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61.
Blood flow imaging with MR: spin-phase phenomena 总被引:2,自引:0,他引:2
Blood flow phenomena occurring when flow is within the magnetic resonance (MR) imaging plane were analyzed. In this situation, the signal intensity of vascular lumina is predominantly determined by spin-phase change phenomena, and section transition effects of moving spins can be neglected. In this paper, we develop the concepts of in-plane flow, with emphasis on the notion that the spatial variations in velocity and acceleration of blood, which mainly occur along vessel walls, are important determinants of intravascular signal loss in MR images. Flow patterns in the large mediastinal arteries were qualitatively and quantitatively analyzed in six healthy subjects and 14 patients with hemodynamic abnormalities using multiple electrocardiograph-gated image acquisition; ungated studies of 30 patients were analyzed for venous flow effects. Intraluminal signal was strongly dependent on the phase of the cardiac cycle and the echo number. Signal loss was found to occur along vessel walls, in vascular bends, and at bifurcations. 相似文献
62.
CF Samer Y Daali M Wagner G Hopfgartner CB Eap MC Rebsamen MF Rossier D Hochstrasser P Dayer JA Desmeules 《British journal of pharmacology》2010,160(4):919-930
Background and purpose:
Thrombus formation is commonly associated with pulmonary arterial hypertension (PAH). Thrombin may thus play an important role in the pathogenesis and pathophysiology of PAH. Hence, we investigated the contractile effects of thrombin and its mechanism in pulmonary artery.Experimental approach:
The cytosolic Ca2+ concentrations ([Ca2+]i), 20 kDa myosin light chain (MLC20) phosphorylation and tension development were evaluated using the isolated porcine pulmonary artery.Key results:
Thrombin induced a sustained contraction in endothelium-denuded strips obtained from different sites of a pulmonary artery, ranging from the main pulmonary artery to the intrapulmonary artery. In the presence of endothelium, thrombin induced a transient relaxation. The contractile effect of thrombin was abolished by either a protease inhibitor or a proteinase-activated receptor 1 (PAR1) antagonist, while it was mimicked by PAR1-activating peptide (PAR1AP), but not PAR4AP. The thrombin-induced contraction was associated with a small elevation of [Ca2+]i and an increase in MLC20 phosphorylation. Thrombin and PAR1AP induced a greater increase in tension for a given [Ca2+]i elevation than that obtained with high K+-depolarization. They also induced a contraction at a fixed Ca2+ concentration in α-toxin-permeabilized preparations.Conclusions and implications:
The present study revealed a unique property of the pulmonary artery. In contrast to normal arteries of the systemic circulation, thrombin induces a sustained contraction in the normal pulmonary artery, by activating PAR1 and thereby increasing the sensitivity of the myofilament to Ca2+. This responsiveness of the pulmonary artery to thrombin may therefore contribute to the pathogenesis and pathophysiology of PAH. 相似文献63.
In previous reports, duration of initial ventilation exceeding 1 month almost always predicts non-survival of babies with congenital myotonic dystrophy. However, a baby with this condition survived beyond infancy after 55 days' ventilation. We describe this case in detail, explain why the baby survived and highlight the importance of individualized assessment, in addition to applying general prognostic terms described in the literature. 相似文献
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67.
CB 《Best Practice Onkologie》2012,7(1):16
Die anthroposophische Misteltherapie kann etablierte onkologische Standardtherapien im Sinne einer umfassenderen und ganzheitlichen
Versorgung erg?nzen. 相似文献
68.
Cruz MT Gonçalo M Paiva A Morgado JM Figueiredo A Duarte CB Lopes MC 《Archives of dermatological research》2005,297(1):43-47
Chemokines are involved in the control of dendritic cell (DC) trafficking, which is critical for the immune response, namely
in allergic contact dermatitis (ACD). In this work, we investigated by flow cytometry the effect of the contact sensitizers
2,4-dinitrofluorobenzene (DNFB), 1,4-phenylenediamine (PPD) and nickel sulfate (NiSO4), on the surface expression of the chemokine receptors CCR6 and CXCR4 in DC. As an experimental model of a DC we used a fetal
skin-derived dendritic cell line (FSDC), which has morphological, phenotypical and functional characteristics of skin DC.
Our results show that all the skin sensitizers studied decreased the membrane expression of the chemokine receptors CCR6 and
CXCR4. In contrast, 2,4-dichloronitrobenzene (DCNB), the inactive analogue of DNFB without contact sensitizing properties,
was without effect on the surface expression of these receptors. Lipopolysaccharide (LPS), which induces the maturation of
DC, also reduced surface CCR6 and CXCR4 expression. 相似文献
69.
Stephen CB Teoh MBBS Eng-Yiat Yap FRCOphth Kah-Guan Au Eong RCS MMed 《Clinical & experimental ophthalmology》2001,29(4):213-216
Purpose : To report eight patients with diagnosed systemic lupus erythematosus (SLE) who presented with a variety of neuro‐ophthalmological complications and outcomes. Methods : A review of the follow up, subsequent management and outcomes of the neuro‐ophthalmological complications of eight patients with SLE. Results : The patients presented with a myriad of symptoms of varying severities. The most common manifestations were that of optic neuropathy and eye movement abnormalities. The outcome was variable ranging from complete recovery to optic atrophy with navigational visual acuity. Treatment was often empirical, although early treatment with corticosteroids has been tried with varying success. Conclusions : The pathophysiology in the neuro‐ ophthalmological manifestations of SLE is thought be due to vaso‐occlusive disease of the small vessels of the nerve and brain, secondary to an autoimmune process. Ophthalmologists may need to consider the diagnosis of SLE in young women who present with a recent onset of neuro‐ophthalmological symptoms and signs. 相似文献
70.
John J Ah-Chan BMedSc MBChB Gordon Sanderson BScFBOA Brendan JT Vote MBBS Anthony CB Molteno FRACO 《Clinical & experimental ophthalmology》2001,29(6):416-425
Aim : To determine what New Zealand ophthalmologists, general practitioners and optometrists consider important ophthalmic topic areas requiring emphasis in the medical undergraduate curriculum. Method : A total of 793 questionnaires related to the content and teaching of undergraduate ophthalmology were sent to ophthalmologists, general practitioners and optometrists. Results were analysed separately for the three respondent groups and as a whole. Results : Four hundred and fourteen questionnaires were returned (52% return rate). Overall responses of the three participant groups were similar and agreed favourably with the current curriculum. The ability to measure visual acuity (97%) and pupillary reflexes (93%), perform ophthalmoscopy (92%), and assess visual fields (68%) were regarded as ‘important or essential’ by the majority of respondents. Only 53% of respondents consider the ability to diagnose chronic open angle glaucoma as important. The respondents stressed the importance of the diagnosis of predominantly anterior segment disease contrasting with the traditional bias towards the teaching of ophthalmoscopy and posterior segment disease. The majority of respondents stressed the importance of graduating medical students being able to treat bacterial and allergic conjunctivitis, styes, blepharitis, corneal abrasion, and corneal and conjunctival foreign bodies, areas present but not normally emphasized in current curricula. Conclusion : The findings of this study provided additional data to facilitate curriculum design and illustrated the value of an integrated problem‐based learning approach in ophthalmology undergraduate teaching. 相似文献