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Results for “Stability analysis”

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At least 91 records · Page 5Linked to original sources
PubMed1978

Fenoprofen: drug form selection and preformulation stability studies.

Several fenoprofen salts were prepared to obtain the most acceptable form for an oral dosage formulation. Thermal analysis techniques were used to compare stabilities of the water of hydration in different salt forms and to assess the effects of the water of hydration on compatibility with propoxyphene and codeine salts. Photodegradation products of fenoprofen were isolated and identified, and their relevance to product formulation was evaluated.

Amines↗
PubMed1978

[Adaptation of an entirely enzymatic triglyceride assay to the GSA II Greiner. Application to the study of the stability of triglycerides, and factors causing interference in the analysis (author's transl)].

The assay of triglycerides by an entirely enzymatic pathway was adapted for use on the GSA II Greiner. The method requires only 20 microliters of biological material. The reaction time is short: 8 min at 37 degrees C. The coefficient of variation does not exceed 6% over a period of one month. Linearity of the measurements was verified up to a level of 4 mmol/l. It was shown that the free glycerol level should be systematically measured and deducted from that of the total glycerol to assure accurate results. The stability of the plasma triglycerides was investigated as a function of the length and temperature of storage (+4 degrees C and -196 degrees C). The free glycerol increases as a function of time, whereas the level of triglycerides stays constant. Haemoglobin and various medicaments, in particular, hypolipemiants and hypoglycemiants, did not interfere.

Autoanalysis↗
PubMed2025

KDM3B Regulates Postradiation Fibrotic Responses in Prostate Stroma via N6-methyladenosine Modification of LOX.

PURPOSE: Genome-wide association studies have uncovered single-nucleotide polymorphisms (SNPs) linked to radiation therapy (RT)-induced toxicities in patients with prostate cancer. SNP rs17599026, located in intron 21 of the KDM3B gene, has been associated with late-onset urinary toxicity, with an increased frequency of urination observed 2 years post-RT compared with pretreatment conditions. This study aimed to explore the underlying mechanisms driving this association. METHODS AND MATERIALS: A clustered regularly interspaced short palindromic repeats-dead Cas9 prime editing system was used to mimic KDM3B genetic variants in prostate stromal cell lines. Murine models with wild-type and heterozygous Kdm3b genotypes were used to assess fibrosis following radiation. RNA immunoprecipitation, transcript stability assays, and protein analysis elucidated the role of N6-methyladenosine (m6A) modification in regulating lysyl oxidase (LOX) expression. α-ketoglutarate (α-KG) supplementation was tested for its effects on KDM3B protein stability, LOX expression, and fibrosis mitigation. RESULTS: The rs17599026 SNP reduced KDM3B protein expression via circular RNA and microRNA-mediated mechanisms, leading to decreased m6A modification and increased stability of LOX messenger RNA. Elevated LOX expression promoted collagen cross-linking and fibrosis in prostate stroma. α-KG supplementation restored KDM3B protein levels, reduced LOX expression, and mitigated fibrosis in vitro and in vivo. CONCLUSIONS: KDM3B genetic variations influence radiation-induced fibrosis through posttranscriptional regulation of LOX. Dietary α-KG supplementation may serve as a mechanism-based strategy to alleviate radiation toxicity in patients with prostate cancer, offering a potential therapeutic pathway to improve treatment outcomes.

Male↗
PubMed2025

COG6 is an essential host factor for influenza A virus infection.

