Production of light olefins and monocyclic aromatic hydrocarbons from the pyrolysis of waste plastic straws over high-silica zeolite-based catalysts.

Owing to the ever-increasing generation of plastic waste, the need to develop environmentally friendly disposal methods has increased. This study explored the potential of waste plastic straw to generate valuable light olefins and monocyclic aromatic hydrocarbons (MAHs) via catalytic pyrolysis using high-silica zeolite-based catalysts. HZSM-5 (SiO2/Al2O3:200) exhibited superior performance, yielding more light olefins (49.8 wt%) and a higher MAH content than Hbeta (300). This was attributed to the increased acidity and proper shape selectivity. HZSM-5 displayed better coking resistance (0.7 wt%) than Hbeta (4.4 wt%) by impeding secondary reactions, limiting coke precursor formation. The use of HZSM-5 (80) resulted in higher MAHs and lower light olefins than HZSM-5 (200) because of its higher acidity. Incorporation of Co into HZSM-5 (200) marginally lowered light olefin yield (to 44.0 wt%) while notably enhancing MAH production and boosting propene selectivity within the olefin composition. These observations are attributed to the well-balanced coexistence of Lewis and Brønsted acid sites, which stimulated the carbonium ion mechanism and induced H-transfer, cyclization, Diels-alder, and dehydrogenation reactions. The catalytic pyrolysis of plastic straw over high-silica and metal-loaded HZSM-5 catalysts has been suggested as an efficient and sustainable method for transforming plastic waste materials into valuable light olefins and MAHs.

Recent advances in liquid fuel production from plastic waste via pyrolysis: Emphasis on polyolefins and polystyrene.

The management of plastic waste (PW) has become an indispensable worldwide issue because of the enhanced accumulation and environmental impacts of these waste materials. Thermo-catalytic pyrolysis has been proposed as an emerging technology for the valorization of PW into value-added liquid fuels. This review provides a comprehensive investigation of the latest advances in thermo-catalytic pyrolysis of PW for liquid fuel generation, by emphasizing polyethylene, polypropylene, and polystyrene. To this end, the current strategies of PW management are summarized. The various parameters affecting the thermal pyrolysis of PW (e.g., temperature, residence time, heating rate, pyrolysis medium, and plastic type) are discussed, highlighting their significant influence on feed reactivity, product yield, and carbon number distribution of the pyrolysis process. Optimizing these parameters in the pyrolysis process can ensure highly efficient energy recovery from PW. In comparison with non-catalytic PW pyrolysis, catalytic pyrolysis of PW is considered by discussing mechanisms, reaction pathways, and the performance of various catalysts. It is established that the introduction of either acid or base catalysts shifts PW pyrolysis from the conventional free radical mechanism towards the carbonium ion mechanism, altering its kinetics and pathways. This review also provides an overview of PW pyrolysis practicality for scaling up by describing techno-economic challenges and opportunities, environmental considerations, and presenting future outlooks in this field. Overall, via investigation of the recent research findings, this paper offers valuable insights into the potential of thermo-catalytic pyrolysis as an emerging strategy for PW management and the production of liquid fuels, while also highlighting avenues for further exploration and development.

Particulate matter10-induced airway inflammation and fibrosis can be regulated by chitinase-1 suppression.

BACKGROUND: Particulate matter10 (PM10) can induce airway inflammation and fibrosis. Recently, chitinase-1 has been shown to play key roles in inflammation and fibrosis. We aimed to investigate the effects of chitinase-1 inhibitor in PM10-treated murine mice models. METHODS: In female BALB/c mice, PM10 was intranasally administered six times over 3 weeks, and ovalbumin (OVA) was intraperitoneally injected and then intranasally administered. Chitinase-1 inhibitor (CPX) 6 times over 3 weeks or dexamethasone 3 times in the last week were intraperitoneally administered. Two days after the last challenges, mice were euthanized. Messenger RNA sequencing using lung homogenates was conducted to evaluate signaling pathways. RESULTS: PM10 and/or OVA-induced airway inflammation and fibrosis murine models were established. CPX and dexamethasone ameliorated PM10 or PM10/OVA-induced airway hyper-responsiveness, airway inflammation, and fibrosis. CPX and dexamethasone also reduced levels of various inflammatory markers in lung homogenates. PM10 and OVA also induced changes in mRNA expression across an extreme range of genes. CPX and dexamethasone decreased levels of mRNA expression especially associated with inflammation and immune regulation. They also significantly regulated asthma and asthma-related pathways, including the JACK-STAT signaling pathway. CONCLUSIONS: Chitinase-1 suppression by CPX can regulate PM10- and OVA-induced and aggravated airway inflammation and fibrosis via an asthma-related signaling pathway.

