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At least 145 records · Page 8Linked to original sources
PubMed2003

Sodium sulphite yields improved DNA of higher stability for PCR detection of Citrus yellow mosaic virus from citrus leaves.

Citrus yellow mosaic virus (CYMV), a non-enveloped bacilliform DNA virus causes a severe mosaic disease in sweet oranges in India. CYMV is weakly immunogenic, thus serodiagnosis is not a preferred method for its detection. As an alternative a rapid and reliable detection protocol by polymerase chain reaction (PCR) was developed. However, high levels of polyphenolics and tannins in citrus leaves generally interfered with obtaining good quality DNA, and thus affected the reliable detection of virus by PCR. Consequently, we evaluated the addition of sodium sulphite to a DNA extraction protocol used previously and compared the two methods with a commercially available plant DNeasy Kit (Qiagen). The addition of sodium sulphite improved the yield, quality and stability of DNA. The CYMV DNA was not only amplified at lower template DNA concentration, but also provided better DNA yields. In addition, the sodium sulphite extracted DNA survived at various temperatures much longer than those extracted without addition of sodium sulphite or with the commercial kit. The amplified product of CYMV DNA was cloned, sequenced and found to have 89% sequence identity with the only other sequenced Indian isolate of CYMV.

Badnavirus↗
PubMed2004

Impact of sand dune stabilization structures on soil and yield of millet in the semi-arid region of NW Nigeria.

The low-rainfall ecologies of the northern fringes of Nigeria are prone to desertification and sand dune activities that are phenomenal and extensive. Stabilization structures put in place by various governmental and non-governmental agencies to check desertification in northwestern Nigeria were evaluated with respect to efficiency, impact on soil development and yield of millet. The study focused on the active and stabilized sand dune formations in NW Nigeria. Various stabilization techniques were identified within Gidan Kaura (the study site) and results were compared with an unstabilized sand dune (control site). Results obtained indicated that the sand dunes within the study area are still active despite the numerous stabilization structures, some of which were established over 15 years ago. Shelterbelts were the most effective techniques in sand dune stabilization and soil development when properly sited across wind direction. Shelterbelts recorded significantly higher levels of pH, organic carbon, total nitrogen, exchangeable bases and micronutrients except for copper, when compared with all other treatments. The least effective of all the structures was mechanical fencing, probably due to the inadequate quantity of plant residues used in its construction. The impact of the various structures on the physical and chemical soil properties was evaluated for surface soils as were the structures on the yield of millet in stabilized dunes and non-dune areas. The results are discussed in depth in this paper.

Carbon↗
PubMed1995

Comparison of four methods to generate immunoreactive fragments of a murine monoclonal antibody OC859 against human ovarian epithelial cancer antigen.

In the present study, four different proteases (pepsin, papain, bromelain and ficin) were screened with a murine monoclonal antibody OC859, in order to verify whether different digestion procedures could improve yield and stability of the F(ab')2 or Fab fragments. The yields of F(ab')2 or Fab fragments from digestion with pepsin, papain, bromelain and ficin were respectively 20.3 +/- 2.0%, 50.5 +/- 5.0%, 74.4 +/- 2.7% and 82.8 +/- 10.2% of the theoretical maximum. Immunoreactivity in a noncompetitive solid-phase radioimmunoassay (SPRIA) of the fragments generated by the four proteases were respectively 10 +/- 5%, 36 +/- 5%, 60 +/- 6% and 75 +/- 6% of the intact OC859 IgG. These results suggested that the fragmentation of OC859 with ficin gave a higher yield of superior immunoreactive fragments.

Animals↗
PubMed2002

Preparation and biological evaluation of 188Re-ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) as a potential agent for bone pain palliation.

