Heme oxygenase‐1: a new drug target in oxidative tissue injuries in critically ill conditions

Oxidative stresses associated with ischemia/reperfusion, neutrophil activation, and anesthesia with certain volatile agents, etc., are thought to play an important role in the development of acute organ failure in critical illnesses, such as acute lung injury, acute coronary artery insufficiency, acute liver failure, acute renal failure, and multiple organ dysfunction syndrome. Such oxidative stressors provoke a set of cellular responses, particularly those that participate in the defense against tissue injuries. Free heme, which can be rapidly released from hemeproteins, may constitute a major threat in the oxidant stress because it catalyzes the formation of reactive oxygen species. To counteract such insults, cells respond by inducing the 33‐kDa heat shock protein, heme oxygenase (HO)‐1, the rate‐limiting enzyme in heme degradation. Induced HO‐1 as such removes free heme by an enzymatic process. In addition, HO‐1 induction itself confers protection to tissues from further oxidative injuries. In contrast, the abrogation of HO‐1 induction, or chemical ablation of HO activity abolishes the beneficial effect of HO‐1, and results in the aggravation of tissue injuries. In this article, we review recent advances in the essential role of HO‐1 in tissue protection in various models of experimental oxidative tissue injuries as well as in human disorders, which is related to critically ill conditions, with special emphasis on the role of its induction in tissue defense and its potential therapeutic implications. Drug Dev. Res. 67:130–153, 2006. © 2006 Wiley‐Liss, Inc.     

Artificial plaque removal with Carisolv system: a clinical approach

In the present study, removal of artifcial plaque in pits and fissures with the Carisolv system was compared with that of conventional bristle brush methoda in vitro. The results indicate that in the dental clinic, complete plaque removal with the Carisolv is possible, and in addition to acid etching, treated cavity was almost free of debris which might increase sealant retention.     

Cellular roles in physiological root resorption of deciduous teeth in the cat

This study has attempted to assess the importance of mesenchymal cells, fibroblasts, cementoblasts, and mononuclear phagocytes (i.e., macrophages) in physiological root resorption of feline deciduous teeth. Deciduous incisors of three- to six-month-old kittens undergoing root resorption were investigated by means of electron microscopy. In an early phase of root resorption, the resorption organ consisted of many fibroblasts and relatively few macrophages and odontoclasts, the last with a wide, clear zone and narrow, immature, ruffled border. In the active phase of root resorption, the resorption organ contained many odontoclasts with a well-developed ruffled border and a reduced clear zone, cementoblasts, fibroblasts, macrophages, neutrophils, and many blood vessels. Cementoblasts were present usually on the resorbing dentin surface adjacent to odontoclasts and, in many cases, these cells communicated with each other via gap junctions. Cementoblasts frequently extended broad cell processes with secretion granules and with phagosomes containing collagen fibrils into the dentinal tubules exposed to resorption lacunae. Some macrophages exhibiting a clear zone-like structure also appeared on resorbing dentin surfaces. In the resting phase of root resorption, the dentin surface was covered mostly with cementoblasts resembling bone lining cells. There was an occasional macrophage, but no odontoclasts were observed during this phase. During removal of the periodontal ligament concomitant with root resorption, many fibroblasts phagocytosed mature collagen fibrils, as well as amorphous fluffy material. These results suggest that these mesenchymal cells, as well as odontoclasts, are essential for the cellular removal of dental hard and soft tissues during shedding of feline deciduous teeth.     

Non-Gaussian Methods for Causal Structure Learning

Prevention Science - Causal structure learning is one of the most exciting new topics in the fields of machine learning and statistics. In many empirical sciences including prevention science, the...     

Detection of Intestinal Pneumatosis Location by Following Hyperechoic Foci in the Portal Vein Along Its Branches With Real‐time Ultrasound

Portal venous gas is occasionally encountered in children with intestinal pneumatosis, identified on real‐time ultrasound imaging as hyperechoic foci with quick movement. The origin of the portal venous gas can be identified by following the hyperechoic foci along the branches of the portal vein, providing an estimate of the location of intestinal pneumatosis. This approach may be useful for predicting the patient's prognosis. Our report describes 2 cases of portal venous gas while estimating the area of intestinal pneumatosis, which were evaluated with real‐time ultrasound.     

Robust arterial transit time and cerebral blood flow estimation using combined acquisition of Hadamard‐encoded multi‐delay and long‐labeled long‐delay pseudo‐continuous arterial spin labeling: a simulation and in vivo study

Arterial transit time (ATT) prolongation causes an error of cerebral blood flow (CBF) measurement during arterial spin labeling (ASL). To improve the accuracy of ATT and CBF in patients with prolonged ATT, we propose a robust ATT and CBF estimation method for clinical practice. The proposed method consists of a three‐delay Hadamard‐encoded pseudo‐continuous ASL (H‐pCASL) with an additional‐encoding and single‐delay with long‐labeled long‐delay (1dLLLD) acquisition. The additional‐encoding allows for the reconstruction of a single‐delay image with long‐labeled short‐delay (1dLLSD) in addition to the normal Hadamard sub‐bolus images. Five different images (normal Hadamard 3 delay, 1dLLSD, 1dLLLD) were reconstructed to calculate ATT and CBF. A Monte Carlo simulation and an in vivo study were performed to access the accuracy of the proposed method in comparison to normal 7‐delay (7d) H‐pCASL with equally divided sub‐bolus labeling duration (LD). The simulation showed that the accuracy of CBF is strongly affected by ATT. It was also demonstrated that underestimation of ATT and CBF by 7d H‐pCASL was higher with longer ATT than with the proposed method. Consistent with the simulation, the 7d H‐pCASL significantly underestimated the ATT compared to that of the proposed method. This underestimation was evident in the distal anterior cerebral artery (ACA; P = 0.0394) and the distal posterior cerebral artery (PCA; 2 P = 0.0255). Similar to the ATT, the CBF was underestimated with 7d H‐pCASL in the distal ACA (P = 0.0099), distal middle cerebral artery (P = 0.0109), and distal PCA (P = 0.0319) compared to the proposed method. Improving the SNR of each delay image (even though the number of delays is small) is crucial for ATT estimation. This is opposed to acquiring many delays with short LD. The proposed method confers accurate ATT and CBF estimation within a practical acquisition time in a clinical setting.