Life expectancy and healthy life expectancy of Korean registered disabled by disability type in 2014-2018: Korea National Rehabilitation Center database.

BACKGROUND: Conducting a distinct comparison between the life expectancy (LE) and healthy life expectancy (HALE) of people with disabilities (PWDs) and the general population is necessary due to the various environmental and health conditions they encounter. Therefore, this study aimed to develop the life table for PWDs and calculate those of LE and HALE based on sex, severity, and disability types among the registered Korean PWDs. METHODS: We used aggregated data of registered PWDs from the Korea National Rehabilitation Center database between 2014 and 2018. Overall, 345,595 deaths were included among 12,627,428 registered PWDs. First, we calculated the LE for total PWDs and non-disabled people using a standard life table, extending the old age mortality among nine models. Subsequently, we calculated the LE for each type of disability using the relationship between the mortality of total PWDs and those of each type of disability. Finally, HALE was calculated using the Sullivan method for three types as follows: disability-free and perceived health (PH) using the National Survey, and hospitalized for ≥ 7 days using the Korea National Health Insurance System (NHIS) database. RESULTS: The calculated LE/HALE-NHIS (years) at registration in males and females were 81.32/73.32 and 87.38/75.58, 68.54/58.98 and 71.43/59.24, 73.87/65.43 and 78.25/67.51, and 61.53/50.48 and 62.41/49.72 years among non-disabled, total PWDs, mild disabled, and severe disabled, respectively. LE/HALE-NHIS was lowest and highest in respiratory dysfunction and hearing disabilities, respectively. CONCLUSIONS: Males with disabilities had shorter LE and HALE at registration than females, except for those with severe disabilities, and there were variabilities in the LE based on the disability types.

Biochar application strategies for polycyclic aromatic hydrocarbons removal from soils.

Polycyclic aromatic hydrocarbons (PAHs) are known as a hazardous group of pollutants in the soil which causes many challenges to the environment. In this study, the potential of biochar (BC), as a carbonaceous material, is evaluated for the immobilization of PAHs in soils. For this purpose, various bonding mechanisms of BC and PAHs, and the strength of bonds are firstly described. Also, the effect of impressive criteria including BC physicochemical properties (such as surface area, porosity, particle size, polarity, aromaticity, functional group, etc., which are mostly the function of pyrolysis temperature), number of rings in PAHs, incubation time, and soil properties, on the extent and rate of PAHs immobilization by BC are explained. Then, the utilization of BC in collaboration with biological tools which simplifies further dissipation of PAHs in the soil is described considering detailed interactions among BC, microbes, and plants in the soil matrix. The co-effect of BC and biological remediation has been authenticated by previous studies. Moreover, recent technologies and challenges related to the application of BC in soil remediation are explained. The implementation of a combined BC-biological remediation method would provide excellent prospects for PAHs-contaminated soils.

The ecology of medical care in Korea: the association of a regular doctor and medical care utilization.

