Edaravone attenuates sustained pial arteriolar vasoconstriction independently of endothelial function after unclamping of the abdominal aorta in rabbits.

BACKGROUND: Cerebral blood flow (CBF) has direct effects on neuronal function and neurocognitive disorders. Oxidative stress from abdominal aortic surgery is important in the pathophysiology of CBF impairment. We investigated the effect of edaravone on the pial arteriolar diameter changes induced by abdominal aortic surgery and the involvement of the endothelium in the changes. METHODS: The closed cranial window technique was used in rabbits to measure changes in pial arteriolar diameter after the unclamping of abdominal aortic cross-clamping with an intravenous free radical scavenger, edaravone (control group [n = 6], edaravone 10 µg/kg/min [n = 6], 100 µg/kg/min [n = 6]). Pial vasodilatory responses to topical application of acetylcholine (ACh) into the cranial window were investigated before abdominal aortic cross-clamping and after unclamping with intravenous administration of edaravone (control group [n = 6], edaravone 100 µg/kg/min [n = 6]). RESULTS: Aortic unclamping-induced vasoconstriction was significantly attenuated by continuous infusion of edaravone at 100 µg/kg/min. Topical ACh after unclamping did not produce any changes in pial arteriolar responses in comparison to before aortic cross-clamping in the control or edaravone groups. The changes in the response to topical ACh after unclamping in the saline and edaravone groups did not differ significantly. CONCLUSIONS: Free radicals during abdominal aortic surgery might have contracted cerebral blood vessels independently of endothelial function in rabbits. Suppression of free radicals attenuated the sustained pial arteriolar vasoconstriction after aortic unclamping. Thus, the free radical scavenger might have some brain protective effect that maintains CBF independently of endothelial function.

Sphingosine 1-phosphate (S1P) suppresses the collagen-induced activation of human platelets via S1P4 receptor.

Sphingosine 1-phosphate (S1P) is as an extracellular factor that acts as a potent lipid mediator by binding to specific receptors, S1P receptors (S1PRs). However, the precise role of S1P in human platelets that express S1PRs has not yet been fully clarified. We previously reported that heat shock protein 27 (HSP27) is released from human platelets accompanied by its phosphorylation stimulated by collagen. In the present study, we investigated the effect of S1P on the collagen-induced platelet activation. S1P pretreatment markedly attenuated the collagen-induced aggregation. Co-stimulation with S1P and collagen suppressed collagen-induced platelet activation, but the effect was weaker than that of S1P-pretreatment. The collagen-stimulated secretion of platelet-derived growth factor (PDGF)-AB and the soluble CD40 ligand (sCD40L) release were significantly reduced by S1P. In addition, S1P suppressed the collagen-induced release of HSP27 as well as the phosphorylation of HSP27. S1P significantly suppressed the collagen-induced phosphorylation of p38 mitogen-activated protein kinase. S1P increased the levels of GTP-bound Gαi and GTP-bound Gα13 coupled to S1PPR1 and/or S1PR4. CYM50260, a selective S1PR4 agonist, but not SEW2871, a selective S1PR1 agonist, suppressed the collagen-stimulated platelet aggregation, PDGF-AB secretion and sCD40L release. In addition, CYM50260 reduced the release of phosphorylated-HSP27 by collagen as well as the phosphorylation of HSP27. The selective S1PR4 antagonist CYM50358, which failed to affect collagen-induced HSP27 phosphorylation, reversed the S1P-induced attenuation of HSP27 phosphorylation by collagen. These results strongly suggest that S1P inhibits the collagen-induced human platelet activation through S1PR4 but not S1PR1.

Hepatozoon apri n. sp. (Adeleorina: Hepatozoidae) from the Japanese wild boar Sus scrofa leucomystax (Mammalia: Cetartiodactyla).

Hepatozoon apri n. sp. is described from Japanese wild boars Sus scrofa leucomystax in Japan. The gamonts in the peripheral blood leukocytes were 11.6 ± 1.4 × 6.7 ± 1.3 µm in size. The meronts in the muscle tissues were 35.0-47.5 µm in length and 26.5-30 µm in width. A high rate (53.0%) of infection was found by nested PCR using muscle specimens from 181 wild boars captured in Tokushima, Japan. A phylogenetic analysis based on 18S rRNA gene sequences revealed that H. apri n. sp. detected in wild boars is closely related to Hepatozoon spp. isolated from carnivores. This is the first description of a species belonging to the genus Hepatozoon detected in ungulates.

