Notch signaling augments the canonical Wnt pathway to specify the size of the otic placode

The inner ear derives from a patch of ectoderm defined by expression of the transcription factor Pax2. We recently showed that this Pax2^+ ectoderm gives rise not only to the otic placode but also to the surrounding cranial epidermis, and that Wnt signaling mediates this placode-epidermis fate decision. We now present evidence for reciprocal interactions between the Wnt and Notch signaling pathways during inner ear induction. Activation of Notch1 in Pax2+ ectoderm expands the placodal epithelium at the expense of cranial epidermis, whereas loss of Notch1 leads to a reduction in the size of the otic placode. We show that Wnt signaling positively regulates Notch pathway genes such as Jag1, Notch1 and Hes1, and we have used transgenic Wnt reporter mice to show that Notch signaling can modulate the canonical Wnt pathway. Gain- and loss-of-function mutations in the Notch and Wnt pathways reveal that some aspects of otic placode development - such as Pax8 expression and the morphological thickening of the placode - can be regulated independently by either Notch or Wnt signals. Our results suggest that Wnt signaling specifies the size of the otic placode in two ways, by directly upregulating a subset of otic genes, and by positively regulating components of the Notch signaling pathway, which then act to augment Wnt signaling

Investigating the basis of sexual dysfunction during late-onset hypogonadism

Late-onset hypogonadism (LOH) is the term used to describe the decline in serum testosterone levels associated with increasing age in men above 40 years. A number of symptoms are attributed to LOH, but the most common association is that of sexual dysfunction. LOH has recently come under greater scrutiny with the widespread use of testosterone therapy, and concerns regarding the efficacy and safety of testosterone replacement therapy have been raised. In particular, the cardiovascular safety and the beneficial effects of testosterone replacement therapy on general health have been questioned. This review will give an overview of the current evidence for the relationship of LOH and male sexual dysfunction

Association between domains of quality of life and patients with klinefelter syndrome: a systematic review.

Klinefelter syndrome (KS) is the second-most prevalent chromosomal disorder in men, though late diagnosis is very common and 50-75% of men remain undiagnosed. Evidence suggests that men with KS have impaired Quality of Life (QoL) but research on how the diagnosis of KS is associated with different QoL domains and what factors influence patients' QoL is limited. This study aimed to provide a systematic review of the published evidence on factors that influence QoL in men with KS. DESIGN: Systematic review and meta-analysis with narrative synthesis. METHODS: Medline, Cochrane, Embase, Psychinfo, CINAHL, BASE and relevant publication reference lists were searched in January 2021. Eligible studies included RCTs, cohort studies, cross-sectional studies and epidemiology studies on KS and its effect on QoL and all domains of WHOQOL-100. Clinical studies with no date restriction published in English were included. RESULTS: Thematic analysis was completed on thirteen studies, with a meta-analysis of intelligence quotient (IQ) completed on seven studies. Twelve out of 13 studies suggested that KS negatively affected QoL outcomes and KS was associated with impairments in physical, psychological, level independence and social relationship domains of WHOQOL-100. Meta-analysis suggested men with KS have significantly lower full-scale Intelligence Quotient versus controls (P <0.00001). CONCLUSIONS: This is the first evidence synthesis of QoL in men with KS. Current evidence suggests that combined physical and psychological impairments affect men with KS who also experience impairments in relationships and independence in society. Further research is needed to identify factors that influence QoL in men with KS

The role of seminal oxidative stress in recurrent pregnancy loss

Recurrent pregnancy loss is a distressing condition affecting 1-2% of couples. Traditionally investigations have focused on the female, however more recently researchers have started to explore the potential contribution of the male partner. Seminal reactive oxygen species have a physiological function in male reproduction but in excess are suspected to generate structural and functional damage to the sperm. Evidence is mounting to support an association between elevated seminal reaction oxygen species and recurrent pregnancy loss. Studies suggest that the rates of sperm DNA damage are higher in the male partners of women affected by recurrent pregnancy loss compared with unaffected men. However, the available pool of data is conflicting, and interpretation is limited by the recent change in nomenclature and the heterogeneity of study methodologies. Furthermore, investigation into the effects of oxidative stress on the epigenome show promise. The value of antioxidant therapy in the management of recurrent pregnancy loss currently remains unclear

Investigating the role of EphA/ ephrin-A signalling during trigeminal ganglion axon guidance.

The ophthalmic, maxillary and mandibular axon branches of the trigeminal ganglion (TG) provide cutaneous sensory innervation to the vertebrate face, and multiple families of guidance cues amalgamate to direct the navigation of these branches. However, target tissue specific guidance cues that discriminately guide the three TG axon branches are unknown. Prior work demonstrated that EphAs and ephrin-As could discriminately direct dorsal versus ventral motor axon projections into the hindlimb. Similarly, do EphA tyrosine kinases and ephrin-A ligands discriminately guide trigeminal ganglion ophthalmic (TGop) lobe versus maxillomandibular (TGmm) axon projections into the chick embryo face? The aims of this work were two-fold: (1) to identify candidate EphA and ephrin-A molecules during TG axon guidance, and (2) to detennine the functional significance of TG axon EphA and ephrin-A signalling in vitro. This study identified EphA3, EphA4, ephrin-A2 and ephrin-A5 at stages 13, IS and 20, as putative guidance cues to TG axons. TG-EphA3 and -ephrin-A5 were identified as putative receptors to guidance cues expressed in the target fields. EphA3 receptor was differentially expressed, with the TGop lobe expressing higher levels compared to the TGmm lobe. However, ephrin-A5 transcript was not differentially expressed between the two ganglion lobes. In a substratum choice in vitro assay, ephrin-AS-Fc was found to repel approximately 50% of axons growing from stage 20 whole TG explants. This population of axons was identified to be from the TGop lobe. The in vitro data supports the contention that during facial development there may be trigeminal ganglion lobe specific guidance of TGop in comparison to TGmm peripheral sensory axonal projections to target fields coordinated through EphA3 and ephrin-A2/A5 repulsive interactions. In vitro, EphA4-Fc caused morphological changes to TG growth cones, which is likely mediated through TG ephrin-A5 reverse signaling. Furthermore, this study provided in vitro evidence that trigeminal ganglion axons were not responsive to EphA4-Fc, possibly implying that EphAs expressed in the target fields were not repulsive to ganglionic axons during pathfinding. The data suggests that EphN ephrin-A interactions may specifically guide TGop projections into the ophthalmic process similar to lateral motor axon guidance into the hindlimb. For the first time, a model of how EphN ephrin-A interactions and other families of guidance cues may act in concert to guide trigeminal ganglion axons is suggested.Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 200

