Search results for "Freezing"
showing 10 items of 96 documents
Putrescine accumulation in Arabidopsis thaliana transgenic lines enhances tolerance to dehydration and freezing stress
2011
Polyamines have been globally associated to plant responses to abiotic stress. Particularly, putrescine has been related to a better response to cold and dehydration stresses. It is known that this polyamine is involved in cold tolerance, since Arabidopsis thaliana plants mutated in the key enzyme responsible for putrescine synthesis (arginine decarboxilase, ADC; EC 4.1.1.19) are more sensitive than the wild type to this stress. Although it is speculated that the over-expression of ADC genes may confer tolerance, this is hampered by pleiotropic effects arising from the constitutive expression of enzymes from the polyamine metabolism. Here, we present our work using A. thaliana transgenic pl…
Skull Bone Defects Reconstruction with Custom-Made Titanium Graft shaped with Electron Beam Melting Technology: Preliminary Experience in a Series of…
2017
Background: Cranioplasty represents a challenge in neurosurgery. Its goal is not only plastic reconstruction of the skull but also to restore and preserve cranial function, to improve cerebral hemodynamics, and to provide mechanical protection of the neural structures. The ideal material for the reconstructive procedures and the surgical timing are still controversial. Many alloplastic materials are available for performing cranioplasty and among these, titanium still represents a widely proven and accepted choice. Methods: The aim of our study was to present our preliminary experience with a “custom-made” cranioplasty, using electron beam melting (EBM) technology, in a series of ten patien…
Evaluation of Microbiological and Physico-Chemical Quality of Raw Milk from Sibiu Dairy Farm Province of Romania
2011
Research aims at benchmarking the quality of raw milk supplied by four private farms in the county of Sibiu at a distance of about 25 km each for a period of three months (April, May, June 2010). Samples were subject to particularly microbiological measurements (total number of germ and somatic cells), physico-chemical (acidity, fat density, non-fat dry matter, protein and freezing point titre) by international standard methods. The results of the four farms show different variations of the parameters analyzed as follows: 55.5% of the samples fall in physico-chemical parameters of standard quality and 79% of the samples fall within the parameters of microbiological quality standard and with…
In Vitro Bioavailability of Phenolic Compounds from Five Cultivars of Frozen Sweet Cherries (Prunus aviumL.)
2008
The bioavailability of phenolic compounds from five cultivars of frozen sweet cherries was assessed by a digestion process involving pepsin-HCl digestion (to simulate gastric digestion) and pancreatin digestion with bile salts (to simulate small intestine conditions) and dialyzed to assess serum- and colon-available fractions. After pepsin digestion, the % recovery of total phenolics, relative to the original starting material, increased, whereas the % anthocyanins did not change. Following pancreatic digestion and dialysis, the total phenolics in the IN (serum-available) fraction was about 26–30% and the OUT (colon-available) fraction was about 77–101%. The anthocyanin content in the IN fr…
A laboratory study on the uptake of HCl, HNO3, and SO2 gas by ice crystals and the effect of these gases on the evaporation rate of the crystals
1998
The results of our new and earlier laboratory studies on the uptake of gases by ice crystals are summarized in terms of (1) the equilibrium phase diagram for a system gas/H2O, (2) the effect of these gases on the evaporation rate of ice crystals, and (3) in terms of the uptake of the gases by water drops. It is shown that the intrinsic quasi-liquid layer significantly affects the uptake of a gas by an ice surface in that, depending on the gas phase concentration, the layer thickness may be considerably increased by depressing the equilibrium freezing point causing additional surface melting. It is further shown that the evaporation rate of ice particles previously exposed to a gas may becom…
Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 cell surface hydrophobicity and survival of the cells under adverse environmental condi…
2012
Abstract Changes in the cell surface hydrophobicity (CSH) of probiotic bacteria Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 and the survival of these cells were examined in response to varied cultivation conditions and adverse environmental conditions. An inverse linear relationship (P < 0.01) was detected between the CSH of intact L. acidophilus La5 and B. lactis Bb12 and survival of cells subjected to subsequent freezing/thawing, long-term storage or exposure to mineral and bile acids. The observed relationships were supported by significant correlations between the CSH and changes in composition of the cell envelopes (proteins, lipids and carbohydrates) of L. aci…
Membrane fatty acid composition and fluidity are involved in the resistance to freezing of Lactobacillus buchneri R1102 and Bifidobacterium longum R0…
2015
International audience; Determinations of membrane fatty acid composition and fluidity were used together with acidification activity and viability measurements to characterize the physiological state after freezing of Lactobacillus buchneri R1102 and Bifidobacterium longum R0175 cells harvested in the exponential and stationary growth phases. For both strains, lower membrane fluidity was achieved in cells harvested in the stationary growth phase. This change was linked to a lower unsaturated-to-saturated fatty acid ratio for both strains and a higher cyclic-to-saturated fatty acid ratio for L. buchneri R1102 alone. These membrane properties were linked to survival and to maintenance of aci…
Experimental investigations on a model of cryogenic edema.
1987
The role of mechanisms underlying formation and progression of vasogenic brain edema is investigated. On this purpose, cerebral edema was produced by cortical freezing in two different brain situations in rabbits (with or without replacement of bone flap). BBB (Blood-Brain Barrier) breakdown was evaluated by observation of Evans blue extravation, while a histopathological evaluation was carried out by light and transmission electron microscopy. Water content of brain tissue was determined by the wet/dry weight ratio method. Comparison of extension and intensity of cerebral edema between these two groups of animals shows a statistically significant difference: there was evidence of higher wa…
Cryopreservation of Escherichia coli K12TG1: Protection from the damaging effects of supercooling by freezing
2015
Injuries in living cells caused by water freezing during a freeze-thaw process have been extensively reported. In particular, intracellular water freezing has long been incriminated in cell death caused by a high cooling rate, but this supposition could not always be demonstrated. This work aims to discriminate the role of water freezing, dehydration and cold-induced injuries in cellular damage occuring during cryopreservation. For this purpose, Escherichia coli K12TG1 suspensions were maintained in a supercooled or frozen state at -20°C for times ranging from 10 min to 5 h. The supercooled state was maintained for a long period at -20°C by applying a non-injurious isostatic pressure (P<40 …
Damage in Escherichia coli Cells Treated with a Combination of High Hydrostatic Pressure and Subzero Temperature
2007
ABSTRACT The relationship between membrane permeability, changes in ultrastructure, and inactivation in Escherichia coli strain K-12TG1 cells subjected to high hydrostatic pressure treatment at room and subzero temperatures was studied. Propidium iodide staining performed before and after pressure treatment made it possible to distinguish between reversible and irreversible pressure-mediated cell membrane permeabilization. Changes in cell ultrastructure were studied using transmission electron microscopy (TEM), which showed noticeable condensation of nucleoids and aggregation of cytosolic proteins in cells fixed after decompression. A novel technique used to mix fixation reagents with the c…