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Pressure Stability (pressure + stability)
Selected AbstractsEFFECT OF HIGH PRESSURE TREATMENT ON CYTOPLASMIC 5,-NUCLEOTIDASE FROM RABBIT SKELETAL MUSCLEJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2007SUNAO MORI ABSTRACT We investigated the effect of high-pressure treatment on the properties of cytoplasmic 5, -nucleotidase (NT), which converts inosine monophosphate (IMP) into inosine. After pressure treatment at 400 MPa, the activity of purified IMP-NT remained at almost 100%, but the activity of partially purified adenosine monophosphate (AMP)-NT decreased to about 40%. These data suggest that there is a difference in the pressure stability between the enzymes. In situ fluorescence spectroscopy of IMP-NT under pressure showed that its pressure-induced denaturation was reversible. When the pressure was reduced from the highest pressure to ambient pressure, hysteresis was observed. This suggests that high pressure treatment may lead to a partial change in the affinity of the subunits for each other once they have dissociated. The activities of IMP-NT and AMP-NT extracted from pressure-treated muscles decreased remarkably between 250 and 450 MPa, but IMP-NT was more stable than AMP-NT. [source] Monolithic poly(glycidyl methacrylate- co -divinylbenzene) capillary columns functionalized to strong anion exchangers for nucleotide and oligonucleotide separationJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2006Wolfgang Wieder Abstract In the present work, poly(glycidyl methacrylate- co -divinylbenzene) monoliths were synthesized and further derivatized to obtain strong anion exchange supports. Capillary monoliths (65×0.2 mm id) were prepared in situ by copolymerization of glycidyl methacrylate and divinylbenzene, employing 1-decanol and tetrahydrofuran as porogens. The free epoxy groups were derivatized in a two step synthesis to obtain quaternary ammonium functionalities. On testing the pressure stability of the synthesized monolith, a highly linear dependence between flow rate and pressure drop was obtained, indicating the high stability of the material even at high flow rates. The morphology of the copolymer was investigated by scanning electron microscopy. Mercury intrusion porosimetry showed a narrow pore size distribution, having a maximum at 439 nm. On recording a van Deemter plot the number of theoretical plates per meter was found to be 59 324. The produced strong anion exchange monoliths turned out to be highly suitable for the separation of nucleotides and oligonucleotides. [source] Temperature,pressure stability of green fluorescent protein: A Fourier transform infrared spectroscopy studyBIOPOLYMERS, Issue 4 2002Carsten H. Scheyhing Abstract Green fluorescent protein (GFP) is widely used as a marker in molecular and cell biology. For its use in high-pressure microbiology experiments, its fluorescence under pressure was recently investigated. Changes in fluorescence with pressure were found. To find out whether these are related to structural changes, we investigated the pressure stability of wild-type GFP (wtGFP) and three of its red shift mutants (AFP, GFPmut1, and GFPmut2) using Fourier transform infrared spectroscopy. For the wt GFP, GFPmut1, and GFPmut2 we found that up to 13,14 kbar the secondary structure remains intact, whereas AFP starts unfolding around 10 kbar. The 3-D structure is held responsible for this high-pressure stability. Previously observed changes in fluorescence at low pressure are rationalized in terms of the pressure-induced elastic effect. Above 6 kbar, loss of fluorescence is due to aggregation. Revisiting the temperature stability of GFP, we found that an intermediate state is populated along the unfolding pathway of wtGFP. At higher temperatures, the unfolding resulted in the formation of aggregates of wtGFP and its mutants. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 244,253, 2002 [source] Investigating the potential of Bacillus subtilis ,-amylase as a pressure-temperature-time indicator for high hydrostatic pressure pasteurization processesBIOTECHNOLOGY PROGRESS, Issue 4 2009Tara Grauwet Abstract The potential of Bacillus subtilis ,-amylase (BSA) as a pressure-temperature-time indicator (pTTI) for high pressure pasteurization processing (400,600 MPa; Ti 10,40°C; 1,15 min) was investigated. A stepwise approach was followed for the development of an enzyme-based, extrinsic, isolated pTTI. First, based on literature data on the pressure stability, BSA was selected as a candidate indicator. Next to the accuracy and ease of the measurement of the indicator's response (residual activity) to the pressure treatment, the storage and handling stability of BSA at atmospheric pressure was verified. Second, the stability of BSA at a constant temperature (T) and time in function of pressure (p) was investigated. Solvent engineering was used to shift the inactivation window of BSA in the processing range of interest. Third, the enzyme (1 g/L BSA,MES 0.05 M pH 5.0) was kinetically calibrated under isobaric-isothermal conditions. Time dependent changes in activity could be modeled best by a first-order model. Except for low pressures and high temperatures, a synergistic effect between pressure and temperature could be observed. Based on the model selected to describe the combined p,T-dependency of the inactivation rate constant, an elliptically shaped isorate contour plot could be constructed, illustrating the processing range where BSA can be used to demonstrate temperature gradients. Fourth, the validity of the kinetic model was tested successfully under dynamic conditions similar to those used in food industry. Finally, the indicator was found suitable to demonstrate nonuniformity in two-sectional planes of a vertical, single vessel system. © 2009 American Institute of Chemical Engineers. Biotechnol. Prog., 2009 [source] Primary endoluminal stenting of transplant renal artery stenosis from cadaver and non-heart-beating donor kidneysCLINICAL TRANSPLANTATION, Issue 3 2006D. Ridgway Abstract:, This study evaluated the efficacy of primary endovascular stenting in cases of transplant renal artery stenosis (TRAS) from cadaver and non-heart-beating donor kidneys. Patients with TRAS (n = 13) from a single-centre transplant population (n = 476) were treated by primary percutaneous angioplasty and endovascular stenting. The short-term efficacy of this intervention is demonstrated in terms of serum creatinine, glomerular filtration rate (GFR) biochemical, anti-hypertensive medications and mean arterial blood pressure control. Stenting for TRAS was performed in male (n = 10) and female (n = 3) recipients. The median age at transplantation was 55 yr (range 10,67 yr). Stenting occurred at a median duration of 410 d post-transplantation (range 84,5799 d). Mean serum creatinine (pre, 247 ,mol/L; post, 214 ,mol/L; p = 0.002), GFR (pre, 82.6 mL/min; post, 100.9 mL/min; p<0.001), arterial blood pressure (pre, 104 mmHg; post, 97 mmHg; p = 0.036) and the number of anti-hypertensive medications required (pre, 3.4; post, 3.0; p = 0.002) showed significant improvement after post-endovascular therapy. There were no serious complications encountered. Primary endovascular stenting of TRAS produces a significant improvement in biochemical parameters of renal graft function and in blood pressure stability, with the benefit of low patient morbidity and single arterial puncture. Primary endoluminal stenting of TRAS is a safe and effective procedure for the treatment of TRAS. [source] | ||||||||||