Loss-of-function mutations in growth differentiation factor-1 (GDF1) are associated with congenital heart defects in humans

Congenital heart defects (CHDs) are among the most common birth defects in humans (incidence 8-10 per 1,000 live births). Although their etiology is often poorly understood, most are considered to arise from multifactorial influences, including environmental and genetic components, as well as from less common syndromic forms. We hypothesized that disturbances in left-right patterning could contribute to the pathogenesis of selected cardiac defects by interfering with the extrinsic cues leading to the proper looping and vessel remodeling of the normally asymmetrically developed heart and vessels. Here, we show that heterozygous loss-of-function mutations in the human GDF1 gene contribute to cardiac defects ranging from tetralogy of Fallot to transposition of the great arteries and that decreased TGF- beta signaling provides a framework for understanding their pathogenesis. These findings implicate perturbations of the TGF- beta signaling pathway in the causation of a major subclass of human CHDs.     

Pair approximations and the inclusion of indirect transmission: theory and application to between farm transmission of Salmonella

The spatial-temporal dynamics of farm animal diseases depend both on disease specific processes and the underlying contact network between farms. Indirect transmission via free-living bacteria in the environment is an important transmission route and contributes significantly to the dynamics. The pair-wise model has been developed to include both direct transmission and indirect transmission via free stages. The model is compared with stochastic simulations of epidemics on contact networks. The network framework is applied to the investigation of the epidemiological dynamics of between-herd transmission of Salmonella spp. The main results help to explain differences in observed epidemiological patterns and to identify possible causes for different strains of Salmonella developing so much variation in their infection dynamics in UK dairy herds. Numerical results show that shorter infectious period, more persistent immune response and more rapid removal of faeces result in a lower prevalence of infection and a greater tendency for (damped) oscillation. A possible control strategy is consequently suggested. Furthermore, the effect of network structure on long-term dynamics is examined.     

Immune correlates of aging in outdoor-housed captive rhesus macaques (<Emphasis Type="Italic">Macaca mulatta</Emphasis>)

Background

Questions remain about whether inflammation is a cause, consequence, or coincidence of aging. The purpose of this study was to define baseline immunological characteristics from blood to develop a model in rhesus macaques that could be used to address the relationship between inflammation and aging. Hematology, flow cytometry, clinical chemistry, and multiplex cytokine/chemokine analyses were performed on a group of 101 outdoor-housed captive rhesus macaques ranging from 2 to 24 years of age, approximately equivalent to 8 to 77 years of age in humans.

Results

These results extend earlier reports correlating changes in lymphocyte subpopulations and cytokines/chemokines with increasing age. There were significant declines in numbers of white blood cells (WBC) overall, as well as lymphocytes, monocytes, and polymorphonuclear cells with increasing age. Among lymphocytes, there were no significant declines in NK cells and T cells, whereas B cell numbers exhibited significant declines with age. Within the T cell populations, there were significant declines in numbers of CD4+ naïve T cells and CD8+ naïve T cells. Conversely, numbers of CD4+CD8+ effector memory and CD8+effector memory T cells increased with age. New multiplex analyses revealed that concentrations of a panel of ten circulating cytokines/chemokines, IFNγ, IL1b, IL6, IL12, IL15, TNFα, MCP1, MIP1α, IL1ra, and IL4, each significantly correlated with age and also exhibited concordant pairwise correlations with every other factor within this group. To also control for outlier values, mean rank values of each of these cytokine concentrations in relation to age of each animal and these also correlated with age.

Conclusions

A panel of ten cytokines/chemokines were identified that correlated with aging and also with each other. This will permit selection of animals exhibiting relatively higher and lower inflammation status as a model to test mechanisms of inflammation status in aging with susceptibility to infections and vaccine efficacy.

     

Adult:Child Differences in the Intraspecies Uncertainty Factor: A Case Study Using Lead

