Susceptibility of members of the family Legionellaceae to thermal stress: implications for heat eradication methods in water distribution systems.

To ascertain the feasibility of heat inactivation as an eradication method applicable to all members of the family Legionellaceae, we tested the heat resistance of 75 isolates which represented 19 members of this family of organisms. The ranges of thermal death times at 60, 70, and 80 degrees C were 1.3 to 10.6, 0.7 to 2.6, and 0.3 to 0.7 min, respectively. These data suggest that the method of heat eradication will be effective against all members of the family Legionellaceae.     

Total family unit Helicobacter pylori eradication and pediatric re-infection rates

BACKGROUND: Re-infection with Helicobacter pylori is more common in children than adults, and it is generally accepted that the family unit plays a significant role in primary childhood infection. We investigated whether the family unit plays a significant role in pediatric re-infection and if eradication of H. pylori from the entire family reduces the risk of childhood re-infection. METHODS: Fifty families, each with an H. pylori-infected pediatric index case (mean age 9.48 years), were recruited. A 13carbon urea breath test was performed on all family members in the same house as the index case. Each family unit was randomized into a 'family unit treatment' group (all infected family members treated) or an 'index case treatment' group (index case only treated). RESULTS: At long-term follow-up (mean 62.2 months), there were three re-infected children in the 'index case treatment' group compared with one in the 'family unit treatment' group. The re-infection rate was 2.4% per patient per year in the 'index case treatment' group and 0.7% per patient per year in the 'family unit treatment' group (p = .31). CONCLUSIONS: This study is the first to evaluate the effect of total family unit H. pylori eradication on pediatric re-infection rates and reports the longest period of re-infection follow-up in children. In childhood, re-infection with H. pylori is not significantly reduced by family unit H. pylori eradication.     

Occurrence and Diversity of <Emphasis Type="Italic">Legionellaceae</Emphasis> in Polar Lakes of the Antarctic Peninsula

Legionellaceae is a family of Gram-negative, mesophilic, and facultative intracellular parasitic bacteria that inhabits freshwater environments. In this article, the Legionella population of water samples from the North and South Lake, located close to the Brazilian Scientific Station on King George Island, Keller Peninsula, Antarctica has been characterized. Culture onto selective medium and a independent-culture method were applied to the samples. In our attempt to isolate Legionella species from Antarctic lakes, we were able to obtain one L. pneumophila colony by an amoebic coculture procedure followed by plate culture onto a selective medium. In addition, results obtained from phylogenetic inference showed the presence of noncharacterized specimens of Legionella spp. These findings indicated the presence of legionellae in Antarctica and suggest that these bacteria can adapt to extreme conditions and open new possibilities for understanding the survival strategies of mesophilic Legionellaceae living in Antarctic environments. Furthermore, the isolation of these symbiotic bacteria in Antarctic lakes will allow future studies on cold-resistant mechanisms of legionellae in polar environments.     

Coordinate and non-coordinate expression of the stress 70 family and other molecular chaperones at high and low temperature in spinach and tomato

Stress 70 molecular chaperones are found in all the major subcellular compartments of plant cells, and they are encoded by a multigene family. Twelve members of this family have been identified in spinach. The expression of the stress 70 molecular chaperones in response to heat shock is well-known and it appears that low temperature exposure can also stimulate their expression. However, it has been difficult to determine which member(s) of the family are specifically responsive to low temperature. This study was initiated to determine the levels of expression of the stress 70 family members and other selected chaperones in response to high and low temperature exposure. During heat shock of spinach, of the 10 stress 70 family members that were examined, all 10 showed increased RNA levels after one hour, and all showed down-regulation at longer durations of high temperature exposure. However, the response to low temperature was quite variable and complex. Some members were induced, some were transiently up-regulated, while others showed sustained up-regulation at a low non-freezing temperature. In comparison, the entirety of the molecular chaperone expression response of cold-sensitive tomato at the same low non-freezing temperature was even more dramatic with 11 of 15 molecular chaperones tested exhibiting elevated expression. The increased chaperone expression is consistent with the hypothesis that the biogenesis or stability of some proteins is compromised at low non-freezing temperatures. In contrast, mild freezing sufficient to cause injury of spinach did not materially activate chaperone expression.     

Translation of some maize small heat shock proteins is initiated from internal in-frame AUGs.

