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C Rumio

Publications and source records attributed to C Rumio.

6 recordsLinked to original sources
PubMed1997

Identification of type 1 5alpha-reductase in myelin membranes of male and female rat brain.

The formation of the 5alpha-reduced metabolites of testosterone (T) and of progesterone (P) is a very active process in the brain, since the enzyme 5alpha-reductase (5alpha-R) is present in almost any central nervous system (CNS) structure. A particularly elevated 5alpha-R activity has been shown in myelin sheaths. Two isoforms of the enzyme have been cloned, with different localisation as well as different biochemical properties. The present study was performed to determine whether both isoforms of the 5alpha-R, or only one of them, are/is responsible for the enzymatic activity observed in myelin. Kinetic analyses have been performed on purified myelin membranes prepared from the male or female rat brain, using both T and P as substrates. The 5alpha-R present appears to possess a pH optimum at basic values. The Vmax values obtained in the Lineweaver-Burk analysis were comparable in male and female preparations independently on whether T or P were used as the substrates, suggesting that a single enzymatic form is present in all samples examined; the Km obtained using [14C]T (Km: male 1.14 microM; female 1.46 microM) or [14C]P (Km: male 0.5 microM; female 0.64 microM) as substrates, were in good agreement with those obtained for the recombinant type 1 isoform. These data suggest that the type 1 isoform is the most relevant 5alpha-R present in myelin. To confirm this, a new polyclonal antibody was raised against the type 1 5alpha-R enzymatic protein, and used in immunohistochemical studies. The experiments were performed on the optic nerve, a myelinated structure very rich in 5alpha-R activity and the results clearly indicated the presence of a specific type 1 enzyme immunoreactivity in the myelin sheaths of axons.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1995

A simple method for overcoming some problems when observing thick reflective biological samples with a confocal scanning laser microscope.

A simple device is described, which allows the range of depth of scanning to be reduced when observing thick reflecting biological samples with a confocal scanning laser microscope (CSLM). Thick histological sections of human skin and rat brain stem were mounted between two coverslips ('sandwich' style) and the optical tomography was performed from both sides by turning the 'sandwich' upside-down. The samples were impregnated using standard Golgi-Cox, 'rapid Golgi' or other silver methods. The ability to turn the 'sandwich' upside-down is particularly useful when the reflective structure inspected is deep inside the section, i.e., near the lower surface of the specimen, or when it is opaque to the laser beam or excessively reflective.

Animals↗
PubMed1995

Three-dimensional reconstruction of the Meissner corpuscle of man, after silver impregnation and immunofluorescence with PGP 9.5 antibodies using confocal scanning laser microscopy.

The 3-dimensional organisation of the neural component of the human Meissner corpuscle was studied after silver impregnation and following immunofluorescence for protein gene product 9.5 (PGP 9.5) by confocal scanning laser microscopy. The morphology of the Meissner corpuscle was found to show consistent differences depending on the labelling method used. After silver impregnation by the Winkelmann technique the branches of the afferent nerve fibres of the corpuscle showed both thin regions and varicose elements, the latter probably corresponding to the portions rich in mitochondria observed by transmission electron microscopy. The bulkier elements were never more than 5-6 microns in diameter. After immunolabelling for PGP 9.5 the nerve fibre branches in the corpuscle always presented flattened and discoidal expansions with a diameter of up to 30 microns. On the basis of what is known as to the mechanism of action of silver impregnations it is considered that the black precipitate preferentially labels the parts of neurons that are rich in neurofilaments. In any case the precipitate is deposited throughout the neuronal cytoplasm except in the mitochondria and the nucleus. Accordingly, in the varicosities of the Meissner corpuscles that are rich in mitochondria, there is little space for the formation of the precipitate. The use of antiserum against PGP 9.5, which labels the larger proteinaceous component of the axoplasm, demonstrates the complete architecture of the neural component of the Meissner corpuscle, and visualises the discoidal and flattened expansions which are absent in the impregnated corpuscles. It is concluded that immunostaining provides images of the corpuscles, and of peripheral neural structures that are in general closer to reality.

Antibodies, Monoclonal↗
PubMed1994

Localization of nitric oxide synthase immunoreactivity in mast cells of human nasal mucosa.

Nitric oxide (NO)-synthase immunoreactivity has been detected for the first time in mast cells of human normal nasal mucosa, with an antibody specific for neuronal NO-synthase. Intense immunoreactivity was revealed in secretion granules of mast cells but was found in mast cell granules free in the extracellular matrix only in some instances; no reactivity was found in the cytoplasm of this or other cell types. These findings suggest that human nasal mast cells contain a particulate isoform of NO-synthase, which shares epitopes with neuronal NO-synthase and is rapidly removed from granules upon exocytosis.

Amino Acid Oxidoreductases↗
PubMed1994

Central and peripheral nervous structures as seen at the confocal scanning laser microscope.

Central neurons and peripheral nervous structures, e.g. cutaneous free endings, perifollicular nets, Meissners corpuscles and intramuscular fibres, were studied using various impregnation methods. The confocal scanning laser microscopes (CSLMs) used were equipped with different laser sources, in order to evaluate their limitations and advantages with these techniques and to contribute to a better understanding of the general morphology of the nervous system. When staining with silver sections with clouds of tiny silver granules which are beyond the resolution power of the conventional light microscope but which show a high reflectivity with the CSLM are obtained. Golgi-Cox mercuric impregnation, however, provides specimens which are precipitate-free, thus ensuring the reliability of information obtained. It does, however, have the disadvantage of being applicable only to the central nervous system. In all cases it is an advantage for the instrument to be fitted with different lasers (e.g. Ar and He-Ne), so as to optimize the images of samples impregnated with different methods. Notwithstanding the possibility that artefacts may distort the geometry of the sample and reduce the resolution, the images presented in this paper show that with careful selection of optical sectioning distances, the use of a suitable stack of sections and, if necessary, the aid of false electronic colours and of partial or complete rotation, it is possible to achieve a more precise interpretation of the morphology and organization of complex structures, such as those of the nervous system.

Animals↗