Improving intraoperative diagnosis of spread through air spaces: A cryo-embedding-medium inflation method for frozen section analysis.

Objective: Accurate intraoperative diagnosis of spread through air spaces (STAS), a known poor prognostic factor in lung cancer, is crucial for guiding surgical decision-making during sublobar resections. This study aimed to evaluate the diagnostic sensitivity of STAS using frozen section (FS) slides prepared with the cryo-embedding medium inflation technique. Methods: In this prospective study at Shinshu University Hospital, 99 patients undergoing lung resection for tumors <3 cm in size were included, a total of 114 lesions. FS slides were prepared with injecting diluted cryo-embedding medium into the lung parenchyma of resected specimens. The diagnostic performance of these FS slides for STAS detection was evaluated by comparing FS-STAS results with the gold-standard STAS status. Results: The incidence of STAS, determined by the gold standard, was 43 (38%) of 114 lesions, including 31 (37%) of 84 primary lung cancers and 12 (40%) of 30 metastatic lung tumors. The sensitivity, specificity, positive and negative predictive values, and accuracy of FS slides for STAS detection were 81%, 89%, 81%, 89%, and 86%, respectively. Specifically, in primary lung cancers, these values were 90%, 89%, 82%, 94%, and 89%, respectively. Regarding metastatic lung tumors, the corresponding values were 58%, 89%, 78%, 76%, and 77%, respectively. Conclusions: Our adapted cryo-embedding medium inflation method has demonstrated enhanced sensitivity in detecting STAS on FS slides, providing results similar to the gold-standard STAS detection. Compared with historical benchmarks, this technique could show excellent performance and be readily incorporated into clinical practice without requiring additional resources beyond those used for standard FS analysis.

Stereoinversion via Alcohol Dehydrogenases Enables Complete Catabolism of ß-1-Type Lignin-Derived Aromatic Isomers.

Sphingobium sp. strain SYK-6 is an efficient aromatic catabolic bacterium that can consume all four stereoisomers of 1,2-diguaiacylpropane-1,3-diol (DGPD), which is a ring-opened ß-1-type dimer. Recently, LdpA-mediated catabolism of erythro-DGPD was reported in SYK-6, but the catabolic pathway for threo-DGPD was as yet unknown. Here, we elucidated the catabolism of threo-DGPD, which proceeds through conversion to erythro-DGPD. When threo-DGPD was incubated with SYK-6, the Cα hydroxy groups of threo-DGPD (DGPD I and II) were initially oxidized to produce the Cα carbonyl form (DGPD-keto I and II). This initial oxidation step is catalyzed by Cα-dehydrogenases, which belong to the short-chain dehydrogenase/reductase (SDR) family and are involved in the catabolism of ß-O-4-type dimers. Analysis of seven candidate genes revealed that NAD+-dependent LigD and LigL are mainly involved in the conversion of DGPD I and II, respectively. Next, we found that DGPD-keto I and II were reduced to erythro-DGPD (DGPD III and IV) in the presence of NADPH. Genes involved in this reduction were sought from Cα-dehydrogenase and ldpA-neighboring SDR genes. The gene products of SLG_12690 (ldpC) and SLG_12640 (ldpB) catalyzed the NADPH-dependent conversion of DGPD-keto I to DGPD III and DGPD-keto II to DGPD IV, respectively. Mutational analysis further indicated that ldpC and ldpB are predominantly involved in the reduction of DGPD-keto. Together, these results demonstrate that SYK-6 harbors a comprehensive catabolic enzyme system to utilize all four ß-1-type stereoisomers through successive oxidation and reduction reactions of the Cα hydroxy group of threo-DGPD with a net stereoinversion using multiple dehydrogenases. IMPORTANCE In many catalytic depolymerization processes of lignin polymers, aryl-ether bonds are selectively cleaved, leaving carbon-carbon bonds between aromatic units intact, including dimers and oligomers with ß-1 linkages. Therefore, elucidating the catabolic system of ß-1-type lignin-derived compounds will aid in the establishment of biological funneling of heterologous lignin-derived aromatic compounds to value-added products. Here, we found that threo-DGPD was converted by successive stereoselective oxidation and reduction at the Cα position by multiple alcohol dehydrogenases to erythro-DGPD, which is further catabolized. This system is very similar to that developed to obtain enantiopure alcohols from racemic alcohols by artificially combining two enantiocomplementary alcohol dehydrogenases. The results presented here demonstrate that SYK-6 has evolved to catabolize all four stereoisomers of DGPD by incorporating this stereoinversion system into its native ß-1-type dimer catabolic system.

