Metastatic seminoma in the duodenum: diagnosis with endoscopy followed by successful treatment

Seminomas rarely metastasize to the gastrointestinal tract. In general, these lesions metastasize to the lungs or retroperitoneal lymph nodes. A 34-year-old Japanese man who had undergone orchiectomy for seminoma two years earlier experienced shortness of breath and tarry stools. The patient presented at our hospital and was diagnosed with metastatic seminoma to the third portion of the duodenum on double balloon endoscopy. He was effectively treated with chemotherapy and continues to progress well, with no episodes of recurrence.

Altered expression and function of hepatic natural killer T cells in obese and diabetic KK-A(y) mice

AIM

  To evaluate the role of natural killer (NK)T cells in the pathogenesis of non-alcoholic steatohepatitis (NASH), here we investigated the expression and function of hepatic NKT cells in KK-A(y) mice, an animal model of metabolic syndrome.

METHODS

  Male, 8-week-old KK-A(y) and C57Bl/6 mice were fed a high-fat (HF) diet for 4 weeks. Some mice were given daily intragastric injections of pioglitazone for 5 days prior to or after dietary treatment.

RESULTS

  In untreated KK-A(y) mice, the percentages of NKT cells in liver mononucleolar cells were nearly one-third of those in C57Bl/6 controls. Elevations in interleukin (IL)-4 and interferon (IFN)-γ mRNA in the liver after a single injection of α-galactosylceramide (GalCer) were blunted in KK-A(y) mice largely. Percentages of NKT cells, as well as GalCer-induced increases in IL-4 mRNA, were blunted significantly in both strains after HF diet feeding for 4 weeks. Interestingly, KK-A(y) mice pretreated with pioglitazone showed significant increases in NKT cell proportion, and GalCer-induced increases in IL-4 and IFN-γ mRNA were also enhanced by pioglitazone. In KK-A(y) mice, the percentages of annexin V positive NKT cells were nearly 2.5-fold higher than those in C57Bl/6 controls; however, pioglitazone decreased annexin V positive cells significantly. Moreover, pioglitazone increased NKT cell fraction in KK-A(y) mice even after HF diet feeding.

CONCLUSION

  KK-A(y) mice exhibit proportional and functional alterations in hepatic NKT cells in close relation with the development of steatohepatitis, and it is postulated that pioglitazone improves steatohepatitis in part through restoration of hepatic NKT cells.

Innate immune responses involving natural killer and natural killer T cells promote liver regeneration after partial hepatectomy in mice

To clarify the roles of innate immune cells in liver regeneration, here, we investigated the alteration in regenerative responses after partial hepatectomy (PH) under selective depletion of natural killer (NK) and/or NKT cells. Male, wild-type (WT; C57Bl/6), and CD1d-knockout (KO) mice were injected with anti-NK1.1 or anti-asialo ganglio-N-tetraosylceramide (GM1) antibody and then underwent the 70% PH. Regenerative responses after PH were evaluated, and hepatic expression levels of cytokines and growth factors were measured by real-time RT-PCR and ELISA. Phosphorylation of STAT3 was detected by Western blotting. Depletion of both NK and NKT cells with an anti-NK1.1 antibody in WT mice caused drastic decreases in bromodeoxyuridine uptake, expression of proliferating cell nuclear antigen, and cyclin D1, 48 h after PH. In mice given NK1.1 antibody, increases in hepatic TNF-α, IL-6/phospho-STAT3, and hepatocyte growth factor (HGF) levels following PH were also blunted significantly, whereas IFN-γ mRNA levels were not different. CD1d-KO mice per se showed normal liver regeneration; however, pretreatment with an antiasialo GM1 antibody to CD1d-KO mice, resulting in depletion of both NK and NKT cells, also blunted regenerative responses. Collectively, these observations clearly indicated that depletion of both NK and NKT cells by two different ways results in impaired liver regeneration. NK and NKT cells most likely upregulate TNF-α, IL-6/STAT3, and HGF in a coordinate fashion, thus promoting normal regenerative responses in the liver.

