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Biomedical subjects

E Martin

Publications and source records attributed to E Martin.

At least 469 records · Page 26Linked to original sources
PubMed1992

[The accuracy of 4 different oximeters for continuous monitoring of mixed venous oxygen saturation during abdominal aortic surgery].

Several systems for mixed-venous oximetry are now available. There are one three-wave-length system (Abbott) and three two-wave-length systems with (Spectramed) and without automatic correction for hemoglobin or hematocrit (Edwards). The purpose of this prospective randomized study was to compare the different systems and to examine the accuracy of continuous mixed-venous oximetry during abdominal aortic surgery. Eighty patients had a radial artery cannula and one of the following fiberoptic pulmonary artery catheters inserted before induction of anesthesia: Swan-Ganz oximetry TD catheter (Edwards), Swan-Ganz flow-directed oximetry thermodilution paceport catheter (Baxter, Edwards Division), SpectraCath STP (Spectramed), and Opticath (Abbott). Mixed-venous O2 saturation was monitored by oximetry computers: SAT-1 (Edwards), SAT-2 (Baxter, Edwards Division), Hemopro2 (Spectramed), and Oximetrix 3 (Abbott). As a method of reference, mixed-venous blood samples were drawn and immediately analyzed by an OSM3-Hemoximeter. Data sets were obtained at eight predetermined times. Hemoglobin was kept constant at +/- 1 g.dl-1. Continuous oximetry in comparison to in-vitro measurements yielded a correlation coefficient of r = 0.873 (P less than 0.0001) and a value of bias and precision (b +/- p) of -0.9 +/- 2.6% for the SAT-1, r = 0.815 (P less than or equal to 0.0001) and b +/- p = -2.2 +/- 2.5% for the SAT-2, r = 0.901 (P less than or equal to 0.0001) and b +/- p = 0.35 +/- 2.5% for the Hemopro2, and r = 0.920 (P less than or equal to 0.0001) and b +/- p = 0.1 +/- 1.8% for the Oximetrix 3, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta, Abdominal↗
PubMed1992

[Cognitive and psychomotor performance following isoflurane, midazolam/alfentanil and propofol anesthesia. A comparative study].

Mental and psychomotor abilities are impaired to varying degrees after general anaesthesia. This has important implications for the time over which patients are monitored in the recovery room and for the discharge of outpatients after day surgery. The present study was undertaken to compare recovery and mental and psychomotor skills in the first 60 min following general anaesthesia with isoflurane, midazolam/alfentanil and propofol. METHODS. A total of 45 patients undergoing microsurgical lumbar nucleotomy were randomized to three study groups. Group 1 (n = 15): anaesthesia was induced with thiopentone and maintained with isoflurane; group 2 (n = 15): anaesthesia was induced with midazolam and maintained with alfentanil; group 3 (n = 15): anaesthesia was induced and maintained with propofol. Vecuronium was used for muscle relaxation and the lungs were ventilated with a mixture of 66% nitrous oxide in oxygen. The following were checked 15, 30, 45, and 60 min after extubation: choice reaction times and critical flicker fusion for psychomotor testing; the maze test and a modification of the ball-bearing test for discrimination of motor and mental activities; and short- and long-term memory. RESULTS. Immediate recovery did not differ in the three different groups. In all patients psychomotor function was impaired compared with baseline for more than 60 min after general anaesthesia. However, impairment was significantly less pronounced after propofol, and recovery to preanaesthesia values was faster following propofol than after midazolam/alfentanil, and slowest after isoflurane-anaesthesia (Figs. 1, 2). The flicker fusion frequency, a very sensitive parameter for the persisting effects of anaesthetics, was significantly higher following propofol anaesthesia and remained so throughout the entire study period (Fig. 3). By 30 min after extubation, short-term memory was already normal in patients who had undergone propofol anaesthesia, and a statistically significant difference from the midazolam/alfentanil and isoflurane anaesthesia groups was obvious throughout the entire study period. However, no differences in long-term memory were found. At 30 min after propofol anaesthesia all patients were able to perform the ball-bearing test, as against 13 patients following midazolam/alfentanil and 10 patients following isoflurane (Table 3). The maze test was mostly impaired after midazolam/alfentanil anaesthesia. Patients who underwent isoflurane anaesthesia needed the same time for the maze test at 60 min afterwards propofol patients needed after 30 min (Table 2). Side effects, e.g., nausea, vomiting, and double vision, were observed significantly more often in groups 1 and 2 (Table 4). DISCUSSION AND CONCLUSION. The results indicate that in operations of approximately 90 min duration the return of motor and mental abilities is faster following propofol anaesthesia. At 30 min after extubation following propofol anaesthesia patients had test results that allow their transfer from the recovery room, while it took 60 min for patients in the two other groups to reach the same levels of motor and mental function. This is important for the duration of monitoring in the recovery room and, especially, for day case anaesthesia.

