Assessing the safety and feasibility of chronic delivery of compounds to the brain using convection-enhanced delivery (CED) is important for the further development of this important therapeutic ...technology. The objective of this study was to follow and model the distribution of a compound delivered by CED into the putamen of rhesus monkeys.
The authors sequentially implanted catheters into 4 sites spanning the left and right putamen in each of 6 rhesus monkeys. The catheters were connected to implanted pumps, which were programmed to deliver a 5-mM solution of the MRI contrast agent Gd-DTPA at 0.1 μl/minute for 7 days and 0.3 μl/minute for an additional 7 days. The animals were followed for 28 days per implant cycle during which they were periodically examined with MRI.
All animals survived the 4 surgeries with no deficits in behavior. Compared with acute infusion, the volume of distribution (Vd) increased 2-fold with 7 days of chronic infusion. Increasing the flow rate 3-fold over the next week increased the Vd an additional 3-fold. Following withdrawal of the compound, the half-life of Gd-DTPA in the brain was estimated as 3.1 days based on first-order pharmacokinetics. Histological assessment of the brain showed minimal tissue damage limited to the insertion site.
These results demonstrate several important features in the development of a chronically implanted pump and catheter system: 1) the ability to place catheters accurately in a predetermined target; 2) the ability to deliver compounds in a chronic fashion to the putamen; and 3) the use of MRI and MR visible tracers to follow the evolution of the infusion volume over time.
Autophagy is a catabolic process that functions in recycling and degrading cellular proteins, and is also induced as an adaptive response to the increased metabolic demand upon nutrient starvation. ...However, the prosurvival role of autophagy in response to metabolic stress due to deprivation of glutamine, the most abundant nutrient for mammalian cells, is not well understood. Here, we demonstrated that when extracellular glutamine was withdrawn, autophagy provided cells with sub-mM concentrations of glutamine, which played a critical role in fostering cell metabolism. Moreover, we uncovered a previously unknown connection between metabolic responses to ATG5 deficiency and glutamine deprivation, and revealed that WT and atg5
−/−
MEFs utilized both common and distinct metabolic pathways over time during glutamine deprivation. Although the early response of WT MEFs to glutamine deficiency was similar in many respects to the baseline metabolism of atg5
−/−
MEFs, there was a concomitant decrease in the levels of essential amino acids and branched chain amino acid catabolites in WT MEFs after 6 h of glutamine withdrawal that distinguished them from the atg5
−/−
MEFs. Metabolomic profiling, oxygen consumption and pathway focused quantitative RT-PCR analyses revealed that autophagy and glutamine utilization were reciprocally regulated to couple metabolic and transcriptional reprogramming. These findings provide key insights into the critical prosurvival role of autophagy in maintaining mitochondrial oxidative phosphorylation and cell growth during metabolic stress caused by glutamine deprivation.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Huntington's disease is an autosomal dominant neurodegenerative disease caused by a toxic gain of function mutation in the huntingtin gene (Htt). Silencing of Htt with RNA interference using direct ...CNS delivery in rodent models of Huntington's disease has been shown to reduce pathology and promote neuronal recovery. A key translational step for this approach is extension to the larger non-human primate brain, achieving sufficient distribution of small interfering RNA targeting Htt (siHtt) and levels of Htt suppression that may have therapeutic benefit. We evaluated the potential for convection enhanced delivery (CED) of siHtt to provide widespread and robust suppression of Htt in nonhuman primates. siHtt was infused continuously for 7 or 28days into the nonhuman primate putamen to analyze effects of infusion rate and drug concentration on the volume of effective suppression. Distribution of radiolabeled siHtt and Htt suppression were quantified by autoradiography and PCR, respectively, in tissue punches. Histopathology was evaluated and Htt suppression was also visualized in animals treated for 28days. Seven days of CED led to widespread distribution of siHtt and significant Htt silencing throughout the nonhuman primate striatum in an infusion rate and dose dependent manner. Htt suppression at therapeutic dose levels was well tolerated by the brain. A model developed from these results predicts that continuous CED of siHtt can achieve significant coverage of the striatum of Huntington's disease patients. These findings suggest that this approach may provide an important therapeutic strategy for treating Huntington's disease.