Multiple deep femoral artery aneurysms with Loeys-Dietz syndrome.

A 60-year-old man with Loeys-Dietz syndrome (LDS) underwent surgery for multiple left deep femoral artery aneurysms (DFAAs). An intraoperative graft replacement was performed from the common femoral artery to the distal DFAAs; the superficial femoral artery was sutured to the graft. DFAAs in association with LDS and the occurrence of multiple DFAAs are rare. To the best of our knowledge, no studies have reported their coexistence. Graft replacement was decided as the optimal treatment for our patient. However, treatment should be considered on a patient-by-patient basis. Therefore, a lower limb arterial examination should accompany the screening of patients with LDS.

Hereditary diffuse gastric cancer in a Japanese family with CDH1 mutation three case reports.

BACKGROUND: Germline pathogenic variants in the E-cadherin gene CDH1 cause hereditary diffuse gastric cancer (HDGC), which is an autosomal dominant cancer syndrome, accounting for 1-3% of all gastric cancers. HDGC harboring a CDH 1 variant is extremely rare in Japan. METHOD: In this study we report the clinical courses of three cases with HDGC from a single Japanese family. RESULTS: The proband exhibited advanced and metastatic gastric cancer, and was found to have a previously reported heterozygous frameshift variant in CDH1 (NM_004360.3:c.1009_1010del:p.Ser337Phefs*12). Five at-risk relatives underwent presymptomatic molecular testing after careful genetic counseling, and three were molecularly diagnosed as positive for the variant. Esophagogastroduodenoscopy was performed in these relatives revealing abnormal small pale mucosal patches, small ulcerative lesion and no abnormal findings. Moreover, random and targeted biopsies were compatible with pathological diagnosis of HDGC in the three cases, all of which underwent total prophylactic gastrectomy. CONCLUSION: It is critical for the assessment and management of HDGC patients to be actively offered a multidisciplinary and familial-oriented approach. Notably, genetic screening in suspected individuals and familial members is a determining piece for a higher detection rate and the identification of clinical relevant mutations in both low and high-incidence gastric cancer countries.

High expression of LGR6 is a poor prognostic factor in esophageal carcinoma.

BACKGROUND: Leucine-rich repeat-containing G-protein-coupled receptor 6 (LGR6) promotes carcinogenesis and progression in some cancer types. However, there are few reports of LGR6 expression in esophageal squamous cell carcinoma (ESCC). LGR6 expression and clinicopathological features in ESCC were investigated by RNAscope, a highly sensitive RNA in situ hybridization method. METHODS: Appropriate tumors were selected from 41 cases of ESCC from which tissue microarrays were generated, and LGR6 expression was identified by RNAscope. RESULTS: Thirty-seven patients had LGR6 expression. High LGR6 expression was observed in 17 cases and low LGR6 expression in 24 cases. LGR6 expression was significantly higher in high histological grade ESCC than in low histological grade ESCC (P = 0.0023). ESCC patients who received neoadjuvant chemotherapy had significantly higher LGR6 expression than those without neoadjuvant chemotherapy (P = 0.0109). Furthermore, high LGR6 expression showed a poorer prognosis than low LGR6 expression (log-rank test, P = 0.0365). CONCLUSIONS: LGR6 may be a prognostic factor and a potential new therapeutic target in ESCC.

Number and distribution of eosinophils and lymphocytes in the Japanese pediatric gastrointestinal tract: in search of a definition for "abnormally increased eosinophils".

