Bcl-xL as a Modulator of Senescence and Aging

Many features of aging result from the incapacity of cells to adapt to stress conditions. When cells are overwhelmed by stress, they can undergo senescence to avoid unrestricted growth of damaged cells. Recent findings have proven that cellular senescence is more than that. A specific grade of senescence promotes embryo development, tissue remodeling and wound healing. However, constant stresses and a weakening immune system can lead to senescence chronicity with aging. The accumulation of senescent cells is directly related to tissue dysfunction and age-related pathologies. Centenarians, the most aged individuals, should accumulate senescent cells and suffer from their deleterious effects, however, they enjoy a compression of morbidity. We have shown that they overexpress B-cell lymphoma-extra large (Bcl-xL). Bcl-xL could avoid an excessive burden of senescent cells through the regulation of intrinsic apoptosis, mitochondrial bioenergetics and oxidative stress. On the other hand, Bcl-xL maintains a fully functional immune system that ensures an efficient clearance of senescent cells. Moreover, there is a paradox, as inhibitors of Bcl-xL have been employed as senolytic agents, which have been shown to protect from aging in animal models. In this review, we aim to discuss how Bcl-xL could modulate senescence-associated harmful effects in centenarians, protecting them from the burden of accumulation of senescent cells.     

Gastroprotective effect of a type I arabinogalactan from soybean meal

A highly purified type I arabinogalactan (AG) from soybean meal was prepared. It contained galactose, arabinose, galacturonic acid and rhamnose in a 52:41:4:3 molar ratio and had M_w 124,000 g/mol. Methylation analysis and ¹³C NMR spectroscopy indicated that AG is constituted by a (1→4)-linked β-Galp main chain with substituents of α-Araf at O-3, which are in turn substituted at O-5, O-3,5, and O-2,5. It is probably linked to O-4 of some rhamnosyl units of a type I rhamnogalacturonan, formed by repeating (1→4)-α-D-GalpA-(1→2)-α-L-Rhap groups. AG significantly inhibited ethanol-induced gastric lesions in rats at an ED₅₀ of 35 mg/kg, indicating that it has a gastroprotective effect.     

Determination of the viability of Toxoplasma gondii in cured ham using bioassay: influence of technological processing and food safety implications

Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii and distributed worldwide. Ingestion of viable cysts from infected raw or undercooked meat is an important route of horizontal transmission of the parasite to humans. Little information is available concerning the effect of commercial curing on cysts of T. gondii. This study is the first in which the influence of processing of cured ham on the viability of T. gondii has been evaluated, using bioassay to assess the risk of infection from eating this meat product. Naturally infected pigs were selected for the study, and a mouse concentration bioassay technique was used to demonstrate viable bradyzoites of T. gondii in porcine tissues and hams. No viable parasites were found in the final product (14 months of curing) based on results of the indirect immunofluorescence assay and histological and PCR analyses. Our results indicate that the consumption of hams cured as described here poses an insignificant risk of acquiring toxoplasmosis. However, additional studies are required to evaluate the safety of ham products cured under different conditions of curing time, salt, and nitrite concentration.     

Comparative study of the mineral composition of several varieties of potatoes (Solanum tuberosum L.) from different countries cultivated in Canary Islands (Spain)

Potatoes are a basic component of human diets worldwide being an excellent source of minerals linked the maintenance of health. Contents of calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), cupper (Cu), iron (Fe), manganese (Mn), zinc (Zn), nickel (Ni) and chromium (Cr) in seventy‐four fresh potato samples from different varieties consumed in Tenerife Island (Canary Islands, Spain) were determined by flame atomic absorption spetrometry (FAAS). The mean concentrations were 60.1 mg kg^?1, 222 mg kg^?1, 5047 mg kg^?1, 125 mg kg^?1, 1.69 mg kg^?1, 8 mg kg^?1, 1.70 mg kg^?1, 3.88 mg kg^?1, 62.7 μg kg^?1 and 19.9 μg kg^?1 for Ca, Mg, K, Na, Cu, Fe, Mn, Zn, Ni and Cr, respectively. The varieties of local potatoes presented higher mineral contents than imported potatoes. Potassium presented the highest contents in all varieties of potatoes. Iron was the most abundant microelement. Local potatoes offer greater nutritional contributions to the recommended intakes than imported varieties. Within the macrominerals, the highest contribution to the intakes was observed for K, while Fe was the trace element with the largest contribution to the proposed intake.     

