Genome-wide analysis identified novel susceptible genes of restless legs syndrome in migraineurs

Background

Restless legs syndrome is a highly prevalent comorbidity of migraine; however, its genetic contributions remain unclear.

Objectives

To identify the genetic variants of restless legs syndrome in migraineurs and to investigate their potential pathogenic roles.

Methods

We conducted a two-stage genome-wide association study (GWAS) to identify susceptible genes for restless legs syndrome in 1,647 patients with migraine, including 264 with and 1,383 without restless legs syndrome, and also validated the association of lead variants in normal controls unaffected with restless legs syndrome (n = 1,053). We used morpholino translational knockdown (morphants), CRISPR/dCas9 transcriptional knockdown, transient CRISPR/Cas9 knockout (crispants) and gene rescue in one-cell stage embryos of zebrafish to study the function of the identified genes.

Results

We identified two novel susceptibility loci rs6021854 (in VSTM2L) and rs79823654 (in CCDC141) to be associated with restless legs syndrome in migraineurs, which remained significant when compared to normal controls. Two different morpholinos targeting vstm2l and ccdc141 in zebrafish demonstrated behavioural and cytochemical phenotypes relevant to restless legs syndrome, including hyperkinetic movements of pectoral fins and decreased number in dopaminergic amacrine cells. These phenotypes could be partially reversed with gene rescue, suggesting the specificity of translational knockdown. Transcriptional CRISPR/dCas9 knockdown and transient CRISPR/Cas9 knockout of vstm2l and ccdc141 replicated the findings observed in translationally knocked-down morphants.

Conclusions

Our GWAS and functional analysis suggest VSTM2L and CCDC141 are highly relevant to the pathogenesis of restless legs syndrome in migraineurs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01409-9.

Contralateral exploration and repair of occult inguinal hernias during laparoscopic inguinal hernia repair: systematic review and Markov decision process

BACKGROUND

Contralateral clinically occult hernias are frequently noted at the time of laparoscopic unilateral inguinal hernia repair. There is no consensus on the role of contralateral exploration and repair. This systematic review assessed the safety and efficacy of operative repair of occult contralateral inguinal hernias found during unilateral repair.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception to February 2020. Adults diagnosed with a unilateral inguinal hernia undergoing laparoscopic repair were included. The primary outcome was the incidence of occult contralateral hernias. Summative outcomes of operative and expectant management were reported along with development of a Markov decision process.

RESULTS

Thirteen studies (1 randomized trial, 12 observational cohorts) with 5000 patients were included. The incidence of occult contralateral inguinal hernias was 14.6 (range 7.3-50.1) per cent. Among patients who underwent repair, 10.5 (4.3-17.0) per cent experienced a postoperative complication. Of patients managed expectantly, 29 per cent later required elective repair for symptoms. Mean follow-up was 36 (range 2-218) months. Using a Markov decision process, it was calculated that, for every 1000 patients undergoing unilateral inguinal hernia repair, contralateral exploration would identify 150 patients with an occult hernia. Repair would result in 15 patients developing a postoperative complication and 105 undergoing unnecessary repair. Alternatively, expectant management would result in 45 patients requiring subsequent repair.

CONCLUSION

Contralateral repair is not warranted in patients with occult hernias diagnosed at the time of elective hernia repair. The evidence is largely based on observational studies at high risk of bias.

Zinc oxide nanoparticles modulate the gene expression of ZnT1 and ZIP8 to manipulate zinc homeostasis and stress-induced cytotoxicity in human neuroblastoma SH-SY5Y cells

Zinc ions (Zn²⁺) are important messenger molecules involved in various physiological functions. To maintain the homeostasis of cytosolic Zn²⁺ concentration ([Zn²⁺]_c), Zrt/Irt-related proteins (ZIPs) and Zn²⁺ transporters (ZnTs) are the two families of proteins responsible for decreasing and increasing the [Zn²⁺]_c, respectively, by fluxing Zn²⁺ across the membranes of the cell and intracellular compartments in opposite directions. Most studies focus on the cytotoxicity incurred by a high concentration of [Zn²⁺]_c and less investigate the [Zn²⁺]_c at physiological levels. Zinc oxide-nanoparticle (ZnO-NP) is blood brain barrier-permeable and elevates the [Zn²⁺]_c to different levels according to the concentrations of ZnO-NP applied. In this study, we mildly elevated the [Zn²⁺]_c by ZnO-NP at concentrations below 1 μg/ml, which had little cytotoxicity, in cultured human neuroblastoma SH-SY5Y cells and characterized the importance of Zn²⁺ transporters in 6-hydroxy dopamine (6-OHDA)-induced cell death. The results show that ZnO-NP at low concentrations elevated the [Zn²⁺]_c transiently in 6 hr, then declined gradually to a basal level in 24 hr. Knocking down the expression levels of ZnT₁ (located mostly at the plasma membrane) and ZIP₈ (present in endosomes and lysosomes) increased and decreased the ZnO-NP-induced elevation of [Zn²⁺]_c, respectively. ZnO-NP treatment reduced the basal levels of reactive oxygen species and Bax/Bcl-2 mRNA ratios; in addition, ZnO-NP decreased the 6-OHDA-induced ROS production, p53 expression, and cell death. These results show that ZnO-NP-induced mild elevation in [Zn²⁺]_c activates beneficial effects in reducing the 6-OHDA-induced cytotoxic effects. Therefore, brain-delivery of ZnO-NP can be regarded as a potential therapy for neurodegenerative diseases.

Assessing the therapeutic potential of Graptopetalum paraguayense on Alzheimer's disease using patient iPSC-derived neurons

Alzheimer’s disease (AD) is the most common type of dementia and also one of the leading causes of death worldwide. However, the underlying mechanisms remain unclear, and currently there is no drug treatment that can prevent or cure AD. Here, we have applied the advantages of using induced pluripotent stem cell (iPSC)-derived neurons (iNs) from AD patients, which are able to offer human-specific drug responsiveness, in order to evaluate therapeutic candidates for AD. Using approach involving an inducible neurogenin-2 transgene, we have established a robust and reproducible protocol for differentiating human iPSCs into glutamatergic neurons. The AD-iN cultures that result have mature phenotypic and physiological properties, together with AD-like biochemical features that include extracellular β-amyloid (Aβ) accumulation and Tau protein phosphorylation. By screening using a gene set enrichment analysis (GSEA) approach, Graptopetalum paraguayense (GP) has been identified as a potential therapeutic agent for AD from among a range of Chinese herbal medicines. We found that administration of a GP extract caused a significantly reduction in the AD-associated phenotypes of the iNs, including decreased levels of extracellular Aβ40 and Aβ42, as well as reduced Tau protein phosphorylation at positions Ser214 and Ser396. Additionally, the effect of GP was more prominent in AD-iNs compared to non-diseased controls. These findings provide valuable information that suggests moving extracts of GP toward drug development, either for treating AD or as a health supplement to prevent AD. Furthermore, our human iN-based platform promises to be a useful strategy when it is used for AD drug discovery.

Cisd2 is essential to delaying cardiac aging and to maintaining heart functions

CDGSH iron-sulfur domain-containing protein 2 (Cisd2) is pivotal to mitochondrial integrity and intracellular Ca2+ homeostasis. In the heart of Cisd2 knockout mice, Cisd2 deficiency causes intercalated disc defects and leads to degeneration of the mitochondria and sarcomeres, thereby impairing its electromechanical functioning. Furthermore, Cisd2 deficiency disrupts Ca2+ homeostasis via dysregulation of sarco/endoplasmic reticulum Ca2+-ATPase (Serca2a) activity, resulting in an increased level of basal cytosolic Ca2+ and mitochondrial Ca2+ overload in cardiomyocytes. Most strikingly, in Cisd2 transgenic mice, a persistently high level of Cisd2 is sufficient to delay cardiac aging and attenuate age-related structural defects and functional decline. In addition, it results in a younger cardiac transcriptome pattern during old age. Our findings indicate that Cisd2 plays an essential role in cardiac aging and in the heart's electromechanical functioning. They highlight Cisd2 as a novel drug target when developing therapies to delay cardiac aging and ameliorate age-related cardiac dysfunction.

