The Golgi complex of dopaminergic enteric neurons is fragmented in a hemiparkinsonian rat model.

Since gastrointestinal disorders are early consequences of Parkinson's disease (PD), this disease is clearly not restricted to the central nervous system (CNS), but also significantly affects the enteric nervous system (ENS). Large aggregates of the protein α-synuclein forming Lewy bodies, the prototypical cytopathological marker of this disease, have been observed in enteric nervous plexuses. However, their value in early prognosis is controversial. The Golgi complex (GC) of nigral neurons appears fragmented in Parkinson's disease, a characteristic common in most neurodegenerative diseases. In addition, the distribution and levels of regulatory proteins such as Rabs and SNAREs are altered, suggesting that PD is a membrane traffic-related pathology. Whether the GC of enteric dopaminergic neurons is affected by the disease has not yet been analyzed. In the present study, dopaminergic neurons in colon nervous plexuses behave as nigral neurons in a hemiparkinsonian rat model based on the injection of the toxin 6-OHDA. Their GCs are fragmented, and some regulatory proteins' distribution and expression levels are altered. The putative mechanisms of the transmission of the neurotoxin to the ENS are discussed. Our results support the possibility that GC structure and the level of some proteins, especially syntaxin 5, could be helpful as early indicators of the disease. RESEARCH HIGHLIGHTS: The Golgi complexes of enteric dopaminergic neurons appear fragmented in a Parkinson's disease rat model. Our results support the hypothesis that the Golgi complex structure and levels of Rab1 and syntaxin 5 could be helpful as early indicators of the disease.

Focus on the Small GTPase Rab1: A Key Player in the Pathogenesis of Parkinson's Disease.

Parkinson's disease (PD) is the second most frequent neurodegenerative disease. It is characterized by the loss of dopaminergic neurons in the substantia nigra and the formation of large aggregates in the survival neurons called Lewy bodies, which mainly contain α-synuclein (α-syn). The cause of cell death is not known but could be due to mitochondrial dysfunction, protein homeostasis failure, and alterations in the secretory/endolysosomal/autophagic pathways. Survival nigral neurons overexpress the small GTPase Rab1. This protein is considered a housekeeping Rab that is necessary to support the secretory pathway, the maintenance of the Golgi complex structure, and the regulation of macroautophagy from yeast to humans. It is also involved in signaling, carcinogenesis, and infection for some pathogens. It has been shown that it is directly linked to the pathogenesis of PD and other neurodegenerative diseases. It has a protective effect against α-σψν toxicity and has recently been shown to be a substrate of LRRK2, which is the most common cause of familial PD and the risk of sporadic disease. In this review, we analyze the key aspects of Rab1 function in dopamine neurons and its implications in PD neurodegeneration/restauration. The results of the current and former research support the notion that this GTPase is a good candidate for therapeutic strategies.

Fragmentation of the Golgi complex of dopaminergic neurons in human substantia nigra: New cytopathological findings in Parkinson's disease.

Fragmentation of the Golgi ribbon is a common feature of Parkinson´s disease and other neurodegenerative diseases. This alteration could be the consequence of the anterograde and retrograde transport imbalance, α-synuclein aggregates, and/or cytoskeleton alterations. Most information on this process has been obtained from cellular and animal experimental models, and as such, there is little information available on human tissue. If the information on human tissue was available, it may help to understand the cytopathological mechanisms of this disease. In the present study, we analyzed the morphological characteristics of the Golgi complex of dopaminergic neurons in human samples of substantia nigra of control and Parkinson's disease patients. We measured the expression levels of putative molecules involved in Golgi fragmentation, including α-synuclein, tubulin, and Golgi-associated regulatory and structural proteins. We show that, as a consequence of the disease, the Golgi complex is fragmented into small stacks without vesiculation. We found that only a limited number of regulatory proteins are altered. Rab1, a small GTPase regulating endoplasmic reticulum-to-Golgi transport, is the most dramatically affected, being highly overexpressed in the surviving neurons. We found that the SNARE protein syntaxin 5 forms extracellular aggregates resembling the amyloid plaques characteristic of Alzheimer's disease. These findings may help to understand the cytopathology of Parkinson's disease.

