MRI study of atherosclerotic plaque progression using ultrasmall superparamagnetic iron oxide in Watanabe heritable hyperlipidemic rabbits

OBJECTIVE

The purpose of this study was to evaluate plaque progression by using MRI with ultrasmall superparamagnetic iron oxide (USPIO) and by histopathological studies.

METHODS

We divided 12 Watanabe heritable hyperlipidemic (WHHL) rabbits into 4 groups based on their age (3, 9, 14 and 26 months) and injected them intravenously with 0.8 mmol (Fe) kg(-1) of USPIO (size, 32 nm; concentration, 15 mg dl(-1)). On the fifth post-injection day, they were again given an intravenous injection with 40 μmol kg(-1) of the same USPIO, and MR angiography (MRA) was performed. The signal-to-noise ratio (SNR) in regions of interest in the wall of the upper abdominal aorta was calculated on coronal images. Specimens from the same level of the aorta were subjected to iron staining and RAM-11 immunostaining and used for histopathological study. For statistical analysis of the MRA and histopathological findings, we used analysis of variance [Tukey's honest significant difference (HSD) test].

RESULTS

In 9-month-old rabbits, the SNR was significantly lower than in rabbits of the other ages (p < 0.01), and the area of RAM-11 (DAKO Corporation, Glostrup, Denmark) and iron uptake in the aortic wall was significantly larger (RAM-11, p < 0.01; iron, p < 0.05). These areas were the smallest in 3-month-old rabbits.

CONCLUSION

Histopathologically, the number of macrophages was the greatest in 9-month-old rabbits. Our findings indicate that the SNR on MRI scans reflects the number of macrophages in the aortic wall of WHHL rabbits.

ADVANCES IN KNOWLEDGE

USPIO-enhanced MRI visualized the accumulation of macrophages in early atherosclerotic plaques of WHHL rabbits in the course of natural progression.

Induction of autophagy restores the loss of sevoflurane cardiac preconditioning seen with prolonged ischemic insult

Sevoflurane preconditioning against myocardial ischemia-reperfusion injury is lost if the ischemic insult is too long. Emerging evidence suggests that induction of autophagy may also confer cardioprotection against ischemia-reperfusion injury. We examined whether induction of autophagy prolongs sevoflurane preconditioning protection during a longer ischemic insult. Isolated guinea pigs hearts were subjected to 30 or 45 min ischemia, followed by 120 min reperfusion (control). Anesthetic preconditioning was elicited with 2% sevoflurane for 10 min prior to ischemia (SEVO-30, SEVO-45). Chloramphenicol (autophagy upregulator, 300 µM) was administered starting 20 min before ischemia and throughout reperfusion in SEVO-45 (SEVO-45+CAP). To inhibit autophagy, 3-methyladenine (10 μM) was administered during sevoflurane administration in SEVO-45+CAP. Infarct size was determined by triphenyltetrazolium chloride stain. Tissue samples were obtained before ischemia to determine autophagy-related protein (microtubule-associated protein light chain I and II: LC3-I, II), Akt and glycogen synthase kinase 3β (GSK3β) expression using Western blot analysis. The effect of autophagy on calcium-induced mitochondrial permeability transition pore (MPTP) opening in isolated calcein-loaded mitochondria was assessed. Electron microscopy was used to detect autophagosomes. Infarct size was significantly reduced in SEVO-30, but not in SEVO-45. Chloramphenicol restored sevoflurane preconditioning lost by 45 min ischemia. There were more abundant autophagozomes and LC3-II expression was significantly increased in SEVO-45+CAP. Induction of autophagy before ischemia enhanced GSK3β phosphorylation and inhibition of calcium-induced MPTP opening. These effects were abolished by 3-methyladenine. Pre-ischemic induction of autophagy restores sevoflurane preconditioning lost by longer ischemic insult. This effect is associated with enhanced inhibition of MPTP by autophagy.

Sevoflurane induces cardioprotection through reactive oxygen species-mediated upregulation of autophagy in isolated guinea pig hearts

PURPOSE

Sevoflurane increases reactive oxygen species (ROS), which mediate cardioprotection against myocardial ischemia-reperfusion injury. Emerging evidence suggests that autophagy is involved in cardioprotection. We examined whether reactive oxygen species mediate sevoflurane preconditioning through autophagy.

