Cyclooxygenase regulates angiogenesis induced by colon cancer cells

To explore the role of cyclooxygenase (COX) in endothelial cell migration and angiogenesis, we have used two in vitro model systems involving coculture of endothelial cells with colon carcinoma cells. COX-2-overexpressing cells produce prostaglandins, proangiogenic factors, and stimulate both endothelial migration and tube formation, while control cells have little activity. The effect is inhibited by antibodies to combinations of angiogenic factors, by NS-398 (a selective COX-2 inhibitor), and by aspirin. NS-398 does not inhibit production of angiogenic factors or angiogenesis induced by COX-2-negative cells. Treatment of endothelial cells with aspirin or a COX-1 antisense oligonucleotide inhibits COX-1 activity/expression and suppresses tube formation. Cyclooxygenase regulates colon carcinoma-induced angiogenesis by two mechanisms: COX-2 can modulate production of angiogenic factors by colon cancer cells, while COX-1 regulates angiogenesis in endothelial cells.

Clinical implications of the 'no reflow' phenomenon. A predictor of complications and left ventricular remodeling in reperfused anterior wall myocardial infarction

BACKGROUND

Recent studies demonstrated that the "no reflow" phenomenon after coronary reflow implies the presence of advanced myocardial damage. In this study, we verified the prognostic value of the detection of this phenomenon by studying complications, left ventricular morphology, and in-hospital survival after acute myocardial infarction (AMI).

METHODS AND RESULTS

The study population consisted of 126 patients with a first anterior AMI. All patients received coronary reflow within 24 hours of onset of symptoms and underwent myocardial contrast echocardiography (MCE) before and shortly after coronary reflow with an intracoronary injection of sonicated microbubbles. From contrast reperfusion patterns, patients were divided into two subsets: those with MCE no reflow (47 patients, 37%) and those with MCE reflow (79 patients). There was no difference in the frequency of arrhythmia or coronary events between the two subsets. Pericardial effusion and early congestive heart failure were observed more frequently in patients with MCE no reflow than in those with MCE reflow (26% versus 4%, P < .05; 45% versus 15%, P < .05, respectively). Congestive heart failure tended to be prolonged in those with MCE no reflow, and 3 patients (7%) of this subset died of pump failure. Left ventricular end-diastolic volume progressively increased in the convalescent stage in patients with MCE no reflow (early versus late, 145 +/- 43 versus 169 +/- 60 mL, P < .001), whereas it decreased in those with MCE reflow (154 +/- 42 versus 144 +/- 44 mL, P < .01).

CONCLUSIONS

The substantial size of the MCE no reflow phenomenon at coronary reflow conveys useful information about an outcome of coronary intervention and left ventricular remodeling in individual patients with anterior wall AMI, although these are suggestive results in a limited number of patients.

Vagally mediated heart rate recovery after exercise is accelerated in athletes but blunted in patients with chronic heart failure

OBJECTIVES

Vagally mediated heart rate recovery after exercise was assessed in patients with chronic heart failure and in well trained athletes by analyzing the postexercise heart rate decay.

BACKGROUND

Vagal reactivation is an important cardiac deceleration mechanism after exercise. However, alterations of this mechanism under pathologic conditions have not been characterized because of the lack of a specific index.

METHODS

To find a vagally mediated component of heart rate recovery, the time constants of the beat-by-beat heart rate decay for the first 30 s (T30) and the first 120 s (T120) after exercise were obtained at six levels of exercise in eight normal volunteers: 1) at maximal exercise, 2) at anaerobic threshold, 3) at anaerobic threshold with propranolol administration, 4) at anaerobic threshold with atropine administration, 5) at anaerobic threshold with concomitant administration of both drugs, and 6) at 50% of anaerobic threshold. To investigate the effects of heart failure and endurance training on vagally mediated heart rate recovery, T30 and T120 at anaerobic threshold were obtained in 20 patients with chronic heart failure and in 9 cross-country skiers.

RESULTS

In normal volunteers, T30 and T120 were markedly prolonged by atropine administration, indicating that both time constants are mediated by vagal reactivation. Moreover, T30 was almost independent of the exercise intensity and sympathetic blockade, whereas T120 was affected by sympathetic nerve activity and exercise work load. These results indicate that T30 is mediated primarily by vagal reactivation, independent of sympathetic withdrawal, and is significantly smaller in athletes (p < 0.01) and significantly larger in patients with chronic heart failure (p < 0.01) than that in respective age-matched normal control subjects.

CONCLUSIONS

The T30 value could be a specific index for vagally mediated heart rate recovery. Vagally mediated heart rate recovery after exercise is accelerated in well trained athletes but blunted in patients with chronic heart failure.

