Cryptosporidium parvum infection requires host cell actin polymerization

The intracellular protozoan parasite Cryptosporidium parvum accumulates host cell actin at the interface between the parasite and the host cell cytoplasm. Here we show that the actin polymerizing proteins Arp2/3, vasodilator-stimulated phosphoprotein (VASP), and neural Wiskott Aldrich syndrome protein (N-WASP) are present at this interface and that host cell actin polymerization is necessary for parasite infection.     

Rapid diagnosis of typhoid fever through identification of Salmonella typhi within 18 hours of specimen acquisition by culture of the mononuclear cell-platelet fraction of blood.

Detection of Salmonella typhi in blood by culture of the mononuclear cell-platelet layer was compared with other methods currently used for the diagnosis of typhoid fever. Colonies of S. typhi were present in all mononuclear cell-platelet layer-positive cultures within 18 h of plating and were identified within an additional 10 min by a coagglutination technique. In contrast, identification of all positive cultures by conventional blood culture required 3 days.     

Heterogeneity in spinal radial glia demonstrated by intermediate filament expression and HRP labelling

Summary Considerable evidence indicates that radial glial cells play an active role in guiding growing neurites during development of the vertebrate CNS. In this paper we describe subpopulations of radial glia in the spinal cord of the axolotl. Amphibians maintain radial glia throughout life, and subpopulations are described using anatomical criteria following filling of individual cells with horseradish peroxidase and immunocytochemical staining with a range of intermediate filament antibodies.Radial glial cells in specific regions of the spinal cord stain with a range of antibodies specific to human keratins 8 and 18, and to glial fibrillary acid protein (GFAP). Some of these antibodies show selective staining localized to specific regions of individual glial cell processes. Immunoblotting analysis indicates that two keratins are present in the axolotl CNS corresponding to the two earliest embryonic keratins of vertebrates, keratins 8 and 18. Comparisons of molecular weight indicate that these may correspond to keratins identified inXenopus laevis, the genes of which have been cloned. Axolotl GFAP is also identified in Western blots and may be present in two forms of differing molecular weight.These results are discussed in terms of the likely role of radial glial cells, and comparisons are drawn between the keratin and GFAP types seen, in the axolotl spinal cord and of those in other vertebrate groups.     

The effects of complement activation by cobra venom factor on the migration of T and B lymphocytes into rat thoracic duct lymph.

Experiments were done to see whether C3 or C3-split products are involved in lymphocyte recirculation, with particular reference to B lymphocytes which have C3b receptors. Rats were injected with cobra venom factor (CVF), and the output of subclasses of lymphocytes was measured in thoracic duct lymph in hourly collections during the subsequent 24 h. During the period of acute C3 activation which lasted for 2-8 h, the output of lymphocytes decreased by 47%, but returned to normal at later times, when C3 levels were reduced to less than 20% normal. There was no effect on the output of C3b receptor lymphocytes, and this receptor was not blocked probably because initial C3 levels in lymph were only 13% of blood levels, so that only small amounts of C3b were generated in lymph. When these lymphocytes were labelled and injected i.v. they migrated with the slow rate which is characteristic of normal B lymphocytes. The main effect of CVF was to reduce the output of T lymphocytes by 58% during the phase of acute C3 activation. When normal thoracic duct lymphocytes were labelled and injected, their rate of reappearance in thoracic duct lymph was only reduced during this phase. It was concluded that recirculation of lymphocytes is not C3 dependent, and that insufficient C3b is generated in lymphoid tissues to block C3b receptors on B lymphocytes during periods of rapid C3 activation. However the migratory rate of T lymphocytes through these tissues is reduced during this period, and it is suggested that this may be due to an effect of C3 split products on macrophages which lie along T-lymphocyte traffic routes.     

