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PubMedDate not supplied

Comparison of the neuromuscular systems among actinotroch larvae: systematic and evolutionary implications.

A comparative analysis of the larval and presumptive juvenile neuromuscular systems among actinotroch larvae was performed using confocal laser microscopy with probes for F-actin and serotonin. Currently, there are two main categories of larval nervous systems based on the origin of the nerve fibers that innervate the larval tentacles. Characteristics of the serotonergic cells of the larval apical ganglion and juvenile nervous system have remained relatively conserved, but the structure of the secondary (hood) sense organ and the juvenile tentacles has diversified among species. Differences in larval musculature are mainly associated with differences in hood morphology. The presumptive, juvenile neuromuscular system is either integrated or separated from that of the larva based on the origin of the juvenile tentacles. Among species, the juvenile tentacles are made by remodeling the larval tentacles, developed from a basal tentacular thickening, or developed as a completely separate set in the larva. Differentiation of the neuromuscular structures of the juvenile tentacles is more diverse than their outward morphological characteristics would suggest. Importance of these larval characters is discussed in terms of current problems that exist within phoronid systematics. Evolutionary implications of these morphological characters are discussed among the phoronids, brachiopods, and related bilaterians. Overall, the integration or separation of larval and juvenile neuromuscular characters may yield insights into the evolution of lophotrochozoan body plans.

Animals↗

PubMed2000

A prospective naturalistic study of 326 panic-agoraphobic patients treated with antidepressants.

OBJECTIVE: How far the results of randomized controlled studies apply to everyday care cannot be judged without regular measurements of outcomes in daily practice. We report on systematic data from a 3-year naturalistic prospective study on panic disorder-agoraphobic (PDA) patients treated with antidepressants in a setting of routine clinical practice. Our aim is to describe the evolution of PDA in relation to the treatments employed, and to explore demographic and clinical characteristics that might be predictive of outcome. METHODS: 326 DSM-III-R PDA patients treated with antidepressants in a setting of routine clinical practice were included in a 3-year naturalistic prospective study. We utilized structured and semi-structures instruments, including the Structured Clinical Interview for Diagnosis and the Longitudinal Interview Follow-up Examination. The main antidepressants used were imipramine (39%), clomipramine (28.5%) and paroxetine (23.3%); only 9% of patients received other antidepressants. RESULTS: 147 patients (45.1%) stayed on medication throughout the entire period of the follow-up. Of those who interrupted the treatment, 38% stayed in remission. The probability of achieving at least one remission during the 3-year follow-up period was 96.5% for PD and 95.9% for Agoraphobia. Relapses after a period of at least 2 months of complete remission were also common, and the probability of presenting at least one relapse during the 3-years follow-up period was 67.1% for PD and 39% for Agoraphobia. The longest period of remission of PD is associated with low severity, medium-lasting course in patients with an onset of the illness in young adulthood. Less severe agoraphobia associated with moderately severe panic attacks appears to confer a better control of phobic behavior. All three major drugs were reasonably well tolerated (only 9% dropped out because of side effects), with sexual dysfunction and increased appetite being the most common side effects at the last evaluation; in the first phase of the treatment anticholinergic effects and jitteriness were more common with TCAs. CONCLUSION: Both classical antidepressants and paroxetine emerge as a useful treatment in the long-term management of PDA; paroxetine appears particularly useful in PDA patients because it was significantly less likely to induce jitteriness, thereby reducing barriers to compliance.

Adult↗

PubMed2005

Temporal characterization of the neural correlates of perceptual decision making in the human brain.

Single and multi-unit recordings in primates have identified spatially localized neuronal activity correlating with an animal's behavioral performance. Due to the invasive nature of these experiments, it has been difficult to identify such correlates in humans. We report the first non-invasive neural measurements of perceptual decision making, via single-trial EEG analysis, that lead to neurometric functions predictive of psychophysical performance for a face versus car categorization task. We identified two major discriminating components. The earliest correlating with psychophysical performance was consistent with the well-known face-selective N170. The second component, which was a better match to the psychometric function, did not occur until at least 130 ms later. As evidence for faces versus cars decreased, onset of the later, but not the earlier, component systematically shifted forward in time. In addition, a choice probability analysis indicated strong correlation between the neural responses of the later component and our subjects' behavioral judgements. These findings demonstrate a temporal evolution of component activity indicative of an evidence accumulation process which begins after early visual perception and has a processing time that depends on the strength of the evidence.

Adult↗

PubMed1987

Intraspecific DNA divergence in Drosophila: a study on parthenogenetic D. mercatorum.

