Prehydration and the Reversibility of Solid-State Hydrogen-Deuterium Exchange.

The reversibility of solid-state hydrogen-deuterium exchange (ssHDX) and the effects of prehydration on the rate and extent of deuterium incorporation were evaluated using poly-d,l-alanine (PDLA) peptides colyophilized with various excipients. In prehydration studies, samples were equilibrated at a controlled relative humidity (6% or 11% RH) for 12 h and then transferred to corresponding D2O humidity conditions (6% or 11% RD) for deuterium labeling. In amorphous samples, the rate and extent of deuterium incorporation were similar in prehydrated samples and controls not subjected to prehydration. In reversibility studies, PDLA samples were maximally deuterated in controlled D2O humidity conditions (6% or 11% RD) and then transferred to corresponding H2O relative humidity (0%, 6%, 11%, or 43% RH). Hysteresis in deuterium removal was observed when compared with the deuterium incorporation kinetics for all formulations and conditions, confirming that the reaction is reversible in the solid state and that the forward and reverse processes differ. The extent of deuterium loss reached a plateau that depended on the delabeling relative humidity. Reverse reaction rate constants were quantified using a first-order kinetic model, a limiting case of the reversible first-order model applicable under sink conditions. For other conditions, plateau (steady-state) deuteration levels were related to forward and reverse rate constants in a reversible first-order kinetic model. The results support a mechanistic interpretation of ssHDX kinetics as a reversible first-order process, in which the forward (deuteration) rate depends on the activity of the deuterium donor.

Moss antheridia are desiccation tolerant: Rehydration dynamics influence sperm release in Bryum argenteum.

PREMISE OF THE STUDY: Free-living sperm of mosses are known to be partially desiccation tolerant. We hypothesized that mature moss antheridia should also tolerate desiccation and that rehydration to partial turgor (prehydration) or rehydration to full turgor (rehydration) before immersion in water is required for full recovery from any damaging effects of prior desiccation. METHODS: Bryum argenteum (silvery-thread moss) was grown in continuous culture for several months, produced mature perigonia (clusters of antheridia), and these were subjected to a slow rate of drying (∼36 h from full turgor to desiccation) and equilibration with 50% relative humidity. Perigonia were prehydrated (exposed to a saturated atmosphere) or rehydrated (planted upright in saturated media) for 0, 45, 90, 135, 180, and 1440 min, then immersed in sterile water. Time to first sperm mass release, number of antheridia releasing sperm masses, and the integrity of the first sperm mass released were assessed. KEY RESULTS: Rehydration of dried antheridia for at least 3 h before immersion in water resulted in antheridia functioning similar to control undried antheridia. Compared with rehydration, prehydration was not effective in the recovery of antheridia from desiccation. CONCLUSIONS: For the first time, moss antheridia are shown to be fully desiccation tolerant at a functional level, capable of releasing fully functional sperm following a slow drying event provided the antheridia are allowed to rehydrate at least 3 h before immersion in water.

Selecting a strategy for prevention of contrast-induced nephropathy in clinical practice: an evaluation of different clinical practice guidelines using the AGREE tool.

BACKGROUND: Contrast-induced acute kidney injury (CI-AKI) is a potential complication of radio-contrast investigations. Many organisations have published guidance documents on the prevention of CI-AKI. Our aim is to explore the scope, content, consistency, practicality in clinical practice and reasons for eventual underlying discrepancies of these documents. METHODS: We searched the literature for guidance documents developed to guide prevention of CI-AKI up to 09/2014. Four reviewers appraised guideline quality using the 23-item AGREE-II instrument, which rates reporting of the guidance development process across six domains: scope and purpose, stakeholder involvement, rigour of development, clarity of presentation, applicability and editorial independence. Total scores were calculated as standardised averages by domain. RESULTS: Twenty-four guidance documents were evaluated. The guidance documents were produced by radiologists (N = 7), intensivists (N = 2), nephrologists (N = 6) or multidisciplinary teams (N = 9). One document did not mention the background of the authors. Only guidance documents (N = 15) that were not mere adaptations of existing guidelines were evaluated more in depth, using the AGREE tool. Overall, quality was mixed: only one clinical practice guidance document obtained an average score of >50% for all domains. The evidence was rated in a systematic way in only 11, and only 7 graded the strength of the recommendations. The Kidney Diseases Improving Global Outcomes guideline was the only one recommended without adaptions by all assessors. The guidance documents agreed in recommending pre-hydration as the main preventive measure, but there was difference in recommended total volumes, composition, rate and duration of the infused solutions. There was no consensus on the use of NaHCO3, with eight recommending it, six considering it and one not. Five guidance documents mentioned oral pre-hydration as a possibility, and none recommended N-acetylcysteine as solitary preventive measure. More recent guidance documents recommend avoiding hypertonic contrast media, but did not recommend preference of iso-osmolar over low-osmolar contrast media. Most guidance documents recognised pre-existing chronic kidney disease, diabetes, age and cardiovascular comorbidity as risk factors. CONCLUSIONS: There seems to be a relative consensus on the need for adequate pre-hydration to avoid CI-AKI, but recommendations to define at-risk populations for whom these measures should be applied and how they should be implemented differ substantially. Based on accumulating evidence, more recent guidelines do not recommend iso-osmolar over low-osmolar contrast media, whereas all recommend avoiding hypertonic agents.

