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Biomedical subjects

J Lamy

Publications and source records attributed to J Lamy.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Three-dimensional immunoelectron microscopy of scorpion hemocyanin labeled with a monoclonal Fab fragment.

An immunocomplex of the 4 x 6-meric hemocyanin of the scorpion Androctonus australis with the monoclonal Fab fragment L104 was reconstructed from electron micrographs of a negatively stained specimen, using the double-carbon-layer technique. The resulting structure enables a clear visualization of the Fab fragments bound to the four copies of the Aa6 subunit and directly confirms a previous localization of the L104 epitope deduced from two-dimensional image processing. Despite a strong flattening effect produced by the negative-staining technique the orientations of the Fab fragments are well characterized. Moreover, the observation of a central hole within the elbow bends of the Fab fragments provides information about the disposition of the Fabs around their main axis.

Animals↗
PubMedDate not supplied

Architecture of native human alpha 2-macroglobulin studied by cryoelectron microscopy and three-dimensional reconstruction.

The architecture of the native human alpha 2-macroglobulin was studied by cryoelectron microscopy and image processing techniques. The lip, padlock, doughnut, and four-petaled flower views of this homotetrameric proteinase inhibitor were observed in the frozen-hydrated specimen, and a new view, termed eye view, was also characterized. The present three-dimensional reconstruction demonstrates that all these electron microscope views derive from a single three-dimensional structure. The molecule is composed of two horizontal bodies and of two oblique arches, which border a large central cavity. The polymorphism and the flexibility of the native alpha 2-macroglobulin are discussed.

Freezing↗
PubMedDate not supplied

Three-dimensional reconstruction of Androctonus australis hemocyanin labeled with a monoclonal Fab fragment.

An immunocomplex formed by the 4 x 6 meric hemocyanin of the scorpion Androctonus australis with the monoclonal antibody L104 was studied by cryoelectron microscopy and subjected to three-dimensional (3D) reconstruction. The reconstructed particle reflects the structure of the immunocomplex in its hydrated state and is devoid of the flattening that was previously observed with a negatively stained preparation. A 3D fitting of the X-ray data of the Panulirus interruptus hemocyanin and of the Fab R19.9 to the reconstruction volume allowed the first quantitative measurement of the structural parameters of the antigen, and the localization of the epitope at the surface of subunit Aa6. The independent alignment of the Fabs and the hexamers provides a direct verification for the accuracy of the fit and allows the building of the most detailed model of a cheliceratan 4 x 6meric complex and its attached monoclonal antibodies.

Animals↗
PubMedDate not supplied

Electron microscopy of alpha 2-macroglobulin with a thiol ester bound ligand.

In order to covalently bind the hydrolyzed thiol ester groups of the human alpha 2-macroglobulin (alpha 2M) transformed by methylamine, the phospholipase A2 (PLA2), a small enzyme (M(r) = 13,000) from Naja nigricollis snake venom was activated by succinimidyl 4-(maleimidomethyl)cyclohexane-1-carboxylate (SMCC). Average images determined from electron micrographs of the methylamine-transformed alpha 2M, with and without activated PLA2, were determined by image processing and compared. A localization of the PLA2 was achieved by subtracting the average image of alpha 2M transformed by methylamine from that containing PLA2. The results are consistent with previous work showing the central localization of chymotrypsin trapped in alpha 2M. They also suggest that the four thiol esters are located near the center of the alpha 2M molecule.

Animals↗
PubMedDate not supplied

[Detection of excessive chronic alcoholic consumption and control of withdrawal. Comparative study of respective values of the mean red-cell volume and serum gamma-glutamyl-transferase activity].

The routine detection of chronic alcoholism is necessary during any medical examination whether private or in hospital, or in occupational medicine. The practitionner now has available a simple reliable and cheap test. It consists of the serum estimation of gamma-glutamyl-transferase (gammaGT) and interpretation of the average red cell volume supplied by automatic counting of the red cell. Out of 120 chronic alcoholic subjects ; 67% has a gammaGT increased and 44% had macrocytosis. Under the influence of weaning, there was a rapid fall in gammaGT and a slower reduction in average red cell volume. gammaGT estimation was thus a more sensitive test than M.C.V. for the detection of chronic alcoholics and the control of withdrawal. Its association with the rise in immunoglobulin A-transferrin ratio which we have suggested permits the detection of almost all chronic alcoholics in the population studied.

Acyltransferases↗