NOTCH1 signaling establishes the medullary thymic epithelial cell progenitor pool during mouse fetal development.

The cortical and medullary thymic epithelial cell (cTEC and mTEC) lineages are essential for inducing T cell lineage commitment, T cell positive selection and the establishment of self-tolerance, but the mechanisms controlling their fetal specification and differentiation are poorly understood. Here, we show that notch signaling is required to specify and expand the mTEC lineage. Notch1 is expressed by and active in TEC progenitors. Deletion of Notch1 in TECs resulted in depletion of mTEC progenitors and dramatic reductions in mTECs during fetal stages, consistent with defects in mTEC specification and progenitor expansion. Conversely, forced notch signaling in all TECs resulted in widespread expression of mTEC progenitor markers and profound defects in TEC differentiation. In addition, lineage-tracing analysis indicated that all mTECs have a history of receiving a notch signal, consistent with notch signaling occurring in mTEC progenitors. These data provide strong evidence for a requirement for notch signaling in specification of the mTEC lineage.

Bulls fed a high-gain diet decrease blastocyst formation after in vitro fertilization.

In brief: Paternal high-gain diet reduces blastocyst development following in vitro fertilization and embryo culture but does not affect gene expression or cellular allocation of resultant blastocysts. Abstract: Bulls used in cattle production are often overfed to induce rapid growth, early puberty, and increase sale price. While the negative consequences of undernutrition on bull sperm quality are known, it is unclear how a high-gain diet influences embryo development. We hypothesized that semen collected from bulls fed a high-gain diet would have a reduced capacity to produce blastocysts following in vitro fertilization. Eight mature bulls were stratified by body weight and fed the same diet for 67 days at either a maintenance level (0.5% body weight per day; n = 4) or a high-gain rate (1.25% body weight per day; n = 4). Semen was collected by electroejaculation at the end of the feeding regimen and subjected to sperm analysis, frozen, and used for in vitro fertilization. The high-gain diet increased body weight, average daily gain, and subcutaneous fat thickness compared to the maintenance diet. Sperm of high-gain bulls tended to have increased early necrosis and had increased post-thaw acrosome damage compared with maintenance bulls, but diet did not affect sperm motility or morphology. Semen of high-gain bulls reduced the percentage of cleaved oocytes that developed to blastocyst stage embryos. Paternal diet had no effect on the number of total or CDX2-positive cells of blastocysts, or blastocysts gene expression for markers associated with developmental capacity. Feeding bulls a high-gain diet did not affect sperm morphology or motility, but increased adiposity and reduced the ability of sperm to generate blastocyst-stage embryos.

Foot, ankle, and leg problems in Australian primary care: consultation patterns, management practices, and costs.

OBJECTIVE: To explore consultation patterns, management practices, and costs of foot, ankle, and leg problems in Australian primary care. STUDY DESIGN: We analyzed data from the Bettering the Evaluation and Care of Health program, April 2000 to March 2016. Foot, ankle, and leg problems were identified using the International Classification of Primary Care, Version 2 PLUS terminology. Data were summarized using descriptive statistics examining general practitioner (GP) and patient characteristics associated with a foot, ankle, or leg problem being managed. Cost to government was estimated by extracting fees for GP consultations, diagnostic imaging, and pathology services from the Medicare Benefits Schedule (MBS) database. Costs for prescription-only medicines were extracted from the Pharmaceutical Benefits Schedule and for nonprescribed medications, large banner discount pharmacy prices were used. RESULTS: GPs recorded 1,568,100 patient encounters, at which 50,877 foot, ankle, or leg problems were managed at a rate of 3.24 (95% confidence intervals [CIs] 3.21-3.28) per 100 encounters. The management rate of foot, ankle, or leg problems was higher for certain patient characteristics (older, having a health care card, socioeconomically disadvantaged, non-Indigenous, and being English speaking) and GP characteristics (male sex, older age, and Australian graduate). The most frequently used management practice was the use of medications. The average cost (Australian dollars) per encounter was A$52, with the total annual cost estimated at A$256m. CONCLUSIONS: Foot, ankle, and leg problems are frequently managed by GPs, and the costs associated with their management represent a substantial economic impact in Australian primary care.

Encounters and management of oral conditions at general medical practices in Australia.

