Search PubMed⌕ Search

Biomedical subjects

P Barber

Publications and source records attributed to P Barber.

At least 55 records · Page 3Linked to original sources
PubMed1990

The plasma cell at the advancing front of the lesion in chronic periodontitis.

This study analyses the ultrastructure of the plasma cell population of periodontitis-affected soft tissue close to the advancing front of interdental lesions. Biopsies from 20 patients and 3 control volunteers were examined: 5 with treated adult periodontitis (AP), 5 with untreated AP, 5 with treated juvenile or post-juvenile periodontitis (JP) and 5 with untreated JP. Plasma cell (PC) counts increased significantly (p less than 0.05) with lesion severity. They were absent from epithelium and sparse in the clinically healthy control specimens. Degenerate PC tended to be more numerous within JP tissue but differences were not significant (p greater than 0.05) when compared to AP. Intact plasma cells were never seen within JP superficial connective tissue. Russell bodies were small and few in number. The presence of degenerated plasma cells indicated normal formation and release of immunoglobulins within the tissues of AP and JP. Increased counts of degenerate PC and tissue destruction in JP suggested a correlation, possibly attributable to anti-collagen antibody secretion.

Adolescent↗
PubMed1989

Preparing teachers for the performance and evaluation of gaming-simulation in experiential learning climates.

Gaming-simulation exercises have become an established teaching strategy for nursing education. This paper suggests that nurse educators must now attempt to evaluate their effect on learning. Problems of evaluation are discussed and alternative approaches critically considered. The dominant 'classical' approach is rejected in favour of 'illuminative' evaluation and the approach of 'new paradigm research'. Nurse teachers are encouraged to apply the principles of therapeutic community practice and 'gestalt awareness' to the learning environment to enhance gains from experiential approaches. Finally the need to prepare teachers is examined. It is suggested that personal and interpersonal sensitivity, plus the ability to meaningfully facilitate groupwork are necessary prerequisites for effective gaming-simulation and its qualitative evaluation.

Education, Nursing↗
PubMed1989

[Aspects of distribution of plasma cells at the advancing front of the lesion in chronic periodontitis: a quantitative ultrastructural study].

The aim of this study was to compare the distribution of plasma cells within the soft tissue walls of interdental deep pockets from patients with adult (AP) and juvenile/post-juvenile (JP/PJP) periodontitis. Biopsies from 20 patients and 3 control volunteers were examined: 5 with treated AP, 5 with untreated AP, 5 with treated JP/PJP and 5 with untreated JP/PJP. No plasma cells were seen within the epithelium from any of the biopsies examined, and they were very sparse within the connective tissue from the control specimens. In all the pathological specimens examined there was marked tissue destruction. The percentage density of plasma cells tended to be statistically significantly higher in JP/PJP than in AP, and in untreated than in treated lesions. The statistical analysis showed also that plasma cells were more abundant in a layer deep to the neutrophils lining the basement membrane. Plasma cells were also more abundant in areas of extensive histological inflammation. The plasma cells were often degenerate and such degeneration appeared more evident in JP/PJP and in areas of connective tissue devoid of vascular tissue. These findings appear to indicate an association between increase of collagen destruction and increase in plasma cell percentage density. This may relate in turn to an increase in penetration and/or virulence of components of the subgingival plaque following an increase in tissue permeability. The scarcity of Russell bodies within the plasma cells would suggest that immunoglobulin production and secretion are normal.

Adult↗
PubMed1988

Ultrastructure of the periodontal lesion in a case of Papillon-Lefèvre syndrome (PLS).

In this study, 11 permanent teeth and their associated soft tissues from an 11-year-old boy with PLS were examined. Plaque, cementum and periodontal tissues were examined by scanning (SEM) and transmission electron microscopy (TEM). Except for depressed lymphocyte transformation, there were no abnormal haematological data. Local findings included abnormally thin cementum, extensive destruction of the periodontal ligament were still attached to the root, and severe inflammation of the soft tissues. Few bacteria were found in any of the soft tissue layers. The apical border plaque was restricted to gram- cocci and rods. The features observed in this case of PLS may indicate primary defects of cementum or ligament attachment, or disruption of fibroblast and cementoblast function due to the rapid advance of the disease process. Lack of bacterial invasion in the pocket soft tissue casts doubt on its involvement in the present case of severe periodontitis. The restricted range of morphotypes observed suggests a limited range of associated organisms. Further research is required to clarify the rôle of the host response and to identify the organisms involved.

Bacteria↗
PubMed1987

Bacterial penetration of pocket soft tissues in chronic adult and juvenile periodontitis cases. An ultrastructural study.

