Recognition of Cervical Neoplasia by the Estimation of a Free-Radical Reaction Product (Octadeca-9,H-Dienoic Acid) In Exfoliated Cells

The molar ratio between a diene-conjugated linoleic-acid isomer (18:2(9, 11)) and the parent linoleic acid (18:2(9, 12)), both esterified as phospholipids, was significantly different in exfoliated cells from normal cervices and from cervices with colposcopic and cytological evidence of precancer. The measurement may provide a simple and perhaps improved alternative to cytological screening.     

Mastopathic fibroadenoma of the breast: a pitfall of aspiration cytology

OBJECTIVE: To assess the correlation between cytological diagnoses and histological subtypes of fibroadenoma (FA) and to clarify the cytological features of a specific group of FA displaying variable features similar to fibrocystic disease (mastopathic type, MFA), and to evaluate the significance of this subtype in cytological diagnosis. METHODS: A review of 141 cases of histologically proven FA was performed. We re-classified them into four subtypes according to Kinoshita's criteria [Jpn J Breast Cancer6 (1991) 377] and further selected 92 cases for which both fine needle aspiration (FNA) smears and histological specimens were available. Among them, 18 cases of MFA and their cytological smears were selected for the present study. RESULTS: There was significant correlation between MFA and cytological diagnosis of 'indeterminate' or 'suspicious for malignancy' (P < 0.01). Although no false-positive diagnosis was experienced in our series, 56% of the MFAs (10/18) had cytological diagnoses of indeterminate or were included in the category 'suspicious for malignancy'. Smears from MFA revealed high cellularity (9/18 smears had more than 10 epithelial clusters each composed of more than 50 cells), presence of cellular discohesiveness (13/18, 72.2%), but only mild nuclear atypia (5/18, 27.8%). Anisonucleosis was present in fewer than half the cases and no apparent condensed chromatin was identified. CONCLUSION: We highlight the significance of subclassification of MFA in aspiration cytology of breast. MFA had a significantly higher chance of falling into the 'suspicious for malignancy' or 'indeterminate' diagnostic category in aspiration cytology. It might be a diagnostic challenge for cytopathologist to identify this subtype of FA in FNA smears.     

葱属植物物种生物学研究 Ⅰ.葱属6种材料的核型研究

分析了葱属(Allium L.)5个种6个居群的细胞学特征。这些种是太白韭(A.prattii C.H.Wright apud Forb.et Hemsl.),该种包括两个居群(Ⅰ、Ⅱ)。居群Ⅰ:K(2n)=2x=16=9m+1m(SAT)+4sm+2st,居群Ⅱ:K(2n)=2x=16=10m+5sm+1sm(SAT);天蒜(A.paepalanthoides Airy-Shaw):K(2n)=2x=16=14m+2sm+3B;多叶韭(A.Plurifoliatum Rendle):K(2n)=2x=16=14m+2sm+1B;合被韭(A.tubiflorum Rendle):K(2n)=2x=16=12m+2m(SAT)+2sm;峨眉韭(A.omeiense Z.Y.Zhu):K(2n)=2x=22=2m+18sm+2T(SAT)。所研究的6批材料均为二倍体,除合被韭的核型为“1A”型,蛾眉韭的核型为“3A”型外,其余4批材料的核型均为“2A”型。其中峨眉韭和多叶韭的染色体数目为首次报道,天蒜和多叶韭的细胞中首次发现B染色体,并对其相互关系进行了探讨。     

Influence of breed and age on morphometry and depth of inseminating catheter penetration in the ewe cervix: a postmortem study

A detailed examination of the cervical canal in the ewe was carried out. This analysis could be used to design new catheters for artificial insemination (AI) to achieve deeper cervical penetration and therefore better fertility results. Three hundred and sixty-five cervices from four sheep breeds (Churra, Assaf, Merino, Castellana) obtained postmortem were used. Cervix morphometry and depth of cervical penetration using two types of catheters were determined. A conventional straight catheter for ovine artificial insemination (IMV), and a bent catheter, ending in a stainless steel needle, 9 cm in length and with an 8 mm tip bent 45 degrees , were used. The results showed that the morphometry of the cervix depends on breed and age of the ewe. The cervices of Churra breed were shorter and narrower, and had a higher number of folds than those of other breeds. Postmortem cervical penetration was deeper when the cervices were longer and wider, and with fewer folds (Merino and Castellana breeds). In ageing ewes, the cervix tended to become longer and wider, with loose folds. This decreased structural complexity and significantly improved cervical penetration. The bent catheter allowed significantly greater cervical penetration than the straight IMV one.     

