Continuous ambulatory hand force monitoring during manual materials handling using instrumented force shoes and an inertial motion capture suit

Hand forces (HFs) are commonly measured during biomechanical assessment of manual materials handling; however, it is often a challenge to directly measure HFs in field studies. Therefore, in a previous study we proposed a HF estimation method based on ground reaction forces (GRFs) and body segment accelerations and tested it with laboratory equipment: GFRs were measured with force plates (FPs) and segment accelerations were measured using optical motion capture (OMC). In the current study, we evaluated the HF estimation method based on an ambulatory measurement system, consisting of inertial motion capture (IMC) and instrumented force shoes (FSs). Sixteen participants lifted and carried a 10-kg crate from ground level while 3D full-body kinematics were measured using OMC and IMC, and 3D GRFs were measured using FPs and FSs. We estimated 3D hand force vectors based on: (1) FP+OMC, (2) FP+IMC and (3) FS+IMC. We calculated the root-mean-square differences (RMSDs) between the estimated HFs to reference HFs calculated based on crate kinematics and the GRFs of a FP that the crate was lifted from. Averaged over subjects and across 3D force directions, the HF RMSD ranged between 10-15N when using the laboratory equipment (FP + OMC), 11-18N when using the IMC instead of OMC data (FP+IMC), and 17-21N when using the FSs in combination with IMC (FS + IMC). This error is regarded acceptable for the assessment of spinal loading during manual lifting, as it would results in less than 5% error in peak moment estimates.

Safety, efficacy and immunogenicity evaluation of the SAG2 oral rabies vaccine in Formosan ferret badgers

Since 2013, rabies cases have been reported among Formosan ferret badgers in Taiwan, and they have been shown to be the major reservoirs for Taiwanese enzootics. To control and eradicate rabies, the authorities plan to implement a vaccination programme. Before distributing live vaccines in the field, this study assessed the safety, efficacy, and immunogenicity of SAG2 vaccine on ferret badgers by direct oral instillation. After application of 109 TCID50/dose, no virus was excreted into the oral cavity 1-7 days post-application, and safety was also satisfactorily verified over a 266-day period. Moreover, despite the low level of rabies virus neutralising antibodies induced after vaccination of a 108 TCID50/dose, the efficacy assessment revealed a 100% survival rate (15/15) of vaccinees and an 87.5% fatality rate (7/8) in control animals after a challenge on the 198th day post-vaccination. The immunisation and protection rates obtained more than 6 months after a single vaccination dose demonstrated that SAG2 is an ideal vaccine candidate to protect Formosan ferret badgers against rabies in Taiwan.

A critical period for antidepressant-induced acceleration of neuronal maturation in adult dentate gyrus

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly used medications for mood and anxiety disorders, and adult neurogenesis in the dentate gyrus has been shown to be involved in the behavioral effects of SSRIs in mice. Studies have shown the varied effects of chronic treatment with SSRIs on adult neurogenesis. One such effect is the acceleration of neuronal maturation, which affects the functional integration of new neurons into existing neuronal circuitry. In this study, we labeled new neurons by using GFP-expressing retroviral vectors in mice and investigated the effect of an SSRI, fluoxetine, on these neurons at different time points after neuronal birth. Chronic treatment with fluoxetine accelerated the dendritic development of the newborn neurons and shifted the timing of the expression of the maturational marker proteins, doublecortin and calbindin. This accelerated maturation was observed even after sub-chronic treatment, only when fluoxetine was administered during the second week of neuronal birth. These results suggest the existence of a 'critical period' for the fluoxetine-induced maturation of new neurons. We propose that the modified functional integration of new neurons in the critical period may underlie the behavioral effects of fluoxetine by regulating anxiety-related decision-making processes.

