Vector-apodizing phase plate coronagraph: design, current performance, and future development [Invited].

Over the last decade, the vector-apodizing phase plate (vAPP) coronagraph has been developed from concept to on-sky application in many high-contrast imaging systems on 8 m class telescopes. The vAPP is a geometric-phase patterned coronagraph that is inherently broadband, and its manufacturing is enabled only by direct-write technology for liquid-crystal patterns. The vAPP generates two coronagraphic point spread functions (PSFs) that cancel starlight on opposite sides of the PSF and have opposite circular polarization states. The efficiency, that is, the amount of light in these PSFs, depends on the retardance offset from a half-wave of the liquid-crystal retarder. Using different liquid-crystal recipes to tune the retardance, different vAPPs operate with high efficiencies (${\gt}96\%$) in the visible and thermal infrared (0.55 µm to 5 µm). Since 2015, seven vAPPs have been installed in a total of six different instruments, including Magellan/MagAO, Magellan/MagAO-X, Subaru/SCExAO, and LBT/LMIRcam. Using two integral field spectrographs installed on the latter two instruments, these vAPPs can provide low-resolution spectra (${\rm{R}} \sim 30$) between 1 µm and 5 µm. We review the design process, development, commissioning, on-sky performance, and first scientific results of all commissioned vAPPs. We report on the lessons learned and conclude with perspectives for future developments and applications.

Metabolic improvement in obese patients after duodenal-jejunal exclusion is associated with intestinal microbiota composition changes.

BACKGROUND: Intestinal microbiota have been suggested to play an important role in the pathogenesis of obesity and type 2 diabetes. Bariatric surgery improves both conditions and has been associated with changes in intestinal microbiota composition. We investigated the effect of a nonsurgical bariatric technique on intestinal microbiota composition in relation to metabolic improvement. METHODS: Seventeen patients with obesity and type 2 diabetes were treated with the nonsurgical duodenal-jejunal bypass liner, which excludes the proximal 60 cm small intestine from food. Fecal samples as well as metabolic parameters reflecting obesity and type 2 diabetes were obtained from the patients at baseline, after 6 months with the device in situ, and 6 months after explantation. RESULTS: After 6 months of treatment, both obesity and type 2 diabetes had improved with a decrease in weight from 106.1 [99.4-123.5] to 97.4 [89.4-114.0] kg and a decrease in HbA1c from 8.5% [7.6-9.2] to 7.2% [6.3-8.1] (both p < 0.05). This was paralleled by an increased abundance of typical small intestinal bacteria such as Proteobacteria, Veillonella, and Lactobacillus spp. in feces. After removal of the duodenal-jejunal bypass liner, fecal microbiota composition was similar to that observed at baseline, despite persistent weight loss. CONCLUSION: Improvement of obesity and type 2 diabetes after exclusion of the proximal 60 cm small intestine by treatment with a nonsurgical duodenal-jejunal bypass liner may be promoted by changes in fecal microbiota composition.

The "omics" of human male infertility: integrating big data in a systems biology approach.

Spermatogenesis is a complex process in which >2300 genes are temporally and spatially regulated to form a terminally differentiated sperm cell that must maintain the ability to contribute to a totipotent embryo which can successfully differentiate into a healthy individual. This process is dependent on fidelity of the genome, epigenome, transcriptome, and proteome of the spermatogonia, supporting cells, and the resulting sperm cell. Infertility and/or disease risk may increase in the offspring if abnormalities are present. This review highlights the recent advances in our understanding of these processes in light of the "omics revolution". We briefly review each of these areas, as well as highlight areas of future study and needs to advance further.

Clearing of psoriasis documented by laser Doppler perfusion imaging contrasts remaining elevation of dermal expression levels of CD31.