Golgi Fragmentation in Neurodegenerative Diseases: Is There a Common Cause?

In most mammalian cells, the Golgi complex forms a continuous ribbon. In neurodegenerative diseases, the Golgi ribbon of a specific group of neurons is typically broken into isolated elements, a very early event which happens before clinical and other pathological symptoms become evident. It is not known whether this phenomenon is caused by mechanisms associated with cell death or if, conversely, it triggers apoptosis. When the phenomenon was studied in diseases such as Parkinson's and Alzheimer's or amyotrophic lateral sclerosis, it was attributed to a variety of causes, including the presence of cytoplasmatic protein aggregates, malfunctioning of intracellular traffic and/or alterations in the cytoskeleton. In the present review, we summarize the current findings related to these and other neurodegenerative diseases and try to search for clues on putative common causes.

A new insight into the three-dimensional architecture of the Golgi complex: Characterization of unusual structures in epididymal principal cells.

Principal epididymal cells have one of the largest and more developed Golgi complex of mammalian cells. In the present study, we have used this cell as model for the study of the three-dimensional architecture of the Golgi complex of highly secretory and endocytic cells. Electron tomography demonstrated the presence in this cell type of some unknown or very unusual Golgi structures such as branched cisternae, pocket-like cisternal invaginations or tubular connections. In addition, we have used this methodology and immunoelectron microscopy to analyze the close relationship between this organelle and both the endoplasmic reticulum and microtubules, and to describe in detail how these elements interact with compact and non-compact regions of the ribbon.

Outcomes of peptic ulcer bleeding following treatment with proton pump inhibitors in routine clinical practice: 935 patients with high- or low-risk stigmata.

OBJECTIVE: To assess rates of further bleeding, surgery and mortality in patients hospitalized owing to peptic ulcer bleeding. MATERIALS AND METHODS: Consecutive patients hospitalized for peptic ulcer bleeding and treated with a proton pump inhibitor (PPI) (esomeprazole or pantoprazole) were identified retrospectively in 12 centers in Spain. Patients were included if they had high-risk stigmata (Forrest class Ia-IIb, underwent therapeutic endoscopy and received intravenous PPI ≥120 mg/day for ≥24 h) or low-risk stigmata (Forrest class IIc-III, underwent no therapeutic endoscopy and received intravenous or oral PPI [any dose]). RESULTS: Of 935 identified patients, 58.3% had high-risk stigmata and 41.7% had low-risk stigmata. After endoscopy, 88.3% of high-risk patients and 22.1% of low-risk patients received intravenous PPI therapy at doses of at least 160 mg/day. Further bleeding within 72 h occurred in 9.4% and 2.1% of high- and low-risk patients, respectively (p < 0.001). Surgery to stop bleeding was required within 30 days in 3.5% and 0.8% of high- and low-risk patients, respectively (p = 0.007). Mortality at 30 days was similar in both groups (3.3% in high-risk and 2.3% in low-risk patients). CONCLUSION: Among patients hospitalized owing to peptic ulcer bleeding and treated with PPIs, patients with high-risk stigmata have a higher risk of further bleeding and surgery, but not of death, than those with low-risk stigmata.

Golgi tubules: their structure, formation and role in intra-Golgi transport.

Tubules are common Golgi elements that can form extensive networks associated with the cis-, lateral and trans-Golgi sides, but despite this, they have almost been forgotten for decades. The molecular mechanisms involved in their formation, elongation and fission are only just beginning to be understood. However, the role of these membranes is not well understood. In the present review, we analyze the mechanisms that induce Golgi tubulation or, conversely, disrupt tubules in order to throw some lights on the nature of these elements. The putative role of these elements in the framework of current models for intra-Golgi transport is also discussed.