METHODS

Isolated guinea pigs hearts were subjected to 30 min ischemia followed by 120 min reperfusion (control). Anesthetic preconditioning was elicited with 2 % sevoflurane for 10 min before ischemia (SEVO). The ROS-scavenger, N-(2-mercaptopropionyl) glycine (MPG, 1 mmol/l), was administered starting 30 min before ischemia to sevoflurane-treated (SEVO + MPG) or non-sevoflurane-treated (MPG) hearts. Infarct size was determined by triphenyltetrazolium chloride stain. Tissue samples were obtained after reperfusion to determine autophagy-related protein (microtubule-associated protein light chain I and II: LC3-I, -II) and 5' AMP-activated protein kinase (AMPK) expression using Western blot analysis. Electron microscopy was used to detect autophagosomes.

RESULTS

Infarct size was significantly reduced and there were more abundant autophagosomes in SEVO compared with control. Western blot analysis revealed that the ratio of LC3-II/I and phosphorylation of AMPK were significantly increased in SEVO. These effects were abolished by MPG.

CONCLUSIONS

Sevoflurane induces cardioprotection through ROS-mediated upregulation of autophagy.

A case of severe progressive early-onset epileptic encephalopathy: unique GABAergic interneuron distribution and imaging

Early-onset epileptic encephalopathies include various diseases such as early-infantile epileptic encephalopathy with suppression burst. We experimentally investigated the unique clinicopathological features of a 28-month-old girl with early-onset epileptic encephalopathy. Her initial symptom was intractable epilepsy with a suppression-burst pattern of electroencephalography (EEG) from 7 days of age. The suppression-burst pattern was novel, appearing during sleep, but disappearing upon waking and after becoming 2 months old. The EEG showed multifocal spikes and altered with age. Her seizures demonstrated various clinical features and continued until death. She did not show any developmental features, including no social smiling or head control. Head MRI revealed progressive atrophy of the cerebral cortex and white matter after 1 month of age. (123)IMZ-SPECT demonstrated hypo-perfusion of the cerebral cortex, but normo-perfusion of the diencephalon and cerebellum. Such imaging information indicated GABA-A receptor dysfunction of the cerebral cortex. The genetic analyses of major neonatal epilepsies showed no mutation. The neuropathology revealed atrophy and severe edema of the cerebral cortex and white matter. GAD-immunohistochemistry exhibited imbalanced distribution of GABAergic interneurons between the striatum and cerebral cortex. The results were similar to those of focal cortical dysplasia with transmantle sign and X-linked lissencephaly with ARX mutation. We performed various metabolic examinations, detailed pathological investigations and genetic analyses, but could not identify the cause. To our knowledge, her clinical and pathological courses have never been described in the literature.

Sevoflurane confers additive cardioprotection to ethanol preconditioning associated with enhanced phosphorylation of glycogen synthase kinase-3β and inhibition of mitochondrial permeability transition pore opening

OBJECTIVE

The purposes of this study were to investigate whether sevoflurane (SEVO) enhances moderate-dose ethanol (EtOH) preconditioning and whether this additional cardioprotection is associated with glycogen synthase kinase-3β (GSK-3β), protein kinase B (Akt), mammalian target of rapamycin (mTOR), 70-kDa ribosomal s6 kinase-1 (p70s6K), and/or mitochondrial permeability transition pore (MPTP) opening.

DESIGN

In vitro study using an isolated heart Langendorff preparation.

SETTING

University research laboratory.

PARTICIPANTS

Male guinea pigs (n = 170).

INTERVENTIONS

Isolated perfused guinea pig hearts underwent 30-minute ischemia and 120-minute reperfusion (control). The EtOH group received 5% EtOH in the drinking water for 8 weeks. Anesthetic preconditioning was elicited by a 10-minute exposure to 2% SEVO in EtOH (EtOH + SEVO group) or non-EtOH (SEVO group) hearts. The inhibition of GSK-3β phosphorylation and mTOR was achieved with LY294002 and rapamycin, respectively. GSK-3β, Akt, mTOR, and p70s6K expressions were determined by western blot. Calcium-induced MPTP opening was assessed in isolated calcein-loaded mitochondria.

MEASUREMENTS AND MAIN RESULTS

After ischemia-reperfusion, the EtOH, SEVO, and EtOH + SEVO groups had higher left ventricular developed pressure recovery and lower end-diastolic pressure versus the control group. Infarct size was smaller in the EtOH and SEVO groups versus control and even smaller in the EtOH + SEVO group. Phosphorylation of GSK-3β and Akt, but not mTOR and p70s6K, was increased in the EtOH and SEVO groups. Phosphorylation of GSK-3β, but not mTOR and p70s6K, was further increased in the EtOH + SEVO group. The EtOH and SEVO groups exhibited a smaller calcium-induced MPTP opening, and the EtOH + SEVO presented an even smaller MPTP opening.

