| 1. |
- Clarke, Robert, et al.
(author)
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Lowering blood homocysteine with folic acid based supplements : Meta-analysis of randomised trials
- 1998
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In: British Medical Journal. - : BMJ. - 0959-8146. ; 316:7135, s. 894-898
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Research review (peer-reviewed)abstract
- Objective: To determine the size of reduction in homocysteine concentrations produced by dietary supplementation with folic acid and with vitamins B-12 or B-6. Design: Meta-analysis of randomised controlled trials that assessed the effects of folic acid based supplements on blood homocysteine concentration. Multivariate regression analysis was used to determine the effects on homocysteine concentrations of different doses of folic acid and of the addition of vitamin B-12 or B-6. Subjects: Individual data on 1114 people included in 12 trials. Findings: The proportional and absolute reductions in blood homocysteine produced by folic acid supplements were greater at higher pretreatment blood homocysteine concentrations (P < 0.001) and at lower pretreatment blood folate concentrations (P < 0.001). After standardisation to pretreatment blood concentrations of homocysteine of 12 μmol/l and of folate of 12 nmol/l (approximate average concentrations for Western populations), dietary folic acid reduced blood homocysteine concentrations by 25% (95% confidence interval 23% to 28%; P < 0.001), with similar effects in the range of 0.5-5 mg folic acid daily. Vitamin B-12 (mean 0.5 mg daily) produced an additional 7% (3% to 10%) reduction in blood homocysteine. Vitamin B-6 (mean 16.5 mg daily) did not have a significant additional effect. Conclusions: Typically in Western populations, daily supplementation with both 0.5-5 mg folic acid and about 0.5 mg vitamin B-12 would be expected to reduce blood homocysteine concentrations by about a quarter to a third (for example, from about 12 μmol/l to 8-9 μmol/l). Large scale randomised trials of such regimens in high risk populations are now needed to determine whether lowering blood homocysteine concentrations reduces the risk of vascular disease.
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| 2. |
- West, Jay B., et al.
(author)
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Comparison and evaluation of retrospective intermodality image registration techniques
- 1997
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In: SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. ; , s. 332-347
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Conference paper (peer-reviewed)abstract
- All retrospective image registration methods have attached to them some intrinsic estimate of registration error. However, this estimate of accuracy may not always be a good indicator of the distance between actual and estimated positions of targets within the cranial cavity. This paper describes a project whose principal goal is to use a prospective method based on fiducial markers as a ’gold standard’ to perform an objective, blinded evaluation of the accuracy of several retrospective image-to-image registration techniques. Image volumes of three modalities – CT, MR, and PET – were taken of patients undergoing neurosurgery at Vanderbilt University Medical Center. These volumes had all traces of the fiducial markers removed, and were provided to project collaborators outside Vanderbilt, who then performed retrospective registrations on the volumes, calculating transformations from CT to MR and/or from PET to MR, and communicated their transformations to Vanderbilt where the accuracy of each registration was evaluated. In this evaluation the accuracy is measured at multiple ’regions of interest,’ i.e. areas in the brain which would commonly be areas of neurological interest. A region is defined in the MR image and its centroid C is determined. Then the prospective registration is used to obtain the corresponding point C’ in CT or PET. To this point the retrospective registration is then applied, producing C’ in MR. Statistics are gathered on the target registration error (TRE), which is the disparity between the original point C and its corresponding point C’. A second goal of the project is to evaluate the importance of correcting geometrical distortion in MR images, by comparing the retrospective TRE in the rectified images, i.e., those which have had the distortion correction applied, with that of the same images before rectification. This paper presents preliminary results of this study along with a brief description of each registration technique and an estimate of both preparation and execution time needed to perform the registration.
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| 5. |
- Jönsson, Anders, 1959, et al.
(author)
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Effects of amide local anaesthetics on eicosanoid formation in burned skin.
- 1999
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In: Acta anaesthesiologica Scandinavica. - 0001-5172. ; 43:6, s. 618-22
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Journal article (peer-reviewed)abstract
- Previous studies have demonstrated potent inhibition of burn oedema and progressive ischaemia by local anaesthetics. Since eicosanoids have been suggested to play an important role in the pathophysiology of burns, we compared in the present ex vivo study the effects of topical lidocaine/prilocaine cream (EMLA, ASTRA, Sweden) and intravenous lidocaine with that of saline on eicosanoid formation by normal and burned rat skin.
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| 6. |
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| 7. |
- Pettersson, Leif A. A.
