Self-assembling peptide hydrogels for articular cartilage repair

Osteoarthritis affects millions of people globally, with damage to articular cartilage causing pain and altered mechanics during articulation. The treatment for late stage osteoarthritis is surgical intervention ultimately leading to total joint replacements. These treatments are not ideal for younger or more active patients so there is a clinical need for an early stage intervention treatment to reduce or stop the progression of osteoarthritis. It has been reported that there is a correlation between the loss of glycosaminoglycans (GAGs) from within osteoarthritic cartilage and the changes in biomechanics of the cartilage. It is hypothesized that the re-introduction of GAGs into early stage osteoarthritic cartilage through the use of permanent linkage and integration into a self-assembling peptide hydrogel matrix which could penetrate the cartilage tissue would potentially restore the resistance to deformation observed in osteoarthritic cartilage. Initially, synthetic self-assembling peptide-chondroitin sulfate (CS) conjugates were synthesized through utilizing copper-catalyzed click chemistry and subsequently characterized. The chosen peptide-CS conjugates were then incorporated into self-assembling peptide hydrogels and the morphologies and gel properties were investigated and evaluated in terms of the closest resemblance to the natural properties of the surrounding cartilage into which the hydrogels would be eventually injected. The best hydrogel candidates were then taken forward to be injected into a GAG depleted early stage osteoarthritic porcine cartilage model developed by Andres Barco (University of Leeds) where a severely GAG depleted state had been produced through a succession of surfactant and phosphate buffered saline washes. The hydrogels were doped with fluorescently labelled material which integrated into the hydrogel matrix, then injected into the cartilage tissue in a monomeric state. The hydrogels then self-assembled in situ and the deformation of the tissue was measured through creep indentation. The introduction of the peptide-CS conjugate showed significant restoration of resistance to deformation

Behavior of larval walleye

High resolution cinematography was used to observe larval walleye (Stizostedion vitreum) behavior in laboratory aquaria. Observations focused on gas bladder inflation (GBI), first-feeding, and cannibalism. Four discrete phases of developmental behavior were observed: surface suspension (from hatch to 40 TU); a GBI phase (40-100 TU) with constant, rapid anquilliform swimming at the water surface; a first-feeding phase (100-240 TU) with slower, more subcarangiform swimming throughout the water column in search of food; and, a fully exogenous phase (after 240 TU) when the larvae move to the bottom of culture tanks and easily consume sinking feed particles that come within close range (TU = ∘C x days posthatch). First-feeding behavior was typical of a predatory fish with four discrete elements: prey fixation, tracking, an S-shaped strike posture, and a high speed open mouth strike. This behavior was identical for nonliving feed particles, live Daphnia, or when attacking other larvae;Microcinematography provides direct visual evidence of physostomous GBI mechanisms showing a larva penetrating the surface tension and a larva with an air bubble in the gut which is pushed against the ventral edge of the gas bladder where it disappears. The addition of turbidity to culture water provided nonedge larval distribution and faster swimming speeds which significantly increased GBI and growth rates. In tests of three water temperatures on development and behavior, higher temperatures provided significantly increased swimming speed during the GBI phase which seemed to account for significantly greater growth and viability;Cannibalistic behavior was indicated as a major cause of larval mortality. Successful cannibalism only resulted from caudal fin attacks and accounted for about 26% of the overall mortality. Our observations indicate that injuries from attack seizures of the head, opercle, pectoral fin, and trunk area, which greatly outnumbered successful caudal attacks, are a major cause of mortality in tank culture of walleye. Cannibalism and larval attack frequency were strongly correlated with mortality rates and only occurred during the first-feeding phase

Forced Migration After Paris COP21: Evaluating the Climate Change Displacement Coordination Facility

