Small molecular weight heat shock-related protein, HSP20, exhibits an anti-platelet activity by inhibiting receptor-mediated calcium influx

We have shown that Hsp20, one of small molecular weight heat shock protein, which is present at a high concentration both in vascular smooth muscle cells and in circulating blood in patient with vascular disease, strongly inhibits platelet aggregation in vitro and ex vivo. To clarify the mechanism, we investigated the effect of Hsp20 on free calcium concentration in human platelet cytoplasm using fura 2. Hsp20 inhibited thrombin-induced calcium influx without affecting calcium release from intracellular calcium stores. The degree of inhibition is well-correlated with that of suppression of thrombin-induced platelet aggregation by this substance. Hsp20 also inhibited the elevation of cytoplasmic free calcium level triggered by collagen, but not that by A-23187. In contrast, Hsp28, another type of small molecular weight Hsp, failed to affect the cytoplasmic free calcium level. These findings suggest that Hsp20 inhibits the receptor-mediated calcium influx of platelets without affecting calcium release from intracellular calcium stores, leading to its anti-platelet activity.

Involvement of arachidonic acid in chemical stress-induced interleukin-6 synthesis in osteoblast-like cells: comparison with heat shock protein 27 induction

In a previous study, we have demonstrated that sodium arsenite (arsenite) as chemical stress stimulates heat shock protein 27 (HSP27) induction and arachidonic acid release in osteoblast-like MC3T3-E1 cells, and that the response of HSP27 induction is coupled with metabolic activity of the arachidonic acid cascade. In the present study, we examined the effect of exposure to arsenite on the synthesis of interleukin-6 (IL-6) in these cells. Arsenite induced the synthesis of IL-6 after 6 h from the stimulation up to 48 h. The effect of arsenite on IL-6 synthesis was dose-dependent in the range between 10 and 500 microM. The arsenite-induced IL-6 synthesis was enhanced by the pretreatment with indomethacin, an inhibitor of cyclooxygenase. Nordihydroguaiaretic acid, a lipoxygenase inhibitor, significantly amplified the arsenite-induced IL-6 synthesis. Melittin, an activator of phospholipase A2, which by itself hardly affected the levels of IL-6, markedly enhanced the arsenite-induced IL-6 synthesis. These results strongly suggest that chemical stress induces IL-6 synthesis in osteoblasts, and that the IL-6 synthesis is coupled to the arachidonic acid cascade as well as the HSP27 induction by arsenite.

DNA fragmentation in the CA2 sector of gerbil hippocampus following transient forebrain ischemia

It has been reported that following transient forebrain ischemia in the gerbil, "delayed neuronal death" and "reactive change" occur in hippocampal CA1 and CA2 sectors, respectively. In the present study, using the gerbil transient forebrain ischemia model, we examined brain sections after various recirculation periods and demonstrated, employing the in situ nick-end labeling (TUNEL) method, a nuclear DNA fragmentation in the damaged CA2 neurons.

Tumor necrosis factor-alpha-mediated signal transduction in human neutrophils: involvement of sphingomyelin metabolites in the priming effect of TNF-alpha on the fMLP-stimulated superoxide production

We investigated the mechanism underlying the priming effect of TNF-alpha on fMLP-stimulated superoxide production in human neutrophils. TNF-alpha enhanced fMLP-stimulated superoxide production in a concentration-dependent manner. TNF-alpha also induced sphingomyelin (SM) hydrolysis and increased the formation of its metabolite, sphingosine-1-phosphate (SP-1-P). The treatment of neutrophils with sphingomyelinase also resulted in a similar priming effect. C2 ceramide produced a concentration-dependent inhibition of fMLP-stimulated superoxide production within the concentration range of 1-30 microM. Sphingosine had a dual effect on fMLP-stimulated superoxide generation, exhibiting a priming effect at lower concentrations (0.2-1 microM), but an inhibitory effect at higher concentrations (1-30 microM). SP-1-P (1-30 microM), showed a concentration-dependent enhancement of fMLP stimulated superoxide production. Furthermore, after treating neutrophils with DL-threo-dihydro-sphingosine, a competitive inhibitor of sphingosine kinase, TNF-alpha produced a similar dual effect as observed with sphingosine. These results strongly suggest that SM hydrolysis plays a key role in the intracellular signal transduction mediating the TNF-alpha-mediated priming effect.

