Comparison between different referral strategies for acute ischemic stroke patients in a hub-spoke emergency stroke network: a real-world experience in south-east Lazio.

AIM: To describe different referral strategies for acute ischemic stroke (AIS) patients in a Hub-Spoke emergency stroke network with their incidence, time metrics and related outcomes. METHODS: Referral paradigms were defined as follows: primary transfer to the comprehensive stroke center (CSC) from a remote region, called mothership (MS); secondary transfer to the CSC from a primary stroke center where intravenous thrombolysis was available, called drip and ship (DS); secondary transfer to the CSC from a community hospital where no reperfusion therapy was available, called ship and drip (SD); primary transfer to the CSC from its catchment area, called direct CSC (dCSC). RESULTS: Among 517 anterior circulation AIS patients treated with mechanical thrombectomy between 2015 and 2020, 16.6% of them were SD, in addition to the well-known referral paradigms of MS (21.8%) and DS (18.1%). This rate grew to 30% when only patients whose place of onset was outside the CSC catchment area were considered. In the SD group, onset to CSC and onset to groin were significantly longer (178±80 min vs. 102±60 min, p<0.001, and 277±77 min vs. 211±61 min, p<0.001, respectively), and the risk of any intracranial hemorrhage (ICH) was significantly higher (OR: 2.514; 95%CI: 1.18-5.35, p=0.017) compared to MS. CONCLUSION: In this hub-spoke stroke network, a high proportion of SD paradigm was found, which was associated with longer times to treatment and higher rates of any ICH. A closer cooperation between hospital stroke physicians, national health system staff, and paramedics is warranted to identify the most appropriate referral strategy for each patient.

Impact of A1 Asymmetry on the Woven EndoBridge Device in Anterior Communicating Artery Aneurysms.

BACKGROUND AND PURPOSE: Woven EndoBridge (WEB) devices are increasingly used to treat intracranial aneurysms. A1 asymmetry contributes to anterior communicating artery aneurysm formation and to treatment instability after coiling. We sought to evaluate whether A1 asymmetry had an impact on angiographic outcome in anterior communicating artery aneurysms treated with the WEB. MATERIALS AND METHODS: Anterior communicating artery aneurysms treated between July 2012 and July 2020 with the WEB from an institutional review board-approved database were reviewed. A1 asymmetry was categorized as the following: absence of the A1 segment on 1 side (unilateral A1) versus bilateral A1. Univariate and multivariable analyses assessed independent predictors of adequate (WEB Occlusion Scale A, B, and C) and complete occlusion (WEB Occlusion Scale A and B). RESULTS: Forty-eight individual aneurysms (47 patients) were included in the final analysis, of which 16 (33%) were acutely ruptured. The mean size was 6.5 (SD, 2.2) mm. Adequate and complete occlusion was achieved in 33 (69%) and 30 (63%) cases, respectively. Unilateral A1 was associated with significantly higher rates of adequate (92% versus 60% for bilateral A1; P = .03) and complete occlusion (92% versus 50% for bilateral A1; P < .01). Multivariable logistic regression confirmed unilateral A1 as an independent predictor of both adequate (OR = 10.6; 95% CI, 1.6-220.7; P = .04) and complete occlusion (OR = 9.5, 95% CI, 1.5-190.2; P = .04. A sensitivity analysis comparing unilateral "functional" A1 with bilateral "functional" A1 showed similar results. WEB shape modification was not influenced by the unilateral A1 configuration (P = .70). CONCLUSIONS: Anterior communicating artery aneurysms with a unilateral A1 configuration treated with WEB devices are associated with better angiographic outcome than those with bilateral A1. This finding supports the hypothesis that WEB devices are resistant to unilateral flow in the aneurysm as opposed to coils.

Functional redundancy and compensation: Deletion of multiple murine Crisp genes reveals their essential role for male fertility.

