RhoA G17E/Vav1 Signaling Induces Cancer Invasion via Matrix Metalloproteinase-9 in Gastric Cancer

BACKGROUND

RAS homolog family member A (RhoA), a member of the Rho family of small GTPases, and Vav1, a guanine nucleotide exchange factor for Rho family GTPases, have been reported to activate pathways related to the actin cytoskeleton and regulation of cell shape, attachment, and motility. The interaction between these molecules in lymphoma is involved in malignant signaling, but its function in epithelial malignancy is unknown. Here, we investigated the malignant signal of mutant RhoA in gastric cancer and demonstrated the potential of RhoA G17E/Vav1 as a therapeutic target for diffuse gastric cancer.

METHODS

The RhoA mutants R5W, G17E, and Y42C were retrovirally transduced into the gastric cancer cell line MKN74. The stably transduced cells were used for morphology, proliferation, and migration/invasion assays in vitro. MKN74 cells stably transduced with ectopic wild-type RhoA and mutant RhoA (G17E) were used in a peritoneal xenograft assay.

RESULTS

The RhoA mutations G17E and Y42C induced morphological changes in MKN74. G17E induced Vav1 expression at the mRNA and protein levels and promoted the migration and invasion of MKN74. An RNA interference assay of Vav1 revealed that RhoA G17E enhanced cancer cell invasion via Vav1. Furthermore, immunoprecipitation revealed that Vav1 and RhoA G17E specifically bind and function together through matrix metalloproteinase -9. In a peritoneal xenograft model of nude mice, RhoA G17E promoted peritoneal dissemination, whereas Vav1 knockdown suppressed it.

CONCLUSION

Overall, our findings indicate that RhoA G17E is associated with Vav1 and promoted cancer invasion via matrix metalloproteinase -9 in gastric cancer cells. Thus, RhoA G17E/Vav1 signaling in diffuse gastric cancer may be a useful therapeutic target.

Gastric glomus tumor resection using laparoscopic endoscopic cooperative surgery: A case report

Gastric glomus tumors are rare submucosal mesenchymal neoplasms that are difficult to diagnose preoperatively. We present a case of a 60-year-old woman who was diagnosed with a gastric glomus tumor using endoscopic ultrasonography-guided fine-needle aspiration biopsy. The tumor was successfully resected with laparoscopic endoscopic cooperative surgery (LECS). LECS could be an effective method for the resection of gastric glomus tumors.

Risk factors for umbilical incisional hernia after laparoscopic colorectal surgery

BACKGROUND

Laparoscopic colorectal surgery (LCRS) requires a small laparotomy at the umbilicus. The wound is small and inconspicuous, but if the patient develops an umbilical incisional hernia (UIH), the wound is visible and the patient suffers from symptoms of discomfort. However, the incidence of UIH after LCRS and its risk factors are not well understood. The purpose of this study was to investigate the risk factors for UIH after LCRS for colorectal cancer.

METHODS

This was a single-centre retrospective study of 135 patients with colorectal cancer, conducted at our hospital from April 2013 to March 2019. The diagnosis of UIH was based on computed tomography and physical examination findings. Preoperative patient data such as enlargement of the umbilical orifice (EUO), subcutaneous fat thickness (SFT) and intraperitoneal thickness (IPT) were collected and analysed using univariate and multivariate analyses for the presence of risk factors for UIH.

RESULTS

A total of 135 patients who underwent LCRS were analysed. The incidence of UIH was 20.7%. Univariate analysis revealed significantly high body mass index (BMI) ≥ 25 (P = 0.032), EUO (P < 0.001), SFT ≥18 mm (P = 0.011), and IPT ≥61 mm (P < 0.01) in the UIH group. Multivariate analysis revealed significant differences in EUO (P < 0.001), SFT ≥18 mm (P = 0.046) and IPT ≥61 mm (P = 0.022).

CONCLUSION

EUO was the most important risk factor for UIH, followed by IPT and SFT. These findings are predictive indicators of the development of UIH after LCRS and can be assessed objectively and easily with preoperative computed tomography.

Osteopontin expression in the invasive front stroma of colorectal adenocarcinoma is associated with tumor budding and prognosis

BACKGROUND

Tumor budding (TB) is an important prognostic factor in colorectal carcinoma (CRC). Osteopontin (OPN) functions in various processes such as immune response, migration and invasion, angiogenesis, epithelial-mesenchymal transition (EMT) and metastasis. However, the involvement of OPN and CD44v6, which is a receptor for OPN, in TB has not been clarified. Therefore, we examined the relationship of OPN with TB in CRC and compared the clinicopathological features.

METHODS

We investigated the expression of OPN and CD44v6 in 83 cases of CRC by immunostaining and analyzed the clinicopathological features.

RESULTS

OPN expression was observed mostly in the cytoplasm of stromal cells such as macrophages and fibroblasts, and rarely in cancer cells. There was a significant correlation between OPN positivity and the degree of differentiation at the invasive front and TB grade. CD44v6 was positive in cancer cells in 72 cases (86.7 %) and negative in 11 cases (13.3 %). A statistically significant effect on overall survival (OS) was identified between the OPN-positive group [median OS: 1586 (range, 30-2749) days] and the OPN-negative group [median OS: 1901 (range, 8-2665) days] (log-rank test, p = 0.011).

CONCLUSIONS

OPN analysis in CRC stromal cells may have prognostic implications.

Comparison of Clinical Outcomes and Safety Between Open and Laparoscopic Surgery for Adhesive Small Bowel Obstruction: A Propensity-Matched Analysis of a National Inpatient Database

Background: The effectiveness of laparoscopic surgery for adhesive small bowel obstruction (ASBO) remains unclear. We aimed to compare the outcomes and safety of open and laparoscopic surgeries for ASBO. Methods: In this retrospective study, we analyzed an inpatient database of 42 national university hospitals in Japan. Patients who underwent surgery for the first episode of ASBO between April 2013 and March 2018 were identified. Using the propensity score method, patients who underwent laparoscopic surgery were matched one-to-one with those who underwent open surgery. We investigated postoperative clinical outcomes, including morbidity, mortality, length of hospital stay (LOS), and recurrence. Results: Overall, 306 and 96 patients underwent open and laparoscopic surgery, respectively (96 propensity score-matched pairs). The incidence rates of postoperative morbidity, mortality, and recurrence were comparable between the two groups. Cox regression analysis revealed a hazard ratio (HR) of 1.020 (P = .959) for readmission due to ASBO in the laparoscopic surgery group relative to the open surgery group. Postoperative hospital stay was longer for open surgery than for laparoscopic surgery (13.0 days versus 10.0 days, P < .001). Cox regression analysis revealed that laparoscopic surgery was associated with earlier postoperative discharge compared with open surgery (HR 1.641, P = .002). Conclusions: The postoperative LOS was shorter with laparoscopic surgery than with open surgery for ASBO, but there were no differences between the procedures in other clinical outcomes. Laparoscopic surgery is suitable to treat patients with ASBO.

Association of Daily Variance in Air Temperature With Postoperative Adhesive Small Bowel Obstruction

Introduction: The influence of air temperature on adhesive small bowel obstruction (ASBO) is unknown. This study aimed to investigate the relationship between air temperature and postoperative ASBO.

Methods: Overall, 312 patients with postoperative ASBO were included. They were categorized into two groups: the surgery group (n = 83) comprising patients who needed surgery, and the non-surgery group (n = 229) comprising patients who responded to conservative treatment. The associations between patients’ characteristics and weather variables on days of symptom onset with the need for surgical management were investigated. Weather variables included the daily mean barometric pressure, daily mean air temperature, day-to-day differences, daily variances, and diurnal variation in the air temperature. Day-to-day differences in weather variables were calculated as the daily mean variables on the day of symptom onset minus those on the previous day. The daily variances in weather variables were defined as the absolute value of day-to-day differences.

