Measurement of feline-specific pancreatic lipase aids in the diagnosis of pancreatitis in cats.

OBJECTIVE: To establish a reference interval for a feline-specific pancreatic lipase assay (Spec fPL test; Idexx Laboratories Inc) in healthy cats and determine the sensitivity and specificity of the Spec fPL test in a large group of ill cats with and without pancreatitis. ANIMALS: 41 healthy cats, 141 cats with clinical signs consistent with pancreatitis, and 786 stored sera with known feline pancreatic lipase immunoreactivity (fPLI) concentrations. METHODS: This was a prospective, cross-sectional, nonrandomized study. Based on a detailed review of the medical history and results of physical examination, CBC, serum biochemical profile, urinalysis, abdominal ultrasonography, and clinical outcome, each cat was categorized by 2 board-certified internists masked to the fPLI test results into 1 of 6 categories from definitely pancreatitis to definitely not pancreatitis. RESULTS: The reference interval for the Spec fPL test, determined from the central 95th percentile of results from healthy cats, was fPLI of 0.7 to 3.5 µg/L. An fPLI concentration of ≥ 5.4 µg/L was determined to be consistent with pancreatitis. With an fPLI of 5.4 µg/L as the diagnostic cutoff, the sensitivity of the Spec fPL test for feline pancreatitis (definitely pancreatitis and probably pancreatitis) was 79.4%, the specificity for cats characterized as probably not pancreatitis and definitely not pancreatitis was 79.7%, and positive and negative predictive values were 69% and 87%, respectively. CLINICAL RELEVANCE: These findings support the use of the Spec fPL test as a valuable diagnostic test for feline pancreatitis.

Suspected phenobarbital-induced pseudolymphoma in a cat.

CASE DESCRIPTION: A 4.5-year-old spayed female domestic shorthair cat was evaluated because of a generalized seizure disorder that developed after an anesthesia-related hypoxic event. CLINICAL FINDINGS: Following administration of phenobarbital, the seizures stopped but the cat developed severe generalized lymphadenopathy. Results of a CBC and serum biochemical analysis were unremarkable. Cytologic examination of the lymph nodes revealed a reactive lymphocyte population. Differential diagnoses included neoplasia and infection, but results of related diagnostic tests were all negative. TREATMENT AND OUTCOME: Treatment was changed from phenobarbital to levetiracetam. Ten days following discontinuation of phenobarbital, the lymph node enlargement resolved, and the cat remained free of seizures with levetiracetam as treatment. CLINICAL RELEVANCE: Pseudolymphoma and anticonvulsant hypersensitivity syndrome are recognized potential sequelae to anticonvulsant administration in humans. However, a pseudolymphoma-like reaction to anticonvulsants in veterinary species has not previously been reported. This case highlighted a potentially serious yet reversible sequela to phenobarbital treatment that may have been mistaken for more severe illness such as neoplasia.

Deficient inflammatory response to UV radiation in neonatal mice.

Mechanisms of juvenile susceptibility to cancer are not well understood. The immune response in neonates favors nonresponsiveness or T(H)2-dominant responses, raising the question of a role for neonatal immunity in this susceptibility. We have investigated the postulate that the inflammatory response differs in neonatal and adult skin. We found no inflammatory infiltrate into neonatal mouse skin in response to UV irradiation as a function of time, dose, or wavelength, although UV-induced DNA damage was readily detected. In contrast, UV irradiation of adult mice initiated a dose- and time-dependent influx of inflammatory cells, chiefly CD11b(+)Ly6G(+) neutrophils, into the skin, detected by immunohistochemistry and quantitated by FACS analysis. This inflammatory response was initiated by UVB (290-320 nm) but not by UVA (320-400 nm). Further, in neonates, in contrast to adults, neither topical trinitrochlorobenzene (TNCB) nor i.p. thioglycollate initiated an inflammatory infiltrate. Conversely, topical TNCB applied to neonates was tolerogenic, resulting in a subsequent antigen-specific decrease of the contact-hypersensitivity response in adults. Neonatal blood contained abundant neutrophils, which exhibited impaired chemotaxis to the chemokine growth-related oncogene-alpha but efficient chemotaxis to the bacterial product fMLP, concomitant with decreased expression of CXCR2 but normal levels of CD11b. We propose this neonatal deficiency in the inflammatory response is a significant, previously unrecognized factor in neonatal immune tolerance and may contribute to neonatal susceptibility to cancer, including melanoma and other UV-induced cancers.

