BARD1 germline variants induce haploinsufficiency and DNA repair defects in neuroblastoma

BACKGROUND

High-risk neuroblastoma is a complex genetic disease that is lethal in more than 50% of patients despite intense multimodal therapy. Through genome-wide association studies (GWAS) and next-generation sequencing, we have identified common single nucleotide polymorphisms and rare, pathogenic or likely pathogenic germline loss-of-function variants in BARD1 enriched in neuroblastoma patients. The functional implications of these findings remain poorly understood.

METHODS

We correlated BARD1 genotype with expression in normal tissues and neuroblastomas, along with the burden of DNA damage in tumors. To validate the functional consequences of germline pathogenic or likely pathogenic BARD1 variants, we used CRISPR-Cas9 to generate isogenic neuroblastoma (IMR-5) and control (RPE1) cellular models harboring heterozygous BARD1 loss-of-function variants (R112*, R150*, E287fs, and Q564*) and quantified genomic instability in these cells via next-generation sequencing and with functional assays measuring the efficiency of DNA repair.

RESULTS

Both common and rare neuroblastoma-associated BARD1 germline variants were associated with lower levels of BARD1 mRNA and an increased burden of DNA damage. Using isogenic heterozygous BARD1 loss-of-function variant cellular models, we functionally validated this association with inefficient DNA repair. BARD1 loss-of-function variant isogenic cells exhibited reduced efficiency in repairing Cas9-induced DNA damage, ineffective RAD51 focus formation at DNA double-strand break sites, and enhanced sensitivity to cisplatin and poly (ADP-ribose) polymerase (PARP) inhibition both in vitro and in vivo.

CONCLUSIONS

Taken together, we demonstrate that germline BARD1 variants disrupt DNA repair fidelity. This is a fundamental molecular mechanism contributing to neuroblastoma initiation that may have important therapeutic implications.

Germline pathogenic variants in neuroblastoma patients are enriched in BARD1 and predict worse survival

BACKGROUND

Neuroblastoma is an embryonal cancer of the developing sympathetic nervous system. The genetic contribution of rare pathogenic or likely pathogenic germline variants in patients without a family history remains unclear.

METHODS

Germline DNA sequencing was performed on 786 neuroblastoma patients. The frequency of rare cancer predisposition gene pathogenic or likely pathogenic variants in patients was compared with 2 cancer-free control cohorts. Matched tumor DNA sequencing was evaluated for second hits, and germline DNA array data from 5585 neuroblastoma patients and 23 505 cancer-free control children were analyzed to identify rare germline copy number variants. Patients with germline pathogenic or likely pathogenic variants were compared with those without to test for association with clinical characteristics, tumor features, and survival.

RESULTS

We observed 116 pathogenic or likely pathogenic variants involving 13.9% (109 of 786) of neuroblastoma patients, representing a statistically significant excess burden compared with cancer-free participants (odds ratio [OR] = 1.60, 95% confidence interval [CI] = 1.27 to 2.00). BARD1 harbored the most statistically significant enrichment of pathogenic or likely pathogenic variants (OR = 32.30, 95% CI = 6.44 to 310.35). Rare germline copy number variants disrupting BARD1 were identified in patients but absent in cancer-free participants (OR = 29.47, 95% CI = 1.52 to 570.70). Patients harboring a germline pathogenic or likely pathogenic variant had a worse overall survival compared with those without (P = 8.6 x 10-3).

CONCLUSIONS

BARD1 is an important neuroblastoma predisposition gene harboring both common and rare germline pathogenic or likely pathogenic variations. The presence of any germline pathogenic or likely pathogenic variant in a cancer predisposition gene was independently predictive of worse overall survival. As centers move toward paired tumor-normal sequencing at diagnosis, efforts should be made to centralize data and provide an infrastructure to support cooperative longitudinal prospective studies of germline pathogenic variation.

Suprascapular nerve blockage for painful shoulder pathology - a systematic review and meta-analysis of treatment techniques

BACKGROUND

Suprascapular nerve blockade (SSNB) through injection (SSNBi) and/or pulsed radiofrequency (PRF) provide options for the management of painful shoulder pathology. Multiple techniques for delivery of SSNB are described but no consensus on optimal symptom control is available. This systematic review and meta-analysis aims to assess patient-focussed outcomes in SSNB and explore the impact of variation in the technical application of this treatment modality.

METHODS

MEDLINE, Embase and CINAHL were searched for case series, cohort studies and randomised control trials published from database inception until 28 January 2021. Articles reporting use of SSNBi or PRF for treatment of shoulder pain with a minimum 3 months follow-up were included. Patient-reported outcome measures (PROMs) were extracted and the pooled standardised mean difference (SMD), weighted by study size, was reported. Quality of methodology was assessed using Wylde's nonsummative four-point system.

FINDINGS

Of 758 references, 18 studies were included, totalling 704 SSNB. Average pain improvement at 3 months was 52.3%, with meta-analysis demonstrating a SMD of 2.37. Whereas SSNBi combined with PRF shows the greatest SMD of 2.75, this did not differ significantly from SSNBi or PRF when used as monotherapy. Location of treatment and the guidance technique used did not influence outcome.

CONCLUSION

SSNBi and PRF provide safe and effective treatment for shoulder pain, as judged by PROMs. This may be of particular value in aging or comorbid patients and with surgical restrictions during the COVID-19 pandemic. Regardless of technique, patients experience a marked improvement in pain that is maintained beyond 3 months.

Evaluating the measures in patient-reported outcomes, values and experiences (EMPROVE study): a collaborative audit of PROMs practice in orthopaedic care in the United Kingdom

INTRODUCTION

All national orthopaedic societies advocate the use of patient reported outcome measures (PROMs), but clear guidance on their use is limited. We utilised a collaborative methodology to perform a national audit aiming to assess the perceived variability in PROMs practice in orthopaedic surgery in the United Kingdom.

METHODS

A multicentre collaborative audit of practice was performed extracting PROMs data on 21 commonly performed orthopaedic procedures. For each procedure, data were collected for frequency of PROM collection, type of PROM chosen, administration intervals, method and reason for collection. Compliance with national society recommendations was undertaken.

RESULTS

Sixty-three trusts enrolled to participate in the study with a completion rate of 60% (38 trusts). The most frequently reported PROMs were those associated with best practice tariffs (83.3% and 80.6% for hip and knee replacements, respectively). Outside incentivised programmes we observed a higher rate of variation in PROMs practice which failed to meet our audit standard. Across all procedures evaluated, 69% (221/318) of respondents to the study used paper as the primary method of PROM collection.

CONCLUSIONS

This is the first national audit of PROMs collection in orthopaedics. The integration of PROMs within best practice tariff platforms positively influences the frequency and standardisation of collection. Outside this initiative, PROMS collection is infrequent and highly varied despite the presence of several registries. Because PROMs collection is a recommendation across all procedures using implantable devices, the success of this will depend on the adequacy of funding, resource delivery and the presence of clearer recommendations.

BARD1 germline variants induce haploinsufficiency and DNA repair defects in neuroblastoma

Importance

High-risk neuroblastoma is a complex genetic disease that is lethal in 50% of patients despite intense multimodal therapy. Our genome-wide association study (GWAS) identified single-nucleotide polymorphisms (SNPs) within the BARD1 gene showing the most significant enrichment in neuroblastoma patients, and also discovered pathogenic (P) or likely pathogenic (LP) rare germline loss-of-function variants in this gene. The functional implications of these findings remain poorly understood.

Objective

To define the functional relevance of BARD1 germline variation in children with neuroblastoma.