This study investigates bacterial invasion of the soft tissue walls of deep pockets from cases with adult (AP) and juvenile periodontitis (JP). Transmission electron microscopy was used to examine pocket soft tissue walls removed from extracted teeth from 5 patients with AP and 2 patients with JP. Bacteria were sparse throughout the epithelium and connective tissue, regardless of the level of tissue breakdown. However many inflammatory cells were seen, and these did appear to be located in regions of marked collagen loss. Accumulations of large numbers of bacteria were extremely rare and found only on the epithelial surface or in artefactual spaces within the deeper tissues. The findings indicate that the tissue destruction associated with periodontitis is not directly related to bacterial invasion. The sparse organisms within the pocket tissues probably result from passive entry rather than an invasive action. Under these circumstances, it would seem reasonable to suggest that bacterial metabolic products rather than the micro-organisms themselves penetrate the tissues in periodontitis.

Adult↗
PubMed1987

Mast cells containing melanin granules in sublingual keratosis.

In an ultrastructural study of 3 biopsies taken from the floor of the mouth of 2 patients suffering from sublingual keratosis, it was found that some of the mast cells appearing within the epithelium and connective tissue contained melanin granules which were found to be positive with Masson Fontana stain for melanin. These cells showed all the characteristic features of mast cells and not macrophages. The present results suggest that mast cells have phagocytosed melanin granules and therefore support those views suggesting that mast cells are capable of phagocytosis. They also suggest that not all the cells containing melanin granules and appearing in the lamina propria are the conventional melanophages but some of these may be mast cells.

Adult↗
PubMed1986

Amianthoid fibres in muscle tissue associated with temporomandibular joint ankylosis.

The masseter and temporalis muscles were studied ultrastructurally in 3 patients having extra and intra-articular ankylosis of the TMJ. Amianthoid fibres (thick collagen fibres) varying from 280-430 nm in diameter were found in the connective tissue of both muscles. These fibres appeared to form by fusion of collagen fibrils of normal thickness rather than representing an active dynamic process. The presence of amianthoid fibres in these muscles may account for the restricted mouth opening associated with TMJ ankylosis and could be of some value in future management of this condition.

Adult↗
PubMed1983

Effect of 5-hydroxydopamine on the large dense-cored vesicles in the axon terminals of the myenteric ganglia of the guinea-pig stomach.

Quantitative ultrastructural analysis revealed that the large dense-cored vesicles in the axon terminals in the myenteric ganglia of the guinea-pig stomach tend to be concentrated towards the ends of the terminals. In guinea-pigs treated with 50 mg/kg 5-hydroxydopamine, diameters of the vesicles were increased and their distribution in the terminals was altered. Treatment with reserpine prior to 5-hydroxydopamine increased the proportion of large dense-cored vesicles and decreased the overall number of vesicles in the terminals. The diameter of the vesicles was increased both in the terminal profiles and in the non-terminal segments of the axons. These observations are consistent with the view that uptake of 5-hydroxydopamine into small vesicles is followed by their transformation into large dense-cored vesicles.

Animals↗
PubMed1983

Degeneration and phagocytosis of smooth muscle cells in the neonatal rat ureter.

It was shown by ultrastructural investigation that, during the early stages of postnatal development of the rat ureter, some of the cells of the muscle coat undergo degeneration. These cells were rapidly eliminated by phagocytosis, mainly by other muscle cells. Following their incorporation into other muscle cells, the cells gradually became transformed into heterogeneous electron-dense bodies with the features of heterophagosomes.

Animals↗
PubMed1982

Distribution and diameter of large dense-cored vesicles in axon terminals in the myenteric ganglia of the mouse and hamster stomach.

The distribution and diameter of the large dense-cored vesicles in axon terminals in the myenteric ganglia of the mouse and hamster stomach were analyzed in electron micrographs of groups of 150 terminal profiles. In the mouse, the vesicles were proportionately more numerous and larger than in the hamster; they were also larger in terminal profiles containing more than 20% of the vesicles. There was no evidence of bimodality of the distribution curve of the proportion of large dense-cored vesicles/profile in either animal. The presence of a significant degree of skew of the distribution curves was indicative of uneven distribution of the vesicles in the terminals, and the occurrence of a significant inverse correlation between the proportion of large dense-cored vesicles/profile and both the diameter of the profiles and the total number of vesicles/profile was in agreement with subjective evidence of a tendency towards accumulation of the vesicles at the ends of the terminals.

Animals↗
PubMed1982

Ease of identifying words degraded by visual noise.

A technique is described for investigating word recognition involving the superimposition of 'noise' on the visual target word. For this task a word is printed in the form of letters made up of separate elements; noise consists of additional elements which serve to reduce the ease whereby the words may be recognized, and a threshold-like measure can be obtained in terms of the amount of noise. A word frequency effect was obtained for the noise task, and for words presented tachistoscopically but in conventional typography. For the tachistoscope task, however, the frequency effect depended on the method of presentation. A second study showed no effect of inspection interval on performance on the noise task. A word-frequency effect was also found in a third experiment with tachistoscopic exposure of the noise task stimuli in undegraded form. The question of whether common processes are drawn on by tasks entailing different ways of varying ease of recognition is addressed, and the suitability of different tasks for word recognition research is discussed.

Adult↗