Changes in Retinal Function and Morphology Are Early Clinical Signs of Disease in Cattle with Bovine Spongiform Encephalopathy

Bovine spongiform encephalopathy (BSE) belongs to a group of fatal, transmissible protein misfolding diseases known as transmissible spongiform encephalopathies (TSEs). All TSEs are caused by accumulation of misfolded prion protein (PrP^Sc) throughout the central nervous system (CNS), which results in neuronal loss and ultimately death. Like other protein misfolding diseases including Parkinson’s disease and Alzheimer’s disease, TSEs are generally not diagnosed until the onset of disease after the appearance of unequivocal clinical signs. As such, identification of the earliest clinical signs of disease may facilitate diagnosis. The retina is the most accessible part of the central nervous system, and retinal pathology in TSE affected animals has been previously reported. Here we describe antemortem changes in retinal function and morphology that are detectable in BSE inoculated animals several months (up to 11 months) prior to the appearance of any other signs of clinical disease. We also demonstrate that differences in the severity of these clinical signs reflect the amount of PrP^Sc accumulation in the retina and the resulting inflammatory response of the tissue. These results are the earliest reported clinical signs associated with TSE infection and provide a basis for understanding the pathology and evaluating therapeutic interventions.     

Differential Effects of Tra2? Isoforms on HIV-1 RNA Processing and Expression

Balanced processing of HIV-1 RNA is critical to virus replication and is regulated by host factors. In this report, we demonstrate that overexpression of either Tra2α or Tra2β results in a marked reduction in HIV-1 Gag/ Env expression, an effect associated with changes in HIV-1 RNA accumulation, altered viral splice site usage, and a block to export of HIV-1 genomic RNA. A natural isoform of Tra2β (Tra2ß3), lacking the N-terminal RS domain, also suppressed HIV-1 expression but had different effects on viral RNA processing. The functional differences between the Tra2β isoforms were also observed in the context of another RNA substrate indicating that these factors have distinct functions within the cell. Finally, we demonstrate that Tra2ß depletion results in a selective reduction in HIV-1 Env expression as well as an increase in multiply spliced viral RNA. Together, the findings indicate that Tra2α/β can play important roles in regulating HIV-1 RNA metabolism and expression.     

Analytical Bias in the Measurement of Serum 25-Hydroxyvitamin D Concentrations Impairs Assessment of Vitamin D Status in Clinical and Research Settings

Measured serum 25-hydroxyvitamin D concentrations vary depending on the type of assay used and the specific laboratory undertaking the analysis, impairing the accurate assessment of vitamin D status. We investigated differences in serum 25-hydroxyvitamin D concentrations measured at three laboratories (laboratories A and B using an assay based on liquid chromatography-tandem mass spectrometry and laboratory C using a DiaSorin Liaison assay), against a laboratory using an assay based on liquid chromatography-tandem mass spectrometry that is certified to the standard reference method developed by the National Institute of Standards and Technology and Ghent University (referred to as the ‘certified laboratory’). Separate aliquots from the same original serum sample for a subset of 50 participants from the Ausimmune Study were analysed at the four laboratories. Bland-Altman plots were used to visually check agreement between each laboratory against the certified laboratory. Compared with the certified laboratory, serum 25-hydroxyvitamin D concentrations were on average 12.4 nmol/L higher at laboratory A (95% limits of agreement: -17.8,42.6); 12.8 nmol/L higher at laboratory B (95% limits of agreement: 0.8,24.8); and 10.6 nmol/L lower at laboratory C (95% limits of agreement: -48.4,27.1). The prevalence of vitamin D deficiency (defined here as 25-hydroxyvitamin D <50 nmol/L) was 24%, 16%, 12% and 41% at the certified laboratory, and laboratories A, B, and C, respectively. Our results demonstrate considerable differences in the measurement of 25-hydroxyvitamin D concentrations compared with a certified laboratory, even between laboratories using assays based on liquid chromatography-tandem mass spectrometry, which is often considered the gold-standard assay. To ensure accurate and reliable measurement of serum 25-hydroxyvitamin D concentrations, all laboratories should use an accuracy-based quality assurance system and, ideally, comply with international standardisation efforts.     

Maternal Antioxidant Levels in Pregnancy and Risk of Preeclampsia and Small for Gestational Age Birth: A Systematic Review and Meta-Analysis

Background

Oxidative stress in preeclampsia and small for gestational age (SGA) birth suggests antioxidant supplementation could prevent these conditions. However, it remains unclear whether maternal antioxidant levels are systematically lower in these pregnancies.

Objective

To conduct a systematic review of the association between maternal antioxidant levels during pregnancy and preeclampsia or SGA.

Methods

We searched PubMed, Embase, and several other databases from 1970–2013 for observational studies that measured maternal blood levels of non-enzymatic antioxidants (vitamins A, C, E, and carotenoids) during pregnancy or within 72 hours of delivery. The entire review process was done in duplicate. Study quality was assessed using the Newcastle-Ottawa Scale and additional questions. We pooled the standardized mean difference (SMD) across studies, stratified by outcome and pregnancy trimester, and investigated heterogeneity using meta-regression.

Results

We reviewed 1,882 unique citations and 64 studies were included. Most studies were small with important risk of bias. Among studies that addressed preeclampsia (n = 58) and SGA (n = 9), 16% and 66%, respectively, measured levels prior to diagnosis. The SMDs for vitamins A, C, and E were significantly negative for overall preeclampsia, but not for mild or severe preeclampsia subtypes. Significant heterogeneity was observed in all meta-analyses and most could not be explained. Evidence for lower carotenoid antioxidants in preeclampsia and SGA was limited and inconclusive. Publication bias appears likely.

