Prehospital capillary lactate in children differentiates epileptic seizure from febrile seizure, syncope, and psychogenic nonepileptic seizure.

PURPOSE: The aim of the study was to examine prehospital capillary lactate in children as a diagnostic biomarker to differentiate epileptic seizures from febrile seizures, syncope, and psychogenic nonepileptic seizures (PNES). METHODS: Capillary lactate concentrations taken in a pediatric prehospital setting within 2 h of the paroxysmal event were compared retrospectively between patients with epileptic seizure, febrile seizure, syncope, and PNES, based on the final diagnosis from the hospitalization report. RESULTS: One hundred and two patients were included, 53 (52%) with epileptic seizures, 41 (40%) with febrile seizures, and 8 (8%) with syncope or PNES. Capillary lactate in patients with a final diagnosis of epileptic seizure was significantly increased in comparison to the concentrations in patients with febrile seizure (p < 0.0007) and in comparison to the concentrations in patients with syncope or PNES (p < 0.0204). The area under the ROC-curve was 0.71 (95% CI 0.61-0.80). For a cutoff concentration of prehospital capillary lactate >3.9 mmol/l (Youden index), the sensitivity was 49% and the specificity 92%. CONCLUSION: Prehospital capillary lactate concentrations are a useful tool for differentiating the nature of a paroxysmal event in children.

In sickness and in health: the role of TRAPP and associated proteins in disease.

Transport protein particle (TRAPP) represents a series of related protein complexes that function in specific stages of inter-organelle traffic. They share a core of subunits that can activate the GTPase Rab1 through a guanine nucleotide exchange factor (GEF) activity and are distinguished by 'accessory' subunits giving each complex its distinct function. The subunits are ubiquitously expressed and, thus, mutations in TRAPP subunits would be expected to be embryonic lethal. However, since its discovery, a number of subunits have been found to be mutated in several diverse human disorders suggesting that some of these subunits may have cell- or tissue-specific functions. Here we review the current state of knowledge with respect to TRAPP subunit mutations in human disease. We suggest ideas to explain their tissue-specific phenotypes and present avenues for future investigation.

Are all multisubunit tethering complexes bona fide tethers?

Since the late 1990s, a number of multisubunit tethering complexes (MTCs) have been described that function in membrane trafficking events: TRAPP I, TRAPP II, TRAPP III, COG, HOPS, CORVET, Dsl1, GARP and exocyst. On the basis of structural and sequence similarities, they have been categorized as complexes associated with tethering containing helical rods (CATCHR) (Dsl1, COG, GARP and exocyst) or non-CATCHR (TRAPP I, II and III, HOPS and CORVET) complexes (Yu IM, Hughson FM. Tethering factors as organizers of intracellular vesicular traffic. Annu Rev Cell Dev Biol 2010;26:137-156). Both acronyms (CATCHR and MTC) imply these complexes tether opposing membranes to facilitate fusion. The main question we will address is: have these complexes been formally demonstrated to function as tethers? If the answer is no, then is it premature or even correct to refer to them as tethers? In this commentary, we will argue that the vast majority of MTCs have not been demonstrated to act as a tether. We propose that a distinction between the terms tether and tethering factor be considered to address this issue.

A trs20 mutation that mimics an SEDT-causing mutation blocks selective and non-selective autophagy: a model for TRAPP III organization.