Efficacy of oocytes donated by older women in an oocyte donation programme

Population and insemination studies indicate that women experiencedeclining fertility with ageing. The question therefore ariseswhether older women are suitable oocyte donors. This study addressesthis issue by examining the relationship between oocyte donorage and clinical outcome in a large oocyte donation programme.We retrospectively reviewed data from 458 consecutive oocytedonation cycles completed by 164 different designated oocytedonors. Data were divided into two groups: group A, cycles withdonors aged 21–30 years at the time of follicular aspiration(193 cycles, 88 donors); and group B, cycles with donors aged31–40 years at the time of follicular aspiration (265cycles, 86 donors). Five donors, because of ageing during repetitivedonations, contributed data to groups A and B. In a given cycle,all oocytes for a recipient came from only one designated donor.Comparing the two donor groups, there was no difference in theamount of gonadotrophin used to achieve optimal stimulation;however, more oocytes were obtained from group A than groupB donors (16.8 ± 6.9 and 15.1 ± 8.1 respectively,P < 0.05). Similar percentages of oocytes were fertilizedin each group, resulting in the transfer of comparable numbersof embryos (4.5 ± 1.1 and 4.4 ± 13 respectively).Comparable clinical pregnancy rates were achieved (group A,36%; group B, 37%). The spontaneous abortion rates were alsosimilar (group A, 20%; group B, 12%), resulting in comparableongoing and delivered pregnancy rates per cycle (group A, 29%;group B, 32%) and per embryo transferred (group A, 6.4%; groupB, 7.3%). In conclusion, women of proven fertility should notbe excluded from donating oocytes simply because of their age.There exists a cohort of fertile women who resist the decreasingfecundity and increasing spontaneous abortion rates associatedwith ageing. With careful screening, many women of proven fertilitycan donate oocytes until the age of 40 years with an efficacyequal to that of younger women. Given the relative shortageof suitable oocyte donors, and increasing requests from recipientswith previous donor oocyte babies to obtain oocytes from thesame, now older, donor, the findings of this study are of practicalclinical importance.     

Synergy between the genes for butyrylcholinesterase K variant and apolipoprotein E4 in late-onset confirmed Alzheimer's disease

The allelic frequency of the gene for the K variant of butyrylcholinesterase (BCHE-K) was 0.17 in 74 subjects with late-onset (age > 65 years) histopathologically diagnosed Alzheimer's disease (AD), which was higher than the frequencies in 104 elderly control subjects (0.09), in 14 early-onset cases of confirmed AD (0.07) and in 29 confirmed cases of other dementia (0.10). The association of BCHE-K with late-onset AD was limited to carriers of the epsilon 4 allele of the apolipoprotein E gene (APOE), among whom the presence of BCHE-K gave an odds ratio of confirmed late-onset AD of 6.9 (95% C.I. 1.65-29) in subjects > 65 years and of 12.8 (1.9-86) in subjects > 75 years. In APOE epsilon 4 carriers over 75 years, only 1/22 controls, compared with 10/24 confirmed late-onset AD cases, had BCHE-K. We suggest that BCHE-K, or a nearby gene on chromosome 3, acts in synergy with APOE epsilon 4 as a susceptibility gene for late-onset AD.      

Differential roles of CCL2 and CCR2 in host defense to coronavirus infection

The CC chemokine ligand 2 (CCL2, monocyte chemoattractant protein-1) is important in coordinating the immune response following microbial infection by regulating T cell polarization as well as leukocyte migration and accumulation within infected tissues. The present study examines the consequences of mouse hepatitis virus (MHV) infection in mice lacking CCL2 (CCL2(-/-)) in order to determine if signaling by this chemokine is relevant in host defense. Intracerebral infection of CCL2(-/-) mice with MHV did not result in increased morbidity or mortality as compared to either wild type or CCR2(-/-) mice and CCL2(-/-) mice cleared replicating virus from the brain. In contrast, CCR2(-/-) mice displayed an impaired ability to clear virus from the brain that was accompanied by a reduction in the numbers of antigen-specific T cells as compared to both CCL2(-/-) and wild-type mice. The paucity in T cell accumulation within the central nervous system (CNS) of MHV-infected CCR2(-/-) mice was not the result of either a deficiency in antigen-presenting cell (APC) accumulation within draining cervical lymph nodes (CLN) or the generation of virus-specific T cells within this compartment. A similar reduction in macrophage infiltration into the CNS was observed in both CCL2(-/-) and CCR2(-/-) mice when compared to wild-type mice, indicating that both CCL2 and CC chemokine receptor 2 (CCR2) contribute to macrophage migration and accumulation within the CNS following MHV infection. Together, these data demonstrate that CCR2, but not CCL2, is important in host defense following viral infection of the CNS, and CCR2 ligand(s), other than CCL2, participates in generating a protective response.