James W. Barlow

Microtubules as antiparasitic drug targets

Background: Parasitic diseases including malaria, leishmaniasis and schistosomiasis take a terrible toll of human life, health and productivity, especially in tropical and subtropical regions, and are also highly significant in animal health worldwide. Antiparasitic drugs are the mainstays of control of most of these diseases, but in many cases current therapies are inadequate and in some the situation is deteriorating because of drug resistance. Microtubules, as essential components of almost all eukaryotic cells, are proven drug targets in many helminth diseases and show promise as targets for the development of new antiprotozoal drugs. Objective: This article reviews the chemistry of the microtubule inhibitors in current use and under investigation as antiparasitic agents, their activities against the major parasites and their mechanisms of action. New directions in both inhibitor chemistry and biological evaluation are discussed. Conclusions: The most promising immediate avenues for discovery and design appear to lie in development of novel benzimidazoles for helminth parasites and compounds based on antimitotic herbicides for protozoal parasites. New understanding from functional genomics, structural biology and microtubular imaging will help accelerate the development of completely novel antiparasitic drugs targeting microtubules.

Medical Students' Knowledge, Perceptions, and Interest in Complementary and Alternative Medicine

BACKGROUND Complementary and alternative medicine (CAM) is a growing industry in the health care system. In Ireland, to date there has not been a study that evaluates the knowledge of, interest in, and attitude of Irish medical students toward CAM. OBJECTIVES This research can serve as a pilot study to inform Irish medical schools on the need to introduce CAM into the medical curriculum. MATERIALS AND METHODS The survey instrument was a modified design based on previously published studies carried out in other geographical areas. All medical students within the undergraduate and graduate entry programs (GEP) at the Royal College of Surgeons in Ireland were invited to participate in the study. SPSS software was used to analyze the results of the questionnaires. RESULTS The survey completion rate was 20.1%. A majority of students (78.4%) thought that CAM knowledge is important for their future career as physicians. Approximately 65% of students reported that they have not acquired sufficient knowledge about CAM from medical school, and 50.2% of students believe CAM should be incorporated into the medical curriculum. Preclinical years (49.4%) were suggested as the most appropriate time to learn about CAM. Knowledge of CAM modalities was generally rated as minimal or none by students. Among the 15 CAM modalities incorporated in the survey, massage, acupuncture, and meditation received the highest interest from students. Students who believe in a religion had a higher interest in CAM (p<0.05). In terms of their personal view, massage, spirituality, and acupuncture received the highest positive responses. Attitudes toward CAM were positive from students. Lower willingness to use CAM was seen in clinical students (p<0.05). CONCLUSIONS It is important for the faculty of Irish medical schools to consider the possibility of integrating CAM education into the conventional medical curriculum in a systematic manner to better prepare students in their future career.

Mast cell stabilisers.

Mast cells play a critical role in type 1 hypersensitivity reactions. Indeed, mast cell mediators are implicated in many different conditions including allergic rhinitis, conjunctivitis, asthma, psoriasis, mastocytosis and the progression of many different cancers. Thus, there is intense interest in the development of agents which prevent mast cell mediator release or which inhibit the actions of such mediators once released into the environment of the cell. Much progress into the design of new agents has been made since the initial discovery of the mast cell stabilising properties of khellin from Ammi visnaga and the clinical approval of cromolyn sodium. This review critically examines the progress that has been made in the intervening years from the design of new agents that target a specific signalling event in the mast cell degranulation pathway to those agents which have been developed where the precise mechanism of action remains elusive. Particular emphasis is also placed on clinically used drugs for other indications that stabilise mast cells and how this additional action may be harnessed for their clinical use in disease processes where mast cells are implicated.

Synthesis and evaluation of phosphoramidate and phosphorothioamidate analogues of amiprophos methyl as potential antimalarial agents.

A series of phosphoramidate and phosphorothioamidate compounds based on the lead antitubulin herbicidal agents amiprophos methyl (APM) and butamifos were synthesised and evaluated for antimalarial activity. Of these compounds, phosphorothioamidates were more active than their oxo congeners and the nature of both aryl and amido substituents influenced the desired activity. The most active compound was 46, O-ethyl-O-(2-methyl-4-nitrophenyl)-N-cyclopentyl phosphorothioamidate, which was more effective than the lead compound.

Synthesis and evaluation of dimeric 1,2,3,4-tetrahydro-naphthalenylamine and indan-1-ylamine derivatives with mast cell-stabilising and anti-allergic activity.

