The anatomy of the head muscles in caecilians (Amphibia: Gymnophiona): Variation in relation to phylogeny and ecology?

In limbless fossorial vertebrates such as caecilians (Gymnophiona), head-first burrowing imposes severe constraints on the morphology and overall size of the head. As such, caecilians developed a unique jaw-closing system involving the large and well-developed m. interhyoideus posterior, which is positioned in such a way that it does not significantly increase head diameter. Caecilians also possess unique muscles among amphibians. Understanding the diversity in the architecture and size of the cranial muscles may provide insights into how a typical amphibian system was adapted for a head-first burrowing lifestyle. In this study, we use dissection and non-destructive contrast-enhanced micro-computed tomography (µCT) scanning to describe and compare the cranial musculature of 13 species of caecilians. Our results show that the general organization of the head musculature is rather constant across extant caecilians. However, the early-diverging Rhinatrema bivittatum mainly relies on the 'ancestral' amphibian jaw-closing mechanism dominated by the m. adductores mandibulae, whereas other caecilians switched to the use of the derived dual jaw-closing mechanism involving the additional recruitment of the m. interhyoideus posterior. Additionally, the aquatic Typhlonectes show a greater investment in hyoid musculature than terrestrial caecilians, which is likely related to greater demands for ventilating their large lungs, and perhaps also an increased use of suction feeding. In addition to three-dimensional interactive models, our study provides the required quantitative data to permit the generation of accurate biomechanical models allowing the testing of further functional hypotheses.

Is vertebral shape variability in caecilians (Amphibia: Gymnophiona) constrained by forces experienced during burrowing?

Caecilians are predominantly burrowing, elongate, limbless amphibians that have been relatively poorly studied. Although it has been suggested that the sturdy and compact skulls of caecilians are an adaptation to their head-first burrowing habits, no clear relationship between skull shape and burrowing performance appears to exist. However, the external forces encountered during burrowing are transmitted by the skull to the vertebral column, and, as such, may impact vertebral shape. Additionally, the muscles that generate the burrowing forces attach onto the vertebral column and consequently may impact vertebral shape that way as well. Here, we explored the relationships between vertebral shape and maximal in vivo push forces in 13 species of caecilian amphibians. Our results show that the shape of the two most anterior vertebrae, as well as the shape of the vertebrae at 90% of the total body length, is not correlated with peak push forces. Conversely, the shape of the third vertebrae, and the vertebrae at 20% and 60% of the total body length, does show a relationship to push forces measured in vivo. Whether these relationships are indirect (external forces constraining shape variation) or direct (muscle forces constraining shape variation) remains unclear and will require quantitative studies of the axial musculature. Importantly, our data suggest that mid-body vertebrae may potentially be used as proxies to infer burrowing capacity in fossil representatives.

Regional differences in vertebral shape along the axial skeleton in caecilians (Amphibia: Gymnophiona).

Caecilians are elongate, limbless and annulated amphibians that, as far as is known, all have an at least partly fossorial lifestyle. It has been suggested that elongate limbless vertebrates show little morphological differentiation throughout the postcranial skeleton. However, relatively few studies have explored the axial skeleton in limbless tetrapods. In this study, we used µCT data and three-dimensional geometric morphometrics to explore regional differences in vertebral shape across a broad range of caecilian species. Our results highlight substantial differences in vertebral shape along the axial skeleton, with anterior vertebrae being short and bulky, whereas posterior vertebrae are more elongated. This study shows that despite being limbless, elongate tetrapods such as caecilians still show regional heterogeneity in the shape of individual vertebrae along the vertebral column. Further studies are needed, however, to understand the possible causes and functional consequences of the observed variation in vertebral shape in caecilians.

The relationship between head shape, head musculature and bite force in caecilians (Amphibia: Gymnophiona).

