Sequential conversion of the glutathionyl side chain of slow reacting substance (SRS) to cysteinyl-glycine and cysteine in rat basophilic leukemia cells stimulated with A-23187

In rat basophilic leukemia (RBL-1) cells stimulated with A-23187, the major slow reacting substance (SRS) species contain glutathione, cysteinyl-glycine, or cysteine in their side chains, corresponding or closely related to leukotrienes LTC₄, LTD₄, and LTE₄, respectively.³ Evidence is presented that most of the SRS produced during the first few minutes of stimulation by the ionophore has a glutathionyl side chain which is sequentially converted to cysteinyl-glycine and cysteine.     

Growth in Coculture Stimulates Metabolism of the Phenylurea Herbicide Isoproturon by Sphingomonas sp. Strain SRS2

Metabolism of the phenylurea herbicide isoproturon by Sphingomonas sp. strain SRS2 was significantly enhanced when the strain was grown in coculture with a soil bacterium (designated strain SRS1). Both members of this consortium were isolated from a highly enriched isoproturon-degrading culture derived from an agricultural soil previously treated regularly with the herbicide. Based on analysis of the 16S rRNA gene, strain SRS1 was assigned to the β-subdivision of the proteobacteria and probably represents a new genus. Strain SRS1 was unable to degrade either isoproturon or its known metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, or 4-isopropyl-aniline. Pure culture studies indicate that Sphingomonas sp. SRS2 is auxotrophic and requires components supplied by association with other soil bacteria. A specific mixture of amino acids appeared to meet these requirements, and it was shown that methionine was essential for Sphingomonas sp. SRS2. This suggests that strain SRS1 supplies amino acids to Sphingomonas sp. SRS2, thereby leading to rapid metabolism of ¹⁴C-labeled isoproturon to ¹⁴CO₂ and corresponding growth of strain SRS2. Proliferation of strain SRS1 suggests that isoproturon metabolism by Sphingomonas sp. SRS2 provides unknown metabolites or cell debris that supports growth of strain SRS1. The role of strain SRS1 in the consortium was not ubiquitous among soil bacteria; however, the indigenous soil microflora and some strains from culture collections also stimulate isoproturon metabolism by Sphingomonas sp. strain SRS2 to a similar extent.     

A Spatially Explicit Model of the Wild Hog for Ecological Risk Assessment Activities at the Department of Energy's Savannah River Site

In North America, wild hogs (Sus scrofa) are both sought after as prime game and despised due to their detrimental impacts to the environment from their digging and rooting behavior. They are also a potentially useful indicator species for environmental health for both ecological- and human-based risk assessments. An inductive approach was used to develop probabilistic resource selection models using logistic regression to quantify the likelihood of hogs being in any area of the Department of Energy's 805 km² Savannah River Site (SRS) in west-central South Carolina. These models were derived by using available SRS hog hunt data from 1993–2000 and a Geographic Information System database describing the habitat structure of the SRS. The model's significant parameters indicated that wild hogs preferred hardwoods and avoided pine and shrubby areas. Further, landscape metric analyses revealed that hogs preferred areas with large complex patch areas and low size variation. These resource selection models were then utilized to better estimate exposure of wild hogs to radionuclides and metals in a disturbed riparian ecosystem on the SRS using two different possible diets based on food availability. Contaminant exposure can be better estimated using these resource selection models than has been previously possible, because past practices did not consider home range and habitat utilization probability in heterogeneously contaminated habitats. Had these models not been used, risk calculations would assume that contaminated areas were utilized 100% of the time, thus overestimating exposure by a factor of up to 25.     

Arylsulfatase inactivation of slow reacting substance. Evidence for proteolysis as a major mechanism when ordinary commercial preparations of the enzyme are used

Type II B arylsulfatases are known to inactivate slow reacting substance (SRS), but the mechanism is unclear. In the present study, ordinary commercial preparations of Sigma limpet arylsulfatase largely inactivated the glutathionyl and cysteinyl-glycyl forms of SRS, but the cysteinyl form of SRS was largely resistant to the enzyme. Evidence is presented which established that a major mechanism for the inactivation of the glutathionyl and cysteinyl-glycyl SRS types, at least by the particular enzyme preparations we have studied, involves cleavage of the glycine moiety from the sulfur containing side chain. This was confirmed by digestion studies with glutathione itself. In addition, there is ome evidence to indicate that the enzyme may destabilize the double bond structure of the SRS molecule, contributing to the overall inactivation.     

