Taking the beat of the Arctic: are lemming population cycles changing due to winter climate?

Reports of fading vole and lemming population cycles and persisting low populations in some parts of the Arctic have raised concerns about the spread of these fundamental changes to tundra food web dynamics. By compiling 24 unique time series of lemming population fluctuations across the circumpolar region, we show that virtually all populations displayed alternating periods of cyclic/non-cyclic fluctuations over the past four decades. Cyclic patterns were detected 55% of the time (n = 649 years pooled across sites) with a median periodicity of 3.7 years, and non-cyclic periods were not more frequent in recent years. Overall, there was an indication for a negative effect of warm spells occurring during the snow onset period of the preceding year on lemming abundance. However, winter duration or early winter climatic conditions did not differ on average between cyclic and non-cyclic periods. Analysis of the time series shows that there is presently no Arctic-wide collapse of lemming cycles, even though cycles have been sporadic at most sites during the last decades. Although non-stationary dynamics appears a common feature of lemming populations also in the past, continued warming in early winter may decrease the frequency of periodic irruptions with negative consequences for tundra ecosystems.

The influence of age, sex and cardiorespiratory fitness on maximal fat oxidation rate

Fat oxidation decreases with age, yet no studies have previously investigated if aging affects the maximal fat oxidation rate (MFO) during exercise in men and women differently. We hypothesized that increased age would be associated with a decline in MFO and this would be more pronounced in women due to menopause, compared with men. In this cross-sectional study design, 435 (247/188, male/female) subjects of varying ages performed a DXA scan, a submaximal graded exercise test and a maximal oxygen uptake test, to measure MFO and cardiorespiratory fitness (CRF) by indirect calorimetry. Subjects were stratified into 12 groups according to sex (male/female), age (<45, 45-55 and >55 years), CRF (below average and above average). Women aged <45 years had a higher MFO relative to fat free mass (FFM) (mg/min/kg) compared with men, regardless of CRF. However, there were no differences in MFO (mg/min/kg FFM) between men and women, in the groups aged between 45-55 and >55 years. In summary, we found that women aged <45 years display a higher MFO (mg/min/kg FFM) compared with men and that this sexual divergence is abolished after the age of 45 years. Novelty: Maximal fat oxidation rate is higher in young women compared with men. This sex-related difference is attenuated after the age of 45 years. Cardiorespiratory fitness does not influence this sex-related difference.

Documenting lemming population change in the Arctic: Can we detect trends?

Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.

Correction to: Documenting lemming population change in the Arctic: Can we detect trends?

In the original published article, some of the symbols in figure 1A were modified incorrectly during the typesetting and publication process. The correct version of the figure is provided in this correction.

Abstract P3-12-08: Are different therapeutic approaches required after skin and nipple sparing mastectomies for locoregional control? A single institution's experience

Introduction

Nipple sparing (NSM) and skin sparing (SSM) mastectomies are gaining popularity. These procedures leave breast tissue at the skin/breast interface with the intent to better cosmesis. However, the impact of NSM versus SSM on risk of local recurrence in the remaining breast tissue is not well characterized, nor is the effect of post mastectomy radiotherapy (PMRT) in these patients.

Methods

A single institution retrospective study was conducted on women treated with NSM or SSM from 2005 to 2011 with follow up through 2015. Chest wall and chest wall or axillary recurrence were assessed. Factors associated with recurrence were examined. Kaplan Meier estimates and Cox proportional hazards models were used to analyze chest wall recurrence (CWR) and chest wall or axillary recurrence (CWAR), with CWAR as the primary outcome variable.

