The emerging diversity of the electrophoretic types of Vibrio cholerae in the Western Hemisphere

Since the Latin American cholera epidemic began in 1991, 447 isolates of Vibrio cholerae O1 from the Western Hemisphere have been assayed by multilocus enzyme electrophoresis (MEE) to determine allelic variation among 16 enzyme-encoding genes. Two electrophoretic types (ETs) were identified among toxigenic isolates from Latin America: 323 were ET 4, the ET associated with the Latin American epidemic, and 29 were ET 3. Twenty-three of these ET 3 isolates had a distinctive antimicrobial resistance pattern also seen in isolates imported into the United States from Latin America and Southeast Asia. These resistant isolates had an identical ribotype and nearly identical pulsed-field gel electrophoresis (PFGE) patterns. Most nontoxigenic isolates analyzed were not precursors or descendants of toxigenic epidemic strains. MEE provided a population genetic frame-work for the interpretation of PFGE and ribotype data from the isolates in this study. All three methods identified 2 distinct strains of toxigenic V. cholerae O1 currently epidemic in Latin America.     

Contact activation during incubation of five different polyurethanes or glass in plasma

During blood-material interaction, the enzymes factor XII fragment (factor XIIf) and kallikrein are generated (contact activation). In this study, the enzymatic activities of factor XIIf and kallikrein were examined with an assay based on the conversion of tripeptide-p-nitroanilide substrate. With the use of aprotinin to inhibit kallikrein, the proteolytic activities of factor XIIf and kallikrein could be separately determined. In this in vitro study, two commercially available polyurethanes, Pellethane and Biomer; three custom synthesized polyurethanes; a biomerlike 2000 MW polytetramethyleneoxide containing polyurethane (PU-2000); an octadecyl extended (ODCE) biomer-like 2000 MW polytetramethyleneoxide containing polyurethane (PU-2000-ODCE); a hard-segment polyurethane (HS-PU); and glass (reference material) were incubated in 25% diluted plasma. In both series of experiments, glass caused the highest amidolytic activities by factor XIIf and kallikrein compared with any of the polyurethanes. In contrast, within the polyurethane group of materials, lower amidolytic activities by factor XIIf and kallikrein were measured on the custom-made polyurethanes than on the commercially available polyurethanes, although the differences among the polyurethanes were small. In addition, the influence of different ratios of material surface to the plasma incubation volume was studied. An increased ratio of surface area over plasma volume resulted in reduced contact activation, suggesting that plasma components are the limiting factor.     

Bedwetting and psychopathology in adolescents

OBJECTIVE: To document the incidence, source, and reasons for all complaints received by a large municipal emergency medical services (EMS) program. METHODS: A retrospective review of all complaints received during three consecutive years (1990-1992) in a centralized EMS system serving a large municipality (population 2 million). All cases were categorized by year, source, and nature of the complaint. RESULTS: In the three study years, EMS responded to 416,892 incidents with nearly a half-million patient contacts. Concurrently, 371 complaints were received (incidence of 1.12 per thousand); 132 in 1990, 129 in 1991, and 110 in 1992. Most complaints involved either: 1) allegations of "rude or unprofessional conduct" (34%), 2) "didn't take patient to the hospital" (19%), or 3) "problems with medical treatment" (13%). Only 1.6% (n = 6) were response-time complaints. Other complaints included "lost/damaged property," "taken to the wrong hospital," "inappropriate billing," and "poor driving habits." The most common sources were patient's families (39%) and the patients themselves (30%). Only 7.8% were from health care providers. CONCLUSION: Reviews of complaints provide information regarding EMS system performance and reveal targets for quality improvement. For the EMS system examined, this study suggests a future training focus on interpersonal skills and heightened sensitivities, not only toward patients, but also toward bystanders and family members.     

A case-control study of traffic risk factors and child pedestrian injury

BACKGROUND: Pedestrian injuries in children constitute an important cause of mortality and morbidity. Specific hazards which contribute to these injuries need to be identified to enable the development of preventive strategies. METHODS: A population-based case-control study was conducted in which 40 aspects of traffic and road environment that contribute to the likelihood of childhood pedestrian injury were examined. The factors of interest were measured at 100 places of injury and 200 control sites between December 1991 and December 1993. RESULTS: The volume of traffic (odds ratio [OR] = 2.16 for an increase of 100 vehicles per hour) in combination with the proportion of vehicles exceeding the speed limit (OR = 1.04) for each 1% increase in average speed, and the presence of footpaths (OR = 11.0) were associated with significant increase in the risk of injury. A graded inverse relationship was present between socioeconomic status and the odds of pedestrian injury. CONCLUSIONS: These findings have obvious implications for public health as features of the physical environment are potentially modifiable.     

Cell recognition, signal induction, and symmetrical gene activation at the dorsal-ventral boundary of the developing Drosophila wing

Appendage formation in insects and vertebrates depends upon signals from both the anterior-posterior and dorsal-ventral (DV) axes. In Drosophila, wing formation is organized symmetrically around the DV boundary of the growing wing imaginal disc and requires interactions between dorsal and ventral cells. Compartmentalization of the wing disc, dorsal cell behavior, and the expression of two dorsally expressed putative signaling molecules, fringe (fng) and Serrate (Ser), are regulated by the apterous selector gene. Here, we demonstrate that fng and Ser have distinct roles in a novel cell recognition and signal induction process. fng serves as a boundary-determining molecule such that Ser is induced wherever cells expressing fng and cells not expressing fng are juxtaposed. Ser in turn triggers the expression of genes involved in wing growth and patterning on both sides of the DV boundary.     

Memory for places: a navigational model in support of Marr's theory of hippocampal function

In this report we describe a model that applies Marr's theory of hippocampal function to the problem of map-based navigation. Like many others we attribute a spatial memory function to the hippocampus, but we suggest that the additional functional components required for map-based navigation are located elsewhere in the brain. One of the key functional components in this model is an egocentric map of space, located in the neocortex, that is continuously updated using ideothetic (self-motion) information. The hippocampus stores snapshots of this egocentric map. The modeled activity pattern of head direction cells is used to set the best egocentric map rotation to match the snapshots stored in the hippocampus, resulting in place cells with a nondirectional firing pattern. We describe an evaluation of this model using a mobile robot and demonstrate that with this model the robot can recognize an environment and find a hidden goal. This model is discussed in the context of prior experiments that were designed to discover the map-based spatial processing of animals. We also predict the results of further experiments.