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PubMed1998

Beyond risk assessment: elements for pressure ulcer prevention.

Considerable emphasis has been placed on identifying individuals who are at risk for developing pressure ulcers. However, the generality of diagnostic discriminations and consequent intervention strategies may have resulted in less effective outcomes than otherwise would be possible. When such processes are carried out in a system devoid of the fundamental elements required for increased diagnostic/prescriptive precision and systematic improvement, practitioners are, at best, relegated to relying on external trial-based research to yield new "best practices." At worst, ineffective and costly practices continue without systematic evaluation and alteration. Several necessary elements of any empirically-based prevention system are addressed, and an attempt to integrate the elements into a system for field utilization is illustrated. If successful, the system will result in incremental improvements in the outcomes of prevention efforts over time.

Evidence-Based Medicine↗
PubMed1999

Plasmid-encoded tetracycline resistance in Salmonella enterica subsp. enterica serovars choleraesuis and typhimurium: identification of complete and truncated Tn1721 elements.

During routine screening of Salmonella enterica subsp., S. enterica isolates of animal origin for plasmid-encoded tetracycline resistance, two tetracycline resistance plasmids, the 50 kbp plasmid pGFT3 of Salmonella choleraesuis and the 9.5 kbp plasmid pGFT4 of Salmonella typhimurium var. Copenhagen DT002, were detected. The respective tetracycline resistance genes (tet) were identified by hybridization and PCR analysis to belong to hybridization class A. Conjugation experiments identified plasmid pGFT3 as a conjugative plasmid. Molecular analysis of the tet(A) gene area and the flanking regions identified a complete Tn1721-like transposon on plasmid pGFT3 and a truncated Tn1721-like element on plasmid pGFT4. The complete Tn1721-like element was integrated into a transposase reading frame of a truncated Tn3 transposon also located on plasmid pGFT3. The truncated Tn1721-like element of plasmid pGFT4 lacked the entire transposase part. This Tn1721-relic was integrated in an unknown reading frame which on amino acid level showed homology to the Rop protein of Escherichia coli. A model for the deletion of the transposase part was developed on the basis of the sequences present at the termini of the truncated Tn1721-like element.

Animals↗
PubMed1996

Genetic and molecular analysis of a set of unstable white mutants in Drosophila melanogaster.

Two related unstable mutants at the white locus of Drosophila melanogaster show different interactions with the zeste1 mutant: one mutated white gene becomes repressed in males, whereas the other is unaffected by z1. By use of Southern blot techniques and by constructing genomic lambda-libraries, molecular analyses of the white regions of these two strains were performed. The results showed a single difference at a site 2.5 kb (kilobases) downstream of the white transcription unit. In both strains, FB (foldback) elements were integrated at this site, but the repressed strain also harboured a 4 kb NOF (Nofretete) element. No other restriction site polymorphisms between the two strains were observed within a 120 kb region surrounding the white gene. The extent of twelve white deletions and twelve white transpositions deriving from these unstable strains was analysed by in situ hybridisation and Southern blot techniques. The results revealed that the distal breakpoint of all aberrations coincided with the insertion site of the mobile elements, but that the centromere proximal breakpoints varied. The mechanisms for the instability and the interaction with the zeste1 mutant are discussed.

Animals↗
PubMed2000

Formation of cytoplasmic turns between two closely spaced transmembrane helices during membrane protein integration into the ER membrane.

The helical hairpin, two closely spaced transmembrane helices separated by a short turn, is a recurring structural element in integral membrane proteins, and may serve as a compact unit that inserts into the membrane en bloc. Previously, we have determined the propensities of the 20 natural amino acids, when present in the middle of a long hydrophobic stretch, to induce the formation of a helical hairpin with a lumenally exposed turn during membrane protein assembly into the endoplasmic reticulum membrane. Here, we present results from a similar set of measurements, but with the turn placed on the cytoplasmic side of the membrane. We find that a significantly higher number of turn-promoting residues need to be present to induce a cytoplasmic turn compared to a lumenal turn, and that, in contrast to the lumenal turn, the positively charged residues Arg and Lys are the strongest turn-promoters in cytoplasmic turns. These results suggest that the process of turn formation between transmembrane helices is different for lumenal and cytoplasmic turns.

Amino Acid Sequence↗
PubMed2004

Removal of biological and non-biological viral surrogates by spiral-wound reverse osmosis membrane elements with intact and compromised integrity.