Design

We correlated BARD1 genotype with BARD1 expression in normal and tumor cells and the cellular burden of DNA damage in tumors. To validate the functional consequences of rare germline P-LP BARD1 variants, we generated isogenic cellular models harboring heterozygous BARD1 loss-of-function (LOF) variants and conducted multiple complementary assays to measure the efficiency of DNA repair.

Setting

(N/A).

Participants

(N/A).

Interventions/Exposures

(N/A).

Main Outcomes and Measures

BARD1 expression, efficiency of DNA repair, and genome-wide burden of DNA damage in neuroblastoma tumors and cellular models harboring disease-associated BARD1 germline variants.

Results

Both common and rare neuroblastoma associated BARD1 germline variants were significantly associated with lower levels of BARD1 mRNA and an increased burden of DNA damage. Using neuroblastoma cellular models engineered to harbor disease-associated heterozygous BARD1 LOF variants, we functionally validated this association with inefficient DNA repair. These BARD1 LOF variant isogenic models exhibited reduced efficiency in repairing Cas9-induced DNA damage, ineffective RAD51 focus formation at DNA doublestrand break sites, and enhanced sensitivity to cisplatin and poly-ADP ribose polymerase (PARP) inhibition.

Conclusions and Relevance

Considering that at least 1 in 10 children diagnosed with cancer carry a predicted pathogenic mutation in a cancer predisposition gene, it is critically important to understand their functional relevance. Here, we demonstrate that germline BARD1 variants disrupt DNA repair fidelity. This is a fundamental molecular mechanism contributing to neuroblastoma initiation that may have important therapeutic implications, and these findings may also extend to other cancers harboring germline variants in genes essential for DNA damage repair.

Key Points

Question: How do neuroblastoma patient BRCA1-associated RING domain 1 ( BARD1 ) germline variants impact DNA repair? Findings: Neuroblastoma-associated germline BARD1 variants disrupt DNA repair fidelity. Common risk variants correlate with decreased BARD1 expression and increased DNA double-strand breaks in neuroblastoma tumors and rare heterozygous loss-of-function variants induce BARD1 haploinsufficiency, resulting in defective DNA repair and genomic instability in neuroblastoma cellular models. Meaning: Germline variation in BARD1 contributes to neuroblastoma pathogenesis via dysregulation of critical cellular DNA repair functions, with implications for neuroblastoma treatment, risk stratification, and cancer predisposition.

Germline pathogenic variants in 786 neuroblastoma patients

Importance

Neuroblastoma accounts for 12% of childhood cancer deaths. The genetic contribution of rare pathogenic germline variation in patients without a family history remains unclear.

Objective

To define the prevalence, spectrum, and clinical significance of pathogenic germline variation in cancer predisposition genes (CPGs) in neuroblastoma patients.

Design Setting and Participants

Germline DNA sequencing was performed on the peripheral blood from 786 neuroblastoma patients unselected for family history. Rare variants mapping to CPGs were evaluated for pathogenicity and the percentage of cases harboring pathogenic (P) or likely pathogenic (LP) variants was quantified. The frequency of CPG P-LP variants in neuroblastoma cases was compared to two distinct cancer-free control cohorts to assess enrichment. Matched tumor DNA sequencing was evaluated for "second hits" at CPGs and germline DNA array data from 5,585 neuroblastoma cases and 23,505 cancer-free control children was analyzed to identify rare germline copy number variants (CNVs) affecting genes with an excess burden of P-LP variants in neuroblastoma. Neuroblastoma patients with germline P-LP variants were compared to those without P-LP variants to test for association with clinical characteristics, tumor features, and patient survival.

Main Outcomes and Measures

Rare variant prevalence, pathogenicity, enrichment, and association with clinical characteristics, tumor features, and patient survival.

Results

We observed 116 P-LP variants in CPGs involving 13.9% (109/786) of patients, representing a significant excess burden of P-LP variants compared to controls (9.1%; P = 5.14 × 10-5, Odds Ratio: 1.60, 95% confidence interval: 1.27-2.00). BARD1 harbored the most significant burden of P-LP variants compared to controls (1.0% vs. 0.03%; P = 8.18 × 10-7; Odds Ratio: 32.30, 95% confidence interval: 6.44-310.35). Rare germline CNVs disrupting BARD1 were also identified in neuroblastoma patients (0.05%) but absent in controls (P = 7.08 × 10-3; Odds Ratio: 29.47, 95% confidence interval: 1.52 - 570.70). Overall, P-LP variants in DNA repair genes in this study were enriched in cases compared to controls (8.1% vs. 5.7%; P = 0.01; Odds Ratio: 1.45, 95% confidence interval: 1.08-1.92). Neuroblastoma patients harboring a germline P-LP variant had a worse overall survival when compared to patients without P-LP variants (P = 8.6 × 10-3), and this remained significant in a multivariate Cox proportional-hazards model (P = 0.01).

Conclusions and Relevance

Neuroblastoma patients harboring germline P-LP variants in CPGs have worse overall survival and BARD1 is an important predisposition gene affected by both common and rare pathogenic variation. Germline sequencing should be performed for all neuroblastoma patients at diagnosis to inform genetic counseling and support future longitudinal and mechanistic studies. Patients with a germline P-LP variant should be closely monitored, regardless of risk group assignment.

The provision of a time-critical elective surgical service during the COVID-19 Crisis: a UK experience

INTRODUCTION

With the emergence of the COVID-19 pandemic, all elective surgery was temporarily suspended in the UK, allowing for diversion of resource to manage the anticipated surge of critically unwell patients. Continuing to deliver time-critical surgical care is important to avoid excess morbidity and mortality from pathologies unrelated to COVID-19. We describe the implementation and short-term surgical outcomes from a system to deliver time-critical elective surgical care to patients during the COVID-19 pandemic.

MATERIALS AND METHODS

A protocol for the prioritisation and safe delivery of time-critical surgery at a COVID-19 'clean' site was implemented at the Nuffield Health Exeter Hospital, an independent sector hospital in the southwest of England. Outcomes to 30 days postoperatively were recorded, including unplanned admissions after daycase surgery, readmissions and complications, as well as the incidence of perioperative COVID-19 infection in patients and staff.

RESULTS

A total of 128 surgical procedures were performed during a 31-day period by a range of specialties including breast, plastics, urology, gynaecology, vascular and cardiology. There was one unplanned admission and and two readmissions. Six complications were identified, and all were Clavien-Dindo grade 1 or 2. All 128 patients had preoperative COVID-19 swabs, one of which was positive and the patient had their surgery delayed. Ten patients were tested for COVID-19 postoperatively, with none testing positive.

CONCLUSION

This study has demonstrated the implementation of a safe system for delivery of time-critical elective surgical care at a COVID-19 clean site. Other healthcare providers may benefit from implementation of similar methodology as hospitals plan to restart elective surgery.

A novel method to test non-exclusive hypotheses applied to Arctic ice projections from dependent models

A major conundrum in climate science is how to account for dependence between climate models. This complicates interpretation of probabilistic projections derived from such models. Here we show that this problem can be addressed using a novel method to test multiple non-exclusive hypotheses, and to make predictions under such hypotheses. We apply the method to probabilistically estimate the level of global warming needed for a September ice-free Arctic, using an ensemble of historical and representative concentration pathway 8.5 emissions scenario climate model runs. We show that not accounting for model dependence can lead to biased projections. Incorporating more constraints on models may minimize the impact of neglecting model non-exclusivity. Most likely, September Arctic sea ice will effectively disappear at between approximately 2 and 2.5 K of global warming. Yet, limiting the warming to 1.5 K under the Paris agreement may not be sufficient to prevent the ice-free Arctic.

