Catherine Fenselau

Quantitation by Gas Chromatography-Chemical Ionization Mass Spectrometry of Cyclophosphamide, Phosphoramide Mustard, and Nornitrogen Mustard in the Plasma and Urine of Patients Receiving Cyclophosphamide Therapy

Unambiguous and sensitive methods based on gas chromatography-chemical ionization mass spectrometry have been developed to quantitate cyclophosphamide and two alkylating and cytotoxic metabolites, phosphoramide mustard and nornitrogen mustard. The levels of these materials have been determined in the plasma and urine of five patients receiving cyclophosphamide, 60 or 75 mg/kg i.v. Peak plasma levels of phosphoramide mustard of 50 to 100 nmoles/ml were found at 3 hr after cyclophosphamide administration. Variable levels of nornitrogen mustard were found in the plasma. This product may be arising in part from the decomposition of other metabolites during sample storage and preparation.

Enzymatic mechanisms of resistance to alkylating agents in tumor cells and normal tissues

The presence in tumor cells and in normal cells of enzymes which metabolize and inactive alkylating agents appears to play a major role in determining the effectiveness of alkylating agents against human tumors and the toxicities of these agents to normal tissues. The enzyme aldehyde dehydrogenase appears to protect bone marrow and the gastrointestinal tract against toxicity from cyclophosphamide and other closely related oxazophosphorine agents. The presence of this enzyme in bone marrow stem cells facilitates the elimination of tumor cells from bone marrow suspensions, with preservation of the ability of the marrow suspension to reconstitute normal hematopoiesis in a patient. A variety of mouse and human tumors has been shown to be resistant to cyclophosphamide on the basis of an elevated aldehyde dehydrogenase content. The clinical significance of this type of resistance is currently being explored. Increased levels of glutathione-S-transferase have been shown to be associated with cellular resistance to a variety of alkylating agents. We have identified and characterized the conjugates of nitrogen mustards with glutathione. The formation of these conjugates is catalyzed by glutathione-S-transferase. The further study and characterization of these specific reactions should contribute to the understanding and quantitation of this type of alkylating agent resistance.

Adrenoleukodystrophy: Evidence that abnormal very long chain fatty acids of brain cholesterol esters are of exogenous origin

A terminal patient with adrenoleukodystrophy (ALD) was given 10 mg by mouth of [3,3,5,5,-2H4]hexacosanoic acid (26:0) daily for 100 days until autopsy. Cholesterol esters were isolated from mildly involved white matter and severely degenerated white matter of autopsied brain, then methanolyzed. Gas chromatograph-mass spectroscopic analysis of the fatty acid methyl esters indicated that the deuterated fatty acid was incorporated into the cholesterol esters of these tissues. The proportion of the labeled 26:0 to nonlabeled 26:0 was highest in the area of mild involvement. This demonstrates that at least some of the abnormal very long chain fatty acids which accumulate in brains of ALD patients are of dietary origin and suggests that nutritional therapy of the disease may be feasible.

Mass Spectral Analysis of Complex Lipids Desorbed Directly from Lyophilized Membranes and Cells

Three desorption ionization techniques--laser desorption, plasma desorption and fast atom bombardment mass spectrometry--have been applied to lyophilized cells, membranes, lysed cells and various extracts. It has been shown that intact polar lipids are selectively desorbed from biological membranes by these methods and that their mass spectra provide fingerprints which reflect the unique biochemical composition of each class of cell or membrane.

Reaction of BCNU (1,3-bis (2-chloroethyl)-1-nitrosourea) with polycytidylic acid. Substitution of the cytosine ring.

BCNU has been reacted with polycytidylic acid and two derivatives of CMP, 3-hydroxyethyl-CMP and 3,N4-ethano-CMP, have been identified in the acid hydrolysate of the polymer. Their formation accounts for some of the reaction of BCNU with nucleic acids, and may be related to the mechanism of action of this compound.

Mass spectrometric study of the distribution of cyclophosphamide in humans

Abstract Cyclophosphamide has been identified in human milk, sweat, saliva, cerebrospinal fluid and synovial fluid after administration to patients by iv infusion. The drug was identified without purification, in organic extracts of the fluids. The mass spectrometric method is described, and some implications of this previously undocumented distribution pattern are discussed.

Is oestrogenic activity present in hops

Abstract During the last 20 yr, several claims have been made for the presence of large quantities of oestrogens in hops and it has been alleged that this hormonal activity appears in beer. The oestrogenic activities reported were very high in comparison with those in other plants. A number of purified hop components, including the essential-oil fraction and the α-and β-bitter acids obtained from hop resins, have now been examined and various organicsolvent extracts of hops grown in the USA and in Europe have been prepared and tested for oestrogenic activity, both directly and following saponification in base. Commercial hop extracts were also tested for oestrogenic activity. Wide ranges of dilutions of all preparations were examined by the uterine-weight assay in the immature female mouse. No oestrogenic activity was detectable in any of these preparations.

Gas Chromatography Mass Spectrometry: A Report on the State of the Art

Instrumental and technical aspects of the combination gas chromatograph mass spectrometer are discussed, with emphasis on the various ways in which the mass spectrometer can serve as a detector for the gas chromatograph. A number of examples of applications are presented, in which the gas chromatograph mass spectrometer is used in its various instrumental modes. Computerized data processing is reviewed, and examples of applications are presented. Most of the examples of applications are taken from pharmacology and toxicology. Special attention is given to stable isotope analysis and to the role of stable isotopes in quantitation by gas chromatography mass spectrometry of samples in the subnanogram range.

Phosphorylation sites in riboflavin-binding protein characterized by fast atom bombardment mass spectrometry

The capability of fast atom bombardment mass spectrometry for characterization of phosphorylation sites in a tryptic peptide from chicken egg yolk riboflavin-binding protein has been evaluated. The quality of information about molecular weight, amino acid sequence, phosphorylation sites, and microheterogeneity is evaluated as a function of the sign of the ions analyzed, the nature of the counter ions associated with the phosphate substituents, sample matrix, and various instrumental parameters. The intact octaphosphorylated 23-residue peptide was found to be susceptible to mass spectral analysis. Information from the negative ion spectrum was used in conjunction with complete sequence information and experiments which showed that all phosphates were attached to serine residues. Phosphorylated and unphosphorylated serine residues were identified and the sample was shown to be homogeneously octaphosphorylated.

Middle molecule mass spectrometry (a review)

Abstract This paper reviews some recent advances in the application of mass spectrometry to the analysis of middle molecules in the mass range of 1000 to 10,000 daltons, and of very polar molecules (organic salts). The quantitative analysis of components of mixtures will be illustrated, carried out by creating a spectrum which consists primarily of molecular ion species whose relative intensities correspond to the relative molar concentrations of the various components.