Effects of medroxyprogesterone acetate on gestation in mink

Mink ovariectomized 14 days after the first of two matings received injections of 2 mg MPA, the same MPA treatment + an oestradiol-17 beta implant or no replacement therapy. Some mink were ovariectomized after implantation and given a single dose of 2 mg MPA or no replacement therapy. MPA persisted in the serum at detectable levels for 13 or more days in all mink treated. MPA and MPA + oestradiol induced uterine growth but neither treatment was capable of inducing embryo implantation. More embryos were retained in mink treated with MPA alone and these appeared to be viable. Implanted embryos persisted for a longer period in animals that were ovariectomized and treated with MPA. MPA neither supported pregnancy nor permitted parturition. Serum LH was elevated by 1 week after ovariectomy and elevations persisted for a further 20 or more days. While MPA alone had no apparent negative feedback effects on LH, animals that received MPA + oestradiol did not display any elevation of LH, suggesting that oestradiol or a combination of MPA and oestradiol has a potent negative feedback in mink.     

On the Origins and Control of Community Types in the Human Microbiome

Microbiome-based stratification of healthy individuals into compositional categories, referred to as “enterotypes” or “community types”, holds promise for drastically improving personalized medicine. Despite this potential, the existence of community types and the degree of their distinctness have been highly debated. Here we adopted a dynamic systems approach and found that heterogeneity in the interspecific interactions or the presence of strongly interacting species is sufficient to explain community types, independent of the topology of the underlying ecological network. By controlling the presence or absence of these strongly interacting species we can steer the microbial ecosystem to any desired community type. This open-loop control strategy still holds even when the community types are not distinct but appear as dense regions within a continuous gradient. This finding can be used to develop viable therapeutic strategies for shifting the microbial composition to a healthy configuration.     

Assessment of Transmission in Trachoma Programs over Time Suggests No Short-Term Loss of Immunity

Trachoma programs have dramatically reduced the prevalence of the ocular chlamydia that cause the disease. Some have hypothesized that immunity to the infection may be reduced because of program success in reducing the incidence of infection, and transmission may then increase. Longitudinal studies of multiple communities would be necessary to test this hypothesis. Here, we quantify transmission using an estimated basic reproduction number based on 32 communities during the first, second, and third years of an antibiotic treatment program. We found that there is little to no increase in the basic reproduction number over time. The estimated linear trend in the basic reproduction number, , was found to be −0.025 per year, 95% CI −0.167 to 0.117 per year. We are unable to find evidence supporting any loss of immunity over the course of a 3-year program. This is encouraging, as it allows the possibility that repeated mass antibiotic distributions may eliminate infection from even the most severely affected areas.     

Comparative properties of human alpha-1-proteinase inhibitor glycosylation variants

Variant forms of human alpha-1-proteinase inhibitor (alpha-1-PI), obtained by the treatment of human Hep G2 cells with specific inhibitors of glycosylation were tested for both inhibitory activity and heat stability. All were found to have the same second-order association rate with human neutrophil elastase, indicating a lack of importance of the carbohydrate moiety. In contrast, incompletely glycosylated forms of alpha-1-PI were found to be heat sensitive relative to the mature protein, suggesting a role for carbohydrate in protein stabilization.     

Pyruvate Protects Pathogenic Spirochetes from H2O2 Killing

Pathogenic spirochetes cause clinically relevant diseases in humans and animals, such as Lyme disease and leptospirosis. The causative agent of Lyme disease, Borrelia burgdorferi, and the causative agent of leptospirosis, Leptospria interrogans, encounter reactive oxygen species (ROS) during their enzootic cycles. This report demonstrated that physiologically relevant concentrations of pyruvate, a potent H₂O₂ scavenger, and provided passive protection to B. burgdorferi and L. interrogans against H₂O₂. When extracellular pyruvate was absent, both spirochetes were sensitive to a low dose of H₂O₂ (≈0.6 µM per h) generated by glucose oxidase (GOX). Despite encoding a functional catalase, L. interrogans was more sensitive than B. burgdorferi to H₂O₂ generated by GOX, which may be due to the inherent resistance of B. burgdorferi because of the virtual absence of intracellular iron. In B. burgdorferi, the nucleotide excision repair (NER) and the DNA mismatch repair (MMR) pathways were important for survival during H₂O₂ challenge since deletion of the uvrB or the mutS genes enhanced its sensitivity to H₂O₂ killing; however, the presence of pyruvate fully protected ΔuvrB and ΔmutS from H₂O₂ killing further demonstrating the importance of pyruvate in protection. These findings demonstrated that pyruvate, in addition to its classical role in central carbon metabolism, serves as an important H₂O₂ scavenger for pathogenic spirochetes. Furthermore, pyruvate reduced ROS generated by human neutrophils in response to the Toll-like receptor 2 (TLR2) agonist zymosan. In addition, pyruvate reduced neutrophil-derived ROS in response to B. burgdorferi, which also activates host expression through TLR2 signaling. Thus, pathogenic spirochetes may exploit the metabolite pyruvate, present in blood and tissues, to survive H₂O₂ generated by the host antibacterial response generated during infection.     

