Molecular Architecture of Salmonella Typhimurium Virus P22 Genome Ejection Machinery.

Bacteriophage P22 is a prototypical member of the Podoviridae superfamily. Since its discovery in 1952, P22 has become a paradigm for phage transduction and a model for icosahedral viral capsid assembly. Here, we describe the complete architecture of the P22 tail apparatus (gp1, gp4, gp10, gp9, and gp26) and the potential location and organization of P22 ejection proteins (gp7, gp20, and gp16), determined using cryo-EM localized reconstruction, genetic knockouts, and biochemical analysis. We found that the tail apparatus exists in two equivalent conformations, rotated by ∼6° relative to the capsid. Portal protomers make unique contacts with coat subunits in both conformations, explaining the 12:5 symmetry mismatch. The tail assembles around the hexameric tail hub (gp10), which folds into an interrupted ß-propeller characterized by an apical insertion domain. The tail hub connects proximally to the dodecameric portal protein and head-to-tail adapter (gp4), distally to the trimeric tail needle (gp26), and laterally to six trimeric tailspikes (gp9) that attach asymmetrically to gp10 insertion domain. Cryo-EM analysis of P22 mutants lacking the ejection proteins gp7 or gp20 and biochemical analysis of purified recombinant proteins suggest that gp7 and gp20 form a molecular complex associated with the tail apparatus via the portal protein barrel. We identified a putative signal transduction pathway from the tailspike to the tail needle, mediated by three flexible loops in the tail hub, that explains how lipopolysaccharide (LPS) is sufficient to trigger the ejection of the P22 DNA in vitro.

A structural dendrogram of the actinobacteriophage major capsid proteins provides important structural insights into the evolution of capsid stability.

Many double-stranded DNA viruses, including tailed bacteriophages (phages) and herpesviruses, use the HK97-fold in their major capsid protein to make the capsomers of the icosahedral viral capsid. After the genome packaging at near-crystalline densities, the capsid is subjected to a major expansion and stabilization step that allows it to withstand environmental stresses and internal high pressure. Several different mechanisms for stabilizing the capsid have been structurally characterized, but how these mechanisms have evolved is still not understood. Using cryo-EM structure determination of 10 capsids, structural comparisons, phylogenetic analyses, and Alphafold predictions, we have constructed a detailed structural dendrogram describing the evolution of capsid structural stability within the actinobacteriophages. We show that the actinobacteriophage major capsid proteins can be classified into 15 groups based upon their HK97-fold.

Simple scoring system for early management of heparin-induced thrombocytopenia.

This study was performed to develop a simple scoring system to aid in the early clinical management of patients suspected of heparin-induced thrombocytopenia (HIT) with regard to decisions for continued heparin therapy. The system was designed to arrive at low (0) or possible (1) probability scores without knowledge of laboratory test results (except platelet counts) to avoid delays. As the safest clinical approach is to discontinue heparin, intermediate and high scores were combined. Critically ill VA hospital patients (n = 100) with a ≥30% fall in platelet count were assessed by platelet aggregation (PA), (14)C-serotonin release assay ((14)C-SRA), and GTI ELISA. In this population, 53% were scored 1 and of these 43% were positive by laboratory test. Emphasizing the decision to discontinue heparin, the clinical signs of HIT were paramount for the immediate determination of a diagnosis of HIT without dependence on a positive laboratory test.

Alcohol misuse in older people: heavy consumption and protean presentations.

BACKGROUND: Alcohol misuse, especially binge drinking in young people, and alcoholic liver disease are major public health concerns. However, alcohol misuse in older people is underestimated and often goes undetected. OBJECTIVE: To document alcohol consumption and clinical presentation of alcohol misuse in hospital inpatients aged >or=60 years. METHODS: 208 inpatients aged >or=60 years, referred to the alcohol liaison nurse between 1998 and 2003 at the Royal Bolton Hospital, Bolton, UK, were assessed for sex, alcohol intake, primary and secondary reasons for admission, and other concurrent health problems and death. RESULTS: 90% of men drank >21 units weekly and 93% of women drank >14 units weekly. Median weekly alcohol intake was 78.5 units for men and 47 units for women. Acute intoxication, falls, circulatory problems and alcoholic liver disease were the main primary reasons for admission. Neglect or malnutrition, alcoholic liver disease and hypertension were the main secondary reasons and concurrent health problems. 30% of patients died between 1998 and 2003. CONCLUSION: In inpatients aged >or=60 years who were referred to the alcohol liaison nurse in a district general hospital, heavy alcohol consumption, often to very high levels, was characteristic in both men and women and was associated with a wide variety of primary and secondary clinical presentations, including death.

Reducing the risks of parenteral nutrition.

Parenteral nutrition is a vital method of delivering essential nutrients to some patients. But if used inappropriately it can increase the risk of catheter-related infection and incur unnecessary expense. Mary Bird explains how a nutritional support team's involvement transformed the quality of care for patients receiving the therapy at one trust.