A quantitative trait variant in Gabra2 underlies increased methamphetamine stimulant sensitivity

Psychostimulant (methamphetamine, cocaine) use disorders have a genetic component that remains mostly unknown. We conducted genome-wide quantitative trait locus (QTL) analysis of methamphetamine stimulant sensitivity. To facilitate gene identification, we employed a Reduced Complexity Cross between closely related C57BL/6 mouse substrains and examined maximum speed and distance traveled over 30 min following methamphetamine (2 mg/kg, i.p.). For maximum methamphetamine-induced speed following the second and third administration, we identified a single genome-wide significant QTL on chromosome 11 that peaked near the Cyfip2 locus (LOD = 3.5, 4.2; peak = 21 cM [36 Mb]). For methamphetamine-induced distance traveled following the first and second administration, we identified a genome-wide significant QTL on chromosome 5 that peaked near a functional intronic indel in Gabra2 coding for the alpha-2 subunit of the GABA-A receptor (LOD = 3.6-5.2; peak = 34-35 cM [66-67 Mb]). Striatal cis-expression QTL mapping corroborated Gabra2 as a functional candidate gene underlying methamphetamine-induced distance traveled. CRISPR/Cas9-mediated correction of the mutant intronic deletion on the C57BL/6J background to the wild-type C57BL/6NJ allele was sufficient to reduce methamphetamine-induced locomotor activity toward the wild-type C57BL/6NJ-like level, thus validating the quantitative trait variant (QTV). These studies show the power and efficiency of Reduced Complexity Crosses in identifying causal variants underlying complex traits. Functionally restoring Gabra2 expression decreased methamphetamine stimulant sensitivity and supports preclinical and human genetic studies implicating the GABA-A receptor in psychostimulant addiction-relevant traits. Importantly, our findings have major implications for studying psychostimulants in the C57BL/6J strain-the gold standard strain in biomedical research.

Genetic Modulation of Initial Sensitivity to Δ9-Tetrahydrocannabinol (THC) Among the BXD Family of Mice

Cannabinoid receptor 1 activation by the major psychoactive component in cannabis, Δ9-tetrahydrocannabinol (THC), produces motor impairments, hypothermia, and analgesia upon acute exposure. In previous work, we demonstrated significant sex and strain differences in acute responses to THC following administration of a single dose (10 mg/kg, i.p.) in C57BL/6J (B6) and DBA/2J (D2) inbred mice. To determine the extent to which these differences are heritable, we quantified acute responses to a single dose of THC (10 mg/kg, i.p.) in males and females from 20 members of the BXD family of inbred strains derived by crossing and inbreeding B6 and D2 mice. Acute THC responses (initial sensitivity) were quantified as changes from baseline for: 1. spontaneous activity in the open field (mobility), 2. body temperature (hypothermia), and 3. tail withdrawal latency to a thermal stimulus (antinociception). Initial sensitivity to the immobilizing, hypothermic, and antinociceptive effects of THC varied substantially across the BXD family. Heritability was highest for mobility and hypothermia traits, indicating that segregating genetic variants modulate initial sensitivity to THC. We identified genomic loci and candidate genes, including Ndufs2, Scp2, Rps6kb1 or P70S6K, Pde4d, and Pten, that may control variation in THC initial sensitivity. We also detected strong correlations between initial responses to THC and legacy phenotypes related to intake or response to other drugs of abuse (cocaine, ethanol, and morphine). Our study demonstrates the feasibility of mapping genes and variants modulating THC responses in the BXDs to systematically define biological processes and liabilities associated with drug use and abuse.

Sex and Strain Variation in Initial Sensitivity and Rapid Tolerance to Δ9-Tetrahydrocannabinol

Background and Objectives: For cannabis and other drugs of abuse, initial response and/or tolerance to drug effects can predict later dependence and problematic use. Our objective is to identify sex and genetic (strain) differences in initial response and rapid tolerance to Δ9–tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, between highly genetically divergent inbred mouse strains—C57BL/6J (B6) and DBA/2J (D2).

