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58 result(s) for "Mannitol - standards"
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Standardising the Lactulose Mannitol Test of Gut Permeability to Minimise Error and Promote Comparability
Lactulose mannitol ratio tests are clinically useful for assessing disorders characterised by changes in gut permeability and for assessing mixing in the intestinal lumen. Variations between currently used test protocols preclude meaningful comparisons between studies. We determined the optimal sampling period and related this to intestinal residence. Half-hourly lactulose and mannitol urinary excretions were determined over 6 hours in 40 healthy female volunteers after administration of either 600 mg aspirin or placebo, in randomised order at weekly intervals. Gastric and small intestinal transit times were assessed by the SmartPill in 6 subjects from the same population. Half-hourly percentage recoveries of lactulose and mannitol were grouped on a basis of compartment transit time. The rate of increase or decrease of each sugar within each group was explored by simple linear regression to assess the optimal period of sampling. The between subject standard errors for each half-hourly lactulose and mannitol excretion were lowest, the correlation of the quantity of each sugar excreted with time was optimal and the difference between the two sugars in this temporal relationship maximal during the period from 2½-4 h after ingestion. Half-hourly lactulose excretions were generally increased after dosage with aspirin whilst those of mannitol were unchanged as was the temporal pattern and period of lowest between subject standard error for both sugars. The results indicate that between subject variation in the percentage excretion of the two sugars would be minimised and the differences in the temporal patterns of excretion would be maximised if the period of collection of urine used in clinical tests of small intestinal permeability were restricted to 2½-4 h post dosage. This period corresponds to a period when the column of digesta column containing the probes is passing from the small to the large intestine.
Montanide ® ISA 720 vaccines: quality control of emulsions, stability of formulated antigens, and comparative immunogenicity of vaccine formulations
Montanide ® ISA 720 is an experimental adjuvant, formulated as water-in-oil emulsions, that induces high antibody titers in several animal species. It has been used in human vaccine trials with malaria and HIV vaccines. The heightened response is likely due, in part, to the formation of a depot at the injection site. However, post-formulation modifications were seen with seven proteins tested during storage of ISA 720 formulations at 37 °C for 1 week and two proteins stored longer at 4 °C. Potency studies in mice, in which the stored vaccines were diluted into placebo emulsions for appropriate dosing, indicated that this instability could lead to loss of immunogenicity in the post-injection depot, limiting the allowable storage time of preformed vaccines. We describe point-of-injection formulation for ISA 720 vaccines that meets the requirement for in vitro stability. For preformed vaccines, addition of glycine or glycylglycine prevented antigen modification on storage at 37 °C, providing a potential way of stabilizing antigen/ISA 720 formulations for in vitro storage and the post-injection depot.
Improved Prediction of In Vivo Peroral Absorption from In Vitro Intestinal Permeability Using an Internal Standard to Control for Intra- and Inter-Rat Variability
To evaluate the use of an in vitro intestinal permeability model to predict rat and human absorption as well as to evaluate the use of an internal standard to control for intra- and inter-rat variability. In vivo peroral absorption and in vitro steady-state intestinal permeability coefficients were determined in the rat for a variety of structurally different compounds with different physicochemical properties including: progesterone, hydrocortisone, salicylic acid, caffeine, clonidine, p-aminoclonidine, UK-14304, oxymetazoline, mannitol, PEG 900, PEG 4000, and a number of novel hydrophilic chemical entities. The intestinal permeability coefficients determined in vitro could be used to predict the peroral absorption of a compound in both the rat and human. Normalizing the permeability of a test compound to an internal standard, e.g. mannitol, greatly improved the prediction of peroral absorption. The use of an internal standard can aid in the prediction of the peroral absorption of a test compound, in particular, for one that has moderate absorption in the range of 20-80%. Moreover, these methods would appear to be a useful means to improve the prediction of other absorption models as well, such as the Caco-2 cell systems and in-situ perfusion methods.