Drosophila mercatorum is a species that can give rise to totally homozygous parthenogenetic strains. Using the technique of DNA-DNA hybridization, we have assessed the overall single-copy DNA differences among three independently derived strains that represent three independent genomes. Among strains, the average difference between homoduplex and heteroduplex median melting temperatures is 1.3 degrees C. This represents greater than or equal to 1.3% base-pair mismatch. Normalized percent of reassociation indicates further genetic differences, probably reflecting insertion/deletion differences and/or regions of the genome that are highly variable. This overall intraspecific genetic variation is higher than generally is thought to exist but is consistent with growing evidence of extensive DNA diversity within species of invertebrates. High intraspecific DNA variation may be correlated with rapid phyletic rates of evolution. Because of this high level of variation, the technique of DNA-DNA hybridization may be used to study intraspecific variation in invertebrates but is limited in its usefulness for higher systematic studies.

Animals↗

PubMed2005

Dielectric spectroscopy of aerosil-dispersed liquid crystal embedded in Anopore membranes.

The complex dielectric permittivity epsilon* values are presented for aerosil-dispersed 4-pentyl-4-cyanobiphenyl (5CB) confined in Anopore membranes. The dielectric permittivities are measured in the frequency range from 10(-2) Hz to 1 GHz at temperatures ranging from 50 degrees C down to -20 degrees C. In bulk 5CB, which has only a nematic phase, there exist two main relaxation processes: one due to the rotation of molecules around their short axes for parallel orientation of the director to the probing field and another fast relaxation process due to the librational motion of molecules for perpendicular orientation. Inside Anopore membranes both these main relaxation processes can be observed, but with subtle differences. The relaxation process due to the rotation of molecules around the short axis is faster in Anopores at all temperatures in comparison with the bulk process. Hydrophilic aerosil particles, when dispersed in the liquid-crystal (LC) phase, attach to each other via hydrogen bonds and form a three-dimensional interconnecting aerosil network, thus dividing the LC phase into small domains. Dispersing 5CB with different concentrations of hydrophilic aerosils leads to a decrease in relaxation time with aerosil concentration. In these dispersed systems a slow additional relaxation process emerges. This slow process becomes stronger with higher concentrations of aerosil. From our experiments we conclude that this process is the relaxation of 5CB molecules homeotropically aligned to the surface of the aerosil particles. In the case of 5CB-aerosil dispersions enclosed in Anopore membranes this slow process still exists and increases also with aerosil concentration. The relaxation time of the rotation of the 5CB molecules around their short axis systematically increases in these 5CB-aerosil samples in Anopore membranes with aerosil concentration from the 5CB-Anopore behavior towards the behavior observed for 5CB-aerosil dispersions. We explain the evolution as resulting from opposing tendencies from size effects (in the Anopore membranes) and disorder effects (in the aerosil dispersions).

Journal Article↗

PubMed2006

Spectral statistics in noninteracting many-particle systems.

It is widely accepted that the statistical properties of energy level spectra provide an essential characterization of quantum chaos. Indeed, the spectral fluctuations of many different systems like quantum billiards, atoms, or atomic nuclei have been studied. However, noninteracting many-body systems have received little attention, since it is assumed that they must exhibit Poisson-like fluctuations. Apart from a heuristic argument of Bloch, there are neither systematic numerical calculations nor a rigorous derivation of this fact. Here we present a rigorous study of the spectral fluctuations of noninteracting identical particles moving freely in a mean field emphasizing the evolution with the number of particles N as well as with the energy. Our results are conclusive. For N > or =2 the spectra of these systems exhibit Poisson fluctuations provided that we consider sufficiently high excitation energies. Nevertheless, when the mean field is chaotic there exists a critical energy scale L(c); beyond this scale, the fluctuations deviate from the Poisson statistics as a reminiscence of the statistical properties of the mean field.

Journal Article↗

PubMed2005

Ferroelectricity and tetragonality in ultrathin PbTiO3 films.

The evolution of tetragonality with thickness has been probed in epitaxial c-axis oriented PbTiO3 films with thicknesses ranging from 500 down to 24 A. High resolution x ray pointed out a systematic decrease of the c-axis lattice parameter with decreasing film thickness below 200 A. Using a first-principles model Hamiltonian approach, the decrease in tetragonality is related to a reduction of the polarization attributed to the presence of a residual unscreened depolarizing field. It is shown that films below 50 A display a significantly reduced polarization but still remain ferroelectric.

Journal Article↗

PubMed2004

Perilesional vs. lesional skin changes in senile lentigo.