Noninvasive evaluation of pulmonary hypertension by a pulsed Doppler technique

We used a pulsed Doppler technique to examine the flow velocity pattern in the right ventricular outflow tract in 33 adults. In the patients with normal pulmonary artery pressure (mean pressure less than 20 mm Hg, 16 patients), ejection flow reached a peak level at midsystole (137 +/- 24 msec, mean +/- SD), producing a domelike contour of the flow velocity pattern during systole. In contrast, the flow velocity pattern in patients with pulmonary hypertension (mean pressure greater than or equal to 20 mm Hg, 17 patients) was demonstrated to accelerate rapidly and to reach a peak level sooner (97 +/- 20 msec, p less than .01); in 10 of the pulmonary hypertensive patients a secondary slower rise in flow velocity was observed during a deceleration, resulting in the midsystolic notching. The time to peak flow (acceleration time, AcT) and right ventricular ejection time (RVET) were measured from the flow velocity pattern. Either AcT or AcT/RVET decreased with increase in mean pulmonary artery pressure, and a very high correlation (r = -.90) was found between AcT/RVET and log10 (mean pulmonary artery pressure). The use of this technique permitted the noninvasive estimation of the pulmonary artery pressure.

Beneficial effects of antioxidants in diabetes: possible protection of pancreatic beta-cells against glucose toxicity

Oxidative stress is produced under diabetic conditions and possibly causes various forms of tissue damage in patients with diabetes. The aim of this study was to examine the involvement of oxidative stress in the progression of pancreatic beta-cell dysfunction in type 2 diabetes and to evaluate the potential usefulness of antioxidants in the treatment of type 2 diabetes. We used diabetic C57BL/KsJ-db/db mice, in whom antioxidant treatment (N-acetyl-L-cysteine [NAC], vitamins C plus E, or both) was started at 6 weeks of age; its effects were evaluated at 10 and 16 weeks of age. According to an intraperitoneal glucose tolerance test, the treatment with NAC retained glucose-stimulated insulin secretion and moderately decreased blood glucose levels. Vitamins C and E were not effective when used alone but slightly effective when used in combination with NAC. No effect on insulin secretion was observed when the same set of antioxidants was given to nondiabetic control mice. Histologic analyses of the pancreases revealed that the beta-cell mass was significantly larger in the diabetic mice treated with the antioxidants than in the untreated mice. As a possible cause, the antioxidant treatment suppressed apoptosis in beta-cells without changing the rate of beta-cell proliferation, supporting the hypothesis that in chronic hyperglycemia, apoptosis induced by oxidative stress causes reduction of beta-cell mass. The antioxidant treatment also preserved the amounts of insulin content and insulin mRNA, making the extent of insulin degranulation less evident. Furthermore, expression of pancreatic and duodenal homeobox factor-1 (PDX-1), a beta-cell-specific transcription factor, was more clearly visible in the nuclei of islet cells after the antioxidant treatment. In conclusion, our observations indicate that antioxidant treatment can exert beneficial effects in diabetes, with preservation of in vivo beta-cell function. This finding suggests a potential usefulness of antioxidants for treating diabetes and provides further support for the implication of oxidative stress in beta-cell dysfunction in diabetes.

Delayed effects of sublethal ischemia on the acquisition of tolerance to ischemia

The infarct-limiting effect of ischemic preconditioning is believed to be a transient phenomenon. We examined the delayed effects of repetitive brief ischemia on limiting infarct size in an open-chest dog model by an occlusion (90 minutes) of the left anterior descending coronary artery (LAD) followed by reperfusion (5 hours). The dogs were preconditioned with four brief repeated ischemic episodes induced by 5-minute LAD occlusions with subsequent reperfusion. The size of infarcts initiated by a sustained occlusion immediately or 24 hours after preconditioning was significantly smaller when compared with infarcts in sham-operated dogs (for the immediate occlusion, 14.4 +/- 2.0% versus 39.0 +/- 3.7%, respectively [p < 0.01]; and for the delayed occlusion, 18.8 +/- 3.4% versus 35.1 +/- 4.6%, respectively [p < 0.05]); however, when the infarction was induced 3 hours (31.2 +/- 3.7% versus 37.5 +/- 4.2%, respectively) or 12 hours (25.4 +/- 4.8% versus 35.0 +/- 5.3%, respectively) after repetitive ischemia, the infarct size did not differ. No differences were seen in regional myocardial blood flow or rate-pressure products between the two groups. These results indicate that an infarct-limiting effect of brief repeated ischemia can be observed 24 hours after sublethal preconditioning.