TRAPP is a multisubunit complex that functions in membrane traffic. Mutations in the mammalian TRAPP protein C2 are linked to the skeletal disorder spondyloepiphyseal dysplasia tarda (SEDT) that is thought to arise from an inability to secrete procollagen from the endoplasmic reticulum. Here, we show that C2 binds to the SNARE protein Syntaxin 5 and this interaction is weakened by an SEDT-causing missense mutation (D47Y). Interestingly, the equivalent mutation (D46Y) in the yeast C2 homolog Trs20p does not block anterograde traffic but did affect endocytosis. The trs20D46Y mutation interfered with the interaction between Trs20p and Trs85p (TRAPP III-specific subunit), Trs120p and Trs130p (TRAPP II-specific subunits). Size exclusion chromatography suggested that this yeast mutation destabilized the TRAPP III complex that is involved in autophagy. We further show that this mutation blocks both the selective cytosol-to-vacuole (cvt) pathway as well as non-selective autophagy. We demonstrate that the apparent molecular size of the TRAPP III complex is dependent upon membranes, and that the presence of TRAPP III is dependent upon Atg9p. Finally, we demonstrate that lipidated Bet3p is enriched in TRAPP III and that lipidation increases the efficiency of autophagy. Our study suggests that Trs20p acts as an adaptor for Trs85p and Trs120p and reveals complexities in TRAPP III assembly and function. The implications of C2D47Y in SEDT are discussed.

A pure familial 6q15q21 split duplication associated with obesity and transmitted with partial reduction.

Familial transmission of chromosome 6 duplications is rare. We report on the first observation of a maternally-inherited pure segmental 6q duplication split into two segments, 6q15q16.3 and 6q16.3q21, and associated with obesity. Obesity has previously been correlated to chromosome 6 q-arm deletion but has not yet been assessed in duplications. The aim of this study was to characterize the structure of these intrachromosomal insertional translocations by classic cytogenetic banding, array-CGH, FISH, M-banding and genotyping using microsatellites and SNP array analysis, in a mother and four offspring. The duplicated 6q segments, 9.75 Mb (dup 1) and 7.05 Mb (dup 2) in size in the mother, were inserted distally into two distinct chromosome 6q regions. They were transmitted to four offspring. A son and a daughter inherited the two unbalanced insertions and displayed, like the mother, an abnormal phenotype with facial dysmorphism, intellectual disability, and morbid obesity. Curiously, two daughters with a normal phenotype inherited only the smaller segment, 6q16.3q21. The abnormal phenotype was associated with the larger proximal 6q15q16.3 duplication. We hypothesize a mechanism for this exceptional phenomenon of recurrent reduction and transmission of the duplication during meiosis in a family. We expect the interpretation of our findings to be useful for genetic counseling and for understanding the mechanisms underlying these large segmental 6q duplications and their evolution.

TRAPPC2L is a novel, highly conserved TRAPP-interacting protein.

Mutations in the trafficking protein particle complex C2 protein (TRAPPC2), a mammalian ortholog of yeast Trs20p and a component of the trafficking protein particle (TRAPP) vesicle tethering complex, have been linked to the skeletal disorder spondyloepiphyseal dysplasia tarda (SEDT). Intriguingly, the X-linked TRAPPC2 is just one of a complement of Trs20-related genes in humans. Here we characterize TRAPPC2L, a novel, highly conserved TRAPP-interacting protein related to TRAPPC2 and the uncharacterized yeast open reading frame YEL048c. TRAPPC2L and TRAPPC2 genes are found in pairs across species and show broad and overlapping expression, suggesting they are functionally distinct, a notion supported by yeast complementation studies and biochemical characterization. RNA interference-mediated knockdown of either TRAPPC2L or TRAPPC2 in HeLa cells leads to fragmentation of the Golgi, implicating both proteins in Golgi dynamics. Gradient fractionation of cellular membranes indicates that TRAPPC2L is found with a portion of cellular TRAPP on very low-density membranes whereas the remainder of TRAPP, but not TRAPPC2L, is found associated with Golgi markers. YEL048c displays genetic interactions with TRAPP II-encoding genes and the gene product co-fractionates with and interacts with yeast TRAPP II. Taken together these results indicate that TRAPPC2L and its yeast ortholog YEL048c are novel TRAPP-interacting proteins that may modulate the function of the TRAPP II complex.

A comparison of physical activity-related social-cognitive factors between those with type 1 diabetes, type 2 diabetes and diabetes free adults.

