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Biomedical subjects

F E Regnier

Publications and source records attributed to F E Regnier.

At least 127 records · Page 7Linked to original sources
PubMed1983

Separation of synthetic oligonucleotides on columns of microparticulate silica coated with crosslinked polyethylene imine.

A rapid and effective method for separating oligonucleotides using high-performance ion-exchange chromatography is described. Columns were prepared by adsorbing a layer of polyethylene imine on 5-micron-diameter porous silica followed by crosslinking with a multifunctional oxirane. This weak anion-exchange matrix was found to be useful in the separation of mononucleotides and oligonucleosides containing up to 20 residues in either homo- or heteropolymers. Small analytical columns (4.2 X 150 mm) had a capacity ranging from less than a microgram in analytical separations to several milligrams in the preparative mode. The columns have proven to be especially useful in assessing the purity of precursor blocks, monitoring the chemical synthesis of oligonucleotides, and isolating reaction products after the synthesis.

Chemical Phenomena↗
PubMed1983

Mobile phase selection for the high-performance ion-exchange chromatography of proteins.

Proper mobile phase selection significantly improved high-performance ion-exchange fractionations of proteins. The pH and salt content of the eluant affected chromatographic behavior on both strong and weak ion-exchange columns. The retention and resolution of a number of proteins was examined on strong and weak ion-exchange supports with regard to these mobile phase variables. The strong ion-exchange columns were found to be superior for the protein separations performed in this study. The selectivity of both weak and strong ion-exchange columns was pH dependent, however, strong ion-exchange columns were operable over a broader range of pH. Examination of the effect of salts demonstrated that their "displacing activity" could be divided into three categories: weak, intermediate, and strong with regard to the protein mixture utilized. Intermediate salts provided best resolution along with good recoveries. Strong displacing salts were useful for eluting strongly retained proteins. The selection of a mobile phase with respect to protein retention is discussed.

Chromatography, Ion Exchange↗
PubMed1983

High-performance cation-exchange chromatography of proteins.

Approximately one-third of all proteins reported in the literature have a pI sufficiently high to be resolved by cation-exchange chromatography. This paper reports the preparation and use of new high-performance polymeric-bonded-phase cation-exchange columns. Starting from a very stable, covalently bonded polyamide coating on microparticulate silica, simple derivatization produces a versatile cation-exchange material useful for separations traditionally performed on classical carboxymethylated soft gel supports. Column behavior was monitored using chymotrypsinogen, cytochrome c, and lysozyme as standards. The polymeric bonded phase was stable to pH 2.5 and exhibits enhanced selectivity for proteins due to a slight hydrophobic character of the matrix. Several separations of biological interest that demonstrate the utility of these small cation-exchange columns for modern biochemical separations are shown.

Bacitracin↗
PubMed1983

A system for coupled multiple-column separation of proteins.

Purification of proteins is commonly a multiple-step process involving size exclusion, ion exchange, affinity, hydrophobic, and other modes of chromatography. In an effort to circumvent the laborious process of collecting the solutes from each column and reintroducing them onto a second column, a valving system is described that directs the samples eluted from a high-performance liquid chromatographic column through a detector with a high-pressure cell into either a second column or into storage loops of a multiloop value. This multiloop value is referred to as a high-pressure fraction collector. After development of the first column is complete, a second solvent can be directed to the second column or high-pressure fraction collector to elute the solutes back through the detector and onto any other column in the system. The process of eluting a sample from a column through a single detector and directing it to the high-pressure fraction collector or any other column in the system may be repeated a number of times. Such valving systems make it possible to chromatograph a single protein component on two or three columns in a short time.

Autoanalysis↗
PubMed1982

A reciprocating, single-needle hemodialyzer with bidirectional flow of sorbent suspension.

Previous theoretical analysis has indicated that adequate mass transfer is possible in a dialyzer with reciprocating membrane motion provided that the dialysate concentration of uremic substances is kept low. Earlier models have utilized a collection of sorbents (charcoal, urease, and a cation exchanger) constrained next to the dialyzer membranes. We have designed a new dialyzer with a sorbent suspension having free access from a reservoir to the spaces between membrane packages. At a treatment rate of 150 ml/min/m2, the in vitro creatinine clearance is 75 ml/min/m2, which agrees within experimental accuracy with the theoretical prediction. The creatinine clearance, flow resistance, and compliance of the dialyzer are constant during four to six hours of testing. In vivo tests have been performed during urea and creatinine infusion in a normal dog and in a dog with 3/4 nephrectomy. The in vivo creatinine clearance agrees within 10% with the in vitro clearance. Sodium, potassium, calcium, and bicarbonate fluxes are acceptable for patients in renal failure. The new design allows a higher capacity for urea and creatinine, since larger amounts of sorbent may be used.

Absorption↗
PubMed1981

Reversed-phase supports for th resolution of large denatured protein fragments.

Large pore (much greater than 300 A), spherical partical silica stationary phases possessing either C18 or C8 hydrocarbon ligands out-performed small pore (60-100A), irregular shaped silicas for the purification of large denatured peptides. Since columns 5 cm in length appeared to be as effective in separating peptides as columns 5 times longer, it is likely that large peptides absorb to the matrix rather than partition between the stationary and mobile phases.

Chromatography, High Pressure Liquid↗
PubMed1979

Rapid analysis of bilirubin in neonatal serum. I. The binding of bilirubin to albumin.

Evaulation of the severity of jaundice in the neonate may be determined by measuring the reserve binding capacity of serum proteins for free bilirubin. Determination of protein-bound bilirubin has been labor intensive, necessitating multiple runs on gel-permeation chromatography columns or, more recently, enzyme assays or fluorescence quenching analysis. We present a method for quantitation of free bilirubin and of bilirubin-binding capacity of serum by liquid chromatography. A gel-permeation column binds free bilirubin while allowing passage and quantitation of protein-bound bilirubin. Subsequent injection of a desorbing agent releases the adsorbed bilirubin from the column, permitting quantitation of free bilirubin. Bound and free serum bilirubin may be determined directly in less than 15 min using 10 microL of serum. The binding of bilirubin to neonatal serum is seen to be quite different from the binding to adult serum. Ion-exchange chromatography of adult and neonatal serum samples shows that their protein profiles are radically different. This difference probably accounts for the binding characteristics.

Bilirubin↗
PubMed1978

Techniques for detecting enzymes in high-performance liquid chromatography.

Techniques are described for the automated detection of a series of enzymes in a high-performance liquid chromatographic system. Detection was achieved by either a direct or a coupled enzyme assay using photometric detectors. In direct detection the immediate enzymatic product was monitored. Coupled enzyme assays required additional enzyme(s) to convert the product of the primary enzyme reaction into a more easily detectable form. The efficiency of both free and immobilized coupling enzyme(s) was evaluated. The detector sensitivity could be increased three-fold by increasing the reaction temperature. This system is particularly suitable for isoenzyme profiling in biological materials.

Animals↗