Direct association of the gap junction protein connexin-43 with ZO-1 in cardiac myocytes

The gap junction protein connexin-43 is normally located at the intercalated discs of cardiac myocytes, and it plays a critical role in the synchronization of their contraction. The mechanism by which connexin-43 is localized within cardiac myocytes is unknown. However, localization of connexin-43 likely involves an interaction with the cytoskeleton; immunofluorescence microscopy showed that in cardiac myocytes, connexin-43 specifically colocalizes with the cytoskeletal proteins ZO-1 and alpha-spectrin. In transfected HEK293 cells, immunoprecipitation experiments using coexpressed epitope-tagged connexin-43 and ZO-1 indicated that ZO-1 links connexin-43 with alpha-spectrin. The domains responsible for the protein-protein interaction between connexin-43 and ZO-1 were identified using affinity binding assays with deleted ZO-1 and connexin-43 fusion proteins. Immunoblot analysis of associated proteins showed that the C-terminal domain of connexin-43 binds to the N-terminal domain of ZO-1. The role of this linkage in gap junction formation was examined by a dominant-negative assay using the N-terminal domain of ZO-1. Overexpression of the N-terminal domain of ZO-1 in connexin-43-expressing cells resulted in redistribution of connexin-43 from cell-cell interfaces to cytoplasmic structures; this intracellular redistribution of connexin-43 coincided with a loss of electrical coupling. We therefore conclude that the linkage between connexin-43 and alpha-spectrin, via ZO-1, may serve to localize connexin-43 at the intercalated discs, thereby generating functional gap junctions in cardiac myocytes.

Activation of mitogen-activated protein kinases/extracellular signal-regulated kinases in human hepatocellular carcinoma

Mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) is a key molecule in intracellular signal transducing pathways that transport extracellular stimuli from cell surface to nuclei. MAPK/ERK has been revealed to be involved in the physiological proliferation of mammalian cells and also to potentiate them to transform. However, its role in the outgrowth of human hepatocellular carcinoma (HCC) has yet to be clarified. Therefore, in this study, we investigated the activation of MAPK/ERK and its associated gene expression in HCC. MAPK/ERK was activated in 15 of 26 cases of HCC we examined (58%), and its activity level was significantly higher in HCC than in the adjacent non-cancerous lesions. Besides, MAPK/ERK activation in HCC was positively correlated with protein expression of transcription factor c-Fos. Furthermore, in 25 of 26 cases of HCC which genomic DNA was available, 22 cases without genomic DNA amplification exhibited positive correlation, not only between protein expression of c-Fos and cyclin D1, but also between MAPK/ERK activation and cyclin D1 expression. Concerning the relationship between MAPK/ERK activation and the clinicohistopathological features of HCC, the tumor (HCC) versus non-tumor (non-cancerous counterpart) ratio (T/N) of MAPK/ERK activity was positively correlated with tumor size, but neither with the stage of HCC nor the degree of differentiation of HCC. In conclusion, these findings suggest that MAPK/ERK activation in human HCC may play an important role in multistep hepatocarcinogenesis, especially in the progression of HCC; at least in part, through cyclin D1 up-regulation primarily induced by MAPK/ERK via c-Fos.

Diffusion-weighted single-shot echoplanar MR imaging for liver disease

OBJECTIVE

The aims of this study were to determine apparent diffusion coefficients (ADCs) of the abdominal organs and liver lesions, to determine the effect of the magnitude of b values on the ADCs, and to determine whether measured ADCs of liver tumors help differentiate benign from malignant lesions.

SUBJECTS AND METHODS

Six healthy volunteers and 126 patients were examined with diffusion-weighted single-shot echo-planar imaging using multiple b values (maximum, 846 sec/mm2). The ADCs of the liver, spleen, kidney, 49 malignant liver lesions (33 hepatocellular carcinomas, 15 metastatic liver tumors, and one cholangiocellular carcinoma), and 30 benign lesions (17 cysts, 12 hemangiomas, and one angiomyolipoma) were calculated.

RESULTS

The ADCs of the abdominal organs and liver lesions showed smaller values when calculated with the greater maximum b values. The ADCs of the benign lesions calculated with all the b values of less than 850 sec/mm2 (2.49+/-1.39 x 10(-3) mm2/sec) were significantly (p = .0024) greater than those of the malignant lesions (1.01+/-0.38 x 10(-3) mm2/sec). When the maximum b value is 846 sec/mm2, use of a threshold ADC of 1.6 x 10(-3) mm2/sec would result in a sensitivity of 98% and a specificity of 80% for differentiation of malignant liver lesions from benign lesions.

CONCLUSION

Measurement of ADC has good potential for characterizing liver lesions, but the calculated ADCs could be affected by the magnitude of the maximum b value.

