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1.
Biol Res ; 55(1): 8, 2022 Feb 22.
Article in English | MEDLINE | ID: mdl-35193678

ABSTRACT

BACKGROUND: Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2-induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.


Subject(s)
Bacterial Outer Membrane Proteins/genetics , Porins , Salmonella typhimurium , Animals , Gene Expression Regulation, Bacterial , Hydrogen Peroxide/metabolism , Hydrogen Peroxide/pharmacology , Mice , Porins/genetics , Porins/metabolism , RNA, Bacterial/genetics , RNA, Bacterial/metabolism , Salmonella typhimurium/genetics , Salmonella typhimurium/metabolism
2.
Biol. Res ; 55: 8-8, 2022. ilus
Article in English | LILACS | ID: biblio-1383912

ABSTRACT

BACKGROUND: Salmonella Typhimurium is a Gram negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S . Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild type strain, suggesting that ompX mRNA is also regulated at a post transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2 induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.


Subject(s)
Animals , Mice , Salmonella typhimurium/genetics , Salmonella typhimurium/metabolism , Bacterial Outer Membrane Proteins/genetics , Porins/genetics , Porins/metabolism , RNA, Bacterial/genetics , RNA, Bacterial/metabolism , Gene Expression Regulation, Bacterial , Hydrogen Peroxide/metabolism , Hydrogen Peroxide/pharmacology
3.
Sci Total Environ ; 772: 144808, 2021 Jun 10.
Article in English | MEDLINE | ID: mdl-33770886

ABSTRACT

Off-target drift during pesticide spray applications represents a potential pathway for the introduction of active ingredient into field-adjacent water, soils, and/or vegetation. This study investigated the extent of downwind spray drift deposition of thiamethoxam (as a model insecticide) from an application of Actara® 25WG using standard nozzles (TeeJet XR11003, DG11004, and AIXR11002) onto a fallow field test site in the Midwestern USA. Single broadcast applications at a target rate of 96 g a.i./ha were made uniformly via tractor boom to a mowed stubble plot at a spray volume of 93.5 L/ha. Sampling devices (stainless steel disks, filter paper, and stainless steel rods) were located upwind of the spray swath (as negative control samples), within the spray swath (filter paper only), and downwind (all samplers), perpendicular to the spray swath from 12.5 to 400 ft. (3.8 to 122 m) from the edge of the treated field. Comparison of measured residues from the three types of samplers indicated that filter paper generally had greater variability in results than metal disks. When nozzles were compared, the AIXR11002 air induction nozzle produced less off-field deposition than other nozzles tested. Measured downwind concentrations of thiamethoxam from disk samplers were used to predict distances for mitigating potential effects to honey bees. Based on field-derived models, downwind distances from the spray swath required to reduce exposure levels below levels of concern for honey bees varied from <1 ft. to 148 ft. (0.3 to 45 m) depending on the hazard endpoint and nozzle used. These distances were considerably lower than those predicted using the AgDRIFT model, particularly for distances further downwind. At 400 ft. (122 m), AgDRIFT over-predicted the calculated concentrations by up to a factor of 4.8, 7.2, and 10 for DG11004, XR11003, and AIXR11002, respectively. These data suggest that the AgDRIFT model is less reliable for predicting spray deposition at further downwind distances, with implications for risk assessment.

4.
Sex Reprod Healthc ; 18: 37-42, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30420085

ABSTRACT

OBJECTIVE: To identify and explore processes midwives use to exercise their scope of practice whilst caring for women during normal birth. METHODS: Strauss and Corbin's (1998) grounded theory approach was used. Data were collected from 17 midwife participants using participant observation of women's labour and birth care followed by semi-structured interviews. RESULTS: The core category of promoting normal birthing: aspiring to develop a midwife-led scope of practice conceptualises midwives working to develop their scope of practice to promote and facilitate normal birthing for women. Two interrelated categories, promoting and maintaining healthy birthing and optimising scope of practice further explicate how midwives provide woman-centred care within their scope of practice. CONCLUSIONS: The theoretical framework generates conceptual knowledge of how midwives aspire to promote healthy, safe and responsive birthing care for women in their scope of practice in a hospital setting. Findings provide greater insights into the competing perspectives of birthing care challenging midwives' capacity to provide woman-centred care, influencing the degree to which midwives are able to exercise their scope of practice in promoting normal birth.


