Glia instruct axon regeneration via a ternary modulation of neuronal calcium channels in Drosophila

A neuron's regenerative capacity is governed by its intrinsic and extrinsic environment. Both peripheral and central neurons exhibit cell-type-dependent axon regeneration, but the underlying mechanism is unclear. Glia provide a milieu essential for regeneration. However, the routes of glia-neuron signaling remain underexplored. Here, we show that regeneration specificity is determined by the axotomy-induced Ca2+ transients only in the fly regenerative neurons, which is mediated by L-type calcium channels, constituting the core intrinsic machinery. Peripheral glia regulate axon regeneration via a three-layered and balanced modulation. Glia-derived tumor necrosis factor acts through its neuronal receptor to maintain calcium channel expression after injury. Glia sustain calcium channel opening by enhancing membrane hyperpolarization via the inwardly-rectifying potassium channel (Irk1). Glia also release adenosine which signals through neuronal adenosine receptor (AdoR) to activate HCN channels (Ih) and dampen Ca2+ transients. Together, we identify a multifaceted glia-neuron coupling which can be hijacked to promote neural repair.

Pilot evaluation of a virtual training program for child injury prevention

Unintentional injuries are a leading cause of child death. The present study evaluated the effectiveness of a behavioral injury prevention program for children aged 3-18 years and their caregivers. To accommodate families during the Coronavirus-19 pandemic, training was modified to be delivered virtually. Forty-one children aged 3-18 years and 14 parents/caregivers of children aged 3-5 years attended one of several 4-hour online injury prevention training sessions directed toward residents of Washington state. Training was targeted to three different developmental stages (ages 3-5, 6-12 and 13-18 years). Study outcomes included knowledge about injury prevention strategies, perceived vulnerability for injury, self-efficacy to engage in safety behaviors and behavioral intentions to be safe. Following training, participants showed improved self-efficacy to stay safe, excellent knowledge about the learned material and increased behavioral intention to engage safely. There was minimal change in perceived vulnerability to injury among children; caregivers of young children felt their children were somewhat less vulnerable to injury following the training. Almost all participants said they would recommend the program to others. Results suggest that a virtual behavioral training program delivered remotely is feasible and may be effective to create behavior change and reduce child injury risk. Given its scalability and reach, such programs are recommended for further study, refinement and, if demonstrated effective in larger-scale controlled trials, dissemination to address the leading cause of child mortality in the United States, unintentional injury.

Mechanosensitive Ion Channels, Axonal Growth, and Regeneration

Cells sense and respond to mechanical stimuli by converting those stimuli into biological signals, a process known as mechanotransduction. Mechanotransduction is essential in diverse cellular functions, including tissue development, touch sensitivity, pain, and neuronal pathfinding. In the search for key players of mechanotransduction, several families of ion channels were identified as being mechanosensitive and were demonstrated to be activated directly by mechanical forces in both the membrane bilayer and the cytoskeleton. More recently, Piezo ion channels were discovered as a bona fide mechanosensitive ion channel, and its characterization led to a cascade of research that revealed the diverse functions of Piezo proteins and, in particular, their involvement in neuronal repair.

The Atr-Chek1 pathway inhibits axon regeneration in response to Piezo-dependent mechanosensation

Atr is a serine/threonine kinase, known to sense single-stranded DNA breaks and activate the DNA damage checkpoint by phosphorylating Chek1, which inhibits Cdc25, causing cell cycle arrest. This pathway has not been implicated in neuroregeneration. We show that in Drosophila sensory neurons removing Atr or Chek1, or overexpressing Cdc25 promotes regeneration, whereas Atr or Chek1 overexpression, or Cdc25 knockdown impedes regeneration. Inhibiting the Atr-associated checkpoint complex in neurons promotes regeneration and improves synapse/behavioral recovery after CNS injury. Independent of DNA damage, Atr responds to the mechanical stimulus elicited during regeneration, via the mechanosensitive ion channel Piezo and its downstream NO signaling. Sensory neuron-specific knockout of Atr in adult mice, or pharmacological inhibition of Atr-Chek1 in mammalian neurons in vitro and in flies in vivo enhances regeneration. Our findings reveal the Piezo-Atr-Chek1-Cdc25 axis as an evolutionarily conserved inhibitory mechanism for regeneration, and identify potential therapeutic targets for treating nervous system trauma.