Intravenous nicorandil can preserve microvascular integrity and myocardial viability in patients with reperfused anterior wall myocardial infarction

OBJECTIVES

We assessed whether the intravenous administration of nicorandil, an adenosine triphosphate (ATP)-sensitive K+ channel opener, exerts beneficial effect on microvascular function and functional and clinical outcomes in patients with acute myocardial infarction (AMI).

BACKGROUND

Experimental studies documented that ATP-sensitive K+ channel opener exerts cardioprotection after prolonged ischemia.

METHODS

We randomly divided 81 patients with a first anterior AMI into two groups, nicorandil (n = 40) and control groups (n = 41). All patients received successful coronary angioplasty within 12 h after the symptom onset and underwent myocardial contrast echcardiography (MCE) with the intracoronary injection of sonicated microbubbles. In the nicorandil group, we injected 4 mg of nicorandil followed by the infusion at 6 mg/h for 24 h and by oral nicorandil (15 mg/day).

RESULTS

The improvement in regional left ventricular function, wall motion score and regional wall motion was significantly better in the nicorandil group then in the control group. Intractable congestive heart failure, malignant ventricular arrhythmia and pericardial effusion were more frequently found in the control group than in the nicorandil group (15% vs. 37%, 5% vs. 20% and 8% vs. 37%, p < 0.05, respectively). The frequency of sizable MCE no reflow phenomenon was significantly lower in the nicorandil group than in the control group (15% vs. 33%, p < 0.05).

CONCLUSIONS

Intravenous nicorandil in conjunction with coronary angioplasty is associated with better functional and clinical outcomes compared to angioplasty alone in patients with an anterior AMI. Myocardial contrast echocardiography findings imply that an improvement in microvascular function with nicorandil may be attributable to this better outcome.

Frequency-Dependent Natural Selection in the Handedness of Scale-Eating Cichlid Fish

Frequency-dependent natural selection has been cited as a mechanism for maintaining polymorphisms in biological populations, although the process has not been documented conclusively in field study. Here, it is demonstrated that the direction of mouth-opening (either left-handed or right-handed) in scale-eating cichlid fish of Lake Tanganyika is determined on the basis of simple genetics and that the abundance of individuals with left- or right-handedness depends on frequency-dependent natural selection. Attacking from behind, right-handed individuals snatched scales from the prey's left flank and left-handed ones from the right flank. Within a given population, the frequency of the two phenotypes oscillated around unity. This phenomenon was effected through frequency-dependent selection exerted by the prey's alertness. Thus, individuals of the rare phenotype had more success as predators than those of the more common phenotype.

Myocardial perfusion patterns related to thrombolysis in myocardial infarction perfusion grades after coronary angioplasty in patients with acute anterior wall myocardial infarction

BACKGROUND

Epicardial coronary flow is occasionally reduced even after coronary intervention despite the absence of vessel obstruction in patients with acute myocardial infarction. Our aim was to clarify the cause and outcomes of radiocontrast slow filling in patients with reperfused acute anterior myocardial infarction by assessing microvascular damage with the use of myocardial contrast echocardiography (MCE) and functional outcomes.

METHODS AND RESULTS

We carefully reviewed the cineangiograms of 86 patients who achieved coronary revascularization within 12 hours of the onset and underwent MCE before and soon after recanalization with the intracoronary injection of sonicated microbubbles. Antegrade coronary flow after recanalization was graded by two observers based on Thrombolysis in Myocardial Infarction (TIMI) trial flow grades. Left ventricular ejection fraction was measured on the day of infarction and 1 month later. TIMI grade 2 was observed in 18 patients (21%), and the other 68 patients manifested TIMI grade 3 after recanalization. All patients with TIMI 2 showed substantial MCE no reflow, whereas only 11 patients (16%) with TIMI 3 showed MCE no reflow. Functional improvement was worse in patients with TIMI 2 than in those with TIMI 3 (TIMI 2, 38 +/- 8% versus 40 +/- 8%, P = NS [acute versus late]; TIMI 3, 44 +/- 13% versus 55 +/- 13%, P < .001). Among patients with TIMI 3, significant functional improvement was observed only in patients with MCE reflow (MCE reflow, 46 +/- 13% versus 57 +/- 12%, P < .001; MCE no reflow, 35 +/- 11% versus 45 +/- 12%, P = NS).

CONCLUSIONS

Despite no obstructive lesion of the vessel, TIMI 2 is caused by advanced microvascular damage and is a highly specific, although not sensitive, predictor of poor functional outcomes in patients with acute myocardial infarction. TIMI 3 does not necessarily indicate myocardial salvage, and detection of MCE no reflow in these patients is particularly useful for the prediction of functional outcome.

