| 1. |
- Björnsson, Jon Mar, et al.
(author)
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Reduced proliferative capacity of hematopoietic stem cells deficient in hoxb3 and hoxb4
- 2003
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In: Blood. - 0006-4971 .- 1528-0020. ; 23:11, s. 3872-3883
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Journal article (peer-reviewed)abstract
- Several homeobox transcription factors, such as HOXB3 and HOXB4, have been implicated in regulation of hematopoiesis. In support of this, studies show that overexpression of HOXB4 strongly enhances hematopoietic stem cell regeneration. Here we find that mice deficient in both Hoxb3 and Hoxb4 have defects in endogenous hematopoiesis with reduced cellularity in hematopoietic organs and diminished number of hematopoietic progenitors without perturbing lineage commitment. Analysis of embryonic day 14.5 fetal livers revealed a significant reduction in the hematopoietic stem cell pool, suggesting that the reduction in cellularity observed postnatally is due to insufficient expansion during fetal development. Primitive Lin(-) Scal(+) c-kit(+) hematopoietic progenitors lacking Hoxb3 and Hoxb4 displayed impaired proliferative capacity in vitro. Similarly, in vivo repopulating studies of Hoxb3/Hoxb4-deficient hematopoietic cells resulted in lower repopulating capability compared to normal littermates. Since no defects in homing were observed, these results suggest a slower regeneration of mutant HSC. Furthermore, treatment with cytostatic drugs demonstrated slower cell cycle kinetics of hematopoietic stem cells deficient in Hoxb3 and Hoxb4, resulting in increased tolerance to antimitotic drugs. Collectively, these data suggest a direct physiological role of Hoxb4 and Hoxb3 in regulating stem cell regeneration and that these genes are required for maximal proliferative response.
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| 2. |
- Östrand, Fredrik, et al.
(author)
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Stereoisomeric composition of the sex pheromone of the pine sawfly Microdiprion pallipes (Hym., Diprionidae)
- 2003
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In: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 13:3, s. 155-162
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Journal article (peer-reviewed)abstract
- The basic chemical structure of the sex pheromone of the pine sawfly Microdiprion pallipes (Fallen) has earlier been identified as the propionate ester of (2S,3S,7 R/S,11 R/S)/(2R,3R,7 R/S,11 R/S)-3,7,11-trimethyl-2-tridecanol. We now report the results from further investigations on the male response to individual stereoisomers and to blends of stereoisomers, both in electroantennographic (EAG) recordings and in field trapping experiments. We also present our attempts to determine the stereochemistry of the compounds present in females of M. pallipes. By comparing gas chromatograms and mass spectra obtained from natural extracts with those from synthetic compounds it was found that the females contain one or more of the four (2S,3S,7 R/S,11 R/S)-3,7,11-trimethyl-2-tridecanol isomers (SS++-1). The active pheromone component is the corresponding propionate ester 2. In EAG experiments, males responded most strongly to five propionate ester samples, namely two four-isomer blends: SS++-2 and SR++-2, and three individual stereoisomers: SSSR-, SRRR- and SRSR-2. In a series of field trapping experiments it was found that males were attracted to the SR++-2 four-isomer blend and to the individual isomer SSSR-2. Based on the EAG-recordings and field responses of males and the stereoisomers found in the females, we suggest that the propionate ester of (2S,3S,7S,11R)-3,7,11-trimethyl-2-tridecanol (SSSR-2) is used as a main component of the sex pheromone in M. pallipes. Apparently the males react to other stereoisomers in addition to that or those produced by the females.
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| 3. |
- Akos, Dennis, et al.
(author)
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Receiver measured time in the VDL mode 4 system
- 2000
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In: IEEE 2000 Position Location and Navigation Symposium. - Piscataway, NJ : IEEE Communications Society. - 0780358724 ; , s. 309-316
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Conference paper (peer-reviewed)abstract
- This paper details an investigation into the receiver measured time (RMT) concept of VDL Mode 4, basically the ability to derive estimates of time from the transmission of the VDL Mode 4 signals themselves. The RMT concept is based on determining the accurate time of transmission by measuring the time of arrival (TOA) of a received signal. The reverse aspect, or that of user position, can also be computed in the same manner and all computed simulations hold for errors in position. If synchronized time is available, or can be derived, then the user position can be computed based on signals from known transmitter locations. A complete, end-to-end RMT simulation model for the Gaussian filtered frequency shift keying (GFSK) and differential 8-phase shift keying (D8PSK) modulation techniques has been developed in which various transmitters, channels and receiver models as well as an RMT measurement system have been included. The timing results, which are included, are described in terms of two-sigma errors as a function of signal-to-noise ratios (SNRs). The performance varies for the different receiver structures over the typical operation region and for a 1-bit differential GFSK detector the two-sigma error is as low as 0.40 microseconds, corresponding to a ranging error of approximately 120 meters. When incorporating co-channel interference (CCI), multipath and Doppler frequency shifts the RMT performance has been shown to decrease in terms of higher two-sigma errors
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| 4. |
- Arvola, Mattias, 1975-, et al.
