Effects of hypophysectomy and thyroidectomy on salt balance in the plethodontid salamanders,Desmognathus fuscus andDesmognathus monticola

Summary Hypophysectomy significantly reduced serum sodium levels inDesmognathus fuscus andD. monticola. Prolactin, corticosterone or aldosterone replacement failed to restore serum sodium to control levels. Hypophysectomy also led to decreases in in vitro integumental potential difference and shortcircuit current, which were not restored to control levels by prolactin or corticosterone. Thyroidectomy significantly reduced the level of serum sodium inD. monticola, but it increased in vitro potential difference and short-circuit current. Thyroxine treatment of either hypophysectomized or thyroidectomizedD. monticola completely restored serum sodium, potential difference and short-circuite current to control levels.     

In vitro long-term performance study of a near-infrared fluorescence affinity sensor for glucose monitoring

The long-term in vitro performance of a fluorescence affinity sensor for transdermal blood glucose monitoring was investigated. Affinity binding of fluorescently labeled concanavalin A (ConA) was used in this application, as previously described by Ballerstadt and Schultz [Anal. Chem. 17 (2000) 4185-4192). In this paper, the fluorescence emission of the sensor was extended to the near infrared (670 nm) using Alexa647 as the fluorochrome conjugated to concanavalin A. Sensors were alternately exposed to glucose solutions having concentrations of 2.5 and 20 mM with a dwell time of 3 h. The optical output of the sensors was monitored over a 4-month period. The sensors showed an initial increase in fluorescence over the first 3-4 weeks before gradually decreasing, with an approximately linear drop of 25% per month. In order to understand the reasons for the decrease in fluorescence output, further experiments were conducted, including time-dependent membrane leakage tests, solubility tests of ConA, temperature-dependent activity tests of ConA, and fluorescence photo-bleaching tests. From these results, it became evident that the decrease in fluorescence was not due to denaturation of the ConA. The most likely cause was leakage of the fluorescently labeled ConA through the interface between the outer sealant and the membrane. This problem is considered to be solvable and future publications will address this issue. Extrapolation of the experimental data suggests that a leak-proof sensor would be remarkably stable with a fluorescence decrease of only 15% over a 1-year period.     

Closing the loop between neurobiology and flight behavior in Drosophila

Fruit flies alter flight direction by generating rapid stereotyped turns called saccades. Using a combination of tethered and free-flight methods, both the aerodynamic mechanisms and the sensory triggers for saccades have been investigated. The results indicate that saccades are elicited by visual expansion, and are brought about by remarkably subtle changes in wing motion. Mechanosensory feedback from the fly's 'gyroscope' complements visual cues to terminate saccades, as well as to stabilize forward flight. Olfactory stimuli elicit tonic increases in wingbeat amplitude and frequency but do not alter the time course or magnitude of visual reflexes.     

Papillomavirus-like particles induce acute activation of dendritic cells

The role of viral structural proteins in the initiation of adaptive immune responses is poorly understood. To address this issue, we focused on the effect of noninfectious papillomavirus-like particles (VLPs) on dendritic cell (DC) activation. We found that murine bone marrow-derived dendritic cells (BMDCs) effectively bound and rapidly internalized bovine papillomavirus VLPS: Exposure to fully assembled VLPs of bovine papillomavirus, human papillomavirus (HPV)16 or HPV18, but not to predominately disordered HPV16 capsomers, induced acute phenotypic maturation of BMDCS: Structurally similar polyomavirus VLPs bound to the DC surface and were internalized, but failed to induce maturation. DCs that had incorporated HPV16 VLPs produced proinflammatory cytokines IL-6 and TNF-alpha; however, the release of these cytokines was delayed relative to LPS activation. Production of IL-12p70 by VLP-exposed DCs required the addition of syngeneic T cells or rIFN-gamma. Finally, BMDCs pulsed with HPV16 VLPs induced Th1-dominated primary T cell responses in vitro. Our data provide evidence that DCs respond to intact papillomavirus capsids and that they play a central role in VLP-induced immunity. These results offer a mechanistic explanation for the striking ability of papillomavirus VLP-based vaccines to induce potent T and B cell responses even in the absence of adjuvant.     

