Wartime research on malaria chemotherapy

Malaria was a major problem for the opposing forces in World War II. During the first year of operations in the South West Pacific the casualties caused by this disease greatly exceeded the numbers of battle casualties. In response to this situation comprehensive research and development programs to discover new antimalarial drugs were undertaken in the United States and Britain. In both countries compounds synthesised by co-operating chemical laboratories were screened against bird malaria and those with high activity and low toxicity were tested in man. The wartime program in America was funded by the Office of Scientific Research and Development and co-ordinated through a specially designated body under the Committee on Medical Research of the National Research Council. It was an enormous undertaking involving a massive co-operative effort between pharmacologists, chemists, and clinical research scientists from American universities, the US Public Health Service, and the laboratories of commercial pharmaceutical companies. The British program, on a much smaller scale, was based on a co-operative arrangement between the research laboratories of Imperial Chemical Industries at Manchester, the Liverpool School of Tropical Medicine and the British Medical Research Council. The wartime programs in both countries identified a number of promising leads but lacked the resources to permit their rapid clinical evaluation against field strains of human malaria. This deficiency was overcome by experiments conducted by the Land Headquarters Medical Research Unit of the Australian Army in Cairns, Queensland with the use of army volunteers. Large scale clinical trials of the most promising compounds which emerged from the American and British programs were carried out in Australia. This co-operative endeavour among allied scientists resulted in a range of new drugs which have had an enduring influence on malaria chemotherapy.     

Two conserved lysines at the 50/20-kDa junction of myosin are necessary for triggering actin activation

Actin stimulates myosin's activity by inducing structural alterations that correlate with the transition from a weakly to a strongly bound state, during which time inorganic phosphate (P(i)) is released from myosin's active site. The surface loop at the 50/20-kDa junction of myosin (loop 2) is part of the actin interface. Here we demonstrate that elimination of two highly conserved lysines at the C-terminal end of loop 2 specifically blocks the ability of heavy meromyosin to undergo a weak to strong binding transition with actin in the presence of ATP. Removal of these lysines has no effect on strong binding in the absence of nucleotide, on the rate of ADP binding or release, or on the basal ATPase activity. We further show that the 16 amino acids of loop 2 preceding the lysine-rich region are not essential for actin activation, although they do modulate myosin's affinity for actin in the presence of ATP. We conclude that interaction of the conserved lysines with acidic residues in subdomain 1 of actin either triggers a structural change or stabilizes a conformation that is necessary for actin-activated release of P(i) and completion of the ATPase cycle.     

New Coleoptera records from New Brunswick, Canada: Eucnemidae

We report nine species of Eucnemidae new to the province and additional records for Onichodon canadensis (Brown) and Dromaeolus harringtoni Horn. Five species, Xylophilus cylindriformis (Horn), Entomophthalmus rufiolus (LeConte), Stethon pectorosus LeConte, Onichodon orchesides Newman, and Isarthrus rufipes (Melsheimer), are newly recorded for the Maritime provinces. This brings the total number of Eucnemidae recorded from New Brunswick to 15 species. Lindgren funnel traps are an effective tool for sampling the Eucnemidae.     

New Coleoptera records from New Brunswick, Canada: Mycetophagidae, Tetratomidae, and Melandryidae

We report 21 new species records for the Coleoptera fauna of New Brunswick, Canada, seven of which are new records for the Maritime provinces. Four species of Mycetophagidae (Litargus didesmus Say, Litargus tetrapilotus LeConte, Mycetophagus punctatus Say, and Mycetophagus quadriguttatus Müller) are newly reported for the province of New Brunswick. Litargus didesmus is newly recorded for the Maritime provinces. Seven species of Tetratomidae are added to the faunal list of New Brunswick: Eustrophus tomentosus Say, Penthe obliquata (Fabricius), and Tetratoma tessellata Melsheimer are new to New Brunswick: Hallomenus serricornis LeConte, Pisenus humeralis Kirby, Synstrophus repandus (Horn), and Tetratoma variegata Casey, which are newly recorded for New Brunswick and the Maritime provinces. Ten additional species of Melandryidae are reported from New Brunswick, of which Orchesia cultriformis Laliberté, Orchesia ovata Laliberté, Phloeotrya fusca (LeConte), Scotochroides antennatus Mank, Spilotus quadripustulatus (Melsheimer), Symphora flavicollis (Haldeman), Symphora rugosa (Haldeman), and Zilora hispida LeConte are new for the province, and Microscapha clavicornis LeConte and Zilora nuda Provancher are newly recorded for the Maritime provinces. In addition, we report numerous additional records for three species of Mycetophagidae and one species of Melandryidae previously recorded from New Brunswick that suggest these species are more widely distributed than previously known. Collection, habitat data, and distribution maps are presented for all these species.     

