Biomedical subjects
D Weedon
Publications and source records attributed to D Weedon.
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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Amyloid in basal cell carcinomas.
Stromal or intratumour deposits of amyloid were found in thirty of forty-six randomly selected basal cell carcinomas. Amyloid was found less often in histologically aggressive tumours than in other sub-types. Immunoglobulins, predominantly IgM, were demonstrated in all but one of these thirty cases, corresponding to the distribution of the amyloid deposits. Electron microscopy revealed 'early' amyloid in one case which showed numerous stromal IgM bodies on immunofluorescence but no evidence of amyloid by routine histochemical methods.
Proximal tubular adenoma of the kidney.
A case of proximal tubular adenoma of the kidney (renal "oncocytoma"), confirmed by electron microscopy, is reported. This benign tumour has been mistaken for renal adenocarcinoma in the past by both surgeons and pathologists.
Spontaneous regression in basal cell carcinomas.
Evidence of previous spontaneous regression was found in 6% of 400 randomly selected basal cell carcinomas. A further 14% showed small foci of active regression usually less than 1 high power field in area and characterized by a lymphocytic infiltrate of tumor nests associated with many apoptotic tumor cells. Spontaneous regression of basal cell carcinomas has been paid scant attention in the past.
Cystic chromomycosis of the skin.
Five patients with solitary cystic granulomatous lesions of the skin are described. Wood splinters and brown pigmented fungal elements were present in all 5 cases. "Cystic chromomycosis" is suggested as an appropriate title to avoid confusion with the cutaneous verrucous form, chromoblastomycosis.
Apoptosis. Its nature and implications for dermatopathology.
Apoptosis is a distinctive mode of cell death with characteristic morphologic features which serves as a balance to mitosis in regulating the size of animal tissues. In contrast to coagulative necrosis, the cytologic features of apoptosis suggest active self-destructive rather than progressive disintegration. It typically affects scattered individual cells which condense and bud to produce many membrane-bounded fragments in which organelles appear intact when viewed by the electron microscope. These apoptotic bodies are then phagocytosed and digested by cells resident in the tissue. Apoptosis, unlike coagulative necrosis, does not itself evoke an inflammatory response. Apoptosis is a feature of such diverse processes as deletion of phylogenetic vestiges during normal embryonic development, involution of endocrine-dependent organs after withdrawal of trophic hormones, cell-mediated immune attack on tissues, and therapeutically induced regression of neoplasms. Apoptosis has received scant attention in dermatopathology. However, it is now known to be an important feature of lichen planus, certain drug eruptions, the skin lesions of graft-versus-host reactions, the regression of plane warts, and the effects of ultraviolet damage. It is also involved in the kinetics of cutaneous neoplasms. In some of these situations, apoptotic bodies have, in the past, been given names such as Civatte bodies, colloid bodies, single-cell necrobiosis, sunburn cells, and dyskeratotic cells without their basic nature having been recognized.
Measurements of tumor thickness.
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