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PubMed2006

International immersion programs in baccalaureate nursing education: professor and student perspectives.

This article presents the dual perspectives of professor and student in relation to the explicit need for nurses to become acutely conscious of cultural competence through self-awareness and how this influences nursing care. Mary Anne Levine, Professor of Nursing, discusses the development, planning, implementation, and evolution of the International Immersion Program (IIP) at Humboldt State University. The student experience, integration, and evaluation of IIP and its impact on one's professional and personal life are described by Elizabeth Perpetua, currently a practicing RN, who participated in the program in Nakhodka, Russia.

Attitude of Health Personnel↗
PubMed1992

[Dual photon absorptiometry in algodystrophy].

Biphotonic absorptiometry has begun to demonstrate its usefulness in the field of osteoporosis. In algodystrophy, the radiology and the degree of isotopic fixation suggest a bone disorder, although both techniques are unable to objectively quantify it. Biphotonic absorption is an scanning technique which allows the quantification of bone demineralization in the segment affected by algodystrophy and its evolutive follow-up.

Absorptiometry, Photon↗
PubMed2006

Directed evolution of Bacillus subtilis lipase A by use of enantiomeric phosphonate inhibitors: crystal structures and phage display selection.

Phage display can be used as a protein-engineering tool for the selection of proteins with desirable binding properties from a library of mutants. Here we describe the application of this method for the directed evolution of Bacillus subtilis lipase A, an enzyme that has important properties for the preparation of the pharmaceutically relevant chiral compound 1,2-O-isopropylidene-sn-glycerol (IPG). PCR mutagenesis with spiked oligonucleotides was employed for saturation mutagenesis of a stretch of amino acids near the active site. After expression of these mutants on bacteriophages, dual selection with (S)-(+)- and (R)-(-)-IPG stereoisomers covalently coupled to enantiomeric phosphonate suicide inhibitors (SIRAN Sc and Rc inhibitors, respectively) was used for the isolation of variants with inverted enantioselectivity. The mutants were further characterised by determination of their Michaelis-Menten parameters. The 3D structures of the Sc and Rc inhibitor-lipase complexes were determined and provided structural insight into the mechanism of enantioselectivity of the enzyme. In conclusion, we have used phage display as a fast and reproducible method for the selection of Bacillus lipase A mutant enzymes with inverted enantioselectivity.

Bacillus subtilis↗
PubMed2000

Evolution of the human immunodeficiency virus type 1 envelope during infection reveals molecular corollaries of specificity for coreceptor utilization and AIDS pathogenesis.

The evolution of human immunodeficiency virus type 1 infection is associated with a shift in the target cell population, driven by variability in coreceptor utilization resulting from diversity in env. To elucidate the potential consequences of these changes for Env-mediated fusion over the course of AIDS, we examined the biological properties of serial viral isolates and determined coreceptor utilization by the products of env cloned from two individuals, followed from the detection of seroconversion throughout the course of their infection. One had a typical course, and the other had an accelerated progression. Early isolates were non-syncytium inducing, and the corresponding Env exclusively utilized CCR5, whereas Env from late phases of infection showed restricted utilization of CXCR4 in both patients. Env from subject SC24, who had a standard progression, demonstrated multitropism, manifested by utilization of CCR3, CXCR4, and CCR5 in the intervening period. In contrast, Env from patient SC51, who experienced early conversion to the syncytium-inducing phenotype, developed dualtropic coreceptor utilization of CCR5 and CXCR4. Genetic analysis of env from each isolate revealed that those with an X4 phenotype formed a distinct subcluster within each subject. Analysis of chimeras constructed from R5 and multispecific env from patient SC24 demonstrated that while the V3 domain played a dominant role in determining coreceptor utilization, sequences in the V4-V5 region also contributed to the latter phenotype. Immunoprecipitation experiments confirmed that the hybrid Env proteins were expressed at similar levels. These experiments demonstrate that progression from the R5 to X4 phenotype may occur through a multi- or dual-tropic intermediate and that multiple domains contribute to this process.

Acquired Immunodeficiency Syndrome↗
PubMed1999

The evolution of codon preferences in Drosophila: a maximum-likelihood approach to parameter estimation and hypothesis testing.