Rab18 Collaborates with Rab7 to Modulate Lysosomal and Autophagy Activities in the Nervous System: an Overlapping Mechanism for Warburg Micro Syndrome and Charcot-Marie-Tooth Neuropathy Type 2B

Mutations in RAB18, a member of small G protein, cause Warburg micro syndrome (WARBM), whose clinical features include vision impairment, postnatal microcephaly, and lower limb spasticity. Previously, our Rab18^-/- mice exhibited hind limb weakness and spasticity as well as signs of axonal degeneration in the spinal cord and lumbar spinal nerves. However, the cellular and molecular function of RAB18 and its roles in the pathogenesis of WARBM are still not fully understood. Using immunofluorescence staining and expression of Rab18 and organelle markers, we find that Rab18 associates with lysosomes and actively traffics along neurites in cultured neurons. Interestingly, Rab18^-/- neurons exhibit impaired lysosomal transport. Using autophagosome marker LC3-II, we show that Rab18 dysfunction leads to aberrant autophagy activities in neurons. Electron microscopy further reveals accumulation of lipofuscin-like granules in the dorsal root ganglion of Rab18^-/- mice. Surprisingly, Rab18 colocalizes, cofractionates, and coprecipitates with the lysosomal regulator Rab7, mutations of which cause Charcot-Marie-Tooth (CMT) neuropathy type 2B. Moreover, Rab7 is upregulated in Rab18-deficient neurons, suggesting a compensatory effect. Together, our results suggest that the functions of RAB18 and RAB7 in lysosomal and autophagic activities may constitute an overlapping mechanism underlying WARBM and CMT pathogenesis in the nervous system.

Soluble α-synuclein facilitates priming and fusion by releasing Ca2+ from the thapsigargin-sensitive Ca2+ pool in PC12 cells

α-Synuclein is associated with Parkinson's disease, and is mainly localized in presynaptic terminals and regulates exocytosis, but its physiological roles remain controversial. Here, we studied the effects of soluble and aggregated α-synuclein on exocytosis, and explored the molecular mechanism by which α-synuclein interacts with regulatory proteins, including Rab3A, Munc13-1 (also known as Unc13a) and Munc18-1 (also known as STXBP1), in order to regulate exocytosis. Through fluorescence recovery after photobleaching experiments, overexpressed α-synuclein in PC12 cells was found to be in a monomeric form, which promotes exocytosis. In contrast, aggregated α-synuclein induced by lactacystin treatment inhibits exocytosis. Our results show that α-synuclein is involved in vesicle priming and fusion. α-Synuclein and phorbol 12-myristate 13-acetate (PMA), which is known to enhance vesicle priming mediated by Rab3A, Munc13-1 and Munc18-1, act on the same population of vesicles, but regulate priming independently. Furthermore, the results show a novel effects of α-synuclein on mobilizing Ca²⁺ release from thapsigargin-sensitive Ca²⁺ pools to enhance the ATP-induced [Ca²⁺]_i increase, which enhances vesicle fusion. Our results provide a detailed understanding of the action of α-synuclein during the final steps of exocytosis.

Genome-wide association study identifies novel susceptibility loci for migraine in Han Chinese resided in Taiwan

Background Susceptibility genes for migraine, despite it being a highly prevalent and disabling neurological disorder, have not been analyzed in Asians by genome-wide association study (GWAS). Methods We conducted a two-stage case-control GWAS to identify susceptibility genes for migraine without aura in Han Chinese residing in Taiwan. In the discovery stage, we genotyped 1005 clinic-based Taiwanese migraine patients and 1053 population-based sex-matched controls using Axiom Genome-Wide CHB Array. In the replication stage, we genotyped 27 single-nucleotide polymorphisms with p < 10^-4 in 1120 clinic-based migraine patients and 604 sex-matched normal controls by using Sequenom. Variants at LRP1, TRPM8, and PRDM, which have been replicated in Caucasians, were also genotyped. Results We identified a novel susceptibility locus (rs655484 in DLG2) that reached GWAS significance level for migraine risk in Han Chinese ( p = 1.45 × 10^-12, odds ratio [OR] = 2.42), and also another locus (rs3781545in GFRA1) with suggestive significance ( p = 1.27 × 10^-7, OR = 1.38). In addition, we observed positive association signals with a similar trend to the associations identified in Caucasian GWASs for rs10166942 in TRPM8 (OR = 1.33, 95% confidence interval [CI] = 1.14-1.54, P_permutation = 9.99 × 10^-5; risk allele: T) and rs1172113 in LRP1 (OR = 1.23, 95% CI = 1.04-1.45, P_permutation = 2.9 × 10^-2; risk allele: T). Conclusion The present study is the first migraine GWAS conducted in Han-Chinese and Asians. The newly identified susceptibility genes have potential implications in migraine pathogenesis. DLG2 is involved in glutamatergic neurotransmission, and GFRA1 encodes GDNF receptors that are abundant in CGRP-containing trigeminal neurons. Furthermore, positive association signals for TRPM8 and LRP1 suggest the possibility for common genetic contributions across ethnicities.

Cell death caused by the synergistic effects of zinc and dopamine is mediated by a stress sensor gene Gadd45b - implication in the pathogenesis of Parkinson's disease

The pathogenesis of Parkinson's disease (PD) is not completely understood, Zinc (Zn(2+) ) and dopamine (DA) have been shown to involve in the degeneration of dopaminergic cells. By microarray analysis, we identified Gadd45b as a candidate molecule that mediates Zn(2+) and DA-induced cell death; the mRNA and protein levels of Gadd45b are increased by Zn(2+) treatment and raised to an even higher level by Zn(2+) plus DA treatment. Zn(2+) plus DA treatment-induced PC12 cell death was enhanced when there was over-expression of Gadd45b and was decreased by knock down of Gadd45b. MAPK p38 and JNK signaling was able to cross-talk with Gadd45b during Zn(2+) and DA treatment. The synergistic effects of Zn(2+) and DA on PC12 cell death can be accounted for by an activation of the Gadd45b-induced cell death pathway and an inhibition of p38/JNK survival pathway. Furthermore, the in vivo results show that the levels of Gadd45b protein expression and phosphorylation of p38 were increased in the substantia nigra by the infusion of Zn(2+) /DA in the mouse brain and the level of Gadd45b mRNA is significantly higher in the substantia nigra of male PD patients than normal controls. The novel role of Gadd45b and its interactions with JNK and p38 will help our understanding of the pathogenesis of PD and help the development of future treatments for PD. Zinc and dopamine are implicated in the degeneration of dopaminergic neurons. We previously demonstrated that zinc and dopamine induced synergistic effects on PC12 cell death. Results from this study show that these synergistic effects can be accounted for by activation of the Gadd45b-induced cell death pathway and inhibition of the p38/JNK survival pathway. We provide in vitro and in vivo evidence to support a novel role for Gadd45b in the pathogenesis of Parkinson's disease.

Susceptible genes of restless legs syndrome in migraine

Objective Several genetic variants have been found to increase the risk of restless legs syndrome (RLS). The aim of the present study was to determine if these genetic variants were also associated with the comorbidity of RLS and migraine in patients. Methods Thirteen single-nucleotide polymorphisms (SNPs) at six RLS risk loci ( MEIS1, BTBD9, MAP2K5, PTPRD, TOX3, and an intergenic region on chromosome 2p14) were genotyped in 211 migraine patients with RLS and 781 migraine patients without RLS. Association analyses were performed for the overall cohort, as well as for the subgroups of patients who experienced migraines with and without aura and episodic migraines (EMs) vs. chronic migraines (CMs). In order to verify which genetic markers were potentially related to the incidence of RLS in migraine patients, multivariate regression analyses were also performed. Results Among the six tested loci, only MEIS1 was significantly associated with RLS. The most significant SNP of MEIS1, rs2300478, increased the risk of RLS by 1.42-fold in the overall cohort ( p = 0.0047). In the subgroup analyses, MEIS1 augmented the risk of RLS only in the patients who experienced EMs (odds ratio (OR) = 1.99, p = 0.0004) and not those experiencing CMs. Multivariate regression analyses further showed that rs2300478 in MEIS1 (OR = 1.39, p = 0.018), a CM diagnosis (OR = 1.52, p = 0.022), and depression (OR = 1.86, p = 0.005) were independent predictors of RLS in migraine. Conclusions MEIS1 variants were associated with an increased risk of RLS in migraine patients. It is possible that an imbalance in iron homeostasis and the dopaminergic system may represent a link between RLS incidence and migraines.

