Atualizações científicas – 16 a 20 de janeiro de 2012

Publicado em: 23 de Janeiro de 2012

Conheça mais sobre Reprodução Humana com as publicações científicas da última semana.

What’s NOT to eat-food adulteration in the context of human biology

Publicado em 19 de Janeiro de 12 pelo American Journal of Human Biology, disponível no Oxfor Journal.

Resumo:

Food has nutritional and non-nutritional components. The latter are not well-studied despite the fact that food adulteration has been common. Food adulteration may have reached its peak in cities of Western Europe and the US in the 18th and 19th centuries when foods were often purposely contaminated with additives to increase bulk, attractiveness, disguise spoilage, and increase profit. Effective regulation of food began in the late 19th and 20th centuries. Nevertheless, today food recalls for bacterial contamination are common, while pesticides and compounds from manufacturing are detected in many foods. Foods with strong reputations for healthiness, such as salmon, may have sizable contaminant contents. The contaminant content of many foods varies by origin and season. Nearly all commercially raised salmon has higher contaminant levels than wild caught salmon. Opting out of the commercial food distribution system is an option, but the value depends on the habitat in which the food is obtained. Traditionally, the Akwesasne Mohawk Nation has depended on local fish and wildlife for their diet. Now pollution of local waterways has led to the contamination of many local foods, and levels of the contaminant polychlorinated biphenyls in the Akwesasne Mohawk people reflect current or past dietary patterns. Many other communities in nonurban settings are exposed to contaminants through long-trail distribution of contaminants in food, air, and/or water. Human biologists considering nutrition, disease, growth, reproduction, aging, to name a few areas, may consider the non-nutritional components of food as many have the ability to alter physiological functioning.

HIV transmissions by stage in dynamic sexual partnerships

Publicado em 12 de Janeiro de 12 pelo Journal of Theoretical Biology, disponível no Pub Med.

Resumo:

Most models assessing relative transmissions during different progressive stages of human immunodeficiency virus (HIV) infection assume that infections are transmitted through instantaneous sexual contacts. In reality, however, HIV will often be transmitted through repeated sex acts during partnerships that form and dissolve at varying rates. We sought to understand how dynamic sexual partnerships would influence transmissions during different progression stages of HIV infection: primary HIV infection (PHI) and chronic stage. Using a system of ordinary differential equations with a pair approximation technique, we constructed a model of HIV transmission in a homogeneous population in which sexual partnerships form and dissolve. We derived analytical expressions for useful epidemiological quantities such as basic reproduction number and also did imulation runs of the model. Partnership dynamics strongly influence transmissions during progressive stages of HIV infection. The fraction of transmissions during PHI has a U-shaped relationship with respect to the rate of partnership change, where the minimum and maximum occur given partnerships of about 100 days and fixed partnerships, respectively. Models that assume instantaneous contacts may overestimate transmissions during PHI for real, dynamic sexual partnerships with varying (non-zero) durations.

Perspectives of canadian oocyte donors and recipients on donor compensation and the establishment of a personal health information registry

Publicado em Janeiro de 12 pelo Journal of Obstetrics and Gynaecology Canada, disponível no Pub Med.

Resumo:

We report the views of 33 women who were involved in an altruistic oocyte donation program about provisions under Canada’s Assisted Human Reproduction Act 2004 to prohibit donor compensation and to establish a Personal Health Information Registry. The participants had been either donors of oocytes to a recipient known to them (15) or recipients of such donation (18) through services provided by a clinic in a large Canadian city, and they each participated in a semi-structured face-to-face or telephone interview. Among the 15 donor participants, seven were friends of the recipient, six were sisters, one was a niece of the recipient, and one donor donated twice, once to her sister and once to a friend. In eight cases the donor and recipient participated in interviews independently. At the time of interview, 11 of the 25 separate cases had resulted in a live birth and one in an ongoing pregnancy, so that “successful” and “unsuccessful” donations were equally represented among participants. While divergent views were reported among and between donors and recipients on an altruistic model versus a compensated model of donation, most participants largely endorsed the establishment of a personal health information registry.

