Hasil untuk "physics.space-ph"

H. Birks, J. Line, S. Juggins et al.

Eun Seong Lee, Zhong-gao Gao, Y. Bae

F. Gallagher, M. Kettunen, S. Day et al.

H. Lambers, S. Piessens, A. Bloem et al.

T. D. Brock, K. M. Brock, R. Belly et al.

J. Chiche, K. Ilc, Julie Laferrière et al.

Acidosis of the tumor microenvironment is typical of a malignant phenotype, particularly in hypoxic tumors. All cells express multiple isoforms of carbonic anhydrase (CA), enzymes catalyzing the reversible hydration of carbon dioxide into bicarbonate and protons. Tumor cells express membrane-bound CAIX and CAXII that are controlled via the hypoxia-inducible factor (HIF). Despite the recognition that tumor expression of HIF-1alpha and CAIX correlates with poor patient survival, the role of CAIX and CAXII in tumor growth is not fully resolved. To understand the advantage that tumor cells derive from expression of both CAIX and CAXII, we set up experiments to either force or invalidate the expression of these enzymes. In hypoxic LS174Tr tumor cells expressing either one or both CA isoforms, we show that (a) in response to a "CO(2) load," both CAs contribute to extracellular acidification and (b) both contribute to maintain a more alkaline resting intracellular pH (pH(i)), an action that preserves ATP levels and cell survival in a range of acidic outside pH (6.0-6.8) and low bicarbonate medium. In vivo experiments show that ca9 silencing alone leads to a 40% reduction in xenograft tumor volume with up-regulation of ca12 mRNA levels, whereas invalidation of both CAIX and CAXII gives an impressive 85% reduction. Thus, hypoxia-induced CAIX and CAXII are major tumor prosurvival pH(i)-regulating enzymes, and their combined targeting shows that they hold potential as anticancer targets.

S. Duncan, P. Louis, J. Thomson et al.

M. Schmid-Wendtner, H. Korting

The ‘acid mantle’ of the stratum corneum seems to be important for both permeability barrier formation and cutaneous antimicrobial defense. However, the origin of the acidic pH, measurable on the skin surface, remains conjectural. Passive and active influencing factors have been proposed, e.g. eccrine and sebaceous secretions as well as proton pumps. In recent years, numerous investigations have been published focusing on the changes in the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. The pH of the skin follows a sharp gradient across the stratum corneum, which is suspected to be important in controlling enzymatic activities and skin renewal. The skin pH is affected by a great number of endogenous factors, e.g. skin moisture, sweat, sebum, anatomic site, genetic predisposition and age. In addition, exogenous factors like detergents, application of cosmetic products, occlusive dressings as well as topical antibiotics may influence the skin pH. Changes in the pH are reported to play a role in the pathogenesis of skin diseases like irritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections. Therefore, the use of skin cleansing agents, especially synthetic detergents with a pH of about 5.5, may be of relevance in the prevention and treatment of those skin diseases.

R. Feely, S. Alin, J. Newton et al.

H. Bai, Chun Xing Li, Xiaolin Wang et al.

Souvik Modi, S. M. G., D. Goswami et al.

Faheem Muhammad, Mingyi Guo, Wenxiu Qi et al.

Xiaomeng Zhang, Yuxiang Lin, R. Gillies

I. Robey, B. Baggett, N. Kirkpatrick et al.

C. Cornwall, C. Hepburn, C. McGraw et al.

C. Sundberg, Dan Yu, I. Franke‐Whittle et al.

Highlights ► High odour emission from food waste compost was correlated to low pH. ► Microbes in high-odour samples included Lactic acid bacteria and Clostridia. ► For odour prevention, try high initial aeration rate and recycled compost as additive.

Dhammika Weerakkody, A. Moshnikova, Mak S. Thakur et al.

T. H. Nguyen, Thillainathan Venugopala, Shuying Chen et al.

The design, development and evaluation of an optical fibre pH sensor for monitoring pH in the alkaline region are discussed in detail in this paper. The design of this specific pH sensor is based on the pH induced change in fluorescence intensity of a coumarin imidazole dye which is covalently attached to a polymer network and then fixed to the distal end of an optical fibre. The sensor provides a response over a pH range of 10.0–13.2 with an acceptable response rate of around 50 min, having shown a very good stability over a period of longer than 20 months thus far. The sensor has also demonstrated little cross-sensitivity to ionic strength (IS) and also excellent photostability through a series of laboratory tests. These features make this type of sensor potentially well suited for in situ long term monitoring of pH in concrete structures, to enhance structural monitoring in the civil engineering sector.

A. Martinière, E. Bassil, É. Jublanc et al.

J. Beattie, Alex M. Djerdjev, Angus A Gray-Weale et al.