Effects of telmisartan and olmesartan on insulin sensitivity and renal function in spontaneously hypertensive rats fed a high fat diet

Although telmisartan, an angiotensin II receptor blocker (ARB), has an agonistic action for proliferator-activated receptor (PPAR)-γ in vitro, it remains to be determined whether telmisartan exerts such an action in vivo using a non-toxic dose (<5 mg/kg in rats). To address the issue, telmisartan (2 mg/kg) and olmesartan (2 mg/kg), another ARB without PPAR-γ agonistic action, were given to spontaneously hypertensive rats (SHR) fed a high fat diet (HFD). HFD decreased plasma adiponectin, and caused insulin resistance, hypertriglyceridemia and renal damage, which were improved by ARBs. Protective effects of telmisartan and olmesartan did not significantly differ. In addition, in vitro study showed that 1 μM of telmisartan did not elevate the mRNA expression of adipose protein 2, which is a PPAR-γ-stimulated adipogenic marker gene, in preadipocytes with 3% albumin. To obtain 1 μM of plasma concentration, oral dose of telmisartan was calculated to be 6 mg/kg, which indicates that PPAR-γ agonistic action is negligible with a non-toxic dose of telmisartan (<5 mg/kg) in rats. This study showed that 2 mg/kg of telmisartan and olmesartan ameliorated insulin resistance, hypertriglyceridemia and renal damage in SHR fed a HFD. As beneficial effects of telmisartan and olmesartan did not significantly differ, these were mediated through the PPAR-γ-independent actions.

Analysis of individual differences in radiosensitivity using genome editing

Current standards for radiological protection of the public have been uniformly established. However, individual differences in radiosensitivity are suggested to exist in human populations, which could be caused by nucleotide variants of DNA repair genes. In order to verify if such genetic variants are responsible for individual differences in radiosensitivity, they could be introduced into cultured human cells for evaluation. This strategy would make it possible to analyse the effect of candidate nucleotide variants on individual radiosensitivity, independent of the diverse genetic background. However, efficient gene targeting in cultured human cells is difficult due to the low frequency of homologous recombination (HR) repair. The development of artificial nucleases has enabled efficient HR-mediated genome editing to be performed in cultured human cells. A novel genome editing strategy, 'transcription activator-like effector nuclease (TALEN)-mediated two-step single base pair editing', has been developed, and this was used to introduce a nucleotide variant associated with a chromosomal instability syndrome bi-allelically into cultured human cells to demonstrate that it is the causative mutation. It is proposed that this editing technique will be useful to investigate individual radiosensitivity.

Membrane depolarization-induced RhoA/Rho-associated kinase activation and sustained contraction of rat caudal arterial smooth muscle involves genistein-sensitive tyrosine phosphorylation

Rho-associated kinase (ROK) activation plays an important role in K⁺-induced contraction of rat caudal arterial smooth muscle (Mita et al., Biochem J. 2002; 364: 431–40). The present study investigated a potential role for tyrosine kinase activity in K⁺-induced RhoA activation and contraction. The non-selective tyrosine kinase inhibitor genistein, but not the src family tyrosine kinase inhibitor PP2, inhibited K⁺-induced sustained contraction (IC₅₀ = 11.3 ± 2.4 µM). Genistein (10 µM) inhibited the K⁺-induced increase in myosin light chain (LC₂₀) phosphorylation without affecting the Ca²⁺ transient. The tyrosine phosphatase inhibitor vanadate induced contraction that was reversed by genistein (IC₅₀ = 6.5 ± 2.3 µM) and the ROK inhibitor Y-27632 (IC₅₀ = 0.27 ± 0.04 µM). Vanadate also increased LC₂₀ phosphorylation in a genistein- and Y-27632-dependent manner. K⁺ stimulation induced translocation of RhoA to the membrane, which was inhibited by genistein. Phosphorylation of MYPT1 (myosin-targeting subunit of myosin light chain phosphatase) was significantly increased at Thr855 and Thr697 by K⁺ stimulation in a genistein- and Y-27632-sensitive manner. Finally, K⁺ stimulation induced genistein-sensitive tyrosine phosphorylation of proteins of ∼55, 70 and 113 kDa. We conclude that a genistein-sensitive tyrosine kinase, activated by the membrane depolarization-induced increase in [Ca²⁺]_i, is involved in the RhoA/ROK activation and sustained contraction induced by K⁺. Ca²⁺ sensitization, myosin light chain phosphatase, RhoA, Rho-associated kinase, tyrosine kinase

