Lithium inhibits function of voltage-dependent sodium channels and catecholamine secretion independent of glycogen synthase kinase-3 in adrenal chromaffin cells

Lithium has been proven to be effective in the therapy of bipolar disorder, but its mechanism of pharmacological action is not clearly defined. We examined the effects of lithium on voltage-dependent Na(+) channels, nicotinic acetylcholine receptors, and voltage-dependent Ca(2+) channels, as well as catecholamine secretion in cultured bovine adrenal chromaffin cells. Lithium chloride (LiCl) reduced veratridine-induced (22)Na(+) influx in a concentration-dependent manner, even in the presence of ouabain, an inhibitor of Na(+), K(+)-ATPase. Glycogen synthase kinase-3 (GSK-3) inhibitors (SB216763, SB415286 or the GSK-3 inhibitor IX) did not affect veratridine-induced (22)Na(+) influx, as well as inhibitory effect of LiCl on veratridine-induced (22)Na(+) influx. Enhancement of veratridine (site 2 toxin)-induced (22)Na(+) influx caused by alpha-scorpion venom (site 3 toxin), beta-scorpion venom (site 4 toxin), or Ptychodiscus brevis toxin-3 (site 5 toxin), still occurred in the presence of LiCl in the same manner as in the control cells. LiCl also reduced veratridine-induced (45)Ca(2+) influx and catecholamine secretion. In contrast, LiCl (< or = 30 mM) had no effect on nicotine-induced (22)Na(+) influx, (45)Ca(2+) influx and catecholamine secretion, as well as on high K(+)-induced (45)Ca(2+) influx and catecholamine secretion. Chronic treatment with LiCl at 100mM (but not at < or = 30 mM) significantly reduced cell viability in a time-dependent manner. These results suggest that lithium selectively inhibits Na(+) influx thorough Na(+) channels and subsequent Ca(2+) influx and catecholamine secretion, independent of GSK-3 inhibition.     

Transient keratectasia caused by intraocular pressure elevation after laser in situ keratomileusis

Transient keratectasia developed in association with a marked intraocular pressure (IOP) elevation in a 26-year-old man who had laser in situ keratomileusis (LASIK) for myopia of -9.0 diopters. The keratectasia subsided promptly after the IOP was normalized by an intravenous administration of mannitol. Keratectasia did not recur. Intraocular pressure elevation can cause keratectasia in a structurally compromised cornea after LASIK.     

The prevalence of strabismus and amblyopia in Japanese elementary school children

BACKGROUND: The purpose of this study is to elucidate the prevalence of strabismus and amblyopia in a large population of Japanese elementary school children, from Grade 1 to Grade 6, ages ranging from 6 to 12 years. The School Health Law requires that all pupils in Grade 1 to Grade 6 be examined for vision and eye problems. Visual acuity testing is done by school teachers and eye disease screening by school ophthalmologists. Pupils with suspected ocular diseases are further examined by extramural ophthalmologists and the results reported back to the schools. The schools then summarize and send uncorrected visual acuity and ocular disease incidence, together with other health statistics, to the municipal education committees. The data are forwarded to the Prefecture Governments and finally submitted to the Education Ministry of the Central Government. Both the Prefecture Governments and the Education Ministry publicize the school health statistics on their websites. The prevalence of strabismus and amblyopia remains unknown from these data because both diagnoses are included under the heading, eye diseases. METHODS: Questionnaires asking about the numbers of children with different types of strabismus and amblyopia were sent to all elementary schools in Okayama Prefecture and the results were summarized. RESULTS: The number of children covered by the return of questionnaires was 86,531 (76.4%) of 113,254 total pupils in Grade 1 to Grade 6 in Okayama Prefecture in the year 2003. The total numbers of children with strabismus and amblyopia were 1,112 (1.28%) and 125 (0.14%), respectively. The numbers of children with any type of exotropia and any type of esotropia were 602 (0.69%) and 245 (0.28%), respectively. The major types of strabismus and amblyopia were intermittent exotropia in 109 children (0.12%), accommodative esotropia in 19 children (0.02%), anisometropic amblyopia in 23 children (0.03%), and ametropic amblyopia in 12 children (0.01%). The number of children with strabismus of unknown type was 245 (0.28%) while the number of children with amblyopia of unknown type was 81 (0.09%). CONCLUSIONS: The prevalence rates of strabismus and amblyopia in this population of Japanese elementary school children were lower than those reported in Western countries. The exotropia/esotropia ratio were increased in comparison with past studies in Japan. The school eye doctors need to be more diligent in identifying and diagnosing various types of strabismus and amblyopia in order to contribute to the school vision screening program already in place in Japan     