Calcium regulation in mouse mesencephalic neurons-Differential roles of Na(+)/Ca(2+) exchanger, mitochondria and endoplasmic reticulum

Midbrain dopaminergic (DA) neurons are the key to finely tune the voluntary movement, habit and motivation. The progressive and selective degeneration of these neurons is a pathological hallmark of Parkinson's disease (PD). The susceptibility of DA neurons in the SNpc may result from differences in how Ca(2+) is handled. However, very little information is available about the mechanisms involved in the regulation of intracellular Ca(2+) concentration ([Ca(2+)]i) in DA neurons. In this study, the relative contributions of various Na(+)/Ca(2+) exchangers and their interplay with internal Ca(2+) stores, endoplasmic reticulum (ER) and the mitochondria, in the regulation of the [Ca(2+)]i of mouse mesencephalic neurons were characterized. Both the K(+)-dependent Na(+)/Ca(2+) exchanger (NCKX) and the K(+)-independent Na(+)/Ca(2+) exchanger (NCX) can be detected and are functional in DA and non-DA neurons. NCX accounts for the larger component of Na(+)/Ca(2+) exchange activity. Single-cell RT-PCR analysis showed each individual neuron expressed a distinct set of the Na(+)/Ca(2+) exchangers. Furthermore, the Na(+)/Ca(2+) exchangers play prominent roles in removing [Ca(2+)]i induced by glutamate but not [Ca(2+)]i induced by depolarization. The mitochondria serve as a major Ca(2+) sink and are functionally located close to NCX. In contrast, the ER is functionally located close to NCKX and acts primarily as a Ca(2+) source with marginal effects. This study reveals that the Na(+)/Ca(2+) exchangers, the ER and the mitochondria, which cooperate interactively, act similarly when regulating [Ca(2+)]i in mesencephalic DA and non-DA neurons. The heterogeneous expression of multiple types of Na(+)/Ca(2+) exchangers and the quantitative differences found in [Ca(2+)]i regulation, together with other risk factors specific to DA neurons such as dopamine oxidation resulting in oxidative stress, may drive these cells to undergo selective degeneration.

ENU mutagenesis identifies mice modeling Warburg Micro Syndrome with sensory axon degeneration caused by a deletion in Rab18

Mutations in the gene of RAB18, a member of Ras superfamily of small G-proteins, cause Warburg Micro Syndrome (WARBM) which is characterized by defective neurodevelopmental and ophthalmological phenotypes. Despite loss of Rab18 had been reported to induce disruption of the endoplasmic reticulum structure and neuronal cytoskeleton organization, parts of the pathogenic mechanism caused by RAB18 mutation remain unclear. From the N-ethyl-N-nitrosourea (ENU)-induced mutagenesis library, we identified a mouse line whose Rab18 was knocked out. This Rab18(-/-) mouse exhibited stomping gait, smaller testis and eyes, mimicking several features of WARBM. Rab18(-/-) mice were obviously less sensitive to pain and touch than WT mice. Histological examinations on Rab18(-/-) mice revealed progressive axonal degeneration in the optic nerves, dorsal column of the spinal cord and sensory roots of the spinal nerves while the motor roots were spared. All the behavioral and pathological changes that resulted from abnormalities in the sensory axons were prevented by introducing an extra copy of Rab18 transgene in Rab18(-/-) mice. Our results reveal that sensory axonal degeneration is the primary cause of stomping gait and progressive weakness of the hind limbs in Rab18(-/-) mice, and optic nerve degeneration should be the major pathology of progressive optic atrophy in children with WARBM. Our results indicate that the sensory nervous system is more vulnerable to Rab18 deficiency and WARBM is not only a neurodevelopmental but also neurodegenerative disease.

Primary skin closure after damage control laparotomy

Background

Damage control laparotomy (DCL) is used widely in the management of patients with traumatic injuries but carries significant morbidity. Surgical-site infection (SSI) also carries potential morbidity, increased costs and prolonged hospital stay. The aim of this study was to determine whether primary skin closure after DCL increases the risk of SSI.

Methods

This was a retrospective institutional review of injured patients undergoing DCL between 2004 and 2012. Outcomes of patients who had primary skin closure at the time of fascial closure were compared with those of patients whose skin wound was left open to heal by secondary intention. The association between skin closure and SSI was evaluated using propensity score-adjusted multivariable logistic regression.

Results

Of 510 patients who underwent DCL, primary fascial closure was achieved in 301. Among these, 111 (36·9 per cent) underwent primary skin closure and in 190 (63·1 per cent) the skin wound was left open. Fascial closure at the initial take-back surgery was associated with having skin closure (P &lt; 0·001), and colonic injury was associated with leaving the skin open (P = 0·002). On multivariable analysis, primary skin closure was associated with an increased risk of abdominal SSI (P = 0·020), but not fascial dehiscence (P = 0·446). Of patients receiving skin closure, 85·6 per cent did not develop abdominal SSI and were spared the morbidity of managing an open wound at discharge.

Conclusion

Primary skin closure after DCL is appropriate but may be associated with an increased risk of SSI.

A novel TFG mutation causes Charcot-Marie-Tooth disease type 2 and impairs TFG function

OBJECTIVE

To describe a novel mutation in TRK-fused gene (TFG) as a new cause of dominant axonal Charcot-Marie-Tooth disease (CMT) identified by exome sequencing and further characterized by in vitro functional studies.

METHODS

Exome sequencing and linkage analysis were utilized to investigate a large Taiwanese family with a dominantly inherited adult-onset motor and sensory axonal neuropathy in which mutations in common CMT2-implicated genes had been previously excluded. Functional effects of the mutant gene products were investigated in vitro.

RESULTS

Exome sequencing of 2 affected individuals in this family revealed a novel heterozygous mutation, c.806G>T (p.Gly269Val), in TFG that perfectly cosegregates with the CMT2 phenotype in all 27 family members. This mutation occurs at an evolutionarily conserved residue and is absent in the 1,140 ethnically matched control chromosomes. Genome-wide linkage study also supported its disease-causative role. Cell transfection studies showed that the TFG p.Gly269Val mutation increased the propensity of TFG proteins to form aggregates, resulting in sequestration of both mutant and wild-type TFG proteins and might thus deplete functional TFG molecules. The secreted Gaussia luciferase reporter assay demonstrated that inhibition of endogenous TFG compromised the protein secretion pathways, which could only be rescued by expressing wild-type TFG but not the p.Gly269Val altered proteins. TFG mutation was not found in 55 additional unrelated patients with CMT2, suggesting its rarity.

CONCLUSION

This study identifies a new cause of dominant CMT2 and highlights the importance of TFG in the protein secretory pathways that are essential for proper functioning of the human peripheral nervous system.

Circular closure is associated with the lowest rate of surgical site infection following stoma reversal: a systematic review and multiple treatment meta-analysis

AIM

Stoma reversal is frequently complicated by surgical site infection (SSI). To reduce SSI, several techniques for skin closure have been studied, with no agreement on which is best. The aim of this study was to identify the skin closure technique associated with the lowest rate of SSI following stoma reversal.

METHOD

We systematically searched MEDLINE (PubMed and OvidSP), Scopus and clinical registries from 1 January 1980 to 24 March 2012, and included original reports on adult patients following stoma reversal. A network of treatments was created to map the comparisons between skin closure techniques, including primary closure, primary closure with a drain, secondary closure, delayed primary closure, loose primary closure and circular closure. Pairwise meta-analyses were performed for all available direct comparisons of closure types and heterogeneity was assessed. A multiple-treatments meta-analysis was conducted to estimate relative treatment effects between competing closure types (reported as an odds ratio with 95% credible interval, and a probability that each treatment is best). Several sensitivity analyses were performed.

RESULTS

Fifteen studies were identified with a total of 2921 cases of stoma reversal. Overall, study quality was poor with observed low (one study), moderate (seven studies) and high (seven studies) risk of bias. Circular closure was associated with the lowest SSI risk (OR 0.12; 95% CI 0.02-0.40) and was the best of six skin closure techniques (probability of being best = 68.9%). Circular closure remained the best after sensitivity analyses.

CONCLUSION

This study showed that circular closure is the best skin closure technique after stoma reversal in terms of SSI rate, but the quality of supporting evidence is limited, precluding definite conclusions.

