Missing tissue compensators: evaluation and optimization of a commercial system.

A commercial system for producing retracted compensators has been adapted to suit local needs, and is evaluated here. It comprises a magnetic field surface digitizer and computer-driven milling machine. Improvements in dose distributions, resulting in standard deviations of the mean dose between 2% and 3%, have been achieved for treatment fields in wax phantoms simulating the head and neck regions. Optimization of compensator shape to allow for changes in the amount of scattered radiation has resulted in a further improvement in dose uniformity, particularly near the field borders; for these compensators the standard deviation was as low as 1.6%. The system using the basic algorithm has been in clinical use since July.     

Differential mood changes following basal ganglia vs thalamic lesions

Patients with computed tomographic scan-verified unilateral lesions in the basal ganglia or thalamus were examined for the presence of poststroke mood disorders. Patients with left-sided basal ganglia lesions (mainly in the head of the caudate nucleus) showed a significantly higher frequency and severity of depression, as compared with patients with right-sided basal ganglia or thalamic (left- or right-sided) lesions. Results suggest that damage to biogenic amine pathways and/or frontocaudate projections may play an important role in the modulation of mood.     

Abnormalities of copper in Gilles de la Tourette syndrome

The Gilles de la Tourette syndrome is a disorder whose etiology and pathogenesis are little understood. The number of biochemical abnormalities described in this disorder is minimal. Ten of a total of 80 patients were found to have an abnormally low serum copper. A report is presented on two patients who consented to further detailed investigation and in whom copper radioisotope studies were carried out. Both exhibited abnormalities of copper handling, in that we observed an abnormally fast disappearance of copper from the plasma and an abnormally slow uptake by the liver. The rates of intestinal absorption and urinary excretion were normal. We did not identify an abnormal site of sequestration of the metal in the body.     

Urinary and fecal excretions and absorption of a large supplement of selenium: superiority of selenate over selenite

A correction needs to be made to the form of selenium used in earlier studies; what was believed to be selenite-Se in solution is now known to have been selenate-Se. In the present study, excretion of Se was followed in 13 women after ingestion of 1 mg Se as selenite or selenate in solution. Fecal excretion of selenate-Se was less than for selenite-Se reflecting a higher apparent absorption [94 +/- 4% (SD), 62 +/- 14%, respectively]. Peak excretion of Se occurred 3 h earlier for selenate-Se than for selenite-Se and was 6 times higher. Total urinary excretion of selenate-Se was 3 times that of selenite-Se and still 2 times as high when expressed as % absorbed dose. Total recovery of Se in urine and feces was similar for both forms. There was remarkable agreement between these results and those reported earlier for selenate-Se (Selovet-1) and selenite-Se.     

Alcohol, education and action: shifting emphases

Over the past 20 years there has not only been a substantialincrease in indicators of alcoholrelated harm, but also an increasein professional and public awareness of alcohol problems andthe need to prevent them. Sadly, however, much of this awarenessof the need for prevention has resulted in little more thanrather desultory calls for more education. From my ‘pointof view’ it is time to shift further some of the emphasesin the debate aboust alcohol, education and action.     

Spatial distribution of twitch and tonic fibres in a snake muscle one myofibre thick

The spatial distribution of twitch and tonic fibres in a snake muscle one myofibre thick (ventral costocutaneous) has been investigated. It was found that small groups of like fibres were favoured at the expense of larger groups when compared with sequences generated by a computer in which fibres were distributed randomly. The number of times that like fibres occurred next to one another was used as another measure of their spatial distribution. The number of adjacencies of like fibres was less than the expected number of adjacencies determined both by random sequences and by probability theory. The expected number of adjacencies determined by means of random sequences and a priori probability theory were almost identical. This dispersion of like fibres may reflect processes that occur during muscle development and may have functional implications.     

The pathologist's examination of the "lumpectomy"--the pathologists' view of surgical margins.

Despite the widespread conservative management of breast cancer, the pathologists' examination of these specimens is far from uniform. Pathologists sample margins differently, and even disagree on what constitutes a positive margin. This variability in the pathologic examination of the lumpectomy creates tremendous problems in analyzing the existing literature on the importance of positive margins. Herein is a discussion of the available data on the significance of margin assessment. We furthermore suggest a practical approach to examining margins with an emphasis on a functional orientation of the specimen with respect to the nipple. Only by adopting a uniform system of margin assessment can we begin to critically evaluate the importance of positive margins in segmental resections of the breast.