Mammalian Cysteine-RIch Secretory Protein (CRISP) family includes four members present in sperm and reported to regulate Ca2+ channels and fertilization. Based on our previous observations using single knockouts models and suggesting the existence of functional compensation among CRISP proteins, we investigated their relevance for male fertility by generating multiple Crisp gene mutants by CRISPR/Cas9 technology. Whereas targeting of Crisp1 and Crisp3 yielded subfertile males with early embryo developmental defects, the same deletion in zygotes from fertile Crisp2-/- .Crisp4-/- mice led to the generation of both triple and quadruple knockout mice exhibiting a complete or severe disruption of male fertility due to a combination of sperm transport, fertilization, and embryo developmental defects linked to intracellular Ca2+ dysregulation. These observations reveal that CRISP proteins are essential for male fertility and organize in functional modules that contribute distinctly to fertility success, bringing insights into the mechanisms underlying functional redundancy/compensation in protein families and emphasizing the importance of generating multiple and not just single knockout which might be masking the true functional relevance of family genes.

Carotid Stenting and Mechanical Thrombectomy in Patients with Acute Ischemic Stroke and Tandem Occlusions: Antithrombotic Treatment and Functional Outcome.

BACKGROUND AND PURPOSE: There is no consensus on the optimal antithrombotic medication for patients with acute ischemic stroke with anterior circulation tandem occlusions treated with emergent carotid stent placement and mechanical thrombectomy. The identification of factors influencing hemorrhagic risks can assist in creating appropriate therapeutic algorithms for such patients. This study aimed to investigate the impact of medical therapy on functional and safety outcomes in patients treated with carotid stent placement and mechanical thrombectomy for tandem occlusions. MATERIALS AND METHODS: A multicenter retrospective study on prospectively collected data was conducted. Only patients treated with carotid stent placement and mechanical thrombectomy for tandem occlusions of the anterior circulation were included. Univariate and multivariate analyses were performed on preprocedural, procedural, and postprocedural variables to assess factors influencing clinical outcome, symptomatic intracranial hemorrhage, stent patency, and successful intracranial vessel recanalization. RESULTS: Ninety-five patients with acute ischemic stroke and tandem occlusions were included. Good clinical outcome (mRS ≤ 2) at 3 months was reached by 33 (39.3%) patients and was associated with baseline ASPECTS ≥ 8 (OR = 1.53; 95% CI, 1.16-2.00), ≤2 mechanical thrombectomy attempts (OR = 0.71; 95% CI, 0.55-0.99), and the absence of symptomatic intracranial hemorrhage (OR = 0.13; 95% CI , 0.03-0.51). Symptomatic intracranial hemorrhage was associated with a higher amount of intraprocedural heparin, ASPECTS ≤ 7, and ≥3 mechanical thrombectomy attempts. No relationships among types of acute antiplatelet regimen, intravenous thrombolysis, and symptomatic intracranial hemorrhage were observed. Patients receiving dual-antiplatelet therapy after hemorrhagic transformation had been ruled out on 24-hour CT were more likely to achieve functional independence and had a lower risk of symptomatic intracranial hemorrhage. CONCLUSIONS: During carotid stent placement and mechanical thrombectomy for tandem occlusion treatment, higher intraprocedural heparin dosage (≥3000 IU) increased symptomatic intracranial hemorrhage risk when the initial ASPECTS was ≤7, and mechanical thrombectomy needs more than one passage for complete recanalization. Antiplatelets antiplatelets use were safe, and dual-antiaggregation therapy was related to better functional outcomes.

Association between high-fat diet feeding and male fertility in high reproductive performance mice.

