Dotinurad: a clinical pharmacokinetic study of a novel, selective urate reabsorption inhibitor in subjects with hepatic impairment

BACKGROUND

Dotinurad is a novel, selective urate reabsorption inhibitor, which reduces serum uric acid levels by inhibiting the urate transporter 1 (URAT1). We compared the pharmacokinetics (PK), pharmacodynamics (PD), and safety of dotinurad in subjects with hepatic impairment and normal hepatic function.

METHODS

This was a multicenter, open-label, single dose study. A total of 24 subjects were divided into four groups: the normal hepatic function group and the mild, moderate, and severe hepatic impairment groups. The primary endpoints were changes in plasma dotinurad levels and PK parameters.

RESULTS

The geometric mean ratio of the maximum plasma concentration (Cmax) [two-sided 90% confidence interval (CI)] of dotinurad in in the mild, moderate, and severe hepatic impairment groups relative to that in the normal hepatic function group was 0.840 (0.674-1.047), 0.798 (0.653-0.976), and 0.747 (0.570-0.979), respectively, showing a lower Cmax in the moderate and severe hepatic impairment groups. Following adjustment for body weight, only the moderate hepatic impairment group had a lower Cmax than the normal hepatic function group. No meaningful differences in other PK parameters were observed between the groups. Regarding the PD of dotinurad, the changes in serum uric acid levels after dosing were similar in all groups. As for safety, no noteworthy concerns were raised in relation to any group.

CONCLUSION

The study revealed no clinically meaningful influence of hepatic impairment on the PK, PD, or safety of dotinurad. These findings indicate possibility that dotinurad can be used without dose adjustment in patients with hepatic impairment.

A clinical pharmacology study of the novel, selective urate reabsorption inhibitor dotinurad in outpatients

BACKGROUND

Dotinurad is a novel, selective urate reabsorption inhibitor (SURI), which reduces serum uric acid levels by selective inhibition of the urate transporter 1 (URAT1). The Japanese guideline for the management of hyperuricemia and gout recommends that drug selection should be based on classification of hyperuricemia as a fundamental principle. However, there may be some cases where this principle is not observed. We investigated the pharmacodynamics and safety of dotinurad in outpatients with uric acid overproduction or uric acid underexcretion type.

METHODS

This was a multicenter, open-label, forced titration study. Patients were classified as uric acid overproduction or underexcretion type. Study treatment was initiated at 0.5 mg/day, followed by dose titration to the estimated maximum dose of 4 mg/day over 14 weeks. The primary endpoint was urinary uric acid excretion at each 24-h urine collection.

RESULTS

A total of 26 hyperuricemic patients with or without gout were enrolled in the study and assigned to the uric acid overproduction group (overproduction group) or the uric acid underexcretion group (underexcretion group). Although urinary uric acid excretion, the primary endpoint, tended to be slightly greater in the overproduction group, no notable difference was noted between the two hyperuricemic types. Neither type had noteworthy safety concerns associated with dotinurad.

CONCLUSION

The results of the study demonstrated no relevant differences between the hyperuricemic types in terms of pharmacodynamic action and safety of dotinurad.

A non-inferiority study of the novel selective urate reabsorption inhibitor dotinurad versus febuxostat in hyperuricemic patients with or without gout

Background

Dotinurad is a novel, selective urate reabsorption inhibitor, which reduces serum uric acid levels by selective inhibition of the urate transporter 1. We evaluated the efficacy and safety of dotinurad versus febuxostat, a widely used drug in Japan, in hyperuricemic Japanese patients with or without gout.

Methods

This was a multicenter, randomized, double-blind, active-controlled, parallel-group, forced-titration study in hyperuricemic patients. Study treatment in the dotinurad and febuxostat groups was initiated at 0.5 and 10 mg/day, followed by dose titration to 2 and 40 mg/day, respectively, over 14 weeks. The primary endpoint was the percent change in serum uric acid level from the baseline to the final visit.

Results

A total of 203 hyperuricemic patients with or without gout were enrolled in the study and randomized to receive dotinurad or febuxostat. The percent change in serum uric acid level from the baseline to the final visit was 41.82% in the dotinurad group and 44.00% in the febuxostat group. The mean difference was − 2.17% (two-sided 95% confidence interval − 5.26% to 0.92%). The lower limit of the interval was above the non-inferiority margin (− 10%), demonstrating the non-inferiority of dotinurad to febuxostat. The profiles of adverse events and adverse drug reactions raised no noteworthy safety concerns in either group.

Conclusion

The non-inferiority of dotinurad to febuxostat in terms of serum uric acid lowering effect was confirmed. No noteworthy safety concerns arose.

Precision measurement of neutrino oscillation parameters with KamLAND

The KamLAND experiment has determined a precise value for the neutrino oscillation parameter Deltam21(2) and stringent constraints on theta12. The exposure to nuclear reactor antineutrinos is increased almost fourfold over previous results to 2.44 x 10(32) proton yr due to longer livetime and an enlarged fiducial volume. An undistorted reactor nu[over]e energy spectrum is now rejected at >5sigma. Analysis of the reactor spectrum above the inverse beta decay energy threshold, and including geoneutrinos, gives a best fit at Deltam21(2)=7.58(-0.13)(+0.14)(stat) -0.15+0.15(syst) x 10(-5) eV2 and tan2theta12=0.56(-0.07)+0.10(stat) -0.06+0.10(syst). Local Deltachi2 minima at higher and lower Deltam21(2) are disfavored at >4sigma. Combining with solar neutrino data, we obtain Deltam21(2)=7.59(-0.21)+0.21 x 10(-5) eV2 and tan2theta12=0.47(-0.05)+0.06.