Adult↗
PubMed1992

[Separation of urologic tumors cells from Cell Saver blood using a membrane filter. A new method in autotransfusion?].

Tumor cells of three urological longterm cell lines have been labelled with 35[S]-Methionin and added to red cell concentrates. Red cell concentrates rich in tumor cells were passed through a cell saver and two special membranfilters under standard conditions. The 35[S]-Methionin labelled tumor cells were detected by liquid scintillation counting. On an average, only 0.027% of the radioactivity was left after passing through the cell saver and the membran filters in the 12 experiments. If investigations in clinical use of cell-saver and membran filter confirm these results, there will be significant consequences in urological tumor surgery by the possibility of transfusing the salvaged autologous blood.

Blood Component Removal↗
PubMed1991

Nonradical oxidants of the phagocyte type induce the activation of plasmatic single chain- urokinase.

Single chain- urokinase (scu-PA) is the proenzyme of the plasminogen activator urokinase (tcu-PA). In human blood scu-PA is of great stability. Activated phagocytes generate large amounts of single chain- urokinase and of reactive oxidants (chloramines and HOCl). Since these cells participate in physiologic fibrinolysis, we were interested in the interaction between plasmatic scu-PA and chloramines. The oxidants dose dependently induce the activation of plasmatic scu-PA. Optimal activation of scu-PA occurs at about 3-5 mmol/l of chloramine-T. The findings suggest a control mechanism of scu-PA stability/activity by oxidatively modifiable plasma proteins, such as alpha-2-antiplasmin. The oxidation mechanism seems to be mediated by singlet molecular oxygen, an excited oxygen species. Basing on this scu-PA/oxidant synergism a sensitive and fast functional assay of scu-PA in human plasma is presented. Plasmatic inhibitors normally interfering with functional scu-PA measurements are inactivated by addition of chloramine-T, imitating the physiological oxidants generated by activated phagocytes. The scu-PA concentration in plasma of n = 36 healthy individuals has been determined to be 5.8 +/- 1.6 ng/ml. The lower detection limit of plasma scu-PA by the procedure described is about 1.5 ng/ml of plasma. By means of this technique scu-PA concentration during thrombolytic therapy can be measured within minutes in undiluted (direct) plasma samples, allowing adjustments of the scu-PA dosage. The present study gives further credence for a role of singlet molecular oxygen, possibly a new type of locally acting hormones (autacoid), in the regulation of the fibrinolytic pathway.

Adult↗
PubMed1991

Why patients consult and what happens when they do.

OBJECTIVE: To study patients' perceptions of why they consulted the doctor, how ill they thought they were, and what happened in the consultation. To compare patients' perceptions before and after the consultation and to compare these perceptions with those of the doctor. DESIGN: Patients filled in a questionnaire before and after the consultation. The doctor filled a questionnaire in after the consultation. SETTING: Three general practices in Bedfordshire and one in Hertfordshire. PATIENTS: 500 consecutive patients consulting in each practice. MAIN OUTCOME MEASURES: Changes in patients' perceptions and differences between the perceptions of patients and doctors. RESULTS: Doctors perceived patients to be less ill than the patients themselves did. Patients from social classes IV and V and children perceived themselves to be more ill than the average. Patients perceived themselves to be less ill after the consultation. A third of patients attended because doctors had told them to, and a quarter of patients had already tried to treat their problem themselves when they attended the consultation. Doctors' perceptions of the consultation emphasised listening, supporting, and giving advice. Patients' perceptions emphasised prescribing, reassuring, and referring to a consultant. Doctors perceived that they listened, examined, and gave advice less to social classes IV and V than to social classes I, II, and III and gave explanations more often to men than to women. Patients perceived external factors rather than lifestyle factors as being more important in causing their problems. CONCLUSION: Doctors' perceptions of patients' problems differed from those of patients expressed both before and after their consultation. Doctors' and patients' perceptions also differed about the consultation itself. The consultation reassured some patients.

