Loss of Nuclear Envelope Integrity and Increased Oxidant Production Cause DNA Damage in Adult Hearts Deficient in PKP2: A Molecular Substrate of ARVC

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by high propensity to life-threatening arrhythmias and progressive loss of heart muscle. More than 40% of reported genetic variants linked to ARVC reside in the PKP2 gene, which encodes the PKP2 protein (plakophilin-2).

METHODS

We describe a comprehensive characterization of the ARVC molecular landscape as determined by high-resolution mass spectrometry, RNA sequencing, and transmission electron microscopy of right ventricular biopsy samples obtained from patients with ARVC with PKP2 mutations and left ventricular ejection fraction >45%. Samples from healthy relatives served as controls. The observations led to experimental work using multiple imaging and biochemical techniques in mice with a cardiac-specific deletion of Pkp2 studied at a time of preserved left ventricular ejection fraction and in human induced pluripotent stem cell-derived PKP2-deficient myocytes.

RESULTS

Samples from patients with ARVC present a loss of nuclear envelope integrity, molecular signatures indicative of increased DNA damage, and a deficit in transcripts coding for proteins in the electron transport chain. Mice with a cardiac-specific deletion of Pkp2 also present a loss of nuclear envelope integrity, which leads to DNA damage and subsequent excess oxidant production (O2.- and H2O2), the latter increased further under mechanical stress (isoproterenol or exercise). Increased oxidant production and DNA damage is recapitulated in human induced pluripotent stem cell-derived PKP2-deficient myocytes. Furthermore, PKP2-deficient cells release H2O2 into the extracellular environment, causing DNA damage and increased oxidant production in neighboring myocytes in a paracrine manner. Treatment with honokiol increases SIRT3 (mitochondrial nicotinamide adenine dinucleotide-dependent protein deacetylase sirtuin-3) activity, reduces oxidant levels and DNA damage in vitro and in vivo, reduces collagen abundance in the right ventricular free wall, and has a protective effect on right ventricular function.

CONCLUSIONS

Loss of nuclear envelope integrity and subsequent DNA damage is a key substrate in the molecular pathology of ARVC. We show transcriptional downregulation of proteins of the electron transcript chain as an early event in the molecular pathophysiology of the disease (before loss of left ventricular ejection fraction <45%), which associates with increased oxidant production (O2.- and H2O2). We propose therapies that limit oxidant formation as a possible intervention to restrict DNA damage in ARVC.

Abstract P2083: Erk-mediated Phosphorylation Of Grk2 Leads To Reduced Pyruvate Dehydrogenase Activity And Alters Pyroptotic Signaling

G protein-coupled receptors (GPCRs) are important regulators of cellular functions where agonist binding leads to receptor conformational changes and downstream activation of g-protein-mediated signaling cascades. Signal transduction is terminated by receptor phosphorylation mediated by G-protein coupled receptor kinases (GRKs). GPCR kinase 2 (GRK2) is a main GRK in the heart and is upregulated in heart failure (HF) patients. Recently, we and others have shown that GRK2 can translocate to cardiac mitochondria where it regulates metabolism. Notably, we found that phosphorylated GRK2 at S670 post- ischemia/reperfusion (IR) decreases glucose mitochondrial utilization and pyruvate dehydrogenase (PDH) activity. Furthermore, 2D-SDS PAGE followed by LC/MS/MS revealed a potential link between mitochondrial GRK2 and PDH phosphorylation. Using a novel PDHα KI CRISPR Cas HEK cell line, we tested the hypothesize that PDH phosphorylation of this novel site was important for PDH activity. Utilizing cytosolic and mitochondrially-targeted pyruvate indicators we measured pyruvate levels in WT and KI HEK cells. In parallel, using a novel mouse model GRK2-S670A, we investigated the role of ERK in mediating GRK2 mitochondrial translocation and pyroptotic signaling. Further experiments will determine long-term impact of mitochondrial GRK2 in cell survival in cardiac pathological conditions.

