PubMed Health⌕ Search

Biomedical subjects

D Meier

Publications and source records attributed to D Meier.

At least 91 records · Page 5Linked to original sources
PubMed1990

Comparison of propofol and thiopental/halothane for short-duration ENT surgical procedures in children.

Experiences with propofol in pediatric anesthesia are limited. We undertook a study to evaluate the quality of induction and recovery from anesthesia with propofol compared to thiopental/halothane. Twenty children received 3 mg.kg-1.min-1 of propofol as a loading dose followed by a maintenance dose of 0.1 mg.kg-1.min-1 (+/- 10%). Twenty children received 5-7 mg/kg of thiopental, and maintenance was provided with halothane (0.5%-1.5%). The interval between the end of the administration of propofol or thiopental/halothane and extubation, as well to discharge to the ward, was significantly shorter with propofol (4.4 versus 13.5 min and 7.22 versus 30.4 min, respectively). Spontaneous movements and pain on injection were seen significantly more frequently with propofol, whereas laryngospasm and hiccup were only observed with thiopental. During the first 6 h after the surgical procedure, analgesics were needed significantly more often in the thiopental group. Nausea and vomiting also were observed more frequently in the thiopental group. In conclusion, propofol used as a single anesthetic is a satisfactory technique for ENT surgery of short duration in children.

Anesthesia, Inhalation↗
PubMed1989

[Adenocarcinoma of the ethmoid sinus in a woodworker: apropos of a case].

We report the case of a 69 year old male who developed an ethmoidal adenocarcinoma in 1984, after having worked as a woodworker for 35 years. Although the relationship between wood dust and ethmoidal cancer has been known since 1965, the exact etiological agent is not identified up to now. A good knowledge of the clinical picture together with the means of screening and the investigations which are available make it possible to identify up to 86% of localised tumours.

Adenocarcinoma↗
PubMed1989

Increased rf power absorption in MR imaging due to rf coupling between body coil and surface coil.

Fears have been voiced that excessive tissue heating could occur in the event that first, a surface coil is placed with its axis parallel to the transmitting rf field leading to a maximal coupling of the two coils and second, the decoupling circuit of the surface coil breaks down. To avoid an rf coupling of the transmitting body coil to the receive-only surface coil, conventionally applied surface coils are equipped with an active electronic rf decoupling circuit. In extensive worst-case experiments on phantoms we have shown that no tissue heating occurs for surface coils which are equipped with semiconductor varicap diodes for tuning and matching. These coils should be safe for patient applications even if the decoupling circuit fails. Surface coils equipped with mechanically variable capacitors are generally passively decoupled. To simulate the worst-case situation phantom experiments were performed in which a surface coil of this type having no passive decoupling circuit was coupled to the transmitter coil by its geometric position. Theoretical calculations, in agreement with the experimental results achieved during a 15-min measurement in a 1.5-T MRI whole-body imager, show that a significant rf power deposition in the tissue underneath the coil wire occurs, leading typically to a local specific absorption rate of 24 W/kg and a local temperature rise of 5.2 degrees C.

Electric Conductivity↗
PubMed1989

Velocity profiles in the normal human abdominal aorta: a comparison between ultrasound and magnetic resonance data.

Evolving magnetic resonance (MR) procedures were utilized to validate one-dimensional ultrasonic (US) Doppler profiles in vivo on the basis of this alternative noninvasive method of assessing blood velocity. Corresponding velocity profiles were acquired by both US and MR in the abdominal aorta of 10 healthy volunteers. The ultrasound velocities recorded throughout a cardiac cycle along the anterio-posterior aortic diameter were compared to their spatial and temporal MR counterparts. Correlation coefficients ranging from 0.92 to 0.97 and regression slopes from 0.86 to 1.13 indicate a high degree of correspondence between the two modalities and increase the confidence in the fidelity of velocity profiles obtained with both procedures.

Adult↗
PubMed1989

Human abdominal aorta: comparative measurements of blood flow with MR imaging and multigated Doppler US.

Magnetic resonance (MR) imaging has proved to be a new alternative method for the noninvasive detection and quantification of blood flow in human vessels. By means of standard gradient echo sequences triggered with electrocardiography on a 1.5-T whole-body imaging system, the authors measured the flow-induced phase shift in the abdominal aorta of healthy volunteers. The instantaneous two-dimensional velocity profiles and the integrated flow rate were determined in intervals down to 21 msec throughout the cardiac cycle. The results were validated by means of comparative measurements with a multigated Doppler ultrasound instrument. The velocity values acquired with this instrument in one spatial dimension in the anteroposterior direction of the abdominal aorta agreed to a great extent with the temporal and spatial corresponding values recorded with MR imaging. The same high correlation between the two methods was found for the calculated instantaneous total blood flow.

Adult↗
PubMed1989

[Mammography and ultrasound in the diagnosis of clinically occult breast cancer].

