addition of physiological concentrations of glutamine to perfusate of slices isolated from injured cortex greatly increased abnormal spontaneous activity in the form of events resembling spreading depression, again while having no effect on slices from normal cortex. Interestingly, similar spreading depression like events were noted in control slices at supraphysiological levels of glutamine. In the undercut cortex addition of methylaminoisobutyric acid (MeAIB), an inhibitor of the system A glutamine transporters attenuated all physiological effects of added glutamine suggesting that uptake through these transporters is required for the effect of glutamine. Our findings support a role for glutamine transport through SNAT1 and/or SNAT2 in the maintenance of abnormal activity in this in vitro model of epileptogenesis and suggest that system A transport and glutamine metabolism are potential targets for pharmacological intervention in seizures and epilepsy.