Demonstration of antigenic variation among isolates of human cytomegalovirus using monoclonal antibodies and indirect ELISA.

An indirect ELISA was developed for the detection of antigenic differences between isolates of human cytomegalovirus (HCMV) using a monoclonal antibody to an early (67 kDa) antigen. Antibody binding curves were analyzed using a microcomputer program (LISACRV) based on a nonlinear logistical model. The derivation of values for the average intrinsic association constant for seven isolates of HCMV and the prototype AD169 strain revealed significant differences between them. Because of the importance of HCMV as a pathogen, especially in immunosuppressed and AIDS patients, further investigation of the biological significance of differences between isolates of HCMV is clearly warranted.

Practical evaluation of molecular subtyping and phage typing in outbreaks of infection due to Salmonella enterica serotype typhimurium.

Identification and control of food-poisoning outbreaks due to salmonellosis depend on prompt microbiological diagnosis and subtyping to identify the causative strain. In Australia, Salmonella enterica subspecies enterica serotype typhimurium (S. typhimurium) is responsible for 40-70% of cases of human salmonellosis. Phage typing is the usual method of subtyping S. typhimurium, but on its own, has limitations. We compared it with three molecular subtyping methods using 100 isolates of S. typhimurium, representing four different phage types (PT 1, 9, 126 and 135) and comprising 74 isolates from three presumed outbreaks, 25 isolates from sporadic cases of salmonellosis and S. typhimurium ATCC 10428 (phage type 126). The isolates were divided into 11 subtypes by IS200 restriction fragment length polymorphism (RFLP) typing, four each by ribotyping and pulsed-field gel electrophoresis (PFGE) and 17 distinct strains using a combination of phage and molecular typing. Isolates from two presumed outbreaks were resolved into multiple strains, possibly explaining the failure to identify a common source for either during the original investigations. IS200 RFLP analysis was the most discriminatory and reproducible typing method. Several strains were identifiable within and shared between phage types 1, 9 and 126. Phage and IS200 RFLP typing together, would provide improved definition of S. typhimurium outbreaks.

Public school teachers in the U.S. evaluate the educational impact of student space experiments launched by expendable vehicles, aboard Skylab, and aboard Space Shuttle.

Space education is a discipline that has evolved at an unprecedented rate over the past 25 years. Although program proceedings, research literature, and historical documentation have captured fragmented pieces of information about student space experiments, the field lacks a valid comprehensive study that measures the educational impact of sounding rockets, Skylab, Ariane, AMSAT, and Space Shuttle. The lack of this information is a problem for space educators worldwide which led to a national study with classroom teachers. Student flown experiments continue to offer a unique experiential approach to teach students thinking and reasoning skills that are imperative in the current international competitive environment in which they live and will work. Understanding the history as well as the current status and educational spin-offs of these experimental programs strengthens the teaching capacity of educators throughout the world to develop problem solving skills and various higher mental processes in the schools. These skills and processes enable students to use their knowledge more effectively and efficiently long after they leave the classroom. This paper focuses on student space experiments as a means of motivating students to meet this educational goal successfully.

Culture shock. Molecular methods for diagnosis of infectious diseases.

Nucleic acid detection methods, such as polymerase chain reaction (PCR), can often detect specific microbial pathogens, virulence markers and antimicrobial resistance genes more rapidly and with greater sensitivity and specificity than culture and conventional identification and susceptibility testing. Multiplex PCR can detect multiple genes in a single assay; this capability will be greatly extended by new techniques such as the DNA chip. However, limitations and pitfalls of nucleic detection methods remain.

Comparison of cell culture, mouse inoculation, and PCR for detection of Toxoplasma gondii: effects of storage conditions on sensitivity.

The sensitivity of detection of a wild-type strain of Toxoplasma gondii by cell culture, mouse inoculation, and PCR was determined following sample storage under conditions to which clinical specimens may be subjected during transport to the testing laboratory. Sample storage at -20 degrees C significantly decreased the sensitivity of mouse inoculation. The sensitivity of cell culture decreased with sample storage at 4 and -20 degrees C. The sensitivity of PCR was reduced by storage at 4 degrees C for 48 h, freezing, and heating. These findings have implications for the selection of appropriate methods for the direct detection of T. gondii organisms in suboptimally transported clinical samples.

Human arbovirus infections along the south coast of New South Wales.

The prevalence of antibodies in human sera from the south coast of New South Wales to four arboviruses, isolated from mosquitoes collected along the south coast, was determined in an attempt to estimate the importance of these viruses in human infection. Only two viruses, Barmah Forest and Gan Gan, were considered to be of any significance.