Slow reacting substances from ionophore A23187-stimulated basophilic leukemia cells and peritoneal mast cells in the rat. I. Purification and comparison during sequential sephadex LH-20 and thin layer chromatography.

Radiolabeled slow reacting substance (SRS) from rat basophilic leukemia cells (RBL-1) or rat peritoneal mast cells was generated by stimulation with the divalent cation ionophore A23187 in the presence of [1^?14C]-arachidonic acid (AA). These radiolabeled SRSs were purified by sequential adsorption, gel filtration and partition chromatography on Sephadex LH-20 with correspondence of bio- and radioactivities. Two-dimensional high performance thin layer chromatography of the active principles continued to show comigration of bio- and radioactivities. RBL-1 and mast cells incorporated [¹⁴C]-AA into bioactive SRS which are analogous based upon similar behavior during purification.     

Ecological Effects of Metals in Streams on a Defense Materials Processing Site in South Carolina,USA

The Savannah River Site (SRS) is a 780 km² U.S. Department of Energy facility near Aiken, South Carolina, established in 1950 to produce nuclear materials. SRS streams are “integrators” that potentially receive water transportable contaminants from all sources within their drainage basins, necessitating a watershed approach to organize contaminant distribution data and characterize the effects of multiple contaminants on aquatic organisms. This study used several lines-of-evidence to assess the ecological effects of metals in SRS streams, including contaminant exposure models for apex predators and bioassessments of fish and macroinvertebrate assemblages. Concentrations of metals in sediments, fish, and water were elevated in streams affected by SRS operations, but contaminant exposure models for the river otter Lontra Canadensis and belted kingfisher Ceryle alcyon indicated that toxicological reference values were exceeded only by Hg and Al. Macroinvertebrate assemblage structure was unrelated to sediment metal concentrations. Fish assemblage data were inconclusive. This study indicated that (1) modeling studies and field bioassessments provide a complementary basis for addressing the individual and cumulative effects of contaminants, (2) habitat effects must be controlled when assessing contaminant impacts, (3) sensitivity analyses of contaminant exposure models can help to apportion sampling effort, and (4) most individual metals in SRS streams are unlikely to have significant ecological effects.     

Spatial and temporal patterns of aboveground net primary productivity (ANPP) along two freshwater-estuarine transects in the Florida Coastal Everglades

We present here a 4-year dataset (2001–2004) on the spatial and temporal patterns of aboveground net primary production (ANPP) by dominant primary producers (sawgrass, periphyton, mangroves, and seagrasses) along two transects in the oligotrophic Florida Everglades coastal landscape. The 17 sites of the Florida Coastal Everglades Long Term Ecological Research (FCE LTER) program are located along fresh-estuarine gradients in Shark River Slough (SRS) and Taylor River/C-111/Florida Bay (TS/Ph) basins that drain the western and southern Everglades, respectively. Within the SRS basin, sawgrass and periphyton ANPP did not differ significantly among sites but mangrove ANPP was highest at the site nearest the Gulf of Mexico. In the southern Everglades transect, there was a productivity peak in sawgrass and periphyton at the upper estuarine ecotone within Taylor River but no trends were observed in the C-111 Basin for either primary producer. Over the 4 years, average sawgrass ANPP in both basins ranged from 255 to 606 g m⁻² year⁻¹. Average periphyton productivity at SRS and TS/Ph was 17–68 g C m⁻² year⁻¹ and 342–10371 g C m⁻² year⁻¹, respectively. Mangrove productivity ranged from 340 g m⁻² year⁻¹ at Taylor River to 2208 g m⁻² year⁻¹ at the lower estuarine Shark River site. Average Thalassia testudinum productivity ranged from 91 to 396 g m⁻² year⁻¹ and was 4-fold greater at the site nearest the Gulf of Mexico than in eastern Florida Bay. There were no differences in periphyton productivity at Florida Bay. Interannual comparisons revealed no significant differences within each primary producer at either SRS or TS/Ph with the exception of sawgrass at SRS and the C−111 Basin. Future research will address difficulties in assessing and comparing ANPP of different primary producers along gradients as well as the significance of belowground production to the total productivity of this ecosystem.     