Subject(s)
Delivery, Obstetric , Hospitals , Labor, Obstetric , Midwifery , Nurse Midwives , Perinatal Care , Professional Role , Australia , Female , Grounded Theory , Humans , Pregnancy
5.
J Synchrotron Radiat ; 18(Pt 2): 266-71, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21335915

ABSTRACT

Fischer-Tropsch (FT) synthesis is an important process in the manufacturing of hydrocarbons and oxygenated hydrocarbons from mixtures of carbon monoxide and hydrogen (syngas). The reduced iron catalyst reacts with carbon monoxide and hydrogen to form bulk Fe(5)C(2) Hägg carbide (χ-HC) during FT synthesis. Arguably, χ-HC is the predominant catalyst phase present in the working iron catalyst. Deactivation of the working catalyst can be due to oxidation of χ-HC to iron oxide, a step-wise decarburization to cementite (θ-Fe(3)C), carbon formation or sintering with accompanying loss of catalytic performance. It is therefore critical to determine the precise crystal structure of χ-HC for the understanding of the synthesis process and for comparison with the first-principles ab initio modelling. Here the results of high-resolution synchrotron X-ray powder diffraction data are reported. The atomic arrangement of χ-HC was confirmed by Rietveld refinement and subsequent real-space modelling of the pair distribution function (PDF) obtained from direct Fourier transformation. The Rietveld and PDF results of χ-HC correspond well with that of a pseudo-monoclinic phase of space group Pi [a = 11.5661 (6) Å, b = 4.5709 (1) Å, c = 5.0611 (2) Å, α = 89.990 (5)°, ß = 97.753 (4)°, γ = 90.195 (4)°], where the Fe atoms are located in three distorted prismatic trigonal and one octahedral arrangement around the central C atoms. The Fe atoms are distorted from the prismatic trigonal arrangement in the monoclinic structure by the change in C atom location in the structure.

6.
Cytogenet Genome Res ; 121(3-4): 286-7, 2008.
Article in English | MEDLINE | ID: mdl-18758173

ABSTRACT

A familial duplication in the long arm of one chromosome 1 was detected due to recurrent abortions in a couple. The duplication was present in the male partner of the couple and in his mother, both clinically healthy. By reverse FISH, the duplication was determined to be located in 1q31. Multicolor banding (MCB) and application of locus-specific probes narrowed down the breakpoints to 1q31.1 and 1q32. The duplication spans a region of 13.9 Mb. None of the two breakpoints was colocalized with a known fragile site in 1q31.2, which, however, was duplicated. To the best of our knowledge, this is the first report of an unbalanced chromosome abnormality in this region that is not correlated with any clinical consequences.


Subject(s)
Chromosome Aberrations , Chromosomes, Human, Pair 1 , Chromosome Banding , Chromosomes, Artificial, Bacterial , Female , Humans , In Situ Hybridization, Fluorescence , Karyotyping , Male , Pedigree , Phenotype
7.
Clin Genet ; 73(1): 62-70, 2008 Jan.
Article in English | MEDLINE | ID: mdl-18042262

ABSTRACT

Cardio-facio-cutaneous (CFC) and Costello syndrome (CS) are congenital disorders with a significant clinical overlap. The recent discovery of heterozygous mutations in genes encoding components of the RAS-RAF-MAPK pathway in both CFC and CS suggested a similar underlying pathogenesis of these two disorders. While CFC is heterogeneous with mutations in BRAF, MAP2K1, MAP2K2 and KRAS, HRAS alterations are almost exclusively associated with CS. We carried out a comprehensive mutation analysis in 51 CFC-affected patients and 31 individuals with CS. Twelve different BRAF alterations were found in twenty-four patients with CFC (47.0%), two MAP2K1 mutations in five (9.8%) and two MAP2K2 sequence variations in three CFC-affected individuals (5.9%), whereas three patients had a KRAS alteration (5.9%). We identified four different missense mutations of HRAS in twenty-eight cases with CS (90.3%), while KRAS mutations were detected in two infants with a phenotype meeting criteria for CS (6.5%). In 14 informative families, we traced the parental origin of HRAS alterations and demonstrated inheritance of the mutated allele exclusively from the father, further confirming a paternal bias in the parental origin of HRAS mutations in CS. Careful clinical evaluation of patients with BRAF and MAP2K1/2 alterations revealed the presence of slight phenotypic differences regarding craniofacial features in MAP2K1- and MAP2K2-mutation positive individuals, suggesting possible genotype-phenotype correlations.


