Back to the future: cognitive ergonomics six years on.
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Cognition↗
Biomedical subjects
P Barber
Publications and source records attributed to P Barber.
High dose rate endobronchial brachytherapy for the treatment of lung cancer: current status and indications.
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Brachytherapy↗
Ultrastructural finding of vascular degeneration in fibrodysplasia ossificans progressiva (FOP).
The masseter and temporalis muscles were investigated ultrastructurally in 2 patients having fibrodysplasia ossificans progressiva (FOP). Results showed atrophy and necrosis of muscle fibres. Both cases contained cartilage which was calcified in the second case and was associated with degenerating chondrocytes. The blood vessels showed various changes, with haematoma formation and large fibrin deposits. Some of the fibrin deposits seen in the second case were surrounded with cartilage. This suggests that the cartilage probably forms as a reaction to an old haemorrhage. It is possible that the effect of the mutant gene found in FOP is on blood vessels rather than the normal regulatory mechanisms of the inducible osteogenic precursor cells. These degenerating blood vessels often result in haemorrhage and fibrin deposits; the fibrosis, cartilage or bone formation are probably secondary changes. Amianthoid fibres found in the tendon of the temporalis muscles of the second case, together with the other changes of fibrosis and cartilage formation, account for the severe restricted mouth opening suffered by these patients.
Adolescent↗
Phylogeny of human intestinal spirochaetes inferred from 16S rDNA sequence comparisons.
The sequence of 1383 nucleotides of the DNA encoding 16S rDNA was determined for strains of human intestinal spirochaetes, comprising an unnamed isolate and "Brachyspira aalborgi" NCTC 11492. A phylogenetic tree was inferred from aligned sequence comparisons between the intestinal spirochaetes, representatives of the Spirochaetales and Escherichia coli. The type strain of Brachyspira aalborgi, though related to the Serpulina spp. at approx. 96.5% sequence similarity was distinct and separated from the unnamed human intestinal isolate, HIS Oman, N26. The latter formed a separated and novel lineage that bisected the Spirochaetales.
DNA, Ribosomal↗
Intraventricular malignant meningioma in a 6-year-old child.
The case of a malignant intraventricular meningioma in a 6-year-old child is reported. He presented with symptoms of raised intracranial pressure and computed tomography scan revealed an enhancing tumor at the region of the septum pellucidum. After surgical excision, histology showed appearances of meningioma with atypical features indicating malignant behavior.
Cerebral Ventricle Neoplasms↗
Effect of video frame rate on subjects' ability to shadow one of two competing verbal passages.
In a study addressing future use of video-telephone systems, the ability of 52 young adults with normal hearing to shadow verbal passages was assessed when they could both hear and observe the speaker. This performance was compared to performance in an audio-alone condition. The passages were presented against an irrelevant background message. Effects of varying the video frame rate (i.e., the rate at which frames were sampled) were examined, using rates of 8.3, 12.5, 16.7, and 25 Hz. The presence of the visual image of the relevant speaker always improved performance when compared with a baseline audio-alone condition. The motion of the speaker's face may generally support the focusing of attention on the target message. However, effects of video frame rate were also apparent, suggesting that specific visual cues became available as the temporal resolution improved. When frame rates of 8.3 Hz and the maximum available rate of 25 Hz were compared, shadowing performance was significantly better across the subject group at the higher frame rate. The comparison of frame rates of 12.5 and 25 Hz did not show reliably improved performance across the whole subject group at 25 Hz, although a small number of subjects seemed to benefit. This suggests there may be some differences in the visual cues used by subjects and consequent differences in the way individuals perform under different frame rates. Performance at 16.7 and 25 Hz did not differ, and this is consistent with previous research that tested people with hearing loss.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Bone resorbing activity of surface-associated material from Actinobacillus actinomycetemcomitans and Eikenella corrodens.
The results of this study demonstrate that saline extracted surface-associated material (SAM) of Actinobacillus actinomycetemcomitans and Eikenella corrodens stimulates bone resorption at picomolar concentrations. Various inhibitors of known osteolytic mediators--indomethacin, interleukin-1 receptor antagonist (IL-1ra) and a neutralising antibody to murine tumour necrosis factor (TNF) alpha--were tested to determine the mechanism of action of these SAMs. Bone resorption induced by SAM from E. corrodens was slightly inhibited by indomethacin and almost completely inhibited by blocking the action of TNF alpha; that from A. actinomycetemcomitans was not significantly affected by either of these inhibitors.
Aggregatibacter actinomycetemcomitans↗
Central neurocytoma of thalamic origin.
Central neurocytoma is a rare benign tumour of neuronal origin that has only recently been described. The majority of previously reported cases have originated from the septum pellucidum and the walls of the lateral ventricles. We describe a case of central neurocytoma arising from the thalamus. This site of origin has not been previously described. A review of the literature and discussion of the management follow.
Adult↗
Proposed mechanism of pulmonary gas trapping (PGT) following intravenous perfluorocarbon emulsion administration.
