Soluble epoxide hydrolase derived lipid mediators are elevated in bronchoalveolar lavage fluid from patients with sarcoidosis: a cross-sectional study.

BACKGROUND: Sarcoidosis is a systemic inflammatory multi-organ disease almost always affecting the lungs. The etiology remains unknown, but the hallmark of sarcoidosis is formation of non-caseating epithelioid cells granulomas in involved organs. In Scandinavia, > 30% of sarcoidosis patients have Löfgren's syndrome (LS), an acute disease onset mostly indicating a favorable prognosis. The impact of dysregulation of lipid mediators, which has been investigated in other inflammatory disorders, is still unknown. METHODS: Using three different liquid chromatography coupled to tandem mass spectrometry targeted platforms (LC-MS/MS), we quantified a broad suite of lipid mediators including eicosanoids, sphingolipids and endocannabinoids in bronchoalveolar lavage (BAL) fluid from pulmonary sarcoidosis patients (n = 41) and healthy controls (n = 16). RESULTS: A total of 47 lipid mediators were consistently detected in BAL fluid of patients and controls. After false discovery rate adjustment, two products of the soluble epoxide hydrolase (sEH) enzyme, 11,12-dihydroxyeicosa-5,8,14-trienoic acid (11,12-DiHETrE, p = 4.4E-5, q = 1.2E-3, median fold change = 6.0) and its regioisomer 14,15-dihydroxyeicosa-5,8,11-trienoic acid (14,15-DiHETrE, p = 3.6E-3, q = 3.2E-2, median fold change = 1.8) increased in patients with sarcoidosis. Additional shifts were observed in sphingolipid metabolism, with a significant increase in palmitic acid-derived sphingomyelin (SM16:0, p = 1.3E-3, q = 1.7E-2, median fold change = 1.3). No associations were found between these 3 lipid mediators and LS, whereas levels of SM 16:0 and 11,12-DiHETrE associated with radiological stage (p < 0.05), and levels of 14,15-DiHETrE were associated with the BAL fluid CD4/CD8 ratio. CONCLUSIONS: These observed shifts in lipid mediators provide new insights into the pathobiology of sarcoidosis and in particular highlight the sEH pathway to be dysregulated in disease.

Anti- Versus Pro-Inflammatory Metabololipidome Upon Cupping Treatment.

BACKGROUND/AIMS: This study aimed to explore the metabololipidome in mice upon cupping treatment. METHODS: A nude mouse model mimicking the cupping treatment in humans was established by administrating four cupping sets on the back skin for 15 minutes. UPLC-MS/ MS was performed to determine the PUFA metabolome in mice skin and blood before and after cupping treatment. The significantly changed lipids were administered in macrophages to assess the production of pro-inflammatory cytokines IL-6 and TNF-α by ELISA. RESULTS: The anti-inflammatory lipids, e.g. PGE1, 5,6-EET, 14,15-EET, 10S,17S-DiHDoHE, 17R-RvD1, RvD5 and 14S-HDoHE were significantly increased while pro-inflammatory lipids, e.g. 12-HETE and TXB2 were deceased in the skin or plasma post cupping treatment. Cupping treatment reversed the LPS-stimulated IL-6 and TNF-α expression in mouse peritoneal exudates. Moreover, 5,6-EET, PGE1 decreased the level of TNF-α, while 5,6-EET, 5,6-DHET downregulated IL-6 production in macrophages. Importantly, 14,15-EET and 14S-HDoHE inhibited both IL-6 and TNF-α induced by lipopolysaccharide (LPS). 17-RvD1, RvD5 and PGE1 significantly reduced the LPS-initiated TNF-α, while TXB2 and 12-HETE further upregulated the LPS-enhanced IL-6 and TNF-α expression in macrophages. CONCLUSION: Our results reveal the identities of anti-inflammatory versus pro-inflammatory metabolipidome and suggest the potential therapeutic mechanism of cupping treatment.

Characterization of free radicals formed from COX-catalyzed DGLA peroxidation.