BACKGROUND: Vascular modifications represent a key feature in psoriatic plaques. Previous research with Laser Doppler Perfusion Imaging (LDPI) revealed a remarkable heterogeneity in the cutaneous perfusion within homogenous-appearing psoriatic lesions. Insights in the relation between perfusion during treatment and related biological changes are lacking. OBJECTIVES: To study the effect of calcipotriol-betamethasone dipropionate ointment on the microcirculation and the expression levels of immunohistochemical markers in psoriatic lesions compared to the distant uninvolved skin. METHODS: Psoriatic lesions of fourteen patients were treated once a day during 8 weeks. Clinical SUM scores and the perfusion intensity by means of LDPI were assessed every 2 weeks. After 8 weeks, a biopsy from the target lesion and one from the distant uninvolved skin were taken and stained for psoriasis-related markers, like IL-17 and CD31. RESULTS: After 8 weeks, seven patients reached a SUM score of 0 or 1, and were classified as good-responders. The other patients were classified moderate-responders. The perfusion intensity decreased in all lesions during therapy. In the good-responders, all investigated psoriasis-related proteins within the treated lesions reached the expression level found within the distant uninvolved skin. The expression of CD31, however, was significantly higher in the treated lesions as compared to the distant uninvolved skin (p = 0.0156). In the moderate responders, almost all expression levels remained significantly elevated compared to the uninvolved skin. CONCLUSIONS: In the skin of good-responders the expression of dermal CD31(+) endothelium remains significantly elevated within the treated lesions compared with the distant uninvolved skin, whereas a marked reduction in the perfusion intensity and SUM score was found. This indicates that clinical improvement might outrun endothelial changes.

Effect of a multidisciplinary lifestyle intervention on body composition in people with osteoarthritis: Secondary analysis of the "Plants for Joints" randomized controlled trial.

Objective: The Plants for Joints (PFJ) intervention significantly improved pain, stiffness, and physical function, and metabolic outcomes, in people with metabolic syndrome-associated osteoarthritis (MSOA). This secondary analysis investigated its effects on body composition. Method: In the randomized PFJ study, people with MSOA followed a 16-week intervention based on a whole-food plant-based diet, physical activity, and stress management, or usual care. For this secondary analysis, fat mass, muscle mass, and bone mineral density were measured using dual-energy X-ray absorptiometry (DEXA) for all participants. Additionally, in a subgroup (n â€‹= â€‹32), hepatocellular lipid (HCL) content and composition of visceral adipose tissue (VAT) were measured using magnetic resonance spectroscopy (MRS). An intention-to-treat analysis with a linear-mixed model adjusted for baseline values was used to analyse between-group differences. Results: Of 66 people randomized, 64 (97%) completed the study. The PFJ group experienced significant weight loss (-5.2 â€‹kg; 95% CI -6.9, -3.6) compared to controls, primarily from fat mass reduction (-3.9 â€‹kg; 95% CI -5.3 to -2.5). No significant differences were found in lean mass, muscle strength, or bone mineral density between groups. In the subgroup who underwent MRI scans, the PFJ group had a greater reduction in HCL (-6.5%; 95% CI -9.9, 3.0) compared to controls, with no observed differences in VAT composition. Conclusion: The PFJ multidisciplinary intervention positively impacted clinical and metabolic outcomes, and appears to significantly reduce body fat, including liver fat, while preserving muscle mass and strength.

Precision assessment of bowel motion quantification using 3D cine-MRI for radiotherapy.

Objective. The bowel is an important organ at risk for toxicity during pelvic and abdominal radiotherapy. Identifying regions of high and low bowel motion with MRI during radiotherapy may help to understand the development of bowel toxicity, but the acquisition time of MRI is rather long. The aim of this study is to retrospectively evaluate the precision of bowel motion quantification and to estimate the minimum MRI acquisition time.Approach. We included 22 gynaecologic cancer patients receiving definitive radiotherapy with curative intent. The 10 min pre-treatment 3D cine-MRI scan consisted of 160 dynamics with an acquisition time of 3.7 s per volume. Deformable registration of consecutive images generated 159 deformation vector fields (DVFs). We defined two motion metrics, the 50th percentile vector lengths (VL50) of the complete set of DVFs was used to measure median bowel motion. The 95th percentile vector lengths (VL95) was used to quantify high motion of the bowel. The precision of these metrics was assessed by calculating their variation (interquartile range) in three different time frames, defined as subsets of 40, 80, and 120 consecutive images, corresponding to acquisition times of 2.5, 5.0, and 7.5 min, respectively.Main results. For the full 10 min scan, the minimum motion per frame of 50% of the bowel volume (M50%) ranged from 0.6-3.5 mm for the VL50 motion metric and 2.3-9.0 mm for the VL95 motion metric, across all patients. At 7.5 min scan time, the variation in M50% was less than 0.5 mm in 100% (VL50) and 95% (VL95) of the subsets. A scan time of 5.0 and 2.5 min achieved a variation within 0.5 mm in 95.2%/81% and 85.7%/57.1% of the subsets, respectively.Significance. Our 3D cine-MRI technique quantifies bowel loop motion with 95%-100% confidence with a precision of 0.5 mm variation or less, using a 7.5 min scan time.