Experimental Approach: Sex and strain responses relative to baseline were quantified following daily exposure (i.p.) to 10 mg/kg THC or vehicle (VEH) over the course of 5 days. Dependent measures included hypothermia (decreased body temperature) and ataxia (decreased spontaneous activity in the open field), and antinociception (increase in tail withdrawal latency to a thermal stimulus). Initial sensitivity to THC was defined as the difference in response between baseline and day 1. Rapid tolerance to THC was defined as the difference in response between days 1 and 2.

Results: B6 exhibited greater THC-induced motor activity suppression and initial sensitivity to ataxia relative to the D2 strain. Females demonstrated greater levels of THC-induced hypothermia and initial sensitivity relative to males. Higher levels of THC-induced antinociception and initial sensitivity were observed for D2 relative to B6. Rapid tolerance to THC was observed for hypothermia and antinociception. Much less tolerance was observed for THC-induced ataxia. D2 exhibited rapid tolerance to THC-induced hypothermia and antinociception at time points associated with peak THC initial response. Likewise, at the peak initial THC response time point, females demonstrated greater levels of rapid tolerance to hypothermic effects relative to males.

Conclusions: Both sex and genetic factors drive variation in initial response and rapid tolerance to the ataxic, antinociceptive, and hypothermic effects of THC. As these traits directly result from THC activation of the cannabinoid receptor 1, gene variants between B6 and D2 in cannabinoid signaling pathways are likely to mediate strain differences in response to THC.

Comparison and Functional Genetic Analysis of Striatal Protein Expression Among Diverse Inbred Mouse Strains

C57BL/6J (B6) and DBA/2J (D2) inbred mouse strains are highly variable genetically and differ in a large number of behavioral traits related to striatal function, including depression, anxiety, stress response, and response to drugs of abuse. The genetic basis of these phenotypic differences are, however, unknown. Here, we present a comparison of the striatal proteome between B6 and D2 and relate differences at the protein level to strain differences at the mRNA level. We also leverage a recombinant inbred BXD population derived from B6 and D2 strains to investigate the role of genetic variation on the regulation of mRNA and protein levels. Finally, we test the hypothesis that differential protein expression contributes to differential behavioral responses between the B6 and D2 strain. We detected the expression of over 2,500 proteins in membrane-enriched protein fractions from B6 and D2 striatum. Of these, 160 proteins demonstrated significant differential expression between B6 and D2 strains at a 10% false discovery level, including COMT, GABRA2, and cannabinoid receptor 1 (CNR1)—key proteins involved in synaptic transmission and behavioral response. Similar to previous reports, there was little overlap between protein and transcript levels (25%). However, the overlap was greater (51%) for proteins demonstrating genetic regulation of cognate gene expression. We also found that striatal proteins with significantly higher or lower relative expression in B6 and D2 were enriched for dopaminergic and glutamatergic synapses and processes involved in synaptic plasticity [e.g., long-term potentiation (LTP) and long-term depression (LTD)]. Finally, we validated higher expression of CNR1 in B6 striatum and demonstrated greater sensitivity of this strain to the locomotor inhibiting effects of the CNR1 agonist, Δ9-tetrahydrocannabinol (THC). Our study is the first comparison of differences in striatal proteins between the B6 and D2 strains and suggests that alterations in the striatal proteome may underlie strain differences in related behaviors, such as drug response. Furthermore, we propose that genetic variants that impact transcript levels are more likely to also exhibit differential expression at the protein level.

Genetic Factors Mediate the Impact of Chronic Stress and Subsequent Response to Novel Acute Stress

