STUDY QUESTION

What are the effects of continuous sauna exposure on seminal parameters, sperm chromatin, sperm apoptosis and expression of genes involved in heat stress and hypoxia?

SUMMARY ANSWER

Scrotal hyperthermia by exposure to sauna can induce a significant alteration of spermatogenesis.

WHAT IS KNOWN ALREADY

Several authors have evidenced that high temperature has dramatic effects on spermatogenesis.

STUDY DESIGN, SIZE AND DURATION

A longitudinal time-course study. Data from 10 subjects exposed to Finnish sauna were collected before sauna (T0), after3 months of sauna sessions (T1) and after 3 (T2) and 6 months (T3) from the end of sauna exposure.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Ten normozoospermic volunteers underwent two sauna sessions per week for 3 months, at 80–90°C, each lasting 15 min. Sex hormones, sperm parameters, sperm chromatin structure, sperm apoptosis and expression of genes involved in heat stress and hypoxia were evaluated at the start, at the end of sauna exposure and after 3 and 6 months from sauna discontinuation. Student's t-test for paired data was used for statistical analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

At the end of sauna exposure, we found a strong impairment of sperm count and motility (P < 0.001), while no significant change in sex hormones was present. Decreases in the percentage of sperm with normal histone-protamine substitution (78.7 ± 4.5 versus 69.0 ± 4.1), chromatin condensation (70.7 ± 4.7 versus 63.6 ± 3.3) and mitochondrial function (76.8 ± 4.9 versus 54.0 ± 6.1) were also evident at T1, and strong parallel up-regulation of genes involved in response to heat stress and hypoxia was found. All these effects were completely reversed at T3.

LIMITATIONS AND REASONS FOR CAUTION

Absence of subjects with abnormal sperm parameters was the major limitation of this study.

WIDER IMPLICATIONS OF THE FINDINGS

Our data demonstrated for the first time that in normozoospermic subjects, sauna exposure induces a significant but reversible impairment of spermatogenesis, including alteration of sperm parameters, mitochondrial function and sperm DNA packaging. The large use of Finnish sauna in Nordic countries and its growing use in other parts of the world make it important to consider the impact of this lifestyle choice on men's fertility.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was sought for this study and the authors have no conflict of interest to declare.

Source:
http://humrep.oxfordjournals.org/cgi/content/short/28/4/877?rss=1

Recommendation and review posted by G. Smith

STUDY QUESTION

Is perinatal germ cell (GC) differentiation in the marmoset similar to that in the human?

SUMMARY ANSWER

In a process comparable with the human, marmoset GC differentiate rapidly after birth, losing OCT4 expression after 5–7 weeks of age during mini-puberty.

WHAT IS KNOWN ALREADY

Most of our understanding about perinatal GC development derives from rodents, in which all gonocytes (undifferentiated GC) co-ordinately lose expression of the pluripotency factor OCT4 and stop proliferating in late gestation. Then after birth these differentiated GC migrate to the basal lamina and resume proliferation prior to the onset of spermatogenesis. In humans, fetal GC differentiation occurs gradually and asynchronously and OCT4⁺ GC persist into perinatal life. Failure to switch off OCT4 in GC perinatally can lead to development of carcinoma in situ (CIS), the precursor of testicular germ cell cancer (TGCC), for which there is no animal model. Marmosets show similarities to the human, but systematic evaluation of perinatal GC development in this species is lacking. Similarity, especially for loss of OCT4 expression, would support use of the marmoset as a model for the human and for studying CIS origins.

STUDY DESIGN, SIZE AND DURATION

Testis tissues were obtained from marmosets (n = 4–10 per age) at 12–17 weeks' gestation and post-natal weeks 0.5, 2.5, 5–7, 14 and 22 weeks, humans at 15–18 weeks' gestation (n = 5) and 4–5 weeks of age (n = 4) and rats at embryonic day 21.5 (e21.5) (n = 3) and post-natal days 4, 6 and 8 (n = 4 each).

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Testis sections from fetal and post-natal marmosets, humans and rats were collected and immunostained for OCT4 and VASA to identify undifferentiated and differentiated GC, respectively, and for Ki67, to identify proliferating GC. Stereological quantification of GC numbers, differentiation (% OCT4⁺ GC) and proliferation were performed in perinatal marmosets and humans. Quantification of GC position within seminiferous cords was performed in marmosets, humans and rats.

