The relationship between trinucleotide repeat length and phenotypic variation in Machado-Joseph disease

Trinucleotide repeat expansion in the Machado-Joseph disease (MJD) gene has been found in 26 patients from 20 unrelated Japanese families. Expanded alleles had 68 to 84 repeats, whereas normal alleles had 14 to 37 repeats. The age of onset was inversely correlated with the repeat length. To evaluate in detail the relationship between the repeat length and clinical features, we subdivided the 26 patients into three groups on the basis of the repeat length (group 1, 78 repeats or more; group 2, 74 to 77 repeats; group 3, 73 repeats or less). Group 1 and group 2 had common features of spasticity, hyperreflexia, Babinski sign, bulging eyes, facial myokymia and extrapyramidal signs as well as cerebellar ataxia and ophthalmoplegia. It should be noted that group 1 showed more prominent pyramidal and extrapyramidal signs than group 2. In contrast, group 3 showed hypotonia, hyporeflexia and sensory disturbance in addition to cerebellar ataxia and ophthalmoplegia. These findings suggest that the repeat length plays an important role in phenotypic variation. DNA analysis for the MJD mutation was clearly useful for making an accurate diagnosis in patients without bulging eyes, facial myokymia, dystonia or marked spasticity.

Proadrenomedullin N-terminal 20 peptide is rapidly cleaved by neutral endopeptidase

Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide which is processed from an adrenomedullin precursor. PAMP is rapidly cleaved by human neutral endopeptidase (NEP), a protease which plays a key role in the degradation of human atrial natriuretic peptide (ANP). A double reciprocal plot indicated that Km of NEP as a substrate of PAMP was 6.1 microM and V(max) was 3.1 mmol/min/mg of NEP. EDTA, phosphoramidon and thiorphan inhibit the proteolysis of PAMP by NEP. NEP cleaves at least 6 peptide bonds in human PAMP; Arg2-Leu3, Glu8-Phe9, Lys12-Trp13, Lys15-Trp16, Trp16-Ala17 and Ala17-Leu18. The present data suggest that NEP may be involved in the circulation control by degrading PAMP as well as ANP.

15-Hydroperoxyeicosapentaenoic acid inhibits arachidonic acid metabolism in rabbit platelets more potently than eicosapentaenoic acid

The effect of 15-hydroperoxy-5,8,11,13,15-eicosapentaenoic acid (15-HPEPE), a hydroperoxy adduct of eicosapentaenoic acid (EPA), on the formation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), thromboxane (TX) B2 and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) from exogenous arachidonic acid in washed rabbit platelets was examined. 15-HPEPE inhibited 12-HETE, TXB2 and HHT formation at concentrations ranging from 2 to 8 microM. The inhibitory effect of 15-HPEPE was dose-dependent (12-HETE, 16.0-82.9% inhibition; TXB2, 16.7-57.2% inhibition; HHT, 4.6-52.0% inhibition). EPA inhibited the production of these three metabolites, but the inhibitory effect was kept low (20-100 microM: 12-HETE, 8.3-31.1% inhibition; TXB2, 18.9-49.5% inhibition; HHT, 12.5-41.7% inhibition) as compared with 15-HPEPE. Experiments utilizing 15-hydroxy-5,8,11,13,15-eicosapentaenoic acid and hydroxyl radical scavengers (dimethyl sulfoxide and mannitol) revealed that 15-HPEPE exerted its effect in the form of the hydroperoxy adduct. These results suggest that 15-HPEPE has the potential to modulate the activities of the cyclo-oxygenase and 12-lipoxygenase in platelets. This may also be one convincing mechanism for the anti-thrombotic and anti-atherosclerotic actions of EPA.

