Enhanced conversion of sterols to steroid synthons by augmenting the peptidoglycan synthesis gene pbpB in Mycobacterium neoaurum

Some species of mycobacteria have been modified to transform sterols to valuable steroid synthons. The unique cell wall of mycobacteria has been recognized as an important organelle to absorb sterols. Some cell wall inhibitors (e.g., vancomycin and glycine) have been validated to enhance sterol conversion by interfering with transpeptidation in peptidoglycan biosynthesis. Therefore, two transpeptidase genes, pbpA and pbpB, were selected to rationally modify the cell wall to simulate the enhancement effect of vancomycin and glycine on sterol conversion in a 22‐hydroxy‐23,24‐bisnorchol‐4‐ene‐3‐one (4‐HBC) producing strain (WIII). Unexpectedly, the pbpA or pbpB gene augmentation was conducive to the utilization of sterols. The pbpB augmentation strain WIII‐pbpB was further investigated for its better performance. Compared to WIII, the morphology of WIII‐pbpB was markedly changed from oval to spindle, indicating alterations of the cell wall. Biochemical analysis indicated that the altered cell wall properties of WIII‐pbpB might contribute to the positive effect on sterol utilization. The productivity of 4‐HBC was enhanced by 28% in the WIII‐pbpB strain compared to that of WIII. These results demonstrated that the modification of peptidoglycan synthesis can improve the conversion of sterols to steroid synthons in mycobacteria.     

Referencing the trochlear groove based on three-dimensional computed tomography imaging improves the reliability of the measurement of the tibial tuberosity–trochlear groove distance in patients with higher grades of trochlea dysplasia

BackgroundTo determine whether 3D-CT imaging technique is valid and reproducible compared to conventional CT measurement technique (CCT) for the detection of a femoropatellar instability.MethodsPatients who had undergone surgery for femoropatellar instability (patellar instability group) between 2010 and 2016 (n = 37 knees of 35 patients) were retrospectively enrolled. For the matched control group, patients who had acute anterior cruciate ligament injury (< 4 weeks previously; n = 30) were recruited. Preoperative CT data had been obtained in all patients. Inter-rater reliability was calculated for both measurement protocols, and inter-method reliability was calculated between the two imaging modalities. The results are reported using intraclass correlation coefficients (ICCs) and Bland–Altman 95% limits of agreement.ResultsAll patients in the patellar instability group had femoral trochlear dysplasia (Dejour types A: four, B: 19, C: seven, and D: six), but no dysplasia was noted in the control group. In the patellar instability group, the CCT technique showed a poor inter-rater agreement (ICC = 0.74), and the 3D-CT technique still showed excellent inter-rater agreement (ICCs = 0.91). In the sub-analysis of the patellar instability group according to the trochlear dysplasia grade, ICCs were markedly decreased with severe trochlear dysplasia when using CCT technique; however, the 3D-CT technique could provide excellent reliability even with severe trochlear dysplasia.ConclusionThe 3D-CT imaging technique for the measurement of the TT–TG distance can be suggested as a better measurement technique for patellar instability patients with bone abnormality.     

Preparation of Light‐Responsive Aliphatic Polycarbonate via Versatile Polycondensation for Controlled Degradation

Starting from (2,2,5‐trimethyl‐1,3‐dioxan‐5‐yl)methanamine with light‐responsive 4,5‐dimethoxy‐2‐nitrobenzyl protecting groups, a variety of light‐responsive copolycarbonates (LrPCs) are synthesized by a general two‐step polycondensation using lithium acetylacetonate (LiAcac) as catalyst. UV/Vis, ¹H nuclear magnetic resonance (NMR), and size exclusion chromatography (SEC) confirm the rapid decomposition of these polymers in response to irradiation with UV light. Stable and monodisperse nanoparticles with hydrodynamic diameters of 100 nm, formulated from 25% LrPC and 75% poly(lactic‐co‐glycolic acid) (PLGA), undergo rapid disruption upon triggering with UV light, while standard PLGA nanoparticles remain stable. Moreover, differing from the ring‐opening polymerization (ROP) of trimethylene carbonate‐based monomers, direct polycondensation of 1,3‐propanediol‐based monomers with pendent functional groups and other diols will enable the introduction of various properties into the polycarbonate backbone, and expand the family of biodegradable synthetic polymers for potential biomedical applications.     