Optimal Monitoring of Weekly IGF-I Levels During Growth Hormone Therapy With Once-Weekly Somapacitan
Abstract Context Somapacitan is a long-acting growth hormone (GH) in development for once-weekly treatment of GH deficiency (GHD). Optimal monitoring of insulin-like growth factor-I (IGF-I) levels must account for weekly IGF-I fluctuations following somapacitan administration. Objective To develop and assess the reliability of linear models for predicting mean and peak IGF-I levels from samples taken on different days after dosing. Design A pharmacokinetic/pharmacodynamic model was used to simulate IGF-I data in adults and children following weekly somapacitan treatment of GHD. Setting and Patients 39 200 IGF-I profiles were simulated with reference to data from 26 adults and 23 children with GHD. Intervention(s) The simulated dose range was 0.02 to 0.12 mg/kg for adults and 0.02 to 0.16 mg/kg for children. Simulated data with >4 average standard deviation score were excluded. Main Outcome Measure(s) Linear models for predicting mean and peak IGF-I levels based on IGF-I samples from different days after somapacitan dose. Results Robust linear relationships were found between IGF-I sampled on any day after somapacitan dose and the weekly mean (R2 > 0.94) and peak (R2 > 0.84). Prediction uncertainties were generally low when predicting mean from samples taken on any day (residual standard deviation [RSD] ≤ 0.36) and peak from samples taken on day 1 to 4 (RSD ≤ 0.34). IGF-I monitoring on day 4 and day 2 after dose provided the most accurate estimate of IGF-I mean (RSD < 0.2) and peak (RSD < 0.1), respectively. Conclusions Linear models provided a simple and reliable tool to aid optimal monitoring of IGF-I by predicting mean and peak IGF-I levels based on an IGF-I sample following dosing of somapacitan. A short visual summary of our work is available (1).
Early Osmotherapy in Severe Traumatic Brain Injury: An International Multicenter Study
The optimal osmotic agent to treat intracranial hypertension in patients with severe traumatic brain injury (TBI) remains uncertain. We aimed to test whether the choice of mannitol or hypertonic saline (HTS) as early (first 96 h) osmotherapy in these patients might be associated with a difference in mortality. We retrospectively analyzed data from 2015 from 14 tertiary intensive care units (ICUs) in Australia, UK, and Europe treating severe TBI patients with intracranial pressure (ICP) monitoring and compared mortality in those who received mannitol only versus HTS only. We performed multi-variable analysis adjusting for site and illness severity (Injury Severity Score, extended IMPACT score, and mean ICP over the first 96 h) using Cox proportional hazards regression. We collected data on 262 patients and compared patients who received early osmotherapy with mannitol alone (n = 46) with those who received HTS alone (n = 46). Mannitol patients were older (median age, 49.2 (19.2) vs. 40.5 (16.8) years; p = 0.02), with higher Injury Severity Scores (42 (15.9) vs. 32.1 [11.3]; p = 0.001), and IMPACT-TBI predicted 6-month mortality (34.5% [23–46] vs. 25% [13–38]; p = 0.02), but had similar APACHE-II scores, and mean and maximum ICPs over the first 96 h. The unadjusted hazard ratio for in-hospital mortality in patients receiving only mannitol was 3.35 (95% confidence interval [CI], 1.60–7.03; p = 0.001). After adjustment for key mortality predictors, the hazard ratio for in-hospital mortality in patients receiving only mannitol was 2.64 (95% CI, 0.96–7.30; p = 0.06). The choice of early osmotherapy in severe TBI patients may affect survival, or simply reflect clinician beliefs about their different roles, and warrants controlled investigation.
Sequential changes in urine production, glomerular filtration rate, and electrolyte excretion after mannitol administration
Abstract Introduction Acute kidney injury (AKI) leading to severe uremia is associated with high morbidity and mortality. Mannitol is an osmotic diuretic, widely used in the management of AKI, both as a bolus injection and as a constant rate infusion (CRI). Objectives To determine the plasma concentration of mannitol after a bolus injection and CRI at the recommended dosages, and to assess the effect of mannitol on renal function variables including urine production, glomerular filtration rate (GFR), and solute excretion. Methods Prospective cross-over design study, using 6 healthy dogs. Each dog underwent 3 protocols with at least a 7-day washout period between protocols. The first protocol included bolus injection of mannitol, the second protocol included bolus injection followed by CRI of mannitol and the third protocol (control) included injection of 5% dextrose in water (D5W). Urine production, GFR, and fractional excretion (FE) of solutes were measured for 10 hours. Results For all protocols, urine production significantly (P < .001) increased after bolus injection, but no significant difference in urine production or GFR was observed among the treatment groups. Mannitol injection increased the FE of sodium and urea nitrogen, but these effects were short-lived. Conclusions Mannitol has minimal effect on urine production and GFR but does increase FE of urea nitrogen and sodium, immediately after bolus injection. Constant rate infusion at a conventional dosage of 1 mg/kg/min cannot maintain these effects in dogs with normal renal function, because mannitol concentration decreases rapidly.