BACKGROUND: Poor oral health has been widely recognised as an ongoing public health issue. Patients with oral conditions may visit either a general practitioner (GP) or a dental practitioner for management. The aims of this study are to report (i) the GP management rate of oral health conditions by patient and GP demographics, (ii) what specific oral conditions were managed, and (iii) how GPs managed oral conditions. METHODS: Data from the Bettering the Evaluation and Care of Health study (2006 to 2016 inclusive) were analysed. Descriptive statistics with 95% confidence intervals around point estimates were used to summarise data. Multivariate logistic regression was performed to determine the independent effect of patient and GP characteristics. RESULTS: A total of 972,100 GP encounters were included in the dataset, with oral condition-related encounters managed at a rate of 1.19 oral conditions per 100 GP encounters. Patients who were aged 54 years or younger, resided in a socioeconomically disadvantaged area, came from a non-English speaking background or Indigenous background were more likely to have oral conditions managed by GPs. The most commonly reported oral conditions were dental and oral mucosa-related. Over 60% of oral conditions were managed by GPs through prescribed medications. CONCLUSIONS: This study provided an overview of management of oral conditions by GPs in Australia. Patients from certain vulnerable demographic groups were more likely to attend a GP for management of oral conditions. Common oral conditions and management approaches were identified. The findings of this study contribute to public health and health policy discussions around optimising primary care provision in oral health.

Tissue-specific roles for sonic hedgehog signaling in establishing thymus and parathyroid organ fate.

The thymus and parathyroids develop from third pharyngeal pouch (3rd pp) endoderm. Our previous studies show that Shh null mice have smaller, aparathyroid primordia in which thymus fate specification extends into the pharynx. SHH signaling is active in both dorsal pouch endoderm and neighboring neural crest (NC) mesenchyme. It is unclear which target tissue of SHH signaling is required for the patterning defects in Shh mutants. Here, we used a genetic approach to ectopically activate or delete the SHH signal transducer Smo in either pp endoderm or NC mesenchyme. Although no manipulation recapitulated the Shh null phenotype, manipulation of SHH signaling in either the endoderm or NC mesenchyme had direct and indirect effects on both cell types during fate specification and organogenesis. SHH pathway activation throughout pouch endoderm activated ectopic Tbx1 expression and partially suppressed the thymus-specific transcription factor Foxn1, identifying Tbx1 as a key target of SHH signaling in the 3rd pp. However, ectopic SHH signaling was insufficient to expand the GCM2-positive parathyroid domain, indicating that multiple inputs, some of which might be independent of SHH signaling, are required for parathyroid fate specification. These data support a model in which SHH signaling plays both positive and negative roles in patterning and organogenesis of the thymus and parathyroids.

Sympathetic Reinnervation Is Required for Mammalian Cardiac Regeneration.

RATIONALE: Although mammalian cardiac regeneration can occur in the neonatal period, the factors involved in this process remain to be established. Because tissue and limb regeneration require concurrent reinnervation by the peripheral nervous system, we hypothesized that cardiac regeneration also requires reinnervation. OBJECTIVE: To test the hypothesis that reinnervation is required for innate neonatal cardiac regeneration. METHODS AND RESULTS: We crossed a Wnt1-Cre transgenic mouse with a double-tandem Tomato reporter strain to identify neural crest-derived cell lineages including the peripheral autonomic nerves in the heart. This approach facilitated the precise visualization of subepicardial autonomic nerves in the ventricles using whole mount epifluorescence microscopy. After resection of the left ventricular apex in 2-day-old neonatal mice, sympathetic nerve structures, which envelop the heart under normal conditions, exhibited robust regrowth into the regenerating myocardium. Chemical sympathectomy inhibited sympathetic regrowth and subsequent cardiac regeneration after apical resection significantly (scar size as cross-sectional percentage of viable left ventricular myocardium, n=9; 0.87%±1.4% versus n=6; 14.05±4.4%; P<0.01). CONCLUSIONS: These findings demonstrate that the profound regenerative capacity of the neonatal mammalian heart requires sympathetic innervation. As such, these data offer significant insights into an underlying basis for inadequate adult regeneration after myocardial infarction, a situation where nerve growth is hindered by age-related influences and scar tissue.

Assessment and management of asthma and chronic obstructive pulmonary disease in Australian general practice.

BACKGROUND: Dispensing data suggest potential issues with the quality use of medicines for airways disease. OBJECTIVE: The objective of this article was to describe the management of asthma and chronic obstructive pulmonary disease (COPD) in general practice, and investigate the appropriateness of prescribing. METHODS: The method used for this study consisted of a national cross­sectional survey of 91 Australian general practitioners (GPs) participating in the Bettering the Evaluation and Care of Health (BEACH) program. RESULTS: Data were available for 2589 patients (288 asthma; 135 COPD). For the patients with asthma, GPs classified asthma as well controlled in 76.4%; 54.3% were prescribed inhaled corticosteroids (ICS), mostly (84.9%) as combination therapy, and mostly at moderate-high dose; only 26.3% had a written action plan. GPs classified COPD as mild for 42.9%. Most patients with COPD (60.9%) were prescribed combination ICS therapy and 36.7% were prescribed triple therapy. DISCUSSION: There were substantial differences between guideline-based and GP- recorded assessment and prescription for asthma and COPD. Further research is needed to improve care and optimise patient outcomes with scarce health resources.