Caecilians are enigmatic limbless amphibians that, with a few exceptions, all have an at least partly burrowing lifestyle. Although it has been suggested that caecilian evolution resulted in sturdy and compact skulls as an adaptation to their head-first burrowing habits, no relationship between skull shape and burrowing performance has been demonstrated to date. However, the unique dual jaw-closing mechanism and the osteological variability of their temporal region suggest a potential relationship between skull shape and feeding mechanics. Here, we explored the relationships between skull shape, head musculature and in vivo bite forces. Although there is a correlation between bite force and external head shape, no relationship between bite force and skull shape could be detected. Whereas our data suggest that muscles are the principal drivers of variation in bite force, the shape of the skull is constrained by factors other than demands for bite force generation. However, a strong covariation between the cranium and mandible exists. Moreover, both cranium and mandible shape covary with jaw muscle architecture. Caecilians show a gradient between species with a long retroarticular process associated with a large and pennate-fibered m. interhyoideus posterior and species with a short process but long and parallel-fibered jaw adductors. Our results demonstrate the complexity of the relationship between form and function of this jaw system. Further studies that focus on factors such as gape distance or jaw velocity will be needed in order to fully understand the evolution of feeding mechanics in caecilians.

Under pressure: the relationship between cranial shape and burrowing force in caecilians (Gymnophiona).

Caecilians are elongate, limbless and annulated amphibians that, with the exception of one aquatic family, all have an at least partly fossorial lifestyle. It has been suggested that caecilian evolution resulted in sturdy and compact skulls with fused bones and tight sutures, as an adaptation to their head-first burrowing habits. However, although their cranial osteology is well described, relationships between form and function remain poorly understood. In the present study, we explored the relationship between cranial shape and in vivo burrowing forces. Using micro-computed tomography (µCT) data, we performed 3D geometric morphometrics to explore whether cranial and mandibular shapes reflected patterns that might be associated with maximal push forces. The results highlight important differences in maximal push forces, with the aquatic Typhlonectes producing a lower force for a given size compared with other species. Despite substantial differences in head morphology across species, no relationship between overall skull shape and push force could be detected. Although a strong phylogenetic signal may partly obscure the results, our conclusions confirm previous studies using biomechanical models and suggest that differences in the degree of fossoriality do not appear to be driving the evolution of head shape.

Biomarker profiling for risk of future heart failure (HFpEF) development.

BACKGROUND: The purpose of this study was to investigate the utility of BNP, hsTroponin-I, interleukin-6, sST2, and galectin-3 in predicting the future development of new onset heart failure with preserved ejection fraction (HFpEF) in asymptomatic patients at-risk for HF. METHODS: This is a retrospective analysis of the longitudinal STOP-HF study of thirty patients who developed HFpEF matched to a cohort that did not develop HFpEF (n = 60) over a similar time period. Biomarker candidates were quantified at two time points prior to initial HFpEF diagnosis. RESULTS: HsTroponin-I and BNP at baseline and follow-up were statistically significant predictors of future new onset HFpEF, as was galectin-3 at follow-up and concentration change over time. Interleukin-6 and sST2 were not predictive of future development of new onset HFpEF in this study. Unadjusted biomarker combinations of hsTroponin-I, BNP, and galectin-3 could significantly predict future HFpEF using both baseline (AUC 0.82 [0.73,0.92]) and follow-up data (AUC 0.86 [0.79,0.94]). A relative-risk matrix was developed to categorize the relative-risk of new onset of HFpEF based on biomarker threshold levels. CONCLUSION: We provided evidence for the utility of BNP, hsTroponin-I, and Galectin-3 in the prediction of future HFpEF in asymptomatic event-free populations with cardiovascular disease risk factors.

Tetranectin, a potential novel diagnostic biomarker of heart failure, is expressed within the myocardium and associates with cardiac fibrosis.

Heart failure (HF) screening strategies require biomarkers to predict disease manifestation to aid HF surveillance and management programmes. The aim of this study was to validate a previous proteomics discovery programme that identified Tetranectin as a potential HF biomarker candidate based on expression level changes in asymptomatic patients at future risk for HF development. The initial study consisted of 132 patients, comprising of HF (n = 40), no-HF controls (n = 60), and cardiac surgery patients (n = 32). Serum samples were quantified for circulating levels of Tetranectin and a panel of circulating fibro-inflammatory markers. Cardiac tissue served as a resource to investigate the relationship between cardiac Tetranectin levels and fibrosis and inflammation within the myocardium. An independent cohort of 224 patients with or without HF was used to validate serum Tetranectin levels. Results show that circulating Tetranectin levels are significantly reduced in HF patients (p < 0.0001), and are associated with HF more closely than B-type natriuretic peptide (AUC = 0.97 versus 0.84, p = 0.011). Serum Tetranectin negatively correlated with circulating fibrosis markers, whereas cardiac tissue Tetranectin correlated positively with fibrotic genes and protein within the myocardium. In conclusion, we report for the first time that Tetranectin is a promising HF biomarker candidate linked with fibrotic processes within the myocardium.