The increasing worldwide prevalence of metabolic syndrome (MetS), especially in younger populations, is a risk factor for fertility disorders. However, a direct correlation of MetS with male infertility still remains unclear. In this work, we evaluated whether MetS has a negative impact on fertility of hybrid male mice with high reproductive performance. To induce a MetS-like condition, (C57BL/6xBALB/c) F1 male mice were fed a high-fat diet (HFD, 30% fat) for 19 weeks, while controls received a normal-fat diet (NFD, 6% fat). HFD-fed animals exhibited increased body weight, hypercholesterolemia, hyperglycemia and glucose intolerance. In vivo fertilisation assays performed along the treatment period showed no differences in fertilisation nor in vitro embryo development rates between groups. While testicular weight and morphology were similar in both groups, HFD-fed mice presented lighter epididymides and higher amounts of gonadal fat. Moreover, sperm count was lower in HFD-fed mice, despite normal sperm viability, morphology, motility or acrosome reaction. Finally, no differences were observed in in vitro fertilisation rates between groups. In summary, although HFD feeding altered some reproductive parameters, it did not impair male fertility in high performance breeders suggesting the possibility that a fertility impairment could be the result of the cumulative combination of environmental and/or genetic factors.

Lymphographic-Like Technique for the Treatment of Microcystic Lymphatic Malformation Components of <3 mm.

BACKGROUND AND PURPOSE: The treatment of microcystic lymphatic malformations remains challenging. Our aim was to describe the lymphographic-like technique, a new technique of slow bleomycin infusion for the treatment of microcyst components of <3 mm, performed at our institution. MATERIALS AND METHODS: A retrospective analysis of a prospectively collected lymphatic malformation data base was performed. Patients with at least 1 microcystic lymphatic malformation component demonstrated on MR imaging treated by lymphographic-like technique bleomycin infusion were included in the study. Patient interviews and MR imaging were performed to assess subjective and objective (microcystic lymphatic malformation size decrease of >30%) clinical improvement, respectively. Patients were reviewed 3 months after each sclerotherapy session. Lymphographic-like technique safety and efficacy were assessed. RESULTS: Between January 2012 and July 2016, sixteen patients (5 males, 11 females; mean age, 15 years; range, 1-47 years) underwent the bleomycin lymphographic-like technique for microcystic lymphatic malformations. Sixty sclerotherapy sessions were performed, with a mean of 4 sessions per patient (range, 1-8 sessions) and a mean follow-up of 26 months (range, 5-58 months). We observed no major and 3 minor complications: 1 eyelid infection, 1 case of severe postprocedural nausea and vomiting, and 1 case of skin discoloration. One patient was lost to follow-up. Overall MR imaging objective improvement was observed in 5/16 (31%) patients; overall improvement of clinical symptoms was obtained in 93% of treated patients. CONCLUSIONS: The bleomycin lymphographic-like technique for microcystic lymphatic malformations is safe and feasible with objective improvement in about one-third of patients. MR signal intensity changes after the lymphographic-like technique are associated with subjective improvement of the patient's symptoms.

Large Basilar Apex Aneurysms Treated with Flow-Diverter Stents.

BACKGROUND AND PURPOSE: The treatment of wide-neck, large basilar apex aneurysms is challenging with either an endovascular or a surgical approach. The aim of the present study was to report our experience treating basilar apex aneurysms with flow-diverter stents and to evaluate their efficacy and safety profile in this specific anatomic condition. MATERIALS AND METHODS: We retrospectively analyzed data from all consecutive patients treated with flow-diverter stents at our institution between January 2011 and January 2015. Patients with large basilar apex aneurysms treated with a flow-diverter stent were included in the study. Clinical presentations, technical details, intra- and perioperative complications, and clinical and angiographic outcomes were recorded, with a midterm follow-up. RESULTS: Of the 175 aneurysms treated with flow-diverter stents at our institution, 5 patients (2 women and 3 men; age range, 44-58 years) received flow-diverter stent for basilar apex aneurysms. The mean follow-up after stent deployment was 21 months (range, 15-24 months). One patient died on day 31 from an early postprocedural midbrain hemorrhage. One patient had a right cerebellar hemispheric ischemic lesion with a transient cerebellar syndrome resolved within 24 hours without neurologic sequelae at the latest follow-up. The mRS was 0 in 4 patients and 6 in 1 patient at last follow-up. CONCLUSIONS: Flow diversion is a feasible technique with an efficacy demonstrated at a midterm follow-up, especially in the case of basilar apex aneurysm recurrences after previous endovascular treatments. Concern about its safety profile still exists.

