Optimization of isoprene production using a metabolically engineered Escherichia Coli

The volatile C5 hydrocarbon, isoprene is an important platform chemical, which has been used in the manufacture of synthetic rubber for tires and also has the potential for various other applications such as elastomers and adhesives. Moreover, isoprene is convertible to biofuel blend stocks such as C10 gasoline, C15 diesel, and jet fuels because of its higher energy content than other biofuels. Although isoprene is currently derived from petroleum, its sustainable supply has been suffered from price fluctuation of crude oil, high refining cost and energy consumption, and low recovery yield of pure isoprene. As an alternative, the biologically produced isoprene (bio-isoprene) has been developed rapidly for the last decade. Bio-isoprene is synthesized from dimethylallyl diphosphate (DMAPP), which is derived from mevalonate (MVA) pathway or the methylerythritol phosphate (MEP) pathway, by isoprene synthase. In this study, metabolic engineering for enhanced production of bio-isoprene was performed by deletion of relevant genes and optimization of culture condition. In comparison of isoprene production between E.coli DH5α and MG1655, lower isoprene production was observed in MG1655. The lower isoprene production in E. coli MG1655 was ascribed to the presence of recA gene which is absent in the DH5α strain. The deletion of recA gene in E.coli MG1655 allows higher isoprene production than E. coli DH5α. Moreover, the optimized expression of isoprene synthesis pathway with 0.03mM IPTG induction enhanced the isoprene production up to 2,850 mg/L. Overall, isoprene production through the optimization was improved by 28.5-fold compared to the initial production of MG1655 strain. Please click Additional Files below to see the full abstract

NUMERICAL ANALYSIS OF THERMAL STRATIFICATION IN THE UPPER PLENUM OF THE MONJU FAST REACTOR

A numerical analysis of thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (∼300 seconds). However, transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A nearly homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates. This discrepancy may be due to the shortcoming of the turbulence models available in the CFX-13 code for a natural convection flow with thermal stratification

3D Cell Printed Tissue Analogues: A New Platform for Theranostics

Stem cell theranostics has received much attention for noninvasively monitoring and tracing transplanted therapeutic stem cells through imaging agents and imaging modalities. Despite the excellent regenerative capability of stem cells, their efficacy has been limited due to low cellular retention, low survival rate, and low engraftment after implantation. Three-dimensional (3D) cell printing provides stem cells with the similar architecture and microenvironment of the native tissue and facilitates the generation of a 3D tissue-like construct that exhibits remarkable regenerative capacity and functionality as well as enhanced cell viability. Thus, 3D cell printing can overcome the current concerns of stem cell therapy by delivering the 3D construct to the damaged site. Despite the advantages of 3D cell printing, the in vivo and in vitro tracking and monitoring of the performance of 3D cell printed tissue in a noninvasive and real-time manner have not been thoroughly studied. In this review, we explore the recent progress in 3D cell technology and its applications. Finally, we investigate their potential limitations and suggest future perspectives on 3D cell printing and stem cell theranostics.116Nsciescopu

Topographical measurement of the attachments of the central band of the interosseous membrane on interosseous crests of the radius and ulna

Background To suggest a reasonable isometric point based on the anatomical consistency of interosseous membrane (IOM) attachment in association with topographic characteristics of the interosseous crests, the footprints of the central band (CB) of the IOM on the radial and ulnar interosseous crests (RIC and UIC) were measured. Methods We measured the distance from the CB footprints from each apex of both interosseous crests in 14 cadavers and the angles between the forearm axis of rotation (AOR) and the distal slopes of the RIC and UIC in 33 volunteers. Results The CB footprints lay on the downslope of both interosseous crests with its upper margin on average 3-mm proximal from the RIC's apex consistently in the radial length, showing normality (p>0.05), and on average 16-mm distal from the UIC's apex on the ulna without satisfying normality (p0.05), and there was no side-to-side difference in both forearms (p<0.05). Conclusions The CB attached to the downslope just distal to the RIC's apex constrains the radius to the UIC that coincides with the AOR of the forearm circumduction, maintaining itself both isometrically and isotonically

Oxygen Partial Pressure during Pulsed Laser Deposition: Deterministic Role on Thermodynamic Stability of Atomic Termination Sequence at SrRuO3/BaTiO3 Interface