TNF-α/calreticulin dual signaling induced NLRP3 inflammasome activation associated with HuR nucleocytoplasmic shuttling in rheumatoid arthritis

Inflammation Research - The present study was undertaken to validate whether TNF-α and calreticulin (CRT) serve as dual signaling to activate nucleotide-binding oligomerization domain-,...     

Graphene oxide regulates cox2 in human embryonic kidney 293T cells via epigenetic mechanisms: dynamic chromosomal interactions

To extend the applications of engineered nanomaterials, such as graphene oxide (GO), it is necessary to minimize cytotoxicity. However, the mechanisms underlying this cytotoxicity are unclear. Dynamic chromosomal interactions have been used to illustrate the molecular bases of gene expression, which offers a more sensitive and cutting-edge technology to elucidate complex biological processes associated with epigenetic regulations. In this study, the role of GO-triggered chromatin interactions in the activation of cox2, a hallmark of inflammation, was investigated in normal human cells. Using chromosome conformation capture technology, we showed that GO triggers physical interactions between the downstream enhancer and the cox2 promoter in human embryonic kidney 293T (293T) via p65 and p300 complex-mediated dynamic chromatin looping, which was required for high cox2 expression. Moreover, tumor necrosis factor-α (TNF-α), located upstream of the p65 signaling pathway, contributed to the regulation of cox2 activation through dynamic chromatin architecture. Compared with pristine GO and aminated GO (GO-NH₂), poly (acrylic acid)-functionalized GO (GO-PAA) induced a weaker inflammatory response and a weaker effect on chromatin architecture. Our results mechanistically link GO-mediated chromatin interactions with the regulation of cox2 and suggest that GO derivatives may minimize toxicity in practical applications.     

Peripheral blood leukocyte telomere length is associated with age but not renal function: A cross-sectional follow-up study

Objectives

We aimed to evaluate the relationship between baseline renal function and changes in telomere length in Han Chinese.

Methods

The telomere restriction fragment (TRF) length of leukocytes in the peripheral blood was measured in healthy volunteers recruited in 2014. The estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine (Scr) and serum cystatin C (CysC)-eGFRcys and eGFRScr-cys through the Cockcroft-Gault formula (eGFRC-G) or the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI / eGFRCKD-EPI) equation. The correlation between telomere length changes over time and renal function was analyzed.

Results

Leukocyte TRF lengths were negatively correlated to age (r = -0.393, p < 0.001) and serum CysC (r = -0.180, p < 0.01), while positively associated with eGFRCKD-EPI, eGFRC-G, eGFRcys, and eGFRScr-cys (r = 0.182, 0.122, 0.290, and 0.254 respectively, p < 0.01). The 3-year change of telomere length was 46 bp/years. When adjusted for age, the associations between telomere length changes and baseline, subsequent TRF lengths, and serum CysC were no longer present. No association was observed between TRF length changes and renal function.

Conclusion

The rate of telomere length changes was affected by age and baseline telomere length. The telomere length changes might be important markers for aging.

     

Gelatinase A (MMP-2) in developing tooth tissues and amelogenin hydrolysis

Matrix metalloproteinases (MMPs) are thought to play important roles during enamel and dentin biomineralization. Previously, membrane type-1 matrix metalloproteinase (MT1-MMP) was localized to the plasma membranes of ameloblasts and odontoblasts of the developing tooth. The best-characterized function of MT1-MMP is to initiate the activation of gelatinase A (MMP-2). Thus, we hypothesized that gelatinase A may also be expressed by developing tooth tissues. A full-length porcine gelatinase A mRNA was isolated by RT-PCR homology cloning of an enamel-organ-specific cDNA library. Northern blot and in situ hybridization analyses demonstrated gelatinase A expression in developing tooth tissues. Immunohistochemical analysis localized gelatinase A close to the plasma membrane of these tissues. Furthermore, recombinant gelatinase A was demonstrated to cleave recombinant amelogenin into several fragments of differing molecular masses. Thus, gelatinase A is expressed by developing tooth tissues along with its activator MT1-MMP and may, therefore, play an important role during tooth development.     

Microbiome of Deep Dentinal Caries from Reversible Pulpitis to Irreversible Pulpitis

Introduction

This study examined the identity of the microbiome of deep dentinal caries and its correlation with the inflammation status of caries-induced pulpitis.