AICAR reduces the collagen-stimulated secretion of PDGF-AB and release of soluble CD40 ligand from human platelets: Suppression of HSP27 phosphorylation via p44/p42 MAP kinase.

We have previously reported that collagen-induced phosphorylation of heat shock protein (HSP) 27 via p44/p42 mitogen-activated protein (MAP) kinase in human platelets is sufficient to induce the secretion of platelet-derived growth factor (PDGF)-AB and the release of soluble cluster of differentiation 40 ligand (sCD40L). Adenosine monophosphate-activated protein kinase (AMPK), which is known to regulate energy homeostasis, has a crucial role as an energy sensor in various eukaryotic cells. The present study investigated the effects of 5-aminoimidazole-4-carboxamide-1-ß-d-ribofuranosyl 5'-monophosphate (AICAR), which is an activator of AMPK, on the collagen-induced activation of human platelets. It was demonstrated that AICAR dose-dependently reduced collagen-stimulated platelet aggregation up to 1.0 µM. Analysis of the size of platelet aggregates demonstrated that AICAR decreased the ratio of large aggregates (50-70 µm), whereas the ratio of small aggregates (9-25 µm) was increased by AICAR administration. AICAR markedly attenuated the phosphorylation levels of p44/p42 MAP kinase and HSP27, which are induced by collagen. Furthermore, AICAR significantly decreased the secretion of PDGF-AB and the collagen-induced release of sCD40L. These results indicated that AICAR-activated AMPK may reduce the secretion of PDGF-AB and the collagen-induced release of sCD40L by inhibiting HSP27 phosphorylation via p44/p42 MAP kinase in human platelets.

Thrombin Receptor-Activating Protein (TRAP)-Activated Akt Is Involved in the Release of Phosphorylated-HSP27 (HSPB1) from Platelets in DM Patients.

It is generally known that heat shock protein 27 (HSP27) is phosphorylated through p38 mitogen-activated protein (MAP) kinase. We have previously reported that HSP27 is released from human platelets associated with collagen-induced phosphorylation. In the present study, we conducted an investigation into the effect of thrombin receptor-activating protein (TRAP) on the release of HSP27 in platelets in type 2 diabetes mellitus (DM) patients. The phosphorylated-HSP27 levels induced by TRAP were directly proportional to the aggregation of platelets. The levels of phosphorylated-HSP27 (Ser-78) were correlated with the levels of phosphorylated-p38 MAP kinase and phosphorylated-Akt in the platelets stimulated by 10 µM TRAP but not with those of phosphorylated-p44/p42 MAP kinase. The levels of HSP27 released from the TRAP (10 µM)-stimulated platelets were correlated with the levels of phosphorylated-HSP27 in the platelets. The released platelet-derived growth factor-AB (PDGF-AB) levels were in parallel with the HSP27 levels released from the platelets stimulated by 10 µM TRAP. Although the area under the curve (AUC) of small aggregates (9-25 µm) induced by 10 µM TRAP showed no significant correlation with the released HSP27 levels, AUC of medium aggregates (25-50 µm), large aggregates (50-70 µm) and light transmittance were significantly correlated with the released HSP27 levels. TRAP-induced phosphorylation of HSP27 was truly suppressed by deguelin, an inhibitor of Akt, in the platelets from a healthy subject. These results strongly suggest that TRAP-induced activation of Akt in addition to p38 MAP kinase positively regulates the release of phosphorylated-HSP27 from human platelets, which is closely related to the platelet hyper-aggregation in type 2 DM patients.

Release of Phosphorylated HSP27 (HSPB1) from Platelets Is Accompanied with the Acceleration of Aggregation in Diabetic Patients.

