Isolation and antihypertensive effect of angiotensin I-converting enzyme (ACE) inhibitory peptides from spinach Rubisco

Four new inhibitory peptides for angiotensin I-converting enzyme (ACE), that is, MRWRD, MRW, LRIPVA, and IAYKPAG, were isolated from the pepsin-pancreatin digest of spinach Rubisco with the use of HPLC. IC(50) values of individual peptides were 2.1, 0.6, 0.38, and 4.2 microM, respectively. MRW and MRWRD had an antihypertensive effect after oral administration to spontaneously hypertensive rats. Maximal reduction occurred 2 h after oral administration of MRW, whereas MRWRD showed maximal decrease 4 h after oral administration at doses of 20 and 30 mg/kg, respectively. IAYKPAG also exerted antihypertensive activity after oral administration at the dose of 100 mg/kg, giving a maximum decrease 4 h after oral administration. IAYKP, IAY, and KP, the fragment peptides of IAYKPAG, also exerted antihypertensive activity. LRIPVA [corrected] did not show any antihypertensive effect at a dose of 100 mg/kg despite its potent ACE-inhibitory activity.     

Impact of short-term high-fat feeding on lipid droplet content in mouse oocytes

Mature mammalian oocytes contain lipid droplets (LDs), which are neutral lipid storage organelles critically important for energy metabolism. In mice, maternal obesity, induced by long-term (> 3 months) high-fat feeding, contributes to the accumulation of LDs in mature oocytes. However, few studies have investigated the influence of short-term high-fat feeding on LD content. In this study, we demonstrated that 3 weeks of high-fat feeding is sufficient to increase LD content and intracellular triacylglycerol levels. Using a two-step centrifugation technique to release LDs into the perivitelline space, we found that short-term high-fat feeding increased the level of LDs in MII oocytes and that 3 days of high-fat feeding were sufficient to increase efficiency of LD release. Collectively, our study suggests that short-term high fat feeding can have a higher impact on lipid metabolism during oocyte maturation.     

Comparative nephrotoxicity of Cisplatin and nedaplatin: mechanisms and histopathological characteristics

The antineoplastic platinum complexes cisplatin and its analogues are widely used in the chemotherapy of a variety of human malignancies, and are especially active against several types of cancers. Nedaplatin is a second-generation platinum complex with reduced nephrotoxicity. However, their use commonly causes nephrotoxicity due to a lack of tumor tissue selectivity. Several recent studies have provided significant insights into the molecular and histopathological events associated with nedaplatin nephrotoxicity. In this review, we summarize findings concerning the renal histopathology and molecular pathogenesis induced by antineoplastic platinum complexes, with a particular focus on the comparative nephrotoxicity of cisplatin and nedaplatin in rats.     

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

Measurements of gross NH ₄ ⁺ and NO ₃ ^? production in forest soils were conducted using the ¹⁵N pool dilution method. Mineral topsoils (0?C10?cm depth) were collected from four forests from northern to southern Japan with a natural climate gradient to elucidate the mechanisms regulating gross nitrification rates in forest soils. Additionally, we attempted to evaluate the relative importance of heterotrophic nitrification in gross total nitrification using acetylene as a specific inhibitor of autotrophic nitrification. Distinct differences were found among sites in the gross rates of NH ₄ ⁺ production (3.1?C11.4?mg?N?kg^?1?day^?1) and gross total nitrification (0.0?C6.1?mg?N?kg^?1?day^?1). The rates of gross heterotrophic nitrification were low in this study, indicating that heterotrophic nitrification is of minor importance in most forest mineral topsoils in Japan. Significant relations were found between gross autotrophic nitrification and gross NH ₄ ⁺ production, soil N, and soil C concentrations, but none was found between gross autotrophic nitrification and soil pH. We determined the critical value of the gross NH ₄ ⁺ production rates for gross autotrophic nitrification under which no gross autotrophic nitrification occurred, as well as the critical soil C/N ratio above which gross autotrophic nitrification ceased. Results show that tight coupling of production and consumption of NH ₄ ⁺ prevents autotrophic nitrifiers from utilizing NH ₄ ⁺ as long as NH ₄ ⁺ availability is low.     

Light-evoked changes in the interphotoreceptor matrix

The normal function of vertebrate photoreceptor cells depends on multiple interactions and transfer of substances between the photoreceptors and the retinal pigment epithelium (RPE), but the mechanisms of these interactions are poorly understood. Many are thought to be mediated by the interphotoreceptor matrix (IPM), a complex extracellular matrix that surrounds the photoreceptors and lies between them and the RPE. Histochemical, immunocytochemical, and lectin probes for several IPM constituents revealed that components of the IPM in the rat undergo a major shift in distribution or molecular conformation after the transition between light and dark. In the light, various IPM constituents concentrated in bands at the apical and basal regions of the outer segment zone; in the dark, they distributed much more uniformly throughout the zone. The change in IPM distribution was triggered by the light-dark transition; it was not a circadian event, and it was not driven by a systemic factor. The light-evoked change in IPM distribution may facilitate the transfer of substances between the photoreceptors and the RPE.     