New Coleoptera records from New Brunswick, Canada: Tenebrionidae and Zopheridae

Thirteen species of Tenebrionidae are newly reported for New Brunswick, Canada. Paratenetus punctatus Spinola, Pseudocistela brevis (Say), Mycetochara foveata (LeConte), and Xylopinus aenescens LeConte are recorded for the first time from the Maritime provinces. Platydema excavatum (Say) is removed from the faunal list of New Brunswick, and the presence of Platydema americanum Laporte and Brullé for the province is confirmed. This brings the total number of species of Tenebrionidae known from New Brunswick to 42. Two species of Zopheridae, Bitoma crenata Fabricius and Synchita fuliginosa Melsheimer, are newly recorded for New Brunswick, bringing the number of species known from the province to four. Bitoma crenata is new to the Maritime provinces. Collection and habitat data are presented for these species.     

New Staphylinidae (Coleoptera) records with new collection data from New Brunswick and an addition to the fauna of Quebec: Staphylininae

Forty-four species of Staphylininae are newly reported from New Brunswick, bringing the total number of species known from the province to 126. Quedius criddlei (Casey) is reported for the first time from Quebec. Bisnius cephalotes (Gravenhorst) is removed from the faunal list of New Brunswick due to a lack of supporting voucher specimens. Additional locality data are presented for seven species either recently recorded from the province or with few previous records and little habitat data. We provide the first documented records of Atrecus americanus (Casey), Quedius erythrogaster Mannerheim, Quedius labradorensis labradorensis Smetana, Quedius plagiatus (Mannerheim), and Neobisnius terminalis (LeConte) from New Brunswick. Collection and habitat data are presented and discussed for all species.     

Identifying bottlenecks in transient and stable production of recombinant monoclonal-antibody sequence variants in chinese hamster ovary cells

The increasing demand for antibody-based therapeutics has emphasized the need for technologies to improve recombinant antibody titers from mammalian cell lines. Moreover, as antibody therapeutics address an increasing spectrum of indications, interest has increased in antibody engineering to improve affinity and biological activity. However, the cellular mechanisms that dictate expression and the relationships between antibody sequence and expression level remain poorly understood. Fundamental understanding of how mammalian cells handle high levels of transgene expression and of the relationship between sequence and expression are vital to the development of new antibodies and for increasing recombinant antibody titers. In this work, we analyzed a pair of mutants that vary by a single amino acid at Kabat position 49 (heavy-chain framework), resulting in differential transient and stable titers with no apparent loss of antigen affinity. Through analysis of mRNA, gene copy number, intracellular antibody content, and secreted antibody, we found that while translational/post-translational mechanisms are limiting in transient systems, it appears that the amount of available transgenic mRNA becomes the limiting event on stable integration of the recombinant genes. We also show that amino acid substitution at residue 49 results in production of a non-secreted HC variant and postulate that stable antibody expression is maintained at a level which prevents toxic accumulation of this HC-related protein. This study highlights the need for proper sequence engineering strategies when developing therapeutic antibodies and alludes to the early analysis of transient expression systems to identify the potential for aberrant stable expression behavior.     

Prevention of Vaginal SHIV Transmission in Macaques by a Coitally-Dependent Truvada Regimen

Background

Daily pre-exposure prophylaxis (PrEP) with Truvada (a combination of emtricitabine (FTC) and tenofovir (TFV) disoproxil fumarate (TDF)) is a novel HIV prevention strategy recently found to prevent HIV transmission in men who have sex with men and heterosexual couples. We previously showed that a coitally-dependent Truvada regimen protected macaques against rectal SHIV transmission. Here we examined FTC and tenofovir TFV exposure in vaginal tissues after oral dosing and assessed if peri-coital Truvada also protects macaques against vaginal SHIV infection.

Methods

The pharmacokinetic profile of emtricitabine (FTC) and tenofovir (TFV) was evaluated at first dose. FTC and TFV levels were measured in blood plasma, rectal, and vaginal secretions. Intracellular concentrations of FTC-triphosphate (FTC-TP) and TFV-diphosphate (TFV-DP) were measured in PBMCs, rectal tissues, and vaginal tissues. Efficacy of Truvada in preventing vaginal SHIV infection was assessed using a repeat-exposure vaginal SHIV transmission model consisting of weekly exposures to low doses of SHIV162p3. Six pigtail macaques with normal menstrual cycles received Truvada 24 h before and 2 h after each weekly virus exposure and six received placebo. Infection was monitored by serology and PCR amplification of SHIV RNA and DNA.

Results

As in humans, the concentration of FTC was higher than the concentration of TFV in vaginal secretions. Also as in humans, TFV levels in vaginal secretions were lower than in rectal secretions. Intracellular TFV-DP concentrations were also lower in vaginal tissues than in rectal tissues. Despite the low vaginal TFV exposure, all six treated macaques were protected from infection after 18 exposures or 4 full menstrual cycles. In contrast, all 6 control animals were infected.

Conclusions

We modeled a peri-coital regimen with two doses of Truvada and showed that it fully protected macaques from repeated SHIV exposures. Our results open the possibility for simplified PrEP regimens to prevent vaginal HIV transmission in women.