Results: Compared to the non-surgery group, the surgery group had older patients (75 vs. 70 years, p = 0.009), a higher proportion of female patients (44.6% vs. 32.3%, p = 0.046), increased incidence of closed-loop sign (50.6% vs. 0.9%, p < 0.001), a lower proportion of feces sign (18.1% vs. 31.3%, p = 0.024), and a prolonged hospital stay (11 vs. 22 days, p < 0.001). The number distribution of patients in the surgery group in day-to-day differences in air temperature was different from that of the non-surgery group; the former has several peaks whereas the latter has almost one peak. Daily variance in mean air temperature on the day of symptom onset was higher in the surgery group than in the non-surgery group (2.3 vs. 1.3℃, p < 0.001). Multiple logistic regression analysis revealed that increased daily variance in air temperature on the onset day was associated with the need for surgical management (odds ratio 1.254, p = 0.002) and closed-loop obstruction (odds ratio 1.235, p = 0.017). Regarding seasonal variations, the risk of the need for surgery and closed-loop obstruction in each ASBO patient was the highest in spring, followed by that in summer, autumn, and winter. Consistently, the daily variance in mean air temperature in spring was higher than that in summer, autumn, and winter (p < 0.0001, p < 0.0001, and p = 0.0047, respectively). The risk of the need for surgery and closed-loop obstruction in each ASBO patient was the highest in spring, followed by that in summer, autumn, and winter. Consistently, daily variance in mean air temperature was higher in spring than that in summer, autumn, and winter (p < 0.0001, p < 0.0001, and p = 0.0047, respectively).

Conclusion: Increased daily variance in mean air temperature on the day of onset is associated with the need for surgical management and closed-loop obstruction. Spring is characterized by the highest daily variance in mean air temperature among the four seasons, and is associated with high proportions of the need for surgery and closed-loop obstruction. These results can be clinically useful in terms of hospital resource reallocation and staffing, and can help clarify the pathogenesis of ASBO.

Impact of seasonal and meteorological factors on the incidence of adhesive small bowel obstruction: A large‐scale study using a national inpatient database

Aim

Whether seasonal and meteorological factors affect the incidence of adhesive small bowel obstruction (ASBO) remains unclear. This study aimed to clarify the impacts of seasonal and meteorological factors on the occurrence of ASBO.

Methods

Clinical data of patients with ASBO were acquired from 42 national university hospitals in Japan, using a national inpatient database, between April 2012 and March 2020. Meteorological data were obtained from the Japan Meteorological Agency. The number of monthly admissions of patients with ASBO was compared between each of the 12 months. Daily weather variables were investigated to clarify their association with ASBO patient admissions on a total of 119 802 days (Formula for calculation: study period [2922 days] ×41 cities).

Results

Overall, 4985 patients with ASBO were admitted. The number of admissions in June was smaller than that in October, November, and December (39 vs 63.5, P = .002, 39 vs 65, P = .004, and 39 vs 59.5, P = .002, respectively). Logistic regression analysis revealed that January, October, November, and December were associated with increased risk of admission compared to June (odds ratio [OR], 1.264; P = .001; OR, 1.454; P < .001; OR, 1.408; P < .001; OR, 1.330; P < .001), respectively. Regarding the weather variables, higher barometric pressure and lower humidity were associated with increased risk of admission (OR, 1.011; P < .001 and OR, 0.995; P < .001), respectively.

Conclusion

The incidence of ASBO is susceptible to barometric pressure and humidity and varies monthly. These results can contribute to the prevention, early detection, and immediate and appropriate management of ASBO.

A case of appendiceal ganglioneuroma in neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 is an autosomal dominant inherited disease associated with multiple skin neurofibromas or other neurogenic tumors, such as nodular plexiform neurinoma or cerebrospinal tumor. Gastrointestinal stromal tumors are often complicated in patients with neurofibromatosis type 1, although involvement of the appendix is rare, and there have been few reports of appendiceal ganglioneuroma.

CASE PRESENTATION

The patient was a 29-year-old man diagnosed with neurofibromatosis type 1 based on physical findings and his family history. During the follow-up of neurofibromatosis, computed tomography was performed to detect neurological tumors, such as neurofibromas in the brain, spinal cord, and gastrointestinal tract. Computed tomography showed a markedly thickened appendix wall, and an appendiceal tumor was suspected. Laparoscopic appendectomy was performed, and a 50 × 35 mm appendiceal submucosal tumor was resected with a negative resection margin. At histopathological examination, the tumor was diagnosed as ganglioneuroma; it showed short spindle-shaped cells and ganglion cells diffusely infiltrated into the proper muscle layer and fibrous tissue that grew around nerve cells. The patient was discharged on the 5th postoperative day without postoperative complications and was doing well at 13 months following the operation.

CONCLUSIONS

Gastrointestinal stromal tumor and neurofibroma are the most common gastrointestinal tumors associated with neurofibromatosis type 1, but ganglioneuroma of the appendix is rare. Appendiceal neurogenic tumors should be considered in patients with neurofibromatosis type 1, and surgical resection is necessary because of the risk of malignancy.

Lymphocyte-to-Monocyte Ratio Is a Predictive Biomarker of Response to Treatment with Nivolumab for Gastric Cancer

INTRODUCTION

Patients with unresectable or recurrent gastric cancer who have an objective response (OR) to nivolumab monotherapy are expected to have a good long-term prognosis. However, the OR rate for nivolumab treatment is low at 11%, and there is a need for biomarkers to predict the treatment response. This study aimed to analyze the significance of systemic inflammation-related variables and clinicopathologic characteristics as predictive markers of response to nivolumab monotherapy in patients with advanced gastric cancer.

METHODS

In this retrospective cohort study, we enrolled 71 consecutive patients who received nivolumab monotherapy for unresectable or recurrent gastric cancer. Receiver operating characteristic curve analysis was performed to determine the cutoff values of systemic inflammation-related variables, predictors of treatment response, and other prognostic factors related to nivolumab therapy. We focused on systemic inflammation-related variables measured before nivolumab induction and 2 weeks after its first administration and performed multivariate analysis to assess whether they could be used as prognostic factors.

RESULTS

Multivariate analysis revealed that a lymphocyte-to-monocyte ratio (LMR) of ≤3.28 after 2 weeks of initial nivolumab treatment (2wLMR) is a statistically significant predictor of treatment response (p = 0.012). The progression-free survival (PFS) rate of patients with liver metastasis was significantly worse than that of the other patients (1-year PFS: 0.0 vs. 24.4%, respectively; p = 0.005). The overall survival (OS) of patients with a low 2wLMR was significantly longer than that in patients with a high 2wLMR (1-year OS: 37.4 vs. 18.9%, respectively; p = 0.022).

CONCLUSIONS

Thus, the 2wLMR could be a useful biomarker to predict response to nivolumab treatment and the prognosis of unresectable and recurrent gastric cancer.

Drug sensitivity profile of minor KRAS mutations in colorectal cancer using mix culture assay: The effect of AMG-510, a novel KRAS G12C selective inhibitor, on colon cancer cells is markedly enhanced by the combined inhibition of MEK and BCL-XL

Colorectal cancer with a Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) gene mutation is considered to be resistant to anti-EGFR agents. G12D is the most common KRAS mutation in colorectal cancer, followed by G12V and G13D. According to clinical and basic research data, patients with colorectal cancer exhibiting G12D and G12V KRAS mutations are resistant to anti-EGFR agents; however, this is not true of G13D and other minor mutations, which are still not well understood. The current study focused on minor KRAS mutations (G12A, G12C, G12S, Q61H and A146T) and evaluated whether these were resistant to anti-EGFR antibodies using a mix culture assay. The results demonstrated that all KRAS mutations, including minor mutations, were resistant to two anti-EGFR agents: Cetuximab and panitumumab. The combined effect of MEK and BCL-XL inhibition on colorectal cancer cells with KRAS minor mutations were subsequently evaluated. The combined effect of MEK and BCL-XL inhibitors was confirmed in all KRAS minor mutations. The sensitivity of AMG510, a novel KRAS G12C selective inhibitor, was also assessed. The mix culture assay revealed that AMG510 selectively exerted an antitumor effect on colon cancer cells with a G12C KRAS mutation. The combination of MEK and BCL-XL inhibition markedly enhanced the effect of AMG510 in colon cancer cells. The current study suggested that AMG510 may have potential clinical use in combination with MEK and BCL-XL inhibitors in the treatment of patients with colorectal cancer exhibiting the G12C KRAS mutation.