Maturational alterations of peripheral T cell subsets and cytokine gene expression in 22q11.2 deletion syndrome

Chromosome 22q11.2 deletion syndrome is a common disorder characterized by thymic hypoplasia, conotruncal cardiac defect and hypoparathyroidism. Patients have a risk of infections and autoimmunity associated with T lymphocytopenia. To assess the immunological constitution of patients, the numerical changes and cytokine profile of circulating T cells were analysed by flow cytometry and real-time polymerase chain reaction (PCR). CD3+, CD4+, T cell receptor (TCR)alphabeta+ or CD8alphaalpha+ cell counts were lower, and CD56+ cell counts were higher in patients than in controls during the period from birth to adulthood. The ageing decline of CD3+ or CD4+ cell counts was slower in patients than in controls. The proportion of CD8alphaalpha+ cells increased in controls, and the slope index was larger than in patients. On the other hand, both the number and proportion of Valpha24+ cells increased in patients, and the slope indexes tended to be larger than in controls. The positive correlation of the number of T cells with CD8alphaalpha+ cells was observed only in patients, and that with Valpha24+ cells was seen only in controls. No gene expression levels of interferon (IFN)-gamma, interleukin (IL)-10, transforming growth factor (TGF)-beta, cytotoxic T lymphocyte antigen 4 (CTLA4) or forkhead box p3 (Foxp3) in T cells differed between patients and controls. There was no significant association between the lymphocyte subsets or gene expression levels and clinical phenotype including the types of cardiac disease, hypocalcaemia and frequency of infection. These results indicated that T-lymphocytopenia in 22q11.2 deletion patients became less severe with age under the altered composition of minor subsets. The balanced cytokine profile in the limited T cell pool may represent a T cell homeostasis in thymic deficiency syndrome.

Search for the invisible decay of neutrons with KamLAND

The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments.

Experimental investigation of geologically produced antineutrinos with KamLAND

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

Identification of novel MUNC13-4 mutations in familial haemophagocytic lymphohistiocytosis and functional analysis of MUNC13-4-deficient cytotoxic T lymphocytes

BACKGROUND

Familial haemophagocytic lymphohistiocytosis (FHL) has an autosomal recessive mode of inheritance and consists of at least three subtypes. FHL2 subtype with perforin (PRF1) mutation accounts for 30% of all FHL cases, while FHL with MUNC13-4 mutation was recently identified and designated as FHL3 subtype.

OBJECTIVE

To examine MUNC13-4 mutations and the cytotoxic function of MUNC13-4 deficient T lymphocytes in Japanese FHL patients

METHODS

Mutations of MUNC13-4 and the cytotoxicity of MUNC13-4-deficient cytotoxic T lymphocytes (CTL) were analysed in 16 Japanese families with non-FHL2 subtype.

RESULTS

Five new mutations of the MUNC13-4 gene were identified in six families. The mutations were in the introns 4, 9, and 18, and exons 8 and 19. Two families had homozygous mutations, while the remaining four had compound heterozygous mutations. Cytotoxicity of MUNC13-4 deficient CTL was low compared with control CTL, but was still present. Clinically, the onset of disease tended to occur late; moreover, natural killer cell activity was not deficient in some FHL3 patients.

CONCLUSIONS

MUNC13-4 mutations play a role in the development of FHL3 through a defective cytotoxic pathway.

Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion

We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

High sensitivity search for nu;e's from the sun and other sources at KamLAND

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for nu;(e)'s in the energy range 8.3<E(nu;(e))<14.8 MeV. No candidates were found for an expected background of 1.1+/-0.4 events. This result can be used to obtain a limit on nu;(e) fluxes of any origin. Assuming that all nu;(e) flux has its origin in the Sun and has the characteristic 8B solar nu(e) energy spectrum, we obtain an upper limit of 3.7 x 10(2) cm(-2) s(-1) (90% C.L.) on the nu;(e) flux. We interpret this limit, corresponding to 2.8 x 10(-4) of the standard solar model 8B nu(e) flux, in the framework of spin-flavor precession and neutrino decay models.

Asthma-like attacks resulting from the isolated congenital left pulmonary artery agenesis with right main bronchus stenosis

A 5-year-old girl with isolated congenital left pulmonary artery agenesis suffered from recurrent attacks of dyspnea and right-sided pneumonia due to the stenosis of the right main bronchus. The division of ligamentum of the ductus arteriosus and suspension of the right pulmonary artery resulted in the disappearance of symptoms. It is notable that the compression of contralateral bronchus by the remaining pulmonary artery can cause respiratory symptoms in patients with isolated unilateral pulmonary artery agenesis.

