| 521. |
- Yavari, Nazila, et al.
(författare)
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In vitro measurements of optical properties of porcine brain using a novel compact device
- 2005
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Ingår i: Medical and Biological Engineering and Computing. - : Springer. - 0140-0118 .- 1741-0444. ; 43:5, s. 658-666
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the optical properties of tissues can be applied in numerous medical and scientific fields, including cancer diagnostics and therapy. There are many different ways of determining the optical properties of turbid media. The paper describes measurements of the optical properties of porcine brain tissue using novel instrumentation for simultaneous absorption and scattering characterisation of small turbid samples. Integrating sphere measurements are widely used as a reference method for determination of the optical properties of relatively thin turbid samples. However, this technique is associated with bulky equipment, complicated measuring techniques, interference compensation techniques and inconvenient sample handling. It is believed that the sphere for some applications can be replaced by a new, compact device, called the combined angular and spatially resolved head sensor, to measure the optical properties of thin turbid samples. The results compare very well with data obtained with an integrating sphere for well-defined samples. The instrument was shown to be accurate to within 12% for μa and 1% for μ s ′ in measurements of intralipid-ink samples. The corresponding variations of data were 17% and 2%, respectively. The reduced scattering coefficient for porcine white matter was measured to be 100 cm−1 at 633 nm, and the value for coagulated brain tissue was 65 cm−1. The corresponding absorption coefficients were 2 and 3 cm−1, respectively.
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| 522. |
- Zaitoun, AA, et al.
(författare)
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Quantitative studies of liver atrophy after portacaval shunt in the rat
- 2006
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 0022-4804 .- 1095-8673. ; 131:2, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- Background. It is well known that portacaval shunting ultimately leads to a decrease in liver volume and hepatic function, but the mechanism is uncertain. The aim of the present study was to evaluate the effect of portacaval shunting (PCS) upon the morphological changes that occur in the liver in rats after port caval. anastomosis. Materials and methods. Sixty-six male rats underwent either PCS (n = 35) or sham operations (n = 31). Hormone levels were determined in blood samples taken just before removal and weighing of the livers. Hematoxylin and eosin-stained sections were used for quantitative morphometric analysis. Apoptosis, mitosis, and cellular organelles also were assessed quantitatively. Results. There was a significant reduction in the liver mass together with testosterone levels in PCS rats in comparison with sham rats. The distance between presinusoidal and postsinusoidal vessels was reduced from 500 mu m in the sham rats to 299 mu m in the PCS rats (P = 0.000001). Within the same group, there was a significant reduction in the area of hepatocyte nuclei in zone 3 in comparison with zone 1. Electron microscopy revealed a highly significant (P = 0.0007) reduction in the membrane-bound cytoplasmic organelles of zone 3 hepatocytes in PCS rats in comparison with the sham rats. Apoptosis was increased in zone 3 in PCS rats (P = 0.00001), whereas in zone 1 of the same group, there was an associated increased in mitosis (P = 0.000001). Overall, the degree of apoptosis was in excess of mitosis, resulting in a general loss of liver mass. Conclusion. Morphometric analysis at cellular and subcellular levels confirms the morphological findings of liver atrophy in PCS rats. The mechanism of atrophy is a complex one. Portacaval shunting leads to hepatic atrophy that, in turn, results in microcirculatory and hormonal changes that further contribute to liver cell loss in this animal model. (C) 2006 Elsevier Inc. All rights reserved.
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| 523. |
- Zakharova, A., et al.
