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.

Kinetics of the IgG—anti-IgG Reaction, as Evaluated by Conventional and Stopped-Flow Nephelometry

1974 ◽  
Vol 20 (8) ◽  
pp. 1071-1075 ◽  
Author(s):  
John Savory ◽  
Gregory Buffone ◽  
Richard Reich
Keyword(s):  
Polyethylene Glycol ◽  
Data Acquisition System ◽  
Lag Phase ◽  
Stopped Flow ◽  
Kinetic Measurement ◽  
Antigen Concentration ◽  
Specific Proteins ◽  
Rapid Reaction ◽  
Antigen Antibody ◽  
Kinetics Of

Abstract A stopped-flow spectrophotofluorometer equipped with a data-acquisition system was used to study the rate of formation of IgG—anti-IgG complexes by nephelometry. Light-scattering aggregates could be detected within 100 ms. Early rates ( 0-3 s) increased with antigen concentration, while rates during later stages (5-100 s) followed the same trend exhibited by the precipitin curve. Polyethylene glycol (known to exert a profound effect on antigen—antibody reactions) at a concentration of 40 g/liter affected the IgG—anti-IgG reaction as follows: there was an initial lag phase of 5-10 s and a subsequent rapid reaction over the next 20-40 s, characterized by a four-to five-fold enhancement in the amount of light scattered. Our observations demonstrate that centrifugal-analyzer techniques can be used for the kinetic measurement of specific proteins in serum.

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 Kinetics of tau aggregation reveals patient specific tau characteristics among Alzheimer's cases

2021 ◽  
Author(s):  
Tarun V Kamath ◽  
Naomi Klickstein ◽  
Caitlin Commins ◽  
Analiese R Fernandes ◽  
Derek H Oakley ◽  
...  
Keyword(s):  
Growth Phase ◽  
Tau Proteins ◽  
Patient Specific ◽  
Lag Phase ◽  
Plateau Phase ◽  
Kinetic Assay ◽  
Cellular Processes ◽  
Morphological Differences ◽  
Tau Aggregation ◽  
Kinetics Of

Abstract The accumulation of tau aggregates throughout the human brain is the hallmark of a number of neurodegenerative conditions classified as tauopathies. Increasing evidence shows that tau aggregation occurs in a “prion-like” manner, in which a small amount of misfolded tau protein can induce other, naïve tau proteins to aggregate. Tau aggregates have been found to differ structurally among different tauopathies. Recently, however, we have suggested that tau oligomeric species may differ biochemically among individual patients with sporadic Alzheimer disease, and have also showed that the bioactivity of the tau species, measured using a cell-based bioassay, also varied among individuals. Here, we adopted a live-cell imaging approach to the standard cell-based bioassay to explore further whether the kinetics of aggregation also differentiated these patients. We found that aggregation can be observed to follow a consistent pattern in all cases, with a lag phase, a growth phase, and a plateau phase, which each provide quantitative parameters by which we characterize aggregation kinetics. The length of the lag phase and magnitude of the plateau phase are both dependent upon the concentration of seeding-competent tau, the relative enrichment of which differs among patients. The slope of the growth phase correlates with morphological differences in the tau aggregates, which may be reflective of underlying structural differences. This kinetic assay confirms and refines the concept of heterogeneity in the characteristics of tau proteopathic seeds among individuals with Alzheimer’s disease and is a method by which future studies may characterize longitudinal changes in tau aggregation and the cellular processes which may influence these changes.

scholarly journals Insights into the Control of Drug Release from Complex Immediate Release Formulations

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 933
Author(s):  
Runqiao Dong ◽  
James C. DiNunzio ◽  
Brian P. Regler ◽  
Walter Wasylaschuk ◽  
Adam Socia ◽  
...  
Keyword(s):  
Drug Release ◽  
Immediate Release ◽  
Liquid Penetration ◽  
Central Importance ◽  
Water Penetration ◽  
Release Process ◽  
Terahertz Pulsed Imaging ◽  
And Control ◽  
Kinetics Of ◽  
Spray Dried

