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Biomedical subjects

M L Jones

Publications and source records attributed to M L Jones.

At least 91 records · Page 5Linked to original sources
PubMed1995

Crystal bonding--an adhesive system with a future?

The primary objective of this investigation was to evaluate the crystal bonding technique and to: (1) study the effect on crystal size, coverage, and morphology of altering the concentration of lithium sulphate in a crystal growth solution; (2) investigate the potential for reattachment of brackets, following the use of the crystal growth technique; (3) assess the deterioration of the crystal growth conditioning solution with time; (4) investigate the influence of polyacrylic acid enamel pretreatment on the bond strength subsequently achieved with the crystal growth technique; and (5) confirm that the use of crystal growth solutions to attach orthodontic brackets, results in minimal enamel surface change on debond when compared to the acid etch technique. The results of the study suggest that altering the lithium sulphate concentration of the crystal growth solution results in little alteration in the size, morphology, and coverage of crystal produced. The crystal growth technique allows reattachment of orthodontic brackets with no obvious deterioration in bond strength and the crystal growth solution shows little deterioration in performance after storage for 2 years. However, the hope that the use of the crystal growth technique might be a routine and valid alternative to the acid etch technique could not be confirmed.

Acid Etching, Dental↗
PubMed1995

Regulatory roles of tumor necrosis factor-alpha and interleukin-1 beta in monocyte chemoattractant protein-1-mediated pulmonary granuloma formation in the rat.

Intravenous infusion of particulate yeast cell wall glucan into rats results in the synchronous development of angiocentric pulmonary granulomas that are composed almost entirely of monocytes and macrophages. Previous studies indicate that locally produced monocyte chemoattractant protein-1 (MCP-1) is required for full granuloma development. Because tumor necrosis factor-alpha (TNF-alpha) and interleukin 1 (IL-1) can induce MCP-1 production in a variety of cell types, we sought to determine their potential regulatory roles in this model. A single infusion of anti-TNF-alpha antibody at the time of glucan infusion (time 0) markedly reduced MCP-1 mRNA levels at 1 and 6 hours but not at later time points; there was no effect on granuloma size or number measured at 48 hours. When multiple infusions of anti-TNF-alpha antibody were administered over a 23-hour period (0 to 23 hours), MCP-1 mRNA was reduced through 24 hours, there was a significant reduction in peak bronchoalveolar lavage fluid MCP-1 activity at 48 hours, and there were marked reductions in granuloma size and number at 48 hours. Similar results were observed in animals that received infusions of anti-IL-1 beta. Infusion of anti-IL-1 beta at time 0 resulted in moderate reductions in MCP-1 mRNA at 1 and 6 hours and had no effect on granuloma size or number measured at 48 hours. When multiple infusions of anti-IL-1 beta were administered over a 23-hour period (0 to 23 hours), MCP-1 mRNA was reduced through 24 hours, there was a moderate reduction in peak bronchoalveolar lavage fluid MCP-1 activity at 48 hours, and there were marked reductions in granuloma size and number at 48 hours. A single infusion of anti-TNF-alpha and anti-IL-1 beta together at time 0 resulted in marked reductions in whole lung MCP-1 and mRNA at 1 and 6 hours, but not at 24 hours. Multiple combined infusions of anti-TNF-alpha and anti-IL-1 beta over a 23-hour period resulted in additive reductions in MCP-1 mRNA through 24 hours, bronchoalveolar lavage fluid MCP-1 activity at 48 hours, and granuloma size and number at 48 hours. These data suggest that locally produced TNF-alpha and IL-1 beta play regulatory roles in glucan-induced pulmonary granulomatous vasculitis through the modulation of local MCP-1 production.

Animals↗
PubMed1994

Lung monocyte chemoattractant protein-1 gene expression in bleomycin-induced pulmonary fibrosis.

