Population genomic evidence that human and animal infections in Africa come from the same populations of Dracunculus medinensis

BACKGROUND

Guinea worm-Dracunculus medinensis-was historically one of the major parasites of humans and has been known since antiquity. Now, Guinea worm is on the brink of eradication, as efforts to interrupt transmission have reduced the annual burden of disease from millions of infections per year in the 1980s to only 54 human cases reported globally in 2019. Despite the enormous success of eradication efforts to date, one complication has arisen. Over the last few years, hundreds of dogs have been found infected with this previously apparently anthroponotic parasite, almost all in Chad. Moreover, the relative numbers of infections in humans and dogs suggests that dogs are currently the principal reservoir on infection and key to maintaining transmission in that country.

PRINCIPAL FINDINGS

In an effort to shed light on this peculiar epidemiology of Guinea worm in Chad, we have sequenced and compared the genomes of worms from dog, human and other animal infections. Confirming previous work with other molecular markers, we show that all of these worms are D. medinensis, and that the same population of worms are causing both infections, can confirm the suspected transmission between host species and detect signs of a population bottleneck due to the eradication efforts. The diversity of worms in Chad appears to exclude the possibility that there were no, or very few, worms present in the country during a 10-year absence of reported cases.

CONCLUSIONS

This work reinforces the importance of adequate surveillance of both human and dog populations in the Guinea worm eradication campaign and suggests that control programs aiming to interrupt disease transmission should stay aware of the possible emergence of unusual epidemiology as pathogens approach elimination.

Genomic analysis of natural intra-specific hybrids among Ethiopian isolates of Leishmania donovani

Parasites of the genus Leishmania (Kinetoplastida: Trypanosomatidae) cause widespread and devastating human diseases. Visceral leishmaniasis due to Leishmania donovani is endemic in Ethiopia where it has also been responsible for major epidemics. The presence of hybrid genotypes has been widely reported in surveys of natural populations, genetic variation reported in a number of Leishmania species, and the extant capacity for genetic exchange demonstrated in laboratory experiments. However, patterns of recombination and the evolutionary history of admixture that produced these hybrid populations remain unclear. Here, we use whole-genome sequence data to investigate Ethiopian L. donovani isolates previously characterized as hybrids by microsatellite and multi-locus sequencing. To date there is only one previous study on a natural population of Leishmania hybrids based on whole-genome sequences. We propose that these hybrids originate from recombination between two different lineages of Ethiopian L. donovani occurring in the same region. Patterns of inheritance are more complex than previously reported with multiple, apparently independent, origins from similar parents that include backcrossing with parental types. Analysis indicates that hybrids are representative of at least three different histories. Furthermore, isolates were highly polysomic at the level of chromosomes with differences between parasites recovered from a recrudescent infection from a previously treated individual. The results demonstrate that recombination is a significant feature of natural populations and contributes to the growing body of data that shows how recombination, and gene flow, shape natural populations of Leishmania.

Global genome diversity of the Leishmania donovani complex

Protozoan parasites of the Leishmania donovani complex - L. donovani and L. infantum - cause the fatal disease visceral leishmaniasis. We present the first comprehensive genome-wide global study, with 151 cultured field isolates representing most of the geographical distribution. L. donovani isolates separated into five groups that largely coincide with geographical origin but vary greatly in diversity. In contrast, the majority of L. infantum samples fell into one globally-distributed group with little diversity. This picture is complicated by several hybrid lineages. Identified genetic groups vary in heterozygosity and levels of linkage, suggesting different recombination histories. We characterise chromosome-specific patterns of aneuploidy and identified extensive structural variation, including known and suspected drug resistance loci. This study reveals greater genetic diversity than suggested by geographically-focused studies, provides a resource of genomic variation for future work and sets the scene for a new understanding of the evolution and genetics of the Leishmania donovani complex.

