WHO laboratory manual for the examination and processing of human semen

Metastasis is a major cause of death in cancer patients and involves a multistep process including detachment of cancer cells from a primary cancer, invasion of surrounding tissue, spread through circulation, re-invasion and proliferation in distant organs. KiSS-1 is a human metastasis suppressor gene1, that suppresses metastases of human melanomas2 and breast carcinomas3 without affecting tumorigenicity. However, its gene product and functional mechanisms have not been elucidated. Here we show that KiSS-1 (refs 1, 4) encodes a carboxy-terminally amidated peptide with 54 amino-acid residues, which we have isolated from human placenta as the endogenous ligand of an orphan G-protein-coupled receptor (hOT7T175) and have named ‘metastin’. Metastin inhibits chemotaxis and invasion of hOT7T175-transfected CHO cells in vitro and attenuates pulmonary metastasis of hOT7T175-transfected B16-BL6 melanomas in vivo. The results suggest possible mechanisms of action for KiSS-1 and a potential new therapeutic approach.

Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G-protein-coupled receptor.

Background: Many variations in oocyte and embryo grading make inter-laboratory comparisons extremely difficult. This paper reports the proceedings of an international consensus meeting on oocyte and embryo morphology assessment.
Methods: Background presentations about current practice were given.
Results: The expert panel developed a set of consensus points to define the minimumcriteria for oocyte and embryomorphology assessment.
Conclusions: It is expected that the definition of common terminology and standardization of laboratory practice related to embryo morphology assessment will result in more effective comparisons of treatment outcomes. This document is intended to be referenced as a global consensus to allow standardized reporting of the minimum data set required for the accurate description of embryo development.

The Istanbul consensus workshop on embryo assessment: proceedings of an expert meeting

Pregnancy has commonly been viewed as a cooperative interaction between a mother and her fetus. The effects of natural selection on genes expressed in fetuses, however, may be opposed by the effects of natural selection on genes expressed in mothers. In this sense, a genetic conflict can be said to exist between maternal and fetal genes. Fetal genes will be selected to increase the transfer of nutrients to their fetus, and maternal genes will be selected to limit transfers in excess of some maternal optimum. Thus a process of evolutionary escalation is predicted in which fetal actions are opposed by maternal countermeasures. The phenomenon of genomic imprinting means that a similar conflict exists within fetal cells between genes that are expressed when maternally derived, and genes that are expressed when paternally derived. During implantation, fetally derived cells (trophoblast) invade the maternal endometrium and remodel the endometrial spiral arteries into low-resistance vessels that are unable to constrict. This invasion has three consequences. First, the fetus gains direct access to its mother's arterial blood. Therefore, a mother cannot reduce the nutrient content of blood reaching the placenta without reducing the nutrient supply to her own tissues. Second, the volume of blood reaching the placenta becomes largely independent of control by the local maternal vasculature. Third, the placenta is able to release hormones and other substances directly into the maternal circulation. Placental hormones, including human chorionic gonadotropin (hCG) and human placental lactogen (hPL), are predicted to manipulate maternal physiology for fetal benefit. For example, hPL is proposed to act on maternal prolactin receptors to increase maternal resistance to insulin. If unopposed, the effect of hPL would be to maintain higher blood glucose levels for longer periods after meals. This action, however, is countered by increased maternal production of insulin. Gestational diabetes develops if the mother is unable to mount an adequate response to fetal manipulation. Similarly, fetal genes are predicted to enhance the flow of maternal blood through the placenta by increasing maternal blood pressure. Preeclampsia can be interpreted as an attempt by a poorly nourished fetus to increase its supply of nutrients by increasing the resistance of its mother's peripheral circulation.

/pdf/genetic-conflicts-in-human-pregnancy-4ip4vrvtau.pdf

Genetic conflicts in human pregnancy.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.2002.tb02599.x

Sperm chromatin structure assay: its clinical use for detecting sperm DNA fragmentation in male infertility and comparisons with other techniques.

In this study we investigated whether morphology and chromatin anomalies in human spermatozoa can influence fertilization after intracytoplasmic sperm injection (ICSI). We examined unfertilized oocytes, using the fluorochrome Hoechst 33342, to determine whether a relationship exists between failure of fertilization and sperm chromatin quality. Sperm chromatin packaging quality was assessed using the chromomycin A3 (CMA3) fluorochrome, and the presence of DNA damage in spermatozoa, using in-situ nick translation, Normal males present sperm parameters with a normal morphology of > 20%, CMA3 fluorescence of < 30% and exhibit endogenous nicks in < 10% of their spermatozoa. When patients were separated according to these values no difference was observed in their fertilization rates after ICSI. When the unfertilized ICSI oocytes were examined, we found that patients with CMA3 fluorescence of <30% and nicks in < 10% of their spermatozoa had only 17.5 and 21.6% respectively of their unfertilized oocytes containing spermatozoa that remained condensed. In contrast, patients with higher CMA3 and nick values had a significantly higher number, 41.2 and 48.9%, of their unfertilized oocytes containing condensed spermatozoa. sperm morphology did not show any such pattern. The percentage of spermatozoa which had initiated decondensation in unfertilized oocytes was not influenced by morphology, CMA3 fluorescence or nicks. In light of these results we postulate that poor chromatin packaging and/or damaged DNA may contribute to failure of sperm decondensation after ICSI and result in failure of fertilization.

