Mechanistic insight into Myc stabilization in breast cancer involving aberrant Axin1 expression.

High expression of the oncoprotein Myc has been linked to poor outcome in human tumors. Although MYC gene amplification and translocations have been observed, this can explain Myc overexpression in only a subset of human tumors. Myc expression is in part controlled by its protein stability, which can be regulated by phosphorylation at threonine 58 (T58) and serine 62 (S62). We now report that Myc protein stability is increased in a number of breast cancer cell lines and this correlates with increased phosphorylation at S62 and decreased phosphorylation at T58. Moreover, we find this same shift in phosphorylation in primary breast cancers. The signaling cascade that controls phosphorylation at T58 and S62 is coordinated by the scaffold protein Axin1. We therefore examined Axin1 in breast cancer and report decreased AXIN1 expression and a shift in the ratio of expression of two naturally occurring AXIN1 splice variants. We demonstrate that this contributes to increased Myc protein stability, altered phosphorylation at S62 and T58, and increased oncogenic activity of Myc in breast cancer. Thus, our results reveal an important mode of Myc activation in human breast cancer and a mechanism contributing to Myc deregulation involving unique insight into inactivation of the Axin1 tumor suppressor in breast cancer.

Clostridium difficile in retail meat and processing plants in Texas.

The incidence and severity of disease associated with toxigenic Clostridium difficile have increased in hospitals in North America from the emergence of newer, more virulent strains. Toxigenic C. difficile has been isolated from food animals and retail meat with potential implications of transfer to human beings. The objective of the present study was to determine the prevalence of C. difficile in pork from sausage manufacturing plants and retail meat in Texas. Twenty-three C. difficile isolates were detected from 243 meat samples (9.5%) from 3 sausage-manufacturing plants and 5 retail meat outlets from 2004 to 2009. Twenty-two isolates were positive for toxins A, B, and binary toxin, and were characterized as toxinotype V, PFGE type-NAP7, or "NAP7-variant." Susceptibilities to 11 antimicrobial agents in the current study were similar to those reported previously for toxinotype V isolates, although the results suggested somewhat reduced resistance than reported for other meat, animal, or human clinical toxinotype V isolates.

Clostridium difficile in poultry and poultry meat.

The incidence and severity of disease associated with toxigenic Clostridium difficile have increased in hospitals in North America from the emergence of newer, more virulent strains. Toxigenic C. difficile has been isolated from food animals and retail meat with potential implications of transfer to human beings. The objective of the present study was to determine the prevalence of toxigenic C. difficile in chickens and retail poultry meat in Texas. Seven C. difficile isolates were detected in fecal samples of 300 (2.3%) broiler chickens. Three cultivation procedures were evaluated for isolation of C. difficile from poultry meat and detected 1/32 (3.1%), 2/32 (6.2%), and 4/32 (12.5%) for the three procedures, respectively. Chicken and poultry meat isolates were characterized as toxinotype V and pulsed-field gel electrophoresis gel type-NAP7 or NAP7-variant. Susceptibilities to 11 antimicrobial agents in the current study suggested somewhat reduced resistance than reported for other meat or animal toxinotype V isolates.

Denaturing gradient gel electrophoresis as a tool to determine batch similarity of probiotic cultures of porcine cecal bacteria.

A continuous-flow porcine cecal bacterial culture has been used experimentally as treatment against enterotoxigenic Escherichia coli in weanling pigs. Periodically, the cultures must be started from frozen stock. Our results indicate that denaturing gradient gel electrophoresis can be applied as an indirect indication of culture similarity for each new batch generated from frozen stock.

Inoculation of Broiler Chicks with a Continuous-Flow Derived Bacterial Culture Facilitates Early Cecal Bacterial Colonization and Increases Resistance to Salmonella typhimurium.

Experiments were conducted to examine the effect of a continuous-flow (CF) derived bacterial culture and of dietary lactose on colonization level by anaerobic bacteria in the ceca of broiler chicks. Cecal facultative and strictly anaerobic bacteria colony forming units (CFU), total volatile fatty acid (TVFA), lactic and propionic acid concentrations in 3-d-old chicks, and cecal log10 Salmonella typhimurium colonization and propionic acid concentrations in 10-d-old chicks were measured. Treatment groups were control diet, 2% lactose diet, CF culture + control diet, and CF culture + 2% lactose diet. Groups inoculated with CF culture had decreased (P < 0.05) Salmonella in cecal contents at 10 d of age. The level of Salmonella protection was significantly (P < 0.05) correlated with increased cecal bacteria CFU, TVFA, and propionic acid concentrations in 3-d-old chicks. Results indicated that inoculating newly hatched chicks with CF culture containing cecal microflora originally obtained from adult chickens, facilitates early cecal colonization by native cecal microflora, and this is associated with protection against Salmonella .

Inhibition of Salmonella enteritidis Cecal and Organ Colonization in Leghorn Chicks by a Defined Culture of Cecal Bacteria and Dietary Lactose 1.

The effect of oral inoculation with a defined culture of cecal bacteria and provision of dietary lactose on colonization resistance to invasive Salmonella enteritidis was evaluated in leghorn chicks. A defined mixed culture composed of 11 indigenous cecal bacteria capable of utilizing lactose or lactose fermentation products as a primary carbon source was isolated and maintained in continuous-flow culture. Combined treatment with the defined culture and dietary lactose significantly decreased (P < 0.01) the number of Salmonella in the cecal contents and the number of Salmonella cecal-culture-positive chicks in four replicated trials. Additionally, Salmonella colonization of the spleen, liver, and cecal tonsils was significantly decreased (P < 0.05) in each of the trials. The results indicate that the resistance of leghorn chicks to S. enteritidis cecal and organ colonization is effectively increased by inoculation with a defined culture of cecal bacteria and provision of lactose in the diet.

In Vitro Inhibition of the Growth of Salmonella typhimurium and Escherichia coli 0157:H7 by Bacteria Isolated from the Cecal Contents of Adult Chickens.

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella .