Category: Internal Medicine - Page 12

Paradoxical Motor Recovery From a First Stroke After Induction of a Second Stroke: Reopening a Postischemic Sensitive Period

pjgrier February 8, 2016 Brain, Cardiology, Hot Topics in Research

Paradoxical Motor Recovery From a First Stroke After Induction of a Second Stroke: Reopening a Postischemic Sensitive Period
Abstract Background and objective. Prior studies have suggested that after stroke there is a time-limited period of increased responsiveness to training as a result of heightened plasticity—a sensitive period thought to be induced by ischemia itself. Using a mouse model, we have previously shown that most training-associated recovery after a caudal forelimb area (CFA) stroke occurs in the first week and is attributable to reorganization in a medial premotor area (AGm). The existence of a stroke-induced sensitive period leads to the counterintuitive prediction that a second stroke should reopen this window and promote full recovery from the first stroke. To test this prediction, we induced a second stroke in the AGm of mice with incomplete recovery after a first stroke in CFA. Methods. Mice were trained to perform a skilled prehension (reachto-grasp) task to an asymptotic level of performance, after which they underwent photocoagulation-induced stroke in CFA. After a 7-day poststroke delay, the mice were then retrained to asymptote. We then induced a second stroke in the AGm, and after only a 1-day delay, retrained the mice. Results. Recovery of prehension was incomplete when training was started after a 7-day poststroke delay and continued for 19 days. However, a second focal stroke in the AGm led to a dramatic response to 9 days of training, with full recovery to normal levels of performance. Conclusions. New ischemia can reopen a sensitive period of heightened responsiveness to training and mediate full recovery from a previous stroke.

Steven R. Zeiler, MD, PhD , Robert Hubbard , Ellen M. Gibson , Tony Zheng , Kwan Ng, MD, PhD , Richard O’Brien, MD, PhD , and John W. Krakauer, MD

Schizophrenia risk from complex variation of complement component 4

pjgrier Dementia, Hot Topics in Research, Memory Impairment

Schizophrenia risk from complex variation of complement component 4
Abstract
Schizophrenia is a heritable brain illness with unknown pathogenic mechanisms. Schizophrenia’s strongest genetic association at a population level involves variation in the major histocompatibility complex (MHC) locus, but the genes and molecular mechanisms accounting for this have been challenging to identify. Here we show that this association arises in part from many structurally diverse alleles of the complement component 4 (C4) genes. We found that these alleles generated widely varying levels of C4A and C4B expression in the brain, with each common C4 allele associating with schizophrenia in proportion to its tendency to generate greater expression of C4A. Human C4 protein localized to neuronal synapses, dendrites, axons, and cell bodies. In mice, C4 mediated synapse elimination during postnatal development. These results implicate excessive complement activity in the development of schizophrenia and may help explain the reduced numbers of synapses in the brains of individuals with schizophrenia.

Corresponding Author: McCarroll, Steven A.

Nature (2016), doi:10.1038/nature16549, Published online 27 January 2016

Association between sleeping difficulty and type 2 diabetes in women

pjgrier Diabetes, Hot Topics in Research

Association between sleeping difficulty and type 2 diabetes in women

Abstract

Aims/hypothesis

Sleeping difficulty has been associated with type 2 diabetes in some prior studies. Whether the observed associations are independent of health behaviours, other cardiovascular risk factors or other sleep disorders is unclear.

Methods

We analysed data from 133,353 women without diabetes, cardiovascular disease and cancer at baseline in the Nurses’ Health Study (NHS, 2000–2010) and the NHSII (2001–2011). Sleeping difficulty was assessed as having difficulty falling or staying asleep ‘all of the time’ or ‘most of the time’ at baseline (2000 in NHS and 2001 in NHSII).

Results

We documented 6,407 incident cases of type 2 diabetes during up to 10 years of follow-up. After adjustment for lifestyle factors at baseline, comparing women with and without sleeping difficulty, the multivariate-adjusted HR (95% CI) for type 2 diabetes was 1.45 (95% CI 1.33, 1.58), which changed to 1.22 (95% CI 1.12, 1.34) after further adjustment for hypertension, depression and BMI based on the updated repeated measurements. Women who reported all four sleep conditions (sleeping difficulty, frequent snoring, sleep duration ≤6 h and sleep apnoea in NHS or rotating shift work in NHSII) had more than a fourfold increased likelihood of type 2 diabetes (HR 4.17, 95% CI 2.93, 5.91).