Effect of Prograf (FK506) on spermatogenesis in rats

Prograf (FK506) was given to male mature rats in a daily subcutaneous dose of 1 or 3 mg/kg/day for 2 weeks to investigate its effect on spermatogenesis. Prograf dose-dependently sperm counts and motility, but did not affect testosterone level in the serum of rats. Histopathologically, there were no abnormal changes in the testis, seminal vesicle or prostate in any rats dosed with Prograf, but intra-ductal eosinophilic globules, probably degeneration of the sperm cells, were observed in the epididymis of the 3 mg/kg/day group. Sperm counts and motility returned to the control levels after stopping of the drug. The results indicate that Prograf decreased sperm counts and motility through direct action on the sperm in the epididymis, but not the production of sperm in the testis. Cyclosporine A (CsA) was used as the reference drug in the present study. Thirty mg/kg/day of CsA also decreased sperm counts and motility, and stopping of the drug led to the recovery of these changes. The males dosed with Prograf for 2 weeks were mated with non-dosed females to investigate its effect on the fertility potential of the males. Prograf did not affect copulation or fertility index, but a decrease in the number of live fetuses associated with implantation loss was observed in the 3 mg/kg/day group. The changes were considered to be due to the decrease of sperm counts and motility, although 1 mg/kg/day of Prograf, 5-10 times the clinical dose, did not affect any fertility parameters including implantation index.

An antibody specific to N-terminal amino acid sequence of human maternal serum cystine aminopeptidase and its applications

An antibody directed against a synthetic peptide corresponding to the N-terminal sequence of human cystine aminopeptidase (CAP) present in maternal serum was prepared. Although the antibody did not immunoprecipitate the activity of CAP, it was useful for purification and immunoblot analysis of CAP protein. An antipeptide antibody-conjugated Sepharose 4B column was very effective in purifying a single CAP protein from partially purified enzyme preparation, and Western blotting confirmed the binding of the antibody to CAP protein.

[Studies on the bioactive constituents of Aurantii Fructus Immaturus]

An ethanol extract of "Kijitsu" (Aurantii Fructus Immaturus, Citrus aurantium L.) collected in China was assessed for the antitumor activity using murine leukemia P388 in vivo, and the extract was found to be active by the antitumor bioassay in vivo and in vitro. The extract was separated into a petroleum ether-soluble fraction and an ethyl acetate-soluble fraction. Fractionation was carried out using an index of cell-growth inhibitory activity against mouse leukemia L1210 cells to isolate antitumor active substances or compounds. The active compounds were purified employing silica gel column chromatography and HPLC. The antitumor effect of the isolated active compounds was studied. Five compounds, auraptene, marmin, tangeretin, nobiretin and 5-[(6',7'-dihydroxy-3',7'-dimethyl-2-octenyl)oxy]psoralen were isolated from Citrus aurantium L. Though they are all known compounds, 5-(6',7'-dihydroxy-3',7-dimethyl-2-octenyl)oxy-psoralen from this plants was first isolated. These compounds showed a cell-growth inhibitory effect against L1210 and K562 in vitro.

Effects of Fe(2+), Zn(2+), Cu(2+) and Se(4+) on the synthesis and catabolism of prostaglandins in rabbit gastric antral mucosa

Effects of Fe(2+), Zn(2+), Cu(2+) and Se(4+) on the synthesis and catabolism of prostaglandins (PGs) in rabbit gastric antral mucosa were examined. Fe(2+) inhibited the cyclooxygenase activity in the microsomal fraction. Zn(2+) suppressed the endoperoxide E(2) isomerase activity in the microsomal fraction and the 15-hydroxy PG dehydrogenase (PGDH) activity in the cytosolic fraction. Cu(2+) stimulated the cyclooxygenase activity, inhibited the PGDH activity and possibly induced non-enzymatic reduction of PGG(2) or PGH(2) to PGF(2 alpha) Se(4+) possibly induced the non-enzymatic reduction of PGG(2) or PGH(2) to PGF(2 alpha), as well as Cu(2+). These results suggest that Fe(2+), Zn(2+), Cu(2+) and Se(4+) can be modulators of the gastric antral mucosal PG levels by affecting the PG synthesizing enzymes, PG catabolizing enzyme and/or non-enzymatic reduction of PGG or PGH to PGF.

Phloroglucinols from Baeckea frutescens

Two new phloroglucinols, named BF-1 and BF-2, were isolated from the dried leaves of Baeckea frutescens. Their structures were determined by their 1H and 13C NMR and mass spectral data. BF-2 exhibited strong cytotoxic activity (IC50 = 5.0 micrograms ml-1) against leukaemia cells (L 1210) in tissue culture.