Increase of fragmented DNA transport in apical dendrites of gerbil CA1 pyramidal neurons following transient forebrain ischemia by mild hypothermia

Mild hypothermia (38 degrees C) accelerated transport of fragmented DNA in apical dendrites of the gerbil CA1 pyramidal neurons and increased dendrite-terminal fragmented DNA pooling in the apoptotic process following transient forebrain ischemia. The specific DNA fragmentation after the ischemic insult in gerbil hippocampus was examined by in situ nick-end-labeling method, and fluorescence DNA detection technique by DAPI was also performed. There is a precise temperature dependence for the migration of fragmented DNA from nuclei into apical dendrites of CA1 pyramidal cells during apoptosis following transient forebrain ischemia. Increase of fragmented DNA pooling is highly temperature sensitive, occurring at 38 degrees C, while at 39 degrees C there is a marked decrease in DNA pooling.

p38 MAP kinase is required for vasopressin-stimulated HSP27 induction in aortic smooth muscle cells

We previously showed that arginine vasopressin (AVP) stimulates heat shock protein 27 (HSP27) induction through protein kinase C activation in aortic smooth muscle A10 cells. In the present study, we examined whether the mitogen-activated protein (MAP) kinase superfamily is involved in the AVP-stimulated HSP27 induction in A10 cells. AVP stimulated the phosphorylation of p42/p44 MAP kinase and p38 MAP kinase. On the contrary, AVP had little effect on SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase) phosphorylation. The HSP27 accumulation by AVP was not affected by PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. SB203580 and PD169316, specific inhibitors of p38 MAP kinase, suppressed the AVP-induced accumulation of HSP27. 12-O-tetradecanoylphorbol 13-acetate, an activator of protein kinase C, induced accumulation of HSP27 and was not inhibited by PD98059 but was inhibited by SB203580. Calphostin C and ET-18-OCH(3), inhibitors of protein kinase C, reduced the phosphorylation of p38 MAP kinase by AVP. SB203580 and PD169316 suppressed the AVP-increased levels in mRNA for HSP27. Dissociation of the aggregated HSP27 to the dissociated HSP27 was induced by AVP. These results strongly suggest that p38 MAP kinase takes part in the pathway of the AVP-stimulated induction of HSP27 in vascular smooth muscle cells.

Measurement of furancarboxylic acid, a candidate for uremic toxin, in human serum, hair, and sweat, and analysis of pharmacological actions in vitro

3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), a candidate for uremic toxin, was measured in human hair for examining a possible utility as indicator of renal dysfunction. The serum concentration of CMPF was much higher (32.3 +/- 2.7 microg/ml, n = 17; mean +/- SEM) in uremic patients aged 40-55 years receiving hemodialysis treatment than in healthy younger subjects (3.61 +/- 0.19 microg/ml, n = 22), aged 18-23 years. However, the hair concentration of CMPF tended to be lower in the patients (6.8 +/- 1.7 ng/10 mg hair) than in the healthy younger subjects (15.8 +/- 4.5 ng/10 mg) and was significantly lower than that in the healthy age-matched subjects (22.4 +/- 5.3 ng/10 mg, n = 12), aged 40-47 years. Since CMPF was measurable in the sweat (4.4 +/- 3.7 ng/mg) collected from six out of seven healthy subjects examined, it was suggested that the contribution of sweat to the measurement of CMPF in hair was considerable. The fact that the uremic patients undergoing hemodialysis therapy had less sweat than healthy subjects may explain the lower concentration of CMPF in the patients' hair. The pathophysiological roles of CMPF in the body were attempted to be explored by using excised guinea pig organs, and human platelets and neutrophils. CMPF showed no remarkable effects in the concentration range of < or =10(-4) M except for only slight suppression of spontaneous contracture of guinea pig tenia coli at 10(-4) M. As far as the organs and tissues examined in the present study are concerned, the biological activity of CMPF itself, if any, may be very weak. Precaution should be taken against the delivery of a substance through sweat to hair when a small amount of substance is attempted to be measured in hair by employing a sensitive analytical method.

