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Biomedical subjects

J de Mey

Publications and source records attributed to J de Mey.

At least 19 recordsLinked to original sources
PubMed2006

Duodenal diverticulitis: CT and MR findings.

We report a case of duodenal diverticulitis and describe the helical computed tomography and contrast-enhanced magnetic resonance imaging (MRI) study findings. Due to its uncommon appearance, this lesion is not typically included in the differential diagnosis of pancreatitis or cholecystitis. The imaging findings of duodenal diverticulitis can be very suggestive of its diagnosis or can narrow the differential diagnosis. To our knowledge and in spite of the wide use of MRI, the contrast-enhanced MRI features of this entity, as described below, have not yet been reported in the literature.

Aged↗
PubMed2006

CT analysis of defects of the cement mantle and alignment of the stem: in vitro comparison of Charnley-Kerboul femoral hip implants inserted line-to-line and undersized in paired femora.

Using a modern cementing technique, we implanted 22 stereolithographic polymeric replicas of the Charnley-Kerboul stem in 11 pairs of human cadaver femora. On one side, the replicas were cemented line-to-line with the largest broach. On the other, one-size undersized replicas were used (radial difference, 0.89 mm sd 0.13).CT analysis showed that the line-to-line stems without distal centralisers were at least as well aligned and centered as undersized stems with a centraliser, but were surrounded by less cement and presented more areas of thin (< 2 mm) or deficient (< 1 mm) cement. These areas were located predominantly at the corners and in the middle and distal thirds of the stem. Nevertheless, in line-to-line stems, penetration of cement into cancellous bone resulted in a mean thickness of cement of 3.1 mm (sd 0.6) and only 6.2% of deficient and 26.4% of thin cement. In over 90% of these areas, the cement was directly supported by cortical bone or cortical bone with less than 1 mm of cancellous bone interposed. When Charnley-Kerboul stems are cemented line-to-line, good clinical results are observed because cement-deficient areas are limited and are frequently supported by cortical bone.

Arthroplasty, Replacement, Hip↗
PubMed2000

Real time CT-fluoroscopy: diagnostic and therapeutic applications.

The synergetic progression of CT technology and computer hardware has made ultrafast acquisition and image reconstruction possible. This has lead to the availability of CT interactive diagnosis and therapeutic procedures. Making use of our own material (337 intervention procedures during the last 17 months), we have compared our techniques and results to the recent literature data. One of the advantages of the biopsy technique is an improved sensitivity for neoplastic lesions, most certainly in cases of intrapulmonary lesions, surrounded by aerated tissue (now 94% compared to 87% in our previous study). A second advantage is the safety of the technique (only one major complication in our series). Fluid collection drainages, and more complex interventions like local injection of drugs, radio-frequency ablation, wire hook placement and ethanol injection were performed without complication. Yet another interesting feature is the shortening of the procedure time (reduced in average to an 'in-room' time of less than 30 min), which has definite economical implications. Furthermore it increases the patient's comfort and safety, and extends the scope of outpatient procedures (80% outpatient procedures in our material). On the other side the radiation exposure can be raised as an issue, especially when we consider the operator's hands. However, the described technique and the use of dedicated tools can alleviate the problem. As a conclusion, real time CT fluoroscopy has given a new input and broadens the scope of clinical indications of CT-guided diagnostic and therapeutic procedures.

Adolescent↗
PubMed1999

[Computed tomography-guided diagnostic puncture in abdominal pathology].

Technological improvements (short-time acquisition and reconstruction, CT, spiral technique) together with better puncture material and a general trend towards less invasive surgical procedures have had a combined effect to a wider scope of applications for percutaneous punctures under CT-guidance. In this paper, we analyze and discuss recent data in the literature on puncture material, indications and results. The relevant choice of the needle model and its diameter, depending on the organ and suspected pathology, as well as the point of entry and the puncture track are key factors granting procedure safety, ambulatory use and good diagnostic results.

Abdomen↗
PubMed1998

Partial peripheral neuropathy and denervation induced adrenoceptor supersensitivity. Functional studies in an experimental model.

