Lung lobe torsion in association with a pulmonary papillary carcinoma in a dog.

Lung lobe torsion (LLT) is an uncommon condition in dogs reported to be most commonly idiopathic or secondary to trauma, pleural effusion, lung lobectomy or thoracic neoplasia. Carcinomas are the most common primary lung tumours in dogs, but only a few cases have been reported in association with LLT in veterinary medicine. This case describes an adult male neutered Labrador, which presented with lethargy, weight loss and pleural effusion. Computed tomography (CT), cytology of the lung, thoracocentesis and fluid analysis were performed. CT revealed pleural effusion and torsion of the left cranial lung lobe with no evidence of a pulmonary mass or metastatic disease. Thoracotomy and left cranial lung lobectomy were performed. Intraoperatively there was no macroscopic evidence of pulmonary neoplasia. Histopathology of the lobar tissue confirmed grade 2 pulmonary papillary carcinoma. It is possible that early detection and surgical management might help to prevent the morbidity and mortality associated with LLT. However, as in this case, the underlying cause for the LLT will ultimately determine the patient's prognosis. The final diagnosis of papillary carcinoma in this case, was only made via histopathological assessment of the pulmonary tissue as it was unclear on the advanced imaging and macroscopic intraoperative evaluation of the lungs. This case highlights the importance of considering pulmonary neoplasia as a differential for LLT even in the absence of a macroscopic mass, and therefore the value of performing histopathology on the excised lung tissue.

Photodynamic fungicidal efficacy of hypericin and dimethyl methylene blue against azole-resistant Candida albicans strains.

Antimicrobial photodynamic therapy (aPDT) is an emerging alternative to treat infections based on the use of photosensitisers (PSs) and visible light. To investigate the fungicidal effect of PDT against azole-resistant Candida albicans strains using two PSs with a different mechanism of action, hypericin (HYP) and 1,9-dimethyl methylene blue (DMMB), comparing their efficacy and the reactive oxygen species (ROS) species involved in their cytotoxicity. Azole-resistant and the azole-susceptible C. albicans strains were used. Solutions of 0.5 and 4 McFarland inoculum of each Candida strain were treated with different concentrations of each PS, and exposed to two light-emitting diode light fluences (18 and 37 J cm⁻²). Mechanistic insight was gained using several ROS quenchers. The minimal fungicidal concentration of HYP for ≥3 log10 CFU reduction (0.5 McFarland) was 0.62 µmol l⁻¹ for most strains, whereas for DMMB it ranged between 1.25 and 2.5 µmol l⁻¹. Increasing the fluence to 37 J cm⁻² allowed to reduce the DMMB concentration. Higher concentrations of both PSs were required to reach a 6 log10 reduction (4 McFarland). H2O2 was the main phototoxic species involved in the fungicidal effect of HYP-aPDT whereas ¹O2 was more important for DMMB-based treatments. aPDT with either HYP or DMMB is effective in killing of C. albicans strains independent of their azole resistance pattern. HYP was more efficient at low fungal concentration and DMMB at higher concentrations.