It has been reported that ischemic preconditioning of the heart or brain has a possible relevance to heat shock protein (HSP). It is still unknown, however, whether HSP induced by means of ischemic preconditioning of the liver is a direct factor in the acquisition of tolerance to succeeding ischemia-reperfusion injury. In the present study we used ischemic preconditioning of the liver to verify the effects of induced HSP72 in the liver on the subsequent longer warm ischemia and reperfusion. Rats preconditioned with short-term (15-minute) ischemia were compared with rats preconditioned by heat exposure or with control rats. After a 48-hour recovery from the sublethal stress for preconditioning, all rats were exposed to longer (30-minute) warm ischemia and reperfusion. Forty-eight hours after ischemic preconditioning, HSP72 was clearly induced in the liver, as well as in the liver preconditioned with heat shock, but not in the kidney or heart. This ischemic preconditioning also attenuated the liver damage in the subsequent ischemia-reperfusion injury, improving the restoration of hepatic function during reperfusion and resulting in higher postischemic rat survival. According to the proposed model of tolerance acquisition for ischemia-reperfusion injury by stress preconditioning, these observations support the speculation that the induced HSP72 plays some beneficial role in this protection mechanism.

No abstract

Cryopreserved porcine hepatocytes are a ready source of metabolic function for use in a bioartificial liver (BAL). However, cryopreservation is associated with a loss of hepatocyte viability. The mechanism of cell death during cryopreservation is incompletely understood, but may involve apoptosis through caspase activation. This study evaluates the cytoprotective effect of a global caspase inhibitor, benzyloxycarbonyl-Val-Ala-DL-Asp-fluoromethylketone (ZVADfmk) during cryopreservation of porcine hepatocytes. Freshly isolated porcine hepatocytes (viability, 97.4% ؎ 0.9%) were cryopreserved in 60 mol/L ZVAD-fmk (؉ZVAD group) or without ZVAD-fmk (؊ZVAD group) for 24 to 72 hours. Apoptotic and necrotic death were both observed after thawing and after 24 hours of culture. Caspase 3-like activity was significantly reduced by ZVADfmk, and was associated with improved viability and reduced apoptotic death of porcine hepatocytes after cryopreservation. Mitochondrial membrane potential (MMP) was increased in cultures of porcine hepatocytes that were cryopreserved in ZVAD-fmk. These results demonstrate the following: 1) Caspase 3-like protease activation and apoptosis occurs in porcine hepatocytes during cryopreservation; and 2) mitochondrial injury in this process is reduced by caspase inhibition. (HEPATOLOGY 2001;33:1432-1440.)A number of liver-assist devices have been developed, including the extracorporeal use of isolated mammalian hepatocytes to provide metabolic function in a bioartificial liver (BAL). 1,2 Criteria for successful application of a BAL include bridging patients to liver transplantation, reduction of intracranial hypertension and cerebral edema, and avoidance of liver transplantation in cases of reversible hepatic failure. 3-5 To achieve these goals, hepatocytes in the BAL provide metabolic functions to the patient in liver failure. The extent to which these goals can be achieved is dependent on several variables, including the number of viable and metabolically active hepatocytes in the device. 6 Unfortunately, hepatocyte viability declines over time following isolation, and this decline limits the effectiveness and duration of BAL therapy. Cryopreservation, which allows cells to be used weeks and months after isolation, may also contribute to premature cell death. 7,8 Several BAL systems have been designed to maintain hepatocyte viability ex vivo. One such BAL system involves the entrapment of hepatocytes in cylindrical collagen gels located in the fibers of a hollow fiber bioreactor. 9,10 An in vitro model of this BAL system using gel-entrapped hepatocytes has been developed for static culture experimentation, such as the study of mechanisms of hepatocyte death. 11 The in vitro model avoids the expenses of largescale testing, and multiple experiments can be performed simultaneously. Potential immune interactions, present with in vivo models of BAL testing, are also avoided with in vitro testing.Our recent work has shown that cell death of freshly isolated hepatocytes occurs, in part, by apoptosis. 12...

eft atrial (LA) enlargement is associated with cardiovascular disease and is a risk factor for atrial fibrillation, stroke, and death. 1,2 However, LA antero-posterior dimensions have well-known limitations for indicators of chamber size, for example, the left ventricular (LV) dimension is a poor indicator of LV volume. Two-dimensional (D) echocardiography-derived LA volume has been shown to provide a more accurate assessment of LA size than the M-mode LA dimension. [3][4][5][6][7][8] Recent studies demonstrated that the LA volume was more strongly associated with the future development of atrial fibrillation than LA dimension. 9,10 The LA volume was also strongly associated with the prognosis of patients with acute myocardial infarction 11 and dilated cardiomyopathy. 12 Methods to calculate LA volume have been described, [3][4][5][6] but the distribution of LA volume in normal Japanese subjects who do not have cardiovascular disease has not been reported. Our objective was to provide reference ranges of the LA volume in healthy Japanese adults. Methods Study SubjectsEligible subjects were adults ≥20 years of age who were referred for outpatient transthoracic echocardiographic examination because of non-specific chest symptoms. All subjects had sinus rhythm, and no history of atrial arrhyth-