Like arachidonic acid (AA), dihomo-γ-linolenic acid (DGLA) is a 20-carbon ω-6 polyunsaturated fatty acid and a substrate of cyclooxygenase (COX). Through free radical reactions, COX metabolizes DGLA and AA to form well-known bioactive metabolites, namely, the 1 and 2 series of prostaglandins (PGs1 and PGs2), respectively. Unlike PGs2, which are viewed as proinflammatory, PGs1 possess anti-inflammatory and anticancer activities. However, the mechanisms linking the PGs to their bioactivities are still unclear, and radicals generated in COX-DGLA have not been detected. To better understand PG biology and determine whether different reactions occur in COX-DGLA and COX-AA, we have used LC/ESR/MS with a spin trap, α-(4-pyridyl-1-oxide)-N-tert-butyl nitrone (POBN), to characterize the carbon-centered radicals formed from COX-DGLA in vitro, including cellular peroxidation. A total of five types of DGLA-derived radicals were characterized as POBN adducts: m/z 266, m/z 296, and m/z 550 (same as or similar to COX-AA) and m/z 324 and m/z 354 (exclusively from COX-DGLA). Our results suggest that C-15 oxygenation to form PGGs occurs in both COX-DGLA and COX-AA; however, C-8 oxygenation occurs exclusively in COX-DGLA. This new finding will be further investigated for its association with various bioactivities of PGs, with potential implications for inflammatory diseases.

Fish oil prevents essential fatty acid deficiency and enhances growth: clinical and biochemical implications.

Fish oil, a rich source of omega-3 fatty acids, has never been used as the sole source of lipid in clinical practice for fear of development of essential fatty acid deficiency, as it lacks the believed requisite levels of linoleic acid, an omega-6 fatty acid. The objectives of this study were to establish biochemical standards for fish oil as the sole fat and to test the hypothesis that fish oil contains adequate amounts of omega-6 fatty acids to prevent essential fatty acid deficiency. Forty mice were divided into 2 groups that were either pair fed or allowed to eat ad libitum. In each group, 4 subgroups of 5 mice were fed 1%, 5%, and 10% fish oil diets by weight or a control soybean diet for 9 weeks. Blood was collected at 4 time points, and fatty acid analysis was performed. Food intake and weight status were monitored. All groups but the pair-fed 1% fish oil group gained weight, and the 5% fish oil group showed the highest caloric efficiency in both pair-fed and ad libitum groups. Fatty acid profiles for the 1% fish oil group displayed clear essential fatty acid deficiency, 5% fish oil appeared marginal, and 10% and soybean oil diets were found to prevent essential fatty acid deficiency. Fish oil enhances growth through higher caloric efficiency. We established a total omega-6 fatty acid requirement of between 0.30% and 0.56% of dietary energy, approximately half of the conventionally believed 1% as linoleic acid. This can presumably be attributed to the fact that fish oil contains not only a small amount of linoleic acid, but also arachidonic acid, which has greater efficiency to meet omega-6 fatty acid requirements.

The regulation of arachidonic acid metabolism in human first trimester trophoblast by cyclic AMP.

Human trophoblast cells are known to release a range of arachidonic acid metabolites into culture medium, including cyclo-oxygenase, lipoxygenase and epoxygenase products. In this study we investigated the effects of dibutyryl cyclic AMP (db cAMP) on arachidonic acid metabolism in human first trimester trophoblast cells, and also determined the distribution of metabolites between intracellular and extracellular compartments. db cAMP increased intracellular levels of radioactivity within 2 min, and extracellular levels of radioactivity were increased after 30 min. These changes were reflected in increased levels of arachidonic acid metabolites in both compartments, indicating that arachidonic acid was metabolised. db cAMP increased intracellular levels of 5,6-epoxyeicosatrienoic acid (5,6-EpETrE) within 2 min of addition to cultured cells. No changes were detected after 5-10 min, but substantial changes were found 30 min after the addition of db cAMP. The dihydroxyeicosatrienoic acid (DiHETrE) breakdown products also increased with similar kinetics. In contrast, levels of 14,15-EpETrE increased after 5-10 min.