Attitude to Health↗
PubMed1991

Phosphoinositide breakdown is associated with Fc-gamma RII-mediated activation of 5'-lipoxygenase in murine eosinophils.

In this report we present data on the ability of murine eosinophils to generate inositol phosphate derivatives, and their relationship with the activation of 5'-lipoxygenase by a Fc-gamma R-dependent mechanism. The addition of anti-IgG F(ab')2 to mouse eosinophils, previously sensitized with IgG, induces inositol phosphate generation after 2 min and after 10 min of stimulation. Maximal generation of inositol tris and inositol tetrakis phosphate has been detected after 15 min of stimulation, and the optimal concentration of anti-IgG F(ab')2 was found to be 25 micrograms. Inositol tris phosphate formation is also observed at 5 min after the addition of the calcium ionophore A23187 (5 microM). We also report that neomycin, an inhibitor of phosphoinositide-phospholipase C, inhibits Fc-gamma R-mediated phosphoinositide breakdown in a dose-dependent manner (88% inhibition at 150 microM of neomycin). The possible involvement of phosphoinositide breakdown in the activation of 5'-lipoxygenase has been investigated. Using streptolysin-O permeabilized cells and different doses of neomycin that inhibit phosphoinositide breakdown, we have demonstrated a parallel decrease in LTC4 released by these cells, using either A23187 (86% inhibition at 200 microM of neomycin) or anti-IgG F(ab')2 (82.4% inhibition at 100 microM of neomycin). [Ca2+]i elevation has been observed by loading the cells with the fluorescent calcium indicator Fura-2 penta-acetoxy methyl ester and after stimulating with the anti-Fc-gamma RII mAb (2.4G2). It is likely that the activation of murine eosinophils by a Fc-gamma R mechanism stimulates phosphoinositide breakdown as a primary step that leads to the activation of murine 5'-lipoxygenase, producing the formation of leukotriene C4.

Animals↗
PubMed1991

Temporal and spatial analysis of fields generated by eddy currents in superconducting magnets: optimization of corrections and quantitative characterization of magnet/gradient systems.

We propose methods for the spatial and temporal characterization of time-dependent magnetic fields generated by eddy currents after switching gradients. For an on-line determination of the temporal variations of the fields, we extract two terms from the unresolved signal of an extended sample, describing the time evolution of a frequency shift gamma delta Bz(t) and of a decay constant k(t). This procedure allows us to optimize interactively the multiexponential pre-emphasis as well as any spectral volume selection method with respect to eddy currents. Additionally, we suggest an imaging sequence which allows us to determine the spatial distribution of eddy current fields at a chosen time-point after any gradient sequence to be tested. Expansion of these eddy currents fields into spherical harmonic functions proves the existence of a higher order terms, which cannot be corrected by a standard pre-emphasis device, where time constants and amplitudes are adjusted on the X, Y, Z, and Z0 coils. The proposed numerical analysis gives a tool to characterize any magnet/gradient system quantitatively with respect to eddy current performance.

Magnetic Resonance Imaging↗
PubMed1991

MR imaging of intracranial hemorrhage in neonates and infants at 2.35 Tesla.

