Efficacy of gadolinium in MR brain imaging of HIV-infected patients

PURPOSE: To determine the value of gadolinium in routine head MR imaging of HIV-infected patients. METHODS: One hundred and three consecutive human immunodeficiency virus-infected patients referred for head MR imaging were scanned without and with intravenous gadopentetate dimeglumine (Gd-DTPA) contrast. RESULTS: The precontrast scans of 82 patients were either normal, or had atrophy or diffuse white matter changes only. Sixteen of these 82 demonstrated enhancing abnormalities: eight meningeal/ependymal enhancement and eight focal enhancing lesions. Twenty-one of the 103 scans had focal or mass lesions on the precontrast images; in eight of these scans, new information was obtained with Gd-DTPA. Of the 24 patients in both groups where new information was obtained with Gd-DTPA, the information contributed to a change in the clinical care of nine patients. CONCLUSION: Gadolinium-enhanced MR is useful in the management of selected patients with human immunodeficiency virus infection, for example those with symptoms suggesting meningeal involvement, focal brain lesions, or if the unenhanced MR does not explain all the patient's symptoms.     

Multimode propagation on radiating traveling-wave structures with glide-symmetric excitation

Standing-wave measurements on a periodic traveling-wave array of dipoles driven with glide-symmetric excitation from a coaxial transmission line show the existence of multimode propagation in certain frequency bands. This phenomenon is explianed qualitatively in terms of coupling of symmetric and antisymmetric modes of the dipole array by the excitation from an unbalanced line. It has not been found when the dipoles are driven from a balanced two-conductor line. The avoidance of such multimode phenomena is crucial to the self-balancing property of successful log-periodic dipole arrays.     

Application of coherence theory to propagation of a quasi-monochromatic field in a random medium

Starting from the partial differential equation for scalar wave propagation in a random medium, an integral equation is derived for the propagation of the second-order correlation function. In order to obtain the exact integral equation without resorting to perturbation theory, it is necessary to assume statistical independence of the wave function and the refractive index fluctuations. The physical basis for this assumption is reviewed, and a criterion for its applicability is proposed. The integral equation for the second-order correlation is then transformed into a wavenumber-spectral representation, resulting in appreciable simplification and permitting some direct interpretation.     

The design of Apple—A language for modular programs

Sometimes programming is difficult because of the amount of detail that is relevant to the problem being solved. A suitable language for these problems should aid the programmer in organizing a program as a synthesis of parts. Apple is a language designed for such applications. It is a typed language in which functions are objects, and it provides three complementary ways to modularize programs. These are the definition of environments, the use of functional abstraction, and the use of data abstraction or parameterized, abstract data types.In this paper we describe the main features of Apple, and explain the motivation for many of the design decisions. Another document furnishes a formal definition.     

Assessment of coenzyme Q10 tolerability in Huntington''s disease

BACKGROUND: Maintaining viability of periodontal ligament cells is important after an avulsion injury occurs. OBJECTIVE: This study examined cell death and compared different transport media at varying times. Lactate dehydrogenase (LD) measurements were made on root surfaces of extracted teeth for evaluating the results of breakdown and necrosis of periodontal ligament cells. STUDY DESIGN: Teeth were divided into three groups. Each was immersed in one of the following storage media: Hanks balanced salt solution, Custodiol solution (an organ storage medium), or sterile saline solution. I.D. measurements (an indicator of cell death) were made at 2, 6, 24, 72, and 168 hours after extraction. RESULTS: When the LD levels were compared according to the time periods, a progressive increase of cell death was found to be statistically significant (p < 0.001). However, when the effects of both time periods and the kind of storage medium on the LD levels were examined, the LD levels of the saline solution storage medium were found to be significantly higher (p < 0.001) than that of the other two groups. CONCLUSIONS: Both Hanks balanced salt solution and Custodiol appeared to be suitable transport media for maintaining cell viability, whereas saline solution was not.     

Levodopa improves motor function without impairing cognition in mild non-demented Parkinson's disease patients. Parkinson Study Group

OBJECTIVE: The objective of the study was to determine the effects of short-term levodopa administration on motor, cognitive, and psychiatric aspects of Parkinson's disease (PD). BACKGROUND: The effects of levodopa on mental processes in PD are controversial. Opinions range from the claim that levodopa improves cognition to the opposite view that levodopa causes or exacerbates dementia, delusions, and hallucinations. Of the 800 idiopathic PD patients enrolled in the original DATATOP study, 387 reached the end point of functional disabilities sufficiently severe to require levodopa treatment. There were 263 men and 124 women who were comparable with regard to age, symptom duration of PD, and measures of PD severity. We compared test scores on motor performance, cognitive function, and psychiatric status before levodopa and again within 6 months after initiation of levodopa therapy. RESULTS: Levodopa administration improved all motor functions significantly. The improvement was significantly greater in women than in men. Levodopa administration did not worsen scores on any cognitive tests, and there were quantitatively small but significant improvements in tests of frontal lobe function. Levodopa exerted only minor effects on psychiatric measures. There were small but significant decreases in scores for depression, and increases in vivid dreams and hallucinations. CONCLUSIONS: Levodopa administration for up to 6 months in dosages sufficient to improve motor function has only small effects on cognitive function and psychiatric status in mild to moderate PD patients. We conclude that motor symptoms in early PD, which result from dopamine depletion, are dissociable from cognitive functions and psychiatric status, which may be more dependent on nondopaminergic mechanisms.     

The formal definition of a real-time language

Summary This paper presents the formal definition of TOMAL (Task-Oriented Microprocessor Applications Language), a programming language intended for real-time systems running on small processors. The formal definition addresses all aspects of the language. Because some modes of semantic definition seem particularly well-suited to certain aspects of a language, and not as suitable for others, the formal definition employs several complementary modes of definition.The primary definition is axiomatic and is employed to define most statements of the language. Simple, denotational (but not lattice-theoretic) semantics complement the axiomatic semantics to define type-related features, such as binding of names to types, data type coercions, and evaluation of expressions. Together, the axiomatic and denotational semantics define all features of the sequential language. An operational definition is used to define real-time execution, and to extend the axiomatic definition to account for all aspects of concurrent execution. Semantic constraints, sufficient to guarantee conformity of a program with the axiomatic definition, can be checked by analysis of a TOMAL program at compilation.     

A randomized trial of amitriptyline and mexiletine for painful neuropathy in HIV infection. AIDS Clinical Trial Group 242 Protocol Team

BACKGROUND: Painful sensory neuropathy is a common complication of HIV infection. Based on prior uncontrolled observations, we hypothesized that amitriptyline or mexiletine would improve the pain symptoms. METHOD: A randomized, double-blind, 10-week trial of 145 patients assigned equally to amitriptyline, mexiletine, or matching placebo. The primary outcome measure was the change in pain intensity between baseline and the final visit. RESULTS: The improvement in amitriptyline group (0.31+/-0.31 units [mean+/-SD]) and mexiletine group (0.23+/-0.41) was not significantly different from placebo (0.20+/-0.30). Both interventions were generally well tolerated. CONCLUSIONS: Neither amitriptyline nor mexiletine provide significant pain relief in patients with HIV-associated painful sensory neuropathy.     

A Logic for Rewriting Strategies

Rewriting strategies can become quite complex and are not easy to comprehend or reason about when they are expressed in operational terms. This paper develops a weakest precondition logic for reasoning about strategies programmed in the strategy language Stratego. This logic embeds the modal mu-calculus, allowing it to express properties of terms of arbitrary depth. Its use is illustrated by characterizing properties of several reduction strategies for the lambda calculus with explicit substitutions.