Can we see PIP(3) and hydrogen peroxide with a single probe?

A genetically encoded sensor for parallel measurements of phosphatidylinositol 3-kinase activity and hydrogen peroxide (H(2)O(2)) levels (termed PIP-SHOW) was developed. Upon elevation of local phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) concentration, the sensor translocates from the cytosol to the plasma membrane, while a ratiometric excitation change rapidly and simultaneously reports changes in the concentration of H(2)O(2). The dynamics of PIP(3) and H(2)O(2) generation were monitored in platelet-derived growth factor-stimulated fibroblasts and in T-lymphocytes after formation of an immunological synapse. We suggest that PIP-SHOW can serve as a prototype for many fluorescent sensors with combined readouts.     

Hemodynamic Effects in Acute Cardiomyoplasty of Different Wrapped Muscle Activation Times as Measured by Pressure-Volume Relations

A bstract Background : Correct timing of mechanical interaction between wrapped latissimus dorsi muscle (LDM) and the heart during cardiac systole has been poorly understood and remains a controversial issue. Therefore, left ventricular pressure-volume relations were analyzed in acute cardiomyoplasty while changing the synchronization delays. Methods : Effects of different delays between the sensed cardiac R wave and wrapped muscle contraction were studied in goats submitted to acute left cardiomyoplasty. Conductance and micromanometer catheters were used to evaluate hemodynamics. Systolic contribution of the wrapped muscle was studied in preassisted and assisted beats, whereas diastolic effects were studied in assisted and postassisted beats. Results : At best settings, cardiomyoplasty resulted in a significant (p < 0.05) increase in left ventricular ejection fraction (from 42.2 ± 9.2 to 56.7%± 13%), in stroke work (from 2769 ± 1140 to 4271 ± 1717 gm/m²), in dP/dt (from 1185 ± 342 to 1510 ± 285 mmHg/sec), in end-systolic pressure (from 93.5 ± 22.5 mmHg to 97.3 ± 22.3 mmHg), and in peak ejection rate (from 282 ± 64 to 533 ± 241 mL/sec). Stroke volume showed a mean increase of 35% (from 42.2 ± 9.9 mL to 56.9 ± 20.1 mL) during assisted beats. Diastolic function was not substantially impaired at optimal stimulation delay. Incorrect timing of LD contraction resulted in suboptimal improvement or no change in comparison with unassisted hemodynamics. Conclusions : Our study documents support of cardiac performance by LDM. Incorrect timing of heart/wrapped muscle interaction led to suboptimal hemodynamic results. Muscle contraction timing is an important factor in cardiomyoplasty outcome.     

Patient-specific DXA bone mineral density inaccuracies: quantitative effects of nonuniform extraosseous fat distributions.

Nonuniform extraosseous fat is shown to raise the magnitude of inaccuracies in DXA in vivo BMD measurements into the range of 20-50% in clinically relevant cases. Hence, DXA-based bone fragility diagnoses/ prognoses and evaluations of bone responsiveness to treatment can be unreliable. Patient-specific DXA in vivo bone mineral areal density (BMD) measurements have been demonstrated to be inherently inaccurate even when extraosseous fat (F) and lean muscle tissue (L) are uniformly distributed throughout the scan region of interest (ROI). The present work extends these investigations to quantitative evaluation of the extent to which clinically realistic soft tissue inhomogeneities external to the bone within the DXA scan ROI affect patient-specific in vivo BMD measurement inaccuracies. The results are particularly relevant to patient-specific lumbar vertebral and proximal femoral sites. Norland, Hologic, and Lunar DXA scans and corresponding DXA simulation studies of the same set of 225 different phantom arrays were carried out. The phantoms were specially fabricated absorptiometric replications of bone mineral material (B), red marrow (RM), and yellow marrow (YM) mixtures, and extraosseous F and L combinations spanning the anthropometric ranges encountered clinically. The three different DXA scanners yielded BMD results that effectively coincided, were in excellent agreement with the findings of the present corresponding DXA-simulation studies in each case, and confirmed the validity of the DXA BMD inaccuracy analysis formalism. It was found that only relatively small extraosseous soft tissue inhomogeneities within the ROI of DXA BMD scans can increase substantially the already sizable BMD inaccuracies shown earlier to pertain for uniformly distributed extraosseous soft tissues. The extent of these in vivo BMD inaccuracies (%) are shown to depend on the mean extraosseous F-to-L areal density ratio and its degree of nonuniformity within the local bone scan ROI, the marrow thickness and specific composition, and the actual BMD in any given case. It was found that patient-specific DXA-measured in vivo BMD inaccuracies can, in many clinically encountered cases, be as large as 20-50%, particularly so for osteopenic, osteoporotic, and elderly patients. It is concluded that, because these DXA in vivo BMD inaccuracies are unavoidable and clinically unpredictable, diagnoses/ prognoses of bone fragility and evaluations of bone responsiveness to treatment of individual patients based mainly on DXA in vivo BMD measurements can be unreliable.     

