scholarly journals Evaluation of mesostructured silica materials with different structures and morphologies as carriers for quercetin and naringin encapsulation

2021 ◽  
Author(s):  
Sonia Morante-Zarcero ◽  
Alba Endrino ◽  
Natalia Casado ◽  
Damián Pérez-Quintanilla ◽  
Isabel Sierra
Keyword(s):  
Biomedical Applications ◽  
Textural Properties ◽  
Molecular Size ◽  
Release Process ◽  
Mesostructured Silica ◽  
Before And After ◽  
The Stability ◽  
First Time ◽  
Kinetics Of ◽  
Potential Use

AbstractTwo mesostructured silicas with wormhole-like pore arrangement (HMS and MSU-2) were synthesized and evaluated for the first time as carriers for the encapsulation of two bioactive flavonoids (quercetin and naringin). For comparative purposes, a hexagonal mesostructured SBA-15 silica type frequently used as encapsulating support was also prepared and tested. All the materials were characterized before and after the loading with the analytes. Different silica/analyte ratios were evaluated to determine the loading and encapsulation kinetics of the different materials. Both flavonoids were successfully loaded inside the pores of the three silicas. The quercetin loading capacity of HMS was higher than SBA-15 and MSU-2 silicas, whereas for naringin SBA-15 and MSU-2 were slightly more effective. These differences could be attributed to the molecular size of the analytes and the textural properties of the different materials. Nevertheless, HMS was the silica that enabled to release the highest amount of both analytes. Thus, it could be considered a suitable carrier of these flavonoids and an alternative to other materials such as SBA-15. Moreover, the release process was performed under controlled conditions (pH 2.0 and 7.4) to simulate digestive conditions. Quercetin was delivered faster and more efficiently from the encapsulated at pH 2.0, whereas no differences were observed for naringin at both pHs. Finally, the antioxidant activity of the resulting encapsulates was determined. The results obtained suggested the potential use of wormhole-like mesostructured silicas as carriers to enhance the stability and bioavailability of flavonoids, so they can be used in future food and biomedical applications.

scholarly journals STUDIES ON THE MECHANISMS OF HYPERSENSITIVITY PHENOMENA

1964 ◽  
Vol 120 (4) ◽  
pp. 507-530 ◽  
Author(s):  
Lawrence M. Lichtenstein ◽  
Abraham G. Osler
Keyword(s):  
Histamine Release ◽  
Divalent Cations ◽  
Lag Phase ◽  
Antigen Concentration ◽  
Release Process ◽  
Viable Cells ◽  
Cellular Sensitivity ◽  
Before And After ◽  
Release Histamine ◽  
Kinetics Of

Human leukocytes, isolated from the blood of ragweed-sensitive donors, release histamine upon reaction with a purified protein antigen derived from this pollen. The release process has been studied with washed cells suspended in a defined, serum-free medium. Physiologic levels of pH, ionic strength, and temperature, as well as both calcium and magnesium, are required for optimal cellular reactivity. The level of cellular sensitivity of approximately 200 ragweed-sensitive donors has been ascertained, and the kinetics of the release process studied. The rate of histamine release is a function of antigen concentration, but even with a large excess of this reagent it is impossible to abolish a lag phase. Chelation of the divalent cations or a decrease in the reaction temperature may be utilized to stop the reaction. These measures are effective both before and after the initiation of histamine release. Diminished cellular reactivity (desensitization) has been achieved by several procedures. These have in common the addition of antigen to cells in an environment deficient in but a single respect, followed by a restoration of optimal conditions. The significance of these data has been discussed and it has been proposed that immunologically induced histamine release is an active, enzymatically mediated process which occurs as a multistep response of viable cells to a specific antigenic stimulus.

scholarly journals Progestogens Are Metabolized by the Gut Microbiota: Implications for Colonic Drug Delivery

Pharmaceutics ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 760
Author(s):  
Zoe Coombes ◽  
Vipul Yadav ◽  
Laura McCoubrey ◽  
Cristina Freire ◽  
Abdul Basit ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Oral Delivery ◽  
Cytochrome P450 Enzymes ◽  
Colonic Delivery ◽  
Delivery Methods ◽  
Colonic Drug Delivery ◽  
Colonic Flora ◽  
The Stability ◽  
First Time ◽  
Kinetics Of