Hydraulic conductivity of geosynthetic clay liners to trona ash leachate: Effects of mass per unit area, bundles of fiber existence, and preydration conditions.

The barrier performance of geosynthetic clay liners (GCLs) to coal combustion products (CCPs) is of primary importance. One of the CCPs leachates that has a damaging effect on hydraulic conductivity is trona ash leachate (TAL). In this study, the hydraulic conductivity of sodium GCL (Na-GCL) to TAL was investigated in terms of mass per unit area (MPUA). The hydraulic conductivity of GCLs to TAL was 2.6 × 10-6 and 7.6 × 10-7 m/s when the MPUA was 3.0 kg/m2 (Mb3) and 4.0 kg/m2 (Mb4), respectively. Dye tests conducted on these GCLs showed that flow preferentially occurred through bundles of fibers existing in the GCLs. In contrast, increasing the MPUA to 5.0 kg/m2 (Mb5) led to a decrease in the hydraulic conductivity (i.e. 4.1 × 10-11 m/s). Additional tests were performed on fiber-free GCLs to determine the role of fiber bundles. Regardless of MPUA, the fiber-free GCLs had low hydraulic conductivity (6.7 × 10-11 m/s). Prehydrating Mb3 and Mb4 with deionized water (DIW) before permeation with TAL also decreased the hydraulic conductivity. The hydraulic conductivities of prehydrated Mb3 and Mb4 were 1.6 × 10-10 and 4.8 × 10-11, respectively. Chemical analyses showed that the cation exchange reaction had a negligible influence on the hydraulic conductivity. Because TAL was a potential source of Na+ throughout the tests.

Microstructural studies of imitation cheese with a shift in continuous phase.

When casein is replaced with starch in imitation cheese, the functionality changes. Three different microscopy methods were applied to understand the microstructural differences in the product depending on which component dominates the microstructure. Confocal Laser Scanning Microscopy (CLSM) for component identification. Scanning Electron Microscopy (SEM) and Cryogenic Scanning Electron Microscopy (Cryo-SEM) for studying surface structures. Differences in the surface structures were detected between SEM and Cryo-SEM. In SEM, starch appeared rough and protein smooth, while in Cryo-SEM no starch roughness of the surface was found. A change in starch modification and effects of protein prehydration was also analysed. Adding octenyl succinic anhydride (OSA) modified starch for emulsifying properties resulted in a microstructure with fragmented protein at a protein level of 7 %, but not at 9 or 12 %. Protein prehydration had limited effect on microstructure. On a macrostructural level, the change to an emulsifying starch increased hardness in imitation cheese with 7 and 9 % protein. Protein prehydration slightly decreased the hardness, but the difference was not significant at all concentrations. This research provides valuable information about the microstructure of imitation cheese at a 50/50 composition, how the microstructure changes with an emulsifying starch and what occurs after a protein prehydration was included in the production.

Impact of pre-hydration duration on high-dose methotrexate induced nephrotoxicity in childhood acute lymphoblastic leukaemia in resource constraint centers: a randomized crossover study.

