[Clinical analysis of candidemia in immunocompetent patients]

OBJECTIVE

To investigate the etiological and clinical characteristics of immunocompetent patients with candidemia.

METHODS

The clinical and microbiological data of patients diagnosed as candidemia admitted in Peking University Third Hospital from January 2010 to June 2016 were retrospectively analyzed. Underlying diseases, Candida spp. colonization, clinical manifestations, microbiological data, treatment and the outcome were compared between the HIV-negative immunocompromised (IC) and nonimmunocompromised (NIC) patients.

RESULTS

A total of 62 cases diagnosed as candidemia were analyzed including 36 men and 26 women, with 16 to 100 years of age [(66.02±17.65) years]. There were 30 NIC and 32 HIV-negative IC patients respectively. In the NIC patients, there were 19 cases (19/30, 63.33%) with admission in intensive care unit (ICU), 21 (21/30, 70.00%) associated diabetes mellitus or uncontrolled hyperglycemia and 22 (22/30,73.33%) receiving invasive mechanical ventilation, while in the HIV-negative IC patients, there were 8 (8/32, 25.00%), 13 (13/32, 40.63%) and 7 (7/32, 21.88%) respectively (P<0.05). The NIC patients had higher acute physiology and chronic health evaluation (APACHE II) scores and sequential organ failure assessment (SOFA) scores both at admission (19.98±5.81, 6.04±6.14) and candidemia onset (25.61±6.52, 12.75±8.42) than the HIV-negative IC patients (APACHEII 15.09±5.82, 22.15±5.98) and SOFA 2.87±2.73, 7.66±5.64 respectively (P<0.05). In the NIC patients, twenty-one cases (21/30, 70.00%) died in hospital, while 14 cases (14/32, 43.75%) in HIV-negative IC. The crude mortality was significantly different between the two groups (P<0.05). By blood culture, Canidia albicans remained the the most prevalent isolates in all the patients. Clinical manifestation, Candida spp. colonization, etiology and drug susceptibility were also similar between NIC and HIV-negative IC patients (P>0.05).

CONCLUSION

Candidemia in NIC patients tends to occur in those who are much more critically ill, more often admitted in ICU, and more frequently have diabetes mellitus or uncontrolled hyperglycemia and receive invasive mechanical ventilation than HIV-negative IC patients. NIC patients also have poorer prognosis than HIV-negative IC patients. Clinical manifestations, and microbiological characteristics are similar between HIV-negative IC and NIC patients.

MiR-365a-3p suppresses proliferation and invasion of Hep-2 cells through targeting ten-eleven translocation 1 (TET1)

miRNAs are among the most important factors that regulate gene expression. According to bioinformatic analysis, miR-365a-3p was predicted to interact with the TET1 mRNA. We predicted that it might affect tumor biological processes through TET1. TET1 interference and miR-365a-3p inhibitor constructs were generated. qRT-PCR was used to verify the expression level of miR-365a-3p and TET1 in Hep-2 and BESB-2B cells. qRT-PCR and Western blot were used to confirm the TET1 expression level in Hep-2 and miR-365a-3p inhibitor cells. Cell proliferation, cell cycle progression and cell invasion were further studied to identify the relationship between TET1 and miR-365a-3p. Luciferase reporter gene assays were used to find the binding site of miR-365a-3p in the 3'-UTR (3'-untranslated region) of the TET1 mRNA. TET1 was weakly expressed in Hep-2 cells and highly expressed in BESB-2B cells, while miR-143-3p and miR-365a-3p were highly expressed in Hep-2 cells and lowly expressed in BESB-2B cells. Inhibiting miR-365a-3p could up-regulate the expression of TET1. The negative effects of miR-365a-3p on cell proliferation, cell cycle progression and cell invasion could be abolished by TET1 interference. The binding site of miR-365a-3p was in the 3'-UTR of the TET1 mRNA. TET1 is one of the targets of miR-365a-3p. miR-365a-3p regulates the biological behavior of laryngeal cancer by down-regulating TET1.

Electroconductive Biohybrid Collagen/Pristine Graphene Composite Biomaterials with Enhanced Biological Activity

Electroconductive substrates are emerging as promising functional materials for biomedical applications. Here, the development of biohybrids of collagen and pristine graphene that effectively harness both the biofunctionality of the protein component and the increased stiffness and enhanced electrical conductivity (matching native cardiac tissue) obtainable with pristine graphene is reported. As well as improving substrate physical properties, the addition of pristine graphene also enhances human cardiac fibroblast growth while simultaneously inhibiting bacterial attachment (Staphylococcus aureus). When embryonic-stem-cell-derived cardiomyocytes (ESC-CMs) are cultured on the substrates, biohybrids containing 32 wt% graphene significantly increase metabolic activity and cross-striated sarcomeric structures, indicative of the improved substrate suitability. By then applying electrical stimulation to these conductive biohybrid substrates, an enhancement of the alignment and maturation of the ESC-CMs is achieved. While this in vitro work has clearly shown the potential of these materials to be translated for cardiac applications, it is proposed that these graphene-based biohybrid platforms have potential for a myriad of other applications-particularly in electrically sensitive tissues, such as neural and neural and musculoskeletal tissues.