Sciatic nerve ligation in rats (chronic constriction injury (CCI)) induces clinical signs and symptoms that mimic human conditions of neuropathic origin, such as reflex sympathetic dystrophy (RSD). Denervation-induced supersensitivity to (circulating) catecholamines has been implicated in sympathetic dysfunction in the CCI model as well as in RSD. In the present paper we studied functional properties of sympathetic innervation in subcutaneous resistance arteries, isolated from the hind paw of rats 3 weeks after ligation. Contractile responses to electric field stimulation of adrenergic nerves and exogenously administered cumulative doses of various adrenergic agonists were studied using a myograph. As compared to the contralateral side, subcutaneous arteries from the ligated side were less responsive to electrical field stimulation. Besides, as compared to the contralateral side, subcutaneous arteries from the ligated side showed increased sensitivity to alpha 1-adrenoceptor stimulation. This study demonstrates that sympathetic dysfunction in an experimental model of neuropathic pain consists of denervation-induced supersensitivity to catecholamines rather than of an afferently-induced increase in efferent sympathetic nerve impulses.

Adrenergic Fibers↗
PubMed1997

Picture archiving and communication system (PACS): medical perspectives.

PACS represents the natural evolution from the digital new modalities (US, CT, MRI,...) to a global digital environment, where the film based activities are progressively replaced by their digital counterpart. The advantages of the technique, as well as the drawbacks of the first implementations, are described. The "second generation" PACS concept is presented (modular architecture, progressive implementation, multivendor environment, integration with the Hospital Information System, standardization,...). As "case study", the example of the A.Z.-V.U.B. Hospital Implementation is described.

Computer Communication Networks↗
PubMed1996

Picture archiving and communication system (PACS): a progressive approach with small systems.

PACS represents the natural evolution from working with digital modalities (e.g. CT, US, MRI, CR) towards a global digital environment where the film based activities are progressively replaced by their digital counterpart. The advantages of the technique and the drawbacks of the first implementations are described, as well as the recent advances in terms of technology, architecture, medical integration and cost-effectiveness. The so called 'second generation' PACS concept is presented with its features: modular architecture, progressive implementation, multi-vendor environment, integration with the Hospital Information System, standardization. This approach is particularly suited for progressive implementation in an existing hospital, in contrast to the possible top-down construction of a filmless radiology department, as a project for a totally new hospital. The implementation into the university hospital AZ-VUB is described as case study.

Radiology Department, Hospital↗
PubMed1995

[Spiral CT of vascular liver lesions].

Computed tomography (CT) has an important and undisputed role as a screening modality for suspected focal liver disease. Improvements in CT technology have dramatically increased our ability to detect and diagnose liver abnormalities. Spiral CT allows rapid imaging of the liver, resulting in improved contrast dynamics compared to conventional CT techniques. The timing of contrast administration and scan acquisition has become critical. With inadequate timing, lesions that in optimal conditions are easily visualized, can be ignored. Arterial phase imaging should be used when potential hypervascular neoplasms are suspected, and if possible, should include both arterial and portal venous phase imaging to ensure maximal lesion detection and visualisation of vascular structures. Portal venous phase imaging alone is optimal for evaluating most hypovascular tumors. This article reviews the principles of lesion detection and, to a lesser degree, lesion characterization. Special interest is focused on hypervascular lesions.

Carcinoma, Hepatocellular↗
PubMed1984

Ultrastructural localization of alpha-actinin and filamin in cultured cells with the immunogold staining (IGS) method.

