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Two recent tests have claimed to identify the subfertile male even when other semen parameters were normal: the sperm chromatin structure assay (SCSA) and abnormal sperm nuclear morphology using much higher magnification. The present study attempted to determine if having a high (> 30%) DNA fragmentation index (DFI), thus resulting in an abnormal SCSA test, is associated with a greater likelihood of sperm with abnormal nuclei. Four males with high DFI scores (57.6%, 65.4%, 31.0%, and 35.3%) had their nuclei evaluated by a complex microscope set-up that magnifies the sperm at least 6000 × . The corresponding % of normal nuclei was 0%, 20.0%, 23.7% and 40.0%. The mean and median % of normal nuclei was 20.9±16.43 and 21.8, respectively. More studies of similarly matched refractory in vitro fertilization cases, where males have normal DFI scores, are needed to determine if having a high DFI index is associated with a lower percentage of normal nuclei.

A subnormal sperm stress test has also been associated with implantation failure despite apparently normal fertilization; however, this test is cumbersome and time-consuming. The overnight sperm survival test has been considered to possibly demonstrate lipid peroxidation abnormalities similar to the sperm stress test. The present study evaluated whether lower overnight survival scores were associated with lower pregnancy and implantation rates following in vitro fertilization-embryo transfer. The results showed no adverse effect of poor overnight survival test scores. Possibly, the overnight survival test, though similar in some respects to the sperm stress test, is not similar for properties of predicting embryo implantation defects. Corroboration that subnormal stress tests predicts implantation disorders is needed.

A study has suggested that one drawback of ICSI is that if these embryos are cryopreserved they have lower implantation rates after thawing and transfer as compared to other frozen embryos derived from conventional oocyte insemination. Other studies have not shown such adverse effects on pregnancy rates following frozen embryo transfer (ET) of embryos formed by ICSI. The study presented here evaluated the largest number of frozen ET cycles of embryos following ICSI, which were compared to couples having frozen ET with embryos formed by conventional insemination. In women age 39 and younger, the clinical, viable, pregnancy rates and implantation rates were very similar. Similar rates were reached for the older group. These data convincingly demonstrate that fertilization by ICSI does not adversely effect the implanting capacity of frozen-thawed embryos.

BACKGROUND: Recipients of donor oocytes need to be synchronized to the donor's cycle if fresh embryos are to be transferred on the cycle of oocyte retrieval. It would be much easier to merely retrieve the oocytes from the donor, fertilize the oocytes with the recipient's male partner's spermatozoa, cryopreserve the embryos, then transfer on an oestrogen/progesterone treatment programme. METHODS: The IVF outcomes of all patients enrolled in a shared oocyte programme from January 1997 to June 1999 were reviewed. Pregnancy and implantation rates were computed and statistically analysed. RESULTS: There was a significantly higher clinical pregnancy rate for recipients who had a fresh embryo transfer compared with recipients whose first embryo transfer consisted of frozen/thawed embryos (63.4 versus 43.6%). CONCLUSIONS: Conception is more likely after fresh than frozen embryo transfer with recipients but is similar to donor conception rates. If a uterine defect, per se, even without the use of the controlled ovarian stimulation regimen, could explain the difference between fresh pregnancy and implantation rates in donors versus recipients, then these same differences would have been seen when comparing frozen transfers, but they were, in fact, similar.

Background & Aims: Src activation is reported as an early event found in preneoplastic colonic adenomas and in 70% of colon carcinomas. The aim of this study was to identify the biological consequences of c-src overexpression in rat colon epithelial cells. Methods: Introduction and overexpression of c-src in an immortalized rat colon epithelial cell line was achieved using lipofection. Transfectants were tested for changes in growth and cell behavior using different in vitro assay systems. Results: Colon epithelial cells overexpressing c-src showed the ability to form microcolonies in soft agar without acquiring tumorigenic potential. In in vitro assays, c-src transfectants displayed a gain of invasive potential through Matrigel without an accompanying change in migrational ability. No discernible qualitative changes were observed in the phosphotyrosyl protein profile between c-src and v-src transfectants. Assessment of the cadherin/catenin status in these cells revealed an intact, functional complex with no detectable tyrosine phosphorylation of different components of the complex. Conclusions: Overexpression of c-src in an immortalized rat colon epithelial cell line does not elicit full neoplastic transformation but enhances anchorage-independent growth and confers invasion capability. Increased invasion through Matrigel was not linked to inactivation of the cadherin complex in c-src transfectants. GASTROENTEROLOGY 1998;114:1287-1295