Despite strong evidence supporting the benefits of physical activity in managing and preventing diabetes, the majority of Canadians living with or without diabetes are insufficiently active to achieve health benefits. The purpose of this study was to examine the difference in key physical activity-related, psychosocial constructs from major social-cognitive theories/models for individuals with type 1 diabetes (n = 695), type 2 diabetes (n = 1540) and those without diabetes (n = 829). The relatively similar scores reported for the social-cognitive constructs between the groups suggest that theoretically driven, generic population-based strategies operationalizing key socio-cognitive constructs for promoting physical activity may have utility for the general and diabetes specific populations. However, both diabetes groups reported significantly lower (p < 0.001) response efficacy (benefits of physical activity) scores, and higher scores for cons of performing physical activity than the non-diabetes group (p < 0.001). Further, the type 1 diabetes group had significantly higher (p < 0.05) physical activity cons scores than the other two study groups. The findings of this study may guide practitioners in designing population-based, physical activity programs that capitalize on generic strategies for the general and diabetes populations, and identify efforts as to where specific tailoring (e.g. emphasizing physical activity benefits) is needed for those living with diabetes.

The efficacy of stage-matched and standard public health materials for promoting physical activity in the workplace: the Physical Activity Workplace Study (PAWS).

PURPOSE: To compare the effects of stage-matched and standard print materials for physical activity (PA) change. DESIGN: Participants were randomized into (1) a stage-matched intervention group (n = 165), (2) a standard intervention group (n = 176), or (3) a no-contact control group (n = 166). The stage-matched and standard intervention groups both received materials at baseline, 3 months, and 6 months. Assessments of all three groups were conducted at baseline, 6, and 12 months. SETTING: Canadian worksites. SUBJECTS: Employees (N = 507). INTERVENTIONS: Five motivationally targeted booklets were developed for the stage-matched group. The standard group received Canada's Physical Activity Guide and handbook. MEASURES: The main dependent variable was PA, expressed as metabolic equivalent (MET) minutes and measured using the Godin Leisure-Time Exercise Questionnaire. Demographic characteristics and stages of change for PA were also assessed. RESULTS: At 12 months mean weekly MET minutes for combined moderate and vigorous activity increased from baseline by 223, 67, and 78 for the stage-matched, standard, and control groups, respectively; however, differences were not significant (p > .05). Women in the stage-matched group over the 12-month period significantly increased their activity by 327 weekly MET minutes whereas the standard and control groups declined their activity (F = 3.01, p < .05). CONCLUSION: PA stage-matched materials delivered in the workplace are efficacious for women but not men. Future interventions should explore the use of these intervention materials in conjunction with multilevel strategies, and particular attention should be paid to possible gender differences.

The TRAPP Subunit Trs130p Interacts with the GAP Gyp6p to Mediate Ypt6p Dynamics at the Late Golgi.

Small GTPases of the Rab superfamily participate in virtually all vesicle-mediated trafficking events. Cycling between an active GTP-bound form and an inactive GDP-bound form is accomplished in conjunction with guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), respectively. Rab cascades have been described in which an effector of an activated Rab is a GEF for a downstream Rab, thus ensuring activation of a pathway in an ordered fashion. Much less is known concerning crosstalk between GEFs and GAPs although regulation between these factors could also contribute to the overall physiology of a cell. Here we demonstrate that a subunit of the TRAPP II multisubunit tethering factor, a Rab GEF, participates in the recruitment of Gyp6p, a GAP for the GTPase Ypt6p, to Golgi membranes. The extreme carboxy-terminal portion of the TRAPP II subunit Trs130p is required for the interaction between TRAPP II and Gyp6p. We further demonstrate that TRAPP II mutants, but not a TRAPP III mutant, display a defect in Gyp6p interaction. A consequence of this defective interaction is the enhanced localization of Ypt6p at late Golgi membranes. Although a ypt31/32 mutant also resulted in an enhanced localization of Gyp6p at the late Golgi, the effect was not as dramatic as that seen for TRAPP II mutants, nor was Ypt31/32 detected in the same TRAPP II purification that detected Gyp6p. We propose that the interaction between TRAPP II and Gyp6p represents a parallel mechanism in addition to that mediated by Ypt31/32 for the recruitment of a GAP to the appropriate membrane, and is a novel example of crosstalk between a Rab GAP and GEF.

