Val/Met BDNF as a genetic risk for a false sense of security in post-discharge suicide risk

BACKGROUND

The time after discharge from psychiatric inpatient care is one of the most dangerous periods in terms of suicide risk. Predicting who is at higher risk could help with resource allocation to assure patients at high risk of suicide attempts are most closely followed. We previously showed that inpatients who improve their suicide ideation levels faster while in inpatient treatment are the ones with highest rates of post-discharge suicide. Here, we studied the possible genetic underpinnings associated with such risk.

METHOD

We recorded the slope of suicide ideation recovery of 710 psychiatric inpatients from which we studied two genetic variants likely associated with suicide risk: The serotonin transporter variant 5-HTTLPR, and the BDNF gene variant Val66Met.

RESULTS

We found that inpatients carrying the BDNF Met variant (hypothesized as conferring higher suicide risk) improved their suicide ideation scores faster than Val/Val carrying inpatients. No significant association was found for 5-HTTLPR.

LIMITATIONS

The present sample was genetically homogenous, and future research should replicate these findings on a more diverse sample.

CONCLUSIONS

In conclusion, we found a paradoxical result: Carrying the BDNF Met variant allows inpatients to improve faster, which was shown to confer higher risk at the post-discharge period. This may explain some inconsistencies in the literature in terms of the role of BDNF in suicide ideation and attempts.

Emotional self-regulation, impulsivity, 5-HTTLPR and tobacco use behavior among psychiatric inpatients

BACKGROUND

While the serotonin transporter (SLC6A4) gene, 5-HTTLPR, interacts with the social environment to influence both emotional self-regulation and smoking behavior, less is known about interactions between emotional self-regulation and 5-HTTLPR or their joint influence on tobacco use. Here, we examined such interactions among psychiatric inpatients, the population with the highest rates of smoking.

METHODS

Participants (506 adults) were psychiatric inpatients at The Menninger Clinic in Houston TX between 2012 and 16. Most were white (89%), male (55%), with a mean age of 32.3 years. Participants completed the Difficulties in Emotional Regulation Scale (DERS) at admission. We examined interactions with smoking among three DERS subscales and 5-HTTLPR, controlling for sex, race and age.

RESULTS

Smoking rates were higher among those with the 5-HTTPLR L'L' genotype compared to peers carrying an S' allele (47.9% vs. 37.4%, respectively). Among S' allele carrying participants, impulse control difficulties (OR = 1.09; 95%CI: 1.03-1.14) and lack of emotion clarity (OR = 1.06; 95%CI: 1.00-1.11) increased risk for ever using tobacco, while accessing more ways to regulate emotion (OR = 0.95; 95%CI: 0.92-0.99) offered a protective effect against ever using tobacco. Neither demographic nor DERS covariates were associated with using tobacco among the L'L' group.

LIMITATIONS

This ethnically homogenous sample limits generalizability and using a binary outcome can over-estimate a gene environment interaction effect.

CONCLUSIONS

Emotional self-regulation exerts a stronger influence on using tobacco among carriers of an S' allele of 5-HTTLPR than peers with the L'L' genotype. Promoting emotional self-regulatory skills may have benefits for preventing tobacco use.

Polysomnography Following Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Introduction

Sleep disturbances are common following traumatic brain injury (TBI) worsening morbidity and other neuropsychiatric symptoms. Post-TBI alterations in sleep architecture require further study.

Objectives

(1) To evaluate polysomnographic measures of sleep architecture in participants with history of TBI compared to controls and as meta-analyses of pooled means. (2) To evaluate effects of timing and severity of TBI on polysomnographic outcomes.

Methods

PRISMA compliant systematic review was conducted of MEDLINE, PsycINFO, EMBASE and Scopus. Inclusion criteria: 1) reporting polysomnography in the context of TBI and 2) operationalizing TBI using clear/formalized criteria. Data were pooled in random-effects meta-analyses with outcomes expressed as mean differences (MD).

Results

In participants with TBI, sleep was comprised of 19.39% REM sleep, 8.13% N1, 51.18% N2, and 17.53% N3, as determined by meta-analyses of single means. Total sleep time was reduced in chronic (>6 months) TBI compared to acute-intermediate TBI (<6 months) (p=0.01). Compared to controls, participants with TBI differed with increased N1 sleep (MD=0.64%; 95%CI=0.02,1.25; p=0.04), reduced sleep efficiency (MD=-1.65%; 95%CI=-3.18,-0.12; p=0.03), and reduced sleep latency on the multiple sleep latency test (MD=-5.90mins; 95%CI=-10.09,-1.72; p<0.01). On sub-group analyses, participants with mild TBI differed from controls with reduced total sleep time (MD=-29.22mins, 95%CI=-54.16,-4.27; p=0.02). Similarly, participants with acute-intermediate TBI exhibited increased sleep latency compared to controls (MD=8.96mins; 95%CI=4.07,13.85; p<0.01) and differed significantly from participants with chronic TBI (X2(1,N=608)=6.54; p=0.01).

Conclusions

Sleep architecture is altered following TBI with potential implications regarding functional outcomes and recovery. These alterations appear to differ based on severity of injury and time since injury.

Disclosure

No significant relationships.

Decreased Brain Ventricular Volume in Psychiatric Inpatients with Serotonin Reuptake Inhibitor Treatment

Background

Brain ventricles have been reported to be enlarged in several neuropsychiatric disorders and in aging. Whether human cerebral ventricular volume can decrease over time with psychiatric treatment is not well-studied. The aim of this study was to examine whether inpatients taking serotonin reuptake inhibitors (SRI) exhibited reductions in cerebral ventricular volume.

