Suicide and serotonin: study of variation at seven serotonin receptor genes in suicide completers

Suicide is an important public health problem, accounting for a significant proportion of total mortality among young people, particularly males. There is growing and consistent evidence suggesting that genetic factors play an important role in the predisposition to suicide. Based on several lines of evidence supporting a reduced serotonergic neurotransmission in subjects who committed suicide, we investigated variation at genes that code for serotonin receptor 1B (5-HTR1B), 1Dalpha (5-HTR1Dalpha), 1E (5-HTR1E), 1F (5-HTR1F), 2C (5-HTR2C), 5A (5-HTR5A), and 6 (5-HTR6) in a total sample of 106 suicide completers and 120 normal controls. No differences were observed in allelic or genotypic distributions between groups for any of the loci investigated. Moreover, further analysis according to suicide method or psychopathology also failed to reveal differences between groups. Our results do not support a substantial role of these serotonergic receptors in suicide completion.

Evidence for a genetic association between monoamine oxidase A and restless legs syndrome

BACKGROUND

Impairment in the central dopaminergic system has been consistently suggested as an etiologic factor in restless legs syndrome (RLS).

OBJECTIVE

To investigate a possible role for the MAOA and MAOB genes in RLS using a population-based association study.

METHODS

In addition to a dinucleotide repeat located within the second intron of the MAOB gene, a functional variable number of tandem repeat (VNTR) polymorphism recently identified in the MAOA gene promoter region was examined, using 96 extensively characterized patients and 200 control subjects matched for ethnic background. The relationship between variation at these loci and several clinical features was also considered.

RESULTS

Pertaining to the MAOA gene, females with the high activity allele had a greater risk (OR: 2.0; 95% CI: 1.06 to 3.77) of being affected with RLS than females carrying the low activity alleles. The authors did not observe this association among the male subjects (OR: 0.98; 95% CI: 0.31 to 3.14). Interestingly, females carrying the high transcription alleles showed a longer sleep onset latency (U = 163.5; p = 0.015) and exhibited a higher movement index during the Suggested Immobilization Test (Student's t-test = -2.02; p = 0.048). No differences were observed regarding the MAOB gene in our sample.

CONCLUSIONS

The high activity allele of the MAOA gene may represent a modifying factor involved in the severity of RLS manifestations in females.

Genetic diversity among isolates of Trichinella spiralis from the Province of Buenos Aires, Argentina

Random Amplified Polymorphic DNAs, (RAPDs) are used to study the occurrence of Trichinella britovi and T5 among domestic animals in the Province of Buenos Aires, Argentina and to assess the genetic diversity among isolates of T. spiralisfrom this area in a number of infected hosts. All the local isolates proved to be T. spiralis. Six of the eight primers used indicate that the Buenos Aires isolates are distinct from each other as they produce a considerable number of polymorphic bands. Our overall estimates are relatively higher than other intraspecific distances previously estimated within species of this genus and among T. spiralis isolates. Such high degrees of variability observed among local isolates and between isolates from Buenos Aires and Spain should be taken into account when defining isolates within this species, and considering differences in the epidemiology of T. spiralis.

Apparent dopamine D1 and D2 receptors in the weaver mutant mouse: receptor binding and coupling to adenylyl cyclase

Weaver mutant mice have a selective degeneration of the nigrostriatal dopamine pathway arising between 7-21 days after birth. The goal of this study was to investigate the effects of this mutation on different parameters of the nigrostriatal and mesolimbic dopamine system: apparent D1 and D2 receptor binding sites as well as their signal transduction pathway. Using quantitative autoradiography of ligands for dopamine D1, D2 receptors and the dopamine uptake site, we found a significant loss in apparent D1 receptor binding sites throughout the neostriatum, significant increase of apparent D2 receptor binding in the dorsal aspect of the neostriatum, and almost complete loss of DA uptake sites in these regions of the weaver mouse. In contrast to the neostriatum, the density of dopamine receptors and uptake sites in the nucleus accumbens of the weaver mouse did not differ from controls. Despite alterations in the binding of apparent D1 and D2 receptors, there was no significant difference in either basal, DA stimulated or GTPgammaS stimulated cAMP production. These findings suggest the down-regulation of apparent D1 receptor binding sites reported in this model, probably does not reflect an important physiological mechanism through which these animals compensate for loss of dopamine innervation.

