Identification and Characterization of the Lipid Transport System in the Tarantula Grammostola rosea

Lipids due to its hydrophobic nature are transported in the hemolymph mainly by lipoproteic fractions. In the present work we studied the lipoproteic fractions present in the hemolymph of the spider Grammostola rosea. Through ultracentrifugation two lipoproteic fractions are isolated, one of high density named Gr-HDL (δ = 1.13 - 1.15 g/ml) and the other of very high density called Gr-VHDL (δ = 1.24 - 1.27 g/ml) Gr-VHDL in hemolymph is majority in relation to Gr-HDL. In this sense Gr-VHDL fraction has 98.6% of hemolymphatic proteins, and 89.3% of lipids presents in the hemolymph. Both lipoproteic fractions possess phospholipids such as majority lipids (phosphatidylcholine and phosphatidylethanolamine) and 18:1, 16:0, 18:2 and 18:0 as the major fatty acids. In order to confirm the role played by lipoproteic fractions in vitro assays with different 14C-lipid were performed. It was observed that Gr-VHDL takes up mainly free fatty acids and triacylglycerols unlike that observed for Gr-HDL in relation to phosphatidylcholine. Through electrophoresis it was observed that Gr-VHDL has three proteins: a predominant band of 68 kDa and two others of 99 and 121 kDa. Gr-HDL displayed a predominant band of 93 kDa, and other minority of 249 kDa. In conclusion, this study reports lipid characterization of the lipoproteic fractions present in the hemolymph of the tarantula, G. rosea. The role of each lipoproteic fraction in relation to lipid up- take is sustained by in vitro assays. Similarities and differences are found when it is compared to lipoproteins of only the three species of spiders studied.Fil: Laino, Aldana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Cunningham, Monica Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Suarez, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Garcia, Carlos Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; Argentin

Back to the future: a simplified and intuitive derivation of the Lotka-Euler equation

The Lotka-Euler equation is a mathematical expression used to study population dynamics and growth, particularly in the context of demography and ecology. The growth rate $\lambda$ is the speed at which $N$ individuals produce their offspring, resulting in a population size of $N R_0$, where $R_0$ is the average offspring size. It is essentially a birth process, and here it is shown that by reversing the process to a death process, in which $N R_0$ individuals die at a rate $\lambda^{-1}$, the derivation of the Lotka-Euler equation becomes more intuitive and direct, both in discrete and continuous time.Comment: Just a not

Antibiotic cement spacer for isolated medial wall acetabular deficiency in the setting of infected hip arthroplasty

Periprosthetic joint infections remain challenging for orthopaedic surgeons. These are typically treated with 2-stage revision with an antibiotic spacer and arthroplasty reimplantation after infection eradication. We report a novel technique to create an antibiotic cement spacer construct in the setting of significant acetabular medial wall destruction due to osteolysis and infection. The medial wall of the acetabulum was reconstructed using antibiotic cement with 2 screws acting as a rebar. An acetabular liner was then cemented into place forming a cement construct similar to a reconstruction cage in function. This technique created a firm acetabular construct that allowed for the placement of a stable articulating spacer. The spacer allowed for infection eradication and was successfully converted into a revision total hip arthroplasty