Ruptured retroperitoneal mucinous cystadenocarcinoma with synchronous gastric carcinoma and a long postoperative survival: case report

We describe an 86-year-old woman with a long survival following surgey for a massive retroperitoneal mucinous cystadenocarcinoma and a synchronous gastric carcinoma. Computed tomography showed a huge tumor with septation and calcification. Upper gastrointestinal radiography showed the additional gastric lesion. At operation, the 23 x 20 x 12-cm retroperitoneal tumor had ruptured. Tumor resection and distal gastrectomy including regional lymph nodes were performed. Mucinous peritoneal implants were removed as completely as possible. Histologically, the mucinous tumor showed limited invasion, whereas the poorly differentiated gastric adenocarcinoma showed no serosal invasion. Among 18 retroperitoneal mucinous cystadenocarcinomas reported in the English literature since 1965, only ours was associated with gastric carcinoma. Despite peritoneal implants, our patient has survived for 6 years without clinical recurrence. As at other sites, retroperitoneal mucinous cystadenocarcinoma often grows slowly. Total removal, even after peritoneal dissemination, can result in long survival.

Involvement of p42/p44 mitogen-activated protein kinase in prostaglandin f(2alpha)-stimulated induction of heat shock protein 27 in osteoblasts

We previously reported that prostaglandin F(2alpha) (PGF(2alpha)) activates both phosphoinositide-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D in osteoblast-like MC3T3-E1 cells and then induces the activation of protein kinase C (PKC). In this study, we investigated the effect of PGF(2alpha) on the induction of heat shock protein 27 (HSP27), a low-molecular-weight heat shock protein, in these cells. PGF(2alpha) significantly induced the accumulation of HSP27 dose-dependently within the range of 10 nM to 10 microM. PGF(2alpha) stimulated the increase in the levels of mRNA for HSP27. A total of 10 nM 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of PKC, induced the accumulation of HSP27. The stimulative effect of PGF(2alpha) was reduced in the PKC down-regulated cells. Calphostin C, a specific inhibitor of PKC, suppressed the PGF(2alpha)-induced HSP27 accumulation as well as that induced by TPA. HSP27 induction by PGF(2alpha) was reduced by U-73122, a phospholipase C inhibitor, or propranolol, a phosphatidic acid phosphohydrolase inhibitor. PGF(2alpha) and TPA stimulated p42/p44 mitogen-activated protein (MAP) kinase. PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase, suppressed the induction of HSP27 stimulated by PGF(2alpha) or TPA. PD98059 and calphostin C reduced the levels of mRNA for HSP27 increased by PGF(2alpha). These results indicate that PGF(2alpha) stimulates the induction of HSP27 via p42/p44 MAP kinase activation, which depends on upstream PKC activation in osteoblasts.

Clinical utility of simultaneous measurement of serum high-sensitivity des-gamma-carboxy prothrombin and Lens culinaris agglutinin A-reactive alpha-fetoprotein in patients with small hepatocellular carcinoma

OBJECTIVE

To evaluate the diagnostic efficacy of simultaneous measurements of high-sensitivity des-gamma-carboxy prothrombin (H-DCP) and Lens culinaris agglutinin A-reactive alpha-fetoprotein (AFP-L3) in small hepatocellular carcinoma (HCC).

METHODS

Sixty-one patients with small HCCs < or = 2 cm in diameter and 134 controls (chronic hepatitis: 59 cases; cirrhosis: 75 cases) were examined. H-DCP was measured by electrochemiluminescence immunoassay (cut-off 40 mAU/ml (milli-arbitrary units/ml) and AFP-L3% (percentage of AFP-L3/total AFP) by lectin-affinity electrophoresis coupled with the antibody-affinity blotting method (cut-off 10%). Fifty-six patients were histologically diagnosed and the remaining five patients were diagnosed clinically.

