Tissue distribution of infectious pancreatic necrosis virus serotype Sp in naturally infected cultured rainbow trout,Oncorhynchus mykiss (Walbaum): an immunohistochemical and nested‐PCR study

This study investigates the occurrence and distribution pattern of infectious pancreatic necrosis virus (IPNV) within the pancreas, liver, kidney and spleen of naturally infected cultured rainbow trout, Oncorhynchus mykiss (Walbaum), using immunohistochemistry (IHC). A nested PCR was also employed to confirm the presence of the virus in the pooled tissues of the specimens. All the examined tissues except spleen were immunohistochemically positive for IPNV, but staining intensity and distribution pattern varied. The kidney tubules had the most intense and widespread staining by IHC, indicating a specific tissue tropism at least for this particular serotype. The nucleotide sequence had the greatest identity with the Sp serotype confirming the presence of the nucleic acid of IPNV in the pooled tissues. Based on the present findings, it could be concluded that the absence of lesions consistent with infectious pancreatic necrosis (IPN) disease in the H&E‐stained sections cannot rule out the presence of the IPNV, and the use of an alternative rapid confirmatory method such as IHC with formalin‐fixed, paraffin‐embedded tissue sections is helpful for the final diagnosis of IPN in rainbow trout.     

Infectious pancreatic necrosis virus establishes an asymptomatic carrier state in kidney leucocytes of juvenile Atlantic cod, Gadus morhua L

Juvenile Atlantic cod (10 g) were infected with infectious pancreatic necrosis virus (IPNV) by intraperitoneal injection and cohabitation. Fish showed no signs of disease but IPNV could be re-isolated from kidney tissue for up to 12 weeks. On weeks 2, 5, 8, 10, 11 and 12 following infection, kidney leucocytes were fractionated on Percoll gradients, and cells separated into plastic adherent and non-adherent cell populations after overnight incubation. IPNV was detectable in lysates of both cell populations and in supernatants by culture in CHSE-214 cells. Wells containing 10(5)-10(6) macrophages had an IPNV TCID(50) of about 10(3)/well and in serially diluted macrophages the minimum number of cells required to detect virus ranged from 10(1) to 10(4). These data indicate that about one in 10(4) macrophages were infected and the mean number of virus/infected cell was about 10. Replication of IPNV in the macrophages was low as the titre of the virus in macrophage lysates did not increase between days 1 and 3 of culturing the macrophages, but virus was released into the supernatant over this time.     

Analysis of the incidence of infectious pancreatic necrosis mortality in pedigreed Atlantic salmon, Salmo salar L., populations

A total of 77,124 Atlantic salmon post-smolts, representing 197 full-sib families produced by 149 males and 197 females, experienced a field challenge from infectious pancreatic necrosis virus (IPNV), following transfer to three separate seawater sites. The first IPN mortality was observed 45 days after transfer, and the duration of the epidemic varied between 37 and 92 days among sites. Mortalities were traced to their parental families by PIT (Passive Integrated Transpondes) tag records and DNA genotyping. Full-sib family mean incidence of mortality was calculated for each family on each site. Heritabilities were estimated based on the heterogeneity of chi-square using incidence within half-sib families and the variance in incidence among full-sib families, both on the observed and underlying liability scale. The observed correlation among families across sites was used to estimate genetic correlations. The overall mortality rate was 10.8%, with only small differences between sites, ranging from 10.3% to 11.9%. Heritabilities on the liability scale were found to be moderate to strong, and ranged between 0.24 and 0.81, with a pooled estimate of 0.43, greater than is typically associated with disease traits. Genetic correlations among sites were all substantial, between 0.71 and 0.78, and indicated that a substantial component of the genetic variation displayed within sites was common to all. The results show that field challenges can yield very good genetic information on family differences in resistance, especially when replicated over sites, which may then be developed for use in selection for breeding strains of Atlantic salmon with greater resistance to IPN.     