Climate change represents, perhaps, the greatest challenge of the twenty-first century. As temperatures and sea levels rise, governments around the world will face massive and unprecedented human displacement that international law currently has no mechanism to address. While estimates vary, the scope of the migration crisis that the world will face in the coming decades is startling. In addition to losing their homes, climate change migrants, under current law, will encounter a refugee system governed by a decades-old Refugee Convention that offers neither protection nor the right to resettle in a more habitable place. Armed with the most recent developments in international climate change law following the December 2015 Paris climate conference (COP21), this Note considers which of the existing bodies in the United Nations is best equipped to address forced migration caused by climate change. Inspired by the negotiations leading up to the Paris Conference, this Note advocates for a Climate Change Displacement Coordination Facility, housed within the United Nations Framework Convention on Climate Change (UNFCCC), to protect the rights of displaced persons. Finally, this Note maps out an institutional architecture and a long-term vision for a Displacement Coordination Facility. As opposed to an amendment of the 1951 Refugee Convention or a new rights-based treaty for climate migration, a Facility housed within the UNFCCC provides the greatest possible flexibility, autonomy, and cultural retention for climate change migrants while still protecting their essential human rights

Self-assembling peptide hydrogels for articular cartilage repair

Osteoarthritis affects millions of people globally, with damage to articular cartilage causing pain and altered mechanics during articulation. The treatment for late stage osteoarthritis is surgical intervention ultimately leading to total joint replacements. These treatments are not ideal for younger or more active patients so there is a clinical need for an early stage intervention treatment to reduce or stop the progression of osteoarthritis. It has been reported that there is a correlation between the loss of glycosaminoglycans (GAGs) from within osteoarthritic cartilage and the changes in biomechanics of the cartilage. It is hypothesized that the re-introduction of GAGs into early stage osteoarthritic cartilage through the use of permanent linkage and integration into a self-assembling peptide hydrogel matrix which could penetrate the cartilage tissue would potentially restore the resistance to deformation observed in osteoarthritic cartilage. Initially, synthetic self-assembling peptide-chondroitin sulfate (CS) conjugates were synthesized through utilizing copper-catalyzed click chemistry and subsequently characterized. The chosen peptide-CS conjugates were then incorporated into self-assembling peptide hydrogels and the morphologies and gel properties were investigated and evaluated in terms of the closest resemblance to the natural properties of the surrounding cartilage into which the hydrogels would be eventually injected. The best hydrogel candidates were then taken forward to be injected into a GAG depleted early stage osteoarthritic porcine cartilage model developed by Andres Barco (University of Leeds) where a severely GAG depleted state had been produced through a succession of surfactant and phosphate buffered saline washes. The hydrogels were doped with fluorescently labelled material which integrated into the hydrogel matrix, then injected into the cartilage tissue in a monomeric state. The hydrogels then self-assembled in situ and the deformation of the tissue was measured through creep indentation. The introduction of the peptide-CS conjugate showed significant restoration of resistance to deformation

Wind tunnel balance

A flow-through balance is provided which includes a non-metric portion and a metric portion which form a fluid-conducting passage in fluid communication with an internal bore in the sting. The non-metric and metric portions of the balance are integrally connected together by a plurality of flexure beams such that the non-metric portion, the metric portion and the flexure beams form a one-piece construction which eliminates mechanical hysteresis between the non-metric and the metric portion. The system includes structures for preventing the effects of temperature, pressure and pressurized fluid from producing asymmetric loads on the flexure beams. A temperature sensor and a pressure sensor are located within the fluid-conducting passage of the balance. The system includes a longitudinal bellows member connected at two ends to one of the non-metric portion and the metric portion and at an intermediate portion thereof to the other of (1) and (2). A plurality of strain gages are mounted on the flexure beams to measure strain forces on the flexure beams. The flexure beams are disposed so as to enable symmetric forces on the flexure beams to cancel out so that only asymmetric forces are measured as deviations by the strain gages

Residential Water Conservation: Seasonal Rates and Non-Linear Tariffs

With drought conditions and climate change creating an increasingly pressing issue, water conservation has become profoundly important. This work quantifies the effectiveness of residential water conservation programs, namely non-linear tariff functions and seasonal rates, at inducing household water customers to conserve water. The analysis of non-linear tariffs and seasonal rates commences through a clustering study, measuring consumption at certain kink points in pricing. If customers respond to prices by reducing consumption, then one should observe a bunching of customers who consume just below kink points where the marginal price of water increases. I use detailed customer-level data on monthly water consumption from a water utility in Texas to test for the behavioral response to discrete increases in the marginal price of water. This work concludes that consumers in this region do not respond to price changes at the kink points in non-linear tariff functions in a statistically significant way

Evaluation of the Introduction of Florida Bass into an Oklahoma Reservoir Receiving a Heated Effluent

Zoolog