Monospecific antibodies to chicken gizzard actin, alpha-actinin, and filamin have been used to localize these proteins at the ultrastructural level: secondary cultures of 14-d-old chicken embryo lung epithelial cells and chicken heart fibroblasts were briefly lysed with either a 0.5% Triton X-100/0.25% glutaraldehyde mixture, or 0.1% Triton X-100, fixed with 0.5% glutaraldehyde, and further permeabilized with 0.5% Triton X-100, to allow penetration of the gold-conjugated antibodies. After immunogold staining (De Mey, J., M. Moeremans, G. Geuens, R. Nuydens, and M. De Brabander, 1981, Cell Biol. Int. Rep. 5:889-899), the cells were postfixed in glutaraldehyde-tannic acid and further processed for embedding and thin sectioning. This approach enabled us to document the distribution of alpha-actinin and filamin either on the delicate cortical networks of the cell periphery or in the densely bundled stress fibers and polygonal nets. By using antiactin immunogold staining as a control, we were able to demonstrate the applicability of the method to the microfilament system: the label was distributed homogeneously over all areas containing recognizable microfilaments, except within very thick stress fibers, where the marker did not penetrate completely. Although alpha-actinin specific staining was homogeneously localized along loosely-organized microfilaments, it was concentrated in the dense bodies of stress fibers. The antifilamin-specific staining showed a typically spotty or patchy pattern associated with the fine cortical networks and stress fibers. This pattern occurred along all actin filaments, including the dense bodies also marked by anti-alpha-actinin antibodies. The results confirm and extend the data from light microscopic investigations and provide more information on the structural basis of the microfilament system.

Actinin↗
PubMed1982

Principles for the morphological characterization of transmitter-identified nerve cell groups.

Principles for a morphometric description of transmitter identified nerve cell groups have been introduced, exemplified on the 5-HT nerve cell group of nucleus raphe dorsalis (B7 cell group), using immunocytochemical procedures to visualize 5-HT. Both cell body parameters (mean diameter, mean perimeter, mean area, shape factor) and cell group parameters (number of cells, mean free distance among cells, volume fraction, gravity centre, major axis slope with respect to the midline) have been considered. These parameters have been obtained by the use of a semiautomatic image analyzer (Kontron MOP AMO2) plugged into an Apple II computer. By the use of this system and of suitable computer programs, it is possible to give a Cartesian representation of 5-HT nerve cell bodies in a coronal section under study. The present work has mainly one aim. To detect whether subgroups exist within a transmitter-identified cell group. Two approaches have been introduced to obtain, on objective grounds, evidence whether or not a group consists of subgroups. The first of these approaches is based on differences in cell body density within the cell group, while the second approach is based on frequency distribution analysis. This second approach is mainly sensitive to shape changes of the cell group.

Animals↗
PubMed1981

Sequential use of the PAP and immunogold staining method for the light microscopical double staining of tissue antigens.

Double immunoperoxidase staining using different couplers can give various combinations of colours on a single tissue section to achieve a comparable picture of different antigens. However, the colour combinations achieved to date are not entirely satisfactory. A double immunostaining procedure is introduced here, combining the peroxidase anti-peroxidase (PAP) and immunogold staining (IGS) methods. The IGS method is a new, simple, sensitive and reliable approach to immunostaining at the light microscopic level. It was carried out in three ways. Firstly, a two-step method was used in which the second layer was goat anti-rabbit IgG absorbed onto gold particles (GAR/Au20). Secondly, a three-step method was employed where the second layer was unlabelled goat anti-rabbit IgG and the third layer was a rabbit antibody to peroxidase absorbed onto the gold particles (RAP/Au20) and acting as a gold-labelled IgG antigen. The third method combined the first two methods using GAR/Au20 as th second layer and RAP/Au20 as the third layer which increased the amount of bound gold and enhanced the red colour, providing a better picture. The use of gold-labelled antibodies in double immunostaining has great potential value for many studies including that of the diffuse neuroendocrine system of the gut.

Animals↗
PubMed1981

Regulatory peptides in endocrine cells and autonomic nerves: electron immunocytochemistry.

Advances in immunocytochemistry, particularly at the electron microscope level, have enabled us to establish further details of the ultrastructural appearance of endocrine cells and autonomic nerves of the gastrointestinal tract. Its contribution can be summarised as follows: a)validation of previously recognised endocrine cell types. b) Recognition of sub-groups within endocrine cells and autonomic nerve cell types previously included within one single type (e.g. D1 cells and p-type autonomic nerves). c) Discrimination of molecular forms now known to be stored in morphologically distinguishable secretory granules or parts thereof (e.g. pro-glucagon and glucagon in A cells and gut and antral gastrin-producing cells). Advances in the techniques and the accurate quantification of the end products will enable us to recognise changes in gastrointestinal tract diseases in man.

