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It is known that opioid analgesics given systemically have limited distribution into the brain because of their interaction with P-glycoprotein (P-gp), an ATP-dependent efflux pump acting at the blood-brain barrier (BBB). We previously found that morphine and fentanyl showed higher analgesic potencies in P-gp–deficient mice compared with those in wild-type mice, suggesting that their analgesic effects are considerably dependent on P-gp expression. In this study, we focused on individual differences in the analgesic effectiveness of morphine, in cortical P-gp expression, and in basal P-gp ATPase activity in male ICR mice. We found that there were 3- to 10-fold differences between the magnitude of morphine analgesia (3 mg /kg, s.c.; tail-pinch method) in mice. Furthermore, there was a significant negative correlation between morphine’s analgesic effects and individual P-gp expression in the cortex as estimated by western blot analysis. In addition, basal P-gp ATPase activities in isolated membrane preparations of brain capillary endothelial cells (BCECs) were negatively correlated with the magnitude of the analgesic effect of morphine. These results indicate that the individual differences in morphine analgesia may be due to some functional or quantitative differences in individual P-gp in BCECs, acting at the BBB.

We evaluated the interaction between electroacupuncture (EA)-induced antinociception and an endogenous anti-analgesic system. EA was applied to the ST-36 acupoint for 45 min in male Sprague-Dawley rats, and pain thresholds were assessed by the hind-paw pressure test. EA produced a marked increase in pain thresholds and its antinociceptive action was completely reversed by naloxone (5 mg/kg). The analgesic effects of subcutaneous morphine (7 mg/kg) following EA stimulation were significantly attenuated. The attenuation of morphine analgesia was inversely proportional to the time intervals between EA termination and morphine injection, and the effect was not observed 120 min after EA stimulation. The analgesic effects of i.t. morphine (10 µg), but not i.c.v. morphine (25 µg), following EA were also attenuated. On the other hand, systemic morphine (7 mg/kg)-induced hyperthermia was not affected by EA. Moreover, i.c.v. morphine, but not i.t. morphine, produced hyperthermia. The i.c.v. morphine-induced hyperthermia was not affected by EA, similar to i.c.v. morphine analgesia. These results suggest that the attenuation of morphine analgesia following EA, that is, the activation of an endogenous anti-analgesic system, is closely related to the activation of an analgesic system by EA and that the spinal cord plays a critical role in the activation of the endogenous anti-analgesic systems.

Morphine’s analgesic actions are thought to be mediated through both the central and peripheral nervous systems. L-type calcium channel blockers have been reported to potentiate the analgesic effects of morphine, but the locus of this interaction is not known. In this experiment, we examined the site of verapamil-induced potentiation of morphine analgesia in mice using the quaternary opioid receptor antagonist naloxone-methiodide (NLX-M). Subcutaneous injections of morphine increased locomotor activity and serum corticosterone level, which are mediated by the central nervous system. These central effects were not antagonized by 0.1 mg/kg of NLX-M, whereas this dose of NLX-M partially antagonized the analgesic effect of morphine. Treatment with verapamil potentiated morphine analgesia in a dose-dependent manner. The verapamil-induced potentiation of morphine analgesia was abolished by pretreatment with NLX-M (0.1 and 1 mg/kg). These findings suggest that peripheral mechanisms partially contribute to morphine analgesia and mediate the potentiation of morphine analgesia by verapamil.

The present study was designed to investigate the pharmacokinetic interaction of morphine with three classes of L-type calcium channel blockers (CCB) and its relationship to morphine-induced mechanical antinociception in mice. The CCB classes were benzothiazepine (diltiazem), dihydropyridine (nimodipine), and phenylalkylamine (verapamil). Each of the three classes of L-type CCB (diltiazem, 40 and 80 mg/kg; nimodipine, 40 mg/kg; verapamil, 40 mg/kg), when administered prior to morphine (4 mg/kg, s.c.), potentiated the analgesic effect of morphine and markedly increased the level of morphine in serum. Pretreatment with diltiazem (40 and 80 mg/kg) and verapamil (40 mg/kg) also increased morphine level in the brain. However, these drugs produced less increase in morphine level in the brain than they produced in serum (i.e., they decreased the brain-to-serum ratio of morphine). Pretreatment with nimodipine (40 mg/kg) did not affect the morphine level in the brain and also decreased the brain-to-serum ratio of morphine. When morphine (3.2 – 100 mg/kg, s.c.) was injected alone, the brain-to-serum ratio of morphine was constant, regardless of the morphine dose. These results suggest that increases in morphine concentration in peripheral blood may be, at least in part, involved in the ability of L-type CCBs to potentiate the analgesic effect of morphine.