MAIN RESULTS AND ROLE OF CHANCE

The total GC number increased 17-fold from birth to 22 post-natal weeks in marmosets; OCT4⁺ and VASA⁺ GC proliferated equally in late gestation and early post-natal life. The percentage of OCT4⁺ GC fell from 54% in late fetal life to <0.5% at 2.5 weeks of age and none were detected after 5–7 weeks in marmosets. In humans, the percentage of OCT4⁺ GC also declined markedly during the equivalent period. In marmosets, GC had begun migrating to the base of seminiferous cords at ~22 weeks of age, after the loss of GC OCT4 expression.

LIMITATIONS, REASONS FOR CAUTION

There is considerable individual variation between marmosets. Although GC development in marmosets and humans was similar, there are differences with respect to proliferation during fetal life. The number of human samples was limited.

WIDER IMPLICATIONS OF THE FINDINGS

The similarities in testicular GC differentiation between marmosets and humans during the perinatal period, and their differences from rodents, suggest that the marmoset may be a useful model for studying the origins of CIS, with relevance for the study of TGCC.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by Grant G33253 from the Medical Research Council, UK. No external funding was sought and there are no competing interests.

Source:
http://humrep.oxfordjournals.org/cgi/content/short/28/4/886?rss=1

Recommendation and review posted by G. Smith

STUDY QUESTION

What issues remain to be solved before fertility preservation and transplantation can be offered to prepubertal boys?

SUMMARY ANSWER

The main issues that need further investigation are malignant cell decontamination, improvement of in vivo fertility restoration and in vitro maturation.

WHAT IS KNOWN ALREADY

Prepubertal boys who need gonadotoxic treatment might render sterile for the rest of their life. As these boys do not yet produce sperm cells, they cannot benefit from sperm banking. Spermatogonial stem cell (SSC) banking followed by autologous transplantation has been proposed as a fertility preservation strategy. But before this technique can be applied in the clinic, some important issues have to be resolved.

STUDY DESIGN, SIZE DURATION

Original articles as well as review articles published in English were included in a search of the literature.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Relevant studies were selected by an extensive Medline search. Search terms were fertility preservation, cryopreservation, prepubertal, SSC, testis tissue, transplantation, grafting and in vitro spermatogenesis. The final number of studies selected for this review was 102.

MAIN RESULTS AND THE ROLE OF CHANCE

Cryopreservation protocols for testicular tissue have been developed and are already being used in the clinic. Since the efficiency and safety of SSC transplantation have been reported in mice, transplantation methods are now being adapted to the human testes. Very recently, a few publications reported on in vitro spermatogenesis in mice, but this technique is still far from being applied in a clinical setting.

LIMITATIONS, REASONS FOR CAUTION

Using tissue from cancer patients holds a potential risk for contamination of the collected testicular tissue. Therefore, it is of immense importance to separate malignant cells from the cell suspension before transplantation. Because biopsies obtained from young boys are small and contain only few SSCs, propagation of these cells in vitro will be necessary.

WIDER IMPLICATIONS OF THE FINDINGS

The ultimate use of the banked tissue will depend on the patient's disease. If the patient was suffering from a non-malignant disease, tissue grafting might be offered. In cancer patients, decontaminated cell suspensions will be injected in the testis. For patients with Klinefelter syndrome, the only option would be in vitro spermatogenesis. However, at present, restoring fertility in cancer and Klinefelter patients is not yet possible.

STUDY FUNDING/COMPETING INTEREST(S)

Research Foundation, Flanders (G.0385.08 to H.T.), the Institute for the Agency for Innovation, Belgium (IWT/SB/111245 to E.G.), the Flemish League against Cancer (to E.G.), Kom op tegen kanker (G.0547.11 to H.T.) and the Fund Willy Gepts (to HT). E.G. is a Postdoctoral Fellow of the FWO, Research Foundation, Flanders. There are no conflicts of interest.

Source:
http://humrep.oxfordjournals.org/cgi/content/short/28/4/897?rss=1

Recommendation and review posted by G. Smith

STUDY QUESTION

Are women with asthma, and more specifically those with severe or uncontrolled asthma, at higher risk of spontaneous and induced abortions?

