Radiology of the continent ileostomy reservoir: I. Method of examination and normal findings

The aim of the present study is to describe the radiologic methods used to study continent ileostomy reservoirs and to depict the normal radiologic features and variations identified by these procedures. During an 8-year period, 408 double-contrast studies were performed in 261 patients. The present study comprises 170 examinations in 99 patients with normal findings. A high-density barium contrast medium and air were used. Modest variation in the size and shape of the reservoirs was observed. The mucosal pattern of the reservoirs resembled that of the ileum but the folds were slightly wider. The continence-providing valves were 3–5 cm long and had a diameter of 2.5–4.0 cm. The diameter of the afferent ileal segments was usually slightly larger than that of more proximal ileal segments, with an upper limit of approximately 4 cm. The efferent ileal segments generally had a straight course without widening or outpouches. Retrograde barium double-contrast examination is a satisfactory method for the evaluation of continent ileostomy reservoirs. Here we define the range of normal variations of such reservoirs as seen on retrograde double-contrast radiologic examinations.     

Evaluation of clinical isolates of Pseudomonas aeruginosa for ribosomal resistance to tobramycin

The suggested use of tobramycin in selective decontamination of the digestive tract led to the investigation of the part played clinically by ribosomal resistance in Pseudomonas aeruginosa. Examination of 32 tobramycin-resistant isolates, both enzyme and non-enzyme producing, suggests that ribosomal resistance is clinically important.     

Thermal injury in pregnancy--the neglected tragedy

Thermal injury sustained during pregnancy presents special management problems for the gravid woman and her unborn child. Because of the reported high morbidity and mortality and lack of available data in South Africa, a multicentre retrospective review was undertaken by five burn centres. Thirty-three patients (average age 25,7 years) with mean 30% (range 1-80%) total body surface area burn were assessed. A review of the clinical material led to the following observations and conclusions. Pregnancy does not influence maternal outcome after thermal injury and maternal survival is usually accompanied by fetal survival in the absence of significant maternal complications. Maternal survival is less likely if the burn wound exceeds 50% total body surface area. Thermal injury does increase the risk of spontaneous abortion and premature labour, and fetal survival depends on fetal maturity. Early obstetric intervention is only indicated in the gravely ill patient where complications (hypoxia, hypotension, sepsis) jeopardize the life of a viable fetus. The mode of delivery should be determined by obstetric considerations.     

SARS associated coronavirus has a recombinant polymerase and coronaviruses have a history of host-shifting.

The sudden appearance and potential lethality of severe acute respiratory syndrome associated coronavirus (SARS-CoV) in humans has focused attention on understanding its origins. Here, we assess phylogenetic relationships for the SARS-CoV lineage as well as the history of host-species shifts for SARS-CoV and other coronaviruses. We used a Bayesian phylogenetic inference approach with sliding window analyses of three SARS-CoV proteins: RNA dependent RNA polymerase (RDRP), nucleocapsid (N) and spike (S). Conservation of RDRP allowed us to use a set of Arteriviridae taxa to root the Coronaviridae phylogeny. We found strong evidence for a recombination breakpoint within SARS-CoV RDRP, based on different, well supported trees for a 5' fragment (supporting SARS-CoV as sister to a clade including all other coronaviruses) and a 3' fragment (supporting SARS-CoV as sister to group three avian coronaviruses). These different topologies are statistically significant: the optimal 5' tree could be rejected for the 3' region, and the optimal 3' tree could be rejected for the 5' region. We did not find statistical evidence for recombination in analyses of N and S, as there is little signal to differentiate among alternative trees. Comparison of phylogenetic trees for 11 known host-species and 36 coronaviruses, representing coronavirus groups 1-3 and SARS-CoV, based on N showed statistical incongruence indicating multiple host-species shifts for coronaviruses. Inference of host-species associations is highly sensitive to sampling and must be considered cautiously. However, current sampling suggests host-species shifts between mouse and rat, chicken and turkey, mammals and manx shearwater, and humans and other mammals. The sister relationship between avian coronaviruses and the 3' RDRP fragment of SARS-CoV suggests an additional host-species shift. Demonstration of recombination in the SARS-CoV lineage indicates its potential for rapid unpredictable change, a potentially important challenge for public health management and for drug and vaccine development.     

Flickering fusion pores comparable with initial exocytotic pores occur in protein-free phospholipid bilayers

For the act of membrane fusion, there are two competing, mutually exclusive molecular models that differ in the structure of the initial pore, the pathway for ionic continuity between formerly separated volumes. Because biological “fusion pores” can be as small as ionic channels or gap junctions, one model posits a proteinaceous initial fusion pore. Because biological fusion pore conductance varies widely, another model proposes a lipidic initial pore. We have found pore opening and flickering during the fusion of protein-free phospholipid vesicles with planar phospholipid bilayers. Fusion pore formation appears to follow the coalescence of contacting monolayers to create a zone of hemifusion where continuity between the two adherent membranes is lipidic, but not aqueous. Hypotonic stress, causing tension in the vesicle membrane, promotes complete fusion. Pores closed soon after opening (flickering), and the distribution of fusion pore conductance appears similar to the distribution of initial fusion pores in biological fusion. Because small flickering pores can form in the absence of protein, the existence of small pores in biological fusion cannot be an argument in support of models based on proteinaceous pores. Rather, these results support the model of a lipidic fusion pore developing within a hemifused contact site.