Photopolymerization and Mass-Independent Sulfur Isotope Fractionations in Carbon Disulfide

Irradiation of gaseous carbon disulfide [CS2(g)] at 313 nanometers produces a dark brown aerosol of (CS2)x. Its thermal decomposition products include disulfur (S2), carbon monosulfide (CS), and (CS)x. The photopolymerization process is accompanied by a large mass-independent isotopic fractionation of sulfur (a 5 to 10 per mil sulfur-33 excess and a 61 to 84 per mil sulfur-36 deficit). Excess sulfur-33 has been observed in several classes of meteorites. Photochemical production of (CS2)x may be important in the origin and evolution of cosmochemical environments such as the presolar nebula, meteorites, asteroids, and planetary atmospheres.     

Mouse B-type lamins are required for proper organogenesis but not by embryonic stem cells

B-type lamins, the major components of the nuclear lamina, are believed to be essential for cell proliferation and survival. We found that mouse embryonic stem cells (ESCs) do not need any lamins for self-renewal and pluripotency. Although genome-wide lamin-B binding profiles correlate with reduced gene expression, such binding is not directly required for gene silencing in ESCs or trophectoderm cells. However, B-type lamins are required for proper organogenesis. Defects in spindle orientation in neural progenitor cells and migration of neurons probably cause brain disorganizations found in lamin-B null mice. Thus, our studies not only disprove several prevailing views of lamin-Bs but also establish a foundation for redefining the function of the nuclear lamina in the context of tissue building and homeostasis.     

A molecular dynamics simulation on the self-assembly of ABC triblock copolymers. 2. Effects of block sequence

The effect of block sequence on the self-assembly of ABC-type triblock copolymers in the ordered state is investigated using an isothermal-isobaric molecular dynamics simulation. The block sequence has an important effect on the morphology of ABC triblock copolymers. Different morphologies are observed depending on the block sequence as well as the block composition. The triblock copolymers with the volume fraction of 1:1:1 (f _A=f _B=f _C=0.33) show the three phase and four layered lamellar structures irrespective of the block sequence. The A₃₂B₁₆C₃₂ triblock copolymer withf _B=0.2 shows a morphology in which cylinders of midblock B are formed at the interface between A and C lamellae, whereas the morphology of triblock copolymer B₁₆C₃₂A₃₂ and C₃₂A₃₂B₁₆ show a cylindrical core-shell structure and a lamellar type morphology, respectively. The A₂₀B₄₀C₂₀ triblock copolymer with the block B as a major component shows a tricontinuous structure, whereas both B₄₀C₂₀A₂₀ and C₂₀A₂₀B₄₀ triblock copolymers exhibit the lamellar structures. When the block B has larger volume fraction withf _B=0.75, the matrix is composed of block B, and other two blocks A and C form spherical domains.     

Comparison of sevoflurane and isoflurane anesthetic index in unpremedicated dogs

Anesthetic respiratory effects of sevoflurane (SEVO) were compared with isoflurane (ISO) in unpremedicated dogs. Minimum alveolar concentration (MAC), apneic concentration (AC), and anesthetic index (AI) of SEVO and ISO were determined in eight 1‐year‐old healthy dogs, weighing 19 ± 3 kg (mean ± SEM) in a randomized complete block multiple cross‐over design. Dogs were mask‐induced with either SEVO or ISO in 100% oxygen. Following endotracheal intubation, dogs were instrumented, mechanically ventilated, and MAC was determined using a tail‐clamp method. Next, spontaneous ventilation was re‐established, and anesthetic concentration was increased to determine the AC. Throughout the anesthetic event, heart rate (HR), systolic blood pressure (SAP), mean blood pressure (MAP), diastolic blood pressure (DAP), respiratory rate (RR), end‐tidal carbon dioxide (Pe ′CO₂), and oxyhemoglobin saturation (SpO₂) were recorded at 3‐minute intervals. Following AC determination, AI was calculated as AC/MAC, and dogs were allowed to recover. Each dog was anesthetized four times (twice with ISO and SEVO each) at 1‐week intervals. All data were analyzed using the two‐way anova . Multiple comparisons were performed between ISO and SEVO treatments. Statistical significance was set at p < 0.05. Significant differences were noted between agents for MAC (SEVO, 2.13 ± 0.10%; ISO, 1.38 ± 0.14%; p < 0.0001), AC (SEVO, 7.34 ± 0.13%; ISO, 3.60 ± 0.13%; p < 0.0001), and AI (SEVO, 3.46 ± 0.22; ISO, 2.63 ± 0.14; p = 0.0002). Physiologic parameters were compared between SEVO and ISO at 1MAC, 2MAC, 3MAC, and AC. No differences were noted between SEVO and ISO treatments for cardiovascular parameters (HR, SAP, MAP, DAP). Significant differences were noted, favoring SEVO, for all respiratory parameters (RR, Pe ′CO₂, SpO₂) at increasing MAC multiples. Additionally, regression analysis was conducted for physiologic variable data points. Analysis of Pe ′CO₂ data points demonstrated a significant slope difference of ?6.47 ± 1.02 (B_SEVO ? B_ISO; p < 0.0001; r² = 0.6042) favoring SEVO. While expected dose‐related ventilatory depression was noted for both agents, all the respiratory parameters for SEVO demonstrated less respiratory depression than ISO at equipotent doses. These results indicated that SEVO caused less dose‐dependent ventilatory depression than ISO, having a significantly higher AI and causing less detrimental change in pulmonary parameters at increasing levels of MAC.     

Purification and Identification of an Antioxidative Peptide from Digestive Enzyme Hydrolysis of Cutlassfish Muscle

ABSTRACT

The major objective of this study was to investigate the pepsin digests of cutlassfish muscle for their antioxidant activity. The peptide isolated after 3 h of pepsin hydrolysis demonstrated the highest scavenging activity for both 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals. It also had the highest yield of the isolates with the highest protein content, which was likely related to its higher degree of hydrolysis than the other hydrolysates. The antioxidant peptide purified from the 3 h pepsin hydrolysate indicated the amino acid sequence, Phe-Ser-Gly-Gly-Glu. This study suggests that cutlassfish muscle is an excellent antioxidant source and could be effectively used as a food ingredient and in pharmaceuticals.