Biomedical subjects
D Weedon
Publications and source records attributed to D Weedon.
Human subcutaneous pythiosis.
Two cases of subcutaneous infection caused by the primitive aquatic hyphal organism Pythium are described. Pythium is an important pathogen of horses in the U.S.A. and Australia. Cases of human subcutaneous pythiosis have been cited in the literature, but clinical and histopathological features have not been described previously. Both cases occurred in young immunocompetent males in the periorbital region and showed rapid growth, clinically mimicking a tumor and requiring operative biopsy. In both cases there was a history of exposure to either swampy water or horses. The tissue reaction was distinctive, closely resembling that seen in equine pythiosis, comprising well-defined granular eosinophilic islands bordered by macrophages, multinucleate giant cells, fibrosis and numerous eosinophils. Hyphae were well demonstrated with the Grocott stain but only poorly with the PAS method. Identity of the organisms was confirmed with an immunoperoxidase technique employing a polyclonal antiserum to Pythium. Both patients responded well to amphotericin B.
Diagnosis of skin cancer in the general population: clinical accuracy in the Nambour survey.
The accuracy and validity of diagnoses of skin cancer that were made by experienced dermatologists in a Queensland community survey have been investigated. Histological examination confirmed 54% of 100 clinical diagnoses of basal-cell carcinoma, squamous-cell carcinoma or intraepidermal carcinoma. Clinical accuracy was higher for basal-cell carcinoma (59%) than for squamous-cell carcinoma (39%) or intraepidermal carcinoma (38%). Such levels of diagnostic accuracy are to be expected when an unselected population is surveyed because of the relatively low prevalence of skin cancer compared with that in the patient population of a specialist practice. This reduction in diagnostic accuracy is unrelated to clinical skills, and should be borne in mind when conducting any skin-cancer screening programme in the general community.
Replacement of excised segments of proximal ureters by tubularised bladder grafts vascularised by previously established omental pedicles.
This article reports the final study of experiments in which autologous bladder grafts have been used to replace excised segments of ureters in dogs. The technique described involves the use of bladder grafts on previously established omental pedicles as replacements for proximal ureters. Grafts were tubularised over silastic stents, then completely covered with secondary wrappings of omentum. Operated upper tracts were compared to control sides up to 12 months, then, at one year, intravenous urography was repeated at which time inspection was made of operated upper tracts (and contralateral controls) using an image intensifier prior to recording renal pelvic pressure responses to increasing perfusion rates and, finally, pathological examination. Only two of 14 upper tracts with pedicle grafts were failures radiologically and no upper tract was obstructed urodynamically. This approach is recommended for consideration as a treatment option in managing longitudinal defects in ureters in humans.
Eccrine syringofibroadenoma versus acrosyringeal nevus.
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Acro-angiodermatitis. A simulant of Kaposi's sarcoma.
Acro-angiodermatitis, usually related to venous insufficiency of the lower limbs, may simulate some of the features of Kaposi's sarcoma, both to the clinician and the dermatopathologist. With the increasing incidence of Kaposi's sarcoma related to the acquired immune deficiency syndrome (AIDS), there is a greater awareness of Kaposi's sarcoma than the benign simulant. Against this background, there is a danger that acro-angiodermatitis will be misdiagnosed as Kaposi's sarcoma.
Chronic relapsing experimental autoimmune encephalomyelitis. Transient presence in blood of lymphocytes sensitised to encephalitogen at onset of inflammatory relapses.
