It is well known that bone mass density decreases with age. Age-related bone mass loss is ascribed to several factors. Nonenzymatic glycation has been proposed as a new potential factor in the loss of bone during aging. In this study we evaluated the concentration of pentosidine, an advanced glycation end product, in cortical and trabecular bone and in the plasma of subjects undergoing orthopedic surgery. The relationship between these parameters and a clinical index of osteoporosis was also studied. Samples of bone and plasma of 104 nondiabetic subjects (74 women and 30 men), 72 +/- 1 years old, were studied. Pentosidine was determined by HPLC after decalcification and hydrolysis. The radiologic Singh index was evaluated blindly by orthopedic surgeons to provide the degree of osteoporosis. Pentosidine concentration of cortical bone shows a significant exponential increase with age (r = 0.610, P < 0.001). This increase, however, is not seen in the trabecular bone, which is characterized by a large spread in the data. Interestingly the concentration of cortical pentosidine is also related to the Singh score (r(s) = -0.274, P < 0.01). Plasma pentosidine has a significant exponential correlation with age (r = +0.339, P < 0.001) and a linear correlation with the cortical bone pentosidine (r = +0.248, P < 0.05). This study demonstrates that pentosidine increases exponentially in cortical bone during aging, and is thus a good biomarker for the degree of bone mass density loss. The trabecular bone concentration of pentosidine is more variable, probably because of the turnover rate and the local environment; plasma pentosidine might provide information on the bone turnover rate.

Published studies, taken together, suggest the existence of a single canine lymphoma entity, with a small clear cell appearance by cytological evaluation, a histopathological T-zone pattern and an aberrant CD45-negative T-cell phenotype, mostly characterized by long-term survival. We describe clinical presentation and outcome in a retrospective case series of canine small clear cell/T-zone lymphoma. Despite the reported predisposition of Golden retriever, this breed was not represented in our case series. Most dogs presented with stage V disease, whereas only few had clinical signs or peripheral cytopenias. Blood was almost always more infiltrated than bone marrow. Median survival confirmed the favourable prognosis described in literature, but a few dogs died within a short time. Also, a subgroup of dogs developed second malignancies, eventually leading to death. We did not investigate possible prognostic factors because of the wide variety in treatments, and further studies are needed to identify high-risk animals.

Histopathology and immunohistochemistry are mandatory to solve the differential between canine low-grade lymphoma and reactive hyperplasia. However, clinicians and owners often show reluctance toward these invasive tests. However, molecular biology techniques are still not sensitive and specific enough to be regarded as a reliable tool for final diagnosis. In humans, flow cytometry (FC) allows a definitive diagnosis of T-cell lymphoma based on high prevalence of antigen aberrancies. We describe here the immunophenotype of 26 cases of suspect canine small-clear cell lymphoma, determined by multi-colour FC. All cases showed antigen aberrancies and therefore neoplasia was always confirmed. As a consequence, we argue that the combined use of cytology and FC allows solving the differential diagnosis between small clear cell lymphoma and non-neoplastic reactive conditions when histopathology is not available. Further studies are needed to establish if any aberrancy can be considered indicative of specific histotypes.

Ki67 can discriminate between high- and low-grade canine lymphomas, but its prognostic role in specific subtypes of the neoplasm is unknown. We assessed the prognostic significance of Ki67% (percentage of Ki67-positive cells), evaluated by flow cytometry, in 40 dogs with high-grade B-cell lymphoma, treated with a modified Wisconsin-Madison protocol (UW-25). The following variables were investigated for association with lymphoma specific survival (LSS) and relapse free interval (RFI): Ki67%, breed, sex, age, stage, substage, complete remission (CR). By multivariate analysis, Ki67% (P = 0.009) and achievement of CR (P = 0.001) were independent prognostic factors for LSS. Dogs with intermediate Ki67% (20.1-40%) presented longer LSS and RFI (median = 866 and 428 days, respectively) than dogs with low (median = 42 days, P < 0.001; median = 159 days, P = 0.014) or high (median = 173 days, P = 0.038; median = 100 days, P = 0.126) values. Determination of Ki67 is a prognostic tool that improves the clinical usefulness of flow cytometric analysis in canine high-grade B-cell lymphoma.

Ki67 is a nuclear antigen significantly correlated with degree of malignancy in human non-Hodgkin lymphomas. We wanted to assess the ability of flow cytometric evaluation of Ki67 index (Ki67I) in differentiating the grade of malignancy in canine lymphomas. Ki67I was determined on lymph node aspirates of 90 immunophenotyped lymphomas classified according to the updated Kiel classification: 80 high grade (HG, 62 B cell and 18 T cell) and 10 low grade (LG, 3 B cell and 7 T cell) lymphomas. HG lymphomas showed significantly higher Ki67I compared with LG lymphomas (P < 0.0001). A significant difference in HG lymphomas was detected between B- and T-immunophenotypes. Receiver operating characteristic (ROC) curve highlighted a high accuracy of Ki67I in recognizing HG lymphomas [area under the curve (AUC) = 99.4] and a cut-off value of 12.2% was established (sensitivity = 96.3% and specificity = 100%). Thus, we suggest the combination of Ki67I flow cytometric determination and immunophenotype as a reliable tool to classify canine lymphomas.