In vivo profiling of phytocannabinoids in Cannabis spp. varieties via SPME-LC-MS analysis

BACKGROUND

In vivo solid-phase microextraction (SPME) is a minimally invasive, non-exhaustive sample-preparation technique that facilitates the direct isolation of low molecular weight compounds from biological matrices in living systems. This technique is especially useful for the analysis of phytocannabinoids (PCs) in plant material, both for forensic purposes and for monitoring the PC content in growing Cannabis spp. plants. In contrast to traditional extraction techniques, in vivo SPME enables continuous tracking of the changes in the level of PCs during plant growth without the need for plant material collection. In this study, in vivo SPME utilizing biocompatible C18 probes and liquid-chromatography coupled to quadrupole time-of flight mass spectrometry (LC-Q-TOF-MS) is proposed as a novel strategy for the extraction and analysis of the acidic forms of five PCs in growing medicinal cannabis plants.

RESULTS

The SPME method was optimized by testing various parameters, including the extraction phase (coating), extraction and desorption times, and the extraction temperature. The proposed method was validated with satisfactory analytical performance regarding linearity (10-3000 ng/mL), limits of quantification, and precision (relative standard deviations below 5.5 %). The proposed method was then successfully applied for the isolation of five acidic forms of PCs, which are main components of growing medicinal cannabis plants. As a proof-of-concept, SPME probes were statically inserted into the inflorescences of two varieties of Cannabis spp. plants (i.e., CBD-dominant and Δ9-THC-dominant) cultivated under controlled conditions for 30 min extraction of tetrahydrocannabinolic acid (Δ9-THCA), cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), cannabiviarinic acid (CBVA), and tetrahydrocannabivarinic acid (THCVA).

SIGNIFICANCE AND NOVELTY

The results confirmed that the developed SPME-LC-Q-TOF-MS method is a precise and efficient tool that enables direct and rapid isolation and analysis of PCs under in vivo conditions. The proposed methodology is highly appealing option for monitoring the metabolic pathways and compositions of multiple PCs in medicinal cannabis at different stages of plant growth.

Evaluation of N4-hydroxycytidine incorporation into nucleic acids of SARS-CoV-2-infected host cells by direct measurement with liquid chromatography-mass spectrometry

Molnupiravir, an orally administered prodrug of β-d-N4-hydroxycytidine (NHC), is incorporated into newly synthesized RNA by viral RNA-dependent RNA polymerase (RdRp). It is used for treatment of SARS-CoV-2 infections. Incorporation of NHC triphosphate into viral RNA inhibits replication of the virus, at least in part by introducing deleterious mutations. However, there is limited information on NHC incorporation into host RNA and reports on the risk of mutagenicity that molnupiravir/NHC pose to the host are conflicting. We used two liquid chromatography-mass spectrometry (LC-MS) methods to evaluate the incorporation of NHC into RNA and DNA of host Vero E6 cells in a SARS-CoV-2 infection model. To test this, host and viral RNA were degraded to their ribonucleosides, while host DNA was degraded to deoxyribonucleosides. Subsequently, nucleic acid constituents were analyzed by LC-MS, which offers specific, direct, and quantitative determination of incorporation. Our findings revealed concentration dependent NHC incorporation into host cell RNA in both infected and uninfected cell cultures, reaching a maximum of 1 in 7,093 bases. Analysis of host DNA revealed no presence of deoxy-N4-hydroxycytidine down to a detection limit of 1 in 133,000 bases. Our findings therefore suggest minimal to no NHC incorporation into host DNA, indicating a low probability of significant host cell mutagenicity associated with its use.

Novel mass spectrometry-based assay for thymidylate synthase activity

Thymidylate synthase (TS) is an enzyme responsible for the conversion of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP), with the co-substrate 5,10-methylenetetrahydrofolate (5,10-CH2-THF) as the methyl donor. TS is the only enzyme capable of de novo biosynthesis of dTMP in humans, a nucleotide crucial for DNA synthesis and therefore cell proliferation and survival. As such, TS is a major drug target in chemotherapy by compounds such as 5-fluorouracil. Due to the clinical and physiological importance of TS, the ability to accurately assay its activity is crucial. Several assays have been developed for this purpose, relying on spectrophotometry or radioisotope labeling methods. In this study, we have developed a liquid chromatography - mass spectrometry-based method for assessing TS activity by direct and specific measurement of the reaction product, dTMP. The assay was tested on mouse liver homogenates. We noted that excessive 5,10-CH2-THF concentration (400 µM) led to substrate inhibition and therefore 200 µM was used. The activity assayed at 1 µM dUMP was linear with protein content and time (up to 60 min) and was 0.56 ± 0.12 pmol/mg protein/min, in line with previously reported values. Additionally, by using a high mass resolution Orbitrap instrument side reactions were monitored, revealing major changes in folate pools and nucleotide metabolism. These findings highlight the value of the developed TS assay for routine TS activity monitoring in complex matrixes such as clinical material.