Recent studies indicate that monocyte chemoattractant protein-1 (MCP-1) may play an important role in pulmonary inflammation. In vitro studies show that a number of cell types are capable of producing MCP-1. In this study, MCP-1 expression in lungs of rats with bleomycin (BLM)-induced pulmonary fibrosis is examined to evaluate its cellular origin and potential role in pathogenesis. Lung fibrosis was induced in male Fisher 344 rats by endotracheal injection on day 0. On selected days after injection, lungs were harvested for in situ and Northern hybridization analyses for MCP-1 mRNA expression, immunochemical and histochemical analyses for MCP-1 protein expression, and identification of cell type. Northern analysis revealed significant elevation in lung MCP-1 mRNA expression beginning on day 3 post-BLM treatment, increasing to a peak on day 7, and then decreasing toward control levels after day 21. In situ hybridization combined with histochemical staining with chromotrope 2R indicate that most of the cells expressing MCP-1 mRNA at these time points are primarily eosinophils. A few scattered reactive fibroblasts, some mononuclear cells, epithelial cells, and cells of certain blood vessel walls also express this mRNA. Increased MCP-1 protein expression also was found to be predominantly within and adjacent to eosinophils. The eosinophils expressing this mRNA were found predominantly within areas of active fibrosis. The kinetics of increase in the number of cells expressing significant MCP-1 mRNA in lung sections paralleled that for MCP-1 mRNA expression, as assessed by Northern analysis. These results, for the first time, demonstrate that MCP-1 is up-regulated significantly in this rat animal model, and that infiltrating eosinophils represent the major cellular source for this increased MCP-1 expression.

Animals↗
PubMed1994

Requirements for L-selectin in neutrophil-mediated lung injury in rats.

L-selectin requirements in three models of acute lung injury in rats have been identified: systemic activation of complement after intravenous infusion of cobra venom factor (CVF) and intrapulmonary deposition of IgG or IgA immune complexes. In the CVF model of lung injury, treatment of rats with hamster monoclonal IgG anti-rat-L-selectin (HRL-1) induced significant neutropenia, necessitating the use of F(ab')2 fragments, which did not cause neutropenia. Treatment of rats with F(ab')2 anti-L-selectin (HRL-1) resulted in significant reductions in lung permeability and hemorrhage in the CVF model. Morphologically, this treatment abrogated adhesive interactions of neutrophils with the pulmonary vascular endothelium. In the IgG immune complex model of injury, the parameters of injury were significantly reduced as a result of treatment with HRL-1. In both models protection was associated with reductions in lung myeloperoxidase content. Treatment of rats with a F(ab')2 form of hamster monoclonal IgG non-blocking anti-L-rat selectin, HRL-2, failed to show protective effects in the CVF and IgG immune complex models of lung injury. In the IgA immune complex model of injury, which is neutrophil-independent and related to toxic products from pulmonary macrophages, no protective effects of anti-L-selectin (HRL-1) were found. Therefore, in neutrophil-dependent and oxygen radical mediated lung injury, L-selectin plays a requisite role in tissue recruitment of neutrophils. In the neutrophil-independent model of lung injury, no requirement for L-selectin appears to exist.

Animals↗
PubMed1994

An in vitro study of the effects of different crystal growth solutions on the topography of the enamel surface.

This study evaluated the effect on the topography of the enamel surface of applying various solutions based on polyacrylic acid. This base solution consisted of 50 per cent aqueous polyacrylic acid (molecular weight 5000) and concentrated sulphuric acid (98 per cent). Previously, similar solutions have been found to initiate a crystal growth on the enamel surface and have been proposed as being suitable for the attachment of orthodontic brackets via a composite resin interface. The base solution was modified by the addition of various ionic salts: the sulphates of lithium, magnesium and potassium, respectively. Human premolar teeth were then treated to a standard format and the effect on the enamel surface was examined by the use of a scanning electron microscope at x 500 and x 1500 magnification. The resultant micrographs of the specimens were presented to three independent observers who assessed the length, quality, and degree of coverage of the crystals. The solution containing potassium sulphate gave the longest crystals, whilst the greatest degree of coverage was obtained with the magnesium sulphate solution. Each solution was found to produce a consistent and recognizable morphology.

Acid Etching, Dental↗
PubMed1994

Orthodontic facebow injuries and safety equipment.

Facebows are widely used in orthodontic treatment to reinforce anchorage, and in selected cases can be very useful and effective. However, they are not without their problems. Reports of injuries with this appliance have continued to appear in the literature since 1975. This article reports the results of a preliminary survey of 23 European countries confirming 10 eye injuries and includes a review of the current literature. The safety headgears currently available are examined and their adequacy, in the light of this survey, is assessed.

