The Radiation Therapy Oncology Group: an update of clinical research activities

This paper provides an introduction into the clinical activities of the RTOG (Radiation Therapy Oncology Group), its goals, its organization, its format for protocol development, and presents major areas of achievement. It provides an organizational chart of the group, a disease site modality cross-reference for protocols, and appendices which provide the key published results of the Group's clinical activities. This paper presents an important overview of the RTOG clinical research activities, which are designed to improve the role of radiation therapy.     

A conceptual explanation of risk-reduction behavior and intervention development

This study used a new conceptual model of health behavior to examine a specific risk-reduction response. Known to be at risk for fetal abnormalities because of maternal age, 203 women were examined for their acceptance or rejection of an amniocentesis test on the basis of individual characteristics and external significant factors. The multivariate approach to analysis offered a fuller explanation for nonuse of prenatal diagnosis than was previously available. In addition to specific client factors, environmental factors such as financial support for the procedure, multiple information sources, social support, and aspects of the client-provider interaction were determined to be important in explaining client acceptance or rejection of the test. More importantly, the study demonstrated the advantages of using a conceptual model to direct the development of interventions.     

The intragroup conflict scale: development and psychometric properties

Managers in health care organizations spend an average of 20% of their time dealing with conflict. Hence, a well-developed measure of intragroup conflict is needed to assess work environments. The Intragroup Conflict Scale was developed to measure views of conflict, perceptions of behavior, and perceptions of affective states, that occur in the core process of conflict. The scale was pilot tested with a sample of 184 staff nurses and was later used in a study of antecedents and effects of intragroup conflict in the nursing unit (n = 141). Data from the two studies were merged (n = 325). Using PCA with varimax rotation in the analysis of merged data, three factors that explained 69.2% of variance were extracted. Factor 1 reflects opposition processes and negative emotion; factor 2 reflects trust and freedom of expression; and factor 3 reflects views of conflict. Factor loadings ranged from .60 to .88 on factor 1, from .62 to .79 on factor 2, and from .69 to .80 on factor 3. Coefficient alpha for the three factors were .89 for factor 1, .88 for factor 2, and .79 for factor 3. Correlations with existing scales provided support for construct validity. The scale has evidence for its reliability and validity, and may have the potential to contribute to the understanding of intragroup conflict in organizations. The new Intragroup Conflict Scale demonstrates sufficient construct validity to warrant its continued evaluation.     

Gastric adenocarcinoma in a patient with common variable immunodeficiency

We describe a 46-year-old man with a 20-year history of common variable immunodeficiency (CVID) who developed adenocarcinoma of the stomach. Although the mechanism is still debated, there is an increased frequency of gastric adenocarcinoma of the stomach in patients with CVID. Consequently, gastric complaints in patients with CVID should be pursued aggressively.     

Relationships between hyperglycemia and cognitive performance among adults with type 1 and type 2 diabetes

OBJECTIVE: Hyperglycemia is a common event among patients with type 1 and type 2 diabetes. While the cognitive-motor slowing associated with hypoglycemia is well documented, the acute effects of hyperglycemia have not been studied extensively, despite patients' reports of negative effects. This study prospectively and objectively assessed the effects of hyperglycemia on cognitive-motor functioning in subjects' natural environment. RESEARCH DESIGN AND METHODS: Study 1 investigated 105 adults with type 1 diabetes (mean age 37 years and mean duration of diabetes 20 years), study 2 investigated 36 adults with type 2 diabetes (mean age 50 years and mean duration of diabetes 10 years), and study 3 investigated 91 adults with type 1 diabetes (mean age 39 years and mean duration of diabetes 20 years). Subjects used a hand-held computer for 70 trials over 4 weeks, which required them to complete various cognitive-motor tasks and then measure and enter their current blood glucose reading. RESULTS: Hyperglycemia (blood glucose >15 mmol/l) was associated with slowing of all cognitive performance tests (P < 0.02) and an increased number of mental subtraction errors for both type 1 and type 2 diabetic subjects. The effects of hyperglycemia were highly individualized, impacting approximately 50% of the subjects. CONCLUSIONS: Acute hyperglycemia is not a benign event for many individuals with diabetes, but it is associated with mild cognitive dysfunction.     

