Antagonistic selection from predators and pathogens alters food-web structure

Selection can alter predator-prey interactions. However, whether and how complex food-webs respond to selection remain largely unknown. We show in the field that antagonistic selection from predators and pathogens on prey body-size can be a primary driver of food-web functioning. In Windermere, U.K., pike (Esox lucius, the predator) selected against small perch (Perca fluviatilis, the prey), while a perch-specific pathogen selected against large perch. The strongest selective force drove perch trait change and ultimately determined the structure of trophic interactions. Before 1976, the strength of pike-induced selection overrode the strength of pathogen-induced selection and drove a change to larger, faster growing perch. Predation-driven increase in the proportion of large, infection-vulnerable perch presumably favored the pathogen since a peak in the predation pressure in 1976 coincided with pathogen expansion and a massive perch kill. After 1976, the strength of pathogen-induced selection overrode the strength of predator-induced selection and drove a rapid change to smaller, slower growing perch. These changes made perch easier prey for pike and weaker competitors against juvenile pike, ultimately increasing juvenile pike survival and total pike numbers. Therefore, although predators and pathogens exploited the same prey in Windermere, they did not operate competitively but synergistically by driving rapid prey trait change in opposite directions. Our study empirically demonstrates that a consideration of the relative strengths and directions of multiple selective pressures is needed to fully understand community functioning in nature.     

Hepatic safety of once-monthly injectable extended-release naltrexone administered to actively drinking alcoholics

Background:  Hepatoxicity has been reported with oral naltrexone. Hepatic safety data were examined from a 6-month study evaluating the efficacy and safety of a now available extended-release formulation of naltrexone (XR-NTX) in patients with alcohol dependence.
Methods:  In all, 624 patients (68% male; median age of 44 years) were randomly assigned to XR-NTX 380 mg ( n  = 205), XR-NTX 190 mg ( n  = 210), or placebo ( n  = 209).
Results:  There were no significant differences in alanine aminotrasferase, aspartate aminotransferase, or bilirubin levels between the study groups at study initiation or at subsequent assessments. Gamma-glutamyltransferase in the XR-NTX 380 mg group was lower compared with placebo at weeks 4, 8, 12, and 20. Both high (>3 times the upper limit of normal) liver chemistry tests (LCTs) and hepatic-related adverse events were infrequent in all study groups. In patients who were drinking heavily throughout the study, obese subjects, or those taking nonsteroidal anti-inflammatory drugs, there was no increase in frequency of high LCTs or hepatic-related adverse events in patients receiving XR-NTX (either dose) compared with placebo.
Conclusion:  Extended-release formulation of naltrexone does not appear to be hepatotoxic when taken at the recommended clinical doses in actively drinking alcohol-dependent patients.     

Effects of α tocopherol and β carotene supplements on symptoms, progression, and prognosis of angina pectoris

Objective—To evaluate the effects of α tocopherol and β carotene supplements on recurrence and progression of angina symptoms, and incidence of major coronary events in men with angina pectoris.
Design—Placebo controlled clinical trial.
Setting—The Finnish α tocopherol β carotene cancer prevention study primarily undertaken to examine the effects of α tocopherol and β carotene on cancer.
Subjects—Male smokers aged 50-69 years who had angina pectoris in the Rose chest pain questionnaire at baseline (n = 1795).
Interventions—α tocopherol (vitamin E) 50 mg/day, β carotene 20 mg/day or both, or placebo in 2 × 2 factorial design.
Main outcome measures—Recurrence of angina pectoris at annual follow up visits when the questionnaire was readministered; progression from mild to severe angina; incidence of major coronary events (non-fatal myocardial infarction and fatal coronary heart disease).
Results—There were 2513 recurrences of angina pectoris during follow up (median 4 years). Compared to placebo, the odds ratios for recurrence in the active treatment groups were: α tocopherol only 1.06 (95% confidence interval (CI) 0.85 to 1.33), α tocopherol and β carotene 1.02 (0.82 to 1.27), β carotene only 1.06 (0.84 to 1.33). There were no significant differences in progression to severe angina among the groups given supplements or placebo. Altogether 314 major coronary events were observed during follow up (median 5.5 years) and the risk for them did not differ significantly among the groups given supplements or placebo.
Conclusions—There was no evidence of beneficial effects for α tocopherol or β carotene supplements in male smokers with angina pectoris, indicating no basis for therapeutic or preventive use of these agents in such patients.