Influence of diabetes on natriuretic peptide thresholds in screening for Stage B heart failure.

CONTEXT: Natriuretic peptide (NP) has been shown to be an effective screening tool to identify patients with Stage B heart failure and to have clinical value in preventing heart failure progression. The impact of associated metabolic confounders on the screening utility of NP needs clarification. OBJECTIVE: To assess the impact of diabetes mellitus (DM) on NP screening for asymptomatic Stage B heart failure. MATERIALS AND METHODS: The study population consisted of 1368 asymptomatic patients with cardiovascular risk factors recruited from general practice as part of the STOP-HF trial. B-type NP (BNP) was quantified at point-of-care. RESULTS: BNP was found to be as accurate for detecting Stage B heart failure in DM patients compared to non-DM patients (AUC 0.75 [0.71,0.78] and 0.77 [0.72,0.82], respectively). However, different BNP thresholds are required to achieve the same level of diagnostic sensitivity in DM compared with non-DM patients. To achieve 80% sensitivity a difference of 5-ng/L lower is required for patients with DM. CONCLUSION: Although a significantly different BNP threshold is detected for patients with DM, the BNP concentration difference is small and unlikely to warrant a clinically different diagnostic threshold.

Decreased maternal hypothalamic-pituitary-adrenal axis activity in very severely obese pregnancy: Associations with birthweight and gestation at delivery.

BACKGROUND: The maternal hypothalamic-pituitary-adrenal-axis (HPAA) undergoes dramatic activation during pregnancy. Increased cortisol and corticotrophin-releasing-hormone (CRH) associate with low birthweight and preterm labor. In non-pregnant obesity, the HPAA is activated but circulating cortisol levels are normal or lower than in lean women. We hypothesized that maternal cortisol levels would be lower in obese pregnancy, and would associate with increased fetal size and length of gestation. METHOD: Fasting serum cortisol was measured at 16, 28 and 36 weeks gestation and at 3-6 months postpartum in 276 severely obese and 135 lean women. In a subset of obese (n=20) and lean (n=20) we measured CRH, hormones that regulate bioavailable cortisol (corticosteroid-binding-globulin, estradiol, estriol, and progesterone). Urinary glucocorticoid metabolites were measured in pregnant (obese n=6, lean n=5) and non-pregnant (obese n=7, lean n=7) subjects. RESULTS: Maternal cortisol and HPAA hormones were lower in obese pregnancy. Total urinary glucocorticoid metabolites increased significantly in lean pregnancy, but not in obese. Lower maternal cortisol in obese tended to be associated with increased birthweight (r=-0.13, p=0.066). In obese, CRH at 28 weeks correlated inversely with gestational length (r=-0.49, p=0.04), and independently predicted gestational length after adjustment for confounding factors (mean decrease in CRH of -0.25 pmol/L (95% CI -0.45 to -0.043 pmol/L) per/day increase in gestation). CONCLUSION: In obese pregnancy, lower maternal cortisol without an increase in urinary glucocorticoid clearance may indicate a lesser activation of the HPAA than in lean pregnancy. This may offer a novel mechanism underlying increased birthweight and longer gestation in obese pregnancy.

In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri.

In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology.

Associations between maternal level of education and occupational status with placental glucocorticoid regeneration and sensitivity.