Etiolated maize radicles (inbred Oh43) subjected to a brief heat shock synthesize a family of small heat shock proteins (approximately 18 kD) that is composed of at least 12 members. We previously described the cDNA-derived sequence of three maize shsp mRNAs (cMHSP18-1, cMHSP18-3, and cMHSP18-9). In this report, we demonstrate that the mRNA transcribed in vitro from one of these cDNAs (cMHSP18-9) is responsible for the synthesis of three members of the shsp family, and we suggest that cMHSP18-3 may be responsible for the synthesis of three additional members and cMHSP18-1 for the synthesis of two other members of this family. The fact that these genes do not contain introns, coupled with the observations reported herein, suggest that maize may have established another method of using a single gene to produce a number of different proteins.     

Glycine-containing selective medium for isolation of Legionellaceae from environmental specimens.

Glycine, at a final concentration of 0.3%, has been shown to be an excellent selective agent for the isolation of Legionellaceae. Stock cultures of Legionella pneumophila were not inhibited on buffered charcoal-yeast extract agar containing the amino acid. Among the other Legionellaceae tested, only one of two strains of L. dumoffii and two of six strains of L. micdadei were appreciably inhibited. This medium permitted the isolation of L. pneumophila from environmental specimens with marked inhibition of many non-Legionellaceae bacteria. The selectivity of the medium was subsequently improved by the incorporation of vancomycin (5 microgram/ml) and polymyxin B (100 U/ml). This selective medium, glycine-vancomycin-polymyxin B agar, should facilitate the recovery of Legionellaceae from environmental sources.     

Use of surface-enhanced laser desorption ionization-time-of-flight to identify heat shock protein 70 isoforms in closely related species of the virilis group of Drosophila

The 70-kDa heat shock protein (Hsp) family in all Drosophila species includes 2 environmentally inducible family members, Hsp70 and Hsp68. Two-dimensional gel electrophoresis revealed an unusual pattern of heat shock-inducible proteins in the species of the virilis group. Trypsin fingerprinting and microsequencing of tryptic peptides using ProteinChip Array technology identified the major isoelectric variants of Hsp70 family, including Hsp68 isoforms that differ in both molecular mass and isoelectric point from those in Drosophila melanogaster. The peculiar electrophoretic mobility is consistent with the deduced amino acid sequence of corresponding hsp genes from the species of the virilis group.     

Heat inactivation of staphylococcus epidermidis at various water activities.

Members of the family Micrococcaceae play an important role in food spoilage and even in food poisoning. In contrast to members of the family Enterobacteriaceae, these bacteria can grow in media with low water activities. Therefore, the heat resistance of Staphylococcus epidermidis, a rather resistant member of the family Micrococcaceae, was studied at water activities between 0.87 and 1.00. The heat inactivation curves were clearly biphasic at all temperatures and water activities tested. Especially at low water activities, the D-values of the tail phase were extremely high (at 0.87 water activity, a D-value at 70 degrees C of 500 s was recorded).     

Synergistic effects of heat and antibiotics on Pseudomonas aeruginosa biofilms

Upon formation of a biofilm, bacteria undergo several changes that prevent eradication with antimicrobials alone. Due to this resistance, the standard of care for infected medical implants is explantation of the infected implant and surrounding tissue, followed by eventual reimplantation of a replacement device. Recent studies have demonstrated the efficacy of heat shock for biofilm eradication. To minimize the heat required for in situ biofilm eradication, this study investigated the hypothesis that antibiotics, while ineffective by themselves, may substantially increase heat shock efficacy. The combined effect of heat and antibiotics on Pseudomonas aeruginosa biofilms was quantified via heat shock in combination with ciprofloxacin, tobramycin, or erythromycin at multiple concentrations. Combined treatments had synergistic effects for all antibiotics for heat shock conditions of 60°C for 5 min to 70°C for 1 min, indicating an alternative to surgical explantation.     

被子植物小热激蛋白家族的比较基因组学分析

小热激蛋白(sHSP)是一类重要的响应外界环境变化以及调控植物生长发育的蛋白家族。基于在睡莲(Nymphaea colorata)、水稻(Oryza sativa)、拟南芥(Arabidopsis thaliana)和葡萄(Vitis vinifera)中分别鉴定到的33个NcsHSPs、24个OssHSPs、17个A...     

A family of Turandot-related genes in the humoral stress response of Drosophila.