RESULTS

Of 61 patients, 27 (44.3%) were positive for H-DCP and 14 (23.0%) were positive for AFP-L3. There was no correlation between H-DCP and AFP-L3%. Nineteen patients (31.1%) had positive H-DCP alone. Six patients (9.8%) had positive AFP-L3 alone, and in eight patients (13.1%) both markers were positive. In combination assay, 33 of 61 patients (54.1%) were positive for either marker; specificity and accuracy were 97.8% and 84.1%, respectively. There was a tendency for the AFP-L3% to be elevated in patients with moderately or poorly differentiated HCC (P= 0.0564) and multiple HCC nodules (P= 0.0316), while the H-DCP showed no elevation related to the tumour type.

CONCLUSION

The detection rate of small HCC was improved by combination assay with H-DCP and AFP-L3%. Our results indicate that the markers are complementary and useful for the diagnosis and evaluation of small HCC when measured simultaneously.

Endothelin-1 stimulates heat shock protein 27 induction in osteoblasts: involvement of p38 MAP kinase

We previously reported that endothelin-1 (ET-1) activates p42/p44 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells and consequently induces synthesis of interleukin-6. In the present study, we investigated the effect of ET-1 on the induction of heat shock protein 27 (HSP 27) in MC3T3-E1 cells. ET-1 time and dose dependently stimulated HSP 27 accumulation. ET-1 induced an increase in the levels of mRNA for HSP 27. Both staurosporine and calphostin C, inhibitors of protein kinase C (PKC), suppressed the ET-1-induced HSP 27 accumulation. 12-O-tetradecanoylphorbol 13-acetate (TPA), a PKC activator, induced the HSP 27 accumulation and the expression of mRNA for HSP 27. The ET-1-stimulated HSP 27 accumulation was reduced in PKC-downregulated MC3T3-E1 cells. The HSP 27 accumulation by ET-1 was not suppressed by PD-98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. ET-1 or TPA induced the phosphorylation of p38 MAP kinase. SB-203580, an inhibitor of p38 MAP kinase, reduced the ET-1-stimulated HSP 27 accumulation. Calphostin C and U-73122, a phospholipase C inhibitor, suppressed the ET-1-induced phosphorylation of p38 MAP kinase. U-73122 and propranolol, a phosphatidic acid phosphohydrolase inhibitor, reduced the ET-1-stimulated HSP 27 accumulation. SB-203580 suppressed the ET-1-stimulated increase in the mRNA levels for HSP 27. These results strongly suggest that ET-1 stimulates HSP 27 induction in osteoblasts and that p38 MAP kinase activation is involved in the HSP 27 induction.

Mitogen-activated protein (MAP) kinases are involved in interleukin-1 (IL-1)-induced IL-6 synthesis in osteoblasts: modulation not of p38 MAP kinase, but of p42/p44 MAP kinase by IL-1-activated protein kinase C

We previously reported that interleukin-1alpha (IL-1alpha)-induced activation of protein kinase C (PKC) via phosphatidylcholine-specific phospholipase C (PC-PLC) limits IL-6 synthesis induced by IL-1alpha itself in osteoblast-like MC3T3-E1 cells. In the present study, we further investigated the mechanism behind IL-1alpha-induced IL-6 synthesis in MC3T3-E1 cells. IL-1alpha time-dependently stimulated the phosphorylation of both p42/p44 mitogen-activated protein (MAP) kinase and p38 MAP kinase. PD98059, a specific inhibitor of the upstream kinase that activates p42/p44 MAP kinase, inhibited the IL-1alpha-induced IL-6 synthesis as well as the phosphorylation of p42/p44 MAP kinase induced by IL-1alpha. SB203580, a specific inhibitor of p38 MAP kinase, also reduced both the phosphorylation of p38 MAP kinase and the IL-6 synthesis. 1-Oleoyl-2-acetylglycerol, an activator of PKC, suppressed the IL-1alpha-induced IL-6 synthesis. Calphostin C, a specific inhibitor of PKC, or D-609, a specific inhibitor of PC-PLC, significantly enhanced the IL-1alpha-induced phosphorylation of p42/p44 MAP kinase without affecting the phosphorylation of p38 MAP kinase. The phosphorylation of p42/p44 MAP kinase by IL-1alpha was markedly increased in PKC-down-regulated MC3T3-E1 cells. Neither 12-O-tetradecanoylphorbol-13-acetate, known to be an activator of PKC, nor 1-oleoyl-2-acetylglycerol affected the phosphorylation of p38 MAP kinase induced by IL-1alpha. These results strongly suggest that IL-1alpha-induced IL-6 synthesis is mediated via activations of both p42/p44 MAP kinase and p38 MAP kinase in osteoblasts, and that PKC activated by IL-1alpha itself negatively regulates IL-6 synthesis at a point upstream from p42/p44 MAP kinase.