BACKGROUNDS: There is no registered regular doctor system in Korea, but people voluntarily select regular doctors for medical services. This study aims to study the ecology of medical care in Korea according to the presence and type of a regular doctor. METHODS: This study was conducted using Korean Health Panel survey in 2018. The proportion of people who had health problems and received medical care in various settings was analyzed per 1,000 people according to the following groups: without a regular doctor, having a clinic physician as a regular doctor, and having a hospital physician as a regular doctor. The adjusted odds ratio for usage of medical services was calculated. RESULTS: Health problems and medical care use increased in the groups in this order: group without a regular doctor, group with a clinic physician as a regular doctor, the group with a hospital physician a regular doctor. Having a hospital physician as a regular doctor was associated with higher odds of inpatient care and emergency room visits, and having a clinic physician as a regular doctor was not associated with odds of inpatient care and emergency room visits when adjusting demographic and health-related variables. CONCLUSION: Depending on whether having a regular doctor and a regular doctor's type, different ecology of medical care was observed. The position and role of a regular doctor in the context of the Korea health care system should be considered from the perspective of primary care.

Isolation and Characterization of a Yellow Xanthophyll Pigment-Producing Marine Bacterium, Erythrobacter sp. SDW2 Strain, in Coastal Seawater.

Xanthophylls, a yellow pigment belonging to the carotenoid family, have attracted much attention for industrial applications due to their versatile nature. We report the isolation of a homo xanthophyll pigment-producing marine bacterium, identified as the Erythrobacter sp. SDW2 strain, from coastal seawater. The isolated Erythrobacter sp. SDW2 strain can produce 263 ± 12.9 mg/L (89.7 ± 5.4 mg/g dry cell weight) of yellow xanthophyll pigment from 5 g/L of glucose. Moreover, the xanthophyll pigment produced by the SDW2 strain exhibits remarkable antioxidative activities, confirmed by the DPPH (73.4 ± 1.4%) and ABTS (84.9 ± 0.7%) assays. These results suggest that the yellow xanthophyll pigment-producing Erythrobacter sp. SDW2 strain could be a promising industrial microorganism for producing marine-derived bioactive compounds with potential for foods, cosmetics, and pharmaceuticals.

Rapid Diagnosis of Coronavirus by RNA-Directed RNA Transcription Using an Engineered RNA-based Platform.

A coronavirus disease (COVID-19) outbreak associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading widely through person-to-person transmission. Various detection approaches have been developed involving quantitative polymerase chain reaction (qPCR) methods, CRISPR-based systems, and direct targeting of specific coronavirus proteins. However, there have only been a few reports on the detection of RNA-dependent RNA polymerase (RdRP), the primer-independent RNA-replicable protein produced by the RNA genes of coronavirus. Here, we introduce a novel diagnostic methodology for COVID-19 using the RNA-directed and de novo RNA replicable function of RdRP. We devised an RNA platform for RdRP-induced transcription (RPRIT) that includes an RNA template that can be directly transcribed by RdRP. By utilizing RPRIT, the presence of RdRP can be readily confirmed within 30 min using isothermal incubation without PCR. This RdRP detection method can provide a new route for rapid diagnosis of RNA virus-infected patients.

Effect of asthma and asthma medication on the prognosis of patients with COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has spread worldwide rapidly. However, the effects of asthma, asthma medication and asthma severity on the clinical outcomes of COVID-19 have not yet been established. METHODS: The study included 7590 de-identified patients, who were confirmed to have COVID-19 using the severe acute respiratory syndrome coronavirus 2 RNA-PCR tests conducted up to May 15, 2020; we used the linked-medical claims data provided by the Health Insurance Review and Assessment Service. Asthma and asthma severity (steps suggested by the Global Initiative for Asthma) were defined using the diagnostic code and history of asthma medication usage. RESULTS: Among 7590 COVID-19 patients, 218 (2.9%) had underlying asthma. The total medical cost associated with COVID-19 patients with underlying asthma was significantly higher than that of other patients. Mortality rate for COVID-19 patients with underlying asthma (7.8%) was significantly higher than that of other patients (2.8%; p<0.001). However, asthma was not an independent risk factor for the clinical outcomes of COVID-19 after adjustment, nor did asthma medication use and asthma severity affect the clinical outcomes of COVID-19. However, use of oral short-acting ß2-agonists was an independent factor to increase the total medical cost burden. Patients with step 5 asthma showed significant prolonged duration of admission compared to those with step 1 asthma in both univariate and multivariate analysis. CONCLUSIONS: Asthma led to poor outcomes of COVID-19; however, underlying asthma, use of asthma medication and asthma severity were not independent factors for poor clinical outcomes of COVID-19, generally.