Methods

Psychiatric inpatients, diagnosed mainly with depression, substance use, anxiety, and personality disorders, underwent two imaging sessions (Time 1 and Time 2, approximately 4 weeks apart). FreeSurfer was used to quantify volumetric features of the brain, and ANOVA was used to analyze ventricular volume differences between Time 1 and Time 2. Inpatients' brain ventricle volumes were normalized by dividing by estimated total intracranial volume (eTIV). Clinical features such as depression and anxiety levels were collected at Time 1, Time 1.5 (approximately 2 weeks apart), and Time 2.

Results

Inpatients consistently taking SRIs (SRI + , n = 44) showed statistically significant reductions of brain ventricular volumes particularly for their left and right lateral ventricular volumes. Reductions in their third ventricular volume were close to significance (p = .068). The inpatients that did not take SRIs (SRI-, n = 25) showed no statistically significant changes in brain ventricular volumes. The SRI + group also exhibited similar brain structural features to the healthy control group based on the 90% confidence interval comparsions on brain ventricular volume parameters, whereas the SRI- group still exhibited relatively enlarged brain ventricular volumes after treatment.

Conclusions

SRI treatment was associated with decreased brain ventricle volume over treatment.

The gut microbiota is associated with psychiatric symptom severity and treatment outcome among individuals with serious mental illness

BACKGROUND

Emerging evidence implicates the gut microbiota in central nervous system functioning via its effects on inflammation, the hypothalamic-pituitary axis, and/or neurotransmission. Our understanding of the cellular underpinnings of the brain-gut relationship is based almost exclusively on animal models with some small-scale human studies. This study examined the relationship between the gut microbiota and psychiatric symptom severity and treatment response among inpatients with serious mental illness.

METHOD

We collected data from adult inpatients (N = 111). Measures of diagnoses, suicide severity, trauma, depression, and anxiety were collected shortly after admission, while self-collected fecal swabs were collected early in the course of hospitalization and processed using 16S rRNA gene sequencing and whole genome shotgun sequencing methods.

RESULTS

Results indicate that depression and anxiety severity shortly after admission were negatively associated with bacterial richness and alpha diversity. Additional analyses revealed a number of bacterial taxa associated with depression and anxiety severity. Gut microbiota richness and alpha diversity early in the course of hospitalization was a significant predictor of depression remission at discharge.

CONCLUSIONS

This study is among the first to demonstrate a gut microbiota relationship with symptom severity among psychiatric inpatients as well as a relationship to remission of depression post-treatment. These findings are consistent with animal models and limited human studies as well as with the broader literature implicating inflammation in the pathophysiology of depression. These findings offer the foundation for further studies of novel therapeutic approaches to the treatment, prevention of, or recurrence of serious mental illness.

Classifying suicidal behavior with resting-state functional connectivity and structural neuroimaging

OBJECTIVE

About 80% of patients who commit suicide do not report suicidal ideation the last time they speak to their mental health provider, highlighting the need to identify biomarkers of suicidal behavior. Our goal is to identify suicidal behavior neural biomarkers to classify suicidal psychiatric inpatients.

METHODS

Eighty percent of our sample [suicidal (n = 63) and non-suicidal psychiatric inpatients (n = 65)] was used to determine significant differences in structural and resting-state functional connectivity measures throughout the brain. These measures were used in a random forest classification model on 80% of the sample for training the model.

RESULTS

The model built on 80% of the patients had sensitivity = 79.4% and specificity = 72.3%. This model was tested on an independent sample (20%; n = 32) with sensitivity = 81.3% and specificity = 75.0% for confirming the generalizability of the model. Altered resting-state functional connectivity features from frontal and middle temporal regions, as well as the amygdala, parahippocampus, putamen, and vermis were found to generalize best.

CONCLUSION

This work demonstrates neuroimaging (an unbiased biomarker) can be used to classify suicidal behavior in psychiatric inpatients without observing any clinical features.

Evaluating and Managing Sleep Disorders in the Parkinson's Disease Clinic

Parkinson's disease is a multi-systems neurodegenerative disorder that is characterized by a combination of motor and non-motor symptoms. Non-motor symptoms of Parkinson's disease comprise a variety of cognitive, neuropsychiatric, autonomic, sensory, and sleep complaints. Although sleep disruption represents one of the most common non-motor symptom complaints among Parkinson's disease patients, recommendations regarding effective evaluation and management strategies for this specific population remain limited. This review gives an evidence based summary of the available treatment options and management strategies for the sleep complaints commonly encountered by patients with Parkinson's disease.

Blood meal sources of wild and domestic Triatoma infestans (Hemiptera: Reduviidae) in Bolivia: connectivity between cycles of transmission of Trypanosoma cruzi

Background

Chagas disease is a major public health problem in Latin America. Its etiologic agent, Trypanosoma cruzi, is mainly transmitted through the contaminated faeces of blood-sucking insects called triatomines. Triatoma infestans is the main vector in various countries in South America and recently, several foci of wild populations of this species have been described in Bolivia and other countries. These wild populations are suspected of affecting the success of insecticide control campaigns being carried out in South America. To assess the risk that these T. infestans populations pose to human health, it is helpful to determine blood meal sources.

Methods

In the present work, blood meals were identified in various Bolivian wild T. infestans populations and in three specific areas, in both wild and intra-peridomestic populations to assess the links between wild and domestic cycles of T. cruzi transmission. PCR-HDA and sequencing of Cytb gene were used to identify these blood meal sources.

