Impact of wastewater from different sources on the prevalence of antimicrobial-resistant Escherichia coli in sewage treatment plants in South India.

The sewage treatment plant (STP) is one of the most important interfaces between the human population and the aquatic environment, leading to contamination of the latter by antimicrobial-resistant bacteria. To identify factors affecting the prevalence of antimicrobial-resistant bacteria, water samples were collected from three different STPs in South India. STP1 exclusively treats sewage generated by a domestic population. STP2 predominantly treats sewage generated by a domestic population with a mix of hospital effluent. STP3 treats effluents generated exclusively by a hospital. The water samples were collected between three intermediate treatment steps including equalization, aeration, and clarification, in addition to the outlet to assess the removal rates of bacteria as the effluent passed through the treatment plant. The samples were collected in three different seasons to study the effect of seasonal variation. Escherichia coli isolated from the water samples were tested for susceptibility to 12 antimicrobials. The results of logistic regression analysis suggest that the hospital wastewater inflow significantly increased the prevalence of antimicrobial-resistant E. coli, whereas the treatment processes and sampling seasons did not affect the prevalence of these isolates. A bias in the genotype distribution of E. coli was observed among the isolates obtained from STP3. In conclusion, hospital wastewaters should be carefully treated to prevent the contamination of Indian environment with antimicrobial-resistant bacteria.

Genetic analysis based on next generation sequencing of Streptococcus equi subsp. equi isolated from horses imported into Japan.

Strangles is a globally widespread, commonly diagnosed and important infectious disease of equids caused by Streptococcus equi subsp. equi. We performed whole genome sequencing of 19 S. equi isolates collected from imported horses at the Japanese border. Of these isolates, 15 isolates were obtained from clinical cases and 4 were from subclinical cases. The 19 isolates were grouped into 3 Bayesian analysis of population structure (BAPS) groups by the core genome single nucleotide polymorphism analysis corresponding to exporting country, SeM typing, or exporter of the horses. The 19 isolates possessed same pathogenic genes regardless of clinical status in imported horses and no antimicrobial resistance genes. The disease status of the horses may rather reflect the prior exposure of animals with sub-clinical infection to S. equi.

The inhibitory effect of connexin 32 gene on metastasis in renal cell carcinoma.

We have previously reported that connexin (Cx) 32 gene, a member of gap junctions, was specifically downregulated in human renal cell carcinoma (RCC) and it acts as a tumor suppressor against RCC. Because there is no standard therapy for advanced RCC, we investigated the anti-metastatic effect of Cx32 to seek a possibility of new RCC therapy. In this study, we used human metastatic RCC cell (Caki-1), and established Cx32-expressed cell clone (Caki-1T) or only mock-transfected cell clone (Caki-1W). For experimental production of metastases, the cells were injected into the lateral tail vein of SCID mice. Seventy days after inoculation, metastatic colonies were observed in Caki-1W inoculated group, though none of them were in Caki-1T inoculated group. The plasma VEGF concentration was significantly lower in Caki-1T group compared to Caki-1W group. To investigate where Cx32 effects on, we also tried in vitro analysis and found that the malignant phenotypes involving metastasis steps were significantly decreased in Caki-1T under hypoxia, a mimic condition of internal tumor environment. After hypoxia treatment, the protein level of HIF-2alpha, which plays main role for hypoxia adaptation, was observed to increase in Caki-1W, whereas no expression was observed in Caki-1T. We investigated the activation of Src, which is required for stabilization of HIF-2alpha, is suppressed in Caki-1T compared to Caki-1W. These results suggest that Cx32 inhibits hypoxia adaptation governed by HIF-2alpha, and this may help to reduce the metastasis of RCC cells.

Systemic Staphylococcus pseudintermedius infection in an arctic fox (Vulpes lagopus) with severe multifocal suppurative meningoencephalitis and nephritis.

A 2-year-female arctic fox (Vulpes lagopus) developed anorexia, dehydration, and emaciation during the quarantine period for importation from Norway, and died 17 days later. At necropsy, a fistula was observed on the left gluteal region, and the left eye, left brain, and kidneys were discolored. Histologically, severe diffuse suppurative meningoencephalitis and renal abscesses were detected. Numerous Gram-positive cocci were detected in these lesions. Multidrug-susceptible Staphylococcus pseudintermedius were isolated from the lesions. These results suggest that S. pseudintermedius can cause severe multifocal suppurative meningoencephalitis and nephritis in foxes. This is the first report of multidrug-susceptible S. pseudintermedius meningoencephalitis and nephritis in a fox.