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.

Low‑dose trametinib and Bcl‑xL antagonist have a specific antitumor effect in KRAS‑mutated colorectal cancer cells

KRAS‑mutant colorectal cancer (CRC) is a highly malignant cancer with a poor prognosis, however specific therapies targeting KRAS mutations do not yet exist. Anti‑epidermal growth factor receptor (EGFR) agents, including cetuximab and panitumumab, are effective for the treatment of certain patients with CRC. However, these anti‑EGFR treatments have no effect on KRAS‑mutant CRC. Therefore, new therapeutic strategies targeting KRAS‑mutant CRC are urgently needed. To clarify the direct effect of KRAS gene mutations, the present study transduced mutant forms of the KRAS gene (G12D, G12V and G13D) into CACO‑2 cells. A drug‑screening system (Mix Culture assay) was then applied, revealing that the cells were most sensitive to the MEK inhibitor trametinib among tested drugs, Cetuximab, Panitumumab, Regorafenib, Vemurafenib, BEZ‑235 and Palbociclib. Trametinib suppressed phosphorylated ERK (p‑ERK) expression and inhibited the proliferation of KRAS‑mutant CACO‑2 cells. However, low‑dose treatment with trametinib also increased the expression of the anti‑apoptotic protein Bcl‑xL in a dose‑dependent manner, leading to drug resistance. To overcome the resistance of KRAS‑mutant CRC to apoptosis, the combination of trametinib and the Bcl‑xL antagonist ABT263 was assessed by in vitro and in vivo experiments. Compared with the effects of low‑dose trametinib monotherapy, combination treatment with ABT263 had a synergistic effect on apoptosis in mutant KRAS transductants in vitro. Furthermore, in vivo combination therapy using low‑dose trametinib and ABT263 against a KRAS‑mutant (G12V) xenograft synergistically suppressed growth, with an increase in apoptosis compared with the effects of trametinib monotherapy. These data suggest that a low dose of trametinib (10 nM), rather than the usual dose of 100 nM, in combination with ABT263 can overcome the resistance to apoptosis induced by Bcl‑xL expression, which occurs concurrently with p‑ERK suppression in KRAS‑mutant cells. This strategy may represent a promising new approach for treating KRAS‑mutant CRC.

Treatment of Rectal Cancer-Induced Disseminated Carcinomatosis of the Bone Marrow with FOLFOX plus Cetuximab and Panitumumab

Disseminated carcinomatosis of the bone marrow (DCBM) in colorectal cancer is an extremely rare complication with a poor prognosis. Here, we report a case of DCBM due to rectal cancer successfully treated with a combination of FOLFOX and an anti-epidermal growth factor receptor (EGFR) agent. The patient was a 38-year-old man diagnosed with rectal cancer with multiple bone and para-aortic lymph node metastases complicated by disseminated intravascular coagulation (DIC). He first recovered from DIC following cotreatment with FOLOX plus cetuximab; subsequently, the second attack was successfully treated with FOLFOX plus panitumumab. His initial condition was extremely poor, but he survived with two FOLFOX plus anti-EGFR regimens and died 333 days after introduction of chemotherapy.

High incidence of other primary malignancies in patients with synchronous multiple gastric cancers "a multi-center retrospective cohort study"

This study evaluated the relationship between synchronous multiple gastric cancer and other primary malignancies. During 2002–2013, 1094 consecutive surgically treated gastric cancer patients were enrolled. Preoperatively, we performed total colonoscopy and whole-body computed tomography. When malignancies in other organs were suspected, detailed organ-specific examinations were performed. Synchronous multiple gastric cancer occurred in 102 patients (9.3%)which was frequently observed in patients with preoperative other primary malignancies (p < 0.001). Preoperative other primary malignancy was an independent risk factor for synchronous multiple gastric cancer (p = 0.001; hazard ratio: 2.145, 95% confidence interval: 1.354–3.399) and an independent prognostic factor of overall survival in patients undergoing gastrectomy with curative intent (p = 0.021; hazard ratio: 1.481, 95% confidence interval: 1.060–2.070). Thus, patients with preoperative other primary malignancies have a high risk of synchronous multiple gastric cancer. Careful preoperative examination is recommended to improve survival.

Three Cases of Pseudo-Meigs' Syndrome Secondary to Ovarian Metastases from Colorectal Cancer

Pseudo-Meigs' syndrome is used to describe cases of ascites and/or pleural effusion associated with ovarian neoplasms other than benign tumors, which improve after removal of the ovarian lesion. We present three cases of pseudo-Meigs' syndrome secondary to ovarian metastasis from colorectal cancer. In case 1, the patient has severe dyspnea and hypoxia due to massive right pleural effusion; therefore preoperative thoracic drainage was needed. In case 2, the patient needed paracentesis every two or three days to improve abdominal distension. After two courses of 5-fluorouracil, levofolinate, and oxaliplatin (mFOLFOX6), her ascites could be controlled by diuretics without aspiration and her general condition improved. Then she underwent operation. In case 3, the patient developed a massive pleural effusion and ascites coincident with a rapid enlargement of ovarian tumor after resection and adjuvant chemotherapy for rectal cancer. In all cases, pleural effusions and/or ascites resolved and general conditions and daily activities of the patients improved after oophorectomy. They are all currently in good health without recurrence of pleural effusion or ascites. In patients with suspected pseudo-Meigs' syndrome secondary to ovarian metastasis of colorectal cancer, operation including oophorectomy may reduce pleural effusions and/or ascites and improve the general condition.

[Two Cases of Fournier's Gangrene That Occurred during Chemotherapy for Rectal Cancer]

Two cases of Fournier's gangrene occurred during chemotherapy for advanced rectal cancer. Patients were treated using surgical debridement and antibiotic therapy. Case 1: A 66-year-old man had advanced rectal cancer with para-aortic and inguinal lymph node metastases. He received a sigmoid colostomy and chemotherapy(capecitabine, oxaliplatin, bevacizumab). Due to progression of the rectal mass, we performed radiotherapy(30 Gy)and chemotherapy(irinotecan, S-1, bevacizumab). After 14 days, he was hospitalized with a diagnosis of Fournier's gangrene with anal pain and fever. Case 2: A 63-year-old man had mucinous rectal carcinoma with sacrum invasion. He received a sigmoid colostomy and chemotherapy. Sixteen days after regorafenib therapy, as a fifth-line of chemotherapy, he was hospitalized with a diagnosis of Fournier's gangrene with hip pain, swollen perineum, and fever. There have been no reports of Fournier's gangrene occurring during chemotherapy for rectal cancer. We report 2 cases with a review of literature.

alpha-Adrenoceptor-mediated depletion of phosphatidylinositol 4, 5-bisphosphate inhibits activation of volume-regulated anion channels in mouse ventricular myocytes

BACKGROUND AND PURPOSE

Volume-regulated anion channels (VRACs) play an important role in cell-volume regulation. alpha(1)-Adrenoceptor stimulation by phenylephrine (PE) suppressed the hypotonic activation of VRAC current in mouse ventricular cells and regulatory volume decrease (RVD) was also absent in PE-treated cells. We examined whether the effects of alpha(1)-adrenoceptor stimuli on VRAC current were modulated by phosphatidylinositol signalling.

EXPERIMENTAL APPROACH

Whole-cell patch-clamp method was used to record the hypotonicity-induced VRAC current in mouse ventricular cells. RVD was analyzed by videomicroscopic measurement of cell images.

KEY RESULTS

The attenuation of VRAC current by PE was suppressed by alpha(1A)-adrenoceptor antagonists (prazosin and WB-4101), anti-G(q) protein antibody and a specific phosphoinositide-specific phospholipase C (PLC) inhibitor (U-73122), but not by antagonists for alpha(1B)-, alpha(1D)- or beta-adrenoceptor, or protein kinase C inhibitors. The inhibition of VRAC by PE was antagonized by intracellular excess phosphatidylinositol 4,5-bisphosphate (PIP(2)), while intracellular anti-PIP(2) antibody (PIP(2) Ab) inhibited the activation of VRAC currents. When cells were loaded with phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) with or without PIP(2) Ab, PE little affected the VRAC current. Extracellular m-3M3FBS (an activator of PLC) suppressed VRAC in the absence of PE, and this effect was reversed by intracellular excess PIP(2).