Subject(s)
Abnormalities, Multiple/genetics , Facies , Heart Defects, Congenital/genetics , Mutation , Skin Abnormalities/genetics , Adult , Child , DNA Mutational Analysis , Developmental Disabilities , Humans , Intellectual Disability , MAP Kinase Kinase 1/genetics , MAP Kinase Kinase 2/genetics , Phenotype , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins B-raf/genetics , Proto-Oncogene Proteins p21(ras) , Syndrome , ras Proteins/genetics
8.
Eur J Clin Microbiol Infect Dis ; 26(1): 37-42, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17180348

ABSTRACT

The aim of this study was to evaluate the synthetic C6 peptide test as a first-line test in a two-tiered scheme for Borrelia serology in a clinically well-characterized population of patients with Lyme borreliosis in Kalmar County, Sweden. The study population consisted of a prospective group (n = 200), a control group (n = 255), and a retrospective group (n = 29). The test panel consisted of the Immunetics Quick ELISA C6 Borrelia assay kit (Immunetics, Cambridge, MA, USA), the Virotech Borrelia burgdorferi ELISA (Genzyme Virotech, Rüsselsheim, Germany), and the Liaison Borrelia CLIA (DiaSorin, Saluggia, Vercelli, Italy). Seroprevalence among 200 healthy blood donors was significantly lower in the C6 test (8%) compared to the Virotech ELISA (14%) and the Liaison CLIA (12%). In convalescent sera (2-3 months and 6 months post infection) from 158 patients with erythema migrans, the seropositivity in the C6 test was also significantly lower compared to both the Virotech ELISA and the Liaison CLIA. Serosensitivity in the acute phase of erythema migrans and other clinical manifestations of borreliosis did not differ significantly between the C6 test and the Virotech ELISA or the Liaison CLIA. Overall, a positive C6 test seems to correlate well with acute borreliosis. Cross-reactivity was lower in the C6 test in sera positive for Epstein-Barr virus infection as compared to the Virotech ELISA. This study supports the use of the C6 test as a screening test for borreliosis, in endemic areas.


Subject(s)
Borrelia burgdorferi/isolation & purification , Lyme Disease/diagnosis , Reagent Kits, Diagnostic/microbiology , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Enzyme-Linked Immunosorbent Assay/methods , Erythema Chronicum Migrans/immunology , Erythema Chronicum Migrans/microbiology , Female , Humans , Lyme Disease/immunology , Male , Middle Aged , Peptides , Prospective Studies , Retrospective Studies , Sensitivity and Specificity , Serologic Tests/methods
9.
Environ Pollut ; 146(1): 34-45, 2007 Mar.
Article in English | MEDLINE | ID: mdl-16996174

ABSTRACT

The effects of limestone dust deposition on vegetation in desert ecosystems have not yet been reported. We investigated these effects in a succulent shrub from the Namib Desert at a limestone quarry near Skorpion Zinc mine (Namibia). Effects of limestone dust were determined in Zygophyllum prismatocarpum (dollar bush) plants with heavy, moderate and no visible foliar dust cover by means of chlorophyll a fluorescence measurements. Limestone dust deposition decreased overall plant performance through loss of chlorophyll content, inhibition of CO(2) assimilation, uncoupling of the oxygen-evolving complex and decreased electron transport. Importantly, dynamic recovery occurred after termination of limestone extraction at the quarry. Recovery was accelerated by rainfall, mainly because of dust removal from leaves and stimulation of new growth. These results indicate that limestone dust has severe effects on photosynthesis in desert shrubs, but that recovery is possible and that, in arid environments, this process is modulated by rainfall.


Subject(s)
Air Pollution , Industry , Photosystem II Protein Complex/metabolism , Plant Leaves/metabolism , Zygophyllum/metabolism , Biodegradation, Environmental , Calcium Carbonate , Desert Climate , Dust , Environmental Monitoring/methods , Namibia , Photosynthesis , Rain
10.
J Plant Physiol ; 161(11): 1211-24, 2004 Nov.
Article in English | MEDLINE | ID: mdl-15602813