Ursolic acid ameliorates hepatic fibrosis in the rat by specific induction of apoptosis in hepatic stellate cells

BACKGROUND & AIMS

Specific induction of cell death in activated hepatic stellate cells (HSCs) is a promising therapeutic strategy for hepatic fibrosis. In this study, we evaluated the cell-killing effect of ursolic acid (UA), a pentacyclic triterpenoid, in activated HSCs both in vitro and in vivo.

METHODS

Culture-activated rat HSCs were treated with UA (0-40μM), and the mechanisms of cell death were evaluated. The cell killing effect of UA on activated HSCs in rats chronically treated with thioacetamide (TAA) was detected by dual staining of TdT-mediated dUTP nick-end labeling (TUNEL) and smooth muscle α-actin (αSMA) immunohistochemistry, and resolution of hepatic fibrosis was evaluated. Further, the protective effects of UA on progression of hepatic fibrosis caused by TAA and bile duct ligation (BDL) were evaluated.

RESULTS

UA induced apoptotic cell death in culture-activated HSCs, but not in isolated hepatocytes and quiescent HSCs. Mitochodrial permeability transition (MPT) preceded the cleavage of caspase-3 and -9 following UA treatment. UA also decreased phosphorylation levels of Akt, and diminished nuclear localization of NFκB in these cells. In rats pretreated with TAA for 6weeks, a single injection of UA induced remarkable increases in TUNEL- and αSMA-dual-positive cells in 24h, and significant regression of hepatic fibrosis within 48h. Moreover, UA ameliorated hepatic fibrogenesis caused by both chronic TAA administration and BDL.

CONCLUSIONS

UA ameliorated experimental hepatic fibrosis most likely through specific induction of apoptosis in activated HSCs. It is therefore postulated that UA is a potential therapeutic reagent for resolution of hepatic fibrosis.

CD1d-restricted natural killer T cells contribute to hepatic inflammation and fibrogenesis in mice

BACKGROUND & AIMS

Several lines of evidence suggest that innate immunity plays a key role in hepatic fibrogenesis. To clarify the role of natural killer (NK) T cells in hepatic inflammation and fibrogenesis, we here investigated xenobiotics-induced liver injury and subsequent fibrogenesis in mice lacking mature NKT cells caused by genetic disruption of the CD1d molecule.

METHODS

Male CD1d-knockout (KO) and wild-type (WT) mice were given repeated intraperitoneal injections of thioacetamide (TAA, 3times/week; 0.1-0.2mg/g BW) for up to 9 weeks, or a single intraperitoneal injection of CCl(4) (1 μl/g). Liver histology was evaluated, and expression levels of cytokines and matrix-related genes in the liver were quantitatively measured by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Mortality following repeated injections of TAA was prevented almost completely in CD1d-KO mice. TAA-induced inflammatory responses and hepatocellular damage were markedly ameliorated in CD1d-KO mice. TAA-induced expression of smooth muscle α-actin (SMA) and transforming growth factor (TGF)β1 mRNA in the liver were also prevented largely in CD1d-KO mice. In fact, CD1d-KO mice developed minimal hepatic fibrosis after 9-weeks of administration of TAA, which caused overt bridging fibrosis in WT mice. Indeed, TAA-induced increases in α1(I)procollagen (COL1A1) and tissue inhibitor of matrix metalloproteinase (TIMP)-1 mRNA were blunted significantly in CD1d-KO mice. Similarly, acute CCl(4)-induced hepatic injury and subsequent profibrogenic responses were also reduced significantly in CD1d-KO mice.

CONCLUSIONS

These findings clearly indicated that CD1d-restricted NKT cells contribute to xenobiotics-induced hepatic inflammation, hepatocellular damage, and subsequent profibrogenic responses in the liver.

Metastatic renal cell carcinoma diagnosed by capsule endoscopy and double balloon endoscopy

Background

Renal cell carcinoma commonly metastasizes to lung, liver, and bone. Small intestinal metastases are exceedingly rare.

