Oseltamivir in seasonal, avian H5N1 and pandemic 2009 A/H1N1 influenza: pharmacokinetic and pharmacodynamic characteristics.

Oseltamivir is the ester-type prodrug of the neuraminidase inhibitor oseltamivir carboxylate. It has been shown to be an effective treatment for both seasonal influenza and the recent pandemic 2009 A/H1N1 influenza, reducing both the duration and severity of the illness. It is also effective when used preventively. This review aims to describe the current knowledge of the pharmacokinetic and pharmacodynamic characteristics of this agent, and to address the issue of possible therapeutic drug monitoring. According to the currently available literature, the pharmacokinetics of oseltamivir carboxylate after oral administration of oseltamivir are characterized by mean ± SD bioavailability of 79 ± 12%, apparent clearance of 25.3 ± 7.0 L/h, an elimination half-life of 7.4 ± 2.5 hours and an apparent terminal volume of distribution of 267 ± 122 L. A maximum plasma concentration of 342 ± 83 μg/L, a time to reach the maximum plasma concentration of 4.2 ± 1.1 hours, a trough plasma concentration of 168 ± 32 μg/L and an area under the plasma concentration-time curve from 0 to 24 hours of 6110 ± 1330 μg · h/L for a 75 mg twice-daily regimen were derived from literature data. The apparent clearance is highly correlated with renal function, hence the dosage needs to be adjusted in proportion to the glomerular filtration rate. Interpatient variability is moderate (28% in apparent clearance and 46% in the apparent central volume of distribution); there is no indication of significant erratic or limited absorption in given patient subgroups. The in vitro pharmacodynamics of oseltamivir carboxylate reveal wide variation in the concentration producing 50% inhibition of influenza A and B strains (range 0.17-44 μg/L). A formal correlation between systemic exposure to oseltamivir carboxylate and clinical antiviral activity or tolerance in influenza patients has not yet been demonstrated; thus no formal therapeutic or toxic range can be proposed. The pharmacokinetic parameters of oseltamivir carboxylate after oseltamivir administration (bioavailability, apparent clearance and the volume of distribution) are fairly predictable in healthy subjects, with little interpatient variability outside the effect of renal function in all patients and bodyweight in children. Thus oseltamivir carboxylate exposure can probably be controlled with sufficient accuracy by thorough dosage adjustment according to patient characteristics. However, there is a lack of clinical study data on naturally infected patients. In addition, the therapeutic margin of oseltamivir carboxylate is poorly defined. The usefulness of systematic therapeutic drug monitoring in patients therefore appears to be questionable; however, studies are still needed to extend the knowledge to particular subgroups of patients or dosage regimens.

Modelling scenarios of diffusion and control of pandemic influenza, italy

En aquest article es resumeixen els resultats publicats en un informe de l' ISS (Istituto Superiore di Sanità) del desembre de 2006, sobre un model matemàtic desenvolupat per un grup de treball que inclou a investigadors de les Universitats de Trento, Pisa i Roma, i els Instituts Nacionals de Salut (Istituto Superiore di Sanità, ISS), per avaluar i mesurar l'impacte de la transmissió i el control de la pandèmia de grip

Pandemic 2009 A(H1N1) infection requiring hospitalization of elderly Spanish adults.

To describe the clinical presentation and prognosis of elderly adults hospitalized with pandemic 2009 A(H1N1) influenza infection and to compare these data with those of younger patients. DESIGN: Prospective, observational, multicenter study. SETTING: Thirteen hospitals in Spain. PARTICIPANTS: Adults admitted to the hospital with confirmed pandemic 2009 A(H1N1) influenza infection. MEASUREMENTS: Demographic, clinical, laboratory, radiological, and outcome variables. RESULTS: Between June 12 and November 10, 2009, 585 adults with confirmed 2009 A(H1N1) influenza were hospitalized, of whom 50 (8.5%) were aged 65 and older (median age 72, range 65-87). Older adults (≥ 65) were more likely to have associated comorbidities (88.0% vs 51.2%; P < .001), primarily chronic pulmonary diseases (46.0% vs 27.3%; P < .001). Lower respiratory tract symptoms and signs such as dyspnea (60.0% vs 45.6%) and wheezing (46.0% vs 27.8%; P = .007) were also more common in these elderly adults, although pulmonary infiltrates were present in just 14 (28.0%) of the older adults, compared with 221 (41.3%) of the younger adults (P = .06). Multilobar involvement was less frequent in elderly adults with pulmonary infiltrates than younger adults with pulmonary infiltrates (21.4% vs 60.0%; P = .05). Rhinorrhea (4.0% vs 21.9%; P = .003), myalgias (42.0% vs 59.1%; P = .01), and sore throat (14.0% vs 29.2%; P = .02) were more frequent in younger adults. Early antiviral therapy (<48 hours) was similar in the two groups (34.0% vs 37.9%; P = .58). Two older adults (4.0%) died during hospitalization, compared with 11 (2.1%) younger adults (P = .30). CONCLUSION: Elderly adults with 2009 A(H1N1) influenza had fewer viral-like upper respiratory symptoms than did younger adults. Pneumonia was more frequent in younger adults. No significant differences were observed in hospital mortality.

