Medical Management of Endometriosis in Adolescent and Young Adult Women: A Review of 91 Cases of Biopsy-Confirmed Endometriosis.

OBJECTIVE: To characterize contemporary trends in the hormonal management of endometriosis in adolescent and young adult patients with biopsy-proven endometriosis. METHODS: Retrospective chart review of women aged 14-25 who underwent laparoscopy for pelvic pain with biopsy-proven endometriosis between January 2011 and September 2020 at an academic tertiary hospital system. Final sample included 91 patients with biopsy-confirmed endometriosis. RESULTS: Combined oral contraceptives (COCs) were the most common initial treatment (64% of patients). Progestin-only formulations (low- and high-dose norethindrone acetate) were offered to younger patients (age 15.9 ± 2.7 years) than those offered COCs (19.9 ± 3.3 years) and levonorgestrel intrauterine devices (LNG-IUDs) (21.9 ± 1.7 years). Current treatments varied widely and included COCs (32%), LNG-IUDs (18%), oral progestins (low- and high-dose norethindrone, medroxyprogesterone) (14%), elagolix (9%), and leuprolide (8%). Oral adjuncts to LNG-IUD were common: usually low- or high-dose norethindrone (37% of patients with an LNG-IUD), but also included progesterone, COCs, and elagolix. CONCLUSION: Oral progestins, LNG-IUDs, and COCs were the mainstay of initial treatment. Subsequent treatments varied widely and included COCs, LNG-IUDs, oral progestins, elagolix, leuprolide, and combinations of these agents. We observed that most young women switched between therapies, suggesting that a personalized approach is often used to determine treatment plans among the wide range of options currently available. This study helps define the spectrum of treatment regimens for endometriosis in adolescent females.

Age-related changes in Folliculogenesis and potential modifiers to improve fertility outcomes - A narrative review.

Reproductive aging is characterized by a decline in oocyte quantity and quality, which is directly associated with a decline in reproductive potential, as well as poorer reproductive success and obstetrical outcomes. As women delay childbearing, understanding the mechanisms of ovarian aging and follicular depletion have become increasingly more relevant. Age-related meiotic errors in oocytes are well established. In addition, it is also important to understand how intraovarian regulators change with aging and how certain treatments can mitigate the impact of aging. Individual studies have demonstrated that reproductive pathways involving antimullerian hormone (AMH), vascular endothelial growth factor (VEGF), neurotropins, insulin-like growth factor 1 (IGF1), and mitochondrial function are pivotal for healthy oocyte and cumulus cell development and are altered with increasing age. We provide a comprehensive review of these individual studies and explain how these factors change in oocytes, cumulus cells, and follicular fluid. We also summarize how modifiers of folliculogenesis, such as vitamin D, coenzyme Q, and dehydroepiandrosterone (DHEA) may be used to potentially overcome age-related changes and enhance fertility outcomes of aged follicles, as evidenced by human and rodent studies.

Impact of sleep patterns upon female neuroendocrinology and reproductive outcomes: a comprehensive review.

Sleep is vital to human bodily function. Growing evidence indicates that sleep deprivation, disruption, dysrhythmia, and disorders are associated with impaired reproductive function and poor clinical outcomes in women. These associations are largely mediated by molecular-genetic and hormonal pathways, which are crucial for the complex and time sensitive processes of hormone synthesis/secretion, folliculogenesis, ovulation, fertilization, implantation, and menstruation. Pathologic sleep patterns are closely linked to menstrual irregularity, polycystic ovarian syndrome, premature ovarian insufficiency, sub/infertility, and early pregnancy loss. Measures of success with assisted reproductive technology are also lower among women who engage in shift work, or experience sleep disruption or short sleep duration. Extremes of sleep duration, poor sleep quality, sleep disordered breathing, and shift work are also associated with several harmful conditions in pregnancy, including gestational diabetes and hypertensive disorders. While accumulating evidence implicates pathologic sleep patterns in impaired reproductive function and poor reproductive outcomes, additional research is needed to determine causality and propose therapeutic interventions.

Analysis of female demographics in the United States: life expectancy, education, employment, family building decisions, and fertility service utilization.

