Patterns of spore locations in pairs of Bacillus cereus sporangia.

The location patterns, relative to the cross wall, of terminal-to-subterminal Bacillus cereus spores were determined in pairs of sporangia. The presence of three types of patterns suggests that spores are randomly located, but medium-dependent variability of the frequency ratios of the patterns strongly suggests that nonrandom localization cannot be discounted.     

Effects of different disinfection and sterilization methods on tensile strength of materials used for single-use devices

Driven by economic and time constraints, some medical centers and third parties are resterilizing single-use devices (SUDs) for reuse. The steam autoclave is quick, but most plastics used in SUDs cannot survive the temperature. Thus, a number of new methods of cleaning, disinfecting, and sterilizing these complex devices are being introduced on the market. The present study investigated the effects of a range of methods on the tensile strength of latex rubber, silicone elastomer, 2 different formulations of polyurethane, nylon, and high-density polyethylene (HDPE) specimens. The methods used were sodium hypochlorite bleach (Clorox), peracetic acid + hydrogen peroxide (Steris), formaldehyde gas (Chemiclave), low-temperature peracetic acid and gas plasma (Plazlyte), and low-temperature hydrogen peroxide gas plasma (Sterrad). The results showed that silicone elastomer was minimally affected, whereas the strengths of nylon, polyethylene, and latex were reduced by some of the methods. Depending on the formulation, the strength of polyurethane either increased or decreased. The data demonstrated that disinfection and sterilization can affect the tensile strength of certain materials used in medical devices.     

Duplication of 7p11.2-p13, including GRB10, in Silver-Russell syndrome

Silver-Russell syndrome (SRS) is characterized by pre- and postnatal growth failure and other dysmorphic features. The syndrome is genetically heterogeneous, but maternal uniparental disomy of chromosome 7 has been demonstrated in approximately 7% of cases. This suggests that at least one gene on chromosome 7 is imprinted and involved in the pathogenesis of SRS. We have identified a de novo duplication of 7p11.2-p13 in a proband with features characteristic of SRS. FISH confirmed the presence of a tandem duplication encompassing the genes for growth factor receptor-binding protein 10 (GRB10) and insulin-like growth factor-binding proteins 1 and 3 (IGFBP1 and -3) but not that for epidermal growth factor-receptor (EGFR). Microsatellite markers showed that the duplication was of maternal origin. These findings provide the first evidence that SRS may result from overexpression of a maternally expressed imprinted gene, rather than from absent expression of a paternally expressed gene. GRB10 lies within the duplicated region and is a strong candidate, since it is a known growth suppressor. Furthermore, the mouse homologue (Grb10/Meg1) is reported to be maternally expressed and maps to the imprinted region of proximal mouse chromosome 11 that demonstrates prenatal growth failure when it is maternally disomic. We have demonstrated that the GRB10 genomic interval replicates asynchronously in human lymphocytes, suggestive of imprinting. An additional 36 SRS probands were investigated for duplication of GRB10, but none were found. However, it remains possible that GRB10 and/or other genes within 7p11.2-p13 are responsible for some cases of SRS.     

Natural Atypical Listeria innocua Strains with Listeria monocytogenes Pathogenicity Island 1 Genes

Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests. Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level. We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests. The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay. The results show that this isolate is indeed a novel one. Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain. This species, by definition, is typically nonhemolytic. The L. innocua isolate contains all the members of the PrfA-regulated virulence gene cluster (Listeria pathogenicity island 1) of L. monocytogenes. It is avirulent in the mouse pathogenicity test. Avirulence is likely at least partly due to the absence of the L. monocytogenes-specific allele of iap, as well as the absence of inlA, inlB, inlC, and daaA. At least two of the virulence cluster genes, hly and plcA, which encode the L. monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L. innocua strain. The detection by PCR assays of specific L. innocua genes (lin0198, lin0372, lin0419, lin0558, lin1068, lin1073, lin1074, lin2454, and lin2693) and noncoding intergenic regions (lin0454-lin0455 and nadA-lin2134) in the strain is consistent with its L. innocua DNA-DNA hybridization identity. Additional distinctly different hemolytic L. innocua strains were also studied.     

Stress protein of cyanobacteria CP36: interaction with photoactive complexes and formation of supramolecular structures

