Experimental infection of pigs with different doses of the African swine fever virus Armenia 07 strain by intramuscular injection and direct contact

We experimentally infected pigs with the African swine fever virus (ASFV) Armenia 07 strain (genotype II) to analyze the effect of different dose injections on clinical manifestations, virus-shedding patterns, histopathology, and transmission dynamics by direct contact. Each three pigs and four pigs were injected intramuscularly with 0.1 fifty percent hemadsorbing doses (HAD₅₀)/ml, 10¹ HAD₅₀/ml and 10⁶ HAD₅₀/ml of ASFV Armenia 07 strain, respectively. Each two of three pigs injected with 0.1 HAD₅₀/ml and 10¹ HAD₅₀/ml died by 10 days post inoculation. All pigs had a gross lesion of splenomegaly. Perigastric and renal lymph nodes were enlarged and resembled blood clots in nine of ten pigs. It was revealed that 0.1 HAD₅₀/ml of this ASFV was sufficient to infect healthy pigs by intramuscular injection and caused sub-acute lethal disease. For the transmission study, two 8-week-old pigs were injected intramuscularly with 10³ HAD₅₀/ml of the same virus. Each of the experimentally inoculated pigs was co-housed with two 8-week-old naive pigs. All contact pigs exhibited clinical manifestations at 6 or 7 days after the experimentally inoculated pigs developed pyrexia. These findings suggest that this strain may spread slowly within a herd. Histologically, lymph nodes resembled blood clots were formed by severe blood absorption and followed hemorrhage result of disruption of the lymphoid sinus filling with absorbed red blood cells. The severity of the gross and histological lesions depended on duration after infection, regardless of the difference of injection doses in this study.     

The effects of concentrations of lysine in media on differentiation of 3T3‐L1 preadipocytes

Intramuscular fat content is increased by feeding of low lysine diets in pigs. Reduction in dietary lysine intake results in low plasma lysine concentration and low cytosolic lysine concentration in skeletal muscles. From these observations, we hypothesized that low plasma lysine concentration in pigs fed on low lysine diets reduced supply of lysine from blood circulation to preadipocytes, and this limited supply of lysine might promote adipocyte differentiation in porcine muscles. In order to verify the hypothesis, we investigated the effects of low concentrations of lysine in culture medium on differentiation of 3T3‐L1 preadipocytes. Low concentration of lysine suppressed lipid accumulation and messenger RNA (mRNA) expression and enzyme activity of fatty acid synthase. mRNA expressions of peroxisome proliferator‐activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) were lower in cells cultured in low lysine medium. On the other hand, mRNA and protein expressions of C/EBPβ and C/EBPδ were not inhibited by low concentrations of lysine in culture medium. These results indicate that low lysine concentrations in culture medium inhibit differentiation of 3T3‐L1 preadipocytes through inhibiting the mRNA expressions of PPARγ and C/EBPα.     

Myosin denaturation in heated myofibrils of scallop adductor muscle

The thermal inactivation of Ca²⁺ ATPase of scallop myofibrils (0.1 M KCl, pH 7.5) was found to be unaffected by the presence of Ca²⁺. Monomeric myosin content and salt solubility decreased much faster than Ca²⁺ ATPase inactivation in both Ca and EDTA media, which was well explained by faster denaturation of the rod portion than subfragment-1 of myosin. In contrast, when the myofibrils were heated at 0.5 M KCl, a slow decrease in salt solubility was observed, which was also explained by slow denaturation of the rod portion of myosin. Myofibrils from scallop smooth muscle showed the same denaturation pattern as those from adductor muscle. These results show that mollusk myosin is not always stabilized by Ca²⁺.     

A new behavioral test for detecting decline of age-related cognitive ability in dogs

A simple test for detecting decline of cognitive ability in aged dogs is needed in modern society. We used a basic place-selection test to develop a new test to assess cognitive ability in dogs, using 25 house dogs. Three covered bowls were placed in front of the subject. One of them was the correct bowl, from which the subject was rewarded with a food treat when he/she chose it. If the subject made an incorrect selection, he/she was returned to the starting point and the trial was repeated. Cognitive ability was assessed by the number of errors needed to fulfill the criterion. We found a significantly high correlation between the dogs’ ages and the number of error trials, suggesting that age-related cognitive dysfunction may reliably be assessed by the documented place-learning test.     

Effect of long-term administration of a prostacyclin analogue (beraprost sodium) on myocardial fibrosis in Dahl rats

Beraprost sodium (BPS) is an orally active prostacyclin analogue. The effects of BPS on the heart, including coronary circulation improvement, myocardial and vascular protection and anti-fibrosis effect on myocardium interstitium, have previously been demonstrated. However, the effects of BPS on hemodynamics, cardiac function and myocardial contractility in patients in the hypertrophic phase have not been clarified. Therefore, in the present study, the effects of BPS under long-term administration were investigated using the hypertension model of salt-sensitive Dahl rats. Six-week-old Dahl rats were divided into three groups, an 8% high salt diet group treated with BPS (BPS group), an untreated 8% high salt diet group (HHF group) and an untreated 0.3% low salt diet group (Control group), and observations were conducted until 17 weeks of age. In the BPS and HHF groups, the survival rates after 11 weeks of high salt diet intake were 87.5% and 47.1%, respectively (p<0.05). At 17 weeks of age, the atrial systolic peak velocity/early diastolic peak velocity and heart weight index of the BPS group decreased significantly compared with the HHF group (p<0.05). The HHF group exhibited significantly more severe myocardial fibrosis mainly in the endocardial layer of the left and right ventricles compared with the BPS and Control groups (p<0.05). In the present study, long-term BPS administration preserved diastolic function and prevented myocardial interstitial fibrosis in the non-compensatory phase. The results of the present study suggest that BPS is effective for treatment of hypertensive cardiac hypertrophy.     

