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Recombination increases the local GC-content in genomic regions through GC-biased gene conversion (gBGC). The recent discovery of a large genomic region with extreme GC-content in the fat sand rat Psammomys obesus provides a model to study the effects of gBGC on chromosome evolution. Here, we compare the GC-content and GC-to-AT substitution patterns across protein-coding genes of four gerbil species and two murine rodents (mouse and rat). We find that the known high-GC region is present in all the gerbils, and is characterized by high substitution rates for all mutational categories (AT-to-GC, GC-to-AT, and GC-conservative) both at synonymous and nonsynonymous sites. A higher AT-to-GC than GC-to-AT rate is consistent with the high GC-content. Additionally, we find more than 300 genes outside the known region with outlying values of AT-to-GC synonymous substitution rates in gerbils. Of these, over 30% are organized into at least 17 large clusters observable at the megabase-scale. The unusual GC-skewed substitution pattern suggests the evolution of genomic regions with very high recombination rates in the gerbil lineage, which can lead to a runaway increase in GC-content. Our results imply that rapid evolution of GC-content is possible in mammals, with gerbil species providing a powerful model to study the mechanisms of gBGC., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

The sand rat Psammomys obesus is a gerbil species native to deserts of North Africa and the Middle East, and is constrained in its ecology because high carbohydrate diets induce obesity and type II diabetes that, in extreme cases, can lead to pancreatic failure and death. We report the sequencing of the sand rat genome and discovery of an unusual, extensive, and mutationally biased GC-rich genomic domain. This highly divergent genomic region encompasses several functionally essential genes, and spans the ParaHox cluster which includes the insulin-regulating homeobox gene Pdx1. The sequence of sand rat Pdx1 has been grossly affected by GC-biased mutation, leading to the highest divergence observed for this gene across the Bilateria. In addition to genomic insights into restricted caloric intake in a desert species, the discovery of a localized chromosomal region subject to elevated mutation suggests that mutational heterogeneity within genomes could influence the course of evolution., Competing Interests: Conflict of interest statement: J.C., P.G.J., M.T.H., S.V.H.P., S.B., K.S., B.A.F., and R.S.H. are current or former employees of Novo Nordisk.

Portable DNA sequencers such as the Oxford Nanopore MinION device have the potential to be truly disruptive technologies, facilitating new approaches and analyses and, in some cases, taking sequencing out of the lab and into the field. However, the capabilities of these technologies are still being revealed. Here we show that single-molecule cDNA sequencing using the MinION accurately characterises venom toxin-encoding genes in the painted saw-scaled viper, Echis coloratus. We find the raw sequencing error rate to be around 12%, improved to 0-2% with hybrid error correction and 3% with de novo error correction. Our corrected data provides full coding sequences and 5' and 3' UTRs for 29 of 33 candidate venom toxins detected, far superior to Illumina data (13/40 complete) and Sanger-based ESTs (15/29). We suggest that, should the current pace of improvement continue, the MinION will become the default approach for cDNA sequencing in a variety of species.

The identification of apparently conserved gene complements in the venom and salivary glands of a diverse set of reptiles led to the development of the Toxicofera hypothesis - the single, early evolution of the venom system in reptiles. However, this hypothesis is based largely on relatively small scale EST-based studies of only venom or salivary glands and toxic effects have been assigned to only some putative Toxicoferan toxins in some species. We set out to examine the distribution of these proposed venom toxin transcripts in order to investigate to what extent conservation of gene complements may reflect a bias in previous sampling efforts. Our quantitative transcriptomic analyses of venom and salivary glands and other body tissues in five species of reptile, together with the use of available RNA-Seq datasets for additional species, shows that the majority of genes used to support the establishment and expansion of the Toxicofera are in fact expressed in multiple body tissues and most likely represent general maintenance or "housekeeping" genes. The apparent conservation of gene complements across the Toxicofera therefore reflects an artefact of incomplete tissue sampling. We therefore conclude that venom has evolved multiple times in reptiles., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Understanding the evolution of the vertebrate pancreas is key to understanding its functions. The chondrichthyes (cartilaginous fish such as sharks and rays) have often been suggested to possess the most ancient example of a distinct pancreas with both hormonal (endocrine) and digestive (exocrine) roles. The lack of genetic, genomic and transcriptomic data for cartilaginous fish has hindered a more thorough understanding of the molecular-level functions of the chondrichthyan pancreas, particularly with respect to their "unusual" energy metabolism (where ketone bodies and amino acids are the main oxidative fuel source) and their paradoxical ability to both maintain stable blood glucose levels and tolerate extensive periods of hypoglycemia. In order to shed light on some of these processes, we carried out the first large-scale comparative transcriptomic survey of multiple cartilaginous fish tissues: the pancreas, brain and liver of the lesser spotted catshark, Scyliorhinus canicula., Results: We generated a mutli-tissue assembly comprising 86,006 contigs, of which 44,794 were assigned to a particular tissue or combination of tissues based on mapping of sequencing reads. We have characterised transcripts encoding genes involved in insulin regulation, glucose sensing, transcriptional regulation, signaling and digestion, as well as many peptide hormone precursors and their receptors for the first time. Comparisons to mammalian pancreas transcriptomes reveals that mechanisms of glucose sensing and insulin regulation used to establish and maintain a stable internal environment are conserved across jawed vertebrates and likely pre-date the vertebrate radiation. Conservation of pancreatic hormones and genes encoding digestive proteins support the single, early evolution of a distinct pancreatic gland with endocrine and exocrine functions in jawed vertebrates. In addition, we demonstrate that chondrichthyes lack pancreatic polypeptide (PP) and that reports of PP in the literature are likely due cross-reaction with PYY and/or NPY in the pancreas. A three hormone islet organ is therefore the ancestral jawed vertebrate condition, later elaborated upon only in the tetrapod lineage., Conclusions: The cartilaginous fish are a great untapped resource for the reconstruction of patterns and processes of vertebrate evolution and new approaches such as those described in this paper will greatly facilitate their incorporation into the rank of "model organism".