A systematic review of the provision and efficacy of patient and carer information and support (PCIS) interventions for patients with dementia and their informal carers

BACKGROUND

The NHS dementia strategy identifies patient and carer information and support (PCIS) as a core component of gold-standard dementia care. This is the first systematic review of PCIS, performed to analyse the literature and evidence for these interventions.

AIMS

To systematically review literature evaluating the effectiveness of the provision of PCIS for people with dementia and their informal carers, in inpatient and outpatient settings.

METHODS

Searches of four online biomedical databases, accessed in September 2018. Studies were selected if they were: relating to people with dementia or their informal carers, based in inpatient or outpatient settings, published in English-language peer-reviewed journals no earlier than the year 2000 and assessed dementia-related information or social support interventions, by measuring qualitative or quantitative carer or patient-reported outcomes. Standardised data extraction and quality appraisal forms were used.

RESULTS

7 of 43 full-text papers analysed were eligible for analysis. 3 papers were different arms of one original study. Trends were present in the quantitative results towards reduced patient and carer depression and anxiety and the themes in the qualitative analysis were in favour of the intervention.

CONCLUSIONS

The studies analysed were too heterogeneous in design, population and outcomes measured to make a conclusive opinion about the efficacy of these interventions. It is surprising that for such a common condition, a gold-standard evidence-based intervention and standardised delivery for provision of PCIS for people living with dementia in the UK does not exist. Further research is therefore vital.

Cardiac biomarkers of disordered eating as a function of diagnostic subtypes

OBJECTIVE

The purpose of this study was to identify cardiac biomarkers of disordered eating as a function of diagnostic subtype as assessed via self-report inventory.

METHOD

Mean heart rate (HR), systolic and diastolic blood pressure, mean R wave amplitude (mV), mean T wave amplitude (mV), QTc interval (sec), Tpeak-Tend interval prolongation (sec), QTc interval prolongation (sec), QRS prolongation (sec), and spectral indicators of cardiac dysfunction (LF/HF spectral ratio, HF spectral power) were assessed via electrocardiography among women with no eating disorder symptoms (n = 32), subclinical eating disorder symptoms (n = 92), anorexia nervosa (n = 7), bulimia nervosa (n = 89), binge eating disorder (BED: n = 20), and other specified feeding and eating disorders (OSFED: n = 19).

RESULTS

MANOVA results showed statistically significant group differences. Follow-up tests revealed significantly decreased mean R wave amplitude among participants with self-indicated clinical (bulimia nervosa, binge eating disorder) and subclinical forms of disordered eating compared to asymptomatic controls.

DISCUSSION

Results suggest decreased mean R wave amplitude is a promising cardiac biomarker of disordered eating.

Mapping co-benefits for carbon storage and biodiversity to inform conservation policy and action

Integrated high-resolution maps of carbon stocks and biodiversity that identify areas of potential co-benefits for climate change mitigation and biodiversity conservation can help facilitate the implementation of global climate and biodiversity commitments at local levels. However, the multi-dimensional nature of biodiversity presents a major challenge for understanding, mapping and communicating where and how biodiversity benefits coincide with climate benefits. A new integrated approach to biodiversity is therefore needed. Here, we (a) present a new high-resolution map of global above- and below-ground carbon stored in biomass and soil, (b) quantify biodiversity values using two complementary indices (BIp and BIr) representing proactive and reactive approaches to conservation, and (c) examine patterns of carbon-biodiversity overlap by identifying 'hotspots' (20% highest values for both aspects). Our indices integrate local diversity and ecosystem intactness, as well as regional ecosystem intactness across the broader area supporting a similar natural assemblage of species to the location of interest. The western Amazon Basin, Central Africa and Southeast Asia capture the last strongholds of highest local biodiversity and ecosystem intactness worldwide, while the last refuges for unique biological communities whose habitats have been greatly reduced are mostly found in the tropical Andes and central Sundaland. There is 38 and 5% overlap in carbon and biodiversity hotspots, for proactive and reactive conservation, respectively. Alarmingly, only around 12 and 21% of these proactive and reactive hotspot areas, respectively, are formally protected. This highlights that a coupled approach is urgently needed to help achieve both climate and biodiversity global targets. This would involve (1) restoring and conserving unprotected, degraded ecosystems, particularly in the Neotropics and Indomalaya, and (2) retaining the remaining strongholds of intactness. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.

