Richard J. Wall

The PAIN Study: Paracetamol, Aspirin and Ibuprofen New Tolerability Study

AbstractObjective: This study aimed to compare directly aspirin (acetylsalicylic acid), ibuprofen and paracetamol (acetaminophen), first-line analgesics which are generally well tolerated, from a safety perspective in general practice. Methods: This was a blinded, multicentre study in general practice of up to 7 days of aspirin, paracetamol (both up to 3g daily) or ibuprofen (up to 1.2g daily), administered for common painful conditions, using patient-generated data with physician assistance. The main outcome was the rate of significant adverse events (serious, severe or moderate events, events resulting in treatment discontinuation or a physician visit). Statistical analysis tested for equivalence between ibuprofen and paracetamol, and for difference with aspirin. Results: 1108 general practitioners included 8677 adults (2900 aspirin, 2886 ibuprofen, 2888 paracetamol; three patients had no code label number). 8633 (99.5%) were evaluable, of whom 8233 (95%) adhered to the study protocol. The main indications were musculoskeletal or back pain (48%), sore throat, the common cold and flu (31%). Rates of significant adverse events were: aspirin 18.7%, ibuprofen 13.7%, and paracetamol 14.5%. Ibuprofen was statistically equivalent to paracetamol. Both were significantly better tolerated than aspirin (p < 0.001). Total gastrointestinal events (including dyspepsia) and abdominal pain were less frequent with ibuprofen (4 and 2.8%, respectively) than with paracetamol (5.3 and 3.9%) or aspirin (7.1 and 6.8%) [all p < 0.035]. There were six cases of non-serious gastrointestinal bleeding, four with paracetamol and two with aspirin, and one case of peptic ulcer with aspirin. Conclusion: The overall tolerability of ibuprofen in this large-scale study was equivalent to that of paracetamol and better than that of aspirin. These findings could lead to a reassessment of the use of first-line analgesics for the short-term management of painful conditions in general practice, recommending ibuprofen first, because of the poor tolerability of aspirin and the potential risks of paracetamol overdose.

Genome-wide functional analysis of Plasmodium protein phosphatases reveals key regulators of parasite development and differentiation.

Summary Reversible protein phosphorylation regulated by kinases and phosphatases controls many cellular processes. Although essential functions for the malaria parasite kinome have been reported, the roles of most protein phosphatases (PPs) during Plasmodium development are unknown. We report a functional analysis of the Plasmodium berghei protein phosphatome, which exhibits high conservation with the P. falciparum phosphatome and comprises 30 predicted PPs with differential and distinct expression patterns during various stages of the life cycle. Gene disruption analysis of P. berghei PPs reveals that half of the genes are likely essential for asexual blood stage development, whereas six are required for sexual development/sporogony in mosquitoes. Phenotypic screening coupled with transcriptome sequencing unveiled morphological changes and altered gene expression in deletion mutants of two N-myristoylated PPs. These findings provide systematic functional analyses of PPs in Plasmodium, identify how phosphatases regulate parasite development and differentiation, and can inform the identification of drug targets for malaria.

Comparative Tolerability of Paracetamol, Aspirin and Ibuprofen for Short-Term Analgesia in Patients with Musculoskeletal Conditions: Results in 4291 Patients

Abstract The aim of this blinded, randomised, multicentre study was to compare the tolerability of aspirin, paracetamol and ibuprofen in common pain resulting from musculoskeletal conditions (MSC) in general practice with patients with other non-MSC pain conditions. Patients took aspirin, paracetamol (both up to 3g daily) or ibuprofen (up to 1.2g daily) for up to 7 days. The main outcome was the rate of significant adverse events (SGAE). Four thousand two hundred and ninety one patients with MSC were evaluable (1436 aspirin, 1423 paracetamol, 1432 ibuprofen) and 4101 (95.5%) were per-protocol. A group of 4342 patients included for other (non-MSC) mild to moderate pain conditions was used for comparison. In the MSC group, SGAE were reported by 20.5% of patients with aspirin, 17.0% with paracetamol and 15.0% with ibuprofen. Ibuprofen was statistically equivalent to paracetamol and better tolerated than aspirin (p<0.000l). Ibuprofen was associated with fewer digestive system AE (4.4%) than aspirin (8.6%, p<0.000l) and paracetamol (6.5%, p<0.02). The non-MSC group showed similar inter-treatment differences, but experienced fewer SGAE. No serious digestive events were observed with any of the three treatments in either group. These results show that in patients with mild to moderate pain resulting from MSC, ibuprofen given in OTC doses for 6 days is as well tolerated as paracetamol and better tolerated than aspirin.

