THE STABILITY OF ENDOGENOUS AND EXOGENOUS CORTICOTROPHIN IN RAT PLASMA AS ESTABLISHED BY A BIOASSAY IN INTACT RATS

1968 ◽  
Vol 41 (4) ◽  
pp. 491-497 ◽  
Author(s):  
H. D. PURVES ◽  
NANCY E. SIRETT
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Rat Plasma ◽  
Significant Loss ◽  
Working Standard ◽  
The Stability ◽  
Saline Medium ◽  
Intact Rats

SUMMARY Corticotrophin (ACTH) activity in rat plasma, both endogenous (adrenalectomized rat plasma) and exogenous (International Working Standard, 1962), has been assayed in dexamethasone-treated rats and the stability studied under various conditions of storage. Exogenous ACTH added to rat plasma and assayed immediately had only 76% of the activity of the same ACTH dissolved in gelatine acid saline medium. This difference is ascribed to the effects of the medium and not to inactivation. When allowance was made for the effects of the medium on potency, added ACTH showed a similar stability on incubation or storage to endogenous ACTH. For endogenous ACTH the following loss of activity was found in vitro: after 45 min. at 37°, 64%; after 1 day at room temperature, more than 85%; after 1 day at 3°, 58%. No loss of potency was detected on storage at −17° for 18 months. It is concluded that plasma can be frozen, stored at low temperature, and thawed without significant loss of corticotrophic potency provided that the blood is chilled as soon as drawn and the subsequent operations performed expeditiously.

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

scholarly journals The Formation of Chitosan-Coated Rhamnolipid Liposomes Containing Curcumin: Stability and In Vitro Digestion

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 560
Author(s):  
Wei Zhou ◽  
Ce Cheng ◽  
Li Ma ◽  
Liqiang Zou ◽  
Wei Liu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Functional Foods ◽  
Positive Charge ◽  
Physical Stability ◽  
In Vitro Digestion ◽  
Salt Addition ◽  
High Transformation ◽  
Liposomal Delivery ◽  
The Stability

There is growing interest in developing biomaterial-coated liposome delivery systems to improve the stability and bioavailability of curcumin, which is a hydrophobic nutraceutical claimed to have several health benefits. The curcumin-loaded rhamnolipid liposomes (Cur-RL-Lips) were fabricated from rhamnolipid and phospholipids, and then chitosan (CS) covered the surface of Cur-RL-Lips by electrostatic interaction to form CS-coated Cur-RL-Lips. The influence of CS concentration on the physical stability and digestion of the liposomes was investigated. The CS-coated Cur-RL-Lips with RL:CS = 1:1 have a relatively small size (412.9 nm) and positive charge (19.7 mV). The CS-coated Cur-RL-Lips remained stable from pH 2 to 5 at room temperature and can effectively slow the degradation of curcumin at 80 °C; however, they were highly unstable to salt addition. In addition, compared with Cur-RL-Lips, the bioavailability of curcumin in CS-coated Cur-RL-Lips was relatively high due to its high transformation in gastrointestinal tract. These results may facilitate the design of a more efficacious liposomal delivery system that enhances the stability and bioavailability of curcumin in nutraceutical-loaded functional foods and beverages.

Stability of Donepezil in an Extemporaneously Prepared Oral Liquid

2006 ◽  
Vol 19 (5) ◽  
pp. 282-285 ◽  
Author(s):  
Weeranuj Yamreudeewong ◽  
Eric Kurt Dolence ◽  
Deborah Pahl
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Storage Time ◽  
Microbial Growth ◽  
Storage Period ◽  
Significant Loss ◽  
Ambient Room Temperature ◽  
Oral Liquid ◽  
Liquid Preparation ◽  
The Stability