Keywords: antioxidants;  angina pectoris;  prevention;  vitamin supplements     

Predictors of Atrial Fibrillation Recurrence in Hyperthyroid and Euthyroid Patients

Background

Atrial fibrillation (AF) is the most common arrhythmia in adults, and is encountered in 10-15% of the patients with hyperthyroidism. Unless euthyroidism is restored, pharmacological or electrical cardioversion is controversial in patients with AF who remain hyperthyroid.

Objective

The aim of this study was to assess the efficacy of electrical cardioversion and predictors of AF recurrence in hyperthyroid and euthyroid patients.

Methods

The study included 33 hyperthyroid (21 males) and 48 euthyroid (17 males) patients with persistent AF. The patients were sedated with intravenous midazolam before undergoing electrical cardioversion delivered by synchronized biphasic shocks. Rates of AF recurrence were recorded.

Results

Mean follow-up was 23.63 ± 3.74 months in the hyperthyroid group and 22.78 ± 3.15 months in the euthyroid group (p = 0.51). AF recurred in 14 (43.8%) and 21 (44.7%) patients in each group, respectively (p = 0.93). Multivariate regression analysis in each group showed that AF duration was the only predictor of AF recurrence, with odds ratios of 1.38 (95% confidence interval [CI] = 1.05 - 1.82, p = 0.02) in the hyperthyroid group and 1.42 (95% CI = 1.05 - 1.91, p= 0.02) in the euthyroid group.

Conclusion

Rates of long-term AF recurrence were similar in successfully cardioverted hyperthyroid and euthyroid patients. The only predictor of AF recurrence in both groups was AF duration.     

Infertility and coeliac disease.

BACKGROUND: Coeliac women may suffer from gynaecological and obstetric complications. It is possible that these complications are the first symptom of coeliac disease. AIMS: To investigate the occurrence of subclinical coeliac disease in patients with infertility or recurrent miscarriages. SUBJECTS: Women of reproductive age who were attending the hospital because of either primary or secondary infertility, or two or more miscarriages. Women undergoing sterilisation served as control subjects. METHODS: The diagnostic investigation for infertility included the endocrine status, diagnostic laparoscopy, investigation of tubal patency, postcoital test, and semen analysis of the partner. Circulating antibodies against IgA class reticulin and gliadin were used in screening for coeliac disease. In positive cases, the diagnosis was confirmed by small bowel biopsy specimens. RESULTS: Four (2.7%) of 150 women in the infertility group, and none of the 150 control subjects were found to have coeliac disease (p = 0.06). All four women with coeliac disease suffered from infertility of unexplained origin. Altogether 98 women had no discoverable reason for infertility. Thus, in this subgroup the frequency of coeliac disease was 4.1% (four of 98), the difference from the control group being statistically significant (p = 0.02). None of the coeliac women had extensive malabsorption, but two had iron deficiency anaemia. One women with coeliac disease has had a normal delivery. None of the 50 women with miscarriage had coeliac disease. CONCLUSION: Patients having fertility problems may have subclinical coeliac disease, which can be detected by serological screening tests. Silent coeliac disease should be considered in the case of women with unexplained infertility.     

A Technology-Based Quality Innovation to Identify Undiagnosed Hypertension Among Active Primary Care Patients

PURPOSE

The goal of this study was to develop a technology-based strategy to identify patients with undiagnosed hypertension in 23 primary care practices and integrate this innovation into a continuous quality improvement initiative in a large, integrated health system.

METHODS

In phase 1, we reviewed electronic health records (EHRs) using algorithms designed to identify patients at risk for undiagnosed hypertension. We then invited each at-risk patient to complete an automated office blood pressure (AOBP) protocol. In phase 2, we instituted a quality improvement process that included regular physician feedback and office-based computer alerts to evaluate at-risk patients not screened in phase 1. Study patients were observed for 24 additional months to determine rates of diagnostic resolution.

RESULTS

Of the 1,432 patients targeted for inclusion in the study, 475 completed the AOBP protocol during the 6 months of phase 1. Of the 1,033 at-risk patients who remained active during phase 2, 740 (72%) were classified by the end of the follow-up period: 361 had hypertension diagnosed, 290 had either white-coat hypertension, prehypertension, or elevated blood pressure diagnosed, and 89 had normal blood pressure. By the end of the follow-up period, 293 patients (28%) had not been classified and remained at risk for undiagnosed hypertension.

CONCLUSIONS

Our technology-based innovation identified a large number of patients at risk for undiagnosed hypertension and successfully classified the majority, including many with hypertension. This innovation has been implemented as an ongoing quality improvement initiative in our medical group and continues to improve the accuracy of diagnosis of hypertension among primary care patients.