Cisd2 modulates the differentiation and functioning of adipocytes by regulating intracellular Ca2+ homeostasis

CISD2 is a causative gene associated with Wolfram syndrome (WFS). However, it remains a mystery as to how the loss of CISD2 causes metabolic defects in patients with WFS. Investigation on the role played by Cisd2 in specific cell types may help us to resolve these underlying mechanisms. White adipose tissue (WAT) is central to the maintenance of energy metabolism and glucose homeostasis in humans. In this study, adipocyte-specific Cisd2 knockout (KO) mice showed impairment in the development of epididymal WAT (eWAT) in the cell autonomous manner. A lack of Cisd2 caused defects in the biogenesis and function of mitochondria during differentiation of adipocytes in vitro. Insulin-stimulated glucose uptake and secretion of adiponectin by the Cisd2 KO adipocytes were decreased. Moreover, Cisd2 deficiency increased the cytosolic level of Ca(2+) and induced Ca(2+)-calcineurin-dependent signaling that inhibited adipogenesis. Importantly, Cisd2 was found to interact with Gimap5 on the mitochondrial and ER membranes and thereby modulate mitochondrial Ca(2+) uptake associated with the maintenance of intracellular Ca(2+) homeostasis in adipocytes. Thus, it would seem that Cisd2 plays an important role in intracellular Ca(2+) homeostasis, which is required for the differentiation and functioning of adipocytes as well as the regulation of glucose homeostasis in mice.

Inhibition of reverse-mode sodium-calcium exchanger activity and apoptosis by levosimendan in human cardiomyocyte progenitor cell-derived cardiomyocytes after anoxia and reoxygenation

Levosimendan, a known calcium sensitizer with positive inotropic and vasodilating properties, might also be cardioprotective during ischemia-reperfusion (I/R) insult. Its effects on calcium homeostasis and apoptosis in I/R injury remain unclear. Na(+)/Ca(2+) exchanger (NCX) is a critical mediator of calcium homeostasis in cardiomyocytes, with reverse-mode NCX activity responsible for intracellular calcium overload and apoptosis of cardiomyocytes during I/R. We probed effects and underlying mechanisms of levosimendan on apoptosis and NCX activity in cultured human cardiomyocyte progenitor cells (CPC)-derived cardiomyocytes undergoing anoxia-reoxygenation (A/R), simulating I/R in vivo. Administration of levosimendan decreased apoptosis of CPC-derived cardiomyocytes induced by A/R. The increase in reverse-mode NCX activity after A/R was curtailed by levosimendan, and NCX1 was translocated away from the cell membrane. Concomitantly, endoplasmic reticulum (ER) stress response induced by A/R was attenuated in CPC-derived cardiomycytes treated with NCX-targeted siRNA or levosimendan, with no synergistic effect between treatments. Results indicated levosimendan inhibited reverse-mode NCX activity to protect CPC-derived cardiomyocytes from A/R-induced ER stress and cell death.

Abstract P1-09-14: Relationship between socioeconomic status, race, and breast cancer clinical stage at presentation

Introduction: Racial and ethnic minority breast cancer patients present with later clinical stage at diagnosis, which may be due to lack of access to care due to poor socioeconomic status (SES). Our hypothesis was that the racial gap in clinical stage at breast cancer presentation would be eliminated after adjustment for SES.

Methods: Retrospective review was performed of breast cancer (excluding ductal carcinoma in situ) patients from 10 hospitals in Harris County Texas between 2002 and 2011. Demographic and clinical information was recorded. Clinical stage was calculated based on data from the institutional tumor registry and electronic medical record. Zip code-based SES data, including mean household income and percentage of households receiving social support, were downloaded from www.census.gov. A multivariate ordered logistic regression clustered by hospital was used to identify predictors of clinical stage.

Results: Of 3084 breast cancer patients, the mean age at diagnosis was 59 ± 14 years. The cohort included 1873 Caucasian (61%), 519 African-Americans (17%), 353 Hispanics (11%), and 339 Asian/others (11%). Age, race, mean household income, and percentage of household receiving social support were predictive of clinical stage at presentation (p&lt;0.05).

Ordered Logistic RegressionVariableOdds RatioSEp-value95% CIMean Income0.998.2 e-060.0010.98 - 0.99% Social Support1.010.0020.0021.00 - 1.01Age0.980.0020.0410.97- 0.99Race    African-American4.581.220.0002.72 - 7.72Hispanic1.991.260.2730.58 - 6.89Asian/other1.450.760.4730.52 - 4.04Caucasian = referent value for Race, SE = standard error, CI = confidence interval

The largest racial gap was observed between African-Americans and Caucasians. African Americans from areas with a mean income up to $180K still had a lower predicted probability of presenting with clinical stage 1a disease than the Caucasians from the poorest mean income areas (&lt;$5K). African Americans from the highest mean income areas (&gt; $305K) still had a higher probability of presenting with clinical stage 4 disease as Caucasians from areas with a mean income as low as $100K.

Conclusion: Both African-American race and residence in a low SES zip code contribute independently to late clinical stage at presentation among breast cancer patients. Both genetic and social factors may play a role in this disparity. Addressing factors related to just race or low SES status alone is unlikely to improve outcomes for African-Americans from low SES zip codes.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-09-14.

Exome sequencing identifies GNB4 mutations as a cause of dominant intermediate Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of inherited neuropathies. Mutations in approximately 45 genes have been identified as being associated with CMT. Nevertheless, the genetic etiologies of at least 30% of CMTs have yet to be elucidated. Using a genome-wide linkage study, we previously mapped a dominant intermediate CMT to chromosomal region 3q28-q29. Subsequent exome sequencing of two affected first cousins revealed heterozygous mutation c.158G>A (p.Gly53Asp) in GNB4, encoding guanine-nucleotide-binding protein subunit beta-4 (Gβ4), to cosegregate with the CMT phenotype in the family. Further analysis of GNB4 in an additional 88 unrelated CMT individuals uncovered another de novo mutation, c.265A>G (p.Lys89Glu), in this gene in one individual. Immunohistochemistry studies revealed that Gβ4 was abundant in the axons and Schwann cells of peripheral nerves and that expression of Gβ4 was significantly reduced in the sural nerve of the two individuals carrying the c.158G>A (p.Gly53Asp) mutation. In vitro studies demonstrated that both the p.Gly53Asp and p.Lys89Glu altered proteins impaired bradykinin-induced G-protein-coupled-receptor (GPCR) signaling, which was facilitated by the wild-type Gβ4. This study identifies GNB4 mutations as a cause of CMT and highlights the importance of Gβ4-related GPCR signaling in peripheral-nerve function in humans.

Regulation of sodium-calcium exchanger activity by creatine kinase

It has been shown that in rat heart NCX1 exists in a macromolecular -complex including PKA, PKA-anchoring protein, PKC, and phosphatases PP1 and PP2A. In addition, several lines of evidence suggest that the interactions of the exchanger with other molecules are closely associated with its function in regulation of [Ca(2+)](i). NCX contains a large intracellular loop (NCXIL) that is responsible for regulating NCX activity. We used the yeast two-hybrid method to screen a human heart cDNA library and found that the C-terminal region of sarcomeric mitochondrial creatine kinase (sMiCK) interacted with NCX1IL. Among the four creatine kinase (CK) isozymes, both sMiCK and the muscle-type cytosolic creatine kinase (CKM) co-immunoprecipitated with NCX1. Both sMiCK and CKM were able to produce a recovery in the decreased NCX1 activity that was lost under energy-compromised conditions. This regulation is mediated through a putative PKC phosphorylation site of sMiCK and CKM. The catalytic activity of sMiCK and CKM is not required for their regulation of NCX1 activity. Our results suggest a novel mechanism for the regulation of NCX1 activity and a novel role for CK.