Peroxisome proliferator-activated receptor delta as a molecular target to regulate lung cancer cell growth.

It has been assumed that prostaglandin (PG)I2 signaling contributes to the negative growth control of lung cancer cells; however, the mechanism remains unresolved. PGI2 functions through a cell surface G protein-coupled receptor (prostaglandin I2-binding receptor, IP) and also exerts an effect by interacting with a nuclear hormone receptor, peroxisome proliferator-activated receptor delta (PPARdelta). We found that PPARdelta was a key molecule of PGI2 signaling to give negative growth control of lung cancer cells (A549), using carbarprostacyclin, a PGI2 agonist for IP and PPARdelta, and L-165041, a PPARdelta agonist. Furthermore, PPARdelta-induced cell growth control was reinforced by the inhibition of cyclooxygenase. These results suggest that PPARdelta activation under the suppression of PG synthesis is important to regulate lung cancer cell growth.

Connexin 32 potentiates vinblastine-induced cytotoxicity in renal cell carcinoma cells.

We have reported that connexin (Cx) 32 gene, a member of gap junction protein family, acts as a tumor suppressor gene in human renal cell carcinoma (RCC). Of solid tumors, RCC is one of the most chemoresistant cancers, and there is no effective cancer chemotherapy against RCC at present. In this study, we examined if the combination of Cx32-dependent tumor-suppressive effect and vinblastine (VBL), a chemotherapeutic agent which has been utilized for clinical RCC treatment, could be effective in enhancing the sensitivity of RCC to VBL treatment. Cx32 expression in a human metastatic RCC cell (Caki-1 cell) significantly enhanced in vitro and in vivo VBL-induced cytotoxicity on the cell. Cx32 expression in the RCC cells potentiated VBL-induced apoptosis compared to the Cx32-negative RCC cells in vitro as well as in vivo. The enhancing apoptosis in the RCC cells by Cx32 mainly depended on the decrease of P-glycoprotein (P-gp), a multidrug resistance gene-1 (MDR-1) product responsible for reduction of VBL accumulation into the cells. We also observed that silencing of Cx32 by short interfering RNA (siRNA) treatment elevated the level of P-gp in Caki-1 cells and that inhibition of P-gp function enhanced VBL-induced apoptosis in the RCC cells. These results suggest that Cx32 is effective to enhance VBL-induced cytotoxicity in Caki-1 cells via the reduction of P-gp. Overall, it seems that the combination of Cx32-dependent tumor-suppressive effect and VBL is promising as a new cancer therapy against RCC.

Contribution of the Src family of kinases to the appearance of malignant phenotypes in renal cancer cells.

Although the constitute activation of the Src family of kinases (Src) has been established as a poor prognostic factor in several types of cancer, the role of Src in renal cell carcinoma (RCC) has not been defined. This study aimed to determine whether Src could contribute to the appearance of malignant phenotypes in RCC. The role of Src in the appearance of malignant phenotypes in RCC was examined in two human renal cancer cell lines, Caki-1 from human metastatic RCC and ACHN from human primary RCC. Src activity in Caki-1 cells was higher than that in ACHN cells, and this difference corresponded to the difference of PP1 (a Src family inhibitor)-induced cytotoxicity on the two cells. The difference in cytotoxicity between the cells did not depend on cell cycle regulation but on the induction of apoptosis, and the difference in apoptosis particularly related to the reduction of the Bcl-xL level. Furthermore, in Caki-1 cells with higher Src activity, Src stimulated the production of vascular endothelial growth factor (VEGF), partially via the activation of Stat3, and the inhibition of Src activity caused a reduction of the VEGF level in serum, angiogenesis, and tumor development in a xenograft model. These results suggested that Src contributed to the appearance of malignant phenotypes in renal cancer cells, particularly due to the resistance against apoptosis by Bcl-xL and angiogenesis stimulated by Src-Stat3-VEGF signaling.