5’-adenosine monophosphate mediated cooling treatment enhances ΔF508-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) stability in vivo

Background

Gene mutations that produce misprocessed proteins are linked to many human disorders. Interestingly, some misprocessed proteins retained their biological function when stabilized by low temperature treatment of cultured cells in vitro. Here we investigate whether low temperature treatment in vivo can rescue misfolded proteins by applying 5’-AMP mediated whole body cooling to a Cystic Fibrosis (CF) mouse model carrying a mutant cystic fibrosis transmembrane conductance regulator (CFTR) with a deletion of the phenylalanine residue in position 508 (ΔF508-CFTR). Low temperature treatment of cultured cells was previously shown to be able to alleviate the processing defect of ΔF508-CFTR, enhancing its plasma membrane localization and its function in mediating chloride ion transport.

Results

Here, we report that whole body cooling enhanced the retention of ΔF508-CFTR in intestinal epithelial cells. Functional analysis based on β-adrenergic dependent salivary secretion and post-natal mortality rate revealed a moderate but significant improvement in treated compared with untreated CF mice.

Conclusions

Our findings demonstrate that temperature sensitive processing of mutant proteins can be responsive to low temperature treatment in vivo.     

Lésion vertébrale froide en TEP/TDM au FNa-(18F) : n’oubliez pas l’ostéonécrose vertébrale (ou maladie de Kümmell) !

A 75-year-old woman presented with a history of severe backache and spinal cord compression syndrome. MRI revealed a well-circumscribed, homogeneous, wedge-shaped lesion involving T11 vertebral body, which was hypointense on T1- and hyperintense on T2-weighted images with bulging posterior border. Patient benefited from a decompressive T10–T12 laminectomy. Four months later, a new vertebral collapse of T10 was evidenced on plain X-rays. A second MRI exam displayed worrisome diffuse signal abnormalities of T10 pointing to a space-occupying lesion. A (18F)-NaF PET/CT was ordered and disclosed an hypometabolic (“cold”) activity of T10 and T11 vertebral bodies with a partial postero-lateral hypermetabolic rim. Twined low dose CT evidenced fracture sequelae and air-filled cleft within vertebral bodies. Histopathologic examination of the biopsy specimen of T10 revealed thinned out trabeculae surrounded by hyalinized fatty marrow cells and fibrovascular tissue, thus ascertaining the diagnosis of avascular necrosis of the vertebra. The radiographic and CT sine qua non for Kümmell's disease is intraosseous vacuum phenomenon. That is to say, vacuum clefts (VCs) of the vertebral bodies are radiographically recognized as a vacuum or air-filled cleft within the collapsed vertebrae. This sign is felt to be suggestive of ischemic necrosis but not specific as VCs of the vertebral bodies have also been associated with delayed union or non-union of osteoporotic fractures. Because of often misleading MRI abnormalities, integrative interpretation of (18F)-NaF PET/CT pattern should be undertaken in order to suspect Kümmell's disease and to discard some of the differentials.     

3-Iodothyronamine: a novel hormone controlling the balance between glucose and lipid utilisation

3-Iodothyronamine is considered as a derivate of thyroid hormone as a result of enzymatic deiodination and decarboxylation. The physiological role of thyronamine (T1AM) is not known. The aim of this study was to analyze the metabolic response to T1AM in the Djungarian hamster Phodopus sungorus. We measured the influence of T1AM (50 mg/kg) on metabolic rate (VO₂), body temperature (T _b) and respiratory quotient (RQ) in this species and in BL/6 mice. T1AM treated hamsters as well as the mice showed a rapid decrease in VO₂ and T _b, accompanied by a reduction of RQ from normal values of about ∼0.9 to ∼0.70 for several hours. This indicates that carbohydrate utilisation is blocked by the injection of T1AM and that metabolic pathways are rerouted from carbohydrate to lipid utilisation in response to T1AM. This assumption was further supported by the observation that the treatment of T1AM caused ketonuria and a significant loss of body fat. Our results indicate that T1AM has the potential to control the balance between glucose and lipid utilisation in vivo.     

An interictal measurement of cerebral oxygen extraction fraction in MRI-negative refractory epilepsy using quantitative susceptibility mapping

PurposeOxygen extraction fraction (OEF) can be a factor to identify brain tissue’s disability in epileptic patients. This study aimed to assess the OEF’s level measurement in refractory epileptic patients (REPs) using a quantitative susceptibility mapping (QSM) method and to determine whether the OEF parameters change.MethodsQSM-OEF maps of 26 REPs and 16 healthy subjects were acquired using 3T MRI with a 64-channel coil. Eighteen regions-of-interest (ROIs) were chosen around the cortex in one appropriate slice of the brain and the mean QSM-OEF for each ROI was obtained. The correlations of QSM-OEF among different clinical characteristics of the disease, as well as between the patients and normal subjects, were also investigated.ResultsQSM-OEF was shown to be significantly higher in REPs (44.9 ± 5.8) than that in HS (41.9 ± 6.2) (p < 0.05). Mean QSM-OEF was statistically lower in the ipsilateral side (44.5 ± 6.6) compared to the contralateral side (46.4 ± 6.8) (P < 0.01). QSM-OEF was illustrated to have a strong positive correlation with the attack duration (r = 0.6), and a moderate negative correlation with the attack frequency (r = −0.3). Using an optimized support vector machine algorithm, we could predict the disease in subjects having abnormal OEF values in the brain-selected-ROIs with sensitivity, specificity, AUC, and the precision of 0.96, 1, 0.98, and 1, respectively.ConclusionsThe results of this study revealed that QSM-OEF of the REPs’ brain is higher than that of HS, which indicates that QSM-OEF is associated with disease activity.     