Results

This analysis identified 181 women who underwent a SSM (n=103, 58 (56%) with PMRT) or NSM (n=78, 35 (45%) with PMRT). Women undergoing SSM were older (56.0 ± 13.6 years, mean ± SD) than NSM (44.6 ± 11.3, p &lt;0.0001) while follow-up times were similar (4.91 ± 0.43 and 5.43 ± 0.27 respectively, p = 0.15). Women undergoing PMRT were younger (49.2 ± 13.6 vs 53.1 ± 13.9 years, p = 0.008) but more likely to present with lymphovascular space invasion (LVSI)(42% vs 16%, p = 0.0003 by Chi-square), and were more likely to receive chemotherapy (83% vs 47%, p &lt;0.0001). The majority of women (62%) in the group not receiving PMRT had stage I disease, and 79% were node negative. For those undergoing PMRT, 83% were stage II or III, and 69% were node positive (p &lt;0.0001 for both differences). Despite the higher apparent risk of the PMRT group, the total number of chest wall or axillary recurrences was similar (8 in PMRT, 6 in no PMRT). Event-free survival for CWAR at 5 years was 92% for PMRT and 96% for no PMRT (p=0.42) and at 7.5 years, 85% and 84% respectively (p=0.42). In univariate Cox regression among all patients, age was the strongest predictor of CWAR (HR = 1.103 per year of age, 95% CI 1.053-1.154, p&lt;0.0001). CWAR occurred in 2.6 % of NSM patients as compared with 11.8% of SSM patients (p=0.025 by Fisher's exact test). SSM versus NSM was associated with increased hazzard for CWAR with HR = 4.6 (95% CI 1.03-21, p=0.046) on univariate analysis. However, this apparent risk became non-significant (HR = 2.24, 95% CI 0.48 – 10.5) with adjustment for age. Other variables associated with CWAR on univariate analysis included receipt of chemotherapy (HR = 0.28, 0.09-0.86, p=0.027) and estrogen receptor positive status (HR = 0.34, 0.12-0.98, p=0.046) but these also became non-significant with adjustment for age. In multivariate Cox regression analysis, use of PMRT was associated with a non-significant higher risk of CWAR (HR = 1.45, 0.33-6.4, p=0.63 ) adjusting for age, LVSI, mastectomy type, stage, and ER status.

Conclusions

The risk of a chest wall or axillary recurrence for early stage breast cancer after a SSM or NSM appears to be low at five years. Radiation can likely be omitted in this group. Furthermore, despite presenting with more advanced disease, women who underwent PMRT experienced excellent locoregional control. Further research is needed on this topic.

Citation Format: Hopkins ZH, Frandsen J, Poruk KE, Agarwal J, Poppe MM. Are different therapeutic approaches required after skin and nipple sparing mastectomies for locoregional control? A single institution's experience. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-08.

Plasma brain-derived neurotrophic factor and prefrontal white matter integrity in late-onset depression and normal aging

OBJECTIVE

To explore the relationship between brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), cerebral deep white matter lesions (DWMLs), and measures of white matter integrity in patients with late-onset depression, with respect to vascular risk factors.

METHOD

We examined 22 patients with late-onset depression and 22 matched controls. Quantification of plasma BDNF and VEGF levels were performed with enzyme-linked immunosorbent assay (ELISA) kits. Measures of white matter integrity comprised apparent diffusion coefficient (ADC) and fractional anisotropy (FA), obtained by diffusion tensor imaging (DTI). Effects of DWMLs, FA, ADC, and vascular risk factors on BDNF and VEGF were assessed using multiple linear regression.

RESULTS

The BDNF and VEGF levels did not differ significantly between groups. With pooled data for patients and controls, the BDNF level was positively associated with both number (t = 2.14, P = 0.039) and volume (t = 2.04, P = 0.048) of prefrontal DWMLs and negatively associated with FA in prefrontal normal-appearing white matter (t = -2.40, P = 0.02), adjusted for age and gender. Smoking and hypercholesterolemia was positively associated with the BDNF (t = 2.36, P = 0.023) and VEGF levels (t = 2.28, P = 0.028), respectively.

CONCLUSION

Our results suggest a role for BDNF in the complex pathophysiologic mechanisms underlying DWMLs in both normal aging and late-onset depression.

Localization of white-matter lesions and effect of vascular risk factors in late-onset major depression

BACKGROUND

Several studies suggest that patients with late-onset major depression (MD) have an increased load of cerebral white-matter lesions (WMLs) compared with age-matched controls. Vascular risk factors such as hypertension and smoking may confound such findings. Our aim was to investigate the association between the localization and load of WMLs in late-onset MD with respect to vascular risk factors.

METHOD

We examined 22 consecutive patients with late-onset first-episode MD and 22 age- and gender-matched controls using whole-brain magnetic resonance imaging (MRI). The localization, number and volume of WMLs were compared between patients and controls, while testing the effect of vascular risk factors.

RESULTS

Among subjects with one or more WMLs, patients displayed a significantly higher WML density in two white-matter tracts: the left superior longitudinal fasciculus and the right frontal projections of the corpus callosum. These tracts are part of circuitries essential for cognitive and emotional functions. Analyses revealed no significant difference in the total number and volume of WMLs between groups. Patients and controls showed no difference in vascular risk factors, except for smoking. Lesion load was highly correlated with smoking.

CONCLUSIONS

Our results indicate that lesion localization rather than lesion load differs between patients with late-onset MD and controls. Increased lesion density in regions associated with cognitive and emotional functions may be crucial in late-onset MD, and vascular risk factors such as smoking may play an important role in the pathophysiology of late-onset MD, consistent with the vascular depression hypothesis.

