Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Biofluid”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1976

Simultaneous determination of meperidine and normeperidine in biofluids.

A method employing solvent extraction and gas-liquid chromatography has been developed for the simultaneous determination of meperidine and its N-demethylated metabolite, normeperidine, in biofluids. Normeperidine is analyzed as the heptafluorobutyryl derivative. Using a flame ionization detector, the lower limit of sensitivity of the method is 0.02 mug/ml of biofluid for both compounds. Samples of plasma obtained from obstetrical patients, following a single therapeutic dose, were found to contain higher levels of meperidine than concurrent samples of amniotic fluid. Normeperidine could not be detected in either biofluid after a single dose. There is, however, a gradual accumulation of normeperidine in plasma after repeated doses as determined in samples from cancer patients. The method can also be used to determine the disposition of merperidine and the accumulation of normeperidine in the cat.

Amniotic Fluid↗
PubMed1991

Simple and accurate determination of methylpyrazines in biofluids using high-performance liquid chromatography.

The determination of six methylpyrazines was performed using high-performance liquid chromatography (HPLC). Methylpyrazines were simultaneously extracted and injected onto a silica gel column with a syringe-type minicolumn packed with diatomaceous earth granules. The extraction-injection solvent used was dichloromethane and the mobile phase solvent for HPLC was dichloromethane containing 0.08% of 1.65 M ammonia solution and 0.5% of methanol. Methylpyrazines were detected using an ultraviolet detector set at 275 nm. Linear relationships between the amount of sample and peak height were confirmed from 50 ng/ml to 10 micrograms/ml of the biofluids. When an aliquot of 10 microliters of biofluid was introduced to the minicolumn, the detection limit of methylpyrazines was as low as 30 ng/ml with each pyrazine derivative. The method is simple and accurate and is thus applicable to pharmacokinetic studies which are performed on animals. The results showed that the possible pharmacological effects of methylpyrazines might be evaluated pharmacokinetically using this newly developed technique.

Animals↗
PubMed2022

Direct capture and sequencing reveal ultra-short single-stranded DNA in biofluids.

Cell-free DNA (cfDNA) has become the predominant analyte of liquid biopsy; however, recent studies suggest the presence of subnucleosomal-sized DNA fragments in circulation that are likely single-stranded. Here, we report a method called direct capture and sequencing (DCS) tailored to recover such fragments from biofluids by directly capturing them using short degenerate probes followed by single strand-based library preparation and next-generation sequencing. DCS revealed a new DNA population in biofluids, named ultrashort single-stranded DNA (ussDNA). Evaluation of the size distribution and abundance of ussDNA manifested generality of its presence in humans, animal species, and plants. In humans, red blood cells were found to contain abundant ussDNA; plasma-derived ussDNA exhibited modal size at 50 nt. This work reports the presence of an understudied DNA population in circulation, and yet more work is awaiting to study its generation mechanism, tissue of origin, disease implications, etc.

Biological sciences↗
PubMed2026

Integrated landscape of salivary metagenome and multi-biofluid metabolome characterizes a microbial-metabolic axis in upper gastrointestinal cancer progression.

BACKGROUND: Upper gastrointestinal cancer (UGIC) imposes a major global health burden, yet the stage-specific molecular changes along the microbial-metabolic axis remain limited understood. We aimed to delineate this molecular landscape across UGIC progression and evaluate its potential as non-invasive methods for precision screening. RESULTS: Derived from a multi-center population-based UGIC screening program, we enrolled 420 individuals, stratified into normal, low-grade intraepithelial neoplasia (LGIN), high-grade intraepithelial neoplasia (HGIN), and UGIC (n = 105 per group). Integrated salivary metagenomics and paired salivary/plasma metabolomics were performed to capture local and systemic dysregulation. We uncovered distinct stage-specific divergence during UGIC progression: profound remodeling of the salivary microbiota (104 differential species) and salivary metabolomics (80 differential metabolites) initiated early at the LGIN stage, whereas plasma metabolic dysregulation (40 differential metabolites) peaked significantly later at the HGIN stage. Integrative analysis revealed salivary microbiota related more closely with salivary metabolome than plasma metabolome. Moreover, statistical evidence suggested that dysbiotic salivary microbiota was associated with altered lysine- and tryptophan-related catabolic pathways converging on Acetyl-CoA-related metabolic nodes, supporting a potential metabolic mechanism in precancerous lesions. Finally, the discriminative model integrating metagenomic and metabolomic markers demonstrated promising diagnostic performance in distinguishing these precancerous lesions (LGIN: area under the curve [AUC] = 0.83; HGIN: AUC = 0.77) and UGIC (AUC = 0.76) from normal. CONCLUSION: This study characterizes a stage-specific microbial-metabolic axis that facilitates the comprehensive understanding of UGIC pathogenesis. These multi-biofluid signatures offer a promising non-invasive triage strategy for detecting precancerous lesions and optimizing endoscopic resource allocation. Video Abstract.