We investigated the relationship between HSP27 phosphorylation and collagen-stimulated activation of platelets in patients with diabetes mellitus (DM). Platelet-rich plasma was prepared from blood of type 2 DM patients. The platelet aggregation was analyzed in size of aggregates by an aggregometer using a laser scattering method. The protein phosphorylation was analyzed by Western blotting. Phosphorylated-HSP27 and PDGF-AB released from platelets were measured by ELISA. The phosphorylated-HSP27 levels at Ser-78 and Ser-82 induced by collagen were directly proportional to the platelet aggregation. Total HSP27 levels in platelets were decreased concomitantly with the phosphorylation. The released HSP27 levels were significantly correlated with the phosphorylated levels of HSP27 in the platelets stimulated by 0.3 µg/ml collagen. The low dose collagen-stimulated release of HSP27 was detected but relatively small in healthy donors. The released levels of PDGF-AB were in parallel with the levels of released HSP27. Area under the curve (AUC) of small aggregation (9-25 µm) induced by 0.3 µg/ml collagen was inversely proportional to the levels of released HSP27. AUC of large aggregation (50-70 µm) was directly proportional to the levels of released HSP27. Exogenous recombinant phosphorylated- HSP27 hardly affected the aggregation or the released levels of PDGF-AB induced by collagen. These results strongly suggest that HSP27 is released from human platelets accompanied with its phosphorylation induced by collagen, which is correlated with the acceleration of platelet aggregation in type 2 DM patients.

Involvement of Rac in thromboxane A2­induced human platelet activation: regulation of sCD40 ligand release and PDGF­AB secretion.

We have previously shown that glycoprotein Ib/IX/V activation stimulates the release of the soluble CD40 ligand (sCD40L) via the generation of thromboxane A2 from human platelets. In the present study, the role of Rac, which is a member of the Rho family, was investigated in the thromboxane A2­stimulated release of platelet­derived growth factor (PDGF)­AB and sCD40L in human platelets. U46619, a thromboxane receptor agonist, stimulated the activation of Rac time­dependently in human platelets, and NSC23766, a selective inhibitor of the Rac­guanine nucleotide exchange factor interaction, reduced the U46619­induced platelet aggregation. NSC23766 markedly suppressed the U46619­induced p38 mitogen-activated protein (MAP) kinase phosphorylation. The thromboxane A2­induced release of PDGF­AB and sCD40L was significantly suppressed by NSC23766 in a dose­dependent manner. In addition, NSC23766 reduced the sCD40L release stimulated by ristocetin, a glycoprotein Ib/IX/V activator. These results indicate that Rac regulates the thromboxane A2­induced stimulation of PDGF­AB secretion and sCD40L release via the p38 MAP kinase in human platelets.

Rac regulates collagen-induced HSP27 phosphorylation via p44/p42 MAP kinase in human platelets.

We previously reported that the collagen-induced phosphorylation of heat shock protein (HSP) 27 via p44/p42 mitogen-activated protein (MAP) kinase is sufficient to induce the secretion of platelet-derived growth factor (PDGF)-AB and the release of soluble CD40 ligand (sCD40L) from human platelets. It has been shown that Rac, which belongs to the Rho family of small GTPases, is involved in the collagen-induced platelet aggregation. In this study, we investigated the role of Rac in the collagen-stimulated release of PDGF-AB and sCD40L in human platelets. Human blood was donated from healthy volunteers and platelet-rich plasma was obtained from the blood samples. The samples were then treated with 1.0 µg/ml collagen for 0, 1, 3, or 5 min and Rac1 activity was determined using the Rac1 Activation Assay kit. We found that collagen stimulated the activation of Rac in human platelets in a time-dependent manner. However, pre-treatment with NSC23766, a selective inhibitor of Rac-guanine nucleotide exchange factor interaction, reduced the collagen-induced platelet aggregation. NSC23766 markedly attenuated not only the collagen-induced p44/p42 MAP kinase phosphorylation, but also the phosphorylation of HSP27 at three serine residues (Ser-15, Ser-78 and Ser-82). In addition, the collagen­induced release of PDGF-AB and sCD40L was significantly suppressed by NSC23766 in a dose-dependent manner. These results strongly suggest that Rac regulates the collagen-induced HSP27 phosphorylation via p44/p42 MAP kinase in human platelets, resulting in the stimulation of PDGF-AB secretion and the release of sCD40L.

Thrombopoietin amplifies ADP-induced HSP27 phosphorylation in human platelets: importance of pre-treatment.