► Chronic convection enhanced delivery of siRNA targeting Huntingtin in primate brain. ► Widespread drug distribution results in Huntingtin lowering throughout striatum. ► Empirical model of data enables scaling of siRNA delivery. ► Potential as key disease-modifying therapeutic approach for Huntington's disease.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
One possible treatment for Huntington's disease involves direct infusion of a small, interfering RNA (siRNA) designed to reduce huntingtin expression into brain tissue from a chronically implanted ...programmable pump. Here, we studied the suppression of huntingtin mRNA achievable with short infusion times, and investigated how long suppression may persist after infusion ceases. Rhesus monkeys received 3 days of infusion of Magnevist into the putamen to confirm catheter patency and fluid distribution. After a 1-week washout period, monkeys received radiolabeled siRNA targeting huntingtin. After 1 or 3 days of siRNA delivery, monkeys were either terminated, or their pumps were shut off and they were terminated 10 or 24 days later. Results indicate that the onset of huntingtin mRNA suppression in the rhesus putamen occurs rapidly, achieving a plateau throughout the putamen within 4 days. Conversely, loss of huntingtin suppression progresses slowly, persisting an estimated 27–39 days in the putamen and surrounding white matter. These findings indicate the rapid onset and durability of siRNA-mediated target gene suppression observed in other organs also occurs in the brain, and support the use of episodic delivery of siRNA into the brain for treatment of Huntington's disease and possibly other neurodegenerative diseases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
FEM software was used to determine the feasibility of characterizing various types of atherosclerotic lesions in vivo. This was accomplished by simulating two electrodes as being attached to an ...angioplasty balloon in the coronary artery. The electrodes on the "balloon" touched and measured the simulated complex impedance of type III, IV, and Va and Vb lesions, as defined by the American Heart Association (AHA). Additionally, the effect of changes in morphology on the complex impedance was determined for type Va and Vb lesions. The simulations showed that the layer closest to the electrodes had the most significant effect on the measured complex impedance. As a consequence of these simulations, it appears plausible that electrodes could be placed in vivo to determine the characteristics and type of a given atherosclerotic lesion.
Abstract
The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia ...detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer’s ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient’s clinical status and desired outcome via a shared clinical decision-making process.
There is a known association between obstructive sleep apnea (OSA) and atrial fibrillation (AF); however, how OSA affects the atrial myocardium is not well described.
To determine whether patients ...with OSA have an abnormal atrial substrate.
Forty patients undergoing ablation of paroxysmal AF and in sinus rhythm (20 with OSA apnea-hypopnea index ≥ 15 and 20 reference patients with no OSA apnea-hypopnea index < 15 by polysomnography) were studied. Multipolar catheters were positioned at the lateral right atrium (RA), coronary sinus, crista terminalis, and RA septum to determine the effective refractory period at 5 sites, conduction time along linear catheters at the RA and the coronary sinus, conduction at the crista terminalis, and sinus node function (corrected sinus node recovery time). Biatrial electroanatomic maps were created to determine the voltage, conduction, and distribution of complex electrograms (duration ≥ 50 ms).
The groups had no differences in the prevalence of established risk factors for AF. Patients with OSA had the following compared with those without OSA: no difference in effective refractory period (P = .9), prolonged conduction times along the coronary sinus and RA (P = .02), greater number (P = .003) and duration (P = .03) of complex electrograms along the crista terminalis, longer P-wave duration (P = .01), longer corrected sinus node recovery time (P = .02), lower atrial voltage (RA, P <.001; left atrium, P <.001), slower atrial conduction velocity (RA, P = .001; left atrium, P = .02), and more widespread complex electrograms in both atria (RA, P = .02; left atrium, P = .01).
OSA is associated with significant atrial remodeling characterized by atrial enlargement, reduction in voltage, site-specific and widespread conduction abnormalities, and longer sinus node recovery. These features may in part explain the association between OSA and AF.
Background Several single-institution series have demonstrated that compared with open thoracotomy, video-assisted thoracoscopic lobectomy may be associated with fewer postoperative complications. In ...the absence of randomized trials, we queried the Society of Thoracic Surgeons database to compare postoperative mortality and morbidity following open and video-assisted thoracoscopic lobectomy. A propensity-matched analysis using a large national database may enable a more comprehensive comparison of postoperative outcomes. Methods All patients having lobectomy as the primary procedure via thoracoscopy or thoracotomy were identified in the Society of Thoracic Surgeons database from 2002 to 2007. After exclusions, 6323 patients were identified: 5042 having thoracotomy, 1281 having thoracoscopy. A propensity analysis was performed, incorporating preoperative variables, and the incidence of postoperative complications was compared. Results Matching based on propensity scores produced 1281 patients in each group for analysis of postoperative outcomes. After video-assisted thoracoscopic lobectomy, 945 patients (73.8%) had no complications, compared with 847 patients (65.3%) who had lobectomy via thoracotomy ( P < .0001). Compared with open lobectomy, video-assisted thoracoscopic lobectomy was associated with a lower incidence of arrhythmias n = 93 (7.3%) vs 147 (11.5%); P = .0004, reintubation n = 18 (1.4%) vs 40 (3.1%); P = .0046, and blood transfusion n = 31 (2.4%) vs n = 60 (4.7%); P = .0028, as well as a shorter length of stay (4.0 vs 6.0 days; P < .0001) and chest tube duration (3.0 vs 4.0 days; P < .0001). There was no difference in operative mortality between the 2 groups. Conclusions Video-assisted thoracoscopic lobectomy is associated with a lower incidence of complications compared with lobectomy via thoracotomy. For appropriate candidates, video-assisted thoracoscopic lobectomy may be the preferred strategy for appropriately selected patients with lung cancer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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