Cellular immune selection with hepatitis C virus persistence in humans

Hepatitis C virus (HCV) infection frequently persists despite substantial virus-specific cellular immune responses. To determine if immunologically driven sequence variation occurs with HCV persistence, we coordinately analyzed sequence evolution and CD8+ T cell responses to epitopes covering the entire HCV polyprotein in subjects who were followed prospectively from before infection to beyond the first year. There were no substitutions in T cell epitopes for a year after infection in a subject who cleared viremia. In contrast, in subjects with persistent viremia and detectable T cell responses, we observed substitutions in 69% of T cell epitopes, and every subject had a substitution in at least one epitope. In addition, amino acid substitutions occurred 13-fold more often within than outside T cell epitopes (P < 0.001, range 5-38). T lymphocyte recognition of 8 of 10 mutant peptides was markedly reduced compared with the initial sequence, indicating viral escape. Of 16 nonenvelope substitutions that occurred outside of known T cell epitopes, 8 represented conversion to consensus (P = 0.015). These findings reveal two distinct mechanisms of sequence evolution involved in HCV persistence: viral escape from CD8+ T cell responses and optimization of replicative capacity.     

Effect of air and heliox as carrier gas on CO2 transport in a model of high-frequency oscillation comparing two oscillators

OBJECTIVE: To study the effect of carrier gas on CO(2) transport during high-frequency oscillatory ventilation in a closed model. DESIGN: In vitro model study. SETTING: Respiratory research laboratory affiliated with a tertiary center for pediatric critical care. SUBJECT: In vitro, closed-lung model consisting of a glass tube (9.8 x 1000 mm) covered at each end with balloons. INTERVENTION: Air or heliox (80:20) at constant pressure was oscillated inside the model, comparing the Sensormedics 3100A and Hummingbird BMO-20N oscillators at equal amplitude. MEASUREMENTS AND MAIN RESULTS: Tracer gas (CO(2)) was injected at one end of the model, and CO(2) concentration was measured at the opposite end. Speed of CO(2) transport was expressed as the time for the CO(2) concentration to reach 63% of the final concentration (the time constant). In room air, using the Hummingbird oscillator and increasing frequency stepwise from 5 to 20 Hz, the time constant decreased from 2813 to 457 secs (p =.05). Using the Sensormedics oscillator in room air at increasing frequency from 5 to 15 Hz, the time constant decreased from 1584 to 551 secs (p =.05). In heliox, using the Hummingbird oscillator, the speed of CO(2) transport increased by 85% (p =.029) at 5 Hz and by 28% (p =.05) at 15 Hz. With the Sensormedics oscillator using heliox, the speed of CO(2) transport increased by 16% at 5 Hz (p =.009) and 52% at 15 Hz (p =.008). Proportionally, the increase in CO(2) transport with heliox was greater at 5 Hz for the Hummingbird oscillator and at 15 Hz for the Sensormedics oscillator. CONCLUSIONS: In a closed model, we showed that during high-frequency oscillatory ventilation in room air, CO(2) transport increases with increasing frequency for both ventilators. Using heliox as carrier gas significantly augmented CO(2) transport, but the increase is frequency and device dependent. The effect of heliox on oscillator performance and the clinical applicability of our findings require further study.     

Methanol fixation. An alternative to heat fixation of smears before staining

Methanol fixation of Gram-stained smears was compared to heat fixation. Smears were prepared in duplicate from direct clinical specimens, blood culture bottles, and bacterial colonies. Results from this study show that methanol fixation is superior in every instance to heat fixation. The morphology of bacteria and tissue cells was not distorted, little or no background debris was observed, and a better Gram reaction was noted.