The stability of donepezil in an extemporaneously prepared oral liquid was studied. An aqueous liquid formulation of donepezil was prepared by reconstituting the powder from triturated 5-mg tablets with equal amounts of deionized water and 70% sorbitol solution with an expected donepezil concentration of 1 mg/mL. Polyethylene terephthalate plastic bottles containing donepezil liquid preparation were stored at ambient room temperature (22° C-26° C) and in the refrigerator (4° C-8° C). After a storage time of 1, 2, 3, and 4 weeks, donepezil liquid samples were analyzed in triplicate for donepezil concentrations by high-performance liquid chromatography. The concentrations of donepezil were found to be within the acceptable limit (± 10% of the initial concentration) in all test samples, which indicated that donepezil liquid preparation was stable at room temperature and in the refrigerator for up to 4 weeks. In addition, our study findings indicated that there was no microbial growth in the extemporaneously prepared donepezil liquid preparation after a storage period of 4 weeks in the refrigerator. In summary, the results of our study revealed that donepezil is stable (no significant loss of donepezil concentration and no microbial growth) in an extemporaneously prepared oral liquid when stored in the refrigerator for up to 4 weeks.

scholarly journals Synthesis and Characterization of Novel Copolymeric Resveratrol Conjugates

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yan-Jing Ng ◽  
Heather A. E. Benson ◽  
David H. Brown ◽  
Yan Chen
Keyword(s):  
Micelle Formation ◽  
Rat Plasma ◽  
The Body ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
The Stability ◽  
Chain Lengths ◽  
Cardioprotective Drug

Resveratrol (RSV), naturally found in plants, is known to have health benefits and has been proposed as a potential anticancer and cardioprotective drug. However, due to its molecular structure, it undergoes rapid metabolism in the body resulting in low bioavailability. Novel polymeric methoxy-poly(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-PCL) RSV conjugates with varying PCL chain lengths have been synthesised and formulated into micelles and/or nanoparticles for preliminaryin vitrostability studies. RSV conjugated with mPEG2000-PCL9500 was found to have improved solubility and stability of RSV as compared to RSV alone. The length of the PCL chain was found to affect the micelle formation, hence the stability in physiological buffers and rat plasma.

scholarly journals Formulation and Evaluation of Ethosomal Nanoparticles of Avobenzone for Improved Sunscreen Efficacy

2021 ◽  
Vol 70 (1) ◽  
Author(s):  
Sumit Kumar Nagle ◽  
Mansi Gupta ◽  
Deepak Kumar Basedia ◽  
Dubey B.K.
Keyword(s):  
Propylene Glycol ◽  
Room Temperature ◽  
Ethanol Concentration ◽  
Sun Protection ◽  
Irregular Shape ◽  
Good Protection ◽  
In Vitro Permeation ◽  
Egg Membrane ◽  
The Stability

Ethosomes entrapping avobenzone were prepared using cold method and the effect of varying concentration of ethanol was considered for obtaining an optimized formulation. Lecithin (2%w/w) was used as the phospholipid to provide the structure to the vesicles and propylene glycol (10%) was used as the permeating agent. The vesicles were found to be of spherical to irregular shape ranged from 1.11 µm to 1.6 µm in size. The drug entrapment in the ethosomes was studied by analyzing the unentrapped drug spectrophotometrically. The in vitro permeation study suggested that the maximum permeation in the egg membrane occurred in AET3 (0.40 mg/cm2) with 30% ethanol concentration. It was observed that only about 2% degradation occurred at room temperature and all formulations were almost stable at 8° and 4° with only 1.3% degradation of avobenzone thereby proving the stability of the developed system. The best ethosomal formulation (AET3) was incorporated into gel base to obtain sunscreen gels and the results revealed a good protection of the ethosomal gel when 2% carbopol was used as the gelling base. It could be concluded that incorporation of avobenzone in the ethosomal carrier and formulating the same as gel formulation might help in reducing the dose of avobenzone as well as improving the sunscreen efficacy (sun protection over enhanced duration).

scholarly journals In Vitro and In Vivo Study of the Gastrointestinal Absorption and Metabolisation of Hymenocardine, a Cyclopeptide Alkaloid

Planta Medica ◽  
2017 ◽  
Vol 83 (09) ◽  
pp. 790-796 ◽  
Author(s):  
Emmy Tuenter ◽  
Sebastiaan Bijttebier ◽  
Kenn Foubert ◽  
Annelies Breynaert ◽  
Sandra Apers ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Rat Plasma ◽  
In Vivo Study ◽  
Root Bark ◽  
In Vivo Experiments ◽  
Cyclopeptide Alkaloid ◽  
Blood And Urine Samples ◽  
The Stability

