Mammalian thioredoxin is a direct inhibitor of apoptosis signal-regulating kinase (ASK) 1

Apoptosis signal-regulating kinase (ASK) 1 was recently identified as a mitogen-activated protein (MAP) kinase kinase kinase which activates the c-Jun N-terminal kinase (JNK) and p38 MAP kinase pathways and is required for tumor necrosis factor (TNF)-alpha-induced apoptosis; however, the mechanism regulating ASK1 activity is unknown. Through genetic screening for ASK1-binding proteins, thioredoxin (Trx), a reduction/oxidation (redox)-regulatory protein thought to have anti-apoptotic effects, was identified as an interacting partner of ASK1. Trx associated with the N-terminal portion of ASK1 in vitro and in vivo. Expression of Trx inhibited ASK1 kinase activity and the subsequent ASK1-dependent apoptosis. Treatment of cells with N-acetyl-L-cysteine also inhibited serum withdrawal-, TNF-alpha- and hydrogen peroxide-induced activation of ASK1 as well as apoptosis. The interaction between Trx and ASK1 was found to be highly dependent on the redox status of Trx. Moreover, inhibition of Trx resulted in activation of endogenous ASK1 activity, suggesting that Trx is a physiological inhibitor of ASK1. The evidence that Trx is a negative regulator of ASK1 suggests possible mechanisms for redox regulation of the apoptosis signal transduction pathway as well as the effects of antioxidants against cytokine- and stress-induced apoptosis.

Three-year follow-up after implantation of metallic coronary-artery stents

BACKGROUND

Coronary-artery stents are known to reduce rates of restenosis after coronary angioplasty, but it is uncertain how long this benefit is maintained.

METHODS

We evaluated clinical and angiographic follow-up information for up to three years after the implantation of Palmaz-Schatz metallic coronary-artery stents in 143 patients with 147 lesions of native coronary arteries.

RESULTS

The rate of survival free of myocardial infarction, bypass surgery, and repeated coronary angioplasty for stented lesions was 74.6 percent at three years. After 14 months, revascularization of the stented lesion was necessary in only three patients (2.1 percent). In contrast, coronary angioplasty for a new lesion was required in 11 patients (7.7 percent). Follow-up coronary angiography of 137 lesions at six months, 114 lesions at one year, and 72 lesions at three years revealed a decrease in minimal luminal diameter from 2.54 +/- 0.44 mm immediately after stent implantation to 1.87 +/- 0.56 mm at six months, but no further decrease in diameter at one year (in patients with paired angiograms, 1.95 +/- 0.49 mm at both six months and one year). Significant late improvement in luminal diameter was observed at three years (in patients with paired angiograms, 1.94 +/- 0.48 mm at six months and 2.09 +/- 0.48 mm at three years; P < 0.001).

CONCLUSIONS

Clinical and angiographic outcomes up to three years after coronary-artery stenting were favorable, with a low rate of revascularization of the stented lesions. Late improvement in luminal diameter appears to occur between six months and three years.

Hydration and occlusion treatment for hypertrophic scars and keloids

In 31 patients with hypertrophic scars or keloids, a side by side test was carried out to check the efficacy of an occlusive dressing technique using cream which did not contain silicone oil, versus a simple application of vaseline, used as a control. In all cases, the cream treated areas of scar and keloid demonstrated a remarkable improvement over that of the vaseline treated area. These findings strongly suggest that the mechanisms of hydration and occlusion are the main basis of the therapeutic action of this method in treating hypertrophic scars and keloids.