Adolescent↗
PubMed1994

C5a-induced expression of P-selectin in endothelial cells.

Human umbilical vein endothelial cells have recently been shown to respond to C5a with increases in intracellular Ca2+, production of D-myo-inositol 1,4,5-triphosphate and superoxide anion generation. In the current studies, C5a had been found to cause in a time- and dose-dependent manner rapid expression of endothelial P-selectin, secretion of von Willebrand factor, and adhesiveness for human neutrophils. The effects of C5a in P-selectin expression and adhesiveness of neutrophils were similar to the effects of histamine and thrombin on endothelial cells. The adhesiveness of C5a-stimulated endothelium for neutrophils was blocked by anti-P-selectin, but not by antibodies to intercellular adhesion molecule 1, E-selectin, or CD18. A cell-based ELISA technique has confirmed upregulation of P-selectin in endothelial cells exposed to C5a. Binding of C5a to endothelial cells has been demonstrated, with molecules bound being approximately 10% of those binding to neutrophils. By a reverse transcriptase-PCR technique, endothelial cells have been shown to contain mRNA for the C5a receptor. These data suggest that C5a may be an important inflammatory mediator for the early adhesive interactions between neutrophils and endothelial cells in the acute inflammatory response.

Cell Adhesion↗
PubMed1994

A comparative study of the shear bond strengths of four different crystal growth solutions.

Previously, solutions based on polyacrylic acid have been found to initiate crystal growth on the enamel surface. Such crystals have been proposed as being suitable for the attachment of orthodontic brackets via a conventional composite interface, the advantages being improved clean-up characteristics and reduced damage to the enamel. In order to try and improve the reliability of the technique this base solution has been modified by the authors, by the addition of various ionic salts. The strength of the resultant bond was assessed for the base solution of 50 per cent polyacrylic acid and concentrated sulphuric, and for three more solutions modified by the addition of the sulphates of lithium, magnesium, and potassium, respectively. A standard acid/etch method of bracket attachment was also included for the purposes of comparison. The bond strength of each material was assessed by shear testing, performed on human extracted premolar teeth to a standard method. As might have been expected the acid/etch system proved to be the strongest method of bonding brackets. Amongst the crystal solutions, the addition of lithium sulphate provided the highest mean shear strength at 80 per cent of that for acid etch. Therefore, this latter solution provides the most potential for development in the future.

Acid Etching, Dental↗
PubMed1994

The finite element analysis of stress in the periodontal ligament when subject to vertical orthodontic forces.

In the past, vertical intrusive movement of teeth has been considered difficult and most routine clinical vertical movement of teeth has been confined to extrusion. It has been suggested that attempts at intrusion may result in an increased incidence of root resorption and also in occasional devitalization. The displacement and resulting stress fields associated with such treatment can be successfully studied using the finite element method. In the case being considered initial movements are known to be small; therefore, the assumption in the study that the material behaves linear-elastically is considered to be reasonable. This study of vertical tooth movement demonstrated that the maximum cervical margin stress in the periodontal ligament was 0.0046 N/mm2, whilst the highest apical stress was 0.00205 N/mm2 when intrusive and extrusive forces of 1 Newton were applied to the buccal surface of the crown of a tooth model. These stresses were evaluated in the light of previous studies and found to be within the suggested clinical optimum level. However, the periodontal stress distribution following orthodontic loading within this three-dimensional finite element model was found to be highly complex.

Cuspid↗
PubMed1994

Anti-ICAM-1 antibody reduces ischemic cell damage after transient middle cerebral artery occlusion in the rat.

Intercellular adhesion molecule-1 (ICAM-1) is a glycoprotein expressed on endothelial cells that facilitates leukocyte adhesion. To test the hypothesis that reduction of leukocytes in an ischemic lesion reduces ischemic brain damage, we measured the effect of administration of an anti-ICAM-1 monoclonal antibody on ischemic brain damage after transient middle cerebral artery occlusion in the rat. ICAM-1 expression increased in the ischemic lesion, and the lesion volume was significantly reduced by 41% in the anti-ICAM-1 antibody group compared with the control group (p < 0.05). Numbers of polymorphonuclear leukocytes (PMNs) were significantly reduced in the cortices of the anti-ICAM-1 antibody group compared with the control animals (p < 0.05). Our data indicate that administration of anti-ICAM-1 antibody results in a significant reduction of ischemic brain damage concomitant with a reduction of PMNs in the lesion after transient focal cerebral ischemia in the rat.