CONCLUSIONS

SEVO and chronic EtOH preconditioning offer additive cardioprotection. This effect is associated with an increased GSK-3β phosphorylation and an inhibition of MPTP opening.

Determinants of outcomes following acute child encephalopathy and encephalitis: pivotal effect of early and delayed cooling

BACKGROUND

Acute encephalopathy/encephalitis is one of the most important causatives of mortality and neurological deficit during childhood. The aim of this retrospective observational study was to investigate clinical variables and therapeutic options associated with the outcome of children with acute encephalopathy/encephalitis.

METHODS

Relationships between the clinical information at admission and the neurological outcome evaluated using Pediatric Cerebral Performance Category Scale (PCPC) at 12 months after admission were assessed in 43 patients who were treated at 10 Japanese paediatric intensive care units.

RESULTS

Sixteen patients were cared for at normothermia, whereas mild hypothermia was applied to 27 children. In univariate analysis, ages ≤ 18 months, marked elevation in serum lactate dehydrogenase (LD) and aspartate transaminase, diagnosis of either acute necrotising encephalopathy or haemorrhagic shock and encephalopathy syndrome and longer hypothermic periods were associated with increased risks of death or severe neurological deficit, whereas hypothermia showed pivotal effects: the outcome of children cooled after 12 h of diagnosis was statistically invariant with normothermic children, but was significantly worse compared with children cooled ≤ 12 h. In multivariate analysis, younger ages and elevated serum LD were associated with adverse outcomes, whereas early initiation of cooling was related to favourable outcomes. For normothermic children, PCPC scores were dependent on the computed tomographic findings suggestive of cerebral oedema, serum LD levels and Glasgow Coma Scale at admission. For hypothermic children, PCPC scores depended on longer delays in cooling initiation.

CONCLUSION

Without therapeutic hypothermia, the outcome of children was determined by variables suggestive of the severity of encephalopathy/encephalitis at admission. Hypothermia may have pivotal impacts on the outcome of children according to the timing of cooling initiation following acute encephalopathy/encephalitis.

Acute encephalitis with refractory, repetitive partial seizures (AERRPS): a peculiar form of childhood encephalitis

OBJECTIVE

We conducted a nationwide multicenter study in Japan to elucidate the clinical and laboratory characteristics of acute encephalitis with refractory, repetitive partial seizures (AERRPS).

MATERIALS AND METHODS

Clinical and laboratory features, treatment, and outcome were assessed using a structured questionnaire.

RESULTS

Twenty-nine children were enrolled in the study. Refractory and repetitive partial seizures accompanied by fever were the cardinal clinical features. Partial seizures consisted principally of eye deviation or facial twitching, being periodically repeated during the acute phase. These seizures were refractory to conventional anticonvulsants and were only suppressed by high-dose intravenous barbiturate administration. Rhythmic activities on electroencephalography and non-specific cerebral atrophy on neuroimaging were common. Serum or cerebrospinal antibodies against GluRepsilon2 were positive in six patients. General prognosis was unfavorable due to intractable epilepsy and cognitive deficits.

CONCLUSION

Based on the peculiar and homogenous features, AERRPS can be regarded as a distinct clinical entity.

Acute encephalopathy associated with influenza and other viral infections

Acute encephalopathy is the most serious complication of pediatric viral infections, such as influenza and exanthem subitum. It occurs worldwide, but is most prevalent in East Asia, and every year several hundreds of Japanese children are affected by influenza-associated encephalopathy. Mortality has recently declined, but is still high. Many survivors are left with motor and intellectual disabilities, and some with epilepsy. This article reviews various syndromes of acute encephalopathy by classifying them into three major categories. The first group caused by metabolic derangement consists of various inherited metabolic disorders and the classical Reye syndrome. Salicylate is a risk factor of the latter condition. The second group, characterized by a systemic cytokine storm and vasogenic brain edema, includes Reye-like syndrome, hemorrhagic shock and encephalopathy syndrome, and acute necrotizing encephalopathy. Non-steroidal anti-inflammatory drugs, such as diclofenac sodium and mephenamic acid, may aggravate these syndromes. Severe cases are complicated by multiple organ failure and disseminated intravascular coagulation. Mortality is high, although methylprednisolone pulse therapy may be beneficial in some cases. The third group, characterized by localized edema of the cerebral cortex, has recently been termed acute encephalopathy with febrile convulsive status epilepticus, and includes hemiconvulsion-hemiplegia syndrome and acute infantile encephalopathy predominantly affecting the frontal lobes. Theophylline is a risk factor of these syndromes. The pathogenesis is yet to be clarified, but an increasing body of evidence points to excitotoxicity and delayed neuronal death.

