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Biomedical subjects

G Marchal

Publications and source records attributed to G Marchal.

At least 217 records · Page 12Linked to original sources
PubMed1994

Sonographic diagnosis of ischemic colitis.

An abdominal ultrasound examination performed on two patients with abdominal pain showed segmental wall thickening of the colon that proved to be due to ischemic colitis. In one case, the typical "target lesion" was recognized. These findings could be confirmed with computed tomography, whereas a single contrast enema was unable to demonstrate the ischemic disease. In the second case, a typical five-layered structure of the bowel wall could be demonstrated. It is concluded that US can be useful in the early diagnosis of colonic ischemia.

Cecum↗
PubMed1994

Simultaneous occurrence of developmental venous anomalies and cavernous angiomas.

PURPOSE: To study the clinical and radiologic findings in 15 patients presenting with both developmental venous anomalies and cavernous angiomas and to determine which lesions caused the acute clinical symptoms. METHODS: Lesions were infratentorial in 7 patients and supratentorial in 7 other patients. In one patient the developmental venous anomaly was infratentorial and the cavernous angioma supratentorial. In all 15 patients clinical examination and CT were performed. In 10 patients MR was performed at the time of the initial CT scan. In 5 patients only late MR is available. RESULTS: Acute clinical signs were present in 9 patients (epilepsy, hemiplegia, meningeal signs, cranial nerve deficit). On CT the cavernous angioma was missed in 9 patients, in 6 patients because of acute hemorrhage. On MR the cavernous angioma was missed in 1 of 2 cases with acute hemorrhage but seen in all other patients. On repeat MR all cavernous angiomas were correctly identified. On CT, 11 developmental venous anomalies were seen. On MR all developmental venous anomalies were seen. CONCLUSIONS: The frequent association of developmental venous anomalies and cavernous angiomas is confirmed. MR is superior to CT in the detection of both cavernous angiomas and developmental venous anomalies. Furthermore our data support the hypothesis that cavernous angiomas and not the developmental venous anomalies cause the acute clinical symptoms because of hemorrhage.

Adult↗
PubMed1994

Focal fatty infiltration of the liver associated with important mass effect.

A case of focal fatty infiltration of the liver (FFIL) with partly multinodular appearance and significant mass effect on computed tomography (CT) is presented. Mass effect in FFIL is sometimes seen with alcoholic liver disease and makes the differential diagnosis with malignant disease often difficult. Diagnosis of FFIL was confirmed on 1.5 T MR images.

Adult↗
PubMed1993

Isolation of a proline-rich mycobacterial protein eliciting delayed-type hypersensitivity reactions only in guinea pigs immunized with living mycobacteria.

Effective protection against a virulent challenge with Mycobacterium tuberculosis is induced only by a previous immunization with living attenuated mycobacteria, usually bacillus Calmette-Guérin (BCG). Living and killed bacteria share a number of common antigens. To identify and to purify molecules that are dominant antigens during immunization with living bacteria, a two-step selection procedure was used. Quantitative delayed-type hypersensitivity (DTH) reactions elicited in guinea pigs immunized either with living or with killed BCG were used to select or counterselect antigens present in BCG culture filtrates. Each major fraction eluted from a series of HPLC columns (gel filtration, DEAE, reverse-phase chromatography) was assayed and titrated on guinea pigs of each group. A protein with an unusual amino acid composition (40% proline, 12% threonine) was purified and N-terminally sequenced. To our knowledge, the sequence Thr-Pro-Pro-Xaa-Glu-Xaa-Pro-Pro-Pro-Pro-Gln-Xaa-Val-Xaa-Leu has not been previously reported. The protein was 100-fold more potent on guinea pigs immunized with living bacteria than on guinea pigs immunized with dead bacteria to elicit a DTH reaction.

Amino Acid Sequence↗
PubMed1993

PET imaging of cerebral perfusion and oxygen consumption in acute ischaemic stroke: relation to outcome.

We used positron emission tomography (PET) to assess the relation between combined imaging of cerebral blood flow and oxygen consumption 5-18 h after first middle cerebral artery (MCA) stroke and neurological outcome at 2 months. All 18 patients could be classified into three visually defined PET patterns of perfusion and oxygen consumption changes. Pattern I (7 patients) suggested extensive irreversible damage and was consistently associated with poor outcome. Pattern II (5) suggested continuing ischaemia and was associated with variable outcome. Pattern III (6), with hyperperfusion and little or no metabolic alteration, was associated with excellent recovery, which suggests that early reperfusion is beneficial. This relation between PET and outcome was highly significant (p < 0.0005). The results suggest that within 5-18 h of stroke onset, PET is a good predictor of outcome in patterns I and III, for which therapy seems limited. The absence of predictive value for pattern II suggests that it is due to a reversible ischaemic state that is possibly amenable to therapy. These findings may have important implications for acute MCA stroke management and for patients' selection for therapeutic trials.