BACKGROUND: Senile lentigo (SL) is a common component of photoaged skin. It is characterized by hyperpigmented macules which affect chronically irradiated skin mostly after 50 years of age. This study was undertaken to assess the basic morphology of SL on dorsum of hands. METHODS: A systematic comparison between lesional vs. perilesional skin using immunohistochemistry and electron microscopy was done to detect precursor lesions of SL and to determine whether melanocytes or keratinocytes were first affected in the evolution of lesions. RESULTS: In 12 cases studied, the main findings show that clusters of perilesional keratinocytes accumulate melanin in large melanosomial complexes, and that melanocytes counts are increased respective to total length of section in lesional skin, but the increment is probably due to the development of characteristic epidermal rete ridges. Melanocytes had overall a normal ultrastructure, with mostly quiescent features in perilesional skin and melanosomial transport seeming more active in lesional skin. CONCLUSIONS: Our data indicate that SL may represent a loss of epidermal melanin unit homeostasis due to chronic irradiation, where keratinocytic changes predominate over melanocytic changes. We hypothesize that abnormal pigment retention in keratinocytes is the primary defect in SL, which may partly explain the therapeutic effect of retinoids.

Aged↗

PubMedDate not supplied

State and community-based efforts to foster interoperability.

The MidSouth eHealth Alliance is developing a comprehensive health information infrastructure supporting providers in three Tennessee counties. Success in the alliance's first year is the result of sustained leadership, a systematic assessment of regional needs and capabilities, a flexible technical architecture, and a critical review of best practices from four different data exchange models already operating in other states. Long-term evolution to a truly interoperable health information infrastructure will depend on the extent to which the alliance demonstrates value to consumers and practitioners.

Community Networks↗

PubMed1999

[Acute psychosis in Réunion Island. Retrospective study performed on the 4th sector of psychiatry (west region) on the year 1997].

A retrospective study in the West psychiatry service in Reunion island (an area with 85,000 inhabitants) includes 19 files for patients hospitalized for the first time during the year 1997 with a diagnosis of acute psychosis. It excludes the troubles linked to the acute or chronic use of alcohol and the mental aberrations. This study regroups a young population, basically male and more often disadvantaged. The deliriums are stereotyped, essentially borrowed from the local culture. Two important points become visible: in more then half of the cases, drug taking (polyintoxication systematically associating cannabis) is evoked as the main etiologic factor. The prognosis in the short term of those acute psychosis is good, with a rapid regression of symptomatology under neuroleptic treatment. The evolution in the long term must be more moderated: four patients will develop a chronic psychosis; whatever the situation (taking drug or not), this acute psychotic episodes are revealing of an underlying chronic psychosis in nine cases out of nineteen. This fact underlines the interest of following those patients regularly to obtain a withdrawal with the addicted persons (risk of acute psychotic relapse) and of anticipating a chronic psychotic evolution.

Acute Disease↗

PubMed2000

Qualitative methods add quality to cardiovascular science.

Qualitative research methods are systematic approaches to knowledge development that do not involve quantification. Such methods are used widely in nursing to understand the lived experience and the socioeconomic contexts of cardiovascular health and illness. The evolution of qualitative methods through three phases - traditional, modern and postmodern - frames the discussion. Three common qualitative methods - ethnography, phenomenology and grounded theory - are presented. Applications of qualitative methods have contributed to an understanding of such phenoma as adjustment after myocardial infarction, the experience of an acute cardiac event, the experience of chronic heart disease, the family and the cardiac illness experience, family adjustment to heart transplantation, physical activity practices of working women and family influence on individual health-related decisions in response to heart health intiatives. Postmodern approaches are briefly discussed. Participatory research is presented as an example of a postmodern approach to knowledge development. It is posited that interdisciplinary and multimethod cardiovascular research programs that incorporate qualitative methods will strengthen knowledge development in the cardiovascular field by contributing to an understanding of complex issues related to cardiovascular health and illness for individual persons, families, communities and populations, and to program and policy development.

Cardiology↗

PubMedDate not supplied

[Topical problems of rabies: natural foci, the methods of study and control in Central Russia].

This analytical review is dealing with the origin and evolution of modern rabies as well as hypotheses concerning the natural foci of rabies infection, the formation of the Central European nosological area of rabies and its eastward shift due to the systematic oral vaccination of the main hosts. The epizootological problems connected with the character of the natural foci of rabies, as well as the methods and prospects of the vaccination of foxes on the territory of Central Russia, are discussed.

