Glutathione-dependent inactivation of sodium-dependent phosphate transport across rat renal brush-border membrane

Thiol/disulfide is fundamental in protein function; we previously observed an inhibitory effect of thiol oxidants on the Na-dependent phosphate (Pi) uptake into renal brush border membrane vesicles (BBMV). We examined whether oxidation of glutathione (GSH) is involved in the mechanism. Vesicular thiols were measured by liquid chromatography. BBMV were incubated with reagents before an influx of Pi. Diamide (5 mM) reduced the capacity of the Pi uptake. Subsequent treatment with dithiothreitol (5 mM) blocked the inhibitory effect of diamide. Vesicular GSH was not modified only by the incubation, whereas it was oxidized by the treatment with diamide, and reduced by dithiothreitol. Furthermore, in vivo treatment with cAMP provided GSH-depleted BBMV without any influence on Pi uptake. Diamide did not inhibit the transport of Pi into GSH-depleted vesicles, but it did inhibit the uptake when GSH was introduced into the vesicles. In conclusion, a GSH-dependent mechanism is involved in the inhibitory effect of diamide on sodium-dependent Pi transport across the renal brush-border membrane.     

Synchronous occurrence of early neuroendocrine carcinoma and tubular adenocarcinoma in the stomach

This report describes a patient with early neuroendocrine carcinoma (NEC) and tubular adenocarcinoma in the stomach. A 74-year-old Japanese male experienced epigastralgia. Endoscopic examination revealed two small lesions; one was an elevated lesion with ulceration at the posterior wall of the pre-pylorus and the other was a depressed lesion at the greater curvature of the antrum. Pathological diagnosis of the biopsies indicated poorly differentiated adenocarcinoma from the lesion on the pre-pylorus and well differentiated adenocarcinoma from the lesion on the antrum. He was referred to the surgical outpatient clinic with early double cancer of the stomach. A distal partial gastrectomy with lymph node dissection was performed. A histopathological examination revealed NEC at the lesion on the pre-pylorus and well differentiated tubular adenocarcinoma at the lesion on the antrum. These two lesions were completely separate from each other. Therefore, this case is thought to demonstrate the synchronous occurrence of early NEC and tubular adenocarcinoma in the stomach.     

Lucifer Yellow Slows Voltage-Gated Na+ Current Inactivation in a Light-Dependent Manner in Mice

Lucifer Yellow CH (LY), a membrane-impermeant fluorescent dye, has been used in electrophysiological studies to visualize cell morphology, with little concern about its pharmacological effects. We investigated its effects on TTX-sensitive voltage-gated Na⁺ channels in mouse taste bud cells and hippocampal neurons under voltage-clamp conditions. LY applied inside cells irreversibly slowed the inactivation of Na⁺ currents upon exposure to light of usual intensities. The inactivation time constant of Na⁺ currents elicited by a depolarization to −15 mV was increased by fourfold after a 5 min exposure to halogen light of 3200 lx at source (3200 lx light), and sevenfold after a 1-min exposure to 12 000 lx light. A fraction of the Na⁺ current became non-inactivating following the exposure. The non-inactivating current was ≈ 20 % of the peak total Na⁺ current after a 5 min exposure to 3200 lx light, and ≈ 30 % after a 1 min exposure to 12 000 lx light. Light-exposed LY shifted slightly the current-voltage relationship of the peak Na⁺ current and of the steady-state inactivation curve, in the depolarizing direction. A similar light-dependent decrease in kinetics occurred in whole-cell Na⁺ currents of cultured mouse hippocampal neurones. Single-channel recordings showed that exposure to 6500 lx light for 3 min increased the mean open time of Na⁺ channels from 1.4 ms to 2.4 ms without changing the elementary conductance. The pre-incubation of taste bud cells with 1 mM dithiothreitol, a scavenger of radical species, blocked these LY effects. These results suggest that light-exposed LY yields radical species that modify Na⁺ channels.     

Midkine protects hepatocellular carcinoma cells against TRAIL-mediated apoptosis through down-regulation of caspase-3 activity

BACKGROUND: It is believed that midkine (MK), a heparin-binding growth factor, plays an important role in carcinogenesis. However, the biologic mechanism of MK in hepatocellular carcinoma has not been clarified to date. The objective of the current study was to investigate the antiapoptotic role of MK in a human hepatoma cell line. METHODS: The human hepatoma cell line HepG2 was used to study the antiapoptotic effect of MK. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/actinomycin D (ActD)-induced apoptosis was detected using a 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulphophenyl)-2H-tetrazolium monosodium salt (WST-8) assay, a caspase-3 activity assay, a caspase-8 activity assay, and flow cytometric analysis. RESULTS: TRAIL had a potent, dose-dependent inductive effect on cell death in HepG2 cells, for which viable cell counts decreased to 6.3% of the control count at a TRAIL concentration of 100 ng/mL in the presence of 500 ng/mL ActD. Flow cytometry was used to demonstrate that apoptosis induced by TRAIL/ActD was in fact the cause of cell death. According to the WST-8 assay, MK pretreatment resulted in the suppression of TRAIL/ActD-mediated apoptosis in HepG2 cells, although cell viability did not increase when HepG2 cells were treated with MK alone. Caspase-3 activity was down-regulated when MK was added, but caspase-8 activity was high in both the absence and presence of MK. CONCLUSIONS: The results of the current study indicate that MK acts as an antiapoptotic factor in HepG2 cells through the down-regulation of caspase-3 activity.     