Morpho-functional architecture of the Golgi complex of neuroendocrine cells.

In neuroendocrine cells, prohormones move from the endoplasmic reticulum to the Golgi complex (GC), where they are sorted and packed into secretory granules. The GC is considered the central station of the secretory pathway of proteins and lipids en route to their final destination. In most mammalian cells, it is formed by several stacks of cisternae connected by tubules, forming a continuous ribbon. This organelle shows an extraordinary structural and functional complexity, which is exacerbated by the fact that its architecture is cell type specific and also tuned by the functional status of the cell. It is, indeed, one the most beautiful cellular organelles and, for that reason, perhaps the most extensively photographed by electron microscopists. In recent decades, an exhaustive dissection of the molecular machinery involved in membrane traffic and other Golgi functions has been carried out. Concomitantly, detailed morphological studies have been performed, including 3D analysis by electron tomography, and the precise location of key proteins has been identified by immunoelectron microscopy. Despite all this effort, some basic aspects of Golgi functioning remain unsolved. For instance, the mode of intra-Golgi transport is not known, and two opposing theories (vesicular transport and cisternal maturation models) have polarized the field for many years. Neither of these theories explains all the experimental data so that new theories and combinations thereof have recently been proposed. Moreover, the specific role of the small vesicles and tubules which surround the stacks needs to be clarified. In this review, we summarize our current knowledge of the Golgi architecture in relation with its function and the mechanisms of intra-Golgi transport. Within the same framework, the characteristics of the GC of neuroendocrine cells are analyzed.

Effect of proton pump inhibitors on the outcomes of peptic ulcer bleeding: comparison of event rates in routine clinical practice and a clinical trial.

OBJECTIVE: To assess clinical outcomes in patients treated with proton pump inhibitors (PPIs) after endoscopic hemostasis in routine clinical care, and to compare these outcomes to those seen in a randomized controlled trial (RCT) of i.v. esomeprazole. MATERIALS AND METHODS: Patients with peptic ulcer bleeding and endoscopic stigmata of recent hemorrhage, who were treated with i.v. esomeprazole or pantoprazole ≥120 mg/day following therapeutic endoscopy, were identified from 12 hospitals in Spain (n = 539). Outcomes assessed included further bleeding, all-cause mortality and surgery. The results were compared to those of the RCT. RESULTS: Overall, 9.1% (95% confidence interval [CI]: 6.7-11.5) of patients experienced further bleeding within 72 h following initial endoscopy, 14.3% (95% CI: 11.3-17.2) of patients had further bleeding within 30 days and 3.3% (95% CI: 1.8-4.9) of patients died within 30 days. In the RCT, the rate of rebleeding within 72 h was significantly lower in the esomeprazole arm (5.9%) than in the placebo arm (10.3%; p = 0.026). The further bleeding rate in patients treated with esomeprazole in routine clinical practice (7.8%; 95% CI: 4.6-11.1) was between these two values. Similar results were seen with the other outcomes studied. CONCLUSIONS: The proportion of patients treated with i.v. esomeprazole in routine clinical practice who experienced further bleeding following endoscopic treatment for peptic ulcer bleeding was between the rates observed in the esomeprazole group and the placebo group in the RCT.

Golgi fragmentation is Rab and SNARE dependent in cellular models of Parkinson's disease.

Fragmentation of the Golgi ribbon is a common feature of many neurodegenerative diseases but little is known about the causes of this alteration. In Parkinson's disease, it is believed to be the consequence of an ER-Golgi transport imbalance and/or of cytoskeleton alterations. In the present study, we analyze the mechanisms involved in Golgi fragmentation in differentiated PC12 cells treated with 6-hydroxydopamine or methamphetamine as cellular models of Parkinson's disease. Our data demonstrate that Golgi fragmentation precedes and might trigger the aggregation of α-synuclein and the formation of inclusions, alterations in anterograde and retrograde transport between the endoplasmic reticulum and Golgi complex, and cytoskeleton damage. In contrast, fragmentation is directly related with alterations in the levels of Rab1, 2 and 8 and the SNARE protein syntaxin 5. Thus, overexpression of Rab1 and 8 and depletion of Rab2 and syntaxin 5 rescue the Golgi morphology. In conclusion, the homeostasis of a limited number of Rab and SNARE proteins is important for understanding the cytopathology of Parkinson's disease.

