PIK3R1 Mutations Cause Syndromic Insulin Resistance with Lipoatrophy

Short stature, hyperextensibility of joints and/or inguinal hernia, ocular depression, Rieger anomaly, and teething delay (SHORT) syndrome is a developmental disorder with an unknown genetic cause and hallmarks that include insulin resistance and lack of subcutaneous fat. We ascertained two unrelated individuals with SHORT syndrome, hypothesized that the observed phenotype was most likely due to de novo mutations in the same gene, and performed whole-exome sequencing in the two probands and their unaffected parents. We then confirmed our initial observations in four other subjects with SHORT syndrome from three families, as well as 14 unrelated subjects presenting with syndromic insulin resistance and/or generalized lipoatrophy associated with dysmorphic features and growth retardation. Overall, we identified in nine affected individuals from eight families de novo or inherited PIK3R1 mutations, including a mutational hotspot (c.1945C>T [p.Arg649Trp]) present in four families. PIK3R1 encodes the p85α, p55α, and p50α regulatory subunits of class IA phosphatidylinositol 3 kinases (PI3Ks), which are known to play a key role in insulin signaling. Functional data from fibroblasts derived from individuals with PIK3R1 mutations showed severe insulin resistance for both proximal and distal PI3K-dependent signaling. Our findings extend the genetic causes of severe insulin-resistance syndromes and provide important information with respect to the function of PIK3R1 in normal development and its role in human diseases, including growth delay, Rieger anomaly and other ocular affections, insulin resistance, diabetes, paucity of fat, and ovarian cysts.     

Genomic Pathology of SLE-Associated Copy-Number Variation at the FCGR2C/FCGR3B/FCGR2B Locus

Reduced FCGR3B copy number is associated with increased risk of systemic lupus erythematosus (SLE). The five FCGR2/FCGR3 genes are arranged across two highly paralogous genomic segments on chromosome 1q23. Previous studies have suggested mechanisms for structural rearrangements at the FCGR2/FCGR3 locus and have proposed mechanisms whereby altered FCGR3B copy number predisposes to autoimmunity, but the high degree of sequence similarity between paralogous segments has prevented precise definition of the molecular events and their functional consequences. To pursue the genomic pathology associated with FCGR3B copy-number variation, we integrated sequencing data from fosmid and bacterial artificial chromosome clones and sequence-captured DNA from FCGR3B-deleted genomes to establish a detailed map of allelic and paralogous sequence variation across the FCGR2/FCGR3 locus. This analysis identified two highly paralogous 24.5 kb blocks within the FCGR2C/FCGR3B/FCGR2B locus that are devoid of nonpolymorphic paralogous sequence variations and that define the limits of the genomic regions in which nonallelic homologous recombination leads to FCGR2C/FCGR3B copy-number variation. Further, the data showed evidence of swapping of haplotype blocks between these highly paralogous blocks that most likely arose from sequential ancestral recombination events across the region. Functionally, we found by flow cytometry, immunoblotting and cDNA sequencing that individuals with FCGR3B-deleted alleles show ectopic presence of FcγRIIb on natural killer (NK) cells. We conclude that FCGR3B deletion juxtaposes the 5′-regulatory sequences of FCGR2C with the coding sequence of FCGR2B, creating a chimeric gene that results in an ectopic accumulation of FcγRIIb on NK cells and provides an explanation for SLE risk associated with reduced FCGR3B gene copy number.     

Synthesis of new N-(arylcyclopropyl)acetamides and N-(arylvinyl)acetamides as conformationally-restricted ligands for melatonin receptors

N-(Arylcyclopropyl)acetamides and N-(arylvinyl)acetamides or methyl ureas have been prepared as constrained analogues of melatonin. The affinity of these new compounds for chicken brain melatonin receptors and recombinant human MT₁ and MT₂ receptors was evaluated using 2-[¹²⁵I]-iodomelatonin as radioligand. Strict ethylenic or cyclopropyl analogues of the commercialized agonist agomelatine (Valdoxan®) were equipotent to agomelatine in binding bioassays. However, the ethylenic analogue was more effective than the cyclopropyl one in the melanophore aggregation bioassay, but was still less potent than the disubstituted 2,7-dimethoxy-naphtalenic compounds.     