Results and discussion

Fourteen vertebrate species were identified as wild blood meal sources. Of those, the most prevalent species were two Andean endemic rodents, Octodontomys gliroides (36 %) and Galea musteloides (30 %), while humans were the third most prevalent source (18.7 %). Of 163 blood meals from peridomestic areas, more than half were chickens, and the others were generally domestic animals or humans. Interestingly, blood from wild animals was identified in triatomines captured in the peridomestic and domestic environment, and blood from domestic animals was found in triatomines captured in the wild, revealing links between wild and domestic cycles of T. cruzi transmission.

Conclusion

The current study suggests that wild T. infestans attack humans in the wild, but is also able to bite humans in domestic settings before going back to its natural environment. These results support the risk to human health posed by wild populations of T. infestans.

Transcranial Magnetic Stimulation and Deep Brain Stimulation in the treatment of alcohol dependence

Alcohol dependence is a major social, economic, and public health problem. Alcoholism can lead to damage of the gastrointestinal, nervous, cardiovascular, and respiratory systems and it can be lethal, costing hundreds of billions to the health care system. Despite the existence of cognitive-behavioral therapy, psychosocial interventions, and spiritually integrated treatment to treat it, alcohol dependence has a high relapse rate and poor prognosis, albeit with high interindividual variability. In this review, we discuss the use of two neuromodulation techniques, namely repetitive transcranial magnetic stimulation (rTMS) and deep brain stimulation (DBS), and their advantages and disadvantages compared to first-line pharmacological treatment for alcohol dependence. We also discuss rTMS and DBS targets for alcohol dependence treatment, considering experimental animal and human evidence, with careful consideration of methodological issues preventing the identification of feasible targets for neuromodulation treatments, as well as inter-individual variability factors influencing alcoholism prognosis. Lastly, we anticipate future research aiming to tailor the treatment to each individual patient by combining neurofunctional, neuroanatomical and neurodisruptive techniques optimizing the outcome.

Variations in time and space of an Andean wild population of T. infestans at a microgeographic scale

Background

Wild populations of Triatoma infestans are now believed to be the source of reinfestation of dwellings in some Andean areas and could impede the full achievement of vector control campaigns in this region. Given the poor knowledge of these populations in natural conditions, their basic biology traits, such as monthly demographic variations and movements of individuals, were explored.

Methods

A previously identified wild population of T. infestans in a field adjacent to a group of isolated houses in an Andean valley (department of La Paz, Bolivia) was explored using regular capture assays over 13 months in 50 sites selected at the beginning of the study. The capture-mark-recapture method was applied monthly using mouse-baited adhesive traps for captures and fingernail polish of different colors for the marking.

Results

The monthly capture assays did not show significant differences between rainy and dry seasons, showing evidence for a certain stability of the wild T. infestans population with only the nymph population tending to decline during the middle of the rainy season when rain is more intensive. Throughout the study, the monthly average number of bugs was 51.1 ± 25.3 per assay, 91.1% were nymphs, and they were found at 30 of the 50 sites (60%). The number of times a site was positive varied from one to 13. Site infestation was associated with the underground position of the traps, and rocks around and in the surroundings of the traps. The recaptures after marking were successful (138 recaptures over the study). The marking made it possible to detect for 14.5% of the recaptures significant movements of adults (up to 168 m) and nymphs (up to 34 m). Some bugs (nymphs and females) were recaptured after 5 months. For adults, recaptures (46 in total) mostly occurred between September and March. Females were recaptured twice as frequently as males.

Conclusion

The Andean wild populations of T. infestans showed a strong spatial and temporal stability during the year-long study. Dispersal may occur mainly during the rainy season. The capture-mark-recapture method was successful and the longevity of the bugs and the distances covered by nymphs and adults were recorded.

Putative panmixia in restricted populations of Trypanosoma cruzi isolated from wild Triatoma infestans in Bolivia

Trypanosoma cruzi, the causative agent of Chagas disease, is subdivided into six discrete typing units (DTUs; TcI-TcVI) of which TcI is ubiquitous and genetically highly variable. While clonality is the dominant mode of propagation, recombinant events play a significant evolutive role. Recently, foci of wild Triatoma infestans have been described in Bolivia, mainly infected by TcI. Hence, for the first time, we evaluated the level of genetic exchange within TcI natural potentially panmictic populations (single DTU, host, area and sampling time). Seventy-nine TcI stocks from wild T. infestans, belonging to six populations were characterized at eight microsatellite loci. For each population, Hardy-Weinberg equilibrium (HWE), linkage disequilibrium (LD), and presence of repeated multilocus genotypes (MLG) were analyzed by using a total of seven statistics, to test the null hypothesis of panmixia (H0). For three populations, none of the seven statistics allowed to rejecting H0; for another one the low size did not allow us to conclude, and for the two others the tests have given contradictory results. Interestingly, apparent panmixia was only observed in very restricted areas, and was not observed when grouping populations distant of only two kilometers or more. Nevertheless it is worth stressing that for the statistic tests of "HWE", in order to minimize the type I error (i. e. incorrect rejection of a true H0), we used the Bonferroni correction (BC) known to considerably increase the type II error ( i. e. failure to reject a false H0). For the other tests (LD and MLG), we did not use BC and the risk of type II error in these cases was acceptable. Thus, these results should be considered as a good indicator of the existence of panmixia in wild environment but this must be confirmed on larger samples to reduce the risk of type II error.