Aged↗
PubMed1993

Posterior fossa dermoid cyst associated with dermal fistula: report of 2 cases and review of the literature.

Two cases of dermoid cysts of the posterior fossa in association with a dermal fistula and with different clinical presentations are reported. The patient in case 1 is a 14-month-old girl with a history of recurrent bacterial meningitis. Case 2, a 7-year-old girl, presented with a skin "granuloma" at the inion. Both cases, and a review of the literature, demonstrate the need for a thorough exploration of the cranial and spinal midline skin areas in every newborn and argue for widespread use of nuclear magnetic resonance imaging whenever a suspected midline lesion is found.

Brain Neoplasms↗
PubMed1993

Image segmentation: methods and applications in diagnostic radiology and nuclear medicine.

We review and discuss different classes of image segmentation methods. The usefulness of these methods is illustrated by a number of clinical cases. Segmentation is the process of assigning labels to pixels in 2D images or voxels in 3D images. Typically the effect is that the image is split up into segments, also called regions or areas. In medical imaging it is essential for quantification of outlined structures and for 3D visualization of relevant image data. Based on the level of implemented model knowledge we have classified these methods into (1) manual delineation, (2) low-level segmentation, and (3) model-based segmentation. Pure manual delineation of structures in a series of images is time-consuming and user-dependent and should therefore be restricted to quick experiments. Low-level segmentation analyzes the image locally at each pixel in the image and is practically limited to high-contrast images. Model-based segmentation uses knowledge of object structure such as global shape or semantic context. It typically requires an initialization, for example in the form of a rough approximation of the contour to be found. In practice it turns out that the use of high-level knowledge, e.g. anatomical knowledge, in the segmentation algorithm is quite complicated. Generally, the number of clinical applications decreases with the level and extent of prior knowledge needed by the segmentation algorithm. Most problems of segmentation inaccuracies can be overcome by human interaction. Promising segmentation methods for complex images are therefore user-guided and thus semi-automatic. They require manual intervention and guidance and consist of fast and accurate refinement techniques to assist the human operator.

Algorithms↗
PubMed1993

Comparison between Gd-DTPA, Gd-EOB-DTPA, and Mn-DPDP in induced HCC in rats: a correlation study of MR imaging, microangiography, and histology.

The behaviour of two liver-specific contrast MR agents, Gd-EOB-DTPA and Mn-DPDP and one nonspecific contrast agent, Gd-DTPA, was compared in a rat model of chemically induced hepatocellular carcinoma (HCC). The study included contrast enhanced MR imaging and the corresponding microangiography and histology. Analysis of the MR images showed similar degrees of maximum relative liver enhancement: 47.5 +/- 8.2% for Gd-EOB-DTPA (0.03 mmol/kg) at 5 min postinjection and 52.5 +/- 14.4% for Mn-DPDP (0.025 mmol/kg) at 15 min; both exceeded the value obtained with Gd-DTPA (34.8 +/- 13.6%, at 5 min), even at 0.3 mmol/kg. Gd-EOB-DTPA caused a similar "negative" enhancement of all types of HCC, independent of their differentiation and vascularization, i.e., lesion-to-liver contrast-to-noise ratio (CNR) of differentiated and undifferentiated HCC increased negatively from, respectively, 1.9 +/- 1.1 and -5.1 +/- 3.1 before contrast to -5.2 +/- 2.4 and -11.8 +/- 4.8 at 5 min after contrast. On Mn-DPDP enhanced images, the undifferentiated HCCs showed up negatively (CNR -5.5 +/- 4.7 before contrast to -13.7 +/- 10 at 15 min after contrast), whereas the more differentiated tumors showed up positively (CNR from 2.3 +/- 2.0 before contrast to 12.5 +/- 3.5 at 24 hr postcontrast) due to active uptake and delayed elimination of Mn-DPDP.

Angiography↗
PubMed1993

BCG-induced protection in guinea pigs vaccinated and challenged via the respiratory route.

Since studies on cellular immune responses have demonstrated the role of the mucosal lymphoid system of the respiratory tract, we have studied responses obtained from the local respiratory route, compared to the systemic intradermal route, of BCG immunization. Guinea pigs vaccinated with different doses of BCG via both routes served to follow lymphoid cell proliferation, hilar lymph node and lung BCG clearance, lung granuloma formation and protection induced after virulent challenge. Results demonstrate that the aerogenic route of vaccination with BCG has no harmful side-effects for the host. In comparison with the intradermal route of vaccination, aerogenic vaccination with 10(5) BCG cfu induced higher local cellular immune responses and a substantially improved protective effect.

