Biomedical subjects
S T Elliott
Publications and source records attributed to S T Elliott.
Landed XRD/XRF analysis of prime targets in the search for past or present Martian life.
Mars landers seeking evidence for past or present life will be guided by information from orbital mapping and from previous surface exploration. Several target options have been proposed, including sites that may harbor extant life and sites most likely to preserve evidence of past life These sites have specific mineralogic characteristics. Extant life might be gathered around the sinters and associated mineral deposits of rare active fumaroles, or held within brine pockets and inclusions in a few evaporite-mineral deposits. Possibilities for fossilization include deltaic and lake-bottom sediments of once-flooded craters, sinters formed by ancient hot-spring deposits, and the carbonate deposits associated with some evaporite systems. However, the highly varied mineralogy of fossil occurrences on Earth leads to the inference that Mars, an equally complex planet, could host a broad variety of potential fossilizing deposits. The abundance of volcanic systems on Mars and evidence for close associations between volcanism and water release suggest possibilities of organism entrapment and mineralization in volcaniclastic deposits, as found in some instances on Earth. Thus the targets being considered for exploration include a wide variety of unique deposits that would be characterized by silica or various nonsilicate minerals. Beyond these "special" deposits and in the most general case, an ability to distinguish mineralized from uncemented volcanic detritus may be the key to success in finding possible fossil-bearing authigenic mineralogies. A prototype miniaturized X ray diffraction/X ray fluorescence (XRD/XRF) instrument has been evaluated with silica, carbonate, and sulfate minerals and with a basalt, to examine the capabilities of this tool in mineralogic and petrologic exploration for exobiological goals. This instrument. CHEMIN (chemical and mineralogical analyzer), is based on an innovative low-power X ray tube, transmission geometry, and CCD collection and discrimination of diffracted and fluoresced X rays. The ability to accumulate and integrate the entire circumference of each complete Debye diffraction ring compensates for poor powder preparations, as might be produced by robotic sampling systems. With CHEMIN, a wide range of minerals can be uniquely identified. Using Rietveld analysis of the XRD results, mineral quantification is also possible. Expanded capabilities in phase analysis and constrained data solutions using quantitative XRD and XRF are within reach.
Case report: Pulmonary leiomyosarcoma presenting as a pseudoaneurysm.
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The ultrasound appearances of scrotal oedema.
Ultrasound has been shown to be a useful tool in the investigation of both acute and chronic scrotal conditions. We describe the ultrasound appearances of scrotal oedema with different aetiologies. A total of eight patients with scrotal oedema resulting from a variety of conditions, including heart failure, idiopathic lymphoedema, hepatic failure and lymphatic and venous obstruction, underwent ultrasound of the scrotum to determine the appearances common to each case. In all cases, similar appearances of a thickened scrotal wall with an 'onion' like appearance surrounding normal testicles was seen. The scrotal wall had a jelly like texture. Awareness of the typical appearances of scrotal oedema on ultrasound and a knowledge of its causes is helpful in distinguishing it from other causes of a swollen scrotum.
Case report: A rapidly expanding testicular mass due to a ruptured ovarian follicle.
An ovotestis is the commonest gonad in the small number of patients who are true hermaphrodites. In the majority of ovotestes, testicular and ovarian tissue is arranged end-to-end. There has been only one previous report of the sonographic appearances of an ovotestis. We present the sonographic findings in a patient who developed a rapidly enlarging upper pole testicular mass, which was found on histology to be a ruptured ovarian follicle with spermatogenesis occurring within the adjacent testicular tissue.
Pleural effusions, diaphragm inversion, and paradox: new observations using sonography.
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Low-reflectivity periportal collar on hepatic ultrasound.
A low attenuation periportal collar is frequently found on computed tomography (CT) in association with a variety of liver diseases and other conditions (Lawson, T L, Thorsen, M K, Erikson, S J et al, Periportal halo: a CT sign of liver disease, Abdom. Imaging, 18, 42-46 (1993)). Abnormal periportal intensity has been reported on magnetic resonance imaging (MRI) in various hepatobiliary diseases. Transient low reflectivity periportal cuffing has recently been described and was presumed to be due to periportal lymphoedema associated with malignant lymphadenopathy. We report the finding of such bands in four patients with chronic hepatobiliary disease and present the associated histological findings.
A prospective randomized comparison of fine needle aspiration biopsy and fibreoptic bronchoscopy in the investigation of peripheral pulmonary opacities.