A vicious loop of fatty acid-binding protein 4 and DNA methyltransferase 1 promotes acute myeloid leukemia and acts as a therapeutic target

Aberrant DNA methylation mediated by deregulation of DNA methyltransferases (DNMT) is a key hallmark of acute myeloid leukemia (AML), yet efforts to target DNMT deregulation for drug development have lagged. We previously demonstrated that upregulation of fatty acid-binding protein 4 (FABP4) promotes AML aggressiveness through enhanced DNMT1-dependent DNA methylation. Here, we demonstrate that FABP4 upregulation in AML cells occurs through vascular endothelial growth factor (VEGF) signaling, thus elucidating a crucial FABP4-DNMT1 regulatory feedback loop in AML biology. We show that FABP4 dysfunction by its selective inhibitor BMS309403 leads to downregulation of DNMT1, decrease of global DNA methylation and re-expression of p15INK4B tumor suppressor gene by promoter DNA hypomethylation in vitro, ex vivo and in vivo. Functionally, BMS309403 suppresses cell colony formation, induces cell differentiation, and, importantly, impairs leukemic disease progression in mouse models of leukemia. Our findings highlight AML-promoting properties of the FABP4-DNMT1 vicious loop, and identify an attractive class of therapeutic agents with a high potential for clinical use in AML patients. The results will also assist in establishing the FABP4-DNMT1 loop as a target for therapeutic discovery to enhance the index of current epigenetic therapies.

A flow bioreactor system compatible with real-time two-photon fluorescence lifetime imaging microscopy

Bioreactors are essential cell and tissue culture tools that allow the introduction of biophysical signals into in vitro cultures. One major limitation is the need to interrupt experiments and sacrifice samples at certain time points for analyses. To address this issue, we designed a bioreactor that combines high-resolution contact-free imaging and continuous flow in a closed system that is compatible with various types of microscopes. The high throughput fluid flow bioreactor was combined with two-photon fluorescence lifetime imaging microscopy (2P-FLIM) and validated. The hydrodynamics of the bioreactor chamber were characterized using COMSOL. The simulation of shear stress indicated that the bioreactor system provides homogeneous and reproducible flow conditions. The designed bioreactor was used to investigate the effects of low shear stress on human umbilical vein endothelial cells (HUVECs). In a scratch assay, we observed decreased migration of HUVECs under shear stress conditions. Furthermore, metabolic activity shifts from glycolysis to oxidative phosphorylation-dependent mechanisms in HUVECs cultured under low shear stress conditions were detected using 2P-FLIM. Future applications for this bioreactor range from observing cell fate development in real-time to monitoring the environmental effects on cells or metabolic changes due to drug applications.

Freeze-Drying as a Novel Biofabrication Method for Achieving a Controlled Microarchitecture within Large, Complex Natural Biomaterial Scaffolds

The biofabrication of large natural biomaterial scaffolds into complex 3D shapes which have a controlled microarchitecture remains a major challenge. Freeze-drying (or lyophilization) is a technique used to generate scaffolds in planar 3D geometries. Here we report the development of a new biofabrication process to form a collagen-based scaffold into a large, complex geometry which has a large height to width ratio, and a controlled porous microarchitecture. This biofabrication process is validated through the successful development of a heart valve shaped scaffold, fabricated from a collagen-glycosaminoglycan co-polymer. Notably, despite the significant challenges in using freeze-drying to create such a structure, the resultant scaffold has a uniform, homogenous pore architecture throughout. This is achieved through optimization of the freeze-drying mold and the freezing parameters. We believe this to be the first demonstration of using freeze-drying to create a large, complex scaffold geometry with a controlled, porous architecture for natural biomaterials. This study validates the potential of using freeze-drying for development of organ-specific scaffold geometries for tissue engineering applications, which up until now might not have been considered feasible.