Microbiological and sensory changes in "Morcilla de Burgos" preserved in air, vacuum and modified atmosphere packaging

"Morcilla de Burgos" is the most popular blood sausage in Spain. Traditionally, this product is distributed and sold without packaging in the local market. To extend its shelf-life and expand the market, different packaging methods have been employed and compared: "morcilla" stored in air (without packaging), in vacuum and in modified atmosphere packaging (MAP) using three different CO(2) concentrations 30%, 50% and 80% and balanced with N(2). Total viable count (TVC), psychrotrophs, lactic acid bacteria (LAB), pseudomonads, enterobacteria, moulds and yeasts, enterococci, Staphylococcus aureus, and sulfite reducing clostridia were analysed during storage at 4°C. Sulfite-reducing clostridia, pathogenic staphylococci, and enterococci were not detected in any sample. In air-stored "morcilla" a significant increase in all microbial groups was observed during storage. Pseudomonads were the predominant microorganisms reaching a population higher than 8 log cfu/g after 27 days of storage. On the other hand, a decrease in pH was noticed in MAP and in vacuum packaged "morcilla" (pH 4.73) during storage. At the same time, LAB becomes the predominant species in all these packaged samples. The rest of the microbiota did not grow during storage. In "morcilla" packed with 50% and 80% of CO(2), counts of pseudomonads and enterobacteria were lower than found in the vacuum packs. Sensory analysis showed that shelf-life of "morcilla" stored in air did not exceed 17 days, while samples packed under vacuum and with 30% CO(2) were acceptable until 22 days of storage. "Morcillas" packaged with 50% and 80% CO(2) were sensorially acceptable for 32 days.     

Central thickness of hydrogel contact lenses as a predictor of success when fitting patients with tear deficiency.

A randomized, double masked, study was designed in order to investigate the relationship between the central thickness of hydrogel contact lenses and the overall comfort of patients with tear deficiency. To allow for statistical analysis, a thin lens was fitted in one eye and a thicker lens of the same characteristics in the contralateral eye. Subjects were asked to wear the lenses for 30 days on a normal daily wear basis and to graduate several factors such as comfort, dryness sensation, redness, photophobia, tearing, quality of vision and others. The results indicate that thicker lenses were preferred in terms of comfort, dryness sensation, photophobia and handling whereas thinner lenses were considered to give a better quality of vision. As a whole, thicker lenses were better tolerated by the patient. Central thickness was found to be of significant relevance when choosing a contact lens, especially when the tear film is deficient.     

Non‐Arrhenius and non‐WLF kinetics in food systems

The classic Arrhenius and WLF equations are commonly used to describe rate–temperature relations in food and biological systems. However, they are not unique models and, because of their mathematical structure, give equal weight to rate deviations at the low‐ and high‐temperature regions. This makes them particularly useful for systems where what happens at low temperatures is of interest, as in spoilage of foods during storage, or where the effect is indeed exponential over a large temperature range, as in the case of viscosity. There are systems, however, whose activity is only noticeable above a certain temperature level. A notable example is microbial inactivation, for which these two classical models must be inadequate simply because cells and spores are not destroyed at ambient temperature. For such systems a model that identifies the temperature level at which the rate becomes significant is required. Such an alternative model is Y = ln{1 + exp[c(T ? T _c)]} ^m, where Y is the rate parameter in question (eg a reaction rate constant), T_c is the marker of the temperature range where the changes accelerate, and c and m are constants. (When m = 1, Y at T ? T_c is linear. When m ≠ 1, m is a measure of the curvature of Y at T ? T_c.) This model has at least a comparable fit to published rate–temperature relationships of browning and microbial inactivation as well as viscosity–temperature data previously described by the Arrhenius or WLF equation. This alternative log logistic model is not based on the assumption that there is a universal analogy between totally unrelated systems and simple chemical reactions, which is explicitly assumed when the Arrhenius equation is used, and it has no special reference temperature, as in the WLF equation, whose physical significance is not always clear. It is solely based on the actual behaviour of the examined system and not on any preconceived kinetics. © 2002 Society of Chemical Industry