[A case of toxic shock syndrome (TSS) induced by methicillin-resistant staphylococcus aureus (MRSA) presenting as acute renal failure with disseminated intravascular coagulation]

A case of a 73-year-old woman with acute renal failure due to toxic shock syndrome (TSS) is reported. The patient was admitted to our hospital with the complaints of high fever, disturbance of consciousness and shock. Laboratory findings on admission were; CRP 25.11 mg/dl, WBC 35000/ microl, Plt 1.6 x 10(4)/ microl, GOT 155 U/l, GPT 65 U/l, CPK 4202 U/l (CPK-MM 96%), BUN 123 mg/dl and SCr 7.0 mg/dl. Because of anuria, hemodialysis was performed. This patient was treated with dopamine, methyl prednisolone (MP), frozen fresh plasma, AT III, antibiotics, and platelet transfusion. The bacterial cultures of blood and cerebrospinal fluid were negative, but MRSA was isolated subsequently from the pharynx and vagina. We investigated the production of toxic shock syndrome toxin 1 (TSST-1) and staphylococcal enterotoxins (SE). The isolated MRSA produced TSST-1, SEB and SEC. Accordingly, we made the diagnosis of TSS. After improvement of acute renal failure and the patient's general condition, MRSA persisted and TSST-1 was still found in the patient's blood. Finally we eradicated the MRSA and TSST-1 after administration of ciprofloxacin hydrochloride (CPFX) and Rifampicin (RFP).

Is CD26/dipeptidyl peptidase IV a really important molecule in T cell activation of a certain rat strain?

A new monoclonal antibody (MS-7 mAb) was raised to investigate the real role of the membrane-associated molecule CD26/dipeptidyl peptidase IV (DPP IV; EC 3.4.14.5), which transduces activation signals in T cells. A strain of rats which is deficient in DPP IV was used. MS-7 mAb recognized DPP IV (110 kDa) and its 60 kDa fragment, starting at the 281st residue corresponding to the extracellular one comprising the active-site sequence Gly-X-Ser631-X-Gly of DPP IV. MS-7 mAb recognized CD26 on T cells of DPP IV+ rats both before and after mitogen activation. CD26 expression and DPP IV enzyme activity are increased on T cells following their activation; nevertheless, no CD26 was expressed on T cells of DPP IV- rats, and no DPP IV enzyme activity was detected either before or after mitogen activation. In addition, MS-7 mAb inhibited the mitogen-stimulated proliferation of DPP IV+ rats, but did not affect that of DPP IV- rats. These results suggest that CD26/DPP IV is not a necessary molecule in T cell activation, and that there is some other bypass in T cell activation of DPP IV- rats.

Characterization of gelatinases in human placenta

Matrix metalloproteinases were extracted from human placenta. Gelatin zymograms showed four bands with gelatinase activity. These four bands were detected at Mr 72,000, 92,000, 130,000, and 210,000 respectively. Reduced and alkylated samples were detected at Mr 72,000 and 92,000. Immunoblotting analysis showed that the enzymes of Mr 130,000 and 210,000 were derived from gelatinase B (EC 3.4.24.35). Also, reduced gelatinase was activated by 4-aminophenylmercuric acetate more readily than a nonreduced gelatinase. This indicates that human placental gelatinases are stabilized by the tissue inhibitor of metalloproteinases.

Effects of fatty acids and fatty acyl CoA esters on Cu(2+)-induced conversion of xanthine dehydrogenase to oxidase in rabbit liver

Effects of various fatty acids and fatty acyl CoA esters on Cu(2+)-induced conversion of xanthine dehydrogenase to oxidase in rabbit liver were examined. Cu2+ (2-10 microM) brought about the conversion of xanthine dehydrogenase to oxidase in a dose-dependent manner. Oleic, arachidonic, eicosapentaenoic, and docosahexaenoic acids (50-200 microM) prevented the conversion of xanthine dehydrogenase to oxidase catalyzed by 6 microM-Cu2+. The effect of these four fatty acids was concentration-dependent, whereas palmitic, stearic, and linoleic acids had no effect on the conversion of xanthine dehydrogenase to oxidase at the same concentration range. On the other hand, palmitoyl, linoleoyl, and arachidonoyl CoAs elicited the inhibition of 6 microM-Cu(2+)-induced conversion of xanthine dehydrogenase to oxidase at concentrations of 50, 100, and 200 microM. These results suggest that oleic, arachidonic, eicosapentaenoic and docosahexaenoic acids, and fatty acyl CoAs have the potential to inhibit the conversion of xanthine dehydrogenase to oxidase in rabbit liver.

