Purewal S.,Middlesex University |
van den Akker O.,Middlesex University |
van den Akker O.,Center for Human Reproductive Science
Fertility and Sterility | Year: 2010
Objective: In 2007, the Human Fertilization and Embryology Authority permitted oocyte donation for research through voluntary donation or within an oocyte share model. The aims of this study were to investigate volunteer (nonpatient) women's attitudes and intentions to donate using components of the Theory of Planned Behavior and their attitudes toward parenthood through structural equation modeling. Design: Questionnaires. Setting: Online. Patient(s): A total of 253 nonpatient women. Main Outcome Measure(s): Attitudes towards oocyte donation for research and reasons for parenthood scale. Result(s): Of the 253 respondents, 94 were potential donors, 98 were possible donors, and 61 were non-donors. Most potential donors (68%) reported no preference towards donating their oocytes for research or an infertile couple. Structural equation modeling revealed that age (β = -.03) and components of the TPB (β = .16) had a statistically significant direct effect on intentions to donate for research. Attitudes toward parenthood was not linked to intentions to donate for research. Conclusion(s): There appears to be a strong altruistic motive along with the theoretical underpinnings of positive attitudes, feeling supported, and accepting the consequences of oocyte donation for research, suggesting these have the potential to inform recruitment practices and tailor clinical services. © 2010 American Society for Reproductive Medicine.
Robinson L.,Center for Human Reproductive Science |
Gallos I.D.,Center for Human Reproductive Science |
Gallos I.D.,University of Birmingham |
Conner S.J.,Center for Human Reproductive Science |
And 8 more authors.
Human Reproduction | Year: 2012
STUDY QUESTIONIs there an association between high levels of sperm DNA damage and miscarriage? SUMMARY ANSWERMiscarriage rates are positively correlated with sperm DNA damage levels. WHAT IS KNOWN ALREADYMost ejaculates contain a subpopulation of sperm with DNA damage, also referred to as DNA fragmentation, in the form of double or single-strand breaks which have been induced in the DNA prior to or following ejaculation. This DNA damage may be particularly elevated in some subfertile men, hence several studies have examined the link between sperm DNA damage levels and conception and miscarriage rates. STUDY DESIGN, SIZE, DURATIONA systematic review and meta-analysis of studies which examined the effect of sperm DNA damage on miscarriage rates was performed. Searches were conducted on MEDLINE, EMBASE and the Cochrane Library without any language restrictions from database inception to January 2012. PARTICIPANTS/MATERIALS, SETTING, METHODSWe used the terms 'DNA damage' or 'DNA fragmentation' combined with 'miscarriage', 'abortion' or 'pregnancy' to generate a set of relevant citations. Data extraction was performed by two reviewers. Study quality was assessed using the NewcastleOttawa Scale. Meta-analysis of relative risks of miscarriage was performed with a random effects model. Subgroup analyses were performed by the type of DNA damage test, whether the sperm examined were prepared or from raw semen and for pregnancies resulting from IVF or ICSI treatment. MAIN RESULTS AND THE ROLE OF CHANCEWe identified 16 cohort studies (2969 couples), 14 of which were prospective. Eight studies used acridine orange-based assays, six the TUNEL assay and two the COMET assay. Meta-analysis showed a significant increase in miscarriage in patients with high DNA damage compared with those with low DNA damage [risk ratio (RR) 2.16 (1.54, 3.03), P < 0.00001)]. A subgroup analysis showed that the miscarriage association is strongest for the TUNEL assay (RR 3.94 (2.45, 6.32), P < 0.00001). LIMITATIONS, REASONS FOR CAUTIONThere is some variation in study characteristics, including the use of different assays and different thresholds for DNA damage and the definition of pregnancy loss. WIDER IMPLICATIONS OF THE FINDINGSThe use of methods which select sperm without DNA damage for use in assisted conception treatment may reduce the risk of miscarriage. This finding indicates that assays detecting DNA damage could be considered in those suffering from recurrent pregnancy loss. Further research is necessary to study the mechanisms of DNA damage and the potential therapeutic effects of antioxidant therapy. STUDY FUNDING/COMPETING INTEREST(S)None. © 2012 The Author.
Montenegro-Johnson T.D.,University of Birmingham |
Montenegro-Johnson T.D.,Center for Human Reproductive Science |
Smith D.J.,University of Birmingham |
Smith D.J.,Center for Human Reproductive Science |
And 2 more authors.