Chromosome Numbers in Leonurus japonicus Houtt. (Labiatae)

Leonurus japonicus Houtt. [L. heterophyllus Sweet, L. artemisia (Lour.) S. Y. Hu] is one of the most important traditional Chinese medicines used as a remedy for gynaecological disease since ancient times. A cytological investigation on the species was carried out and the materials for chromosomal examination were collected from 26 localities in 20 provinoes and autonomous regions of this country. The number of chromosomes in root tip cell of the species was found to be 20 on the whole (Tab. 1:1), agreeing with those reported by Ma and al.^[2] and probably by Chuang and al.^[3] as well. The genus Leonurus L. is variable in its chromosomes with an aneuploidy of x=9, 10 and 12. The present authors would propose that the primitive basic number of chromosome in the genus is 9, and thus both 10 and 12 are derived, for: (1) among the 9 species (including 1 subspecies) heretofore cytologically examined, x=9 occurring in 66.7%, x=10 occurring in 22.2%, while x=12 occurring only in 11.1%; (2) in generaclosely related to the genus under consideration, such as Panzeria, Galeobdolon and Lamium x=9 being the sole basic number. But L. japonicus exhibits a mixoploidy of 2n=20 (occurring at the rate of 53.30% of the total amount of cells examined), 2n=18 (30.70%), and 2n=16 (15.99%) in our work. (Table 1). Since the original basic number of chromosome of the genus is 9 as proposed above, 2n= 20 would be considered as a derived one and the occurrence of 2n=18 probably suggests an early evolutionary trend of 2n=18→20 of the pecies in question.     

The cytological behavior of a human ring-chromosome

A ring chromosome derived from group 17–18 was found in a mentally retarded girl. The ring shows considerable variability. With respect to the size the ring is enlarged in 9% of the cells. In 19% of the cells the ring is eliminated; in these cells the chromosome number is only 45. The elimination of the ring has been studied. There are cytological indications of two simultaneous mechanisms: lagging and destruction of complex unstable structures.     

Formation of 9-hydroxy linoleic acid as a product of phospholipid peroxidation in diabetic erythrocyte membranes.

The increased production of oxygen-derived free radicals (OFR) and lipid peroxidation may contribute to vascular complications in diabetes. Some lipid peroxidation products have already been reported to be formed via glucose-induced oxidative stress. We have identified 9-hydroxy linoleic acid (9-OH-C18:2) in the red cell membrane phospholipid of diabetic subjects. We hypothesized that 9-OH-C18:2 would be formed in hydroxyl radical reactions to linoleic acid (C18:2) during glucose-induced oxidative stress, and confirmed that the formation of 9-OH-C18:2 was induced by ultraviolet (UV)-C irradiation to the synthetic C18:2. UV-C light generates highly reactive hydroxy radicals. C18:2 is confirmed to be the precursor of 9-OH-C18:2. To estimate the degree of oxidative damage to red cell membrane phospholipids, we developed a selective ion monitoring gas chromatography-mass spectrometric measurement for C18:2 and 9-OH-C18:2, following methanolysis of red cell membrane phospholipids. The relative peak height ratio of C18:2 to 9-OH-C18:2 (9-OH-C18:2/C18:2) was measured in phospholipid extracts of red cell membranes from healthy (n=29, 3.1+/-1.9%) and diabetic (n=27, 20. 9+/-16.1%) subjects. It was confirmed that 9-OH-C18:2/C18:2 is significantly (P<0.001) elevated in patients with diabetes. The measurement of 9-OH-C18:2/C18:2 in red cell membranes should be useful for assessing oxidative damage to membrane phospholipids in diabetes.     

