Preferential Inhibition of Frontal-to-Parietal Feedback Connectivity Is a Neurophysiologic Correlate of General Anesthesia in Surgical Patients

BACKGROUND: The precise mechanism and optimal measure of anesthetic-induced unconsciousness has yet to be elucidated. Preferential inhibition of feedback connectivity from frontal to parietal brain networks is one potential neurophysiologic correlate, but has only been demonstrated in animals or under limited conditions in healthy volunteers. METHODS AND FINDINGS: We recruited eighteen patients presenting for surgery under general anesthesia; electroencephalography of the frontal and parietal regions was acquired during (i) baseline consciousness, (ii) anesthetic induction with propofol or sevoflurane, (iii) general anesthesia, (iv) recovery of consciousness, and (v) post-recovery states. We used two measures of effective connectivity, evolutional map approach and symbolic transfer entropy, to analyze causal interactions of the frontal and parietal regions. The dominant feedback connectivity of the baseline conscious state was inhibited after anesthetic induction and during general anesthesia, resulting in reduced asymmetry of feedback and feedforward connections in the frontoparietal network. Dominant feedback connectivity returned when patients recovered from anesthesia. Both analytic techniques and both classes of anesthetics demonstrated similar results in this heterogeneous population of surgical patients. CONCLUSIONS: The disruption of dominant feedback connectivity in the frontoparietal network is a common neurophysiologic correlate of general anesthesia across two anesthetic classes and two analytic measures. This study represents a key translational step from the underlying cognitive neuroscience of consciousness to more sophisticated monitoring of anesthetic effects in human surgical patients

Selective laser ablation of metal thin films using ultrashort pulses

Selective thin-film removal is needed in many microfabrication processes such as 3-D patterning of optoelectronic devices and localized repairing of integrated circuits. Various wet or dry etching methods are available, but laser machining is a tool of green manufacturing as it can remove thin films by ablation without use of toxic chemicals. However, laser ablation causes thermal damage on neighboring patterns and underneath substrates, hindering its extensive use with high precision and integrity. Here, using ultrashort laser pulses of sub-picosecond duration, we demonstrate an ultrafast mechanism of laser ablation that leads to selective removal of a thin metal film with minimal damage on the substrate. The ultrafast laser ablation is accomplished with the insertion of a transition metal interlayer that offers high electron-phonon coupling to trigger vaporization in a picosecond timescale. This contained form of heat transfer permits lifting off the metal thin-film layer while blocking heat conduction to the substrate. Our ultrafast scheme of selective thin film removal is analytically validated using a two-temperature model of heat transfer between electrons and phonons in material. Further, experimental verification is made using 0.2 ps laser pulses by micropatterning metal films for various applications.Comment: 19 pages, 4 figures. This manuscript has been submitted to International Journal of Precision Engineering and Manufacturing-Green Technolog

Root and bone response to the proximity of a mini-implant under orthodontic loading

Objective: To determine the histological reaction of the root and bone as a mini-implant approaches the root. Materials and Methods: Two kinds of mini-implants were inserted into the buccal alveolar bone of 4 beagles (2 males and 2 females). The specimens were classified as the near-root group, the PDL contact group, the root contact group, and the root perforation group. Cementum resorption, dentin resorption, cementum repair, cementum growth, ankylosis, root cracking, and root fracture were assessed as the implant neared the root. Results: The incidence of root resorption increased when the mini-implant was less than 0.6 mm from the root in the near-root group and PDL contact group. Root cracking and root fracture occurred in the root contact group and root perforation group. Bone resorption and ankylosis were observed in some specimens. However, some specimens of the PDL contact group and root contact group had cementum growth or little root resorption despite proximity to the root. In the root perforation group, root resorption and ankylosis occurred on the side opposite the insertion. Conclusions: There is a risk of root contact and severe tissue damage from a thick mini-implant and the drilling procedure, either of which can induce root resorption or ankylosis. Use of smaller mini-implants may reduce root contact and tissue damage. However, the small mini-implant may need enhancement of its stability.This study was supported by grant number 11-2009-013 from the SNUBH Research Fund

Non-Functional Parathyroid Adenoma Presenting as a Massive Cervical Hematoma: A Case Report

Parathyroid adenoma usually manifests with symptoms related to hypercalcemia, such as urinary stone and bone fracture. It may also present with asymptomatic hypercalcemia. However, spontaneous cervical hematoma may occur very rarely as a result of extracapsular hemorrhage of a cervical parathyroid adenoma causing acute painful cervical swelling, bruising, dyspnea, hoarseness and dysphagia. We report a 44-year-old woman who manifested as a spontaneous cervical hematoma without any clinical evidence of hyperparathyroidism

Chemical Stability of Conductive Ceramic Anodes in LiCl–Li2O Molten Salt for Electrolytic Reduction in Pyroprocessing

AbstractConductive ceramics are being developed to replace current Pt anodes in the electrolytic reduction of spent oxide fuels in pyroprocessing. While several conductive ceramics have shown promising electrochemical properties in small-scale experiments, their long-term stabilities have not yet been investigated. In this study, the chemical stability of conductive La0.33Sr0.67MnO3 in LiCl–Li2O molten salt at 650°C was investigated to examine its feasibility as an anode material. Dissolution of Sr at the anode surface led to structural collapse, thereby indicating that the lifetime of the La0.33Sr0.67MnO3 anode is limited. The dissolution rate of Sr is likely to be influenced by the local environment around Sr in the perovskite framework

In vivo and in vitro safety evaluation of fermented Citrus sunki peel extract: acute and 90-day repeated oral toxicity studies with genotoxicity assessment

Abstract Background Citrus sunki Hort. ex Tanaka peel has been traditionally used as an ingredient in folk medicine due to its therapeutic effects on promotion of splenic health and diuresis as well as relief of gastrointestinal symptoms. Although a growing interest in health-promoting natural products and the development of highly concentrated products have facilitated consumption of C. sunki peel, its safety assessment has not been explored, posing a potential health risk. In this study, we carried out a series of systemic and genetic toxicity tests on fermented C. sunki peel extract (FCPE) to provide the essential information required for safe use in human. Methods We conducted acute and 90-day repeated oral toxicity studies in Sprague-Dawley rats to evaluate systemic toxicity, and three genotoxicity assays to measure bacterial mutation reversion, cellular chromosome aberration and in vivo micronucleus formation. Results Single oral administration of FCPE did not cause any clinical signs and lethality in all animals, establishing LD50 to be over 2000 mg/kg BW. Repeated administration of up to 2000 mg/kg BW FCPE for 90 days revealed no test substance-related toxicity as demonstrated in analysis of body weight gain, food/water intake, blood, serum biochemistry, organweight and histopathology, collectively determining that the no-observable-adverse-effect-level of FCPE is over 2000 mg/kg BW. In addition, we detected no mutagenicity and clastogenicity in FCPE at 5000 μg/plate for the in vitro assays and 2000 mg/kg BW for the in vivo micronucleus test. Conclusion FCPE did not cause systemic and genetic toxicity in our model systems at the tested dose levels. These results suggest a guideline for safe consumption of C. sunki peel in human