Investigating the KNDy hypothesis in humans by co-administration of kisspeptin, neurokinin B and naltrexone in men

Context: A subpopulation of hypothalamic neurons co-localise three neuropeptides namely kisspeptin, neurokinin B (NKB) and dynorphin collectively termed KNDy neurons. Animal studies suggest they interact to affect pulsatile GnRH release (KNDy hypothesis); kisspeptin stimulates, NKB modulates and dynorphin (an opioid) inhibits. Objective: To investigate the KNDy hypothesis in humans, we assessed for the first time the effects of co-administration of kisspeptin-54, NKB and an opioid receptor antagonist, naltrexone on LH pulsatility (surrogate marker for GnRH pulsatility) and gonadotropin release. Design, setting and participants: Ethically approved prospective, single-blinded placebo-controlled study. Healthy male volunteers (n=5/group) attended our research facility for 8 study visits. Intervention and main outcome measure: After 1h baseline blood sampling, participants received a different intervention at each visit: oral 50mg naltrexone (NAL), 8h intravenous infusions of vehicle, 2.56nmol/kg/h NKB (NKB), 0.1nmol/kg/h kissspeptin-54 (KP) alone and in combination. Frequent blood sampling to measure plasma gonadotropins and sex steroids was conducted and LH pulsatility was determined using blinded deconvolution analysis. Results: All kisspeptin and naltrexone containing groups potently increased LH and LH pulsatility (p<0.001 vs vehicle). NKB alone did not affect gonadotropins. NKB+KP had significantly lower increases in gonadotropins compared with kisspeptin alone (p<0.01). NAL+KP was the only group to significantly increase LH pulse amplitude (p<0.001 vs vehicle). Conclusions: Our results suggest significant interactions between the KNDy neuropeptides on LH pulsatility and gonadotropin release in humans. This has important implications for improving our understanding of GnRH pulse generation in humans

Understanding and treating ejaculatory dysfunction in men with Diabetes mellitus

INTRODUCTION: Diabetes mellitus (DM) is a rapidly rising metabolic disorder with important systemic complications. Global figures have demonstrated the prevalence of DM has almost quadrupled from 108 million in 1980 to 422 million in 2014, with a current prevalence of over 525 million. Of the male sexual dysfunction resulting from DM, significant focus is afforded to erectile dysfunction (ED). Nevertheless, ejaculatory dysfunction (EjD) constitutes important sexual sequelae in diabetic men, with up to 35-50% of men with DM suffering from EjD. Despite this, aspects of its pathophysiology and treatment are less well understood than ED. The main disorders of ejaculation include premature ejaculation (PE), delayed ejaculation (DE), anejaculation (AE) and retrograde ejaculation (RE). BACKGROUND: Although EjD in DM can have complex multifactorial aetiology, understanding the pathophysiological mechanisms caused by DM has facilitated the development of therapies in the management of EjD. Most of our understanding of its pathophysiology is derived from diabetic animal models, however observational studies in humans have also provided useful information in elucidating important associative factors potentially contributing to EjD in diabetic men. These have provided the potential for more tailored treatment regimens in patients depending on the ejaculatory disorder, other co-existing sequelae of DM, specific metabolic factors as well as the need for fertility treatment. However, the evidence for treatment of EjD, especially DE and RE, is based on low-level evidence comprising small sample-size series and retrospective or cross-sectional studies. Whilst promising findings from large randomised controlled trials (RCTs) have provided strong evidence for the licensed treatment of PE, similar robust studies are needed to accurately elucidate factors predicting EjD in DM, as well as for the development of pharmacotherapies for DE and RE. Similarly, more contemporary robust data is required for fertility outcomes in these patients, including methods of sperm retrieval and assisted reproductive techniques (ART) in RE. This article is protected by copyright. All rights reserved

A systematic review of randomised controlled trials investigating the efficacy and safety of testosterone therapy for female sexual dysfunction in postmenopausal women

The clinical sequelae of oestrogen deficiency during menopause are undoubted. However, the pathophysiological role of testosterone during the menopause is less clear. Several randomised, placebo-controlled clinical trials suggest that testosterone therapy improves sexual function in post-menopausal women. Some studies suggest that testosterone therapy has additional effects which include increased bone mineral density and decreased serum high density lipoprotein (HDL) cholesterol. Furthermore, the long-term safety profile of testosterone therapy in post-menopausal women is not clear. This article will provide a concise and critical summary of the literature, to guide clinicians treating post-menopausal women. This article is protected by copyright. All rights reserved