Solely inhibin B producing ovarian tumour as a cause of secondary amenorrhoea with hot flushes: case report and review of literature

Publicado em Dezembro de 11 pela Human Reproduction, disponível no Pub Med.

Resumo:

In this report, we describe a case of a solely inhibin B producing fibrothecoma presenting with secondary amenorrhoea and hot flushes. Typical laboratory findings were an elevated LH, elevated inhibin B, low FSH and low estrogen. The World Health Organization classification of amenorrhoea was not applicable since the combination of low estrogen and low FSH suggested a central cause, whereas actually there was an ovarian cause. With staging laparotomy, a bilateral borderline tumour was detected in combination with a fibrothecoma. This report underpins the concept of inhibin B being a selective FSH secretion inhibitor of ovarian origin. Furthermore, a literature review on these topics is included.

Vitrification at the pre-antral stage transiently alters inner mitochondrial membrane potential but proteome of in vitro grown and matured mouse oocytes appears unaffected

Publicado em 11 de Janeiro de 12 pela Human Reproduction, disponível no Pub Med.

Resumo:

Vitrification is a fast and effective method to cryopreserve ovarian tissue, but it might influence mitochondrial activity and affect gene expression to cause persistent alterations in the proteome of oocytes that grow and mature following cryopreservation.METHODSIn part one of the study, the inner mitochondrial membrane potential (Ψ(mit)) of JC-1 stained oocytes from control and CryoTop vitrified pre-antral follicles was analyzed by confocal microscopy at Day 0, or after culture of follicles for 1 or 12 days. In part two, proteins of in vivo grown germinal vesicle (GV) oocytes were subjected to proteome analysis by SDS polyacrylamide gel electrophoresis, tryptic in-gel digestion of gel slices, and one-dimensional-nano-liquid chromatography of peptides on a multi-dimensional-nano-liquid chromatography system followed by mass spectrometry (LC-MS/MS) and Uniprot Gene Ontology (GO) analysis. In part three, samples containing the protein amount of 40 GV and metaphase II (MII) oocytes, respectively, from control and vitrified pre-antral follicles cultured for 12 or 13 days were subjected to 2D DIGE saturation labeling and separated by isoelectric focusing and SDS gel electrophoresis (2D DIGE), followed by DeCyder(Tm) analysis of spot patterns in three independent biological replicates. Statistical and hierarchical cluster analysis was employed to compare control and vitrified groups.

RESULTS(i) Mitochondrial inner membrane potential differs significantly between control and vitrified GV oocytes at Day 0 and Day 1, but is similar at Day 12 of culture. (ii) LC-MS/MS analysis of SDS gel fractionated protein lysates of 988 mouse GV oocytes revealed identification of 1123 different proteins with a false discovery rate of <1%. GO analysis assigned 811 proteins to the ‘biological process’ subset. Thirty-five percent of the proteins corresponded to metabolic processes, about 15% to mitochondrion and transport, each, and close to 8% to oxidation-reduction processes. (iii) From the 2D-saturation DIGE analysis 1891 matched spots for GV-stage and 1718 for MII oocyte proteins were detected and the related protein abundances in vitrified and control oocytes were quantified. None of the spots was significantly altered in intensity, and hierarchical cluster analysis as well as histograms of p and q values suggest that vitrification at the pre-antral stage does not significantly alter the proteome of GV or MII oocytes compared with controls.

CONCLUSIONSVitrification appears to be associated with a significant transient increase in Ψ(mit) in oocyte mitochondria, which disappears when oocyte/cumulus cell apposition is restored upon development to the antral stage. The nano-LC-MS/MS analysis of low numbers of oocytes is useful to obtain information on relevant biological signaling pathways based on protein identifications. For quantitative comparisons, saturation 2D DIGE analysis is superior to LC-MS/MS due to its high sensitivity in cases where the biological material is very limited. Genetic background, age of the female, and/or stimulation protocol appear to influence the proteome pattern. However, the quantitative 2D DIGE approach provides evidence that vitrification does not affect the oocyte proteome after recovery from transient loss of cell-cell interactions, in vitro growth and in vitro maturation under tested conditions. Therefore, transient changes in mitochondrial activity by vitrification do not appear causal to persistent alterations in the mitochondrial or overall oocyte proteome.

