Two enantiodivergent syntheses of balanol and the chemoenzymatic synthesis of oseltamivir

The present thesis outlines our latest findings on the reactivity of the Burgess reagent with oxiranes. Structural, mechanistic, and computational studies are presented. Included is the development of a (-)-menthyl version of the Burgess reagent and its application to the synthesis of enantiomerically pure ~-amino alcohols. This methodology has been exploited in the formal enantiodivergent synthesis of the (+)- and (-)-isomers of balanol. Also described is a second generation approach to both balanol enantiomers; each commencmg with the chemoenzymatic dihydroxylation of bromobenzene. This study also describes the steric and functional limitations of the toluene dioxygenase-mediated oxidation of benzoate esters. The metabolite derived from ethyl benzoate was employed in a formal synthesis of oseltamivir. Finally, several synthetic approaches to oseltamivir and its analogs are presented, each proceeding through a different vinyl aziridine derived from bromobenzene and ethyl benzoate.

Frecuencias alélicas y genotípicas de transportadores del fármaco oseltamivir, utilizado en el brote pandémico de influenza a H1n1, en una población del Noreste de México.

Tesis (Maestría en Ciencias con Acentuación en Inmunobiología) UANL, 2012.

ASAP ECMO : antibiotic, sedative and analgesic pharmacokinetics during extracorporeal membrane oxygenation : a multi-centre study to optimise drug therapy during ECMO

BACKGROUND: Given the expanding scope of extracorporeal membrane oxygenation (ECMO) and its variable impact on drug pharmacokinetics as observed in neonatal studies, it is imperative that the effects of the device on the drugs commonly prescribed in the intensive care unit (ICU) are further investigated. Currently, there are no data to confirm the appropriateness of standard drug dosing in adult patients on ECMO. Ineffective drug regimens in these critically ill patients can seriously worsen patient outcomes. This study was designed to describe the pharmacokinetics of the commonly used antibiotic, analgesic and sedative drugs in adult patients receiving ECMO. METHODS: This is a multi-centre, open-label, descriptive pharmacokinetic (PK) study. Eligible patients will be adults treated with ECMO for severe cardiac and/or respiratory failure at five Intensive Care Units in Australia and New Zealand. Patients will receive the study drugs as part of their routine management. Blood samples will be taken from indwelling catheters to investigate plasma concentrations of several antibiotics (ceftriaxone, meropenem, vancomycin, ciprofloxacin, gentamicin, piperacillin-tazobactum, ticarcillin-clavulunate, linezolid, fluconazole, voriconazole, caspofungin, oseltamivir), sedatives and analgesics (midazolam, morphine, fentanyl, propofol, dexmedetomidine, thiopentone). The PK of each drug will be characterised to determine the variability of PK in these patients and to develop dosing guidelines for prescription during ECMO. DISCUSSION: The evidence-based dosing algorithms generated from this analysis can be evaluated in later clinical studies. This knowledge is vitally important for optimising pharmacotherapy in these most severely ill patients to maximise the opportunity for therapeutic success and minimise the risk of therapeutic failure

Reactions of enantiopure cyclic diols with sulfuryl chloride

Monocyclic allylic cis-1,2-diols reacted with sulfuryl chloride at 0 °C in a regio- and stereo-selective manner to give 2-chloro-1-sulfochloridates, which were hydrolysed to yield the corresponding trans-1,2-chlorohydrins. At −78 °C, with very slow addition of sulfuryl chloride, cyclic sulfates were formed in good yields, proved to be very reactive with nucleophiles and rapidly decomposed on attempted storage. Reaction of a cyclic sulfate with sodium azide yielded a trans-azidohydrin without evidence of allylic rearrangement occurring. An enantiopure bicyclic cis-1,2-diol reacted with sulfuryl chloride to give, exclusively, a trans-1,2-dichloride enantiomer with retention of configuration at the benzylic centre and inversion at the non-benzylic centre; a mechanism is presented to rationalise the observation.