AbstractHymenocardine is a cyclopeptide alkaloid present in the root bark of Hymenocardia acida. In traditional African medicine, the leaves and roots of this plant are used to treat malaria, and moderate in vitro antiplasmodial activity has been reported for hymenocardine. However, in view of its peptide-like nature, potential metabolisation after oral ingestion has to be taken into account when considering in vivo experiments. In this study, the stability and small intestinal absorption of hymenocardine was assessed using an in vitro gastrointestinal dialysis model. In addition, potential liver metabolisation was investigated in vitro by incubation with a human S9 fraction. Moreover, hymenocardine was administered to rats per os, and blood and urine samples were collected until 48 and 24 h after oral administration, respectively. All samples resulting from these three experiments were analyzed by LC-MS. Analysis of the dialysate and retentate, obtained from the gastrointestinal dialysis model, indicated that hymenocardine is absorbed unchanged from the gastrointestinal tract, at least in part. After S9 metabolisation, several metabolites of hymenocardine could be identified, the major ones being formed by the reduction and/or the loss of an N-methyl group. The in vivo study confirmed that hymenocardine is absorbed from the gastrointestinal tract unchanged, since it could be identified in both rat plasma and urine, together with hymenocardinol, its reduction product.

scholarly journals Effect of Doxycycline Microencapsulation on Buccal Films: Stability, Mucoadhesion and In Vitro Drug Release

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 51
Author(s):  
Venu Gopal Reddy Patlolla ◽  
Nikolina Popovic ◽  
William Peter Holbrook ◽  
Thordis Kristmundsdottir ◽  
Sveinbjörn Gizurarson
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
In Vitro Release ◽  
Sodium Thiosulfate ◽  
Scanning Calorimetry ◽  
In Vitro Drug Release ◽  
Metalloproteinase Inhibitors ◽  
The Stability ◽  
Buccal Films

The aim of this work was to stabilize doxycycline in mucoadhesive buccal films at room temperature (25 °C). Since doxycycline is susceptible to degradation such as oxidation and epimerization, tablets are currently the only formulation that can keep the drug fully stable at room temperature, while liquid formulations are limited to refrigerated conditions (4 °C). In this study, the aim was to make formulations containing subclinical (antibiotic) doxycycline concentration that can act as matrix metalloproteinase inhibitors (MMPI) and can be stored at temperatures such as 25 °C. Here, doxycycline was complexed with excipients using three techniques and entrapped into microparticles that were stored at 4 °C, 25 °C and 40 °C. Effect of addition of precomplexed doxycycline microparticles on films: stability mucoadhesion capacity, tensile strength, swelling index and in vitro release was studied. The complexation efficiency between drug-excipients, microparticles and films was studied using Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Two of the films were found to be stable at 4 °C but the film containing microparticle composed of precomplexed doxycycline with β-cyclodextrin, MgCl2, sodium thiosulfate, HPMC and Eudragit® RS 12.5 was found to be stable at 25 °C until 26 weeks. The addition of microparticles to the films was found to reduce the mucoadhesive capacity, peak detachment force, tensile strength and elasticity, but improved the stability at room temperature.

scholarly journals Presence and Stability of SARS-CoV-2 on Environmental Currency and Money Cards

2021 ◽  
Author(s):  
Colleen Newey ◽  
Abigail T Olausson ◽  
Alyssa Applegate ◽  
Ann Aubrey Reid ◽  
Richard A Robison ◽  
...  
Keyword(s):  
Room Temperature ◽  
Credit Cards ◽  
The United States ◽  
Microbial Pathogens ◽  
Rapid Reduction ◽  
Live Virus ◽  
Brigham Young University ◽  
Contagious Nature ◽  
The Stability

The highly contagious nature of SARS-CoV-2 has led to several studies on the transmission of the virus. A little studied potential fomite of great concern in the community is currency, which has been shown to harbor microbial pathogens in several studies. Since the onset of the COVID-19 pandemic, many businesses in the United States have limited the use of banknotes in favor of credit cards. However, SARS-CoV-2 has shown greater stability on plastic in several studies.  Herein, the stability of SARS-CoV-2 at room temperature on banknotes, money cards and coins was investigated. In vitro studies with live virus suggested SARS-CoV-2 was highly unstable on banknotes, showing an initial rapid reduction in viable virus and no viral detection by 24 hours. In contrast, SARS-CoV-2 was far more stable on money cards with live virus detected after 48 hours. Environmental swabbing of currency and money cards on and near the campus of Brigham Young University supported these results, with no detection of SARS-CoV-2 RNA on banknotes, and a low level on money cards. No viable virus was detected on either. These preliminary results suggest that the use of money cards over banknotes in order to slow the spread of this virus may be ill-advised. These findings should be investigated further through larger environmental studies involving more locations.