PURPOSE: To investigate various hypotheses and identify the most likely mechanism preventing the complete collapse of test animal lungs at sacrifice subsequent to intravenous injection of certain perfluorocarbon emulsions. PROTOCOL: Literature data were reviewed, experimental data were extracted from completed studies and new data were generated in an attempt to delineate reasons why, in certain animals, lungs fail to collapse normally at necropsy if previously injected with certain perfluorocarbon emulsions. The proposed hypothesis involved gas osmosis through endogenous pulmonary surfactant-liquid bridges (micro-bubbles). RESULTS: The observed effect of incomplete lung collapse upon necropsy was found to correlate with perfluorocarbon vapor pressure. Results indicated that failure to collapse could be attributed to the formation of intra-alveolar micro-bubbles induced by the normal pulmonary elimination of perfluorocarbon vapor. These micro-bubbles result in a phenomenon which could be characterized by the term, pulmonary gas trapping. Reduction of the perfluorocarbon concentration gradient across the bubble films by exposure to a perfluorocarbon vapor-containing atmosphere was found to reduce the effect in-vivo and prevent gas osmosis bubble growth in-vitro. CONCLUSION: Experimental observations are consistent with the proposed theory of perfluorocarbon-related gas osmosis through micro-bubbles that prevent complete lung collapse as observed upon opening the thoracic cavity of test animals.
Animals↗
P53 overexpression and Epstein-Barr virus infection in undifferentiated and squamous cell nasopharyngeal carcinomas.
We have analysed 22 nasopharyngeal carcinomas (NPCs) for expression of the small nuclear Epstein-Barr virus (EBV)-encoded RNAs (EBERs) and for immunohistologically detectable overexpression of p53. In situ hybridization demonstrated expression of the EBERs in 13 undifferentiated NPCs while nine squamous cell NPCs were EBER-negative. These results therefore confirm our previous DNA-DNA in situ hybridization studies and demonstrate that in the nasopharynx EBV is exclusively associated with undifferentiated but not with squamous cell carcinomas. p53 overexpression was demonstrated by immunohistology in 5 of 9 squamous cell NPCs and in 9 of 13 undifferentiated NPCs. Thus, there appears to be no correlation of p53 overexpression with EBV infection. These results are unexpected in the light of previous studies demonstrating that the p53 gene in primary undifferentiated NPC is consistently in the wild-type configuration. By contrast, analyses of squamous cell carcinomas of the head and neck have demonstrated that p53 overexpression in these cases is the result of p53 gene mutation. Whilst more detailed genetic analysis is required, our results suggest that mechanisms other than mutation of the p53 gene may be responsible for the stabilization of the protein in cases of undifferentiated NPC. It is tempting to speculate that an EBV-encoded protein may be involved.
Carcinoma↗
Biological activities of surface-associated material from Porphyromonas gingivalis.
Surface-associated material (SAM) from Porphyromonas gingivalis was tested for in vitro biological activities that may be relevant to the pathogenesis of chronic periodontitis. SAM was found to stimulate bone resorption at a concentration of 1.0 microgram/ml and this was inhibited by indomethacin, interleukin-1 receptor antagonist protein and anti-tumour necrosis factor antibody. At a concentration of 10 ng/ml, the SAM inhibited DNA and collagen synthesis in osteoblasts and murine calvaria and DNA synthesis in fibroblasts, monocytes and epidermal cells. Therefore, easily solubilised surface components from P. gingivalis could play a role in the pathogenesis of chronic periodontitis if these activities operate in vivo.
Animals↗
Ultrastructural finding of vascular degeneration in myositis ossificans circumscripta (fibrodysplasia ossificans).
A case of myositis ossificans circumscripta (fibrodysplasia ossificans) of the masseter muscle has been studied ultrastructurally. It showed atrophy of muscle fibres with deranged myofilaments, adjacent to dense fibrous tissue, osteoid and bone. A large number of the cells found in the dense fibrous tissue showed vacuolation and separation of membrane bound vesicles similar to matrix vesicles released by chondroblasts and osteoblasts during calcification. It is possible that, as in normal calcification of bone, these vesicles are responsible for initiating calcification in the ectopic bone found in the present condition. It was also shown that most of the blood vessel found in the blocks examined exhibited various degrees of degenerative changes. The finding of arterial occlusion together with capillary degeneration suggests that the main changes in myositis ossificans circumscripta may be those affecting blood vessels leading to ischaemic muscle atrophy. The fibrosis and ossification that follow are probably secondary changes.
Adult↗
Ultrastructure and histochemistry of the dental cuticle in adult periodontitis.