Alcohol induces Golgi fragmentation in differentiated PC12 cells by deregulating Rab1-dependent ER-to-Golgi transport.

In the present study, we analyze the effects of ethanol on the Golgi structure and membrane transport in differentiated PC12 cells, which are used as a model of neurons. Chronic exposure to moderate doses of ethanol induces Golgi fragmentation, a common characteristic of many neurodegenerative diseases. Alcohol impaired the lateral linking of stacks without causing microtubule damage. Extensive immunocytochemical and western blot analyses of representative Golgi proteins showed that few, but important, proteins are significantly affected. Thus, alcohol exposure induced a significant ER-to-Golgi transport delay, the retention of the GTPase Rab1 in the Golgi membranes and the accumulation of tethering factor p115 in the cytosol. These modifications would explain the observed fragmentation. The amount of p115 and the stacking protein GRASP65 increased in alcohol-treated cells, which might be a mechanism to reverse Golgi damage. Importantly, the overexpression of GTP-tagged Rab1 but not of a dominant-negative Rab1 mutant, restored the Golgi morphology, suggesting that this protein is the main target of alcohol. Taken together, our results support the view that alcohol and neurodegenerative diseases such as Parkinson have similar effects on intracellular trafficking and provide new clues on the neuropathology of alcoholism.

Lower GI bleeding is more common than upper among patients on dual antiplatelet therapy: long-term follow-up of a cohort of patients commonly using PPI co-therapy.

OBJECTIVE: Patients undergoing percutaneous coronary intervention require dual antiplatelet therapy. Proton-pump inhibitor (PPI) therapy is recommended for the prevention of upper GI complications. No study has determined the rate and type of GI bleeding events in such patients in routine clinical practice. DESIGN: Observational study with a prospective follow-up to confirm medication use and occurrence of events, which were validated. PATIENTS AND SETTING: We have followed up a cohort of 1219 consecutive patients admitted for percutaneous coronary intervention in Zaragoza (Spain). MAIN OUTCOME MEASURES: Major GI bleeding and cardiovascular events. RESULTS: At discharge, 96.7% of patients were on dual antiplatelet therapy and 76.6% on PPI therapy, which increased up to 87.9% during follow-up of 2107.6 patient (pt) s-years (1.72±1.07 years/patient). There were eight patients who developed GI bleeding during hospitalisation and 27 patients during follow-up, (1.52 bleeds per 100 pt-years). Most GI bleeding events (81.4%) occurred during the first year (mean time to bleeding event: 7.03±7.65 months) and 84.6% of patients were on long-term PPI at the time of the bleed. Lower GI bleeding occurred more frequently than upper GI bleeding (74% lower vs. 26% upper). Peptic ulcer history and concomitant warfarin therapy were the only risk factors identified for upper or lower GI bleeding respectively. CONCLUSIONS: Among patients on dual antiplatelet therapy and PPI co-therapy, gastrointestinal bleeding episodes are more frequent in the lower GI tract. This changing pattern of bleeding may reflect the success of gastroprotection and focuses attention on research to address lower GI bleeding in this population.

Colonoscopy versus fecal immunochemical testing in colorectal-cancer screening.

