No abstract

SARS-CoV-2 emerged in Wuhan in December 2019 and has caused the pandemic respiratory disease, COVID-19. Following what is presumed to be an initial zoonotic transmission event, the virus is now spreading efficient in humans. Very little is known about the susceptibility of domestic mammals kept as pets to this virus. Samples were collected over a 13-day period from a 17 year-old neutered male Pomeranian in Hong Kong SA that was taken into isolation after two members of the household tested positive for the virus. Nasal swabs were consistently positive on the five occasions the dog was tested using quantitative RT- PCR with viral loads between 7.5xE2 to 2.6 x10E4 RNA copies per mL of sample. The dog remained asymptomatic. Cultures attempted on three RT-PCR positive nasal samples were negative. Gene sequences from samples from two household members were identical. The viral sequence from the dog differed at three nucleotide positions; two of these resulted in amino acid changes but their significance is yet to be determined. Seroconversion was not detected but this was expected given the asymptomatic infection and low virus load. The evidence suggests that this is an instance of human-to-animal transmission of SARS-COV-2. It is likely that we could see similar events in other infected households. We do not have information yet on whether this virus can cause illness in dogs but no specific signs were seen in this dog. Whether infected dogs could transmit the virus to other animals or back to humans remains unknown. In this case it did not appear to have occurred.

Objective: Selective uptake and retention of haematoporphyrin derivative (HpD) in tumour tissue, especially at brain adjacent to the tumour (BAT) region, is an important factor in determining the efficacy of photodynamic therapy (PDT). The uptake and distribution of HpD was studied in 10 patients with malignant glioma. Method: Five cases were injected with HpD intravenously at a dose of 5 mg/kg bodyweight. Another five cases were injected with 10 mg (2 mL) HpD by ultrasound guidance into the tumour centre. After 24 h, the patients underwent craniotomy for tumour debulking. Biopsies of the tumour tissue and BAT region were sent for analysis. Results: In the intravenous administration group, the mean HpD level in the tumour centre was 2.0 ± 0.7 mg/g, which was lower than the level of HpD in the BAT region (3.6 ± 2.3 mg/g; P > 0.05). However, in the intratumoral injection group, the level of HpD was much higher in the tumour centre than in the BAT (4.7 ± 3.2 mg/g vs 1.4 ± 0.4 mg/g; P < 0.05). Fluorescence microscopy observations showed that HpD was distributed unevenly at the periphery of the blood vessels and stroma in the intravenous group. Bright and patchy distribution of HpD was also seen in the tumour centre after direct intratumoral injection. Intracellular uptake of HpD could be observed in the BAT region of both groups. Further study with a confocal laser scanning microscope (CLSM) provided evidence that HpD was localized intracellularly. Conclusion:The study showed that conventional intravenous administration of HpD can achieve a higher level in the BAT region, but the distribution of HpD varied and was unpredictable. Intratumoral injection can achieve a much higher HpD in the tumour centre; however, the distribution in the BAT region is unsatisfactory because of the irregular shape of the tumour mass. Taking into account this variable result, the HpD level may need to be tailored to meet each individual patient's requirement.