The Drosophila Turandot A (TotA) gene was recently shown to encode a stress-induced humoral factor which gives increased resistance to the lethal effects of high temperature. Here we show that TotA belongs to a family of eight Tot genes distributed at three different sites in the Drosophila genome. All Tot genes are induced under stressful conditions such as bacterial infection, heat shock, paraquat feeding or exposure to ultraviolet light, suggesting that all members of this family play a role in Drosophila stress tolerance. The induction of the Tot genes differs in important respects from the heat shock response, such as the strong but delayed response to bacterial infection seen for several of the genes.     

Systematic review and meta-analysis: Helicobacter pylori eradication therapy after simple closure of perforated duodenal ulcer

Background: The most common complications of peptic ulcer are bleeding and perforation. In many regions, definitive acid reduction surgery has given way to simple closure and Helicobacter pylori eradication. Aim: To perform a systematic review and meta‐analysis to ask whether this change in practice is in fact justified. Materials and Methods: A search on the Cochrane Controlled Trials Register, Medline, and Embase was made for controlled trials of duodenal ulcer perforation patients using simple closure method plus postoperative H. pylori eradication therapy versus simple closure plus antisecretory non‐eradication therapy. The long‐term results for prevention of ulcer recurrence were compared. Results: The pooled incidence of 1‐year ulcer recurrence in H. pylori eradication group was 5.2% [95% confidence interval (CI) of 0.7 and 9.7], which is significantly lower than that of the control group (35.2%) with 95% CI of 0.25 and 0.45. The pooled relative risk was 0.15 with 95% CI of 0.06 and 0.37. Conclusions: Helicobacter pylori eradication after simple closure of duodenal ulcer perforation gives better result than the operation plus antisecretory non‐eradication therapy for prevention of ulcer recurrence. All duodenal ulcer perforation patients should be tested for H. pylori infection, and eradication therapy is required in all infected patients.     

RNA: a method to specifically inhibit PCR amplification of known members of a multigene family by degenerate primers

The polymerase chain reaction (PCR) is a versatile method to amplify specific DNA with oligonucleotide primers. By designing degenerate PCR primers based on amino acid sequences that are highly conserved among all known gene family members, new members of a multigene family can be identified. The inherent weakness of this approach is that the degenerate primers will amplify previously identified, in addition to new, family members. To specifically address this problem, we synthesized a specific RNA for each known family member so that it hybridized to one strand of the template, adjacent to the 3′-end of the primer, allowing the degenerate primer to bind yet preventing extension by DNA polymerase. To test our strategy, we used known members of the soluble, nitric oxide-sensitive guanylyl cyclase family as our templates and degenerate primers that discriminate this family from other guanylyl cyclases. We demonstrate that amplification of known members of this family is effectively and specifically inhibited by the corresponding RNAs, alone or in combination. This robust method can be adapted to any application where multiple PCR products are amplified, as long as the sequence of the desired and the undesired PCR product(s) is sufficiently distinct between the primers.     

Genomic analysis of the Hsp70 superfamily in Arabidopsis thaliana

The Arabidopsis genome contains at least 18 genes encoding members of the 70-kilodalton heat shock protein (Hsp70) family, 14 in the DnaK subfamily and 4 in the Hsp110/SSE subfamily. While the Hsp70s are highly conserved, a phylogenetic analysis including all members of this family in Arabidopsis and in yeast indicates the homology of Hsp70s in the subgroups, such as those predicted to localize in the same subcellular compartment and those similar to the mammalian Hsp110 and Grp170. Gene structure and genome organization suggest duplication in the origin of some genes. The Arabidopsis hsp70s exhibit distinct expression profiles; representative genes of the subgroups are expressed at relatively high levels during specific developmental stages and under thermal stress.     

Expression of members of the Saccharomyces cerevisiae hsp70 multigene family

The hsp70 multigene family of Saccharomyces cerevisiae is a complex multigene family, composed of members exhibiting complex patterns of regulation. Expression of some members is induced after a heat shock, whereas expression of others is repressed. Some members of the family are expressed during exponential growth. One gene, SSA3, shows an unusual pattern of expression during approach to stationary phase. While most RNAs decrease in abundance, SSA3 RNA levels dramatically increase. The constitutive expression of SSA3 in cells lacking adenylate cyclase activity suggests that cAMP modulates SSA3 expression.