A review of monoamine oxidase (MAO) inhibitors in tobacco or tobacco smoke

Tobacco smoking is reputed to be the most difficult addiction of all to give up, and nicotine has been noted as the major addictive agent in tobacco smoke. However, research shows that nicotine addiction is due to more than nicotine alone. One hypothesis is that monoamine oxidase (MAO) inhibition from non-nicotinic components in, or derived from, tobacco smoke contributes to nicotine addiction. Harman and norharman, have been recognised as major and potent MAO inhibitors in tobacco smoke, but these two inhibitors together comprise perhaps less than 10% of the total MAO A inhibitory activity in cigarette smoke suggesting other unidentified components may make significant contributions to total inhibitory activity. Therefore, we reviewed an index of the chemical components of tobacco and tobacco smoke and identified those known to be MAO inhibitors. Amongst these inhibitors, phenols and phenolic acids with MAO inhibitory activity are commonly reversible and selective MAO A inhibitors, whereas trans,trans-farnesol, 2-methyl-1,4-naphthoquinone (menadione), 1,4-naphthoquinone, scopoletin, and diosmetin with MAO inhibitory activity are reversible and selective MAO B inhibitors. The compound, 1,4-benzoquinone is an irreversible MAO A inhibitor and to the best of our knowledge, this is the first irreversible MAO A inhibitor to be reported in tobacco smoke. MAO inhibitors have been used clinically to treat depression, anxiety, and Parkinson's disease. The MAO inhibitors identified from tobacco and tobacco smoke and summarized in this review, are potential pharmacological candidates to be investigated further. This review will enhance our knowledge of the way tobacco smoke affects MAO activity in smokers and will also be important in helping to understand nicotine addiction.

A cross-sectional study of the relationship between recreational sporting activity and calcaneal bone density in adolescents and young adults

OBJECTIVE

Childhood and adolescence are critical periods of bone development. Sporting activity is thought to impact peak bone mass acquisition, but most studies have used dual-energy X-ray absorptiometry (DXA) to assess bone health and reported associations between bone mass and elite sporting activity. The objective of this study was instead to assess the relationship between recreational sporting activity (RSA) and another bone assessment, calcaneal quantitative ultrasound (cQUS), in adolescents and young adults.

METHODS

We related recreational sporting activity, assessed through a lifestyle questionnaire, to heel ultrasound bone parameters in a cohort of New Zealand students aged 16-35 years. Complete datasets with data on all relevant confounders (body mass index (BMI), pubertal timing, smoking status, and alcohol consumption) were available for 452 participants. cQUS was performed using a Lunar Achilles EX II machine to obtain bone parameters, broadband ultrasound attenuation (BUA), and speed of sound (SOS); stiffness index (SI) was derived from these measures. All descriptive statistics and statistical analyses were carried out using SPSS Statistics for Macintosh, Version 23.0 (IBM Corp., Armonk, NY, USA). Results are presented as p-values and 95% CI.

RESULTS

Reported lifetime sport participation declined after an individual's mid-teens. Bone cQUS parameters (SI and BUA and T-score) were all positively associated with BMI, and current physical activity (SI, SOS, BUA, T-score, and Z-score) with SI and SOS measures most strongly associated with current high impact and past recreational sporting activity (all p < 0.05).

CONCLUSION

Calcaneal heel ultrasound bone parameters were associated with physical activity, with SI and SOS rather than BUA more strongly related to current and past recreational sporting activity in young New Zealand adults.

Biologically Active Compounds Present in Tobacco Smoke: Potential Interactions Between Smoking and Mental Health

Tobacco dependence remains one of the major preventable causes of premature morbidity and mortality worldwide. There are well over 8,000 compounds present in tobacco and tobacco smoke, but we do not know what effect, if any, many of them have on smokers. Major interest has been on nicotine, as well as on toxic and carcinogenic effects and several major and minor components of tobacco smoke responsible for the negative health effects of smoking have been elucidated. Smokers themselves report a variety of positive effects from smoking, including effects on depression, anxiety and mental acuity. Smoking has also been shown to have protective effects in Parkinson’s Disease. Are the subjective reports of a positive effect of smoking due to nicotine, of some other components of tobacco smoke, or are they a manifestation of the relief from nicotine withdrawal symptoms that smoking provides? This mini-review summarises what is currently known about the components of tobacco smoke with potential to have positive effects on smokers.

