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At least 1,153 records · Page 64Linked to original sources
PubMed1978

A solid phase radiommunoassay on hydrophobic membrane filters: detection of antibodies to gonococcal surface antigens.

A solid phase radioimmunoassay (SPRIA) has been developed for detection of IgG antibodies to gonococcal outer membrane components. Gonococcal antigens were immobilized on a solid support by covalent coupling to CNBr-activated Sepharose in the presence of the detergent Triton X-100. Binding of specific antibody to the Sepharose-antigen complex was detected using radiolabelled Protein A as the antiglobulin. Protein A was labelled by radioacetylation with tritiated acetic anhydride, yielding a product of high specific activity and high stability. No detectable loss of activity was observed over a ten month period. The entire assay was performed on Mitex teflon hydrophobic membrane filters which held the Sepharose beads and aqueous supernatant as a discrete drop of liquid. The supernatants and incubation media were easily and rapidly removed from the beads by suction on a specially designed manifold system. This procedure removed the need for repeated and time-consuming centrifugations. Titres were obtained graphically from double log plots of cpm bound versus antiserum dilution by extrapolation of the straight line to a point corresponding to twice the control level of radioactivity binding. The assay proved to be a very reliable and simple procedure for the detection of IgG antibodies to gonococcal surface antigens.

Antibody Specificity↗
PubMed1986

Freeze-fracture methods: preparation of complementary replicas for evaluating intracellular ice damage in ultrarapidly cooled specimens.

Thin biological specimen sandwiched between conductive metal foils and ultrarapidly frozen in the absence of chemical pretreatments are well suited for ultrastructural studies by the freeze-fracture technique. However, the roughness of the metal surfaces, together with the thinness of the specimen, produce highly irregular surfaces upon fracturing, and thus yield fragile metal replicas. The techniques described here for stabilizing the replicas, initially with an open mesh grid and finally with a Formvar film, provide a means for obtaining a high percentage of intact replicas from which complementary images can be prepared. With the aid of the montages, complementary regions on the replicas can be located at some later time, usually in less than 1 hr. The complementary images obtained are excellent for evaluating the factors which influence the quality and resolution of the replicas--such as heating and plastic deformation--and for describing the preservation of biological structures. Regions within the specimen which display unacceptable ice crystal growth or damage can be easily and confidently identified in complementary images.

Animals↗
PubMedDate not supplied

Analysis of time to stabilization in the treatment of depression: biological and clinical correlates.

The discovery of clinical and biological variables which correlate with the rate of treatment response is an important aim of outcome research. In this report, such items were assessed in a large group of patients with recurrent depression to determine what variables contribute to stabilization during treatment. Relatively few items were strongly related to time to stabilization aside from age, clinical severity of illness, and number of previous episodes. One biological variable, cortisol nadir, was positively related to the time of stabilization. Similar assessments of non-responders did not yield any specific predictors.

Adult↗
PubMed1989

Sister chromatid exchange and chromosome fragility in the nevoid basal cell carcinoma syndrome.

Previous studies of chromosome stability in the nevoid basal cell carcinoma syndrome have yielded inconsistent results and suffered from small sample sizes and less than optimal controls. We investigated chromosome fragility and sister chromatid exchange in 20 affected individuals from five multiplex pedigrees, and 15 first- or second-degree unaffected relatives. The percentage of case and control cells showing breaks or rearrangements was compared using a test of proportions. A similar procedure was used to compare site-specific sister chromatid exchanges in baseline cultures from affected persons and controls. No significant differences were noted for either chromosome fragility or sister chromatid exchange between the two groups. These results suggest that cancer susceptibility in the nevoid basal cell carcinoma syndrome is not caused by or manifested as chromosome instability.

4-Nitroquinoline-1-oxide↗
PubMed1987

Large-scale preparation of a DNA fragment containing the strong promoter A1 of the phage T7.

A procedure has been developed to isolate DNA fragments on a large scale. A DNA fragment of 130 base-pairs containing the strong promoter A1 of the phage T7 was purified to homogeneity in amounts of 10 mg. The procedure includes the rapid purification of gram amounts of plasmid DNA, a new, simple method to separate small DNA fragments from the vector by a phenol/water partitioning system, and a liquid-liquid PEG-dextran partition chromatography for the final purification of the fragment. The fragment was cloned in two vector systems: The vector pDS1, to1+ (1), containing an efficient terminator downstream from the promoter integration site, gives high yields, 3-4 mg plasmid DNA per liter medium. In the plasmid pWH802 (2), which is not specially designed for the amplification of a strong promoter, the integration of the promoter was possible but the yield decreased by a factor of about 50. The stability of the inserts was tested in both systems. Monomeric inserts were stable in both plasmids, multimeric inserts up to a tetramer were only stable in pWH802. Only one orientation of the fragment was found.

