Effects of pulse repetition frequency on bubble cloud characteristics and ablation in single-cycle histotripsy.

Objective. Histotripsy is a cavitation-based ultrasound ablation method in development for multiple clinical applications. This work investigates the effects of pulse repetition frequency (PRF) on bubble cloud characteristics and ablative capabilities for histotripsy using single-cycle pulsing methods.Approach.Bubble clouds produced by a 500 kHz histotripsy system at PRFs from 0.1 to 1000 Hz were visualized using high-speed optical imaging in 1% agarose tissue phantoms at peak negative pressures,p-, of 2-36 MPa.Main results.Results showed a decrease in the cavitation cloud threshold with increasing PRF, ranging from 26.7 ± 0.5 MPa at 0.1 Hz to 15.0 ± 1.9 MPa at 1000 Hz. Bubble cloud analysis showed cavitation clouds generated at low PRFs (0.1-1 Hz) were characterized by consistently dense bubble clouds (41.7 ± 2.8 bubbles mm-2at 0.1 Hz), that closely matched regions of the focus above the histotripsy intrinsic threshold. Bubble clouds formed at higher PRFs measured lower cloud densities (23.1 ± 4.0 bubbles mm-2at 1000 Hz), with the lowest density measured for 10 Hz (8.8 ± 4.1 bubbles mm-2). Furthermore, higher PRFs showed increased pulse-to-pulse correlation, characteristic of cavitation memory effects; however, bubble clouds still filled the entire volume of the focus due to their initial density and enhanced bubble expansion from the restimulation of residual nuclei at the higher PRFs. Histotripsy ablation assessed through lesion analysis in red blood cell (RBC) phantoms showed higher PRFs generated lesions with lower adherence to the initial focal region compared to low PRF ablations; however, no trend of decreasing ablation efficiency with PRF was observed, with similar efficiencies observed for all the PRFs tested in this study.Significance.Notably, this result is different than what has previously been shown for shock-scattering histotripsy, which has shown decreased ablation efficiencies at higher PRFs. Overall, this study demonstrates the essential effects of PRF on single-cycle histotripsy procedures that should be considered to help guide future histotripsy pulsing strategies.

Ablative and Immunostimulatory Effects of Histotripsy Ablation in a Murine Osteosarcoma Model.

Background: Osteosarcoma (OS) is the most frequently occurring malignant bone tumor in humans, primarily affecting children and adolescents. Significant advancements in treatment options for OS have not occurred in the last several decades, and the prognosis remains grim with only a 70% rate of 5-year survival. The objective of this study was to investigate the focused ultrasound technique of histotripsy as a novel, noninvasive treatment option for OS. Methods: We utilized a heterotopic OS murine model to establish the feasibility of ablating OS tumors with histotripsy in a preclinical setting. We investigated the local immune response within the tumor microenvironment (TME) via immune cell phenotyping and gene expression analysis. Findings: We established the feasibility of ablating heterotopic OS tumors with ablation characterized microscopically by loss of cellular architecture in targeted regions of tumors. We observed greater populations of macrophages and dendritic cells within treated tumors and the upregulation of immune activating genes 72 h after histotripsy ablation. Interpretation: This study was the first to investigate histotripsy ablation for OS in a preclinical murine model, with results suggesting local immunomodulation within the TME. Our results support the continued investigation of histotripsy as a novel noninvasive treatment option for OS patients to improve clinical outcomes and patient prognosis.

Profiling mouse brown and white adipocytes to identify metabolically relevant small ORFs and functional microproteins.

