| 41. |
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| 42. |
- Hellstrand, Sophie, et al.
(författare)
-
Dietary Data in the Malmö Offspring Study : Reproducibility, Method Comparison and Validation against Objective Biomarkers
- 2021
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Ingår i: Nutrients. - : MDPI AG. - 2072-6643. ; 13:5
-
Tidskriftsartikel (refereegranskat)abstract
- Irregular dietary intakes impairs estimations from food records. Biomarkers and method combinations can be used to improve estimates. Our aim was to examine reproducibility from two assessment methods, compare them, and validate intakes against objective biomarkers. We used the Malmö Offspring Study (55% women, 18-71 y) with data from a 4-day food record (4DFR) and a short food frequency questionnaire (SFFQ) to compare (1) repeated intakes (n = 180), (2) intakes from 4DFR and SFFQ (n = 1601), and (3) intakes of fatty fish, fruits and vegetables, and citrus with plasma biomarkers (n = 1433) (3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid [CMPF], β-carotene and proline betaine). We also combined 4DFR and SFFQ estimates using principal component analysis (PCA). Moderate correlations were seen between repeated intakes (4DFR median ρ = 0.41, SFFQ median ρ = 0.59) although lower for specific 4DFR-items, especially fatty/lean fish (ρ ≤ 0.08). Between-method correlations (median ρ = 0.33) were higher for intakes of overall food groups compared to specific foods. PCA scores for citrus (proline betaine ρ = 0.53) and fruits and vegetables (β-carotene: ρ = 0.39) showed the highest biomarker correlations, whereas fatty fish intake from the SFFQ per se showed the highest correlation with CMPF (ρ = 0.46). To conclude, the reproducibility of SFFQ data was superior to 4DFR data regarding irregularly consumed foods. Method combination could slightly improve fruit and vegetable estimates, whereas SFFQ data gave most valid fatty fish intake.
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| 43. |
- Himpens, B, et al.
(författare)
-
Free cytosolic calcium during spontaneous contractions in smooth muscle of the guinea-pig mesotubarium
- 1990
-
Ingår i: Pflügers Archiv. - 0031-6768. ; 417:4, s. 404-409
-
Tidskriftsartikel (refereegranskat)abstract
- The free intracellular calcium ion concentration ([Ca2+]i) was measured simultaneously with isometric force in strips of guinea-pig mesotubarium using the Fura-2 technique. During the relaxed period (5-15 min) between spontaneous contractions [Ca2+]i continues to decrease after full mechanical relaxation to reach a minimal level of 86 +/- 8 nM (n = 9) just before the start of the next contraction. During the spontaneous contractions (5-15 min) [Ca2+]i reached a maximum of 211 +/- 19 nM and then oscillated between 155 +/- 16 nM and 194 +/- 9 nM. Increased extracellular Ca2+ concentration to 10 mM from the standard concentration of 1.5 mM caused a decreased frequency of spontaneous contractions and an increase in [Ca2+]i both in the relaxed and contracted states. In 10 mM extracellular Ca2+, addition of AlF4-, as 1 mM NaF + 10 microM AlCl3, caused a sustained increase in [Ca2+]i and maintained force. Addition of verapamil (10 microM) in this situation decreased [Ca2+]i to the resting level. The results suggest that the cyclic appearance of trains of action potentials is related to variation in [Ca2+]i, possibly via inactivation of Ca2(+)-dependent K+ channels.
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| 44. |
- Lydrup, M L, et al.