Individual differences in physiological and biobehavioral adaptation to chronic stress are important predictors of health and fitness; genetic differences play an important role in this adaptation. To identify these differences we measured the biometric, neuroendocrine, and transcriptional response to stress among inbred mouse strains with varying degrees of genetic similarity, C57BL/6J (B), C57BL/6NJ (N), and DBA/2J (D). The B and D strains are highly genetically diverse whereas the B and N substrains are highly similar. Strain differences in hypothalamic-pituitary-adrenal (HPA) axis cross-sensitization were determined by plasma corticosterone (CORT) levels and hippocampal gene expression following 7-weeks of chronic mild stress (CMS) or normal housing (NH) and subsequent exposure to novel acute restraint. Fecal CORT metabolites and body and organ weights were also measured. All strains exposed to CMS had reduced heart weights, whereas body weight gain was attenuated only in B and N strains. Acute stress alone produced larger plasma CORT responses in the D and N strains compared to the B strain. CMS paired with acute stress produced cross-sensitization of the CORT response in the N strain. The N strain also had the largest number of hippocampal transcripts with up-regulated expression in response to stress. In contrast, the D strain had the largest number of transcripts with down-regulated expression following CMS and acute stress. In summary, we observed differential responses to CMS at both the physiological and molecular level among genetically diverse strains, indicating that genetic factors drive individual differences in experience-dependent regulation of the stress response.

Identification of a Functional Non-coding Variant in the GABA A Receptor α2 Subunit of the C57BL/6J Mouse Reference Genome: Major Implications for Neuroscience Research

GABA type-A (GABA-A) receptors containing the α2 subunit (GABRA2) are expressed in most brain regions and are critical in modulating inhibitory synaptic function. Genetic variation at the GABRA2 locus has been implicated in epilepsy, affective and psychiatric disorders, alcoholism and drug abuse. Gabra2 expression varies as a function of genotype and is modulated by sequence variants in several brain structures and populations, including F2 crosses originating from C57BL/6J (B6J) and the BXD recombinant inbred family derived from B6J and DBA/2J. Here we demonstrate a global reduction of GABRA2 brain protein and mRNA in the B6J strain relative to other inbred strains, and identify and validate the causal mutation in B6J. The mutation is a single base pair deletion located in an intron adjacent to a splice acceptor site that only occurs in the B6J reference genome. The deletion became fixed in B6J between 1976 and 1991 and is now pervasive in many engineered lines, BXD strains generated after 1991, the Collaborative Cross, and the majority of consomic lines. Repair of the deletion using CRISPR-Cas9-mediated gene editing on a B6J genetic background completely restored brain levels of GABRA2 protein and mRNA. Comparison of transcript expression in hippocampus, cortex, and striatum between B6J and repaired genotypes revealed alterations in GABA-A receptor subunit expression, especially in striatum. These results suggest that naturally occurring variation in GABRA2 levels between B6J and other substrains or inbred strains may also explain strain differences in anxiety-like or alcohol and drug response traits related to striatal function. Characterization of the B6J private mutation in the Gabra2 gene is of critical importance to molecular genetic studies in neurobiological research because this strain is widely used to generate genetically engineered mice and murine genetic populations, and is the most widely utilized strain for evaluation of anxiety-like, depression-like, pain, epilepsy, and drug response traits that may be partly modulated by GABRA2 function.

FP2-3 Ten years of paediatric neuro-oncology surgery: quantifying and predicting complications after surgery for intracranial tumour excision

Objectives

To measure complications of paediatric neurooncology surgery using the Clavien Dindo grading scale, and identify predictors of surgical morbidity.

Design

Retrospective review of prospectively collected data.

Subjects

All paediatric patients treated with craniotomy for excision of intracranial tumour between 2008 and 2017 in a single tertiary paediatric neurosurgery centre.

Methods

Demographics, surgical details and perioperative complications were prospectively recorded between 0 and 30 days post operatively. These were retrospectively graded using the CD scale. Data analysis was done in R using logistic regression. Significance was defined as p<0.05

Results

Between 3/1/2008 and 21/12/2017 there were 322 operations, on 254 patients (142 Male). Median age at surgery was 9 years (IQR 4–13 years). 48% were without complication on the CD scale. Maximum CD grade complication for each procedure was 1 in 11%, 2 in 19%, 3A in 2%, 3B in 14%, and 4 in 0.6% of operations. 30 day mortality was 0.9%. CD grade of 3B or over was associated with infratentorial tumours (OR 2.24; CI 1.10–4.68; p=0.004) and WHO grade III tumours (OR 4.12; CI 1.56–10.86; p=0.028).

