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Biomedical subjects

J Pradel

Publications and source records attributed to J Pradel.

At least 55 records · Page 3Linked to original sources
PubMed1991

[The posterior interparieto-peritoneal or retroperitoneal spaces. 2: Pathological x-ray computed tomographic image].

The old reports about the interparieto-peritoneal spaces described particularly the renal space and its environment. The CT scan has modified the in vivo study of the extraperitoneal spaces (E.P.S.) and brought the question of the acquired knowledge up again. An anatomical research was performed in the first part of this study which describes the structures limited between the parietalis fascia and visceral peritoneal fascias. These are the true EPS which the main element is the propria fascia of Sappey (lateroconal fascia) and its anterior and posterior renal double layers. All these lamellar structures limits spaces variably infiltrated with fat tissue: the anterior pararenal space almost virtual, the posterior pararenal space which continues till the Bogros space and the anterior and posterior renal spaces of the renal compartment which the fat continues till the bladder and accompanies the ureter. The second part of this study precises some notions of general topography which are necessary for reading abnormal CT scan images. This part reminds the aortic and arterial general organization of the vertebrates as described by Mackay. It underlines the architectural importance of the three areas so defined: parietal or peripheral, intermediate or mesoblastic genitourinary and deep lateral or digestive endoblastic. These three areas corresponds to the three vascular aortic circles. It emphasized the importance to accept in practice the notion of visceral joining fascia which has been proved in adult people. The longitudinal architecture of the compartments is precise with respect to their appartenance to one among the three arterial arches of Mackay. What the anatomy suggest, the pathology can prove. Several pathological processes are studied on CT scan: large hemorrhagic or necrotic collections in acute pancreatitis, abnormalities or diseases of renal or adrenal compartments, extraperitoneal mesenchymomas, diseases of the psoas compartment. All these observations are analysed in order to explain anatomical and CT scan findings. This study refers not only to the oldest researches which are still valuable but also to the most recent controversies. All the questions are not solved using the clearest schemes.

Abdomen↗
PubMed1990

[Role of imaging in the exploration of the adrenal glands].

Currently, the major method of adrenal gland imaging is computed tomography. This method allows demonstration of normal adrenals and the diagnosis of adrenal masses (if these are greater than 1 cm in diameter). The examination should be directed by clinical signs and known laboratory investigations. Computed tomography is therefore the first line investigation to perform. Certain lesions may be better demonstrated by other methods: MRI and MIBG scintigraphy offer a greater specificity in the investigation of pheochromocytomas. In addition, scintigraphy can identify possible ectopic tumours or recurrences. Selective catheterisation of the adrenal veins allows aldosterone and cortisone secretions to be assayed. There remains the problem of the incidental finding of adrenal masses in either an asymptomatic patient or in the context of investigation of spread of a know cancer. These lesions may benefit from diagnostic percutaneous guided biopsy.

Adrenal Gland Neoplasms↗
PubMed1989

Modulo, a new maternally expressed Drosophila gene encodes a DNA-binding protein with distinct acidic and basic regions.

We have cloned, following an immunological screen of an expression library, five cDNA clones encoding the modulo antigen, a DNA-binding protein differentially expressed during Drosophila development. In addition a series of overlapping cDNA and genomic clones were also isolated. This protein is the product of a 2.2 kb mRNA that is encoded by a single genetic locus (100F). Analysis of the complete 544 amino-acid sequence, deduced from nucleotide sequence of cDNAs, shows that the polypeptide exhibits a primary structure with distinct charged regions, a modular structure found in several eukaryotic nuclear proteins, either transcription regulators or structural factors. The amino and carboxyl termini are rich in basic residues. The first third of the sequence contains a long domain comprised almost entirely of glutamic and aspartic acid residues. A typical cAMP dependent phosphorylation site and five potential glycosylation sites have been detected in the amino-acid sequence. Computer searches fail to reveal any significant homology with known proteins. Developmental pattern of transcription of the modulo gene indicates that messengers are maternally provided to the embryos and that zygotic transcription is required during subsequent development.

Amino Acid Sequence↗
PubMed1989

Expression of laminin and of a laminin-related antigen during early development of Drosophila melanogaster.

