| 1. |
- Bengtsson, G. J, et al.
(författare)
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Natural Lifetimes of Excited-states of Neutral Nitrogen Determined By Time-resolved Laser Spectroscopy
- 1992
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 45:5, s. 2712-2715
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes were determined for three quartet states of neutral nitrogen, and sequences of Rydberg states were studied using depletion spectroscopy. Free nitrogen atoms were generated by photodissociation of N2O using frequency-tripled dye-laser radiation that was two-photon resonant with the 2p(2)3p 4S or 4D states. Further quartet states were reached by a subsequent single-photon absorption. We obtain tau(2p(2)3p 4D7/2) = 44(2) ns, tau(2p(2)3p 4S3/2) = 26.0(1.5) ns, and tau(2p(2)6s4P5/2) = 41(7) ns.
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| 2. |
- Dudman, N. P. B., et al.
(författare)
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Disordered methionine/homocysteine metabolism in premature vascular disease. Its occurrence, cofactor therapy, and enzymology
- 1993
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - : American Heart Association. - 1079-5642 .- 1524-4636. ; 13:9, s. 1253-1260
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Tidskriftsartikel (refereegranskat)abstract
- Mild homocysteinemia occurs surprisingly often in patients with premature vascular disease. We studied the possible enzymatic sources of this mild hyperhomocysteinemia and the control of homocysteine levels in plasma by treatment of patients with the cofactors and cosubstrates of homocysteine catabolism. We assessed homocysteine metabolism in 131 patients who had premature disease in their coronary, peripheral, or cerebrovascular circulation by using a standard oral methionine-load test. Impaired homocysteine metabolism occurred in 28 patients. We assayed levels of the primary enzymes of homocysteine catabolism in cultured skin fibroblast extracts from 15 of these 28 patients. The patients' cystathionine beta-synthase levels (3.68 +/- 2.52 nmol/h per milligram of cell protein, mean +/- SD) were markedly depressed compared with those from 31 healthy adult control subjects (7.61 +/- 4.49, P < .001). The patients' levels of 5-methyltetrahydrofolate: homocysteine methyltransferase were normal. While betaine: homocysteine methyltransferase was not expressed in skin fibroblasts, 24-hour urinary betaine and N,N-dimethylglycine measurements were consistent with normal or enhanced remethylation of homocysteine by betaine: homocysteine methyltransferase in the 13 patients tested. When treated daily with choline and betaine, pyridoxine, or folic acid, there was a normalization of the postmethionine plasma homocysteine level in 16 of 19 patients. Our results indicate that mild homocysteinemia in premature vascular disease may be caused by either a folate deficiency or deficiencies in cystathionine beta-synthase activity. It does not necessarily involve deficiencies of either 5-methyltetrahydrofolate:homocysteine methyltransferase or betaine:homocysteine methyltransferase. Effective treatment regimens are also defined.
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| 3. |
- Hsu, D. S., et al.
(författare)
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FLOW LINEAR DICHROISM AND ELECTRON-MICROSCOPIC ANALYSIS OF PROTEIN-DNA COMPLEXES OF A MUTANT UVRB PROTEIN THAT BINDS TO BUT CANNOT KINK DNA
- 1994
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 241:5, s. 645-650
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Tidskriftsartikel (refereegranskat)abstract
- (A)BC excinuclease of Escherichia coli is the enzymatic activity resulting from sequential and partially overlapping actions of UvrA, UvrB, and UvrC protein. UvrA is a molecular matchmaker which promotes the formation of a stable UvrB-damaged DNA complex in which the DNA is kinked by about 130 degrees. The UvrB-DNA complex is then recognized by UvrC) and two incisions are made in the DNA by the joint actions of UvrC and UvrB. A mutant of UvrB (D478A) can be loaded onto the DNA but it does not interact with UvrC to cause a nick 3' to the lesion. Based on the lack of a DNase-I-hypersensitive site in the footprint of the mutant, it was proposed that the lack of incision was due to the inability of the mutant UvrB to kink the DNA. In the current study we have investigated the interaction of the mutant UvrB with DNA using two biophysical methods, flow linear dichroism and electron microscopy. Both methods reveal that the mutant UvrB is unable to bend DNA.