Automatic morphological subtyping reveals new roles of caspases in mitochondrial dynamics

Morphological dynamics of mitochondria is associated with key cellular processes related to aging and neuronal degenerative diseases, but the lack of standard quantification of mitochondrial morphology impedes systematic investigation. This paper presents an automated system for the quantification and classification of mitochondrial morphology. We discovered six morphological subtypes of mitochondria for objective quantification of mitochondrial morphology. These six subtypes are small globules, swollen globules, straight tubules, twisted tubules, branched tubules and loops. The subtyping was derived by applying consensus clustering to a huge collection of more than 200 thousand mitochondrial images extracted from 1422 micrographs of Chinese hamster ovary (CHO) cells treated with different drugs, and was validated by evidence of functional similarity reported in the literature. Quantitative statistics of subtype compositions in cells is useful for correlating drug response and mitochondrial dynamics. Combining the quantitative results with our biochemical studies about the effects of squamocin on CHO cells reveals new roles of Caspases in the regulatory mechanisms of mitochondrial dynamics. This system is not only of value to the mitochondrial field, but also applicable to the investigation of other subcellular organelle morphology.

Mitochondria are “cellular power plants” that synthesize adenosine triphosphate (ATP) from degradation of nutrients, providing chemical energy for cellular activities. In addition, mitochondria are involved in a range of other cellular processes, such as signaling, cell differentiation, cell death, cell cycle and cell growth. Dysfunctional mitochondrial dynamics have been linked to several neurodegenerative diseases, and may play a role in the aging process. Previous studies on the correlation between mitochondrial morphological changes and pathological processes involve mostly manual or semi-automated classification and quantification of morphological features, which introduces biases and inconsistency, and are labor intensive. In this work we have developed an automated quantification system for mitochondrial morphology, which is able to extract and distinguish six representative morphological subtypes within cells. Using this system, we have analyzed 1422 cells and extracted more than 200 thousand individual mitochondrion, and calculated morphological statistics for each cell. From the numerical results we were able to derive new biological conclusions about mitochondrial morphological dynamics. With this new system, investigations of mitochondrial morphology can be scaled up and objectively quantified, allowing standardization of morphological distinctions and replicability between experiments. This system will facilitate future research on the relation between subcellular morphology and various physiological processes.

Involvement of Rab3A in vesicle priming during exocytosis: interaction with Munc13-1 and Munc18-1

Rab3A is a small G-protein of the Rab family that is involved in the late steps of exocytosis. Here, we studied the role of Rab3A and its relationship with Munc13-1 and Munc18-1 during vesicle priming. Phorbol 12-myristate 13-acetate (PMA) is known to enhance the percentage of fusion-competent vesicles and this is mediated by protein kinase C (PKC)-independent Munc13-1 activation and PKC-dependent dissociation of Munc18-1 from syntaxin 1a. Our results show that the effects of PMA varied in cells overexpressing Rab3A or mutants of Rab3A and in cells with Rab3A knockdown. When Munc13-1 was overexpressed in Rab3A knockdown cells, secretion was completely inhibited. In cells overexpressing a Rab-interacting molecule (RIM)-binding deficient Munc13-1 mutant, 128-Munc13-1, the effects of Rab3A on PMA-induced secretion was abolished. The effect of PMA, which disappeared in cells overexpressing GTP-Rab3A (Q81L), could be reversed by co-expressing Munc18-1 but not its mutant R39C, which is unable to bind to syntaxin 1a. In cells overexpressing Munc18-1, manipulation of Rab3A activity had no effect on secretion. Finally, Munc18-1 enhanced the dissociation of Rab3A, and such enhancement correlated with exocytosis. In summary, our results support the hypothesis that the Rab3A cycle is coupled with the activation of Munc13-1 via RIM, which accounts for the regulation of secretion by Rab3A. Munc18-1 acts downstream of Munc13-1/RIM/Rab3A and interacts with syntaxin 1a allowing vesicle priming. Furthermore, Munc18-1 promotes Rab3A dissociation from vesicles, which then results in fusion.

Regulation of sodium-calcium exchanger activity by creatine kinase under energy-compromised conditions

Na(+)/Ca(2+) exchanger (NCX) is one of the major mechanisms for removing Ca(2+) from the cytosol especially in cardiac myocytes and neurons, where their physiological activities are triggered by an influx of Ca(2+). NCX contains a large intracellular loop (NCXIL) that is responsible for regulating NCX activity. Recent evidence has shown that proteins, including kinases and phosphatases, associate with NCX1IL to form a NCX1 macromolecular complex. To search for the molecules that interact with NCX1IL and regulate NCX1 activity, we used the yeast two-hybrid method to screen a human heart cDNA library and found that the C-terminal region of sarcomeric mitochondrial creatine kinase (sMiCK) interacted with NCX1IL. Moreover, both sMiCK and the muscle-type creatine kinase (CKM) coimmunoprecipitated with NCX1 using lysates of cardiacmyocytes and HEK293T cells that transiently expressed NCX1 and various creatine kinases. Both sMiCK and CKM were able to produce a recovery in the decreased NCX1 activity that was lost under energy-compromised conditions. This regulation is mediated through a putative PKC phosphorylation site of sMiCK and CKM. The autophosphorylation and the catalytic activity of sMiCK and CKM are not required for their regulation of NCX1 activity. Our results suggest a novel mechanism for the regulation of NCX1 activity.

Cutting Edge: mechanical forces acting on T cells immobilized via the TCR complex can trigger TCR signaling

Engagement of the TCR by antigenic peptides presented by the MHC activates specific T cells to control infections. Recent theoretical considerations have suggested that mechanical forces acting on the TCR may be important for receptor triggering. In this study, we directly tested the hypothesis that physical forces acting on the TCR can initiate signaling in T cells by micromanipulation of individual T cells bound to artificial APCs expressing engineered TCR ligands. We find that mechanical forces acting on T cells bound to APCs via the TCR complex but not other surface receptors can initiate signaling in T cells in an Src kinase-dependent fashion. Our data indicate that T cells are mechanically sensitive when coupled to APCs by the TCR and indicates that the TCR may act as a mechanosensor. Our data provide new insight into TCR function.

Characterization of Ca2+ signaling pathways in mouse adrenal medullary chromaffin cells

In the present study, we characterized the Ca2+ responses and secretions induced by various secretagogues in mouse chromaffin cells. Activation of the acetylcholine receptor (AChR) by carbachol induced a transient intracellular Ca2+ concentration ([Ca2+](i)) increase followed by two phases of [Ca2+](i) decay and a burst of exocytic events. The contribution of the subtypes of AChRs to carbachol-induced responses was examined. Based on the results obtained by stimulating the cells with the nicotinic receptor (nAChR) agonist, 1,1-dimethyl-4-phenylpiperazinium iodide, high K(+) and the effects of thapsigargin, it appears that activation of nAChRs induces an extracellular Ca2+ influx, which in turn activate Ca(2+)-induced Ca2+ release via the ryanodine receptors. Muscarine, a muscarinic receptor (mAChRs) agonist, was found to induce [Ca2+](i) oscillation and sustained catecholamine release, possibly by activation of both the receptor- and store-operated Ca2+ entry pathways. The RT-PCR results showed that mouse chromaffin cells are equipped with messages for multiple subtypes of AChRs, ryanodine receptors and all known components of the receptor- and store-operated Ca2+ entry. Furthermore, results obtained by directly monitoring endoplasmic reticulum (ER) and mitochondrial Ca2+ concentration and by disabling mitochondrial Ca2+ uptake suggest that the ER acts as a Ca2+ source, while the mitochondria acts as a Ca2+ sink. Our results show that both nAChRs and mAChRs contribute to the initial carbachol-induced [Ca2+](i) increase which is further enhanced by the Ca2+ released from the ER mediated by Ca(2+)-induced Ca2+ release and mAChR activation. This information on the Ca2+ signaling pathways should lay a good foundation for future studies using mouse chromaffin cells as a model system.

Morphological filter improve the efficiency of automated tracking of secretory vesicles with various dynamic properties

Membrane trafficking is a very important physiological process involved in protein transport, endocytosis, and exocytosis. The functions of vesicles are strongly correlated with various spatial dynamic properties of vesicles, including their types of movements and morphology. Several methods are used to quantify such dynamic properties, but most of them are specific to particular populations of vesicles. We previously developed the so-called PTrack system for quantifying the dynamics of secretory vesicles near the cell surface, which are small and move slowly. To improve the system performance in quantifying large and fast-moving vesicles, we firstly combined morphological filter with two-threshold image processing techniques to locate granules of various sizes. Next, Kalman filtering was used to improve the performance in tracking fast-moving and large granules. Performance evaluation by using simulation image sequences shown that the new system, called PTrack II, yields better tracking accuracy. The tracking system was validated using time-lapse images of insulin granules in betaTC3 cells, which revealed that PTrack II could track better than PTrack, averaged accuracy up to 56%. The overall tracking results indicate that PTrack II is better at tracking vesicles with various dynamic properties, which will facilitate the acquisition of more-complete information on vesicle dynamics.

