Search Results - (Author, Cooperation:M. R. Pillai)

2013-03-08

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Antigens, CD95/metabolism ; Cell Differentiation/*genetics ; Cells, Cultured ; DNA/genetics/metabolism ; Forkhead Transcription Factors/metabolism ; Gene Knockdown Techniques ; Gene Regulatory Networks/*genetics ; Genome/genetics ; Interferon-gamma/biosynthesis ; Interleukin-2/genetics ; Mice ; Mice, Inbred C57BL ; Nanowires ; Neoplasm Proteins/metabolism ; Nuclear Proteins/metabolism ; RNA, Messenger/genetics/metabolism ; Reproducibility of Results ; Silicon ; Th17 Cells/*cytology/immunology/*metabolism ; Time Factors ; Trans-Activators/metabolism ; Transcription Factors/metabolism ; Transcription, Genetic/genetics

1089-7550

AIP Digital Archive

Physics

X-ray diffraction θ–2θ scans and kinematical simulations were used to study the composition modulation in coherently strained ten period InxGa1−xAs/GaAs superlattices grown by molecular beam epitaxy (MBE). Superlattice periods (Λ) were 34.5, 55.0, and 92.0 Å, each with nominally 10-Å-thick In0.5Ga0.5As layers. Simulations using exponential In composition modulations, as expected due to In segregation during MBE growth, produced the best fits to the experimental data. The measured 1/e segregation lengths ranged from 11 to 16 Å. Since this distance was larger than the InGaAs layer thickness, the maximum In concentration reached in the samples was only x(approximate)0.20–0.25. For the Λ=34.5 Å sample, since the GaAs layer was also thin, the composition modulation varied with each period of the superlattice. The simulation also showed layer thickness fluctuations which varied from 1.0 to 2.0 Å for the InGaAs layers and 2.0–3.0 Å for the GaAs layers. © 1998 American Institute of Physics.

Electronic Resource

1572-8854

Springer Online Journal Archives 1860-2000

Geosciences

Physics

Abstract Palladium(II) complexes of an imine-thiophene ligand N,N′ bis(1-methylenethiophene)-1,3-diaminopropane and an amine-phenol ligand N,N′-bis(2-hydroxybenzyl)1,3-diamino-2,2-dimethylpropane were synthesized by reacting K2PdCl4 with alcoholic solutions of the ligands. X-ray structures of the complexes were determined using data from a CAD-4 Nonius diffractometer (MoKα radiation). The structures were solved by conventional methods resulting inR factors of 0.044 and 0.061 using 1841 and 2241 independent reflections, respectively. Crystal data: Complex I, orthorhombic, space groupPbca,a=11.323(2),b=14.819(2),c=23.873(3)Å,V=4006(1)Å3,Z=8. Complex II: Space groupP21/c,a=9.169(2),b=31.920(4),c=8.902(6),β=90.38(2)°,V=2605(1)Å3.Z=4. Both complexes showed coordination of the ligands through the nitrogens only while the sulphur and the oxygen atoms were uncoordinated. Square planar coordination is completed bycis chloro ligands.

