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PubMed2004

A technique for the determination of systolic pressure variation in the systemic and pulmonary arterial circulations.

INTRODUCTION: Systolic pressure variation has previously been used to detect the presence of hypovolemia in mechanically ventilated patients but remains difficult to measure. METHODS: We describe the application of a commercially available physiological data acquisition system, PowerLab (ADI Instruments Castle Hill, NSW, Australia), to acquire and graphically display simultaneous recordings of the airway pressure, as well as systemic and pulmonary arterial pressures. The technique involves the use of standard pressure transducers to record each pressure reading and has been used to obtain measurements in patients undergoing elective cardiac surgery. RESULTS: The technique permits calculation of systolic pressure variation of both the systemic and pulmonary arterial pressure waveforms. In addition it is possible to estimate plateau airway pressure and perform expiratory hold maneuvers to determine its constitutive components delta-up and delta-down. Waveforms can be exported into MS-windows Paint and saved in JPEG or bitmap format. CONCLUSIONS: The technique described will permit future analysis of the factors affecting the systolic pressure variation for the systemic and pulmonary arterial pressure waveforms in the clinical context.

Journal Article↗
PubMed2005

A new hypothesis on the strategy for acquisition of phosphorus in arbuscular mycorrhiza: up-regulation of secreted acid phosphatase gene in the host plant.

The mycorrhiza-responsive phosphatase of Tagetes patula in symbiosis with Glomus etunicatum was detected by electrophoresis, was purified by column chromatography, and was characterized as acid phosphatase that was secreted into rhizosphere. The N-terminal amino acid sequence was determined by a gas-phase sequencer, and a cDNA fragment of the phosphatase gene (TpPAP1) was amplified by degenerate primers designed based on the N-terminal amino acid sequence. The full-length cDNA was obtained by the rapid amplification of cDNA ends technique. The TpPAP1 was of host origin, and the cDNA was 1,843 bp long with a predicted open reading frame of polypeptide of 466 amino acids. Phylogenetic analysis revealed that the gene fell into the cluster of plant high-molecular-weight purple acid phosphatase. Expression analysis of the TpPAP1 in T. patula in symbiosis with Archaeospora leptoticha showed that the levels of transcripts increased eightfold by mycorrhizal colonization. Western blot analysis revealed that the 57-kDa protein corresponding to the mycorrhiza-responsive phosphatase increased by mycorrhizal colonization. The present study proposes a new strategy for acquisition of P in arbuscular mycorrhizal associations in which the fungal partner activates a part of the low-P adaptation system of the plant partner, phosphatase secretion, and improves the overall efficiency of P uptake.

Acid Phosphatase↗
PubMed1996

The total-time hypothesis and the acquisition of connected discourse as a function of mode of presentation, presentation rate, and intelligence.

This study investigated the applicability of the total-time hypothesis in learning connected discourse as a function of two separate modes of presentation, two different presentation rates, and two significantly different level of adult intelligence. The eight paragraphs of the Nelson-Denny Reading Test (Form A) served as the connected discourse. Statistical analyses showed the total-time hypothesis to be definitely applicable to the learning of the connected discourse Substantial doubt regarding the wisdom of using compressed speech technology as an educational panacea was evident.

Adult↗
PubMed1999

S-methylmethionine metabolism in Escherichia coli.

Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group from S-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed that Escherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is an S-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants in yagD which also possess defects in metE and metH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in a metE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but not S-methylmethionine in the medium reduces the amount of yagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfD and yagD products appear to reside in the acquisition of S-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis.

Aerobiosis↗
PubMed1982

Hyperlexia: precocious word recognition in developmentally delayed children.

Seven children who had unusually precocious word-recognition skills and otherwise had multiple significant developmental deviations were identified. Past findings are reviewed along with psychometric results and clinical observations of the seven hyperlexic children. Implications concerning the syndrome of hyperlexia and how this behavioral pattern may disrupt the acquisition of appropriate modalities of communication are discussed.

