Biomedical subjects
Publications and source records attributed to A Whyte.
Dental panoramic tomography is commonly presented to radiologists with no dental training for interpretation. An overview of the technique, basic anatomy and nomenclature and common pathology is presented with examples to show the anatomy and nomenclature, the artefacts and common pathology.
A new cause of sound and pressure induced vertigo, superior canal dehisence, is described. Auditory manifestations include hyperacusis to bone-conducted sounds and conductive hearing loss with normal acoustic reflexes. The diagnosis is reached by a directed history, documentation of upward and torsional nystagmus evoked by sound and pressure, and radiology. Acoustic reflexes and VEMP (vestibular evoked myogenic potentials) aid in the identification of patients with an apparent conductive loss with normal acoustic reflexes or have an asymptomatic dehiscense on radiology. Treatment involves avoidance of the precipitating stimuli. Surgical treatment, by resurfacing the dehiscence, is considered in patients with more severe symptoms.
The demonstration of an opaque antrum on a plain radiograph or cross-sectional imaging leads to consideration of an extensive differential diagnosis. Relevant clinical details narrow the differential and include the patient's age, signs and symptoms, a history of recent trauma, prior surgery or dental treatment. Computed tomography remains the most useful technique in coming to a specific diagnosis. Magnetic resonance imaging adds specificity in a few selected situations and is required in conjunction with CT in the staging of malignant tumours.
PURPOSE: In recent years, researchers have noted that catastrophizing predicts both self-reported and objective measures of disability in a variety of chronic pain conditions. The present study sought to examine this in a working-age amputee population experiencing phantom pain. METHOD: Participants completed a postal questionnaire incorporating measures of pain, disability and coping. A response rate of 62% resulted in 315 completed data sets being incorporated into the study. RESULTS: Utilizing the three subscales of the Sickness Impact Profile, catastrophizing uniquely predicted 11% of the variance in overall level of disability, 6% in physical disability and 13% in psychosocial disability after accounting for demographic, amputation and pain-related variables. CONCLUSION: The findings suggest that catastrophizing is a significant predictor of self-reported disability in an amputee population. This population have lifetime rehabilitation needs in that prostheses have to be remade on a regular basis. The service provided tends to focus on physical rehabilitation with the goal of providing amputees with limbs that most closely resemble the appearance and function of the intact limb. This study provides tentative support for development of an intervention that specifically targets catastrophizing.
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BACKGROUND AND OBJECTIVE: We tested the hypothesis that disturbances of the visual pathway persist following general anaesthesia, even after normal clinical discharge criteria have been met. METHODS: We performed full-field flash electroretinography in the right eye of 10 unpremedicated ASA I patients who underwent N2O/sevoflurane anaesthesia. Electroretinograms were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which postanaesthesia discharge score first exceeded 9 was also noted. Data were analysed using paired, one-tailed Student's t-test. RESULTS: Latency of the b-wave on the photopic electroretinogram was greater at each postoperative time point (30.5 +/- 0.9 and 30 +/- 1.3 ms), compared to preoperative values (29.2 +/- 0.8 ms, P < 0.001 and P = 0.04, respectively). The A-B amplitude of the b-wave was less postoperatively (220.3 +/- 52.7 and 210.3 +/- 42.7 pV) compared to values before operation (248.1 +/- 57.6 microV, P = 0.03 and P = 0.01, respectively). Oscillatory potential latencies were greater at each postoperative time point (21.4 +/- 0.5 and 20.8 +/- 0.6 ms) compared to before operation (20.4 +/- 0.4 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential amplitudes were less at the first postoperative time point (17.5 +/- 6.1 microV), compared to preoperative values (22 +/- 6.4 microV, P = 0.04). CONCLUSIONS: Postoperative electroretinogram abnormalities are consistently present in patients who have undergone N2O/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.