The effects of Eculizumab on the pathology of malignant atrophic papulosis

Background

Degos disease is a frequently fatal and incurable occlusive vasculopathy most commonly affecting the skin, gastrointestinal tract and brain. Vascular C5b-9 deposition and a type I interferon (IFN) rich microenvironment are held to be pathogenetically important in the evolution of the vascular changes. We recently discovered the use of eculizumab as a salvage drug in the treatment of near fatal Malignant atrophic papulosis (MAP). The effects of eculizumab on the pathology of MAP are explored.

Methods

Archival skin and gastrointestinal biopsy material was procured over a 2.5-year period before and after eculizumab therapy in our index case. Routine light microscopy and immunohistochemical assessment for C3d, C4d, C5b-9, MxA and caspase 3 were examined. Direct immunofluorescent studies were also conducted on select biopsy material.

Results

The patient had received eculizumab as a emergent life saving measure and following rapid improvement he continued with biweekly infusions for 4 years. Although improved he continues to have signs and symptoms of persistent abdominal disease. Pre-Eculizumab biopsies showed an active thrombotic microangiopathy associated with a high type I interferon signature and extensive vascular deposits of C5b-9 in skin and gastrointestinal biopsies. Endothelial cell apoptosis as revealed by Caspase 3 expression was noted. Inflammation comprising lymphocytes and macrophages along with mesenchymal mucin was observed as well. Post-eculizumab biopsies did not show active luminal thrombosis but only chronic sequelae of prior episodes of vascular injury. There was no discernible caspase 3 expression. After 12 months of therapy, C5b-9 was no longer detectable in tissue. The high type I IFN signature and inflammation along with mucin deposition was not altered by the drug. In addition, there was little effect of the drug on the occlusive fibrointimal arteriopathy which appears to be one characterized by extensive myofibroblastic expansion of the intima potentially as revealed by staining for smooth muscle actin without immunoreactivity for desmin and myogenin.

Conclusions

Complement activation and enhanced endothelial cell apoptosis play an important role in the thrombotic complications of MAP. However, the larger vessel proliferative intimal changes appear to be independent of complement activation and may be on the basis of other upstream mechanisms. Monitoring C5b-9 deposition in tissue is likely not of great value in assessing treatment response to eculizumab given the persistence of C5b-9 in tissue for several months despite clinically effective C5 blocking therapy. A more integrated approach addressing upstream and downstream pathways in addition to those attributable to complement activation are critical for the successful treatment of MAP. Eculizumab may be used as salvage therapy in critically ill patients with thrombotic microangiopathy.

     

Younger and older chronic somatoform pain patients in psycho-diagnostics,physician-patient relationship and treatment outcome

Introduction

Patients with chronic pain are found with highly variable clinical presentation and differing physical complaints. They are seen as a heterogenic group. Based on clinical observations, elderly patients seem to differ from younger patients with chronic pain. We examined whether there were systematic differences between young and old pain patients.

Methods

As part of a routine evaluation of university hospital care, a newly developed psychosomatic treatment model for chronic somatoform pain disorders was examined. The basis for treatment efficacy was a target-oriented, specific somatic and psychological intervention that included a stable physician-patient relationship. Particular attention was paid to differences in treatment outcome with regard to changes in both physical and psychopathological symptom levels. We hypothesised that younger pain patients had higher psychological burden and benefitted more from our treatment than older pain patients.

Results

Overall, 179 inpatients (57.5% women) with chronic pain were examined (age between 16 and 79 years). The group as a whole yielded high scores on the somatisation dimension (SCL-90) and showed a considerable amount of psychopathological symptoms, such as depressive mood and anxiety (HADS) and a great emotional instability (FPI-R). Age differences were only found with regards to patients’ degree of aggression (SCl-90): younger patients showed higher aggressive tendencies than older ones (p< 0.05). The treatment offered helped patients in both age groups especially with regard to reduction of depressive mood (HADS, p< 0.01) and anxiety levels (HADS, p< 0.01). Regression analysis showed different age groups and gender as significant predictors of anxiety reduction under therapy (R²=.108; model: p< 0.01).

Discussion and conclusion

Results show that younger chronic pain patients suffer more from a considerable amount of psychological distress than older ones, but our treatment approach was equally effective in both groups. However, age and gender differences, as well as the patient’s baseline level of anxiety influenced the outcome. These factors need to be studied in future research.

     

An Analysis of Pregnancy-Related Mortality in the KEMRI/CDC Health and Demographic Surveillance System in Western Kenya

Background

Pregnancy-related (PR) deaths are often a result of direct obstetric complications occurring at childbirth.