IgM paraprotein interference with hemoglobin measurement using the CELL-DYN 3500.

A 10-year-old male Labrador Retriever was presented for a 6-week history of polyuria, polydipsia, rear limb weakness, and ocular discharge. The dog had marked hyperproteinemia with an IgM monoclonal gammopathy, as determined by serum protein electrophoresis and immunoelectrophoresis. Cytologic findings in a lymph node aspirate were suggestive for lymphoma, which was confirmed and identified as B cell lineage by immunophenotyping and PCR antigen receptor rearrangement. In the CBC results, marked discrepancy was observed in the hemoglobin (HGB) concentration and MCHC obtained on a CELL-DYN 3500 analyzer (HGB 13.3 g/dL, MCHC 61.4 g/dL) as compared with an IDEXX LaserCyte analyzer (HGB 7.0 g/dL, MCHC 39.2 g/dL). To investigate this discrepancy, plasma was removed from an EDTA-anticoagulated blood sample from the patient, replaced with an equal volume of CELL-DYN diluent, and analyzed on the CELL-DYN. The resulting HGB (6.72 g/dL) and MCHC (33.5 g/dL) results were similar to those obtained initially on the LaserCyte. We concluded that precipitation of IgM paraprotein by the CELL-DYN lyzing reagent, which contains quaternary ammonium salts, falsely increased the spectrophotometric measurement of HGB on the CELL-DYN. The high MCHC was attributed to the false increase in HGB concentration. No interference with HGB measurement occurred with the LaserCyte, which uses a hypotonic solution to lyse RBCs before HGB determination. Paraprotein interference should be considered in veterinary patients with monoclonal gammopathy and unexpectedly high HGB and MCHC values.

Prospective diagnostic accuracy evaluation and clinical utilization of a modified assay for platelet-associated immunoglobulin in thrombocytopenic and nonthrombocytopenic dogs.

BACKGROUND: No diagnostic tests reliably distinguish primary immune-mediated thrombocytopenia (pIMT) from other causes of thrombocytopenia. OBJECTIVES: The purpose of the study was to evaluate diagnostic sensitivity and specificity using modified direct and indirect platelet-associated immunoglobulin (PAIg) assays and reticulated platelets (RP) by flow cytometry for the classification of thrombocytopenic dogs and differentiating pIMT. METHODS: Platelets were isolated from plasma samples of thrombocytopenic dogs and nonthrombocytopenic healthy and ill dogs. For direct PAIg, they were analyzed by flow cytometry after incubation with anti-human amylase fluorescein isothiocyanate (FITC, negative control), anti-canine IgG-FITC, anti-canine IgM-FITC, and anti-human CD61-conjugated fluorochrome (AF647). For indirect PAIg, platelets from normothrombocytic dogs were incubated with thrombocytopenic dog plasma and analyzed similar to direct PAIg. RP percentages were determined based on forward light scatter vs thiazole orange fluorescence. RESULTS: Seventy-five thrombocytopenic dogs, 16 nonthrombocytopenic ill dogs, and 24 healthy dogs were evaluated. Diagnostic sensitivity and specificity utilizing direct IgG was 29.4% and 75.9%, respectively; when combining direct/indirect assays (IgG/IgM), it was 76.5% and 65.5%, respectively, for distinguishing pIMT. For RP, no significant difference between pIMT and sIMT was noted. RP > 8% with positive PAIg had a sensitivity of 94% and specificity of 27.6% for distinguishing pIMT. There was a significant difference in platelet concentration and CD61% staining between control and pIMT. CONCLUSIONS: The combined modified assays resulted in fair diagnostic sensitivity and specificity for the diagnosis of pIMT. The modification of the immunoglobulin assays improved diagnostic accuracy; however, a single panel to accurately classify thrombocytopenia remains elusive.

