The relation of diabetic control to in vivo pH of soft tissue abscesses

Silencing of SAA1 inhibits palmitate- or high-fat diet induced insulin resistance through suppression of the NF-κB pathway

Background

Obesity is one of the leading causes of insulin resistance. Accumulating reports have highlighted that serum amyloid A-1 (SAA1) is a potential candidate that is capable of attenuating insulin resistance. Hence, we conducted the current study with aims of investigating our proposed hypothesis that silencing SAA1 could inhibit the progression of obesity-induced insulin resistance through the NF-κB pathway.

Methods

Gene expression microarray analysis was initially performed to screen differentially expressed genes (DEGs) associated with obesity. Palmitate (PA)-induced insulin resistance Huh7 cell models and high-fat diet (HFD)-induced mouse models were established to elucidate the effect of SAA1/Saa1 on insulin resistance. The NF-κB pathway-related expression was subsequently determined through the application of reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis.

Results

Saa1 was identified as an obesity-related gene based on the microarray data of GSE39549. Saa1 was determined to be highly expressed in HFD-induced insulin resistance mouse models. PA-induced Huh7 cells, treated with silenced SAA1 or NF-κB pathway inhibition using BAY 11–7082, displayed a marked decrease in both Saa1 and SOCS3 as well as an elevation in 2DG, IRS1 and the extent of IRS1 phosphorylation. HFD mice treated with silenced Saa1 or inhibited NF-κB pathway exhibited improved fasting blood glucose (FBG) levels as well as fasting plasma insulin (FPI) levels, glucose tolerance and systemic insulin sensitivity. Saa1/SAA1 was determined to show a stimulatory effect on the transport of the NF-κBp65 protein from the cytoplasm to the nucleus both in vivo and in vitro, suggesting that Saa1/SAA1 could activate the NF-κB pathway.

Conclusion

Taken together, our key findings highlight a novel mechanism by which silencing of SAA1 hinders PA or HFD-induced insulin resistance through inhibition of the NF-κB pathway.

Electronic supplementary material

The online version of this article (10.1186/s10020-019-0075-4) contains supplementary material, which is available to authorized users.

In vitro Characteristics of a Glass Ionomer Cement

Glass ionomer cements were first described by Wilson and Kent and have been used in dentistry since 1969. It has been recommended for bridging ossicular chain defects, fixation of ossicular chain prosthesis, anchoring of cochlear implants, mastoid obliteration, and repair of tegmen and posterior canal wall defects. The biocompatability and stability of this material over time is vital to its usefulness in neurotologic surgery. The purpose of this study was to assess the stability of a glass ionomer cement in the presence of bacteria and in different pH environments. We demonstrated that bacteria readily adhere to the surface and their presence is associated with accelerated loss of matrix. We found the cement to be susceptible to low pH and to release a visible cloud of debris upon contact with fluid. Calcium concentration in the solution was elevated at all pH levels. Although we are able to demonstrate these findings in vitro the clinical relevance is unclear. There have been several cases of aseptic meningitis possibly due to intracranial release of components of the cement. Until further studies are done use of the cement in contact with cerebral spinal fluid should be avoided. This cement, or a similar material, would be useful in neurotologic surgery but prior to widespread use further testing should be done to assess safety.

Intracellular pH regulation in U937 human monocytes: roles of V-ATPase and Na+/H+ exchange

