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Tamoxifen, an estrogen receptor antagonist, has been clinically used as an antitumor drug and induces apoptosis in GH3 pituitary cells. Although di-(2-ethylhexyl) phthalate (DEHP) is a well-known environmental estrogen and the exposure to this chemical is well expected, reports are limited regarding effects of DEHP on tamoxifen-induced apoptosis in pituitary cells. In the cytotoxicity assay, the reduced cell viability in tamoxifen-treated GH3 cells was reversed by DEHP (250 microM) treatment for 4 days. To characterize cell death, cells were stained using Hoechst 33258. Apoptotic morphological change such as chromatin condensation induced by tamoxifen was suppressed by treatment with DEHP. Flow cytometric analysis revealed that the number of apoptotic cells induced by tamoxifen was significantly decreased by DEHP treatment. Enhanced poly (ADP-ribose) polymerase (PARP) cleavage by tamoxifen treatment was also inhibited by DEHP. These results suggest that DEHP suppresses tamoxifen-induced apoptosis in association with its estrogenic effect in GH3 cells and might counteract the therapeutic effect of tamoxifen.

Background: Plasma N-terminal pro-atrial natriuretic peptide (NT-proANP) and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations may be affected by the hydration status. Aim: This study aimed to evaluate the effect of dehydration on plasma NT-proANP and NT-proBNP concentrations in healthy dogs. Methods: This prospective study included five clinically healthy dogs. Furosemide was administered intravenously at 2–4 mg/kg every 1–2 h until completion of the dehydration model. The dehydration model was considered complete when weight loss was ≥5% and findings of dehydration on physical examination were observed. Plasma NT-proANP and NT-proBNP concentrations were compared at three time points: before the dehydration model was created (point 1), at the completion of the dehydration model (point 2), and when dehydration was judged to have improved (point 3). Association between plasma NT-proANP and NT-proBNP concentrations, and each clinical variable (physical examination, blood pressure, blood chemistry, blood gases, and echocardiography) was assessed using linear regression analysis. Results: Plasma NT-proANP concentration decreased significantly from point 2 to point 1 (p < 0.05), whereas plasma NT-proBNP concentration showed a decreasing trend but did not differ significantly between points 1 and 2. Plasma NT-proANP concentration correlated significantly with body weight (R2 = 0.178) and plasma NT-proBNP concentration (R2 = 0.284) (p < 0.05, respectively), and plasma NT-proBNP concentration correlated significantly with electrolytes (sodium, R2 = 0.439; potassium, R2 = 0.444; chloride, R2 = 0.419), and echocardiographic parameters (diastolic left ventricular internal diameter [LVIDd], R2 = 0.519; weight-standardised LVIDd, R2 = 0.535) (p < 0.01, respectively). Conclusion: The plasma NT-proANP concentrations decreased with dehydration. However, the plasma NT-proBNP concentration did not change with mild dehydration and reflected left ventricular morphology.

A urethrorectal fistula is a rare congenital or acquired condition in dogs. Its treatment has been reported through a perineal incision, but not through a rectal mucosal approach. A 10‐month‐old, entire, male French bulldog was presented with leakage of urine from the rectum and urethra during urination, which was diagnosed as urethrorectal fistula by computed tomography, and surgery was performed. In our case, a rectal mucosal approach was used instead of a perineal approach, which has been reported previously. Postoperatively, the fistula tract was completely blocked and treatment was successful. Most treatment of urethrorectal fistulas involves excision of the fistula tube or urinary diversion, but the surgical approach should be considered depending on the location of the fistula. Because the perineum contains more important nerves and muscles related to defecation than the rectal mucosa, the rectal mucosal approach minimizes damage to muscles and nerves and reduces complications.

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