(author)
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Regulating prominence : A design pattern for co-located collaboration
- 2004
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In: Cooperative Systems Design. - Amsterdam : IOS Press. - 1586034227 ; , s. 115-130
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Conference paper (peer-reviewed)abstract
- Co-located people do things individually while participating in collaboration. It is, however, difficult for designers to foresee what they will do individually and what they will do jointly. Participants therefore need to be able to move any information object between private and public states, but that is cumbersome to do with objects confined to a traditional PC-based workstation. This paper describes a design pattern, which addresses the problem. Designers can resolve it by making a platform where users can regulate how prominent they want to make information for themselves and others. The pattern is based on field studies and design work in three different settings where desirable use qualities were identified, categorized and translated into forces in a design pattern. Conflicts between forces were noted as problems, and solutions were sought to establish a pattern. A multiple-device platform was finally derived from the pattern to provide an example of how it can be realized. It is concluded that use qualities from a qualitative analysis of technology usage can provide the empirical basis for a design pattern. This fits well with several traditions within HCI and CSCW such as ethnographically informed design, scenario-based design, and design space analysis.
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| 5. |
- Berglin, Mattias, 1970, et al.
(author)
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The adhesion of the barnacle, Balanus improvisus, to poly(dimethylsiloxane) fouling-release coatings and poly(methyl methacrylate) panels: The effect of barnacle size on strength and failure mode
- 2001
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In: Journal of Adhesion Science and Technology. - 0169-4243. ; 15:12, s. 1485-1502
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Journal article (peer-reviewed)abstract
- Measure men ts were made of the bond strength of cyprids and barnacles (Balanus improvisus) attached to poly(dimethylsiloxane) (PDMS) fouling-release coatings and poly(methyl methacrylate) (PMMA) panels as a function of barnacle base plate size (0.05-90 mm(2)). The vertical forces necessary to dislodge cyprids and newly metamorphosed barnacles (base plate < 0.5 mm(2)) were found to be equal for the two different substrates. This unexpected result was explained by the occurrence of cohesive failure in the cyprid/barnacle part. A significantly higher detachment force was observed for larger barnacles (base plate > 0.5 mm(2)) when dislodged from the PMMA compared to the PDMS. Analysis of the failure surfaces with light microscopy and scanning electron microscopy (SEM) showed a gradual transition in failure mode from a total cohesive within the barnacle to a mixed failure mode during barnacle growth. This transition. which is a measure of the balance between the cohesive strength of the barnacle base plate and the adhesion bond to the surface, occurs earlier or with smaller barnacles when detached from the PDMS. The quantification of the remaining fraction of the base plate at the polymeric failure surfaces appears to be a function of barnacle bioadhesive bond strength and is, therefore, suggested to be used as a new parameter for evaluating the release properties of new coatings formulations.
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| 6. |
- Berglund, Mattias, 1972-
(author)
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Molecular Characterization of Diffuse Large B-cell Lymphoma and Aspects of Transformation
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Lymphomas are a heterogeneous group of neoplasias originating from B- or T-lymphocytes. In this thesis, we determined the genetic and immunophenotypic characterization of DLBCL and their prognostic impact. Moreover, genomic alterations associated with the transformation to DLBCL from Hodgkin lymphoma (HL) and follicular lymphoma (FL) were elucidated. In order to outline the impact of cytogenetic as well as immunophenotypic prognostic markers in DLBCL, we firstly studied a series of 54 DLBCL tumors using comparative genomic hybridization (CGH) and we identified several frequently occurring chromosomal imbalances. Loss of 22q was more often found in the diagnostic tumors with a more advanced clinical stage, while gain of 18q21 was more commonly identified in relapses. Secondly, we correlated the expression patterns of CD10, bcl-6, IRF-4 and bcl-2 with clinical parameters in a series of 173 de novo DLBCL patients. Patients with a germinal center (GC) phenotype displayed a better survival than the non-GC group. Expression of bcl-6 and CD10 was correlated with a better survival while bcl-2 expression was associated with a poor prognosis.In approaching the HL transformation, two novel B-cell lines (U-2932 and U-2940), derived from patients with DLBCL following HL, were characterized. Interestingly, a translocation with materials from 2q and 7q as well as loss of material on 6q was found in both cell lines. For FL transformation, we assessed chromosomal alterations in a panel of 28 DLBCL patients with a previous history of FL. The DLBCL tumors displayed more chromosomal imbalances compared to FL tumors. Loss of 6q16-21 and gain of 7pter-q22 were more commonly found in the DLBCL counterparts, suggesting the chromosomal location of putative genes that may be involved in the transformation process.