Cenários de impacto de uma eventual pandemia de gripe na população portuguesa : morbilidade, mortalidade e necessidade de cuidados de saúde

RESUMO - Introdução — O presente estudo descreve os cenários de impacto que uma eventual pandemia de gripe poderá ter na população portuguesa e nos serviços de saúde. Trata-se de uma versão actualizada dos cenários preliminares que têm vindo a ser elaborados e discutidos desde 2005. Material e métodos — Os cenários assumem que a pandemia ocorrerá em duas ondas das quais a primeira (taxa de ataque: 10%) será menos intensa do que a segunda (taxas de ataque: 20%, 25% ou 30%). Neste trabalho são descritos apenas os cenários respeitantes à situação mais grave (taxa de ataque global = 10% + 30%). A elaboração dos cenários utilizou o método proposto por Meltzer, M. I., Cox, N. J. e Fukuda, K. (1999) mas com quase todos os parâmetros adaptados à população portuguesa. Esta adaptação incidiu sobre: 1. duração da pandemia; 2. taxa de letalidade; 3. percentagem da população com risco elevado de complicações; 4. percentagem de doentes com suspeita de gripe que procurará consulta; 5. tempo entre o início dos sintomas e a procura de cuidados; 6. percentagem de doentes que terá acesso efectivo a antiviral; 7. taxa de hospitalização por gripe e tempo médio de hospitalização; 8. percentagem de doentes hospitalizados que necessitarão de cuidados intensivos (CI) e tempo de internamento em CI; 9. efectividade de oseltamivir para evitar complicações e morte. Resultados — Os cenários correspondentes à situação mais grave (taxa de ataque global: 10% + 30%) são apresentados sem qualquer intervenção e, também, com utilização de oseltamivir para fins terapêuticos. Os resultados sem intervenção para o cenário «provável» indicam: • número total de casos — 4 142 447; • número total de indivíduos a necessitar de consulta — 5 799 426; • número total de hospitalizações — 113 712; • número total de internamentos em cuidados intensivos — 17 057; • número total de óbitos — 32 051; • número total de óbitos, nas semanas com valor máximo — 1.a onda: 2551, 2.a onda: 7651. Quando os cenários foram simulados entrando em linha de conta com a utilização de oseltamivir (considerando uma efectividade de 10% e 30%), verificou-se uma redução dos valores dos óbitos e hospitalizações calculados. O presente artigo também apresenta a distribuição semanal, no período de desenvolvimento da pandemia, dos vários resultados obtidos. Discussão — Os resultados apresentados devem ser interpretados como «cenários» e não como «previsões». De facto, as incertezas existentes em relação à doença e ao seu agente não permitem prever com rigor suficiente os seus impactos sobre a população e sobre os serviços de saúde. Por isso, os cenários agora apresentados servem, sobretudo, para fins de planeamento. Assim, a preparação da resposta à eventual pandemia pode ser apoiada em valores cujas ordens de grandeza correspondem às situações de mais elevada gravidade. Desta forma, a sua utilização para outros fins é inadequada e é vivamente desencorajada pelos autores.

Characterization of recombinant influenza B viruses with key neuraminidase inhibitor resistance mutations

Objectives and methods: An influenza B virus plasmid-based rescue system was used to introduce site-specific mutations, previously observed in neuraminidase (NA) inhibitor-resistant viruses, into the NA protein of six recombinant viruses. Three mutations observed only among in vitro selected zanamivir-resistant influenza A mutants were introduced into the B/Beijing/1/87 virus NA protein, to change residue E116 to glycine, alanine or aspartic acid. Residue E116 was also mutated to valine, a mutation found in the clinic among oseltamivir-resistant viruses. An arginine to lysine change at position 291 (292 N2 numbering) mimicked that seen frequently in influenza A N2 clinical isolates resistant to oseltamivir. Similarly, an arginine to lysine change at position 149 (152 in N2 numbering) was made to reproduce the change found in the only reported zanamivir-resistant clinical isolate of influenza B virus. In vitro selection and prolonged treatment in the clinic leads to resistance pathways that require compensatory mutations in the haemagglutinin gene, but these appear not to be important for mutants isolated from immunocompetent patients. The reverse genetics system was therefore used to generate mutants containing only the NA mutation. Results and conclusions: With the exception of a virus containing the E116G mutation, mutant viruses were attenuated to different levels in comparison with wild-type virus. This attenuation was a result of altered NA activity or stability depending on the introduced mutation. Mutant viruses displayed increased resistance to zanamivir, oseltamivir and peramivir, with certain viruses displaying cross-resistance to all three drugs.