This study was undertaken in order to prepare 188Re labelled ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) (EDTMP), and to determine its potential as a therapeutic radiopharmaceutical for the palliation of metastatic bone pain. The effects of pH, incubation methods, and concentrations of stannous chloride, EDTMP, and ammonium perrhenate as a carrier on radiochemical yield and stability were evaluated. Biodistribution studies were performed in male Wistar rats after intravenous injection of 188Re-EDTMP and compared with those of hydroxyethylidene diphosphonate (HEDP). Greater than 95% radiochemical yield of 188Re-EDTMP was obtained under the optimal conditions (0.1 mmol x ml(-1) of EDTMP, 0.5 mg x ml(-1) of stannous chloride, and pH 1.0). Heating the reaction mixture (boiling water for 15 min, and microwave heating for 15 s) and the addition of ammonium perrhenate increased the radiochemical stability (>90% at 3 h, and >80% at 48 h). The biodistribution of 188Re-EDTMP showed high bony uptake and rapid clearance from other organs, and high bone-to-soft tissue ratios, which are similar to 188Re-HEDP. In conclusion, 188Re-EDTMP was prepared with high radiochemical yield and stability, and showed favourable biological characteristics. Microwave heating was a convenient and rapid method for the preparation of 188Re-EDTMP. It is considered that 188Re-EDTMP is a potential therapeutic agent for bone metastasis.

Animals↗
PubMed2005

Use of supplementary genotypes in AMMI analysis.

Improving stability of crop yield in a target production environment is an important breeding objective. It is well known that selection for better stability generally results in lower mean yields and, conversely, that selection for higher mean yields may lead to poorer stability. This paper explores the equivalence between the singular value decomposition used in AMMI analysis and the spectral decomposition used in principal components analysis. This equivalence enables scores of a "supplementary genotype" made up of the highest yield value within each environment to be obtained, and these may serve as the ideal check treatment for selection purposes. These scores are used to (1) display this check in a biplot graph, thereby providing a qualitative comparison with the real genotypes related to their interaction with environments; (2) obtain estimates of the squared distances from the projection of each real genotype to the projection of the "supplementary treatment", thereby allowing conclusions to be made on the yield stability of each real genotype. This procedure was effective in identifying the most stable soybean cultivars in an example shown for illustration.

Agriculture↗
PubMed1991

Calcium-induced associations of the caseins: thermodynamic linkage of calcium binding to colloidal stability of casein micelles.

The caseins occur in milk as colloidal complexes of protein aggregates, calcium, and inorganic phosphate. As determined by electron microscopy, these particles are spherical and have approximately a 650 A radius (casein micelles). In the absence of calcium, the protein aggregates themselves (submicelles) have been shown to result from mainly hydrophobic interactions. The fractional concentration of stable colloidal casein micelles can be obtained in a calcium caseinate solution by centrifugation at 1500 g. Thus, the amount of stable colloid present with varying Ca2+ concentrations can be determined and then analyzed by application of equations derived from Wyman's Thermodynamic Linkage Theory. Ca(2+)-induced colloid stability profiles were obtained experimentally for model micelles consisting of only alpha s1- (a calcium insoluble casein) and the stabilizing protein kappa-casein, eliminating the complications arising from beta- and minor casein forms. Two distinct genetic variants alpha s1-A and B were used. Analysis of alpha s1-A colloid stability profiles yielded a precipitation (salting-out) constant k1, as well as colloid stability (salting-in) parameter k2. No variations of k1 or k2 were found with increasing amounts of kappa-casein. From the variation of the amount of colloidal casein capable of being stabilized vs. amount of added kappa-casein an association constant of 4 L/g could be calculated for the complexation of alpha s1-A and kappa-casein. For the alpha s1-B and kappa-casein micelles, an additional Ca(2+)-dependent colloidal destabilization parameter, k3, was added to the existing k1 and k2 parameters in order to fully describe this more complex system. Furthermore, the value of k3 decreased with increasing concentration of kappa-casein. These results were analyzed with respect to the specific deletion which occurs in alpha s1-casein A in order to determine the sites responsible for these Ca(2+)-induced quaternary structural effects.