BACKGROUND: Primary eosinophilic gastrointestinal disorders (EGIDs) constitute chronic allergic inflammation. The number of eosinophils is one of the diagnostic criteria; more than 20 eosinophils per high-power field (HPF) in the gastrointestinal (GI) tract are considered abnormal in Japan. However, the quantity of eosinophils considered normal varies according to anatomical location and geographical region; such values have not been reported in Japanese pediatric patients, nor have the numbers of lymphocytes in the normal pediatric stomach. To establish a reference for defining diagnostic criteria for EGIDs, we evaluated the number of eosinophils in the normal Japanese pediatric GI tract. METHODS: We examined 131 biopsy cases without significant clinical history, endoscopic abnormality, or histological abnormality. Immunohistochemical analysis of CD3 and CD20 was performed. RESULTS: The mean eosinophil density was highest in the cecum (49.5 ± 22.4 per HPF). Counts of more than 20 eosinophils per HPF were observed in the duodenum [bulb (20.0 ± 9.6) and second portion (30.0 ± 15.8)], terminal ileum (38.3 ± 22.7), cecum (49.5 ± 22.4), ascending colon (42.3 ± 25.3), transverse colon (29.4 ± 17.0), and descending colon (32.2 ± 17.9). Counts of fewer than 10 eosinophils per HPF were observed in the stomach and rectum; a count of fewer than one eosinophil per HPF was observed in the esophagus. More than 100 CD3-positive T cells per HPF were observed in the stomach. CONCLUSIONS: The mean numbers of eosinophils in the bowel were greater than 20 per HPF. For Japanese pediatrics, the current threshold eosinophil count should be revised.

Composite hemangioendothelioma in the cervical spine with kaposiform hemangioendothelioma features in an elderly patient: a case report.

BACKGROUND: Composite hemangioendothelioma (CHE) is an intermediate group of tumors with features between hemangioma and angiosarcoma both histologically and biologically. CHE is predominant in young and middle-aged adults, but very infrequently affects the spine. We describe the case of primary CHE in the cervical spine exhibiting kaposiform hemangioendothelioma (KHE)-like components that was associated with cervical myelopathy with vertebral body destruction in an elderly woman. We retrospectively reviewed the case of a primary cervical spinal tumor, diagnosed as CHE with KHE-like components in pathological findings, associated with cervical myelopathy and cervical vertebral body destruction. CASE PRESENTATION: An 80-year-old woman presented with progressive cervical myelopathy caused by a cervical spine tumor. Preoperative cervical MRI revealed a neoplastic lesion invading the cervical spine that strongly compressed the spinal cord, causing right upper-limb paralysis. We performed partial tumor resection along with posterior decompression and fixation. Postoperatively, pathological findings showed that the tumor was CHE with KHE-like features. Following radiotherapy, no recurrences have been observed in 21 months. CONCLUSIONS: This is the first report of CHE with features of KHE in the spine of an elderly patient. Posterior decompression and fusion of the cervical spine and subsequent radiotherapy resulted in a good outcome.

Correlation of LGR5 expression and clinicopathological features in intrahepatic cholangiocarcinoma.

Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is a known cancer stem cell marker. However, there are no reported analyses of LGR5 mRNA expression in normal liver and liver cancer tissues. Here, we evaluated LGR5 expression by RNAscope, a newly developed RNA in situ hybridization technique, using a tissue microarray consisting of 25 samples of intrahepatic cholangiocarcinoma (ICC) selected from the medical archives at our hospital. LGR5 expression levels were divided into high and low expression groups by the five-grade scoring system, and clinicopathological features were analyzed. Low LGR5 expression was identified in some normal hepatocytes and bile duct cells. In addition, LGR5 expression was identified in all bile duct cancer samples except one case. Well-differentiated to moderately-differentiated adenocarcinoma tended to show higher LGR5 expression than poorly-differentiated adenocarcinoma (P = 0.0561), and the large duct type showed significantly higher LGR5 expression levels than the small duct type (P = 0.0225). Patients in the high LGR5 expression group tended to have good overall survival (OS) (P = 0.0623). The Cox proportional hazard regression model revealed that the high LGR5 expression group showed independently better OS for ICC (P = 0.0285). High LGR5 expression is possibly a good prognosis factor in ICC. However, the detailed mechanism of LGR5 in this disease remains unclear, and further analysis is warranted.

LGR5 expression and clinicopathological features of the invasive front in the fat infiltration area of pancreatic cancer.