Changes in free radical-metabolizing enzymes and lipid peroxides in the liver of Long-Evans with cinnamon-like coat color rats

We report changes in free radical-metabolizing enzymes and the increased generation of lipid peroxides associated with extreme metal accumulation in the liver of the Long-Evans with cinnamon-like coat color (LEC) rat, a new mutant strain displaying hereditary hepatitis and subsequent hepatocellular carcinoma. The activity of free radical-metabolizing enzymes and lipid peroxides, and the concentration of metal in the liver were determined sequentially after birth. Mn-superoxide dismutase activity significantly increased immediately after the onset of hepatitis in LEC rats, whereas no remarkable change was observed in control rats. Cu, Zn-superoxide dismutase activity in LEC rats was similar to that in control rats. Glutathione reductase activity increased, while glutathione peroxidase activity was lower in LEC rats than in control rats throughout the observation periods. Lipid peroxides, estimated by thiobarbituric acid reaction, also increased 4- to 5-fold immediately after the onset of hepatitis in LEC rats. Copper concentration was 30- to 50-fold higher in the liver of LEC rats than in control rats, and the iron content also increased significantly before and after the onset of hepatitis. These findings suggested that an oxidant injury generated by toxic metals could be one of the factors responsible for hepatocellular damage in this unique hereditary hepatitis.

A far-upstream sequence of the wheat histone H3 promoter functions differently in rice and tobacco cultured cells

The cis-regulatory function of a far-upstream sequence (-1,711 to -186) of the promoter of the wheat gene for histone H3 (TH012) was analyzed in cultured rice and tobacco cells in a transient expression system with the gene for beta-D-glucuronidase as a reporter gene. The far-upstream sequence was necessary for full activity of the H3 promoter in rice cells but did not enhance the activity of the proximal promoter in tobacco cells. Dissection analysis of the far-upstream sequence revealed the existence of several positive and negative cis-acting sequences in this region, some of which functioned differently in rice and tobacco cells. In gain-of-function experiments with rice cells, the sequence from -848 to -704, containing the CCAAT and octamer (CaCGGATC) motifs, functioned in an orientation-independent manner, whereas the sequence from -703 to -486 functioned in an orientation-dependent manner. By contrast, both sequences exhibited an orientation-dependent cis-function in tobacco cells. These findings suggest that some cis-regulatory sequences in the far-upstream region of the H3 promoter function differently in rice and tobacco cells.

Hederagenin glycosides from Pometia eximia

Seven new saponins, all glycosides of hederagenin (3 beta,23- dihydroxyolean-12-en-28-oic acid), were isolated from the stem of Pometia eximia along with hederagenin and two known saponins. Their structures were established as 28-O-beta-D-apiosyl(1-->2)-beta-D-glucopyranosyl-, 3-O-alpha-L- arabinofuranosyl(1-->3)[alpha-L-rhamnopyranosyl (1-->2)]-beta-D- xylopyranosyl-, 3-O-beta-D-apiosyl(1-->3)[alpha-L-rhamnopyranosyl-(1-->2)-beta-D- glucopyranosyl-, 3-O-alpha-L-arabinofuranosyl(1-->3)[alpha-L-rhamnopyranosyl- (1-->2)]-beta-L-arabinopyranosyl-, 3-O-beta-D-xylopyranosyl(1-->3)[alpha-L- rhamnopyranosyl(1-->2)]-alpha-L-arabinopyranosyl-, 3-O-beta-D-xylopyranosyl-(1-->3)[alpha-L-rhamnopyranosyl(1-->2)]-beta-D- glucopyranosyl-, 3-O-beta-D-galactopyranosyl(1-->3)[alpha-L-rhamnopyranosyl(1-->2)]-beta- D- glucopyranosyl-hederagenins.

Inhibition of food-borne pathogenic bacteria by bacteriocins from Lactobacillus gasseri

Lactobacillus acidophilus group and a Lact. reuteri isolated from human faeces were examined for production of antimicrobial agents against 16 strains of six species of food-borne enteric pathogenic bacteria. Several strains of Lact. gasseri showed wide inhibitory activity against the tested bacteria. Gassericin A produced by Lact. gasseri LA39 was one of the most widely active bacteriocins. It was bactericidal without causing cell lysis.