This paper reports the characterization of two immunologically related proteins that may be involved in cell adhesion during Drosophila development. These proteins, laminin chain A and a 240K component, share the epitope recognized by monoclonal antibody RD3 (Mab RD3). The two antigens show different developmental expression profiles. Laminin is detected only from 6 to 8 h of development onwards; its concentration increases during embryogenesis to reach steady-state value in larvae, pupae and adult flies. By contrast, the 240K antigen, not found in oocytes, is present before blastoderm stages; its concentration increases during gastrulation, decreases at the end of organogenesis and the antigen is no longer detected in third instar larvae. Light and electron microscope immunolocalization in imaginal discs indicates that laminin is distributed apically in the lumen and basally in the basal membrane that surrounds the nonevaginated disc. During morphogenesis laminin is detected at the basal side of the evaginating part of the disc epithelium. Immunolocalization on paraffin sections of early embryos suggests that the 240K antigen is related to (1) cell formation and polarization in association with cytoskeleton components, (2) establishment of cell-extracellular substratum interactions during the blastoderm cell sheet organization and (3) basement membrane deposition during embryonic germ cell layer segregation. This 240K protein is poorly or not glycosylated, is resistant to chondroitinase ABC and collagenase and appears therefore as a new extracellular component that might be specifically involved in early processes of morphogenesis.

Animals↗
PubMed1987

Nuclear antigens differentially expressed during early development of Drosophila melanogaster.

To obtain specific immunological probes for studying molecular events involved in gene activation during early development of Drosophila, we have produced monoclonal antibodies directed against nuclear proteins differentially expressed in time and space during embryogenesis. Twenty-five antibodies against nuclear antigens detected after the onset of zygotic genome transcription were obtained. These antigens have been distributed into six categories depending on their reactivity in dot-blot, in Western-blot and in immunofluorescence on embryo frozen section assays. Six antigens (fifth and sixth categories) are stage-, but not tissue-specific and are present in all nuclei of the embryo after the blastoderm stage. Ten antigens, the third and fourth categories, did not react on immunofluorescence and have not been characterized for a possible tissue specificity. Antigens of the first and second categories are stage- and tissue- specific. Two of them are of particular interest. The first (250 kd, recognized by the monoclonal antibody GB7) is preferentially expressed in nuclei of the ventral nerve cord, whereas the other (65 kd, recognized by the monoclonal antibody LA9) is located in nuclei of the gut and associated structures.

Animals↗
PubMed1985

Cystic renal cancers: CT characteristics.

The preoperative distinction between renal cyst and tumor has long been a dilemma. A cystic renal adenocarcinoma may appear similar to a largely necrotic tumor or a cancer incorporated into a cyst or arising from a cyst wall. Overall, these cystic cancers present the same preoperative features. In our series of 15 cases, the characteristic pattern on computed tomography scans included size greater than or equal to 10 cm, localized thickening of cyst walls with contrast enhancement, and irregularly and poorly defined implantation in the kidney.

Adenocarcinoma↗
PubMed1984

Local recurrence after nephrectomy for primary renal cancer: computerized tomography recognition.

We diagnosed by computerized tomography 15 local recurrences in 88 patients who had undergone nephrectomy for renal cancer, with no false positives and 1 false negative. This over-all low rate (17 per cent) probably is owing to the fact that computerized tomography scans were done in patients in good clinical condition. Local recurrence was noted in 3 of 59 asymptomatic patients and in 12 of 19 patients with local symptoms. No recurrence was noted in 10 patients with general symptoms. Thus, 20 per cent of local recurrences were asymptomatic and 80 per cent presented with local symptoms. High local recurrence rates were found in cases of transitional cell carcinoma with whole wall involvement or extension to adjacent tissues (4 of 8 patients, 50 per cent), clear cell adenocarcinoma with lymph node involvement (3 of 7 patients, 43 per cent) and partial nephrectomy (3 of 6 patients, 50 per cent). Therefore, we consider such patients to be at high risk. Our study demonstrates that computerized tomography enables earlier, accurate diagnosis of smaller local recurrence in asymptomatic patients and provides a sensitive, reliable, noninvasive, repetitive method of evaluation of clinical treatment trials. Routine followup should be reserved for high risk patients.

Adenocarcinoma↗
PubMed1983

Sodium cromoglycate, verapamil and nicardipine antagonism to leukotriene D4 bronchoconstriction.

