Genetic and physical analysis of the bacteriophage P22 tail protein

A plasmid based genetic system was developed for the tail protein of the Salmonella typhimurium bacteriophage P22 and used to isolate and characterize tail protein mutants. The tail protein is a trimeric structural protein of the phage and an endorhamnosidase whose activity is essential for infection. The gene for the tail protein has previously been cloned into a plasmid expression vector and sequenced. A plate complementation assay for tail protein produced from the cloned gene was developed and used to isolate 27 tail protein mutants following mutagenesis of the cloned gene. These mutations were mapped into 12 deletion intervals using deletions which were made on plasmids in vitro and crossed onto P22. The base substitutions were determined by DNA sequencing. The majority of mutants had missense or nonsense mutations in the protein coding portion of the gene; however four of the mutants were in the putative transcription terminator. The oligomeric state of tail protein from the 15 missense mutants was investigated using SDS and nondenaturing polyacrylamide gel electrophoresis of cell lysates. Wild-type tail protein retains its trimeric structure in SDS gels at room temperature. Two of the mutant proteins also migrated as trimers in SDS gels, yet one of these had a considerably faster mobility than wild-type trimer. Its migration was the same as wild-type in a nondenaturing gel, so it is thought to be a trimer which is partially denatured by SDS. Four of the mutants produced proteins which migrate at the position of a monomer in an SDS gel but cannot be seen on a nondenaturing gel. These proteins are thought to be either monomers or soluble aggregates which cannot enter the nondenaturing gel. The remainder of mutants produce protein which is degraded. The mutant tail protein which had normal trimeric mobility on SDS and nondenaturing gels was purified. This protein has essentially wild-type ability to attach to phage capsids, but its endorhamnosidase activity is only 4% of wild-type. ^

A critical review: Why isn't "cold pasteurization" being used widespread as a method to prevent food-related illnesses as a result of the consumption of ready-to-eat, fresh fruits, and vegetables

The Centers for Disease Control estimates that foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. The American public is becoming more health conscious and there has been an increase in the dietary intake of fresh fruits and vegetables. Affluence and demand for convenience has allowed consumers to opt for pre-processed packaged fresh fruits and vegetables. These pre-processed foods are considered Ready-to-Eat. They have many of the advantages of fresh produce without the inconvenience of processing at home. After seeing a decline in food-related illnesses between 1996 and 2004, due to an improvement in meat and poultry safety, tainted produce has tilted the numbers back. This has resulted in none of the Healthy People 2010 targets for food-related illness reduction being reached. Irradiation has been shown to be effective in eliminating many of the foodborne pathogens. The application of irradiation as a food safety treatment has been widely endorsed by many of the major associations involved with food safety and public health. Despite these endorsements there has been very little use of this technology to date for reducing the disease burden associated with the consumption of these products. A review of the available literature since the passage of the 1996 Food Quality Protection Act was conducted on the barriers to implementing irradiation as a food safety process for fresh fruits and vegetables. The impediments to adopting widespread utilization of irradiation food processing as a food safety measure involve a complex array of legislative, regulatory, industry, and consumer issues. The FDA’s approval process limits the expansion of the list of foods approved for the application of irradiation as a food safety process. There is also a lack of capacity within the industry to meet the needs of a geographically dispersed industry.^

A practice-based culminating experience with Texas Children's Hospital: A hospital's journey to baby-friendly status

Breastfeeding and the use of human milk are widely accepted as the most complete form of nutrition for infants. Breastfeeding is shown to be associated with many positive health outcomes for both infants and mothers. Healthy People 2000 goals to increase breastfeeding rates in the early postpartum period to 75% fell short, with only 64% of mothers meeting this objective. Lack of support from healthcare providers, and unsupportive hospital policies and practices are noted as barriers to the initiation and duration of breastfeeding. The purpose of this study was to evaluate implementation of the BFHI Ten Steps to Successful Breastfeeding at Texas Children's Hospital. ^ The Baby-Friendly Hospital Initiative (BFHI) was developed in 1991 by the World Health Organization and the United Nations Children's Fund (UNICEF) to ensure that healthcare facilities offering maternity services adhere to the Ten Steps of Successful Breastfeeding and the International Code of Marketing of Breast-Milk Substitutes, and create legislation to protect the rights of breastfeeding women. The instrument used in this study was the BFHI 100 Assessment Tool created by Dr. Laura Haiek, Director of Public Health in Monteregie, Quebec, and her staff at Health and Social Services Agency of Quebec. The BFHI 100 tool utilizes 100 different indicators of compliance with BFHI through questionnaires administered to staff and administrators, pregnant and postpartum mothers, and an observer. ^ The study concluded that although there is much room for improvement in educating breastfeeding mothers, overall, the mothers interviewed were satisfied with their level of care in regards to breastfeeding support. Areas of improvement include staff training, as some nursing staff admitted to relying on the lactation consultants to provide most of the breastfeeding education for mothers. Only a small percentage of mothers interviewed reported that their baby “roomed-in” on average of 22 hours per day during their hospital stay. Staff encouragement of the rooming-in practice will help to increase the proportion of mothers who allow their babies to room-in. The current breastfeeding policy will also need to be revised and strengthened to be compliant with the Ten Steps. Ideally, Baby-Friendly practices will become the norm after staff are trained and policy revisions are made. Staff training and acceptance of breastfeeding as optimal nutrition for infants are the most critical factors that will ultimately drive change for the organization. ^