Microproteins (MPs) are a potentially rich source of uncharacterized metabolic regulators. Here, we use ribosome profiling (Ribo-seq) to curate 3,877 unannotated MP-encoding small ORFs (smORFs) in primary brown, white, and beige mouse adipocytes. Of these, we validated 85 MPs by proteomics, including 33 circulating MPs in mouse plasma. Analyses of MP-encoding mRNAs under different physiological conditions (high-fat diet) revealed that numerous MPs are regulated in adipose tissue in vivo and are co-expressed with established metabolic genes. Furthermore, Ribo-seq provided evidence for the translation of Gm8773, which encodes a secreted MP that is homologous to human and chicken FAM237B. Gm8773 is highly expressed in the arcuate nucleus of the hypothalamus, and intracerebroventricular administration of recombinant mFAM237B showed orexigenic activity in obese mice. Together, these data highlight the value of this adipocyte MP database in identifying MPs with roles in fundamental metabolic and physiological processes such as feeding.

Histotripsy for the Treatment of Uterine Leiomyomas: A Feasibility Study in Ex Vivo Uterine Fibroids.

Uterine fibroids (leiomyomas), the most common benign tumors in women of reproductive age, are a frequent cause of abnormal vaginal bleeding and other reproductive complaints among women. This study investigates the feasibility of using histotripsy, a non-invasive, non-thermal focused ultrasound ablation method, to ablate uterine fibroids. Human fibroid samples (n = 16) were harvested after hysterectomy or myomectomy procedures at Carilion Memorial Hospital. Histotripsy was applied to ex vivo fibroids in two sets of experiments using a 700-kHz clinical transducer to apply multicycle histotripsy pulses and a prototype 500-kHz transducer to apply single-cycle histotripsy pulses. Ultrasound imaging was used for real-time treatment monitoring, and post-treatment ablation was quantified histologically using hematoxylin and eosin and Masson trichrome stains. Results revealed that multicycle histotripsy generated diffuse cavitation in targeted fibroids, with minimal cellular ablative changes after treatment with 2000 pulses/point. Single-cycle pulsing generated well-confined bubble clouds with evidence of early coagulative necrosis on histological assessment in samples treated with 2000 pulses/point, near-complete ablation in samples treated with 4000 pulses/point and complete tissue destruction in samples treated with 10,000 pulses/point. This study illustrates that histotripsy is capable of fibroid ablation under certain pulsing parameters and warrants further investigation as an improved non-invasive ablation method for the treatment of leiomyomas.

Histotripsy Ablation in Preclinical Animal Models of Cancer and Spontaneous Tumors in Veterinary Patients: A Review.

New therapeutic strategies are direly needed in the fight against cancer. Over the last decade, several tumor ablation strategies have emerged as stand-alone or combination therapies. Histotripsy is the first completely noninvasive, nonthermal, and nonionizing tumor ablation method. Histotripsy can produce consistent and rapid ablations, even near critical structures. Additional benefits include real-time image guidance, high precision, and the ability to treat tumors of any predetermined size and shape. Unfortunately, the lack of clinically and physiologically relevant preclinical cancer models is often a significant limitation with all focal tumor ablation strategies. The majority of studies testing histotripsy for cancer treatment have focused on small animal models, which have been critical in moving this field forward and will continue to be essential for providing mechanistic insight. While these small animal models have notable translational value, there are significant limitations in terms of scale and anatomical relevance. To address these limitations, a diverse range of large animal models and spontaneous tumor studies in veterinary patients have emerged to complement existing rodent models. These models and veterinary patients are excellent at providing realistic avenues for developing and testing histotripsy devices and techniques designed for future use in human patients. Here, we provide a review of animal models used in preclinical histotripsy studies and compare histotripsy ablation in these models using a series of original case reports across a broad spectrum of preclinical animal models and spontaneous tumors in veterinary patients.

Do vitrified frozen-thawed embryos generated from successful fresh cycles have higher potential for favorable outcome?