PURPOSE OF REVIEW: To discuss changes in female demographic parameters in the US and associated increase in utilization of fertility services. RECENT FINDINGS: Fractions of women earning bachelor's, master's, and doctoral degrees increased from 1970 to 2018 (32.6 vs 64.8; 7.9 vs 27.3; 0.54 vs 5.7 per 10,000 women; P < .001; respectively). This was associated with decrease in percentage of married women (61.9% vs 50.8%) and increase in median age at first marriage (20.8 vs 27.8). In parallel, mean age of mothers at first birth increased (21.4 vs 26.8), and pregnancy rates of women aged 35-39 and 40-44 years doubled between 1980 and 2010 (0.036 vs 0.077; 0.009 vs 0.019 per 1,000 women). With later pregnancy attempts, female fertility rates decreased from 1970 to 2017 (87.9% vs 60.3%; P < .001). Women undergoing assisted reproductive technologies (ART) treatment with a DOR diagnosis increased (12% vs 31%), and ART cycles using donor eggs increased (16,161 vs 24,300), between 2005 and 2016. SUMMARY: Participation of women in education is paralleled by increased female employment, later occurrence of marriage, increased age of childbearing, decreased fertility rates, and increased DOR diagnosis.

Miscarriage determination in first trimester based on alpha-fetoprotein extracted from sanitary pads.

OBJECTIVE: To determine if high alpha-fetoprotein (AFP) level in vaginal blood collected on a sanitary pad can assist with detecting an active miscarriage. DESIGN: A prospective cohort study. SETTING: Academic medical center. PATIENT(S): Five groups were evaluated: women with active miscarriage, pregnancy of unknown location, completed miscarriage or extrauterine pregnancy (EUP), ongoing pregnancy, and undergoing elective dilation and curettage (D&C). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): For each patient, AFP level in the vaginal blood collected on a sanitary pad was quantified. RESULT(S): The vaginal blood AFP median levels (and their ranges) were 3.7 IU/mL (0.5-739.2) and 4,542 IU/mL (15.6-100,000) in the active miscarriage (n = 16) and the elective D&C (n = 24) groups, respectively. Alpha-fetoprotein was detected in all elective D&C and active miscarriage cases except in 1 case. In the ongoing pregnancy group (n = 35), only 2 of 35 specimens showed detectable AFP levels. In the pregnancy of unknown location (n = 12) and the completed miscarriage or EUP (n = 10) groups, no AFP was detected. Receiver operating characteristic analysis demonstrated 93.7% sensitivity and 97.8% specificity for the detection of an active miscarriage (cutoff 0.61 IU/mL; area under the curve 0.96). CONCLUSION(S): Alpha-fetoprotein can be extracted from vaginal blood collected on sanitary pads. A high level of vaginal AFP can assist with the same-day detection of an active miscarriage. This novel test is useful in differentiating active miscarriages from ongoing pregnancies, completed miscarriages, and EUPs and, therefore, it reduces uncertainty, anxiety level, and number of repeat office visits.

Mitochondrial Stress Response Gene Clpp Is Not Required for Granulosa Cell Function.

Mitochondrial unfolded protein response (UPRmt) is a highly conserved mechanism, which is activated upon cellular or metabolic stress and aims to help cells maintain homeostasis. CLPP (caseinolytic peptidase P) plays a crucial factor for UPRmt; it promotes the degradation of unfolded mitochondrial proteins. Global germline deletion of Clpp in mice results in female infertility and accelerated follicular depletion. Here, we asked whether CLPP is necessary for granulosa/cumulus cell function. Clppflox/flox mice were generated and crossbred with Cyp19a1-Cre mice to generate mice with granulosa/cumulus cell-specific Clpp deletion (Clpp-/-). Mature (8-week-old) Clpp-/- female mice (8-week-old) were compared to same age wild type (WT) mice. We found that mature Clpp-/- female mice were fertile and produced a similar number of pups per litter compared to WT. Folliculogenesis was not affected by the loss of CLPP in granulosa/cumulus cells as Clpp-/- and WT mice had a similar number of primordial, primary, secondary, early antral, and antral follicles. The number of germinal vesicles (GV) and MII oocytes collected from Clpp-/- and WT female mice were also similar. Our findings demonstrate that fertility in female mice is not affected by granulosa/cumulus cell-specific UPRmt disruption through CLPP deletion.

A step towards the automation of intracytoplasmic sperm injection: real time confirmation of mouse and human oocyte penetration and viability by electrical resistance measurement.

