Anti-metabolic extract from the brain of Protopterus aethiopicus.
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Animals↗
Biomedical subjects
K Knox
Publications and source records attributed to K Knox.
Validity of generic risk factors and the strain index for predicting nontraumatic distal upper extremity morbidity.
Nine individual generic risk factors, eight combinations of generic risk factors, the presence of any generic risk factor, and the Strain Index were evaluated for 56 jobs by 2 evaluators blinded to morbidity measures. Jobs then were assigned to dichotomous hazard classifications (problem versus safe) according to recommendations from the literature. OSHA 200 logs were used to ascertain historical evidence of distal upper extremity (DUE) morbidity, and jobs were assigned to a dichotomous morbidity classification (positive versus negative) using none versus one or more recorded cases as the criterion. Evidence of association and measures of predictive validity were evaluated by comparing hazard and morbidity classifications using 2 x 2 contingency tables. Five individual generic risk factors, three generic risk factor combinations, and the presence of any generic risk factor were not associated with morbidity classification. The odds ratio estimates among the four individual generic risk factors and the five combinations of generic risk factors associated with DUE morbidity varied from 3.3-36.0. The Strain Index had the largest estimated odds ratio of any exposure factor at 108.3. The exposure methods were grouped according to patterns of predictive validity. With one exception, the individual generic risk factors and their combinations had high sensitivity with low specificity (many false-positives), low sensitivity with high specificity (many false-negatives), or low sensitivity with low specificity. The only generic risk factor that demonstrated reasonable predictive validity was the use of gloves--its sensitivity, specificity, positive predictive value, and negative predictive value were equal to 0.75. The Strain Index performed better than any of the individual or combinations of generic risk factors. Its sensitivity, specificity, positive predictive value, and negative predictive value were all approximately 0.90.
Arm↗
Double-echo MPGR imaging of the rotator cuff.
T2-weighted gradient recalled (T2*) sequences are often used in place of T2 sequences when imaging the shoulder. The main advantages of these sequences are the decreased imaging time, the better demonstration of cartilage disorders, and the added tissue information that can be garnered due to the increased sensitivity to magnetic susceptibility with T2* sequences. Unfortunately, one drawback of T2* sequences that is less apparent with spin-echo techniques is the sensitivity of tissue close to the surface coil to undergo diffusely increased signal throughout an area in close proximity to the coil (coil-burnout). This phenomenon is a very bothersome artifact that can obscure tissue differentiation in this area. Fluid detection, especially in the subacromial bursa, can be especially difficult to diagnose in the presence of coil-burnout. We describe MR imaging of the shoulder using double-echo T2-weighted multiplanar gradient recalled sequences, which allow better evaluation of shoulder pathology.
Humans↗
Flow dynamics in a lethal anterior communicating artery aneurysm.
We describe and analyze the flow dynamics in replicas of a human anterior communicating artery aneurysm. The replicas were placed in a circuit of pulsating non-Newtonian fluid, and flows were adjusted to replicate human physiologic parameters. Individual slipstreams were opacified with isobaric dyes, and images were recorded on film and by CT/MR angiography. When flow in the afferent (internal carotid) and efferent (anterior and middle cerebral) arteries was bilaterally equal, slipstreams rarely entered the aneurysm. When flow in either the afferent or efferent vessels was not symmetrical, however, slipstreams entered the aneurysm neck, impinged upon the aneurysm dome, and swirled within the aneurysm. Unequal flow in carotid or cerebral systems may be necessary to direct pathologic, fluid slipstreams into an aneurysm.
Aneurysm, Ruptured↗