'Albumin-mediated transport phenomenon' observed for ligands with high membrane permeability. Effect of the unstirred water layer in the Disse's space of rat liver

In this paper, we offer experimental evidence of the rate-limiting diffusion of ligands through the unstirred water layer (UWL) as an explanation for the so-called albumin-mediated transport phenomenon. The relative membrane permeability of various ligands was first evaluated using isolated rat hepatocytes. Then, the effect of albumin on the uptake of ligands of a wide range of membrane permeabilities was examined using the perfused rat liver. The results were similar to those expected from the UWL model: ligands with high membrane permeability (warfarin, diazepam and taurocholate) clearly exhibited albumin-mediated transport, those with medium membrane permeability (tolbutamide and salicylate) showed less albumin-mediated transport, and ligand with low membrane permeability (cefodizime) did not show albumin-mediated transport. These results were explained by simulation studies of two separate cases based on the UWL model; one assuming the rapid equilibrium of ligand binding with albumin, and the other considering the slow dissociation of ligands from albumin. In light of these findings, we suggest that the rate-limiting diffusion through the UWL plays an important role in the so-called albumin-mediated transport phenomenon.

Effect of bioflavonoids on vincristine transport across blood-brain barrier

Several grapefruit juice bioflavonoids, including quercetin, are reported to stimulate P-glycoprotein-mediated drug efflux from cultured tumor cells. To see whether these bioflavonoids alter the permeation of vincristine across the blood-brain barrier, we conducted experiments with cultured mouse brain capillary endothelial cells (MBEC4 cells) in vitro and ddY mice in vivo. The steady-state uptake of [3H]vincristine by MBEC4 cells was decreased by 10 microM quercetin, but increased by 50 microM quercetin. Similarly, the in vivo brain-to-plasma concentration ratio of [3H]vincristine in ddY mice was decreased by coadministration of 0.1 mg/kg quercetin, but increased by 1.0 mg/kg quercetin. Kaempferol had a similar biphasic effect on the in vitro uptake of [3H]vincristine. Other aglycones tested (chrysin, flavon, hesperetin, naringenin) increased [3H]vincristine uptake in the 10-50 microM range, and glycosides (hesperidin, naringin, rutin) were without effect. We then addressed the mechanism of the concentration-dependent biphasic action of quercetin. Verapamil, a P-glycoprotein inhibitor, inhibited the efflux of [3H]vincristine from MBEC4 cells, while 10 microM quercetin significantly stimulated it. The uptake of [3H]vincristine by MBEC4 cells was increased by inhibitors of protein kinase C, but decreased by phorbol 12-myristate-13-acetate (PMA), as well as by 10 microM quercetin. The phosphorylation level of P-glycoprotein was increased in the presence of 5 microM quercetin or 100 nM PMA, but decreased by the protein kinase C inhibitor H7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine, 30 microM). We conclude that low concentrations of quercetin indirectly activate the transport of [3H]vincristine by enhancing the phosphorylation (and hence activity) of P-glycoprotein, whereas high concentrations of quercetin inhibit P-glycoprotein. Our results indicate that patients taking drugs which are P-glycoprotein substrates may need to restrict their intake of bioflavonoid-containing foods and beverages, such as grapefruit juice.

Inhibition of vinblastine efflux mediated by P-glycoprotein by grapefruit juice components in caco-2 cells

We investigated the effect of components in grapefruit juice (GFJ) on the transport of vinblastine, a substrate of P-glycoprotein (P-gp), across Caco-2 cells. The apical to basolateral flux of [3H]vinblastine was increased in the presence of GFJ extracts. The steady-state uptake of [3H]vinblastine from the apical side was significantly increased in the presence of GFJ in a dose-dependent manner within the range of 2.5 to 50% (v/v) of GFJ. Although naringin and naringenin reduced apical efflux of [3H]vinblastine at the concentration present in GFJ and increased steady-state uptake from the apical side to 124 and 240%, respectively, the observed effect of naringin was not enough to account for the effect of GFJ and naringenin is not naturally present in GFJ. To investigate the effective components in GFJ, we examined the inhibitory effect of several organic solvent extracts of GFJ on the transport of [3H]vinblastine in Caco-2 cells. Organic solvent extracts of GFJ enhanced the apical to basolateral transcellular transport and inhibited the apical efflux. The permeability coefficient of apical to basolateral transport of [3H]vinblastine increased in the order of the ethyl acetate>diethyl ether>methylene chloride extracts of GFJ. Since the extracted amount of naringenin by ethyl acetate was less than that with the other organic solvents, the primary inhibitor in GFJ is suggested to be different from this flavonoid. The present study demonstrated the existence of inhibitory components in GFJ for the P-gp function in Caco-2 cells, which are distinct from known components such as naringin or naringenin.