Biological activities of Annona glabra

On a preliminary screening, substantial antimicrobial, antifungal and moderate insecticidal, sporicidal and cytotoxic activities were observed for the hexane extract of the stem bark of Amona glabra L. Chromatographic fractionation of this extract led to the isolation of kaur-16-en-19-oic acid in a large amount as the main constituent, which was found to be largely responsible for the biological activities possessed by the crude extract.

Midbrain paralemniscal projections to the facial nucleus: an anatomical and immunohistochemical study

Serial 30 microns-thick sections through the midbrain tegmentum were stained with cresyl violet. The PL was found to be situated along the medial edge of the lateral lemniscus. The PL consisted of small- (10-15 microns) and medium-sized neurons (25-35 microns), and was the most prominent at the caudal level of the superior colliculus. In order to confirm the existence of the inhibitory paralemniscal-facial pathway, a combined HRP and immunohistochemical technique was use in the rat. This experiment revealed that 10.9% of the total number of GABA immunoreactive PL neurons also labeled with HRP after HRP injection was made in the medial part of the facial nucleus (FN). Electron microscopic observations were carried out on the medial part of the facial nucleus (FN) after kainic acid injection was made into the contralateral PL in the cat. The majority of degenerating PL fibers were ranged from 0.5 to 3.1 microns in diameter and made synaptic contacts with somata, proximal dendrites and dendritic profiles. These fibers, containing either round or pleomorphic vesicles, formed asymmetrical or symmetrical synapses. It was of particular interest in the present study that 40.7% of the total number of degenerating fibers make synaptic contacts with large dendrites more than 3.0 microns in diameter.

Structure-activity correlationship and strain specificity of polyoxometalates in anti-human immunodeficiency virus activity

The anti-human immunodeficiency virus (HIV) activity of polyoxometalates of representative structural families, such as Keggin, lacunary Keggin, trivacant Keggin, Keggin sandwich, Wells-Dawson and Wells-Dawson sandwich, was determined using two strains of HIV type 1 (HIV-1HTLV-IIIB and HIV-1SF-2H). The compounds were preferably selected to cover both polyoxotungstates and polyoxomolybdates in each structural family. In general, polyoxotungstates of Keggin, lacunary Keggin, trivacant Keggin, Keggin sandwich, Wells-Dawson and Wells-Dawson sandwich structures showed anti-HIV-1HTLVIIIB activity, whereas most compounds not included in these structural categories were inactive. Among the compounds with a potent anti-HIV-1HTLV-IIIB activity, those of Keggin and its closely related structural families (lacunary Keggin, trivacant Keggin and Keggin sandwich) inhibited the cytopathogenicity and syncytium formation caused by HIV-1SF-2 to a much higher extent compared with HIV-1HTLV-IIIB-related ones. The difference between the spectra of anti-HIV-1HTLV-IIIB activity and the specificity for HIV-1SF-2H might result from differential structural requirements in these functions.

Identification of an alanine aminopeptidase in human maternal serum as a membrane-bound aminopeptidase N

In addition to cystine aminopeptidase (oxytocinase) alanine aminopeptidase is present at high levels in the serum of pregnant women. In this study we compared the enzyme with membrane-bound aminopeptidase N purified from human placenta. Comparison of catalytic and immunological properties and N-terminal sequence analyses revealed that the enzymes were differentially processed derivatives of the same protein, and that the N-terminal 68 residues of aminopeptidase N were deleted in the alanine aminopeptidase. The deleted sequence contains a small cytoplasmic region, a hydrophobic transmembrane domain and a junctional domain. These results suggest that the enzyme may be released into the maternal circulation as a result of lacking these three domains.

[A study of heel-knee tapping test in cerebellar ataxia by a motion measurement system]

It is often difficult to estimate slight alterations in the severity of ataxia by bed-side neurological examinations. We analyzed the heel-knee tapping test, which has often been used as a standard bed-side examination to check incoordination in lower limbs, using a new motion measurement system "video/computer motion measurement system". We studied 9 normal controls and 21 patients with spinocerebellar degenerations (SCD). In patients with SCD, the up-and-down motion range of the heel was variable and the heel moved in the anterior-and-posterior direction, because of knee sways during the test. Following oral administration of TRH analogue, TA-0910, above-mentioned findings were clearly improved. Analysis of spatial and time elements of the knee joint demonstrated quantitative improvement. Therefore, an effect of TA-0910 on incoordination of the lower limbs could be proved objectively by a computer motion measurement system.