(författare)
-
Effect of glibenclamide on membrane response to metabolic inhibition in smooth muscle of rat portal vein
- 1994
-
Ingår i: Journal of Vascular Research. - 1423-0135. ; 31:2, s. 82-91
-
Tidskriftsartikel (refereegranskat)abstract
- Vascular smooth muscle tone is dependent on oxidative metabolism, a phenomenon of potential importance for the metabolic regulation of blood flow to tissues. The response of the rat portal vein to inhibition of cell respiration by cyanide (0.1-1 mM) is a reduction of its spontaneous myogenic activity. The trains of action potentials triggering phasic contractions are reduced in duration, while the frequency of trains is often somewhat increased as the resting membrane potential in the intervals between spike trains is less negative by 6.5 mV. Glibenclamide (10(-7) M) did not affect the resting membrane potential or spontaneous mechanical activity of oxygenated portal veins, but partly restored the depressed myogenic activity in the presence of cyanide (0.5 mM). The spike trains were longer, while the membrane was depolarized by 3 mV compared with the effects of cyanide alone. Inhibition of both oxidative and glycolytic metabolism by 2 mM NaCN in a medium where glucose was replaced by beta-hydroxybutyrate caused a hyperpolarization which was abolished by 10(-7) M glibenclamide. The relaxing effect of the K+ channel opener cromakalim (5 x 10(-9) to 6.25 x 10(-7) M) was partly antagonized by glibenclamide. Basal cytosolic [Ca2+] was increased by cyanide, while the Ca2+ transients associated with phasic contractions were reduced in duration. This latter effect was partially reversed by glibenclamide. The effect of cyanide on high-K+ contractures, which are associated with sustained membrane depolarization and not dependent on repetitive spike activity, was not influenced by 10(-7) M glibenclamide. The effects of inhibited cell respiration on spontaneous electrical activity seem to reflect a depolarizing drive caused by inhibited active ion exchange mechanisms, modified by a repolarizing drive, possibly from ATP-regulated K+ channels, causing reduced duration of the spike trains. While glibenclamide affects spontaneous activity at all levels of oxidative blockade, glibenclamide-sensitive hyperpolarization is seen only when both oxidative and glycolytic metabolism is inhibited.
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| 45. |
- Lydrup, M L, et al.
(författare)
-
Effects of extracellular K+ and Ca2+ on membrane potential, contraction and 86Rb+ efflux in guinea-pig mesotubarium
- 1990
-
Ingår i: Pflügers Archiv. - 0031-6768. ; 415:6, s. 664-670
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of varying extracellular concentrations of K+ and Ca2+ [K+]o and [Ca2+]o on force development and membrane potential were investigated in the guinea-pig mesotubarium. At [K+]o up to 40 mM, spontaneous action potentials were present, while higher [K+]o gave sustained contractures at a stable membrane potential (-24 to -12 mV for [K+]o from 60 to 120 mM). Tension decreased successively with increasing [K+]o from 30 to 120 mM. The relaxing potency of the dihydropyridine Ca2+ antagonist, felodipine, increased as the membrane was depolarized with increasing [K+]o and action potentials ceased. These results are compatible with the existence of Ca2+ channels showing voltage-dependent affinity with dihydrophyridines. Increasing [Ca2+]o from 2.5 to 10 mM caused membrane hyperpolarization by about 11 mV and was accompanied by a lower frequency of spontaneous contractions and a longer duration of the relaxation between contractions. 86Rb+ efflux measurements in 60 mM K+ in the absence and presence of felodipine revealed a Ca2(+)-dependent component of the voltage-activated efflux. In normal solution (5.9 mM K+), efflux in the presence of felodipine was similar to the minimal value during normal spontaneous activity. The results indicate regulation of the permeability of K+ channels by the intracellular Ca2+ concentration ([Ca2+]i) and suggest participation of such channels in the generation of the regularly occurring bursts of action potentials characteristic of spontaneous activity in the mesotubarium.
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| 46. |
- Lydrup, M L, et al.
(författare)
-
Metabolic correlates to pacemaker activity in the smooth muscle of guinea-pig mesotubarium
- 1991
-
Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 141:2, s. 263-272
-
Tidskriftsartikel (refereegranskat)abstract
- Oxygen consumption (FO2) and lactate production (Flac) were measured during spontaneous activity in the guinea-pig mesotubarium. During spontaneous contractions FO2 increased to maximally 0.270 +/- 0.025 mumol min-1g-1 (n = 23), followed by a rapid fall immediately upon relaxation. In the relaxed period (5-15 min) between spontaneous contractions FO2 continued to slowly decrease by about 25% towards a final value of 0.150 +/- 0.01 mumol min-1g-1. Flac showed no consistent variation during the relaxed period. Ouabain (10(-6)M) produced a contracture, which was abolished by the Ca2(+)-antagonist felodipine (10(-6)M). In the presence of felodipine, addition of ouabain caused depolarization and a decrease of oxygen consumption by 21% and of lactate production by 31%. Exchange of glucose in the physiological Krebs solution for beta-hydroxybutyrate did not influence spontaneous activity, while subsequent addition of cyanide (2 mM) abolished contractions and caused a hyperpolarization of 15 mV. Blockade of ATP-dependent K+ channels by addition of glibenclamide (10(-7)M) to the relaxed muscle in this situation caused spontaneous contractile activity to reappear. In glucose-containing Krebs solution glibenclamide had no effect on the spontaneous contractile and electrical activity and contractions persisted after addition of cyanide. The relaxing and hyperpolarizing effect of pinacidil could be counteracted by addition of glibenclamide. The results suggest that a decrease in electrogenic Na+/K(+)-pump activity in the course of the relaxed period between contractions could contribute to the pacemaker behaviour. ATP-dependent K+ channels, while having little influence on the spontaneous contractile activity under normal metabolic conditions, could be activated during blockade of aerobic and anaerobic metabolism, leading to inhibition of pacemaker activity.