Amino Acid Sequence↗
PubMed2001

Pi-donation and stabilizing effects of pnicogens in carbenium and silicenium ions: a theoretical study of [C(XH2)3]+ and [Si(XH2)3]+ (X = N, P, As, Sb, Bi).

Quantum chemical calculations at the MP2 and CCSD(T) levels of theory are reported for cations of the general type [A(XH2)3]+ with A = C, Si and X = N, P, As, Sb, Bi. Population analysis, methyl stabilization energies (MSEs), and structural criteria were used to predict the p(pi)-donor ability of and the pi-stabilization energy exerted by this series of pnicogens. All of the substituents XH2 considered in these studies invariably stabilize the triply substituted carbenium as well as the silicenium ions. The calculated data show that the intrinsic p(pi)-donation of the group 15 atoms follows the order N < P < As < Sb < Bi. However, the trend of the stabilization energies is fully reversed. The intrinsic stabilization energies of the planar carbenium ions decrease monotonically from 161.2 kcal mol(-1) for X = NH2 to 98.0 kcal mol(-1) for X = BiH2. The effective stabilization of the pnicogens in the equilibrium structures, which also includes the energy-demanding pyramidalization of the XH2 substituents, follows the same trend, although the absolute numbers are reduced to 145.6 kcalmol(-1) for X = NH2 and 53.2 kcalmol(-1) for X = BiH2. This seemingly contrasting behavior of increasing p(pi) charge donation and decreasing stabilization has already been found for other substituents. Previous studies have shown that carbenium ions substituted by chalcogens up to the fourth row also stabilize C+ less effectively with respect to heavier substituents. Of the ions investigated in this study, only the silicenium ions that are stabilized by pnicogens from the third to the sixth row of the periodic system yield increased stabilizing energies that follow the corresponding intrinsic p(pi)-donor abilities of the respective substituent.

Journal Article↗
PubMed1981

The intrinsic coagulation-kinin pathway, complement cascades, plasma renin-angiotensin system, and their interrelationships.

Activation of the classical complement pathway is initiated by immune complexes consisting of IgM antibody or IgG subclasses 1, 2, and 3. Binding to Clq leads to activation of C1s and digestion of C4 and C2 to yield a C3 convertase. The alternative complement pathway is initiated by complex polysaccharides as well as immune complexes of the IgA class which interact with Factors B, D, C3, and properdin to yield a stabilized C3 convertase consisting of PC3Bb. Cleavage of C3 and C5 by either pathway yields the C3a and C5a anaphylatoxins which cause histamine release from mast cells and formation of the C5b6789 attack complex causes cell lysis. Both immunologic and nonimmunologic tissue damage can initiate the surface dependent pathways of coagulation, fibrinolysis, and kinin formation. Surface bound Hageman Factor interacts with complexes of prekallikrein and HMW-kininogen as well as Factor XI and HMW-kininogen to form activated Hageman factor, kallikrein, and Factor XIa. Factor XIa continues the coagulation pathway, kallikrein and Factor XIa convert plasminogen to plasmin and kallikrein digests HMW-kininogen to yield bradykinin. The Cl inhibitor, which inactivates Cls is the major plasma inhibitor of activated Hageman factor and kallikrein. In its absence, a potentially fatal form of angioedema is seen. The inactivator of the C3a and C5a anaphylatoxins is identical to carboxypeptidase N, the major plasma inactivator of bradykinin thus demonstrating the common control mechanisms which regulate the complement and kinin-forming pathways.

Blood Coagulation↗
PubMed1996

Effect of non-meat proteins, soy protein isolate and sodium caseinate, on the textural properties of chicken bologna.