Case Report

A 75-year-old man presented at our hospital with tarry stools. He had undergone a right nephrectomy for renal cell carcinoma (RCC) 6 years previously; in addition, he had received antiplatelet treatment for ischemic heart disease. Esophagogastroduodenoscopy, total colonoscopy, and computed tomography did not identify any cause for the gastrointestinal bleeding. He underwent capsule endoscopy (CE), which revealed an ulcerated submucosal tumor in the jejunum. We performed a double-balloon endoscopy (DBE), and histological findings identified a clear cell carcinoma. We diagnosed metastasis from the RCC. We performed a jejunectomy to resect the tumor and thus eliminate the source of the bleeding.

Conclusions

CE and DBE are useful diagnostic tools. We recommend investigating the possibility of small intestinal metastases in cases of intestinal bleeding or anemia in patients with a history of malignant tumor.

Diabetic KK-A(y) mice are highly susceptible to oxidative hepatocellular damage induced by acetaminophen

Despite pathophysiological similarities to alcoholic liver disease, susceptibility to acetaminophen hepatotoxicity in metabolic syndrome-related nonalcoholic steatohepatitis (NASH) has not been well elucidated. In this study, therefore, we investigated acetaminophen-induced liver injury in KK-A(y) mice, an animal model of metabolic syndrome. Twelve-week-old male KK-A(y) and C57Bl/6 mice were injected intraperitoneally with 300 or 600 mg/kg acetaminophen, and euthanized 6 h later. Liver histology was assessed, and hepatic expression of 4-hydroxy-2-nonenal was detected by immunohistochemistry. Levels of reduced glutathione were determined spectrophotometrically. Phosphorylation of c-Jun NH(2)-terminal kinase (JNK) was analyzed by Western blotting. Hepatocytes were isolated from both strains by collagenase perfusion, and cell death and oxidative stress were measured fluorometrically by use of propidium iodide and 5-(and-6)-chloromethyl-2'7'-dichloro-dihydrofluorescein diacetate acetyl ester, respectively. Acetaminophen induced more severe necrosis and apoptosis of hepatocytes in KK-A(y) mice than in C57Bl/6 mice and significantly increased serum alanine aminotransferase levels in KK-A(y) mice. Acetaminophen-induction of 4-hydroxy-2-nonenal in the liver was potentiated, whereas the levels of reduced glutathione in liver were lower in KK-A(y) mice. Acetaminophen-induced phosphorylation of JNK in the liver was also enhanced in KK-A(y) mice. Exposure to 20 microM tert-butyl hydroperoxide did not kill hepatocytes isolated from C57Bl/6 mice but induced cell death and higher oxidative stress in hepatocytes from KK-A(y) mice. These results demonstrated that acetaminophen toxicity is increased in diabetic KK-A(y) mice mainly due to enhanced oxidative stress in hepatocytes, suggesting that metabolic syndrome-related steatohepatitis is an exacerbating factor for acetaminophen-induced liver injury.

Lysosomal iron mobilization and induction of the mitochondrial permeability transition in acetaminophen-induced toxicity to mouse hepatocytes

Acetaminophen induces the mitochondrial permeability transition (MPT) in hepatocytes. Reactive oxygen species (ROS) trigger the MPT and play an important role in AAP-induced hepatocellular injury. Because iron is a catalyst for ROS formation, our aim was to investigate the role of chelatable iron in MPT-dependent acetaminophen toxicity to mouse hepatocytes. Hepatocytes were isolated from fasted male C3Heb/FeJ mice. Necrotic cell killing was determined by propidium iodide fluorometry. Mitochondrial membrane potential was visualized by confocal microscopy of tetramethylrhodamine methylester. Chelatable ferrous ion was monitored by calcein quenching, and 70 kDa rhodamine-dextran was used to visualize lysosomes. Cell killing after acetaminophen (10mM) was delayed and decreased by more than half after 6 h by 1mM desferal or 1mM starch-desferal. In a cell-free system, ferrous but not ferric iron quenched calcein fluorescence, an effect reversed by dipyridyl, a membrane-permeable iron chelator. In hepatocytes loaded with calcein, intracellular calcein fluorescence decreased progressively beginning about 4 h after acetaminophen. Mitochondria then depolarized after about 6 h. Dipyridyl (20mM) dequenched calcein fluorescence. Desferal and starch-desferal conjugate prevented acetaminophen-induced calcein quenching and mitochondrial depolarization. As calcein fluorescence became quenched, lysosomes disappeared, consistent with release of iron from ruptured lysosomes. In conclusion, an increase of cytosolic chelatable ferrous iron occurs during acetaminophen hepatotoxicity, which triggers the MPT and cell killing. Disrupted lysosomes are the likely source of iron, and chelation of this iron decreases acetaminophen toxicity to hepatocytes.