红景天苷对运动后自由基和能量代谢改变的影响

目的:探讨红景天苷在运动过程中对自由基和能量代谢相关指标的作用,从抗氧化系统、能量代谢系统等方面研究红景天苷抗运动性疲劳的机制。方法:本研究采用小鼠运动模型,40只雄性小鼠随机取分为4组(n=10):红景天苷运动组,红景天苷安静组,运动对照组,安静对照组。红景天苷运动组和安静组两组以150 mg/(kg.d)的红景天苷灌胃给药,运动和安静对照组两组以同样体积蒸馏水灌胃,连续给药2周;末次灌胃30 min后,运动组进行无负重游泳120 min,然后测定与运动性疲劳相关的生化指标。结果:研究结果表明,红景天苷能够提高运动小鼠肝脏内超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)等抗氧化酶活性,降低丙二醛(MDA)含量;红景天苷具有稳定运动小鼠血糖,增加肝、肌糖原储备,防止长时间运动后血糖和肝、肌糖原水平降低的作用;红景天苷可提高运动小鼠血浆总胆固醇(TC)、甘油三酯(TG)及游离脂肪酸(FFA)的水平,有影响不同状态下的脂肪代谢,促进脂肪利用的作用。结论:红景天苷对运动过程中自由基和能量代谢改变的影响是其抗运动性疲劳的机制之一。     

Fingerprint‐to‐CH stretch continuously tunable high spectral resolution stimulated Raman scattering microscope

Stimulated Raman scattering (SRS) microscopy is a label‐free method generating images based on chemical contrast within samples, and has already shown its great potential for high‐sensitivity and fast imaging of biological specimens. The capability of SRS to collect molecular vibrational signatures in bio‐samples, coupled with the availability of powerful statistical analysis methods, allows quantitative chemical imaging of live cells with sub‐cellular resolution. This application has substantially driven the development of new SRS microscopy platforms. Indeed, in recent years, there has been a constant effort on devising configurations able to rapidly collect Raman spectra from samples over a wide vibrational spectral range, as needed for quantitative analysis by using chemometric methods. In this paper, an SRS microscope which exploits spectral shaping by a narrowband and rapidly tunable acousto‐optical tunable filter (AOTF) is presented. This microscope enables spectral scanning from the Raman fingerprint region to the Carbon‐Hydrogen (CH)‐stretch region without any modification of the optical setup. Moreover, it features also a high enough spectral resolution to allow resolving Raman peaks in the crowded fingerprint region. Finally, application of the developed SRS microscope to broadband hyperspectral imaging of biological samples over a large spectral range from 800 to 3600 cm^?1, is demonstrated.     

Feasibility and potential advantages using VMAT in SRS metastasis treatments

BackgroundUtilization of stereotactic radiosurgery (SRS) for brain metastases (BM) has become the technique of choice as opposed to whole brain radiation therapy (WBRT). The aim of this work is to evaluate the feasibility and potential benefits in terms of normal tissue (NT) and dose escalation of volumetric modulated arc therapy (VMAT) in SRS metastasis treatment. A VMAT optimization procedure has therefore been developed for internal dose scaling which minimizes planner dependence.Materials and methodsFive patient-plans incorporating treatment with frame-based SRS with dynamic conformal arc technique (DA) were re-planned for VMAT. The lesions selected were between 4–6 cm³. The same geometry used in the DA plans was maintained for the VMAT cases. A VMAT planning procedure was performed attempting to scale the dose in inner auxiliary volumes, and to explore the potential for dose scaling with this technique. Comparison of dose-volume histogram (DVH) parameters were obtained.ResultsVMAT allows a superior NT sparing plus conformity and dose scaling using the auxiliary volumes. The VMAT results were significantly superior in NT sparing, improving both the V₁₀ and V₁₂ values in all cases, with a 2–3 cm³ saving. In addition, VMAT improves the dose coverage D₉₅ by about 0.5 Gy. The objective of dose escalation was achieved with VMAT with an increment of the Dmean and the Dmedian of about 2 Gy.ConclusionsThis work shows a benefit of VMAT in SRS treatment with significant NT sparing. A VMAT optimization procedure, based on auxiliary inner volumes, has been developed, enabling internal dose escalation.     