BACKGROUND: Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is a strong cancer stem cell marker in colorectal cancer; however, there are many unclear aspects of LGR5 expression in pancreatic cancer. It has been reported that the interaction between tumor cells and stroma at the fat infiltration site has a significant effect on pancreatic cancer prognosis. Therefore, we report a clinicopathological study of LGR5 expression at the fat invasion front in pancreatic cancer. METHODS: LGR5 expression was analyzed in 40 pancreatic ductal adenocarcinoma cases with RNAscope, which is a newly developed high-sensitivity in situ hybridization method. Epithelial-mesenchymal transition (EMT) was analyzed by the expression of E-cadherin and vimentin via immunohistochemistry. RESULTS: LGR5-positive dots were identified in all cases, especially with glandular formation. In the fat invasion front, a high histological grade showed significantly reduced LGR5 expression compared with a low histological grade (p=0.0126). LGR5 expression was significantly higher in the non-EMT phenotype group than in EMT phenotype group (p=0.0003). Additionally, LGR5 expression was significantly lower in cases with high vascular invasion than in those with low vascular invasion (p=0.0244). CONCLUSIONS: These findings suggest that decreased LGR5 expression in the fat invasion front is associated with more aggressive biological behavior in pancreatic ductal adenocarcinoma, with higher tumor grade, EMT phenotype, and higher vascular invasion.

Concordance of the histological diagnosis of type 1 autoimmune pancreatitis and its distinction from pancreatic ductal adenocarcinoma with endoscopic ultrasound-guided fine needle biopsy specimens: an interobserver agreement study.

The histological diagnosis of type 1 autoimmune pancreatitis (AIP) based on the findings obtained by an endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) is feasible, but the diagnostic consistency of this method has not been confirmed. We determined the interobserver agreement among 20 pathologists regarding the diagnosis of type 1 AIP, including the distinction from pancreatic ductal adenocarcinoma (PDAC) using large tissue samples obtained by EUS-FNB. After guidance for diagnosing AIP with biopsy tissues was provided, a round 2 was performed. The median sensitivity and specificity for diagnosing PDAC vs. non-neoplastic diseases were 95.2% and 100%, respectively. In groups of specialists (n = 7) and the generalists (n = 13), Fleiss' к-values increased from 0.886 to 0.958 and from 0.750 to 0.816 in round 2. The concordance was fair or moderate for obliterative phlebitis and storiform fibrosis but slight for ductal lesion of type 1 AIP. Discordant results were due to ambiguous findings and biopsy tissue limitations. Among the specialists, the ratio of cases with perfect agreement regarding the presence of storiform fibrosis increased in round 2, but agreement regarding obliterative phlebitis or ductal lesions was not improved. Although the histological definite diagnosis of type 1 AIP was achieved by most observers in > 60% of the cases, the confidence levels varied. Because some ambiguities exist, the histological diagnostic levels based on the diagnostic criteria of type 1 AIP should not be taken for granted. Guidance is effective for improving accurate PDAC diagnoses (notably by recognizing acinar-ductal metaplasia) and for evaluating storiform fibrosis.

IL-6 expression helps distinguish Castleman's disease from IgG4-related disease in the lung.

BACKGROUND: It is difficult to distinguish between multicentric Castleman's disease (MCD) and IgG4-related lung disease (IgG4-LD), an IgG4-related disease (IgG4-RD) in the lung. METHODS: We focused on IL-6, which is elevated in MCD, to distinguish between MCD and IgG4-LD by RNAscope, a highly sensitive RNA in situ method. Six cases of MCD and four cases of IgG4-LD were selected. RESULTS: In all cases of MCD and IgG4-LD, 10 or more IgG4-positive cells were found in one high-power field. All MCD cases were inconsistent with the pathological IgG4-related comprehensive diagnostic criteria, but 2 of 6 cases had an IgG4/IgG ratio greater than 40%. In all IgG4-LD cases, histological features were consistent with the pathological IgG4-RD comprehensive diagnostic criteria. IL-6 expression was observed in all MCD and IgG4-LD cases except for one IgG4-LD biopsy. IL-6-expressing cells were mainly identified in the stroma. Sites of IL-6 expression were not characteristic and were sparse. IL-6 expression tended to be higher in MCD compared with IgG4-LD. A positive correlation was found between the IL-6 H-score and serum IL-6 level. CONCLUSION: Differences in IL-6 expression may help distinguish between MCD and IgG4-LD. In addition, the presence of high IL-6 levels may help elucidate the pathological mechanisms of IgG4-LD.

Thymic epithelial tumor with superior vena cava syndrome diagnosed by percutaneous endovascular tumor biopsy: A report of two cases.