Synonymous codon usage in related species may differ as a result of variation in mutation biases, differences in the overall strength and efficiency of selection, and shifts in codon preference-the selective hierarchy of codons within and between amino acids. We have developed a maximum-likelihood method to employ explicit population genetic models to analyze the evolution of parameters determining codon usage. The method is applied to twofold degenerate amino acids in 50 orthologous genes from D. melanogaster and D. virilis. We find that D. virilis has significantly reduced selection on codon usage for all amino acids, but the data are incompatible with a simple model in which there is a single difference in the long-term Ne, or overall strength of selection, between the two species, indicating shifts in codon preference. The strength of selection acting on codon usage in D. melanogaster is estimated to be |Nes| approximately 0.4 for most CT-ending twofold degenerate amino acids, but 1.7 times greater for cysteine and 1.4 times greater for AG-ending codons. In D. virilis, the strength of selection acting on codon usage for most amino acids is only half that acting in D. melanogaster but is considerably greater than half for cysteine, perhaps indicating the dual selection pressures of translational efficiency and accuracy. Selection coefficients in orthologues are highly correlated (rho = 0.46), but a number of genes deviate significantly from this relationship.

Amino Acids↗
PubMed2002

Dinosaur locomotion from a new trackway.

Ardley Quarry in Oxfordshire, UK, contains one of the most extensive dinosaur-trackway sites in the world, with individual trackways extending for up to 180 metres. We have discovered a unique dual-gauge trackway from a bipedal theropod dinosaur from the Middle Jurassic in this locality, which indicates that these large theropods were able to run and that they used different hindlimb postures for walking and running. Our findings have implications for the biomechanics and evolution of theropod locomotion.

Biological Evolution↗
PubMed2006

Threshold electron-impact ionization mechanism for hydrogen atoms.

The near-threshold evolution of electron-impact ionization of hydrogen is revealed with measurements of the angular and energy correlations of the outgoing electrons down to 0.05 eV. The single-, double-, and triple-differential cross sections in the perpendicular plane are measured simultaneously using a dual wedge-and-strip detector on a single-toroidal energy analyzer, avoiding many experimental problems. The experimental and calculated data are in excellent agreement, within the experimental precision of +/-10%, and provide further evidence that the accurate solution of the Schrödinger equation provides a complete description of the reaction dynamics of near-threshold ionization.

Journal Article↗
PubMed1994

Energy cost of translational proofreading in vivo. The aminoacylation of transfer RNA in Escherichia coli.

In many cases, the intrinsic binding energies of amino acids to aminoacyl-tRNA synthetases are inadequate to give the required accuracy of translation. This has necessitated the evolution of a second determinant of specificity, proofreading, or editing mechanisms that involve the expenditure of energy to remove errors. Studies of an error-editing function of bacterial methionyl-tRNA synthetase have led to the discovery of a distinct chemical mechanism of editing and to molecular dissection of the dual synthetic-editing function of the active site of the synthetase. Studies have also established the importance of proofreading in living cells and allowed direct measurements of energy costs associated with editing in vivo. An unexpected outcome of these studies was a discovery of functional and structural similarities between methionyl-tRNA synthetase and S-adenosylmethionine synthetase, suggesting an evolutionary relationship between the two proteins. The mechanism of editing involves a nucleophilic attack of a sulfur atom on the side chain of homocysteine in homocysteinyl adenylate on its carbonyl carbon, yielding homocysteine thiolactone. The model of the active site of methionyl-tRNA synthetase derived from structure-function studies explains how the active site partitions amino acids between synthetic and editing pathways. Hydrophobic and hydrogen bonding interactions of active site residues Trp305 and Tyr15 with the side chain of methionine prevent the cognate amino acid from entering the editing pathway. These interactions are missing in the case of the smaller side chain of the noncognate homocysteine, which therefore enters the editing pathway. Homocysteine thiolactone is formed as a result of editing of homocysteine by methionyl-tRNA synthetase in bacteria, yeast, and some cultured mammalian cells. In mammalian cells, enhanced synthesis of homocysteine thiolactone, is, thus far, associated with oncogenic transformation. In E. coli, most of the energy cost of proofreading by methionyl-tRNA synthetase is due to editing of the incorrect product, homocysteinyl adenylate.

Adenosine Triphosphate↗
PubMed2005

Diffusion-tensor magnetic resonance imaging detects normal-appearing white matter damage unrelated to short-term disease activity in patients at the earliest clinical stage of multiple sclerosis.

