Lipopolysaccharides in diazotrophic bacteria

TNFAIP3 interacting protein 2 relieves lipopolysaccharide (LPS)-induced inflammatory injury in endometritis by inhibiting NF-kappaB activation

BACKGROUND

Endometritis seriously affects the health of women, and it is important to identify new targets for its treatment.

OBJECTIVE

This study aimed to explore the role of TNFAIP3 interacting protein 2 (TNIP2) in endometritis through human endometrial epithelial cells (hEECs) stimulated by lipopolysaccharide (LPS).

METHODS

hEECs were induced with LPS to build a cellular model of endometritis. Cell growth and apoptosis were detected by cell counting kit-8 and flow cytometry. The TNIP2 mRNA and protein levels were measured using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis, respectively. The caspase3 activity was calculated using a Caspase3 activity kit. Interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) levels were determined by enzyme-linked-immunosorbent-assay. The reactive oxygen species (ROS), lactate dehydrogenase (LDH), catalase (CAT), and superoxide dismutase (SOD) levels were determined using the corresponding kits. Nuclear factor-kappaB (NF-κB) pathway was determined by western blot assay.

RESULTS

TNIP2 was downregulated in the LPS-induced endometritis cell model. Cell viability was reduced, apoptosis was enhanced, and IL-6, IL-1β, and TNF-α levels increased in LPS-induced hEECs. Additionally, LDH activity and ROS concentration were upregulated, whereas CAT and SOD activities were downregulated in LPS-induced hEECs. These results were reversed by TNIP2 overexpression. Moreover, the results hinted that NF-κB was involved in the effects of TNIP2 on the LPS-induced endometritis cell model.

CONCLUSION

TNIP2 alleviated endometritis by inhibiting the NF-κB pathway, suggesting a potential therapeutic target for endometritis.

DFT evaluation of structural, electronic and variation properties for complex carbohydrates with biological interest

The synthetic bicyclic bis(hemiacetals) compounds 1,5-pyranose-9,7-pyranoses, with a structural analogy to the bicyclic monosaccharide Bradyrhizose, have been described here based on a theoretical approach, using DFT calculations with the B3LYP functional combined with the 6-311 + G(d,p) basis set. First, we have performed a geometrical and electronic properties description of (1 R,9S), (1S,9S) and (1S,9R)-1,5-pyranose-9,7-pyranoses. Results analysis indicated that, slight differences in the three-dimensional orientations of their atoms lead to an enormous difference in chemical reactivity. Consequently, (1S,9S) and (1S,9R) isomers are predicted to be the most resembling the natural bradyrhizose in structural features. To enhance the performance of these two isomers, a set of modifications through functional groups attached to the reactive sites were determined by local reactivity descriptors. Subsequently, in order to get more information on the obtained derivatives for both isomers, HOMO, LUMO, Egap and four electronic parameters were calculated and compared. The substituted systems show a good performance in chemical reactivity than the unmodified parent compounds.Communicated by Ramaswamy H. Sarma.

Hopanoids Confer Robustness to Physicochemical Variability in the Niche of the Plant Symbiont Bradyrhizobium diazoefficiens

Rhizobia are a group of bacteria that increase soil nitrogen content through symbiosis with legume plants. The soil and symbiotic host are potentially stressful environments, and the soil will likely become even more stressful as the climate changes. Many rhizobia within the Bradyrhizobium clade, like Bradyrhizobium diazoefficiens, possess the genetic capacity to synthesize hopanoids, steroid-like lipids similar in structure and function to cholesterol. Hopanoids are known to protect against stresses relevant to the niche of B. diazoefficiens. Paradoxically, mutants unable to synthesize the extended class of hopanoids participate in symbioses with success similar to that of the wild type, despite being delayed in root nodule initiation. Here, we show that in B. diazoefficiens, the growth defects of extended-hopanoid-deficient mutants can be at least partially compensated for by the physicochemical environment, specifically, by optimal osmotic and divalent cation concentrations. Through biophysical measurements of lipid packing and membrane permeability, we show that extended hopanoids confer robustness to environmental variability. These results help explain the discrepancy between previous in-culture and in planta results and indicate that hopanoids may provide a greater fitness advantage to rhizobia in the variable soil environment than the more controlled environments within root nodules. To improve the legume-rhizobium symbiosis through either bioengineering or strain selection, it will be important to consider the full life cycle of rhizobia, from soil to symbiosis. IMPORTANCE Rhizobia, such as B. diazoefficiens, play an important role in the nitrogen cycle by making nitrogen gas bioavailable through symbiosis with legume plants. As climate change threatens soil health, this symbiosis has received increased attention as a more sustainable source of soil nitrogen than the energy-intensive Haber-Bosch process. Efforts to use rhizobia as biofertilizers have been effective; however, long-term integration of rhizobia into the soil community has been less successful. This work represents a small step toward improving the legume-rhizobium symbiosis by identifying a cellular component-hopanoid lipids-that confers robustness to environmental stresses rhizobia are likely to encounter in soil microenvironments as sporadic desiccation and flooding events become more common.