Extensive development of vulnerable plaques as a pan-coronary process in patients with myocardial infarction: an angioscopic study

OBJECTIVES

To test our hypothesis that the development of vulnerable plaques is not limited to the culprit lesions, but is a pan-coronary process, we directly observed all three major coronary arteries by angioscopy and evaluated the prevalence of yellow plaques in patients with myocardial infarction (MI).

BACKGROUND

Although pathologic studies have suggested that the disruption of atheromatous plaque plays a major role in the development of acute MI, the prevalence of yellow plaques in the whole coronary arteries of patients with MI has not been clarified.

METHODS

Thirty-two patients undergoing follow-up catheterization one month after the onset of MI were prospectively and consecutively enrolled in this study. The prevalence of yellow plaques and thrombus in the major coronary arteries was successfully evaluated in 20 patients (58 coronary arteries, 21 culprit lesions) by coronary angioscopy. The diameter stenosis (DS) of the culprit lesions and the maximal diameter stenosis (maxDS) of nonculprit segments were angiographically measured for each coronary artery.

RESULTS

The DS of the culprit lesions and maxDS were 27 +/- 17% and 19 +/- 13%, respectively. Yellow plaques and thrombus were detected in 19 (90%) and 17 (81%) of 21 culprit lesions, respectively. Yellow plaques were equally prevalent in the infarct-related and non-infarct-related coronary arteries (3.7 +/- 1.6 vs. 3.4 +/- 1.8 plaques/artery). However, thrombus was only detected in the nonculprit segments of one (2%) coronary artery.

CONCLUSIONS

In patients with MI, all three major coronary arteries are widely diseased and have multiple yellow though nondisrupted plaques. Acute MI may represent the pan-coronary process of vulnerable plaque development.

Exercise provides direct biphasic cardioprotection via manganese superoxide dismutase activation

Epidemiologic investigations have shown that exercise reduces morbidity and mortality from coronary artery disease. In this study, using a rat model, we attempted to determine whether exercise can reduce ischemic injury to the heart and elucidate a mechanism for the cardioprotective effect of exercise. Results showed that exercise significantly reduced the magnitude of a myocardial infarction in biphasic manner. The time course for cardioprotection resembled that of the change in manganese superoxide dismutase (Mn-SOD) activity. The administration of the antisense oligodeoxyribonucleotide to Mn-SOD abolished the expected decrease in infarct size. We showed that the level of tumor necrosis factor alpha (TNF-alpha) and interleukin 1beta (IL-1beta) increased after exercise. The simultaneous administration of the neutralizing antibodies to the cytokines abolished the exercise-induced cardioprotection and the activation of Mn-SOD. Furthermore, TNF-alpha can mimic the biphasic pattern of cardioprotection and activation of Mn-SOD. An antioxidant completely abolished cardioprotection and the activation of Mn-SOD by exercise or the injection of TNF-alpha as well as exercise-induced increase in TNF-alpha and IL-1beta. The production of reactive oxygen species and endogenous TNF-alpha and IL-1beta induced by exercise leads to the activation of Mn-SOD, which plays major roles in the acquisition of biphasic cardioprotection against ischemia/reperfusion injury in rats.

Parathyroid hormone exerts disparate effects on osteoblast differentiation depending on exposure time in rat osteoblastic cells

It has been reported that PTH exerts bone-forming effects in vivo when administered intermittently. In the present study, the anabolic effects of PTH(1-34) on osteoblast differentiation were examined in vitro. Osteoblastic cells isolated from newborn rat calvaria were cyclically treated with PTH(1-34) for the first few hours of each 48-h incubation cycle. When osteoblastic cells were intermittently exposed to PTH only for the first hour of each 48-h incubation cycle and cultured for the remainder of the cycle without the hormone, osteoblast differentiation was inhibited by suppressing alkaline phosphatase activity, bone nodule formation, and mRNA expression of alkaline phosphatase, osteocalcin, and PTH/PTHrP receptor. Experiments using inhibitors and stimulators of cAMP/protein kinase A (PKA) and Ca2+/PKC demonstrated that cAMP/PKA was the major signal transduction system in the inhibitory action of PTH. In contrast, the intermittent exposure to PTH for the first 6 h of each 48-h cycle stimulated osteoblast differentiation. Both cAMP/ PKA and Ca2+/PKC systems appeared to be involved cooperatively in this anabolic effect. Continuous exposure to PTH during the 48-h incubation cycle strongly inhibited osteoblast differentiation. Although both cAMP/PKA and Ca2+/PKC were involved in the effect of continuous exposure to PTH, they appeared to act independently. A neutralizing antibody against IGF-I blocked the stimulatory effect on alkaline phosphatase activity and the expression of osteocalcin mRNA induced by the 6-h intermittent exposure. The inhibitory effect induced by the 1-h intermittent exposure was not affected by anti-IGF-I antibody. These results suggest that PTH has diverse effects on osteoblast differentiation depending on the exposure time in vitro mediated through different signal transduction systems. These in vitro findings explain at least in part the in vivo action of PTH that varies with the mode of administration.