Recent studies on noninvasive recordings from human brain have shown the existence of taste-elicited activation areas in the cerebral cortex. While functional MRI (f-MRI) and positron CT (PET) are often used for these studies, the magnetoencephalogram (MEG) is the most commonly used instrument for these noninvasive measurements. One advantage of the MEG measurements is the ability to measure rapid taste-elicited time-course data. In this current study, we used brain magnetic fields to quantitate the stimulus latencies evoked by different taste stimuli that use different peripheral transduction mechanisms. Recent work has shown that taste stimuli that presumably act through different transduction processes show different MEG-measured latencies. Here, we measured the latencies due to citric acid and sucrose and compared these with the latency due to the action of the taste-modifying substance contained in miracle fruit during stimulation by citric acid. Miracle fruit has the property of changing the sour taste of acids to sweet taste. The use of this taste-modifying substance allows us to compare the latency of two very different sweet-taste-evoking substances.

The effects of cPrG·HCl and epirubicin on the suppression of cell growth were examined on human breast cancer cell line (MDA-MB-231). Either cPrG·HCl or epirubicin alone showed a tumor growth inhibition in a time- and dose-dependent manner, however, the combinatory use of cPrG·HCl together with epirubicin resulted in prominent synergistic effects on the breast cancer cells. In the in vitro studies, the combinatory use of these two drugs accelerated apoptotic cell death as revealed by morphological changes as well as by the appearance of subG$\_1$ population by flow cytometry. In addition, confocal microscopy revealed that the accumulation of epirubicin in nucleus increased apparently when cPrG·HCl were present. In the in vivo assay, nude mice bearing xenografted tumor cells received 4 weeks of intraperitoneal administration of cPrG·HCl and epirubicin. After 12 days, the combinatory treatment significantly suppressed the tumor growth compared to the controls. The TUNEL staining revealed that tumor cells in cPrG·HCl plus epirubicin-treated mice exhibited a higher apoptotic rate. In addition, $^31$P-NMR studies on the xenografted tumor revealed that cPrG·HCl lowered tumor pHi (below pH 6.9), while it did not affected muscle pHi. No pathological changes were observed in any intrinsic organs and the serum alanine aminotransferase levels remained within normal limits among the groups. These results suggest that the combinatory use of cPrG·HCl and epirubicin may be useful for breast cancer therapy.

Cycloprodigiosin hydrochloride (cPrG • HCl), a novel H⁺/Cl^– symporter, induces acidification of the cytosol and leads to apoptosis in rat and human liver cancer cells. In the present study, the effect of cPrG • HCl on a promyelocytic leukemia cell line (HL-60) was examined. cPrG • HCl lowered intracellular pH and induced apoptosis through up-regulation of Fas ligand, activation of stress-activated protein kinase (SAPK/JNK) and caspase. Apoptosis induced by cPrG • HCl was strongly suppressed when a cell-permeable weak base, imidazole, was present, indicating that cytosol acidification introduced by cPrG • HCl triggered caspase activation, leading to apoptosis. Concomitantly, cell differentiation into monocyte was also induced by cPrG • HCl both morphologically and functionally. However, the cPrG • HCl-induced differentiation was not suppressed by addition of imidazole, indicating that the differentiation process is unrelated to cytosol acidification. Further, the differentiation induced by cPrG • HCl was blocked by tyrosine kinase inhibitors (lavendustin A and HMA) but unaffected by the inhibitors of A-kinase (H-89) or C-kinase (H-7). Taken together, these findings suggest that cPrG • HCl, through apoptosis and differentiation induction, may be useful in leukemia treatment. Int. J. Cancer 88:121–128, 2000. © 2000 Wiley-Liss, Inc.

Abstract: The effect of cycloprodigiosin hydrochloride (cPrG  HCl), a H+/Cl− symporter, on five human breast cancer cell lines (KPL-1, T-47D, MCF-7, MKL-F, and MDA-MB-231), a human breast epithelial cell line (HBL-100), and a human fibroblast cell line (WI-38–40) was examined. cPrG  HCl inhibited the growth of all five breast cancer cell lines (IC50: 0.46–0.62 μM) and slightly inhibited HBL-100 and WI-38–40 cell growth (IC50: 1.75 μM and 2.26 μM respectively). cPrG  HCl treatment in KPL-1 cells increased the pH of acidic organelles, decreased intracellular pH, and caused apoptosis, which was confirmed by the appearance of a sub-G1 population by flow cytometry and DNA fragmentation. In addition, cPrG  HCl-induced apoptosis was strongly suppressed by imidazole, a cell-permeable base, suggesting that intracellular acidification was essential for the apoptosis. Further, cPrG  HCl treatment up-regulated Bax and Bak expression, down-regulated Bcl-2 expression, and activated caspase-3. Therefore, the intracellular acidification by cPrG  HCl treatment suppressed the growth of human breast cancer cell lines by inducing apoptosis.