A randomized,placebo‐controlled,phase 1/2 study of tivantinib (ARQ 197) in combination with irinotecan and cetuximab in patients with metastatic colorectal cancer with wild‐type KRAS who have received first‐line systemic therapy

Cetuximab in combination with an irinotecan‐containing regimen is a standard treatment in patients with KRAS wild‐type (KRAS WT), metastatic colorectal cancer (mCRC). We investigated the addition of the oral MET inhibitor tivantinib to cetuximab + irinotecan (CETIRI) based on preclinical evidence that activation of the MET pathway may confer resistance to anti‐EGFR therapy. Previously treated patients with KRAS WT advanced or mCRC were enrolled. The phase 1, open‐label 3 + 3, dose‐escalation study evaluated the safety and maximally tolerated dose of tivantinib plus CETIRI. The phase 2, randomized, double‐blinded, placebo‐controlled study of biweekly CETIRI plus tivantinib or placebo was restricted to patients who had received only one prior line of chemotherapy. The phase 2 primary endpoint was progression‐free survival (PFS). The recommended phase 2 dose was tivantinib (360 mg/m² twice daily) with biweekly cetuximab (500 mg/m²) and irinotecan (180 mg/m²). Among 117 patients evaluable for phase 2 analysis, no statistically significant PFS difference was observed: 8.3 months on tivantinib vs. 7.3 months on placebo (HR, 0.85; 95% confidence interval, 0.55–1.33; P = 0.38). Subgroup analyses trended in favor of tivantinib in patients with MET‐High tumors by immunohistochemistry, PTEN‐Low tumors, or those pretreated with oxaliplatin, but subgroups were too small to draw conclusions. Neutropenia, diarrhea, nausea and rash were the most frequent severe adverse events in tivantinib‐treated patients. The combination of tivantinib and CETIRI was well tolerated but did not significantly improve PFS in previously treated KRAS WT mCRC. Tivantinib may be more active in specific subgroups.     

Quantification of noninvasive fat reduction: A systematic review

Background and Objective

Noninvasive fat reduction appears effective, but there are various methods for quantifying changes. The objective of this review is to assess comparative utility measures of subcutaneous fat.

Study Design/Materials and Methods

Articles describing noninvasive fat reduction were searched using MEDLINE, EMBASE, CINAHL and Scopus electronic databases on two dates (January 28, 2014 and February 16, 2016). Titles of studies and abstracts were screened for eligibility. Manual review was performed by two investigators to detect those that: (1) included original data; (2) were randomized controlled trials, or prospective or retrospective cohort studies; (3) quantified fat outcomes; and (4) enrolled at least 10 subjects.

Results

Of 1,057 retrieved articles, 36 met criteria. Most reported four or more measurement techniques. Circumference measurements were most commonly cited. Other objective techniques, like caliper thickness, ultrasound, magnetic resonance imaging (MRI), and three‐dimensional (3D) photography, were also used. Common subjective methods were evaluation of standardized photographs by blinded raters and patient satisfaction surveys.

Conclusions

For quantifying noninvasive fat reduction, all available methods had significant limitations: photographic comparisons were subjective; circumference or caliper measurements were confounded; ultrasound was operator dependent; MRI was expensive; computed models and simulations were in early development. As new technologies are developed, the need for reliable, accurate and practical measures of subcutaneous fat will increase. Lasers Surg. Med. 50:96–110, 2018. © 2017 Wiley Periodicals, Inc.     

