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Lenfeldt N, Andersson N, Agren-Wilsson A, Bergenheim AT, Koskinen LOD, Eklund A, Malm J. Cerebrospinal fluid pulse pressure method: a possible substitute for the examination of B waves. J Neurosurg 2005; 101:944-50. [PMID: 15597755 DOI: 10.3171/jns.2004.101.6.0944] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The appearance of numerous B waves during intracranial pressure (ICP) registration in patients with idiopathic adult hydrocephalus syndrome (IAHS) is considered to predict good outcome after shunt surgery. The aim of this study was to describe which physical parameters of the cerebrospinal fluid (CSF) system B-waves reflect and to find a method that could replace long-term B-wave analysis. METHODS Ten patients with IAHS were subjected to long-term registration of ICP and a lumbar constant-pressure infusion test. The B-wave presence, CSF outflow resistance (R(out)), and relative pulse pressure coefficient (RPPC) were assessed using computerized analysis. The RPPC was introduced as a parameter reflecting the joint effect of elastance and pulsatory volume changes on ICP and was determined by relating ICP pulse amplitudes to mean ICP. CONCLUSIONS The B-wave presence on ICP registration correlates strongly with RPPC (r = 0.91, p < 0.001, 10 patients) but not with CSF R(out). This correlation indicates that B waves-like RPPC-primarily reflect the ability of the CSF system to reallocate and store liquid rather than absorb it. The RPPC-assessing lumbar short-term CSF pulse pressure method could replace the intracranial long-term B-wave analysis.
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Andersson N, Alberius P, Örtegren J, Lindgren M, Bergström L. Photochromic mesostructured silica pigments dispersed in latex films. ACTA ACUST UNITED AC 2005. [DOI: 10.1039/b505319f] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chagin AS, Lindberg MK, Andersson N, Moverare S, Gustafsson JA, Sävendahl L, Ohlsson C. Estrogen receptor-beta inhibits skeletal growth and has the capacity to mediate growth plate fusion in female mice. J Bone Miner Res 2004; 19:72-7. [PMID: 14753739 DOI: 10.1359/jbmr.0301203] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED To determine the long-term role of ER beta in the regulation of longitudinal bone growth, appendicular and axial skeletal growth was followed and compared in female ER beta-/-, ER alpha-/-, and ER alpha-/- beta-/- mice. Our results show that ER beta inhibits appendicular and axial skeletal growth and has the capacity to induce fusion of the growth plates. INTRODUCTION Estrogen affects skeletal growth and promotes growth plate fusion in humans. In rodents, the growth plates do not fuse after sexual maturation, but prolonged treatment with supraphysiological levels of estradiol has the capacity to fuse the growth plates. It should be emphasized that the estrogen receptor (ER) alpha-/- and the ER alpha-/- beta-/-, but not the ER beta-/-, mouse models have clearly increased serum levels of estradiol. MATERIALS AND METHODS The skeletal growth was monitored by X-ray and dynamic histomorphometry, and the growth plates were analyzed by quantitative histology, calcein double labeling, bromodeoxyuridine (BrdU) incorporation, and TUNEL assay in 4- and 18-month-old female ER beta-/-, ER alpha-/-, and ER alpha-/- beta-/- mice. RESULTS Young adult (4-month-old) ER beta-/- mice demonstrated an increased axial- and appendicular-skeletal growth, supporting the notion that ER beta inhibits skeletal growth in young adult female mice. Interestingly, the growth plates were consistently fused in the appendicular skeleton of 18-month-old female ER alpha-/- mice. This fusion of growth plates, caused by a prolonged exposure to supraphysiological levels of estradiol in female ER alpha-/- mice, must be mediated through ER beta because old ER alpah-/- beta-/- mice displayed unchanged, unfused growth plates. CONCLUSIONS Our results confirm that ER beta is a physiological inhibitor of appendicular- and axial-skeletal growth in young adult female mice. Furthermore, we made the novel observation that ER beta, after prolonged supraphysiological estradiol exposure, has the capacity to mediate growth plate fusion in old female mice.