Acute encephalopathy associated with influenza and other viral infections

Acute encephalopathy is the most serious complication of pediatric viral infections, such as influenza and exanthem subitum. It occurs worldwide, but is most prevalent in East Asia, and every year several hundreds of Japanese children are affected by influenza-associated encephalopathy. Mortality has recently declined, but is still high. Many survivors are left with motor and intellectual disabilities, and some with epilepsy. This article reviews various syndromes of acute encephalopathy by classifying them into three major categories. The first group caused by metabolic derangement consists of various inherited metabolic disorders and the classical Reye syndrome. Salicylate is a risk factor of the latter condition. The second group, characterized by a systemic cytokine storm and vasogenic brain edema, includes Reye-like syndrome, hemorrhagic shock and encephalopathy syndrome, and acute necrotizing encephalopathy. Non-steroidal anti-inflammatory drugs, such as diclofenac sodium and mephenamic acid, may aggravate these syndromes. Severe cases are complicated by multiple organ failure and disseminated intravascular coagulation. Mortality is high, although methylprednisolone pulse therapy may be beneficial in some cases. The third group, characterized by localized edema of the cerebral cortex, has recently been termed acute encephalopathy with febrile convulsive status epilepticus, and includes hemiconvulsion-hemiplegia syndrome and acute infantile encephalopathy predominantly affecting the frontal lobes. Theophylline is a risk factor of these syndromes. The pathogenesis is yet to be clarified, but an increasing body of evidence points to excitotoxicity and delayed neuronal death.

Enhanced atherosclerosis in Lp(a) WHHL transgenic rabbits

High lipoprotein(a) [Lp(a)] levels form a major risk factor for the development of atherosclerosis. The risk of elevated Lp(a) concentrations is significantly increased in patients who also have high levels of LDL cholesterol. Although the relation between Lp(a) and atherosclerosis has been reported in numerous studies, little is known about whether Lp(a) would exacerbate the complicated lesion formation in vivo. To test the hypothesis that increased plasma levels of Lp(a) may enhance the development of atherosclerosis in the setting of hypercholesterolemia, we generated WHHL transgenic rabbits expressing human apolipoprotein (a) and compared the atherosclerotic lesions with those of nontransgenic WHHL rabbits.

Stability of atheromatous plaque affected by lesional composition: study of WHHL rabbits treated with statins

We examined how lesional composition is related to the stability of coronary plaques. WHHL rabbits (12 months old) were given pravastatin and fluvastatin orally for 52 weeks. Both statins decreased plasma cholesterol levels by about 25%, but the suppressive effects on the degree of coronary plaques were mild. Macrophage (Mphi) contents in fibromuscular cap regions were decreased by pravastatin, and smooth muscle cell (SMC) contents in those were decreased by fluvastatin. The plaque vulnerability index was low in Mphi)-poor plaques, but high in SMC-poor plaques. Our results suggest that reduction in M(phi)s in the fibromuscular cap is related to plaque stabilization and that reduction in SMCs in the fibromuscular cap is related to plaque destabilization.

MTP inhibitor decreases plasma cholesterol levels in LDL receptor-deficient WHHL rabbits by lowering the VLDL secretion

To examine whether a microsomal triglyceride transfer protein (MTP)-inhibitor is effective in patients with homozygous familial hypercholesterolemia, we administered (2S)-2-cyclopentyl-2-[4-[(2,4-dimethyl-9H-pyrido[2,3-b]indol-9-yl)methyl]phenyl]-N-[(1S)-2-hydroxy-1-phenylethyl]ethanamide (Implitapide), a new MTP inhibitor, to low-density lipoprotein (LDL)-receptor-deficient Watanabe heritable hyperlipidemic (WHHL) rabbits at doses of 3, 6, and 12 mg/kg for 4 weeks. In the 12 mg/kg group, the plasma cholesterol and triglyceride levels were decreased by 70% and 45%, respectively, and the very low-density lipoprotein (VLDL) secretion rate was decreased by 80%. The composition of newly secreted VLDL was similar in each group. This suggests that Implitapide diminished the number of VLDL particles secreted from the liver. Although the ratio of vitamin E/LDL was not altered by Implitapide, triglyceride accumulation and a decrease in vitamin E were observed in the liver. In conclusion, an inhibition of VLDL secretion led to a decrease of plasma LDL in WHHL rabbits, and MTP inhibitors should have hypolipidemic effects against homozygous familial hypercholesterolemia.