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| 4. |
- HUGHES, JR, et al.
(författare)
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LIFETIME MEASUREMENTS IN THE REGULAR DELTA-I = 1 OBLATE BAND IN PB-197
- 1993
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 48:5, s. R2135-R2139
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of states in the regular DELTAI = 1 band in 197Pb have been measured with the Doppler-shift attenuation method. Excited states in 197Pb were populated using the Sm-154(48Ca, 5n) reaction at E(b) = 210 MeV. The target consisted of 1 mg/cm2 Sm-154 evaporated onto a 10 mg/cm2 Au backing. Discernible lineshapes for gamma rays in the energy range 300 < E(gamma) < 500 keV in the regular band were observed in a spectroscopic study with the 20 Ge-detector array, HERA. Level lifetimes were obtained from a lineshape analysis. Averaged reduced transition strengths, B(M1) approximately 1.7 W.u. and B(E2) approximately 18 W.u., are deduced and these are compared with theoretical predictions for the suggested configuration of this band.
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| 5. |
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| 6. |
- Svanberg, Katarina, et al.
(författare)
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Photodynamic Therapy of Nonmelanoma Malignant-tumors of the Skin Using Topical Delta-amino Levulinic Acid Sensitization and Laser Irradiation
- 1994
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Ingår i: British Journal of Dermatology. - : Oxford University Press (OUP). - 1365-2133 .- 0007-0963. ; 130:6, s. 743-751
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Tidskriftsartikel (refereegranskat)abstract
- Eighty basal cell carcinomas (BCCs) in 21 patients, 10 lesions of Bowen's disease in three patients, and four lesions of cutaneous T-cell lymphoma in two patients, were treated with photodynamic laser therapy (PDT), using topical application of the haem precursor delta-amino levulinic acid (ALA). The diagnoses were confirmed histologically prior to treatment. Fifty-five of the BCCs were superficial lesions, and 25 were nodular. Of the 80 BCCs, 39 (49%) were located on the trunk, 36 (45%) on the head and neck region, four (15%) on the leg and one on the arm. The two principal locations of the 10 Bowen's disease lesions were the leg (50%) and the trunk (40%). The T-cell lymphoma lesions were located on the shoulder and on the arm. A water-in-oil based cream containing 20% ALA was applied to the lesions, with a margin of about 10-20 mm beyond the visible tumour border, 4-6 h before the laser procedure. During this period of time the highly fluorescent and photodynamically active substance protoporphyrin IX (Pp IX) is synthesized via the haem cycle. Laser-induced fluorescence (LIF) was used for real-time monitoring of the Pp IX distribution in the tumour and in the normal surrounding skin, before and after treatment in all patients. Before laser treatment the Pp-IX distribution demonstrated by LIF showed a demarcation between tumour and normal skin of about 15:1 for BCC and Bowen's disease, and 5:1 for T-cell lymphomas. Laser light from a pulsed frequency-doubled Nd:YAG laser pumping a dye laser with light emission at 630 nn was used for the therapy. The power density in the irradiation was kept below 110 mW/cm(2), in order to avoid hyperthermal effects. A total energy of 60 J/cm(2) was delivered for 10-20 min, depending on the tumour size. A complete response rate of 100% in superficial BCCs and 64% in nodular BCCs occurred after a single laser treatment, and a response rate of 100% was achieved after one additional. treatment in the nodular BCCs. in the Bowen's disease lesions a complete response of 90% was obtained with a single treatment. Two of the four T-cell lymphomas resolved completely. The follow-up time was between 6 and 14 months.
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| 7. |
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