Biotechnology↗
PubMed1993

The clinical relevance of an auditory attention task (PAT) in a longitudinal study of chronic schizophrenia, with placebo substitution for chlorpromazine.

A new auditory attention task (PAT) is described. The test comprises four different subtest combinations (diotic/dichotic, slow/fast) each of 5 min duration. Omission and commission errors are combined by an index of errors (IE). The PAT was given fortnightly to 20 chronic schizophrenic inpatients for more than one year. Independent psychiatrists rated the patients according to the Brief Psychiatric Rating Scale and a Global Rating Scale. All measures yielded significant test-retest reliabilities. The patients were stabilized on individualized doses of chlorpromazine (CPZ) and randomized to two groups. Placebo was substituted for CPZ during 10 weeks, according to a double-blind cross-over design. Significant deterioration under placebo was detected by all three methods, but the PAT was the most sensitive to change. The PAT mean score (M IE) was correlated with both rating scales. Unlike the rating scales, it also correctly ordered the twenty patients along a dimension which measured the severity of illness and 'predicted' hospital discharge.

Adult↗
PubMed1994

Preparation of a pure 99mTc-F(ab')2 radioimmunoconjugate by direct labeling methods.

Intact IgG and Fab' can be labeled directly with 99mTc to give quantitative incorporation of radioactivity into the protein. With F(ab')2 the reductive conditions yield a mixture of 99mTc-F(ab')2 and 99mTc-Fab'. We now report a direct labeling method to produce only 99mTc-F(ab')2 in quantitative yield and contaminated with 99mTc-Fab'. The properties, stability and biodistribution of the 99mTc-F(ab')2 have been compared to 99mTc-Fab'. This new technology will allow us to compare technetium direct-labeled IgG, F(ab')2 and Fab' derivatives of the same antibody for radioimmunodetection.

Animals↗
PubMed2006

Preparation and biological studies of 125I-DOTA-TATE.

DOTA-TATE, a somatostatin analog was radiolabeled with (125)I in good yields and high radiochemical purity. The product exhibited good stability in vitro. Pharmacokinetic studies in normal Swiss mice showed rapid blood clearance with low thyroid uptake. Biodistribution studies in murine melanoma showed 3.0+/-1.3% ID/g uptake in tumor at 3h post injection (p.i.), with negligible reduction at 24h p.i. Inhibition studies carried out in vivo using cold DOTA-TATE confirmed the tumor specificity of the product.

Animals↗
PubMed2005

Technetium labeling of dextran incorporating cysteamine as a ligand.

INTRODUCTION: Technetium-99m-labeled dextran is a useful imaging agent for procedures such as angiocardiography and lymphoscintigraphy. To improve the availability of 99mTc-labeled dextran, we designed a cysteamine ligand system for dextran labeling. METHODS: Cysteamine derivatized dextran was synthesized as follows. Dextran was oxidized with sodium periodate, coupled with cysteamine and reduced with sodium borohydride to provide the desired amine ligand. The cysteamine-dextran conjugate was then labeled with reduced 99mTc. Whole-body scintigraphy and biodistribution were examined following injection of the 99mTc-labeled cysteamine-conjugated dextran (99mTc-cysteamine-dextran) in ICR mice. Lymphoscintigraphy was performed after intradermal injection of 99mTc-cysteamine-dextran in SD rats. RESULTS: The cysteamine-derived dextran was easily labeled with reduced 99mTc in greater than 96% yield. 99mTc-cysteamine-dextran has a higher chelation stability against diethylenetriamine pentaacetic acid (DTPA) than the 99mTc-dextran. Axillary lymph nodes were clearly visible after intradermal injection of 99mTc-cysteamine-dextran in rats. CONCLUSION: These results suggest that 99mTc-cysteamine-dextran is available for lymphoscintigraphy. This methodology could expand the usage of 99mTc-labeled dextran, particularly for diagnostic purposes.

Animals↗
PubMed2005

The potential of recycling and reusing municipal solid waste incinerator ash in Taiwan.

By 2004, there were 19 municipal solid waste incinerators (MSWI) with a total yearly treatment capacity of 7.72 million tons in service in Taiwan. All 19 incinerators operated daily to generate about 1.05 million tons of incinerator ash, including bottom ash and stabilized fly ash in 2003, and the average ash yield is 18.67%. The total number of incinerators is expected to increase to 27, serving almost all cities in Taiwan by 2007. The authors have suggested a set of criteria based on the yield of incinerator ash (Phi) to study the ash recycle and reuse potential. The Taiwan Environmental Protection Administration has studied the treatment and reuse of MSWI ashes for many years and collected references on international experience accumulated by developed nations for establishing policies on treatment and reuse of MSWI ashes. These citations were analyzed as the basis for current governmental decision making on policies and factors to be considered for establishing policies on recycle and reuse of MSWI ashes. Feasible applications include utilization of ashes, which after sieving and separation of metal particles, produce granular materials. When granular materials comply with TCLP limitations, they can be utilized as cement additives or road base. The procedures of evaluation have been proposed in the performance criteria to be included in the proposed decision-making process of ash utilization.

