FUT2 non-secretor status is associated with Type 1 diabetes susceptibility in Japanese children

AIM

To examine the contribution of the FUT2 gene and ABO blood type to the development of Type 1 diabetes in Japanese children.

METHODS

We analysed FUT2 variants and ABO genotypes in a total of 531 Japanese children diagnosed with Type 1 diabetes and 448 control subjects. The possible association of FUT2 variants and ABO genotypes with the onset of Type 1 diabetes was statistically examined.

RESULTS

The se2 genotype (c.385A>T) of the FUT2 gene was found to confer susceptibility to Type 1A diabetes in a recessive effects model [odds ratio for se2/se2, 1.68 (95% CI 1.20-2.35); corrected P value = 0.0075].

CONCLUSIONS

The FUT2 gene contributed to the development of Type 1 diabetes in the present cohort of Japanese children.

Development of a new biodegradable operative clip made of a magnesium alloy: Evaluation of its safety and tolerability for canine cholecystectomy

BACKGROUND

Operative clips used to ligate vessels in abdominal operation usually are made of titanium. They remain in the body permanently and form metallic artifacts in computed tomography images, which impair accurate diagnosis. Although biodegradable magnesium instruments have been developed in other fields, the physical properties necessary for operative clips differ from those of other instruments. We developed a biodegradable magnesium-zinc-calcium alloy clip with good biologic compatibility and enough clamping capability as an operative clip. In this study, we verified the safety and tolerability of this clip for use in canine cholecystectomy.

METHODS

Nine female beagles were used. We performed cholecystectomy and ligated the cystic duct by magnesium alloy or titanium clips. The chronologic change of clips and artifact formation were compared at 1, 4, 12, 18, and 24 weeks postoperative by computed tomography. The animals were killed at the end of the observation period, and the clips were removed to evaluate their biodegradability. We also evaluated their effect on the living body by blood biochemistry data.

RESULTS

The magnesium alloy clip formed much fewer artifacts than the titanium clip, and it was almost absorbed at 6 months postoperative. There were no postoperative complications and no elevation of constituent elements such as magnesium, calcium, and zinc during the observation period in both groups.

CONCLUSION

The novel magnesium alloy clip demonstrated sufficient sealing capability for the cystic duct and proper biodegradability in canine models. The magnesium alloy clip revealed much fewer metallic artifacts in CT than the conventional titanium clip.

Pathophysiology of Venous Thromboembolism with Respect to the Anatomical Features of the Deep Veins of Lower Limbs: A Review

Here the pathophysiology of venous thromboembolism is reviewed with respect to the anatomical features of the deep veins of lower limbs. A thrombus is less likely to form in the thigh veins compared with that in the calf veins; however, clinical symptoms are more likely to appear in the thigh veins owing to vascular occlusion. When a patient is bedridden, thrombosis is more likely to occur in the intramuscular vein, which mainly depends on muscular pumping and the venous valve, rather than in the three crural branches, which mainly depends on the pulsation of the accompanying artery. Thrombi are prone to be generated in the soleal vein compared with those in the gastrocnemius vein because of the vein and muscle structures. A soleal vein thrombosis grows toward the proximal veins along the drainage veins. To prevent a sudden pulmonary thromboembolism-related death in bedridden patients, preventing soleal vein thrombus formation and observing the thrombus proximal propagation via the drainage veins are clinically important. When deep vein thrombosis occurs, avoiding embolization and sequela caused by the thrombus organization is necessary.

Variants associated with autoimmune Type 1 diabetes in Japanese children: implications for age-specific effects of cis-regulatory haplotypes at 17q12-q21

AIMS

The aim of this study was to clarify the significance of previously reported susceptibility variants in the development of autoimmune Type 1 diabetes in non-white children. Tested variants included rs2290400, which has been linked to Type 1 diabetes only in one study on white people. Haplotypes at 17q12-q21 encompassing rs2290400 are known to determine the susceptibility of early-onset asthma by affecting the expression of flanking genes.

METHODS

We genotyped 63 variants in 428 Japanese people with childhood-onset autoimmune Type 1 diabetes and 457 individuals without diabetes. Possible association between variants and age at diabetes onset was examined using age-specific quantitative trait locus analysis and ordered-subset regression analysis.