The role of sphingomyelin-derived second messengers in progesterone-induced reinitiation of the meiotic cell cycle of Xenopus laevis oocytes was investigated. A brief treatment of defolliculated oocytes with sphingomyelinase (Staphylococcus aureus) was sufficient to induce maturation as measured by H1 kinase activity and germinal vesicle breakdown (GVBD). Pretreatment with cycloheximide inhibited sphingomyelinase-induced GVBD demonstrating a requirement for protein synthesis. Microinjection of ceramide or sphingosine, potential products of sphingomyelin hydrolysis, were capable of inducing GVBD in the absence of hormone. Metabolic labeling studies suggested the conversion of sphingosine to ceramide was necessary for sphingosine-induced GVBD. Additionally, fumonisin b1, an inhibitor of sphingosine N-acyltransferase, blocked sphingosine-induced GVBD demonstrating that ceramide is the more proximal biologically active metabolite. Treatment of oocytes with progesterone, the physiological inducer of oocyte maturation, resulted in a time- and concentration-dependent increase in the mass of ceramide and decrease in the mass of sphingomyelin through activation of a Mg(2+)-dependent neutral sphingomyelinase. These observations suggest that the generation of ceramide from sphingomyelin is part of the signal transduction pathway activated in response to progesterone and that the increase in ceramide is likely to be functionally important in resumption of the meiotic cell cycle.

In clams, fertilization is followed by the prominent synthesis of two cyclins, A and B. During the mitotic cell cycles, the two cyclins are accumulated and then destroyed near the end of each metaphase. Newly synthesized cyclin B is complexed with a small set of other proteins, including a kinase that phosphorylates cyclin B in vitro. While both cyclins can act as general inducers of entry into M phase, the two are clearly distinguished by their amino acid sequences (70% nonidentity) and by their different modes of expression in oocytes and during meiosis. In contrast to cyclin A, which is stored solely as maternal mRNA, oocytes contain a stockpile of cyclin B protein, which is stored in large, rapidly sedimenting aggregates. Fertilization results in the release of cyclin B to a more disperse, soluble form. Since the first meiotic division in clams can proceed even when new protein synthesis is blocked, these results strongly suggest it is the fertilization-triggered unmasking of cyclin B protein that drives cells into meiosis I. We propose that the unmasking of maternal cyclin B protein allows it to interact with cdc2 protein kinase, which is also stored in oocytes, and that the formation of this cyclin B/cdc2 complex generates active M phase-promoting factor.

AbstractSexupara production in the pear root aphid, Eriosoma pyricolaBaker & Davidson, was closely associated with the cessation of shoot growth of its host in the field in irrigated and non-irrigated plots in two successive, but phenologically different years. Neither the environment nor the host plant were unfavorable at the time the sexuparae were formed, indicating that the aphid uses the host plant as a source of seasonal information.The nature of synchronization between active development of univoltine insects and trees is discussed. It is concluded that the initiation of dormancy in trees and diapause in insects is not likely to be synchronized by a common set of environmental factors. Either regulation of insect diapause by host trees is more common than is currently recognized, or environmental and age differences in tree growth have favored selection for obligate diapause.

The authors studied the cumulative probability of pregnancy for up to 4 consecutive embryo transfer (ET) cycles with ICSI performed for male factor. Transfers could be either fresh or frozen. The clinical pregnancy rate (PR) for the first 4 cycles were similar [44%(61/366); 31%(44/138); 45% (14/31); 44%(4/9)]. Delivery rates were also similar. There was a lower PR on the second retrieval vs. the first retrieval (47% vs. 29%), but this may be related to most of the second retrievals occurring in the second transfer cycle (67%,31/55); this may be explained by women who were poor responders and required another retrieval without a frozen ET. The majority of transfers in cycle 1 were fresh, whereas cycles 2-4 used primarily frozen-thawed embryos. These data should be helpful for patients requiring IVF with ICSI in deciding to continue with more IVF cycles or consider other options.