Killing of Friend erythroleukaemia cells by cytochalasin B is cell cycle specific

Exposure to 2.0 micrograms/ml cytochalasin B causes loss of viability in Friend erythroleukaemia cells. This effect is only observed however in cells undergoing mitosis.     

Morphological observations on the unique paired capillaries of the opossum retina

Light-microscopic and ultrastructural analysis of the ocular tissues of the North American opossum (Didelphis virginiana) revealed that the arterial and venous segments of retinal vessels, including capillaries of the smallest calibre, occur in pairs. They do not form anastomotic networks, the common pattern in mammals with vascularised retinae, but instead the two segments of the pair join to form hairpin end loops. The pairedd vessels, with the arteriolar limb usually on the vitread aspect, penetrate the retina and branch to form three distinct layers of capillaries. The most superficial lies in the nerve fiber layer, the middle is situated in the inner nuclear layer and the deepest extends to the external limiting membrane, which is considerably deeper than in normal mammalian holangiotic retinae. The paired capillaries display classical morphological features of central nervous system capillaries, i.e., they are lined by continuous endothelial cells united by tight junctions. The lining endothelium is supported by a distinct basal lamina that splits to envelop pericytes. The latter, although abundant, are invariably interposed between the two vessels that form each vascular unit. Phylogenetic and functional aspects of this unique form of retinal vascularisation are discussed.     

The Effects of CX3CR1 Deficiency and Irradiation on the Homing of Monocyte-Derived Cell Populations in the Mouse Eye

This study examined whether CX₃CR1 deficiency altered monocytic cell replenishment dynamics in ocular tissues in the context of radiation chimeras. Long-term effects of irradiation and effects of sublethal irradiation on ocular macrophages were also assessed. Bone marrow from BALB/c Cx ₃ cr1 ^+/gfp or Cx ₃ cr1 ^gfp/gfp mice was used to reconstitute full body irradiated WT mice and donor cell densities in the uveal tract were compared at 4 and 8 weeks post-transplantation. BALB/c and C57BL/6J chimeric mice were examined at 6 months of age to determine strain-related differences in microglial replenishment and radiation sensitivity. A separate cohort of mice were sublethally irradiated (5.5 Gy) and retinal tissue assessed 8 and 12 weeks later. CX₃CR1 deficiency altered the early replenishment of monocytes in the posterior iris but not in the iris stroma, choroid or retina. In six month old chimeric mice, there were significantly higher GFP⁺ cell densities in the uveal tract when compared to non-irradiated 8-12 week old Cx ₃ cr1 ^+/gfp mice. Additionally, MHC Class II expression was upregulated on hyalocytes and GFP⁺ cells in the peripheral retina and the repopulation of microglia appeared to be more rapid in C57BL/6J mice compared to BALB/c mice. Transient expression of MHC Class II was observed on retinal vasculature in sublethally irradiated mice. These data indicate CX₃CR1-deficiency only slightly alters monocyte-derived cell replenishment in the murine uveal tract. Lethal irradiation leads to long-term increase in monocytic cell density in the uveal tract and retinal microglial activation, possibly as a sequelae to local irradiation induced injury. Microglial replenishment in this model appears to be strain dependent.     

Thyroid hormone modulation during zebrafish development recapitulates evolved diversity in danionin jaw protrusion mechanics

Protrusile jaws are a highly useful innovation that has been linked to extensive diversification in fish feeding ecology. Jaw protrusion can enhance the performance of multiple functions, such as suction production and capturing elusive prey. Identifying the developmental factors that alter protrusion ability will improve our understanding of fish diversification. In the zebrafish protrusion arises postmetamorphosis. Fish metamorphosis typically includes significant changes in trophic morphology, accompanies a shift in feeding niche and coincides with increased thyroid hormone production. We tested whether thyroid hormone affects the development of zebrafish feeding mechanics. We found that it affected all developmental stages examined, but that effects were most pronounced after metamorphosis. Thyroid hormone levels affected the development of jaw morphology, feeding mechanics, shape variation, and cranial ossification. Adult zebrafish utilize protrusile jaws, but an absence of thyroid hormone impaired development of the premaxillary bone, which is critical to jaw protrusion. Premaxillae from early juvenile zebrafish and hypothyroid adult zebrafish resemble those from adults in the genera Danionella, Devario, and Microdevario that show little to no jaw protrusion. Our findings suggest that evolutionary changes in how the developing skulls of danionin minnows respond to thyroid hormone may have promoted diversification into different feeding niches.     

Simultaneous analysis of multiple aminothiols in human plasma by high performance liquid chromatography with fluorescence detection

Aminothiols serve numerous vital functions in biochemistry, including detoxification and regulation of cellular metabolism, enzymatic activity, and protein trafficking and degradation. Plasma aminothiol concentrations are frequently measured for clinical and translational research investigating oxidative stress, and for routine clinical diagnosis and monitoring of vascular injury. Although a variety of techniques are available to measure aminothiol concentrations in plasma, high performance liquid chromatography with fluorescence detection (HPLC–FD) is the most widely used. This review summarizes HPLC–FD methods, including pre-analytical considerations, procedures for sample reduction, derivatization, and chromatographic separation of the primary biological aminothiols cysteine, homocysteine, cysteinylglycine, and glutathione in human plasma.     

Sero-prevalence and incidence of A/H1N1 2009 influenza infection in Scotland in winter 2009-2010

Background

Sero-prevalence is a valuable indicator of prevalence and incidence of A/H1N1 2009 infection. However, raw sero-prevalence data must be corrected for background levels of cross-reactivity (i.e. imperfect test specificity) and the effects of immunisation programmes.

Methods and Findings

We obtained serum samples from a representative sample of 1563 adults resident in Scotland between late October 2009 and April 2010. Based on a microneutralisation assay, we estimate that 44% (95% confidence intervals (CIs): 40–47%) of the adult population of Scotland were sero-positive for A/H1N1 2009 influenza by 1 March 2010. Correcting for background cross-reactivity and for recorded vaccination rates by time and age group, we estimated that 34% (27–42%) were naturally infected with A/H1N1 2009 by 1 March 2010. The central estimate increases to >40% if we allow for imperfect test sensitivity. Over half of these infections are estimated to have occurred during the study period and the incidence of infection in late October 2009 was estimated at 4.3 new infections per 1000 people per day (1.2 to 7.2), falling close to zero by April 2010. The central estimate increases to over 5.0 per 1000 if we allow for imperfect test specificity. The rate of infection was higher for younger adults than older adults. Raw sero-prevalences were significantly higher in more deprived areas (likelihood ratio trend statistic = 4.92,1 df, P = 0.03) but there was no evidence of any difference in vaccination rates.

Conclusions

We estimate that almost half the adult population of Scotland were sero-positive for A/H1N1 2009 influenza by early 2010 and that the majority of these individuals (except in the oldest age classes) sero-converted as a result of natural infection with A/H1N1 2009. Public health planning should consider the possibility of higher rates of infection with A/H1N1 2009 influenza in more deprived areas.