Population genetic analysis of Chadian Guinea worms reveals that human and non-human hosts share common parasite populations

Following almost 10 years of no reported cases, Guinea worm disease (GWD or dracunculiasis) reemerged in Chad in 2010 with peculiar epidemiological patterns and unprecedented prevalence of infection among non-human hosts, particularly domestic dogs. Since 2014, animal infections with Guinea worms have also been observed in the other three countries with endemic transmission (Ethiopia, Mali, and South Sudan), causing concern and generating interest in the parasites' true taxonomic identity and population genetics. We present the first extensive population genetic data for Guinea worm, investigating mitochondrial and microsatellite variation in adult female worms from both human and non-human hosts in the four endemic countries to elucidate the origins of Chad's current outbreak and possible host-specific differences between parasites. Genetic diversity of Chadian Guinea worms was considerably higher than that of the other three countries, even after controlling for sample size through rarefaction, and demographic analyses are consistent with a large, stable parasite population. Genealogical analyses eliminate the other three countries as possible sources of parasite reintroduction into Chad, and sequence divergence and distribution of genetic variation provide no evidence that parasites in human and non-human hosts are separate species or maintain isolated transmission cycles. Both among and within countries, geographic origin appears to have more influence on parasite population structure than host species. Guinea worm infection in non-human hosts has been occasionally reported throughout the history of the disease, particularly when elimination programs appear to be reaching their end goals. However, no previous reports have evaluated molecular support of the parasite species identity. Our data confirm that Guinea worms collected from non-human hosts in the remaining endemic countries of Africa are Dracunculus medinensis and that the same population of worms infects both humans and dogs in Chad. Our genetic data and the epidemiological evidence suggest that transmission in the Chadian context is currently being maintained by canine hosts.

HIV-1 Integrates Widely throughout the Genome of the Human Blood Fluke Schistosoma mansoni

Schistosomiasis is the most important helminthic disease of humanity in terms of morbidity and mortality. Facile manipulation of schistosomes using lentiviruses would enable advances in functional genomics in these and related neglected tropical diseases pathogens including tapeworms, and including their non-dividing cells. Such approaches have hitherto been unavailable. Blood stream forms of the human blood fluke, Schistosoma mansoni, the causative agent of the hepatointestinal schistosomiasis, were infected with the human HIV-1 isolate NL4-3 pseudotyped with vesicular stomatitis virus glycoprotein. The appearance of strong stop and positive strand cDNAs indicated that virions fused to schistosome cells, the nucleocapsid internalized and the RNA genome reverse transcribed. Anchored PCR analysis, sequencing HIV-1-specific anchored Illumina libraries and Whole Genome Sequencing (WGS) of schistosomes confirmed chromosomal integration; >8,000 integrations were mapped, distributed throughout the eight pairs of chromosomes including the sex chromosomes. The rate of integrations in the genome exceeded five per 1,000 kb and HIV-1 integrated into protein-encoding loci and elsewhere with integration bias dissimilar to that of human T cells. We estimated ~ 2,100 integrations per schistosomulum based on WGS, i.e. about two or three events per cell, comparable to integration rates in human cells. Accomplishment in schistosomes of post-entry processes essential for HIV-1replication, including integrase-catalyzed integration, was remarkable given the phylogenetic distance between schistosomes and primates, the natural hosts of the genus Lentivirus. These enigmatic findings revealed that HIV-1 was active within cells of S. mansoni, and provided the first demonstration that HIV-1 can integrate into the genome of an invertebrate.

Assessing current genetic status of the Hainan gibbon using historical and demographic baselines: implications for conservation management of species of extreme rarity

Evidence-based conservation planning is crucial for informing management decisions for species of extreme rarity, but collection of robust data on genetic status or other parameters can be extremely challenging for such species. The Hainan gibbon, possibly the world's rarest mammal, consists of a single population of ~25 individuals restricted to one protected area on Hainan Island, China, and has persisted for over 30 years at exceptionally low population size. Analysis of genotypes at 11 microsatellite loci from faecal samples for 36% of the current global population and tissue samples from 62% of existing historical museum specimens demonstrates limited current genetic diversity (Na = 2.27, Ar = 2.24, He  = 0.43); diversity has declined since the 19th century and even further within the last 30 years, representing declines of ~30% from historical levels (Na = 3.36, Ar = 3.29, He  = 0.63). Significant differentiation is seen between current and historical samples (FST  = 0.156, P = 0.0315), and the current population exhibits extremely small Ne (current Ne  = 2.16). There is evidence for both a recent population bottleneck and an earlier bottleneck, with population size already reasonably low by the late 19th century (historical Ne  = 1162.96). Individuals in the current population are related at the level of half- to full-siblings between social groups, and full-siblings or parent-offspring within a social group, suggesting that inbreeding is likely to increase in the future. The species' current reduced genetic diversity must be considered during conservation planning, particularly for expectations of likely population recovery, indicating that intensive, carefully planned management is essential.