Sphingosine 1-phosphate induces heat shock protein 27 via p38 mitogen-activated protein kinase activation in osteoblasts

We previously showed that sphingosine 1-phosphate acts as a second messenger for tumor necrosis factor alpha-induced interleukin-6 synthesis in osteoblast-like MC3T3-E1 cells and that the synthesis by sphingosine 1-phosphate is dependent on p42/p44 mitogen-activated protein (MAP) kinase activation. In the present study, we investigated the effect of sphingosine 1-phosphate on the induction of heat shock protein 27 (HSP27) in MC3T3-E1 cells. Not C2-ceramide, but sphingosine and sphingosine 1-phosphate significantly induced HSP27 accumulation dose dependently in the range between 1microM and 30 microM. DL-threo-dihydrosphingosine, an inhibitor of sphingosine kinase, markedly inhibited the sphingosine-induced HSP27 accumulation. Sphingosine 1-phosphate induced increase in the levels of the mRNA for HSP27. Sphingosine 1-phosphate stimulated the phosphorylation of p38 MAP kinase. The sphingosine 1-phosphate-induced HSP27 accumulation was dose dependently suppressed by SB203580, an inhibitor of p38 MAP kinase, but not PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. SB203580 reduced the sphingosine 1-phosphate-induced increase of mRNA for HSP27. These results strongly suggest that sphingosine 1-phosphate-stimulated HSP27 induction is mediated via p38 MAP kinase activation in osteoblasts.

Failure of preventive effects of 2-deoxy-D-glucose on ischemia-induced gerbil hippocampal neuronal damage by induced hyperthermia

Post-ischemic administration of 2-deoxy-D-glucose (2-DG), a glucose antimetabolite, markedly reduces the occurrence of ischemia-induced delayed neuronal death (DND) in the gerbil hippocampus. This means that the reduction of energy dependent metabolism after ischemia prevents ischemia-induced damages of hippocampal neurons. In the present study, we demonstrated hyperthermia during ischemia fails to preserve neurons in hippocampal CA1 of 2-DG treated gerbil following transient forebrain ischemia.

Prostaglandin D2 induces interleukin-6 synthesis via Ca2+ mobilization in osteoblasts: regulation by protein kinase C

We previously showed that prostaglandin (PG) D2 stimulates Ca2+ influx from extracellular space and activates phosphoinositidic (PI)-hydrolyzing phospholipase C and phosphatidylcholine (PC)-hydrolyzing phospholipase D independently from PGE2 or PGF2alpha in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of PGD2 on the synthesis of interleukin-6 (IL-6) and its regulatory mechanism in MC3T3-E1 cells. PGD2 significantly stimulated IL-6 synthesis dose-dependently in the range between 10 nM and 10 microM. The depletion of extracellular Ca2+ by EGTA reduced the PGD2-induced IL-6 synthesis. TMB-8, an inhibitor of intracellular Ca2+ mobilization, significantly inhibited the PGD2-induced IL-6 synthesis. On the other hand, calphostin C, a specific inhibitor of protein kinase C (PKC), enhanced the synthesis of IL-6 induced by PGD2. In addition, U-73122, an inhibitor of phospholipase C, and propranolol, a phosphatidic acid phosphohydrolase inhibitor, enhanced the PGD2-induced IL-6 synthesis. These results strongly suggest that PGD2 stimulates IL-6 synthesis through intracellular Ca2+ mobilization in osteoblasts, and that the PKC activation by PGD2 itself regulates the over-synthesis of IL-6.