Role of defects in laser-induced modifications of silica coatings and fused silica using picosecond pulses at 1053 nm: II. Scaling laws and the density of precursors

We investigate the role of defects in laser-induced damage of fused silica and of silica coatings produced by e-beam and PIAD processes which are used in damage resistant, multi-layer dielectric, reflective optics. We perform experiments using 1053 nm, 1-60 ps laser pulses with varying beam size, number of shots, and pulse widths in order to understand the characteristics of defects leading to laser-induced damage. This pulse width range spans a transition in mechanisms from intrinsic material ablation for short pulses to defect-dominated damage for longer pulses. We show that for pulse widths as short as 10 ps, laser-induced damage properties of fused silica and silica films are dominated by isolated absorbers. The density of these precursors and their fluence dependence of damage initiation suggest a single photon process for initial energy absorption in these precursors. Higher density precursors that initiate close to the ablation threshold at shorter pulse widths are also observed in fused silica, whose fluence and pulse width scaling suggest a multiphoton initiation process. We also show that these initiated damage sites grow with subsequent laser pulses. We show that scaling laws obtained in more conventional ways depend on the beam size and on the definition of damage for ps pulses. For this reason, coupling scaling laws with the density of precursors are critical to understanding the damage limitations of optics in the ps regime.

The role of defects in laser-induced modifications of silica coatings and fused silica using picosecond pulses at 1053 nm: I. Damage morphology

Laser-induced damage with ps pulse widths straddles the transition from intrinsic, multi-photon ionization and avalanche ionization-based ablation with fs pulses to defect-dominated, thermal-based damage with ns pulses. We investigated the morphology of damage for fused silica and silica coatings between 1 ps and 60 ps at 1053 nm. Using calibrated laser-induced damage experiments, in situ imaging, and high-resolution optical microscopy, atomic force microscopy, and scanning electron microscopy, we show that defects play an important role in laser-induced damage down to 1 ps. Three types of damage are observed: ablation craters, ultra-high density pits, and smooth, circular depressions with central pits. For 10 ps and longer, the smooth, circular depressions limit the damage performance of fused silica and silica coatings. The observed high-density pits and material removal down to 3 ps indicate that variations in surface properties limit the laser-induced damage onset to a greater extent than expected below 60 ps. Below 3 ps, damage craters are smoother although there is still evidence as seen by AFM of inhomogeneous laser-induced damage response very near the damage onset. These results show that modeling the damage onset only as a function of pulse width does not capture the convoluted processes leading to laser induced damage with ps pulses. It is necessary to account for the effects of defects on the processes leading to laser-induced damage. The effects of isolated defects or inhomogeneities are most pronounced above 3 ps but are still discernible and possibly important down to the shortest pulse width investigated here.

Steps toward Maturation of Embryonic Stem Cell-Derived Cardiomyocytes by Defined Physical Signals

Cardiovascular disease remains a leading cause of mortality and morbidity worldwide. Embryonic stem cell-derived cardiomyocytes (ESC-CMs) may offer significant advances in creating in vitro cardiac tissues for disease modeling, drug testing, and elucidating developmental processes; however, the induction of ESCs to a more adult-like CM phenotype remains challenging. In this study, we developed a bioreactor system to employ pulsatile flow (1.48 mL/min), cyclic strain (5%), and extended culture time to improve the maturation of murine and human ESC-CMs. Dynamically-cultured ESC-CMs showed an increased expression of cardiac-associated proteins and genes, cardiac ion channel genes, as well as increased SERCA activity and a Raman fingerprint with the presence of maturation-associated peaks similar to primary CMs. We present a bioreactor platform that can serve as a foundation for the development of human-based cardiac in vitro models to verify drug candidates, and facilitates the study of cardiovascular development and disease.

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Custom-made bioreactor exposes ESC-CMs to defined shear stress and cyclic stretch

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Physical signals and extended culture significantly improve maturation of ESC-CMs

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Biochemical fingerprint of dynamically cultured ESC-CMs is similar to primary CMs

Enhanced elastin synthesis and maturation in human vascular smooth muscle tissue derived from induced-pluripotent stem cells