The role of plasmalemmal V-type H+ translocating ATPase (V-ATPase) in regulation of intracellular pH (pHi) is unclear in monocytes. This study examined the plasmalemmal V-ATPase and Na+/H+ exchanger (NHE) in U937 human monocytes. The fluorescent probe 2',7'-biscarboxyethyl-5,6-carboxyfluorescein was used to monitor baseline pHi and the kinetics of pHi recovery from cytosolic acid-loads (NH4Cl prepulse). Bafilomycin A1 and 5-(N-ethyl-N-isopropyl)amiloride (EIPA) were used to delineate the activities of the H+-pump and NHE, respectively. Baseline pHi was approximately 7.13 at an extracellular pH (pHo) of 7.4 and fell progressively at lower pHo values. EIPA had no effect on baseline pHi at pHo 7.4, but caused a sustained decrement in pHi at pHo 6.0-7.0. Bafilomycin A1 had biphasic effects on baseline pHi at pHo 6.5-7.4; pHi declined approximately 0.1 units over the course of several minutes and then recovered. At pHo 6.0, bafilomycin A1 caused a sustained decrement in baseline pHi. Recovery from the bafilomycin-induced acidosis at pHo 6.5-7.4 was prevented by EIPA. Similarly, pHi recovery from NH4Cl prepulse acid-loads (pHo 7.4) was sensitive to both EIPA and bafilomycin A1. During this recovery process, Na+/H+ exchange (EIPA-sensitive component of apparent H+ efflux) was the predominant mechanism for H+ extrusion at acid-loaded pHi values < 7.0. At acid-loaded pHi values > or = 7.0, the V-ATPase (bafilomycin-sensitive component) and NHE contributed almost equally to H+ extrusion. The data provide the first evidence that plasmalemmal V-ATPase participates in pHi regulation in U937 cells. The H+-pump and NHE interacted to set baseline pHi and for pHi recovery following cytosolic acid-loading of the monocytes.

Dissociation of indium from indium-111-labelled diethylene triamine penta-acetic acid conjugated non-specific polyclonal human immunoglobulin G in inflammatory foci

Several investigators have reported retention of indium-111 in infectious foci after intravenous injection of 111In-labelled immunoglobulin G (IgG). With this study we intended to test the hypothesis that, upon administration of 111In-diethylene triamine penta-acetic acid (DTPA-IgG), 111In is retained in the infectious foci after dissociation from IgG. Therefore we measured the tissue distribution of double-labelled 111In-DTPA-IgG-(carbon-14) in rats with a focal infection and compared the results with corresponding data for DTPA-IgG-(14C). DTPA-conjugated IgG was labelled with 111In via citrate transchelation. 111In-DTPA-IgG and DTPA-IgG were labelled with 14C through methylation. High-performance liquid chromatography (HPLC) and instant thin-layer chromatography analysis were performed to test the in vitro stability of the labelled proteins. Young Wistar rats with a Staphylococcus aureus infection of the left calf muscle were injected intravenously with 0.2 ml of a solution containing either 0.4 MBq 111In and 30 kBq 14C or 30 kBq 14C labelled to 80 micrograms IgG. Groups of five rats were sacrificed at 2, 6, 24, and 48 h. p.i. Activity uptake was determined for plasma, urine, abscess, muscle and various other tissues. Averages and standard deviations were calculated for groups of five rats. HPLC analysis was performed on plasma and urine samples taken up to 48 h p.i. The radiochemical purity of the IgG preparations was > 95%. The labelled preparations appeared stable in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Infections in the diabetic patient: the role of immune dysfunction and pathogen virulence factors

It is a common belief that certain infections occur more frequently in patients with diabetes mellitus than in nondiabetics. In some infections, poor diabetic control is strongly linked. Diabetics comprise 50%-70% of all patients who undergo nontraumatic foot or leg amputations, the overwhelming majority of which are necessitated by infection and necrosis of soft tissue and/or bone. Imputed host defense abnormalities include defective immune responses (e.g., white blood cell function, granuloma formation), peripheral neuropathies, impaired distal arterial supply, and problems in "control" of the diabetic state eventuating in catabolic metabolism. Increased bacterial translocation as a source of the causative bacteria is another potential entry site. Possible virulence factors of the invading organisms include polymicrobial synergism, glycocalyx formation, and inoculum size. Attention to the principles of preventive education, vascular evaluation, diabetes management, and adequate debridement maximize healing potential.