OBJECTIVE: To evaluate if oocyte penetration and viability can be confirmed by an electrical resistance increase. Automated (robotic) intracytoplasmic sperm injection (ICSI) requires confirmation of oolemma penetration before sperm injection. Visual assessment using image processing algorithms have been developed but remain unreliable. We hypothesized that an increase in electrical resistance upon oolemma piercing during ICSI can serve as an objective tool to confirm oocyte penetration and viability. DESIGN: Experimental study. SETTING: Research laboratory in an academic center. PATIENTS/ANIMALS: Oocytes from female mice and women undergoing oocyte retrieval procedure. INTERVENTION: Oolemma piercing attempts with the ICSI pipette were performed by advancing the pipette towards mature (metaphase II) oocytes collected from 6 to 12-week-old mice and immature (germinal vesicle stage and metaphase I) oocytes donated by women who underwent oocyte retrieval. Electrical resistance was measured using a conventional electrophysiological setup that includes an electrical resistance meter and two electrical wires located in the lumina of the holding and ICSI pipettes. MAIN OUTCOME MEASURE(S): The measure of interest was the change in electrical resistance (ΔR) before and after advancing the ICSI pipette in an attempt to penetrate an oocyte. The experiments of resistance measurements were done in 3 steps: Step 1 (proof of concept), penetrated vs. non-penetrated mouse oocytes. Step 2, mouse oocytes with visually intact oolemma vs. fragmented mouse oocytes. Step 3, human oocytes with visually intact oolemma vs. fragmented human oocytes. For each group, median and range (in parenthesis) of ΔR were determined in MΩ. Mann-Whitney test was performed to compare the two groups in each step. RESULTS: In Step 1, the penetrated mouse oocytes showed a statistically significant resistance increase compared to the non-penetrated ones (n = 20, median ΔR = 7.79 [2.57 - 106.00] vs. n = 15, median ΔR = 0.10 [-0.06 - 0.69], respectively. In Step 2, the mouse oocytes with visually intact oolemma showed a statistically significant resistance increase compared to the fragmented ones (n = 45, median ΔR = 6.5 [0.1 - 191.7] vs. n = 13, median ΔR = 0.1 [-0.3 - 2.2], respectively. In Step 3, the human oocytes with visually intact oolemma showed a statistically significant resistance increase compared to the fragmented ones (n = 96, median ΔR = 1.92 [-0.05 - 6.70] vs. n = 17, median ΔR = 0.11 [0.00 - 0.30], respectively. CONCLUSIONS: An electrical resistance increase can serve as a reliable tool to confirm oocyte penetration and viability, independent of optical visualization. Following further validation and safety assessment, this technology can potentially be integrated into manual and robotic ICSI systems.

Bed rest after an embryo transfer: a systematic review and meta-analysis.

INTRODUCTION: Bed rest for the variable duration is commonly recommended after an embryo transfer (ET) carried out during an in vitro fertilization (IVF). This is based on beliefs that supine position and the reduction of physical activity-to the minimum-might prevent the risk of embryo expulsion once is transferred to the uterus. Therefore, we have designed a meta-analysis based exclusively on evidence from published randomized controlled trials (RCTs), in the attempt to analyze the effectiveness of bed rest after an ET to improve the chance for success in vitro fertilization. METHODS: The review protocol was registered in PROSPERO (CRD42019122758), and data extraction started before protocol publication. Five RCTs were included; 499 women were assigned to the intervention group and 503 to the control group. RESULTS: The analysis of 1002 women did not show any significant change in clinical pregnancy rate between groups [RR 0.86, 95% CI (0.74-1.00), p = 0.06, I2 = 0%]. Likewise, no difference was found in live birth [RR 0.93, 95% CI (0.51-1.69) p = 0.81, I2 = 68%], ongoing pregnancy rate [RR 0.84, 95% CI (0.60-1.20), p = 0.34, I2 = 63%], miscarriage rate [RR 1.08, 95% CI (0.46-2.57), p = 0.86, I2 = 64%], multiple pregnancy rate [RR 0.08, 95% CI (0.50-1.04), p = 0.71, I2 = 0%] or implantation rate [RR 0.90, 95% CI (0.72-1.13), p = 0.38, I2 = 0%]. Subgroup analyses-considering only immediate mobilization or bed rest 24 h-did not show significant differences regarding the outcome. CONCLUSION: Our findings showed that immediate mobilization after an ET does not have a negative influence over the success rates of IVF. Therefore, bed rest should not be recommended.

