Effects of orally administered ethyl ester of eicosapentaenoic acid (EPA; C20:5, ω-3) on PGI2-like substance production by rat aorta

A highly purified ethyl ester of EPA (EPAEE) (74%) was manufactured from sardine oil. Sixty mg/kg/day of EPAEE was given orally to male Wishar rats for 8 weeks. No side effect or toxicity from the administration of EPAEE was observed. Plasma EPA concentration and the ratio of EPA to arachidonic acid were significantly increased, compared with control Wistar rats. An enhancement of PGI₂-like substance production by aortas obtained from rats fed EPAEE was noted. Conversion of EPA to Λ¹⁷-6-keto-PGF_1α, a stable metabolite of PGI₃, could not be detected by an incubation study of ¹⁴C-EPA and aortas either from rats fed EPAEE or from control rats. Therefore, PGI₂-like substance produced by rat aorta is most likely to be PGI₂. itself and not PGI₃.     

Simultaneous determination of triazolo-benzophenone [2′,5-dichloro-2-(3-glycylaminomethyl-5-methyl-4H-1,2,4-triazol-4-yl)-benzophenone] and its major blood metabolite, triazolam, in monkey plasma by electron-capture gas—liquid chromatography

A gas—liquid chromatographic method for the simultaneous determination of triazolobenzophenone [2′,5-dichloro-2-(3-glycylaminomethyl-5-methyl-4H-1,2,4-triazol-4-yl)-benzophenone, TB] and its major blood metabolite, triazolam, 8-chloro-6-(o-chlorophenyl)-1-methyl-4H-s-triazolo[4,3-a][1,4]benzodiazepine (TZ), in monkey plasma was developed. Decomposition of TB was observed during gas—liquid chromatography. In alkaline medium, TB in plasma was submitted to ring closure reaction to yield triazolo-aminoquinoline, [4-amino-7-chloro-5-(2-chlorophenyl)-1-methyl-4H-s-triazolo[4,3-a]quinoline (TAQ), while TZ remained unaffected, and TAQ and TZ in the benzene extract were assayed by gas—liquid chromatography using an electron-capture detector. The concentration ranges studied were from 5 to 40 ng of TB per 0.5 ml of plasma and from 2 to 20 ng of TZ per 0.5 ml of plasma. This method could be applied to the determination of the plasma levels of TB and TZ in monkeys following intravenous administration of a single 0.2 mg/kg dose of TB.     

Repair of ultraviolet radiation damage in xeroderma pigmentosum cells belonging to complementation group F

DNA-repair characteristics of xeroderma pigmentosum belonging to complementation group F were investigated. The cells exhibited an intermediate level of repair as measured in terms of (1) disappearance of T4 endonuclease-V-susceptible sites from DNA, (2) formation of ultraviolet-induced strand breaks in DNA, and (3) ultraviolet-induced unscheduled DNA synthesis during post-irradiation incubation. The impaired ability of XP3YO to perform unscheduled DNA synthesis was restored, to half the normal level, by the concomitant treatment with T4 endonuclease V and ultraviolet-inactivated Sendai virus. It is suggested that xeroderma pigmentosum cells of group F may be defective, at least in part, in the incision step of excision repair.     

Chirality of the acyl group of β-hydroxy-β-methylglutarylhydroxyabscisic acid

The β-carbon of the acyl group of β-hydroxy-β-methylglutarylhydroxyabscisic acid was shown to possess R-configuration by HPLC analysis of the reduced product.     

Induction of Haploid Callus from Isolated Microspores of Peony in vitro

The in vitro culture of isolated microspores of two cultivarsof Paeonia, P. lactiflora cv. "Kumoinotsuru" (2n=10) and cv."Toyonoakari" (2n = 10), was attempted. With both cultivars,some cultured microspores (3–6%) began to divide afterfive to seven days of culture. Those of "Kumoinotsuru" grewinto calli, whereas the others degenerated. Cytological examinationof the callus developed from a microspore revealed haploids,diploids or a mixture of both. No direct embryo formation frommicrospores was observed in this experiment. (Received December 1, 1980; Accepted January 16, 1981)     

Purification and Characteristics of Sorbitol-6-phosphate Dehydrogenase from Loquat Leaves

To study the role of sorbitol-6-phosphate dehydrogenase in sorbitol synthesis in leaves of Rosaceous plants, properties of the enzyme and its presence in several plants in the family was investigated. The activity of the enzyme, which catalyzes an NADP-dependent oxidation of the substrate to glucose-6-phosphate, was detected in leaves of Prunus mume, Prunus persica, Rhaphiolepsis indica, Sorbus aucuparia, Cydonia oblonga, Photinia glabra, Sorbaria kirilowii, and Spiraea thunbergii.     