Neurogenesis by progenitor cells in the ischemic adult rat hippocampus

BACKGROUND AND PURPOSE

Recently, there has been great interest in adult neurogenesis. We investigated whether transient forebrain ischemia could influence the proliferation of neuronal progenitor in the subgranular zone (SGZ) of the rat hippocampus and whether aging could influence the neurogenesis after ischemia.

METHODS

Male Wistar rats were subjected to 4-vessel occlusion model. We used a bromodeoxyuridine (BrdU) labeling method to identify the postproliferation cells and double-immunostaining with confocal microscopy to determine the cell phenotype.

RESULTS

The number of BrdU-positive cells in the SGZ increased approximately 5.7-fold 8 days after ischemia, compared with the control. BrdU-positive cells formed clusters, which suggested that these cells had divided from an original progenitor cell, and expressed Musashi1 (Msi1), a marker of neural stem/progenitor cells. Although astrocytes also expressed Msi1 in the adult brain, Msi1-positive cells that formed clusters in the SGZ did not express glial fibrillary acidic protein, an astrocyte marker. About 70% of all BrdU-positive cells in the SGZ represented the neuronal phenotype 4 weeks after the BrdU injection. Although proliferation of progenitor cells was stimulated in both young and older animals, aging accelerated the reduction in newborn cells after ischemia.

CONCLUSIONS

Our results indicate that ischemic stress stimulated the proliferation of neuronal progenitor cells in the SGZ of both young and old rats but resulted in increased neurogenesis only in young animals. Our findings will be important in developing therapeutic intervention to enhance endogenous neurogenesis after brain injury.

Inactivation of glutathione peroxidase by nitric oxide. Implication for cytotoxicity

S-nitro-N-acetyl-DL-penicillamine (SNAP), a nitric oxide (NO) donor, inactivated bovine glutathione peroxidase (GPx) in a dose- and time-dependent manner. The IC50 of SNAP for GPx was 2 microM at 1 h of incubation and was 20% of the IC50 for another thiol enzyme, glyceraldehyde-3-phosphate dehydrogenase, in which a specific cysteine residue is known to be nitrosylated. Incubation of the inactivated GPx with 5 mM dithiothreitol within 1 h restored about 50% of activity of the start of the SNAP incubation. A longer exposure to NO donors, however, irreversibly inactivated the enzyme. The similarity of the inactivation with SNAP and reactivation with dithiothreitol of GPx to that of glyceraldehyde-3-phosphate dehydrogenase, suggested that NO released from SNAP modified a cysteine-like essential residue on GPx. When U937 cells were incubated with 100 microM SNAP for 1 h, a significant decrease in GPx activity was observed although the change was less dramatic than that with the purified enzyme, and intracellular peroxide levels increased as judged by flow cytometric analysis using a peroxide-sensitive dye. Other major antioxidative enzymes, copper/zinc superoxide dismutase, manganese superoxide dismutase, and catalase, were not affected by SNAP, which suggested that the increased accumulation of peroxides in SNAP-treated cells was due to inhibition of GPx activity by NO. Moreover, stimulation with lipopolysaccharide significantly decreased intracellular GPx activity in RAW 264.7 cells, and this effect was blocked by NO synthase inhibitor N omega-methyl-L-arginine. This indicated that GPx was also inactivated by endogenous NO. This mechanism may at least in part explain the cytotoxic effects of NO on cells and NO-induced apoptotic cell death.

Hypervascular hepatocellular carcinoma: detection with double arterial phase multi-detector row helical CT

PURPOSE

To assess whether double arterial phase imaging with multi-detector row helical computed tomography improves detection of hypervascular hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Fifty-one patients with 96 hypervascular HCCs underwent double arterial phase imaging of the entire liver. At measured delay after intravenous administration of 2 mL/kg of contrast medium at a rate of 5 mL/sec, the early and late arterial phase images were obtained serially during a single breath hold with interscan delay of 5.0 seconds. Detector row configuration of 2.5 x 4 mm, pitch of 6, and scanning time of 10.5 seconds for each phase were used. Forty 5-mm-thick reconstruction images were obtained for each phase. Each image set was interpreted separately by three observers, who were unaware of tumor burden in the liver, to detect hypervascular HCC. Sensitivity, positive predictive value, and area below the receiver operating characteristic curve (A(z)) for early and late arterial phases separately and together were calculated.