Conclusions

Complications in paediatric neurooncology surgery are common overall, but our results are favourable in comparison to the literature. The CD scale has limitations in neurosurgery but gives insight into the health economic impact of complications. Infratentorial tumours, and WHO grade III tumours were associated with increased morbidity.

TP1-10 Non tumour brain biopsies in alder hey paediatric neurosurgery

Objectives

To review the utility of non-tumour brain biopsies in Alder Hey Children’s NHS Foundation Trust Paediatric Neurosurgery Department.

Methods

Operative records were searched for ‘biopsy’. Case notes were reviewed for referral source, histology, surgical complication and outcome. Tumour, epilepsy and non-brain biopsy cases were excluded.

Results

83 ‘biopsy’ cases were identified between 2008 and 2017. 31 tumour, 5 epilepsy, 2 infections and 28 non brain/other biopsies were excluded. 17 brain biopsies for non-tumour causes were seen. 15 patients were referred by neurology, 2 by rheumatology. 14 underwent a craniotomy/mini-craniotomy, 3 had burrholes.4 biopsies were non diagnostic, 2 were abnormal but inconclusive for diagnosis. Diagnoses included: 3 demyelinating lesions, 2 normal brain tissue, 1 neurosarcoidosis, 1 autoimmune encephalitis, 1 definite Rasmussen’s Encephalitis, 1 possible Rasmussen’s Encephalitis, 1 systemic lupus erythematosus associated CNS vasculitis, 1 inflammatory infiltrate (secondary to hydrocephalus/ventriculitis), 1 patient developed a late wound infection. No other surgical morbidities/mortalities were recorded. 11 of these cases had a change in management or the treating team were reassured due to the result of the biopsy (i.e. were able to start immunomodulatory drugs in the absence of infection).

Conclusions

65% of brain biopsies were diagnostic. 71% of biopsies either changed management or reassured the treating team about a line of management. The procedure is low risk with 0.06% morbidity and 0% mortality.

P98 A decade of primary tumours of the spine in the paediatric population

Objectives

Primary spinal tumours in children are rare and poorly understood; we review 10 years of surgical experience.

Design

Retrospective review of prospectively maintained database.

Subjects

Children receiving surgical management of primary spinal tumours in a single, tertiary paediatric neurosurgery centre.

Methods

Operations for primary spinal tumours were abstracted from our prospectively maintained surgical database and supplemented with data from case notes, operative records, and imaging studies.

Results

Between 2008 and 2017, 37 procedures were performed on 29 patients (19 male; Median age 7.5 years, IQR 2–11.25). 28 had their primary procedure in our unit: 21 excisions, and 7 biopsies (of which 5 proceeded to further surgery). Tumours were classified as extradural (10), intradural extramedullary (3), intradural intramedullary (11) or bony (4). Tumours were found at the following levels: Cervical (8; 29%), Cervicothoracic (2; 7.1%), Thoracic (10; 36%), Thoracolumbar (3; 11%), Lumbar (2; 7.1%), Lumbosacral (2; 7.1%) and Sacral (1; 3.6%). Histology comprised: Pilocytic Astrocytoma (6), Other Astrocytoma (4), Schwannoma (3), Ewing Sarcoma (2), Langerhans cell histiocytosis (2), Lymphoma (2), Neurofibroma (2), and others (7) including one Myxopapillary Ependymoma.

Conclusions

The rarity and heterogeneity of paediatric spinal tumours makes treatment challenging. We propose a national online registry including a tissue bank, and invite collaboration with other units.

Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. Indeed, research focusing on the discovery of new potential therapeutic targets using genetically altered mice requires a reliable, long-term assessment of the systemic arterial pressure variation. Currently, the gold standard for obtaining long-term measurements of blood pressure in ambulatory mice uses implantable radio-transmitters, which require artery cannulation. This technique eliminates the need for tethering, restraining, or anesthetizing the animals which introduce stress and artifacts during data sampling. However, arterial blood pressure monitoring in mice via catheterization can be rather challenging due to the small size of the arteries. Here we present a step-by-step guide to illustrate the crucial key passages for a successful subcutaneous implantation of radio-transmitters and carotid artery cannulation in mice. We also include examples of long-term blood pressure activity taken from freely moving mice after a period of post-surgery recovery. Following this procedure will allow reliable direct blood pressure recordings from multiple animals simultaneously.