The Mechanosensitive Ion Channel Piezo Inhibits Axon Regeneration

Neurons exhibit a limited ability of repair. Given that mechanical forces affect neuronal outgrowth, it is important to investigate whether mechanosensitive ion channels may regulate axon regeneration. Here, we show that DmPiezo, a Ca²⁺-permeable non-selective cation channel, functions as an intrinsic inhibitor for axon regeneration in Drosophila. DmPiezo activation during axon regeneration induces local Ca²⁺ transients at the growth cone, leading to activation of nitric oxide synthase and the downstream cGMP kinase Foraging or PKG to restrict axon regrowth. Loss of DmPiezo enhances axon regeneration of sensory neurons in the peripheral and CNS. Conditional knockout of its mammalian homolog Piezo1 in vivo accelerates regeneration, while its pharmacological activation in vitro modestly reduces regeneration, suggesting the role of Piezo in inhibiting regeneration may be evolutionarily conserved. These findings provide a precedent for the involvement of mechanosensitive channels in axon regeneration and add a potential target for modulating nervous system repair.

A preliminary trial of an online dissonance-based eating disorder intervention

OBJECTIVE

We conducted a controlled randomized preliminary trial of an expanded online version of the Body Project (n = 46) compared to an assessment-only control condition (n = 36) via a longitudinal design (baseline, postintervention, 2-month follow-up) in a community sample of women (N = 82) with clinical (n = 53) and subclinical (n = 29) eating disorder symptoms.

METHOD

The traditional content of the Body Project was modified to include verbal, written, and behavioral exercises designed to dissuade objectification and maladaptive social comparison and adapted to an online format. Body dissatisfaction, self-esteem, self-objectification, thin-ideal internalization, maladaptive social comparison, trait anxiety, positive affect, negative affect, and eating disorder symptomatology were evaluated in the control and the online expanded Body Project condition at baseline, postintervention, and 2-month follow-up.

RESULTS

A 2 (condition: online expanded Body Project, control) × 3 (time: baseline, postintervention, 2-month follow-up) mixed factorial multivariate analysis of variance (MANOVA) was conducted to examine statistically significant group differences. As predicted, results indicated a statistically significant condition × time interaction.

CONCLUSIONS

Participants in the expanded online Body Project condition showed significant reductions in eating disorder symptoms and several associated psychological risk correlates from baseline to postintervention and follow-up; contrary to predictions, eating disorder symptoms and risk correlates were not significantly lower in the online expanded Body Project condition compared to the waitlist control condition at postintervention or 2-month follow-up.

Secukinumab significantly reduces psoriasis-related work impairment and indirect costs compared with ustekinumab and etanercept in the United Kingdom

Background

Psoriasis causes work productivity impairment that increases with disease severity. Whether differential treatment efficacy translates into differential indirect cost savings is unknown.

Objective

To assess work hours lost and indirect costs associated with secukinumab versus ustekinumab and etanercept in the United Kingdom (UK).

Methods

This was a post hoc analysis of work impairment data collected in the CLEAR study (secukinumab vs. ustekinumab) and applied to the FIXTURE study (secukinumab vs. etanercept). Weighted weekly and annual average indirect costs per patient per treatment were calculated from (i) overall work impairment derived from Work Productivity and Activity Impairment data collected in CLEAR at 16 and 52 weeks by Psoriasis Area and Severity Index (PASI) response level; (ii) weekly/annual work productivity loss by PASI response level; (iii) weekly and annual indirect costs by PASI response level, based on hours of work productivity loss; and (iv) weighted average indirect costs for each treatment. In the primary analysis, work impairment data for employed patients in CLEAR at Week 16 were used to compare secukinumab and ustekinumab. Secondary analyses were conducted at different time points and with patient cohorts, including FIXTURE.