First results from KamLAND: evidence for reactor antineutrino disappearance

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

Pituitary adenylate cyclase-activating polypeptide produces a phase shift associated with induction of mPer expression in the mouse suprachiasmatic nucleus

The main mammalian circadian pacemaker is located in the suprachiasmatic nucleus of the hypothalamus. Clock genes such as the mouse Period gene (mPer) play a role in this core clock mechanism in the mouse. With brief light exposure during the subjective night, the photic information, which is conveyed directly to the suprachiasmatic nucleus via the retinohypothalamic tract, results in mPer1 and mPer2 expression in the suprachiasmatic nucleus. Glutamate and pituitary adenylate cyclase-activating polypeptide (PACAP) are co-stored in the retinohypothalamic tract. Recent studies have suggested that not only glutamate but also PACAP are key players in the phase shift that occurs during subject night; however, research demonstrating a direct association between the PACAP-induced phase shift and mPer gene expression has yet to be conducted. In the present study, PACAP (200 pmol) injected into the lateral ventricle during subjective night (circadian time 16; circadian time 12, onset of locomotor activity) caused a moderate phase delay associated with moderate expression of mPer1 and only slight expression of mPer2 in the mouse suprachiasmatic nucleus. PACAP-induced mPer1 expression was also observed in the paraventricular nucleus and periventricular area of the hypothalamus. (+)MK-801 (0.5 mg/kg), an N-methyl-D-aspartate (NMDA) receptor antagonist, suppressed both the PACAP-induced phase delay and mPer1 expression. From these results we suggest that PACAP induces phase delays in the mouse circadian rhythm in association with an increase of mPer expression in the suprachiasmatic nucleus via the activation of NMDA receptors.

Influence of oral adsorbent AST-120 on anticonvulsive effect of zonisamide in rats

The influence of oral adsorbent AST-120 (Kremezin) on the anticonvulsive effect and pharmacokinetics of zonisamide was investigated. Oral administration of zonisamide (50 mg/kg) blocked the appearance of the tonic extension induced by maximal electroshock seizure. This effect of zonisamide was inhibited by the oral coadministration of AST-120 (5 g/kg). In pharmacokinetics study, the serum zonisamide concentration after coadministration of zonisamide and AST-120 was significantly lower than that of single administration of zonisamide. However, the anticonvulsive effect of zonisamide was not affected by the administration of AST-120 1.5 h after zonisamide administration. In this condition, the serum zonisamide concentration was not changed. In the in vitro study, AST-120 completely adsorbed zonisamide. These findings suggest that when AST-120 is administered concurrently with zonisamide, a significant inhibition of the anticonvulsive effect of zonisamide occurs, and the decrease in serum zonisamide concentration by the adsorption effect of AST-120 is related to this phenomenon.

Serum phenytoin concentration and IgG antibody titre to periodontal bacteria in patients with phenytoin-induced gingival overgrowth

Epileptic patients taking phenytoin with gingival-overgrowth and those without gingival-overgrowth were compared for daily drug dose, plasma total phenytoin concentration, plasma free-phenytoin concentration and serum IgG antibody titre against 13 periodontal bacteria. Significantly higher daily drug dose was noted in patients with gingival overgrowth (P < 0.05) when compared with those without overgrowth. In addition, both total and free forms of plasma phenytoin concentration were significantly higher in sera of patients with gingival growth than of those without overgrowth (P < 0.01). Strong positive correlation was found between daily drug dose and serum phenytoin concentration in patients with gingival overgrowth, while weak correlation was found in patients without gingival overgrowth, suggesting a difference in drug metabolism in these two groups. However, no differences were found in serum IgG antibody titres to 13 periodontal bacteria examined between two groups. These results suggest that metabolic ability of phenytoin is one of the factors for developing gingival overgrowth, and that periodontal infection may not be a primary causative factor for gingival overgrowth but act as an additive factor which increase tissue mass for this unwanted side effect.

An infant with precursor natural killer (NK) cell leukemia successfully treated with an unrelated cord blood transplantation

Here we report a case with precursor natural killer (NK) cell leukemia successfully treated with an unrelated cord blood transplantation. A 7-month-old Japanese boy was diagnosed to have NK cell leukemia based on the existence of abnormal cells in the bone marrow with the phenotype of CD3(-) /CD4(+) /CD7(-) /CD8(-) /CD16(-) /CD33(+) /CD34(-) /CD56(+) /HLA-DR(+) /NKB1(+) / CD94(+). The leukemic cells showed few azurophilic granules in the cytoplasm and weak cytotoxic activity. Although he presented with a huge mass occupying the bilateral paranasal sinuses and hepatosplenomegaly, he achieved complete remission by the conventional chemotherapeutic regimen for acute myelogenous leukemia, followed by an unrelated cord blood transplantation. He has remained in complete remission for 14 months posttransplant. To our knowledge, this is the youngest reported case with precursor NK cell leukemia; cord blood transplantation may thus be the treatment of choice for this disease.