It has been shown that thrombopoietin (TPO) amplifies agonist-induced platelet activation. However, the precise mechanism of action of TPO has not yet been fully elucidated. We have previously reported that the adenosine diphosphate (ADP)­induced phosphorylation of heat shock protein 27 (HSP27) via the p38 mitogen-activated protein (MAP) kinase pathway correlates with the ADP-induced platelet-derived growth factor (PDGF)-AB secretion and the release of soluble CD40 ligand (sCD40L) from human platelets. In the present study, we investigated the effects of TPO on platelet activation induced by ADP. We examined the effects of TPO on ADP-induced platelet activation under different treatments: TPO was administered 15 min prior to stimulation with ADP (pre-treatment); TPO and ADP were simultaneously administered (simultaneous treatment); and TPO was administered 2 min following stimulation with ADP (post-treatment). TPO, which alone had no effect on platelet aggregation, synergistically enhanced the ADP (1 mM)-induced platelet aggregation only when it was administered prior to stimulation with ADP. Pre-treatment with TPO significantly increased the secretion of PDGF-AB and the release of sCD40L, and markedly enhanced the ADP-induced phosphorylation of p38 MAP kinase and HSP27 in the platelets. However, simultaneous treatment with TPO or TPO post-treatment failed to affect the ADP-induced platelet aggregation, the secretion of PDGF-AB, the release of sCD40L and the phosphorylation p38 MAP kinase or HSP27. These results strongly suggest that pre-treatment with TPO significantly amplifies ADP-induced HSP27 phosphorylation via the p38 MAP kinase pathway in human platelets.

Dynamic properties influence the perception of facial expressions.

Two experiments were conducted to investigate the role played by dynamic information in identifying facial expressions of emotion. Dynamic expression sequences were created by generating and displaying morph sequences which changed the face from neutral to a peak expression in different numbers of intervening intermediate stages, to create fast (6 frames), medium (26 frames), and slow (101 frames) sequences. In experiment 1, participants were asked to describe what the person shown in each sequence was feeling. Sadness was more accurately identified when slow sequences were shown. Happiness, and to some extent surprise, was better from faster sequences, while anger was most accurately detected from the sequences of medium pace. In experiment 2 we used an intensity-rating task and static images as well as dynamic ones to examine whether effects were due to total time of the displays or to the speed of sequence. Accuracies of expression judgments were derived from the rated intensities and the results were similar to those of experiment 1 for angry and sad expressions (surprised and happy were close to ceiling). Moreover, the effect of display time was found only for dynamic expressions and not for static ones, suggesting that it was speed, not time, which was responsible for these effects. These results suggest that representations of basic expressions of emotion encode information about dynamic as well as static properties.

Effect of antithrombin III on glycoprotein Ib/IX/V activation in human platelets: suppression of thromboxane A2 generation.

We have previously shown that ristocetin, an activator of glycoprotein Ib/IX/V, induces release of soluble CD40 (sCD40) ligand via thromboxane (TX) A(2) production from human platelets. In the present study, we investigated the effect of antithrombin-III (AT-III), an anticoagulant, on the ristocetin-induced glycoprotein Ib/IX/V activation in human platelets. AT-III inhibited ristocetin-stimulated platelet aggregation. The ristocetin-induced production of 11-dehydro-TXB(2), a stable metabolite of TXA(2), and the release of sCD40 ligand were suppressed by AT-III. AT-III also reduced the ristocetin-stimulated secretion of platelet-derived growth factor (PDGF)-AB. AT-III failed to affect U46619-, a TXA(2) receptor agonist, induced levels of p38 mitogen-activated protein kinase phosphorylation or sCD40 ligand release. AT-III reduced the binding of SZ2, a monoclonal antibody to the sulfated sequence in the α-chain of glycoprotein Ib, to the ristocetin-stimulated platelets. These results strongly suggest that AT-III reduced ristocetin-stimulated release of sCD40 ligand due to inhibiting TXA(2) production in human platelets.

cAMP regulates ADP-induced HSP27 phosphorylation in human platelets.