The effect of postponement of first motherhood on permanent involuntary childlessness and total fertility rate in six European countries since the 1970s

Publicado em 18 de Janeiro de 12 pela Human Reproduction, disponível no Pub Med.

Resumo:

Postponement of childbearing since the 1970s has led to an increase in permanent involuntarily childlessness. We will address the magnitude of this trend, the effect of IVF/ICSI and the effect on total fertility rate (TFR an often used demographic measure for the level of fertility) in six EU countries.

METHODS: Using a fertility micro-simulation model, we estimate the effect of postponement of first motherhood on permanent involuntary childlessness in six representative European countries since 1970/1985: Sweden, Austria, Czech Republic, The Netherlands, West Germany and Spain. To estimate the effect of IVF/ICSI on this trend, we use data on the results of all IVF/ICSI cycles performed in The Netherlands in 2003 and 2004.RESULTSPermanent involuntary childlessness approximately doubled since 1970s and rose to ∼4% in the Czech Republic and to ∼7% in Spain with the other countries in between. If all couples entitled to have IVF/ICSI were to be treated, the effect of postponement would almost have been neutralized. However, only a limited proportion of eligible couple are being treated. Without postponement, TFRs would have been between 0.03 and 0.05 higher.

CONCLUSIONS: The effect of postponement on permanent involuntary childlessness is considerable. So far IVF/ICSI only had a slight effect on this trend. The impact of postponement on TFRs is small compared with other demographic trends.

Tackling burden in ART: an integrated approach for medical staff

Publicado em 18 de Janeiro de 12 pela Human Reproduction, disponível no Pub Med.

Resumo:

Discontinuation is a problem in fertility clinics. Many couples discontinue assisted reproductive technologies (ART) without achieving a live birth for reasons other than poor prognosis or the cost of treatment. Discontinuation has been attributed to the burden of treatment. The causes of burden can be broadly classified according to whether they originate in the patient, clinic or treatment. Interventions to alleviate these burdens include provision of comprehensive educational material, screening to identify highly distressed patients, provision of tailored coping tools and improvements in the clinic environment and medical interventions. Practical interventions to reduce the different causes of burden in ART exist, but further development and evaluation of the efficacy of these interventions requires more precise definition of terms and theory. In this paper, we propose a general integrated approach to cover different perspectives in dealing with burden in ART clinics. We firstly describe the integrated approach and present common sources of burden. We then describe interventions that could help reduce the burden in ART. Our paper is aimed at fertility clinic staff because of their day-to-day involvement with patients. However, this discussion should also be relevant to companies that develop treatments and to psychosocial experts. Reducing the burden of treatment should lead to improved outcomes, namely better quality of life during treatment and lower discontinuation rates.

Assisted reproduction using donated embryos: outcomes from surveillance systems in six countries

Publicado em 17 de Janeiro de 12 pela Human Reproduction, disponível no Pub Med.

Resumo:

Embryo donation, though less often performed than other assisted reproductive technology (ART), can represent an attractive option for couples who do not wish to discard their embryos remaining after IVF, and for those who cannot or should not conceive naturally. Clinicians and potential participants could benefit from information comparing outcomes of embryo donation with those of other ARTs, in various countries.

METHODS: We analyzed outcome information from ART treatment cycles using 2001-2008 data from national surveillance systems in the USA, Canada, the UK, Australia, New Zealand and Finland. We calculated the live birth rate (LBR) with relative risks, the average number of embryos transferred per cycle and the ratio between them (LBR per embryo transferred). We compared outcomes of embryo donation cycles with those for autologous IVF, frozen embryo transfer (FET) and oocyte donation (OD).

RESULTS: LBRs for embryo donation cycles were 14-33%, compared with 16-28% for autologous FET, 22-35% for autologous IVF and 15-52% for OD. In every country except Australia/New Zealand, and in all countries combined, the LBR for embryo donation approximated that for IVF, with no statistically significant differences in Finland and Canada. The average number of embryos transferred per cycle was 1.5-2.8. The LBR per embryo transferred was 11-12% for donor embryo cycles, compared with 8-11% for autologous FET, 12-15% for autologous IVF and 9-21% for OD.

