Zhen Zhang

Clostridium botulinum is a notorious pathogen that raises health and food safety concerns by producing the potent botulinum neurotoxin and causing botulism, a potentially fatal neuroparalytic disease in humans and animals. Efficient methods for the identification and isolation of C. botulinum are warranted for laboratory diagnostics of botulism and for food safety risk assessment. The cell wall binding domains (CBD) of phage lysins are recognized by their high specificity and affinity to distinct types of bacteria, which makes them promising for the development of diagnostic tools. We previously identified CBO1751, which is the first antibotulinal phage lysin showing a lytic activity against C. botulinum Group I. In this work, we assessed the host specificity of the CBD of CBO1751 and tested its feasibility as a probe for the specific isolation of C. botulinum Group I strains. We show that the CBO1751 CBD specifically binds to C. botulinum Group I sensu lato (including C. sporogenes) strains. We also demonstrate that some C. botulinum Group I strains possess an S-layer, the disruption of which by an acid glycine treatment is required for efficient binding of the CBO1751 CBD to the cells of these strains. We further developed CBO1751 CBD-based methods using flow cytometry and magnetic separation to specifically isolate viable cells of C. botulinum Group I. These methods present potential for applications in diagnostics and risk assessment in order to control the botulism hazard.

Cytotoxic necrotizing factor 1 (CNF1), a protein toxin produced by extraintestinal pathogenic Escherichia coli, activates the Rho-family small GTPases in eukaryotic cell, thereby perturbing multiple cellular functions. Increasing epidemiological evidence suggests a link between CNF1 and human inflammatory bowel disease and colorectal cancer. At the cellular level, CNF1 has been hypothesized to reprogram cell fate towards survival due to the role in perturbing cell cycle and apoptosis. However, it remains undetermined how cells survive from CNF1 intoxication. In this work, we show that CNF1 treatment blocks mitosis/cytokinesis, elicits endoreplication and polyploidisation in cultured human colon cancer cells, and drives them into reversible senescence, which provides a survival route for cells via depolyploidisation. Senescence in CNF1-treated cells is demonstrated with upregulation of several senescence markers including senescence-associated β-galactosidase activity, p53, p21 and p16, and concomitant inhibition of the retinoblastoma protein phosphorylation. Importantly, progeny derived from CNF1 treatment exhibit genomic instability exemplified by increased aneuploidy and become more resistant to CNF1, but not to 5-fluorouracil and oxaliplatin, the two agents commonly used in chemotherapeutic treatment for colorectal cancer. These observations display survival features of the cell after CNF1 treatment that may have implications for the potential role of CNF1 in carcinogenesis.

Background: Clinical presentations of paraneoplastic syndromes in neuroblastoma may multiply. Review of the clinical data and the literature on this syndrome may help in the diagnosis of neuroblastoma. Objectives: In order to make more accurate diagnosis, we reviewed the clinical data and the literature on this syndrome. Patients and Methods: Between April 2007 and April 2012, 68 children were diagnosed with neuroblastoma or ganglioneuroblastoma in our institution, 9 of which presented exclusively with paraneoplastic syndromes and were not treated with chemotherapy prior to diagnosis. After the diagnosis, all patients received chemotherapy and operation on NB97 protocol. Results: Among 68 pediatric patients with neuroblastoma or ganglioneuroblastoma, 4 (5.9%) patients suffered from neurological complications at diagnosis, 2 (2.9%) patients had digestive tract disorders, 2 (2.9%) patients had immune diseases, and 1 (1.5%) suffered from hematological disorder (without bone marrow involvement). All paraneoplastic syndrome patients achieved complete remission on paraneoplastic syndrome before completion of chemotherapy. Conclusions: Neuroblastoma may present with a range of non-specific neurologic symptoms in addition to the well-known opsoclonus-myoclonus syndrome and cerebellar ataxia. In any case, the presence of unexplained neurologic manifestations and other common clinical presentations such as rash, constipation, diarrhea, and especially immune disorders in an otherwise healthy child had raised the possibility of paraneoplastic syndrome due to the presence of an undiagnosed tumor. Keywords: Paraneoplastic Syndromes; Neuroblastoma; Child; Ganglioneuroblastoma; Nervous System Diseases

A collection of 36 Clostridium botulinum type E strains was examined by pulsed-field gel electrophoresis (PFGE) and Southern hybridization with probes targeted to botE and orfX1 in the neurotoxin gene cluster. Three strains were found to contain neurotoxin subtype E1 gene clusters in large plasmids of about 146 kb in size.