BACKGROUND: Many variables, including woman's age, embryo quality and endometrial receptivity, influence the success rate of either fresh embryo transfer (ET) or frozen-thawed ET (FT-ET) cycles. This study aims to examine whether the results of a fresh in-vitro fertilization (IVF) cycle correlate with its frozen-thawed embryos transfer outcomes. METHODS: A retrospective cohort study conducted in a tertiary medical center single IVF unit between 2014-2017. The study population was comprised of women who underwent fresh ET with the remaining embryos frozen using vitrification and at least one consecutive FT-ET cycle. Comparison of FT-ET cycle's details and outcomes were assessed in relation to the outcome of preceding fresh ET cycle. RESULTS: A total of 599 women underwent fresh ET and at least one consecutive FT-ET cycle. Significantly higher rates of successful FT-ET cycle outcomes were observed in the group of patients with a successful fresh cycle compared to the group with an unsuccessful fresh cycle (48.9% vs. 20.8%, P<0.001). Logistic regression demonstrated an adjusted OR of 5.02 for successful FT-ET after a successful fresh cycle. CONCLUSIONS: Frozen-thawed embryos generated from successful fresh IVF cycles have higher potential to implant when compared to frozen-thawed embryos obtained in an unsuccessful fresh cycle.

Endometrial thickness following early miscarriage in IVF patients - is there a preferred management approach?

BACKGROUND: Endometrial thickness (ET) has previously been shown to positively correlate with implantation and clinical pregnancy rates. Pregnancies achieved using in-vitro fertilization (IVF) technique are prone to higher rates of early miscarriage. The aim of this study was to compare the effects of expectant management, medical treatment (Misoprostol) and dilation and curettage (D&C) for early miscarriage following IVF cycles on the subsequent cycle outcomes - endometrial thickness and reproductive outcomes. METHODS: A retrospective cohort study of women who underwent embryo transfer, conceived and had first trimester miscarriage with at least one subsequent embryo transfer. ET measurements during fresh or frozen-thawed IVF cycles were assessed for each patient. Comparisons of ET differences between the miscarriage and the subsequent cycles, as well as reproductive outcomes, were performed according to the initial miscarriage management approach. RESULTS: A total of 223 women were included in the study. Seventy-eight women were managed conservatively, 61 were treated with Misoprostol and 84 women underwent D&C. Management by D&C, compared to conservative management and Misoprostol treatment was associated with higher prevalence of a significant (> 2 mm) ET decrease (29.8%% vs. 14.1and 6.6%, respectively; p < .001) and was the only approach associated with a significant increase in the rates of ET under 7 and 8 mm in the following cycle (p = 0.006 and 0.035; respectively). Clinical pregnancy rates were significantly lower following D&C compared with conservative management and Misoprostol (16.7% vs. 38.5 and 27.9%, respectively; p = 0.008) as well as implantation rate (11.1% vs. 30.5.% and 17.7, respectively; p < 0.001). CONCLUSION: Our data suggest that D&C management of a miscarriage is associated with decreased ET and higher rates of thin endometrium in the subsequent IVF cycle, compared with conservative management and Misoprostol treatment. In addition, implantation and pregnancy rates were significantly lower after D&C.

Histotripsy for the Treatment of Cholangiocarcinoma Liver Tumors: In Vivo Feasibility and Ex Vivo Dosimetry Study.

Histotripsy is a noninvasive, nonionizing, and nonthermal focused ultrasound ablation method that is currently being developed for the treatment of liver cancer. Promisingly, histotripsy has been shown for ablating primary [hepatocellular carcinoma (HCC)] and metastatic [colorectal liver metastasis (CLM)] liver tumors in preclinical and early clinical studies. The feasibility of treating cholangiocarcinoma (CC), a less common primary liver tumor that arises from the bile ducts, has not been explored previously. Given that prior work has established that histotripsy susceptibility is based on tissue mechanical properties, there is a need to explore histotripsy as a treatment for CC due to its dense fibrotic stromal components. In this work, we first investigated the feasibility of histotripsy for ablating CC tumors in vivo in a patient-derived xenograft mouse model. The results showed that histotripsy could generate CC tumor ablation using a 1-MHz small animal histotripsy system with treatment doses of 250, 500, and 1000 pulses/point. The second set of experiments compared the histotripsy doses required to ablate CC tumors to HCC and CLM tumors ex vivo. For this, human tumor samples were harvested after surgery and treated ex vivo with a 700-kHz clinical histotripsy transducer. Results demonstrated that significantly higher treatment doses were required to ablate CC and CLM tumors compared to HCC, with the highest treatment dose required for CC tumors. Overall, the results of this study suggest that histotripsy has the potential to be used for the ablation of CC tumors while also highlighting the need for tumor-specific treatment strategies.