Susceptibility to Klebsiella pneumonaie infection in collaborative cross mice is a complex trait controlled by at least three loci acting at different time points

BACKGROUND

Klebsiella pneumoniae (Kp) is a bacterium causing severe pneumonia in immunocompromised hosts and is often associated with sepsis. With the rise of antibiotic resistant bacteria, there is a need for new effective and affordable control methods; understanding the genetic architecture of susceptibility to Kp will help in their development. We performed the first quantitative trait locus (QTL) mapping study of host susceptibility to Kp infection in immunocompetent Collaborative Cross mice (CC). We challenged 328 mice from 73 CC lines intraperitoneally with 104 colony forming units of Kp strain K2. Survival and body weight were monitored for 15 days post challenge. 48 of the CC lines were genotyped with 170,000 SNPs, with which we mapped QTLs.

RESULTS

CC lines differed significantly (P < 0.05) in mean survival time, between 1 to 15 days post infection, and broad sense heritability was 0.45. Distinct QTL were mapped at specific time points during the challenge. A QTL on chromosome 4 was found only on day 2 post infection, and QTL on chromosomes 8 and 18, only on day 8. By using the sequence variations of the eight inbred strain founders of the CC to refine QTL localization we identify several candidate genes.

CONCLUSION

Host susceptibility to Kp is a complex trait, controlled by multiple genetic factors that act sequentially during the course of infection.

Host Susceptibility to Periodontitis

Host susceptibility to periodontal infection is controlled by genetic factors. As a step toward identifying and cloning these factors, we generated an A/J x BALB/cJ F2 mouse resource population. A genome-wide search for Quantitative Trait Loci (QTL) associated with periodontitis was performed. We aimed to quantify the phenotypic response of the progenies to periodontitis by microCT analysis, to perform a genome-wide search for QTL associated with periodontitis, and, finally, to suggest candidate genes for periodontitis. We were able to produce 408 F2 mice. All mice were co-infected with Porphyromonas gingivalis and Fusobacterium nucleatum bacteria. Six weeks following infection, alveolar bone loss was quantified by computerized tomography (microCT) technology. We found normal distribution of the phenotype, with 2 highly significant QTL on chromosomes 5 and 3. A third significant QTL was found on chromosome 1. Candidate genes were suggested, such as Toll-like receptors (TLR) 1 and 6, chemokines, and bone-remodeling genes (enamelin, ameloblastin, and amelotin). This report shows that periodontitis in mice is a polygenic trait with highly significant mapped QTL.

Bioinformatics tools and database resources for systems genetics analysis in mice--a short review and an evaluation of future needs

During a meeting of the SYSGENET working group ‘Bioinformatics’, currently available software tools and databases for systems genetics in mice were reviewed and the needs for future developments discussed. The group evaluated interoperability and performed initial feasibility studies. To aid future compatibility of software and exchange of already developed software modules, a strong recommendation was made by the group to integrate HAPPY and R/qtl analysis toolboxes, GeneNetwork and XGAP database platforms, and TIQS and xQTL processing platforms. R should be used as the principal computer language for QTL data analysis in all platforms and a ‘cloud’ should be used for software dissemination to the community. Furthermore, the working group recommended that all data models and software source code should be made visible in public repositories to allow a coordinated effort on the use of common data structures and file formats.

Pervasive haplotypic variation in the spliceo-transcriptome of the human major histocompatibility complex

