Abdominal pain with a twist

Malrotation in children is due to either an incomplete or non-rotation of the foetal mid-gut during perinatal development. Presentation is usually in the first few weeks of life, often with life-threatening volvulus and ischaemia. However, it can be a rare cause of abdominal pain in older children and young adults. We present such a case, as a reminder to emergency physicians that malrotation should be considered in the differential diagnosis of recurrent or chronic abdominal pain not only in children but also in adolescents

Climatic and topographic changes since the Miocene influenced the diversification and biogeography of the tent tortoise (Psammobates tentorius) species complex in Southern Africa

Background: Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotspots in the world, the Succulent Karoo and Cape Floristic Region. The highly diverged P. tentorius represents an excellent model species for exploring biogeographic and radiation patterns of reptiles in Southern Africa. Results: We investigated genetic structure and radiation patterns against temporal and spatial dimensions since the Miocene in the Psammobates tentorius species complex, using multiple types of DNA markers and niche modelling analyses. Cladogenesis in P. tentorius started in the late Miocene (11.63–5.33 Ma) when populations dispersed from north to south to form two geographically isolated groups. The northern group diverged into a clade north of the Orange River (OR), followed by the splitting of the group south of the OR into a western and an interior clade. The latter divergence corresponded to the intensifcation of the cold Benguela current, which caused western aridifcation and rainfall seasonality. In the south, tectonic uplift and subsequent exhumation, together with climatic fuctuations seemed responsible for radiations among the four southern clades since the late Miocene. We found that each clade occurred in a habitat shaped by diferent climatic parameters, and that the niches difered substantially among the clades of the northern group but were similar among clades of the southern group. Conclusion: Climatic shifts, and biome and geographic changes were possibly the three major driving forces shaping cladogenesis and genetic structure in Southern African tortoise species. Our results revealed that the cladogenesis of the P. tentorius species complex was probably shaped by environmental cooling, biome shifts and topographic uplift in Southern Africa since the late Miocene. The Last Glacial Maximum (LGM) may have impacted the distribution of P. tentorius substantially. We found the taxonomic diversify of the P. tentorius species complex to be highest in the Greater Cape Floristic Region. All seven clades discovered warrant conservation attention, particularly Ptt-B–Ptr, Ptt-A and Pv-

The Tnt1 Retrotransposon Escapes Silencing in Tobacco, Its Natural Host

Retrotransposons' high capacity for mutagenesis is a threat that genomes need to control tightly. Transcriptional gene silencing is a general and highly effective control of retrotransposon expression. Yet, some retrotransposons manage to transpose and proliferate in plant genomes, suggesting that, as shown for plant viruses, retrotransposons can escape silencing. However no evidence of retrotransposon silencing escape has been reported. Here we analyze the silencing control of the tobacco Tnt1 retrotransposon and report that even though constructs driven by the Tnt1 promoter become silenced when stably integrated in tobacco, the endogenous Tnt1 elements remain active. Silencing of Tnt1-containing transgenes correlates with high DNA methylation and the inability to incorporate H2A.Z into their promoters, whereas the endogenous Tnt1 elements remain partially methylated at asymmetrical positions and incorporate H2A.Z upon induction. Our results show that the promoter of Tnt1 is a target of silencing in tobacco, but also that endogenous Tnt1 elements can escape this control and be expressed in their natural host

Sympathetic Activation and Baroreflex Function during Intradialytic Hypertensive Episodes

BACKGROUND: The mechanisms of intradialytic increases in blood pressure are not well defined. The present study was undertaken to assess the role of autonomic nervous system activation during intradialytic hypertensive episodes. METHODOLOGY/PRINCIPAL FINDINGS: Continuous interbeat intervals (IBI) and systolic blood pressure (SBP) were monitored during hemodialysis in 108 chronic patients. Intradialytic hypertensive episodes defined as a period of at least 10 mmHg increase in SBP between the beginning and the end of a dialysis session or hypertension resistant to ultrafiltration occurring during or immediately after the dialysis procedure, were detected in 62 out of 113 hemodialysis sessions. SBP variability, IBI variability and baroreceptor sensitivity (BRS) in the low (LF) and high (HF) frequency ranges were assessed using the complex demodulation technique (CDM). Intradialytic hypertensive episodes were associated with an increased (n = 45) or decreased (n = 17) heart rate. The maximal blood pressure was similar in both groups. In patients with increased heart rate the increase in blood pressure was associated with marked increases in SBP and IBI variability, with suppressed BRS indices and enhanced sympatho-vagal balance. In contrast, in those with decreased heart rate, there were no significant changes in the above parameters. End-of-dialysis blood pressure in all sessions associated with hypertensive episode was significantly higher than in those without such episodes. In logistic regression analysis, predialysis BRS in the low frequency range was found to be the main predictor of intradialytic hypertension. CONCLUSION/SIGNIFICANCE: Our data point to sympathetic overactivity with feed-forward blood pressure enhancement as an important mechanism of intradialytic hypertension in a significant proportion of patients. The triggers of increased sympathetic activity during hemodialysis remain to be determined. Intradialytic hypertensive episodes are associated with higher end-of-dialysis blood pressure, suggesting that intradialytic hypertension may play a role in generation of interdialytic hypertension