Adolescent↗
PubMed1999

Identification and characterization of SirA, an iron-regulated protein from Staphylococcus aureus.

The acquisition of iron by pathogenic bacteria is often a crucial step in establishing infection. To accomplish this, many bacteria, including Staphylococcus aureus, produce low-molecular-weight iron-chelating siderophores. However, the secretion and transport of these molecules in gram-positive organisms are poorly understood. The sequence, organization, and regulation of genes involved in siderophore transport are conserved among gram-negative bacteria. We used this information to identify a putative siderophore transport locus from an S. aureus genomic sequence database. This locus contains three predicted open reading frames with a high degree of homology to genes involved in siderophore uptake in several bacterial species, in particular the cbr locus of the plant pathogen Erwinia chrysanthemi. The first gene in the locus, which we have designated sir for staphylococcal iron regulated, encodes a putative lipoprotein with a molecular mass of 37 kDa. The open reading frame is preceded by a 19-bp region of dyad symmetry with homology for operator sequences controlling iron-regulated expression of genes in other bacteria. Fur titration experiments indicate that this region of dyad symmetry is sufficient for Fur-dependent regulation in Escherichia coli. The expression of this gene was repressed, in a dose-dependent manner, by the addition of iron to the S. aureus culture medium. sir-encoded proteins may be involved in iron acquisition in vivo and therefore may be targets for antimicrobial agents.

Amino Acid Sequence↗
PubMed2002

Imaging of the intracranial venous system with a contrast-enhanced volumetric interpolated examination.

A contrast-enhanced interpolated, three-dimensional (3D) gradient-echo MR sequence with asymmetric k-space sampling, which we refer to as volumetric interpolated brain examination (VIBE), was evaluated for its depiction of the normal intracranial venous system and compared with two-dimensional (2D) time-of-flight (TOF) MR venography (MRV). Fifteen subjects underwent contrast-enhanced VIBE imaging (TR/TE 8 ms/4.4 ms, flip angle 18 degrees, acquisition time, 2 min 20 s, voxel size approximately 1.5 mm(3)) and standard 2D TOF MRV (TR/TE 27 ms/9 ms, flip angle 35 degrees ). The presence of 19 venous structures per subject was assessed on maximum intensity projections (MIP) of the whole data set (whole-brain MIP) and on MIP images reconstructed spontaneously from source images (interactive MIP/source images). Results from a consensus reading where all imaging techniques and display modalities were available were taken as the standard of reference for the presence of venous structures. In addition, 10 subjects underwent both unenhanced and enhanced VIBE imaging. The value of subtracted data sets (unenhanced VIBE subtracted from enhanced VIBE) was then evaluated. Overall, VIBE provided a superior visualization of the cerebral veins than 2D TOF MRV (VIBE, sensitivity (reader 1/reader 2): 98%/99%, negative predictive value 64%/71%; TOF sensitivity: 85%/84%, negative predictive value 15%/15%; Wilcoxon signed-rank test VIBE vs TOF, p<0.001 for both readers). The VIBE interactive MIP/source images were superior to whole-brain MIP reconstructions. Image subtraction was not necessary for delineation of venous structures but improved small vein conspicuity. Contrast-enhanced VIBE acquisitions are faster and enable a visualization of the normal intracranial venous system superior to that of 2D TOF MRV.

Adolescent↗
PubMed1996

The effect of first written language on the acquisition of English literacy.

The relationship between first and second language literacy was examined by identifying the skills and processes developed in the first language that were transferred to the second language. The performance of 40 university students from The People's Republic of China, Hong Kong, Vietnam and Australia were compared on a series of tasks that assessed phonological awareness and reading and spelling skills in English. The results indicated that the Hong Kong students (with non-alphabetic first language literacy) had limited phonological awareness compared to those students with alphabetic first language literacy. The reading and spelling tasks showed no differences between the groups on real word processing. However, the students from Hong Kong had difficulty processing nonwords because of their poor phonological awareness. The results supported the hypothesis that people learning English as a second language (ESL) transfer their literacy processing skills from their first language to English. When the phonological awareness required in English had not been developed in the first language, ESL students were limited to a whole-word, visual strategy. The findings indicate that students from non-alphabetic written language backgrounds might have difficulties with new, or unfamiliar words when attending universities where English is the medium of instruction.