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Andersson N, Comer GL, Prix R. Are pulsar glitches triggered by a superfluid two-stream instability? PHYSICAL REVIEW LETTERS 2003; 90:091101. [PMID: 12689208 DOI: 10.1103/physrevlett.90.091101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Indexed: 05/24/2023]
Abstract
Mature neutron stars are expected to have several superfluid components. Strong evidence for this is provided by the glitches that have been observed in dozens of pulsars. We describe a superfluid analog of the two-stream instability that is well known in plasma physics and provide arguments that this instability is likely to be relevant for neutron stars. This is a new physical mechanism which may play a key role in explaining the glitch mechanism and which could also prove to be relevant in laboratory experiments on various superfluid systems.
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Andersson N, Grip H, Lindvall P, Koskinen LOD, Brändström H, Malm J, Eklund A. Air transport of patients with intracranial air: computer model of pressure effects. AVIATION, SPACE, AND ENVIRONMENTAL MEDICINE 2003; 74:138-44. [PMID: 12602445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
INTRODUCTION Air is commonly trapped within the skull in patients who have been treated for trauma or intracranial hemorrhage. In Sweden, when such a patient is transported by air ambulance it is standard procedure to maintain sea-level pressure in the cabin to prevent increased intracranial pressure (ICP). However, this type of flight operation is more difficult and expensive. Maintenance of sea-level cabin pressure is not common practice all over the world, and the criteria supporting the choice of pressurization during transport are inadequate and in need of evaluation. The purpose of this study was to develop and evaluate a model to simulate the influence of intracranial air on ICP during air transport. METHODS We identified an existing nonlinear model of the cerebral spinal fluid and intracranial pressure dynamics, then added intracranial air as a new component and evaluated the model through simulations. RESULTS The model behaved as expected, and the simulations indicated that under normal flying conditions with decreased cabin pressure the initial intracranial air volume will increase by approximately 30% at normal maximum cabin altitude, 8000 ft. The increase in ICP depends upon both the initial air volume and the rate of change in cabin altitude. For an intracranial air volume of 30 ml the estimated worst-case increments of ICP from sea level to maximum altitude would be from 10 mm Hg to 21.0 mm Hg, or from 20 mm Hg to 31.8 mm Hg. DISCUSSION Our results support the need for maintenance of sea-level pressure during air transport of patients with suspected intracranial air, since an ICP increment could potentially impair the patient's clinical condition.
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Andersson N, Surve VV, Lehto-Axtelius D, Ohlsson C, Håkanson R, Andersson K, Ryberg B. Drug-induced prevention of gastrectomy- and ovariectomy-induced osteopaenia in the young female rat. J Endocrinol 2002; 175:695-703. [PMID: 12475380 DOI: 10.1677/joe.0.1750695] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Both ovariectomy (Ovx) and gastrectomy (Gx) induce osteopaenia in rats and humans. While the effect of Ovx has been ascribed to oestrogen deficiency, the underlying mechanism behind Gx is poorly understood. Alendronate, oestrogen and parathyroid hormone (PTH) are known to prevent the osteopaenia induced by Ovx in rats. The purpose of the present study was to determine whether alendronate, oestrogen or PTH could also prevent Gx-evoked osteopaenia. Rats were Ovx-, Gx-, or were sham-operated (Sham) and were then treated with alendronate (50 micro g/kg/day), oestrogen (10 micro g/kg/day) or PTH(1-84) (75 micro g/kg/day) for eight weeks. At sacrifice, serum PTH was unaffected by surgery (Ovx, 64+/-8 pg/ml; Gx, 75+/-13 pg/ml; Sham, 58+/-11 pg/ml). The bone mineral density (BMD) of the fifth lumbar vertebra (L5) was analysed. Ovx and Gx reduced the BMD (ash weight/Volume) of the L5 by 15+/-4% and 22+/-3% respectively. Trabecular BMD and the cortical bone mineral content (BMC) of the femur were assessed using peripheral computed tomography. Both Ovx and Gx markedly reduced trabecular BMD in the metaphyseal area of the distal femur (Ovx, -37+/-7%; Gx, -49+/-7%). The cortical BMC of the femur was only slightly reduced. Alendronate prevented trabecular bone loss after both Ovx and Gx, while oestrogen and PTH prevented trabecular bone loss after Ovx but not after Gx. In conclusion, the bisphosphonate alendronate prevented both Ovx- and Gx-induced trabecular bone loss. In contrast, PTH and oestrogen prevented Ovx-induced but not Gx-induced trabecular bone loss, suggesting that the mechanism behind the trabecular bone loss in Ovx rats differs from that in Gx rats. The results support the notion that the mechanism of action for the bone-sparing effect of these drugs differs. The ability of alendronate, and probably also other bisphosphonates, to prevent Gx-evoked osteopaenia in the rat might be of potential clinical interest when dealing with post-Gx osteopaenia in humans.