Blood pressure publication guidelines. Society for Psychophysical Research

Blood pressure is one of the most commonly recorded functions in physiology and medicine, and it has become a major variable in recent psychophysiological and behavioral medicine research. Many methods have been developed for the measurement of blood pressure in clinical, laboratory, and natural settings. The broad objectives of this report are to summarize the most critical methodological issues in the measurement of blood pressure and to present principles and recommendations for the evaluation of blood pressure methods and findings in published studies.

Human placental transport of vinblastine, vincristine, digoxin and progesterone: contribution of P-glycoprotein

To elucidate the role of P-glycoprotein in human placenta, we examined its expression in placenta, and the transcellular transport and uptake of P-glycoprotein substrates in cultured human placental choriocarcinoma epithelial cells (BeWo cells). The uptake of [(3)H]vinblastine and [(3)H]vincristine into BeWo cells was increased in the presence of a metabolic inhibitor, sodium azide. The basolateral-to-apical transcellular transport of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin was greater than the apical-to-basolateral transcellular transport. In the presence of cyclosporin A, the basolateral-to-apical transcellular transport of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin was significantly increased, and the apical-to-basolateral transcellular transport was decreased. The uptake of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin into BeWo cells was significantly enhanced in the presence of several inhibitors, such as verapamil or mouse monoclonal antibody anti-P-glycoprotein MX-MDR (MRK16) as well as cyclosporin A. Although progesterone significantly enhanced the uptake of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin into BeWo cells, the uptake of [(3)H]progesterone was not affected by these inhibitors. Immunoblot analysis revealed that P-glycoprotein with a molecular weight of 172 kDa was expressed in BeWo cells and isolated trophoblast cells. Furthermore, P-glycoprotein was detected in human placental brush-border membrane vesicles, but not in human placental basolateral membrane vesicles. In conclusion, these data suggest that P-glycoprotein is expressed on the brush-border membrane (maternal side) of human placental trophoblast cells. P-Glycoprotein is considered to regulate the transfer of several substances including vinblastine, vincristine and digoxin from mother to fetus, and to protect the fetus from toxic substances.

Structure and gene organization in the transformed Hind III-G fragment of Ad12

The nucleotide sequence of the transforming Hind III-G fragment of Ad12 DNA which encompasses the left 6.8% of the genome has been determined. The fragment was 2320 nucleotides long, and contained a GC cluster at positions 126-155 and a region extremely rich in AT at positions 1098-1142 (number from the leftmost end). Possible coding regions for the two transforming gene products were assigned. The predicted coding region for T antigen g is positions 502-1069 and positions 1144-1373, which are joined by splicing (266 amino acid residues, 30 kd), and that for T antigen f is positions 1845-2126 (94 amino acid residues, 10 kd). The sequence of the Hind III-G fragment was compared with that of the transforming DNA fragment of Ad5 which encompasses the left 8.0% of the genome (2809 nucleotides). There are several discrete regions with significant sequence homology. The comparison suggests that the regions in the left two thirds of the Ad5 and Ad12 transforming DNA fragments (map units 0-4.7% in Ad5 and 0-4.4% in Ad12) bear some resemblance in their gene organizations, and code for proteins containing structurally homologous regions.