Synthetic triglyceride containing an arachidonic acid branch (8A8) prevents lipopolysaccharide-induced liver injury

AIMS

In this study, we investigated the effect of synthetic triglyceride containing an arachidonic acid branch (8A8) on lipopolysaccharide (LPS)-induced production of tumor necrosis factor (TNF)-alpha and nitric oxide (NO) in macrophages, and LPS-induced liver injury in the rat.

MAIN METHODS

RAW264.7 macrophages were co-incubated with 8A8 and LPS (100ng/ml), and TNF-alpha mRNA/protein levels, nuclear factor (NF)-kappaB DNA binding activity, expression of inducible-type NO synthase (NOS2), and NO(2) production were measured. Male Wistar rats were given a single intraperitoneal injection of 8A8 prior to an intravenous injection of LPS (5mg/kg), and liver histology, apoptotic cell death, serum TNF-alpha levels, and hepatic TNF-alpha mRNA were then evaluated.

KEY FINDINGS

LPS-induced increases in TNF-alpha production in RAW264.7 macrophages were blunted by 8A8 in a dose-dependent manner, with 40% inhibition at 100ppm. Further, 8A8 dose-dependently prevented LPS-induced increases in TNF-alpha mRNA levels, as well as NF-kappaB DNA binding activities, in RAW264.7 macrophages. LPS-induction of NOS2 and NO(2) release from these cells was also decreased by 8A8 in a dose-dependent manner. In vivo, LPS-induced liver injury, including hepatocyte apoptosis, was largely prevented when 8A8 (100microl/kg) was given 30min prior to LPS. Indeed, 8A8 blunted increases in both serum TNF-alpha and hepatic TNF-alpha mRNA levels significantly.

SIGNIFICANCE

LPS-induced liver injury was prevented by 8A8 most likely through the inhibition of TNF-alpha and NO production from hepatic macrophages, suggesting a potential usefulness of 8A8 as an immuno-modulating nutrient for prevention/treatment of endotoxin-related organ injuries including alcoholic liver disease and non-alcoholic steatohepatitis (NASH).

Pioglitazone promotes survival and prevents hepatic regeneration failure after partial hepatectomy in obese and diabetic KK-A(y) mice

Pathogenesis of metabolic syndrome-related nonalcoholic steatohepatitis (NASH) involves abnormal tissue-repairing responses in the liver. We investigated the effect of pioglitazone, a thiazolidinedione derivative (TZD), on hepatic regenerative responses in obese, diabetic KK-A(y) mice. Male KK-A(y) mice 9 weeks after birth underwent two-thirds partial hepatectomy (PH) after repeated intragastric injections of pioglitazone (25 mg/kg) for 5 days. Almost half of the KK-A(y) mice died within 48 hours of PH;however, mortality was completely prevented in mice pretreated with pioglitazone. In KK-A(y) mice, bromodeoxyuridine (BrdU) incorporation to hepatocyte nuclei 48 hours after PH reached only 1%; however, pioglitazone pretreatment significantly increased BrdU-positive cells to 8%. Cyclin D1 was barely detectable in KK-A(y) mice within 48 hours after PH. In contrast, overt expression of cyclin D1 was observed 24 hours after PH in KK-A(y) mice pretreated with pioglitazone. Hepatic tumor necrosis factor alpha (TNF-alpha) messenger RNA (mRNA) was tremendously increased 1 hour after PH in KK-A(y) mice, the levels reaching ninefold over C57Bl/6 given PH, whereas pioglitazone blunted this increase by almost three-fourths. Pioglitazone normalized hypoadiponectinemia in KK-A(y) mice almost completely. Serum interleukin (IL)-6 and leptin levels were elevated extensively 24 hours after PH in KK-A(y) mice, whereas the levels were largely decreased in KK-A(y) mice given pioglitazone. Indeed, pioglitazone prevented aberrant increases in signal transducers and activators of transcription (STAT)3 phosphorylation and suppressor of cytokine signaling (SOCS)-3 mRNA in the liver in KK-A(y) mice.