Cyanobacterium Anacystis nidulans R2, Synechocystis sp. PCC 6803 (wild-type strain and mutants Delta2 and Delta3 lacking PSII and PSI, respectively), and Synechocystis sp. BO 9201 synthesize the pigment--protein complex CP36 (CPIV-4, CP43') under iron deficiency in the medium. Accumulation of CP36 is accompanied by structural reorganizations in the photosynthetic membranes. Integrating mean times of excitation relaxation (quenching) are 2.2 nsec (CP36), 1 nsec (PSI), and 420 psec (PSII in Fm state). The energy migration between CP36 and the photosystems can be described by a model of a one-layer ring of CP36 around core-complexes. The excitation from CP36 to PSI is transferred within <10 psec. The energy transfer from CP36 to PSII occurs during 170 psec. Cells with low content of CP36 probably contain only a latent fraction of unbound to phycobilisomes PSII which is the analog of PSIIbeta of higher plants. In PSI there are four binding sites for CP36 monomers per RC. PSII can bind up to 32 molecules of CP36 per RC. Cells with a large amount of CP36 contain monomer form of PSII core-complex which can bind eight tetramers of CP36 (8 binding sites). In conditions of iron deficiency only one monomer of a dimer PSII core-complex is destroyed and released chlorophyll is accumulated in CP36. Accumulation of CP36 in A. nidulans cells can be accompanied by membrane stacking which is similar to the stacking in chlorophyll b-containing organisms. The stacking can occur in the region of localization of PSII latent fraction bound to CP36. The membrane stacking shields PSII stromal surfaces from the aqueous phase for activation of electron transfer on the acceptor side of PSII.     

Properties of a thermosensitive asporogenous filamentous mutant of Bacillus megaterium

Mutant TH14 of Bacillus megaterium ATCC 19213 is thermosensitive and defective in cell-division septation and spore formation at the restrictive temperature (39 C). As a consequence, the mutant forms multinucleate aseptate filaments and is asporogenic. The mutation does not result in any qualitative compositional changes in extractable membrane proteins. At the restrictive temperature, the mutant membrane has a reduced content of a small molecular weight protein(s). A membrane protein(s) with a molecular weight of nearly 80,000 appears to be partially derepressed in the mutant grown at the restrictive temperature. In addition, numerous unidentified spherical inclusions of fairly uniform size (diameter approximately 100 nm) are present in the cytoplasm at the restrictive temperature. They are especially concentrated at only one pole of each filament. Filamentous growth of the mutant is less sensitive to penicillin than growth in the rod form. Growth in either form is equally sensitive to d-cycloserine at the concentrations used for selection of the mutant. Temperature shift-up experiments suggest that one to two rounds of deoxyribonucleic acid (DNA) replication occur before the phenotypic expression of the mutation occurs. The septations after these replication events can be either two-division septations or a single-division septation plus a subsequent sporulation septation. This conclusion, coupled with previously reported work, supports the hypothesis that the early stages of sporulation represent a modified cell division.     

Sequential Metabolic Events During Encystment of Azobacter vinelandii

Cells of Azotobacter vinelandii are specifically induced to encyst by beta-hydroxybutyrate (BHB). The process of differentiation, which occurs over a period of 36 h, was characterized by an ordered sequence of biochemical events. Upon initiation of encystment, nitrogen fixation and glucose-6-phosphate dehydrogenase activities decreased immediately to very low levels. This was followed by an increase in the specific activities of BHB dehydrogenase, isocitrate dehydrogenase, isocitrate lyase, and malate synthase first at 3 h and then again at 21 h. The peak activity of fructose 1,6-diphosphate aldolase occurred at 6 h, and the enzyme activity then decreased gradually. Fructose 1,6-diphosphatase had peak activities at 9 and 27 h. Deoxyribonucleic acid synthesis ceased just prior to the final cell division at 4 to 6 h, but ribonucleic acid synthesis continued until the 12th h. From labeling studies and the appearance of new enzyme activities, it appeared that protein synthesis continued throughout encystment.     

Hip joint replacement surgery for idiopathic osteoarthritis aggregates in families

In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA), we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with hip OA than in those with knee OA.     

Ability of laboratory methods to predict in-use efficacy of antimicrobial preservatives in an experimental cosmetic.

The abilities of nine antimicrobial systems to preserve an experimental water-based cosmetic formulation were evaluated by six microbiological challenge tests: the U.S. Pharmacopeia test; the British Pharmacopeia test; the Cosmetic, Toiletry, and Fragrance Association test; the rapid screen test; the sequential challenge test; and the post-use test. The antimicrobial systems contained various combinations and amounts of two parabens and a quaternary compound in order to provide a broad range of preservation. The results obtained were compared with the abilities of the formulations to support maintenance and growth of microorganisms in microfloras obtained from human axilla areas and finger skin during an 8-week simulated in-use test. Without statistical analysis all of the tests predicted the results obtained with well-preserved or poorly preserved formulations. The rapid screen test was the best test for predicting differences at intermediate levels of preservation. Statistically, all of the tests were equivalent predictors of preservation efficacy in the in-use test (P = 0.05). At the P = 0.10 level, only the U.S. Pharmacopeia, British Pharmacopeia, rapid screen, Cosmetic, Toiletry, and Fragrance Association tests were significantly predictive. The results of prediction by a test, based on the preservative levels used, agreed well with the in-use test results (P = 0.01). A total of 20% of the formulations that contained excessive microbial levels contained human axilla microorganisms. The levels of preservation in failed products were similar to the levels of preservation in unused controls.