Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis

Regulation of shear-induced nuclear translocation of the Nrf2 transcription factor in endothelial cells

<p>Abstract</p> <p>Background</p> <p>Vascular endothelial cells (ECs) constantly experience fluid shear stresses generated by blood flow. Laminar flow is known to produce atheroprotective effects on ECs. Nrf2 is a transcription factor that is essential for the antioxidant response element (ARE)-mediated induction of genes such as heme-oxygenase 1 (HO-1). We previously showed that fluid shear stress increases intracellular reactive oxygen species (ROS) in ECs. Moreover, oxidants are known to stimulate Nrf2. We thus examined the regulation of Nrf2 in cultured human ECs by shear stress.</p> <p>Results</p> <p>Exposure of human umbilical vein endothelial cells (HUVECs) to laminar shear stress (12 dyne/cm²) induced Nrf2 nuclear translocation, which was inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor, a protein kinase C (PKC) inhibitor, and an antioxidant agent N-acetyl cysteine (NAC), but not by other protein kinase inhibitors. Therefore, PI3K, PKC, and ROS are involved in the signaling pathway that leads to the shear-induced nuclear translocation of Nrf2. We also found that shear stress increased the ARE-binding activity of Nrf2 and the downstream expression of HO-1.</p> <p>Conclusion</p> <p>Our data suggest that the atheroprotective effect of laminar flow is partially attributed to Nrf2 activation which results in ARE-mediated gene transcriptions, such as HO-1 expression, that are beneficial to the cardiovascular system.</p

Japanese encephalitis virus induces matrix metalloproteinase-9 expression via a ROS/c-Src/PDGFR/PI3K/Akt/MAPKs-dependent AP-1 pathway in rat brain astrocytes

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis virus (JEV) infection is a major cause of acute encephalopathy in children, which destroys central nervous system (CNS) cells, including astrocytes and neurons. Matrix metalloproteinase (MMP)-9 has been shown to degrade components of the basal lamina, leading to disruption of the blood-brain barrier (BBB) and to contribute to neuroinflammatory responses in many neurological diseases. However, the detailed mechanisms of JEV-induced MMP-9 expression in rat brain astrocytes (RBA-1 cells) are largely unclear.</p> <p>Methods</p> <p>In this study, the effect of JEV on expression of MMP-9 was determined by gelatin zymography, western blot analysis, RT-PCR, and promoter assay. The involvement of AP-1 (c-Jun and c-Fos), c-Src, PDGFR, PI3K/Akt, and MAPKs in these responses were investigated by using the selective pharmacological inhibitors and transfection with siRNAs.</p> <p>Results</p> <p>Here, we demonstrate that JEV induces expression of pro-form MMP-9 via ROS/c-Src/PDGFR/PI3K/Akt/MAPKs-dependent, AP-1 activation in RBA-1 cells. JEV-induced MMP-9 expression and promoter activity were inhibited by pretreatment with inhibitors of AP-1 (tanshinone), c-Src (PP1), PDGFR (AG1296), and PI3K (LY294002), and by transfection with siRNAs of c-Jun, c-Fos, PDGFR, and Akt. Moreover, JEV-stimulated AP-1 activation was inhibited by pretreatment with the inhibitors of c-Src, PDGFR, PI3K, and MAPKs.</p> <p>Conclusion</p> <p>From these results, we conclude that JEV activates the ROS/c-Src/PDGFR/PI3K/Akt/MAPKs pathway, which in turn triggers AP-1 activation and ultimately induces MMP-9 expression in RBA-1 cells. These findings concerning JEV-induced MMP-9 expression in RBA-1 cells imply that JEV might play an important role in CNS inflammation and diseases.</p

Renal Protection for Coronary Angiography in Advanced Renal Failure Patients by Prophylactic Hemodialysis A Randomized Controlled Trial

ObjectivesWe performed a study to determine whether prophylactic hemodialysis reduces contrast nephropathy (CN) after coronary angiography in advanced renal failure patients.BackgroundPre-existing renal failure is the greatest risk factor for CN. Hemodialysis can effectively remove contrast media, but its effect upon preventing CN is still uncertain.MethodsEighty-two patients with chronic renal failure, referred for coronary angiography, were assigned randomly to receive either normal saline intravenously and prophylactic hemodialysis (dialysis group; n = 42) or fluid supplement only (control group; n = 40).ResultsProphylactic hemodialysis lessened the decrease in creatinine clearance within 72 h in the dialysis group (0.4 ± 0.9 ml/min/1.73 m2vs. 2.2 ± 2.8 ml/min/1.73 m2; p < 0.001). Compared with the dialysis group, the serum creatinine concentrations in the control group were significantly higher at day 4 (6.3 ± 2.3 mg/dl vs. 5.1 ± 1.3 mg/dl; p = 0.010) and at peak level (6.7 ± 2.7 mg/dl vs. 5.3 ± 1.5 mg/dl; p = 0.005). Temporary renal replacement therapy was required in 35% of the control patients and in 2% of the dialysis group (p < 0.001). Thirteen percent of the control patients, but none of the dialysis patients, required long-term dialysis after discharge (p = 0.018). For the patients not requiring chronic dialysis, 13 patients in the control group (37%) and 2 in the dialysis group (5%) had an increase in serum creatinine concentration at discharge of more than 1 mg/dl from baseline (p < 0.001).ConclusionsProphylactic hemodialysis is effective in improving renal outcome in chronic renal failure patients undergoing coronary angiography