Histopathological and Immunohistochemical Characterization of Spontaneously Occurring Uterine Deciduomas in Young Adult Rats

Uterine deciduomas were found in two female virgin rats, a 15-week-old Lewis rat and a 7-week-old Sprague-Dawley rat. The firm white nodules were located at the base of unilateral uterine horns and were approximately 6 mm and 4 mm in diameter. Histopathologically, the nodules were composed of three areas, each with a distinct type of proliferating cells: large epithelioid decidual cells with round nuclei, prominent nucleoli and abundant eosinophilic cytoplasm (antimesometrial region); compact spindle-shaped cells with oval nuclei and vacuolar cytoplasm (transitional region); and pleomorphic and spiny cells with round to oval nuclei and compact eosinophilic cytoplasm (mesometrial region). These cells proliferated in sheet-like arrangements and transformed into the other types of cells located in surrounding regions. Immunohistochemically, proliferating cells in all regions were strongly positive for proliferating cell nuclear antigen. The proliferating cells were positive for vimentin, and large decidual cells were positive for common acute lymphoblastic leukemia antigen 10, a marker of uterine interstitial cells. Large decidual cells were positive for α-smooth muscle actin and desmin, suggesting differentiation into muscular cells. Progesterone receptor was expressed in all cell types; however, estrogen receptor α was not expressed in the antimesometrial region. These extremely rare tumor-like nodules represent nonneoplastic lesions referred as decidual reactions of endometrial interstitial cells, and their biological behavior is that of a space-occupying benign tumor in young rats. Our cases might provide information as a historical control in toxicity and pharmacological studies in rats.     

Comparison of 3 different reinforcements of learning in dogs (Canis familiaris)

Effective dog training involves reinforcement of the dog's correct actions in response to specific cues given by the trainer. Food is usually selected as the primary reinforcer (reward), although this selection does not necessarily account for the learning preferences of individual dogs. We evaluated the relationship between reward and learning efficiency. Fifteen dogs were allocated to 3 different reward groups (food, stroking, and praise) and trained by an identical process. The food reward was the only one that shortened the time taken for the response to the command to be completed. However, this difference occurred only in the early training stages and not later in the training process.     

Anaphylaxis after rabies vaccination for dogs in Japan

Severe adverse reactions after rabies vaccination in dogs were examined from 317 cases reported to the Ministry of Agriculture, Forestry and Fisheries (MAFF) in Japan during 15-year period from April 2004 to March 2019. We found that 109 of the 317 dogs showed anaphylaxis (0.15/100,000 vaccinated dogs), and 71 of the 109 cases of anaphylaxis resulted in death (0.10/100,000 vaccinated dogs). We measured bovine serum albumin (BSA) in four commercially available rabies vaccines and found the levels ranged from 0.1 to 16.6 µg/dose. Our survey showed that the rate of anaphylaxis to rabies vaccines in dogs is rare, although some cases of anaphylaxis resulted in death. Veterinarians should be well prepared to deal with vaccine-associated anaphylaxis.     

Purification and Characterization of Cathepsin B from the Muscle of Horse Mackerel Trachurus japonicus

An endogenous protease in fish muscle, cathepsin B, was partially purified and characterized from horse mackerel meat. On SDS-PAGE of the purified enzyme under reducing conditions, main protein bands were detected at 28 and 6 kDa and their respective N-terminal sequences showed high homology to heavy and light chains of cathepsin B from other species. This suggested that horse mackerel cathepsin B formed two-chain forms, similar to mammalian cathepsin Bs. Optimum pH and temperature of the enzyme were 5.0 and 50 °C, respectively. A partial cDNA encoding the amino acid sequence of 215 residues for horse mackerel cathepsin B was obtained by RT-PCR and cloned. The deduced amino acid sequence contains a part of light and heavy chains of cathepsin B. The active sites and an N-glycosylation site were conserved across species. We also confirmed that the modori phenomenon was avoided by CA-074, a specific inhibitor for cathepsin B. Therefore, our results suggest that natural cysteine protease inhibitor(s), such as oryzacystatin derived from rice, can apply to thermal-gel processing of horse mackerel to avoid the modori phenomenon. Meanwhile, this endogenous protease may be used for food processing, such as weaning meal and food for the elderly.