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Lindberg MK, Weihua Z, Andersson N, Movérare S, Gao H, Vidal O, Erlandsson M, Windahl S, Andersson G, Lubahn DB, Carlsten H, Dahlman-Wright K, Gustafsson JA, Ohlsson C. Estrogen receptor specificity for the effects of estrogen in ovariectomized mice. J Endocrinol 2002; 174:167-78. [PMID: 12176656 DOI: 10.1677/joe.0.1740167] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Estrogen exerts a variety of important physiological effects, which have been suggested to be mediated via the two known estrogen receptors (ERs), alpha and beta. Three-month-old ovariectomized mice, lacking one or both of the two estrogen receptors, were given estrogen subcutaneously (2.3 micro g/mouse per day) and the effects on different estrogen-responsive parameters, including skeletal effects, were studied. We found that estrogen increased the cortical bone dimensions in both wild-type (WT) and double ER knockout (DERKO) mice. DNA microarray analysis was performed to characterize this effect on cortical bone and it identified four genes that were regulated by estrogen in both WT and DERKO mice. The effect of estrogen on cortical bone in DERKO mice might either be due to remaining ERalpha activity or represent an ERalpha/ERbeta-independent effect. Other effects of estrogen, such as increased trabecular bone mineral density, thymic atrophy, fat reduction and increased uterine weight, were mainly ERalpha mediated.
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Andersson N, Comer GL. Probing neutron-star superfluidity with gravitational-wave data. PHYSICAL REVIEW LETTERS 2001; 87:241101. [PMID: 11736491 DOI: 10.1103/physrevlett.87.241101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2001] [Indexed: 05/23/2023]
Abstract
We discuss the possibility that future gravitational-wave detectors may be able to detect various modes of oscillation of old, cold neutron stars. We argue that such detections would provide unique insights into the superfluid nature of neutron-star cores, and could also lead to a much improved understanding of pulsar glitches. Our estimates are based on a detector configuration with several narrow-band (cryogenic) interferometers operating as a "xylophone" which could lead to high sensitivity at high frequencies. We also draw on recent advances in our understanding of the dynamics of pulsating superfluid neutron-star cores.
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Surve VV, Andersson N, Alatalo S, Lehto-Axtelius D, Halleen J, Väänänen K, Håkanson R. Does combined gastrectomy and ovariectomy induce greater osteopenia in young female rats than gastrectomy alone? Calcif Tissue Int 2001; 69:274-80. [PMID: 11768197 DOI: 10.1007/s002230020044] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Osteopenia develops in experimental animals following surgical removal of the ovaries (ovariectomy. Ovx) or the stomach (gastrectomy, Gx). Though the effect of Ovx has been ascribed to estrogen deficiency, the mechanism behind the Gx-evoked osteopenia remains unknown. In order to compare Gx- and Ovx-evoked osteopenia, young female rats were subjected to Ovx, gx, the combination of ovx and Gx, or sham operation (SHAM). Serum osteoclast-derived tartrate-resistant acid phosphatase 5b was measured as an index of bone resorption, and serum osteocalcin as an index of bone formation/turnover. Bone resorption predominated over bone formation during the first 4 days after Ovx but not later. Bone resorption predominated over bone formation throughout the first 4-week period after Gx. the changes were not additive in the ovx+Gx group. Transillumination and histomorphometry of the calvariae revealed extensive osteopenia in the Gx and the Ovx+Gx groups but not in the Ovx group. Peripheral quantitative computerized tomography of the femur metaphysis showed a decrease in the trabecular bone mineral density (BMD) in all three groups although Ovx+Gx seemed to induce greater trabecular bone loss than Gx alone. However, dual energy X-ray absorptiometry (DXA) of the intact femurs revealed reduced bone mineral content (BMC) in the Gx and Ovx+Gx groups but not in the Ovx group. Indeed, cortical bone was impaired by Gx and Ovx+Gx but not by Ovx. Hence, it seems clear that the Gx-evoked osteopenia differs from that induced by Ovx but that the osteopenia induced by Ovx+Gx is only marginally greater than that induced by Gx alone.
