Tissue Distribution Research Articles

In vitro ADME, mouse pharmacokinetics of LD14b, and bioanalysis of a novel aβ 17β-HSD10 modulator for the treatment of Alzheimer’s disease

LD14b is an amyloid-β (Aβ) 17β-hydroxysteroid dehydrogenase type 10 (Aβ-17β-HSD10) protein-protein interaction modulator that shows promising in vitro and ex vivo activity to rescue Aβ-induced mitochondrial dysfunction, Aβ-induced toxicity, and Aβ-mediated inhibition of estradiol synthesis. The current study investigated in vitro human S9 fractions metabolic stability, apparent permeability, human and mouse plasma protein binding, in vivo pharmacokinetics, and tissue distribution in Balb/cJ mice. A fast (8-min), sensitive, reliable, and reproducible LC-MS/MS method was developed and validated over the dynamic range of 1-1000 ng/mL for the quantification of LD14b in different biological matrices (plasma, liver, kidney, brain, lungs, heart). LD14b was metabolically stable in human liver S9 fractions with 70% remaining after 90 minutes of incubation, showed intermediate apparent permeability of 3.55 × 10−06 cm/s and 6.16 × 10−06 cm/s for apical-to-basolateral (A-to-B) and basolateral-to-apical (B-to-A), respectively across the Caco-2 monolayer, and was medium/highly bound to human plasma proteins (84.1%), mouse plasma proteins (85.7%), and mouse brain homogenate (95.4%). LD14b showed an in vivo predicted % absorption of 52% in Balb/cJ mice and was well-distributed to the peripheral tissues (liver, kidney, lungs, and heart) including the brain.

Application of newly developed and validated UPLC-MS/MS method for pharmacokinetic study of ROS1/NTRK inhibitor taletrectinib in beagle dog plasma

Taletrectinib is a potent selective ROS and pan-NTRK tyrosine kinase inhibitor (TKI) and has been developed to treat non-small cell lung cancer (NSCLC). To facilitate pharmacokinetic and toxicokinetic studies of taletrectinib, we developed a procedure for ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to detect the plasma level of taletrectinib in dogs. This assay procedure was validated in compliance with FDA guidance. The dog plasma samples were spiked with internal standard (IS), followed by protein precipitation, and analyzed using a Waters ACQUITY BEH C18 column coupled to a Thermo triple quadrupole mass spectrometer. Separation was executed using the acetonitrile-0.1 % formic acid solution with gradient elution, at a flow rate of 0.4 mL/min. Taletrectinib and IS were monitored by multiple reaction monitoring (MRM) with m/z 406.2 > 349.2 and m/z 441.2 > 138.1, respectively. The procedure demonstrated excellent linearity with a correlation coefficient greater than 0.999 within the concentration range of 0.2–200 ng/mL. The inter- and intra-day accuracy ranged from −5.25 % to 5.26 %, and the precision was below 6.39 %. Acetonitrile-mediated protein precipitation showed high extraction efficiency and a recovery above 85 %. The procedure was then applied to quantify taletrectinib in beagle dog plasma after oral and intravenous doses and achieved success. The obtained pharmacokinetic parameters indicated high bioavailability of taletrectinib (>85 %) and extensive tissue distribution (>40 L/kg).

The ABCG2 Transporter Affects Plasma Levels, Tissue Distribution and Milk Secretion of Lumichrome, a Natural Derivative of Riboflavin.

The ABCG2 membrane transporter affects bioavailability and milk secretion of xenobiotics and natural compounds, including vitamins such as riboflavin. We aimed to characterize the in vitro and in vivo interaction of ABCG2 with lumichrome, the main photodegradation product of riboflavin, which has proven in vitro anti-cancer activity and a therapeutical role in antibacterial photodynamic therapy as an efficient photosensitizer. Using MDCK-II polarized cells overexpressing murine Abcg2 and human ABCG2 we found that lumichrome was efficiently transported by both variants. After lumichrome administration to wild-type and Abcg2-/- mice, plasma AUC20-120 min was 1.8-fold higher in Abcg2-/- mice compared with wild-type mice. The liver and testis from Abcg2-/- mice showed significantly higher lumichrome levels compared with wild-type, whereas lumichrome accumulation in small intestine content of wild-type mice was 2.7-fold higher than in Abcg2-/- counterparts. Finally, a 4.1-fold-higher lumichrome accumulation in milk of wild-type versus Abcg2-/- mice was found. Globally, our results show that ABCG2 plays a crucial role in plasma levels, tissue distribution and milk secretion of lumichrome potentially conditioning its biological activity.

