Virus-Specific Deoxyribonucleic Acid in Simian Virus 40-Exposed Hamster Cells: Correlation with S and T Antigens

Several homologous hamster embryonic cell lines, transformed in association with simian virus (SV) 40 infection, were examined for the presence of deoxyribonucleic acid (DNA) complementary to SV40 ribonucleic acid (RNA) made in vitro. The methods employed permitted the detection of 10(-5) mug of viral DNA in 100 mug of cellular DNA, corresponding to one-fifth of an SV40 DNA molecule per cell. Those lines which contained both the SV40 surface (S) and tumor (T) antigens also contained DNA complementary to SV40 RNA synthesized in vitro. In contrast, neither of two lines which contained S, but not T, antigen contained detectable DNA complementary to SV40 RNA. These findings suggest that the production of S antigen does not depend upon the persistence of SV40 DNA in transformed cells.     

Using a Human Challenge Model of Infection to Measure Vaccine Efficacy: A Randomised,Controlled Trial Comparing the Typhoid Vaccines M01ZH09 with Placebo and Ty21a

BackgroundTyphoid persists as a major cause of global morbidity. While several licensed vaccines to prevent typhoid are available, they are of only moderate efficacy and unsuitable for use in children less than two years of age. Development of new efficacious vaccines is complicated by the human host-restriction of Salmonella enterica serovar Typhi (S. Typhi) and lack of clear correlates of protection. In this study, we aimed to evaluate the protective efficacy of a single dose of the oral vaccine candidate, M01ZH09, in susceptible volunteers by direct typhoid challenge.ConclusionsDespite successfully demonstrating the use of a human challenge study to directly evaluate vaccine efficacy, a single-dose M01ZH09 failed to demonstrate significant protection after challenge with virulent Salmonella Typhi in this model. Anti-Vi antibody detected prior to vaccination played a major role in outcome after challenge.

Trial registration

ClinicalTrials.gov ({"type":"clinical-trial","attrs":{"text":"NCT01405521","term_id":"NCT01405521"}}NCT01405521) and EudraCT (number 2011-000381-35).     

Endogenous UVA-photosensitizers: mediators of skin photodamage and novel targets for skin photoprotection.

Endogenous chromophores in human skin serve as photosensitizers involved in skin photocarcinogenesis and photoaging. Absorption of solar photons, particularly in the UVA region, induces the formation of photoexcited states of skin photosensitizers with subsequent generation of reactive oxygen species (ROS), organic free radicals and other toxic photoproducts that mediate skin photooxidative stress. The complexity of endogenous skin photosensitizers with regard to molecular structure, pathways of formation, mechanisms of action, and the diversity of relevant skin targets has hampered progress in this area of photobiology and most likely contributed to an underestimation of the importance of endogenous sensitizers in skin photodamage. Recently, UVA-fluorophores in extracellular matrix proteins formed posttranslationally as a consequence of enzymatic maturation or spontaneous chemical damage during chronological and actinic aging have been identified as an abundant source of light-driven ROS formation in skin upstream of photooxidative cellular stress. Importantly, sensitized skin cell photodamage by this bystander mechanism occurs after photoexcitation of sensitizers contained in skin structural proteins without direct cellular photon absorption thereby enhancing the potency and range of phototoxic UVA action in deeper layers of skin. The causative role of photoexcited states in skin photodamage suggests that direct molecular antagonism of photosensitization reactions using physical quenchers of photoexcited states offers a novel chemopreventive opportunity for skin photoprotection.     

Cycloamylose-accelerated cleavage of acylimidazoles

Hydrolyses of N-trans-cinnamoylimidazole (1) and N-acetylimidazole (2) were accelerated by cyclohexaamylose (α-CA) and cycloheptaamylose (β-CA) at 25°C. The cleavage of the amide bond in 1 at pH 9.0 was accelerated by α-CA and β-CA by 28- and 38-fold, respectively, whereas the cleavage of the amide bond in 2 at pH 7.0 was accelerated by α-CA and β-CA by 50- and 28-fold, respectively. The β-CA-accelerated hydrolysis of 1 proceeded via binding, acylation of β-CA, and deacylation of β-CA trans-cinnamate, which is consistent with the pathway used by serine proteases. The deuterium oxide solvent isotope effects for acylation and deacylation steps indicate nucleophilic attack in acylation and general basic attack in deacylation. The present finding of the acceleration by cycloamyloses in the cleavages of amide bonds in 1 and 2 indicates that cycloamyloses are an excellent model for hydrolytic enzymes.     