Quercetin-induced PC12 cell death accompanied by caspase-mediated DNA fragmentation

Flavonoids have been reported to be potent antioxidants and beneficial in oxidative stress related diseases. Quercetin, a major flavonoid in food, deserves much attention because of its antioxidative activity. However, the actions of flavonoids including quercetin are complex and paradoxical. Quercetin caused apoptosis and/or cell death in various cells including cancer cells and normal cells. In this study, we investigated the effects of quercetin with or without hydrogen peroxide (H2O2) on cell death of PC12 cells, a neuronal cell line. We showed that quercetin at 10-30 microM alone caused cell death accompanied by caspase-mediated DNA fragmentation in undifferentiated PC12 cells. Quercetin did not inhibit and rather enhanced 0.1 mM H2O2-induced cell death. The toxic effect of quercetin was not inhibited by antioxidants such as N-acetylcysteine and GSH, although H2O2-induced cell death was inhibited by the antioxidants. Quercetin-induced cell death was reduced by 2 h treatment with nerve growth factor and serum. In addition, quercetin caused cell death in differentiated PC12 cells that were cultured with nerve growth factor for 6 d. Genistein, a soy isoflavone that has the pro-apoptotic activity, also caused cell death with DNA fragmentation. Further evaluation of the potential of dietary flavonoids as neuroprotective reagents is needed.     

hOGG1 Ser326Cys polymorphism and risk of hepatocellular carcinoma among Japanese

BACKGROUND: The Ser326Cys polymorphism in human oxoguanine glycosylase 1 (hOGG1), which is involved in the repair of 8-hydroxy-2-deoxyguanine in oxidatively damaged DNA, has been associated with susceptibility to certain cancers, but has not been examined in causation of hepatocellular carcinoma (HCC). METHODS: We conducted a case-control study to investigate whether this polymorphism was related to HCC risk with any interaction with alcohol consumption and cigarette smoking. Genotyping was performed by a polymerase chain reaction with confronting two-pair primers among 209 newly diagnosed HCC cases, 275 hospital controls, and 381 patients with chronic liver disease (CLD) without HCC. RESULTS: Overall, the hOGG1 genotype was not significantly associated with HCC; adjusted odds ratios (and 95% confidence intervals) for the Ser/Cys and Cys/Cys genotypes compared with the Ser/Ser genotype were 0.79 (0.35-1.79) and 0.48 (0.18-1.27) against hospital controls, and 1.51 (0.96-3.37) and 0.86 (0.50-1.47) against CLD patients. We could not detect any significant gene-alcohol interaction (p = 0.95 or 0.16) or gene-smoking interaction (p = 0.70 or 0.69). CONCLUSIONS: These results suggest that the hOGG1 Ser326Cys polymorphism may not play a major role as an independent factor in hepatocarcinogenesis.     

Possible role of interleukin-6 in PC12 cell death induced by MPP+ and tetrahydroisoquinoline

Interleukin (IL)-6 has been shown to protect neuronal cells from cell death induced by various stimulants. Although neuronal cells including PC12 cells were shown to produce IL-6, little is known about the effects of dopaminergic neurotoxins, 1,2,3,4-tetrahydroisoquinoline (TIQ) and 1-methyl-4-phenylpyridinium ion (MPP(+)), on IL-6 expression in PC12 cells. In the present study, we investigated the role of IL-6 in the TIQ- and MPP(+)-induced cell death in PC12 cells. Treatment with 3.2 mM TIQ for 24 h caused a delayed cell death (lactate dehydrogenase (LDH) leakage and nuclear DNA fragmentation) markedly 72 h after the addition. Addition of 0.4 mM MPP(+) caused LDH leakage and nuclear DNA fragmentation 24 h after the addition. The cell death induced by MPP(+) was inhibited by an inhibitor of caspases, z-Val-Ala-Asp(OMe)-fluoromethylketone. The cell death induced by TIQ or MPP(+) was inhibited by nerve growth factor and 10% serum and significantly enhanced by the treatment with anti-IL-6 antibody. Both neurotoxins decreased the IL-6 mRNA level in PC12 cells without changing the other tested mRNA levels (IL-1 alpha, beta-actin, etc.). These findings suggest that dopaminergic neurotoxins cause cell death in PC12 cells at least partially by changing IL-6 expression.     