SUMMARY ANSWER

Pregnant women with asthma, notably when uncontrolled, are at higher risk of spontaneous abortion.

WHAT IS KNOWN ALREADY

Only one study has examined the association between asthma and spontaneous and induced abortions and revealed a modest increase in the risk of spontaneous abortions, particularly in women with more severe asthma and those with previous exacerbations, and a marginal decrease in the risk of induced abortions.

STUDY DESIGN, SIZE, DURATION

A cohort of pregnancies from asthmatic (n = 15 107) and non-asthmatic (n = 34 331) women was reconstructed by linking three administrative databases from Quebec (Canada), between 1992 and 2002. The cohort included 7870 spontaneous abortions, 14 596 induced abortions and 26 972 live births.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pregnant women with and without asthma were analyzed. Asthma was defined by at least one asthma diagnosis and one dispensed prescription for an asthma medication in the 2 years prior to or during pregnancy. Asthma severity and control were assessed using validated indexes in the year before the 20th week of pregnancy or the termination of the pregnancy. Logistic polytomous regression models were used to estimate the relationship between asthma and asthma severity and control on the risk of abortion, while adjusting for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

The prevalence of spontaneous and induced abortions was 15.9 and 29.5%, respectively. Maternal asthma was associated with an increased risk of a spontaneous abortion [odds ratio (OR) = 1.41; 95% confidence interval (CI): 1.33–1.49] and a decreased risk of induced abortions (OR = 0.92; 0.88–0.97). No association was observed between asthma severity and abortion, while uncontrolled asthma increased the risk of a spontaneous abortion by 26% (95% CI: 14–41%) and the risk of induced abortions by 11% (95% CI: 1–21%).

LIMITATIONS, REASONS FOR CAUTION

It is possible that the study results were confounded by imbalances between groups in variables that are not recorded in the databases, but that are known to be associated with spontaneous abortions, such as alcohol consumption, obesity or maternal smoking. However, we performed sensitivity analyses which revealed that these factors are unlikely to explain the observed increased risk for a spontaneous abortion. It is also possible that women with asthma are more likely to have abortions recorded in the databases, because subjects with a chronic disease tend to visit a physician more often than those without asthma. Therefore, our odds estimates for these outcomes may be overestimated when asthmatic women were compared with non-asthmatic women. A further limitation of the study is that it would have been more appropriate to measure the severity and control of asthma only during the pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

Our cohort is less representative of women in the upper socio-economic level. This is not a threat to internal validity, but it could limit the external validity if the impact of asthma on the risk of abortion differed according to the socio-economic status of the mother. Despite the absence of supporting data, this possibility cannot be completely excluded.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Canadian Institutes of Health Research and Genentech. L.B. received research grants from Astra-Zeneca, Pfizer, sanofi-aventis, Novartis and Merck for research projects and co-chairs the Astra-Zeneca Endowment Pharmaceutical Chair in Respiratory Health. F.Z.K and A.F. have no competing interests to declare.

Source:
http://humrep.oxfordjournals.org/cgi/content/short/28/4/908?rss=1

Recommendation and review posted by G. Smith

STUDY QUESTION

Is there an association between chorionic villous vascularization, ultrasound findings and corresponding chromosome results in early miscarriage specimens from a cohort of recurrent pregnancy loss patients?

SUMMARY ANSWER

We did not find a significant difference in vascularization scores of chorionic villi between embryonic, yolk sac or empty sac miscarriages, or between euploid and noneuploid miscarriages.

WHAT IS KNOWN ALREADY

At least half of first trimester miscarriages are due to embryopathogenesis associated with chromosome errors and/or major congenital anomalies, resulting in an empty sac, a yolk sac or an embryonic miscarriage. Absent and decreased chorionic villous vascularization is usually present in these pregnancies.

STUDY DESIGN, SIZE, DURATION

For this retrospective study, 60 hematoxylin and eosin slides of miscarriage tissue of less than 10 weeks gestational age were collected from an academic institution. All patients were seen in consultation between July 2004 and October 2009.