Results

In CLEAR, 452 patients (67%) were employed at baseline. At Week 16, percentages of weekly work impairment/mean hours lost decreased with higher PASI: PASI < 50: 22.8%/7.60 h; PASI 50–74: 13.3%/4.45 h; PASI 75–89: 6.4%/2.14 h; PASI ≥ 90: 4.9%/1.65 h. Weighted mean weekly/annual work hours lost were significantly lower for secukinumab than ustekinumab (1.96/102.51 vs. 2.40/125.12; P = 0.0006). Results were consistent for secukinumab versus etanercept (2.29/119.67 vs. 3.59/187.17; Ρ<0.0001). Average annual indirect cost savings with secukinumab were £355 vs. ustekinumab and £1061 versus etanercept. Results at 52 weeks were similar.

Conclusions

Secukinumab significantly reduced work impairment and associated indirect costs of psoriasis compared with ustekinumab and etanercept at Week 16 through 52 in the United Kingdom.

Evaluating the effectiveness of a home-based exercise programme delivered through a tablet computer for preventing falls in older community-dwelling people over 2 years: study protocol for the Standing Tall randomised controlled trial

INTRODUCTION

In order to prevent falls, older people should exercise for at least 2 h per week for 6 months, with a strong focus on balance exercises. This article describes the design of a randomised controlled trial to evaluate the effectiveness of a home-based exercise programme delivered through a tablet computer to prevent falls in older people.

METHODS AND ANALYSIS

Participants aged 70 years or older, living in the community in Sydney will be recruited and randomly allocated to an intervention or control group. The intervention consists of a tailored, home-based balance training delivered through a tablet computer. Intervention participants will be asked to complete 2 h of exercises per week for 2 years. Both groups will receive an education programme focused on health-related information relevant to older adults, delivered through the tablet computer via weekly fact sheets. Primary outcome measures include number of fallers and falls rate recorded in weekly fall diaries at 12 months. A sample size of 500 will be necessary to see an effect on falls rate. Secondary outcome measures include concern about falling, depressive symptoms, health-related quality of life and physical activity levels (in all 500 participants); and physiological fall risk, balance, functional mobility, gait, stepping and cognitive performance (in a subsample of 200 participants). Adherence, acceptability, usability and enjoyment will be recorded in intervention group participants over 2 years. Data will be analysed using the intention-to-treat principle. Secondary analyses are planned in people with greater adherence. Economic analyses will be assessed from a health and community care provider perspective.

ETHICS AND DISSEMINATION

Ethical approval was obtained from UNSW Ethics Committee in December 2014 (ref number HC#14/266). Outcomes will be disseminated through publication in peer-reviewed journals and presentations at international conferences.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN)12615000138583.

Clinical isolates of Candida albicans, Candida tropicalis, and Candida krusei have different susceptibilities to Co(II) and Cu(II) complexes of 1,10-phenanthroline

The minimal inhibitory concentrations (MICs) of copper and cobalt based dimeric pyrophosphate complexes with capping 1,10-phenanthroline groups on clinical isolates of C. albicans (28 isolates), C. krusei (20 isolates) and C. tropicalis (20 isolates) are reported. C. albicans was inhibited by the cobalt complex better than by the copper complex, while C. krusei demonstrated the opposite results. C. tropicalis showed similar sensitivities to both metals in terms of calculated MIC50 values but was more sensitive to cobalt when MIC90 values were noted. Knockout strains of C. albicans that had the copper efflux protein P-type ATPase (CRP1), the copper binding metallothionein CUP1 or both CRP1/CUP1 removed clearly demonstrate that the origins of copper resistant in C. albicans lies primarily in the P-type ATPase, with the MT playing an important secondary role in the absence of the efflux protein. This study suggests that certain strains of Candida have evolved to protect against particular metal ions and that in the case of C. albicans, a primary invasive fungal species, cobalt may be a good starting-point for new therapeutic development.

Non-Gaussian diffusion MRI of gray matter is associated with cognitive impairment in multiple sclerosis

BACKGROUND

Non-Gaussian diffusion imaging by using diffusional kurtosis imaging (DKI) allows assessment of isotropic tissue as of gray matter (GM), an important limitation of diffusion tensor imaging (DTI).