Elevation of cAMP in platelets is recognized to play a suppressive role in platelet functions. We have previously shown that adenosine diphosphate (ADP)-induced phosphorylation of heat shock protein 27 (HSP27) via p38 mitogen-activated protein (MAP) kinase is correlated with platelet-derived growth factor (PDGF)-AB secretion and soluble CD40 ligand (sCD40L) release. In the present study, we investigated the relationship between cAMP and HSP27 phosphorylation in platelet function. 8-Bromoadenosine-3',5'-cyclic monophosphate (8-bromo-cAMP), a plasma membrane-permeable cAMP analogue, or cilostazol, an inhibitor of cAMP phosphodiesterase, markedly attenuated the ADP-induced phosphorylation levels of p38 MAP kinase. In addition, the ADP-induced HSP27 phosphorylation was suppressed by 8-bromo-cAMP or cilostazol. 8-Bromo-cAMP, forskolin and cilostazol remarkably reduced the ADP-stimulated PDGF-AB secretion and sCD40L release. These results strongly suggest that cAMP regulates ADP-stimulated platelet activation due to inhibition of HSP27 phosphorylation via p38 MAP kinase.

Continuous cardiac output measurement with a Doppler-equipped pulmonary artery catheter.

BACKGROUND: We developed a Doppler-equipped pulmonary artery catheter that provides continuous measurement of the true main pulmonary blood flow velocity independent of the angle of incidence formed by the pulmonary artery catheter and the main pulmonary artery blood flow. This device uses 2 orthogonally positioned Doppler transducers that allow trigonometric correction for differences in the angle of blood flow between each transducer. We tested the accuracy of the Doppler-equipped pulmonary artery catheter by comparing its cardiac output measurements with those done by conventional techniques in animals. METHODS: The Doppler-equipped pulmonary artery catheter was evaluated in dogs. A pair of ultrasound Doppler transducers positioned at a fixed angle (90°) was mounted on the distal part of the thermodilution pulmonary artery catheter. The Doppler shifts (Δf1, Δf2) were detected by the 2 transducers sampling at 2 closely spaced points in the main pulmonary artery. The values of Δf1 and Δf2 were used to compute 2 velocity measurements. The true flow velocity of the main pulmonary artery was calculated with the following equation: V(pulm) = {(V(transducer1))(2) + (V(transducer2))(2)}(1/2) (V(pulm) = true main pulmonary artery velocity; V(transducer1) and V(transducer2) = velocity detected by transducers 1 and 2, respectively). The flow velocities were calculated by using a phase differential technique. Cardiac output was calculated as V(pulm) multiplied by a coefficient value. The coefficient value was calculated by dividing cardiac output, derived from conventional techniques, by V(pulm) at the beginning of each experiment. After thoracotomy, an electromagnetic flowprobe was placed around the main pulmonary artery in dogs. Cardiac output was simultaneously measured by the Doppler-equipped pulmonary artery catheter (CO-Doppler), and the electromagnetic flowmeter (CO-EMF) or the thermodilution technique (CO-Thermo). Cardiac output was manipulated by dobutamine and propranolol. RESULTS: CO-Doppler was highly correlated with CO-EMF (y = 1.16 × -0.26, r(2) = 0.99, P < 0.001) and CO-Thermo (y = 1.24 × -0.90, r(2) = 0.85, n = 48, P < 0.001). The bias between CO-EMF and CO-Doppler was -0.02 L/min; 95% limits of agreement were -0.32 to 0.28 L/min. The percentage error was 16%. The bias between CO-Thermo and CO-Doppler was 0.18 L/min; 95% limits of agreement were -0.62 to 0.98 L/min. CONCLUSIONS: The newly developed Doppler-equipped pulmonary artery catheter with 2 orthogonally positioned Doppler transducers allowed accurate and continuous measurements of cardiac output independent of the angle of incidence formed by the pulmonary artery catheter and the main pulmonary artery blood flow.

Antithrombin III reduces collagen-stimulated granule secretion of PDGF-AB and the release of soluble CD40 ligand from human platelets.

