The Fish in the Turtle: On the Functionality of the Oropharynx in the Common Musk Turtle Sternotherus odoratus (Chelonia,Kinosternidae) Concerning Feeding and Underwater Respiration

In tetrapods, the oropharyngeal cavity and its anatomical structures are mainly, but not exclusively, responsible for the uptake and intraoral transport of food. In this study, we provide structural evidence for a second function of the oropharynx in the North American common musk turtle, Sternotherus odoratus, Kinosternidae: aquatic gas exchange. Using high‐speed video, we demonstrate that S. odoratus can grasp food on land by its jaws, but is afterward incapable of lingual based intraoral transport; food is always lost during such an attempt. Scanning electron microscopy and light microscopy reveal that the reason for this is a poorly developed tongue. Although small, the tongue bears a variety of lobe‐like papillae, which might be misinterpreted as an adaptation for terrestrial food uptake. Similar papillae also cover most of the oropharynx. They are highly vascularized as shown by light microscopy and may play an important role in aquatic gas exchange. The vascularization of the oropharyngeal papillae in S. odoratus is then compared with that in Emys orbicularis, an aquatic emydid with similar ecology but lacking the ability of underwater respiration. Oropharyngeal papillae responsible for aquatic respiration are also found in soft‐shelled turtles (Trionychidae), the putative sister group of the kinosternids. This trait could therefore represent a shared, ancestral character of both groups involving advantages in the aquatic environment they inhabit. Anat Rec 293:1416–1424, 2010. © 2010 Wiley‐Liss, Inc.     

Breakdown of calcium homeostasis in relation to tissue depolarization: comparison between gray and white matter ischemia.

In vitro studies suggest that ischemic injury of cerebral white matter is mediated by nonsynaptic cellular mechanisms, such as Ca2+ entry into axons through reversal of the Na+ -Ca2+ exchanger. The authors investigated extracellular Ca2+ concentration in relation to tissue depolarization (direct current potential) in vivo using ion-selective electrodes in cortical gray and subcortical white matter of alpha-chloralose-anesthetized cats during 120 minutes of global cerebral ischemia. On induction of ischemia, regional CBF, as measured by hydrogen clearance, ceased. The direct current potential decreased rapidly within minutes in gray matter and with little time delay in white matter. Extracellular Ca2+ concentration decreased just as quickly in gray matter. In white matter, in contrast, extracellular Ca2+ increased in the first 20 to 30 minutes, and a delayed and much slower decline, compared with gray matter, was observed thereafter, reaching a minimal level only about 60 minutes after occlusion. Our results suggest that smaller and delayed transmembrane shifts of Ca2+ are correlates of delayed ischemic membrane dysfunction in central white matter tracts, which may be explained by a lack of synaptic mechanisms.     

Early [(11)C]Flumazenil/H(2)O positron emission tomography predicts irreversible ischemic cortical damage in stroke patients receiving acute thrombolytic therapy

BACKGROUND AND PURPOSE: Central benzodiazepine receptor ligands, such as [(11)C]flumazenil (FMZ), are markers of neuronal integrity and therefore might be useful in the differentiation of functionally and morphologically damaged tissue early in ischemic stroke. We sought to assess the value of a benzodiazepine receptor ligand for the early identification of irreversible ischemic damage to cortical areas that cannot benefit from reperfusion. METHODS: Eleven patients (7 male, 4 female, aged 52 to 75 years) with acute, hemispheric ischemic stroke were treated with alteplase (recombinant tissue plasminogen activator; 0.9 mg/kg according to National Institute of Neurological Disorders and Stroke protocol) within 3 hours of onset of symptoms. At the beginning of thrombolysis, cortical cerebral blood flow ([(15)O]H(2)O) and FMZ binding were assessed by positron emission tomography (PET). Those early PET findings were related to the change in neurological deficit (National Institutes of Health Stroke Scale) and to the extent of cortical damage on MRI or CT 3 weeks after the stroke. RESULTS: Hypoperfusion was observed in all cases, and in 8 patients the values were below critical thresholds estimated at 12 mL/100 g per minute, comprising 1 to 174 cm(3) of cortical tissue. Substantial reperfusion was seen in most of these regions 24 hours after thrombolysis. In 4 cases, distinct areas of decreased FMZ binding were detected. Those patients suffered permanent lesions in cortical areas corresponding to their FMZ defects (112 versus 146, 3 versus 3, 2 versus 1, and 128 versus 136 cm(3)). In the other patients no morphological defects were detected on MRI or CT, although blood flow was critically decreased in areas ranging in size up to 78 cm(3) before thrombolysis. CONCLUSIONS: These findings suggest that imaging of benzodiazepine receptors by FMZ PET distinguishes between irreversibly damaged and viable penumbra tissue early after acute stroke.     

