Decreases of apolipoprotein B-100 and A-I concentrations and induction of haptoglobin and serum amyloid A in nonfed calves

Reduced feed intake near parturition is suggested to be one of the major causal factors for the development of fatty liver in cows, and nonfeeding has been used as an experimental model for fatty liver. In cows with fatty liver, concentrations of lipoprotein lipids and proteins are decreased. In addition, the acute-phase protein haptoglobin is induced. The purpose of the present study was to examine whether the decrease of lipoprotein concentrations and the induction of acute-phase proteins were similarly reproduced by non-feeding. Holstein female calves (n=5) were nonfed for 3 days and thereafter refed. Serum concentrations of nonesterified fatty acids and beta-hydroxybutyric acid were initially increased by the nonfeeding, and followed by decreases in concentrations of cholesteryl esters, phospholipids, apolipoprotein (apo) B-100 and apoA-I. The apoC-III concentration was not distinctly decreased. Haptoglobin and serum amyloid A were induced during the nonfeeding and refeeding process. Haptoglobin was distributed in different proportions in the high-density lipoprotein, very high-density lipoprotein and the lipoprotein-deficient fractions, whereas almost all serum amyloid A was associated with the high-density lipoprotein fraction. These results suggest that the decreases in lipoprotein concentrations and induction of acute-phase proteins found in cows with fatty liver and those with fatty liver-related diseases such as ketosis are primarily due to the reduced feed intake near parturition.     

Decreases in serum apolipoprotein B-100 and A-I concentrations in cows with milk fever and downer cows

Milk fever occurring during the peripartum period has been suggested to be caused by fatty liver developed during the nonlactating stage because diseased cows have increased serum concentrations of non-esterified fatty acids (NEFA) and show hepatic lipidosis. In cows with fatty liver and related diseases such as ketosis, serum concentrations of apolipoprotein (apo) B-100 and apoA-I are decreased. The purpose of the present study was to examine whether apoB-100 and apoA-I concentrations are similarly decreased in cows with milk fever. Apolipoprotein concentrations were also measured in cows with downer syndrome, which has been suggested to be related, at least in part, to milk fever. Compared with healthy cows during early lactation, apoB-100 and apoA-I concentrations were decreased in cows with milk fever and also in downer cows. In cows with milk fever, the decreases in apoB-100 and apoA-I concentrations were associated with increased NEFA and decreased cholesterol and phospholipid concentrations. However, in downer cows, serum lipid concentration changes were not as distinct as in cows with milk fever. These results, coupled with previous findings on the decreases in apoB-100 and apoA-I concentrations of cows with fatty liver-related diseases, suggest that fatty liver is involved in the development of milk fever and partly in that of downer cow syndrome.     

Inhibition by melittin of phosphorylation by protein kinase C of annexin I from cow mammary gland

Protein kinase C (PKC) is a phosphotransferase activated by diacylglycerols, phospholipids and Ca(2+), that regulates a wide variety of biological functions by phosphorylating multiple protein substrates such as annexin I. Annexin I is a phospholipid/Ca (2+)-binding protein distributed in various tissues, including the mammary gland, and is thought to mediate the anti-inflammatory actions of glucocorticoids by inhibiting phospholipase A(2). Melittin, a phospholipase A(2) activator in bee venom, is known to inhibit PKC activity when lysine-rich histone is used as the substrate. The purpose of the present study was to examine whether phosphorylation by PKC of annexin I from cow mammary gland was inhibited by melittin. Melittin inhibited annexin I phosphorylation by PKC in a dose-dependent manner, and its IC(50) value (concentration causing 50% inhibition) was 0.8 microM. The phosphorylation of annexin I was also inhibited by the amphiphilic polypeptides mastoparan and polymyxin B, and their inhibitory effects were comparable to that of melittin. The surface-inactive polypeptide bacitracin was less effective. The inhibition by melittin was effectively reversed by the excess addition of phosphatidylserine, but not distinctly by 1-oleoyl-2-acetyl-sn-glycerol or Ca(2+), suggesting that melittin inhibited the phosphorylation of annexin I by interacting with phosphatidylserine. The inhibition by melittin of PKC phosphorylation of annexin I seems to be pathophysiologically important, because a melittin-like phospholipase A(2)-stimulatory protein is present in bovine endothelial cells.     

New race of <Emphasis Type="Italic">Phytophthora vignae</Emphasis> f. sp. <Emphasis Type="Italic">adzukicola</Emphasis>, the causal agent of Phytophthora stem rot of the adzuki bean

 A new race of Phytophthora vignae f. sp. adzukicola, designated race 4, is reported from central and western Hokkaido, Japan. The isolates obtained from diseased plants of a new cultivar, cv. Syumari, which is resistant to races 1, 2, and 3, were determined to be a new race by the pathogenic reaction on a set of differential adzuki bean cultivars (cv. Erimo-shozu, cv. Kotobuki-shozu, cv. Noto-shozu, cv. Urasa-shimane, and cv. Syumari). Received: March 7, 2002 / Accepted: August 13, 2002     

Seasonal variation of paulownia witches’-broom phytoplasma in paulownia trees and distribution of the disease in the Tohoku district of Japan

Seasonal variation of paulownia witches’-broom (PWB) phytoplasma within different organs (leaves, branch and trunk bark and roots) in paulownia trees was investigated by the amplification of a PWB-specific DNA fragment by the polymerase chain reaction (PCR). In leaf samples, PWB phytoplasma was first detected in June and the incidence gradually increased. On the other hand, the PWB was detected at relatively low incidence in branch bark, trunk bark and roots and the incidence did not change among seasons. A survey of PWB in 27 fields in the Tohoku district of Japan showed that malformed flower buds were observed in paulownia trees in almost all of the fields. PWB-phytoplasma was also detected by PCR from paulownia trees in almost all of the fields in Iwate and Fukushima Prefectures. The frequencies of trees in which phytoplasma was detected by PCR were higher than those in which symptoms were observed. These results indicated that PCR amplification of a PWB-specific DNA fragment is an effective tool for practical diagnose and that PWB is widely distributed in the Tohoku district of Japan.     