Snake venom has been hypothesized to have originated and diversified through a process that involves duplication of genes encoding body proteins with subsequent recruitment of the copy to the venom gland, where natural selection acts to develop or increase toxicity. However, gene duplication is known to be a rare event in vertebrate genomes, and the recruitment of duplicated genes to a novel expression domain (neofunctionalization) is an even rarer process that requires the evolution of novel combinations of transcription factor binding sites in upstream regulatory regions. Therefore, although this hypothesis concerning the evolution of snake venom is very unlikely and should be regarded with caution, it is nonetheless often assumed to be established fact, hindering research into the true origins of snake venom toxins. To critically evaluate this hypothesis, we have generated transcriptomic data for body tissues and salivary and venom glands from five species of venomous and nonvenomous reptiles. Our comparative transcriptomic analysis of these data reveals that snake venom does not evolve through the hypothesized process of duplication and recruitment of genes encoding body proteins. Indeed, our results show that many proposed venom toxins are in fact expressed in a wide variety of body tissues, including the salivary gland of nonvenomous reptiles and that these genes have therefore been restricted to the venom gland following duplication, not recruited. Thus, snake venom evolves through the duplication and subfunctionalization of genes encoding existing salivary proteins. These results highlight the danger of the elegant and intuitive "just-so story" in evolutionary biology., (© The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Background: Rapid access chest pain clinics have facilitated the early diagnosis and treatment of patients with coronary heart disease and angina. Despite this important service provision, coronary heart disease continues to be under-diagnosed and many patients are left untreated and at risk. Recent advances in imaging technology have now led to the widespread use of noninvasive computed tomography, which can be used to measure coronary artery calcium scores and perform coronary angiography in one examination. However, this technology has not been robustly evaluated in its application to the clinic., Methods/design: The SCOT-HEART study is an open parallel group prospective multicentre randomized controlled trial of 4,138 patients attending the rapid access chest pain clinic for evaluation of suspected cardiac chest pain. Following clinical consultation, participants will be approached and randomized 1:1 to receive standard care or standard care plus ≥64-multidetector computed tomography coronary angiography and coronary calcium score. Randomization will be conducted using a web-based system to ensure allocation concealment and will incorporate minimization. The primary endpoint of the study will be the proportion of patients diagnosed with angina pectoris secondary to coronary heart disease at 6 weeks. Secondary endpoints will include the assessment of subsequent symptoms, diagnosis, investigation and treatment. In addition, long-term health outcomes, safety endpoints, such as radiation dose, and health economic endpoints will be assessed. Assuming a clinic rate of 27.0% for the diagnosis of angina pectoris due to coronary heart disease, we will need to recruit 2,069 patients per group to detect an absolute increase of 4.0% in the rate of diagnosis at 80% power and a two-sided P value of 0.05. The SCOT-HEART study is currently recruiting participants and expects to report in 2014., Discussion: This is the first study to look at the implementation of computed tomography in the patient care pathway that is outcome focused. This study will have major implications for the management of patients with cardiovascular disease., Trial Registration: ClinicalTrials.gov Identifier: NCT01149590.