Mitofusin 1 is required for female fertility and to maintain ovarian follicular reserve.

Mitochondria are dynamic organelles that continually adapt their structure through fusion and fission in response to changes in their bioenergetic environment. Targeted deletion of mitochondrial fusion protein mitofusin1 (MFN1) in oocytes resulted in female infertility associated with failure to achieve oocyte maturation. Oocyte-granulosa cell communication was impaired, and cadherins and connexins were downregulated, resulting in follicle developmental arrest at the secondary follicle stage. Deletion of MFN1 in oocytes resulted in mitochondrial dysfunction and altered mitochondrial dynamics, as well as accumulation of ceramide, which contributed to increased apoptosis and a reproductive phenotype that was partially rescued by treatment with ceramide synthesis inhibitor myriocin. Absence of MFN1 and resulting apoptotic cell loss also caused depletion of ovarian follicular reserve, and a phenotype consistent with accelerated female reproductive aging.

Mitofusin 2 plays a role in oocyte and follicle development, and is required to maintain ovarian follicular reserve during reproductive aging.

Mitochondria change their shape through fusion and fission in order to adapt to their metabolic milieu. Mitofusin-2 (MFN2) is a key regulatory protein in this process, mediating mitochondrial fusion and interaction with endoplasmic reticulum. Targeted deletion of Mfn2 in oocytes resulted in mitochondrial dysfunction and female subfertility associated with impaired oocyte maturation and follicle development. Oocytes lacking MFN2 showed shortened telomeres and increased apoptosis, resulting in compromised oocyte quality and accelerated follicular depletion, consistent with a reproductive aging phenotype.

Translational activation of maternally derived mRNAs in oocytes and early embryos and the role of embryonic poly(A) binding protein (EPAB).

Transcription ceases upon stimulation of oocyte maturation and gene expression during oocyte maturation, fertilization, and early cleavage relies on translational activation of maternally derived mRNAs. Two key mechanisms that mediate translation of mRNAs in oocytes have been described in detail: cytoplasmic polyadenylation-dependent and -independent. Both of these mechanisms utilize specific protein complexes that interact with cis-acting sequences located on 3'-untranslated region (3'-UTR), and both involve embryonic poly(A) binding protein (EPAB), the predominant poly(A) binding protein during early development. While mechanistic details of these pathways have primarily been elucidated using the Xenopus model, their roles are conserved in mammals and targeted disruption of key regulators in mouse results in female infertility. Here, we provide a detailed account of the molecular mechanisms involved in translational activation during oocyte and early embryo development, and the role of EPAB in this process.

Metabolic imaging with the use of fluorescence lifetime imaging microscopy (FLIM) accurately detects mitochondrial dysfunction in mouse oocytes.

OBJECTIVE: To determine whether metabolic imaging with the use of fluorescence lifetime imaging microscopy (FLIM) identifies metabolic differences between normal oocytes and those with metabolic dysfunction. DESIGN: Experimental study. SETTING: Academic research laboratories. PATIENT(S): None. INTERVENTION(S): Oocytes from mice with global knockout of Clpp (caseinolytic peptidase P; n = 52) were compared with wild-type (WT) oocytes (n = 55) as a model of severe oocyte dysfunction. Oocytes from old mice (1 year old; n = 29) were compared with oocytes from young mice (12 weeks old; n = 35) as a model of mild oocyte dysfunction. MAIN OUTCOME MEASURE(S): FLIM was used to measure the naturally occurring nicotinamide adenine dinucleotide dehydrogenase (NADH) and flavin adenine dinucleotide (FAD) autofluorescence in individual oocytes. Eight metabolic parameters were obtained from each measurement (4 per fluorophore): short (τ1) and long (τ2) fluorescence lifetime, fluorescence intensity (I), and fraction of the molecule engaged with enzyme (F). Reactive oxygen species (ROS) levels and blastocyst development rates were measured to assess illumination safety. RESULT(S): In Clpp-knockout oocytes compared with WT, FAD τ1 and τ2 were longer and I was higher, NADH τ2 was longer, and F was lower. In old oocytes compared with young ones, FAD τ1 was longer and I was lower, NADH τ1 and τ2 were shorter, and I and F were lower. FLIM did not affect ROS levels or blastocyst development rates. CONCLUSION(S): FLIM parameters exhibit strong differentiation between Clpp-knockout versus WT, and old versus young oocytes. FLIM could potentially be used as a noninvasive tool to assess mitochondrial function in oocytes.

