Publications

The clinical and biological features of Alzheimer disease are not uniform in their expression; heterogeneity is evident in the disease's clinical, anatomic, and physiologic characteristics. The presence of considerable intersubject and intrasubject heterogeneity suggests that subtypes of the disease exist. We define subtypes of Alzheimer disease in regard to the behavioral features (for example, predominant right or left hemisphere, or symmetrical impairment), inheritance (familial or sporadic), dosage of chromosome 21 (presence of the Down syndrome), time course of progression, age of onset (presenile or senile), and presence or absence of motor deficit (myoclonus or signs of an extrapyramidal syndrome). Studies of regional cerebral glucose metabolism with positron emission tomography and [18-fluorine] fluorodeoxyglucose show focal alterations in glucose use, with cerebral metabolic asymmetries in patients with Alzheimer disease that are related to the nature of the cognitive deficit. Serial roentgenographic computed tomographic studies show heterogeneous rates of lateral ventricle enlargement in the disease that are related to rates of cognitive decline. Similar anatomic and physiologic abnormalities are also found in persons 45 years of age or older who have the Down syndrome. Furthermore, patients with Alzheimer disease who have extrapyramidal dysfunction or myoclonus are a distinct subgroup, with specific abnormalities of central monoamine markers of dopamine metabolism, serotonin metabolism, and the hydroxylation cofactor, biopterin. The concept of subtypes in Alzheimer disease serves as a model with which the interactions of genetic influences with environmental factors can be examined.

Modification of risk factors in patients who have had myocardial infarctions has received little attention in the literature. Yet, major modifiable risk factors for recurrent coronary heart disease, including hypertension, smoking, increased serum cholesterol levels, sedentary lifestyle, and obesity are the same risk factors for its development. Although coronary atherosclerosis is already established in patients who have had a myocardial infarction, evidence suggests that important reductions in recurrent coronary heart disease and death can be achieved through secondary prevention programs that modify risk factors. The high risk for recurrence and mortality in patients who survive a heart attack means that substantial reductions in the rates of these events can be achieved with relatively small reductions in risk factors. Patients who have had a myocardial infarction are also active participants in health care and are likely to be highly motivated to modify their risks for cardiac disease.

We examined the potential for IgE-mediated cross-reactivity between the carbepenems, a new class of beta-lactam antibiotics, represented by imipenem, and penicillins. In vivo skin testing with the relevant imipenem and penicillin determinants was undertaken. Having determined the concentrations of imipenem materials that did not induce false positive skin tests in nonpenicillin-allergic control subjects, we tested 40 subjects with a history of penicillin-allergic reactions. Twenty of these subjects were found to be nonallergic to penicillin on skin testing, and none of these subjects reacted to the imipendem determinants. In contrast, half the 20 subjects who were positive to one or more penicillin determinants also reacted to imipenem reagents. There was a good correlation between the penicillin and imipenem reagents to which the patients reacted. Imipenem should only be administered to penicillin-allergic subjects with similar precautions of penicillin administration to such patients.