Myoepithelioma of the lacrimal gland: report of a case with potentially malignant transformation

Myoepithelioma of the lacrimal gland is extremely rare and only four cases, one of which was malignant, have been reported in detail. The present report describes a case of lacrimal gland myoepithelioma in a Japanese male with histological features suggestive of potentially malignant transformation. The excised tumor consisted of two components, a central nodular component and a peripheral component surrounding the former. These components were separated by a fibrous tissue. Microscopically, both components were comprised almost entirely of spindle-shaped cells, but with some epithelioid cells containing glycogen granules. Extracellular spaces in the peripheral component were filled with eosinophilic materials with the occasional crystalloid structures, which were immunoreactive for collagen type I. Neoplastic cells were immunoreactive focally for vimentin and S-100, but negative for cytokeratins, epithelial membrane antigen, muscle actin, smooth muscle actin, desmin, myosin, and glial fibrillary acidic protein. The neoplastic cells in the central component showed nuclear pleomorphism and atypia with a higher frequency of mitotic figures, and higher labelings of proliferation markers than those in the peripheral component. Neither invasion, necrosis, nor hemorrhage was observed in the tumor. From these findings we proposed a diagnosis of potentially malignant myoepithelioma.

Anti- and pro-oxidative effects of flavonoids on metal-induced lipid hydroperoxide-dependent lipid peroxidation in cultured hepatocytes loaded with alpha-linolenic acid

Lipid hydroperoxide (LOOH)-dependent lipid peroxidation was induced in alpha-linolenic acid (LNA)-loaded hepatocytes by adding Fe, Cu, V, or Cd ions at concentrations from 20 to 500 microM. The effects of structurally related flavonoids at concentrations from 10 to 500 microM on the lipid peroxidation were examined. The results with regard to each flavonoid subclass are as follows: (i) Flavonols such as myricetin, quercetin, fisetin, and kaempferol, but not morin, showed dose-dependent antioxidative activity against metal-induced lipid peroxidation at all metal concentrations. Myricetin, quercetin, and fisetin were the most effective antioxidants, although their efficacies depended on the metal ion. Kaempferol and morin had antioxidative activity equal to the other flavonols in the presence of Cu ions, but were much less effective for the other three metal ions. (ii) Flavones, luteolin, apigenin, and chrysin were antioxidative at low Fe concentrations, but were pro-oxidative at high Fe concentrations. Luteolin exhibited antioxidative activity similar to that of catechol-containing flavonols in the presence of the other three metal ions. Apigenin and chrysin also acted as pro-oxidants with V or with all metal ions, respectively. (iii) Taxifolin, a flavanone, also showed both anti- and prooxidative activity, depending on Fe concentrations, but with other metal showed only antioxidative activity ions. (iv) Epigallocatechin, a flavanol, was antioxidative with all metal ions, and its activity was similar to that of catechol-containing flavonols. The various effects of flavonoids on metal-induced lipid peroxidation in LNA-loaded hepatocytes is discussed with regard to the change in redox potential of flavonoid-metal complexes.

Mexiletine-sensitive membrane electrode for medical application

Response characteristics of mexiletine-sensitive membrane electrodes based on crown ether and ion-exchanger were examined in a physiological saline in order to find an electrode suitable for determining concentrations of this drug under physiological conditions. Among various crown ethers screened, 4',4"(5")-di-tert-butyldicyclohexano-18-crown6 showed the highest sensitivity to mexiletine in physiological saline containing 0.15 M NaCl and 5 mM 4-(2-hydroxyethyl)-2-piperazineethanesulfonic acid (Hepes) NaOH (pH 7.4). However, the detection limit of 30 microM was 10 times higher than that of 3 microM observed with the electrode based on an ion-exchanger, sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate. Having high selectivity against inorganic cations such as Na+ or K+, the electrode using the ion-exchanger enabled us to determine the level of mexiletine in saliva, the monitoring of which is quite effective for controlling the dose of this drug noninvasively. The mexiletine concentrations determined with the mexiletine electrode compared favourably with those determined by high-performance liquid chromatography which requires an additional procedure to extract mexiletine from saliva.

Determination of plasma phenobarbital concentration by high-performance liquid chromatography in rat offspring

Plasma phenobarbital (PB) concentrations in rat offspring were determined using a 9 microl capillary by high-performance liquid chromatography (HPLC). Capillary plasma which was put into a Bond Elut cartridge column by using 1 ml of 0.01 M KH2PO4 was applied to the column with 50 microl of 2 microg/ml of acetanilide (internal standard, I.S.). After washing the column, PB and I.S. were eluted with methanol and injected into the HPLC system. There were excellent linear correlation between the amount of PB and length of the capillary at three different concentrations. Calibration for PB was linear in the range of 0-50 microg/ml. The coefficients of variation were 3.4-5.0% and 5.9-7.5% in the within-day and between-day assays, respectively. The extraction recovery rates were 87.5-105.4%. By this method, it was possible to measure plasma PB concentrations in rat offspring without killing. These results suggested that this method is very useful to determine the plasma PB concentration derived from mother's milk in newborn rats.