ABSTRACT

The biochemical basis of heat/drought tolerance was investigated by comparing the response of antisense and sense transgenic soybean plants (containing the L-delta1-pyrroline-5-carboxylate reductase gene) with non-transgenic wild-type plants. The plants were subjected to a simultaneous drought and heat stress of 2 days, whereafter they were rewatered at 25 degrees C. During this time the sense plants only showed mild symptoms of stress compared to the antisense plants which were severely stressed. Upon stress, nicotinamide adenine dinucleotide phosphate (NADP+) levels decreased in antisense while it increased in sense plants. Recovery with respect to NADP+ levels was best in sense plants. Sense plants had the highest ability to accumulate proline during stress and to metabolise proline after rewatering. Analyses of the fast phase chlorophyll-a fluorescence transients showed dissociation of the oxygen-evolving complex (OEC) upon stress in all plants tested. In the sense plants, which best resisted the stress, OEC dissociation was bypassed by proline feeding electrons into photosystem 2 (PSII), maintaining an acceptable nicotinamide adenine dinucleotide hydrogen phosphate (NADPH) level, preventing further damage. Upon recovery, NADPH is consumed during oxidation of accumulated proline providing high Levels of NADP+ to act as electron acceptor to PSII, which indirectly may ameliorate the inhibition and/or the effect of uncoupling of the OEC.


Subject(s)
Acclimatization/physiology , Arabidopsis Proteins/metabolism , Glycine max/metabolism , Pyrroline Carboxylate Reductases/metabolism , Water/metabolism , Acclimatization/genetics , Arabidopsis , Arabidopsis Proteins/genetics , Chlorophyll/physiology , Chlorophyll A , DNA, Antisense/metabolism , Hot Temperature , NADP/metabolism , Photosynthesis/physiology , Plants, Genetically Modified/metabolism , Proline/metabolism , Pyrroline Carboxylate Reductases/genetics , Glycine max/genetics , delta-1-Pyrroline-5-Carboxylate Reductase
11.
Environ Monit Assess ; 99(1-3): 275-80, 2004 Dec.
Article in English | MEDLINE | ID: mdl-15641390

ABSTRACT

There has been an accelerated expansion of deserts in the past five decades. Recent data reveal that the atmogenically formed organic compound, trichloroacetic acid (TCA) is a contributory factor in addition to anthropogenic and natural sources. The aim of this study was to use TCA as an indicator for the possible occurrence of C2-chloroacetic acids; to assess the burden on the vegetation by using pine needles as a bio-indicator system and to deliberate on the possible role of TCA in the dynamics of the vegetation in southern Africa. Field experiments conducted on pine trees and on C3 and C4 crop plants under controlled laboratory conditions, have revealed that plants could be influenced positively or negatively by TCA. To obtain an integrated assessment of the pollution emission over a time span of at least one year, two-year-old pine needles of different Pinus species were used as a bio-indicator for TCA pollution at different measuring sites. The data of our investigation clearly indicate that areas exist in South Africa where the vegetation is burdened by ecotoxicologically relevant TCA contents comparable to those in central Europe and southern Russia where TCA was shown to play a role in the destabilisation of the steppe vegetation.


Subject(s)
Air Pollutants/analysis , Conservation of Natural Resources , Pinus/chemistry , Trichloroacetic Acid/analysis , Environmental Monitoring , Europe , Plant Leaves/chemistry , Russia , South Africa
12.
Mov Disord ; 16(6): 1193-5, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11748763

ABSTRACT

Voluntary palatal tremor in a patient with essential palatal tremor induced activation predominantly within regions corresponding to the inferior olive, adjacent brainstem, and dentate nuclei. Finger movements elicited only ipsilateral lobular cerebellar activation, suggesting a dysfunctional nuclear activation by palatal tremor.


Subject(s)
Essential Tremor/physiopathology , Magnetic Resonance Imaging , Palatal Muscles/physiopathology , Adult , Brain Stem/physiopathology , Cerebellar Nuclei/physiopathology , Electromyography , Essential Tremor/genetics , Humans , Male , Neural Pathways , Olivary Nucleus/physiopathology , Palate, Soft/physiopathology
13.
Magn Reson Med ; 46(4): 631-7, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11590638

ABSTRACT

The physiological noise in the resting brain, which arises from fluctuations in metabolic-linked brain physiology and subtle brain pulsations, was investigated in six healthy volunteers using oxygenation-sensitive dual-echo spiral MRI at 3.0 T. In contrast to the system and thermal noise, the physiological noise demonstrates a signal strength dependency and, unique to the metabolic-linked noise, an echo-time dependency. Variations of the MR signal strength by changing the flip angle and echo time allowed separation of the different noise components and revealed that the physiological noise at 3.0 T (1) exceeds other noise sources and (2) is significantly greater in cortical gray matter than in white matter regions. The SNR in oxygenation-sensitive MRI is predicted to saturate at higher fields, suggesting that noise measurements of the resting brain at 3.0 T and higher may provide a sensitive probe of functional information.