Structure and genetics of the O-antigen of Enterobacter cloacae K7 containing di-N-acetylpseudaminic acid

The O-antigen (O-polysaccharide) is an essential component of lipopolysaccharide on the surface of Gram-negative bacteria and plays an important role in interaction with host organisms. In this study, we investigated the chemical structure and characterized the gene cluster of Enterobacter cloacae K7 O-antigen. As judged by sugar analyses along with NMR spectroscopy data, E. cloacae K7 antigen has a tetrasaccharide O-unit with the following structure: →8)-β-Psep5Ac7Ac-(2 → 2)-β-l-Rhap-(1 → 4)-α-l-Rhap-(1 → 3)-α-d-Galp-(1→ The O-antigen gene cluster of E. cloacae K7 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases.

An easy disinfection strategy for pipes connecting hemodialysis equipment

INTRODUCTION

A hemodialysis room has pipes connecting the console and central fluid equipment. While these pipes require disinfection, reports detailing disinfection strategies are unavailable. Therefore, we aimed to compare two easy disinfection strategies differing in sanitization frequency and sanitizer concentration.

METHODS

Reverse osmosis water (ROW) purifying equipment and six dialysis consoles were connected by 20 m of pipes. Only ROW flowed through these pipes, because the dialysate solution was constituted at each console. The pipes were sanitized by two strategies: (1) strong and monthly (hypochlorite concentration: 100 ppm) or (2) weak and weekly (5 ppm). Both strategies were easy because the sodium hypochlorite was simply added to the ROW tank. To estimate sanitization efficacy, endotoxin counts at the ROW tank outlet, the end of the pipe, and the pipe after the endotoxin-cutting filter in each console were measured monthly for six continuous months. These counts were compared between the two sanitization strategies.

RESULTS

The endotoxin counts at the ROW tank outlet and the end of the pipe were 0.004-0.017 and 0.012-0.081 EU/mL, respectively, in the strong and monthly strategy, and 0.001-0.003 and 0.001-0.005 EU/mL, respectively, in the weak and weekly strategy. The endotoxin counts at the pipe after the endotoxin-cutting filter were less than 0.001 EU/mL during the study period in both strategies.

CONCLUSION

A weekly disinfection strategy was more effective than a monthly one, despite the lower hypochlorite concentration. The present study suggests that frequency is the most important factor in the disinfection of pipes in a dialysis room.

Genome analysis of Chlamydia trachomatis for functional characterization of hypothetical proteins to discover novel drug targets

C. trachomatis is a Gram-negative bacterium that causes trachoma and sexually transmitted disease (STD) Chlamydia in humans. Chlamydial genital infections are the most frequent among all communicable diseases. The D/UW-3/Cx strain of C. trachomatis contains 935 genes and three pseudogenes. Out of these genes, 887 genes code for proteins while six for rRNA, 37 tRNA, and three genes translate into other RNAs. The proteome of C. trachomatis made of 887 proteins contains 269 Hypothetical proteins (HPs) that are subjected to functional characterization. This study suggests some known methods of functional characterization of such HPs. All of these methods are explicitly used to assign functions to the HPs with the accuracy of more than 90%. After extensive analysis of all the HPs, we have successfully assigned functions to 89 HPs with high precision. In the newly assigned HPs, there are enzymes, transporters, binding proteins, proteins involved in biosynthesis and regulatory processes and proteins with miscellaneous functions. The study suggests that the functionally annotated HPs may play a vital role in the growth and pathogenesis of this organism. Therefore, they can be considered potential drug targets.

Is using an open-reservoir cardiopulmonary bypass circuit after 6 days on standby safe?

OBJECTIVES

To investigate the sterility and biocompatibility of a stored open-reservoir cardiopulmonary bypass circuit maintained on standby.

METHODS

A total of four cardiopulmonary bypass circuits were assembled, primed and left to recirculate. One unit was placed in a positive-pressure operating room and the other three were placed in the intensive care unit. The primed solutions, which employed Ringer's acetate, hydroxyethylated starch and hydrate steroid, were sampled after 0, 24, 48, 72, 96, 120 and 144 h in all cardiopulmonary bypass circuits to measure the bacteria count, endotoxin count and chemical substances within the primed solution. Chemical substances were detected by assessing the following: the total organic carbon by the combustion oxidation infrared spectrometry, and molecular weight spread by gel permeation chromatography. The environments were left unattended and were uncovered during the storage period to mimic the clinical scenario.

RESULTS

There were no bacteria in any of the primed solutions, and only very minute concentrations of endotoxins were detected, both in the operating room and in the intensive care unit. The total organic carbon concentration was slightly more concentrated in the 144-h samples when compared with that in the 0-h samples. However, the molecular weight spread of the 0-h sample was identical to that in the 144-h sample.

DISCUSSION

With regard to the presence of bacteria and endotoxins, we noted that the hardshell reservoirs in the cardiopulmonary bypass circuit were effectively sealed and not invaded by bacteria. With regard to the presence of chemical substances, we noted that an increase in total organic carbon concentration was caused by bedewing, and that there was no release of chemical substances such as a polymer-coating agent, or other molecular materials in the primed solution.

CONCLUSIONS

There was no contamination or release of chemical substances in 6-day old cardiopulmonary bypass circuits maintained on standby, confirming that they are safe to use in terms of sterility and biocompatibility.