Physical forces can trigger T cell receptor signaling (35.10)

Engagement of the T cell receptor (TCR) by antigenic peptides presented by the major histocompatibility complex (pMHC) activates specific T cells to control infections. The mechanism of TCR triggering, however, has remained obscure. Here, using micromanipulation of individual T cells, we show that physical forces acting on the TCR can induce calcium mobilization in a Lck-dependent manner. Investigation of artificial antigen-presenting cells (APCs) expressing engineered TCR ligands supports a model in which intercellular tension on the TCR generated during ligand engagement can initiate signaling in T cells. Furthermore, specific interactions between intercellular adhesion molecule-1 (ICAM-1) on APCs and the integrin LFA-1 on T cells may regulate tension to set the threshold for TCR triggering during ligand engagement.

In-depth fluorescence lifetime imaging analysis revealing SNAP25A-Rabphilin 3A interactions

The high sensitivity and spatial resolution enabled by two-photon excitation fluorescence lifetime imaging microscopy/fluorescence resonance energy transfer (2PE-FLIM/FRET) provide an effective approach that reveals protein-protein interactions in a single cell during stimulated exocytosis. Enhanced green fluorescence protein (EGFP)-labeled synaptosomal associated protein of 25 kDa (SNAP25A) and red fluorescence protein (mRFP)-labeled Rabphillin 3A (RPH3A) were co-expressed in PC12 cells as the FRET donor and acceptor, respectively. The FLIM images of EGFP-SNAP25A suggested that SNAP25A/RPH3A interaction was increased during exocytosis. In addition, the multidimensional (three-dimensional with time) nature of the 2PE-FLIM image datasets can also resolve the protein interactions in the z direction, and we have compared several image analysis methods to extract more accurate and detailed information from the FLIM images. Fluorescence lifetime was fitted by using one and two component analysis. The lifetime FRET efficiency was calculated by the peak lifetime (taupeak) and the left side of the half-peak width (tau1/2), respectively. The results show that FRET efficiency increased at cell surface, which suggests that SNAP25A/RPH3A interactions take place at cell surface during stimulated exocytosis. In summary, we have demonstrated that the 2PE-FLIM/FRET technique is a powerful tool to reveal dynamic SNAP25A/RPH3A interactions in single neuroendocrine cells.

The co-presence of Na+/Ca2+-K+ exchanger and Na+/Ca2+ exchanger in bovine adrenal chromaffin cells

We have previously shown that there is high Na(+)/Ca(2+) exchange (NCX) activity in bovine adrenal chromaffin cells. In this study, by monitoring the [Ca(2+)](i) change in single cells and in a population of chromaffin cells, when the reverse mode of exchanger activity has been initiated, we have shown that the NCX activity is enhanced by K(+). The K(+)-enhanced activity accounted for a significant proportion of the Na(+)-dependent Ca(2+) uptake activity in the chromaffin cells. The results support the hypothesis that both NCX and Na(+)/Ca(2+)-K(+) exchanger (NCKX) are co-present in chromaffin cells. The expression of NCKX in chromaffin cells was further confirmed using PCR and northern blotting. In addition to the plasma membrane, the exchanger activity, measured by Na(+)-dependent (45)Ca(2+) uptake, was also present in membrane isolated from the chromaffin granules enriched fraction and the mitochondria enriched fraction. The results support that both NCX and NCKX are present in bovine chromaffin cells and that the regulation of [Ca(2+)](i) is probably more efficient with the participation of NCKX.

Automated recognition system to classify subcellular protein localizations in images of different cell lines acquired by different imaging systems

Systemic analysis of subcellular protein localization (location proteomics) provides clues for understanding gene functions and physiological condition of the cells. However, recognition of cell images of subcellular structures highly depends on experience and becomes the rate-limiting step when classifying subcellular protein localization. Several research groups have extracted specific numerical features for the recognition of subcellular protein localization, but these recognition systems are restricted to images of single particular cell line acquired by one specific imaging system and not applied to recognize a range of cell image sources. In this study, we establish a single system for automated subcellular structure recognition to identify cell images from various sources. Two different sources of cell images, 317 Vero (http://gfp-cdna.embl.de) and 875 CHO cell images of subcellular structures, were used to train and test the system. When the system was trained by a single source of images, the recognition rate is high and specific to the trained source. The system trained by the CHO cell images gave high average recognition accuracy for CHO cells of 96%, but this was reduced to 46% with Vero images. When we trained the system using a mixture of CHO and Vero cell images, an average accuracy of recognition reached 86.6% for both CHO and Vero cell images. The system can reject images with low confidence and identify the cell images correctly recognized to avoid manual reconfirmation. In summary, we have established a single system that can recognize subcellular protein localizations from two different sources for location-proteomic studies. studies.

Tetramethylpyrazine inhibits activities of glioma cells and glutamate neuro-excitotoxicity: potential therapeutic application for treatment of gliomas

We tested the herbal extract 2,3,5,6-tetramethylpyrazine (TMP) for possible therapeutic efficacy against a glioma cell line and against gliomas transplanted into rat brains. In the cultured glioma cells, 50 muM TMP significantly inhibited glutamate-induced increase in intracellular calcium. Significant cell damage (30%) and proliferation suppression (10%), however, occurred only at higher concentrations (200-400 microM). Gliomaneuronal co-culturing resulted in significant neuronal damage and higher proliferation of the glioma cells (140%) compared with single cultures. Low concentrations of TMP (< or =200 microM) attenuated the neuronal damage, suppressed glioma migration, and decreased glioma proliferation in the neuronal-glioma co-culture. Gliomas transplanted into the frontal cortical area exhibited high proliferation, with untreated rats dying 10-23 days later. TMP treatment inhibited tumor growth and significantly extended survival time. The results indicate that TMP can suppress glioma activity, including growth, and protect neurons against glioma-induced excitotoxicity, suggesting that TMP may have therapeutic potential in the treatment of malignant gliomas.

Detection of the interaction between SNAP25 and rabphilin in neuroendocrine PC12 cells using the FLIM/FRET technique

Exocytosis has been proposed to contain four sequential steps, namely docking, priming, fusion, and recycling, and to be regulated by various proteins-protein interactions. Synaptosomal-associated protein of 25 kDa (SNAP25) has recently been found to bind rabphilin, the Rab3A specific binding protein, in vitro. However, it is still unclear whether SNAP25 and rabphilin interact during exocytosis within cells in vivo. This problem was addressed by the integration of fluorescence resonance energy transfer (FRET) with high sensitivity fluorescence lifetime imaging microscopy (FLIM) to observe this protein-protein interaction. Enhanced green fluorescence protein-labeled SNAP25 (donor) and red fluorescence protein-labeled rabphilin (acceptor) were expressed in neuroendocrine PC12 cells as a FRET pair and ATP stimulation was carried out for various durations. With 10 s stimulation, a 0.17-ns left shift of the lifetime peak was found when compared with donor only. Analysis of the lifetime image further suggested that the lifetime recovered to a similar level as the donor only in a time dependent manner. Four-dimensional (4D) images by FLIM provided useful information indicating that the interaction of SNAP25 and rabphilin occurred particularly within optical sections near cell membrane. Together the results suggest that SNAP25 bound rabphilin loosely at docking step before exocytosis and the binding became tighter at the very start of exocytosis. Finally, these two proteins dissociated after stimulation. To our knowledge, this is the first report to demonstrate the interaction of SNAP25 and rabphilin in situ using the FLIM-FRET technique within neuroendocrine cells.

Open reading frame 8a of the human severe acute respiratory syndrome coronavirus not only promotes viral replication but also induces apoptosis

Background. A unique genomic difference between human and civet severe acute respiratory syndrome coronaviruses (SARS-CoVs) is that the former has a deletion of 29 nucleotides from open reading frame (orf) 8d that results in the generation of orf8a and orf8b. The objectives of the present study were to analyze antibody reactivity to ORF8a in patients with SARS and to elucidate the function of ORF8a.

