Showing papers on "Reagent published in 1971"

Immunological reagent and radioimmuno assay

Abstract: A broad new class of reagents permits extremely sensitive and specific assay for, or chemical separation of, a broad range of biological and nonbiological substances. Each reagent consists of a suspension of microscopic carrier material particles, each particle bearing (1) tracer material-fluorescent, radioactive or otherwise - and (2) a coating of biological antibody for the substance whose assay is desired. The latter substance if introduced into the suspension links the particles together in pairs or clumps, which may be sensitively and accurately detected by monitoring the tracer. The carrier is preferably partially hydrolyzed polyacrylamide resin, or in appropriate applications acrylic acid and other derivatives thereof, and other polymers including agar, and the coupling effected by covalent bonding. Other embodiments, including various mechanical forms of carrier, for greater ease of handling and separation, are also described.

Revised assay for serum phenyl phosphatase activity using 4-amino-antipyrine.

Abstract: A modified method for the assay of serum phosphatase activity utilising disodium phenyl phosphate as substrate is described. This is based upon the reaction of free phenol with 4-amino-antipyrine and alkaline potassium ferricyanide. Study of the kinetics of the colour reaction has led to an alteration in the concentration of the reagents used; the colour is formed instantaneously and shows a very slow rate of decay. Sodium arsenate incorporated with the amino-antipyrine reagent effectively abolishes further enzyme activity and prevents the dilution of the colour inherent in earlier methods.

Selective atomic-absorption determination of inorganic mercury and methylmercury in undigested biological samples

Abstract: A simple method for the determination of total mercury in biological samples contaminated with inorganic mercury and methylmercury is described The method is based on the rapid conversion of organomercurials first into inorganic mercury and then into atomic mercury suitable for aspiration through the gas cell of a mercury vapour concentration meter, by a combined tin(II) chloride-cadmium chloride reagent It was found that if 100 mg of tin(II) chloride alone were added instead of the tin(II) chloride-cadmium chloride reagent, only the release of inorganic mercury influenced the peak deflection of the potentiometer, thus permitting the selective determination of inorganic mercury in the presence of methylmercury It was possible first to release inorganic mercury then, after re-acidification of the reaction mixture, methylmercury, by adding the tin(II) chloride-cadmium chloride reagent and sodium hydroxide When total mercury and inorganic mercury were determined separately, the difference between results gave the methylmercury content of the sample

Radioimmunoassay of the f prostaglandins.

Abstract: Antibodies to prostaglandin F2α (PGF2α) were produced in rabbits immunized with a conjugate of PGF2α covalently linked to bovine serum albumin (BSA) by reaction with carbodiimide reagent. A radioimmunoassay was developed using dextran-coated charcoal to separate the free from antibody-bound PGF2α-3H. The sensitivity of the method was about 100 pg. Butanol was used for extraction of plasma and the various classes of prostaglandins were separated on a small silicic acid column. Recovery of PGF2α-3H through the extraction and separation procedures was 75–85%. Equilibration of PGF1α, PGE2, PGE1 PGA2 and PGB1, with antiserum and PGF2α-3H showed a progressive loss of ability to displace the labeled prostaglandin from the antibodies related to the degree of differences in molecular configuration from the hapten used in the immunization. The method should be sufficiently sensitive, precise, and simple to allow its use in the routine estimation of the F prostaglandins from biological samples.

Deficiency of C3 Inactivator in Man

Abstract: C3 inactivator was undetectable in the serum of a previously described patient with increased susceptibility to infection, hypercatabolism of C3 and multiple protein deficiencies. His red cells were positive with specific C3-Coombs reagent but became negative after infusion of normal plasma. Incubation of his red cells with normal serum or with purified C3 inactivator rendered them C3-Coombs negative, whereas incubation in his own serum or buffer did not alter the C3-Coombs positivity. C3 deposited on red cells in vitro by treatment of purified C3 with trypsin or with C1s, C4 and C2 became similarly unreactive with C3-Coombs reagent following incubation with C3 inactivator. C3 inactivator, in addition to its effect on cell-bound C3, acted on fluid phase C3b to yield a product of approximately unchanged molecular size but with an electrophoretic mobility similar to that of C3c. C3 inactivator may play a role in conversion of C3b to C3c in vitro and, perhaps, in vitro .