Comparative learning curves for early complications in anatomical and reverse shoulder arthroplasty

Introduction There has been a significant increase in the implantation of reverse shoulder replacements over anatomical shoulder replacements in the past five years. Few comparative data exist comparing early complication rates and learning curves. This study aimed to evaluate the early complication rates and learning curves of a single surgeon series of anatomical and reverse shoulder replacements over the first five years of independent practice. Materials and methods The first 100 anatomical and 100 reverse shoulder replacements performed between July 2011 and July 2016 were reviewed to identify early complications. Cumulative sum plots were used to analyse the learning-curve effect. Results Early complications were noted in 4 anatomical and 17 reverse shoulder replacements. One of the anatomical and ten of the reverse shoulder replacements required a return to theatre within three months. The early complication rates were observed to be significantly higher in the reverse shoulder replacement group compared with the anatomical shoulder replacement group (odds ratio 4.9; 95% confidence interval 1.6-15.2, P 1/4 0.057). An inflection point on the anatomical shoulder replacement cumulative sum plot suggestive of a trend to consistent performance was reached at 16 cases. No inflection point was observed on the reverse shoulder replacement cohort. Conclusions We observed a significantly higher early complication rate within the reverse shoulder replacement cohort, with a tenfold increase in early reoperations. In comparison to the trend seen after 16 cases for anatomical shoulder replacement, no trend was seen in the reverse shoulder replacement cohort. This either reflects the higher complication rate seen in reverse shoulder replacement or that the learning curve extends beyond 100 cases, highlighting the need for extended performance monitoring.

Exome sequencing of synchronously resected primary colorectal tumours and colorectal liver metastases to inform oncosurgical management

BACKGROUND

Next generation sequencing technology has facilitated mapping of the colorectal cancer genotype and furthered our understanding of metastogenesis. The aim of this study was to investigate for conserved and different mutations in the exomes of synchronously resected primary colorectal tumour and liver metastases. This information could potentially be utilised to guide the treatment of advanced disease with the help of biological information from the primary tumour.

METHODS

We performed exome sequencing of synchronously resected primary colorectal cancer and colorectal liver metastases as well as normal colonic mucosa and liver parenchyma, from four patients who had received neo-adjuvant chemotherapy, at a depth of 50X using the Ion Proton platform. Raw data was mapped to the reference genome prior to variant calling, annotation and downstream analysis.

RESULTS

Exome sequencing identified 585 non-synonymous missense single nucleotide variants (SNVs), of which 215 (36.8%) were unique to the primary tumour, 226 (38.6%) unique to the metastasis and 81 (13.8%) present in patient matched pairs. SNVs identified in the ErbB pathway appear to be concordant between primary and metastatic tumours.

CONCLUSION

Only 13.8% of the metastatic exome can be predicted by the genotype of the primary tumour. We have demonstrated concordance of a number of SNVs in the ErbB pathway, which may inform selection of therapeutic agents in advanced colorectal cancer.

Possible glimpses into early speciation: the effect of ovarian fluid on sperm velocity accords with post-copulatory isolation between two guppy populations

Identifying mechanisms of reproductive isolation is key to understanding speciation. Among the putative mechanisms underlying reproductive isolation, sperm-female interactions (post-mating-prezygotic barriers) are arguably the hardest to identify, not least because these are likely to operate at the cellular or molecular level. Yet sperm-female interactions offer great potential to prevent the transfer of genetic information between different populations at the initial stages of speciation. Here, we provide a preliminary test for the presence of a putative post-mating-prezygotic barrier operating between three populations of Trinidadian guppies (Poecilia reticulata), an internally fertilizing fish that inhabits streams with different levels of connectivity across Trinidad. We experimentally evaluate the effect of female ovarian fluid on sperm velocity (a predictor of competitive fertilization success) according to whether males and females were from the same (native) or different (foreign) populations. Our results reveal the potential for ovarian fluid to act as a post-mating-prezygotic barrier between two populations from different drainages, but also that the strength of this barrier is different among populations. This result may explain the previous finding that, in some populations, sperm from native males have precedence over foreign sperm, which could eventually lead to reproductive isolation between these populations.

The colonisation of the glenohumeral joint by Propionibacterium acnes is not associated with frozen shoulder but is more likely to occur after an injection into the joint

AIMS

Our aim was to investigate the prevalence of Propionibacterium (P.) acnes in the subcutaneous fat and capsule of patients undergoing shoulder surgery for frozen shoulder or instability.

PATIENTS AND METHODS

A total of 46 patients undergoing either an arthroscopic capsular release or stabilisation had biopsies taken from the subcutaneous fat and capsule of the shoulder at the time of surgery. These samples were sent for culture in enrichment, and also for Nucleic Acid Amplification testing. The prevalence of P. acnes and other microbes was recorded. Fisher's exact test of binary variables was used to calculate the association with significance set at p < 0.05. Assessment of influence of independent variables including a pre-operative glenohumeral injection, fat colonisation and gender, was undertaken using binary linear regression.

RESULTS

A total of 25 patients (53%) had P. acnes in one or more tissue samples and 35 (74%) had other bacterial species. The same microbe was found in the subcutaneous fat and the capsule in 13 patients (28%). There was no statistically significant association between the surgical pathology and capsular colonisation with P. acnes (p = 0.18) or mixed identified bacterial species (p = 0.77). Male gender was significantly associated with an increased capsular colonisation of P. acnes (odds ratio (OR) 12.38, 95% confidence interval (CI) 1.43 to 106.77, p = 0.02). A pre-operative glenohumeral injection was significantly associated with capsular P. acnes colonisation (OR 5.63, 95% CI 1.07 to 29.61, p = 0.04. Positive fat colonisation with P. acnes was significantly associated with capsular P. acnes (OR 363, 95% CI 20.90 to 6304.19, p < 0.01). Regression models pseudo R² found fat colonisation with P. acnes to explain 70% of the variance of the model. Patients who had a pre-operative glenohumeral injection who were found intra-operatively to have fat colonisation with P. acnes had a statistically significant association with colonisation of their capsule with P. acnes (OR 165, 95% CI 13.51 to 2015.24, p < 0.01).

CONCLUSION

These results show a statistically significant association between subcutaneous skin P. acnes culture and P. acnes capsular culture, especially when the patient has undergone a previous injection. The results refute the hypothesis that P. acnes causes frozen shoulder. Cite this article: Bone Joint J 2017;99-B:1067-72.

The total opportunity for sexual selection and the integration of pre- and post-mating episodes of sexual selection in a complex world

It is well known that sexual selection can target reproductive traits during successive pre- and post-mating episodes of selection. A key focus of recent studies has been to understand and quantify how these episodes of sexual selection interact to determine overall variance in reproductive success. In this article, we review empirical developments in this field but also highlight the considerable variability in patterns of pre- and post-mating sexual selection, attributable to variation in patterns of resource acquisition and allocation, ecological and social factors, genotype-by-environment interaction and possible methodological factors that might obscure such patterns. Our aim is to highlight how (co)variances in pre- and post-mating sexually selected traits can be sensitive to changes in a range of ecological and environmental variables. We argue that failure to capture this variation when quantifying the opportunity for sexual selection may lead to erroneous conclusions about the strength, direction or form of sexual selection operating on pre- and post-mating traits. Overall, we advocate for approaches that combine measures of pre- and post-mating selection across contrasting environmental or ecological gradients to better understand the dynamics of sexual selection in polyandrous species. We also discuss some directions for future research in this area.