The anatomy of the sheep cervix and its influence on the transcervical passage of an inseminating pipette into the uterine lumen

The anatomy of the sheep cervix is highly variable between animals and may explain the differing success of transcervical AI between individuals. This study aims to quantify the variation in cervical morphology between ewes and investigate the relationship between cervical anatomy and cervical penetration. Two series of reproductive tracts were collected. Series A: 132 adult anoestrous ewes, and series B: 165 cycling adult ewes and ewe lambs which were identified as luteal or non-luteal based on the presence of a corpus luteum. The morphology of the cervical external os was classified as slit, papilla, duckbill, flap or rose. An inseminating pipette was inserted into the lumen and the depth of penetration recorded. The cervix was opened longitudinally, its length recorded, the number of cervical rings counted and the arrangement of those rings graded. The maximum depth of cervical penetration was affected by cervical grade (series A: P=0.021; series B: P=0.037) and the stage of the oestrous cycle (P=0.008). Grade 1 cervices were more penetrable than grade 2, with grade 3 the least penetrable and non-luteal cervices could be penetrated further than luteal cervices. The distribution of os types differed with age, with rose types more common in adult ewes, and papilla os types more common in ewe lambs. These results indicate that the depth of cervical penetration is affected by the anatomy of the cervical lumen. Cervices with a less convoluted lumen (grade 1) were more penetrable. Non-luteal cervices are likely to have higher oestradiol concentrations than luteal, stimulating cervical relaxation and enabling deeper penetration. The difference in os types with age may be contributable to a morphological alteration at parturition.     

Formation of 9-hydroxy linoleic acid as a product of phospholipid peroxidation in diabetic erythrocyte membranes

The increased production of oxygen-derived free radicals (OFR) and lipid peroxidation may contribute to vascular complications in diabetes. Some lipid peroxidation products have already been reported to be formed via glucose-induced oxidative stress. We have identified 9-hydroxy linoleic acid (9-OH-C18:2) in the red cell membrane phospholipid of diabetic subjects. We hypothesized that 9-OH-C18:2 would be formed in hydroxyl radical reactions to linoleic acid (C18:2) during glucose-induced oxidative stress, and confirmed that the formation of 9-OH-C18:2 was induced by ultraviolet (UV)-C irradiation to the synthetic C18:2. UV-C light generates highly reactive hydroxy radicals. C18:2 is confirmed to be the precursor of 9-OH-C18:2. To estimate the degree of oxidative damage to red cell membrane phospholipids, we developed a selective ion monitoring gas chromatography-mass spectrometric measurement for C18:2 and 9-OH-C18:2, following methanolysis of red cell membrane phospholipids. The relative peak height ratio of C18:2 to 9-OH-C18:2 (9-OH-C18:2/C18:2) was measured in phospholipid extracts of red cell membranes from healthy (n=29, 3.1±1.9%) and diabetic (n=27, 20.9±16.1%) subjects. It was confirmed that 9-OH-C18:2/C18:2 is significantly (P<0.001) elevated in patients with diabetes. The measurement of 9-OH-C18:2/C18:2 in red cell membranes should be useful for assessing oxidative damage to membrane phospholipids in diabetes.     

Immunocytochemical staining of cervical smears for the diagnosis of cervical intraepithelial neoplasia

A total of 233 cervical smears were stained by immunocytochemical methods for epithelial membrane antigen (EMA); the findings were compared with those from Papanicolaou-stained smears from the same women. Squamous epithelial cells from normal cervices did not stain, but cells shed from cervices with cervical intraepithelial neoplasia (CIN) did express the EMA marker. Metaplastic cells from normal and abnormal cervices also frequently stained. The results confirm that this marker detects cervical intraepithelial neoplasia in vitro, but its potential use in an automated screening program may be limited by the staining of the metaplastic cells.     

Clinical and cytological differences in adult acute lymphatic and acute undifferentiated leukemia]

The usefulness for clinical purposes of the distinction of acute undifferentiated (AUL) and acute lymphocytic leukemia (ALL) is suggested by the following observations: 1. Maturation from AUL to ALL has not been observed. Transformation of ALL to AUL has been reported i.e. less of cytoplasmic polysaccharides; however this seems rather to be the effect of cytotoxic therapy and not a real change of the cytological type. 2. Significant differences among ALL and AUL can be noted as far as the therapeutic response is concerned: All of the 9 patients with ALL but only 2 out of 9 patients with AUL went into remission. The mean survival of the cases with ALL amounts to 34, that of AUL only to 4 months. Out of the patients with ALL 4 patients are still alive in persistant first remission after 77, 57, 36 and 28 months. 3. ALL occurs most frequently in young adults (mean age of 21 patients: 31.7 years): AUL is more frequent in elderly patients (Mean age of 18 patients: 57.6 years). 4. In our material ALL did never occur consequent to a typical preluekemic stage, which was followed either by myeloblastic, monocytic, erythroleukemic or undifferentiated leukemias.     