Dynamic changes in corticospinal tracts after stroke detected by fibretracking

BACKGROUND AND AIMS

The integrity of motor pathways and functional connectivity patterns are important in assessing plastic changes related to successful recovery, to obtain prognostic information and to monitor future therapeutic strategies of stroke patients. We tested the following hypotheses: (1) that changes in axonal integrity along the corticospinal tract after stroke can be detected as a reduction in fractional anisotropy; and (2) that sustained low fractional anisotropy is indicative of axonal loss and therefore is correlated with poor motor outcome, as measured by specific neurological motor scores.

METHODS

We developed a segmentation tool based on magnetic resonance diffusion tensor imaging in conjunction with three dimensional fibretracking for longitudinal studies of the corticospinal tract, and used specific neurological motor scores to test the hypotheses in five stroke patients within the first week and 30 and 90 days after the stroke.

RESULTS

Reduction in fractional anisotropy within the first weeks after stroke reflected a decline in axonal integrity, leading to Wallerian degeneration, and demonstrated a correlation between the temporal evolution of fractional anisotropy and motor function in patients with poor motor outcome.

CONCLUSION

The study demonstrated the feasibility of fibretracking as a segmentation tool for mapping distal parts of the corticospinal motor pathways and showed that fractional anisotropy in the segmented corticospinal tract is a sensitive measure of structural changes after stroke.

Steroid reversibility test followed by inhaled budesonide or placebo in outpatients with stable chronic obstructive pulmonary disease. The Danish Society of Respiratory Medicine

The aim of this study was evaluate the predictive value of a 2 week course of prednisolone on the effect of 6 months treatment with inhaled budesonide in patients with stable chronic obstructive pulmonary disease (COPD). Forty patients with stable COPD entered the study, and received prednisolone (37.5 mg o.d.) for 2 weeks. They were subsequently divided into steroid-irreversible and steroid-irreversible, using 15% of baseline as a dividing point. In each group patients were randomized to receive budesonide 400 micrograms b.i.d. or placebo for 6 months. During treatment with prednisolone, three patients dropped out because of side effects. Of the remaining 37, only two patients (5%) were reversible with prednisolone forced expiratory volume in 1s [(FEV1) > 15% of baseline], and among the steroid-irreversible, 26 patients were evaluated after 6 months treatment with either placebo or budesonide. No significant differences in spirometry values, symptoms, or number of exacerbations were found between these two groups. Reversibility with prednisolone is rarely seen in COPD. In outpatients with stable COPD and no signs of asthma or atopy, 2 weeks treatment with prednisolone seems to be of no value in choosing subsequent long-term therapy.

Long term follow up of patients who underwent jejunoileal bypass for morbid obesity

OBJECTIVE

To describe our long term results after jejunoileal (JI) bypass for morbid obesity.

DESIGN

Retrospective study.

SETTING

Teaching hospital, Denmark

SUBJECTS

All 57 patients who underwent JI bypass for morbid obesity between January 1973 and December 1988.

INTERVENTIONS

Type A and type B JI bypass.

MAIN OUTCOME MEASURES

Weight loss, operative morbidity and mortality, and subjective evaluation of the results.

RESULTS

Mean duration of follow up was 15.9 years (range 8-22). There were no operative or early postoperative deaths, but there were 7 late deaths (12%). 5 patients developed postoperative complications (9%), and 11 patients (19%) required reoperation for side effects or complications. The mean body mass index (BMI, kg/m2) was reduced from 47.5 (range 40-60) to 32 (range 22-49) during the follow up period which corresponded to a weight loss of about 42 kg. Of the 39 patients who still had a JI bypass in 1994, nearly two thirds said that they were satisfied with the operation, though they nearly all had some side effects such as diarrhoea or intermittent abdominal pain.

CONCLUSION

As complications of JI bypass can develop at any time, we suggest that all patients who have had the operation should be regularly followed up at special clinics so that complications can be diagnosed and treated as soon as possible.

Amiodarone during pregnancy

A case study is presented in which amiodarone (A) was given during the whole of pregnancy and during the breast feeding period. An intensive observation of thyroid tests, serum concentrations of A and its metabolite, desethylamiodarone (DEA) was undertaken. The child was observed in the same way from birth until 2 months of age. The milk was analyzed for A and DEA. As reported in other published cases, transplacental passage was found and there was a relatively high concentration of amiodarone in the milk. Our child like the other children was healthy at birth, being euthyroid and with no goiter or corneal deposits. No effect was observed of the medication on growth, thyroid tests or cornea. It is concluded that amiodarone can be given during pregnancy but it is advisable to use as low doses as possible and control the serum concentrations at regular intervals. Breast feeding need not be forbidden.