Induction of chemoresistance in a cultured canine cell line by retroviral transduction of the canine multidrug resistance 1 gene

OBJECTIVE: To induce chemoresistance in a normal canine cell line through the transduction of the canine multidrug resistance 1 gene (mdr1). SAMPLE POPULATION: Madin-Darby canine kidney (MDCK) epithelial cell line. PROCEDURES: The full-length canine mdr1 cDNA clone isolated in our laboratory was inserted into a Moloney murine leukemia virus-based vector to construct the retroviral vector, pLNC-cMDR1. After retroviral transduction of pLNC-cMDR1 into MDCK cells, the expression and function of the P-glycoprotein, a product of mdr1, were assessed by immunoblotting, measurement of rhodamine123 (Rh123) retention, and drug sensitivity assays. RESULTS: P-glycoprotein was strongly expressed in cells transduced with pLNC-cMDR1. This P-glycoprotein was fully functional, as demonstrated by the decreased Rh123 retention and the increased resistance to chemotherapeutic drugs. Measured as 50% inhibitory concentrations, resistance increased 59 times to vincristine and 25 times to doxorubicin in MDCK cells after transduction of pLNC-cMDR1. CONCLUSIONS AND CLINICAL RELEVANCE: Transduction of canine mdr1 is an effective method for inducing chemoresistance in normal canine cells. This system may be applicable to the induction of drug resistance in hematopoietic cells.     

Effects of age,sex, and breed on the composition of free extractable ceramides in the stratum corneum of healthy dogs

Veterinary Research Communications - Ceramide (CER), an important component of the extracellular lamellar lipids in the stratum corneum (SC), plays a critical role in maintaining the cutaneous...     

Spontaneous adenolipoma of the mammary gland in the male F344 rat

A 110-week-old male F344 rat from the high-dose group of a 104-week carcinogenicity study, exhibited a spontaneously occurring subcutaneous mass in the left axilla extending to the chest. Histologically, the mass was well-demarcated from the adjacent mammary tissue and slightly encapsulated without evidence of infiltration into the surrounding tissues. The mass contained both epithelial and adipose components. The epithelial component consisted of ductal structures of various sizes lined by a single layer of flattened to cuboidal epithelial cells with relatively clear or vacuolated cytoplasm. These ductal structures were well-intermingled with an adipose component that consisted of a uniform monomorphic cell population of mature adipocytes. Both cell types were well-differentiated and did not exhibit cellular atypia. Within the mass, fibrous connective tissue was found in the stroma with infiltration of numerous mast cells. Based on these findings, the mass was diagnosed as an adenolipoma of the mammary gland.     

Multi‐system progressive angiomatosis in a dog resembling blue rubber bleb nevus syndrome in humans

A six‐year‐old, neutered, female golden retriever was presented with generalised, dark purple to black cutaneous nodules and gastrointestinal haemorrhage. Histopathologically, all cutaneous nodules were diagnosed as benign cavernous haemangiomas. Endoscopic analysis revealed similar nodules in the oesophagus, stomach and duodenum. At laparotomy, similar nodules were seen on the visceral peritoneal lining of abdominal organs. Metastatic haemangiosarcoma was ruled out based on histological features and lack of primary tumour in spleen, liver or heart ultrasonographically. Blood loss associated with gastrointestinal haemorrhage was managed with blood transfusion. To the authors’ knowledge, this is the first canine case of multi‐system progressive angiomatosis resembling blue rubber bleb nevus syndrome in humans.     

Sooty spot caused by Cladosporium cladosporioides in postharvest Satsuma mandarin grown in heated greenhouses

In June 2006, a large number of small black spots containing a branching network of black hyphae developed on shipped Satsuma mandarin fruits grown in greenhouses, which markedly decreased their commercial value. The fungus that was frequently isolated from the damaged fruits was identified as Cladosporium cladosporioides. Inoculation of fruits with the fungus caused the same symptoms, and the fungus was reisolated from the diseased fruits. The disease caused by this fungus has not been previously documented in citrus fruits; we name this new disease “sooty spot” on the basis of its symptoms.     

