Jack D. Myers

INTERNIST-I, An Experimental Computer-Based Diagnostic Consultant for General Internal Medicine

INTERNIST-I is an experimental computer program capable of making multiple and complex diagnoses in internal medicine. It differs from most other programs for computer-assisted diagnosis in the generality of its approach and the size and diversity of its knowledge base. To document the strengths and weaknesses of the program we performed a systematic evaluation of the capabilities of INTERNIST-I. Its performance on a series of 19 clinicopathological exercises (Case Records of the Massachusetts General Hospital) published in the Journal appeared qualitatively similar to that of the hospital clinicians but inferior to that of the case discussants. The evaluation demonstrated that the present form of the program is not sufficiently reliable for clinical applications. Specific deficiencies that must be overcome include the program’s inability to reason anatomically or temporally, its inability to construct differential diagnoses spanning multiple problem areas, its occasional attribution of findings to improper causes, and its inability to explain its “thinking.” (N Engl J Med. 1982; 307:468–76.

Familial Muscular Subaortic Stenosis An Unrecognized Form of "Idiopathic Heart Disease," with Clinical and Autopsy Observations

Two families with familial muscular subaortic stenosis have been studied. Hemodynamic data in 2 cases and the operative findings of 1 case are described. Autopsy findings of 3 cases have been presented. Clinical findings indicate at least 3 additional cases in 1 family and 5 in the other. The pedigrees of both families have been discussed. The incidence of this lesion in each family over 3 generations suggests that the defect is related to Mendelian dominant inheritance. To our knowledge, this is the first report of cases of familial heart disease compatible with transmission by a Mendelian dominant gene. The importance of differential diagnosis of this disease from other types of aortic or subaortic stenosis prior to surgery has been stressed, since no operation has been devised for this lesion. The distinguishing clinical features include the apical and lower left sternal border location of the systolic murmur, the absence of poststenotic dilatation of the ascending aorta, the absence of calcification of the aortic value, the absence of a murmur of aortic insufficiency, and the strong family history suggesting a familial trait.

INTERNIST-I Properties: representing common sense and good medical practice in a computerized medical knowledge base

INTERNIST-I is an experimental diagnostic consultant program for use on clinically challenging cases in internal medicine. Properties are a part of the INTERNIST-I knowledge representation scheme which embody essential information about the medical facts contained in the knowledge base. Properties provide the INTERNIST-I program with a measure of common sense and encourage the program to follow good medical practice. Properties substantially influence the behavior of the INTERNIST-I diagnostic program during case analyses. This paper reviews the implementation and significance of properties.

Role of Na-K-atpase in the renal reabsorption of sodium in the elasmobranch, squalus acanthias

Abstract 1. 1. The relative importance of Na-K-activated ATPase in active bulk transport of Na + in the elasmobranch kidney was examined. Fractional Na + excretion was examined before and after the administration of ouabain, associated with over a 60 per cent reduction in enzyme activity, as well as following furosemide and ethacrynic acid. 2. 2. Marked inhibition of Na-K-ATPase with ouabain did not reduce Na + reabsorption, in contrast to furosemide and ethacrynic acid which increased fractional excretion from 0·22 to 0·69. 3. 3. These data suggest that Na-K-ATPase does not participate in bulk transport of Na + in the elasmobranch kidney, where the conservation of Na + is of little importance in osmoregulation.