Mouse CD11c(+) B220(+) Gr1(+) plasmacytoid dendritic cells develop independently of the T-cell lineage.

The developmental origin of dendritic cells (DCs) is controversial. In the mouse CD8alpha(+) and CD8alpha(-) DC subsets are often considered to be of lymphoid and myeloid origin respectively, although evidence on this point is conflicting. Very recently a novel CD11c(+) B220(+) DC subset has been identified that appears to be the murine counterpart to interferon alpha (IFNalpha)-producing human plasmacytoid DCs (PDCs). We show here that CD11c(+) B220(+) mouse PDCs, like human PDCs, are present in the thymus and express T lineage markers such as CD8alpha and CD4. However, the intrathymic development of PDCs can be completely dissociated from immature T lineage cells in mixed chimeras established with bone marrow cells from mice deficient for either Notch-1 or T-cell factor 1, two independent mutations that severely block early T-cell development. Our data indicate that thymic PDCs do not arise from a bipotential T/DC precursor.

Delta-like 4 is the essential, nonredundant ligand for Notch1 during thymic T cell lineage commitment.

Thymic T cell lineage commitment is dependent on Notch1 (N1) receptor-mediated signaling. Although the physiological ligands that interact with N1 expressed on thymic precursors are currently unknown, in vitro culture systems point to Delta-like 1 (DL1) and DL4 as prime candidates. Using DL1- and DL4-lacZ reporter knock-in mice and novel monoclonal antibodies to DL1 and DL4, we show that DL4 is expressed on thymic epithelial cells (TECs), whereas DL1 is not detected. The function of DL4 was further explored in vivo by generating mice in which DL4 could be specifically inactivated in TECs or in hematopoietic progenitors. Although loss of DL4 in hematopoietic progenitors did not perturb thymus development, inactivation of DL4 in TECs led to a complete block in T cell development coupled with the ectopic appearance of immature B cells in the thymus. These immature B cells were phenotypically indistinguishable from those developing in the thymus of conditional N1 mutant mice. Collectively, our results demonstrate that DL4 is the essential and nonredundant N1 ligand responsible for T cell lineage commitment. Moreover, they strongly suggest that N1-expressing thymic progenitors interact with DL4-expressing TECs to suppress B lineage potential and to induce the first steps of intrathymic T cell development.

T cell fate specification and alphabeta/gammadelta lineage commitment.

The development of T cells from pluripotent stem cells involves a coordinated series of lineage-commitment steps. Common lymphoid precursors in the fetal liver or adult bone marrow must first choose between a T, B or NK cell fate. Committed T cell precursors in the thymus then differentiate into cells committed to the alphabeta or gammadelta lineages. Recent advances have been made in our understanding of the mechanisms underlying T cell fate specification and alphabeta/gammadelta lineage divergence.

A critical lineage-nonspecific role for pTalpha in mediating allelic and isotypic exclusion in TCRbeta-transgenic mice.

Although it is well established that early expression of TCRbeta transgenes in the thymus leads to efficient inhibition of both endogenous TCRbeta and TCRgamma rearrangement (also known as allelic and "isotypic" exclusion, respectively) the role of pTalpha in these processes remains controversial. Here, we have systematically re-evaluated this issue using three independent strains of TCRbeta-transgenic mice that differ widely in transgene expression levels, and a sensitive intracellular staining assay that detects endogenous TCRVbeta expression in individual immature thymocytes. In the absence of pTalpha, both allelic and isotypic exclusion were reversed in all three TCRbeta-transgenic strains, clearly demonstrating a general requirement for pre-TCR signaling in the inhibition of endogenous TCRbeta and TCRgamma rearrangement. Both allelic and isotypic exclusion were pTalpha dose dependent when transgenic TCRbeta levels were subphysiological. Moreover, pTalpha-dependent allelic and isotypic exclusion occurred in both alphabeta and gammadelta T cell lineages, indicating that pre-TCR signaling can potentially be functional in gammadelta precursors. Finally, levels of endogenous RAG1 and RAG2 were not down-regulated in TCRbeta-transgenic immature thymocytes undergoing allelic or isotypic exclusion. Collectively, our data reveal a critical but lineage-nonspecific role for pTalpha in mediating both allelic and isotypic exclusion in TCRbeta-transgenic mice.

