Characteristics of Exocytosis and Endocytosis in Photoreceptors

Photoreceptors signal changes in light intensity to downstream retinal neurons through the exocytosis of glutamate-containing synaptic vesicles. The maintenance of the vesicle exocytosis and endocytosis process is essential for ongoing synaptic signaling. This study investigated the properties of exocytosis and endocytosis in photoreceptors and their role in ongoing neurotransmission. I used electrophysiology and imaging techniques to study the properties of vesicle exocytosis and endocytosis in photoreceptors. First, we examined baseline release in photoreceptors that occurs in the absence of depolarizing stimulation. We measured mEPSCs in whole cell patch clamp recordings from horizontal cells. After inhibiting Ca2+ influx and efflux and increasing intracellular Ca2+ buffering, we found that mEPSCs persisted, indicating that a portion of the baseline release occurs by a Ca2+-independent mechanism. Presynaptic recordings from rods and cones confirmed that glutamate release continues after Ca2+ is blocked. There was a decrease in frequency and amplitude of Ca2+-independent events. Visualization of individual exocytosis events by TIRF microscopy showed that Ca2+-independent release can occur at non-ribbon release sites. Following exocytosis, vesicles are retrieved by endocytosis and reenter the vesicle cycle. We measured exocytosis and endocytosis from membrane capacitance changes evoked by depolarizing steps in voltage clamped rods. Endocytosis in rods was rapid relative to other neurons with an average time constant of Ca2+ influx. Together these studies identified the sites and vesicle pools involved in Ca2+-independent baseline release from photoreceptors and found that endocytosis kinetics in rods are rapid and depend upon endocytic load and local Ca2+ levels

Interpreting Biological Similarity: Ongoing Challenges for Diverse Decision Makers

Similarity is an elusive and complicated concept facing comparisons of biological molecules, as even minute changes to a molecule\u27s structure can dramatically affect its function in the body. Yet the flood of biologic drugs on the market will increasingly force these similarity comparisons. These concerns are particularly relevant to two groups of drugs: families of biologic drugs that closely resemble each other in structure and function, here termed similar-impact biologics, and the biosimilars, which are intended to closely approximate generic forms of biologic drugs. In bringing biologic drugs to the market, manufacturers are likely to face dual obstacles: FDA approval and patent protection. These hurdles are somewhat in tension with each other. The more similar biosimilars are to their pioneer counterparts, the more easily they may advance to market via the Biologics Price Competition and Innovation Act\u27s ( BPCIA ) new accelerated approval pathway. While the FDA has provided some guidance about how much similarity is likely to suffice, the standard is not yet clearly defined. In contrast, the more similar two drugs are to one another, the less likely that they will be able to obtain patent protection. Further, biologic drugs pose special issues when considering various legal factors required for patentability. Resolving these questions for the optimal benefit of all stakeholders requires both fundamental institutional competency and a willingness on the part of decision makers to engage with difficult scientific questions. This Note explores these ongoing challenges, with particular focus on the clinical and litigation history of the TNFá inhibitors Humira, Enbrel, and Remicade

Interpreting Biological Similarity: Ongoing Challenges for Diverse Decision Makers

Similarity is an elusive and complicated concept facing comparisons of biological molecules, as even minute changes to a molecule\u27s structure can dramatically affect its function in the body. Yet the flood of biologic drugs on the market will increasingly force these similarity comparisons. These concerns are particularly relevant to two groups of drugs: families of biologic drugs that closely resemble each other in structure and function, here termed similar-impact biologics, and the biosimilars, which are intended to closely approximate generic forms of biologic drugs. In bringing biologic drugs to the market, manufacturers are likely to face dual obstacles: FDA approval and patent protection. These hurdles are somewhat in tension with each other. The more similar biosimilars are to their pioneer counterparts, the more easily they may advance to market via the Biologics Price Competition and Innovation Act\u27s ( BPCIA ) new accelerated approval pathway. While the FDA has provided some guidance about how much similarity is likely to suffice, the standard is not yet clearly defined. In contrast, the more similar two drugs are to one another, the less likely that they will be able to obtain patent protection. Further, biologic drugs pose special issues when considering various legal factors required for patentability. Resolving these questions for the optimal benefit of all stakeholders requires both fundamental institutional competency and a willingness on the part of decision makers to engage with difficult scientific questions. This Note explores these ongoing challenges, with particular focus on the clinical and litigation history of the TNFá inhibitors Humira, Enbrel, and Remicade

The Relationship Between Vitamin D Status and Body Mass Index in a Racially Diverse Urban Population of Male and Female Pre- and Early Adolescents