OBJECTIVE

In this study, we describe DKI and DTI metrics of GM in multiple sclerosis (MS) patients and their association with cognitive deficits.

METHODS

Thirty-four patients with relapsing-remitting MS and 17 controls underwent MRI on a 3T scanner including a sequence for DKI with 30 diffusion directions and 3b values for each direction. Mean kurtosis (MK), mean diffusivity and fractional anisotropy (FA) of cortical and subcortical GM were measured using histogram analysis. Spearman rank correlations were used to characterize associations among imaging measures and clinical/neuropsychological scores.

RESULTS

In cortical GM, a significant decrease of MK (0.68 vs. 0.73; p < 0.001) and increase of FA (0.16 vs. 0.13; p < 0.001) was found in patients compared to controls. Decreased cortical MK was correlated with poor performance on the Delis-Kaplan Executive Function System test (r = 0.66, p = 0.01).

CONCLUSION

Mean kurtosis is sensitive to abnormality in GM of MS patients and can provide information that is complementary to that of conventional DTI-derived metrics. The association between MK and cognitive deficits suggests that DKI might serve as a clinically relevant biomarker for cortical injury.

Brain iron quantification in mild traumatic brain injury: a magnetic field correlation study

BACKGROUND AND PURPOSE

Experimental studies have suggested a role for iron accumulation in the pathology of TBI. Magnetic field correlation MR imaging is sensitive to the presence of non-heme iron. The aims of this study are to 1) assess the presence, if any, and the extent of iron deposition in the deep gray matter and regional white matter of patients with mTBI by using MFC MR imaging; and 2) investigate the association of regional brain iron deposition with cognitive and behavioral performance of patients with mTBI.

MATERIALS AND METHODS

We prospectively enrolled 28 patients with mTBI. Eighteen healthy subjects served as controls. The subjects were administered the Stroop color word test, the Verbal Fluency Task, and the Post-Concussion Symptoms Scale. The MR imaging protocol (on a 3T imager) consisted of conventional brain imaging and MFC sequences. After the calculation of parametric maps, MFC was measured by using a region of interest approach. MFC values across groups were compared by using analysis of covariance, and the relationship of MFC values and neuropsychological tests were evaluated by using Spearman correlations.

RESULTS

Compared with controls, patients with mTBI demonstrated significant higher MFC values in the globus pallidus (P = .002) and in the thalamus (P = .036). In patients with mTBI, Stroop test scores were associated with the MFC value in frontal white matter (r = -0.38, P = .043).

CONCLUSIONS

MFC values were significantly elevated in the thalamus and globus pallidus of patients with mTBI, suggesting increased accumulation of iron. This supports the hypothesis that deep gray matter is a site of injury in mTBI and suggests a possible role for iron accumulation in the pathophysiological events after mTBI.

Multimodality imaging in the surgical treatment of children with nonlesional epilepsy

OBJECTIVES

To evaluate the diagnostic value of individual noninvasive presurgical modalities and to study their role in surgical management of nonlesional pediatric epilepsy patients.

METHODS

We retrospectively studied 14 children (3-18 years) with nonlesional intractable focal epilepsy. Clinical characteristics, surgical outcome, localizing features on 3 presurgical diagnostic tests (subtraction peri-ictal SPECT coregistered to MRI [SISCOM], statistical parametric mapping [SPM] analysis of [18F] FDG-PET, magnetoencephalography [MEG]), and intracranial EEG (iEEG) were reviewed. The localization of each individual test was determined for lobar location by visual inspection. Concordance of localization between each test and iEEG was scored as follows: 2=lobar concordance; 1=hemispheric concordance; 0=discordance or nonlocalization. Total concordance score in each patient was measured by the summation of concordance scores for all 3 tests.

RESULTS

Seven (50%) of 14 patients were seizure-free for at least 12 months after surgery. One (7%) had only rare seizures and 6 (43%) had persistent seizures. MEG (79%, 11/14) and SISCOM (79%, 11/14) showed greater lobar concordance with iEEG than SPM-PET (13%, 3/14) (p<0.05). SPM-PET provided hemispheric lateralization (71%, 10/14) more often than lobar localization. Total concordance score tended to be greater for seizure-free patients (4.7) than for non-seizure-free patients (3.9).