BACKGROUND: Colonoscopy and fecal immunochemical testing (FIT) are accepted strategies for colorectal-cancer screening in the average-risk population. METHODS: In this randomized, controlled trial involving asymptomatic adults 50 to 69 years of age, we compared one-time colonoscopy in 26,703 subjects with FIT every 2 years in 26,599 subjects. The primary outcome was the rate of death from colorectal cancer at 10 years. This interim report describes rates of participation, diagnostic findings, and occurrence of major complications at completion of the baseline screening. Study outcomes were analyzed in both intention-to-screen and as-screened populations. RESULTS: The rate of participation was higher in the FIT group than in the colonoscopy group (34.2% vs. 24.6%, P<0.001). Colorectal cancer was found in 30 subjects (0.1%) in the colonoscopy group and 33 subjects (0.1%) in the FIT group (odds ratio, 0.99; 95% confidence interval [CI], 0.61 to 1.64; P=0.99). Advanced adenomas were detected in 514 subjects (1.9%) in the colonoscopy group and 231 subjects (0.9%) in the FIT group (odds ratio, 2.30; 95% CI, 1.97 to 2.69; P<0.001), and nonadvanced adenomas were detected in 1109 subjects (4.2%) in the colonoscopy group and 119 subjects (0.4%) in the FIT group (odds ratio, 9.80; 95% CI, 8.10 to 11.85; P<0.001). CONCLUSIONS: Subjects in the FIT group were more likely to participate in screening than were those in the colonoscopy group. On the baseline screening examination, the numbers of subjects in whom colorectal cancer was detected were similar in the two study groups, but more adenomas were identified in the colonoscopy group. (Funded by Instituto de Salud Carlos III and others; ClinicalTrials.gov number, NCT00906997.).

Prescription of and adherence to non-steroidal anti-inflammatory drugs and gastroprotective agents in at-risk gastrointestinal patients.

OBJECTIVES: Patients with gastrointestinal (GI) risk factors who take non-steroidal anti-inflammatory drugs (NSAIDs) should also take gastroprotective agents (GPAs). No studies have evaluated adherence and reasons for non-adherence to GPA and NSAID therapies. METHODS: This was a prospective, multicenter, observational, longitudinal study. Patients attending rheumatology/orthopedic clinics who were co-prescribed NSAID plus GPA for at least 15 days and had risk factors for GI complications were followed up by telephone call. Optimal adherence was defined as taking the drug for ≥ 80% of prescribed days. Multivariate logistic regression analysis was used to determine factors associated with non-adherence. RESULTS: Of 1,232 patients interviewed, 192 were excluded because of inaccurate data. Of the remaining 1,040 patients, 74 % were prescribed low-dose NSAIDs and 99.8 % were prescribed a standard or high-dose GPA. In all, 70 % of NSAIDs and 63.1 % of GPA prescriptions were short term (< 30 days). The majority of patients who were prescribed either an NSAID (92.5 % ) or GPA (85.9 % ) started therapy. Optimal adherence to GPA or NSAIDs was reported by 79.7 % (95 % confidence interval (CI): 76.9-82.2 % ) and 84.1 % (95 % CI: 81.7-86.3 % ) of patients, respectively. More adverse events occurred among patients who reported non-optimal adherence than among patients with optimal adherence to GPA (22.1 vs. 1.9 % , P < 0.0001). As reasons for non-adherence, patients most frequently cited infrequent/low-intensity rheumatic pain (NSAIDs) or forgetfulness (GPAs). Adverse events and short-term treatment were independent factors associated with poor adherence for both NSAIDs and GPAs. History of uncomplicated peptic ulcer and frequent dosing were additional factors associated with non-adherence to NSAIDs. CONCLUSIONS: Most frequent reasons for non-adherence are infrequent/low-intensity rheumatic pain (NSAIDs) or forgetfulness (GPAs). Short-term treatment and adverse events were associated with poor adherence for both therapies.

Relationship between level of education and breastfeeding duration depends on social context: breastfeeding trends over a 40-year period in Spain.