CONCLUSION

These findings indicated that pioglitazone improved hepatic regeneration failure in KK-A(y) mice. The mechanism underlying the effect of pioglitazone on regeneration failure most likely involves normalization of expression pattern of adipokines and subsequent cytokine responses during the early stage of PH.

Translocation of iron from lysosomes into mitochondria is a key event during oxidative stress-induced hepatocellular injury

Iron overload exacerbates various liver diseases. In hepatocytes, a portion of non-heme iron is sequestered in lysosomes and endosomes. The precise mechanisms by which lysosomal iron participates in hepatocellular injury remain uncertain. Here, our aim was to determine the role of intracellular movement of chelatable iron in oxidative stress-induced killing to cultured hepatocytes from C3Heb mice and Sprague-Dawley rats. Mitochondrial polarization and chelatable iron were visualized by confocal microscopy of tetramethylrhodamine methylester (TMRM) and quenching of calcein, respectively. Cell viability and hydroperoxide formation (a measure of lipid peroxidation) were measured fluorometrically using propidium iodide and chloromethyl dihydrodichlorofluorescein, respectively. After collapse of lysosomal/endosomal acidic pH gradients with bafilomycin (50 nM), an inhibitor of the vacuolar proton-pumping adenosine triphosphatase, cytosolic calcein fluorescence became quenched. Deferoxamine mesylate and starch-deferoxamine (1 mM) prevented bafilomycin-induced calcein quenching, indicating that bafilomycin induced release of chelatable iron from lysosomes/endosomes. Bafilomycin also quenched calcein fluorescence in mitochondria, which was blocked by 20 microM Ru360, an inhibitor of the mitochondrial calcium uniporter, consistent with mitochondrial iron uptake by the uniporter. Bafilomycin alone was not sufficient to induce mitochondrial depolarization and cell killing, but in the presence of low-dose tert-butylhydroperoxide (25 microM), bafilomycin enhanced hydroperoxide generation, leading to mitochondrial depolarization and subsequent cell death.

CONCLUSION

Taken together, the results are consistent with the conclusion that bafilomycin induces release of chelatable iron from lysosomes/endosomes, which is taken up by mitochondria. Oxidative stress and chelatable iron thus act as two "hits" synergistically promoting toxic radical formation, mitochondrial dysfunction, and cell death. This pathway of intracellular iron translocation is a potential therapeutic target against oxidative stress-mediated hepatotoxicity.

Role of adipocytokines in hepatic fibrogenesis

Obesity and insulin resistance are the key factors for progression of hepatic fibrosis in various chronic liver diseases including non-alcoholic steatohepatitis (NASH). Recently it has been shown that leptin plays a pivotal role in development of hepatic fibrosis. Leptin promotes hepatic fibrogenesis through upregulation of transforming growth factor-beta in Kupffer cells and sinusoidal endothelial cells. Further, leptin facilitates proliferation and prevents apoptosis of hepatic stellate cells. There is a paradox, however, in that ob/ob mice and Zucker rats, which are the obese and diabetic strains, had minimal profibrogenic responses in the liver, most likely because they lack leptin and its receptors. To establish a more clinically relevant model to study the mechanism of fibrogenesis under steatohepatitis, fatty changes and profibrogenic responses in the liver caused by methionine-choline deficiency (MCD) were investigated in the KK-A(y) mouse, which is an obese and diabetic strain. KK-A(y) mice developed more severe hepatic steatosis, inflammation and fibrosis induced by an MCD diet as compared to C57Bl/6 controls. Importantly, KK-A(y) mice lack physiological upregulation of adiponectin levels, suggesting that adiponectin plays a pivotal role not only in regulation of insulin sensitivity but also in modulation of inflammatory and profibrogenic responses in dietary steatohepatitis. Collectively, these findings support the hypothesis that the balance of adipocytokine expression is a key regulator for the progression of hepatic fibrosis in the setting of steatohepatitis.