Lipid peroxidation induced by adriamycin in linolenic acid-loaded cultured hepatocytes

Addition of more than 10 microM of adriamycin to cultured rat hepatocytes loaded with alpha-linolenic acid (linolenic acid-loaded hepatocytes) caused marked lipid peroxidation as measured by an accumulation of malondialdehyde during a 9 hr incubation. After addition of 50 microM of adriamycin to linolenic acid-loaded hepatocytes, malondialdehyde accumulation significantly increased at 3 hr, followed by cellular reduced glutathione decrease and lactate dehydrogenase leakage after 6 hr. Inhibition of adriamycin-induced lipid peroxidation by addition of N,N'-diphenyl-p-phenylenediamine or alpha-tocopherol, both lipid radical scavengers, or deferoxamine, which is a Fe ion chelator, prevented both glutathione decrease and lactate dehydrogenase leakage, indicating that lipid peroxidation caused cellular damage to linolenic acid-loaded hepatocytes exposed to adriamycin. The effect of SKF 525-A, which is a cytochrome P450 inhibitor, on adriamycin-induced lipid peroxidation and on 7-ethoxycoumarin O-deethylase activity was determined by 6 hr incubation of linolenic acid-loaded cells. Addition of SKF 525-A suppressed adriamycin-induced lipid peroxidation comparably with its 7-ethoxy-coumarin 0-deethylase inhibitory activity. These results suggest that cytochrome P450 contributes to the one-electron bioreduction of adriamycin into its semiquinone radical in rat hepatocytes.

Steady-state serum concentrations of carbamazepine and valproic acid in obese and lean patients with epilepsy

Steady-state serum concentrations of carbamazepine (CBZ) and valproic acid (VPA) were investigated in normal weight (body mass index; BMI 20 to 25), lean (smaller than 20 BMI) and moderately obese subjects (greater than 25 BMI) who received either 400 mg/day of CBZ or 800 mg/day of VPA. The CBZ serum concentration in lean subjects was significantly higher than that in normal weight subjects. However, no significant differences in VPA serum concentration were found between the three groups. The CBZ serum concentration decreased with increases in total body weight, and the VPA serum concentration decreased with increases in ideal body weight. However, both serum concentrations were not correlated with BMI. These results suggest that VPA doses should be calculated using ideal body weight and that degree of obesity may affect CBZ serum concentration rather than VPA serum concentration.

Effect of potassium sorbate on cellular GSH level and lipid peroxidation in cultured rat hepatocytes

Change in cellular reduced glutathione (GSH) level was examined after the addition of 1-10 mM potassium sorbate (SA-K) to cultured rat hepatocytes. The cellular GSH content was decreased to the lowest level at 6 h after the addition of SA-K, and then gradually returned to the normal level except for hepatocytes exposed to 10 mM SA-K. Although the decrease in GSH level was not associated with lactate dehydrogenase (LDH) leakage in hepatocytes exposed to SA-K up to the concentration of 5 mM, cell injury was caused in cells exposed to 10 mM SA-K. When eicosapentaenoic acid was added in conjunction with various concentrations of SA-K to hepatocytes, peroxidation of the fatty acid was accelerated in parallel with the decrease in cellular GSH level. The enhanced lipid peroxidation in the hepatocytes co-exposed to SA-K and eicosapentaenoic acid (EPA) induced the development of cell injury. These results suggest that hepatocytes exposed to SA-K become susceptible to oxidative stress such as lipid peroxidation.

[Orbital and stomach metastasis from invasive lobular breast carcinoma]

Orbital or ocular metastatic tumors may originate from breast cancer. Few studies have been made regarding their histopathological classification. A 71-year-old female noted a tumor in the right orbital region. She had had bilateral breast cancer 2 years before and gastric cancer 5 months before. Histopathology had shown stage II invasive ductal cancer (scirrhus) in the right breast and stage III invasive lobular cancer in the left. Signet-ring cells were present in the breast and gastric cancers. Biopsy of the right lower eyelid showed poorly differentiated adenocarcinoma with signet-ring cells. Indian file pattern, which is specific for invasive lobular cancer, was also present, suggesting that the orbital tumor had metastatized from the left breast cancer. Genetic analysis of the gastric cancer using polymerase chain reaction showed a mutation at exon 8 of the p53 tumor suppressor gene, indicating the cancer to be metastatic. These results led to the conclusion that invasive lobular cancer of the left breast was the primary lesion for the gastric and orbital metastases. This case also illustrates that signet-ring cells, which are usually seen in gastric cancer, may be present in invasive lobular breast cancer and in orbital metastasis.

Cytotoxicity of food preservatives in cultured rat hepatocytes loaded with linolenic acid

We investigated the ability of eight food preservatives to induce lipid peroxidation in normal and alpha-linolenic acid (LNA)-loaded cultured rat hepatocytes. On the addition of sodium dehydroacetate (DHA-Na), potassium sorbate (SA-K) or thiabendazole (TBZ) to the cell culture, lipid peroxidation, assessed in terms of the production of malondialdehyde (MDA), was induced in LNA-loaded cells, but not in normal cells. At the low concentrations, induction of lipid peroxidation in LNA-loaded cells was highest with TBZ, whereas at high concentrations DHA-Na greatly induced lipid peroxidation. The occurrence of lipid peroxidation in LNA-loaded cells was accompanied by a decrease in cellular GSH levels with the three preservatives and by a decrease in cellular protein-SH levels with DHA-Na and TBZ. Furthermore, cell injury, measured by the release of LDH, was produced in LNA-loaded cells exposed to DHA-Na and SA-K. The addition of TBZ caused substantial cell injury in normal cells, and even greater injury in LNA-loaded cells. The prevention of lipid peroxidation in LNA-loaded hepatocytes by addition of an antioxidant, N,N'-diphenyl-p-phenylenediamine (DPPD) almost completely prevented DHA-Na- and SA-K-induced cell injury, and reduced TBZ-induced cell injury. The addition of diphenyl (DP), o-phenylphenol (OPP) or butyl p-hydroxybenzoate (BHB) caused severe cell injury, in association with a marked decrease in cellular levels of both of GSH and protein-SH in both groups of cells. However, lipid peroxidation was not detectable in either group of cells exposed to these preservatives. Sodium propionate (PA-Na) and sodium benzoate (BA-Na) had little effect on any cytotoxic parameter in either group of cells.