Apoptosis signal-regulating kinase 1 (ASK1) is an intracellular inducer of keratinocyte differentiation

Cells differentiate in response to various extracellular stimuli. This cellular response requires intracellular signaling pathways. The mitogen-activated protein (MAP) kinase cascade is a core signal transduction pathway that determines the fate of many kinds of cell. MAP kinase kinase kinase activates MAP kinase kinase, which in turn activates MAP kinase. Apoptosis signal-regulating kinase (ASK1) was identified as a MAP kinase kinase kinase involved in the stress-induced apoptosis-signaling cascade that activates the SEK1-JNK and MKK3/MKK6-p38 MAP kinase cascades. Expression of the constitutively active form of ASK1 (ASK1-DeltaN) in keratinocytes induced significant morphological changes and differentiation markers, transglutaminase-1, loricrin, and involucrin. A transient increase in p21(Cip1/WAF1) reduced DNA synthesis, and cell cycle analysis verified the differentiation. p38 MAP kinase inhibitors, SB202190 and SB203580, abolished the induction of differentiation markers, transglutaminase-1, loricrin, and involucrin. In turn, the induction of differentiation with ceramide in keratinocytes caused an increase in ASK1 expression and activity. Furthermore, normal human skin expresses ASK1 protein in the upper epidermis, implicating ASK1 in in vivo keratinocyte differentiation. We propose that the ASK1-p38 MAP kinase cascade is a new intracellular regulator of keratinocyte differentiation.

Assessment of baroreceptor reflex function during mental stress and relaxation

This paper describes a method of measuring baroreceptor cardiac reflex sensitivity noninvasively from spontaneous patterns of blood pressure and interbeat interval, and the application of this technique in psychophysiology. Baroreflex function was assessed in 24 female volunteers during relaxation and performance of the cold pressor test and a non-verbal mental arithmetic task. Blood pressure and interbeat interval were monitored continuously from the finger using the vascular unloading technique. Sequences of three or more cardiac cycles were identified over which systolic blood pressure increased progressively in conjunction with lengthening interbeat interval, or systolic blood pressure decreased as interbeat interval was reduced. The regression between systolic blood pressure and interbeat interval was computed as an index of baroreflex sensitivity. Relaxation was associated with a small prolongation of interbeat interval, whereas baroreflex sensitivity increased from 17.1 to 19.8 ms/mmHg. Baroreflex sensitivity was reduced significantly during mental arithmetic (mean 14.2 ms/mmHg) but not during the cold pressor test (mean 17.4 ms/mmHg). The difference between mental arithmetic and the cold pressor test may be related to the relative intensity of cardiac and vascular responses in the two situations. The implications of these results for the understanding of behavioural influences on haemodynamic function are discussed and the advantages of noninvasive methods are considered.

Prediction of the disposition of beta-lactam antibiotics in humans from pharmacokinetic parameters in animals

Various pharmacokinetic parameters (disposition half-life, total body clearance, renal clearance, hepatic clearance, volume of distribution, intrinsic clearance and volume of distribution of unbound drug) of six beta-lactam antibiotics were compared in mouse, rat, rabbit, dog, monkey, and human. Two methods for prediction of the disposition of the beta-lactam antibiotics in humans by extrapolation of the animal data were evaluated. One was the Adolph-Dedrick approach, which can be used to predict clearances in humans from the relationship between intrinsic clearances and body weight in the other five species. The volume of distribution in humans was predicted from the relationship between the volume of distribution and serum unbound fraction in the five species. The other was the Boxenbaum approach, which can be used to predict the pharmacokinetic parameters of the six beta-lactam antibiotics in humans by using the regression lines of log-log plots of intrinsic clearance and volume of distribution of unbound drug in a single species, in this case the monkey. The half-life calculated according to the latter method had a smaller absolute error than that calculated according to the former method, but the better method for extrapolation of animal data to humans seems to be the former method, which does not require a priori information regarding structure-pharmacokinetic relationships among the antibiotics.