Vaccenic acid feeding increases tissue levels of conjugated linoleic acid and suppresses development of premalignant lesions in rat mammary gland.

The objective of this report was to determine whether vaccenic acid (t11-18:1) is converted efficiently to conjugated linoleic acid (c9,t11-18:2, CLA) in rats via the delta 9-desaturase reaction and, if so, whether vaccenic acid could substitute for CLA as an anticancer agent. In Study 1, rats were fed 1%, 2%, or 3% vaccenic acid in their diet, and tissue levels of CLA and CLA metabolites were determined in liver and mammary gland. In general, concentrations of CLA and CLA metabolites increased proportionately with an increase in vaccenic acid intake, at least up to the 2% dose level. Beyond this dose, there was clearly a plateauing effect. Thus vaccenic acid concentration increased from an undetectable level in the control to 78.5 nmol/mg lipid in the liver of rats fed a 2% vaccenic acid diet. This was accompanied by an increase in CLA from 2.3 to 33.6 nmol/mg lipid. These changes were also mirrored in the mammary gland, where increases in vaccenic acid (from 27.5 to 163.2 nmol/mg lipid) and CLA (from 17.8 to 108.9 nmol/mg lipid) were similarly observed. Vaccenic acid at 2% produced a CLA concentration in the mammary gland that was historically associated with a positive response in tumor inhibition based on our past experience. This provided the basis for selecting 2% vaccenic acid in Study 2, which was designed to evaluate its efficacy in blocking the development of premalignant lesions in the rat mammary gland. In this experiment, formation of histologically identifiable pathology due to intraductal proliferation of terminal end bud cells of mammary epithelium was used as the end point of analysis at 6 wk after carcinogen administration. Treatment with vaccenic acid reduced the total number of these premalignant lesions by approximately 50%. We hypothesize that the anticancer response to vaccenic acid is likely to be mediated by its endogenous conversion to CLA via delta 9-desaturase.

Ontogenesis of CYP2C-dependent arachidonic acid metabolism in the human liver: relationship with sudden infant death syndrome.

A modification of the human monooxygenase system have been previously associated with the sudden infant death syndrome (SIDS): the hepatic CYP2C content was markedly enhanced and resulted from an activation of CYP2C gene transcription. To determine the possible consequence of the up-regulation of CYP2C in SIDS, we examined the metabolism of arachidonic acid (AA) an endogenous substrate of CYP2C involved in the physiologic regulation of vascular tone. The overall AA metabolism was extremely low during the fetal period and rose after birth to generate 14,15 epoxyeicosatrienoic acid (EET), 11,12 EET and the sum of 5,6 dihydroxyeicosatrienoic acid (diHETE)+omega/omega-1 hydroxy AA. In SIDS, the accumulation of CYP2C proteins was associated with a significant increase in the formation of 14,15 and 11,12 diHETE, which were shown to be supported by individually expressed CYP2C8 and 2C9 and HETE1 (presumably 15 HETE). This increase was markedly inhibited by addition of sulfaphenazole, a selective inhibitor of CYP2C9. So, we propose that the higher CYP2C content in SIDS stimulates the production of EETs and diHETEs and might have severe pathologic consequences in children.

Evidence for age-related differences in the fatty acid composition of human adipose tissue, independent of diet.