Fertilization defects in sperm from Cysteine-rich secretory protein 2 (Crisp2) knockout mice: implications for fertility disorders.

STUDY HYPOTHESIS: We hypothesize that fertility disorders in patients with aberrant expression of Cysteine-RIch Secretory Protein 2 (CRISP2) could be linked to the proposed functional role of this protein in fertilization. STUDY FINDING: Our in vivo and in vitro observations reveal that Crisp2-knockout mice exhibit significant defects in fertility-associated parameters under demanding conditions, as well as deficiencies in sperm fertilizing ability, hyperactivation development and intracellular Ca(2+) regulation. WHAT IS KNOWN ALREADY: Testicular CRISP2 is present in mature sperm and has been proposed to participate in gamete fusion in both humans and rodents. Interestingly, evidence in humans shows that aberrant expression of CRISP2 is associated with male infertility. STUDY DESIGN, SAMPLES/MATERIALS, METHODS: A mouse line carrying a deletion in the sixth exon of the Crisp2 gene was generated. The analyses of the reproductive phenotype of Crisp2(-/-) adult males included the evaluation of their fertility before and after being subjected to unilateral vasectomy, in vivo fertilization rates obtained after mating with either estrus or superovulated females, in vitro sperm fertilizing ability and different sperm functional parameters associated with capacitation such as tyrosine phosphorylation (by western blot), acrosome reaction (by Coomassie Blue staining), hyperactivation (by computer-assisted sperm analysis) and intracellular Ca(2+) levels (by flow cytometry). MAIN RESULTS AND THE ROLE OF CHANCE: Crisp2(-/-) males presented normal fertility and in vivo fertilization rates when mated with estrus females. However, the mutant mice showed clear defects in those reproductive parameters compared with controls under more demanding conditions, i.e. when subjected to unilateral vasectomy to reduce the number of ejaculated sperm (n = 5; P< 0.05), or when mated with hormone-treated females containing a high number of eggs in the ampulla (n ≥ 5; P< 0.01). In vitro fertilization studies revealed that Crisp2(-/-) sperm exhibited deficiencies to penetrate the egg vestments (i.e. cumulus oophorus and zona pellucida) and to fuse with the egg (n ≥ 6; P< 0.01). Consistent with this, Crisp2-null sperm showed lower levels of hyperactivation (n = 7; P< 0.05), a vigorous motility required for penetration of the egg coats, as well as a dysregulation in intracellular Ca(2+) levels associated with capacitation (n = 5; P< 0.001). LIMITATIONS, REASONS FOR CAUTION: The analysis of the possible mechanisms involved in fertility disorders in men with abnormal expression of CRISP2 was carried out in Crisp2 knockout mice due to the ethical and technical problems inherent to the use of human gametes for fertilization studies. WIDER IMPLICATIONS OF THE FINDINGS: Our findings in mice showing that Crisp2(-/-) males exhibit fertility and fertilization defects under demanding conditions support fertilization defects in sperm as a mechanism underlying infertility in men with aberrant expression of CRISP2. Moreover, our observations in mice resemble the situation in humans where fertility disorders can or cannot be detected depending on the accumulation of own individual defects or the fertility status of the partner. Finally, the fact that reproductive defects in mice are masked by conventional mating highlights the need of using different experimental approaches to analyze male fertility. STUDY FUNDING AND COMPETING INTERESTS: This study was supported by the World Health Organization (H9/TSA/037), the National Research Council of Argentina (PIP 2009-290), the National Agency for Scientific and Technological Promotion of Argentina (PICT 2011, 2023) and the Rene Baron Foundation to P.S.C. and by the MEXT of Japan to M.I. The authors declare that there are no conflicts of interest.