PURPOSE: Hydration before starting high-dose methotrexate (HD-MTX) ensures good renal perfusion and alkaline urinary pH. The duration of pre-hydration is not uniform across protocols. We compared 6-h versus 12-h of pre-hydration for HD-MTX therapy in childhood acute lymphoblastic leukaemia (ALL) at our centre where serial MTX level monitoring is not feasible. METHODS: This randomised cross-over study consecutively enrolled children < 12 years with ALL receiving HD-MTX. Children with pre-existing renal disease or those exposed to nephrotoxic drugs were excluded. Two groups receiving 6-h versus 12-h pre-hydration on alternate basis in same patient (each exposed to four cycles of 2-5 g/m2 of HD-MTX) were compared for HD-MTX induced nephrotoxicity (primary outcome) and other HD-MTX toxicities (HMT) as per common terminology criteria for adverse events (CTCAE-4.0). HD-MTX was administered over 24 h as per BFM-protocol-2009. Solitary MTX levels at 36-h (MTX36) were outsourced and leucovorin (LV) was started at 36 h at 15 mg/m2/dose for 6-8 doses 6-hourly depending on MTX36. Hydration fluid was dextrose normal saline with sodium-bicarbonate and administered till last LV dose. RESULTS: Total 136 HD-MTX cycles in 34 patients (age range 5-144 months) were evaluated. Nephrotoxicity [2/68 (2.9%) in 6-h versus 1/68 (1.5%) in 12-h] and HMT incidence was comparable in two pre-hydration groups. Median MTX36 levels were not affected by duration of hydration irrespective of administered dose of HD-MTX. Median serum creatinine at baseline, post-pre-hydration and at 36-h post start of HD-MTX were comparable. CONCLUSION: Reduction of pre-hydration duration does not affect HD-MTX induced nephrotoxicity and MTX36 levels in children < 12 years.

Device Based Approaches to the Prevention of Contrast-Induced Acute Kidney Injury.

Contrast-induced acute kidney injury is not uncommon after percutaneous coronary intervention, particularly in high-risk patients. Pharmacologic approaches have not demonstrated significant benefit, and numerous device-based approaches exist targeting a variety of pathways. In this review, we summarize the most recent interventions and the evidence behind them.

Pre-hydration in cisplatin-based CCRT: Effects on tumour concentrations and treatment outcome.

AIMS: Pre-hydration is routinely applied to reduce nephrotoxicity in concurrent cisplatin-based chemo-radiotherapy (CCRT). However, pre-hydration may also have systemic effects, potentially leading to lower tumour cisplatin concentrations. We investigated the impact of pre-hydration on tumour cisplatin concentrations in mice, and on treatment outcomes in a clinical cohort study. MATERIALS AND METHODS: Four groups of 20 mice received either no pre-hydration prior to full-dose (6 mg/kg) or half-dose cisplatin, overnight dehydration prior to full-dose cisplatin (dehydration), or NaCl intraperitoneally prior to full-dose cisplatin (pre-hydration). Kidney function and tumour platinum concentration were measured. In patients, a retrospective study compared 2 historical NSCLC cohorts which received CCRT with daily cisplatin, with and without standard pre-hydration. Overall survival (OS) and progression free survival (PFS) were compared using Kaplan-Meier and cox-regression. RESULTS: Pre-hydration significantly decreased cisplatin tumour concentrations in mice, comparable to mice receiving half the dose. In 419 patients (211 without and 208 with pre-hydration) with median follow-up 22 months, there were no significant differences in PFS (18 vs. 15 months) or OS (23 vs. 23 months). CONCLUSION: Pre-hydration reduces cisplatin tumour concentrations in mice, but it does not compromise treatment outcomes in NSCLC patients treated with daily cisplatin and radiotherapy.

Hydration with 15 mEq Magnesium Is Effective at Reducingthe Risk for Cisplatin-induced Nephrotoxicity in Patients Receiving Cisplatin (≥50 mg/m2) Combination Chemotherapy.