Nine formulations were processed into bologna with different ratios of soy protein isolate (SPI):sodium caseinate (SCA), i.e. 1:1, 1:2.5, 1:5, 5:1, 5:2.5, 5:5, 10:1, 10:2.5 and 10:5. The products were evaluated for yields, emulsion stability, physical measurements (shearforce-kgf and folding test) and taste panel evaluation. Formulations with 5:1 and 5:5 SPI:SCA had lower liquid loss resulting in higher yields while the others had poor emulsion stability and high liquid loss. Firmer texture was exhibited by formulations 1:1, 5:1 and 10:1 SPI:SCA but formulation with 1:1 SPI:SCA showed better gelation followed by 1:2.5, 1:5, 5:1, and 5:2.5. The other formulations had poor gelation and binding properties, especially formulation with 10:5 SPI:SCA. Sensory evaluation was carried out using 30 untrained panelists. Attributes evaluated were aroma, texture, chewiness, juiciness, saltiness, chicken taste and overall acceptance. Formulation with 5:1 SPI:SCA was more acceptable for texture, chicken taste and overall acceptance while formulation with 1:1 SPI:SCA was more acceptable for the chewiness, juiciness and saltiness attributes. There was no significant difference (P > 0.05) in aroma attribute, for all formulations.

Adult↗
PubMed1989

A new 99mTc-red blood cell labeling procedure for cardiac blood pool imaging: clinical results.

The first clinical results of a new 99mTc-red blood cell labeling procedure avoiding cell centrifugation are presented. One ml heparinized blood samples were incubated with small amounts of a stannous kit. By titration studies, ideal quantities of sodium hypochlorite for oxidation of extracellular tin and of EDTA as stabilizer of the label were found. The Cl- concentration and pH of the labeled blood were acceptable, and EDTA increased labeling yield and stability determined in vitro by a few percent. The new procedure gave a slightly higher labeling yield than a current technique using centrifugation of cells. Labeling efficiency expressed as cell bound/total activity was 96.6% +/- 1.3% in healthy subjects and 95.5% +/- 2.2% in cardiac patients and remained high for 2 h after reinjection. The biological halflife of labeled cells following the new procedure was 11-12 h rendering it suitable for serial determinations of radionuclide cardiography.

Adult↗
PubMed2004

Development and characterization of a nano-scale contrast agent.

Agents injected parenterally must be less than approximately 8 microm diameter in order to traverse the capillaries in the pulmonary bed, but these agents remain in the vasculature until they are eliminated from the body by a variety of mechanisms. Targeting of cells outside the capillaries requires agent diameters of less than approximately 700 nm to enable escape through the larger-than-usual pores that have been noted in the leaky vasculature of a tumor. The objective of this study was to test the feasibility of creating a surfactant-stabilized nano-bubble with favorable acoustic properties, and identify the key parameters that influence size, yield and stability. Size distribution was characterized using laser light scattering. In vitro acoustic enhancement was assessed by generation of dose and time response curves. We previously developed a successful protocol to generate gas-filled microbubbles (containing perfluorocarbon, sulfur hexafluoride or air) with mean diameter of 1.5 microm, using sonication of carefully selected surfactant mixtures. This presentation describes generation of nano-bubbles with mean diameters ranging from 700 to 450 nm, depending on process variables. In all cases a centrifugation step was employed to separate the nano-sized particles. The in vitro dose response curves gave a maximum of 23-27 dB enhancement compared to buffer in the absence of agent, with the maximum enhancement and presence of shadowing at higher doses being dependent on the fabrication protocol. The effect of sonication time for solutions containing a mixture of the surfactants (Span 60 and Tween 80) was also tested, but was determined not to be an influencing factor. Future studies will involve development of a mathematical model characterizing the mean size as a function of centrifugal force, spin time and initial size distribution. Future work will also include imaging of tumor-bearing mice and measuring imaging potential in vivo in New Zealand white rabbits using power Doppler.

Contrast Media↗
PubMed2006

Zeolite framework stabilized copper complex inspired by the 2-His-1-carboxylate facial triad motif yielding oxidation catalysts.