Synthesis, Preclinical Toxicity, and Biodistribution of [18F]AVT-011 to Assess the P-Glycoprotein Function.

Introduction: Many studies have reported the role of P-glycoprotein (Pgp) in chemoresistance in various pathological conditions such as cancer and neurodegenerative diseases, such as Alzheimer's. In this study, we are reporting the high-performance liquid chromatography (HPLC)-based purification of fluorine-18 [18F]AVT-011 and its preclinical evaluation. Methods: AVT-011 was labeled with 18F using the nucleophilic substitution method by heating the reaction mixture at 110°C for 10 min, followed by purification using preparative HPLC and C18ec cartridge. The in vitro cell uptake study was carried out in U87 cells with and without an inhibitor. The preclinical toxicity was carried out in CD1 mice in three groups, including control, AVT-011 treated, and [18F]AVT-011 treated. The biodistribution study was done in CD1 mice (n = 12) after intravenous injection of 4-6 MBq [18F]AVT-011, and mice were sacrificed at various time intervals. A dose of 3.7 ± 0.7 MBq of [18F]AVT-011 was injected intravenously in the healthy Swiss albino mice, and the whole-body micro-positron emission tomography was acquired at 0-, 30-, 60-, and 120-min postinjection. Results: The radiochemical purity of [18F]AVT-011 was 97 ± 1.5% as evaluated by radio-HPLC with a yield of 14 ± 2% and was stable up to 95% under in vitro conditions in blood and invivo conditions up to 4 h. The in vitro cell uptake study showed a significant difference in control (27.4 ± 2.1%) and blocked U987 cells (73.2 ± 3.2%) after incubation of 120 min. The tissue distribution in mice showed the highest uptake in the liver (17.3 ± 2.4%), kidneys (16.6 ± 3.1%), lungs (10.4 ± 2.9%), and spleen (5.6 ± 0.8%) at 15 min, and the activity was washed out with time. The radioactivity cleared through the hepatorenal pathway. The animal imaging study also demonstrates a similar biodistribution pattern. Conclusions: [18F]AVT-011 showed higher specific activity than the cartridge-based method but showed similar biological activity.

Pharmacokinetics and pharmacodynamics of bacteriophage therapy: a review with a focus on multidrug-resistant Gram-negative bacterial infections.

SUMMARYDespite the early recognition of their therapeutic potential and the current escalation of multidrug-resistant (MDR) pathogens, the adoption of bacteriophages into mainstream clinical practice is hindered by unfamiliarity with their basic pharmacokinetic (PK) and pharmacodynamic (PD) properties, among others. Given the self-replicative nature of bacteriophages in the presence of host bacteria, the adsorption rate, and the clearance by the host's immunity, their PK/PD characteristics cannot be estimated by conventional approaches, and thus, the introduction of new considerations is required. Furthermore, the multitude of different bacteriophage types, preparations, and treatment schedules impedes drawing general conclusions on their in vivo PK/PD features. Additionally, the drawback of acquired bacteriophage resistance of MDR pathogens with clinical and environmental implications should be taken into consideration. Here, we provide an overview of the current state of the field of PK and PD of bacteriophage therapy with a focus on its application against MDR Gram-negative infections, highlighting the potential knowledge gaps and the challenges in translation from the bench to the bedside. After reviewing the in vitro PKs and PDs of bacteriophages against the four major MDR Gram-negative pathogens, Klebsiella pneumoniae, Acinetobacter baumannii complex, Pseudomonas aeruginosa, and Escherichia coli, specific data on in vivo PKs (tissue distribution, route of administration, and basic PK parameters in animals and humans) and PDs (survival and reduction of bacterial burden in relation to the route of administration, timing of therapy, dosing regimens, and resistance) are summarized. Currently available data merit close scrutiny, and optimization of bacteriophage therapy in the context of a better understanding of the underlying PK/PD principles is urgent to improve its therapeutic effect and to minimize the occurrence of bacteriophage resistance.