Following oral administration, the bioavailability of progestogens is very low and highly variable, in part due to metabolism by cytochrome P450 enzymes found in the mucosa of the small intestine. Conversely, the mucosa in the colon contains much lower levels of cytochrome P450 enzymes, thus, colonic delivery of progestogens may be beneficial. Microbiota in the colon are known to metabolize a great number of drugs, therefore, it is important to understand the stability of these hormones in the presence of colonic flora before developing formulations. The aim of this study was to investigate the stability of three progestogens: progesterone, and its two synthetic analogues, medroxyprogesterone acetate (MPA) and levonorgestrel (LNG), in the presence of human colonic microbiota. Progesterone, MPA, and LNG were incubated in mixed fecal inoculum (simulated human colonic fluid) under anerobic conditions. Progesterone was completely degraded after 2 h, whereas levels of MPA and LNG were still detectable after 24 h. The half-lives of progesterone, MPA, and LNG in fecal inoculum were 28, 644, and 240 min, respectively. This study describes the kinetics of colonic microbial metabolism of these hormones for the first time. MPA and LNG show promise for delivery to the colon, potentially improving pharmacokinetics over current oral delivery methods.

scholarly journals Study on Precipitation and Growth of TiN in GCr15 Bearing Steel during Solidification

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1463 ◽  
Author(s):  
Bin Li ◽  
Xiao Shi ◽  
Hanjie Guo ◽  
Jing Guo
Keyword(s):  
Growth Kinetics ◽  
Stability Diagram ◽  
Bearing Steel ◽  
Kinetic Calculation ◽  
Gcr15 Bearing Steel ◽  
Before And After ◽  
Solving Equations ◽  
The Stability ◽  
Kinetics Of ◽  
Ti Content

In this paper, the precipitation thermodynamics and growth kinetics of TiN inclusions in GCr15 bearing steel during solidification were calculated in more detail. A more reasonable formula for calculating the segregation of the solute elements was adopted and the stability diagram of TiN precipitation considering solidification segregation was given. By solving equations, the change of the solute element content before and after TiN inclusion precipitation was calculated, and the results were substituted into the kinetic formula of the inclusion growth, which made the kinetic calculation more accurate. Results showed that the most effective way to reduce the precipitation of TiN is to increase the cooling rate and decrease the contents of Ti and N in steel. The effect of Ti content on the size of TiN inclusions is greater than that of N content.

scholarly journals Solubility, Rheology, and Coagulation Kinetics of Poly-(O-Aminophenylene)Naphthoylenimide Solutions

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2454
Author(s):  
Ivan. Y. Skvortsov ◽  
Valery G. Kulichikhin ◽  
Igor I. Ponomarev ◽  
Lydia A. Varfolomeeva ◽  
Mikhail S. Kuzin ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Time Window ◽  
Polymer Concentration ◽  
Effect Of Temperature ◽  
Coagulation Bath ◽  
Continuous Polymerization ◽  
Coagulation Kinetics ◽  
The Stability ◽  
First Time ◽  
Kinetics Of

The effect of temperature and storage time at a constant temperature on the stability of poly-(o-aminophenylene)naphthoylenimide solutions in N-methylpyrrolidone has been analyzed using rotational rheometry. A temperature–time window beyond which an irreversible change in the viscoelastic properties of solutions due to cumulative reactions of continuous polymerization and possible intramolecular cyclization has been detected. The influence of polymer concentration and its molecular weight on the rheological properties of solutions determining the choice of methods for their processing into fibers and films has been investigated. The effect of non-solvents (water and ethanol) additives on the rheological properties of solutions and the kinetics of their coagulation has been studied. Dosed addition of non-solvent into the solution promotes a significant increase in the viscoelasticity up to gelation and phase separation. Non-solvent presence in the polymer solutions reduces the activity of the solvent, accelerates the movement of the diffusion front at coagulation, and minimizes the number of macro defects. The combination of parameters under investigation renders it possible for the first time to develop new principles modifying dopes for wet spinning into aqueous or ethanol coagulation bath and finally to obtain a heat- and fire-resistant polynaphthoylenebenzimidazole fibers.