Emergence of complexity in hierarchically organized chiral particles.

The structural complexity of composite biomaterials and biomineralized particles arises from the hierarchical ordering of inorganic building blocks over multiple scales. Although empirical observations of complex nanoassemblies are abundant, the physicochemical mechanisms leading to their geometrical complexity are still puzzling, especially for nonuniformly sized components. We report the self-assembly of hierarchically organized particles (HOPs) from polydisperse gold thiolate nanoplatelets with cysteine surface ligands. Graph theory methods indicate that these HOPs, which feature twisted spikes and other morphologies, display higher complexity than their biological counterparts. Their intricate organization emerges from competing chirality-dependent assembly restrictions that render assembly pathways primarily dependent on nanoparticle symmetry rather than size. These findings and HOP phase diagrams open a pathway to a large family of colloids with complex architectures and unusual chiroptical and chemical properties.

Cancer in IVF patients treated at age 40 years and older: long term follow-up.

RESEARCH QUESTION: Current knowledge of cancer risk among women who undergo IVF is based mainly on studies of women treated in their thirties, frequently with short follow-up periods. Therefore, information about cancer risk among infertile menopausal women is limited. We aimed to evaluate the risk of cancer among IVF patients treated at age 40 years and older, followed up for an extended period. DESIGN: Historical cohort study of all IVF patients treated at the age of 40 years or older at two university-affiliated IVF units in Jerusalem, Israel, between 1994 and 2002. Data were cross-linked with the Israel National Cancer Registry to 2016. Standardized incidence ratios (SIR) and 95% confidence intervals were computed by comparing the observed number of cancer cases with the expected cancer rate in the general Israeli population adjusted for age and year of birth. In addition, Kaplan-Meier analysis was conducted to account for the length of follow-up. RESULTS: A total of 501 patients were included in the analysis, with mean follow-up of 16.7 ± 3.7 years (range 2-22 years). Mean age at first IVF cycle was 42.3 years (±2.1). Mean number of IVF cycles was 3.2 ± 2.6 (range 1-15). Thirty-six women (7.2%) developed invasive cancer, compared with 47.2 expected cases; SIR 0.76 (95% CI 0.53 to 1.06); 22 women were diagnosed with invasive breast cancer, compared with 19.84 expected; SIR 1.11 (95% CI 0.69 to 1.68). CONCLUSIONS: Older women undergoing IVF treatment were not significantly associated with an excess risk of cancer at long-term follow up. Further studies, however, are needed to confirm these findings.

Prior Binge Ethanol Exposure Potentiates the Microglial Response in a Model of Alcohol-Induced Neurodegeneration.

Excessive alcohol consumption results in neurodegeneration which some hypothesize is caused by neuroinflammation. One characteristic of neuroinflammation is microglial activation, but it is now well accepted that microglial activation may be pro- or anti-inflammatory. Recent work indicates that the Majchrowicz model of alcohol-induced neurodegeneration results in anti-inflammatory microglia, while intermittent exposure models with lower doses and blood alcohol levels produce microglia with a pro-inflammatory phenotype. To determine the effect of a repeated binge alcohol exposure, rats received two cycles of the four-day Majchrowicz model. One hemisphere was then used to assess microglia via immunohistochemistry and while the other was used for ELISAs of cytokines and growth factors. A single binge ethanol exposure resulted in low-level of microglial activation; however, a second binge potentiated the microglial response. Specifically, double binge rats had greater OX-42 immunoreactivity, increased ionized calcium-binding adapter molecule 1 (Iba-1+) cells, and upregulated tumor necrosis factor-α (TNF-α) compared with the single binge ethanol group. These data indicate that prior ethanol exposure potentiates a subsequent microglia response, which suggests that the initial exposure to alcohol primes microglia. In summary, repeated ethanol exposure, independent of other immune modulatory events, potentiates microglial activity.