Fatty acid structural requirements for leukotriene biosynthesis

Utilizing a variety of fatty acids, differing in chain length, degree and position of unsaturation, we investigated the substrate specificity for the enzymatic production of biologically active slow reacting substances (SRS) and of the other leukotrienes. A cellfree enzyme system obtained from RBL-1 cells was used in this study. The primary structural requirement observed for the conversion by this lipoxygenase enzyme system was a Δ^5,8,11 unsaturation in a polyenoic fatty acid. Such fatty acids as 20:4 (5,8,11,14), 20:5 (5,8,11,14,17), 20:3 (5,8,11), 19:4 (5,8,11,14) and 18:4 (5,8,11,14) were readily converted to compounds that comigrated with 5-HETE and 5,12-DiHETE and to biologically active SRS. Chain length did not have an influence on the formation of these hydroxyacids. Fatty acids with the initial unsaturation at Δ⁴, Δ⁶, Δ⁷ or Δ⁸ were a poor substrate for the leukotriene enzyme system. Therefore, this lipoxygenase pathway in leukocytes is quite different from the lipoxygenase in platelets which does not exhibit this specificity.     

Slow reacting substance (SRS) from ionophore A23187-stimulated peritoneal mast cells of the normal rat. II. Evidence for a precursor role of arachidonic acid and further purification.

The generation of slow reacting substance (SRS) from ionophore A23187-stimulated rat peritoneal mast cells was enhanced by arachidonic acid (AA). This SRS generation was inhibited by 5,8,11,14-eicosatetraynoic acid (ETYA), an acetylenic analogue of AA and an inhibitor of both fatty acid cyclooxygenase and lipoxygenase. Indomethacin, a fatty acid cyclooxgenase inhibitor, had an enhancing effect upon SRS generation. This suggests SRS generation occurred through an ETYA sensitive step--perhaps a lipoxygenase. Radiolabel from [14C]-AA was incorporated into SRS with comigration of radioactivity and bioreactivity in silicic acid and thin layer chromatographies. Upon silicic acid chromatography, the active principle was eluted in the methanol fraction. Two-dimensional thin layer chromatography revealed chromatographic separation from other known spasmogenic substances and phospholipids. Mast cell SRS was found to display physiochemical properties similar to those of rat basophilic leukemia cell SRS, namely: that mast cell SRS generation was 1) enhanced by arachidonic acid; 2) inhibited by ETYA but not by indomethacin; 3) incorporation of [14C]-AA into the active principle; and 4) similar behavior during purification in silicic acid and thin layer chromatographies.     

Growth in coculture stimulates metabolism of the phenylurea herbicide isoproturon by Sphingomonas sp. strain SRS2

Metabolism of the phenylurea herbicide isoproturon by Sphingomonas sp. strain SRS2 was significantly enhanced when the strain was grown in coculture with a soil bacterium (designated strain SRS1). Both members of this consortium were isolated from a highly enriched isoproturon-degrading culture derived from an agricultural soil previously treated regularly with the herbicide. Based on analysis of the 16S rRNA gene, strain SRS1 was assigned to the beta-subdivision of the proteobacteria and probably represents a new genus. Strain SRS1 was unable to degrade either isoproturon or its known metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, or 4-isopropyl-aniline. Pure culture studies indicate that Sphingomonas sp. SRS2 is auxotrophic and requires components supplied by association with other soil bacteria. A specific mixture of amino acids appeared to meet these requirements, and it was shown that methionine was essential for Sphingomonas sp. SRS2. This suggests that strain SRS1 supplies amino acids to Sphingomonas sp. SRS2, thereby leading to rapid metabolism of (14)C-labeled isoproturon to (14)CO(2) and corresponding growth of strain SRS2. Proliferation of strain SRS1 suggests that isoproturon metabolism by Sphingomonas sp. SRS2 provides unknown metabolites or cell debris that supports growth of strain SRS1. The role of strain SRS1 in the consortium was not ubiquitous among soil bacteria; however, the indigenous soil microflora and some strains from culture collections also stimulate isoproturon metabolism by Sphingomonas sp. strain SRS2 to a similar extent.     