Double life: How GRK2 and β-arrestin signaling participate in diseases

G-protein coupled receptor (GPCR) kinases (GRKs) and β-arrestins play key roles in GPCR and non-GPCR cellular responses. In fact, GRKs and arrestins are involved in a plethora of pathways vital for physiological maintenance of inter- and intracellular communication. Here we review decades of research literature spanning from the discovery, identification of key structural elements, and findings supporting the diverse roles of these proteins in GPCR-mediated pathways. We then describe how GRK2 and β-arrestins partake in non-GPCR signaling and briefly summarize their involvement in various pathologies. We conclude by presenting gaps in knowledge and our prospective on the promising pharmacological potential in targeting these proteins and/or downstream signaling. Future research is warranted and paramount for untangling these novel and promising roles for GRK2 and arrestins in metabolism and disease progression.

Myocardial GRK2 Reduces Fatty Acid Metabolism and β-Adrenergic Receptor-Mediated Mitochondrial Responses

G-protein coupled receptor (GPCR) kinase 2 (GRK2) is upregulated in heart failure (HF) patients and mouse models of cardiac disease. GRK2 is a regulator of β-adrenergic receptors (βARs), a GPCR involved in ionotropic and chronotropic responses. We and others have recently reported GRK2 to be localized in the mitochondria, although its function in the mitochondria and/or metabolism remain not clearly defined. We hypothesized that upregulation of GRK2 reduced mitochondrial respiratory function and responses to βAR activation. Utilizing isolated mouse primary adult cardiomyocytes (ACMs), we investigated the role of glucose, palmitate, ketone bodies, and BCAAs in mediating cell survival. Our results showed that myocyte upregulation of GRK2 promotes palmitate-induced cell death. Isotopologue labeling and mass spectrometry showed that the upregulation of GRK2 reduces β-hydroxybutyryl CoA generation. Next, using isoproterenol (ISO), a non-selective βAR-agonist, we determined mitochondrial function in mouse and human primary ACMs. Upregulation of GRK2 impaired ISO-mediated mitochondrial functional responses, which we propose is important for metabolic adaptations in pathological conditions. Increased cardiac levels of GRK2 reduced fatty acid-specific catabolic pathways and impaired ISO-stimulated mitochondrial function. Our data support the notion that GRK2 participates in bioenergetic remodeling and may be an important avenue for the development of novel pharmacological strategies in HF.

Changes in Myocardial Metabolism Preceding Sudden Cardiac Death

Heart disease is widely recognized as a major cause of death worldwide and is the leading cause of mortality in the United States. Centuries of research have focused on defining mechanistic alterations that drive cardiac pathogenesis, yet sudden cardiac death (SCD) remains a common unpredictable event that claims lives in every age group. The heart supplies blood to all tissues while maintaining a constant electrical and hormonal feedback communication with other parts of the body. As such, recent research has focused on understanding how myocardial electrical and structural properties are altered by cardiac metabolism and the various signaling pathways associated with it. The importance of cardiac metabolism in maintaining myocardial function, or lack thereof, is exemplified by shifts in cardiac substrate preference during normal development and various pathological conditions. For instance, a shift from fatty acid (FA) oxidation to oxygen-sparing glycolytic energy production has been reported in many types of cardiac pathologies. Compounded by an uncoupling of glycolysis and glucose oxidation this leads to accumulation of undesirable levels of intermediate metabolites. The resulting accumulation of intermediary metabolites impacts cardiac mitochondrial function and dysregulates metabolic pathways through several mechanisms, which will be reviewed here. Importantly, reversal of metabolic maladaptation has been shown to elicit positive therapeutic effects, limiting cardiac remodeling and at least partially restoring contractile efficiency. Therein, the underlying metabolic adaptations in an array of pathological conditions as well as recently discovered downstream effects of various substrate utilization provide guidance for future therapeutic targeting. Here, we will review recent data on alterations in substrate utilization in the healthy and diseased heart, metabolic pathways governing cardiac pathogenesis, mitochondrial function in the diseased myocardium, and potential metabolism-based therapeutic interventions in disease.