In a continuation of our studies into 4-Amino-3,4-dihydro-2H-naphthalen-1-ones as novel modulators of allergic and inflammatory phenomena, we have extended our work to include dimeric analogues. Of these derivatives, the most promising activity was seen with tertiary amine 58a, which exhibited potent mast cell-stabilising activity in vitro against a variety of stimuli and also in vivo against passive cutaneous anaphylaxis.

Antimitotic herbicides bind to an unidentified site on malarial parasite tubulin and block development of liver-stage Plasmodium parasites.

Malarial parasites are exquisitely susceptible to a number of microtubule inhibitors but most of these compounds also affect human microtubules. Herbicides of the dinitroaniline and phosphorothioamidate classes however affect some plant and protozoal cells but not mammalian ones. We have previously shown that these herbicides block schizogony in erythrocytic parasites of the most lethal human malaria, Plasmodium falciparum, disrupt their mitotic spindles, and bind selectively to parasite tubulin. Here we show for the first time that the antimitotic herbicides also block the development of malarial parasites in the liver stage. Structure-based design of novel antimalarial agents binding to tubulin at the herbicide site, which presumably exists on (some) parasite and plant tubulins but not mammalian ones, can therefore constitute an important transmission blocking approach. The nature of this binding site is controversial, with three overlapping but non-identical locations on α-tubulin proposed in the literature. We tested the validity of the three sites by (i) using site-directed mutagenesis to introduce six amino acid changes designed to occlude them, (ii) producing the resulting tubulins recombinantly in Escherichia coli and (iii) measuring the affinity of the herbicides amiprophosmethyl and oryzalin for these proteins in comparison with wild-type tubulins by fluorescence quenching. The changes had little or no effect, with dissociation constants (Kd) no more than 1.3-fold (amiprophosmethyl) or 1.6-fold (oryzalin) higher than wild-type. We conclude that the herbicides impair Plasmodium liver stage as well as blood stage development but that the location of their binding site on malarial parasite tubulin remains to be proven.

Interprofessional ethics and professionalism debates: findings from a study involving physiotherapy and pharmacy students.

Abstract Ethics is a core component of healthcare curricula and may provide ideal content for interprofessional education (IPE). An IPE debate in ethics and professionalism was developed for first year undergraduate pharmacy and physiotherapy students. A controlled “before-and-after” study was conducted. The opinion of students on IPE, the debate topics and debating was determined before and after the debate. While there was no impact on attitudes to IPE or healthcare professionals, students agreed that debating ethics through IPE was a valid teaching modality. Students found the debates challenging. They stimulated critical thinking and interest in complex and controversial issues. Students also found it of benefit to work as a team. We conclude that in-class debate is a useful way of learning together.

Synthesis and evaluation of 4-amino-3,4-dihydro-2H-naphthalen-1-one derivatives as mast cell stabilising and anti-inflammatory compounds

A novel series of amine and amide derivatives of 4-amino-3,4-dihydro-2H-naphthalen-1-one were synthesised. The amine derivatives were evaluated for mast cell stabilising activity in rodent mast cell preparations against the reference compound disodium cromoglycate and found to possess significant activity in vitro. The amide compounds were evaluated in an in vivo murine model for anti-inflammatory activity.

Synthesis of novel mast cell-stabilising and anti-allergic 1,2,3,4-tetrahydro-1-naphthalenols and related compounds

In a continuation of our studies into indan and tetralin systems as novel modulators of allergic and inflammatory phenomena, we have extended our work to include dimers linked via C-C bonds. Of these compounds, 2-Benzyl-2-[2-phenyl-1-ethenyl]-1,2,3,4-tetrahydro-1-naphthalenol 12 exhibited most promising activity both in vitro and in vivo.

Synthesis and pharmacological evaluation of the individual stereoisomers of 3-[methyl(1,2,3,4-tetrahydro-2-naphthalenyl)amino]-1-indanone, a potent mast cell stabilising agent

Each stereoisomer of 3-[methyl(1,2,3,4-tetrahydro-2-naphthalenyl)amino]-1-indanone, 1a-d, was prepared and evaluated in vitro for its ability to prevent mediator release induced by different degranulating agents from rodent mast cells and also in vivo against passive cutaneous anaphylaxis. The manner in which the stereoisomers prevented direct membrane activation was found to be highly dependent on the stereochemistry of the individual isomers. Stereoisomer 1b was the most active isomer in vivo, exhibiting superior activity to disodium cromoglycate.