Impairment in work and activities of daily life in patients with psoriasis: results of the prospective BioCAPTURE registry.

Background: Little is known about the extent of impairments in work and activities of daily life (ADL) in patients with psoriasis, and the influence of contextual factors such as disease-related characteristics and treatment. Therefore, this study aimed to assess these impairments in patients with psoriasis who started using biologicals/small molecule inhibitors.Methods: Using data from the prospective BioCAPTURE registry, we collected patient, disease, and treatment parameters, as well as work/ADL impairments at baseline, 6 and 12 months. Changes in impairment parameters and correlations between impairment and patient/disease characteristics were assessed using generalized estimating equations.Results: We included 194 patients in our analysis. After biological initiation, disease activity decreased significantly (PASI 11.2 at baseline versus 3.9 at 12 months, p < 0.001). Work-for-pay in this cohort was lower than in the Dutch general population (53% versus 67%, p = 0.01). In patients who had work-for-pay, presenteeism improved over time (5% at baseline versus 0% at 12 months, p = 0.04). Up to half of the patients reported impairments in ADL, which did not change over time. Associations between impairments and contextual factors varied, but all impairments were associated with worse mental/physical general functioning.Conclusion: Patients with psoriasis using biologicals are less likely to have work-for-pay. Treatment improves the work productivity of employed patients, but we were unable to detect changes in ADL performance.

Correlation between male age, WHO sperm parameters, DNA fragmentation, chromatin packaging and outcome in assisted reproduction technology.

In the human, male ageing results in reproductive hormonal and cellular changes that can influence semen quality (volume, motility, concentration and morphology) and ultimately result in a reduced fertilising capacity and a longer 'time to pregnancy' for ageing men as well as an increased risk for miscarriage. This prospective cohort study of 278 patients undergoing a first in vitro fertilisation or intracytoplasmic sperm injection treatment was undertaken to examine whether patient's age was reflected in sperm motility, concentration, morphology as well as in DNA fragmentation (DFI) and immature chromatin (unprocessed nuclear proteins and/or poorly condensed chromatin) as measured by the sperm chromatin structure assay. This study also investigated the possible influence of male age (after correcting for female age) on their fertilising capacity, on obtaining a pregnancy and a healthy baby at home. Logistic regression analysis did not reveal any male age-related influences on sperm parameters like concentration, motility or morphology. No significant male age-related increase in DFI or immature chromatin was demonstrable for these patients. Elevated male age, after correcting for female age, was not related to lower fertilisation rates or significant decreases in the chance for a healthy baby at home.

Simultaneous assessment of colon motility in children with functional constipation by cine-MRI and colonic manometry: a feasibility study.