Twenty-nine patients, aged 66(+/- 7) years with a peripheral pulmonary opacity (mean diameter 3.6 +/- 1.8 cm) believed to be a tumor, were randomly allocated to initial investigation by either fibreoptic bronchoscopy or percutaneous fine needle aspiration biopsy, the latter performed under fluoroscopic control. The patients proceeded to the alternative investigation in the event of the first failing to achieve a diagnosis. Malignancy was confirmed by the initial procedure in 14/15 patients randomized to fine needle aspiration biopsy but only in 1/14 patients randomized to fibreoptic bronchoscopy (P less than 0.01). Overall, these figures were 25/28 fine needle aspiration biopsy and 2/15 fibreoptic bronchoscopy (P less than 0.01). These results confirm the clinical suspicion that fine needle aspiration biopsy is far more likely than fibreoptic bronchoscopy to establish the presence of malignancy in peripheral pulmonary opacities.
Diazacholesterol-induced ichthyosis in the hairless mouse. Assay for comparative potency of topical retinoids.
Although the new synthetic retinoids are effective when administered systemically, they have not been shown to be effective as topical agents. We compared the topical activity of six synthetic retinoids (two arotinoids, etretinate, all-trans- and 13-cis-tetrazole-retinamide, isotretinoin, and tretinoin) on tail skin in the diazacholesterol-fed mouse model of ichthyosis. Responses were assessed clinically and by measurement of stratum corneum thickness. Although the arotinoids dramatically reduced scaling, they were toxic at concentrations above 0.1%, as was etretinate at 1.0% or greater. Lower concentrations were effective without producing local or systemic toxic reactions. Clinical responses were paralleled by equivalent decrements in stratum corneum thickness, which also permitted quantitative comparisons. The order of potency for the retinoids was as follows: arotinoids, etretinate, tetrazole-retinamides, tretinoin = isotretinoin, vehicle. These results demonstrate that (1) the synthetic retinoids hold promise as topical agents; (2) irritation is not an absolute requirement for topical retinoid activity; and (3) the diazacholesterol-fed mouse offers a new assay of topical retinoid potency in a well-defined animal model of ichthyosis.
X-linked ichthyosis: a metabolic disease.
Sex-linked ichthyosis, a rather common genodermatosis, has recently been linked with deficiency of the enzyme steroid sulfatase. Data supporting this association and suggesting that alterations in lipid metabolism may cause abnormal keratinization are herein reviewed.
Delayed cutaneous hypersensitivity and lymphocyte transformation: dissociation in atopic dermatitis.
Studies of cell mediated immunity (CMI) in atopic dermatitis have demonstrated various defects and frequently contradictory results. The true nature of immune dysfunction remains uncertain. We approached this question by concurrently examining two aspects of CMI: delayed cutaneous hypersensitivity and in vitro lymphocyte transformation. Responses were tested using the antigens Candida albicans and streptokinase-streptodornase (SKSD). Mean lymphocyte transformation was equal in atopic patients and controls, although a subgroup of severely dermatitic patients showed depressed responses. Cutaneous anergy was the rule in atopic patients (96% to candidin and 84% to SKSD). Although normal subjects showed good correlation between in vitro and cutaneous responses, atopic patients showed a significant lack of correlation. Many patients manifested cutaneous anergy in the face of normal lymphocyte transformation re sponses.
Lymphocyte response to phytohemagglutinin in atopic dermatitis.
Studies of patients with atopic dermatitis (AD) have demonstrated several clinical and laboratory indications of immunity defects, but with frequently contradictory results. We have recently shown that many patients with negative cutaneous delayed type hypersensitivity to candidin and streptokinase-streptodornase may have normal in vitro lymphocyte transformation to the same antigens. We hypothesized that this represents recovery of immunocompetent cells when they are isolated in vitro. This report describes phytohemagglutinin-induced transformation of lymphocytes immediately after isolation and after four days in culture (precultured). Responses of lymphocytes from patients with AD were initially subnormal, but increased to normal levels after the preculture period. Our results suggest that defective immune function in AD is not due to a permanent intrinsic lymphocyte defect, but is more likely due to factors associated with disease activity and severity.
Percutaneous ablation of peripheral pseudoaneurysms using thrombin: a simple and effective solution.
PURPOSE: To assess the effectiveness of tissue adhesive and thrombin solution in the percutaneous ablation of peripheral artery pseudoaneurysms. METHODS: Twenty-five pseudoaneurysms were treated over a 33-month period; all had failed ultrasound-guided compression. Tissue adhesive or thrombin solution was injected percutaneously, with needle tip position and changes within the aneurysm confirmed with color Doppler ultrasound. In 19 cases we utilized a protective balloon inflated across the aneurysm neck prior to the injection of tissue adhesive and in six cases used thrombin injection alone. Seven patients were anticoagulated. Patients were followed up after the procedure. RESULTS: All 25 aneurysms were treated successfully; two patients required a return visit and there were no immediate complications or peripheral emboli detected. One patient developed a contralateral pseudoaneurysm. CONCLUSIONS: The percutaneous injection of pseudoaneurysms is a safe, atraumatic, and effective treatment for femoral artery pseudoaneurysms in the peripheral circulation. There are significant advantages over ultrasound-guided compression or surgical repair.