Methods and Findings

To estimate the burden of and characterize risk factors for PR mortality, we evaluated deaths that occurred between 2003 and 2008 among women of childbearing age (15 to 49 years) using Health and Demographic Surveillance System data in rural western Kenya. WHO ICD definition of PR mortality was used: “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death”. In addition, symptoms and events at the time of death were examined using the WHO verbal autopsy methodology. Deaths were categorized as either (i) directly PR: main cause of death was ascribed as obstetric, or (ii) indirectly PR: main cause of death was non-obstetric. Of 3,223 deaths in women 15 to 49 years, 249 (7.7%) were PR. One-third (34%) of these were due to direct obstetric causes, predominantly postpartum hemorrhage, abortion complications and puerperal sepsis. Two-thirds were indirect; three-quarters were attributable to human immunodeficiency virus (HIV/AIDS), malaria and tuberculosis. Significantly more women who died in lower socio-economic groups sought care from traditional birth attendants (p = 0.034), while less impoverished women were more likely to seek hospital care (p = 0.001). The PR mortality ratio over the six years was 740 (95% CI 651–838) per 100,000 live births, with no evidence of reduction over time (χ² linear trend = 1.07; p = 0.3).

Conclusions

These data supplement current scanty information on the relationship between infectious diseases and poor maternal outcomes in Africa. They indicate low uptake of maternal health interventions in women dying during pregnancy and postpartum, suggesting improved access to and increased uptake of skilled obstetric care, as well as preventive measures against HIV/AIDS, malaria and tuberculosis among all women of childbearing age may help to reduce pregnancy-related mortality.     

TGF-b Superfamily Cytokine MIC-1/GDF15 Is a Physiological Appetite and Body Weight Regulator

The TGF-b superfamily cytokine MIC-1/GDF15 circulates in all humans and when overproduced in cancer leads to anorexia/cachexia, by direct action on brain feeding centres. In these studies we have examined the role of physiologically relevant levels of MIC-1/GDF15 in the regulation of appetite, body weight and basal metabolic rate. MIC-1/GDF15 gene knockout mice (MIC-1^−/−) weighed more and had increased adiposity, which was associated with increased spontaneous food intake. Female MIC-1^−/− mice exhibited some additional alterations in reduced basal energy expenditure and physical activity, possibly owing to the associated decrease in total lean mass. Further, infusion of human recombinant MIC-1/GDF15 sufficient to raise serum levels in MIC-1^−/− mice to within the normal human range reduced body weight and food intake. Taken together, our findings suggest that MIC-1/GDF15 is involved in the physiological regulation of appetite and energy storage.     

Hereditary Angioedema Attacks Resolve Faster and Are Shorter after Early Icatibant Treatment

Background

Attacks of hereditary angioedema (HAE) are unpredictable and, if affecting the upper airway, can be lethal. Icatibant is used for physician- or patient self-administered symptomatic treatment of HAE attacks in adults. Its mode of action includes disruption of the bradykinin pathway via blockade of the bradykinin B₂ receptor. Early treatment is believed to shorten attack duration and prevent severe outcomes; however, evidence to support these benefits is lacking.

Objective

To examine the impact of timing of icatibant administration on the duration and resolution of HAE type I and II attacks.

Methods

The Icatibant Outcome Survey is an international, prospective, observational study for patients treated with icatibant. Data on timings and outcomes of icatibant treatment for HAE attacks were collected between July 2009–February 2012. A mixed-model of repeated measures was performed for 426 attacks in 136 HAE type I and II patients.

Results

Attack duration was significantly shorter in patients treated <1 hour of attack onset compared with those treated ≥1 hour (6.1 hours versus 16.8 hours [p<0.001]). Similar significant effects were observed for <2 hours versus ≥2 hours (7.2 hours versus 20.2 hours [p<0.001]) and <5 hours versus ≥5 hours (8.0 hours versus 23.5 hours [p<0.001]). Treatment within 1 hour of attack onset also significantly reduced time to attack resolution (5.8 hours versus 8.8 hours [p<0.05]). Self-administrators were more likely to treat early and experience shorter attacks than those treated by a healthcare professional.

Conclusion

Early blockade of the bradykinin B₂ receptor with icatibant, particularly within the first hour of attack onset, significantly reduced attack duration and time to attack resolution.     

A Conserved Aspartic Acid Is Important for Agonist (VUAA1) and Odorant/Tuning Receptor-Dependent Activation of the Insect Odorant Co-Receptor (Orco)

Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco). An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca²⁺ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ∼2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.