Isthmocele in a retroflexed uterus: a report of an unrecognized case.

The term "isthmocele" refers to a niche on the anterior wall of the uterine isthmus or of the cervical canal at the site of a previous cesarean delivery scar. Such anatomic defect can cause many gynecologic sequelae that only recently have being identified and described. Hysteroscopy is commonly considered the gold standard for the diagnosis and also for the treatment, at least in the case of defects of small size. The authors described the case of a 37-year-old woman who underwent a cesarean section (CS) seven years before, with a long lasting history of menstrual irregularities, and pelvic pain increasing during menstruation at the hypogastric level. Magnetic resonance imaging (MRI) showed an exceptionally large isthmocele on the anterior wall of a retroflexed uterus which was otherwise misinterpreted as the uterine cavity filled with menstrual blood during a previous hysteroscopy (HSC). Although exceptional, this case highlights the possibility that a large sized isthmocele in a retroflexed uterus could be misinterpreted as the uterine cavity filled by menstrual blood at HSC. In this case MRI definitely clarified the diagnosis.

Evidence for the involvement of proline-rich tyrosine kinase 2 in tyrosine phosphorylation downstream of protein kinase A activation during human sperm capacitation.

Sperm capacitation involves an increase in intracellular Ca(2+) concentration as well as in protein kinase A (PKA)-dependent protein tyrosine (Tyr) phosphorylation. Interestingly, in humans, a decrease in extracellular Ca(2+) concentration ([Ca(2+)]e) during capacitation induces an increase in Tyr phosphorylation indicating the complexity of Ca(2+) signaling during this process. In view of this, in the present study we further investigated the Ca(2+)-mediated signaling pathways implicated in Tyr phosphorylation during human sperm capacitation. Results revealed that sperm incubation in a medium without added Ca(2+) (⊖ Ca(2+)) increased Tyr phosphorylation but did not modify PKA-mediated phosphorylation. Moreover, inhibition of either PKA or Src family kinase signaling cascades in ⊖ Ca(2+) down-regulated both PKA substrate and Tyr phosphorylations, indicating that the [Ca(2+)]e effects on Tyr phosphorylation depend on PKA targets. Inhibition of calmodulin or Ser/Thr protein phosphatase 2B also increased Tyr phosphorylation without affecting PKA-mediated phosphorylation, supporting the potential role of these Ca(2+) downstream effectors in the increase in Tyr phosphorylation observed in ⊖ Ca(2+). Experiments aimed to identify the kinase responsible for these observations revealed the presence of proline-rich tyrosine kinase 2 (PYK2), a focal adhesion kinase (FAK) family member, in human sperm, and the use of PF431396, an FAK inhibitor, supported the involvement of PYK2 in Tyr phosphorylation downstream of PKA activation. Results also showed that PYK2 was activated in ⊖ Ca(2+) as well as during capacitation and that PF431396 affected capacitated sperm motility, acrosome reaction and ability to penetrate both mouse cumulus matrix and zona-free hamster eggs. Together, our observations support PYK2 as an intermediary component of Ca(2+) signaling between PKA-mediated and Tyr phosphorylations that is required for achieving functional human sperm capacitation.

Functional human sperm capacitation requires both bicarbonate-dependent PKA activation and down-regulation of Ser/Thr phosphatases by Src family kinases.