Bioremediation strategies with biochar for polychlorinated biphenyls (PCBs)-contaminated soils: A review.

Polychlorinated biphenyls (PCBs) are hazardous organic contaminants threatening human health and environmental safety due to their toxicity and carcinogenicity. Biochar (BC) is an eco-friendly carbonaceous material that can extensively be utilized for the remediation of PCBs-contaminated soils. In the last decade, many studies reported that BC is beneficial for soil quality enhancement and agricultural productivity based on its physicochemical characteristics. In this review, the potential of BC application in PCBs-contaminated soils is elaborated as biological strategies (e.g., bioremediation and phytoremediation) and specific mechanisms are also comprehensively demonstrated. Further, the synergy effects of BC application on PCBs-contaminated soils are discussed, in view of eco-friendly, beneficial, and productive aspects.

Team-based primary care program for disabled people and changes in rate of unmet health care needs.

BACKGROUND: Few studies have been conducted on the application of specific and practical methods, such as interventions, for reducing the unmet health care needs (UHCN) of disabled people. OBJECTIVES: The study aims to evaluate the impact of the team-based primary care program (TPCP) for disabled people on UHCN. METHOD: In 2017, we surveyed 696 disabled people who were enrolled in the TPCP at one of the 11 institutions belonging to the Korea Health Welfare Social Cooperative Federation from 2015 to 2017 to assess their unmet needs before and after enrolment. We conducted a logistic regression analysis before and after the program to evaluate the relationship between participation period and unmet needs after adjusting for physician type, gender, age, drinking, monthly income, disability type, personal assistance services and living alone. RESULT: After using the service, the proportion of disabled people with unmet needs decreased from 42.9% to 20.4% for a medical doctor and 43.6% to 18.6% for a Korean medical (KM) doctor. After adjusting for related factors and stratifying with type of physician, the proportion of disabled people with unmet needs decreased significantly in response to the participation period for the medical doctor-involved program (P-trend < 0.001); this was not observed in the KM counterpart (P-trend = 0.6). CONCLUSION: The TPCP for disabled people provides disease prevention, health care and health promotion activities and is crucial for solving the unmet needs.

6,8-Diprenylorobol induces apoptosis in human colon cancer cells via activation of intracellular reactive oxygen species and p53.

6,8-Diprenylorobol is a natural compound mainly found in Glycyrrhiza uralensis fisch and Maclura tricuspidata, which has been used traditionally as food and medicine in Asia. So far, the antiproliferative effect of 6,8-diprenylorobol has not been studied yet in colon cancer. In this study, we aimed to evaluate the antiproliferative effects of 6,8-diprenylorobol in LoVo and HCT15, two kinds of human colon cancer cells. 6,8-Diprenylorobol inhibited the proliferation of LoVo and HCT15 cells in a dose- and time-dependent manner. A 40 µM of 6,8-diprenylorobol for 72 h reduced both of cell viability under 50%. After treatment of 6,8-diprenylorobol (40 and 60 µM) for 72 h, late apoptotic cell portion in LoVo and HCT15 cells were 24, 70% and 13, 90%, respectively, which was confirmed by checking DNA fragmentation in both cells. Mechanistically, 6,8-diprenylorobol activated p53 and its phosphorylated form (Ser15, Ser20, and Ser46) expression but suppressed Akt and mitogen-activated protein kinases (MAPKs) phosphorylation in LoVo and HCT15 cells. Interestingly, 6,8-diprenylorobol induced the generation of intracellular reactive oxygen species (ROS), which was attenuated with N-acetyl cysteine (NAC) treatment. Compared to the control, 60 µM of 6,8-diprenylorobol caused to increase ROS level to 210% in LoVo and HCT15, which was reduced into 161% and 124%, respectively with NAC. Furthermore, cell viability and apoptotic cell portion by 6,8-diprenylorobol was recovered by incubation with NAC. Taken together, these results indicate that 6,8-diprenylorobol has the potential antiproliferative effect against LoVo and HCT15 colon cancer cells through activation of p53 and generation of ROS.