Animals↗
PubMed1994

The OSHA standard setting process: role of the occupational health nurse.

1. Occupational health nurses are the health professionals most often involved with the worker who suffers as a result of ineffective or non-existent safety and health standards. 2. Occupational health nurses are familiar with health and safety standards, but may not understand or participate in the rulemaking process used to develop them. 3. Knowing the eight basic steps of rulemaking and actively participating in the process empowers occupational health nurses to influence national policy decisions affecting the safety and health of millions of workers. 4. By actively participating in rulemaking activities, occupational health nurses also improve the quality of occupational health nursing practice and enhance the image of the nursing profession.

Guidelines as Topic↗
PubMed1994

The accuracy of computerized prediction of the soft tissue profile: a study of 25 patients treated by means of the Le Fort I osteotomy.

This study was performed to compare the soft tissue movements in facial profile predicted by a computer package with those that had actually occurred following a maxillary advancement osteotomy. The source of the material was serial lateral cephalograms for 25 consecutive patients who had received similar Le Fort I osteotomies primarily to correct an anteroposterior skeletal discrepancy. Many of the digitized points on the soft tissue profile were surprisingly well predicted by the computer package. The chin and profile changes resulting from mandibular autorotation and/or a genioplasty were generally predicted accurately. However, in some cases prediction was less consistent, particularly in the region of the nose and upper lip. In this latter group of patients, initial size, thickness, and morphology of the soft tissues appeared to be important factors to which some consideration could be given in the further refinement of this type of software.

Adolescent↗
PubMed1994

Automatic identification of surgical and orthodontic instruments.

Surgical instruments are becoming increasingly expensive and represent an important component of the costs of operating theatres. The use and processing of surgical instruments in decontamination and packaging units and in the operating theatre need to be monitored, both to improve efficiency and to allow measurement of the effectiveness of training in operative technique. Automatic identification of surgical and orthodontic instruments was therefore performed using two standard methods: the two-dimensional bar-code and matrix code. Encryption (the formulation of codes), was carried out prior to bar and matrix coding using acid-etch and laser techniques respectively. 'Reading' of the two types of code was more difficult with bar-codes because of the high reflectivity of background polished stainless steel, and only large instruments had sufficient area for bar-coding. Consistent, accurate, automatic identification of the instruments was possible with the matrix code for which a surface of only 4 sq mm is necessary. After 50 cycles of decontamination and packaging, neither code showed obvious deterioration and it was possible to read the matrix code as easily as prior to this process. Automatic instrument identification is possible using recently developed methods and could facilitate economies in the processing of instruments in health facilities and the automatic recording of instrument usage in the operating theatre.

Electronic Data Processing↗
PubMed1994

Lipopolysaccharide induces monocyte chemoattractant protein production by rat mesangial cells.

Lipopolysaccharide, a potent pro-inflammatory constituent of bacterial cell walls, is capable of promoting glomerular inflammation, by both activating circulating inflammatory cells and local interactions with renal parenchymal cells. We sought to determine whether lipopolysaccharide was capable of promoting glomerular inflammation by directly stimulating mesangial cell production of monocyte chemoattractant protein 1, a recently described cytokine capable of eliciting recruitment of mononuclear phagocytes into inflammatory foci. Northern hybridization analysis revealed dose and time-dependent induction of mRNA coding for monocyte chemoattractant protein 1 in quiescent rat mesangial cells treated with lipopolysaccharide. Lipopolysaccharide-elicited induction of monocyte chemoattractant protein mRNA was detectable after 1 hour and persisted for at least 30 hours. Media isolated from rat mesangial cell cultures stimulated by lipopolysaccharide possessed monocyte chemotactic activity that was detectable at 8 hours and peaked at 24 hours; an antimonocyte chemoattractant protein antibody blocked 87% of this chemotactic activity. We suggest that lipopolysaccharide, released from bacterial cell walls, promotes glomerular inflammation by stimulating mesangial cell production of monocyte chemoattractant protein 1.