The combined effects of multiple chemotherapeutic agents for malignant glioma cells

The prognosis of malignant gliomas remains poor, despite the progress of surgery and radiotherapy. Chemotherapy has been shown to prolong an overall survival, but the benefits are still small. To overcome this situation, the optimal regimen of antineoplastic agents is required. In the present study, we investigated the effect of the association of five chemotherapeutic drugs, including ACNU, CBDCA, CDDP, VCR, and VP-16, on cell survival of U87, YKG1, A172, and U251 human glioma cell lines, using median-effect analysis. A synergistic effect was obtained by treatment involving the association of VP-16 with ACNU or CDDP among the combinations of two drugs, and the association of ACNU, CBDCA, and VP-16 in the combination of three drugs. This preclinical screening using median-effect analysis supports the design of clinical trials by indicating more effective combinations of antineoplastic agents for malignant gliomas.     

Superior vena cava syndrome caused by supraclavicular lymph node metastasis of renal cell carcinoma

A 65-year-old woman presented with gross hematuria in February 1997. Left renal tumor was revealed and radical nephrectomy was performed. Pathological examination revealed papillary renal cell carcinoma, pT3aN1M1 (ipsilateral adrenal gland). Interferon-α was administered for 1 year. Two years after the nephrectomy, metastasis to the left supraclavicular lymph node appeared. Seven years after the nephrectomy, the metastatic tumor invaded the brachiocephalic vein and extended to the superior vena cava (SVC), compatible with SVC syndrome. Although interferon-α and external-beam radiotherapy was performed, she died in February 2005. Autopsy revealed a left supraclavicular lymph node metastasis invading the thyroid gland, mediastinum, and brachiocephalic vein. The tumor thrombus descended via the SVC into the right atrium. The right lung artery was obstructed by tumor thrombus. There were no visceral metastases and no local recurrence.     

Involvement of different human glutathione transferase isoforms in the glutathione conjugation of reactive metabolites of troglitazone

Null mutation of glutathione transferase (GST) M1 and GSTT1 was reported to correlate statistically with an abnormal increase in the plasma levels of alanine aminotransferase or aspartate aminotransferase caused by troglitazone in diabetic patients (Clin Pharmacol Ther, 73:435-455, 2003). This clinical evidence leads to the hypothesis that GSH conjugation catalyzed by GSTT1 and GSTM1 has a role in the elimination of reactive metabolites of troglitazone. However, the contribution of GST isoforms expressed in human liver to the detoxification of reactive metabolites of troglitazone has not yet been clarified. We investigated the involvement of human GST isoforms in the GSH conjugation of reactive metabolites of troglitazone using recombinant GST enzymes. Five reported GSH conjugates of reactive metabolites were produced from troglitazone after incubation with liver microsomes, NADPH, and GSH in a GSH concentration-dependent manner. Addition of human recombinant GSTA1, GSTA2, GSTM1, or GSTP1 protein to the incubation mixture further increased the GSH conjugates. However, the addition of GSTT1 did not show any catalytic effect. It is of interest that one of the reactive metabolites with a quinone structure was predominantly conjugated with GSH by GSTM1. Thus, we demonstrated that the GST isoforms contributed differently to the GSH conjugation of individual reactive metabolites of troglitazone, and GSTM1 is the most important GST isoform in the GSH conjugation of a specific reactive metabolite produced from the cytotoxic, quinone-form metabolite of troglitazone.     

Drug-induced idiosyncratic hepatotoxicity: prevention strategy developed after the troglitazone case

Troglitazone induced an idiosyncratic, hepatocellular injury-type hepatotoxicity in humans. Statistically, double null genotype of glutathione S-transferase isoforms, GSTT1 and GSTM1, was a risk factor, indicating a low activity of the susceptible patients in scavenging chemically reactive metabolites. CYP3A4 and CYP2C8 were involved in the metabolic activation and CYP3A4 was inducible by repeated administrations of troglitazone. The genotype analysis, however, indicated that the metabolic idiosyncrasy resides in the degradation of but not in the production of the toxic metabolites of troglitazone. Antibody against hepatic aldolase B was detected in the case patients, suggesting involvement of immune reaction in the toxic mechanism. Troglitazone induced apoptotic cell death in human hepatocytes at a high concentration, and this property may have served as the immunological danger signal, which is thought to play an important role in activating immune reactions. Hypothesis is proposed in analogy to the virus-induced hepatitis. After the troglitazone-case, pharmaceutical companies implemented screening systems for chemically reactive metabolites at early stage of drug development, taking both the amount of covalent binding to the proteins in vitro and the assumed clinical dose level into consideration. At the post-marketing stage, gene analyses of the case patients, if any, to find pharmacogenetic biomarkers could be a powerful tool for contraindicating to the risky patients.