CO2-induced ion and fluid transport in human retinal pigment epithelium

In the intact eye, the transition from light to dark alters pH, [Ca²⁺], and [K] in the subretinal space (SRS) separating the photoreceptor outer segments and the apical membrane of the retinal pigment epithelium (RPE). In addition to these changes, oxygen consumption in the retina increases with a concomitant release of CO₂ and H₂O into the SRS. The RPE maintains SRS pH and volume homeostasis by transporting these metabolic byproducts to the choroidal blood supply. In vitro, we mimicked the transition from light to dark by increasing apical bath CO₂ from 5 to 13%; this maneuver decreased cell pH from 7.37 ± 0.05 to 7.14 ± 0.06 (n = 13). Our analysis of native and cultured fetal human RPE shows that the apical membrane is significantly more permeable (≈10-fold; n = 7) to CO₂ than the basolateral membrane, perhaps due to its larger exposed surface area. The limited CO₂ diffusion at the basolateral membrane promotes carbonic anhydrase–mediated HCO₃ transport by a basolateral membrane Na/nHCO₃ cotransporter. The activity of this transporter was increased by elevating apical bath CO₂ and was reduced by dorzolamide. Increasing apical bath CO₂ also increased intracellular Na from 15.7 ± 3.3 to 24.0 ± 5.3 mM (n = 6; P < 0.05) by increasing apical membrane Na uptake. The CO₂-induced acidification also inhibited the basolateral membrane Cl/HCO₃ exchanger and increased net steady-state fluid absorption from 2.8 ± 1.6 to 6.7 ± 2.3 µl × cm⁻² × hr⁻¹ (n = 5; P < 0.05). The present experiments show how the RPE can accommodate the increased retinal production of CO₂ and H₂O in the dark, thus preventing acidosis in the SRS. This homeostatic process would preserve the close anatomical relationship between photoreceptor outer segments and RPE in the dark and light, thus protecting the health of the photoreceptors.     

Formation of the cysteinyl form of slow reacting substance (leukotriene E4) in human plasma

The two major species of slow reacting substance (SRS) contain either a glutathionyl or cysteinyl-glycyl side chain. Incubation of these SRS's with undiluted or diluted (usually 1:10 or 1:50) human plasma at 37°C resulted in marked losses of smooth muscle contracting activity due primarily to conversion of their oligopeptide side chains to cysteine.     

In vivo estimation of the short-range stiffness of cross-bridges from joint rotation

Short-range stiffness (SRS) is a mechanical property of muscles that is characterized by a disproportionally high stiffness within a short length range during both lengthening and shortening movements. SRS is attributed to the cross-bridges and is beneficial for stabilizing a joint during, e.g., postural conditions. Thus far, SRS has been estimated mainly on isolated mammalian muscles. In this study we presented a method to estimate SRS in vivo in the human wrist joint.SRS was estimated at joint level in the angular domain (N m/rad) for both flexion and extension rotations of the human wrist in nine healthy subjects. Wrist rotations of 0.15 rad at 3 rad/s were imposed at eight levels of voluntary contraction ranging from 0 to 2.1 N m by means of a single axis manipulator.Flexion and extension SRS of the wrist joint was estimated consistently and accurately using a dynamic nonlinear model that was fitted onto the recorded wrist torque. SRS increased monotonically with torque in a way consistent with previous studies on isolated muscles.It is concluded that in vivo measurement of joint SRS represents the population of coupled cross-bridges in wrist flexor and extensor muscles. In its current form, the presented technique can be used for clinical applications in many neurological and muscular diseases where altered joint torque and (dissociated) joint stiffness are important clinical parameters.     