Involvement of p38 mitogen-activated protein kinase in basic fibroblast growth factor-induced interleukin-6 synthesis in osteoblasts

We previously showed that basic fibroblast growth factor (bFGF)-induced activation of protein kinase C (PKC) via phosphatidylinositol-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D suppresses interleukin-6 (IL-6) synthesis by bFGF itself in osteoblast-like MC3T3-E1 cells. In the present study, we further investigated the mechanism underlying the bFGF-induced IL-6 synthesis in MC3T3-E1 cells. bFGF time-dependently induced the phosphorylation of p38 mitogen-activated protein (MAP) kinase. SB203580, a specific inhibitor of p38 MAP kinase, suppressed the bFGF-induced IL-6 synthesis dose-dependently. The phosphorylation of p38 MAP kinase by bFGF was suppressed by TMB-8, an inhibitor of intracellular Ca(2+) mobilization, or the depletion of extracellular Ca(2+) with EGTA. A23187, a Ca-ionophore, stimulated the phosphorylation of p38 MAP kinase. SB203580 inhibited the A23187-induced synthesis of IL-6. 1-Oleoyl-2-acetyl-sn-glycerol, a synthetic diacylglycerol activating PKC, reduced the bFGF-induced IL-6 synthesis. 12-O-Tetradecanoylphorbol-13-acetate, an activator of PKC, attenuated the phosphorylation of p38 MAP kinase by bFGF, but did not affect the A23187-induced phosphorylation. These results strongly suggest that bFGF-induced IL-6 synthesis is mediated via p38 MAP kinase activation in osteoblasts, and that PKC acts at a point upstream from p38 MAP kinase.

Sphingosine 1-phosphate regulates heat shock protein 27 induction by a p38 MAP kinase-dependent mechanism in aortic smooth muscle cells

In an aortic smooth muscle cell line, A10 cells, we investigated the effect of sphingosine 1-phosphate on the induction of heat shock protein 27 (HSP27), a low-molecular-weight heat shock protein. Sphingosine 1-phosphate significantly induced the accumulation of HSP27 in a pertussis toxin-sensitive manner. The effect was dose-dependent in the range between 0.1 and 30 microM. Sphingosine 1-phosphate stimulated an increase in the levels of mRNA for HSP27. Sphingosine 1-phosphate stimulated both p42/p44 mitogen-activated protein (MAP) kinase and p38 MAP kinase activation. PD98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase, did not affect sphingosine 1-phosphate-stimulated HSP27 induction. In contrast, SB203580, an inhibitor of p38 MAP kinase, reduced sphingosine 1-phosphate-induced HSP27 induction. SB203580 reduced the levels of mRNA for HSP27 induced by sphingosine 1-phosphate. These results indicate that sphingosine 1-phosphate stimulates the induction of HSP27 via p38 MAP kinase activation in aortic smooth muscle cells.

Comparative antiplatelet effects of aspirin, vapiprost and GR144053, a GPIIb/IIIa antagonist, with a special reference to the role of platelet microaggregates

Microthrombi produced have a potential to form larger thrombi, leading to vascular occlusions. Recently, a new device to easily detect microaggregates using laser-light scattering (LS) has been developed. We adopted this device to comparatively evaluate the inhibitory effects of aspirin (1,3 or 10 mg kg(-1)), vapiprost (0.3, 1 or 3 mg kg(-1)) or GR144053 (0.1, 0.3 or 1 mg kg(-1)) on ex vivo aggregation of hamster platelets in relation to their in vivo antithrombotic effects. A transluminal thrombus was produced in the hamster femoral artery by the photochemical reaction. Each compound was injected i.v. as a bolus 10 min prior to the reaction, showing a dose-dependent antithrombotic effect, i.e. they prolonged the time before the artery occluded. At that time cyclic flow reductions occurred more marked when aspirin or vapiprost was given. At the end of experiments, blood was collected to evaluate the platelet aggregation using both the new LS device and the conventional optical density (OD) method. Many more small aggregates were still formed when the highest dose of aspirin or vapiprost was used as compared with that of GR144053, although suppression of the platelet aggregation using the OD method, prolongation of the occlusion time and the bleeding time were quite similar. In conclusion, a GPIIb/IIIa antagonist markedly suppressed the microthrombi and reduced the cyclic flow reduction. This further indicates the importance of small aggregates as triggers of thrombosis and shows that prevention of their formation may result in improved vascular patency after thrombotic insult.