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Surve VV, Andersson N, Lehto-Axtelius D, Håkanson R. Comparison of osteopenia after gastrectomy, ovariectomy and prednisolone treatment in the young female rat. ACTA ORTHOPAEDICA SCANDINAVICA 2001; 72:525-32. [PMID: 11728082 DOI: 10.1080/000164701753532880] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Rat models of osteopenia include ovariectomy and long-term glucocorticoid treatment. Although ovariectomy produces significant trabecular bone loss after 2 weeks, long-term glucocorticoid treatment has been reported to cause osteopenia in some studies but not in others. In the present 8-week-study, we compared the osteopenia associated with gastrectomy (GX) to that induced by ovariectomy (OVX) or prednisolone (PRE) treatment. Female Sprague-Dawley rats (10 weeks old) were subjected to GX, OVX, PRE treatment or SHAM operation. At the end of the study, calvariae, femurs and fifth lumbar vertebrae (L5) were collected and subjected to bone density measurement (femur and L5), transillumination (calvaria) and histomorphometry (calvaria and femur). Bone density was reduced in L5 and the distal femur in the OVX and GX groups, but not in the PRE group. Transillumination of the calvaria showed marked bone loss in the GX rats, but not in the other groups. Morphometric analysis of the femur revealed reduced trabecular bone volume, trabecular thickness, trabecular number and osteoclast number, but increased osteoclast surface (expressed as per cent of the trabecular bone surface covered by osteoclasts) in the GX and OVX rats. The PRE rats seemed unaffected. Cortical thickness was reduced in the GX rats, but not in the other groups. The findings indicate that GX induces osteopenia in, e.g., femur and vertebra of a magnitude similar to or greater than that induced by OVX, while at the same time inducing osteopenia in the calvaria. Although osteoclast activation seems to contribute, the precise mechanism underlying the GX-evoked osteopenia remains obscure.
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Andersson N, Lindberg MK, Ohlsson C, Andersson K, Ryberg B. Repeated in vivo determinations of bone mineral density during parathyroid hormone treatment in ovariectomized mice. J Endocrinol 2001; 170:529-37. [PMID: 11524233 DOI: 10.1677/joe.0.1700529] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The recent development of different genetically modified mice with potentially interesting bone phenotypes has increased the demand for effective non-invasive methods to evaluate effects on bone of mice during growth and development, and for drug evaluation. In the present study, the skeleton was analyzed by repeated in vivo scans using dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Ovariectomized (ovx) mice treated with parathyroid hormone (PTH) were used as an animal model to evaluate these two techniques at different times after the onset of treatment. Female mice (6 weeks of age) were allocated randomly to four groups: (1) sham-operated+vehicle; (2) ovx+vehicle; (3) sham-operated+PTH(1-84) 150 microg/kg per day; (4) ovx+PTH. Six weeks after ovariectomy the drug treatment began and was continued for 8 weeks. The total body bone mineral content (BMC) and total body areal bone mineral density (BMD) were measured by DXA. Ovariectomy reduced total body BMC and total body areal BMD by 6.2+/-1.7% and 2.6+/-0.9% respectively. No effect of PTH on total body BMC was seen during the treatment period. The trabecular volumetric BMD was measured by pQCT. Ovariectomy reduced the trabecular volumetric BMD by 52+/-6.7%. The pQCT technique detected a clear effect on trabecular volumetric BMD after 2 weeks of PTH treatment (ovx 94+/-29% and sham-operated 46+/-10% more than vehicle-treated). The cortical bone was measured in a mid-diaphyseal pQCT scan of the tibia. Ovariectomy reduced the cortical BMC by 9+/-2%. PTH treatment for 8 weeks increased cortical BMC in ovx mice. In conclusion, the pQCT technique is more sensitive than the DXA technique in the detection of bone loss after ovariectomy and increased bone mass after PTH treatment in mice. Notably, the pQCT, but not the DXA, technique detected a dramatic effect as early as after 2 weeks of PTH treatment. Dynamic pQCT measurements will be useful for monitoring skeletal changes during growth and development, and for drug evaluation in mice.