RESULTS

Ten variants, including rs2290400 in GSDMB, were more frequent among the people with Type 1 diabetes than those without diabetes. Of these, rs689 in INS and rs231775 in CTLA4 yielded particularly high odds ratios of 5.58 (corrected P value 0.001; 95% CI 2.15-14.47) and 1.64 (corrected P value 5.3 × 10^-5 ; 95% CI 1.34-2.01), respectively. Age-specific effects on diabetes susceptibility were suggested for rs2290400; heterozygosity of the risk alleles was associated with relatively early onset of diabetes, and the allele was linked to the phenotype exclusively in the subgroup of age at onset ≤ 5.0 years.

CONCLUSIONS

The results indicate that rs2290400 in GSDMB and polymorphisms in INS and CTLA4 are associated with the risk of Type 1 diabetes in Japanese children. Importantly, cis-regulatory haplotypes at 17q12-q21 encompassing rs2290400 probably determine the risk of autoimmune Type 1 diabetes predominantly in early childhood.

In vivo corrosion behaviour of magnesium alloy in association with surrounding tissue response in rats

Biodegradable magnesium (Mg) alloys are the most promising candidates for osteosynthesis devices. However, their in vivo corrosion behaviour has not been fully elucidated. The aim of this study was to clarify the influence of the physiological environment surrounding Mg alloys on their corrosion behaviour. A Mg-1.0Al alloy with a fine-grained structure was formed into plates using titanium (Ti) as a control. These plates were implanted into the subperiosteum in the head, subcutaneous tissue of the back, and in the muscle of the femur of rats for 1, 2 and 4 weeks. The volumes of the remaining Mg alloy and of the insoluble salt deposition and gas cavities around the Mg alloy were determined by microtomography, and the volume losses were calculated. Then, the tissue response around the plates in each implantation site was examined histopathologically, and its relation to the respective volume loss was analyzed. These analyses determined that the Mg alloy was corroded fastest in the head, at an intermediate level in the back, and slowest in the femur. The insoluble salt deposition at the Mg alloy surface had no influence on the volume loss. Gas cavities formed around the Mg alloy at all implantation sites and decreased after 4 weeks. Histopathological examination revealed that the Mg alloy exhibited good biocompatibility, as was seen with Ti. In addition, vascularized fibrous capsules formed around the plates and became mature with time. Notably, the volume loss in the different anatomical locations correlated with capsule thickness. Together, our results suggest that, to facilitate the successful clinical application of Mg alloys, it will be necessary to further comprehend their interactions with specific in vivo environments.

Fabrication of a magnesium alloy with excellent ductility for biodegradable clips

To develop a biodegradable clip, the equivalent plastic strain distribution during occlusion was evaluated by the finite element analysis (FEA) using the material data of pure Mg. Since the FEA suggested that a maximum plastic strain of 0.40 is required to allow the Mg clips, the alloying of magnesium with essential elements and the control of microstructure by hot extrusion and annealing were conducted. Mechanical characterization revealed that the Mg-Zn-Ca alloy obtained by double extrusion followed by annealing at 673K for 2h possessed a fracture strain over 0.40. The biocompatibility of the alloy was confirmed here by investigating its degradation behavior and the response of extraperitoneal tissue around the Mg-Zn-Ca alloy. Small gas cavity due to degradation was observed following implantation of the developed Mg-Zn-Ca clip by in vivo micro-CT. Histological analysis, minimal observed inflammation, and an only small decrease in the volume of the implanted Mg-Zn-Ca clip confirmed its excellent biocompatibility. FEA using the material data for ductile Mg-Zn-Ca also showed that the clip could occlude the simulated vessel without fracture. In addition, the Mg-Zn-Ca alloy clip successfully occluded the renal vein. Microstructural observations using electron backscattering diffraction confirmed that dynamic recovery occurred during the later stage of plastic deformation of the ductile Mg-Zn-Ca alloy. These results suggest that the developed Mg-Zn-Ca alloy is a suitable material for biodegradable clips.