Wild populations of Triatoma infestans are highly connected to intra-peridomestic conspecific populations in the Bolivian Andes

Triatoma infestans, the major vector of Chagas disease south of the Amazon in South America, has a large distribution of wild populations, contrary to what has previously been stated. These populations have been suspected of being the source of reinfestation of human habitats and could impede the full success of vector control campaigns. This study examined gene flow between intra-peridomestic populations and wild populations collected in the surround areas in three Andean localities in Bolivia. The populations were defined according to temporal, ecological, and spatial criteria. After DNA extraction from the legs of each insect, the samples were analyzed using seven microsatellite markers. First, the analysis of molecular variance (AMOVA) detected an absence of differentiation between wild and intra-peridomestic populations, although strong structuring was observed between the populations within each environment. Then for some populations, the Bayesian method of assignment to inferred populations showed very similar assignment patterns of the members of wild or intra-peridomestic populations in each locality. Finally, the detection of the first-generation migrants within the different populations provided evidence of insect displacement from the wild to the intra-peridomestic environment. This result indicates that, after control campaigns in the Andes, controlling this new paradigm of vector transmission risk stemming from the invasion of human habitats by wild populations of T. infestans requires long-term maintenance of public monitoring to keep the risk at a minimal level. Since wild populations of T. infestans have also been detected elsewhere in Argentina, Paraguay, and Chile, there is an urgent need to take these populations into account in future monitoring of Chagas disease transmission.

New discoveries of sylvatic Triatoma infestans (Hemiptera: Reduviidae) throughout the Bolivian Chaco

Sylvatic populations of Triatoma infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T. infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. infestans and one T. sordida were infected with Trypanosoma cruzi TcI; one T. infestans was infected with TcII. These discoveries add to the debate on the geographic distribution of sylvatic T. infestans populations, the geographic origin of the species, and the epidemiological role of these populations.

Combination of cytochrome b heteroduplex-assay and sequencing for identification of triatomine blood meals

The identification of blood meals in vectors contributes greatly to the understanding of interactions between vectors, microorganisms and hosts. The aim of the current work was to complement the validation of cytochrome b (Cytb) heteroduplex assay (HDA) previously described, and to add the sequencing of the Cytb gene of some samples for the identification of blood meals in triatomines. Experimental feedings of reared triatomines helped to clarify the sensitivity of the HDA. Moreover, the sequencing coupled with the HDA, allowed the assessment of the technique's taxonomic level of discrimination. The primers used to produce DNA fragments of Cytb genes for HDA had a very high sensitivity for vertebrate DNAs, rather similar for mammals, birds and reptiles. However, the formation of heteroduplex depended on blood meal's quality rather than its quantity; a correlation was observed between blood meals' color and the positivity of HDA. HDA electrophoresis profiles were reproducible, and allowed the discrimination of blood origins at the species level. However, in some cases, intraspecific variability of Cytb gene generated different HDA profiles. The HDA based on comparison of electrophoresis profiles is a very useful tool for screening large samples to determine blood origins; the subsequent sequencing of PCR products of Cytb corresponding to different HDA profiles allowed the identification of species whatever the biotope in which the vectors were captured.

New insights on the Chagas disease main vector Triatoma infestans (Reduviidae, Triatominae) brought by the genetic analysis of Bolivian sylvatic populations

Triatoma infestans is the main and most widespread vector of Chagas disease in South America. For the first time, a large sample of sylvatic populations of T. infestans was analyzed by ITS-2 and mtCytB sequencing. ITS-2 showed a low level of polymorphism but revealed a dichotomy between the Andean and non-Andean sylvatic populations. On the contrary, mtCytB sequences showed a high polymorphism (19 haplotypes determined by 35 variable sites) revealing a strong structuring between most of the sylvatic populations and possible ancient isolation and bottleneck in the Northern Andes. The dichotomy Andean vs. non-Andean populations was not observed with this marker. Moreover, mtCytB haplotype genealogies showed that the non-Andean haplotypes would have derived from the Andean ones, supporting somewhat an Andean origin of the species. Nevertheless, a non-Andean origin could not be discarded because a remarkable genetic diversity was found in the non-Andean sample. The comparison of the sylvatic haplotypes with the domestic ones from GenBank suggested multiple events of T. infestans domestication in Andean and non-Andean areas, instead of a major and unique domestication event in the Bolivian Andes, as previously proposed.

A regulatory perspective on the radiological impact of NORM industries: the case of the Spanish phosphate industry

Radioactive and chemical risks coexist in NORM industries although they are usually addressed separately by regulations. The European Union (EU) has developed extensive legislation concerning both matters, which has been diversely reflected in national policies. We consider the case of the Spanish phosphate industry and analyse to which extent regulatory mandates have reduced the historical and ongoing radiological impact on the environment of phosphate facilities. Although no specific radiological constraints on effluent monitoring and release or on waste disposal have yet been imposed on NORM industries in Spain, other environmental regulations have achieved a substantial reduction on the phosphate industry impact. Nevertheless, a more efficient control could be established by eliminating the current conceptual and practical separation of chemical and radioactive risks in NORM industries. We highlight research needs to accomplish so and propose shorter-term measures that require active cooperation among the regulatory bodies involved.

