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Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
4.
目的评估十二指肠-空肠导管(Endoluminal Duodeno-Jejunal Tube,EDJT)在活体猪实验动物模型中减缓体重增加的可行性,及其在中短期生存中的安全性。方法本项研究共用8只45kg重的Yorkshire猪,其中3只置入180emEDJT,1只置入360cm EDJT,另4只猪作为对照组。切开十二指肠,将EDJT导管缝合固定在十二指肠近Vater壶腹起始处。结果评估全部猪的不适反应和体重,每日一次,共7周,未发现严重并发症发生。术后7周3组动物的平均体重变化百分率:对照组、180cm组和360cm组分别是22.5%,6%和-2.8%。EDJT组(180cm组、360cm组)体重增加明显减慢,与对照组相比,有统计学意义(P=0.05)。结论EDJT可以安全使用,无肠梗阻、肠套叠或胰腺炎等并发症发生。EDJT可明显减缓体重增加。 相似文献
5.
Maxillary sinusitis in adults: an evaluation of placebo-controlled double-blind trials 总被引:1,自引:0,他引:1
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed
and treated with antibiotics. OBJECTIVE: This study aimed to determine the
evidence for the effectiveness of antibiotic treatment in acute maxillary
sinusitis in adults by assessing the methodological quality of
placebo-controlled double-blind randomized trials. METHOD: An evaluation by
four raters through a 35-item scoring-scale for internal and external
validity of all placebo-controlled double-blind randomized trials on acute
sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five
trials were excluded because they were not placebo-controlled,
double-blind, randomized, or were carried out in patients with chronic
sinusitis or in children. The three remaining trials were performed in
different populations (one in general practice) between 1973 and 1978. Only
one study claimed superiority of antibiotic treatment. Different inclusion
criteria and major outcome measures were used by the authors. The
reliability of major outcome events was reported poorly or not at all and
in two studies outcome measures were clinically inappropriate. The studies
scored 30-62% of the maximum attainable score for internal validity and
10-20% for external validity. CONCLUSION: The effectiveness of antibiotic
treatment in acute maxillary sinusitis in a general practice population is
not based sufficiently on evidence.
相似文献
6.
P Ferranti V Carbone N Sannolo I Fiume A Milone M Ruoppolo M Gallo A Malorni 《Carcinogenesis》1992,13(8):1397-1401
The present study describes how mass spectrometry was extensively applied to the characterization and quantification of modified amino acids within the polypeptide chain of Angiotensin I, chosen as model substrate, combining the use of fast atom bombardment mass spectrometry with gas chromatography--mass spectrometry. The reaction products after in vitro incubation of Angiotensin I with styrene oxide, a well known carcinogen, under different conditions, have been characterized: a prominent reactivity of several potential nucleophilic sites of Angiotensin I was shown, including two histidine residues and a tyrosine residue; it is worth noting that it has never been stated that tyrosine is highly reactive with styrene oxide. The results obtained demonstrate the usefulness of mass spectrometry for the structural determination of chemically modified amino acids in peptides and proteins, and the presence of a reliable relationship between reaction conditions and the production of alkylated amino acids. This characterization procedure offers the possibility of identifying reactive sites following exposure to unknown alkylating agents. 相似文献
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H Angus-Leppan GA Lambert J Michalicek 《Cephalalgia : an international journal of headache》1997,17(6):625-630
Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches. 相似文献
9.
In patients with PG-dependent renal function, NSAID administration
constantly reduces GFR and RBF in a dose-dependent fashion. In this
situation, the risk of overt acute renal failure is high and should be
taken into proper account. In contrast, the incidence of NSAID-related
renal structural alterations appears to be very low, yet the absolute
number of patients may be significant considering the wide use of such
drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable
ratio risk/benefit does not seem to support their indication in proteinuric
nephropathies. The development of PGHS-2 selective inhibitors is promising,
and may open new therapeutical strategies in the treatment of the
progression of renal disease.
相似文献
10.