The removal of bacteriophage MS2 and fluorescent-dyed polystyrene microspheres with intact and purposely compromised spiral-wound RO membrane elements was investigated. MS2 rejection with intact membrane elements was >99.9995%. A model developed for data evaluation revealed that the advective passage of MS2 through imperfections of intact membrane elements was <2 x 10(-5)% of the overall product water flow produced. The advective passage of MS2 and microspheres through a pinhole induced in one of the elements was 0.05-0.1% of the overall product water flow. Prolonged testing of both intact and compromised elements resulted in increased MS2 rejection corresponding to advective MS2 passage through membrane imperfections of <3 x 10(-7)% of the overall product water flow. The permeate flow rate obtained with an element with a larger pinhole was 5-13% greater than that of the intact element, and the corresponding rejection of MS2 and microspheres was similar to that observed for sodium chloride. The use of a cracked o-ring in the connection of the permeate tube to the element vessel end-cup resulted in advective passage of MS2 through the crack of <0.0001% of the overall permeate flow.

Fluorescent Dyes↗
PubMed1996

A new type of conjugative transposon encodes resistance to sulfamethoxazole, trimethoprim, and streptomycin in Vibrio cholerae O139.

Vibrio cholerae O139 is the first non-O1 serogroup of V. cholerae to give rise to epidemic cholera. Apparently, this new serogroup arose from an El Tor O1 strain of V cholerae, but V. cholerae O139 is distinguishable from V. cholerae El Tor O1 by virtue of its novel antigenic structure and also its characteristic pattern of resistances to the antibiotics sulfamethoxazole, trimethoprim, streptomycin, and furazolidone. We found that the first three of these antibiotic resistances are carried on an approximately 62-kb self-transmissible, chromosomally integrating genetic element which we have termed the SXT element. This novel conjugative transposon-like element could be conjugally transferred from V. cholerae O139 to V cholerae O1 and Escherichia coli strains, where it integrated into the recipient chromosomes in a site-specific manner independent of recA. To study the potential virulence properties of the SXT element as well as to improve upon the live attenuated O139 vaccine strain Bengal-2, a large internal deletion in the SXT element was crossed on to the Bengal-2 chromosome. The resulting strain, Bengal-2.SXT(s), is sensitive to sulfamethoxazole and trimethoprim and colonizes the intestines of suckling mice as well as wild-type strains do, suggesting that the SXT element does not encode a colonization factor. Derivatives of Bengal-2.SXT(s) are predicted to be safe, antibiotic-sensitive, live attenuated vaccines for cholera due to the O139 serogroup.

Animals↗
PubMed2001

An active retrotransposon in Candida albicans.

Tca2 is a Ty1/copia-type retrotransposon from the pathogenic yeast Candida albicans. It was originally identified as an abundant, linear, extrachromosomal, double-stranded DNA molecule. Here we show that Tca2 is widespread in C.albicans, but that the abundance of extrachromosomal Tca2 DNA varies greatly among different strains and is strongly dependent on the growth temperature. The relative levels of Tca2 RNA vary in a similar pattern to the extrachromosomal DNA, raising the possibility that the variations in extrachromosomal DNA levels are introduced predominantly at the level of transcription. We have also analysed the retrotranspositional activity of the element by developing a transposition assay involving a cloned Tca2 element tagged with a selectable marker gene that is activated by passage through an RNA intermediate. We show that the marked Tca2 is transpositionally active as transposed copies of the marked element became integrated at a variety of new positions in the genome and an intron in the donor element was precisely removed in the newly transposed copies. This is the first report of transposition in C.albicans.

Candida albicans↗
PubMed1995

Early adolescent girls' understanding of menstruation.

Sixth grade girls (N = 224) were queried about their preparation for and expectations about menarche, their parents' roles in preparation, and their understanding of the biological basis of menstruation, characteristics of the menstrual cycle, menstrual hygiene, and menstrual-related physical and psychological changes. Although girls viewed themselves as prepared for menarche, and claimed they had discussed it with their mothers, their explanations of menstruation reflected at best incomplete knowledge, and more typically a variety of misconceptions or ignorance. In attempting to explain menstruation, they tended to focus on one particular element of the process (e.g., eggs or blood or the uterus), and were not able to integrate the elements into a comprehensive whole. Girls' knowledge of the location and function of reproductive structures was faulty, and most did not understand how they were interrelated. Girls associated a variety of negative physical and psychological changes with menstruation, indicating that although they had not yet learned the biology of menstruation, they already had learned and internalized the cultural stereotypes and myths about menstrual symptomatology. In view of reports of high levels of sexual activity, often at very young ages, and without protection, and the high risk for acquiring sexually transmitted diseases, the failure to adequately educate girls about their own anatomy and physiology has serious implications.

Child↗
PubMed2003

SOS response promotes horizontal dissemination of antibiotic resistance genes.