Metabolic and Pharmacokinetic Profiling Studies of N, N-Dimethylaniline-Heliamine in Rats by UHPLC-Q-Orbitrap MS/MS.

Cardiovascular disease is the first cause of death worldwide and kills more people each year than any other cause of death. N, N-dimethylaniline-heliamine (DH), a synthetic tetrahydroisoquinoline alkaloid, has shown notable antiarrhythmic activity. However, the metabolic processes and pharmacokinetic characteristics of DH in rats have not been studied. This study aims to identify its metabolites, as well as develop and validate a rapid and efficient bioanalytical method for quantifying DH in rat plasma over a wide range of concentrations. Its metabolites were characterized in silico, in vitro, and in vivo. A series of 16 metabolites were identified, of which 12 were phase I metabolites and 4 were phase II metabolites. A low probability of DH binding to DNA, protein, and glutathione is predicted by the in silico model. The main metabolic processes of DH were demethylation, dehydrogenation, glucuronidation, and sulfation. Concentration-time profiles were generated by analyzing the plasma, and the outcomes were analyzed via non-compartmental analysis to identify the pharmacokinetic parameters. Among the detected parameters were the volume of distribution, estimated at 126,728.09 ± 56,867.09 mL/kg, clearance at 30,148.65 ± 15,354.27 mL/h/kg, and absolute oral bioavailability at 16.11%. The plasma distribution volume of DH was substantially higher than the overall plasma volume of rats, which suggests that DH has a specific tissue distribution in rats. This study suggests that DH is appropriately bioavailable and excreted via a variety of routes and has low toxicity.

The role of cystathionine β-synthase in cancer

Cysteine β-synthase (CBS) occupies a key position as the initiating enzyme and rate-limiting enzyme in the sulfur transfer pathway and plays a vital role in the health and disease of mammals. CBS is responsible for regulating the metabolism of cysteine, the precursor of glutathione (GSH), an important antioxidant in the body. Additionally, CBS is one of the three enzymes that produce hydrogen sulfide (H2S) in mammals through a variety of mechanisms. The dysregulation of CBS expression in cancer cells affects H2S production through direct or indirect pathways, thereby influencing cancer growth and metastasis by inducing angiogenesis, facilitating proliferation, migration, and invasion, modulating cellular energy metabolism, promoting cell cycle progression, and inhibiting apoptosis. It is noteworthy that CBS expression exhibits complex changes in different cancer models. In this paper, we focus on the CBS synthesis and metabolism, tissue distribution, potential mechanisms influencing tumor growth, and relevant signaling pathways. We also discuss the impact of pharmacological CBS inhibitors and silencing CBS in preclinical cancer models, supporting their potential as targeted cancer therapies.

NLRP3 inflammasome activation and macrophage distribution in kidney tissues from patients with acute oxalate nephropathy.

The current study was initiated to evaluate renal nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome pathway activation and macrophage subtype distribution and their clinicopathological significance in a cohort of oxalate-induced acute kidney injury. Twelve patients with biopsy-proven acute oxalate nephropathy (AON) from January 2016 to October 2022 were retrospectively enrolled, with estimated glomerular filtration rate (eGFR)-matched 24 patients with acute tubulointerstitial nephritis (ATIN) as disease control. Pathological lesions as well as markers of NLRP3 inflammasome pathway and macrophage phenotype detected by immunohistochemistry staining were semi-quantitatively analyzed. Oxalate depositions were found in 5% to 20% of tubules with a positive correlation with Sirius Red staining in AON specimens (rp = 0.668, p = 0.02). Disruption of tubular basement membrane and inflammatory cell reaction was more prominent in specimens of AON (both p < 0.05) as compared with ATIN specimens. The expressions of NLRP3, caspase-1, and gasdermin D were significantly increased in AON specimens as well (all p < 0.05). Patients with M1/M2 macrophage ratio <1 were found with more chronic tubulointerstitial lesions and presented with lower eGFR at the last follow-up (24.8  10.6 mL/min/1.73 m2 vs. 55.1  21.2 mL/min/1.73 m2, p = 0.02) in the AON group. The NLRP3 inflammasome pathway was activated in the kidneys of AON patients, and the ratio of M1 and M2 macrophages was associated with chronicity of pathological changes, which needs further exploration.