Transcatheter closure of congenital ventricular septal defects in 3 dogs with a detachable coil

The purpose of this study was to evaluate the feasibility, safety, and efficacy of transcatheter closure in dogs with a congenital perimembranous ventricular septal defect (VSD) by using a detachable coil. No dogs showed any symptoms, and results of chest X-rays and ECGs were normal. The diameters of VSD ranged from 2 to 4 mm on echocardiogram. The defect was 2-2.5 mm from the aortic valve. A detachable coil (size 5 mm with 5 loops) designed for patent ductus arteriosus was delivered via the transarterial route. The device was successfully employed in all dogs. A minimal residual shunt was observed in all dogs even though Qp/Qs decreased. Hemolysis and a rate-dependent right-bundle branch block were observed in 1 dog, but there was no clinical significance. No major complication was noted. Pathologic examination after 1 year revealed that the coils were covered with tissue without significant damage to the His-Purkinje conduction system. In conclusion, transcatheter closure of a small perimembranous VSD with a detachable coil can be achieved without major complications or significant pathologic damage at the lesion site.     

Modulation by sphingosine of phosphorylation of substrate proteins by protein kinase C in nuclei from cow mammary gland

Protein kinase C (PKC) is an enzyme activated by diacylglycerols such as 1-oleoyl-2-acetyl-sn-glycerol (OAG), phospholipids (in particular phosphatidylserine; PS) and Ca2+, which regulate a wide variety of intracellular functions by phosphorylating multiple substrate proteins and enzymes. The effect of sphingosine, the backbone moiety of sphingolipids, on PKC activity and phosphorylation of endogenous proteins catalyzed by PKC was investigated in nuclei of cow mammary gland. Sphingosine inhibited nuclear PKC activity when lysine-rich histone was used as the substrate. The sphingosine inhibition of the PKC activity was reversed by the excess addition of PS, but not by OAG or Ca2+. Several nuclear proteins, including 56-kDa, 43-kDa, 38-kDa and 36-kDa proteins, were shown to be substrates for PKC. Of the substrate proteins, the 38-kDa and 36-kDa proteins were identified as annexin I, the Ca2+/phospholipid-binding protein; the 56-kDa and 43-kDa proteins have not yet been identified. Sphingosine inhibited phosphorylation of the 56-kDa protein and the 36-kDa annexin I, whereas it enhanced that of the 43-kDa protein. The 38-kDa annexin I species was unaffected by sphingosine. As with the PKC activity, inhibition by sphingosine of phosphorylation of the 56-kDa protein and 36-kDa annexin I was reversed by the excess addition of PS, but not by OAG or Ca2+. In addition, by the excess addition of PS and not by OAG or Ca2+, the sphingosine-enhanced phosphorylation of the 43-kDa protein was reversed and returned to near the level in the absence of sphingosine. It is suggested that sphingosine is involved in the regulation of PKC-dependent phosphorylation in the nucleus by modulating the association of PKC or its substrates, particularly annexin I, with membrane phospholipids in cow mammary gland.     

Changes in vitamin A added to a fermented total mixed ration prepared with reed canarygrass (Phalaris arundinacea L.)

A fermented total mixed ration (TMR) was prepared by adding a vitamin premix containing vitamin A and enzyme to reed canarygrass roughage. The vitamin A levels were then determined after 30 days of fermentation at 20 or 30°C. The vitamin A contents had decreased in roughage fermented at both storage temperatures, and decreased further when an enzyme supplement was included. Because the majority of the added vitamin A was destroyed during fermentation and storage, the addition of vitamin A at the beginning of preparation of fermented TMR is not recommended.     

Nitrate Loss for Denitrification during High Frequency Research in Floodplain Groundwater of the Tama River

This study aims to identify the possible roles of a floodplain inbiogeochemical nitrogen cycles, based on analysis of groundwaterdynamics of inorganic nitrogen species. Groundwater samples collected from boreholes made of poly vinyl chloride located onthe floodplain in the middle reach of the Tama River, Nagata district were analyzed for dissolved organic carbon, dissolved oxygen, inorganic nitrogen compounds, major anions and the stableisotope ratio of nitrate-nitrogen.Dissolved oxygen in groundwater samples collected from marked borehole (G-5) was low (50 ± 16 μM) and nitrate decreasedfrom 63 μM to < 10 μM during our research period. Concentrations of nitrate, nitrite and nitrous oxide decreased one after the other. These decreases in concentration, combinedwith ¹⁵N-enrichment of groundwater nitrate suggest denitrification as a significant nitrate sink, yielding an isotopic fractionation of nitrate-nitrogen with an enrichment factor (ε= –17.9‰) that is comparable tothose in various soil and groundwater systems. This study provesthat floodplains can perform as nitrogen sinks for groundwaterin river catchments.