Control of the Induced Handedness of Helical Nanofilaments Employing Cholesteric Liquid Crystal Fields.

In this paper, a simple and powerful method to control the induced handedness of helical nanofilaments (HNFs) is presented. The nanofilaments are formed by achiral bent-core liquid crystal molecules employing a cholesteric liquid crystal field obtained by doping a rod-like nematogen with a chiral dopant. Homochiral helical nanofilaments are formed in the nanophase-separated helical nanofilament/cholesteric phase from a mixture with a cholesteric phase. This cholesteric phase forms at a temperature higher than the temperature at which the helical nanofilament in a bent-core molecule appears. Under such conditions, the cholesteric liquid crystal field acts as a driving force in the nucleation of HNFs, realizing a perfectly homochiral domain consisting of identical helical nanofilament handedness.

Reduction of visceral fat could be related to the improvement of TBS in diabetes mellitus.

INTRODUCTION: Diabetes has been proposed as a risk factor for increased skeletal fragility. Visceral fat is known to yield adverse effects on bone metabolism in people with diabetes. We investigated the relationship between the change in visceral fat mass over time and TBS or BMD. MATERIALS AND METHODS: This retrospective study enrolled 690 (male: 367; female: 323) subjects with type 2 diabetes mellitus. Visceral fat mass, lumbar and femoral neck BMD, and lumbar spine TBS were measured via dual-energy X-ray absorptiometry (DXA), including the follow-up data within a 3-year period. RESULTS: TBS significantly increased as visceral fat mass decreased in both sexes (p < 0.001), whereas lumbar BMD and femoral neck BMD showed meaningful changes only in men. The multiple regression model with adjustment for age, weight, creatinine level, lipid profile, HbA1C, and status of osteoporosis medication use revealed that TBS and femoral neck BMD were correlated with visceral fat mass. However, regarding longitudinal changes, only the change in visceral fat mass had a significant relationship with TBS (males: ß = - 0.298, p < 0.001; females: ß = - 0.216, p < 0.001). CONCLUSIONS: The results of this study may suggest the beneficial effect of controlling visceral fat mass on bone health in type 2 diabetes patients. Besides, DXA-derived TBS could be a useful diagnostic tool for evaluating the bone changes according to metabolic changes in type 2 diabetes, which are not entirely achieved with BMD.

Case report: nosocomial fungemia caused by Candida diddensiae.

BACKGROUND: Candida diddensiae, a yeast found in olive oil, is considered non-pathogenic to humans. Here, we describe the first case of fungemia caused by C. diddensiae in a hospitalized patient with underlying diseases. CASE PRESENTATION: A 62-year-old woman was admitted because of multiple contusions due to repeated falls and generalized weakness. She presented with chronic leukopenia due to systemic lupus erythematosus, and multiple cranial nerve neuropathies due to a recurring chordoma. She was given a lipid emulsion containing total parenteral nutrition (TPN) starting on the day of admission. Broad-spectrum antibiotics had been administered during her last hospital stay and from day 8 of this hospitalization. However, no central venous catheter was used during this hospital stay. Blood cultures obtained on hospital days 17, 23, and 24 yielded the same yeast, which was identified as C. diddensiae via sequence analyses of the internal transcribed spacer region and D1/D2 regions of the 26S ribosomal DNA of the rRNA gene. In vitro susceptibility testing showed that the minimum inhibitory concentration of fluconazole for all isolates was 8 µg/mL. On day 23, TPN was discontinued and fluconazole therapy was started. Blood cultures obtained on day 26 were negative. The fluconazole therapy was replaced with micafungin on day 26 and the patient exhibited improvements. CONCLUSION: The use of lipid TPN may potentially contribute to the occurrence of nosocomial fungemia by C. diddensiae, an unusual Candida species.

