SARS-CoV-2 non-structural protein 6 triggers NLRP3-dependent pyroptosis by targeting ATP6AP1

A recent mutation analysis suggested that Non-Structural Protein 6 (NSP6) of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a key determinant of the viral pathogenicity. Here, by transcriptome analysis, we demonstrated that the inflammasome-related NOD-like receptor signaling was activated in SARS-CoV-2-infected lung epithelial cells and Coronavirus Disease 2019 (COVID-19) patients’ lung tissues. The induction of inflammasomes/pyroptosis in patients with severe COVID-19 was confirmed by serological markers. Overexpression of NSP6 triggered NLRP3/ASC-dependent caspase-1 activation, interleukin-1β/18 maturation, and pyroptosis of lung epithelial cells. Upstream, NSP6 impaired lysosome acidification to inhibit autophagic flux, whose restoration by 1α,25-dihydroxyvitamin D3, metformin or polydatin abrogated NSP6-induced pyroptosis. NSP6 directly interacted with ATP6AP1, a vacuolar ATPase proton pump component, and inhibited its cleavage-mediated activation. L37F NSP6 variant, which was associated with asymptomatic COVID-19, exhibited reduced binding to ATP6AP1 and weakened ability to impair lysosome acidification to induce pyroptosis. Consistently, infection of cultured lung epithelial cells with live SARS-CoV-2 resulted in autophagic flux stagnation, inflammasome activation, and pyroptosis. Overall, this work supports that NSP6 of SARS-CoV-2 could induce inflammatory cell death in lung epithelial cells, through which pharmacological rectification of autophagic flux might be therapeutically exploited.

ANALYSIS OF FUEL QUALITY EFFECT ON THE LIFE TIME FROM HIGH-PRESSURE PUMP OF ENGINE MTU 12 V 4000 M 71

Fuel is one of the important components in the combustion process. A good fuel is a clean fuel where the fuel is colorless, watery, has a high flash point, it can ignite spontaneously at a temperature of 350ºC, and has a specific gravity of about 0.82-0.86. On the other hand, KRI Kelabang-826 is an Indonesian republic warship that functions as a patrol boat. This causes the ship to have a medium duty engine, the MTU 12 V 4000 M 71 engine. This engine itself is a sophisticated engine because it uses common rail technology with a High-Pressure Pump as the supplying pump. This pump is very susceptible to damage, this is proven by not achieving the life time of the High-Pressure Pump which is 7500 Running Hours or once a W5- level maintenance. This is caused by poor quality of fuel, where the fuel used contains water and impurities. Therefore, the preventive ways are needed in order to achieve the life time of this High-Pressure Pump component. Keywords: Fuel Quality, MTU 12 V 4000 M 71, High-Pressure Pump, and Condor Class.

The 2019 Garrod Lecture: MDR efflux in Gram-negative bacteria—how understanding resistance led to a new tool for drug discovery

The AcrAB-TolC MDR efflux system confers intrinsic MDR and overproduction confers clinically relevant resistance to some antibiotics active against Gram-negative bacteria. The system is made up of three components, namely AcrA, AcrB and TolC, otherwise known as the AcrAB-TolC tripartite system. Inactivation or deletion of a gene encoding one of the constituent proteins, or substitution of a single amino acid in the efflux pump component AcrB that results in loss of efflux function, confers increased antibiotic susceptibility. Clinically relevant resistance can be mediated by a mutation in acrB that changes the way AcrB substrates are transported. However, it is more common that resistant clinical and veterinary isolates overproduce the AcrAB-TolC MDR efflux system. This is due to mutations in genes such as marR and ramR that encode repressors of transcription factors (MarA and RamA, respectively) that when produced activate expression of the acrAB and tolC genes thereby increasing efflux. The Lon protease degrades MarA and RamA to return the level of efflux to that of the WT. Furthermore, the levels of AcrAB-TolC are regulated by CsrA. Studies with fluorescent reporters that report levels of acrAB and regulatory factors allowed the development of a new tool for discovering efflux inhibitors. Screens of the Prestwick Chemical Library and a large library from a collaborating pharmaceutical company have generated a number of candidate compounds for further research.

Study on Corrosion Mechanism of Stellite Hard Alloy Layer of a Main Pump Component

Stellite 12 alloy was cladded on the surface of Thrust runner of a main pump using HIP technology. After product testing, lots of corrosions were found on the hard layer. SEM and EDS analysis technologies were used in order to find out the causes and mechanism inducing these corrosions. SEM results indicated that two kinds of corrosions locating on the hard layer. One type is central corrosion pit, another type is Selective Phase Corrosion (SPC).EDS showed that the central and adjacent corrosive areas were rich in carbon, low in cobalt, chromium and tungsten elements for the first type of corrosion. As for the second type of corrosion, EDS indicated that the corrosive zones were typically high in tungsten, chromium and carbon, and low in cobalt. Meanwhile, the presence of sulfur and chlorine elements may aggravate the initiation and continuation of corrosion.

ANALYSIS OF DEFECTS AND FAILU RES OF HYDRAULIC GEAR PUMPS WITH THE USE OF SELECTED QUALITATIVE METHODS

The paper presents an analysis of the defects and failures of a gear pump using the FMEA matrix analysis and error diagram. For each pump component, functions that are performed and potential defects were identified. Failures and defects that are typical for gear wheels were found as the main problem that influences pump malfunction. Therefore, using the error diagram, the main categories of causes were determined. In the next step, the identified causes and subcauses were assigned to defects with the highest possibility of occurrence, which allowed us to specify preventive and corrective actions.