Animal models of bone metastasis.

Animal models will continue to be indispensable to investigate the pathogenesis of bone metastasis in vivo, conduct preclinical chemotherapeutic, chemoprevention and genetic therapy studies, test gene delivery mechanisms, and identify metastasis suppressor and inducer genes. It is likely that the bone marrow microenvironment, such as the endothelial cells, stromal cells, hematopoietic cells, bone cells, and the intercellular matrix play important roles in the localization and clonal growth of cancer cells in bone. Given the complexity of bone metastasis, many genes are expected to be involved in the pathogenesis and few are likely indispensable. The use of genomic and proteomic approaches to study these animal models will identify key targets for therapeutic intervention. As we further refine these models and use imaging for real-time evaluation of cells, and eventually target genes, these models will more closely mirror human disease and will hopefully become more predictive of the human response to therapy.

New bone formation and osteolysis by a metastatic, highly invasive canine prostate carcinoma xenograft.

BACKGROUND: Osteoblastic metastases are commonly induced by prostate cancer. A canine prostate carcinoma xenograft (Ace-1) was developed and used to evaluate neoplastic prostate cell growth, metastasis, and effects on bone formation in nude mice. METHODS: Characteristics of the Ace-1 cells were evaluated with histopathology, radiography, and bioluminescent imaging (BLI). Immunohistochemistry and quantitative RT-PCR were used to evaluate the expression of factors important in the development of osteoblastic metastases. RESULTS: The Ace-1 cells were invasive and induced bone formation and destruction. Radiographs demonstrated a mixed osteoblastic/osteolytic reaction. Lung and lymph node metastases occurred in 30% of mice. The tumor cells expressed parathyroid hormone-related protein (PTHrP-141 isoform), cathepsin K, keratins 8/18, and vimentin, but not keratins 5/14, and were androgen receptor negative. Intracardiac (IC) injections resulted in metastases in vertebrae and long bones. CONCLUSIONS: The Ace-1 xenograft is a useful model for investigating the pathogenesis of prostate cancer invasion and mixed osteoblastic/osteolytic bone metastases.

Effects of transforming growth factor-beta1 on parathyroid hormone-related protein mRNA expression and protein secretion in canine prostate epithelial, stromal, and carcinoma cells.

BACKGROUND: Bone metastases of prostate carcinoma are associated with osteoblastic metastases. Tumor-derived factors, such as parathyroid hormone-related protein (PTHrP), may promote the development of osteoblastic metastases. We examined the effect of transforming growth factor-beta1 (TGF beta 1) on PTHrP mRNA expression and PTHrP secretion in normal canine prostate epithelial cells (PEC) and stromal cells (PSC), and in canine prostate carcinoma cells (PCC). METHODS: Primary cultures of PEC, PSC, and PCC were produced. The effect of TGF beta 1 on PTHrP mRNA expression was measured by Northern blot, and secretion of PTHrP into culture medium was measured by immunoradiometric assay (IRMA). Degradation of recombinant-human PTHrP (rhPTHrP) (1-84) inoculated in prostate cell cultures was measured over 24 hr. Arginine esterase (AE) activity in tissue and conditioned medium was also measured. RESULTS: TGF beta 1 increased PTHrP mRNA expression in a time- and dose-dependent manner in PEC and in PCC. TGF beta 1 decreased PTHrP mRNA in PSC. TGF beta 1 significantly increased PTHrP secretion (P < or = 0.05) into PEC but not PSC conditioned medium. rhPTHrP was significantly (P < or = 0.05) degraded in PEC conditioned medium as compared to PSC conditioned medium. AE activity was present in prostate and prostate carcinoma tissue, but not in conditioned medium from PEC or PSC. CONCLUSIONS: TGF beta 1 increased PTHrP mRNA expression in canine PEC and PCC, and decreased expression in PSC. This regulatory pathway may be important in the pathogenesis of osteoblastic metastases.