First report of widespread wild populations of Triatoma infestans (Reduviidae, Triatominae) in the valleys of La Paz, Bolivia

Wild populations of Triatoma infestans, the main vector of Chagas disease in the Southern Cone countries, may be involved in reinfestation of human dwellings, limiting the success of vector-control campaigns in Bolivia. Knowledge of the distribution of these populations remains incomplete. We report here the detection of T. infestans wild populations in large areas in the department of La Paz, Bolivia. Among 18 sylvatic areas investigated, 17 were positive with T. infestans specimens. The infection rate of captured T. infestans with Trypanosoma cruzi was 85.7% in adult specimens. These results expand the geographical distribution of wild populations of T. infestans; it may be distributed throughout the Inter-Andean Dry Forest eco-region of Bolivia. The current information allows us to propose the hypothesis that a sylvatic origin of the reinfestation is located in the valleys of La Paz.

Analysis of prognostic factors in patients with adult T-cell leukemia/lymphoma

8575

Background: Adult T-cell leukemia/lymphoma (ATLL) is associated with human T-cell lymphotropic virus type-I (HTLV-1) described in Southern Japan, Europe, Caribbean and South America. Risk-stratification tools for ATLL have not been adequately evaluated. This study attempts to define prognostic factors for patients with ATLL. Methods: A total of 102 cases from our Institution were collected between January 1997 and September 2008. Diagnosis was based on clinical history and histological findings consistent with ATLL and either positive HTLV-1 serology or evidence of HTLV-1 integration. Survival curves were estimated using the Kaplan-Meier method. Univariate and multivariate analyses were evaluated using log-rank and Cox regression tests, respectively. Results: Median age was 61 years with a female:male ratio of 1.15:1. Clinical types were acute (n=45), lymphomatous (n=43), cutaneous (n=10), smoldering (n=3) and chronic (n=1). Median OS for acute, lymphomatous, smoldering and cutaneous subtype were 2, 11, 17 and 39 months, respectively (log-rank 28.5, p<0.00001). In the univariate analysis, presence of B symptoms, ECOG performance status 2, clinical stage II or higher, elevated LDH level and bone marrow (BM) involvement were independent factors for survival with p<0.05. The IPI score was available in 92 patients; 13 (14%), 12 (13%), 29 (32%) and 38 (41%) patients were low, low-intermediate, high-intermediate and high-risk, respectively. Median OS by IPI risk group was 40, 13, 6 and 2 months, respectively (p<0.005). The prognostic index for T-cell lymphoma (PIT) score was determined in 80 patients; 20 (25%), 17 (21%), 33 (41%) and 10 (13%) patients had scores of 0–1, 2, 3 and 4, respectively. Median OS by PIT risk group was 19, 5, 3 and 2 months, respectively (p<0.005). In multivariate analysis, BM involvement and elevated LDH were significant for survival. Conclusions: This retrospective series represents the largest Latin-American experience on ATLL, which is a heterogeneous disease with distinct clinical features and outcomes. The IPI ant PIT scores, used for risk-stratification of aggressive B-cell and peripheral T-cell lymphomas, respectively, appear as good prognostic indicators for ATLL as well. Further research is needed to better risk-stratify this unique lymphoma.

No significant financial relationships to disclose.

Progesterone modulation of alpha5 nAChR subunits influences anxiety-related behavior during estrus cycle

Smokers often report an anxiolytic effect of cigarettes. In addition, stress-related disorders such as anxiety, post-traumatic stress syndrome and depression are often associated with chronic nicotine use. To study the role of the alpha5 nicotinic acetylcholine receptor subunit in anxiety-related responses, control and alpha5 subunit null mice (alpha5(-/-)) were subjected to the open field activity (OFA), light-dark box (LDB) and elevated plus maze (EPM) tests. In the OFA and LDB, alpha5(-/-) behaved like wild-type controls. In the EPM, female alpha5(-/-) mice displayed an anxiolytic-like phenotype, while male alpha5(-/-) mice were undistinguishable from littermate controls. We studied the hypothalamus-pituitary-adrenal axis by measuring plasma corticosterone and hypothalamic corticotropin-releasing factor. Consistent with an anxiolytic-like phenotype, female alpha5(-/-) mice displayed lower basal corticosterone levels. To test whether gonadal steroids regulate the expression of alpha5, we treated cultured NTera 2 cells with progesterone and found that alpha5 protein levels were upregulated. In addition, brain levels of alpha5 mRNA increased upon progesterone injection into ovariectomized wild-type females. Finally, we tested anxiety levels in the EPM during the estrous cycle. The estrus phase (when progesterone levels are low) is anxiolytic-like in wild-type mice, but no cycle-dependent fluctuations in anxiety levels were found in alpha5(-/-) females. Thus, alpha5-containing neuronal nicotinic acetylcholine receptors may be mediators of anxiogenic responses, and progesterone-dependent modulation of alpha5 expression may contribute to fluctuations in anxiety levels during the ovarian cycle.

Evaluating the suitability of nicotinic acetylcholine receptor antibodies for standard immunodetection procedures

Nicotinic acetylcholine receptors play important roles in numerous cognitive processes as well as in several debilitating central nervous system (CNS) disorders. In order to fully elucidate the diverse roles of nicotinic acetylcholine receptors in CNS function and dysfunction, a detailed knowledge of their cellular and subcellular localizations is essential. To date, methods to precisely localize nicotinic acetylcholine receptors in the CNS have predominantly relied on the use of anti-receptor subunit antibodies. Although data obtained by immunohistology and immunoblotting are generally in accordance with ligand binding studies, some discrepancies remain, in particular with electrophysiological findings. In this context, nicotinic acetylcholine receptor subunit-deficient mice should be ideal tools for testing the specificity of subunit-directed antibodies. Here, we used standard protocols for immunohistochemistry and western blotting to examine the antibodies raised against the alpha3-, alpha4-, alpha7-, beta2-, and beta4-nicotinic acetylcholine receptor subunits on brain tissues of the respective knock-out mice. Unexpectedly, for each of the antibodies tested, immunoreactivity was the same in wild-type and knock-out mice. These data imply that, under commonly used conditions, these antibodies are not suited for immunolocalization. Thus, particular caution should be exerted with regards to the experimental approach used to visualize nicotinic acetylcholine receptors in the brain.

