A Case of Intranasal Hemangioma and Concurrent Tetracycline-induced Ulcerative Gastritis in Dogs

Tracheal Hemangioma Causing Lung Emphysema and Pneumopericardium in a Rabbit—A Case Report

A pet rabbit (female, 8 years old, and mixed breed) with symptoms of dyspnea, apathy, and weight loss was treated for an acute respiratory infection. Due to the lack of improvement, it was referred to the Imaging Diagnostics Laboratory of the Department and Clinic of Surgery for a computer tomography scan of the thoracic cavity. The examination revealed the presence of air in the pericardial sac, a pneumopericardium, along with pulmonary emphysema. A few minutes after the examination, the rabbit developed circulatory and respiratory failure and died. Necropsy confirmed the presence of a pneumopericardium and pulmonary emphysema, and revealed, in the tracheal lumen, the presence of a tumor histologically consistent with hemangioma. A spontaneous pneumopericardium occurs when air from the respiratory system moves into the pericardial sac. This is the first case of the simultaneous occurrence of tracheal hemangioma and a pneumopericardium in a rabbit.

CORP: Using transgenic mice to study skeletal muscle physiology

The development of tissue-specific inducible transgenic mice has provided a powerful tool to study gene function and cell biology in almost any tissue of interest at any given time within the animal's life. The purpose of this review is to describe how to use two different inducible transgenic systems, the Cre-loxP system and the Tet-ON/OFF system, that can be used to study skeletal muscle physiology. Myofiber- and satellite cell-specific Cre-loxP transgenic mice are described as is how these mice can be used to knockout a gene of interest or to deplete satellite cells in adult skeletal muscle, respectively. A myofiber-specific Tet-ON system is described as is how such mice can be used to overexpress a gene of interest or to label myonuclei. How to effectively breed and genotype the transgenic mice are also described in detail. The hope is this review will provide the basic information necessary to facilitate the incorporation of tissue-specific inducible transgenic mice into a skeletal muscle research program.

Stability of Doxycycline in Feed and Water and Minimal Effective Doses in Tetracycline-Inducible Systems

Despite the extensive use of doxycycline in tetracycline-inducible rodent models, little is known regarding its stability in feed or water or the most effective route or dose. We assessed the concentrations of doxycycline in reverse-osmosis-purified (RO; pH 6.0) and acidified RO (pH 2.6) water in untinted or green-tinted bottles. Doxycycline remained stable in all groups for 7 d and in acidified water in untinted bottles for 14 d. Fungal growth occurred in nonacidified water in tinted and untinted bottles by 12 and 14 d, respectively, and in tinted bottles containing acidified water on day 14, but not in untinted bottles with acidified water. Doxycycline concentrations were also assessed before and at various points after the pelleting of feed from 2 vendors. Each batch was divided for storage at 4 °C, at room temperature, or within ventilated mouse isolator cages and then sampled monthly for 6 mo. Drying caused the greatest decline in doxycycline concentration, whereas γ-irradiation plus shipping and storage condition had minimal effect. Two mouse lines with tetracycline-inducible promoters received 25, 150, or 467 μg/mL or 2 mg/mL doxycycline in water and 200 or 625 ppm in feed before analysis of GFP expression. GFP was expressed in Rosa-rtTA2 mice at 150 μg/mL, whereas Cags-rtTA3 mice required 25 μg/mL. These studies indicate that 1) doxycycline-compounded feed can be handled in the same manner as standard rodent feed, 2) tinted water bottles are not necessary for maintaining drug concentrations, and 3) concentrations lower than those used typically may be effective in lines with tetracycline-inducible promoters.