Jooske IJzer

Microplastic in a macro filter feeder: Humpback whale Megaptera novaeangliae

Marine filter feeders are exposed to microplastic because of their selection of small particles as food source. Baleen whales feed by filtering small particles from large water volumes. Macroplastic was found in baleen whales before. This study is the first to show the presence of microplastic in intestines of a baleen whale (Megaptera novaeangliae). Contents of its gastrointestinal tract were sieved, dissolved in 10% potassium hydroxide and washed. From the remaining dried material, potential synthetic polymer particles were selected based on density and appearance, and analysed by Fourier transform infrared (FTIR) spectroscopy. Several polymer types (polyethylene, polypropylene, polyvinylchloride, polyethylene terephthalate, nylon) were found, in varying particle shapes: sheets, fragments and threads with a size of 1mm to 17cm. This diversity in polymer types and particle shapes, can be interpreted as a representation of the varying characteristics of marine plastic and the unselective way of ingestion by M. novaeangliae.

Endocrinology: Hyperaldosteronism in a cat with metastasised adrenocortical tumour

Summary In a 12‐year‐old male shorthaired cat with attacks of hypo‐kalaemic muscular weakness in spite of oral potassium supplementation, highly elevated plasma aldosterone concentrations in combination with low plasma renin activity pointed to primary hyperaldosteronism. Ultrasonography and computed tomography revealed a large left‐sided adrenal tumour growing into the phrenicoabdominal vein and the caudal vena cava. The tumour and its intravascular extension were surgically removed, but the subsequent stenosis of the caudal vena cava caused congestion and renal failure. At autopsy pulmonary micrometastases of the aldosteronoma were found.

Aldosteronoma in a dog with polyuria as the leading symptom

In a 10-year-old castrated male shorthaired German pointer polyuria was associated with slight hypokalemia, hypophosphatemia and alkalosis, as well as elevated plasma concentrations of a glucocorticoid-inducible iso-enzyme of alkaline phosphatase. Repeated measurements of urinary corticoids and normal suppressibility of the hypothalamus-pituitary-adrenocorticial axis excluded glucocorticoid excess. Urine osmolality (Uosm) did not increase during administration of the vasopressin analogue desmopressin. At the time water deprivation had caused Uosm to rise from 300 to 788 mOsm/kg, there was also plasma hypertonicity. During hypertonic saline infusion the osmotic threshold for vasopressin release was increased. The combination of elevated plasma aldosterone concentrations and unmeasurably low plasma renin activity pointed to primary hyperaldosteronism. As initially computed tomography (CT) did not reveal an adrenocortical lesion, the dog was treated with the aldosterone antagonist spironolactone. This caused Uosm to rise in a dose-dependent manner. However, well-concentrated urine was only achieved with doses that gave rise to adverse effects. Once repeated CT, using 2-mm-thick slices, had revealed a small nodule in the cranial pole of the left adrenal, unilateral adrenalectomy was performed which resolved the polyuria completely. Also the plasma concentrations of kalium, aldosterone and renin activity returned to within their respective reference ranges. The adrenocortical nodule had the histological characteristics of an aldosteronoma, with the non-affected zona glomerulosa being atrophic.In this dog with primary hyperaldosteronism the polyuria was characterized by vasopressin resistance and increased osmotic threshold of vasopressin release, similar to the polyuria of glucocorticoid excess. The possibility is discussed that the polyuria of glucocorticoid excess is actually a mineralocorticoid effect.

Morphological characterisation of portal myofibroblasts and hepatic stellate cells in the normal dog liver