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| 7. |
- Brun, Ann, et al.
(author)
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Hoxb4-deficient mice undergo normal hematopoietic development but exhibit a mild proliferation defect in hematopoietic stem cells
- 2004
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In: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 103:11, s. 4126-4133
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Journal article (peer-reviewed)abstract
- Enforced expression of Hoxb4 dramatically increases the regeneration of murine hematopoietic stem cells (HSCs) after transplantation and enhances the repopulation ability of human severe combined immunodeficiency (SCID) repopulating cells. Therefore, we asked what physiologic role Hoxb4 has in hematopoiesis. A novel mouse model lacking the entire Hoxb4 gene exhibits significantly reduced cellularity in spleen and bone marrow (BM) and a subtle reduction in red blood cell counts and hemoglobin values. A mild reduction was observed in the numbers of primitive progenitors and stem cells in adult BM and fetal liver, whereas lineage distribution was normal. Although the cell cycle kinetics of primitive progenitors was normal during endogenous hematopoiesis, defects in proliferative responses of BM Lin(-) Sca1(+) c-kit(+) stem and progenitor cells were observed in culture and in vivo after the transplantation of BM and fetal liver HSCs. Quantitative analysis of mRNA from fetal liver revealed that a deficiency of Hoxb4 alone changed the expression levels of several other Hox genes and of genes involved in cell cycle regulation. In summary, the deficiency of Hoxb4 leads to hypocellularity in hematopoietic organs and impaired proliferative capacity. However, Hoxb4 is not required for the generation of HSCs or the maintenance of steady state hematopoiesis.
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| 8. |
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| 9. |
- Fan, Xiaolong, et al.
(author)
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Transient disruption of autocrine TGF-beta signaling leads to enhanced survival and proliferation potential in single primitive human hemopoietic progenitor cells.
- 2002
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In: Journal of Immunology. - 1550-6606. ; 168:2, s. 755-762
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Journal article (peer-reviewed)abstract
- Hemopoietic stem cells (HSCs) are maintained at relative quiescence by the balance between the positive and negative regulatory factors that stimulate or inhibit their proliferation. Blocking the action of negative regulatory factors may provide a new approach for inducing HSCs into proliferation. A variety of studies have suggested that TGF-beta negatively regulates cell cycle progression of HSCs. In this study, a dominant negatively acting mutant of TGF-beta type II receptor (TbetaRIIDN) was transiently expressed in HSCs by using adenoviral vector-mediated gene delivery, such that the effects of disrupting the autocrine TGF-beta signaling in HSCs can be directly examined at a single cell level. Adenoviral vectors allowing the expression of TbetaRIIDN and green fluorescence protein in the same CD34(+)CD38(-)Lin(-) cells were constructed. Overexpression of TbetaRIIDN specifically disrupted TGF-beta-mediated signaling. Autocrine TGF-beta signaling in CD34(+)CD38(-)Lin(-) cells was studied in single cell assays under serum-free conditions. Transient blockage of autocrine TGF-beta signaling in CD34(+)CD38(-)Lin(-) cells enhanced their survival. Furthermore, the overall proliferation potential and proliferation kinetics in these cells were significantly enhanced compared with the CD34(+)CD38(-)Lin(-) cells expressing green fluorescence protein alone. Therefore, we have successfully blocked the autocrine TGF-beta-negative regulatory loop of primitive hemopoietic progenitor cells.
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| 10. |
- Gevorgian, Spartak, 1948, et al.
(author)
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Optical electromagnetic wave generator
- 2003
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Patent (other academic/artistic)abstract
- Microwaves are generated by heterodyning the outputs of two or more optical lasers which have differing central frequencies to produce beat frequencies in the microwave range. One of the beat frequencies is used to modulate the output of at least one of the lasers so as to produce sidebands which differ from the central frequency by an integral number of the sideband frequency. Each laser is connected to one of the other lasers by a weak optical link to optically injection lock the laser to the sideband of the other laser
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