Inhibition of CYP3A4 by 6',7'-dihydroxybergamottin in human CYP3A4 over-expressed hepG2 cells

OBJECTIVES

We previously established HepG2-GS-3A4, a cell line from hepatoblastoma with overexpression of human CYP3A4 and glutamine synthetase (GS). We further reported that these cells can be applied for screening inhibitors of CYP3A4 in vitro. The purpose of this study was to determine whether our CYP3A4-overexpresed cell could be applied to evaluate mechanisms of CYP3A4 inhibition by 6',7'-dihydroxybergamottin (DHB), which is one of the major furanocoumarins in grapefruit juice, by using these cells.

METHODS

Nifedipine oxidation, activity and protein expression of NADPH-cytochrome reductase (POR) of HepG2-GS-3A4 cell were measured. CO-binding spectrumassay in microsomal fraction of the cells was also evaluated.

KEY FINDINGS

DHB and ketoconazole, a well-known inhibitor of CYP3A4, inhibited nifedipine oxidation in a concentration-dependent manner. DHB at a concentration of 3.0 µm, sufficient to inhibit the nifedipine oxidation, decreased POR activity; however, ketoconazole at a concentration of 0.9 µm, sufficient to inhibit the oxidation, did not affect the activity. The expression of POR protein in HepG2-GS-3A4 cells was not changed by either DHB or ketoconazole. The expression of CYP3A4 mRNA and protein was not changed by the addition of DHB or ketoconazole. DHB also reduced the absorption rate at 450 nm in a CO-binding spectrum assay without alteration of the wavelength of maximum absorption. The mean absorption value at 450 nm slightly decreased with ketoconazole; however, the difference was not significant.

CONCLUSIONS

We concluded that inhibition of CYP3A4 activity by DHB includes the inhibition of POR activity. HepG2-GS-3A4 might be a good tool to evaluate the mechanisms.

Effects of atorvastatin and pravastatin on glucose tolerance, adipokine levels and inflammatory markers in hypercholesterolaemic patients

Several randomized clinical trials have suggested that atorvastatin and pravastatin may differ in terms of their pleiotropic effects. To verify this, we compared the effects of both statins on glucose tolerance, adipokine concentrations and inflammatory markers. A total of 36 hypercholesterolaemic patients without known coronary heart disease (CHD) were enrolled in an open-label, randomized, crossover study. The patients received pravastatin or atorvastatin (10 mg/day) for 4 months and then switched to the other statin for an additional 4 months. At the end of both treatment periods, atorvastatin significantly reduced the concentration of serum lipids (total and low-density lipoprotein-cholesterol and triglycerides) and inflammatory markers (high-sensitivity C-reactive protein and tumour necrosis factor-a) and increased serum adiponectin levels compared with pravastatin treatment. Although these effects would be expected to improve insulin sensitivity, atorvastatin did not affect glucose tolerance, which was assessed by fasting glucose and insulin concentrations, the homeostasis model assessment index and glycosylated haemoglobin (HbA(1c)) levels. Only obese patients showed increased HbA(1c) levels after atorvastatin treatment. Our results suggest that atorvastatin has both advantages and disadvantages compared with pravastatin treatment. Further studies are required to compare the relative clinical value of atorvastatin and pravastatin, especially in obese patients without CHD.

The role of topological spin defects in magnetotransport of CrO(2)

We investigated the temperature dependence of the resistivity for a wide temperature range for CrO(2)(100) epitaxial films. The temperature derivative dρ/dT definitely shows the same character as the magnetic heat capacity anomaly in the critical regime even in a finite magnetic field and the critical exponents (α) deduced are consistent with those of 3D Heisenberg ferromagnets. In addition, we found that the spin dependent resistivity over a wide temperature range can be simply proportional to the density of diluted topological spin defects (Skyrmion strings) suggesting that those nontrivial topological defects scatter conduction electrons just like impurities. The excitation energy of such topological defects is quite comparable to that obtained by anomalous Hall effect analysis of the Ye et al model based on the Berry phase. The overall results give a simple picture wherein the density of the topological defects can be a dominant mechanism of resistivity, like the anomalous Hall effect. The results concerning the critical exponent analysis and intuition concerning scattering centres of magnetic disorder suggest a specific picture of the Fisher-Langer model.