RESULTS

Mean sensitivity and positive predictive value for hypervascular HCC were 54% and 85% for the early arterial phase, 78% and 83% for the late arterial phase, and 86% and 92% for the double arterial phase, respectively. Double arterial phase imaging showed significantly superior sensitivity compared with early or late arterial phase imaging alone for detecting HCC (P <.05). The mean A(z) value for double arterial phase was significantly higher than that for early or late arterial phase imaging alone (P <.05). Double arterial phase imaging showed the lowest number of false-positive lesions.

CONCLUSION

Double arterial phase imaging is recommended to improve detection of hypervascular HCCs and reduce false-positive lesions.

Contribution of microglia/macrophages to expansion of infarction and response of oligodendrocytes after focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

The purpose of this study was (1) to examine the contribution of microglia and macrophages with their interleukin-1beta production and (2) to assess the vulnerability and response of oligodendrocytes in cerebral infarction.

METHODS

Male Wistar rats were subjected to permanent occlusion of the left middle cerebral artery. Expansion of ischemic infarction and response of oligodendrocytes were investigated together with accumulation of inflammatory cells, production of interleukin-1beta, and disruption of the blood-brain barrier. Apoptotic cell death was inferred from fragmented DNA and the expression of proapoptotic Bax protein.

RESULTS

During expansion of infarction, amoeboid microglia and extravasation of serum albumin were observed not only in the infarcted area but also in the adjacent surviving area, whereas macrophages accumulated along the boundary and granulocytes migrated into the center of the infarction. Both amoeboid microglia and macrophages produced interleukin-1beta, an inflammatory cytokine, during an early ischemic period. Furthermore, macrophages within the infarcted tissue expressed Bax protein and subsequently showed fragmented nuclear DNA. Oligodendrocytes were detected in the infarcted area even after 24 hours following middle cerebral artery occlusion, but they subsequently developed fragmented DNA. A week after onset of ischemia, oligodendrocytes were found to be accumulated in the intact area bordered with the infarct together with reactive astrocytes.

CONCLUSIONS

Our results suggest the importance of amoeboid microglia, macrophages, and their interleukin-1beta production in gradual expansion of cerebral infarction. Resident oligodendrocytes may be resistant to ischemic insults, and oligodendrocytes accumulated at the border of the infarction may participate in tissue repair after cerebral infarction.

Cerebral ischemia after bilateral carotid artery occlusion and intraluminal suture occlusion in mice: evaluation of the patency of the posterior communicating artery

Cerebral ischemia models using mice have drawn increasing attention, particularly because of the availability of transgenic animals. However, the variability of intracranial vasculature at the circle of Willis in mice can influence the degree of ischemia in both the bilateral common carotid artery (CCA) occlusion and intraluminal suture occlusion models. We have developed a method to predict the extent of the anastomosis between carotid and vertebrobasilar circulation in three mouse strains (C57BL/6, CBA, and DBA/2) by measuring cortical microperfusion with laser Doppler flowmetry during a 1-minute occlusion of both CCA. When animals showed residual cortical microperfusion of less than 12% during bilateral CCA occlusion, the mice showed absence of functional anastomosis, developed ATP depletion in the frontal cortex during occlusion, and had ischemic neuronal death in the hippocampus and caudoputamen after occlusion for 15 minutes and recirculation for 7 days. Furthermore, those mice exhibited decreased local cerebral blood flow and associated ischemic neuronal death in the hippocampus, within the territory supplied by the posterior cerebral artery, with the intraluminal suture occlusion model. The current study demonstrates the need for assessment of intracranial vasculature in each animal by measuring cortical microperfusion during temporary occlusion of both CCA, no matter whether cerebral ischemia is produced by bilateral CCA occlusion or intraluminal suture occlusion in transgenic mice.

Beneficial effect of intracoronary verapamil on microvascular and myocardial salvage in patients with acute myocardial infarction

OBJECTIVES

We assessed the acute effect of intracoronary injection of verapamil on microvascular function after primary percutaneous translumanal coronary angioplasty (PTCA) for acute myocardial infarction (AMI) with myocardial contrast echocardiography (MCE) in relation to functional outcomes.

BACKGROUND

Recent clinical studies have documented the potential of verapamil for possible increase in coronary blood flow after primary PTCA.

