Comparing effectiveness of top-down and bottom-up strategies in containing influenza

This research compares the performance of bottom-up, self-motivated behavioral interventions with top-down interventions targeted at controlling an "Influenza-like-illness". Both types of interventions use a variant of the ring strategy. In the first case, when the fraction of a person's direct contacts who are diagnosed exceeds a threshold, that person decides to seek prophylaxis, e.g. vaccine or antivirals; in the second case, we consider two intervention protocols, denoted Block and School: when a fraction of people who are diagnosed in a Census Block (resp., School) exceeds the threshold, prophylax the entire Block (resp., School). Results show that the bottom-up strategy outperforms the top-down strategies under our parameter settings. Even in situations where the Block strategy reduces the overall attack rate well, it incurs a much higher cost. These findings lend credence to the notion that if people used antivirals effectively, making them available quickly on demand to private citizens could be a very effective way to control an outbreak.     

Competitive Fitness of Oseltamivir-Sensitive and -Resistant Highly Pathogenic H5N1 Influenza Viruses in a Ferret Model

The fitness of oseltamivir-resistant highly pathogenic H5N1 influenza viruses has important clinical implications. We generated recombinant human A/Vietnam/1203/04 (VN; clade 1) and A/Turkey/15/06 (TK; clade 2.2) influenza viruses containing the H274Y neuraminidase (NA) mutation, which confers resistance to NA inhibitors, and compared the fitness levels of the wild-type (WT) and resistant virus pairs in ferrets. The VN-H274Y and VN-WT viruses replicated to similar titers in the upper respiratory tract (URT) and caused comparable disease signs, and none of the animals survived. On days 1 to 3 postinoculation, disease signs caused by oseltamivir-resistant TK-H274Y virus were milder than those caused by TK-WT virus, and all animals survived. We then studied fitness by using a novel approach. We coinoculated ferrets with different ratios of oseltamivir-resistant and -sensitive H5N1 viruses and measured the proportion of clones in day-6 nasal washes that contained the H274Y NA mutation. Although the proportion of VN-H274Y clones increased consistently, that of TK-H274Y virus decreased. Mutations within NA catalytic (R292K) and framework (E119A/K, I222L, H274L, and N294S) sites or near the NA enzyme active site (V116I, I117T/V, Q136H, K150N, and A250T) emerged spontaneously (without drug pressure) in both pairs of viruses. The NA substitutions I254V and E276A could exert a compensatory effect on the fitness of VN-H274Y and TK-H274Y viruses. NA enzymatic function was reduced in both drug-resistant H5N1 viruses. These results show that the H274Y NA mutation affects the fitness of two H5N1 influenza viruses differently. Our novel method of assessing viral fitness accounts for both virus-host interactions and virus-virus interactions within the host.The neuraminidase (NA) inhibitors (orally administered oseltamivir and inhaled zanamivir) are currently an important class of antiviral drugs available for the treatment of seasonal and pandemic influenza. Although administration of NA inhibitors may significantly reduce influenza virus transmission, it risks the emergence of drug-resistant variants (16, 32). The impact of drug resistance would depend on the fitness (i.e., infectivity in vitro and virulence and transmissibility in vivo) of the resistant virus. If the resistance mutation only modestly reduces the virus'' biological fitness and does not impair its replication efficiency and transmissibility, the effectiveness of antiviral treatment can be significantly impaired. The unexpected natural emergence and spread of oseltamivir-resistant variants (carrying the H274Y NA amino acid substitution) among seasonal H1N1 influenza viruses of the A/Brisbane/59/07 lineage demonstrated that drug-resistant viruses can be highly fit and transmissible in humans (11, 22, 29), although the fitness of these variants is not completely understood. They are hypothesized to have lower NA receptor affinity and more-optimal NA and hemagglutinin (HA) functional balance than do wild-type (WT) viruses (38). Fortunately, oseltamivir-resistant variants have rarely been reported to occur among the novel pandemic H1N1 influenza viruses that emerged in April 2009; therefore, initial data suggest that currently circulating wild-type viruses possibly possess greater fitness than drug-resistant viruses (45), although only retrospective epidemiological data can provide a conclusive answer. The key questions are whether the risk posed by NA inhibitor-resistant viruses can be assessed experimentally and what the most reliable approach may be.All NA