Piperine Induces Hepatic Low-Density Lipoprotein Receptor Expression through Proteolytic Activation of Sterol Regulatory Element-Binding Proteins

Elevated plasma low-density lipoprotein (LDL) cholesterol is considered as a risk factor for atherosclerosis. Because the hepatic LDL receptor (LDLR) uptakes plasma lipoproteins and lowers plasma LDL cholesterol, the activation of LDLR is a promising drug target for atherosclerosis. In the present study, we identified the naturally occurring alkaloid piperine, as an inducer of LDLR gene expression by screening the effectors of human LDLR promoter. The treatment of HepG2 cells with piperine increased LDLR expression at mRNA and protein levels and stimulated LDL uptake. Subsequent luciferase reporter gene assays revealed that the mutation of sterol regulatory element-binding protein (SREBP)-binding element abolished the piperine-mediated induction of LDLR promoter activity. Further, piperine treatments increased mRNA levels of several SREBP targets and mature forms of SREBPs. However, the piperine-mediated induction of the mature forms of SREBPs was not observed in SRD–15 cells, which lack insulin-induced gene–1 (Insig–1) and Insig–2. Finally, the knockdown of SREBPs completely abolished the piperine-meditated induction of LDLR gene expression in HepG2 cells, indicating that piperine stimulates the proteolytic activation of SREBP and subsequent induction of LDLR expression and activity.     

Renal Function Outcomes and Risk Factors for Risk Factors for Stage 3B Chronic Kidney Disease after Urinary Diversion in Patients with Muscle Invasive Bladder Cancer

ObjectivesTo assess the effects of urinary diversion on renal function, we retrospectively investigated renal function over 5 years after urinary diversion using a propensity score matching strategy.MethodsBetween May 1996 and November 2013, 345 consecutive adult patients underwent radical cystectomy and urinary diversion in our hospital; one hundred and fifteen patients with more than a 5-year follow-up were enrolled. Propensity scores were calculated using logistic analysis, and the data used in the analyses included age, gender, Eastern Cooperative Oncology Group Performance Status (ECOG-PS), clinical tumor stage, presence of cardiovascular disease; hypertension; and type 2 diabetes and preoperative eGFR at the initial visit. Multivariate logistic regression analysis was used to assess the risk factors for stage 3B chronic kidney disease (CKD) after the different types of urinary diversion.ResultsContinent and incontinent diversion were performed in 68 and 47 patients, respectively. The mean preoperative eGFR was significantly lower in the incontinent than in the continent group (P < 0.001). In propensity score-matched patients (n = 34 each), no significant differences were observed in pre- and postoperative eGFR and 5-year eGFR decrease rates between the groups. In the incontinent group, the number of postoperative stage 3B CKD patients was significantly increased than the continent group. Using multivariate analysis, independent risk factors significantly associated with stage 3B CKD at 5 years after surgery were older age, eGFR before surgery, incontinent diversion (cutaneous ureterostomy), and postoperative hydronephrosis.ConclusionsThe types of urinary diversion had no significant impact on renal function decline, whereas older age, preexisting impaired renal function, postoperative hydronephrosis, and cutaneous ureterostomy were independent risk factors for stage 3B CKD at 5 years after radical cystectomy.     

Dynamics of light-induced conformational changes of the phoborhodopsin/transducer complex formed in the n-dodecyl beta-D-maltoside micelle

A complex of photoreceptor phoborhodopsin (ppR; also called sensory rhodopsin II) and its cognate halobacterial transducer II (pHtrII) existing in the plasma membrane mediates the light signal to the cytoplasm in the earliest step of negative phototaxis in Natronomonas pharaonis. We have investigated the dynamics of the light-induced conformational changes of the ppR/pHtrII(1-159) complex formed in the presence of 0.1% n-dodecyl beta-d-maltoside (DDM) by a fluorescence resonance energy transfer (FRET) based method. Fluorescence donor and acceptor dyes were linked to cysteine residues genetically introduced at given positions in pHtrII and ppR. The light-induced FRET efficiency changes for various pairs of dye-labeled cysteine residues were determined to examine dynamics of movements of given residues in the transmembrane and the linker region including the HAMP domain in pHtrII induced by photoexcitation of ppR. Upon flash excitation of ppR, FRET efficiency changed depending on pairs of the labeled cysteine residues. The distances between V185 in ppR and the five given residues (102 through 141) in the pHtrII linker region estimated from the FRET efficiency increased by 0.3-0.8 A; on the other hand, the distances between S31 in ppR and the five residues in pHtrII decreased. The changes arose within 70 ms (the dead time of instrument) and decayed at a rate of 1.1 +/- 0.2 s. Azide significantly increased the decay rate of light-induced FRET efficiency changes by accelerating the decay of the M state of ppR. The decay rate of FRET efficiency changes coincided with the rate of recovery of the ppR to the initial state but not the decay of the M state. We conclude that the light-induced conformational change of pHtrII occurs before, at the formation or during the M state, and its relaxation is coupled tightly with the decay of the O state of ppR in the 1:1 complex formed in the DDM micelle.     

