The logarithmic transformation and the geometric mean in reporting experimental IgE results: what are they and when and why to use them?

BACKGROUND: Immunologic data, such as IgE and interleukin 4, tend to have positively skewed distributions with a long tail of larger values. This renders analyses based on normal distribution theory questionable (eg, t tests and analysis of variance) and distorts the sample mean as a measure of central tendency. These problems can be addressed through analysis of log-transformed data. Data analyzed in this fashion are summarized with the geometric mean. OBJECTIVE: To elucidate the use of the logarithmic transform and the geometric mean in the analysis of immunologic data. METHODS: The analysis may be conducted by transforming the data to a logarithmic scale to achieve a bell-shaped (approximately normal) distribution. The bell-shaped distribution needed to validate statistical inferences is only achieved in the transformed scale. In summarizing the research findings, the statistical analyst usually will transform means and confidence intervals from the logarithmic scale back to the original scale of measurement. Statistical inferences in the log scale remain valid for the data. The result of back transforming the mean of logarithmic values to the original scale is the geometric mean. This statistic is less subject to distortion by the unusually large values in the tail of the positively skewed distribution of the data. RESULTS: A brief example is used to illustrate this type of analysis. Conclusions: Logarithmic transformation permits valid statistical inference for positively skewed immunologic data. A result of this analysis is the geometric mean, which is a better measure of central tendency of this data type than the usual sample mean.     

Dysregulation of insulin receptor substrate 2 in beta cells and brain causes obesity and diabetes

The molecular link between obesity and beta cell failure that causes diabetes is difficult to establish. Here we show that a conditional knockout of insulin receptor substrate 2 (Irs2) in mouse pancreas beta cells and parts of the brain--including the hypothalamus--increased appetite, lean and fat body mass, linear growth, and insulin resistance that progressed to diabetes. Diabetes resolved when the mice were between 6 and 10 months of age: functional beta cells expressing Irs2 repopulated the pancreas, restoring sufficient beta cell function to compensate for insulin resistance in the obese mice. Thus, Irs2 signaling promotes regeneration of adult beta cells and central control of nutrient homeostasis, which can prevent obesity and diabetes in mice.     

A phase II trial of olanzapine,dexamethasone, and palonosetron for the prevention of chemotherapy-induced nausea and vomiting: a Hoosier oncology group study

Objective The purpose of this study is to determine the control of acute and delayed chemotherapy-induced nausea and vomiting (CINV) in patients receiving moderately emetogenic chemotherapy (MEC) and highly emetogenic chemotherapy (HEC) with the combined use of palonosetron and olanzapine, and dexamethasone with the dexamethasone given on day 1 only. Materials and methods Forty chemotherapy-naive patients received on the day of chemotherapy, day 1, an anti-emetic regimen consisting of dexamethasone, palonosetron, and olanzapine. Patients continued olanzapine for days 2–4 after chemotherapy administration. Patients recorded daily episodes of emesis, daily symptoms utilizing the M.D. Anderson Symptom Inventory, and the utilization of rescue therapy. Results For the first cycle of chemotherapy, the complete response (no emesis, no rescue) for the acute period (24 h post-chemotherapy) was 100%, the delayed period (days 2–5 post-chemotherapy) 75%, and the overall period (0 120 h post-chemotherapy) 75% in 8 patients receiving HEC and was 97, 75, and 72% in 32 patients receiving MEC. Patients with no nausea for the acute period was 100%, the delayed period 50%, and the overall period 50% in 8 patients receiving HEC and was 100, 78, and 78% in 32 patients receiving MEC. Discussion The complete response and control of nausea in subsequent cycles of chemotherapy were not significantly different from cycle one. Conclusion Olanzapine combined with a single dose of dexamethasone and a single dose of palonosetron was very effective in controlling acute and delayed CINV in patients receiving both HEC and MEC.     