STATEMENT OF SIGNIFICANCE

Since conventional magnesium alloys have not exhibited significant ductility for applying the occlusion of vessels, the alloying of magnesium with essential elements and the control of microstructure by hot extrusion and annealing were conducted. Mechanical characterization revealed that the Mg-Zn-Ca alloy obtained by double extrusion followed by annealing at 673K for 2h possessed a fracture strain over 0.40. The biocompatibility of the alloy was confirmed by investigating its degradation behavior and the response of extraperitoneal tissue around the Mg-Zn-Ca alloy. Finite element analysis using the material data for the ductile Mg-Zn-Ca alloy also showed that the clip could occlude the simulated vessel without fracture. In addition, the Mg-Zn-Ca alloy clip successfully occluded the renal vein. Microstructural observations using electron backscattering diffraction confirmed that dynamic recovery occurred during the later stage of plastic deformation of the ductile Mg-Zn-Ca alloy.

Different mechanisms of hydroxyl radical production susceptible to purine P2 receptor antagonists between carbon monoxide poisoning and exogenous ATP in rat striatum

Previous studies have suggested that carbon monoxide (CO) poisoning stimulates cAMP production via purine P2Y11-like receptors in the rat striatum, activating cAMP signaling pathways, resulting in hydroxyl radical ((•)OH) production. Extracellular ATP was thought likely to trigger the cascade, but the present study has failed to demonstrate a clear increase in the extracellular ATP due to CO poisoning. The CO-induced (•)OH production was attenuated by the P2Y11 receptor antagonist NF157, in parallel with its abilities to suppress the CO-induced cAMP production. The (•)OH production was more strongly suppressed by a non-selective P2 receptor antagonist, PPADS, which had no effect on cAMP production. More selective antagonists toward the respective P2 receptors susceptible to PPADS, including NF279, had little or no effect on the CO-induced (•)OH production. The intrastriatal administration of exogenous ATP dose-dependently stimulated (•)OH production, which was dose-dependently antagonized by PPADS and NF279 but not by NF157. Exogenous GTP and CTP dose-dependently stimulated (•)OH production, though less potently. The GTP-induced (•)OH production was susceptible to both of NF279 and PPADS, but the CTP-induced (•)OH production was resistant to PPADS. The mechanism of (•)OH production may differ between CO poisoning and exogenous ATP, while multiple P2 receptors could participate in (•)OH production. The CO-induced (•)OH production was susceptible to the inhibition of NADPH oxidase, but not xanthine oxidase. Also, the NADPH oxidase inhibition suppressed (•)OH production induced by forskolin, a stimulator of intracellular cAMP formation. It is likely that (•)OH is produced by NADPH oxidase activation via cAMP signaling pathways during CO poisoning.

Autosomal recessive cystinuria caused by genome-wide paternal uniparental isodisomy in a patient with Beckwith-Wiedemann syndrome

Approximately 20% of Beckwith-Wiedemann syndrome (BWS) cases are caused by mosaic paternal uniparental disomy of chromosome 11 (pUPD11). Although pUPD11 is usually limited to the short arm of chromosome 11, a small minority of BWS cases show genome-wide mosaic pUPD (GWpUPD). These patients show variable clinical features depending on mosaic ratio, imprinting status of other chromosomes, and paternally inherited recessive mutations. To date, there have been no reports of a mosaic GWpUPD patient with an autosomal recessive disease caused by a paternally inherited recessive mutation. Here, we describe a patient concurrently showing the clinical features of BWS and autosomal recessive cystinuria. Genetic analyses revealed that the patient has mosaic GWpUPD and an inherited paternal homozygous mutation in SLC7A9. This is the first report indicating that a paternally inherited recessive mutation can cause an autosomal recessive disease in cases of GWpUPD mosaicism. Investigation into recessive mutations and the dysregulation of imprinting domains is critical in understanding precise clinical conditions of patients with mosaic GWpUPD.