Design of multiligand inhibitors for the swine flu H1N1 neuraminidase binding site

Viral neuraminidase inhibitors such as oseltamivir and zanamivir prevent early virus multiplication by blocking sialic acid cleavage on host cells. These drugs are effective for the treatment of a variety of influenza subtypes, including swine flu (H1N1). The binding site for these drugs is well established and they were designed based on computational docking studies. We show here that some common natural products have moderate inhibitory activity for H1N1 neuraminidase under docking studies. Significantly, docking studies using AutoDock for biligand and triligand forms of these compounds (camphor, menthol, and methyl salicylate linked via methylene bridges) indicate that they may bind in combination with high affinity to the H1N1 neuraminidase active site. These results also indicate that chemically linked biligands and triligands of these natural products could provide a new class of drug leads for the prevention and treatment of influenza. This study also highlights the need for a multiligand docking algorithm to understand better the mode of action of natural products, wherein multiple active ingredients are present.

Recommendations for and compliance with social restrictions during implementation of school closures in the early phase of the influenza A (H1N1) 2009 outbreak in Melbourne, Australia

Background Localized reactive school and classroom closures were implemented as part of a suite of pandemic containment measures during the initial response to influenza A (H1N1) 2009 in Melbourne, Australia. Infected individuals, and those who had been in close contact with a case, were asked to stay in voluntary home quarantine and refrain from contact with visitors for seven days from the date of symptom onset or exposure to an infected person. Oseltamivir (Tamiflu®) was available for treatment or prophylaxis. Methods We surveyed affected families through schools involved in the closures. Analyses of responses were descriptive. We characterized recommendations made to case and contact households and quantified adherence to guidelines and antiviral therapy. Results Of the 314 respondent households, 51 contained a confirmed case. The prescribed quarantine period ranged from 1-14 days, reflecting logistic difficulties in reactive implementation relative to the stated guidelines. Household-level compliance with the requirement to stay at home was high (84.5%, 95% CI 79.3,88.5) and contact with children outside the immediate family infrequent. Conclusions Levels of compliance with recommendations in our sample were high compared with other studies, likely due to heightened public awareness of a newly introduced virus of uncertain severity. The variability of reported recommendations highlighted the difficulties inherent in implementing a targeted reactive strategy, such as that employed in Melbourne, on a large scale during a public health emergency. This study emphasizes the need to understand how public health measures are implemented when seeking to evaluate their effectiveness.

Characterization of H1N1 swine influenza viruses circulating in Canadian pigs in 2009

The 2009 pandemic H1N1 (pH1N1), of apparent swine origin, may have evolved in pigs unnoticed because of insufficient surveillance. Consequently, the need for surveillance of influenza viruses circulating in pigs has received added attention. In this study we characterized H1N1 viruses isolated from Canadian pigs in 2009. Isolates from May 2009 were comprised of hemagglutinin and neuraminidase (NA) genes of classical SIV origin in combination with the North American triple-reassortant internal gene (TRIG) cassette, here termed contemporary SIV (conSIV) H1N1. These conSIV H1N1 viruses were contiguous with the North American αH1 cluster, which was distinct from the pH1N1 isolates that were antigenically more related to the γH1 cluster. After the initial isolation of pH1N1 from an Alberta pig farm in early May 2009, pH1N1 was found several times in Canadian pigs. These pH1N1 isolates were genetically and antigenically homogeneous. In addition, H1N1 viruses bearing seasonal human H1 and N1 genes together with the TRIG cassette and an NA encoding an oseltamivir-resistance marker were isolated from pigs. The NS gene of one of these seasonal human-like SIV (shSIV) H1N1 isolates was homologous to pH1N1 NS, implicating reassortment between the two strains. Antigenic cross-reactivity was observed between pH1N1 and conSIV but not with shSIV H1N1. In summary, although there was cocirculation of pH1N1 with conSIV and shSIV H1N1 in Canadian pigs after May 2009, there was no evidence supporting the presence of pH1N1 in pigs prior to May 2009. The possibility for further reassortants being generated exists and should be closely monitored.