Conservation of Natural Resources↗
PubMed2003

ESR detection and dosimetric properties of irradiated naproxen sodium.

In the present work, the electron spin resonance (ESR) dosimetric properties of naproxen sodium (NS) was investigated in the dose range of (2.5-25 kGy). Irradiated NS exhibited a very simple ESR spectrum consisting of a broadened antisymmetric single resonance line not saturating up to 2 mW microwave power at room temperature. The sum of two exponential increasing functions associated with two different radicals of different spectroscopic features and relative weights were found best describing experimental dose-response curve. Radiation induced radicals were observed to be very stable at room temperature but the increase in storage temperature increased very appreciably the decay of the contributing radicals. The results of the simulation calculation based on a model of two radicals showed that two carbon dioxide ionic free radicals (*CO(2))(-) of different orientational and environmental features produced by preferential rupture of carboxyl group from the rest of NS molecules in the crystalline matrix, were, likely at the origin of the experimentally observed ESR spectrum. Features such as good time stability of the signal intensity and relatively high radiation yield (G=0.13) were considered providing NS with potential use as dosimetric material in measuring radiation dose in the range of 2.5-25 kGy by ESR technique.

Dose-Response Relationship, Radiation↗
PubMed2001

Thermodynamic insights into proteins from NMR spin relaxation studies.

NMR spin relaxation measurements of picosecond to nanosecond timescale backbone and sidechain fluctuations of protein molecules, and subsequent entropic interpretation yield interesting, but sometimes counterintuitive, insights into proteins. The stabilities of proteins and protein interactions are achieved through enthalpy-entropy compensation, which is partitioned between the backbone and sidechains depending on the nature of the system.

Animals↗
PubMed2003

An exotype alginate lyase in Sphingomonas sp. A1: overexpression in Escherichia coli, purification, and characterization of alginate lyase IV (A1-IV).

Sphingomonas sp. A1 (strain A1) cells contain three kinds of endotype alginate lyases [A1-I, A1-II, and A1-III], all of which are formed from a common precursor through posttranslational processing. In addition to these lyases, another type of lyase (A1-IV) that acts on oligoalginates exists in the bacterium. A1-IV was overexpressed in Escherichia coli cells through control of its gene under the T7 promoter. The expression level of the enzyme in E. coli cells was 8.6U/L-culture, which was about 270-fold higher than that in strain A1 cells. The enzyme was purified to homogeneity through three steps with an activity yield of 10.9%. The optimal pH and temperature, thermal stability, and mode of action of the purified enzyme were similar to those of the native enzyme from strain A1 cells. A1-IV exolytically degraded oligoalginates, which were produced from alginate through the reaction of A1-I, A1-II, or A1-III, into monosaccharides, indicating that the cooperative actions of these four enzymes cause the complete depolymerization of alginate in strain A1 cells.

Alginates↗
PubMed2003

Synthesis and luminescence of zinc and europium alpha-thiophene carboxylate polymer.

The zinc and europium alpha-thiophene carboxylate polymer with very strong red luminescence was prepared by rheological phase reaction method from zinc acetate, europium oxide and alpha-thiophenecarboxylic acid. Molecular weight, thermal analyses and X-ray diffraction pattern were measured. 1H NMR, 13C NMR, IR, XPS, UV, excitation and emission spectra were studied. The polymer with amorphous structure and 7.565x10(5) g/mol weight-average molecular exhibited excellent solubility in common organic solvents and better thermal stability under 270 degrees C in air. The quantum yield of the polymer in acetone was 0.6 relative to quinoline in 0.05 mol/l H(2)SO(4) solution. The energy of the pi,pi(*) excited state of C(4)H(3)SCO(2)(-) can be transferred to Eu(3+) ion resulting in emission from the 5D(0)-->(7)F(j) of Eu(3+) ion through the polymeric chains. Zn(2+) can effectively enhance the luminescence of Eu(3+) in alpha-thiophenecarboxylate polymer.

Europium↗
PubMed2003

Purification and characterization of two beta-glucosidases from a thermo-tolerant yeast Pichia etchellsii.