Unlabelled: We report the case of a 21-year-old male whose frequent episodes of loss of consciousness in the dental surgery culminated in the postponement of treatment, pending further investigation. The patient was referred to a cardiologist and submitted to head-up tilt testing, which evoked prolonged asystole, associated with loss of consciousness and mild generalized twitching, confirming a diagnosis of malignant vasovagal syncope. Before dental treatment could be completed, the patient was successfully treated with disopyramide and dual-chamber pacemaker implantation., Clinical Relevance: Dentistry can predispose patients to fainting (syncope or vasovagal episode) owing to fear, pain, unusual sights and smells, anxiety, fatigue and fasting, so knowledge of extreme forms of this response are of relevance.

Background: Management of patients with an acute coronary syndrome (ACS) requires accurate risk stratification to guide appropriate therapy., Aim: To assess the utility of the TIMI risk score in stratifying patients with possible ACS in routine clinical practice., Design: Prospective observational study., Methods: We recruited 869 consecutive patients with a diagnosis of possible ACS attending the acute medical receiving unit of a district general hospital. The main outcome measures were recurrent myocardial infarction, urgent revascularization, and all-cause mortality. TIMI risk score was calculated for each patient, and each was also assigned a risk group based on electrocardiogram (ECG) changes and troponin levels only. After follow-up, Cox univariate and multivariate regression was used to evaluate the influence of potential risk factors on duration of event-free survival, and likelihood ratio tests to assess the fit of the models., Results: Increasing TIMI risk score was associated with increased risk of events (p<0.001), as was higher risk group from ECG plus troponin stratification (p<0.001). The likelihood ratio comparison favoured the TIMI risk score (difference 13.910, 5 degrees of freedom, p = 0.016)., Discussion: The TIMI risk score is a valid tool for risk stratification in unselected cases with possible acute coronary syndrome. It is superior to ECG changes and troponin alone, although this simpler method also achieves good risk stratification.

Objectives: To compare the presenting complaint, risk factors, and outcome of suspected acute coronary syndrome (ACS) in those aged 65 and older with those of a younger cohort., Design: Prospective observational cohort study., Setting: A typical Scottish district general hospital covering a population of 150,000., Participants: Patients presenting with suspected ACS (N=869) over a 6-month period., Measurements: Main presenting complaint and major risk factors including electrocardiogram (ECG) changes. Primary outcome measures were percutaneous coronary intervention, recurrent myocardial infarction, and death at 3-month follow-up., Results: Four hundred seventy-seven (55%) were aged 65 and older. Older patients were less likely to present with chest pain and more likely to present with breathlessness or collapse. They had fewer major risk factors for heart disease. There was a higher proportion with ischemic ECG changes, elevated troponin, and major acute coronary events at follow-up. Older patients were less likely to be accepted for angiography even though they were more likely than the younger cohort to have significant coronary artery disease when angiography was performed (chi-square test, P<.01 for all above)., Conclusion: Older patients with suspected ACS were more likely to present atypically and have worse outcomes than their younger counterparts, despite having fewer major risk factors. The results highlight the importance of age as a predictor of adverse outcome and suggest that clinicians need to ensure equitable access to angiography for older patients.

Cor triatriatum and imperforate anus are rare. We describe, for the first time, the coexistence of these conditions in a 43 year old woman.

Objective: to examine the effects and feasibility of educating and empowering older people with ischaemic heart disease using trained senior lay health mentors., Design: randomised controlled trial with blinded evaluation., Setting: Falkirk and District Royal Infirmary., Participants: inpatients and outpatients aged 60 or over attending secondary care with a diagnosis of angina or acute myocardial infarction. Three-hundred and nineteen entered and 289 completed exit assessments. The intervention group took part in mentoring groups for 1 year, meeting monthly for 2 hours, each led by two trained lay health mentors in addition to standard care., Main Outcome Measures: primary outcome measures were changes in coronary risk factors, medication usage and actual use of secondary care health services. Secondary outcomes were total and cardiovascular events; changes in medication compliance, non-medical support requirement, health status and psychological functioning, and social inclusion., Results: there were significant improvements in a reported current exercise score (mean +0.33, +0.02 to +0.52), in the average time spent walking per week by 72 minutes (+1 to +137 minutes), and in the SF36 Physical Functioning Score (+6.1, +2.4 to +9.5). There was a 1.0% reduction in total fat (95% CI -3.0% to -0.6%) and a 0.6% reduction in saturated fat (95% CI -1.5% to -0.03%). The intervention group showed reduced outpatient attendance for coronary heart disease (-0.25 appointments, -0.61 to -0.08). Attendance rates were high. Socio-economic grouping did not affect participation., Conclusions: Lay Health Mentoring is feasible, practical and inclusive, positively influencing diet, physical activity, and health resource utilisation in older subjects with ischaemic heart disease without causing harm.