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Andersson N, Källén A, Thorsson L. A randomized controlled assessment of the effects of different dosing regimens of budesonide on the HPA-axis in healthy subjects. Br J Clin Pharmacol 2001; 51:325-8. [PMID: 11318767 PMCID: PMC2014452 DOI: 10.1046/j.1365-2125.2001.01353.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To investigate the effect on the hypothalamo-pituitary-adrenal (HPA) axis of treatment with budesonide, 400 microg once daily, morning or evening, or 200 microg twice daily, and 800 microg twice daily via Turbuhaler in a randomized, placebo-controlled, double-blind, double-dummy crossover study. METHODS Healthy men received budesonide, 400 microg in the morning (08.00-09.00 h) or evening (20.00-21.00 h), budesonide, 200 microg twice daily, 800 microg twice daily, and placebo twice daily, for 1 week each. Plasma and urine samples were obtained over 24 h on day 7 for cortisol determination. Twenty-five subjects completed all treatments, and 27 were included in the analysis. RESULTS The 24 h plasma cortisol concentrations vs placebo (95% CI) were 98% (89, 108) for 400 microg in the morning, 92% (83, 100) for 400 microg in the evening, 95% (86, 104) for 200 microg twice daily, and 76% (70, 84) for 800 microg twice daily. CONCLUSIONS Budesonide at a dose of 400 microg day-1 via Turbuhaler had no statistically significant effect on 24 h cortisol production, irrespective of whether treatment is given once or twice daily, whereas a dose of 800 microg twice daily resulted in a statistically significant suppression vs placebo. Neither could a significant difference be found between morning and evening dosing.
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Eklund A, Agren-Wilsson A, Andersson N, Bergenheim AT, Koskinen LO, Malm J. Two computerized methods used to analyze intracranial pressure B waves: comparison with traditional visual interpretation. J Neurosurg 2001; 94:392-6. [PMID: 11235941 DOI: 10.3171/jns.2001.94.3.0392] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Slow and rhythmic oscillations in intracranial pressure (ICP), also known as B waves, have been claimed to be one of the best preoperative predictive factors in idiopathic adult hydrocephalus syndrome (IAHS). Definitions of B waves vary widely, and previously reported results must be treated with caution. The aims of the present study were to develop a definition of B waves, to develop a method to estimate the B-wave content in an ICP recording by using computer algorithms, and to validate these procedures by comparison with the traditional visual interpretation. METHODS In eight patients with IAHS, ICP was continuously monitored for approximately 20 hours. The ICP B-wave activity as a percentage of total monitoring time (B%) was estimated by using visual estimation according to the definition given by Lundberg, and also by using two computer algorithms (Methods I and II). In Method I each individual wave was classified as a B wave or not, whereas Method II was used to estimate the B-wave content by evaluating the B-wave power in 10-minute blocks of ICP recordings. CONCLUSIONS The two computerized algorithms produced similar results. However, with the amplitude set to 1 mm Hg, Method I yielded the highest correlation with the visual analysis (r = 0.74). At least 5 hours of monitoring time was needed for an acceptable approximation of the B% in an overnight ICP recording. The advantages of using modern technology in the analysis of B-wave content of ICP are obvious and these methods should be used in future studies.
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Andersson N, Glampedakis K. Superradiance resonance cavity outside rapidly rotating black holes. PHYSICAL REVIEW LETTERS 2000; 84:4537-4540. [PMID: 10990734 DOI: 10.1103/physrevlett.84.4537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/1999] [Revised: 03/14/2000] [Indexed: 05/23/2023]
Abstract
We discuss the late-time behavior of a dynamically perturbed Kerr black hole. We present analytic results for near-extreme Kerr black holes that show that the large number of virtually undamped quasinormal modes that exist for nonzero values of the azimuthal eigenvalue m combine in such a way that the field oscillates with an amplitude that decays as 1/t at late times. This prediction is verified using numerical time evolutions of the Teukolsky equation. We argue that the observed behavior can be understood in terms of the presence of a "superradiance resonance cavity" immediately outside the black hole, and discuss whether it may be relevant for astrophysical black holes.