BACKGROUND: Diffusion-tensor (DT) magnetic resonance imaging (MRI) has the potential to elucidate some characteristics of tissue microstructure inaccessible to other MRI techniques. OBJECTIVE: To investigate whether normal-appearing brain tissue abnormalities occur in patients with multiple sclerosis at the earliest clinical stage and whether their severity is predictive of a short-term disease evolution by using DT MRI. DESIGN: Forty-five patients and 22 healthy control subjects were studied. All patients had had a clinically isolated syndrome within the 3 months preceding study enrollment and paraclinical evidence of disease dissemination in space. During a single session, dual-echo, pulsed-gradient spin-echo echo-planar, and postgadolinium T1-weighted images of the brain were obtained from each subject. In patients, dual-echo and enhanced images were obtained after 3 and 12 months, to detect MRI signs of disease dissemination in time. An on-study neurological examination was also conducted to ascertain the occurrence of clinical relapses. Mean diffusivity and fractional anisotropy maps were derived from DT images. Normal-appearing white matter (NAWM) and normal-appearing gray matter mean diffusivity and fractional anisotropy histograms were produced and analyzed. RESULTS: During the study period, 29 patients showed MRI evidence of disease dissemination in time. When compared with healthy controls, patients showed higher average NAWM mean diffusivity (P = .01), lower average NAWM mean diffusivity peak height (P < .001), and fractional anisotropy (P < .001). The DT MRI characteristics of patients did not differ between those with and those without disease dissemination in time at follow-up. CONCLUSIONS: In patients with multiple sclerosis at the earliest clinical stage, the severity of NAWM damage does not predict new lesion formation in the short term, suggesting that the "diffuse" component of tissue damage is, at least partially, independent of the "discrete," predominantly inflammatory aspects of the disease since its clinical onset.

Adult↗
PubMed2002

Lamins: building blocks or regulators of gene expression?

Intermediate filament (IF) proteins are the building blocks of cytoskeletal filaments, the main function of which is to maintain cell shape and integrity. The lamins are thought to be the evolutionary progenitors of IF proteins and they have profound influences on both nuclear structure and function. These influences require the lamins to have dynamic properties and dual identities--as building blocks and transcriptional regulators. Which one of these identities underlies a myriad of genetic diseases is a topic of intense debate.

Animals↗
PubMed2006

Analysis of the Petunia TM6 MADS box gene reveals functional divergence within the DEF/AP3 lineage.

Antirrhinum majus DEFICIENS (DEF) and Arabidopsis thaliana APETALA3 (AP3) MADS box proteins are required to specify petal and stamen identity. Sampling of DEF/AP3 homologs revealed two types of DEF/AP3 proteins, euAP3 and TOMATO MADS BOX GENE6 (TM6), within core eudicots, and we show functional divergence in Petunia hybrida euAP3 and TM6 proteins. Petunia DEF (also known as GREEN PETALS [GP]) is expressed mainly in whorls 2 and 3, and its expression pattern remains unchanged in a blind (bl) mutant background, in which the cadastral C-repression function in the perianth is impaired. Petunia TM6 functions as a B-class organ identity protein only in the determination of stamen identity. Atypically, Petunia TM6 is regulated like a C-class rather than a B-class gene, is expressed mainly in whorls 3 and 4, and is repressed by BL in the perianth, thereby preventing involvement in petal development. A promoter comparison between DEF and TM6 indicates an important change in regulatory elements during or after the duplication that resulted in euAP3- and TM6-type genes. Surprisingly, although TM6 normally is not involved in petal development, 35S-driven TM6 expression can restore petal development in a def (gp) mutant background. Finally, we isolated both euAP3 and TM6 genes from seven solanaceous species, suggesting that a dual euAP3/TM6 B-function system might be the rule in the Solanaceae.

Base Sequence↗
PubMed2001

Modern human ancestry at the peripheries: a test of the replacement theory.

The replacement theory of modern human origins stipulates that populations outside of Africa were replaced by a new African species of modern humans. Here we test the replacement theory in two peripheral areas far from Africa by examining the ancestry of early modern Australians and Central Europeans. Analysis of pairwise differences was used to determine if dual ancestry in local archaic populations and earlier modern populations from the Levant and/or Africa could be rejected. The data imply that both have a dual ancestry. The diversity of recent humans cannot result exclusively from a single Late Pleistocene dispersal.

Africa↗
PubMed1997

Thoracic and abdominal SPECT-CT image fusion without external markers in endocrine carcinomas. The Group of Thyroid Tumoral Pathology of Champagne-Ardenne.