Frequency Dependent Alterations in Regional Homogeneity of Baseline Brain Activity in Schizophrenia

Low frequency oscillations are essential in cognitive function impairment in schizophrenia. While functional connectivity can reveal the synchronization between distant brain regions, the regional abnormalities in task-independent baseline brain activity are less clear, especially in specific frequency bands. Here, we used a regional homogeneity (ReHo) method combined with resting-state functional magnetic resonance imaging to investigate low frequency spontaneous neural activity in the three different frequency bands (slow-5:0.01–0.027 Hz; slow-4:0.027–0.08 Hz; and typical band: 0.01–0.08 Hz) in 69 patients with schizophrenia and 62 healthy controls. Compared with controls, schizophrenia patients exhibited decreased ReHo in the precentral gyrus, middle occipital gyrus, and posterior insula, whereas increased ReHo in the medial prefrontal cortex and anterior insula. Significant differences in ReHo between the two bands were found in fusiform gyrus and superior frontal gyrus (slow-4> slow-5), and in basal ganglia, parahippocampus, and dorsal middle prefrontal gyrus (slow-5> slow-4). Importantly, we identified significant interaction between frequency bands and groups in the inferior occipital gyrus and caudate body. This study demonstrates that ReHo changes in schizophrenia are widespread and frequency dependent

Clonal dissemination of invasive and colonizing clonal complex 1 of serotype VI group B Streptococcus in central Taiwan

Background/PurposeThe aim of this study was to investigate clinical presentation, serotype distribution and genetic correlation of group B streptococcus (GBS) diseases. Since serotype VI prevalence far exceeded that reported in prior studies, genetic relationship of isolates was further analyzed.MethodsGBS isolates obtaining from patients with invasive diseases and pregnant women with colonization between June 2007 and December 2010 were analyzed. All isolates were tested for serotypes by multiplex PCR assay and pulsed-field gel electrophoresis (PFGE). Serotype VI isolates were further analyzed by multilocus sequence typing (MLST).ResultsA total of 134 GBS isolates were recovered from blood of 126 patients with invasive disease (94.0%) and anogenital swabs of 8 pregnant women (6.0%). Most common serotype was Ib (21.6%), followed by V (20.1%), VI (18.7%), III (15.7%), II (11.9 %), Ia (11.2%), and IX (0.7%). Serotype VI was also the leading type in infants with early onset disease (EOD; 3/8, 37.5%) and colonizing pregnant women (3/8, 37.5%). PFGE distinguished 33 pulsotypes, reflecting genetic diversity among GBS isolates. Among 25 serotype VI isolates tested, 14 were ST-1, seven were ST-679, three were ST-678, one was ST-681, and distributed into four PFGE pulsotypes. ST-678, ST-679, and ST-681 were novel sequence types; ST-678 and ST-679 are single-locus variants of ST-1 that belongs to clonal complex (CC) 1.ConclusionCC1 dissemination of serotype VI GBS thus emerges as an important invasive pathogen in infants and nonpregnant adults in central Taiwan. Serotype prevalence of GBS must be continuously monitored geographically to guide prevention strategy of GBS vaccines