Conclusions/interpretation

Sleeping difficulty was significantly associated with type 2 diabetes. This association was partially explained by associations with hypertension, BMI and depression symptoms, and was particularly strong when combined with other sleep disorders. Our findings highlight the importance of sleep disturbance in the development and prevention of type 2 diabetes.

Yanping Li, Xiang Gao, John W. Winkelman, Elizabeth M. Cespedes, Chandra L. Jackson, Arthur S. Walters, Eva Schernhammer, Susan Redline, Frank B. Hu

Long-term toxic effects of proton radiotherapy for paediatric medulloblastoma: a phase 2 single-arm study

pjgrier Brain, Hot Topics in Research, Oncology, Pediatrics

Long-term toxic effects of proton radiotherapy for paediatric medulloblastoma: a phase 2 single-arm study

Background

Compared with traditional photon radiotherapy, proton radiotherapy irradiates less normal tissue and might improve health outcomes associated with photon radiotherapy by reducing toxic effects to normal tissue. We did a trial to assess late complications, acute side-effects, and survival associated with proton radiotherapy in children with medulloblastoma.

Methods

In this non-randomised, open-label, single-centre, phase 2 trial, we enrolled patients aged 3–21 years who had medulloblastoma. Patients had craniospinal irradiation of 18–36 Gy radiobiological equivalents (GyRBE) delivered at 1·8 GyRBE per fraction followed by a boost dose. The primary outcome was cumulative incidence of ototoxicity at 3 years, graded with the Pediatric Oncology Group ototoxicity scale (0–4), in the intention-to-treat population. Secondary outcomes were neuroendocrine toxic effects and neurocognitive toxic effects, assessed by intention-to-treat. This study is registered at ClinicalTrials.gov, number NCT00105560.

Findings

We enrolled 59 patients from May 20, 2003, to Dec 10, 2009: 39 with standard-risk disease, six with intermediate-risk disease, and 14 with high-risk disease. 59 patients received chemotherapy. Median follow-up of survivors was 7·0 years (IQR 5·2–8·6). All patients received the intended doses of proton radiotherapy. The median craniospinal irradiation dose was 23·4 GyRBE (IQR 23·4–27·0) and median boost dose was 54·0 GyRBE (IQR 54·0–54·0). Four (9%) of 45 evaluable patients had grade 3–4 ototoxicity according to Pediatric Oncology Group ototoxicity scale in both ears at follow-up, and three (7%) of 45 patients developed grade 3–4 ototoxicity in one ear, although one later reverted to grade 2. The cumulative incidence of grade 3–4 hearing loss at 3 years was 12% (95% CI 4–25). At 5 years, it was 16% (95% CI 6–29). Pediatric Oncology Group hearing ototoxicity score at a follow-up of 5·0 years (IQR 2·9–6·4) was the same as at baseline or improved by 1 point in 34 (35%) of 98 ears, worsened by 1 point in 21 (21%), worsened by 2 points in 35 (36%), worsened by 3 points in six (6%), and worsened by 4 points in two (2%). Full Scale Intelligence Quotient decreased by 1·5 points (95% CI 0·9–2·1) per year after median follow-up up of 5·2 years (IQR 2·6–6·4), driven by decrements in processing speed and verbal comprehension index. Perceptual reasoning index and working memory did not change significantly. Cumulative incidence of any neuroendocrine deficit at 5 years was 55% (95% CI 41–67), with growth hormone deficit being most common. We recorded no cardiac, pulmonary, or gastrointestinal late toxic effects. 3-year progression-free survival was 83% (95% CI 71–90) for all patients. In post-hoc analyses, 5-year progression-free survival was 80% (95% CI 67–88) and 5-year overall survival was 83% (95% CI 70–90).

Interpretation

Proton radiotherapy resulted in acceptable toxicity and had similar survival outcomes to those noted with conventional radiotherapy, suggesting that the use of the treatment may be an alternative to photon-based treatments.