105 biopsies of nonpalpable breast lesions were performed because of suspect X-ray findings. 68 lesions were preoperatively marked under X-ray control, 37 under ultrasound control. Histological examination revealed invasive and in situ carcinomas in 8 and 13% of the cases, respectively. The sensitivity of X-ray mammograms was superior to ultrasound, whereas the predictive value of ultrasound in the presence of suspect findings was superior to x-ray examination. However, because of its low sensitivity, sonographic examination cannot be recommended as a screening procedure in the diagnosis of nonpalpable breast lesions.

Biopsy↗
PubMed1988

Heating effects of metallic implants by MRI examinations.

Magnetic radiofrequency fields applied in magnetic resonance imaging examinations induce electrical currents in metallic implants. These eddy currents may heat up the implants and thus may be capable of causing localized tissue heating. The rf power deposition and the joule heating of the implant can be calculated by solving Maxwell's equations for the specific problem. First, extreme in vitro worst-case experiments were performed with a large and very thin aluminum sheet, which was placed in a 1.5-T MRI device in a position parallel to the magnetic rf field. In agreement with the theoretical results the temperature rise of a thermally insulated sheet amounted to only 0.08 degrees C after a 15-min MRI examination at 64 MHz. No temperature rise in the aluminum sheet could be measured for a sheet immersed in a saline solution. Second, in vitro experiments with a hip joint prosthesis and an osteosynthetic plate were performed to confirm the theoretical results, which predict nearly no temperature rise in the metallic implants. No temperature rise in the implants could be measured.

Aluminum↗
PubMed1988

Quantitative flow measurements on phantoms and on blood vessels with MR.

A broad spectrum of MR methods has been published in the last few years for the visualization and the quantification of flow in human blood vessels. We describe the results of an extended study to measure the flow quantitatively using the MR phase modulation method. A gradient echo sequence which allows short repetition times was synchronized with the ECG. The instantaneous velocity profiles and the integrated flow rate can be determined throughout the cardiac cycle in up to 45 consecutive time intervals. The instantaneous velocity distributions can be displayed as 2D profiles over the lumen of the blood vessel. The technique has been successfully evaluated with a set of phantom experiments. Following this, quantifications of the blood flow rates in vivo were performed on the abdominal aortas of healthy volunteers. The MR flow results were compared to those obtained with conventional Doppler ultrasound examinations. The results of both methods are in good quantitative agreement.

Aorta↗
PubMed1988

T and B cell specific immune responses to purified protein derivative in the cerebrospinal cavity may be maintained and regulated independently of systemic immune control.

In vivo activated T cells could be isolated from cerebrospinal fluid (CSF) of a patient suffering from chronic meningitis of unclear origin. Although the patient's skin reactivity to purified protein derivative (PPD) was negative, and peripheral T cells did not proliferate to this antigen in vitro, the majority of T cell clones from CSF specifically recognized PPD on either autologous or allogeneic HLA class II compatible macrophages. Remarkably, peripheral blood mononuclear cells potently suppressed the PPD-specific proliferative responses of healthy donors. The selective enrichment of oligoclonal IgG in the CSF but not in the patient's serum further indicated T and B cell responses lacking systemic feedback control. Analyses of a persisting immune stimulation in the CSF provide a potent diagnostic tool and may explain neurological complications as observed in a number of autoimmune diseases and chronic infections.

Adult↗
PubMed1987

Free amino acid pattern of cerebrospinal fluid in meningeal pathology.

Free amino acid concentrations of CSF were measured in bacterial meningitis, aseptic meningitis, meningoradiculitis Garin-Bujadoux-Bannwarth, multiple sclerosis, carcinomatous meningitis, and controls. Almost all CSF amino acids were highly elevated in bacterial but not in aseptic meningitis, meningoradiculitis Garin-Bujadoux-Bannwarth or carcinomatous meningitis thus providing a laboratory tool for their differential diagnosis. In carcinomatous meningitis the amino acid pattern indicates metabolic activity of tumor cells. Minimal alterations were found in multiple sclerosis which have no diagnostic value.

Adult↗
PubMed1982

Immunoselection of oligodendrocytes by magnetic beads. II. In vitro maintenance of immunoselected oligodendrocytes.

Oligodendrocytes isolated by immunoaffinity on magnetic beads using a monoclonal antibody to oligodendrocyte cell surfaces were obtained with a purity of 91 +/- 4% [see companion paper, Meier et al, 1982]. Contaminating cells consisted mostly of tetanus toxin-positive neurons with small cell bodies. Very few glial fibrillary acidic protein-positive astrocytes and fibronectin-positive fibroblasts or fibroblast-like cells could be detected by indirect immunofluorescence. Macrophages, as identified by their characteristic morphology, were rarely detectable in the cultures. With increasing time in culture, the degree of homogeneity of the cultured oligodendrocytes increased slightly, while the cell density of oligodendrocytes decreased drastically within the first week of culture. Cultures of immunoselected oligodendrocytes with a lower degree of purity showed a better survival of oligodendrocytes, but a considerable reduction in purity after three weeks in culture, probably due to overgrowth of nonoligodendroglial elements.

Animals↗