Cohesion among nurses: a comparison of bedside vs. charge nurses' perceptions in Australian hospitals

AIM: This study examines the extent to which hospital nurses view their working environment in a positive sense, working as a cohesive group. BACKGROUND: Despite the fact that nursing in Australia is now considered a profession, it has been claimed that nurses are an oppressed group who use horizontal violence, bullying and aggression in their interactions with one and other. METHODS: After ethical approval, a random sample of 666 nurses working directly with patients and all 333 critical care nurses employed in three large tertiary Australian hospitals were invited to participate in the study in the late 1990s. A mailed survey examined the perceptions of interaction nurses had with each other. The hypothesis, that level of employment (either Level I bedside nurses or Level II/III clinical leaders) and area of work (either critical care or noncritical care) would influence perceptions of cohesion, as measured by the cohesion amongst nurses scale (CANS) was tested. RESULTS: In total 555 (56%) surveys were returned. Of these, 413 were returned by Level I and 142 by Level II/III nurses. Of this sample, 189 were critical care and 355 noncritical care nurses. There was no difference between Level I and II/III nurses in mean CANS scores. It is interesting to note that the item rated most positively was "nurses on the units worked well together", however, the item rated least positive was "staff can be really bitchy towards each other" for both Level I and II/III nurses. There was no difference in CANS scores between critical care and noncritical care nurses. CONCLUSIONS: Nurses working in Australian hospitals perceived themselves to be moderately cohesive but, as would be expected in other work settings, some negative perceptions existed.     

Biliary tract obstruction in chronic pancreatitis

Bile duct strictures are a common complication in patients with advanced chronic pancreatitis and have a variable clinical presentation ranging from an incidental finding to overt jaundice and cholangitis. The diagnosis is mostly made during investigations for abdominal pain but jaundice may be the initial clinical presentation. The jaundice is typically transient but may be recurrent with a small risk of secondary biliary cirrhosis in longstanding cases. The management of a bile duct stricture is conservative in patients in whom it is an incidental finding as the risk of secondary biliary cirrhosis is negligible. Initial conservative treatment is advised in patients who present with jaundice as most will resolve once the acute on chronic attack has subsided. A surgical biliary drainage is indicated when there is persistent jaundice for more than one month or if complicated by secondary gallstones or cholangitis. The biliary drainage procedure of choice is a choledocho-jejunostomy which may be combined with a pancreaticojejunostomy in patients who have associated pain. Since many patients with chronic pancreatitis have an inflammatory mass in the head of the pancreas, a Frey procedure is indicated but a resection should be performed when there is concern about a malignancy. Temporary endoscopic stenting is reserved for cholangitis while an expandable metal stent may be indicated in patients with severe co-morbid disease.     

Does childhood sexual abuse have an effect on young adults' nicotine disorder (dependence or withdrawal)? Evidence from a birth cohort study

AIMS: To examine whether there is evidence of an independent association between childhood sexual abuse (CSA) and nicotine disorder in youth and to explore the mechanisms underlying this association in a prospective cohort study. DESIGN: Birth cohort study followed-up to 21 years. SETTING: One of two major obstetric hospitals in Brisbane, Australia. PARTICIPANTS: The Mater-University of Queensland Study of Pregnancy involves a prospective birth cohort from a population-based sample involving 7223 singletons whose mothers were enrolled between 1981 and 1984 at the first antenatal visit. The present cohort consisted of a subgroup of 2571 youth who completed the life-time version of the Composite International Diagnostic Interview--computerized version (CIDI-Auto) at the 21-year follow-up. MEASUREMENTS: Nicotine disorder was measured based on Diagnostic and Statistical Manual version IV (DSM-IV) diagnostic criteria and measures of CSA, including retrospective self-reports of rape, were obtained at 21 years. Results Of 2571 young adults, 16.6% met the criteria for either dependence (12.8%) or withdrawal (8.5%). Non-penetrative sexual abuse was reported by 15.5% of respondents and 8.0% reported penetrative sexual abuse. For any types of sexual abuse including non-penetrative, penetrative and self-reported rape before age 16 years, young adults had significantly higher rates of nicotine disorder than young adults who did not experience CSA. This relationship was independent and appeared direct after adjustment for a range of potential confounding and mediating factors. CONCLUSIONS: This study shows that CSA is associated with young adult nicotine disorder. The results extend the public health significance of findings in this area and highlight the importance of not only intensifying public health efforts to address substance use problems among those who have experienced CSA, but of early intervention, so that emerging risky behaviours may be targeted in the earliest stages.