Identification by a monoclonal antibody of a glycolipid highly expressed by cells from the human myeloid lineage.

A monoclonal antibody (MAb) HL-C5, which bound selectively to cells of the myeloid lineage tested, was derived from a fusion between P3/NS2/1-AG8 myeloma cells and splenocytes from a mouse immunized with cells of the promyelocytic leukemia line HL-60. Among a panel of 29 human cell lines derived from either hematopoietic or solid tumors, MAb HL-C5 was found to react exclusively with cells from the five differentiated acute myeloid leukemia lines, HL-60, ML1, ML2, ML3, KG-1B and not with the less differentiated myeloid lines. Fluorescence-activated cell sorter analysis of normal bone marrow samples confirmed that the reactivity of MAb HL-C5 was limited to myeloid cells, from the promyelocytic stage of differentiation to the mature granulocytes. Indirect immunoperoxidase staining of cytocentrifuge preparations of normal bone marrow and peripheral blood leukocytes confirmed these results and showed that MAb HL-C5 stained neutrophils but not eosinophils or basophils. The antigen recognized by HL-C5 was recovered in the upper phase of chloroform-methanol-water lipid extracts prepared from HL-60 cells. By competitive binding experiments, it was found that MAb HL-C5 recognizes the same antigenic determinant as MAb WGHS 29-1, which has been reported to react with glycolipids containing the sugar sequence lacto-N-fucopentaose 111. Autoradiographs of thin layer chromatograms of HL-60 glycolipid extracts which were revealed by incubation with MAb HL-C5 or WGHS 29-1 followed by the addition of 125I-labelled rabbit anti-mouse immunoglobulin antibody confirmed that the two MAbs reacted with the same or structurally very similar glycolipids.

Technology transfer of an oil-in-water vaccine-adjuvant for strengthening pandemic influenza preparedness in Indonesia.

With the current enzootic circulation of highly pathogenic avian influenza viruses, the ability to increase global pandemic influenza vaccine production capacity is of paramount importance. This has been highlighted by, and is one of the main pillars of, the WHO Global Action Plan for Influenza Vaccines (GAP). Such capacity expansion is especially relevant in developing countries. The Vaccine Formulation Laboratory at University of Lausanne is engaged in the technology transfer of an antigen-sparing oil-in-water adjuvant in order to empower developing countries vaccine manufacturers to increase pandemic influenza vaccine capacity. In a one-year project funded by United States Department of Health and Human Services, the Vaccine Formulation Laboratory transferred the process know-how and associated equipment for the pilot-scale manufacturing of an oil-in-water adjuvant to Bio Farma, Indonesia's state-owned vaccine manufacturer, for subsequent formulation with H5N1 pandemic influenza vaccines. This paper describes the experience acquired and lessons learnt from this technology transfer project.

Thymic lineage commitment rather than selection causes genetic variations in size of CD4 and CD8 compartments.

During their development, immature CD4+ CD8+ thymocytes become committed to either the CD4 or CD8 lineage. Subsequent complete maturation of CD4+ and CD8+ cells requires a molecular match of the expressed coreceptor and the MHC specificity of the TCR. The final size of the mature CD4+ and CD8+ thymic compartments is therefore determined by a combination of lineage commitment and TCR-mediated selection. In humans and mice, the relative size of CD4+ and CD8+ peripheral T cell compartments shows marked genetic variability. We show here that genetic variations in thymic lineage commitment, rather than TCR-mediated selection processes, are responsible for the distinct CD4/CD8 ratios observed in common inbred mouse strains. Genetic variations in the regulation of lineage commitment open new ways to analyze this process and to identify the molecules involved.

The role of the T-cell receptor (TCR) in alpha beta/gamma delta lineage commitment: clues from intracellular TCR staining.

T cells belong to two mutually exclusive lineages expressing either alpha beta or gamma delta T-cell receptors (TCR). Although alpha beta and gamma delta cells are known to share a common precursor the role of TCR rearrangement and specificity in the lineage commitment process is controversial. Instructive lineage commitment models endow the alpha beta or gamma delta TCR with a deterministic role in lineage choice, whereas separate lineage models invoke TCR-independent lineage commitment followed by TCR-dependent selection and maturation of alpha beta and gamma delta cells. Here we review the published data pertaining to the role of the TCR in alpha beta/gamma delta lineage commitment and provide some additional information obtained from recent intracellular TCR staining studies. We conclude that a variant of the separate lineage model is best able to accommodate all of the available experimental results.