Effect of cryogenic preservation (−80 °C) on polymorphonuclear neutrophil integrity as determined by biochemical analysis

The effect of cryopreservation on plasma membrane and granule associated enzymes of polymorphonuclear neutrophils (PMNs) was studied. The activity of PMNs to generate superoxide anions during phagocytosis was very sensitive to cryopreservation and exhibited approximately 60% inhibition in 24 hr. The total enzyme activity was not as affected during 1-month cryopreservation as that observed with the extracellular release of enzymes. Acid p-nitrophenyl phosphatase and peroxidase were released slightly from frozen and thawed PMNs. However, the extracellular release of LDH, a cytosol marker, and β-glucuronidase and lysozyme, granuleassociated enzymes, increased with cryopreservation time. The degree of release of these enzymes was LDH > β-glucuronidase > lysozyme. A considerable amount of LDH was extracellularly released after 1-month storage. Frozen and thawed PMNs became sensitive to hypotonic solutions, although fresh, nonfrozen PMNs were very resistant to hypotonic lysis. The hypotonic fragility increased even after 1 hr of cryopreservation.Addition of ATP to the preservation medium did not improve enzyme activity, enzyme release, or stimulated superoxide anion generation but increased the hypotonic fragility of PMNs. However, albumin showed protective effects against cryopreservation injury to the O₂^?-generating system, the extracellular enzyme release, and osmotic fragility.     

Fast polyspermy block and activation potential : Correlated changes during oocyte maturation of a starfish

Sperm entry into the oocyte of the starfish, Asterina pectinifera, was prevented when the membrane potential of the oocyte was held more positive than −10 to −5 mV, and multiple sperm entries were induced when the potential was held more negative. Based on this potential-dependent fertilization block mechanism, it was demonstrated that an activation potential (AVP) which is induced immediately after the attachment of the first sperm to the egg surface plays the role of a fast polyspermy block. The AVP-mediated polyspermy block mechanism develops as the oocyte matures and deteriorates as it ages. AVPs of mature oocytes exceeded −5 mV (the critical potential level for fertilization block) within 1 sec, and the potential stayed at +12 mV even after the initiation of fertilization membrane elevation. Consequently, the entry of a second sperm is prevented. In contrast, AVPs of overripe oocytes took about 15 sec to attain −5 mV, or they did not attain −5 mV at all. In overripe oocytes multiple sperm entries were associated with “step depolarization(s)” in the rising phase of the AVPs before membrane elevation took place. Immature oocytes generated AVPs associated with sperm entries, but without membrane elevation. AVPs in immature oocytes were characterized by the step depolarization(s) in the rising phase, and an AVP could be evoked again by a second insemination 20 min after the first insemination. These findings indicate that immature oocytes lack both fast and slow polyspermy block mechanisms.     

Biochemical studies on the mechanism of difference in the renal toxicity of 5-hydroxy-L-tryptophan between Sprague Dawley and Wistar rats.

The biochemical mechanisms of the renal toxicity of 5-hydroxy-L-tryptophan to rats were studied using Wistar and Sprague Dawley rats, which had different LD50 values. When the amino acid was injected intraperitoneally, Wistar rats, which had a low LD50 value of 5-hydroxy-L-tryptophan, excreted larger amonts of serotonin and smaller amounts of 5-hydroxyindole acetic acid into the urine than Spraque Dawley rats, which had a high LD50 value. The activity of renal aromatic L-amino acid decarboxylase was higher in Wistar rats than in Sprague Dawley rats, while the activity of renal aromatic amino acid transaminase was in an opposite relationship. The activity of renal monoamine oxidase was almost the same in both strains and the activity of renal UDP glucuronyltransferase in Wistar rats was higher than in Sprague Dawley rats. Since the renal damage caused in rats by 5-hydroxy-L-tryptophan was very similar to that caused by serotonin, the amine formed from the administered amino acid was thought to be an important factor for the renal necroses, and difference in serotonin formation from the administered precursor amino acid may be one of the important factors leading to the difference in LD50 values in the two strains of rats.