Influence of SiO2 or h-BN substrate on the room-temperature electronic transport in chemically derived single layer graphene

The substrate effect on the electronic transport of graphene with a density of defects of about 0.5% (^0.5%G) is studied. Devices composed of monolayer ^0.5%G, partially deposited on SiO₂ and h-BN were used for transport measurements. We find that the ^0.5%G on h-BN exhibits ambipolar transfer behaviours under ambient conditions, in comparison to unipolar p-type characters on SiO₂ for the same flake. While intrinsic defects in graphene cause scattering, the use of h-BN as a substrate reduces p-doping.

Defects in graphene cause scattering and basal plane interactions shift the Dirac-point.

Wet-chemically prepared graphene from graphite can be stabilized in solution by covalently bound oxo-groups using established oxidation protocols.^1–3 In general, the materials obtained are termed graphene oxide (GO). However, the chemical structure varies and the carbon lattice may even be amorphous due to the evolution of CO₂ during synthesis.⁴ Thus, in this study we use oxo-functionalized graphene (oxo-G), a type of GO with a more defined structure, as proven in our previous work.³ The oxygen-containing groups on the graphene basal plane and rims of flakes and holes make GO a p-type semiconductor with a typical resistance of 10¹⁰–10¹³ Ω sq^−1 5,6 and a band gap of about 2.2 eV.^7,8 The reductive defunctionalization of GO leads to a certain type of graphene (G), often named reduced GO (r-GO).^4,9 Removal of oxo-groups from the surface can be achieved by chemical reduction,^9,10 electrochemical methods,^11,12 electron beam treatment¹³ and was observed in situ by transmission electron microscopy.¹³ Thermal processing of GO instead leads to a disproportionation reaction forming carbon with additional vacancy defects and CO₂.¹⁴ In general, the reduction of GO turns r-GO from a semi-conductive material to a semi-metal. Mobility values were determined in field effect transistor (FET) devices.^15,16 Generally, the quality of graphene strongly depends on the integrity of the hexagonal carbon lattice. Thus, mobility values of 10⁻³ and up to 10³ cm² V⁻¹ s⁻¹ were reported,^3,17,18 with the resistance fluctuating between 10³ and 10⁶ Ω sq⁻¹.^19–21 We reported on the highest mobility values of chemically reduced oxo-G (with about 0.02% of lattice defects) of 1000 cm² V⁻¹ s⁻¹,³ determined by Hall-bar measurements at 1.6 K.Hexagonal boron nitride (h-BN) has been proved to be an excellent substrate for matching graphene-based materials owing to its atomic flatness, chemical inertness and electronic insulation due to a bandgap of ∼5.5 eV.²² Up to now, most studies with graphene deposited on h-BN were restricted to measurements with virtually defect-free graphene.²³ To the best of the authors knowledge, no studies reported transport measurements based on single layers of GO or oxo-G on h-BN substrates. No studies are reported with graphene derived from GO or oxo-G on single-layer level. Recently, we found that chemical reactions can be selectively conducted close to the rims of defects.²⁴ However, before functionalized devices can be studied, the lack of knowledge on the ambient environment device performances of graphene with defects and the influence of substrates must be addressed. Therefore, we fabricated the devices composed of ^0.5%G, partially deposited on SiO₂ (SiO₂/^0.5%G) and h-BN (h-BN/^0.5%G) (Fig. 1). Areas of the same flake on both materials are used to ensure reliable measurements and to prove that the results stem from the influence of the substrate rather than from the difference between devices. Thereby, the ^0.5%G exhibits an I_D/I_G ratio of about 3–4, corresponding to 0.5% of defects, according to the model introduced by Lucchese and Cançado.^25–28 Our results demonstrate that the h-BN layer is responsible for a downshift of the Dirac point and a more narrow hysteresis, resulting in ambipolar transfer behaviours in h-BN/^0.5%G.Open in a separate windowFig. 1(a) Optical image of the fabricated h-BN/^0.5%G heterostructure on SiO₂. (b) The h-BN/^0.5%G heterostructure device. Electrodes 1 and 2 define the SiO₂/^0.5%G FET device. Electrodes 1 and 3 define the ^0.5%G on overlapped SiO₂/h-BN hetero-substrate device. Electrodes 3 and 4 define the h-BN/^0.5%G FET device. Distance between the electrodes 1–2 and 3–4 is 1.5 μm and 3 μm, respectively. (c) 3D illustration of the h-BN/^0.5%G transistor device.