BACKGROUND: Colonic manometry is the current reference standard for assessing colonic neuromuscular function in children with intractable functional constipation (FC). Recently, cine magnetic resonance imaging (cine-MRI) has been proposed as a non-invasive alternative. We compared colonic motility patterns on cine-MRI with those obtained by manometry in children, by stimulating high-amplitude propagating contractions (HAPCs) with bisacodyl under manometric control while simultaneously acquiring cine-MRI. METHODS: After Institutional Review Board approval, adolescents with FC scheduled to undergo colonic manometry were included. A water-perfused 8-lumen catheter was used for colonic manometry recordings. After an intraluminal bisacodyl infusion, cine-MRI sequences of the descending colon were acquired for about 30 min simultaneously with colonic manometry. Manometry recordings were analysed for HAPCs. MRI images were processed with spatiotemporal motility MRI techniques. The anonymised motility results of both techniques were visually compared for the identification of HAPCs in the descending colon. RESULTS: Data regarding six patients (three males) were analysed (median age 14 years, range 12-17). After bisacodyl infusion, three patients showed a total of eleven HAPCs with colonic manometry. Corresponding cine-MRI recorded high colonic activity during two of these HAPCs, minimal activity during seven HAPCs, while two HAPCs were not recorded. In two of three patients with absent HAPCs on manometry, colonic activity was recorded with cine-MRI. CONCLUSIONS: Simultaneous acquisition of colonic cine-MRI and manometry in children with FC is feasible. Their motility results did not completely overlap in the identification of HAPCs. Research is needed to unravel the role of cine-MRI in this setting.

Additively manufactured space-filling meta-implants.

The unprecedented properties of meta-biomaterials could pave the way for the development of life-lasting orthopedic implants. Here, we used non-auxetic meta-biomaterials to address the shortcomings of the current treatment options in acetabular revision surgery. Due to the severe bone deficiencies and poor bone quality, it can be very challenging to acquire adequate initial implant stability and long-term fixation. More advanced treatments, such as patient-specific implants, do guarantee the initial stability, but are formidably expensive and may eventually fail due to stress shielding. We, therefore, developed meta-implants furnished with a deformable porous outer layer. Upon implantation, this layer plastically deforms into the defects, thereby improving the initial stability and homogeneously stimulating the surrounding bone. We first studied the space-filling behavior of additively manufactured pure titanium lattices, based on six different unit cells, in a compression test complemented with full-field strain measurements. The diamond, body-centered cubic, and rhombic dodecahedron unit cells were eventually selected for the design of the deformable porous outer layer. Each design came in three different relative density profiles, namely maximum (MAX), functionally graded (FG), and minimum (MIN). After their compression in bone-mimicking molds with simulated acetabular defects, the space-filling behavior of the implants was evaluated using load-displacement curves, micro-CT images, and 3D reconstructions. The meta-implants with an FG diamond infill exhibited the most promising space-filling behavior. However, the required push-in forces exceed the impact forces currently applied in surgery. Future research should, therefore, focus on design optimization, to improve the space-filling behavior and to facilitate the implantation process for orthopedic surgeons. STATEMENT OF SIGNIFICANCE: Ideally, orthopedic implants would last for the entire lifetime of the patient. Unfortunately, they rarely do. Critically sized defects are a common sight in the revision of acetabular cups, and rather difficult to treat. The permanent deformation of lattice structures can be used to create shape-morphing implants that would fill up the defect site, and thereby restore the physiological loading conditions. Bending-dominated structures were incorporated in the porous outer layer of the space-filling meta-implants for their considerable lateral expansion in response to axial compression. A functionally graded density offered structural integrity at the joint while enhancing the deformability at the bone-implant interface. With the use of a more ductile metal, CP-Ti, these meta-implants could be deformed without strut failure.

The present crisis in male reproductive health: an urgent need for a political, social, and research roadmap.