An overview of the Phalaenopsis orchid genome through BAC end sequence analysis

<p>Abstract</p> <p>Background</p> <p><it>Phalaenopsis </it>orchids are popular floral crops, and development of new cultivars is economically important to floricultural industries worldwide. Analysis of orchid genes could facilitate orchid improvement. Bacterial artificial chromosome (BAC) end sequences (BESs) can provide the first glimpses into the sequence composition of a novel genome and can yield molecular markers for use in genetic mapping and breeding.</p> <p>Results</p> <p>We used two BAC libraries (constructed using the <it>Bam</it>HI and <it>Hin</it>dIII restriction enzymes) of <it>Phalaenopsis equestris </it>to generate pair-end sequences from 2,920 BAC clones (71.4% and 28.6% from the <it>Bam</it>HI and <it>Hin</it>dIII libraries, respectively), at a success rate of 95.7%. A total of 5,535 BESs were generated, representing 4.5 Mb, or about 0.3% of the <it>Phalaenopsis </it>genome. The trimmed sequences ranged from 123 to 1,397 base pairs (bp) in size, with an average edited read length of 821 bp. When these BESs were subjected to sequence homology searches, it was found that 641 (11.6%) were predicted to represent protein-encoding regions, whereas 1,272 (23.0%) contained repetitive DNA. Most of the repetitive DNA sequences were gypsy- and copia-like retrotransposons (41.9% and 12.8%, respectively), whereas only 10.8% were DNA transposons. Further, 950 potential simple sequence repeats (SSRs) were discovered. Dinucleotides were the most abundant repeat motifs; AT/TA dimer repeats were the most frequent SSRs, representing 253 (26.6%) of all identified SSRs. Microsynteny analysis revealed that more BESs mapped to the whole-genome sequences of poplar than to those of grape or <it>Arabidopsis</it>, and even fewer mapped to the rice genome. This work will facilitate analysis of the <it>Phalaenopsis </it>genome, and will help clarify similarities and differences in genome composition between orchids and other plant species.</p> <p>Conclusion</p> <p>Using BES analysis, we obtained an overview of the <it>Phalaenopsis </it>genome in terms of gene abundance, the presence of repetitive DNA and SSR markers, and the extent of microsynteny with other plant species. This work provides a basis for future physical mapping of the <it>Phalaenopsis </it>genome and advances our knowledge thereof.</p

Trajectory of low-density lipoprotein cholesterol in patients with chronic kidney disease and its association with cardiovascular disease

BackgroundThe role of longitudinal temporal trends in LDL-C in cardiovascular disease (CVD) in patients with chronic kidney disease (CKD) and diabetes is unclear. This study categorized the long-term LDL-C trajectory and determined its association with the incidence of atherosclerotic CVD in patients with CKD according to diabetes status and estimated glomerular filtration rate (eGFR).MethodsThe risk of atherosclerotic CVD was estimated in 137,127 Taiwanese patients with CKD using six LDL-C trajectory classes determined by the latent class mixed model as optimal, near optimal, above optimal, borderline, sustained high, and declined high over 5 years.ResultsThe risk of CVD was higher in the sustained high LDL-C [&gt;160 mg/dL over time; adjusted hazard ratio (aHR) = 1.68, 95% CI = 1.45–1.94], declined high LDL-C (&gt;160 to &lt;100 mg/dL; aHR = 1.23, 95% CI = 1.11–1.38), and borderline LDL-C (approximately 140 mg/dL over time; aHR = 1.16, 95% CI = 1.07–1.26) groups than in the optimal LDL-C group (&lt;100 mg/dL over time). There was no such association in patients with an eGFR &lt;15 mL/min/1.73 m2. Persistent diabetes was associated with a 1.15–2.47-fold increase in CVD in patients with high LDL-C (&gt;120 mg/dL).ConclusionThe LDL-C trajectory pattern was associated with the phenotype of CVD risk. The degree of risk varied according to eGFR and diabetes status. A stable low LDL-C over time was potentially beneficial for prevention of CVD. Intensive lipid management and periodic assessment of LDL-C is essential to reduce the risk of CVD in patients with CKD and diabetes

Triggering Apoptotic Death of Human Malignant Melanoma A375.S2 Cells by Bufalin: Involvement of Caspase Cascade-Dependent and Independent Mitochondrial Signaling Pathways

Bufalin was obtained from the skin and parotid venom glands of toad and has been shown to induce cytotoxic effects in various types of cancer cell lines, but there is no report to show that whether bufalin affects human skin cancer cells. The aim of this investigation was to study the effects of bufalin on human malignant melanoma A375.S2 cells and to elucidate possible mechanisms involved in induction of apoptosis. A375.S2 cells were treated with different concentrations of bufalin for a specific time period and investigated for effects on apoptotic analyses. Our results indicated that cells after exposure to bufalin significantly decreased cell viability, and induced cell morphological changes and chromatin condensation in a concentration-dependent manner. Flow cytometric assays indicated that bufalin promoted ROS productions, loss of mitochondrial membrane potential (ΔΨm), intracellular Ca2+ release, and nitric oxide (NO) formations in A375.S2 cells. Additionally, the apoptotic induction of bufalin on A375.S2 cells resulted from mitochondrial dysfunction-related responses (disruption of the ΔΨm and releases of cytochrome c, AIF, and Endo G), and activations of caspase-3, caspase-8 and caspase-9 expressions. Based on those observations, we suggest that bufalin-triggered apoptosis in A375.S2 cells is correlated with extrinsic- and mitochondria-mediated multiple signal pathways