1--The effects of nicardipine, verapamil and sodium cromoglycate (SCG) on the increase in pulmonary airway resistance(RAw) and decrease in pulmonary dynamic compliance (CDyn) induced by leukotriene D4 (LTD4) 0.5 micrograms kg-1 and acetylcholine (ACh) 3 micrograms kg-1 were investigated in anaesthetized guinea-pigs. The effects of these three agents on the contractile effects of LTD4 and ACh were tested on isolated tracheal preparations of the guinea-pig. 2--Nicardipine and verapamil (0.3 and 1 mg kg-1), as well as SCG (3 and 10 mg kg-1), partially but significantly inhibited the effects of LTD4 on RAw. Partial inhibition of the effect of LTD4 on CDyn was only observed with verapamil (0.3 and 1 mg kg-1). Nicardipine and verapamil had no effect on ACh-induced bronchoconstriction in vivo. 3--In concentrations higher than 10(-5) M, nicardipine and verapamil inhibited the contractile effects of LTD4 and ACh on guinea-pig isolated trachea. SCG had no effect on this preparation. 4--These results suggest that nicardipine, verapamil and SCG partially reduce the component of bronchoconstriction associated with stimulation of irritant receptors by LTD4. However, the site and mechanism of action of Ca2+-entry antagonists remain uncertain.

Airway Resistance↗
PubMed1983

Radiological evaluation of the peri- and pararenal spaces by computed tomography.

Computed tomography (CT) gives an excellent opportunity to revisit normal anatomy and to understand pathological aspects. Renal fascia alterations, on CT scans, are a sensitive sign of local lesion. While a thin renal fascia has no pathological significance, any thickening may be considered abnormal although nonspecific. It is found in pancreatitis as well as in cancer of the pancreas, in renal tumors as well as in pyelonephritis. It may persist as a scar. On the other hand, lack of fascial thickening allows us to rule out renal extension of a neighboring lesion or to decide that a renal mass is an ancient slowly-growing benign one.

Abscess↗
PubMed1982

Computed tomography versus aortography in diagnosis of aortic dissection.

The use of computed tomography (CT) versus aortography is evaluated in a limited study of 17 cases of aortic dissection (AD). With the constraints of the present state of the technology and lack of availability of CT scanners at some centers, aortography remains the premier and often the only diagnostic test to choose in an emergency. CT, however, may be an asset in the diagnosis of AD when: (1) atypical or misleading clinical presentations are evident that do not require aortography; (2) aortography is contraindicated in a weakened patient, when there is no emergency; (3) aortography is a risk while there is a strong suggestion of AD; (4) patency of a false channel must be confirmed. These circumstances were encountered in five patients. In addition, a localized infrarenal AD was fortuitously discovered in two patients presenting with abdominal visceral cancer. On patient follow-up, CT is less invasive and may be performed in asymptomatic patients undergoing treatment, thereby facilitating the early detection of complications. Detailed computed tomograms often yield superior diagnostic information only if the CT study includes rapid sequential scans immediately following a fast intravenous bolus of contrast material.

Aged↗
PubMed1981

On the activation of fructose-1,6-bisphosphatase of spinach chloroplasts and the regulation of the Calvin cycle.

Activation by light of spinach fructose-1,6-bisphosphatase is mimicked by dithiothreitol. This process of activation by dithiothreitol implies the specific reduction of two disulfide bridges and a conformation change of the enzyme that makes eight sulfhydryl groups available. The activated enzyme has an apparent allosteric kinetic behavior with respect to both fructose 1,6-bisphosphate and magnesium.

Binding Sites↗
PubMed1981

Substrate-binding isotherms of spinach chloroplastic fructose-1,6-bisphosphatase and the photoregulation of the Calvin cycle.

Fluorescence titration experiments of chloroplastic fructose-1,6-bisphosphatase by fructose bisphosphate and magnesium have been effected using the inactive dimeric, the inactive tetrameric and the active tetrameric enzyme forms. Magnesium binding to the inactive dimeric enzyme exhibits a positive cooperativity whereas fructose 1,6-bisphosphate exhibits no cooperativity at all. The binding of either magnesium or fructose bisphosphate to the inactive oxidized tetramer exhibits a succession of negative and positive cooperativities (mixed cooperativity). Upon reduction of the inactive tetramer by dithiothreitol and activation, the ligand binding properties of the enzyme are changed. Magnesium and fructose bisphosphate are bound to the active enzyme with a positive cooperativity. Non-linear least-square fitting allows one to estimate thea binding constants, and therefore the free energy of binding of either magnesium or fructose bisphosphate to the various forms of the enzyme. Whatever the state of fructose-1,6-bisphosphatase, one ligand is bound per subunit. The affinity constants of magnesium for the active or inactive enzyme forms are much greater than those of fructose bisphosphate. This suggests that the metal ion gives to the enzyme the right conformation to bind the sugar phosphate.

Binding Sites↗