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Andersson N, Jones DI, Kokkotas KD, Stergioulas N. r-Mode Runaway and Rapidly Rotating Neutron Stars. THE ASTROPHYSICAL JOURNAL 2000; 534:L75-L78. [PMID: 10790075 DOI: 10.1086/312643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2000] [Accepted: 03/10/2000] [Indexed: 05/23/2023]
Abstract
We present a simple spin-evolution model that predicts that rapidly rotating accreting neutron stars will be confined mainly to a narrow range of spin frequencies: P=1.5-5 ms. This is in agreement with current observations of neutron stars in both the low-mass X-ray binaries and the millisecond radio pulsars. The main ingredients in the model are (1) the instability of r-modes above a critical spin rate, (2) the thermal runaway that is due to the heat released as viscous damping mechanisms counteract the r-mode growth, and (3) a revised estimate of the strength of the dissipation that is due to the presence of a viscous boundary layer at the base of the crust in an old and relatively cold neutron star. We discuss the gravitational waves that are radiated during the brief r-mode-driven spin-down phase. We also briefly touch on how the new estimates affect the predicted initial spin periods of hot young neutron stars.
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Andersson N, Rhedin M, Peteri-Brunbäck B, Andersson K, Cabero JL. Gastrin effects on isolated rat enterochromaffin-like cells following long-term hypergastrinaemia in vivo. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1451:297-304. [PMID: 10556584 DOI: 10.1016/s0167-4889(99)00101-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The enterochromaffin-like (ECL) cells play an important role in the regulation of gastric acid secretion. They respond to gastrin by a prompt increase in histamine secretion, an effect which is mediated by the CCK-(B)/gastrin receptor acting through the IP(3)/DAG pathway. In the rat, long-term treatment with acid secretion inhibitors induces hypergastrinaemia which, in turn, results in ECL cell hypertrophy and hyperplasia. The aim of the present study was to evaluate various functional parameters in acutely isolated rat ECL cells, following long-term hypergastrinaemia in vivo. Rats were treated with vehicle or a supramaximal daily dose of omeprazole for more than 10 weeks to ensure ECL cell hyperplasia. ECL cells were isolated from vehicle-treated animals and 24, 72 and 120 h after the last dose of omeprazole. The functional activity of the acutely isolated ECL cells was determined by measuring gastrin-and forskolin-induced histamine secretion. Changes in cytosolic free calcium upon gastrin stimulation were monitored by digital video imaging. ECL cells successively regained their ability to respond to gastrin following long-term hypergastrinaemia, reaching close to vehicle-treated levels 120 h after the last dose of omeprazole. In the rat, the response pattern of the ECL cells appears to normalise in parallel with the normalisation of plasma gastrin levels.
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Boorsma M, Andersson N, Larsson P, Ullman A. Assessment of the Relative Systemic Potency of Inhaled Fluticasone and Budesonide. Chest 1997. [DOI: 10.1016/s0012-3692(15)53055-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kidney JC, Boulet LP, Hargreave FE, Deschesnes F, Swystun VA, O'Byrne PM, Choudry N, Morris MM, Jennings B, Andersson N, Andreasson A, Cockcroft DW. Evaluation of single-dose inhaled corticosteroid activity with an allergen challenge model. J Allergy Clin Immunol 1997; 100:65-70. [PMID: 9257789 DOI: 10.1016/s0091-6749(97)70196-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Inhaled corticosteroids are the most commonly used antiinflammatory agents for asthma. There is no simple way to compare objectively the relative potency of inhaled corticosteroids. The allergen-induced late asthmatic response (LAR) can be suppressed by a single dose of inhaled corticosteroid. OBJECTIVE This study was undertaken to evaluate LAR as a model for the determination of the relative potency of single doses of inhaled corticosteroids. METHODS We compared doses of 200 and 800 microg of a highly active inhaled corticosteroid (budesonide) with placebo and a marginally active investigational