Cold acclimation induces zonal heterogeneity in gluconeogenic responses to glucagon in rat liver lobule

The relationship between the enhanced responses of gluconeogenesis to norepinephrine (NE) and glucagon and its zonal distribution was studied in liver lobules of cold-exposed rats by examination of preparations enriched for periportal hepatocytes (PP-H) and for perivenous hepatocytes (PV-H) by the digitonin-collagenase perfusion technique. In the control group, gluconeogenesis from lactate (10 mM) plus pyruvate (1 mM) was higher in PP-H than in PV-H. NE (100 nM) and glucagon (100 nM) increased the rate of gluconeogenesis by 80 and 70%, respectively, in both PP-H and PV-H. Gluconeogenesis in PP-H was unchanged by cold exposure. The rate in PV-H increased to the rate in PP-H at 5 days after cold exposure, and then the rate returned to the control value at 20 days. The gluconeogenic response to the alpha-adrenergic action of NE in both PP-H and PV-H doubled after 5 days. The response to glucagon tripled in PP-H and was cut in half in PV-H after 20 days. Phorbol 12-myristate 13-acetate (PMA; 1 microM), A-23187 (100 nM), and dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP; 1 mM) increased the rate of gluconeogenesis by 200, 100, and 80%, respectively, in both PP-H and PV-H from the control group. The responses to PMA and A-23187 were unchanged by exposure to cold. The response to DBcAMP was doubled in PP-H and was cut in half in PV-H after 20 days of cold exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Novel assay system favorable for the study of cell-to-cell transmission of HIV-1 and its application to the evaluation of anti-HIV drugs

The cell-to-cell transmission of human immunodeficiency virus type 1 (HIV-1) was studied using MOLT-4 cells chronically infected with a variant strain of HIV-1SF-2 (MOLT-4/HIV-1SF-2H) and CD4+ human lymphoid MT-4 cells. MOLT-4/HIV-1SF-2H cells produced less than 1 TCID50 infectious particles per day as determined by the cytopathogenicity in MT-4 cells. However, the expression of envelope glycoproteins gp120 and gp41 on the MOLT-4/HIV-1SF-2H cell membrane was satisfactory for syncytium formation with the uninfected MOLT-4 cells. When MOLT-4/HIV-1SF-2H and MT-4 cells were co-cultured, severe cytopathogenicity was observed in MT-4 cells without being accompanied by the formation of multi-nucleated cells. Thus, the system consisting of MOLT-4/HIV-1SF-2H and MT-4 cells is convenient for exclusive study of the mechanism of cell-to-cell transmission of HIV-1. Using various compounds, it was confirmed that cell-to-cell transmission required both gp120/gp41-CD4 binding and de novo DNA synthesis.

Effects of fatty acyl coenzyme A esters on lipoxygenase and cyclooxygenase metabolism of arachidonic acid in rabbit platelets

The effects of fatty acyl coenzyme A (CoA) esters (palmitoyl-, stearoyl-, oleoyl-, linoleoyl- and arachidonoyl--CoA) on the activities of lipoxygenase and cyclooxygenase in rabbit platelets were examined. Palmitoyl-, stearoyl-, oleoyl- and linoleoyl- CoA were potent inhibitors of platelet lipoxygenase activity. In addition to the lipoxygenase, the four fatty acyl-CoA esters elicited inhibitory activity on platelet cyclooxygenase, although the inhibition was a little weaker. The CoA derivative of the icosanoid precursor arachidonic acid (AA) showed little inhibition on lipoxygenase and cyclooxygenase. Palmitic, stearic and oleic acids had little or no effect on lipoxygenase and cyclooxygenase, in contrast with their CoA derivatives. Linoleic acid was more potent than linoleoyl-CoA as an inhibitor of the cyclooxygenase, but it was a weak inhibitor of the lipoxygenase. These results suggest that the CoA derivatives of palmitic, stearic, oleic and linoleic acids have the potential to modulate both platelet lipoxygenase and cyclooxygenase activities and may have functional effects within platelets.