Microbiological analyses and inflammatory effects of settled dusts from rice and hay

Fourteen samples of settled dust from two factories processing rice and wheat straw near Shanghai, China, were examined by dilution plating for total bacteria, gram-negative bacteria, thermophilic actinomycetes, and fungi. They were also examined for aflatoxin, endotoxin, and potential to stimulate production of human interleukin 1 beta (IL-1 beta) and to consume complement. The concentrations of total microorganisms were consistently greater than 10(7) CFU/g and ranged from 10(7) to 10(9) CFU/g. In general, the level of microbial contamination was greater in the hay dust samples than in the rice dust samples, with bacteria being the most numerous microorganisms observed followed by molds, thermophilic actinomycetes, and yeasts. The predominant fungi were species of Aspergillus, Cladosporium, Penicillium, Trichosporon, and Cryptococcus. No significant levels of aflatoxin were observed and the isolates of A. flavus examined lack significant aflatoxigenic potential. The levels of microorganisms in these samples, the types of organisms found, and the inflammatory mediators such as endotoxin suggest that workers exposed to these dusts may be at risk for respiratory illness.     

Safety profile and immunogenicity of an inactivated vaccine derived from an attenuated strain of hepatitis A.

To determine the safety and immunogenicity of an inactivated hepatitis A vaccine, 56 healthy adult volunteers were randomly assigned to receive an intramuscular injection of 6.3, 12.5 or 25 ng of inactivated hepatitis A vaccine or placebo at 0, 2 or 4, and 24 weeks. Adverse reactions occurred with similar frequency in vaccine and placebo recipients and consisted primarily of pain or tenderness at the injection site. By 4 weeks after a single 6.3, 12.5 or 25 ng injection, seven, nine and ten out of ten vaccinees, respectively, had antibody detectable by a HAV AB assay modified to increase its sensitivity tenfold. All vaccinees had antibodies detectable by this assay within 2 weeks of their second inoculation. Geometric mean antibody levels increased with higher doses of vaccine (p = 0.05). Neutralizing antibody was detected within 4 weeks of a single inoculation in all vaccinees. Neutralizing antibody was detected after the third inoculation at dilutions of greater than or equal to 1:2048 in all 12.5 and 25 ng vaccinees. All 19 vaccinees tested at 24 months still had HAV antibodies detectable by a modified HAV AB assay. This inactivated hepatitis A vaccine appears to be well tolerated and immunogenic at doses of 6.3-25 ng. The choice of dose and vaccination schedule may depend on the rapidity with which seroconversion is desired.     

Association of myopathy with large-scale mitochondrial dna duplications and deletions: Which is pathogenic?

We identified large-scale heteroplasmic mitochondrial DNA (mtDNA) rearrangements in a 50–year-old woman with an adult-onset progressive myopathy. The predominant mtDNA abnormality was a 21.2–kb duplicated molecule. In addition, a small population of the corresponding partially deleted 4.6–kb molecule was detected. Skeletal muscle histology revealed fibers that were negative for cytochrome c oxidase (COX) activity and had reduced mtDNA-encoded COX subunits. By single-fiber polymerase chain reaction analysis, COX-negative fibers contained a low number of wild-type or duplicated mtDNA molecules (ie, nondeleted). In situ hybridization demonstrated that the abnormal fibers contained increased amounts of mtDNA compared with normal fibers and that most of the genomes were deleted. We concluded that deleted mtDNA molecules were primarily responsible for the phenotype in this patient.