OBJECTIVE: To test the null-hypothesis that no age difference in adipose tissue fatty acid composition exists independent of dietary fat intake. DESIGN: A cross-sectional survey of coronary heart disease risk factors, the Scottish Heart Health Study, provided needle biopsy adipose tissue fatty acid data and food frequency-derived dietary data. SETTING: Twenty-two Scottish Districts between 1984 and 1986. SUBJECTS: A total of 10,359 men and women aged 40-59 y were randomly recruited in sex and five-year age bands from GP lists. A sub-set of 2308 men and 2049 women (42%) provided satisfactory adipose tissue and dietary data. MAIN OUTCOME AND MEASURES: Multiple regression analysis (adjusting for dietary fats, body mass index and smoking, with and without menopause status for women) of the relationship between individual fatty acids in adipose tissue and age, and between age and the ratio of linoleic acid (C18:2, n-6) to gamma-linolenic acid (C18:3, n-6) as an indicator of delta-6 desaturase activity. RESULTS: Sex-consistent changes with age occurred for linoleate (adjusted regression slope +/- s.e. for men -0.299 +/- 0.1339 and for women -0.504 +/- 0.1731) and gamma-linolenate (adjusted regression slope +/- s.e. for men -0.141 +/- 0.0341 and for women -0.154 +/- 0.0469) both P < 0.0001. These changes gave rise to a significant increase (P < or = 0.005) in the C18:2, n-6 to C18:3, n-6 ratio with age). Dihomo-gamma-linolenic acid (C20:3, n-6) and docosahexa- plus docosapentaenoic acids (C22:5 + C22:6, n-3) also increased significantly with age (P < or = 0.01). For the latter, the adjusted regression slopes were far greater for women (0.596 +/- 0.0575) than men (0.131 +/- 0.0417). CONCLUSIONS: The results show that ageing does influence adipose tissue fatty acid composition independent of diet. The sex differences may partially be due to inadequate adjustment for changes in sex hormone status in males with ageing. Using the current indicator, a decline in the rate limiting step of beta-6 desaturation appeared to occur with age, and was greater in women than in men. These results may indicate that an increase in dietary gamma-linolenic acid (C18:3, n-6) is necessary with age to offset the relative imbalance between PUFA levels which appears to occur. However, any direct health benefit regarding the common diseases of ageing from such a strategy still remain to be clarified.

Effects of dietary gamma-linolenic acid-rich borage oil combined with marine fish oils on tissue phospholipid fatty acid composition and production of prostaglandins E and F of the 1-, 2- and 3-series in a marine fish deficient in delta5 fatty acyl desaturase.

The effects of gamma-linolenic acid-rich borage oil (BO), in combination with different marine oils, namely an eicosapentaenoic acid (EPA) rich oil (MO) or a DHA-rich oil (TO), on tissue fatty acid composition and prostaglandin production were investigated in turbot, a species which lacks appreciable delta5 fatty acyl desaturase activity. The juvenile turbot grew well on the experimental diets and there were no significant differences in final weights between dietary treatments. Irrespective of the marine oil component, both the BO-containing diets increased tissue phospholipid levels of 18:2n-6 and 18:3n-6, and their respective elongation products, 20:2n-6 and 20:3n-6, compared to fish fed a control diet containing a standard Northern hemisphere fish oil. Both the BO-containing diets increased the production of 1-series prostaglandins (PG), this being observed across all tissues investigated with PGF and especially PGE. The BO/MO diet also reduced 20:4n-6 in tissue phospholipids without affecting 20:5n-3, whereas the BO/TO combination decreased 20:5n-3 but increased 20:4n-6. The production of 2-series and 3-series PGs was also altered by the dietary treatments but the changes were less dependent upon the tissue levels of their respective precursor fatty acids, 20:4n-6 and 20:5n-3. The BO-containing diets had very significant effects on gross fatty acid compositions of the phospholipids including increased proportions of saturated fatty acids and n-6 polyunsaturated fatty acids (PUFA) and decreased proportions of monounsaturated fatty acids and n-3 PUFA. Overall, this study shows that eicosanoid production in turbot tissues can be influenced by dietary fatty acids, not only by changes in the absolute and relative levels of specific eicosanoid precursor PUFA in tissue phospholipids, but also by general effects on membrane composition, structure and function induced by gross fatty acid compositional changes.

Increased mean platelet volume after oestrogen replacement therapy.