Role of IGF signaling in catch-up growth and accelerated temporal development in zebrafish embryos in response to oxygen availability

Animals respond to adverse environments by slowing down or arresting growth and development. Upon returning to normal conditions, they often show compensatory acceleration in growth and developmental rate. This phenomenon, known as `catch-up' growth, is widely documented in the animal kingdom. The underlying molecular mechanisms, however, are poorly understood. Using the zebrafish embryo as an experimental model system, we tested the hypothesis that changes in IGF signaling activities play an important role in the accelerated growth and temporal development resulting from re-oxygenation following hypoxia. We show that chronic hypoxia reduced, and re-oxygenation accelerated, embryonic growth and developmental rate. Whereas hypoxia repressed the Igf1 receptor and its downstream Erk1/2 and Akt signaling activities, re-oxygenation restored their activities. Specific inhibition of Igf1 receptor signaling during re-oxygenation by genetic and pharmacological approaches attenuated catch-up growth. Further analysis showed that whereas PI3K-Akt is required in both normal and catch-up growth, Mek1/2-Erk1/2 activation induced by elevated IGF signaling during re-oxygenation is particularly crucial for catch-up growth. These results suggest that the evolutionarily conserved IGF signaling pathway coordinates growth and temporal development in zebrafish embryos in response to oxygen availability.     

Responses to Apical and Basolateral Application of Glutamate in Mouse Fungiform Taste Cells with Action Potentials

In taste bud cells, glutamate may elicit two types of responses, as an umami tastant and as a neurotransmitter. Glutamate applied to apical membrane of taste cells would elicit taste responses whereas glutamate applied to basolateral membrane may act as a neurotransmitter. Using restricted stimulation to apical or basolateral membrane of taste cells, we examined responses of taste cells to glutamate stimulation, separately. Apical application of monosodium glutamate (MSG, 0.3 M) increased firing frequency in some of mouse fungiform taste cells that evoked action potentials. These cells were tested with other basic taste compounds, NaCl (salty), saccharin (sweet), HCl (sour), and quinine (bitter). MSG-sensitive taste cells could be classified into sweet-best (S-type), MSG-best (M-type), and NaCl or other electrolytes-best (N- or E/H-type) cells. Furthermore, S- and M-type could be classified into two sub-types according to the synergistic effect between MSG and inosine-5′-monophosphate (S1, M1 with synergism; S2, M2 without synergism). Basolateral application of glutamate (100 μM) had almost no effect on the mean spontaneous firing rates in taste cells. However, about 10% of taste cells tested showed transient increases in spontaneous firing rates (>mean + 2 standard deviation) after basolateral application of glutamate. These results suggest the existence of multiple types of umami-sensitive taste cells and the existence of glutamate receptor(s) on the basolateral membrane of a subset of taste cells.     

Glucose Homeostatic Law: Insulin Clearance Predicts the Progression of Glucose Intolerance in Humans

Homeostatic control of blood glucose is regulated by a complex feedback loop between glucose and insulin, of which failure leads to diabetes mellitus. However, physiological and pathological nature of the feedback loop is not fully understood. We made a mathematical model of the feedback loop between glucose and insulin using time course of blood glucose and insulin during consecutive hyperglycemic and hyperinsulinemic-euglycemic clamps in 113 subjects with variety of glucose tolerance including normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM). We analyzed the correlation of the parameters in the model with the progression of glucose intolerance and the conserved relationship between parameters. The model parameters of insulin sensitivity and insulin secretion significantly declined from NGT to IGT, and from IGT to T2DM, respectively, consistent with previous clinical observations. Importantly, insulin clearance, an insulin degradation rate, significantly declined from NGT, IGT to T2DM along the progression of glucose intolerance in the mathematical model. Insulin clearance was positively correlated with a product of insulin sensitivity and secretion assessed by the clamp analysis or determined with the mathematical model. Insulin clearance was correlated negatively with postprandial glucose at 2h after oral glucose tolerance test. We also inferred a square-law between the rate constant of insulin clearance and a product of rate constants of insulin sensitivity and secretion in the model, which is also conserved among NGT, IGT and T2DM subjects. Insulin clearance shows a conserved relationship with the capacity of glucose disposal among the NGT, IGT and T2DM subjects. The decrease of insulin clearance predicts the progression of glucose intolerance.     

