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- Szigyarto, Cristina, et al.
(author)
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A matrix-located processing peptidase of plant mitochondria.
- 1998
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In: Plant Molecular Biology. - 0167-4412 .- 1573-5028. ; 36:1
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Journal article (peer-reviewed)abstract
- Nuclear-encoded mitochondrial precursor proteins are proteolytically processed inside the mitochondrion after import. The general mitochondrial processing activity in plant mitochondria has been shown to be integrated into the cytochrome bc1 complex of the respiratory chain. Here we investigate the occurrence of an additional, matrix-located processing activity by incubation of the precursors of the soybean mitochondrial proteins, alternative oxidase, the FAd subunit of the ATP synthetase and the tobacco F1 beta subunit of the ATP synthase, with the membrane and soluble components of mitochondria isolated from soybean cotyledons and spinach leaves. A matrix-located peptidase specifically processed the precursors to the predicted mature form in a reaction which was sensitive to orthophenanthroline, a characteristic inhibitor of mitochondrial processing peptidase (MPP). The specificity of the matrix peptidase was illustrated by the inhibition of processing of the alternative oxidase precursor in both soybean and spinach matrix extracts upon altering a single amino acid residue in the targeting presequence (-2 Arg to Gly). Additionally, there was no evidence for general proteolysis of precursor proteins incubated with the matrix. The purity of the matrix fractions was ascertained by spectrophotometric and immunological analyses. The results demonstrate that there is a specific processing activity in the matrix of soybean and spinach in addition to the previously well characterized membrane-bound MPP integrated into the cytochrome bcl complex of the respiratory chain.
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- Björk-Eriksson, Thomas, 1960, et al.
(author)
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The in vitro radiosensitivity of human head and neck cancers
- 1998
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In: Br J Cancer. - 0007-0920. ; 77:12, s. 2371-5
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Journal article (peer-reviewed)abstract
- A study was made of the intrinsic radiosensitivity of 140 biopsy and surgical specimens of malignant head and neck tumours of different histologies. Using a soft-agar clonogenic assay, the material was assessed for the ability to grow in culture (colony-forming efficiency; CFE) and inherent tumour radiosensitivity (surviving fraction at 2 Gy, SF2). The success rate for obtaining growth was 74% (104/140) with a mean CFE of 0.093% (median 0.031) and a range of 0.002-1.3%. SF2 was obtained for 88 of 140 specimens, representing a success rate of 63% with a mean SF2 of 0.48 (median 0.43) and a range of 0.10-1.00. There were no significant differences in radiosensitivity between different sites of the head and neck region. There were no significant relationships between SF2 and disease stage, nodal status, tumour grade, patient age, primary tumour growth pattern and CFE. The results were compared with those for other tumour types previously analysed with the same assay. The distribution of the SF2 values for the head and neck tumours was similar to that for 145 cervix carcinomas and there was no significant difference in mean radiosensitivity between the two tumour types. Also, there was no significant difference in radiosensitivity between head and neck tumours and either breast or colorectal cancers. However, a group of eight lymphomas was significantly more radiosensitive. These results confirm the feasibility of carrying out radiosensitivity measurements using a soft-agar clonogenic assay on head and neck tumours. In addition, the work has shown that radiosensitivity is independent of many clinical parameters and that the mean value is similar to that reported for cervix carcinomas.
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| 4. |
- Eudy, James D., et al.
(author)
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Mutation of a gene encoding a protein with extracellular matrix motifs in Usher syndrome type IIa
- 1998
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 280:5370, s. 1753-1757
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Journal article (peer-reviewed)abstract
- Usher syndrome type IIa (OMIM 276901), an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa, maps to the long arm of human chromosome 1q41 between markers AFM268ZD1 and AFM144XF2. Three biologically important mutations in Usher syndrome type IIa patients were identified in a gene (USH2A) isolated from this critical region. The USH2A gene encodes a protein with a predicted size of 171.5 kilodaltons that has laminin epidermal growth factor and fibronectin type III motifs; these motifs are most commonly observed in proteins comprising components of the basal lamina and extracellular matrixes and in cell adhesion molecules.
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| 6. |
- Malmgren, Tord G.M. 1969-
(author)
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Search for a Neutral Higgs Boson with DELPHI
- 1998
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Doctoral thesis (other academic/artistic)abstract
- The mass of the neutral Higgs boson cannot be predicted by the Standard Model. Therefore, the particle is scanned for at different assumed masses. The search described here was done using data taken with the DELPHI detector during 1993-1994 (Ecm=91 GeV), 1996 (Ecm=161 and 172 GeV) and during 1997 (Ecm=183 GeV).The Higgs boson was searched for through the Bjorken process where the decay of the Z* into two neutrinos was assumed. In order to reduce the background to a level where a discovery would be possible, new analysis methods using discriminant analysis were developed. This led to a very good background rejection and high signal efficiency. One event, with a mass of 27.5±3.6 GeV/c2, was selected from the 1993 real data at Ecm=91 GeV; one event, mH=64.6+2.4-1.2 GeV/c2, from 1996 at Ecm=161 GeV; and one event, mH=88 GeV/c2, from 1997.In the absence of a clear signal, these results were translated into a limit on the Higgs boson mass mH>58.3 GeV/c2 with 1993 data, verified with 1994 data, mH>64.6 GeV/c2 with 1996 data, and mH>85.7 GeV/c2 with 1997 data; all at 95% confidence level.
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