AIM: We aimed to assess whether the efficacy of pre-hydration with 15 mEq magnesium prevents cisplatin-induced nephrotoxicity in cisplatin regimens (dosage: 50 mg/m(2)or more) for gynecological cancer. PATIENTS AND METHODS: This historical, prospective cohort study compared nephrotoxicity in patients who received pre-hydration with or without magnesium sulfate (Mg-hydration group, n=37; non-Mg-hydration group, n=37). We used serum creatinine (Scr), creatinine clearance (Ccr) and Risk, Injury, Failure, Loss of kidney function and End-stage kidney disease (RIFLE) criteria. RESULTS: A change of Scr and Ccr in the Mg-hydration group was higher than in the non-Mg-hydration group. Based on the RIFLE criteria, the number of moderate renal dysfunction patients classified as "Risk" in the Mg-hydration group was significantly lower than in the non-Mg-hydration group (Mg-hydration group=21.6%; non-Mg-hydration group=51.4%; p<0.01). Serum magnesium levels in the Mg-hydration group significantly declined during chemotherapy (p<0.01). CONCLUSION: We found that a 15 mEq magnesium as pre-hydration provided nephroprotective effects in patients receiving this cisplatin regimen. Future research should involve finding appropriate magnesium doses.

Deceleration processes of secondary electrons produced by a high-energy Auger electron in a biological context.

PURPOSE: To simulate the deceleration processes of secondary electrons produced by a high-energy Auger electron in water, and particularly to focus on the spatial and temporal distributions of the secondary electron and the collision events (e.g. ionization, electronic excitation, and dissociative electron attachment) that are involved in the multiplication of lesions at sites of DNA damage. MATERIALS AND METHODS: We developed a dynamic Monte Carlo code that considers the Coulombic force between an ejected electron and its parent cation produced by the Auger electron in water. Thus our code can simulate some return electrons to the parent cations. Using the code, we calculated to within the order of femtoseconds the temporal evolution of collision events, the mean energy, and the mean traveling distance (including its spatial probability distribution) of the electron at an ejected energy of 20 eV. RESULTS: Some of the decelerating electrons in water in the Coulombic field were attracted to the ionized atoms (cations) by the Coulombic force within hundreds of femtoseconds, although the force did not significantly enhance the number of ionization, electronic excitation, and dissociative electron attachment collision events leading to water radiolysis. CONCLUSIONS: The secondary electrons are decelerated in water by the Coulombic force and recombined to the ionized atoms (cations). Furthermore, the some return electrons might be prehydrated in water layer near the parent cation in DNA if the electrons might be emitted from the DNA. The prehydrated electron originated from the return electron might play a significant role in inducing DNA damage.

Impact of Wheat Bran Hydration Properties As Affected by Toasting and Degree of Milling on Optimal Dough Development in Bread Making.

The impact of the hydration capacity and hydration rate of wheat bran on optimal bread dough development and loaf volume was investigated using coarse bran, both native as well as after toasting, milling, presoaking, and combinations of the latter. It was found that toasting reduces bran's hydration rate, which, during mixing, results in a temporary excess of water in which dough development takes place inefficiently and hence requires additional time. This mechanism was further substantiated by the observation that delayed dough development can be counteracted by the presoaking of bran. Milling of bran increases its hydration rate and results in faster optimal dough development. Presoaking of nonmilled bran, however, did not result in faster dough development. Smaller bran particles do lead to faster dough development, probably due to increased proper contacts between flour particles. Optimal loaf volumes did not change upon milling and toasting.

The impact of prehydration on the clearance and toxicity of high-dose methotrexate for pediatric patients.

Abstract High-dose methotrexate (HD-MTX) is an important chemotherapy for various pediatric malignancies. However, in contrast to precise recommendations on supportive care following the start of HD-MTX infusion, studies on the hydration regimen prior to HD-MTX infusion are lacking, and the local standard differs between pediatric oncology centers. Therefore, we prospectively evaluated the relevance of two common prehydration regimens on the clearance and toxicity of MTX in a randomized crossover study. There was no impact of the prehydration regimen on plasma levels and toxicity of MTX, but most parents preferred a fast prehydration regimen due to a significantly shorter inpatient treatment (mean duration 3.39 ± 0.79 days vs. 4.36 ± 0.70 days, p < 0.001). Based on our results, short prehydration seems safe, and may be recommended prior to the start of HD-MTX infusions instead of initiating hydration the preceding day.

Particle size changes in unsealed mineral trioxide aggregate powder.