UNLABELLED: Superimposition of SPECT and computed tomography (CT) slices from the thoracoabdominal region was achieved without the use of external markers for 14 studies in 13 patients with endocrine carcinoma. Technical feasibility and clinical validation of this retrospective fusion method were assessed. METHODS: Patients had a history of thyroid cancer or of carcinoid tumor. To detect tumor sites, CT scan and dual-isotope tomoscintigraphy were performed, with 99mTc-hydroxymethylene diphosphonate for bone scintigraphy and with 111In-pentetreotide, 131I or 131I-metaiodobenzylguanidine for tumor scintigraphy (TS). A superimposition method previously developed for the pelvic region was adapted to the nonrigid thoraco-abdominal region. CT-bone scintigraphy and CT-TS superimposed images were obtained. Clinical validation of the information obtained from the superimposed images was obtained from surgery or follow-up imaging studies performed after clinical evolution of the disease process. RESULTS: Reliable and reproducible registration was achieved in all patients. CT-TS superimposed images produced accurate localization of abnormal TS foci. Accuracy was limited primarily by variable relative displacements of the thoracoabdominal organs. For 10 sites in 8 patients, localization and/or characterization obtained from CT-TS images was confirmed by a reference technique. Superimposition enabled the localization of tumor sites that otherwise could not have been suspected from CT alone and allowed the characterization of CT suspicious masses and the confirmation of CT positive sites. Nonspecific tumor TS uptake sites were also localized. CONCLUSION: With standard CT and dual-isotope SPECT acquisitions, SPECT-CT fusion is feasible in the thoracoabdominal region without the use of external markers. Fused images were validated in 8 patients for 10 sites. The use of this technique could probably improve the management and care of patients with endocrine carcinoma.

3-Iodobenzylguanidine↗
PubMed2006

Long-term evolution of body composition after renal transplantation: 5-year survey.

BACKGROUND: Thanks to advancements in immunosuppression, patients are living longer with kidney transplants, and nonimmunologic factors (particularly nutritional) have become a major source of morbidity and mortality after successful kidney transplantation (KTx). In this current study, we have prospectively assessed, in a cohort of kidney transplant recipients (KTR), the course of some nonimmunologic factors liable to hinder the long-term outcome of KTR. METHODS: Forty-four consecutive KTR with stable functioning grafts received dietary recommendations and were on the lowest effective dose of steroids. Biochemical nutritional markers, C-reactive protein, lipid profile, and body composition determined by dual-energy X-ray absorptiometry were studied over the first year, 2 years, and 5 years after KTx. RESULTS: No patients died during the follow-up. All patients but 2 were considered normotensive. Clinical diabetes developed in 3 patients. Visceral proteins stabilized at a normal range after the first year. Most of the patients normalized their inflammatory status. A significant improvement in lipid profile was observed. Female patients had a significant increase of weight (13.5%), mainly because of an increase in fat mass: 3.4 kg (19.4%) at 1 year and 5.6 kg (29.7%) at 2 years. In male patients, body composition remained stable and close to baseline values. The evolution of bone mass varied according to gender, total corticoid doses, and calcineurin inhibitors. Patients on low doses of steroids normalized their Z-score over the 5-year period. The increase in bone mass (paired t-test, P = .006) was only significant in patients treated with tacrolimus (analysis of variance for repeated measures, P < .001). CONCLUSIONS: Simple measures and dietary intervention to prevent or correct nonimmunologic disorders should permit improvement of long-term morbidity and mortality of KTR without compromising the functional outcome of their transplant.

Absorptiometry, Photon↗
PubMed1999

Biochemical and structural studies with neutralizing antibodies raised against foot-and-mouth disease virus.

The function of a loop exposed on the aphthovirus capsid (the G-H loop of protein VP1) has been explored by combining genetic and structural studies with viral mutants. The loop displays a dual function of receptor recognition and interaction with neutralizing antibodies. Remarkably, some amino acid residues play a critical role in both such disparate functions. Therefore residues subjected to antibody pressure for variation may nevertheless maintain a role in receptor recognition for which invariance is a requirement. Evolution of FMDV in cell culture may relax the requirements at this site and allow further increase of antigenic diversification. Essential residues at one stage of virus evolution may become dispensable at another not very distant point in the evolutionary landscape. Implications for FMDV evolution and vaccine design are discussed.

Animals↗
PubMed2000

Simultaneous detection of BCL-2 protein, trisomy 12, retinoblastoma and P53 monoallelic gene deletions in B-cell chronic lymphocytic leukemia by fluorescence in situ hybridization (FISH): relation to disease status.