Association between delayed bedtime and sleep-related problems among community-dwelling 2-year-old children in Japan

Background

Although delayed sleep timing causes many socio-psycho-biological problems such as sleep loss, excessive daytime sleepiness, obesity, and impaired daytime neurocognitive performance in adults, there are insufficient data showing the clinical significance of a ‘night owl lifestyle’ in early life. This study examined the association between habitual delayed bedtime and sleep-related problems among community-dwelling 2-year-old children in Japan.

Methods

Parents/caregivers of 708 community-dwelling 2-year-old children in Nishitokyo City, Tokyo, participated in the study. The participants answered a questionnaire to evaluate their child’s sleep habits and sleep-related problems for the past 1 month.

Results

Of the 425 children for whom complete data were collected, 90 (21.2%) went to bed at 22:00 or later. Children with delayed bedtime showed significantly more irregular bedtime, delayed wake time, shorter total sleep time, and difficulty in initiating and terminating sleep. Although this relationship indicated the presence of sleep debt in children with delayed bedtime, sleep onset latency did not differ between children with earlier bedtime and those with delayed bedtime. Rather, delayed bedtime was significantly associated with bedtime resistance and problems in the morning even when adjusting for nighttime and daytime sleep time.

Conclusions

Even in 2-year-old children, delayed bedtime was associated with various sleep-related problems. The causal factors may include diminished homeostatic sleep drive due to prolonged daytime nap as well as diurnal preference (morning or night type) regulated by the biological clock.     

Evaluation of two-dimensional electronic portal imaging device using integrated images during volumetric modulated arc therapy for prostate cancer

BackgroundThe aim of the study was to evaluate analysis criteria for the identification of the presence of rectal gas during volumetric modulated arc therapy (VMAT) for prostate cancer patients by using electronic portal imaging device (EPID)-based in vivo dosimetry (IVD).Materials and methodsAll measurements were performed by determining the cumulative EPID images in an integrated acquisition mode and analyzed using PerFRACTION commercial software. Systematic setup errors were simulated by moving the anthropomorphic phantom in each translational and rotational direction. The inhomogeneity regions were also simulated by the I’mRT phantom attached to the Quasar phantom. The presence of small and large air cavities (12 and 48 cm³) was controlled by moving the Quasar phantom in several timings during VMAT. Sixteen prostate cancer patients received EPID-based IVD during VMAT.ResultsIn the phantom study, no systematic setup error was detected in the range that can happen in clinical (< 5-mm and < 3 degree). The pass rate of 2% dose difference (DD2%) in small and large air cavities was 98.74% and 79.05%, respectively, in the appearance of the air cavity after irradiation three quarter times. In the clinical study, some fractions caused a sharp decline in the DD2% pass rate. The proportion for DD2% < 90% was 13.4% of all fractions. Rectal gas was confirmed in 11.0% of fractions by acquiring kilo-voltage X-ray images after the treatment.ConclusionsOur results suggest that analysis criteria of 2% dose difference in EPID-based IVD was a suitable method for identification of rectal gas during VMAT for prostate cancer patients.     

Essential roles of high-mobility group box 1 in the development of murine colitis and colitis-associated cancer

High-mobility group box 1 (HMGB1) is a nuclear factor released extracellularly as a proinflammatory cytokine. We measured the HMGB1 concentration in the sera of mice with chemically induced colitis (DSS; dextran sulfate sodium salt) and found a marked increase. Inhibition of HMGB1 by neutralizing anti-HMGB1 antibody resulted in reduced inflammation in DSS-treated colons. In macrophages, HMGB1 induces several proinflammatory cytokines, such as IL-6, which are regulated by NF-kappaB activation. Two putative sources of HMGB1 were explored: in one, bacterial factors induce HMGB1 secretion from macrophages and in the other, necrotic epithelial cells directly release HMGB1. LPS induced a small amount of HMGB1 in macrophages, but macrophages incubated with supernatant prepared from necrotic cells and containing large amounts of HMGB1 activated NF-kappaB and induced IL-6. Using the colitis-associated cancer model, we demonstrated that neutralizing anti-HMGB1 antibody decreases tumor incidence and size. These observations suggest that HMGB1 is a potentially useful target for IBD treatment and the prevention of colitis-associated cancer.