OBJECTIVES: Low socio-economic status (SES) is associated with increased disease risk in the involved and the next generation. The effects of low maternal SES on the offspring may be initiated prenatally. We hypothesized that fetoplacental glucocorticoid exposure might mediate the links. We examined associations between maternal level of education and occupational status (used as indices of SES) and placental expression of genes involved in glucocorticoid exposure and transfer between the mother and foetus. DESIGN AND PATIENTS: Placental biopsies were obtained from 67 healthy women (age 32.2 ± 5.3 years) with singleton, term pregnancies without obstetric complications who participated in a prospective Prediction and Prevention of Preeclampsia (PREDO) study. MEASURES: Level of education was self-reported, and occupational status was extracted from hospital records. Relative glucocorticoid receptor (GR; NR3C1), mineralocorticoid receptor (MR; NR3C2) and 11-beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) and 2 (HSD11B2) mRNA levels were quantified by real-time PCR. RESULTS: Placental GR and HSD11B1 expression increased with decreasing maternal education (unadjusted P-values for linear trend = 0.04 and 0.02 and adjusted P-values = 0.06 and 0.09, respectively). Mothers with primary/secondary education had 52.9% (95% CI, 6.2-99.6, P = 0.03, adjusted P = 0.05) and 79.6% (95% CI, 6.5-153.6, P = 0.03, adjusted P = 0.09) higher GR and HSD11B1 mRNA levels compared with mothers with tertiary education. There were no other significant associations. CONCLUSIONS: Lower maternal level of education is associated with increased placental GR and HSD11B1 gene expression. This combination may regenerate active glucocorticoids in placenta and increase placental sensitivity to glucocorticoids, potentially leading to greater placental and foetal glucocorticoid exposure.

Conflicts of interest in approvals of additives to food determined to be generally recognized as safe: out of balance.

IMPORTANCE: Food and Drug Administration (FDA) guidance allows food manufacturers to determine whether additives to food are "generally recognized as safe" (GRAS). Manufacturers are not required to notify the FDA of a GRAS determination, although in some instances they notify the agency. The individuals that companies select to make these determinations may have financial conflicts of interest. OBJECTIVE: To determine the extent to which individuals selected by manufacturers to make GRAS determinations have conflicts of interest between their obligations to ensure that the use of the additive is safe and their financial relationships to the company. DESIGN Using conflict of interest criteria developed by a committee of the Institute of Medicine, we analyzed 451 GRAS notifications that were voluntarily submitted to the FDA between 1997 and 2012. MAIN OUTCOMES AND MEASURES: Number of GRAS notices submitted to the FDA; frequency of various types of relationships between decision maker and additive manufacturer; frequency of participation on GRAS panels by individuals; and number of GRAS safety determinations identified by the FDA that were not submitted to the agency. RESULTS: For the 451 GRAS notifications, 22.4% of the safety assessments were made by an employee of an additive manufacturer, 13.3% by an employee of a consulting firm selected by the manufacturer, and 64.3% by an expert panel selected by either a consulting firm or the manufacturer. A standing expert panel selected by a third party made none of these safety assessments. The 290 panels that made GRAS determinations had an average of 3.5 members, with a maximum of 7. Ten individuals served on 27 or more panels; 1 individual served on 128 panels (44.1%). At least 1 of the 10 individuals with the most frequent service was a member of 225 panels (77.6%). CONCLUSIONS AND RELEVANCE: Between 1997 and 2012, financial conflicts of interest were ubiquitous in determinations that an additive to food was GRAS. The lack of independent review in GRAS determinations raises concerns about the integrity of the process and whether it ensures the safety of the food supply, particularly in instances where the manufacturer does not notify the FDA of the determination. The FDA should address these concerns.

The risk of maternal obesity to the long-term health of the offspring.

The prevalence of maternal obesity has risen dramatically in recent years, with approximately one in five pregnant women in the UK now classed as obese (body mass index ≥ 30 kg/m(2) ) at antenatal booking. Obesity during pregnancy has been hypothesized to exert long-term health effects on the developing child through 'early life programming'. While this phenomenon has been well studied in a maternal undernutrition paradigm, the processes by which the programming effects of maternal obesity are mediated are less well understood. In humans, maternal obesity has been associated with a number of long-term adverse health outcomes in the offspring, including lifelong risk of obesity and metabolic dysregulation with increased insulin resistance, hypertension and dyslipidaemia, as well as behavioural problems and risk of asthma. The complex relationships between the maternal metabolic milieu and the developing foetus, as well as the potential influence of postnatal lifestyle and environment, have complicated efforts to study the programming effects of maternal overnutrition in humans. This review will examine the emerging evidence from human studies linking maternal obesity to adverse offspring outcomes.

US Food and Drug Administration Regulation of Medical Devices and Radiation Oncology: Can Reform Improve Safety?