胰岛β细胞系研究概况

胰岛具有控制能量代谢的重要作用。全球糖尿病发病率快速增加,引起了科学家对胰岛细胞生物学研究的重视。然而,胰岛分离困难,且费用昂贵,胰岛功能在生物及分子水平上很难获得更加全面的认识。过去胰岛来源的细胞系由于其分化不稳定,仅作为原代胰岛细胞的替代品。如今,人们通过紫外线照射、病毒转染等方法建立了多种胰岛β细胞系,保持了很多正常胰岛的关键功能特性,而成为研究胰岛细胞生物学的有效工具。不同种类细胞系的生物学特征各有不同,根据研究需要,采用基因工程的方法创建更适合的亚系,是迄今为止改善细胞系特性的主要方法,为不同方面的研究提供便利。     

Ultrasonographic features of insulinoma in six ferrets

Insulinoma is a functional, insulin‐secreting tumor, arising from the beta islet cells of the pancreas. It is one of the most common neoplasms in ferrets and has been associated with clinical signs of hypoglycemia, such as ptyalism, pawing at the mouth, seizures, lethargy, and coma. The ultrasonographic features of insulinoma in ferrets have not been previously reported. The purpose of this retrospective case series study was to describe the ultrasonographic features of confirmed insulinoma in a group of ferrets. Inclusion criteria were abdominal ultrasound examination and histological confirmed insulinoma by surgical biopsy. Six ferrets met the inclusion criteria, all of which had multiple hypoglycemic episodes. Ultrasonographic images were reviewed and the characteristics of the pancreatic nodules were recorded. Twenty‐eight pancreatic nodules were observed in the six ferrets and were primarily hypoechoic (89.3%, 25/28) and homogenous (46.4%, 13/28) with a smooth margin (78.6%, 22/28). The distribution of the pancreatic nodules was 46.4% in the left lobe, 50% in the right lobe, and 3.6% in the body of the pancreas. The sizes of the pancreatic nodules varied from 1.5 × 1.5 to 4.1 × 5.6 mm. All of the pancreatic nodules removed from surgery were histopathologically confirmed as insulinoma. The findings indicated that insulinoma in ferrets could be detected through ultrasonography, which may facilitate diagnosis and preoperative surgical planning.     

Analytical validation of an ELISA for measurement of canine pancreas‐specific lipase

Background: The diagnosis of canine pancreatitis is challenging. Clinical presentation often includes nonspecific clinical signs, such as vomiting, anorexia, and abdominal discomfort. Increased serum lipase activity can be indicative of pancreatitis; however, it can also be increased with other conditions. An immunoassay for measurement of canine pancreas‐specific lipase in canine serum that would be suitable for commercial application and provide rapid results would be beneficial. Objective: The goal of this study was to validate the Spec cPL assay, a commercially available ELISA for the quantitative measurement of canine pancreas‐specific lipase. Methods: Dynamic range, dilutional linearity, precision, interfering substances, assay stability, and reproducibility were investigated for analytical validation. The method was compared with the reference assay, canine pancreatic lipase immunoreactivity (cPLI), and included evaluation of a sample population of dogs and bias. Results: Analytical validation showed a dynamic range of 36–954 μg/L; good precision (intra‐ and interassay coefficient of variation <12%); absence of interference from lipid, hemoglobin, or bilirubin; 12‐month kit stability; and good reproducibility. Method comparison showed a positive bias relative to the cPLI reference method; however, the bias can be accommodated by adjustment of decision limits. The upper limit of the reference interval for Spec cPL was determined to be 216 μg/L based on the upper 97.5th percentile of results from 93 clinically healthy, kennel‐housed dogs. Conclusions: Validation data demonstrated that the Spec cPL assay provides reproducible results for canine pancreas‐specific lipase. A readily available assay for measurement of this enzyme allows broader clinical utilization of this analytical tool, generating timely results to aid in the diagnosis of canine pancreatitis.     