Foam cell formation containing lipid droplets enriched with free cholesterol by hyperlipidemic serum

A monoclonal antibody, ASH1a/256C (256C), which binds to atherosclerotic lesions in Watanabe heritable hyperlipidemic rabbit (WHHL) aorta in vivo, recognizes complex structures of phosphatidylcholine mixed with neutral lipids. In the present study, a cell culture system is described in which foam cells express 256C-positive lipid droplets. J774.1 macrophages were incubated in the presence of a small volume of WHHL serum for 24 h to produce foam cells, which were then incubated without the WHHL serum for 3 days. Oil red O-positive lipid droplets appeared on day 1, and were present in the cells during the whole incubation period. The lipid droplets in the cells were positively immunostained with antibody 256C on day 4, although they were negative on day 1. Expression of the antigenic lipid droplets was also induced by the addition of acetylated LDL or sera from patients with hyperlipidemia. When foam cells were induced by the addition of WHHL serum, cellular content of cholesteryl ester was greatly increased but then decreased to near basal levels by day 4. Concomitantly, cellular free cholesterol increased during the culture period, indicating that the cholesteryl ester changes to free cholesterol by day 4. The lipid droplets in the foam cells on day 4 were positively stained with filipin, a fluorescent probe for free cholesterol, as well as with 256C antibody, indicating that free cholesterol is enriched in antigenic lipid droplets. These observations suggest that hydrolysis and rearrangement of cellular cholesterol take place in foam cells to form complex structures of phosphatidylcholine and free cholesterol in lipid droplets.

Heme oxygenase-1 inhibits atherogenesis in Watanabe heritable hyperlipidemic rabbits

BACKGROUND

Heme oxygenase-1 (HO-1) is proposed to have a variety of adaptive responses against oxidative stress. To examine the function of HO-1 against atherogenesis in vivo, we observed the effects of HO-1 inhibition on atherosclerotic lesion formation in Watanabe heritable hyperlipidemic rabbits (WHHL). Methods and Results- During 4 weeks of a 1% cholesterol diet, intravenous injections of Sn-protoporphyrin IX to inhibit HO-1 (S group, n=10) and saline as a control (C group, n=10) were given to 3-month-old WHHL rabbits. The percentages of en face atherosclerotic lesion areas in total descending aorta by Sudan IV staining (EFA) and the ratio of intima to media in microscopic atherosclerotic lesions in the ascending aortas (I/M) were calculated. Two different quantitative methods revealed significantly greater atherosclerotic lesions in the S group than the C group (EFA, P<0.001; I/M, P<0.005). HO-1 expression in atherosclerotic lesions was confirmed by Northern blot and immunohistochemical analyses. The dominant cell types expressing HO-1 were macrophages and foam cells, in which oxidized phospholipids were also accumulated. HO inhibition increased plasma and tissue lipid peroxide levels without affecting plasma lipid co osition.

CONCLUSIONS

These results suggest the possibilities that HO-1 has antiatherogenic properties in vivo and that the antiatherogenic properties of HO-1 are conducted through the prevention of lipid peroxidation.

Arteriosclerosis in the influx and intravisceral arteries of the liver, kidney and lung of WHHL rabbits

We performed a histopathological investigation on arteriosclerotic development in the influx and intravisceral arteries of the liver, kidney and lung of male WHHL rabbits. In the influx arteries of these organs, we observed severe atherosclerotic vascular lesions with high-grade luminal stenosis. In the intravisceral arteries of the liver and kidney, no arteriosclerotic lesions were observed. However, in the intrapulmonary arteries, we recognized severe atherosclerotic vascular changes with high-grade stenosis or total obstruction of the lumen in some middle to large sized pulmonary arteries. These observations indicate that the development of arteriosclerosis in parenchymatous organs differs, and that some organs are predisposed to arteriosclerosis formation.

