Age-related changes in smooth pursuit initiation

Quantitative analysis of eye movements is a useful tool for examining the behavioural effects of ageing. Although the effect of ageing on saccadic eye movement has been examined in some detail, the effect of ageing on a second class of eye movement, smooth pursuit (SP), has received less attention. We examined the initiation of SP in a group of fifteen healthy older people (mean age 72 years) and compared their performance with that of ten young controls (mean age 21 years). Although their performance was qualitatively similar, pursuit latency was increased in the older group. Investigation of the gap effect on pursuit revealed that, while the gap effect was present in the older group, it seemed to be directionally asymmetrical. When the longer absolute latencies were taken into account, although the gap effect in the two groups was identical for leftward tasks, for rightward tasks it was reduced in the older group, although this did not reach statistical significance. The difference between the old and young groups was driven by some of the older subjects. At the longest gap duration employed (400 ms), while there was a clear gap effect for leftward tasks in these subjects, there was no reduction in latency, or increases in latency, for rightward tasks. This asymmetry was not related to chronological age within the older group. These results suggest an age-related alteration in SP initiation that is more complex than general slowing of information processing in ageing. They may be indicative of additional ageing effects specific to the oculomotor or closely related systems.     

Interstrain variability of larval photokinesis inDrosophila melanogaster

Larvae from seven laboratory strains and eight isofemale lines ofDrosophila melanogaster differ significantly with regard to their responses to light in a photokinesis assay in which the larvae are tested en masse. Larvae from the CA-2 laboratorystock fail to disperse on assay plates, although observations of individual CA-2 larvae suggest that the larvae are repelled by light. Larvae from all of the other laboratory stocks and all of the isofemale lines (except LI2 and NC5) avoid light in the photokinesis assay. Larvae from some stocks are much more strongly repelled by light than larvae from other stocks. LI2 larvae are unresponsive to light in most replicates of the photokinesis assay, while NC5 larvae are consistently unresponsive to light. Observations of F₁ heterozygotes suggest that the allele(s) that affects the vision of LI2 and NC5 larvae has net effects on the animals' behavior that are partially dominant and recessive, respectively.     

Monkeypox virus detection in rodents using real-time 3'-minor groove binder TaqMan assays on the Roche LightCycler

During the summer of 2003, an outbreak of human monkeypox occurred in the Midwest region of the United States. In all, 52 rodents suspected of being infected with monkeypox virus were collected from an exotic pet dealer and from private homes. The rodents were euthanized and submitted for testing to the United States Army Medical Research Institute of Infectious Diseases by the Galesburg Animal Disease Laboratory, Illinois Department of Agriculture. The rodent tissue samples were appropriately processed and then tested by using an integrated approach involving real-time polymerase chain reaction (PCR) assays, an antigen-detection immunoassay, and virus culture. We designed and extensively tested two specific real-time PCR assays for rapidly detecting monkeypox virus DNA using the Vaccinia virus F3L and N3R genes as targets. The assays were validated against panels of orthopox viral and miscellaneous bacterial DNAs. A pan-orthopox electrochemiluminescence (ECL) assay was used to further confirm the presence of Orthopoxvirus infection of the rodents. Seven of 12 (58%) animals (seven of 52 (15%) of all animals) tested positive in both monkeypox-specific PCR assays and two additional pan-orthopox PCR assays (in at least one tissue). The ECL results showed varying degrees of agreement with PCR. One hamster and three gerbils were positive by both PCR and ECL for all tissues tested. In addition, we attempted to verify the presence of monkeypox virus by culture on multiple cell lines, by immunohistology, and by electron microscopy, with negative results. Sequencing the PCR products from the samples indicated 100% identity with monkeypox virus strain Zaire-96-I-16 (a human isolate from the Congo). These real-time PCR and ECL assays represent a significant addition to the battery of tests for the detection of various orthopoxviruses. In light of the recent monkeypox virus transmissions, early detection of the virus is crucial for both natural outbreaks and potential acts of bioterrorism.     

Human TLR-7-, -8-, and -9-mediated induction of IFN-alpha/beta and -lambda Is IRAK-4 dependent and redundant for protective immunity to viruses

Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.