Thymic epithelial tumor is a rare, potentially progressive disease that commonly infiltrates mediastinal structures. In rare cases, it may cause superior vena cava syndrome. Pretreatment histopathological diagnosis is essential to determine the most effective treatment strategy. Percutaneous endovascular biopsy is a rarely reported non-surgical diagnostic option for large vessel tumoral involvement. We report two cases of thymic epithelial tumor with superior vena cava syndrome diagnosed by percutaneous endovascular biopsy. No procedural complications occurred, and subsequent systemic treatment was promptly administered. This procedure may have potential as a useful diagnostic method for patients with mediastinal tumors involving large vessels.

LGR5 expression is associated with prognosis in poorly differentiated gastric adenocarcinoma.

BACKGROUND: Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is an important cancer stem cell marker in gastric cancer. However, no detailed studies are available on LGR5 expression in poorly differentiated gastric adenocarcinoma (PD-AC). Therefore, we investigated the relationship between LGR5 expression and clinicopathological data in PD-AC. METHODS: LGR5 mRNA expression levels were quantified in 41 PD-AC specimens using a highly sensitive RNAscope in situ hybridization technique. Epstein-Barr virus (EBV) infection was also detected by EBV in situ hybridization. RESULTS: LGR5 expression levels were measured in 38 of 41 PD-AC cases, and 17 cases were identified as LGR5 high. The frequency of EBV positivity tended to be higher in the LGR5-low group than in the LGR5-high group (P = 0.0764). Furthermore, the frequency of vascular invasion tended to be higher in the LGR5-high group than in the LGR5-low group (P = 0.0764). The overall survival of PD-AC patients in the LGR5-high group was significantly lower than in the LGR5-low group (log-rank test, P = 0.0108). The Cox proportional hazard regression model revealed that the LGR5-low group (HR = 0.29; 95% CI: 0.11-0.74; P = 0.01) showed independently better OS for PD-AC. CONCLUSIONS: Quantifying the levels of LGR5 expression may facilitate defining prognosis in Japanese patients with PD-AC. Further study of LGR5 in this context is warranted.

Magnetization Characteristics of Oriented Single-Crystalline NiFe-Cu Nanocubes Precipitated in a Cu-Rich Matrix.

In this study, we evaluated the magnetization properties of a magnetic alloy with single-crystalline cubic nanostructures, in order to clarify its magnetocrystalline anisotropy. Upon applying a specific annealing treatment to the CuNiFe base material, the precipitated magnetic particles grew into cubic granules, resulting in the formation of nanometric cubic single crystals of magnetic CuNiFe in a nonmagnetic Cu-rich matrix. The cubic nanostructures of CuNiFe were oriented along their crystallographic axis, in the <100> direction of the face-centered-cubic structure. We evaluated the static magnetization properties of the sample, which originated primarily from the CuNiFe nanocubes precipitated in the Cu-rich matrix, under an applied DC magnetic field. The magnetocrystalline anisotropy was readily observed in the magnetization curves. The <111> axis of the CuNiFe was observed to be the easy axis of magnetization. We also investigated the dynamic magnetization properties of the sample under an AC magnetic field. By subtracting the magnetic signal induced by the eddy current from the magnetization curves of the sample, we could obtain the intrinsic AC magnetization properties of the CuNiFe nanocubes.

Immunostaining With Immunoglobulin G Subclass Antibody Cocktail for Diagnosis of Type 1 Autoimmune Pancreatitis.

BACKGROUND.: Immunoglobulin (Ig) G4-related diseases (RDs) are systemic diseases in which serum IgG4 levels are frequently elevated. They can cause diffuse or focal tumor formation, organ swelling, and tissue thickening in organs infiltrated by IgG4+ plasma cells. The diagnostic criteria for IgG4-RDs include an IgG4/IgG ratio >40%, but counting IgG+ cells can be difficult because of the weakness of IgG staining density. We hypothesized that an antibody cocktail of mixed IgG1, IgG2, IgG3, and IgG4 (AC-IgG) might give immunohistochemistry results comparable with those of IgG in IgG4-RD. METHODS.: We compared AC-IgG reactivity with IgG expression in type 1 autoimmune pancreatitis (AIP), a representative IgG4-RD. We compared immunohistochemistry results using AC-IgG and IgG-only in 10 cases of AIP. The coefficient of variation (Cv) was used to analyze differences between AC-IgG and IgG findings in AIP by 13 board-certified pathologists. RESULTS.: Although mean values for IgG+ cells did not significantly differ between AC-IgG (34.3; range = 27.4-37.1) and IgG (30.0; range = 23.0-45.6; P = .6254), Cv was lower for AC-IgG (33.4%) than for IgG (51.4%; regression equation; y[IgG] = 0.988x + 0.982; correlation coefficient = 0.907). The data showed that the results of both methods were largely consistent. CONCLUSION.: AC-IgG could replace IgG to count IgG+ cells because of its lower Cv.