Two cases of histopathologically advanced (stage IV) early gastric cancers

We report two cases of early gastric cancer with distant metastases (stage IV). At our institute 1428 cases of primary gastric cancer were resected between 1980 and 1997; 536 were diagnosed as early gastric cancer based on the resected specimens (304 cases of mucosal cancer, Tis--TNM classification--and 232 of submucosal cancer, T1). 528 of these 536 cases were classified as histological stage I, six as stage II, none as stage III and two as stage IV. The incidence of stage IV early gastric cancer was 0.14% of all gastric cancers and 0.37% of the early gastric cancers. The two patients with stage IV early gastric cancer were women. Both tumors were defined as early cancer because they were confined to the submucosa. One was a type 0 IIc + III early cancer, histologically classifiable as a small, moderately differentiated adenocarcinoma (tub2 according to the Japanese Classification of Gastric Carcinoma, G2; TNM classification: ICD-O C16), size 10 x 8 mm; the other was a surface spreading type 0 IIc, classifiable as a signet-ring cell carcinoma (sig, G3), size 50 x 35 mm. Stage IV factors were N3 in the first and ovarian metastasis (Krukenberg tumor) in the second case.

Cerebral atherosclerosis occurs spontaneously in homozygous WHHL rabbits

We demonstrated that selectively bred homozygous WHHL rabbits known to show hypercholesterolemia and severe coronary atherosclerosis also spontaneously develop cerebral atherosclerosis beginning at 9 months of age. These intracranial lesions occurred in the absence of hypertension in 24 of 25 animals at various sites, mainly along arteries at the base of the brain. No lesions were observed in penetrating arteries. Lesions were rich in smooth muscle cells and fibrous tissue, showing only rare fragmentation or disappearance of the internal elastic lamina, and only limited lipid deposition. Few macrophages were observed in these lesions. No significant correlation was seen between severity of cerebral atherosclerosis and age, systolic blood pressure (BP), serum total cholesterol, or triglyceride concentration. Xanthomas of the pia mater were observed in all 25 rabbits. Arterial findings were similar to those in human cerebral atherosclerosis, indicating that the coronary atherosclerosis-prone homozygous WHHL rabbit represents the first animal model for spontaneous cerebral atherosclerosis.

Fibromuscular cap composition is important for the stability of established atherosclerotic plaques in mature WHHL rabbits treated with statins

We examined the relationship between plaque vulnerability and fibromuscular cap composition using hydrophilic pravastatin and lipophilic fluvastatin. WHHL rabbits aged 10 months were given pravastatin (50 mg/kg) or fluvastatin (20 mg/kg) for 52 weeks. The atherosclerotic lesions were immunohistochemically or conventionally stained and the components were analyzed with a color image analyzer. Compared with the control group, the plasma cholesterol levels were decreased by about 25% in both statin groups. Pravastatin decreased the lipid components (macrophages+extracellular lipids) in whole aortic plaques by 34% and the fibrous caps of coronary plaques by 55%. Fluvastatin decreased the fibromuscular components (smooth muscle cells+collagen fibers) in whole aortic plaques and in the fibromuscular caps of the aortic and coronary plaques. In the pravastatin group, the vulnerability index, the ratio of (lipid components)/(fibromuscular components), was decreased in whole aortic plaques by 28% and in the fibromuscular caps of coronary lesions by 61%, while the indexes were increased in the fluvastatin group. The incidence of vulnerable plaques was decreased by 74% in the coronary plaques of the pravastatin group. Our results suggest that the stability of atheromatous plaques was improved due to a decrease of the lipid components and vulnerability index of the fibromuscular cap by pravastatin.

Effects of high-dose troglitaz one on insulin sensitivity and beta-cell function in Watanabe heritable hyperlipidemic rabbits

To clarify the dose-response effects of troglitazone on insulin sensitivity and beta-cell function, we examined the effects of high-dose troglitazone (100 mg/day per animal, administered as a food admixture) on glucose and insulin metabolism in hyperinsulinemic Watanabe heritable hyperlipidemic (WHHL) rabbits, and compared the results with our previous results with low-dose troglitazone (10 mg /day per animal).

MATERIALS AND METHODS

Glucose and insulin metabolism were quantitatively characterized by a minimal model technique as reported previously.