BACKGROUND: There is a global crisis in male reproductive health. Evidence comes from globally declining sperm counts and increasing male reproductive system abnormalities, such as cryptorchidism, germ cell tumors, and onset of puberty. Male factor infertility occurs in ~40% of couples experiencing infertility. Data demonstrate an association between male infertility and overall health. Associated significant health conditions include diabetes mellitus, metabolic disorders, and cardiovascular disease. Adding to the complexity is that men typically do not seek health care unless there is acute medical need or, as in the case of the infertile couple, the male goes for a reproductive examination and semen analysis. However, 25% of the time a reproductive health examination does not occur. Couples are increasingly utilizing IVF at more advanced ages, and advanced paternal age is associated with increased risk for (i) adverse perinatal outcomes for both offspring and mother; (ii) early child mortality, cancer, and mental health issues. In addition to age, paternal lifestyle factors, such as obesity and smoking, impact not only the male fertility but also the offspring wellness. OBJECTIVES: The purpose of this paper was (i) to spotlight emerging and concerning data on male reproductive health, the relationship(s) between male reproductive and somatic health, and the heritable conditions father can pass to offspring, and (ii) to present a strategic roadmap with the goals of increasing (a) the awareness of men and society on the aforementioned, (b) the participation of men in healthcare seeking, and (c) advocacy to invigorate policy and funding agencies to support increased research into male reproductive biology. CONCLUSIONS: The Male Reproductive Health Initiative (MRHI) is a newly established and rapidly growing global consortium of key opinion leaders in research, medicine, funding and policy agencies, and patient support groups that are moving forward the significant task of accomplishing the goals of the strategic roadmap.

Evaluation of compressed sensing MRI for accelerated bowel motility imaging.

BACKGROUND: To investigate the feasibility of compressed sensing and parallel imaging (CS-PI)-accelerated bowel motility magnetic resonance imaging (MRI) and to compare its image quality and diagnostic quality to conventional sensitivity encoding (SENSE) accelerated scans. METHODS: Bowel MRI was performed in six volunteers using a three-dimensional balanced fast field-echo sequence. Static scans were performed after the administration of a spasmolytic agent to prevent bowel motion artefacts. Fully sampled reference scans and multiple prospectively 3× to 7× undersampled CS-PI and SENSE scans were acquired. Additionally, fully sampled CS-PI and SENSE scans were retrospectively undersampled and reconstructed. Dynamic scans were performed using 5× to 7× accelerated scans in the presence of bowel motion. Retrospectively, undersampled scans were compared to fully sampled scans using structural similarity indices. All reconstructions were visually assessed for image quality and diagnostic quality by two radiologists. RESULTS: For static imaging, the performance of CS-PI was lower than that of fully sampled and SENSE scans: the diagnostic quality was assessed as adequate or good for 100% of fully sampled scans, 95% of SENSE, but only for 55% of CS-PI scans. For dynamic imaging, CS-PI image quality was scored similar to SENSE at high acceleration. Diagnostic quality of all scans was scored as adequate or good; 55% of CS-PI and 83% of SENSE scans were scored as good. CONCLUSION: Compared to SENSE, current implementation of CS-PI performed less or equally good in terms of image quality and diagnostic quality. CS-PI did not show advantages over SENSE for three-dimensional bowel motility imaging.

Evaluation of gastrointestinal motility with MRI: Advances, challenges and opportunities.

Dynamic magnetic resonance imaging (MRI) of gastrointestinal motility has developed rapidly over the past few years. The non-invasive and non-ionizing character of MRI is an important advantage together with the fact that it is fast and can visualize the entire gastrointestinal tract. Advances in imaging and quantification techniques have facilitated assessment of gastric, small intestinal, and colonic motility in a clinical setting. Automated quantitative motility assessment using dynamic MRI meets the need for non-invasive techniques. Recently, studies have begun to examine this technique in patients, including those with IBD, pseudo-obstruction and functional bowel disorders. Remaining challenges for clinical implementation are processing the large amount of data, standardization and validation of the numerous MRI metrics and subsequently assessment of the potential role of dynamic MRI. This review examines the methods, advances, and remaining challenges of evaluation of gastrointestinal motility with MRI. It accompanies an article by Khalaf et al. in this journal that describes a new protocol for assessment of pan-intestinal motility in fasted and fed state in a single MRI session.

The cAMP-dependent kinase pathway and human sperm acrosomal exocytosis.

