Uncovering psychiatric test information with graphical techniques of Exploratory Data Analysis.

This article illustrates how Exploratory Data Analysis (EDA) can complement conventional statistical methods in evaluating psychiatric tests. Using one recent EDA computer program, we evaluated the ability of repeated psychiatric screening tests (the General Health Questionnaire [GHQ]) to predict medical and psychiatric service use in a Health Maintenance Organization (HMO), the Harvard Community Health Plan (HCHP). Using a stratified random sample of 244 new HCHP enrollees and viewing three-dimensional graphs of their data from multiple perspectives, we found two subpopulations: low GHQ scorers, for whom the tests did not predict service use; and high scorers, for whom they did. Surprisingly, improving scores forecast increased use and chronically high scores predicted diminished use. Using another stratified random sample of 213 new HCHP enrollees, and with scatterplot matrices from another interactive computer program, we found that high and unchanging GHQ scores forecast HMO dropout. We examine possible interpretations--for example, that chronically distressed patients may become immobilized, diminish service use, and ultimately leave the HMO. We also explain how EDA methods may help uncover elusive results in other data (e.g., mental health outcomes).     

Responsiveness and calibration of the general well-being adjustment scale in patients with hypertension

We examined the discriminant ability and responsiveness of the General Well-Being Adjustment Scale in patients enrolled in a randomized clinical trial of antihypertensive therapy. We also tried to translate the effects of physical symptoms on general well-being. This secondary analysis used demographic, clinical, physical symptom, and general well-being data for 545 white, male hypertensive patients. General well-being was measured by the General Well-Being Adjustment Scale (GWB) collected on 2 occasions over 8 weeks of treatment. Patients with any one of 14 physical symptoms or problems, compared to those without symptoms, had lower GWB scores (p < 0.003 to p < 0.0001). Decreases of 2.83–8.76 points in GWB scores were observed in patients developing physical symptoms over the 8 week study period (p < 0.05 to p < 0.0001). These effects were demonstrated in patients developing cold sensitivity, sexual problems, chest pain, shortness of breath, loss of taste, nausea, hot or cold spells, numbness and tingling, dry mouth, blurred vision, and dizziness. We conclude that the GWB is responsive to clinically meaningful changes in symptoms and may provide a more complete evaluation of the effects of medical treatment. The GWB is a valid and responsive measure of health status outcomes in the evaluation of antihypertensive treatment.     

A method of simultaneous dual-radionuclide cardiac imaging with technetium 99m and thallium 201. I: Analysis of interradionuclide crossover and validation in phantoms

Background  

Simultaneous dual-radionuclide technetium 99m/thallium 201 scintigraphy can potentially produce perfectly aligned stress and rest images in less time than conventional protocols. However, interradionuclide crossover limits diagnostic accuracy. Accordingly, we evaluated^99mTc and²⁰¹Tl crossover in line and heart phantoms.     

Molecular properties and structure-function relationships of lethal peptides from venom of Wagler's pit viper, Trimeresurus wagleri.

Two new lethal peptides (waglerins) were purified from the venom of Trimeresurus wagleri, and sequenced. We found them to be analogs of lethal peptides (waglerins) I and II reported previously (Weinstein et al., Toxicon 29, 227-236, 1991), with an additional Ser-Leu on the amino terminus. Three of the four waglerins were synthesized and the products were chemically and biologically equivalent to the naturally occurring counterparts in venom. Murine i.p. LD50 for synthetic waglerins I, SL-I and II were 0.33, 0.22, and 0.51 mg/kg, respectively. The single, intramolecular disulfide bond in each synthetic peptide formed rapidly in high yield. The reduced (cysteine-containing) forms of the peptides appeared to have significant toxicities, even without prior disulfide bond formation, but synthetic analogs with serine substituted for cysteine were not toxic. The synthetic dimer of waglerin I, formed by two intermolecular disulfide bonds, was not toxic, but rapidly rearranged to lethal, monomeric waglerin I at alkaline pH upon the addition of 5 mM beta-mercaptoethanol. Waglerin I was inactivated by cleavage at Tyr-15 with chymotrypsin.