CONCLUSIONS AND IMPLICATIONS

Our results indicate that the stimulation of alpha(1A)-adrenoceptors by PE inhibited the activation of cardiac VRAC current via PIP(3) depletion brought about by PLC-dependent reduction of membrane PIP(2) level.

Reduction of Calponin h1 expression in human colon cancer blood vessels

AIMS

Calponin h1 (CN) is a differentiation marker of smooth muscle cells that has been reported to be down-regulated in the blood vessels of several human tumors. In this study, we examined CN expression in blood vessels in relation to the clinical and pathological features of colon cancer tissue samples.

METHODS

Fifty-six patients who had undergone colectomy for colon cancer were examined. To assess patients' disease-free survival, those who had metastasis at the time of surgical operation were excluded. Immunohistochemistry was performed by the indirect immunoperoxidase method, using serial sections made from formalin fixed and paraffin embedded tissue blocks.

RESULTS

We found that the expression of vascular CN in the peripheral region of colon cancer tissues was significantly reduced in association with tumor progression, lymphatic invasion, vascular invasion and recurrence. This reduction of CN indicated not only a decrease of pericytes and/or smooth muscle cells in tumor vessels, but also the immaturity of those cells, since CN down-regulation occurred even in alpha-smooth muscle actin-positive cells. The down-regulation of CN in vessels in the peripheral region of tumor tissues was inversely associated with the expression of VEGF (vascular endothelial growth factor), seemingly advantageous to angiogenesis.

CONCLUSION

The down-regulation of CN expression in colon cancer vasculature evaluated by immunohistochemistry may be useful in conjunction with conventional staging procedures to predict more reliable outcome and to select therapeutic treatment.

A heteroplasmic mitochondrial DNA 3310 mutation in the ND1 gene in a patient with type 2 diabetes, hypertrophic cardiomyopathy, and mental retardation

A mentally retarded 57-year-old Japanese man with maternally-inherited type 2 diabetes was found to have hypertrophic cardiomyopathy (HCM) that was associated with pathological changes in the myocardial mitochondria. The mitochondrial DNA (mtDNA) of this patient was examined and a C3310 T mutation was found in the ND1 gene, which resulted in the substitution of serine for proline. The normal 3310 mtDNA band could not be detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in mtDNA from his myocardium, pancreas, cerebral tissue, skeletal muscle, and lymphocytes. However two clones sequenced from his pancreatic tissue did not show this C3310 T mutation while forty-eight did. Mitochondria isolated from the lymphocytes of his two sisters also had this mutation. mtDNA point mutations in the ND1 gene region reported thus far have been mostly homoplasmic. However, the C3310 T point mutation that was found in this patient was heteroplasmic, which is a high level of mutation and may represent the pathogenic gene that was responsible for causing mitochondrial disease.

Younger onset myeloperoxidase-specific antineutrophil cytoplasmic antibody- (MPO-ANCA) related glomerulonephritis accompanied with nephrotic syndrome

It is known that nephrotic syndrome rarely accompanies myeloperoxidase-specific antineutrophil cytoplasmic antibody- (MPO-ANCA) related glomerulonephritis. We present a case of younger onset MPO-ANCA-related glomerulonephritis accompanied with nephrotic syndrome in a female patient. It was diagnosed through the renal biopsy and the detection of a high titer of MPO-ANCA and steroid therapy (intravenous steroid pulse therapy and oral administration), anticoagulant therapy and antiplatelet therapy were initiated. Since her nephrotic syndrome persisted in spite of the decrease of MPO-ANCA, we conducted a second renal biopsy. We found active necrotizing crescentic glomerulonephritis with a small deposition of immunoglobulin and fibrinogen on the glomeruli. To suppress her disease activity, we administered second steroid-pulse therapy and MPO-ANCA titer disappeared. However, as her nephrotic syndrome, which was accompanied by severe hyperlipidemia, persisted, we tried to treat her using low-density lipoprotein (LDL) apheresis. It was effective temporarily, but she finally fell into end-stage renal failure. We discuss here the possibility of double nephropathy by considering her clinical and renal pathologic features.

Reduced expression of actin-binding proteins, h-caldesmon and calponin h1, in the vascular smooth muscle inside melanoma lesions: an adverse prognostic factor for malignant melanoma

BACKGROUND

The structural integrity of the blood vessels such as small arteries and veins is studied less frequently in malignant tumours than is angiogenesis. Objectives To clarify the characteristics of small arteries and small veins of melanoma lesions.

METHODS

We immunohistochemically investigated various types of melanocytic tumours using antibodies specific for endothelial and vascular smooth muscle cells, and analysed the relationship between the expression of these molecules in the blood vessels and the biological characteristics of the tumours. Formalin-fixed, paraffin-embedded sections of 15 cases of benign melanocytic tumours and 64 cases of malignant melanomas were investigated.

RESULTS

Significant suppression of expression of h-caldesmon (h-CD) and calponin h1 (CNh1) was observed in the blood vessels of malignant melanomas compared with both benign melanocytic tumours and normal tissues. In particular, the level of h-CD expression was inversely correlated with the frequency of metastasis and positively correlated with the survival rate in patients with malignant melanoma.

CONCLUSIONS

These findings suggest that alterations of the tumour vessels are an important factor for the prognosis of malignant melanoma, and that suppression of h-CD and CNh1 in the blood vessels in malignant melanoma reflects a structural fragility of the vessels, leading to their easy penetration by tumour cells. Defective expression of these molecules is likely to be an important marker for metastatic potential and for poor prognosis of melanoma.

A case of mixed membranous nephropathy and purpura nephritis

We report the case of a 71-year-old man with mixed glomerular lesions, membranous and necrotizing changes. The patient had abdominal pain and purpurat on the extremities and trunk, followed by melena, and after admission to hospital, proteinuria and occult blood were noted. Laboratory findings were negative for autoimmune disease and viral hepatitis. Renal biopsy showed segmental necrotizing changes and mesangial proliferation with spike formation. Immunofluorescence revealed a granular deposition of IgA predominantly in the mesangial area in contrast to the granular IgG deposition along the glomerular capillary loops. Moreover, electron-microscopically, mesangial as well as subepithelial electron-dense deposits were observed. These data suggest that the patient had 2 distinct types of glomerulonephritis simultaneously: idiopathic membranous nephropathy and purpura nephritis.

Calponin h1 induced a flattened morphology and suppressed the growth of human fibrosarcoma HT1080 cells

Calponin h1 (CNh1) is an actin-binding protein that is expressed mainly in smooth muscle cells and is known to regulate smooth muscle contraction. Recently, re-expression of CNh1 in leiomyosarcoma cell lines is reported to suppress cell proliferation and tumorigenicity. However, little is known about the associated cellular structural and functional changes. Since CNh1 is also detected in normal fibroblasts, we hypothesised that CNh1 would also inhibit cell proliferation of the fibrosarcoma cells, HT1080, in which CNh1 is suppressed. An expression vector of human CNh1 complementary DNA was transfected into human HT1080 cells by a calcium-phosphate precipitation method. CNh1-transfected cells exhibited a flattened morphology with organised actin filaments, a significant decrease in cell motility and enhancement in adhesion to fibronectin in association with an increase in integrin alpha5beta1 expression. Anchorage-independent growth and tumorigenicity in nude mice were suppressed in the CNh1-transfected cells. Our results suggest that CNh1 may have a role as a tumour suppressor in human fibrosarcoma by influencing cytoskeletal activities.