Chronic Administration of the N-Methyl-D-Aspartate Receptor Antagonist Ketamine Improves Rett Syndrome Phenotype.

BACKGROUND: Rett syndrome (RTT) is a neurological disorder caused by mutation of the X-linked MECP2 gene, which results in the progressive disruption of excitatory and inhibitory neuronal circuits. To date, there is no effective treatment available for the disorder. Studies conducted in RTT patients and murine models have shown altered expression of N-methyl-D-aspartate receptors (NMDARs). Genetic deletion of the NMDAR subunit, GluN2A, in mice lacking Mecp2 is sufficient to prevent RTT phenotypes, including regression of vision. METHODS: We performed a systematic, randomized preclinical trial of chronic administration of low-dose (8 mg/kg, intraperitoneal) ketamine, an NMDAR antagonist, starting either early in development or at the onset of RTT phenotype in Mecp2-null mice. RESULTS: Daily exposure to ketamine ameliorated RTT symptoms and extended the life span of treated Mecp2-null mice without adverse side effects. Furthermore, significant improvement was observed in cortical processing and connectivity, which were fully restored to a wild-type level, particularly when treatment was started at the onset of regression. CONCLUSIONS: Our findings provide strong evidence that targeting NMDA receptors can be a safe and effective treatment for RTT.

Operative hysteroscopy for treatment of intrauterine pathologies does not interfere with later endometrial development in patients undergoing in vitro fertilization.

PURPOSE: Operative hysteroscopy procedure is extensively used for the treatment of intrauterine abnormalities that can potentially cause infertility. To date, there are little data addressing the effect of operative hysteroscopy that applies electrical current for excision and its subsequent effect on endometrial thickness. This study was aimed to assess the effect of thermal resection used in operative hysteroscopy on endometrial thickness and on fertility outcome in women undergoing in vitro fertilization (IVF). METHODS: A retrospective study conducted at Hadassah-Hebrew University Medical Center, a tertiary referral center. Included were IVF women who underwent an operative hysteroscopy throughout the years 2000-2010 for intrauterine pathologies. RESULTS: Throughout the years 2000-2010, 41 IVF women who underwent an operative hysteroscopy using electric current between their 82 IVF cycles were studied. The mean age of women at the time of the intervention was 37.1 years (36.7 and 37.5 at the IVF cycles before and after intervention, respectively). The maximal endometrial thickness before operative hysteroscopy was 10.7 mm compared to 9.5 mm after all procedures (P < 0.001). Excluding polypectomy cases (n = 24) the endometrial thickness was 9.9 mm before vs. 9.1 mm after operative hysteroscopy (P < 0.001). The clinical pregnancy rate was 19.5 % before as compared to 24.4 % after operative hysteroscopy (NS). The take home baby rate (THBR), however, was significantly increased following operative hysteroscopy for all indications from 2.4 to 12.2 % (P < 0.05). CONCLUSION: Despite the small change in endometrial thickness, our results indicate that using electric current is safe to treat intrauterine pathologies.

Assessment of the Effects of 6 Standard Rodent Diets on Binge-Like and Voluntary Ethanol Consumption in Male C57BL/6J Mice.