The multi-peak adaptive landscape of crocodylomorph body size evolution

Background: Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller ( Results: Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent an essentially continual decline since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions. Conclusions: Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution on large phylogenetic and temporal scales, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.</p

Má rotação intestinal em adulto, relato de caso e revisão da literatura Adult intestinal malrotation, case report and literature review

INTRODUÇÃO: Má rotação intestinal é entidade clínico-cirúrgica que faz parte do cotidiano do cirurgião pediátrico, mas que se torna um desafio diagnóstico quando desenvolve sintomas em adolescentes e adultos. RELATO DO CASO: Mulher deu entrada no hospital com quadro de intensa dor abdominal com três dias de evolução e piora progressiva nas últimas 24 horas. A dor apresentava piora importante após as refeições, quando era acompanhada de náuseas e vômitos. Ao exame físico apresentava-se em bom estado gera, abdômen plano, flácido, ruídos presentes, levemente doloroso à palpação de epigástrio, mas sem sinais de irritação peritoneal. Exames laboratoriais encontravam-se dentro dos limites da normalidade, bem como estudo ultrassonográfico. Não houve melhora clínica apesar do tratamento instituído e optou-se por investigação cirúrgica por tomografia sugerir má rotação intestinal. No intra-operatório observou-se todo o intestino delgado disposto para o lado direito do abdômen e o cólon para o lado esquerdo. Além disto, o jejuno proximal encontrava-se isquêmico e fazendo um volvo de 720º sobre o eixo dos vasos mesentéricos superiores. Para a correção da anomalia fez-se enterotomia do jejuno proximal, a cerca de 10 cm do ligamento de Treitz, e desconfecção do volvo, o que cursou com melhora progressiva da isquemia intestinal, permitindo que se fizesse enteroanastomose. Realizou-se ligadura do pedículo da artéria cólica média em sua origem e colectomia direita seguida de anastomose íleo-transversa látero-lateral. A paciente evolui bem. CONCLUSÃO: - A má rotação intestinal em adultos é doença de difícil diagnóstico primário, devido a não constar entre as hipóteses diagnósticas iniciais do cirurgião geral.<br>INTRODUCTION: Intestinal malrotation is a clinical surgical entity that is present in the everyday practice of the pediatric surgeon. However, it becomes a diagnostic challenge when symptoms develop in adolescents and adults. CASE REPORT: A woman presented to the hospital with intense abdominal pain of three days' duration and progressive worsening over the preceding 24 hours. The pain increased markedly after meals, accompanied by nausea and vomiting. On physical examination, the patient was in good general health, her abdomen was flat, flaccid, with normal bowel sounds, and tender to palpation of the epigastrium, yet with no signs of peritoneal irritation. Laboratory test results were within the limits of normal, as was ultrasonography. No clinical improvement was achieved despite the treatment instituted; surgical exploration was chosen as tomography was suggestive of intestinal malrotation. Intraoperatively, all the small intestine was found to be positioned to the right side of the abdomen and the colon, to the left side. In addition, the proximal jejunum was ischemic and forming a volvulus of 720º over the axis of the superior mesenteric vessels. In order to correct the anomaly, enterotomy of the proximal jejunum was performed at approximately 10 cm from the ligament of Treitz, and the volvulus was corrected. This promoted a progressive improvement of the intestinal ischemia, which made enteroanastomosis possible. The middle colic artery pedicle was ligated at its root and a right colectomy was performed, followed by a side-to-side ileo-transverse anastomosis. The patient is doing well. CONCLUSION: Intestinal malrotation in adults is a condition of difficult primary diagnosis, since it is not among the initial diagnostic hypotheses of the general surgeon