Torunn I Yock, Beow Y Yeap, David H Ebb, Elizabeth Weyman, Bree R Eaton, Nicole A Sherry, Robin M Jones, Shannon M MacDonald, Margaret B Pulsifer, Beverly Lavally, Annah N Abrams, Mary S Huang, Karen J Marcus, Nancy J Tarbell

The Lancet Oncology

Prostate cancer discovery may make it easier to kill cancer cells

pjgrier January 5, 2016 Hot Topics in Research, Oncology, Prostate, Uncategorized

Checkpoint Kinase 2 Negatively Regulates Androgen Sensitivity and Prostate Cancer Cell Growth
Abstract:
Prostate cancer is the second leading cause of cancer death in American men, and curing metastatic disease remains a significant challenge. Nearly all patients with disseminated prostate cancer initially respond to androgen deprivation therapy (ADT), but virtually all patients will relapse and develop incurable castrationresistant prostate cancer (CRPC). A high-throughput RNAi screen to identify signaling pathways regulating prostate cancer cell growth led to our discovery that checkpoint kinase 2 (CHK2) knockdown dramatically increased prostate cancer growth and hypersensitized cells to low androgen levels. Mechanistic investigations revealed that the effects of CHK2 were dependent on the downstream signaling proteins CDC25C and CDK1. Moreover, CHK2depletion increased androgen receptor (AR) transcriptional activity on androgen-regulated genes, substantiating the finding that CHK2 affects prostate cancer proliferation, partly, through the AR. Remarkably, we further show that CHK2 is a novel ARrepressed gene, suggestive of a negative feedback loop between CHK2 and AR. In addition, we provide evidence that CHK2 physically associates with the AR and that cell-cycle inhibition increased this association. Finally, IHC analysis of CHK2 in prostate cancer patient samples demonstrated a decrease in CHK2 expression in high-grade tumors. In conclusion, we propose that CHK2 is a negative regulator of androgen sensitivity and prostate cancer growth, and that CHK2 signaling is lost during prostate cancer progression to castration resistance. Thus, perturbing CHK2 signaling may offer a new therapeutic approach for sensitizing CRPC to ADT and radiation.

Cancer Research. 12/1/2015, Vol. 75 Issue 23, p5093-5105. 13p.

Non-lethal Inhibition of Gut Microbial Trimethylamine Production for the Treatment of Atherosclerosis

pjgrier Cardiology, Hot Topics in Research, Uncategorized

Non-lethal Inhibition of Gut
Abstract:
Trimethylamine (TMA) N-oxide (TMAO), a gut-microbiota-dependent metabolite, both enhances atherosclerosis in animal models and is associated with cardiovascular risks in clinical studies. Here, we investigate the impact of targeted inhibition of the first step in TMAO generation, commensal microbial TMA production, on diet-induced atherosclerosis. A structural analog of choline, 3,3-dimethyl-1-butanol (DMB), is shown to non-lethally inhibit TMA formation from cultured microbes, to inhibit distinct microbial TMA lyases, and to both inhibit TMA production from physiologic polymicrobial cultures (e.g., intestinal contents, human feces) and reduce TMAO levels in mice fed a high-choline or L-carnitine diet. DMB inhibited choline diet-enhanced endogenous macrophage foam cell formation and atherosclerotic lesion development in apolipoprotein e^−/− mice without alterations in circulating cholesterol levels. The present studies suggest that targeting gut microbial production of TMA specifically and non-lethal microbial inhibitors in general may serve as a potential therapeutic approach for the treatment of cardiometabolic diseases. •Gut microbial trimethylamine lyases are a therapeutic target for atherosclerosis•3,3-dimethyl-1-butanol inhibits microbial trimethylamine formation•3,3-dimethyl-1-butanol attenuates choline diet-enhanced atherosclerosis•Non-lethal gut microbial enzyme inhibition can impact host cardiometabolic phenotypes Drugging the gut microbiota with a non-lethal inhibitor that blocks production of the metabolite trimethylamine reduces the formation of atherosclerotic lesions and represents the first step toward treatment of cardiometabolic diseases by targeting the microbiome.
Cell 17 December 2015 163(7):1585-1595

Practical experiences with eribulin in patients with metastatic breast cancer

pjgrier Breast, Hot Topics in Research, Oncology

Practical experiences with eribulin in patients with metastatic breast cancer
Background There is currently no standard therapy for women with metastatic or locally recurrent breast cancer. The microtubule polymerization inhibitor eribulin, approved in March 2011, is the first monochemotherapy with a proven survival benefit and tolerable toxicity in this patient group.
Patients and methods Using a retrospective analysis of 27 mostly heavily pretreated patients in two large German breast cancer centers, the efficacy and tolerability of eribulin in daily practice were compared with the results of the pivotal EMBRACE and 301 studies.
Results Despite the patients being older and having more advanced disease, the retrospective analysis showed a comparable progression-free survival of 3.7 months. When eribulin was used in an early-line treatment, the progression-free survival observed was 7 weeks longer compared with use in a late-line therapy. The differences in tolerability were not significant.

