Properties and Genesis of Hot Particles from the Chernobyl Reactor Accident

1996 ◽  
Vol 465 ◽  
Author(s):  
Peter Schubert-Bischoff ◽  
Werner Lutze ◽  
Boris E. Burakov
Keyword(s):  
Fission Product ◽  
Specific Activity ◽  
High Specific Activity ◽  
Chemical Compositions ◽  
Fuel Particle ◽  
Reactor Unit ◽  
Hot Particles ◽  
Hot Particle ◽  
Dust Generation ◽  
Wide Range

ABSTRACTOn April 25, 1986, the nuclear reactor Unit 4 (RBMK) at Chernobyl, Ukraine, exploded. Besides molecular species, the fallout contained particles of relatively high specific activity (hot particles) with a wide range of chemical compositions. The composition of a hot particle bears information about its genesis. Particle sizes ranged from a few to 100s of micrometers. Data on a hot particle, found in Berlin, Germany, is presented and discussed in context with earlier measurements on other particles to understand their genesis. The chemical composition was determined by electron probe micro analysis. Our particles are either reactor fuel (one) or fission product alloys (nine). The alloys were formed during normal reactor operation. Strongly varying concentrations of Fe and Ni suggest that at least some of our particles reacted with molten structural material of the reactor. The particles were mobilized by fuel oxidation or fuel dust generation during the accident. The fission product composition can only be explained if we assume that the alloys remained in the solid state in the course of the accident. Some particles may have been ejected during the explosion, others later while the reactor was burning. Activities (103Ru and 106Ru, originally up to 160,000 Bq) of our ten year old particles were re-measured but were no longer detectable. No long-lived γ-emitters were found. The 99Tc activity was calculated and found to only lBq. The γ -spectrum of the fuel particle still shows 137Cs (1 Bq) and 60Co (<1 Bq).

Factor VIII:E113A Represents a High Specific Activity Factor VIII Arising from a Single Point Mutation within a Ca2+ Binding Site.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1725-1725 ◽  
Author(s):  
Hironao Wakabayashi ◽  
Philip J. Fay
Keyword(s):  
Factor Viii ◽  
Specific Activity ◽  
High Specific Activity ◽  
Factor Xa ◽  
Saturation Mutagenesis ◽  
Single Amino Acid ◽  
Single Point Mutation ◽  
Wild Type ◽  
Activity Increase ◽  
Wide Range

Abstract We recently identified an acidic-rich segment in the A1 domain of factor VIII (residues 110-126) that functions in the coordination of Ca2+, an ion necessary for cofactor activity (Wakabayashi et al., J. Biol. Chem.279:12677–12684, 2004). Using Ala-scanning mutagenesis, it was determined that replacement of residue E113 with Ala yielded a factor VIII point mutant that possessed an ~2-fold increased affinity for Ca2+ as compared with wild type, suggesting that this residue did not directly contribute to Ca2+ coordination but rather modulated the affinity of the ion at this site. Furthermore, the E113A factor VIII possessed twice the specific activity of wild type as determined by a one-stage clotting assay. This increased activity was not likely a result of increased affinity for Ca2+, since assays were performed at saturating Ca2+ levels. Saturation mutagenesis at position 113 revealed that substitution at this position with relatively small, nonpolar residues were well-tolerated, whereas replacement with a number of polar or charged residues was detrimental to activity. Ala-substitution yielded the greatest activity increase of ~2-fold and this level was observed over a wide range of factor VIII concentrations. Time course experiments of factor VIII activation following reaction with thrombin revealed similar rates of activation and inactivation of E113A as observed for the wild type. Interestingly, results from factor Xa generation assays using purified reactants showed the mutant possessed <10% greater specific activity than wild type and yielded similar values for Km for substrate factor X, kcat for factor Xa generation and Kd for factor IXa. Thus the single amino acid substitution minimally altered cofactor structure or inter-molecular interactions relating to its participation in factor Xase. These results indicate that mutations within this Ca2+ coordination site may selectively enhance cofactor specific activity as measured in a plasma-based assay compared to activity determined in a purified system. The enhanced activity observed for E113A factor VIII may derive from a subtle alteration in conformation affecting a yet to be identified functional parameter.

scholarly journals Discovery and molecular and biocatalytic properties of hydroxynitrile lyase from an invasive millipede,Chamberlinius hualienensis

2015 ◽  
Vol 112 (34) ◽  
pp. 10605-10610 ◽  
Author(s):  
Mohammad Dadashipour ◽  
Yuko Ishida ◽  
Kazunori Yamamoto ◽  
Yasuhisa Asano
Keyword(s):  
Specific Activity ◽  
Enantiomeric Excess ◽  
High Specific Activity ◽  
Potassium Cyanide ◽  
Aromatic Aldehydes ◽  
Building Blocks ◽  
Industrial Biotechnology ◽  
Hydroxynitrile Lyase ◽  
Wide Range ◽  
Very High