Stability and Relaxation of Point Defects in amorphous silicon

1992 ◽  
Vol 279 ◽  
Author(s):  
Raymond Lutz ◽  
Laurent J. Lewis
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Amorphous Silicon ◽  
Point Defects ◽  
Room Temperature ◽  
Empirical Potential ◽  
The Stability

ABSTRACTWe have used molecular-dynamics to investigate the stability and relaxation of point defects — vacancies and interstitials — in a model of amorphous silicon, with the interactions between atoms described by the Stillinger-Weber empirical potential. The annihila-tion of point defects has been proposed as an important mechanism by which relaxation proceeds in amorphous silicon. Starting with a Wooten-Winer-Weaire model of a-Si, we “manually” create vacancies in the structure by removing a number of randomly-selected four-fold coordinated atoms. The system is then allowed to relax. Our calculations reveal unambiguously that, of a number of vacancies introduced in the model at low temperature, roughly a third are stable; these anneal out upon heating at room temperature. The vacancies seem, in most cases, to consist of a relatively large empty volume bounded by four atoms of which at least one is undercoordinated. Our study of interstitials seems to indicate that they diffuse through a “jump-and-bump” process, eventually annihilating when a large enough, properly coordinated, vacant volume is encountered.

scholarly journals Overcoming Supply Shortage for SARS-CoV-2 Detection by RT-qPCR

Genes ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 90
Author(s):  
Gustavo Barcelos Barra ◽  
Ticiane Henriques Santa Rita ◽  
Pedro Góes Mesquita ◽  
Rafael Henriques Jácomo ◽  
Lídia Freire Abdalla Nery
Keyword(s):  
Room Temperature ◽  
Limit Of Detection ◽  
Guanidine Hydrochloride ◽  
Significant Loss ◽  
Clinical Samples ◽  
Short Supply ◽  
Qualitative Detection ◽  
Probe Concentration ◽  
Assay Performance ◽  
The Stability

In February 2020, our laboratory started to offer a RT-qPCR assay for the qualitative detection of severe acute respiratory syndrome coronavirus 2. A few months after the assay was released to our patients, some materials, reagents, and equipment became in short supply. Alternative protocols were necessary in order to avoid stopping testing to the population. However, the suitability of these alternatives needs to be validated before their use. Here, we investigated if saliva is a reliable alternative specimen to nasopharyngeal swabs; if 0.45% saline is a reliable alternative to guanidine hydrochloride as a collection viral transport media; the stability of SARS-COV-2 in guanidine hydrochloride and in 0.45% saline for 10 and 50 days at room temperature; and if the primers/probe concentration and thermocycling times could be reduced so as to overcome the short supply of these reagents and equipment, without a significant loss of the assay performance. We found that saliva is not an appropriated specimen for our method—nasopharyngeal swabs perform better. Saline (0.45%) and guanidine hydrochloride have a similar SARS-CoV-2 diagnostic capability as tube additives. Reliable SARS-CoV-2 RNA detection can be performed after sample storage for 10 days at room temperature (18–23 °C) in both 0.45% saline and guanidine hydrochloride. Using synthetic RNA, and decreasing the concentration of primers by five-fold and probes by 2.5-fold, changed the assay limit of detection (LOD) from 7.2 copies/reaction to 23.7 copies/reaction and the subsequent reducing of thermocycling times changed the assay LOD from 23.7 copies/reaction to 44.2 copies/reaction. However, using real clinical samples with Cq values ranging from ~12.15 to ~36.46, the results of the three tested conditions were almost identical. These alterations will not affect the vast majority of diagnostics and increase the daily testing capability in 30% and increase primers and probe stocks in 500% and 250%, respectively. Taken together, the alternative protocols described here overcome the short supply of tubes, reagents and equipment during the SARS-CoV-2 pandemic, avoiding the collapse of test offering for the population: 105,757 samples were processed, and 25,156 SARS-CoV-2 diagnostics were performed from 9 May 2020 to 30 June 2020.

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