Objectives: To assess the association between serum 25(OH)D and body mass index (BMI) in pre- and early-adolescents and to determine whether this association varies by demographic/clinical characteristics. Methods: Vitamin D status was determined using serum 25(OH)D in healthy pre- and early adolescents in Pittsburgh, PA (deficiency=/mL, insufficiency=12-/mL, sufficiency=≥20 ng/mL). Adiposity was quantified using BMI percentile (normal=\u3c85th, overweight=\u3e85th-95th, obese=\u3e95th). The relationship between serum 25(OH)D and adiposity was assessed in the total population and after stratification by gender, race, Fitzpatrick skin type, age, and Tanner stage. Results: 294 children (mean age 10.2 + 2.1 years; 60% African American; median serum 25(OH)D=27.0 ng/mL) were studied. Serum 25(OH)D was significantly lower in obese (n=72) vs. overweight (n=48) and normal weight (n=171) participants at 23.6, 29.5, and 28.2 ng/mL, respectively; p=0.015. This trend remained significant for early adolescents but did not differ after stratification by other demographic/clinical characteristics. A significant negative correlation was found between BMI and serum 25(OH)D (r = -0.315; p=0.000). Regression analysis predicted that 25% of the variance in serum 25(OH)D levels was attributed to BMI, gender, race, skin type, age, pubertal status, daily vitamin D and calcium intake, sun exposure, and sunscreen use, with Tanner stage being the only significant independent predictor. Conclusions: A significant inverse association between serum 25(OH)D and adiposity was observed in a population of pre- and early adolescents. This relationship was stronger in early adolescents. A meta-analysis to further explore this association in pediatric populations is warranted

Patients as researchers - innovative experiences in UK National Health Service research

Consumer involvement is an established priority in UK health and social care service development and research. To date, little has been published describing the process of consumer involvement and assessing ‘consumers’ contributions to research. This paper provides a practical account of the effective incorporation of consumers into a research team, and outlines the extent to which they can enhance the research cycle; from project development and conduct, through data analysis and interpretation, to dissemination. Salient points are illustrated using the example of their collaboration in a research project. Of particular note were consumers’ contributions to the development of an ethically enhanced, more robust project design, and enriched data interpretation, which may not have resulted had consumers not been an integral part of the research team

Discovery of the Cadmium Isotopes

Thirty-seven cadmium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.Comment: to be published in Atomic Data and Nuclear Data Table

Overview and status of the 0.5NA EUV microfield exposure tool at Berkeley Lab

A 0.5-NA extreme ultraviolet micro-field exposure tool has been installed and commissioned at beamline 12.0.1.4 of the Advanced Light Source synchrotron facility at Lawrence Berkeley National Laboratory. Commissioning has demonstrated a patterning resolution of 13 nm half-pitch with annular 0.35-0.55 illumination; a patterning resolution of 8 nm half-pitch with annular 0.1-0.2 illumination; critical dimension (CD) uniformity of 0.7 nm 1σ on 16 nm nominal CD across 80% of the 200 um x 30 um aberration corrected field of view; aerial image vibration relative to the wafer of 0.75 nn RMS and focus control and focus stepping better than 15 nm

Achieving diffraction-limited performance on the Berkeley MET5

The Berkeley MET5, funded by EUREKA, is a 0.5-NA EUV projection lithography tool located at the Advanced Light Source at Berkeley National Lab. Wavefront measurements of the MET5 optic have been performed using a custom in-situ lateral shearing interferometer suitable for high-NA interferometry. In this paper, we report on the most recent characterization of the MET5 optic demonstrating an RMS wavefront 0.31 nm, and discuss the specialized mask patterns, gratings, and illumination geometries that were employed to accommodate the many challenges associated with high-NA EUV interferometry

Lateral mobility of L-type calcium channels in synaptic terminals of retinal bipolar cells.

PURPOSE: Efficient and precise release of glutamate from retinal bipolar cells is ensured by the positioning of L-type Ca(2+) channels close to release sites at the base of the synaptic ribbon. We investigated whether Ca(2+) channels at bipolar cell ribbon synapses are fixed in position or capable of moving in the membrane. METHODS: We tracked the movements of individual L-type Ca(2+) channels in bipolar cell terminals after labeling channels with quantum dots (QDs) attached to α(2)δ(4) accessory Ca(2+) channel subunits via intermediary antibodies. RESULTS: We found that individual Ca(2+) channels moved within a confined domain of 0.13-0.15 μm(2) in bipolar cell terminals, similar to ultrastructural estimates of the surface area of the active zone beneath the ribbon. Disruption of actin expanded the confinement domain indicating that cytoskeletal interactions help to confine channels at the synapse, but the relatively large diffusion coefficients of 0.3-0.45 μm(2)/s suggest that channels are not directly anchored to actin. Unlike photoreceptor synapses, removing membrane cholesterol did not change domain size, indicating that lipid rafts are not required to confine Ca(2+) channels at bipolar cell ribbon synapses. CONCLUSIONS: The ability of Ca(2+) channels to move within the presynaptic active zone suggests that regulating channel mobility may affect release from bipolar cell terminals