Ovarian tissue cryopreservation for patients with premature ovary insufficiency caused by cancer treatment: optimal protocol.

Objective: Premature ovary insufficiency is frequent after chemotherapy/radiotherapy in cancer patients. Ovarian tissue (OT) cryopreservation and later retransplantation, the routine method in Europe, has recently been implemented at the first center in China. We investigated the protective effect of the antioxidant N-acetyl-l-cysteine (NAC) during the decisive freezing-thawing steps. Methods: Fifteen OT samples were obtained from each of 13 cancer patients prospectively and randomly assigned to a control group and four groups with different NAC concentrations (Group 1, 0 mM NAC; Group 2, 0.5 mM NAC; Group 3, 1 mM NAC; Group 4, 5 mM NAC; Group 5, 25 mM NAC). After thawing, the follicle viability, DNA fragmentation, levels of reactive oxygen species (ROS), and total antioxidant capacity (TAC) were evaluated. Results: OT cryopreserved and thawed with 25 mM NAC (Group 5) has the lowest proportion of apoptotic stroma cells, but the worst follicle viability. The other four groups show similar anti-apoptosis and good follicle viability. Group 4 presented the lowest ROS and highest TAC levels. Conclusions: OT cryopreserved and thawed in medium supplemented with 5 mM NAC shows the highest antioxidant and lowest ROS capability, good apoptotic parameters, and follicle viability. Our results need to be confirmed in larger patient cohorts prior to being accepted as a standard protocol.

Artificial oocyte activation: evidence for clinical readiness.

Artificial oocyte activation using Ca(2+)ionophores or similar compounds is a widely applied technique in IVF laboratories. This is all the more interesting as most of the agents aiming for intracellular Ca(2+) increase do not result in physiological Ca(2+) oscillations but much rather cause a single Ca(2+) transient. Two observations from mammals may explain why a rather non-physiological single Ca(2+) peak caused by ionophores is sufficient to rescue cycles showing severe male factor infertility, deficient oocyte maturation, developmental problems in humans, or both. On the one hand, it has been shown that it is mainly the initial Ca(2+) rise that drives further downstream events, in particular calcium/calmodulin-dependent protein kinase II (CaMKII) action, and on the other, it is possible that this enzyme remains active even in the absence of Ca(2+). It therefore seems that mammalian oocytes can respond to a wide range of intracellular Ca(2+) signals and have a surprisingly high degree of tolerance for changes in cytosolic Ca(2+). As epigenetic consequences or differences in gene expression have not been studied to date, artificial oocyte activation has to be considered as experimental and should only be applied with a proper indication.

[MR-colonography in hospitalized patients: feasibility and sensitivity]. / MR-Kolonografie bei stationären Patienten: Durchführbarkeit und Sensitivität.

INTRODUCTION: Besides conventional colonoscopy, CT and MR colonography offer alternate virtual imaging modalities of the colon. The sensitivity of CT colonography, which is associated with radiation exposure, has been published in prior, large studies. Regarding MR colonography, in particular dark lumen MR colonography with the rectal administration of a water enema as a contrast agent, only limited published data exist. The goal of this study was to compare MR colonography with conventional colonoscopy in the detection of colorectal polyps. In addition the feasibility and image quality in unselected hospitalised patients were assessed. PATIENTS/METHODS: Included were 103 hospitalised patients who had to undergo colonoscopy for various indications. Immediately prior to conventional colonoscopy, MR colonography with rectal water enema and additional intravenous administration of contrast material was performed. Detection rates for polyps and adenomas were documented with both imaging modalities. Image quality and completion rates (practicability) and other (incidental) findings were also recorded. RESULTS: In 15 of 103 patients the MR examination could not be done or was only partially completed. The detection rate of MR colonography for polyps (adenomas) was 2% (4%) for polyps (adenomas) up to 5 mm in diameter, 38% (56%) for polyps (adenomas) 6-10 mm in diameter and 89% (89%) for polyps (adenomas) up to 11 mm in diameter. One flat carcinoma seen with conventional coloscopy was missed on MR colonography. CONCLUSIONS: MR colonography offers the possibility of imaging the colon without exposure to radiation. Polyps and adenomas are detected, similar to the detection rate of CT colonography, with adequate sensitivity only if they are larger than 10 mm in diameter. Therefore this imaging technique is not (yet) suitable as a screening test. Additional limitations are the necessary cooperation of the patient which can reduce the practicability and image quality in selected patients. Further studies like the just started German multicentre trial are needed to assess the position of MR colonography.