[Analysis of the correlation between deep medullary veins and clinical prognosis of middle cerebral artery stroke]

Objective: To investigate the relativity between the distribution of deep medullary vein (DMV) in patients with middle cerebral artery stroke and clinical prognosis by using susceptibility-weighted imaging (SWI). Methods: A total of 144 cases of middle cerebral artery stroke patients and 55 healthy volunteers were retrospectively analyzed from January 2015 to October 2015 in order to investigate the symmetrical characteristic and the classification of DMV, then 30 cases were followed up. Kappa test was used to consider the consistency of judging DMV symmetry and type data by two radiologists. Results:Kappa value in DMV symmetry and DMV type were 0.875 and 0.852. Chi-square test analysis revealed a statistically significant difference of DMV symmetry between healthy control and stroke group(χ(2)=31.046, P=0.000). There was correlation between DMV type and NIHSS score in stroke group (r(s)=0.208, P=0.025). There was no statistically significant difference of DMV distribution in the different periods of stroke group (P=0.110). But there was statistically significant difference of DMV distribution between acute and chronic stroke (P=0.018). Among 30 follow-up cases, 18 cases with asymmetry DMV changed into symmetry after stroke therapy. In 8 cases with symmetry DMV, the diameter of DMV became smaller after treatment. In 4 cases, DMV had no changes. Conclusions: DMV in patients of MCA stroke are mostly asymmetry distribution. DMV classification can be used as an imaging standard to predict the prognosis of stroke patients.

[Preliminary study on assessment of lexiscan-induced blood-brain barrier opening and its level by CT perfusion imaging]

Objective: To evaluate the level of lexiscan-induced blood-brain barrier opening of healthy rabbits via CT perfusion weighted imaging (PWI) scan. Methods: Between November 2014 and May 2015, thirty New Zealand white rabbits were randomly assigned into three groups: the experimental group A1 which received one injection of lexiscan(1 ml/kg); the experimental group A2 which received three times injection of lexiscan(total dose: 1.5 ml/kg), finished within 15 minutes; the control group B which was injected the same volume normal saline(1 ml/kg), after 30 minutes, CT PWI scan was performed. Then cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and permeability surface(PS) of the region of interest of each group were acquired and compared statistically. Five cases of each group were injected with 2% Evans blue intravenously posterior to imaging. After one hour of infusion, all the animals were killed. Their brains were examined for the determination of Evans blue distribution. Results: Both the values of CBF and CBV and the staining with Evans blue of the group A1(CBF: (89.88±2.21), (81.42±4.28) ml·(100 g)^-1·min^-1; CBV: (3.97±0.43), (3.66±0.16) ml/g)and group A2 (CBF: (75.16±0.84), (63.66±7.21) ml·(100 g)^-1·min^-1; CBV: (4.07±0.01), (3.75±0.05) ml/g) were higher than those of the group B(CBF: (20.08±5.08), (14.58±8.62) ml·(100 g)^-1·min^-1; CBV: (0.85±0.04), (0.65±0.17) ml/g), the differences were all statistically significant (all P<0.01). While there was no statistically difference between group A1 and group A2(P>0.05). The value of PS of the group A2((22.43±8.09), (20.20±7.01)ml·(100 g)^-1·min^-1 )was higher than that of group A1((13.82±4.44), (10.12±2.44)ml·(100 g)^-1·min^-1) and group B(0.00, 0.00)(the lowest one), the differences were all statistically significant(all P<0.01). The value of MTT of the group A1((2.50±0.82, 2.47±0.10) s) had no statistical difference with group A2 and group B, while the value of group A2((4.50±0.17), (4.72±0.15) s) was higher than that of group B((1.88±0.09), (1.99±0.00) s), the differences were all statistically significant (P<0.05). Conclusion: Changes in hemodynamics of lexiscan-induced blood-brain barrier opening can be monitored by CT PWI scan. When the total dose of lexiscan increasing, the level of the BBB opening is higher with significantly increased CBF, CBV, PS and MTT.

Risk of infective endocarditis in patients with systemic lupus erythematosus in Taiwan: a nationwide population-based study