Side chain effect on ion channel characters of Aib rich peptides

As models of ion channel proteins and naturally occurring pore-forming peptides, we designed a series of Aib rich peptides [Ac-(Aib-Xxx-Aib-Ala)(5)-NH(2) (Xxx = Lys, Glu, Ser, and Gly: BXBA-20)] to investigate the effects of the side chains of the amino acid residues Lys, Glu, Ser, and Gly on the conformation and electrophysiological properties of ion channels. The conformation of peptides and their affinity for phospholipid membranes were evaluated by CD spectroscopy. Patch-clamp experiments revealed that all BXBA-20 peptides form ion channels in DPhPC bilayers exhibiting clearly resolved transitions between the open and closed states. The channel forming frequency was in the order BKBA-20>BEBA-20>BSBA-20>BGBA-20. In the case of BKBA-20 and BEBA-20, the self-assembled conductive oligomers expressed homogeneous and voltage-independent single channel conductances. In contrast, heterogeneous conductance was observed in BSBA-20 and BGBA-20 ion channels under similar experimental conditions. From these results, we conclude that peptides with a high degree of helical conformation, high amphipathicity, high affinity for lipid membranes, and self-associating characters in vesicles are most suitable for inducing ion channels with a high frequency of occurrence. Moreover, BEBA-20, BSBA-20, and BGBA-20 channels were cation-selective, whereas the BKBA-20 channel was non-selective.

Structural fragility of blood vessels and peritoneum in calponin h1-deficient mice, resulting in an increase in hematogenous metastasis and peritoneal dissemination of malignant tumor cells

We have observed weak expression of calponin h1, which stabilizes the actin filament system, in blood vessels within human malignant tumors. This observation suggested that because of a deficiency in stabilization by calponin h1, the structure of blood vessels in malignant tumors is fragile compared with blood vessels in normal tissues. We therefore generated calponin h1-deficient (CN(-/-)) mice to examine the effect of calponin h1 on the integrity of the barrier system in blood vessels against cancer metastasis. The CN(-/-) mice exhibited morphological fragility of the tissues, including the uterus and blood vessels. In particular, we frequently observed bleeding into the surrounding tissue from blood vessels of the ocular fundus in CN(-/-) mice. In addition, mesothelial cells, which usually express calponin h1 in normal (CN(+/+)) mice, were retracted in the CN(-/-) mice. When fluorescein was injected i.v. into mice, the CN(-/-) mice exhibited a greater and more rapid leakage of fluorescein from the blood vessels of the ocular fundus compared with the CN(+/+) mice. In the CN(-/-) mice receiving i.v. inoculations of B16 melanoma cells, significantly more metastatic nodules were formed in the lung than in the CN(+/+) mice. When B16 melanoma cells were injected i.p., the severity of peritonitis carcinomatosa was greater in CN(-/-) than in CN(+/+) mice. These results indicate that calponin h1 plays an important role in the regulation of the integrity of the blood vessels and peritoneum, which in turn is an important factor influencing the frequency of cancer metastasis. The CN(-/-) mice, which exhibit fragile blood vessels and peritoneum, could serve as sensitive and useful host models to investigate cancer metastasis.

Solid-Phase synthesis of a library constructed of aromatic phosphate, long alkyl chains and tryptophane components, and identification of potent dipeptide telomerase inhibitors

Telomerase inhibitors are expected as a new candidate of therapeutic agents for cancer. Recently, we have found novel inhibitors based on the bisindole skeleton. In this study, solid-phase synthesis was applied to construct a library of inhibitors having aromatic phosphate, long alkyl chain and tryptophane components, from which a D,D-ditryptophane derivative has been identified as a new potent telomerase inhibitor with IC(50) values of 0.3 microM. A hypothetical binding model for the new inhibitors has been proposed based on the structure-activity relationship.

Development of novel telomerase inhibitors based on a bisindole unit

Telomerase is the enzyme that elongates telomere repeat at the ends of a chromosome. As high telomerase activity is observed in most cancer cells, inhibitors of human telomerase have been expected as new chemotherapeutic agents for cancer. We describe here the discovery of novel inhibitors with IC50 values in the submicromolar range. The structure of the novel inhibitors will be useful as a scaffold for construction of the library in the search for telomerase inhibitors.

Changes in cell volume induced by activation of the cyclic amp-dependent chloride channel in guinea-pig cardiac myocytes

The effects of the activation of cyclic AMP-dependent Cl- current (ICl,cAMP) on cell volume were studied at various [K+]o under isosmotic conditions in guinea-pig ventricular myocytes. The area of the cell image obtained with videomicroscopy was used as an index of cell volume. I(Cl,cAMP) was activated by adrenaline (5.5 microM). Measurements of the membrane potential (Vm) were performed by the gramicidin-perforated patch-clamp method. At 5.4 mM [K+]o with low [Cl-]o, where Vm was negative to the predicted equilibrium potential of Cl- (ECl), adrenaline sizably decreased the cell area. At high [K+]o with normal [Cl-]o, where Vm was positive to ECl, adrenaline increased the cell area; at 145.4 mM [K+]o the cell area was increased to 110% of control on average (n = 22). The cells swollen in this manner shrank when [Cl-]o was reduced to a low level in the presence of adrenaline. The results indicate that the induction of Cl- influxes (outward I(Cl,cAMP)) or effluxes (inward I(Cl,cAMP)) can lead to a cell swelling or shrinkage, respectively. The addition of BaCl2 (1 mm), a blocker of K+ channels, attenuated the adrenaline-dependent cell swelling, supporting the view that Cl- fluxes must be accompanied by cofluxes of K+ ions to affect the cell volume. The adrenaline-dependent cell swelling was inhibited by antagonizing beta-adrenergic stimulation with acetylcholine or by blocking I(Cl,cAMP) channels with glibenclamide, confirming the involvement of I(Cl,cAMP) in the adrenaline response. The results show that the activation of I(Cl,cAMP) can shrink or inflate the cardiac cells under isosmotic conditions, depending on Vm and ECl.

CyA-mediated renal interstitial and vascular lesions in the rat under low-sodium diet

Nephrotoxicity of CyA was analyzed histologically in rats fed a low-sodium diet. CyA was subcutaneously administered daily at a dose of 15 mg/kg for 10 or 35 days with or without prior uninephrectomy (UNT) in male Sprague-Dawley rats receiving a low-sodium diet (0.03% sodium). CyA-administered rats showed impaired renal function as well as tubulo-interstitial lesions, such as edema, tubular basement membrane changes, and tubular atrophy, in the cortex, especially in the subcapsular portion, within 10 days. On day 35, the tubulo-interstitial lesions were advanced with mild focal interstitial fibrosis. These lesions were mild in the UNT group compared to the non-UNT group. Immunohistochemically, CyA treatment caused an increase in number of renin-positive cells in the afferent arteriolar wall at juxtaglomerular area. These cells lost the expression of calponin, which is a marker of mature smooth muscle cells. In addition, in afferent arterioles and interlobular arteries, electron-dense fibrous bodies were found in the smooth muscle cells on days 10 and 35. Immunoelectron microscopically, these bodies showed scattered positive staining for calponin and alpha-actinin, were negative or only peripherally positive for alpha-SMA and vimentin, and were completely negative for desmin. This study revealed that CyA could cause interstitial lesions starting in the subcapsular portion of the renal cortex and vascular lesions of the preglomerular artery. Increases in number of renin granules and formation of cytoplasmic fibrous bodies in smooth muscle cells could be the forerunner of severe arteriolar wall damage.

Nodular lung disease with five year survival and unilateral pleural effusion in AL amyloidosis

A 67-year-old female patient with biopsy proven AL systemic amyloidosis developed rapidly progressive dyspnea. Chest roentgenogram and CT scan revealed a large right pleural effusion in addition to nodular lesions with bilateral hilar lymphadenopathy. The patient's serum showed IgG lambda type monoclonal gammopathy and she also had Bence Jones proteinuria. The pleural effusion was an exudate that contained many mononuclear cells and a high concentration of protein. Cardiac function was not seriously disturbed. Except for amyloidosis, no other causes for the severe pleural effusion were found. This patient was treated with chemical pleurodesis using Picibanil and a low dose of prednisolone. Eighteen months after this treatment, her right pleural effusion did not recur. Bronchopulmonary tissues are known to be frequently involved by AL systemic amyloidosis, but a nodular pattern of pulmonary amyloid deposition and a unilateral large pleural effusion are rare clinical manifestations in this disease.

