SummaryMany plants contain latex that exudes when leaves are damaged, and a number of proteins and enzymes have been found in it. The roles of those latex proteins and enzymes are as yet poorly understood. We found that papain, a cysteine protease in latex of the Papaya tree (Carica papaya, Caricaceae), is a crucial factor in the defense of the papaya tree against lepidopteran larvae such as oligophagous Samia ricini (Saturniidae) and two notorious polyphagous pests, Mamestra brassicae (Noctuidae) and Spodoptera litura (Noctuidae). Leaves of a number of laticiferous plants, including papaya and a wild ®g, Ficus virgata (Moraceae), showed strong toxicity and growth inhibition against lepidopteran larvae, though no apparent toxic factors from these species have been reported. When the latex was washed off, the leaves of these lactiferous plants lost toxicity. Latexes of both papaya and the wild ®g were rich in cysteine-protease activity. E-64, a cysteine protease-speci®c inhibitor, completely deprived the leaves of toxicity when painted on the surface of papaya and ®g leaves. Cysteine proteases, such as papain, ®cin, and bromelain, all showed toxicity. The results suggest that plant latex and the proteins in it, cysteine proteases in particular, provide plants with a general defense mechanism against herbivorous insects.

Since ancient times, mulberry leaves (Morus spp.) have been used to rear the silkworm Bombyx mori. Because the silkworm grows well on mulberry leaves, the toxicities and defensive activities of these leaves against herbivorous insects have been overlooked. Here we show that mulberry leaves are highly toxic to caterpillars other than the silkworm B. mori, because of the ingredients of the latex, a milky sap exuded from mulberry leaf veins. The toxicity of mulberry leaves was lost when the latex was eliminated from the leaves, and artificial diets containing latex showed toxicity. Mulberry latex contained very high concentrations of alkaloidal sugar-mimic glycosidase inhibitors reported to have antidiabetic activities, such as 1,4-dideoxy-1,4-imino-D-arabinitol, 1-deoxynojirimycin, and 1,4-dideoxy-1,4-imino-D-ribitol. The overall concentrations of these inhibitors in latex reached 1.5-2.5% (8 -18% dry weight) in several mulberry varieties, which were Ϸ100 times the concentrations previously reported from whole mulberry leaves. These sugar-mimic alkaloids were toxic to caterpillars but not to the silkworm B. mori, indicating that the silkworm can circumvent the mulberry tree's defense. Our results suggest that latex ingredients play key roles in defense of this tree and of other plants against insect herbivory, and they imply that plant latexes are treasuries of bioactive substances useful as medicines and pesticides.plant defense ͉ plant-insect interactions ͉ Morus spp. ͉ Eri silkworm ͉ Bombyx mori

No abstract

No abstract

No abstract

The purpose of this investigation was to determine the effects of fat content and frequency of meals on the oral bioavailability of menatetrenone (2-methyl-3-all-trans-tetraprenyl-1,4-naphthoquinone), a vitamin K2 with four isoprene units. In the first series of studies, menatetrenone (15 mg) was administered at breakfast time to 18 healthy male volunteers after meals with three different fat contents (meals A, B, and C) on three occasions in a crossover design. The three types of meals had almost the same calorie content (721-746 kcal) with varied fat contents (A, 8.8 g; B, 20.0 g; C, 34.9 g). The area under the plasma menatetrenone concentration-time curve within the first 24 h (AUC0-24) increased with increase of fat content: 371 +/- 194, 485 +/- 150, and 1024 +/- 341 ng.h/mL (mean +/- SD, n = 18) after meals A, B, and C, respectively. On the fourth occasion, the same dose of menatetrenone was administered to all volunteers after taking meal B, but in this case the lunch 5 h after drug administration was omitted from the protocol. The time profile of plasma menatetrenone showed a single peak when lunch was not taken, whereas it showed two peaks with lunch. On the fifth occasion, 12 out of 18 volunteers took the same dose of menatetrenone after a meal with the highest fat content (53.8 g of fat and 789 kcal; meal D), showing that AUC0-24 was almost the same as that for meal C, 1027 +/- 389 and 991 +/- 392 ng.h/mL (n = 12) for meals C and D, respectively. The oral bioavailability of lipid-soluble vitamin K was influenced by the fat content of a meal, although the increase in bioavailability seemed to reach a peak when the lipid content of the meal was > 35 g.

No abstract

Cardiac dendritic cells are considered to play an important role in the immunoresponse of the heart. However, it is unclear whether these cells occur in human myocarditis and whether they function in similar ways to those in rats. Cardiac samples were obtained from 22 autopsied patients with myocarditis, and compared with 20 age-and sex-matched controls. Formalin-fixed hearts were immunostained by the LSAB method. Cardiac dendritic cells were detectable even in the control hearts (1.5 cells/high power field (HPF)). In the acute phase of myocarditis, the number of cardiac dendritic cells increased up to 12.6 cells/HPF (p<0.001). In the subacute phase of myocarditis, T cells (36.6 cells/HPF) and HLA-DR+ cells (10.2 cells/HPF) continued to infiltrate the periphery of the inflammatory lesions, but they had no expression without inflammation. In this study, cardiac dendritic cells were reactive for HLA-DR, but negative for CD68, and were characteristically large monocytes with long, slender, dendritic processes. Accordingly, they were clearly distinguishable from macrophages. In the human heart, cardiac dendritic cells may be recruited in the acute phase of myocarditis, and seem to play an important role in the succeeding immunoresponse.