Gastrointestinal Tolerability of Ibuprofen Compared with Paracetamol and Aspirin at Over-the-Counter Doses

This multicentre, randomized, investigator-blinded, parallel-group study compared the gastrointestinal (GI) tolerability of ibuprofen, paracetamol and aspirin at over-the-counter doses for common pain indications. Patients (of whom 8633 were evaluable) took either ibuprofen up to 1200 mg daily, or paracetamol or aspirin, each up to 3000 mg daily, for 1–7 days. The main outcome was the proportion of patients with GI adverse events. There were significantly more patients who suffered GI adverse events, principally abdominal pain, dyspepsia, nausea and diarrhoea, with aspirin (18.5%) than with ibuprofen (11.5%), but the difference between ibuprofen and paracetamol (13.1%) was not significant. Significantly more of those patients with a history of non-ulcer GI disease (n = 371) developed GI adverse events than did those with no such history; the incidence of GI adverse events in both groups was lowest with ibuprofen. More women than men experienced GI adverse events (15.5% versus 12.8%). The higher incidence of GI adverse events with aspirin was evident from the first day of treatment. In conclusion, the GI tolerability of ibuprofen, at over-the-counter doses of up to 1200 mg daily for up to 7 days, was at least as good as that of paracetamol and significantly better than that of aspirin.

An Ancient Protein Phosphatase, SHLP1, Is Critical to Microneme Development in Plasmodium Ookinetes and Parasite Transmission

Summary Signaling pathways controlled by reversible protein phosphorylation (catalyzed by kinases and phosphatases) in the malaria parasite Plasmodium are of great interest, for both increased understanding of parasite biology and identification of novel drug targets. Here, we report a functional analysis in Plasmodium of an ancient bacterial Shewanella-like protein phosphatase (SHLP1) found only in bacteria, fungi, protists, and plants. SHLP1 is abundant in asexual blood stages and expressed at all stages of the parasite life cycle. shlp1 deletion results in a reduction in ookinete (zygote) development, microneme formation, and complete ablation of oocyst formation, thereby blocking parasite transmission. This defect is carried by the female gamete and can be rescued by direct injection of mutant ookinetes into the mosquito hemocoel, where oocysts develop. This study emphasizes the varied functions of SHLP1 in Plasmodium ookinete biology and suggests that it could be a novel drug target for blocking parasite transmission.

Unique apicomplexan IMC sub-compartment proteins are early markers for apical polarity in the malaria parasite

Summary The phylum Apicomplexa comprises over 5000 intracellular protozoan parasites, including Plasmodium and Toxoplasma, that are clinically important pathogens affecting humans and livestock. Malaria parasites belonging to the genus Plasmodium possess a pellicle comprised of a plasmalemma and inner membrane complex (IMC), which is implicated in parasite motility and invasion. Using live cell imaging and reverse genetics in the rodent malaria model P. berghei, we localise two unique IMC sub-compartment proteins (ISPs) and examine their role in defining apical polarity during zygote (ookinete) development. We show that these proteins localise to the anterior apical end of the parasite where IMC organisation is initiated, and are expressed at all developmental stages, especially those that are invasive. Both ISP proteins are N-myristoylated, phosphorylated and membrane-bound. Gene disruption studies suggest that ISP1 is likely essential for parasite development, whereas ISP3 is not. However, an absence of ISP3 alters the apical localisation of ISP1 in all invasive stages including ookinetes and sporozoites, suggesting a coordinated function for these proteins in the organisation of apical polarity in the parasite.