Obtaining vascular smooth muscle tissue with mature, functional elastic fibers is a key obstacle in tissue-engineered blood vessels. Poor elastin secretion and organization leads to a loss of specialization in contractile smooth muscle cells, resulting in over proliferation and graft failure. In this study, human induced-pluripotent stem cells (hiPSCs) were differentiated into early smooth muscle cells, seeded onto a hybrid poly(ethylene glycol) dimethacrylate/poly (l-lactide) (PEGdma-PLA) scaffold and cultured in a bioreactor while exposed to pulsatile flow, towards maturation into contractile smooth muscle tissue. We evaluated the effects of pulsatile flow on cellular organization as well as elastin expression and assembly in the engineered tissue compared to a static control through immunohistochemistry, gene expression and functionality assays. We show that culturing under pulsatile flow resulted in organized and functional hiPSC derived smooth muscle tissue. Immunohistochemistry analysis revealed hiPSC-smooth muscle tissue with robust, well-organized cells and elastic fibers and the supporting microfibril proteins necessary for elastic fiber assembly. Through qRT-PCR analysis, we found significantly increased expression of elastin, fibronectin, and collagen I, indicating the synthesis of necessary extracellular matrix components. Functionality assays revealed that hiPSC-smooth muscle tissue cultured in the bioreactor had an increased calcium signaling and contraction in response to a cholinergic agonist, significantly higher mature elastin content and improved mechanical properties in comparison to the static control. The findings presented here detail an effective approach to engineering elastic human vascular smooth muscle tissue with the functionality necessary for tissue engineering and regenerative medicine applications.

STATEMENT OF SIGNIFICANCE

Obtaining robust, mature elastic fibers is a key obstacle in tissue-engineered blood vessels. Human induced-pluripotent stem cells have become of interest due to their ability to supplement tissue engineered scaffolds. Their ability to differentiate into cells of vascular lineages with defined phenotypes serves as a potential solution to a major cause of graft failure in which phenotypic shifts in smooth muscle cells lead to over proliferation and occlusion of the graft. Herein, we have differentiated human induced-pluripotent stem cells in a pulsatile flow bioreactor, resulting in vascular smooth muscle tissue with robust elastic fibers and enhanced functionality. This study highlights an effective approach to engineering elastic functional vascular smooth muscle tissue for tissue engineering and regenerative medicine applications.

Fatty acid-binding protein FABP4 mechanistically links obesity with aggressive AML by enhancing aberrant DNA methylation in AML cells

Obesity is becoming more prevalent worldwide and is a major risk factor for cancer development. Acute myeloid leukemia (AML), the most common acute leukemia in adults, remains a frequently fatal disease. Here we investigated the molecular mechanisms by which obesity favors AML growth and uncovered the fatty acid-binding protein 4 (FABP4) and DNA methyltransferase 1 (DNMT1) regulatory axis that mediates aggressive AML in obesity. We showed that leukemia burden was much higher in high-fat diet-induced obese mice, which had higher levels of FABP4 and interleukin (IL)-6 in the sera. Upregulation of environmental and cellular FABP4 accelerated AML cell growth in both a cell-autonomous and cell-non-autonomous manner. Genetic disruption of FABP4 in AML cells or in mice blocked cell proliferation in vitro and induced leukemia regression in vivo. Mechanistic investigations showed that FABP4 upregulation increased IL-6 expression and signal transducer and activator of transcription factor 3 phosphorylation leading to DNMT1 overexpression and further silencing of the p15^INK4B tumor-suppressor gene in AML cells. Conversely, FABP4 ablation reduced DNMT1-dependent DNA methylation and restored p15^INK4B expression, thus conferring substantial protection against AML growth. Our findings reveal the FABP4/DNMT1 axis in the control of AML cell fate in obesity and suggest that interference with the FABP4/DNMT1 axis might be a new strategy to treat leukemia.

Holocord spinal epidural abscess: Case report and literature review

Holocord spinal epidural abscess (SEA) is a rare condition. To our knowledge, five cases of SEA have been reported so far, and no consensus has been made on the treatment yet. In this article, we report a case of holocord SEA and review literature to further understanding of SEA. The advent of antibiotic treatment and the recognition of surgical debridement have been important in searching for alternatives to recovery, so the patient was treated surgically together with systemic antibiotics. The patient remained neurologically stable and continued to be clinically in good condition without any low back pain after 1 year. Surgical drainage, together with systemic antibiotics, is the main treatment choice for extensive SEAs. Although treatment should be considered that highlights the importance of examining the factors related to the health and condition of the patients and the anatomy and extent of the abscess, early surgical treatment associated with prolonged antibiotic treatment is necessary.

[The effect of renal clearance on serum trough concentration of vancomycin in elderly patients with severe pneumonia]

OBJECTIVE

To investigate the effect of renal clearance on serum trough concentration of vancomycin in elderly patients with severe pneumonia.

METHODS

This was a prospective non-interventional study. Forty-two elderly patients with severe pneumonia and normal level of serum creatinine were enrolled from November 2013 to October 2014. The patients included 25 males and 17 females, aged 60-83 years (median 74 years). The renal clearance was measured, and the vancomycin regimen and rate of serum trough concentration achieving guideline-recommended target of 15-20 mg/L were investigated. The factors influencing trough concentration of vancomycin were analyzed using the general linear model.