Angiogenesis and Brain Oedema in Intracranial Meningiomas: Influence of Vascular Endothelial Growth Factor

Summary The correlation between angiographic neovascularization, peritumoural brain oedema (PTBOe) and the expression of vascular endothelial growth factor (VEGF) , was analysed in 30 patients with intracranial meningiomas. Pre-operative angiograms were examined for the existence of either an exclusively dural tumour blush or an additionally pial tumour supply from cerebral arteries. Furthermore the presence of macroscopic tumour-neovascularization and dysplastic changes of tumour-draining cerebral veins was evaluated. VEGF expression was investigated on histological tissue samples, using immunohistochemical techniques. VEGF immunohistochemistry and neuroradiological evaluations were performed in double blind fashion. Tumour volume and the amount of oedema were calculated by computerized tomography (CT) or magnetic resonance imaging (MRI). The oedema-tumour volume ratio was defined as oedema index (OeI). Compared to VEGF-negative meningiomas, tumours with striking VEGF staining revealed a significant higher mean oedema index (OeI=4,2 vs. OeI=1,5; p<0.018), and a higher oedema incidence (91,7% vs. 44,4%; p<0.046). Equally, meningiomas with additionally tumour supply from cerebral arteries were associated with a significant higher mean OeI (OeI=4.1 vs. OeI=1.2; p<0.01) and oedema incidence (94,7% vs. 20,0%; p<0,0023) than meningiomas with exclusively tumour supply from dural arteries. All meningiomas with striking VEGF-expression were associated with vascular tumour supply from cerebral arteries, but VEGF-negative tumours only in 50% (p<0.029). These data suggest a link between VEGF-expression, arterial tumour supply and peritumoural brain oedema. The development of tumour supply from cerebral arteries may be important for formation of meningioma-related oedema. Therefore, VEGF may represent a potent mediator in the evolution of this type of vascularization in meningiomas.     

Elevated fasting insulin predicts incident hypertension: the ARIC study. Atherosclerosis Risk in Communities Study Investigators.

OBJECTIVE: The prospective association of insulin and hypertension has been under debate in the context of the development of the insulin resistance or multiple metabolic syndrome. We examined the predictive associations of fasting serum insulin with incident hypertension occurring alone or as part of the multiple metabolic syndrome. DESIGN: Analyses were restricted to 5221 middle-aged participants of the Atherosclerosis Risk in Communities Study cohort who were free of component disorders of the multiple metabolic syndrome (hypertension; diabetes; high triglycerides and/or low HDL cholesterol (dyslipidaemias)) at baseline. OUTCOME: A total of 1018 individuals developed hypertension, 801 in the absence of components of the metabolic syndrome and 217 in combination with diabetes or dyslipidaemias, between 1987 and 1993. RESULTS: Elevated fasting insulin (top quartile versus lowest quartile) was associated with overall incident hypertension in European Americans [hazard rate ratio (HRR) 2.0, 95% confidence interval (CI) 1.7-2.4] but the results were inconclusive in African Americans (HRR 1.3, 95% CI 0.9-1.8) after adjustment for age, gender and study centre. Among European Americans, body mass index and abdominal girth only partly explained the observed association. Elevated fasting insulin was more strongly predictive of hypertension occurring as a component of the multiple metabolic syndrome (HRR 2.4, 95% CI 1.5-3.9) than of hypertension occurring alone (HRR 1.3, 95% CI 1.0-1.7) adjusting statistically for age, gender, study centre, body mass index and abdominal girth. CONCLUSIONS: The results are consistent with the concept of an aetiological heterogeneity for hypertension and may explain previously reported inconsistent findings on the association of insulin with incident hypertension.