(author)
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Optical Modeling and Characterization of Layers and Multilayer Structures : Organic Optoelectronic Devices and Spectroscopic Ellipsometry
- 1999
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Doctoral thesis (other academic/artistic)abstract
- This dissertation is on the subject of modeling and characterization of layers and multilayer structures with respect to their optical properties and characteristics. A number of different systems have been investigated; among them multilayer structures in the form of organic optoelectronic devices, anisotropic layers of conjugated polymers as well as inhomogeneous layers of porous silicon and oxidized silver.Modeling of the optical characteristics of organic optoelectronic devices includes organic photovoltaic devices and organic light-emitting diodes. Experimental short-circuit photocurrent action spectra of poly(3-( 4' -(1",4",7"-trioxaoctyl)phenyl)thiophene) (PEOPT)/fullerene (C60) thin film heterojunction photovoltaic devices were modeled. The modeling was based on the assumption that the photocurrent generation process is the result of creation and diffusion of photogenerated species (excitons), which are dissociated by charge transfer at the PEOPT/C60 interface. At the modeling, exciton diffusion ranges of PEOPT and C60 were obtained and the influence of the geometrical structure with respect to the efficiency of the thin film devices were studied. In addition, an analysis of the internal monochromatic quantum efficiency of organic photovoltaic devices based on poly(3-( 4-octylphenyl)-2,2' -bithiophene) (PTOPT) layers and PTOPT/C60 bilayers were presented. A quantum efficiency of exciton-to-charge generation is defined as the external monochromatic quantum efficiency normalized to the absorption in the active materials of the device. An upper limit of the efficiency can be determined and results show that much of the light is absorbed in photoactive layers of the device whereas only a fraction of the generated excitons is converted to charge carriers and can be collected as photocurrent. Optical characteristics of bilayer organic light-emitting diodes made of poly(3-methyl-4 -octylthiophene) and 2-(biphenylyl)-5-(4-tertbutylphenyl)-1,2,4-oxadiazole layers bet ween electrodes of indium tin oxide and Ca/ Al were also modeled. These model simulations, together with electrochemical measurements, can be interpreted as evidence for an indirect optical transition at the polymer/molecule interface that only occurs in a strong electric field.Anisotropic layers of poly(3,4-ethylenedioxythiophene) doped with toluenesulfonate and poly(4-styrenesulfonate) as well as layers of poly(p-pyridine) were studied. Techniques used in these studies were in the firstplace spectroscopic ellipsometry, but also polarized transmission spectrophotometry, grazing x-ray diffraction, and infrared spectroscopy. Common features of these layers were that they all exhibited uniaxial anisotropy with the optic axis perpendicular to the layer surface. Inhomogeneous layers of porous silicon and oxidized silver were also studied by spectroscopic ellipsometry. In the case of porous silicon, analyses revealed a compositional gradient normal to the surface. A porosity graded layer model was presented and used in the analysis of the material. In the porosity graded layer model, the inhomogeneous layer was built up by a number of thin sublayers with the porosity slightly changing from one sublayer to the next. Complementary studies were performed with crosssectional transmission electron microscopy. Finally, silver oxide and the oxidation process of silver layers were studied with both in situ and ex situ spectroscopic ellipsometry. In the evaluation of experimental optical data of anisotropic and inhomogeneous layers, techniques such as acquiring data at multiple wavelengths and angles of incidence are of great value to enhancethe optical information content of measured data. Furthermore, inclusion of multiple data types and simultaneous analysis of multiple samples are very powerful ways to enhance the optical information content and to eliminate strong parameter correlation from complex models.
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| 8. |
- Pugliese, Alberto, et al.