Methods to Measure the Impact of Home,Social, and Sexual Neighborhoods of Urban Gay,Bisexual, and Other Men Who Have Sex with Men

Men who have sex with men (MSM) accounted for 61% of new HIV diagnoses in the United States in 2010. Recent analyses indicate that socio-structural factors are important correlates of HIV infection. NYCM2M was a cross-sectional study designed to identify neighborhood-level characteristics within the urban environment that influence sexual risk behaviors, substance use and depression among MSM living in New York City. The sample was recruited using a modified venue-based time-space sampling methodology and through select websites and mobile applications. This paper describes novel methodological approaches used to improve the quality of data collected for analysis of the impact of neighborhoods on MSM health. Previous research has focused predominately on residential neighborhoods and used pre-determined administrative boundaries (e.g., census tracts) that often do not reflect authentic and meaningful neighborhoods. This study included the definition and assessment of multiple neighborhoods of influence including where men live (home neighborhood), socialize (social neighborhood) and have sex (sexual neighborhood). Furthermore, making use of technological advances in mapping, we collected geo-points of reference for each type of neighborhood and identified and constructed self-identified neighborhood boundary definitions. Finally, this study collected both perceived neighborhood characteristics and objective neighborhood conditions to create a comprehensive, flexible and rich neighborhood-level set of covariates. This research revealed that men perceived their home, social and sexual neighborhoods in different ways. Few men (15%) had the same home, social and sexual neighborhoods; for 31%, none of the neighborhoods was the same. Of the three types of neighborhoods, the number of unique social neighborhoods was the lowest; the size of sexual neighborhoods was the smallest. The resultant dataset offers the opportunity to conduct analyses that will yield context-specific and nuanced understandings of the relations among neighborhood space, and the well-being and health of urban MSM.     

EVL regulates VEGF receptor‐2 internalization and signaling in developmental angiogenesis

Endothelial tip cells are essential for VEGF‐induced angiogenesis, but underlying mechanisms are elusive. The Ena/VASP protein family, consisting of EVL, VASP, and Mena, plays a pivotal role in axon guidance. Given that axonal growth cones and endothelial tip cells share many common features, from the morphological to the molecular level, we investigated the role of Ena/VASP proteins in angiogenesis. EVL and VASP, but not Mena, are expressed in endothelial cells of the postnatal mouse retina. Global deletion of EVL (but not VASP) compromises the radial sprouting of the vascular plexus in mice. Similarly, endothelial‐specific EVL deletion compromises the radial sprouting of the vascular plexus and reduces the endothelial tip cell density and filopodia formation. Gene sets involved in blood vessel development and angiogenesis are down‐regulated in EVL‐deficient P5‐retinal endothelial cells. Consistently, EVL deletion impairs VEGF‐induced endothelial cell proliferation and sprouting, and reduces the internalization and phosphorylation of VEGF receptor 2 and its downstream signaling via the MAPK/ERK pathway. Together, we show that endothelial EVL regulates sprouting angiogenesis via VEGF receptor‐2 internalization and signaling.     

Determination of trimethoprim in low-volume human plasma by liquid chromatography.

Trimethoprim is an anti-infective agent used in the treatment of urinary and respiratory tract infections and mild to moderate pneumocystis carinii pneumonia. Trimethoprim is also a selective in vitro inhibitor of cytochrome P450 2C8 and may have utility as an in vivo inhibitor of this enzyme. A simplified high performance liquid chromatography (HPLC) method was developed to determine trimethoprim in human plasma. Samples are processed by protein precipitation with perchloric acid and chromatographic separation is achieved on a Synergi Polar-RP column (4 micron, 150 mm x 4.6 mm) using a mobile phase consisting of 50 mM ammonium formate-acetonitrile-methanol (pH=3.0; 90:6:4 (v/v/v)). Detection is monitored at 280 nm. Intra- and inter-day precision ranged from 1.1 to 1.9 and 0.9 to 4.1%, respectively. The assay is simple, economical, precise, and is directly applicable to human studies involving steady state trimethoprim pharmacokinetics.