Although radiation therapy is highly safe and effective in treating cancer, recent reports of dangerous radiation-related errors have focused a national spotlight on the field of radiation oncology and, more specifically, on the rapidly evolving and complex nature of radiation devices and how they are regulated. The purpose of this review is to explore the issues involved in medical device regulation in radiation oncology. We start with a general review of federal medical device regulation, including explanations of the legal and regulatory framework, and then discuss issues specific to radiation oncology with real-world examples. We also provide our thoughts on potential solutions and reforms to the current system, including better reporting of radiation-related errors in a centralized database, well-defined criteria for establishing substantial equivalence of a new device, and standard postmarket surveillance of radiation devices. Modern radiation therapy is a powerful tool that can help cure many patients' cancers and alleviate others' suffering with limited adverse effects. We must ensure that this promise is never compromised by avoidable mistakes.

FDA regulation of tobacco: blessing or curse for FDA professionals?

Upwards of 400,000 Americans will die that year from the effects of cigarettes, which FDA will now "regulate" very gently, with its hands tied by a slick statutory protection for the largest existing tobacco marketers. Career FDA professionals will be criticized as enablers of mega-marketers' continued sales, working at the margins, arranging the paperwork for protection of megafirms' market share, and sitting by as the deaths and addictive behaviors continue. "Join the Public Health Service, inspired by a public health mission," they were told, and yet they will be unable to do much regulating of the addictive and fatal products for which they now have titular responsibility. This essay observes that these fine FDA professionals are handed the sticky remains of a messy bargain, negotiated in a distracted Congress by expensive lawyers with clients who were potent contributors to political action committees. The only formula that is not secret about the 2009 law is the way in which industry purchased sufficient allegiance to gather the votes for its adoption. The remaining mystery is how FDA could be expected to do these tasks without losing its best and brightest professionals to other fields.

The role of common viral ocular pathogens in Thygeson's superficial punctate keratitis.

BACKGROUND/AIMS: The aetiology of Thygeson's superficial punctate keratitis (TSPK) remains elusive. A viral aetiology has been suggested by the absence of bacterial infection and clinical resemblance to other viral keratopathies. We report the results of polymerase chain reaction analysis for the detection of herpes simplex virus (HSV) 1 and 2, herpes zoster virus, varicella zoster virus (VZV) and adenovirus from corneal epithelial samples from patients with active signs and symptoms of TSPK. METHODS: Schirmer strip impressions were taken from the epithelium of eight patients with a known history of TSPK and symptoms and signs of active disease. Three patients were recruited as positive controls (two with herpes simplex keratitis and one with herpes zoster ophthalmicus). Samples from a further three patients acted as negative controls. All 14 samples underwent polymerase chain reaction testing for HSV 1, HSV 2, VZV and adenovirus. RESULTS: DNA corresponding to the expected viral DNA was amplified from all three positive control samples. The three negative control samples showed no evidence of viral DNA. Similarly, all samples from patients with TSPK showed no evidence of the presence of HSV 1, HSV 2, VZV or adenovirus. CONCLUSION: We conclude that HSV, VZV and adenovirus are not present in the epithelium of patients with TSPK. These results are considered in light of existing theories regarding the aetiology and treatment of this condition.

Extremely high-power tongue projection in plethodontid salamanders.

Many plethodontid salamanders project their tongues ballistically at high speed and for relatively great distances. Capturing evasive prey relies on the tongue reaching the target in minimum time, therefore it is expected that power production, or the rate of energy release, is maximized during tongue launch. We examined the dynamics of tongue projection in three genera of plethodontids (Bolitoglossa, Hydromantes and Eurycea), representing three independent evolutionary transitions to ballistic tongue projection, by using a combination of high speed imaging, kinematic and inverse dynamics analyses and electromyographic recordings from the tongue projector muscle. All three taxa require high-power output of the paired tongue projector muscles to produce the observed kinematics. Required power output peaks in Bolitoglossa at values that exceed the greatest maximum instantaneous power output of vertebrate muscle that has been reported by more than an order of magnitude. The high-power requirements are likely produced through the elastic storage and recovery of muscular kinetic energy. Tongue projector muscle activity precedes the departure of the tongue from the mouth by an average of 117 ms in Bolitoglossa, sufficient time to load the collagenous aponeuroses within the projector muscle with potential energy that is subsequently released at a faster rate during tongue launch.