High-fat feeding exerts minimal effects on rhythmic mRNA expression of clock genes in mouse peripheral tissues

Recent studies have suggested that the impairment of the circadian molecular clock in peripheral tissues, including adipose tissue, is involved in the development of metabolic syndrome. Although the disorder is often caused by dietary obesity, it remains to be elucidated whether dietary obesity or high-caloric intake per se affects the molecular clock system. To address this issue, this study investigated the effect of high-fat feeding on the rhythmic mRNA expression of clock genes (Clock, Bmal1, Per1, Per2, Cry1, Cry2, and Dbp) in mouse visceral adipose tissue and liver. Mice fed a high-fat diet for 8 wks developed a mild but overt metabolic syndrome of obesity, hyperlipidemia, and hyperglycemia. However, the high-fat feeding had only minimal effects on the rhythmic expression of the clock genes examined in both tissues. On the other hand, daily rhythmicity in the transcript level of cholesterol 7alpha-hydroxylase, a hepatic enzyme controlling circadian cholesterol homeostasis, disappeared in the mice on high-fat chow. These results suggest that high-fat feeding and mild metabolic syndrome scarcely alter the molecular clock system in mouse peripheral tissues, and that physiological circadian rhythms could be affected without altering the system. Further studies are needed to better understand the role of the circadian molecular clock in the development of metabolic syndrome. The first two authors contributed equally to this study.

Dynamics of water droplets detached from porous surfaces of relevance to PEM fuel cells

The detachment of liquid droplets from porous material surfaces used with proton exchange membrane (PEM) fuel cells under the influence of a cross-flowing air is investigated computationally and experimentally. CCD images taken on a purpose-built transparent fuel cell have revealed that the water produced within the PEM is forming droplets on the surface of the gas-diffusion layer. These droplets are swept away if the velocity of the flowing air is above a critical value for a given droplet size. Static and dynamic contact angle measurements for three different carbon gas-diffusion layer materials obtained inside a transparent air-channel test model have been used as input to the numerical model; the latter is based on a Navier-Stokes equations flow solver incorporating the volume of fluid (VOF) two-phase flow methodology. Variable contact angle values around the gas-liquid-solid contact-line as well as their dynamic change during the droplet shape deformation process, have allowed estimation of the adhesion force between the liquid droplet and the solid surface and successful prediction of the separation line at which droplets loose their contact from the solid surface under the influence of the air stream flowing around them. Parametric studies highlight the relevant importance of various factors affecting the detachment of the liquid droplets from the solid surface.

Profile of rhythmic gene expression in the livers of obese diabetic KK-Ay mice

Although a number of genes expressed in most tissues, including the liver, exhibit circadian regulation, gene expression profiles are usually examined only at one scheduled time each day. In this study, we investigated the effects of obese diabetes on the hepatic mRNA levels of various genes at 6-h intervals over a single 24-h period. Microarray analysis revealed that many genes are expressed rhythmically, not only in control KK mice but also in obese diabetic KK-A(y) mice. Real-time quantitative PCR verified that 19 of 23 putative circadianly expressed genes showed significant 24-h rhythmicity in both strains. However, obese diabetes attenuated these expression rhythms in 10 of 19 genes. More importantly, the effects of obese diabetes were observed throughout the day in only two genes. These results suggest that observation time influences the results of gene expression analyses of genes expressed circadianly.

Effects of grapefruit juice on the pharmacokinetics of pitavastatin and atorvastatin

AIMS

To compare the effects of grapefruit juice (GFJ) on the pharmacokinetics of pitavastatin and atorvastatin.

METHODS

In a randomized, four-phase crossover study, eight healthy subjects consumed either GFJ or water t.i.d. for 4 days in each trial. On each final day, a single dose of 4 mg pitavastatin or 20 mg atorvastatin was administered.

RESULTS

GFJ increased the mean AUC(0-24) of atorvastatin acid by 83% (95% CI 23-144%) and that of pitavastatin acid by 13% (-3 to 29%).

CONCLUSIONS

Pitavastatin, unlike atorvastatin, appears to be scarcely affected by the CYP3A4-mediated metabolism.