The thermo-tolerant yeast Pichia etchellsii produced two cell-wall-bound inducible beta-glucosidases, BGLI (molecular mass 186 kDa) and BGLII (molecular mass 340 kDa), which were purified by a simple, three-step method, comprising ammonium sulfate precipitation, ion-exchange and hydroxyapatite chromatography. The two enzymes exhibited a similar pH and temperature optima, inhibitory effect by glucose and gluconolactone, and stability in the pH range of 3.0-9.0. Placed in family 3 of glycosylhydrolase families, BGLI was more active on salicin, p-nitrophenyl beta-D-glucopyranoside and alkyl beta-D-glucosides whereas BGLII was most active on cellobiose. k(cat) and K(M) values were determined for a number of substrates and, for BGLI, it was established that the deglycosylation step was equally effective on aryl- and alkyl-glucosides while the glycosylation step varied depending on the substrate used. This information was used to synthesize alkyl-glucosides (up to a chain length of C(10)) using dimethyl sulfoxide stabilized single-phase reaction microenvironment. About 12% molar yield of octyl-glucoside was calculated based on a simple spectrophotometric method developed for its estimation. Further, detailed comparison of properties of the enzymes indicated these to be different from the previously cloned beta-glucosidases from this yeast.

Amino Acids↗
PubMedDate not supplied

Preparation and in vivo evaluation of an N-(p-[125I]iodophenethyl)maleimide-antibody conjugate.

Protein sulfhydryl reactive N-(4-[125I]iodophenethyl)maleimide (IPEM, 5) was obtained from N-[4-(tri-n-butylstannyl)phenethyl]maleimide in 59-100% radiochemical yield. Conjugation of 5 to NR-ML-05 Fab, a murine anti-melanoma antibody Fab fragment that had been previously reduced with dithiothreitol (DTT), was effected in an average of 85% yield. Results from in vitro chemical challenges and serum stability studies on the IPEM conjugate of NR-ML-05 Fab (6) indicated a stable covalent attachment of the radioiodine. A biodistribution study of the IPEM conjugate in tumor-bearing athymic nude mice showed lack of significant accumulation of radioiodine in the thyroid and stomach which was an indication of in vivo stability. The observed uptake in tumor was consistent with that obtained for Chloramine-T- or p-iodobenzoate-labeled NR-ML-05 Fab conjugates.

Animals↗
PubMed1994

Marked interspecies variations concerning the interactions of camptothecin with serum albumins: a frequency-domain fluorescence spectroscopic study.

Camptothecin, an anticancer agent reknown for its novel mechanism of action and outstanding murine in vivo activity, has to date displayed only modest therapeutic utility against human cancers. The drug contains an delta-lactone ring moiety which, at pH7.4, hydrolyzes to yield a biologically inactive carboxylate form. Comparison of drug stability in both plasma and purified serum albumin samples revealed that ring opening occurred to a much greater extent in human samples versus those of other species. Multifrequency phase-modulation spectroscopic analyses of the intrinsic fluorescence emissions of the two drug forms revealed a physical explanation for the extensive ring opening observed in the presence of human serum albumin (HSA): the protein exhibited a marked 200-fold binding preference for the carboxylate (K = 1.2 x 10(6) M-1) relative to the lactone (K approximately 5.5 x 10(3) M-1). Serum albumins from other species were found to bind camptothecin carboxylate not nearly as tightly as HSA. Due to the unique capacity of human albumin to bind camptothecin carboxylate, resulting in extensive conversion of the drug to its biologically inactive form, it appears that the success of the agent in eradicating cancer in animal models may be inherently more difficult to duplicate in man.

Animals↗
PubMed1991

Base- and sequence-dependent binding of aristololactam beta-D-glucoside to deoxyribonucleic acid.

The dependence on base-pair composition and sequence specificity of the (aristololactam beta-D-glucoside)-DNA interaction was examined by spectrophotometric, spectrofluorometric, spectropolarimetric, thermal melting, thermodynamic, and viscometric studies. Binding of this alkaloid to various natural and synthetic DNAs was dependent upon the base composition and sequences of DNA. The binding parameters obtained from spectrophotometric analysis, according to an excluded-site model, indicated a relatively high affinity of the alkaloid binding to GC-rich DNA and alternating GC polymer. This affinity was further evidenced by the quenching of fluorescence intensity, decrease in quantum yield, and perturbations in circular dichroic spectrum. The alkaloid stabilized all DNAs against thermal denaturation. The temperature dependence of the binding constants was used to estimate the thermodynamic parameters involved in the complex formation of the alkaloid with various DNAs. The negative enthalpy and entropy change increased with increasing GC content of DNA and also compensated one another to produce a relatively small Gibbs free energy change. Viscometric studies showed that in the strong binding region the increase of contour length of DNA depended strongly on its base composition and sequence of bases, being larger for GC-rich DNA and alternating GC polymer. On the basis of these observations, it is concluded that the alkaloid binds to DNA by a mechanism of intercalation and exhibits considerable specificity toward alternating GC polymer.

Alkaloids↗