Conclusions

Small, low-quality studies limit conclusions that can be drawn from the available literature. Observational studies inconsistently show that vitamins C and E or other antioxidants are lower in women who develop preeclampsia or SGA. Reverse causality remains a possible explanation for associations observed. New clinical trials are not warranted in light of this evidence; however, additional rigorous observational studies measuring antioxidant levels before clinical detection of preeclampsia and SGA may clarify whether levels are altered at a causally-relevant time of pregnancy.     

BREEDING SYSTEMS OF CENTRAL AMERICAN APHELANDRA (ACANTHACEAE)

Controlled pollinations, followed by germination studies of seeds resulting from self- and cross-pollination, were carried out using plants from 12 populations of nine species of Aphelandra (Acanthaceae), a genus of neotropical shrubs and herbs. These results are combined with data from field studies of flower morphology, phenology, and pollinator relationships to estimate breeding system of each species. All species have floral morphological traits that prevent autogamy. Plants from five populations of five species experience low levels of geitonogamous pollen transfer; they produce few flowers daily and are pollinated by traplining hummingbirds. Excepting A. storkii, these plants are fully self-compatible (SC), and seeds from selfing are as viable as crossed seeds. Aphelandra storkii is partially self-incompatible (SI) and produces seeds from selfing that tend to germinate less successfully than crossed seeds. Plants from the remaining populations are profusely flowering shrubs, and even those pollinated by traplining hummingbirds should experience higher levels of geitonogamy. Aphelandra deppeana is pollinated by territorial hummingbirds, which should further increase the incidence of geitonogamy. All shrub species are partially SI, and two species (A. leonardii and A. sinclairiana) show significant reduced germination of selfed vs. crossed seeds. The breeding system of these species is thus modified by postpollination factors that favor the formation and maturation of outcrossed seeds. It is suggested that Aphelandra species, like other herbs and shrubs of tropical forest understory, possess a combination of breeding system traits that promote outcrossing but do not exclude geitonogamy.     

New conjugates of antitumor antibiotic doxorubicin with water-soluble galactomannan: synthesis and biological activity

New water-soluble conjugates in the form of Schiff bases (DGM-1 and DGM-2) were prepared by the interaction of water-soluble periodate-oxidized galactomannan with doxorubicin or N-(L-lysyl)doxorubicin, respectively. The water-soluble galactomannan (DAVANAT a commercial product of Pro-Pharmaceuticals company) was obtained by partial acidic hydrolysis of high-molecular-mass galactomannan from Cyamopsis tetragonoloba (guar gum) seeds. The conjugate stability was studied in aqueous solutions. The DGM-1 antiproliferative activity was comparable with that of doxorubicin on three models: cell lines of murine melanoma B 16-F1, human breast cancer MCF-7 (HTB-22), and human colon cancer HT-29 (HTB-38). DGM-2 was poorly active in all the three tests. DGM- 1 can thus be regarded as a high-molecular-mass depot form of doxorubicin.     

An allosteric rheostat in HIV-1 gp120 reduces CCR5 stoichiometry required for membrane fusion and overcomes diverse entry limitations

Binding of the human immunodeficiency virus (HIV-1) envelope glycoprotein gp120 to the CCR5 co-receptor reduces constraints on the metastable transmembrane subunit gp41, thereby enabling gp41 refolding, fusion of viral and cellular membranes, and infection. We previously isolated adapted HIV-1_JRCSF variants that more efficiently use mutant CCR5s, including CCR5(Δ18) lacking the important tyrosine sulfate-containing amino terminus. Effects of mutant CCR5 concentrations on HIV-1 infectivities were highly cooperative, implying that several may be required. However, because wild-type CCR5 efficiently mediates infections at trace concentrations that were difficult to measure accurately, analyses of its cooperativity were not feasible. New HIV-1_JRCSF variants efficiently use CCR5(HHMH), a chimera containing murine extracellular loop 2. The adapted virus induces large syncytia in cells containing either wild-type or mutant CCR5s and has multiple gp120 mutations that occurred independently in CCR5(Δ18)-adapted virus. Accordingly, these variants interchangeably use CCR5(HHMH) or CCR5(Δ18). Additional analyses strongly support a novel energetic model for allosteric proteins, implying that the adaptive mutations reduce quaternary constraints holding gp41, thus lowering the activation energy barrier for membrane fusion without affecting bonds to specific CCR5 sites. In accordance with this mechanism, highly adapted HIV-1s require only one associated CCR5(HHMH), whereas poorly adapted viruses require several. However, because they are allosteric ensembles, complexes with additional co-receptors fuse more rapidly and efficiently than minimal ones. Similarly, wild-type HIV-1_JRCSF is highly adapted to wild-type CCR5 and minimally requires one. The adaptive mutations cause resistances to diverse entry inhibitors and cluster appropriately in the gp120 trimer interface overlying gp41. We conclude that membrane fusion complexes are allosteric machines with an ensemble of compositions, and that HIV-1 adapts to entry limitations by gp120 mutations that reduce its allosteric hold on gp41. These results provide an important foundation for understanding the mechanisms that control membrane fusion and HIV-1's facile adaptability.