An autopsy case of widespread brain dissemination of glioblastoma unnoticed by magnetic resonance imaging after treatment with bevacizumab.

BACKGROUND: Although glioblastoma has been shown to be able to disseminate widely in the intracranially after treatment with bevacizumab without any significant radiological findings, reports on such cases with subsequent autopsy findings are lacking. CASE DESCRIPTION: A 36-year-old man presented with a general seizure and a mass of the right frontal lobe, which was diagnosed as diffuse astrocytoma (WHO Grade II). The patient underwent a total of four surgeries from 2005 to 2017. He showed tumor recurrence, progression, and malignant transformation to glioblastoma (GBM) (WHO Grade IV) despite repeated tumor resections, radiotherapy, and chemotherapies with temozolomide and carmustine wafers. Bevacizumab (10 mg/kg body weight) was started following the fourth surgery. After bevacizumab administration, the patient's clinical condition improved to a Karnofsky performance status (KPS) score of 50-60, and he was stable for several months before finally deteriorating and passing away. Although sequential magnetic resonance imaging (MRI) showed shrinkage of the lesion and a reduction of edema, an autopsy showed widespread tumor invasion that was not revealed on MRI. Neoplastic foci were identified extensively in the cerebral cortex, basal ganglia, pituitary gland, cerebellum, and brainstem, imposing as gliomatosis cerebri. CONCLUSION: Imaging follow-up of malignant gliomas needs to be interpreted with caution as marked improvement in radiological response after bevacizumab treatment may not be indicating tumor regression. Despite the notable lack of evidence to increase overall survival in GBM patients with bevacizumab, the increase in progression-free survival and the observed relief of symptoms due to a decrease in edema should be considered relevant for patient management.

Effect of Equol on Vasocontractions in Rat Carotid Arteries Treated with High Insulin.

Previous research has indicated that high insulin affects vascular function. Equol is an active metabolite of daidzein, an isoflavone produced from soy by intestinal microbial flora, with beneficial effects on the vascular system. This study investigated whether equol was beneficial for vascular function under high insulin conditions. Using organ culture techniques, rat carotid arteries were treated for 23 ± 1 h with a vehicle, high insulin (100 nM), or equol (100 µM) plus high insulin (100 nM). Vascular isometric forces were measured by the organ bath technique. In each endothelium-intact ring, the contractions induced by high-K+, noradrenaline, or by serotonin (5-HT) were similar for the vehicle, insulin, and equol + insulin treatments. Contractions induced by a selective 5-HT2A receptor agonist (TCB2) increased with insulin treatment (vs. vehicle), but less so with equol + insulin. Under basal conditions, a selective 5-HT2B receptor agonist (BW723C86) did not induce contraction; following precontraction by a thromboxane analog, it induced contraction but not relaxation. These responses were similar across the three treatments. Acetylcholine-induced relaxations were also similar for the three treatments. In the endothelium-denuded preparations, 5-HT-induced contraction was augmented with insulin treatment (vs. vehicle) but less so by equol + insulin treatment. These differences in 5-HT-induced contractions were eliminated by iberiotoxin, a large-conductance calcium-activated K+ channel (BKCa) inhibitor. These results suggest that equol exerts a preventive effect on the enhancement of 5-HT-induced contraction by high insulin (possibly mediated by the 5-HT2A receptor), and that these effects may be attributed to the activation of BKCa channels in vascular smooth muscle.

Impairment of Protease-Activated Receptor 2-Induced Relaxation of Aortas of Aged Spontaneously Hypertensive Rat.