Percutaneous balloon dilatation of the pulmonary valve resulted in long lasting benefit in a 40-year-old patient with carcinoid heart disease. Concomitant aggressive therapy for her metastatic carcinoid tumour may explain why the clinical outcome was better than previous reports.

Objective: To assess the influence of vasodilator treatment started early after myocardial infarction on left ventricular size and function., Setting: Coronary care unit, Royal Infirmary, Edinburgh., Patients: 105 patients with acute myocardial infarction (systolic blood pressure > 90 mm Hg) were randomised within 24 hours of the start of pain. Unlike previous studies 88% of the patients received thrombolysis., Methods: Double blind randomised placebo controlled study with either 12.5 mg of captopril three times daily or 20 mg of isosorbide mononitrate three times daily for 28 days., Main Outcome Measures: Clinical outcome and left ventricular size and function assessed by echocardiography, radionuclide ventriculography, and magnetic resonance imaging., Results: There was no difference in left ventricular size or function in either treatment group as measured one week after the end of the trial. Even the placebo group tended to decrease left ventricular diameter over the four week study period (one week: 5.0 (0.1) v, five weeks: 4.8 (0.1) cm, NS). Four patients had an adverse clinical outcome in the placebo group whereas no adverse outcome was seen in the captopril group., Conclusions: Vasodilator treatment may be of limited value or of no benefit for most infarct patients, particularly those treated with thrombolytic agents. Captopril, however, may benefit patients at high risk.

Glyceryl trinitrate (GTN) is known to be a potent venodilator, but the effects might differ depending on the regime of administration. Using a radionuclide blood pool method we examined the changes in peripheral (and pulmonary) venous volume induced by GTN administered in three ways: short (4 min) intravenous infusions at 75 micrograms.min-1 (n = 7), prolonged intravenous infusion at 50 micrograms.min-1 (n = 7) or 500 micrograms sublingual tablet (n = 5). Sublingual GTN and the prolonged infusion caused similar decreases in systolic blood pressure (-23 +/- 12, -24 +/- 10 mmHg) and increases in calf venous volume (12 +/- 4%, 12 +/- 5%). For both, the peak effect occurred around 20 min after starting GTN administration (blood pressure 18 +/- 12 vs 25 +/- 12 min, venous volume 21 +/- 1 vs 22 +/- 7 min). Only the prolonged infusion caused a significant fall in diastolic pressure (-14 +/- 6 mmHg). The short infusion had a similar effect on systolic pressure (-21 +/- 16 mmHg) to the other two regimes, but caused a significantly smaller increase in venous volume (6 +/- 2%), which occurred much earlier (5 +/- 2 min). Anterior lung blood volume decreased in response to intravenous GTN and the posterior lung blood volume did not change, suggesting this alteration was secondary to peripheral venodilatation. In conclusion, GTN causes venous dilatation at low levels of delivery with the maximum response occurring after 20 min. In contrast, arterial effects are seen more rapidly and at higher rates of delivery.

Objective: To investigate the peripheral venous response to head up tilting in malignant vasovagal syndrome., Patients: 31 Patients with unexplained syncope or dizziness referred from the cardiology department., Methods: Changes in calf venous volume were studied by a radionuclide technique during 45 degrees head up tilt testing., Results: During tilt testing six patients became syncopal but 25 were symptom free. The syncopal group had greater increases in calf venous volume after the change in posture and perhaps more importantly considerably less variability in the venous volume during the tilted period., Conclusions: The venous response was different in the syncopal patients. The lack of response of the peripheral venous circulation to changes in the central circulation may be responsible for triggering the Bezold-Jarisch reflex and malignant vasovagal syncope.

The insulin response to a standard oral glucose tolerance test (OGTT) and other anthropometric and biochemical risk factors for coronary heart disease (CHD) were measured in a random sample of 107 Edinburgh men, who were initially studied in 1976 when they were 40 and who were reexamined in 1988-89. Fasting glucose and glucose response to OGTT were higher in 1988-89 than in 1976. In contrast, insulin levels did not differ between the initial and follow-up study either before or after the glucose load. Body mass indices increased, except triceps skinfold. Changing patterns in both fasting and OGTT insulin or glucose levels in individuals were related to changes in bodyweight or in subscapular skinfolds. Modifications in serum total and HDL cholesterol were related to changes in fasting insulin and insulin area, respectively, but not to glucose data. Eleven men developed clinical CHD. Neither glucose nor insulin measures obtained in 1976 differed between those with and without CHD. Weight-height index and abdominal skin-folds were higher in those with CHD. HDL cholesterol was significantly lower (P less than 0.05). Abdominal skin-fold but not body mass index remained significant when adjusted for HDL cholesterol. This small study confirms the importance of central obesity and low HDL cholesterol but failed to identify insulin as a risk factor for CHD in this Scottish population.