The kinetics of water transport into tablets, and how it can be controlled by the formulation as well as the tablet microstructure, are of central importance in order to design and control the dissolution and drug release process, especially for immediate release tablets. This research employed terahertz pulsed imaging to measure the process of water penetrating through tablets using a flow cell. Tablets were prepared over a range of porosity between 10% to 20%. The formulations consist of two drugs (MK-8408: ruzasvir as a spray dried intermediate, and MK-3682: uprifosbuvir as a crystalline drug substance) and NaCl (0% to 20%) at varying levels of concentrations as well as other excipients. A power-law model is found to fit the liquid penetration exceptionally well (average R2>0.995). For each formulation, the rate of water penetration, extent of swelling and the USP dissolution rate were compared. A factorial analysis then revealed that the tablet porosity was the dominating factor for both liquid penetration and dissolution. NaCl more significantly influenced liquid penetration due to osmotic driving force as well as gelling suppression, but there appears to be little difference when NaCl loading in the formulation increases from 5% to 10%. The level of spray dried intermediate was observed to further limit the release of API in dissolution.

Effect of Hypertonic Sucrose Upon the Immune Bactericidal Reaction

1970 ◽  
Vol 1 (1) ◽  
pp. 51-55
Author(s):  
Louis H. Muschel ◽  
Linda J. Larsen
Keyword(s):  
Cell Death ◽  
Cell Wall ◽  
Enzymatic Reaction ◽  
Inhibitory Effect ◽  
Lag Phase ◽  
Inner Membrane ◽  
Bactericidal Antibody ◽  
Kinetics Of ◽  
Free Serum ◽  
Supporting Structures

This study was performed to determine the mechanism whereby hypertonic sucrose inhibits the immune bactericidal reaction. Other investigators had postulated that the initial attack of complement (C) on the cell wall was followed with lysozyme-containing whole serum by an enzymatic reaction upon the peptidoglycan substrate resulting in cell death. In the absence of serum lysozyme, secondary lethal changes might occur from damage to the cell's inner membrane as a result of osmotic forces in the presence of a defective cell wall. Hypertonic sucrose giving rise to plasmolysis and protection of the inner membrane was presumed to differentially inhibit the immune response mediated by lysozyme-free serum. The experimental results observed in this investigation have indicated, however, that the inhibitory effect of sucrose upon the bactericidal reaction may be explained simply by its anticomplementary effect and not by any effect on the bacterial cell. This view was supported by the following observations: (i) the comparability of the inhibitory effect of sucrose upon the immune hemolytic and bactericidal reactions, (ii) the comparable percentage loss in bactericidal activity of whole serum and lysozyme-free serum resulting from hypertonic sucrose, (iii) bactericidal antibody titrations were relatively unaffected and C titrations markedly inhibited by sucrose, (iv) the inhibitory effect of sucrose on the bactericidal reaction was unaffected by prior growth of the organism in the presence of sucrose, (v) the kinetics of the bactericidal reactivity of lysozyme-free serum in hypertonic sucrose, compared with whole serum, did not reveal a prolonged lag phase with lysozyme-free serum, but simply diminished reactivity at all times. These observations are compatible with the view that the C attack upon the outer surface of gram-negative bacteria, which plays a part in the cell's permeability control, may account for cell death. In this regard, the immune bactericidal reaction is quite comparable to the lysis of red cells or nucleated cells by C despite the lack of overt lysis in bacteria, probably because of their underlying supporting structures.

STUDY OF THE KINETICS OF DRYING BREWER’S SPENT GRAIN

2020 ◽  
Author(s):  
Т.Г. КОРОТКОВА ◽  
А.С. ДАНИЛЬЧЕНКО ◽  
Н.Ю. ИСТОШИНА
Keyword(s):  
Matter Content ◽  
Dry Matter Content ◽  
Drying Time ◽  
Brewer’S Spent Grain ◽  
Average Value ◽  
Free Moisture ◽  
Before And After ◽  
Spent Grain ◽  
Kinetics Of ◽  
Two Temperature