CONCLUSIONS: We found that transfer of donated embryos in these countries yields pregnancy outcomes comparable to those of autologous ART procedures. The variation in outcome rates among countries is not entirely explained by the number of embryos transferred. The relatively high success rates and low costs make embryo donation an attractive family building alternative.

Anti-Mullerian hormone as a predictor of follicular reserve in ovarian insufficiency: special emphasis on FSH-resistant ovaries

Publicado em 17 de Janeiro de 12 pela Human Reproduction, disponível no Pub Med.

Resumo:

Anti-Müllerian hormone (AMH) is secreted by ovarian granulosa cells and its serum levels reflect ovarian follicle reserve. The main objective of this study was to test the use of AMH assay in identifying women with primary amenorrhea (PA) and existing follicles and to study follicle phase dependent AMH secretion.

METHODS: Serum levels of AMH were measured in subjects with FSH-resistant ovaries (FSHRO, n= 12), primary ovarian insufficiency (POI) with PA (n= 11) or secondary amenorrhea (SA n= 20) of unknown etiology, and controls (n= 23), and in Turner syndrome (TS) [45,X (n= 18), mosaicism (n= 7), structural X chromosome abnormalities (SCA, n= 10)], and healthy controls (n= 34).RESULTSSerum levels of AMH in women with FSHRO were comparable with those in control women (2.76 ± 2.37  versus 3.77 ± 2.36 ng/ml) and significantly higher than in women with PA (0.05 ± 0.04 ng/ml; P < 0.001) or SA of unknown origin (0.12 ± 0.20 ng/ml; P < 0.001). TS girls/women with 45,X or SCA had low serum AMH levels (0.13 ± 0.09 and 0.27 ± 0.19 ng/ml) compared with their controls (3.34 ± 2.23 ng/ml) or subjects with mosaicism (2.33 ± 2.81 ng/ml). AMH expression was detected in granulosa cells of women with FSHRO but not in any of the 45,X fetal ovarian specimens.

CONCLUSIONS: A serum AMH assay could be used to identify patients with decreasing ovarian reserves and POI. Moreover, our results support the notion that AMH is secreted mainly by small non-selected follicles, since follicular granulosa cells were AMH-positive and serum AMH levels were normal/low normal in women with FSHRO, who lack follicle development beyond the small antral stage.

Estimating the prevalence of infertility in Canada

Publicado em 17 de Janeiro de 12 pela Human Reproduction, disponível no Pub Med.

Resumo:

Over the past 10 years, there has been a significant increase in the use of assisted reproductive technologies in Canada, however, little is known about the overall prevalence of infertility in the population. The purpose of the present study was to estimate the prevalence of current infertility in Canada according to three definitions of the risk of conception.

METHODS: Data from the infertility component of the 2009-2010 Canadian Community Health Survey were analyzed for married and common-law couples with a female partner aged 18-44. The three definitions of the risk of conception were derived sequentially starting with birth control use in the previous 12 months, adding reported sexual intercourse in the previous 12 months, then pregnancy intent. Prevalence and odds ratios of current infertility were estimated by selected characteristics.

RESULTS: Estimates of the prevalence of current infertility ranged from 11.5% (95% CI 10.2, 12.9) to 15.7% (95% CI 14.2, 17.4). Each estimate represented an increase in current infertility prevalence in Canada when compared with previous national estimates. Couples with lower parity (0 or 1 child) had significantly higher odds of experiencing current infertility when the female partner was aged 35-44 years versus 18-34 years. Lower odds of experiencing current infertility were observed for multiparous couples regardless of age group of the female partner, when compared with nulliparous couples.

CONCLUSIONS: The present study suggests that the prevalence of current infertility has increased since the last time it was measured in Canada, and is associated with the age of the female partner and parity.

Conteúdo atualizado em: 17 de Abril de 2014

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