Kazuo To

Down-regulation of AMP-activated protein kinase by calorie restriction in rat liver

AMP-activated protein kinase (AMPK) may act as a key enzyme for metabolic adaptation to calorie restriction (CR) or reduced growth hormone (GH)-insulin-like growth factor (IGF)-1 signaling, an experimental intervention for lifespan extension in animals. We investigated the protein levels of AMPKalpha and a downstream enzyme, acetyl-CoA carboxylase (ACC), by immunoblotting of liver and quadriceps femoris muscle (QFM) extracts from 6-month-old wild-type (W) and GH-suppressed transgenic (Tg) Wistar rats fed ad libitum (AL) or 30% CR diets from 6weeks of age. A modified alternate-day feeding regimen for CR yielded a fed-fasted cycle in CR rats, and therefore the effects of overnight fasting in W-AL rats were also evaluated. CR decreased threonine-172-phosphorylated AMPKalpha (p-AMPKalpha; an activated form) levels in the liver, whereas the CR-fed-fasted cycle or overnight fasting did not significantly affect the p-AMPKalpha level. In the QFM, the p-AMPKalpha level was slightly elevated in the CR-fasted phase, but greatly increased in the AL-fasted phase. Suppression of GH did not affect the p-AMPKalpha level. The phosphorylated-ACC levels did not alter in parallel with the p-AMPKalpha level, particularly in the liver. The present results suggest that CR down-regulates the AMPK activity in the liver on a long-term basis.

A transgenic dwarf rat model as a tool for the study of calorie restriction and aging

We have previously reported a long-lived transgenic dwarf rat model, in which the growth hormone (GH)-insulin like growth factor (IGF)-1 axis was selectively suppressed by overexpression of antisense GH transgene. Rats heterozygous for the transgene (tg/-) manifest phenotypes similar to those in calorie-restricted (CR) rats. To further characterize the transgenic rat in comparison with CR rats, the present study evaluated glucose and insulin tolerance in tg/- and control Wistar (-/-) rats at 6-9 months of age. Rats were fed ad libitum (AL) or 30% CR from 6 weeks of age. In CR rats, glucose disposal after glucose load was facilitated without any significant surge of serum insulin, and insulin tolerance test also indicated increased insulin sensitivity. In transgenic rats, similar findings were observed after glucose and insulin load, and CR in tg/- rats further facilitated glucose disposal during glucose and insulin tolerance tests. These findings suggest the presence of both common and separate mechanisms regulating the glucose-insulin system between CR and the reduced GH-IGF-1 axis paradigms. The transgenic rat model is, therefore, a useful one for studies of CR and aging.

Short-term outcomes of laparoscopic surgery for colorectal cancer in oldest-old patients.

Background/Aims: Oldest-old patients generally have several comorbidities, and laparoscopic-assisted colectomy (LAC) has not been performed on these patients. However, the surgical technique of LAC has improved, and its indications have been extended. The aim of this study was to evaluate the safety and effectiveness of LAC for patients over 85 years old. Methods: Fifty-eight patients over 85 years old who underwent colectomy were retrospectively analyzed. The patients were divided into two groups (LAC group n = 15; open surgery group (Open group) n = 43), and clinicopathological features, surgical characteristics, and outcomes were compared. Results: There were no significant differences in clinical background characteristics between the groups. The LAC group had longer operation time and greater lymph node dissection (both p < 0.01). Postoperatively, the use of analgesics (p = 0.01) was less and the start of oral liquid intake (p = 0.03) was faster in the LAC group. Postoperative complications occurred in 3 patients (20%) in the LAC group and 13 patients (30%) in the Open group (p = 0.66); delirium (n = 6) and sub-ileus (n = 4) developed only in the Open group. Conclusion: After LAC, elderly patients tended to have less postoperative pain and started oral liquid intake earlier. LAC can be safe and effective, preventing postoperative complications that occur specifically in oldest-old patients.

Expression of DNase gamma during Fas-independent apoptotic DNA fragmentation in rodent hepatocytes

Endonuclease-induced DNA fragmentation is a hallmark of apoptosis. DNase gamma (DNase γ) was recently identified as one of the endonucleases responsible for apoptotic DNA fragmentation. In this study, immunohistochemistry for DNase γ was performed on paraffin sections of rodent liver in well-defined models of hepatocyte apoptosis induced by Fas antibody (Fas) or cycloheximide (CHX), and necrosis induced by lipopolysaccharide (LPS) or carbon tetrachloride (CCl4). DNase γ immunoreactivity was compared with TdT-mediated dUTP nick-end labeling (TUNEL) reactivity. Our results showed TUNEL reactivity in both apoptotic and necrotic hepatocytes. DNase γ immunoreactivity was not detected during LPS-induced or CCl4-induced hepatocyte necrosis. In contrast, it was evident during CHX-induced, but not Fas-induced, apoptotic DNA fragmentation. These findings suggest that DNase γ plays an important role in Fas-independent apoptotic DNA fragmentation in hepatocytes.

