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Biomedical subjects

P Wild

Publications and source records attributed to P Wild.

At least 109 records · Page 6Linked to original sources
PubMed1986

The genome of bovine herpesvirus 1 (BHV-1) strains exhibiting a neuropathogenic potential compared to known BHV-1 strains by restriction site mapping and cross-hybridization.

Bovine herpesvirus 1 (BHV-1) strains can be differentiated by their DNA and polypeptide patterns, and by antigenic properties as demonstrated by monoclonal antibodies. We classified the BHV-1 strains according to these data as BHV-1.1, BHV-1.2 (a/b) and BHV-1.3 (a/b). BHV-1.1 and BHV-1.2 correspond to the well known 'common' BHV-1 strains, whereas BHV-1.3 has only recently been recognized and exhibits a neuropathogenic potential. In the present paper we describe the structural genome characteristics of BHV-1.3 compared to those of the other BHV-1 strains, examined by means of restriction site mapping, electron microscopy and cross-hybridization. Our results also confirm and complete data concerning BHV-1.1 and BHV-1.2 published by other authors. The following main conclusions can be drawn from our investigations: BHV-1.1 and BHV-1.2 differences are restricted to distinct genomic regions, characterized by loss or gain of restriction sites. BHV-1.3, however, differs from the other BHV-1 strains in restriction site alterations throughout the whole genome. Electron microscopy showed the typical BHV-1 DNA structure for BHV-1.3. Genetic homology between BHV-1.1 and BHV-1.2, reported to be about 95%, was confirmed by cross-hybridization, and a similar high base sequence homology for BHV-1.3 could be shown.

Animals↗
PubMed1986

Ultrastructural alterations in mammalian parathyroid glands induced by fixation.

The influence of fixation methods, buffers and ions on the ultrastructure of parathyroid cells was studied in dogs, cats, rats and mice. Parathyroids fixed by immersion showed 3 chief cell variants referred to as cells in active, intermediate and resting stages, multinucleated syncytial cells, atrophic cells and, only in 1 feline parathyroid, a few oxyphil cells. Parathyroid glands fixed by perfusion, however, consisted only of 1 cell type. Satisfactory preservation was achieved by perfusion with 2.5% glutaraldehyde in 0.1 M Na cacodylate containing 0.25 mM CaCl2 and 0.5 mM MgCl2, and postfixation with 1% OsO4 in 0.1 M s-collidine containing 0.5 mM CaCl2 and 1.0 mM MgCl2. Good preservation was also obtained using Na phosphate during prefixation and postfixation. Other combinations of buffers led to shrinkage, dilation of rough endoplasmic reticulum cisternae, disruption of membranes or loss of matrix and secretory granules. The results demonstrate that the variants of parathyroid chief cells, multinucleated syncytial cells and atrophic cells arise during fixation.

Animals↗
PubMed1986

Oral cavity and laryngeal cancers among man-made mineral fiber production workers.

From 1975 to 1984, the incidence of cancer was determined among workers employed in a French man-made mineral fiber (MMMF) production plant. The cohort, including 1 374 fully active or retired men, represented 12 793 person-years. Forty-one patients had cancer, 19 of which were in the upper respiratory and alimentary tract and five of which were lung cancers. The number of lung cancers observed did not significantly differ from that expected [standardized incidence ration (SIR) 0.7]. However the incidence of upper respiratory and alimentary tract cancers was significantly higher (SIR 2.2), especially for those in the larynx (SIR = 2.3), pharynx (SIR 1.4), and buccal cavity (SIR 3.0). The relative risk of cancers in the upper respiratory and alimentary tracts seemed to increase with the length of exposure to glass fibers and exceeded the value of 3.0 for more than 10 years of exposure. This result does not seem to be attributable to an excess of tobacco and/or alcohol consumption. No previous survey of the MMMF industry has shown such a risk, except in Italy. Thus this finding has to be confirmed.

Adult↗
PubMed1985

Ultrastructural morphometry of parathyroid cells in rats of different ages.

Parathyroid glands of newborn to 1-year-old male Sprague-Dawley rats were fixed by perfusion or by immersion, and prepared for electron microscopy. Parathyroid glands fixed by immersion exhibited parenchymal cells with variable ultrastructure, indicating that these cells were in different stages of the proposed secretory cycle in parathyroid cells. In contrast, parathyroid cells of glands fixed by perfusion were uniform in ultrastructure, suggesting that all cells were in the same stage of secretory activity. Parathyroid glands of 3-, 4-, 6-, 8- and 10-week-old rats also were fixed by perfusion and analysed by electron-microscopic morphometry. These data demonstrated an increase in cell volume and in surface area of the membrane compartments concerned with parathyroid hormone secretion: these changes were not related to variations in serum calcium concentration. Both the qualitative observations and the quantitative data do not favour the idea of a secretory cycle in rat parathyroid cells.