Administration, Inhalation↗
PubMed1993

The uptake of manganese dipyridoxal-diphosphate by chemically induced hepatocellular carcinoma in rats. A correlation between contrast-media-enhanced magnetic resonance imaging, tumor differentiation, and vascularization.

OBJECTIVES AND RATIONALE: Negative enhancement of implanted liver tumors has been achieved in preclinical studies on manganese dipyridoxal-diphosphate (Mn-DPDP), a new hepatobiliary specific contrast agent for magnetic resonance imaging (MRI). The authors investigated the effects of Mn-DPDP on primary liver cancer and its possible mechanisms. METHODS: Magnetic resonance imaging was performed in 15 rats with chemically induced hepatocellular carcinoma (HCC) before and after Mn-DPDP injection. Both tumor-liver contrast-to-noise ratio and absolute tumor enhancement were evaluated and compared with the MRI results of a nonspecific contrast agent, gadolinium-DOTA, and correlated with corresponding microangiographic and histologic findings. RESULTS: Mn-DPDP injection led to a persistent positive enhancement in differentiated solid HCCs (22/23) with maximal conspicuity at 24 hours. Undifferentiated HCCs were all delineated by a prompt negative enhancement (20/20) with maximal conspicuity within 30 minutes.

Angiography↗
PubMed1993

Identification of a Mycobacterium bovis BCG 45/47-kilodalton antigen complex, an immunodominant target for antibody response after immunization with living bacteria.

Increased protection against a virulent challenge with Mycobacterium tuberculosis is induced mainly by a previous immunization with living avirulent mycobacteria, usually Mycobacterium bovis BCG. Only a transient and marginal protection is obtained after immunization with bacterial extracts or dead bacteria. Both living and heat-killed bacteria share a number of common antigens. In order to identify mycobacterial molecules which are dominant antigens during immunization with living bacteria, a two-step selection method was used. Two groups of guinea pigs were immunized either with living or with heat-killed BCG. Sera were then collected and used to select and counterselect antigens present in BCG culture filtrates. Each major fraction eluted from a series of high-pressure liquid chromatography columns (gel filtration, DEAE, and reverse-phase chromatography) was run on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred on polyvinylidene difluoride sheets. The molecules present on twin immunoblots were stained with antibodies raised in guinea pigs immunized either with living or with heat-killed BCG. Cross-reactive antigens stained in twin immunoblots were eliminated. Major antigens interacting with antibodies raised after immunization only with living bacteria were further purified. A complex of 45- and 47-kDa major molecules (45/47-kDa complex) was thus identified and further purified. The complex was found to interact only with antibodies present in sera of guinea pigs immunized with living bacteria and not at all with antibodies raised after immunization with dead bacteria. The 45/47-kDa antigen complex molecules were resolved on two-dimensional electrophoresis in three major and seven minor proteins detected with silver staining. All the molecules interacted with the antibodies present in sera of guinea pigs immunized with living BCG. The three major proteins (two at 47 kDa and one at 45 kDa) were amino-terminal sequenced. The sequence A-P-E-P-A-P-P-V-P-P-A-A-A-A-P-P-A, which was not previously reported, was the same for these three molecules. By using a competitive enzyme-linked immunosorbent assay, the concentrations of the 45/47-kDa antigen complex were measured in BCG culture filtrates, freeze-dried BCG, and dried heat-killed BCG; they were, respectively, 2, 0.01, and 0.001% of the total mass. The low or very low values compared with the high antibody concentration emphasized the ability of the 45/47-kDa complex delivered through live BCG to trigger an antibody response.

Amino Acid Sequence↗
PubMed1993

Experimental liver cancers: Mn-DPDP-enhanced rims in MR-microangiographic-histologic correlation study.

During both animal and clinical studies with manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (DPDP), enhanced rims around liver tumors on magnetic resonance (MR) images have been observed. To elucidate the origins of these rims and to assess their potential value in the differential diagnosis of liver masses, the authors studied 15 rats with induced hepatocellular carcinoma (HCC), 10 rats with implanted Novikoff hepatomas, and 11 rabbits with implanted VX2 carcinomas. A total of 69 primary and secondary liver cancers from these three animal models were studied. Mn-DPDP- and gadolinium tetraazacyclododecantetra acetic acid (DOTA)-enhanced MR images were compared. On the Mn-DPDP-enhanced images, 34 peritumoral rims of various patterns were displayed, all of which were exclusively related to the presence of highly malignant primary and secondary liver tumors. Peritumoral zones of malignant infiltration, surrounding parenchymal compression, and bile duct proliferation were seen to be the origin of these rims after comparison of MR images with the corresponding microangiograms and histologic specimens.