This study examined the dental cuticle (DC) at the interface with cementum surface, as well as its relationship to the overlying subgingival plaque (SP), the so-called plaque-free zone (PFZ), the junctional epithelium (JE), and the coronal fibers of the residual periodontal ligament (PL) by transmission electron microscopy (TEM) and histochemistry. Material comprised of 41 extracted, adult periodontitis-affected teeth (AP). Following extraction, 20 teeth were fixed in 3% glutaraldehyde in 0.1M sodium cacodylate, post-fixed in 1% osmium tetroxide, embedded in araldite, decalcified in EDTA, re-embedded in araldite, and sectioned. En bloc histochemistry was undertaken on the remaining 21 teeth, using ruthenium red, alcian blue-lanthanum nitrate, or safranin-O, and processed as above. Results show that the DC covered the cementum surface from the SP to the JE, and formed an interface with these structures. No DC was observed at the interface with PL. Morphological variations in DC surface were observed at the interface with the SP and at the so-called PFZ where bacteria were always in close contact with or surrounded by the DC. At the interface with JE, the DC appeared homogeneous, although layers varying in electron density were distinguishable. Teeth treated histochemically revealed a positive reaction of DC and bacteria to the three methods, suggesting the presence of anionic polymers including glycoproteins in the DC. It was concluded that on adult periodontitis affected teeth, the DC always covers exposed cementum and may mediate bacterial adhesion, and adsorb components from the periodontal pocket.
Adult↗
Localization of renal 11 beta-dehydrogenase by in situ hybridization: autocrine not paracrine protector of the mineralocorticoid receptor.
In the kidney, 11 beta-dehydrogenase (11 beta-DH) converts the active steroid cortisol to inactive cortisone (corticosterone to 11-dehydrocorticosterone in the rat). In man, congenital and acquired deficiency of 11 beta-dehydrogenase are rare causes of hypertension in which cortisol acts as a potent mineralocorticoid. Observations from these clinical studies indicate that 11 beta-DH conveys specificity for the mineralocorticoid receptor in distal tubules and collecting ducts. However, while some studies do indicate 11 beta-DH activity in rat distal tubules and collecting ducts, immunohistochemical studies localize 11 beta-DH only to proximal tubules. to resolve this dilemma, we have performed in situ hybridization localization of 11 beta-DH mRNA in rat kidney tissue using 35S-labeled sense and antisense cRNA probes to rat 11 beta-DH. In contrast to our immunohistochemical studies in which 11 beta-DH protein was localized predominantly to proximal tubules in the inner cortex, 11 beta-DH mRNA was expressed in tubules in both the inner and outer cortex, most probably proximal and distal tubules, and in collecting ducts extending across the corticomedullary junction to the papillary tip. Weak hybridization was also seen in glomeruli, but no hybridization to the sense 11 beta-DH cRNA or to sections pretreated with RNase-A was observed. We conclude that renal 11 beta-DH is suitably located to prevent access of glucocorticoid to the MR in an autocrine and not a paracrine fashion. 11 beta-DH in proximal tubules may protect the glucocorticoid receptor.
11-beta-Hydroxysteroid Dehydrogenases↗
"Kyphosis with lung tissue expansion".
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Animals↗
A case report of chronic neutropenia: clinical and ultrastructural findings.
This case report of severe periodontitis concerns a young male patient with chronic idiopathic neutropenia seen between 1981 and 1983 by the School of Dental Medicine of Geneva and from 1984 to 1988 by the Eastman Dental Hospital of London. The patient was maintained by intermittent systemic antibiotics, subgingival chlorhexidine irrigation, conventional debridement, brushing, and wire-mesh and composite splinting of loose teeth. After leaving school, at the patient's express wish, the extreme downhill pattern of the periodontitis resulted in removal of affected teeth and overdenture construction. The extracted teeth and associated soft tissues were examined for relevant plaque and host response features. The intact morphotypes associated with the advancing front of the lesion were invariably Gram-negative or positive coccoid cells, or less commonly short rods, as in all documented forms of periodotitis. Connective tissue destruction was associated with a leucocyte accumulation comprising mainly polymorphonuclear neutrophils (PMN) and plasma cells. Both were observed degenerated more deeply than in routine adult periodontitis, including PMN lysosome loss and lymphocyte maturation within peripheral blood vessels. Only in one instance, one part of the superficial connective tissue of one block contained bacteria. It was concluded that the features of plaque and the lesion suggest a typical first line of defence response as in other forms of periodontitis. From the consideration of the 10 years clinical history of the patient, it is clear that non-surgical management is possible even in extreme cases, without any compromise of the patient's oral or systemic health, and in accord with the patient's wishes.
Adolescent↗
Degenerative changes in masseter and temporalis muscles in limited mouth opening and TMJ ankylosis.
The masseter and temporalis muscles were studied ultrastructurally in eight cases suffering from restricted mouth opening and TMJ ankylosis. The changes varied from slight degeneration of muscle fibers, such as accumulation of lipid or lipofuscin deposits, Z-band streaming and derangement of myofilaments, in one case to moderate or severe changes of muscle atrophy and necrosis in the remaining seven cases. Nemaline bodies were also observed in one of these seven cases. In addition to these muscle changes neural degeneration especially of myelinated nerves were found in three of the cases studied. The present findings showed that in spite of the diversity of the underlying factors affecting the joint, there was many similarities in the changes observed within the muscle. It is postulated that these degenerative muscle changes probably play an important role in restricted mouth opening and TMJ ankylosis, and that some of these muscle pathology may be the result of neural involvement.
Actin Cytoskeleton↗