The metabolic profiles of endogenous and exogenous substances in a poor metabolizer of humanized CYP2D6 model

Background: Species differences in CYP2D6 drug metabolism complicate the extrapolation of in vivo pharmacokinetic data to humans and impact the prediction of drug responses. This study aimed to develop an in vivo model to predict human responses to CYP2D6 metabolized compounds and to evaluate medication risks and disease development.Methods: We used embryonic stem cell (ES) targeting and CRISPR-Cas9 technology to create a humanized CYP2D6 mouse model by inserting the human wild-type CYP2D6 gene and knocking out the mouse Cyp2d locus. Metoprolol was used as the substrate probe to examine the pharmacokinetic properties of exogenous substances, tissue distribution, and in situ metabolism of CYP2D6. Untargeted and quantitative metabolomics analyses compared endogenous substance metabolism between different species of CYP2D6 enzymes.Results: No significant differences in CYP2D6 homologous protein distribution and expression of primary metabolic organs were found between humanized CYP2D6 mice and wild-type (WT) mice. The activity and metabolic capacity of CYP2D6 in humanized mice were substantially lower than homologous Cyp2d22 of WT mice in metabolizing metoprolol. The levels of several glycerolipids and glycerophospholipid-related metabolites were down-regulated in humanized CYP2D6 mice. Triglyceride TG (14:0_22:6_22:6) was significantly downregulated in male and female humanized mice, suggesting a strong association with reduced CYP2D6 activity.Conclusions: This study established a robust animal model to investigate human CYP2D6-mediated metabolic profiles of exogenous and endogenous compounds, predict medication risks, and explore the potential roles of CYP2D6 in organ-specific toxicity and disease development.

Model order reduction and sensitivity analysis for complex heat transfer simulations inside the human eyeball.

Heat transfer in the human eyeball, a complex organ, is significantly influenced by various pathophysiological and external parameters. Particularly, heat transfer critically affects fluid behavior within the eye and ocular drug delivery processes. Overcoming the challenges of experimental analysis, this study introduces a comprehensive three-dimensional mathematical and computational model to simulate the heat transfer in a realistic geometry. Our work includes an extensive sensitivity analysis to address uncertainties and delineate the impact of different variables on heat distribution in ocular tissues. To manage the model's complexity, we employed a very fast model reduction technique with certified sharp error bounds, ensuring computational efficiency without compromising accuracy. Our results demonstrate remarkable consistency with experimental observations and align closely with existing numerical findings in the literature. Crucially, our findings underscore the significant role of blood flow and environmental conditions, particularly in the eye's internal tissues. Clinically, this model offers a promising tool for examining the temperature-related effects of various therapeutic interventions on the eye. Such insights are invaluable for optimizing treatment strategies in ophthalmology.

Evolution of chitin-synthase in molluscs and their response to ocean acidification