Animals↗
PubMed1993

Involvement of platelet-endothelial cell adhesion molecule-1 in neutrophil recruitment in vivo.

During inflammation, neutrophils migrate from the vascular lumen into extravascular sites. In vitro assays have suggested that platelet-endothelial cell adhesion molecule-1 [PECAM-1 (CD31)], a member of the immunoglobulin superfamily, is required for the transmigration of neutrophils across endothelial monolayers. Antibody to human PECAM-1, which cross-reacts with rat PECAM-1, was found to block not only in vivo accumulation of rat neutrophils into the peritoneal cavity and the alveolar compartment of the lung but also neutrophil accumulation in human skin grafts transplanted onto immunodeficient mice. On the basis of these findings in three different models of inflammation, it appears that PECAM-1 is required for neutrophil transmigration in vivo and may thus be a potential therapeutic target.

Animals↗
PubMed1993

Protective effects of IL-4 and IL-10 against immune complex-induced lung injury.

Recombinant murine IL-4 and IL-10 have been used in two models of inflammatory lung injury in rats after intrapulmonary deposition of IgG or IgA immune complexes. These models have contrasting requirements for cytokines, phagocytic cells, and adhesion molecules. In these two models of lung injury, IL-4 and IL-10 were individually coinstilled into the airways with the IgG or IgA antibodies, whereas the Ag were injected intravenously. Injury was quantitated by increases in permeability (leakage of 125I-BSA) and by hemorrhage (extravasation of 51Cr-RBC). In the model of IgG immune complex-induced lung injury, IL-4 and IL-10 were each highly protective when given in nanogram amounts. These protective effects were dose dependent. IL-4 and IL-10 caused substantial reductions in lung content of myeloperoxidase and parallel reductions in neutrophil content in bronchoalveolar lavage (BAL) fluids. The protective effects of IL-4 and IL-10 were associated with profound reductions of TNF-alpha in the BAL fluids and complete inhibition in the up-regulation of pulmonary vascular ICAM-1. In the IgA immune complex model of lung injury IL-4 had no protective effects, whereas IL-10 was highly protective. These protective effects correlated with diminished retrieval of alveolar macrophages in BAL fluids. These data suggest that IL-4 and IL-10 have significant protective effects in lung inflammatory injury, presumably achieving these effects by various mechanisms.

Animals↗
PubMed1993

Inhibition of lung inflammatory reactions in rats by an anti-human IL-8 antibody.

IL-8 belongs to the family of chemotactic cytokines and may play an important role in the inflammatory response. In the current studies, a murine mAb (DM/C7) to human rIL-8 was found to have protective effects in inflammatory lung injury in rats. DM/C7 was nonreactive with the rat cytokine-induced neutrophil chemoattractant peptide. In vivo, DM/C7 blocked the glycogen-induced accumulation of neutrophils in rats and was highly protective against lung and dermal vascular injury after deposition of IgG immune complexes. The latter model of injury has recently been shown to be E-selectin dependent. The protective effects of DM/C7 correlated with reduced tissue accumulation of neutrophils, as measured by myeloperoxidase content. DM/C7 reacted with an epitope expressed by TNF-alpha-stimulated rat pulmonary artery endothelial cells and with the pulmonary vascular endothelium after intrapulmonary deposition of IgG immune complexes. In the model of IgG immune complex-induced lung injury, the protective effects of DM/C7 were abolished by prior absorption of the antibody with human rIL-8. Polyclonal antibody to cytokine-induced neutrophil chemoattractant peptide failed to protect against IgG immune complex-induced vascular injury even though this antibody blocked the in vitro chemotactic activity of cytokine-induced neutrophil chemoattractant. In the model of rapidly developing lung injury due to systemic activation of C after infusion of cobra venom factor, DM/C7 was not protective. As well, in the neutrophil-independent model of IgA immune complex-induced lung injury, treatment with DM/C7 was not protective. These data indicate that in inflammatory lung injury that is linked to E-selectin-dependent recruitment of neutrophils in rats, antibody to human IL-8 also blocks recruitment of neutrophils and thereby affords protection against lung injury. The data suggest the presence of an IL-8-like product in this model of lung injury.

Animals↗