Rhythmic messenger ribonucleic acid expression of clock genes and adipocytokines in mouse visceral adipose tissue

Various peripheral tissues show circadian rhythmicity, which is generated at the cellular level by their own core oscillators that are composed of transcriptional/translational feedback loops involving a set of clock genes. Although the circulating levels of some adipocytokines, i.e. bioactive substances secreted by adipocytes, are on a 24-h rhythmic cycle, it remains to be elucidated whether the clock gene system works in adipose tissue. To address this issue, we investigated the daily mRNA expression profiles of the clock genes and adipocytokines in mouse perigonadal adipose tissues. In C57BL/6J mice, all transcript levels of the clock genes (Bmal1, Per1, Per2, Cry1, Cry2, and Dbp) and adipocytokines (adiponectin, resistin, and visfatin) clearly showed 24-h rhythms. On the other hand, the rhythmic expression of these genes was mildly attenuated in obese KK mice and greatly attenuated in more obese, diabetic KK-A(y) mice. Obese diabetes also diminished the rhythmic expression of the clock genes in the liver. Interestingly, a 2-wk treatment of KK and KK-A(y) mice with pioglitazone impaired the 24-h rhythmicity of the mRNA expression of the clock genes and adipocytokines despite the antidiabetic effect of the drug. In contrast, pioglitazone improved the attenuated rhythmicity in the liver. These findings suggest that the intracellular clock gene system acts in visceral adipose tissues as well as liver and is influenced by the conditions of obesity/type 2 diabetes and pioglitazone treatment.

Daily rhythms of P-glycoprotein expression in mice

Recent studies have shown the gene expression of several transporters to be circadian rhythmic. However, it remains to be elucidated whether the expression of P-glycoprotein, which is involved in the transport of many medications, undergoes 24 h rhythmicity. To address this issue, we investigated daily profiles of P-glycoprotein mRNA and protein levels in peripheral mouse tissues. In the liver and intestine, but not in the kidney, Abcb1a mRNA expression showed clear 24 h rhythmicity. On the other hand, Abcb1b and Abcb4, the other P-glycoprotein genes, did not exhibit significant rhythmic expression in the studied tissues. In the intestine, levels of whole P-glycoprotein also exhibited a daily rhythm, with a peak occurring in the latter half of the light phase and a trough at the onset of the light phase. Consistent with the day-night change of P-glycoprotein level, the ex vivo accumulation of digoxin, an Abcb1a P-glycoprotein substrate, into the intestinal segments at the onset of dark phase was significantly lower than it was at the onset of the light phase. Thus, Abcb1a P-glycoprotein expression, and apparently its function, are 24 h rhythmic at least in mouse intestine tissue. This circadian variation might be involved in various chronopharmacological phenomena.

In vivo assessment of the cutaneous bioavailability of topically applied maxacalcitol

Maxacalcitol (22-oxacalcitriol), a vitamin D3 analogue, is widely used for the treatment of psoriasis. The effects of topical dermatologic drugs have been assessed by their pharmacodynamic activities, and concentrations in the skin correlate with these activities. In this study, we assessed the cutaneous bioavailability of topically applied maxacalcitol ointment in vivo by tape stripping. Six drug application sites were randomly assigned on the left volar forearm of six healthy men. Fifty milligrams of maxacalcitol ointment (25 microg/g) was applied to each site. After 0 (15 s), 0.5, 1, 2, 4, or 6 h, the ointment was gently removed, and tape stripping was performed. Maxacalcitol was extracted from the tape strips and quantified by liquid chromatographic tandem mass spectrometry. Average concentrations of maxacalcitol in the stratum corneum (SC) were 2.61, 4.37, 6.23, 9.37, and 9.46 microg/g at 0.5, 1, 2, 4, and 6 h, respectively, after drug application. The steady state was attained approx. 4 h after drug application. The cutaneous bioavailability of topical maxacalcitol ointment can be assessed by the tape-stripping method. This approach will probably be useful in the assessment of the bioequivalence of topical dermatologic products and as a parameter for pharmacokinetic/pharmacodynamic studies.

Skyrmion strings and the anomalous Hall effect in CrO2

Topological (or singularity point) defects are thought to play a crucial role in the phase transitions of 3D spin systems, as they do in such 2D systems as the XY model. In double-exchange ferromagnets the conduction electrons are strongly coupled with core spins through Hund's rule, and, in the presence of a nontrivial spin texture, acquire a Berry phase contribution to the anomalous Hall effect. We combine Hall effect and magnetization data on CrO2 with a thermodynamical scaling hypothesis to confirm that the critical behavior of the topological-spin-defect density is consistent with that of the heat capacity. This analysis is the first experimental confirmation of the topological character of critical fluctuations.