Role of apoptosis in acetaminophen hepatotoxicity

Acetaminophen overdose causes liver injury by mechanisms involving glutathione depletion, oxidative stress and mitochondrial dysfunction. The role of apoptosis in acetaminophen-induced cell killing is still controversial. Here, our aim was to evaluate the mitochondrial permeability transition (MPT) as a key factor in acetaminophen-induced necrotic and apoptotic killing of primary cultured mouse hepatocytes. Acetaminophen (10 micromol/L) induced necrotic killing in approximately 50% of hepatocytes after 6 h and cyclosporin A (CsA), MPT inhibitor, temporarily decreased necrotic killing after 6 h, but cytoprotection was lost after 16 h. Confocal microscopy revealed mitochondrial depolarization and inner membrane permeabilization at approximately 4.5 h after acetaminophen. CsA delayed these changes indicative of the MPT to about 11 h after acetaminophen. TUNEL labeling and caspase 3 activation also increased after acetaminophen. Fructose (20 mmol/L, an ATP-generating glycolytic substrate) plus glycine (5 mmol/L, a membrane stabilizing amino acid) prevented nearly all necrotic cell killing but paradoxically increased apoptosis. In conclusion, acetaminophen induces the MPT and ATP-depletion-dependent necrosis or caspase-dependent apoptosis as determined, in part, by ATP availability from glycolysis.

Exacerbation of dietary steatohepatitis and fibrosis in obese, diabetic KK-A(y) mice

In this study, we investigated a dietary model of steatohepatitis caused by methionine- and choline-deficiency (MCD) in obese, diabetic KK-A(y) mice. Male KK-A(y) mice and C57Bl/6 mice were fed an MCD diet for up to 8 weeks, and liver pathology was evaluated. Hepatic steatosis and inflammatory infiltration were more prominent in KK-A(y) mice than in C57Bl/6 mice 4 weeks after feeding with MCD diet. MCD diet-induced increases in tumor necrosis factor (TNF)-alpha mRNA levels, as well as lipid peroxidation, in the liver were also potentiated significantly in KK-A(y) mice. Extended degree of hepatic fibrosis was observed in KK-A(y) mice as compared to C57Bl/6 mice 8 weeks after feeding with MCD diet. Indeed, alpha1(I)procollagen and transforming growth factor (TGF)-beta1 mRNA levels were significantly higher in KK-A(y) mice following dietary treatment. Serum adiponectin levels were elevated nearly two-fold when C57Bl/6 mice were given MCD diet for 4 weeks; however, serum adiponectin levels in KK-A(y) mice fed both the control- and MCD diet were the same, reaching the values almost 1/2 of those in C57Bl/6 mice. In conclusion, KK-A(y) mice exhibit increased susceptibility to MCD diet-induced steatohepatitis, where hypoadiponectinemia most likely plays a key role in exacerbation of both inflammatory and profibrogenic responses.

Hepatic steatosis is a predictor of poor response to interferon alpha-2b and ribavirin combination therapy in Japanese patients with chronic hepatitis C

In this study, we evaluated whether hepatic steatosis affects the viral response to interferon (IFN) and ribavirin combination therapy in Japanese patients with chronic hepatitis C (CHC). Eighty CHC patients treated with IFN alpha-2b and ribavirin for 24 weeks were evaluated retrospectively. Liver biopsy specimens were assessed histopathologically, and grade of steatosis was scored as follows: grade 0: <5%; grade 1: 5-33%; grade 2: 33-66%; grade 3: >66%. Sustained viral response (SVR) was defined as negative for HCV-RNA by high-sensitivity qualitative reverse transcription-polymerase chain reaction (RT-PCR) at 24 weeks post-treatment. Hepatic steatosis graded 2 and higher was seen in 28.8% patients, whose average BMI were significantly higher than those in grade 0 patients. Grade of steatosis was well correlated with elevation in serum aminotransferases and gamma-glutamyltranspeptidase (gamma-GTP) levels, but not with histological degree of inflammation and fibrosis. The SVR rates were significantly lower in the group with overt steatosis (grade 2/3) as compared to the group with less steatosis (grade 0/1), the values being 30.4% and 57.9%, respectively. Moreover, grade of steatosis was selected as an independent negative factor for SVR in multivariate analysis. In conclusion, hepatic steatosis is an important predictor of poor response to therapy of IFNalpha-2b and ribavirin in patients with CHC.