Natural ionizing radiation exposure of the Spanish population

This study investigates the exposure of the Spanish population to natural radiation sources. The annual average effective dose is estimated to be 1.6 mSv, taking into account contributions from cosmic radiation (18%), terrestrial gamma radiation (30%), radon and thoron inhalation (34%) and ingestion (18%). Cosmic radiation doses were calculated from town altitude data. Terrestrial gamma ray exposure outdoors were derived from the MARNA (natural gamma radiation map of Spain); indoor exposure was obtained multiplying the corresponding outdoor value by an experimentally calculated conversion factor. Radon doses were estimated from national surveys carried out throughout the country. To assess doses by ingestion, data from a detailed study on consumption habits in Spain and average radioactivity values from UNSCEAR have been considered. The variability in the exposures among individuals in the population has been explicitly taken into account in the assessment.

Characterization of enzootic foci of Venezuelan equine encephalitis virus in western Venezuela

The distribution of the sylvatic subtype ID Venezuelan equine encephalitis (VEE) viruses in the lowland tropical forests of western Venezuela was investigated using remote sensing and geographic information system technologies. Landsat 5 Thematic Mapper satellite imagery was used to study the reflectance patterns of VEE endemic foci and to identify other locations with similar reflectance patterns. Enzootic VEE virus variants isolated during this study are the closest genetic relatives of the epizootic viruses that emerged in western Venezuela during 1992-1993. VEE virus surveillance was conducted by exposing sentinel hamsters to mosquito bites and trapping wild vertebrates in seven forests identified and located by means of the satellite image. We isolated VEE viruses from 48 of a total of 1,363 sentinel hamsters in two of the forests on six occasions, in both dry and wet seasons. None of the 12 small vertebrates captured in 8,190 trap-nights showed signs of previous VEE virus infection. The satellite image was classified into 13 validated classes of land use/vegetation using unsupervised and supervised techniques. Data derived from the image consisted of the raw digital values of near- and mid-infrared bands 4, 5, and 7, derived Tasseled Cap indices of wetness, greenness, and brightness, and the Normalized Difference Vegetation Index. Digitized maps provided ancillary data of elevation and soil geomorphology. Image enhancement was applied using Principal Component Analysis. A digital layer of roads together with georeferenced images was used to locate the study sites. A cluster analysis using the above data revealed two main groups of dense forests separated by spectral properties, altitude, and soil geomorphology. Virus was isolated more frequently from the forest type identified on flat flood plains of main rivers rather than the forest type found on the rolling hills of the study area. The spatial analysis suggests that mosquitoes carrying the enzootic viruses would reach 82-97% of the total land area by flying only 1-3 km from forests. We hypothesize that humans within that area are at risk of severe disease caused by enzootic ID VEE viruses. By contrast, equines could actually become naturally vaccinated, thus preventing the local emergence of epizootic IC VEE virus strains and protecting humans indirectly.

Genetic diversity and relationships among Venezuelan equine encephalitis virus field isolates from Colombia and Venezuela

During field studies of enzootic Venezuelan equine encephalitis (VEE) viruses associated with epizootic emergence, a large number of virus isolates were made in sylvatic foci of Venezuela and Colombia. To rapidly characterize these isolates, antigenic subtypes were determined by means of immunofluorescence and by single-strand conformational polymorphism (SSCP) analysis by use of an 856-bp fragment from the P62 gene, which we used to distinguish genetic variants. Representative isolates were sequenced to assess the sensitivity of SSCP to detect genetic differences. The SSCP analysis distinguished isolates differing by as little as 1 nucleotide; overall, differences of > or = 1 nucleotide were recognized 89% of the time, and the sensitivity to distinguish strains that differed by only 1 or 4 nucleotides was 17 and 57%, respectively. Phylogenetic analyses of representative sequences showed that all recent isolates from the Catatumbo region of western Venezuela and the middle Magdalena Valley of Colombia were closely related to epizootic subtype IAB and IC strains; strains from Yaracuy and Miranda States were more distantly related. Cocirculation of the same virus genotype in both Colombian and Venezuelan foci indicated that these viruses are readily transported between enzootic regions separated by > 300 km. The SSCP analysis appears to be a simple, fast, and relatively efficient method of screening VEE virus isolates to identify meaningful genetic variants.