The Practice of Overlapping Surgery Is Safe in Total Knee and Hip Arthroplasty

Background: Overlapping surgery occurs when a surgeon performs 2 procedures in an overlapping time frame. This practice is commonplace in the setting of total joint arthroplasty and is intended to increase patient access to experienced surgeons, improve efficiency, and advance the surgical competence of surgeons and trainees. The practice of overlapping surgery has been questioned because of safety and ethical concerns. As the literature is scarce on this issue, we evaluated the unplanned hospital readmission and reoperation rates associated with overlapping and non-overlapping total joint arthroplasty procedures. Methods: We reviewed 3,290 consecutive primary total knee and hip arthroplasty procedures that had been performed between November 2010 and July 2016 by 2 fellowship-trained senior surgeons at a single institution. Overlapping surgery was defined as the practice in which the attending surgeon performed a separate procedure in another room with an overlapping room time of at least 30 minutes. Patient baseline characteristics and 90-day rates of complications, readmissions, and reoperations were compared between overlapping and non-overlapping procedures. Subanalyses also were done on patients with a body mass index (BMI) of ≥30 kg/m2 and those with an American Society of Anesthesiologists (ASA) score of 3 or 4. The level of significance was set at 0.05. Results: Of the 2,833 procedures that met the inclusion criteria, 57% (1,610) were overlapping and 43% (1,223) were non-overlapping. Baseline demographics, BMI, and ASA scores were similar between the groups. No significant differences were found between the overlapping and non-overlapping procedures in terms of the 90-day rates of complications (5.2% vs. 6.6%, respectively; p = 0.104), unplanned readmissions (3.4% vs. 4.3%; p = 0.235), or reoperations (3.1 vs. 3.1; p = 1.0) in the analysis of the entire cohort or in subgroup analyses of obese patients and patients with an ASA score of 3 or 4. The total mean operating room time was 5.8 minutes higher for overlapping procedures. Conclusions: Overlapping procedures showed no increase in terms of the 90-day rates of complications, readmissions, or reoperations when compared with non-overlapping procedures. There was just over a 5-minute increase in mean operating room time for overlapping procedures. Our data suggest that overlapping surgery does not lead to detrimental outcomes following total knee arthroplasty or total hip arthroplasty. Future investigations evaluating patient-oriented outcomes and satisfaction are warranted. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence

Immobilization of arsenic from copper smelter waste

Arsenic is an inconvenient impurity for copper smelters and its problematic its bound to worsen as concentrates become dirtier. Air emissions are prevented during the off-gas treatment so it deports to liquid effluents and dusts. From effluents it cannot be removed easily together with other metals and specific removal needs to be considered. At industrial level the preferred choice is precipitation and copper smelters thus seek precipitates that are safe enough for inexpensive landfill disposal. The literature review identified the most common methods used by industry as well as more novel proposals to remove arsenic from solution. When precipitates or other types of solids are still too hazardous for safe disposal, it is possible to stabilise them with other methods discussed. The experimental work tested one solid stabilisation approach, vitrification, on hazardous copper smelter waste. Next, after producing an arsenic bearing solution similar to copper smelter effluents by leaching the same waste, five precipitation methods were tested: high iron arsenical ferrihydrite, a two-step process using aluminium and iron, arsenate hydroxyapatite, gypsum seeded scorodite and ferrous arsenate (symplesite). The short term leaching behaviour of the solids was tested with 24 hour bottle tests performed at different pH conditions. The results showed that all methods produced solids somewhat safer than the original one, but only the symplesite and two step precipitation methods have resulted in solids safe enough for landfill disposal. A preliminary cost estimation shows that these methods could be competitive with existing processes, while producing a safer solid. Regarding vitrification of the current waste, even though the particular conditions of the test were unable to produce a safe enough solid, the waste proved amenable to the process

Nonlinear Exchange Rate Predictability

We study whether the nonlinear behavior of the real exchange rate can help us account for the lack of predictability of the nominal exchange rate. We construct a smooth nonlinear error-correction model that allows us to test the hypotheses of nonlinear predictability of the nominal exchange rate and nonlinear behavior on the real exchange rate in the context of a fully specified cointegrated system. Using a panel of 19 countries and three numeraires, we find evidence of nonlinear predictability of the nominal exchange rate and of nonlinear mean reversion of the real exchange rate. Out-of-sample Theil's U-statistics show a higher forecast precision of the nonlinear model than the one obtained with a random walk specification. Although the robustness of the out-of-sample results over different forecast windows is somewhat limited, we are able to obtain significant predictability gains--from a parsimonious structural model with PPP fundamentals--even at short-run horizons.Exchange rates; Predictability; Nonlinearities; Purchasing power parity