Observational evidence confirms modelling of the long-term integrity of CO2-reservoir caprocks

Storage of anthropogenic CO₂ in geological formations relies on a caprock as the primary seal preventing buoyant super-critical CO₂ escaping. Although natural CO₂ reservoirs demonstrate that CO₂ may be stored safely for millions of years, uncertainty remains in predicting how caprocks will react with CO₂-bearing brines. This uncertainty poses a significant challenge to the risk assessment of geological carbon storage. Here we describe mineral reaction fronts in a CO₂ reservoir-caprock system exposed to CO₂ over a timescale comparable with that needed for geological carbon storage. The propagation of the reaction front is retarded by redox-sensitive mineral dissolution reactions and carbonate precipitation, which reduces its penetration into the caprock to ∼7 cm in ∼10⁵ years. This distance is an order-of-magnitude smaller than previous predictions. The results attest to the significance of transport-limited reactions to the long-term integrity of sealing behaviour in caprocks exposed to CO₂.

Anthropogenic CO₂ storage, where CO₂ is injected into saline geological resevoirs, relies on an impermeable caprock to seal in the CO₂, but caprock reaction rates to CO₂ acid brines are unclear. Here, Kampman et al. show that mineral reaction front alteration in caprocks takes place over 100,000 years.

Pathogenic FBN1 variants in familial thoracic aortic aneurysms and dissections

Marfan syndrome (MFS) due to mutations in FBN1 is a known cause of thoracic aortic aneurysms and acute aortic dissections (TAAD) associated with pleiotropic manifestations. Genetic predisposition to TAAD can also be inherited in families in the absence of syndromic features, termed familial TAAD (FTAAD), and several causative genes have been identified to date. FBN1 mutations can also be identified in FTAAD families, but the frequency of these mutations has not been established. We performed exome sequencing of 183 FTAAD families and identified pathogenic FBN1 variants in five (2.7%) of these families. We also identified eight additional FBN1 rare variants that could not be unequivocally classified as disease-causing in six families. FBN1 sequencing should be considered in individuals with FTAAD even without significant systemic features of MFS.

Testing the interactive effects of carotenoids and polyunsaturated fatty acids on ejaculate traits in the guppy Poecilia reticulata (Pisces: Poeciliidae)

Using the polyandrous livebearing guppy Poecilia reticulata, this study revealed no main effects of carotenoids in the diet on ejaculate traits, but significant main effects of polyunsaturated fatty acids (PUFAs) on sperm viability and weak but significant interacting effects of both nutrients on sperm length. Collectively, these findings not only add evidence that PUFAs are critical determinants of sperm quality, but also provide tentative evidence that for some traits these effects may be moderated by carotenoid intake.

Unifying Amplitude and Phase Analysis: A Compositional Data Approach to Functional Multivariate Mixed-Effects Modeling of Mandarin Chinese

Mandarin Chinese is characterized by being a tonal language; the pitch (or F0) of its utterances carries considerable linguistic information. However, speech samples from different individuals are subject to changes in amplitude and phase, which must be accounted for in any analysis that attempts to provide a linguistically meaningful description of the language. A joint model for amplitude, phase, and duration is presented, which combines elements from functional data analysis, compositional data analysis, and linear mixed effects models. By decomposing functions via a functional principal component analysis, and connecting registration functions to compositional data analysis, a joint multivariate mixed effect model can be formulated, which gives insights into the relationship between the different modes of variation as well as their dependence on linguistic and nonlinguistic covariates. The model is applied to the COSPRO-1 dataset, a comprehensive database of spoken Taiwanese Mandarin, containing approximately 50,000 phonetically diverse sample F0 contours (syllables), and reveals that phonetic information is jointly carried by both amplitude and phase variation. Supplementary materials for this article are available online.

Postcopulatory inbreeding avoidance in guppies

In many species, the negative fitness effects of inbreeding have facilitated the evolution of a wide range of inbreeding avoidance mechanisms. Although avoidance mechanisms operating prior to mating are well documented, evidence for postcopulatory mechanisms of inbreeding avoidance remain scarce. Here, we examine the potential for paternity biases to favour unrelated males when their sperm compete for fertilizations though postcopulatory inbreeding avoidance mechanisms in the guppy, Poecilia reticulata. To test this possibility, we used a series of artificial inseminations to deliver an equal number of sperm from a related (either full sibling or half sibling) and unrelated male to a female while statistically controlling for differences in sperm quality between rival ejaculates. In this way, we were able to focus exclusively on postcopulatory mechanisms of inbreeding avoidance and account for differences in sperm competitiveness between rival males. Under these carefully controlled conditions, we report a significant bias in paternity towards unrelated males, although this effect was only apparent when the related male was a full sibling. We also show that sperm competition generally favours males with highly viable sperm and thus that some variance in sperm competitiveness can be attributed to difference in sperm quality. Our findings for postcopulatory inbreeding avoidance are consistent with prior work on guppies, revealing that sperm competition success declines linearly with the level of relatedness, but also that such effects are only apparent at relatedness levels of full siblings or higher. These findings reveal that postcopulatory processes alone can facilitate inbreeding avoidance.

Genetic variation underlies temperature tolerance of embryos in the sea urchin Heliocidaris erythrogramma armigera

Ocean warming can alter natural selection on marine systems, and in many cases, the long-term persistence of affected populations will depend on genetic adaptation. In this study, we assess the potential for adaptation in the sea urchin Heliocidaris erythrogramma armigera, an Australian endemic, that is experiencing unprecedented increases in ocean temperatures. We used a factorial breeding design to assess the level of heritable variation in larval hatching success at two temperatures. Fertilized eggs from each full-sibling family were tested at 22 °C (current spawning temperature) and 25 °C (upper limit of predicted warming this century). Hatching success was significantly lower at higher temperatures, confirming that ocean warming is likely to exert selection on this life-history stage. Our analyses revealed significant additive genetic variance and genotype-by-environment interactions underlying hatching success. Consistent with prior work, we detected significant nonadditive (sire-by-dam) variance in hatching success, but additionally found that these interactions were modified by temperature. Although these findings suggest the potential for genetic adaptation, any evolutionary responses are likely to be influenced (and possibly constrained) by complex genotype-by-environment and sire-by-dam interactions and will additionally depend on patterns of genetic covariation with other fitness traits.

Abstract MS3-3: Navigating the Genome: Quandaries and Approaches to Dealing with Genomic Information

Recent technological advances have made large-scale DNA sequencing, including whole genome sequencing, a practical reality. The ability to sequence tumor genomes as well as the germ-line genome of individuals holds considerable promise for the practice of oncology. Broad assessment of cancer risk in individuals, identification of those at extreme risk for cancer who might benefit from specific interventions and pharmacogenomic guidance regarding therapy are possible benefits of assessing an individual's genome. Likewise, analysis of genomic information in tumors is poised to begin helping to guide highly specific treatment of cancer in an increasingly individualized manner.

However, as the field of oncology begins to use genomic queries to assess patient risk, characterize disease and guide treatment, many challenges must be addressed. Purely technical issues include the suboptimal accuracy of current platforms for massively parallel sequencing, tumor heterogeneity and difficulties interpreting genomic risk information in a clinically relevant manner. Systemic challenges include how to interpret, store and present massive amounts of genomic data in the currently highly fragmented (and limited) electronic medical record. Finally, in the process of genome-scale sequencing vast numbers of incidental results are inevitably generated, which may have important ramifications for patients and providers but may be unwelcome. Such ethical, legal and social implications of whole genome sequencing raise significant questions about patient autonomy, the physician's duty to warn and the laboratory's duty to report a wide variety of highly heterogeneous genomic findings. In this presentation some of these salient issues and possible solutions will be explored.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr MS3-3.