Screening Isolates of Soybean mosaic virus for Infectivity in a Model Plant, Nicotiana benthamiana

Soybean mosaic virus (SMV), belonging to the genus Potyvirus of the family Potyviridae, has a relatively narrow host range almost exclusively confined to leguminous hosts. While disease management through genetic transformation can be an effective approach, soybean remains recalcitrant to routine genetic transformation. In this context, it is important to identify new hosts for SMV that can be used to develop effective transgenic resistance strategies. Transformation in Nicotiana benthamiana is simple and highly efficient; hence, here we demonstrate the infectivity of SMV strain SC7 in N. benthamiana plants. To identify an SMV strain infectious in N. benthamiana, we mechanically inoculated N. benthamiana plants with 37 isolates from 21 (SC1 to SC21) SMV strains. Plants inoculated with isolates of strain SC7 produced mosaic symptoms on leaves. However, N. benthamiana plants inoculated with the 20 other SMV strains showed no visible symptoms. Furthermore, soybean cv. Nannong 1138-2 inoculated with sap prepared from symptomatic N. benthamiana leaves showed typical SMV mosaic symptoms 2 weeks after inoculation. In addition, SMV was detected in symptomatic N. benthamiana and soybean leaves by RT-PCR, DAS-ELISA, and further identified by sequencing. Together, the results indicate that N. benthamiana plants could support multiplication of SMV strain SC7. The findings of this study would be useful for the investigation of SMV resistance using the model plant N. benthamiana.

Serum bilirubin levels on ICU admission are associated with ARDS development and mortality in sepsis

BACKGROUND

Hyperbilirubinaemia is a common complication of sepsis. Elevated bilirubin may induce inflammation and apoptosis. It was hypothesised that increased serum bilirubin on Intensive Care Unit (ICU) admission contributes to sepsis-related acute respiratory distress syndrome (ARDS).

METHODS

Serum bilirubin on ICU admission was measured in 1006 patients with sepsis. Serial serum bilirubin was analysed prospectively in patients with sepsis who had ARDS for a period of 28 days. The effects of clinical factors and variants of the UGT1A1 gene on serum bilirubin levels were determined. Outcomes were ARDS risk and mortality.

RESULTS

During 60-day follow-up, 326 patients with sepsis developed ARDS, of whom 144 died from ARDS. The hyperbilirubinaemia (>or=2.0 mg/dl) rate in patients with ARDS (22.4%) was higher than in those without ARDS (14.1%, p = 0.002). For each 1.0 mg/dl increase in admission bilirubin, ARDS risk and 28- and 60-day ARDS mortalities were increased by 7% (OR = 1.07; p = 0.003), 20% (OR = 1.20; p = 0.002) and 18% (OR = 1.18; p = 0.004), respectively. Compared with subjects with bilirubin levels <2.0 mg/dl, patients with hyperbilirubinaemia had higher risks of ARDS (OR = 2.12; p = 0.0007) and 28-day (OR = 2.24; p = 0.020) and 60-day ARDS mortalities (OR = 2.09; p = 0.020). In sepsis-related ARDS, serial bilirubin levels in non-survivors were consistently higher than in survivors (p<0.0001). Clinical variables explained 29.5% of the interindividual variation in bilirubin levels, whereas genetic variants of UGT1A1 contributed 7.5%.

CONCLUSION

In sepsis, a higher serum bilirubin level on ICU admission is associated with subsequent ARDS development and mortality.

Epidermal growth factor (EGF) gene polymorphism, gastroesophageal reflux disease (GERD), and esophageal adenocarcinoma (EAC) risk

11029

Background: Single nucleotide polymorphisms (SNPs) of key cancer genes, such as EGF A61G, are associated with an elevated risk of EAC, but the lack of full penetrance indicates that the effects of these SNPs on esophageal carcinogenesis are modified by additional genetic or environmental variables. Since GERD is an established risk factor for EAC, we evaluated whether the association between EGF polymorphism and EAC development is altered by the presence of GERD. Methods: EGF genotyping of DNA samples was performed and GERD history was collected for 309 EAC patients and 275 matched healthy controls. Associations between genotypes and EAC risk were examined with adjusted logistic regression. Genotype-GERD relationships were explored using analyses stratified by GERD history and joint effects models that considered severity and duration of GERD symptoms. Results: Baseline characteristics were comparable between cases and controls except that EGF variants (A/G or G/G) were more common (p=0.02) and GERD was more prevalent (p<0.001) in cases than in controls. When compared to the EGF wild type A/A genotype, the G/G variant was associated with an increased risk of EAC (OR 1.9; 95% CI, 1.2–3.0; p=0.007). Stratified analyses revealed that the G/G variant contributed to a substantial increase in EAC risk among individuals with GERD, but a slight decrease in risk for GERD-free individuals (see table). In the joint effects models, the odds of EAC was also highest for G/G patients who either experienced frequent GERD of more than once per week (OR 21.8; 95% CI, 5.1–94.0; p<0.001) or suffered GERD for longer than 15 years (OR 22.4; 95% CI, 6.5–77.6; p<0.001). There was a highly significant interaction between the G/G genotype and the presence of GERD (p<0.001). Conclusions: EGF A61G polymorphism exerts its effect on EAC susceptibility through an interaction with GERD. Performing EGF genotyping for patients with severe or longstanding GERD can help to identify individuals at the greatest risk of EAC. [Table: see text]

No significant financial relationships to disclose.

