Biomedical subjects
Publications and source records attributed to R A Evans.
This study illustrates detailed cerebral anatomy that can be consistently visualized on computed tomography scans after a rapid high dose of contrast substance has been infused. A thorough knowledge of anatomy is required not only to detect and precisely localize lesions but to avoid ascribing pathological significance to normal, contrast enhanced structures.
A rapid, simple, and inexpensive computed tomographic technique has been developed for marking the scalp and lateral skull radiograph of patients with small cerebral convexity lesions. The more precise localization provided thereby facilitates planning and performance of surgery.
Oblique projection vertebral angiography is the simplest and most accurate angiographic method of detecting small cerebellopontine angle tumors. The vascular blood supply to the tumor and brainstem is displayed as the surgeon will encounter it during lateral suboccipital craniotomy. The procedure is comfortable for the patient, technically easy to perform, and reproducible. Interpretation is relatively unaffected by variations in vascular anatomy or superimposed vessel or bone images. This method can be used to supplement routine views, or be performed alone with stereoscopic filming.
The diagnostic accuracy of CT scanning in the sellar area can be improved by using a rapid high dose (RHD) contrast technique which visualizes the supraclinoid carotid arteries, cavernous sinus and vascular plexus of the infundibulum. The RHD technique is briefly described and the pertinent anatomy discussed and illustrated.
Ten patients were studied in whom precontrast computed tomography (CT) revealed an isodense mass which obliterated cerebral sulci and deformed the ventricle(s). Upon rapid-high-dose (RHD) contrast enhancement, the cerebral hemispheric surface was so well demonstrated, that in 4 patients the possibility of an isodense subdural hematoma was exluded, while in the other 6 it was correctly diagnosed. Preoperative angiography was not necessary.
The choroid plexus of the fourth ventricle is a sensitive, symmetrical CT landmark which can often be visualized in overlapped scans performed in the orbital plane during rapid infusion of a high dose of iodinated contrast substance. Normal and pertinent abnormal plexus configurations are described and illustrated.
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The Primary Rabbit Dermal Irritation Assay as described in the Federal Hazardous Substances Act (FHSA) is used by the Consumer Products Safety Commission (CPSC) to determine the labeling requirements of household products. One of the more obvious deficiencies of this assay is the descriptive imprecision for preparing the form in which solid materials are applied. Our experimental findings show that form and concentration of test material as well as the length of contact with the skin and the degree of patch occlusivity are prime factors influencing the degree of skin change. Four detergent granular products are evaluated. In the dry powder form with 4 hour exposure all the detergents were non-irritating. The paste at 24 hours under total occlusion was the most irritating.
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Nine patients with painful Paget's disease of bone were treated for 200 days with a drug combination designed to elevated plasma calcium, hence stimulating the production of endogenous calcitoning and suppressing that of parathyroid hormone. This combination was oral calcium, a thiazide diuretic, a low phosphorus diet and aluminium hydroxide. Eight of the nine patients experienced sustained pain relief after 20--70 days. The mean plasma alkaline phosphatase (expressed as a percentage of the pre-treatment level) commenced to fall after 30 days of treatment and at 120 days was 58% of the pre-treatment level; this fall was sustained at 200 days. There was a mean rise of 0-08 mmol/l in plasma calcium; there was no significant change in plasma inorganic phosphorus or plasma creatinine. In view of the extremely low cost of this drug combination and its lack of side-effects, it is suggested it be considered as a treatment for Paget's disease of bone.
Early clinical application of an off-line image processing and analysis system for digital display in conjunction with computed tomography is described. The system consists of three operational subsystems: (a) a flexible disk for digital storage of absorption values in each of eight or more tomographic planes; (b) a high-speed interactive video system which displays the tomographic plane in correct geometry with the absorption values, which serve as the pictorial elements; and (c) a paper hard copy of the absorption values in a simulated gray-tone image of the tomographic plane in which the numerical values are the pictorial elements. Both the video and paper displays provide explicit numerical values of x-ray attenuation for each location on the tomographic plane in an image which combines analog and digital qualities.
Twenty-four sixth graders, 24 seventh graders, and 24 special-education students with MAs roughly equivalent to the sixth graders were randomly assigned to the cells of a 3 (grade level) X 2 (list novelty) X 2 (list organization) factorial design. In the list-novelty condition, subjects were immediately transferred to either a same-categories or a new-categories list on the third and fourth trials. In the list-organization condition, subjects received the lists on the first two trials in either a random or blocked format. For all subjects, the last two trials were presented randomly and contained new words. The results of the analyses revealed that there was significant negative transfer over trial blocks for the same-categories transfer condition. In addition, the new-categories group clustered significantly more on the second than the first trial block. There was no significant interaction between subject and treatment factors, suggesting that the processes involved in recall were similar for nonretarded and borderline retarded subjects.
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A case of a rare form of penile testicular ectopia is reported. The embryology is discussed, and ectopia is differentiated from cryptorchism.
Non-traumatic spontaneous rupture of the otherwise normal bladder is a rare occurrence. The literature is reviewed and 4 new cases are reported. Experimental data are presented and a theory is reviewed regarding the frequent intraperitoneal location of the rupture. The frequent paucity of symptoms compared to the high mortality rate is stressed.