Isolation, characterisation and detection of breath-derived extracellular vesicles

The physical characterisation, capture and detection of extracellular vesicles (EVs) and exosomes derived from breath condensate is reported. Breath-derived EVs were isolated from breath condensate and captured on a gold substrate using two complimentary methods. The characterised and isolated EVs were detected using surface plasmon resonance (SPR) and electrochemical impedance spectroscopy (EIS). EIS was done using aptamers as a targeting moiety and showed a larger change in resistance between dilute concentrations of EVs (less than 7 μg/mL).This is the first report of EVs and exosomes isolated and characterised from breath. In addition, EVs from a non-invasive and easily available source such as breath opens up further avenues in the detection of pulmonary diseases.

The Relationship Between Non-elite Sporting Activity and Calcaneal Bone Density in Adolescents and Young Adults: A Narrative Systematic Review

Introduction: Osteoporotic fractures represent a major public health burden. The risk of fragility fractures in late adulthood is strongly impacted by peak bone mass acquisition by the third decade. Weight-bearing sporting activity may be beneficial to peak bone mass accrual, but previous studies have focused on elite sporting activity and have used dual energy X-ray absorptiometry as a measure of bone density. The authors performed a narrative systematic review of individual sports (performed non-competitively or at local level) and calcaneal quantitative ultrasound (cQUS) bone measures in young people.

Methods: Multiple databases were systematically searched up until the 31st of March 2019. The authors included studies of participants' mean age (11–35 years), reporting any level of recreational sporting activity and cQUS measures as well as excluding elite/professional sporting physical activity. Studies (title and abstract) were screened independently by two reviewers, and a third reviewer resolved any discrepancies. STROBE guidelines were used to check the reporting of observational studies. The Newcastle–Ottawa Scale was used to assess the risk of bias of the studies included in the review. The systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO).

Results: A search yielded 29,512 articles that considered relationships between bone density assessed by any technique and sporting activity. Duplicate and out of scope abstracts were removed. This left 424 papers that were screened by two reviewers; of these, six met the inclusion criteria, including assessment by cQUS. The authors identified papers where sports were considered, included soccer (football), swimming, cycling, gymnastics, dancing, badminton, basketball, fencing, wrestling, and judokas. Although study heterogeneity prohibited meta-analysis, all six included studies reported significant benefits of weight-bearing non-elite sports on cQUS outcomes.

Conclusion: Our study found beneficial effects of non-elite sports participation on cQUS in adolescence and young adulthood, although further work is now indicated.

A qualitative examination of the GST proteome of the blow fly, Lucilia cuprina: use of cross-database matching of MALDI data

This study was aimed at determining whether, in the absence of a full genetic database for the Sheep Blowfly (Lucilia cuprina) glutathione transferases from this insect could be characterized by cross-database matching of MALDI TOF data with the database for other metazoan organisms. Glutathione transferases of L. cuprina were partially purified by the sequential use of affinity chromatography media; first on glutathione immobilized on epichlorohydrin-activated Sepharose 6B and subsequently on dinitrophenyl-glutathione immobilized on the same matrix. The Proteins obtained were separated by 2D SDS-PAGE and tentatively characterized by MALDI-TOF analysis of tryptic peptides. The mass fragments were matched against the NCBInr "Other metazoa" database. The GSTs matched to other insect species were identified as coming from the Sigma, Delta and Epsilon classes. The relative abundance of most of these GSTs appeared to vary little during development, or across bodily segments, an exception being one group, (Zone E) tentatively identified as Epsilon class, which was most prominent in eggs and absent from adults and which is therefore assumed to play a specific role in development.

Structure-activity studies of the pelorusides: new congeners and semi-synthetic analogues

Two new peloruside congeners (3 and 4) were isolated from wild and aquacultured collections of the New Zealand marine sponge Mycale hentscheli. Small-scale reactions on peloruside A (1) have been performed, which along with the isolation of 3 and 4, give further insight into the bioactive pharmacophore of 1.