Methods. Western-blot and immunofluorescent antibody assays were used to detect anti-ORF8a antibody. SARS-CoV HKU39849 was used to infect stable clones expressing ORF8a and cells transfected with small interfering RNA (siRNA). The virus loads (VLs) and cytopathic effects (CPEs) were recorded. Confocal microscopy and several mitochondria-related tests were used to study the function of ORF8a.

Results. Two (5.4%) of 37 patients with SARS had anti-ORF8a antibodies. The VLs in the stable clones expressing ORF8a were significantly higher than those in control subjects 5 days after infection. siRNA against orf8a significantly reduced VLs and interrupted the CPE. ORF8a was found to be localized in mitochondria, and overexpression resulted in increases in mitochondrial transmembrane potential, reactive oxygen species production, caspase 3 activity, and cellular apoptosis.

Conclusions. ORF8a not only enhances viral replication but also induces apoptosis through a mitochondria-dependent pathway.

An automated tracking system to measure the dynamic properties of vesicles in living cells

Recent technological improvements have made it possible to examine the dynamics of individual vesicles at a very high temporal and spatial resolution. Quantification of the dynamic properties of secretory vesicles is labor-intensive and therefore it is crucial to develop software to automate the process of analyzing vesicle dynamics. Dual-threshold and binary image conversion were applied to enhance images and define the areas of objects of interest that were to be tracked. The movements, changes in fluorescence intensity, and changes in the area of each tracked object were measured using a new software system named the Protein Tracking system (PTrack). Simulations revealed that the system accurately recognized tracked objects and measured their dynamic properties. Comparison of the results from tracking real time-lapsed images manually with those automatically obtained using PTrack revealed similar patterns for changes in fluorescence intensity and a high accuracy (<89%). According to tracking results, PTrack can distinguish different vesicular organelles that are similar in shape, based on their unique dynamic properties. In conclusion, the novel tracking system, PTrack, should facilitate automated quantification of the dynamic properties of vesicles that are important when classifying vesicular protein locations.

Hyperglycemia and morbidity and mortality in extremely low birth weight infants

OBJECTIVE

The purpose of this study was to determine the association between hyperglycemia and mortality and late-onset infections (>72 h) in extremely low birth weight (ELBW) infants.

STUDY DESIGN

Retrospective analysis of a prospective cohort study of 201 ELBW infants who survived greater than 3 days after birth. Mean morning glucose levels were categorized as normoglycemia (<120 mg/dl), mild-moderate hyperglycemia (120 to 179 mg/dl) and severe hyperglycemia (> or =180 mg/dl). Hyperglycemia was further divided into early (first 3 days of age) and persistent (first week of age). Logistic regression was performed to assess whether hyperglycemia was associated with either mortality or late-onset culture-proven infection, measured after 3 and 7 days of age.

RESULTS

Adjusting for age, the odds ratio (OR) for either dying or developing a late infection was 5.07 (95% confidence interval (CI): 1.06 to 24.3) for infants with early severe hyperglycemia and 6.26 (95% CI: 0.73 to 54.0) for infants with persistent severe hyperglycemia. Adjusting for age, both severe early and persistent hyperglycemia were associated with increased mortality. Among survivors, there was no significant association between hyperglycemia and length of mechanical ventilation or length of hospital stay. Persistent severe hyperglycemia was associated with the development of Stage II/III necrotizing enterocolitis, after adjusting for age and male gender (OR: 9.49, 95% CI: 1.52 to 59.3).

CONCLUSION

Severe hyperglycemia in the first few days after birth is associated with increased odds of death and sepsis in ELBW infants.

Dynamics of Mitochondria and Mitochondrial Ca2+near the Plasma Membrane of PC12 Cells: A Study by Multimode Microscopy

The goal of this study is to examine whether there is a difference in the regulation of Ca2+ between mitochondria near the cell surface and mitochondria in the cytosol. Total internal reflection fluorescence and epifluorescence microscopy were used to monitor changes in the mitochondrial Ca2+ ([Ca2+]mt) between the mitochondria near the plasma membrane and those in the cytosol. The results show that [Ca2+]mt near the plasma membrane increased earlier and decayed slower after high K+ stimulation than average mitochondria in the cytosol. In addition, the changes in [Ca2+]mt in the mitochondria near the cell surface after a second stimulation were larger than those induced by the first stimulation. The results provide direct evidence to support the hypothesis that mitochondria in different subcellular localization show differential responses to the influx of extracellular Ca2+.

An evanescent approach for mitochondrial function assay of living cells

Mitochondria are now known to function physiologically not only in the production of ATP as the major cellular energy source, but also in the regulation of intracellular signaling, in, for example, stress-induced apoptosis and buffering of cytosolic calcium. It should be noted, when interpreting mitochondrial studies in situ, that mitochondria within cells show heterogeneity in both function and location. We applied both conventional epifluorescence microscopy (EPIFM) and total-internal-reflection fluorescence microscopy (TIRFM) in this study. Image data taken from TIRFM are excellent and markedly different from those taken from EPIFM. We further investigated the physiological variations of mitochondrial functions using an EPIFM/TIRFM dual-imaging system. This system permits further analysis of functions of mitochondria and other organelles with more precision than is possible using a traditional platform.

Effects of caffeine on phosphatidylinositide turnover and calcium mobilization in human neuroblastoma SK-N-SH cells

The effects of caffeine on receptor-controlled Ca2+ mobilization and turnover of inositol phosphates in human neuroblastoma SK-N-SH cells were studied. Caffeine inhibited both the rise in cytosolic Ca2+ concentration ([Ca2+]i) evoked by muscarinic receptor agonists and the total production of inositol phosphates in a dose-dependent manner, but to different extents. At 10 mM, caffeine inhibited agonist-evoked generation of inositol phosphates almost completely, whereas the agonist-evoked [Ca2+]i rise remained observable after caffeine treatment, in the absence or presence of extracellular Ca2+. Raising the cytosolic cAMP concentration increased the carbachol-induced [Ca2+]i rise, and this effect was abolished in the presence of caffeine. Our data suggested that caffeine may exert two effects on receptor-controlled Ca2+ mobilization: 1) inhibition of inositol phosphate production, 2) augmentation of the size of the releasable Ca2+ pool by elevating cytosolic cAMP concentration.

Synergistic effects of dopamine and Zn2+ on the induction of PC12 cell death and dopamine depletion in the striatum: possible implication in the pathogenesis of Parkinson's disease

The mechanism that underlies the progressive degeneration of the dopaminergic neurons in Parkinson's disease (PD) is not clear. The Zn(2+) level in the substantia nigra of Parkinson's patients is increased. However, it is unknown whether Zn(2+) has a role in the degeneration of dopaminergic neurons. This study identifies an interaction between dopamine and Zn(2+) that induces cell death. When PC12 cells were pretreated with Zn(2+) before dopamine treatment, dopamine and Zn(2+) synergistically increased cell death, while Zn(2+) and H(2)O(2) had only additive effects on cell death. The synergistic effect appeared to be caused by increased apoptosis rather than necrosis. The synergistic effect was specific for Zn(2+). The synergistic effect was inhibited by thiol antioxidants but was not significantly affected by calcium channel blockers. There is a similar synergistic effect when dopamine and Zn(2+) were coinfused into the striatum, resulting in striatal dopamine content depletion in vivo. Thus, both dopamine oxidation and Zn(2+) are possibly linked to the degeneration of dopaminergic neurons.

In vitro differentiation of size-sieved stem cells into electrically active neural cells

Size-sieved stem (SS) cells isolated from human bone marrow and propagated in vitro are a population of cells with consistent marker typing, and can form bone, fat, and cartilage. In this experiment, we demonstrated that SS cells could be induced to differentiate into neural cells under experimental cell culture conditions. Five hours after exposure to antioxidant agents (beta-mercaptoethanol +/- retinoic acid) in serum-free conditions, SS cells expressed the protein for nestin, neuron-specific enolase (NSE), neuron-specific nuclear protein (NeuN), and neuron-specific tubulin-1 (TuJ-1), and the mRNA for NSE and Tau. Immunofluorescence showed that almost all the cells (>98%) expressed NeuN and TuJ-1. After 5 days of beta-mercaptoethanol treatment, the SS cells expressed neurofilament high protein but not mitogen-activated protein-2, glial filament acidic protein, and galactocerebroside. For such long-term-treated cells, voltage-sensitive ionic current could be detected by electrophysiological recording, and the intracellular calcium ion, Ca(2+), concentration can be elevated by high potassium (K(+)) buffer and glutamate. These findings suggest that SS cells may be an alternative source of undifferentiated cells for cell therapy and gene therapy in neural dysfunction.

