Pedigree with frontotemporal lobar degeneration – motor neuron disease and Tar DNA binding protein-43 positive neuropathology: genetic linkage to chromosome 9

Background

Frontotemporal lobar degeneration (FTLD) represents a clinically, pathologically and genetically heterogenous neurodegenerative disorder, often complicated by neurological signs such as motor neuron-related limb weakness, spasticity and paralysis, parkinsonism and gait disturbances. Linkage to chromosome 9p had been reported for pedigrees with the neurodegenerative disorder, frontotemporal lobar degeneration (FTLD) and motor neuron disease (MND). The objective in this study is to identify the genetic locus in a multi-generational Australian family with FTLD-MND.

Methods

Clinical review and standard neuropathological analysis of brain sections from affected pedigree members. Genome-wide scan using microsatellite markers and single nucleotide polymorphism fine mapping. Examination of candidate genes by direct DNA sequencing.

Results

Neuropathological examination revealed cytoplasmic deposition of the TDP-43 protein in three affected individuals. Moreover, we identify a family member with clinical Alzheimer's disease, and FTLD-Ubiquitin neuropathology. Genetic linkage and haplotype analyses, defined a critical region between markers D9S169 and D9S1845 on chromosome 9p21. Screening of all candidate genes within this region did not reveal any novel genetic alterations that co-segregate with disease haplotype, suggesting that one individual carrying a meiotic recombination may represent a phenocopy. Re-analysis of linkage data using the new affection status revealed a maximal two-point LOD score of 3.24 and a multipoint LOD score of 3.41 at marker D9S1817. This provides the highest reported LOD scores from a single FTLD-MND pedigree.

Conclusion

Our reported increase in the minimal disease region should inform other researchers that the chromosome 9 locus may be more telomeric than predicted by published recombination boundaries. Moreover, the existence of a family member with clinical Alzheimer's disease, and who shares the disease haplotype, highlights the possibility that late-onset AD patients in the other linked pedigrees may be mis-classified as sporadic dementia cases.     

Investigation of the diurnal variation in bone resorption for optimal drug delivery and efficacy in osteoporosis with oral calcitonin

Background  

Bone resorption displays marked diurnal variation. Reversible inhibition of bone resorption may result in best possible efficacy when bone resorption peaks. The aim of the study was to assess the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of 0.8 mg of oral salmon calcitonin (sCT) and the effect of timing of drug intake.     

Human immunodeficiency virus seroconversion presenting with acute inflammatory demyelinating polyneuropathy: a case report

Introduction

Electrocardiogram (ECG) abnormalities in patients with blunt chest trauma are diverse and non-specific, but may be indicative of potentially life-threatening conditions.

Case presentation

We report a rare case of pneumopericardium with extreme ECG abnormalities after blunt chest trauma in a 22-year-old male. The diagnosis was confirmed using computed tomography (CT) scanning. The case is discussed, together with its differential diagnosis and the aetiology of pneumopericardium and tension pneumopericardium.

Conclusion

Pneumopericardium should be distinguished from other pathologies such as myocardial contusion and myocardial infarction because of the possible development of tension pneumopericardium. Early CT scanning is important in the evaluation of blunt chest trauma.     

Genetic differentiation in the urban habitat: the great tits (Parus major) of the parks of Barcelona city

The increase of urban areas has led to a fragmentation of habitats for many forest‐living species. Man‐made parks might be a solution, but they can also act as sinks that are unable to maintain themselves without immigration from natural areas. Alternatively, parks might act as true metapopulations with extinctions and colonizations. In both cases, we can expect genetic variation to be reduced in the parks compared to the natural habitat. A third alternative is that the parks have sufficient reproduction to maintain themselves. To test these hypotheses, we analysed the pattern of genetic variation in the great tit (Parus major) in 12 parks in central Barcelona, and in an adjacent forest population using microsatellites. Genetic variation was not lower in the parks compared to the forest population, but larger, and gene flow was higher from the town to the forest compared to vice versa. We found a significant genetic differentiation among the parks, with a structure that only partly reflected the geographic position of the parks. Relatedness among individuals within parks was higher than expected by chance, although we found no evidence of kin groups. Assignment tests suggest that some parks are acting as net donors of individuals to other parks. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 9–19.     