Expression Profiling and Structural Characterization of MicroRNAs in Adipose Tissues of Hibernating Ground Squirrels

Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adipose tissue（WAT） during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six mi RNAs including let-7a, let-7b, mi R-107, mi R-150, mi R-222 and mi R-31 was significantly downregulated in WAT（P 〈 0.05）, which was 16%–54% of euthermic non-torpid control squirrels,whereas expression of three mi RNAs including mi R-143, mi R-200 a and mi R-519 d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more mi RNAs was downregulated in BAT during torpor. We detected reduced expression of 6 mi RNAs including mi R-103 a, mi R-107, mi R-125 b, mi R-21, mi R-221 and mi R-31（48%–70% of control）, while only expression of mi R-138 was significantly upregulated（2.91 ± 0.8-fold of the control, P 〈 0.05）. Interestingly,mi RNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas mi RNAs with altered expression in BAT during torpor were linked to mitochondrial b-oxidation. mi RPath target prediction analysis showed that mi RNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase（MAPK） signaling, while the mi RNAs upregulated in WAT were linked to transforming growth factor b（TGFb） signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-mi RNAs for the mi RNAs used in this study, suggesting no structure-influenced changes in pre-mi RNA processing efficiency in the squirrel. As well, the expression of mi RNA processingenzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of mi RNA expression in adipose tissues may be linked     

Metabolic response to cooling temperatures in chicken embryos and hatchlings after cold incubation

We asked to what extent cold exposure during embryonic growth, and the accompanying hypometabolism, may interfere with the normal development of thermogenesis. White Leghorn chicken eggs were incubated in control conditions (38 degrees C) or at 36 or 35 degrees C. Embryos incubated at a lower temperature (34 degrees C) failed to hatch. The cold-incubated embryos had lower oxygen consumption (VO2) and body weight (W) throughout incubation, and hatching was delayed by about, respectively, 1 and 2 days. The W-VO2 relationship of the cold-incubated embryos was as in controls, indicating that cold-induced hypometabolism was at the expense of the growth, not the maintenance, component of VO2. At embryonic day E11, the metabolic response to changes in ambient temperature (T) over the 30-39 degrees C range was typically poikilothermic, with Q10 = 1.8-1.9, and similar among all sets of embryos. Toward the end of incubation (E20), the thermogenic responses of the cold-incubated embryos were significantly lower than in controls. This difference occurred also in the few-hour old hatchlings (H1), even though, at this time, W was similar among groups. Exposure to cold during only the last 3 days of incubation (from E18 to H1), i.e. during the developmental onset of the endothermic mechanisms, did not lower the thermogenic capacity of the hatchlings. In conclusion, sustained cold-induced hypometabolism throughout incubation blunted the rate of embryonic growth and the development of thermogenesis. This latter phenomenon could be an example of epigenetic regulation, i.e. of environmental factors exerting a long-term effect on gene expression.     

The protective effects of hypoxia-induced hypometabolism in the Nautilus

Specimens of Nautilus pompilius were trapped at depths of 225–300 m off the sunken barrier reef south-east of Port Moresby, Papua New Guinea. Animals transported to the Motupore Island laboratory were acclimated to normal habitat temperatures of 18 °C and then cannulated for arterial and venous blood sampling. When animals were forced to undergo a period of progressive hypoxia eventually to encounter ambient partial pressure of oxygen (PO₂) levels of ∼10 mmHg (and corresponding arterial PO₂'s of ∼5 mmHg), they responded by lowering their aerobic metabolic rates to 5–10% of those seen in resting normoxic animals. Coincident with this profound metabolic suppression was an overall decrease in activity, with brief periods of jet propulsion punctuating long periods of rest. Below ambient PO₂ levels of 30–40 mmHg, ventilatory movements became highly periodic and at the lowest PO₂ levels encountered, ventilation occasionally ceased altogether. Cardiac output estimated by the Fick equation decreased during progressive hypoxia by as much as 75–80%, and in the deepest hypometabolic states heart rates slowed to one to two cycles of very low amplitude per minute. By the end of 500 min exposure to ambient PO₂ levels of 10 mmHg or less, the anaerobic end products octopine and succinate had increased significantly in adductor muscle and heart, respectively. Increased concentrations of octopine in adductor muscle apparently contributed to a small intracellular acidosis and to the development of a combined respiratory and metabolic acidosis in the extracellular compartment. On the other hand, increases in succinate in heart muscle occurred in the absence of any change in cardiac pHi. Taken together, we estimate that these anaerobic end products would make up less than 2% of the energy deficit arising from the decrease in aerobic metabolism. Thus, metabolic suppression is combined with a massive downregulation of systemic O₂ delivery to match metabolic supply to demand. Accepted: 26 January 2000