Usefulness of evaluating hepatic elasticity using artificial acoustic radiation force ultrasonography before hepatectomy

To evaluate hepatic fibrosis and tumor diagnosis preoperatively, we investigated the elasticity calculated by the new parameter of ultrasonography, acoustic radiation force impulse (ARFI).

Involvement of DNase γ in apoptotic DNA fragmentation in histiocytic necrotizing lymphadenitis

DNA fragmentation induced by endonucleases is a hallmark of apoptotic process. One of the endonucleases responsible for apoptotic DNA fragmentation has been identified as DNase γ. It has been suggested that massive nuclear debris observed in histiocytic necrotizing lymphadenitis (HNL, Kikuchi disease) results mainly from apoptosis of T-lymphocytes rather than necrosis. To identify the role of DNase γ in apoptotic foci of HNL paraffin embedded tissue sections of HNL and lymphadenopathy with hyperplastic germinal centers and paracortex in the neck lymph nodes were immunohistochemically stained for DNase γ and the results compared with the reactivity of TdT-mediated dUTP nick end labeling (TUNEL). Immunoreactivity for DNase γ was detected in fragmented and condensed nuclei found abundantly in HNL as well as TUNEL reactivity. Moreover, the ratio of DNase γ immunoreactivity to TUNEL reactivity, which represents probability of apoptosis relevant to DNase γ, was higher in foci of nuclear debris in HNL than in the hyperplastic paracortex in lymphadenopathy including T-cell apoptosis. Our findings suggest that apoptosis detected in HNL depends more specifically upon DNase γ than apoptosis in the hyperplastic paracortex of lymphadenopathy, and that the dysregulation of DNase γ activation is involved in apoptosis in HNL

Prognostic influence of the liver hanging maneuver for patients with hepatobiliary malignancies who underwent hepatic resections

BACKGROUND Prognostic influences of hepatic transection by an anterior approach using the liver hanging maneuver (LHM) has not been fully clarified. METHODS We examined 233 patients who underwent major hepatectomy with the LHM (n = 75; hepatocellular carcinoma (HCC) in 35, colorectal liver metastasis (CLM) in 10, intrahepatic cholangiocarcinoma (ICC) in 14 and perihilar bile duct carcinoma (BDC) in 16) or without it (n = 158; HCC in 78, CLM in 21, ICC in 31 and BDC in 28). RESULTS In HCC patients, cancer-positive margin rate, blood loss, transection time and prevalence of posthepatectomy ascites in the LHM group were significantly lower than those in the non-LHM group (p < 0.05). In CLM, transection time in the LHM group was significantly lower than that in the non-LHM group (p < 0.05). In BDC patients, amount of blood loss, transection time and prevalence of ascites in the LHM group were significantly lower than those in the non-LHM group (p < 0.05). In CLM patients, tumor recurrence rate in the non-LHM group was significantly higher than that in the LHM group and disease-free survival in the LHM group was significantly better than that in the non-LHM group in CLM patients and, however, this difference was not observed in a large CLM exceeding 5 cm. However, significant differences of posthepatectomy disease-free and overall survivals were not observed in HCC, ICC and BDC patients. CONCLUSIONS Although advantages of LHM improving surgical records in major anatomical liver resections were clarified, oncological advantages in the long-term survival of LHM was still uncertain in the hepatobiliary malignancies.

Radiation-Induced Esophageal Leiomyosarcoma 13 Years after Mediastinal Irradiation Following Surgical Removal of a Thymoma

Radiation-induced leiomyosarcoma is a very rare complication following irradiation of primary malignancies. In the chest wall, it is usually secondary to radiotherapy for breast cancer or lymphoma. Esophageal malignancy is a radiation dose-related complication of radiotherapy for breast cancer, but its absolute risk is low. A 61-year-old woman presented with an esophageal leiomyosarcoma 13 years after surgery plus mediastinal irradiation (55 Gy) for a stage III thymoma. Esophageal sarcoma is an uncommon tumor, reported sporadically in the literature. Radiotherapy is frequently used in the treatment of carcinoma of the esophagus, and the increased risk of development of sarcoma arising in irradiated fields is well known. The increasing use of radiotherapy for thymoma suggests that radiation-associated malignancies of the esophagus may be seen more frequently in the future. To the best of our knowledge, this is the first report of radiation-induced esophageal leiomyosarcoma after mediastinal irradiation of a thymoma.