Sex-specific association of epidermal growth factor gene polymorphisms with acute respiratory distress syndrome

Epidermal growth factor (EGF) is involved in alveolar epithelial repair, lung fluid clearance and inflammation, and is regulated by sex hormones. An unmatched, nested case-control study was conducted to evaluate the associations of EGF variants with acute respiratory distress syndrome (ARDS) and the role of sex on the associations between EGF variants and ARDS. Patients with ARDS risk factors upon intensive care unit admission were enrolled. Cases were 416 Caucasians who developed ARDS and controls were 1,052 Caucasians who did not develop ARDS. Cases were followed for clinical outcomes and 60-day mortality. One functional single nucleotide polymorphism (SNP), rs4444903, and six haplotype-tagging SNPs spanning the entire EGF gene were genotyped. No individual SNP or haplotype was associated with ARDS risk or outcomes in all subjects. Sex-stratified analyses showed opposite effects of EGF variants on ARDS in males versus in females. SNPs rs4444903, rs2298991, rs7692976 and rs4698803, and haplotypes GGCGTC and ATCAAG were associated with ARDS risk in males. No associations were observed in females. Interaction analysis showed that rs4444903, rs2298991, rs7692976 and rs6533485 significantly interacted with sex for ARDS risk. The present study suggests that associations of epidermal growth factor gene variants with acute respiratory distress syndrome risk are modified by sex. The current findings should be replicated in other populations.

Polymorphisms of inflammatory and metalloproteinase genes, Helicobacter pylori infection and the risk of oesophageal adenocarcinoma

Helicobacter pylori (HP) infection appears protective against oesophageal adenocarcinoma (EA) risk. Matrix metalloproteinases (MMPs) are released in the presence of HP infection. In MMP2 wild-type individuals, HP was significantly protective of EA risk (adjusted odds ratio: 0.29; 95% confidence interval=0.1-0.7). Matrix metalloproteinases may modulate the EA-HP relationship.

Matrix metalloproteinase 2 (MMP2) polymorphism, Helicobacter pylori (HP) infection and esophageal adenocarcinoma (EA) risk

10553

Background: Epidemiologic studies suggest that HP infection protects against EA risk, as HP-mediated chronic atrophic gastritis reduces acid reflux. Genetic variations may modify the host response to HP infection and alter this risk. MMP2 expression is commonly upregulated in HP infections. We hypothesize that a functional MMP2 promoter polymorphism (-C1306T) that abolishes a Sp1 binding site and decreases promoter activity will also reduce the protective effects of HP infections in EA risk. Methods: HP status was determined in 98 EA patients and 101 age and gender matched healthy controls, using a commercially available serum immunoblotting kit (Helicoblot 2.1, Genelabs Diagnostics) that measures ever, current, CagA+ and VacA+ HP infections. Genotyping was performed using TaqMan. Data were analyzed using unconditional logistic regression. Results: 39% of cases and 44% of controls (P=0.69) had MMP2 variants (T/T or C/T). 36% of cases and 42% of controls were ever HP infected (P= 0.35). In individuals carrying the MMP2 wild type (CC) genotype, ever HP infection was strongly protective against EA [Odds Ratio (OR) 0.32: 95% CI, 0.13–0.75; P=0.008]. In contrast, in individuals carrying the MMP2 variants that are associated with lower promoter activity, this protective effect was lost (OR 1.76; 95% CI, 0.06–5.2; P= 0.30). Similar results were found when evaluating the MMP2 and current, CagA or VacA infection. Statistical interactions between MMP2 genotype and ever HP infection (P=0.027) and between MMP2 genotype and VacA+ infection (P= 0.035) were significant. Conclusions: We are the first to report that host factors such as the MMP2 polymorphism modulate the role of HP infection in EA susceptibility.