BACKGROUND: In recent years, much attention has been given to the lack of reproducibility in biomedical research, particularly in preclinical animal studies. This is a problem that also plagues the alcohol research field, particularly in consistent consumption in animal models of alcohol use disorders. One often overlooked factor that could affect reproducibility is the maintenance diet used in preclinical studies. METHODS: Herein, 2 well-established models of alcohol consumption, the "drinking in the dark" (DID) procedure and the continuous 2-bottle choice (C2BC) paradigm, were employed to determine the effects of diet on ethanol (EtOH) consumption. Male C57BL/6J mice were given 1 of 6 standard rodent chow diets obtained from Purina LabDiet(®) , Inc. (Prolab(®) RMH 3000) or Harlan(®) Laboratories, Inc. (Teklad Diets T.2916, T.2918, T.2920X, T.7912, or T.8940). A separate group of animals were used to test dietary effects on EtOH pharmacokinetics and behavioral measures following intraperitoneal (IP) injections of various doses of EtOH. RESULTS: Mice eating Harlan diets T.2916 (H2916) and T.2920X (H2920) consumed significantly less EtOH and exhibited lower blood EtOH concentrations (BECs) during DID; however, during C2BC, animals maintained on Harlan T.7912 (H7912) consumed more EtOH and had a higher EtOH preference than the other diet groups. EtOH consumption levels did not stem from changes in alcohol pharmacokinetics, as a separate group of animals administered EtOH IP showed no difference in BECs. However, animals on Harlan diet T.2920X (H2920) were more sensitive to alcohol-induced locomotor activity in an open-field task. No diet-dependent differences were seen in alcohol-induced sedation as measured with loss of righting reflex. CONCLUSIONS: Although these data do not identify a specific mechanism, together, they clearly show that the maintenance diet impacts EtOH consumption. It is incumbent upon the research community to consider the importance of describing nutritional information in methods, which may help decrease interlaboratory reproducibility issues.

[Fertility treatment options for discordant couples living with HIV].

BACKGROUND: Serodiscordant couples live with the risk of HIV infection of the negative partner when attempting to become pregnant. Using density gradient centrifugation (DGC), spermatozoa can be separated from other seminal compartments. Isolated spermatozoa do not contain detectable HIV RNA. DGC followed by artificial insemination may significantly reduce the risk of infection. The Hadassah AIDS Center (HAC) has recently initiated a fertility center for serodiscordant couples. METHODS: Our patient population includes serodiscordant couples in which the male is HIV positive. The male semen is washed using the DGC procedure. Washed semen is tested for HIV by standard PCR methods. Intrauterine insemination (IUI) is attempted using the washed semen. RESULTS: A total of 55 couples have registered for this procedure. This includes 16 men who have sex with men, 7 who have hemophilia and 8 couples of Ethiopian origin. The average female age is 33 years. Seven (12%) men had inadequate sperm counts and were referred for IVF. Overall, 34 semen samples were tested for HIV. Only one was found to be positive. During the procedure, 22 couples underwent at least one IUI attempt and 16 (72%) females became pregnant, 3 of them after the first IUI attempt. All women tested for HIV after IUI were found to be negative. CONCLUSIONS: The pregnancy success rate during the first year of operation was 72%, similar to that reported by other centers in Europe. There were no seroconversions of the female partner. Serodiscordant couples living with HIV in Israel today may consider starting a family, while significantly reducing the risk of infecting the negative female partner.

3D viability imaging of tumor phantoms treated with single-walled carbon nanohorns and photothermal therapy.

A new image analysis method called the spatial phantom evaluation of cellular thermal response in layers (SPECTRL) is presented for assessing spatial viability response to nanoparticle enhanced photothermal therapy in tissue representative phantoms. Sodium alginate phantoms seeded with MDA-MB-231 breast cancer cells and single-walled nanohorns were laser irradiated with an ytterbium fiber laser at a wavelength of 1064 nm and irradiance of 3.8 W cm(-2) for 10-80 s. SPECTRL quantitatively assessed and correlated 3D viability with spatiotemporal temperature. Based on this analysis, kill and transition zones increased from 3.7 mm(3) and 13 mm(3) respectively to 44.5 mm(3) and 44.3 mm(3) as duration was increased from 10 to 80 s. SPECTRL provides a quantitative tool for measuring precise spatial treatment regions, providing information necessary to tailor therapy protocols.