The variations of the relative signal intensity and the time dependent changing contrast of intracranial hemorrhages on high-field spin-echo magnetic resonance images (MRI) were studied in 28 pediatric patients. For T1-weighted images, a repetition time (TR) of 500 ms and an echo time (TE) of 30 or 23 ms was used. The corresponding times for T2-weighted images were TR 3000 ms and TE 120 ms. Intracranial hematomas, less than 3 days old, were iso- to mildly hypointense on short TR/TE scans and markedly hypointense on long TR/TE scans (acute stage). In the following four days the signal of the hematomas became hyperintense on short TR/TE scans, beginning in the periphery and proceeding towards the center. On long TR/TE scans the signal remained markedly hypointense (early subacute stage). 7-14 days old hematomas were of high signal intensity on short TR/TE scans. On long TR/TE scans they appeared hypointense in the center and hyperintense in the periphery (late subacute stage). By the end of the second week the hematomas were of high signal intensity on all pulse sequences (chronic stage). Chronic hematomas were surrounded by a parenchymal rim of hypointensity on long TR/TE scans. 28 neonates and infants (with 11 follow-up examinations) of 31.5-70.6 weeks postconceptional age (PCA), with an intracranial hemorrhage were examined. The etiologies of the hemorrhages were: asphyxia (17 cases), brain infarct (2), thrombocytopenia (1), clotting disorder (1) and unknown origin (7). The aim of this study was to describe the appearance of intracranial hemorrhages in neonates and infants with MRI at 2.35 Tesla using spine-cho sequences.

Acute Disease↗
PubMed1991

MRI of two infants with tuberous sclerosis.

Two children (4 1/2 and 9 months of age) suffering from tuberous sclerosis were examined with MRI, using a 2.35-Tesla magnet. Both patients showed the typical brain lesions of tuberous sclerosis, namely, subependymal nodules projecting into the lateral ventricles and parenchymal hamartomas. However, in one child the examination revealed subcortical foci of low signal intensity on T2-weighted images and of high signal intensity on T1-weighted images, which could represent fat-containing hamartomas.

Brain↗
PubMed1991

MR imaging of the brainstem: normal postnatal development.

Magnetic resonance imaging (MRI) of the mesencephalon during the first four years of life allowed normal maturational processes of the various midbrain structures in vivo to be followed. Using T2-weighted SE sequences, we found 5 characteristic age dependent patterns on axial tomograms taken at the level of the superior colliculi, that let us derive a grading system for normal development of the quadrigeminal plate, the cerebral peduncles, the reticular substantia nigra and the red nuclei. A subsequent statistical analysis of these age dependent changing patterns on T2-weighted MRI of 60 neonates, infants and small children yielded normal age ranges for each of the 5 maturational stages of the midbrain. Grading the changing pattern of midbrain structures during early postnatal life into 5 distinct maturational stages allowed not only monitoring of normal differentiation, e.g. myelination of the brainstem in vivo, but may also help to distinguish between normal, delayed and abnormal development of the mesencephalon on routine MRI.

Brain Stem↗
PubMed1991

Magnetic resonance imaging in infantile encephalopathy with cerebral calcification and leukodystrophy.

Three children, one pair of siblings and a sporadic case, with "infantile (familial) encephalopathy with cerebral calcification and leukodystrophy" are reported. Neuroimaging studies demonstrated extensive bilateral calcifications particularly in paraventricular location and within the cerebral white matter. MRI, performed in two infants, confirmed marked white matter involvement with diffuse delay of myelination. This condition can be added to the growing list of leukodystrophies.

Brain↗
PubMed1991

Contribution of magnetic resonance imaging in the evaluation of microcephaly.

Magnetic resonance imaging (MRI) was performed in 33 children using a 2,35 T MR system. The intention was to determine the various types of morphological abnormalities seen in primary microcephaly and the frequency with which they occur. MRI findings were typical for cytomegalovirus infection in six patients. Cerebral malformations were found in 14 cases and patchy white matter lesions in both hemispheres in two subjects. MRI appeared to be abnormal in eight of the remaining 11 children. However, we were unable to provide an exact interpretation of the findings. All the children with MRI abnormalities with the exception of two were neurodevelopmentally deviant. Thus, MRI revealed abnormalities in the majority of infants with primary microcephaly and neurodevelopmental disturbances. It appears to be more sensitive than cranial ultrasound and computed tomography.

Brain↗
PubMed1991

Superoxide generation by human neutrophils induced by low doses of Escherichia coli hemolysin.