No significant financial relationships to disclose.

MMP1 1G/2G promoter polymorphism and risk of esophageal adenocarcinoma

10555

Background: The 2G allele of the MMP1 -1607 1G/2G promoter polymorphism creates an Ets binding site that leads to increased transcriptional and enzyme activity, particularly in the presence of growth factors and cytokines. This polymorphism has been associated with greater risk of cancer (e.g., renal cell, lung and oral cancers, glioblastomas) and cancer invasiveness (e.g., melanoma, cervical, lung and colorectal cancer). The aim of the current study was to evaluate the role of this MMP 1G/2G polymorphism in the risk of esophageal adenocarcinoma (EA). Methods: We evaluated 323 histologically confirmed EA cases and 464 healthy controls frequency-matched for age and gender. Genotyping of the MMP1 1G/2G promoter polymorphism involved a Taqman approach. All EAs had endoscopic evidence showing that the center of the tumors were located at or above the gastroesophageal junction. Odds Ratios (OR) were calculated using multivariate logistic regression, adjusted for age, gender, smoking status, and body-mass index (BMI) at the age of 18 years (to represent a healthy adult BMI). Results: Genotype frequencies were: 33% (1G/1G), 47% (1G/2G) & 20% (2G/2G) in controls; in cases, 26% (1G/1G), 50% (1G/2G) & 24% (2G/2G). 88% of cases were male. The MMP1 2G/2G and 1G/2G genotypes conferred a greater risk of EA, with adjusted ORs of 1.50 (95%CI=1.0–2.3) and 1.34 (95%CI=0.9–1.9), respectively, when compared with the wildtype 1G/1G genotype. The 2G allele (2G/2G + 1G/2G) conferred an adjusted OR of 1.38 (95%CI=1.0–1.9). By stage, the adjusted ORs for the 2G allele were 1.26 (95%CI=0.8–2.1), 1.45 (95%CI=0.9–2.3), & 1.54 (95%CI=0.9–2.7) for node negative, node-positive, and metastatic disease, respectively. Conclusions: The 2G allele of the MMP1 -1607 1G/2G polymorphism was associated with an increased risk of EA in this analysis. In addition, there was a non-significant trend towards conferring greater risk in the more advanced stages of EA, suggesting a possible role of this polymorphism in the invasiveness of this cancer.

No significant financial relationships to disclose.

Genotypes and haplotypes of the VEGF gene are associated with higher mortality and lower VEGF plasma levels in patients with ARDS

BACKGROUND

Endothelial injury is an important prognostic factor in acute respiratory distress syndrome (ARDS). Vascular endothelial growth factor (VEGF) plays a critical role in endothelial destruction and angiogenesis. Genetic variations of the VEGF gene have been associated with VEGF production. A study was undertaken to investigate the impact of VEGF gene polymorphisms on the clinical outcomes of ARDS.

METHODS

Three VEGF polymorphisms (-460C/T, +405C/G and +936C/T) were determined in 1253 patients in an intensive care unit with risk factors for ARDS, 394 of whom developed ARDS. Patients were followed for assessment of 60 day survival. Plasma VEGF levels were measured in 71 patients with ARDS.

RESULTS

The +936TT (OR 4.29, 95% CI 1.12 to 16.40, p = 0.03) and +936CT+TT (OR 1.98, 95% CI 1.14 to 3.42, p = 0.01) genotypes were significantly associated with increased mortality from ARDS. Plasma VEGF levels in patients with ARDS with the +936CT+TT genotype were significantly lower than in subjects with the +936CC genotype (median 49 (IQR 16-98) pg/ml vs 112 (IQR 47-162) pg/ml, p = 0.02). At the haplotype level, haplotype TCT (-460T+405C+936T) was significantly associated with a higher rate of mortality (OR 2.89, 95% CI 1.30 to 6.43, p = 0.009) and haplotype CGT (-460C+405G+936T) was associated less strongly with increased mortality (OR 1.90, 95% CI 0.94 to 3.83, p = 0.07) in patients with ARDS. Lower plasma VEGF levels were correlated with the probability of haplotype CGT (coefficient = -0.26, p<0.05), but the same trend of correlation was not significant to haplotype TCT.

CONCLUSIONS

VEGF polymorphisms may contribute to the prognosis and inter-individual variations in circulating VEGF levels in patients with ARDS.

Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), and their soluble receptors in coal workers' pneumoconiosis

The aim of this study was to investigate whether systemic tumor necrosis factor alpha (TNF-alpha), soluble TNF-alpha receptors (p55, p75), interleukin 6 (IL-6), and soluble IL-6 receptor could be markers of biological activities of coal workers' pneumoconiosis (CWP). The study population was composed of 182 Chinese retired coal miners who had similar dust exposure histories. Among them, 71 were cases with CWP and 111 were controls. Chest radiographs were classified according to International Labour Organization Criteria (ILO, 1980). Individual dust exposure variables were estimated from work histories, and smoking information was obtained from interviews. Serum concentrations of TNF-alpha, TNF-alpha receptors (p55, p75), IL-6, and IL-6 receptor were measured by ELISA techniques. Mean serum levels of p55, p75 and IL-6 were significantly higher in cases than in controls (P < or = 0.01 for each comparison by crude analyses). Results from logistic regression models, adjusted for age, dust exposure variables, and smoking habits, found similar associations between soluble p55 and p75 levels and the presence of CWP. Linear regression analysis revealed that CWP radiographic stage (by ILO criteria) was significantly correlated with the individual serum concentrations of p55, p75 and IL-6. Serum concentrations of all measured cytokines were notcorrelated to age, dust exposure, or smoking, but there were correlations between soluble p75 and p55 levels, and between p75 and IL-6 levels. The results of this study suggest that serum levels of TNF receptors and IL-6 are associated with the fibrotic process of CWP and serum cytokine levels may be correlated with the severity of CWP.

The G to C polymorphism at -174 of the interleukin-6 gene is rare in a Southern Chinese population

Interleukin-6 is thought to be involved in the pathogenesis of coal workers' pneumoconiosis. Recently, a functional G to C polymorphism at position -174 of the promoter of the IL-6 gene has been described. We examined the -174 polymorphisms in 259 retired Chinese men from Guangxi province (all retired coal miners). Only one GC heterozygous and no CC homozygous variants were found. Our results suggest that the frequency of the C allele in this Chinese population is lower than in Caucasian and east Indian populations.

The dynamics of SAP90/PSD-95 recruitment to new synaptic junctions

SAP90/PSD-95 is thought to be a central organizer of the glutamatergic synapse postsynaptic reception apparatus. To assess its potential role during glutamatergic synapse formation, we used GFP-tagged SAP90/PSD-95, time lapse confocal microscopy, and cultured hippocampal neurons to determine its dynamic recruitment into new synaptic junctions. We report that new SAP90/PSD-95 clusters first appeared at new axodendritic contact sites within 20-60 min of contact establishment. SAP90/PSD-95 clustering was rapid, with kinetics that fit a single exponential with a mean time constant of approximately 23 min. Most new SAP90/PSD-95 clusters were found juxtaposed to functional presynaptic boutons as determined by labeling with FM 4-64. No evidence was found for the existence of discrete transport particles similar to those previously reported to mediate presynaptic active zone cytoskeleton assembly. Instead, we found that SAP90/PSD-95 is recruited to nascent synapses from a diffuse dendritic cytoplasmic pool. Our findings show that SAP90/PSD-95 is recruited to nascent synaptic junctions early during the assembly process and indicate that its assimilation is fundamentally different from that of presynaptic active zone components.

Temporal appearance of the presynaptic cytomatrix protein bassoon during synaptogenesis

Bassoon is a 420-kDa presynaptic cytomatrix protein potentially involved in the structural organization of neurotransmitter release sites. In this study, we have investigated a possible role for Bassoon in synaptogenesis and in defining synaptic vesicle recycling sites. We find that it is expressed at early stages of neuronal differentiation in which it is selectively sorted into axons. As synaptogenesis begins, Bassoon clusters appear along dendritic profiles simultaneously with synaptotagmin I, sites of synaptic vesicle recycling, and the acquisition of functional excitatory and inhibitory synapses. A role for Bassoon in the assembly of excitatory and inhibitory synapses is supported by the colocalization of Bassoon clusters with clusters of GKAP and AMPA receptors as well as GABA(A) receptors. These data indicate that the recruitment of Bassoon is an early step in the formation of synaptic junctions.

