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Biomedical subjects

D A Deporter

Publications and source records attributed to D A Deporter.

18 recordsLinked to original sources
PubMed1979

The possible role of the fibroblast in granuloma-induced bone resorption in the rat.

Granulomas were produced over the calvaria of rats by injection of a mixture of turpentine and peanut oil. The granulomas induced localised areas of bone resorption and these resorptive lesions were examined at the fine structural level. A close association was found between osteoclasts and fibroblasts at resorbing surfaces. Furthermore, fibroblasts but not osteoclasts were observed to engulf and phagocytose bone collagen fibrils. It is suggested that the fibroblast either alone or in collaboration with the osteoclast is involved in the destruction of bone collagen during chronic inflammatory disorder of bone.

Animals↗
PubMed1979

Cyclic adenosine 3', 5'-monophosphate and the mechanism of action of three common anti-inflammatory drugs.

1 The effects of indomethacin, dexamethasone and colchicine on cyclic adenosine 3', 5'-monophosphate (cyclic AMP) concentration in leucocytes during a crystal-induced pleurisy in rats were studied. 2 Each of the drugs significantly increased leucocyte cyclic AMP content within 3 h of the injection of crystals. 3 By 6 h, leucocyte cyclic AMP levels returning toward control levels and could not be sustained at the higher level by an additional administration of the respective anti-inflammatory drug.

Animals↗
PubMed1977

The early mineralization of enamel. Fine structural observations on the cellular localization of calcium with the potassium pyroantimonate technique.

The potassium pyronatimonate technique was used to study the cellular distribution of calcium during the early mineralization of enamel in rat molar tooth germs at the electron microscope level. Differing patterns of calcium distribution were observed in the ameloblast seemingly associated with the appearance of Tomes' process. In the early secretory ameloblast calcium pyroantimonate deposits were observed within the Golgi apparatus, within coated vesicles, within mitochondria and associated with the inner aspect of the cell membrane. However, with the development of Tomes' process the ameloblast no longer demonstrated these discrete deposits of calcium pyroantimonate. Instead they showed a diffuse cytoplasmic staining pattern with no preference for any particular organelle.

Ameloblasts↗
PubMed1977

The relation of cyclic AMP levels to phagocytosis and enzyme release in acute inflammation in vivo.

The effect of altering endogenous leucocyte cyclic AMP levels on phagocytosis and lysosomal enzyme release was studied in vivo. Acute pleural exudates were produced in rats using either calcium pyrophosphate dihydrate crystals or rat serum. Despite marked increases in leucocyte cyclic AMP concentration produced by injection of dibutyryl cyclic AMP and theophylline, there was no reduction in crystal phagocytosis or in enzyme discharge.

Acid Phosphatase↗
PubMed1977

Cyclic AMP and the mechanism of leucocyte lysosomal enzyme release during an immediate hypersensitivity reaction in vivo.

The pleural cavity of rats was used to study the effect of altering leucocyte cyclic AMP content on the release of B-glucuronidase activity during an immediate hypersensitivity reaction. The effect on intravenous colchicine was also studied. Despite an increase of 135 to 235% in leucocyte cyclic AMP content no decrease in B-glucuronidase release was observed. Similarly, colchicine had no effect on enzyme release. It was concluded that the cyclic nucleotides and leucocyte microtubules may have no significant role to play in the release of lysosomal enzymes during acute inflammation in vivo.

Animals↗
PubMed1977

Cyclic adenosine 3',5'-monophosphate and leucocyte chemotaxis in vivo.

1 The effect of local elevation of leucocyte cyclic adenosine 3',5'-monophosphate (cyclic AMP) content on the continued migration of leucocytes to a site of acute inflammation was studied in the pleural cavity of rats. 2 Leucocyte cyclic AMP levels were elevated by injecting with the irritant into the pleural cavity dibutyryl cyclic AMP alone or with theophylline. 3 The treatments both produced a marked reduction in leucocyte migration into a pleural reaction induced by immediate hypersensitivity, but had no effect on cell numbers in pleurisy induced either by pyrophosphate or urate crystals.