The effect of hormone replacement therapy (HRT) on platelet size was examined in 38 post-menopausal women before and at end of a 6 week period of HRT. Subjects were treated with cyclical L-norgestrel 75 mg daily from days 17 to 28 of a 28-day cycle combined with continuous conjugated equine oestrogens 0.625 mg daily. Platelet-rich plasma was obtained to measure platelet indices by Coulter analysis. Plasma measurements of luteinizing hormone, follicle stimulating hormone and 17 beta-oestradiol were measured by immunoassays. Platelet membrane fatty acids were measured by gas-liquid chromatography. A significant reduction in platelet membrane linoleic acid, di-homo-gamma-linoleic acid and arachidonic acid of 8.1%, 14.3% and 17.8%, respectively was noted after 6 weeks of HRT (p < 0.01). There was an increase in the platelet count (not significant) and platelet volume (MPV) (P < 0.05) after 6 weeks of hormone therapy. HRT appears to increase mean platelet volume which may indicate an increase in platelet reactivity. There was no correlation between the changes in mean platelet volume and membrane fatty acid changes in platelets after such therapy.

Profiling of arachidonic acid metabolites in rabbit platelets by radio gas chromatography.

A method for profiling arachidonic acid metabolites by radio gas chromatography (GC) is described. The incubation mixture of rabbit platelets with [14C]arachidonic acid was purified on a Sep-Pak C18 cartridge and derivatized with diazomethane, O-methylhydroxylamine and dimethyl-isopropylsilylimidazole. The recovery of total 14C-radioactivity was 93.1 +/- 7.2%. Loss of radioactivity during derivatization was negligible. Baseline separations for [14C]arachidonic acid and its metabolites were obtained in a single run within 45 min by GC using a synchronized accumulating radioisotope detector (GC/SARD). The recovery of radioactivity from the GC column was virtually 100%. The chemical structures of the metabolites were confirmed by GC/mass spectrometry; peaks of arachidonic acid metabolites were assigned by comparison of the methylene unit values with those of radioactive peaks in GC/SARD analyses. The intra-assay coefficients of variation in GC/SARD analyses were less than 10%. The method was used to map the profile of arachidonic acid metabolites formed by rabbit platelets in the presence of indomethacin, baicalein or glutathione.

Quantitation of hydroperoxy-eicosatetraenoic acids and hydroxy-eicosatetraenoic acids as indicators of lipid peroxidation using gas chromatography-mass spectrometry.

Peroxidation of cellular membrane lipids has been implicated in a wide variety of acute and chronic pathologies. We have developed a method for quantifying lipid peroxidation products using gas chromatography-mass spectrometry (GC-MS) in order to help elucidate the role of lipid peroxidation in such disorders. The method involves analysis of the methyl ester, trimethylsilyl ether derivatives of various hydroxyeicosatetraenoic acids (HETEs). 16-Hydroxy-9,12,14-heneicosatrienoic acid was synthesized for use as an internal standard. The assay involves the following steps: The internal standard is added to the sample and cellular lipids are extracted and trans-esterified. Next, any hydroperoxides are reduced with triphenylphosphine and the samples are subjected to two steps of solid phase extraction. The samples are then hydrogenated and the trimethylsilyl ether derivative of the hydroxyls formed. The derivatized HETEs are analyzed by electron impact GC-MS. 12-HETE, 11-HETE, 9-HETE, and 8-HETE are assayed by monitoring ions at m/z 301, 287, 259, and 271, respectively. Standard curves were constructed for each HETE and were linear over the range 1 to 250 ng; correlation coefficients were typically greater than 0.99. The assay has been applied to the study of autoxidation of lipids in both in vitro and in vivo systems.

Essential fatty acid deficiency in cultured SK-N-SH human neuroblastoma cells.

