John M. Joelson

Intravenous recombinant tissue-type plasminogen activator in patients with unstable angina pectoris. Results of a placebo-controlled, randomized trial.

Because thrombus formation may contribute to coronary obstruction in patients with unstable angina pectoris, we performed a pilot investigation to determine whether thrombolytic therapy can relieve coronary narrowing in this acute ischemic syndrome. Sixty-seven patients with rest angina and angiographic evidence of coronary stenosis were randomly assigned to receive either low-dose intravenous recombinant tissue-type plasminogen activator (rt-PA) (0.75 mg/kg over 1 hour), high-dose intravenous rt-PA (0.75 mg/kg over 1 hour; total dose, 100 mg over 6 hours), or intravenous placebo followed by repeat coronary angiography at 24-48 hours to assess change in the severity of coronary narrowing. Each patient also received oral aspirin and intravenous heparin. Mean values of coronary stenosis severity (percent of diameter reduction) declined to a similar extent in each group: placebo, 75 +/- 14% to 72 +/- 14% (p = 0.07); low-dose rt-PA, 75 +/- 16% to 71 +/- 18% (p = 0.03), and high-dose rt-PA, 82 +/- 11% to 77 +/- 17% (p = 0.18), with only the low-dose rt-PA group achieving statistical significance. Resolution of intracoronary filling defects, increase in antegrade flow grade, or both also occurred equally among the three groups. There was considerable variation in individual patient response. Between 29% and 50% of patients within each group demonstrated a decrease in stenosis severity, whereas 50% to 57% noted either improvement in antegrade flow or resolution of intracoronary thrombus. There was no difference in incidence of major bleeding events among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Vibrotactile temporal summation for threshold and suprathreshold levels of stimulation

Threshold measurement and matching procedures were used to determine the amount of temporal summation at threshold and suprathreshold levels of vibrotactile stimulation on the thenar eminence of the hand. The frequency of the stimulus was 25, 40, 80, or 200 Hz. At 25 Hz, temporal summation was absent at all intensity levels. Considerable amounts of temporal summation were observed for 80- and 200-Hz stimuli, although the effects decreased as a function of intensity. At 40 Hz, no temporal summation was observed at threshold, but above threshold, a small amount was observed at all intensity levels. The results support a duplex model of mechanoreception in which one of two receptor systems exhibits temporal summation.

Angiographic findings when chest pain recurs after successful percutaneous transluminal coronary angioplasty

Angiographic and clinical characteristics of 102 consecutive patients who underwent coronary cineangiography for assessment of recurrent angina pectoris after successful percutaneous transluminal coronary angioplasty (PTCA) were reviewed. Based on angiographic findings, patients were classified as having restenosis (n = 63), development of new, significant coronary stenosis (n = 15), incomplete revascularization (n = 9) or no significant coronary artery disease (n = 15). Eighteen clinical and technical characteristics of the study group were analyzed as predictors of angiographic outcome. The groups did not differ in terms of age, gender, number of inflations performed, peak inflation pressure or in the pre- or post-PTCA stenosis or gradient. The time from PTCA to onset of recurrent angina was the most powerful predictor of angiographic outcome. Patients in whom symptoms developed within 1 month of PTCA usually had incomplete revascularization or no coronary narrowing. Restenosis was the most common explanation for chest pain 1 to 6 months after PTCA. Angina recurring more than 6 months after PTCA was usually due to development of new, significant coronary artery narrowings.

Properties of Categories in Semantic Memory.

Properties of categories were investigated by analyzing 22 measures of the 56 categories used in the 1969 Battig and Montague norms. A factor analysis of the data indicated that categories in semantic memory possess at least four factors that may affect the use and comprehension of categories. These factors were tentatively interpreted as reflecting the properties of category familiarity, category size, category-label printed frequency, and a categorys semantic complexity. Additionally, the correlation matrix and the factorpattern matrix allow many insights into other semantic properties, such as meaningfullness, abstract-concreteness, and homographic characteristics of category labels.

Severe Aortic Coarctation in an Adult Without Left Ventricular Hypertrophy Nor Overt Collateral Channels.

We describe an unusual case of periductal coarctation of the aorta in a 40‐year‐old patient presenting to the echocardiography laboratory for evaluation of a heart murmur. Subsequent clinical history revealed easy fatigability, dyspnea on exertion, and hypertension. Despite a lack of left ventricular hypertrophy, aortic coarctation was suggested by echocardiography. It was later confirmed to be severe by multiple additional imaging modalities, despite an absence of overt collateral arterial channels. The importance of echocardiography in the diagnosis of coarctation of the aorta and the management of this complicated patient is discussed.

The role of visual and acoustic coding in retrieval from very short-term memory

Several studies have implicated acoustic processing in short-term memory despite stimuli being visual. It is commonly assumed that very short-term memory (VSTM) for visual stimuli, in contrast, operates entirely in the modality of input. The present study tested this assumption by investigating whether an acoustic code is used in VSTM. An experiment required subjects to detect whether a critical letter was present or absent in a brief display of 16 letters. Latency and accuracy of detection were not affected by acoustic similarity but were affected by visual similarity between the critical letter and the other letters of the display. Thus, the results support the assumption that retrieval from very short-term memory (visual) does not involve acoustic information.