Influenza A virus (IAV) relies on the host cellular machinery to support its replication. Understanding these host dependencies can inform the development of novel antiviral strategies. In this study, we identified conserved oligomeric Golgi complex subunit 6 (COG6) as a novel host factor critical for IAV replication through a genome-wide clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) knockout screen. Disruption of COG6 significantly impaired viral replication. Mechanistically, COG6 supports IAV replication via two distinct means. First, consistent with the role of the COG complex in Golgi homeostasis, COG6 is required for the proper presentation of surface sialic acids, the primary receptor for IAV entry. Second, COG6 deficiency unexpectedly led to lysosome-dependent degradation of viral proteins. Notably, lysosomal activity was also upregulated in IAV-infected wild-type cells, albeit to a lesser extent than in COG6-deficient cells. Treatment with lysosomal inhibitors rescued viral protein stability in COG6 knockout cells. Protein interaction analysis further demonstrated that COG6-mediated stabilization of viral proteins did not rely on viral protein-COG6 interaction, refuting the hypothesis that COG6 acts as a shield factor to protect viral protein from lysosomal degradation. Moreover, knockout of other COG subunits produced similar antiviral effects, suggesting that an intact COG complex is required for IAV replication. Together, these findings uncover a critical role of the COG complex in regulating IAV replication and highlight a previously unappreciated functional link between the Golgi and lysosomes that could be exploited for treating IAV infections.IMPORTANCEDespite advances in virology, numerous host determinants facilitating influenza A virus (IAV) pathogenesis remain uncharacterized. Our study establishes conserved oligomeric Golgi complex subunit 6 (COG6) as a critical host factor promoting IAV infection through complementary mechanisms: receptor modulation and viral protein stabilization. This represents the first demonstration that the COG complex regulates viral pathogenesis through proteostasis mechanisms, fundamentally expanding our understanding of host-virus interactions at the organelle interface. These findings not only provide new perspectives on viral exploitation of Golgi trafficking networks but also identify potential therapeutic targets against evolving influenza strains.

Influenza A virus↗
PubMed1978

Time-dependent increase in the stability of collagen fibrils formed in vitro. I. Effects of pH and salt concentration on the dissolution of the fibrils.

The time-dependent increase in stability, as measured in terms of the rate of dissolution, of collagen fibrils formed in vitro from pepsin-treated collagen was significantly affected only by temperature, and not by either ionic strength or pH. This is in contrast with collagen fibril formation, a process which is greatly affected by ionic strength and pH. Within the range of temperature 29-37 degrees C, lower temperature caused slower fibril formation and faster fibril stabilization. These results suggest that the intermolecular interactions involved in stabilizing collagen fibrils are entirely different from those involved in fibril formation. Based on kinetic analysis of the dissolution and stabilization of the fibrils, it is proposed that collagen molecules first form unstable fibrils which become gradually stabilized on prolonged incubation, without necessarily introducing covalent cross-links.

Animals↗
PubMed1977

Gas chromatographic analysis of acetophenone oxime and its metabolites.

A gas-liquid chromatographic (GLC) method has been developed for monitoring the metabolic reduction of acetophenone oxime or oxidative metabolism of the corresponding amine, alpha-methylbenzylamine in liver homogenates. The oxime, amine, n-hydroxy-alpha-methylbenzylamine and acetophenone are quantitatively determined after GLC separation of components with temperature programming on an SP-2401-DB-coated column. The first three compounds were silylated with N,O-bis(trimethylsilyl)-acetamide prior to chromatographic analysis to enhance the stability and improve the chromatographic properties of these components. The effluent gas was monitored with flame ionization detection, and permitted quantitation of components at sub-microgram/ml levels with reproducibility between injections of +/-2%. The optimal composition of enantiomeric mixtures of (R,S)-alpha-methylbenzylamines formed during metabolic reduction of acetophenone oximes were determined by conversion to diastereomeric amides and subsequent GLC analysis.

Acetophenones↗
PubMed1977

[New methods of coagulation analysis using chromogenic substrates].

The available assay systems for the determination of coagulation factors based on clotting methods are unsatisfactory, despite efforts to stabilize and to standardize them. Analysis by means of chromogenic peptide substrates offers new possiblities for routine diagnostics, and for fundamental research. The development of these new methods, however, is at an early stage.

Blood Coagulation Factors↗
PubMed1977

Conversion of hydroxo(aquo) cobalamin to sulfitocobalamin in the absence of light: a reaction of importance in the identification of the forms of vitamin B12, with possible clinical significance.