In vitro desaturation or elongation of monotrans isomers of linoleic acid by rat liver microsomes

Several nutritional studies have shown the in vivo conversion of the 9c,12t-18:2 and 9t,12c-18:2 into long chain polyunsaturated fatty acids (PUFA) containing 20 carbons (geometrical isomers of eicosadienoic and eicosatetraenoic acids). In the present work, some in vitro studies were carried out in order to have precise information on the conversion of these two isomers.In a first set of experiments, studies were focused on the in vitro 6 desaturation, the first regulatory step of the biosynthesis of n-6 long chain PUFA, from 9c,12c-18:2. Rat liver microsomes were prepared and incubated under desaturation conditions with [1-¹⁴C]-9c,12c-18:2 in presence of unlabelled 9c,12t-, 9t,12c- or 9t,12t-18:2. The data show that each trans isomer induced a decrease of the 6 desaturation of the [1-¹⁴C]-9c,12c-18:2, but the 9c,12t-18:2 was the most potent inhibitor (up to 63%). Rat liver microsomes were also incubated with [1-¹⁴C]-9c,12c-18:2, [1-¹⁴C]-9c,12t-18:2 or [1-¹⁴C]-9t,12c-18:2 under desaturation conditions. The results indicated that 18:2 9c,12t is a much better substrate for desaturase than 9t,12c-18:2. Moreover, the conversion levels of [1-¹⁴C]-9c,12t-18:2 was similar to what was observed for its all cis homologue, at low substrate concentration only. In a second set of experiments, in vitro elongation studies of each mono-trans 18:2 isomers and 9c,12c-18:2 were carried out. For that purpose, rat liver microsomes were incubated with [1-¹⁴C]-9c,12c-18:2, [1-¹⁴C]-9c,12t-18:2 or [1-¹⁴C]-9t,12c-18:2 under elongation conditions. The data show that [1-¹⁴C]-9t,12c-18:2 is better elongated than 9c,12c-18:2 while the amount of product formed from [1-¹⁴C]-9c,12t-18:2 was lower than was produced from the 9c,12c-18:2.Thus, the desaturation enzymes presented a higher affinity for the 9c,12t-18:2 whereas the elongation enzyme presented a higher affinity for the 9t,12c-18:2.     

Relationship between dilatation of the rat uterine cervix and a small dermatan sulfate proteoglycan

Cervical linear circumference (lo), extensibility and rate of creep, and the content and concentration of collagen and proteoglycans were determined on uterine cervices of rats at different reproductive stages. The inner circumference increased from 9 +/- 3 (SD) mm at the nongravid stage to a maximum of 41 +/- 5 mm at term; a significant drop to 23 +/- 2 mm occurred by 4 h postpartum with a further drop to 18 +/- 4 mm by 1 day postpartum. The extensibility and rate of creep reached their maxima 1 day before term and returned to the nongravid value by 1 day postpartum. The small (Mr = 95,000) type II dermatan sulfate proteoglycan, the major cervical proteoglycan, increased from 43 +/- 6 micrograms per cervix at the nongravid stage to 196 +/- 33 micrograms at term. The amount of this proteoglycan decreased significantly by 35% to 126 +/- 5 micrograms within 4 h postpartum and declined further to 79 +/- 16 micrograms by 1 day postpartum. The total cervical collagen content increased less than 2-fold during pregnancy, from 3.5 +/- 0.5 to 6.3 +/- 0.7 mg; a decline to 5.8 mg by 1 day postpartum was not significant. The ratio of small proteoglycan: collagen increased 2.5-fold between the nongravid state and term, then returned to the nongravid value by 1 day postpartum. Significant correlations were found between the lo and the amount of small proteoglycan per cervix (r = 0.86; n = 69) and between lo and the ratio of small proteoglycan:collagen (r = 0.83; n = 50) when data from every reproductive stage were combined. A mechanism is proposed whereby the interaction of the proteoglycan with collagen fibers might alter mechanical properties and contribute to cervical dilatation and its rapid reversal.     