Hydroxynitrile lyase (HNL) catalyzes the degradation of cyanohydrins and causes the release of hydrogen cyanide (cyanogenesis). HNL can enantioselectively produce cyanohydrins, which are valuable building blocks for the synthesis of fine chemicals and pharmaceuticals, and is used as an important biocatalyst in industrial biotechnology. Currently, HNLs are isolated from plants and bacteria. Because industrial biotechnology requires more efficient and stable enzymes for sustainable development, we must continuously explore other potential enzyme sources for the desired HNLs. Despite the abundance of cyanogenic millipedes in the world, there has been no precise study of the HNLs from these arthropods. Here we report the isolation of HNL from the cyanide-emitting invasive millipedeChamberlinius hualienensis, along with its molecular properties and application in biocatalysis. The purified enzyme displays a very high specific activity in the synthesis of mandelonitrile. It is a glycosylated homodimer protein and shows no apparent sequence identity or homology with proteins in the known databases. It shows biocatalytic activity for the condensation of various aromatic aldehydes with potassium cyanide to produce cyanohydrins and has high stability over a wide range of temperatures and pH values. It catalyzes the synthesis of (R)-mandelonitrile from benzaldehyde with a 99% enantiomeric excess, without using any organic solvents. Arthropod fauna comprise 80% of terrestrial animals. We propose that these animals can be valuable resources for exploring not only HNLs but also diverse, efficient, and stable biocatalysts in industrial biotechnology.

ULTRAFILTRATION STUDIES OF STEROID-PROTEIN BINDING

1961 ◽  
Vol 23 (2) ◽  
pp. 129-137 ◽  
Author(s):  
P. S. CHEN ◽  
I. H. MILLS ◽  
F. C. BARTTER
Keyword(s):  
Protein Binding ◽  
Specific Activity ◽  
Binding Protein ◽  
High Specific Activity ◽  
Wide Range

SUMMARY A method is described for determination of the extent of protein binding of steroids by ultrafiltration after addition of radioactively-labelled steroid tracers of high specific activity. Results obtained with specifically labelled 14C-steroids did not differ significantly from those with steroids randomly labelled with tritium. A number of steroids have been studied with this technique. The 'S' shaped curve obtained with some corticosteroids by plotting percentage ultrafilterable against steroid added to the plasma confirmed the presence of the corticosteroid-binding protein which has greater affinity for steroid than albumin. This method of plotting the ultrafiltration data afforded a method of assessing the amount of binding protein (or the number of sites). Cortisone, 17-hydroxy-11-deoxycorticosterone, cortisol, and Δ1 cortisol showed this type of curve. Binding of aldosterone, progesterone and 17-ketosteroids occurred to the same extent in plasma as in 5% albumin. The ultrafilterable fraction of these steroids in plasma was constant over a wide range of total steroid concentration. Binding of testosterone was greater with plasma than with albumin, and did not decrease upon addition of large amounts of testosterone.

Determination of thyrotropin in serum by time-resolved fluoroimmunoassay evaluated.

1985 ◽  
Vol 31 (10) ◽  
pp. 1706-1709 ◽  
Author(s):  
H L Kaihola ◽  
K Irjala ◽  
J Viikari ◽  
V Näntö
Keyword(s):  
Specific Activity ◽  
High Specific Activity ◽  
Reference Interval ◽  
Time Resolved ◽  
Standard Curve ◽  
Highly Sensitive ◽  
Wide Range ◽  
Sandwich Type ◽  
Serum Tsh

Abstract We evaluated a new, highly sensitive time-resolved fluoroimmunoassay for thyrotropin (TSH) in serum. This direct immunometric "sandwich"-type assay involves two monoclonal antibodies against TSH, one immobilized, the other labeled with europium. Extremely high specific activity of the label and the use of labeled antibody in large excess make the method sensitive enough to measure TSH values falling below the normal reference interval. The standard curve is nearly linear over a wide range of TSH concentrations (standard concentrations range from 0.25 to 324 milli-int. units/L). The lowest concentration detectable was 25 micro-int. units/L. The CV for the assay was less than 6% at 0.5 milli-int. unit/L or higher, 11.3% at 0.1 milli-int. unit/L. For a CV of 10% the lower limit of the working range would be around 0.1 milli-int. unit/L. The interassay CV was 6.7 to 11.8% for TSH concentrations of 0.31 to 19.6 milli-int. units/L. The 95% confidence interval for sera from 111 healthy persons was 0.6-3.8 (range 0.3-3.8) milli-int. units/L. For hyperthyroid patients and thyroid cancer patients treated with thyroxin after thyroidectomy, serum TSH values were all below the reference interval (most were less than 25 micro-int. units/L).