Applying Genomic Analysis to Newborn Screening

Large-scale genomic analysis such as whole-exome and whole-genome sequencing is becoming increasingly prevalent in the research arena. Clinically, many potential uses of this technology have been proposed. One such application is the extension or augmentation of newborn screening. In order to explore this application, we examined data from 3 children with normal newborn screens who underwent whole-exome sequencing as part of research participation. We analyzed sequence information for 151 selected genes associated with conditions ascertained by newborn screening. We compared findings with publicly available databases and results from over 500 individuals who underwent whole-exome sequencing at the same facility. Novel variants were confirmed through bidirectional dideoxynucleotide sequencing. High-density microarrays (Illumina Omni1-Quad) were also performed to detect potential copy number variations affecting these genes. We detected an average of 87 genetic variants per individual. After excluding artifacts, 96% of the variants were found to be reported in public databases and have no evidence of pathogenicity. No variants were identified that would predict disease in the tested individuals, which is in accordance with their normal newborn screens. However, we identified 6 previously reported variants and 2 novel variants that, according to published literature, could result in affected offspring if the reproductive partner were also a mutation carrier; other specific molecular findings highlight additional means by which genomic testing could augment newborn screening.

Assessing the potential for post-copulatory sexual selection in elasmobranchs

This review highlights the potential role that post-copulatory sexual selection plays in elasmobranch reproductive systems and the utility of this group to further understanding of evolutionary responses to the post-copulatory processes of sperm competition and cryptic female choice. The growing genetic evidence for female multiple mating (polyandry) in elasmobranchs is summarized. While polyandry appears to be common in this group, rates of multiple paternity are highly variable between species suggesting that there is large variance in the strength of post-copulatory sexual selection among elasmobranchs. Possible adaptations of traits important for post-copulatory sexual selection are then considered. Particular emphasis is devoted to explore the potential for sperm competition and cryptic female choice to influence the evolution of testes size, sperm morphology, genital morphology and sperm storage organs. Finally, it is argued that future work should take advantage of the wealth of information on these reproductive traits already available in elasmobranchs to gain a better understanding of how post-copulatory sexual selection operates in this group.

Assessing the potential for post-copulatory sexual selection in elasmobranchs

This review highlights the potential role that post-copulatory sexual selection plays in elasmobranch reproductive systems and the utility of this group to further understanding of evolutionary responses to the post-copulatory processes of sperm competition and cryptic female choice. The growing genetic evidence for female multiple mating (polyandry) in elasmobranchs is summarized. While polyandry appears to be common in this group, rates of multiple paternity are highly variable between species suggesting that there is large variance in the strength of post-copulatory sexual selection among elasmobranchs. Possible adaptations of traits important for post-copulatory sexual selection are then considered. Particular emphasis is devoted to explore the potential for sperm competition and cryptic female choice to influence the evolution of testes size, sperm morphology, genital morphology and sperm storage organs. Finally, it is argued that future work should take advantage of the wealth of information on these reproductive traits already available in elasmobranchs to gain a better understanding of how post-copulatory sexual selection operates in this group.

Experimental evidence that high levels of inbreeding depress sperm competitiveness

The effects of inbreeding on sperm quantity and quality are among the most dramatic examples of inbreeding depression. The extent to which inbreeding depression results in decreased fertilization success of a male's sperm, however, remains largely unknown. This task is made more difficult by the fact that other factors, such as cryptic female choice, male sperm allocation and mating order, can also drive patterns of paternity. Here, we use artificial insemination to eliminate these extraneous sources of variation and to measure the effects of inbreeding on the competitiveness of a male's sperm. We simultaneously inseminated female guppies (Poecilia reticulata) with equal amounts of sperm from an outbred (f = 0) male and either a highly (f = 0.59) or a moderately inbred (f = 0.25) male. Highly inbred males sired significantly fewer offspring than outbred males, but share of paternity did not differ between moderately inbred and outbred males. These findings therefore confirm that severe inbreeding can impair the competitiveness of sperm, but suggest that in the focal population inbreeding at order of a brother-sister mating does not reduce a male's sperm competitiveness.

Physical profiles of elite male field hockey and soccer players - application to sport-specific tests

Background. The physical demands of field hockey and soccer, based on match analysis, are comparable. As a consequence many exercise scientists and coaches have started to use the same type of field tests for hockey and soccer for the purposes of talent identification and training prescription. The validity of this practice is unknown and the data supporting the similarity of the physical attributes of soccer and hockey players are lacking. Objectives. To compare the physical attributes of elite South African hockey and soccer players. Methods. Elite hockey players (N=39: 22±3 years; mean ± standard deviation) and soccer players (N=37; 24±4 years) completed a set of physical tests including a 10 m and 40 m sprint test, a repeated sprint test (sprint fatigue resistance), a 1RM bench press and a push-up test. Results. There were no differences in the 10 m (1.8±0.1 s both groups) and 40 m (5.4±0.2 s v. 5.3±0.2 s; hockey v. soccer) sprint times and distance run in the repeated sprint test (754±14 m v. 734±51 m). The hockey players were stronger (82±16 v. 65±13 kg) and did more push-ups (49±12 v. 38±10 push-ups) than the soccer players. Conclusions. It is acceptable to use the same type of sport-specific tests to measure sprint capacity and sprint fatigue resistance for hockey and soccer players. However, it is questionable whether the normative data derived for upper body strength for soccer players are relevant for hockey players, and vice versa. South African Journal of Sports Medicine Vol. 19 (3) 2007: pp. 74-78

Physical profiles of elite male field hockey and soccer players - application to sport-specific tests

Background. The physical demands of field hockey and soccer, based on match analysis, are comparable. As a consequence many exercise scientists and coaches have started to use the same type of field tests for hockey and soccer for the purposes of talent identification and training prescription. The validity of this practice is unknown and the data supporting the similarity of the physical attributes of soccer and hockey players are lacking. Objectives. To compare the physical attributes of elite South African hockey and soccer players. Methods. Elite hockey players (N=39: 22±3 years; mean ± standard deviation) and soccer players (N=37; 24±4 years) completed a set of physical tests including a 10 m and 40 m sprint test, a repeated sprint test (sprint fatigue resistance), a 1RM bench press and a push-up test. Results. There were no differences in the 10 m (1.8±0.1 s both groups) and 40 m (5.4±0.2 s v. 5.3±0.2 s; hockey v. soccer) sprint times and distance run in the repeated sprint test (754±14 m v. 734±51 m). The hockey players were stronger (82±16 v. 65±13 kg) and did more push-ups (49±12 v. 38±10 push-ups) than the soccer players. Conclusions. It is acceptable to use the same type of sport-specific tests to measure sprint capacity and sprint fatigue resistance for hockey and soccer players. However, it is questionable whether the normative data derived for upper body strength for soccer players are relevant for hockey players, and vice versa. South African Journal of Sports Medicine Vol. 19 (3) 2007: pp. 74-78

Colourful male guppies produce faster and more viable sperm

In guppies (Poecilia reticulata) precopulatory sexual selection (via female choice) and post-copulatory selection (via sperm competition) both favour males with relatively high levels of carotenoid (orange) pigmentation, suggesting that colourful males produce more competitive ejaculates. Here we test whether there is a positive association between male orange pigmentation and sperm quality. Our analysis of sperm quality focused on sperm swimming speeds (using CASA: computer-assisted sperm analysis to estimate three parameters of sperm velocity in vitro), sperm viability (proportion of live sperm per stripped ejaculate) and sperm lengths. We found that males with relatively large areas of orange pigmentation had significantly faster and more viable sperm than their less ornamented counterparts, suggesting a possible link between dietary carotenoid intake and sperm quality. By contrast, we found no relationship between sperm length (head length and total sperm length) and male phenotype. These findings, in conjunction with previous work showing that highly ornamented male guppies sire higher quality offspring, suggest that female preference for colourful males and sperm competition work in concert to favour intrinsically higher quality males.