Conjugation reaction of methazolamide with glutathione and its subsequent reactions were studied in vitro. Glutathione, cysteinylglycine, and cysteine conjugates of methazolamide were chemically synthesized. All of the three compounds showed absorbance below 330 nm, with maximal absorbance at ∼300nm. At the wavelengths below 220 nm, absorbance was proportional to the number of the amino acids each compound had. Amino acid analysis of the glutathione conjugate showed that the conjugation reaction involved the cysteine residue of glutathione. In order to identify the chemical structure of the reaction product, cysteine conjugate was subjected to infrared, proton nuclear magnetic resonance, and mass spectral analyses. These studies indicated that the cysteine conjugate was S‐(5‐acetylimino‐4‐methyl‐Δ2‐1,3,4‐thiadiazolinyl)cysteine. The reaction with glutathione was not catalyzed by glutathione S‐transferases, but proceeded in the absence of the enzyme. The glutathione conjugate was degraded by bovine ciliary body homogenate to the cysteinylglycine conjugate and then to the cysteine conjugate.

The influences of both high-voltage stress and hygrothermal stress were studied for homojunction and heterojunction crystalline Si photovoltaic (PV) modules. In order to separately access the influence of these stresses, these PV modules were subjected to sequential tests with hygrothermal stress and high-voltage stress for various stress durations of each test. It was found that for p-type homojunction crystalline Si PV modules hygrothermal stress applied in advance considerably enhances potential-induced degradation (PID) by high-voltage stress. High-voltage stress applied in advance also accelerates finger-electrode degradation by hygrothermal stress. It was also clarified that hygrothermal stress for short duration applied in advance considerably enhances PID by high-voltage stress for n-type heterojunction crystalline Si PV modules. The possible mechanisms for these accelerated degradation phenomena by the combined stresses are presented.

We investigated the influence of backsheet materials on potential-induced degradation (PID) in n-type crystalline-silicon (c-Si) photovoltaic (PV) cell modules. Silicon heterojunction PV cell modules and rear-emitter n-type c-Si PV cell modules were fabricated by using aluminum backsheets composed of poly ethylene terephthalate (PET)/aluminum/PET as well as typical backsheets. PID tests of the modules were performed by applying a negative bias in a dry environment (<2% relative humidity). Regardless of the types of cells, the modules with the aluminum backsheets showed smaller degradation. This indicates that aluminum backsheets reduce PID effects, and to alter backsheets may be a potential measure to reduce PID.

Quantitative evaluations of output power and the development of a technique for countermeasures against volcanic ash fall are required in a volcanic ash fall environment. In this study, in order to clarify the effect of volcanic ash fall on the output power of photovoltaic (PV) modules and the effects of the hydrophilic coating on PV module cover glass, we evaluated the output power characteristics of PV modules by an artificial test. The hydrophilic coating was carried out using an inorganic material and formed an antisoiling layer on the PV module surface. The output power characteristics of PV modules were measured using a solar simulator. The superiority of the hydrophilically coated cover glass was found between the setting angles of 40 to 60deg and the most remarkable in the vicinity of 45deg. Moreover, it was confirmed that the superiority of the hydrophilically coated cover glass increases with an increase in the amount of ash fall.

A novel, nondestructive low-cost detection method for acetic acid distribution in a photovoltaic (PV) module during the damp heat (DH) test based on reflectance changes of tin film sensors is proposed and demonstrated. The sensor consists of a tin film evaporated on a glass substrate. Nineteen sensors and one gold film are laminated in the PV module, and the DH test was performed at 85 degC and 85% relative humidity for 7203 h. The time range of measurement can be controlled between 2000 to 6000 h by adjusting the tin film initial thickness from 70 to 160 nm.

The sequential combination test for photovoltaic modules is effective for accelerating degradation to shorten the test time and for reproducing degradation phenomena observed in modules exposed outdoors for a long time. The damp-heat (DH) test, thermal-cycle (TC) test, humidity-freeze (HF) test or dynamic mechanical load (DML) test is combined for the test modules. It was confirmed that chemical corrosion degradation or physical mechanical degradation is reproduced by the combination of the above tests. Cracks on the back sheet and delamination, often observed upon outdoor exposure, were well reproduced by the combination of DH and TC tests and TC and HF tests, respectively. Sequential DH and TC tests and DML and TC tests accelerated the degradation. These sequential tests are expected to be effective in reducing the required time of indoor testing for ensuring long-term reliability.