scholarly journals The respiratory complexes I from the mitochondria of two Pichia species

2009 ◽  
Vol 422 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Hannah R. Bridges ◽  
Ljuban Grgic ◽  
Michael E. Harbour ◽  
Judy Hirst
Keyword(s):  
Complex I ◽  
Catalytic Mechanism ◽  
Specific Activity ◽  
Proton Translocation ◽  
High Specific Activity ◽  
Nadh Oxidation ◽  
Model Systems ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Protonmotive Force ◽  
Wide Range

NADH:ubiquinone oxidoreductase (complex I) is an entry point for electrons into the respiratory chain in many eukaryotes. It couples NADH oxidation and ubiquinone reduction to proton translocation across the mitochondrial inner membrane. Because complex I deficiencies occur in a wide range of neuromuscular diseases, including Parkinson's disease, there is a clear need for model eukaryotic systems to facilitate structural, functional and mutational studies. In the present study, we describe the purification and characterization of the complexes I from two yeast species, Pichia pastoris and Pichia angusta. They are obligate aerobes which grow to very high cell densities on simple medium, as yeast-like, spheroidal cells. Both Pichia enzymes catalyse inhibitor-sensitive NADH:ubiquinone oxidoreduction, display EPR spectra which match closely to those from other eukaryotic complexes I, and show patterns characteristic of complex I in SDS/PAGE analysis. Mass spectrometry was used to identify several canonical complex I subunits. Purified P. pastoris complex I has a particularly high specific activity, and incorporating it into liposomes demonstrates that NADH oxidation is coupled to the generation of a protonmotive force. Interestingly, the rate of NADH-induced superoxide production by the Pichia enzymes is more than twice as high as that of the Bos taurus enzyme. Our results both resolve previous disagreement about whether Pichia species encode complex I, furthering understanding of the evolution of complex I within dikarya, and they provide two new, robust and highly active model systems for study of the structure and catalytic mechanism of eukaryotic complexes I.

A radioisotopic technique for analysis of free fatty acid reesterification in human adipose tissue

1985 ◽  
Vol 248 (1) ◽  
pp. E140-E147 ◽  
Author(s):  
R. L. Leibel ◽  
J. Hirsch
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Specific Activity ◽  
High Specific Activity ◽  
Human Adipose Tissue ◽  
Molar Ratio ◽  
Adrenergic Stimulation ◽  
Triglyceride Hydrolysis ◽  
Wide Range ◽  
The Difference

Reesterification rates of free fatty acids (FFA) formed by intracellular triglyceride hydrolysis in small fragments of human adipose tissue were measured. Subcutaneous gluteal adipose tissue, obtained by needle biopsy, was incubated in a buffered albumin medium containing [3H]palmitate and [14C]glucose, each of high specific activity. In triglycerides (TG) and diglycerides (DG) synthesized by the tissue, [14C]glucose is incorporated exclusively into the glyceride-glycerol moiety, and 3H appears solely in the esterified fatty acids. Since rates of TG and DG synthesis can be determined from 14C accumulation rates in these molecules, the total amounts of FFA esterified can also be calculated. The difference between this estimate of total FFA esterification and the moles of [3H]palmitate esterified to these molecules represents the amount of unlabeled FFA from ongoing TG hydrolysis that was reesterified during the incubation. FFA recycling by the reesterification pathway is an important mechanism for the control of the quantity and proportions of FFA and glycerol leaving the human adipocyte. Fasting and beta-adrenergic stimulation reduce the fraction of endogenously released FFA that are reesterified from resting values of 30-40% to 8-21%, thereby increasing the molar ratio of FFA to glycerol leaving the adipocyte. The technique described can be employed to monitor sequential changes in this important metabolic cycle in humans under a wide range of nutritional and clinical circumstances.

Validation of a sensitive direct assay for melatonin for investigation of circadian rhythms in different species

1985 ◽  
Vol 106 (3) ◽  
pp. 387-394 ◽  
Author(s):  
G. E. Webley ◽  
H. Mehl ◽  
K. P. Willey
Keyword(s):  
Specific Activity ◽  
Biological Fluids ◽  
High Specific Activity ◽  
Male Rat ◽  
Rat Serum ◽  
Menstrual Cycles ◽  
High Affinity ◽  
Direct Assay ◽  
Wide Range