RESULTS

The vancomycin regimens were 1 g/ 12 h (17 cases), 0.5 g/8 h (14 cases) and 0.5 g/12 h (11 cases), and their median and range of serum concentrations were 14.9(2.4-28.5)mg/L, 16.2(2.8-27.8)mg/L and 11.6 (5.9-19.9) mg/L, respectively. The guideline-recommended target trough concentration of 15-20 mg/L was reached in only 10 patients, while trough concentration lower than 15 mg/L was found in 22 patients and higher than 20 mg/L in 10 patients. General linear model analysis showed that creatinine clearance rate(CCR) and dose of vancomycin per kilogram of body weight per day were independent influencing factors for trough concentration (both P<0.05). There were 8 patients with CCR≥130 ml·min(-1)·(1.73 m(2))(-1) (augmented renal clearance), 22 patients with 70≤CCR<130 ml·min(-1)·(1.73 m(2))(-1) and 12 patients with CCR<70 ml·min(-1)·(1.73 m(2))(-1,) and vancomycin trough concentration below 15 mg/L was found in 7, 11 and 4 patients, respectively.

CONCLUSION

CCR was an independent influencing factor for trough concentration of vancomycin, and augmented renal clearance increased the risk of subtherapeutic trough concentration of vancomycin.

Non-invasive Chamber-Specific Identification of Cardiomyocytes in Differentiating Pluripotent Stem Cells

One major obstacle to the application of stem cell-derived cardiomyocytes (CMs) for disease modeling and clinical therapies is the inability to identify the developmental stage of these cells without the need for genetic manipulation or utilization of exogenous markers. In this study, we demonstrate that Raman microspectroscopy can non-invasively identify embryonic stem cell (ESC)-derived chamber-specific CMs and monitor cell maturation. Using this marker-free approach, Raman peaks were identified for atrial and ventricular CMs, ESCs were successfully discriminated from their cardiac derivatives, a distinct phenotypic spectrum for ESC-derived CMs was confirmed, and unique spectral differences between fetal versus adult CMs were detected. The real-time identification and characterization of CMs, their progenitors, and subpopulations by Raman microspectroscopy strongly correlated to the phenotypical features of these cells. Due to its high molecular resolution, Raman microspectroscopy offers distinct analytical characterization for differentiating cardiovascular cell populations.

The Benefits of High Relaxivity for Brain Tumor Imaging: Results of a Multicenter Intraindividual Crossover Comparison of Gadobenate Dimeglumine with Gadoterate Meglumine (The BENEFIT Study)

BACKGROUND AND PURPOSE

Gadobenate dimeglumine (MultiHance) has higher r1 relaxivity than gadoterate meglumine (Dotarem) which may permit the use of lower doses for MR imaging applications. Our aim was to compare 0.1- and 0.05-mmol/kg body weight gadobenate with 0.1-mmol/kg body weight gadoterate for MR imaging assessment of brain tumors.

MATERIALS AND METHODS

We performed crossover, intraindividual comparison of 0.1-mmol/kg gadobenate with 0.1-mmol/kg gadoterate (Arm 1) and 0.05-mmol/kg gadobenate with 0.1-mmol/kg gadoterate (Arm 2). Adult patients with suspected or known brain tumors were randomized to Arm 1 (70 patients) or Arm 2 (107 patients) and underwent 2 identical examinations at 1.5 T. The agents were injected in randomized-sequence order, and the 2 examinations were separated by 2-14 days. MR imaging scanners, imaging sequences (T1-weighted spin-echo and T1-weighted high-resolution gradient-echo), and acquisition timing were identical for the 2 examinations. Three blinded readers evaluated images for diagnostic information (degree of definition of lesion extent, lesion border delineation, visualization of lesion internal morphology, contrast enhancement) and quantitatively for percentage lesion enhancement and lesion-to-background ratio. Safety assessments were performed.

RESULTS

In Arm 1, a highly significant superiority (P < .002) of 0.1-mmol/kg gadobenate was demonstrated by all readers for all end points. In Arm 2, no significant differences (P > .1) were observed for any reader and any end point, with the exception of percentage enhancement for reader 2 (P < .05) in favor of 0.05-mmol/kg gadobenate. Study agent-related adverse events were reported by 2/169 (1.2%) patients after gadobenate and by 5/175 (2.9%) patients after gadoterate.

CONCLUSIONS

Significantly superior morphologic information and contrast enhancement are demonstrated on brain MR imaging with 0.1-mmol/kg gadobenate compared with 0.1-mmol/kg gadoterate. No meaningful differences were recorded between 0.05-mmol/kg gadobenate and 0.1-mmol/kg gadoterate.