Trabecular Bone Score Is a Useful Parameter for the Prediction of Vertebral Fractures in Patients With Polymyalgia Rheumatica.

INTRODUCTION: Polymyalgia rheumatica (PMR), a benign rheumatic disorder, requires long-term glucocorticoid therapy, which could be associated with osteoporosis. In the present study, we compared bone mineral density (BMD), trabecular bone score (TBS) and frequencies of vertebral fracture (VF) among patients with PMR or rheumatoid arthritis (RA) and controls. METHODS: Fifty-three postmenopausal women with PMR aged 50 yr or older were eligible for inclusion in this study. Subjects in RA (n = 106) and control (n = 106) groups were selected by propensity score matching with controlling age, body mass index and use of anti-osteoporotic agents. RESULTS: The frequency of VF in patients with PMR (30.2%) was significantly higher than those in patients with RA (13.2 %) and controls (13.2%, p = 0.017). The mean TBS of patients with PMR (1.317 ± 0.092) was significantly lower than those of patients with RA (1.336 ± 0.089) and the controls (1.373 ± 0.073, p < 0.001). In receiver operating characteristic analysis for VF in patients with PMR, the area under the curve (AUC) was 0.759 (95% confidence interval [CI] = 0.601-0.918, p < 0.001) for TBS and 0.618 (95% CI = 0.442-0.795, p < 0.001) for L-spine BMD. The AUCs were 0.760 (95% CI = 0.630-0.891, p ≤ 0.001) and 0.767 (95% CI 0.627-0.907, p < 0.001) for femur neck and total hip BMD, respectively. Multivariate analysis identified the factor associated with VF of patients with PMR as a lower TBS (Odds ratio: 0.000, 95% CI: 0.000, 0.754, p = 0.043). CONCLUSION: TBS could be a supplementary tool for discriminating osteoporotic fractures in postmenopausal patients with PMR.

Trabecular bone score may indicate chronic kidney disease-mineral and bone disorder (CKD-MBD) phenotypes in hemodialysis patients: a prospective observational study.

BACKGROUND: In the general population, the trabecular bone score (TBS) represents the bone microarchitecture and predicts fracture risk independent of bone mineral density (BMD). A few studies reported that TBS is significantly reduced in dialysis patients. Chronic kidney disease-mineral and bone disorder (CKD-MBD) are accompanied by increased fracture risk, cardiovascular morbidity, and mortality. We investigated whether TBS is associated with comorbidity related to CKD-MBD or frailty in hemodialysis patients. METHODS: In this prospective observational study, TBS was obtained using the TBS iNsight software program (Med-Imaps) with BMD dual energy x-ray absorptiometry (DXA) images (L1-L4) from prevalent hemodialysis patients. A Tilburg frailty indicator was used to evaluate frailty, and hand grip strength and bio-impedance (InBody) were measured. A patient-generated subjective global assessment (PG-SGA) was used for nutritional assessment. The history of cardiovascular events (CVE) and demographic, clinical, laboratory, and biomarker data were collated. We then followed up patients for the occurrence of CKD-MBD related complications. RESULTS: We enrolled 57 patients in total. The mean age was 56.8 ± 15.9 years (50.9% female). Prevalence of Diabetes mellitus (DM) was 40.4% and CVE was 36.8%. Mean TBS was 1.44 ± 0.10. TBS significantly reduced in the CVE group (1.38 ± 0.08 vs. 1.48 ± 0.10, p <  0.001). Multivariable regression analysis was conducted adjusting for age, sex, dialysis vintage, DM, CVE, albumin, intact parathyroid hormone, fibroblast growth factor 23, handgrip strength, and phosphate binder dose. Age (ß = - 0.030; p = 0.001) and CVE (ß = - 0.055; p = 0.024) were significant predictors of TBS. During the follow up period after TBS measurements (about 20 months), four deaths, seven incident fractures, and six new onset CVE were recorded. Lower TBS was associated with mortality (p = 0.049) or new onset fracture (p = 0.007, by log-rank test). CONCLUSION: Lower TBS was independently associated with increased age and CVE prevalence in hemodialysis patients. Mortality and fracture incidence were significantly higher in patients with lower TBS values. These findings suggest that TBS may indicate a phenotype of frailty and also a CKD-MBD phenotype reciprocal to CVE.