Abstract 419: Stim1 is Associated With Calcium Microdomains That are Required for Myofilament Remodeling and Signaling During Cardiac Hypertrophy

Stromal Interaction Protein 1 (STIM1) is the intracellular component of the store operated calcium channels. It is a ubiquitous Ca2+ sensor, prevalently located in the sarcoplasmic reticulum. In non-excitable cells, STIM1 is a key element in the generation of Ca2+signals that lead to gene expression and cell proliferation. A growing body of literature now suggests that STIM1 is important for normal heart function and plays a key role in the development of pathological cardiac hypertrophy. However, the precise mechanisms involving STIM1 and the Ca2+ signaling in excitable cells are not clearly established. We show that in neonatal rat cardiomyocytes, the spatial properties of STIM1-dependent Ca2+ signals determine restricted Ca2+ microdomains that regulate myofilaments remodeling and spatially segregated activation of pro-hypertrophic factors. Indeed, in vivo data obtained from an inducible cardiac restricted STIM1 knockout mouse, exhibited left ventricular dilatation associated with reduced cardiac contractility, which was corroborated by impaired single cell contractility. Furthermore, mice lacking STIM1 showed less adverse structural remodeling in response to pathological pressure overload-induced cardiac hypertrophy (transverse aortic constriction, TAC). We further show that the Ca2+ pool associated with STIM1 is the ON switch for extracellular signal-regulated kinase (ERK1/2)-mediated cytoplasm to nucleus signaling. These results highlight how STIM1-dependent Ca2+ microdomains have a major impact on intracellular Ca2+ homeostasis, cytoskeletal remodeling, signaling and cardiac function, even when excitation-contraction coupling is present.

Cerebellopontine angle oligodendroglioma in a child: first case report

The reported incidence of oligodendrogliomas in the paediatric population is less than 1 %. The posterior fossa is a rare location, with the vast majority arising in the cerebral hemispheres. We report the first paediatric case of a WHO grade II oligodendroglioma arising in the cerebellopontine angle (CPA). CPA oligodendrogliomas in children appear to behave aggressively and adjuvant therapy must be considered early; especially when complete resection cannot be achieved.

Costs and outcomes associated with hospitalizations for venous thromboembolic disease in patients with malignant neoplasm

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Background: Venous thromboembolic disease (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE) is a common occurrence in oncology, as patients with cancer have a greatly increased risk of VTE. Costs of VTE treatment are significant, including direct costs (expenditures for procedures, tests, medications, and services), indirect morbidity costs (lost income from work due to the condition or disability), and indirect mortality costs (lost income due to early mortality). Costs associated with VTE contribute to the overall cost of cancer care, however studies that examine the cost of care for oncology patients that develop VTEs are limited. Methods: A retrospective cohort study identified patients with cancer hospitalized during January 2006 through May 2008 using a large US healthcare database (>342 inpatient facilities across all US regions, ∼ 11 million patients and > 300 million charge- detail records). Patients with an ICD-9-CM code for malignant neoplasm (140.xx-208.xx) in combination with DVT or PE (415.11,415.19, 453.4,453.41,453.42) were included. Using Aspen's charge cost model, the hospital's clinical, utilization and billing, and cost accounting records healthcare cost, LOS, and mortality rates associated with these hospitalizations were calculated. Results: Data from 74 facilities with a mean bed size of 349 was utilized. A total of 77% of these facilities were not classified as teaching hospitals. Overall 1136 inpatients were identified with a diagnosis of malignant neoplasm and either DVT or PE. Table 1 shows the results. Conclusions: DVT/PE contributes to the cost of cancer treatment and is a considerable cost driver. Additionally, human costs are high. Aggressive practices to prevent these complications can result in a lower healthcare burden. In an era of restricted resources and value based purchasing, these data can be used to prioritize resource utilization.