Adults and children differ in their susceptibility to the toxic effects of lead. Lead was therefore used as a case study to evaluate intraspecies differences by comparing the adult and child minimal Lowest Observed Adverse Effect Level (LOAEL) or the No Observed Adverse Effect Level (NOAEL), allowing an evaluation of the ten-fold intraspecies uncertainty factor (UF). The lead intakes (in µg/kg/d) necessary to achieve target blood lead (PbB) levels reflecting the minimal LOAEL or NOAEL were determined using biokinetic slope factors (BKSFs), which relate lead uptake to PbB levels. The analyses assumed chronic, low-level oral exposure to lead, and the response of a typical adult and child. Child analyses used a target geometric mean (GM) PbB of 4.6?µg/dL (95% of population <10?µg/dL), resulting in lead intakes of 1.9?µg/kg/day (assuming 100% soluble lead) and 4.9?µg/kg/day (assuming 25% soluble lead and 75 % soil lead). Adult analyses assumed intake of 100 % soluble lead, and used target GM PbB levels of 4.2?µg/dL (95% of population <11.1 µg/dL) and 11.4?µg/dL (95% of population <30?µg/dL), resulting in lead intakes of 1.9?µg/kg/day and 5.1?µg/kg/day, respectively. The results indicate that despite the greater vulnerability of young children to the effects of lead as compared to adults, the minimal LOAEL or NOAEL for lead is remarkably similar between children and adults. In this case, the application of a tenfold intraspecies uncertainty factor to adjust the adult minimal LOAEL or NOAEL for a child would be unnecessary, despite the well-established vulnerability of children to lead.     

Cluster of differentiation antigen 4 (CD4) endocytosis and adaptor complex binding require activation of the CD4 endocytosis signal by serine phosphorylation

Cluster of differentiation antigen 4 (CD4), the T lymphocyte antigen receptor component and human immunodeficiency virus coreceptor, is down-modulated when cells are activated by antigen or phorbol esters. During down-modulation CD4 dissociates from p56(lck), undergoes endocytosis through clathrin-coated pits, and is then sorted in early endosomes to late endocytic organelles where it is degraded. Previous studies have suggested that phosphorylation and a dileucine sequence are required for down-modulation. Using transfected HeLa cells, in which CD4 endocytosis can be studied in the absence of p56(lck), we show that the dileucine sequence in the cytoplasmic domain is essential for clathrin-mediated CD4 endocytosis. However, this sequence is only functional as an endocytosis signal when neighboring serine residues are phosphorylated. Phosphoserine is required for rapid endocytosis because CD4 molecules in which the cytoplasmic domain serine residues are substituted with glutamic acid residues are not internalized efficiently. Using surface plasmon resonance, we show that CD4 peptides containing the dileucine sequence bind weakly to clathrin adaptor protein complexes 2 and 1. The affinity of this interaction is increased 350- to 700-fold when the peptides also contain phosphoserine residues.     

Structure-based design of novel dihydroisoquinoline BACE-1 inhibitors that do not engage the catalytic aspartates

The structure–activity relationship of a series of dihydroisoquinoline BACE-1 inhibitors is described. Application of structure-based design to screening hit 1 yielded sub-micromolar inhibitors. Replacement of the carboxylic acid of 1 was guided by X-ray crystallography, which allowed the replacement of a key water-mediated hydrogen bond. This work culminated in compounds such as 31, which possess good BACE-1 potency, excellent permeability and a low P-gp efflux ratio.     

Impact of an Interdisciplinary Deep Brain Stimulation Screening Model on Post-Surgical Complications in Essential Tremor Patients

Objective

To investigate the relationship of our interdisciplinary screening process on post-operative unintended hospitalizations and quality of life.

Background

There are currently no standardized criteria for selection of appropriate Deep Brain Stimulation candidates and little hard data exists to support the use of any singular method.

Methods

An Essential Tremor cohort was selected from our institutional Deep Brain Stimulation database. The interdisciplinary model utilized seven specialties who pre-operatively screened all potential Deep Brain Stimulation candidates. Concerns for surgery raised by each specialty were documented and classified as none, minor, or major. Charts were reviewed to identify unintended hospitalizations and quality of life measurements at 1 year post-surgery.

Results

Eighty-six percent (44/51) of the potential screened candidates were approved for Deep Brain Stimulation. Eight (18%) patients had an unintended hospitalization during the follow-up period. Patients with minor or major concerns raised by any specialty service had significantly more unintended hospitalizations when compared to patients without concerns (75% vs. 25%, p < 0.005). The rate of hospitalization revealed a direct relationship to the “level of concern”; ranging from 100% if major concerns, 42% if minor concerns, and 7% if no concerns raised, p = 0.001. Quality of life scores significantly worsened in patients with unintended hospitalizations at 6 (p = 0.046) and 12 months (p = 0.027) when compared to baseline scores. No significant differences in tremor scores between unintended and non-unintended hospitalizations were observed.

Conclusions

The number and level of concerns raised during interdisciplinary Deep Brain Stimulation screenings were significantly related to unintended hospitalizations and to a reduced quality of life. The interdisciplinary evaluation may help to stratify risk for these complications. However, data should be interpreted with caution due to the limitations of our study. Further prospective comparative and larger studies are required to confirm our results.     

High-resolution proton and carbon-13 NMR of membranes: why sonicate?