In all mammalian species studied so far, sperm capacitation correlates with an increase in protein tyrosine (Tyr) phosphorylation mediated by a bicarbonate-dependent cAMP/protein kinase A (PKA) pathway. Recent studies in mice revealed, however, that a Src family kinase (SFK)-induced inactivation of serine/threonine (Ser/Thr) phosphatases is also involved in the signaling pathways leading to Tyr phosphorylation. In view of these observations and with the aim of getting a better understanding of the signaling pathways involved in human sperm capacitation, in the present work we investigated the involvement of both the cAMP/PKA and SFK/phosphatase pathways in relation to the capacitation state of the cells. For this purpose, different signaling events and sperm functional parameters were analyzed as a function of capacitation time. Results revealed a very early bicarbonate-dependent activation of PKA indicated by the rapid (1 min) increase in both phospho-PKA substrates and cAMP levels (P < 0.05). However, a complete pattern of Tyr phosphorylation was detected only after 6-h incubation at which time sperm exhibited the ability to undergo the acrosome reaction (AR) and to penetrate zona-free hamster oocytes. Sperm capacitated in the presence of the SFK inhibitor SKI606 showed a decrease in both PKA substrate and Tyr phosphorylation levels, which was overcome by exposure of sperm to the Ser/Thr phosphatase inhibitor okadaic acid (OA). However, OA was unable to induce phosphorylation when sperm were incubated under PKA-inhibitory conditions (i.e. in the absence of bicarbonate or in the presence of PKA inhibitor). Moreover, the increase in PKA activity by exposure to a cAMP analog and a phosphodiesterase inhibitor did not overcome the inhibition produced by SKI606. Whereas the presence of SKI606 during capacitation produced a negative effect (P < 0.05) on sperm motility, progesterone-induced AR and fertilizing ability, none of these inhibitions were observed when sperm were exposed to SKI606 and OA. Interestingly, different concentrations of inhibitors were required to modulate human and mouse capacitation revealing the species specificity of the molecular mechanisms underlying this process. In conclusion, our results describe for the first time the involvement of both PKA activation and Ser/Thr phosphatase down-regulation in functional human sperm capacitation and provide convincing evidence that early PKA-dependent phosphorylation is the convergent regulatory point between these two signaling pathways.

Endovascular management of acute stroke.

Ischemic stroke is the third leading cause of death and most common cause of permanent disability in industrialized nations. Eighty-five percent of strokes are ischemic in nature, with an associated mortality between 53% and 92%. The focus of treatment for acute stroke starts with prompt and accurate diagnosis of ischemic brain tissue at risk, followed by time sensitive delivery of therapy that effectively and safely restores flow to that vascular territory. Time-dependent reperfusion therapy is the only proven treatment for Acute Ischemic Stroke. In this paper, we review the clinical and imaging factors that are relevant to guide endovascular treatment decisions; the different approaches of stroke therapy and the devices used with the goal of obtaining the most rapid and complete recanalization possible, while minimizing vascular damage and hemorrhagic complications. It is paid particular attention to indications and outcomes of the different endovascular stroke therapy devices use, as defined in major clinical trials or current clinical practice. Anterior circulation strokes represent the primary focus of this review.

Endovascular radiofrequency renal denervation in treating refractory arterial hypertension: a preliminary experience.

PURPOSE: This study was done to investigate the efficacy and safety of percutaneous renal denervation with the Symplicity catheter for reducing blood pressure in patients with essential hypertension resistant to medical therapy (systolic blood pressure >160 mmHg despite the use of three or more antihypertensive drugs, including a diuretic). MATERIALS AND METHODS: In September 2010, five patients affected by essential hypertension resistant to medical therapy were treated. All patients were studied by computed tomography angiography (CTA) of the renal arteries before the procedure and underwent follow-up at 30 and 60 days with colour Doppler ultrasound (CDUS) with evaluation of resistive index, glomerular filtration rate (GFR), 24-h blood pressure and serum catecholamine concentration. Student's t test was used to assess the effectiveness of the procedure in lowering blood pressure. RESULTS: In treated patients, mean blood pressure at baseline was 171/100 mmHg [standard deviation (SD) ± 8/10]; mean GFR was 91.6 ml/min/1.73 m(2) (SD ± 15). Blood pressure after the procedure was reduced by -18/-5 and -13/-10 mmHg at 30 and 60 days, respectively, with a mean medication reduction of 3.6. No complications occurred during the intra- or periprocedural period or during short-term follow-up. CONCLUSIONS: The Symplicity system proved to be efficacious and without serious adverse events in reducing blood pressure and antihypertensive medication use in patients affected by essential hypertension resistant to medical therapy. Although encouraging, our data are preliminary and need to be validated by larger prospective randomised studies.