Amphetamine enhances Ca2+ entry and catecholamine release via nicotinic receptor activation in bovine adrenal chromaffin cells

Amphetamine, a psychostimulant, has been shown to act as a channel blocker of muscle nicotinic receptors and to induce a Ca(2+)-dependent secretion from adrenal chromaffin cells. In this study, the relationship between amphetamine and nicotinic receptors was studied using bovine adrenal chromaffin cells as a model system. Our results show that D-amphetamine sulfate alone induced an increase in the cytosolic Ca(2+) concentration ([Ca(2+)](c)) and [3H]norepinephrine release in a dose-dependent and extracellular Ca(2+)-dependent manner. Two common nicotinic receptor antagonists, hexamethonium and mecamylamine, suppressed the D-amphetamine sulfate-induced [Ca(2+)](c) rise and [3H]norepinephrine release. In addition, D-amphetamine sulfate inhibited the 1,1-dimethyl-4-phenyl-piperazinium iodide (DMPP)-induced [Ca(2+)](c) rise and [3H]norepinephrine release, but not the high K(+)- or veratridine-induced [Ca(2+)](c) increase and [3H]norepinephrine release. Antagonists, including alpha-bungarotoxin and choline, that are more specific for alpha7 nicotinic receptors were capable of inhibiting the D-amphetamine sulfate-induced [Ca(2+)](c) rise, while D-amphetamine sulfate was found to be capable of inhibiting the [Ca(2+)](c) rise induced by the alpha7-nicotinic receptor agonists, epibatidine and choline. Moreover, D-amphetamine sulfate dose-dependently suppressed [3H]nicotine binding to chromaffin cells. We, therefore, conclude that D-amphetamine sulfate acts as a nicotinic receptor agonist to induce [Ca(2+)](c) increase and [3H]norepinephrine release in bovine adrenal chromaffin cells.

Butyl benzyl phthalate blocks Ca2+ signaling and catecholamine secretion coupled with nicotinic acetylcholine receptors in bovine adrenal chromaffin cells

Butyl benzyl phthalate (BBP), a plasticizer and an environmental pollutant, exerts genomic estrogenic-like effects via estrogen receptors. In addition to exerting genomic effects via intracellular steroid receptors, estrogen exerts non-genomic effects through interactions with membrane ion channels to lead the rapid alteration of neuronal excitability. Estradiol is known as to have modulating role on nicotinic acetylcholine receptors (nAChR). We investigated the possibility of BBP exerting non-genomic estrogenic-like effects on nAChR in bovine adrenal chromaffin cells. Our results show that BBP inhibited Ca2+ signaling induced by the nicotinic ligands carbachol, 1,1-dimethyl-4-phenyl-piperazinium iodide (DMPP) and epibatidine (IC50 levels of 4.3, 4.1, 5.4 microM, respectively) as well as high K+ solution (IC50 50.9 microM). Additionally, in the electrophysiological observations, BBP blocked the inward current coupled with nAChR under the stimulation of carbachol. We, therefore, suggest that nAChR and voltage-gated Ca2+ channels are major and minor sites, respectively, of BBP action on the plasma membrane. The inhibitory effect of BBP on nAChR was found to be both noncompetitive and reversible, remaining unchanged as nAChR ligand concentration increased and decreased after washing. BBP was 10 times more potent than estradiol in inhibiting nAChR-coupled Ca2+ signals. We conclude that BBP exerts a novel rapidly inhibitory effect on nAChR.

Nitric oxide reduces blood pressure in the nucleus tractus solitarius: a real time electrochemical study

Increasing evidence has demonstrated that nitric oxide (NO) is involved in central cardiovascular regulation. In this study, we directly measured extracellular NO levels, in real-time, in the nucleus tractus solitarius (NTS) of anesthetized cats using Nafion/Porphyrine/o-Phenylenediamine-coated NO sensors. We found that local application of L-arginine (L-Arg) induced NO overflow in NTS and hypotension. These responses were potentiated in the vagotomized animals. Pretreatment with NO synthase (NOS)/guanylate cyclase inhibitor methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one or NO scavenger hemoglobin attenuated L-Arg-induced hypotension, suggesting that exogenous supplement of NO suppressed cardiac functions through the NOS/cyclic guanosine monophosphate mechanism. The role of endogenous NO was examined after local application of N(G)-nitro-L-arginine methyl ester (L-NAME). We found that L-NAME suppressed endogenous NO levels in NTS and elicited hypertension and tachycardia. Taken together, our data suggest that NO is tonically released in the NTS to inhibit blood pressure.

Binding of actin to chromaffin granules and mitochondrial fractions of adrenal medulla

Binding of actin to chromaffin granules was confirmed and shown to be salt dependent and eliminated by prior trypsin treatment of the granules. However, purified granules bind less actin than do crude granules. A mitochondria-enriched fraction was found to bind substantially more actin per mg protein than did the secretory vesicle fraction. Binding of actin by the secretory vesicles therefore is not a good indication that actin plays an active role in exocytosis.

A technique for laparoscopic-assisted percutaneous drainage of infected pancreatic necrosis and pancreatic abscess

BACKGROUND

Percutaneous drainage has been shown to be an acceptable method for treating both pancreatic abscesses and infected pancreatic necrosis. However, percutaneous techniques have certain shortcomings, including the time and labor required and failure of the catheters to adequately drain the particulate debris. Growing experience around the world indicates that there is a role for retroperitoneal laparoscopy as a means of facilitating the percutaneous drainage of infected pancreatic fluid collections and avoiding a laparotomy. Our technique is discussed in this paper.

METHODS

Once infection is documented in a pancreatic fluid collection by fine-needle aspiration, one or more percutaneous drains are placed into the fluid collection(s). A computed tomography (CT) scan is repeated. If further drainage is indicated, retroperitoneoscopic debridement is performed. Using a combination of the percutaneous drain(s) and the post-drain CT scan, ports are placed and retroperitoneoscopic debridement of the necrosectum is performed under direct visualization. Prior to completion of the operation, a postoperative lavage system is created.

RESULTS

Six patients with infected pancreatic necrosis have been treated with this technique. Prior to commencement of our laparoscopic protocol, all six patients would have required open necrosectomy. Four of the six patients were managed with retroperitoneoscopic debridement and catheter drainage alone. Complications included a colocutaneous fistula and a small flank hernia. There were no bleeding complications and no deaths.

CONCLUSION

Although open necrosectomy remains the standard of care for the treatment of infected pancreatic necrosis and pancreatic abscess, there is growing evidence that laparoscopic retroperitoneal debridement is feasible.

Proteomic analysis of proteins in PC12 cells before and after treatment with nerve growth factor: increased levels of a 43-kDa chromogranin B-derived fragment during neuronal differentiation

Proteomic analysis is an important approach to characterizing the proteome and studying protein function in the post-genomic era. It is also a powerful screening method for detecting unexpected alterations in protein expression that may be missed by conventional biochemical techniques. The aim of this study was to perform a preliminary proteomic analysis of PC12 cells in order to investigate the effect of nerve growth factor (NGF) on protein expression in PC12 cells during neurite outgrowth. PC12 cell proteins were separated by two-dimensional electrophoresis (2DE) and visualized by silver staining, then certain proteins were identified by N-terminal amino acid microsequencing and a homology search of a protein sequence database. Over 400 proteins were detected, 10% of which showed a significant (greater than 30%) increase or decrease in expression during NGF-induced neuronal differentiation. Seven proteins in the 2DE map were identified; the levels of five of these were unaffected by NGF treatment, whereas the levels of the other two, beta-tubulin and a novel 43-kDa chromogranin B-derived fragment, were significantly increased by more than 30 and 200%, respectively. Our results suggest that chromogranin B processing is enhanced in PC12 cells during NGF-induced neuronal differentiation. In addition, since this increase in the levels of the chromogranin B-derived fragment was specifically blocked by PD98059, we suggest that the increased processing can be ascribed to activation of the MAP kinase pathway, and that the 43-kDa chromogranin B-derived fragment can serve as a new marker of neuronal differentiation for proteomic studies.