This article presents trends of breastfeeding in Spain from the 1960s to the end of the century, analyzing the relationship between level of education and breastfeeding duration. A sample of 666 adult women provided data about breastfeeding practices for children born between 1958 and 2002. Joinpoint regression models for breastfeeding duration for the firstborn child throughout these years show a U-shaped curve, with a sharp decrease at the beginning of the 1970s (-17.2%) and a gradual increase toward the end of the century (1.9%). However, the trend for women with primary studies shows a constant decrease throughout the whole period (-7.4%), while higher education levels relate to a positive trend from the 1970s onward (3.4%). The authors conclude that in the Spanish context, maternal level of education is not associated with breastfeeding duration in the same direction or with the same magnitude across time. Factors related to breastfeeding should be studied, taking into account social context.

Regulation of ER-Golgi intermediate compartment tubulation and mobility by COPI coats, motor proteins and microtubules.

Little is known about the formation and regulation of endoplasmic reticulum (ER)-Golgi transport intermediates, although previous studies suggest that cargo is the main regulator of their morphology. In this study, we analyze the role of coat protein I (COPI) and cytoskeleton in the formation of tubular ER-Golgi intermediate compartment (ERGIC) and also show that partial COPI detachment by means of low temperature (15 degrees C) or brefeldin A induces the formation of transient tubular ERGIC elements. Most of them moved from the cell periphery to the perinuclear area and were 2.5x slower than vesicles. Time-lapse analysis of living cells demonstrates that the ERGIC elements are able to shift very fast from tubular to vesicular forms and vice versa, suggesting that the amount of cargo is not the determining factor for ERGIC morphology. Both the partial microtubule depolymerization and the inhibition of uncoating of the membranes result in the formation of long tubules that grow from round ERGICs and form at complex network. Interestingly, both COPI detachment and microtubule depolymerization induce a redistribution of kinesin from peripheral ERGIC elements to the Golgi area, while dynein distribution is not affected. However, both kinesin and dynein downregulation by RNA interference induced ERGIC tubulation. The tubules induced by kinesin depletion were static, whereas those resulting from dynein depletion were highly mobile. Our results strongly suggest that the interaction of motor proteins with COPI-coated membranes and microtubules is a key regulator of ERGIC morphology and mobility.

Time trends and impact of upper and lower gastrointestinal bleeding and perforation in clinical practice.

OBJECTIVES: Changing patterns in medical practice may contribute to temporal changes in the incidence of upper and lower gastrointestinal (GI) complications. There are limited data on the incidence of lower GI complications in clinical practice and most studies that have been done have serious methodological limitations to inferring the actual burden of this problem. The aims of this study were to analyze time trends of hospitalizations resulting from GI complications originating both from the upper and lower GI tract in the general population, and to determine the risk factors, severity, and clinical impact of these GI events. METHODS: This was a population-based study of patients hospitalized because of GI complications in 10 general hospitals between 1996 and 2005 in Spain. We report the age- and gender-specific rates, estimate the regression coefficients of the upper and lower GI event trends, and evaluate the severity and associated risk factors. GI hospitalization charts were validated by an independent review of large random samples of unspecific and specific codes distributed among all hospitals and study years. RESULTS: Upper GI complications fell from 87/100,000 persons in 1996 to 47/100,000 persons in 2005, whereas lower GI complications increased from 20/100,000 to 33/100,000. Overall, mortality rates decreased, but the case fatality remained constant over time. Lower GI events had a higher mortality rate (8.8 vs. 5.5%), a longer hospitalization (11.6+/-13.9 vs. 7.9+/-8.8 days), and higher resource utilization than did upper GI events. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) without concomitant proton pump inhibitor was more frequently recorded among upper GI complications than among lower GI complications. When comparing upper GI events with lower GI events, we found that male gender (adjusted odds ratio (OR): 1.94; 95% confidence interval (CI): 1.70-2.21), and recorded NSAID use (OR: 1.92; 95% CI: 1.60-2.30) were associated to a greater extent with upper GI events, whereas older age (OR: 0.83; 95% CI: 0.77-0.89), number of comorbidities (OR: 0.91; 95% CI: 0.86-0.96), and having a diagnosis in recent years (OR: 0.92; 95% CI: 0.90-0.94) were all associated to a greater extent with lower GI events than with upper GI events after adjusting for age, sex, hospitalization, and discharge year. CONCLUSIONS: Over the past decade, there has been a progressive change in the overall picture of GI events leading to hospitalization, with a clear decreasing trend in upper GI events and a significant increase in lower GI events, causing the rates of these two GI complications to converge. Overall, mortality has also decreased, but the in-hospital case fatality of upper or lower GI complication events has remained constant. It will be a challenge to improve future care in this area unless we develop new strategies to reduce the number of events originating in the lower GI tract, as well as reducing their associated mortality.