The human sperm acrosome reaction (AR) appears to be analogous to various somatic cell exocytotic events. The AR can be induced in vitro by naturally occurring and synthetic compounds, such as, human periovulatory follicular fluid (hFF) and calcium ionophore A23187. The events that culminate in the AR appear to involve at least two second messenger pathways. One pathway involves the generation of the second messenger adenosine 3':5'-cyclic monophosphate (cAMP) by the amplifying enzyme adenylate cyclase and leading to the activation of cAMP-dependent kinase (PKA). The effect of PKA stimulators, such as, forskolin and cAMP analogues, on AR was tested and they were found to stimulate the AR. Inhibitors of specific components in the PKA pathway, e.g. adenosine analogues and PKA inhibitors, induced dose-dependent reductions in the AR. Furthermore, naturally occurring agonists, including, hFF and solubilized human zona pellucida (sZP), in combination with PKA inhibitors, led to a significantly lower AR. Collectively, these data provide strong support for the role of the PKA pathway in the AR.

The zona pellucida-induced acrosome reaction of human spermatozoa is mediated by protein kinases.

OBJECTIVE: To determine if the solubilized human zona pellucida (ZP)-induced acrosome reaction is mediated by protein kinases. DESIGN: Capacitated spermatozoa were incubated with inhibitors of cyclic adenosine 3':5'-monophosphate (cAMP)-dependent kinase (KT5720), Ca(2+)- and phospholipid-dependent kinase (Calphostin C), and cyclic guanosine 3':5'-monophosphate (cGMP)-dependent kinase (KT5823) and then treated with a corresponding kinase stimulator (dibutyryl cAMP, phorbol 12-myristate 13-acetate and dibutyryl cGMP, respectively) to determine the effect on the acrosome reaction. Appropriate controls were performed. Zonae obtained from the unfertilized oocytes of women attending an IVF program were solubilized using acidic NaH2PO4, and the effect of solubilized ZP on the acrosome reaction was tested in dose-response fashion. Comparative studies with solubilized, zona-free oocyte-treated spermatozoa were performed. The effect of the kinase inhibitors on the solubilized ZP-induced acrosome reaction was then determined. RESULTS: No significant stimulation of the acrosome reaction by kinase stimulators occurred when spermatozoa were pretreated with inhibitors of the kinases, in contrast to the controls. Capacitated spermatozoa incubated with 2, 4, and 6 solubilized ZP showed a dose-dependent increase in the acrosome reaction. Solubilized oocytes had no effect on the acrosome reaction. Pretreatment of spermatozoa with kinase inhibitors significantly lowered the acrosome reaction induced by solubilized ZP but not completely. When a "cocktail" of the three inhibitors was used, a significant reduction in the acrosome reaction occurred in comparison with single inhibitor treatment. CONCLUSION: The present data indicate a role for human ZP-induced activation of multiple second messenger pathways, involving kinases A, C, and G in the human sperm acrosome reaction.

Induction of the human sperm acrosome reaction by human oocytes.

The acrosome reaction of human spermatozoa incubated in the presence or absence of vested human oocytes was investigated. All gametes were obtained from human in vitro fertilization (IVF) cases. Spermatozoa were collected after incubation in insemination medium only and following removal of the oocytes from insemination medium during the IVF procedure. After 16 hours of incubation 18.5% of the spermatozoa in insemination medium alone were acrosome-reacted compared to 31.5% for spermatozoa incubated in medium containing oocytes. The acrosome reaction of spermatozoa incubated with fertilized or unfertilized oocytes was also investigated. The percentage of acrosome reaction did not differ (P greater than 0.05) between the two groups (29.7% in the fertilized cases versus 30.7% in the unfertilized cases). Completion of oocyte nuclear maturation did not affect the proportion of acrosome-reacted spermatozoa observed with unfertilized eggs. A similar (P greater than 0.05) percentage of acrosome reacted spermatozoa were observed regardless of whether the unfertilized oocytes had (29%) or had not (35%) reached metaphase II. These findings indicate the acrosome reaction of human spermatozoa is enhanced in the presence of vested human oocytes. Furthermore, there is no apparent correlation between the percentage of the population of spermatozoa that acrosome react in the medium and the potential of an oocyte for fertilization.

Failure of multitube sperm swim-up for sex preselection.