Juvenile guinea pigs were immunised with homologous spinal cord and monitored daily over a 6-month period for neurological signs of chronic relapsing experimental autoimmune encephalomyelitis (CREAE). At various times animals were killed, numbers of leucocytes in their cerebrospinal fluid (CSF) quantified, and in vitro proliferative responses of blood lymphocytes to myelin basic protein (MBP) and its encephalitogenic nonapeptide (NP) determined. After recovering from initial acute clinical signs, animals suffered at least two major spontaneous relapses separated by remission periods of 4-5 weeks mean duration. In the early chronic phase, 5-12 weeks post-immunisation (pi), 63% of the animals recovered fully from relapses, whereas relatively irreversible neurological deficits predominated in the late chronic phase. During the acute and chronic phases, there was a highly significant correlation between clinical severity and CSF pleocytosis only in animals killed within 24 h of onset of a clinical exacerbation associated with more than 100 leucocytes/microliter of CSF. Guinea pigs with this degree of CSF pleocytosis were defined as suffering an inflammatory relapse. Blood lymphocytes responsive to MBP and NP were detected only in animals killed at the onset of clinical signs of either the acute or an inflammatory relapse. This dynamic relationship suggests that migration of encephalitogen-responsive lymphocytes via the blood to the central nervous system could produce certain relapses in CREAE. However, the relative paucity of CSF leucocytes in most animals killed during relapses between 15-26 weeks pi suggests that other factors may elicit neurological exacerbations in the late chronic phase.
Chronic experimental autoimmune encephalomyelitis. Circulating autoantibodies bind predominantly determinants expressed by complexes of basic protein and lipids of myelin.
Chronic relapsing experimental autoimmune encephalomyelitis (CREAE) was induced by immunising juvenile strain 13 guinea pigs with homologous spinal cord tissue in adjuvant. Thirteen animals were killed in the early chronic (5-12 weeks post immunisation) and 8 in the late chronic phase (after 15 weeks pi). Plasma titres of antibodies to an isolated myelin preparation were determined by enzyme linked immunoassay. Elevated titres of these antibodies were detected between 5-26 weeks pi, varied by 10-fold between different individuals, and had no direct relationship to clinical status or time pi. Of 20 CREAE plasma with anti-myelin immunoglobulins (Igs), only 3 contained substantial amounts of antibodies to myelin lipid and these were all from animals in the late chronic phase. By contrast 15/20 of the samples contained antibodies which appeared to require lipid-protein interactions for optimal binding to antigens in isolated myelin. There was a close correlation between plasma titres of antibodies to isolated myelin and to purified myelin basic protein (MBP). Even in samples with a moderately high lipid requirement for binding to isolated myelin, purified MBP could inhibit at least 50% of the binding. These observations suggest that MBP-lipid complexes are dominant immunogens in CREAE. Gross inflammation and myelin loss in spinal cords from these CREAE guinea pigs were determined by light microscopy. Substantial inflammation was apparent in some animals between 7 and 26 weeks pi. The most severe myelin loss was observed in late chronic phase animals having plasma anti-myelin Igs with a variety of specificities. The data suggest that circulating antibodies to myelin lipids or MBP-lipid complexes could contribute to demyelination in CREAE but their titres do not correlate with the extent of this process.
Papular acantholytic dyskeratosis of vulva.
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Mental illness in medical students. A problem the profession must face.
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Melanoma and other melanocytic skin lesions.
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Conception, birth, and growth of the Australian Dermatopathology Society.
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The recognition of early stages of catagen.
Several criteria for recognition of follicles in catagen have been advanced, namely, loss of metachromasia in the hair papilla, subsidence of mitotic activity there, retraction of the lower portion of the follicle, and thickening and corrugation of the fibrous root sheath. The presence of scattered apoptotic cells in the outer root sheath is an additional marker of early catagen.
Replacement of ureteric segments by intubated neo-ureterotomies (modified Davis technique) using autologous bladder and omentum in dogs.
In 14 dogs, using a modified Davis technique, excised segments of ureters were replaced by free, partial-thickness bladder grafts vascularised by omentum. Eight of the 14 dogs had satisfactory radiological appearances of the operated upper tracts at 12 months, and 9 of the 14 were unobstructed urodynamically at this time. Graft segments did not appear to contract. Urothelial and smooth muscle regeneration was observed.
Eccrine tumors: a selective review.
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Spongiotic changes in melanocytic nevi.
We report eight patients in whom one or more pigmented melanocytic nevi developed a halo of inflammation characterized histologically by spongiotic dermatitis. This change was not related to involution of any of them. One of these pigmented lesions was thought clinically to be a malignant melanoma.