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Biomedical subjects

B Zak

Publications and source records attributed to B Zak.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

Review of calcium methodologies.

A review of calcium methodologies for serum has been described. The analytical systems developed over the past century have been classified as to type beginning with gravimetry and extending to isotope dilution-mass spectrometry by covering all of the commonly used technics which have evolved during that period. Screening and referee procedures are discussed along with comparative sensitivities encountered between atomic absorption spectrophotometry and molecular absorption spectrophotometry. A procedure involving a simple direct reaction for serum calcium using cresolphthalein complexone is recommended in which high blanks are minimized by repressing the ionization of the color reagent on lowering the dielectric constant characteristics of the mixture with dimethylsulfoxide. Reaction characteristics, errors which can be encountered, normal ranges and an interpretative resume are included in its discussion.

Blood Chemical Analysis↗
PubMedDate not supplied

Review of phosphate methodologies.

A description of the extensive literature on the methodologies for the determination of serum phosphate has been reviewed. The evolution of the various phases of the analytical techniques developed in the last century leading to the simplified, sensitive and accurate procedures of the present have been presented in some detail. A procedure involving a simple direct reaction for the determination of inorganic phosphate in serum using ascorbic acid as a reducing agent and a citrate-arsenite mixture as a stabilizing-sensitizing reagent, all in a semi-aqueous medium containing dimethysulfoxide and the detergent Teepol 610 is recommended. Jaundice and mild hemolysis are noninterferencts and turbidity from severe lipemia is easily overcome by reversing the sequence in which reagents are added because citrate binds molybdate in preference to phosphate. Thus, the serum blank and the reacted serum are identical in makeup thereby yielding an idealized correction for irrelevant absorption. Reaction characteristics and potential errors are included in the discussion of the procedure.

Chemical Phenomena↗
PubMedDate not supplied

Interpretation of cerebrospinal fluid proteins by gel electrophoresis.

The use of polyacrylamide gel electrophoresis (PAGE) for the separation of proteins in cerebrospinal fluid (CSF) results in greater definition than does a "routine" method such as cellulose acetate electrophoresis. Unconcentrated CSF is easily separated into as many as 18 bands by the use of PAGE. By means of a modified PAGE method described in this paper, unconcentrated and untreated CSF is quickly and conveniently analyzed for protein constituents. This modification involves a continuous buffer environment, a pore-size concentration gradient and CSF in amounts of 0.1 to 0.4 ml. Sucrose addition is not necessary in this procedure. Whereas most central nervous system (CNS) disease states do not yield consistently distinctive protein patterns, some diseases, such as vascular disease, infectious meningitis and some metastatic tumors, yield significantly altered patterns. It is suggested that the chief value of CSF protein electrophoresis at the present time is to follow the course of a CNS disease.

Buffers↗
PubMedDate not supplied

Determination of liver microsomal glucose-6-phosphatase.

A procedure for the determination of liver microsomal glucose-6-phosphatase is described. Homogenization and ultracentrifrigation were used to prepare a precipitate whose character was defined by monitoring the desire enzyme activity which serves as a marker. Activity of the enzyme was determined by means of a sensitive colorimetric reaction for the product, inorganic phosphate. Non-enzymatic hydrolysis problems with the substrate are minimized in this procedure by the masking action of citrate. The final heteropoly blue color appears to be considerably sensitized by interaction of phosphomolybdous ion with arsenite. The stability of the relatively labile enzyme was ensured by chelating any metals present with ethylene diamine tetraacetic acid. The overall results obtained by the procedure appear to be useful as an aid in the diagnosis of Type I glycogenosis, a glycogen storage disease called Von Gierke's disease.

Colorimetry↗
PubMedDate not supplied

Enzyme reagents for measurement of phospholipids of amniotic fluid.

Enzymic procedures have been developed for the specific determination of three phospholipids in an effort to make the estimation of the phospholipids of amniotic fluid more sound analytically. Apart from the actual determination of these analytes (lecithin, sphingomyelin, and phosphatidylglycerol), these enzymic procedures facilitate the evaluation of a number of the basic premises and procedural steps involved with the traditional procedures for the evaluation of fetal lung maturity. To this end, the changes are reported in sphingomyelin concentrations with gestational age. Although lacking in sufficient clinical data to assign "cut-off" values as yet, the enzymic procedures seem to correlate well with the existing procedures and are analytically accurate and precise.

Amniotic Fluid↗