ABSTRACT The role of melatonin in animals which do not show marked seasonal changes in reproduction is disputed, in part because of the wide variation in reported concentrations. One reason for this may be the difficulties associated with the measurement of low molar concentrations of melatonin and the presence of a wide variety of potentially cross-reacting substances. The availability of a high affinity antiserum has allowed an assay, with low cross-reactivity and good sensitivity, to be established for the direct measurement of melatonin in a wide range of biological fluids, in particular serum, plasma and follicular fluid from man and rat. The high affinity of the antiserum enabled a tritium label of high specific activity to be used, removing the problems associated with the iodination of a small molecular weight compound. Melatonin concentrations in the assay were evaluated by four different methods: UV absorbance, gas chromatography, comparison of the immunoreactive concentrations of the label with the expected concentration by dilution and by comparison with a previously established assay which uses the same antiserum. Melatonin was measured in serum from twelve healthy women over two 24-h periods; eight women with normal menstrual cycles and four taking the contraceptive pill. Concentrations were found to range from 19·8 to 215 pmol/l during the day in both groups. In women with normal menstrual cycles peak concentrations of 513·2 ± 54·1 (s.e.m.) pmol/l were recorded at 04.00 h, whereas higher concentrations were found in women taking the pill, reaching a peak of 849·12 ± 21·8 (s.e.m.) pmol/l at 04.00 h. Similar melatonin concentrations were measured in the two 24-h periods. In the adult male rat, serum melatonin concentrations varied from 92·66 ± 37·9 (s.e.m.) pmol/l at 12.00 h, rising to 526 ± 55·6 (s.e.m.) pmol/l at 04.00 h. This direct assay is more practical and robust than the assays currently available. The careful validation of assay characteristics allows its widespread use in both clinical studies and the investigation of the role of melatonin in different species. J. Endocr. (1985) 106, 387–394

Effects of Heparin Oligosaccharides with High Affinity for Antithrombin III in Experimental Venous Thrombosis

1982 ◽  
Vol 47 (03) ◽  
pp. 244-248 ◽  
Author(s):  
D P Thomas ◽  
Rosemary E Merton ◽  
T W Barrowcliffe ◽  
L Thunberg ◽  
U Lindahl
Keyword(s):  
Antithrombin Iii ◽  
Specific Activity ◽  
High Specific Activity ◽  
Factor Xa ◽  
Blood Levels ◽  
Thrombin Time ◽  
High Affinity ◽  
Very High

SummaryThe in vitro and in vivo characteristics of two oligosaccharide heparin fragments have been compared to those of unfractionated mucosal heparin. A decasaccharide fragment had essentially no activity by APTT or calcium thrombin time assays in vitro, but possessed very high specific activity by anti-Factor Xa assays. When injected into rabbits at doses of up to 80 ¼g/kg, this fragment was relatively ineffective in impairing stasis thrombosis despite producing high blood levels by anti-Xa assays. A 16-18 monosaccharide fragment had even higher specific activity (almost 2000 iu/mg) by chromogenic substrate anti-Xa assay, with minimal activity by APTT. When injected in vivo, this fragment gave low blood levels by APTT, very high anti-Xa levels, and was more effective in preventing thrombosis than the decasaccharide fragment. However, in comparison with unfractionated heparin, the 16-18 monosaccharide fragment was only partially effective in preventing thrombosis, despite producing much higher blood levels by anti-Xa assays.It is concluded that the high-affinity binding of a heparin fragment to antithrombin III does not by itself impair venous thrombogenesis, and that the anti-Factor Xa activity of heparin is only a partial expression of its therapeutic potential.

Autoprothrombin C Activity from Prothrombin with Snake Venom or Trypsin

1962 ◽  
Vol 08 (03) ◽  
pp. 425-433 ◽  
Author(s):  
Ewa Marciniak ◽  
Edmond R Cole ◽  
Walter H Seegers
Keyword(s):  
Snake Venom ◽  
Thrombolytic Agent ◽  
Sodium Citrate ◽  
Specific Activity ◽  
High Specific Activity ◽  
Citrate Solution ◽  
Clotting Factors ◽  
Activation Products ◽  
Russell’S Viper ◽  
Autoprothrombin C

SummarySuitable conditions were found for the generation of autoprothrombin C from purified prothrombin with the use of Russell’s viper venom or trypsin. DEAE chromatographed prothrombin is structurally altered and has never been found to yield autoprothrombin C and also did not yield it when Russell’s viper venom or trypsin were used. Autoprothrombin C is derived from prothrombin with tissue extract thromboplastin, but not in large amounts with the intrinsic clotting factors. With the latter thrombin and autoprothrombin III are the chief activation products. Autoprothrombin III concentrates were prepared from serum and upon activation with 25% sodium citrate solution or with Russell’s viper venom large amounts of autoprothrombin C were obtained, and this was of high specific activity. Theoretically trypsin is not a thrombolytic agent, but on the contrary should lead to intravascular clotting.

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