THE CHROMOSOMES OF THE SEMPERVIVOIDEAE (CRASSULACEAE)

Uhl , Charles H. (Cornell U., Ithaca, New York.) Chromosomes of the Sempervivoideae (Crassulaceae). Amer. Jour. Bot. 48(2): 114–123. Illus. 1961.—Chromosome numbers are reported for 207 collections representing 68 of the ca. 95 species in this subfamily. Basic numbers are 16, 17, 18, and 19 in Sempervivum, Section Sempervivum (10 species, with many tetraploids and one hexaploid); 19 in Sempervivum, Section Jovisbarba (5 species, all diploid); 15 in Aichryson (9 species, including 1 aneuploid, 1 tetraploid, and 1 aneutetraploid); and strictly 18 in Aeonium (31 species, including 4 wholly and 1 partly tetraploid), Greenovia (3 species, 1 partly tetraploid), and Monanthes (10 species, including 2 wholly and 1 partly tetraploid). The cytological evidence appears decisive in ranking several species of disputed generic position definitely with Aichryson rather than with Aeonium. Possible relationships between various Canarian genera and certain North African species often classed in Sedum are discussed briefly in the light of the scanty morphological and cytological evidence. It is suggested that both these groups may be descended from the same ancestors that were widespread in North Africa before the deserts developed.     

Relationship of estradiol and prostaglandins in sperm retention in the mated rabbit

Estradiol-17β (3 μg), administered 1 hr before mating, significantly increased sperm retention in oviducts, uterus, cervices and vagina of does at 2 hr after mating. Indomethacin itself, administered 1.5 hr before mating, reduced the prostaglandin F₂α concentration in the uterus and reduced the number of sperm recovered from the oviducts, cervices and vagina, but indomethacin did not block the estradiol-induced increase in sperm retention in the reproductive tract. Increased sperm retention due to estradiol is probably not mediated solely by prostaglandin F₂α.     

Resonance Raman studies of the stoichiometric catalytic turnover of a substrate-stearoyl-acyl carrier protein delta(9) desaturase complex

Resonance Raman spectroscopy has been used to study the effects of substrate binding (stearoyl-acyl carrier protein, 18:0-ACP) on the diferric centers of Ricinus communis 18:0-ACP Delta(9) desaturase. These studies show that complex formation produces changes in the frequencies of nu(s)(Fe-O-Fe) and nu(as)(Fe-O-Fe) consistent with a decrease in the Fe-O-Fe angle from approximately 123 degrees in the oxo-bridged diferric centers of the as-isolated enzyme to approximately 120 degrees in oxo-bridged diferric centers of the complex. Analysis of the shifts in nu(s)(Fe-O-Fe) and nu(as)(Fe-O-Fe) as a function of 18:0-ACP concentration also suggests that 4e(-)-reduced Delta9D containing two diferrous centers has a higher affinity for 18:0-ACP than resting Delta9D containing two diferric centers. Catalytic turnover of a stoichiometric complex of 18:0-ACP and Delta9D was used to investigate whether an O-atom from O(2) would be incorporated into a bridging position of the resultant mu-oxo-bridged diferric centers during the desaturation reaction. Upon formation of approximately 70% yield of 18:1-ACP product in the presence of (18)O(2), no incorporation of an (18)O atom into the mu-oxo bridge position was detected. The result with 18:0-ACP Delta(9) desaturase differs from that obtained during the tyrosyl radical formation reaction of the diiron enzyme ribonucleotide reductase R2 component, which proceeds with incorporation of an O-atom from O(2) into the mu-oxo bridge of the resting diferric site. The possible implications of these results for the O-O bond cleavage reaction and the nature of intermediates formed during Delta9D catalysis are discussed.     

Chromosomal sex and distribution of functional germ cells in a series of chimeric mice

An unselected series of chimeric mice were test mated to determine the parental lineage of their functional gametes. The cytological sex of each animal was established and confirmed in all cases by karyological analysis of peripheral blood lymphocytes. The parental cell lineage for each cytological sex was unequivocally established by the presence or absence of the radiation-induced translocation 15(14) (T6). Eleven animals analysed, 10 of these were chimeric. Among the 10 chimeras, 3 were phenotypically female and 7 were phenotypically male. The cytological sex ratio (XY/XY:XX/XY:XX/XX) was 1:6:2. There were 646 offspring from test matings of these chimeras. The coat color analysis of these offspring demonstrated a concordance of cytological sex of the lineage resulting in functional gametes with the phenotypic sex of the animal.     