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| 47. |
- Lydrup, M L, et al.
(författare)
-
Paradoxical decrease in cytosolic calcium with increasing depolarization by potassium in guinea-pig mesotubarium smooth muscle
- 1992
-
Ingår i: Pflügers Archiv. - 0031-6768. ; 420:5-6, s. 428-433
-
Tidskriftsartikel (refereegranskat)abstract
- The free intracellular Ca2+ concentration ([Ca2+]i) was measured simultaneously with isometric force in strips of guinea-pig mesotubarium using the Fura-2 technique. [Ca2+]i and force were maximal at a relatively low (30 mM) concentration of extracellular K+ ([K+]o), and declined at 90 and 140 mM K+. Plateau values of both [Ca2+]i and force were higher in the presence of 5.10(-6) M ryanodine, indicating that the sarcoplasmic reticulum (SR) contributes to the decline with depolarization. Force and [Ca2+]i at 90 mM K+ were both lower then the high-K+ solution was applied after a period in 30 mM K+ than after a period in normal solution (5.9 mM K+), consistent with inactivation of Ca2+ channels during prolonged depolarization. Addition of carbachol to the depolarized muscle caused a maintained increase in force without maintained increase in [Ca2+]i. We conclude that the decrease in force at increased [K+]o (the "calcium-potassium paradox") is due to a membrane-potential-mediated decrease in [Ca2+]i and, to a lesser extent, to desensitization of the contractile-regulatory apparatus to Ca2+.
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| 48. |
- Lydrup, M L, et al.
(författare)
-
Rate of oxidative and glycolytic metabolism in the guinea-pig oviduct in relation to contractility and hormonal cycle
- 1986
-
Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 128:4, s. 525-533
-
Tidskriftsartikel (refereegranskat)abstract
- The rates of oxygen consumption and lactate production in the guinea-pig oviduct were measured together with registration of contractile activity during three phases of the hormonal cycle. In pro-oestrus (high oestrogen, low progesterone levels) and oestrus (time of ovulation, high oestrogen and progesterone) the rate of O2 consumption was higher than in dioestrus (low oestrogen, high progesterone). The frequency of spontaneous contractions was higher in oestrus than in the other phases. No significant differences in the proportion of the cross-sectional area occupied by smooth muscle were found between oviducts in di- and pro-oestrus. Stimulation by phenylephrine caused decreased frequency and increased amplitude of contractions in dioestrus but not in pro-oestrus, suggesting hormonal modulation of adrenergic mechanisms. The rate of relaxation of high-K+ contractures was higher in pro- than dioestrus. Lactate production and contents of ATP, ADP and phosphocreatine showed no significant variation with hormonal state. The increased rate of oxidative metabolism under oestrogenic dominance could in part reflect changes in ionic transport mechanisms, such as intracellular Ca2+ handling.
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| 49. |
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| 50. |
- Martner, Anna, 1979, et al.
(författare)
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Transient and durable T cell reactivity after COVID-19
- 2022
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 119:30
-
Tidskriftsartikel (refereegranskat)abstract
- This study analyzed whole blood samples (n = 56) retrieved from 30 patients at 1 to 21 (median 9) mo after verified COVID-19 to determine the polarity and duration of antigen-specific T cell reactivity against severe acute respiratory syndrome coronavirus 2-derived antigens. Multimeric peptides spanning the entire nucleocapsid protein triggered strikingly synchronous formation of interleukin (IL)-4, IL-12, IL-13, and IL-17 ex vivo until similar to 70 d after confirmed infection, whereafter this reactivity was no longer inducible. In contrast, levels of nucleocapsid-induced IL-2 and interferon-gamma remained stable and highly correlated at 3 to 21 mo after infection. Similar cytokine dynamics were observed in unvaccinated, convalescent patients using whole-blood samples stimulated with peptides spanning the N-terminal portion of the spike 1 protein. These results unravel two phases of T cell reactivity following natural COVID-19: an early, synchronous response indicating transient presence of multipolar, antigen-specific T helper (T-H) cells followed by an equally synchronous and durable T(H)1-like reactivity reflecting long-lasting T cell memory.
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