Fibronectin signals through integrin α5ß1 to regulate cardiovascular development in a cell type-specific manner.

Fibronectin (Fn1) is an evolutionarily conserved extracellular matrix glycoprotein essential for embryonic development. Global deletion of Fn1 leads to mid-gestation lethality from cardiovascular defects. However, severe morphogenetic defects that occur early in embryogenesis in these embryos precluded assigning a direct role for Fn1 in cardiovascular development. We noticed that Fn1 is expressed in strikingly non-uniform patterns during mouse embryogenesis, and that its expression is particularly enriched in the pharyngeal region corresponding with the pharyngeal arches 3, 4, and 6. This region bears a special importance for the developing cardiovascular system, and we hypothesized that the localized enrichment of Fn1 in the pharyngeal region may be essential for cardiovascular morphogenesis. To test this hypothesis, we ablated Fn1 using the Isl1(Cre) knock-in strain of mice. Deletion of Fn1 using the Isl1(Cre) strain resulted in defective formation of the 4th pharyngeal arch arteries (PAAs), aberrant development of the cardiac outflow tract (OFT), and ventricular septum defects. To determine the cell types responding to Fn1 signaling during cardiovascular development, we deleted a major Fn1 receptor, integrin α5 using the Isl1(Cre) strain, and observed the same spectrum of abnormalities seen in the Fn1 conditional mutants. Additional conditional mutagenesis studies designed to ablate integrin α5 in distinct cell types within the Isl1(+) tissues and their derivatives, suggested that the expression of integrin α5 in the pharyngeal arch mesoderm, endothelium, surface ectoderm and the neural crest were not required for PAA formation. Our studies suggest that an (as yet unknown) integrin α5-dependent signal extrinsic to the pharyngeal endothelium mediates the formation of the 4th PAAs.

Estimating non-billable time in Australian general practice.

OBJECTIVES: To quantify the time that general practitioners spend on patient care that is not claimable from Medicare (non-billable) and the monetary value of this work were it claimable, and to identify variables independently associated with non-billable time. DESIGN: Prospective, cross-sectional survey, April 2012 - March 2014. SETTING: Australian general practice; a substudy of the national Bettering the Evaluation and Care of Health (BEACH) program. PARTICIPANTS: 1935 randomly sampled GPs (77.4% participation rate) from across Australia provided filled questionnaires on 66 458 patient encounters. MAIN OUTCOME MEASURES: Non-billable time spent on patient care since patient's previous consultation; duration of and reasons for non-billable time; estimate of its monetary value were it claimable from Medicare; variables associated with non-billable time. RESULTS: 69.5% of GPs reported non-billable care outside patient visits; 8019 patient encounters (12.1%) were associated with an occasion of non-billable time. Mean time spent per occasion was 10.1 min (range, 1-240 min). Reasons for non-billable time included arranging tests and referrals, consulting specialists or allied health professionals, medication renewals, and advice and education, and encompassed all International Classification of Primary Care Version 2 chapters. The notional average annual value per GP of this work was $10 525.95 (level A rebate) to $23 008.05 (level B). Non-billable time was independently associated with female GPs, younger GPs (under 55 years), female patients, patients aged 65 years or more, and one or more chronic problems being managed at the recorded encounter. CONCLUSION: Most GPs spend a significant amount of unpaid time on patient care between consultations, an inherent problem of the fee-for-service system. This work should inform discussions of future funding models.

Rab23 regulates Nodal signaling in vertebrate left-right patterning independently of the Hedgehog pathway.

Asymmetric fluid flow in the node and Nodal signaling in the left lateral plate mesoderm (LPM) drive left-right patterning of the mammalian body plan. However, the mechanisms linking fluid flow to asymmetric gene expression in the LPM remain unclear. Here we show that the small GTPase Rab23, known for its role in Hedgehog signaling, plays a separate role in Nodal signaling and left-right patterning in the mouse embryo. Rab23 is not required for initial symmetry breaking in the node, but it is required for expression of Nodal and Nodal target genes in the LPM. Microinjection of Nodal protein and transfection of Nodal cDNA in the embryo indicate that Rab23 is required for the production of functional Nodal signals, rather than the response to them. Using gain- and loss-of function approaches, we show that Rab23 plays a similar role in zebrafish, where it is required in the teleost equivalent of the mouse node, Kupffer׳s vesicle. Collectively, these data suggest that Rab23 is an essential component of the mechanism that transmits asymmetric patterning information from the node to the LPM.