The identification of an orally active, nonpeptide bradykinin B2 receptor antagonist, FR173657

1. An orally active, nonpeptide bradykinin (BK) B2 receptor antagonist, FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[N-[2-4-dichloro-3-[(2-methyl-8-quinolin yl) oxymethyl]phenyl]-N-methylaminocarbonyl-methyl] acrylamide) has been identified. 2. This compound displaced [3H]-BK binding to B2 receptors present in guinea-pig ileum membranes with an IC50 of 5.6 x 10(-10) M and in rat uterus with an IC50 of 1.5 x 10(-9) M. It did not inhibit different specific radio-ligand binding to other receptor sites. 3. In human lung fibroblast IMR-90 cells, FR173657 displaced [3H]-BK binding to B2 receptors with an IC50 of 2.9 x 10(-9) M and a Ki of 3.6 x 10(-10) M, but did not reduce [3H]-des]Arg10-kallidin binding to B1 receptors. 4. In guinea-pig isolated preparations, FR173657 antagonized BK-induced contractions with an IC50 of 7.9 x 10(-9) M, but did not antagonize acetylcholine or histamine-induced contractions even at a concentration of 10(-6) M. FR173657 caused parallel rightward shifts of the concentration-response curves to BK at concentrations of 10(-9) M and 3.2 x 10(-9) M, and a little depression of the maximal response in addition to the parallel rightward shift of the concentration-response curve at a concentration of 10(-8) M. Analysis of the data yield a pA2 of 9.2 +/- 0.2 (n = 5) and a slope of 1.5 +/- 0.2 (n = 5). 5. In vivo, the oral administration of FR173657 inhibited BK-induced bronchoconstriction dose-dependently in guinea-pigs with an ED50 of 0.075 mg kg-1, but did not inhibit histamine-induced bronchoconstriction even at 1 mg kg-1. FR173657 also inhibited carrageenin-induced paw oedema with an ED50 of 6.8 mg kg-1 2 h after the carrageenin injection in rats. 6. These results show that FR173657 is a potent, selective, and orally active bradykinin B2 receptor antagonist.

Diffusion and deformations of single hydra cells in cellular aggregates

Cell motion within cellular aggregates consists of both random and coherent components. We used confocal microscopy to study the center of mass displacements and deformations of single endodermal Hydra cells in two kinds of cellular aggregates, ectodermal and endodermal. We first carefully characterize the center of mass displacements using standard statistical analysis. In both aggregates, cells perform a persistent random walk, with the diffusion constant smaller in the more cohesive endodermal aggregate. We show that a simple parametric method is able to describe cell deformations and relate them to displacements. These deformations are random, with their amplitude and direction uncorrelated with the center of mass motion. Unlike for an isolated cell on a substrate, the random forces exerted by the surrounding cells predominate over the deformation of the cell itself, causing the displacements of a cell within an aggregate.

Stretch-induced hypertrophic growth of cardiocytes and processing of brain-type natriuretic peptide are controlled by proprotein-processing endoprotease furin

When hypertrophic growth is induced in neonatal rat cardiocytes by stretching, the cardiocytes express high levels of brain-type natriuretic peptide (BNP) and the proprotein-processing enzyme furin. A BNP precursor, gammaBNP, possesses a furin-cleavable Arg-X-X-Arg motif, which is cleaved when gammaBNP is processed to form BNP-45. The Arg-X-X-Arg motif is found in many precursors of growth factors and growth-related proteins. To determine if furin converts gammaBNP to BNP-45 as well as other unidentified growth-promoting protein precursors to their active form that may induce hypertrophic growth in cardiocytes, we used two protease inhibitor systems, synthetic peptidyl chloromethyl ketones (CMK) (dec-Arg-Val-Lys-Arg-CMK and dec-Phe-Ala-Lys-Arg-CMK; where dec is decanoyl) and vaccinia vector-integrated native and variant alpha1-antitrypsins. The furin-specific inhibitors, dec-Arg-Val-Lys-Arg-CMK and variant alpha1-antitrypsin with the inhibitory determinant Arg-X-X-Arg, suppressed the stretch-induced hypertrophic growth of cardiocytes as well as the processing of gammaBNP to BNP-45. The other serine protease inhibitors and variant alpha1-antitrypsin against elastase, or thrombin, however, neither suppressed the hypertrophic growth nor prevented the processing of gammaBNP to BNP-45. Thus, we suggest that furin catalyzes the conversion of gammaBNP to BNP-45 as well as growth-promoting proproteins to their active form, which might induce hypertrophic growth in cardiocytes.