Animals↗
PubMed1978

[Pancreatic polypeptide (author's transl)].

Pancreatic Polypeptide (PP) was first described in birds by Kimmel et al. (1968). It was later isolated from the pancreas of several mammalian species by Chance and Jones (1974). It has been demonstrated in the islets of many animal species by immunocytochemical methods. PP levels are assayable in plasma and rise sharply after food intake. The pharmacological properties and physiological role of PP are still ill defined. It appears to have a spectrum of actions peculiar to each species. Recent research on this subject is reviewed in this article. High levels of circulating PP have been demonstrated in juvenile and maturity-onset diabetics, as well as in some patients with islet cell tumors. However no definite clinical syndrome due to hypersecretion of PP as been identified as yet. It remains a matter of speculation that a deficiency of PP might be responsible for some types of obesity. PP-cells are rare in the pancreas of healthy young individuals. Hyperplasia of PP-cells has been observed in a wide variety of pathological conditions, but is most prominent in the pancreas of chronic insulin dependent diabetics. Histologic evidence strongly suggests that PP-cell hyperplasia represents an atypical form of islet regeneration. It is always focal in distribution and is most remarkable in those lobules that have lost the capacity to reproduce islets of normal cytologic composition.

Adenoma, Islet Cell↗
PubMed1976

Identification, in the external region of the rat median eminence, of separate neurophysin-vasopressin and neurophysin-oxytocin containing nerve fibres.

Immuno-enzyme cytochemical investigations, using single and double staining techniques, showed that the external region of the rat median eminence contains separate neurophysin-vasopressin fibres and neurophysin-oxytocin fibres. These neurophysin-hormone containing nerve fibres are influenced by bilateral adrenalectomy and by colchicine treatment. The external region of the median eminence of the homozygous Brattleboro rat contains neurophysin-oxytocin fibres. It does not contain immuno-reactive neurophysin-vasopressin fibres. Bilateral adrenalectomy also influences the neurophysin-vasopressin containing neurons of the suprachiasmatic nuclei. In the neurons of the parvicellular part of the rat hypothalamic paraventricular nuclei, staining for vasopressin and for oxytocin is completely absent.

Adrenalectomy↗
PubMedDate not supplied

Toxic intrathoracic goiter and mediastinal lymphadenopathy: an unusual presentation of systemic primary AL amyloidosis.

Mediastinal lymphadenopathy and goiter have been associated with primary amyloidosis, although not in the same patient. One previous case report described the association of an amyloid goiter and hyperthyroidism (due to Graves' disease) with primary amyloidosis. Till now no case reports of patients presenting simultaneously with mediastinal lymphadenopathy, intrathoracic amyloid goiter and hyperthyroidism as the first manifestation of systemic primary (idiopathic) amyloidosis have been described. The present case report describes the clinical, biological radiological and histological features in such a male patient.

Aged↗
PubMedDate not supplied

Health screening with CT: prospective assessment of radiation dose and associated detriment.

The use of computed tomography (CT) for screening of targeted diseases is gaining much interest in the international medical community. An important aspect in the justification of screening with such a high dose examination is the radiation dose to the patient. The objective of this study was to perform a prospective assessment of the radiation dose and associated risk for deleterious effects from a CT screening programme. The excess lifetime risk of fatal cancer for various screening strategies was quantified by estimating the effective dose and by using age dependent mortality risk factors. The accrued data shows that the excess mortality risk due to screening with CT could be substantial. It ranges from 0.01% up to a few percent, strongly depending on the type and method of screening. Consequently, radiation dose and associate risk should be included as fundamental parameters for outlining and deciding a screening approach with CT. Recent technical developments, such as tube current modulation, are promising tools for dose reduction within the constraint of desired image quality.

Abdomen↗