Female↗
PubMed1992

Biofluid dynamics at arterial bifurcations.

Hemodynamics has long been suspected of being involved in arterial diseases, e.g., atherosclerosis. Seemingly good correlation between the atherosclerosis localization and the flow disturbance around bends and bifurcations in large arteries has prompted many studies of blood flow around those regions. This article reviews and critiques biofluid studies at various arterial bifurcations. Both experimental and theoretical models vary greatly in the major assumptions and parameters. The issues discussed include: possible errors from two-dimensional models, the validity of steady flow studies, the existence and influence of the secondary flow, effects of non-Newtonian blood rheology, influences from arterial wall distensibility, effects of the Reynolds number, effects of the area ratio, effects of the Womersley number, effects of corner curvatures, effects of bifurcation angle, errors in the measurement and calculation of wall shear rate, and the possible existence of turbulence.

Animals↗
PubMed1992

Determination of hydrazine in biofluids by capillary gas chromatography with nitrogen-sensitive or mass spectrometric detection.

Plasma and liver levels of hydrazine were determined at 10, 30, 90 and 270 min in rats given 0.09, 0.27, 0.84 and 2.53 mmol of hydrazine per kg body weight orally by capillary gas chromatography-mass spectrometry of its pentafluorobenzaldehyde adduct (DFBA, m/z 388) using selected ion monitoring with 15N2-labelled hydrazine as the internal standard (adduct, m/z 390). The mean half-life for hydrazine in the plasma was approximately 2 h but varied with dose. Urinary excretion (0-24 h) of hydrazine and its metabolite acetylhydrazine were determined employing nitrogen-phosphorus detection of the adducts utilising a novel internal standard, pentafluorophenylhydrazine, the adduct of which structurally resembles DFBA. The fraction of the original dose excreted as hydrazine (and acetylhydrazine) declined with increasing dose.

Animals↗
PubMed1975

Simultaneous determination of acetylmethadol and its active riotransformation products in human biofluids.

A method employing solvent extraction and gas-liquid chromatography has been developed for the quantitative determination of acetylmethadol simultaneously with its two major biotransformation products, noracetylmethadol and dinoracetylmethadol. Noracetylmethadol and dinoracetylmethadol are analyzed following their conversion to the corresponding amides. The amide structure is confirmed by the use of chemical ionization mass spectroscopy and infrared spectroscopy. The method can be used to determine the concentration of acetylmethadol and these compounds in plasma samples from acetylmethadol maintenance subjects. Methadol and normethadol do not attain neasurable plasma levels. Urine contains predominantly noracetylmethadol and dinoracetylmethadol. Evidence was also obtained for the urinary excretion of acetylmethadol, methadol and normethadol. A mean quantity equal to 28% of the administered dose was excreted in the urine of a 48-h dosing interval as acetylmethadol and metabolites.

Biotransformation↗
PubMedDate not supplied

Direct detection of new flucytosine metabolites in human biofluids by 19F nuclear magnetic resonance.

19F nuclear magnetic resonance was used for the analysis of flucytosine (FC; 5-fluorocytosine) metabolites in biological fluids of a patient with cryptococcal meningitis who was intravenously injected with this drug at a daily dose of 7.5 g (2.5 g at 8-hr intervals). This method allows a direct, simultaneous, and quantitative determination of all the fluorinated metabolites of FC, in the range of sensitivity allowed by the spectrometer (sensitivity threshold, 0.01 mM). In urine, in addition to the already reported metabolites [unmetabolized FC and alpha-fluoro-beta-alanine (FBAL)], three new metabolites were identified: a glucuronide of FC (GLFC), 6-hydroxy-5-fluorocytosine (60HFC), and fluoride ion F-. The same metabolites (except F-) were found in plasma. In cerebrospinal fluid, only unchanged FC and GLFC were observed. The total urinary excretion during an 8-hr period between two injections of FC was 100.4% of the injected dose. Unchanged FC was the major excretory product accounting for 96.1% of the total. GLFC and 6OHFC made up, respectively, 2.7% and 1.2% of the excreted metabolites. The proportions of F- and FBAL were very low, respectively, 0.3% and 0.1% of the excreted metabolites. The global urinary excretion over a 24-hr period was 102% of the injected dose. The proportions of metabolites were very close to those obtained for the 8-hr period. In plasma, the proportions of metabolites were analogous to those determined in urine. In cerebrospinal fluid, GLFC represents 1% of the fluorinated metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Fluids↗