Joy Archer

Observational study of 14 cases of chronic pancreatitis in dogs

This study reports the clinical, clinicopathological and ultrasonographic findings from dogs with chronic pancreatitis (CP). Fourteen dogs with clinical signs consistent with CP and histological confirmation of the disease were evaluated. Abdominal ultrasound and clinical pathology results were recorded. Sensitivities of pancreatic enzymes for diagnosis of CP were calculated with two different cut-off values. The mean age of affected dogs was 9.1 years. Spaniels were the most common breed with CP, representing seven of the 14 dogs in this study. CP was histologically severe in nine cases. Most dogs showed chronic low-grade gastrointestinal signs and abdominal pain. Five dogs had exocrine pancreatic insufficiency and five dogs had diabetes mellitus. The sensitivity of elevated trypsin-like immunoreactivity for CP was 17 per cent. The sensitivities of canine pancreatic lipase immunoreactivity, lipase and amylase for CP were 44 to 67 per cent or 14 to 28 per cent depending on the cut-off value used. Cholesterol was elevated in 58 per cent of samples. Liver enzymes were often elevated. The pancreas appeared abnormal on 56 per cent of ultrasound examinations. Ten dogs had died by the end of the study period; only one case was due to CP.

Over-expression of Plk4 induces centrosome amplification, loss of primary cilia and associated tissue hyperplasia in the mouse

To address the long-known relationship between supernumerary centrosomes and cancer, we have generated a transgenic mouse that permits inducible expression of the master regulator of centriole duplication, Polo-like-kinase-4 (Plk4). Over-expression of Plk4 from this transgene advances the onset of tumour formation that occurs in the absence of the tumour suppressor p53. Plk4 over-expression also leads to hyperproliferation of cells in the pancreas and skin that is enhanced in a p53 null background. Pancreatic islets become enlarged following Plk4 over-expression as a result of equal expansion of α- and β-cells, which exhibit centrosome amplification. Mice overexpressing Plk4 develop grey hair due to a loss of differentiated melanocytes and bald patches of skin associated with a thickening of the epidermis. This reflects an increase in proliferating cells expressing keratin 5 in the basal epidermal layer and the expansion of these cells into suprabasal layers. Such cells also express keratin 6, a marker for hyperplasia. This is paralleled by a decreased expression of later differentiation markers, involucrin, filaggrin and loricrin. Proliferating cells showed an increase in centrosome number and a loss of primary cilia, events that were mirrored in primary cultures of keratinocytes established from these animals. We discuss how repeated duplication of centrioles appears to prevent the formation of basal bodies leading to loss of primary cilia, disruption of signalling and thereby aberrant differentiation of cells within the epidermis. The absence of p53 permits cells with increased centrosomes to continue dividing, thus setting up a neoplastic state of error prone mitoses, a prerequisite for cancer development.