During determinations of the forms of vitamin B12 in foods and human tissues several samples yielded a growth zone on bioautography which was distinct from those due to methylcobalamin, adenosylcobalamin, hydroxocobalamin, or cyanocobalamin. The material responsible for this growth zone was identified as sulfitocobalamin and the mechanisms in its formation from hydroxocobalamin involve absence of light and the presence of bisulphite ions derived from atmospheric sulfur dioxide or indigenous sulfite ions. The formation of sulfitocobalamin during the extraction of cobalamins from foods and tissues can be prevented by reception and homogenization of the material in an ammonia buffer instead of water; the hydroxocobalamin is then converted to ammonia cobalamin, which is more resistant to attack by (bi)sulfite ions. The conversion of hydroxo(aquo)cobalamin to sulfitocobalamin in the dark can be rapid, and materials for analysis should be placed in the ammonia buffer before darkroom work is begun. The rapid conversion of hydroxo(aquo)cobalamin to sulfitocobalamin in the dark raises the possibility that hydroxocobalamin in foods may be converted to the less well absorbed sulfitocobalamin in the upper gastrointestinal tract.

Animals↗
PubMed1979

The effects of mutagen-sensitive mutants of Drosophila melanogaster in nonmutagenized cells.

The effects of 13 mutagen-sensitive (mus) mutants (representing seven loci) on mitotic chromosome stability in nonmutagenized cells have been examined genetically. To do this, mus-bearing flies heterozygous for the recessive somatic-cell marker, multiple wing hairs (mwh), were examined for increased frequencies of mwh clones in the wing blade. Mutants at the mus-103, mus-104 and mus-106 loci do not affect the frequency of mwh clones, while mus-101, mus-102, mus-105 and mus-109 alleles cause increases in the frequency of mwh clones. These data show that the wild-type alleles of latter four loci specify functions that are required for chromosome stability in nonmutagenized cells. Analysis of the size distribution of mwh clones produced by these mutants suggests that most chromosome instability caused by these mutants is the consequence of chromosome breakage; in the presence of mus-105 and mus-109 alleles a small fraction of the mwh clones are produced by an event (mitotic recombination, mutation, nondisjunction) that produces euploid clones. To inquire whether any of the extant alleles of the mus-101, mus-102, mus-105 and mus-109 loci might be leaky alleles of loci that carry out essential mitotic functions, chromosome stability in females homozygous for alleles of these loci has been compared to that of females carrying one dose of a mutant over a deficiency for that mus locus. These comparisons show that the extant alleles at the mus-101, mus-109 and mus-105 loci are all leaky mutants. It is suggested that all three of these loci may specify essential mitotic functions.

Animals↗
PubMed2026

Generational variation and stabilization in resynthesized allotetraploid Brassica juncea derived from diploid progenitors B. rapa and B. nigra.

BACKGROUND: Polyploidy is a major driver of plant evolution and crop improvement, generating novel variation in morphology, physiology, and agronomic traits. Brassica juncea (AABB, 2n = 36), a natural allotetraploid derived from B. rapa (AA) and B. nigra (BB), is an important oilseed and vegetable crop; however, its narrow genetic base limits further breeding gains. Resynthesized B. juncea (RBJ), developed from known progenitors, provides a tractable system to investigate polyploid stabilization, trait diversification, and generational variation. This study evaluated RBJ across nine generations (F1-S8) to elucidate generational variation in morphological, molecular, cytological, and oil content traits during progressive stabilization. RESULTS: Substantial variation was observed for key yield-related traits, including siliqua length, seeds per siliqua, and thousand-seed weight. High estimates of heritability, genotypic variance, and genetic advance indicated their potential utility in selection based improvement. Comparative analyses revealed a clear generational progression, characterized by relatively enhanced performance in early generations, increased recombination-driven variability in intermediate generations, and the partial stabilization of several traits in later generations. Generation mean analysis suggested the involvement of additive, dominance, and epistatic gene effects in trait inheritance. Molecular analysis using SSR markers confirmed the amphidiploid origin and genomic integrity of RBJ generations. Cytological assessments, pollen viability assays, and flow cytometric analysis collectively demonstrated stable chromosome numbers, improved fertility, and maintenance of ploidy stability across successive generations. CONCLUSIONS: The study provides valuable insights into the generational variation and stabilization of morphological, molecular, and oil content traits in resynthesized B. juncea. The findings suggest that variability arising from polyploidization and interspecific hybridization undergoes gradual reorganization across successive generations, leading to increased trait stabilization and more consistent expression of selected agronomic characteristics. Collectively, these results contribute to the understanding of early stabilization processes in RBJ, highlighting resynthesized polyploids as useful systems for studying variation and stabilization in allopolyploid crops.