InGaN/GaN/AlGaN-Based Leds and Laser Diodes

InGaN quantum-well-structure blue LEDs were grown on epitaxially laterally overgrown GaN (ELOG) and sapphire substrates. The output power of both LEDs was as high as 6 mW at a current of 20 mA. The LED on sapphire had a considerable amount of leakage current in comparison with that on ELOG. These results indicate that In composition fluctuation is not caused by threading dislocations (TDs), free carriers are captured by radiative recombination centers before they are captured by nonradiative recombination centers in InGaN, and that the dislocations form the leakage current pathway in InGaN. Red LED with an emission peak wavelength of 650 nm was fabricated by increasing the In composition and thickness of InGaN well layer. When the laser diodes (LD) was formed on the GaN layer above the SiO2 mask region, the threshold current density was as low as 3 kAcm−2. When the LD was formed on the window region, the threshold current density was as high as 6 to 9 kAcm−2. There is a possibility that a leakage current due to a large number of TDs caused the high threshold current density on the window region. InGaN multi-quantum-well (MQW) structure LDs grown on the ELOG substrate showed an output power as high as 420 mW under RT-CW operation. The longest lifetime of 9,800 hours at a constant output power of 2 mW was achieved. The InGaN MQW LDs were fabricated on a GaN substrate. The fundamental transverse mode was observed up to an output power of 80 mW.

Endoscopic ultrasound-guided celiac ganglia neurolysis vs. celiac plexus neurolysis: a randomized multicenter trial

BACKGROUND AND STUDY AIMS

No prospective comparison of endoscopic ultrasonography-guided direct celiac ganglia neurolysis (EUS - CGN) vs. EUS-guided celiac plexus neurolysis (EUS - CPN) has been reported. The aim of the current study was to compare the effectiveness of EUS - CGN and EUS - CPN in providing pain relief from upper abdominal cancer pain in a multicenter randomized controlled trial.

PATIENTS AND METHODS

Patients with upper abdominal cancer pain were randomly assigned to treatment using either EUS - CGN or EUS - CPN. Evaluation was performed at Day 7 postoperatively using a pain scale of 0 to 10. Patients for whom pain decreased to ≤ 3 were considered to have a positive response, and those experiencing a decrease in pain to ≤ 1 were considered to be completely responsive. Comparison between the two groups was performed using intention-to-treat analysis. The primary endpoint was the difference in treatment response rates between EUS - CGN and EUS - CPN at postoperative Day 7. Secondary endpoints included differences in complete response rates, pain scores, duration of pain relief, and incidence of adverse effects.

RESULTS

A total of 34 patients were assigned to each group. Visualization of ganglia was possible in 30 cases (88 %) in the EUS - CGN group. The positive response rate was significantly higher in the EUS - CGN group (73.5 %) than in the EUS - CPN group (45.5 %; P = 0.026). The complete response rate was also significantly higher in the EUS - CGN group (50.0 %) than in the EUS - CPN group (18.2 %; P = 0.010). There was no difference in adverse events or duration of pain relief between the two groups.

CONCLUSIONS

EUS - CGN is significantly superior to conventional EUS - CPN in cancer pain relief.

CLINICAL TRIAL REGISTRATION

http://www.umin.ac.jp/ctr/index.htm (ID: UMIN-000002536).

Forensic identification using multiple lot numbers of an implanted device

We report a case in which identification of a deceased individual was established using multiple lot numbers printed on a body implantable device. Autopsy of an unknown woman revealed an intramedullary nail inserted within her right femur. The device manufacturer was identified from the configuration of the intramedullary nail, and the "use history" was traced from lot numbers printed on the device's multiple parts. The deceased individual was thus identified as a woman who had attempted suicide by jumping from a height about a year previously and had been transported to a hospital and undergone surgery that included implantation of the intramedullary nail. The main factor contributing to the rapid identification was the manufacturer's and distributor's record of the use history (traceability) of the product, because of their accountability for purposes of quality control. A second contributing factor was multiple lot numbers, resulting in extremely low probability of the same combination of lot numbers being present in multiple individuals. This case confirmed the utility of multiple lot numbers of body implantable devices in forensic identification.

Fabrication of Y2O3-Doped Zirconia/Gadolinia-Doped Ceria Bilayer Electrolyte Thin Film SOFC Cells of SOFCs by Single-Pulsed Laser Deposition Processing