SK-N-SH neuroblastoma cells grown under standard culture conditions contain significant amounts of Mead acid (20:3 omega 9) in phospholipids, indicating essential fatty acid (EFA) deficiency. The amount of esterified 20:3 omega 9 was augmented by growth in a chemically defined EFA-free medium, whereas its presence could be virtually eliminated by supplementation of the culture medium with either arachidonic (20:4 omega 6; AA), eicosapentaenoic (20:5 omega 3; EPA), or linolenic (18:3 omega 3) acids. Substitution of Mead acid for omega 6 fatty acids, particularly evident in phosphatidylinositol (PI), indicates a compensatory replacement of omega 9 for omega 6 fatty acids during EFA deficiency. Studies evaluating [3H]scopolamine binding to the M3 muscarinic acetylcholine receptors (mAChRs) present in these neurotumor cells as well as effects of carbachol on phosphoinositide turnover and intracellular Ca2+ mobilization, indicate that the biosubstitution of 20:4 omega 6 with 20:3 omega 9 does not detectably impair these measures of signal transduction. Stimulation of mAChRs with carbachol increased the cellular mass of diacylglycerol (DAG) approximately 60%. On the basis of distinctive fatty acid "signatures" of each of the phospholipid classes, it is concluded that the DAG initially released following muscarinic stimulation is derived from phosphoinositide breakdown. After several minutes, however, a significant amount of DAG comes from phosphatidylcholine (PC) as well. In contrast to DAG, the composition of phosphatidate (PA) following receptor stimulation closely resembles that of the phosphoinositides, even at the later time points examined. These results support a selective phosphorylation of DAG arising from the stimulated breakdown of phosphoinositides, favoring the conservation of the 1-stearoyl, 2-arachidonoyl (or 20:3 omega 9) moiety.

Collisionally induced dissociation of epoxyeicosatrienoic acids and epoxyeicosatrienoic acid-phospholipid molecular species.

Four isomers of epoxyeicosatrienoic acid (EET) can be formed by cytochrome P-450 oxidation of arachidonic acid: 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid. The collision-induced dissociation of the [M-H]- anion at m/z 319 from each of these isomers, using negative-ion fast atom bombardment ionization and a triple quadrupole mass spectrometer, resulted in a series of common ions as well as ions characteristic of each isomer. The common ions were m/z 301 [M-H2O]- and 257 [M-(H2O + CO2)]-. Unique ions resulted from cleavages alpha to the epoxide moiety to form either conjugated carbanions or aldehydes. Mechanisms involving charge site transfer are suggested for the origin of these ions. A distonic ion series that may involve a charge-remote fragmentation mechanism was also observed. The epoxyeicosatrienoic acids were also incorporated into cellular phospholipids following incubation of the free acid with murine mast cells in culture. Negative fast atom bombardment mass spectrometry of purified glycerophosphoethanolamine-EET species and glycerophosphocholine-EET species yielded abundant [M-H]- and [M-CH3]- ions, respectively. The collision-induced dissociation of these specific high-mass ions revealed fragment ions characteristic of the epoxyeicosatrienoic acids incorporated (m/z 319, 301, and 257) and the same unique ions as those seen with each isomeric epoxyeicosatrienoic acid. With this direct method of analysis, phospholipids containing the four positional isomers of EET, including the highly labile (5,6-EET), could be identified as unique molecular species in mast cells incubated with EET.

Novel renal arachidonate metabolites.

Cells of the thick ascending limb of the loop of Henle (TALH) metabolize arachidonic acid (AA) via the cytochrome P450 monooxygenase system to biologically active products that are resolved into two peaks, P1 and P2, on reverse-phase HPLC. Each peak contains materials that have characteristic biological activity. P1 contains a material that relaxes blood vessels and is structurally similar to a vasodilator, the 5,6 epoxyeicosatrienoic acid (EET). P2 contains a material that inhibits cardiac Na+-K+-ATPase, the major component of which has been identified as the 11,12 dihydroxyeicosatrienoic acid. In mTALH cells obtained from rabbits made hypertensive by aortic coarctation, there was a selective increase in P1 and P2 formation compared to other renomedullary cells. We have identified AA metabolites in bovine corneal epithelium with biological properties and chemical features similar to those of mTALH cells. 12(R)hydroxyeicosatetraenoic acid (12(R) HETE) a possible derivative of the 11,12-EET, is produced by the cornea and also has been shown to inhibit Na+-K+-ATPase activity. Renal microsomes obtained from spontaneously hypertensive rats (SHRs) also metabolize AA via a cytochrome P450 monooxygenase pathway to three principal biologically active metabolites that are formed in increased amounts during the developmental phase of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

High-dose depot-medroxyprogesterone acetate--effects on the fatty acid composition of serum lecithin and cholesterol ester.