Perfil genotípico de resistência do vírus Influenza A (H1N1) pandêmico aos inibidores da neuraminidase em pacientes procedentes da mesorregião de Belém no período de maio de 2009 a maio de 2012

O vírus Influenza é o responsável pela gripe, uma doença que ocasiona milhões de mortes e hospitalizações todos os anos. Nas infecções severas, especialmente em pessoas com risco para complicações, os antivirais tornam-se os principais meios para o manejo clínico, merecendo especial destaque os inibidores da neuraminidase (INAs). De fato, na pandemia de 2009 a Organização Mundial da Saúde (OMS) recomendou o uso do oseltamivir para o tratamento dos doentes. Porém, devido à evolução genética viral, surgiram cepas com mutações no gene codificador da neuraminidase (NA) responsáveis por substituições aminoacídicas que levam à resistência aos fármacos INAs. Assim, a OMS passou a recomendar a vigilância de resistência genotípica para os vírus Influenza. Este trabalho teve como objetivos verificar a ocorrência de mutações no gene codificador da NA dos vírus Influenza A (H1N1) pandêmico que possam estar relacionadas à resistência aos INAs em cepas circulantes na mesorregião metropolitana de Belém no período de maio de 2009 a maio de 2012 e analisar, através da modelagem de proteínas, as substituições aminoacídicas da NA que possam estar influenciando na conformação protéica. Durante o período de estudo, foram recebidas no Laboratório de Vírus Respiratórios 2619 amostras clínicas de pacientes que apresentavam sinais e sintomas de infecção respiratória aguda com até cinco dias de evolução. Para a detecção do genoma viral foi feita a extração do RNA viral, seguida de RT-PCR em tempo real utilizando marcadores específicos para Influenza A H1N1pdm, resultando em 744 (28,4%) positivas. Parte das amostras positivas foram então inoculadas em células MDCK. Para as amostras isoladas em cultura de células, foi feita uma nova extração do RNA viral seguida de uma RT-PCR e semi-nested (PCR) utilizando iniciadores específicos para o gene NA, e posterior análise em sequenciador automático ABI Prism 3130xl (Applied Biosystems). A modelagem molecular da NA foi realizada através dos softwares SWISS-MODEL, MODELLER 9.10, PROCHECK, VERIFY3D e PYMOL. A análise parcial das sequências da neuraminidase nas amostras sequenciadas mostrou que não houve a circulação de cepas de vírus H1N1pdm com a mutação H275Y, a principal envolvida na resistência ao oseltamivir. Porém, em duas amostras foi identificada a substituição D199N que já foi relatada em vários estudos mostrando uma possível associação com o aumento da resistência ao oseltamivir. As amostras de 2012 apresentaram duas substituições (V241I e N369K) que estão relacionadas com um possível papel na compensação dos efeitos negativos causados pela mutação H275Y. A modelagem molecular mostrou que na mutação D199N houve uma alteração na estrutura da proteína NA próxima ao sítio de ligação ao antiviral. A análise filogenética revelou que as amostras de 2012 formaram um cluster isolado, demonstrando uma variação muito mais temporal do que geográfica. Este representa o primeiro estudo de resistência dos vírus Influenza H1N1pdm na mesorregião metropolitana de Belém, representando um importante instrumento para que os profissionais de saúde adotem estratégias mais eficazes no manejo da doença e no desenvolvimento de novos fármacos anti-influenza.

Eichhornia crassipes: an advantageous source of shikimic acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação de Eichhornia crassipes como fonte de ácido chiquímico

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Emerging contaminants in agricultural ecosystems: impact of selected pharmaceutical on water and soil ecology and pratical implications