(författare)
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Optical absorption of polarized light in InAs/GaSb quantum wells
- 2008
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Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 23:12
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Tidskriftsartikel (refereegranskat)abstract
- Using an eight-band k p model Hamiltonian with the Burt-Foreman envelope function theory, we have investigated the optical absorption of both linearly and circularly polarized light, as well as related phenomena in InAs/GaSb broken-gap quantum wells grown along the [0 0 1] direction, with emphasis on the effects of electron-hole hybridization and the various symmetry-breaking mechanisms such as structural inversion asymmetry, bulk inversion asymmetry and interface Hamiltonian. The optical matrix elements exhibit unusual angular dependence in close connection with the spin-flip transitions which are originally forbidden. The spin split of the 2e subband results in two profound absorption peaks for the 1hh-2e transition for both linearly polarized and circularly polarized light. A large lateral optical anisotropy appears in the absorption coefficient of linearly polarized light, which can reach almost 100% with a reducing thickness of the quantum well. For the absorption of circularly polarized light, we found a large enhancement of electron spin polarization in the upper 2e subband, which was generally considered as forbidden if the polarization is along the direction perpendicular to the plane-of-light incidence. © 2008 IOP Publishing Ltd.
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| 524. |
- Zandi, Sasan, 1976-, et al.
(författare)
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EBF1 is essential for B-lineage priming and establishment of a transcription factor network in common lymphoid progenitors
- 2008
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 181:5, s. 3364-3372
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Tidskriftsartikel (refereegranskat)abstract
- Development of B-lymphoid cells in the bone marrow is a process under strict control of a hierarchy of transcription factors. To understand the development of a B-lymphoid-restricted functional network of transcription factors, we have investigated the cell autonomous role of the transcription factor EBF1 in early B cell development. This revealed that even though transplanted EBF1-deficient fetal liver cells were able to generate common lymphoid progenitors (CLPs) as well as B220(+)CD43(+)AA4.1(+) candidate precursor B cells, none of these populations showed signs of B lineage priming. The isolated CLPs were able to generate T lymphocytes in vitro supporting the idea that the phenotype of EBF1-deficient mice is restricted to the development of the B lineage. Furthermore, EBF deficient CLPs displayed a reduction in Ig H chain recombination as compared with their wild-type counterpart and essentially lacked transcription of B-lineage-associated genes. Among the genes displaying reduced expression in the EBF1 deficient CLPs were the transcription factors Pax5, Pou2af1 (OcaB), and FoxO1 that all appear to be direct genetic targets for EBF1 because their promoters contained functional binding sites for this factor. This leads us to suggest that EBF1 regulates a transcription factor network crucial for B lineage commitment.
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| 525. |
- Zhang, Fengling, et al.
(författare)
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Influence of solvent mixing on the morphology and performance of solar cells based on polyfluorene copolymer/fullerene blends
- 2006
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 16:5, s. 667-674
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the solvent on the morphol. and performance of polymer solar cells was studied in devices based on blends of the polyfluorene copolymer, poly(2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2', 1',3'-benzothiadiazole)), and [6,6]-phenyl-C61-butyric acid Me ester. The blends are spin-coated from CHCl3 or from CHCl3 mixed with small amts. of xylene, toluene, or chlorobenzene. The devices are characterized under monochromatic light and AM1.5 solar illumination. An enhancement of the photocurrent d. was obsd. in diodes made from CHCl3 mixed with chlorobenzene, and a decreased photocurrent d. is obsd. in diodes made from CHCl3 mixed with xylene or toluene, compared to diodes made from neat CHCl3. The open-circuit voltages are almost the same for all diodes. The surfaces of the active layers were imaged with AFM. Height images indicate that a finer and more uniform distribution of domains corresponds to the diodes with enhanced photocurrent that are made from CHCl3 mixed with chlorobenzene, while a structure with larger domains is assocd. with the lower photocurrents in the diodes made from CHCl3 mixed with xylene or toluene. The influence of the morphol. on the excited-state dynamics and charge generation was studied using time-resolved spectroscopy. Fast formation of bound charge pairs followed by their conversion into free charge carriers was resolved, and excitation-intensity-dependent non-geminate recombination of free charges was obsd. A significant enhancement in free-charge-carrier generation was obsd. on introducing chlorobenzene into CHCl3. Imaging photocurrent generation from the solar cells with a light-pulse technique shows an inhomogeneous photocurrent distribution, which is related to the undulations in the thickness of the active layer. Thicker parts of the diodes yield higher photocurrent values. [on SciFinder (R)]
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| 526. |
- Zhou, Ye, et al.