Polymorphisms in the VKORC1 gene are strongly associated with warfarin dosage requirements in patients receiving anticoagulation

BACKGROUND

Warfarin is a mainstay of therapy for conditions associated with an increased risk of thromboembolic events. However, the use of this common agent is fraught with complications and little is known regarding inter-individual variation in warfarin response.

OBJECTIVE

We tested for association between single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 and average weekly warfarin dose required to maintain patients at their desired anticoagulation target.

METHODS

The sample consisted of 93 European-American patients from anticoagulation clinics at the University of North Carolina at Chapel Hill. Data on mean weekly warfarin dose were collected over a mean treatment period of 20.6 months. ANCOVA models were used and haplotype analysis was performed.

RESULTS

Three of six VKORC1 SNPs were found to be very strongly associated with the average warfarin dose required to achieve the target international normalised ratio (INR; p<0.0001). The mean weekly dose by genotype ranged from approximately 27 to 47 mg. There was no evidence for an association between either of the two CYP2C9 polymorphisms studied, CYP2C9*2 and CYP2C9*3. CYP2C9*3 was significantly (p = 0.05) associated with average warfarin dosage after adjustment for VKORC1*1173.

CONCLUSIONS

These results are of considerable clinical interest and confirm recently published results regarding the role of these two genes in modifying warfarin metabolism and maintenance dosage. The consistent findings regarding the role of VKORC1 and CYP2C9 in warfarin metabolism and maintenance dosage represent a clinically useful proof of principal for the use of pharmacogenomic information in medicine and may lead to improved understanding of warfarin's actions.

Does egg competition occur in marine broadcast-spawners?

When the availability of sperm limits female reproductive success, competition for sperm, may be an important broker of sexual selection. This is because sperm limitation can increase the variance in female reproductive success, resulting in strong selection on females to compete for limited fertilization opportunities. Sperm limitation is probably common in broadcast-spawning marine invertebrates, making these excellent candidates for investigating scramble competition between broods of eggs and its consequences for female reproductive success. Here, we report our findings from a series of experiments that investigate egg competition in the sessile, broadcast-spawning polychaete Galeolaria caespitosa. We initially tested whether the order in which eggs encounter sperm affects their fertilization success at two ecologically relevant current regimes. We used a split-clutch-split--ejaculate technique to compare the fertilization success of eggs from individual females that had either first access (competition-free treatment) or second access (egg competition treatment) to a batch of sperm. We found that fertilization success depended on the order in which eggs accessed sperm; eggs that were assigned to the competition-free treatment exhibited significantly higher fertilization rates than those assigned to the egg competition treatment at both current speeds. In subsequent experiments we found that prior exposure of sperm to eggs significantly reduced both the quantity and quality of sperm available to fertilize a second clutch of eggs, resulting in reductions in fertilization success at high and low sperm concentrations. These findings suggest that female traits that increase the likelihood of sperm-egg interactions (e.g. egg size) will respond to selection imposed by egg competition.

The benefits of polyandry in the free-spawning polychaete Galeolaria caespitosa

In many species, females are thought to benefit from polyandry due to the reduced risks of fertilization by genetically incompatible sperm. However, few studies that have reported such benefits have directly attributed variation in female reproductive success to the interacting effects of males and females at fertilization. In this paper, we determine whether male x female interactions influence fertilization in vitro in the free-spawning, sessile polychaete Galeolaria caespitosa. Furthermore, we determined whether polyandry results in direct fertilization benefits for females by experimentally manipulating the number of males contributing towards staged spawning events. To test for male x female interaction effects we performed an initial experiment that crossed seven males with six females (in all 42 combinations), enabling us to assess fertilization rates for each specific male-female pairing and attribute variation in fertilization success to males, females and their interaction. This initial experiment revealed a strong interaction between males and females at fertilization, confirming that certain male-female combinations were more compatible than others. A second experiment tested the hypothesis that polyandry enhances female reproductive success by exposing each female's eggs to either a single male's sperm (monandry) or the sperm from three males simultaneously (polyandry). We performed this second experiment at two ecologically relevant sperm concentrations. This latter experiment revealed a strong fertilization benefit of polyandry, independent of the effects of sperm concentration (which were also significant). We suggest that these direct fertilization gains arising from polyandry will constitute an important source of selection on females to mate multiply in nature.

Revising the troublesome stoma: combined abdominal wall recontouring and revision of stomas

PURPOSE

Despite preoperative siting and maturation of stomas, some patients may have poor stoma function because of redundant pannus, scars, creases, and parastomal or incisional hernias. In these patients, a combined abdominoplasty and stoma revision may be helpful. The object of this manuscript is to report our preliminary results.

METHODS

Eight patients (mean age, 48 years; female/male ratio, 7/1) undergoing this procedure are reported. Five patients had inflammatory bowel disease, two had malignancies, and one had multiple sclerosis with bladder and bowel involvement. Patients were contacted at two months to two years follow-up to assess functional outcome and satisfaction with the procedure.

RESULTS

Indications for surgery were difficulty maintaining an appliance (n = 7), frequent stool leakage (n = 6), and skin irritation (n = 4). Multiple surgeries (n = 4), skin creases (n = 3), scarring (n = 2), large weight loss (n = 4), and hernias (n = 5) were contributing factors. At surgery five patients had hernias repaired (3 parastomal, 2 incisional), three had stomas resited, and three underwent resections for Crohn's disease. One patient developed a seroma postoperatively. At follow-up six patients were able to maintain an appliance for at least four days, whereas one changed the appliance every three days because of personal preference. None experience stool leakage. All reported a dramatic improvement in body image.

CONCLUSION

Combined stoma revision and abdominoplasty can be performed safely and leads to improved functional results and outcome.

Disrupted sperm function and fertilin beta processing in mice deficient in the inositol polyphosphate 5-phosphatase Inpp5b

Inpp5b is an ubiquitously expressed type II inositol polyphosphate 5-phosphatase. We have disrupted the Inpp5b gene in mice and found that homozygous mutant males are infertile. Here we examine the causes for the infertility in detail. We demonstrate that sperm from Inpp5b(-/-) males have reduced motility and reduced ability to fertilize eggs, although capacitation and acrosome exocytosis appear to be normal. In addition, fertilin beta, a sperm surface protein involved in sperm-egg membrane interactions that is normally proteolytically processed during sperm transit through the epididymis, showed reduced levels of processing in the Inpp5b(-/-) animals. Inpp5b was expressed in the Sertoli cells and epididymis and at low levels in the developing germ cells; however, mice lacking Inpp5b in spermatids and not in other cell types generated by conditional gene targeting, were fully fertile. The abnormalities in mutant sperm function and maturation appear to arise from defects in the functioning of Sertoli and epididymal epithelial cells. Our results directly demonstrate a previously unknown role for phosphoinositides in normal sperm maturation beyond their previously characterized involvement in the acrosome reaction. Inpp5b(-/-) mice provide an excellent model to study the role of Sertoli and epididymal epithelial cells in the differentiation and maturation of sperm.