inhibitor-resistant influenza viruses characterized to date have contained specific mutations in the NA molecule. Clinically derived drug-resistant viruses have carried mutations that are NA subtype specific and differ in accordance with the NA inhibitor used (12, 35). The most commonly observed mutations are H274Y and N294S in the influenza A N1 NA subtype, E119A/G/D/V and R292K in the N2 NA subtype, and R152K and D198N in influenza B viruses (35, 36). The fitness of NA inhibitor-resistant viruses has been studied in vitro and in vivo. Many groups have assessed their replicative capacity in MDCK cells, but this assay system can yield anomalous results (49), particularly in the case of low-passage clinical isolates. The mismatch between virus specificity and cellular receptors can be overcome by using cell lines engineered to express human-like α-2,6-linked sialyl cell surface receptors (MDCK-SIAT1) (15, 34) or a novel cell culture-based system that morphologically and functionally recapitulates differentiated normal human bronchial epithelial (NHBE) cells (24). Investigations in vivo typically compare replication efficiencies, clinical signs, and transmissibility levels between oseltamivir-resistant viruses and the corresponding wild-type virus. Initial studies found that NA inhibitor-resistant influenza viruses were severely compromised in vitro and in animal models (6, 17, 26) and thus led to the idea that resistant viruses will unlikely have an impact on epidemic and pandemic influenza. However, clinically derived H1N1 virus with the H274Y NA mutation (18) and reverse genetics-derived H3N2 virus with the E119V NA mutation (46) were subsequently found to possess biological fitness and transmissibility similar to those of drug-sensitive virus in direct-contact ferrets. Recent studies in a guinea pig model showed that recombinant human H3N2 influenza viruses carrying either a single E119V NA mutation or the double NA mutation E119V-I222V were transmitted efficiently by direct contact but not by aerosol (5).There is limited information about the fitness of NA inhibitor-resistant H5N1 influenza viruses. Although they are not efficiently transmitted from human to human, their pandemic potential remains a serious public health concern because of their virulence in humans (1, 4, 7). H5N1 viruses isolated from untreated patients are susceptible to the NA inhibitors oseltamivir and zanamivir (21), although oseltamivir-resistant variants with the H274Y NA mutation have been reported to occur in five patients after (9, 30) or before (41) treatment with oseltamivir. The World Health Organization reported the isolation of two oseltamivir-resistant H5N1 viruses from an Egyptian girl and her uncle (44) after oseltamivir treatment. The virus was moderately resistant and possessed an N294S NA mutation. Preliminary evidence suggests that the resistance mutation existed before transmission of the virus from birds to the patients and thus before initiation of treatment (41). We previously showed that wild-type A/Vietnam/1203/04 (H5N1) influenza virus and recombinants carrying either the H274Y or the N294S NA mutation reached comparable titers in MDCK and MDCK-SIAT1 cells and caused comparable mortality rates among BALB/c mice (48). In contrast, clinically derived A/Hanoi/30408/05 (H5N1) influenza virus with the H274Y NA mutation reproduced to lower titers than the oseltamivir-sensitive virus in the lungs of inoculated ferrets (30).In a ferret model, we compared the fitness levels of two pairs of H5N1 viruses in the absence of selective drug pressure. One virus of each pair was the wild type, while the other carried the H274Y NA mutation conferring oseltamivir resistance. The two viruses used, A/Vietnam/1203/04 (HA clade 1) and A/Turkey/15/06 (HA clade 2.2), differ in their pathogenicity to ferrets. Virus fitness was evaluated by two approaches. Using the traditional approach, we compared clinical disease signs, relative inactivity indexes, weight and temperature changes, and virus replication levels in the upper respiratory tract (URT). We then used a novel competitive fitness approach in which we genetically analyzed individual virus clones after coinfection of ferrets with mixtures of oseltamivir-sensitive and -resistant H5N1 viruses; thus, we determined virus-virus interactions within the host. We observed no difference between the resistant and sensitive virus of each pair in clinical signs or virus replication in the URT; however, analysis of virus-virus interactions within the host showed that the H274Y NA mutation affected the fitness of the two viruses differently. The oseltamivir-resistant A/Vietnam/1203/04-like virus outgrew its wild-type counterpart, while the oseltamivir-resistant A/Turkey/15/06-like virus showed less fitness than its wild-type counterpart.     