Spatial dispersion of adult mosquitoes (Diptera: Culicidae) in a sylvatic focus of Venezuelan equine encephalitis virus

We studied the spatial localization of mosquitoes in sylvatic focus of Venezuelan equine encephalitis virus in western Venezuela to identify mosquito species potentially involved in the hypothesized transport of viruses out of enzootic foci. The following criteria were used to identify species with potential for virus export: (1) common in the forest and surrounding area, (2) feeding on a wide range of vertebrates; (3) long dispersal capabilities, and (4) established vectorial competence for enzootic or epizootic VEE viruses. CDC traps baited with light/CO2 were operated for four and 12-h intervals to collect mosquitoes at four stations along two forest/open area transects from September to November 1997. We collected 60,444 mosquitoes belonging to 11 genera and 34 species. The most common species were Aedes serratus (Theobald), Ae. scapularis (Rondani), Ae. fulvus (Wiedmann), Culex nigripalus Theobald, Cx, (Culex) "sp", Cx. mollis Dyar & Knab, Cx. spissipes (Theobald), Cx. pedroi Sirivanakarn and Belkin, Psorophora ferox (Humboldt), Ps. albipes (Theobald), and Ps. cingulata (F.). Very few mosquitoes were captured during the (day in the open area outside the forest, suggesting that any virus export from the forest may occur at night. The following mosquitoes seemed to be mostly restricted to the forest habitat: Ae. serratus, Ps. ferox, Ps. albipes, sabethines, Cx. spissipes, Cx. pedroi, Cx. dunni Dyar, and Ae. fulvus. The main species implicated its potential virus export were Cx. nigripalpus, Ae. scapularis, and Mansonia titillans (Walker).

Lateral mobility and anchoring of recombinant GABAA receptors depend on subunit composition

The clustering of type A gamma-aminobutyric acid receptors (GABA(A)R) at discrete and functionally significant domains on the nerve cell surface is an important determinant in the integration of synaptic inputs. To discern the role that the subunits of the GABA(A)R play in determining the receptor's cell surface topography and mobility, the alpha1, beta1, beta3, and gamma2s subunits were transfected into COS7, HEK293, and PC12 cells and the distribution and cell surface mobility of these recombinant receptors were examined. Our results show that alpha1 subunits are retained in the endoplasmic reticulum while beta1 and beta3 subunits are sorted to the plasma membrane where they form clusters. Co-expression and co-assembly of alpha1 and beta3 subunits result in the rescue of intracellular alpha1 subunits, which are transported as alphabeta subunit complexes to the cell surface where they formed clusters. Fluorescence photobleach recovery and single particle tracking of recombinant receptors show that, despite clustering, beta3 subunit homooligomers are mobile within a cell surface domain. Inclusion of alpha1 in beta3 or beta3gamma2s complexes, however, dramatically reduces the receptor's lateral mobility in COS 7 and PC12 cells and anchors GABA(A)Rs on the cell surface, suggesting the formation of a direct link to a component of the cytoskeleton. The mobility of recombinant receptors that include the alpha1 subunit mirrors the mobility of GABA(A)Rs on cell bodies and dendrites of cortical and spinal cord neurons. The results suggest that incorporation of alpha1 subunits give rise to a population of GABA(A)Rs that are immobilized on the cell surface.

[A model for evaluating internal accuracy]

OBJECTIVE

To provide an evaluation model of internal accuracy illustrating its use in a quality control program of clinical chemistry.

METHODS

The model uses data transformed to percentage of assigned value (%AV) that allows the pooling of different controls. Precision is evaluated by the mean of the intracontrol coefficients of variation, and accuracy by the mean of means of the %VAs and its standard deviation. The model was used in 17,280 measurements of 23 analytes assayed in seven pairs of controls (medium and high concentration) during four years in two automated clinical chemistry analyzers.

RESULTS

The model established inaccuracy of 5% to 25% in seven analytes, five of them enzymes. It also detected interanalyzer differences in accuracy of five analytes (22%) and an erroneous assigned value in 19 of 304 controls (6%).

CONCLUSIONS

The model showed its capacity to dissect the sources of variation of accuracy. There was inaccuracy in 30% of the analytes but further studies are needed to validate these inaccuracies with controls of other sources. The model can be useful for control programs of any quantitative assay system. A summary description of the model's operation is given.

[Chemical composition and digestibility of the protein of 20 ecotypes of Pijiguao (Bactris gassipaes) of the Venezuelan Amazon]

Precooked flour (80 degrees C x 3 hours) from the pulp of 20 ecotypes of Pijiguao cultivated in the Amazon area of Venezuela and dried at 80 degrees C for 3 hours was manufactured for the purpose of developing an alternative method of conservation of the fruit for human consumption and for the purpose of contributing to the study of the germoplasm through the assessment of its chemical characterization by applying the AOAC methods. The results showed a wide statistical variability (p < 0.05) among the ecotypes in relation to the fat content (5.13%-17.30%), protein content (5.00%-8.30%), starch content (29.13%-56.40%), and dietetic fiber content (8.10%-21.00%). Likewise, significant differences in the carotenoid content (3.46-40.06 mg/100 g) and the vitamin C content (6.60 to 51.60 mg/100 g) were also detected. The digestibility "in vitro" of the protein was high (88.10%-91.90%). In addition color was analyzed in a tristimulus color meter and the data varied between L = 65.07 to 81.84; a = 0.18 to 13.96 y b = 18.30 to 38.82. Orange, yellow, and beige were observed Pijiguao precooked flour is a potential source of dietetic carotenoids, vitamin C, fat, and starch.