Chitin-synthase (CHS) is found in most eukaryotes and has a complex evolutionary history. Research into CHS has mainly been in the context of biomineralization of mollusc shells an area of high interest due to the consequences of ocean acidification. Exploration of CHS at the genomic level in molluscs, the evolution of isoforms, their tissue distribution, and response to environmental challenges are largely unknown. Exploiting the extensive molecular resources for mollusc species it is revealed that bivalves possess the largest number of CHS genes (12–22) reported to date in eukaryotes. The evolutionary tree constructed at the class level of molluscs indicates four CHS Type II isoforms (A-D) probably existed in the most recent common ancestor, and Type II-A (Type II-A-1/Type II-A-2) and Type II-C (Type II-C-1/Type II-C-2) underwent further differentiation. Non-specific loss of CHS isoforms occurred at the class level, and in some Type II (B-D groups) isoforms the myosin head domain, which is associated with shell formation, was not preserved and highly species-specific tissue expression of CHS isoforms occurred. These observations strongly support the idea of CHS functional diversification with shell biomineralization being one of several important functions. Analysis of transcriptome data uncovered the species-specific potential of CHS isoforms in shell formation and a species-specific response to ocean acidification (OA). The impact of OA was not CHS isoform-dependent although in Mytilus, Type I-B and Type II-D gene expression was down-regulated in both M. galloprovincialis and M. coruscus. In summary, during CHS evolution the gene family expanded in bivalves generating a large diversity of isoforms with different structures and with a ubiquitous tissue distribution suggesting that chitin is involved in many biological functions. These findings provide insight into CHS evolution in molluscs and lay the foundation for research into their function and response to environmental changes.

In silico assessments of the small molecular boron agents to pave the way for artificial intelligence-based boron neutron capture therapy

Boron neutron capture therapy (BNCT) is a highly targeted, selective and effective technique to cure various types of cancers, with less harm to the healthy cells. In principle, BNCT treatment needs to distribute the 10boron (10B) atoms inside the tumor tissues, selectively and homogeneously, as well as to initiate a nuclear fission reaction by capturing sufficient neutrons which releases high linear energy particles to kill the tumor cells. In BNCT, it is crucial to have high quality boron agents with acceptable bio-selectivity, homogeneous distribution and deliver in required quantity, similar to chemotherapy and other radiotherapy for tumor treatment. Nevertheless, boron drugs currently used in clinical trials yet to meet the full requirements. On the other hand, BNCT processing has opened up the era of renaissance due to the advanced development of the high-quality neutron source and the global construction of new BNCT centers. Consequently, there is an urgent need to use boron agents that have increased biocapacity. Artificial intelligence (AI) tools such as molecular docking and molecular dynamic simulation technologies have been utilized to develop new medicines. In this work, the in silico assessments including bioinformatics assessments of BNCT related tumoral receptor proteins, computational assessments of optimized small molecules of boron agents, are employed to speed up the screening process for boron drugs. The outcomes will be applicable to pave the way for future BNCT that utilizes artificial intelligence. The in silico molecular docking and dynamic simulation results of the optimized small boron agents, such as 4-borono-l-phenylalanine (BPA) with optimized proteins like the L-type amino acid transporter 1 (LTA1, also known as SLC7A5) will be examined. The in silico assessments results will certainly be helpful to researchers in optimizing druggable boron agents for the BNCT application. The clinical status of the optimized proteins, which are highly relevant to cancers that may be treated with BNCT, has been assessed using bioinformatics technology and discussed accordingly. Furthermore, the evaluations of cytotoxicity (IC50), boron uptake and tissue distribution of the optimized ligands 1 and 7 have been presented.

The assessment of pharmacokinetics and neuroprotective effect of berberine hydrochloride-embedded albumin nanoparticles via various administration routes: comparative in-vivo studies in rats.

The current study aimed to evaluate the pharmacokinetics and neuroprotective effect of well-characterised berberine-bovine serum albumin (BBR-BSA) nanoparticles. BBR-BSA nanoparticles were generated by desolvation method. Entrapment efficiency, loading capacity, particle size, polydispersity index, surface morphology, thermal stability, and in-vitro release were estimated. In-vitro pharmacokinetic and tissue distribution were conducted. Their neuroprotection was evaluated against lipopolysaccharides-induced neurodegeneration. BBR-BSA nanoparticles showed satisfactory particle size (202.60 ± 1.20 nm) and entrapment efficiency (57.00 ± 1.56%). Results confirmed the formation of spheroid-thermal stable nanoparticles with a sustained drug release over 48 h. Sublingual and intranasal routes had higher pharmacokinetic plasma profiles than other routes, with Cmax values at 0.75 h (444 ± 77.79 and 259 ± 42.41 ng/mL, respectively). BBR and its metabolite distribution in the liver and kidney were higher than in plasma. Intranasal and sublingual treatment improves antioxidants, proinflammatory, amyloidogenic biomarkers, and brain architecture, protecting the brain. In conclusion, neuroinflammation and neurodegeneration may be prevented by intranasal and sublingual BBR-BSA nanoparticles.