Strongyloides stercoralis hyperinfection in an immunocompetent patient with extreme eosinophilia

This report examines an unusual case of Srongyloides stercoralis hyperinfection in a 63-yr-old man. The patient had a history of vitamin B deficiency, on and off diarrhea, and clinical pellagra for a decade and a half. There was also evidence of extreme eosinophilia. The patient did not have any associated illness suggestive of immunosuppression. Treatment with ivermectin resulted in remarkable clinical improvement and reversion of eosinophil count to normal.     

Benzothiazole based inhibitors of p38alpha MAP kinase

Rational design, synthesis, and SAR studies of a novel class of benzothiazole based inhibitors of p38alpha MAP kinase are described. The issue of metabolic instability associated with vicinal phenyl, benzo[d]thiazol-6-yl oxazoles/imidazoles was addressed by the replacement of the central oxazole or imidazole ring with an aminopyrazole system. The proposed binding mode of this new class of p38alpha inhibitors was confirmed by X-ray crystallographic studies of a representative inhibitor (6a) bound to the p38alpha enzyme.     

Excipient Stability in Oral Solid Dosage Forms: A Review

The choice of excipients constitutes a major part of preformulation and formulation studies during the preparation of pharmaceutical dosage forms. The physical, mechanical, and chemical properties of excipients affect various formulation parameters, such as disintegration, dissolution, and shelf life, and significantly influence the final product. Therefore, several studies have been performed to evaluate the effect of drug-excipient interactions on the overall formulation. This article reviews the information available on the physical and chemical instabilities of excipients and their incompatibilities with the active pharmaceutical ingredient in solid oral dosage forms, during various drug-manufacturing processes. The impact of these interactions on the drug formulation process has been discussed in detail. Examples of various excipients used in solid oral dosage forms have been included to elaborate on different drug-excipient interactions.     

Inflammatory platelet-activating factor-like phospholipids in oxidized low density lipoproteins are fragmented alkyl phosphatidylcholines.

Oxidation of human low density lipoprotein (LDL) generates proinflammatory mediators and underlies early events in atherogenesis. We identified mediators in oxidized LDL that induced an inflammatory reaction in vivo, and activated polymorphonuclear leukocytes and cells ectopically expressing human platelet-activating factor (PAF) receptors. Oxidation of a synthetic phosphatidylcholine showed that an sn-1 ether bond confers an 800-fold increase in potency. This suggests that rare ether-linked phospholipids in LDL are the likely source of PAF-like activity in oxidized LDL. Accordingly, treatment of oxidized LDL with phospholipase A(1) greatly reduced phospholipid mass, but did not decrease its PAF-like activity. Tandem mass spectrometry identified traces of PAF, and more abundant levels of 1-O-hexadecyl-2-(butanoyl or butenoyl)-sn-glycero-3-phosphocholines (C(4)-PAF analogs) in oxidized LDL that comigrated with PAF-like activity. Synthesis showed that either C(4)-PAF was just 10-fold less potent than PAF as a PAF receptor ligand and agonist. Quantitation by gas chromatography-mass spectrometry of pentafluorobenzoyl derivatives shows the C(4)-PAF analogs were 100-fold more abundant in oxidized LDL than PAF. Oxidation of synthetic alkyl arachidonoyl phosphatidylcholine generated these C(4)-PAFs in abundance. These results show that quite minor constituents of the LDL phosphatidylcholine pool are the exclusive precursors for PAF-like bioactivity in oxidized LDL.