Assessment and treatment of repeated implantation failure (RIF).

Repeated implantation failure (RIF) is determined when embryos of good quality fail to implant following several in vitro fertilization (IVF) treatment cycles. Implantation failure is related to either maternal factors or embryonic causes. Maternal factors include uterine anatomic abnormalities, thrombophilia, non-receptive endometrium and immunological factors. Failure of implantation due to embryonic causes is associated with either genetic abnormalities or other factors intrinsic to the embryo that impair its ability to develop in utero, to hatch and to implant. New methods of time-lapse imaging of embryos and assessment of their metabolic functions may improve selection of embryos for transfer, and subsequent outcomes for IVF patients, as well as for those diagnosed with RIF. This review discusses the various causes associated with RIF and addresses appropriate treatments.

Derivation of xeno-free and GMP-grade human embryonic stem cells--platforms for future clinical applications.

Clinically compliant human embryonic stem cells (hESCs) should be developed in adherence to ethical standards, without risk of contamination by adventitious agents. Here we developed for the first time animal-component free and good manufacturing practice (GMP)-compliant hESCs. After vendor and raw material qualification, we derived xeno-free, GMP-grade feeders from umbilical cord tissue, and utilized them within a novel, xeno-free hESC culture system. We derived and characterized three hESC lines in adherence to regulations for embryo procurement, and good tissue, manufacturing and laboratory practices. To minimize freezing and thawing, we continuously expanded the lines from initial outgrowths and samples were cryopreserved as early stocks and banks. Batch release criteria included DNA-fingerprinting and HLA-typing for identity, characterization of pluripotency-associated marker expression, proliferation, karyotyping and differentiation in-vitro and in-vivo. These hESCs may be valuable for regenerative therapy. The ethical, scientific and regulatory methodology presented here may serve for development of additional clinical-grade hESCs.

Human granulosa luteal cell oxidative phosphorylation function is not affected by age or ovarian response.

OBJECTIVE: To safely prepare a functional autologous mitochondrial concentrate (MC) from follicular fluid (FF) cells, and to determine the effect of age and ovarian response on the oxidative phosphorylation (OXPHOS). DESIGN: The nontoxicity of the MC was confirmed in human and mouse oocytes. The OXPHOS function was assessed by measuring the activity of succinate dehydrogenase (SDH) and cytochrome c oxidase (COX), and adenosine triphosphate (ATP) production in comparison with citrate synthase. The integrity of the mitochondrial DNA (mtDNA) was demonstrated by polymerase chain reaction (PCR). SETTING: Tertiary hospital. PATIENT(S): A total of 40 patients undergoing IVF of heterogeneous ages and ovarian response. ANIMAL(S): Superovulated 8- to 12-week-old female B(6)C(3)F(1) mice. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): A system for the preparation of functional nontoxic MC was established. The correlation between the mitochondrial mass and function to age and ovarian response was calculated. The integrity of mtDNA was demonstrated. RESULT(S): After injection into mouse oocytes, the MC did not interfere with parthenogenetic development. The MC OXPHOS function was intact. Total activity of SDH and COX was in correlation with the retrieved oocytes number, and in reverse correlation with age. However, after correction to the mitochondrial mass, COX and SDH activities were constant, unaffected by age or ovarian response. The mtDNA was intact in all samples, regardless of age and ovarian response. CONCLUSION(S): The function of the respiratory chain in mitochondria of FF cells is constant, unaffected by age or ovarian response.

Recurrent implantation failure: current update and clinical approach to an ongoing challenge.

A better understanding of the mechanisms responsible for implantation may improve our ability to treat RIF and improve IVF results in general. This issue's Views and Reviews aims to summarize the current knowledge on mechanisms involved in recurrent implantation failure and presents a clinical approach and potential treatments to overcome the problem.