With recent trends on miniaturizing oxide-based devices, the need for atomic-scale control of surface/interface structures by pulsed laser deposition (PLD) has increased. In particular, realizing uniform atomic termination at the surface/interface is highly desirable. However, a lack of understanding on the surface formation mechanism in PLD has limited a deliberate control of surface/interface atomic stacking sequences. Here, taking the prototypical SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) heterostructure as a model system, we investigated the formation of different interfacial termination sequences (BaO-RuO2 or TiO2-SrO) with oxygen partial pressure (PO2) during PLD. We found that a uniform SrO-TiO2 termination sequence at the SRO/BTO interface can be achieved by lowering the PO2 to 5 mTorr, regardless of the total background gas pressure (Ptotal), growth mode, or growth rate. Our results indicate that the thermodynamic stability of the BTO surface at the low-energy kinetics stage of PLD can play an important role in surface/interface termination formation. This work paves the way for realizing termination engineering in functional oxide heterostructures.Comment: 27 pages, 6 figures, Supporting Informatio

Extensive Emphysematous Pyelonephritis in a Nondiabetic Female Cat - Treatment with Unilateral Nephroureterectomy

Background: Emphysematous pyelonephritis (EPN) is an acute, severe necrotizing infection of the renal parenchyma and surrounding tissues that results in gas formation in the kidney, collecting system, or surroundings. EPN is a rare condition in veterinary medicine and occurs most frequently in dogs with diabetes mellitus. Although the prognosis of medical management in animals is poor, the standardized treatment protocol according to EPN severity is unclear. This report describes the first case of a nondiabetic female cat with extensive EPN and good prognosis following direct nephroureterectomy (NU). Case: A 10-year-old spayed female cat presented with the chief complaint of an acute loss of weight within 1 week, vomiting, and disorientation including stumbling, discoordination, circling, wobbling, head tilting, and difficulties in standing. At presentation, the patient had a body condition score of 1/9 and weighed 2.6 kg. Blood examination revealed leukocytosis, anemia, and hypoproteinemia. Abdominal radiography revealed severely decreased serosal details. A massive gas silhouette observed in the peritoneal and retroperitoneal cavities, was diagnosed as abdominal free gas. Abdominal ultrasound showed an accumulation of moderately anechoic fluid mixed with gas and cyst-like capsules around the left kidney. Left partial ureteral obstruction and dilation were also observed. Computed tomography (CT) was performed without sedatives or anesthetic drugs. The findings showed severe inflammatory changes in the peritoneum and a loss of the normal inner structure in the left kidney. A pyelogram of the left kidney was not observed after injection of the contrast material. Diffuse fat stranding and free gas observed in the mesentery of the entire abdominal cavity and around the left kidney were considered septic peritonitis. Urinalysis revealed proteinuria and hematuria. Numerous neutrophils with rod-type bacteria were observed in the ascites. Following diagnostic examinations, the patient was diagnosed with extensive left EPN, including inflammatory ascites and abdominal free gas. Therefore, emergency NU of the nonfunctional left kidney and ruptured ureter and thorough abdominal lavage were conducted. Diffuse inflammation and a nephrolith were observed in the section of the harvested kidney. The nephrolith was composed of 100% calcium oxalate monohydrate. The real-time polymerase chain reaction (RT-PCR) test for feline infectious peritonitis (FIP) was negative. Escherichia coli was detected in the ascites, and antibiotic therapy was administered following the antibiotic sensitivity test. The histological findings from the left kidney and ureter included marked chronic inflammation and fibrosis. The patient was discharged 4 days after surgery. During the 8-month follow-up period, the patient’s condition improved. Discussion: This was a unique case of EPN in a nondiabetic cat and the first reported case of EPN with a ruptured ureter, including abdominal free gas, inflammatory ascites, and peritonitis. This patient had a bacterial urinary tract infection with E. coli, which is the most frequently isolated pathogen in humans. This gas-forming bacteria produced a massive amount of gas and inflammation that were considered to have ruptured the urinary tract, so that the gas was released into the abdomen. This case corresponded to class 3B, with two risk factors according to the human EPN classification system. Direct NU and abdominal lavage were performed as emergency surgeries. The patient stabilized gradually and showed a good prognosis. Immediate surgical intervention is recommended in animal patients showing the extensive EPN stage. Keywords: kidney, nephroureterectomy, emphysematous pyelonephritis, peritonitis, cat, E. coli.