Cell-penetrating peptides TAT and 8R functionalize P22 virus-like particles to enhance tissue distribution and retention in vivo.

Virus-like particles (VLPs) are used as nanocontainers for targeted drug, protein, and vaccine delivery. The phage P22 VLP is an ideal macromolecule delivery vehicle, as it has a large exterior surface area, which facilitates multivalent genetic and chemical modifications for cell recognition and penetration. Arginine-rich cell-penetrating peptides (CPPs) can increase cargo transport efficiency in vivo. However, studies on the tissue distribution and retention of P22 VLPs mediated by TAT and 8R are lacking. This study aimed to analyze the TAT and 8R effects on the P22 VLPs transport efficiency and tissue distribution both in vitro and in vivo. We used a prokaryotic system to prepare P22 VLP self-assembled particles and expressed TAT-or 8R-conjugated mCherry on the VLP capsid protein as model cargoes and revealed that the level of P22 VLP-mCherry penetrating the cell membrane was low. However, both TAT and 8R significantly promoted the cellular uptake efficiency of P22 VLPs in vitro, as well as enhanced the tissue accumulation and retention of P22 VLPs in vivo. At 24 h postinjection, TAT enhanced the tissue distribution and retention in the lung, whereas 8R could be better accumulation in brain. Thus, TAT was superior in terms of cellular uptake and tissue accumulation in the P22 VLPs delivery system. Understanding CPP biocompatibility and tissue retention will expand their potential applications in macromolecular cargo delivery.

Characterization and In vitro Release & In vivo Behavior Study of Self-Assembled Nano-Emulsion in XiaoYao Pill for Enhanced Drug Delivery.

Traditional Chinese medicine formulations often contain hydrophobic components with limited solubility and stability, leading to low oral bioavailability. Self-assembled nanoparticles (SANs) have shown promise in enhancing oral bioavailability of these components. However, whether un-decocted Chinese herbal pellets can generate SANs and the impact of SANs formed by multiple components on pharmacokinetic parameters remains unexplored. In this study, single-factor approach was employed to determine the optimal separation method of nano-emulsion phase of XiaoYao pill (N-XY). Morphological and particle size analyses confirmed the nanoscale nature of N-XY. High-performance liquid chromatography (HPLC) fingerprint analysis was conducted to compare the distribution of active ingredients among three different phases of XiaoYao pill (XY pill). In vitro release studies were performed to evaluate the release mechanism of four ingredients from N-XY. Additionally, in vivo pharmacokinetics and tissue distribution behaviors were investigated in rats. N-XY exhibited uniform and stable characteristics as a water-in-oil (O/W) nano-emulsion. Fingerprint analysis identified 25 characteristic peaks and 8 key ingredients in N-XY, with the highest peak areas. In vitro release studies showed a sustained release behavior of N-XY. The pharmacokinetics study showed that the ferulic acid of N-XY had a 1.37-fold higher AUC, 1.44-fold lower Vd/F, 1.39-fold lower CL/F, and a prolonged t1/2 than A-XY, indicating enhanced bioavailability due to reduced elimination. Furthermore, the tissue distribution revealed that the levels of paeoniflorin and ferulic acid from N-XY significantly increased in liver, spleen, lungs, uterus and ovaries, exhibiting targeting characteristics. This study comprehensively explored the formation, characterization, and pharmacokinetics of nano-emulsion in XY pill, introducing novel perspectives and initiating preliminary research on potential SANs in un-decocted traditional Chinese medicine formulations. It also emphasized the importance of enhancing pharmacokinetics of hydrophobic components in Chinese herbal formulations and laid the foundation for future nano-formulation research for XY pill.

Metabolic benefits afforded by estradiol and testosterone in both sexes: clinical considerations.