Pharmaceuticals are useful tools to prevent and treat human and animal diseases. Following administration, a significant fraction of pharmaceuticals is excreted unaltered into faeces and urine and may enter the aquatic ecosystem and agricultural soil through irrigation with recycled water, constituting a significant source of emerging contaminants into the environment. Understanding major factors influencing their environmental fate is consequently needed to value the risk, reduce contamination, and set up bioremediation technologies. The antiviral drug Tamiflu (oseltamivir carboxylate, OC) has received recent attention due to the potential use as a first line defence against H5N1 and H1N1 influenza viruses. Research has shown that OC is not removed during conventional wastewater treatments, thus having the potential to enter surface water bodies. A series of laboratory experiments investigated the fate and the removal of OC in surface water systems in Italy and Japan and in a municipal wastewater treatment plant. A preliminary laboratory study investigated the persistence of the active antiviral drug in water samples from an irrigation canal in northern Italy (Canale Emiliano Romagnolo). After an initial rapid decrease, OC concentration slowly decreased during the remaining incubation period. Approximately 65% of the initial OC amount remained in water at the end of the 36-day incubation period. A negligible amount of OC was lost both from sterilized water and from sterilized water/sediment samples, suggesting a significant role of microbial degradation. Stimulating microbial processes by the addition of sediments resulted in reduced OC persistence. Presence of OC (1.5 μg mL-1) did not significantly affect the metabolic potential of the water microbial population, that was estimated by glyphosate and metolachlor mineralization. In contrast, OC caused an initial transient decrease in the size of the indigenous microbial population of water samples. A second laboratory study focused on basic processes governing the environmental fate of OC in surface water from two contrasting aquatic ecosystems of northern Italy, the River Po and the Venice Lagoon. Results of this study confirmed the potential of OC to persist in surface water. However, the addition of 5% of sediments resulted in rapid OC degradation. The estimated half-life of OC in water/sediment of the River Po was 15 days. After three weeks of incubation at 20 °C, more than 8% of 14C-OC evolved as 14CO2 from water/sediment samples of the River Po and Venice Lagoon. OC was moderately retained onto coarse sediments from the two sites. In water/sediment samples of the River Po and Venice Lagoon treated with 14C-OC, more than 30% of the 14C-residues remained water-extractable after three weeks of incubation. The low affinity of OC to sediments suggests that the presence of sediments would not reduce its bioavailability to microbial degradation. Another series of laboratory experiments investigated the fate and the removal of OC in two surface water ecosystems of Japan and in the municipal wastewater treatment plant of the city of Bologna, in Northern Italy. The persistence of OC in surface water ranged from non-detectable degradation to a half-life of 53 days. After 40 days, less than 3% of radiolabeled OC evolved as 14CO2. The presence of sediments (5%) led to a significant increase of OC degradation and of mineralization rates. A more intense mineralization was observed in samples of the wastewater treatment plant when applying a long incubation period (40 days). More precisely, 76% and 37% of the initial radioactivity applied as 14C-OC was recovered as 14CO2 from samples of the biological tank and effluent water, respectively. Two bacterial strains growing on OC as sole carbon source were isolated and used for its removal from synthetic medium and environmental samples, including surface water and wastewater. Inoculation of water and wastewater samples with the two OC-degrading strains showed that mineralization of OC was significantly higher in both inoculated water and wastewater, than in uninoculated controls. Denaturing gradient gel electrophoresis and quantitative PCR analysis showed that OC would not affect the microbial population of surface water and wastewater. The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in literature. In a series of laboratory experiments, the efficiency of a formulation using P. chrysosporium was evaluated for the removal of selected pharmaceuticals from wastewater samples. Addition of the fungus to samples of the wastewater treatment plant of Bologna significantly increased (P < 0.05) the removal of OC and three antibiotics, erythromycin, sulfamethoxazole, and ciprofloxacin. Similar effects were also observed in effluent water. OC was the most persistent of the four pharmaceuticals. After 30 days of incubation, approximately two times more OC was removed in bioremediated samples than in controls. The highest removal efficiency of the formulation was observed with the antibiotic ciprofloxacin. The studies included environmental aspects of soil contamination with two emerging veterinary contaminants, such as doramectin and oxibendazole, wich are common parasitic treatments in cattle farms.

Influenza A(H1N1) infection and severe cardiac dysfunction in adults: A case series

BACKGROUND: While viral myocarditis and heart failure are recognized and feared complications of seasonal influenza A infection, only limited information is available for 2009 influenza A(H1N1)-induced heart failure. METHODS AND MAIN FINDINGS: This case series summarizes the disease course of four patients with 2009 influenza A(H1N1) infection who were treated at our institution from November 2009 until September 2010. All patients presented with severe cardiac dysfunction (acute heart failure, cardiogenic shock or cardiac arrest due to ventricular fibrillation) as the leading symptom of influenza A(H1N1) infection. Two patients most likely had pre-existent cardiac pathologies, and three required catecholamine therapy to maintain hemodynamic function. Except for one patient who died before influenza A(H1N1) infection had been diagnosed, all patients received antiviral therapy with oseltamivir and supportive critical care. Acute respiratory distress syndrome due to influenza A(H1N1) infection developed in one patient. Heart function normalized in two of the three surviving patients but remained impaired in the other one at hospital discharge. CONCLUSIONS: Influenza A(H1N1) infection may be associated with severe cardiac dysfunction which can even be the leading clinical symptom at presentation. During an influenza pandemic, a thorough history may reveal flu-like symptoms and should indicate testing for H1N1 infection also in critically ill patients with acute heart failure.