Twenty-one women were treated with high doses of depot-medroxyprogesterone acetate (1000 mg/week im) for 6 months as part of the treatment of endometrial carcinoma. The relative fatty acid composition of serum lecithin and cholesterol ester were analyzed. In previous studies low doses of medroxyprogesterone acetate (MPA), in contrast to progestins of the 19-nor-testosterone series, have been shown not to affect the fatty acid composition of serum lecithin and cholesterol ester. However, the high doses of MPA used in this study increased linoleic acid and decreased arachidonic and di-homogammalinolenic acids in serum lecithin. The ability of a steroid to induce this shift has been ascribed to its androgenicity. MPA is considered to have weak, if any, such properties. The findings of this study emphasize the necessity to delineate effects on metabolism of different doses and administrative routes of any particular steroid.

Measurement of eicosapolyenoic acids in the serum by gas-liquid chromatography-chemical ionization mass spectrometry.

The use of octadeutero eicosatetraenoic acid as an internal standard for the reproducible measurement of serum eicosapolyenoic acids (C20:3, C20:4, and C20:5) by gas-liquid chromatography-chemical ionization mass spectrometry is described. The method has the following advantages. The physicochemical properties of the internal standard and the eicosapolyenoic acids are similar. The acids are easily separated from compounds of similar retention times by means of selected ion monitoring. The measurements can be made more rapidly, (10 min per sample) than with previous techniques.

Biochemical differences between human malignant and benign insulinoma tissues.

Five cases of malignant insulinoma and 2 cases of benign insulinoma were studied lipid-chemically. Tissues were collected by surgical operation or biopsy under peritoneoscopy. The total lipid was extracted from each tissue, and one part of each total lipid was separated into phospholipid, triglyceride and other lipid fractions by a thin-layer chromatography (TLC) on silica gel. The fatty acid composition and fatty acid content of each lipid fraction were measured by a gas-liquid chromatography (GLC). The most remarkable difference between malignant and benign isulinoma tissues was a higher percentage value of eicosatrienoic acid in the phospholipid of malignant insulinoma tissues when compared with that of non-malignant insulinoma tissues; the values mentioned above distributed between 9.82 and 3.32 in 5 malignant cases, but were 2.89 and 2.57 in 2 benign cases. Those changes in the phospholipid fatty acid composition of malignant insulinoma tissues may represent one of the mechanisms of malignant growth in the malignant neoplastic tissue.

Effect of whole body gamma irradiation on fatty acid composition of liver lipids of female rats and radioprotection by cystamine.

Effect of whole body gamma irradiation (1200 R) on the fatty acid composition of liver lipids and its triglycerides (TG), phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) has been studied in female rats. Radioprotective effect of cystamine on radiation-induced alterations in fatty acid composition of above liver lipid fractions has been studied by giving crystamine 15 min before irradiation. Irradiation increased palmitic acid levels in liver total lipids, and PE and decreased in TG. Cystamine prevented these changes. Irradiation increased palmitoleic acid levels in liver total lipids, total phospholipids and PC and these were prevented by prior administration of cystamine. Linoleic acid was decreased in liver total lipids, TG, total phospholipids and increased in PE and PC of irradiated rats. Administration of cystamine before irradiation partially protected these changes. Arachidonic acid was reduced in all liver lipid fractions of irradiated rats and this was only partially protected by cystamine, which itself reduced its levels in the control animals. Irradiation increased the levels of eicosatrienoic acid and these were not prevented by cystamine.