Physics of Fluids | Year: 2013
Shear-thinning is an important rheological property of many biological fluids, such as mucus, whereby the apparent viscosity of the fluid decreases with shear. Certain microscopic swimmers have been shown to progress more rapidly through shear-thinning fluids, but is this behavior generic to all microscopic swimmers, and what are the physics through which shear-thinning rheology affects a swimmer's propulsion? We examine swimmers employing prescribed stroke kinematics in two-dimensional, inertialess Carreau fluid: shear-thinning "generalized Stokes" flow. Swimmers are modeled, using the method of femlets, by a set of immersed, regularized forces. The equations governing the fluid dynamics are then discretized over a body-fitted mesh and solved with the finite element method. We analyze the locomotion of three distinct classes of microswimmer: (1) conceptual swimmers comprising sliding spheres employing both one- and two-dimensional strokes, (2) slip-velocity envelope models of ciliates commonly referred to as "squirmers," and (3) monoflagellate pushers, such as sperm. We find that morphologically identical swimmers with different strokes may swim either faster or slower in shear-thinning fluids than in Newtonian fluids. We explain this kinematic sensitivity by considering differences in the viscosity of the fluid surrounding propulsive and payload elements of the swimmer, and using this insight suggest two reciprocal sliding sphere swimmers which violate Purcell's Scallop theorem in shear-thinning fluids. We also show that an increased flow decay rate arising from shear-thinning rheology is associated with a reduction in the swimming speed of slip-velocity squirmers. For sperm-like swimmers, a gradient of thick to thin fluid along the flagellum alters the force it exerts upon the fluid, flattening trajectories and increasing instantaneous swimming speed. © Author(s) 2013.
Van Den Akker O.B.A.,Middlesex University |
Van Den Akker O.B.A.,Center for Human Reproductive Science |
Purewal S.,Middlesex University
Reproductive BioMedicine Online | Year: 2011
This study tested the effectiveness of the framing effect and fear appeals to inform young people about the risks of multiple births and the option of selecting elective single-embryo transfer (eSET). A non-patient student sample (age (mean ± SD) 23 ± 5.5 years; n = 321) were randomly allocated to one of seven groups: (1) framing effect: (1a) gain and (1b) loss frame; (2) fear appeal: (2a) high, (2b) medium and (2c) low fear; or (3) a control group: (3a) education and (3b) non-education. The primary outcome measure was the Attitudes towards Single Embryo Transfer questionnaire, before exposure to the messages (time 1) and immediately afterwards (time 2). Results revealed participants in the high fear, medium fear and gain condition demonstrated the most positive and significant differences (P < 0.001 to P < 0.05) in their knowledge, hypothetical intentions and modest changes in attitudes towards eSET than the low fear, loss frame and education and non-education messages. The results demonstrate that the use of complex persuasive communication techniques on a student population to promote immediate and hypothetical eSET preferences is more successful at promoting eSET than merely reporting educational content. Future research should investigate its application in a clinical population. A multiple pregnancy is a health risk to both infant and mother following IVF treatment. The aims of this study were to test the effectiveness of two persuasive communication techniques (the framing effect and fear appeals) to inform young people about the risks of multiple births and the hypothetical option of selecting elective single-embryo transfer (eSET) (i.e., only one embryo is transferred to the uterus using IVF treatment). A total of 321 non-patient student sample (mean age 23) were randomly allocated to read a message from one of seven groups: (1) framing effect: (1a) gain and (1b) loss frame; (2) fear appeal: (2a) high, (2b) medium and (2c) low fear; or (3) a control group: education (3a) and (3b) non-education. Participants completed the Attitudes towards Single Embryo Transfer questionnaire, before exposure to the messages (time 1) and immediately afterwards (time 2). Results revealed that participants in the high fear, medium fear and gain condition demonstrated the most positive and significant differences in their knowledge, hypothetical intentions and modest changes in attitudes towards eSET than the low fear, loss frame and education and non-education messages. This study recommends that health promotion based on the framing effect and fear appeals should be tested in clinical (patient) samples in the future. © 2011, Taiwanese Dermatological Association. Published by Elsevier Taiwan LLC. All rights reserved.
Gaffney E.A.,University of Oxford |
Gaffney E.A.,Center for Human Reproductive Science |
Gadelha H.,University of Oxford |
Gadelha H.,Center for Human Reproductive Science |
And 7 more authors.
Annual Review of Fluid Mechanics | Year: 2011
Mammalian spermatozoa motility is a subject of growing importance because of rising human infertility and the possibility of improving animal breeding. We highlight opportunities for fluid and continuum dynamics to provide novel insights concerning the mechanics of these specialized cells, especially during their remarkable journey to the egg. The biological structure of the motile sperm appendage, the flagellum, is described and placed in the context of the mechanics underlying the migration of mammalian sperm through the numerous environments of the female reproductive tract. This process demands certain specific changes to flagellar movement and motility for which further mechanical insight would be valuable, although this requires improved modeling capabilities, particularly to increase our understanding of sperm progression in vivo. We summarize current theoretical studies, highlighting the synergistic combination of imaging and theory in exploring sperm motility, and discuss the challenges for future observational and theoretical studies in understanding the underlying mechanics. © 2011 by Annual Reviews. All rights reserved.