Masatoshi Ichida

Mulberry leaf extract prevents amyloid beta-peptide fibril formation and neurotoxicity

Mulberry leaf has been reported to possess medicinal properties, including hypoglycemic, hypotensive and diuretic effects. Little is known, however, about its medicinal properties for central nervous system disorders, including Alzheimers disease. Accumulating evidence suggests that amyloid &bgr;-peptide (1–42) plays an important role in the etiology of Alzheimers disease. Here we show that mulberry leaf extract inhibits the amyloid &bgr;-peptide (1–42) fibril formation by both the thioflavin T fluorescence assay and atomic force microscopy. Furthermore, mulberry leaf extract protected hippocampal neurons against amyloid &bgr;-peptide (1–42)-induced cell death in a concentration-dependent manner. These results suggest that mulberry leaf extract provides a viable treatment for Alzheimers disease through the inhibition of amyloid &bgr;-peptide (1–42) fibril formation and attenuation of amyloid &bgr;-peptide (1–42)-induced neurotoxicity.

Structure and Chemical Composition of Silk Proteins in Relation to Silkworm Diet

We investigate the structure and chemical composition of silk proteins produced by silkworms reared entirely on an artificial (A) diet, and compared those with worms entirely on a mulberry leaf ( M ) diet. The artificial diet has tofu-cake as its main component. Two types of cocoons (A and M) are used as sample materials. The dissolution behavior of the A sericin in hot water is different from that of M sericin; the amount of A sericin dissolved (28%) is higher than that of M (24%), and the dissolution rate of A sericin is also higher. Both sericins are separated into four fractions according to dissolution rate in hot water, and the amino acid composition (AAC) of each fraction is determined. Although the AAC of unfractionated A sericin is almost the same as that of M sericin, the AACs of the fractionated sericin from the A sample are distinguished from those from the M sample. AACs of the A and M fibroins are also evaluated and found to be almost identical within experimental error. The x-ray diffraction pattern of the A fibroin is also nearly the same as that of M fibroin. The artificial diet used in this study affects the dissolution behavior and chemical com position of sericin proteins, but does not affect structure and chemical composition of fibroin proteins.

Developmental changes in urea in the haemolymph (determined by a urease-indophenol method) in hybrid strains of the silkworm, Bombyx mori and the effect of starvation in the fifth instar larvae, fed an artificial diet, on urea level in subsequent development

Abstract 1. 1. Developmental changes in urea in the haemolymph in hybrid strains of the silkworm, Bombyx mori were determined by a urease-indophenol method in silkworms fed an artificial diet or fed fresh mulberry leaves. 2. 2. Lower concentrations of urea in the haemolymph compared to our previous results determined by a chemical method (Suraida et al., 1990; Comp. Biochem. Physiol. 97A, 373–379) were observed in the fourth and fifth larval instars, approximately 0.1–0.2 and 0–0.05 mg urea N/ml haemolymph in the silkworms fed an artificial diet and fed fresh mulberry leaves, respectively. 3. 3. Concentrations of urea in the haemolymph in pharate adults, approximately 0.7–0.8 and 0.001 mg urea N/ml haemolymph in the silkworms fed an artificial diet and fed fresh mulberry leaves, were similar to our previous results. 4. 4. Based on evaluation of the assay method, it was concluded that the changes in urea in the haemolymph in a hybrid strain of the silkworm, Bombyx mori in the larval stage was established for the first time in the present study. 5. 5. Starvation from 72 hr after the fourth larval-larval ecdysis in the silkworms fed an artificial diet resulted in a further elevated concentration of urea, approximately 1 mg urea N/ml haemolymph in the pharate adult stage, a 20% increase against non-starved control silkworms.

Identification of an antiamyloidogenic substance from mulberry leaves.

Fibrillar aggregates of amyloid &bgr;-peptides are major constituents of the plaques found in the brains of patients with Alzheimers disease, and have been implicated in the neurotoxicity of Alzheimers. We previously reported that the methanol extract of mulberry leaves inhibits the formation of amyloid &bgr;-peptide (1-42)-fibrils in vitro, and protects hippocampal neurons from amyloid &bgr;-peptide (1-42)-induced cell death. In this study, we identified antiamyloidogenic substances, pheophorbide a, kaempferol -3-O-glucoside, and kaempferol -3-O-(6-malonyl) glucoside, from the methanol extract of mulberry leaves. We also compared the antiamyloidogenic activity of pheophorbide a with that of other porphyrin-related compounds.

Azimuth characteristics of radio wave propagation in a mulberry farm in 920-MHz band

Data collection of the radio wave propagation loss in farm fields is valuable to design a wireless network in a farm. They are used in calculating the link budget to establish a proper and efficient node arrangement. In this study, propagation losses in a 50 × 50 m mulberry field were measured in 920-MHz band with respect to the azimuthal angle of the propagation direction to arrays of bushes. Received signal strength indicators (RSSIs) were measured and they were converted to the path loss. Antennas were placed at a height of 1.5 m while the height of the bush was 3.5 m. Moreover, horizontal and vertical polarizations were measured. The results revealed that the horizontal polarization could be less affected by the direction angle to the ridges than the vertical polarization. These data would be useful for the evaluation of link budgets to design wireless networks in a farm.

Effect of vegetation on radio wave propagation in 920-MHz and 2.4-GHz bands

Collecting data of propagation losses in farm fields is important to design a wireless network in a farm. They are used in calculating the link budget to establish a proper and efficient node arrangement. In this study, propagation losses in a 50 × 50 m mulberry field were measured in 920-MHz and 2.4-GHz bands. Received signal strength indicators (RSSIs) were measured as a function of the distance and the angle between the propagation direction and the ridges (bush arrays). The data were converted to the vegetation attenuations and the propagation characteristics were compared in both bands. The antennas were placed at a height of 1.5 m. The height of the bush was 1.5 – 3.5 m. Moreover, the horizontal and vertical polarizations were measured and the differences were shown.

The effect of bush growth on radio wave propagation in 920-MHz band

The change of the radio wave propagation loss in 920-MHz band was examined as bushes in a farm grew higher. Received Signal Strength Indicator (RSSI) was measured as a function of the distance between the transmitting antenna (Tx) and the receiving antenna (Rx) in a 50 × 50 m mulberry field. Tx and Rx were placed at a height of 1.5 m. Moreover, the horizontal and vertical polarizations were measured. The results revealed that the path loss increased in both horizontal and vertical polarizations as bushes grew up and that the horizontal polarization could be less affected by bushes than the vertical polarization.