Extralymphoid CD8+ T Cells Resident in Tissue from Simian Immunodeficiency Virus SIVmac239Δnef-Vaccinated Macaques Suppress SIVmac239 Replication Ex Vivo

Live-attenuated vaccination with simian immunodeficiency virus (SIV) SIVmac239Δnef is the most successful vaccine product tested to date in macaques. However, the mechanisms that explain the efficacy of this vaccine remain largely unknown. We utilized an ex vivo viral suppression assay to assess the quality of the immune response in SIVmac239Δnef-immunized animals. Using major histocompatibility complex-matched Mauritian cynomolgus macaques, we did not detect SIV-specific functional immune responses in the blood by gamma interferon (IFN-γ) enzyme-linked immunospot assay at select time points; however, we found that lung CD8⁺ T cells, unlike blood CD8⁺ T cells, effectively suppress virus replication by up to 80%. These results suggest that SIVmac239Δnef may be an effective vaccine because it elicits functional immunity at mucosal sites. Moreover, these results underscore the limitations of relying on immunological measurements from peripheral blood lymphocytes in studies of protective immunity to HIV/SIV.Despite over 25 years of intensive research, efforts to develop a successful prophylactic HIV vaccine have failed (6, 39). The extraordinary difficulty of developing an HIV vaccine underscores the fact that the elements comprising an effective immune response directed against HIV are poorly understood. Simian immunodeficiency virus (SIV) infection of Mauritian cynomolgus macaques (MCM) provides the best model for unraveling the correlates of protection against SIV. With SIV infection of MCM, we can select the timing, route, dose, and sequence of the infecting virus. Additionally, the limited genetic diversity of MCM facilitates selection of genetically matched individuals that can be monitored throughout the acute phase of infection and enables more frequent and invasive sampling, especially of mucosal sites.Macaques infected with live-attenuated SIV, like SIVmac239Δnef, exhibit robust protection from pathogenic SIV infection (8, 10, 20, 25, 29, 35, 40, 44, 49, 53). While previous studies have included considerable heterogeneity in the strain of attenuated SIV, challenge strain, and macaque species used, they demonstrate collectively the broad spectrum of attenuated SIVs that effectively protect macaques against pathogenic challenge. Several studies have also shown that attenuated SIV effectively protects cynomolgus macaques against pathogenic challenge using an SIVmac239C8 virus (1-3). Like SIVmac239Δnef, this virus has a deletion in the nef gene, but this deletion is a considerably smaller 12-bp deletion than the 182-bp deletion in SIVmac239Δnef (24). Importantly, there are no studies that establish the protective efficacy of SIVmac239Δnef in MCM. Nevertheless, peak SIVmac239Δnef viral loads in MCM parallel the range established in rhesus macaques, between 3.2 × 10³ and 9.4 × 10⁵ (35), but fall below peak loads established in a separate study (8). The differences observed between the rhesus macaque study and our own could be due to differences in challenge dose. Long-term control of SIVmac239Δnef in MCM is also similar to that in rhesus macaques (35). It is critical to understand why live-attenuated SIV vaccines are so effective, with the ultimate goal of using these principals to develop a vaccine that is safe for use in humans.There are several plausible explanations for why live-attenuated SIV vaccines provide effective protection against challenge with pathogenic SIV. These explanations range from viral interference to a robust vaccine-elicited immune response (19, 43, 45, 47). We currently understand several aspects of live-attenuated vaccination with SIVmac239Δnef. First, there is an inverse relationship between the degree of attenuation and the level of protection (21). This relationship suggests that vigorous viral replication is important for the generation of an effective anti-SIV immune response. Second, the greater the sequence diversity between the vaccine strain and the challenge strain, the weaker is the protection provided by the vaccine (53). This demonstrates that an adaptive immune response that recognizes similar epitopes or virus features between the vaccine and challenge strains is necessary for protection in this model. Finally, vaccination with live-attenuated SIV requires a 15- to 20-week induction phase to achieve protection in the majority of animals (8). Thus, there is a direct relationship between the time postvaccination and the degree of protection between 0 and 20 weeks postvaccination. This temporal relationship suggests that a fully developed memory response is required to protect against pathogenic SIV challenge. Together, these observations argue that SIV-specific CD8⁺ T-lymphocyte responses might be important in protection as these responses would be less useful in the setting of heterologous virus challenge and require both robust viral replication and time to develop. Such responses, however, can be weak to nonexistent in the blood of vaccinated animals and frequently do not correlate with disease progression, leading some investigators to question their importance in protective immunity (25, 29, 45, 46). We hypothesize that continued replication of live-attenuated SIV in the mucosal tissues may lead to effective, compartmentalized memory T-cell responses that are important in controlling pathogenic SIV challenge.It is possible that prophylactic mucosal immunity is required to prevent viral replication soon after SIV infection and to minimize the destruction of mucosal immune cells that occurs within the first 3 weeks of SIV infection (9, 22, 26, 30). Initial depletion of effector memory CD4⁺ T cells in the gut-associated lymphoid tissue (GALT) combined with continuous viral replication leads to prolonged immune activation, eventual depletion of central memory CD4⁺ T cells, and the development of AIDS. An effective mucosal immune response elicited by live-attenuated SIV vaccination may prevent the initial CD4⁺ T-cell depletion from the gut. Several recent studies confirm a critical protective role for CD8⁺ T cells in the genital tract after vaccination with SHIV89.6, demonstrating that a mucosal immune response is capable of protecting against or ameliorating SIV infection (14-16, 48). Another study has also demonstrated the presence of high-frequency, polyfunctional T-cell responses in the mucosal tissues of elite controllers, i.e., individuals who maintain plasma viral loads below 75 copies/ml, compared to blood from the same individual, tissues of noncontrollers, and antiretroviral drug-treated patients. This study also provides a correlation between mucosal CD8⁺ T-cell responses and HIV control (12).While studying gut mucosal tissues is clearly an important part of understanding HIV/SIV pathology, there are several challenges to this undertaking. First, accessing gut tissues requires invasive sampling procedures, which are primarily limited to biopsy or time-of-death studies. Biopsies are often limited in number throughout the life span of an animal, while routine necropsy is cost-prohibitive for macaque studies. Second, these tissues are nonsterile. The digestive tract is teeming with floras that contaminate experiments requiring long-term cell culture. Finally, biopsies of mucosal tissues yield very few cells. These low cell numbers make ex vivo experiments very difficult or impossible to perform. Investigators have developed techniques to assess gut mucosal lymphocyte function by expanding these cells in vitro under sterile conditions with antibiotics and then using them in enzyme-linked immunospot assays (ELISPOT) or intracellular cytokine secretion (ICS) assays (18, 42). However, these experiments still suffer from two problems: (i) cells are altered in vitro, which may change their functional capacity; and, (ii) these experiments still rely on indirect measures of CD8⁺ T-cell function. These difficulties have limited research on mucosal CD8⁺ T-cell immunity during SIV infection.In light of these challenges, we decided to focus on the lung mucosal tissue, using CD8⁺ T cells isolated from bronchoalveolar lavage fluid (BAL). BAL samples lung mucosa where there are a large number of resident lymphocytes that encounter respiratory pathogens. Furthermore, BAL provides a minimally invasive sampling of a mucosal tissue that can be performed frequently, and BAL harbors effector T cells similar to GALT (32). These factors make the lung an ideal site for sampling mucosal CD8⁺ T cells.We modified an ex vivo viral suppression assay that tests the ability of CD8⁺ T cells to prevent viral replication in MCM (7, 27, 28, 36, 51, 54, 55). Using this approach, we compared the suppressive capacity of CD8⁺ T cells isolated from lung and blood, and we found that CD8⁺ T cells from the lung are more effective at suppressing viral replication than CD8⁺ T cells from the blood. This assay does not manipulate lung lymphocytes in vitro and provides a direct measure of CD8⁺ T-cell function. Furthermore, our data support the idea that CD8⁺ T cells in blood and mucosal tissue are not functionally equivalent, that blood lymphocytes are not a perfect surrogate for mucosal lymphocytes, and that mucosal T cells attenuate SIV replication to a greater extent than blood T cells.     