BACKGROUND AND OBJECTIVE: We tested the hypothesis that disturbances of the visual pathway following sevoflurane general anaesthesia (a) exist and persist even after clinical discharge criteria have been met and (b) are associated with decreased contrast sensitivity. METHODS: We performed pattern and full-field flash electroretinograms (ERG) in 10 unpremedicated ASA I patients who underwent nitrous oxide/sevoflurane anaesthesia. ERG and contrast sensitivity were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which the Post Anaesthesia Discharge Score first exceeded 9 was also noted. Data were analysed using paired, one-tailed t-tests and Pearson's correlation coefficient. RESULTS: On the full-field photopic ERG, b-wave latency was greater at each postoperative time point (31.6+/-1.1 and 30.8+/-1.1 ms) compared to preoperatively (30.1+/-1.1 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential latencies were greater on discharge from the recovery room compared with preanaesthetic values (23.1+/-3.1 vs. 22.4+/-3.3 ms, P = 0.01) and returned to baseline by 2 h after emergence from anaesthesia. Also at 2 h after emergence from anaesthesia: (a) P50 latency on the pattern ERG was greater than at baseline (81.5+/-17.9 vs. 51.15+/-22.6ms, P = 0.004); (b) N95 amplitude was less compared to preanaesthetic values (2.6+/-0.5 vs. 3.3+/-0.4 microV, P = 0.003) and (c) contrast sensitivity was less compared to baseline values (349+/-153 vs. 404+/-140, P = 0.048). A positive correlation was demonstrated between contrast sensitivity and both N95 amplitude and b-wave latency (r = 0.99 and r = -0.55 at significance levels of P < 0.005 and P < 0.05, respectively). CONCLUSIONS: Postoperative ERG abnormalities and associated decreases in contrast sensitivity are consistently present in patients who have undergone nitrous oxide/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.
The effects on the testis of open-ended vasectomy in the Wistar rat have been assessed morphometrically and evaluated statistically at 1, 4, 12, and 24 weeks after operation, and compared to those in sham-operated controls. The open-ended technique, ie, without ligation of the epididymal end of the cut ductus deferens, allowed drainage of sperm into the spermatic cord. During the period of our study, it did not affect the structure of the testis; although the germinal epithelium, basement membrane, and the stroma and cells of the interstitial space all showed variations when compared to the control group, these were not statistically significant.
In this pictorial essay we aim to illustrate the normal temporomandibular joint (TMJ) and the common abnormalities of the osseous, cartilaginous and soft tissue components. These include disc (meniscus) displacement, deformities and perforations, abnormalities of disc and condylar movement, joint effusions, synovial proliferation, condylar deformity and erosions, degenerative change and abnormal retrodiscal enhancement.
Self-neglect can be understood as the failure to engage in those activities which a given culture deems necessary to maintain a socially accepted standard of personal and household hygiene and carry out activities needed to maintain health status. Self-neglect is bound up in a discourse which equates dirt with disease and in which transgressions of self-care norms can be labelled as a medical syndrome. The notion of self-neglect as a social construction is the theoretical perspective which provides the framework for the study reported here. Judgements regarding self-neglect may be social judgements influenced by professional socialisation and cultural values. The belief that different groups of nurses may have different constructions of self-neglect will be investigated and the factors which influence these judgements will be explored in three groups of nurses. The inclusion of nursing students will allow some picture to emerge as to whether judgements develop over time or are relatively constant across the career path, albeit within the limitations of a non-longitudinal design.
The major volatile component in the paracloacal glandular secretion of the adult African dwarf crocodile (Osteolaemus tetraspis) was isolated and characterized as a 19-carbon aromatic ketone, dianeackerone (3,7-diethyl-9-phenyl-2-nonanone). This ketone is absent from the secretion of immatures. Careful examination of dianeackerone samples isolated from individual adults revealed that this ketone occurs as both the (3S, 7S) and (3S, 7R) stereoisomers, with different individuals presenting strikingly different ratios of the isomeric forms. Our initial suspicion that the stereoisomeric dianeackerones might be indicators of gender proved untenable, leaving the role of these glandular constituents a challenge for future study.
The African dwarf crocodile, Osteolaemus tetraspis (Crocodilidae, Reptilia), possesses a pair of skin glands, the paracloacal glands, the secretion of which is thought to be used to mark nest sites or attract mates. Ten aromatic steroidal esters were isolated from this secretion and characterized on the basis of NMR spectroscopic investigations, electrospray ionization-MS analyses, and chemical degradation. These esters, which account for more than 90% of the paracloacal glandular secretion, are derived from either cholesterol or cholestanol, esterified with a C-20 or C-22 acid closely related to dianeackerone, the only significant volatile compound found in this secretion.
