Fumika Sakuraya

Normalization by edaravone, a free radical scavenger, of irradiation-reduced endothelial nitric oxide synthase expression

We investigated the therapeutic effect of edaravone, a free radical scavenger, on alterations in endothelium-dependent relaxation and endothelial nitric oxide synthase (eNOS) expression in the rabbit ear central artery at 2 weeks after exposure to a dose of 45 Gy radiation with a cobalt60 unit. For treatment with edaravone, edaravone was given daily to the animals from the day before irradiation at an intrapenetreal dose of 10 mg/kg twice a day. The endothelium-dependent relaxant response to acetylcholine was markedly impaired in irradiated vessels. Edaravone treatment improved the response to the level observed in nonirradiated control vessels. Using immunohistochemical and Western blot techniques, we showed that protein expression of eNOS in irradiated vessels was reduced to about 50% of control and that edaravone treatment returned it nearly to intact levels. Gene expression of eNOS, analyzed by reverse transcription-competitive polymerase chain reaction, was found to be reduced from the control level by 47% following irradiation. The reduced level of eNOS mRNA in irradiated vessels was almost completely normalized by edaravone treatment. These results suggest that edaravone has a protective effect on the reduced expression of eNOS and its associated endothelial cell dysfunction in the vessels following irradiation. We thus assume that oxygen-free radicals may be closely related to the irradiation-induced derangement of the eNOS gene regulation.

Chronological expression of PAR isoforms in acute liver injury and its amelioration by PAR2 blockade in a rat model of sepsis

The liver can be injured and its functions altered by activation of the coagulation and inflammatory processes in sepsis. The objective of the present study was to investigate the pattern of protease- activated receptors (PARs) over time in a model of acute liver injury induced by lipopolysaccharide (LPS); and whether PARs play a role in this process and exert their effects through inflammation and coagulation. Levels of tumor necrosis factor-a (TNF-a) were significantly expressed 1 h after LPS administration followed by: i) an increase in levels of tissue factor, factor VIIa, thrombin and plasminogen activator inhibitor-1; ii) unchanged or steady levels of tissue factor pathway inhibitor; and iii) subsequent deposition of fibrin in the liver tissue, that led to the elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), which are associated with liver injury. The expression of all PAR isoforms (1-4) was elevated, and each isoform had a distinct cellular localization (hepatocytes, Kupffer cells, the portal triad area, and central veins) and a time-dependent pattern of expression. The immuno-reactivity of PAR2 and 4 in Kupffer cells was intense. Interestingly, PAR2 blocking peptide improved the healing of liver injuries, an effect that was associated with suppression of TNF-a elevation, and normalization of coagulation and fibrinolysis. This ultimately led to decreased fibrin formation in the injured liver. The present study reveals a distinct chronological expression and cellular localization of PARs in LPS-mediated liver injury and shows that blockade of PAR2 may play a crucial role in treating liver injury, via normalization of inflammation, coagulation and fibrinolytic pathways.

Protein kinase C modulation of the regulation of sarcoplasmic reticular function by protein kinase A-mediated phospholamban phosphorylation in diabetic rats.

The goal of this study was to elucidate the possible mechanisms by which protein kinase A (PKA)‐mediated regulation of the sarcoplasmic reticulum (SR) via phospholambin protein phosphorylation is functionally impaired in streptozotocin‐induced diabetic rats. Phospholamban (PLB) protein and mRNA levels were 1.3‐fold higher in diabetic than in control hearts, while protein expression of cardiac SR Ca2+‐ATPase (SERCA2a) was unchanged. Basal and isoprenaline‐stimulated phosphorylation of PLB at Ser16 or Thr17 was unchanged in diabetic hearts. However, stronger immunoreactivity was observed at the basal level in diabetic hearts when antiphosphoserine antibody was used. Basal 32P incorporation into PLB was significantly higher in diabetic than in control SR vesicles, but the extent of the PKA‐mediated increase in PLB phosphorylation was the same in the two groups of vesicles. Stimulation of Ca2+ uptake by PKA‐catalyzed PLB phosphorylation was weaker in diabetic than in control SR vesicles. The PKA‐induced increase in Ca2+ uptake was attenuated when control SR vesicles were preincubated with protein kinase C (PKC). PKC activities were increased by more than two‐fold in the membranous fractions from diabetic hearts in comparison with control values, regardless of whether Ca2+ was present. This was associated with increases in the protein content of PKCδ, PKCη, PKCι, and PKCλ in diabetic membranous fractions. The changes observed in diabetic rats were reversed by insulin therapy. These results suggest that PKA‐dependent phosphorylation may incompletely counteract the function of PLB as an inhibitor of SERCA2a activity in diabetes in which PKC expression and activity are enhanced.

Comparison of the analgesic efficacy of ultrasound‐guided rectus sheath block and local anesthetic infiltration for laparoscopic percutaneous extraperitoneal closure in children

Ultrasound‐guided rectus sheath block and local anesthetic infiltration are the standard options to improve postoperative pain for children undergoing surgery with a midline incision. However, there is no study comparing the effect of ultrasound‐guided rectus sheath block with local anesthetic infiltration for children undergoing laparoscopic surgery.

Gastric intramucosal perfusion during descending aortic repair under femoro-femoral bypass.

The changes in gastric mucosal perfusion during distal aortic perfusion with femoro-femoral bypass (F-F bypass) were assessed by air-automated gastric tonometry. A prospective study was performed in six patients who underwent descending aortic surgery for aortic aneurysm under F-F bypass with mild hypothermia (34°C). Gastric intramucosal pH (pHi) and PaCO2-PgCO2 gap (PCO2 gap) were measured. Data are presented as means and standard deviations and analyzed by using one-way analysis of variance followed by Scheffe test. Perioperative variables of hepatorenal functions are also evaluated. The PCO2 gap significantly increased during F-F bypass (3.0 ± 2.1 mm Hg at control, 14.2 ± 5.5 mm Hg during F-F bypass; p = 0.004), indicating abnormal gastric mucosal perfusion during F-F bypass. Significantly low pHi was found at weaning from F-F bypass (7.35 ± 0.05 at control, 7.21 ± 0.10 at weaning; p = 0.009), which might be related to progressing systemic metabolic acidosis. No impairment of hepatorenal functions was observed after the surgery. Distal perfusion with F-F bypass during descending aortic surgery could impair the gastric mucosal perfusion, but may have little effect on postoperative visceral dysfunction.