Hasil untuk "physics.bio-ph"

Xiaoxin Zou, Xiaoxi Huang, A. Goswami et al.

Juan Liu, Yuran Huang, Anil Kumar et al.

D. Neri, C. Supuran

Niels Holten-Andersen, Matthew J. Harrington, H. Birkedal et al.

Ying-hong Guan, Jun Ma, Xu-chun Li et al.

Junyan Han, K. Burgess

Congcong Shen, J. Xiong, Huayong Zhang et al.

J. Rousk, P. Brookes, E. Bååth

I. Parolini, C. Federici, C. Raggi et al.

Exosomes secreted by normal and cancer cells carry and deliver a variety of molecules. To date, mechanisms referring to tumor exosome trafficking, including release and cell-cell transmission, have not been described. To gain insight into this, exosomes purified from metastatic melanoma cell medium were labeled with a lipid fluorescent probe, R18, and analyzed by spectrofluorometry and confocal microscopy. A low pH condition is a hallmark of tumor malignancy, potentially influencing exosome release and uptake by cancer cells. Using different pH conditions as a modifier of exosome traffic, we showed (i) an increased exosome release and uptake at low pH when compared with a buffered condition and (ii) exosome uptake by melanoma cells occurred by fusion. Membrane biophysical analysis, such as fluidity and lipid composition, indicated a high rigidity and sphingomyelin/ganglioside GM3 (N-acetylneuraminylgalactosylglucosylceramide) content in exosomes released at low pH. This was likely responsible for the increased fusion efficiency. Consistent with these results, pretreatment with proton pump inhibitors led to an inhibition of exosome uptake by melanoma cells. Fusion efficiency of tumor exosomes resulted in being higher in cells of metastatic origin than in those derived from primary tumors or normal cells. Furthermore, we found that caveolin-1, a protein involved in melanoma progression, is highly delivered through exosomes released in an acidic condition. The results of our study provide the evidence that exosomes may be used as a delivery system for paracrine diffusion of tumor malignancy, in turn supporting the importance of both exosomes and tumor pH as key targets for future anti-cancer strategies.

G. Nicol, S. Leininger, C. Schleper et al.

G. W. Thomas

Soil pH is probably the single most informative measurement that can be made to determine soil characteristics. At a single glance, pH tells much more about a soil than merely indicating whether it is acidic or basic. For example, availability of essential nutrients and toxicity of other elements can be estimated because of their known relationship with pH. The term pH was "invented" by the Swedish scientist Sorensen (1909) in order to obtain more convenient numbers and the idea quickly caught on. Gillespie and Hurst (1918) seem to have been among the earliest to determine pH (or PH, as it was then called) electrometrically using a platinum-palladium blackhydrogen gas electrode, a calomel reference electrode and a fairly cumbersome potentiometer and galvanometer system. At that period, it was still much more common to use colorimetric methods with indicator dyes than the electrometric method. This changed rapidly, however. Sharp and Hoagland (1919) used a similar but less involved method than Gillespie and Hurst (1918) and Healy and Karraker (1922) used a commercially available platinum-hydrogen gas electrode, potentiometer and galvanometer which had been designed by Clark (1920). The decade of the 1920s saw the development of the quinhydrone electrode which was less fragile and much less expensive than the hydrogen-platinum electrode. But, it was the development of the glass electrode in the 1930s that brought the determination of pH very rapidly to its present importance and convenience. The Beckman Model G pH meter (circa 1931) was practically indestructible and could be used as a portable as well as a laboratory instrument. Although it was cumbersome by today's standards, it was virtually foolproof (except for the constantly failing batteries) and many are still capable of operating if not actually operating today. As recently as two decades ago, the use of the small, handheld portable pH meters then available to determine pH in the field was a very imprecise and hazardous undertaking because both electrodes and meters were subject to sudden failures but this has changed rather abruptly in the last few years. Microcircuitry and plastic have contributed to rugged pH meters and electrodes that withstand

K. Caldeira, M. Wickett, P. Duffy et al.

P. Gupta, K. Vermani, S. Garg

G. Helmlinger, F. Yuan, M. Dellian et al.

N. Tanner, Yinhua Zhang, T. C. Evans

Nucleic acid amplification is the basis for many molecular diagnostic assays. In these cases, the amplification product must be detected and analyzed, typically requiring extended workflow time, sophisticated equipment, or both. Here we present a novel method of amplification detection that harnesses the pH change resulting from amplification reactions performed with minimal buffering capacity. In loop-mediated isothermal amplification (LAMP) reactions, we achieved rapid (<30 min) and sensitive (<10 copies) visual detection using pH-sensitive dyes. Additionally, the detection can be performed in real time, enabling high-throughput or quantitative applications. We also demonstrate this visual detection for another isothermal amplification method (strand-displacement amplification), PCR, and reverse transcription LAMP (RT-LAMP) detection of RNA. The colorimetric detection of amplification presented here represents a generally applicable approach for visual detection of nucleic acid amplification, enabling molecular diagnostic tests to be analyzed immediately without the need for specialized and expensive instrumentation.

Volkan Yesilyurt, M. Webber, Eric A. Appel et al.

Chuanxi Wang, zhenzhu xu, Hao Cheng et al.

M. Koziolek, M. Grimm, D. Becker et al.

Christopher C. Deng, William L. A. Brooks, K. Abboud et al.

Sunder Neelakantan, Tanmay Mukherjee, Emilio A. Mendiola et al.

Pulmonary hypertension (PH) can lead to significant vascular remodeling, resulting in altered pulmonary blood flow. Estimating the patient-specific contributions of each remodeling event is necessary to optimize and individualize clinical intervention strategies. In-silico modeling has emerged as a powerful tool to simulate pulmonary hemodynamics, and one of the primary requirements for robust in-silico modeling is an accurate representation of the pulmonary vasculature structure. Computed tomography (CT) imaging can be used to segment and reconstruct the proximal vasculature. However, contrast-enhanced imaging, such as CT pulmonary angiography, is required to obtain a comprehensive and high-fidelity view of the pulmonary vasculature. The clinical use of CT pulmonary angiography is limited by the complications associated with the injection of contrast agents. Machine learning (ML) approaches have emerged to effectively segment and reconstruct the pulmonary vasculature without the need for contrast-enhanced imaging. We have developed a method to create in-silico pulmonary angiogram phantoms with varying simulated contrast levels. The results indicated that adding simulated contrast can allow for successful segmentation of the pulmonary vasculature. We expect this method to assist with developing and training ML-based segmentation frameworks and aid in their validation, thereby improving the capability to segment and reconstruct pulmonary vasculature without using contrast-enhanced imaging.