/pdf/sperm-chromatin-anomalies-can-influence-decondensation-after-2ln5ryok65.pdf

Sperm chromatin anomalies can influence decondensation after intracytoplasmic sperm injection

9/27 (33.3%), compared with the no early cleavage group, the relationship between early cleavage of embryos and the 17/116 (14.7%). No difference was found when comparing incidence of pregnancy. Furthermore, we propose that this key parameters (age, stimulation protocol and semen charmay be used as a simple and effective selection criterion for acteristics) of couples belonging to both groups, pointing selecting embryos for transfer. to an intrinsic property or factor(s) within the early cleaving embryos. We propose ‘early cleavage’ as a simple and effective non-invasive method for selection and evaluation of embryos prior to transfer. Materials and methods

/pdf/early-cleavage-of-in-vitro-fertilized-human-embryos-to-the-2-3qhqlx33kk.pdf

Early cleavage of in-vitro fertilized human embryos to the 2-cell stage: a novel indicator of embryo quality and viability.

In-vitro fertilization (IVF) embryos are selected for transfer on the basis of morphology and rate of development. However, when a number of embryos have similar characteristics, the selection of the best embryos is left to chance. Recently, we proposed a simple, novel method to overcome this problem, based on pre-selection of embryos cleaving early to the two-cell stage. In this study we have adopted the same method to choose embryos fertilized after intracytoplasmic sperm injection (ICSI). Fertilized embryos that had cleaved to the two-cell stage by 27 h post-injection were designated as 'early cleavage' embryos, while those that had not yet reached the two-cell stage were designated as 'no early cleavage'. In all cases, the early cleavage embryos were transferred when available. Early cleavage was observed in 54 (61.4%) of the 88 cycles assessed. There were significantly (P = 0.04) more clinical pregnancies in the early cleavage group, 14/54 (25.9%), compared with the no early cleavage group 2/34 (3.2%). No differences between the groups were found when comparing key parameters (age, stimulation protocol and semen characteristics) of the couples. Using the ICSI technique, we have shown that early cleavage to the two-cell stage is not influenced by the timing of fertilization, and is more likely due to intrinsic factors within the oocyte or embryo that promote embryo cleavage after fertilization.

Early cleavage of human embryos to the two-cell stage after intracytoplasmic sperm injection as an indicator of embryo viability.

In the first part of this report we investigate whether chromatin anomalies in human spermatozoa can influence fertilization after intracytoplasmic sperm injection (ICSI). We have examined the sperm chromatin packaging quality using the chromomycin A3 (CMA3) fluorochrome and the presence of DNA damage in spermatozoa using in-situ nick translation. When comparing the spermatozoa of patients undergoing in-vitro fertilization (IVF) and ICSI distinct differences are evident in that ICSI males have a higher CMA3 fluorescence, indicating spermatozoa with loosely packed chromatin, and more spermatozoa containing endogenous DNA nicks. When examining the unfertilized oocytes of ICSI patients we found that men who had a high percentage of anomalies in their chromatin, i.e. > 30% CMA3 fluorescence and > 10% nicks, had more than double the number of unfertilized oocytes containing spermatozoa that had remained condensed. The observation that failed fertilized oocytes, injected with spermatozoa from patients with a higher percentage of sperm nuclear anomalies, contain more condensed spermatozoa indicates that a selection process against these spermatozoa may be in place at the time of fertilization. In the second part of the study we show that spare ICSI embryos have significantly lower rates of development to the blastocyst stage compared with those developed after routine IVF. These results show that a greater understanding of the molecular basis of male infertility is therefore needed to broaden our knowledge on the effect that abnormal spermatozoa have on fertilization and embryo development.

/pdf/sperm-nuclear-dna-damage-and-altered-chromatin-structure-3dqrazn4jy.pdf

Aldo Campana

Papers

Sperm chromatin anomalies can influence decondensation after intracytoplasmic sperm injection

Early cleavage of in-vitro fertilized human embryos to the 2-cell stage: a novel indicator of embryo quality and viability.

Early cleavage of human embryos to the two-cell stage after intracytoplasmic sperm injection as an indicator of embryo viability.

Sperm nuclear DNA damage and altered chromatin structure: effect on fertilization and embryo development

Paracrine and autocrine regulators of trophoblast invasion: A review