Molecular mechanisms involved in gamete interaction: evidence for the participation of cysteine-rich secretory proteins (CRISP) in sperm-egg fusion.

Epididymal protein DE and testicular protein Tpx-1 are two cysteine-rich secretory proteins also known as CRISP-1 and CRISP-2, respectively. DE/ CRISP-1 is localised on the equatorial segment of acrosome-reacted sperm and participates in rat gamete fusion through its binding to egg-complementary sites. Recent results using bacterially-expressed recombinant fragments of DE as well as synthetic peptides revealed that the ability of DE to bind to the egg surface and inhibit gamete fusion resides in a region of 12 amino acids corresponding to an evolutionary conserved motif of the CRISP family (Signature 2). Given the high degree of homology between DE/CRISP-1 and Tpx-1/CRISP-2, we also explored the potential participation of the testicular intra-acrosomal protein in gamete fusion. Results showing the ability of recombinant Tpx-1 to bind to the surface of rat eggs (evaluated by indirect immunofluorescence) and to significantly inhibit zona-free egg penetration, support the participation of this protein in gamete fusion through its interaction with egg-binding sites. Interestingly, rat Tpx-1 exhibits only two substitutions in Signature 2 when compared to this region in DE. Together, these results provide evidence for the involvement of both epididymal DE/CRISP-1 and testicular Tpx-1/CRISP-2 in gamete fusion suggesting the existence of a functional cooperation between homologue molecules as a mechanism to ensure the success of fertilisation.

Studies on the participation of epididymal sperm protein DE/CRISP-1 in egg activation.

Protein DE (32 kDa) associates with sperm during epididymal maturation and participates in sperm-egg fusion through its binding to complementary sites on the egg surface. In the present work we investigated the participation of DE in two mechanisms probably involved in egg activation: the ability of DE to trigger activation by its interaction with the binding sites on the egg surface (receptor model) and its ability to regulate intracellular calcium channels (sperm factor model). The incubation of eggs with DE did not promote activation parameters such as calcium oscillations or meiosis resumption. Secondly, microinjection of DE into eggs was ineffective in either eliciting calcium release or modifying oscillations induced by an activating sperm extract. Together, these results argue against the participation of DE in egg activation, restricting the activity of this protein and its egg binding sites to the sperm-egg fusion process.

Molecular mechanisms involved in mammalian gamete fusion.

Fusion between gametes is a key event in the fertilization process involving the interaction of specific domains of the sperm and egg plasma membranes. During recent years, efforts have been made toward the identification of the specific molecular components involved in this event. The present work will focus on the best characterized candidates for mediating gamete membrane fusion in mammals. These molecules include members of the ADAM (a disintegrin and a metalloprotease domain) family, i.e., testicular proteins fertilin alpha, fertilin beta, and cyritestin, which are thought to interact with integrins in the egg plasma membrane through their disintegrin domains, and a member of the cysteine-rich secretory proteins (CRISP) family, i.e., epididymal protein DE, which participates in an event subsequent to sperm-egg binding and leading to fusion through specific complementary sites localized on the fusogenic area of the egg surface. The identification and characterization of these molecules will contribute not only to a better understanding of the molecular mechanisms underlying mammalian sperm-egg fusion but also to the development of new methods for both fertility regulation and diagnosis and treatment of human infertility.