Objectives Patients with systemic lupus erythematosus are considered vulnerable to infective endocarditis and prophylactic antibiotics are recommended before an invasive dental procedure. However, the evidence is insufficient. This nationwide population-based study evaluated the risk and related factors of infective endocarditis in systemic lupus erythematosus. Methods We identified 12,102 systemic lupus erythematosus patients from the National Health Insurance research-oriented database, and compared the incidence rate of infective endocarditis with that among 48,408 non-systemic lupus erythematosus controls. A Cox multivariable proportional hazards model was employed to evaluate the risk of infective endocarditis in the systemic lupus erythematosus cohort. Results After a mean follow-up of more than six years, the systemic lupus erythematosus cohort had a significantly higher incidence rate of infective endocarditis (42.58 vs 4.32 per 100,000 person-years, incidence rate ratio = 9.86, p < 0.001) than that of the control cohort. By contrast, the older systemic lupus erythematosus cohort had lower risk (adjusted hazard ratio 11.64) than that of the younger-than-60-years systemic lupus erythematosus cohort (adjusted hazard ratio 15.82). Cox multivariate proportional hazards analysis revealed heart disease (hazard ratio = 5.71, p < 0.001), chronic kidney disease (hazard ratio = 2.98, p = 0.034), receiving a dental procedure within 30 days (hazard ratio = 36.80, p < 0.001), and intravenous steroid therapy within 30 days (hazard ratio = 39.59, p < 0.001) were independent risk factors for infective endocarditis in systemic lupus erythematosus patients. Conclusions A higher risk of infective endocarditis was observed in systemic lupus erythematosus patients. Risk factors for infective endocarditis in the systemic lupus erythematosus cohort included heart disease, chronic kidney disease, steroid pulse therapy within 30 days, and a recent invasive dental procedure within 30 days.

Modelling end-pumped passively Q-switched Nd-doped crystal lasers: manifestation by a Nd:YVO4/Cr4+:YAG system with a concave-convex resonator

A theoretical model for the passively Q-switched (PQS) operation which includes the spatial overlapping between the pump and lasing modes under the thermal lensing effect is developed to give a transcendental equation that can directly determine the critical parameters such as pulse energy, pulse repetition rate, and pulse width for the PQS performance. More importantly, an analytical function which gives the approximate solution for the transcendental equation as well as a specific critical criterion for good PQS operation are derived for practical analyses and design. A Nd:YVO₄/Cr⁴⁺:YAG system with a concave-convex resonator which can achieve fairly stable PQS pulse trains even at a high pump level is further exploited to manifest the proposed spatially dependent model. The good agreement between the experimental results and the theoretical predictions is verified to show the feasibility of the proposed model for designing high-power PQS lasers with high accuracy.

Generation of terahertz optical beating from a simultaneously self-mode-locked Nd:YAG laser at 1064 and 1123 nm

The reflectivity of the output coupler is designed to achieve the synchronously self-mode-locked operation at 1064 and 1123 nm in a diode-end-pumped Nd:YAG laser. Numerical analyses are performed to confirm that the designed output coupler can lead the emission lines to be predominant at 1064 and 1123 nm. Moreover, the crossover of the threshold pump powers for the 1064 and 1123 nm emission lines can be exploited to obtain the single central wavelength of 1064 nm or the single central wavelength of 1123 nm or, simultaneously, dual-central-wavelength self-mode-locked operation by finely adjusting the cavity alignment. For the dual-central-wavelength mode-locked emissions, the pulse repetition rate and the pulse duration are 4.5 GHz and 50.8 ps, respectively. The maximum output power can be up to 2.47 W at a pump power of 7.5 W. The synchronization of the 1064 and 1123 nm mode-locked pulses generates the optical beating pulse trains with repetition rates up to 14.7 THz.

Exploiting concave-convex linear resonators to design end-pumped solid-state lasers with flexible cavity lengths: Application for exploring the self-mode-locked operation

The characteristics of a convex-concave linear resonator under the thermal lensing effect are theoretically analyzed to find an analytical model for designing end-pumped solid-state lasers with flexible cavity lengths. By exploiting the design model, the power scaling for continuous-wave operation under strong thermal lensing can be easily achieved in the proposed resonator with different cavity lengths. Furthermore, the proposed resonator is applied to explore the exclusive influence of cavity length on the self-mode-locked (SML) operation. It is discovered that the lasing longitudinal modes will split into multiple groups in optical spectrum to lead to a multi-pulse mode-locked temporal state when the cavity length increases. Finally, a theoretical model is derived to reconstruct the experimental results of SML operation to deduce a simple relationship between the group number of lasing modes and the cavity length.