The human major histocompatibility complex (MHC) on chromosome 6p21 is a paradigm for genomics, showing remarkable polymorphism and striking association with immune and non-immune diseases. The complex genomic landscape of the MHC, notably strong linkage disequilibrium, has made resolving causal variants very challenging. A promising approach is to investigate gene expression levels considered as tractable intermediate phenotypes in mapping complex diseases. However, how transcription varies across the MHC, notably relative to specific haplotypes, remains unknown. Here, using an original hybrid tiling and splice junction microarray that includes alternate allele probes, we draw the first high-resolution strand-specific transcription map for three common MHC haplotypes (HLA-A1-B8-Cw7-DR3, HLA-A3-B7-Cw7-DR15, and HLA-A26-B18-Cw5-DR3-DQ2) strongly associated with autoimmune diseases including type 1 diabetes, systemic lupus erythematosus, and multiple sclerosis. We find that haplotype-specific differences in gene expression are common across the MHC, affecting 96 genes (46.4%), most significantly the zing finger protein gene ZFP57. Differentially expressed probes are correlated with polymorphisms between haplotypes, consistent with cis effects that we directly demonstrate for ZFP57 in a cohort of healthy volunteers (P = 1.2 × 10(-14)). We establish that alternative splicing is significantly more frequent in the MHC than genome-wide (72.5% vs. 62.1% of genes, P ≤ 1 × 10(-4)) and shows marked haplotypic differences. We also unmask novel and abundant intergenic transcription involving 31% of transcribed blocks identified. Our study reveals that the renowned MHC polymorphism also manifests as transcript diversity, and our novel haplotype-based approach marks a new step toward identification of regulatory variants involved in the control of MHC-associated phenotypes and diseases.

Collaborative Cross mice and their power to map host susceptibility to Aspergillus fumigatus infection

The Collaborative Cross (CC) is a genetic reference panel of recombinant inbred lines of mice, designed for the dissection of complex traits and gene networks. Each line is independently descended from eight genetically diverse founder strains such that the genomes of the CC lines, once fully inbred, are fine-grained homozygous mosaics of the founder haplotypes. We present an analysis of 120 CC lines, from a cohort of the CC bred at Tel Aviv University in collaboration with the University of Oxford, which at the time of this study were between the sixth and 12th generations of inbreeding and substantially homozygous at 170,000 SNPs. We show how CC genomes decompose into mosaics, and we identify loci that carry a deficiency or excess of a founder, many being deficient for the wild-derived strains WSB/EiJ and PWK/PhJ. We phenotyped 371 mice from 66 CC lines for a susceptibility to Aspergillus fumigatus infection. The survival time after infection varied significantly between CC lines. Quantitative trait locus (QTL) mapping identified genome-wide significant QTLs on chromosomes 2, 3, 8, 10 (two QTLs), 15, and 18. Simulations show that QTL mapping resolution (the median distance between the QTL peak and true location) varied between 0.47 and 1.18 Mb. Most of the QTLs involved contrasts between wild-derived founder strains and therefore would not segregate between classical inbred strains. Use of variation data from the genomes of the CC founder strains refined these QTLs further and suggested several candidate genes. These results support the use of the CC for dissecting complex traits.

Genetic analysis of complex traits in the emerging Collaborative Cross

The Collaborative Cross (CC) is a mouse recombinant inbred strain panel that is being developed as a resource for mammalian systems genetics. Here we describe an experiment that uses partially inbred CC lines to evaluate the genetic properties and utility of this emerging resource. Genome-wide analysis of the incipient strains reveals high genetic diversity, balanced allele frequencies, and dense, evenly distributed recombination sites-all ideal qualities for a systems genetics resource. We map discrete, complex, and biomolecular traits and contrast two quantitative trait locus (QTL) mapping approaches. Analysis based on inferred haplotypes improves power, reduces false discovery, and provides information to identify and prioritize candidate genes that is unique to multifounder crosses like the CC. The number of expression QTLs discovered here exceeds all previous efforts at eQTL mapping in mice, and we map local eQTL at 1-Mb resolution. We demonstrate that the genetic diversity of the CC, which derives from random mixing of eight founder strains, results in high phenotypic diversity and enhances our ability to map causative loci underlying complex disease-related traits.

Gene X environment interactions at the serotonin transporter locus

BACKGROUND

Although it is universally accepted that human disease and behavior depend upon both environmental and genetic variation, a view supported by family and twin studies, examples of environmental interactions with genes identified at the molecular level (G x E) are not so well established.

METHODS

We carried out a systematic review and meta-analysis of the serotonin transporter (5-HTTLPR) polymorphic region x stressful life event (SLE) literature and investigated to what extent the main effects reported in this literature are consistent with a number of G x E hypotheses. Our aim was to provide a framework in which to assess the robustness of the claim for the presence of an interaction.

RESULTS

The results from our systematic review and meta-analysis indicate that the main effect of 5-HTTLPR genotype and the interaction effect between 5-HTTLPR and SLE on risk of depression are negligible. We found that only a minority of studies report a replication that is qualitatively comparable to that in the original report.