Although antithrombin-III (AT-III), an anti-coagulant, has been shown to affect human platelet functions, the direct effect of AT-III on platelets is still unknown. We recently reported that the collagen-induced phosphorylation of the heat shock protein 27 (HSP27) via the p44/p42 mitogen-activated protein (MAP) kinase is sufficient for granule secretion and the release of soluble CD40 ligand (sCD40L) from platelets but not platelet aggregation. In the present study, we investigated whether AT-III affects the collagen-induced secretion of the platelet-derived growth factor (PDGF)-AB and sCD40L release. AT-III inhibited collagen-stimulated platelet aggregation. The collagen-induced secretion of PDGF-AB was significantly suppressed by AT-III. AT-III also reduced sCD40L release. AT-III markedly attenuated the collagen-induced phosphorylated levels of p44/p42 MAP kinase. In addition, AT-III suppressed collagen-induced HSP27 phosphorylation. These results strongly suggest that AT-III reduced collagen-stimulated platelet granule secretion due to the inhibition of HSP27 phosphorylation via p44/p42 MAP kinase.

Mechanism of collagen-induced release of 5-HT, PDGF-AB and sCD40L from human platelets: role of HSP27 phosphorylation via p44/p42 MAPK.

Collagen plays a crucial role in hemostasis and thrombosis by activating platelets and reportedly induces the phosphorylation of heat shock protein (HSP) 27 in human platelets. However, the exact role of HSP27 phosphorylation in human platelets has not yet been clarified. In the present study, we investigated the mechanism of collagen-induced HSP27 phosphorylation and the role in human platelets. The collagen-effect on the phospholylation of HSP27 was dose-dependent in the range between 0.03 and 1.0 microg/ml. The phosphorylation of p44/p42 mitogen-activated protein kinase (MAPK) was also stimulated by collagen. PD98059, a specific inhibitor of MAPK kinase (MEK1/2), reduced collagen-induced HSP27 phosphorylation as well as p44/p42 MAPK phosphorylation. PD98059 significantly suppressed collagen-induced releases of serotonin (5-HT), platelet-derived growth factor (PDGF)-AB and soluble CD40 ligand (sCD40L) while it had little effect on the platelet aggregation. These results strongly suggest that the collagen-induced phosphorylation of HSP27 via p44/p42 MAPK is sufficient for releases of 5-HT, PDGF-AB and sCD40L from human platelets.

Thromboxane A(2) promotes soluble CD40 ligand release from human platelets.

OBJECTIVE: The plasma level of soluble CD40 ligand (sCD40L), which induces pro-inflammatory and pro-atherogenic responses, is known to be elevated in atherosclerotic patients. In this study, we investigated the mechanism of sCD40L release from human platelets, focusing on the involvement of thromboxane (TX) A(2). METHODS: We measured sCD40L release and TXA(2) production induced by ristocetin, an activator of GPIb/IX/V, from human platelets in vitro. Moreover, plasma sCD40L and TXA(2) levels in the 10 patients with severe carotid artery stenosis who were not taking any anti-platelet medicines were measured and compared with those obtained from non-atherosclerotic controls. RESULTS: Ristocetin significantly promoted sCD40L release and TXA(2) generation from platelets in vitro. Aspirin and SC-560, a cyclooxygenase-1 inhibitor, suppressed the ristocetin-induced sCD40L release from platelets in parallel with TXA(2) production. Ozagrel, a TXA(2) synthase inhibitor and PTXA(2), a thromboxane receptor (TP) antagonist also suppressed sCD40L release. U46619, a TP agonist, reversed the suppressive effect of aspirin on sCD40L release. In vivo, plasma levels of sCD40L and TXA(2) in the patients were significantly higher than those in controls. Elevated plasma levels of TXA(2) and sCD40L in the patients were markedly diminished after 7 days of 100mg aspirin administration. CONCLUSION: These results strongly suggest that GPIb/IX/V activation induces sCD40L release via TXA(2) from human platelets, and that sCD40L release via TXA(2) generation from platelets in atherosclerotic patients are up-regulated.

Collagen-induced p38 MAP kinase activation is a biomarker of platelet hyper-aggregation in patients with diabetes mellitus.