Administration, Oral↗

PubMed2004

[Preliminary study of the association of tuberculosis and pregnancy: about 9 cases].

From June 1668 to June 2002, we have studied at the Pneumology Clinic of Fann Hospital, pulmonary tuberculosis among 9 pregnant women. The average age was 26 years old and the consultation's delay was 5 months. All our patients had a productive cough and an evening fever coupled with a thoracic pain and a deterioration of the general condition in 7 patients (77.7%). The dyspnea and the heamoptisis were a consultation motive for 44.4% and 33.3% of the patients. The evolution of pregnancies was 29 weeks. They had all benefited from the intradermal reaction with tuberculin (IDRT) with an average diameter of 11.7 mm; it was negative in one patient. The bacilloscopy systematically done was negative in 2 patients. At the front thoracic radiography, we have found basal lesions unilateral in more than half of the cases and excavated in 44.4% of cases. They benefited from an antitubercular treatment (Rifampicine (R) + Isoniazide (H) + Pyrazinamide (Z) with a good clinical, biological, bacteriological and radiological progression. From the obstetrical point of view, there was an abortion after 5 months, 2 premature deliveries between the 7th and the 8th month and 6 normal deliveries at 9 months. Babies born from bacillary mothers systematically received an antitubercular treatment with breast feeding. In conclusion, pregnant women with pulmonary tuberculosis essentially pose a therapeutic problem, requiring a good collaboration between the lung specialist, the gyneco-obstetrician and the pediatrician. It could be more hazardous not to act early in treating a pregnant women with pulmonary tuberculosis.

Adult↗

PubMed2006

Molecular organization of 5S rDNAs in Rajidae (Chondrichthyes): Structural features and evolution of piscine 5S rRNA genes and nontranscribed intergenic spacers.

The genomic and gene organisation of 5S rDNA clusters have been extensively characterized in bony fish and eukaryotes, providing general issues for understanding the molecular evolution of this multigene DNA family. By contrast, the 5S rDNA features have been rarely investigated in cartilaginous fish (only three species). Here, we provide evidence for a dual 5S rDNA gene system in the Rajidae by sequence analysis of the coding region (5S) and adjacent nontranscribed spacer (NTS) in five Mediterranean species of rays (Rajidae), and in a large number of piscine taxa including lampreys and bony fish. As documented in several bony fish, two functional 5S rDNA types were found here also in the rajid genome: a short one (I) and a long one (II), distinguished by distinct 5S and NTS sequences. That the ancestral piscine genome had these two 5S rDNA loci might be argued from the occurrence of homologous dual gene systems that exist in several fish taxa and from 5S phylogenetic relationships. An extensive analysis of NTS-II sequences of Rajidae and Dasyatidae revealed the occurrence of large simple sequence repeat (SSR) regions that are formed by microsatellite arrays. The localization and organization of SSR within the NTS-II are conserved in Rajiformes since the Upper Cretaceous. The direct correlation between the SSRs extension and the NTS length indicated that they might play a role in the maintenance of the larger 5S rDNA clusters in rays. The phylogenetic analysis indicated that NTS-II is a valuable systematic tool limited to distantly related taxa of Rajiformes.

Animals↗

PubMed1987

On the overdispersed molecular clock.

Rates of molecular evolution at some loci are more irregular than described by simple Poisson processes. Three situations under which molecular evolution would not follow simple Poisson processes are reevaluated from the viewpoint of the neutrality hypothesis: concomitant or multiple substitutions in a gene, fluctuating substitution rates in time caused by coupled effects of deleterious mutations and bottlenecks, and changes in the degree of selective constraints against a gene (neutral space) caused by successive substitutions. The common underlying assumption that these causes are lineage nonspecific excludes the case where mutation rates themselves change systematically among lineages or taxonomic groups, and severely limits the extent of variation in the number of substitutions among lineages. Even under this stringent condition, however, the third hypothesis, the fluctuating neutral space model, can generate fairly large variation. This is described by a time-dependent renewal process, which does not exhibit any episodic nature of molecular evolution. It is argued that the observed elevated variances in the number of nucleotide or amino acid substitutions do not immediately call for positive Darwinian selection in molecular evolution.

Animals↗

PubMed2006

Microsatellite polymorphism across the M. tuberculosis and M. bovis genomes: implications on genome evolution and plasticity.