CONCLUSIONS

Our data suggest that MEG and SISCOM are better tools for lobar localization than SPM analysis of FDG-PET in children with nonlesional epilepsy. A multimodality approach may improve surgical outcome as well as selection of surgical candidates in patients without MRI abnormalities.

Neurolinguistic programming used to reduce the need for anaesthesia in claustrophobic patients undergoing MRI

The purpose of this study was to assess the success of neurolinguistic programming in reducing the need for general anaesthesia in claustrophobic patients who require MRI and to consider the financial implications for health providers. This was a prospective study performed in 2006 and 2007 at a teaching hospital in England and comprised 50 adults who had unsuccessful MR examinations because of claustrophobia. The main outcome measures were the ability to tolerate a successful MR examination after neurolinguistic programming, the reduction of median anxiety scores produced by neurolinguistic programming, and models of costs for various imaging pathways. Neurolinguistic programming allowed 38/50 people (76%) to complete the MR examination successfully. Overall, the median anxiety score was significantly reduced following the session of neurolinguistic programming. In conclusion, neurolinguistic programming reduced anxiety and subsequently allowed MRI to be performed without resorting to general anaesthesia in a high proportion of claustrophobic adults. If these results are reproducible, there will be major advantages in terms of patient safety and costs.

Quantitative assessment of iron accumulation in the deep gray matter of multiple sclerosis by magnetic field correlation imaging

BACKGROUND AND PURPOSE

Deposition of iron has been recognized recently as an important factor of pathophysiologic change including neurodegenerative processes in multiple sclerosis (MS). We propose that there is an excess accumulation of iron in the deep gray matter in patients with MS that can be measured with a newly developed quantitative MR technique--magnetic field correlation (MFC) imaging.

MATERIALS AND METHODS

With a 3T MR system, we studied 17 patients with relapsing-remitting MS and 14 age-matched healthy control subjects. We acquired MFC imaging using an asymmetric single-shot echo-planar imaging sequence. Regions of interest were selected in both deep gray matter and white matter regions, and the mean MFC values were compared between patients and controls. We also correlated the MFC data with lesion load and neuropsychologic tests in the patients.

RESULTS

MFC measured in the deep gray matter in patients with MS was significantly higher than that in the healthy controls (P < or = .03), with an average increase of 24% in the globus pallidus, 39.5% in the putamen, and 30.6% in the thalamus. The increased iron deposition measured with MFC in the deep gray matter in the patients correlated positively with the total number of MS lesions (thalamus: r = 0.61, P = .01; globus pallidus: r = 0.52, P = .02). A moderate but significant correlation between the MFC value in the deep gray matter and the neuropsychologic tests was also found.

CONCLUSION

Quantitative measurements of iron content with MFC demonstrate increased accumulation of iron in the deep gray matter in patients with MS, which may be associated with the disrupted iron outflow pathway by lesions. Such abnormal accumulation of iron may contribute to neuropsychologic impairment and have implications for neurodegenerative processes in MS.

Predictability of the clinical course of juvenile dermatomyositis based on initial muscle biopsy: A retrospective study of 72 patients

OBJECTIVE

Except when the diagnosis of juvenile dermatomyositis (DM) is in doubt, a case has not been made for routine muscle biopsy (MB). We sought to determine whether MB findings prior to systemic therapy have prognostic value.

METHODS

We reviewed the hospital records and slides prepared from the initial open MB of 72 patients treated at one center between 1977 and 2002 and followed for a minimum of 2 years. None of the patients had received a course of systemic corticosteroid therapy at the time of MB. Our approach to MB evaluation was based on recent discussions with muscle pathology experts to develop criteria for assessing inflammation, vasculopathy, myofiber atrophy, regeneration, acute and chronic myopathic change, and stromal changes. Using simple and multivariate logistic regression, we tested each MB parameter for ability to predict outcome using 2 published classification systems.