Electronic Resource

1572-8854

Springer Online Journal Archives 1860-2000

Geosciences

Physics

Abstract A palladium(II) complex of an amine-phenol ligand N,N′-bis(2-hydroxybenzyl)1,4-diaminobutane has been synthesized and characterized by NMR, IR, and X-ray diffraction studies. Diffraction data were collected with a Nonius CAD-4 diffractometer with θ-2θ scan and MoKα radiation. The structure was solved by conventional methods resulting in anR factor of 0.022 for 1058 independent reflections. The X-ray structure shows a discrete mononuclear square planar complex in which the Pd is coordinated to the two nitrogens and two oxygens of the ligand. The complex is neutral with the Pd(II) charge balanced by deprotonation of both phenolic oxygens. Crystal data: Space group Pna21,a+8.223 Å,b+22.477 Å,c+9.190 Å;V+1698.8 Å3;Z+4.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract We describe a radioimmunoassay procedure for human somatotropin using second antibody — polyethylene glycol (PEG) combination for the separation of antibody bound and free antigen. The assay is done by a single incubation of 18 hours or with one hour pre-incubation and 3 hours post-incubation at room temperature (25 °C) and uses 0.1 mℓ of serum sample. The assay covers a range of 0–40 μg/ℓ and has a sensitivity of 0.6 μg/ℓ of somatotropin. The assay is validated by inter-assay and intra-assay variations, recovery and parallelism tests.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract A single reagent radioimmunoassay for thyroxine in blood samples absorbed on filter paper for the mass screening of neonatal hypothyroidism is described. Blood samples were collected by pricking the heel of newborn babies (3 days old) and pressing Whatman 3 filter paper against the wound. 6 mm diameter blood spots were punched out at the time of assay and incubated with 0.4 ml of a preincubated antigen-antibody complex for six hours at 37 °C. 1 ml of 22% polyethylene glycol is used for the precipitation of antigen-antibody complex. The assay has a sensitivity of 2.2 ng/ml. 500 samples collected from newborns were analyzed in the assay and gave a mean of 117.6±31.9 ng/ml.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract We discribe the development of a simplified radioimmunoassay for triiodothyronine (T3) using pre-incubated labelled T3 and antibody. The assay is carried out by adding 50 μl of standard or sample to 0.4 ml of pre-incubated reagent dispensed in assay tubes. The reaction is allowed to proceed for about four hours and the antigen-antibody complex precipitated by the addition of 1 cm3 of 22% polyethylene glycol solution. Due to the high dissociation constant of T3-antibody complex at 37° C (2.83·10−4 S−1), the labelled antigen-antibody complex dissociates and thereby the unlabelled antigen binds with the antibody. With a four hour incubation the sensitivity of this assay is comparable to an assay done by the equilibrium method using the same antibody. Sixty serum samples were analyzed using this method and compared with the equilibrium assay (Y=0.94x+0.046 ng/cm3, r=0.98).

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract Preparation and purification of radioiodinated progesterone derivatives for the development of a radioimmunoassay of progesterone is described. We have standardized two procedures for preparing radioiodinated progesterone conjugate. In the first procedure125I labeled histamine was conjugated to progesterone 11α hemisuccinate by the mixed anhydride method. In the secod procedure, tyrosyl methyl ester was conjugated to progesterone 11α hemisuccinate and iodination of the conjugate was carried out. Purification of the iodinated products was carried out by solvent extraction and thin layer chromatography techniques. The radiochemical purity of the tracers prepared by both methods were more than 95%. Labeled progesterone derivatives prepared were used for developing a radioimmunoassay procedure. The non-specific binding of the tracer was about 2–3%, while up to 80% binding could be obtained in the presence of excess antibody. The radioiodinated tracer could be used up to four months in the assay.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract Radioiodinated insulin and thyroid stimulating hormones were prepared using 1,3,4,6-tetrachloro-3α, 6α-diphenylglycouril (Iodogen). Conditions of iodination like concentration of iodogen, reaction time, etc., were optimized to get maximum yield. Stability studies of iodogen coated tubes were carried out over a period of time. The dependence of iodination yield on varying amounts of activity and protein concentration were investigated. Iodination yield over a range of pH was also studied. The radiolabelled hormones prepared by this method were used in radioimmunoassay and were compared with tracers prepared by the Chloramine-T method.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract A solid phase radioimmunoassay for triiodothyronine (T3) has been developed using antibody-immobilized serum albumin microspheres. Antibody albumin microspheres were prepared using a “spinning disc aerosol generator”. The low density of the antibody-albumin microspheres gives greater mobility for the particles there by ensuring better kinetics to the antigen-antibody reaction. The assay has a single incubation of one hour at 37° C and the separation of the antigen-antibody complex is accomplished by centrifugation. The sensitivity of this assay is 0.3 ng/cm3 and has a range of 0.3–4 ng/cm3.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract A simple and reliable technique for the simultaneous estimation of serum triiodothyronine (T3) and thyroxine (T4) is discussed. T3 assay was done by the solid phase technique using antibody coated Eppendorf pipette tips. T4 assay was done by the polyethylene glycol separation system. The assay used 50 μl of serum sample. Inter-assay and intra-assay coefficient of variation are less than 12% throughout the assay range, for both assays.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract The paper describes a solid-phase radioimmunoassay for triiodothyronine (T3) using antibody coupled to carboxymethylcellulose powder. The free carboxylic acid groups of cellulose are covalently coupled to the amino groups of the antibody using 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride. Immobilized antibody thus prepared was used in a solid-phase radioimmunoassay of T3. The assay has a sensitivity of 0.18 μg/l, and a range of 0.18–4 μg/l. Satisfactory correlation was obtained when this assay was compared with a T3 assay based on dextran coated charcoal separation system (Y=0.95X+0.15 μg/L; r=0.98).