PARTICIPANTS, SETTING, METHODS

Chorionic villous vascularization was determined using a previously published classification. The results were validated and compared with the ultrasound findings and corresponding chromosome results.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 53 embryonic miscarriages, 5 yolk sac miscarriages and 2 empty sac miscarriages. Chromosome results were obtained in 59 of the 60 miscarriages; 37.3% were euploid and 62.7% were noneuploid. Validation of the vascularization score between observers was reasonable to good (Kappa 0.47–0.76), and 59% of the cases were classified as avascular. The vascularization score did not differ between euploid or noneuploid miscarriages, or between embryonic, yolk sac or empty sac miscarriages. Avascular villi were seen more frequently in miscarriages trisomic for chromosome 16, when compared with miscarriages with other trisomies (6 out of 7 versus 8 out of 22, P = 0.04).

LIMITATIONS, REASONS FOR CAUTION

Unfortunately, the number of samples in the study was limited.

WIDER IMPLICATIONS OF THE FINDINGS

Avascular villi may indicate abnormal early placentation as a part of embryopathogenesis. Further study is warranted to determine whether a genetic cause can be found to explain these results.

Source:
http://humrep.oxfordjournals.org/cgi/content/short/28/4/916?rss=1

Recommendation and review posted by G. Smith

STUDY QUESTION

Are the fetal outcomes of singleton pregnancies that result from cleavage stage embryo transfer (ET) different from the outcomes from Day 5/6 blastocyst stage ET?

SUMMARY ANSWER

There was a significantly higher risk of preterm birth (<37 weeks) in singletons after extended embryo culture (Day 5/6) compared with cleavage stage (Day 3) transfer.

WHAT IS KNOWN ALREADY

Two recent studies, from Sweden and the USA, reported an increased risk of preterm birth in singleton pregnancies after Day 5/6 ET compared with Day 3 ET. The US study also showed increased early preterm births and the Swedish study showed increased fetal malformations in this group.

STUDY DESIGN, SIZE AND DURATION

A retrospective cohort study was performed. Data were collected from the Canadian ART Register database for all singleton births after fresh IVF/ICSI ET cycles (2001–2009).

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 12 712 singleton births were included. Of these, 9506 resulted from a Day 3 ET and 3206 resulted from a blastocyst (Day 5/6) ET.

MAIN RESULTS AND THE ROLE OF CHANCE

Preterm birth rate <37 weeks (unadjusted by potential confounding factors) was higher with Day 5/6 versus Day 3 transfers (17.2 versus 14.1%, P < 0.001). Using logistic regression analysis to adjust for confounding factors, preterm birth rate <37 weeks was the only outcome significantly increased after Day 5/6 compared with Day 3 transfer (odds ratio 1.32, 95% confidence interval 1.17–1.49). The following confounding factors were adjusted for: year of treatment (2001–2009), maternal age (continuous), parity (0 versus ≥1 birth), diagnosis category, number of oocytes retrieved [≤20 versus >20 (high responder group)], insemination method (IVF versus ICSI), number of embryos transferred (1, 2 or ≥3) and the presence of a vanishing twin (≥1 fetal heart on the initial ultrasonographic examination).

LIMITATIONS, REASONS FOR CAUTION

Post-natal follow-up studies will be required to determine if this difference we observed translates into adverse long-term effects on these offspring. The rate of early preterm births (<32 weeks) was higher in Day 5/6 versus Day 3, but the low number of cases in this category did not have the power to show a difference (3.0 versus 2.7%, P = 0.34).

WIDER IMPLICATIONS OF THE FINDINGS

We found a significantly higher risk of preterm birth (<37 weeks) in singletons after extended embryo culture (Day 5/6) compared with cleavage stage (Day 3) transfer, even when adjusting for confounding factors. Our findings are in agreement with the previous two studies; however, we did not show a difference in the very preterm deliveries (unlike the US study) or in fetal malformations (as in the Swedish study). We hypothesize that there may be a deleterious effect of prolonged in vitro embryo culture on subsequent placentation. Longer term follow-up studies will be required to determine if prolonged in vitro culture to the blastocyst stage has an adverse effect on the long-term health of offspring when compared with shorter cleavage stage culture.

STUDY FUNDING/COMPETING INTEREST(S)

None.

Source:
http://humrep.oxfordjournals.org/cgi/content/short/28/4/924?rss=1

Recommendation and review posted by G. Smith