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

Untersuchungen zur Quantifizierung der Änderung der Skelettmuskeldurchblutung nach Gefäßrevaskularisationen mit einem 99mTechnetiummarkierten Tracer

1990 ◽  
Vol 29 (05) ◽  
pp. 215-220 ◽  
Author(s):  
R. Benning ◽  
K. Nagel ◽  
M. Jugenheimer ◽  
S. Fischer ◽  
S. Worthmann ◽  
...  
Keyword(s):  
Transluminal Angioplasty ◽  
Lower Limbs ◽  
Surgical Patients ◽  
Treadmill Test ◽  
Negative Results ◽  
Clinical Observations ◽  
Before And After ◽  
Comparative Results ◽  
First Time ◽  
Percutaneous Transluminal

A new 99mTc-labelled tracer (99mTc-Sestanriibi) was used for the first time to demonstrate the perfusion of the skeletal muscle. In 16 patients with obstructive atherosclerosis of the lower limbs the change of perfusion of thigh and lower leg was studied with SPECT before and after vascular surgery (n = 11) or percutaneous transluminal angioplasty (n = 5). Comparative results of scintigraphic measurements and clinical observations (ancle-arm pressure, treadmill test) in 10 surgical patients (14 operated legs) showed correct positive or negative results in 86% (12/14).

Zeolites Fit For A Crown: Probing Host-Guest Interactions with Thermogravimetric Methods

2018 ◽  
Author(s):  
Asel Sartbaeva ◽  
Paul R. Raithby ◽  
Remi Castaing ◽  
Antony Nearchou
Keyword(s):  
Mass Spectrometry ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Petrochemical Industry ◽  
Rational Use ◽  
New Methodologies ◽  
First Time ◽  
Kinetics Of

Through a combination of thermogravimetry, mass spectrometry and differential thermal analysis, we demonstrate for the first time that all four zeolites show experimental differences in their host-guest interactions with 18C6. In addition, we have estimated the kinetics of 18C6 decomposition, which is a technique that has not been applied to zeolites previously. Using these findings as a toolkit, a more rational use of OSDAs can be utilised to prepare designer zeolites. Furthermore, the new methodologies presented herein can be applied to current zeolites, such as MFI-type zeolites used in the petrochemical industry.

Trombodynamics Method in the Assessment of Coagulation Parameters in Psychopharmacotherapy of Endogenous Mental Disorders

Psychiatry ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 16-25
Author(s):  
N. S. Karpova ◽  
O. S. Brusov ◽  
I. V. Oleichik ◽  
M. I. Faktor ◽  
N. S. Levchenko ◽  
...  
Keyword(s):  
Mental Disorders ◽  
Response To Therapy ◽  
Procoagulant Activity ◽  
Coagulation Activity ◽  
Continuous Type ◽  
Chronic Neuroinflammation ◽  
Psychopharmacological Treatment ◽  
Before And After ◽  
First Time ◽  
Schizotypal Disorder

Background: currently, it has been proven that the pathogenesis of endogenous mental disorders is associated with the process of neuroinflammation in the brain of patients. It is also known that chronic neuroinflammation, accompanied by a violation the permeability of the blood-brain barrier. It is accompanied by the activation of platelets that generate procoagulant microparticles, which leads to a disturbance of the hemostasis system, causing an increase in blood clotting in patients. Objective: to investigate the dynamics of procoagulant activity of blood in patients with endogenous mental disorders before and after psychopharmacotherapy.Patients and methods: the study included 185 patients aged 16 to 64 years with the following mental disorders: schizophrenia with attack-like/attack-progressive/continuous type of course (F20.00–2), affective disease (F31.1–5; F32.0–3; F33.0–3), schizotypal disorder with affective fluctuations (F21.3–4). The thrombodynamic test (TD) was performed on T-2 Trombodynamis device according to the manufacturer’s instructions (Hemacore LLC, Moscow, Russia). All patients received standard pharmacotherapy according to their condition.Results: a significant decrease of procoagulant activity of spontaneous clots in the patients’ blood after psychopharmacological treatment is observed. Our data on the positive dynamics of changes in the values of TD test’s indicators in most of the examined patients suggest that a decrease in the coagulation activity of the patients’ blood as a result of treatment may be associated with the anti- inflammatory effect of antipsychotics and antidepressants.Conclusion: for the first time, it was shown that there is a positive dynamic in changing the values of the main parameters of the TD test in most patients with endogenous mental diseases. The results of TD tests can be the basis for monitoring the response to therapy.

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