INTRODUCTION: Mineral trioxide aggregate (MTA) is commonly supplied in 1-g packages of powder that are used by some clinicians across several treatments against the manufacturer's instructions. ProRoot MTA cannot be resealed after opening, whereas MTA Angelus has a resealable lid. This study assessed changes in particle size distribution once the packaging had been opened. METHODS: Fresh ProRoot MTA and MTA Angelus powder were analyzed by using laser diffraction and scanning electron microscopy and compared with powder from packages that had been opened once and kept in storage for 2 years. The ProRoot packet was folded over, whereas the MTA Angelus jar had the lid twisted back to its original position. RESULTS: After 2 years, ProRoot MTA powder showed a 6-fold increase in particle size (lower 10% from 1.13 to 4.37 µm, median particle size from 1.99 to 12.87 µm, and upper 10% from 4.30 to 34.67 µm), with an accompanying 50-fold change in particle surface area. MTA Angelus showed only a 2-fold increase in particle size (4.15 to 8.32 µm, 12.72 to 23.79 µm, and 42.66 to 47.91 µm, respectively) and a 2-fold change in particle size surface area. CONCLUSIONS: MTA reacts with atmospheric moisture, causing an increase in particle size that may adversely affect the properties and shelf life of the material. Smaller particles have a greater predisposition to absorb moisture. Single-use systems are advised.

The Effect of Prehydration on Sensory Block Level in the Isobaric Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Even though the effect of prehydration on the spinal anesthesia-induced hypotension has not yet been concluded, prehydration prior to spinal anesthesia is recommended in order to reduce the incidence and severity of hypotension. We investigated the effects of prehydration on hemodynamic change during spinal anesthesia with isobaric 0.5% tetracaine. METHODS: We prospectively performed this study on 96 patients who underwent elective transurethral surgery from October 2002 to January 2004. Patients were randomly allocated to receive either no prehydration or 10 ml/kg crystalloids administered over 10 15 min prior to spinal anesthesia. We compared dermatomal spreads of spinal anesthesia, hemodynamic parameters (blood pressure, heart rate), incidences of hypotension and bradycardia between two groups. RESULTS: Hemodynamic parameters, incidences of hypotension and bradycardia showed no statistically significant differences during spinal anesthesia between two groups. There were statistically significant differences in the dermatomal spread of sensory levels between two groups from 5 to 90 min after spinal anesthesia. Sensory block levels in prehydration group were statistically lower than no prehydration group. CONCLUSION: We hypothesized that prehydration can be one of factors that influence on dermatomal spread of local anesthetics in isobaric spinal anesthesia. The difference of dermatomal spread between two groups may be caused by brain blood barrier (BBB)-freely passing crystalloids, which may influence on the volume and density of cerebrospinal fluids. To verify this phenomenon found in our study, further investigation is still warranted.

Prevention of Hypotension with Crystalloid Versus Colloid During Spinal or Combined Spinal-Epidural Anesthesia for Cesarean Delivery / 대한마취과학회지

BACKGROUND: The prevention of hypotension continues to be one of major challenges in spinal anesthesia (SA) for cesarean delivery. And prehydration is widely performed to prevent hypotension. However, some controversy exists over the types of fluid used for prehydration. Therefore, we investigated the effects of crystalloid versus colloid preload on the incidences of hypotension, and the notion that minimal local anesthetic used in combined spinal-epidural anesthesia (CSEA) could further decrease the incidence of hypotension after colloid preloading. METHODS: One hundred and fifty parturients were randomly allocated into three groups: CR (crystalloid)-SA, CO (colloid)-SA, and CO-CSEA according to the types of preload and anesthesia. In the CR-SA group, 1,000-1,500 ml of crystalloid was administered under spinal anesthesia. In the CO-SA and CO-CSEA groups, 500 ml of colloid followed by 500-1,000 ml of crystalloid under SA and CSEA was administered, respectively. Bupivacaine 9 mg with opioids was used for SA, and bupivacaine 6 mg with opioids and epidural top-up with 0.25% bupivacaine 10 ml for CSEA. Incidences of hypotension, nausea and vomiting were recorded until delivery. RESULTS: Colloid preload reduced the incidence of hypotension (18% vs 44%, P = 0.005), and side effects (2% vs 20%, P = 0.005) compared to crystalloid in SA. However, lowering local anesthetic using CSEA (hypotension 20%, side effects 4%) did not further decrease the incidences of hypotension and side effects when using colloid. CONCLUSIONS: Colloid is a better fluid for prehydration in cesarean section under spinal anesthesia. 18-20% is considered a minimum incidence of hypotension.