Adult↗
PubMed2006

Ancient lateral gene transfer in the evolution of Bdellovibrio bacteriovorus.

The recently sequenced genome of the predatory delta-proteobacterium Bdellovibrio bacteriovorus provides many insights into its metabolism and evolution. Because its genes are reasonably uniform in G+C content, it was suggested that B. bacteriovorus actively resists recombination with foreign DNA and horizontal transfer of DNA from other bacteria. To investigate this further, we carried out a variety of phylogenetic and comparative genomics analyses using data from >200 microbial genomes, including several published delta-proteobacteria. Although there might be little evidence for the extensive recent transfer of genes, we demonstrate that ancient lateral gene acquisition has shaped the B. bacteriovorus genome to a great extent.

Bdellovibrio↗
PubMed1991

Dissociable roles of the ventral, medial and lateral striatum on the acquisition and performance of a complex visual stimulus-response habit.

The effects of discrete bilateral ibotenic acid lesions to 3 areas of striatum were examined on a conditional visual discrimination task involving temporal frequency (SLOW vs FAST flashes) that had previously been shown to be sensitive to the effects of dorsal striatal dopamine depletion. Two of the groups, namely, those with nucleus accumbens (ACC) and lateral caudate-putamen (LCP) lesions, were very disrupted in the acquisition of the task. The nature of the respective impairments of the 2 groups was dissociable, however. The performance of the ACC group could be improved either by manipulations of stimulus duration or inter-stimulus interval, implying an attentional deficit. In contrast, the rats with lesions of the LCP were not significantly improved by any of the behavioural challenges. Their performance was characterised by a bias to respond to the SLOW discriminandum. Under conditions of non-reward, the LCP group extinguished their responding at a similar rate to control rats whereas the ACC group were very much more persistent. Lesions of the medial caudate-putamen failed to affect any index of performance significantly. These data suggest that the LCP is necessary for the acquisition of arbitrary stimulus-response rules and that damage to an equivalent area in humans, such as in Huntington's disease, may explain deficits of procedural memory. The second part of the experiment investigated the effects of ACC lesions on established performance of the schedule. The lesioned group behaved identically to the ACC group that had been lesioned prior to acquisition, both in terms of accuracy and degree of persistence in extinction, further implying the role of attentional factors and inflexibility in the lesion-induced deficit.

Animals↗
PubMed2004

A phage protein confers resistance to the lactococcal abortive infection mechanism AbiP.

Phage bIL66M1 is sensitive to the lactococcal abortive infection mechanism AbiP. No spontaneous AbiP-resistant variant could be obtained at a frequency of <10(-10). However, AbiP-resistant variants were readily obtained during infection with both bIL66M1 and the highly homologous AbiP-resistant phage bIL170. Gain of AbiP resistance was due to the acquisition of the e6 gene from bIL170.

Bacterial Proteins↗
PubMed1998

Effect of ease-of-acquisition on naming latency for Japanese kanji: a reanalysis of Yamazaki, et al.'s (1997) data.

Yamazaki, Ellis, Morrison, and Lambon Ralph in 1997 found two age-of-acquisition measures exerted greater independent effects on the naming latency of kanji than well-established variables such as word frequency. The current study is a sequel to that study but has reached a different conclusion. To find a better predictor than the two age-of-acquisition measures, Yamazaki, et al.'s data were reanalyzed with the new variable, ease-of-acquisition. The main finding was that the correlation between ease-of-acquisition at age 13 and naming latency was high .67 (df = 145, p < .001). The status of ease-of-acquisition and its possible role in psycholinguistic research are briefly discussed.