Extremophilic Microorganisms for the Treatment of Toxic Pollutants in the Environment.

As concerns about the substantial effect of various hazardous toxic pollutants on the environment and public health are increasing, the development of effective and sustainable treatment methods is urgently needed. In particular, the remediation of toxic components such as radioactive waste, toxic heavy metals, and other harmful substances under extreme conditions is quite difficult due to their restricted accessibility. Thus, novel treatment methods for the removal of toxic pollutants using extremophilic microorganisms that can thrive under extreme conditions have been investigated during the past several decades. In this review, recent trends in bioremediation using extremophilic microorganisms and related approaches to develop them are reviewed, with relevant examples and perspectives.

Microbial production of short-chain alkanes.

Increasing concerns about limited fossil fuels and global environmental problems have focused attention on the need to develop sustainable biofuels from renewable resources. Although microbial production of diesel has been reported, production of another much in demand transport fuel, petrol (gasoline), has not yet been demonstrated. Here we report the development of platform Escherichia coli strains that are capable of producing short-chain alkanes (SCAs; petrol), free fatty acids (FFAs), fatty esters and fatty alcohols through the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway. First, the ß-oxidation pathway was blocked by deleting the fadE gene to prevent the degradation of fatty acyl-CoAs generated in vivo. To increase the formation of short-chain fatty acids suitable for subsequent conversion to SCAs in vivo, the activity of 3-oxoacyl-ACP synthase (FabH), which is inhibited by unsaturated fatty acyl-ACPs, was enhanced to promote the initiation of fatty acid biosynthesis by deleting the fadR gene; deletion of the fadR gene prevents upregulation of the fabA and fabB genes responsible for unsaturated fatty acids biosynthesis. A modified thioesterase was used to convert short-chain fatty acyl-ACPs to the corresponding FFAs, which were then converted to SCAs by the sequential reactions of E. coli fatty acyl-CoA synthetase, Clostridium acetobutylicum fatty acyl-CoA reductase and Arabidopsis thaliana fatty aldehyde decarbonylase. The final engineered strain produced up to 580.8 mg l(-1) of SCAs consisting of nonane (327.8 mg l(-1)), dodecane (136.5 mg l(-1)), tridecane (64.8 mg l(-1)), 2-methyl-dodecane (42.8 mg l(-1)) and tetradecane (8.9 mg l(-1)), together with small amounts of other hydrocarbons. Furthermore, this platform strain could produce short-chain FFAs using a fadD-deleted strain, and short-chain fatty esters by introducing the Acinetobacter sp. ADP1 wax ester synthase (atfA) and the E. coli mutant alcohol dehydrogenase (adhE(mut)).

Protective effects of hepatocyte growth factor gene overexpression against hydrogen peroxide-induced apoptosis in mesenchymal stem cells.

Hepatocyte growth factor (HGF) has recently been reported to exhibit antioxidant and antiapoptotic effects. Therefore, we investigated the effect of overexpression of HGF gene in H2 O2 -treated mesenchymal stem cells (MSCs). HGF-overexpression increased the cell viability from 50% to 84%, decreased the population of apoptotic cells from 20% to 16%, and decreased the intracellular reactive oxygen species (ROS) levels from 127% to 100% in cells treated with H2 O2 . HGF suppression decreased the cell viability from 58% to 36%, increased the population of apoptotic cells from 23 to 81%, and increased the intracellular ROS levels from 181% to 240% in cells exposed to H2 O2 . HGF-overexpression also reduced the expression levels of proapoptotic proteins in MSCs treated with H2 O2 . Phosphorylation of extracellular signal-regulated kinases, c-Jun amino-terminal kinases, and p38, which was induced by H2 O2 , decreased in MSCs overexpressing the HGF gene. Taken together, our results suggest that HGF has a protective effect on H2 O2 -induced apoptosis in MSCs.