Comparison of dynamic and step-and-shoot intensity-modulated radiation therapy planning and delivery.

Intensity-modulated radiation therapy (IMRT) is commonly delivered using the dynamic or segmental mode of multileaf collimators (DMLC or SMLC). Both methods are designed to deliver intensity-modulated beams as determined by inverse planning software. In this study, we have used the Helios IMRT planning system to generate ideal treatment plans for 10 cases of 2 common treatment sites (prostate and head and neck) and have investigated the actual treatment fluence distributions generated for each of the MLC leaf motion choices. The 2 dose delivery techniques were dosimetrically compared to each other and to the treatment plans. For each technique, point doses were measured in a water phantom using ionization chambers. Also for each technique, 2-dimensional dose distributions at a selected depth in a plastic phantom were obtained, using extended range film. The total delivery time and the number of monitor units (MU) delivered by each method were also compared. Our results indicate that the 2 delivery methods produce comparable results dosimetrically. For the cases reviewed, the delivery time was an average of 15% longer for SMLC deliveries, while the number of MUs (beam-on time) required by SMLC was an average of 15% fewer, than that for the DMLC. In the interest of simplicity, lower beam-on time, and potentially fewer mechanically-related problems, we think that the SMLC delivery technique may be the better choice when Helios is used for planning and Varian linear accelerators are used for delivery.     

Measurement of the dose deposition characteristics of x-ray fluoroscopy beams in water

The purpose of this study was to characterize the x-ray dose distribution of fluoroscopy beams by measuring their percent depth dose curves and lateral dose profiles in a water phantom. Percent depth dose curves were measured near the surface with an Attix parallel plate chamber and deep within the water phantom with a Farmer-type cylindrical chamber. Percent depth dose curves were compared to published data where applicable. Lateral dose profiles were measured at depths of 2, 5, 10, and 15 cm in phantom with a Farmer chamber. Pulsed, 50 mA x-ray beams with peak tube potentials of 60, 80, 100, and 120 kV and half value layers of 1.89, 2.52, 3.20, and 4.09 mm Al, respectively, were investigated.     

Daily running promotes spatial learning and memory in rats.

Previous studies on exercise have shown that physical activity improves learning and memory. Present study was performed to determine the effects of acute, chronic and continuous exercise with different periods on spatial learning and memory recorded as the latency and length of swim path in the Morris water maze testing in subsequent 8 days. Four rat groups were included as follows: (1) group C, controls which did not exercise; (2) group A, 30 days treadmill running before and 8 days during the Morris water maze testing period; (3) group B, 30 days exercise before the Morris water maze testing period only; (4) group D, 8 days exercise only during the Morris water maze testing period. The results showed that chronic (30 days) and continuous (during 8 days of Morris water maze testing days) treadmill training produced a significant enhancement in spatial learning and memory which was indicated by decreases in path length and latency to reach the platform in the Morris water maze test (p<0.05). The benefits in these tests were lost in 3 days, if the daily running session was abandoned. In group D with acute treadmill running (8 days exercise only) the difference between the group A disappeared in 1 week and benefit seemed to be obtained in comparison with the controls without running program. In conclusion the chronic and daily running exercises promoted learning and memory in Morris water maze, but the benefits were lost in few days without daily running sessions in adult rats.     

International participation in major intensive care journals

Objective

This study seeks to assess the scientific contributions in the field of intensive care medicine from each of the major countries (per million inhabitants) and discusses the possible factors which may contribute to any differences.

Data source

Review of scientific journals.

Study selection

We examined the total number of published papers (between 1989 and 1993) in five major respiratory and intensive care journals:Intensive Care Medicine, Critical Care Medicine, Chest, The American Review of Respiratory Disease, andCirculatory Shock.

Data synthesis

Amongst the American journals, USA and Canada were the predominant contributors followed by the other countries in the following order: Switzerland, Sweden, Belgium, the Netherlands, Finland, Austria, Denmark, UK, France, Spain, Italy, Norway, Japan and Germany.

Conclusions

The present study reveals that the smaller European nations have a greater participation than the larger European nations in the major intensive care journals. This phenomenon could be due to different submission practices in these countries compared with the larger European countries, where a considerable number of papers are submitted to local renowned journals. There was no absolute correlation between a nation's gross national product and the total number of publications.     

Inhibition of Staphylococcus Aureus Mediated by Extracts from Iranian Plants

In order to find new antibacterial agents effective against Staphylococcus aureus, ethanolic extracts of 10 plants were tested. S. aureus (489 samples) were isolated either from healthy carriers (nose and throat) or clinical samples. Out of 489 isolates tested, 98.6% were sensitive to trimethoprim-sulfamethoxazole which was used as the reference antibiotic. From the plant extracts screened for antibacterial activity, Myrtus communis L. (leaves) had the greatest activity, inhibiting the growth of 99% of the isolates. Glycyrrhiza glabra L., Eucalyptus globolus Labill and Menta viridis L., were also active against the isolates inhibiting the growth of 90, 59.5 and 48.7% of the isolates, respectively. All of these extracts were active against the reference strains of S. aureus tested. Saturia hortensis L., Teucrium polium L., and Achillea santolina L., had very little antibacterial activity, while Trigonella foenum graecum L., Echium amoenum Fisch & Mey (flowers) and Juglans regia L. (leaves), had no antibacterial activity against the bacterial isolates.     

Association of Metacognitive Beliefs,Obsessive Beliefs and Symptom Severity With Quality of Life in Obsessive–Compulsive Patients

The aim of this study was to evaluate the association of obsessive beliefs, obsessive–compulsive disorder severity and metacognitive beliefs to the quality of life in patients with obsessive–compulsive disorder (OCD). Sixty one adults with a principal diagnosis of OCD were recruited for the study. Participants were assessed by trained clinicians using an unstructured clinical interview, the Obsessive Beliefs Questionnaire, the Yale–Brown Obsessive–Compulsive Scale, the Metacognitive Beliefs Questionnaire and the WHO Quality of Life Questionnaire. Data were analyzed using Pearson's of correlation coefficients and multiple regression analyses. Findings indicate that obsessive beliefs, severity total OCD and metacognitive beliefs were associated with total quality of life scores. Regression analysis revealed that while OCD total severity explained 40.1% of the variance in total quality of life, obsessive beliefs (perfectionism/certainty domain) and metacognitions (cognitive self-consciousness and negative beliefs about thoughts in general) explained an additional 13.7%, 7.7% and 5.4% of the variance in QoL. Findings indicate that the metacognitive beliefs associated with OCD symptom severity are different from that associated with quality of life. The implications are that metacognitive therapy aimed at symptom reduction may not necessarily result in improved QoL in OCD patients.