Various genetic abnormalities are often found in B-CLL, but their relative importance in the pathogenesis and evolution of the disease has not been adequately clarified. We studied the expression of bcl-2 protein and the possible simultaneous occurrence of bcl-2 overexpression, trisomy 12 and the Rb1 and p53 gene deletions in 38 patients with B-CLL by combining immunophenotyping and dual color interphase FISH. We also looked for correlation between the genetic abnormalities and clinical parameters such as stage, disease duration from diagnosis to the time of study and overall survival. High expression of the bcl-2 protein was found in 76.3% of the patients (29/38). Trisomy 12 was found in 37% of cases (14/38) and Rb1 monoallelic gene deletion in 42% (16/38). The percentage of cells with hemizygous Rb1 deletion ranged from 13 to 18%. Monoallelic deletion of p53 was found in 29% of cases (11/38). The number of cells with only one signal ranged from 28 to 98%. Patients in stage A had on average, less than one abnormality, while patients in stage C had 2.6 abnormalities. Patients appeared to accumulate genetic abnormalities with time. Bcl-2 overexpression was found early in the course of the disease. Trisomy 12 appeared later, at about the same time as Rb1 deletion, but was not associated with adverse prognosis. Monoallelic deletion of p53 gene appeared rather late in the course of the disease and was associated with advanced stage. Despite the fact that more deaths occurred in the group of patients with three or four abnormalities and the presence of p53 gene deletion, differences in survival were not statistically significant, probably due to the limited number of patients in each group. A larger group of patients studied in a prospective manner will better clarify these issues in the future.

Aged↗
PubMed2006

Evolution of cytokine responses: IL-1beta directly affects intracellular Ca2+ concentration of teleost fish leukocytes through a receptor-mediated mechanism.

In this work we studied the biological activities of recombinant IL-1beta from the teleosts sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) by investigating the effects induced on intracellular Ca2+ concentrations ([Ca2+]i) of spleen leucocytes. Splenocytes were loaded with the Ca2+-permeant Fura-2AM, and then stimulated with rIL-1beta. The emitted fluorescence was read for 5 min at 1 min intervals on a dual excitation fluorescence fluorimeter. Results showed that rIL-1beta induced in both species a rise in [Ca2+]i, and a subsequent decrease until 5 min after stimulation. The stimulating effect was dose-dependent in both species reaching a plateau at 200 ng/ml of rIL-1beta, was abolished by heat-treatment of rIL-1beta, and affected in a dose-dependent fashion by treatment of leucocytes with trypsin. These features suggested a functional IL-1 receptor was involved in the binding. The observed rise in [Ca2+]i was not detected in human PBMC and was species-specific, since rIL-1beta from sea bass, trout, and human were unable to interfere each other in the assay. Moreover, incubation of splenocytes with rIL-1beta induced a rapid tyrosine phosphorylation of a 24 kDa polypeptide in both species. This work represents the first evidence of a direct effect on [Ca2+]i induced by IL-1beta and suggests that in the evolution of IL-1 activities, teleost fishes display a peculiar IL-1-associated behaviour that is lacking in mammals.

Animals↗
PubMed2001

Remarkable conservation of translation initiation factors: IF1/eIF1A and IF2/eIF5B are universally distributed phylogenetic markers.

Initiation of protein biosynthesis is an essential process occurring in cells throughout the three phylogenetic domains, Bacteria, Archaea, and Eucarya. IF1/eIF1A and IF2/eIF5B, two conserved translation initiation factors are involved in this important step of protein biosynthesis. The essentiality, universal distribution, conservation, and interspecies functional homology of both factors are a unique combination of properties ideal for molecular phylogenetic studies as demonstrated by the extensively compared SSU rRNAs. Here, we assess the use of IF1/eIF1A and IF2/eIF5B in universal and partial phylogenetic studies by comparison of sequence information from species within all three phylogenetic domains and among closely related strains of Haemophilus parainfluenzae. We conclude that the amino acid sequence of IF1/eIF1A-IF2/eIF5B is a universal phylogenetic marker and that the nucleotide sequence of the IF2/eIF5B G-domain is more credible than SSU rRNA for the construction of partial phylogenies among closely related species and strains. Because of these two application levels, IF1/eIF1A-IF2/eIF5B is a phylogenetic "dual level" marker.

Amino Acid Sequence↗