Subject(s)
Artifacts , Brain/anatomy & histology , Brain/physiology , Magnetic Resonance Imaging , Adult , Humans
14.
Biomaterials ; 22(17): 2371-81, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11511034

ABSTRACT

The study was aimed at examining the in vivo degradation of pure poly(D,L)lactide (PDLLA) or PDLLA with an admixture of calciumphosphates. One rod (20 x 3 x 2 mm) and one cube (3 x 2 x 2 mm) of pure PDLLA, PDLLA with tricalciumphosphate (PDLLA + TCP) or PDLLA with calciumhydrogenphosphate (PDLLA + CHP), respectively, were implanted into the dorsal muscles of 50 male Wistar Albino rats. After definite intervals (from 2nd to 72nd week), pH measurements were performed in the environment of the implants. Afterwards, the cubes with their surrounding tissues were excised for histological examinations, measurements of the outer dimensions and mechanical analyses of the explanted rods were performed. No drop of more than 0.1 pH units was detectable in the tissue surrounding any type of implants. No advantageous effect of the calciumphosphates could be proved. A mild foreign body reaction could be observed around PDLLA implants. After 72 weeks, pure PDLLA had been totally resorbed from the extracellular space, the degradation of calciumphosphate-enriched PDLLA was still in progress. A large amount of inflammations occurred in the tissues surrounding PDLLA with an admixture of slowly degrading TCP or CHP, leading to two abscesses and four fistulas at PDLLA + TCP, and two abscesses and three fistulas at PDLLA + CHP implantation site. Bending strength of pure PDLLA was constant up to the 4th week post-implantation and reduced to 60% of the initial value up to the 12th week. No traces of crystallinity could be observed during the degradation of PDLLA. As a conclusion of the study, complete resorption from the extracellular space and tissue tolerance of pure PDLLA is proved. An admixture of small calciumphosphate particles is not suitable to improve the biocompatibility of PDLLA but leads to a decrease in the mechanical characteristics.


Subject(s)
Biocompatible Materials/metabolism , Calcium Phosphates/metabolism , Polyesters/metabolism , Animals , Biocompatible Materials/chemistry , Biodegradation, Environmental , Calcium Phosphates/chemistry , Elasticity , Fracture Fixation, Internal , Male , Materials Testing , Microscopy, Electron, Scanning , Molecular Weight , Polyesters/chemistry , Prostheses and Implants , Rats , Rats, Wistar , Stress, Mechanical
15.
Magn Reson Imaging ; 19(1): 13-20, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11295341

ABSTRACT

Cerebral blood flow (CBF) and oxygenation changes following both a simple breath holding test (BHT) and a CO(2) challenge can be detected with functional magnetic resonance imaging techniques. The BHT has the advantage of not requiring a source of CO(2) and acetazolamide and therefore it can easily be performed during a routine MR examination. In this study we compared global hemodynamic changes induced by breath holding and CO(2) inhalation with blood oxygenation level dependent (BOLD) and CBF sensitized fMRI techniques. During each vascular challenge BOLD and CBF signals were determined simultaneously with a combined BOLD and flow-sensitive alternating inversion recovery (FAIR) pulse sequence. There was a good correlation between the global BOLD signal intensity changes during breath holding and CO(2) inhalation supporting the notion that the BHT is equivalent to CO(2) inhalation in evaluating the hemodynamic reserve capacity with BOLD fMRI. In contrast, there was no correlation between relative CBF changes during both vascular challenges, which was probably due to the reduced temporal resolution of the combined BOLD and FAIR pulse sequence.


Subject(s)
Carbon Dioxide/blood , Carbon Dioxide/physiology , Cerebrovascular Circulation/physiology , Magnetic Resonance Imaging , Oxygen/blood , Oxygen/physiology , Telencephalon/anatomy & histology , Telencephalon/physiology , Adult , Female , Humans , Male , Reference Values
16.
Magn Reson Med ; 45(4): 595-604, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11283987

ABSTRACT

Noise properties, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal responses were compared during functional activation of the human brain at 1.5 and 3.0 T. At the higher field spiral gradient-echo (GRE) brain images revealed an average gain in SNR of 1.7 in fully relaxed and 2.2 in images with a repetition time (TR) of 1.5 sec. The tempered gain at longer TRs reflects the fact that the physiological noise depends on the signal strength and becomes a larger fraction of the total noise at 3.0 T. Activation of the primary motor and visual cortex resulted in a 36% and 44% increase of "activated pixels" at 3.0 T, which reflects a greater sensitivity for the detection of activated gray matter at the higher field. The gain in the CNR exhibited a dependency on the underlying tissue, i.e., an increase of 1.8x in regions of particular high activation-induced signal changes (presumably venous vessels) and of 2.2x in the average activated areas. These results demonstrate that 3.0 T provides a clear advantage over 1.5 T for neuroimaging of homogeneous brain tissue, although stronger physiological noise contributions, more complicated signal features in the proximity of strong susceptibility gradients, and changes in the intrinsic relaxation times may mediate the enhancement. Magn Reson Med 45:595-604, 2001.