An 8 -mol. % Y₂O₃-doped zirconia/10-mol. % GdO₂-doped ceria (YSZ/GDC) bilayer electrolyte and a Gd_0.5Sr_0.5CoO₃ (GSCO) cathode were deposited by a single-processing, pulsed laser deposition (PLD) method to fabricate anode support cells. No additional heat treatment was needed. Laser frequencies of 10, 20, and 100 Hz were used to deposit bilayer electrolytes between the NiO–YSZ (NiO:YSZ = 60:40 wt. %) anode substrate and the GSCO cathode thin film. The GDC thin film produced at 10 Hz was smooth, well-crystallized, and highly dense. The crystallinity of the GSCO cathode on the GDC was also improved. We concluded the GDC crystallinity affected the crystallinity of the cathode thin film. The resistivity of the YSZ single layer (5.7 μm thickness) was 1.4 times higher than that of the YSZ/GDC bilayer (YSZ 3.0 μm thickness, GDC 2.7 μm thickness) at 600 °C and that of the YSZ-GDC interface became low. The optimum YSZ thickness was found to be approximately 3.0 μm, at which thickness there was effective blocking of the passage of hydrogen molecules and electrons. A cell with a YSZ (3.0 μm thickness, fabricated at 20 Hz)/GDC (5.0 μm thickness, fabricated at 10 Hz) bilayer and GSCO cathode thin film exhibited a maximum power density of 400 mW·cm^–2 at a comparatively low temperature of 600 °C.

Japanese multicenter experience of endoscopic necrosectomy for infected walled-off pancreatic necrosis: The JENIPaN study

BACKGROUND AND STUDY AIMS

Only a few large cohort studies have evaluated the efficacy and safety of endoscopic necrosectomy for infected walled-off pancreatic necrosis (WOPN). Therefore, a multicenter, large cohort study was conducted to evaluate the efficacy and safety of endoscopic necrosectomy and to examine the procedural details and follow-up after successful endoscopic necrosectomy.

PATIENTS AND METHODS

A retrospective review was conducted in 16 leading Japanese institutions for patients who underwent endoscopic necrosectomy for infected WOPN between August 2005 and July 2011. The follow-up data were also reviewed to determine the long-term outcomes of the procedures.

RESULTS

Of 57 patients, 43 (75 %) experienced successful resolution after a median of 5 sessions of endoscopic necrosectomy and 21 days of treatment. Complications occurred in 19 patients (33 %) during the treatment period. Six patients died (11 %): two due to multiple organ failure and one patient each from air embolism, splenic aneurysm, hemorrhage from a Mallory - Weiss tear, and an unknown cause. Of 43 patients with successful endoscopic necrosectomy, recurrent cavity formation was observed in three patients during a median follow-up period of 27 months.

CONCLUSIONS

Endoscopic necrosectomy can be an effective technique for infected WOPN and requires a relatively short treatment period. However, serious complications can arise, including death. Therefore, patients should be carefully selected, and knowledgeable, skilled, and experienced operators should perform the procedure. Further research into safer technologies is required in order to reduce the associated morbidity and mortality.

Japanese multicenter experience of endoscopic necrosectomy for infected walled-off pancreatic necrosis: The JENIPaN study

BACKGROUND AND STUDY AIMS

Only a few large cohort studies have evaluated the efficacy and safety of endoscopic necrosectomy for infected walled-off pancreatic necrosis (WOPN). Therefore, a multicenter, large cohort study was conducted to evaluate the efficacy and safety of endoscopic necrosectomy and to examine the procedural details and follow-up after successful endoscopic necrosectomy.

PATIENTS AND METHODS

A retrospective review was conducted in 16 leading Japanese institutions for patients who underwent endoscopic necrosectomy for infected WOPN between August 2005 and July 2011. The follow-up data were also reviewed to determine the long-term outcomes of the procedures.

RESULTS

Of 57 patients, 43 (75 %) experienced successful resolution after a median of 5 sessions of endoscopic necrosectomy and 21 days of treatment. Complications occurred in 19 patients (33 %) during the treatment period. Six patients died (11 %): two due to multiple organ failure and one patient each from air embolism, splenic aneurysm, hemorrhage from a Mallory - Weiss tear, and an unknown cause. Of 43 patients with successful endoscopic necrosectomy, recurrent cavity formation was observed in three patients during a median follow-up period of 27 months.

CONCLUSIONS

Endoscopic necrosectomy can be an effective technique for infected WOPN and requires a relatively short treatment period. However, serious complications can arise, including death. Therefore, patients should be carefully selected, and knowledgeable, skilled, and experienced operators should perform the procedure. Further research into safer technologies is required in order to reduce the associated morbidity and mortality.