The impaired distribution of adenosine deaminase isoenzymes in multiple sclerosis plasma and cerebrospinal fluid

Background

Adenosine deaminase (ADA) via two isoenzymes, ADA1 and ADA2, regulates intra- and extracellular adenosine concentrations by converting it to inosine. In the central nervous system (CNS), adenosine modulates the processes of neuroinflammation and demyelination that together play a critical role in the pathophysiology of multiple sclerosis (MS). Except for their catalytic activities, ADA isoenzymes display extra-enzymatic properties acting as an adhesion molecule or a growth factor.

Aims

This study aimed to explore the distribution and activity of ADA1 and ADA2 in the plasma and the CSF of MS patients as well as in the human brain microvascular endothelial cells (HBMEC), human brain vascular pericytes and human astrocytes.

Methods and results

The enzyme assay following reverse phase-high performance liquid chromatography (HPLC) analysis was used to detect the ADA1 and ADA2 activities and revealed an increased ratio of ADA1 to ADA2 in both the plasma and the CSF of MS patients. Plasma ADA1 activity was significantly induced in MS, while ADA2 was decreased in the CSF, but significance was not reached. The brain astrocytes, pericytes and endothelial cells revealed on their surface the activity of ADA1, with its basal level being five times higher in the endothelial cells than in the astrocytes or the pericytes. In turn, ADA2 activity was only observed in pericytes and endothelial cells. Stimulation of the cells with pro-inflammatory cytokines TNFα/IL17 for 18 h decreased intracellular nucleotide levels measured by HPLC only in pericytes. The treatment with TNFα/IL17 did not modulate cell-surface ATP and AMP hydrolysis nor adenosine deamination in pericytes or astrocytes. Whereas in endothelial cells it downregulated AMP hydrolysis and ADA2 activity and upregulated the ADA1, which reflects the ADA isoenzyme pattern observed here in the CSF of MS patients.

Conclusion

In this study, we determined the impaired distribution of both ADA isoenzymes in the plasma and the CSF of patients with MS. The increased ADA1 to ADA2 ratio in the CSF and plasma may translate to unfavorable phenotype that triggers ADA1-mediated pro-inflammatory mechanisms and decreases ADA2-dependent neuroprotective and growth-promoting effects in MS.

Improvement of speech recognition by nonlinear noise reduction

The success of nonlinear noise reduction applied to a single channel recording of human voice is measured in terms of the recognition rate of a commercial speech recognition program in comparison to the optimal linear filter. The overall performance of the nonlinear method is shown to be superior. We hence demonstrate that an algorithm that has its roots in the theory of nonlinear deterministic dynamics possesses a large potential in a realistic application.

Combustion process in a spark ignition engine: dynamics and noise level estimation

We analyze the experimental time series of internal pressure in a four cylinder spark ignition engine. In our experiment, performed for different spark advance angles, apart from the usual cyclic changes of engine pressure we observed additional oscillations. These oscillations are with longer time scales ranging from one to several hundred engine cycles depending on engine working conditions. Based on the pressure time dependence we have calculated the heat released per combustion cycle. Using the time series of heat release to calculate the correlation coarse-grained entropy we estimated the noise level for internal combustion process. Our results show that for a larger spark advance angle the system is more deterministic.

Noise-level estimation of time series using coarse-grained entropy

We present a method of noise-level estimation that is valid even for high noise levels. The method makes use of the functional dependence of coarse-grained correlation entropy K2(epsilon ) on the threshold parameter epsilon. We show that the function K2(epsilon ) depends, in a characteristic way, on the noise standard deviation sigma. It follows that observing K2 (epsilon ) one can estimate the noise level sigma. Although the theory has been developed for the Gaussian noise added to the observed variable we have checked numerically that the method is also valid for the uniform noise distribution and for the case of Langevin equation corresponding to the dynamical noise. We have verified the validity of our method by applying it to estimate the noise level in several chaotic systems and in the Chua electronic circuit contaminated by noise.

[Treatment of external postoperative fistulas of the gastrointestinal tract]

In the years 1985-1996 82 patients with postoperative external fistulas of gastrointestinal tract (pefgt) were treated in the Department of General Surgery of Hospital in Olsztyn. The age of the patient varied from 18 to 70 years. 37 patients were women and 45 man. Volume of excreted fluid fluctuated from 100 ml to 3000 ml per day. The most frequent cause of pefgt was dehiscence of the anastomosis of jejunum in 31 patients, and operations of complications of gastric or duodenal ulcer disease in 30 patients. 54 patients underwent medical treatment. It was based on compensation of disorders in water and electrolyte balance and acid-base equilibrium, nutritional treatment, protection of the skin, suction of the excreted fluid, controlling of foci of infection, rehabilitation. 7 patients were reoperated for the purpose of closing the fistula and 21 to drain abscess or to stop bleeding. 57 (70%) out of 82 patients recovered, 25 (30%) died. In this number 14 patients among 54 treated conservatively and 11 out from 28 operated. The most frequent cause of death was sepsis (15 patients). The conservative treatment including TPN is successful in majority of patients with pefgt and indispensable in patients treated operatively. Special attention should be given for coexisting intraperitoneal abscessa, peritonitis and sepsis.