Chemical Modification of Membranes: II. Permeation paths for sulfhydryl agents

Abstract: The amino-reactive reagent, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS),1 considerably reduces the uptake of the sulfhydryl agent, parachloromercuriphenylsulfonic acid (PCMBS), but does not reduce its effects on cation permeability and on cation transport. These data indicate that PCMBS enters the membrane by at least two channels, one sensitive and the other insensitive to SITS, with only the latter leading to the cation-controlling sulfhydryl groups. Substitution of phosphate or sulfate for chloride results in an inhibition of PCMBS uptake via the SITS-insensitive pathway. These and other data lead to the conclusion that the SITS-sensitive pathway is the predominant one for anion permeation, and the insensitive one for cation permeation. Parachloromercuribenzoate (PCMB), an agent that is more lipid-soluble than PCMBS, penetrates faster but has a smaller effect on cation permeability. Its uptake is less sensitive to SITS. These and other observations suggest that the cation permeation path involves an aqueous channel in the membrane.

The Reactions of Grignard Reagents with Transition Metal Halides: Coupling, Disproportionation, and Exchange with Olefins

Abstract: The reactions of transition metal halides (Mn, Fe, Co, Ni, Pd, Cu, and Ag) with the low-molecular-weight alkyl Grignard reagents in tetrahydrofuran and diethyl ether, especially in the presence of styrene were reinvestigated. An alkyl transition metal species formed in situ by metathesis decomposed to a dialkyl (oxidative dimerization) or to an alkene and an alkane (oxidative disproportionation). Silver(I) and copper(II) were particularly effective in oxidative dimerization of primary alkyl groups. Alkyl groups which contain no β-hydrogen were also coupled by iron, cobalt, nickel, palladium, and copper(I) halides with varying degrees of efficiency. Oxidative disproportionation was generally the more common route to decomposition for alkyl groups which have β-hydrogens. It seemed to proceed directly via a bimolecular interaction of alkylmetals or indirectly by elimination of a hydrido-metal species. If the latter added to an alkene reversibly, exchange was observed between Grignard reagent and alkene. Styr...

Zerovalent platinum chemistry. Part VI. The reactions of bis- and tris-triphenylphosphineplatinum(0) with hydrogen sulphide, hydrogen selenide, sulphur, and related molecules

Abstract: The reactions of Pt(PPh3)n(n= 2 or 3) with H2M, HMPh, and M (M = S or Se) to form adducts have been studied. The reactivity of the products towards soft and hard reagents has been investigated and compared with that of related H2M, HMPh, and M adducts of some RhI and IrI triphenylphosphine complexes. The results agree with the proposed mechanisms of poisoning of metal surfaces by species such as H2M or M.

A simplified alkaline phosphotungstate assay for uric acid in serum.

Abstract: An alkaline phosphotungstate procedure was developed in which the phosphotungstic acid reagent is used both as protein-precipitating and oxidizing reagent. The procedure requires only a 0.2-ml sample and fewer reagents and manipulations than similar procedures, but yields results equivalent to those obtained by Henry’s alkaline phosphotungstate procedure. Recovery, precision, and linearity were good over a wide range of uric acid concentrations. Standardization was easy with use of aqueous albumin standards or of commercial calibration reference sera.

A single-reagent manual method for directly determining urea nitrogen in serum.