RESULTS

When troglitazone was administrated at a high dose for 6 months, it reduced hyperinsulinemia as reflected by a reduced basal (steady-state) insulin concentration lb and the insulin response to a glucose load, improved beta-cell function as reflected by decreased second-phase post-hepatic insulin delivery to glucose phi2, and reduced insulin resistance as reflected by increased insulin sensitivity to glucose disposal Si, without affecting glucose tolerance as reflected by an unchanged rate of glucose utilization Kg or insulin-independent glucose disposal Sg. The reductions in Ib and phi2 and the increases in Si in WHHL rabbits treated with a high dose of troglitazone were greater (p<0.05) than those observed in WHHL rabbits treated with a low dose of troglitazone, as assessed by a two-way repeated measures analysis of variance and the Wilcoxon-Mann-Whitney test.

CONCLUSION

In WHHL rabbits, troglitazone dose-dependently reduced hyperinsulinemia, improved beta-cell function, and increased insulin sensitivity.

Hepatocellular carcinoma with biliary tumor thrombi: aggressive operative approach after appropriate preoperative management

BACKGROUND

The aim of this study was to clarify clinicopathologic characteristics of, and to evaluate an aggressive treatment strategy for, hepatocellular carcinoma with biliary tumor thrombi.

METHODS

From 1980 to 1999, a total of 132 patients underwent hepatectomy for hepatocellular carcinoma. Of these, 17 patients had macroscopic biliary tumor thrombi and were retrospectively analyzed.

RESULTS

The operative procedures included right hepatic trisegmentectomy (n = 1), right or left hepatic lobectomy (n = 11), and segmentectomy or subsegmentectomy (n = 5). In 13 patients, tumor thrombi extended beyond the hepatic confluence and was treated by thrombectomy through a choledochotomy in 8 patients and extrahepatic bile duct resection and reconstruction in 5 patients. The 3- and 5-year survival rates were 47% and 28%, respectively, with a median survival time of 2.3 years. These survival rates were similar to those achieved in 115 patients without biliary tumor thrombi. In a multivariate analysis, expansive growth type and solitary tumors were independent prognostic variables for favorable outcome after operation, whereas biliary tumor thrombi was not a significant prognostic factor.

CONCLUSIONS

Surgery after appropriate preoperative management of hepatocellular carcinoma with biliary tumor thrombi yields results similar to those of patients without biliary involvement. Hepatectomy with thrombectomy through a choledochotomy appears to be as effective as a resection procedure.

A novel approach to ex vivo gene therapy for familial hypercholesterolemia using human amniotic epithelial cells as a transgene carrier

This study has demonstrated the potential of human amniotic epithelial cells (HAEC) as a transgene carrier to treat patients with familial hypercholesterolemia (FH). One approach to liver-directed gene therapy is represented by transplantation of autologous hepatocytes that have been genetically modified in vitro. However, the hepatocytes must be isolated from surgically resected tissue and it is difficult to expand the hepatocytes in culture. In contrast, the advantages for using HAEC are the higher availability and the nonimmunogenicity after allotransplantation. Our strategy involved isolating HAEC from an amnion, transducing a human low-density lipoprotein receptor (LDLR) gene into these cells with a recombinant adenovirus, and transplanting the genetically modified cells into the liver of an animal model of FH. Each animal, treated with the LDLR-transduced HAEC, exhibited a substantial decrease in serum cholesterol with an eventual return to pretreatment level. Moreover, the transplanted HAEC migrated out of the sinusoids into the hepatic parenchyma and expressed the LDLRs until at least 20 days after transplantation. However, the transplanted HAEC markedly decreased in number after 10 days post-transplant with an increase of inflammatory cells. The temporary nature of the metabolic improvement may be associated with xenograft rejection and transient function of the adenoviral vector.

Serotonin-induced hypercontraction through 5-hydroxytryptamine 1B receptors in atherosclerotic rabbit coronary arteries

BACKGROUND

Augmented vasoconstriction to serotonin (5-hydroxytryptamine [5-HT]) in atherosclerotic vessels plays a crucial role in the development of myocardial ischemia. We investigated mechanisms for serotonin-evoked hypercontraction in atherosclerotic rabbit coronary arteries.