RESULTS

Extensive active myopathic changes (excluding regeneration) and central nuclei without basophilia predicted chronic juvenile DM. Severe arteropathic change, positive arterial direct immunofluorescence, obvious foci of severe capillary loss/endomysial fibrosis, and muscle infarcts predicted chronic juvenile DM, particularly with ulceration. Other MB parameters, regardless of severity, were not significant predictors of chronic juvenile DM versus limited disease.

CONCLUSION

A scoring system for evaluating pretreatment MB in juvenile DM that focuses on extent of necrotizing myopathy, severity of vasculopathy, and features of established chronicity such as central nucleation of nonbasophilic myofibers may provide a basis for stratification of therapeutic regimens according to risk for chronic disease. The validity of our findings should be prospectively tested.

Hepatocyte glycogen accumulation in patients undergoing dietary management of urea cycle defects mimics storage disease

OBJECTIVES

Anecdotal reports have described excess hepatocyte glycogen in patients with urea cycle enzyme defects. Retrospectively, the authors evaluated the prevalence and possible cause of liver glycogen accumulation in such patients.

METHODS

The authors searched the files of the Division of Pathology at Cincinnati Children's Hospital from 1975 and 2004 for cases of urea cycle enzyme defects and identified 11 patients who had had liver biopsy performed and/or liver transplantation. All patients were on diets containing essential amino acids as the protein source before liver biopsy and/or transplantation.

RESULTS

All but one patient had focal or diffuse glycogen accumulation in hepatocytes in at least one specimen by light microscopic examination. Two young infants also had cholestasis. Electron microscopy performed on six patients showed diffuse or focal glycogen excess in the cytoplasm of individual hepatocytes. Biochemical studies of three patients revealed two with hepatic glycogen content in the upper normal range and one that was abnormally high. Glycolytic enzyme activities were normal in two patients, and one patient had low phosphorylase activity.

CONCLUSIONS

Hepatocyte glycogen accumulation in urea cycle enzyme defects resembles that seen in glycogen storage disease but can be distinguished in most cases by non-uniformity of distribution and/or the absence of sinusoidal compression by expanded hepatocytes. We speculate that therapeutic modification of dietary protein content by restriction to essential amino acids, including leucine, may promote glycogen accumulation by increasing insulin secretion.

Plasminogen regulates pro-opiomelanocortin processing

BACKGROUND

Plasminogen-deficient mice exhibit behavioral differences in response to stress, including a markedly reduced acoustic startle reflex response compared with wild-type (WT) littermates. The acoustic startle reflex activates the hypothalamic-pituitary axis and is modulated by these hormones.

OBJECTIVES

The purpose of this study was to investigate whether plasminogen plays a role in the processing of hormones in the hypothalamic-pituitary axis.

METHODS

In this study the concentration of plasma, pituitary, and brain hypothalamic-pituitary axis hormones and precursor processing was examined in WT and plasminogen deficient (Plg-/-) mice before and after acoustic startle reflex testing.

RESULTS

Plasma adrenocorticotropic hormone (ACTH), beta-endorphin and alpha-melanocyte stimulating hormone were elevated after acoustic startle reflex testing in both WT and (Plg-/-) mice. However, in the Plg-/- mice, beta-endorphin values were 43, 35, and 45% lower in the plasma, pituitary, and whole brain, respectively, compared with the WT mice. Plasmin readily degraded precursor peptides, the 23-kDa precursor, beta-lipotropin, and ACTH, when presented as purified proteins or as the secretory products of mouse pituitary cells (AtT-20). The precursor peptide, 23 kDa, for beta-endorphin and alpha-melanocyte stimulating hormone was reduced in the pituitaries from the Plg-/- mice, and the mRNA for Plg was found in pituitaries from WT mice. Infusion of beta-endorphin and alpha-melanocyte stimulating hormone into the brain of Plg-/- mice increased acoustic startle reflex.

CONCLUSIONS

The results of this study show that plasmin is involved in the processing of hormones derived from the pro-opiomelanocortin precursor in the intermediate pituitary. A deficiency of plasminogen reduces processing of beta-endorphin and alpha-melanocyte stimulating hormone, and interferes with normal brain function.