BACKGROUND: Ligation of alpha-galactosyl epitopes on endothelial cells by naturally occurring human antibodies causes hyperacute rejection in porcine-to-human xenotransplantation. The alpha-galactosyl-specific lectin Bandeiraea simplicifolia isolectin B4 (IB4) has been reported to trigger endothelial "gap" formation and tyrosine phosphorylation of an unidentified 130-kDa protein. We have studied two 130-kDa junctional adhesion molecules, CD31 and VE-cadherin, in porcine aortic endothelial cells (PAECs) during IB4-mediated activation. The cellular distribution of these molecules, their susceptibility to tyrosine phosphorylation, and their capacity to bind IB4 or natural human antibodies have been determined. METHODS: Porcine CD31 and VE-cadherin were cloned. Recombinant proteins and monoclonal antibodies were prepared. The distribution and phosphorylation of CD31 and VE-cadherin in confluent PAECs activated with IB4 or human serum were studied by confocal microscopy and Western blotting, respectively. RESULTS: IB4 caused rapid redistribution of CD31 and VE-cadherin away from cell junctions and tyrosine-phosphorylation of CD31 but not VE-cadherin. A monoclonal antibody to CD31 also triggered tyrosine phosphorylation of this molecule, but brief exposure of PAECs to normal human serum did not. Tyrosine-phosphorylated CD31 complexed with SHP2 and other unidentified phosphoproteins. Both IB4 and natural human antibodies bound to porcine CD31 but not to VE-cadherin. Cell adhesion tests showed that porcine and human CD31 are functionally incompatible. CONCLUSIONS: Endothelial cell retraction during IB4-mediated activation of PAECs is associated with rapid loss of CD31 and VE-cadherin from cell junctions. CD31 becomes strongly tyrosine-phosphorylated and forms a cell signaling complex, which may have a significant role in the response of the xenograft vascular endothelium.
We described previously a unique cutaneous tumour in a young pig, which was characterized by several criteria as a histiocytic leiomyofibrosarcoma. The lipid-laden macrophages (histiocytes) which permeated the tumour were CD2+/CD18+/CD49d+ but MAC387 (L1 antigen) and CD15 negative. The present study compared the phenotypes of histiocytes in tumour metastases in the liver with resident liver macrophages, revealing differential expression of certain macrophage activation markers. After repeated subcutaneous passage of the tumour in athymic (nu/nu) mice, flow cytometry demonstrated a rapid loss of porcine MHC Class II, but a more prolonged expression of porcine MHC Class I, consistent with our immunohistological observations. Mouse macrophages (CD2+/F4.80+) infiltrated the later-passage tumours, suggesting that the histiocytes were not of neoplastic origin.
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We have performed experimental vasectomies in dogs in order to study effects of vas deferens ligature with close technique, on the testicular ultrastructure. We point out the existence of alterations: structural changes of the seminiferous epithelium, great extracellular spaces which are generated for the premature exfoliation of germinal cells, degeneration of the germinal shock cells, the appearance of immature germinal cells and multinucleate spermatids in every stages of the spermatogenesis, the fall of mature spermatozoid number, thickening of basal membrane, relative increase in the Sertoli's cells size as well as their phagocytic function, and existence of spermaphagos unfasted into tubular lumen. The Leydig's interstitial islets show an absolutely normal cellular and vascular configuration.
OBJECTIVE: To analyze the effects of different surgical techniques of vasectomy on the epididymal structure. METHODS: Experimental vasectomies were performed in dogs using the conventional and open-ended techniques. The animals were orchidectomized 1 to 12 months after vasectomy and the epididymal structure was analyzed. RESULTS: The epididymal structure of dogs submitted to the conventional technique showed marked ectasia, reinforced basement membrane, loss of stereocilia in the principal cells, and formation of spermatic granulomas in interstitial tissue. At 12 months the principal cells showed signs of degenerative changes. In the different time periods analyzed in the study, no changes were observed in the epididymal structure of dogs submitted to the open-ended technique. CONCLUSIONS: The changes observed in the principal cells are ascribable to the increased intraluminal pressure produced by ligation of both ends of the vas deferens (conventional technique), since no changes were found in the epididymal structure of dogs submitted to the open-ended technique, at least in the different time periods analyzed in the study.