Development of Nonsymmetrical 1,4-Disubstituted Anthraquinones That Are Potently Active against Cisplatin-Resistant Ovarian Cancer Cells

A novel series of 1,4-disubstituted aminoanthraquinones were prepared by ipso-displacement of 1,4-difluoro-5,8-dihydroxyanthraquinones by hydroxylated piperidinyl- or pyrrolidinylalkylamino side chains. One aminoanthraquinone (13) was further derivatized to a chloropropylamino analogue by treatment with triphenylphosphine-carbon tetrachloride. The compounds were evaluated in the A2780 ovarian cancer cell line and its cisplatin-resistant variants (A2780/cp70 and A2780/MCP1). The novel anthraquinones were shown to possess up to 5-fold increased potency against the cisplatin-resistant cells compared to the wild-type cells. Growth curve analysis of the hydroxyethylaminoanthraquinone 8 in the osteosarcoma cell line U-2 OS showed that the cell cycle is not frozen, rather there is a late cell cycle arrest consistent with the action of a DNA-damaging topoisomerase II inhibitor. Accumulative apoptotic events, using time lapse photography, indicate that 8 is capable of fully engaging cell cycle arrest pathways in G2 in the absence of early apoptotic commitment. 8 and its chloropropyl analogue 13 retained significant activity against human A2780/cp70 xenografted tumors in mice.

Stimulation of mammalian translation initiation factor eIF4A activity by a small molecule inhibitor of eukaryotic translation

RNA helicases are the largest group of enzymes in eukaryotic RNA metabolism. The DEXD/H-box putative RNA helicases form the helicase superfamily II, whose members are defined by seven highly conserved amino acid motifs, making specific targeting of selected members a challenging pharmacological problem. The translation initiation factor eIF4A is the prototypical DEAD-box RNA helicase that works in conjunction with eIF4B and eIF4H and as a subunit of eIF4F to prepare the mRNA template for ribosome binding, possibly by unwinding the secondary structure proximal to the 5' m7GpppN cap structure. We report the identification and characterization of a small molecule inhibitor of eukaryotic translation initiation that acts in an unusual manner by stimulating eIF4A-associated activities. Our results suggest that proper control of eIF4A helicase activity is necessary for efficient ribosome binding and demonstrate the feasibility of selectively targeting DEAD-box RNA helicases with small molecules.

Peloruside A does not bind to the taxoid site on beta-tubulin and retains its activity in multidrug-resistant cell lines

Peloruside A (peloruside), a microtubule-stabilizing agent from a marine sponge, is less susceptible than paclitaxel to multidrug resistance arising from overexpression of the P-glycoprotein efflux pump and is not affected by mutations that affect the taxoid binding site of beta-tubulin. In vitro studies with purified tubulin indicate that peloruside directly induces tubulin polymerization in the absence of microtubule-associated proteins. Competition for binding between peloruside, paclitaxel, and laulimalide revealed that peloruside binds to a different site on tubulin to paclitaxel. Moreover, laulimalide was able to displace peloruside, indicating that peloruside and laulimalide may compete for the same or overlapping binding sites. It was concluded that peloruside and laulimalide have binding properties that are distinct from other microtubule-stabilizing compounds currently under investigation.

Binding of hematin by a new class of glutathione transferase from the blood-feeding parasitic nematode Haemonchus contortus

The phase II detoxification system glutathione transferase (GST) is associated with the establishment of parasitic nematode infections within the gastrointestinal environment of the mammalian host. We report the functional analysis of a GST from an important worldwide parasitic nematode of small ruminants, Haemonchus contortus. This GST shows limited activity with a range of classical GST substrates but effectively binds hematin. The high-affinity binding site for hematin was not present in the GST showing the most identity, CE07055 from the free-living nematode Caenorhabditis elegans. This finding suggests that the high-affinity binding of hematin may represent a parasite adaptation to blood or tissue feeding from the host.