[The influence of therapy (sympathomimetic amines versus vasodilators) in the indexes of ejection fraction derived from an analysis of Doppler aortic flow]

PURPOSE

To assess the influence of inotropic IV therapy--dobutamine and/or dopamine--versus vasodilator therapy--nitroprusside, captopril or hydralazine--in aortic flow ejection phase indexes obtained by pulsed Doppler echocardiography.

METHODS

In 17 patients admitted to the ICU (11 males, 62 +/- 14 years, 9 with ischemic cardiomyopathy and 8 with dilated cardiomyopathy, all in sinus rhythm), with congestive heart failure, and submitted to tailored therapy, 53 serial pulsed Doppler and hemodynamic evaluations were made as the therapy changed the hemodynamic and clinical status. Considering serial consecutive evaluations, a hemodynamic improvement was obtained only with inotropics in 13 (group A), and with vasodilators in only 15 (group B). The following ejection phase indexes were calculated from Doppler registers: average acceleration (AvAc) and ejection force (EFor), calculated according to the formula: Efor = 1.06 x Aortic Orifice Area x AvAc x Acceleration Velocity Time Integral.

RESULTS

Arterial blood pressure increased in gr A (76.2 +/- 14.1 to 81.4 +/- 14.8 mm Hg, p < 0.05) and decreased in gr B (85.1 +/- 12.6 to 76.2 +/- 9.7 mm Hg (p < 0.05). In both groups there was a significant (p < 0.05) increase in cardiac output (CO)-from 3.9 +/- 1.1 to 4.9 +/- 1.4 L/min in group A, and from 3.9 +/- 1.2 to 4.4 +/- 1.2 L/min in group B. CO increased 18.7% in group A and 13.8% in group B (NS). There was a decrease in pulmonary capillary wedge pressure (PCWP) from 19.5 +/- 6.0 to 15.1 +/- 5.8 mm Hg in group A (p < 0.05), and from (16.9 +/- 5.7 to 12.1 +/- 4.6 mm Hg in group B (p < 0.05). PCWP decreased 19.7% in group A and 27.8% in group B (NS). Systemic vascular resistance (SVR) changed from 18.2 +/- 7.0 to 16.2 +/- 7.1 Wood U in group A (p < 0.05), and from 22.3 +/- 9.3 to 17.7 +/- 5.7 Wood U in group B (p < 0.05). In group A, AvAc increased-from 1347 +/- 611 cm.s-2 (p < 0.05), as did Efor-from 15.4 +/- 10.7 to 20.2 +/- 11.0 g.cm,s-2 (p < 0.05), whereas in group B there was no significant change in either AvAc-from 1337 +/- 284 to 1277 +/- 256 cm.s-2, or Efor-from 22.7 +/- 17.0 to 23.8 +/- 15.0 g.cm.s-2.

CONCLUSIONS

Vasodilator therapy, although inducing hemodynamic changes similar to inotropics, does not alter the ejection phase indexes. Therefore, AvAc and Efor, in spite of being calculated from the aortic flow, are independent of the changes in PCWP and SVR and seem to reflect changes in inotropism in the clinical setting.

Cation disorder in ferroelectric PbBi2Nb2O9

The ferroelectric Curie temperature, Tc , of PbBi2Nb2O9 was found to shift from 833 K in samples slowly cooled from 1373 K to Tc 's up to 883 K when the samples were quenched from various temperatures in the range 973–1373 K. The variation of Tc with heat treatment was fully reversible. Extra Raman modes appear and the width of some Raman bands change as a function of heat treatment. These results are interpreted in terms of cation order–disorder involving the Pb2+ and Bi3+ ions in the perovskite units and the Bi2O2 layer. Neutron Rietveld analyses of the structures (orthorhombic, A21 am, Z = 4, λ = 1.216) indicate a possible change in cationic order–disorder, with Pb2+ ions preferentially occupying the perovskite A-sites to the extent of 91 (7) and 80 (7)%, respectively, in the quenched and slowly cooled samples.