BackgroundHepatic fibrosis is a common outcome of hepatic injury in both man and dog. Activated fibroblasts which develop myofibroblastic characteristics play an essential role in hepatic fibrogenesis, and are comprised of three subpopulations: 1) portal or septal myofibroblasts, 2) interface myofibroblasts and 3) the perisinusoidally located hepatic stellate cells (HSC). The present study was performed to investigate the immunohistochemical characteristics of canine portal myofibroblasts (MF) and HSC in the normal unaffected liver as a basis for further studies on fibrogenesis in canine liver disease.ResultsIn the formalin-fixed and paraffin embedded normal canine liver vimentin showed staining of hepatic fibroblasts, probably including MF in portal areas and around hepatic veins; however, HSC were in general negative. Desmin proved to react with both portal MF and HSC. A unique feature of these HSC was the positive immunostaining for alpha-smooth muscle actin (α-SMA) and muscle-specific actin clone HHF35 (HHF35), also portal MF stained positive with these antibodies. Synaptophysin and glial fibrillary acidic protein (GFAP) were consistently negative in the normal canine liver. In a frozen chronic hepatitis case (with expected activated hepatic MF and HSC), HSC were negative to synaptophysin, GFAP and NCAM. Transmission electron microscopy (TEM) immunogold labelling for α-SMA and HHF35 recognized the positive cells as HSC situated in the space of Disse.ConclusionIn the normal formalin-fixed and paraffin embedded canine liver hepatic portal MF and HSC can be identified by α-SMA, HHF35 and to a lesser extent desmin immunostaining. These antibodies can thus be used in further studies on hepatic fibrosis. Synaptophysin, GFAP and NCAM do not seem suitable for marking of canine HSC. The positivity of HSC for α-SMA and HHF35 in the normal canine liver may eventually reflect a more active regulation of hepatic sinusoidal flow by these HSC compared to other species.

Regenerative and fibrotic pathways in canine hepatic portosystemic shunt and portal vein hypoplasia, new models for clinical hepatocyte growth factor treatment.

BackgroundWe analyzed two spontaneous dog diseases characterized by subnormal portal perfusion and reduced liver growth: (i) congenital portosystemic shunts (CPSS) without fibrosis and (ii) primary portal vein hypoplasia (PPVH), a disease associated with fibrosis. These pathologies, that lack inflammation or cholestasis, may represent simplified models to study liver growth and fibrosis. To investigate the possible use of those models for hepatocyte growth factor (HGF) treatment, we studied the functionality of HGF signaling in CPSS and PPVH dogs and compared this to aged-matched healthy controls.ResultsWe used quantitative real-time polymerase chain reaction (Q-PCR) to analyze the mRNA expression of HGF, transforming growth factor β1 (TGF-β1), and relevant mediators in liver biopsies from cases with CPSS or PPVH, in comparison with healthy control dogs. CPSS and PPVH were associated with a decrease in mRNA expression of HGF and of MET proto-oncogene (c-MET). Western blot analysis confirmed the Q-PCR results and showed that intracellular signaling components (protein kinase B/Akt, ERK1/2, and STAT3) were functional. The TGF-β1 mRNA levels were unchanged in CPSS whereas there was a 2-fold increase in PPVH indicating an active TGF-β1 pathway, consistent with the observation of fibrosis seen in PPVH. Western blots on TGF-β1 and phosphorylated Smad2 confirmed an activated pro-fibrotic pathway in PPVH. Furthermore, Q-PCR showed an increase in the amount of collagen I present in PPVH compared to CPSS and control, which was confirmed by Western blot analysis.ConclusionThe pathophysiological differences between CPSS and PPVH can adequately be explained by the Q-PCR measurements and Western blots. Although c-MET levels were reduced, downstream signaling seemed to be functional and provides a rational for HGF-supplementation in controlled studies with CPSS and PPVH. Furthermore both diseases may serve as simplified models for comparison with more complex chronic inflammatory diseases and cirrhosis.

Transforming growth factor beta-1 signalling in canine hepatic diseases: new models for human fibrotic liver pathologies.

Abstract: Background/aims: The purpose of this study was to validate spontaneous chronic hepatitis and cirrhosis in dogs as a potential large animal model for fibrotic liver disease in humans by evaluating their molecular pathophysiology.

Expression of Hepatocyte Growth Factor and the Proto-oncogenic Receptor c-Met in Canine Osteosarcoma

