Search results for " Flow"
showing 10 items of 3127 documents
Blood supply, oxygenation status and metabolic micromilieu of breast cancers: characterization and therapeutic relevance.
2000
The metabolic microenvironment of a tumor is predominantly determined by the efficacy of blood flow, flux parameters (such as diffusion and convective currents in the interstitial space) and metabolic rates. The most important factors in this context include oxygen and nutrient supply, tissue pH and the bioenergetic status. It is now widely accepted that the metabolic microenvironment of a tumor can dramatically influence a range of factors such as proliferation rate, cell cycle position, growth rate and the development of apoptosis and necrosis. At the same time, these parameters can have an impact on tumor detection, therapeutic response to conventional irradiation, some chemotherapy agen…
RCBF-quantification with 99mTc-HMPAO-SPECT: theory and first results.
1989
The activity concentrations of 99mTc-HMPAO in brain after intravenous injection were evaluated in 25 patients using SPECT. With additional first pass studies of heart and brain with the short lived isotope 195mAu, the cardiac output and the mean cerebral transit times of the patients were measured a short time before the HMPAO injection. The time dependence of 99mTc-HMPAO activity in the brain was registered during the first 5 min after injection over both hemispheres. Using a simplified three compartment model it was possible to calculate the mean retention fraction of HMPAO in brain from the time activity curves. It could be shown that the regional cerebral blood flow in ml/min per 100 g …
Pre- and intraoperative methods of controlling cerebral circulation in giant aneurysm surgery.
1995
The surgical treatment of giant aneurysms usually requires temporary clipping of the aneurysmatic vessel. In planning the surgical approach and in applying temporary clips, the surgeon must consider collateral circulations. The functional integrity of the collateral vessels frequently decides the patient's outcome. In 8 patients with internal carotid artery giant aneurysm, measurements of blood flow velocities in the ipsilateral middle cerebral artery were performed preoperatively with transcranial Doppler ultrasound (TCD) during manual occlusion of the carotid artery at the neck. Three different perfusion patterns were established, and each collateral capacity was rated as insufficient, te…
Cerebral blood flow, computerized tomography and angiography in 562 cases of cerebrovascular insufficiency
1987
The measurement of cerebral blood flow (CBF) in addition to cerebral computerized tomography (CT) and angiography is most reliable in cases of transient ischemic attacks (TIA) and prolonged reversible ischemic neurologic deficits (PRIND). Alterations of CBF can be detected in symptom-free intervals. The cerebrovascular reactivity to CO2 stimulus is regarded as an especially suitable tool to prove the cerebrovascular reserve. If it is diminished, cerebral angiography should be carried out since it will often show major obstructive lesions. Angiography shows no sure correlation between CBF and collateral circulation. Strong opthalmic pathways in unilateral occlusion of the internal carotid ar…
Chronic Thromboembolic Pulmonary Hypertension: Pre- and Postoperative Assessment with Breath-hold MR Imaging Techniques
2004
To evaluate the potential of breath-hold magnetic resonance (MR) imaging techniques in morphologic and functional assessment of patients with chronic thromboembolic pulmonary hypertension (CTEPH) before and after surgery.Thirty-four patients with CTEPH were examined before and after pulmonary thromboendarterectomy (PTE). For morphologic assessment, contrast material-enhanced MR angiography was used; for assessment of hemodynamics, velocity-encoded gradient-echo sequences and cine gradient-echo sequences along the short axis of the heart were performed. Contrast-enhanced MR angiography was compared with selective digital subtraction angiography (DSA) for depiction of central thromboembolic m…
Magnetically labeled water perfusion imaging of the uterine arteries and of normal and malignant cervical tissue: initial experiences.
1998
Purpose: The aim of this pilot study was to evaluate a magnetically labeled water perfusion imaging technique as a non-contrast-enhanced approach to demonstrate the uterine artery, its branches, and to assess the cervical uterine blood flow in healthy volunteers and in patients with advanced uterine cervical carcinoma (FIGO IIB-IVA). Methods and Materials: Seven healthy volunteers (mean age, 29 years) and twenty-two patients (mean age, 52 years) with advanced cancer of the uterine cervix (FIGO IIB-IVA) were prospectively examined by magnetically labeled water perfusion imaging at different inversion delay times (300–900 ms). The magnetic resonance imaging (MRI) findings of all patients were…
Freestyle pedicled perforator flaps: safety, prevention of complications, and management based on 85 consecutive cases.
2011
Background: Despite the widespread use of free perforator flaps, pedicled perforator flaps seem not to be as widely accepted, probably because of the fear of vascular complications caused by transfer of a flap attached only by its vascular pedicle, prone to shearing, kinking, and trauma. In this article, the authors report on their experience with 85 consecutive cases, focusing on incidence, prevention, and management of complications. Methods: Eighty-five consecutive cases were treated over 6 years at the Plastic and Reconstructive Surgery Department of the University of Palermo for defects of different causes that were reconstructed with a freestyle pedicled perforator flap, in every regi…
Humidity of Anaesthetic Gases with Respect to Low Flow Anaesthesia
1994
It has been demonstrated in an experimental study in swine using the scanning electron microscope that a rebreathing technique utilising minimal fresh gas flowrates significantly improves climatization of anaesthetic gases. Consequently, effects of various anaesthetic techniques on airway climate must be assessed, which covers the need for suitable measuring devices. Basic principles and methods of humidity measurement in flowing anaesthetic gases include gravimetric hygrometry, dew point hygrometry, wet-dry bulb psychrometry, mass spectrometry, spectroscopic hygrometry and electrical hygrometry. A custom-made apparatus for continuous measurement of humidity and temperature in the inspired…
Monosodium benzoate hypersensitivity in subjects with persistent rhinitis
2004
Background: Very few data are available from the literature on whether nonatopic subjects affected by persistent rhinitis may show the appearance of objective symptoms of rhinitis after the ingestion of food additives such as tartrazine (E102), erythrosine (E127), monosodium benzoate (E211), p-hydroxybenzoate (E218), sodium metabisulphite (E223), and monosodium glutamate (E620). It is still unclear whether the ingestion of food additive may cause, as well, a consensual reduction of nasal peak inspiratory flow (NPIFR). Therefore, we used a double-blind placebo-controlled (DBPC) study to evaluate this hypothesis. Patients and methods: Two hundred and twenty-six consecutive patients (76 male…
Comparison of the effects of salmeterol and salbutamol on clinical activity and eosinophil cationic protein serum levels during the pollen season in …
1995
In atopic asthma there is strong evidence of eosinophils playing an active role in pathogenesis. Some investigations demonstrated that eosinophil cationic protein (ECP) serum levels increased in atopic patients with asthma during pollen season.The aim of the study was to evaluate the effects of short-term (1 week) beta 2-agonist treatment on lung function and eosinophil activity in asthmatic patients.We used an open, randomized, cross-over design to compare the effects of salbutamol (200 micrograms q.i.d.) and salmeterol (50 micrograms b.i.d.) on peak expiratory flow rate (PEFR), blood eosinophil count and serum levels of ECP as a measure of eosinophil activity in 20 mild atopic asthmatics.…