BACKGROUND: Microsatellites are the tandem repeats of nucleotide motifs of size 1-6 bp observed in all known genomes. These repeats show length polymorphism characterized by either insertion or deletion (indels) of the repeat units, which in and around the coding regions affect transcription and translation of genes. RESULTS: Systematic comparison of all the equivalent microsatellites in the coding regions of the three mycobacterial genomes, viz. Mycobacterium tuberculosis H37Rv, Mycobacterium tuberculosis CDC1551 and Mycobacterium bovis, revealed for the first time the presence of several polymorphic microsatellites. The coding regions affected by frame-shifts owing to microsatellite indels have undergone changes indicative of gene fission/fusion, premature termination and length variation. Interestingly, the genes affected by frame-shift mutations code for membrane proteins, transporters, PPE, PE_PGRS, cell-wall synthesis proteins and hypothetical proteins. CONCLUSION: This study has revealed the role of microsatellite indel mutations in imparting novel functions and a certain degree of plasticity to the mycobacterial genomes. There seems to be some correlation between microsatellite polymorphism and the variations in virulence, host-pathogen interactions mediated by surface antigen variations, and adaptation of the pathogens. Several of the polymorphic microsatellites reported in this study can be tested for their polymorphic nature by screening clinical isolates and various mycobacterial strains, for establishing correlations between microsatellite polymorphism and the phenotypic variations among these pathogens.

Bacterial Proteins↗

PubMed2000

Batrachology of Japan and adjacent regions - a systematic review.

As is the case with most other organisms, studies of amphibians started with systematics as the basis for many other biological fields, but systematics itself has endured a slower progress than other fields of biology have enjoyed for a long time. Nevertheless, philosophical and methodological 'revolutions' in the past 30 years, combined with more recent progress in biochemical and molecular techniques, have been forcing current systematics into a great change. Stejneger's (1907) monumental book, the first thorough review of amphibians from Japan and adjacent regions, was published nearly a century ago, and since then, the increase in number of areas that have been closely surveyed, together with the application of new theories and methods, have greatly enlarged our knowledge of the amphibian fauna in this region. For example, extensive experiments by the Hiroshima School using artificial hybridization techniques greatly contributed to our understandings of relationships among some groups of amphibians that had been taxonomically confusing. In addition to this, new species discovered by more detailed field surveys in a wider area and cryptic species revealed by analyses of isozymes and acoustic properties have made for a great increment in the number of taxa in this region. Further, analyses of DNA sequences now enable us to infer the affinities of taxa with few phylogenetically informative phenotypic properties, and the resultant phylogenetic hypotheses further contribute to our understandings of biogeography and many other issues on amphibian evolution. From these advances, it has been clarified that the amphibian species diversity is far greater than was previously expected, which in turn means a high endemism within particular regions. It is expected that future studies will also reveal exact systematic relationships of wide-ranging species, both those occurring within this region and those extending outside of it. For that purpose, international and interdisciplinary studies are indispensable. But what is also necessary is to conserve amphibian populations so that they will not disappear before their true relationships are realized. Knowledge of systematics among young amphibian biologists is also a matter of high priority.

Amphibians↗

PubMed2003

Evolutionary experimentation through hybridization under laboratory condition in Drosophila: evidence for recombinational speciation.

BACKGROUND: Drosophila nasuta nasuta (2n = 8) and Drosophila nasuta albomicans (2n = 6) are a pair of sibling allopatric chromosomal cross-fertile races of the nasuta subgroup of immigrans species group of Drosophila. Interracial hybridization between these two races has given rise to new karyotypic strains called Cytorace 1 and Cytorace 2 (first phase). Further hybridization between Thailand strain of D. n. albomicans and D. n. nasuta of Coorg strain has resulted in the evolution of two more Cytoraces, namely Cytorace 3 and Cytorace 4 (second phase). The third phase Cytoraces (Cytorace 5 to Cytorace 16) have evolved through interracial hybridization among first, second phase Cytoraces along with parental races. Each of these Cytoraces is composed of recombined genomes of the parental races. Here, we have made an attempt to systematically assess the impact of hybridization on karyotypes, morphometric and life history traits in all 16 Cytoraces. RESULTS: The results reveal that in most cases, the newly evolved Cytoraces, with different chromosome constitutions, exhibit decreased body size, better fitness and live longer than their parents. Particularly, Cytorace 5, 6 and 8 have evolved with very much higher range values of quantitative traits than the parents and other Cytoraces, which suggests the role of transgressive segregation in the evolution of these Cytoraces. CONCLUSION: Thus, the rapid divergence recorded in the chromosomes, karyotypes, body size and fitness traits of Cytoraces exhibit the early event of recombinational raciation / speciation in the evolution of the Cytoraces under laboratory conditions.

Animals↗