(author)
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Sequence analysis of the diabetes-protective human leukocyte antigen-DQB1*0602 allele in unaffected, islet cell antibody-positive first degree relatives and in rare patients with type 1 diabetes
- 1999
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In: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 84:5, s. 1722-1728
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Journal article (peer-reviewed)abstract
- The human leukocyte antigen (HLA)-DQA1*0102/DQB1*0602/DRB1*1501 (DR2) haplotype confers strong protection from type 1 diabetes. Growing evidence suggests that such protection may be mostly encoded by the DQB1*0602 allele, and we reported that even first degree relatives with islet cell antibodies (ICA) have an extremely low diabetes risk if they carry DQB1*0602. Recently, novel variants of the DQB1*0602 and *0603 alleles were reported in four patients with type 1 diabetes originally typed as DQB1*0602 with conventional techniques. One inference from this observation is that DQB1*0602 may confer absolute protection and may never occur in type 1 diabetes. By this hypothesis, all patients typed as DQB1*0602 positive with conventional techniques should carry one of the above diabetes-permissive variants instead of the protective DQB1*0602. Such variants could also occur in ICA/DQB1*0602-positive relatives, with the implication that their diabetes risk could be significantly higher than previously estimated. We therefore sequenced the DQB1*0602 and DQA1*0102 alleles in all ICA/DQB1*0602-positive relatives (n = 8) previously described and in six rare patients with type 1 diabetes and DQB1*0602. We found that all relatives and patients carry the known DQB1*0602 and DQA1*0102 sequences, and none of them has the mtDNA A3243G mutation associated with late-onset diabetes in ICA-positive individuals. These findings suggest that diabetes-permissive DQB1*0602/3 variants may be very rare. Thus, although the protective effect associated with DQB1*0602 is extremely powerful, it is not absolute. Nonetheless, the development of diabetes in individuals with DQB1*0602 remains extremely unlikely, even in the presence of ICA, as confirmed by our further evaluation of ICA/DQB1*0602-positive relatives, none of whom has yet developed diabetes.
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| 9. |
- Shi, Jinrui, et al.
(author)
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Identification of cDNA clones encoding vasolin-containing protein and other plant plasma membrane-associated proteins by a general immuno-screening strategy.
- 1995
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In: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 92, s. 4457-4461
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Journal article (peer-reviewed)abstract
- An approach was developed for the isolation and characterization of soybean plasma membrane-associated proteins by immunoscreening of a cDNA expression library. An antiserum was raised against purified plasma membrane vesicles. In a differential screening of approximately 500,000 plaque-forming units with the anti-(plasma membrane) serum and DNA probes derived from highly abundant clones isolated in a preliminary screening, 261 clones were selected from approximately 1,200 antiserum-positive plaques. These clones were classified into 40 groups by hybridization analysis and 5'- and 3'-terminal sequencing. By searching nucleic acid and protein sequence data bases, 11 groups of cDNAs were identified, among which valosin-containing protein (VCP), clathrin heavy chain, phospholipase C, and S-adenosylmethionine:delta 24-sterol-C-methyltransferase have not to date been cloned from plants. The remaining 29 groups did not match any current data base entries and may, therefore, represent additional or yet uncharacterized genes. A full-length cDNA encoding the soybean VCP was sequenced. The high level of amino acid identity with vertebrate VCP and yeast CDC48 protein indicates that the soybean protein is a plant homolog of vertebrate VCP and yeast CDC48 protein.
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| 10. |
- Ahlberg-Hultén, Gunnel, 1952-
(author)
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Psychological Demands and Decision Latitude Within Health Care Work : Relation to Health and Significance
- 1999
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Doctoral thesis (other academic/artistic)abstract
- The general aim of this thesis is to provide a scientific evaluation of the psychosocial work environment for health care personnel. The theoretical basis is the demand-control model developed by Karasek and Theorell. The model consists of the dimensions psychological demands and decision latitude, the latter is a combination of intellectual discretion and authority over decision.The results in study I indicated that there are strong relationships between job strain, high psychological demands and low decision latitude, and blood pressure during work among health care personnel. In study II, symptoms from the low back were associated with all three dimensions psychological demands, skill discretion and decision authority while symptoms from the neck were related to lack of work support. The results in study III indicated that the combination of somatic and psychiatric care could be associated with higher levels of job strain and psychological symptoms.Study IV showed that substantial changes in working conditions had been frequent in the public sector during the period 1988-1996 and that registered nurses and nurse assistants had very different developments. Registered nurses had got a more intense work environment with increased skill utilization but also increased hindrances to perform work. Nurse assistants on the other hand had experienced decreased skill utilization. Temporary employment and part time work, common among health care personnel with low education, were the factors that explained the greatest part of deterioration of skill utilization and possibility to take part in planning of work. These different trends may negatively influence social climate as these two occupational groups often work together.Study V is a qualitative validation of the demand-control model. The findings showed that the model is equally relevant for women as for men and also relevant for health care personnel. Compared to occupational groups working with either "things" or "symbols" health care personnel experienced higher levels of psychological demands and lower levels of decision latitude.It is concluded that the demand-control scale is relevant for use in studies of psychosocial work environment in health care, possibly supplemented with the effort-reward scale. In order to reach a more solid understanding of the psychosocial work environment, questionnaire data should be combined with qualitatively analyzed interviews. The indications of a deteriorated psychosocial work environment for health care personnel in this and other studies calls for radical changes that promote less psychological demands and more decision latitude within this occupational sector.
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