Annual variation in maternal age and calving date generate cohort effects in moose (<Emphasis Type="Italic">Alces alces</Emphasis>) body mass

A general feature of the demography of large ungulates is that many demographic traits are dependent on female body mass at early ages. Thus, identifying the factors affecting body mass variation can give important mechanistic understanding of demographic processes. Here we relate individual variation in autumn and winter body mass of moose calves living at low density on an island in northern Norway to characteristics of their mother, and examine how these relationships are affected by annual variation in population density and climate. Body mass increased with increasing age of their mother, was lower for calves born late in the spring, decreased with litter size and was larger for males than for female calves. No residual effects of variation in density and climate were present after controlling for annual variation in mother age and calving date. The annual variation in adult female age structure and calving date explained a large part (71–75%) of the temporal variation in calf body mass. These results support the hypotheses that (a) body mass of moose calves are affected by qualities associated with mother age (e.g. body condition, calving date); and (b) populations living at low densities are partly buffered against temporal fluctuations in the environment.     

Identifying and correcting spatial bias in opportunistic citizen science data for wild ungulates in Norway

Many publications make use of opportunistic data, such as citizen science observation data, to infer large‐scale properties of species’ distributions. However, the few publications that use opportunistic citizen science data to study animal ecology at a habitat level do so without accounting for spatial biases in opportunistic records or using methods that are difficult to generalize. In this study, we explore the biases that exist in opportunistic observations and suggest an approach to correct for them. We first examined the extent of the biases in opportunistic citizen science observations of three wild ungulate species in Norway by comparing them to data from GPS telemetry. We then quantified the extent of the biases by specifying a model of the biases. From the bias model, we sampled available locations within the species’ home range. Along with opportunistic observations, we used the corrected availability locations to estimate a resource selection function (RSF). We tested this method with simulations and empirical datasets for the three species. We compared the results of our correction method to RSFs obtained using opportunistic observations without correction and to RSFs using GPS‐telemetry data. Finally, we compared habitat suitability maps obtained using each of these models. Opportunistic observations are more affected by human access and visibility than locations derived from GPS telemetry. This has consequences for drawing inferences about species’ ecology. Models naïvely using opportunistic observations in habitat‐use studies can result in spurious inferences. However, sampling availability locations based on the spatial biases in opportunistic data improves the estimation of the species’ RSFs and predicted habitat suitability maps in some cases. This study highlights the challenges and opportunities of using opportunistic observations in habitat‐use studies. While our method is not foolproof it is a first step toward unlocking the potential of opportunistic citizen science data for habitat‐use studies.     

Secondary and Apparent Primary Antibody Responses After Group A Streptococcal Vaccination of 21 Children

A partially purified M protein, extracted from a mouse-virulent strain of type 3, group A streptococcus, was administered subcutaneously in gradually increasing amounts at weekly intervals to 21 children in a Family Program. Seven children with type 3 bactericidal antibody in prevaccination sera showed a secondary response. Of 14 children with no detectable type 3 bactericidal antibody prior to vaccination, 13 developed definite type 3 antibody during or soon after vaccination. This response appeared to be of the primary variety in at least some of the 13 children because (i) the total incidence of antibody response (20 of 21) was greater than can be accounted for by the documented incidence of clinical and subclinical type 3 infections among children of our Family Program during a period of 14 years, (ii) the response in the 13 children with no detectable antibody prior to vaccination was more delayed than in those showing a definite secondary response, and (iii) on the average, the amount of vaccine needed for a response in these 13 children was 15 to 28 times greater than that required for the secondary response. Local skin reactions were variable among the vaccinated children. Systemic reactions were infrequent and not severe. The giving of multiple injections of partially purified M protein did not seem to cause cutaneous hypersensitivity.     

Using multiple biomarkers and determinants to obtain a better measurement of oxidative stress: a latent variable structural equation model approach

Purpose: Since oxidative stress involves a variety of cellular changes, no single biomarker can serve as a complete measure of this complex biological process. The analytic technique of structural equation modeling (SEM) provides a possible solution to this problem by modelling a latent (unobserved) variable constructed from the covariance of multiple biomarkers.