[Table: see text]

[Table: see text]

Costs and outcomes associated with febrile neutropenia-related hospitalizations across patients with varying cancer types: A retrospective analysis

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Background: Neutropenia, the major dose-limiting toxicity of chemotherapy, is a frequent, often serious, and sometimes fatal complication of myelosuppressive chemotherapy. Its economic and clinical impact is often under-appreciated, and thus this study evaluates the contribution of febrile neutropenia (FN) by tumor type as related to healthcare cost and mortality. Methods: FN patients in this study were identified as having cancer (ICD-9-CM: 140.xx - 208.xx), neutropenia (288.0x) and either opportunistic infections (110 total codes) or fever of unknown origin (780.6) who were hospitalized between 1/05 and 6/08 in a retrospective cohort study from the Aspen US healthcare database (∼11 million pts, >342 inpatient facilities, and >300 million charge-detail records). Unadjusted mean healthcare cost of hospitalization, length of hospital stay (LOS), and mortality rates were calculated, stratifying by cancer type (breast, metastatic breast, and lung cancers, non-Hodgkin lymphoma (NHL), or other hematologic tumors). Results: Among 598 hospitalized patients (mean age 63 years; 53% female) with cancer experiencing FN, the mean cost of hospitalization, LOS and mortality varied significantly by tumor type ( Table ). Conclusions: FN hospitalizations are costly and may be associated with significant mortality. Considerable variations exist across cancer types for hospitalization costs, LOS and mortality. The tumor type is important in assessing the economic and clinical impact of FN hospitalizations.

[Table: see text]

[Table: see text]

First Report of Arceuthobium hondurense in Mexico

Honduran dwarf mistletoe (Arceuthobium hondurense Hawksw. & Wiens) is a rare dwarf mistletoe previously known only from Honduras (1,2). In March 2000 we collected a dwarf mistletoe from approximately 7 km west of San Cristobal de las Casas, Chiapas, Mexico near Route 190 (elevation 2,440 m), which was morphologically similar to A. hondurense (1). This population had initially been classified as A. nigrumHawksw. & Wiens (1). However, our morphological measurements and analysis of nuclear rDNA ITS sequences of A. hondurense plants from Honduras (GenBank No. AF325969) and the plants from Chiapas (AF325970) have confirmed that the Chiapan population is A. hondurense and not A. nigrum. An additional population of A. hondurense was discovered in Chiapas approximately 11 km west of Oxchuc near Route 186 (elevation 2160 m). Both of the Chiapan populations of A. hondurense were parasitizing Pinus tecunumanii(Schw.) Eguiluz et Perry. Specimens of A. hondurense from Chiapas were deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff. This is the first report of A. hondurense in Mexico and extends its known distribution from northwestern Honduras (3) by approximately 500 km. Although A. hondurense has not been observed in the pine forests of Guatemala, it is probable that it also occurs there (1). References: (1) F. G. Hawksworth and D. Wiens. 1996. Dwarf Mistletoes: Biology, Pathology, and Systematics. USDA Agric. Handb. 709. (2) R. Mathiasen et al. Phytologia 36:211, 1998. (3) R. Mathiasen et al. Plant Dis. 84:372, 2000.

Performance of older depressed patients on two cognitive malingering tests: false positive rates for the Rey 15-item memorization and dot counting tests

To our knowledge, no investigations have been undertaken to determine whether depression impacts performance on two commonly used tests to detect malingering of cognitive symptoms, the Rey 15-item Memorization Test and the Rey Dot Counting Test. This is a critical issue because of the high rate of depressive symptoms in patients with neurological conditions. It was hypothesized that depressed individuals, especially those with more severe depression, might be at risk for failing the tests, because these patients exhibit mild deficits in mental speed, visual perceptual/spatial skills, and visual memory, abilities required for successful completion of the malingering tests. However, examination of test performance in 64 older participants with major depression generally revealed very low false positive rates for most test scores, and severity of depression was unrelated to test scores. These results add to accumulating data supporting the validity of these cognitive malingering tests by documenting few false positive identifications.