Testosterone (T) and 17β-estradiol (E2) are produced in male and female humans and are potent metabolic regulators in both sexes. When E2 and T production stops or decreases during aging, metabolic dysfunction develops and promotes degenerative metabolic and vascular disease. Here, we discuss the shared benefits afforded by E2 and T for metabolic function human females and males. In females, E2 is central to bone and vascular health, subcutaneous adipose tissue distribution, skeletal muscle insulin sensitivity, antiinflammatory immune function, and mitochondrial health. However, T also plays a role in female skeletal, vascular, and metabolic health. In males, T's conversion to E2 is fundamental to bone and vascular health, as well as prevention of excess visceral adiposity and the promotion of insulin sensitivity via activation of the estrogen receptors. However, T and its metabolite dihydrotestosterone also prevent excess visceral adiposity and promote skeletal muscle growth and insulin sensitivity via activation of the androgen receptor. In conclusion, T and E2 are produced in both sexes at sex-specific concentrations and provide similar and potent metabolic benefits. Optimizing levels of both hormones may be beneficial to protect patients from cardiometabolic disease and frailty during aging, which requires further study.

Molecular evidence of hepatozoonosis in tigers of Vidarbha region of Maharashtra State of India

BackgroundHepatozoonosis has been reported in many species around the world. Few incidences have been reported in various species of wild felids. Tigers are endangered large cats and are protected under the Wildlife Protection Act, 1972 under Schedule I. The study was carried out to estimate the positivity rate of hepatozoonosis in tigers of the Vidarbha region of Maharashtra, India.MethodsBlood (n = 21) or tissue samples (n = 5) were collected from 26 wild captured / zoo-born or dead tigers during the quarantine period/post-mortem examination. Blood smear examination along with Polymerase Chain Reaction (PCR) studies were conducted for the detection of hepatozoonosis. All the amplicons from the positive samples were purified and sequenced, and the sequences were subjected to nBLAST analysis to detect the species of Hepatozoon. The sequences were deposited into public domain database of National Center for Biotechnology Information (NCBI) and accession numbers were allotted. A phylogenetic study was undertaken to understand the evolutionary lineage of the pathogen. Tissue distribution studies were carried out on tissue samples received during post mortem. A clinical case in a tiger cub was managed and sub-clinical cases were monitored for relapse. Age-wise, sex-wise, region-wise and captive time-wise positivity rate was estimated. The data was analyzed using statistical tools.ResultsA total of 12 tigers were found positive for H. felis during the screening. A clinical case was diagnosed and successfully treated. The age group of 0–3 years reported a positivity rate of 66.66%, and all the cases found positive were reported between the age group of 0–7 years. Males reported a positivity rate of 58.33 per cent, while females reported 35.71%. Taboba and Andhari Tiger Reserve of the state had a positivity rate of 52.94 per cent. However, the statistical analysis for blood parameters and positivity rate by ‘t’ test and Chi-squared test were found to be non-significant.ConclusionsAn overall positivity rate of 46.15% indicates the wide distribution of hepatozoonosis among wild tigers of the Vidarbha region of Maharashtra, India, which is strategically important considering the gene flow and migration of tigers. Hepatozoonosis can progress to clinical outcomes in young animals and require veterinary intervention. Molecular tools and phylogenetic studies can supplement important data on circulating species of Hepatozoon in the field. Further studies on the clinical management and epidemiology of the infection in wild felids will comprehend the cause of wildlife conservation.

Excess Folic Acid Exposure Increases Uracil Misincorporation into DNA in a Tissue-Specific Manner in a Mouse Model of Reduced Methionine Synthase Expression