Chronic ethanol exposure induces alterations in the nucleocytoplasmic transport in growing astrocytes.

Nucleocytoplasmic transport is a crucial process for cell function. We assessed the general effect of chronic alcohol exposure on this transport in growing astrocytes for the first time. Import and export of proteins to the nucleus were examined by pulse-chase experiments using (3)H-methionine, and we showed that ethanol induces a delay in both processes. Furthermore, we took an approach to evaluate the mechanisms involved in this effect. Whereas alcohol did not affect the amount and the distribution of several representative proteins that participate in nuclear import, such as RanBP1, RanGAP1 and the importins alpha2 and beta3, it decreased the amount of Exp1/CRM1, which is a general export receptor involved in the nuclear export. In addition, the density and distribution of nuclear pore complexes, which contribute to nucleocytoplasmic transport, were also affected by ethanol. These effects can be related with changes found in the content of several proteins associated with the nuclear envelope and the nuclear pore complex structure such as lamins A/C, and nucleoporins p62 and RanBP2, respectively. These results suggest that ethanol could interfere with some of the important processes regulated by nucleocytoplasmic transport in astrocytes and support the idea that one of the main ethanol targets is intracellular transport.

A replicated molecular genetic basis for subtyping antisocial behavior in children with attention-deficit/hyperactivity disorder.

CONTEXT: Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous neurodevelopmental disorder that in some cases is accompanied by antisocial behavior. OBJECTIVE: To test if variations in the catechol O-methyltransferase gene (COMT) would prove useful in identifying the subset of children with ADHD who exhibit antisocial behavior. DESIGN: Three independent samples composed of 1 clinical sample of ADHD cases and 2 birth cohort studies. PARTICIPANTS: Participants in the clinical sample were drawn from child psychiatry and child health clinics in England and Wales. The 2 birth cohort studies included 1 sample of 2232 British children born in 1994-1995 and a second sample of 1037 New Zealander children born in 1972-1973. MAIN OUTCOME MEASURES: Diagnosis of ADHD and measures of antisocial behavior. RESULTS: We present replicated evidence that the COMT valine/methionine polymorphism at codon 158 (COMT Val158Met) was associated with phenotypic variation among children with ADHD. Across the 3 samples, valine/valine homozygotes had more symptoms of conduct disorder, were more aggressive, and were more likely to be convicted of criminal offenses compared with methionine carriers. CONCLUSIONS: The findings confirm the presence of genetic heterogeneity in ADHD and illustrate how genetic information may provide biological evidence pointing to clinical subtypes.

Low temperature (15 degrees C) induces COPII dissociation from membranes and slow exit from the endoplasmic reticulum in HeLa cells.

Low temperature induces a transport blockade at the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) in cultured cells. Our previous studies support that the primary effect of low temperature is the detachment of COPI complexes from membranes. In the present study, we have used immunofluorescence and cryoimmunoelectron microscopy to investigate the effects of low temperature on both COPII and clathrin coat complexes in HeLa cells. Strikingly, COPII proteins moved from membranes to the cytosol at 15 degrees C, accumulating into electron-dense areas. In agreement with this observation, we also showed that ER exit is delayed in cells cultured at this temperature. In contrast, clathrin coat is not affected. Together, our results demonstrate that low temperature induces COPII dissociation from membranes and slow exit from the endoplasmic reticulum.