Long-term outcomes of pandemic 2009 influenza A(H1N1)-associated severe ARDS.

BACKGROUND: No data on long-term outcomes of survivors of 2009 influenza A(H1N1) (A[H1N1])-associated ARDS are available. The objective of this study was to compare the 1-year outcomes of survivors of A(H1N1)-associated ARDS, according to use or no use of extracorporeal lung assist (ECLA), using its need as an ARDS severity surrogate. METHODS: Survivors of ARDS (12 with ECLA use vs 25 without, corresponding to 75% and 54% of the eligible patients for each group, respectively) selected from the Réseau Européen de Ventilation Artificielle (REVA) registry had previously been healthy, with only pregnancy and/or moderate obesity (BMI ≤ 35 kg/m²) as known risk factors for A(H1N1) infection. Lung function and morphology, health-related quality of life (HRQoL), and psychologic impairment were evaluated. RESULTS: At 1 year post-ICU discharge for the ECLA and no-ECLA groups, respectively, 50% and 40% reported significant exertion dyspnea, 83% and 64% had returned to work, and 75% and 64% had decreased diffusion capacity across the blood-gas barrier, despite their near-normal and similar lung function test results. For both groups, exercise test results showed diminished but comparable exercise capacities, with similar alveolar-arterial oxygen gradients at peak exercise, and CT scans showed minor abnormal findings. HRQoL assessed by the 36-Item Short-Form Health Survey was poorer for both groups than for a sex- and age-matched general population group, but without between-group differences. ECLA and no-ECLA group patients, respectively, had symptoms of anxiety (50% and 56%) and depression (28% and 28%) and were at risk for posttraumatic stress disorder (41% and 44%). CONCLUSIONS: One year post-ICU discharge, a majority of survivors of A(H1N1)-associated ARDS had minor lung disabilities with diminished diffusion capacities across the blood-gas barrier, and most had psychologic impairment and poorer HRQoL than a sex- and age-matched general population group. ECLA and no-ECLA group patients had comparable outcomes. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01271842; URL: www.clinicaltrials.gov

Lineage potential, plasticity and environmental reprogramming of epithelial stem/progenitor cells.

Recent evidence supports and reinforces the concept that environmental cues may reprogramme somatic cells and change their natural fate. In the present review, we concentrate on environmental reprogramming and fate potency of different epithelial cells. These include stratified epithelia, such as the epidermis, hair follicle, cornea and oesophagus, as well as the thymic epithelium, which stands alone among simple and stratified epithelia, and has been shown recently to contain stem cells. In addition, we briefly discuss the pancreas as an example of plasticity of intrinsic progenitors and even differentiated cells. Of relevance, examples of plasticity and fate change characterize pathologies such as oesophageal metaplasia, whose possible cell origin is still debated, but has important implications as a pre-neoplastic event. Although much work remains to be done in order to unravel the full potential and plasticity of epithelial cells, exploitation of this phenomenon has already entered the clinical arena, and might provide new avenues for future cell therapy of these tissues.

The role of Notch signaling during hematopoietic lineage commitment.

Over the last few years a vast amount of progress has been made in identifying mechanisms controlling lineage commitment and plasticity of hematopoietic precursors to different lymphoid or myeloid lineages. This has been due largely to the ability to identify and isolate rare cell populations in order to investigate their developmental potential, together with the development of inducible and/or tissue specific targeting technology. One family of proteins that has been postulated to be involved in hematopoietic stem cell maintenance as well as in multiple commitment processes during T cell development is the Notch receptors and their ligands. In this review we will summarize recent findings and controversies regarding the role of Notch signaling in the myeloid and lymphoid systems.

Dynamic social representations of the 2009 H1N1 pandemic: Shifting patterns of sense-making and blame

We investigate dynamics of public perceptions of the 2009 H1N1 influenza pandemic to understand changing patterns of sense-making and blame regarding the outbreak of emerging infectious diseases. We draw on social representation theory combined with a dramaturgical perspective to identify changes in how various collectives are depicted over the course of the pandemic, according to three roles: heroes, villains and victims. Quantitative results based on content analysis of three cross-sectional waves of interviews show a shift from mentions of distant collectives (e.g., far-flung countries) at Wave 1 to local collectives (e.g., risk groups) as the pandemic became of more immediate concern (Wave 2) and declined (Wave 3). Semi-automated content analysis of media coverage shows similar results. Thematic analyses of the discourse associated with collectives revealed that many were consistently perceived as heroes, villains and victims.