Tomatidine, a tomato sapogenol, ameliorates hyperlipidemia and atherosclerosis in apoE-deficient mice by inhibiting acyl-CoA:cholesterol acyl-transferase (ACAT)

It was previously revealed that esculeoside A, a new glycoalkaloid, and esculeogenin A, a new aglycon of esculeoside A, contained in ripe tomato ameliorate atherosclerosis in apoE-deficent mice. This study examined whether tomatidine, the aglycone of tomatine, which is a major tomato glycoalkaloid, also shows similar inhibitory effects on cholesterol ester (CE) accumulation in human monocyte-derived macrophages (HMDM) and atherogenesis in apoE-deficient mice. Tomatidine significantly inhibited the CE accumulation induced by acetylated LDL in HMDM in a dose-dependent manner. Tomatidine also inhibited CE formation in Chinese hamster ovary cells overexpressing acyl-CoA:cholesterol acyl-transferase (ACAT)-1 or ACAT-2, suggesting that tomatidine suppresses both ACAT-1 and ACAT-2 activities. Furthermore, the oral administration of tomatidine to apoE-deficient mice significantly reduced levels of serum cholesterol, LDL-cholesterol, and areas of atherosclerotic lesions. The study provides the first evidence that tomatidine significantly suppresses the activity of ACAT and leads to reduction of atherogenesis.     

Partial cDNA sequence of a relaxin‐like factor (RLF) receptor,LGR8 and possible existence of the RLF ligand‐receptor system in goat testes

Relaxin‐like factor (RLF), also known as insulin‐like factor 3 (INSL3), is produced by testicular Leydig cells, but its specific receptor LGR8 (leucine‐rich repeat family of G‐protein‐coupled receptor 8) has not been identified in goats. This study aimed to identify complementary DNA (cDNA) sequences of goat LGR8, and characterize the expression of both RLF and LGR8 in goat testes by RT‐PCR and immunohistochemistry. Testes were collected from immature (3‐month‐old) and mature (24‐month‐old) Saanen goats, and partial cDNA sequences of the goat homologue of human LGR8 were identified. The sequence encoded a reduced peptide sequence of 167 amino acids, which corresponded to transmembrane regions 2 through 5, followed by the beginning of intracellular loop 3 of human LGR8. Expression of both LGR8 and RLF genes was drastically increased in mature testes compared with immature ones. Although RLF protein was restricted to Leydig cells, LGR8 protein was detected in both Leydig cells and seminiferous epithelial cells (possibly germ cells and Sertoli cells). These results reveal a possible existence of the RLF‐LGR8 ligand‐receptor system within the goat testis, suggesting that RLF may play a role in testicular function through LGR8 on Leydig cells and seminiferous epithelial cells in an autocrine and/or paracrine manner.     

Cultural control of leafhopper-induced maize wallaby ear symptom in forage maize via early planting dates

Maize wallaby ear symptom (MWES) is induced by maize orange leafhopper (Cicadulina bipunctata) feeding and stunts the growth of maize. We examined the relationship between maize developmental stage and MWES occurrence and the effect of planting date on injury from MWES in western Japan. MWES was more pronounced on young maize, and rarely observed on maize older than the 5th or 6th leaf stage, indicating that younger maize is more susceptible to MWES. In a field experiment, early planting (before late July) avoided MWES and resulted in higher yields of forage maize, whereas MWES occurrence and yield loss gradually increased with late planting (from early to middle August) because of a rapid increase in C. bipunctata density during this period. Leaf and stem dry matter of the MWES-susceptible maize variety “3470” decreased together with increase in density of C. bipunctata, whereas leaf and stem dry matter of the MWES-tolerant maize variety “30D44” decreased little. These results indicate that earlier planting together with the use of MWES-tolerant varieties can significantly improve MWES control on forage maize.     

Detection of antibodies against Akabane virus in bovine sera by enzyme-linked immunosorbent assay

An enzyme-linked immunonosorbent assay was established for detection of antibodies to Akabane virus in bovine sera. The assay was shown to be a useful serological tool for studies on Akabane virus infection.