Evaluation of Myocardial Protection in Prolonged Aortic Cross-Clamp Times: Del Nido and HTK Cardioplegia in Adult Cardiac Surgery
Background and Objectives: Effective myocardial protection is essential for successful cardiac surgery outcomes, especially in complex and prolonged procedures. To this end, Del Nido (DN) and histidine-tryptophan-ketoglutarate (HTK) cardioplegia solutions are widely used; however, their comparative efficacy in adult surgeries with prolonged aortic cross-clamp (ACC) times remains unclear. This study aimed to compare the efficacy and safety of DN and HTK for myocardial protection during prolonged ACC times in adult cardiac surgery and to define clinically relevant thresholds. Materials and Methods: This retrospective study included a total of 320 adult patients who underwent cardiac surgery under cardiopulmonary bypass (CPB) with an aortic cross-clamp time ≥ 90 min. Data were collected from the medical records of elective adult cardiac surgery cases performed at a single center between 2019 and 2025. Patients were categorized into two groups based on the type of cardioplegia received: Del Nido (n = 160) and HTK (n = 160). The groups were compared using 1:1 propensity score matching. Clinical and biochemical outcomes—including troponin I (TnI), CK-MB, lactate levels, incidence of low cardiac output syndrome (LCOS), and need for mechanical circulatory support—were analyzed between the two cardioplegia groups. Subgroup analyses were performed according to ACC duration (90–120, 120–150, 150–180 and >180 min). The predictive threshold of ACC duration for each complication was determined by ROC analysis, followed by the analysis of independent predictors of each endpoint by multivariate logistic regression. Results: Intraoperative cardioplegia volume and transfusion requirements were lower in the DN group (p < 0.05). HTK was associated with lower TnI levels and less intra-aortic balloon pump (IABP) requirement at ACC times exceeding 180 min. Markers of myocardial injury were lower in patients with an ACC duration of 120–150 min in favor of HTK. The propensity for ventricular fibrillation after ACC was significantly lower in the DN group. Significantly lower postoperative sodium levels were observed in the HTK group. Prolonged ACC duration was an independent risk factor for LCOS (odds ratio [OR]: 1.023, p < 0.001), VIS > 15 (OR, 1.015; p < 0.001), IABP requirement (OR: 1.020, p = 0.002), and early mortality (OR: 1.016, p = 0.048). Postoperative ejection fraction (EF), troponin I, and CK-MB levels were associated with the development of LCOS and a VIS > 15. Furthermore, according to ROC analysis, HTK cardioplegia was able to tolerate ACC for up to a longer duration in terms of certain complications, suggesting a higher physiological tolerance to ischemia. Conclusions: ACC duration is a strong predictor of major adverse outcomes in adult cardiac surgeries. Although DN cardioplegia is effective and economically advantageous for shorter procedures, HTK may provide superior myocardial protection in operations with long ACC duration. This study supports the need to individualize cardioplegia choice according to ACC duration. Further prospective studies are needed to establish standard dosing protocols and to optimize cardioplegia selection according to surgical duration and complexity.