Angiography↗
PubMed1993

Duodenal leiomyosarcoma.

We present a case of duodenal leiomyosarcoma studied with computerized tomographic (CT) and magnetic resonance (MR) images. Some differential diagnostic remarks are mentioned. The topographic abilities of MR to determine the exact origin of the tumor are stressed. A stellar "scar", hypointense on T1 and hyperintense on T2-weighted images (1 Tesla) in association with gastrointestinal leiomyosarcoma was, at least to the best of our knowledge, never mentioned before in the literature.

Adult↗
PubMed1993

Value of MRI in the diagnosis and staging of testicular tumors.

Ultrasound is currently the primary imaging modality for the assessment of scrotal disease. In acute pathology, colour Doppler adds further confirmation about blood flow to the testicles and surrounding structures. MR is emerging as a powerful tool to image the scrotum. Compared with sonography, MR has a wider field of view and a greater tissue contrast. The current status of MR imaging and its role in the evaluation and local staging of testicular tumors is evaluated in this retrospective study. MR is able to differentiate seminomatous from non-seminomatous tumors in nearly all cases. However, stromal tumors (e.g. Leydig cell tumors) cannot be differentiated from seminomatous tumors, and some benign lesions, as an intratesticular hematoma, cannot be differentiated from non-seminomatous tumors. Microscopic extension in or beyond the tunica albuginea cannot be evaluated.

Dysgerminoma↗
PubMed1992

[Cerebral and cardiovascular aging and brain energy metabolism. Studies with positron-emission tomography in man].

Positron emission tomography (PET) is the only method that measures concomitantly in the same cerebral region the main haemodynamic (blood flow, blood volume) and metabolic (oxygen and glucose consumption) parameters, thereby providing essential data concerning the supply of substrates by circulation and their principally neuronal/synaptic use by the cells. In "healthy" (i.e. normal) ageing, there is a progressive decrease of oxygen and glucose consumption--with subsequent reduction of cerebral blood flow (CBF)--which predominates in the neocortex and suggests a dysfunction of neuronal circuits perhaps responsible for some age-related changes in cognitive functions. The metabolic depression in the neocortex seems to be accentuated during the more "common" ageing which may include cerebrovascular risk factors, lesions of the white matter in varying numbers and/or degradation of cognitive functions. Strategically located brain lesions of vascular origin (e.g. damaging of the thalamic nuclei), may produce a thalamo-cortical disconnection which induces a diffuse cortical hypometabolism associated with severe cognitive disorders. In degenerative dementias (particularly Alzheimer's disease), which include cortical and subcortical neuronal lesions (e.g. those involving the cholinergic system), there is a hypometabolism preferentially affecting the associative cortex. The cumulative effects on cortical functioning of multiple vascular lesions, superimposed on degenerative neuron loss, might account for age-related cognitive disorders in "normal" ageing as well as in the so-called "vascular" or "mixed" dementias.

Adult↗
PubMed1992

Regional cerebral oxygen consumption, blood flow, and blood volume in healthy human aging.

Using high-resolution positron emission tomography and the oxygen 15 continuous inhalation method, we examined the changes in cerebral metabolic rate of oxygen, blood flow, blood volume, and oxygen extraction fraction as a function of age in 25 optimally healthy, unmedicated volunteers who ranged in age from 20 to 68 years. Subjects were strictly selected for absence of cerebrovascular risk factors, dementia, or mental disorders; they had neither biological nor clinical abnormalities, and no focal anomaly on computed tomographic scan. Regions of interest were determined according to the anatomical structures defined on corresponding computed tomographic scan cuts obtained using a stereotaxic head-positioning method. This same method was also used for positron emission tomographic imaging. There was no significant effect of aging on PaCO2 values, hematocrit, arterial blood pressure, cholesterol and triglyceride levels, and blood glucose levels. In most cerebral cortex gyri, the cerebral metabolic rate of oxygen significantly decreased with age according to a linear pattern, with the same magnitude (about -6% per decade) in all four lobes and on both sides. This effect of age on cortical cerebral metabolic rate of oxygen persisted when the possible influence of cortical atrophy, gender, and head size were partialled out. In contrast, the white matter, deep gray nuclei, thalamus, and cerebellum were not significantly affected. The cerebral blood volume declined with a similar pattern to cerebral metabolic rate of oxygen, while changes in cerebral blood flow were less significant, presumably because of larger variance of data across subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