Photodynamic and Antibiotic Therapy Impair the Pathogenesis of Enterococcus faecium in a Whole Animal Insect Model

Enterococcus faecium has emerged as one of the most important pathogens in healthcare-associated infections worldwide due to its intrinsic and acquired resistance to many antibiotics, including vancomycin. Antimicrobial photodynamic therapy (aPDT) is an alternative therapeutic platform that is currently under investigation for the control and treatment of infections. PDT is based on the use of photoactive dye molecules, widely known as photosensitizer (PS). PS, upon irradiation with visible light, produces reactive oxygen species that can destroy lipids and proteins causing cell death. We employed Galleria mellonella (the greater wax moth) caterpillar fatally infected with E. faecium to develop an invertebrate host model system that can be used to study the antimicrobial PDT (alone or combined with antibiotics). In the establishment of infection by E. faecium in G. mellonella, we found that the G. mellonella death rate was dependent on the number of bacterial cells injected into the insect hemocoel and all E. faecium strains tested were capable of infecting and killing G. mellonella. Antibiotic treatment with ampicillin, gentamicin or the combination of ampicillin and gentamicin prolonged caterpillar survival infected by E. faecium (P = 0.0003, P = 0.0001 and P = 0.0001, respectively). In the study of antimicrobial PDT, we verified that methylene blue (MB) injected into the insect followed by whole body illumination prolonged the caterpillar survival (P = 0.0192). Interestingly, combination therapy of larvae infected with vancomycin-resistant E. faecium, with antimicrobial PDT followed by vancomycin, significantly prolonged the survival of the caterpillars when compared to either antimicrobial PDT (P = 0.0095) or vancomycin treatment alone (P = 0.0025), suggesting that the aPDT made the vancomycin resistant E. faecium strain more susceptible to vancomycin action. In summary, G. mellonella provides an invertebrate model host to study the antimicrobial PDT and to explore combinatorial aPDT-based treatments

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology

Cell proliferation of the duodenal mucosa in patients affected by familial adenomatous polyposis

BACKGROUND & AIMS: Patients affected by familial adenomatous polyposis (FAP) are at increased risk of developing duodenal adenomas. In this study, cell proliferation of duodenal mucosa was analyzed to detect kinetic abnormalities related to cancer risk. METHODS: Duodenal biopsy specimens were collected in three groups of patients: group A, 9 hospital controls; group B, 14 patients with FAP without duodenal adenomas; and group C, 6 patients with FAP and duodenal adenomas. Proliferative cell nuclear antigen was assessed through immunohistochemistry. The main labeling parameters were (1) overall labeling index (LI) and (2) LI in the upper 40% of the crypts. RESULTS: Overall LI in groups B and C was higher than in group A (both P < 0.01). LI in group C was also significantly higher than in group B (P < 0.01). Similarly, the upper 40% LI was higher in groups B and C than in group A (both P < 0.01). This value was higher in group C than in group B (P < 0.05). CONCLUSIONS: These data suggest the presence of cell kinetics abnormalities in FAP and the existence of two subgroups of patients with FAP at different risks of duodenal neoplasia. These abnormalities could be used as an intermediate biomarker for chemoprevention studies of duodenal cancer in FAP

Cell renewal and cancer risk of the stomach: Analysis of cell proliferation kinetics in atrophic gastritis

We examined cell proliferation kinetics of gastric mucosa in 28 patients affected by chronic atrophic gastritis by means of autohistoradiography of biopsies incubated with tritiated thymidine. The results have been compared with those obtained from 12 patients with normal gastric mucosa. In chronic atrophic gastritis, patients showed a proliferative pattern similar to controls. The remaining patients had an increased number of replicating cells together with an expansion of the proliferative compartment towards the surface of the mucosa. These results suggest that in chronic atrophic gastritis, as far as cell proliferation is concerned, two subgroups of patients with two different levels of risk of developing gastric cancer exist. The first one, showing an expansion of the proliferating area, probably is at higher risk. As a matter of fact, such an abnormality expresses an alteration of cell growth control similar to that observed in preneoplastic conditions of the colon and in gastric mucosa of animals treated with carcinogenic substances

RECTAL CELL-PROLIFERATION AND COLON CANCER RISK IN ULCERATIVE-COLITIS

Cell proliferation kinetics of 30 patients affected by extensive ulcerative colitis in remission have been studied with autoradiography of rectal biopsies incubated with tritiated thymidine. The results have been compared with those of 20 control subjects without evidence of colonic diseases, and of 16 patients with multiple nonfamilial colonic adenomas. The labeling index was similar in the three groups (P = NS). On the contrary, the labeling frequency (SEM) in the upper 40% of the crypt (phi h value) was 0.04 +/- 0.01 in controls, 0.16 +/- 0.02 in ulcerative colitis, and 0.10 +/- 0.01 in adenoma patients (P less than 0.001 ulcerative colitis versus controls, P less than 0.01 adenomas versus controls, P = NS ulcerative colitis versus adenomas). The distribution of phi h values in ulcerative colitis showed a bimodal trend with 22 patients having mean phi h values similar to adenoma patients (0.10 +/- 0.01) and 8 with higher values (0.30 +/- 0.02). No relationship was found between phi h values and duration of colitis, age of patients, or age at onset of symptoms. These data show that cell kinetics studies can detect patients at particularly high risk of colon cancer, and that additional factors should determine colon cancer risk level in ulcerative colitis