A Spatially Explicit Model to Predict Radiocesium Body Burdens of White-Tailed Deer on the U.S. Department of Energy's Savannah River Site

We developed a spatially explicit exposure model to interpolate and predict radiocesium (¹³⁷Cs) body burdens found in white-tailed deer (Odocoileus virginianus) on the U.S. Department of Energy's (USDOE) Savannah River Site (SRS) to gain insight into and differentiate between the main contributing sources of this radionuclide for use in harvest management strategies that focus on minimizing human risk. Hunting has been allowed from permanent stands as a mechanism to manage the deer herd since 1965. All animals are monitored in the field for gross beta and gamma activity levels, providing a spatially explicit dataset. The models described here use the relative locations of the hunt-stands to predict ¹³⁷Cs exposure distributions. We used kriging to create an interpolation surface using average white-tailed deer body burdens. Cross-validations of the kriged surfaces differentiated between sources of ¹³⁷Cs and where deer reside on the SRS. The kriged surfaces, coupled with additional regression analyses, provide a comprehensive assessment of deer's ¹³⁷Cs body burdens with predictive capability that quantifies the scale at which such investigations can be conducted. Although the models are local in scale, the methods presented here can be used as a template for other large areas that are being monitored for radioactive fallout.     

Prostaglandin release by slow reacting substance from guinea pig and human lung tissue

Slow reacting substance (SRS) injected into the pulmonary artery released prostaglandin E (PGE) and F_2α (PGF_2α) and the 15-keto-13, 14-dihydro PG metabolites from non-sensitized and ovalbumin sensitized, isolated, perfused guinea pig lungs. PGs were also released from lungs incubated with SRS. Sensitized lungs released more PGs in both types of preparations. Indomethacin inhibited the effect of SRS. Passively sensitized human lung fragments, in parallel to guinea pig lung, released PGE, PGF_2α and the metabolites when incubatted with SRS or antigen. In experiments, SRS and arachidonic acid given intravenously increased the airway insufflation pressure in anesthetized guinea pigs. These effects, but not the action of injected PGF_2α and histamine, were abolished by indomethacin. The results indicate that one of the modes of SRS action is by release of PGs, and are consistent with the hypothesis that PGs are predominantly “secondary” mediators (in the temporal sense) of the antigen-antibody reaction.     

Time motion study to evaluate the impact of flattening filter free beam on overall treatment time for frameless intracranial radiosurgery using Varian TrueBeam® linear accelerator

BackgroundThe aim was to study the impact of the flattening filter free (FFF) beam on overall treatment time for frameless intracranial radiosurgery using TrueBeam^® LINAC.The development of frameless stereotactic radiosurgery (SRS) is possible due to the incorporation of image guidance in the delivery of treatment. It is important to analyze the cost and benefits of FFF beams for treating SRS by understanding the impact of FFF beams in reducing the treatment time.Materials and methodsDynamic conformal arc (DCA ) and volumetric arc therapy (VMAT) plans were generated using 6 MV with a flattening filter (FF) and FFF beams. Overall treatment time was divided into beam on time (BOT) and beam off time (BFT). Percentage beam on time reduction (PBOTR) and Percentage total time reduction (PTTR) factors were defined for the comparison.ResultsBOT reduction was observed to be significant for higher dose per fraction but subjected to the treatment technique and modulation differences. PBOTR values are much higher than PTTR values. The 39.9% of PBOTR resulted in only 8% PTTR for DCA and 65.3% resulted in 15.9% PTTR for VMAT.ConclusionMajor BFT was utilized for imaging and verification. FFF beam significantly reduced the beam on time and was found to be most effective if the fractional dose was as high as that for SRS. Newly defined PBOTR and PTTR factors are very useful indicators to evaluate the efficacy of FFF beams in terms of time reduction.