METHODS AND RESULTS

Contractile responses to serotonergic agents of endothelium-denuded coronary arteries from control and Watanabe heritable hyperlipidemic rabbits (WHHL) were examined. WHHL coronary arteries exhibited hypercontraction to 5-HT(1)-receptor agonists; the constrictor threshold concentrations and E:D(50) to serotonin, 5-carboxamidotryptamine, and sumatriptan in WHHL were significantly lower, and the E:(max) in WHHL to these agents were increased 55% to 59% above those of the control. Serotonin-evoked contractions in both groups were inhibited by GR127935 (5-HT(1B/1D) antagonist; 0.1 to 1 nmol/L) and pertussis toxin but not by ketanserin (5-HT(2) antagonist; 0.01 to 1 micromol/L), suggesting that the hypercontraction is most likely mediated by 5-HT(1B/1D) receptors through a pertussis toxin-sensitive pathway. Furthermore, simultaneous measurements of [Ca(2+)](i) and isometric tension of fura-2-loaded arteries revealed that the hypercontraction was concomitant with the augmented elevation of [Ca(2+)](i) in the smooth muscle. The 5-HT(1B) mRNA levels in WHHL coronary arteries increased to 2.5-fold over those in control arteries, whereas neither 5-HT(1D) nor 5-HT(2A) mRNA was detected in either group.

CONCLUSIONS

Atherosclerotic rabbit coronary arteries exhibited the enhancement in contraction and Ca(2+) mobilization in response to serotonin. The 5-HT(1B) receptor, which is upregulated by atherosclerosis, most likely mediates the augmenting effects of serotonin.

Statins alter smooth muscle cell accumulation and collagen content in established atheroma of watanabe heritable hyperlipidemic rabbits

BACKGROUND

Acute coronary syndromes often result from rupture of vulnerable plaques. The collagen content of plaques probably regulates their stability. This study tested whether HMG-CoA reductase inhibitors (statins) alter interstitial collagen gene expression or matrix metalloproteinase (MMP) levels in rabbit atheroma.

METHODS AND RESULTS

We administered equihypocholesterolemic doses of pravastatin (a hydrophilic statin, 50 mg. kg(-1). d(-1), n=9), fluvastatin (a cell-permeant lipophilic statin, 20 mg. kg(-1). d(-1), n=10), or placebo (n=10) to mature Watanabe heritable hyperlipidemic rabbits for 52 weeks. The fluvastatin group achieved a much higher peak plasma concentration (23.7 micromol/L) than did the pravastatin group (1.3 micromol/L) under these conditions. Immunohistochemistry revealed that MMP-1, MMP-3, and MMP-9 expression by macrophages in the intima was lower in both the pravastatin and fluvastatin groups than in the placebo group, whereas there was no difference in macrophage numbers. Numbers of intimal smooth muscle cells (SMCs) (identified by immunohistochemistry) and expression of type I procollagen mRNA (detected by in situ hybridization), however, were significantly higher in the pravastatin group than in the fluvastatin group. Treatment with pravastatin, but not fluvastatin, preserved interstitial collagen content in vivo (detected by picrosirius red polarization). In vitro, fluvastatin, but not pravastatin, decreased numbers of rabbit and human aortic SMCs without altering procollagen I mRNA expression.

CONCLUSIONS

This study showed that statins can reduce MMP expression in atheroma and that cell-permeant statins can decrease SMC number and collagen gene expression in vivo.

Gene expression analysis in colorectal cancer using practical DNA array filter

PURPOSE

We examined the usability of a newly developed, compact-sized DNA array filter for studying the gene expression pattern of individual colorectal cancer.

METHODS

Complementary DNA probes were prepared from mRNA extracted from colonic cancer specimens and adjacent normal mucosa and then were labeled with chemiluminescence. These labeled probes were allowed to bind to the gene fragments on the filter. A specialized scanning charge-coupled device camera measured the intensity of each chemiluminescent spot, which is an indicator of the degree to which a specific gene is expressed. Gene expression image was quantified into intensity of signals by using computer software.

RESULTS

Characteristic gene expression patterns were obtained from the colonic cancer cell line, RPMI4788, and the leukemia cell line, HL60, by using this compact-sized DNA array filter in the preliminary experiment. Up-regulation of nm23, TIMP1, VEGF, and cyclin E and down-regulation of some tumor suppressor genes (p53, TOSO, and SIVA), beta-catenin, and metallothionein were observed in colonic cancer specimen when compared with those of normal mucosa.

CONCLUSIONS

We have obtained unique gene expression patterns from colorectal cancer and normal tissue by using a newly developed compact-sized DNA array filter system. Collecting, storing, and analyzing of gene expression data from many samples of colorectal cancer will enable us to identify distinct subsets of patients based on molecular characteristics in the near future.