Advancing infection control in dental care settings: Factors associated with dentists' implementation of guidelines from the Centers for Disease Control and Prevention

Background and OverviewThe authors set out to identify factors associated with implementation by U.S. dentists of four practices first recommended in the Centers for Disease Control and Prevention's Guidelines for Infection Control in Dental Health-Care Settings—2003.MethodsIn 2008, the authors surveyed a stratified random sample of 6,825 U.S. dentists. The response rate was 49 percent. The authors gathered data regarding dentists' demographic and practice characteristics, attitudes toward infection control, sources of instruction regarding the guidelines and knowledge about the need to use sterile water for surgical procedures. Then they assessed the impact of those factors on the implementation of four recommendations: having an infection control coordinator, maintaining dental unit water quality, documenting percutaneous injuries and using safer medical devices, such as safer syringes and scalpels. The authors conducted bivariate analyses and proportional odds modeling.ResultsResponding dentists in 34 percent of practices had implemented none or one of the four recommendations, 40 percent had implemented two of the recommendations and 26 percent had implemented three or four of the recommendations. The likelihood of implementation was higher among dentists who acknowledged the importance of infection control, had practiced dentistry for less than 30 years, had received more continuing dental education credits in infection control, correctly identified more surgical procedures that require the use of sterile water, worked in larger practices and had at least three sources of instruction regarding the guidelines. Dentists with practices in the South Atlantic, Middle Atlantic or East South Central U.S. Census divisions were less likely to have complied.ConclusionsImplementation of the four recommendations varied among U.S. dentists. Strategies targeted at raising awareness of the importance of infection control, increasing continuing education requirements and developing multiple modes of instruction may increase implementation of current and future Centers for Disease Control and Prevention guidelines.The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention, Atlanta.The authors thank Jon Ruesch, who when this study was conducted was the director, Survey Center, American Dental Association, Chicago, for his effort in the collection of the data for this research project. Mr. Ruesch is now retired.     

Somatostatin receptors: From signaling to clinical practice

Somatostatin is a peptide with a potent and broad antisecretory action, which makes it an invaluable drug target for the pharmacological management of pituitary adenomas and neuroendocrine tumors. Somatostatin receptors (SSTR1, 2A and B, 3, 4 and 5) belong to the G protein coupled receptor family and have a wide expression pattern in both normal tissues and solid tumors. Investigating the function of each SSTR in several tumor types has provided a wealth of information about the common but also distinct signaling cascades that suppress tumor cell proliferation, survival and angiogenesis. This provided the rationale for developing multireceptor-targeted somatostatin analogs and combination therapies with signaling-targeted agents such as inhibitors of the mammalian (or mechanistic) target of rapamycin (mTOR). The ability of SSTR to internalize and the development of rabiolabeled somatostatin analogs have improved the diagnosis and treatment of neuroendocrine tumors.     

Mycobacterium tuberculosis heat-shock protein 70 impairs maturation of dendritic cells from bone marrow precursors, induces interleukin-10 production and inhibits T-cell proliferation in vitro

In different inflammatory disease models, heat-shock proteins (hsp) and hsp-derived peptides have been demonstrated to possess anti-inflammatory properties. While some studies have shown that hsp can directly interact with antigen-presenting cells, others report that bacterial hsp can induce specific T cells with regulatory phenotypes. Effective characterization of the immunomodulatory effects of hsp 70, however, has historically been confounded by lipopolysaccharide (LPS) contamination. In this study, we compared the effects of LPS-free Mycobacterial tuberculosis hsp 70 (TBhsp70) and its possible contaminants on dendritic cells (DC). We demonstrate herein that LPS-free TBhsp70 inhibits murine DC maturation in vitro, while LPS-contaminated TBhsp70 induces DC maturation. Mock recombinant preparations have no effect. In contrast to LPS, TBhsp70 does not induce tumour necrosis factor-alpha production by DC, but interleukin-10. In vivo, only LPS-contaminated TBhsp70 induces up-regulation of CD86 in splenic mature DC. Finally, TBhsp70 inhibited phytohaemagglutinin-induced T-cell proliferation. Our results support the hypothesis that TBhsp70 does not have inflammatory potential, but rather has immunosuppressive properties.     

Defective DNA methylation and CD70 overexpression in CD4+ T cells in MRL/lpr lupus-prone mice

We have determined that abnormal DNA methylation in T cells coincides with the development of autoimmunity, using a mouse model that exhibits an age-dependent lupus-like disease (MRL/lpr mice). Splenic CD4(+) T cells were isolated from these mice at 5 and 16 wk of age (before and after autoimmunity is established) and the expression of DNA methyltransferase 1 (Dnmt1) and the methylation-sensitive gene Tnfsf7 (CD70) was measured. Bisulfite DNA sequencing was used to monitor the methylation status of the Tnfsf7 gene. We found that Dnmt1 steady-state mRNA levels were significantly lower in 16-wk-old MRL/lpr mice, which had established autoimmunity, compared to the 5-wk-old MRL/lpr mice. Furthermore, the expression of CD70 was higher in MRL/lpr mice at 16 wk. CD70 was overexpressed in MRL/lpr mice compared to age- and sex-matched MRL(+/+) controls. Bisulfite DNA sequencing of the Tnfsf7 gene in MRL/lpr mice revealed that at 16 wk, CG pairs were hypomethylated compared to 5-wk-old mice, and that Tnfsf7 from MRL/lpr mice was hypomethylated at 16 wk relative to age-matched MRL(+/+) controls. Our data indicate that decreased expression of Dnmt1 and the corresponding T cell DNA hypomethylation correlate with the development of age-dependent autoimmunity in MRL/lpr mice.     