Aroma precursors of cigars from different tobacco parts and origins, and their correlations with sensory characteristics
Cigars are developing rapidly around the world, but the content characteristics of aroma precursors and their contribution to sensory perception have not been fully elucidated. In this study, 69 aroma precursors from 61 tobaccos of different parts and origins were systematically determined, and the sensory characteristics of middle leaves from different origins and their correlation with aroma precursors were evaluated. The results showed that tobacco parts mainly affected amino acid content, and contents of nicotine, oxalic acid, malic acid, isovaleric acid, cystine, glutarnine, glycine, isoleucine, glutamicacid, asparticacid, and fructose-proline were significantly changed. Tobacco origins mainly influenced the contents of amino acids, polyacids and high fatty acids, and sugar alcohols, and significantly affected the contents of myosmine, anabasine, nonanoic acid, propanetriol, mannitol, mannose, glucose, alanine, arginine, glutarnine, glutamicacid, histidine, serine, threonine, tryptophan, fructose-alanine, and fructose-asparagine. The flavor characteristics were prominent by wood aroma, and the style and quality characteristics varied greatly among different origins of middle leaves. There were 34, 21, and 22 aroma precursors with high correlations with flavor, style, and quality characteristics. This study provides support for regulating the content and coordination of aroma precursors in different tobacco parts and origins to improve sensory characteristics.
Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on electrolyte and acid-base variables in dogs with suspected intracranial hypertension
Abstract Background Hyperosmolar agents frequently are used to decrease intracranial pressure but their effects on electrolyte and acid-base variables have not been prospectively investigated. Objectives Compare duration and magnitude of changes in electrolyte and acid-base variables after hyperosmolar treatment. Animals Twenty-eight client-owned dogs with intracranial hypertension caused by various pathologies. Methods Prospective, randomized, nonblinded, experimental cohort study. Fifteen dogs received a single dose (4 mL/kg) of 7.2% hypertonic saline (HTS), 13 dogs received 20% mannitol (MAN) 1 g/kg IV. Electrolyte and acid-base variables were measured before (T0), and 5 (T5), 60 (T60), and 120 (T120) minutes after administration. Variables were compared between treatments and among time points within treatment groups. Results Mean plasma sodium and chloride concentrations were higher after HTS than MAN at T5 (158 vs 141 mEq/L; 126 vs 109 mEq/L) and significant differences were maintained at all time points. After HTS, plasma sodium and chloride concentrations remained increased from T0 at all time points. After MAN, plasma sodium and chloride concentrations decreased at T5, but these changes were not maintained at T60 and T120. Plasma potassium concentration was lower at T5 after HTS compared with T0 (3.6 vs 3.9 mEq/L) and compared to MAN (3.6 vs 4.1 mEq/L). At T60 and T120, plasma ionized calcium concentration was lower after HTS than MAN (1.2 vs 1.3 mmol/L). No significant differences were found in acid-base variables between treatments. Conclusions and Clinical Importance At the administered dose, dogs receiving HTS showed sustained increases in plasma sodium and chloride concentrations, whereas dogs receiving MAN showed transient decreases. Future studies should assess the effects of multiple doses of hyperosmolar agents on electrolyte and acid-base variables.
Standardizing Intestinal Permeability Assessment: Optimization of Gluten Dose and Urine Collection Times for u-GIP and Lactulose:Mannitol Ratio in Healthy Volunteers
Urinary gluten immunogenic peptides (u-GIPs) have been proposed as a complementary marker to classical intestinal permeability tests based on lactulose, mannitol, and the lactulose:mannitol ratio (LMR). However, the effects of gluten dose, urine collection interval, and sampling strategy on their performance remain insufficiently defined. This study evaluated these variables to support protocol standardization. Data from four standardized protocols including 46 healthy adults exposed to 0, 2, 4, or 10 g of gluten were analyzed. All participants ingested fixed doses of lactulose and mannitol. Urine was collected cumulatively (0–6 h and 0–15 h) or by individual voids. u-GIP levels were measured by lateral-flow immunoassay, and lactulose and mannitol by ion chromatography. u-GIP excretion showed a clear dose dependence. Lactulose excretion increased transiently only at the 10 g dose during the 0–6 h interval, while mannitol excretion and LMR were unaffected. The u-GIP excretion index showed linear proportionality at the 2 g and 4 g doses but exhibited saturation kinetics at the 10 g dose. The 4 g dose showed the lowest interindividual variability. Sampling strategies yielded equivalent results. A 4 g gluten challenge combined with a 6 h urine collection demonstrated effectiveness in healthy volunteers and may be suitable for clinical application. Further research involving larger cohorts of both healthy individuals and patients with intestinal hyperpermeability is required to validate this method.