Animals↗
PubMed1976

Effects of modification of intracellularcyclic AMP levels on the imediate hypersensitivity reaction in vivo.

Experiments were performed to study the effects of agents that elevate endogenous cyclic AMP levels on the progression of a reverse passive Arthus reaction in the pleural cavity of rats. Three hours after the onset of the reaction a marked reduction in histamine release was observed which correlated well with increases in cellular cyclic AMP concentration. The results at 6 hr suggested a relationship between cyclic AMP and leucocyte PGE, the latter being reduced dramatically both in the cells and in the fluid exudate by agents that elevate cyclic AMP. It was concluded that cyclic AMP may play an important regulatory role in vivo in the release of inflammatory mediators from leucocytes.

Animals↗
PubMed1976

The role of fibroblasts in the remodeling of periodontal ligament during physiologic tooth movement.

Our findings indicate a cellular basis for the connective tissue remodeling which takes place during physiologic tooth movement. This cell is the fibroblast which is capable of synthesizing and degrading collagen simultaneously and, utilizing this ability, the orderly control of collagen remodeling within the periodontal ligament is possible. It is suggested that this cellular basis of connective remodeling will have a direct significance for orthodontic tooth movement once control mechanisms have been established.

Amino Acids↗
PubMed1975

Quantitative studies on cell-mediated immunity in the pleural cavity of guinea-pigs.

Intrapleural injection of PPD into CFA-sensitised guinea-pigs produced a reaction having many of the characteristics of classical delayed hypersensitivity. Quantitative investigations of the time course of this reaction showed that it was typified by an initial delay in the onset of increased vascular permeability, which reached its peak between 12 and 18 hr. The cellular response in the pleural cavity followed a similar pattern, attaining maximum levels between 18 and 24 hr. Mononuclear cells dominated the reaction from 12 to 48 hr. The histological appearance of the lung tissue was also studied. Treatment with Cobra venom factor, a complement-depleting agent, failed to modify this reaction. Cyclic AMP levels were assayed for both the cellular and cell-free exudates.

Animals↗
PubMed1975

Pharmacological mediators of various immunological and non-immunological inflammatory reactions produced in the pleural cavity.

Intrapleural exudates have been produced in rats and guinea-pigs using calcium pyrophosphate, cell mediated immunity, reversed passive Arthus reaction and carrageenan. The intracellular concentration of various pharmacological mediators has been measured at different times during the evolution of these inflammatory responses. These have been correlated with volume of exudate and cellular migration. The significance of these findings has been discussed and the possible application to the search for new anti-inflammatory agents and their use in diagnostic procedures.

Animals↗
PubMed1975

Calcium pyrophosphate-induced pleurisy in rats: a new model of acute inflammation.

A model is described of acute inflammation in the pleural cavity of rats using calcium pyrophosphate as the irritant. This model would seem to simulate the pseudogout syndrome. It has been shown to be acute in onset, dominated by polymorphonuclear cells, complement independent. The advantage of the model is that volume of exudate, numbers and types of cells may be quantitated. Prostaglandins and cyclic AMP have been measured in the migrating cells. The significance of these findings has been discussed.

Animals↗
PubMed1975

A model for the quantitative study of Arthus (immunologic) hypersensitivity in rats.

A model of reverse passive Arthus (RPA) reaction in the pleural cavity of rats is described. The time course of development of exudate and migration of cells has been examined. It has been found to be complement dependent and dominated by polymorphonuclear cells. The reaction reaches a peak around 6 hours after challenge. Cyclic AMP levels have been measured both intracellularly and extracellularly and have been found to persist at high levels after the waning of the reaction.

Animals↗
PubMedDate not supplied

Microtubules, cyclic AMP and lysosomal enzyme release. A review.

The importance of microtubules and cyclic AMP in the control of lysosomal enzyme release from polymorphonuclear leukocytes is questioned. The article is a short review of pertinent literature designed to stimulate further research into this important mechanism of inflammation.

Animals↗