| 1. |
- Crenshaw, D. M., et al.
(författare)
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Multiwavelength observations of short-timescale variability in NGC 4151. I. Ultraviolet observations
- 1996
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 322-335335
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Tidskriftsartikel (refereegranskat)abstract
- Presents the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short-timescale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed continuously with the International Ultraviolet Explorer for 9.3 days, yielding a pair of LWP and SWP spectra every ~70 minutes, and during 4 hr periods for 4 days prior to and 5 days after the continuous-monitoring period. The sampling frequency of the observations is an order of magnitude higher than that of any previous UV monitoring campaign on a Seyfert galaxy. The continuum fluxes in bands from 1275 to 2688 Aring went through four significant and well-defined ldquoeventsrdquo of duration 2-3 days during the continuous-monitoring period. The authors find that the amplitudes of the continuum variations decrease with increasing wavelength, which extends a general trend for this and other Seyfert galaxies to smaller timescales (i.e., a few days). The continuum variations in all the UV bands are simultaneous to within an accuracy of ~0.15 days, providing a strict constraint on continuum models. The emission-line light curves show only one major event during the continuous monitoring (a slow rise followed by a shallow dip) and do not correlate well with continuum light curves over the short duration of the campaign, because the timescale for continuum variations is apparently smaller than the response times of the emission lines
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| 2. |
- Jiang, Z. K, et al.
(författare)
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Lifetimes of Rydberg Levels In the Perturbed 6snp P-1,3(1) Series of Ybi
- 1995
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Ingår i: Physics Letters. Section A: General, Atomic and Solid State Physics. - : Elsevier BV. - 0375-9601. ; 204:1, s. 49-53
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Tidskriftsartikel (refereegranskat)abstract
- Using two methods: (1) three-step excitation and (2) single UV photon excitation in an atomic beam with direct observation of the decay of the fluorescence light, we have measured the lifetimes of the Rydberg levels of YbI belonging to the perturbed series 6snp J = 1 levels. The measured values have been interpreted by the multichannel quantum defect theory (MQDT).
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| 3. |
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| 4. |
- Eriksson, Jan W, 1959, et al.
(författare)
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Successful treatment with plasmapheresis, cyclophosphamide, and cyclosporin A in type B syndrome of insulin resistance. Case report.
- 1998
-
Ingår i: Diabetes care. - 0149-5992 .- 1935-5548. ; 21:8, s. 1217-20
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Tidskriftsartikel (refereegranskat)abstract
- CASE HISTORY: A woman born in 1949 was diagnosed in 1990 with systemic lupus erythematosus. She was treated with prednisolone, and < 1 year later she presented with marked hyperglycemia. Large doses of insulin were given four times per day. Even though the patient was thin (BMI 17.4 kg/m2), very little improvement was seen. INVESTIGATIONS AND TREATMENT: Serum insulin levels were high, and a euglycemic clamp investigation confirmed severe insulin resistance. The patient's serum contained insulin receptor antibodies inhibiting insulin binding, and thus the patient had a type B syndrome of insulin resistance. After diet and exercise, glycemic control stabilized and insulin treatment was withdrawn. However, in late 1993 she was in a catabolic and hyperglycemic state even though prednisolone doses were increased and azathioprin was added. In early 1994 she was treated with plasmapheresis and cyclophosphamide i.v. Subsequently, cyclosporin A was started as a maintenance therapy in addition to azathioprin. There was a rapid and sustained clinical improvement. Since late 1994 and onward, there is no sign of diabetes or glucose intolerance and there are no demonstrable insulin receptor antibodies in the patient's serum. DISCUSSION: Severe type B insulin resistance may respond favorably to treatment with plasmapheresis and cyclophosphamide followed by cyclosporin A in combination with azathioprin.
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| 5. |
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| 6. |
- Rudolph, Dirk, et al.
(författare)
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Rotational Bands in the Doubly Magic Nucleus 56Ni
- 1999
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Ingår i: Physical Review Letters. - 1079-7114. ; 82:19, s. 3763-3766
-
Tidskriftsartikel (refereegranskat)abstract
- Structures of the medium- to high-spin states in the doubly magic nucleus Ni-56 have been investigated using the reaction Si-28(Ar-36, 2 alpha) and the gamma-ray spectrometer Gammasphere in conjunction with the 4 pi charged-particle detector array Microball. Two well-deformed rotational bands have been identified. There is evidence that one of the bands, which is identical to a sequence in the odd-odd neighbor Cu-58, partially decays via proton emission into the ground state of Co-55. Predictions of extensive large-scale shell-model and cranked Hartree-Fock and Hartree-Fock-Bogolyubov calculations are compared with the experimental data.
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| 7. |
- Yu, Z W, et al.