Effects of various antiepileptic drugs on plasma levels of lamotrigine, a novel antiepileptic, in rats

The pharmacokinetics of lamotrigine (LTG) and effects of carbamazepine (CBZ), valproic acid (VPA) and zonisamide (ZNS) on LTG kinetics were investigated in rats. LTG plasma levels were measured by high-performance liquid chromatography (HPLC). A single oral administration of LTG at 2.5-10 mg/kg showed linear disposition kinetics. In the pharmacokinetic parameters of LTG when combined with CBZ, the maximal plasma concentration (Cmax) and the area under the plasma concentration curve (AUC0-36) values were significantly lower and the time to maximal plasma concentration (Tmax) value was significantly higher than those in LTG alone. Furthermore, the Cmax and AUC0-36 values of LTG when pretreated with CBZ for 7 days were significantly lower than those from simultaneous treatment with CBZ. The Cmax and AUC0-36 values of LTG when combined with VPA were significantly lower than those for LTG alone. There was no significant difference in the Tmax or time of elimination half-life (t1/2) values of LTG between simultaneous and pretreatment with VPA. Of the pharmacokinetic parameters of LTG with ZNS combination, the Cmax value of LTG after long-term dosings of ZNS decreased significantly, whereas no significant change in Cmax was observed after the combined single administration of LTG and ZNS. Single and chronic ZNS treatment did not significantly affect the Tmax, t1/2 and AUC0-36 values of LTG. The LTG trough level was significantly reduced by CBZ administration, reached the bottom level at 6 days after starting CBZ administration, and recovered gradually after withdrawal of CBZ. These results suggest that CBZ, VPA and ZNS causes changes in the plasma LTG level. They also suggest that in therapy combining LTG with one of these antiepileptics, especially CBZ, the LTG concentration in plasma should be monitored carefully.

Effects of cigarette smoke inhalation on plasma diltiazem levels in rats

A rapid and sensitive method for the assay of plasma diltiazem was developed using a solid-phase extraction technique followed by high-performance liquid chromatography. The effects of cigarette smoke on plasma levels of orally administered diltiazem was investigated in rats. The animals were exposed to cigarette smoke for 10 min using a Hamburg II smoking machine, immediately after oral administration of diltiazem (10 mg/kg). In the nonsmoking nonrestrained rats, plasma diltiazem levels increased rapidly and reached the maximum (7.1 micrograms/kg) 2 h after administration and decreased gradually thereafter. In the nonsmoking restrained rats, plasma diltiazem levels increased rapidly, but showed almost constant levels between 1 h and 8 h after administration. The maximum level (5.4 micrograms/kg) was shown after 2 h. On the other hand, plasma diltiazem levels in the rats exposed to cigarette smoke reached the maximum (4.3 micrograms/kg) after 4 h. These results suggest that absorption of orally administered diltiazem is inhibited and delayed by cigarette smoke.

Influence of lactation on plasma phenobarbital concentrations in rats

The effect of lactation on the pharmacokinetics of phenobarbital (PB) after delivery was studied in female rats. Non-pregnant animals received PB 20 mg/kg/day twice for 6-7 days before mating, during pregnancy and after delivery. Chronic PB did not significantly influence changes in the body weight of rats after delivery. On the first post-delivery day, the plasma PB concentration in the PB-treated rats was significantly higher than that in PB-treated, non-pregnant rats (non-pregnant rats); and thereafter, it gradually decreased until ablactation on the 20th day. After ablactation, plasma PB concentrations gradually returned to the level before delivery. In PB-treated rats, pharmacokinetic parameters (Cmax, AUC0-12) of PB between 0 and 12 hr after a single oral administration were significantly decreased during lactation. These results suggest that PB administered during lactation is transferred in part to offspring through maternal milk.

Effects of nicotine and exposure to cigarette smoke on suppression of local graft-versus-host reaction induced by immobilization stress in mice

To study the effects of emotional stress on immunological activities and modification of these effects by nicotine or cigarette smoke, we evaluated the effects of immobilization stress on local graft-versus-host (GVH) reaction, a cell-mediated immune response, and the effects of nicotine and cigarette smoke on them. The effects of immobilization stress on GVH reaction and the effects of nicotine and cigarette smoke on them were evaluated in two experiments: in Experiment 1 by applying the stimulations before and immediately after spleen cell transplantation, and in Experiment 2, by applying stimulations after transplantation. Spleen cells of BALB/C mice were injected into the footpad of CBF1 mice, and GVH reaction was examined after 7 days by weighing the popliteal lymph nodes. Immobilization, nicotine administration and inhalation of cigarette smoke were performed either for 5 days before and immediately after the transplantation (Experiment 1) or for 5 days after transplantation (Experiment 2). The weight of the lymph nodes was markedly increased in the control group, indicating GVH reaction, but the reaction was suppressed by immobilization in both experiments. This suppression of GVH reaction by immobilization was antagonized by nicotine administration and exposure to cigarette smoke in Experiment 1 but not in Experiment 2. These findings suggest that nicotine and cigarette smoke induce recovery of immune response suppressed by immobilization stress, especially by increasing the competence of antigen recognition.