Characterization of tissue scaffolds for time-dependent biotransport criteria - a novel computational procedure

This study aims to establish a new computational framework that allows modeling transient oxygen diffusion in tissue scaffolds more efficiently. It has been well known that the survival of cells strongly relies on continuous oxygen/nutrient supply and metabolite removal. With optimal design in scaffold architecture, its ability to sustain long distance oxygen supply could be improved considerably. In this study, finite element based homogenization procedure is first used to characterize the initial effective biotransport properties in silico. These initial properties are proper indicators to prediction of the on-going performance of tissue scaffolds over time. The transient model by adopting an edge-based smoothed finite element method with combination of mass-redistributed method is then established to more efficiently simulate the transient oxygen transfer process in tissue scaffolds. The proposed new method allows large time steps to model the oxygen diffusion process without losing numerical accuracy, thereby enhancing the computational efficiency significantly, in particular for the design optimization problems which typically require numerous analysis iterations. A number of different scaffold designs are examined either under net diffusion without cell seeding, or under cellular oxygen/nutrient uptake with or without considering cell viability. The association between the homogenized effective diffusivity of net scaffold microstructures and corresponding transient diffusion and time-dependent cellular activities is divulged. This study provides some insights into scaffold design.

Estimating 3D L5/S1 moments and ground reaction forces during trunk bending using a full-body ambulatory inertial motion capture system

Inertial motion capture (IMC) systems have become increasingly popular for ambulatory movement analysis. However, few studies have attempted to use these measurement techniques to estimate kinetic variables, such as joint moments and ground reaction forces (GRFs). Therefore, we investigated the performance of a full-body ambulatory IMC system in estimating 3D L5/S1 moments and GRFs during symmetric, asymmetric and fast trunk bending, performed by nine male participants. Using an ambulatory IMC system (Xsens/MVN), L5/S1 moments were estimated based on the upper-body segment kinematics using a top-down inverse dynamics analysis, and GRFs were estimated based on full-body segment accelerations. As a reference, a laboratory measurement system was utilized: GRFs were measured with Kistler force plates (FPs), and L5/S1 moments were calculated using a bottom-up inverse dynamics model based on FP data and lower-body kinematics measured with an optical motion capture system (OMC). Correspondence between the OMC+FP and IMC systems was quantified by calculating root-mean-square errors (RMSerrors) of moment/force time series and the interclass correlation (ICC) of the absolute peak moments/forces. Averaged over subjects, L5/S1 moment RMSerrors remained below 10Nm (about 5% of the peak extension moment) and 3D GRF RMSerrors remained below 20N (about 2% of the peak vertical force). ICCs were high for the peak L5/S1 extension moment (0.971) and vertical GRF (0.998). Due to lower amplitudes, smaller ICCs were found for the peak asymmetric L5/S1 moments (0.690-0.781) and horizontal GRFs (0.559-0.948). In conclusion, close correspondence was found between the ambulatory IMC-based and laboratory-based estimates of back load.

Pulmonary Cryptococcosis

Inhalation of Cryptococcus into the respiratory system is the main route of acquisition of human infection, yet pulmonary cryptococcosis goes mostly unrecognized by many clinicians. This delay in diagnosis, or misdiagnosis, of lung infections is due in part to frequently subtle clinical manifestations such as a subacute or chronic cough, a broad differential of diagnostic possibilities for associated pulmonary masses (cryptococcomas) and, on occasion, negative respiratory tract cultures. Hematogenous dissemination from the lung can result in protean manifestations, the most severe of which is meningoencephalitis. There are few clinical studies of pulmonary cryptococcosis and its pathogenesis is poorly understood. The main purpose of this review is to describe the epidemiology, clinical presentation, diagnosis, and treatment of pulmonary cryptococcosis to increase clinician's awareness of this diagnostic possibility and to enhance clinical management. Useful pointers to the approach and management of pulmonary cryptococcosis and the implications of disseminated disease are included, together with recommendations for future research.

Introduction to the updated Australian and New Zealand consensus guidelines for the use of antifungal agents in the haematology/oncology setting, 2014

This article introduces the second revision of the Australian and New Zealand consensus guidelines for the use of antifungal agents in the haematology/oncology setting. The current update occurs within the context of a growing population at risk of invasive fungal disease, improved understanding of risk factors, availability of new diagnostic tests, a much-expanded evidence base and changing clinical paradigms. Here, we provide an overview of the history and purpose of the guidelines, including changes in scope since the last clinical update was published in 2008. The process for development, and for enabling review of draft recommendations by end-users and other relevant stakeholders, is described. The approach to assigning levels of evidence and grades of recommendation is also provided, along with a comparison to international grading systems.