Mitochondrial unfolded protein response gene Clpp is required to maintain ovarian follicular reserve during aging, for oocyte competence, and development of pre-implantation embryos.

Caseinolytic peptidase P mediates degradation of unfolded mitochondrial proteins and activates mitochondrial unfolded protein response (mtUPR) to maintain protein homeostasis. Clpp-/- female mice generate a lower number of mature oocytes and two-cell embryos, and no blastocysts. Clpp-/- oocytes have smaller mitochondria, with lower aspect ratio (length/width), and decreased expression of genes that promote fusion. A 4-fold increase in atretic follicles at 3 months, and reduced number of primordial follicles at 6-12 months are observed in Clpp-/- ovaries. This is associated with upregulation of p-S6, p-S6K, p-4EBP1 and p-AKT473, p-mTOR2481 consistent with mTORC1 and mTORC2 activation, respectively, and Clpp-/- oocyte competence is partially rescued by mTOR inhibitor rapamycin. Our findings demonstrate that CLPP is required for oocyte and embryo development and oocyte mitochondrial function and dynamics. Absence of CLPP results in mTOR pathway activation, and accelerated depletion of ovarian follicular reserve.

RANKL/RANK Pathway and Its Inhibitor RANK-Fc in Uterine Leiomyoma Growth.

Context: Uterine leiomyomas are the most common type of gynecologic tumor in women. Objective: To determine the role of the cytokine receptor activator of nuclear factor κ-Β ligand (RANKL); its receptor, receptor activator of nuclear factor κ-Β (RANK); and the RANKL/RANK pathway inhibitor RANK-Fc in leiomyoma growth. Design: Messenger RNA (mRNA) or protein levels of RANKL, RANK, and proliferation markers cyclin D1 and Ki67 were assessed in various leiomyoma tissues and cell populations. Human xenograft experiments were performed to determine the effects of RANK-Fc on leiomyoma growth in vivo. Setting: Research laboratory. Patients: Twenty-four regularly cycling premenopausal women (age 28 to 49 years) who were not receiving hormone therapy. Interventions: None. Main Outcome Measure: Tumor growth in a murine xenograft model following targeting of the RANKL/RANK pathway with RANK-Fc. Results: RANKL mRNA levels in leiomyoma were significantly higher than those in myometrial tissues. The highest RANK levels were found in the leiomyoma stem cell population, which is deficient in progesterone receptor (PR). Conversely, the highest RANKL levels were found in the PR-rich leiomyoma intermediate cell (LIC) population. R5020, a PR agonist, specifically increased RANKL expression in LICs. RANK-Fc blocked RANKL-induced expression of the proliferative gene cyclin D1. Treatment with RANK-Fc also significantly decreased tumor growth in vivo and diminished the expression of proliferation marker Ki67 in tumors (P < 0.01; n = 4). Conclusions: Treatment with the RANKL/RANK pathway inhibitor RANK-Fc significantly decreased human leiomyoma cell proliferation and tumor growth. This suggests that the RANKL/RANK pathway could serve as a potential target for the prevention and treatment of uterine leiomyoma.

Thyroid hormone levels in late preterm, early term and term infants: a study with healthy neonates revealing reference values and factors affecting thyroid hormones.

BACKGROUND: Thyroid function tests in neonates have been challenging to interpret because their levels are affected by several neonatal and delivery-related factors. The aim of the study was to evaluate reference values of thyroxine (T4) and thyrotropin (TSH) levels in different gestational age groups and to demonstrate the affect of perinatal factors on thyroid hormones. METHODS: Medical records of 7616 neonates whose gestational age ranges between 34 and 42 weeks were analyzed retrospectively. Gender, mode of delivery, gestational age, postnatal age and birth weight were noted together with TSH and T4 levels. RESULTS: Gestational age (r=0.14, p<0.001) and birth weight (r=0.12, p<0.001) had positive correlation with T4 levels, whereas they had no effect on TSH levels. Males had higher TSH and lower T4 levels (p=0.001 for both) compared with females. T4 levels of babies born via vaginal delivery were lower than the ones born via cesarean section (p=0.01). Multivariable analysis yielded gestational age as the only factor affecting T4 levels (p<0.001). T4 and TSH levels based on 2.5-97.5 percentile cutoffs according to gestational age were presented. CONCLUSIONS: The thyroid hormone ranges given in this study can help pediatricians to interpret the thyroid hormone results with ease.