Relation between redox potentials and rate constants in reactions coupled with the system oxygen-superoxide

Univalent oxidation-reduction reactions coupled with the oxygen-superoxide system were investigated in the reactions shown in eq 3 and 8, where Q and Q.- stand for p-benzoquinone and p-benzosemiquinone, respectively. From kinetic experiments the following rate constants were obtained at pH 7.0:k3 = 4.5 x 10(4) M-1 sec-1 and k8 = 3 x 10(-2) M-1 sec-1. With known values of k-3 and k-8, and of E0' for the systems Q-Q.- (0.10 V) and Cyt c3+ - Cyt c2+ (0.255 V), the calculated values of E0(O2-O2.-) were found to lie in the range between -0.27 and -0.33 V.

New technique for time series analysis combining the maximum entropy method and non-linear least squares method: its value in heart rate variability analysis

A new technique for time series analysis, which is a combination of the maximum entropy method (MEM) for spectral analysis and the non-linear least squares method (LSM) for fitting analysis, is described. In this technique, the MEM power spectral density (MEMPSD) is calculated using a very large lag that could diminish the lag dependence of dominant periods estimated by the MEM analysis. The validity of this large lag is confirmed by the LSM, given that the ten dominant MEM periods are known quantities. To validate the MEM plus LSM technique, it is compared with autoregressive (AR) modelling, by analysing heart rate variability under pharmacological interventions (phenylephrine and trinitroglycerine), using 16 young males. The results indicate that the MEMPSD, when compared with the ARPSD, has numerous periods that could reproduce the original time series much more accurately, as revealed by the LSM analysis. However, both the low- and high-frequency powers with MEMPSD and ARPSDs shift in the expected directions in accordance with the pharmacological effects on the cardiovascular system. The implications of these results are discussed from the theoretical and practical standpoints of the MEM plus LSM technique, compared with AR modelling.

Relationship between time after intake of grapefruit juice and the effect on pharmacokinetics and pharmacodynamics of nisoldipine in healthy subjects

A clinical study was performed in eight healthy volunteers to investigate the effect of various timing of grapefruit juice intake on nisoldipine pharmacokinetics and pharmacodynamics, and to validate our pharmacokinetic model. The subjects were given 10 mg oral nisoldipine with water (control), or 5 mg oral nisoldipine with 200 mL grapefruit juice (G0) or with water at 14 (G14), 38 (G38), 72 (G72) or 96 hours (G96) after a 7-day period of thrice-daily intake of grapefruit juice. Grapefruit juice ingestion did not affect heart rate or the effect area during the first 8 hours of heart rate after nisoldipine administration, although significant decreases of systolic and diastolic blood pressure were caused in G0 by coadministration of grapefruit juice with nisoldipine. Headaches were reported by 3, 2, and 1 persons in G0, G14, and G38, respectively, but no subjects in G72 and G96 reported headaches. Compared with the control group, the maximum plasma concentration of nisoldipine was significantly increased after grapefruit juice intake in G0 and G14, and the plasma concentration was significantly increased at each time in G0 to G72. Therefore the effect of grapefruit juice decreased time dependently and lasted for at least 3 days after intake. Furthermore, our model gave predicted values in good agreement with the observed values. It is therefore necessary to withhold grapefruit juice for at least 3 days before administration of the drug to prevent grapefruit juice-nisoldipine interaction.