Microtubule stress modifies intra-nuclear location of Msh2 in mouse embryonic fibroblasts

The maintenance of genomic stability in mitotic and meiotic cycles through mismatch repair (MMR) demands the coordination of MMR functions with multiple processes including cell cycle traverse, linked changes in microtubule dynamics, protein translocation at chromatin sites and checkpoint activation. We have studied changes in the intracellular location of the MMR protein Msh2 in response to mitosis, microtubule disruption by colcemid and DNA damage induction by cis-platin in mouse embryonic fibroblasts (MEFs). Image analysis indicated that MEFs have a normally high nuclear retention of Msh2 during interphase with a precipitous dispersal of protein from chromatin sites into the cytoplasm at mitosis. Dispersal was also observed in cisplatin- and colcemid-treated interphase MEFs without any change in the overall Msh2 levels throughout the cell cycle. There was no evidence of co-localization of the punctate cytoplasmic Msh2 foci with any microtubule structures and knockout of Msh2 altered neither the extent of microtubule disruption nor the functional activation of the spindle assembly checkpoint by colcemid. Critically, extra-nuclear relocation of protein did not alter the ability to mount an Msh2-dependent G2 checkpoint delay in response to cisplatin-induced DNA damage. Depletion of the nuclear pool of Msh2 protein in cells undergoing dispersal was found to involve a rapid relocation of protein from AT-rich chromatin sites as defined by coassociation studies exploiting a newly-characterized base-pair preference of the fluorescent DNA binding probe DRAQ5. The study reveals the unexpected mobility of MMR protein pools during the MEF cell cycle and in response to different stress-inducing agents. The results link for the first time microtubule-integrity with intra-nuclear Msh2 protein dynamics. The high nuclear retention of Msh2 in interphase MEFs is in contrast to human tumor cells while the observations on protein dispersal suggest that only low levels of nuclear-located Msh2 are needed for G2 checkpoint activation by DNA damage.

Alchemix: a novel alkylating anthraquinone with potent activity against anthracycline- and cisplatin-resistant ovarian cancer

Chloroethylaminoanthraquinones are described with intercalating and alkylating capacity that potentially covalently cross-link topoisomerase II (topo II) to DNA. These compounds have potent cytotoxic activity (IC(50) = 0.9-7.6 nM) against the A2780 human ovarian carcinoma cell line. Hydroxyethylaminoanthraquinones also reported in this paper have similar IC(50) values (0.7-1.7 nM) in the same cell line. Alchemix (ZP281M, 1-(2-[N,N-bis(2-chloroethyl)amino]ethylamino)-4-(2-[N,N-(dimethyl)amino]ethylamino)-5,8-dihydroxy-9,10-anthracenedione), an alkylating anthraquinone, retains excellent antitumor activity in Adriamycin-resistant (2780AD) and cisplatin-resistant (2780/cp70) cell lines in vitro and in vivo. This indicates that Alchemix can evade both P-glycoprotein efflux pump and DNA mismatch repair-mediated resistance. In treated cells, Alchemix was shown to preferentially induce drug-stabilized covalent bound topo IIalpha-DNA complexes over topo IIbeta-DNA complexes.

A TSM sensor investigation of low crystallinity cellulose films

A thickness shear mode (TSM) quartz sensor has been used to characterize the substantivity, viscoelasticity, and mucoadhesive properties of low crystallinity cellulose (LCC) films. LCC is a novel pharmaceutical excipient that has been attributed with mucoadhesive properties. Thin films of LCC were deposited onto TSM sensors by a spin coating technique. The films were treated by passing water or 1.0% w/v mucin solution (pH 3.7 or 7.0) over the surface. Changes in the mass and viscosity of the film were observed by monitoring changes in the impedance spectra of the coated TSM sensors. Scanning electron micrographs (SEMs) of each film were used to assist the interpretation of the TSM sensor data. This study showed that LCC forms highly tenacious and viscoelastic films able to withstand prolonged (approximately 1 h) exposure to both water and mucin solution. Furthermore, these results indicate that the films may have mucoadhesive properties as LCC was found to bind significant (P<0.05) amounts of mucin in comparison with control measurements. Mucin binding to the LCC sensor was greater at pH 3.7 (P<0.05) than at pH 7.0, suggesting that the LCC formulation is mucoadhesive under these conditions.

Characteristics of a novel deep red/infrared fluorescent cell-permeant DNA probe, DRAQ5, in intact human cells analyzed by flow cytometry, confocal and multiphoton microscopy

BACKGROUND

The multiparameter fluorometric analysis of intact and fixed cells often requires the use of a nuclear DNA discrimination signal with spectral separation from visible range fluorochromes. We have developed a novel deep red fluorescing bisalkylaminoanthraquinone, DRAQ5 (Ex(lambdamax) 646 nm; Em(lambdamax) 681 nm; Em(lambdarange) 665->800 nm), with high affinity for DNA and a high capacity to enter living cells. We describe here the spectral characteristics and applications of this synthetic compound, particularly in relation to cytometric analysis of the cell cycle.