Comparison of the antithrombotic effects and bleeding risk of fractionated aurin tricarboxylic acid and the GPIIb/IIIa antagonist GR144053 in a hamster model of stenosis

The present study compared the antithrombotic properties of fractionated aurin tricarboxylic acid (ATA), an inhibitor of platelet glycoprotein (GP) Ib, and GR144053, a GPIIb/IIIa antagonist, in a hamster model of stenosis. Endothelial cell injury in the hamster carotid artery was achieved by a 2F modified catheter. Arterial blood flow in the control groups was interrupted 5.4+/-0.9 minutes after the injury. When ATA (0.01, 0.03, 0.1, 0.3, and 1.0 mg/kg per hour) or GR144053 (0.1, 0.3, and 1.0 mg/kg per hour) were continuously infused intravenously, the time elapse before the vessel completely occluded was prolonged in a dose-dependent manner. However, all arteries in the ATA-treated groups ultimately occluded during the observation period even if the aggregation of platelets ex vivo and induced by botrocetin was completely inhibited. When either ATA (0.1 mg/kg per hour) or GR144053 (0.3 mg/kg per hour) were infused via an implanted osmotic pump together with tissue-type plasminogen activator (tPA), late patency of the reperfused artery was improved compared to that of arteries treated with TPA alone. However, the cyclic reflow pattern after reperfusion on days 0 and 1 was not reduced by the ATA treatment. The bleeding time was significantly prolonged when either ATA or GT144053 was coadministered with tPA. The treatment with ATA showed an especially marked prolongation of the bleeding time. In conclusion, both inhibition of platelet activation by ATA or GR144053 prevent arterial thrombosis and enhance the thrombolytic effect of tPA, but GR144053 was more protective in its antithrombotic effect and more effective during thrombolytic therapy than ATA.

Neuronal apoptosis studied by a sequential TUNEL technique: a method for tract-tracing

A novel tract-tracing procedure by using a sequential in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling of DNA fragments (TUNEL) is described. This method identifies fragmented DNA transported into neuronal fibers in tissue sections of gerbil hippocampal CA1 neurons following transient forebrain ischemia. The transported DNA has been confirmed by another method, fluorescence DNA detection technique by DAPI. Many methods have been developed to study the neuroanatomical connections in the central nervous system. Principally, these techniques are based on tract-tracing studies using xenobiotics into the central nervous system. Our tract-tracing method is originated from an intrinsic marker that is produced during the apoptotic process of neurons. Furthermore, the advantage of this method is that only the selected cells undergoing apoptosis are recognized and traced to the end of the related neuronal fiber. Usually, apoptotic cells possess intact intracellular metabolic mechanisms until completion of cell death. Thus, apoptotic neurons retain the axonal transport mechanisms which enables us to detect fragmented DNA moving from nuclei to distal terminals of neuronal fibers. Since TUNEL-positive DNA movement within neuronal fibers occurs only during a limited period, it is essential that a time-course of the TUNEL technique is used to study tract-tracing of apoptotic neurons. Although this method can identify only the apical dendrites of cells that are undergoing apoptosis during the limited period, some projections of the gerbil hippocampal CA1 neurons undergoing apoptosis are clearly demonstrated.