Human organic cation transporter 2 (hOCT2): Inhibitor studies using S2-hOCT2 cells

Highly expressed in kidney and located on the basolateral membrane, human organic cation transporter 2 (hOCT2) can transport various compounds (i.e. drugs and toxins) into the proximal tubular cell. Using cultured proximal tubule cells stably expressing hOCT2 (i.e. S2-hOCT2 cells), we sought to probe different compound classes (e.g. analgesics, anti-depressants, anti-psychotics, disinfectant, herbicides, insecticides, local anesthetic, muscarinic acetylcholine receptor antagonist, sedatives, steroid hormone, stimulants and toxins) for their ability to inhibit (14)C-TEA uptake, a prototypical OCT2 substrate. Aconitine, amitriptyline, atropine, chlorpyrifos, diazepam, fenitrothion, haloperidol, lidocaine, malathion, mianserin, nicotine and triazolam significantly inhibited (14)C-TEA uptake; IC50 values were 59.2, 2.4, 2.0, 20.7, 32.3, 13.2, 32.5, 104.6, 71.1, 17.7, 52.8 and 65.5μM, respectively. In addition, aconitine, amitriptyline, atropine, chlorpyrifos, fenitrothion, haloperidol, lidocaine, and nicotine displayed competitive inhibition with Ki values of 145.6, 2.5, 2.4, 24.8, 16.9, 51.6, 86.8 and 57.7μM, respectively. These in vitro data support the notion that compounds pertaining to a wide variety of different drug classes have the potential to decrease renal clearance of drugs transported via hOCT2. Consequently, these data warrant additional studies to probe hOCT2 and its role to influence drug pharmacokinetics.

Sulfide induces apoptosis and Rho kinase-dependent cell blebbing in Jurkat cells

Hydrogen sulfide (H₂S) is a toxic gaseous substance, and accidental exposure to high concentrations of H₂S has been reported to be lethal to humans. Inhaled and absorbed H₂S is partially dissolved within the circulation and causes toxic effects on lymphocytes. However, the mechanisms involved in H₂S toxicity have not been well documented. In this study, we examined the cellular uptake and injury of sulfide-exposed human T lymphocytes (Jurkat). Cells were exposed to a H₂S donor, sodium hydroxysulfide (NaHS), at pH 6.0, 7.0, or 8.0 for 1 h at 37 °C in a sealed conical tube to avoid the loss of dissolved H₂S gas. Cytotoxicity and cellular sulfide concentrations increased dramatically as the pH of the NaHS solution decreased. Sulfide enhanced the cleavage of caspase-3 and poly (ADP-ribose) polymerase and induced early cellular apoptosis. A pan-caspase inhibitor reduced sulfide-induced apoptosis. These results indicate that sulfide induces pH-dependent and caspase-dependent apoptosis. We also found that blebbing of the plasma membrane occurred in sulfide-exposed cells. Both ROCK-1 and ROCK-2 (Rho kinases) were activated by sulfide, and sulfide-induced cell blebbing was suppressed by a ROCK inhibitor, suggesting that a Rho pathway is involved in sulfide-induced blebbing in lymphocytes.

Peptide inhibitors for angiotensin I-converting enzyme from enzymatic hydrolysates of porcine skeletal muscle proteins

Inhibitors of angiotensin I-converting enzyme (ACE) have been shown to have antihypertensive effects and have been utilized for pharmaceuticals and physiologically functional foods. In the present study, efforts were directed to find ACE inhibitory activities derived from muscle proteins. Porcine skeletal muscle proteins were hydrolyzed by eight proteases, and the inhibitory activities of the hydrolysates toward ACE were measured. Among the digests of the water-insoluble protein fraction prepared from muscle, thermolysin digest demonstrated the highest activity. Also, among hydrolysates of porcine myosin produced by the same enzymes, thermolysin digest showed the most potent inhibitory activity. Two ACE inhibitory peptides were purified from thermolysin digest of myosin. The sequences of these inhibitory peptides, named myopentapeptides A and B, were Met-Asn-Pro-Pro-Lys and Ile-Thr-Thr-Asn-Pro. These sequences were found in the primary structure of the myosin heavy chain. The concentrations of the peptides showing 50% inhibition values (IC(50)) of ACE were 945.5 and 549.0 μM, respectively. Also, six tripeptides, Met-Asn-Pro, Asn-Pro-Pro, Pro-Pro-Lys, Ile-Thr-Thr, Thr-Thr-Asn, and Thr-Asn-Pro, which have parts of the sequences of the myopentapeptides, demonstrated activity. Their IC(50) values were 66.6, 290.5, >1000, 678.2, 672.7, and 207.4 μM, respectively.