METHODS

Cultured human tumor cells were examined for the ability to nuclear locate DRAQ5 using single and multiphoton laser scanning microscopy (LSM) and multiparameter flow cytometry.

RESULTS

Multiparameter flow cytometry shows that the dye can rapidly report the cellular DNA content of live and fixed cells at a resolution level adequate for cell cycle analysis and the cycle-specific expression of cellular proteins (e.g., cyclin B1). The preferential excitation of DRAQ5 by laser red lines (633/647 nm) was found to offer a means of fluorescence signal discrimination by selective excitation, with greatly reduced emission overlap with UV-excitable and visible range fluophors as compared with propidium iodide. LSM reveals nuclear architecture and clearly defines chromosomal elements in live cells. DRAQ5 was found to permit multiphoton imaging of nuclei using a 1,047-nm emitting mode-locked YLF laser. The unusual spectral properties of DRAQ5 also permit live cell DNA analysis using conventional 488 nm excitation and the single-photon imaging of nuclear fluorescence using laser excitation between 488 nm and low infrared (IR; 780 nm) wavelengths. Single and multiphoton microscopy studies revealed the ability of DRAQ5 to report three-dimensional nuclear structure and location in live cells expressing endoplasmic reticulum targeted-GFP, MitoTracker-stained mitochondria, or a vital cell probe for free zinc (Zinquin).

CONCLUSION

The fluorescence excitation and emission characteristics of DRAQ5 in living and fixed cells permit the incorporation of the measurement of cellular DNA content into a variety of multiparameter cytometric analyses.

Characterisation of fatty acid multilayers using a TSM biosensor

Thickness shear mode (TSM) biosensors have many potential applications within the pharmaceutical sciences as a means of measuring mass changes in the nanogram range, film thickness, viscosity and shear moduli. This study addresses the possible use of the TSM sensor as a biosensor for measuring drug partition coefficients. In order to realise this potential, some fundamental understanding is required of the behaviour of lipid films on the sensor. The present study characterises the behaviour of fatty acid multilayers as a suitable model chemical system. Frequency shifts and impedance spectra are presented for multilayers of three fatty acid films coated on to the sensor using a Langmuir-Blodgett trough. The results indicate that the frequency shift is non-linear at lower numbers of fatty acid layers but the response is Sauerbrey-like at higher numbers of layers. Also at high numbers of layers, changes in the impedance spectra indicate viscoelastic behaviour in thicker membranes. An inverse relationship is observed between chain length and frequency shift, which is attributed to variations in the topography of the sensor surface. This work demonstrates the importance of fully characterising the physical behaviour of the lipid multilayers prior to using these systems for the measurement of drug partition coefficients.

Structural and functional analysis of a glutathione S-transferase from Ascaris suum

A recombinant glutathione S-transferase (GST) (EC 2.5.1.18) from the parasitic nematode Ascaris suum (AsGST1) displays specific activity with a variety of model substrates and secondary products of lipid peroxidation. The AsGST1 interacts with a range of model inhibitors, haematin-related compounds, bile acids and anthelminthics. The reported variations in biochemical activity correlate with structural differences observed by homology modelling. Here, differences in the topography of the proposed substrate binding site between the AsGST1 and the host GSTs were identified. A rabbit polyclonal antiserum was raised against the glutathione-binding proteins of A. suum and specific antibodies against AsGST1 were affinity-purified using the recombinant protein. These antibodies were used to localize the AsGST1 in adult worms by immunohistochemical staining. The strongest immunostaining for AsGST1 was localized in the intestine in all worms examined. This suggests that the enzyme may be responsible for the metabolism of materials that are incorporated from the environment, as well as for molecules that are excreted or secreted from the parasite to the environment. It also demonstrates the accessibility of the enzyme to an inhibitor or blocking antibody. In addition, the structure and sequence of the gene encoding AsGST1 have been determined. Southern-blot analyses of the AsGST1 gene suggests that it is a single-copy gene. The nucleotide sequence analysis revealed that the gene is composed of four exons and three introns, and potential regulatory elements were identified in the 5' flanking sequence.