Subject(s)
Brain/anatomy & histology , Magnetic Resonance Imaging/methods , Brain/physiology , Humans , Motor Cortex/physiology , Oxygen , Visual Cortex/physiology
17.
Aust J Midwifery ; 14(2): 12-7, 2001 Jun.
Article in English | MEDLINE | ID: mdl-12760011

ABSTRACT

A quality improvement project was conducted by a major maternity provider (3000 births per year) in the western suburbs of Melbourne. The first part of the project explored the reasons for increased length of stay (LOS), beyond the average timeframe for women receiving postnatal care. The perceptions of 100 women on their length of stay was also measured in the second part of the project. Two information audits were conducted to explore reasons for increased LOS. These reasons were varied, and by the time of the second audit, there was a demonstrated reduction in LOS. A Length of Stay Questionnaire was used to investigate women's perceptions of their LOS on discharge from hospital, and by telephone follow-up 14 days post-discharge. Perceptions varied between women and related to issues such as individual health complications, models of care, postnatal education, and degree of support at home. This project has implications for postnatal midwifery care in relation to discharge planning and women's expectations of care following birth.


Subject(s)
Health Knowledge, Attitudes, Practice , Length of Stay/statistics & numerical data , Postnatal Care/statistics & numerical data , Female , Humans , Infant, Newborn , Infant, Newborn, Diseases/epidemiology , Medical Audit , Midwifery/methods , Outcome and Process Assessment, Health Care , Patient Education as Topic/standards , Patient Satisfaction , Pregnancy , Puerperal Disorders/epidemiology , Surveys and Questionnaires , Victoria/epidemiology
19.
Radiology ; 216(1): 279-83, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10887262

ABSTRACT

The authors performed thermoacoustic computed tomography (CT) with 434-MHz radio waves in five patients with documented breast cancer. Three of the patients underwent imaging before chemotherapy was initiated and two at the conclusion of their primary chemotherapy. In the former three patients, thermoacoustic CT demonstrated contrast enhancement in the region of the tumor. In the latter two patients, no contrast enhancement was seen, and pathologic examination after surgical resection of the area of original tumor confirmed complete remission of disease.


Subject(s)
Breast Neoplasms/diagnostic imaging , Tomography, X-Ray Computed/methods , Acoustics , Adult , Aged , Breast Neoplasms/drug therapy , Feasibility Studies , Female , Humans , Mammography , Middle Aged , Radio Waves , Tomography, X-Ray Computed/instrumentation
20.
J Pharm Sci ; 89(7): 910-9, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10861592

ABSTRACT

We have incorporated daunomycin, an antineoplastic agent, into a biodegradable hydrogel through a labile covalent bond. In brief, sodium alginate was chemically broken down to low molecular weight and followed by oxidation to prepare poly(aldehyde guluronate). Adipic dihydrazide was used to incorporate the drug into the polymer backbone and cross-link the polymer to form hydrogels. Daunomycin can be released from the hydrogel after the hydrolysis of the covalent linkage between the drug and the polymer. A wide range of release profiles of daunomycin (e.g., from 2 days to 6 weeks) has been achieved using these materials, and the biological activity of the released daunomycin was maintained.


Subject(s)
Aldehydes/chemistry , Antibiotics, Antineoplastic/administration & dosage , Daunorubicin/administration & dosage , Polysaccharides/chemistry , Antibiotics, Antineoplastic/chemistry , Antibiotics, Antineoplastic/pharmacology , Biological Availability , Carbohydrate Sequence , Cell Survival/drug effects , Cross-Linking Reagents , Daunorubicin/chemistry , Daunorubicin/pharmacology , Delayed-Action Preparations , Humans , Hydrogel, Polyethylene Glycol Dimethacrylate , Hydroxamic Acids/chemistry , KB Cells , Molecular Sequence Data , Solubility , Spectrophotometry, Ultraviolet
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