A Risk Assessment Comparison of Breast Cancer and Factors Affected to Risk Perception of Women in Turkey: A Cross-sectional Study.

BACKGROUND: The increase in breast cancer incidence has enhanced attention towards breast cancer risk. The aim of this study was to determine the risk of breast cancer and risk perception of women, factors that affect risk perception, and to determine differences between absolute risk and the perception of risk. METHODS: This cross-sectional study was carried out among 346 women whose score in the Gail Risk Model (GRM) was ≥ 1.67% and/or had a 1st degree relative with breast cancer in Bahçesehir town in Istanbul, Turkey between Jul 2012 and Dec 2012. Data were collected through face-to-face interviews. The level of risk for breast cancer has been calculated using GRM and the Breast Cancer Risk Assessment Form (BCRAF). Breast cancer risk perception (BCRP), has been evaluated by visual analogue 100-cm-long scale. RESULTS: Even though 39.6% of the women considered themselves as high-risk carriers, according to the GRM and the BCRAF, only 11.6% and 9.8% of women were in the "high risk" category, respectively. There was a positive significant correlation between the GRM and the BCRAF scores (P<0.001), and the BCRAF and BCRP scores (P<0.001). Factors related to high-risk perception were age (40-59 yr), post-menopausal phase, high-very high economic income level, existence of breast cancer in the family, having regular breast self-examination and clinical breast examination (P<0.05). CONCLUSION: In women with high risk of breast, cancer there is a significant difference between the women's risk perception and their absolute risk level.

AMP-activated protein kinase and energy balance in breast cancer.

Cancer growth and metastasis depends on the availability of energy. Energy-sensing systems are critical in maintaining a balance between the energy supply and utilization of energy for tumor growth. A central regulator in this process is AMP-activated protein kinase (AMPK). In times of energy deficit, AMPK is allosterically modified by the binding of increased levels of AMP and ADP, making it a target of specific AMPK kinases (AMPKKs). AMPK signaling prompts cells to produce energy at the expense of growth and motility, opposing the actions of insulin and growth factors. Increasing AMPK activity may thus prevent the proliferation and metastasis of tumor cells. Activated AMPK also suppresses aromatase, which lowers estrogen formation and prevents breast cancer growth. Biguanides can be used to activate AMPK, but AMPK activity is modified by many different interacting factors; understanding these factors is important in order to control the abnormal growth processes that lead to breast cancer neoplasia. Fatty acids, estrogens, androgens, adipokines, and another energy sensor, sirtuin-1, alter the phosphorylation and activation of AMPK. Isoforms of AMPK differ among tissues and may serve specific functions. Targeting AMPK regulatory processes at points other than the upstream AMPKKs may provide additional approaches for prevention of breast cancer neoplasia, growth, and metastasis.

XENON in medical area: emphasis on neuroprotection in hypoxia and anesthesia.

Xenon is a medical gas capable of establishing neuroprotection, inducing anesthesia as well as serving in modern laser technology and nuclear medicine as a contrast agent. In spite of its high cost, its lack of side effects, safe cardiovascular and organoprotective profile and effective neuroprotective role after hypoxic-ischemic injury (HI) favor its applications in clinics. Xenon performs its anesthetic and neuroprotective functions through binding to glycine site of glutamatergic N-methyl-D-aspartate (NMDA) receptor competitively and blocking it. This blockage inhibits the overstimulation of NMDA receptors, thus preventing their following downstream calcium accumulating cascades. Xenon is also used in combination therapies together with hypothermia or sevoflurane. The neuroprotective effects of xenon and hypothermia cooperate synergistically whether they are applied synchronously or asynchronously. Distinguishing properties of Xenon promise for innovations in medical gas field once further studies are fulfilled and Xenon's high cost is overcome.