Adolescent↗
PubMed2002

Male strategies and Plio-Pleistocene archaeology.

Archaeological data are frequently cited in support of the idea that big game hunting drove the evolution of early Homo, mainly through its role in offspring provisioning. This argument has been disputed on two grounds: (1) ethnographic observations on modern foragers show that although hunting may contribute a large fraction of the overall diet, it is an unreliable day-to-day food source, pursued more for status than subsistence; (2) archaeological evidence from the Plio-Pleistocene, coincident with the emergence of Homo can be read to reflect low-yield scavenging, not hunting. Our review of the archaeology yields results consistent with these critiques: (1) early humans acquired large-bodied ungulates primarily by aggressive scavenging, not hunting; (2) meat was consumed at or near the point of acquisition, not at home bases, as the hunting hypothesis requires; (3) carcasses were taken at highly variable rates and in varying degrees of completeness, making meat from big game an even less reliable food source than it is among modern foragers. Collectively, Plio-Pleistocene site location and assemblage composition are consistent with the hypothesis that large carcasses were taken not for purposes of provisioning, but in the context of competitive male displays. Even if meat were acquired more reliably than the archaeology indicates, its consumption cannot account for the significant changes in life history now seen to distinguish early humans from ancestral australopiths. The coincidence between the earliest dates for Homo ergaster and an increase in the archaeological visibility of meat eating that many find so provocative instead reflects: (1) changes in the structure of the environment that concentrated scavenging opportunities in space, making evidence of their pursuit more obvious to archaeologists; (2) H. ergaster's larger body size (itself a consequence of other factors), which improved its ability at interference competition.

Adaptation, Physiological↗
PubMed1993

Molecular characterization of phosphoribosylpyrophosphate synthetase from Leishmania donovani.

The phosphoribosylpyrophosphate synthetase (PRS) enzyme from parasitic protozoa plays a critical role in the acquisition of exogenous purine bases by providing the phosphoribosylpyrophosphate substrate for phosphoribosylation. To characterize a PRS enzyme from parasitic protozoa, the prs gene was isolated from a genomic library of Leishmania donovani DNA. A 1936-bp SalI fragment was sequenced that encompassed an open reading frame of 1113 nucleotides encoding a polypeptide of 371 amino acids and 40 787 Da. After gap alignment, the leishmanial PRS exhibited 40-42% amino acid identity with a variety of mammalian and prokaryotic PRSs. L. donovani PRS also contained an approx. 20-amino acid stretch that was highly homologous to the phosphoribosylpyrophosphate binding domains of mammalian phosphoribosyltransferase enzymes. Two prs-specific transcripts of 2.6 and 2.1 kb were detected by Northern analysis, and Southern blots of genomic DNA implied that the prs locus was not tandemly repeated in the L. donovani genome. PRS activity was detected in L. donovani extracts, and apparent Km values of approx. 30 microM and approx. 1 mM were calculated for ribose-5-phosphate and ATP, respectively. PRS was sensitive to inhibition by AMP and ADP but refractory to IMP, GMP, GTP, CTP, and UTP. The high apparent Km value of the parasite enzyme for ATP and its insensitivity to inhibition by many nucleotides suggested that kinetic differences between the L. donovani and human PRSs could provide an avenue for rational therapeutic manipulation of parasitic disease. The isolation of the L. donovani prs gene now provides an opportunity to genetically dissect the determinants responsible for the function and regulation of this indispensable enzyme of purine and pyrimidine metabolism in a genus of parasitic protozoa.

Amino Acid Sequence↗
PubMed2005

Bone motion analysis from dynamic MRI: acquisition and tracking.