Mobile genetic elements have a crucial role in spreading antibiotic resistance genes among bacterial populations. Environmental and genetic factors that regulate conjugative transfer of antibiotic resistance genes in bacterial populations are largely unknown. Integrating conjugative elements (ICEs) are a diverse group of mobile elements that are transferred by means of cell-cell contact and integrate into the chromosome of the new host. SXT is a approximately 100-kilobase ICE derived from Vibrio cholerae that encodes genes that confer resistance to chloramphenicol, sulphamethoxazole, trimethoprim and streptomycin. SXT-related elements were not detected in V. cholerae before 1993 but are now present in almost all clinical V. cholerae isolates from Asia. ICEs related to SXT are also present in several other bacterial species and encode a variety of antibiotic and heavy metal resistance genes. Here we show that SetR, an SXT encoded repressor, represses the expression of activators of SXT transfer. The 'SOS response' to DNA damage alleviates this repression, increasing the expression of genes necessary for SXT transfer and hence the frequency of transfer. SOS is induced by a variety of environmental factors and antibiotics, for example ciprofloxacin, and we show that ciprofloxacin induces SXT transfer as well. Thus, we present a mechanism by which therapeutic agents can promote the spread of antibiotic resistance genes.

Bacterial Proteins↗
PubMed1997

Integration of the yeast retrovirus-like element Ty3 upstream of a human tRNA gene expressed in yeast.

The retrovirus-like element Ty3 of Saccharomyces cerevisae integrates into the yeast genomic DNA in a position specific manner. Ty3 integrates within 1-2 base pairs of the site of transcription initiation by RNA polymerase III. The human tRNA(Lys)3 gene was used as a target for transposition in a plasmid-based assay to determine whether Ty3 integration can be targeted to a human tRNA gene. Each transposition event observed was adjacent to the site of initiation of transcription of the human tRNA gene. Therefore, heterologous tRNA genes can serve as targets for Ty3 in yeast. This is a first step toward development of a system for targeted integrations in heterologous organisms.

Chromosome Mapping↗
PubMedDate not supplied

[Manifestation of integrative activity in the neuronally isolated cortex].

By the slow bioelectrical activity parameter, with vector representation of experimental data, an attempt was made to reveal elements of integrative activity in the neuronally isolated cortex at early stages after its isolation from subcortical formations. Animals with an intact cerebral cortex were used as controls. It has been found that in spite of isolation of the cerebral cortex from synaptic influences of the subcortical structures, it possesses even at early stages after isolation (10--17th day) its own mechanisms of integrative activity, providing for the organization of background and evoked activity which are gradually normalized by the 30th to 40th day, without however reaching the level of activity of the intact cerebral cortex.

Animals↗
PubMedDate not supplied

The transposable element IS4712 prevents S-layer gene (sbsA) expression in Bacillus stearothermophilus and also affects the synthesis of altered surface layer proteins.

Cell surface (S)-layer protein synthesis in Bacillus stearothermophilus PV72/p6 is blocked when cells are grown at elevated temperature. From a culture exhibiting the S-layer-negative phenotype, the S-layer deficient mutant T5 (SbsA-) was isolated. Genetic analysis of the S-layer-encoding gene (sbsA) of mutant T5 revealed an insertion element (IS4712) integrated into the upstream regulatory region of the S-layer gene, thereby blocking sbsA transcription. The insertion element consists of 1371 base pairs which are flanked by two perfect inverted terminal repeats. Sequence similarity to other transposases of the IS4 family was detected. DNA-DNA hybridizations demonstrated that multiple homologues of IS4712 were also present within the genomes of several other thermophilic bacillus isolates. Attempts to isolate SbsA+ revertants failed. Instead, cells with altered surface proteins were detected. The synthesis of the altered S-layer proteins was correlated with the presence of IS4712 along with the occurrence of deletions in the sbsA coding region. Furthermore imprecise excision of IS4712 was detected. This work demonstrated that B. stearothermophilus is able to express at least four different S-layer proteins and that blocking of sbsA transcription by the insertion element IS4712 is associated with the expression of altered surface proteins.

5' Untranslated Regions↗
PubMed2001

Hideaway, a repeated element from Ascobolus immersus, is rDNA-associated and may resemble a retrotransposon.

A lambda library of Ascobolus immersus stock 50 was screened for repeated DNA sequences by employing differential hybridization to identify transposable elements. Several lambda clones carrying repeated DNA sequences were obtained. One clone contains a repeated DNA sequence with unusual characteristics. This DNA element appears to be associated with rDNA sequences. Its methylation pattern is also reminiscent of rDNA. Sequence analysis indicates that all or at least many copies of the element have integrated in the external spacer sequence separating the rDNA repeats, possibly to avoid complete inactivation by methylation. The element has been named "Hideaway". It possesses structural characteristics of class I retrotransposons, most notably the presence of long direct repeats. The data presented here are discussed with respect to the ability of repeated DNA sequences to escape host defense mechanisms.