CONCLUSIONS

Given reasonable assumptions regarding likely genetic and environmental effect sizes, our simulations indicate that published studies are underpowered. This, together with other aspects of the literature, leads us to suggest that the positive results for the 5-HTTLPR x SLE interactions in logistic regression models are compatible with chance findings.

Analysis of the rainbow trout solute carrier 11 family reveals iron import < or = pH 7.4 and a functional isoform lacking transmembrane domains 11 and 12

A Xenopus oocyte heterologous expression system was used to characterise iron transport properties of two members of the solute carrier 11 (slc11) protein family isolated from rainbow trout gills. One cDNA clone differed from the trout Slc11alpha containing an additional 52bp in the exon between transmembrane domains (TM) 10 and 11. The 52bp contained a stop codon, resulting in a novel isoform lacking the last two TM (termed slc11gamma). Slc11gamma and another isoform slc11beta, import Fe(2+) at external pHs < or = to 7.4. Trout slc11beta Fe(2+) import was more sensitive to inhibition by divalent metals. The novel vertebrate slc11gamma isoform functions without TM11 and 12.

Forgotten digital tourniquet: salvage of an ischaemic finger by application of medicinal leeches

Individual finger tourniquets are appropriate to the management of a wide range of conditions presenting to an accident and emergency department. They are simpler and more comfortable to use than upper arm pneumatic tourniquets and commercially available digital tourniquets are not readily available in the accident and emergency unit. However, if a finger tourniquet is overlooked, ischaemia of the digit results, and gangrene may follow if the problem is not defused early enough, leading to potential disaster. We present one case where a digit was salvaged after 4 days of tourniquet application, using medicinal leeches.

The rapid identification of human influenza neuraminidase N1 and N2 subtypes by ELISA

An ELISA assay was developed to allow the rapid and accurate identification of human influenza A N1 and N2 neuraminidases. Initial testing using a fetuin pre-coating of wells correctly identified 81.7% of the neuraminidase type from a series of human A(H1N1), A(H1N2) and A(H3N2) viruses. This result could be improved to detect the neuraminidase subtype of almost all human influenza A viruses from a large panel of viruses isolated from 2000 to 2005, if the fetuin pre-coating was removed and the viruses were coated directly onto wells. This method is simple, rapid and can be used to screen large numbers of currently circulating human influenza A viruses for their neurraminidase subtype and is a good alternative to RT-PCR.

Linkage disequilibrium mapping via cladistic analysis of phase-unknown genotypes and inferred haplotypes in the Genetic Analysis Workshop 14 simulated data

We recently described a method for linkage disequilibrium (LD) mapping, using cladistic analysis of phased single-nucleotide polymorphism (SNP) haplotypes in a logistic regression framework. However, haplotypes are often not available and cannot be deduced with certainty from the unphased genotypes. One possible two-stage approach is to infer the phase of multilocus genotype data and analyze the resulting haplotypes as if known. Here, haplotypes are inferred using the expectation-maximization (EM) algorithm and the best-guess phase assignment for each individual analyzed. However, inferring haplotypes from phase-unknown data is prone to error and this should be taken into account in the subsequent analysis. An alternative approach is to analyze the phase-unknown multilocus genotypes themselves. Here we present a generalization of the method for phase-known haplotype data to the case of unphased SNP genotypes. Our approach is designed for high-density SNP data, so we opted to analyze the simulated dataset. The marker spacing in the initial screen was too large for our method to be effective, so we used the answers provided to request further data in regions around the disease loci and in null regions. Power to detect the disease loci, accuracy in localizing the true site of the locus, and false-positive error rates are reported for the inferred-haplotype and unphased genotype methods. For this data, analyzing inferred haplotypes outperforms analysis of genotypes. As expected, our results suggest that when there is little or no LD between a disease locus and the flanking region, there will be no chance of detecting it unless the disease variant itself is genotyped.