(författare)
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Quantitative interpretation of gold nanoparticle-based bioassays designed for detection of immunocomplex formation
- 2007
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Ingår i: BIOINTERPHASES. - : American Vacuum Society. - 1559-4106 .- 1934-8630. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- The authors present in this paper how the extended Mie theory can be used to translate not only end-point data but also temporal variations of extinction peak-position changes, Delta lambda(peak)(t), into absolute mass uptake, Gamma(t), upon biomacromolecule binding to localized surface plasmon resonance (SPR) active nanoparticles (NPs). The theoretical analysis is applied on a novel sensor template composed of a three-layer surface architecture based on (i) a self-assembled monolayer of HS(CH2)(15)COOH, (ii) a 1:1 mixture of biotinylated and pure poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), and (iii) NeutrAvidin. Assisted by independent estimations of the thickness of the three-layer architecture using quartz crystal microbalance with dissipation (QCM-D) monitoring, excellent agreement with parallel mass-uptake estimations using planar SPR is obtained. Furthermore, unspecific binding of serum to PLL-g-PEG was shown to be below the detection limit, making the surface architecture ideally suited for label-free detection of immunoreactions. To ensure that the immunocomplex formation occurred within the limited sensing depth (similar to 10 nm) of the NPs, a compact model system composed of a biotinylated human recombinant single-chain antibody fragment (empty set similar to 2 nm) directed against cholera toxin was selected. By tracking changes in the centroid (center of mass) of the extinction peak, rather than the actual peak position, signal-to-noise levels and long-term stability upon cholera toxin detection are demonstrated to be competitive with results obtained using conventional SPR and state-of-the-art QCM-D data. (C) 2007 American Vacuum Society.
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| 527. |
- Ågren, Susanna, et al.
(författare)
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Addressing spouses unique needs after cardiac surgery when recovery is complicated by heart failure
- 2009
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Ingår i: HEART and LUNG. - : Elsevier BV. - 0147-9563 .- 1527-3288. ; 38:4, s. 284-291
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac surgery places extensive stress on spouses who often are more worried than the patients themselves. Spouses can experience difficult and demanding situations when the partner becomes critically ill. OBJECTIVES: To identify, describe, and conceptualize the individual needs of spouses of patients with complications of heart failure after cardiac surgery. METHODS: Grounded theory using a mix of systematic coding, data analysis, and theoretical sampling was performed. Spouses, 10 women and 3 men between 39 and 85 years, were interviewed. RESULTS: During analysis, the core category of confirmation was identified as describing the individual needs of the spouses. The core category theoretically binds together three underlying subcategories: security, rest for mind and body, and inner strength. Confirmation facilitated acceptance and improvement of mental and physical health among spouses. CONCLUSIONS: By identifying spouses needs for security, rest for mind and body, and inner strength, health care professionals can confirm these needs throughout the caring process, from the critical care period and throughout rehabilitation at home. Interventions to confirm spouses needs are important because they are vital to the patients recovery.
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| 528. |
- Åkesson, K, et al.
(författare)
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The non-inherited maternal HLA haplotype affects the risk for type 1 diabetes
- 2009
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Ingår i: International journal of immunogenetics. - 1744-3121 .- 1744-313X. ; 36:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to test the hypothesis that the human leucocyte antigen (HLA) haplotype that is not inherited from the mother, that is, the non-inherited maternal antigen (NIMA) affects the risk for type 1 diabetes (T1D). A total of 563 children with T1D and 286 non-diabetic control children from Sweden were genotyped for DRB1, DQA1 and DQB1 alleles. The frequency of positively (DR4-DQA1*0301-B1*0302 and DR3-DQA1*0501-B1*0201), negatively (DR15-DQ A1*0102-B1*0602) or neutrally (all other) T1D associated HLA haplotypes were compared between NIMA and non-inherited paternal antigen (NIPA). All comparisons were carried out between HLA-matched patients and controls. The frequency of positively associated NIMA was higher among both DR4/X-positive healthy individuals compared wit DR4/X-positive patients (P < 0.00003) and DR3/X-positive healthy individuals compared with DR3/X-positive patients (P < 0.009). No such difference was observed for NIPA. High-risk NIMA was increased compared to NIPA among healthy DR3/X- and DR4/X-positive children (P < 0.05). There was no difference in frequency of positively associated haplotypes between patient NIMA and NIPA. The NIMA but not the NIPA affects the risk for T1D, suggesting that not only the inherited but also non-inherited maternal HLA haplotypes, perhaps through microchimerism or other mechanisms, may influence the risk for the disease.