Consensus guidelines for the treatment of yeast infections in the haematology, oncology and intensive care setting, 2014

Pathogenic yeast forms are commonly associated with invasive fungal disease in the immunocompromised host, including patients with haematological malignancies and patients of haemopoietic stem cell transplants. Yeasts include the Candida spp., Cryptococcus spp., Pneumocystis jirovecii and some lesser-known pathogens. Candida species remain the most common cause of invasive yeast infections (and the most common human pathogenic fungi). These guidelines present evidence-based recommendations for the antifungal management of established, invasive yeast infections in adult and paediatric patients in the haematology/oncology setting. Consideration is also given to the critically ill patient in intensive care units, including the neonatal intensive care unit. Evidence for 'pre-emptive' or 'diagnostic-driven antifungal therapy' is also discussed. For the purposes of this paper, invasive yeast diseases are categorised under the headings of invasive candidiasis, cryptococcosis and uncommon yeast infections. Specific recommendations for the management of Pneumocystis jirovecii are presented in an accompanying article (see consensus guidelines by Cooley et al. appearing elsewhere in this supplement).

Consensus guidelines for implementation of quality processes to prevent invasive fungal disease and enhanced surveillance measures during hospital building works, 2014

Healthcare-associated fungal outbreaks impose a substantial economic burden on the health system and typically result in high patient morbidity and mortality, particularly in the immunocompromised host. As the population at risk of invasive fungal infection continues to grow due to the increased burden of cancer and related factors, the need for hospitals to employ preventative measures has become increasingly important. These guidelines outline the standard quality processes hospitals need to accommodate into everyday practice and at times of healthcare-associated outbreak, including the role of antifungal stewardship programmes and best practice environmental sampling. Specific recommendations are also provided to help guide the planning and implementation of quality processes and enhanced surveillance before, during and after high-risk activities, such as hospital building works. Areas in which information is still lacking and further research is required are also highlighted.

Intracavity continuous-wave multiple stimulated-Raman-scattering emissions in a KTP crystal pumped by a Nd:YVO(4) laser

Intracavity continuous-wave (CW) multiple stimulated-Raman-scattering emissions have been successfully demonstrated in a KTP crystal pumped by a Nd:YVO(4) 1064-nm laser for the first time. Three different output couplers (OCs) with high-reflection (HR) coating in the range of 1-1.1, 1-1.13, and 1-1.15 μm are employed in the experiment to generate lasing wavelengths at 1095 (the first-Stokes emission of the 266 cm(-1) Raman shift), 1095 + 1128 (the first- and second-Stokes emission of the 266 cm(-1) Raman shift), and 1095 + 1128 + 1149 nm (the first two Stokes emissions of the 266 cm(-1) Raman shift and the first-Stokes emission of the 694 cm(-1) Raman shift), separately. This Raman laser paves a way to produce more-closely spaced set of CW emission in the green-yellow region.

Cryogenically monolithic self-Raman lasers: observation of single-longitudinal-mode operation

A cryogenically monolithic Nd:YVO4 self-Raman laser is experimentally explored and theoretically analyzed. The variation of the stimulated Raman scattering (SRS) threshold on the temperature is found to be nonlinear because the reduction of thermal lensing enlarges the cavity mode size. In spite of the nonlinear variation of the SRS threshold on the temperature, the overall SRS output power can be efficiently increased from 0.78 to 1.36 W for temperature decreasing from 285 to 80 K at an absorbed power of 17.2 W. More interestingly, the single-longitudinal-mode operation is experimentally achieved when temperature is lower than 125 K.

24-W cryogenically cooled Nd:YAG monolithic 946-nm laser with a slope efficiency >70

A high-power efficient monolithic Nd:YAG 946-nm laser is demonstrated at the cryogenic temperature. By exploring the absorption and the fluorescence spectra of the Nd:YAG crystal, it reveals the fact that the absorption bandwidth at 808 nm is narrowing and the fluorescence intensity at 1061 nm is significant enhanced when the temperature is decreased. The temperature dependence of the lasing threshold at 946 nm is found to display a minimum value near a temperature of 170 K. At an incident pump power of 34.5 W, the local heating leads the optimum temperature to be approximately 120 K and the maximum output power can reach 24.4 W with the conversion efficiency of 71% as well as the slope efficiency up to 75%.