First Report of Psittacanthus angustifolius on Pines in Mexico and Guatemala

The mistletoe Psittacanthus angustifolius Kuijt (Loranthaceae) is a common parasite of pines in Honduras (2). In March we observed this mistletoe parasitizing a pine that Farjon and Styles (1) have classified as Pinus tecunumanii Eguiluz & J. P. Perry 4 km south of Jitotol, Chiapas, Mexico. The taxonomy of this host in Chiapas is controversial as Perry (3) classifies the Chiapas populations of this pine as Pinus oocarpa var. ochoterenai Martinez. We also observed P. angustifolius on P. oocarpa Schiede 4 km north of Jitotol. In addition, we found this mistletoe parasitizing Pinus maximinoi H. E. Moore approximately 15 km west of Ocosingo, Chiapas. In Guatemala, we observed P. angustifolius on P. oocarpa at several locations north and south of La Cumbre, Department Baja Verapaz. This mistletoe appears to be less common in Chiapas and Guatemala than it is in Honduras. We did not observe this mistletoe damaging its pine hosts in Mexico or Guatemala. This is the first report of P. angustifolius in both Mexico and Guatemala and the first report of this mistletoe on Pinus tecunumanii (or Pinus oocarpa var. ochoterenai). Specimens of P. angustifolius from the above pine hosts have been deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff. References: (1) A. Farjon and B. Styles. Pinus (Pinaceae), Flora Neotropica, Monogr. 75, New York Botanical Garden, 1997. (2) Mathiasen et al. Plant Dis. 84:203, 2000. (3) J. Perry. The Pines of Mexico and Central America, Timber Press, Portland, Oregon, 1991.

First Report of Psittacanthus angustifolius on Pinus oocarpa and Pinus maximinoi

The mistletoe Psittacanthus angustifolius Kuijt (Loranthaceae) was first described in 1987 on Pinus from Nicaragua near the Honduran border, but the species of pine was not designated (1). Kuijt (1) speculated that this mistletoe probably also occurs in Honduras. During March and October 1999 we observed P. angustifolius parasitizing Pinus oocarpa Schiede in the departments of Choluteca, Francisco Morazan, El Paraiso, Intibuca, Lempira, and Olancho in Honduras. This mistletoe appears to be a very common parasitic plant on pines in Honduras and is associated with host mortality. We also observed P. angustifolius parasitizing Pinus maximinoi H.E. Moore at two locations in the department of Lempira: one infection on a single tree 1.5 km east of El Matazano (elevation 1,400 m) and six and eight infections on two trees 0.5 km west of the main entrance to Celaque National Park east of Gracias (elevation 1,200 m). This is the first report of P. angustifolius in Honduras and the first report of this mistletoe on Pinus oocarpa and Pinus maximinoi. Specimens of P. angustifolius from Pinus oocarpa and Pinus maximinoi have been deposited at the Herbario, Escuela Nacional de Ciencias Forestales, Siguatepeque, Honduras, and at the Deaver Herbarium, Northern Arizona University, Flagstaff. Reference: (1) J. Kuijt. Ann. Mo. Bot. Gard. 74:511, 1987.

Effects of aging on efficiency of task switching in a variant of the trail making test

The Trail Making Test (TMT; R. M. Reitan, 1958, 1992) is extensively used in research in neuropsychology and in aging, in part because it has been postulated to reflect executive processes, such as planning and switching. However, neurocognitive and individual-difference-based analyses of this test are complicated because of different spatial arrangements of targets, the use of letters only in Version B, and potential order effects when Version A is administered prior to Version B. The present article examines a variant of a TMT (called the Connections Test) that attempts to remedy these deficiencies. A structural equation model suggested that there were no direct effects of age on either the nonalternating or alternating versions of the Connections Test (analogous to TMT Versions A and B, respectively); rather, all age-related effects were mediated through effects on perceptual speed. Moreover, although the nonalternating and alternating versions were strongly related to one another, only the latter had significant independent relations with measures of higher order cognition.

Complications and outcome after acute stroke. Does dysphagia matter?

BACKGROUND AND PURPOSE

The published data on the relationship between dysphagia and both outcome and complications after acute stroke have been inconclusive. We examined the relationship between these, using bedside assessment and videofluoroscopic examination.