Hepatocyte growth factor (HGF) and the proto-oncogenic receptor c-Met are implicated in growth, invasion, and metastasis in human cancer. Little information is available on the expression and role of both gene products in canine osteosarcoma. We hypothesized that the expression of c-Met is associated with malignant histologic characteristics, a short survival time, and a reduced disease-free interval in canine osteosarcoma. Quantitative real-time polymerase chain reaction was used to analyze the messenger RNA (mRNA) expression of both HGF and c-Met in 59 canine osteosarcoma samples. The relationship between HGF and c-Met expression, patient outcome, and histologic characteristics of the tumor were studied. Western blot analysis was performed to investigate the presence of active HGF protein. The expression pattern of c-Met in 16 slides of canine osteosarcoma was identified by immunohistochemistry. Coexpression of HGF and c-Met mRNA in all canine osteosarcoma samples suggested autocrine or paracrine receptor activation. A significant, moderately positive correlation was found between c-Met and HGF mRNA expression. c-Met mRNA expression was not associated with survival time or disease-free interval. Expression of c-Met was significantly associated with metastasis via the lymphogenic route. Immunolabeling with c-Met revealed a cytoplasmic staining pattern in all osteosarcoma cell types. In this study, c-Met mRNA expression in canine osteosarcoma was found to be of no influence on survival time and disease-free interval. Further studies are necessary to confirm the involvement of the c-Met pathway in the lymphogenic route of metastasis.

Characterisation of the hepatic progenitor cell compartment in normal liver and in hepatitis: an immunohistochemical comparison between dog and man.

The liver progenitor cell compartment in the normal canine liver and in spontaneous canine acute (AH) and chronic hepatitis (CH) was morphologically characterised and compared to its human equivalents. Immunohistochemistry was performed for cytokeratin-7 (CK7), human hepatocyte marker (Hep Par 1), multidrug resistance-associated protein-2 (MRP2), and breast cancer resistance protein (BCRP) on paraffin and frozen sections from canine and human tissues. Normal liver showed similar morphology and immunohistochemical reaction of the progenitor cell compartment/canal of Hering in man and dog. In addition, a ductular reaction, comparable in terms of severity, location and immunohistochemical characteristics, was observed in canine and human AH and CH. CK7 was a good marker for canine progenitor cells, including intermediate cells, which were positively identified in cases of AH and CH. In both species, BCRP was expressed in both hepatocytes and bile ducts of the normal liver, and in ductular reaction in AH and CH. MRP2 detected bile canalicular membranes in man and dog. These findings underline the similarities between canine and human liver reaction patterns and may offer mutual advantage for comparative research in human and canine spontaneous liver diseases.

Persistent Mullerian duct syndrome in a Miniature Schnauzer dog with signs of feminization and a Sertoli cell tumour

A 5-year-old male Miniature Schnauzer was presented with unilateral cryptorchidism and signs of feminization. Abdominal ultrasonography revealed an enlarged right testis and a large, fluid-filled cavity that appeared to arise from the prostate. Computed tomography revealed the cavity to be consistent with an enlarged uterine body, arising from the prostate, and showed two structures resembling uterine horns that terminated close to the adjacent testes. The dog had a normal male karyotype, 78 XY. Gonadohysterectomy was performed and both the surgical and the histological findings confirmed the presence of a uterus in this male animal, resulting in a diagnosis of persistent Mullerian duct syndrome (PMDS). The enlarged intra-abdominal testis contained a Sertoli cell tumour. Computed tomography proved to be an excellent diagnostic tool for PMDS.

The progenitor cell compartment in the feline liver: an (immuno)histochemical investigation.

The hepatic progenitor compartment is of vital importance in liver regeneration when hepatocellular replication is impaired, as it occurs in acute fulminant hepatitis or severe liver fibrosis. It consists of resident progenitor cells in the normal liver, and ductular reaction and intermediate hepatobiliary cells in diseased livers. An histologic and immunohistochemical study was conducted to demonstrate putative hepatic progenitor cells in the normal liver (n = 5) and in a range of hepatic diseases (n = 13) in the cat. Formalin-fixed, paraffin-embedded specimens were stained with HE, the van Gieson stain, and the reticulin stain according to Gordon and Sweet, and immunohistochemically stained for cytokeratin-7 (CK7), human hepatocyte marker 1 (Heparl), and multidrug resistance-binding protein-2/ATP binding cassette C2 (MRP2). The normal feline liver contains a liver progenitor cell morphologically similar to humans and dogs, which resides in the canal of Hering. In acute and chronic feline liver diseases a ductular reaction is present, whether in the parenchyma or in a portal or septal location. The putative progenitor cells could easily be demonstrated by staining for CK7, whereas they were generally negative for Heparl and MRP2. In a parenchymal ductular reaction mitotic figures and cells with an intermediate hepatobiliary phenotype could be demonstrated. This is the first account of hepatic progenitor cells in feline liver.