[Serine protease inhibitors prevent alcoholic liver injury]

The hepatotoxic effects of alcohol have been described in detail, but factors responsible for its hepatotoxicity have only partially characterized. It now appears that Kupffer cell derived TNF-alpha participates in several aspects of alcoholic liver injury. On the other hand, protease inhibitors have been used successfully for treatment of intractable diseases in which TNF-alpha is involved in the pathogenesis, including ulcerative colitis and Crohn's disease. Here, we will review new evidence for the proposal that serine protease inhibitors prevents alcoholic liver injury via mechanisms dependent on Kupffer cell derived TNF-alpha.

Mitochondrial permeability transition in acetaminophen-induced necrosis and apoptosis of cultured mouse hepatocytes

Acetaminophen overdose causes massive hepatic failure via mechanisms involving glutathione depletion, oxidative stress, and mitochondrial dysfunction. The ultimate target of acetaminophen causing cell death remains uncertain, and the role of apoptosis in acetaminophen-induced cell killing is still controversial. Our aim was to evaluate the mitochondrial permeability transition (MPT) as a key factor in acetaminophen-induced necrotic and apoptotic killing of primary cultured mouse hepatocytes. After administration of 10 mmol/L acetaminophen, necrotic killing increased to more than 49% and 74%, respectively, after 6 and 16 hours. MPT inhibitors, cyclosporin A (CsA), and NIM811 temporarily decreased necrotic killing after 6 hours to 26%, but cytoprotection was lost after 16 hours. Confocal microscopy revealed mitochondrial depolarization and inner membrane permeabilization approximately 4.5 hours after acetaminophen administration. CsA delayed these changes, indicative of the MPT, to approximately 11 hours after acetaminophen administration. Apoptosis indicated by nuclear changes, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and caspase-3 activation also increased after acetaminophen administration. Fructose (20 mmol/L, an adenosine triphosphate-generating glycolytic substrate) plus glycine (5 mmol/L, a membrane stabilizing amino acid) prevented nearly all necrotic cell killing but paradoxically increased apoptosis from 37% to 59% after 16 hours. In the presence of fructose plus glycine, CsA decreased apoptosis and delayed but did not prevent the MPT. In conclusion, after acetaminophen a CsA-sensitive MPT occurred after 3 to 6 hours followed by a CsA-insensitive MPT 9 to 16 hours after acetaminophen. The MPT then induces ATP depletion-dependent necrosis or caspase-dependent apoptosis as determined, in part, by ATP availability from glycolysis.

Nitric oxide synthase inhibition by N(G)-nitro-L-arginine methyl ester retards vascular sprouting in angiogenesis

The present study was designed to evaluate the role of nitric oxide (NO) for angiogenesis. Angiogenesis was elicited upon mouse cornea by chemical cautery with silver nitrate. Angiogenic activity was evaluated by measuring the length of vascular sprout with or without administration of NO synthase (NOS) inhibitor, N((G))-nitro-L-arginine-methyl ester (L-NAME). In the pericorneal plexus, a circulatory loop situated in the same topological situation for all individuals was selected to observe vascular sprouting. At 72 h after cauterization, the length of the longest vascular sprout was measured using the perfused whole-mount cornea. The length of nontreated mice (83 +/- 83 microm) was significantly longer than that of L-NAME treated mice (33 +/- 24.6 microm). To address the possible contribution of production of vascular endothelial growth factor (VEGF) and NO, we measured mRNAs of VEGF and inducible NOS. The mRNA level of VEGF increased to 170% of the nontreated level at 12 h after cauterization and returned to the nontreated level by 24 h after cauterization. mRNA of inducible NOS remained elevated 24 h after cauterization. These results suggest that the response of preexisting vessels to angiogenic stimulus via NO is of importance in the process of angiogenesis, i.e., vascular sprouting is promoted by NO production. This might be attributable to enhancement of an increase in vascular permeability and /or vasodilation via NO.