Salidroside exerts angiogenic and cytoprotective effects on human bone marrowderived endothelial progenitor cells via Akt/mTOR/p70S6K and MAPK signalling pathways

Background and Purpose

With the increase of age, increased susceptibility to apoptosis and senescence may contribute to proliferative and functional impairment of endothelial progenitor cells (EPCs). The aim of this study was to investigate whether salidroside (SAL) can induce angiogenic differentiation and inhibit oxidative stress-induced apoptosis in bone marrow-derived EPCs (BM-EPCs), and if so, through what mechanism.

Experimental Approach

BM-EPCs were isolated and treated with different concentrations of SAL for up to 4 days. Cell proliferation, migration and tube formation ability were detected by DNA content quantification, transwell assay and Matrigel-based angiogenesis assay. Gene and protein expression were assessed by qRT-PCR and Western blot respectively.

Key Results

Treatment with SAL promoted cellular proliferation and angiogenic differentiation of BM-EPCs, and increased VEGF and NO secretion, which in turn mediated the enhanced angiogenic differentiation of BM-EPCs. Furthermore, SAL significantly attenuated hydrogen peroxide (H₂O₂)-induced cell apoptosis, reduced the intracellular level of reactive oxygen species and restored the mitochondrial membrane potential of BM-EPCs. Moreover, SAL stimulated the phosphorylation of Akt, mammalian target of rapamycin and p70 S6 kinase, as well as ERK1/2, which is associated with cell migration and capillary tube formation. Additionally, SAL reversed the phosphorylation of JNK and p38 MAPK induced by H₂O₂ and suppressed the changes in the Bax/Bcl-xL ratio observed after stimulation with H₂O₂.

Conclusions and Implications

These findings identify novel mechanisms that regulate EPC function and suggest that SAL has therapeutic potential as a new agent to enhance vasculogenesis as well as protect against oxidative endothelial injury.     

Single-molecule spectroscopy reveals chaperone-mediated expansion of substrate protein

Molecular chaperones are an essential part of the machinery that avoids protein aggregation and misfolding in vivo. However, understanding the molecular basis of how chaperones prevent such undesirable interactions requires the conformational changes within substrate proteins to be probed during chaperone action. Here we use single-molecule fluorescence spectroscopy to investigate how the DnaJ–DnaK chaperone system alters the conformational distribution of the denatured substrate protein rhodanese. We find that in a first step the ATP-independent binding of DnaJ to denatured rhodanese results in a compact denatured ensemble of the substrate protein. The following ATP-dependent binding of multiple DnaK molecules, however, leads to a surprisingly large expansion of denatured rhodanese. Molecular simulations indicate that hard-core repulsion between the multiple DnaK molecules provides the underlying mechanism for disrupting even strong interactions within the substrate protein and preparing it for processing by downstream chaperone systems.Maintaining protein homeostasis in vivo requires a tight regulation of protein folding to prevent misfolding and aggregation. Molecular chaperones have evolved as an essential part of the cellular machinery that facilitates such processes in the complex and crowded environment of a living cell (1, 2). To assist protein folding, many chaperones proceed through complex conformational cycles in an ATP-dependent manner (3–5). For several chaperone systems, these cycles have been investigated in great detail by experiment and simulation (6–8). A remarkable example are the heat shock protein (Hsp) 70 chaperones, which are essential in prokaryotes and eukaryotes and are involved in co-translational folding, refolding of misfolded and aggregated proteins, protein translocation, and protein degradation (9). The Hsp70 chaperone DnaK from Escherichia coli together with its co-chaperone DnaJ and the nucleotide exchange factor GrpE form an ATP-driven catalytic reaction cycle (7) (Fig. 1A). Many denatured or misfolded substrate proteins are first captured by DnaJ and subsequently transferred to the DnaK–ATP complex, with DnaK in an open conformation. Substrate and DnaJ synergistically trigger DnaK’s ATPase activity, which leads to locking of the substrate in the DnaK–ADP complex, with DnaK in the closed conformation. Driven by the following GrpE-catalyzed ADP–ATP exchange, the DnaK–substrate complex dissociates (10). Since this ATP-driven cycle can even solubilize protein aggregates (11, 12), substantial forces must be transduced to the substrate protein (13–15). However, as for other chaperone systems (16), surprisingly little is known about how these forces and the resulting constraints of the underlying free energy surfaces affect the conformations of the denatured or misfolded substrate proteins. To better understand this important link between chaperone action and function, we probed the conformation of a substrate protein along the different stages of the chaperone cycle of DnaK with single-molecule Förster resonance energy transfer (smFRET), correlation spectroscopy, and microfluidic mixing.Open in a separate windowFig. 1.DnaK expands the denatured substrate protein. (A) Illustration of the DnaK–ATPase cycle. (B) Surface representation of rhodanese (PDB ID code 1RHS) with the subdomains indicated in different gray levels and the label positions of fluorescent dyes for single-molecule FRET measurements shown schematically. (C) FRET efficiency histograms of native rhodanese (gray) and denatured rhodanese under native conditions transiently populated in the microfluidic mixer (colored, measured 125 ms after dilution of rhodanese into native conditions). (D) FRET efficiency histograms of DnaJ–rhodanese complexes (0.5 µM DnaJ). (E) FRET efficiency histograms of DnaK–rhodanese complexes (0.5 µM DnaJ, 10 µM DnaK, and 1 mM ATP; DnaK and DnaJ were added simultaneously to rhodanese). Black lines indicate the DnaK–rhodanese complex population resulting from a fit that takes into account the residual population of refolded and DnaJ-bound rhodanese. The vertical lines in C–E indicate the positions of the FRET efficiency peaks of the native population of the respective rhodanese variants. The small populations at zero transfer efficiency in D (note the axis scaling and the small amplitudes of this population compared with E) originate from incomplete elimination of molecules with inactive acceptor fluorophores by pulsed interleaved excitation.     