An influenza A(H3) reassortant was epidemic in Australia and New Zealand in 2003

During 2003, Australia and New Zealand experienced substantial outbreaks of influenza. The strain responsible was an A(H3N2) influenza virus described as A/Fujian/411/2002-like, which had circulated as a minor variant in the previous Northern Hemisphere (NH) winter, mainly in Korea and Japan. Early in the year the isolates were very similar to those that had been previously isolated in the NH, however, a reassortant strain emerged early in the New Zealand winter, followed by the appearance of similar viruses in Australia and other regional areas. While the hemagglutinin HA1 sequence of these viruses demonstrated only minor differences from the A/Fujian/411/2002 reference strain, the neuraminidase gene was clearly different from that of other recently circulating H3 viruses and most closely matched an earlier reference strain A/Chile/6416/2001. Three internal genes (NS, NP, M) in the reassortant viruses were also more closely related to the A/Chile/6416/2001 lineage. This reassortant A(H3) virus predominated in Australia and New Zealand in 2003 was also seen in Brazil and Malaysia during 2003 and was widespread in the United States and Europe during their 2003-04 winter. Interestingly most of the strains of A(H3) that were isolated at the beginning of the 2004 winter in Australia, did not have this earlier A/Chile/6416/2001-like neuraminidase but had a neuraminidase that was similar to that of the reference strain A/Fujian/411/2002. This was suggestive of the re-introduction of influenza A(H3) from other countries, however, there was still low level circulation of the reassortant virus in 2004 with isolates detected in Australia and Singapore.

Efficiency and consistency of haplotype tagging of dense SNP maps in multiple samples

Haplotype tagging is a means of retaining most of the information in high density marker maps, while reducing genotyping requirements. Estimates of the numbers of tagging SNPs required to cover the human genome have varied widely, ranging from 100,000 to 1,000,000. Tagging has been applied to a number of gene-based datasets but has not been evaluated in contexts reflecting those of genome-wide association studies--large chromosome regions and multiple samples drawn from the same population. We analysed 5000 common markers across a 10 Mb segment of human chromosome 20 in three samples (UK Caucasian, CEPH Caucasian, African American) to evaluate tagging efficiency and consistency. Overall, the results indicate a high degree of efficiency, yielding 3-5-fold savings in Caucasians and 2-3-fold savings in African Americans. These levels varied according to linkage disequilibrium (LD) levels, tagging thresholds and allele frequencies, but in high LD regions they did not vary markedly due to marker density. However, a strong positive relationship between marker density and tagging was observed, relating to the fact that increasing marker density yields greater sequence coverage in high LD, thus requiring more tag SNPs to cover a greater fraction of the genome. Encouragingly, whatever the density employed, a high level of robustness was observed between UK and CEPH samples, as most of the htSNPs selected in one sample were also appropriate as tags in the other.

Linkage disequilibrium mapping via cladistic analysis of single-nucleotide polymorphism haplotypes

We present a novel approach to disease-gene mapping via cladistic analysis of single-nucleotide polymorphism (SNP) haplotypes obtained from large-scale, population-based association studies, applicable to whole-genome screens, candidate-gene studies, or fine-scale mapping. Clades of haplotypes are tested for association with disease, exploiting the expected similarity of chromosomes with recent shared ancestry in the region flanking the disease gene. The method is developed in a logistic-regression framework and can easily incorporate covariates such as environmental risk factors or additional unlinked loci to allow for population structure. To evaluate the power of this approach to detect disease-marker association, we have developed a simulation algorithm to generate high-density SNP data with short-range linkage disequilibrium based on empirical patterns of haplotype diversity. The results of the simulation study highlight substantial gains in power over single-locus tests for a wide range of disease models, despite overcorrection for multiple testing.

Reassortants in recent human influenza A and B isolates from South East Asia and Oceania

From 2000 to 2002, human influenza A and B viruses that were genetic reassortants of contemporary circulating human strains, were isolated in South East Asia and Oceania. Similar to reports from other regions, A(H1N2) isolates were found to be reassortants of circulating A(H3N2) viruses that had acquired only the haemagglutinin gene of an A(H1N1) virus. Some of these reassortants from Thailand and Singapore predate those previously recorded during the winter of 2001-2002 in Europe and the Middle East and may be precursors of these viruses. The B reassortants had a haemagglutinin similar to an earlier B strain, B/Shangdong/7/97 (B/Victoria/2/87-lineage) and a neuraminidase similar to the recently circulating B/Sichuan/379/99 virus (B/Yamagata/16/88-lineage). Despite the early occurrences of A(H1N2) reassortants and the extensive circulation of A(H1) viruses in South East Asia and Oceania during 2000-2001, these reassortant influenza A viruses have to date not been prominent unlike Europe and the Middle East where they were common in the 2001-2002 winter. In contrast the reassortant B viruses, which first emerged in this region in early 2002, rapidly became the predominant strains isolated from patients with influenza B in South East Asia and Oceania.