Mustard Plant↗
PubMed1976

GLC determination of aprindine: quantitation and stability measurement.

A GLC method of analysis of a new antiarrhythmic agent, aprindine, is described. The raw material of the new drug substance, supplied as the hydrochloride salt, is dissolved in deionized water, and the base is liberated by a 10% aqueous solution of sodium carbonate. aprindine is extracted with chloroform and mixed with the internal standard, 5alpha-cholestane. GLC is perfomed on a glass column packed with 3.8% W-98 on Chromosorb W-HP. Quantitation is achieved by computer calculation of the peak area ratios. GLC-mass spectral analysis indicates that the observed peak is that of aprindine, with a molecular ion at m/e 322. The retention times of aprindine and the internal standard are 2.0 and 5.8 min, respectively. All synthetic precursors show a shorter retention time than aprindine. This GLC method is applied to the quantitative determination of aprindine as raw material and in capsule and ampul formulations. The method is also used to measure the stability of aprindine to acid, base, dry, heat, refluxing, and UV light and to pH variations.

Aprindine↗
PubMed1977

[S-Methylmethionine content in plant and animal tissues and stability during storage].

The content of S-methylmethionine SMM in the extracts of 53 plant and 13 animal products by means of ion exchange clean-up procedure followed by two dimensional thin layer chromatography has been investigated. It was found that the richest plant SMM sources (in mg/100 g) are cabbage (53-104), kohlrabi (81-110), turnip (51-72), tomatoes (45-83), celery (38-78), leeks (66-75), garlic-leafs (44-64), beet (22-37), raspberries (27) and strawberries (14-25). The animal products are poor in SMM. The control of the plants rich in SMM during a storage for 6 months (autumn, winter) in the soil showed average decreases as follows: celery 38%, kohlrabi 39%, turnip 43%, and leeks 32%. A storage of cabbage with uncontrolled temperature resulted in a decrease of 62%, in a storehouse (0-1 degrees C) of 34% SMM.

Drug Stability↗
PubMed1979

Rapid determination of quinine in soft drinks by reversed phase ion pair chromatography.

Quinine can easily be determined in soft drinks by means of reversed-phase ion-pair chromatography. Sample preparation is not necessary. Quinine is detected by fluorescence and UV spectrophotometry by continuous monitoring of the column effluent. A rectilinear response is obtained in the concentration range of 20--100 mg/l. The complete assay procedure takes about 8 min.

Beverages↗
PubMed1979

[Vitamin A in irradiated foodstuffs (author's transl)].

Vitamin A losses induced by 10 MeV electrons in cream cheese, calf liver sausage, pig liver, whole egg powder and margarine continued to increase during storage for 4--8 weeks in presence of air. Thus vitamin A loss in sausage irradiated with 5 Mrad was 22% on the day after irradiation, 61% after 4 weeks. Irradiation and storage at 0 degrees C instead of at ambient temperature reduced these losses considerably. Exclusion of air (vacuum, nitrogen) or irradiation on dry ice (approx. -80 degrees C) were even more effective in preventing destruction of vitamin A. After 4 weeks of storage, cream cheese irradiated at 5 Mrad had lost 60% when irradiated and stored in air at ambient temperature, 20% in nitrogen atmosphere, 5% in vacuum package, and 5% when irradiated on dry ice and stored at ambient temperature.

Drug Stability↗
PubMed1978

Cell specific effect of ecdysone on RNA synthesis in the differentiated salivary gland of Acricotopus lucidus.

The influence of the steroid hormone ecdysone on the RNA metabolism of 2 cell types (main and anterior lobe) of the Acricotopus salivary gland has been investigated. Ecdysone has been found to increase the synthesis of 4S RNA and poly(A)+ RNA in the main lobe, while the anterior lobe remained unaffected by the same treatement. The stimulated poly(A)+ RNA is characterized by its relatively low cytoplasmic turnover. No evidence has been found for the stimulation of ribosomal RNA synthesis in both cell types. Analysis of the metabolic stability of cytoplasmic poly(A)+ RNA after ecdysone administration revealed a different response of the main and anterior lobe cells. Only in the anterior lobe ecdysone causes a shortening of the lifetime of that part of poly(A)+ RNA which is peculiar in its early appearance and relatively low stability in the cytoplasm.

Animals↗