The stabilization of a mononuclear copper(II) complex with one MIm2Pr ligand [MIm2Pr = 3,3-bis(1-methylimidazol-2-yl)propionate] in the supercages of zeolite Y was attempted, and the resulting materials were tested for their activity in oxidation catalysis. The preparation procedure yielded initially two species (labeled 1 and 2) within the pore system of the zeolite material, which differ in molecular structure and chemical composition as determined by UV/vis, ESR, IR, and XAFS spectroscopy. In species 1, the copper was found to be five-coordinated, with one MIm2Pr ligand in a facial-type NNO coordination toward copper, the other two coordination sites being occupied by oxygen atoms from either the zeolite framework and/or a water molecule. The total charge of this complex is 1+. In species 2, the copper is surrounded by two MIm2Pr ligands, both in a facial-type coordination mode, identical to the homogeneous Cu(MIm2Pr)2 complex. This neutral species 2 is easily washed out of the zeolite, whereas the mononuclear species 1 remains inside the zeolite material upon washing. The spectroscopic characteristics and activity for 3,5-di-tert-butylcatechol and benzyl alcohol oxidation of species 1 compared closely with that of the zeolite-immobilized Cu(histidine) complexes but differed from that of the homogeneous Cu(MIm2Pr)2 complex. It was therefore found that encapsulation in zeolite offers a route to stabilize a 5-fold-coordinated copper complex with novel catalytic properties. This 1:1 Cu(MIm2Pr) complex is not formed in solution.

Biomimetic Materials↗
PubMed1994

Partitioning of plasmid R1. Ten direct repeats flanking the parA promoter constitute a centromere-like partition site parC, that expresses incompatibility.

The parA partitioning system of plasmid R1 consists of three different components: the cis-acting centromere-like parC site, and the two trans-acting proteins ParM and ParR. These three components are contained within a region of 1.6 kb. The parC site is located upstream of the two genes, parM and parR, which are expressed as an operon from the parA promoter. The parC site contains an array of ten 11 base-pair direct repeats, organized in two sets of five repeats flanking the parA core promoter sequences. Deletions and point mutations were introduced in the parA locus, resulting in partially stable and unstable plasmids. An analysis of these parA- plasmids showed that ParM and ParR are transacting. The 160 bp minimal parC region contained sufficient in cis information for efficient trans-complementation. Both proteins were required for maximal stabilization of a parC+ mini-R1 plasmid, although ParR alone, donated either in cis or in trans, yielded partial stabilization. Plasmids that overexpressed ParR caused destabilization of a co-resident parA+ plasmid, whereas overexpression of ParM had no such effect. The parC site exerted incompatibility (incA) at high but not at low copy number. Likewise, the entire parA system exerted incompatibility in a copy number-dependent fashion, and stronger than the incompatibility expressed by parC alone.

Base Sequence↗
PubMed1993

Stabilization of the antigenicity of coxsackie B procapsids by disoxaril.

Disoxaril added to cell cultures infected with coxsackie B virus serotypes 3 or 4 increased the yield and stabilized the antigenicity of the procapsids. In the absence of disoxaril, the procapsids lost their broad antigenicity after a short period of time. Prevention of this loss by disoxaril was observed in radioimmunoassays of IgM in sera from patients infected with various enteroviruses. The procapsids are useful in serological diagnosis of enterovirus infections, and the addition of disoxaril facilitates this technique.

Antibodies, Viral↗
PubMed2004

[Adaptability of sweet corn ears to a frozen process].

The effects of frozen condition on the quality of three sweet corn ears (2038, 2010, 2004) and the pattern (Bonanza), were evaluated. Biometrics characteristics like ear size, ear diameter, row and kernel deep were measured as well as chemical and physical measurement in fresh and frozen states. The corn ears were frozen at -95 degrees C by 7 minutes. The yield and stability of the frozen ears were evaluated at 45 and 90 days of frozen storage (-18 degrees C). The average commercial yield as frozen corn ear for all the hybrids was 54.2%. The industry has a similar value range of 48% to 54%. The ear size average was 21.57 cm, row number was 15, ear diameter 45.54 mm and the kernel corn deep was 8.57 mm. All these measurements were found not different from commercial values found for the industry. All corn samples evaluated showed good stability despites the frozen processing and storage. Hybrid 2038 ranked higher in quality.