inhaled corticosteroid (D5159). Ten atopic patients with asthma completed a randomized, double-blind, double-dummy, multicenter, four-way, crossover trial. A standardized allergen challenge with the identical dose of allergen was performed 10 minutes after each of four blinded, single-dose treatments: 200 microg of budesonide, 800 microg of budesonide, 8 mg of D5159, and placebo, all administered from Turbuhaler. The LAR was recorded as the maximum percent fall in FEV1 between 4 and 7 hours, and the allergen-induced increase in methacholine airway responsiveness at 24 hours was recorded as the A log PC20 from the day before to the day after allergen challenge. RESULTS There were no significant differences in the early asthmatic responses during the 4 days; the mean maximum percent in FEV1 fall ranged between 19.5% and 22%. D5159 produced a slight inhibition of the LAR with maximum percent fall in FEV1 recorded as 28.8% +/- 5.0% for D5159 versus 34.1% +/- 4.8% for placebo (p < 0.05). There was a greater reduction recorded after administration of the two doses of budesonide. The mean LAR was 15.1% +/- 3.8% for 200 microg of budesonide and 11.2% +/- 2.3% for 800 microg of budesonide (p < 0.01 compared with placebo and D5159). The two doses of budesonide were not statistically different. Airway responsiveness to methacholine increased by 1.07 doubling doses 24 hours after allergen challenge. This increased airway responsiveness was slightly, but not significantly, reduced by the three active treatments (0.6 to 0.91 doubling doses). CONCLUSION The allergen-induced LAR model was able to differentiate a single dose of an active inhaled corticosteroid from placebo and a highly potent inhaled corticosteroid from a weak inhaled corticosteroid. The model did not differentiate between 2 fourfold doses of the highly active inhaled corticosteroid (at the doses used in this study), neither for the fall in FEV1 nor for the increase in airway hyperresponsiveness.
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Andersson N, Onozawa H. Quasinormal modes of nearly extreme Reissner-Nordström black holes. Int J Clin Exp Med 1996; 54:7470-7475. [PMID: 10020762 DOI: 10.1103/physrevd.54.7470] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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70
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Andersson N, Kokkotas KD. Gravitational Waves and Pulsating Stars: What Can We Learn from Future Observations? PHYSICAL REVIEW LETTERS 1996; 77:4134-4137. [PMID: 10062457 DOI: 10.1103/physrevlett.77.4134] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
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71
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Boorsma M, Andersson N, Larsson P, Ullman A. Assessment of the relative systemic potency of inhaled fluticasone and budesonide. Eur Respir J 1996; 9:1427-32. [PMID: 8836654 DOI: 10.1183/09031936.96.09071427] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Studies using dry powder devices have suggested that fluticasone propionate (FP) has a greater systemic effect than budesonide (BUD). The aim of the present study was to investigate and compare the relative systemic potency of FP and BUD from their respective pressurized metered-dose inhalers (pMDIs). A placebo-controlled, open, randomized, cross-over study was conducted in 21 healthy male volunteers. Placebo, BUD (200, 400 and 1,000 micrograms b.i.d.) and FP (200, 375 and 1,000 micrograms b.i.d.) were inhaled for 4 days, with a wash-out period of at least 3 days between treatments. Blood samples for cortisol analysis were drawn during the last 24 h of each treatment period. Cortisol levels, measured as 24 h pooled plasma cortisol, were statistically significantly lower (p = 0.0001) for all dose levels during FP pMDI treatment (21, 39 and 84% suppression from placebo) than during BUD pMDI treatment (1, 3 and 27% suppression from placebo). The relative systemic potency FP:BUD was 3.7:1 (95% confidence interval (95% CI) 2.9-4.8)). The relative systemic potency based on the single 08:00 h samples was 5.2:1 (95% CI 3.0-9.3). In conclusion, in healthy male volunteers using pressurized metered-dose inhalers, fluticasone propionate was shown to have a stronger systemic effect than budesonide.