Pharmacokinetic evaluation of omeprazole suspension following oral administration in rats: effect of neutralization of gastric acid

In order to evaluate a clinical use of omeprazole suspension, we examined the pharmacokinetics of omeprazole after oral administration in rats. Although the administration of omeprazole suspension buffered by NaHCO3 solution did not produce a significant increase in the area under the concentration-time curve (AUC) value compared with non-buffered group, the administration of NaHCO3 buffer immediately after dosing of omeprazole suspension buffered by NaHCO3 caused a significant increase in the AUC value. These results suggest that the NaHCO3 treatment following the administration of omeprazole buffered suspension effectively decreased the degradation of the compound by gastric acid. Therefore, the successive administration of NaHCO3 solution after the omeprazole dosing seems to be a simple and useful method for the administration to patients who cannot receive tablets.

[Cephalad movement of the carina due to CD (Cotrel-Dubousset) instrumentation for idiopathic scoliosis]

Recently we experienced a case of tracheal tube obstruction due to the upward displacement of carina during CD (Cotrel-Dubousset) instrumentation for idiopathic scoliosis. Therefore, we hypothesized that CD instrumentation may affect the position of the carina as a result of correction of chest deformity, and studied the displacement of carina before and after CD instrumentation on chest X-ray in 12 patients with scoliosis. The length between the bottom of the 6th cervical vertebral body and the carina was measured by using chest X-ray before and after the correction. In all patients studied, cephalad movement of the carina was observed, and it was more than 1.00 cm in 5 patients. The maximal movement of the carina was 1.59 cm. The tracheal length after the correction was significantly shorter than before (P < 0.01). These results suggest that the carina may be displaced upwards due to the correction by the CD instrumentation, and that such induced displacement may affect the tracheal tube position and obstruct the tube during the operation.

Effect of pregnancy on plasma phenobarbital concentrations in rats

We examined the pharmacokinetics of phenobarbital before and during pregnancy in rats. Animals were divided into four groups: (a) control, (b) pregnant, (c) phenobarbital-treated, and (d) phenobarbital-treated pregnant groups. The increase in body weight of nonpregnant or pregnant rats was not influenced by long-term phenobarbital treatment. Plasma phenobarbital concentrations during the period of long-term phenobarbital treatment with a fixed dosage by body weight were not significantly affected by pregnancy. Furthermore, pregnancy did not affect pharmacokinetic parameters of phenobarbital between 0.25 and 24h after administration. These results suggest that pregnancy does not influence on the pharmacokinetics of long-term phenobarbital treatment at a fixed dosage by body weight.

Effect of cigarette smoke on lipid peroxidation and liver function tests in rats

The effect of cigarette smoke on organ weights, lipid peroxidation and plasma biochemical parameters was investigated in male Wistar rats. Daily exposure (for 20 min twice a day) to cigarette smoke for 27 days caused a significant decrease in liver weight and a significant increase in lung weight. The smoke-exposure group showed increased lipid peroxidation in the liver, but not in the lung. In the smoke-exposure group, the GOT, gamma-GTP, total bilirubin and LDH values were significantly higher than those in the control group, while the plasma glucose value was significantly lower. These results suggest that cigarette smoking might induce liver injury by enhancing lipid peroxidation.

Simple and rapid analysis of lamotrigine, a novel antiepileptic, in human serum by high-performance liquid chromatography using a solid-phase extraction technique

A simple and rapid method for the quantitation of concentrations of lamotrigine, a novel antiepileptic, in human serum was developed with high-performance liquid chromatography, using a solid-phase extraction technique. The mobile phase was composed of acetonitrile-10 mM phosphate buffer (pH 3.5) containing 5 mM sodium octanesulphonate (27:73, v/v), and components were detected at 265 nm. Retention times of acetanilide as an internal standard and lamotrigine were 3.4 and 10.3 min, respectively. The coefficients of variation were 3.1-4.5% and 4.4-9.8% for the within-day and between-day precision estimates, respectively. The extraction recovery of lamotrigine added to blank serum was 86-107%. The quantitation limit of lamotrigine was ca. 0.2 microgram/ml in 100 microliters of serum. These results suggest that the method employed in this study is useful for the routine monitoring of serum concentrations of lamotrigine in epileptic patients.

Effects of exposure to cigarette smoke on intestinal propulsion in rats

The effects of acute exposure to cigarette smoke and systemic administration of nicotine on intestinal propulsion were investigated in rats. The propulsive activity was measured as migration of charcoal powder in the intestine. This activity was suppressed by acute exposure (10 min) to cigarette smoke and by nicotine (0.5 mg/kg x 2, s.c.) administration. This intestinal suppression was more marked in the rats given nicotine than in those exposed to cigarette smoke, whereas the plasma concentrations of nicotine in both rats were similar. These results suggest that acute exposure to cigarette smoke and nicotine administration delay gastric emptying and/or suppress intestinal propulsion, and that some components other than nicotine contained in cigarette smoke may attenuate the suppression of intestinal propulsion induced by nicotine.