METHODS

We prospectively studied 121 consecutive patients admitted with acute stroke. A standardized bedside assessment was performed by a physician. We performed videofluoroscopy blinded to this assessment within 3 days of stroke onset and within a median time of 24 hours of the bedside evaluations. The presence of aspiration was recorded. Mortality, functional outcome, lengthy of stay, place of discharge, occurrence of chest infection, nutritional status, and hydration were the main outcome measures.

RESULTS

Patients with an abnormal swallow (dysphagia) on bedside assessment had a higher risk of chest infection (P=.05) and a poor nutritional state (P=.001). The presence of dysphagia was associated with an increased risk of death (P=.001), disability (P=.02), length of hospital stay (P<.001), and institutional care (P<.05). When other factors were taken into account, dysphagia remained as an independent predictor of outcome only with regard to mortality. The use of videofluoroscopy in detecting aspiration did not add to the value of bedside assessment.

CONCLUSIONS

Bedside assessment of swallowing is of use in identifying patients at risk of developing complications. The value of routine screening with videofluoroscopy to detect aspiration is questioned.

Genomic characterization of hepatitis C virus isolates from Argentina

Thirty-three Argentinian patients infected with hepatitis C virus (HCV) were studied for viral genotyping. The patients included 10 hemophiliac and 4 polytransfused children and 19 adults: 3 polytransfused, 7 dialyzed and 9 sporadic cases. Core-based genotyping permitted the classification of 31 samples. Genotypes II, I and V were the most frequent: 21 (63.6%), 16 (48.4%) and 10 (30.3%) of the 33 patients, respectively. Only one polytransfused patient carried genotype IV. Genotype II was detected in 7 out of 9 sporadic cases. Thirteen patients (39.3%) were coinfected with two genotypes, and 2 others were coinfected with three genotypes. The remaining 2 samples which could not be typed were characterized following the restriction fragment length polymorphism (RFLP) method, and were classified as type 1. One of these had two consecutive transitional mutations in the 5' untranslated region (5' UTR).

Glial cell-specific expression of the serotonin 2 receptor gene: selective reactivation of a repressed promoter

The 5' flanking region of the 5-HT2 receptor gene has been cloned, sequenced and its transcriptional regulatory functions analyzed. The promoter lacks an identifiable TATA motif, and utilizes at least 11 clustered start sites. Promoter function was analyzed by transient assays in rat C6 glioma cells, which were shown to express the endogenous 5-HT2 receptor gene, as well as in rat CREF and human HeLa cells which do not express the endogenous gene. The basal promoter functioned equally well in all three cell lines; and a repression domain, located upstream of the basal promoter, inhibited activity of the promoter in all three cell lines. A far upstream cell specific activator domain restored promoter activity in C6 glioma cells, but did not reactivate the silenced promoter in CREF or HeLa cells. The upstream activator domain, repressor domain and basal promoter functioned in concert to achieve cell type specific expression. The activator domain did not direct C6 glioma cell specific expression in the absence of the repressor domain or in constructs carrying a heterologous basal promoter. These results indicate that glial cell expression of the 5-HT2 receptor gene is achieved through a cell type specific reactivation of a repressed promoter.

Pediatric sedation: short-term effects

A prospective investigation on the short-term effects of various sedation regimens on 549 nonhospitalized magnetic resonance (MR) patients was performed. The drugs evaluated were chloral hydrate, pentobarbital, midazolam, and diazepam (fentanyl was used for enhancement after any of these drugs). The overall safety and efficacy were quite good with all the regimens. Overall, 84% of children slept less than 8 h after the examination, 90% were drowsy and/or unsteady for less than 8 h after they awoke, and 97% resumed their usual activities by 24 h. Significant hyperactivity was seen only with pentobarbital and occurred in 8.4% of children over 8 years of age. The multiple-dose regimen of pentobarbital and fentanyl had a significant short-term effect on the children less than 8 years of age, with 35% sleeping longer than 8 h after the MR. Ten children who had needed the multiple-dose pentobarbital regimen or who had failed prior pentobarbital sedation presented for repeat sedation. Midazolam was effective in 9 of these 10 children.