The Repeat Region of the Circumsporozoite Protein is Critical for Sporozoite Formation and Maturation in Plasmodium

The circumsporozoite protein (CSP) is the major surface protein of the sporozoite stage of malaria parasites and has multiple functions as the parasite develops and then migrates from the mosquito midgut to the mammalian liver. The overall structure of CSP is conserved among Plasmodium species, consisting of a species-specific central tandem repeat region flanked by two conserved domains: the NH2-terminus and the thrombospondin repeat (TSR) at the COOH-terminus. Although the central repeat region is an immunodominant B-cell epitope and the basis of the only candidate malaria vaccine in Phase III clinical trials, little is known about its functional role(s). We used the rodent malaria model Plasmodium berghei to investigate the role of the CSP tandem repeat region during sporozoite development. Here we describe two mutant parasite lines, one lacking the tandem repeat region (ΔRep) and the other lacking the NH2-terminus as well as the repeat region (ΔNΔRep). We show that in both mutant lines oocyst formation is unaffected but sporozoite development is defective.

Evaluation of Ibuprofen vs Paracetamol Analgesic Activity Using a Sore Throat Pain Model

AbstractObjective: To validate a slightly modified sore throat pain model by comparing the analgesic efficacy of ibuprofen with that of paracetamol. Design: A double-blind, double-dummy study was conducted. Setting: Nineteen primary care centres in France. Patients: Adults consulting their general practitioner with acute sore throat of a maximum of two days’ duration. Interventions: Patients (n = 113) with acute pain associated with tonsillo-pharyngitis randomly received either 400mg ibuprofen or 1000mg paracetamol. The study design included repeated administration up to 48 hours to assess tolerability. Main Outcome Measures: At hourly intervals for 6 hours after the first dose of treatment, the patients evaluated pain intensity on swallowing, difficulty in swallowing and global pain relief according to visual analogue scales. Results: Ibuprofen 400mg was significantly more effective than paracetamol 1000mg in all three ratings, at all time-points for pain intensity and difficulty in swallowing, and from two hours onwards for pain relief. There were no serious adverse effects and no statistically significant difference in the incidence of adverse events in the two treatment groups. Conclusions: Sore throat pain provided a sensitive model to assess the analgesic efficacy of class I analgesics and discriminated between the analgesic efficacy of ibuprofen and paracetamol. Sore throat is a very common complaint and practising physicians should consider ibuprofen as an effective alternative to paracetamol in the treatment of sore throat pain. The sore throat model should be considered by researchers as a sensitive assay of analgesic activity.

Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes.

Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

The Plasmodium Class XIV Myosin, MyoB, Has a Distinct Subcellular Location in Invasive and Motile Stages of the Malaria Parasite and an Unusual Light Chain.

Background: Malaria parasites possess two unusual class XIV myosins, myosin A that drives gliding motility and myosin B that is uncharacterized. Results: Myosin B is located at the extreme apical end of motile and invasive parasites, binding a very large and unusual light chain. Conclusion: Myosin B differs substantially from myosin A in location and function. Significance: An unusual myosin and its light chain extend the known diversity of these families. Myosin B (MyoB) is one of the two short class XIV myosins encoded in the Plasmodium genome. Class XIV myosins are characterized by a catalytic “head,” a modified “neck,” and the absence of a “tail” region. Myosin A (MyoA), the other class XIV myosin in Plasmodium, has been established as a component of the glideosome complex important in motility and cell invasion, but MyoB is not well characterized. We analyzed the properties of MyoB using three parasite species as follows: Plasmodium falciparum, Plasmodium berghei, and Plasmodium knowlesi. MyoB is expressed in all invasive stages (merozoites, ookinetes, and sporozoites) of the life cycle, and the protein is found in a discrete apical location in these polarized cells. In P. falciparum, MyoB is synthesized very late in schizogony/merogony, and its location in merozoites is distinct from, and anterior to, that of a range of known proteins present in the rhoptries, rhoptry neck or micronemes. Unlike MyoA, MyoB is not associated with glideosome complex proteins, including the MyoA light chain, myosin A tail domain-interacting protein (MTIP). A unique MyoB light chain (MLC-B) was identified that contains a calmodulin-like domain at the C terminus and an extended N-terminal region. MLC-B localizes to the same extreme apical pole in the cell as MyoB, and the two proteins form a complex. We propose that MLC-B is a MyoB-specific light chain, and for the short class XIV myosins that lack a tail region, the atypical myosin light chains may fulfill that role.