Localised inhibition of FGF signalling in the third pharyngeal pouch is required for normal thymus and parathyroid organogenesis.

The thymus and parathyroid glands are derived from the third pharyngeal pouch endoderm. The mechanisms that establish distinct molecular domains in the third pouch and control the subsequent separation of these organ primordia from the pharynx are poorly understood. Here, we report that mouse embryos that lack two FGF feedback antagonists, Spry1 and Spry2, display parathyroid and thymus hypoplasia and a failure of these organ primordia to completely separate from the pharynx. We show that FGF ligands and downstream reporter genes are expressed in highly regionalised patterns in the third pouch and that sprouty gene deletion results in upregulated FGF signalling throughout the pouch endoderm. As a consequence, the initiation of markers of parathyroid and thymus fate is altered. In addition, a normal apoptotic programme that is associated with the separation of the primordia from the pharynx is disrupted, resulting in the maintenance of a thymus-pharynx attachment and a subsequent inability of the thymus to migrate to its appropriate position above the heart. We demonstrate that the sprouty genes function in the pharyngeal endoderm itself to control these processes and that the defects in sprouty-deficient mutants are, at least in part, due to hyper-responsiveness to Fgf8. Finally, we provide evidence to suggest that parathyroid hypoplasia in these mutants is due to early gene expression defects in the third pouch, whereas thymus hypoplasia is caused by reduced proliferation of thymic epithelial cells in the thymus primordium.

Ordering chest X-rays in Australian general practice.

Data from the BEACH program between 2012­14 were used to examine general practice encounters where chest X-rays were ordered. This included the most common problems associated with chest X-ray ordering and patient characteristics. Changes in ordering between 2004­05 and 2013­14 were also investigated. The rate of chest X-ray ordering between 2004­05 and 2013­14 decreased significantly. In 2012­14, chest X-rays were most often ordered in the management of acute bronchitis/bronchiolitis, cough and pneumonia. Pleurisy/pleural effusion had the highest likelihood of resulting in a chest X-ray order, followed by shortness of breath/dyspnoea and pneumonia.

The management of unresolved gastrointestinal symptoms in Australian general practice.

BEACH data collected in 2012-14 were used to investigate the management of unresolved gastrointestinal (GI) symptoms in Australian general practice. This included the characteristics of patients who had unresolved GI symptoms managed, and a comparison with the management of new GI symptoms. Nearly half of the GI symptoms managed in 2012-14 were unresolved (had been managed previously). The findings suggest that general practitioners order pathology and imaging tests more often during first presentations of GI symptoms, and often refer patients when GI symptoms are unresolved.

Mechanisms of thymus organogenesis and morphogenesis.

The thymus is the primary organ responsible for generating functional T cells in vertebrates. Although T cell differentiation within the thymus has been an area of intense investigation, the study of thymus organogenesis has made slower progress. The past decade, however, has seen a renewed interest in thymus organogenesis, with the aim of understanding how the thymus develops to form a microenvironment that supports T cell maturation and regeneration. This has prompted modern revisits to classical experiments and has driven additional genetic approaches in mice. These studies are making significant progress in identifying the molecular and cellular mechanisms that control specification, early organogenesis and morphogenesis of the thymus.

Technology in practice ­ GP computer use by age.

Since 2005, more than 95% of general practitioners (GPs) have had access to computers in their clinical work. We have analysed the most recent 2 years of BEACH data (April 2012-March 2014) to determine whether GP age affects clinical computer use.

Assessing Decision Fatigue in General Practitioners' Prescribing Decisions Using the Australian BEACH Data Set.