(författare)
-
Cryptic receptors for insulin-like growth factor II in the plasma membrane of rat adipocytes : a possible link to cellular insulin resistance
- 1996
-
Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1282:1, s. 57-62
-
Tidskriftsartikel (refereegranskat)abstract
- To further elucidate the mechanisms for short-term regulation of the receptor for insulin-like growth factor II (IGF-II), we investigated effects of insulin, cAMP and phosphatase inhibitors on cell surface 125I-IGF-II binding in rat adipocytes. Preincubation with the serine/threonine phosphatase inhibitor okadaic acid (OA, 1 microM) or the non-hydrolysable cAMP analogue N6-mbcAMP (4 mM) markedly impaired insulin-stimulated 125I-IGF-II binding. Furthermore, addition of OA enhanced the inhibitory effect exerted by N6-mbcAMP. N6-mbcAMP also induced an insensitivity to insulin which was normalized by concomitant addition of the tyrosine phosphatase inhibitor vanadate (0.5 mM). In contrast, vanadate did not affect the impairment in maximal insulin-stimulated 125I-IGF-II binding produced by either OA or N6-mbcAMP. Phospholipase C (PLC), which cleaves phospholipids at the cell surface, markedly enhanced cell surface 125I-IGF-II binding in a concentration-dependent manner. Scatchard analysis demonstrated that the effect of PLC was due to an increased number of binding sites suggesting that "cryptic' IGF-II receptors are associated with the plasma membrane (PM). PLC (5 U/ml) also reversed the N6-mbcAMP-induced decrease of 125I-IGF-II binding at a low insulin concentration (10 microU/ml). Taken together, these data indicate that cAMP, similar to its effects on the glucose transporter GLUT 4 and the insulin receptor, may increase the proportion of functionally cryptic IGF-II receptors in the PM through mechanisms involving serine phosphorylation, possibly of a docking or coupling protein. Tyrosine phosphorylation appears to exert an opposite effect promoting the full cell surface expression of receptors.
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| 8. |
- Yu, Z W, et al.
(författare)
-
Effects of peroxovanadate and vanadate on insulin binding, degradation and sensitivity in rat adipocytes
- 1996
-
Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1310:1, s. 103-109
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of vanadate and the stable peroxovanadate compound bpV(pic) on insulin binding and degradation were investigated in rat adipocytes under conditions of ongoing receptor cycling. Both bpV(pic) and vanadate increased 125I-insulin binding to intact cells through an increase in apparent receptor affinity. The maximal effect of bpV(pic) was to increase binding approximately 4-fold (EC50 0.06 +/- 0.01 mM), whereas vanadate increased binding approximately 2-fold (EC50 1.4 +/- 0.2 mM). Removal of cell surface insulin-receptor complexes with trypsin showed that the effects on binding exerted by bpV(pic) and vanadate were due to a similar increase in both cell surface binding and intracellular accumulation of radioactivity. Both bpV(pic) and vanadate inhibited the degradation of 125I-insulin in medium containing 1% bovine serum albumin. The ratio of degraded/intact intracellular 125I-insulin was also markedly reduced by these agents, suggesting that they inhibit intracellular insulin-degrading proteases. Similar to previous findings with vanadate, bpV(pic) stimulated glucose transport and, at low concentrations, enhanced insulin sensitivity. Taken together, these data demonstrate that both bpV(pic) and vanadate inhibit insulin degradation. In addition, they significantly enhance cell surface insulin binding in rat fat cells and this is associated with an improved insulin sensitivity.
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| 9. |
- Yu, Z W, et al.
(författare)
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Peroxovanadate and insulin action in adipocytes from NIDDM patients. Evidence against a primary defect in tyrosine phosphorylation
- 1997
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 40:10, s. 1197-1203
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the effects of insulin and the stable peroxovanadate compound potassium bisperoxopicolinatooxovanadate (bpV(pic)), a potent inhibitor of phosphotyrosine phosphatases, on lipolysis and glucose uptake in subcutaneous adipocytes from 10 male patients with non-insulin-dependent diabetes mellitus (NIDDM) and 10 matched non-diabetic control subjects. Lipolysis stimulated by isoprenaline or the cAMP analogue, 8-bromo-cyclic AMP (8-br-cAMP), was reduced by approximately 40 % in NIDDM compared to control subjects. In both groups bpV(pic) exerted an antilipolytic effect that was similar to insulin (∼ 50 % inhibition). 14C-U-glucose uptake was dose-dependently increased by bpV(pic) treatment, but this effect and also that of insulin were impaired in NIDDM compared to control (bpV(pic) 1.6-fold vs 2.4-fold and insulin 2.2-fold vs 3.4-fold). Furthermore, low concentrations of bpV(pic) did not affect insulin-stimulated glucose uptake, although tyrosine phosphorylation of the insulin receptor β-subunit was clearly increased by bpV(pic). In conclusion, 1) β-adrenergic stimulation of lipolysis in vitro is attenuated in NIDDM adipocytes due to post-receptor mechanisms. 2) Both insulin and bpV(pic) decrease lipolysis and enhance glucose uptake in control as well as NIDDM adipocytes. The effect on glucose uptake, but not that on lipolysis, is impaired in NIDDM cells. 3) Peroxovanadate does not improve sensitivity and responsiveness to insulin in NIDDM adipocytes, showing that insulin-resistant glucose uptake in NIDDM is not overcome by phosphotyrosine-phosphatase inhibition and, thus, probably is not caused by impaired tyrosine phosphorylation events alone.
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| 10. |
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