[The QTc interval and its dispersion in hypertrophic myocardiopathy--its relation to complex ventricular arrhythmias and the effect of anti-arrhythmia agents]

The aim of the present study was to evaluate, in patients with hypertrophic cardiomyopathy (HCM): 1. The relation of rate corrected QT interval (QTc) and of QTc interlead variability (QTc dispersion) to complex ventricular arrhythmias (CVA); 2. The effects of amiodarone (Am), beta-blockers (beta B) and calcium antagonists (CA) on QTc and on QTc dispersion. Surface 12 leads ECG was analysed in 55 patients with HCM (39 +/- 12 years, 32 males). All patients were in sinus rhythm, without bundle branch block. Maximum (max), minimum (min) and mean QTc values were considered. QTc dispersion was calculated as: a) max QTc - min QTc (max-min); b) dispersion index (DI) = standard deviation of QTc/mean QTcx100. Patients groups were defined accordingly to: 1--the absence (group A1-35 patients) or the presence (group A2-20 patients) of CVA on 24 hours Holter monitoring; II--absence of cardioactive medication (group B1-20 patients) versus monotherapy with Am (group B3-10 patients), or beta B (group B4-15 patients), or CA (group B5-10 patients). Age, gender, type of HCM (asymmetric versus concentric) and echocardiographic fractional shortening were not different in the studied groups.

RESULTS

[table: see text]

CONCLUSIONS

1. Maximum QTc interlead QTc dispersion are increased in patients with HCM that show CVA on Holter monitoring; 2. Amiodarone prolongs QTc but reduces QTc dispersion, while beta-blockers and calcium antagonists do not significantly change neither the duration nor the dispersion of ventricular repolarization.

Molecular characterization of the variable regions of a mouse polyreactive IgG2b antibody with rheumatoid factor activity

The complete nucleotide sequences of heavy and light chains of a mouse polyreactive IgG2b antibody were determined. This antibody, obtained after primary immunization of BALB/c mice with human lymphoblastoid cells, possess anti-HLA-DR and anti-rheumatoid factor activities and reacts with various self and nonself antigens. The VL and VH segments were found to belong to the VK8 and VH7183 families, respectively. The VH segment shared a high percentage of sequence similarity (95%) with previously described germline genes. The VK segment had 98.9% of sequence similarity with a consensus sequence VK8 of antibodies with anti-phosphorylcholine activity. Furthermore, the framework regions 2 and 3 of the VL segment were very similar to the framework regions 2 and 3 of other antibodies known to possess rheumatoid factor activity. We postulate that during immunization, the presence of HLA-DR antigens selects precursors having configurations similar to that of the germline, and induces some somatic mutations that do not significantly affect antibody polyreactivity.

Multiple small-angle scattering from a statistical medium

A generalized formalism on multiple small-angle scattering is proposed to investigate the nature of the extractable structural information on inhomogeneities from the multiple-scattering profile. It is found that the statistical nature of the medium can broaden as well as narrow the scattering profile depending upon the characteristics of the medium. The nature and the extent of the effect of the various approximations on analysing the multiple-scattering data are discussed.

Characterization of a murine immunoglobulin VH gene segment in subgroup III: a new member of the 7183 gene family

A new gene for the variable region of the immunoglobulin heavy chain (VH gene) has been isolated from BALB/c adult liver DNA using a cDNA plasmid probe containing a mouse VH sequence. The complete nucleotide sequence of this germline gene (VH10-19), shows that it belongs to the 7183 gene family. The VH gene appears to contain an intervening 104-base-long sequence and displays the same recombination signal sequences that those observed in the germline 81X. The presence of an internal heptamer at the 3' end of the VH10-19 coding region let an alternative recombination event that could increase the representation of this gene in the immature repertoire.