Methods: Using three pooled datasets, we modelled a latent oxidative stress variable from five biomarkers related to oxidative stress: F₂-isoprostanes (FIP), fluorescent oxidation products, mitochondrial DNA copy number, γ-tocopherol (Gtoc) and C-reactive protein (CRP, an inflammation marker closely linked to oxidative stress). We validated the latent variable by assessing its relation to pro- and anti-oxidant exposures.

Results: FIP, Gtoc and CRP characterized the latent oxidative stress variable. Obesity, smoking, aspirin use and β-carotene were statistically significantly associated with oxidative stress in the theorized directions; the same exposures were weakly and inconsistently associated with the individual biomarkers.

Conclusions: Our results suggest that using SEM with latent variables decreases the biomarker-specific variability, and may produce a better measure of oxidative stress than do single variables. This methodology can be applied to similar areas of research in which a single biomarker is not sufficient to fully describe a complex biological phenomenon.     

In vitro effects of a C4'-oxidized abasic site on DNA polymerases

Oxidative damage to DNA produces abasic sites resulting from the formal hydrolysis of the nucleotides' glycosidic bonds, along with a variety of oxidized abasic sites. The C4'-oxidized abasic site (C4-AP) is produced by several DNA-damaging agents. This lesion accounts for approximately 40% of the DNA damage produced by bleomycin. The effect of a C4'-oxidized abasic site incorporated at a defined site in a template was examined on Klenow fragments with and without 3' --> 5' exonuclease activity. Both enzymes preferentially incorporated dA > dG > dC, T opposite C4-AP. Neither enzyme is able to extend the primer past the lesion. Experiments with regular AP sites in an otherwise identical template indicate that Klenow does not differentiate between these two disparate abasic sites. Extension of the primer by alternative polymerases pol II, pol II exo(-), pol IV, and pol V was examined. Pol II exo(-) was most efficient. Qualitative translesion synthesis experiments showed that pol II exo(-) preferentially incorporates T opposite C4-AP, followed in order by dG, dA, and dC. Thymidine incorporation opposite C4'-AP is distinct from the pol II exonuclease interaction with a regular AP site in an otherwise identical template. These in vitro experiments suggest that bypass polymerases may play a crucial role in survival of cells in which C4-AP is produced, and unlike a typical AP site, the C4-AP lesion may not follow the "A-rule". The interaction between bypass polymerases and a C4-AP lesion could explain the high levels of G:C --> T:A transversions in cells treated with bleomycin.     

Activation of Salmonella Typhi-Specific Regulatory T Cells in Typhoid Disease in a Wild-Type S. Typhi Challenge Model

Salmonella Typhi (S. Typhi), the causative agent of typhoid fever, causes significant morbidity and mortality worldwide. Currently available vaccines are moderately efficacious, and identification of immunological responses associated with protection or disease will facilitate the development of improved vaccines. We investigated S. Typhi-specific modulation of activation and homing potential of circulating regulatory T cells (T_reg) by flow and mass cytometry using specimens obtained from a human challenge study. Peripheral blood mononuclear cells were obtained from volunteers pre- and at multiple time-points post-challenge with wild-type S. Typhi. We identified differing patterns of S. Typhi-specific modulation of the homing potential of circulating T_reg between volunteers diagnosed with typhoid (TD) and those who were not (No TD). TD volunteers demonstrated up-regulation of the gut homing molecule integrin α4ß7 pre-challenge, followed by a significant down-regulation post-challenge consistent with T_reg homing to the gut. Additionally, S. Typhi-specific T_reg from TD volunteers exhibited up-regulation of activation molecules post-challenge (e.g., HLA-DR, LFA-1). We further demonstrate that depletion of T_reg results in increased S. Typhi-specific cytokine production by CD8+ T_EM in vitro. These results suggest that the tissue distribution of activated T_reg, their characteristics and activation status may play a pivotal role in typhoid fever, possibly through suppression of S. Typhi-specific effector T cell responses. These studies provide important novel insights into the regulation of immune responses that are likely to be critical in protection against typhoid and other enteric infectious diseases.