Objective: To investigate long term changes in total cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol concentrations and in measures of other risk factors for coronary heart disease and to assess their importance for the development of coronary heart disease in Scottish men., Design: Longitudinal study entailing follow up in 1988-9 of men investigated during a study in 1976., Setting: Edinburgh, Scotland., Subjects: 107 men from Edinburgh who had taken part in a comparative study of risk factors for heart disease with Swedish men in 1976 when aged 40., Intervention: The men were invited to attend a follow up clinic in 1988-9 for measurement of cholesterol concentrations and other risk factor measurements. Eighty three attended and 24 refused to or could not attend., Main Outcome Measures: Changes in total cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol concentrations, body weight, weight to height index, prevalence of smoking, and alcohol intake; number of coronary artery disease events., Results: Mean serum total cholesterol concentration increased over the 12 years mainly due to an increase in the low density lipoprotein cholesterol fraction (from 3.53 (SD 0.09) to 4.56 (0.11) mmol/l) despite a reduction in high density lipoprotein cholesterol concentration. Body weight and weight to height index increased. Fewer men smoked more than 15 cigarettes/day in 1988-9 than in 1976. Blood pressure remained stable and fasting triglyceride concentrations did not change. The frequency of corneal arcus doubled. Alcohol consumption decreased significantly. Eleven men developed clinical coronary heart disease. High low density lipoprotein and low high density lipoprotein cholesterol concentrations in 1976, but not total cholesterol concentration, significantly predicted coronary heart disease (p = 0.05). Almost all of the men who developed coronary heart disease were smokers (91% v 53%, p less than 0.05)., Conclusion: Over 12 years the lipid profile deteriorated significantly in this healthy cohort of young men. Smoking, a low high density lipoprotein concentration and a raised low density lipoprotein concentration were all associated with coronary heart disease in middle aged Scottish men, whereas there was no association for total cholesterol concentration. The findings have implications for screening programmes.

In vivo, apoptotic cells are swiftly recognized by phagocytes, presumably because of changes on their surface. This article describes surface changes in rat cortical thymocytes undergoing apoptosis induced by glucocorticoid treatment in vitro. Homogeneous populations of thymocytes early in apoptosis were prepared by isopyknic centrifugation. These cells were compared with purified nonapoptotic cells in terms of several surface characteristics, including binding to macrophages, surface ultrastructure, microelectrophoretic mobility (a measure of surface charge density), and ability to bind four lectins and four monoclonal antibodies to thymocyte antigens. Apoptotic cells bound to macrophages more avidly than did nonapoptotic cells by a process not dependent upon serum factors. Their surfaces lost microvilli and became " blistered ," apparently through fusion of vesicles of endoplasmic reticulum with the plasma membrane. The surface charge density of apoptotic cells was less than that of nonapoptotic cells. Surface antigens and lectin-binding sites were less abundant on apoptotic than on normal cells, in proportion to the general reduction in cell size observed in apoptosis. Differences between apoptotic and normal cells were not detected, however, in the relative quantities of exposed galactose, N-acetyl galactosamine, N-acetyl glucosamine, N-acetyl neuraminic acid, or of several surface antigens, including the major sialoglycoproteins of the thymocyte membrane. It appears that although several changes occur in the surface of apoptotic cells, many cell membrane structures remain intact. The changes responsible for the recognition of apoptotic cells by phagocytes are more subtle than those detectable by the binding of lectin and antibody probes, but preliminary data suggest that a lectin-sugar interaction is involved.

Murine lymphoid cell lines and rat thymocytes treated in vitro with glucocorticoid hormones provide a convenient system for studying the nuclear changes in apoptosis. Morphologically the nucleolus disintegrates and chromatin undergoes an unusual generalized condensation. This is associated with excision of most of the nuclear DNA to short but well-organized chains of nucleosomes, apparently by an endogenous non-lysosomal nuclease. The process is dependent upon macromolecular synthesis and probably is mediated, at least remotely, by the classical steroid-receptor-gene activation pathway. A similar process of chromatin condensation and excision can be produced by the calcium-magnesium ionophore A23187. In other circumstances of 'programmed cell death', analogous chromatin condensation, excision and requirements for macromolecular synthesis have been documented.