Hypertension is one of the most prevalent diseases worldwide and can cause harmful complications within the vascular system. Further research on vascular responsiveness to different ligands and diverse receptors in various arteries is required to understand the mechanisms underlying the development of these vascular complications. Here, we investigated the vasorelaxant effect of the protease-activated receptor 2 (PAR2) agonist 2-furoyl-LIGRLO-amide (2-Fly) and two commonest agents, namely endothelium-dependent dilator acetylcholine (ACh) and endothelium-independent dilator sodium nitroprusside (SNP), on the thoracic aorta isolated from aged spontaneously hypertensive rats (SHR) (age, 52±1 weeks). The effects of these agents were compared between aortas isolated from SHR and age-matched normotensive Wistar Kyoto (WKY) rats. Compared with the WKY group, in the SHR group, 2-Fly-induced relaxation was impaired, ACh-induced relaxation was slightly decreased at low concentrations, and SNP-induced relaxation was similar. In addition, 2-Fly-induced aortic relaxation was largely decreased by a PAR2 antagonist (FSLLRY), endothelial denudation, and a nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine (L-NNA) but not by an Akt inhibitor. These results suggested that PAR2-induced relaxations of aortas of aged SHR was impaired, and this impaired aortic relaxation may be attributed to decreased NO bioavailability rather than altered NO sensitivity unrelated to the Akt activity.

Differential participation of calcium-activated potassium channel in endothelium-dependent hyperpolarization-type relaxation in superior mesenteric arteries of spontaneously hypertensive rats.

The purpose of this study was to determine the relationship of KCa channels to endothelium-dependent hyperpolarizing factor (EDHF)-mediated relaxation induced by acetylcholine (ACh) in the superior mesenteric arteries of 7-month-old spontaneously hypertensive rats (SHR). Upon inhibition of nitric oxide synthase and cyclooxygenase, ACh-induced EDHF-mediated relaxation was found to be weaker in SHR than in age-matched Wistar Kyoto rats (WKY). These relaxations in both group were attenuated by combined treatment with small-conductance and intermediate-conductance Ca2+-activated K+ channels (SKCa and IKCa) inhibitors, with the exception of relaxation resistant to inhibition of these channels in SHR (vs. WKY). Treatment with large-conductance Ca2+-activated K+ channels (BKCa) inhibitor specifically attenuated relaxation in SHR, but not in WKY. Protein expression of IKCa and SKCa in the arteries did not differ between the 2 groups, whereas ratio of sloß1 subunit to α subunit of BKCa was increased in SHR (vs. WKY). These results suggest that EDHF-mediated relaxations in superior mesenteric arteries are impaired in SHR, and utilize components of BKCa in addition to SKCa/IKCa channel activities, that the increased participation of BKCa may be attributable to alterations in α and sloß1 subunit ratio, and that components unrelated to KCa activity may also contribute to the difference between SHR and WKY arteries.

UDP-induced relaxation is enhanced in aorta from female obese Otsuka Long-Evans Tokushima Fatty rats.

Uridine 5'-diphosphate (UDP) plays an important role in controlling vascular tone; however, UDP-mediated response in metabolic syndromes, including obesity and type 2 diabetes in females, remains unclear. In this study, we investigated UDP-mediated response in the aorta of female obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats and control Long-Evans Tokushima Otsuka (LETO) rats. In OLETF rat aortas precontracted by phenylephrine (PE) (vs. LETO), (1) UDP-induced relaxation was increased, whereas acetylcholine (ACh)-induced relaxation was decreased; (2) no UDP- or ACh-induced relaxations were observed in endothelial denudation, whereas UDP-induced small contraction was observed; and (3) NG-nitro-L-arginine [L-NNA, a nitric oxide (NO) synthase inhibitor] eliminated UDP-induced relaxation and small contraction, whereas caused contrasting responses by ACh, including slight relaxations (LETO) and contractions (OLETF). Indomethacin, a cyclooxygenase inhibitor, eliminated the difference in UDP- and ACh-induced relaxations between the groups by increased UDP-induced relaxation in the LETO group and increased ACh-induced relaxation in the OLETF group. MRS2578, a P2Y6 receptor antagonist, eliminated the difference in UDP-induced relaxations between the groups by decreasing UDP-induced relaxation in the OLETF group. MRS2578 had no effect on UDP-induced contraction in endothelium-denuded aortas. Therefore, these findings demonstrate opposite trends of relaxations by UDP and ACh in OLETF and LETO rat aortas. These differences may be attributed to the imbalance between NO and vasoconstrictor prostanoids upon stimulations. Increased UDP-induced relaxation in OLETF rat aorta may be caused by the activation of endothelial MRS2578-sensitive P2Y6 receptor.