Identification and analysis of a gene from Calendula officinalis encoding a fatty acid conjugase

Two homologous cDNAs, CoFad2 and CoFac2, were isolated from a Calendula officinalis developing seed by a polymerase chain reaction-based cloning strategy. Both sequences share similarity to FAD2 desaturases and FAD2-related enzymes. In C. officinalis plants CoFad2 was expressed in all tissues tested, whereas CoFac2 expression was specific to developing seeds. Expression of CoFad2 cDNA in yeast (Saccharomyces cerevisiae) indicated it encodes a Delta12 desaturase that introduces a double bond at the 12 position of 16:1(9Z) and 18:1(9Z). Expression of CoFac2 in yeast revealed that the encoded enzyme acts as a fatty acid conjugase converting 18:2(9Z, 12Z) to calendic acid 18:3(8E, 10E, 12Z). The enzyme also has weak activity on the mono-unsaturates 16:1(9Z) and 18:1(9Z) producing compounds with the properties of 8,10 conjugated dienes.     

Catalytic convergence of manganese and iron lipoxygenases by replacement of a single amino Acid

Lipoxygenases (LOXs) contain a hydrophobic substrate channel with the conserved Gly/Ala determinant of regio- and stereospecificity and a conserved Leu residue near the catalytic non-heme iron. Our goal was to study the importance of this region (Gly(332), Leu(336), and Phe(337)) of a lipoxygenase with catalytic manganese (13R-MnLOX). Recombinant 13R-MnLOX oxidizes 18:2n-6 and 18:3n-3 to 13R-, 11(S or R)-, and 9S-hydroperoxy metabolites (～80-85, 15-20, and 2-3%, respectively) by suprafacial hydrogen abstraction and oxygenation. Replacement of Phe(337) with Ile changed the stereochemistry of the 13-hydroperoxy metabolites of 18:2n-6 and 18:3n-3 (from ～100% R to 69-74% S) with little effect on regiospecificity. The abstraction of the pro-S hydrogen of 18:2n-6 was retained, suggesting antarafacial hydrogen abstraction and oxygenation. Replacement of Leu(336) with smaller hydrophobic residues (Val, Ala, and Gly) shifted the oxygenation from C-13 toward C-9 with formation of 9S- and 9R-hydroperoxy metabolites of 18:2n-6 and 18:3n-3. Replacement of Gly(332) and Leu(336) with larger hydrophobic residues (G332A and L336F) selectively augmented dehydration of 13R-hydroperoxyoctadeca-9Z,11E,15Z-trienoic acid and increased the oxidation at C-13 of 18:1n-6. We conclude that hydrophobic replacements of Leu(336) can modify the hydroperoxide configurations at C-9 with little effect on the R configuration at C-13 of the 18:2n-6 and 18:3n-3 metabolites. Replacement of Phe(337) with Ile changed the stereospecific oxidation of 18:2n-6 and 18:3n-3 with formation of 13S-hydroperoxides by hydrogen abstraction and oxygenation in analogy with soybean LOX-1.     

Presence of regio-isomeric cholesteryl linoleate hydroperoxides and hydroxides in plasma from healthy humans as evidence of free radical-mediated lipid peroxidation in vivo

Abstract

Lipid hydroperoxides are the primary stable products of lipid peroxidation. We have developed an ultrasensitive method for the detection of lipid hydroperoxides¹ and found about 3 nM cholesteryl ester hydroperoxides (CE-OOH), mostly cholesteryl linoleate hydroperoxides (Ch18:2-OOH), in blood plasma obtained from healthy subjects.² Autoxidation of cholesteryl linoleate (Ch18:2) gives cholesteryl 13-hydroperoxy-9Z,11E-octadecadienoate (13ZE-Ch18:-OOH), cholesteryl 13-hydroperoxy-9E,11E-octadecadienoate (13EE-Ch18:2-OOH), cholesteryl 9-hydroperoxy-10E,12Z-octadecadienoate (9EZ-Ch18:2-OOH), and cholesteryl 9-hydroperoxy-10E,12E-octadecadienoate (9EE-Ch18:2-OOH). Enzymatic oxidation of Ch18:2 with 15-lipoxygenase gives predominantly only one product (13ZE-Ch18:2-OOH).³ To help elucidate the production mechanisms of cholesteryl linoleate hydroperoxides in vivo, we examined the distribution of Ch18:2-O(O)H regioisomers in human blood plasma.