Effect of ceramide on interleukin-6 synthesis in osteoblast-like cells

We previously showed that prostaglandin (PG) E1 stimulates the synthesis of interleukin-6 (IL-6) through activation of protein kinase (PK) A in osteoblast-like MC3T3-E1 cells and that PGF2alpha induces IL-6 synthesis through PKC activation. In other studies, we demonstrated that thrombin stimulates IL-6 synthesis, which depends on intracellular Ca2+ mobilisation in these cells and that tumour necrosis factor-alpha (TNF) induces IL-6 synthesis through sphingosine 1-phosphate, a product of sphingomyelin turnover. In the present study, among sphingomyelin metabolites, we examined the effect of ceramide on the IL-6 synthesis induced by various agonists in MC3T3-E1 cells. C2-ceramide, a cell-permeable ceramide analogue, suppressed the PGE1-induced IL-6 synthesis. C2-ceramide inhibited the IL-6 synthesis induced by PGF2alpha or 12-O-tetradecanoylphorbol-13-acetate, an activator of PKC. C2-ceramide reduced the IL-6 synthesis induced by cholera toxin, forskolin or dibutyryl cAMP. C2-ceramide inhibited the IL-6 synthesis induced by thrombin. The IL-6 synthesis stimulated by thapsigargin, which is known to stimulate Ca2+ mobilisation from intracellular Ca2+ stores, or A23187, a Ca-ionophore, was also inhibited by C2-ceramide. C2-ceramide did not affect the IL-6 synthesis induced by interleukin-1. On the contrary, C2-ceramide enhanced the TNF-induced IL-6 synthesis. D,L-threo-dihydrosphingosine, an inhibitor of sphingosine kinase, inhibited the enhancement by C2-ceramide as well as the TNF-effect. These results strongly suggest that ceramide modulates the IL-6 synthesis stimulated by various agonists in osteoblasts.

Prevention of ischemia-induced hippocampal neuronal damage by 2-deoxy-D-glucose in gerbils

It has been reported that delayed neuronal death (DND) in the hippocampus following transient forebrain ischemia is associated with internucleosomal DNA fragmentation, indicating apoptosis. This suggests that the process of DND is energy dependent. Transient severe forebrain ischemia was induced in Mongolian gerbils by bilateral occlusion of the common carotid arteries. Post-ischemic administration of 2-deoxy-D-glucose (2-DG), a glucose antimetabolite, markedly reduced the occurrence of ischemia-induced DNA fragmentation and DND in the hippocampus. These results suggest that the reduction of energy dependent metabolism after ischemia may be an attractive therapeutic strategy for preserving hippocampal neurons vulnerable to ischemia.

Application of high energy shock waves to cancer treatment in combination with cisplatin and ATX-70

BACKGROUND

The anti-tumor effects of high-energy shock waves (HESW) in combination with cisplatin (CDDP) and ATX-70, as a photosensitizer, were investigated in vitro and in vivo.

METHODS

Active oxygen generation by HESW was studied by means of electron spin resonance (ESR) system. The anti-tumor effects of HESW in combination with cisplatin (CDDP) and ATX-70 was investigated in vitro and in vivo.

RESULTS

HESW exposure induced singlet oxygen or hydroxyl radical. Adding ATX-70 enhanced the cell damage induced by HESW dose-dependently. Ascorbic acid inhibited the combined effect of HESW and ATX-70. Adding CDDP did not enhanced cell damage by HESW. The combined therapy of HESW, CDDP and ATX-70 showed further inhibition of tumor growth in vivo.

CONCLUSIONS

These results indicate that HESW activated ATX-70, and that the anti-tumor effect of HESW and ATX-70 was caused by active oxygen generation. HESW is able to be utilized with any other cancer treatment.

p42/p44 mitogen-activated protein kinase activation is involved in prostaglandin F2alpha-induced interleukin-6 synthesis in osteoblasts

Prostaglandin F2alpha (PGF2alpha) significantly induced p42/p44 mitogen-activated protein (MAP) kinase activity in osteoblast-like MC3T3-E1 cells. PD98059, a selective inhibitor of MAP kinase kinase, inhibited PGF2alpha-induced interleukin-6 (IL-6) synthesis as well as PGF2alpha-induced p42/p44 MAP kinase activation. PD98059 suppressed the IL-6 synthesis induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC) activator, or NaF, an activator of heterotrimeric GTP-binding protein, as well as the p42/p44 MAP kinase activation by TPA or NaF. Calphostin C, a highly potent and specific inhibitor of PKC, inhibited the PGF2alpha-induced p42/p44 MAP kinase activity. These results strongly suggest that PKC-dependent p42/p44 MAP kinase activatioin is involved in PGF2alpha-induced IL-6 synthesis in osteoblasts.