RATIONALE AND OBJECTIVES: For diagnosis, preoperative planning and postoperative guides, an accurate estimate of joint kinematics is required. It is important to acquire joint motion actively with real-time protocols. MATERIALS AND METHODS: We bring together MRI developments and new image processing methods in order to automatically extract active bone kinematics from multi-slice real-time dynamic MRI. We introduce a tracking algorithm based on 2D/3D registration and a procedure to validate the technique by using both dynamic and sequential MRI, providing a gold standard bone position measurement. RESULTS: We present our technique for optimizing jointly the tracking method and the acquisition protocol to overcome the trade-off in acquisition time and tracking accuracy. As a case study, we apply this methodology on a human hip joint. CONCLUSION: The final protocol (bFFE, TR/TE 3.5/1.1 ms, Flip angle 80 degrees , pixel size 4.7 x 2.6 mm, partial Fourier reduction factor of 0.65 in read direction, SENSE acceleration factor of 2, frame rate = 6.7 frames/s) provides sufficient morphological data for bone tracking to be carried out with an accuracy of 3 degrees in terms of joint angle.

Algorithms↗
PubMed1994

Transcriptional control of the yeast PDR5 gene by the PDR3 gene product.

Saccharomyces cerevisiae cells possess the ability to simultaneously acquire resistance to an array of drugs with different cytotoxic activities. The genes involved in this acquisition are referred to as pleiotropic drug resistant (PDR) genes. Several semidominant, drug resistance-encoding PDR mutations have been found that map near the centromere on chromosome II, including PDR3-1 and PDR4-1. DNA sequencing of chromosome II identified a potential open reading frame, designated YBL03-23, that has the potential to encode a protein with strong sequence similarity to the product of the PDR1 gene, a zinc finger-containing transcription factor. Here we show that YBL03-23 is allelic with PDR3. The presence of a functional copy of either PDR1 or PDR3 is essential for drug resistance and expression of a putative membrane transporter-encoding gene, PDR5. Deletion mapping of the PDR5 promoter identified a region from -360 to -112 that is essential for expression of this gene. DNase I footprinting analysis using bacterially expressed Pdr3p showed specific recognition by this protein of at least one site in the -360/-112 interval in the PDR5 promoter. A high-copy-number plasmid carrying the PDR3 gene elevated resistance to both oligomycin and cycloheximide. Increasing the number of PDR3 gene copies in a delta pdr5 strain increased oligomycin resistance but was not able to correct the cycloheximide hypersensitivity that results from loss of PDR5. These data are consistent with the notion that PDR3 acts to increase cycloheximide resistance by elevating the level of PDR5 transcription, while PDR3-mediated oligomycin resistance acts through some other target gene.

ATP-Binding Cassette Transporters↗
PubMed2006

SIRE-1, a putative plant retrovirus is closely related to a legume TY1-copia retrotransposon family.

SIRE-1 is a potential soybean retrovirus which has a gene order similar to Ty1-copia retrotransposons but also contains an envelope-like open reading frame (ORF), which is characteristic of retroviruses. PCR and Southern analysis reveals that SIRE-1 is closely related to a legume-wide family of envelope-lacking Ty1-copia group retrotransposons which suggests that SIRE-1 was formed by the recent acquisition of an envelope gene by a Ty1-copia retrotransposon.

Amino Acid Sequence↗
PubMed1999

Optimizing images of acute deep-vein thrombosis using technetium-99m-apcitide.

OBJECTIVE: The purpose of this paper is to introduce the nuclear medicine technologist to a new radiopharmaceutical, 99mTc-apcitide, for imaging acute venous thrombosis. After reading this paper, the technologist should be able to: (a) describe patient preparation for imaging with 99mTc-apcitide; (b) state the amount of 99mTc-apcitide that is administered to patients for imaging acute venous thrombosis; (c) explain patient positioning for optimal image acquisition; and (d) discuss gamma camera acquisition parameters and their importance in obtaining high-quality images. Clinical cases illustrate both the whole-body distribution and diagnostic value of 99mTc-apcitide in detecting acute deep-vein thrombosis.

Acute Disease↗