Pioglitazone prevents early-phase hepatic fibrogenesis caused by carbon tetrachloride

Here we investigated the effect of pioglitazone, a peroxisome proliferator-activated receptor (PPAR)-gamma ligand, on early-phase hepatic fibrogenesis in vivo caused by acute carbon tetrachloride (CCl(4)) administration in the rat. Pioglitazone (1 mg/kg BW) prevented pericentral fibrosis and induction of alpha-smooth muscle actin (SMA) 72 h after CCl(4) administration (1 ml/kg BW). CCl(4) induction of alpha1(I)procollagen mRNA in the liver was blunted by pioglitazone to the levels almost 2/3 of CCl(4) alone. Pioglitazone also prevented CCl(4)-induced hepatic inflammation and necrosis, as well as increases in serum tumor necrosis factor-alpha levels. Further, pioglitazone inhibited the induction of alphaSMA and type I collagen in primary cultured hepatic stellate cells in a dose-dependent manner. In conclusion, pioglitazone inhibits both hepatic inflammation and activation of hepatic stellate cells, thereby ameliorating early-phase fibrogenesis in the liver following acute CCl(4).

Mechanism of tonic spasms in West syndrome viewed from ictal SPECT findings

To clarify the pathophysiology of tonic spasms, 21 patients with West syndrome were analyzed using ictal and interictal single photon emission computed tomography (SPECT). We focused on whether ictal perfusion changes were observed in the focal cortical region. Eight of the patients studied showed definite focal cortical ictal hyperperfusion, indicating that there is a unique subset of West syndrome that can be classified as infantile localization-related epilepsy. Of those eight patients, only two showed asymmetric spasms, suggesting that seizure symptomatology in infants gives only limited information on the localization-related nature of epilepsy. Furthermore, the activation of subcortical structures by focal cortical regions might be attributable to the symmetric seizure phenomena. Thirteen patients showed a diffuse pattern in their ictal SPECTs; this probably included patients with diffuse hyperperfusion and those with no changes. The following have yet to be determined: (1) whether West syndrome is divided into subgroups based on the origin of spasms, in that some patients have the origin in the cortical hemisphere and some have the origin in structures other than the cortical hemisphere, such as the brain stem; (2) whether differences in ictal SPECT patterns reflect a unique nature of tonic spasms in West syndrome, where tonic spasms appear in clusters and the interval of each spasm is different among each patient.

Characterization of a novel triphosphonooctaosylceramide from the eggs of the sea hare, Aplysia kurodai

We have reported the existence of a triphosphonoglycosphingolipid, EGL-I, in the eggs of a sea gastropod, Aplysia kurodai [Yamada, S., Araki, S., Abe, S., Kon, K., Ando, S., and Satake, M. (1995) J. Biochem. 117, 794-799]. We have now isolated a novel glycosphingolipid, named EGL-II, from the eggs of Aplysia. By component analysis, sugar analysis, permethylation studies, fast atom bombardment-mass spectrometry, secondary ion mass spectrometry, and proton magnetic resonance spectrometry, its structure was revealed to be as follows: Galalpha1-->3(GlcNAcalpha1-->2)Galalpha1-->3(3-O-MeGalalpha1-->2)Galalpha1-->3[6'-O-(2-aminoethylphosphonyl)Galalpha1-->2](2-aminoethylphosphonyl-->6)Galbeta1-->4(2-aminoethylphosphonyl-->6)Glcbeta1-->1ceramide. The major aliphatic components of the ceramide are palmitic acid, stearic acid, and anteisononadeca-4-sphingenine.