Treatment of scars and keloids with a cream containing silicone oil

The clinical effect of silicone cream containing 20% of silicone oil was tested on 47 patients with hypertrophic scars and keloids. A silicone cream/occlusive dressing technique, quite similar in manner to silicone gel treatment, resulted in a remarkable improvement of scars and keloids in 9 of 11 cases (82%) whereas the simple application of the cream onto the scars and keloids of 36 cases resulted in only mild improvement in 8 (22%). Using the chi-square test, a statistically significant difference was seen between these two treatments (p less than 0.01). From these findings, we suggest that occlusion and hydration are the principal modes of action of the silicone gel sheet method and our silicone cream/occlusive dressing technique.

Increased ghrelin signaling prolongs survival in mouse models of human aging through activation of sirtuin1

Caloric restriction (CR) is known to retard aging and delay functional decline as well as the onset of diseases in most organisms. Ghrelin is secreted from the stomach in response to CR and regulates energy metabolism. We hypothesized that in CR ghrelin has a role in protecting aging-related diseases. We examined the physiological mechanisms underlying the ghrelin system during the aging process in three mouse strains with different genetic and biochemical backgrounds as animal models of accelerated or normal human aging. The elevated plasma ghrelin concentration was observed in both klotho-deficient and senescence-accelerated mouse prone/8 (SAMP8) mice. Ghrelin treatment failed to stimulate appetite and prolong survival in klotho-deficient mice, suggesting the existence of ghrelin resistance in the process of aging. However, ghrelin antagonist hastened death and ghrelin signaling potentiators rikkunshito and atractylodin ameliorated several age-related diseases with decreased microglial activation in the brain and prolonged survival in klotho-deficient, SAMP8 and aged ICR mice. In vitro experiments, the elevated sirtuin1 (SIRT1) activity and protein expression through the cAMP-CREB pathway was observed after ghrelin and ghrelin potentiator treatment in ghrelin receptor 1a-expressing cells and human umbilical vein endothelial cells. Furthermore, rikkunshito increased hypothalamic SIRT1 activity and SIRT1 protein expression of the heart in the all three mouse models of aging. Pericarditis, myocardial calcification and atrophy of myocardial and muscle fiber were improved by treatment with rikkunshito. Ghrelin signaling may represent one of the mechanisms activated by CR, and potentiating ghrelin signaling may be useful to extend health and lifespan.

P-glycoprotein-mediated transport of itraconazole across the blood-brain barrier

The mechanism for the accumulation of itraconazole (ITZ) in its elimination from the brain was studied in rats and mice. The concentration of ITZ in liver tissue declined in parallel with the plasma ITZ concentration until 24 h after intravenous injection of the drug (half-life, 5 h); however, the ITZ in brain tissue rapidly disappeared (half-life, 0.4 h). The time profiles of the brain/plasma ITZ concentration ratio (Kp value) showed a marked overshooting, and the Kp value increased with increasing dose; these phenomena were not observed in the liver tissue. This finding indicates the occurrence of a nonlinear efflux of ITZ from the brain to the blood. Moreover, based on a pharmacokinetic model which hypothesized processes for both nonlinear and linear effluxes of ITZ from the brain to the blood, we found that the efflux rate constant in the saturable process was approximately sevenfold larger than that in the nonsaturable process. The Kp value for the brain tissue was significantly increased in the presence of ketoconazole or verapamil. The brain Kp value for mdr1a knockout mice was also significantly increased compared with that of control mice. Moreover, the uptake of vincristine or vinblastine, both of which are substrates of the P glycoprotein (P-gp), into mouse brain capillary endothelial cells was also significantly increased by ITZ or verapamil. In conclusion, P-gp in the brain capillary endothelial cells participates in a process of active efflux of ITZ from the brain to the blood at the blood-brain barrier, and ITZ can be an inhibitor of various substrates of P-gp.