Gas chromatographic chemical ionization-mass fragmentometric assay of catecholamines in the brain

A method for gas chromatographic chemical ionization-mass fragmentometric assay of tissue catecholamines is described. Catecholamines were extracted by HClO4, absorbed to aluminum oxide and eluted by acetic acid. Pentafluoropropionic derivatives were made and injected into a gas chromatograph-mass spectrometer equipped with a chemical ionization device. The method was found to be very sensitive and results were reproducible. Epinephrine and norepinephrine could be assayed without interference from each other because of the differences of m/e numbers. Results of dopamine and norepinephrine analyses on human autopsy brain specimens were consistent with those reported in the literature using different methods. Epinephrine in small amounts could be detected in most of the cases analyzed, being highest in amount in the hypothalamus. The results suggest that epinephrine may be acting as a neurotransmitter in certain areas of the human brain.

Adult type neuronal storage disease with neuraminidase deficiency

We describe a patient with adult-onset neuronal storage disease characterized by myoclonus, cerebellar ataxia, convulsive seizures, cherry-red spots, skeletal dysplasia, mild gargoyle features, inguinal hernia, and angiokeratoma. Cytoplasmic inclusions consistent with lysosomal storage disease were demonstrated in neurons of the autonomic nervous system. Accumulation of GM3 and GM2 gangliosides was found in sympathetic ganglia but a catabolic disturbance of these gangliosides was ruled out by normal levels of GM3 ganglioside sialidase and N-acetyl-beta-hexosaminidase A activities. beta-Galactosidase activity was decreased in leukocytes and fibroblasts, but not in serum. GM1 gangliosidosis was ruled out by lipid analyses, and mucopolysaccharidosis by normal excretion of mucopolysaccharide in urine. Sialyl oligosaccharides were increased in urine and alpha-neuraminidase was deficient in fibroblasts. This disorder is considered to be an inherited metabolic disorder of sialyl glycoproteins and oligosaccharides due to deficiency of an alpha-neuraminidase.

Characterization of trimethylsilyl derivatives of cerebrosides by direct inlet-chemical ionization mass spectrometry

Submicrogram quantities of trimethylsilyl derivatives of cerebrosides obtained from the spleen of a patient with Gaucher's disease and from bovine brain were analyzed by direct probe inlet-chemical ionization mass spectrometry, using isobutane as the reagent gas. Quasimolecular ions (QM+, M + 73) and other recognizable fragment ions produced by the successive elimination of trimethylsilanol and sugar residue gave useful information about fatty acid compositions. These ions could also be utilized for qualitative analyses of the molecular species of cerebrosides. Cerebrosides with non-hydroxy and hydroxy fatty acids could be discriminated from each other by comparing the intensities of their quasimolecular ions. Cerebrosides with saturated and monounsaturated fatty acids could also be discrimnated from each other, because the mass number decreased by two mass units in cerebrosides with monounsaturated fatty acids. It was concluded that structural information and molecular species determination could be obtained from small amounts of purified cerebrosides.

Determination of double bond positions of unsaturated fatty acids by a chemical ionization mass spectrometry computer system

After stereospecific oxidation, trimethylsilylated methyl esters of mono- and diunsaturated fatty acids were analyzed by combined gas-liquid chromatography-chemical ionization mass spectrometry. The positions of original double bonds were deduced from the fragment ions produced by the cleavage of the carbon-carbon bond between two trimethylsilyl ethers. These fragment ions were recorded at m/e 187 and 259 in the case of 16:1(n-7), at m/e 187 and 287 in the case of 18:1(n-7), at m/e 215 and 259 in the case of 18:1(n-9), and at m/e 172 and 259 in the case of 18:2(n-6), respectively. The diastereoisomers of monounsaturated fatty acids can be discriminated by comparing the intensities of the fragment ions at m/e 253 and 285 in the case of 16:1 and at m/e 281 and 313 in the case of 18:1. The diastereosiomers of diunsaturated fatty acids may also be distinguished from each other by comparing the intensities of the fragment ions formed by the loss of trimethylsilyl function from the characteristic ions. Mono- and diunsaturated fatty acids in liver may be dominantly in cis- 18:1(n-1) and cis-cis-18:2(n-6) as determined by a mass chromatographic technique.

Biochemical study on myelin in adrenoleukodystrophy

Two myelin fractions, heavy and light, were isolated from white matter of a patient with adrenoleukodystrophy. Morphologically, heavy myelin fraction showed compact lamellar structures, and light myelin fraction consisted of loose lamellar structures and rod-like clear space. Analytical studies demonstrated that the chemical composition of heavy myelin fraction was almost the same as that of normal myelin and that light myelin fraction consisted mainly of cholesterol. Long chain saturated fatty acids, C25:0 and C26:0, were increased and C24:1 was decreased in sphingoglycolipids of heavy myelin fraction of the patient.