The upper thermal tolerance for a Texas population of the hairy maggot blow fly Chrysomya rufifacies Macquart (Diptera: Calliphoridae)

1. The hairy maggot blow fly (Chrysomya rufifacies: Macquart) is an invasive necrophagous fly found throughout the continental United States. Chrysomya rufifacies is of medical/veterinary, forensic, and ecological importance due to its ability to cause myiasis, colonise human remains, and displace native Diptera. However, little is known about their upper thermal tolerance, which could be used to better predict their invasion potential.
2. We investigated the upper thermal tolerance of C. rufifacies exposed to different temperatures (20–45 °C), times (1–6 h), and nutrients (no food or water, water only, or a food-water mixture) for both sexes and two age ranges (young = 6–8 days post pupal emergence; old = 9–11 days post pupal emergence).
3. As temperature or duration increased, the probability of knockdown increased (0–100% at 20 and 45 °C and from 41 to 75% at 1 and 6 h), while the probability of survival decreased (99–2% at 20 and 45 °C and from 75 to 28% at 1 and 6 h). The availability of nutrients increased thermal tolerance at moderate temperatures (40 and 42 °C). Female flies were more thermally tolerant than males (probability of knockdown = 49% vs 58%; probability of survival = 58% vs 46%). Thermal tolerance did not differ by age.
4. These data reveal details about the upper thermal tolerance for a single population of C. rufifacies, and suggest that environmental and organismal factors ought to be considered in order to make meaningful predictions about the invasion potential of C. rufifacies in North America.

     

Microsatellite DNA loci from the Diamondback terrapin (Malaclemys terrapin)

We describe polymerase chain recation (PCR) primers and conditions to amplify one dinucleotide and five tetranucleotide microsatellite DNA loci isolated from the Diamondback terrapin (Malaclemys terrapin). The PCR primers were tested on 21 terrapins from Cape Romain, SC, USA. The microsatellite primers developed yielded a high number of alleles (8–14) and high observed heterozygosities (0.57–1.0).     

Identification of Residues in the 558-Loop of Factor VIIIa A2 Subunit That Interact with Factor IXa

Factor VIIIa is comprised of A1, A2, and A3C1C2 subunits. Several lines of evidence have identified the A2 558-loop as interacting with factor IXa. The contributions of individual residues within this region to inter-protein affinity and cofactor activity were assessed following alanine scanning mutagenesis of residues 555–571 that border or are contained within the loop. Variants were expressed as isolated A2 domains in Sf9 cells using a baculovirus construct and purified to >90%. Two reconstitution assays were employed to determine affinity and activity parameters. The first assay reconstituted factor Xase using varying concentrations of A2 mutant and fixed levels of A1/A3C1C2 dimer purified from wild type (WT), baby hamster kidney cell-expressed factor VIII, factor IXa, and phospholipid vesicles to determine the inter-molecular K_d for A2. The second assay determined the K_d for A2 in factor VIIIa by reconstituting various A2 and fixed levels of A1/A3C1C2. Parameter values were determined by factor Xa generation assays. WT A2 expressed in insect cells yielded similar K_d and k_cat values following reconstitution as WT A2 purified from baby hamster kidney cell-expressed factor VIII. All A2 variants exhibited modest if any increases in K_d values for factor VIIIa assembly. However, variants S558A, V559A, D560A, G563A, and I566A showed >9-fold increases in K_d for factor Xase assembly, implicating these residues in stabilizing A2 association with factor IXa. Furthermore, variants Y555A, V559A, D560A, G563A, I566A, and D569A showed >80% reduction in k_cat for factor Xa generation. These results identify residues in the 558-loop critical to interaction with factor IXa in Xase.