Metastatic pancreatic polypeptide‐secreting islet cell tumor in a dog

Abstract: A 14‐year‐old female spayed Golden Retriever was presented to the University of Florida's Veterinary Medical Center with history of lymphoplasmacytic gastroenteritis, intermittent vomiting, watery diarrhea, and weight loss for over a year. CBC, biochemical profile, and urinalysis were within reference intervals. Abdominal ultrasonographic examination revealed mesenteric and jejunal lymphadenopathy and hyperechoic hepatic nodules. Cytologic examination of the enlarged lymph nodes revealed loosely cohesive cells with moderate nuclear pleomorphism and rare punctate eosinophilic cytoplasmic granules. The cytologic interpretation was metastatic neuroendocrine neoplasia. On surgical exploration, a mass was detected in the right lobe of the pancreas. Histologic evaluation determined the mass to be an islet cell tumor. Approximately 98% of cells were positive by immunolabeling for pancreatic polypeptide (PP), and only rare cells were positive for insulin or somatostatin. All cells were negative for glucagon, gastrin, vasoactive intestinal polypeptide, protein gene product 9.5, synaptophysin, and chromogranins A and B. Pancreatic tumors that primarily produce PP are rare in dogs, and this is the first report of both the cytologic and histologic features of an islet cell tumor predominantly secreting PP. Clinical signs for these tumors are typically absent or nonspecific; signs may include watery diarrhea, as noted in this dog, although the diarrhea may have resulted from lymphoplasmacytic gastroenteritis. Additional case studies are needed to further characterize the cytomorphologic features and clinical presentation of PP‐secreting islet cell tumor, or polypeptidoma, in dogs.     

Avarol Induces Apoptosis in Pancreatic Ductal Adenocarcinoma Cells by Activating PERK–eIF2α–CHOP Signaling

Avarol is a sesquiterpenoid hydroquinone with potent cytotoxicity. Although resolving endoplasmic reticulum (ER) stress is essential for intracellular homeostasis, erratic or excessive ER stress can lead to apoptosis. Here, we reported that avarol selectively induces cell death in pancreatic ductal adenocarcinomas (PDAC), which are difficult to treat owing to the availability of few chemotherapeutic agents. Analyses of the molecular mechanisms of avarol-induced apoptosis indicated upregulation of ER stress marker BiP and ER stress-dependent apoptosis inducer CHOP in PDAC cells but not in normal cells, suggesting that avarol selectively induces ER stress responses. We also showed that avarol activated the PERK–eIF2α pathway but did not affect the IRE1 and ATF6 pathways. Moreover, CHOP downregulation was significantly suppressed by avarol-induced apoptosis. Thus, the PERK–eIF2α–CHOP signaling pathway may be a novel molecular mechanism of avarol-induced apoptosis. The present data indicate that avarol has potential as a chemotherapeutic agent for PDAC and induces apoptosis by activating the PERK–eIF2α pathway.     

Continuous exposure to infectious pancreatic necrosis virus during early life stages of rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout, Oncorhynchus mykiss (Walbaum), were exposed continuously to infectious pancreatic necrosis virus (IPNV) at 0, 10¹, 10³ or 10⁵ plaque forming units (pfu) L⁻¹ of water to estimate the effects of chronic IPNV exposure on early life stages. Fish density averaged 35 fish L⁻¹ (low density) or 140 fish L⁻¹ (high density), and the tank flow rate was 250 mL⁻¹ min. Virus exposure began at 6 days before hatch and continued until fish were 44 days old. Cumulative per cent mortality, analysis of survival and hazard functions, and discrete-time event analysis were used to explore the patterns of survival and mortality. In eggs and fish exposed to IPNV, mortality significantly greater than in the 0 pfu L⁻¹ exposure did not occur until IPNV concentration was 10⁵ pfu L⁻¹ at low fish density and 10³ pfu IPNV L⁻¹ at high fish density. These results suggest that in the natural aquatic environment, where rainbow trout densities are likely to be considerably lower than in this study, mortality resulting from infection with IPNV will very likely not occur when ambient concentrations of virus are ≤10³ pfu IPNV L⁻¹. In aquaculture rearing units, trout density is likely to be as high or higher than the densities used in this study. Therefore, continuous inputs of virus at concentrations greater than 10¹ pfu L⁻¹ may result in IPN epidemics in aquaculture facilities.