Escherichia coli hemolysin (Hly) was isolated from bacterial culture supernatants by polyethylene glycol precipitation and centrifugation in glycerol density gradients. The toxin preparations contained less than 1 mol of lipopolysaccharide per 10 mol of protein, and they had no fatty acids. The capacity of purified hemolysin to stimulate superoxide anion production in polymorphonuclear leukocytes was monitored kinetically in a lumimeter by using the lucigenin assay and was correlated with the kinetics of transmembrane pore formation. When applied to leukocytes suspended in protein-free buffer, very low concentrations (0.02 to 0.1 HU/ml) of the toxin strongly stimulated the production of superoxide anions; shortly thereafter, irreversible membrane permeabilization occurred. When the toxin was applied at concentrations exceeding 0.2 to 0.3 HU/ml, membrane permeabilization was so rapid that the cells were unable to mount a respiratory burst. When applied in the narrow range of 0.05 to 0.1 HU/ml, E. coli hemolysin rivaled phorbol myristate acetate in its capacity to stimulate production of superoxide anions. Additionally, hemolysin applied at doses that elicited no pore formation (0.01 to 0.02 HU/ml) primed leukocytes for an augmented response to subsequent challenge by the phorbol ester. These data demonstrate that very low doses of E. coli hemolysin can evoke cellular reactions that appear independent of and precede transmembrane pore formation and cell death.

Bacterial Proteins↗
PubMed1991

Quantitative analysis of opsonophagocytosis and of killing of Candida albicans by human peripheral blood leukocytes by using flow cytometry.

We describe a simple, rapid, automated procedure for measuring opsonophagocytosis and killing of Candida albicans by human peripheral blood leukocytes. Yeast cells are labelled by allowing uptake and cleavage of membrane-permeable bis-carboxyethyl-carboxyfluorescein pentaacetoxymethylester to its membrane-impermeable fluorescent derivative bis-carboxyethyl-carboxyfluorescein. The yeast cells are added to cell-rich plasma obtained after dextran sedimentation of erythrocytes. Opsonophagocytosis and killing are quantified by using automated fluorescent cell analysis, and the following parameters can be obtained: (i) relative percentage of phagocytes that participate in opsonophagocytosis, (ii) relative percentage of yeast cells that become associated with phagocytes, and (iii) percentage of killing of C. albicans. The first two parameters are obtained through the additional use of a phycoerythrin-conjugated monoclonal antibody that selectively labels monocytes and polymorphonuclear granulocytes in peripheral blood. Killing is assessed by solubilizing blood cells with deoxycholate to liberate yeast cells from the phagocytes. Viable yeast cells retain carboxyfluorescein, but nonviable cells lose the fluorescent marker; thus, the reduction in number of fluorescent particles directly reflects phagocytic killing. Results obtained by the present method correlated excellently with parallel enumerations by colony counting. Test results with seven healthy individuals revealed a marked dissociation between the process of opsonophagocytosis, which was essentially complete after 20 min at 37 degrees C, and killing rates, which were 48% +/- 11% and 63% +/- 9% (standard deviation) after 1 and 2 h, respectively, when yeast cell-to-phagocyte ratios were in the range of 0.5:1 to 2:1. The described assay is unrivaled in simplicity, rapidity, and reproducibility and generates results for a large number of samples within hours.

Candida albicans↗
PubMed1991

Primary structure and biological activity of human brain-derived neurotrophic factor.

Brain-derived neurotrophic factor (BDNF) is a 27-kDa basic protein of noncovalently linked 13.5-kD subunits related to nerve growth factor and is produced by the central nervous system (CNS). BDNF has been shown to promote the survival of neurons located in or directly connected with the CNS and is likely to function in adjusting the cell number within neuronal populations to the need of this projection field. Here we describe the primary structure of a human BDNF cDNA, the biological activities of pure recombinant human BDNF, and the tissue distribution of rat BDNF. BDNF mRNA can be found in some peripheral tissues as well as in the CNS, and recombinant human BDNF is a potent neurotrophic factor for primary peripheral sensory neurons.

Amino Acid Sequence↗
PubMed1991

Metaphors of bleeding in women.

All women experience bleeding throughout their life cycle, usually in a normal context. However, throughout history bleeding has been described metaphorically in negative ways. This paper presents an anthropologist's viewpoint concerning the presentation of bleeding in the literature.

Attitude to Health↗