Combined gas chromatography-chemical ionization mass spectrometry of sphingolipids. I. Glucosyl sphingosine, ceramides and cerebrosides of the spleen in Gaucher's disease

Trimethylsilylated glucosyl sphingosine, ceramides and glucocerebrosides were analysed by combined gas chromatography (GC)-chemical ionization (CI) mass spectrometry. Isobutane, methane and ammonia were used as reactant gasses for chemical ionization. Essentially the same fragment ions were detected in the spectra with the different reactant gases. Purified glucocerebrosides isolated from the spleen of a patient with Gaucher's disease were clearly separated into their 8 molecular species by gas chromatography. Three other minor components were detected by spectrometry, and these 11 molecular species of glucocerbrosides from the spleen of the patient with Gaucher's disease have been analysed. The ceramides obtained by periodate oxidation and then alkaline reduction of the glucocerebrosides were also separated into 11 molecular species by GC-CI mass spectrometry. Molecular weight could be determined using the major fragment ion of m/e (M+-90) in the spectra of ceramides and cerebrosides. The chemical ionization method is useful for structural analysis and determination of the molecular species of sphingoglycolipids.

Determination of molecular species of phospholipids from thermophilic bacterium PS3 by mass chromatography

The molecular species of phosphatidylethanolamine, phosphatidyglycerol and cardiolipin of thermophilic bacterium PS3 were determined by a new and simple mass chromatographic technique. The fatty acyl groups of these compounds, unlike those of usual phospholipids, were all saturated and were mixtures of even and odd numbered carbon chains; their [M-CnH2n+1-COOCH2]+ and [M-Cn+1H2n+3COO]+ peaks overlapped. Thus, the acetyldiglycerides derived from these phospholipids were subjected to a combination of mass chromatography using chemical ionization with NH3 and treatment of the phospholipids with phospholipase A2 [EC 3.1.1.4]. These three phospholipids had similar patterns of diglycerides. Expressed as R1 : R2, %, they were found to be 14:14,0-1%, 15:14,0-4%, 15:15, 22-23%, 16:15, 16-20%, 17:15, 28-32%, 17:16, 6-9%, 18:15, 7-13%, 17:17, 3-6%, and 18:16, 0-1%. These results should be of significance in connection with the high stability of the biomembranes of this bacterium.

Chemical ionization mass spectrometry of polyunsaturated fatty acids of human serum

Polyunsaturated fatty acids of human serum were analysed by combination gas-liquid chromatography and chemical ionization mass spectrometry, using isobutane as the reagent gas. The method described yielded the molecular ion of long chain unsaturated fatty acids as the base peak; these were weak or unobservable in the corresponding electron impact mass spectra. In the chemical ionization mass spectrometry, the derivatization with trimethylsilyl ether was demonstrated to be useful for the location of the double bonds of unsaturated fatty acids. Applied toteh serum polyunsaturated fatty acids, these methods have given identification of C18:4, C20:4, C20:5, C22:4, C22:5omega-6, C22:5omega-3, and C22:6.

Omega-cyclohexyl fatty acids in acidophilic thermophilic bacteria. Studies on their presence, structure, and biosynthesis using precursors labeled with stable isotopes and radioisotopes

Omega-Cyclohexyl undecanoic acid and omega-cyclohexyl tridecanoic acid were found in 10 strains of acido-thermophilic bacteria isolated from different Japanese hot springs. These unusual fatty acids were found in the esterified form in glyceride type complex lipids and constituted 74 to 93% of the total fatty acids in the bacteria. The fatty acids other than omega-cyclohexyl fatty acids found were 14-methyl hexadecanoic acid (3 to 15%) and 15-methyl hexadecanoic acid (1 to 6%), and trace amounts of straight chain and methyl-branched tetra- and penta-decanoic acids. Biosynthesis of omega-cyclohexyl fatty acids increased with increase in the concentration of glucose in the culture medium. The metabolism of omega-cyclohexyl fatty acids was studied using deuterium-labeled precursors by mass fragmentation analysis. The deuterium of [2-D]glucose was specifically incorporated into position 2 of the cyclohexyl ring of the fatty acids, indicating that the ring was synthesized from the glucose molecule. Radioactivity was efficiently incorporated into the omega-cyclohexyl fatty acids from labeled glucose, shikimate, and cyclohexyl carboxylate. These findings indicate that omega-cyclohexyl fatty acids are synthesized with glucose through shikimic acid and probably cyclohexyl carboxylyl-CoA derivative as the intermediates.