Ascomycota↗
PubMed1995

Integration of heterologous DNA into the genome of Paracoccus denitrificans is mediated by a family of IS1248-related elements and a second type of integrative recombination event.

All members of the IS1248 family residing in the genome of Paracoccus denitrificans have been isolated by using a set of insertion sequence entrapment vectors. The family consists of five closely related members that integrate the entrapment vectors at distinct sites. One of these, IS1248b, was sequenced and, except for a single base change, shown to be identical to the previously isolated IS1248a. Southern analysis of genomic DNA with labeled IS1248 revealed different hybridization patterns for different isolates of P. denitrificans and Thiosphaera pantotropha. No hybridization was observed with DNA from Thiobacillus versutus and more distantly related species. From a comparison of the fingerprints it was shown that one of the members of the IS1248 family found in P. denitrificans DSM413 is absent in strain NCIB8944, although they are catalogued in international strain catalogues as identical strains. Furthermore, strains Pd1222 and Pd1235, both derivatives of P. denitrificans DSM413, were shown to have different patterns of IS1248 hybridizing restriction fragments. In 14 of 18 strains, the entrapment vectors used in this study were incorporated into the genome via IS1248-mediated cointegrate formation. In the other four strains, the entrapment vectors were shown to be integrated through a different mechanism not involving IS1248.

Base Sequence↗
PubMed2005

[Rehabilitative elements for the treatment of patients with mental disorders: are they considered in the development of guidelines?].

OBJECTIVE: In the context of the current discussion of integrating rehabilitative elements into the (acute) treatment of patients with mental disorders, it is investigated what rehabilitative elements actually are and whether these elements are considered in existing guidelines. METHODS/RESULTS: An expert-based consensus, especially results of expert ratings using a 46-item questionnaire (Delphi Technique; n = 16), shows that it is possible to specify rehabilitative elements, although there are still aspects which need further clarification. Analyses of current guidelines (using published guidelines for panic disorders) demonstrate that rehabilitative elements which are rated as important by the experts are only marginally mentioned in guidelines up to now. CONCLUSIONS: A considerable need for research exists for a further specification of rehabilitative elements and for the development of evidence based recommendations in the form of guidelines.

Consensus↗
PubMed1997

Integration specificities of two lambdoid phages (21 and e14) that insert at the same attB site.

It was shown previously that phage 21 and the defective element e14 integrate at the same site within the icd gene of Escherichia coli K-12 but that 21 integrase and excisionase excise e14 in vivo very infrequently compared to excision of 21. We show here that the reverse is also true: e14 excises itself much better than it excises an adjacent 21 prophage. In vitro integrase assays with various attP substrates delimit the minimal attP site as somewhere between 366 and 418 bp, where the outer limits would include the outermost repeated dodecamers suggested as arm recognition sites by S. J. Schneider (Ph.D. dissertation, Stanford University, Stanford, Calif., 1992). We speculate that the reason 21 attP is larger than lambda attP (240 bp) is because it must include a 209-bp sequence homologous to the 3' end of the icd transcript in order to allow icd expression in lysogens. Alteration of portions of 21 attP to their e14 counterparts shows that 21 requires both the arm site and core site sequences of 21 but that replacements by e14 sequences function in some positions. Consistent with Schneider's in vivo results, and like all other known integrases from lambdoid phages, 21 requires integration host factor for activity.

Bacterial Proteins↗
PubMed2002

Rapid prototyping for injection moulded integrated microfluidic devices and diffractive element arrays.

This paper describes two fabrication procedures that makes it possible to design, fabricate and injection mold a microfluidic system with an on board coupling element or an optical array platform in less than four hours. Epoxy masters for the array and a single diffractive element were produced using conventional soft lithography techniques and a commercially available UV curable epoxy. The fabrication of the master for the integrated microfluidic device utilized the surface chemistry of polyester and its interaction with the anionic surfactant sodium dodecyl sulfate (SDS), to selectively inhibit the adhesion between the epoxy and the polyester film during the curing reaction. The transfer of a microfluidic design and the required coupling element (632 nm holographic grating) along the base of the channel was completed in a single step. The turnaround time from design to injection molded device whether a microchannel or array was 3.5 h.

Journal Article↗
PubMed2005

The multiple layers of prevention science research.

A systematic framework for prevention science clinical research is described that explicitly links the identification of prevention needs to the implementation of research results in public health programs. The framework integrates five elements: advocacy and policy, community participation, prevention research, acceptability research, and operations and program development. These five elements are often viewed as disparate agendas, but an effective prevention science research enterprise requires that they be coordinated and integrated through all research stages--from the conceptual, to the experimental, and ultimately to the applied. Examples are provided of how this integration can be achieved from our experience in reproductive health and HIV prevention.

Biomedical Research↗