Aging↗
PubMed1985

Quantitative aspects of membrane behavior in rat parathyroid cells after depression or elevation of serum calcium.

The behavior of membranes concerned with parathyroid hormone secretion was studied by electron microscopic morphometry in parathyroid cells of rats with temporarily reduced serum calcium concentration resulting from phosphate ion application and in rats with elevated serum calcium concentration following vitamin D3 administration. The phosphate ion application resulted in an increase of the cell surface area and a concomitant decrease of the surface area of the Golgi complex and secretory granules within 3 hours. After 3 hours, the cell surface area decreased, whereas the surface area of the Golgi complex and the secretory granules increased, and after 12 hours, the surface area of the rough endoplasmic reticulum also increased. In the vitamin D3-treated rats the surface area of the secretory granules increased, but the cell surface area had decreased by 24, 48, and 72 hours after application. These data suggest that parathyroid cells respond to a transient depression of the serum calcium concentration by an initial centrifugal membrane shift indicating enhanced exocytosis, followed by a centripedal membrane shift indicating enhanced endocytic retrieval of the plasma membrane. Later, membrane synthesis led to an increase of the membrane compartments concerned with parathyroid hormone secretion. Elevation of the serum calcium concentration following vitamin D3 treatment resulted in reduced release of parathyroid hormone by exocytosis and enhanced retrieval of plasma membranes by endocytosis. The fate of the retrieval plasma membrane remains unclear.

Animals↗
PubMed1984

Quantitative aspects of membrane shifts in rat parathyroid cells initiated by decrease in serum calcium.

The secretory activity of parathyroid glands in rats was stimulated by decreasing the serum Ca++ concentration through constant intravenous infusion of EGTA. The morphometric analysis of the nuclear and cytoplasmic volume and of the surface area of the rough endoplasmic reticulum, Golgi complex, secretory granules and plasma membrane revealed a membrane shift from secretory granules and Golgi complex to the plasma membrane within 1 hr of calcium depression. Subsequently, between 1 and 3 hr of calcium depression, the membrane shift was from the plasma membrane to the Golgi complex. It is considered likely that these membrane shifts are related to a rise in release of parathyroid hormone by exocytosis and a subsequent increase in retrieval of plasma membrane by endocytosis--probably through the compartment of coated pits and coated and uncoated vesicles.

Animals↗
PubMed1983

The localization of fumarase and malic enzyme in muscle mitochondria of Ascaris suum.

The distribution of fumarase and malic enzyme in Ascaris suum muscle mitochondria was investigated by employing digitonin fractionation techniques. The ability of these procedures to resolve the various submitochondrial fractions (intracristal space, inner membrane, matrix and inner membrane-matrix particles) was verified by electron microscopy and the distribution of appropriate marker enzymes. From the data obtained, it is concluded that fumarase in Ascaris muscle mitochondria is located solely within the matrix compartment and is not present within the intracristal space as reported earlier by other authors (Rew and Saz (1974) J. Cell. Biol. 63, 125-135). In agreement with previous findings malic enzyme in the nematode organelle appears to be associated with both soluble compartments. The implications of these findings to the parasites' mitochondrial metabolism are discussed.

Animals↗
PubMed1982

Quantitative changes of membranes in rat parathyroid cells related to variations of serum calcium.

Parathyroid glands of rats were exposed to low, normal, or high serum calcium concentration by infusion of either ethylenglycol-bis-(2-aminoethylether)-tetraacetic acid (EGTA), NaCl, or CaCl2 for 90 minutes. Electron microscopic morphometry revealed that the cell volume remained constant, whereas the cell surface increased significantly after EGTA infusion and decreased significantly after CaCl2 infusion compared with parathyroid cells of NaCl-infused rats. The surface of the Golgi complex including the surrounding vesicles increased significantly after CaCl2 infusion. Significant changes were not obvious in the volume and surface of the nucleus or in the surface of the rough endoplasmic reticulum. These results suggest, first, that parathyroid hormone is released by exocytosis leading to increased cell surface within 90 minutes. Second, it is considered likely that plasma membrane constituents are retrieved by endocytosis and incorporated into the Golgi complex supporting the idea of membrane recycling.

Animals↗