Sarcoidosis with membranous nephropathy and granulomatous interstitial nephritis

A 49-year-old woman, who had been diagnosed as sarcoidosis based on bilateral hilar lymphadenopathy and lung biopsy, presented increased serum creatinine and calcium concentrations. Renal biopsy showed the presence of interstitial nephritis with non-caseating epithelioid granuloma and focal membranous transformation. Therapy with prednisolone was effective in normalizing serum creatinine, serum calcium, serum angiotensin converting enzyme, and urine beta2 microglobulin, but these abnormalities reappeared after rapid withdrawal of prednisolone. This is a rare case of sarcoidosis manifested by both membranous nephropathy and granulomatous interstitial nephritis, and indicates the necessity of long-term treatment of corticosteroid.

Molecular mechanism for pore-formation in lipid membranes by the hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata

The pore-forming activity of CEL-III, a Gal/GalNAc specific lectin from the Holothuroidea Cucumaria echinata, was examined using artificial lipid membranes as a model system of erythrocyte membrane. The carboxyfluorescein (CF)-leakage studies clearly indicated that CEL-III induced the formation of pores in the dipalmitoyl phosphatidyl choline (DPPC)-lactosyl ceramide (LacCer) liposomes effectively but not in the DPPC-glucosyl ceramide (GlcCer) liposomes or DPPC liposomes. Such a leakage of CF was strongly inhibited by lactose, a potent inhibitor of CEL-III, suggesting that the leakage is mediated through the specific binding of CEL-III to the carbohydrate chains on the surface of the liposomes. The leakage of CF from the DPPC-lactosyl ceramide liposomes was pH-dependent, and it increased with increasing pH. The immunoblotting analysis and circular dichroism data indicated that upon interaction with liposomes, CEL-III associated to form an oligomer concomitantly with a marked conformational change. Furthermore, channel measurements showed that CEL-III has an ability to form small ion channels in the planar lipid bilayers consisting of diphytanoylphosphatidylcholine and human globoside (Gb4Cer)/LacCer.

On the mechanism of the enhancement of delayed rectifier K+ current by extracellular ATP in guinea-pig ventricular myocytes

The effects of extracellular adenosine 5'-triphosphate (ATP) on the delayed rectifier K+ current (IK) were studied in guinea-pig ventricular myocytes using the whole-cell voltage-clamp technique. ATP increased IK concentration dependently with a concentration eliciting a half-maximal response of 1.86 microM and a maximal increase of about 1.8-fold. The enhancement of IK developed slowly, the effect reaching a maximum in about 1.6 min after application of ATP. The rank order of agonist potency in enhancing IK was 2-methylthio-ATP>/= ATP>>alpha,beta-methylene-ATP. The ATP response was attenuated in guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS)- loaded cells, but was not affected by pertussis toxin (PTX)-pre-treatment, indicating that a PTX-insensitive G protein is involved in the response. These features are consistent with operation of P2Y-type purinoceptors. ATP produced a further increase in IK stimulated maximally either by isoprenaline (1 microM) through protein kinase A (PKA) or by 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 nM) through protein kinase C (PKC), while 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7, 10 microM) did not affect the ATP response, suggesting that PKA and PKC do not mediate the response. ATP irreversibly enhanced IK in cells loaded with adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS, 5 mM) or okadaic acid (10 microM), a phosphatase inhibitor, suggesting that a phosphorylation step is present after the receptor stimulation. Genistein, an inhibitor of tyrosine phosphorylation, suppressed the ATP response significantly, while daidzein, an inactive analogue of genistein, had little effect on it, although both genistein or daidzein alone decreased IK. It is hypothesized that tyrosine phosphorylation plays a role in the signalling pathway involved in the enhancement of cardiac IK by P2Y-purinergic stimulation.

Enzyme level of enterococcal F1Fo-ATPase is regulated by pH at the step of assembly

The amount of F1Fo-ATPase in Enterococcus hirae (formerly Streptococcus faecalis) increases when the cytoplasmic pH is lowered below 7.6, and protons are extruded to maintain the cytoplasmic pH at around 7.6. In the present study, we found that the transcriptional activity of the F1Fo-ATPase operon was not regulated by pH. The synthesis of F1 subunits was increased 1.65 +/- 0.12-fold by the acidification of medium from pH 8.0 to pH 5.3. Western-blot analysis showed that there were F1 subunits in the cytoplasm, and the number of alpha plus beta subunits in the cytoplasm was 50% of the total number of the subunits in cells growing at pH 8.0. This decreased to 22% after shifting the medium pH to 5.3, with a concomitant 5.1-fold increase in the level of membrane-bound F1Fo-ATPase. The cytoplasmic F1 subunits were shown to be degraded, and Fo subunits not assembled into the intact F1Fo complex were suggested to be digested. These data suggest that regulation of the enzyme level of F1Fo-ATPase by the intracellular pH takes place mainly at the step of enzyme assembly from its subunits.

Contribution of mast cells to the tubulointerstitial lesions in IgA nephritis

BACKGROUND

Mast cells have never been extensively investigated in renal disease, particularly glomerulonephritis. Recent improvements in monoclonal antibody production to mast cell specific enzymes have made it possible to study mast cells in tissues more accurately and easily. Mast cells have been found to secrete basic fibroblast growth factor (bFGF) in human pulmonary fibrosis.

METHODS

Mast cells in 67 cases of IgA nephritis were investigated. Toluidine blue (TB) stainings at pH 5.0 and pH 0.5 were employed histochemically, and anti-human mast cell tryptase and chymase monoclonal antibodies were used immunohistochemically. Anti-bFGF antibody was also used immunohistochemically.

RESULTS

Mast cells were scattered in the interstitium including in fibrotic areas. TB pH 0.5-positive mast cells were more numerous than TB pH 5. 0-positive mast cells. Immunostaining with anti-tryptase monoclonal antibody detected more mast cells than the TB stainings. Mast cells in the interstitium of IgA nephritis had both tryptase and chymase. Immunoelectron microscopy showed that tryptase was exclusively localized in the specific granules of mast cells. The average number of tryptase positive mast cell in the interstitium of IgA nephritis was lower than that of T lymphocyte but more than that of macrophages. The average number of mast cells increased with the progression of interstitial fibrosis and had a significant correlation with 24-hour creatinine clearance. Using double labeled immunohistochemistry, some tryptase-positive mast cells had bFGF in their cytoplasm. Electron microscopy showed that mast cells were associated with fibroblasts and/or lymphocytes in the interstitium.

CONCLUSION

Mast cells are one of the constitutive cells in the interstitium of IgA nephritis patients and affect renal function by contributing to the interstitial fibrosis.

A repolarization-induced transient increase in the outward current of the inward rectifier K+ channel in guinea-pig cardiac myocytes

1. Outward currents of the inwardly rectifying K+ current (IKir) in guinea-pig ventricular myocytes were studied in the presence of 1 mM intracellular free Mg2+ using the whole-cell patch-clamp technique. 2. During repolarizing voltage steps following a large depolarizing pulse (> 0 mV), outward IKir increased transiently at voltages positive to the K+ equilibrium potential (EK, -84 mV for 5.4 mM extracellular [K+]). The rising phase was almost instantaneous, while the decay was exponential. The decay rate was faster at voltages closer to EK (time constants, 33.9 +/- 9.8 and 4.8 +/- 1.4 ms at -30 and -50 mV, respectively). 3. The transient outward IKir was absent when the preceding depolarization was applied from -40 mV. Larger transient currents developed as the voltage before the depolarization was shifted to more hyperpolarized levels. 4. Shift of the depolarizing voltage from > 0 mV to more negative ranges diminished the amplitudes of transient outward IKir and instantaneous inward IKir during the subsequent repolarizing steps positive and negative to EK, respectively. Since blockage of IKir by internal Mg2+ occurs upon large depolarization, and the block is instantaneously relieved at voltages negative to EK, the rising phase of the transient outward IKir was attributed to the relief of Mg2+ block at voltages positive to EK. Transient outward IKir was absent when intracellular [Mg2+] was reduced to 10 microM or lower. 5. Prolongation of the repolarizing voltage step increased the amplitude of time-dependent inward IKir during the subsequent hyperpolarization, indicating the progress of a gating process (presumably the channel block by intracellular polyamine) during the decaying phase of outward IKir. 6. Progressive prolongation of the depolarizing pulse (> 0 mV) from 100 to 460 ms decreased the transient outward IKir amplitude during the subsequent repolarizing step due to slow progress of the gating (polyamine block) at > 0 mV. 7. Current-voltage relations measured using repolarizing ramp pulses (-3.4 mV ms-1) showed an outward hump at around -50 mV, the magnitude of which increased as the voltage before the conditioning depolarization (10 mV) was shifted to more negative levels. With slower ramp speeds (-1.5 and -0.6 mV ms-1), the hump was depressed at voltages near EK. 8. Our study suggests that the relief of Mg2+ block may increase outward IKir during repolarization of cardiac action potentials, and that the resting potential, the level/duration of action potential plateau and the speed of repolarization influence the outward IKir amplitude. 9. A kinetic model incorporating a competition between polyamine block and Mg2+ block was able to account for the time dependence of outward IKir.