Membrane depolarization-induced contraction of rat caudal arterial smooth muscle involves Rho-associated kinase

Depolarization of the sarcolemma of smooth muscle cells activates voltage-gated Ca2+ channels, influx of Ca2+ and activation of cross-bridge cycling by phosphorylation of myosin catalysed by Ca2+/calmodulin-dependent myosin light-chain kinase (MLCK). Agonist stimulation of smooth muscle contraction often involves other kinases in addition to MLCK. In the present study, we address the hypothesis that membrane depolarization-induced contraction of rat caudal arterial smooth muscle may involve activation of Rho-associated kinase (ROK). Addition of 60 mM K+ to de-endothelialized muscle strips in the presence of prazosin and propranolol induced a contraction that peaked rapidly and then declined to a steady level of force corresponding to approx. 30% of the peak contraction. This contractile response was abolished by the Ca2+-channel blocker nicardipine or the removal of extracellular Ca2+. An MLCK inhibitor (ML-9) inhibited both the phasic and tonic components of K+-induced contraction. On the other hand, the ROK inhibitors Y-27632 and HA-1077 abolished the tonic component of K+-induced contraction, and slightly reduced the phasic component. Phosphorylation levels of the 20-kDa light chain of myosin increased rapidly in response to 60 mM K+ and subsequently declined to a steady-state level significantly greater than the resting level. Y-27632 abolished the sustained and reduced the phasic elevation of the phosphorylation of the 20-kDa light chain of myosin, without affecting the K+-induced elevation of cytosolic free Ca2+ concentration. These results indicate that ROK activation plays an important role in the sustained phase of K+-induced contraction of rat caudal arterial smooth muscle, but has little involvement in the phasic component of K+-induced contraction. Furthermore, these results are consistent with inhibition of myosin light-chain phosphatase by ROK, which would account for the sustained elevation of myosin phosphorylation and tension in response to membrane depolarization.

[Osteoma originating in the dura: a case report]

We report a case of intracranial osteoma attached to the dura. The patient, a 35-year-old man, had suffered several episodes of vertigo over the previous two years. Physical and neurological findings on admission were unremarkable. A plain craniogram showed a dense calcified mass in the right frontal area, and CT revealed a homogeneous high-density mass without significant enhancement. MRI confirmed the dural origin of the lesion, which showed hyperintensity in the T1-weighted image and low intensity in the T2-weighted image. The mass was 5 cm in diameter and 2 cm in thickness. Total resection was performed under a preoperative diagnosis of calcified meningioma. Histopathology revealed the mass to be an osteoma. Osteomas are common benign bone tumors that usually arise from long bones of the extremities. Intracranial osteomas are extremely rare lesions. The literature on intracranial osteoma of dural origin is reviewed.

Rapid analysis of small samples containing forskolin using monoclonal antibodies

The effective range of the competitive ELISA test for detection of forskolin content in clonally propagated plant organs of Coleus forskohlii using monoclonal antibodies extends from 5ng to 5 micrograms. A correlation between the forskolin accumulation and the growth rate was investigated using the clonally propagated shoots. An increase of forskolin content was noted, beginning at week 6. Flowers, rachises, leaves, stems, tuberous roots, and roots were analyzed. Tuberous roots and the stem base contained higher amounts of forskolin than other organs. The forskolin content in the stem decreased gradually towards the top of the shoot.

Experimental study on autograft material for repair of round window rupture

The healing process following experimentally produced rupture of the round window (RW) and subsequent closure with autograft materials were investigated in guinea pigs. The covering materials studied were fascia and perichondrium, both of which were placed over the RW after extensive rupturing of the RW membrane. The grafts were observed 1, 2, and 3 months after the operation. No substantial difference in the results for the two materials could be discerned. They adhered to the surrounding bone and were incorporated into the RW membrane within 3 months.

Goldenhar's syndrome associated with anomalous internal auditory meatus

A case of Goldenhar's syndrome associated with fifth, seventh, and eighth nerve involvement is described. Tomographic examination of the temporal bones showed evidence of an abnormal internal auditory meatus. Otoneurological examination suggested that involvement of the seventh and eighth nerves was closely related to the abnormality in the internal auditory meatus.