B cell lymphoma and myeloma in murine Gaucher's disease

Multiple myeloma and B cell lymphoma are leading causes of death in Gauchers disease but the nature of the stimulus driving the often noted clonal expansion of immunoglobulin‐secreting B cells and cognate lymphoid malignancy is unknown. We investigated the long‐term development of B cell malignancies in an authentic model of non‐neuronopathic Gauchers disease in mice: selective deficiency of β‐glucocerebrosidase in haematopoietic cells [Gbatm1Karl/tm1KarlTg(Mx1‐cre)1Cgn/0, with excision of exons 9–11 of the murine GBA1 gene, is induced by poly[I:C]. Mice with Gauchers disease showed visceral storage of β‐glucosylceramide and greatly elevated plasma β‐glucosylsphingosine [median 57.9 (range 19.8–159) nm; n = 39] compared with control mice from the same strain [median 0.56 (range 0.04–1.38) nm; n = 29] (p < 0.0001). Sporadic fatal B cell lymphomas developed in 11 of 21 GD mice (6–24 months) but only two of eight control animals developed tumours by age 24 months. Unexpectedly, most mice with overt lymphoma had absent or few Gaucher cells but local inflammatory macrophages were present. Eleven of 39 of Gaucher mice developed monoclonal gammopathy, but in the control group only one animal of 25 had clonal immunoglobulin abnormalities. Seven of 10 of the B cell lymphomas were found to secrete a monoclonal paraprotein and the lymphomas stained intensely for pan‐B cell markers; reactive T lymphocytes were also present in tumour tissue. In the Gaucher mouse strain, it was notable that, as in patients with this disease, CD138+ plasma cells frequently surrounded splenic macrophages engorged with glycosphingolipid. Our strain of mice, with inducible deficiency of β‐glucocerebrosidase in haematopoietic cells and a high frequency of sporadic lethal B cell malignancies, faithfully recapitulates human Gauchers disease: it serves as a tractable model to investigate the putative role of bioactive sphingolipids in the control of B cell proliferation and the pathogenesis of myelomatosis—the most prevalent human cancer associated with this disorder. Copyright

The Cardiac Biomarker NT-proBNP Is Increased in Dogs with Azotemia

BACKGROUND Amino-terminal probrain natriuretic peptide (NT-proBNP) has been proposed as a useful biomarker for heart disease in dogs. In humans, decreased glomerular filtration rate (GFR) increases NT-proBNP. OBJECTIVE To investigate whether decreased GFR as indicated by plasma creatinine concentration is associated with increased NT-proBNP in dogs without heart disease. ANIMALS Four groups of dogs: healthy (n= 39), azotemic (n= 36), heart disease (n= 37), and congestive heart failure (CHF) (n= 7) presented to 2 teaching hospitals. METHODS Prospective observational cohort study. Plasma creatinine concentration and NT-proBNP were measured in every dog. Nonparametric tests were used to compare the differences among groups. The median and actual results for each group were compared with the manufacturers recommended and previously published suggestions for cut-off values for diagnosis of heart disease. RESULTS Median (range) plasma creatinine concentration was 1.47 (1.06-1.70), 4.36 (1.74-15.6), 1.22 (0.69-1.91), and 1.45 (0.63-1.64) mg/dL and median (range) NT-proBNP was 118 (2-673), 556 (37-1,819), 929 (212-5,658), and 3,144 (432-5,500) pmol/L for the healthy, azotemic, heart disease, and CHF groups, respectively. Pair-wise comparison indicated a significant difference among all groups for NT-proBNP (P< or = .049). Plasma creatinine concentration was significantly higher in the azotemic group compared with other groups (P < .001) but there was no significant among other groups. Application of 3 recommended cut-off values led to misclassification of dogs with azotemia as having heart disease. CONCLUSIONS Azotemia results in NT-proBNP being increased to concentrations reported as diagnostic of heart disease or heart failure in dogs. Care should be employed when interpreting the results of NT-proBNP in patients with known or possible increased plasma creatinine concentration.

Inhibition of UDP-glucosylceramide synthase in mice prevents Gaucher disease-associated B-cell malignancy