AIMS: We developed a novel method for diagnosing platelet hyper-aggregation in patients with type 2 diabetes mellitus (DM). MAIN METHODS: By measuring the dose response of platelet aggregation to collagen, an individual ED(50) was determined. Based on the normal range identified in non-DM controls (mean+/-two SEM=0.460+/-0.082 microg/ml, n=47), type 2 DM patients were divided into high ED(50) (ED(50)>0.542 microg/ml; n=32: group I) or low ED(50) groups (ED(50)<0.378 microg/ml; n=32; group II). In these patients, collagen-induced levels of phospho-p38 MAPK and phospho-p44/p42 MAPK were measured using Western blots and enzyme-linked immunosorbent assays (ELISA). KEY FINDINGS: In group II, the collagen (0.3 and 1 microg/ml)-induced levels of both phospho-p38 MAPK and phospho-p44/p42 MAPK measured by western blot analysis were found to be significantly higher than those in group I. The individual ED(50) was found to be significantly correlated with the collagen-induced levels of phospho-p38 MAPK and phospho-p44/p42 MAPK. This correlation was also observed when ELISA was used to measure phospho-p38 MAPK levels in a different population of DM patients (n=90). SIGNIFICANCE: These results strongly suggest that the phosphorylation levels of collagen-induced p38 MAPK and p44/p42 MAPK represent the hyperaggregability of platelets and that the quantification of phospho-p38 MAPK can be a new and useful diagnostic biomarker of platelet hyper-aggregation in DM patients.

Antithrombin III suppresses ADP-induced platelet granule secretion: inhibition of HSP27 phosphorylation.

Antithrombin III (AT-III), an anti-coagulant, has recently been reported to directly affect human platelet functions. However, the exact mechanism of AT-III in platelets remains to be clarified. We have previously shown that adenosine diphosphate (ADP)-induced phosphorylation of heat shock protein 27 (HSP27) via p44/p42 mitogen-activated protein kinase (MAPK) and p38 MAPK is correlated with platelet granule secretion. In the present study, we investigated the relationship between AT-III and the ADP-induced platelet granule secretion. The ADP-induced secretion of platelet-derived growth factor (PDGF)-AB and serotonin (5-HT) were significantly suppressed by AT-III. The ADP-induced soluble CD40 ligand (sCD40L) release was inhibited by either PD98059, a MEK inhibitor, or SB203580, a p38 MAPK inhibitor. AT-III also inhibited the sCD40L release. AT-III markedly attenuated the ADP-induced phosphorylation levels of p44/p42 MAPK and p38 MAPK. Furthermore, the ADP-induced HSP27 phosphorylation was suppressed by AT-III. These results strongly suggest that AT-III directly acts on platelets and suppresses ADP-induced platelet granule secretion due to inhibiting HSP27 phosphorylation via p44/p42 MAPK and p38 MAPK.

The association between the initial end-tidal carbon dioxide difference and the lowest arterial oxygen tension value obtained during one-lung anesthesia with propofol or sevoflurane.

OBJECTIVE: The purpose of this study was to examine the correlation between the lowest PaO(2) value recorded during the first 45 minutes of one-lung ventilation (OLV) and the end-tidal CO(2) (ETCO(2)) difference between two-lung ventilation (TLV) and the early phase of OLV. DESIGN: A prospective, randomized study. SETTING: A university hospital. PARTICIPANTS: Thirty-six patients scheduled for elective thoracic surgery. INTERVENTIONS: Thoracic surgery patients were randomly assigned to 1 of 2 groups (group P [n = 18], maintained with propofol; group S [n = 18], maintained with sevoflurane). After setting up, the authors measured arterial blood gases at F(I)O(2) = 1.0 as follows: during TLV and at 5 minutes, 15 minutes, 30 minutes, and 45 minutes after the start of OLV. ETCO(2) was recorded just before and at 3 minutes after the start of OLV. The authors examined the relationship between the initial ETCO(2) difference and the lowest PaO(2) value recorded during the first 45 minutes of OLV. MEASUREMENTS AND MAIN RESULTS: There was a significant negative correlation between the lowest PaO(2) (x) value and the initial ETCO(2) difference (y) during OLV in each group (group P: y = -0.0203x + 7.2571, r(2) = 0.5351; group S: y = -0.0257x + 7.3158, r(2) = 0.6129). This correlation was not significantly different between the groups. CONCLUSION: The present study indicates that the ETCO(2) difference between TLV and early OLV has an association with impaired oxygenation later during OLV. This would be a simple and clinically convenient predictor of the lowest PaO(2) value likely to be reached during one-lung anesthesia with either propofol or sevoflurane.