The responsibility of the pharmaceutical industry

The pharmaceutical industry plays an active role in policy surrounding the research, discovery and development of new medicines. Along with this commitment, the pharmaceutical industry must also take an active role in helping to ensure that appropriate patients receive access to state-of-the-art scientific advancements. The various players involved in drug development and introduction, including the pharmaceutical industry, clinicians, advocacy groups and regulatory bodies, need to work together to ensure patient access to quality care. While issues such as drug acquisition costs and marketing are often given a high profile, this may cloud perceptions of the industry's commitment to deliver important new medicines to the patients and healthcare systems that need them.

Analytical Solutions and Simulations for Spin-Echo Measurements of Diffusion of Spins in a Sphere with Surface and Bulk Relaxation

Nuclear spins (in molecules) are considered to be diffusing in a sphere in a linearly inhomogeneous magnetic field (field gradient) that is imposed during a spin-echo NMR experiment. Relaxation of magnetization both in the bulk medium and on the inner surface of the sphere is assumed to occur. Analytical solutions were obtained for the relevant modified diffusion (partial differential) equation by using separation of variables with a Green's function (propagator) and three different boundary conditions. Neuman [J. Chem. Phys. 60, 4508 (1974)] analyzed the same physical system, but with no relaxation, to obtain an expression that relates the NMR spin-echo signal intensity to the magnitude of the magnetic field gradient, the spin-echo time, and the intrinsic molecular diffusion coefficient. The present analysis was based on that originally used by Neuman and, like the latter, it employed the assumption of a Gaussian distribution of phases of the spin magnetizations. This assumption, while rendering a tractable solution, nevertheless limits its range of applicability; this aspect, and the convergence properties of the series solutions were investigated in conjunction with numerical simulations made with diffusion modeled as a three-dimensional random (Monte Carlo) walk. A novel prediction for spheres with finite surface relaxation and a given radius is the presence of two minima in a graph of the normalized spin-echo signal intensity versus the reciprocal of the diffusion coefficient.

Prophylactic efficacy of aerosolized liposomal (AmBisome) and non-liposomal (Fungizone) amphotericin B in murine pulmonary aspergillosis

Pulmonary aspergillosis is a serious opportunistic disease in patients with immune suppression. Prophylactic measures would be highly beneficial because treatment often fails after infection occurs. The principle objective of this study was to evaluate the prophylactic efficacy of aerosolized liposomal (AmBisome) and non-liposomal (Fungizone) amphotericin B in a murine model. Immunocompromised mice were treated prophylactically for 3 days with AmBisome or Fungizone using a small particle aerosol generator. Intranasal challenge was with a high (10(8)), medium (10(7)), or low (10(6)) level of Aspergillus fumigatus spores. AmBisome nebulized more uniformly, resulting in very consistent chamber air concentrations. Total dose, however, was nearly the same for each formulation. Survival was prolonged in animals treated with both formulations at the 10(8) and 10(7) challenge levels. Quantitative lung cultures showed that organisms were completely cleared from the lungs in the low challenged group, with both formulations, whereas the high challenge proved overwhelming for both formulations. With the middle challenge, however, AmBisome cleared 80% of the lungs, whereas Fungizone cleared none. Lung drug retention of AmBisome treated animals was more than eight times higher than Fungizone at the time of challenge. BUN and creatinine values in animals treated with both formulations were not elevated. These results suggest that AmBisome is more effective than Fungizone when given as a prophylactic aerosol in this model.

The effect of a high intake of calcium and phosphate in normal subjects and patients with chronic renal failure

1. Two normal subjects and ten patients with chronic renal failure were given 15 or 20 g of calcium carbonate in the morning and 5·6 or 8·4 g of calcium phosphate in the evening for 13–41 days.

2. During the high calcium and phosphate intake there was a rise in calcium and phosphate absorption from the gut in the normal subjects and to about the same extent in the patients with chronic renal failure.

3. The calcium and phosphate balances became positive while there was a rise in plasma calcium and a fall in plasma phosphate. There was also a fall in urinary phosphate excretion.