Abstract: A direct method is described, in which a single reagent is used without deproteinization, for measuring blood urea nitrogen (BUN) in serum. The reagent is a mixture of diacetylmonoxime, antipyrine (phenazone), and arsenic pentoxide in acid solution. Lipemia, bilirubin to 25 mg/100 ml, hemoglobin to lg/100 ml, and protein to 20g/100 ml do not affect the results. Beer’s law is followed at 460 nm for BUN concentrations as great as 100 mg/100 ml. The direct method compares favorably with a manual urease— Berthelot color method and with the diacetylmonoxime procedure as automated for the Technicon SMA 6/60. The method (CV, 6.7%) can be completed in less than 20 mm. The reagent is stable for at least two months.

Competitive labelling, a method for determining the reactivity of individual groups in proteins. The amino groups of porcine elastase

Abstract: 1. A method is described for determining the ionization constants and reactivities of individual amino groups in proteins. The principle is that in the presence of a trace amount of radioactive label, the various reactive groups in a protein molecule will compete for the label and the amount incorporated into any one group will be determined by its nucleophilicity, pK and micro-environment. The relative amounts of label incorporated into various groups will be proportional to their second-order rate constants and by comparing these rate constants with those expected on the basis of a linear free-energy relationship obtained with a series of standard compounds, the micro-environment can be defined for a particular amino group. 2. The method consists of treating a protein and an internal standard with a limiting amount of radioactive reagent and then with an excess of unlabelled reagent to yield a chemically homogeneous but heterogeneously labelled compound. After appropriate enzymic digestion peptides containing each labelled group are isolated and their rates of reaction, relative to the internal standard, are determined from their specific radioactivities. The entire procedure is repeated at several pH values. 3. When the method was applied to the amino groups of porcine elastase by using tritiated acetic anhydride as the labelling reagent, the N-terminus was found to have pK(a) 9.7 and a much lower than normal reactivity. Lysine-87 and lysine-224 were found to have pK(a) 10.3 and normal reactivities. At pH values greater than 10.5 there are discontinuities in all the titration curves, indicating that the entire molecule is undergoing a structural reorganization.

Diagnostic test slide

Abstract: A test slide for the performance and observation of an immunochemical or diagnostic test on its surface, which surface is insoluble in, impermeable to, non-absorbent to, and wettable by, water, carries on its surface at least one circumscribed test area containing a single solid dried stable spot deposit of an immuno-chemical reagent providing a predetermined amount of an antigen or an antibody, or alternatively, a second solid dried spot of a buffer material, said spot or spots upon being moistened with a liquid and/or the liquid to be tested being reconstituted to the reagent and/or buffer, to form an observable area of reaction mixture.

Determination of enantiomeric purity by an optically active nuclear magnetic resonance shift reagent of wide applicability

Abstract: Addition of the europium complex of 3-heptafluorobutanoyl-(+)-camphor to racemates of alcohols, sulphoxides, an epoxide, and an aldehyde causes separation of n.m.r. signals of the enantioners.

Location of Energy Barriers. IV. Effect of Rotation and Mass on the Dynamics of Reactions A + BC

Abstract: Examination of the effect of the inclusion of a small but significant amount of rotational energy in the reagents, and of a change in reagent masses in a previous study of the effect of barrier location on the dynamics of thermonuclear reaction A + BC yields AB + C. The qualitative generalizations introduced in the previous study are found to remain valid despite the introduction of the variables. Of these generalizations the most important is that reagent translational energy favors reaction on surface I, whereas reagent vibration is the most favorable to reaction on surface II.

Preparation of degradable polymeric material

Abstract: There is disclosed the preparation of a degradable polymeric material by applying a degradation-sensitizing reagent to the surface of a polymeric material and then diffusing the reagent into such surface.

Apparatus for chemical testing

Abstract: A reagent container having a series of tiered compartments containing prepackaged reagents for the chemical evaluation of a test sample. A frangible diaphragm seals each compartment from the succeeding compartment. A sample is introduced into the top compartment. After incubation a breaker punctures the seal of the adjacent compartment, allowing the reagents to mix and react. The procedure is repeated for each reagent filled compartment.