Repetitive application of caffeine sensitizes caffeine-induced Ca release in bullfrog sympathetic ganglion neurons

Cytosolic free calcium concentration ([Ca(2+)](i)) was recorded from cultured bullfrog sympathetic ganglion cells loaded with the Ca(2+)-indicator Fura-2 or Fura-6F. Repetitive application of caffeine at a low concentration, which either failed to produce any [Ca(2+)](i) elevation or induced a small gradual increase in [Ca(2+)](i) at first challenge, produced a drastic increase in the amplitude of Ca(2+) release (caffeine response). The caffeine response eventually reached peak amplitude and then remained constant even if caffeine application were continued. This augmentation was maintained for up to 2 h, and was achieved not only by repetitive application but also by a long exposure of caffeine. However, this augmentation was neither achieved by repetitive administration of high K(+)-solution, nor caused by inhibition of phosphodiesterase by caffeine. The repetitive or sustained application of caffeine is suggested to increase the caffeine sensitivity of the calcium release channel to calcium, thus causing the potentiation of the caffeine response.     

Malignant Hemangiopericytoma in the Pelvic Cavity Successfully Treated by Combined-Modality Therapy: Report of a Case

A 55-year-old Japanese woman underwent extirpation of a malignant hemangiopericytoma in the pelvic cavity, followed by postoperative irradiation. An abdominal computed tomography scan 3 years later revealed a local recurrent tumor, 12 cm in diameter, in the pelvic cavity, for which transarterial embolization was done, followed by excision of the tumor employing Hartmann's procedure. Although an unresectable part of the recurrent tumor remained, postoperative irradiation reduced its size remarkably. The patient is still alive 7 years 2 months after her first operation, but with more recurrent tumors in the abdominal wall and around the bilateral iliac arteries. Because hemangiopericytoma often recurs or metastasizes after a prolonged disease-free interval, close long-term follow-up is necessary after the operation. Combined-modality therapy against the recurrent or unresectable disease may result in a good prognosis. Received: April 3, 2002 / Accepted: November 19, 2002 RID="*" ID="*" Reprint requests to: T. Torigoe     

Repetitive application of caffeine sensitizes caffeine-induced Ca2+ release in bullfrog sympathetic ganglion neurons

Cytosolic free calcium concentration ([Ca(2+)](i)) was recorded from cultured bullfrog sympathetic ganglion cells loaded with the Ca(2+)-indicator Fura-2 or Fura-6F. Repetitive application of caffeine at a low concentration, which either failed to produce any [Ca(2+)](i) elevation or induced a small gradual increase in [Ca(2+)](i) at first challenge, produced a drastic increase in the amplitude of Ca(2+) release (caffeine response). The caffeine response eventually reached peak amplitude and then remained constant even if caffeine application were continued. This augmentation was maintained for up to 2 h, and was achieved not only by repetitive application but also by a long exposure of caffeine. However, this augmentation was neither achieved by repetitive administration of high K(+)-solution, nor caused by inhibition of phosphodiesterase by caffeine. The repetitive or sustained application of caffeine is suggested to increase the caffeine sensitivity of the calcium release channel to calcium, thus causing the potentiation of the caffeine response.     

Primary pericardial synovial sarcoma

A 57-year-old man was admitted to our hospital with cardiomegaly on a chest roentgenogram. A mediastinal tumor was observed during a chest computed tomographic scan and the patient was diagnosed with pericardial synovial sarcoma as a result of a tumor biopsy. Surgery, radiotherapy and chemotherapy were carried out, and although the tumor temporarily decreased in size, it subsequently increased and the patient died approximately 3 years following the initial medical examination. Most synovial sarcomas commonly occur in the vicinity of the joints of the extremities. Therefore, we herein report a rare case of synovial sarcoma which occurred in the pericardium.     

A new oval multichannel port to facilitate reduced port distal gastrectomy

Background: This report describes the techniques and outcomes of reduced port distal gastrectomy (RPDG) using a new oval multichannel port. Material and methods: We performed reduced port distal gastrectomy through the E·Z Access? oval type device with three trocars in the umbilical incision, plus the use of additional 5 mm and 2 mm ports. All routine procedures performed in conventional laparoscopic distal gastrectomy (CLDG) were achieved in RPDG. Results: We employed this technique without the use of additional trocars or conversion to laparotomy in all 25 patients. The median length of the operation was 340 (range, 220–487) minutes, and the median estimated blood loss was 30 (range, 5–440) ml. Neither major postoperative complications, such as anastomotic leakage and stricture, nor postoperative mortality were observed. The mean length of the hospital stay was 11 days. The umbilical wound was indistinct. The patients were also highly satisfied with the cosmetic outcome. Conclusion: Reduced port surgery using the E·Z Access? oval type device was successfully applied for gastric cancer. This method is technically feasible, produces superior cosmetic results and thus could be an attractive surgical option for gastric cancer patients.