Biometry↗
PubMed1996

Large variations of plasma levels during maintenance treatment with depot neuroleptics.

BACKGROUND: Stability of neuroleptic medication has been associated with optimal clinical effect and minimal side-effects. Depot administration is assumed to yield better stability. METHOD: Thirty patients on depot neuroleptic treatment were followed during three years with repeated measurements of plasma level and concurrent ratings of clinical symptoms and side-effects. RESULTS: Of 120 blood samples 35 (29%) measurements were outside +/-2 s.d. measurement error (expected 5%). Perphenazine levels were more variable (46%) than haloperidol (25%) and flupenthixol (12.5%). No relationship was found between side-effect ratings and fluctuations of plasma levels. CONCLUSION: Depot neuroleptic medication does not eliminate a clinically unwanted and sometimes marked variation in plasma level.

Adult↗
PubMed2004

Gas chromatography of trimethylsilyl derivatives of alpha-methoxyalkyl hydroperoxides formed in alkene-O3 reactions.

The synthesis of trimethylsilyl (TMS) hydroperoxide derivatives for gas chromatography (GC) was studied using N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA) for derivatization of cumene hydroperoxide (CMOOH) (alpha,alpha'-dimethylbenzyl hydroperoxide) and alpha-methoxyalkyl hydroperoxides formed by liquid- and gas-phase ozonolysis of a series of terminal alkenes in the presence of methanol (CH3OH). Derivatization efficiencies >90% were achieved over a wide range of solution concentrations. The major compounds identified by GC-mass spectrometry of the derivatized products of alkene-O3 reactions were alpha-methoxyalkyl hydroperoxides, methyl esters, and aldehydes. Yields of alpha-methoxyalkyl hydroperoxides and methyl esters were quantified using effective carbon numbers (ECNs) and used to determine the yields of stabilized Criegee intermediates (SCIs) from gas-phase ozonolysis reactions. Such measurements are important for understanding the atmospheric chemistry of alkene emissions. SCI yields measured for the reactions of 1-octene [CH3(CH2)5CH=CH2], 1-nonene [CH3(CH2)6CH=CH2 ], and 2-methyl-1-octene [CH3(CH2)5C(CH3)=CH2] are consistent with previous measurements or predictions based on literature data. SCI yields measured for the reactions of 1-decene [CH3(CH2)7CH=CH2], 1-dodecene [CH3 (CH2)9CH=CH2], and 1-tetradecene [CH3(CH2)11CH=CH2] are much lower than expected, apparently due to side reactions with low volatility aldehydes that form peroxyhemiacetals, which are not amenable to GC analysis. In general, the results indicate that off-line MSTFA derivatization can be an efficient means for increasing the stability of thermally labile hydroperoxides for identification and quantitation by GC, and offers a new approach for the analysis of these environmentally important compounds.

Alkenes↗
PubMed2004

Improvement in thermal stability and substrate binding of pig kidney D-amino acid oxidase by chemical modification.

Chemical modification was evaluated to stabilize pig kidney D-amino acid oxidase (pkDAAO), which is required for analytical determination of D-amino acids. Optimization of modification conditions was performed to obtain high recovery yield and stability, and chemical modification at 30 degrees C for 12 h with a highly concentrated enzyme solution gave dextran-conjugated pkDAAO with a 70% yield of activity. pkDAAO was stable at less than 55 degrees C at pH 6.0, while the conjugated enzyme was stable even at 70 degrees C. In addition, the conjugated enzyme showed decreased Km values for D-amino acids. Because of these outstanding characteristics, this new material is expected to be available for use as a liquid assay reagent.

Amino Acids↗