Исследована кинетика сушки сырой пивной дробины – вторичного продукта ООО «Белореченский пивоваренный завод» (Россия, Краснодарский край). Сушка проведена в двух температурных режимах – 60 и 55°С. Скорость сушильного агента при вынужденной конвекции составляла 4,5 м/с. Содержание сухого вещества определено по ГОСТ 31640–2012 в лабораторных условиях и составило 12,9%. Измерение убыли массы при сушке проведено с интервалом 5 мин. Общее время сушки навески пивной дробины в количестве 50 г – 420 мин при режиме 50°С, 360 мин – при 60°С. Среднее значение конечной влажности пивной дробины составило 11,85%. Построены кривые сушки и скорости сушки. Скорость сушки при удалении свободной влаги в первом периоде сушки, мин–1: при 60°С – 3,5, при 55°С – 3,0. Установлено, что содержание связанной влаги составляет в среднем 57% от массы влаги в навеске пивной дробины, свободной влаги – 43%. Анализ структуры навески пивной дробины под микроскопом до сушки и после нее подтвердил факт, что в исследованном материале количество связанной влаги больше, чем свободной. Наличие частиц размером 5–7 мм свидетельствует о значительном количестве клеточной влаги в неразрушенных капиллярах. Дальнейшее совершенствование технологии переработки пивной дробины должно быть направлено на разрушение клеточной структуры материала после его механического обезвоживания. The kinetics of drying of the crude brewer’s spent grain – a secondary product of LLC «Belorechensky brewery» (Russian Federation, Krasnodarregion) has been studied. Drying is carried out in two temperature modes – 60 and 55°C. The speed of the drying agent under forced convection was 4,5 m/s. The dry matter content was determined according to GOST 31640–2012 in laboratory conditions and was 12,9%. Measurement of mass loss during drying was performed at an interval of 5 min. The total drying time of the brewer’s spent grain sample in the amount of 50 gis 420 min at 50°C, 360 min – at 60°C. The average value of the final moisture content of brewer’s spent grain made up 11,85%. Curves of drying and drying speed are constructed. Drying speed when removing free moisture in the first drying period, min–1: at 60°C – 3,5, at 55°C – 3,0. It was found that the content on average of bound moisture is 57% of the mass of moisture in brewer’s spent grain, free moisture – 43%. Analysis of the structure sample of brewer’s spent grain a microscope before and after drying confirmed the fact that the amount of bound moisture in the studied material is greater than the amount of free moisture. The presence of particles of 5–7 mm in size indicates a significant amount of cellular moisture in undisturbed capillaries. Further improvement of the technology for processing brewer’s spent grain should be aimed at destroying the cellular structure of the material after its mechanical dehydration.

Adaptation to high-fat diet accelerates emptying of fat but not carbohydrate test meals in humans

2002 ◽  
Vol 282 (2) ◽  
pp. R366-R371 ◽  
Author(s):  
K. E. Castiglione ◽  
N. W. Read ◽  
S. J. French
Keyword(s):  
Gastric Emptying ◽  
Dietary Intake ◽  
Test Meal ◽  
High Fat Diet ◽  
Lag Phase ◽  
High Fat ◽  
Free Living ◽  
Gastric Emptying Rate ◽  
High Carbohydrate ◽  
Before And After

Previous work has shown that the gastric emptying rate in animals and humans can adapt due to previous dietary intake. The present study investigated whether adaptation in gastric emptying rate due to consumption of a high-fat diet (HFD) is nutrient specific in humans. Gastric emptying of high-fat and high-carbohydrate test meals was measured (using gamma scintigraphy) before and after consumption of an HFD for 14 days in eight free-living male volunteers. Visual analog ratings of appetite were recorded throughout each test. There was no effect of HFD on any parameters of gastric emptying rate (lag phase, half-emptying time, and linear emptying rate) measured for carbohydrate test meals. HFD led to an acceleration of the linear emptying rate of the high-fat test meal (0.36 vs. 0.47%/min; P < 0.05). All meals reduced appetite ratings, but there were no differences between tests. These results support our previous findings of accelerated gastric emptying of high-fat test meals following an HFD and show that these changes appear to be nutrient specific, confirming recent studies in rats.

scholarly journals Preparation and Assessment of Some Characteristics of Nanoparticles Based on Sodium Alginate, Chitosan, and Camellia chrysantha Polyphenols

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Phu Hoang Luong ◽  
Thuy Chinh Nguyen ◽  
The Dan Pham ◽  
Do Mai Trang Tran ◽  
Thi Ngoc Lien Ly ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Release Kinetics ◽  
Release Kinetic ◽  
Ionic Gelation ◽  
Visible Spectroscopy ◽  
Polyphenol Content ◽  
Release Process ◽  
Kinetics Of ◽  
Scanning Electron