Analysis of fertilin alpha (ADAM1)-mediated sperm-egg cell adhesion during fertilization and identification of an adhesion-mediating sequence in the disintegrin-like domain

Fertilin alpha (also known as ADAM1) is a member of the ADAM (A disintegrin and A metalloprotease domain) family of proteins. In this study, we examine the mechanism of mouse fertilin alpha's in adhesion of sperm to the egg plasma membrane during fertilization. We find that recombinant forms of fertilin alpha corresponding to either the disintegrin-like domain or the cysteine-rich domain and the EGF-like repeat can perturb sperm-egg binding, suggesting that both of these domains can participate in fertilin alpha-mediated adhesion events. In further examination of the fertilin alpha disintegrin-like domain, we find that a subdomain of disintegrin-like domain with the sequence DLEECDCG outside the putative disintegrin loop but with homology to the fertilin beta disintegrin loop can inhibit the binding of both sperm and recombinant fertilin alpha to eggs, suggesting that this is an adhesion-mediating motif of the fertilin alpha disintegrin-like domain. This sequence also inhibits the binding of recombinant fertilin beta to eggs and thus is the first peptide sequence found to block two different sperm ligands. Finally, a monoclonal antibody to the tetraspanin protein CD9, KMC.8, inhibited the binding of recombinant fertilin alpha to eggs in one type of binding assay, suggesting that, under certain conditions, fertilin alpha may interact with a KMC.8-sensitive binding site on the egg plasma membrane.

Fertilin beta and other ADAMs as integrin ligands: insights into cell adhesion and fertilization

One of the most important cell-cell interactions is that of the sperm with the egg. This interaction, which begins with cell adhesion and culminates with membrane fusion, is mediated by multiple molecules on the gametes. One of the best-characterized of these molecules is fertilin beta, a ligand on mammalian sperm and one of the first ADAMs (A Disintegrin and A Metalloprotease domain) to be identified. Fertilin beta (also known as ADAM2) participates in sperm-egg membrane binding, and it has long been hypothesized that this function is achieved through the interaction of the disintegrin domain of fertilin beta with an integrin on the egg surface. There are now approximately 30 members of the ADAM family and, to date, five different ADAMs (fertilin beta, ADAM9, ADAM12, ADAM15, ADAM23) have been described to interact with integrins (specifically alpha(6)beta(1), alpha(v)beta(3), alpha(9)beta(1), alpha(v)beta(5), and/or alpha(5)beta(1)). This field will be discussed with respect to what is known about specific ADAMs and the integrins with which they interact, and what the implications are for sperm-egg interactions and for integrin function. These data will also be discussed in the context of recent knockout studies, which show that eggs lacking the alpha(6) integrin subunit can be fertilized, and eggs lacking the integrin-associated tetraspanin protein CD9 fail to fertilize. Key issues in cell adhesion that pertain to gametes and fertilization will also be highlighted.

Nocturnal hypoxaemia and central-nervous-system events in sickle-cell disease

BACKGROUND

Central-nervous-system (CNS) events, including strokes, transient ischaemic attacks, and seizures are common in sickle-cell disease. Stroke can be predicted by high velocities in the internal-carotid or middle-cerebral arteries on transcranial doppler ultrasonography. We tested the hypothesis that nocturnal hypoxaemia can predict CNS events better than clinical or haematological features, or transcranial doppler sonography.

METHODS

We screened 95 hospital-based patients with sickle-cell disease (median age 7.7 years [range 1.0-23.1]), but without previous stroke, with transcranial doppler and overnight pulse oximetry. Follow-up continued for a median of 6.01 (0.11-8.54) years.

FINDINGS

19 patients had CNS events (six ischaemic and one haemorrhagic stroke, eight transient ischaemic attacks, and four seizures). Mean overnight oxygen saturation ([SaO(2)] hazard ratio 0.82 per 1% increase [95% CI 0.71-0.93]; p=0.003) and higher internal-carotid or middle-cerebral artery velocity (1.02 for every increase of 1 cm/s [1.004-1.03]; p=0.009) were independently associated with time to CNS event. After accounting for mean SaO(2), artery velocity, and haemoglobinopathy, high haemoglobin concentration was also associated with an increased risk of CNS event (1.7 per g/dL, [1.18-2.43]; p=0.004). Dips suggestive of obstructive sleep apnoea did not predict CNS events, and adenotonsillectomy seemed to have no effect, although the CI were wide and clinically important effects cannot be excluded.

INTERPRETATION

Screening for, and appropriate management of, nocturnal hypoxaemia might be a safe and effective alternative to prophylactic blood transfusion for primary prevention of CNS events in sickle-cell disease.

Patterns of sperm precedence and predictors of paternity in the Trinidadian guppy

Despite its widespread occurrence in animals, sperm competition has been studied in a limited range of taxa. Among the most neglected groups in this respect are internally fertilizing fish in which virtually nothing is known about the dynamics of sperm competition. In this study, we examined the outcome of sperm competition when virgin female guppies mated with two males. Behavioural cues were used to ensure that each male mated once (with female cooperation) and that sperm were successfully inseminated at copulation. Two polymorphic microsatellite loci were used to estimate the proportion of offspring sired by the second male (P2) and the results revealed a bimodal distribution with either first or (more often) second male priority The observed P2 distribution differed from that expected under the 'fair raffle' model of sperm competition. Random sperm mixing is therefore unlikely to account for the observed variance in P2 in this study. A further aim of our study was to identify predictors of male reproductive success. Using logistic linear modelling, we found that the best predictors of paternity were time to remating and the difference in courtship display rate between first and second males. Males that mated quickly and performed relatively high numbers of sigmoid displays obtained greater parentage than their slower and less vigorous counterparts. Since females are attracted to high-displaying males, our results suggest that female choice may facilitate sperm competition and/or sperm choice in guppies.

Platelet and leucocyte activation in childhood sickle cell disease: association with nocturnal hypoxaemia

We hypothesized that vaso-occlusive events in childhood sickle cell disease (SCD) may relate to inflammatory cell activation as well as interactions between sickle erythrocytes and vascular endothelium. Peripheral blood was examined from 24 children with SCD, of whom 12 had neurological sequelae and seven had frequent painful crises, and 10 control subjects. Platelet (CD62P and CD40L expression) and granulocyte (CD11b expression) activation and levels of platelet-erythrocyte and platelet-granulocyte complexes were determined by flow cytometry. Platelets (P = 0.019), neutrophils (P = 0.02) and monocytes (P = 0.001) were more activated and there were increased platelet-erythrocyte complexes (P = 0.026) in SCD patients compared with controls. Platelet-granulocyte complexes were not raised. There were no differences between the different groups of SCD. As hypoxia activates monocytes, platelets and endothelial cells and causes sickling of SCD erythrocytes, we also investigated 20 SCD patients with overnight pulse oximetry. Minimum overnight saturation correlated with the level of platelet-erythrocyte complexes (Spearman's rho -0.668, P < 0.02), neutrophil CD11b (Spearman's rho -0.466, P = 0.038) and monocyte CD11b (Spearman's rho -0.652, P = 0. 002). These findings provide important clues about the mechanism by which SCD patients may become predisposed to vaso-occlusive events.