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Nummela A, Andersson N, Häkkinen K, Rusko H. Effect of inclination on the results of the maximal anaerobic running test. Int J Sports Med 1996; 17 Suppl 2:S103-8. [PMID: 8844273 DOI: 10.1055/s-2007-972909] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study investigated the effect of treadmill inclination on the maximal anaerobic running test (MART). Ten male subjects ran a 20-m speed test on a track to determine the maximal running velocity (V20m) and performed three MARTs at the grades of 1 degree, 4 degrees and 7 degrees in a random order. Each MART included n 20-s sprints at gradually increased velocity and counter-movement jumps (CMJ) which were performed before and after the exhausting sprints. At each grade, the power (oxygen demand) of the sprints was determined by extrapolating the individual steady state oxygen uptake of three submaximal running velocities measured separately at the corresponding grades. Maximal power (Pmax), power at 10mM (P10mM) and 5 mM (P5mM) blood lactate levels as well as peak blood lactate concentration (peak BLa) were determined at each MART. The Pmax increased from 94.1 +/- 8.8 and 110.0 +/- 10.2 to 119.5 +/- 8.0 ml.kg-1.min-1 when the treadmill inclination increased from 1 degree and 4 degrees to 7 degrees, respectively (p < 0.001). P10mM and P5mM also increased with the inclination (p < 0.001). Correlation coefficients of the Pmax with CMJrest and V20m were 0.77 and 0.69 at the grade of 1 degree, 0.75 and 0.59 at the grade of 4 degrees, and 0.62 and 0.42 at the grade of 7 degrees, respectively. The increased peak BLa (p < 0.01) with the treadmill inclination suggests that lactic capacity was not completely used at the grades of 1 degree and 4 degrees. In conclusion, the maximal power increased with the grade of uphill running in the MART. Furthermore, the present results suggest that the importance of force and velocity components of the neuromuscular system decreased and the importance of metabolic component increased with the increased grade of the uphill running.
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Andersson N, da Sousa CP, Paredes S. Social cost of land mines in four countries: Afghanistan, Bosnia, Cambodia, and Mozambique. BMJ (CLINICAL RESEARCH ED.) 1995; 311:718-21. [PMID: 7549685 PMCID: PMC2550718 DOI: 10.1136/bmj.311.7007.718] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVES To document the effects of land mines on the health and social conditions of communities in four affected countries. DESIGN A cross design of cluster survey and rapid appraisal methods including a household questionnaire and qualitative data from key informants, institutional reviews, and focus groups of survivors of land mines from the same communities. SETTING 206 communities, 37 in Afghanistan, 66 in Bosnia, 38 in Cambodia, and 65 in Mozambique. SUBJECTS 174,489 people living in 32,904 households in the selected communities. MAIN OUTCOME MEASURES Effects of land mines on food security, residence, livestock, and land use; risk factors: extent of individual land mine injuries; physical, psychological, social, and economic costs of injuries during medical care and rehabilitation. RESULTS Between 25% and 87% of households had daily activities affected by land mines. Based on expected production without the mines, agricultural production could increase by 88-200% in different regions of Afghanistan, 11% in Bosnia, 135% in Cambodia, and 3.6% in Mozambique. A total of 54,554 animals was lost because of land mines, with a minimum cash value of $6.5m, or nearly $200 per household. Overall, 6% of households (1964) reported a land mine victim; a third of victims died in the blast. One in 10 of the victims was a child. The most frequent activities associated with land mine incidents were agricultural or pastoral, except in Bosnia where more than half resulted from military activities, usually during patrols. Incidences have more than doubled between 1980-3 and 1990-3, excluding the incidents in Bosnia. Some 22% of victims (455/2100) were from households reporting attempts to remove land mines; in these households there was a greatly increased risk of injury (odds ratio 4.2 and risk difference 19% across the four countries). Lethality of the mines varied; in Bosnia each blast killed an average of 0.54 people and injured 1.4, whereas in Mozambique each blast killed 1.45 people and wounded 1.27. Households with a land mine victim were 40% more likely to experience difficulty in providing food for the family. Family relationships were affected for around one in every four victims and relationships with colleagues in 40%. CONCLUSIONS Land mines seriously undermine the economy and food security in affected countries; they kill and maim civilians at an increasing rate. The expense of medical care and rehabilitation add economic disability to the physical burden. Awareness of land mines can be targeted at high risk attitudes, such as those associated with tampering with mines.
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Andersson N. Scattering of massless scalar waves by a Schwarzschild black hole: A phase-integral study. PHYSICAL REVIEW. D, PARTICLES AND FIELDS 1995; 52:1808-1820. [PMID: 10019407 DOI: 10.1103/physrevd.52.1808] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Andersson N, Nummela A, Häkkinen K, Rusko HK. EFFECT OF TREADMILL SLOPE ON MAXIMAL ANAEROBIC RUNNING POWER TEST. Med Sci Sports Exerc 1995. [DOI: 10.1249/00005768-199505001-00091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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