Bioavailability of diclofenac after intramuscular administration to rats with experimental spinal cord injury

Spinal cord injury (SCI) has been proposed to reduce drug bioavailability after intramuscular administration owing to an impairment in blood flow to paralyzed limbs. To test this hypothesis, we studied diclofenac bioavailability after intramuscular administration in rats with SCI. Female Sprague-Dawley rats were submitted to SCI at the T8 level by contusion and received a 10-mg/kg intramuscular diclofenac dose in the thigh of the right hind limb 24 h after injury. Blood samples were drawn, diclofenac concentration was determined by high-performance liquid chromatography, and whole-blood concentration against time curves were constructed. SCI did not result in a significant change in C(max) and T(max), compared with sham-lesioned controls, suggesting that the rate of drug absorption was not altered. Half-life was prolonged, and therefore area under the curve was greater in SCI than in sham-lesioned animals. Therefore, 24 h after SCI at the T8 level, intramuscular diclofenac bioavailability was not impaired but was actually enhanced. Results suggest that the rate of intramuscular diclofenac absorption is not significantly altered, although its elimination is impaired, during the acute phase of SCI. It then appears that SCI-induced pharmacokinetic alterations are complex, the global bioavailability depending on the sum of SCI effects on absorption, distribution, and elimination. Systematic studies on SCI-induced alterations are thus required to provide information leading to a rational dosing regimen design for SCI patients.

Dengue virus structural differences that correlate with pathogenesis

The understanding of dengue virus pathogenesis has been hampered by the lack of in vitro and in vivo models of disease. The study of viral factors involved in the production of severe dengue, dengue hemorrhagic fever (DHF), versus the more common dengue fever (DF), have been limited to indirect clinical and epidemiologic associations. In an effort to identify viral determinants of DHF, we have developed a method for comparing dengue type 2 genomes (reverse transcriptase PCR in six fragments) directly from patient plasma. Samples for comparison were selected from two previously described dengue type 2 genotypes which had been shown to be the cause of DF or DHF. When full genome sequences of 11 dengue viruses were analyzed, several structural differences were seen consistently between those associated with DF only and those with the potential to cause DHF: a total of six encoded amino acid charge differences were seen in the prM, E, NS4b, and NS5 genes, while sequence differences observed within the 5' nontranslated region (NTR) and 3' NTR were predicted to change RNA secondary structures. We hypothesize that the primary determinants of DHF reside in (i) amino acid 390 of the E protein, which purportedly alters virion binding to host cells; (ii) in the downstream loop (nucleotides 68 to 80) of the 5' NTR, which may be involved in translation initiation; and (iii) in the upstream 300 nucleotides of the 3' NTR, which may regulate viral replication via the formation of replicative intermediates. The significance of four amino acid differences in the nonstructural proteins NS4b and NS5, a presumed transport protein and the viral RNA polymerase, respectively, remains unknown. This new approach to the study of dengue virus genome differences should better reflect the true composition of viral RNA populations in the natural host and permit their association with pathogenesis.

Genetic and phenotypic changes accompanying the emergence of epizootic subtype IC Venezuelan equine encephalitis viruses from an enzootic subtype ID progenitor

Recent studies have indicated that epizootic Venezuelan equine encephalitis (VEE) viruses can evolve from enzootic, subtype ID strains that circulate continuously in lowland tropical forests (A. M. Powers, M. S. Oberste, A. C. Brault, R. Rico-Hesse, S. M. Schmura, J. F. Smith, W. Kang, W. P. Sweeney, and S. C. Weaver, J. Virol. 71:6697-6705, 1997). To identify mutations associated with the phenotypic changes leading to epizootics, we sequenced the entire genomes of two subtype IC epizootic VEE virus strains isolated during a 1992-1993 Venezuelan outbreak and four sympatric, subtype ID enzootic strains closely related to the predicted epizootic progenitor. Analysis by maximum-parsimony phylogenetic methods revealed 25 nucleotide differences which were predicted to have accompanied the 1992 epizootic emergence; 7 of these encoded amino acid changes in the nsP1, nsP3, capsid, and E2 envelope glycoprotein, and 2 were mutations in the 3' untranslated genome region. Comparisons with the genomic sequences of IAB and other IC epizootic VEE virus strains revealed that only one of the seven amino acid changes associated with the 1992 emergence, a threonine-to-methionine change at position 360 of the nsP3 protein, accompanied another VEE virus emergence event. Two changes in the E2 envelope glycoprotein region believed to include the major antigenic determinants, both involving replacement of uncharged residues with arginine, are also candidates for epizootic determinants.

Origins of horizontal cell spectral responses in the retina of marine teleosts (Centropomus and Mugil sp)

Intracellular recording and marking of horizontal cells (HCs) were carried out in isolated retinas of marine teleosts (Centropomus and Mugil sp.) to identify the cellular origins of different spectral types of S-potential. The spectral responses recorded under mesopic conditions were classified into four types: photopic L, biphasic C(R/G), biphasic C(G/R), and scotopic L(sL). Intracellular marking with Lucifer yellow (LY) or Procion yellow (PY) revealed that in the Centropomus retina an L-type response was recorded from H1 and H2 cells, C(R/G)-type from H3 cells, and sL-type from H4 cells. However, in 20% of microelectrode penetrations from the photoreceptor surface, the sequential order of response appearances was found to be L-, sL-, and C(R/G)-types. In this species, thick dendritic processes of H3 and H4 cells are distributed at the same level as the cell body. In the Mugil retina, on the other hand, L-type response was recorded from H1 cells, C(G/R)-type from H2 cells, C(R/G)-type from H3 cells, and sL-type from H4 cells, this sequential arrangement being very regular. In both species, the cone-connected H1 cells are small and possess an axon, while the two other cone HCs as well as rod-connected H4 cells are axonless. Earlier (Negishi et al., 1988) and present findings indicate that there is a wide variety of HC morphology and functional organization in the teleost retina.