Clonal B‐cell proliferation is a frequent manifestation of Gaucher disease – a sphingolipidosis associated with a high risk of multiple myeloma and non‐Hodgkin lymphoma. Gaucher disease is caused by genetic deficiency of acid β‐glucosidase, the natural substrates of which (β‐d‐glucosylceramide and β‐d‐glucosylsphingosine) accumulate, principally in macrophages. Mice with inducible deficiency of β‐glucosidase [Gba(tm1Karl/tm1Karl)Tg(MX1‐cre)1Cgn/0] serve as an authentic model of human Gaucher disease; we have recently reported clonal B‐cell proliferation accompanied by monoclonal serum paraproteins and cognate tumours in these animals. To explore the relationship between B‐cell malignancy and the biochemical defect, we treated Gaucher mice with eliglustat tartrate (GENZ 112638), a potent and selective inhibitor of the first committed step in glycosphingolipid biosynthesis. Twenty‐two Gaucher mice received 300 mg/kg of GENZ 112638 daily for 3–10 months from 6 weeks of age. Plasma concentrations of β‐d‐glucosylceramide and the unacylated glycosphingolipid, β‐d‐glucosylsphingosine, declined. After administration of GENZ 112638 to Gaucher mice for 3–10 months, serum paraproteins were not detected and there was a striking reduction in the malignant lymphoproliferation: neither lymphomas nor plasmacytomas were found in animals that had received the investigational agent. In contrast, 14 out of 60 Gaucher mice without GENZ 112638 treatment developed these tumours; monoclonal paraproteins were detected in plasma from 18 of the 44 age‐matched mice with Gaucher disease that had not received GENZ 112638. Long‐term inhibition of glycosphingolipid biosynthesis suppresses the development of spontaneous B‐cell lymphoma and myeloma in Gaucher mice. Copyright

High serum troponin I concentration as a marker of severe myocardial damage in a case of suspected exertional heatstroke in a dog

A young, overweight dog presented with sudden onset lethargy and collapse following exercise in warm environmental conditions. Investigations revealed systolic hypotension, multiform ventricular premature complexes, irregular myocardial echogenicity with poor left ventricular systolic function and a markedly elevated troponin cTnI (180ng/mL, reference range <0.3ng/mL) consistent with severe myocyte damage. Infectious causes of myocarditis were ruled out on the basis of serological and polymerase chain reaction blood tests. Exercise-induced malignant hyperthermia was excluded from the history, an exercise tolerance test and genetic testing for the RYR1 V547A mutation. The diagnosis was myocardial damage secondary to suspected exertional heatstroke, from which the dog recovered uneventfully over a number of weeks and serum troponin normalised. This is the first case report in any species including man, documenting high troponin as a marker of severe myocardial damage following suspected heatstroke.

Initial evaluation of canine urinary cystatin C as a marker of renal tubular function

OBJECTIVES To evaluate the performance of a particle-enhanced turbidimetric assay for measuring canine urinary cystatin C and to investigate if the urinary cystatin C to creatinine ratio is higher in dogs with renal disease than in non-renal disease dogs. METHODS Urinary cystatin C was measured by particle-enhanced turbidimetric assay using an avian antihuman cystatin C antibody and the performance of this assay was evaluated. Clinical relevance was tested in 46 dogs that were divided into three groups: healthy dogs (n=14), non-renal disease dogs (n=17) and dogs with renal disease (n=15). RESULTS The assay was linear (R(2)=0·99) and precise (mean intra- and inter-assay coefficients of variation were 2·3 and 2·9%, respectively). The recovery was 111·5% and the limit of blank was 0·02 mg/L. Urinary cystatin C and urinary cystatin C to creatinine ratio differed significantly (P<0·001) between the three cohorts of dogs. CLINICAL SIGNIFICANCE Measurement of cystatin C by particle-enhanced turbidimetric assay performed with high precision and linearity. This assay can be processed on automated clinical chemistry analysers making it widely available to commercial laboratories. Urinary cystatin C to creatinine ratio can differentiate dogs with renal disease from dogs without renal disease. These preliminary results suggest that urinary cystatin C to creatinine ratio is a promising marker for evaluating renal tubular function.