Competitive environments induce shifts in host fidelity

Recent models support the idea of sympatric speciation as a result of the joint effects of disruptive selection and assortative mating. We present experimental data, testing models of speciation through frequency‐dependent selection. We show that under high competition on a mixture of resources/hosts, strains of the Seed beetle, Callosobruchus maculatus, change their host fidelity and evolve a more generalistic behaviour in resource utilization among females. The change in host fidelity did not result in disruptive selection and was not followed by assortative mating. This means that only one of three fundamental prerequisites for sympatric speciation evolved as a result of the frequency‐dependent selection. We conclude that for this process to work, a shift to a novel food resource as a result of selection must also lead to a loss of preference for the original resource such that individuals are only able to use either one of the two.     

Local selection modifies phenotypic divergence among Rana temporaria populations in the presence of gene flow

In ectotherms, variation in life history traits among populations is common and suggests local adaptation. However, geographic variation itself is not a proof for local adaptation, as genetic drift and gene flow may also shape patterns of quantitative variation. We studied local and regional variation in means and phenotypic plasticity of larval life history traits in the common frog Rana temporaria using six populations from central Sweden, breeding in either open‐canopy or partially closed‐canopy ponds. To separate local adaptation from genetic drift, we compared differentiation in quantitative genetic traits (Q_ST) obtained from a common garden experiment with differentiation in presumably neutral microsatellite markers (F_ST). We found that R. temporaria populations differ in means and plasticities of life history traits in different temperatures at local, and in F_ST at regional scale. Comparisons of differentiation in quantitative traits and in molecular markers suggested that natural selection was responsible for the divergence in growth and development rates as well as in temperature‐induced plasticity, indicating local adaptation. However, at low temperature, the role of genetic drift could not be separated from selection. Phenotypes were correlated with forest canopy closure, but not with geographical or genetic distance. These results indicate that local adaptation can evolve in the presence of ongoing gene flow among the populations, and that natural selection is strong in this system.