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract A direct radioimmunoassay for the measurement of progesterone in human serum is described. Progesterone 11α-hemisuccinate was conjugated to tyrosine methyl ester (TME) by the mix anhydride method and then iodinated using chloramine-T. The radiochemical purity of different batches of125I-progesterone was greater than 95% and showed 70–75% binding with excess antibody. Progesterone 11α-hemisuccinate was coupled with BSA and injected to rabits. Antisera collected after three booster injections and having aK value of 1·1091/M was selected for the assay. Significant reduction in binding with antibody was seen when hormone free serum was used in the assay system. Various blocking agents were tried to reduce the serum effects and none of them were found satisfactory. From a series of optimization experiments, an assay was developed without the use of blocking agents. This assay used a much higher concentration of antibody along with lower amount of serum sample (50 μl). The optimized assay has a sensitivity of 0.5 nj/ml and a working range of 0.5 to 100 ng/ml. Serum samples were analyzed analysis showed good correlation between the results obtained from the present system and the DPC kit. (Y=0.93X+0.5,r=0.93, forn=25).

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract The standardisation of a direct radioimmunoassay for progesterone using an125I labeled progesterone prepared by iodinating the tyrosine methyl ester (TME) conjugated to a progesterone hemiphthalate derivative and an antibody prepared using progesterone linked to bovine serum albumin through 11α hemisuccinate derivative is described. The hemiphthalate derivative of progesterone was prepared by reacting 11α-hydroxy progesterone with phthalic anhydride which was then conjugated to TME by using isobutyl chloroformate. The conjugate was iodinated with125I using chloramine-T as oxidising agent and purified by thin layer chromatography. Radiochemical purity of the tracer was 〉95% in all batches. The tracer gave 70–75% binding with excess antibody. Assays were optimised with 8-anilino-1-naphthalene sulphonic acid (ANS) and sodium salicylate as blocking agents to release the progesterone from binding proteins. The assay optimised with sodium salicylate as blocking agent has a sensitivity of 0.25 ng/ml and a working range of 0.25–50 ng/ml, whereas the assay with ANS has a sensitivity of 0.75 ng/ml and a working range of 0.75–100 ng/ml. Serum samples were analysed and compared with the values obtained with a homologous bridge assay.

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract Cerebral amino acid metabolism is known to be associated with various psychosomatic disorders. 3-(123I)iodo-L-alpha methyl tyrosine (123I-L-AMT) is an alternative to the PET radiopharmaceutical, 11C- thymidine, for brain SPECT studies. Radioiodination of L-alphamethyl tyrosine using chloramine T as well as iodogen has been standardized using 125I as the first step towards the development of the SPECT imaging agent 123I-L-AMT. Purification of the iodinated product was carried out over Sephadex LH-20 column. A quick and easy purification method using Sep-pak column also has been standardized. Quality control of the 125I-L-AMT was carried out by estimating the radiochemical purity and stability of the product. Biodistribution studies of the product were carried out in mice. Time dependent pharmacokinetic studies and activity distribution pattern in the different parts of the brain were also carried out.

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