Anti-Cancer Drugs

Issue: Volume 27(2), February 2016, p 112–117

Management of Pulmonary Nodules by Community Pulmonologists

pjgrier Hot Topics in Research, Lung, Oncology

Management of Pulmonary Nodules by Community Pulmonologists
BACKGROUND: Pulmonary nodules (PNs) are a common reason for referral to pulmonologists. Th e majority of data for the evaluation and management of PNs is derived from studies performed in academic medical centers. Little is known about the prevalence and diagnosis of PNs, the use of diagnostic testing, or the management of PNs by community pulmonologists. METHODS: Th is multicenter observational record review evaluated 377 patients aged 40 to 89 years referred to 18 geographically diverse community pulmonary practices for intermediate PNs (8-20 mm). Study measures included the prevalence of malignancy, procedure/test use, and nodule pretest probability of malignancy as calculated by two previously validated models. Th e relationship between calculated pretest probability and management decisions was evaluated. RESULTS: Th e prevalence of malignancy was 25% (n 5 94). Nearly one-half of the patients (46%, n 5 175) had surveillance alone. Biopsy was performed on 125 patients (33.2%). A total of 77 patients (20.4%) underwent surgery, of whom 35% (n 5 27) had benign disease. PET scan was used in 141 patients (37%). Th e false-positive rate for PET scan was 39% (95% CI, 27.1%-52.1%). Pretest probability of malignancy calculations showed that 9.5% (n 5 36) were at a low risk, 79.6% (n 5 300) were at a moderate risk, and 10.8% (n 5 41) were at a high risk of malignancy. Th e rate of surgical resection was similar among the three groups (17%, 21%, 17%, respectively; P 5 .69). CONCLUSIONS: A substantial fraction of intermediate-sized nodules referred to pulmonologists ultimately prove to be lung cancer. Despite advances in imaging and nonsurgical biopsy techniques, invasive sampling of low-risk nodules and surgical resection of benign nodules remain common, suggesting a lack of adherence to guidelines for the management of PNs.
CHEST2015; 148(6): 1405 – 1414

Effects of aging on circadian patterns of gene expression in the human prefrontal cortex

pjgrier Brain, Dementia, Hot Topics in Research, Memory Impairment, Neurology

Effects of aging on circadian patterns of gene expression in the human prefrontal cortex
With aging, significant changes in circadian rhythms occur, including a shift in phase toward a “morning” chronotype and a loss of rhythmicity in circulating hormones. However, the effects of aging on molecular rhythms in the human brain have remained elusive. Here, we used a previously described time-of-death analysis to identify transcripts throughout the genome that have a significant circadian rhythm in expression in the human prefrontal cortex [Brodmann’s area 11 (BA11) and BA47]. Expression levels were determined by microarray analysis in 146 individuals. Rhythmicity in expression was found in ∼10% of detected transcripts (P < 0.05). Using a metaanalysis across the two brain areas, we identified a core set of 235 genes (q < 0.05) with significant circadian rhythms of expression. These 235 genes showed 92% concordance in the phase of expression between the two areas. In addition to the canonical core circadian genes, a number of other genes were found to exhibit rhythmic expression in the brain. Notably, we identified more than 1,000 genes (1,186 in BA11; 1,591 in BA47) that exhibited age-dependent rhythmicity or alterations in rhythmicity patterns with aging. Interestingly, a set of transcripts gained rhythmicity in older individuals, which may represent a compensatory mechanism due to a loss of canonical clock function. Thus, we confirm that rhythmic gene expression can be reliably measured in human brain and identified for the first time (to our knowledge) significant changes in molecular rhythms with aging that may contribute to altered cognition, sleep, and mood in later life.

Cho-Yi Chen, Proceedings of the National Academy of Sciences 2015 of the USA ; published ahead of print December 22, 2015, doi:10.1073/pnas.1508249112.