BackgroundFolate and vitamin B12 (B12) are cofactors in folate-mediated 1-carbon metabolism (FOCM), a metabolic network that supports synthesis of nucleotides (including thymidylate [dTMP]) and methionine. FOCM impairments such as a deficiency or imbalance of cofactors can perturb dTMP synthesis, causing uracil misincorporation into DNA. ObjectiveThe purpose of this study was to determine how reduced expression of the B12-dependent enzyme methionine synthase (MTR) and excess dietary folic acid interact to affect folate distribution and markers of genome stability in mouse tissues. MethodsHeterozygous Mtr knockout mice (Mtr+/–) model the FOCM-specific effects of B12 deficiency. Folate accumulation and vitamer distribution, genomic uracil concentrations, and phosphorylated histone H2AX (γH2AX) immunostaining were measured in male Mtr+/+ and Mtr+/− mice weaned to either a folate-sufficient control (C) diet (2 mg/kg folic acid) or a high folic acid (HFA) diet (20 mg/kg folic acid) for 7 wk. ResultsExposure to the HFA diet led to tissue-specific patterns of folate accumulation, with plasma, colon, kidney, and skeletal muscle exhibiting increased folate concentrations compared with control. Liver total folate did not differ. Although unmetabolized folic acid (UMFA) increased 10-fold in mouse plasma with HFA diet, UMFA accounted for <0.2% of total folate in liver and colon tissue. Exposure to HFA diet resulted in a shift in folate distribution in colon tissue with higher 5-methyl-THF and lower formyl-THF than in control mice. Mtr heterozygosity did not impact folate accumulation or distribution in any tissue. Mice on HFA diet exhibited higher uracil in genomic DNA and γH2AX foci in colon. Similar differences were not seen in liver. ConclusionsThis study demonstrates that folic acid, even when consumed at high doses, does not meaningfully accumulate in mouse tissues, although high-dose folic acid shifts folate distribution and increases uracil accumulation in genomic DNA in colon tissue.

Numerical simulation in magnetic resonance imaging radiofrequency dosimetry

Magnetic Resonance Imaging (MRI) employs a radiofrequency electromagnetic field to create pictures on a computer. The prospective biological consequences of exposure to radiofrequency electromagnetic fields (RF EMFs) have not yet been demonstrated, and there is not enough evidence on biological hazards to offer a definite response concerning possible RF health dangers. Therefore, it is crucial to research the health concerns in reaction to RF EMFs, considering the entire exposure in terms of patients receiving MRI. Monitoring increases in temperature in-vivo throughout MRI scan is extremely invasive and has resulted in a rise in the utilization of computational methods to estimate distributions of temperatures. The purpose of this study is to estimate the absorbed power of the brain exposed to RF in patients undergoing brain MRI scan. A three-dimensional Penne’s bio-heat equation was modified to computationally analyze the temperature distributions and potential thermal effects within the brain during MRI scans in the 0.3 T to 1.5 T range (12.77 MHz to 63.87 MHz). The instantaneous temperature distributions of the in-vivo tissue in the brain temperatures measured at a time, t = 20.62 s is 0.2 °C and t = 30.92 s is 0.4 °C, while the highest temperatures recorded at 1.03 min and 2.06 min were 0.4 °C and 0.6 °C accordingly. From the temperature distributions of the in-vivo tissue in the brain temperatures measured, there is heat build-up in patients who are exposed to electromagnetic frequency ranges, and, consequently, temperature increases within patients are difficult to prevent. The study has, however, indicated that lengthier imaging duration appears to be related to increasing body temperature.

A physiologically based toxicokinetic model for microplastics and nanoplastics in mice after oral exposure and its implications for human dietary exposure assessment

Evidence of microplastics (MPs) and nanoplastics (NPs) in foods and daily-use products, along with their frequent detection in the human body, has raised concerns regarding their potential impact on human health through dietary ingestion. However, there is a lack of quantitative tools to simulate their bioaccumulation and tissue distribution following environmental exposure. To address this gap, we developed the first physiologically based toxicokinetic (PBTK) model for predicting the biodistribution of MPs and NPs in mice following oral exposure under various exposure scenarios. This novel model incorporated key kinetic mass transport processes, such as membrane permeability, albumin binding, and cellular uptake. We identified that the absorption rate in the gastrointestinal tract and fecal excretion rate constant had significant impacts on organ dosimetry. Our regression analysis indicated that the size-dependent dissociation constant and urine clearance rate constant sharply increased by a factor of 3 as NPs particle size increased to 1µm. Finally, we developed a graphical user interface to enable interactive visualization and analysis for future applications, supporting human dietary exposure and risk assessment using available food consumption data and MPs/NPs residue data. The simulation results offer a mechanistic perspective, enhancing understanding of the internal organ dosimetry burden and health impacts from dietary exposure to MPs and NPs.