Physical activity of Aboriginals with type 2 diabetes: an exploratory study.

Given the magnitude of the diabetes epidemic among Canadian Aboriginals and the corresponding need to develop physical activity interventions, the aims of this study were to: 1) examine the meaning of physical activity; 2) assess physical activity behavior levels; and 3) examine the association of key Social Cognitive Theory (SCT) constructs with physical activity behavior. Thirty-four Aboriginals with diabetes completed a survey composed of questions regarding: 1) the perceived meaning of physical activity; 2) physical activity behavior; and 3) SCT constructs. An emerging theme revealed that some participants perceived physical activity leisure-time activities as appropriate across the lifespan, while the majority perceived leisure-time activities to be only for youth. Based on the reported energy expenditure estimates, 61.5% of participants were categorized as sedentary. However, when occupational and household activities were taken into account, 33.0% were categorized as sedentary. Bivariate correlations revealed that no SCT constructs were significantly associated with energy expenditure scores. Results suggest that specific SCT construct items may help understand physical activity behavior change.

The SMS domain of Trs23p is responsible for the in vitro appearance of the TRAPP I complex in Saccharomyces cerevisiae.

Saccharomyces cerevisiae transport protein particle (TRAPP) is a family of related multisubunit complexes required for endoplasmic reticulum-to-Golgi transport (TRAPP I), endosome-to-Golgi transport (TRAPP II) or cytosol to vacuole targeting (TRAPP III). To gain insight into the relationship between these complexes, we generated random and targeted mutations in the Trs23p core subunit. Remarkably, at physiological salt concentrations only two peaks (TRAPP I and a high molecular weight peak) are detected in wild-type cells. As the salt was raised, the high molecular weight peak resolved into TRAPP II and III peaks. Deletion of a Saccharomycotina-specific domain of Trs23p resulted in destabilization of TRAPP I but had no effect on TRAPP II or III. This mutation had no observable growth phenotype, normal levels of Ypt1p-directed guanine nucleotide exchange factor activity in vivo and did not display any in vivo nor in vitro blocks in membrane traffic. Biochemical analysis indicated that TRAPP I could be produced from the TRAPP II/III peak in vitro by increasing the salt concentration. Our data suggest that the SMS domain of Trs23p is responsible for the in vitro appearance of TRAPP I in S. cerevisiae. The implications of these findings are discussed.

C4orf41 and TTC-15 are mammalian TRAPP components with a role at an early stage in ER-to-Golgi trafficking.

TRAPP is a multisubunit tethering complex implicated in multiple vesicle trafficking steps in Saccharomyces cerevisiae and conserved throughout eukarya, including humans. Here we confirm the role of TRAPPC2L as a stable component of mammalian TRAPP and report the identification of four novel components of the complex: C4orf41, TTC-15, KIAA1012, and Bet3L. Two of the components, KIAA1012 and Bet3L, are mammalian homologues of Trs85p and Bet3p, respectively. The remaining two novel TRAPP components, C4orf41 and TTC-15, have no homologues in S. cerevisiae. With this work, human homologues of all the S. cerevisiae TRAPP proteins, with the exception of the Saccharomycotina-specific subunit Trs65p, have now been reported. Through a multidisciplinary approach, we demonstrate that the novel proteins are bona fide components of human TRAPP and implicate C4orf41 and TTC-15 (which we call TRAPPC11 and TRAPPC12, respectively) in ER-to-Golgi trafficking at a very early stage. We further present a binary interaction map for all known mammalian TRAPP components and evidence that TRAPP oligomerizes. Our data are consistent with the absence of a TRAPP I-equivalent complex in mammalian cells, suggesting that the fundamental unit of mammalian TRAPP is distinct from that characterized in S. cerevisiae.