[The causes of death in patients with malignant biliary obstruction treated by metallic stent and/or biliary drainage]

OBJECTIVE

To analyze the causes of death in patients with malignant bile duct obstruction treated by metallic stent endoprosthesis and biliary drainage.

METHODS

One hundred and seven patients with malignant bile duct obstruction were so treated. Of the 107 patients, 12 (11.2%) died within 30 days after operation. The bile duct obstruction in the 12 cases was due to primary hepatic cancer(n = 4), metastasis of lymph nodes in hepatic hilus(n = 3) and bile duct cancer(n = 5).

RESULTS

Five patients died of biliary infections, 4 patients died of hepatic coma, and 2 patients died of cancerous cachexia and 1 patient died of biliary tract hemorrhage.

CONCLUSION

The major causes of postoperative death of patients with biliary obstruction treated by metallic stent to support bile duct are biliary infection and hepatic encephalopathy.

Piccolo, a presynaptic zinc finger protein structurally related to bassoon

Piccolo is a novel component of the presynaptic cytoskeletal matrix (PCM) assembled at the active zone of neurotransmitter release. Analysis of its primary structure reveals that Piccolo is a multidomain zinc finger protein structurally related to Bassoon, another PCM protein. Both proteins were found to be shared components of glutamatergic and GABAergic CNS synapses but not of the cholinergic neuromuscular junction. The Piccolo zinc fingers were found to interact with the dual prenylated rab3A and VAMP2/Synaptobrevin II receptor PRA1. We show that PRA1 is a synaptic vesicle-associated protein that is colocalized with Piccolo in nerve terminals of hippocampal primary neurons. These data suggest that Piccolo plays a role in the trafficking of synaptic vesicles (SVs) at the active zone.

Presynaptic cytomatrix protein bassoon is localized at both excitatory and inhibitory synapses of rat brain

Bassoon is a 420-kDa protein specifically localized at the active zone of presynaptic nerve terminals. It is thought to be involved in the structural organization of the neurotransmitter release site. We studied the distribution of Bassoon transcripts and protein in rat brain and assessed which types of presynaptic terminals contain the protein. As shown by in situ hybridization, Bassoon transcripts are widely distributed in the brain and occur primarily in excitatory neurons. In addition, examples of gamma-aminobutyric acid (GABA)-ergic neurons expressing Bassoon are detected. At the light microscopic level, Bassoon immunoreactivity is found in synaptic neuropil regions throughout the brain, with the strongest expression in the hippocampus, the cerebellar cortex, and the olfactory bulb. Immunoelectron microscopy showed that Bassoon immunoreactivity is found in both asymmetric type 1 and symmetric type 2 synapses. Immunopositive asymmetric synapses include mossy fiber boutons and various spine and shaft synapses in the hippocampus and mossy fiber terminals and parallel fiber terminals in the cerebellum. Bassoon-containing symmetric synapses are observed, e.g., between basket and granule cells in the hippocampus, between Golgi cells and granule cells, and between basket cells and Purkinje cells in the cerebellum. Within synaptic terminals, Bassoon appears highly concentrated at sites opposite to postsynaptic densities. In cultured hippocampal neurons, Bassoon was found to colocalize with GABA(A) and glutamate (GluR1) receptors. These data indicate that Bassoon is a component of the presynaptic apparatus of both excitatory glutamatergic and inhibitory GABAergic synapses.

Polymorphisms in the promoter of the tumor necrosis factor-alpha gene in coal miners

Tumor necrosis factor-alpha (TNF) is recognized as a central mediator of mineral dust-induced lung fibrosis, and genetic polymorphisms of the TNF promoter have been reported to influence levels of TNF production. To assess whether polymorphisms within the TNF promoter gene are associated with susceptibility to coal workers' pneumoconiosis (CWP), the DNA of 78 coal miners was typed for G-to-A transitions at positions -238 and -308. Our results show that frequency of A-308 genotype (T2) is significantly overpresented in coal miners with CWP (50%), as compared with miners without CWP (25%) and controls (29%). After correction for cumulative dust exposure and smoking, the A-308 transition genotype is still associated with the presence of CWP (OR = 3.0, 95% CI = 1.0-9.0). Both A-238 and A-308 transition genotypes were related to TNF release from endotoxin-stimulated blood monocytes; only the A-238 transition and not the A-308 transition was associated to coal dust-induced TNF release. In summary, this study shows that the A-308 transition is related to CWP, but this relation is not paralleled by a different TNF release in this genotype. A larger number of patients coupled to frequent TNF release are required to evaluate genotype screening to estimate individual health risks for effects of coal mine dust exposure.