We have obtained high-field (11.7-T) proton and carbon-13 Fourier transform (FT) nuclear magnetic resonance (NMR) spectra of egg lecithin and egg lecithin-cholesterol (1:1) multibilayers, using "magic-angle" sample spinning (MASS) techniques, and sonicated egg lecithin and egg lecithin-cholesterol (1:1) vesicles, using conventional FT NMR methods. Resolution of the proton and carbon-13 MASS NMR spectra of the pure egg lecithin samples is essentially identical with that of sonicated samples, but spectra of the unsonicated lipid, using MASS, can be obtained very much faster than with the more dilute, sonicated systems. With the 1:1 lecithin-cholesterol systems, proton MASS NMR spectra are virtually identical with conventional FT spectra of sonicated samples, while with 13C NMR, we demonstrate that most 13C nuclei in the cholesterol moiety can be monitored, even though these same nuclei are essentially invisible, i.e., are severely broadened, in the corresponding sonicated systems. In addition, 13C MASS NMR, spectra can again be recorded much faster than with sonicated samples, due to concentration effects. Taken together, these results strongly suggest there will seldom be need in the future to resort to ultrasonic disruption of lipid bilayer membranes in order to obtain high-resolution proton or carbon-13 NMR spectra.     

Phytoplankton and bacterial assemblages in ballast water of U.S. military ships as a function of port of origin, voyage time, and ocean exchange practices

We characterized the physical/chemical conditions and the algal and bacterial assemblages in ballast water from 62 ballast tanks aboard 28 ships operated by the U.S. Military Sealift Command and the Maritime Administration, sampled at 9 ports on the U.S. West Coast and 4 ports on the U.S. East Coast. The ballast tank waters had been held for 2–176 days, and 90% of the tanks had undergone ballast exchange with open ocean waters. Phytoplankton abundance was highly variable (grand mean for all tanks, 3.21 × 10⁴ viable cells m⁻³; median, 7.9 × 10³ cells m⁻³) and was unrelated to physical/chemical parameters, except for a positive relationship between centric diatom abundance and nitrate concentration. A total of 100 phytoplankton species were identified from the ballast tanks, including 23 potentially harmful taxa (e.g. Chaetoceros concavicornis, Dinophysis acuminata, Gambierdiscus toxicus, Heterosigma akashiwo, Karlodinium veneficum, Prorocentrum minimum, Pseudo-nitzschia multiseries). Assemblages were dominated by chain-forming diatoms and dinoflagellates, and viable organisms comprised about half of the total cells. Species richness was higher in ballast tanks with coastal water, and in tanks containing Atlantic or Pacific Ocean source waters rather than Indian Ocean water. Total and viable phytoplankton numbers decreased with age of water in the tanks. Diversity also generally decreased with water age, and tanks with ballast water age >33 days did not produce culturable phytoplankton. Abundance was significantly higher in tanks with recently added coastal water than in tanks without coastal sources, but highly variable in waters held less than 30 days. Bacterial abundance was significantly lower in ballast tanks with Atlantic than Pacific Ocean source water, but otherwise was surprisingly consistent among ballast tanks (overall mean across all tanks, 3.13 ± 1.27 × 10¹¹ cells m⁻³; median, 2.79 × 10¹¹ cells m⁻³) and was unrelated to vessel type, exchange status, age of water, environmental conditions measured, or phytoplankton abundance. At least one of four pathogenic eubacteria (Listeria monocytogenes, Escherichia coli, Mycobacterium spp., Pseudomonas aeruginosa) was detected in 48% of the ballast tanks, but toxigenic strains of Vibrio cholerae were not detected. For ships with tanks of similar ballasting history, the largest source of variation in phytoplankton and bacteria abundance was among ships; for ships with tanks of differing ballasting histories, and for all ships/tanks considered collectively, the largest source of variation was within ships. Significant differences in phytoplankton abundance, but not bacterial abundance, sometimes occurred between paired tanks with similar ballasting history; hence, for regulatory purposes phytoplankton abundance cannot be estimated from single tanks only. Most tanks (94%) had adequate records to determine the source locations and age of the ballast water and, as mentioned, 90% had had ballast exchange with open-ocean waters. Although additional data are needed from sediments that can accumulate at the bottom of ballast tanks, the data from this water-column study indicate that in general, U.S. Department of Defense (DoD) ships are well managed to minimize the risk for introduction of harmful microbiota. Nevertheless, abundances of viable phytoplankton with maximum dimension >50 μm exceeded proposed International Maritime Organization standards in 47% of the ballast tanks sampled. The data suggest that further treatment technologies and/or alternative management strategies will be necessary to enable DoD vessels to comply with proposed standards.