Multiple benefits of multiple mating in guppies

The rewards of promiscuity for males are undisputed. But why should a female mate promiscuously, particularly when her partners offer no resources other than sperm and increase her chances of succumbing to predation or disease? This question has been hotly debated but at present remains largely unresolved [Jennions, M. D. & Petrie, M. (2000) Biol. Rev. 75, 21-64]. One possibility is that females exploit postcopulatory mechanisms, such as sperm competition, to increase both the quality and quantity of their offspring. In this paper, we use the Trinidadian guppy, a species with a resource-free mating system, to test the hypothesis that females gain multiple benefits from multiple mating. Our results indicate that multiply mated females secure substantive advantages: They have shorter gestation times and larger broods, and they produce offspring with better developed schooling abilities and escape responses than their singly mated counterparts.

Getting sperm and egg together: things conserved and things diverged

Sperm-egg interactions occur at multiple levels on the egg surface, first with the egg's extracellular matrix and then with the egg's plasma membrane. The BioPore minisymposium on "The Egg Surface" at the 1999 annual meeting of the Society for the Study of Reproduction highlighted a series of events underlying successful interactions of the sperm with the egg: 1) composition, synthesis, and assembly of the mouse egg's extracellular matrix, the zona pellucida, during oogenesis; 2) oocyte maturation and development of the sperm-binding domain of mouse eggs; and 3) characterization of functional domains in different sperm ligands (fertilin-alpha and fertilin-beta in the mouse and lysin in the abalone) that recognize cognate binding sites on the egg surface. Data that were presented are reviewed here and discussed with respect to conserved and divergent features of gamete functions.

Identification of key functional amino acids of the mouse fertilin beta (ADAM2) disintegrin loop for cell-cell adhesion during fertilization

Fertilin beta (also known as ADAM2) is a cell adhesion molecule on the surface of mammalian sperm that participates in sperm-egg membrane binding. Fertilin beta is a member of the molecular family known as ADAMs or MDCs. These proteins have a disintegrin domain with homology to integrin ligands found in snake venoms; several of these snake proteins have an RGD tripeptide presented on an extended "disintegrin loop." However, fertilin beta lacks an RGD tripeptide and instead has the consensus sequence X(D/E)ECD (QDECD in mouse fertilin beta) in its putative disintegrin loop, and there is controversy over which amino acids comprise the active site of the fertilin beta disintegrin loop. We have used point-mutated versions of the sequence AQDECDVT and two bioassays to identify the key functional amino acids of this sequence from the mouse fertilin beta disintegrin domain. Amino acid substitutions for the terminal aspartic acid residue of the QDECD sequence result in dramatically reduced activities in the two assays for protein function, implicating the terminal aspartic acid residue as critical for protein function. Substitutions for the glutamic acid and the cysteine residues in the QDECD sequence result in slight reductions in activity, whereas substitution of the first aspartic acid has virtually no effect. These data suggest that the conserved ECD sequence of the mouse fertilin beta disintegrin loop, especially the terminal D residue, contributes more to the protein's activity than does the QDE sequence that aligns with the RGD tripeptide in other disintegrins.

Effects of perturbation of cell polarity on molecular markers of sperm-egg binding sites on mouse eggs

The mouse germinal vesicle (GV)-intact oocyte is a symmetric cell, with the GV centrally localized and with components of the plasma membrane and cortex symmetrically distributed around the periphery of the oocyte. During oocyte maturation, two distinct regions of the egg plasma membrane and cortex develop: the amicrovillar region overlying the meiotic spindle and the microvillar region. The development of this polarity is significant, since sperm bind to and fuse with the microvillar region. We are interested in the development of egg polarity and have characterized the localizations of several markers for egg polarity in normal metaphase II eggs and GV-intact oocytes. The asymmetric distributions of these markers (including actin, cortical granules, binding sites for the sperm proteins fertilin alpha and fertilin beta, and two different beta(1) integrin epitopes) develop during oocyte maturation in vitro, and this polarity can be perturbed by treatments that disrupt the actin microfilaments or microtubules. In addition, immunoelectron microscopy reveals that binding sites for recombinant fertilin beta are specifically localized to the microvillar region, suggesting that the binding sites for this sperm ligand are either specifically localized or activated in this region. These results indicate that structural remodeling of the mouse egg plasma membrane is accompanied by molecular remodeling, resulting in the localization or activation of specific molecules in subdomains of the plasma membrane.

Male mating behaviour and sperm production characteristics under varying sperm competition risk in guppies

Since natural populations of guppies, Poecilia reticulata, often differ from one another in social structure, the intensity of sperm competition is likely to vary between localities. Guppies are promiscuous, with female choice for colourful males playing a central role in the mating system. In addition, male guppies use forced copulations to circumvent female choice. Both methods of copulation are used interchangeably by individual males, but the degree to which either is used may depend on the social environment into which males are born. Here we show that male mating behaviour varies according to the rearing sex ratio: when reared in male-biased groups, males performed more forced copulations and fewer courtship displays but showed the opposite pattern of behaviour when reared in female-biased groups. Our prediction, based on sperm competition theory, that stripped sperm number would reflect social structure was not supported by our results. Instead, the overall level of sexual activity (gonopodial thrusts+sigmoid displays) was a better predictor of sperm number in the different groups of males. Rearing density, where sex ratio was controlled, did not significantly affect male mating behaviour or sperm traits. Males reared under the different sex ratios continued to show their characteristic behaviour patterns when placed in equal sex ratio tanks. We conclude, therefore, that males adopt mating strategies to suit their social environment, and that these strategies remain fixed, for short periods at least, if population structure changes. Copyright 1999 The Association for the Study of Animal Behaviour.

Improved prognosis for acquired aplastic anaemia

This study compared the prognosis of patients treated for aplastic anaemia at Great Ormond Street Hospital for Children from 1973-88 (group A; n = 38) with a more recent cohort from 1989-96 (group B; n = 37). The two groups were similar in terms of clinical history, age, and severity of aplasia. The main treatment differences included the use of androgen treatment in group A (21 of 38 patients) but not in group B, and the addition of cyclosporin A to immunosuppressive treatment for 14 patients in group B. Actuarial survival at eight years' follow up was significantly better for group B (84%; 95% CI, 68% to 93%) than for group A (45%; 95% CI, 30% to 60%), because of improved outcome for both immunosuppressive treatment (86% v 39%) and bone marrow transplantation (93% v 56%). There was no evidence for late clonal disorders or secondary malignancies in survivors in either group. The prognosis for aplastic anaemia has improved greatly in recent years so that over 80% of children are long term survivors.

Transport of a series of D-phenylalanine-glycine hexapeptides across rat alveolar epithelia in vitro

The effect of lipophilicity on the absorption of peptides from the lungs was investigated. D-phenylalanine (F)-glycine (G) hexapeptides were synthesised to differ, predominantly, only in their lipophilicity. Rat alveolar type II cells were isolated and cultured on plastic, or polycarbonate filters; by day 6 they had de-differentiated to an alveolar type I-like epithelium. The permeability of the monolayers to the hexapeptides was determined. The hexapeptides were metabolically and chemically stable for greater than 24h in the presence of the cells. They did not adhere to the cell culture plastic and were associated only to a low extent with the cell monolayer. The apical to basolateral permeability coefficients for D-F1G5, D-F2G4, and D-F3G3 were 2.19+/-0.53, 1.75+/-0.42 and 2.20+/-0.56 x 10(-7) cm s(-1) respectively. The permeability of the monolayers to D-F1G5 and D-F2G4 was concentration and direction independent, however for D-F3G3 the monolayer was more permeable in the basolateral to apical direction. There was no correlation between the lipophilicity of the hexapeptides and permeability coefficients: other physicochemical parameters did not predict hexapeptide transport. Lipophilicity does not appear to control the transport of hexapeptides across the alveolar epithelium probably as a consequence of the peptides being transported via the paracellular route.