Intracellular Mg2+ depletion depresses the delayed rectifier K+ current in guinea pig ventricular myocytes

The effects of various [Mg2+]i, particularly low [Mg2+]i, on the delayed rectifier K+ current (IK) were studied in guinea pig ventricular myocytes with the patch clamp technique. The magnitude of IK was evaluated from the amplitude of its tail current elicited on repolarization following the depolarizing steps. The pipette-perfusion technique was also used. The initial variations of IK magnitude were dependent on [Mg2+]i in the internal solutions with which the whole-cell recording was begun. With 0.03 to 1 mM [Mg2+]i, IK was relatively stable after patch rupture, showing a minimal decay with time; with 3 mM [Mg2+]i, IK rapidly declined; with [Mg2+]i, less than 0.01 mM IK transiently increased after patch break, but declined progressively thereafter as the magnitude of IK decreased to about 30% of the initial magnitude in 10 min. The decline of IK at low [Mg2+]i showed the following features. The decline was accompanied little by changes in the voltage-activation relation or by changes in the kinetics of current deactivation. The decline was not related to changes in [Ca2+]i and was also observed in ATP gamma S-loaded, isoprenaline-stimulated cells, in which IK channels were presumed to be persistently phosphorylated. An application of okadaic acid did not prevent the decline of IK during Mg2+ depletion. It is suggested that a presence of [Mg2+]i higher than 0.01 mM is required to maintain IK in guinea pig ventricular cells. The depression of IK at low [Mg2+]i appears to involve a phosphorylation-dephosphorylation-independent mechanism.

Swelling-induced Cl- current in guinea-pig atrial myocytes: inhibition by glibenclamide

1. Whole-cell currents were recorded from guinea-pig atrial myocytes using the patch-clamp technique under conditions designed to block K+ channels, Ca2+ channels and electrogenic transporters. 2. Exposure of atrial myocytes to the hyposmotic external solution (Na+ reduction to about 70% of control) resulted in hyposmotic cell swelling which was associated with activation of an outwardly rectifying Cl- current (ICl,swell). 3. Whereas the activation of ICl,swell was not significantly affected by replacement of ATP in the pipette solution with the non-hydrolysable ATP analogue 5'-adenylyl-imidodiphosphate (AMP-PNP), its activation was greatly reduced in cells dialysed with an ATP-free pipette solution, thus indicating that the activation process of ICl,swell requires the presence of intracellular ATP, but not its hydrolysis. 4. Bath application of glibenclamide produced a concentration-dependent block of ICl,swell with a half-maximal inhibitory concentration (IC50) of 60.0 microM and a Hill coefficient of 2.1. The maximal effect (100% inhibition) was obtained with 500 microM glibenclamide. The steady-state inhibition showed little voltage dependence, while glibenclamide at concentrations of more than 100 microM inhibited the outward ICl,swell more rapidly than the inward ICl,swell. The glibenclamide inhibition was fully reversible after removal of the drug, even when a maximal effect (full inhibition) was achieved at a high drug concentration (500 microM). 5. These results show that (i) glibenclamide is one of the most potent inhibitors of guinea-pig atrial ICl,swell, and (ii) atrial ICl,swell and the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- currents are almost equally sensitive to inhibition by glibenclamide.

Selective enhancement of the slow component of delayed rectifier K+ current in guinea-pig atrial cells by external ATP

1. The effects of external ATP on the rapidly and slowly activating components (IKr and IKs, respectively) of the delayed rectifier K+ current (IK) in guinea-pig atrial myocytes were determined using the whole-cell configuration of the patch-clamp technique. 2. An envelope of tails test was conducted by applying depolarizing pulses to +40 mV from a holding potential of -40 mV for various durations between 50 ms and 2 s under control conditions and during exposure to 50 microM ATP. The ATP-induced IK, obtained by digital subtraction, exhibited a constant ratio (0.37) of the tail current to time-dependent current, regardless of the pulse duration. This current ratio was compatible with the predicted ratio of the driving force at +40 and -40 mV for a non-rectifying K+ conductance, suggesting that the ATP-induced IK is due primarily to IKs. 3. The amplitude of IKr isolated from the IK enhanced by ATP, determined as an E-4031 (5 microM)-sensitive current, was similar to the control magnitude of IKr, thus showing that external ATP did not cause an increase in IKr. 4. The voltage-dependent activation of the ATP-induced IK during 500 ms depolarizing test pulses could be described by a Boltzmann equation with a half-activation voltage (V1/2) of 11.5 mV and slope factor (k) of 12.0 mV, which were close to those of IKs (V1/2 of 12.1 mV and k of 12.3 mV), determined as an E-4031-resistant IK, under the same isochronal (500 ms) activation conditions. 5. These results provide evidence to suggest that extracellular ATP selectively potentiates the slow component of IK (IKs), with no measurable effects on IKr, in guinea-pig atrial myocytes.

Modulation of the muscarinic K+ channel by P2-purinoceptors in guinea-pig atrial myocytes

1. Activation of muscarinic K+ (KACh) channels by P2-purinergic agonists, such as ATP, decreases monotonically in the continued presence of agonist. We investigated the mechanisms underlying this process of decline in guinea-pig atrial myocytes using the patch-clamp technique. 2. External ATP reversibly depressed the acetylcholine (ACh, 5.5-11 microM)-induced KACh current in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50) of 5.4 microM. 3. External ATP irreversibly reduced guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S)-induced KACh current both in control and pertussis toxin (PTX)-pretreated cells, suggesting (i) that the ATP-induced inhibition of KACh current occurred at some step(s) downstream from the activation of the PTX-sensitive G protein, GK, and (ii) that a PTX-insensitive G protein was involved in the signal transduction pathway. 4. The potency order of ATP analogues in reducing KACh current was ATP > or = 2-methylthio-ATP > or = alpha, beta-methylene-ATP, indicating involvement of a P2Y-type purinoceptor. 5. In the cell-attached patch recording, ATP (100 microM) applied to the bath solution reduced the activity of the KACh channels activated by ACh in the pipette, in two out of eight experiments, suggesting the possible involvement of cytosolic second messengers in the inhibition of KACh channels. 6. The ATP-induced reduction of KACh current was not affected by a protein kinase C inhibitor, 1-(5-isoquinolinesulphonyl)-2-methylpiperazine dihydrochloride (H-7), suggesting that this response was not mediated by the activation of protein kinase C. 7. These results demonstrate that, in addition to the membrane-delimited activation through GK, external ATP causes an inhibition of the KACh channel probably by activating a PTX-insensitive G protein and cytosolic second messenger(s), which may underlie the monotonic decrease of the ATP-activated KACh current.

Microwave continuous sterilization of injection ampoules

A new microwave continuous sterilizer (MWS) for applying microwave dielectric heating as an alternative to an autoclave was developed. The developmental objectives of the MWS were: 1. Achieving sufficient sterilization for the drugs containing heat-sensitive ingredients. 2. Measuring and recording sterilization temperature of each ampoule. 3. Ensuring automatic continuous operation and linkage with the preceding and following machines in an injection ampoule production process. The temperature of the drug solution in an ampoule was heated to 140 degrees C within about 30 seconds by the MWS. Target F0 value is achieved through the maintaining heater to maintain the target temperature for 12 seconds. Ampoules are cooled with air and water after completion of heating. The MWS is capable of processing 150 ampoules per minute. The newly developed techniques which minimized temperature distribution of heated ampoule solution were: 1. Microwave irradiation in a direction opposite to the direction of ampoules transportation. 2. Microwave irradiation in the lower part of ampoule solution (i.e., heating up the drug solution by thermal convection.) 3. Microwave power control by feedback of measured temperatures. 4. Heating rate control corresponding to the dielectric property of ampoule solution. The drug stability test was performed using 3% pyridoxamine phosphate solution, and the inactivation of spores in 3% pyridoxamine phosphate solution was examined using Bacillus stearothermophilus ATCC 7953 spores. The MWS was proved to have an adequate efficiency of sterilization with less chemical degradation of the contents than an autoclave.