Microglia and astroglia have a common progenitor cell

Disaggregated neopallial cells from newborn C3H/HeJ mice were cloned in Grenier hybridoma tissue culture dishes, and culture wells that contained only one cell were marked. After 8-10 days of culturing, the cultures were fixed and double immunolabeled for microglia with Mac-1 antibody and for astroglia with antibody to GFAP. Each marked well containing a clone was identified as either a microglia, astroglia, mixed microglia-astroglia, or an unlabeled clone. The effect of LM cell line conditioned medium (LM-CM), which contains colony-stimulating factor-1, on the development of mixed microglia-astroglia clones was determined. Formation of mixed clones was dose dependent (P < 0.0001). We concluded that microglia and astroglia have a common progenitor cell and that the development of mixed clones is LM-CM dependent.

Production of anti-peptide antibody of rat brain nitric-oxide synthase

AIM

To raise antibody of rat brain nitric-oxide synthase (bNOS) through immunizing animal with a peptide of bNOS that can represent the holoprotein.

METHODS

The amino acid sequence for the bNOS was analyzed by GenePro computer program. According to the hydrophilicity, hydrophobicity, antigenicity, and the potentiality to form protein second structures of alpha-helix, beta-sheet and beta-turn, the structure of bNOS was predicted. The peptide 277-287 was selected that was predicted to be in the antigen epitope of bNOS. The peptide was chemically synthesized, coupled to keyhole limphet hemocyanin carrier protein and injected into rabbits to raise antibody. The specificity of the antibody was tested by enzyme-linked immunosorbent assay, immunohistochemistry, and Western blotting.

RESULTS

The antibody bound the protein in rat cerebellum extract. In Western blotting, the antibody bound the protein band of 150 kDa in SDS-PAGE, and the binding was inhibited by peptide conjugated with carrier protein. In immunohistochemistry, the stain was collocated with the stain in NADPH-dehydrogenase histochemistry.

CONCLUSION

The antibody against the peptide recognized the natural bNOS in rat brain, and the peptide 277-287 was located on the surface of bNOS.

[Quality, value and risks of pelvic/ leg angiography before PTA (percutaneous transluminal angioplasty)]

This study evaluates the diagnostic value and image quality of 183 angiographies performed prior to angioplasty. 56% of the examinations were by arterial and 42% by intravenous DSA. Both techniques were underestimating mild and overestimating severe stenoses. With arterial DSA, 42% of the images in the iliac, 63% in the femoropopliteal, and 53% in the crural region showed an excellent quality. With venous DSA, these percentages were 31%, 47%, and 8%, respectively. Newly occurring occlusions were observed in the iliac region in 8%, and in the femoropopliteal region in 14% of the patients. Venous DSA and other, alternative techniques are sufficient in stage II of POVD and after surgery. In stages III and IV, as well as in diabetic patients and prior to femoro-crural bypasses, an arterial DSA has to be performed. In appropriate lesions, the interval of time to the intervention should be as short as possible to avoid progression of arterial thrombosis.

Primitive fossil rodent from Inner Mongolia and its implications for mammalian phylogeny

The evolutionary origin of rodents is obscured by the group's sudden and highly transformed first appearance in the fossil record in the latest Paleocene. We report here the discovery of nearly complete dental remains of an extraordinary new primitive rodent from strata of transitional Paleocene-Eocene age in Inner Mongolia, China. The strikingly conservative morphological features of this taxon, Tribosphenomys minutus, gen. et sp. nov., substantially modify previous ideas about the ancestral rodent morphotype, which in turn has important implications for understanding the origin of rodents and their relationship to other eutherian mammals. This new fossil, in conjunction with recent morphological and molecular evidence confirming rodent monophyly, indicates the need for a reassessment of phylogenetic affinities among gliriform eutherians. Our results indicate a sister-group position of the new taxon to other rodents, and support the alliance of lagomorphs (rabbits) and rodents (cohort Glires). They also suggest that paraphyly of an extinct assemblage, the 'Eurymylidae', and reveal an unexpectedly complex pattern of character evolution near the ancestry of Rodentia.