High susceptibility to paraquat-driven lipid peroxidation of cultured hepatocytes loaded with linolenic acid

Rat hepatocytes cultured without (normal cells) and with 1 mM alpha-linolenic acid-bovine serum albumin complex (alpha-linolenic acid [LNA]-loaded cells) for 12 hr were challenged with paraquat at concentrations ranging from 0.01 to 5 mM. The addition of paraquat to normal hepatocytes induced a relatively low level of lipid peroxidation as measured by the accumulation of malondialdehyde in the medium, even at a high paraquat concentration that caused severe cell injury. LNA-loaded hepatocytes markedly underwent lipid peroxidation on addition of paraquat, with a rise in the malondialdehyde accumulation beginning at the lowest concentration used (0.01 mM). The enhanced lipid peroxidation induced in LNA-loaded hepatocytes by the addition of paraquat was accompanied by the occurrence of cell injury at noncytotoxic paraquat concentrations for normal cells. Of further importance was that in LNA-loaded cells, lipid peroxidation promptly occurred after the addition of paraquat and was followed by the loss of cell viability. Addition of antioxidants such as N,N'-diphenyl-p-phenylenediamine and alpha-tocopherol with paraquat prevented lipid peroxidation in both normal and LNA-loaded hepatocytes but protected only the latter cells from cell injury. Neither lipid peroxidation nor cell injury in either group of hepatocytes was prevented by the presence of .OH scavengers such as mannitol and dimethyl sulfoxide. In addition, paraquat-driven lipid peroxidation in LNA-loaded hepatocytes was promoted by the addition of ascorbate but was rather suppressed by the addition of H2O2. In conclusion, it is likely that the addition of paraquat induced Fe(++)-lipid hydroperoxide-dependent lipid peroxidation that led to lethal cell injury in LNA-loaded hepatocytes.

Inhibitory effect of leupeptin on the intracellular maturation of lysosomal cathepsin L in primary cultures of rat hepatocytes

To investigate the intracellular processing event for lysosomal cathespin L, we examined the effect of leupeptin, a non-covalent cysteine proteinase inhibitor, on the intracellular processing kinetics of cathepsin L as analyzed by pulse-chase experiments in vivo with [35S]methionine in primary cultures of rat hepatocytes. This revealed that cathepsin L was initially synthesized as proenzyme of molecular weight 39 kDa and the proenzyme was subsequently processed to the mature form of the enzyme, 30 and 25 kDa. In the leupeptin-treated cells, the proteolytic conversion of cellular procathepsin L, of molecular weight 39 kDa, to the mature enzyme was significantly inhibited and considerable amounts of proenzyme were found in the cell after 8 h chase periods. Furthermore, the subcellular fractionation experiment demonstrated that the intracellular processing of procathepsin L in the high density lysosomal fraction was significantly inhibited and that considerable amounts of the procathepsin L form were still observed in the dense lysosomal fraction after a 2 h chase period. These results suggest that leupeptin treatment caused significant inhibition of the intracellular maturation of cathepsin L. These findings show that cysteine proteinase plays an important role in the intracellular proteolytic processing and activation of lysosomal cathepsin L in vivo and that this processing event occurs within the lysosomes.

Biosynthesis and processing of lysosomal cathepsin D in primary cultures of rat hepatocytes

To investigate the intracellular transport and maturation of lysosomal cathepsin D, we carried out an in vivo pulse-chase analysis with [35S]methionine in the primary cultures of rat hepatocytes. Cathepsin D was initially synthesized as a proenzyme of 45 kDa. The proenzyme was subsequently processed, becoming a mature enzyme of 43 kDa. The proenzyme and mature enzyme showed complete susceptibility to endoglycosidase H treatment, suggesting the presence of high-mannose type oligosaccharide chains. The effects of tunicamycin and chloroquine were also investigated. In the presence of tunicamycin, the 42.5-kDa unglycosylated precursor polypeptide appeared in the cell, and this protein was exclusively secreted from the cells without undergoing proteolytic processing. These results support the notion that the oligosaccharide moieties are of importance in addressing the lysosomal hydrolases to the lysosomes. However, in the presence of chloroquine, proteolytic processing of the proenzyme was prevented, and the enhanced release of proenzyme from the cells was observed. These results indicate that the processing of proenzyme to mature enzyme would take place in the lysosomes.

Influences of immobilization and footshock stress on pharmacokinetics of theophylline and caffeine in rats

The influences of immobilization and footshock stress on pharmacokinetics of theophylline (20 mg kg-1) and caffeine (30 mg kg-1) administered orally were examined in rats. The immobilization stress for 30 min or 1 h immediately after oral administration caused marked immobilization period-related decreases in plasma theophylline concentrations during the absorption phase, but did not affect plasma caffeine concentrations. The ka and Cmax values for theophylline were significantly decreased, and the tmax was significantly increased. On the other hand, when the immobilization stress was loaded for 1 or 3 h before the oral administration, the plasma theophylline or caffeine concentrations were not affected. The footshock stress for 30 min immediately after oral administration did not significantly decrease plasma theophylline concentrations during the absorption phase. These results suggest that the pharmacokinetics of theophylline are influenced by strong stress, possibly due to the inhibition of its absorption from the gastrointestinal tract, but the pharmacokinetics of caffeine are not influenced by stress, probably due to its central action.