Cervical Castleman's disease associated with benign M-proteinemia: report of a case

We report the unusual case of a 77-year-old man with cervical Castleman's disease associated with benign M-proteinemia. The patient was found to have an anterior cervical tumor during a follow-up examination after surgery for early gastric cancer, at which time blood biochemistry tests revealed M-proteinemia at the position of beta-globulin with a high level of IgG and low levels of IgA and IgM. Serum protein immunoelectrophoresis revealed M-protein consisting of the IgG-k chain, and urine protein immuno-electrophoresis demonstrated Bence Jones protein consisting of the chain. No abnormalities were noted in bone marrow aspiration or bone scintigram. The results of imaging and fine-needle aspiration biopsy of the tumor led to a pre-operative diagnosis of cervical malignant lymphoma with suspected M-proteinemia derived from this disease, and resection of the anterior cervical tumor with bilateral neck dissection was performed. Histopathological examination subsequently demonstrated four mixed-type tumors of Castleman's disease. The pathogenesis of Castleman's disease remains unknown; however, we speculate that the complication of benign M-proteinemia in this patient was not incidental, but caused by an underlying immunological abnormality of the B cells.

Total synthesis of VIM-2 ganglioside isolated from human chronic myelogenous leukemia cells

A total synthesis of the tumor-associated glycolipid antigen, VIM-2, is described [2]. Phenyl 2,3,4-tri-O-benzoyl-6-O-benzyl-beta-D-galactopyranosyl-(1-->4)-6-O-benzy l-2- deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside (7), a key intermediate prepared by condensation of phenyl 6-O-benzyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside (6) and 2,3,4-tri-O-benzoyl-6-O-benzyl-alpha-D-galactopyranosyl bromide (5), was glycosylated with methyl 2,3,4-tri-O-benzyl-1-thio-beta-L-fucopyranoside (8) to give the trisaccharide donor 9, which, on coupling with 2-(trimethylsilyl)ethyl 2,4,6-tri-O-benzyl-beta-D-galactopyranosyl-(1-->4)-2,3,6-tri-O-benzyl-be ta-D- glucopyranoside (10), afforded the pentasaccharide 11. The regioselective glycosylation of 12 (derived by O-debenzoylation of 11) with 7 gave the heptasaccharide 13, which was converted by treatment with hydrazine monohydrate and subsequent N-acetylation into the hexasaccharide acceptor 14. The stereo- and regio-selective glycosylation of 14 with methyl (phenyl 5-acetamido-4,7,8,9-O-benzoyl-3,5-dideoxy-2-thio-D-glycero-beta-D-galact o-2- nonulopyranosid)onate (16) gave the desired octasaccharide 18. Hydrogenolytic removal of the benzyl groups in 18 and successive O-acetylation, removal of the 2-(trimethylsilyl)ethyl group, and treatment with trichloroacetonitrile gave the alpha-trichloro-acetimidate 21, which was then coupled with (2S,3R,4E)-2-azido-3-O-(tert-butyldiphenylsilyl)-4-octade cene-1,3-diol (22) to give 23. Compound 23 was transformed, via selective reduction of the azido group, N-introduction of octadecanoic acid, O-desilylation, O-deacylation, and saponification of the methyl ester group, into the title VIM-2 ganglioside 26.

Activation of the muscarinic K+ channel by P2-purinoceptors via pertussis toxin-sensitive G proteins in guinea-pig atrial cells

1. Whole-cell voltage clamp and cell-attached patch-clamp techniques were applied to single atrial myocytes enzymatically dissociated from adult guinea-pig hearts. 2. In whole-cell clamp conditions, external applications, of ATP activated the muscarinic K+ (KACh) current, identified by its inward rectification, its reversal potential near the calculated K+ equilibrium potential (EK) and its relaxation properties during step changes of whole-cell membrane potential. Theophylline, an antagonist for Pi-purinoceptors, did not affect the action of ATP on the KACh current, indicating that the response was evoked through P2-purinoceptors. 3. The concentration-response relationship for ATP was well described by a Hill equation with a half-maximal concentration of 1.84 microM and a Hill coefficient of 0.94. ATP (100 microM) produced a maximal increase of the KACh current to 10.92 microA microF-1, which corresponds to 44.9 and 80.9% of the maximal increases evoked by ACh (10 microM) and adenosine (100 microM), respectively. 4. The activation of KACh current gradually declined to a steady level despite the continuous presence of ATP (desensitization). Recovery from the desensitization was relatively rapid with a half-time of approximately 1.5 min. 5. The activation of KACh current by ATP was completely abolished by pre-incubating myocytes with pertussis toxin (PTX, 5 micrograms ml-1), indicating that P2-purinoceptors are coupled to PTX-sensitive G proteins to activate the KACh channel. 6. In the cell-attached patch recording, ATP (5 microM) applied to the pipette solution enhanced the activity of a channel with single-channel conductance of 52.7 +/- 0.9 pS (mean +/- S.E.M., n = 10), reversal potential near EK and mean open time of 1.1 +/- 0.1 ms. These conductance and kinetic properties are identical to those of the KACh channel in the heart. In contrast, ATP applied to the bath solution did not significantly affect the basal activity of KACh channel openings. These observations suggest that the mechanism coupling the P2-purinoceptor to the activation of the KACh channel involves membrane-delimited component(s) rather than soluble second messenger(s). 7. These results strongly suggest a direct coupling of the P2-purinoceptor to the KACh channel through PTX-sensitive G proteins, analogous to the coupling mechanism of the muscarinic ACh receptor and Pi-purinoceptor to this channel.

Enhancement of delayed rectifier K+ current by P2-purinoceptor stimulation in guinea-pig atrial cells

1. We studied the effects of P2-purinoceptor stimulation on the delayed rectifier K+ current (IK) in guinea-pig atrial myocytes using a whole-cell voltage-clamp technique. 2. External application of ATP increased IK, evoked by a 500 ms depolarizing pulse from a holding potential of -40 mV, under conditions in which the L-type Ca2+ channel was blocked; the effect was dose dependent with a half-maximal concentration (K1/2) of 0.95 microM. ATP (50 microM) produced a maximal increase of IK of about a factor of 2. 3. External ADP also enhanced IK in a dose-dependent manner with a K1/2 of 3.65 microM, whereas adenosine (100 microM) failed to evoke this response. Theophylline (500 microM), a blocker of the Pi-purinoceptor, did not antagonize the stimulating action of ATP on IK. These results indicate that IK was enhanced via P2-purinoceptors. 4. External ATP or ADP did not produce a significant change in the current kinetics of IK. 5. Pre-incubation of the atrial myocytes with pertussis toxin (PTX, 5 micrograms ml-1) did not affect the stimulating action of ATP on IK, indicating that PTX-sensitive G proteins did not mediate the ATP action. 6. The enhancement of IK by ATP developed slowly; the effects usually reached a maximum approximately 30-60 s after the application of ATP. This suggests the involvement of a diffusible cytosolic second messenger(s) in the response. ATP could further increase IK after maximal enhancement by isoprenaline (0.5-1.0 microM), suggesting that the intermediate steps were independent of cyclic AMP-dependent protein kinase (protein kinase A). 7. Potentiation of IK by ATP was not attenuated by either (i) pretreatment of the cells with 5 microM 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine dihydrochloride (H-7) or (ii) intracellular perfusion of 20 mM 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), suggesting that protein kinase C and intracellular Ca2+ did not mediate the response. 8. It is concluded that the activation of P2-purinoceptors increases IK through intracellular mechanisms independent of protein kinase A, protein kinase C or intracellular free Ca2+ in guinea-pig atrial myocytes.