BACKGROUND: General practitioners (GPs) make numerous care decisions throughout their workdays. Extended periods of decision making can result in decision fatigue, a gradual shift toward decisions that are less cognitively effortful. This study examines whether observed patterns in GPs' prescribing decisions are consistent with the decision fatigue phenomenon. We hypothesized that the likelihood of prescribing frequently overprescribed medications (antibiotics, benzodiazepines, opioids; less effortful to prescribe) will increase and the likelihood of prescribing frequently underprescribed medications (statins, osteoporosis medications; more effortful to prescribe) will decrease over the workday. METHODS: This study used nationally representative primary care data on GP-patient encounters from the Bettering the Evaluation and Care of Health program from Australia. The association between prescribing decisions and order of patient encounters over a GP's workday was assessed with generalized linear mixed models accounting for clustering and adjusting for patient, provider, and encounter characteristics. RESULTS: Among 262,456 encounters recorded by 2,909 GPs, the odds of prescribing antibiotics significantly increased by 8.7% with 15 additional patient encounters (odds ratio [OR] = 1.087; confidence interval [CI] = 1.059-1.116). The odds of prescribing decreased significantly with 15 additional patient encounters by 6.3% for benzodiazepines (OR = 0.937; CI = 0.893-0.983), 21.9% for statins (OR = 0.791; CI = 0.753-0.831), and 25.0% for osteoporosis medications (OR = 0.750; CI = 0.690-0.814). No significant effects were observed for opioids. All findings were replicated in confirmatory analyses except the effect of benzodiazepines. CONCLUSIONS: GPs were increasingly likely to prescribe antibiotics and were less likely to prescribe statins and osteoporosis medications as the workday wore on, which was consistent with decision fatigue. There was no convincing evidence of decision fatigue effects in the prescribing of opioids or benzodiazepines. These findings establish decision fatigue as a promising target for optimizing prescribing behavior. HIGHLIGHTS: We found that as general practitioners progress through their workday, they become more likely to prescribe antibiotics that are reportedly overprescribed and less likely to prescribe statins and osteoporosis medications that are reportedly underprescribed.This change in decision making over time is consistent with the decision fatigue phenomenon. Decision fatigue occurs when we make many decisions without taking a rest break. As we make those decisions, we become gradually more likely to make decisions that are less difficult.The findings of this study show that decision fatigue is a possible target for improving guideline-compliant prescribing of pharmacologic medications.

EphB-ephrin-B2 interactions are required for thymus migration during organogenesis.

Thymus organogenesis requires coordinated interactions of multiple cell types, including neural crest (NC) cells, to orchestrate the formation, separation, and subsequent migration of the developing thymus from the third pharyngeal pouch to the thoracic cavity. The molecular mechanisms driving these processes are unclear; however, NC-derived mesenchyme has been shown to play an important role. Here, we show that, in the absence of ephrin-B2 expression on thymic NC-derived mesenchyme, the thymus remains in the cervical area instead of migrating into the thoracic cavity. Analysis of individual NC-derived thymic mesenchymal cells shows that, in the absence of ephrin-B2, their motility is impaired as a result of defective EphB receptor signaling. This implies a NC-derived cell-specific role of EphB-ephrin-B2 interactions in the collective migration of the thymic rudiment during organogenesis.

Under or over? General practitioner charging of Medicare.

BACKGROUND AND OBJECTIVES: In 2022, media reports alleged that doctors, particularly general practitioners (GPs), are defrauding Medicare, claiming $8 billion lost through fraud/non-compliance. This study examined Medicare Benefits Schedule billing patterns by consultation length to estimate overcharging or undercharging by GPs, and the cost/savings to Medicare. METHOD: A subset of data from the Bettering the Evaluation And Care of Health (BEACH) program from 2013 to 2016, which included length of consultation information, was analysed. RESULTS: Of 89,765 consultations, GPs undercharged 11.8% of consultations and overcharged 1.6%. Of the 2760 GPs sampled, 816 (29.6%) overcharged at least once and 2334 (84.6%) undercharged at least once. Of the GPs who overcharged at least once, 85.4% also undercharged. The total effect of GP undercharging and overcharging was a net saving of $351.7 million to Medicare. DISCUSSION: This study shows that GPs undercharging and overcharging saved Medicare over one-third of a billion dollars in 2021-22. The findings of this study do not support the media claims of widespread fraud by GPs.

A call to action for more disability-inclusive health policy and systems research.

To date, the exclusion of people with disability participating in research has limited the evidence base informing health system strengthening policy and practice more generally, and addressing disability-related inequalities in access to health services and better health outcomes more particularly. Given that more than 1 billion people, or 16% of the world's population, have a disability, we may fail to respond to the needs of a large proportion of the population unless we are purposeful with inclusion. Our research in this area indicates that online qualitative methods can be effective in engaging under-represented groups and are essential to ensure their input into health policy and systems research. This has important implications for researchers whose responsibility it is to make all health research disability inclusive, for ethical and methodological reasons, so they do not perpetuate the under-representation of people with disability in health policy and systems research. Our paper puts forward several recommendations to facilitate more people with disability participating in health policy and systems research. By critically reflecting on a health system strengthening research project, in which we purposefully aimed to support the participation of people with disability, we identify lessons learnt and issues to consider when planning and conducting accessible research. We also propose a set of actions for moving the agenda forward.