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| 529. |
- Åsberg, Peter, et al.
(författare)
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Hydrogels from a water-soluble Zwitterionic polythiophene : dynamics under pH change and biomolecular interactions observed using quartz crystal microbalance with dissipation monitoring
- 2005
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 21:16, s. 7292-7298
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Tidskriftsartikel (refereegranskat)abstract
- The water-soluble zwitterionic polythiophene, poly(3-((S)-5-amino-5- carboxyl-3-oxapentyl)-2,5-thiophene) hydrochloride (POWT), is a conjugated polyelectrolyte (CPE) with properties well suited for biochip applications. CPEs readily form hydrogels when exposed to water-based buffer solutions or biomolecule solutions. In this work, we used in situ quartz crystal microbalance with dissipation (QCM-D) monitoring to collect information on the interaction between POWT films exposed to buffers with different pH and POWT/DNA chains. Our data show that POWT swells significantly when exposed to low-pH buffers, such as pH 4 acetate, this is seen as an increase in thickness and decrease in viscosity obtained via a Voight-based modeling of combined f and D QCM-D measurements. The magnitude of thickness and viscosity change upon changing from a pH 10 carbonate buffer to pH 4 acetate is 100% increase in thickness and 50% decrease in viscosity. The response of the hydrogel under pH change is well correlated with fluorescence data from POWT films on glass. The state of the hydrogel is important during interaction with biomolecules; illustrated by the observation that a swollen CPE hydrogel adsorbs a higher amount of DNA than a compacted one. In agreement with previous results, the QCM-D data confirmed that the POWT/DNA hydrogel sense complementary DNA specifically and with negligible binding of noncomplementary DNA. These results are important for efficient constructions of biochips in water environments using this class of materials.
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| 530. |
- Åstrand, Håkan, et al.
(författare)
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Age-related increase in wall stress of the human abdominal aorta : An in vivo study
- 2005
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Ingår i: Journal of Vascular Surgery. - : Elsevier BV. - 0741-5214 .- 1097-6809. ; 42:5, s. 926-931
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Tidskriftsartikel (refereegranskat)abstract
- Background The regulation of wall stress in the abdominal aorta (AA) of humans might be of specific interest, because the AA is the most common site for aneurysm formation in which wall stress seems to be an important pathophysiological factor. We studied the age-related changes in wall stress of the AA in healthy subjects, with the common carotid artery (CCA) as a comparison. Methods A total of 111 healthy subjects were examined with B-mode ultrasonography to determine the lumen diameter and intima-media thickness (IMT) in the AA and the CCA. Results Aortic IMT was affected by age in men and by both age and lumen diameter in women. Carotid IMT was affected by age and pulse pressure in both men and women. Wall stress was higher in the AA than in the CCA (P < .001), and men had higher wall stress than women in both the AA (P < .001) and the CCA (P < .05). Furthermore, wall stress was constant during life in the CCA of men and women and in the AA of women. In the male aorta, however, wall stress increased with age (P < 0.01). Conclusions Arterial diameters increase with age, and a compensatory thickening of the arterial wall prevents the circumferential wall stress from increasing. However, this compensatory response is insufficient in the male AA and results in an increase in stress with age. These findings might explain the propensity for aneurysms to develop in the AA of men.
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