METHODS

Forty patients with a first AMI were randomly assigned to the verapamil group (n = 20) or the control group (n = 20). In the verapamil group, verapamil (0.5 mg) was injected into the infarct-related artery shortly after PTCA, followed by the oral administration. We performed MCE with an intracoronary injection of sonicated microbubbles before and after verapamil. To assess microvascular integrity, we determined the baseline-subtracted peak intensity in the risk area and the ratio of the no reflow zone plus the low reflow zone to the risk area (low reflow ratio). We determined the average wall motion score (dyskinesia/akinesia = 3; normal = 0) in the risk area on the day of AMI and a mean of 24 days later.

RESULTS

The low reflow zone was observed shortly after PTCA in 14 verapamil group patients, and the low reflow ratio decreased after verapamil (0.39 +/- 0.23 vs. 0.29 +/- 0.17 [mean +/- SD], p < 0.05). Peak intensity significantly (p < 0.05) increased from 6 +/- 5 to 12 +/- 6 after verapamil. The reduction in wall motion score from the acute (day -1) to the late stage (day -24) was significantly greater in the verapamil group than in the control group (0.7 +/- 0.8 vs. 0.2 +/- 1.3, respectively, p < 0.05).

CONCLUSIONS

Intracoronary administration of verapamil after primary PTCA can attenuate microvascular dysfunction and thereby augment myocardial blood flow in patients with AMI, leading to better functional outcome than with PTCA alone.

Cyclooxygenase-2 overexpression enhances lymphatic invasion and metastasis in human gastric carcinoma

OBJECTIVE

Recent epidemiological studies indicate that there is reduced risk of all digestive carcinomas in patients who regularly take nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin. Cyclooxygenase (COX) is a target enzyme for NSAIDs. We investigated the role of two isoforms, COX-1 and COX-2, in the development and metastasis of gastric carcinoma.

METHODS

Fifteen gastric carcinoma tissue specimens and accompanying adjacent mucosa specimens were obtained from surgical resections. COX-1 and COX-2 protein expression were evaluated using Western blotting analysis, and their relative band densities were semi quantified using standard densitometry scanning techniques.

RESULTS

Compared with paired noncancerous specimens, COX-2 was overexpressed in 10 of 15 carcinoma tissue specimens (66.7%). Overall, COX-2 levels in carcinoma tissue were significantly higher. Two early carcinomas (confined to the mucosa and submucosa) and three of 13 advanced carcinomas (extended below the submucosa into the muscular wall) had weak or similar COX-2 expression in paired tissue specimens. COX-2 overexpression in tumors significantly correlated with tumor invasion into the lymphatic vessels in the gastric wall and metastasis to the lymph nodes. Furthermore, the stage grouping in the TNM classification significantly correlated with COX-2 overexpression. In contrast, COX-2 overexpression did not correlate with histopathological grading, surface size, and venous vessel invasion of the tumors. COX-1 levels were similar between paired tissues.

CONCLUSION

COX-2 overexpression might enhance lymphatic invasion and metastasis in patients with gastric carcinoma, implicating a poor prognosis. Therefore, the use of COX-2-specific inhibitor to suppress lymphatic metastasis in humans should be investigated.

Cardiovascular effect of normalizing the hematocrit level during erythropoietin therapy in predialysis patients with chronic renal failure

The optimal target hematocrit (Ht) level in recombinant human erythropoietin (rHuEPO) therapy remains controversial and has hardly been investigated in predialysis patients. We prospectively studied the regression of left ventricular hypertrophy (LVH) on echocardiography in nine predialysis patients with chronic renal failure after a partial correction (target Ht, 30%) and normalization (target Ht, 40%) of the Ht with rHuEPO treatment. Twenty-four-hour ambulatory blood pressure monitoring was also performed. The administration of rHuEPO significantly increased Ht to the target values. The rate of renal failure progression did not change during rHuEPO treatment for 12 months (Cr, from 6.2 +/- 2.0 to 5.5 +/- 2.1 mg/dL). The left ventricular mass index (LVMI) tended to decrease after a partial correction of anemia (Ht, 32.1% +/- 1.8%) at 4 months, whereas it tended to significantly decrease after normalization of Ht (Ht, 39.1% +/- 2.4%) at 12 months (baseline, 140.6 +/- 12.1 g/m2; partial correction, 126.9 +/- 10.0 g/m2; normalization, 111.2 +/- 8.3 g/m2). All patients had received antihypertensive medication before rHuEPO administration, and additional drugs were also required in four cases during the study. As a result, a good overall blood pressure control was obtained without any adverse effects on the circadian blood pressure rhythm. In conclusion, from the perspective of LVH regression, the normalization of Ht was found to be more effective than that associated with a partial correction of anemia during rHuEPO therapy.