Comparison of physicochemical properties of 7S and 11S globulins from pea, fava bean, cowpea, and French bean with those of soybean--French bean 7S globulin exhibits excellent properties

Legume seeds contain 7S and/or 11S globulins as major storage proteins. The amino acid sequences of them from many legumes are similar to each other in the species but different from each other, meaning that some of these proteins from some crops exhibit excellent functional properties. To demonstrate this, we compared protein chemical and functional properties (thermal stability, surface hydrophobicity, solubility as a function of pH, and emulsifying properties) of these proteins from pea, fava bean, cowpea, and French bean with those of soybean as a control at the same conditions. The comparison clearly indicated that the 7S globulin of French bean exhibited excellent solubility (100%) at pH 4.2-7.0 even at a low ionic strength condition (mu = 0.08) and excellent emulsion stability (a little phase separation after 3 days) at pH 7.6 and mu = 0.08, although the emulsions from most of the other proteins separated in 1 h. These results indicate that our assumption is correct.     

The pain-relieving effects of lactoferrin on oxaliplatin-induced neuropathic pain

Oxaliplatin (OXL) therapy often causes side effects including chronic peripheral neuropathy. We investigated the pain-relieving effects of recombinant human lactoferrin (rhLf) as well as a long-acting IgG-Fc fused rhLf (rhLf-Fc) on OXL-induced neuropathic pain. We used the hLf in this study, because the homology between mouse Lf and hLf is higher than that of bovine Lf. In addition, rhLf-Fc is expected to enhance the analgesic effect due to the life extension effect in the body. We administered OXL (2 mg/kg, i.v.) to mice twice weekly for 4 weeks. Phosphate buffered saline (PBS), rhLf (100 mg/kg, i.p.) or rhLf-Fc (100 mg/kg, i.p.) was administered once a week from day 15 to 32. We also assessed the continuous infusion of same drugs (10 mg/kg/day) into the external jugular vein by using an osmotic pump. Both of rhLf and rhLf-Fc significantly reduced the hypersensitivity to mechanical stimulation when they were administered intraperitoneally. The continuous infusion of rhLf resulted in a more pronounced effect. Histopathological analysis of sciatic nerve showed that both rhLf and rhLf-Fc tended to reduce nerve fiber damage, but no significant difference was observed in nerve fiber cross-sectional area. Therefore, it was suggested that rhLf or rhLf-Fc injection could be an option for controlling neuropathic pain, which are side effects of OXL.     

Effects of dietary lysine levels and lighting conditions on intramuscular fat accumulation in growing pigs

This study was conducted to test our hypothesis that intramuscular fat (IMF) accumulation increases in pigs fed on a low lysine diet during the dark period than those fed on the same diet during the light period. Using barrows aged 6 weeks, we monitored whether serum glucose and insulin levels were affected by light conditions. Two diets with different levels of lysine, 0.78% (LL diet) and 1.37% (control diet) were prepared. Eight pigs were fed on the diet during the light period, while the remaining pigs were fed during the dark period. The pigs were fed either the LL diet or the control diet. Although IMF contents of Longissimus dorsi (LD) muscle were higher in the pigs fed on a LL diet (p < .05), the light conditions had no effect. Low dietary lysine caused reduction in serum glucose levels (p < .05) and serum insulin levels (p = .0613). However, they were also unaffected by the lighting conditions. To gain further insights, we determined the messenger RNA levels of insulin receptor, insulin receptor substrate 1, acetyl CoA carboxylase, and fatty acid synthase in LD and Rhomboideus muscles and in the liver.     

Further epidemiological survey for atovaquone resistant related gene of Babesia gibsoni in Japan during 2015–2018

A single-nucleotide polymorphism causing the replacement of methionine with isoleucine (M121I) in cytochrome b of Babesia gibsoni has been reported to reduce the susceptibility to atovaquone (ATV) in B. gibsoni infection. In our previous study, B. gibsoni with M121I was suggested to exist in nature. Thus, further examinations were performed. In total, 105 genomic DNA samples from B. gibsoni-infected dogs were collected from western (98 samples from 15 prefectures) and eastern areas (7 samples from 4 prefectures) in Japan. The M121I variant population was identified using allele-specific real-time PCR: it was then detected in nine samples (8.57%), which was higher than that in the previous study (4.11%). Although there are unclear points, such as the history of ATV usage, careful attention should be given to emerging ATV resistance.