Dual contradictory roles of cAMP signaling pathways in hydroxyl radical production in the rat striatum

Studies have suggested that cAMP signaling pathways may be associated with the production of reactive oxygen species. In this study, we examined how modifications in cAMP signaling affected the production of hydroxyl radicals in rat striatum using microdialysis to measure extracellular 2,3-dihydroxybenzoic acid (2,3-DHBA), which is a hydroxyl radical adduct of salicylate. Up to 50 nmol of the cell-permeative cAMP mimetic 8-bromo-cAMP (8-Br-cAMP) increased 2,3-DHBA in a dose-dependent manner (there was no additional increase in 2,3-DHBA at 100 nmol). Another cAMP mimetic, dibutyryl cAMP (db-cAMP), caused a nonsignificant increase in 2,3-DHBA at 50 nmol and a significant decrease at 100 nmol. Up to 20 nmol of forskolin, which is a direct activator of adenylyl cyclase, increased 2,3-DHBA, similar to the effect of 8-Br-cAMP; however, forskolin resulted in a much greater increase in 2,3-DHBA. A potent inhibitor of protein kinase A (PKA), H89 (500 μM), potentiated the 8-Br-cAMP- and forskolin-induced increases in 2,3-DHBA and antagonized the inhibitory effect of 100 nmol of db-cAMP. Interestingly, the administration of 100 nmol of 8-bromo-cGMP alone or in combination with H89 had no significant effect on 2,3-DHBA levels. Doses of 100 nmol of a preferential PKA activator (6-phenyl-cAMP) or a preferential PKA inhibitor (8-bromoadenosine-3',5'-cyclic monophosphorothionate, Rp-isomer; Rp-8-Br-cAMPS), which also inhibits the cAMP-mediated activation of Epac (the exchange protein directly activated by cAMP), suppressed or enhanced, respectively, the formation of 2,3-DHBA. Up to 100 nmol of 8-(4-chlorophenylthio)-2'-O-methyladenosine-cAMP, which is a selective activator of Epac, dose-dependently stimulated the formation of 2,3-DHBA. These findings suggest that cAMP signaling plays contradictory roles (stimulation and inhibition) in the production of hydroxyl radicals in rat striatum by differential actions of Epac and PKA. These roles might contribute to the production of hydroxyl radicals concomitant with cAMP in carbon monoxide poisoning, because the formation of 2,3-DHBA was potentiated by the PKA inhibitor H89 and suppressed by Rp-8-Br-cAMPS, which inhibits PKA and Epac.

Carbon dioxide insufflation vs. conventional saline irrigation for peroral video cholangioscopy

BACKGROUND AND STUDY AIMS

Recent studies have evaluated the efficacy of peroral cholangioscopy (POCS) for diagnosis of biliary diseases. In order to obtain clear images with POCS, saline irrigation, which is performed to replace yellow bile, is carried out for an extended duration. The aim of this study was to evaluate the feasibility of replacing saline irrigation with CO₂ insufflation during POCS.

PATIENTS AND METHODS

A total of 36 patients who had bile duct lesions and were due to undergo POCS were enrolled in the study. Of these patients, 18 underwent POCS using saline irrigation followed by CO₂ insufflation, and 18 patients underwent the reverse approach. The two methods were compared with regard to the time required to obtain a clear endoscopic image and the quality of the images.

RESULTS

The median time required to obtain a clear endoscopic image using CO₂ insufflation (5.0 min) was significantly shorter than that required for saline irrigation (22.5 min; P < 0.001). The quality of the endoscopic images obtained was similar in 27 cases. However, CO₂ insufflation provided better images in four cases that showed an abundance of mucin or biliary sludge, and saline irrigation was superior to CO₂ insufflation in five cases that showed severe stricture with bleeding and tall papillary lesions.

CONCLUSIONS

CO₂ insufflation during POCS can reduce procedure time and simplify cholangioscopy. The overall image quality was similar to that obtained with conventional saline irrigation.