Cardiac biomarkers: a review

Cardiac injury can develop secondary to compromise due to disease or drug toxicity, among other causes. The clinical signs of cardiac problems can be confused with those of other conditions, such as respiratory disease. Therefore, specific, sensitive, rapid and inexpensive blood tests for cardiac injury are desirable. Cardiac troponins are uniquely expressed in the myocardium and increase with injury. Changes in serum concentrations of these have been found to be specific and sensitive indicators of such injury. Troponins are phylogenetically highly conserved proteins with > 95% homology between mammals. Thus assays developed for human serum can be used in other species. Natriuretic peptides have been more recently used as indicators of cardiac injury in humans. They are becoming more available for animals but homology is lower, therefore many animal species-specific assays need to be developed. These peptides are sensitive to changes in vasoconstriction and dilation within the heart and are used for the diagnosis and prognosis of heart failure in humans. Assays for endothelins and cardiotrophins have similar potential and are under development and evaluation for human use. Combinations of these tests can be followed by more specialised tests (e.g. echocardiography) to confirm the severity and type of injury that has occurred.

Histopathologic, immunohistochemical, and cytologic analysis of feline myeloma-related disorders: further evidence for primary extramedullary development in the cat.

Feline myeloma-related disorders (MRD) are rare neoplasms of plasma cells. The multistep transformation model of myeloma in humans is based on the premise that plasma cells undergo neoplastic transformation primarily within the intramedullary compartment and that over time they become poorly differentiated and metastasize to extramedullary locations. Historically, diagnostic criteria used for human multiple myeloma have been applied to the cat, with the assumption that feline MRD commonly arises in the intramedullary compartment. Our objectives were to describe the features of feline MRD confirmed by cytology, histopathology, histochemistry, and immunohistochemistry and to categorize these tumors. A priori hypotheses were 1) tumor category predicts survival and 2) cats with well-differentiated tumors commonly have extramedullary involvement in contrast to human myeloma patients. This multicenter, retrospective study identified 26 MRD cases. There was good agreement between histopathologic and cytologic tumor categorization. Histochemistry and immunohistochemistry were shown to be valuable adjunct tests in the diagnosis of MRD. Cats with well-differentiated tumors had increased median survival relative to those with poorly differentiated tumors (254 versus 14 days). We have reported that marked extramedullary involvement at initial clinical presentation is significantly more common in the cat than in human MRD patients. In this study, we demonstrate that cats with well-differentiated tumors more commonly have extramedullary involvement than human myeloma patients with well-differentiated tumors (90% versus 20%, P < 0.0002). These results contrast strongly with the human myeloma model of primary intramedullary neoplastic transformation and suggest that primary extramedullary neoplastic transformation may be more common in feline MRD.

Myeloma-related disorders in cats commonly present as extramedullary neoplasms in contrast to myeloma in human patients: 24 cases with clinical follow-up

Background:Myeloma‐related disorders (MRD) are rare neoplasms of plasma cells. Published case reports describe a diversity of clinical presentations with confusing terminology and diagnostic criteria as a consequence of the assumption that MRD in cats are analogous to those in dogs or humans. Objective: The aim of the study was to describe clinical, clinicopathologic and imaging findings, response to treatment, survival and possible associations with other diseases or vaccination in a large case series. A priori hypotheses were that cats with MRD commonly present with extramedullary involvement and uncommonly have radiographic bone lesions, in contrast to human patients. Animals:Twenty‐four cats with MRD confirmed by cytology or histopathology and immunohistochemistry. Method: A multicenter retrospective study was performed. Results:Two types of clinical presentation were observed. The first group (n = 17) had neoplasia involving abdominal organs, bone marrow, or both. All developed systemic clinical signs and paraproteinemia. Five of 7 cats that received chemotherapy improved clinically or had decreased serum globulin concentration (median survival, 12.3 months; range, 8.5–22 months). The second group comprised 7 cats with skin masses, 2 of which were paraproteinemic and developed rapidly worsening systemic signs. In cats without systemic signs, excision of the skin masses appeared to be associated with prolonged survival (up to 2.4 years). Cats with MRD commonly presented with extramedullary involvement (67%), versus humans with MRD (5%) (P < .001), and uncommonly presented with radiographic bone lesions (8%) versus humans with MRD (80%) (P < .001). Conclusions: Radiographic bone lesions are uncommon in cats with MRD and extramedullary presentation is common, relative to human myeloma.