Assessment of autonomic nervous system by using empirical mode decomposition-based reflection wave analysis during non-stationary conditions

Arterial blood pressure (ABP) is an important indicator of cardiovascular circulation and presents various intrinsic regulations. It has been found that the intrinsic characteristics of blood vessels can be assessed quantitatively by ABP analysis (called reflection wave analysis (RWA)), but conventional RWA is insufficient for assessment during non-stationary conditions, such as the Valsalva maneuver. Recently, a novel adaptive method called empirical mode decomposition (EMD) was proposed for non-stationary data analysis. This study proposed a RWA algorithm based on EMD (EMD-RWA). A total of 51 subjects participated in this study, including 39 healthy subjects and 12 patients with autonomic nervous system (ANS) dysfunction. The results showed that EMD-RWA provided a reliable estimation of reflection time in baseline and head-up tilt (HUT). Moreover, the estimated reflection time is able to assess the ANS function non-invasively, both in normal, healthy subjects and in the patients with ANS dysfunction. EMD-RWA provides a new approach for reflection time estimation in non-stationary conditions, and also helps with non-invasive ANS assessment.

Separated response function ratios in exclusive, forward π(±) electroproduction

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6  GeV(2) at W=1.95  GeV, and Q(2)=2.45  GeV(2) at W=2.22  GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.

Postoperative adverse outcomes after non-hepatic surgery in patients with liver cirrhosis

BACKGROUND

Postoperative adverse outcomes in patients with liver cirrhosis are not completely understood. This study evaluated the association between liver cirrhosis and adverse outcomes after non-hepatic surgery.

METHODS

Reimbursement claims were used to identify patients with preoperative liver cirrhosis who underwent non-hepatic surgery from 2004 to 2007. Control patients without cirrhosis were matched by age, sex, type of surgery and anaesthesia. The adjusted odds ratios (ORs) and 95 per cent confidence intervals (c.i.) of postoperative adverse events associated with liver cirrhosis were analysed by multivariable logistic regression.

RESULTS

Thirty-day mortality rates among 24 282 patients with cirrhosis and 97 128 control patients were 1·2 per cent (299 deaths) and 0·7 per cent (635 deaths) respectively. Liver cirrhosis was associated with postoperative 30-day mortality (OR 1·88, 95 per cent c.i. 1·63 to 2·16), acute renal failure (OR 1·52, 1·34 to 1·74), septicaemia (OR 1·42, 1·33 to 1·51) and intensive care unit admission (OR 1·39, 1·33 to 1·45). Postoperative mortality increased in patients who had liver cirrhosis with viral hepatitis (OR 2·87, 1·55 to 5·30), alcohol dependence syndrome (OR 3·74, 2·64 to 5·31), jaundice (OR 5·47, 3·77 to 7·93), ascites (OR 5·85, 4·62 to 7·41), gastrointestinal haemorrhage (OR 3·01, 2·33 to 3·90) and hepatic coma (OR 5·11, 3·79 to 6·87).

CONCLUSION

Patients with liver cirrhosis had increased mortality and complications after non-hepatic surgery, particularly those with cirrhosis-related clinical indicators.

PPARα-mediated responses in human adult liver stem cells: In vivo/in vitro and cross-species comparisons

The peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor that regulates a variety of biological processes including lipid metabolism and energy homeostasis. Peroxisome proliferators (PPs) are carcinogens in rodents, while humans are resistant to peroxisome proliferation and carcinogenesis. In this study, we examined the differential gene expression elicited by clofibrate (CLO) and WY-14,643 (WY) in C57BL/6 mouse liver compared to responses in human HepG2 hepatoma and HL1-1 adult stem cells. Mice were gavaged with sesame oil, 300mg/kg CLO or WY for 2, 4, 8, 12, 18 or 24h, or daily for 4 or 14 days. Although no significant changes in body weight gain were observed, WY induced relative liver weight at 4 and 14 days. Genome-wide hepatic gene expression analysis identified 719 and 1443 differentially expressed unique genes elicited by CLO and WY, respectively (|fold change|>1.5, P1(t)>0.99). Functional analysis associated the gene expression changes with lipid metabolism, transport, cell cycle and immune response. Most differentially expressed genes were in common to both treatments and clustered together only at early time points (2-8h). Complementary QRT-PCR studies in human HL1-1 and HepG2 cells treated with 50μM WY or DMSO for 1, 2, 4, 8, 12, 24 or 48h identified a minimal number of conserved orthologous responses (e.g., Pdk4, Adfp and Angptl4) while some genes (i.e., Bmf, a tumor suppressor) exhibited induction in human cells but repression in mice. These data suggest that PPs elicit species-specific PPARα-mediated gene expression.