CD70在非小细胞肺癌治疗中的潜在作用

CD70是肿瘤坏死因子受体(tumor necrosis factor receptor,TNFR)超家族的成员之一,目前的研究证实CD70主要表达于B细胞、活化的T细胞及成熟的树突状细胞中.CD70还高水平表达于多种血液肿瘤和实体瘤,使其可能成为肿瘤免疫治疗的潜在靶点.在过去的几十年,免疫学的进步使免疫检查点得以确定,这使得癌症免疫治疗再度成为热点.现就CD70在非小细胞肺癌(non-small cell lung cancer,NSCLC)中的相关研究进行回顾与总结,以期为CD70在NSCLC中的免疫治疗提供参考和研究依据.     

来曲唑联合地塞米松对多囊卵巢综合征患者血清Galectin-3及HSP70的影响

目的 探讨来曲唑联合地塞米松对多囊卵巢综合征(PCOS)患者血清半乳糖凝集素-3(Galectin-3)及热休克蛋白(HSP70)表达的影响。方法 选择2019年6月—2021年6月在我院治疗的PCOS患者220例为研究对象,按随机数表法分为对照组(n=110)和观察组(n=110),对照组常规给予来曲唑治疗。观察组在对照组的基础上加用地塞米松联合治疗。观察并比较两组患者的激素水平,促排卵情况,血清抗苗勒管激素(AMH)、Galectin-3、HSP70及单核细胞趋化蛋白-1(MCP-1)水平及不良反应发生率。结果 治疗后两组患者的性激素水平均改善,且观察组变化幅度高于对照组(P<0.05)。观察组患者雌二醇(E₂)用量低于对照组,成熟卵泡数量和最大卵泡直径均高于对照组(均P<0.05)。两组患者的早期流产率差异无统计学意义(P>0.05);观察组患者的妊娠率高于对照组(P<0.05)。治疗前两组患者AMH、Galectin-3、HSP70、MCP-1水平差异无统计学意义(P>0.05),治疗后两组患者的AMH、Galectin-3、...     

Infarct tolerance accompanied enhanced BDNF-like immunoreactivity in neuronal nuclei

A prolonged period (48 h) of cortical spreading depression (CSD) induced resistance against severe focal cerebral ischemia (infarct tolerance), however, the mechanism behind this is unknown. The infarct tolerance was a transient phenomenon; the resistance increased linearly for the initial 12 days, peaking from 12 to 15 days after a preconditioning of CSD, and was decreased thereafter. This study examined the time course of brain-derived neurotrophic factor (BDNF), heat shock protein (hsp)27 and 70, and glial fibrillary acidic protein (GFAP) expressions after CSD in the brain. Immunohistochemical expression of BDNF, hsp27, hsp70, or GFAP following a prolonged period of CSD induced by KCl-infusion, or following NaCl-infusion was analyzed by regional densitometry for 24 days in the rat neocortex. In addition, BDNF protein was measured quantitatively by two-site ELISA assay in the neocortex (n=6 at each time point). The GFAP expression was elevated in astrocytes (compared to the normal level of immunodensity) during the period peaking on day 3-6 following the CSD. The hsp27 immunoreactivity was also elevated in astrocytes from day 1 to 12 peaking on day 1 and 6, but there was no expression of hsp70 during the period following CSD. The immunoreactivity for BDNF was elevated in neurons from day 0 to 18 peaking on day 1 and 6. The protein levels of BDNF in the neocortex were significantly elevated from day 0 to 12 peaking on days 0 and 6 (compared to the normal level) (P<0.05). Using a laser-scanning confocal imaging system, the BDNF-like immunoreactivity in neuronal nuclei was found to increase linearly peaking on day 12, which correlated well with the development of infarct tolerance. The intranuclear increase in BDNF-like protein might contribute to the induction of infarct tolerance in the brain.