OBJECTIVE: To use double-label fluorescence in situ hybridization to evaluate a modified swim-up procedure that is purported to be effective for preconceptual sex selection. DESIGN: Controlled, blinded study. SETTING: University hospital laboratories. PATIENT(S): Donor males reporting for routine semen analysis. MAIN OUTCOME MEASURE(S): Percentages of X- and Y-bearing spermatozoa in neat semen and in two swim-up fractions, determined using double-label fluorescence in situ hybridization. RESULT(S): No clinically significant change from a 1:1 ratio was found in the distribution of X- or Y-bearing spermatozoa after double-label fluorescence in situ hybridization following a modified swim-up procedure and irrespective of the time (15, 30, 45, and 60 minutes) allowed for swim-up. CONCLUSION(S): Using fluorescence in situ hybridization, a modified swim-up procedure was evaluated for its purported ability to skew the relative percentages of X- and Y-bearing spermatozoa. No clinically significant change in the ratio of X- to Y-bearing spermatozoa was detected independent of time. Therefore, clinical application of this procedure should be strongly discouraged.

Are capacitation or calcium ion influx required for the human sperm acrosome reaction?

OBJECTIVE: To determine if the acrosome reaction of human spermatozoa can occur without prior incubation to induce capacitation or in calcium-free medium. DESIGN: Noncapacitated (washed ejaculated) or capacitated (incubated for 3 hours in the presence of albumin) human spermatozoa were treated with either solubilized zonae pellucidae (ZP); a calcium ionophore (A23187); or activators of protein kinases A, G, and C, and the acrosomal status was monitored by the double stain technique. During agonist treatment, the capacitated spermatozoa were in medium either with or without calcium ions (Ca2+). The noncapacitated spermatozoa were always in Ca(2+)-containing medium. Sperm motility was monitored throughout the experiments. RESULTS: Solubilized ZP and kinase activators induced acrosomal exocytosis of capacitated spermatozoa (both in Ca(2+)-containing and Ca(2+)-free medium) and of noncapacitated spermatozoa. The lack of added Ca2+ or capacitation reduced the percentage of spermatozoa that reacted in response to solubilized ZP but not to the kinase activators. Ionophore A23187 stimulated acrosomal loss from noncapacitated spermatozoa to the same extent as capacitated spermatozoa in Ca(2+)-containing medium but had no effect on capacitated spermatozoa in Ca(2+)-free medium. CONCLUSIONS: Human spermatozoa do not require incubation under capacitating conditions or the presence of extracellular Ca2+ before they can undergo the acrosome reaction in response to certain agonists. Therefore, Ca2+ influx and/or preincubation to induce capacitation are not absolute requirements for the in vitro agonist-induced acrosome reaction. However, these conditions can optimize the acrosome reaction response to zona proteins. The intracellular mechanisms leading to the acrosome reaction appear to be functional in noncapacitated spermatozoa but membrane changes probably are required before certain extracellular ligands such as zona proteins can exert their maximal effect.

Inhibition of the human sperm acrosome reaction by a high molecular weight factor from human seminal plasma.

Human seminal plasma possesses a factor (acrosome reaction-inhibitory factor) that is precipitated by high speed centrifugation and that inhibits the ionophore- and dbc AMP-induced acrosome reaction of capacitated human spermatozoa but only if it is added toward the end of the capacitation period. Acrosome reaction-inhibitory factor can be partially purified by cation exchange chromatography and appears to differ from another factor that can be obtained by ultracentrifugation of human seminal plasma and that prevents the fertilization of mouse gametes.

Evidence for a role of cysteinyl leukotrienes in mouse and human sperm function.

The in vitro fertilizing capacity of mouse spermatozoa was inhibited by FPL-55712, a receptor antagonist of the cysteinyl-containing leukotrienes LTC4, LTD4, and LTE4. Inhibition occurred whether the compound was present in the medium during the capacitation period or during the fertilization period. Additionally, FPL-55712 inhibited the penetration of human spermatozoa into zona-free hamster oocytes. Inhibition of fertilization did not appear to be caused by an effect on sperm motility or on the oocyte. These observations suggest that mouse and human spermatozoa require cysteinyl leukotriene activity for both fertilization and oocyte penetration.