This paper presents the characteristics, morphology, and properties of alginate/chitosan/polyphenol nanoparticles, in which polyphenols were extracted from Camellia chrysantha leaves collected in Tam Dao district, Vinh Phuc province (Vietnam). The alginate/chitosan/polyphenol nanoparticles were prepared by ionic gelation method at different polyphenol content. The characteristics and morphology of these nanoparticles were investigated using infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM). Release kinetic of polyphenols from the alginate/chitosan/polyphenol nanoparticles was conducted in simulated human body fluids. The release kinetics of polyphenols from the above nanoparticles were also evaluated and discussed. The experimental results showed that the release process of polyphenols from the nanoparticles was dependent on three factors: time, pH of solution, and amount of polyphenols.

scholarly journals Substantiation of the sell-by date of food products

2020 ◽  
Vol 52 (1) ◽  
pp. 59-63
Author(s):  
S.M. Kuzminskiy ◽  
T.V. Adamchuk ◽  
О.М. Holinko ◽  
N.P. Levytska
Keyword(s):  
Food Products ◽  
Storage Conditions ◽  
Lag Phase ◽  
Contamination Level ◽  
Second Phase ◽  
Phase Duration ◽  
Normative Documents ◽  
Culture Development ◽  
Storage Distribution ◽  
Kinetics Of

Objective of the Work. The overview of current methodical approaches for experimental substantiation of the sell-by date of food products. Methods and Materials. Data analysis of scientific literature and normative documents on methods of substantiation of the sell-by date of food products. Results and Discussion. Sell-by date is a period since product’s manufacture, during which it maintains its safety and quality (including nutritional value) within reasonably foreseeable conditions of storage, distribution and consumption. In the case of new products (recipes) introduction it is necessary to review the sell-by date, and its extending as the need arises. The main aspects of microbiological substantiation of the sell-by date of food products are considered. The identification of microbial hazard for particular product is the first phase of the work. The second phase of the work is to determine the kinetic parameters of precise microorganism’s accumulation to maximum permitted level within regulated and aggravated conditions of product’s storage. Conclusions. In the process of microbiological substantiation of the sell-by date of food products it should be taken into consideration the presence of leading pathogen and causative microorganisms of microbial spoilage, the initial contamination level, the lag phase duration of germ culture development, variations between strains, the kinetics of microorganisms’ accumulation within the product in real and aggravated storage conditions, the indetermination connected with biological nature of microorganisms and their inhomogeneous allocation within the product, the limitation for shortcut research methods (if applicable). The decision rule should be based on the consumer’s risk concept. Key Words: food products, sell-by date, substantiation, microbiological indicators.

scholarly journals Effect of Lyophilization on Survivability and Growth Kinetic of Trichoderma Strains Preserved on Various Agriculture By-Products

2017 ◽  
Vol 66 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Danuta Witkowska ◽  
Katarzyna Buska-Pisarek ◽  
Wojciech Łaba ◽  
Michał Piegza ◽  
Anna Kancelista
Keyword(s):  
Survival Rate ◽  
Growth Kinetic ◽  
High Growth ◽  
High Growth Rate ◽  
Actual Number ◽  
Viable Cells ◽  
Colony Forming Units ◽  
Beet Pulp ◽  
Kinetics Of ◽  
By Products

Growth kinetics of four Trichoderma strains was tested on lignocellulosic by-products in solid state fermentation (SSF). The strains were also analyzed for their survival rate and growth after lyophilization on these carriers. All applied monocomponent and bicomponent media were substrates for the production and preservation of Trichoderma biomass. However, the maximum number of colony forming units (CFU/g dm) was acquired on bicomponent media based on dried grass and beet pulp or grass with corn cobs, when compared to monocomponent media. Although the process of lyophilization reduced the survival rate by 50%-60%, the actual number of viable cells in obtained biopreparations remained relatively high (0.58 × 108 - 1.68 × 108 CFU/g dm). The studied strains in the preserved biopreparations were characterized by a high growth rate, as evaluated in microcultures using the Bioscreen C system.

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